Abstract
A biobased anode material for sodium-ion batteries (SIBs) was prepared through the simple pyrolysis of Scotch pine cones (Pinus sylvestris, SPC), followed by a heteroatom doping modification. The resulting nitrogen-doped hard carbon exhibited a high reversible capacity of 273 mA·h·g(-1) at a current density of 25 mA·g(-1) compared to the undoped material (197 mA·h·g(-1)). X-ray diffraction analysis shows that the produced hard carbon from the biomass is highly amorphous in nature, and high-resolution transmission electron microscopy images reveal the presence of localized graphite-like structures that are found to be beneficial for the storage and transport of Na(+) ions during charging/discharging. Experimental results demonstrated that the increased specific surface area (S (BET) = 424 m(2)·g(-1)), high micropore volume (0.177 cm(3)·g(-1)), and expanded interlayer spacing (>3.7 Å) and a high Na(+)-ion diffusion coefficient (3.08 × 10(-16) cm(2)·s(-1)) facilitated the diffusion of sodium ions, leading to a high capacity retention of 80% after 250 cycles for the SPC-N material over the undoped one, SPC (71%). This study highlights the potential of low-cost, widely available biobased Scotch pine cones as an alternative anode material to enhance the sustainability of SIB production.