*** 9761626 Welker This Small Business Innovation Research Phase I project proposes a novel solid polymer electrolyte (SPE) that will more than quadruple the practical power, peak power, and energy density of state-of-the-art secondary lithium batteries. The innovation involves the controlled incorporation of substituted sidechains onto dendritic carbosilane polymers. Covalently attaching these high performance SPEs to high energy density fibrous electrodes will produce secondary lithium batteries with substantially increased energy densities and power densities. These novel electrolytes combine the beneficial aspects of SPEs and liquid electrolytes with other desirable features not found in either system. The innovations will enable higher power capabilities that arise from higher cell voltages, higher conductivities, higher transference numbers, lower interfacial impedance, and more complete utilization of the electrode capacity - all at a reasonable cost. This program will result in significant improvements in power density, energy density, cycle life, safety, disposal, and cost. Improved lithium polymer batteries would find a large market in electric vehicles, and consumer products, as well as in military applications. ***