Supercapacitors have emerged as promising energy storage devices due to their high power density, rapid charge–discharge capability, and long cycle life. Among various electrode materials, carbon-based materials and metal oxides have gained significant attention for their complementary electrochemical properties. Carbon materials, such as graphene, carbon nanotubes, and activated carbon, provide excellent electrical conductivity, large surface area, and stability, while metal oxides, including manganese dioxide, Co3O4, nickel oxide, and ruthenium oxide, offer high pseudocapacitance through redox reactions. The combination of these materials in hybrid electrode structures enhances energy density, rate capability, and overall electrochemical performance. This review provides a comprehensive analysis of recent advancements in carbon/metal oxide composite electrodes for supercapacitors, focusing on synthesis methods, structural optimization, charge storage mechanisms, and electrochemical performance. In addition, challenges such as material stability, scalability, and cost-effectiveness are discussed, along with potential strategies for future improvements. The integration of nanostructured carbon-metal oxide hybrids presents a viable approach for developing next-generation supercapacitors with enhanced energy storage capabilities for various applications, including portable electronics, electric vehicles, and renewable energy systems.
Gairola et al. (2026) studied this question.