Hard carbon derived from waste tea biomass as high-performance anode material for sodium-ion batteries

Sodium-ion batteries (SIBs) with the advantage of low cost are attracting tremendous attention in large-scale practical application because of the abundance of Na resources. Nevertheless, the anode is still a great challenge in the development of SIBs. Herein, hard carbon derived from an abundant biomass of waste tea was prepared by a simple carbonization method. Meanwhile, the correlation between pyrolysis temperature and microstructure and the electrochemical properties of the as-prepared carbon materials were studied in details. The results indicate that the plateau capacity of these anode materials is closely related to carbonation temperature. Notably, the hard carbon sample pyrolyzed at 1400 °C presents the highest reversible specific capacity of 282.4 mAh g−1 and good rate capability, as well as excellent cycling stability with capacity retention of 83% after 200 cycles. Such hard carbon with promising electrochemical properties provides the chance to develop the less expensive sodium anode materials.