Abstract: In recent years, it is interesting that cement based composites can be used for building energy storage. In this paper, a kind of optimized cement based composite electrolyte was prepared by mixing Portland cement and acrylamide (AM). The effects of AM mass fraction of 0%, 25.0%, 27.5%, 30.0%, 32.5% and 35.0% on the ionic conductivity, mechanical properties and microstructure of the structural electrolyte were investigated. The multifunctional analysis shows that the increase of AM content is helpful to improve the ionic conductivity of Portland cement based composite electrolyte, but it inevitably reduces the compressive strength of electrolyte. When AM content is 30.0%, the ionic conductivity and compressive strength the Portland cement based composite electrolyte reach an ideal balance. At this time, the compressive strength is as high as 41.1 MPa, and the ionic conductivity is up to 22.47 mS·cm^-1. In addition, integrated structural supercapacitors were assembled with these structural electrolytes sandwiched by rGO electrodes, and a series of electrochemical performance tests were carried out. It is found that the maximum area specific capacitance of the structure supercapacitor based on Portland cement based composite electrolyte with AM content of 30.0% can reach 96.8 mF·cm^-2. In addition, its area capacitance retention rate keeps 91.08% after 5 000 charge-discharge cycles at a current density of 0.1 mA·cm^-2, indicating that the structural supercapacitor has a broad prospect in the field of building energy storage application.

Key words: Portland cement electrolyte, acrylamide, structural supercapacitor, compressive strength, electrochemistry