Study On Preparation And Electrochemical Properties Of Carbon Composites For Lithium Ion Batteries

Because of its friendly to environmental,long cycle life,portable small characteristics,Lithium-Ion Battery(LIB)is widely used in digital equipment,new energy vehicles,electric tools and other fields.At present,with the increasing demand for LIBs,electrode materials have become a research hotspot in the development of the new generation of LIBs.Carbon materials are widely used in the field of lithium ion electrode materials due to their characteristics of good conductivity,diverse morphology and structure,simple preparation.With the development of material science technology,more and more carbon composite electrode materials begin to emerge.The combination of target material and carbon material can not only improve the conductivity of the composite material,but also effectively inhibit the volume change of the active material and maintain the structural stability.In this paper,LiFePO4 nanoparticles were prepared by a simple hydrothermal method instead of the traditional precursor sintering method,and LiFePO4 and nitrogen-doped carbon coated(LiFePO4/N-C)nanoparticles were successfully obtained using dopamine hydrochloride as carbon source.Modified nanoscale LiFePO4 material and carbon material composite,LiFePO4/N-C electrode has excellent cycling stability,158.4 mAh·g-1 reversible specific capacity after 200 cycles.It also has excellent capability in high rate current density.The specific capacity remains 107.5 mAh g-1 at 30 C.In order to explore the electrode material with better capacity and performance,the composite of two-dimensional structure metal sulfide FeS2 and carbon material in this paper.FeS2 nanoparticles were obtained by solvent thermal reaction,and was coated with glucose as carbon source.The synthesis method is simple and convenient.The morphology of carbon-coated FeS2(FeS2/C)is spherical with a diameter of 500?600 nm and a layer of amorphous carbon coated on its surface with a thickness of about 4?5 nm.FeS2/C composites exhibit excellent electrochemical properties.At the rate of 0.3C,the specific capacity stabilized at 683.8 mAh·g-1 after 100 cycles.Moreover,it performs well in of charge/discharge under high rate current test of 0.3C?1.8C.The electrochemical properties,cyclic stability and high-rate performance of FeS2/C material are significantly better than pure FeS2 materials.In this paper,SnS2/carbon paper(SnS2/CP)composites with nano-sheet structure were synthesized in one step by solvent thermal reaction.The method is simple.SnS2 nanosheets grow uniformly and densely on the surface of carbon paper.Carbon paper fiber provides a base as support,effectively inhibits the agglomeration of active materials,and improves the conductivity of composite materials.SnS2/CP composite showed excellent lithium storage performance.At the current density of 100 mA·g-1,the specific capacity was maintained at 800 mAh·g-1 after 60 cycles.The cycling stability and high rate performance of SnS2/CP composites are significantly better than those of pure SnS2.