Preparation Of Carbon Materials Derived From Corn Stalk Core And Research On Performance Of Supercapacitors

With the sustainable development of economy,problems such as energy shortage and environmental pollution are serious increasingly.Primary way is to search for a kind of green power.As a kind of electrical energy storage device,supercapacitors combine the merits of both conventional capacitors and batteries.Supercapacitors have been widely applied in the field of mobile devices,electric vehicles and aerospace due to their large power density,rapid charge and discharge and good cycling stability.Electrode materials are the crucial factor to influence the performance of supercapacitors.Owing to the traits of low cost,high conductivity,controllable porous structure and high surface area,carbon materials are widely applied to supercapacitors as electrode materials.However,carbon materials always derived from non-renewable resources,such as oil and coal.As a result,the researched point is to look for renewable and pollution-free raw materials.Using agricultural waste as raw materials,can make maximum use of resources,reduce environment pollution and lower cost.Therefore,in this paper,the carbon materials were prepared using corn stalk as raw materials.The main content of this paper includes:?1?Considering activated temperature was the crucial factor to influence the electrochemical performance of carbon materials,the other experiment conditions such as hydrothermal temperature,hydrothermal time,activated time and the concentration of alkali were selected preliminarily.The optimal prepared conditions were selected as 150°C,3 h,1h and 3 mol·L^-1 for hydrothermal temperature,hydrothermal time,activated time and the concentration of alkali,respectively.On the basis of conclusion,the influence of activated temperature to carbon materials was studied.The optimal activated temperature was 700°C.In the current density of 1 A·g^-1,CSC-700 performed an excellent capacity of 160.1 F·g^-1.After 1000 cycles,about 87.9%of the capacity was maintained.After 5000 cycles,only 4%of the capacity was lost in the high current density.It indicated the excellent performance of rate and stability.CSC-700 possessed high specific surface area(1440.45 m²·g^-1)and porous structure,which attributed to the transition and insertion-extraction of electrolyte ion and enhance the electrochemical performance observably.?2?According to the literature,doping is an effective way to enhance the capacity.In addition,Ni?NO₃?₂ could increase the specific surface area.Therefore,the spongy structure in the corn stalk core was used to absorb Ni?NO₃?₂ solution,and then the corn stalk core was carbonized and activated to prepare Ni-doped activated carbon materials.The 2%was selected as the optimal one,compared to different doped density.CSC-2%performed a capacity of 109.4 F·g^-1 in the current density of 1 A·g^-1 and the capacity attenuation rate only was 3.5%when the current density increased five times.In the current density of 1 A·g^-1 and5 A·g^-1,the capacity could maintain 81.9%and 85.7%after 1000 cycles and 5000 cycles.However,compared with CSC-700,the capacity of doped sample was inferior to un-doped.?3?Considering the prepared cost and complicated procedure,on the basis of chapter three,the prepared method was improved.The lignin was removed through reaction with alkaline liquor,leaving the cellulose to be carbonized.It could not only lower cost,but simplify the prepared process.The optimal carbonized temperature was 600°C compared with other different carbonized temperature.CE-600 delivered an outstanding capacity of154.2 F·g^-1 and the capacity remained 88.7%when the current density increased five times.In the current density of 1 A·g^-1 and 5 A·g^-1,the capacity could maintain 76.4%and 92%after 1000 cycles and 5000 cycles,which indicated the excellent performance of stability at high currrent density.Compared with CSC-700,the capacity level of CE-600 was similar to it.