Secondary Battery Tab Welding Non-Welding Section

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Solution Overview

Problem

Secondary batteries face insulation defects due to metal particle dispersion during the welding process between electrode tabs and lead parts, leading to potential instability and safety issues like ignition and explosion.

Innovation Solution

A method involving tack welding, cutting of unwelded tab ends, and main welding with a non-welding section between the electrode tab and lead part, using a welding guide member to prevent metal particle dispersion and maintain electrical connection, thereby reducing insulation defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If resistance welding is performed to connect electrode tabs and lead parts, then electrical connection is achieved, but metal particles disperse and cause insulation defects

Engineering Contradiction:
Improveelectrical connectionVSAvoidmetal particle dispersion
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a non-welding section as an intermediary zone between the welding part and the lead film. This non-welding section acts as a buffer that prevents metal particles generated during welding from reaching and damaging the lead film, thereby eliminating insulation defects while maintaining electrical connection through the welding part.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent divides the overlapping region between the electrode tab and lead part into distinct segments: a welding part where connection is formed and a non-welding section where no welding occurs. This segmentation allows the welding process to be localized away from the lead film, preventing particle contamination while maintaining electrical connectivity.

Inventive Principle:
Principle #1Segmentation

2Strength

If welding is performed across the entire overlapping region, then strong electrical connection is achieved, but insulation defects increase due to particle contamination

Engineering Contradiction:
Improvewelding strengthVSAvoidinsulation performance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The overlapping region is segmented into a welding part for strong electrical connection and a non-welding section for insulation protection. This segmentation ensures that welding strength is concentrated where needed while preventing insulation defects by excluding the welding process from the area adjacent to the lead film.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the electrode tab are assigned different functions: the welding part is optimized for electrical connection with full welding coverage, while the non-welding section is optimized for insulation protection by excluding welding. This local differentiation resolves the contradiction between connection strength and insulation reliability.

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

The method significantly reduces insulation defect rates and ensures stable battery performance by preventing metal particle dispersion and maintaining a consistent distance between welding parts, enhancing safety and durability.

Implementation Method 1

a welding part is formed in a partial section of an overlapping region between the electrode tab and the lead part

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

US2001/070477 A1 discloses a secondary battery where the tabs are joint to the leads by ultrasonic welding

Methodology Applied
Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Data Source

PatentEP3029758B1Method for welding electrode tab of secondary battery
Publication Date: 2021.03.17 LG ENERGY SOLUTION LTD
  • EP3029758B1 patent drawingFigure 1~2
  • EP3029758B1 patent drawingFigure 3~5
  • EP3029758B1 patent drawingFigure 6~7

AI summary

Disclosed herein are a method for welding electrode taps of a secondary battery which improves insulation defects generated during welding between the electrode taps and lead parts and an electrode assembly manufactured thereby. The method for welding electrode taps includes performing main welding to connect electrode taps protruded from electrode plates provided in a battery and lead parts electrically connecting the electrode taps to external terminals and having a lead film on the surfaces thereof and, in main welding, a welding part is formed in a partial section of an overlapping region between the electrode tap and the lead part, and a non-welding section is formed between the welding part and the lead film.