Abstract: A method for preparing lithium-ion and lithium-ion polymer batteries to reduce water content and cell impedance. A battery having improved calendar life is prepared by electrochemically treating the activated cell by applying a voltage to the cell to react oxygen provided or trapped in the cell with moisture present as an unavoidable impurity. The electrochemical treatment of the present invention decreases the water content in the cell, thereby lowering cell impedance and extending battery life.

Abstract: A rechargeable current-generating cell is disclosed, composed of(a) an anode made of lithium or its alloys;(b) a non-aqueous electrolyte solution with a solid electrolyte or a molten electrolyte; and(c) a cathode of a vanadium-substituted alkali thiochromite having the general formula Na.sub.y Cr.sub.l-x V.sub.x S.sub.2, wherein x lies between 0.05 and 0.3 and y is 1 for the stoichiometric compound and from 0.1 to 0.4 for the non-stoichiometric one. The non-stoichiometric compound is obtained from the stoichiometric compound, by electrochemical oxidation thereof, either in the cell, after its assembly, or in a non-aqueous electrolyte solution in a separate vessel, prior to assembly of the cell. The non-stoichiometric compound can also be obtained by chemical oxidation of the stoichiometric one in a nonaqueous solution of iodine.