Research On Construction And Supercapacitive Properties Of Three-dimensional Porous Carbon Material And Its Composites

Supercapacitor have attracted researchers more attention because of high energy density,fast charging and discharging,low cost,environment-friendly and so on.Electrode material and electrolyte are significant factors to affect the performance of supercapacitor,which as important components of supercapacitor.At present,porous carbon material as one of the most widely used double-layer electrode materials,it is very important to rational design and optimize the structure for achieve excellent performance.What’s more,molybdenum carbide is a potential energy storage material due to its advantages of high conductivity,low cost,high chemical stability and so on,whereas little research has been done on supercapacitor because of the limitation of preparation condition.Recently,some studies to improve the synthesis process by combining with carbon materials with superior structure,and has some achievements.The purpose of this article is to prepare high-performance electrode material for supercapacitor,a simple,efficient and easy accessibility method were used to construct the electrode materials with three-dimensional porous structure characteristic,the structure and morphology were analyzed by XRD,SEM,TEM and other characterization methods,its electrochemical properties were examined in aqueous and ionic liquid electrolyte system,and the influence of material structure on electrochemical energy storage was investigated by systematic electrochemical analysis.The specific research work as follows:（1）Corn starch with rich source and simple composition was selected as the raw material,a starch gel precursor with three-dimensional reticular structure was constructed by sol-gel method,then 3D-reticular porous carbon material（3D-RPC）was prepared by one-step carbonization,which presents a high specific surface area and multi-channels interlacing structure of macropores,mesopores and micropores.This structure characteristic provides more active sites and is beneficial to the penetration and transport of electrolyte ions,leading to achieve excellent electrochemical performance.The 3D-RPC shows a high specific capacitance of 372 F g^-1(0.5 A g^-1)in aqueous electrolyte.To further obtain a high energy density,using ionic liquid as electrolyte,achieving a wide potential window of 2.6 V,a specific capacitance of 218 F g^-1(0.5 A g^-1),and the 3D-RPC//3D-RPC shows an ultrahigh energy density of 24.5 Wh Kg^-1 at the power density of 695 W Kg^-1.（2）A three-dimensional hierarchical porous carbon loaded Mo₂C（3DHPC-Mo₂C）nanomaterial with large specific surface area and superior structure was prepared through combination of NaCl template and K₂CO₃ in-situ activation method.The introduction of 3D hierarchical porous carbon matrix accelerates the rapid penetration and transport of electrolyte ions as well as effectively prevent the excessive growth and agglomeration of molybdenum carbide during the high-temperature preparation process,to synthesis small-sized Mo₂C nanoparticles that beneficial to develop its excellent characters,such as high conductivity.Electrochemical analysis shows that:3DHPC-Mo₂C demonstrates a high specific capacitance of 206 F g^-1(0.5 A g^-1)and excellent cycle life（keep 96.6%of initial capacitance after 7000 cycles）in aqueous electrolyte.Furthermore,the asymmetric supercapacitor was assembled with activated carbon in ionic liquid electrolyte,showing a high energy density of 20 Wh Kg^-1 at the power density of 224 W Kg^-1.（3）A Cu/Mo based MOFs precursor was synthesized by use the MOFs-assisted strategy,then three-dimensional hierarchical porous carbon loaded Mo₂C nanomaterial（Mo₂C/C）with large specific surface area and abundant pores has been developed via carbonization and etching of Cu,among which the abundant pores were mainly derived from the remove of metal Cu particles.The Mo₂C/C shows the structural characteristics that dominated by mesoporous and Mo₂C is evenly dispersed on the octahedral carbon matrix with ultra-fine nanometer size.The in-situ carburization method with MOF as the precursor can effectively inhibit the overgrowth and accumulation of molybdenum carbide,generating ultrafine nano-sized Mo₂C crystalline,and the structure exhibits excellent stability.Electrochemical analysis shows that:In the ionic liquid electrolyte,the Mo₂C/C display a superior cyclic stability that the capacity almost no attenuation after 8000 cycles.The asymmetrical supercapacitor assembled with activated carbon exhibits an energy density of 12 Wh kg^-1 at the power density of 87 W kg^-1.