The Synthesis Of Semiconductor Oxygen-Containing Compound/graphene Composites For The Anode Of Sodium-ion Batteries

Lithium ion batteries(LIBs)have been used as portable power supply in various fields,due to their high working voltage,light weight,high energy density,and so on.However,when the large-scale applications of LIBs become widespread,the potential problems in the past about the cost of lithium,limitation of lithium terrestrial reserves and the safety of LIBs have been increasingly concerned.Since sodium metal possesses more advantages than lithium metal,such as abundant resource,low cost and uniform distribution,and sodium ion exhibits similar chemical properties to Li ion,sodium-ion batteries(SIBs)have attracted considerable attention as an appealing alternative to LIBs.Although the energy density of SIBs is lower than that of LIBs,SIBs is still a good choice in many applications,such as the energy storage in the power station,where the energy density is not a major issue.SIBs is a complicated system,in which the anode material plays an important role in affecting the sodium-ion storage capability and cycling ability.However,the study of anode material of SIBs is still in a fundamental research stage.In this thesis,the different metal oxide and reduced graphene oxide(RGO)composites were successfully fabricated and used as anode materials of SIBs to investigate their electrochemical properties.The main contents of this thesis are summarized as followed:1.Sb2O3/RGO composites were prepared through a facile microwave-assistedmethode and used as anode materials for SIBs.The experimental results show the size of Sb2O3 nanoparticle decreases after the introduction of RGO and the specific surface of Sb2O3/RGO composites increases with the increase of RGO content.The Sb2O3/RGO composites exhibit better cycling stability than Sb2O3.And a maximum specific capacity of 503 mAh g-1 is achieved after 50 galvanostatic charge/discharge cycles at a current density of 100 mA g-1 by optimizing the RGO content in the composites and an excellent rate performance is also obtained.2.The porous CuO/RGO composites were obtained through the pyrolysis of Cu-based metal-organic frameworks/graphene oxide under microwave irradiation,and investigated as anode materials for SIBs.The results show that the CuO nanoparticles are tightly attached on RGO sheets and the specific surface area of CuO/RGO composites increases with the increse of RGO content.And the optimized CuO/RGO composite exhibits a maximum specific capacity of 475.6 mAh g-1 after 160 galvanostatic charge/discharge cycles at a current density of 100 mA g-1 Even at high current density of 2 A g'1 after 580 cycles,it can deliver a reversible capacity of 308.2 mAh g-1.3.NiCo2O4 nanorods/RGO(NCO/RGO)composites were synthesized through a simple solvothermal method followed by a thermal annealing process,and they were used as anode material of SIBs.The results show that when RGO is introduced into NCO,the size of NCO nanorods decreases.And the NCO/RGO composites exhibit a high maximum capacity of 422.1 mAh g-1 after 50 cycles at a current density of 100 mAg-1.Furthermore,even at a high current density of 2000mA g-1,a capacity of 275.1 mAh g-1 is still maintained,which surpasses those of most previously reported NCO.4.CuCo2O4 nanoparticles/RGO(CCO/RGO)composites were synthesized through the solvothermal method followed by a thermal annealing process,and they were used as anode materials of SIBs for the first time.The results show that the CCO nanoparticles with relatively uniform size are well attached on RGO and the composites display an improved performance compared with the CCO nanoparticles.The optimized CCO/RGO composite maintains a capacity of 421.2 mAh g-1 at a current density of 100 mA g-1 after 50 cycles,and also exhibits a good rate capability.