Secondary Battery Cap Assembly With Anti-Crack Insulator Protrusions
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Solution Overview
Problem
The cap assembly of secondary batteries often fails to properly seal the case due to loose assembly or cracking during the manufacturing process, leading to reduced reliability and stability.
Innovation Solution
A cap assembly design featuring a vent and cap down coupled by an insulator with protrusions that enhance binding strength and prevent cracking, utilizing a rotatable vent and movable protrusions to improve assembly integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the cap assembly components are assembled without additional binding structures, then the assembly process is simple, but the binding strength between components is insufficient leading to loose assembly or cracking
Solution Approach 1:
The insulator is segmented with multiple protrusions (4 to 16 protrusions) distributed around its circumference. Each protrusion acts as an independent binding element that engages with corresponding features on the vent and cap down, distributing the binding stress across multiple contact points rather than a single continuous structure.
Solution Approach 2:
The protrusions have non-uniform thickness distribution, with thicker regions (0.07 mm or more) at critical binding locations and thinner regions elsewhere. This local variation in material distribution optimizes the binding strength at specific interfaces while minimizing overall material usage and maintaining flexibility where needed.
2Ease of manufacture
If the vent is made rotatable with respect to the cap down, then the assembly tolerance is improved, but the stability of the cap assembly is reduced due to potential loosening
Solution Approach 1:
The vent is designed to be rotatable relative to the cap down during assembly, allowing dynamic adjustment to achieve proper alignment. The protrusions on the insulator maintain continuous contact during this rotation, guiding the components into their final stable position while accommodating manufacturing tolerances.
Solution Approach 2:
The protrusions are designed with sufficient thickness (0.07 mm or more) and strategic positioning to prevent cracking before it can occur during assembly or operation. This preemptive design approach compensates for the potential instability introduced by the rotatable joint, ensuring that the binding strength is sufficient to prevent loosening under normal operating conditions.
Data Source
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AI summary
A cap assembly includes a cap down, a vent above the cap down, and an insulator between the cap down and the vent, the insulator including one or more protrusions protruding toward the vent. A secondary battery includes a case accommodating an electrode assembly, and a cap assembly coupled to an opening of the case, wherein the cap assembly includes a cap down, a vent above the cap down, and an insulator between the cap down and the vent, the insulator including one or more protrusions protruding toward the vent.