Insulated Battery Lead Structure to Prevent Welding Voids
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Solution Overview
Problem
A void often forms between the exterior body of a battery and the electrically insulating resin film of a lead with an electrically insulating resin film, leading to weakened adhesion during thermal welding.
Innovation Solution
The lead features a plate-shaped conductor with tapered conductor portions at its ends and electrically insulating resin films on both surfaces, arranged to prevent gaps and enhance adhesion by allowing the exterior body resin to fill tapered resin portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrically insulating resin films are bonded to both surfaces of the conductor, then electrical insulation is improved, but voids form between the exterior body and the resin film during thermal welding
Solution Approach 1:
The patent applies asymmetry by configuring the resin film with different thickness regions: a first thickness in the overlapping region (where margin portions of first and second resin films overlap) and a second thickness elsewhere, where the first thickness is greater than the second thickness. This asymmetric thickness distribution prevents void formation during thermal welding while maintaining electrical insulation, as the thicker overlapping region provides sufficient material for the exterior body to bond to without forming voids.
Solution Approach 2:
The patent applies local quality by making the resin film thickness position-dependent: the overlapping region has a greater thickness than other regions. This localized thickness enhancement is specifically applied where the margin portions overlap, providing targeted void prevention at the critical bonding interface between the exterior body and resin film, while maintaining thinner regions elsewhere to reduce overall material usage.
2Reliability
If the resin film covers the entire conductor surface, then electrical insulation is improved, but the exterior body cannot be thermally welded to the conductor
Solution Approach 1:
The patent applies segmentation by dividing the resin film coverage into distinct regions: the resin film covers the conductor surface for electrical insulation but intentionally leaves the end surfaces of the conductor exposed. This segmentation allows the body portion to be insulated while the end surfaces remain accessible for thermal welding of the exterior body to the conductor, resolving the contradiction between insulation and weldability.
Data Source
AI summary
A lead includes a conductor and an electrically insulating resin film. The conductor includes tapered conductor portions, each having a thickness decreasing with increasing distance from a first center that is a center of the conductor. The electrically insulating resin film has tapered resin portions each having a thickness decreasing with increasing distance from the first center. The tapered conductor portions have first conductor ends close to the first center. The tapered resin portions have first resin ends closer to the first center and second resin ends farther from the first center. Each of the first resin ends is at the same position of a corresponding one of the first conductor ends or is closer to the first center than the corresponding one is. Each of the second resin ends is farther from the first center than a corresponding end of the conductor is.