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

制备了阳离子交换五氧化二钒干凝胶（VXG），并将其用作锂离子二次电池正极材料。原始VXG中的质子可以被交换成钠（Na^+）、钙（Ca^<2+>）和镧（La^<3+>）。这些阳离子交换的VXG的层间距大于原始VXG的层间距。去除阳离子交换的VXG中的水分子导致层间距的收缩。由于Na^+、Ca^2+和La^3+的离子半径相近，脱水阳离子交换的VXG的层间距约为0.89 nm。电化学插入到阳离子交换的VXG的锂的程度大于原始VXG，可能是由于层间距离的扩大，这可能会增强锂在VXG中的扩散。由于其他阳离子交换VXG中锂容纳位点的数量最多，因此La交换VXG中观察到的锂含量最大。

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.