Electrochemical investigations of a high-capacity Na2CrO4/C nanocomposite anode for sodium-ion batteries

Abstract

Majority of the anodes in sodium-ion batteries (SIBs) show low working voltage which prevents long cycling due to formation of plating. In this study, Na2CrO4/C has employed a relatively high working voltage (similar to 1 V) anode for SIBs. The nanocomposite of Na2CrO4 and highly conducting super P carbon is synthesized using the ball mill method for high-performance SIBs. X-ray diffraction (XRD) graphs show a decrease in the peak intensity and expansion of full-width half-maximum which results in reduced size of the nanocomposite. Scanning electron microscopy further confirms the reduction of size from micro to the nanometer range. The Na2CrO4/C nanocomposite shows a specific capacity of 228 mAh g(-1) at 0.1 C rate during the initial cycle and 166 mAh g(-1) during the 100th cycle. The Na2CrO4/C nanocomposite exhibits a specific capacity of 71 mAh g(-1) at an elevated rate of 2.0 C. The structure of Na2CrO4/C nanocomposite is elucidated using in situ XRD and the outcomes show the transformation of material from crystalline to amorphous phase during cycling. X-ray absorption spectroscopy is employed to follow the oxidation/reduction change of Cr in the Na2CrO4/C nanocomposite.