Preparation And Properties Of Polyaniline/TiO₂ Nanotube Arrays Composite Electrodes

Supercapacitors are energy storage devices with both high energy density and high power density,and electrode is the most important part of supercapacitors.In this work,polyaniline-TiO₂ nanotube arrays composite electrodes were prepared by three different methods.Morphologies and structures of the composite electrodes were characterized by scanning electron microscopy,X-ray diffraction,infrared spectroscopy and X-ray energy dispersive spectrometer,respectively.The electrochemical properties of the composite electrodes were tested by electrochemical workstation,and the effects of preparation conditions on the samples'morphologies and electrochemical properties were studied.The composite electrodes were prepared by depositing the polyaniline onto the TiO₂ nanotube arrays obtained by anodic oxidation using cyclic voltammetry method.The effects of oxidation electrolyte proportion,oxidation voltage,oxidation time,calcination temperature,monomer solvent,aniline concentration,deposition scan rate and deposition time of polyaniline on the morphologies and electrochemical properties of composite electrodes were studied.We summarized the optimal conditions on fabricating the composite electrodes and tested the performance of the optimum sample.The optimized composite electrode exhibited excellent electrochemical performance in sodium sulfate aqueous solution with a large working potential window of-0.2-1.8 V and an energy density of 727.3 J·g^-1 at 0.05 m A·cm^-2.After 5000 cycles,the capacitance retention of the composite electrode was 96.3%.An in-situ microcavity polymerization method was adopted to fabricate the polyaniline-TiO₂ nanotube arrays composite electrodes.The effects of monomer solvents,aniline concentration and ammonium persulfate concentration on the morphologies and properties of the samples were studied.The preparation conditions of composite electrodes were optimized,and the performance of the samples were studied.The properties of the optimized composite electrode in sulfuric acid aqueous solution was better than that in sodium sulfate aqueous solution.The composite electrode showed a wide working potential window of-0.2-1.8 V,a large specific capacitance of 816.7 F·g^-1 and a high energy density of 1410.8 J·g^-1.The capacitance retention of the composite electrode could be retained at 95%when the current density increased from 0.1 to 5 m A·cm^-2,and its capacitance retention was over 97%after 5000 cycles.In order to simplify the preparation process of polyaniline-TiO₂ nanotube arrays composite electrodes and further improve the performance of the electrodes,a new way,one-step anodic oxidation method,was employed to prepare the composite electrode.The morphologies and properties of the composite electrodes were studied,and the results showed that the composite electrodes obtained by one-step anodic oxidation method exhibited wonderful stability both in sodium sulfate and sulfuric acid electrolytes.The capacitance retention of the composite electrode were all over96%after 10000 cycles at the potential window of-0.2-1 V and-0.2-1.8 V.