A novel calcination method towards layered Ni-rich cathode with enhanced electrochemical performances and regulated oxygen vacancies

Abstract

Layered Ni-rich cathodes that simultaneously possess high-energy density with robust cyclic performances are highly desired to the application of high-power lithium-ion battery. However, the formation of Li+/Ni2+ cation mixing and oxygen vacancies is an inevitable occurrence that causes poor crystal structure, leading to detrimental effects on electrochemical performance during traditional high-temperature calcination. Herein, the LiNi0.9Co0.05Mn0.05O2 cathode material with enhanced electrochemical performances was prepared via a novel calcination method replacing LiOH of Li2O2 (NCM-O2), which could effectively solve the reduction of Ni3+ and the information of oxygen vacancies and Li+/Ni2+ cations mixing. The effect of Li2O2 on the preparation of LiNi0.9Co0.05Mn0.05O2 was systematically investigated. The novel calcination method increased the oxygen pressurization and changed the redox conversion equation, thus reducing Li+/Ni2+ cation mixing (3.33% to 2.12%) and regulating the formation of oxygen vacancies (9.44% to 6.39%). As a consequence, the NCM-O2 based battery exhibits remarkable cycling stability from room temperature (RT) to 50 °C in a voltage range of 2.8–4.3 V. As-assembled Li/NCM-O2 battery shows superior cyclability of 177.9 mAh g−1 after 100 cycles at 1C under RT with a cycle retention of 95.2%. As such, our work of novel calcination method opens a simple and effectively route to develop layered Ni-rich cathodes with enhanced electrochemical performances for high-power lithium-ions batteries.