Preparation And Properties Of Graphene Based Binderless Electrode For Lithium Ion Battery

Graphene constructed by two-dimensional periodic honeycomb lattice structure which is composed of six-membered rings,is carbon materials.Three-dimensional structure of graphene not only has ultra-high porosity,but also has the smallest density of all the solids known in the world currently.In the present materials,the lightest three-dimensional structure is approaching 0.16mg cm^-3.Moreover,graphene aerogels has a astonishing specific surface area which is as high as 2630m²g^-1,the carrier migration rate reaches 5000W m^-1K^-1.After several tests,it reveals that graphene has a mechanical strength of 130GPa,which is 100times higher than steel.At the same time,through the utilization of three-dimensional and porous graphene aerogels,the excellent performance of graphene can be extended from the micro-domain to the macro-field.From two decades ago,Lithium`ion battery has been commercialize production as well as widely used in life and industry.It has been extensive applied in electric vehicles,portable electronic products and other new energy fields.In the traditional lithium-ion battery preparation process,graphite is mainly used as the anode material.However,with the development of modern society,limited by the theory capacity and energy density of graphite,the utilization of graphite for electrode cannot meet people's requirements.With the discovery of graphene at 2004,due to graphene has a single layer of two-dimensional structure and is easier to achieve the transfer of lithium ions in theory which will enhance the performance of lithium ions,graphene as a lithium-ion battery electrode obtain more and more attention and application in scientific research and industrial production.This paper mainly focuses on the preparation process of three-dimensional graphene aerogel and its composite material to explore.Moreover,such graphene aerogels will be used for the preparation of high-performance lithium-ion battery cathode material without any additives with an environmentally friendly,more economical and simple process.The main contents and conclusions of this paper are as follows:First,three-dimensional graphene hydrogel was prepared by freeze-drying.The high-temperature treatment of the graphene hydrogel was carried out in an inert gas atmosphere in order to improve the reduction degree of graphene oxide and remove the impurity.After high-temperature treatment,graphene oxide was further reduced to the ultra-light porous structure.Tin dioxide nano-particles were prepared by hydrothermal method,and combined with the graphene oxide layer by electrostatic attraction through stirring and ultrasonic treatment.After freeze-dried and high temperature reduction treatment,tin oxide nanoparticles and the graphene sheets were chemically bonded to each other and adsorbed more closely,resulting in a synergistic effect.Second,through the exploration of traditional preparation process of lithium-ion battery assembly process,several shortcomings were found.By adopting the prepared three-dimensional and porous graphene aerogels,the process flow was simplified significantly,making the new process more environmentally friendly,economical,succinct,greatly shorten assembly process from the preparation of negative material to lithium-ion battery.At the same time,by reducing the reduction temperature used in the preparation process,the new process was more adaptable to industrial production.Third,the electrochemical performance of the assembled Li-ion battery was tested by electrochemical workstation.Meanwhile,the control variable method was used to explore the effect of each variable parameter on battery performance.It was found that when the mass ratio of graphene to water was too small than1:500,the oxidized graphene hydrogel could not be obtained by reducing agent and heating.Secondly,when the concentration of oxidized graphene was 2mg ml^-1,the ratio of the graphene oxide to the tin dioxide nanoparticles was 1:1,the ratio of the graphene oxide to the reducing agent?ascorbic acid?was 1:10,and the graphene aerogels obtained after the freeze-drying and high-temperature treatment of 550°,the performance of Li-ion battery is the best,reaching850mAh g^-1?...