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.