Porous transport layers for electrochemical production of hydrogen and green molecules
Electrochemical devices will play a crucial role as one of the solutions for the energy transition towards renewable energy sources. Technologies such as water electrolyzers, fuel cells and redox flow batteries help enable widespread electrification while coping with intermittent energy production. Both cost and performance of these energy solutions have seen a tremendous improvement over the past decade.
At the heart of these devices is the so-called stack where electrochemical reactions take place. Key components include membrane/separator, electro-catalyst, porous transport layer (PTL) and bipolar plate.
A porous transport layer, sometimes referred to as gas diffusion layer (GDL) or current collector, has multiple functionalities that influence performance and durability of the electrochemical device. An ideal porous transport layer should:
- Enable efficient flow of gaseous/liquid reactants/products
- Have high electrical, and thermal, conductivity
- Be corrosion resistant towards the specific environment
- Have tuned interface towards other components such as membrane and electro-catalyst
Sintered metal fiber media as porous transport layer
Sintered metal fiber media are excellent candidates as porous transport layer for any electrochemical device. They possess intrinsic high permeability and strength
, the metal/alloy can be selected to match corrosion requirements, fiber diameter / porosity can be tuned to change surface / contact area.
Sintered metal fiber media have pore sizes in the µm-range
. Compared to sintered metal powder, higher porosity, and thus permeability, can be achieved at similar pore size. Compared to metal foam, sintered metal fiber media enable a stepwise reduction in pore size and corresponding increase in surface area.
A proven track record in electrochemical applications
Bekaert has a history of more than 20 years in providing these structures to various electrochemical applications, including water electrolysis, electrochemical CO2 reduction and fuel cells. Several of these products have been commercialized. Bekaert is a proud partner of various leading technology developers.
A selection of recent papers where Bekaert’s sintered metal fibers have been used as porous transport layers:
Tobias Schuler et al 2019 J. Electrochem. Soc. 166 F270
Polymer Electrolyte Water Electrolysis: Correlating Porous Transport Layer Structural Properties and Performance: Part I. Tomographic Analysis of Morphology and Topology
Tobias Schuler et al 2019 J. Electrochem. Soc. 166 F555
Polymer Electrolyte Water Electrolysis: Correlating Performance and Porous Transport Layer Structure: Part II. Electrochemical Performance Analysis
Stefanie M.A.Kriescher et al 2015 Electrochemistry Communications Volume 50, January 2015, Pages 64-68
A membrane electrode assembly for the electrochemical synthesis of hydrocarbons from CO2(g) and H2O(g)
Carbone et al 2020 International Journal of Hydrogen Energy Volume 45, Issue 16, 20 March 2020, Pages 9285-9292
Assessment of the FAA3-50 polymer electrolyte in combination with a NiMn2O4 anode catalyst for anion exchange membrane water electrolysis
Bekaert offers sintered metal fiber media which can be modified depending on customer request. Ni media is available for alkaline water electrolysis (AWE) and anion-exchange-membrane (AEM) water electrolysis, Ti media for proton-exchange-membrane (PEM) water electrolysis and Cu for electrochemical CO2 reduction.
- Metal: 316L, Ti, Ni, Cu
- Fiber diameter range
- 2 – 40 µm (316L)
- 10 - 50 µm (Ti, Ni, Cu, ...)
- Porosity: 40% - 90%
- Thickness: 100 µm - 2 mm
- Dimensions: shape and cutting customizable according to customer need
- Multilayers: combination of multiple fiber diameters enabling structure with pore gradient
- Coatings: Additional protective coating (e.g. Pt) for increased durability
Bekaert is partner of European H2020 project LOTER.CO2M, which aims to develop advanced, low-cost electro-catalysts and membranes for the direct electrochemical reduction of CO2 to methanol by low temperature CO2-H2O co-electrolysis.