Investigations on the Fundamental Process of Cathode Electrolyte Interphase Formation and Evolution of High-Voltage Cathodes

(LNMO). The influences of crystal structure, chemical constitution and cut-off voltage on CEI composition are clarified. Among these cathodes, the spinel cathode exhibits the most stable CEI layer throughout the battery cycle. While the layered cathodes based on the 4d transition metal Ru favor CEI formation upon contacting the electrolyte. Most importantly, anionic redox reaction (ARR) activation at high voltages is verified to dominate CEI evolution in subsequent cycles. The distinct CEI behaviors in diverse cathodes can be attributed to a series of entangled processes, including electrolyte/Li salt decomposition, CEI component dissociation and dissociated CEI species redeposition. Based on these findings, rational guidelines are provided for the interface design of high-voltage LIBs.