Realizing Superior Cycle Stability of a Ni-Rich Layered LiNi_0.83Co_0.12Mn_0.05O₂ Cathode with a B₂O₃ Surface Modification

Ni-rich cathode is considered a promising cathode for its high specific capacity. However, a sharp capacity attenuation induced by interface problems limits the application of the cathode material. Herein, we propose a practical surface modification strategy by introducing diboron trioxide (B₂O₃) to the surface of LiNi_0.83Co_0.12Mn_0.05O₂ (NCM) cathode materials. B₂O₃-modified NCM shows superior cyclic stability with a capacity retention of 87.7 % at 1 C after 200 cycles in comparison to 69.4 % for a bare NCM. On the basis of material and electrochemical characterizations, we conclude that the superior cycle stability of B₂O₃-modified NCM material benefits from the formation of B₂O₃ coating and B³⁺ doping on the surface. The B₂O₃ coating layer that is confirmed by scanning and transmission electron microscopy can suppress surface side reactions and reduce the content of Li₂CO₃ on the surface. The B³⁺-doping surface is verified by X-ray diffraction and X-ray photoelectron spectroscopy and triggers a reduction of a small amount of Ni³⁺ to Ni²⁺. Furthermore, the combination of surface B₂O₃ coating and B³⁺ doping inhibits the irreversible phase transitions and extension of microcracks in the NCM material. The above surface modification strategy provides a direction for the acquisition of long-life cathode materials.