Battery Bus Bar Heat Transfer Structure to Limit Thermal Runaway
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Solution Overview
Problem
Batteries for electric vehicles experience high temperature build-up in bus bars due to electrical resistance, leading to thermal runaway events that can destroy neighboring cells, and existing solutions fail to effectively prevent this.
Innovation Solution
An electric energy storage apparatus with a heat transfer device that includes a layered structure with electrically insulating and thermally conductive materials, featuring separation regions to reduce heat transfer between battery cells, using materials like silicone and metal layers to maintain optimal temperatures and prevent thermal runaway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metallic bus bars are used to provide electrical connections between battery cells, then electrical conductivity is improved, but temperature build-up and heat propagation occur due to electrical resistance
Solution Approach 1:
The patent introduces a heat transfer device as an intermediary component between the metallic bus bar and the battery cell terminals. This device includes a first section thermally connected to the bus bar and a second section thermally connected to the battery terminal, with a phase change material positioned between these sections. The heat transfer device acts as a mediator that conducts heat away from the bus bar while the phase change material absorbs excess heat through phase transition, thereby reducing temperature build-up on the bus bar while maintaining electrical connection reliability.
Solution Approach 2:
The patent utilizes phase change material that undergoes a parameter change (phase transition) at a specific temperature. When the bus bar temperature rises, the phase change material absorbs heat by transitioning from solid to liquid phase, effectively controlling the temperature parameter. This parameter change mechanism allows the system to maintain the bus bar temperature below critical thresholds while preserving electrical conductivity.
2Use of energy by moving object
If direct thermal connection between battery cells via bus bars is maintained, then heat transfer efficiency is improved, but thermal runaway propagation occurs during thermal runaway events
Solution Approach 1:
The heat transfer device with phase change material serves as a thermal intermediary that can control heat flow direction and magnitude. During normal operation, it maintains efficient thermal connection. During thermal runaway events, the phase change material absorbs excessive heat, creating a thermal barrier that prevents runaway propagation to adjacent cells while maintaining overall heat management efficiency.
Solution Approach 2:
The patent converts the potentially harmful effect of thermal runaway by using the phase change material to absorb excess heat energy. The harmful thermal runaway heat is transformed into a beneficial phase transition process that protects adjacent battery cells, effectively converting a harmful thermal event into a protective mechanism.
3Reliability
If electrical insulation between cell connector and wall member is provided, then electrical safety is improved, but thermal conduction is reduced
Solution Approach 1:
The heat transfer device is constructed as a composite structure combining different materials with complementary properties. The first section uses a thermally conductive material to connect to the bus bar, the second section uses a thermally conductive material to connect to the battery terminal, and the intermediate layer uses phase change material. This composite structure simultaneously achieves electrical insulation (through the phase change material layer) and effective thermal conduction (through the thermally conductive sections), resolving the contradiction between electrical safety and heat dissipation capability.
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 solution effectively prevents temperature build-up on bus bars and reduces heat propagation between cells, enhancing the service life of the battery by maintaining optimal temperatures and preventing thermal runaway.
Implementation Method 1
a heat transfer device, electrically insulating and thermally conductively connecting (e.g. only) the cell connector and the wall member
Implementation Method 2
a (e.g. phase change) heat transfer device
Data Source
Figure 1A~1D
Figure 2A~2F
Figure 3A~4
AI summary
The invention relates to an electrical energy storage apparatus (10) for a vehicle. The apparatus (10) comprises a first battery cell (11a); a second battery cell (11b); a cell connector (12), electrically conductively connecting the first and second battery cell (11a, 11b); a wall member (13) arranged at the first and second battery cell (11a, 11b); and a heat transfer device (14), electrically insulating and thermally conductively connecting the cell connector (12) and the wall member (13). The heat transfer device (14) has a first transfer section (14a), connecting a first portion (12a) of the cell connector (12) to the wall member (13), and a second transfer section (14b), connecting a second portion (12b) of the cell connector (12) to the wall member (13). Thereby, the first and second transfer section (14a, 14b) are at least partially separated from each other by a separation region (15), having a reduced thermal conductivity compared to the first and second transfer section (14a, 14b), to reduce a heat transfer between the first and second battery cell (11a, 11b) via the heat transfer device (14).