Indium chloride as an electrolyte additive for primary aqueous Mg batteries

Highlights: • Cell voltage and specific energy of aqueous Mg-air battery were enhanced by the addition of 10 mM InCl₃ into 3.5 wt.% nacl solution. • Self-corrosion reaction of Mg-0.15Ca under anodic polarization was suppressed in 1 mM Incl₃-containing electrolyte. • Hydrolysis reactions of In³⁺ hindered electrolyte alkalization under anodic polarization leading to better discharge activity. • InCl₃ addition promoted more uniform dissolution and less chunk effect of Mg-0.15Ca anode. -- Abstract: Indium chloride (InCl₃) as an electrolyte additive for primary aqueous Mg batteries is evaluated in this work in terms of its effect on discharge potential, self-corrosion rate and utilization efficiency of a newly developed Mg-0.15Ca anode. InCl₃ addition to aqueous electrolyte leads to a more negative discharge potential but the enhancement weakens along with the consumption of In³⁺ to form In(OH)₃ precipitates during the discharge process. Utilization efficiency of the anode is increased by adding InCl₃ due to uniform anodic dissolution and suppressed self-corrosion with reduced chunk effect. Mg-air battery test results indicate that 10 mM InCl₃ as electrolyte additive significantly enhances the cell voltage of aqueous Mg-air battery to 1.74 V and the specific energy based on anode weight loss to 2.26 kWh/ kg at 1 mA cm⁻².