Soft-chemical synthesis and high-temperature electrochemical characteristics of VO2

VO2 powder was synthesized by a new soft-chemical method using formaldehyde as a reductant. The influences of pyrolysis temperature and time on the phase and morphology of grains were investigated by using thermal gravimeter/differential thermal analysis(TG/DTA), X-ray diffraction(XRD), Fourier transform infrared(FTIR) spectroscopy and scanning electron microscope(SEM). The positive electrode discharge performances of Li-B/LiCl-KCl/VO2 thermal battery at 500 °C were studied. The results show that the product is mainly non-crystal when the precursor of VO2 is heated below 300 °C. VO2(B) appears and transits into VO2(R) irreversibly as the heating temperature rises. The open-circle voltage of VO2 is 2.6 V (vs Li-B), and the initial discharge voltage of 100 mA/cm2 at 500 °C is 2.52 V. The specific capacities of 100 mA/cm2 and 200 mA/cm2 at cut-off voltage of 1.4 V are 449 A·s/g and 539 A·s/g, respectively.