Controllable Preparation,Microstructure Of Three Dimensional Carbon Superparticles And Their Electrochemical Energy Storage Performance

The development of commercial supercapacitors based on carbon materials is disturbed by low energy density.Some research show that the energy storage density can be improved by optimizing the microstructures and physicochemical properties of the carbon materials.However,the increase in energy density is usually accompanied by the damping of power density.In view of these problems,a novel kind of three-dimensional carbon supersparticles is developed.And we mainly focus on the mechanism of how microstructures of the three-dimensional carbon supersparticles influence the double layer capacitance.Its application in flexible solid state microsupercapacitors is discussed.The detailed research contents are as follows:?1?In the case of the carbon-based electrode materials,we prepare novel carbon supersparticles by in-situ conversion and ex-situ confined template assembly methods.In this facile Mgo template method,reactive metal Mg acts as a reducing agent and CO₂ is converted into three-dimensional carbonaceous material with hierarchally porous structure,rough surfaces with secondary structures,high accessible specific surface area(1001 m² g^-1)and good electrical conductivity(up to 2700 S m^-1).In ionic liquid electrolyte,the assembled supercapacitors based on carbon supersparticles deliver high energy density of 46.5 Wh kg^-1and high power density of 52.5 kW kg^-1.And the supercapacitors exhibit good rate performance and long-term cycling stability.The critical problems of carbon-based electrode materials referring to low energy density and rapid attenuation of energy density at high power density are sovled.?2?Using ultraviolet laser cutting and spraying technologym,the novel carbon supersparticles are coated on paper substrate as flexible electrode.Combined with PVA/H₂SO₄gel,which plays a dual role of electrolyte and separator,flexible solid state microsupercapacitor are fabricated.The effect of electrode edge structure on ion transport performance of supercapacitors is systematically studied..The result have shown that the decreasing interdigital width will help to the rapid transportation of electrolyte ions,thereby facilitating the efficiency establishment of double layer capacitance.With the electrode thickness of 4.5?m,the optimized flexible solid state microsupercapacitors exhibit an areal specific capacitance of 7.3 mF cm^-2 and a volumetric capacitance of 16.2 F cm^-3.And the specific capacitance is maintained at 104.4%of the initial value after 10,000 cycles.In addition,the flexible,lightweight,patchable and easily integrated properties of the flexible solid state microsupercapacitors will help to promote their practical application in flexible and wearable electronic devices.?3?The PVDF-HFP is cross-linked with TEABF4/PC or EMIMBF4 to construct flexible solid electrolytes.Taking its advantage of high operating voltage and suited electrolyte ion sizes,the energy storage density of the flexible solid state microsupercapacitors are enhanced.The ionic conductivity of the as-prepared solid electrolyte varies with temperature in Vogel-Tammann-Fulcher relationship.With the supporting of PVDF-HFP@TEABF₄/PC and PVDF-HFP@EMIMBF4 gel polymer electrolytes,the as-prepared MSCs have higher working voltage up to 2.5 and 3.0 V.And the energy densities increase to 2.6 and 4.7?Wh cm^-2,respectively.