Polycrystalline Li‐Rich Mn‐Based Cathodes for All Solid‐State Batteries

High-capacity Li-rich Mn-based oxide cathode (LRMO) materials are promising candidates for all-solid-state batteries (ASSBs). While single-crystal materials have been widely regarded as a promising strategy to enhance cycling stability in ASSBs, the potential of commercialized polycrystalline Li-rich Mn-based cathodes (PC-LRMO) remains largely unexplored. Herein, we propose a simple but effective strategy to pre-construct a stabilized, organic-rich cathode electrolyte interface (CEI) both on the surface of PC-LRMO cathodes and at the grain boundaries (GBs) of the secondary particles. This organic-rich CEI facilitates low interfacial impedance and fast interfacial ion transfer kinetics. Consequently, this enhanced interfacial ion transport alleviates polarization under high-temperature operating conditions, thereby improving the discharge specific capacity of a working battery. Furthermore, the organic-rich CEI effectively mitigates direct contact and facilitates the formation of a self-adaptive interface between the high-voltage cathodes and the solid electrolytes. This adaptive interface alleviates stress and strain during charge-discharge cycling, suppresses detrimental side reactions and voltage decay, and stabilizes the high-voltage interface. Therefore, an improved rate capability and long-term cycling stability of the LRMO cathode is achieved. This facile solution-based preparation strategy provides an economically viable approach for effective utilization of emerging cathodes for ASSBs.