Battery Bus Bar Weak-Link Structure for Cell Venting Protection
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Solution Overview
Problem
The bus bar in existing cylindrical battery designs hinders the pressure relief efficiency of the pressure relief valve, leading to slower pressure relief and increased risk of thermal runaway, and fails to provide timely short-circuit protection.
Innovation Solution
A bus bar design with weak parts at the joints of the conductive sheets, positioned to face the thinning area of the pressure relief valve, allowing the valve to break and disconnect the circuit loop upon pressure relief, providing simultaneous internal pressure relief and short-circuit protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bus bar connects the positive and negative electrodes through welding, then the electrical connection is established, but the pressure relief efficiency is hindered and short-circuit protection is not provided
Solution Approach 1:
The bus bar is divided into multiple conductive sheets with weak parts at the joints. This segmentation allows the bus bar to be easily broken at predetermined locations to achieve pressure relief and short-circuit protection, resolving the contradiction between maintaining structural integrity for electrical connection and enabling easy disruption for safety functions.
Solution Approach 2:
Weak parts are pre-formed at the joints of the conductive sheets during manufacturing. These preliminary weak structures are positioned to face the thinning area of the pressure relief valve, so that when pressure builds up, the valve can efficiently break through and disconnect the circuit loop, achieving both pressure relief and short-circuit protection without requiring complex additional mechanisms.
2Power
If the bus bar is designed to connect cells in series and parallel, then power transmission is achieved, but thermal runaway risk increases due to delayed pressure relief
Solution Approach 1:
The harmful function of the bus bar is extracted and converted into a protective function. By positioning weak parts at the joints to face the pressure relief valve's thinning area, the bus bar structure itself becomes part of the safety mechanism, disconnecting the circuit loop when pressure relief occurs, thereby reducing thermal runaway risk while maintaining power transmission capability.
Solution Approach 2:
The potential harm of the bus bar hindering pressure relief is converted into a benefit by designing weak parts that facilitate easy disconnection. The same structural feature that could impede pressure relief becomes the mechanism for achieving both pressure relief and short-circuit protection, turning a harmful effect into a protective function.
3Speed
If the pressure relief valve is provided with a thinning area, then pressure relief is enabled, but the circuit connection remains intact allowing short-circuit propagation
Solution Approach 1:
The pressure relief function and short-circuit protection function are merged into a single integrated mechanism. The weak parts at the bus bar joints are positioned to face the thinning area of the pressure relief valve, so that when the valve breaks through during pressure relief, it simultaneously disconnects the circuit loop, achieving both functions at once and preventing short-circuit 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
Ensures efficient pressure relief and timely short-circuit protection, enhancing thermal and electrical safety by synchronously achieving double protection against pressure and short-circuit events.
Implementation Method 1
the pressure relief valve is provided with a thinning area configured to be burst when pressure is released
Implementation Method 2
the first weak part and the second weak part are broken by a strong impact force when the thinning area is burst
Implementation Method 3
the first weak part and the second weak part are fused by overcurrent when subjected to a strong current
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Disclosed are a bus bar, a battery module, and a battery pack. The bus bar includes at least two conductive sheets (2). By setting the first weak part (230) and the second weak part (240) above the thinning area (131), when pressure is released, the thinning area (131) is first broken by the high-pressure gas in the cells (1), and the impact force breaks the first weak part (230) and the second weak part (240), thereby enabling the pressure relief valve (13) to relieve pressure efficiently and smoothly. Moreover, while the first weak part (230) and the second weak part (240) are broken, the circuit connection between two adjacent cells (1) is also disconnected, thereby achieving short-circuit protection, and finally achieving a double protection of pressure relief protection and cell short-circuit protection synchronously.