Battery Pack Bus Bar Weld Paths for Stronger Terminal Joints

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Solution Overview

Problem

Existing battery cell connections during laser welding face challenges in maximizing coupling force while preventing base material penetration due to energy concentration at specific points.

Innovation Solution

A battery pack design with a bus bar system featuring welding portions that include laser welding lines extending in directions opposite to the overall extension, incorporating overlap avoidance regions to prevent material penetration and enhance coupling force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If laser welding line is formed over a wide area to maximize coupling force, then coupling force between bus bar and terminal is improved, but base material penetration occurs due to energy concentration at specific points

Engineering Contradiction:
Improvecoupling forceVSAvoidbase material penetration
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The welding line is designed with varying local characteristics - wider spacing between welding points in certain regions and concentrated welding points in other regions. This local variation in welding line configuration allows energy to be distributed appropriately across different areas, maximizing coupling force where needed while preventing energy concentration that would cause base material penetration in other areas.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The welding line is configured to extend in multiple directions (first direction and second direction perpendicular to each other) rather than a single linear path. This multi-dimensional arrangement distributes the laser energy across a broader area, reducing energy concentration at any single point while maintaining wide-area coverage for maximum coupling force.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If welding line proceeds in opposite direction to welding portion extension, then overlap avoidance region is created to prevent penetration, but welding path complexity increases

Engineering Contradiction:
Improvebase material penetrationVSAvoidwelding path complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Instead of continuing the welding line in the same direction as the welding portion extension, the welding line is intentionally configured to proceed in the opposite direction in specific regions. This inversion creates overlap avoidance regions that prevent base material penetration by ensuring welding points do not coincide, while the overall welding path remains systematically organized rather than randomly complex.

Inventive Principle:
Principle #13The other way round (Inversion)

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 design maximizes coupling force and prevents base material penetration, ensuring robust electrical connections and reducing the risk of damage during laser welding.

Implementation Method 1

the components may be coupled to each other through laser welding

Methodology Applied
Scientific EffectLaser welding: Laser Beam Welding

Data Source

PatentEP4307456B1Battery pack and vehicle including the same
Publication Date: 2026.02.11 LG ENERGY SOLUTION LTD
  • EP4307456B1 patent drawingFigure 1
  • EP4307456B1 patent drawingFigure 2
  • EP4307456B1 patent drawingFigure 3

AI summary

A battery pack according to an embodiment of the present disclosure includes a plurality of battery cells; a housing accommodating the plurality of battery cells; a plurality of bus bars electrically connecting the plurality of battery cells; and a first welding portion for coupling a first electrode terminal provided in each of the plurality of battery cells to the bus bar and a second welding portion for coupling a second electrode terminal provided in each of the plurality of battery cells to the bus bar, wherein at least one of the first welding portion and the second welding portion includes a region in which a laser welding line formed on the bus bar proceeds in a direction opposite to an extension direction of the welding portion.