Introduction
Lithium-ion batteries (LIBs) as a kind of clean energy have been
intensively utilized in portable electronics and show significant
promise for the applications in hybrid electric vehicles (HEVs),
electric vehicles (EVs), and smart grids. Graphite is used as the
dominant anode in commercial LIBs, but its specific capacity is
limited to 1 mol Li per C6 (372 mAh g1). Besides, the Li
intercalation into graphite appears at a low potential which is
close to that of the Li-plating, which easily gives rise to the short
circuit of batteries due to the formation of Li dendrites [1]. All these
issues related to graphite limit its application in the future, so,
further improvements in terms of energy power, densities, cycle
time and safety are required. Meanwhile, the rapid development of
nanoscience and nanotechnology has greatly motivated the
scientific community and industry to explore new features of
both typical and novel materials at the nanoscale level currently.
Since the discovery of carbon nanotubes [2], it has been widely