Hard Carbon Derived from Spent Coffee Grounds for Applications in Sodium Ions Batteries

The manuscript investigates the use of spent coffee grounds (SCGs) as a precursor for the synthesis of hard carbon (HC) for sodium-ion batteries. The SCGs, provided by illycaffè S.p.A., are subjected to a two-step thermal process involving pyrolysis at 500 °C followed by carbonization at 1300 °C. The resulting hard carbon is characterized using techniques such as XRD, Raman spectroscopy and SEM, which revealed a significant increase in carbon content and the formation of porous particles. Electrochemical tests show that the coffee-derived hard carbon exhibited typical sodium storage behavior, with good capacity retention and high coulombic efficiency. This study demonstrates the potential of using waste coffee grounds for the sustainable production of electrode materials for sodium-ion batteries, highlighting a circular economy approach to battery production.