A new type of membrane, inspired by the cactus plant, could significantly boost fuel cell performance.
Keeping fuel cells hydrated
One of the main barriers to the uptake of fuel cell electric vehicles is water management and heat management in fuel cell systems.
Fuel cells, like the ones used in electric vehicles, generate energy by mixing together simple gases, like hydrogen and oxygen. However, in order to maintain their performance, proton exchange membrane fuel cells – or PEMFCs – need to stay constantly hydrated.
This is currently achieved by placing the cells alongside a radiator, water reservoir and a humidifier, but these extra components occupy a large amount of space in a vehicle and consume significant power.
New cactus-inspired solution offers an alternative
To solve this issue, our scientists teamed up with Hanyang University in Korea, and looked to the cactus plant for inspiration.
A cactus plant has tiny cracks, called stomatal pores, which open at night when it is cool and humid, and close during the day when the conditions are hot and arid. This helps it retain water.
The team developed a membrane that works in a similar way. 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 up when it is drier, meaning fuel cells can remain hydrated without the need for bulky external humidifier equipment.
We also found that the skin made the fuel cells up to four times as efficient in hot and dry conditions.
This research addresses the hurdle of fuel cell hydration and brings us a step closer to fuel cell electric vehicles being more widely available.
The technique could also be applied to other existing technologies that require hydrated membranes, including devices for water treatment and gas separation.
For this study, Hanyang University conceived and designed the experiments. Using characterisation and modelling expertise, CSIRO researchers were then able to determine how the membranes behaved under changing humidity. The cross-continent team has been working together for over ten years.