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 TMO2, TM = transition metal ion(s)), as an analogue of lithium layered oxide cathodes (such as LiCoO2, LiNi x Co y Mn1–x–y O2), 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 NaO2 slabs, some undesired phase transitions are observed in Na x TMO2. Herein, we report a high-entropy configuration strategy for Na x TMO2 cathode materials, in which multicomponent TMO2 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 TMO2 slabs enhance the TM–O bonding energy to restrain oxygen release and thermal runaway, benefiting for the improvement of thermal safety.