Secondary Battery Case Sidewall Thickness for Crack-Free Crimping
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Solution Overview
Problem
Existing secondary battery designs face challenges in maintaining structural integrity during the formation of bead and crimp portions, leading to potential cracking due to abrupt changes in thickness of the sidewall, which affects the rigidity and manufacturing process efficiency.
Innovation Solution
The sidewall of the secondary battery case is designed with distinct cylindrical portions of varying thicknesses, where the second cylindrical portion has a thickness greater than the first and less than the third, optimized to minimize abrupt thickness changes and enhance rigidity, thereby preventing cracks during the formation of bead and crimp portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the sidewall thickness is increased to enhance rigidity, then structural strength is improved, but weight and material usage increase
Solution Approach 1:
The sidewall is designed with non-uniform thickness distribution, featuring a first cylindrical portion with greater thickness for enhanced rigidity, a second cylindrical portion with reduced thickness for weight savings, and a third cylindrical portion with increased thickness for structural support. This local variation in thickness allows the structure to have high rigidity where needed while minimizing weight overall.
Solution Approach 2:
The sidewall is divided into three distinct cylindrical portions with different thickness characteristics. The first cylindrical portion has a thickness of 0.15 mm or greater, the second cylindrical portion has an average thickness of 0.165 mm or more, and the third cylindrical portion has a thickness of 0.25 mm or greater. This segmentation allows each portion to be optimized for its specific functional requirements.
2Reliability
If the sidewall thickness is uniformly increased to prevent cracking during bead and crimp formation, then structural integrity is improved, but manufacturing complexity and material usage increase
Solution Approach 1:
Different portions of the sidewall are assigned different thickness levels based on their specific functional requirements. The first cylindrical portion (thickness ≥ 0.15 mm) and third cylindrical portion (thickness ≥ 0.25 mm) provide structural support and crack resistance, while the second cylindrical portion (average thickness ≥ 0.165 mm) is optimized for its specific function. This localized optimization prevents cracking without requiring uniform thickness increase throughout the entire sidewall.
Solution Approach 2:
The thickness parameter of the sidewall is varied across different cylindrical portions rather than maintaining a uniform value. By changing the thickness parameter locally (0.15-0.25 mm range), the design achieves crack prevention during bead and crimp formation while avoiding the complexity and material waste associated with uniform thickness increase.
3Stability of the object's composition
If the second cylindrical portion thickness is increased to match the third cylindrical portion, then structural uniformity is improved, but weight and space efficiency deteriorate
Solution Approach 1:
The second cylindrical portion is deliberately designed with a thickness (average ≥ 0.165 mm) that is less than the third cylindrical portion (thickness ≥ 0.25 mm) but greater than or equal to the first cylindrical portion (thickness ≥ 0.15 mm). This local differentiation in thickness allows the battery to achieve optimal weight efficiency while maintaining structural stability through the graduated thickness progression across the three portions.
Data Source
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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.