<b>Kinetic Origin of Planar Gliding in Single-Crystalline Ni-Rich Cathodes</b>
Xin‐Hai Meng, Ting Lin, Huican Mao, Ji‐Lei Shi, Hang Sheng, Yu‐Gang Zou, Min Fan, Kecheng Jiang, Ruijuan Xiao, Dongdong Xiao, Lin Gu, Li‐Jun Wan, Yu‐Guo Guo
Abstract
Single-crystalline Ni-rich cathodes with high capacity have drawn much attention for mitigating cycling and safety crisis of their polycrystalline analogues. However, planar gliding and intragranular cracking tend to occur in single crystals with cycling, which undermine cathode integrity and therefore cause capacity degradation. Herein, we intensively investigate the origin and evolution of the gliding phenomenon in single-crystalline Ni-rich cathodes. Discrete or continuous gliding forms are revealed with new surface exposure including the gliding plane (003) and reconstructed (-108) under surface energy drive. It is also demonstrated that the gliding process is the in-plane migration of transition metal ions, and reducing oxygen vacancies will increase the migration energy barrier by which gliding and microcracking can be restrained. The designed cathode with less oxygen deficiency exhibits outstanding cycling performance with an 80.8% capacity retention after 1000 cycles in pouch cells. Our findings provide an insight into the relationship between defect control and chemomechanical properties of single-crystalline Ni-rich cathodes.