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

Na-ion layered oxide cathodes (Na x TMO 2 , TM = transition metal ion(s)), as an analogue of lithium layered oxide cathodes (such as LiCoO 2 , LiNi x Co y Mn 1- x - y O 2 ), 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 2 slabs, some undesired phase transitions are observed in Na x TMO 2 . Herein, we report a high-entropy configuration strategy for Na x TMO 2 cathode materials, in which multicomponent TMO 2 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 2 slabs enhance the TM-O bonding energy to restrain oxygen release and thermal runaway, benefiting for the improvement of thermal safety.