Lithium-Ion Button Cell Top Plate With Asymmetric Safety Vent
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Solution Overview
Problem
Rechargeable lithium-ion button cells face challenges in maximizing energy density due to inefficient use of internal space, inadequate safety vent designs, and welding process complications, particularly in small form factors like wireless earphones and hearing aids.
Innovation Solution
A single-sided battery design with a novel top plate structure featuring an outer-rivet configuration and asymmetric safety vent, combined with a protection ring to shield electrodes from welding heat, and variable-width electrodes to optimize space utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a three-layer sidewall structure (inner cup, insulation gasket, outer cup) is used, then insulation and structural integrity are improved, but internal space is reduced
Solution Approach 1:
The patent divides the traditional three-layer sidewall structure into separate functional components: the insulation gasket is segmented into multiple insulation layers integrated with the top plate, while the cup structure is simplified to a single layer. This segmentation allows each component to perform its specific function more efficiently without requiring all three layers to coexist as separate structural elements.
Solution Approach 2:
The patent merges the insulation gasket function directly into the top plate structure through integrated insulation layers, eliminating the need for a separate outer cup. The top plate and insulation gasket are combined into a unified structure that provides both structural support and electrical insulation, thereby reducing the number of discrete components and freeing up internal space.
2Volume of moving object
If a single-layer sidewall structure with laser welding is used, then internal space is increased, but insulation between terminals and safety become problematic
Solution Approach 1:
The patent applies local quality by providing insulation only where electrically isolated regions are needed, rather than using a complete outer cup. The insulation layers are strategically positioned on the top plate to insulate specific terminal areas, allowing laser welding in non-critical zones while maintaining electrical isolation where required.
Solution Approach 2:
The patent employs asymmetric insulation design where the insulation layers are distributed unevenly across the top plate based on electrical isolation requirements. The first insulation layer covers the first terminal area while the second insulation layer covers the second terminal area, creating an asymmetric pattern that optimizes both space utilization and safety.
3Reliability
If aluminum rivet is used for cathode terminal, then oxidation resistance is improved, but sealing strength is reduced due to small size
Solution Approach 1:
The patent uses composite material construction for the rivet assembly, combining aluminum (for oxidation resistance at the cathode terminal) with other materials in the insulation and sealing structures. The rivet itself remains aluminum for chemical stability, while the integrated insulation layers and top plate structure provide the additional mechanical strength needed for reliable sealing in small button cell formats.
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
Enhances energy density, improves safety by ensuring reliable gas release, and simplifies the welding process, reducing battery failure rates while maintaining safety standards.
Implementation Method 1
laser welded with a top plate on the opening end of the housing cup sidewall
Data Source
AI summary
A rechargeable lithium-ion button cell battery having a sealed housing includes a top flat plate and a round or oval cup sealed by laser at the rim of top plate whereas connecting the opening end of the cup sidewall. The top plate has a centered sandwiched structure including two outer plates at upper and lower position, that clamping one inner pin-like conductive plate by its flange, insulated by a gasket. The upper plate of the outer plates has an asymmetric shape to its center line, which allows asymmetric sealing force applied on the inner pin-like plate flange to act as a safety vent. Inside the sealed housing the anode and cathode electrodes are either spiral wound or stacked with separator to be a round or oval roll, one electrode is connected to the cup, the other electrode is connected to the inner pin-like conductive plate of the top plate.