Renewable energy may be the future, but storing electricity generated by wind and solar remains a challenge. University of Waterloo researchers are looking to nature and 3D printing for a potential solution that could make large-scale energy storage more efficient. Wind farms rely on wind, and solar farms depend on sunlight, but electricity is still needed when the wind is calm and after the sun goes down. “During the day there might be more sun, but actually during the night we turn on our lights more,” said Maxime van der Heijden, an assistant professor of chemical engineering at the University of Waterloo. The research team is working with redox flow batteries, which differ from conventional lithium-ion batteries. “They store energy in liquid electrolytes held in external tanks,” van der Heijden said. Because the energy is stored in liquid electrolytes outside the battery itself, redox flow batteries are considered a promising option for large-scale energy storage. The Waterloo researchers are now trying to make the technology more efficient by changing the shape of a key component called an electrode. The team uses 3D printing to create electrodes with complex, nature-inspired structures. PhD student Zain Qamar said the material used in the electrode has “very high conductivity” compared with other two-dimensional materials. The researchers drew inspiration from patterns found in nature. “They are also found in butterfly wings or in sea urchins. And that’s why we are interested in these structures and 3D printing,” van der Heijden said. The team found an electrode with a diamond-shaped structure was 52 per cent more efficient than one using a simple cubic design. “This is a real significant improvement by only changing the structure that you’re using,” van der Heijden said. The 3D printed material is then heat-treated, transforming it into conductive carbon that can be used inside the battery. Qamar said the electrode shrinks to about 75 per cent of its original size during the process. The researchers have tested the electrodes in the lab and in a working redox flow battery. However, scaling up the technology remains a challenge. “Scaling up is still a little bit limited because the 3D printing technologies that we use, they are not that scalable yet,” van der Heijden said. The researchers hope the technology could eventually help communities store renewable electricity and use it when it is needed, including in remote parts of Canada. “Have these flow batteries to make sure they can use this electricity whenever they want,” van der Heijden said. The team says taking inspiration from nature could help improve how renewable energy is stored and used.
