SHEET ELECTRODE

PROBLEM TO BE SOLVED: To provide an electrode of high flexibility and a small short-circuit rate to all sorts of curvature by setting the 50% compression stress in the diametral direction of a loop of a sheet electrode composed of a positive electrode or a negative electrode including active substance used in a cylindrical or angular spiral battery to less than a specific value. SOLUTION: By providing such a constitution that 50% compression stress in the diametral direction of a loop of a sheet electrode is less than 0.25 g/mm, such an electrode may be obtained that even in the central part of a spiral part, no cracking may take place and cracks and chips of the active substance may hardly stick to break a separator to cause short-circuiting. When the 50% compression stress exceeds 0.25 g/mm, not only the spiral central part, but also in another area, cracking takes places to increase the short-circuiting rate. For the purpose of measuring the 50% compression stress, active substance is applied to metallic foils, dried and pressed and thus the electrode is formed in a loop shape of 40 mm diameter, and it is placed in its static state so that the diametral direction is set perpendicular to a measuring board, compressed perpendicularly by a pusher including a plane of 10 mm diameter and the compressive stress for making the loop diameter become a half of the original value is taken in account.