High‐Entropy Layered Oxide Cathodes for Sodium‐Ion Batteries

Abstract

Material innovation on high-performance Na-ion cathodes and the corresponding understanding of structural chemistry still remain a challenge. Herein, we report a new concept of high-entropy strategy to design layered oxide cathodes for Na-ion batteries. An example of layered O3-type NaNi_0.12 Cu_0.12 Mg_0.12 Fe_0.15 Co_0.15 Mn_0.1 Ti_0.1 Sn_0.1 Sb_0.04 O₂ has been demonstrated, which exhibits the longer cycling stability (ca. 83 % of capacity retention after 500 cycles) and the outstanding rate capability (ca. 80 % of capacity retention at the rate of 5.0 C). A highly reversible phase-transition behavior between O3 and P3 structures occurs during the charge-discharge process, and importantly, this behavior is delayed with more than 60 % of the total capacity being stored in O3-type region. Possible mechanism can be attributed to the multiple transition-metal components in this high-entropy material which can accommodate the changes of local interactions during Na⁺ (de)intercalation. This strategy opens new insights into the development of advanced cathode materials.