PEM Fuel Cell Fundamentals

A fuel cell is an electrochemical device that continuously and directly converts the chemical energy of externally supplied fuel and oxidant to electrical energy. Fuel cells are customarily classified according to the electrolyte employed. The five most common technologies are polymer electrolyte membrane fuel cells (PEM fuel cells or PEMFCs), alkaline fuel cells (AFCs), phosphoric acid fuel cells (PAFCs), molten carbonate fuel cells (MCFCs) and solid oxide fuel cells (SOFCs). However, the popularity of PEMFCs, a relatively new type of fuel cell, is rapidly outpacing that of the others.

Unlike most other types of fuel cells, PEMFCs use a quasi-solid electrolyte, which is based on a polymer backbone with side-chains possessing acid-based groups. The numerous advantages of this family of electrolytes make the PEM fuel cell particularly attractive for smaller-scale terrestrial applications such as transportation, home-based distributed power, and portable power applications. The distinguishing features of PEMFCs include relatively low-temperature (under 90 °C) operation, high power density, a compact system, and ease in handling liquid fuel.