Development of cement-based supercapacitors enabled by graphitic carbon produced from methane pyrolysis

This study develops cement-based supercapacitors (CBSCs) using a sustainable graphitic carbon co-product (GC) derived from iron-ore-catalysed methane pyrolysis. Unlike conventional carbon additives, which are costly and carbon-intensive to produce, the GC used in this study offers an environmentally friendly alternative for manufacturing CBSCs. Physicochemical characterisation indicates that GC is a highly ordered carbon that is uniformly dispersed, facilitating the preparation of carbon-cement slurry. Cementitious electrodes modified with 5 wt% GC show improved conductivity as well as enhanced compressive and flexural strengths, reaching 2.85 mS/cm, 51.9 MPa, and 7.2 MPa, respectively. Electrochemical results reveal that the CBSCs prepared using two 40 × 40 × 10 mm 3 cement-based electrodes containing 5 wt% GC deliver superior performance, with a specific capacitance of 9.8 mF/g and a capacitance retention of 85.1 %. Impressively, the assembled CBSC can light up 10 LEDs simultaneously for 25 s. The findings expand the potential applications of concrete components with integrated energy-storage capability and contribute to the development of sustainable energy-storage systems in smart buildings and civil infrastructure. • Graphitic carbon from methane pyrolysis exhibits high thermal stability and low defect density. • Electrical conductivity of GCCEs increases with the increase in GC and the decrease in the thickness. • Fully cured GCCEs shows systematic changes, affecting formation of conductive pathways by GC particles. • GC-CBSC assembled using 10 mm GCCE-5 exhibits the best electrochemical properties.