Turning waste silk into battery electrodes

storEnergy researchers have achieved exciting results with battery electrodes prepared from waste silk textiles. The new material shows outstanding performance, with potential for creating high-energy-density batteries, according to lead researcher, Dr Jenny Sun from Deakin University’s Institute for Frontier Materials.

Issues of sustainability are becoming increasingly important for battery manufacturers in the face of dwindling lithium reserves. However, new battery technologies must also be competitive in terms of performance and cost.

Unlike standard electrodes used in lithium ion batteries (LIBs), which require binders, conductive additives, and toxic solvents to prepare the electrode, the silk-based electrodes are free-standing. “This is a big advantage,” says Dr Sun. “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,” says Dr Sun. “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.

IFM textile researchers, led by Prof Xungai Wang, 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 is now working with A/Prof Nolene Brown on other waste materials, such as cotton fibre, pitch, food waste, etc as precursor materials for sodium ion batteries.

Ref: Sustainable free-standing electrode from biomass waste for sodium-ion batteries. Sun, J., Rakov, D., Wang, J., Hora, Y., Wang, X., Howlett, P.C., Forsyth, M., Laghaei, M., Byrne, N. ChemElectroChem, (2022) https://doi.org/10.1002/celc.202200382.