Preparation Of Hybrid Polyaniline Composites And Their Application In Supercapacitors

Supercapacitors have attracted significant attention due to their fast charge and discharge rate,high power density and long cycle life.Polyaniline（PANI）is a promising conducting polymer in the energy storage field due to its abundant resources,high specific capacitance and high electron conductivity.However,pure PANI suffers from poor cycling stability,which restricts its application as an electrode material in supercapacitor.In order to improve its electrochemical performance,PANI is usually compounded with other materials or prepared with special microstructure.In this work,PANI is employed to prepare cross-linked PANI hydrogel composites.The responding results of this work are listed as follows:（1）MnO₂ nanomaterials with different morphologies were prepared by emulsion method and hydrothermal method.Their structures,morphologies and electrochemical properties were tested.As a result,MnO₂ nanospheres with a diameter of about 120 nm were synthesized by emulsion method.MnO₂ nanorods and nanowires with a diameter of about 30 nm were synthesized by hydrothermal method.It has good electrochemical performance in alkaline and neutral electrolytes,but MnO₂ was decomposed in acid electrolyte.（2）MnO₂/PANI composites were prepared by in-situ polymerization using MnO₂as template and co-oxidant.The results showed that the morphological structure of MnO₂/PANI could be controlled according to different morphologies of MnO₂.MnO₂/PANI composites displayed a higher specific capacitance.The specific capacitances of NRs-MP1:1,NPs-MP1:1 and NWs-MP1:1 were 383.6 F/g,425.0 F/g and 368.9 F/g,respectively.After the NPs-MP1:1 was employed to assemble a symmetric supercapacitor,its power density reached 5 kW/kg and energy density was about 10.69 Wh/kg.After 1000 cycles,the specific capacitance still remained 78.38%.（3）PVA-PANI,PVA-PANI-MnO₂ and PVA-PANI-CNT hydrogel composite electrode materials were prepared by using 3-aminobenzeneboronic acid as molecular cross-linking agent.After the electrochemical tests,the results showed that PVA-PANI was a three-dimensional porous structure composed of nanosheets.The structure of PVA-PANI-MnO₂ and PVA-PANI-CNT became a three-dimensional network with abundant porous structure.The concentration of 3-aminobenzeneboronic acid had great effect on the electrochemical performance of different samples.As a result,PVA-PANI-MnO₂-0.05 had the highest specific capacitance of 675.0 F/g.The electrochemical performance of PVA-PANI-CNT with different CNT content was also tested.PVA-PANI-CNT40 showed the best electrochemical performance and its specific capacity reached 471.3 F/g.Furthermore,in the condition of ultra-high rate for charge or discharge,its capacitor still kept 71.6%at 50.0 A/g.In addition,after the PVA-PANI-CNT40 was assembled into a symmetrical supercapacitor,its power density reached 12kW/kg and its energy density was about 7.33 Wh/kg.After 1000 cycles,the specific capacitance still remained 83.78%.