SnO₂-graphene-carbon nanotube mixture for anode material with improved rate capacities

SnO₂-graphene-carbon nanotube (SnO₂-G-CNT) mixture is synthesized using graphene oxide as precursor for application as anode material in rechargeable Li ion batteries. It is shown that the SnO₂ nanoparticles of 3-6 nm in diameter are not only attached onto the surface of graphene sheets by anchoring with surface functional groups, but they also are encapsulated in pore channels formed by entangled graphene sheets. The incorporation of carbon nanotubes reduces the charge transfer resistance of the anode made from the mixture through the formation of 3D electronic conductive networks. The SnO₂-G-CNT anodes deliver remarkable capacities of 345 and 635 mAh g^-1 at 1.5 and 0.25 A g^-1, respectively. Flexible electrodes consisting of highly-aligned SnO₂-G-CNT papers are also prepared using a simple vacuum filtration technique. They present a stable capacity of 387 mAh g^-1 at 0.1 A g^-1 after 50 cycles through the synergy of the high specific capacity of SnO₂ nanoparticles and the excellent cycleability of G-CNT paper.