Battery Cell Current Interrupt Device Prevents Tab Reconnection
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Solution Overview
Problem
Pouch-type battery cells fail to completely block current flow when over-charged, as the disconnected lead tab reconnects with the electrode assembly upon pouch shrinkage, potentially leading to further charging and safety hazards like ignition or explosion.
Innovation Solution
A battery cell design incorporating a current interrupt device with a fusing unit and notch in the lead tab, which separates from the electrode tab during pouch expansion and remains disconnected even when the pouch returns to its original shape, using an insulating layer to prevent reconnection and ensure continuous current blockage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pouch expands during abnormal conditions to separate the lead tab and electrode tab, then current flow is blocked, but when the pouch shrinks back to its original position, the lead tab and electrode tab reconnect, allowing current to flow again
Solution Approach 1:
The lead tab is divided into multiple segments: a first lead tab portion, a second lead tab portion, and an insulating layer positioned between them. This segmentation ensures that when the pouch expands, the separation creates a reliable current break, and when the pouch shrinks, the insulating layer prevents reconnection between the separated lead tab portions.
Solution Approach 2:
An insulating layer is introduced as an intermediary element between the first and second lead tab portions. This insulating layer acts as a mediator that physically prevents the lead tab portions from reconnecting when the pouch returns to its original shape, ensuring continuous current blocking without requiring permanent structural changes to the pouch or tabs.
2Reliability
If the lead tab is designed to disconnect during pouch expansion, then current flow is interrupted, but the simple structure allows reconnection when the pouch shrinks
Solution Approach 1:
The insulating layer is integrated with the lead tab structure, forming a unified current interrupt device. The first and second lead tab portions are connected through this insulating layer configuration, creating a compact design that combines the disconnection function with the insulating barrier in a single integrated structure rather than separate components.
Solution Approach 2:
The current interrupt device utilizes changes in the physical state and positioning of the lead tab portions relative to each other. When the pouch expands, the distance between lead tab portions increases, creating current interruption. The insulating layer maintains this parameter change (separation distance) even when the pouch shrinks, preventing reconnection without requiring complex mechanical locking mechanisms.
3Shape
If the pouch material is thin and flexible allowing shrinkage back to original position, then the battery structure remains compact, but the lead tab reconnects with the electrode assembly causing safety hazards
Solution Approach 1:
The insulating layer serves as a permanent intermediary barrier between the lead tab portions. Even when the thin flexible pouch shrinks back to its original position, this insulating layer prevents direct contact and reconnection between the lead tab and electrode assembly, eliminating the safety hazard while preserving the pouch's compact shape and flexibility.
Solution Approach 2:
The lead tab structure is segmented into portions that are separated by the insulating layer. This segmentation ensures that the thin flexible pouch can shrink without causing reconnection, as the insulating barrier maintains the separation between lead tab portions regardless of pouch shape changes, preventing harmful reconnection while allowing compact form factor.
Data Source
AI summary
The present disclosure relates to a battery cell. The battery cell includes: an electrode assembly; a pouch which wraps around the electrode assembly; an electrode tab extended from the electrode assembly; a lead tab attached to the electrode tab; and a current interrupt device which is configured to block reconnection of the lead tab and the electrode tab when the pouch is shrunk to return to an original position after being expanded, while blocking current flow by separating the lead tab and the electrode tab through the expansion of the pouch, when abnormal situation of battery cell occurs.