Branched Graphene Nanocapsules for Anode Material\nof Lithium-Ion Batteries

Abstract

The\npromising complex structures of graphene nanocapsules with <i>in situ</i> formed graphene sheets (GC-Gs) have been generated\nby partially peeling the multiwalled graphene capsules (MWGCs) with\na small size of ca. 15 nm. The abundant edges and defects on the <i>in situ</i> induced graphene sheets and capsule walls largely\nfavored the lithiation/delithiation reaction and resulted in a high\nLi-ion storage level. Since the surface area loss of GC-Gs during\nstacking and aggregation is generally avoided due to the branched\nstructures and the active doping atoms (N, S) can be intercalated\ninto the carbon\nlattices during sample preparation, the unique GC-Gs possess an excellent\nreversible capacity of 1373 mAh g^–1 at 0.5 A g^–1 as anode material in lithium-ion batteries. This\nvalue is more than 3 times that of the theoretical capacity of state-of-the-art\ngraphite counterpart, and higher than those of most carbon materials\nreported to date and even the composites of metal, alloys with carbon\nmaterials.