Hard carbons derived from waste tea bag powder as anodes for sodium ion battery

Abstract

In recent years, biomass-basedhard carbons have become main interest in sodium battery research community because of the abundant availability, cheap and excellent electrochemical performance. Here, hard carbons derived from waste tea bag powder have been prepared by hydrothermal carbonization and then followed by the physical activation. The hard carbons possessed sheet-likestructures which contained sufficient mesopore and micropore structures to assist the sodium ion transport and electrolyte penetration. The interlayer spacing of the obtained hard carbons is larger than that of graphite which can allow the insertion/extraction of sodium ions during charge-dischargeprocess. When utilized as anodes for sodium ion batteries, the hard carbons performed stable cycle profiles, maintaining aspecific capacity of 193 mAhg(-1)until the100(th)cycle at a current density of 100 mAg(-1)and capacity of 127 mAhg(-1)after 200 cycles under acurrent density of 1000 mAg(-1).