Electrode behaviors of Na-Zn liquid metal battery

Abstract

The electroreduction processes on a Mo electrode in a Na-Zn liquid metal battery cell with a molten NaCl-CaCl2-ZnCl2 electrolyte were investigated at 565°C. The effect of the battery operating parameters on the loss rate of Na was determined by using electrochemical techniques. The results indicated that the chemical reaction of the reduced Ca and Na with ZnCl2 takes place very quickly, and the electroreduction of Zn (II) to Zn is controlled by mass-transfer. The diffusion coefficient of Zn (II) ions was found to be approximately 3 × 10−6 cm2/s. Moreover, the results revealed that most of the reduced Na stick to the Mo electrode during charging. The increase of cell temperature and open-circuit time led to increase in the loss of Na. Volatilization is mainly responsible for the loss of Na, and a high current density during charging led to the severe competitive deposition of Zn with Na.