Silver nanoparticles doped silicon/carbon composite microspheres as an anode material with enhanced rate capability in lithium-ion batteries

Abstract

Ag-deposited silicon/carbon (Ag/Si/C) composite microspheres were synthesized and evaluated as an anode material for lithium-ion batteries (LIBs). Si/poly(AN-co-TMSPM) composite microspheres were prepared through solution polymerization and were decorated with Ag nanoparticles by a wet chemical method in an aqueous AgNO3 solution. Ag nanoparticles remained on the surface of the Si/C composite microspheres even after heat treatment at high temperature. Si/C and Ag/Si/C composite microspheres were characterized by scanning electron microscopy, focused ion beam-scanning electron microscopy, and X-ray diffraction. The electrochemical performance of the Ag/Si/C composite electrode was compared with that of the Si/C composite electrodes using electrochemical impedance spectroscopy, cycle life tests using constant current charging and discharging, and cycling performances at various current densities. Ag/Si/C composite electrode exhibited a higher specific capacity and better rate capability at the various current rates from 0.1 C to 5 C than those of Si/C composite electrode without Ag nanoparticles when they were used as the anode material in LIBs. These results suggest that the surface deposition with Ag nanoparticles forms a conductive solid electrolyte interphase (SEI) layer after the formation cycling, which contributes to charge-transfer kinetics of the Si/C composite electrode.