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Upcycled pure silicon used to create
lithium-ion batteries
After extracting high-purity silicon from expired solar panels, scientists upcycled it into ahigh-performing lithium-ion battery anode.

Shubhangi Dua
Created: Sep 08, 2023 01:33 PM ESTSCIENCE

Lithium-ion batteries need for EVs successfully manufactured using upcycled silicon
NTU / Youtube

Technology has rapidly progressed in the last few decades; however, especiallyin light of the climate crisis, maintaining its efficiency has proven difficult. Evensolar panels have a limited lifespan of just 30 years, implying that 78 million
tonnes of solar panels are due to expire by 2050.
Scientists from the Nanyang Technological University, Singapore (NTUSingapore) have come up with an efficient method to recover high-purity siliconfrom expired solar panels, enabling them to produce lithium-ion batteries.

htps://interes�ngengineering.com/science/upcycled-pure-silicon-lithium-ion-bateriesThis breakthrough could help meet the increasing global demand to powerelectric vehicles, said a statement by the scientists.

Recovering pure silicon from old solar panels
The study aimed to upcycle the silicon in solar panels that are usually discarded
after 25 to 30 years due to old age or becoming non-functional. However,engineers find it challenging to separate the pure silicon from other parts of thepanel, such as aluminum, copper, silver, lead, and plastic.

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The silicon produced from those parts is of insufficient quality; thus, a solution
was devised to recycle old solar panels safely.
The researchers developed an extraction method using phosphoric acid – asubstance commonly used in the food and beverage industry. They recorded ahigher recovery rate and purity than the current recovery methods.
Currently, scientists utilize high-purity silicon from old panels, but the process isenergy-intensive, expensive, and, most of all, unsafe as it requires the use oftoxic chemicals. The current formula limits recycling opportunities.
Nripan Mathews, Associate Professor, Provost’s Chair in Materials Science andEngineering, and Cluster Director of the Energy Research Institute, stated:“Our approach to silicon recovery is both efficient and effective. We do not haveto use multiple chemicals, reducing the time spent on post-treatment of thechemical wastes. At the same time, we achieved a high recovery rate of puresilicon comparable to those produced by energy-intensive extraction
techniques.”htps://interes�ngengineering.com/science/upcycled-pure-silicon-lithium-ion-bateries

As the new method maintains the resources in a loop, researchers believe that it
has the potential to solve the growing problem of solar panel waste.

Silicon essential for EVs
Silicon is a substantial material that helps manufacture the next-generation
lithium-ion batteries. These batteries power electric vehicles (EVs) as thetechnology allows the vehicles an extended range and fast charging times.
The innovators believe that their upcycled development will be able to support
the expected demand for high-purity silicon.
The process of manufacturing the silicon for advanced EVs involves soaking
expired solar cells in hot diluted phosphoric acid for 30 minutes.
After which, the metals – aluminum and silver – are removed from the surface.
This is repeated using phosphoric acid until the metals are completely
separated, which results in the production of pure silicon.
The statement by the researchers explains that advanced spectroscopic wasdeployed to evaluate the elemental content of the recovered wafer. The devised
sample achieved a recovery rate of 98.9 percent with a purity of 99.2 percent.
As a consequence, the recovered silicon, when upcycled into a lithium-ion
battery anode, performed as well as a brand new commercially purchased
silicon.
Watch the scientists explain how they recovered silicon from expired solar
panels below:
Dr. Sim Ying, Research Fellow, Energy Research Institute, stated:“The comparable performance between our upcycled silicon-based lithium-ion
battery and the newly purchased ones proves that the NTU approach is feasible.
We envision our faster and cheaper silicon recovery method to be a positive
boost for the development of EV batteries. Aside from EVs, there are also
potential applications such as thermoelectric devices.”
The team of scientists submitted a technology disclosure to NTUitive – NTU'sinnovation and business organization. This step sets the stage for possiblecommercialization of the silicon recovery method. Simultaneously, theresearchers are actively looking for industry partners to investigate potential
market uses.

htps://interes�ngengineering.com/science/upcycled-pure-silicon-lithium-ion-bateries

The initiative is integrated into the Singapore-CEA Alliance for Research in
Circular Economy (SCARCE) program, a collaboration between NTU and theFrench Alternative Energies and Atomic Energy Commission.
The study was published in the scientific journal Solar Energy Materials and SolarCells.