Secondary Battery Case Sidewall Thickness for Crack-Free Molding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing secondary battery cases face issues with cracking during the molding process due to abrupt changes in thickness, which affect rigidity and structural integrity.
Innovation Solution
The secondary battery case design incorporates a sidewall with varying thicknesses in its cylindrical portions, specifically a first, second, and third cylindrical portion, where the second portion's thickness is optimized to be between 110% to 120% of the first portion's thickness, and the third portion's thickness is greater, ensuring gradual transitions to withstand molding loads without cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the sidewall has uniform thickness, then the manufacturing process is simple, but cracking occurs during molding due to stress concentration
Solution Approach 1:
The sidewall is designed with non-uniform thickness distribution, where the first cylindrical portion has a first thickness, the second cylindrical portion has a second thickness greater than the first, and the third cylindrical portion has a third thickness greater than the second. This local variation in thickness distributes stress more evenly during the molding process, preventing crack formation while maintaining structural integrity.
2Strength
If the second cylindrical portion thickness is increased to prevent cracking, then structural integrity improves, but weight increases
Solution Approach 1:
Instead of uniformly increasing the thickness of the entire sidewall, the invention selectively increases thickness only in the second cylindrical portion where it is most needed for structural support during molding. The first and third portions maintain relatively thinner sections, optimizing the weight-strength ratio by placing material only where structurally necessary.
3Ease of manufacture
If the third cylindrical portion has greater thickness for bead formation, then processability during molding improves, but material consumption increases
Solution Approach 1:
The third cylindrical portion is designed with a third thickness that is greater than the first thickness to provide sufficient material for forming the bead portion during molding. However, it is specifically noted that the third thickness is less than the second thickness, optimizing material usage by providing only the necessary thickness for the specific function of bead formation without excessive material consumption.
Data Source
AI summary
A secondary battery includes an electrode assembly including a first electrode and a second electrode, a case accommodating the electrode assembly, the case including a bottom electrically connected to the second electrode, a sidewall connected to the bottom, and a top opening opposite the bottom, and a cap assembly coupled to one end of the sidewall of the case. The sidewall of the case includes a first cylindrical portion extending from the bottom, a second cylindrical portion extending from the first cylindrical portion, and a third cylindrical portion extending from the second cylindrical portion, the first to third cylindrical portions having different thicknesses, and the electrode assembly being accommodated in the first cylindrical portion and the second cylindrical portion.