The effect of ethyl cellulose coating on the surface of silicon–carbon composite as lithium anode material

Abstract

The silicon nanoparticles are loaded on the surface of graphite to prepare the silicon–carbon composite as lithium anode material. The first charge and discharge capacity of silicon–carbon composite is 644 and 739.6 mAh g−1, with the initial coulombic efficiency is 89.84%, and the capacity retention rate after 450 cycles is 65.23%. Moreover, the electrochemical performance of ethyl cellulose coated silicon–carbon composite has been investigated. The electrochemical kinetics performance such as charge transfer ability and lithium-ion diffusion are influenced by ethyl cellulose coating. However, the silicon nanoparticles were better bonded on the graphite carrier and less exposed on the surface after ethyl cellulose coating, which is benefit to decrease silicon nanoparticles split away from silicon–carbon composite and stabilize SEI film. Furthermore, the volume expansion is inhibited, so the cycle performance is obviously improved. The first reversible capacity of 5 wt% and 10 wt% ethyl cellulose coated silicon–carbon composite are 632.9 mAh g−1 and 593.3 mAh g−1 with capacity retention rate of 71.40% and 74.68% after 450 cycles, respectively.