Tailoring heterosized‐ion coupled electrolytes for enhanced pore compatibility in wide‐temperature supercapacitors

Abstract The strategic selection of electrolytes critically governs charge storage behavior in supercapacitors, with ionic liquid mixtures demonstrating particular promise for achieving high energy densities. This study pioneers a heterosized ion synergy approach, where rationally paired large/small anions dynamically adapt to hierarchical carbon pore architectures in the micropores region, compressing free volume through dense ion packing. This confinement effect critically restricts ionic degrees of freedom, enhancing adsorption stability at electrode interfaces. The heterosized ion‐pore structure matching system achieves significantly enhanced energy density, remarkably suppressed self‐discharge kinetics, and maintains robust capacitance retention across a wide temperature range (−20 to 80°C), establishing a new electrolyte design principle for high‐stability energy storage under thermal extremes.