Inter-Connector Non-Uniform Thickness for Weldability and Strength

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Solution Overview

Problem

Existing inter-connectors for serially connected unit cells face challenges in achieving both strong mechanical coupling and effective electrical welding, often resulting in poor welds due to current diversion through thicker inter-connectors, especially when the inter-connector is thicker than the unit cell's outer wall.

Innovation Solution

The inter-connector design features a support frame with a welding projection thickness defined by the depression's thickness, ensuring the inter-connector is thicker than the unit cell's outer wall for mechanical strength while maintaining a thinner surrounding area to facilitate effective welding, and includes a spacer to prevent short-circuits and enhance cooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the inter-connector is made thicker to provide sufficient mechanical strength, then the mechanical strength is improved, but the weldability deteriorates because current flows through the inter-connector instead of to the unit cell outer wall

Engineering Contradiction:
Improvemechanical strengthVSAvoidweldability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The inter-connector is designed with non-uniform thickness, featuring a thinner welding portion (thinner than the unit cell outer wall) and a thicker support portion (thicker than the unit cell outer wall). This local quality variation allows the welding portion to provide good electrical contact for welding while the support portion provides sufficient mechanical strength to secure the unit cells together.

Inventive Principle:
Principle #3Local quality

2Reliability

If the inter-connector is made thinner to improve weldability, then the weldability is improved, but the mechanical strength deteriorates because it cannot securely hold the two unit cells together

Engineering Contradiction:
ImproveweldabilityVSAvoidmechanical strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The inter-connector is designed with non-uniform thickness, featuring a thinner welding portion (thinner than the unit cell outer wall) and a thicker support portion (thicker than the unit cell outer wall). This local quality variation allows the welding portion to provide good electrical contact for welding while the support portion provides sufficient mechanical strength to secure the unit cells together.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The inter-connector includes a welding projection that extends in the thickness direction, creating a multi-dimensional structure. The projection has a specific height that allows it to protrude from the inter-connector surface, providing both adequate welding surface area and maintaining the overall thin profile where needed for weldability.

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

3Strength

If expensive metal materials are used in the inter-connector to achieve sufficient strength with a thinner design, then the mechanical strength is improved, but the manufacturing cost increases

Engineering Contradiction:
Improvemechanical strengthVSAvoidmanufacturing cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The inter-connector is designed with non-uniform thickness, featuring a thinner welding portion (thinner than the unit cell outer wall) and a thicker support portion (thicker than the unit cell outer wall). This local quality variation allows the welding portion to provide good electrical contact for welding while the support portion provides sufficient mechanical strength to secure the unit cells together.

Inventive Principle:
Principle #3Local quality

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 design achieves improved weldability and mechanical strength for serially connected unit cells, preventing current diversion and ensuring secure connections while maintaining a low cost and efficient manufacturing process.

Implementation Method 1

Contact resistance welding is commonly used in coupling the inter-connector to the cells because it is useful for welding small objects.

Methodology Applied
Scientific EffectContact resistance welding: Welding

Implementation Method 2

If the inter-connector is thicker than the outer wall of the unit cell, the current from a welding electrode contacting the inter-connector flows through the inter-connector instead of to the outer wall of the unit cell.

Methodology Applied
Scientific EffectElectrical resistance heating: Joule Heating

Data Source

PatentEP1953849B1Inter-connector for connecting unit cells in series
Publication Date: 2013.06.05 SAMSUNG SDI CO LTD
  • EP1953849B1 patent drawingFigure 1
  • EP1953849B1 patent drawingFigure 2A
  • EP1953849B1 patent drawingFigure 2B~2C

AI summary

An inter-connector interposed between two serially connected unit cells provides mechanical strength and conductivity to the serial connection between the unit cells. Embodiments of the inter-connector comprise a supporting frame providing mechanical support for the two unit cells; a welding projection for welding the interconnector to a unit cell; and a welding projection surrounding area located between the welding projection and the supporting frame, wherein the supporting frame is thicker than the welding projection surrounding area, and the welding projection is thicker than the welding projection surrounding area.