Abstract: A battery case (1, 8), substantially square in cross section, has four lateral walls (5, 6) each of which is gradually arc-shaped to expand outwardly with a radius of curvature R1. The cross section is adapted to satisfy equation R1/r=4 to 20, where r is the distance between a midpoint (C2) of each lateral wall (5, 6) and the center point (C1) in the cross section of the battery case (1, 8) and R1 is the radius of curvature. In addition, the battery case (8) is rounded at each corner with a radius of curvature of R2, and has a cross section that satisfies equation R2/r=0.3 to 0.8, where r is the distance between the midpoint (C2) of each lateral wall (6) and the center point (C1) in the cross section of the battery case (8) and R2 is the radius of curvature of each corner.

Abstract: A battery electrode plate (19) is produced via an active material impregnation step for impregnating an entire porous core substrate shaped like a thin plate (1) with an active material (3), a pressing step for performing press working on the core substrate to form a plurality of rail shaped protrusions (8), an active material removal step for removing the active material to form core substrate exposed sections (13) by applying ultrasonic vibrations to the rail shaped protrusions, a flattening step for compressing the core substrate exposed sections down to an identical level with the other sections, and a cutting step for cutting predetermined sections including the core substrate exposed sections.

Abstract: A conveying holder for cylindrical cell is provided which is capable of stably supporting a cylindrical cell irrespective of variation in outer diameter of the cell or impact during transfer. An outer wall member 20 of which inner diameter is greater than the diameter of a cylindrical cell 7 is provided. A plurality of elastic inner wall portions 21 are concentrically arranged to have a distance from the inner side of the outer wall member 20, each elastic inner wall portion joined at both ends to the outer wall member 20. A cell holding portion 22 is provided projecting inwardly from the inner side of each elastic inner wall portion 21 and having a cell holding surface 29 thereof corresponding in shape to the outer side of the cylindrical cell 7. The cell holding surfaces 29 are arranged along a concentric circle which is smaller in diameter than the cylindrical cell 7 so that they can hold the cylindrical cell 7 in-between under pressure.