Preparation And Electrochemical Properties Of Polyaniline/Carbon Composites

Supercapacitors?SCs?are a kind of green and pollution-free energy storage device due to their unique energy storage properties.The performance of SCs is highly determined by electrode materials.Therefore,the design and synthesis of novel nanostructured electrode materials with high specific capacitance and long cycle life as well as low cost is the critical in promoting the wide application of SCs.Polyaniline?PANI?as typical Faraday pseudocapacitance electrode material has the advantages of high theoretical pseudocapacitance,facile synthesis and low cost.However,low rate performance and poor cycling stability seriously restrict its application.Carbon materials as a double-layer capacitance electrode material have excellent electrical conductivity,superior mechanical and chemical stability.Therefore,the combination of PANI with carbon materials to prepare polyaniline/carbon composites,which makes full use of the synergistic contribution of each component,can effectively improve the electrochemical properties of the material.Supercapacitor electrode materials with excellent overall performance such as high specific capacitance,high energy density and good cycle life can be obtained.In this paper,different morphologies of PANI are synthesized,and we combine poly?acrylic acid??PAA?hydrogel modified carbon nanotubes?P-MWCNT?,nitrogen doped carbon spheres?NCS?and nitrogen doped carbon sheets?HPCNS?with PANI to prepare different polyaniline/carbon composites.Their structures and morphologies are characterized,and electrochemical performance tests are also carried out.The electrochemical performance of polyaniline/carbon composites has been significantly improved compared with pure PANI.The main contents are follows:?1?Tubular PANI are successfully prepared by chemical oxidation polymerization with aniline as the monomer,camphorsulfonic acid as the doping acid and cetrimonium bromide as the surfactant.In order to improve the performance of PANI,PANI/MWCNT and PANI/P-MWCNT composites are prepared by in-situ polymerization method,and their structure and electrochemical properties are characterized.Electrochemical test results show that PANI/P-MWCNT hybrids has excellent electrochemical performance.Its specific capacitance of 612.5 F g^-1 at 0.5 A g^-1,rate performance of 75.2%capacitance retention at 3 A g^-1,and cycling behavior of 81.5%retention at 5 A g^-1 over 1500 cycles,are delivered.Also,the maximum energy and power densities of the PANI/P-MWCNT based symmetric configuration are 8.2 Wh kg^-1 and 1319.6 W kg^-1,respectively.?2?Flower-like PANI are obtained by chemical oxidation polymerization with aniline as the monomer and sulfuric acid as the doping acid.In order to improve the performance of PANI,double-shelled composites?PANI/NCS?of flower-like PANI located on NCS are prepared by in-situ chemical polymerization.Structure and electrochemical performance of composites are characterized.The results of electrochemical tests indicate that the composite with 32 wt%NCS possess higher specific capacitance(660.0 F g^-1)at a current density of 0.5 A g^-1.Moreover,the composite displays rate performance of 73%retention at a current density of 5 A g^-1.Additionally,the fabricated symmetric configuration exhibits a maximum energy density of 8.0 Wh kg^-1 and a maximum power density of 1750.0 W kg^-1.?3?Fibrous PANI are successfully prepared by chemical oxidation polymerization with aniline as the monomer and camphorsulfonic acid as the doping acid.In order to improve the performance of PANI,fibrous PANI is grown on the surface of HPCNS by in-situ polymerization to prepare PANI/HPCNS composites with different HPCNS content.Structure and electrochemical performance of the composites are characterized.The electrochemical performance test results show that the composite with 32 wt%HPCNS has the highest specific capacitance up to 680.1 F g^-1(0.5 A g^-1),showing the best rate performance of 75%.The capacitance value of single electrode in two-electrode setup is 415.9 F g^-1 at 0.5 A g^-1,and a retention of79.4%is achieved at 10 A g^-1.The maximum energy density and power density are 9Wh kg^-1(0.5 A g^-1)and 950.6 W kg^-1(10 A g^-1),respectively.After 2000 cycles,the capacitance retention rate is 70.5%.