A tri-electrode configuration for zinc-air batteries using gel polymer electrolytes

•Tri-electrode battery configurations using gel polymer electrolytes are studied.•Effects of crosslinking density on OER is evaluated.•Effects of ZnO on ORR and OER are revealed separately.•Cycling performance is shown in different orientations without leaking. To increase the cyclability of rechargeable zinc-air batteries (ZABs) using gel polymer electrolytes (GPEs), battery design and structure need to be optimized. Two different configurations for a tri-electrode battery have been developed in this work; i.e., a planar cell and a sandwich cell. Discharge-recharge cycling tests at 5 mA cm–2 show that the sandwich cell is more suitable for ZABs than the planar cell. Various additives for the GPEs, such as cross linking agents and ZnO, have also been evaluated using the tri-electrode design. Cross linking density affects the physical state of GPEs, which in turn affects the oxygen evolution reaction as there is an adverse effect of excessive GPE/Ni foam electrode contact area because oxygen bubbles may be trapped in the GPE. The addition of ZnO to the oxygen reduction reaction side of the battery enhances the cycling performance of ZABs; i.e., the battery can withstand at least 100 cycles at 5 mA cm–2 with an efficiency of 62% during the first cycle. [Display omitted]