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In this work, STO-coated NCM811 cathode materials were obtained through a facile wet chemical method, exhibiting excellent cyclic stability. Additionally, the STO-coated NCM811 could also mitigate the Li 2 CO 3 generation on the cathode surface by effective isolation from H 2 O and CO 2. Thus, higher specific capacity was retained after long-term storage in the air compared to the uncoated NCM811 sample. Our studies proposed an effective surface modification strategy to enhance the electrochemical performance of layered ternary oxides for high performance-cathodes in commercial LIBs. [Display omitted] Ni-rich layered 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. However, the relatively high reactivity of Ni in NCM811 cathodes results in severe capacity fading originating from the undesired side reactions that occur at the cathode-electrolyte interface during prolonged cycling. Therefore, the trade-off between high capacity and long cycle life can obstruct the commercialization process of Ni-rich cathodes in modern lithium-ion batteries (LIBs). In addition, high sensitivity toward air upon storage greatly limits the commercial application. Herein, a facile surface modification strategy is introduced to enhance the cycling and in-air storage stability of NCM811. The NCM811 with a uniform SrTiO 3 (STO) nano-coating layer exhibited outstanding electrochemical performances that could deliver a high discharge capacity of 173.5 mAh⋅g−1 after 200 cycles under 1C with a capacity retention of 90%. In contrast, the uncoated NCM811 only provided 65% capacity retention of 130.8 mAh⋅g−1 under the same conditions. Structural evolution analysis suggested that the STO coating acted as a buffer layer to suppress the dissolution of transition metal ions caused by the HF attack from the electrolyte and promote the lithium diffusion during the charge–discharge process. In addition, the constructed STO layer prevented the exposure of NCM811 to H 2 O and CO 2 and thus effectively improved the in-air storage stability. This work offers an effective way to enhance the performance stability of Ni-rich oxides for high-performance cathodes of lithium-ion batteries. [ABSTRACT FROM AUTHOR]

In this work, STO-coated NCM811 cathode materials were obtained through a facile wet chemical method, exhibiting excellent cyclic stability. Additionally, the STO-coated NCM811 could also mitigate the Li 2 CO 3 generation on the cathode surface by effective isolation from H 2 O and CO 2. Thus, higher specific capacity was retained after long-term storage in the air compared to the uncoated NCM811 sample. Our studies proposed an effective surface modification strategy to enhance the electrochemical performance of layered ternary oxides for high performance-cathodes in commercial LIBs. [Display omitted] Ni-rich layered 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. However, the relatively high reactivity of Ni in NCM811 cathodes results in severe capacity fading originating from the undesired side reactions that occur at the cathode-electrolyte interface during prolonged cycling. Therefore, the trade-off between high capacity and long cycle life can obstruct the commercialization process of Ni-rich cathodes in modern lithium-ion batteries (LIBs). In addition, high sensitivity toward air upon storage greatly limits the commercial application. Herein, a facile surface modification strategy is introduced to enhance the cycling and in-air storage stability of NCM811. The NCM811 with a uniform SrTiO 3 (STO) nano-coating layer exhibited outstanding electrochemical performances that could deliver a high discharge capacity of 173.5 mAh⋅g−1 after 200 cycles under 1C with a capacity retention of 90%. In contrast, the uncoated NCM811 only provided 65% capacity retention of 130.8 mAh⋅g−1 under the same conditions. Structural evolution analysis suggested that the STO coating acted as a buffer layer to suppress the dissolution of transition metal ions caused by the HF attack from the electrolyte and promote the lithium diffusion during the charge–discharge process. In addition, the constructed STO layer prevented the exposure of NCM811 to H 2 O and CO 2 and thus effectively improved the in-air storage stability. This work offers an effective way to enhance the performance stability of Ni-rich oxides for high-performance cathodes of lithium-ion batteries. [ABSTRACT FROM AUTHOR]

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]