Optimized layered ternary LiNi0.5Co0.2Mn0.3O2 cathode materials modified with ultrathin Li3InCl6 fast ion conductor layer for lithium-ion batteries

LiNi0.5Co0.2Mn0.3O2 (NCM523) powders modified with fast ion conductor Li3InCl6 (LIC) are fabricated via sol-gel and sintering processes, and the LIC layer with a thickness of about 2.4842 nm is uniformly covered on the surface to fabricate the targeted LIC@NCM523-2 composite powders, in which the LIC layer not only lowers the residual lithium content but also decreases the cation mixing degree. The LIC@NCM523-2 electrode preserves relatively intact morphology and layered structure after cycles. Moreover, the LIC@NCM523-2 electrode delivers discharge specific capacity of 130.5 mAh g−1 with capacity retention ratio of 76.8% after 200 cycles at 1.0 C and 25 °C, and retains about 108.8 mAh g−1 at the 200th cycle at 1.0 C and 60 °C. Importantly, the LIC@NCM523-2 electrode exhibits desirable discharge specific capacity of 128.2 mAh g−1 at 5.0 C and easily returns back to 164.3 mAh g−1 at 0.1 C and 25 °C. Those outstanding electrochemical properties are ascribed to the fact that the appropriate thickness LIC layer protects active particles from the corrosion of liquid electrolytes to stabilize the internal structure and provides high conductivity to facilitate Li+ ions transport, elucidating the importance of the surface modified strategy with the fast ion conductor LIC layer.