Bi-Material Battery Disconnect Bracket for Thermal Runaway Isolation
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Solution Overview
Problem
Existing battery management systems for electric vehicles struggle to effectively mitigate the propagation of thermal events within battery packs, which can lead to thermal runaway and reduce the longevity and performance of the battery cells.
Innovation Solution
A bi-material battery disconnect bracket system that rapidly isolates battery cells experiencing thermal events by using a bistable bimetallic element with different coefficients of thermal expansion, transitioning from a closed, conductive position to an open, isolation position when a temperature threshold is reached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional battery management systems are used to regulate temperature, then the system structure remains simple, but the ability to mitigate thermal event propagation is insufficient
Solution Approach 1:
The patent employs a bi-material bracket where one material has a higher coefficient of thermal expansion than the other. When temperature exceeds a threshold, the differential expansion causes the bracket to deform and transition from a closed conductive position to an open isolation position, automatically disconnecting the thermal and electrical connection of the affected battery cell. This passive thermal response mechanism significantly improves thermal event mitigation capability without adding complex active control systems.
Solution Approach 2:
The disconnect bracket is constructed from two different materials with distinct thermal expansion coefficients, creating a bi-material composite structure. This composite design enables the bracket to respond differentially to temperature changes, triggering automatic disconnection when thermal thresholds are exceeded. The use of composite materials provides an elegant solution that enhances safety functionality while maintaining relatively simple system architecture.
2Object-affected harmful factors
If battery cells are kept connected to maintain electrical continuity, then the battery pack operates efficiently, but thermal runaway can propagate to adjacent cells
Solution Approach 1:
The bi-material bracket is pre-configured in a closed conductive position during normal operation, maintaining electrical continuity and efficient battery pack operation. However, the bracket is designed with inherent thermal response characteristics that will automatically trigger disconnection when temperature thresholds are exceeded. This preliminary configuration allows the system to maintain productivity under normal conditions while being pre-prepared to mitigate thermal runaway propagation through automatic disconnection when needed.
Solution Approach 2:
The disconnect bracket operates autonomously based on thermal conditions without requiring external control systems or sensors. When the temperature of the affected battery cell exceeds the threshold, the bi-material bracket self-actuates through differential thermal expansion, automatically opening the connection to isolate the thermal runaway cell. This self-service mechanism ensures both efficient operation during normal conditions and automatic safety intervention when thermal events occur, without compromising productivity through complex control systems.
3Ease of operation
If the bracket remains in a closed conductive position, then electrical continuity is maintained, but the cell cannot be isolated during thermal events
Solution Approach 1:
The bi-material bracket leverages differential thermal expansion between two materials with different coefficients of thermal expansion. When temperature increases beyond a threshold, the material with higher expansion coefficient expands more, causing the bracket to deform and transition from its stable closed conductive position to an open isolation position. This thermal expansion mechanism provides automatic disconnection capability during thermal events while maintaining simplicity through passive physical response rather than active control systems.
Solution Approach 2:
The bracket utilizes phase transition in its operational states, switching between two stable equilibrium positions: a closed conductive state for normal operation and an open isolation state for thermal event response. The bi-material construction enables this bistable behavior where thermal energy input triggers a transition between discrete operational phases, providing automatic disconnection capability without complex mechanisms or external control systems.
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 system effectively prevents the propagation of thermal events by rapidly disconnecting overheated battery cells, thereby protecting adjacent cells and the entire battery pack from thermal runaway, while maintaining optimal battery performance.
Implementation Method 1
the first material having a larger coefficient of thermal expansion than the second material, such that an increase in temperature above a defined threshold experienced by the body causes the first material to expand more than the second material, thereby transitioning the body from a first equilibrium state representing a closed, conductive position to a second equilibrium state representing an open, isolation position
Implementation Method 2
a bracket body formed of a first material on a first major surface of the body, and a second material on an opposing second major surface of the body, the first material having a larger coefficient of thermal expansion than the second material
Data Source
AI summary
An electric vehicle battery disconnect bracket configured disconnect one or more battery cells or modules experiencing a thermal event within a battery pack to mitigate propagation of the thermal event throughout the battery pack, including a bracket body formed of a first material on a first major surface of the body, and a second material on an opposing second major surface of the body, the first material having a larger coefficient of thermal expansion than the second material, such that an increase in temperature above a defined threshold experienced by the body causes the first material to expand more than the second material, thereby transitioning the body from a first equilibrium state representing a closed, conductive position to a second equilibrium state representing an open, isolation position.