Investigation of cation-exchanged vanadium pentoxide xerogels as the cathode materials for lithium rechargeable battery

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Cation-exchanged vanadium pentoxide xerogels (VXG) have been prepared and investigated as the cathode materials for rechargeable lithium battery. The protons included in original VXG could be exchanged to sodium (Na^+), calcium (Ca^<2+>) and lanthanum (La^<3+>). The interlayer distances of these cation-exchanged VXG's were larger than that of original VXG. Removal of water molecules in the cation-exchanged VXG's resulted in shrinkage of the interlayer distances. The interlayer distances of the dehydrated cation-exchanged VXG's were 〜0.89 nm since the ionic radii of Na^+, Ca^<2+> and La^<3+> are close to each other.Thin film electrodes of the cation-exchanged VXG's were prepared to perform the electrochemical insertion of lithium. The extent of lithium inserted electrochemically into the cation-exchanged VXG's was larger than that for original VXG, probably due to the enlargement of the interlayer distance, which may enhance the diffusion of lithium in VXG. The largest extent of lithium was observed for La-exchenaged VXG since the number of lithium accommodating sites was the largest in other cation-exchanged VXG's.