Secondary Battery Joining Mark with Inner Chamfered Corners

Solution Overview

Problem

Secondary batteries used as vehicle driving power sources face issues with separator damage and generation of coarse foreign matter during ultrasonic joining due to increased stress and vibration, which can lead to short circuits and reduced battery performance.

Innovation Solution

The design includes a secondary battery configuration with a chamfered corner shape on the inner side of the electrode body's joining mark, reducing stress on the separator and preventing coarse foreign matter generation by optimizing the ultrasonic joining process, specifically using a horn with a tip shape that corresponds to the chamfered corners during the joining process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the distance between the foil collecting portion and the active material layer is reduced to increase the size of the active material layer, then the energy density is improved, but the separator is likely to be damaged during ultrasonic joining due to stress and vibration

Engineering Contradiction:

Improvevolume of active material layerVSAvoidseparator damage

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The horn tip is designed with localized chamfered corners at specific positions (inner side of the electrode body) rather than a uniform shape. This local differentiation allows the horn to apply ultrasonic vibration in a way that avoids concentrating stress on the separator while still achieving effective joining of the foil collecting portion to the current collector terminal.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The horn tip shape is made asymmetric by providing chamfered corners only at specific locations (inner side corners) while leaving other corners (outer side corners) without chamfering. This asymmetric design creates a non-uniform vibration pattern that protects the separator from damage while maintaining effective joining performance.

Inventive Principle:

Principle #4Asymmetry

2Ease of manufacture

If ultrasonic joining is performed with a conventional horn shape, then the joining process is simple, but coarse foreign matter is generated due to anvil cutting the current collector terminal surface

Engineering Contradiction:

Improvejoining process simplicityVSAvoidcoarse foreign matter generation

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The horn tip is designed with localized chamfered corners at specific positions (inner side of the electrode body) rather than a uniform shape. This local differentiation allows the horn to apply ultrasonic vibration in a way that avoids concentrating stress on the separator while still achieving effective joining of the foil collecting portion to the current collector terminal.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The horn tip shape is made asymmetric by providing chamfered corners only at specific locations (inner side corners) while leaving other corners (outer side corners) without chamfering. This asymmetric design creates a non-uniform vibration pattern that protects the separator from damage while maintaining effective joining performance.

Inventive Principle:

Principle #4Asymmetry

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 configuration effectively prevents separator damage and suppresses the generation of coarse foreign matter during manufacturing, enhancing the reliability and performance of secondary batteries, particularly those with thicker electrode bodies used in vehicle driving applications.

Implementation Method 1

vibrating the horn while pressing the horn against the foil collecting portion toward the anvil

Methodology Applied

Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Data Source

PatentUS11563216B2Secondary battery and manufacturing method of secondary battery

Publication Date: 2023.01.24 TOYOTA JIDOSHA KK

AI summary

A secondary battery includes an electrode body, a battery case, and an electrode terminal. The electrode body has a foil collecting portion. The electrode terminal corresponding to at least one of a positive electrode and a negative electrode is electrically connected to the foil collecting portion via a current collector terminal. The current collector terminal is joined to the foil collecting portion. The foil collecting portion has a joining mark composed of a plurality of recesses on a surface on an opposite side of the foil collecting portion from a surface joined to the current collector terminal. The joining mark has two corners on an inner side of the electrode body and two corners on an outer side of the electrode body, and only the two corners on the inner side of the electrode body have a chamfered shape.