Battery Cell Tab-to-Busbar Layout for Compact Laser Welding
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Solution Overview
Problem
Existing battery cell-to-busbar connections in traction battery packs face challenges such as difficulty in proper alignment and welding complexities, leading to excessive packaging space and weld-through issues.
Innovation Solution
The implementation of tab terminal and busbar shape variations, including angled surfaces and flared portions, with laser welding and backing plates to secure the connections, reduces packaging space by positioning weld surfaces between battery cells and busbars.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional battery cell-to-busbar connections are used, then alignment and welding can be performed with conventional methods, but excessive packaging space is required and weld-through issues occur
Solution Approach 1:
The tab terminal is pre-bent to a specific angle (e.g., 45 degrees) before assembly, and the busbar is pre-positioned with spacing from the cell housing. This preliminary configuration ensures that when the tab is welded to the busbar, the weld surface is automatically positioned in the optimal location (between the cell and busbar) without requiring complex real-time alignment during welding, thus reducing packaging space while maintaining manufacturing feasibility
Solution Approach 2:
The patent changes the geometric parameters of the tab terminal (bending it at specific angles) and the busbar (positioning it at specific distances from the housing) to optimize the weld surface location. By adjusting these parameters, the weld is positioned in the space between the cell and busbar, which reduces the required packaging volume while avoiding weld-through issues that would occur with conventional flat-tab configurations
2Volume of moving object
If tab terminal is bent to optimize weld position, then packaging space is reduced, but welding complexity increases
Solution Approach 1:
The tab terminal is pre-bent to a specific angle (e.g., 45 degrees) before assembly, and the busbar is pre-positioned with spacing from the cell housing. This preliminary configuration ensures that when the tab is welded to the busbar, the weld surface is automatically positioned in the optimal location (between the cell and busbar) without requiring complex real-time alignment during welding, thus reducing packaging space while maintaining welding simplicity
Solution Approach 2:
The bent tab terminal acts as an intermediary element that bridges the cell housing and the busbar in a optimized geometric configuration. The bend angle serves as a mediator that positions the weld surface in the ideal location, simplifying the welding process by providing a predetermined optimal welding position rather than requiring complex adjustment mechanisms
3Reliability
If conventional welding positions are used, then welding process is simple, but weld-through issues occur reducing connection reliability
Solution Approach 1:
The patent changes the geometric parameters of the tab terminal (bending it at specific angles) and the busbar (positioning it at specific distances from the housing) to optimize the weld surface location. By adjusting these parameters, the weld is positioned in the space between the cell and busbar, which reduces the required packaging volume while avoiding weld-through issues that would occur with conventional flat-tab configurations
Solution Approach 2:
Instead of welding on a flat surface parallel to the cell housing, the tab terminal is bent to create a weld surface that extends in a different dimensional orientation (at an angle relative to the housing). This dimensional change positions the weld in the depth dimension between the cell and busbar, improving reliability by avoiding weld-through while the viewing windows provide optical access for welding verification
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 configuration optimizes electrical connections by minimizing packaging space and reducing weld spatter, enhancing the efficiency and reliability of battery cell-to-busbar connections.
Implementation Method 1
a weld that secures the bent tab end section to the busbar. In a further non-limiting embodiment of the foregoing traction battery pack, the weld is a laser weld.
Data Source
AI summary
Battery cell tab terminal-to-busbar configurations are provided for electrically connecting battery cells within a traction battery pack. The tab terminals may be secured to the busbar within a space that extends between the battery cells and the busbar in order to reduce the amount of packaging space required for electrically connecting the battery cells and thus reduce the overall tab terminal-to-busbar footprint. In one implementation, the tab terminals are secured to a flat surface of the busbar and are forced into contact with the flat surface by a backing plate. In other implementations, the tab terminals are secured to angled portions of the busbar.