Battery Pack Module Segmentation for Short Circuit Delay
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Solution Overview
Problem
Battery packs with multiple unit cells are prone to rapid temperature increases due to external short circuits caused by conductive foreign matter, leading to potential safety hazards, especially when mounted on moving objects like vehicles.
Innovation Solution
The battery pack design includes unit cells electrically connected by busbars, with intentional spacing to delay the occurrence of external short circuits, allowing internal short circuits to break the negative electrode before an external short circuit occurs, thereby increasing contact resistance and suppressing temperature rises.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If unit cells are arranged adjacent to each other to reduce battery pack size, then the battery pack volume is reduced, but the risk of external short circuit and rapid temperature increase due to conductive foreign matter penetration is enhanced
Solution Approach 1:
The battery pack is divided into multiple battery modules, each containing a plurality of unit cells. This segmentation allows the unit cells to be arranged adjacently within each module to reduce overall volume, while the module structure provides isolation barriers that prevent conductive foreign matter from causing external short circuits between adjacent unit cells across different modules.
2Use of energy by moving object
If unit cells are arranged adjacent to each other to improve energy density, then the battery performance is enhanced, but the temperature increase rate due to Joule heating from short circuit current is accelerated
Solution Approach 1:
By segmenting the battery pack into multiple modules with unit cells arranged adjacently within each module, the design achieves high energy density while the module boundaries act as protective barriers. These barriers prevent conductive foreign matter from creating external short circuits between adjacent unit cells, thereby preventing rapid temperature increases from Joule heating even when unit cells are closely packed.
Solution Approach 2:
The battery module structure serves as an intermediary barrier between adjacent unit cells. When conductive foreign matter penetrates unit cells, the module structure prevents direct external short circuits between adjacent unit cells, mediating the potential harmful interaction and preventing rapid temperature increases while maintaining high energy density through adjacent arrangement.
3Reliability
If unit cells are disposed apart from each other to prevent external short circuits, then the safety is improved, but the battery pack volume increases
Solution Approach 1:
The battery pack is segmented into multiple modules, allowing unit cells to be arranged adjacently within each module to minimize volume. The module segmentation itself provides the necessary safety isolation, eliminating the need for additional spacing between all unit cells while maintaining protective barriers against external short circuits.
4Power
If unit cells are electrically connected by busbars to enable current flow, then the power output is enhanced, but the contact resistance decreases allowing higher short circuit current flow
Solution Approach 1:
The electrical connection system is segmented into module-level connections using busbars, which enable efficient current flow and high power output within each module. The module structure itself acts as a protective barrier that limits the propagation of short circuit currents between modules, thereby controlling the overall short circuit current even though busbars provide low-resistance connections for normal operation.
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 design effectively suppresses rapid temperature increases and external short circuits by delaying the conductive foreign matter's path through the battery pack, ensuring the negative electrode is broken before an external short circuit can form, thus enhancing safety and performance.
Implementation Method 1
a short circuit current may be generated in the unit cells 110A to 110C, and there is a possibility that the temperature of the unit cells 110A to 110C may rapidly increase due to Joule heating by the short circuit current
Data Source
AI summary
A battery pack includes a plurality of unit cells, each including an electrode body having a structure in which a positive electrode and a negative electrode are stacked, and a busbar that electrically connects a positive electrode terminal to a negative electrode terminal between the unit cells. The unit cells are stacked adjacent to one another in the same direction as a direction in which the positive electrode and the negative electrode of the electrode body are stacked. The busbar electrically connects the unit cells disposed apart from each other among the unit cells excluding the unit cells disposed adjacent to each other.