Preparation And Electrochemical Properties Of Silicon Carbon Composite Anode Materials For Lithium Ion Batteries

With the need of battery becomes more and more widely, energy density, cycling life and safety of the lithium ion battery are facing more strict requirements. Therefore, the development of lithium ion battery which has higher energy density, longer life, higher safety becomes quite urgent. Electrode material is the key factor to determine the performance of the lithium ion battery, so the development of new type electrode material has become the research focus of the lithium battery.Among the new anode materials, silicon stands out with its extremely high capacity and a wide range of sources. However, this anode material suffers from serious volumetric expansion and contraction during charge/discharge cycling, which cause rapid capacity fading due to deterioration in electrical contacts either between electrode constituent particles or with current collector leading to the failure of the battery. One of the modifying methods of silicon materials is to composite it with carbon materials, and the stress concentration will be absorbed by the carbon material.So the cycle performance of silicon materials is improved.In this paper, by using silane as silicon source, carbon nanotubes, commercial graphite, graphene as matrix, we have made three different structures of silicon/carbon composite material through chemical vapor deposition method. The composite material with carbon nanotubes as the matrix effectively alleviates the volume effect of the material, and when the charge/discharge current is 50mA, the first discharge capacity is up to 1357.5mAh/g.The reversible capacity of the composite material with commercial graphite as the matrix,under the same conditions, still can be stable at 500mAh/g after 50 cycles.Graphene matrix composite material under the same conditions,the first reversible capacity of which is up to 1087mAh/g with an excellent cycle stability. The three different structures of carbon matrix in the composite not only reduce the volume expansion of silicon, but also increase the conductivity of the material, which significantly improves the electrochemical properties of the materials.