Directing silicon-graphene self-assembly as a core/shell anode for high-performance lithium-ion batteries.

There is great interest in utilization of silicon-containing nanostructures as anode materials for lithium-ion batteries but usually limited by manufacturing cost, their intrinsic low electric conductivity, and large volume changes during cycling. Here we present a facile process to fabricate graphene-wrapped silicon nanowires (GNS@Si NWs) directed by electrostatic self-assembly. The highly conductive and mechanical flexible graphene could partially accommodate the large volume change associated with the conversion reaction and also contributed to the enhanced electronic conductivity. The as-prepared GNS@Si NWs delivered a reversible capacity of 1648 mAh·g(-1) with an initial Coulombic efficiency as high as 80%. Moreover, capacity remained 1335 mAh·g(-1) after 80 cycles at a current of 200 mA·g(-1), showing significantly improved electrochemical performance in terms of rate capability and cycling performance.