A membrane inspired by the humble cactus has the potential to significantly boost the performance of fuel cells and transform the electric vehicle industry.

The membrane, developed by scientists from Hanyang University, in South Korea, and the CSIRO, Australia's national science agency, features a water-repellent skin that can improve the efficiency of fuel cells by a factor of four in hot conditions. According to CSIRO researcher Dr. Aaron Thornton, the skin works similarly to that of a cactus plant, which thrives by retaining water in harsh and arid environments.

“Fuel cells, like the ones used in electric vehicles, generate energy by mixing together simple gases, like hydrogen and oxygen," Thornton says. "However, in order to maintain performance, proton exchange membrane fuel cells need to stay constantly hydrated."

Water and heat management in fuel cell systems are barriers to the uptake of electric vehicles. Image credit: ©CSIRO, Jesse Hawley. Fuel cells currently achieve this by placing the cells alongside a radiator, water reservoir and a humidifier, Thornton adds. But the downside is that when used in a vehicle, these occupy a large amount of space and consume significant power.

The newly developed membrane offers an alternative that draws on the cactus plant's use of tiny cracks, known as stomatal pores, that open at night when it is cool and humid and close during the day when conditions are hot and arid to help it retain water.

In the case of the membrane, water is generated by an electrochemical reaction, which is then regulated through nano-cracks within the skin. The cracks widen when exposed to humidifying conditions and close when it is drier.

“This means that fuel cells can remain hydrated without the need for bulky external humidifier equipment," says fellow CSIRO researcher Dr. Cara Doherty. "We also found that the skin made the fuel cells up to four times as efficient in hot and dry conditions.”

Professor Young Moo Lee, from Hanyang University, who led the research, says that the membrane could have significant implications for many industries, including the development of electric vehicles.

“At the moment, one of the main barriers to the uptake of fuel cell electric vehicles is water management and heat management in fuel cell systems," Lee says. "This research addresses this hurdle, bringing us a step closer to fuel cell electric vehicles being more widely available."

The technique could also be applied to existing technologies that require hydrated membranes, including devices for water treatment and gas separation, Lee adds.