Portland cement electrolyte for structural supercapacitor in building application

Inorganic cementitious materials based supercapacitors have been attracting interest due to their critical role in large scale civil engineering applications. Normally, inorganic cementitious materials act as structural phases, which are soaked in KOH aqueous solution to assemble into structural electrolytes. Nine 2 wt% alkali metal salts were mixed with Portland cement in advance rather than immersed in their aqueous solution to fabricate structural electrolytes for the first time in this work. The microstructure and multifunctional performances of Portland cement electrolytes were studied as a function of phase composition for various formulated high performance cement systems. The 2 wt% Na2SO4-Portland cement sample showed the best multifunctional properties with an ionic conductivity of 0.062 S cm−1 and a compressive strength of 32.67 MPa. The resulting Portland cement electrolytes were also assembled with rGO foam electrodes into structural supercapacitors, which exhibited a highest areal capacitance of 35.18 mF cm−2. The reported structural supercapacitors in the form of cement-matrix composites are important for large scale civil engineering application.