Study On Polyaniline Coating Graphitized Diamond Micropowder And Its Supercapacitor Properties

Diamond possesses excellent physical and chemical properties,including ultrahigh hardness,good chemical and electrochemistry stability and resistance to acid and alkali corrosion.Diamond micropowder can be prepared with a great yield by airflow crushing method.Compared with nano-diamond,micro-diamond have the advantages of lower price,higher output,better dispersion and more concentrated size.Silicon oxide is incorporated during the particle size fractionation of the diamond micropowder.The diamond was treated with an HF solution to obtain a clean surface diamond micropowder.In order to improve the electrical conductivity of the diamond micropowder,the diamond is annealed by a spark plasma sintering apparatus to obtain a surface graphitized diamond micropowder.Using XRD,SEM and Raman,it found that the anealing time,anealing temperature,and the size of sample have influence on the graphitization degree of diamond micropowder.At the same annealing temperature and time,the larger the particle size,the lower the degree of diamond graphitization.For diamond of the same particle size,the higher the annealing temperature,the heavier the degree of graphitization.The high temperature annealed diamond possesses a core/shell structure.The core is diamond,and the outer layer is a growth controllable graphite layer.At1450 ~oC,diamonds with an average particle size of 1?m were annealed for 15 min to obtain samples with good electrical conductivity.Polyaniline(PANI)coated on the surface of the diamond before and after graphitization by chemical polymerization.Observation of the composite revealed that the lamellar polyaniline was tightly wrapped around the surface of the diamond,and the two were well composited.Cyclic voltammetry tests show that the graphitized diamond coated polyaniline composite as an electrode shows a synergistic effect of double layer and tantalum capacitance.After graphitization,the diamond is compounded with polyaniline,and the internal resistance of the composite is lowered,and a high specific capacitance can be maintained at the same current density.Due to the good dispersibility of 1?m diamond,the charge and discharge performance of the sample on the diamond surface before and after graphitization of polyaniline was stable.Among them,the average diameter of diamond is 1?m,and the sample with annealing temperature of1450 ~oC composite polyaniline(PANI@Gra1450/1Dia)specific capacity can reach471.52 F/g at 0.5 A/g The superior specific capacitance of PANI@Gra1450/1Dia is mainly attributed to the good surface conductivity of graphitized diamond and the close connection between PANI and Gra1450/1Dia matrix.The graphitized surface layer of diamond micropowder provides a reliable charge transport path for material charge and discharge.After charging and discharging more than 200 cycles,PANI@Gra1450/1Dia has a capacitance retention of 80%due to the large interaction area between the active material and the electrolyte.This shows that the graphitized diamond polyaniline composite material is a very potential supercapacitor electrode material.