Sealed Battery Shield Geometry for Laser Weld Insulator Protection
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Solution Overview
Problem
High-energy-density batteries face issues with insulator degradation and reduced airtightness during laser welding due to the close proximity of the laser-welded region and insulating member, where variations in component sizes or workpiece positioning can cause direct laser application to the shield, leading to searing and reduced insulating capacity.
Innovation Solution
A sealed battery design featuring a shield with an inclined portion on the closing plate's outer surface, positioned between the insulator and the fitted portion, which redirects laser light away from the insulator, preventing direct exposure and subsequent degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a rectangular cross-section shield is used between the insulator and fitted portion, then the shield structure is simple and easy to manufacture, but laser light can be directly applied to the shield and leak to the insulator, causing insulator degradation
Solution Approach 1:
The shield cross-section is changed from a rectangular shape to a shape with curved surfaces. The first and second curved surfaces replace the sharp corners of the rectangular cross-section, creating a smooth, rounded profile. This curvature prevents laser light from directly striking the shield and leaking to the insulator, while maintaining manufacturing feasibility through standard forming processes.
Solution Approach 2:
The shield cross-section employs asymmetric curvature where the first curved surface has a different radius of curvature than the second curved surface. This asymmetric design optimizes laser light redirection on each side while maintaining structural integrity and manufacturing simplicity, resolving the contradiction between ease of manufacture and protection reliability.
2Quantity of substance
If the distance between the collector terminal and fitted portion is reduced to achieve high energy density, then the battery energy density increases, but the laser-welded region and insulator are located closer, causing laser light to more easily leak to the insulator
Solution Approach 1:
The shield with curved cross-section serves as an intermediary element positioned between the laser-welded region and the insulator. This intermediary structure actively redirects laser light away from the insulator through its curved surfaces, preventing direct exposure and degradation while enabling the reduced spacing necessary for high energy density.
Solution Approach 2:
The shield's curved surfaces convert the potentially harmful direct laser exposure into a beneficial redirection of laser light away from the insulator. The curvature causes laser light to reflect at angles that prevent it from reaching the insulator, transforming what would be a harmful effect into a protective mechanism that enables closer component spacing.
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 design effectively prevents insulator degradation and maintains the airtightness of the battery by ensuring the laser light is applied to the inclined portion of the shield rather than the insulator, even when the laser beam deviates slightly during welding.
Implementation Method 1
the shield includes an inclined portion inclined toward the fitted portion, the inclined portion defining a side face of the shield adjacent to the fitted portion. If laser light applied during laser welding is somewhat deviated toward the insulator, this embodiment would cause the laser light to be applied to the vicinity of the root of the inclined portion.
Data Source
AI summary
A sealed battery includes: a battery case including an opening; a closing plate closing the opening; a collector terminal including an external connector exposed at an outer surface of the closing plate; a resin insulator insulating the closing plate and the external connector from each other; a laser-welded region formed on a fitted portion between the battery case and the closing plate; and a shield disposed on the outer surface of the closing plate. The shield is interposed between the insulator and the fitted portion. The shield includes an inclined portion inclined toward the fitted portion. The inclined portion defines a side face of the shield adjacent to the fitted portion.