Mitigating the Surface Reconstruction of Ni-Rich Cathode <i>via</i> P2-Type Mn-Rich Oxide Coating for Durable Lithium Ion Batteries
Xiangsi Liu, Jialiang Hao, Maojie Zhang, Bizhu Zheng, Danhui Zhao, Yong Cheng, Zhanning He, Mintao Su, Chenpeng Xie, Mingzeng Luo, Peizhao Shan, Mingming Tao, Ziteng Liang, Yuxuan Xiang, Yong Yang
Abstract
Ni-rich materials have received widespread attention as one of the mainstream cathodes in high-energy-density lithium-ion batteries for electric vehicles. However, Ni-rich cathodes suffer from severe surface reconstruction in a high delithiation state, constraining their rate capabilities and life span. Herein, a novel P2-type NaxNi0.33Mn0.67O2 (NNMO) is rationally selected as the surficial modification layer for LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode, which undergoes a spontaneous Na+–Li+ exchange reaction to form an O2-type LixNi0.33Mn0.67O2 (LNMO) layer revealed by combining X-ray diffraction and solid-state nuclear magnetic resonance techniques. Owing to the specific oxygen stacking sequence, O2-type LNMO significantly prevents the initial layered structure of NCM811 from transforming to the spinel or rock-salt phases during cycling, thus effectively maintaining the integral surficial structure and the Li+ diffusion channels of NCM811. Eventually, the NNMO@NCM811 electrode yields enhanced thermal stability, outstanding rate performance, and long cycling stability with 80% capacity retention after 294 cycles at 200 mA g–1, and its life span is further extended to 531 cycles while enhancing the mechanical stability of the bulk material.