Screw-Coupled Button Cell Housing for Leak-Resistant Assembly
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Solution Overview
Problem
Button-type secondary batteries face issues with gas and electrolyte leakage due to excessive internal pressure and inefficient use of space within the battery, leading to potential separation of can components and reduced capacity and energy density.
Innovation Solution
A button-type secondary battery design featuring a screw-coupled structure with a polybutylene terephthalate insulator and a horizontally stacked electrode assembly, where the first electrode tab extends to contact the upper can, enhancing coupling strength and preventing leakage, while optimizing the vacuum ratio and manufacturing process for improved capacity and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If press-fitting is used to assemble upper and lower cans, then manufacturing is simple, but coupling strength is insufficient and cans separate under excessive internal pressure
Solution Approach 1:
The can assembly is segmented into upper and lower cans with distinct functions. The lower can provides structural support and sealing, while the upper can is designed to be screw-coupled to it, allowing differential pressure management. This segmentation enables each part to be optimized for its specific role in withstanding internal pressure.
Solution Approach 2:
Screw threads are pre-formed on the outer circumferential surface of the lower can and corresponding inner circumferential surface of the upper can before assembly. This preliminary preparation of threading allows for strong, reliable coupling when the cans are assembled, ensuring adequate coupling strength to prevent separation under excessive internal pressure while maintaining manufacturing efficiency.
2Strength
If cans are manufactured to match electrode assembly size for press-fitting, then coupling is achieved, but no vacuum space is available reducing battery capacity
Solution Approach 1:
The lower can is designed with a specific cylindrical shape and screw thread configuration that provides both structural integrity for coupling and creates optimal vacuum space. The local geometry of the can's inner surface and the screw thread design are optimized to maximize the volume available for the electrode assembly while maintaining adequate coupling strength.
Solution Approach 2:
The invention transitions from two-dimensional press-fitting contact to three-dimensional screw-coupled engagement. The screw threads create a multi-dimensional coupling mechanism that provides strong mechanical interlocking while allowing the cans to be manufactured with dimensions that optimize vacuum space for battery capacity without compromising coupling strength.
3Strength
If screw-coupling is used to strengthen can connection, then coupling strength improves, but device complexity increases
Solution Approach 1:
The screw threads on the lower and upper cans serve multiple functions: they provide strong mechanical coupling to prevent can separation under pressure, create a sealed connection when combined with the insulator, and enable adjustable positioning during assembly. This multi-functionality achieves strong coupling without proportionally increasing structural complexity.
Solution Approach 2:
Instead of adding complex external fastening mechanisms to achieve strong coupling, the invention inverts the approach by integrating screw threads directly into the can structures themselves. This inversion simplifies the overall device by making the coupling mechanism inherent to the can design rather than an added complexity.
4Ease of manufacture
If horizontal stacking is used for electrode assembly, then manufacturing is simplified, but space utilization must be optimized to maximize capacity
Solution Approach 1:
The electrode assembly is arranged in a horizontal stacked configuration rather than vertical winding, utilizing the horizontal dimension within the cylindrical can space. This dimensional change simplifies the manufacturing process by allowing straightforward stacking of electrode layers while the can's cylindrical geometry and screw-coupled assembly optimize the use of available volume to maintain high energy density.
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 ensures strong coupling to prevent gas and electrolyte leakage, maximizes battery capacity and energy density by eliminating wasted space, and simplifies the manufacturing process for increased production efficiency.
Implementation Method 1
a first screw thread is formed on an outer circumferential surface of the lower can... a second screw thread corresponding to the first screw thread is formed on an inner circumferential surface of the upper can
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
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. The electrode assembly is formed by horizontally stacking a plurality of first electrodes, a separator, and a second electrode. A first electrode tab extending to be connected to each of the first electrodes of the electrode assembly is in contact with the upper can.