Sealed rechargeable battery and manufacturing method of the same

Abstract

A sealed rechargeable battery containing an electrode unit and a liquid electrolyte in a metallic case with a bottom that is sealed with a closure assembly. The electrode unit includes a positive electrode and a negative electrode, each made up of a collector and electrode material paste coated thereon, wound around with a separator interposed therebetween. The closure assembly includes a metallic filter that forms an internal terminal and accommodates a safety mechanism provided in case of abnormal pressure rise caused by overcharging etc, a resin inner gasket, and a metallic cap that forms an external terminal superposed upon one another. A resin inner gasket is attached to the metallic filter and the end edge of the metallic filter is crimped to provide a seal. The metallic filter and all the metallic parts encased in the metallic filter are joined together by welding. This closure assembly design enables high power output and high-current discharge of the battery with low resistance.

Description

technical field [0001] The present invention relates to a sealed secondary battery suitable for a driving power supply, and more particularly to a sealed secondary battery having a low impedance and a sealing plate structure suitable for large current discharge, and a method for manufacturing the same. Background technique [0002] Among sealed secondary batteries, lithium-ion secondary batteries are used in a variety of applications due to their light weight, small size, and high energy density, ranging from consumer equipment represented by mobile phones to electric vehicles and electric Power supply for driving tools, etc. Especially in recent years, it has attracted much attention as a power supply for driving, and research towards high energy density and high output power is in the ascendant. The sealing plate of the lithium-ion secondary battery used in the current civilian equipment generally has the structure shown in FIG. 4 . Inside the metal filter 19 constitutin...

AI Technical Summary

Problems solved by technology

[0005] However, the problem to be solved for the sealing plate of the lithium ion secondary battery used in consumer equipment is that as the inner liner for sealing by caulking the metal filter, a molded liner made of synthetic resin such as polypropylene is usually used. Under the action of factors such as drop, vibration, and high temperature storage, the resin inner liner will cause a decrease in elastic force over time, which will lead to a decrease in caulking force, thereby reducing the contact resistance of internal parts. increase

[0006] In addition, the problem with the structure of JP-A-2000-90892 is that since the metal thin-walled valve body is not installed, the excessive current path cannot be blocked when the battery is mistakenly overcharged, etc., so the electrolytic The rapid decomposition of liquid and electrode active material is further promoted, causing the temperature of the battery to rise, which develops into a situation where gas is emitted

[0007] Furthermore, the problem with the structure of JP-A-2001-126695 is that although a part of the safety valve member and the metal cap are welded together, most of the sealing plate is mechanically joined together by caulking. Therefore, under the action of factors such as drop, vibration, and high-temperature storage, the caulking force will decrease with time, which will increase the contact resistance of internal parts, which will lead to an increase in the internal resistance of the battery.

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