Because of their high efficiency and low emissions, fuel cells are one of the most important power sources in the energy transition, along with rechargeable batteries.

If they are operated with pure hydrogen and oxygen, the only exhaust gas produced is water vapor.

However, the price of fuel cells is one of the main reasons for the hesitant spread of the technology. That is why vehicle manufacturers prefer to rely on battery-powered vehicles.

Fuel cell heating systems also still play a minor role because of the high costs.

That would change if it were possible to produce high-performance fuel cells that did not use expensive precious metals as catalysts.

Great hopes are placed in so-called alkaline fuel cells.

They do not require precious metals, but still lag behind the widespread PEM fuel cells in terms of performance and service life.

But now a research group from Cornell University in Ithaca has built a stable alkaline fuel cell with a nickel-based catalyst.

If further development succeeds, this power source could contribute to the breakthrough of the technology.

All fuel cell types work according to the same principle

They generate electricity and heat by reacting hydrogen and oxygen in a tamed oxyhydrogen reaction to form water.

The most common type are low-temperature PEM fuel cells, which achieve an efficiency of 40 to 50 percent.

PEM stands for Polymer Electrolyte Membrane and refers to the Nafion membrane that serves as the electrolyte.

At the anode of the fuel cell, hydrogen molecules oxidize to form positively charged hydrogen ions (protons), i.e. they give off an electron.

The moistened Nafion membrane lets the protons through, but not the electrons.

The latter reach the cathode via an external circuit and supply the electrical power.

At the cathode, oxygen molecules, electrons and positive hydrogen ions react to form water.

Both here and in the anode, platinum serves as a catalyst and thus accelerates the reactions.

A PEM fuel cell contains 30 to 50 grams of platinum and accounts for around 40 percent of the manufacturing costs.

Phosphoric acid fuel cells, which use highly concentrated phosphoric acid as an electrolyte, also require the expensive precious metal.

The molten carbonate fuel cells appear to solve this problem as they operate at temperatures in excess of 600 degrees, eliminating the need for expensive catalysts.

However, it is precisely the high operating temperature that proves to be problematic because it limits the service life and causes long start-up times.

Alkaline fuel cells, on the other hand, use a basic potassium hydroxide solution as the electrolyte and inexpensive metals such as nickel as the catalyst, which lowers production costs.

At the same time, their operating temperature is mostly below 100 degrees.

Francis Thomas Bacon built the first alkaline fuel cells at the University of Cambridge back in the 1930s.

The technology first found practical application in astronautics in the 1960s, with alkaline fuel cells being used in NASA's Apollo and Space Shuttle programs, among others.

However, they require pure oxygen as the cathode gas, which increases the technical complexity.

Despite their advantages, their area of ​​application is still mainly limited to space travel and submarine drives.

This could change soon.

In an alkaline fuel cell, too, hydrogen is oxidized at the anode, while oxygen molecules and the water in the electrolyte are reduced to hydroxide ions (OH-) at the cathode.