Electrochemical performance evolution of carbon-cement supercapacitors under the synergistic regulation of conductive networks and pore structures

Against the backdrop of continuous advancements in sustainable energy technologies, efficient energy storage has emerged as a critical research focus. A significant development trend is the integration of energy-storage functionality into structural materials, enabling the creation of multifunctional building components that simultaneously provide moderate load-bearing capacity and energy storage capability. In this study, carbon-cement supercapacitors were fabricated by tailoring the carbon black (CB) content and water-to-cement ratio (W/C) to regulate their three-dimensional microstructures. The corresponding effects of conductive network formation and pore structure evolution on electrochemical performance were systematically evaluated. The results indicate that increasing the CB content promotes the formation of a continuous and highly interconnected conductive network within the cement matrix, thereby enhancing electronic transport efficiency. Meanwhile, increasing the W/C elevates the material's porosity and facilitates ion migration and diffusion within the electrolyte. However, in systems with low CB content, an excessively high W/C disrupts the continuity of the conductive network, resulting in a reduction in capacitance. Under the optimized composition (W/C = 1.4, CB = 16%), the composite achieves excellent electrochemical performance, including a bulk conductivity of 37.34 mS/cm, an areal capacitance of 162.06 mF/cm² at 1 mA/cm², and energy and power densities of 17.53 μWh/cm² and 0.44 mW/cm², respectively. These findings highlight the synergistic roles of conductive network formation and pore-structure development in governing charge-storage behaviors, providing a solid mechanistic basis for the rational design and optimization of next-generation cement-based structural materials with integrated electrochemical energy-storage functionality.