Electrochemical properties of Li2ZrO3-coated silicon/graphite/carbon composite as anode material for lithium ion batteries

Silicon/graphite/disordered carbon (Si/G/DC) is coated by Li2ZrO3 using Zr(NO3)(4)center dot 5H(2)O and CH3COOLi center dot 2H(2)O as coating reagents. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to characterize Li2ZrO3-coated Si/G/DC composite. The Li2ZrO3-coated Si/G/DC composite exhibits a high reversible capacity with no capacity fading from 2nd to 70th cycle, indicating its excellent cycleability when used as anode materials for lithium ion batteries. A compact and stable solid-electrolyte interphase (SEI) layer is formed on the surface of Li2ZrO3-coated Si/G/DC electrode. Analysis of electrochemical impedance spectra (EIS) shows that the resistance of the coated material exhibits less variation during cycling, which indicates the integrity of electrode structure is kept during cycling. XPS shows that F and P elements do not appear in the SEI layers of Li2ZrO3-coated Si/G/DC electrode, while they have a relatively high content in SEI layers of Si/G/DC electrode. The improvement of Li2ZrO3-coated Si/G/DC is attributed to the decrease of lithium insertion depth and the formation of stable SEI film. (C) 2008 Elsevier B.V. All rights reserved.