The use of renewable energy with unsteady supply has been gradually increased, requiring energy storage for steady supply of energy. Carbonaceous materials such as graphene, carbon nanotubes, and carbon fibers have been studied for capacitive energy storage purposes. On the other hand, materials based on metal oxides/sulfides have been studied for electrochemical charge storage. Though the carbonaceous materials carry large surface area and high electrical conductivity, they have limited energy density. However, the metal oxides/sulfides perform electrochemical reactions, resulting in high energy density. Composites of carbonaceous materials and metal oxides/sulfides exhibit the synergistic effects on energy density and power density, improving the supercapacitor performances tremendously. We have tried several different carbon materials, metals, and particle sizes, synthetic methods, morphologies, etc., for better performances up to 4000 F g^-1. Recently, we have developed carbon nano-onions and doped carbon nano-onions in inexpensive way for making remarkably capacitive materials.