Secondary Battery Laminate Case Curvature Design
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Solution Overview
Problem
Secondary batteries face challenges in maintaining structural integrity and preventing cracks due to elongation during the formation of the laminate exterior case, which affects damp-proofing and outer appearance quality.
Innovation Solution
The laminate exterior case is designed with long and short side curve portions and corner curve portions, where the curvature radii and thicknesses are specifically adjusted to reduce elongation, with curvature radii of the long side curve portions being larger than those of the short side curve portions, and corner curve portions having smaller thicknesses, thereby minimizing cracks and improving damp-proofing and appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the laminate exterior case is formed with uniform thickness, then manufacturing is simple, but cracks occur due to elongation during formation
Solution Approach 1:
The patent applies local quality by varying the thickness of different portions of the exterior case. Specifically, the corner curve portions have a first thickness, the long side curve portions have a second thickness greater than the first, and the short side curve portions have a third thickness greater than the first. This non-uniform thickness distribution compensates for elongation during formation, preventing cracks while maintaining manufacturing feasibility.
2Ease of manufacture
If the curvature radii of all curve portions are made equal, then manufacturing is easier, but elongation and cracks occur
Solution Approach 1:
The patent applies asymmetry by setting different curvature radii for different portions of the exterior case. The corner curve portions have a first curvature radius, the long side curve portions have a second curvature radius greater than the first, and the short side curve portions have a third curvature radius greater than the first. This asymmetric design distributes elongation evenly during formation, preventing concentration of stress that would cause cracks.
3Ease of manufacture
If corner curve portions have the same thickness as long and short side curve portions, then manufacturing is simpler, but cracks occur at corners due to higher stress
Solution Approach 1:
The patent applies beforehand cushioning by designing the corner curve portions with a greater thickness compared to the long and short side curve portions. This increased thickness at the corner portions, which are subjected to higher stress during formation, provides additional strength and prevents cracks before they can occur. The cushioning effect is built into the structure during manufacturing.
Data Source
AI summary
A secondary battery includes an electrode assembly, and a laminate exterior case accommodating the electrode assembly, the laminate exterior case including a pair of long side curve portions spaced apart from each other, a pair of short side curve portions spaced apart from each other, curvature radii of the long side curve portions being larger than those of the short side curve portions, and corner curve portions between respective long side curve portions and short side curve portions.