The broader impact/commercial potential of this project is the introduction of new generation energy storage devices that are mechanically strong, highly flexible, and high energy density. The proposed novel flexible cathode electrode technology holds the key to commercialize high performance flexible batteries. If successful, the proposed research program will generate critical knowledge for fabricating a high-energy and high-power cathode for flexible energy storage device. It is anticipated that the proposed cathode electrode materials may improve the energy density of current state-of-the-art flexible battery at least by a factor of 5. The significant enhancement in energy density and power density makes the proposed technology attractive to new markets where flexible batteries hav not been widely used. Additionally, the proposed technique and concept may be used for manufacturing other multifunctional materials for a wide range of different applications. This Small Business Innovation Research Phase I project aims at the development of novel flexible cathode materials for flexible electronics. Mechanical strength of flexible electrodes is the most critical property. Traditional approach to achieve mechanically strong electrodes is to deposit active materials on a flexible carbon-based substrate, while the performance of resulting electrodes strongly are affected by the active material/substrate interface, which is often hard to fabricate and control. The key innovation of the proposed research is a core-shell nano-architecture, in which a thin carbon layer is uniformly coated on the cathode nanofibers through an in-situ formation process. The core-shell nano-architecture design allows us to achieve enhanced mechanical strength, structural integrity, and electronic conductivity simultaneously. In the meantime, the employment of high voltage, high capacity cathode nanofibers as the core will ensure the high power and energy densities of resulting cathode electrodes.