Application of isomorphic anion incorporation to enhance electrochemical performance of vanadium-based NASICON cathode materials

Abstract

Polyanionic fluorophosphate NaVPO₄F is an ideal cathode material for high power sodium-ion batteries due to its high theoretical specific capacity and operating voltage. However, its practical application has been hindered by low electronic conductivity and limited ionic mobility. To address this issue, this study successfully prepared the SiO₄⁴⁻ incorporated NaV(PO₄)_1−x(SiO)_xF cathode material. Research findings indicate that the incorporation of SiO₄⁴⁻ not only markedly reduces the material's diffusion activation energy but also enhances the kinetics of Na⁺ transport. Consequently, the modified NaV(PO₄)_0.9(SiO₄)_0.1F cathode material exhibits a several orders of magnitude improvement in the Na⁺ diffusion rate, leading to superior rate performance (achieving a specific capacity of 89.3 mA h g⁻¹ at 30 C) and exceptional cycling stability (retaining capacity retention of 75.8% after 2000 cycles at 10 C). Furthermore, when integrated into a full battery with hard carbon, the battery exhibits exceptional reliability and stability for high-performance applications.