A new type of electrode may help researchers finally solve one of the challenges preventing solar power from becoming a total energy solution.

RMIT University researchers believe a new graphene-based prototype— which is inspired by the structure of fern leaves— could boost the capacity of existing integrable storage by 3,000 percent and open a new path to the development of flexible thin film all-in-one solar capture and storage.

This advancement may lead to self-powering smart phones, laptops, cars and buildings.

The electrode is designed to work with supercapacitors, which can charge and discharge power significantly faster than conventional batteries. Supercapacitors have been combined with solar in the past, but their wider use as a storage solution is restricted because of their limited capacity.

The fractal design reflected the self-repeating shape of the veins of the western swordfern—Polystichum munitum—native to western North America.

RMIT’s Professor Min Gu explained how the prototype is based on the fern leaves.

“The leaves of the western swordfern are densely crammed with veins, making them extremely efficient for storing energy and transporting water around the plant,” Gu, the leader of the Laboratory of Artificial Intelligence Nanophotonics and associate deputy vice-chancellor for Research Innovation and Entrepreneurship at RMIT, said in a statement.

Gu explained that the electrode is based on self-replicating fractal shapes and the researchers used the 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,” Gu said. “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.”

Solar energy storage is an emerging technology that can promote the solar energy as the primary source of electricity. Recent developments of laser scribed graphene electrodes exhibiting a high electrical conductivity have enabled a green technology platform for supercapacitor-based energy storage, resulting in cost-effective, environment-friendly features and consequent readiness for on-chip integration.

According to the study, the new conceptual design removes the limit of the conventional planar supercapacitors by significantly increasing the ratio of active surface area to volume of the new electrodes and reducing the electrolyte ionic path.

The researchers combined the fractal-enabled laser-reduced graphene electrodes with supercapacitors to hold the stored charge for longer with minimal leakage.

Ph.D. researcher Litty Thekkekara explained that there are many applications for the prototype.

 “Flexible thin film solar could be used almost anywhere you can imagine, from building windows to car panels, smart phones to smart watches. We would no longer need batteries to charge our phones or charging stations for our hybrid cars. With this flexible electrode prototype we’ve solved the storage part of the challenge, as well as shown how they can work with solar cells without affecting performance,” she said.  

“Now the focus needs to be on flexible solar energy, so we can work towards achieving our vision of fully solar-reliant, self-powering electronics.”

The study was published in Scientific Reports.