Suitable electrode materials for hybrid capacitors

Li- and Na-ion batteries and supercapacitors are finding applications for electrical energy storage for power grid stabilization, domestic and utility renewable energy storage, and high energy density applications such as transportation, entertainment, and computing. Major challenges in the use of these systems include cost, safety, and environmental impact. Cost is generally tied to the electrode materials and the electrolytes used. Safety issues mainly arise from the thermal stability and toxicity of the materials used. Environmental issues are related to the origin of materials used and the issues associated with their recycling/disposal. This chapter provides an overview of the importance of hybrid supercapacitors, and a comprehensive summary of research on electrode materials and requirements placed on using composite electrodes for this system. An emphasis is placed on the synergistic effects of the raw material composites on the performance characteristics of supercapacitors.