An lithium-iodine electrochemical cell and method of making is described. The cell comprises a lithium anode and a cathode of a charge transfer complex which includes iodine and preferably polyvinylpyridine. The iodine-containing cathode is in operative contact with both the anode the cell casing serving as the cathode current collector. Preferably the casing is composed of stainless steel that has been thermally annealed at temperatures of 1,800° F. or less. The annealed stainless steel has a grain size of about ASTM 7 or finer. When the iodine-containing cathode material in liquid form is filled into the casing, it contacts the inner casing surface. The passivation layer that subsequently forms at the contact interface affects cell impedance during discharge. It is desirable to maintain the internal impedance as low as possible.