Structural Cement‐Based Supercapacitors with Multifunctional Robustness for Energy Storage

Abstract The rapid deployment of renewable energy demands cost‐effective and scalable energy storage solutions. While cement‐based supercapacitors offer transformative potential, their development is hindered by charge storage capacity, mechanical strength, and environmental stability. Herein, a breakthrough carbon cement supercapacitor (CCS) with exceptional electrochemical performance and excellent robustness is engineered. The porous carbon cement (CC) electrode, characterized by high strength, extremely low resistance, and high‐connectivity conductive hydrogel electrolyte, is prepared by thermomechanical consolidation at 90 °C. Through in situ polymerization around sodium dodecyl sulfate (SDS)‐mediated carbon black (CB) surfaces, a CB‐hydrogel network is built inside the multiscale pore structure of the carbon‐cement electrode. The CCS exhibits a leading areal capacitance (1708 mF cm ^{− 2} ), over 83% capacitance retention after 10 000 cycles, high strength (>8 MPa), 92.2% capacitance retention under extreme loading conditions, a wide operating temperature range from −20 to 80 °C with less than 9% capacitance fluctuation, and incombustibility. This new device exhibits potential to revolutionize energy‐storage systems.