PURPOSE: To suppress an unusual voltage increase of a voltage drop caused during the initial discharge, irrespective of whether the discharge is carried out at a large current of a minute current, by using as a positive electrode, a sintered cupric-oxide body which is provided with a cupric oxide layer, which is formed by decomposing a cupric salt, on its surface which faces to a negative electrode.

CONSTITUTION: After 0.25g of commercially available special-grade cupric oxide power is molded with a pressure of 3ton/cm2, the molded body is sintered in an electric furnace at 850°C for one hour so as to make a cupric-oxide sintered body 1. Next, 40% aqueous copper-nitrate solution is applied to at least the surface of the sintered body 1 which faces to a negative electrode 20. After that, this is subjected to heat treatment at 500°C for 5hr so as to form a cupric-oxide layer 2 by decomposing copper nitrate, thereby obtaining a positive electrode 10. The positive eletrode 10, around which a conductive ring 3 is attached, is located on the inner surface of the bottom of a positive can 4. The negative electrode 20 is made of a roller lithium plate (diameter, 8.4mm; thickness, 1.3mm), and stuck by pressure to a negative current-collecting net 6 which is fixed to the inner surface of the bottom of a negative can 5.