Knowledge of AEM Water Electrolysis for Hydrogen Production
Knowledge of AEM Water Electrolysis for Hydrogen Production – Electrolyzer Coatings – Cheersonic
Solid polymer anion exchange membrane water electrolysis (Anion Exchange Membrance), referred to as AEM, is one of the most cutting-edge water electrolysis technologies. Currently, only a few companies are trying to turn it into commercial operation, and there are very few related applications and demonstration projects.
When the AEM equipment is running, the raw water enters from the cathode side of the AEM equipment, and the water molecules participate in the reduction reaction at the cathode to obtain electrons, generating hydroxide ions and hydrogen. After the hydroxide ions reach the anode through the polymer anion exchange membrane, they participate in the oxidation reaction to lose electrons and generate water and oxygen. Sometimes a certain amount of potassium hydroxide or sodium bicarbonate solution is added to the raw water as an auxiliary electrolyte, which helps to improve the working efficiency of the AEM electrolysis equipment.
Anion exchange membrane (AEM) water electrolysis hydrogen production technology combines the advantages of alkaline water electrolysis technology and PEM water electrolysis technology. It has higher current density and response speed, higher energy conversion efficiency, and the electrolyte is pure water or low-concentration alkaline solution, which alleviates the corrosion of strong alkaline solution to the equipment. In addition, AEM technology can use non-precious metals such as Fe and Ni as electrode catalysts, and its device manufacturing cost is significantly reduced compared with PEM water electrolysis technology. This technology is generally superior to alkaline water electrolysis hydrogen production technology, but it is still in the experimental research and development stage and has not been commercialized on a large scale. There are key problems that need to be solved urgently.
Main components and features
AEM electrolysis cell is the basic unit of the AEM electrolysis system. Multiple AEM electrolysis cells together constitute the AEM electrolysis module. A large number of AEM electrolysis modules and multiple auxiliary systems together constitute the AEM water electrolysis system. The AEM electrolysis module is similar to the PEM electrolyzer in structure, and its auxiliary systems include oxygen treatment and drying systems, water tanks, water treatment and purification systems, and AC-DC converters.
Anion exchange membrane The key component of the AEM electrolyzer is the anion exchange membrane group, which consists of an organic cationic polymer skeleton and cations covalently attached to the skeleton. Cathode materials, anode materials, and anion exchange membranes are the core of the AEM electrolyzer, directly affecting the working efficiency and equipment life of the AEM electrolyzer.
The anion exchange membrane can transfer hydroxide ions from the cathode to the anode, and has high anion conductivity and very low electronic conductivity. The anion exchange membrane has excellent chemical stability (resistance to strong alkaline environments in local areas) and extremely low gas permeability (isolation of gas permeation, preventing explosions caused by the mixing of hydrogen and oxygen).
Anion exchange membranes have the problem of difficulty in balancing ionic conductivity and stability (alkali resistance and mechanical properties) in a strong alkaline environment. Although the electrolyte can be pure water or low-concentration alkaline solution, a local strong alkaline environment will be formed on the surface of the anion exchange membrane during electrolysis, causing the anion exchange membrane to gradually degrade due to OH- attack, causing membrane perforation, resulting in battery short circuit, and making the anion exchange membrane water electrolysis hydrogen production device unable to operate for a long time.
Therefore, the key link of AEM technology at the current stage is to develop anion exchange membranes with high ionic conductivity and strong alkaline resistance.
At present, polymers are mostly used as the main skeleton material of anion exchange membranes. Since AEM water electrolysis is still in the research and development stage, the current materials are not the most suitable and are still in the process of research and development. Aromatic polymers are currently used more, and the molecular structure of polymers directly determines the stability of membrane materials. At present, AEM exchange membranes have the following problems:
- Aromatic polymers will be slowly degraded when operating for a long time in an alkaline environment, resulting in chain breakage and mechanical performance degradation, affecting the stability and system life of AEM water electrolysis equipment.
- The mechanical stability of anion exchange membranes is on a downward trend, and holes are prone to appear. Compared with the conductivity of hydrogen ions in proton exchange membranes, the conductivity of hydroxide ions in anion exchange membranes is much lower. Researchers have to make thinner anion exchange membranes to maintain the working efficiency of AEM electrolyzers, which causes the mechanical stability of anion exchange membranes to decrease.
In addition to the polymer skeleton, there are also cationic groups adsorbed on the polymer skeleton. The breakage of cationic groups will cause the AEM ion exchange capacity (IEC) to decrease, while reducing the OH-conductivity.
Anode and cathode materials Anode and cathode materials must have strong catalytic activity and porosity to facilitate the catalytic decomposition of water and timely output of the produced hydrogen and oxygen. It has high electronic conductivity and anion conductivity to facilitate the smooth electrode reaction. At present, the main nickel-iron alloy used has a wide range of sources, low cost, and strong catalytic activity for the decomposition of water. In addition, since AEM does not operate in a highly corrosive environment, its electrode materials do not need to add precious metal catalysts such as ruthenium and titanium, which greatly reduces the manufacturing cost. The anion exchange membranes currently developed still cannot take into account both work efficiency and equipment life. The research on AEM mainly focuses on the development of suitable and efficient polymer anion exchange membranes.
Secondly, in the laboratory research and development stage, a small amount of precious metals will still be added to the electrode materials, so the development of low-cost and efficient non-precious metal catalysts is also one of the focuses of AEM research.
The overall industrialization level of AEM electrolysis equipment is low and is in the early research and development stage. Only a few companies in the world are trying to commercialize AEM technology.
Hydrogen production by electrolysis of water is the most advantageous method for producing hydrogen. Utrasonic coating systems are ideal for spraying carbon-based catalyst inks onto electrolyte membranes used for hydrogen generation. This technology can improve the stability and conversion efficiency of the diaphragm in the electrolytic water hydrogen production device. Cheersonic has extensive expertise coating proton exchange membrane electrolyzers, creating uniform, effective coatings possible for electrolysis applications.
Cheersonic ultrasonic coating systems are used in a number of electrolysis coating applications. The high uniformity of catalyst layers and even dispersion of suspended particles results in very high efficiency electrolyzer coatings, either single or double sided.
About Cheersonic
Cheersonic is the leading developer and manufacturer of ultrasonic coating systems for applying precise, thin film coatings to protect, strengthen or smooth surfaces on parts and components for the microelectronics/electronics, alternative energy, medical and industrial markets, including specialized glass applications in construction and automotive.
Our coating solutions are environmentally-friendly, efficient and highly reliable, and enable dramatic reductions in overspray, savings in raw material, water and energy usage and provide improved process repeatability, transfer efficiency, high uniformity and reduced emissions.
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