Synthesis of NaFePO₄ Material Using the Electrochemical Sodiation Method as a Sodium-Ion Battery Cathode

Abstract

One key area of innovation for improving the performance of sodium-ion batteries (SIBs) lies in their cathode materials. A particularly promising cathode material for SIBs is NaFePO₄. Based on previous research, SIBs using NaFePO₄/graphite have demonstrated satisfactory battery performance. The synthesis of NaFePO₄ can be efficiently carried out using the electrochemical sodiation method. Therefore, this study will synthesize NaFePO₄ via the electrochemical sodiation process for use as an SIB cathode. The electrochemical sodiation method for producing NaFePO₄ involves immersing FePO₄/Al in a Na₂SO₄ solution. Results obtained from FTIR analysis show a shift in the wavenumber peaks of Fe and PO₄ in the FePO₄ material relative to NaFePO₄, specifically from 560 cm⁻¹to 555 cm⁻¹(Fe) and from 1000 cm⁻¹to 997 cm⁻¹(PO₄). SEM test results indicate that the particle sizes of the FePO₄ and NaFePO₄ materials are 0.4–0.6 microns and 0.5 microns, respectively. EDX test results also confirm the presence of Na ions in the NaFePO₄ material (12.26% by mass). These results demonstrate that the incorporation of Na ions into the FePO₄/Al material via the electrochemical sodiation method was successfully achieved. The SIB was fabricated using a NaFePO₄/graphite electrode from the previous synthesis. Performance test results of the SIB with the NaFePO₄/graphite electrode showed a capacity of 9.23 mAh/g at 0.1 C and a coulombic efficiency of 17.86%.