Engineered Nanomaterials for Energy Harvesting and Storage Applications
Ajayan, Pulickel M
Doctor of Philosophy
Energy harvesting and storage are independent mechanisms, each having their own significance in the energy cycle. Energy is generally harvested from temperature variations, mechanical vibrations and other phenomena which are inherently sporadic in nature, harvested energy stands a better chance of efficient utilization if it can be stored and used later, depending on the demand. In essence a comprehensive device that can harness power from surrounding environment and provide a steady and reliable source of energy would be ideal. Towards realizing such a system, for the harvesting component, a piezoelectric nano-composite material consisting of ZnO nanostructures embedded into the matrix of ‘Paper’ has been developed. Providing a flexible backbone to a brittle material makes it a robust architecture. Energy harvesting by scavenging both mechanical and thermal fluctuations using this flexible nano-composite is discussed in this thesis. On the energy storage front, Graphene based materials developed with a focus towards realizing ultra-thin lithium ion batteries and supercapacitors are introduced. Efforts for enhancing the energy storage performance of such graphitic carbon are detailed. Increasing the rate capability by direct CVD synthesis of graphene on current collectors, enhancing its electrochemical capacity through doping and engineering 3D metallic structures to increase the areal energy density have been studied.