Influence of temperature on performance of CuV2O6 cathode for high voltage thermal battery

Abstract

The influence of heat treatment on the material properties and electrochemical properties of CuV2O6, as a candidate cathode for thermal batteries, was evaluated, where the discharge capacity and open-circuit voltage were measured. The properties of CuV2O6 calcined at different temperatures were determined using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA) and transmission electron microscopy (TEM) and energy dispersive spectroscopy. CuV2O6 was synthesized from NH4VO3 and CuCl2 via the hydrothermal method, and the XRD pattern was consistent with PDF#01-074-2117. The synthesized CuV2O6 was calcined at different temperatures, and the influence of calcination on the structures was analyzed by SEM and TEM. The SEM and TEM images showed that CuV2O6 was formed as rod-shaped crystals that gradually grew with increasing calcination temperature. However, upon calcination at 600 °C, the morphology of CuV2O6 was not maintained and the compound decomposed irregularly. XPS analysis showed that CuV2O6 is changed to Cu2V2O7 at higher calcination temperatures. Less than 5% weight change was observed in the TGA curves, including an increase in the weight at a higher temperature. The capacity of the CuV2O6 samples was approximately 300‒350 mAh/g as determined from the discharge curve, and CuV2O6 calcined at 550 °C had a higher activation energy than the other samples. Calcination at higher temperature could afford enhanced battery capacity. The data indicate that CuV2O6 may be a viable candidate material for thermal battery cathodes.