Synthesis of a pomegranate shaped reduced graphene oxide stabilized secondary Si nanoparticles composite anode for lithium ion batteries

Abstract A 3D porous micro-size pomegranate shaped nano-silicon and reduced graphene oxide composite (Si/RGO-S) is synthesized in this work by spray drying and magnesiothermic reduction treatments of silicon dioxides (SiO2) nanospheres and few-layered graphene oxide sheets (GO). The SiO2 nanospheres convert to smaller Si secondary nanocrystals and GO sheets are deoxygenated to form a supporting RGO framework, respectively. Favorable void space is created between the secondary Si nanoparticles for the accommodation of the volume changes during lithium ion storage. The 3D porous RGO protecting skeleton not only improves the overall electronic and ionic conductivity, but also effectively immobilizes the inside Si nanoparticles. Under a current density of 500 mA g−1, the 3D Si/RGO-S composite exhibits a reversible capacity of 1200 mAh g−1 for 300 consecutive cycles, which is much higher than the controlled 2D sample (Si/RGO-F) prepared by a freeze drying and magnesiothermic reduction method as anode material for lithium ion batteries. The insight into the superior lithium ion storage performance of the Si/RGO-S has been given in this work.