Trade‐offs between ion‐conducting and mechanical properties: The case of polyacrylate electrolytes

Abstract Polymer electrolytes (PEs) have been long recognized as the key materials to enable energy‐dense batteries and render flexible energy devices practically viable, owing to their chemical and mechanical reliability. However, much of their promise is yet to be realized. The room‐temperature ion conductivity of existing PEs still falls short of the implementation criterion of 10⁻⁴ S cm⁻¹ on the promise of acceptable mechanical properties, thereby precluding their practical application. The twin but inversely related duties of polymers, that is, functioning as both an ion‐conducting medium and a structural backbone, underlie this issue but are less elucidated systematically. The polyacrylate (PA) family is among promising polymer matrices on account of ester polarity, electrode compatibility, chemical tunability, and mechanical durability. The extensive applicability of PA in plasticized gels, dry solids, and emerging composites makes PA‐based PEs representative to illustrate the trade‐off between ion conduction and mechanical strength. We herein seek to outline the stated long‐standing conflict exemplified by PA‐based PEs, focusing on crucial strategies toward balancing and reconciling the two mutually exclusive properties, with the intention of offering designing guidelines for next‐generation PEs.