Secondary Battery Laser Sealing With Stepped Joint Geometry

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Solution Overview

Problem

The existing laser sealing apparatus can cause laser penetration into the battery when a clearance between the case main body and the sealing plate is larger than the position of laser light application, potentially damaging the electrode assembly.

Innovation Solution

A method of manufacturing a secondary battery that involves positioning the case main body and sealing plate with a level difference and applying laser light at an inclination angle to prevent laser penetration, using a specific range of level difference, clearance, and inclination angle to ensure secure joining without damaging the electrode assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If laser light is applied to join the case main body and sealing plate, then joining strength is improved, but laser penetration may occur damaging the electrode assembly

Engineering Contradiction:

Improvejoining strengthVSAvoidlaser penetration damage

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a level difference in the vertical dimension between the edge portion and outer end surface, creating a stepped structure that blocks the laser path. This dimensional change prevents laser penetration into the battery interior while maintaining effective laser joining at the interface, thus resolving the contradiction between achieving strong joining and preventing harmful laser penetration.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The outer end surface of the sealing plate acts as an intermediary element that intercepts and blocks the laser beam before it can penetrate into the battery. This intermediary structure absorbs or reflects the laser energy, protecting the electrode assembly while allowing the joining process to proceed effectively.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If clearance between case main body and sealing plate is increased, then assembly tolerance is improved, but laser penetration risk increases

Engineering Contradiction:

Improveassembly toleranceVSAvoidlaser penetration risk

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

By creating a level difference (stepped structure) in the vertical dimension, the patent effectively blocks the laser path even when horizontal clearance exists between the case main body and sealing plate. This allows assembly tolerance to be relaxed without increasing laser penetration risk, as the stepped structure prevents laser access to the interior regardless of horizontal misalignment.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The level difference structure serves as a pre-designed protective feature that anticipates and prevents laser penetration before it can occur. By positioning the outer end surface at a lower level than the edge portion, the patent creates a built-in barrier that cushions against the harmful effect of laser penetration, even when clearance is present.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Object-affected harmful factors

If level difference between edge portion and outer end surface is increased, then laser penetration is suppressed, but joining effectiveness may be reduced

Engineering Contradiction:

Improvelaser penetration suppressionVSAvoidjoining effectiveness

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent optimizes the level difference parameter within a specific range (0.3-1.4mm) to balance two opposing requirements: suppressing laser penetration while maintaining joining effectiveness. This parameter optimization ensures that the outer end surface is sufficiently low to block laser penetration, yet not so low as to prevent effective laser heating and joining at the interface between the case main body and sealing plate.

Inventive Principle:

Principle #35Parameter changes

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 effectively suppresses laser penetration, preventing damage to the electrode assembly and ensuring a robust joining process, while allowing for increased inner space utilization and improved battery performance.

Implementation Method 1

joining portions of the case main body and the sealing plate by applying the laser light to the edge portion and the outer end surface

Methodology Applied

Scientific EffectLaser: Laser

Implementation Method 2

applying the laser light... with the result that the electrode assembly in the battery may be damaged

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS20250337063A1Method of manufacturing secondary battery and secondary battery

Publication Date: 2025.10.30 PRIME PLANET ENERGY & SOLUTIONS INC

AI summary

A method of manufacturing a secondary battery includes: positioning a case main body and a sealing plate so as to provide a level difference between an edge portion of the case main body and an outer end surface of the sealing plate in a first direction; and when the level difference is defined as H1, a maximum clearance between an opening and the outer end surface in a second direction orthogonal to the first direction is defined as L, and an inclination angle of an optical axis of laser light with respect to the first direction is defined as θ, joining portions of the case main body and the sealing plate by applying the laser light to the edge portion and the outer end surface with the optical axis being inclined at an angle equal to or more than a numerical value of θ that satisfies a relation of tan θ=L/H1.