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This work reports the growth of graphene nanobuds (GNB) on Cu foil by chemical vapor deposition and its direct application as an electrode in lithium-ion batteries. The obtained novel GNB anode exhibited a superhigh specific capacity of 2813 mAh g−1 at a current rate of 4 A g−1 with a reversible coulombic efficiency of 78% in the first cycle. The most important advantage of using GNB as an anode was its outstanding cycled performance, maintaining a stable capacity of 1600 mAh g−1 at 8 A g−1 for at least 330 charge/discharge cycles with a coulombic efficiency of 99%. More significantly, the cell still maintained a retention capacity of 870 mAh g−1 when cycled at the very high current rate of 40 A g−1. The exceptional electrochemical performance in storage capacity and rate capability of GNB can be mainly attributed to the nanobuds having more loose space in their adjacent walls and hollow spaces; and to the intrinsic nano-oriented structure of few-layered graphene. This unique structure enables better Li-ion diffusion and higher Li-ion storage capacity. The outstanding electrochemical performance of the GNB as an anode places it as one of the most promising advanced carbon materials for next-generation lithium-ion batteries. [Display omitted] • A new material assembly approach on graphene nanobuds for advanced Li-ion batteries. • Graphene nanobuds with exceptional energy storage using a novel anode design paradigm. • Graphene nanobuds exhibited a relatively high efficiency and good reversibility. • The semifullerenes-graphene network enhances the diffusion and storage of Li-ion. • Direct deposit of GNB on the electrodes improves the electrical conductivity. [ABSTRACT FROM AUTHOR]

Zero-strain and long-term stability of nanoscale lithium titanate (LTO) anode materials make possible the fabrication of exceptionally stable lithium ion batteries. But one issue must be considered that of nanostructure-induced relaxation in 2D LTO nanosheets which profoundly modifies their Li storage properties and structural stability. Excessively intercalated Li ions at both 8 a and 16 c sites trigger nucleation of the relaxed LTO structure in the near-surface region, which impedes Li-ion diffusion and causes the increasing polarization of LTO nanosheet electrodes. Nuclei of relaxed LTO then undergo isotropic growth along the 3D Li-ion pathways in LTO to completely convert near-surface regions into relaxed LTO. With increasing population of trapped Li ions, the enhanced conductivity due to Ti4+/Ti3+ reduction gradually eliminates the raised polarization. In the meantime, spontaneous electrolyte/LTO reduction to form the solid electrolyte interphase starts playing a major role in capacity loss once the transformation of near-surface region into relaxed LTO becomes saturated. Elucidation of these fundamental intercalation-induced surface structure transformations contribute greatly into the design of highly performing 2D nanoscaled LTO and other electrode materials. [ABSTRACT FROM AUTHOR]