The effect of sodium stannate as the electrolyte additive on the electrochemical performance of the Mg-8Li-1Y electrode in NaCl solution

The effect of different concentrations of sodium stannate (Na ₂SnO₃) as the electrolyte additive in 0.7 mol L ^-1 NaCl electrolyte solution on the electrochemical performance of the Mg-8Li-1Y alloy electrode prepared by the vacuum induction melting method have been investigated by means of potentiostatic current-time, potentiodynamic polarization, and electrochemical impedance spectroscopy measurements as well as scanning electron microscopy. The performances of the magnesium-hydrogen peroxide (Mg-H₂O₂) semi-fuel cells with the Mg-8Li-1Y alloy as the anode were also determined. From the study, it has been found that the corrosion potential of the Mg-8Li-1Y electrode is slightly shifted to the negative direction and the corrosion current density is markedly decreased when different concentrations of Na₂SnO₃ are added to a 0.7 mol L^-1 NaCl electrolyte solution. The electrochemical impedance spectroscopy measurements show that the polarization resistance of the Mg-8Li-1Y electrode reduces in the following order with different concentrations of Na₂SnO₃: 0.20 mmol L^-1 > 0.00 mmol L ^-1 > 0.05 mmol L^-1 > 0.10 mmol L^-1 > 0.30 mmol L^-1. The electrochemical performance, illustrated by potentiostatic current-time curves, of Mg-8Li-1Y electrode in 0.7 mol L ^-1 NaCl electrolyte solution containing 0.30 mmol L^-1 Na₂SnO₃ is better than that in 0.7 mol L^-1 NaCl electrolyte solution containing Na₂SnO₃ in other concentrations. The addition of Na₂SnO₃ to the NaCl electrolyte solution loosens the product film and changes the size and thickness of the micro-clumps of the oxidation products. The Mg-H₂O ₂ semi-fuel cell with the Mg-8Li-1Y anode in 0.7 mol L^-1 NaCl solution containing 0.30 mmol L^-1 Na₂SnO₃ presents a maximum power density of 112 mW cm^-2 at room temperature.