Interlinking Primary Grains with Lithium Boron Oxide to Enhance the Stability of LiNi_0.8Co_0.15Al_0.05O₂

Destructive effects of surface lithium residues introduced in synthesis and degradation of the microstructure and electrode/electrolyte interface during cycling of Ni-rich cathode materials are the major problems hindering their wide application. Herein, we demonstrate an exquisite surface modification strategy that can utilize lithium residues on the surface of LiNi_0.8Co_0.15Al_0.05O₂ to form a uniform coating layer of lithium boron oxide on the surface of the material. The resulting lithium boron oxide layer can not only efficiently serve as a protective layer to alleviate the side reactions at the electrode/electrolyte interface but also tightly interlink the primary grains of the LiNi_0.8Co_0.15Al_0.05O₂ material to prevent the material from degradation of the microstructure. As a result, the optimized lithium boron oxide-coated LiNi_0.8Co_0.15Al_0.05O₂ material exhibits a high initial discharge capacity of 202.1 mAh g^–1 at 0.1 C with a great capacity retention of 93.59% after 100 cycles at 2 C. Thus, the uniform lithium boron oxide coating endows the NCA material with excellent structural stability and long-term cycling capability.