Highly Porous Si Nanoframeworks Stabilized in TiO2 Shells and Enlaced by Graphene Nanoribbons for Superior Lithium-Ion Storage

To enhance the rate capability and cycling stability of Si-based materials in lithium-ion batteries, three-dimensional graphene nanoribbons (GNRs) enlacing Si@TiO2 nanoparticles are synthesized by magnesiothermic reduction, sol-gel and electrostatic adsorption processes. The rigid clamping layer of TiO2 on the surface of Si prevents the whole electrode from undergoing volumetric variation. GNRs act as bridges to interconnect the adjacent Si@TiO2 nanoparticles to form a successively conductive network with decreased inner resistance. Moreover, the effect of two other kinds of carbon resources (polydopamine and resorcinol formaldehyde) on the electrochemical performance of Si@TiO2 are also discussed. The Si@TiO2@GNRs composite shows an enhanced discharge capacity of 1295 mAhg(-1) at a current density of 0.5 Ag-1 in the 300th cycle and achieve an outstanding rate capacity of 689.3 mAhg(-1) even at 10.0 Ag-1. The design of the double protecting structure provides an alternative strategy to enhance the electrochemical performance of M-based materials (M=Si, Sn, and Ge).