Lithium-ion batteries are crucial for decarbonizing transportation and power grids, but their reliance on cobalt raises sustainability concerns. This paper reports on stoichiometry control in synthesizing Li-deficient composite-structured LiNi_0.95Mn_0.05O₂, which outperforms traditional layered counterparts. Li-deficiency suppresses phase transformation and crystal growth, leading to small composites with low anisotropic lattice expansion/contraction. The Li-deficient LiNi_0.95Mn_0.05O₂ shows 90% first-cycle Coulombic efficiency, 90% capacity retention, and minimal voltage fade over 100 deep cycles, suggesting its potential as a cobalt-free cathode.

Ke Chen, Pallab Barai, Ozgenur Kahvecioglu, Lijun Wu, Krzysztof Z. Pupek, Mingyuan Ge, Lu Ma, Steven N. Ehrlich, Hui Zhong, Yimei Zhu, Venkat Srinivasan, Jianming Bai, Feng Wang