Electrochemical technology to drive spent lithium-ion batteries (LIBs) recycling: recent progress, and prospects
Abstract
The widespread use of lithium-ion batteries (LIBs) in recent years has led to a marked increase in the quantity of spent batteries, resulting in critical global technical challenges in terms of resource scarcity and environmental impact. Therefore, efficient and eco-friendly recycling methods for these batteries are needed. The recycling methods for spent LIBs include hydrometallurgy, pyrometallurgy, solid-phase regeneration, and electrochemical methods. Compared to other recycling methods, electrochemical methods offer high ion selectivity and environmental friendliness. Assembling research on the recycling and reutilization of spent LIBs, with a focus on the various electrochemical techniques that can enhance these processes, is essential. A thorough analysis of the characteristics and evolution of these methods remains crucial to advancing the field of electrochemical technology in battery recycling. This review first discussed the necessity of recycling spent LIBs from multiple perspectives and briefly introduced the main pyrometallurgical and hydrometallurgical recycling technologies, analyzing their advantages and disadvantages. Moreover, we comprehensively summarized the current applications of electrochemical technology in the recycling of spent LIBs, including pretreatment, leaching, element separation, and regeneration. Then, we analyzed the characteristics and advantages of different electrochemical techniques in the LIB recycling process and discussed the obstacles encountered in the application of electrochemical technology and their solutions. Finally, a comparison between electrochemical technology and traditional recycling processes was provided, highlighting the potential advantages of electrochemical technology in reducing recycling costs and minimizing waste emissions.
Keywords
INTRODUCTION
The continuous growth of the global population and rapid economic development have increased the demand for energy, disturbing the equilibrium between supply and demand. This imbalance has resulted in an increase in energy prices, supply chain disruptions, and a resulting energy crisis[1]. As a result, the advancement of efficient energy storage technologies has emerged as a critical response to these crises internationally. Among these technologies, lithium-ion batteries (LIBs) serve as a preeminent choice for renewable energy storage, providing lightweight construction, eco-friendliness[2], high energy density, and superior specific energy and voltage properties[3]. LIBs also have good capacity retention[4], an extensive operating temperature range, and prolonged service life[5]. These attributes have pushed their widespread integration across various sectors, including portable electronics, aerospace, new energy vehicles, electric bicycles, and medical devices, allowing LIBs to achieve market dominance. According to recent data[6], in 2023, global LIB shipments increased to 1,202.6 GWh, a 25.6% increase from the previous year. Meanwhile, power batteries led with 865.2 GWh, representing 71.94% of the total, while energy storage batteries comprised 224.2 GWh or 18.64%, and small-sized batteries comprised 113.2 GWh or 9.41%. Power and energy storage batteries together accounted for over 80% of global shipments. Projections have indicated that by 2030, driven by commitments to carbon neutrality, emission peaks, and an expanding market for new energy vehicles, LIB shipments could exceed 6,080.4 GWh, with a compound annual growth rate of 22.80%[7].
The rapid expansion of LIB production has led to escalating demand for raw materials, predominantly sourced from non-renewable earth minerals. Concurrently, a surge in LIB shipments is expected to generate a significant volume of waste due to their limited lifespan. A report estimated that by 2030, the global volume of spent LIBs will reach 11 million metric tons[8]. Consequently, transitioning from mineral resources to recycled LIBs as the primary source of raw materials for LIB manufacturing offers multiple benefits. This shift not only diminishes reliance on finite mineral resources and prolongs their availability, but also reduces environmental pollution from battery waste. Additionally, this strategy supports the green and sustainable development of the LIB industry.
Due to the increasing significance of developing and applying recycling technologies for spent LIBs, countries worldwide have acknowledged the importance of recycling these batteries and have enacted various incentive policies. Notably, the United States, Germany, Japan, and China have instituted measures for the recycling of exhausted LIBs[9]. Moreover, the ReCell Center, headed by Argonne National Laboratory, has devised foundational principles for sustainable recycling. These principles encompass strategies for recyclability, direct recycling, repair, regeneration, and recovery of other high-value components[10].
LIBs are fundamentally composed of a cathode (positive electrode), an anode (negative electrode), an electrolyte, and a separator. Additional components include binders, conductive carbon black, current collectors, tabs, and packaging materials [Figure 1A and B][11-12]. The cathode materials comprise lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium nickel cobalt aluminum oxide (NCA), lithium iron phosphate (LFP), and lithium nickel manganese cobalt oxide (NCM). Graphite serves as the predominant material for the anode[13-18]. Owing to the critical metals such as lithium (Li), nickel (Ni), and cobalt (Co) present in cathode materials, recycling efforts of spent LIBs are chiefly directed toward reclaiming these cathode materials.
Figure 1. (A) Components of cylindrical LIBs[11]. Copyright 2020 Wiley[12]. (B) Composition of the conventional rechargeable battery[12]. Copyright 2020 American Chemical Society[12]. (C) Average Li2CO3 price from 2013 to 2023[24]. (D) Global lithium reserves according to USGS 2023 data. (E) Global cobalt reserves according to USGS 2023 data. (F) Global nickel reserves from USGS 2023 data. (G) Global lithium mine production proportions, 2016-2021. (H) Global cobalt mine production proportions, 2016-2021. (I) Global nickel mine production proportions, 2016-2021. (D-I) Figures reprinted with permission from Ref.[29]. Copyright 2023 Springer[29].
Current mainstream recycling processes for spent LIBs primarily include pyrometallurgy, hydrometallurgy, electrochemical methods, and cathode material regeneration. Another promising recycling method involves directly converting spent cathode materials into new materials with high-added value or specific functions, such as novel catalysts or adsorbents with excellent performance, commonly referred to as regenerated functional materials. This recycling technology can shorten the recovery process for spent cathode materials, broaden the application range of the regenerated materials, and provide significant environmental and economic benefits[19]. Compared to other recycling methods, electrochemical recycling technology has gained increasing attention, primarily because electrochemical recycling technology serves as a green and environmentally friendly method, using electrons as a green redox mediator to drive reactions without the need for large amounts of toxic chemicals, and also provides a mild, operationally feasible, and efficient approach that avoids complex, lengthy processes, and harsh reaction conditions. Specifically, electrochemical redox mediation can achieve metal dissolution, metal deposition, separation, and regeneration by adjusting anodic redox pairs (i.e., M/Mn+, H2O/OH, Cl-/Cl2, and Fe2+/Fe3+) and cathodic redox pairs (i.e., Mn+/M, O2/H2O2, H2O2/OH)[20]. Therefore, electrochemical recycling technology offers a wider application range in the recycling process of spent LIBs. During the pretreatment process, by using the spent electrode as the working electrode, active material/graphite can be stripped from the current collector under the action of an applied current and generated bubbles. In the leaching process of spent cathode materials, using electrochemical technology instead of traditional chemical reagents can provide a reaction driving force to greatly reduce the consumption of chemical reagents and the generation of wastewater, and improve the efficiency of metal leaching. In the separation stage, the redox potentials of different metal ions in the leachate differ, and the separation of different metal ions can be achieved by adjusting the electrolysis conditions, thus avoiding the use of extractants in traditional extraction separation processes. In addition, electrochemical technology can achieve the regeneration of spent cathode materials. Adopting electrochemical recycling technology can enhance the integration, compatibility, operability, and controllability of the overall process, making it more conducive for practical industrial applications[21].
In this review, we discuss the imperative of recycling spent LIBs from economic, environmental, and sustainability standpoints. We then summarize existing recycling and utilization technologies for LIBs, encompassing pyrometallurgical, hydrometallurgical, and electrochemical methods. Particular emphasis was placed in this review on the pivotal role of electrochemical techniques in the recycling process, detailing stages such as preprocessing, leaching, separation of elements, and regeneration. We also highlighted the unique features and benefits of various electrochemical methods in recycling LIBs, and concluded by synthesizing these discussions and projecting future directions for the utilization of electrochemical methodologies in this domain.
THE NECESSITY OF RECYCLING SPENT LIBS
Resource properties of spent LIBs
As a highly recyclable secondary resource, spent LIBs contain substantial quantities of valuable metallic elements, including Co, Ni, and Li, with concentrations surpassing those in natural ores[22,23]. The manufacturing cost of LIBs also remains highly dependent on the fluctuation of raw material prices, such as lithium. As shown in Figure 1C, the price of lithium carbonate rapidly increased to $68,100 in 2022, a 440% increase compared to the previous year. However, by 2023, the price of lithium carbonate dropped back to $46,000, a significant decrease of 32.45% compared to 2022[24]. These substantial price fluctuations will inevitably affect the stability of supply and profitability for LIB manufacturers. Therefore, appropriate recycling technologies can not only promote the establishment of a closed-loop and stable supply chain for these materials, but also diminish the complexity of extraction from natural ores. Consequently, this approach may lead to a potential reduction in the cost of LIB materials, providing an economic advantage in the manufacturing of LIBs[25].
Environmental problems of spent LIBs
Increasing demand for LIBs has precipitated a marked increase in spent units. Currently, only a minor portion of these batteries is subjected to recycling and resource recovery, with the majority still relegated to landfills or disposed of illegally[26]. LIBs, which contain heavy metals such as Co, Ni, and manganese (Mn) (all recognized carcinogens), and toxic organic electrolytes, may emit harmful HF gas upon contact with water. As a result, these materials are considered hazardous waste. The improper disposal of these batteries can lead to substantial emissions of noxious substances into the environment, threatening ecological integrity and public health[27]. Consequently, recycling these batteries not only enhances resource efficiency, but also advances the development of a green and sustainable LIBs sector[28].
Uneven distribution of production resources
The essential raw materials used for LIB production are primarily found in a few countries. In terms of the distribution of natural resources, Chile, Australia, and Argentina hold over 70% of the world’s lithium resources, as shown in Figure 1D-F. The Democratic Republic of Congo and Australia account for 66% of global cobalt resources, while 41% of global nickel resources are concentrated in Australia and Indonesia. This uneven distribution of natural resources has led to disparities in the production output of Li, Co, and Ni worldwide[29]. As shown in Figure 1G-I, the production of lithium in Australia and nickel in Indonesia demonstrated a yearly increase from 2016 to 2023, with the Democratic Republic of Congo consistently remaining the top global producer of cobalt[29]. The centralization of these vital resources can significantly influence the raw material availability for LIBs, resulting in notable fluctuations in the cost and stability of the supply chain[30]. Recycling spent LIBs presents a valuable opportunity, as it can overcome the geographical constraints on resource availability, thus stabilizing the supply chain and reducing manufacturing costs[31-32].
TRADITIONAL RECYCLING STRATEGIES FOR SPENT LIBS
The recycling process for spent LIBs primarily consists of two key stages: pretreatment and the recovery of valuable metals[33-37]. Pretreatment involves steps such as battery discharge, disassembly, cell crushing, and sieving. Following pretreatment, the positive and negative electrode materials are converted into powder form, and traditional metallurgical techniques are then used to separate and recover valuable metals from the powder. The metals and their compounds retrieved can subsequently be employed in the manufacturing of new LIBs or for other purposes, facilitating resource reuse and the environmentally friendly treatment of pollutants.
Currently, conventional recycling processes for spent LIBs primarily consist of pyrometallurgy and hydrometallurgy[38], with the respective recycling flows depicted in Figure 2. Pyrometallurgy, a high-temperature metallurgical process, is extensively utilized in industrial production, especially in Europe and North America, owing to its simplicity, large processing capacity, and efficiency. Conversely, hydrometallurgy utilizes acid (or alkali) aqueous solutions to extract valuable metals from spent LIBs. This method is prevalent used in China, given its high recovery rates, low energy consumption, minimal toxic gas emissions, and high purity of the recovered metals.
Pyrometallurgical recovery technology
Pyrometallurgical technology encompasses a series of physical and chemical reactions at high temperatures, enabling the retention of metals in the positive electrode material in alloy form and facilitating their separation from impurities. Typically, a reducing agent is added during the reaction to collect different metals under a reducing atmosphere as either alloy or slag. Figure 3A and B illustrates the typical process flow. Pyrometallurgical processes consist of three main steps. The initial step involves crushing the entire battery and processing it in a rotary kiln for reduction roasting, segmented into low and medium-temperature phases. The aim of the low-temperature stage, at approximately 300 °C, involves evaporating the electrolyte and minimizing explosion risks. The medium-temperature phase is then increased to 700 °C, utilizing a negative electrode graphite, separator, and binder, which generates reducing gas upon heating, as reducing agents for preliminary reduction of Ni, Co, and Mn. The second step elevates the temperature above 1,200 °C for further reduction and smelting, allowing Ni, Co, and copper (Cu) to enter the alloy phase, which can be subsequently separated by magnetic separation[39]. The third step applies hydrometallurgical technology for alloy leaching and separation, facilitating the recycling of valuable metals from the positive electrode material. The primary pyrometallurgical recycling processes for LIBs include high-temperature smelting and calcination, with the latter subdivided into direct, atmosphere-assisted, and salt-assisted calcination. Compared to high-temperature smelting, calcination operates at lower temperatures, potentially improving metal recovery rates by producing water-soluble salts. This method can reduce acid consumption and the emission of toxic gases in subsequent stages.
High-temperature smelting technology for LIB recycling was first introduced in the Umicore battery recycling process[40]. Instead of mechanically preprocessing individual batteries, this process utilizes specialized ultra-high temperature (UHT) technology, incorporating slagging agents, to directly smelt spent batteries at elevated temperatures. This process can produce an alloy containing valuable metals (Co, Ni, Fe, and Cu), which can be subsequently separated through hydrometallurgical technology [Figure 4A][41]. Plastics, solvents, and graphite will be incinerated, exiting in gaseous form, while Li, aluminum (Al), and Mn will be lost to the slag and not recovered [Figure 4B][42]. UHT technology facilitates the safe processing of large volumes of complex metallic waste. The mixture, containing batteries, coke, and slagging agents (limestone, sand), is introduced into the furnace, with optimal feedstock comprising 30-50 wt% spent batteries to yield economically viable cobalt and nickel products. Preheated air at 500 °C is then injected at the furnace base, which can be segmented into three temperature zones, namely, preheating, plastic pyrolysis, and smelting. The inaugural pilot plant was operational for several years in Hofors, Sweden. Drawing from this experience, a second-generation pilot plant was launched in Hoboken, Belgium, in 2011, with an annual capacity of 7,000 tons. The primary benefits of this process include the elimination of mechanical battery preprocessing and high recovery rates of Co, Ni, and Cu. However, this process necessitates extremely high temperatures, exceeding 1,500 °C, resulting in considerable lithium loss and leading to increased energy consumption and resource depletion.
Figure 4. (A) Flowsheet showing the Umicore/Rhodia’s VAL'EAS™ battery scrap recycling process[41]. Copyright 2014 Elsevier[41]. (B) Detailed illustration of the smelting process[42]. Copyright 2022 Elsevier[42]. (C) Recovery of spent LIBs through reduction roasting and facile acid leaching processes[43]. Copyright 2020 Elsevier[43].
Zhang et al. explored the recovery of valuable metals from spent LIB cathodes [Figure 4C] using a reduction roasting approach that capitalized on repurposed graphite from anode materials[43]. This two-step method consisted of a reduction roast at 600 °C for 3 h, followed by leaching with sulfuric acid (H2SO4), thus eliminating the need for additional reducing agents. The findings demonstrated that this process achieved leaching rates exceeding 99% for Ni, Co, and Li, and over 97% for Mn. This innovative method not only repurposed waste graphite, enhancing energy efficiency, but also precluded the substantial generation of hydrogen gas during metal recovery. Yan et al. also suggested an improved process of carbothermal reduction for the preferential extraction of lithium, which was combined with water leaching from spent Li(NixMnyCo1-x-y)O2 (NMC) batteries[44]. When the roasting temperature was below 800 °C, Co and Ni were reduced to their elemental forms, while Mn remained in oxide form, and Li was converted to Li2CO3. When the roasting temperature exceeded 900 °C, Li was mainly converted to Li2O. Lithium was extracted as lithium hydroxide and lithium carbonate with an efficiency of 93% following water leaching for 30 min using a 5 mL/g liquid-to-solid ratio. The researchers also investigated the effect of impurities on the recovery rate of Li, and determined that Cu had no significant effect. However, the lithium recovery rate decreased in the presence of Al due to the formation of lithium aluminate.
The pyrometallurgical process can facilitate the rapid conversion of valuable metals into alloys at elevated temperatures, predominantly using iron (Fe) ore-based techniques for cobalt and nickel extraction. This method has a straightforward operation and efficient elimination of organic materials, binders, plastics, and other components from spent LIBs, making it appropriate for industrial-scale production. Nevertheless, this process has considerable disadvantages, including excessive energy consumption, significant material loss yielding high input costs, inadequate purity of the recovered valuable metals, and the production of hazardous substances such as dioxins and furans. These issues result in substantial secondary pollution and pose challenges in complying with contemporary environmental protection standards.
Hydrometallurgical recovery technology
Hydrometallurgy serves as a well-established and widely used technology for recycling spent LIBs. This method mainly utilizes inorganic acids, organic acids, ammonia-based reagents, and similar chemicals to leach valuable metals from pre-treated cathode active materials into a solution. Subsequently, valuable metals can be separated from this solution through processes such as precipitation and extraction. The hydrometallurgical process flow is shown in Figure 5.
Hydrometallurgy involves two primary processes, namely, leaching and purification. The decision between common leaching methods, such as acid and alkali leaching, depends on the physical and chemical properties of the target metals. Acid leaching utilizes inorganic agents such as hydrochloric acid (HCl),
Summary of some research results for leaching of spent LIBs in acid leaching
Acid | Cathode materials | Leaching agent | T (°C) | S/L ratio (g/L) | Time (min) | Leaching rate (%) | Ref. |
Inorganic acids | LiFePO4 | 2.5 M H2SO4 | 60 | 100 | 240 | Li:97; Fe:98 | [45] |
1.0 M HNO3 + 1.7 vol% H2O2 | 70 | 10 | 30 | Li: 99; Fe: 99 | [46] | ||
Li2CoO2 | 4.0 M HCl | 80 | - | 120 | Li: 97; Co: 99% | [47] | |
2.0 M H2SO4 + 2.0 vol% H2O2 | 60 | 33 | 120 | Co: 96.3; Li: 87.5 | [48] | ||
2.0 M H2SO4 + 5.0 vol% H2O2 | 80 | 50 | 60 | Co: > 99; Li: > 99 | [49] | ||
2.0 M H2SO4 + 8.0 vol% H2O2 | 75 | 50 | 60 | Co: 98 | [50] | ||
1.0 M HNO3 + 1.7 vol% H2O2 | 75 | 10 | 30 | Co: 99; Li: 99 | [51] | ||
Mixture | 1.0 M H2SO4 | 95 | 50 | 240 | Co: 66.2; Li: 93.4; Ni: 96.3; Mn: 50.2 | [52] | |
1.0 M H2SO4 + 5.0 wt% H2O2 | 95 | 50 | 240 | Co: 79.2; Li: 94.5; Ni: 96.4; Mn: 84.6 | [53] | ||
1.0 M H2SO4 + 0.78 wt% NaHSO3 | 95 | 20 | 240 | Co: 91.6; Li: 96.7; Ni: 96.4; Mn: 87.9 | [53] | ||
4.0 M HCl | 80 | 20 | 60 | Co: 99.5; Li: 99.9; Ni: 99.8; Mn: 99.8 | [54] | ||
Organic acids | Li2CoO2 | 1.5 M succinic acid + 4.0 vol% H2O2 | 70 | 15 | 40 | Li: 96; Co: 100 | [55] |
1.25 M ascorbic acid | 70 | 25 | 20 | Li: 98.5; Co: 94.8 | [56] | ||
1.25 M citric acid + 1.0 vol% H2O2 | 90 | 20 | 30 | Li: 91; Co: 91 | [57] | ||
1.0 M H2C2O4 | 80 | 50 | 120 | Li: 98 | [58] | ||
1.5 M malic acid + 2.0 vol% H2O2 | 90 | 20 | 40 | Li: 94; Co: 93 | [59] | ||
NCM | 1.2 M DL-malic acid + 1.5 vol% H2O2 | 90 | 40 | 30 | Co: 94.3; Li: 98.9; Ni: 95.1; Mn: 96.4 | [60] | |
1.0 M acetic acid + 6.0 vol% H2O2 | 70 | 20 | 60 | Co: 97.7; Li: 98.4; Ni: 97.3; Mn: 97.1 | [61] | ||
2.0 M maleic acid + 4 vol% H2O2 | 70 | 20 | 60 | Co: 98.4; Li: 98.2; Ni: 98.1; Mn: 98.1 | [61] | ||
1.0 M citric acid + 12 vol% H2O2 | 60 | 80 | 40 | Total metals: > 98 | [62] | ||
0.5 M citric acid + 1.5 vol% H2O2 | 90 | 20 | 60 | Co: 99.8; Li: 99.1; Ni: 98.7; Mn: 95.2 | [63] |
Leaching methods can be characterized by their high recovery efficiency, low energy consumption, and rapid reaction rates, making them highly suitable for recycling spent LIBs. However, the non-selective nature of acid leaching increases the complexity and expense of metal separation. Inorganic acid leaching typically requires high acid concentrations, resulting in significant corrosiveness and necessitating specialized equipment. Additionally, this process often mandates the extensive addition of water or alkalis for neutralization, complicating post-treatment procedures. The leaching process will emit hazardous gases, presenting risks to human health and the environment. When utilizing organic acids as leaching agents, the process remains limited to low solid-to-liquid ratios and suffers from slow leaching rates, making it impractical for large-scale industrial use. Furthermore, the prolonged degradation cycles of organic acids contribute to potential environmental pollution.
Ammonia leaching has recently attracted significant interest due to its selective extraction capabilities targeting metals such as Li, Ni, Co, Al, Fe, and Mn. Nevertheless, concerns regarding additional wastewater generation remain a challenge. The intricate binding mechanisms between the metals of value and ammonia-based leachates remain improperly understood and require more thorough investigation. Subsequent to hydrometallurgical leaching, the leachate contains valuable metal ions such as Li+, Ni2+, Co2+, and Mn2+, and impurity ions such as Fe2+, Al3+, and Cu2+. Conventional separation techniques such as solvent extraction, chemical precipitation, and electrodeposition have been typically employed to isolate and concentrate these valuable metals from complex mixtures.
ELECTROCHEMICAL TECHNOLOGY TO DRIVE SPENT LIBS RECYCLING
Electrochemical technology has found extensive application in the extraction of precious metals such as gold and silver from industrial wastewater[64], valuable metals from tailings[65], trace metals from solid waste[66], and lithium from brine[67-70]. This popularity is due to the high selectivity of electrochemical methods for different metal ions, enabling the dissolution or deposition of specific metal elements by adjusting electrolysis conditions, thus facilitating the separation of various metal elements.
Electrochemical pretreatment
Methods for separating current collectors from active materials include mechanical processing[71], thermal treatment[72], leaching[73], and solvent treatment[74]. Mechanical processing consists of crushing and sieving to isolate the cathode material powder, which unfortunately produces a powder material contaminated with impurities such as copper or aluminum from the current collector. Thermal treatment involves the decomposition of the binder [polyvinylidene fluoride (PVDF)] at elevated temperatures to segregate the cathode active powder, though at a significant energy cost. Leaching employs substantial quantities of acid to dissolve copper or aluminum foil, consequently producing harmful gases. Solvent treatment utilizes organic solvents to dissolve PVDF, facilitating the separation of cathode powder. However, this method consumes considerable volumes of solvents, posing a risk to human health. To enhance separation efficiency between the current collector and cathode material, researchers have explored the electrochemical technique to separate the active material and current collector.
Cao et al. developed a method for separating copper foil from graphite in the anode by using the disassembled anode of LIBs as the cathode, graphite as the anode, and employing Na2SO4 (1.5 g/L) solution as the electrolyte, as shown in Figure 6A[75]. At 30 V, the complete separation of the current collector (copper foil) and graphite was achieved within 25 min. The generation of hydrogen gas on the surface of the copper foil during electrolysis created gaps, facilitating the detachment of graphite. Moreover, this method reduced the bonding force, increasing the separation efficiency. The resulting copper foil was recyclable without additional processing. Residual Li+ from the spent graphite entered the solution during electrolysis, and dissolved copper could be reclaimed through precipitation to a lesser extent. The purity of the regenerated graphite was approximately 95%, with energy consumption of around 4.70 kWh/kg.
Figure 6. (A) Graphite anode prior to electrolysis, accompanied by the recovered copper foil and anode active materials post-electrolysis[75]. Copyright 2021 Elsevier[73]. (B) Schematic of electrolytic separation. (C) Influence of supplied voltage on lithium dissolution and separation duration. (D) Impact of inter-electrode spacing on lithium dissolution and separation duration. (E) Concentration effect of sodium sulfate on lithium dissolution and separation duration. (F) Consequences of electrolysis duration on lithium recovery and separation time. (B-F) Figures reprinted with permission from Ref.[74]. Copyright 2021 Elsevier[75].
The previously mentioned electrochemical methods can also facilitate the separation of aluminum foil from active materials, though with changes in the electrode reactions. Chu et al. employed a neutral Na2SO4 solution as the electrolyte, positioning the dismantled cathode of NCM batteries as the electrolytic anode and utilizing either copper or aluminum as the electrolytic cathode, as shown in Figure 6B[76]. Oxygen gas was also produced between the aluminum foil and active materials during electrolysis. Similarly, echoing the charging dynamics of LIBs, Li+ migrated from the cathode material into the solution, achieving the separation of lithium and transition metals. At an optimal electrolysis voltage of 30 V, the lithium dissolution efficiency reached 77%, with the separation of Ni, Co, and Mn in their solid forms
Electrochemical leaching
Hydrometallurgical techniques for recycling LIBs present widespread applicability and yield high-purity products, making these techniques a favored method. These techniques encompass dissolving valuable metals from depleted batteries into acidic or alkaline solutions, followed by purification processes such as extraction and precipitation to eliminate any impurities, culminating in the production of high-purity products. The leaching step has shown to be especially pivotal, significantly influencing the recovery efficiency of valuable metals. However, to improve leaching efficiency, substantial amounts of leaching solution are typically used, leading to the production of large volumes of wastewater. By integrating electrochemical methods for leaching positive electrode materials, these challenges can be mitigated, with electrochemical reactions relying on an external electric current.
Lei et al. devised a pioneering process for recycling LIBs by integrating reduction roasting with electrochemical leaching, as shown in Figure 7A-D[77]. The process involved reduction roasting of the spent LiNi1/3Co1/3Mn1/3O2 material at 1,600 °C for 120 min, which released O2 and disrupted its layered structure, resulting in a mixture of Li2CO3, NiO, Co3O4, MnO2, and Mn2O3. This disruption of the layered structure enhanced valuable metal leaching. The roasted material was subsequently encased in polypropylene bags and attached to a graphite cathode, with a titanium (Ti) anode. The setup utilized G1204 [an anion exchange membrane (AEM)] as the separator and 1.5 M H2SO4 as the electrolyte. Subsequently, the roasted product underwent further reduction through electrochemical methods at room temperature, with a current of 0.8 A applied for 150 min. The leaching rates of Li, Co, Ni, and Mn were recorded as 100, 90.53, 90.59, and 66.40%, respectively, as shown in Figure 7E. Compared to identical leaching conditions involving direct acid leaching and the electrochemical leaching of thermally treated roasted spent cathode materials, this method proved to substantially minimize the utilization of chemical reagents such as reducing agents and acid, while also achieving higher metal recovery rates and yielding greater economic benefits.
Figure 7. (A) Flowsheet illustrating the recovery of spent LIBs through thermal reduction and electrochemical leaching processes. (B) Mechanism of the reaction for the direct electrochemical leaching of cathode materials. (C) Mechanism of the reaction for thermal reduction process followed by acid leaching. (D) Mechanism of the reaction involving thermal reduction process followed by electrochemical leaching (green represents reactants, with red indicating substances introduced during the leaching processes). (E) Comparative evaluation of metal leaching effectiveness among the three methods: (1) direct electrochemical leaching; (2) thermal reduction process combined with acid leaching; (3) thermal reduction process coupled with electrochemical leaching. (A-E) Figures reprinted with permission from Ref.[77]. Copyright 2021 American Chemical Society[77]. (F) Schematic representation of the electrochemically assisted leaching of metals from MOFC, where the leachate, carbon/graphite materials, and electrowon copper can be separately recovered. (G) Leaching efficiency of metals and specific energy consumption at various tested pulp densities. (F-G) Figures reprinted with permission from Ref.[78]. Copyright 2020 Elsevier[78].
Electrochemical leaching can also be used to process mixtures of different spent LIB materials. Diaz et al. developed a method using electrochemical techniques to extract valuable metals from mixed crushed LIB metal oxide filter cakes (MOFC), composed of LiCoO2, LiMnxCoyO2, LiNixMnyCozO2, LiCuxMnO2,
Electrochemical separation
After leaching the positive electrode materials, the efficient separation of diverse valuable metal elements from the intricate leach solution serves as a vital process step in the recycling of spent LIBs. Due to the high ion selectivity of electrochemical techniques, multiple metal elements in the solution can be effectively separated, with the resulting metal products post-separation exhibiting greater purity, making them suitable for direct use in the regenerative synthesis of cathode materials.
Electrochemical deposition
Electrochemical deposition involves the process in which metal ions of value within the leaching solution obtain electrons under an applied electric field, subsequently depositing on the cathode to form a coating. The order in which electrochemical deposition of varied metal ions occurs will be dictated by the properties of the metal ions, electrolyte composition, pH, temperature, and current density. Consequently, by modifying these conditions, specific metal ions can be selectively reduced, facilitating the separation of valuable metals. Compared to alternative separation techniques, electrochemical deposition offers benefits such as straightforward raw materials, reduced costs, a concise process, high product purity, and excellent performance.
Prabaharan et al. employed electrochemical techniques to extract Co and Mn from spent LIBs
Figure 8. (A) The method of electrodeposition for the separation of cobalt from spent LIBs. Characteristics of cobalt metal deposition at (B) a pH of 2.5 and (C) a pH of 4.5. (A-C) Figures reprinted with permission from Ref.[79]. Copyright 2017 Elsevier[79] (D) Schematic illustration of the electrodeposition apparatus[83]. Copyright 2019 Royal Society of Chemistry[83].
Cathode:
Anode:
The pH of the electrolyte was found to significantly influence the quality of deposited cobalt metal. As the pH increased from 1 to 4.5, the current efficiency of Co deposition improved from 33.2% to 97.1%, although the purity of the product declined to 85.3%. When the pH was maintained between 2 and 2.5, the deposited cobalt metal demonstrated enhanced brightness, and the impurity content remained below 0.8%. Optimal conditions for complete deposition of Co and Mn included an electrolyte pH range of 2 to 2.5, a temperature of 90 °C, and a current density of 200 A/m2, while the recovery rates for Co, Cu, and Mn exceeded 96%, 97%, and 99%, respectively, leading to product purities of 99.2% for cobalt metal, 99.5% for copper metal, and 96% for MnO2.
Freitas et al. employed HCl and H2O2 to leach spent LiCoO2 powder materials, and subsequently used the leaching solution as the electrolyte for cobalt recovery using the electrochemical method[80]. As the pH increased, the reductive potency of hydrogen ions diminished, enhancing the current efficiency of cobalt deposition. The maximum current efficiency, amounting to 96.90%, was achieved at a pH of 5.40, while cobalt deposition nucleation at the cathode was continuous. By contrast, at a pH of 2.70, the nucleation shift to an instantaneous mode affected the morphology of the cobalt deposits[81-82].
In addition to metals such as Ni, Co, Mn, and Li, the leachate from spent LIBs cathode materials contains impurities including Fe, Cu, and Al. Typically, Al can be precipitated by adjusting the pH of the leachate. However, due to the similar precipitation pH values of Cu2+, Co2+, and Ni2+, pH adjustment alone remains insufficient for Cu removal. Freitas et al. explored the impact of Cu presence in the leachate on Co electrodeposition[80]. The leaching of spent cathode materials containing Co and Cu was conducted using
If a notable difference in the reduction potentials of valuable metal ions in the leach solution is present, electrodeposition can separate and recover different valuable metals, achieving high metal purity. However, if the reduction potentials of valuable metal ions are similar (i.e., Co and Ni), electrodeposition will occur simultaneously for metals with close reduction potentials, leading to decreased metal purity. Therefore, in the recycling process of spent LIB cathode materials, Ni and Co will be initially separated from the leaching solution via extraction, followed by electrodeposition to independently prepare elemental Ni and Co on the cathode.
Electrodialysis
Electrodialysis involves the movement of various metal ions at distinct rates across a semi-permeable membrane, driven by an external electric field and influenced by their charge and size disparities. This method facilitates the selective migration of ions, enabling the efficient separation of valuable metals. In the recycling of spent LIBs cathode materials, electrodialysis has been extensively employed for the separation and recovery of critical metals such as Ni, Co, and Li, offering vital technical support for the recycling processes of LIBs.
In the leaching solution of spent LIB cathode materials, lithium ions coexist with other transition metal ions. To efficiently separate lithium from transition metal ions, Iizuka et al. introduced a method utilizing BPM electrodialysis in conjunction with metal ion complexation, which specifically enhanced the separation of Li+ and Co2+ in the leaching solution, with ethylenediaminetetraacetic acid (EDTA) serving as the complexing agent[84,85]. At pH levels above 4, the formation of anionic groups CoY2- resulted from the complexation of EDTA with Co2+, leaving Li+ as the cations in the solution. Thus, exploiting the charge disparity, Co2+ and Li+ separation could be realized through electrodialysis. Figure 9A presents the configuration of the electrodialysis system, which included three electrolysis cells separated by BPMs, AEMs, and cation exchange membranes (CEMs). The cobalt recovery cell was linked to the anode (stainless steel), while the lithium recovery cell was connected to the cathode (Ti/Pt). The leaching solution and EDTA were introduced into the feed cell, where under the influence of an electric field, CoY2- migrated to the cobalt recovery cell through the AEM, and Li+ moved to the lithium recovery cell through the CEM, thus separating Li+ from Co2+. Figure 9B-G illustrates the variations in Li+ and Co2+ concentrations across the three cells over time, demonstrating how the Li and Co concentrations progressively increased in their respective recovery cells. The selectivity of Li and Co achieved a notable value of 99%.
Figure 9. (A) Method principle for Co and Li separation based on electrodialysis. Variations over time in Li quantities within the cells; impact of initial pH levels: (B) feed cell, (C) Li recovery cell, and (D) Co recovery cell. Variations over time in Co quantities within the cells; impact of initial pH levels: (E) feed cell, (F) Li recovery cell, and (G) Co recovery cell. (A-G) Figures reprinted with permission from Ref.[85]. Copyright 2023 Elsevier[85].
In the electrodialysis process, the ion exchange membrane could easily capture and stabilize cobalt and lithium ions, leading to lower recovery rates for these metals. To address this issue, a semi-batch experiment was conducted. Initially, the feed solution was added to the feed cell and operated for 30 min, after which it was replenished with a fresh solution. This replacement cycle was repeated every 30 min for a total duration of 150 min. After each 30 min of operation, the metal concentration in the feed cell significantly decreased, approaching zero over time [Figure 10A]. Despite the increase in cycles, the metal ion removal rate from the feed solution remained consistent. Conversely, the concentration of lithium ions in the lithium recovery cell and cobalt in the cobalt recovery cell linearly increased with operation time, as shown in Figure 10B and C. These findings suggested that this method not only effectively separated lithium and cobalt ions from the feed solution but also concentrated the metals through semi-batch operation.
Chan et al. pioneered a method employing electrodialysis technology for the separation of Li, Co, Mn, and Ni from the LiNi0.33Mn0.33Co0.33O2 (NMC111) cathode material of spent LIBs[86]. This process encompassed the EDTA-mediated complexation of Ni and Co, followed by three-stage electrodialysis for the separation of Li, Co, Mn, and Ni, the subsequent decomplexation of Ni and Co with EDTA, and a purification step to recover the final products. As shown in Figure 11A, the electrodialysis apparatus comprised Pt/Ti anodes, 316 stainless steel cathodes, and five chambers spatially arranged between two CEMs and two AEMs.
Figure 11. (A) Schematic diagram showing the electrodialysis experimental setup for the separation of Li, Ni, Mn, and Co from NMC111. Principles of the three-stage electrodialysis process for separating Li, Ni, Mn, and Co from NMC111: (B) separation of Ni in Stage 1; (C) Separation of Co in Stage 2; (D) separation of Li from Mn in Stage 3. (A-D) Figures reprinted with permission from Ref.[86]. Copyright 2012 Elsevier[86].
The separation of Li, Co, Mn, and Ni from NMC111 via electrodialysis consisted of a three-stage process: Ni in Stage 1; Co in Stage 2; and Li and Mn in Stage 3. During Stage 1, as shown in Figure 11B, the leachate comprised Li+, Mn2+, Co2+, Ni2+, and SO42-. The introduction of EDTA selectively complexed with Ni to form anionic Ni-EDTA species (NiHY- and NiY2-). Driven by an electric field, NiHY-, NiY2-, and SO42- ions traversed the AEM into the Ni-EDTA complex chamber, where they reacted with H+ migrating from the electrode rinsing chamber to form
In Stage 2 [Figure 11C], the solution originating from the metal chamber of Stage 1 contained Li+, Mn2+, Co2+, Na+, and SO42- ions. The addition of EDTA preferentially formed Co-EDTA complex anions (CoHY- and CoY2-). Similar to Stage 1, CoHY-, CoY2-, and SO42- ions were transported through the AEM to the Co-EDTA complex chamber, where they combined with H+ ions migrating from the electrode rinsing chamber to form CoH2Y and H2SO4. Concurrently, Li+, Mn2+, and Na+ were transported through CEM to the metal chamber, and combined with SO42- ions migrating from the electrode rinsing chamber to form Li2SO4, MnSO4, and Na2SO4. These products served as the feed solution in Stage 3, achieving the separation of Co from Li and Mn in Stage 2.
In Stage 3 [Figure 11D], the solution from the metal chamber of Stage 2 contained Li+, Mn2+, Na+, and SO42-. Since Mn2+ ions did not completely form Mn-EDTA complex anions, changing the membrane configuration in the electrodialysis cell with monovalent CEMs enhanced selectivity for monovalent over divalent cations. Consequently, SO42- ions passed through AEM to the H2SO4 compartment, joining H+ ions migrating from the electrode rinse compartment to produce H2SO4. Simultaneously, Li+ and Na+ ions were transported through the monovalent CEM to the Li2SO4 compartment, where they merged with SO42- ions migrating from the electrode rinsing compartment, forming Li2SO4 and Na2SO4. Mn2+ ions were hindered by monovalent CEM and retained in the feed compartment. Thus, Li was separated from Mn in Stage 3.
During the electrodialysis process, a 99.3% separation of Ni was achieved in the first stage when the molar ratio of EDTA to Ni was 1.1. In the second stage, with a molar ratio of EDTA to Co of 1.2, 87.3% of Co was separated. In the third stage, monovalent CEM facilitated the sequential separation of approximately 99% of Li and Mn. Post-experiment, Ni and Co were desorbed from EDTA at a pH below 0.5, allowing for the recovery of EDTA solids. Selective precipitation was then utilized to recover all four metals with purities exceeding 99%.
Due to the intricate composition of spent LIB cathode materials, which resulted in a diverse array of metal cations in the leachate, simple electrodialysis techniques were found to be inadequate for separation. The addition of chelating agents to form complexes with specific metal ions, converting them into anions for separation from other cations, offers a viable approach. Nevertheless, this method remains constrained by protracted separation times and the increased consumption of reagents.
Electrochemical lithium stripping
Electrochemical lithium stripping, grounded in the charge and discharge mechanisms of LIBs, employs electrical current instead of chemical reagents to drive reactions, thus facilitating selective lithium-ion removal from positive electrode materials. This approach can significantly diminish reagent consumption and circumvent lithium loss, thereby enhancing lithium recovery rates.
To recover the cathode material LiMn2O4, a slurry electrolysis method was proposed for the recuperation of Li and Mn [Figure 12A][87]. In the electrolytic cell, a filter cloth (< 50 μm) was employed to segregate the anode and cathode chamber. The electrolyte comprised a mixed solution of H2SO4 and MnSO4, with graphite (cathode) and ruthenium-plated titanium electrode (anode), which was operated at 90 °C. Spent LiMn2O4 was introduced into the cathode chamber and dispersed. LiMn2O4 powder dissolved in the cathode chamber during electrolysis, releasing Mn2+ and Li+ ions [Figure 12B]. The influence of H2SO4 and MnSO4 concentrations, along with slurry and current densities, on the rates at which lithium and manganese leached is shown in Figure 12C-J. Optimal conditions included a slurry concentration of 75 g/L, a current density of 40 mA/cm2, a reaction time of 20 h, and a 1 M solution of H2SO4 and MnSO4. Under these conditions, the leaching rates of lithium and manganese reached 99% and 92%, respectively, with cathode and anode current efficiencies of 77% and 62%. After electrolysis, Mn2+ was oxidized to Mn4+ and precipitated as MnO2 in the anode chamber, while Li+ in the cathode reacted with Na2CO3 to produce
Figure 12. (A) Schematic representation of cathode material LiMn2O4 electrolysis. (B) Mechanism diagram of the cathode material LiMn2O4 electrolysis. Impact of electric current density on (C) the leaching efficiency, and (D) electrode current efficiency and cell voltage. Influence of H2SO4 concentration on (E) the leaching efficiency of Mn and (F) current efficiency. Impact of density on (G) leaching efficiency and (H) current efficiency. Influence of MnSO4 concentration on the (I) leaching efficiency and (J) current efficiency. (A-J) Figures reprinted with permission from Ref.[87]. Copyright 2019 American Chemical Society[87].
Li et al.[88] introduced a method for recycling LiFePO4 cathode materials that integrated the charging dynamics of LiFePO4 batteries with a slurry electrolysis strategy, as illustrated in Figure 13A. This method employed an electrolytic cell divided into anode and cathode chambers by an AEM, with sodium chloride serving as the electrolyte, and Ru-coated Ti electrodes facilitating electrolysis. Within the anode chamber, used LiFePO4 underwent oxidation under a positive potential to yield FePO4, which liberated lithium ions into the electrolyte. Due to the insolubility of FePO4 in water, it could be easily isolated through filtration. Concurrently, in the cathode chamber, a hydrogen evolution reaction produced sodium hydroxide as a secondary product. The impact of variables such as the leaching time, electric current density, sodium chloride concentration, and LiFePO4 concentration on lithium extraction is detailed in Figure 13B-E. This method successfully extracted over 98% of lithium into the electrolyte and recovered more than 96% of iron in the form of FePO4, consuming 2,613.33 k/Wh of energy. Electron-driven reactions during slurry electrolysis negated the necessity for chemical reagents, such as oxidizing agents or acids. Filtration of the anode chamber yielded FePO4, and the addition of sodium carbonate (Na2CO3) to the filtrate, thus, facilitated the recovery of lithium ions as LiCO3.
Figure 13. (A) Diagram illustrating the electrolysis process. Impact of (B) leaching duration, (C) electric current density, (D) sodium chloride concentration, and (E) LiFePO4 concentration on the leaching efficiency of lithium[87]. (A-E) Figures reprinted with permission from Ref.[88]. Copyright 2019 Elsevier[88].
Based on this method, a process route was proposed for the recycling of LiFePO4 cathode materials through slurry electrolysis, as illustrated in Figure 14. The spent LiFePO4 underwent oxidation and delithiation in the anode chamber due to electron activity. Concurrently, in the cathode chamber, the hydrogen evolution reaction occurred, producing NaOH. A minor amount of Cl2 released during the slurry electrolysis process could be absorbed by the NaOH solution in the cathode chamber. More than 99% of Li could be leached into the electrolyte, resulting in an anolyte containing 7.55 g/L of Li. The high efficiency and selectivity of this process could enable the recovery of the most valuable elements without the need for prior separation and purification. The purity of the recovered FePO4 reached 99.15%, allowing its use as a raw material for synthesizing LiFePO4. The generated NaOH in the cathode electrolyte aided in removing Fe from the anode electrolyte. After filtration, Li2CO3 precipitated through evaporation and the addition of Na2CO3, reaching a purity of 99.69%. The resultant mother liquor, with a Li content of 2.53 g/L and Na content of 35.72 g/L, could be recycled as a cathode electrolyte. An economic analysis for recycling 1 ton of spent LiFePO4 material was performed, and the costs for reagents and energy were identified as $71.45 and $395.15, respectively, while the revenue from the sale of Li2CO3, FePO4, and NaOH products was approximately $2,846.01, demonstrating the economic viability of this recycling technology.
Employing NaCl as the electrolyte can decrease processing costs, while using lithium salts as electrolytes in both the anode and cathode can remove impurity elements and enhance conductivity. Li et al. utilized
Electrochemical regeneration
One of the primary failure mechanisms of LIB cathodes is the ongoing loss and consumption of Li+ during cycling. Consequently, cathode material repair can be achieved by directly replenishing Li. Electrochemical regeneration processes often utilize conventional three-electrode or two-electrode systems, with the degraded cathode material acting as the working electrode for Li+ insertion and structural restoration. The application of a cathodic potential to the depleted cathode serves as the principal driving force, effectively initiating the regeneration process and significantly reducing the activation energy required for Li+ migration to lithium vacancies. This can lead to lithiation and structural repair of the material. After replenishing Li, the cathode material generally requires annealing in a specific atmosphere to completely restore its crystal structure, thus tightly organizing Li atoms within the structure.
Zhang et al. presented a technique for rejuvenating LiCoO2 cathode materials by electrochemically driving Li+ insertion into the depleted LixCoO2[90]. As shown in Figure 15, the electrochemical apparatus included the cathode (spent LixCoO2), anode (platinum foil), and reference electrode [Ag/AgCl saturated with KCl,
Figure 15. (A) Method for electrochemically inserting Li+ into LixCoO2 electrodes from the spent LIBs, thus generating new LiCoO2 materials. (B) The proposed mechanism for directly regenerating LiCoO2 materials through the electrochemical insertion of Li+ ion into the LixCoO2 electrode. Cycling performance of the Li/LiCoO2 electrode from (C) the regenerated LiCoO2 electrode and (D) commercial LiCoO2 electrode at C/5 current rate. (A-D) Figures reprinted with permission from Ref.[89]. Copyright 2020 American Chemical Society[90].
Yang et al. recycled spent LixCoO2 from dismantled LIBs, employing it as the cathode[91]. LiCoO2 was used as the anode with the electrolyte of Li2SO4, facilitating the integration of Li+ into LixCoO2 through electrolysis, as shown in Figure 16A. After the working electrode voltage reached the cutoff point, LixCoO2 fully transitioned to LiCoO2. The reduced material underwent sintering at 700 °C for 6 h, yielding the regenerated product. The process then involved utilizing the LiCoO2 electrode to replenish the depleted Li+ in the electrolyte. As shown in Figure 16B, compared to conventional pyrometallurgy and hydrometallurgy, this method drastically reduced energy consumption to 6 mJ/kg and presented significant prospects for advancement.
Figure 16. (A) The electrolytic cell used in the re-lithiation process under higher current density (0.4 mA/cm2). (B) Comparative analysis of energy consumption between pyrometallurgy, hydrometallurgy, and direct recycling approaches for LiCoO2. Figures reprinted with permission from Ref.[91]. Copyright 2020 Wiley[91].
In addition to directly replenishing the failed cathode material through electrochemical methods, another technique involves synthesizing the cathode material directly through electrochemical processes post-leaching, minimizing subsequent elemental separation steps and facilitating the direct reuse of the cathode material.
Wang et al. developed a method based on suspension electrolysis technology to directly leach LiCoO2 in the anode region while re-synthesizing LiCoO2 in the cathode region [Figure 17A][92]. This technique employed spent cathode material powders, derived from the crushed and mixed cathodes of various mobile phone batteries, containing elemental compositions of Co (46.50 wt%), Li (5.85 wt%), Mn (3.22 wt%),
Figure 17. (A) Flow diagram depicting the recovery process of LiCoO2 from discarded mobile phones. Impact of the (B) NH4HCO3 concentration, (C) (NH4)2SO3 concentration, (D) current, (E) temperature, (F) solid-to-liquid ratio, and (G) holding time on the leaching rates of lithium and cobalt, and the regeneration rate of LiCoO2. (A-G) Figures reprinted with permission from Ref.[84]. Copyright 2023 Elsevier[84].
Based on the re-synthesis mechanism of LiCoO2, Li et al. suggested regenerating LiCoO2 through controlled electrochemical deposition reactions[93]. Following the leaching of spent LiCoO2 with HNO3, a solution of
Figure 18. (A) Illustration of the re-synthesis mechanisms of LiCoO2. (B) Schematic showing the recycling instrument using electrochemical deposition. (C) Charge-discharge characteristics of the spent and regenerated LiCoO2 at a rate of 0.1 C. (D) Cyclic voltammogram of the LiCoO2 material at a scan rate of 5 mV/s. (E) Cycling performance of regenerated LiCoO2 at a rate of 0.1 C. (A-E) Figures reprinted with permission from Ref.[93]. Copyright 2011 Elsevier[93].
The initial capacities for charging and discharging of the regeneration LiCoO2 were 130.8 and 127.2 mAh/g, respectively, in contrast to the capacity of commercial LCO of 140 mAh/g, as illustrated in Figure 18C. After 30 cycles, the capacity degradation remained below 4%, with a charging efficiency of 99.1%, as shown in Figure 18E. This method directly regenerated the positive electrode material from the filtrate of spent LiCoO2. However, the electrochemical performance of the synthesized LiCoO2 did not meet that of its commercial counterpart. The recycling process necessitated high temperatures and prolonged reaction times, leading to increased energy consumption. Moreover, the use of platinum electrodes may be impractical for large-scale applications.
Materials synthesized through electrochemical recycling can be applied in electrochemical sensors, supercapacitors, pseudocapacitors, and catalysts. Gonçalves et al. utilized AISI 430 stainless steel as the substrate and the leachate of spent LIB cathode materials as the electrolyte to prepare cobalt-containing materials through potentiostatic electrolysis[94]. These materials were used as non-enzymatic electrochemical sensors for glucose detection. The sensor demonstrated a sensitivity of 70.2 μA/(mmol·cm²) within a linear range of 1-10 mmol/L, providing a novel approach for developing sensors from recycled materials.
COMPARISON OF THE VARIOUS RECYCLING PROCESS FOR SPENT LIBs
Table 2 compares different recycling methods. Generally, pyrometallurgy operates at high temperatures
Comparison of the various recovery processes for spent LIBs[98]
Method | Advantages | Disadvantages |
Pyrometallurgy | • No wastewater • Fewer processing steps • Direct melting allows recovery of metals as alloys | • Larger energy input required • Hazardous gases emissions • Li loss |
Hydrometallurgy | • High sustainability • High extraction efficiency • Low energy consumption • Little hazardous gas emission • Low capital cost | • Complex operation steps • A large quantity of waste • Hazardous gases emissions • Additional expense for disposal of the hazardous gases, acidic leachates, and acid wastewater |
Electrochemistry method | • Low operating cost • Minimal use of chemicals • Metal recovery rate is greater than 99% • No waste emissions | • The energy consumption in the process of separating the current collector and the cathode material is high (4.7 kwhkg-1) • The potentials of cobalt ions and nickel ions in the leachate are similar and cannot be separated by electrodeposition The electrochemical delithiation process is prone to side reactions, resulting in reduced current density and current efficiency (< 86%) • The electrochemical performance of the recycled cathode material is worse than that of the original cathode material |
By contrast, electrochemical techniques have broader applicability in the recycling of spent LIBs. These techniques utilize electron-mediated redox reactions instead of high-temperature roasting and chemical reagents as the reaction driving force, allowing reactions to proceed at lower temperatures and reagent concentrations. As a result, electrochemical methods offer advantages over traditional recycling methods in terms of process conditions and resource consumption. These methods also require relatively low electricity and reagent consumption, reducing costs, and generating non-toxic or -hazardous substances, leading to minimal waste and lower environmental costs. The metal recovery rate using electrochemical methods can exceed 99%, with high product quality, resulting in higher economic benefits. Although electrochemical regeneration methods offer low energy and reagent consumption, they cannot remove impurities from waste materials, leading to the inferior electrochemical performance of regenerated cathode materials compared to the original materials. Additionally, the regeneration method requires precise determination of lithium content in spent cathode materials to determine the necessary amount of lithium supplementation, making it less adaptable for raw materials and requiring stringent regeneration conditions, and hindering large-scale application.
CONCLUSION AND OUTLOOK
The growing global use of LIBs has led to a significant increase in their disposal, creating considerable environmental risks. As a result, the organic electrolytes and heavy metals contained in these materials will seep into the soil and water bodies, causing significant ecological damage. Additionally, these batteries serve as a source of valuable metals, such as Ni, Co, and Li, making their recycling a critical area of current research.
The advantages of pyrometallurgical recycling encompass its capability to process a broad spectrum of feedstocks, its high operational capacity, facile methodology, and the elimination of pre-treatment prerequisites. In developed nations, pyrometallurgy has emerged as the predominant technology for recycling spent LIBs, primarily attributed to the fact that recycling firms often do not bear the feedstock expenses and can levy disposal charges. Nonetheless, pyrometallurgical recycling is not without its disadvantages, which include substantial energy requirements, low metal recovery rates, rigorous equipment demands, and the need for additional alloy separation post-processing. Moreover, conventional pyrometallurgical approaches fail to recuperate lithium, leading to a loss in valuable lithium resources. To enhance the extraction and purification of valuable metal from spent LIBs, pyrometallurgy must be integrated with hydrometallurgical processes, thus compounding the complexity of the overall recycling methodology.
Compared to pyrometallurgy, hydrometallurgical recycling offers benefits such as increased efficiency, lower emissions of toxic gases, enhanced purity of the recovered metals or metal salts, and more moderate reaction conditions. Consequently, in China, by leveraging well-established metallurgical technologies and a robust hydrometallurgical industry, hydrometallurgy has emerged as the predominant technology for recycling spent LIBs. However, hydrometallurgical recycling processes are characterized by longer durations, higher chemical usage, and increased wastewater discharge, leading to greater environmental pollution.
The utilization of electrochemical techniques in recycling spent LIBs significantly differs from traditional pyrometallurgy and hydrometallurgy. This technology dramatically reduces the utilization of chemical reagents while improving the efficiency of element separation and recovery rates, showcasing considerable industrial applicability. During the preprocessing stage, applying voltage aids in separating active substances from the current collector, enabling the detachment of positive electrode materials and the recovery of intact, reusable aluminum/copper foils. Additionally, electrochemical-assisted leaching, driven by external current, can facilitate the efficient leaching of positive electrode materials while minimizing the need for chemical reagents in hydrometallurgical processes. Electrochemical deposition, by applying specific potentials, utilizes the differences in deposition potentials among various metal ions in the leaching solution to facilitate the targeted separation and recovery of valuable metals. Electrodialysis, which involves the selective movement of ions through a semi-permeable membrane under an electric field, allows for the selective separation of metal ions in the leaching solution. Importantly, electrochemical techniques can also regenerate cathode materials from spent LIBs. By applying an external voltage, lithium ions can be reintroduced into the cathode materials, compensating for lithium ion loss and achieving the direct regeneration of these materials.
In the process of recycling spent LIBs, electrochemical technology holds significant promise for future applications. Future research should mainly focus on the following aspects.
(1) Technical optimization and process improvement: Future development of electrochemical methods should prioritize optimizing process parameters to enhance recovery efficiency and metal purity. This includes improving electrode materials, optimizing electrolyte compositions, and fine-tuning operational conditions to achieve more efficient and stable metal recovery.
(2) Minimizing energy consumption and environmental impact: By utilizing clean energy sources (e.g., wind and solar power) to supply electricity, the carbon footprint of the electrochemical recovery process may be significantly reduced. Additionally, developing more efficient electrodes and electrochemical equipment to lower energy consumption and improve energy efficiency could serve as a key direction for future research.
(3) Multi-metal recovery and separation: Given the coexistence of multiple metals in spent LIBs, future development of electrochemical methods should focus on achieving the efficient separation and recovery of various metals. By adjusting electrochemical parameters, the selective separation of different metal ions may be realized, avoiding the use of complex chemical reagents and extractants and reducing environmental burden.
(4) Scale-up and industrial application: Currently, electrochemical recycling technology is primarily at the laboratory research stage. Future efforts should aim to scale these technologies for industrial application. This includes developing large-scale, efficient electrochemical recycling equipment and drawing on the successful experiences of other electrochemical industries, such as electroplating and electrodeposition, to drive the industrialization of this technology.
(5) Comprehensive utilization of waste and circular economy: Future electrochemical recycling methods should not only focus on metal recovery but also explore the comprehensive utilization of waste generated during the process. For example, by using by-products generated during recovery to produce new materials or directly applying recovered metals to manufacture new batteries or other functional materials, resource closed-loop recycling may be achieved, promoting the development of a circular economy.
(6) Interdisciplinary collaboration and innovation: The future development of electrochemical recycling technology should rely on collaborative innovation across disciplines such as chemistry, materials science, environmental science, and engineering. Through interdisciplinary cooperation, new electrode materials may be developed, innovative electrochemical reaction systems may be explored, and new recovery pathways can be identified, driving breakthrough advancements in the application of electrochemical methods in LIB recycling.
DECLARATIONS
Authors’ contributions
Conceptualization, investigation, visualization, writing original draft: Li M, Mo R, Guo F
Investigation, visualization: Zhang K, Ding A
Visualization, validation: Xiao C
Availability of data and materials
Not applicable.
Financial support and sponsorship
This work was supported by the Science and Technology Program of the Institute of Zhejiang University-Quzhou (No. IZQ2021KJ2036), the Research Funds of the Institute of Zhejiang University-Quzhou
Conflicts of interest
All authors declared that there are no conflicts of interest.
Ethical approval and consent to participate
Not applicable.
Consent for publication
Not applicable.
Copyright
© The Author(s) 2024.
REFERENCES
1. Hantanasirisakul K, Sawangphruk M. Sustainable reuse and recycling of spent Li-ion batteries from electric vehicles: chemical, environmental, and economical perspectives. Glob Chall 2023;7:2200212.
2. Fu Y, He Y, Qu L, et al. Enhancement in leaching process of lithium and cobalt from spent lithium-ion batteries using benzenesulfonic acid system. Waste Manag 2019;88:191-9.
3. Zhang X, Xie Y, Lin X, Li H, Cao H. An overview on the processes and technologies for recycling cathodic active materials from spent lithium-ion batteries. J Mater Cycles Waste Manag 2013;15:420-30.
4. Ordoñez J, Gago E, Girard A. Processes and technologies for the recycling and recovery of spent lithium-ion batteries. Renew Sustain Energy Rev 2016;60:195-205.
5. Zhou L, Zhang K, Hu Z, et al. Recent developments on and prospects for electrode materials with hierarchical structures for lithium-ion batteries. Adv Energy Mater 2018;8:1701415.
6. evtank.cn. Beijing: China YiWei institute of economics; c2024. Available from: http://www.evtank.cn/DownloadDetail.aspx?ID=547 [Last accessed on 18 Jul 2024].
7. itdcw.com. Beijing: battery network; c2023. Available from: https://www.itdcw.com/news/hangyebaogao/011G332922023.html [Last accessed on 18 Jul 2024].
8. Natarajan S, Aravindan V. Burgeoning prospects of spent lithium-ion batteries in multifarious applications. Adv Energy Mater 2018;8:1802303.
9. Fan E, Li L, Wang Z, et al. Sustainable recycling technology for Li-ion batteries and beyond: challenges and future prospects. Chem Rev 2020;120:7020-63.
10. recellcenter.org. Chicago: U.S. Department of energy office of science, UChicago Argonne LLC. Available from: https://recellcenter.org/research [Last accessed on 18 Jul 2024].
11. Hou J, Yang M, Wang D, Zhang J. Fundamentals and challenges of lithium ion batteries at temperatures between -40 and 60 °C. Adv Energy Mater 2020;10:1904152.
12. Arshad F, Li L, Amin K, et al. A comprehensive review of the advancement in recycling the anode and electrolyte from spent lithium ion batteries. ACS Sustain Chem Eng 2020;8:13527-54.
13. Liu W, Li X, Xiong D, et al. Significantly improving cycling performance of cathodes in lithium ion batteries: the effect of Al2O3 and LiAlO2 coatings on LiNi0.6Co0.2Mn0.2O2. Nano Energy 2018;44:111-20.
14. Kretschmer K, Sun B, Su D, Zhao Y, Wang G. Scalable preparation of LiFePO4/C nanocomposites with sp2 -coordinated carbon coating as high-performance cathode materials for lithium-ion batteries. ChemElectroChem 2015;2:2096-103.
15. Yuan L, Wang Z, Zhang W, et al. Development and challenges of LiFePO4 cathode material for lithium-ion batteries. Energy Environ Sci 2011;4:269-84.
16. Okubo M, Hosono E, Kim J, et al. Nanosize effect on high-rate Li-ion intercalation in LiCoO2 electrode. J Am Chem Soc 2007;129:7444-52.
17. Luo F, Wei C, Zhang C, et al. Operando X-ray diffraction analysis of the degradation mechanisms of a spinel LiMn2O4 cathode in different voltage windows. J Energy Chem 2020;44:138-46.
18. Xia S, Huang W, Shen X, et al. Rearrangement on surface structures by boride to enhanced cycle stability for LiNi0.80Co0.15Al0.05O2 cathode in lithium ion batteries. J Energy Chem 2020;45:110-8.
19. Li P, Luo S, Zhang L, et al. Progress, challenges, and prospects of spent lithium-ion batteries recycling: a review. J Energy Chem 2024;89:144-71.
20. Xue Y, Wang Y. Green electrochemical redox mediation for valuable metal extraction and recycling from industrial waste. Green Chem 2020;22:6288-309.
21. Kim K, Candeago R, Rim G, Raymond D, Park AA, Su X. Electrochemical approaches for selective recovery of critical elements in hydrometallurgical processes of complex feedstocks. iScience 2021;24:102374.
22. Du K, Ang EH, Wu X, Liu Y. Progresses in sustainable recycling technology of spent lithium-ion batteries. Energy Environ Mater 2022;5:1012-36.
23. Chen M, Ma X, Chen B, et al. Recycling end-of-life electric vehicle lithium-ion batteries. Joule 2019;3:2622-46.
24. tatista.com. Average lithium carbonate price from 2010 to 2023, Available from: https://www.statista.com/statistics/606350/battery-grade-lithium-carbonate-price/ [Last accessed on 18 Jul 2024].
26. Mrozik W, Rajaeifar MA, Heidrich O, Christensen P. Environmental impacts, pollution sources and pathways of spent lithium-ion batteries. Energy Environ Sci 2021;14:6099-121.
27. Chan KH, Anawati J, Malik M, Azimi G. Closed-loop recycling of lithium, cobalt, nickel, and manganese from waste lithium-ion batteries of electric vehicles. ACS Sustain Chem Eng 2021;9:4398-410.
28. Lisbona D, Snee T. A review of hazards associated with primary lithium and lithium-ion batteries. Process Saf Environ 2011;89:434-42.
29. Miao Y, Liu L, Xu K, Li J. High concentration from resources to market heightens risk for power lithium-ion battery supply chains globally. Environ Sci Pollut Res Int 2023;30:65558-71.
30. Harper G, Sommerville R, Kendrick E, et al. Recycling lithium-ion batteries from electric vehicles. Nature 2019;575:75-86.
31. Larcher D, Tarascon JM. Towards greener and more sustainable batteries for electrical energy storage. Nat Chem 2015;7:19-29.
32. Meshram P, Pandey B, Mankhand T. Extraction of lithium from primary and secondary sources by pre-treatment, leaching and separation: a comprehensive review. Hydrometallurgy 2014;150:192-208.
33. Wang Y, An N, Wen L, et al. Recent progress on the recycling technology of Li-ion batteries. J Energy Chem 2021;55:391-419.
34. Li L, Zhang X, Li M, et al. The recycling of spent lithium-ion batteries: a review of current processes and technologies. Electrochem Energ Rev 2018;1:461-82.
35. Shi Y, Zhang M, Meng YS, Chen Z. Ambient-pressure relithiation of degraded LixNi0.5Co0.2Mn0.3O2 (0 < x < 1) via eutectic solutions for direct regeneration of lithium-ion battery cathodes. Adv Energy Mater 2019;9:1900454.
36. Lai Y, Zhu X, Li J, et al. Efficient recovery of valuable metals from cathode materials of spent LiCoO2 batteries via co-pyrolysis with cheap carbonaceous materials. Waste Manag 2022;148:12-21.
37. Li J, Lai Y, Zhu X, et al. Pyrolysis kinetics and reaction mechanism of the electrode materials during the spent LiCoO2 batteries recovery process. J Hazard Mater 2020;398:122955.
38. Baum ZJ, Bird RE, Yu X, Ma J. Lithium-ion battery recycling - overview of techniques and trends. ACS Energy Lett 2022;7:712-9.
39. Zhou M, Li B, Li J, Xu Z. Pyrometallurgical technology in the recycling of a spent lithium ion battery: evolution and the challenge. ACS EST Eng 2021;1:1369-82.
40. Makuza B, Tian Q, Guo X, Chattopadhyay K, Yu D. Pyrometallurgical options for recycling spent lithium-ion batteries: a comprehensive review. J Power Sources 2021;491:229622.
41. Rombach E, Friedrich B. Chapter 10 - recycling of rare metals. In: Worrell E, Reuter MA, editors. Handbook of recycling. Amsterdam: Elsevier; 2014. pp. 125-50.
42. Xu P, Tan DH, Gao H, Rose S, Chen Z. Recycling of Li-ion batteries for electric vehicles. In: Cabeza LF, editor. Encyclopedia of energy storage. Amsterdam: Elsevier; 2022. pp. 98-107.
43. Zhang Y, Wang W, Fang Q, Xu S. Improved recovery of valuable metals from spent lithium-ion batteries by efficient reduction roasting and facile acid leaching. Waste Manag 2020;102:847-55.
44. Yan Z, Sattar A, Li Z. Priority lithium recovery from spent Li-ion batteries via carbothermal reduction with water leaching. Resour Conserv Recy 2023;192:106937.
45. Zheng R, Zhao L, Wang W, et al. Optimized Li and Fe recovery from spent lithium-ion batteries via a solution-precipitation method. RSC Adv 2016;6:43613-25.
46. Chen X, Ma H, Luo C, Zhou T. Recovery of valuable metals from waste cathode materials of spent lithium-ion batteries using mild phosphoric acid. J Hazard Mater 2017;326:77-86.
47. Li J, Shi P, Wang Z, Chen Y, Chang CC. A combined recovery process of metals in spent lithium-ion batteries. Chemosphere 2009;77:1132-6.
48. Zhu S, He W, Li G, Zhou X, Zhang X, Huang J. Recovery of Co and Li from spent lithium-ion batteries by combination method of acid leaching and chemical precipitation. T Nonferr Metal Soc 2012;22:2274-81.
49. Jha MK, Kumari A, Jha AK, Kumar V, Hait J, Pandey BD. Recovery of lithium and cobalt from waste lithium ion batteries of mobile phone. Waste Manag 2013;33:1890-7.
50. Bertuol DA, Machado CM, Silva ML, Calgaro CO, Dotto GL, Tanabe EH. Recovery of cobalt from spent lithium-ion batteries using supercritical carbon dioxide extraction. Waste Manag 2016;51:245-51.
51. Lee CK, Rhee K. Reductive leaching of cathodic active materials from lithium ion battery wastes. Hydrometallurgy 2003;68:5-10.
52. Meshram P, Pandey BD, Mankhand TR. Recovery of valuable metals from cathodic active material of spent lithium ion batteries: leaching and kinetic aspects. Waste Manag 2015;45:306-13.
53. Meshram P, Abhilash, Pandey BD, Mankhand TR, Deveci H. Comparison of different reductants in leaching of spent lithium ion batteries. JOM 2016; 68:2613-2623.
54. Wang R, Lin Y, Wu S. A novel recovery process of metal values from the cathode active materials of the lithium-ion secondary batteries. Hydrometallurgy 2009;99:194-201.
55. Li L, Qu W, Zhang X, et al. Succinic acid-based leaching system: a sustainable process for recovery of valuable metals from spent
56. Li L, Lu J, Ren Y, et al. Ascorbic-acid-assisted recovery of cobalt and lithium from spent Li-ion batteries. J Power Sources 2012;218:21-7.
57. Li L, Ge J, Wu F, Chen R, Chen S, Wu B. Recovery of cobalt and lithium from spent lithium ion batteries using organic citric acid as leachant. J Hazard Mater 2010;176:288-93.
58. Sun L, Qiu K. Organic oxalate as leachant and precipitant for the recovery of valuable metals from spent lithium-ion batteries. Waste Manag 2012;32:1575-82.
59. Li L, Dunn JB, Zhang XX, et al. Recovery of metals from spent lithium-ion batteries with organic acids as leaching reagents and environmental assessment. J Power Sources 2013;233:180-9.
60. Sun C, Xu L, Chen X, Qiu T, Zhou T. Sustainable recovery of valuable metals from spent lithium-ion batteries using DL-malic acid: Leaching and kinetics aspect. Waste Manag Res 2018;36:113-20.
61. Li L, Bian Y, Zhang X, et al. Economical recycling process for spent lithium-ion batteries and macro- and micro-scale mechanistic study. J Power Sources 2018;377:70-9.
62. Yao L, Feng Y, Xi G. A new method for the synthesis of LiNi1/3Co1/3Mn1/3O2 from waste lithium ion batteries. RSC Adv 2015;5:44107-14.
63. Li L, Bian Y, Zhang X, et al. Process for recycling mixed-cathode materials from spent lithium-ion batteries and kinetics of leaching. Waste Manag 2018;71:362-71.
64. Feng Y, Yang L, Liu J, Logan BE. Electrochemical technologies for wastewater treatment and resource reclamation. Environ Sci Wat Res 2016;2:800-31.
65. Wang M, Tan Q, Chiang JF, Li J. Recovery of rare and precious metals from urban mines - a review. Front Environ Sci Eng 2017;11:1-17.
66. Ambaye TG, Vaccari M, Castro FD, Prasad S, Rtimi S. Emerging technologies for the recovery of rare earth elements (REEs) from the end-of-life electronic wastes: a review on progress, challenges, and perspectives. Environ Sci Pollut Res Int 2020;27:36052-74.
67. Kim S, Lee J, Kim S, Kim S, Yoon J. Electrochemical lithium recovery with a LiMn2O4-zinc battery system using zinc as a negative electrode. Energy Tech 2018;6:340-4.
68. Calvo EJ. Electrochemical methods for sustainable recovery of lithium from natural brines and battery recycling. Curr Opin Electroche 2019;15:102-8.
69. Zhou G, Chen L, Chao Y, Li X, Luo G, Zhu W. Progress in electrochemical lithium ion pumping for lithium recovery. J Energy Chem 2021;59:431-45.
70. Petersen HA, Myren THT, O’sullivan SJ, Luca OR. Electrochemical methods for materials recycling. Mater Adv 2021;2:1113-38.
71. Bi H, Zhu H, Zu L, Bai Y, Gao S, Gao Y. A new model of trajectory in eddy current separation for recovering spent lithium iron phosphate batteries. Waste Manag 2019;100:1-9.
72. Wang F, Zhang T, He Y, et al. Recovery of valuable materials from spent lithium-ion batteries by mechanical separation and thermal treatment. J Clean Prod 2018;185:646-52.
73. Guo Y, Li F, Zhu H, Li G, Huang J, He W. Leaching lithium from the anode electrode materials of spent lithium-ion batteries by hydrochloric acid (HCl). Waste Manag 2016;51:227-33.
74. Contestabile M, Panero S, Scrosati B. A laboratory-scale lithium-ion battery recycling process. J Power Sources 2001;92:65-9.
75. Cao N, Zhang Y, Chen L, et al. An innovative approach to recover anode from spent lithium-ion battery. J Power Sources 2021;483:229163.
76. Chu W, Zhang Y, Chen L, Wu K, Huang Y, Jia Y. Comprehensive recycling of Al foil and active materials from the spent lithium-ion battery. Sep Purif Technol 2021;269:118704.
77. Lei S, Zhang Y, Song S, et al. Strengthening valuable metal recovery from spent lithium-ion batteries by environmentally friendly reductive thermal treatment and electrochemical leaching. ACS Sustain Chem Eng 2021;9:7053-62.
78. Diaz LA, Strauss ML, Adhikari B, Klaehn JR, Mcnally JS, Lister TE. Electrochemical-assisted leaching of active materials from lithium ion batteries. Resour Conserv Recy 2020;161:104900.
79. Prabaharan G, Barik SP, Kumar N, Kumar L. Electrochemical process for electrode material of spent lithium ion batteries. Waste Manag 2017;68:527-33.
80. Freitas M, Celante V, Pietre M. Electrochemical recovery of cobalt and copper from spent Li-ion batteries as multilayer deposits. J Power Sources 2010;195:3309-15.
81. Freitas M, Garcia E. Electrochemical recycling of cobalt from cathodes of spent lithium-ion batteries. J Power Sources 2007;171:953-9.
82. Freitas MBJG, Garcia EM, Celante VG. Electrochemical and structural characterization of cobalt recycled from cathodes of spent Li-ion batteries. J Appl Electrochem 2009;39:601-7.
83. Peng F, Mu D, Li R, et al. Impurity removal with highly selective and efficient methods and the recycling of transition metals from spent lithium-ion batteries. RSC Adv 2019;9:21922-30.
84. Iizuka A, Yamashita Y, Nagasawa H, Yamasaki A, Yanagisawa Y. Separation of lithium and cobalt from waste lithium-ion batteries via bipolar membrane electrodialysis coupled with chelation. Sep Purif Technol 2013;113:33-41.
85. Li X, Liu S, Yang J, He Z, Zheng J, Li Y. Electrochemical methods contribute to the recycling and regeneration path of lithium-ion batteries. Energy Stor Mater 2023;55:606-30.
86. Chan KH, Malik M, Azimi G. Separation of lithium, nickel, manganese, and cobalt from waste lithium-ion batteries using electrodialysis. Resour Conserv Recy 2022;178:106076.
87. Li Z, He L, Zhao ZW, Wang D, Xu W. Recovery of lithium and manganese from scrap LiMn2O4 by slurry electrolysis. ACS Sustain Chem Eng 2019;7:16738-46.
88. Li Z, Liu D, Xiong J, He L, Zhao Z, Wang D. Selective recovery of lithium and iron phosphate/carbon from spent lithium iron phosphate cathode material by anionic membrane slurry electrolysis. Waste Manag 2020;107:1-8.
89. Li Z, He L, Zhu Y, Yang C. A green and cost-effective method for production of LiOH from spent LiFePO4. ACS Sustain Chem Eng 2020;8:15915-26.
90. Zhang L, Xu Z, He Z. Electrochemical relithiation for direct regeneration of LiCoO2 materials from spent lithium-ion battery electrodes. ACS Sustain Chem Eng 2020;8:11596-605.
91. Yang T, Lu Y, Li L, et al. An effective relithiation process for recycling lithium-ion battery cathode materials. Adv Sustain Syst 2020;4:1900088.
92. Wang J, Lv J, Zhang M, et al. Recycling lithium cobalt oxide from its spent batteries: an electrochemical approach combining extraction and synthesis. J Hazard Mater 2021;405:124211.
93. Li L, Chen R, Sun F, Wu F, Liu J. Preparation of LiCoO2 films from spent lithium-ion batteries by a combined recycling process. Hydrometallurgy 2011;108:220-5.
94. Gonçalves SA, Garcia EM, Taroco HA, et al. Development of non-enzymatic glucose sensor using recycled cobalt from cell phone
95. Barbieri EMS, Lima EPC, Lelis MFF, Freitas MBJG. Recycling of cobalt from spent Li-ion batteries as β-Co (OH)2 and the application of Co3O4 as a pseudocapacitor. J Power Sources 2014;270:158-65.
96. Aboelazm EAA, Ali GAM, Algarni H, Yin H, Zhong YL, Chong FK. Magnetic electrodeposition of the hierarchical cobalt oxide nanostructure from spent lithium-ion batteries: its application as a supercapacitor electrode. J Phys Chem C 2018;122:12200-206.
97. Falqueto JB, Magnago LB, Rocha AKS, et al. Photocatalytic properties of Co/Co3O4 films recycled from spent Li-ion batteries. Ionics 2018;24:2167-73.
Cite This Article
Export citation file: BibTeX | EndNote | RIS
OAE Style
Li M, Mo R, Ding A, Zhang K, Guo F, Xiao C. Electrochemical technology to drive spent lithium-ion batteries (LIBs) recycling: recent progress, and prospects. Energy Mater 2024;4:400070. http://dx.doi.org/10.20517/energymater.2024.29
AMA Style
Li M, Mo R, Ding A, Zhang K, Guo F, Xiao C. Electrochemical technology to drive spent lithium-ion batteries (LIBs) recycling: recent progress, and prospects. Energy Materials. 2024; 4(6):400070. http://dx.doi.org/10.20517/energymater.2024.29
Chicago/Turabian Style
Li, Ming, Fan Guo, and Chengliang Xiao. 2024. "Electrochemical technology to drive spent lithium-ion batteries (LIBs) recycling: recent progress, and prospects" Energy Materials. 4, no.6: 400070. http://dx.doi.org/10.20517/energymater.2024.29
ACS Style
Li, M.; Mo R.; Ding A.; Zhang K.; Guo F.; Xiao C. Electrochemical technology to drive spent lithium-ion batteries (LIBs) recycling: recent progress, and prospects. Energy. Mater. 2024, 4, 400070. http://dx.doi.org/10.20517/energymater.2024.29
About This Article
Special Issue
Copyright
Data & Comments
Data
![](https://g.oaes.cc/oae/nuxt/img/like.08d1ca4.png)
Comments
Comments must be written in English. Spam, offensive content, impersonation, and private information will not be permitted. If any comment is reported and identified as inappropriate content by OAE staff, the comment will be removed without notice. If you have any queries or need any help, please contact us at support@oaepublish.com.