Crosslinked Ionomer Ink for Fuel Cell Catalyst Layers
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Solution Overview
Problem
Fuel cells face inefficiencies due to excessive ionomer permeation into porous substrates during the formation of catalyst layers, leading to suboptimal ionomer content, increased material costs, and reduced proton and oxygen transport resistance.
Innovation Solution
A crosslinked-ionomer solution is created by mixing a crosslinking additive, such as a heterocyclic organic base, with the ionomer premix and catalyst particles, which is then applied to porous substrates to form a catalyst layer, inhibiting ionomer penetration and optimizing catalyst utilization and permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If catalyst ink is applied onto porous GDL material, then the catalyst layer is formed, but almost 50% of the ionomer is lost into the porous GDL material
Solution Approach 1:
The patent changes the physical-chemical parameters of the ionomer by introducing crosslinking agents (such as silane crosslinking agents) that modify the ionomer's molecular structure. This crosslinking increases the ionomer's viscosity and reduces its permeability, thereby preventing excessive penetration into the porous GDL while maintaining the desired catalyst layer composition.
Solution Approach 2:
The patent creates a composite ionomer system by combining the base ionomer with crosslinking agents and catalyst particles. This composite structure forms a network that controls ionomer release and retention, optimizing both the catalyst layer formation and ionomer content precision while minimizing loss into the substrate.
2Productivity
If ionomer content in the electrode is optimized, then catalyst utilization is improved, but ionomer permeation into porous layers increases
Solution Approach 1:
By adjusting the crosslinking degree and timing, the patent optimizes the ionomer's flow properties and retention characteristics. The crosslinked ionomer maintains sufficient mobility during application to ensure proper catalyst utilization but becomes less permeable afterward, preventing excessive loss into the porous layers.
Solution Approach 2:
The crosslinking process is initiated before or during the catalyst ink application, preparing the ionomer in advance to have controlled permeability. This preliminary modification ensures that the ionomer will retain optimal content in the catalyst layer without excessive permeation into the porous substrate during the coating process.
3Loss of substance
If crosslinking additive is added to inhibit ionomer permeation, then ionomer loss is reduced, but the process complexity increases
Solution Approach 1:
The crosslinking agents are designed to react automatically with the ionomer under the existing processing conditions (temperature, pH, or time) without requiring additional equipment or complex control systems. The system self-regulates the crosslinking process, reducing ionomer permeation while maintaining simple manufacturing procedures.
Solution Approach 2:
The patent utilizes existing process parameters (such as drying temperature or pH conditions already present in the catalyst ink preparation) to trigger the crosslinking reaction. This approach achieves ionomer retention improvement without adding significant process complexity, as the crosslinking occurs under conditions already established in the manufacturing workflow.
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 reduces ionomer loss, optimizes the catalyst-to-ionomer ratio, enhances proton and oxygen transport, and increases fuel cell voltage by preventing excessive ionomer permeation into porous layers.
Implementation Method 1
mixing a crosslinking additive with the ionomer premix to thereby form a crosslinked-ionomer solution
Data Source
AI summary
Systems, methods, fuel cells, and mixtures to inhibit ionomer permeation into porous substrates using a crosslinked ionomer are described. A method includes preparing an ionomer premix, mixing a crosslinking additive with the ionomer premix to thereby form a crosslinked-ionomer solution, and adding catalyst particles to the crosslinked-ionomer solution to produce a catalyst ink. The ionomer premix includes an ionomer dispersed within a solvent. The catalyst ink includes the catalyst particles distributed homogenously therethrough. The catalyst ink may be cast onto a porous substrate and dried to thereby form a catalyst layer for use in a fuel cell.