Final answer:
Fuel cells and batteries both generate electrical energy through chemical reactions, but fuel cells require continuous external reactants and do not store energy, while batteries contain a finite supply of reactants and can store energy until depleted.
Step-by-step explanation:
How Fuel Cells Differ from Batteries:
Both fuel cells and batteries are devices that convert chemical energy into electrical energy, but they operate on different principles. A battery is a self-contained unit with a finite supply of chemical reactants that convert into electricity until the reactants are depleted. On the contrary, a fuel cell is a type of galvanic cell that requires a continuous external supply of reactants, such as hydrogen or oxygen, and does not store energy in itself. In a fuel cell, energy is generated directly from the chemical reaction. It could be more efficient than combustion, typically showing an efficiency between 40% and 60%, but fuel cells face challenges in cost and reliability, restricting their broader application.
Some familiar batteries include the Leclanché dry cell, lithium-iodine batteries, and rechargeable nickel-cadmium and lead-acid batteries. The electrical output of batteries can vary, with some designs like button batteries achieving a high output-to-mass ratio. Unlike such batteries, fuel cells, like the hydrogen fuel cell, use redox chemistry but avoid combustion by employing a catalyzed electrochemical process at electrodes, often with platinum-based catalysts.