Bus Bar Hole Welding for Stable Battery Tab Connections
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Solution Overview
Problem
Existing laser welding methods for connecting electrode tabs to bus bars in battery modules, particularly when using heterogeneous materials like aluminum and copper, result in unstable welding quality with high tensile strength deviations and increased resistance, leading to manufacturing complexity and cost, as well as reduced durability.
Innovation Solution
A battery module design with a bus bar having holes for electrode tab insertion, where the welding bead's dimensions and composition are controlled to ensure stable welding between heterogeneous materials, specifically aluminum and copper, by using a welding bead that satisfies specific geometric and compositional criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If laser welding is used to connect electrode tabs to bus bars, then energy density requirements are met, but tensile strength shows large deviation and welding defects occur
Solution Approach 1:
The patent changes the welding parameters by controlling the laser welding process to achieve specific welding bead dimensions (width W and height H satisfying 0.05mm ≤ W ≤ 0.15mm and 0.03mm ≤ H ≤ 0.08mm). This parameter control resolves the contradiction by maintaining consistent welding quality while meeting energy density requirements.
Solution Approach 2:
The patent applies preliminary action by pre-positioning the electrode tabs on the bus bar surface before welding, ensuring proper alignment and contact. This preliminary preparation reduces welding defects and tensile strength deviation during the actual welding process.
2Ease of manufacture
If electrode tabs of multiple specifications are bent and cut for welding, then connection is achieved, but process complexity and manufacturing costs increase
Solution Approach 1:
The patent extracts the complex bending and cutting processes from the manufacturing flow. Instead of modifying electrode tabs of multiple specifications through bending and cutting, the invention uses a standardized tab insertion method into bus bar holes, eliminating the need for complex shape modifications and reducing process complexity.
Solution Approach 2:
The patent segments the connection process into separate steps: electrode tab preparation, insertion into bus bar holes, and welding. This segmentation allows each step to be optimized independently, reducing overall process complexity while maintaining connection quality.
3Adaptability or versatility
If existing laser welding methods are used for heterogeneous materials, then welding is achieved, but stable welding quality (tensile strength, electrical resistance) cannot be secured
Solution Approach 1:
The patent applies parameter changes by optimizing laser welding parameters (power, speed, focus position) specifically for heterogeneous material combinations. This enables stable welding quality across different material pairs while maintaining adaptability to various material specifications.
Solution Approach 2:
The patent introduces an intermediary approach by controlling the welding bead dimensions to act as a buffer between heterogeneous materials. The standardized bead size (W and H parameters) mediates the thermal and mechanical stresses between different materials, ensuring consistent welding quality.
4Adaptability or versatility
If electrode tab lengths vary for different cell specifications, then cell requirements are met, but resistance becomes non-uniform affecting durability
Solution Approach 1:
The patent changes the approach from varying tab lengths to controlling welding bead parameters. By maintaining consistent welding bead dimensions (W and H) regardless of tab length variations, the invention ensures uniform electrical resistance and contact quality, improving long-term durability while preserving cell specification flexibility.
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 approach achieves a welding strength more than twice that of conventional methods, with improved tensile strength and reduced contact resistance, ensuring consistent and reliable electrical connections.
Implementation Method 1
laser welding is being used as the most common bonding method
Data Source
AI summary
The present disclosure relates to a battery module comprising: a plurality of battery cells each including an electrode tab; and a bus bar connected to the electrode tab to electrically connect the plurality of battery cells to each other. The bus bar includes a plate having a plurality of holes. The electrode tab of each of the battery cells is inserted into at least a part of the plurality of holes of the plate. The electrode tab inserted into the hole and the plate are coupled to each other by a welding bead, and the welding bead has a width and a height defined by Equations 1 and 2, respectively.