Polymer Electrolyte Membrane for High-Temperature Fuel Cells
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Solution Overview
Problem
Fuel cells with polymer electrolyte membranes face challenges in maintaining proton conductivity at high temperatures due to moisture depletion, and existing electrodes and electrolytes suffer from mechanical instability, chemical instability, and poor phosphoric acid retention, limiting their efficiency and commercial viability.
Innovation Solution
A compound obtained by polymerizing a diisocyanate-based compound and an aromatic polyol, combined with an interpenetration polymer, is used to create fuel cell electrodes and electrolyte membranes that enhance thermal stability, reduce activation time, and improve phosphoric acid retention, enabling efficient operation at high temperatures without humidification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polymer electrolyte membranes are operated at high temperatures (at least 100°C) to enhance cell system efficiencies, then efficiency is improved, but moisture in the membrane is depleted and evaporated, reducing effectiveness
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte membrane by incorporating phosphoric acid-doped polybenzimidazole polymers, which have different thermal and moisture retention properties compared to conventional perfluorocarbon sulfonic acid membranes. This compositional parameter change enables the membrane to maintain effectiveness at high operating temperatures without requiring humidification
Solution Approach 2:
The patent creates a composite electrolyte membrane material by combining polybenzimidazole polymer with phosphoric acid dopant. This composite structure provides both high-temperature stability and proton conductivity, resolving the contradiction between operating temperature and membrane effectiveness
2Temperature
If liquid phosphoric acid is used as electrolyte in phosphoric acid fuel cells operating at 150-200°C, then high temperature operation is enabled, but the liquid phosphoric acid interferes with gas diffusion in the electrodes
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte from liquid phosphoric acid to solid-state phosphoric acid-doped polymer. This parameter change eliminates the harmful effect of liquid acid interfering with gas diffusion while maintaining the ability to operate at elevated temperatures
Solution Approach 2:
The patent replaces the liquid electrolyte system with a solid polymer electrolyte system. This substitution eliminates the mechanical interference of liquid flow with gas diffusion in electrodes, while the solid polymer matrix still allows ionic conduction
3Object-generated harmful factors
If PTFE is added to electrodes to prevent water-induced gas diffusion, then gas diffusion control is improved, but the electrode composition becomes more complex and phosphoric acid retention decreases
Solution Approach 1:
The patent extracts and removes PTFE from the electrode composition, eliminating the need for this hydrophobic additive. The gas diffusion control function is achieved instead through the phosphoric acid-doped polymer electrolyte membrane itself, which provides inherent gas barrier properties without requiring PTFE
4Ease of manufacture
If air is supplied to cathode instead of oxygen, then commercialization feasibility is improved, but activation time increases to about a week even with optimized electrode composition
Solution Approach 1:
The patent changes the electrode material composition parameters by using phosphoric acid-doped polybenzimidazole, which has superior electrochemical stability and catalytic activity compared to conventional materials. This parameter change enables rapid activation with air supply, eliminating the week-long activation period while maintaining commercialization feasibility
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 solution results in improved cell voltage performance, reduced activation time, and enhanced thermal stability, allowing fuel cells to operate effectively under non-humidified conditions with improved mechanical and chemical stability.
Implementation Method 1
a compound according to an embodiment of the present invention is a product obtained by polymerizing a composition that contains a diisocyanate-based compound represented by Formula 1 below and an aromatic polyol represented by Formula 2 below
Implementation Method 2
non-humidified electrolyte membranes that operate at temperatures of at least 100° C. without humidification have been developed. For example, polybenzimidazole doped with phosphoric acid has been disclosed as a material for a non-humidified electrolyte membrane
Implementation Method 3
the compound and an interpenetration polymer... enhance thermal stability, reduce activation time, and improve phosphoric acid retention
Data Source
AI summary
A compound that is a polymerization product of a compound composition that contains a diisocyanate-based compound and an aromatic polyol, a composition that contains the compound and an interpenetration polymer, a fuel cell electrode including either the compound or the composition, a fuel cell electrolyte membrane including either the compound or the composition, and a fuel cell including at least one selected from the group consisting of the fuel cell electrode and the fuel cell electrolyte membrane.