Abstract
In this study, we introduce a straightforward and effective approach to produce P-doped hard carbon using coffee grounds as the precursor, with H3PO4 serving as the doping agent. By varying the concentrations of H3PO4 (1M, 2M, and 3M), we aimed to determine the optimal doping level for maximizing the incorporation of phosphorus ions into the carbon framework. Our investigation revealed that using 2M of H3PO4 as the dopant material for hard carbon led to promising electrochemical performance when employed as an anode material for sodium-ion batteries. The P-doped hard carbon, carbonized at 1300 °C, exhibited an impressive reversible capacity of 341 mAh g-1 at a current density of 20 mA g-1, with an initial Coulombic efficiency (ICE) of 83%. This outstanding electrochemical performance of P-doped hard carbon can be attributed to its unique properties, including a porous agglomerated structure, a significant interlayer spacing, and the formation of C-P bonds.