Synthesis And Electrochemical Performance Of SnO₂ Anode Materials For Lithium Ion Battery

SnO₂ has many advantages such as high theoretical capacity（782 mAh/g）,simple preparation method,non-toxic side effects,etc.So it is regarded as a kind of promising anode material for lithium ion battery.However,the volume expansion will led to SnO₂ material pulverization,reunion,poor capacity of recession in the practical application of lithium ion battery cathode material.So,it is hence of great the oretical and practical significance to research the surfactant regulate and control Sn O₂ morphology,SnO₂ with carbon composite and doping with Mn²⁺,Zn²⁺,In³⁺ metal ions for the preparation of SnO₂ cathode material with superior performance.SnO₂ anode material was prepared by hydrothermal method with sodium stannate as raw material and polyvinylpyrrolidone（PVP）,sodium dodecyl sulfate（SDS）and urea as surfactant,respectively.The morphology,structure and electrochemical performance of the material was characterized by using scanning electron microscope（SEM）,X-ray diffraction（XRD）and electrochemical technique.The results showed that the surfactants had a great influence on the morphology,and the different morphology of SnO₂ material had large influence on the electrochemical properties.The morphology of Sn O₂ anode material was modified by PVP that its morphology for loose balls nanorods,by SDS modified was rough sphere,while by urea modified for good dispersancy smooth sphere.The initial discharge capacity of three different morphology of SnO₂ material reached 1551.3mAh/g、1751.2mAh/g、2256.6mAh/g respectively at the rate of 200mA/g and at 0.01 3.0V,the discharge capacity were retain 1619.2mAh/g、1444.6 mAh/g 、1319.9mAh/g after 50 cycles.It is showed better cycle stability that compared with the unmodified SnO₂ material.SnO₂/C composites were prepared by hydrothermal method with sodium stannate as raw material,glucose,sucrose and pyrrole as carbon source,respectively.The structure and electrochemical performance of the material was characterized by using X-ray diffraction（XRD）and electrochemical technique.The results showed that the precursor of composite material’ SnO₂ did not decompose in argon atmosphere after 500℃ carbonation.The initial discharge capacity of SnO₂/C composites with glucose,sucrose and pyrrole as carbon source reached 1029.2 mAh/g,1385.8mAh/g,1282.5mAh/g respectively,the initial coulomb efficiency were 57.4%、46.9%、66% respectively,higher than that of SnO₂ particles（46.1%）.The discharge capacity was keep 381mAh/g、406.8mAh/g、478.7mAh/g after 50 cycles,but the SnO₂ particles was only 150mAh/g.It is showed better cycle stability that compared with the pure SnO₂ material.So,SnO₂/C composites have high coulomb efficiency and good cycle stability.The different metal ions doped SnO₂ material was prepared by hydrothermal method with sodium stannate as raw material,urea as the precipitator,and Zn2 +,Mn2 + and In³⁺ as doping metal ions,respectively.The structure and electrochemical property of the material was characterized by using X-ray diffraction（XRD）and electrochemical technique.The results showed that doping a little of metal ion only as impurities exists in the crystal lattice of SnO₂ material,and did not change the crystal structure of the material.The initial discharge capacity of SnO₂ material with doping content 10%Zn²⁺、10%Mn²⁺ and 5%In³⁺ were 1619.2mAh/g、1444.6mAh/g 、1319.9mAh/g,respectively,the initial coulomb efficiency 44.4%、83.3% and 51.4% respectively,at the current density of 100 mA/g,over the voltage range of 0.01³.0V.And the discharge capacity retention was 12.8%、11.9%、36.6% respectively after 50 cycles.The initial coulomb efficiency and the capacity retention after 50 cycles were better than undoping SnO₂ material（initial coulomb efficiency was 41.1%,capacity retention was only 8% after 50 cycles）...