Lattice engineering to alleviate microcrack of LiNi0.9Co0.05Mn0.05O2 cathode for optimization their Li+ storage functionalities

Abstract

Intrinsic structural degradation and unstable surface chemical properties are bottlenecks of the Ni-rich cathode material for commercial application, which mainly originates from the lattice distortion and residual lithium. In this work, an effective molybdenum lattice engineering method to simultaneously enhance the intrinsic structural stability and the surface chemical properties of LiNi0.9Co0.05Mn0.05O2 cathode material is developed. The molybdenum on transition-metal sites visibly alleviates lattice distortion initiating microcracks by anchoring in the crystal lattice, meanwhile, the interface chemical stability is also significantly improved by consuming residual lithium to form the lithium molybdate oxide fast ion conductor coating layer. Therefore, the molybdenum-modified LiNi0.9Co0.05Mn0.05O2 delivers a remarkable Li+ storage functionalities (202.8 mAh g−1 with 90% capacity retention after 100 cycles), much higher than the pristine LiNi0.9Co0.05Mn0.05O2 (78% capacity retention after 100 cycles). In addition, the Density-Functional Theory (DFT) calculations announce that the Li+ migration the energy barrier of molybdenum-modified LiNi0.9Co0.05Mn0.05O2 is decreased, thus showing an ultrahigh discharge capacity of 166.4 mAh g−1 even at 8C rate. This strategy is very promising to provide a new insight into lattice engineering of cations doping effect, highlight the importance of lattice engineering in optimizing their energy functionalities.