Preparation Of Graphene Aerogel And Its Application As Electrode Materal In Super Capacitor

Graphene can be reassembled into 3D graphene,and produce abundant pore structures in this process,and also retain an excellent properties of graphene itself,it’s more conducive to the practical application.Graphene aerogels are usually made of graphene hydrogels,however,the applications of traditional methods to dry the hydrogel made though one-step hydrothermal method have been limited by their time-cost and money-cost.In respect of the issues above,this paper mainly carried out the study of preparation of graphene aerogel and its application as the electrode material in supercapacitor,and the contents of this paper are following aspects:(1)Found an easy method to dry graphene hydrogel,compared with the traditional drying methods,it can save a large of time and cost,and the materials still have larger specific surface area.We also doped different surfactants,found an optimization of the drying process.Graphene aerogel showed a large the specific surface area(731.77 m2/g)after the dispose of sodium lignosulfonate,other characterizations also showed a better microstructure and physical properties.the electrochemical performance tests also showed a high specific capacity(380.67 F/g at 1 A/g)in KCl aqueous solution;and the specific capacity could reach 648.5 F/g at 1 A/g with ionic liquids as electrolyte(energy density 5.188 k Wh/g)at the highest voltage 4 V.(2)The experiment via thermal expansion to compare the influence of tempreture(700 、 900、 1100 ℃)in combustion.Results of characterizations showed that the performances of the materials are not completely rasied with the rise of temperature.Sample presented a better microstructure and electrochemical properties(both in KCl and ionic liquid system)at 900℃: the specific capacity can reach to 251.4 F/g at 1 A/g,and retained 76% after 4000 cycles in KCl aqueous solution,and 495.7 F/g at 1 A/g in ionic liquid system test.(3)Experiment via the using of urea to achieve N-doped materials,aiming to explore weather the combustion drying method is suitable for the heteroatom doping experiment,and broaden the application scope of this method.We set up with the mess ratio of 15、30、60(urea: graphene oxide and mark as urea-15、30、60).BET tests showed that the largest surface area can reach 711.34 m2/g(urea-15),and the content of N atom increased with the increase of the urea quantity.But electrochemical test results showed that the performance of urea-30 is optimal in the ionic liquid system: the specific capacity can reach 995 F/g at 1 A/g(energy density 7.96 k Wh/g).The specific capacity retained 148.5 F/g at a large current density-100 A/g(15% capacity retained).