User:TheChemistTree/Proton-exchange membrane

History
Early proton-exchange membrane technology was developed in the early 1960's by Leonard Niedrach and Thomas Grubb, chemists working for the General Electric Company. Significant government resources were devoted to the study and development of these membranes for use in NASA's Project Gemini spaceflight program. A number of technical problems led NASA to forego the use of proton-exchange membrane fuel cells in favor of batteries as a lower capacity but more reliable alternative for Gemini missions 1-4. An improved generation of General Electric's PEM fuel cell was used in all subsequent Gemini missions, but was abandoned for the subsequent Apollo missions. Nafion, a fluorinated ionomer that is today the most widely utilized proton-exchange membrane material, was developed by DuPont plastics chemist Walther Grot who also demonstrated its usefulness as an electrochemical separator membrane.

Applications
The primary application of proton-exchange membranes is in PEM fuel cells. These fuel cells in turn have a wide variety of commercial and military applications including in the aerospace, automotive, and energy industries.

Early PEM fuel cell applications were centered on the aerospace industry, with the then-higher capacity of fuel cells compared to batteries making them ideal as NASA's Project Gemini targeted longer space missions than had previously been attempted.

The automotive industry as well as personal and public power generation are the largest markets for proton-exchange membrane fuel cells today. PEM fuel cells are popular in automotive applications due to their relatively low operating temperature as well as their ability to start up quickly, even at below-freezing conditions. As of March 2019 there were 6,558 fuel cell vehicles on the road in the United States, with the Toyota Mirai being the most popular model. California leads the United States in hydrogen refueling stations with 43, and further investment in the technology is budgeted for. PEM fuel cells have seen successful implementation in other forms of heavy machinery as well, with Ballard Power Systems supplying forklifts based on the technology. The primary challenge facing automotive PEM technology is the safe and efficient storage of hydrogen, an area of high research activity currently.

Polymer electrolyte membrane electrolysis is a technique by which proton-exchange membranes are used to decompose water into hydrogen and oxygen gas. The proton-exchange membrane allows for the separation of produced hydrogen from oxygen, allowing either product to be exploited as needed. This process has been used variously to generate hydrogen fuel and oxygen for life-support systems in vessels such as US and Royal Navy submarines. A recent example is the construction of a 20 MW Air Liquide PEM electrolyzer plant in Québec. Similar PEM-based devices are available for the industrial production of ozone.