GAS DIFFUSION LAYERS
Gas Diffusion Layers (GDLs) are crucial components for most electrochemical processes, including Proton Exchange Membrane (PEM) fuel cells and electrolyzers, Direct Methanol Fuel Cells (DMFCs) and Phosphoric Acid Fuel Cells (PAFCs), and all other electrochemical devices.
In PEM fuel cells, the porous carbon allows for simultaneous transfer of gases and liquids through the media and provides an electrical pathway for electrons to move from the reaction zone to the current collector or vice versa.
Electrolyzers cannot use carbon based GDLs on the anode. The reaction on the anode will cause the carbon to degrade. The carbon GDL will be consumed, leaving a physical gap that will give poor electrical contact between anode electrocatalyst and anode flow field or anode current collector, eventually completely stopping operation of the electrolyzer.
Gas Diffusion Layers serve very important functions within the electrochemical cell. Some of those functions include, preventing flooding by removing by-product water from the catalyst layer, transferring heat during operation, providing a gas-diffusion pathway from the flow channel to the catalyst layer and mechanically reinforcing the MEA, just to name a few.
Wet Proofing is a Teflon treatment designed to improve water transport through a GDL. Water retention, or flooding, can result in power loss in PEM fuel cells.
A carbon Micro-porous Layer (MPL) is intended to prevent catalyst from seeping into the interior of the GDL during the catalyst coating process, decrease flooding and reduce contact resistance between the catalyst layer and the GDL.
FuelCellsEtc is capable of custom wetproofing or adding MPL to many of the GDLs offered by Fuel Cell Store. We are also the sole manufacturer of ELAT® Carbon Cloth.
ELAT® Hydrophilic Plain Cloth is an excellent choice of Gas Diffusion Layer for flow battery and other liquid electrolyte applications. The carbon cloth has no microporous layer, but has been treated with a proprietary treatment to create a hydrophilic nature in the cloth.
ELAT® LT1400 is our carbon cloth with single-sided carbon microporous layer. It is ideal for gaseous electrochemical applications. The hydrophobicity provided by the MPL improves water management within the cell, creating an even distribution for the fuel or oxidant to reach the catalyst layer.
ELAT® LT2400 is a special carbon cloth that contains carbon-based microporous layers on both sides of the carbon cloth substrate. This makes this GDL perfect for electrochemical cells with two reactions occurring within the same electrode. Having two MPLs will allow you to apply two or more catalysts with different functionalities, where two separate reactions are occurring simultaneously, such as oxidization of a chemical fuel to generate a hydrogen on the first catalyst and then the oxidation of the H2 on the second catalyst for the main electrochemical reaction. This unique feature makes ELAT® LT2400 perfect for niche electrochemical devices that requires the need of multiple catalysts for simultaneously occurring reactions such as consuming liquid chemical hydride or hydrazine hydrate to generate hydrogen gas first and then consume this generated hydrogen. This unique and advanced GDL can also be used in conventional PEM or alkaline electrochemical devices.