Agricultural waste streams usually end up in compost, animal feed, or energy production. Researchers at the University of the Basque Country have now described a different application. They produced anode material for sodium-ion batteries from sunflower husks, a waste stream that normally has little economic value. In trials with small button cell batteries, these cells continued to function for up to 1.000 charge and discharge cycles.
The study fits into the search for battery materials that are less dependent on scarce raw materials. Lithium-ion batteries still dominate the market, but require materials such as lithium, cobalt, and nickel. Sodium-ion batteries have long been considered an alternative, primarily because sodium is more widely available and cheaper than lithium. In this research, not only the choice of metal changes, but also the origin of the carbon material in the anode.
Comparison of biomass residue streams
The Basque research group compared several regional biomass residue streams as a basis for hard carbon. These included coffee grounds, corn cobs, grape seeds, grape skins, and compost. Of the streams studied, sunflower skins emerged as the best.
Performance and environmental impact
Following that selection, the researchers optimized the material and combined the anode with various cathode materials. Subsequently, they mapped not only the technical performance but also the environmental impact through a life cycle analysis. As a result, the research is not limited to capacity and lifespan but also addresses the material footprint of the battery system.
Still in the laboratory
The researchers themselves emphasize that this involves laboratory research. The button cells are not yet competitive with lithium-ion batteries and do not constitute a directly applicable industrial product. The researchers are now working on larger battery cells.
Source: University of the Basque Country, Producing rechargeable batteries using sunflower seed shells as raw material
Photo by Ksenia Pixelesse on Unsplash
