In situ gelation of aqueous sulfuric acid solution for fuel cells

Aqueous sulfuric acid solution is a versatile liquid electrolyte for electrochemical applications and gelation of it has the advantages of easy shaping and reduced leaking. Herein, aqueous sulfuric acid solutions with concentrations of 1–4 mol L−1 are fabricated into gel membranes by in situ polymerization of acrylamide as a monomer and divilynbenzene as a crosslinker for fuel cell applications. The gel membrane with an acid concentration of 3.5 mol L−1 exhibited the maximum proton conductivity of 184 mS cm−1 at 30 °C. Tensile fracture strength of the gel membrane reached 53 kPa with a tensile strain of 14. Thermogravimetric analysis reveals that the gel membranes are thermally stable at temperatures up to 231 °C. The gel membranes are successfully assembled into fuel cells and a peak power density of 74 mW cm−2 is achieved. The fuel cell maintains steady operation over 200 h. In situ gelation of aqueous sulfuric acid solution offers an efficient strategy to prepare gel electrolytes for electrochemical devices.