Miniature Electrochemical Cell with Ceramic Substrate Hermetic Seal
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Solution Overview
Problem
Conventional miniature electrochemical cells face challenges with inconsistent hermetic seals, corrosion, and limited energy density due to crimped metal/plastic seals, which are not suitable for small sizes and may not provide long-term reliability, especially for implanted devices.
Innovation Solution
The use of ceramic materials as insulating layers with metal-containing feedthroughs formed by co-firing metallic paste in via holes, combined with physical vapor deposition for smooth substrate surfaces and novel fill port designs, creates a hermetically sealed miniature electrochemical cell with high volumetric efficiency and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crimped metal/plastic seals are used in conventional coin cells, then the cell can be assembled with simple structure, but the hermetic seal is inconsistent and porous, compromising long-term reliability
Solution Approach 1:
The patent uses a composite seal structure consisting of a metal base, a plastic gasket, and a metal lid. The metal base and lid provide structural strength and hermetic sealing, while the plastic gasket provides electrical isolation and flexibility. This composite approach combines the advantages of different materials to achieve both simplicity and reliability in the seal structure.
Solution Approach 2:
The patent applies different materials and properties to different parts of the seal structure. The metal base and lid have high mechanical strength and hermetic properties, while the plastic gasket has electrical insulation properties and flexibility. Each component is optimized for its specific function, achieving reliable hermetic sealing without excessive complexity.
2Quantity of substance
If crimped seals are used to electrically isolate base and lid, then electrical isolation is achieved, but the seal occupies peripheral volume that reduces space for electrodes
Solution Approach 1:
The patent uses a thin plastic gasket as a flexible electrical isolation layer between the metal base and lid. This thin film provides sufficient electrical insulation while occupying minimal volume, maximizing the space available for electrodes while maintaining hermetic seal performance.
Solution Approach 2:
The patent transitions from a purely mechanical crimped seal to a multi-layer structure that utilizes different dimensions and properties. The plastic gasket provides electrical isolation in the radial dimension, while the metal base and lid provide hermetic sealing in the axial dimension, efficiently utilizing space for electrodes.
3Volume of moving object
If cell size is reduced below conventional coin cell dimensions, then smaller form factor is achieved, but crimped seals become too small to construct reliably
Solution Approach 1:
The patent changes the manufacturing parameters and materials used for the seal structure. Instead of relying on small-scale crimping operations that become unreliable at miniaturized dimensions, the patent uses a multi-layer assembled structure with optimized material properties that can be reliably manufactured at smaller scales, enabling cell volumes below conventional coin cell sizes.
4Strength
If formable material is used to seal anodized layer to base, then electrical isolation is provided, but sealing strength is insufficient to withstand pressure from evolved gas
Solution Approach 1:
The patent uses a composite seal structure where the metal base and lid provide high mechanical strength to withstand pressure from evolved gas, while the plastic gasket provides electrical isolation. This composite approach achieves both strength and electrical isolation without excessive complexity.
Solution Approach 2:
The patent applies different materials with optimized properties to different parts of the seal structure. The metal components provide mechanical strength and hermetic sealing, while the plastic gasket provides electrical isolation. Each component is optimized for its specific function, achieving both strength and electrical isolation efficiently.
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
This approach ensures a hermetic seal that lasts for 10 years or more, prevents moisture ingress and electrolyte leakage, and accommodates dimensional changes in solid-state cells, providing reliable power for small devices without compromising electrical isolation or increasing size.
Implementation Method 1
The insulating ceramic is joined to the opposite polarity terminals using a metal-containing feedthrough formed by co-firing a metallic paste in a via hole extending through a green ceramic.
Implementation Method 2
physical vapor deposition for smooth substrate surfaces
Data Source
AI summary
A miniature electrochemical cell having a volume of less than 0.5 cc is described. The cell has a casing of first and second ceramic substrates that are hermetically secured to each other to provide an internal space housing an electrode assembly. First and second conductive pathways extend through the ceramic substrates. The pathways have respective inner surfaces that are conductively connected to the respective anode and cathode current collectors and respective outer surfaces that provide for connection to a load. An electrolyte in the internal space of the housing activates the electrode assembly.