Fuel cells consist of two electrodes that conduct electrons – the anode and the cathode. The electrodes are separated by an electrolyte that conducts ions.
In a battery the electrical energy is chemically stored in the electrode. In a fuel cell the energy source is brought in from externally. The electrodes only have a catalytic role in the conversion.
The most simple and favored reactants are hydrogen as fuel and oxygen as oxidant. Also hydrocarbons such as natural gas and alcohols like methanol are used as fuels.
In technical systems fuel cells are coupled to stacks to achieve higher electrical voltage and meet demand. Fuel cell systems have a high efficiency which, in principle, can outperform those of combustion engines.
