This proposal concerns the fabrication of a hybrid battery capacitor (HBC) using Eltron's knowledge gained in battery and capacitor research. Energy storage systems are sought for use in remote robotic systems for planetary surface operations. HBCs offer improved performance while minimizing costs. Eltron has developed two different technologies that will be combined to create a hybrid device. First, modified graphite nanofibers (MGNs) with high power density have been prepared for electrochemical capacitors. Second, Eltron has developed a patented, low-cost synthesis method for preparing high surface area LiFePO4 cathode materials. Incorporation of the MGN between the LiFePO4 particles will provide an improved electrically conductive network that will advance charge transfer throughout the electrode, improving power density, cycle lifetime, and discharge capacity. We will also partner with an electrolyte manufacturer that has proven wide temperature electrolytes that perform exceptionally well at low temperatures. In Phase I composite electrode materials will be synthesized and characterized. Lab test cells will be constructed and tested using galvanostatic (charge discharge), EIS (electrochemical impedance), and wide temperature testing methods. In Phase II we will improve the performance of our HBCs and work with a manufacturer to produce prototype cells that will be delivered to NASA.