Fuel cells: Sheet to sheet; vacuum lamination; Operation principal; assembly; manufacturing.
Sheet to Sheet Lamination: Revolutionizing Fuel Cell Production
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| Spezifikation | |
|---|---|
| Film supply method | Roll Feeding type |
| Cutting | Plate Knife Cutting (Sub-gasket, MEA, GDL) |
| Alignment Type | Vision Align (Pre Align, 2ndAlign , Punching Align) |
The global shift towards clean and sustainable energy sources has driven significant advancements in fuel cell technology. In the world of Proton Exchange Membrane Fuel Cells (PEMFC), precision and efficiency in component manufacturing are vital to achieving peak performance. A crucial element in fuel cell stacks is the Membrane Electrode Assembly (MEA), which brings together following components: Anode end plate, Current collector, Bipolar plate, Gasket, Gas diffusion layer (GDL), Sub-Gasket, Membrane-electrode-assembly (MEA), Cathode end plate.
Among the various manufacturing methods, Sheet to Sheet (S2S) lamination stands out as a transformative approach, and our Korean partner Shindo Ltd. has become the driving force behind this innovation. Offering a 3-layer (electrode + membrane; MEA), 5-layer (MEA + sub gasket) respectively 7 layer (MEA + sub gasket + gas diffusion layer) configurations. Shindo Machines have gained prominence in the S2S market, enabling manufacturers to achieve exceptional fuel cell performance. In the following, we will delve deeper into the advantages of Sheet to Sheet lamination over Roll to Roll (R2R) methods, explaining technical details and showcasing how Shindo Machines are shaping the future of fuel cell production.
When it comes to fuel cell manufacturing, the lamination process plays a pivotal role in determining the final performance and efficiency of the fuel cell. Traditionally, the Decal method has been used. In a multi-stage
process two sub gaskets, two times the electrode material (carbon net) with a catalyst layer (platin) and the polymer membrane (Nafion®). Nafion® is a sulfonated tetrafluoroethylene polymer (PTFE) that was developed in the late 1960s, led by
Walther Grot, as a modification of Teflon. This attachment requires a minimum of three steps in the machine and process. It involves a hot press method using rolls, allowing for continuous processing in an atmospheric environment. Despite its
advantages, Decal has limitations, especially in terms of uniformity and control over the lamination process. The physical press used in Decal can lead to inconsistencies in pressure and temperature across the fuel cell, affecting its overall
performance.
This is where Shindo's Vacuum Heat Press stands out as a revolutionary alternative, offering significant advantages over the Decal process. With the Vacuum Heat Press, the fuel cell lamination process is streamlined, requiring only a single
step in the machine and process. This reduces production time and complexity, making it more efficient for fuel cell manufacturers.
The core advantage of the Vacuum Heat Press lies in its ability to perform the heat press in a vacuum environment. This controlled vacuum condition ensures better uniformity throughout the lamination process. The absence of atmospheric pressure
variations, as in Decal, allows for consistent and precise application of pressure and heat across the fuel cell, resulting in improved overall performance and durability.
Moreover, the Vacuum Heat Press enables heat treatment by catalyst composition. This capability further enhances the fuel cell's efficiency and longevity by optimizing the catalyst layers (in the anode or cathode), leading to better electrochemical reactions within the cell.
Sheet to Sheet lamination has emerged as a leading-edge technology in fuel cell manufacturing, presenting unparalleled advantages over Roll to Roll methods. Shindo Machines, with their groundbreaking innovations and commitment to technical excellence, are at the forefront of this transformative process. By enabling precise adhesive control, superior alignment, elimination of air holes, and cost-effective customization, Shindo Machines have revolutionized fuel cell production. As the world moves towards sustainable energy solutions, the future of fuel cell technology looks promising, driven by Shindo Machines and their dedication to optimizing fuel cell efficiency and performance.
Voici un aperçu du principe de fonctionnement des piles à combustible, ainsi que la présentation de la fabrication des PEMFC (Piles à Combustible à Membrane Échangeuse de Protons). Les piles à combustible sont des éléments galvaniques qui convertissent l'énergie chimique en énergie électrique à l'aide d'un processus électrochimique réversible. À cette occasion, un carburant est continuellement ajouté et réagit avec un agent oxydant. Étant donné que la source d'énergie n'est pas stockée dans la pile à combustible, la capacité et les performances augmentent indépendamment. La réaction de réduction-oxydation (redox) sous-jacente se produit séparément à l'anode et à la cathode. Ainsi, c'est de l'énergie électrique et non de l'énergie thermique qui est produite. Les composants les plus couramment utilisés sont l'hydrogène (H2) et l'oxygène (O2), dont les réactions sous-jacentes sont indiquées ci-dessous. Cette réaction redox peut être réalisée à la fois avec un catalyseur acide et un catalyseur alcalin.
Électrolyte acide |
Électrolyte alcalin | ||||
| Anode : 2 H2 + 4 H2O → 4 H3O+ + 4 e- Cathode : O2 + 4 H3O+ + 4 e- → 6 H2O |
Anode : 2 H2 + 4 OH- → 4 H2O + 4 e- Cathode : O2 + 2 H2O + 4 e- → 4 OH- |
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| Total : 2 H2 + O2 → 2 H2O | Total : 2 H2 + O2 → 2 H2O |
Using an alkaline as well as an acidic catalyst, hydrogen gas (H2) is converted at the anode. During these reactions, electrons are released.
On this occasion an acidic environment leads to protonated water (H3O+), while in an alkaline environment hydroxide ions (OH-) react to water (H2O).
At the cathode on the other hand Oxygen (O2) is converted to water (H2O) (acidic catalyst) or hydroxide ions (OH-) (alkaline catalyst).
Therefore, the overall redox reaction shows the conversion of hydrogen and oxygen to water for both catalyst systems.
Although oxygen a hydrogen are the most common combination in a fuel cell, other hydrogen carrier like methanol (CH3OH), butane (C4H10) or natural gas (>75% methane) are worth considering as a fuel.
Frequently Hydrogen is stored chemical as ammonia (NH3). Ammonia can be decomposed thermally on site using a hydrogen generator. The H2-generator is also called ammonia splitter or rather ammonia cracker, since
ammonia is decomposed to hydrogen and nitrogen in it as shown in the following equation:
2 NH3 → H2+ 3 N2
Depending the used fuel cell type, sometimes nitrogen has to be separated using an extra process.
A fuel cell usually consists of two catalyst coated electrodes and one electrolyte. (Ion conductor). Mainly metal or carbon-based systems with high surfaces are used as electrodes (e.g. carbon felt (CF)). As a catalyst e.g. ruthenium respectively platin are common materials. In the process the electrolyte provides a spacial separation of the educts and furthermore enables transport of charge between the electrodes. Hereby liquid as well as solid electrolytes are possible.
For the realisation of the spacial separated oxidation processes of a hydrogenous fuel, various approaches are possible.
Underlying differences of fuel cells are in particular based on operating temperatures, the type of electrolytes as well as the provided fuel und corresponding redox reactions. Low temperature fuel cells (LT-FC) are operating at
up to 200 °C while high temperature fuel cells (HT-FC) start at temperatures higher than 700 °C. Due to the temperature, catalysts in low temperature fuel cells have to be based on expensive metals of the platin group. Furthermore,
contamination of the educt gases with for example carbon monoxide can damage the process heavily. Using high temperature fuel cells, cheaper catalysts based on e.g. nickel are sufficient. In addition, higher efficiency is often
possible. Moreover, fuel cells can be distinguished by the used electrolytes. Polymer electrolyte membranes (e.g. proton exchange membrane fuel cell - PEMFC), aqueous alkaline electrolytes (e.g. alkaline fuel cell - AFC), aqueous
acidic electrolytes (phosphoric acid fuel cells - PAFC), ionic electrolyte liquids (molten carbonate fuel cells - MCFC) as well as solid electrolytes (solid oxide fuel cell - SOFC) are the most commonly used types.
The most frequent types of fuel cells and their properties are shown in the following table.
| Name | Type | Electrolyte | Charge carrier | Fuel gas (Anode) | Oxidizing agent (Cathode) | Temperature (°C) | Efficiency | Application |
|---|---|---|---|---|---|---|---|---|
| Polymer electrolyte membrane fuel cell for hydrogen (PEMFC) |
Acidic low temperature oxyhydrogen gas cell | Proton-conducting polymer membrane (PEM) |
Hydronium ion (H3O+) | Hydrogen (H2) | Oxygen (O2) or air; humidified | 60-70 | Cell: 50-68 | Production vehicles, thermal power stations, Supplies for electronic |
| Polymer electrolyte membrane fuel cell for alternative fuels like methanol (DMFC), ethanol (DEFC) etc. |
Low temperature oxyhydrogen gas cell | Proton-conducting polymer membrane (PEM) |
Hydronium ion (H3O+) | Methanol-Water-Mixture (CH3OH-H2O) Methanol-Water-Mixture (C2H5OH-H2O) etc. |
Atmospheric oxygen (O2) | 60-130 | Cell: 20-30 | Electric drives, battery usage |
| Solid oxide fuel cell (SOFC) | High temperature oxyhydrogen gas cell | Oxide ceramic electrolyte (ZrO2 + Y2O3) |
Oxide ion (O2-) | Hydrogen (H2) | Atmospheric oxygen (O2) | 800-1000 | Cell: 60-65 | Thermal power stations (up to 250kW) |
| Galvanic fuel cell with alkaline electrolyte e.g. (AFC) |
Alkaline low temperature oxyhydrogen gas cell | e.g. Potassium hydroxide solution, 30% | Hydroxide ion (OH-) | Pure hydrogen (H2) | Pure oxygen (O2) | 20-90 | Cell: 60-70 | Small plants (bis 150kW); Submarine drive |
| Galvanic fuel cell with acidic electrolyte e.g. (PAFC) |
Acidic low temperature oxyhydrogen gas cell | e.g. Concentrated phosphoric acid | Hydronium ion (H3O+) | Hydrogen (H2) |
Atmospheric oxygen (O2) | 150-220 | Cell: 55 | Stationary cogenerations of power and heat |
The two most promising types of fuel cells according to the current state of art, are the Polymer electrolyte membrane fuel cell and the Solid oxide fuel cell.
The "proton exchange membrane fuel cell" (PEMFC), is also known as polymer electrolyte fuel cell (PEFC)
This kind of fuel cells operate at temperatures between 10° - 100 °C (low temperature PMEFC), respectively at 130 - 200 °C (high temperature PEFC) depending on the used electrolyte membrane.
Both Applications reach an efficiency of about 60%, using pure hydrogen gas (about 48% using fossil gas). As it is described at acidic electrolyte in the section Operating_principle,
at the cathode hydrogen, or a hydrogen source like hydrocarbons is converted at the anode, while oxygen e.g. atmospheric oxygen is converted at the cathode. The continuous water supply of the anode is achieved
using back diffusion through the membrane as well as the humidification of the educts.
Using low temperature polymer electrolyte fuel cells, usually a polymer membrane consisting of Nafion®, a sulfonated tetrafluoroethylene based fluoropolymer-polymer, is used. By humidifying this membrane,
it develops an acidic nature and therefore gets able to carry protons. The conductivity scales with increasing water Content. The membrane is coated on both sides, usually using a porous carbon electrode that has an accordingly
high surface. Commonly a catalyst consisting of platin, respectively a mixture of platin and ruthenium, platin and nickel or platin and cobalt, is integrated.
At this operating temperatures, particular attention has to be paid on carbon monoxide impurities in the hydrogen gas. For example, CO can be a side product of the hydrogen production using natural fossil oil sources and therefore
reach the fuel cell. This is important, since even small proportions of 10 ppm carbon monoxide in the fuel gas can lead to catalyst poisoning and therefor an abortion of the reaction. The reason for that CO, having a high
affinity blocks catalytically active centre of the membrane. However, flushing the fuel cell with inert gas respectively pure hydrogen, removes the poisonous CO again. A too high CO concentration can be prevented using the Shift
reaction or the selective CO oxidation.
Using the reversible shift reaction CO can be converted to CO2 and hydrogen by adding vapourised water
CO + H2O ⇌ CO2 + H2
In this process the equilibrium is shifted to product side correlating with higer temperatures.
Also sulphur compounds and ammonia in the fuel gas are catalyst poisoning and therefore have to be kept in a low ppm section if possible.
Using high temperature polymer electrolyte fuel cells, usually the polymer membrane is made of polybenzimidazole. To increase the proton conductivity, phosphoric acid is incorporated in the polybenzimidazole-matrix. Storing water as it the case in LT-PEMFC is not necessary here. In addition, reactions running at 130 - 200 °C are far more resistant to the catalyst poisoning gas carbon monoxide, since CO desorbs faster and therefore stops blocking active catalytic centres.
Advantages PEMFC
Disadvantages PEMFC
State of development PEMFC
At the moment first production vehicles (automobiles, trucks and buses), smaller plants and cogeneration are run with polymer electrolyte fuel cells. Furthermore, there are applications in battery usage, portable electronic supply (e.g. notebooks). Applications in space travel or military use are also developed at the moment. Here performances between 5 and 250 kW can be achieved.
Die "solid oxide fuel cell" (SOFC) is operating at 650 - 1000°C and therefore is part of the high temperature fuel cells. The solid electrolyte made of oxide ceramic is characteristic for the SOFC technique. The most common used material here is yttrium oxide stabilised zirconium oxide (YSZ). An alternative strontium- and magnesium doped lanthan-galium oxide (LSGM) or gadolinium doped cerium oxide (CGO) can be used. Here an efficiency up to 70% can be achieved. The electrolyte as the core element of the fuel cell is manufactured as a tube or alternatively as planar membrane. It has to be designed quite thin, to guarantee a low energy transport of oxygen ions. The cathode material can be made out of perovskites based on manganese e.g. La0.8Sr0.2MnO3 (LSM). These are attractive for their high durability and resistance to ageing. However, they are vulnerable to chrome poisoning, which can be set free from stacks connecting compounds made out of chrome steel and therefore reduce the life span significantly. At the anode in contrary materials like nickel and yttrium oxide stabilised zirconium oxide (Ni-YSZ) are used.
Advantages SOFC
Disadvantages SOFC
State of development SOFC
At the moment experimental prototypes of block unit power stations for stationary electricity supply exist. Here performances between up to 250 kW can be achieved.
