There is a need for high energy (~ 200 Wh/kg) and high power (> 500 W/kg) density rechargeable Li-ion batteries that are safe and reliable for several space and consumer applications. State-of-the-art rechargeable Li-ion batteries are incapable of fulfilling these stringent requirements. We propose to develop high energy and power density nanocomposite cathodes that will lead to thermally stable, high energy and power density Li-ion batteries. Working in collaboration with a leading developer of Li-ion polymer batteries, in Phase I, we will demonstrate that it is possible to produce a stable and high power density nanostructured cathode, along with good energy density. As part of Phase I work, the electrochemical properties of these nanostructured cathodes will be evaluated in Li and Li-ion test cells with a liquid electrolyte. In Phase II, prototype batteries will be fabricated and tested for performance, along with the optimization and scaling of the nanocomposite synthesis process.