Preparation of nano-sized hard carbon spherule and its electrochemical property

In this paper, Nano-sized hard carbon spherule (HCS) is prepared from the distilled water/ethylene glycol mixed solution by hydrothermal technique. Due to the addition of ethylene glycol, the as-prepared sample is a kind of nano-sized HCS and the particle size of nano-sized HCS is 50–100 nm. Furthermore, nano-sized HCS displays larger specific surface area attributed to the well-dispersed property. As a result, it shows lower charge transfer impedance than that of micro-sized HCS owing to the huge contact area between particles and electrolyte. However, the initial coulombic efficiency of nano-sized HCS is a little lower than that of micro-sized HCS due to the large specific surface area for electrolyte irreversible decomposition. Charge-discharge cycling tests demonstrate that nano-sized HCS samples have high capacity retention ratio (92.7%) and high reversible lithium storage performance (525 mA h g−1). Therefore, it is a potential anode material for lithium–ion batteries.

Graphical abstractNano-sized hard carbon spherule (HCS) is prepared from the distilled water/ethylene glycol mixed solution by a simple hydrothermal technique. Due to the addition of ethylene glycol, the as-prepared sample is a kind of nano-sized HCS with particle size between 50 and 100 nm. Besides, charge-discharge cycling tests demonstrate that nano-sized HCS shows high capacity retention ratio and high reversible lithium storage performance. Therefore, it is a potential anode material for lithium-ion batteries.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Nano-sized hard carbon spherule is prepared by hydrothermal technique. ► Nano-sized hard carbon spherule shows high reversible lithium storage capacity. ► Nano-sized hard carbon spherule is a promising anode candidate material.