Electrochemical Study of NaFePO4 Cathode Material in Aqueous Sodium-ion Electrolyte

Abstract

Aqueous rechargeable sodium-ion batteries (ARSIBs) have received more attention because of their low cost, the vast abundance of sodium on the earth, and possible application for smart grid-scale energy storage systems. This work reports the synthesis of NaFePO4 by a low-temperature ionothermal method using deep eutectic solvent (DES). The physical characterization of the synthesized material is done using X-Ray Diffraction (XRD), Scanning electron microscopy (SEM), Energy Dispersive X-ray analysis (EDAX), thermogravimetry analysis (TGA), and differential scanning calorimetry (DSC) to evaluate its crystal size, structure, composition, and morphology. The electrochemical behavior of NaFePO4 in 5M NaNO3 is studied using cyclic voltammetry (CV) and galvanostatic charge-discharge techniques. The electrochemical study revealed that the synthesized cathode material, NaFePO4 exhibits excellent electrochemical performance at high current rates. The full cell NaTi2(PO4)3/5M NaNO3/NaFePO4 delivers a discharge capacity of 96.96 mAh g-1at C/5rate and is 62.96% of the theoretical capacity. The cell retains a discharge capacity of 76 mAh g-1 over 50 cycles with good rate capability.