Gel polymer electrolyte compositions including a cross-linked three-dimensional polymer network and an electrolyte composition comprising an electrolyte and water are disclosed. The gel polymer electrolyte compositions can be included in an aqueous electrochemical cell, in which a gel polymer electrolyte can be positioned between an anode and a cathode. Methods of forming a gel polymer electrolyte in the form of a film, and methods of forming an aqueous electrochemical cell including a gel polymer electrolyte, are also disclosed.