Optimization of pulse current on energy storage of zinc-air flow batteries

Abstract

The energy storage of a zinc-air flow battery subject to a pulse current is experimentally addressed. The energy storage occurs in the form of zinc reduction during the charging process. The controlling parameters, affecting the zinc reduction, are an electrolyte temperature, a pulse current, a pulse frequency, and a duty cycle. A pulse current provides more controlling parameters compared to a uniform DC current. The Taguchi method is used to optimize the control parameters and maximize zinc reduction and energy storage efficiency. Five levels for four control parameters are adopted in the Taguchi method, and an L25 orthogonal table is introduced for experimental tests. The optimum set of control parameters is obtained as temperature 40 °C, current 1.4 A, pulse frequency 50 Hz, and duty cycle 85%. In this case, 3.668g zinc is produced during 1 h of charging process. By using the pulse current, the weight of produced zinc particles is increased up to 1.394g by compared to the regular DC current. Therefore, using pulse current parameters does contribute to the improvement of energy storage efficiency. Finally, the SEM study of the produced zinc particles demonstrates that employing a pulse current provides finer zinc particles compared to a DC current.