From food waste to high-capacity hard carbon for rechargeable sodium-ion batteries

In this study,we introduce a straightforward and effective approach to produce P-doped hard carbon using coffee grounds as the precursor,with H_(3)PO_(4)serving as the doping agent.By varying the concentrations of H_(3)PO_(4)(1 M,2 M,and 3 M),we aimed to determine the optimal doping level for maximizing the incorporation of phosphorus ions into the carbon framework.Our investigation revealed that using 2 M of H_(3)PO_(4)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℃,exhibited an impressive reversible capacity of 341 mAh g1 at a current density of 20 mA g1,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.