Investigation On Synthesis And Application Of Graphene Nanocomposite Foams

Derived from graphene,foam graphene not only provides inherently excellent properties of graphene materials,but also exhibits huge specific surface areas,strong mechanical strength and fast mass transport kinetics.Foam graphene materials have triggered tremendous interests owing to these unique properties.In this study,using graphene oxide?GO?as the precursor,three dimensional GO/PVA foam and its reduced GO/PVA foam?r-GO/PVA?nanocomposites were successfully synthesized using a freeze-drying method followed by thermal treatment.Detailed studies on chemical composition,microstructure and mechanical properties of the 3D foams have been carried out.In order to investigate its application in lithium ion batteries,SnO₂ as an anode material was prepared by hydrothermal method.The effects of hydrothermal temperature in terms of morphology and electrochemical properties have been studied.Moreover,r-GO/SnO₂/PVA 3D materials were fabricated using the same methods and its electrochemical properties have been discussed as well.The main results and new findings of this work are summarized as follows:?1?GO/PVA nanocomposites were synthesized by freeze-drying method,which possessed homogeneous pore structures.With control of PVA content,the pore size can be well tuned.Besides,increasing the PVA content,the compressive strength and modulus showed increasing trends.After thermal reduction under argon atmosphere at 300 ?,the r-GO/PVA foam showed better conductivity.The compressive strength and modulus of r-GO/PVA were lower than those of GO/PVA materials.?2?SnO₂ nanomaterial was fabricated by hydrothermal method and systematically characterized.The results showed that with the increase of temperature,the morphology of SnO₂ changed from nanoparticals to nanorods.Using the SnO₂ nanorods which were prepared under 240 ? as anode material for lithium ion batteries,it possessed high initial discharge capacity?1401 mAh/g?and revealed a capacity of 350 mAh/g?at 500 mA/g?up to 100 cycles.?3?Evenly dispersing the SnO₂ nanorods into GO solution,followed by freeze-casting method,r-GO/SnO₂/PVA nanocomposites were successfully prepared.It exhibits excellent electrochemical properties as an anode material for Li-ion battery.The initial Coulomb efficiency was greater than 60%and owned a capacity of 709.9 mAh/g?at 500 mA/g?up to 100 cycles.Moreover,the material showed a high rate performance.It remained a capacity around 500 mAh/g at 4 A/g current density.