In Situ Tuning Residual Lithium Compounds And Constructing Tio2 Coating For Surface Modification Of A Nickel-Rich Cathode Toward High-Energy Lithium-Ion Batteries

Nickel-rich layered oxides with excellent specific capacity and reasonable cost have extensively employed as cathode materials for higher energy density lithium-ion batteries (LIBs). However, side reactions caused by the surface contaminations and deterioration of the layered structure especially at high cutoff voltage lead to insufficient cycle life and poor electrochemical performance, which further hinder the commercial development of nickel-rich cathode materials. Herein, an optimized route combining acid treatment with titanium dioxide (TiO2) coating successfully modifies the surface of the single-crystalline LiNi0.6Co0.2Mn0.2O2 (SC-NCM) cathode material, which collaboratively eliminates surface residual contaminations and stabilizes the bulk structure. Furthermore, the evolution of the internal crack, phase transition, and host structure can be effectively mitigated via applying the TiO2 coating on SC-NCM even after long-term cycling. Moreover, it is confirmed that such surface treatment significantly impedes the conversion of surface residual lithium after air exposure. As the cathode material for LIBs, as-optimized SC-NCM delivers a capacity retention of 87.4% at 1 C over 200 cycles at room temperature, higher than that of pristine SC-NCM (a capacity retention of 73.5%). This proposed method provides a simple and available strategy to obtain prolonged service life and safety characteristics of LIBs.