For PEM fuel cell and electrolyzer applications, a proton exchange membrane is sandwiched between an anode electrode and a cathode electrode. During electrochemical reaction, oxidation reaction at the anode generates protons and electrons; reduction reaction at the cathode combines protons and electrons with oxidants to generate water. To complete the electrochemical reaction, the proton exchange membrane plays a critical role that conducts protons from anode to cathode through the membrane. The proton exchange membrane also performs as a separator for separating anode and cathode reactants..
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 ..
So, you have bought a fuel cell and are ready to start using it.
Or are you?
Did you plan on any of the ancillary components you might need? Depending on who you buy the fuel cell from and what model it is will determine what components come with the fuel cell and what you will need to buy. In general, a fuel cell system needs several things in order for it to work in any system:
Hydrogen storage (which may also include Hydrogen production)
Fuel Cell system
Even if you are generating your hydrogen on-site, you will ..
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..
Knowing what's happening inside a fuel cell is a critical function, especially as fuel cells are continuing to be developed. One important aspect of this is to measure the voltage of each cell in a stack. Although this may sound trivial, it can be more complex and more expensive than it may at first appear due to high voltages, high channel counts, communication types, etc. There are a few products commercially available that are designed specifically for fuel cell voltage monitoring.
You can find the Cell Voltage Monitors (CVMs) and other electronic measurement devices currently a..
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..
PEM electrolyzers convert water and power into hydrogen and oxygen. In this article, we will focus on the principles behind an electrolyzer. Everything below refers primarily to PEM electrolyzers, but much of it can be applied to other types of electrolyzers as well. The spreadsheet linked at the bottom of this article will help you determine the cell voltage, efficiency, and output rate of hydrogen and oxygen of your electrolyzer.
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 ..
Ion exchange materials are used to purify, separate, and extract many different types of molecules, including organic and biochemical molecules. When ion exchange materials involve these ion types, there may be additional complexities involved with the interaction.Some of the phenomena that may occur are:
Secondary forces between the ionized group and counterion. These forces may consist of coordination, hydrogen, and van der Waals bonding.
The pH can affect the percent ionization.
The position of the functional groups can affect ion transport.
Hydration of organic molecules can be more complex than inorganic ions.
Organic ions may be larger than inorganic ions; thus, steric hinderances can reduce ionic interactions.
Therefore, ion exchange phenomena may be able to be explained chemically by stoichiometric reactions, but the actual ionic selectively may be determined by other interactions.