Using High-Entropy Configuration Strategy to Design Na-Ion Layered Oxide Cathodes with Superior Electrochemical Performance and Thermal Stability.

Na-ion layered oxide cathodes (NaTMO, TM = transition metal ion(s)), as an analogue of lithium layered oxide cathodes (such as LiCoO, LiNiCoMnO), have received growing attention with the development of Na-ion batteries. However, due to the larger Na radius and stronger Na-Na electrostatic repulsion in NaO slabs, some undesired phase transitions are observed in NaTMO. Herein, we report a high-entropy configuration strategy for NaTMO cathode materials, in which multicomponent TMO slabs with enlarged interlayer spacing help strengthen the whole skeleton structure of layered oxides through mitigating Jahn-Teller distortion, Na/vacancy ordering, and lattice parameter changes. The strengthened skeleton structure with a modulated particle morphology dramatically improves the Na transport kinetics and suppresses intragranular fatigue cracks and TM dissolution, thus leading to highly improved performances. Furthermore, the elaborate high-entropy TMO slabs enhance the TM-O bonding energy to restrain oxygen release and thermal runaway, benefiting for the improvement of thermal safety.