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Vast potential for silicon extraction from used solar panels to build better batteries


Aerial view of rows of solar panels in a field Photo: Adobe Stock
Scientists at Deakin University believe their new silicon reclamation process could generate $15bn in material recovery if extrapolated to the 78mn tonnes of solar panel waste expected to be generated globally by 2050

Photo: Adobe Stock

Researchers in Australia have developed a sustainable process to reclaim silicon from end-of-life solar panels and reconfigure it to build lithium-ion batteries with increased storage capacity.

More than 100,000 tonnes of end-of-life solar panels are estimated to enter Australia’s waste stream by 2035. However, scientists at Deakin University’s Institute for Frontier Materials (IFM) are reported to have successfully tested a new process that can extract silicon from old solar panels, then convert it into nano-silicon that can be mixed with graphite to develop a new type of battery anode shown to increase lithium-ion battery capacity by a factor of 10.


Lead researcher Dr Md Mokhlesur Rahman says that for Australia (and the world) to address the enormous issue of solar panel waste and develop a successful recycling programme to divert it away from landfill, scientists must find a way to harvest and repurpose the panels’ most valuable components.


‘Solar panel cells are fabricated using high-value silicon, but this material cannot be re-used without purification, as it becomes highly contaminated over the 25 to 30 years of the panel’s life,’ he explains. ‘We have developed a process that returns silicon collected from used cells to greater than 99% purity, within a day and without the need for dangerous chemicals. This thermal and chemical process is far greener, cheaper and more efficient than any other technique currently on the market.’


However, it is the next step that is the real game-changer, according to Rahman. The new process then takes this regular-sized purified silicon and reduces its size to nanoscale using a special ball-milling process. Again, without the need for toxic chemicals.


‘We are using that nano-silicon to develop low-cost battery materials that will help deliver the higher performing, longer lasting, affordable battery technology critically needed to drive Australia’s clean energy transition,’ he continues.


The current market price for nano-silicon is nearly 70 times that of regular silicon, and it is in even higher demand, according to the scientists. Not just for new battery materials, but also for use in the development of nano-fertilisers, innovative new methods for carbon capture, and on-demand hydrogen gas generation. By recycling solar panels, the IFM team has found a way to make this expensive material more accessible. They estimate their technique could generate $15bn in material recovery if extrapolated to the 78mn tonnes of solar panel waste expected to be generated globally by 2050.


The team is now talking with industry about plans to scale-up the process.