The excellent results were obtained with LiV3O8 treated by water as a cathode material for rechargeable lithium cells [1]. West at al. [2] performed parallel study on KV3O8 and K3V5O13. They found that insertion of a considerable amount of lithium ions might occur in the structure of KV3O8 but using low current rate. In contrast to LiV3O8, which is the only existing phase in the equilibrium phase diagram between V2O5 and LiVO3 [3], four different phases K3V5O14, KV3O8, K2V8O21 and KV5O13 are distinguished in the phase diagram between V2O5 and KVO3 [3]. The electrochemical behavior of those four phases was studied in [4] and it was established a very good performance of the two poor of potassium phases. On the basis of the fact that the structure of the potassium vanadates is layered as the LiV3O8 one, the same preliminary treatment by water [1] was applied to those compounds.
