Sony Corporation

Yoshihiro Dokko

Takeshi Meguro

Hiroyuki Suzuki

Yuzuru Fukushima

Shinji Hatake

Tadashi Miebori

Noriaki Kokubu

A battery with improved safety that can more surely short-circuit electrodes when flattened out by the external force is provided. A center pin () is inserted in the center of a spirally wound electrode body formed by layering and spirally winding a cathode and an anode with a separator in between. The center pin () has a cut line () provided in the longitudinal direction and a first cutout () vertically crossing the cut line (). When flattened out by the external force, a corner () at an intersection of the cut line () and the first cutout () is projected, and short-circuit is surely generated. Further, it is preferable that the center pin () has a second cutout () in the direction perpendicular to the cut line () in a position facing the cut line () in the circumferential direction. It is also preferable that the center pin () has a cross sectional shape of an oval or an ellipse, and the cut line () is provided in a position where the diameter of the oval or the ellipse is the largest.

Battery and center pin

A battery with improved safety which can establish a short circuit between electrodes more reliably when the battery is crushed by an external force is provided. A battery includes a battery element including a cathode and an anode, a battery can containing the battery element, and a conductive short circuit member arranged in a gap between the battery element and the battery can, the short circuit member capable of biting into the battery element when the battery can is deformed.

Battery

A battery capable of preventing deformation thereof when gas is generated is provided. In the battery, a safety valve is electrically connected to a battery element, and an insulating plate is arranged between the battery element and the safety valve. The safety valve has a plurality of vent holes around a central portion thereof. The insulating plate has seven or more openings in the circumferential direction in a position where the openings can face to the vent holes of the safety valves around a central portion thereof.

A battery, which can inhibit raise of an internal resistance even when temperature change or mechanical shock is applied, and which has superior productivity is provided. A safety mechanism and a battery cover are installed at an open part of a battery case by caulking through a gasket. Inside of the battery case is sealed. A flange part of the battery cover contacts with a flange part of a safety valve of the safety mechanism. A surface roughness of the contact face is set to be in the range from about 0.5 &#x3bc;m to about 5.5 &#x3bc;m based on an arithmetic average roughness Ra. A contact resistance between the battery cover and the safety valve is thereby reduced. Further, a maximum height Ry of the contact face is preferably in the range from about 8.0 &#x3bc;m to about 50.0 &#x3bc;M.

Growing community of inventors

Fukushima, Japan

Yoshihiro Dokko