Lithium Deficiencies Engineering in Li-Rich Layered Oxide Li_1.098Mn_0.533Ni_0.113Co_0.138O₂ for High-Stability Cathode

Abstract

Li-rich layered oxides have been in focus because of their high specific capacity. However, they usually suffer from poor kinetics, severe voltage decay, and capacity fading. Herein, a long-neglected Li-deficient method is demonstrated to address these problems by simply reducing the lithium content. Appropriate lithium vacancies can improve dynamics features and induce <i>in situ</i> surface spinel coating and nickel doping in the bulk. Therefore, the elaborately designed Li_1.098Mn_0.533Ni_0.113Co_0.138O₂ cathode possesses improved initial Coulombic efficiency, excellent rate capability, largely suppressed voltage decay, and outstanding long-term cycling stability. Specifically, it shows a superior capacity retention of 93.1% after 500 cycles at 1 C (250 mA g^-1) with respect to the initial discharge capacity (193.9 mA h g^-1), and the average voltage still exceeds 3.1 V. In addition, the discharge capacity at 10 C can be as high as 132.9 mA h g^-1. More importantly, a Li-deficient cathode can also serve as a prototype for further performance enhancement, as there are plenty of vacancies.