Entropic Design of Anionic Site to Improve Anionic Redox Stability in Lithium‐Rich Cathode

Abstract

Cobalt‐free manganese‐rich layered oxide is considered one of the most promising cathode materials for next‐generation lithium‐ion batteries due to its high capacity and low cost. However, irreversible anionic redox (OAR) leads to serious failure problems and hinders its wide application. To solve the above problems, the entropy design strategy of anionic sites is proposed, which is more direct and relevant to the regulation of the OAR process compared to the traditional entropy design of TM sites. The entropic design improves the structural diversity and long‐range disorder of the material, which effectively inhibits oxygen release and drastic structural strain, and alleviates structural degradation. After 400 cycles at 1C, the capacity and voltage decay per cycle are only 0.092 mAh g−1 and 1.36 mV, respectively. The long cycle test (10C and 1000 cycles) at high current shows that the voltage and capacity decay are only 0.04 mAh g−1 and 0.66 mV per cycle, respectively. Meanwhile, the rate performance at 10C reaches 175 mAh g−1. The charge compensation regulation and performance enhancement mechanism are investigated by systematic in‐situ/ex‐situ characterization and theoretical calculation. This research provides new ideas for the design of lithium‐rich cathodes with stable OAR and high structural adaptability.