PEM Water Electrolysis Hydrogen Production Technology

PEM Water Electrolysis Hydrogen Production Technology – Cheersonic

PEM water electrolyzer adopts PEM to conduct protons, isolate the gas on both sides of the electrode, and avoid the shortcomings associated with AWE using strong alkaline liquid electrolyte. PEM water electrolyzer uses PEM as electrolyte and pure water as reactant. In addition, the hydrogen permeability of PEM is low, so the purity of hydrogen generated is high, and only water vapor needs to be removed; The electrolytic cell adopts zero spacing structure, with low ohmic resistance, which significantly improves the overall efficiency of the electrolytic process and is more compact in size; The pressure regulation range is large, and the hydrogen output pressure can reach several megapascals, adapting to the rapidly changing renewable energy power input. Therefore, PEM water electrolysis hydrogen production is a promising green hydrogen production technology path.

It should also be noted that the bottleneck of PEM water electrolysis hydrogen production is cost and life. In the cost of electrolytic cell, bipolar plate accounts for about 48%, and membrane electrode accounts for about 10%. The current international advanced level of PEM is: single battery performance is 2 A · cm – 2@2 5. The total platinum catalyst loading is 2~3 mg/cm2, and the stable operation time is 6 × 104 ~8 × 104 h, the cost of hydrogen production is about US $3.7 per kilogram of hydrogen. The research on reducing the cost of PEM electrolyzer focuses on the core components such as membrane electrode, gas diffusion layer and bipolar plate based on catalyst and PEM.

1. Electrocatalyst

Since the anode of PEM electrolyzer is in a strong acidic environment (pH ≈ 2) and the electrolysis voltage is 1.4~2.0 V, most non precious metals will corrode and may combine with sulfonate ions in PEM, thus reducing the proton conduction ability of PEM. The research on the electrocatalyst of PEM electrolyzer mainly focuses on the noble metals/oxides such as Ir, Ru, and their binary and ternary alloys/mixed oxides, as well as supported catalysts supported on titanium materials.

According to the technical planning goal, the total load of platinum group catalyst on the membrane electrode should be reduced to 0.125 mg/cm2, while the current anode iridium catalyst load is on the order of 1 mg/cm2, and the cathode Pt/C catalyst Pt load is about 0.4~0.6 mg/cm2.

Ru has higher electrocatalytic oxygen evolution activity than Ir, but its stability is poor; The activity and stability of the catalyst can be improved by forming a stable alloy with Ir.

Due to the acidic environment, high anode potential, good conductivity and other requirements for PEM hydrogen production by water electrolysis, it is difficult to develop non noble metal catalysts or non-metallic catalysts. It is estimated that Ir will still be the main catalyst used in large-scale electrolytic cells in a certain period of time. A better way to reduce the cost of hydrogen production and the amount of noble metal catalyst in the future is to develop ultra-low loading or ordered membrane electrodes.

2. Diaphragm material

In terms of PEM, the commonly used products are DuPont Nafion series films, Dow Chemical Dow series films, Asahi Nippon Co., Ltd. Flemion series films, Asahi Kasei Co., Ltd. Aciplex-S series films, Deshan Chemical Neosepta-F, etc.

In order to further improve the performance of PEM and reduce the cost, on the one hand, the mechanical properties of PEM can be improved by using the reinforced composite scheme, which is conducive to reducing the thickness of the film; On the other hand, the membrane resistance and electrolytic energy consumption can be reduced by increasing the ionic conductivity of the membrane, which is conducive to improving the overall performance of the electrolytic cell.

3. Membrane electrode

The anode of PEM electrolytic water shall be resistant to acid environment corrosion and high potential corrosion, and shall have proper hole structure for gas and water to pass through. Due to the reaction conditions of PEM water electrolysis, membrane electrode materials commonly used in PEM fuel cells (such as carbon materials) cannot be used as water electrolysis anodes.

Improving the performance of the current collector can also improve the performance of the electrolytic cell.

4. Bipolar plate

The bipolar plate and flow field account for a large proportion of the cost of the electrolytic cell. Reducing the bipolar plate cost is the key to control the cost of the electrolytic cell. In the harsh working environment of PEM electrolyzer anode, if the bipolar plate is corroded, it will lead to metal ion leaching, which will pollute PEM. Therefore, the common protection measure for bipolar plate is to prepare a layer of anti-corrosion coating on the surface.

5. Electrolyser stability

Many research teams focus on exploring the attenuation mechanism of various components in the PEM electrolyzer. It is found that the falling off of catalyst and membrane, the change of water flow, the corrosion of water supply pipeline, etc. will lead to the increase of ohmic impedance. After the membrane electrode structure is damaged, it will induce the gas penetration on both sides and reduce the hydrogen purity. Temperature/pressure change, current density and power load cycle will also affect the attenuation rate of components.

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.

In hydrogen fuel cell production, PEM electrolyzer coating systems are ideal for spraying carbon-based catalyst inks onto electrolyte membranes. These systems are fully automated, capable of dual side coating, and enable different catalyst formulations to be applied to each side of the membrane. Durability and repeatability of the coating are proven superior to other coating methods, often providing higher efficiencies with extended lifetimes of the coated PEM.

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.