3, University of California, Riverside, Riverside, California, United States
2, University of California, Riverside, Riverside, California, United States
Silicon is considered as one of promising electrode materials for lithium-ion batteries (LIBs), thanks to its high energy density, high theoretical specific capacity and low discharge potential. Note that the strong volume expansion (~300%) of silicon during lithiation and delithiation is one of the main issues for its applications. To solve this issue, we develop silicon-carbon nanospheres (SCNSs) as LIB anodes by a simple and scalable method. Firstly, silicon nanospheres (SNSs) are synthesized via magnesium reduction of silica nanospheres, which are produced by an in-situ acid catalyzed polymerization of tetraethyl orthosilicate (TEOS). The SNSs with 3D nanoporous spheres have an average diameter of ~100 nm. To fully extract the real performance of the SNSs, carbon coating is further performed to enhance the electronic conductivity of SNSs. We obtain the SCNSs LIB anodes exhibiting excellent lithium storage performance, which have a reversible capacity of ~3170 mAh g−1, high rate capability (C/2) and cyclic stability (capacity of ~1010 mAh g-1 after 500 cycles). Our results demonstrate that the spherical nature and high nanoporosity of the SCNSs significantly improves the electrochemical stability by accommodating the volume changing.