V.sub.2O.sub.5 electrodes with high power and energy densities

Methods are provided for forming films of orthorhombic V.sub.2O.sub.5. Additionally provided are the orthorhombic V.sub.2O.sub.5 films themselves, as well as batteries incorporating the films as cathode materials. The methods use electrodeposition from a precursor solution to form a V.sub.2O.sub.5 sol gel on a substrate. The V.sub.2O.sub.5 gel can be annealed to provide an orthorhombic V.sub.2O.sub.5 film on the substrate. The V.sub.2O.sub.5 film can be freestanding such that it can be removed from the substrate and integrated without binders or conductive filler into a battery as a cathode element. Due to the improved intercalation properties of the orthorhombic V.sub.2O.sub.5 films, batteries formed using the V.sub.2O.sub.5 films have extraordinarily high energy density, power density, and capacity.