Dissertation > Mathematical sciences and chemical > Chemistry > Inorganic Chemistry > Metal elements and their compounds > Section Ⅳ group metal elements and their compounds > Main family of germanium ( IV A group metal elements ) > Tin Sn

Preparation and Lithium-ion Batteries Anode Properties of Spherical Stannic Oxide-Low-Dimensional Carbon Composite

Author FuMeiMei
Tutor HouChaoHui
School Xiangtan University
Course Physical and chemical
Keywords SnO2hollow nanosphere APS graphene carbon nanotube
CLC O614.432
Type Master's thesis
Year 2013
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Due to the high theoretical capacity of SnO2as negative electrode materials ofLi-ion battery, SnO2has attracted much attention. However, if SnO2was used to benegative electrode materials of commercial Li-ion battery, it had a few barriers. Onthe one hand, the poor electronic conductivity of SnO2enhances the internal resistanceof battery. On the other hand, during charge-discharge process, insertion andextraction of Li-ion are likely to cause strong volume change and high internal stressof negative electrode material, which lead to breakdown and disconnection ofnegative electrode materials. To prepare special structures of SnO2and composites ofSnO2and carbon materials, using various excellent characters of them solve theproblems to solve/remit the problems from being negative electrode material.Graphene and carbon nanotube have application prospect at different fields of storageequipment. They are good matrix of SnO2because of high conductivity and specialstructures.In this paper, the surface of SnO2hollow sphere prepared through hydrothermalmethod was modified by APS. Then the APS-modified SnO2hollow sphere wasencapsulated by graphene sheet or carbon nanotube, which gained the composite ofSnO2hollow sphere and graphene sheet/carbon nanotube. Comparing with commonSnO2, SnO2hollow sphere have preferably good cycle performance. After SnO2hollow sphere was encapsulated by graphene sheet/carbon nanotube, its cycleperformance and electrochemical performance were obviously enhanced. Concretecontent as follows:(1)In the alkaline environment of urea, SnO2hollow sphere was synthesized byhydrothermal method, potassium stannate as precursor and ethanol solution as solvent.The first invertible capacity of SnO2hollow sphere was1028mAh/g, higher thancommon SnO2(800mAh/g), at electric current density of156mA/g. It showedexcellent cycle performances over more electric current density.(2) At first, we selected SnO2hollow sphere that had appropriate size and highelectronic performance. The SnO2hollow sphere was modified by APS. ThenAPS-modified SnO2hollow sphere and graphene self-assembled through theelectrostatic interaction of them, which obtained graphene-encapsulated SnO2hollowsphere. When mass ratio of the composite was83%, the first invertible capacity was only924mAh/g at electric current density of156mA/g, but the30th invertiblecapacity was788mAh/g. It showed excellent cycle performances over more electriccurrent density.(3)The size choice and surface modification of SnO2hollow sphere were the sameas (2). In the air atmosphere and acid solvent, APS-modified SnO2hollow sphere andcarbon nanotube activated by strong acid were simply stirred to gain carbonnanotube-encapsulated SnO2hollow sphere. When mass ratio of the composite was71%, the first invertible capacity was995mAh/g at electric current density of156mA/g and the30th invertible capacity was653mAh/g. It showed excellent cycleperformances over more electric current density.

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