Lath-shaped biomass derived hard carbon as anode materials with super rate capability for sodium-ion batteriesS

Biomass wastes or biomass derived hard carbon materials with the advantages of green, as well as economic and high reversible capacity have became the promising anode materials for sodium ion batteries (SIBs). Despite this, the poor rate capability hinders their further development. Here, we synthesized lath-shaped hard carbon materials derived from peanut shells by a two-step approach, namely a hydrothermal pretreatment for different treatment time first, and then a carbonized process at 800 degrees C. Morphology and structural characterizations (SEM, XRD and Raman) prove the hydrothermal pretreatment has a great influence on morphology transformation, the layer spacing, as well as the defect concentration which can enhance the adsorption sites of Na+ and shorten the transport route of sodium ions. The PSDHCs-4 (hydrothermal treatment for 4 h) electrode can deliver the highest reversible capacity of 256 +/- 5 mAh g(-1), and show the best capacity retention of 97 +/- 2% at the current rate of 0.1 C after 100 cycles. More importantly, PSDHCs-4 electrode shows the excellent rate performances with a reversible capacity of 261, 244, 206, 163, 125, and 100 mAh g(-1) at the current rates of 0.1, 0.2, 0.5, 1.0, 2.0 and 5.0 C, respectively. These remarkable electrochemical properties indicate that PSDHCs-4 material should be a promising anode material for SIBs.