A Study On The Design And Electrochemical Performance Of Polypyrrole-based Flexible Supercapacitors

Portable and wearable supercapacitor devices have been designed and developed for various application scenarios,including in smart surfaces and wearables devices.Polypyrrole(PPy)is one of conducting polymers,which have been widely exploited as the electrode materials for flexible supercapacitors because of their inherent elastomeric properties,high electrical conductivity,and good electrochemical redox reversibility.Such a material can efficiently offer additional energy storage capacity.In this study,we focus on the synthesis and the application of PPy and its carbonized materials in supercapacitors.The main achievements are as follows:First,we studied a flexible polypyrrole film electrode synthesized by a modified versatile vapor-phase polymerization(VPP)strategy.Differing from conventional VPP protocols that are likely to form smooth polymer films,it could easily engineer the PPy film with porous and interconnected structure by simply optimizing the concentration of oxidant,the polymerization time and the cleaning solution.The film electrode showed an exceptionally high electrical conductivity up to 94 S cm^-1.The unique porous PPy films constructed by interconnected electronic/ionic conductive networks achieved a specific capacitance of 494 F g^-1 at a current density of 1 A g^-1.Obviously,the electrochemical performance of our PPy electrode materials is significantly better compared to other reported PPy-based materials,due to the synergistic effect of superior conductance and the porous architecture.In order to further evaluate the practical potential of the porous PPy films based supercapacitors,we have conducted the correlated electrochemical measurement.The results indicated that the fabricated all-solid-state supercapacitor device with the PPy electrodes exhibited a specific capacitance of 332.5 F g^-1with high power density and energy density of 403 Wh kg^-1 and29.56 k W kg^-1respectively.Due to the exceptionally high electrical conductivity and ion-accessibility,the solid-state symmetrical supercapacitor devices assembled by PPy electrode materials have not only outstanding electrochemical performance,but also superior flexibility under various deformations.The all-solid-state device has the ability to effectively light up LEDs,which offers a new vision for flexible energy storage.As a nitrogen-rich material,polypyrrole can be pyrolyzed into a nitrogen-doped carbonaceous materials with a nitrogen content up to 10.87%.We have evaluated the structure and the electrochemical behaviors for this material.It has been found that different activation agents such as Zn Cl₂ and KOH have a great effect on the morphology and electrochemical properties of polypyrrole.The electrochemical characterization showed that the carbon activated by Zn Cl₂ achieves has a specific capacitance of 364 F g^-1 at 1 A g^-1,which displays a better cyclic stability and higher specific capacitance.With the help of XPS and other microscopic analysis methods,we found that pyridine carbon and pyrrole nitrogen can contribute more pseudocapacitance and electric double layer capacitors under acidic electrolytes.