Proton Superhighways Enabled by Hofmeister‐Electrostatic Synergy in All‐Inorganic Polyoxometalate Hydrogels for Electronics

Abstract Constructing polyoxometalate‐counterion systems capable of forming precise supramolecular nanostructures is critically important but highly challenging. Here ion‐specific effects are exploited to orchestrate multiscale phase transitions in isopolyoxometalate‐cation supramolecular assemblies, enabling on‐demand transformation from macrophase separation to nanostructured hydrogels. Gelation proceeds through ion‐pair‐driven charge inversion of the clusters, facilitating 1D supramolecular polymerization mediated by salting‐in anions through synergistic hydrogen bonding and electrostatic interactions. Crucially, these ion‐engineered hydrogels exhibit anomalous proton conduction over a wide temperature range, enabling temperature sensors with ultra‐wide operational range, high sensitivity, and great stability. Integration of these sensors enabled real‐time thermal hazard mitigation in a prototype battery safety system. This work pioneers salting‐in anions encapsulation in isopolyoxometalate‐counterion systems to achieve inorganic soft superstructures, uncovering a previously unrecognized general Hofmeister‐electrostatic assembly principle in cluster chemistry.