Glass-Ceramic Seal for Electrochemical Cell Thermal Stress
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sealing technologies for high-temperature electrochemical cells, such as EVHTs and SOFCs, face challenges in maintaining integrity and preventing gas leaks due to differential thermal expansions and material corrosion, with prior solutions like metal seals, nickel or silver solders, and glass-ceramic joints either failing to provide reliable electrical insulation or being difficult to manufacture and dismantle.
Innovation Solution
A method involving the use of a glass or glass-ceramic gasket with a solid ceramic core, where beads of glass or glass-ceramic are deposited and solidified ex situ, allowing for controlled thickness and reduced mechanical stress during assembly, with a flow limiter to prevent material dissemination, and compression applied above the glass transition temperature to accommodate thermal expansions without damaging the cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glass-ceramic joints are used to accommodate thermal expansion differences, then the seal can resist pressure differences, but the joint becomes rigid and may damage the cell during cooling if thermal expansion coefficients do not match
Solution Approach 1:
The patent applies a two-stage thermal processing approach: first heating above the glass transition temperature to maintain flexibility and accommodate thermal expansion differences, then controlled cooling to allow the glass-ceramic to crystallize and become rigid for pressure resistance. This dynamic temperature control resolves the contradiction between needing rigidity for pressure resistance and flexibility to avoid thermal stress damage.
Solution Approach 2:
The patent changes the thermal parameters (temperature and heating rate) during the sealing process. By heating above the glass transition temperature initially, the glass-ceramic remains flexible to accommodate differential thermal expansion. The controlled cooling process then allows crystallization to occur, transforming the material from flexible to rigid state, thereby achieving both thermal compatibility and pressure resistance.
2Ease of manufacture
If slips are used to deposit glass material, then the joint can be manufactured, but the slips deform under compression and create uncontrolled thickness and gas bubbles
Solution Approach 1:
The patent changes the physical state parameter of the glass material from paste/slurry form to powdered form. The powdered glass is mixed with binder to create a deformable paste that can be deposited, then heated to evaporate the binder and sinter the glass particles. This parameter change allows controlled deposition while avoiding the deformation and bubble issues associated with traditional slips, achieving both ease of manufacture and thickness precision.
Solution Approach 2:
The patent replaces the mechanical compression process with a thermal processing process. Instead of mechanically compressing the glass material to achieve bonding, the patent uses heating to evaporate the binder and sinter the glass particles, creating a strong bond without the need for high mechanical compression that would deform the material and create bubbles.
3Ease of repair
If metal seals are used to facilitate dismantling, then the seal can be removed and reused, but the rigidity remains high and electrical conduction occurs between interconnectors
Solution Approach 1:
The patent uses a composite material system consisting of glass-ceramic (providing sealing and insulation), ceramic core (providing structural support and insulation), and metal interconnectors (providing mechanical strength and electrical conduction). This composite approach allows the seal itself to be electrically insulating while the overall assembly remains mechanically strong and可拆卸. The glass-ceramic composite provides both the sealing function and electrical insulation, resolving the contradiction between metal seal rigidity and insulation.
4Ease of manufacture
If nickel or silver solders are used to join components, then the joint can be formed, but the materials are expensive, chemically incompatible, and difficult to dismantle and recycle
Solution Approach 1:
The patent employs a glass-ceramic sealing material that is inexpensive, chemically inert, and compatible with all surrounding materials. The sealing process creates a permanent bond that eliminates the need for complex dismantling and recycling procedures. The glass-ceramic material itself serves as both the seal and the bonding agent, replacing expensive and problematic soldering materials with a simple, reliable, and environmentally friendly alternative.
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 reliable electrical insulation, controlled sealing, and reduced mechanical stress on the cell, facilitating the assembly and operation of electrochemical cell stacks while maintaining the integrity of the seal and preventing gas leaks.
Implementation Method 1
heating the core and the cords to produce an evaporation of binders present in the cords and solidify said cords
Implementation Method 2
the absence of crystallization gives them a certain flexibility above the glass transition temperature which makes it possible to better accommodate differential thermal expansions
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
A solid seal, in particular used in electrochemical cells, comprises a continuous and solid ceramic core (1) comprising two opposing faces on which glass or vitroceramic beads (22, 23) are deposited. This seal is heated to a physically free state in order to evaporate the binders initially present in the bead paste. This makes it possible to effectively control the shape of the bead, the quantity of glass deposited and the final thickness of same, and assists degassing. The solid seal obtained is then inserted into the assembly comprising the electrochemical cell, which can then be clamped by exerting compressive stress on said seal, which relieves the cell and prevents risks of rupture.