Effects of calcination temperature on electrochemical properties of cathode material Na4MnV(PO4)(3)/C synthesized by sol-gel method for sodium-ion batteries

摘要

The effects of calcination temperature on the physical and electrochemical performance of the Na4MnV(PO4)(3)/C composites, which are prepared by a sol-gel method combined with the subsequent calcination in inert atmosphere, are reported in this work. The Na4MnV(PO4)(3)/C composites are investigated by x-ray diffraction (XRD), N-2 adsorption/desorption isothermal, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and electrochemical measurements. The specific surface area, disorder of carbon, diffusion coefficients of Na+ (D-Na) and electrochemical performance of Na4MnV(PO4)(3)/C composites are greatly influenced by the calcination temperature. The surface area and disorder of carbon of Na4MnV(PO4)(3)/C substantially decrease with the calcination temperature increasing. While the D-Na and electrochemical performance of Na4MnV(PO4)(3)/C composites improve with the calcination temperature from 650 to 750 degrees C and then degrade with the calcination temperatures from 750 to 850 degrees C. The results reveal that the optimal calcination temperature for the Na4MnV(PO4)(3)/C composites is 750 degrees C and the corresponding Na4MnV(PO4)(3)/C composite possesses the highest capacity and the best rate capability and cyclability amongst all these Na4MnV(PO4)(3)/C composites in this work. (C) 2020 Elsevier B.V. All rights reserved.