Capacitive Properties And Characterization Of Polyaniline Electrode Doped With Quaternary Ammonium Tetrachlorometallate

The supercapacitor is a new type electrochemical energy storage device between thetraditional dielectric capacitor and the battery. The supercapacitor can provide high energydensity, high power density, long cycle life and less pollution. As the electrode material ofsupercapacitors, conducting polymer has many advantages, such as, quick and efficientdischarge, withouting charge/discharge control circuit, long cycle life, temperature relief, andenvironmental amicability. It also possesses characteristics of semiconductor or conductorafter effectively doped. Polyaniline （PANI） is one of the most interesting conducting polymersdue to its environmental stability, ease in prearation, exciting electrochemical and electricalproperties. In order to optimize the performance of polyaniline electrode, in ous papers westudy the effect of qusternary ammonium surfactants [CnH_2n+1N（CH₃）₃]Cl （n=12,14,16,18）on the electrochemical synthesis of polyaniline was carried out under cyclovoltammetricconditions in sulfuric acid electrolyte. We analyzed the electrochemical behavior, structureand morphology of the products. Then polyaniline electrode doped with quaternaryammonium tetrachlorometallate [C₁₈H₃₇N（CH₃）₃]₂MCl₄（M=Co, Mn, Ni, Cu） was carriedout. We analyzed the electrochemical behavior, structure and morphology of the products andfound the best capacitive performance of polyaniline electrode doped with[C₁₈H₃₇N（CH₃）₃]₂MCl₄. By using dense stainless steel net as fluid collection, we studied thecapacitive properties of polyaniline electrode doped with [C₁₈H₃₇N（CH₃）₃]₂MCl₄. The maincontents are as follows:（1） Polyaniline electrode containing qusternary ammonium surfactants[CnH_2n+1N（CH₃）₃]Cl （n=12,14,16,18） was carried out under cyclovoltammetric condition.The surface morphology and the structures of composite electrodes were characterized byscanning electron microscopy （SEM）, fourier transform infrared spectroscopy（FTIR） andX-ray diffraction （XRD）. The electrochemical properties of electrodes and the capacitivebehavior of the resulting capacitors were systematically studied using cyclic voltammetry（CV）, ac impedance （EIS） and constant current charge–discharge tests. The results show that,compared with other surfactants, capacitive performance of polyaniline electrode doped with[C18H37N（CH3）3]Cl is better. （2） Polyaniline electrode doped with quaternary ammonium tetrachlorometallate[C₁₈H₃₇N（CH₃）₃]₂MCl₄（M=Co, Mn, Ni, Cu） was carried out under cyclic voltammogramsconditions. Cyclic voltammetry curves shows that the electrode of polyaniline doped with[C₁₈H₃₇N（CH₃）₃]₂MCl₄is obviously different to polyaniline electrode doped with[C₁₈H₃₇N（CH₃）₃]₂MCl₄（M=Ni, Mn, Co） in both the shape of oxidation-reduction peaks andthe first anodic peak current. Moreover, a particular phenomenon, i.e., a current plus wasobserved on the I-E curve of polyaniline electrode doped with [C₁₈H₃₇N（CH₃）₃]₂MCl₄for thefirst oxidation peak. The charge–discharge test results indicated that, polyaniline electrodedoped with [C₁₈H₃₇N（CH₃）₃]₂MCl₄have the highest specific capacitance.（3） Redox supercapacitors using polyaniline doped with [C₁₈H₃₇N（CH₃）₃]₂MCl₄coated,stainless steel net electrodes have been assembled and characterized. The result s indicatedthat the polyaniline electrode that doped with [C₁₈H₃₇N（CH₃）₃]₂MCl₄had higher capacity andbetter cycle performance when the current was2mA, voltage range was0⁰.6V. Then thecharge–discharge cycling test was carried out in the acidic electrolyte. The decay ofcapacitance between5³0th cycles was sight.