Bimetal‐Substituted Polyanion Cathode for Sodium‐Ion Batteries: Less Vanadium and Boosted Low‐Temperature Kinetics

Abstract

Sodium‐ion batteries (SIBs) have emerged as an attractive alternative for large‐scale energy storage due to their low cost and high safety. The selection of cathode materials, which determine SIB performance, becomes a crucial aspect. Vanadium‐based phosphates are known for their multielectron transfer properties and stable structure, but their intrinsic electronic conductivity is limited. In this regard, bimetallic substitution is an excellent modification method for improving the conductivity property. Herein, a novel Na4VMn0.7Ni0.3(PO4)3@C (NVMNP@C) cathode with less vanadium is designed for SIBs, which exhibits outstanding electrochemical performance at 25 °C, delivering rate capacity of 67 mA h g−1 at 3 A g−1, and long‐term cyclability of remaining 74.6% after 4800 cycles at 2 A g−1. Furthermore, excellent low‐temperature adaptability (82 mA h g−1 at 20 mA g−1, 60 mA h g−1 at 400 mA g−1, and 90.4% capacity retention after 230 cycles at 100 mA g−1) at −40 °C is also achieved. This unique work has broken a feasible pathway for high‐performance SIB cathode at low temperature.