Fig. 2

Cycling profile (30 min discharge and charge; 0.22% of the theoretical capacity based on the mass of Zn) of electrically rechargeable zinc oxygen batteries at 5.0 mA cm⁻² and Zn foil as anode with: (a) the spaces between housing, Sn current collector and zinc anode are carefully isolated with PTFE as depicted in Fig. 1; (b) the electrolyte can infiltrate the spaces in between because no isolation is used. The cell potential presents a significant change during discharge and charge when the electrolyte infiltrates the spaces in between the components, which allows side reactions to take place. Photographs of the Sn foil current collector taken from exemplary, comparable batteries: (c) pristine; (d) after cycling for 125 h at 2.0 mA cm⁻² with isolation between the spaces (e) after cycling for 70 h at 2.0 mA cm⁻² with electrolyte infiltration between spaces. Here, the RuSn73-GDE was used as cathode¹² for all batteries.