Materials of Supercapacitor: Applications and Developments

Supercapacitors (SCs), also known as electrochemical capacitors, have emerged as promising energy storage devices due to their high-power density, rapid charge–discharge capabilities, and long cycle life. Central to their performance is the selection and optimization of materials used in electrodes, electrolytes, separators, and current collectors. This article presents a comprehensive review of the latest advancements in supercapacitor materials, focusing on carbon-based structures, metal oxides, conducting polymers, and emerging hybrid composites. The role of electrolytes—aqueous, organic, and ionic liquids—in determining the electrochemical window and overall device efficiency is also discussed. Furthermore, the article explores recent trends such as nanostructuring, sustainable material synthesis, and solid-state supercapacitor design. Applications of SCs across portable electronics, electric vehicles, renewable energy systems, and grid storage are examined in detail. Finally, the paper identifies existing challenges in enhancing energy density, mechanical stability, and cost-effectiveness, and highlights future perspectives including the use of AI-assisted material discovery and hybrid energy system integration.