| This work focuses on the development of Si-C nanocomposite for anodes of lithium batteries.Different binders and carbon sources were used to test their effect to the electrochemical performance of the silicon anode electrodes.Then,Si-C nanocomposites with yolk-shell structure were synthesized using a facile route by replacing the SiO2 layer by MgO.In this work,nano-silicon particles were used as raw material.The precursor of the sacrifice layer was coated onto Si particles by precipitation in aqueous solution.Followed by calcination and CVD process,the precursor shell was turned into oxides and covered by carbon layer.As the metallic oxides in this experiment were soluble in acid,the HF etching process can be substituted by using diluted HCl,which is less toxic and corrosive.In this experiment,two metallic oxides Al2O3 and MgO were used as the sacrifice layer.With various of physical characterization and electrochemical tests,it was found that using MgO as the sacrifice oxide can obtain a better yolk-shell structure.On this basis,the amount of MgO coating also had been investigated.The proper mass ratio of MgO and Si can be approx.2 and a reversible charge capacity of991 mAh g-1 and 88.3%retention was achieved after 100 cycles at 1.0 A g-1,and 73.7%for 200 cycles.The significant improvements for cycle performance demonstrate the yolk-shell structured Si-C nanocomposite in this work is a promising anode material for lithium-ion batteries.This synthesis method is easy to achieve.The reagents used are more environmentally-friendly.It is possible for this method to be used to synthesize other yolk-shell structured composites,indicating the method have a great research value. |
