Published on 13 Sep 2023

Upcycling Silicon from Expired Solar Panels for Lithium-ion Batteries - Assoc Prof Nripan Mathews

We are delighted to share that Associate Professor Nripan Mathews, Cluster Director (Solar Energy & Solar Fuel) of ERI@N, and his team have been featured in various media platforms for their research on recycling high-purity silicon from expired solar panels to produce lithium-ion batteries. 

Solar cell panels contain a significant amount of high-purity silicon, which is often discarded at the end of their 25 to 30-year lifespan. Separating silicon from other components like aluminium, copper, silver, lead, and plastic has proven to be a challenging task. Furthermore, recycled silicon is often poor quality and unsuitable for other silicon-based technologies. Current methods of recovering high-purity silicon are energy-intensive and rely on toxic chemicals, making them costly and unfeasible for widespread adoption amongst recyclers.

To overcome these challenges, Associate Professor Nripan Mathews and his team devised a sustainable and innovative method of extracting high-purity silicon using phosphoric acid, which is a commonly used substance in the food and beverage industry. Their approach not only achieves a higher recovery rate and purity compared to current technologies but also simplifies the process by using just one reagent (e.g. phosphoric acid), as opposed to multiple highly acidic/alkaline chemicals used in conventional methods. 

"Our approach to silicon recovery is both efficient and effective. We do not have to use multiple chemicals, reducing the time spent on post-treatment of the chemical wastes. At the same time, we achieved a high recovery rate of pure silicon comparable to those produced by energy-intensive extraction techniques."
- Associate Professor Nripan Mathews – 
From left: Dr Ankit (back), Lead Author of the study - Dr Sim Ying (front), Associate Professor Nripan Mathews (front) and Dr Tay Yeow Boon (back). (Source: NTU)

The team's work has been published in the peer-reviewed journal - Solar Energy Materials and Solar Cells - under the title “Simplified Silicon Recovery from Photovoltaic Waste Enables High Performance, Sustainable Lithium-ion Batteries". (DOI:

Their study highlights NTU’s commitment to sustainability and innovation for a circular economy under the 2025 Strategic Plan. It also aligns with the NTU Sustainability Manifesto, which guides the University towards sustainability, carbon neutrality, and societal impact. The project is also part of the Singapore-CEA Alliance for Research in Circular Economy (SCARCE) programme.

For the full media release, please visit the following link: Upcycling silicon from expired solar panels into lithium-ion batteries | NTU Singapore 

We extend our congratulations to Associate Professor Nripan Mathews and his team on this outstanding achievement!

Media Coverage: