Insights Into the Interfacial Degradation of High-Voltage All-Solid-State Lithium Batteries

The cycle performance of poly(ethylene oxide) (PEO)-based all-solid-state lithium batteries with LiCoO 2 cathode was greatly improved via coating LiCoO 2 with high-voltage stable Li 3 AlF 6 . At the upper cutoff voltage of 4.2 V, the poor electrochemical performance is mainly originated from the structure collapse of LiCoO 2 at the surface instead of the decomposition of PEO. When the voltage reaches 4.5 V or even higher potentials, the intensive electrochemical decomposition of PEO-based solid polymer electrolyte accelerated interfacial degradation.