Denso Corporation

Toyota Jidosha Kabushiki Kaisha

Mitsui Chemicals, Inc.

Kazuo Ikuta

Hironori Suzuki

Masaya Nakamura

Satoru Suzuki

Hiroshi Ueshima

Daisuke Shibata

Takahiko Yamamoto

Shinichiro Kitsunai

Yasuhiro Sudou

Satoru Nagami

Shun Okijima

Norihiro Jikuri

A battery includes a positive plate, a negative plate and an insulative separator disposed between the positive plate and the negative plate. Each of the positive plate and the negative plate has a collector and an electrode layer disposed on a surface of the collector. The electrode layer contains an active material. At least one of the positive plate and the negative plate has cracks in a whole area of the electrode layer thereof or at a part of the electrode layer thereof, the part being away from a connector of the one to be coupled to an electrode at least by a predetermined distance. For example, the cracks are formed by drying the electrode layer at a predetermined drying rate.

Battery, manufacturing method of the same, and manufacturing apparatus of the same

Disclosed is method for producing a secondary battery, capable of selection of a secondary battery having a defect caused by a micro short-circuit with high accuracy. A step for producing a secondary battery includes an inspection step for selecting the secondary battery having the defect among multiple secondary batteries. In the inspection step, a short circuit resistance is calculated based on capacitances of the multiple secondary batteries calculated before self-discharge inspection, a time required for the self-discharge inspection, first and second reference voltages calculated from open circuit voltages measured before and after the self-discharge inspection in the multiple secondary batteries, and first and second voltages which are open circuit voltages of one selected from the multiple secondary batteries measured before and after the self-discharge inspection. If the short circuit resistance is equal to or lower than a predetermined standard value, the selected secondary battery is determined to have the defect.

Method for producing secondary battery

A battery separator of the invention is obtained by press forming a meltblown nonwoven fabric comprising 4-methyl-1-pentene polymer or a 4-methyl-1-pentene/&#x3b1;-olefin copolymer, the battery separator having an average fiber diameter of 0.8 to 5 &#x3bc;m, a basis weight of 9 to 30 g/m, a porosity of 30 to 60%, and a load at 5% elongation in the MD direction (longitudinal direction) of not less than 1.2 (kg/5 cm width). A lithium ion secondary battery of the invention includes the battery separator.

Separator for battery and lithium ion battery using the same

Growing community of inventors

Kariya, Japan

Kazuo Ikuta