Closing the loop. Italian Waste biomass as a sustainable source for sodium‐ion battery anodes

Developing a sustainable circular economy requires specific protocols to produce sustainable energy materials for renewable energy deployment. Sodium-ion batteries (SIBs) offer a safer and cheaper alternative to lithium-ion batteries, but their performance is limited by anode materials. Here, we investigate hard carbons (HCs) derived from three Italian waste biomasses: hazelnut shells, wild giant cane, and olive stones, comparing them to commercially available petroleum-based HC. A facile and eco-friendly synthesis involving ball milling, citric acid digestion, and pyrolysis at 1100°C yields nanostructured active materials for SIBs. We analyze their morphology, porosity, microstructure, defectivity, surface chemistry, and electrochemical performance. Results reveal that the biomass-derived HCs exhibit comparable performance to the commercial counterpart. The wild giant cane and olive stone-derived HCs show the best electrochemical performance, offering a promising route toward sustainable and high-performance SIB anodes.