Researchers develop solar panel recycling solution

Researchers from Deakin University’s Institute for Frontier Materials have found a way to extract silicon from discarded solar panels and repurpose it into nano-silicon for batteries, potentially eliminating the biggest barrier to photovoltaic cell recycling.

Material scientists Mokhlesur Rahman and Ying Chen, who lead the investigation, said silicon recovery is to key to repurposing discarded solar cells and will prevent the high-value waste from going to landfill.

“Although silicon semiconductors make up a relatively small part of solar panel cells, the material’s value is extremely high. Scientists have been looking for ways to repurpose the silicon for some time, and we believe this to be the missing piece of the puzzle,” Dr Rahman said.

According to the researchers, the average service life of a solar panel is between 15 to 25 years, with modelling suggesting that without silicon recycling there will be 1.5 million tonnes of solar panel waste in landfill by 2050.

“Silicon cells are the most important component of a solar panel, transferring the sun’s energy into electrons.  They’re also a high-value material being a chemical element and far too precious to end up as waste, which is why this finding is significant,” Prof Chen said.

“We can’t claim solar panels to be recyclable, in a circular economy sense, until scientists find a way to harvest and repurpose their most valuable components.”

According to Dr Rahman, repurposed silicon can be used to make high-energy anodes, the transporters that move electrons around inside a battery.

“Surprisingly, the recovered silicon seems to work the same way as commercial silicon does,” Dr Rahman said.

“Our preliminary investigation validates the concept of disassembling silicon-based photovoltaic panels, and repurposing the existing silicon into nano-silicon for the battery industry, creating huge potential as an alternative source for the sector.”

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Deakin researchers could recycle jeans into joints

Advanced textile recycling methods could see denim jeans transformed into artificial cartilage for joint reconstruction.

Deakin University researchers Dr Nolene Byrne and PhD candidate Beini Zeng have discovered how to dissolve denim and turn them into an aerogel that can be used for cartilage biosculpting, water filtration and used as a separator in advanced battery technology.

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Dr Byrne said the denim recycling technique would also help contribute to the fight against textile waste.

“Textile waste is a global challenge with significant environmental implications, and we’ve been working for more than four years to address this problem with a viable textile recycling solution,” she said.

“With population growth and the development of third world countries combined with today’s rapid fashion cycles, textile waste is always increasing, leading to millions of tonnes of clothes and other textiles being burnt or dumped in landfill.”

Dr Byrne said Deakin’s Institute for Frontier Materials team used an “upcycling” approach to get around cost-effectiveness issues.

“One of the main drawbacks of textile recycling efforts is that any advanced technique requires the use of chemicals, which can then make the procedure less cost-effective,” she said.

“We use environmentally-friendly chemicals, and by upcycling our approach to create a more advanced material we can address the limitations affecting other less cost-effective methods.

“We are now entering pilot-scale trials and look to be at commercial scale within 3 to 5 years with industry support.”

Dr Nolene Byrne (left) and PhD candidate Beini Zeng (right)

She said the process worked because denim was made from cotton, a natural polymer comprised of cellulose.

“Cellulose is a versatile renewable material, so we can use liquid solvents on waste denim to allow it to be dissolved and regenerated into an aerogel, or a variety of different forms,” she said.

“Aerogels are a class of advanced materials with very low density, sometimes referred to as ‘frozen smoke’ or ‘solid smoke’, and because of this low density they make excellent materials for bioscaffolding, absorption or filtration.

“When we reformed the cellulose, we got something we didn’t expect – an aerogel with a unique porous structure and nanoscopic tunnels running through the sample.”

Dr Byrne said she believed the sticky nature of the denim cellulose solution was likely responsible for the unique aerogel structure that resulted, something ideally suited for use as synthetic cartilage.

“That’s exactly what cartilage looks like – you can’t 3D print that material – and now we can shape and tune the aerogel to manipulate the size and distribution of the tunnels to make the ideal shape,” she said.

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