Synthesis And Electrochemical Performance Studies Of SnO₂Nanospheres/Graphene Composites For Lithium Ion Battery

New anode materials for lithium ion batteries with long cyele life and higheapaeity are needed urgently to meet the demands of portable electronic device andeleetric vehieles. Dwing to the high the theoretieal gravimetric lithium storage capaeity,SnO₂lithium storage materias have been considered as one of the most promisingalternative anode materials instead of carbon in lithium ion batteries. However, the largevolume change of the SnO₂materials often causes a drastic pulverization problemduring the lithiation/delithiation Proeess,Which leads to the rapid deterioration and lowretention of the eapaeity. Recent researehes indieate that SnO₂nanostructures can solvethe above mentioned problem to a large extent. Therefore, the simple, large-quantitysynihesis of SnO₂nanomaterials is of great signifieance.In this paper, we have prepared the SnO₂microspheres, graphene, and SnO₂nanospheres/graphene composites, on the basised of those, the as-synthesized tin-basednanostruetures and their nanoeomposites have been applied as anode materials oflithium ion batterie, the main irmovative results are listed as follow:1) SnO₂microspheres were synthesised by the hydrothermal method, meanwhile,we report on the effect of different ethanol/water solvent ratios, with the thermal time,on the morphology of SnO₂via the hydrothermal method. among them, SnO₂microspheres were tested for lithium ion battery, the results showed that the firstdischarge-charging capacity is1546mAh/g and951mAh/g at the current density of100mA/g, respectively. Their initial coulombic efficiency was approximately61%. Whichretained a reversible capacity of439mAh/g after30cycles.2) graphite oxidation was prepared by modified Hummers’ method, with naturalflake graphite as raw material. Then the graphene was got by heat expansion fromgraphite oxide. Structure, morphology and electrochemical performance of graphenewere studied. Graphene electrodes of initial discharge capacity can reach1200mAh/g atthe current density of100mA/g, rataining discharging capacity of436mAh/g.3) Nanocomposites consisting of SnO₂and graphene have been achived. Structure,morphology and electrochemical performance of SnO₂nanospheres/graphenecomposites were studied. Results show that there were formed some bridge bondsbetween the SnO₂and the graphene duing to some functional groups on the surface ofthe graphene,which make SnO₂nanospheres disperse in the graphene uniformly. SnO₂ nanospheres/graphene composites electrode of initial discharge capacity can be up to1306mAh/g at the current density of100mA/g, the capacity of SnO₂nanospheres/graphene composites maintained592mAh/g after50cyeles.