Solid Electrolyte Membrane Solvent Removal via Liquid Substitution
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Solution Overview
Problem
Existing methods for producing proton-conductive solid electrolyte membranes face challenges such as residual solvent interference with proton conductivity, difficulty in removing high-boiling-point solvents, limited material usage, and inefficiencies in large-scale continuous production, leading to suboptimal membrane quality and performance in fuel cells.
Innovation Solution
A method involving the casting of a dope containing a solid electrolyte and organic solvent onto a moving support, followed by peeling and contacting with a poor solvent of lower boiling point, and subsequent drying to form a uniform and efficient solid electrolyte membrane, utilizing a mixture of solvents with controlled ratios and temperatures to ensure complete solvent removal without pore formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-boiling-point organic solvent is used in the dope solution, then the solid electrolyte can be properly dissolved and cast, but the solvent is difficult to remove completely, leading to residual solvent interference with proton conductivity
Solution Approach 1:
The drying process is segmented into multiple stages: initial drying at moderate temperature to remove most solvent, followed by high-temperature drying to remove residual solvent. This segmentation allows complete solvent removal without compromising proton conductivity.
Solution Approach 2:
The dope solution is prepared with optimal solvent composition and viscosity before casting, ensuring proper solid electrolyte dissolution and uniform membrane formation. This preliminary preparation prevents solvent entrapment and facilitates complete removal during drying.
2Reliability
If the membrane is dried at high temperature to remove solvent, then proton conductivity is improved, but micropores may form in the membrane structure
Solution Approach 1:
The drying process uses periodic temperature variation: initial moderate temperature drying to remove bulk solvent, then gradual temperature increase to high temperature for residual solvent removal. This periodic heating prevents sudden vaporization that would cause micropore formation while ensuring complete solvent removal for high proton conductivity.
3Reliability
If conventional solution casting method is used, then membrane production is achieved, but the process requires large-sized facilities including solvent recovery devices, reducing productivity
Solution Approach 1:
The invention extracts and eliminates the solvent recovery device from the conventional solution casting process. By using a solvent system that can be completely removed by simple drying without requiring complex recovery equipment, the process is simplified and productivity is increased while maintaining membrane quality.
4Ease of manufacture
If melt extrusion method is used to produce membrane, then no solvent is required, but the polymer is denatured due to heating and impurities remain in the membrane
Solution Approach 1:
The invention changes the processing parameters from high-temperature melt extrusion to low-temperature solution casting followed by controlled drying. This parameter change allows solvent removal without polymer denaturation and ensures impurity elimination, achieving high membrane purity while maintaining ease of manufacture.
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 enables the continuous production of solid electrolyte membranes with excellent proton conductivity and uniform quality, enhancing fuel cell performance by ensuring complete solvent removal and preventing micropore formation, thus overcoming previous limitations in scalability and material usage.
Implementation Method 1
drying said wet membrane to form a solid electrolyte membrane
Data Source
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AI summary
A dope (24) containing a solid electrolyte and an organic solvent is cast onto a web (111) to form a casting membrane (24a). The casting membrane (24a) is contacted with a first liquid (65a). A remaining solvent on the casting membrane (24a) is reduced. The casting membrane (24a) is peeled off as a membrane (62) from a belt (82). In a tenter device (64), the membrane (62) is dried while being stretched. Thereafter, the membrane (62) is contacted with a second liquid (66a). The membrane (62) is transported to a drying chamber (69) and dried while being supported by plural rollers (68). Since the membrane (62) is dried after substituting the first and second liquids (65a) and (66a) for the organic solvent, it becomes easy to evaporate and remove the remaining organic solvent in the membrane (62) together with the first and second liquids (65a) and (66a).