Preparation And Electrochemical Properties Of Polypyrrole-Based Electrode Materials

Energy storage equipment plays a very important role in modern society.The increasingly popular portable electronic devices and electric vehicles have put forward higher requirements for the performance of energy storage devices.Supercapacitors have received extensive attention in recent years due to their high power density,long cycle life,safety and environmental protection.The electrode material is a key factor affecting the comprehensive performance of supercapacitors.Polypyrrole?PPy?,as a pseudocapacitive electrode material,has received much attention due to its high conductivity,low cost and good redox reversibility.In this paper,polypyrrole and its composites were prepared by chemical redox method and electrochemical deposition method respectively,and their morphology,structure and electrochemical properties were investigated.The main content and conclusion are as follows:?1?Polypyrrole aerogels were prepared by chemical oxidation under different conditions.The optimum preparation conditions were obtained by optical photograph combined with SEM image analysis.The mass ratio of pyrrole to ferric chloride hexahydrate is 1:1,and the concentrations of pyrrole,ferric chloride and hydrochloric acid are 50 mg/mL,50 mg/mL and0.75 mg/respectively.The polypyrrole aerogel is composed of nanosphere particles connected to each other to form a three-dimensional network structure with rich internal porosity.The specific capacitance of the polypyrrole aerogel is 140.5 F/g at a current density of 1 A/g.In addition,polypyrrole aeroge also has good rate performance.When the current density increases to 20 A/g,the specific capacitance of the polypyrrole aerogel electrode is90.4 F/g.?2?Graphite phase carbon nitride?g-C₃N₄?nanosheets,prepared with melamine,mixed with pyrrole and oxidant to prepare g-C₃N₄@PPy aerogels.The g-C₃N₄@PPy aerogels not only maintain the morphology of the porous network of polypyrrole aerogels,but also have layered g-C₃N₄ nanosheets.When the current density is 1A/g,the specific capacitance of g-C₃N₄@PPy electrode is 564.6 F/g,which is significantly higher than that of PPy electrode?140.5F/g?.The introduction of g-C₃N₄ increases the nitrogen content.Therefore,the electronic donor performance and wettability of the material are improved,and the efficiency of ion and electron transport is enhanced.Combined with the larger pseudocapacitance provided by polypyrrole,the comprehensive electrochemical performance of the electrode was effectively improved.The g-C₃N₄@PPy electrode and activated carbon electrode were assembled to form a buckled supercapacitor.When the power density was 600 W/kg,the energy density was 11.4 Wh/kg.?3?Polypyrrole films were prepared on nickel foam by different methods under different electrolyte conditions.When dilute sulfuric acid is used as supporting electrolyte,the performance of the PPy-S2 film prepared by two-phase electrochemical deposition is the best.The morphology of PPy-S2 is similar to the surface of balsam pear,with a large number of serrated structure,which enlarges the specific surface area.However,the surface of the sample?PPy-S1?prepared by single-phase method with dilute sulfuric acid as electrolyte is spherical aggregated structure with smaller specific surface area.The specific capacities of PPy-S2 and PPy-S1 electrodes at 1 A/g are773.6 F/g and 266.4 F/g,respectively.After 1000cycles at a current density of 5 A/g,the capacity retention rate of PPy-S2 electrode is 90.3%.