Surface Miscible Structure Modulation of Li-Rich Cathodes by Dual Gas Surface Treatment for Super High-Temperature Electrochemical Performance

Li-rich manganese base oxides (LRNCM) are regarded as one of the most promising cathode materials among next-generation high-energy density Li-ion batteries due to the coupling effect of anion and cation redox. However, serious oxygen release, surface structure corrosion, and transformation seriously damage their electrochemical performance and restrict their commercialization process. Herein, a dual gaseous surface treatment strategy with ammonium bicarbonate is designed to reconstruct the surface chemical and structural characteristics of LRNCM. As a result, an enriched oxygen vacancies mixed-phase surface layer is achieved, which contains spinel phase and cation-disordered phase. The integration of the surface mixed phase effectively inhibits irreversible oxygen loss, prevents electrode corrosion, and promotes fast Li-ion diffusion. Accordingly, the modified cathode exhibits excellent specific capacity, high-rate capability, and superior cycle life at both 25 and 60 °C. Particularly at high temperatures, it achieves impressive performance: initial coulombic efficiency (82.0 vs 74.4%), cycling stability at 1 C after 100 cycles (92.6 vs 83.8%), and rate performance at 5 C (56.0 vs 48.7%). This reconfiguration approach introduces a novel idea for the design of cathode material interfaces. © 2023 Wiley-VCH GmbH.