Boron Phosphate Matrix Layer for Fuel Cells
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Solution Overview
Problem
Phosphoric acid fuel cells face performance degradation due to reactions between the electrolyte and matrix materials, and previous matrix layers like silicon carbide suffer from oxide dissolution, leading to acid loss and blockages.
Innovation Solution
A porous matrix layer comprising at least 90% boron phosphate is used between the electrodes, with phosphoric acid as the electrolyte, providing chemical stability and preventing reactant mixing, while allowing for a thin layer to minimize IR losses and enhance fuel cell efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If phenolic resin matrix layer is used, then the matrix provides structural support, but the organic material reacts with phosphoric acid at elevated temperatures producing catalyst-poisoning molecules
Solution Approach 1:
The patent changes the chemical composition parameter of the matrix layer from organic phenolic resin to inorganic boron phosphate, which does not react with phosphoric acid to produce harmful substances, thereby eliminating catalyst poisoning while maintaining structural support
Solution Approach 2:
The patent uses a composite structure combining boron phosphate particles with a binder material, creating a composite matrix layer that provides both structural integrity and chemical stability against phosphoric acid
2Stability of the object's composition
If silicon carbide matrix layer is used, then the matrix provides chemical stability, but the oxide on silicon carbide dissolves slowly during operation converting to insoluble silicon phosphate
Solution Approach 1:
The patent changes the matrix material from silicon carbide to boron phosphate, which has superior chemical stability and does not undergo dissolution or conversion reactions with phosphoric acid, thereby preventing electrolyte loss
Solution Approach 2:
The patent selects boron phosphate as a more stable material that prevents the short-term dissolution issues experienced with silicon carbide, effectively creating a long-lasting matrix layer
3Strength
If silicon carbide matrix layer is used, then the matrix provides structural integrity, but insoluble silicon phosphate blocks fuel or oxidant gas delivery to electrodes
Solution Approach 1:
The patent changes the matrix material composition to boron phosphate, which does not form insoluble phosphate deposits, thereby preventing blockage of gas delivery channels while maintaining structural integrity
4Reliability
If thicker matrix layer is used, then electrolyte retention is improved, but IR losses increase reducing fuel cell efficiency
Solution Approach 1:
The patent uses a porous structure of boron phosphate particles that provides high electrolyte retention through capillary action while maintaining thin layer thickness, thereby minimizing IR losses
Solution Approach 2:
The composite structure of boron phosphate particles with appropriate pore distribution enables both good electrolyte retention and low resistance by optimizing the balance between density and porosity
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 boron phosphate matrix layer maintains electrolyte retention, reduces IR losses, and increases fuel cell efficiency and lifetime, while lowering platinum loadings and costs.
Implementation Method 1
The porous matrix layer comprises pores and solids. The solids of the matrix layer comprise at least 90% by mass boron phosphate. A phosphoric acid electrolyte is within the pores of the matrix layer
Implementation Method 2
providing chemical stability and preventing reactant mixing
Data Source
Figure 1~2
AI summary
An illustrative example embodiment of a fuel cell includes a cathode electrode, an anode electrode, and a porous matrix layer between the electrodes. The porous matrix layer includes pores and solids. The solids comprises at least 90% boron phosphate. A phosphoric acid electrolyte is within the pores of the matrix layer.