Study On The Structure Of Starch-based Carbon Microsphere Material And Its Application In Electrochemical Capacitor

As a new precursor of carbon material, the advantages of potato starch includedenvironment-friendly, renewable, extensive, low-cost, containing abundant carbonelement and small amounts of miscellaneous elements, and owning a natural globularstructure. If the natural globular structure could remain successfully during thecarbonization of starch through some method, carbon microspheres with goodsphericity would be obtained. In this paper, different inorganic compounds were usedas promoter agents to prepare potato based carbon microspheres, and the differentpreparation mechanisms and characteristics of potato based carbon microspheres werestudied. In addition, activated carbon microspheres were obtained by some activationmethods, and the electrochemical performance of these activated carbon microsphereswas measured.In this paper, different inorganic compounds （phosphoric acid, ammoniummonohydric phosphate, ammonium chloride） were used as promoter agents to preparepotato starch based carbon microspheres with different carbon microstructure.Phosphoric promoter agents （phosphoric acid, ammonium monohydric phosphate）and ammonium chloride played different roles on carbonization process. Moreover,ammonium salt promoter agents （ammonium monohydric phosphate, ammoniumchloride） were in favor of forming graphite-like micro-crystal, and phosphoricpromoter agents （phosphoric acid, ammonium monohydric phosphate） were in favorof forming turbostratic graphite structure during the carbonization process.Potato starch based carbon microspheres obtained by acceleration effect ofphosphoric acid, were activated by KOH at different conditions to prepare activatedcarbon microspheres, which were used as electrode material of EDLC. The resultsshowed, potato starch based activated carbon microspheres in6mol L^-1KOHexhibited good electrochemical performace, especially at large current density. Theproduct obtained at KOH/C=4:1showed excellent rate property. Even when the scanrate reached400mV/s, the cyclic voltammetry curve still remained rectangular shape.At the current density of48.9A/g, the mass-specific capacitance was217F/g. Using potato starch as raw material, through H3PO4—steam couplingactivation method, the starch-based activated carbon microspheres with reasonableporous texture were obtained. The study results showed, with the increase ofactivation time, the porous texture and mesopore content obviously increased. Duringthe electrochemical test in6mol L^-1KOH, the obtained starch-based activated carbonmicrospheres showed good electrochemical performance.