Neat Design for the Structure of Electrode to Optimize the Lithium Ion Battery Performance.

The appearance of mechanical cracks originated from anisotropic expansion and shrinkage of electrode particles during Li+ de/intercalation is a major cause of the capacity fading in Li-ion batteries. Well-designed and controlled nanostructures of electrodes have shown prominent prospect for solving this obstacle. Here we report a novel and convenient strategy for preparation of graphene nanoscroll wrapping Nb2O5 nanoparticles (denoted as T-Nb2O5/G). Firstly a high energy ball-milling is conducted to acquire softly-agglomerated T-Nb2O5 nanoparticles owing to its spontaneous reduction of surface energy among these single particles. Then freeze-drying leads to the formation of graphene nanoscroll, which easily realizes the in-situ wrapping over softly-agglomerated T-Nb2O5 nanoparticles. Extended cycling tests demonstrate that such T-Nb2O5/G yields a high reversible specific capacity of 222 mA h g-1 over 700 cycles at 1C. The dominated surface capacitive insertion processes possessing favorable kinetics enable the T-Nb2O5/G to exhibit excellent rate performance, which achieve capacity of 110 mA h g-1 at 10 C. A combined ex-situ XRD, SEM and TEM investigation reveal that the long-term cycling stability of T-Nb2O5/G is attributed to the excellent structural stability of electrode, in which the synergistic effect between the softly-agglomerated T-Nb2O5 nanoparticles and graphene nanoscroll prevents the formation of mechanical cracks.