Screw-Coupled Button Cell Casing for Pressure Leak Prevention
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Solution Overview
Problem
Button-type secondary batteries face issues with internal pressure causing separation of upper and lower cans, leading to potential gas and electrolyte leakage, and have complex manufacturing processes.
Innovation Solution
A button-type secondary battery design featuring a lower can with a first screw thread, an upper can with a corresponding second screw thread, and an insulator to prevent short-circuiting, with an electrode tab extending to contact the upper can, ensuring strong coupling through screw-coupling and using polybutylene terephthalate (PBT) for the insulator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If press-fitting is used to couple upper and lower cans, then the manufacturing process is simple, but the coupling strength is insufficient and cans separate under internal pressure
Solution Approach 1:
The coupling mechanism is segmented into multiple functional elements: screw threads on the lower can, corresponding screw threads on the upper can, and an insulator with protrusions that engage with recesses. This segmentation allows each element to contribute to the overall coupling strength while maintaining manufacturing simplicity.
Solution Approach 2:
The insulator is pre-formed with protrusions that align with recesses on the can surfaces before assembly. The screw threads are pre-formed on the cans during manufacturing. These preliminary actions ensure that when components are assembled, they automatically engage in the correct configuration, achieving strong coupling without complex assembly procedures.
2Strength
If screw-coupling is used to strengthen the connection between cans, then the coupling strength increases, but the manufacturing process becomes more complex
Solution Approach 1:
The insulator serves multiple functions simultaneously: it provides electrical insulation between the upper and lower cans, mechanical coupling through protrusions engaging with recesses, and structural support. The screw threads on both cans serve dual purposes of mechanical fastening and sealing engagement. This multi-functionality reduces the need for additional components, thereby limiting the increase in device complexity.
Solution Approach 2:
The insulator is merged with the coupling mechanism by integrating protrusions directly into the insulator body. The sealing function is merged with the mechanical fastening function by having the screw threads engage both the insulator and the can surfaces. This merging of functions into unified components avoids the need for separate insulation pieces, seals, and fasteners, thus limiting complexity increase.
3Stability of the object's composition
If the cans are tightly fitted to maintain shape, then structural stability is good, but no space remains for expansion under internal pressure
Solution Approach 1:
The coupling system transitions from a static press-fit to a dynamic screw-coupled system that can accommodate pressure variations. The screw threads allow for controlled expansion and contraction of the can assembly in response to internal pressure changes, while the insulator with its protrusions and recesses provides flexible mechanical interlocking that maintains stability during normal operation but allows controlled movement under pressure.
Solution Approach 2:
The insulator acts as a cushioning element between the upper and lower cans, absorbing and distributing the stress from internal pressure before it can cause separation. The protrusions and recesses create a mechanical interlock that prevents complete separation while allowing controlled expansion. This beforehand cushioning prevents the harmful effects of pressure buildup while maintaining structural integrity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design provides strong coupling to prevent harmful gas and electrolyte leakage while simplifying the manufacturing process, enhancing production efficiency and airtightness.
Implementation Method 1
a first screw thread is formed on an outer circumferential surface of the lower can; an upper can which is configured to cover an opening of an upper end of the lower can and on which a second screw thread corresponding to the first screw thread is formed on an inner circumferential surface thereof
Implementation Method 2
an insulator interposed between the upper can and the lower can to prevent the upper can and the lower can from being short-circuited
Implementation Method 3
an electrode tab extending from an electrode of the electrode assembly is in contact with the upper can
Data Source
AI summary
A button-type secondary battery includes an electrode assembly; a lower can in which the electrode assembly is disposed and on which a first screw thread is defined on an outer circumferential surface thereof; an upper can which is configured to cover an opening of an upper end of the lower can and on which a second screw thread corresponding to the first screw thread is defined on an inner circumferential surface thereof; and an insulator interposed between the upper can and the lower can to prevent the upper can and the lower can from being electrically short-circuited with each other, wherein an electrode tab extending from an electrode of the electrode assembly is in contact with the upper can.