In response to the needs of modern society and emerging ecological concerns, it is now essential to provide efficient, low-cost, and environmentally friendly electrochemical energy conversion and storage devices. These electrochemical devices are expected to have pronounced technological impact on the society - especially for powering an increasingly diverse range of portable electronic and vehicular applications. Rechargeable Lithium-ion batteries and Supercapacitors are amongst the most promising candidates in terms of their wide spread applicability, owing to their high energy and power densities. The performance of these devices depends intimately on the properties of materials used to build them. This talk will focus on the new designs and performance of the next generation of energy and power delivery devices by the use of tailored nanostructured materials and by nanoscale engineering. Some of the current challenges pertaining to the energy storage technology and the effective utilization of new electrode materials such as Si nanostructures and graphene will be discussed. Furthermore, the talk will also evaluate approaches for optimization of the Li-ion battery performance with novel designs, leading to prototype nanoscale 3D battery architectures offering improvements in energy and power density with respect to the geometrical foot print of devices.