What is the difference between a battery and a fuel cell?

Electrochemical cells are devices that convert chemical energy into electrical energy through redox reactions. They can be classified into two main types: galvanic (or voltaic) cells, which generate electricity from spontaneous reactions, and electrolytic cells, which require an external power source to drive non-spontaneous reactions. Both batteries and fuel cells are types of electrochemical cells, but they operate under different principles.

Batteries are electrochemical devices that store energy chemically and release it as electrical energy when needed. They consist of one or more electrochemical cells connected in series or parallel, typically using a reversible chemical reaction. Once the reactants are consumed, the battery can be recharged by applying an external voltage, allowing the chemical reactions to reverse and restore the original materials.

Fuel cells are electrochemical devices that convert the chemical energy of a fuel, usually hydrogen, and an oxidant, typically oxygen, directly into electricity through a continuous reaction. Unlike batteries, fuel cells do not store energy; instead, they require a constant supply of fuel and oxidant to maintain operation. This makes fuel cells suitable for applications requiring a steady power output over long periods, such as in vehicles and stationary power generation.