Cells contain chemicals which react to produce electricity.
The voltage produced by a cell is dependent upon a number of factors including the type of electrode and electrolyte.
A simple cell can be made by connecting two different metals in contact with an electrolyte.
Batteries consist of two or more cells connected together in series to provide a greater voltage.
In non-rechargeable cells and batteries the chemical reactions stop when one of the reactants has been used up. Alkaline batteries are non-rechargeable.
Rechargeable cells and batteries can be recharged because the chemical reactions are reversed when an external electrical current is supplied.
Fuel cells are supplied by an external source of fuel (eg hydrogen) and oxygen or air.
The fuel is oxidised electrochemically within the fuel cell to produce a potential difference.
The overall reaction in a hydrogen fuel cell involves the oxidation of hydrogen to produce water.
Hydrogen fuel cells offer a potential alternative to rechargeable cells and batteries.