Proton Exchange Membranes

Proton Exchange Membranes

Proton exchange membrane is a semi-permeable membrane, which was first used in seawater desalination and chlor-alkali industry. In recent years, with the development of new energy technologies such as fuel cells and vanadium flow batteries, proton exchange membranes have become key materials in the field of new energy. Such membranes help to convert chemical energy into electrical energy efficiently and minimize the impact on the environment.

Typical Applications

• Fuel cells

Proton exchange membranes are critical components of fuel cell systems. They separate the reactant gases, provide the electrolyte for energy-generating electrochemistry, and facilitate proton transport from the anode to the cathode. At present, researchers have been working on the development of proton exchange membranes with high proton conductivity, low electronic conductivity, low electroosmotic drag coefficient, good chemical and thermal stability, low permeability to fuel, good mechanical properties and low cost.

Figure 1. Schematic design of the proton exchange membrane fuel cell ^[1].

• Vanadium flow batteries

Figure 2. Schematic of a vanadium flow batteries system ^[2].

Proton exchange membranes are one of the essential components of high-performance vanadium flow batteries due to their long working life and high conductivity at high current densities. Proton exchange membranes act as separators of anolyte and catholyte to avoid vanadium ion crossover. They can also act as proton conductors, thereby helping to improve the voltage efficiency of vanadium flow batteries.

• Hydrogen production by water electrolysis

Proton exchange membrane electrolysis is industrially important as a green source of high-purity hydrogen. Proton exchange membrane water electrolysis is produced by pumping water to an anode where the water is spilt into oxygen (O₂), protons (H) and electrons (e^+-). These protons reach the cathode side through a proton conducting membrane. On the cathode side, the protons and electrons recombine to produce hydrogen. This high-purity hydrogen production technology has the characteristics of high current density, high energy efficiency, small mass volume, easy handling and maintenance.

Figure 3. Schematic illustration of proton exchange membrane water electrolysis ^[3].

References

1. Peighambardoust, S. J.; Rowshanzamir, S. et al. Review of the proton exchange membranes for fuel cell applications. International Journal of Hydrogen Energy. 2010, 35(17): 9349-9384.
2. Thiam, B. G.; Vaudreuil, S. Recent membranes for vanadium redox flow batteries. Journal of The Electrochemical Society. 2021, 168(7): 070553.
3. Kumar, S. S.; Himabindu, V. Hydrogen production by PEM water electrolysis–A review. Materials Science for Energy Technologies. 2019: 442-454.