Matsushita Electric Industrial Co., Ltd.

Jun Miyoshi

Junichi Asaoka

Ryohei Ashihara

Kikumitsu Suehiro

Kazuo Sugino

Yoji Kajikawa

Isao Kubo

Hirofumi Iwaki

Toshikazu Kaneko

Akira Ota

Yoshio Kino

Masatsugu Eri

A dry cell comprising an anode made of zinc and cathode mixture which includes manganese dioxide acting as active agent and conductor such that acetylene black having a specific surface area of 100 to 150 m.sup.2 /g measured by a BET type nitrogen gas adsorption method is used as the conductor by setting a mixing ratio in weight of the manganese dioxide to the acetylene black at 7/1 to 12/1.

Dry cell

A dry cell which is so arranged that, with a bottom plate being disposed at the lower portion of a raw cell sealed at its opening by a sealing member, an insulative seal packing is applied onto the peripheral portion of the bottom plate, while the raw cell and the peripheral portion of the bottom plate are surrounded by a metal jacket welded by laser at its butted opposite ends. At the peripheral portion of the bottom plate, a gas discharge mechanism is formed which is arranged to be normally closed by the seal packing, and to be released from the closing by the seal packing due to deformation of the bottom plate upon increase of internal pressure of the dry cell for discharging the gas within the dry cell outside, and thus, a safe dry cell free from a danger of rupture maybe provided.

The present invention provides a cylindrical alkaline battery comprising a positive electrode case of a cylindrical form having an opening at one end and accommodating an electricity-generating element comprising a positive electrode, a negative electrode, a separator and an alkaline electrolytic solution, an insulating gasket provided at the opening of the positive electrode case, a bottom plate being the negative electrode terminal provided on the gasket, and a heat-shrinkable member such as shrink tube or the like covering the outer surface of the positive electrode case. In this battery, the opening end of the positive electrode case and the outer surface of the battery extending therefrom are covered with an electrical insulating film. The presence of the electrical insulating film prevents the exterior short circuit between the positive electrode case and the bottom plate being the negative electrode terminal which may occur when the metal material of the case opening is exposed by the peeling or abnormal shrinkage of the heat-shrinkable member. The present invention also provides a cylindrical alkaline battery comprising a reinforcing washer provided between the bottom plate being the negative electrode terminal and the gasket. In this battery, electric insulation is established between the bottom plate being the negative electrode terminal and the washer or between the gasket and the washer and the presence or the electric insulation cuts off the possible electric reaction route forming a local cell and prevents the resultant leakage of the electrolytic solution.

Cylindrical alkaline batteries

A dry cell of the type enclosing therein an electrolyte mainly consisting of zinc chloride, wherein in order to ensure the more secure air- and liquid-tightness a filler or sealing agent is filled into the space between a plastic top seal and a metal top seal to seal a carbon electrode extended out of the plastic top and the upper end portion of a plastic tube covering the top surface of the plastic top seal, whereby the longer shelf life may be ensured.

Growing community of inventors

Hirakata, Japan

Jun Miyoshi