Improving Rate Performance by Inhibiting Jahn–Teller Effect in Mn‐Based Phosphate Cathode for Na‐Ion Batteries

Abstract

AbstractManganese‐based phosphate cathodes are promising candidates for developing advanced sodium‐ion batteries, primarily driven by their reliable elemental abundance, low toxicity, and desirable cycling performance. However, the cooperative Jahn–Teller effect of Mn3+ will inevitably lead to structural disorder and irreversible phase transition, thus greatly harming the reversible capacity, rate, and cycling performance. Herein, a stable NASICON‐type Na3MnHf(PO4)3 cathode is demonstrated with a volume variation of 1.9% upon the process of Na+ extraction/insertion based on the robust Hf─O bond and symmetrical MnO6 octahedron. Moreover, making full use of the stepwise redox reactions of Mn2+/Mn3+/Mn4+, this cathode reveals excellent cycling stability with a capacity retention of 85.4% after 2500 cycles at 10 C. Matching with commercial hard carbon anodes, the assembled full cell keeps a capacity retention of 92.1% with the Coulombic efficiency close to 100% after 600 cycles at 1 C. The research promises opportunities for the structural amelioration of manganese‐based phosphate cathodes toward the application in high‐performance sodium‐ion batteries.