The new graphene-based electrode can be combined with a solar cell for on-chip energy harvesting and storage. It could boost the capacity of existing storage technologies by 3000 per cent and could also open a new path to the development of flexible thin film all-in-one solar capture and storage, bringing the world one step closer to self-powering smart phones, laptops, cars and buildings. The electrode is designed to work with supercapacitors which can charge and discharge power much faster than conventional batteries. Supercapacitors have been combined with solar, but their wider use as a storage solution is restricted because of their limited capacity.
The researchers were inspired by an American fern, the western swordfern, Polystichum munitum, native to western North America. RMIT’s Professor Min Gu said the new design drew on nature’s own genius solution to the challenge of filling a space in the most efficient way possible – through intricate self-repeating patterns known as “fractals”. Combined with supercapacitors, the fractal-enabled laser-reduced graphene electrodes can hold the stored charge for longer, with minimal leakage.
“The leaves of the western swordfern are densely crammed with veins, making them extremely efficient for storing energy and transporting water around the plant” said Gu, Leader of the Laboratory of Artificial Intelligence Nanophotonics and Associate Deputy Vice-Chancellor for Research Innovation and Entrepreneurship at RMIT. “Our electrode is based on these fractal shapes – which are self-replicating, like the mini structures within snowflakes – and we’ve used this naturally-efficient design to improve solar energy storage at a nano level. The immediate application is combining this electrode with supercapacitors, as our experiments have shown our prototype can radically increase their storage capacity – 30 times more than current capacity limits. Capacity-boosted supercapacitors would offer both long-term reliability and quick-burst energy release - for when someone wants to use solar energy on a cloudy day for example - making them ideal alternatives for solar power storage.”
Lead author, PhD researcher Litty Thekkekara, added that because the prototype was based on flexible thin film technology, its potential applications were countless. The most exciting possibility is using this electrode with a solar cell, to provide a total on-chip energy harvesting and storage solution. It is possible to do that now with existing solar cells but they are bulky and rigid. The real future lies in integrating the prototype with flexible thin film solar – technology that is still in its infancy. Flexible thin film solar could be used almost anywhere you can imagine, from building windows to car panels, smart phones to smart watches. The world would no longer need batteries to charge phones or charging stations for hybrid cars.
With this flexible electrode prototype the researchers say they’ve solved the storage part of the challenge, as well as shown how they can work with solar cells without affecting performance. Now the focus needs to be on flexible solar energy, so they can work towards achieving their vision of fully solar-reliant, self-powering electronics.
Image: RMIT University
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