Improved rate capability of lithium-ion batteries with Ag nanoparticles deposited onto silicon/carbon composite microspheres as an anode material

Ag-deposited silicon/carbon (Ag/Si/C) composite microspheres were synthesized and evaluated as an anode material for lithium-ion batteries (LIBs). The Si/poly(AN-co-TMSPM) composite microspheres were prepared through suspension 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/carbon (Si/C) composite microspheres even after heat treatment at high temperatures. The 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 to that of the Si/C composite electrodes using electrochemical impedance spectroscopy, constant current charging and discharging, and cycling performance at various cycling rates. The Ag/Si/C composite microspheres exhibited a higher specific capacity and better rate capability at the various current rates from C/10 to 5C than those of the 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 contributes to the charge-transfer kinetics of the Si/C composite electrode.

► Si/C composite microspheres were prepared by solution polymerization. ► Ag nanoparticles are evenly decorated onto the surface of Si/C microspheres. ► Ag/Si/C composite electrode shows higher capacity and improved rate capability. ► Ag nanoparticles decrease contact resistance between particles and electrolyte.