Gas Diffusion Layers(GDLs) are one of the components in different types of fuel cells including, but not limited, to Proton Exchange Membrane and Direct Methanol fuel cells. Gas Diffusion Layers serve to provide conductivity in the cell and control the contact between the reactant gases and the catalyst.
Carbon Paper Gas Diffusion Layers
Carbon Paper Gas Diffusion Layers (GDLs) (e.g. Sigracet, Freudenberg, Toray, etc) tend to be thinner and more brittle than Carbon Cloth Gas Diffusion Layers (e.g. ELAT™, AvCarb , CT Carbon Cloth with MPL, etc.). Each variation has different mass transport, porosity, hydrophobicity and conductivity, among other things. Every manufacturer releases their own technical data sheet, so trying to parse all the information and find like qualities can be quite time-consuming and difficult. We have broken down the information into an easily digestible ..
We've spoken already about Gas Diffusion Layer (GDL) selection for a Fuel Cell; today we will cover some GDL considerations for Electrolyzers.
The Gas Diffusion Layer (GDL) plays several critical roles in a typical fuel cell application and is often integrated as part of the Membrane Electrode Assembly (MEA). Typical applications that use GDLs consist of Polymer Electrolyte Membrane Fuel Cells (PEMFC) and Direct Methanol Fuel Cells (DMFC). When a GDL is coated with a catalyst it is then referred to as a Gas Diffusion Electrode(GDE), which is sometimes sold or installed separately from the Membrane or MEA. Acting as an electrode is the easy part of the GDL/GDE, though.
What Does a Gas Diffusion Layer (GDL) Consist Of..
Why is an activation procedure or break-in necessary for a membrane electrode assembly (MEA)? A large reason for performing an activation procedure or break-in is to properly humidify the membrane portion of the MEA that was dried out during the hot press stage of the membrane electrode assembly (MEA) production. MEAs will not work well when they are not fully humidified (see article: Why is Humidity / Moisture Control Important in a Fuel Cell?).
How do I Humidify a Membrane Electrode Assembly (MEA)?
You can re-humidify the MEA by soaking it in deionized water. ..
To properly operate a fuel cell, the proton exchange membranes must stay hydrated. If they are not fully humidified the conductivity decreases and therefore more energy is consumed during the proton transportation phenomenon. If it gets too dry the membrane essentially stops functioning as a proton transporter. Since a hydrogen fuel cell consumes hydrogen and oxygen to generate electricity and water, it would seem that there should be plenty of water around. This creates a problem with potentially flooding the catalyst layer if the excess water is not removed via gas flow to drive the water..
There are numerous methods that have been developed for working with ion exchange materials. In this blog post, we will describe a few basic methods commonly used in ion exchange research to help a student or new scientist to work with these materials.
Conventional ion exchange processes use chemical reactants in solution for the ion exchange process. However, ion exchange processes are not just chemically driven, are also electrically driven. An example of an electrically driven ion exchange process is electrodialysis, (also known as electrodeionization), where ionizable species are removed from liquids using electrically active media and the electrical potential as a driving force for ion transport. Electrodeionization can also be used for water treatment, separation of electrolytes from non-electrolytes, concentrating or depletion of i..
As we saw in the previous blog post, the process of ion exchange is influenced by a very large number of factors. The primary mode of ion transport is diffusion, which is process of the movement of atoms, ions, molecules, or energy from a region of high concentration to a region of low concentration.
The rate of ion exchange depends on the rates of the chemical (ionic) reactions in the ionic exchange material (membranes, dispersions, beads, pellets, etc.), but it is often limited by the diffusion processes. The ion exchange process maybe primarily controlled by diffusion, which is dependent upon the material layers, structure, thickness and reactant rate of contact on the surface of the material. This blog post introduces the factors to consider when thinking about the kinetics of the ion exchange reactions.
Mechanism of Ion Exchange Processes
A common ion-exchange system is an ..