Battery Pack Busbar With Melt-Link Thermal Runaway Isolation
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Solution Overview
Problem
High-capacity battery packs used in electric vehicles and electric bicycles are prone to thermal runaway and explosions due to decomposition reactions under abnormal conditions, which can lead to fires and accidents by propagating thermal runaway between connected battery modules.
Innovation Solution
Incorporation of busbars with linking portions made of materials with lower melting points than the connection portions to quickly disconnect electrical connections during thermal runaway, using materials like aluminum for the linking portions and copper for the connection portions, and positioning these linking portions to face weak points in the battery cell casing to facilitate rapid disconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-capacity battery modules are connected in series or parallel to meet power requirements, then power and capacity increase, but thermal runaway can propagate between modules causing fires
Solution Approach 1:
A cut-off unit is introduced as an intermediary component between battery modules. This unit includes a busbar with a low-melting-point linking portion that acts as a thermal fuse, automatically disconnecting electrical connections when thermal runaway occurs in one module, thereby preventing propagation to other modules while maintaining normal operation during regular use
2Reliability
If conventional busbars with uniform high-melting-point materials are used, then electrical connection reliability is maintained, but thermal runaway propagates between modules
Solution Approach 1:
The busbar is designed with non-uniform material properties: the linking portion uses a low-melting-point material (e.g., aluminum or alloy) while the connection portions use high-melting-point materials (e.g., copper). This local quality differentiation enables the linking portion to melt and disconnect under thermal stress, preventing thermal runaway propagation while maintaining reliable electrical connections during normal operation
3Quantity of substance
If battery modules are closely arranged to maximize energy density, then space utilization improves, but thermal runaway spreads faster between modules
Solution Approach 1:
The cut-off unit with low-melting-point linking portion serves as a thermal and electrical barrier between closely arranged battery modules. During normal operation, it maintains electrical connectivity for high energy density. When thermal runaway occurs, the linking portion melts due to its low melting point, creating both thermal and electrical isolation that slows down thermal runaway propagation between modules
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
Prevents the propagation of thermal runaway and explosions from affecting neighboring battery modules and the entire battery pack by rapidly cutting off electrical connections, enhancing safety and reliability.
Implementation Method 1
the first linking portion includes a material having a melting point lower than that of the first connection portion or the second connection portion
Data Source
AI summary
A battery module includes a case, a plurality of battery cells accommodated in the case, and a first busbar connecting at least one of the plurality of battery cells to a conductive connector, wherein the first busbar includes a first connection portion connected to the at least one battery cell, a second connection portion connected to the conductive connector, and a first linking portion connecting the first connection portion and the second connection portion to each other, wherein the first linking portion includes a material having a melting point lower than that of the first connection portion or the second connection portion.