Ultrastable solid-state LiNi0.8Co0.1Mn0.1O2/Li battery by suppressed defluorination reaction and in situ passivation on electrodes

In addition to the Li + transport kinetics, the interface stability of the solid-state electrolyte is also critical for solid-state Li-metal batteries (SLMBs), especially for nickel-rich cathode-based ones. Herein, we develop an air-processable composite polymer electrolyte (CPE) using polyvinylidene difluoride (PVDF) as matrix, LiCF 3 SO 3 as Li-salt, Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 as fast Li-conductor and C 4 BLiO 8 (LiBOB) as additive. The presence of LiBOB suppress the defluorination reaction of PVDF in electrolyte solution , that reduce the corrosion reaction on LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) particles and enhance the intermolecular interactions between [Li(DMF) x ] + and PVDF as well. Importantly, the formed H 3 BO 3 in CPE induce the in situ passivation of Li-B-O/B-O on surface of NCM811 and Li-metal, which impedes the crack of NCM811 particles and growth of Li-dendrites. Thus, NCM811/Li battery exhibits a high specific capacity up to 196.1 mAh g −1 (0.1C) and excellent long-term stability. Specifically, a capacity retention rate of 71.8 % (134.5/181.1 mAh g −1 ) and 78.7 % (132.1/167.9 mAh g −1 ) has been achieved at 0.2C and 0.5C after 500 cycles, respectively, which represent one of the best performances in the field. This strategy also greatly enhance the cyclic stability of LiFePO 4 /Li battery, which shows a capacity retention rate of 92 % (143.5 mAh g −1 ) after 700 cycles.