Sealed Battery Laser Joining with Parallel Branched Beams

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Solution Overview

Problem

Existing laser processing methods for sealed type batteries fail to achieve a sufficient joining strength between the battery outer case and the current collector tab without causing penetration, leading to potential short circuits and detachment issues during drops or impacts.

Innovation Solution

A laser processing method that branches a laser beam into multiple parallel beams, forming line-shaped melting portions along the surface of the battery outer case, ensuring these melting portions connect with the current collector tab without penetrating it, thereby enhancing the joining strength and preventing spatter mixtures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If high output laser beam is used to form melting portion, then joining strength is improved, but penetration of current collector tab occurs causing short circuit

Engineering Contradiction:

Improvejoining strengthVSAvoidshort circuit prevention

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The laser beam is divided into multiple branched laser beams (first branched laser beam and second branched laser beam) that irradiate different regions of the battery outer case. This segmentation allows the total laser power to be distributed across multiple zones, creating a melting portion with sufficient width for strong joining while controlling the depth to prevent penetration through the current collector tab, thus resolving the contradiction between joining strength and short circuit prevention.

Inventive Principle:

Principle #1Segmentation

2Reliability

If condensed light spot diameter is narrowed to prevent penetration, then short circuit is prevented, but joining width is reduced lowering joining strength

Engineering Contradiction:

Improveshort circuit preventionVSAvoidjoining strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

Multiple branched laser beams are combined to irradiate adjacent regions of the battery outer case simultaneously. The individual melting portions created by each branched laser beam merge to form a continuous, wide melting portion that provides sufficient joining width for high joining strength while each individual beam maintains a condensed spot diameter that prevents penetration through the current collector tab.

Inventive Principle:

Principle #5Merging (Combining)

3Strength

If line welding with multiple lines is performed to improve joining strength, then device complexity increases

Engineering Contradiction:

Improvejoining strengthVSAvoidwelding process complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The mechanical approach of performing multiple separate line welds is replaced by an optical system that branches a single laser beam into multiple parallel beams. This substitution allows multiple welding zones to be processed simultaneously in one operation, achieving high joining strength through a wide melting portion while avoiding the complexity of coordinating multiple separate welding operations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method effectively improves the joining strength between the battery outer case and the current collector tab, preventing short circuits and maintaining the battery's integrity during drops or impacts by forming connected melting portions without penetrating the current collector tab, thus enhancing the battery's reliability.

Implementation Method 1

a laser beam is branched into a first branched laser beam and a second branched laser beam... the first plate-shaped member is irradiated with the first branched laser beam and the second branched laser beam

Methodology Applied

Scientific EffectLaser irradiation: Laser

Implementation Method 2

line-shaped melting portions are formed along a surface of the first plate-shaped member by relatively moving the first branched laser beam and the second branched laser beam

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS12179285B2Laser processing method and laser processing device and sealed type battery

Publication Date: 2024.12.31 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

Provided is a laser processing method including overlapping a plurality of plate-shaped members that include a first plate-shaped member disposed on one end side of an overlapping direction and a second plate-shaped member disposed on the other end side of the overlapping direction; branching a laser beam into a first branched laser beam and a second branched laser beam; irradiating the first plate-shaped member with the first branched laser beam and the second branched laser beam in a state where the first branched laser beam and the second branched laser beam are emitted in parallel; forming line-shaped melting portions on the first plate-shaped member by moving the branched laser beams in a direction intersecting a direction in which the branched laser beams are aligned; and joining overlapped plate-shaped members in a state where the melting portion formed by using the first branched laser beam and the melting portion formed by using the second branched laser beam are connected to each other in the second plate-shaped member and the melting portions do not penetrate the second plate-shaped member.