Crystec Technology Trading GmbH

1. Vacuum hot press for improved adhesive control and efficiency: Large cut films and lamination in vacuum enable better layer contact and can provide up to about 13% higher efficiency compared to R2R in certain applications. R2R typically cannot maintain a vacuum along the entire lamination path.
2. Precise alignment and uniform heat distribution: Camera‑assisted Vision Align systems and the vacuum press ensure consistent positioning, temperature and pressure distribution, minimizing defects.
3. Elimination of air bubbles in the GDL: S2S lamination allows improved degassing and thus higher‑quality gas diffusion layers (GDL).
4. Cost‑effective compact design: Vacuum lamination reduces mechanical roll systems and can be more compact and economical in purchase and operation.
5. Versatility and adaptability: S2S is more flexible regarding formats, material combinations and custom configurations — ideal for automotive and stationary applications.

In fuel cell manufacturing, the lamination process plays a decisive role in the final performance and efficiency of the fuel cell. Traditionally, the decal process has been used. In a multi‑step procedure, two sub‑gaskets, the electrode material twice (carbon web) with a catalyst layer (platinum) and the polymer membrane (Nafion®) are applied. Nafion® is a sulfonated tetrafluoroethylene polymer developed in the late 1960s and later refined by Walther Grot as a modification of Teflon®. This process requires at least three machine and process steps. It is a hot‑press method with rolls that allows continuous processing in an atmospheric environment. Despite its advantages, the decal process has limitations, particularly concerning uniformity and control over the lamination process. The mechanical press used in decal can introduce irregularities in pressure and temperature across the fuel cell and impair overall performance.
Here the Shindo vacuum hot press stands out as a revolutionary alternative and offers significant advantages over the decal process. With the vacuum hot press the lamination process is optimized and requires only a single machine and process step. This reduces production time and complexity and makes it more efficient for fuel cell manufacturers.
The main advantage of the vacuum hot press lies in its ability to perform the hot‑press operation in a vacuum environment. This controlled vacuum condition ensures better uniformity during the entire lamination process. The absence of atmospheric pressure fluctuations, as in the decal process, allows consistent and precise application of pressure and heat to the fuel cell, resulting in improved overall performance and durability.

Nafion® is a registered trademark of The Chemours Company FC, LLC

1. State‑of‑the‑art membrane pressing technology: Shindo machines include a variety of patented technologies, with membrane pressing technology being particularly noteworthy. This advanced technology enables the production of ultra‑thin 10 µm membranes, significantly improving overall fuel cell performance and efficiency. Reducing thickness from the previous 20 µm minimizes electrical resistance and optimizes gas diffusion, which enhances cell performance.
2. Technical testing and support: Shindo provides process and material testing as well as customer support beyond delivery to ensure customers receive the machines and processes best suited to their specific applications. This tailored approach builds customer confidence and supports successful fuel cell production projects.
3. Serving diverse customers: Shindo machines serve two main customer groups: automotive manufacturers seeking fuel cell stacks for electric vehicles, and hydrogen‑producing companies that need on‑site power generation, e.g. wind farms in remote locations, including offshore installations.
4. Excellent uniformity through membrane pressing: The S2S process in Shindo machines offers exceptional uniformity of pressure and temperature and outperforms what can typically be achieved with R2R processes. This uniformity is essential for manufacturing fuel cells with consistent and reliable performance.

Sheet‑to‑sheet lamination has proven to be a groundbreaking technology in fuel cell manufacturing and offers unmatched advantages over roll‑to‑roll processes. Shindo machines, with their groundbreaking innovations and commitment to technical excellence, lead this transformative process. Through precise adhesive control, superior alignment, elimination of air pockets and cost‑effective adaptability, Shindo machines have revolutionized fuel cell production. As the world moves toward 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.

Below we provide an overview of the operating principles of various fuel cell types and the manufacturing of PEMFC cells. Fuel cells are galvanic elements that convert chemical energy into electrical energy by a reversible electrochemical process. A continuously supplied fuel reacts with an oxidant. Since the energy carrier is not stored in the cell, capacity and power can be scaled independently. The redox reactions occur spatially separated at the anode and cathode and can thus be converted into electrical instead of thermal energy. The most commonly used reagents are hydrogen (H2) and oxygen (O2); their underlying reactions are shown below. These redox reactions can proceed either acid‑ or base‑catalyzed.

Basic reactions (acidic / alkaline)

In both acidic and alkaline catalyzed reactions, hydrogen gas (H₂) at the anode is converted with the release of electrons. In the acidic medium hydronium ions (H₃O⁺) are formed, while in the alkaline medium hydroxide ions (OH^-) are formed and converted to water (H₂O). At the cathode oxygen (O₂) is converted to water (H₂O) (acidic catalysis) or to hydroxide ions (OH^-) (alkaline catalysis). Thus, for the overall redox reaction in both catalytic systems hydrogen and oxygen combine to form water.

Although hydrogen and oxygen are the most commonly used combination in fuel cells, other hydrogen carriers such as methanol (CH₃OH), butane (C₄H₁₀) or natural gas (>75% methane) can also be used as fuels. Hydrogen is often stored chemically as ammonia (NH₃) and can be thermally split on site in a hydrogen generator. The H₂ generator (ammonia cracker) breaks ammonia into hydrogen and nitrogen as illustrated by the following equation:

2 NH₃ → H₂ + 3 N₂

Depending on the fuel cell type, nitrogen may need to be separated in a separate process.

A fuel cell typically consists of two catalyst‑coated electrodes and an electrolyte (ion conductor). Electrodes are mainly metal‑ or carbon‑based systems with large surface area (e.g. carbon felt). Catalysts such as ruthenium or platinum are used. The electrolyte serves to spatially separate reactants while enabling charge transport between electrodes. Both liquid and solid electrolytes are possible.

The spatially separated oxidation of a hydrogen‑containing fuel can be realized in various ways. Fuel cell types differ primarily by operating temperature, the electrolytes used and the fuels supplied and the corresponding redox reactions. Low‑temperature fuel cells (LT‑FC) operate at temperatures up to about 200 °C, whereas high‑temperature fuel cells (HT‑FC) start at around 700 °C. Due to temperature, low‑temperature fuel cells typically require catalysts based on expensive platinum‑group metals and are sensitive to impurities such as carbon monoxide. High‑temperature fuel cells can often use cheaper catalysts such as nickel and typically achieve higher efficiencies. Furthermore, fuel cells are distinguished by the electrolytes used. These include polymer electrolyte membranes (e.g. PEMFC), aqueous alkaline electrolytes (e.g. AFC), aqueous acidic electrolytes (PAFC), ionic liquid electrolytes (molten carbonate fuel cell — MCFC) and solid electrolytes (e.g. oxide ceramic SOFC).
The most common fuel cell types are listed in the table below with their properties.

The two most promising fuel cell types today are the polymer electrolyte fuel cell and the solid oxide fuel cell.

The polymer electrolyte fuel cell (PEMFC), also called proton exchange membrane fuel cell, typically operates at 10–100 °C (low‑temperature PEMFC) or 130–200 °C (high‑temperature PEMFC), depending on the electrolyte membrane used. Both variants can reach efficiencies around 60% with pure hydrogen (about 48% with natural gas as fuel). At the cathode, as described in the operating principle under acidic electrolyte, hydrogen (or a hydrogen source such as a hydrocarbon) is oxidized at the anode and oxygen from air at the cathode is reduced. Continuous supply of water to the anode is achieved by back‑diffusion through the membrane and by humidifying the reactants.

Low‑temperature PEMFC

Low‑temperature PEMFCs often use a Nafion^® polymer membrane, a sulfonated tetrafluoroethylene polymer. When hydrated, the membrane becomes proton conductive. Conductivity increases with water content. The membrane is coated on both sides with a porous electrode (typically carbon‑based) that contains a catalyst, often platinum or mixtures such as platinum‑ruthenium, platinum‑nickel or platinum‑cobalt. Special care must be taken that carbon monoxide (CO), which can occur as a by‑product when producing hydrogen from fossil sources, does not enter the fuel cell. Even CO concentrations around 10 ppm can poison the catalyst and disrupt the reaction. CO binds strongly to catalytic active sites on the membrane surface. CO can be removed by purging the fuel cell with inert gas or pure hydrogen. High CO content is avoided by shift reactions and selective CO oxidation.
In the shift reaction, CO can be converted to CO₂ and hydrogen by adding steam in a reversible reaction:
CO + H₂O ⇄ CO₂ + H₂
The equilibrium shifts toward products with increasing temperature.
Sulfur compounds and ammonia in the fuel gas are also catalyst poisons and must be kept at low ppm levels where possible.

High‑temperature PEMFC

High‑temperature PEMFCs typically use a polybenzimidazole (PBI) membrane. Phosphoric acid is doped into the PBI matrix to provide proton conductivity. Water doping as in NT‑PEMFCs is not required. At 130–200 °C the reactions are less sensitive to CO because CO desorbs more readily at higher temperatures, freeing active catalyst sites.

PEMFC advantages

• Very good cold start behavior
• Longevity (> 10 years)
• Stackable into fuel cell stacks
• High current density
• Good dynamic response
• Low operating temperature (NT‑PEMFC)
• Solid electrolyte (no risk of leaking liquids)
• CO₂-resistant electrolyte

PEMFC disadvantages

• Sensitivity to fuel impurities (CO, NH₃, sulfur compounds)
• Cleaning of reformed natural gas required
• Expensive catalyst

PEMFC development status

Currently, early series passenger cars (cars, trucks and buses), small systems and CHP units are operated with PEMFCs. There are also applications for battery replacement and electronics (e.g. backup power for laptops). Space and military applications are also under development. Power ranges from 5 to 250 kW.

The solid oxide fuel cell (SOFC) operates at temperatures of 650–1000 °C and thus belongs to high‑temperature fuel cells. Characteristic for SOFC technology is the solid oxide ceramic electrolyte. The most common material is yttria‑stabilized zirconia (YSZ). Alternatively, doped lanthanum gallate (LSGM) or gadolinium‑doped ceria (CGO) can be used. Efficiencies of up to around 70% can be achieved.
The electrolyte, the heart of the fuel cell, can be produced as a tube or as a planar membrane and is made as thin as possible to enable low‑energy transport of oxygen ions. Cathode materials can be electronically conductive perovskites based on manganese, e.g. La_0.8Sr_0.2MnO₃ (LSM). These are stable with low aging but are susceptible to "poisoning" by chromium released from stainless components that connect stacks, which can significantly reduce lifetime. Anode materials are typically nickel‑YSZ composites (Ni‑YSZ).

SOFC advantages

• Lower capital cost (no expensive catalysts)
• Can use natural gas or methane in addition to hydrogen
• High tolerance to fuel impurities
• High efficiency
• No electrolyte management required
• No electrode corrosion
• Solid electrolyte (no leaking liquids)
• CO₂-resistant electrolyte

SOFC disadvantages

• Long start‑up time due to high operating temperatures
• High temperatures require temperature‑resistant materials
• High mechanical and thermal stress

SOFC development status

Experimental prototypes of block power plants for stationary electricity generation already exist, with power outputs up to around 250 kW.