Battery Module Short-Circuit Unit for Overcharge Safety
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Solution Overview
Problem
Conventional battery modules face challenges in preventing overcharge, as existing safety systems struggle to reliably cut current when battery expansion occurs, leading to potential explosions and ignition, and can also interrupt normal operation.
Innovation Solution
A battery module design featuring a cell stack with first and second bus bars of opposite polarities, a short-circuit unit that connects these bus bars via an expanding force due to swelling, and a cartridge accommodating the bus bars and short-circuit unit, including an elastic member and stoppers to generate a short circuit and break a breaking portion to stop charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protection circuit is used to cut current at overcharge, overdischarge or overcurrent, then safety is improved, but the system complexity increases
Solution Approach 1:
The battery module's own physical response (expansion during overcharge) is utilized to trigger the safety mechanism. The short-circuit unit is positioned such that abnormal battery expansion directly causes the short-circuit terminal to contact the electrical connecting member, breaking the circuit. This self-service approach eliminates the need for external protection circuits, sensors, or control systems, thereby maintaining safety while minimizing system complexity.
2Reliability
If a PTC element is used to cut current when temperature rises, then safety against thermal runaway is improved, but the resistance increases greatly causing energy loss
Solution Approach 1:
The harmful effect of high resistance in PTC elements is extracted and eliminated from the system. Instead of relying on resistance increase to cut current, the invention uses a mechanical breaking portion that physically separates the electrical connection. This extraction of the resistance-based mechanism replaces it with a direct mechanical interruption, achieving safety without the energy loss associated with high resistance states.
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
Effectively prevents overcharge by creating a short circuit and breaking a portion of the bus bars to halt charging, enhancing safety by preventing explosions and maintaining normal operation reliability.
Implementation Method 1
an elastic member having one end supported to an inner side of the cartridge and configured to store an elastic energy by being compressed
Implementation Method 2
an expanding force applied due to a volume increase of battery cells when an overcharge situation occurs
Data Source
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AI summary
Disclosed is a battery module, which includes a cell stack having a first battery cell and a second battery cell; a first bus bar connected to the cell stack and having a first polarity; a second bus bar connected to the cell stack and having a second polarity opposite to the first polarity; a short-circuit unit configured to move toward the first bus bar and the second bus bar by receiving an expanding force caused by a volume increase of the first battery cell and the second battery cell so that the first bus bar and the second bus bar are electrically connected to generate a short circuit; and a cartridge configured to at least partially accommodate the first bus bar, the second bus bar and the short-circuit unit.