Recycling silicon from PV panels for making advanced lithium ion batteries

The outcome

The research project’s purpose was to recover silicon from end-of-life photovoltaic (PV) panels. This involved developing an environmentally friendly process to remove impurities from the recycled silicon and convert it to nano silicon - a high value commodity for electronic industries and energy storage in batteries.

As well as purification process, the research also explored a nano silicon graphite hybrid formation for lithium-ion battery applications. The nano silicon derived from recycled silicon was found to have properties comparable with commercially available, highly expensive nano silicon (valued at approximately US $36,000 per kg).

The research also discovered that end-of-life PV recycled silicon was an excellent material to produce high performance silicon-graphite hybrid anode for lithium-ion batteries (a type of rechargeable battery that uses lithium ions to generate power required by electronic devices).

This project successfully demonstrated that recycled silicon from end-of-life PV panels can be processed in an environmentally sound manner to produce high value nano silicon. The results obtained from the lithium-ion batteries developed using the nano silicon/graphite anode also show great promise for future battery development, a new sustainable process for extraction, and groundbreaking next generation battery performance.

The need

End-of-life PV panels (solar panels) are forecast to become one of the largest sources of e-waste globally. By 2050, it is estimated that worldwide PV waste will be around 78 million tonnes.

It is also estimated that more than 100,000 tonnes of PV panels will enter Australia’s waste stream by 2035. This has the potential to create a hazardous waste management issue, materials including lead, cadmium, selenium, barium, phosphorous, and boron are dopants that can leach into soil and groundwater, causing environmental contamination and safety concerns if managed poorly. Victoria has banned the disposal of PV panels to landfill due to these serious environmental hazards.

Many companies are working to develop a process for separating the layers of raw materials in PV panels. The research project aimed to advance the recycling processes of PV panels and as a result, the value of the recycled material is maximised.

Developing the solution

The research involved creating a technique to convert PV recycled silicon (free of impurities) to nano silicon and subsequent nano silicon/graphite anode for battery application. The project involved:

• purification process and process validation by implementing a wide range of characterisation techniques
• analysis techniques for identifying critical properties including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), high resolution TEM, high angle annular dark-field (HAADF) scanning transmission electron microscopy, atomic force microscopy (AFM), surface area measurements, and Raman spectroscopy
• slurry preparation, electrode fabrication (commercial nano silicon, graphite, PV nano silicon and PV nano silicon/graphite), electrode drying-cutting-weighing, and coin-cell fabrication
• battery performance evaluation by adopting a wide range of electrochemical workstations (Solartron, Ivium, and land battery testing system)
• evaluation of electrochemical performances including galvanostatic charge/discharge, cycling stability, rate capability, Coulombic efficiency, and impedance spectroscopy in lithium-ion batteries
• data analysis and manuscript preparation for publication.

The research suggests end-of-life PV recycled silicon can be a sustainable source of distinct nano silicon to create next generation nano silicon/graphite anodes, potentially providing a breakthrough in lithium-ion battery performance.

The partnership

Deakin University was the project lead and worked with Delaminating Resources and Close the Loop.

Delaminating Resources has taken a pioneering initiative to recover silicon from discarded PV panels and the company supplied these materials to the research project.

Close the Loop worked closely with Delaminating Resources in parallel with this project to assess the logistics and economic feasibility for solar panel recycling.

Pathway to commercialisation

Companies have shown significant interest in the proof of concept outcomes and Deakin is currently exploring commercial opportunities. This project has potential for a pilot facility located and operated in regional Victoria, and ultimately could create a new industry for regional Victoria as well as new jobs.

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