Surface Construction of a High-Ionic-Conductivity Buffering Layer on a LiNi0.6Co0.2Mn0.2O2 Cathode for Stable All-Solid-State Sulfide-Based Batteries

Sulfide electrolyte-based all-solid-state batteries (ASSLBs) have been considered the most promising candidate for next-generation energy storage systems owing to the high ionic conductivity and soft nature of sulfide electrolytes. However, the inevitable side reactions between sulfide electrolytes and high-voltage cathode materials hinder their further application. Herein, we construct a robust and low-cost Li3PO4 (LPO) buffering layer on the surface of the NCM622 particles through a facile solution method. This strategy promotes the diffusion of lithium ions at the interface and significantly reduces the growth of battery polarization during the cycles by suppressing the side reactions between electrolytes and cathode materials. The assembled ASSLBs employing the LPO-NCM622 cathode exhibited superior cycling and rate performance compared with their counterpart, delivering high capacity of 177−1 and maintaining 79.2% of initial capacity after 100 cycles. Meanwhile, encouraging specific capacity of 75 mAh g−1 was reached at 1 C.