Synthesis And Electrochemical Behaviors Of Titanium-based Oxide/Graphene Aerogel Complexs

As the most promising anode material for lithium-ion batteries,spinel lithium titanate Li₄Ti₅O₁₂?LTO?has attracted much attention from scholars at home and abroad for its high voltage platform?1.55 V,vs.Li/Li⁺?,"zero strain"characteristic,good stability and remarkable cycling performance.However,LTO material is also has some shortcomings,and its poor electronic conductivity enormously hinders its wide application at domain anode of lithium battery materials.Therefore,researchers have been trying to explore the modification of LTO to improve its electronic conductivity.Because of the unique properties of grapheme,such as stable structure,excellent conductivity and large specific surface area,it has become a hot topic in the research of cathode materials for lithium batteries to combine graphene with LTO.However,it is found that the application of graphene with two-dimensional structure in the anode materials of lithium batteries has great defects,which can easily lead to the agglomeration of the materials and affect its properties.Therefore,in this paper,the three-dimensional pore structure of graphene is realized by self-assembly of graphene in lamellar structure,and the aerogel of graphene in three-dimensional sponge was formed.The three-dimensional graphene aerogel was combined with LTO to improve the electrochemical performance of the materials.In this paper,the structure of two-dimensional graphene was self-assembled and a three-dimensional structure graphene aerogel was prepared.The aerogels were used as conductive additives to composite with LTO nanoparticles,and a small amount of glucose was added as reducing agent and binder of composites.LTO nanoparticles and graphene aerogel were prepared by one step hydrothermal method.The results showed that the LTO/graphene aerogel complex was successfully synthesized.During the experiment,the hydroxyl group contained in glucose reduced the oxygen-containi-ng functional groups in GO.It can be seen from the TEM diagram,the composites are nanostructured particles,and these LTO particles are dispersed onto the graphene sheets.In addition,compared with the traditional LTO/graphene composite,the results show that the synthesized LTO/graphene aerogel composite has better lithium intercalation and lithium storage ability.At 0.5 C,the specific discharge capacity reached 189mAh g^-1,and the 167mAh g^-1was maintained at 30C.TiO₂ is an ideal lithium storage material with high theoretical capacity(specific capacity is up to 335mAh g^-1)and good safety performance,but its electronic conductivity is low,and the diffusion property of lithium-ion is weak.In this dissertation,TiO₂ and graphene aerogel nanocomposites with high conductivity were successfully synthesized by hydrothermal method.The crystal structure of the material was analyzed by XRD.The crystalline of TiO₂ in the composites is anatase type.The introduction of graphene aerogel could increase the specific surface area of TiO₂ nanomaterials and improves the dispersion of TiO₂ material.With the scope1.0V-2.5V voltage,the discharge specific capacity has reached 367.6 mAh g^-11 at 1C,and at 30C,the specific capacity can be maintained at 100mAh g^-1,which shows better cycling performance and stability than pure TiO₂ nanoparticles.Its excellent electrochemical performance is due to the role of TiO₂ and graphene,and graphene aerogels have conductive and dispersed effect on the materials,and also provide part of lithium storage capacity.