Multifunctional cementitious composite supercapacitors: Advances in materials, electrochemical design, and structural energy storage

The growing demand for carbon-neutral infrastructure has accelerated the development of multifunctional construction materials capable of simultaneously providing structural support and electrical energy storage. Cementitious structural supercapacitors have emerged as a promising technology by integrating electrochemical energy storage directly into cement-based materials, thereby eliminating the need for separate structural and energy-storage systems. This review presents a comprehensive assessment of recent advances in cementitious structural supercapacitors, with particular emphasis on material selection, fabrication strategies, electrochemical mechanisms, and performance optimization. The roles of cementitious electrolytes, conductive fillers, carbon-based and transition metal oxide electrodes, separators, and current collectors are critically discussed, together with their influence on ionic conductance, capacitance, energy density, mechanical strength, and longterm durability. The effects of pore structure, polymer modification, interfacial engineering, and electrode architecture on electrochemical behavior are systematically analyzed to highlight the intrinsic trade-offs between structural integrity and energy-storage performance. Furthermore, recent progress in scalable manufacturing, multifunctional structural components, and practical applications, including building-integrated energy storage, smart infrastructure, and renewable energy systems, is reviewed.Existing challenges related to low energy density, interface stability, environmental durability, and large-scale implementation are also identified. Finally, future research directions focusing on sustainable materials, advanced electrode designs, low-carbon cementitious matrices, intelligent manufacturing, and real-world deployment are proposed. This review provides a comprehensive roadmap for the development of next-generation cementitious structural supercapacitors for resilient and energy-efficient infrastructure.