Insight into the Self-Assembled Three-Dimensional Sandwich-Like Hollow Silicon Nanoarray/Graphene Lithium Storage Architecture by Sonication-Assisted Functionalization

A three-dimensional (3D) sandwich-like hollow silicon nanoarray/graphene (hollow-Si-nanoarray/graphene) architecture was designed and constructed for high-performance lithium storage materials by sonication-assisted functionalization in 20 min. The architecture and morphology of the as-prepared samples are characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. The results show that the graphene sheets create strong bonds of functional groups, which attach firmly to both the surface of hollow silicon nanorods (hollow-Si-nanorods) and in situ formed polyaniline, which, in turn, glue to both the graphene sheets and hollow-Si-nanorods inside this unique nanoarchitecture. The as-prepared hollow-Si-nanoarray/graphene electrode exhibits excellent electrochemical performance, delivering reversible capacities of over 1200 mAh g(-1) at 0.2 C, 900 mAh g(-1) at 2 C, and 700 mAh g(-1) at 5 C with capacity retention rates over 88%, even after 500 cycles. This excellent electrochemical performance arises from the very stable 3D sandwich-like nanoarchitecture with high tensile strength and high flexibility, the efficient accommodation for the volume change of hollow silicon nanorods during discharge/charge, and the efficient transportation of both the electrons through the sustainable continuous good electronically conductive networks and the lithium ion through the ordered mesoporous pathways throughout the electrode. This unique material design and the concept of the facile in situ construction are expected to be practically applicable to develop Si-based anodes for next-generation lithium-ion batteries.