Wound Electrode Collector Slit to Prevent Terminal Detachment
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Solution Overview
Problem
The existing connection structure of secondary batteries, which involves squashing the side edge portion of the collector wound portion to form a collector bundle, can lead to detachment of the collector bundle or collector terminal due to strong tension, resulting in defective products and reduced yield.
Innovation Solution
A secondary battery configuration that includes an elongated slit formed between the collector bundle and the core portion, preventing tension from acting on the collectors between these components, thereby reducing the likelihood of collector breakage and detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the side edge portion of the collector wound portion is squashed to form a collector bundle, then a favorable conductive path of low electric resistance is formed, but strong tension is exerted on the collectors which may cause breakage and detachment of the collector bundle or terminal
Solution Approach 1:
The collector wound portion is divided into two separate portions by introducing a separation line, creating a first collector wound portion for forming the collector bundle and a second collector wound portion that remains separate. This segmentation prevents the strong tension that causes collector breakage while maintaining the conductive path quality through the bundled portion.
Solution Approach 2:
The second collector wound portion is extracted or separated from the first collector wound portion by forming a separation line between them. This extracted portion is not squashed into the collector bundle, thereby eliminating the source of strong tension that would otherwise act on the collectors during bundle formation.
2Ease of manufacture
If the collectors are gathered to form a collector bundle, then a low electric resistance connection is achieved, but the collectors are subjected to strong tension that exceeds their strength and causes large breaks
Solution Approach 1:
The collector wound portion is segmented into a first portion that is gathered into the collector bundle and a second portion that is separated by a separation line. This segmentation allows the bundle to be formed with adequate collector contact for low resistance while preventing the excessive tension that would cause manufacturing defects.
3Reliability
If the collectors are brought into close contact to form a collector bundle, then electrical connection is improved, but slight scratches may spread and grow into large breaks during subsequent steps
Solution Approach 1:
By segmenting the collector wound portion and separating the second portion from the first, the structure stabilizes the collectors that are brought into close contact for electrical connection. The separation prevents tension-induced propagation of scratches that would otherwise occur during subsequent manufacturing steps.
Data Source
AI summary
The present disclosure provides a technology for preventing detachment of a collector bundle or a collector terminal derived from collector breakage. A wound electrode body of the secondary battery disclosed herein includes: a core portion in which electrode mix layers of electrode sheets face each other; a collector wound portion resulting from winding of uncoated portions of the electrode sheets; and a collector bundle which is formed in a partial region of the collector wound portion, and to which a collector terminal is connected. Furthermore, in the wound electrode body, an elongated slit is formed running through the collector wound portion, and extending continuously so as to conform to the collector bundle, between the collector bundle and the core portion. In consequence it becomes possible to prevent large breaks such that the collector bundle or the collector terminal comes off.