A NASICON-type Na3.67Cu0.17Fe0.5V1.33(PO4)3 cathode with multi-electron reaction for high-energy sodium-ion battery

Abstract

Natrium superionic conductor (NASICON) compounds with robust structure and high Na⁺ conductivity have become an attractive cathode for sodium-ion batteries (SIBs). However, the specific capacity of NASICON compounds is relatively low. Herein, a NASICON type Na_3.67Cu_0.17Fe_0.5V_1.33(PO₄)₃ (NCFVP) cathode with multi-electron redox reaction is designed. The well-designed NCFVP manifests an ultra-high capacity (160 mA h g⁻¹ at 0.1 C), high energy density (450 W h kg⁻¹), and impressive cyclability (1% capacity degradation for 200 cycles at 0.2 C). Galvanostatic intermittent titration technique and multi-scan rate cyclic voltammetry reveal the fast Na⁺ diffusion kinetics of NCFVP. In situ X-ray diffraction reveals the highly reversible Na⁺ insertion/extraction in NCFVP via a solid solution reaction. This work provides a new cathode choice with multi-electron reaction and robust stability for SIBs.