Lithium bis(trifluoromethane)sulfonimide (LiTFSI)-based polymer membranes have been proven to provide good mass transport of Li-ions due to their favoured diffusion by the weakly coordinating sulphonamide anion. However, a homopolymer prepared solely from LiTFSI-based monomer would result in an unsuitable membrane for electrodialysis due to the high water uptake, and even solubility in water, which would be detrimental to the mechanical strength. For this reason, the copolymeric membranes designed here are based on three main components; a LiTFSI-based monomer to provide Li-ion transport properties to the membrane, an alkyl methyacrylate comonomer to achieve a balance between water uptake and mechanical properties, and a crosslinking agent to further impart mechanical stability and tune the water uptake.