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Nano-sized calcium zincate powders used as active materials for a secondary Zn electrode were prepared by a chemical co-precipitation method. The properties were studied by thermal gravimetric analysis (TGA), micro-Raman spectroscopy and nitrogen adsorption-desorption experiments. The secondary Zn electrodes using chemical coprecipitation calcium zincate powders (CP-ZnCa) and ballmilled calcium zincate powders (BM-ZnCa), were examined and compared. The electrochemical performance of the secondary Zn electrodes was systematically investigated by cyclic voltammetry and galvanostatic charge/discharge measurements. It was demonstrated that the electrochemical properties of the secondary Zn-pasted electrode using CPZnCa powders were greatly improved, as compared with conventional secondary ZnO electrodes. The results indicated that secondary Ni-Zn batteries using CP-ZnCa powders exhibited a better charge/discharge property and a longer lifecycle performance, compared with those based on ball-milled ZnO + Ca(OH) 2 (BM-ZnCa) powders.

In this study, a simple and environment-friendly method of preparing activated graphite felt (GF) for a vanadium redox flow battery (VRFB) by depositing the vanadium precursor on the GF surface and calcining vanadium oxide was explored. The intermediate material, VO2, generated carbon oxidation during the calcination. In contrast to the normal etching method, this method was simple and without a pickling process. On the surface of the activated GF, multiple pores and increased roughness were noted after the calcination temperature and surface area of the activated GF reached 350 °C to 400 °C and 17.11 m2/g, respectively. Additionally, the polarization of the activated GF decreased with resistance to the charge transfer at 0.27 Ω. After a single-cell test at current density of 150 mA/cm2 was performed, the capacity utilization and the capacity retention after 50 cycles reached 70% and 84%, respectively. These results indicated the potential use of activated GF as an VRFB electrode.

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