Square Battery Insulator Fold Structure for Swelling Clearance
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Solution Overview
Problem
Existing square sealed secondary batteries face issues with insertion failures of the electrode body into the insulating member and reduced long-term reliability due to tensile stress on the insulating member during charge/discharge cycles.
Innovation Solution
A square secondary battery design with a conductive container, lid, and insulating member formed in a rectangular parallelepiped shape, where at least one side surface opposing the electrodes is folded to create a separation direction, allowing for a clearance between the charge/discharge body and the insulating member, preventing insertion failures and alleviating tensile stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the insulating member is made smaller than the electrode body to reduce interference, then interference between insulating member and outer can is reduced, but insertion failure occurs readily resulting in low yield
Solution Approach 1:
The insulating member incorporates a folded portion that allows dynamic adjustment of its dimensions. During charge/discharge cycles, the folded portion can expand or contract to accommodate electrode body swelling while maintaining proper clearance with the outer can, thus preventing both interference and insertion failure
Solution Approach 2:
The insulating member's effective size is changed through the folded portion configuration. By controlling the fold depth and position, the insulating member can maintain an optimal size relationship with the electrode body - small enough to prevent interference with the outer can but large enough to allow reliable insertion
2Quantity of substance
If the insulating member is made smaller to fit the electrode body, then material usage is reduced, but tensile stress is generated on the insulating member when the electrode body swells resulting in reduced long-term reliability
Solution Approach 1:
The folded portion acts as a dynamic buffer that absorbs expansion forces. When the electrode body swells during charging, the folded portion can unfold or expand to accommodate the volume increase, preventing tensile stress concentration that would compromise long-term reliability
Solution Approach 2:
The folded portion is pre-configured to provide cushioning capacity before swelling occurs. This predetermined structural feature ensures that when electrode expansion happens, there is already sufficient buffer space and structural flexibility to absorb the stress without damaging the insulating member
Data Source
AI summary
A square secondary battery, including: a conductive container which is formed in a rectangular parallelepiped shape opened on one surface side; a lid which seals the one surface side of the container; a charge/discharge body which is housed in the container and which has electrodes respectively formed on both sides in a width direction; and an insulating member which coats the charge/discharge body and which insulates the charge/discharge body and the container from each other, wherein the insulating member is formed in a rectangular parallelepiped shape opened on one surface side and at least one side surface among a pair of side surfaces respectively opposing the electrodes of the charge/discharge body is folded in a direction of separation from the charge/discharge body along a height direction.