Secondary Battery Terminal Cut-Off Mechanism for External Short-Circuit Protection
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Solution Overview
Problem
Existing secondary battery configurations face challenges in efficiently cutting off current flow when externally short-circuited, leading to potential damage, particularly when multiple batteries are arranged in a pack, as existing solutions require large-scale current cut-off mechanisms that increase manufacturing costs and space requirements.
Innovation Solution
A secondary battery design incorporating a cut-off portion that switches from a grounded state to a cut-off state upon deformation by heat generated from a short-circuit current, utilizing a melting member and insulating member arranged between the terminal and casing, or a configuration of metal layers with different linear expansion coefficients to increase contact resistance and prevent current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current cut-off mechanism is provided between the casings of secondary batteries or to span adjacent casings, then external short-circuit protection is improved, but the mechanism becomes large-scaled and manufacturing cost increases
Solution Approach 1:
The patent extracts the current cut-off function from a separate external mechanism and integrates it into the terminal structure itself. The cut-off portion is formed as an integral part of the terminal, eliminating the need for large-scale external current cut-off mechanisms between casings. This integration maintains protection reliability while significantly reducing mechanism size and manufacturing cost.
Solution Approach 2:
The cut-off portion acts as an intermediary element within the terminal structure that provides current cut-off protection. Instead of requiring direct interaction between adjacent battery casings, the cut-off portion mediates the protection function by being deformed by heat from short-circuit current, thereby electrically disconnecting the terminal from the casing internally rather than requiring external mechanisms.
2Reliability
If a large-scaled current cut-off mechanism is provided to span casings, then external short-circuit protection is improved, but installation space increases
Solution Approach 1:
The cut-off portion is nested within the terminal structure, specifically formed as part of the current collecting member. This nesting approach allows the current cut-off protection mechanism to be housed within the existing terminal volume without requiring additional installation space between or around battery casings, thereby maintaining protection reliability while minimizing space consumption.
Solution Approach 2:
Instead of implementing current cut-off protection in the external space between casings, the patent transitions to an internal dimension by forming the cut-off portion within the terminal structure itself. This dimensional transition from external to internal space utilization enables protection without increasing installation volume.
3Ease of manufacture
If a simple configuration is used for current cut-off, then manufacturing cost is reduced, but external short-circuit protection may be insufficient
Solution Approach 1:
The patent merges the current cut-off function with the terminal structure by forming the cut-off portion as an integral part of the current collecting member. This merging eliminates the need for separate, complex external cut-off mechanisms while maintaining effective protection. The simplified integrated configuration reduces manufacturing steps and costs while ensuring reliable current interruption when short-circuit current heats and deforms the cut-off portion.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution effectively cuts off current flow between the terminal and casing upon external short-circuiting, preventing battery damage while simplifying the configuration and reducing installation space, allowing for a more compact and cost-effective design.
Implementation Method 1
the cut-off portion switches from the grounded state to the cut-off state by being deformed by heat generated as a short-circuit current flows
Implementation Method 2
the cut-off portion switches from the grounded state to the cut-off state by being deformed by heat generated as a short-circuit current flows
Implementation Method 3
the melting member melts by the heat generated as the short-circuit current flows to the cut-off portion when the casing is externally short-circuited
Implementation Method 4
the melting member melts by the heat generated as the short-circuit current flows to the cut-off portion
Implementation Method 5
a configuration of metal layers with different linear expansion coefficients to increase contact resistance and prevent current flow
Data Source
AI summary
A secondary battery includes: a battery element; a casing which accommodates the battery element; a positive electrode terminal and a negative electrode terminal provided to the casing and electrically connected to the battery element; and a cut-off portion which switches from a grounded state in which the casing and one terminal of the positive electrode terminal and the negative electrode terminal have an identical potential, to a cut-off state in which the casing and the one terminal are electrically cut off. The one terminal has a facing portion which faces the casing, and the cut-off portion is arranged between the facing portion and the casing. When the casing is externally short-circuited, the cut-off portion switches from the grounded state to the cut-off state by being deformed by heat generated as a short-circuit current flows.