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

Dual modification enabled by a thermally treated STO layer served multiple beneficial functions: 1) it prevented direct contact between the Ni-rich cathode and the organic electrolyte, thereby minimizing side reactions and enlarging the cathode lifespan; 2) it improved Li+ conductivity by defining clear Li-ion diffusion pathways, leading to low interfacial resistance and excellent electrochemical performance. [Display omitted] • Dual modifications are achieved with optimized thermal treatment of SrTiO 3 coated Ni-rich cathode material. • The specific capacity, cyclic stability and rate performance of Ni-rich cathode materials are significantly improved. • The SrTiO 3 coating not only protects NCM811 from parasitic reactions and facilitates Li+ diffusion enabled by the Ti interfacial doping. • The electrochemical polarization and internal cracking are reduced with the dual modification. Ni-rich layered structure ternary oxides, such as LiNi 0.8 Co 0.1 Mn 0.1 O 2 (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 (SrTiO 3). 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 SrTiO 3 (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. [ABSTRACT FROM AUTHOR]