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 LiCoO2 cathode was greatly improved via coating LiCoO2 with high-voltage stable Li3AlF6.At the upper cutoff voltage of 4.2 V, the poor electrochemical performance is mainly originated from the structure collapse of LiCoO2 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.