Three Electron Reversible Redox Reaction in Sodium Vanadium Chromium Phosphate as a High‐Energy‐Density Cathode for Sodium‐Ion Batteries

By Yongjie Zhao, Xiangwen Gao, Hongcai Gao, Haibo Jin, John B. Goodenough. Advanced Functional Materials, 2020

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A sodium‐ion battery operating at room temperature is of great interest for large‐scale stationary energy storage because of its intrinsic cost advantage. However, the development of a high capacity cathode with high energy density remains a great challenge. In this work, sodium super ionic conductor‐structured Na3V2−xCrx(PO4)3 is achieved through the sol–gel method; Na3V1.5Cr0.5(PO4)3 is demonstrated to have a capacity of 150 mAh g−1 with reversible three‐electron redox reactions after insertion of a Na+, consistent with the redox couples of V2+/3+, V3+/4+, and V4+/5+. Moreover, a symmetric sodium‐ion full cell utilizing Na3V1.5Cr0.5(PO4)3 as both the cathode and anode exhibits an excellent rate capability and cyclability with a capacity of 70 mAh g−1 at 1 A g−1. Ex situ X‐ray diffraction analysis and in situ impedance measurements are performed to reveal the sodium storage mechanism and the structural evolution during cycling.

Subfields: Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/3994c41c3237aab4e543513f87487b2cfecd7e7e