The effects of sodium fluoride as the electrolyte additive on the electrochemical performances of magnesium–8lithium–0.5zinc electrode in sodium chloride solution

Abstract

The electrochemical performance of Mg–8Li–0.5Zn electrode in 0.7 mol L−1 NaCl solution with different concentrations of NaF (0.0, 0.2, 0.5, 0.8, 1.0, 1.2 and 1.5 mmol L−1) was investigated by means of potentiodynamic polarization, potentiostatic current–time curves, electrochemical impedance spectroscopy, scanning electron microscopy and utilization efficiencies. The findings indicate that Mg–8Li–0.5Zn electrode in 0.7 mol L−1 NaCl solution with 1.0 mmol L−1 NaF has a higher discharge current density than that in 0.7 mol L−1 NaCl solution with the other concentrations of NaF that were investigated. The addition of 1.0 mmol L−1 NaF to the NaCl electrolyte solution loosens the product film and the oxidation products on the alloy surfaces of the electrode, which produces deeper and larger channels, as observed by the SEM investigation, compared with those in 0.7 mol L−1 NaCl solution without any NaF. The addition of 1.0 mmol L−1 NaF in 0.7 mol L−1 NaCl solution improves the continuous discharging utilization efficiency of Mg–8Li–0.5Zn electrode by more than 18.80%, and enhances the interval discharge utilization efficiency of Mg–8Li–0.5Zn electrode by more than 27.90%.