Dual-modification of Ni-rich cathode materials through strontium titanate coating and thermal treatment

Ni-rich layered structure ternary oxides, such as LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811), are promising cathode materials for high-energy lithium-ion batteries (LIBs). However, a trade-off between high capacity and long cycle life still obstructs the commercialization of Ni-rich cathodes in modern LIBs. Herein, a facile dual modification approach for improving the electrochemical performance of NCM811 was enabled by a typical perovskite oxide: strontium titanate (SrTiO₃). With a suitable thermal treatment, the modified cathode exhibited an outstanding electrochemical performance that could deliver a high discharge capacity of 188.5 mAh/g after 200 cycles under 1C with a capacity retention of 90%. The SrTiO₃ (STO) protective layer can effectively suppress the side reaction between the NCM811 and the electrolyte. In the meantime, the pillar effect provided by interfacial Ti doping could effectively reduce the Li⁺/Ni²⁺ mixing ratio on the NCM811 surface and offer more efficient Li⁺ migration between the cathode and the coating layer after post-thermal treatment (≥600 °C). This dual modification strategy not only significantly improves the structural stability of Ni-rich layered structure but also enhances the electrochemical kinetics via increasing diffusion rate of Li⁺. The electrochemical measurement results further disclosed that the 3 wt% STO coated NCM811 with 600 °C annealing exhibits the best performance compared with other control samples, suggesting an appropriate temperature range for STO coated NCM811 cathode is critical for maintaining a stable structure for the whole system. This work may offer an effective option to enhance the electrochemical performance of Ni-rich cathodes for high-performance LIBs.