Battery Insulation Film Diffusion Structure for Laser Weld Protection
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Solution Overview
Problem
Conventional power storage device manufacturing methods face issues with laser passing during welding, where laser light enters the case main body, potentially melting the insulation film and causing scorching or internal short-circuiting of the electrode body due to machining errors creating a gap between the case and sealing plate.
Innovation Solution
A manufacturing method that includes a film body with a light diffusion part on its bent parts to diffuse laser light, reducing beam density and preventing the film from melting and the electrode body from being damaged during laser welding, by providing a surface roughened light diffusion part on the film body that faces the sealing plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser welding is performed to join the sealing plate to the case main body, then the sealing performance is improved, but laser light may pass through the gap and damage the electrode body
Solution Approach 1:
The patent introduces a film body as an intermediary component positioned between the laser path and the electrode body. This film body absorbs or blocks the laser light that passes through the gap, preventing it from reaching and damaging the electrode body, thus resolving the contradiction between achieving good sealing through laser welding and preventing laser-induced damage to internal components
Solution Approach 2:
The patent utilizes the harmful laser light that passes through the gap and converts it into a beneficial effect by having the film body absorb the laser energy. The absorbed laser energy is converted into heat that melts the film body to form a protective slag layer, which then protects the electrode body from direct laser exposure, thus converting the harmful laser passing into a protective mechanism
2Object-affected harmful factors
If a film body is placed between the case main body and electrode body to prevent metal foreign substances, then the electrode body protection is improved, but the film body may melt due to laser passing
Solution Approach 1:
The patent modifies the physical and chemical parameters of the film body by selecting specific material compositions and controlling thickness parameters. These parameter changes enable the film body to withstand the laser exposure conditions while maintaining its protective function, balancing the need to block metal foreign substances with the risk of laser-induced melting
3Object-affected harmful factors
If the space between case main body and sealing plate is reduced to prevent laser passing, then the laser damage is prevented, but machining precision requirements increase
Solution Approach 1:
The patent introduces the film body as a compensatory intermediary element that absorbs the variability in machining precision. Rather than requiring extremely tight gap control, the film body is designed to accommodate reasonable variations in gap size while still providing effective protection against laser passing, thus reducing the stringency of manufacturing precision requirements
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
Effectively suppresses the melting of the film body and scorching or short-circuiting of the electrode body by diffusing laser light, ensuring the power storage device's integrity and preventing heat conduction to the electrode body, even with machining errors causing laser passing.
Implementation Method 1
a light diffusion part that diffuses laser light is provided to at least the bent part
Data Source
AI summary
The present disclosure provides a manufacturing method for a power storage device including a case main body, a sealing plate, an electrode body, and a film body with an insulating property. The film body includes a long side surface, and a bent part extending from the long side surface toward the sealing plate and bent so as to get close to the electrode body. A light diffusion part that diffuses laser light is provided to the bent part. This manufacturing method includes a preparing step of preparing the film body, an accommodating step of accommodating the electrode body and the film body in the case main body, and a laser welding step of welding an outer peripheral part of the sealing plate to an inner peripheral part of an opening of the case main body by laser.