Five methods to reduce costs and increase efficiency of PEM electrolyzers

I. Current status of PEM electrolyzer

PEM hydrogen production system is centered on PEM electrolyzer, equipped with gas-liquid separation device, fairing, gas monitor, cooling water unit, purification system and power supply and electronic control system, which together constitute a complete PEM hydrogen production system.

In the cost structure of PEM hydrogen production system, 60% of the cost is concentrated on PEM electrolyzer, and the remaining auxiliary equipment including power supply, rectifier and electronic control and purification equipment account for 40% of the cost. And 50% of the 60% PEM electrolyzer cost is membrane electrode. The membrane electrode also includes core technologies such as precious metal catalysts and proton exchange membranes.

Therefore, the cost reduction and efficiency improvement of PEM hydrogen production system mainly depend on membrane electrode, which accounts for 50% of the total cost. This is the key factor in whether PEM hydrogen production technology can achieve large-scale market application. Through the analysis of PEM megawatt-level electrolyzers, it can be found that the current challenges faced by PEM system include high performance and high cost, high electrical density and service life, high pressure and application scenarios.

The high performance of PEM electrolyzer is reflected in wind-solar coupling, fast start-stop, and high purity and high power of hydrogen production, but this is also accompanied by the problem of high cost. Since the precious metal components in the system have not been effectively replaced, the cost of PEM electrolyzer is 4 to 5 times that of traditional alkaline liquid hydrogen production.

The second is the relationship between current density and service life. At present, PEM and alkaline hydrogen production equipment on the market are increasing the current density. On the basis of the same equipment cost, increasing the current density from 1A to 2A can directly reduce the cost by 30% to 40%. Increasing the current density can quickly reduce cost pressure, but it may also shorten the service life of the equipment.

This shows that in the process of industrial operation or project operation, it is necessary to find a reasonable cost-effectiveness or suitable range between current density and service life to achieve a balance between cost and benefit.

The output pressure of the PEM system has certain advantages over alkaline hydrogen production equipment, which can reach 3-3.8 MPa, which is particularly suitable for natural gas hydrogen production and hydrogen pipeline transportation. This pressure level also matches the common pressure of urban gas pipelines (about 4 MPa).

Although the demand for high pressure is not high in the semiconductor, artificial diamond and some pharmaceutical intermediate industries, the high pressure application of PEM electrolyzers in the energy field, such as secondary purification and pressure increase, is particularly necessary.

II. Cost reduction and optimization of PEM electrolyzers

According to the current status of PEM electrolyzers, the key to their large-scale application lies in reducing costs and optimizing performance. At present, cost reduction lies in optimizing the catalyst system to reduce costs, using highly conductive support materials, and replacing them with high-performance proton exchange membranes.

1. Development and application of low-precious metal electrocatalysts

▪ Reduce manufacturing costs

By reducing the content of precious metals (platinum, iridium, and ruthenium) and improving the efficiency of the preparation process, the manufacturing cost of PEM electrolyzer electrocatalysts can be reduced and the market competitiveness of products can be improved.

▪ Improve stability

By increasing the doping of non-metallic elements and improving the crystal structure, the stability of PEM electrolyzer electrocatalysts can be improved, making them more stable and reliable in actual use.

▪ Improve performance

By adjusting the electrocatalytic activity of non-precious metals and increasing the specific surface area, the performance of PEM electrolyzer electrocatalysts can be improved, the activation energy barrier of the reaction can be reduced, and the reaction rate can be increased.

2. Design and preparation of high-conductivity support materials

▪ Improve conductivity

By selecting suitable support materials and increasing the contact area between the catalyst and the support material, the conductivity of PEM electrolyzer electrocatalysts can be improved and the resistance loss during the reaction can be reduced.

▪ Increase support strength

By increasing the strength and toughness of the support material and improving the preparation process, the support strength of the PEM electrolyzer electrocatalyst can be improved to prevent the catalyst from breaking or falling off during the reaction.

▪ Adjust microstructure

By adjusting the microstructure of the support material and changing the transport path of the reactants, the microstructure of the PEM electrolyzer electrocatalyst can be adjusted to further optimize the transport of the reactants and the reaction process.

3. Optimization and improvement of proton exchange membrane structure

▪ Selective permeable membrane

Gas permeation can be reduced by introducing a selective permeable membrane. This membrane only allows the reaction gas to pass through, while preventing the permeation of other gases.

▪ Sandwich structure

Gas permeation can be reduced by changing the sandwich structure. For example, a porous cushion layer can be introduced to divide the PEM into multiple small areas to reduce the crossover of gas products.

▪ Gas diffusion coefficient

Gas permeation can be reduced by reducing the gas diffusion coefficient. This can be achieved by increasing the rigidity of the polymer chain, introducing reinforcing materials, improving processing conditions, etc.

4. Optimization of slurry composition and improvement of physical properties

▪ Optimization of slurry composition

According to needs, adjust the catalyst, carrier components, ionomers and other additional materials in the slurry to optimize its performance.

▪ Improvement of physical properties

The quality of MEA can be improved by improving the physical properties such as particle diameter, rheology, and Zeta potential in the slurry.

▪ Introduction of additional functions

The life and reliability of MEA can be improved by introducing additional functions such as antioxidants and reducing agents.

5. Improvement and optimization of MEA processing measures

▪ Selection of coating methods

According to needs, select appropriate coating methods such as electrochemical deposition, ultrasonic spraying, transfer printing, etc. to optimize the catalytic performance of MEA.

▪ Renovation of coating equipment

According to needs, the existing coating equipment is renovated to achieve roll-to-roll coating, etc. to meet industrial needs.

▪ Monitoring of coating quality

Establish a coating quality detection system to monitor and feedback control the quality of the coating in real time to ensure the quality of MEA.