Designing hollowed carbon@Si cubic nanobox@reduced graphene oxide nanostructures for lithium-ion battery with high capacity and long cyclic stability

Abstract

In this work, we synthesized the hollowed carbon@Si cubic nanobox sandwiched by reduced graphene oxide (HC@Si@rGO) using the template-sacrificial method for lithium-ions batteries’ (LIBs’) anode with high specific capacity and ultra-stable long cyclic performance. During the preparation, the ZIF-8 was initially etched by Si(OH)4 to generate the hollowed ZIF-8 and instantaneously in-situ formation of SiO2 coatings on ZIF-8, resulting in synthesis of ZIF-8@SiO2. Afterwards, the ZIF-8@SiO2 was reduced to HC@Si by the magnesium thermal treatment while the NaCl was employed as a heat-removing agent. Successfully, the rGO was introduced coupling with HC@Si to obtain HC@Si@rGO. As anode for LIBs, it delivers high initial discharge capacity of 3712.9 mAh g[Formula: see text] at the current density of 0.1 A g[Formula: see text]. After 130 cycles, a stable specific capacity of 1311.0 mAh g[Formula: see text] is achieved. The long charge/discharge performance of HC@Si@rGO anode is demonstrated at 0.5 A g[Formula: see text], exhibiting the specific capacity of 595.4 mAh g[Formula: see text] after 500 cycles. Based on the electrochemical analysis, these remarkable performances are attributed to the unique nanostructure of HC@Si@rGO. Essentially, the inner-layered HC acts as a buffer matrix to reinforce the mechanical strength of the entire electrode and restrain the volume change of Si during the charge/discharge. On the other hand, the evenly distributed HC@Si is fixed within the flexible rGO sheets to form the network structure, which not only promises a good conductive connection between HC@Si but also prevents the continuous formation of solid electrolyte interface film.