Turning waste silk into battery electrodes

carbonised silk

Waste silk textiles are showing enormous potential for creating cost-effective, sustainable high-density batteries, according to new research out of the Institute for Frontier Materials.

Issues of sustainability are becoming increasingly important for battery manufacturers in the face of dwindling lithium reserves.

However, Institute for Frontier Materials (IFM) researchers out of the ARC Training Centre in Future Energy Storage Technologies (StorEnergy), led by Dr Jenny Sun, are researching how waste materials, in particular waste silk textiles, could be used to replace standard electrodes used in lithium-ion batteries (LIBs), which require binders, conductive additives, and toxic solvents to prepare the electrode.

‘This is a big advantage,’ Dr Sun says. ‘It means we don’t need to use any additives, making them more cost-effective and sustainable.’

The researchers are testing the electrodes in sodium ion batteries (NIBs), which are a promising alternative for LIBs.

‘The great abundance of sodium makes them very price competitive,’ Dr Sun says. ‘And unlike LIBs, NIBs can be stored and transported safely in a fully discharged state.’

As they share a similar working chemistry with LIBs, NIBs can also be considered a drop-in technology for existing LIB battery manufacturing lines.

However, in order to expand their commercialisation, further electrode and electrolyte development is required. This project used an ionic liquid electrolyte earlier developed by storEnergy researchers.

This new finding has come off the back of other research out of IFM’s Fibres and Textiles group, led by Professor Xungai Wang, which had previously shown that a free-standing carbonised silk fabric can be prepared by a one-step heating process.

Dr Sun and her colleagues used samples of this material as electrodes in coin cells and tested their performance, including cycling and rate capability.

The electrode showed high-capacity retention (close to 100 per cent after 100 cycles) and initial coulombic efficiency of 75 per cent. This means the battery retains its capacity after being charged/discharged 100 times, and the capacity doesn’t decline.

The team, which hopes to seek industry opportunities with this research, is now working with Associate Professor Nolene Brown on other waste materials, such as cotton fibre, pitch and food waste as precursor materials for sodium ion batteries.

This is an edited version of this original article.