Advancements in lithium solid polymer batteries: surface modification, in-situ/operando characterization, and simulation methodologies

The interest in lithium solid-state batteries (LSSBs) is rapidly escalating, driven by their impressive energy density and safety features. However, they face crucial challenges, including limited ionic conductivity, high interfacial resistance, and unwanted side reactions. Intensive research has been conducted on polymer solid-state electrolytes positioned between the anode and cathode, aiming to replace traditional liquid electrolytes. To alleviate interfacial resistances and mitigate adverse reactions between electrodes and polymer electrolytes, the interfacial modification strategy has been proven to enhance the energy density of LSSBs. This design process is grounded in precise and elaborate theories, with in-situ/operando techniques and simulation methods facilitating the interpretation and validation of structure-property relationships by simplifying them. This review first outlines the recent advancements in surface modification strategies specifically tailored for solid polymer electrolytes. Furthermore, it also provides an overview of innovative in-situ/operando characterizations and simulation methods featured in recent publications, which can gain a more accurate understanding of processes that occur within materials, devices, or chemical reactions as they are happening. Lastly, the review discusses the existing challenges and presents a forward-looking perspective on the future of the next-generation LSSBs.