Shape-Memory Bus Bar for Battery Module Overheat Current Cutoff
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Solution Overview
Problem
Lithium secondary batteries used in battery modules and packs face safety risks due to potential overheating and explosion, particularly in large devices like electric vehicles, where conventional safety measures like PTC devices and fuses require separate mounting spaces and may not effectively block current flow when temperature rises.
Innovation Solution
A battery module design featuring a bus bar with linear grooves on its surfaces, where electrode leads are inserted and physically compressed, using shape memory alloy plates that expand in thickness at a predetermined temperature, releasing physical contact and blocking electrical connections between battery cells, thereby preventing current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional safety measures like PTC devices and fuses are used, then safety protection is provided, but additional mounting space is required and current flow may not be effectively blocked when temperature rises
Solution Approach 1:
The safety function is merged into the bus bar structure itself by incorporating shape memory alloy plates with temperature-responsive grooves. The bus bar simultaneously serves as an electrical conductor and a safety device that automatically releases electrode leads when temperature exceeds the predetermined threshold, eliminating the need for separate PTC devices or fuses.
Solution Approach 2:
The bus bar with shape memory alloy plates performs self-protection by automatically releasing the electrode leads when the temperature rises above the predetermined level. The shape memory effect enables the bus bar to autonomously respond to temperature changes and block current flow without requiring external control systems or additional safety components.
2Reliability
If shape memory alloy plates are used in the bus bar, then automatic current blocking is achieved at predetermined temperature, but the bus bar structure becomes more complex
Solution Approach 1:
The shape memory alloy plates change their physical properties (groove dimensions) in response to temperature parameter changes. When the temperature reaches the predetermined threshold, the alloy undergoes a phase transformation that causes the grooves to expand, automatically releasing the electrode leads and blocking current flow without requiring complex control mechanisms.
Solution Approach 2:
The bus bar is constructed as a composite structure combining conventional conductive material with shape memory alloy plates. This composite design integrates the electrical conductivity function with the temperature-responsive safety function, achieving automatic current blocking while maintaining structural integrity and electrical performance.
3Reliability
If electrode leads are physically compressed in grooves for electrical connection, then reliable electrical contact is achieved, but safety is compromised when temperature rises
Solution Approach 1:
The shape memory alloy grooves are pre-designed with specific dimensional characteristics that provide strong electrical contact at normal temperatures. The grooves are configured to physically compress the electrode leads, ensuring reliable electrical connection while embedded with shape memory alloy plates that will expand at predetermined temperature to release the leads and prevent overheating.
Solution Approach 2:
The electrical connection mechanism transitions from a static compressed state to a dynamic release state based on temperature conditions. At normal temperatures, the grooves maintain physical compression for reliable electrical contact. When temperature rises above the predetermined threshold, the shape memory alloy plates expand, dynamically changing the groove dimensions to release the electrode leads and block current flow.
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 solution ensures safety by automatically blocking current flow when the battery module overheats, enhancing safety without the need for additional space or changes to the battery cells' manufacturing process, and can be integrated with existing protection circuits for dual safety assurance.
Implementation Method 1
using shape memory alloy plates that expand in thickness at a predetermined temperature, releasing physical contact and blocking electrical connections between battery cells
Data Source
AI summary
A battery module blocks current when the temperature rises, a battery pack includes the battery module, and a vehicle includes the battery pack. The battery module includes a bus bar having an approximately thin plate shape compared to a length and a width and having linear grooves provided in a left surface and a right surface along a longitudinal direction, respectively; and battery cells respectively located on the left surface and the right surface of the bus bar, physically contacting with their respective electrode leads inserted into the grooves, and electrically connected to each other with the bus bar interposed therebetween, and wherein sizes of the grooves increase in a thickness direction at a certain temperature or higher to release a physical contact between the electrode leads and the bus bar such that an electrical connection between the battery cells is released.