Ionomers can be engineered to have elastic moduli of E > 50 MPa and in the presence of specific ions become even tougher due to enhanced interactions between the charged polymer chains and the ions. This has mostly been exploited for coatings and could be translated to tough hydrogels based on metal-ligand interactions. Moreover, ionomers have been used for semi-permeable membranes (e.g., in batteries) and tough hydrogels could be applied in a similar manner towards emerging aqueous-based battery technologies (e.g., aqueous redox flow batteries).