Synthesis And Carbonization Of Polyaniline Nanomaterials And The Capacitive Performance Of Carbonized Products

Supercapacitor is a rapid charge/discharge energy storage device, which combines the advantages of both rechargeable batteries and traditional capacitor with higher power density and longer service life. In supercapacitor study, The electrode materials control the performance of supercapacitor. This work focuses on the preparation of high-capacitance electrode materials and will have important application value and theoretical significance.In this paper we used ammonium persulfate (APS) as oxidant, hydrochloric acid as doping agent, through the microemulsion method, interface method and Chemical oxidation method to make different nano-structured polyaniline materials. By optimization we picked out polyaniline nanofiber as the carbon precursor, then by further preoxidation and high temperature carbonization, polyaniline nanofibers will be transformed into nitrogen-doped carbon nanofibers. The influences of reaction conditions on the polyaniline morphology and the electrochemical properties of different carbonization products were investigated.Through controlling the concentration ratio of hydrochloric acid, ammonium persulfate and aniline, we can get polyaniline materials with various morphologies such as balls, hollow tubes and fibers. In microemulsion system the spherical polyaniline possesses the diameter of about 0.5～2μm, and the Polyaniline fiber shows the diameter of about 100nm. By adjusting the oxidant dosage, we can get polyaniline fibers from nanoscale to microscale. The flake-type polyaniline was also synthesized with the thickness of about 2nm and size of 1～2μm. In static interface method, the diameter of polyaniline fiber is about 20-100 nm. In dynamic interface method, the thickness of flake polyaniline is between several nano to several microns, and the size is about 3μm. By in-situ oxidation method polyaniline fiber shows the diameter of about 50 nm and length of about 100nm. At neutral condiation, we can get nanotubes with the diameter of 100 nm.After oxidation and carbonization, the morphology of polyaniline carbon nanofibers is maintained very well. As supercapacitor electrode material, Polyaniline-based carbon fiber has high capatance and good cycle properties. Especially the carbonation product at 700℃possesses the capacitance of 158 F·g-1 at the current density of 0.1 A·g-1. At 1 A·g-1 current density, the capantance is also remained 110 F·g-1 without any fading. suggesting that this material can be used as a new kind of ideal supercapacitor electrode materials...