Semi‐Solid Superprotonic Supramolecular Polymer Electrolytes Based on Deep Eutectic Solvents and Polyoxometalates

Abstract Supramolecular polymers (SPs) exhibit intriguing benefits in functional soft materials due to their dynamic bonding feature. However, most SPs can only exist in the solution state and fail to form bulk materials, which limits their applications. Here, we report the fabrication of semi‐solid bulk SP materials by using polyoxometalate (POM) nanoclusters as supramolecular cross‐linkers to solidify a deep eutectic solvent (DES). The abundant protons and strong hydrogen bonds afforded by POMs enable these SP materials as superprotonic conductive electrolytes with sufficient mechanical strength, showing a proton conductivity more than 1×10 −4 S cm −1 and a breaking strength exceeding 1 MPa at room temperature. Moreover, the thermodynamic reversibility of the SP electrolytes allows them to form a stable electrode‐electrolyte interface by a facile melt‐infiltration strategy upon mild heating, which leads to improved performance in supercapacitors. This work presents an innovative DES/POM hybrid system as a promising platform to develop functional supramolecular materials for energy and electronic applications.