fig15

Figure 15. (A) Different electrochemical redox couples judged by regulating the voltage range. Charge-discharge curves (i) and corresponding dQ/dV (ii) by fixing the lower cut-off voltage and gradually increasing the upper cut-off voltage. Charge-discharge curves (iii) and corresponding dQ/dV (iv) by fixing the upper cut-off voltage and gradually decreasing the lower cut-off voltage^[199]. (B) CV curves of different LRMO materials at different scanning rates and the linear fit of the i_p and v^1/2 in the illustration^[201]. (i) Li[Li_0.31Mn_0.65Ni_0.02Co_0.02]O₂; (ii) Li[Li_0.27Mn_0.63Ni_0.05Co_0.05]O₂; (iii) Li[Li_0.2Mn_0.6Ni_0.1Co_0.1]O₂; (iv) Li[Li_0.11Mn_0.55Ni_0.17Co_0.17]O₂. (C) (i) EIS Nyquist plots of the tested LRMO materials with the corresponding equivalent circuit. (ii) Linear relationship between Z′ and ω(angular frequency)^-1/2 in the low-frequency region with σ (the slopes of the simulated lines)^[201]. (D) Overall GITT curve (i) for Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ during the initial charge and discharge with the (ii) schematic diagram in a single GITT titration curve^[110]. CV: Cyclic voltammetry; LRMO: lithium-rich manganese-based layered oxide; EIS: electrochemical impedance spectroscopy; GITT: galvanostatic intermittent titration technique.