Multilayer Porous Transport Electrode for Catalyst Stress Reduction
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Solution Overview
Problem
Conventional single-layer porous transport layers in electrochemical cells, such as polymer electrolyte water electrolyzers, suffer from mechanical stress and low catalyst utilization due to rough surfaces and heterogeneous contact pressure, leading to membrane deformation, catalyst layer degradation, and inefficient two-phase flow, which limits efficiency and durability.
Innovation Solution
A multilayer porous transport electrode composed of sintered porous layers with different particle geometries, including a fibre-based support layer, a non-defined shaped particle intermediate layer, and an electrochemically active top layer with decreasing pore sizes, optimized for improved mechanical integrity, fluid transport, and catalyst layer deposition, reducing mechanical stress and enhancing catalyst utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional single-layer porous transport layers are used, then the structure is simple and manufacturing is easy, but mechanical stress is high and catalyst utilization is low due to rough surfaces and heterogeneous contact pressure
Solution Approach 1:
The porous transport layer is divided into multiple layers with different pore sizes and structures. The first layer has larger pores for mechanical support and fluid distribution, while subsequent layers have progressively smaller pores for better catalyst contact and reduced mechanical stress, resolving the contradiction between manufacturing simplicity and mechanical stability
Solution Approach 2:
The invention uses composite porous structures combining different materials and pore geometries in each layer. This allows optimization of mechanical properties in deeper layers while improving catalyst utilization at the membrane interface, thereby enhancing reliability without significantly complicating manufacturing
2Device complexity
If conventional single-layer porous transport layers are used, then the structure is simple, but catalyst utilization is low due to rough surfaces and heterogeneous contact pressure
Solution Approach 1:
Different layers of the porous transport electrode are assigned different local qualities: deeper layers have larger pores for mechanical support and fluid transport, while layers closer to the membrane have smaller pores and smoother surfaces to maximize catalyst contact area and utilization, directly addressing the productivity issue without excessive complexity
Solution Approach 2:
The invention transitions from a single-layer structure to a multilayer structure, adding the dimensional aspect of layering with gradient pore sizes. This allows simultaneous optimization of mechanical support functions and catalyst utilization functions that cannot be achieved in a single layer, improving productivity while managing complexity
3Ease of manufacture
If conventional porous transport layers are used, then manufacturing is straightforward, but mechanical degradation occurs due to membrane deformation and catalyst layer cracking
Solution Approach 1:
The porous transport layer is segmented into multiple layers with progressively smaller pore sizes from the bipolar plate side toward the membrane. This segmentation allows the deeper layers to provide mechanical support while the shallower layers reduce contact pressure heterogeneity, preventing membrane deformation and catalyst cracking without complicating manufacturing processes
Solution Approach 2:
The invention changes the pore size parameter progressively across different layers, with larger pores in deeper layers for mechanical stability and smaller pores in shallower layers for reduced mechanical stress on the membrane and catalyst layer. This parameter gradient approach improves mechanical durability while maintaining manufacturing feasibility
4Quantity of substance
If low catalyst loadings are used, then cost is reduced, but catalyst layer segregation occurs and electrochemical activity decreases
Solution Approach 1:
The multilayer structure with decreasing pore sizes toward the membrane creates optimal local conditions for catalyst distribution. The smaller pores in shallower layers provide better catalyst confinement and contact with the membrane, ensuring uniform catalyst utilization even at low loadings and preventing segregation, thereby maintaining electrochemical performance while reducing catalyst quantity
Solution Approach 2:
The invention utilizes the porous structure of the transport layers, particularly the gradient pore sizes, to control catalyst distribution and retention. The smaller pores in layers adjacent to the membrane prevent catalyst particle aggregation and segregation, ensuring that even low catalyst loadings are effectively utilized and maintain high electrochemical activity
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 multilayer design enhances catalyst layer utilization, reduces mechanical stress, and improves fluid transport, resulting in increased efficiency, durability, and cost-effectiveness by minimizing mass, electrical, and ionic transport losses, while allowing for lower catalyst loadings and extended service life.
Implementation Method 1
facilitating two phase flow of product and educts
Implementation Method 2
having a permeability for gaseous and liquid substances
Implementation Method 3
based on a plurality of sintered porous layers with different particle geometries
Implementation Method 4
electrochemically active top layer... driving the electrochemical reaction for electrochemical decomposition of water into oxygen and hydrogen
Data Source
AI summary
A hybrid, porous transport electrode with increased efficiency, durability and catalyst utilization includes a first support porous layer and a second intermediate porous layer including fibers and non-defined shaped particles of a conductive material, a mean particle size decreasing from layer to layer from a bipolar plate towards a membrane. Said first porous layer is made from sintered fibers of the conductive material and the second layer is made from non-defined shaped particles of a conductive material, said first porous layer having a contact surface oriented towards the bipolar plate having a bigger pore size than the second porous layer having a contact surface oriented towards the membrane. An electrochemically active top layer includes an electrochemically active material or mixtures thereof on the second porous layer, the top layer having a contact surface oriented towards the membrane and smaller pore size than the second and first layers.