Multifunctional structural supercapacitor based on graphene and magnesium phosphate cement

A novel structural supercapacitor is assembled with graphene electrodes and the magnesium phosphate cement separator. Magnesium phosphate cement acts as separator material for the first time due to its high strength and relatively high porosity. Magnesium phosphate cement is synthesized by acid-based reaction between phosphate and magnesia. Effects of processing parameters of magnesium phosphate cement, including M/P ratio and the curing time, on the electrochemical and mechanical properties are investigated. The maximum specific capacitance is as high as 46.38 F g(-1) with M/P ratio of 3 at the curing time of 1 day. Moreover, the structural supercapacitor exhibits a specific capacitance of 40.92 F g(-1) and simultaneously a compressive strength of 24.59 MPa with the M/P ratio of 3 at the curing time of 28 days. Thus, the optimal M/P ratio is 3 regarding the multifunctionality of structural supercapacitor.