High-performance hybrid capacitor based on a porous polypyrrole/reduced graphene oxide composite and a redox-active electrolyte

Oxidative MnO2 Template Assisted Electrochemical Fabrication of Graphene/Polypyrrole Supercapacitor Electrodes

Improving the morphological structure of active materials is a reliable strategy for the fabrication of high-performance supercapacitor electrodes. In this study, we introduce a feasible approach to constructing the graphene/polypyrrole (PPy) composite film implanted onto the current collector through a two-step electrochemical deposition method utilizing MnO2 as an intermediary template. The reduced graphene oxide (rGO) hydrogel film is first hydrothermally grown on a carbon cloth (CC) substrate to obtain a porous rGO@CC electrode on which MnO2 is electrodeposited. Then the as-prepared rGO/MnO2@CC electrode is subjected to the electrochemical polymerization of pyrrole, with MnO2 acting as an oxidizing template to facilitate the oxidative polymerization of pyrrole, ultimately yielding an rGO/PPy composite film on CC. The PPy synthesized via this methodology exhibits a distinctive interconnected structure, resulting in superior electrochemical performance compared with the electrode with PPy directly electrodeposited on rGO@CC. The optimized electrode achieves an impressive specific capacitance of 583.6 F g-1 at 1 A g-1 and retains 83% of its capacitance at 20 A g-1, with a capacitance loss of only 9.5% after 5000 charge-discharge cycles. The corresponding all-solid-state supercapacitor could provide a high energy density of 22.5 Wh kg-1 and a power density of 4.6 kW kg-1, with a capacitance retention of 82.7% after 5000 charge-discharge cycles. Furthermore, the device also demonstrates good flexibility performance upon bending at 90 and 180°. This work presents an innovative method for the preparation of carbon material/conducting polymer electrodes with specific structural characteristics and superior performance.

In-situ composited g-C3N4/polypyrrole nanomaterial applied as energy-storing electrode with ameliorated super-capacitive performance

Graphitic carbon nitride (g-C3N4) and polypyrrole (ppy) nanocomposites are synthesized and cast off as material for electrodes intended for energy storage, where the amount of pyrrole is being kept static after optimization by altering the amount of g-C3N4 to make a series of g-C3N4/ppy (pcn) nanocomposites. These nanocomposites are successfully synthesized by employing in-situ oxidation polymerization by oxidizing pyrrole. The nanocomposites are further characterized by Fourier transform infrared spectroscopy (FT-IR) for structural investigation, thermal gravimetric analysis (TGA) for thermal stability analysis, and field emission scanning electron microscopy (FESEM) and transmission electron microscopy (HR-TEM) for surface morphological scrutiny. The electrochemical measurements of the series are inspected with the help of galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) measurements. It is detected that 0.4 pcn has the highest specific capacitance value of 555 F g-1 at 10 mV s-1 scan rate through CV and 475 F g-1 at a current density of 0.5 A g-1 through GCD in 1 M H2SO4 in contrast with neat g-C3N4 as well as ppy where both the precursors have this value below 100 F g-1. This composite exhibited good cyclic stability with high retention. The high energy density of 0.4 pcn composite is analyzed at 86 Wh/kg at a power density of 300 W/kg. Due to facile synthesis, significant specific capacitance, and excellent energy density, pcn is a promising candidate for its application in energy storage purposes.

One-step and room-temperature fabrication of carbon nanocomposites including Ni nanoparticles for supercapacitor electrodes

With the increasing importance of power storage devices, demand for the development of supercapacitors possessing both rapid reversible chargeability and high energy density is accelerating. Here we propose a simple process for the room temperature fabrication of pseudocapacitor electrodes consisting of a faradaic redox reaction layer on a metallic electrode with an enhanced surface area. As a model metallic electrode, an Au foil was irradiated with Ar⁺ ions with a simultaneous supply of C and Ni at room temperature, resulting in fine metallic Ni nanoparticles dispersed in the carbon matrix with local graphitization on the ion-induced roughened Au surface. A carbon layer including fine Ni nanoparticles acted as an excellent faradaic redox reaction layer and the roughened surface contributed to an increase in surface area. The fabricated electrode, which included only 14 μg cm⁻² of Ni, showed a stored charge ability three times as large as that of the bulky Ni foil. Thus, it is believed that a carbon layer including Ni nanoparticles fabricated on the charge collective electrode with an ion-irradiation method is promising for the development of supercapacitors from the viewpoints of the reduced use of rare metal and excellent supercapacitor performance.

The charge collective electrode with faradaic redox reactor consisting of carbon nanocomposite including Ni nanoparticles is promising for the supercapacitor electrode.