Secondary Battery Fusing Portions for Thermal Runaway Isolation
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Solution Overview
Problem
In secondary batteries, thermal runaway can occur due to internal short circuits, causing cumulative heat and temperature rise, as the transition portion between the tab and electrode terminal connections fails to disconnect the electrical circuit between cells, leading to reverse charging and increased heat generation.
Innovation Solution
The secondary battery design includes connecting pieces with tab electrical connecting portions, electrode terminal connecting portions, and fusing portions, where the fusing portions are narrower than the electrode terminal connecting portions, allowing for quick disconnection of the electrical connection between a faulty cell and the cap plate when an internal short circuit occurs, thereby preventing thermal runaway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transition portion is used to connect tab electrical connecting portion and electrode terminal electrical connecting portion, then electrical connection is established, but the transition portion cannot disconnect the electrical circuit between cells during thermal runaway, leading to cumulative heat and temperature rise
Solution Approach 1:
The connecting piece is segmented into distinct functional portions: tab electrical connecting portion, transition portion, and electrode terminal electrical connecting portion. Each portion has a specific width designed for its function, with the transition portion being narrower to serve as a sacrificial element that can be disconnected during thermal runaway, isolating the harmful effects between cells
Solution Approach 2:
The transition portion is extracted as a separate, removable element between the tab electrical connecting portion and electrode terminal electrical connecting portion. This extracted transition portion acts as a disconnectable link that can be熔断 (fused) to break the electrical circuit between cells during thermal runaway, preventing cumulative heat propagation
2Stability of the object's composition
If the transition portion is designed with sufficient width for stable connection, then connection stability is improved, but the transition portion cannot be easily fused to disconnect the electrical circuit during internal short circuit
Solution Approach 1:
Different portions of the connecting piece have different local qualities in terms of width and melting characteristics. The transition portion has a narrower width and is designed to be the weakest link, making it susceptible to fusion during thermal runaway while maintaining stable connection under normal operating conditions
3Quantity of substance
If cells are electrically connected in parallel to increase capacity, then battery capacity is improved, but thermal runaway in one cell can affect other cells through reverse charging and cumulative heat
Solution Approach 1:
The connecting piece is pre-designed with a transition portion that has specific dimensional characteristics (narrower width) before thermal runaway occurs. This preliminary design ensures that during thermal runaway, the transition portion will be the first to fuse, automatically disconnecting the electrical circuit between cells and preventing thermal runaway propagation
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
This design reduces cumulative heat and temperature rise by isolating the affected cell, minimizing the impact of other cells and reducing failure probability by swiftly cutting off electrical connections during internal short circuits.
Implementation Method 1
the fusing portions are the same as the tab electrical connecting portions in number, each fusing portion electrically connects the corresponding tab electrical connecting portion to the electrode terminal electrical connecting portion, a width of each fusing portion is less than a width of the electrode terminal electrical connecting portion
Data Source
AI summary
The present disclosure provides a secondary battery, which comprises a cap plate, at least two cells and two connecting pieces. The cap plate is provided with two electrode terminals which are opposite in electrical polarity. Each cell has two tabs which are opposite in electrical polarity. Each connecting piece has: an electrode terminal electrical connecting portion for electrically connecting with the corresponding electrode terminal of the cap plate; a plurality of tab electrical connecting portions for electrically connecting with the corresponding tabs of the cells respectively; and a plurality of fusing portions electrically connecting the corresponding tab electrical connecting portion to the electrode terminal electrical connecting portion, a width of each fusing portion is less than a width of the electrode terminal electrical connecting portion. A configuration of the connecting piece is simple, thereby reducing the cumulative heat of the secondary battery and reducing the temperature rise.