Manickam Minakshi Sundaram

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.

The idea of an economy supported by hydrogen is still being considered by government bodies and major oil companies. The extensive use of hydrogen as a fuel has many applications in pollution-free technologies which could be of every-day use in society. Examples are in transportation and power generation; other uses include chemical technology, metallurgy, effluent processing and water production. For mass application the most appropriate process for hydrogen production is water electrolysis. To this end, a simplified description of the hydrogen and oxygen evolution mechanisms is presented. Understanding these mechanisms will provide a basis for making water electrolysis more efficient. For this reason special attention is given to the design of catalysts for water electrolysis.