For PEM fuel cell and electrolyzer applications, a polymer electrolyte membrane is sandwiched between an anode electrode and a cathode electrode. During electrochemical reaction, oxidation reaction at the anode generates protons and electrons; reduction reaction at the cathode combines protons and electrons with oxidants to generate water. To complete the electrochemical reaction, the proton exchange membrane plays a critical role that conducts protons from anode to cathode through the membrane. The proton exchange membrane also performs as a separator for separating anode and cathode reactants in fuel cells and electrolyzers.
What is the Difference Between Cation and Anion Exchange Membranes?
Cation Exchange Membranes (CEM) that are based on fluorinated polymer and sulfonic acid groups are used as a major membrane for Proton Exchange Membrane Fuel Cells (PEMFC) because of their excellent proton conductivity and durability. On the other hand, Anion Exchange Membranes (AEM) that are based on quaternary ammonium groups and hydrocarbon polymer backbone have been considered to have low thermal durability and low OH- conductivity under the condition of the fuel cell.