| 摘要 |
PROBLEM TO BE SOLVED: To enhance energy density by forming a recessed part and/or a projecting part into a linear pattern on at least one surface of a battery case. SOLUTION: This battery case 24 of a secondary battery 25 storing an electrode layered product formed by winning or laminating a positive electrode and a negative electrode in a mutually insulated state is composed of a battery can 10 and a battery lid 7 for sealing a maximum opening part. The maximum opening part of the battery can 10 is sealed by the battery lid 7, having the positive electrode terminal 6, and the battery lid 7, is provided in the direction to laminate the electrode layered product. A X-shaped groove part 10a crossing in a X-shape is formed on the outer surface in the direction to laminate the electrode along the diagonal line within the surface, from among the surfaces which the battery can 10 has, and a X-shaped groove part 7a having a similar X-shaped pattern is formed on the outer surface of the battery lid 7. In comparison with a flat and rectangular battery which has no X-shaped groove part, this flat and rectangular battery having a X-shaped groove part makes the adhesion between electrodes satisfactory, lessens the increase in battery thickness without reducing the input quantity of an element electrode active material, and also reduces the battery impedance. |
