Towards zinc-oxygen batteries with enhanced cycling stability: The benefit of anion-exchange ionomer for zinc sponge anodes

Electrically rechargeable zinc-oxygen batteries are promising for sustainable and resource-uncritical energy storage with high energy density. Their commercialization is hindered by the limited cycling stability-especially due to the zinc anode. In this study, we present a zinc anode that stands out with two advantages: The use of an energy-saving and low temperature preparation method, and the mechanical stabilization of the pore system with a lightweight anion-exchange ionomer. Our approach increases cycling stability for both the zinc-nickel oxide hydroxide cell and the zinc-oxygen cell: Electrochemical analysis in combination with operando X-ray diffraction measurements prove that the novel zinc anode is electrically rechargeable and can be cycled up to five times more often than zinc sponge anodes without anion-exchange ionomer to a depth of discharge of 35%. Scanning electron microscopy is used to evidence that the anion-exchange ionomer stabilises the entire pore system during cycling. We furthermore analyse zinc-oxygen batteries with anion-exchange ionomer at all parts-inside the zinc sponge anode, as separator and at the cathode. These cells can be electrically recharged with unprecedented high utilization of active material, and thus highlight the benefit of introducing an ion-selective coating into alkaline batteries with zinc anode.