Ultrahigh‐Ni Cathode with Superior Structure Stability Enabled by a Covalent Bonding Strategy

Abstract

Ultrahigh‐nickel layered oxide cathodes are the most promising cathode materials for high‐energy lithium‐ion batteries. However, the rapid structural degradation during cycling charge‐discharge process limits its commercial application. Herein, we report a covalent pinning strategy to enhance structure stability of ultrahigh‐Ni cathode LiNi0.9Co0.06Mn0.04O2 (NCM90). Zr is gradient diffused into the lattice of NCM90 and forms Zr‐O bonds during the sintering process, which can effectively alleviate the lattice distortion like introducing pinning centers due to the stronger bond energy, enhancing its structure stability during charge‐discharge process. In the meanwhile, the Zr‐O on the surface of NCM90 powder forms LixZryOz coating layer due to the reaction with lithium residue, which prevents from the edge reconstruction and mitigates the occurrence of side reactions, as well as ensuring a fast Li+ diffusion pathway crossing the interface. As a result, the Zr‐O modified NCM90 (Zr‐NCM) achieves 88.8% remarkable capacity retention at 1 C after 200 cycles over 2.8‐4.3V, which is superior to the pristine NCM90 with 71.2% retention. This work demonstrates that the Zr‐O bonding can provide an effective structure pinning for the ultrahigh‐Ni cathode, which will largely guide the development of high‐performance lithium‐ion battery cathode materials.