Battery Cell Butt Weld Seam for Electrode Tab Connection

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Solution Overview

Problem

Lithium-ion traction batteries face challenges in utilizing installation space efficiently while maintaining mechanical and electrical stability in the connection between electrode lugs and conductors, often requiring high energy for welding and resulting in stress on the battery cell structure.

Innovation Solution

The battery cell employs a butt weld seam for connecting electrode lugs to conductors, eliminating overlapping areas and allowing for improved space utilization, with options for laser beam or electron beam welding, and potentially other methods like MIG or plasma welding, to ensure reliable and efficient connections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If overlapping areas are used for welded connection between electrode lugs and collectors, then mechanical stability is improved, but installation space utilization deteriorates

Engineering Contradiction:

Improvemechanical stabilityVSAvoidinstallation space

Core Design Contradiction:

StrengthVSVolume of moving object

Solution Approach 1:

Instead of using the conventional overlapping joint (lap joint) where the collector overlaps the electrode lug, the patent inverts the connection approach by using a butt joint where the collector end connects directly to the electrode lug end face. This inversion eliminates the overlapping area while maintaining connection strength through proper welding on the end surface.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If ultrasonic welding with very high energy is used to connect electrode lugs to conductors, then reliable electrical connection is improved, but stress on battery cell structure deteriorates

Engineering Contradiction:

Improveelectrical connectionVSAvoidbattery cell structure

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent changes the welding parameters by transitioning from ultrasonic welding (which requires very high energy) to laser beam welding or electron beam welding. These alternative welding methods achieve reliable electrical connections with different energy delivery characteristics that reduce stress on the battery cell structure while maintaining connection reliability.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If very high energy is used for welding, then safe and reliable connections are improved, but energy consumption deteriorates

Engineering Contradiction:

Improvewelded connectionVSAvoidwelding energy

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent replaces the mechanical ultrasonic welding system with laser beam welding or electron beam welding. These technologies use concentrated energy beams (optical or electromagnetic) instead of mechanical vibration, achieving reliable welded connections with potentially lower overall energy consumption and reduced process complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If overlapping areas are used for connection, then electrical connection stability is improved, but space for active material is reduced

Engineering Contradiction:

Improveelectrical connectionVSAvoidactive material

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent inverts the conventional connection geometry from overlapping to butt joint configuration. This allows the collector to connect to the electrode lug end face without requiring overlapping area, thereby freeing up space that can be utilized for additional active material in the battery cell.

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

This approach enhances space utilization, reduces stress peaks, and maintains mechanical stability, enabling either increased capacity or reduced dimensions of the battery cell while ensuring a reliable electrical connection.

Implementation Method 1

The electrode lugs are connected to the conductor on the face side by a butt weld seam, in particular by means of laser beam welding or electron beam welding

Methodology Applied

Scientific EffectLaser beam welding: Laser Beam Welding

Implementation Method 2

The electrode lugs are connected to the conductor on the face side by a butt weld seam, in particular by means of laser beam welding or electron beam welding

Methodology Applied

Scientific EffectElectron beam welding: Electron Beam

Implementation Method 3

The electrode lugs are each connected to the conductor on the face side by a butt weld seam by means of friction stir welding

Methodology Applied

Scientific EffectFriction stir welding: Friction Welding

Data Source

PatentEP3618147B1Battery cell and method for manufacturing the same

Publication Date: 2022.11.09 VOLKSWAGEN AG

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AI summary

The invention relates to a battery cell 1 with a stack 2 of positive and negative electrodes 8a, 8b and separators 7 arranged between them, wherein the electrodes 8 each have electrode tabs 3 which are each welded to at least one positive and at least one negative conductor 4. The electrode tabs 3 are connected to the conductor 4 at their end faces by a butt weld 5. The battery cell according to the invention allows for better utilization or reduction of the cell's installation space while maintaining the same capacity.