Battery Pack Bus Bar Alignment via Bent Tabs

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Solution Overview

Problem

In battery packs where unit cells are stacked, variations in thickness can lead to misalignment of electrode tabs and bus bars, resulting in insufficient bonding and potential electrical conductivity issues.

Innovation Solution

A battery pack design featuring a cell group with bent electrode tabs and a flat plate-shaped bus bar, where spacers support the electrode tabs to ensure proper alignment and contact with the bus bar, and a manufacturing method involving laser welding to secure the bus bar to the electrode tabs, ensuring consistent electrical connection despite thickness variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If unit cells are stacked with variations in thickness, then the battery pack can accommodate manufacturing tolerances, but the electrode tabs misalign with the bus bar recessed portions resulting in insufficient bonding

Engineering Contradiction:

Improvetolerance to thickness variationVSAvoidelectrical conductivity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The bus bar is pre-formed with protruding portions that extend toward the electrode tabs before assembly. These protruding portions are positioned to make contact with the electrode tabs even when there are thickness variations in the unit cells, ensuring reliable electrical connection without requiring precise alignment of recessed portions with the electrode tabs.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If recessed portions are formed in the bus bar to sandwich each electrode tab, then electrical connection is established, but the structure becomes complex and alignment sensitivity increases

Engineering Contradiction:

Improveelectrical connectionVSAvoidbus bar structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Instead of forming recessed portions in the bus bar to sandwich the electrode tabs, the invention inverts the approach by forming protruding portions on the bus bar that extend toward the electrode tabs. This simplifies the bus bar structure and reduces alignment sensitivity, as the protruding portions naturally contact the electrode tabs without requiring precise matching of recessed portions.

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of manufacture

If electrode tabs are independently inserted into recessed portions, then each tab is bonded to the bus bar, but misalignment occurs when unit cell thicknesses vary

Engineering Contradiction:

Improveindependent bondingVSAvoidalignment accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

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 solution ensures reliable electrical conductivity and improved bonding between electrode tabs and bus bars, maintaining desired electrical characteristics regardless of unit cell thickness variations, while simplifying the manufacturing process and reducing costs.

Implementation Method 1

Each of the distal end portions of the electrode tabs of at least two of the unit cells and a surface of the bus bar that faces the unit cells are in contact and welded to each other

Methodology Applied

Scientific EffectLaser welding: Laser Beam Welding

Data Source

PatentEP3367468B1Assembled battery and assembled battery manufacturing method

Publication Date: 2020.04.22 ENVISION AESC JAPAN LTD

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AI summary

[PROBLEM] To provide a battery pack in which sufficient conduction can be obtained between a bus bar and the electrode tab of each unit cell. [SOLUTION] The battery pack 100 comprises a cell group 100G and a bus bar 131. The cell group is obtained by stacking, in the thickness direction, a plurality of the unit cells 110 provided with a cell body 110H, which includes a power generation element 111 and which is formed into a flat shape, and an electrode tab 113 protrude out from the cell body, and the distal end portions 113d of the electrode tabs are bent in the stacking direction Z of the unit cells. The bus bar is formed in a flat plate shape and bonded to the distal end portions of the electrode tabs of the unit cells while facing the distal end portions, and electrically connects the electrode tabs of at least two of the unit cells with each other.