Development of fuel cell membrane electrode assemblies

Development of Fuel Cell Membrane Electrode Assemblies – Coating PEMs – Cheersonic

Membrane electrodes in fuel cells mainly include proton exchange membrane, catalyst and gas diffusion layer (GDL) (prepared by CCM method). In the upstream technologies of the hydrogen fuel cell industry chain, in addition to hydrogen production, hydrogen storage, transportation and hydrogenation, it also includes electrolyte membranes, catalysts, bipolar plates, gas diffusion layers, air compressors, water pumps, hydrogen pumps and other fuel cells. key materials and components.

1. Proton exchange membrane

Proton exchange membrane is the core element and key material of fuel cell. Its function is to allow only hydrogen ions (protons) that lose electrons from the anode to pass through to the cathode during the reaction, but prevent the passage of electrons, hydrogen molecules, water molecules, etc., so it needs to have the following characteristics: (1) High conductivity (highly selective ionic conduction instead of electronic conduction); (2) good chemical stability (acid and alkali resistance and redox resistance); (3) good thermal stability; (4) good mechanical properties (such as strength and (5) The gas permeability of the reaction gas is low, and the electroosmotic coefficient of water is small; (6) The processability is good and the price is reasonable.

2. Catalyst

Catalyst-Pt/C is the current mainstream, and ultra-low platinum and no platinum are the future directions. Catalysts are one of the key materials of fuel cells. Catalysts act on the hydrogen to make electrons leave the hydrogen atoms. At present, the commonly used commercial catalyst in fuel cells is Pt/C, which is composed of nano-scale Pt particles (3~5nm) and activated carbon with large specific surface area supporting these Pt particles. One of the main obstacles in the commercialization of proton exchange membrane fuel cells is expensive precious metal catalysts. The platinum loading has dropped significantly, and ultra-low platinum or no platinum is the focus of future research.

In addition to cost and resource constraints, Pt catalysts also have durability problems, mainly in terms of stability. Through the analysis of the fuel cell decay mechanism, it can be seen that the catalyst will decay under the operating conditions of the fuel cell, such as the agglomeration, migration and loss of Pt nanoparticles under the action of potentiodynamics. Aiming at these cost and durability issues, research on new highly stable and highly active low-Pt or non-Pt catalysts is currently a hot spot. Many studies have focused on improving the stability and utilization of Pt-based cathodic oxygen reduction (ORR) catalysts, improving electrode structure to reduce Pt loading and reducing fuel cell cost. Other studies have focused on the development of low-cost, resource-abundant non-platinum ORR catalysts that can completely replace platinum.

3. Gas diffusion layer

The gas diffusion layer is an easy part to reduce costs, and large-scale production is the focus of development. The gas diffusion layer is located between the smooth and catalytic layers, and its main function is to provide a transport channel for the gas participating in the reaction and the generated water, and to support the catalyst. Therefore, the performance of the base material of the diffusion layer will directly affect the cell performance of the fuel cell. The gas diffusion layer must have good mechanical strength, suitable pore structure, good electrical conductivity, and high stability. Usually the gas diffusion layer is composed of a support layer and a microporous layer. The material of the support layer is mostly hydrophobic treated porous carbon paper or carbon cloth. The contact resistance between it and the support layer enables the reaction gas and product water to be uniformly redistributed between the flow field and the catalytic layer, which is beneficial to enhance the conductivity and improve the electrode performance. Selecting the gas diffusion layer substrate with excellent performance can directly improve the working performance of the fuel cell. A diffusion layer substrate with excellent performance should meet the following requirements: (1) low resistivity; (2) high porosity and pore size distribution within a certain range; (3) certain mechanical strength; (4) good chemical stability and Thermal conductivity; (5) high cost performance. Due to the high porosity and adjustable pore size of carbon materials, they are often used to prepare gas diffusion layers, mainly carbon paper, carbon fiber cloth, non-woven fabric and carbon black paper. In addition, some use foam metal, metal mesh, etc. to prepare. In terms of technology, the preparation methods of carbon paper blanks used in the gas diffusion layer can be divided into two types: wet method and dry method. The carbon paper for diffusion layer prepared by wet papermaking technology has good and uniform pores, and the porosity can be controlled by adjusting the amount of phenolic resin, which is conducive to processing into carbon paper that meets actual needs.

Cheersonic’s fuel cell catalyst coating systems are uniquely suited for these challenging applications by creating highly uniform, repeatable, and durable coatings. Using the company’s patented ultrasonic spray head technology, it can spray uniformly and efficiently on proton exchange membranes and gas diffusion layers. Uniform catalyst coatings are deposited onto PEM fuel cells, GDLs, electrodes, various electrolyte membranes, and solid oxide fuel cells with suspensions containing carbon black inks, PTFE binder, ceramic slurries, platinum and other precious metals. Other metal alloys, including Platinum, Nickel, Ir, and Ru-based fuel cell catalyst coatings of metal oxide suspensions can be sprayed using ultrasonics for manufacturing PEM fuel cells, polymer electrolyte membrane (PEM) electrolyzer, DMFCs (Direct Methanol Fuel Cells) and SOFCs (Solid Oxide Fuel Cells) to create maximum load and high cell efficiency.

The advantages of ultrasonic spraying include：
1.Highly controllable spray that produces reliable, consistent results.
2.Ultra-low flow rate capabilities, intermittent or continuous.
3.Ultrasonic vibrations continuously break up agglomerated particles and keep them evenly dispersed; maximizing platinum utilization.
4.Corrosion-resistant titanium and stainless steel construction
5.The self-cleaning function of the ultrasonic nozzle prevents clogging.
6.The platform takes up less space.
7.80% reduction in paint consumption
8.The particle diameter is optional which can more flexibly affect the through-hole property of the coating