A geopolymer membrane for application in a structural mechanics and energy storage difunctional supercapacitor

A structural mechanics and energy storage difunctional supercapacitor based on a geopolymer membrane injected with a 0.5 M Na₂SO₄ electrolyte and a pseudocapacitive electrode Mn₇O₁₃ is designed and assembled. The geopolymer membrane is prepared as a structural electrolyte with metakaolin and alkaline activator solution. The wide channels in the geopolymer matrix provide paths for ion movement. The Mn₇O₁₃ electrode is prepared by different hydrothermal treatments at different temperatures and times, and assembled with activated carbon and a geopolymer with different moduli to form a difunctional supercapacitor. The results show that the electrode sample annealed at 300 °C for 45 min after hydrothermal treatment at 160 °C for 24 h exhibits the best comprehensive performance. The specific capacitance of the electrode is 175.5 F g^-1 (2392.6 F m^-2) at 1 A g^-1, and the specific capacitance of the difunctional structure supercapacitor assembled with a geopolymer with a modulus of 1.2 and cured for 28 days is 144.12 F g^-1 (1960.0F m^-2) at 1 A g^-1 under 15 MPa.