High-energy-density cathode achieved via the activation of a three-electron reaction in sodium manganese vanadium phosphate for sodium-ion batteries

Chen, Y., Lia, Q., Wang, P., Liao, X., Chen, J., Zhang, X., Zheng, Q., Lina, D. and Lam, K. (2023) High-energy-density cathode achieved via the activation of a three-electron reaction in sodium manganese vanadium phosphate for sodium-ion batteries. Small, 19(50), 2304002. (doi: 10.1002/smll.202304002) (PMID:37621029)

Abstract

Sodium superionic conductor (NASICON)-type Na3V2(PO4)3 has attracted considerable interest owing to its stable three-dimensional framework and high operating voltage; however, it suffers from a low-energy density due to the poor intrinsic electronic conductivity and limited redox couples. Herein, the partial substitution of Mn3+ for V3+ in Na3V2(PO4)3 is proposed to activate V4+/V5+ redox couple for boosting energy density of the cathodes (Na3V2‒xMnx(PO4)3). With the introduction of Mn3+ into Na3V2(PO4)3, the band gap is significantly reduced by 1.406 eV and thus the electronic conductivity is greatly enhanced. The successive conversions of four stable oxidation states (V2+/V3+, V3+/V4+, and V4+/V5+) are also successfully achieved in the voltage window of 1.4–4.0 V, corresponding to three electrons involved in the reversible reaction. Consequently, the cathode with x = 0.5 exhibits a high reversible discharge capacity of 170.9 mAh g−1 at 0.5 C with an ultrahigh energy density of 577 Wh kg−1. Ex-situ x-ray diffraction (XRD) analysis reveals that the sodium-storage mechanism for Mn-doped Na3V2(PO4)3 consists of single-phase and bi-phase reactions. This work deepens the understanding of the activation of reversible three-electron reaction in NASICON-structured polyanionic phosphates and provides a feasible strategy to develop high-energy-density cathodes for sodium-ion batteries.

• Item Type: Articles
• Additional Information: This work was supported by Natural Science Foundation of Sichuan Province (2022NSFSC0222) and Sichuan Science and Technology Program (2023NSFSC0439).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Lam, Dr Koko
• Authors: Chen, Y., Lia, Q., Wang, P., Liao, X., Chen, J., Zhang, X., Zheng, Q., Lina, D., and Lam, K.
• College/School: College of Science and Engineering > School of Engineering > Systems Power and Energy
• Journal Name: Small
• Publisher: Wiley
• ISSN: 1613-6810
• ISSN (Online): 1613-6829
• Published Online: 24 August 2023
• Copyright Holders: Copyright © 2023 The Authors.
• First Published: First published in Small 19(50): 2304002
• Publisher Policy: Reproduced under a Creative Commons license