To operate a PEM fuel cell, a Proton Exchange Membrane (PEM) is essential. This membrane transports hydrogen ions (protons) from the anode to the cathode while preventing the passage of electrons, which have been removed from the hydrogen atoms. These polymer membranes are designed to conduct protons through the material while being relatively impermeable to gases. As solid electrolytes (as opposed to liquid electrolytes), they are commonly referred to as Proton Exchange Membranes or Polymer Electrolyte Membranes (PEM). These membranes are crucial components in a variety of electrochemical applications and have become especially important for consumer-oriented fuel cell applications, such as in automobiles, backup power, and portable power sources. With growing demand in consumer markets, the technology continues to evolve to make these membranes more durable and capable of performing efficiently at higher temperatures.

In PEM fuel cells and electrolyzers, a polymer electrolyte membrane is placed between an anode electrode and a cathode electrode. During the electrochemical process, the oxidation reaction at the anode generates protons and electrons, while the reduction reaction at the cathode combines protons, electrons, and oxidants to produce water. The proton exchange membrane plays a critical role in facilitating the movement of protons from the anode to the cathode, completing the electrochemical reaction. Additionally, the membrane acts as a separator, keeping the anode and cathode reactants separate in both fuel cells and electrolyzers.