| Flexible supercapacitors have potential applications in various fields such as flexible sensors and triboelectric nanogenerators.The flexible supercapacitor based on polypyrrole conductive paper has the potential of high theoretical specific capacitance and low cost,and has become a research hotspot around the world.However,the polypyrrole conductive paper still has bottleneck problems of uneven load,low mass loading and poor mechanical strength,which greatly restricts its application in flexible supercapacitors.The solution of the above problems is of great significance for promoting the application of polypyrrole conductive paper in flexible supercapacitors and promoting the development of flexible supercapacitors in the direction of high performance,low cost and green.In this paper,in-situ self-assembly technology is used to prepare polypyrrole conductive paper,and the load uniformity,load capacity and mechanical properties of polypyrrole conductive paper are improved by adjusting the internal structure of the paper and modifying the paper with high polymerization degree fiber.First,the paper is impregnated with regenerated cellulose solution,and a film-like structure is formed between the paper fibers by freeze drying,giving more loading sites inside the paper,combined with the absorbent paper liquid absorption technology to achieve the uniformity of polypyrrole on the fiber surface Increase in load and load.On this basis,adding high-polymerization fiber as the reinforcing fiber to the paper not only improves the mechanical properties of polypyrrole conductive paper,but also retains excellent electrical properties.The microstructure and physicochemical properties of polypyrrole conductive paper were characterized by FT-IR,SEM,four-probe testing,electrochemical testing and other testing techniques.Using the prepared polypyrrole conductive paper as an electrode to assemble a solid supercapacitor,the performance of the supercapacitor was studied.The main research conclusions are as follows:?1?To solve the problem of low mass loading and uneven loading of polypyrrole,this thesis used regenerated cellulose to impregnate the paper and make it precipitate between the pores of the paper,giving polypyrrole more loading sites.And used negative pressure suction technology to promote the penetration of oxidants into the paper.Compared with the untreated samples,the conductivity of the treated conductive paper was increased by 129%and the capacitance was increased by 81%.The polypyrrole was evenly loaded on the inner and outer fiber surfaces of the paper.Then further explored the influence of the concentration and degree of polymerization?DP?of regenerated cellulose on the performance of polypyrrole conductive paper,and obtained the best preparation process of polypyrrole conductive paper.As the concentration of regenerated cellulose increases,the electrochemical performance of polypyrrole conductive paper increases first and then decreases,while the mechanical properties are positively correlated with the change in the concentration of regenerated cellulose;the increase in the DP of regenerated cellulose can improve the electrochemical and mechanical properties of polypyrrole conductive paper.The optimal concentration obtained in this thesis is0.59 wt%,the DP is 266,whose conductivity reaches 4.35 S?cm-1,and maximum specific capacitance is 2984 m F?cm-2.The assembled flexible supercapacitor has a maximum specific capacitance of 1127 m F?cm-2,and the highest energy density and highest power density are 106?Wh?cm-2 and 3.49 m W?cm-2,respectively.?2?To solve the problem of low mechanical strength of polypyrrole conductive paper,this thesis uses self-made fibers as reinforcing fibers,which improves the mechanical properties of the paper while hardly affecting the electrochemical performance of polypyrrole conductive paper.The tensile strength of the paper made by self-made fiber paper is 37.9 MPa,and the corresponding polypyrrole conductive paper is 22.7 MPa,which is 103%higher than that of original paper.The maximum specific capacitance of the assembled flexible supercapacitor can reach 781 m F?cm-2,and the maximum energy density and maximum power density are 64?Wh?cm-2 and 1.89 m W?cm-2,respectively.It is proved that the use of self-made fibers can improve the mechanical strength of polypyrrole conductive paper and produce high-strength and high-performance flexible polypyrrole solid supercapacitors without affecting the capacitive performance of polypyrrole conductive paper. |
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