Construction of structural supercapacitor with high energy density and mechanical strength based on dual-carbon electrodes and polyacrylamide-Portland cement-Na2SO4 electrolyte

Structured supercapacitors (SSCs) based on building materials have been recognized as potential devices for large-scale energy storage applications due to the huge volume and porosity. However, the decoupling of electrochemical properties and load-bearing capacity of building material-based electrolytes hinders the development of SSCs and the lack of compatible electrodes to match the electrolytes. In this work, SSCs with high energy density are successfully fabricated by designing a polyacrylamide (PAM)-Portland cement-Na2SO4 electrolyte with high compressive strength/ionic conductivity and assembling asymmetric dual carbon electrodes with the electrolyte. For the electrolyte, the PAM interacts with Portland cement to both maintain the compressive strength of SSCs (41.3 MPa) and offer a channel for the transport of charged ions generated from Na2SO4 which provides high ionic conductivity (40.9 mS cm−1). For the electrodes, the large-surface-area dual-carbon electrodes with different kinds of functional groups are rich in active sites for energy storage and have good contact with the electrolyte. Assembled with the electrodes and the electrolyte, SSCs exhibit the maximum energy density of 2.1 W h kg−1 at the power density of 1.62 W kg−1. This construction of the SSCs shows promise in simultaneously meeting the demands of structural function and energy storage. •A novel PAM-cement-Na2SO4 electrolyte is proposed.•PAM interacts with cement to promote the compressive strength.•PAM interacts with Na2SO4 to enhance the ionic conductivity.•Desirable dual-carbon electrodes are fabricated for collocation with the electrolyte.•The structural supercapacitors obtain high energy density and capacity retention.