Theoretical Study of sp²-sp³ Hybridized Carbon Network for Li-ion Battery Anode

We discover through first-principles calculations a new type of nanoporous carbon network structure formed out of small diameter nanotubes that features unique sp2-sp3 bonding hybridizations and highly ordered 1-D channels for Li-ion diffusion. Unlike other graphitic materials that are primarily bonded by intertube/interlayer van der Waals forces, the predicted sp2-sp3 hybridized carbon networks (HCNs) are held together by strong sp3 covalent bonding at the junctions, with sp2-hybridized interconnects providing conducting π-electrons near the Fermi level. With well-aligned and size-tunable 1-D nanopores, we show that besides desirable high Li capacity, stable Li-ion intercalation voltage profile, and low diffusion barriers, the volumetric change of HCN between fully lithiated/delithiated phases is <1%, making it a very promising Li-ion battery anode candidate.