Single crystal Ni-rich layered cathodes enabling superior performance in all-solid-state batteries with PEO-based solid electrolytes

PEO-based composite electrolytes are one of the most practical electrolytes in all-solid batteries (ASSBs). To achieve the perspective of ASSBs with high energy density, PEO based composite electrolytes should match high-voltage cathodes, but the stability of cathode interface is a challenging issue. Herein, we investigate the electrochemical performance of single-crystal LiNi0.6Mn0.1Co0.3O2 (SC-NMC613) in ASSBs with PEO-based electrolytes, and compared the electrochemical performance of SC-NMC613 with conventional polycrystalline LiNi0.6Mn0.1Co0.3O2 (PC-NMC613) systematically. The Li+ diffusion coefficient of SC-NMC613 is 2-4 times higher than that of PC-NCM613 in ASSBs. SC-NCM613 shows high initial specific capacity (152 mAh•g−1) at 0.5 C, stable cycling performance (100 cycles, retention of 108.9 mAh•g−1), and exceptional rate capability even without surface modification, while PC-NCM613 shows low initial specific capacity (137.5 mAh•g−1) at 0.5 C, poor cycling performance (100 cycles, retention of 90.1 mAh•g−1), and poor rate capability in ASSBs. The severe cycling degradation of the PC-NCM613 is mainly attributed to the structural deterioration inside particles and the formation of rock-salt phase. The SC-NCM613 particles observably alleviate the generation of intergranular cracks and decelerate the formation of rock-salt phase. SC-NCM cathodes in ASSBs with PEO-based electrolyte are beneficial to the stability of cathode interface. Therefore, developing single-crystal Ni-rich cathodes represents a promising strategy for both high energy density and power density of ASSBs.