H ⁺ ‐conducting‐ion‐based alginate polymer electrolytes for symmetric supercapacitors

Abstract Proton‐conducting alginate‐based polymer electrolytes were prepared using ammonium salt dopants and evaluated for symmetric supercapacitor applications. The optimized system exhibited ionic conductivity of ca . 10 −4 S cm −1 at ambient temperature, confirming efficient H + transport through the alginate network. Dielectric analysis indicated a thermally activated hopping mechanism, while electrochemical studies demonstrated a wide potential stability window up to 1.72 V. Cyclic voltammetry revealed nearly ideal double‐layer capacitive behaviour, with galvanostatic charge–discharge showing a specific capacitance of 12.48 F g −1 , low internal resistance and excellent coulombic efficiency. Long‐term cycling over 10 000 cycles confirmed outstanding stability with minimal performance loss. These results establish alginate‐based proton electrolytes as sustainable and high‐performance candidates for next‐generation energy storage, combining bio‐derived materials with durable electrochemical properties to meet the growing demand for safe, efficient and environmentally friendly supercapacitors. © 2026 Society of Chemical Industry.