# Solution-combustion synthesis of Na3(VO1-x)2(PO4)2F1+2x as a positive electrode material for sodium-ion batteries

## TL;DR

A new self-combustion method creates a sodium-vanadium fluorophosphate material with high performance for sodium-ion batteries.

## Contribution

The study introduces a self-combustion synthesis for fluorinated polyanion compounds with excellent electrochemical performance.

## Key findings

- Phase-pure NVPF with 98 nm grain size was synthesized using a citrate-nitrate combustion process.
- The material showed high capacity (111 mAh g−1), cyclability (94% retention), and high-rate performance (91% retention).

## Abstract

Sodium-vanadium fluorophosphates (NVPF) comprise a family of highly potent positive electrode materials for sodium-ion batteries, combining high energy density due to their high operating potential and good high-rate performance provided by NASICON structure. In this study, a self-combustion approach to synthesise Na3(VO1-x)2(PO4)2F1+2x (0 ≤ x ≤ 1) is reported. The method described here is based on a citrate-nitrate combustion process. As a result of the synthesis, phase-pure NVPF with uniform morphology and average grain size of 98 nm is obtained. Moreover, the self-combustion method implemented in this study results in the acquisition of a powder with excellent performance in Na-ion systems, showing high capacity (ca. 111 mAh g−1), cyclability (ca. 94% of capacity retention), and high-rate performance (ca. 91% of capacity retention). The self-combustion technique described in this paper shows a promising approach to synthesising fluorinated polyanion compounds for Na-ion batteries.

Oskar Grabowski and colleagues describe a self-combustion synthesis of sodium-vanadium fluorophosphate. The obtained powder showed good electrochemical properties, making it a suitable material for positive electrodes for sodium-ion batteries.