Polyacrylonitrile/polyvinyl alcohol‐based porous carbon nanofiber electrodes for supercapacitor applications

Abstract

Summary Porous carbon nanofibers (PCNFs) were produced from polyacrylonitrile (PAN)/polyvinyl alcohol (PVA) hybrid nanofibers with different mixing ratios and used as the free‐standing, flexible, high performance electrodes for the supercapacitors. The effect of PAN/PVA ratio, PVA removing and stabilization/carbonization process on the chemical structure, and the morphology of PAN/PVA hybrid nanofibers and PCNF were investigated by Fourier transform infrared (FT‐IR), field emission scanning electron microscopy (FE‐SEM), and thermogravimetric analyzer (TGA). It was proved by FT‐IR and FE‐SEM analyses that PAN/PVA hybrid nanofibers are successfully produced and carbonized. In addition, the electrochemical performance of PCNF electrodes was analyzed by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) methods. Results showed that PCNFs exhibit higher specific capacitance and better electrochemical performance than neat carbon nanofibers (N‐CNF). The specific capacitance of the EK5 PCNF (67/33 PAN/PVA wt ratio) was 157 F/g at 5 mV/s scan rate in 1 M H2SO4, while the specific capacitance of N‐CNF was 96 F/g at the same conditions. Moreover, the PCNF showed excellent cyclic stability without losing performance through 2500 charge/discharge cycles at a current density of 2 A/g. As a result, free‐standing, flexible, and high‐performance PCNFs are excellent candidates as supercapacitor electrodes for flexible energy‐storage devices.

Flexible carbon nanofiber yarn electrodes for self-standing fiber supercapacitors

“…Our previous method 54,55 was followed and a new method was presented here to produce carbon nanofiber yarn. After obtained PAN nanofiber yarns wound around the glass beaker and fixed them at the ends, they were heated to 300°C at a heating rate of 10 ⁰C/min in an air environment and then, stabilized for 90 min at 300°C.…”

“…To begin, a 1.5 cm wide and 300 cm long aluminum foil band was wound at an angle onto the aluminum drum, followed by electrospinning 10 mL of 7.5% PAN solution in DMF:DMSO (2:1) under previously optimized conditions (17.5 cm distance, 2 mL/h feed rate, 28 kV applied voltage). 54 At the end of production, the aluminum foil band was removed from the aluminum drum and the 300-cm-long band was cut to a width of 0.5 cm. Following that, a PAN nanofiber strip with a width of 0.5 cm and a length of 300 cm was removed from the aluminum band.…”

“…The optimal conditions for the polyacrylonitrile (PAN) nanofiber production and carbonization processes study were established in our previous researches, 54,55 and in this study, homogeneous PAN nanofiber mats collected on an aluminum drum capable of being rotated at various speeds were cut to a strip with specified width and twisted into yarn. Stabilizing and carbonizing the produced PAN nanofiber yarns resulted in the formation of flexible CNFY.…”

Silver nanoparticles as a conductive bridge for high‐performance flexible all‐solid‐state asymmetric supercapacitor

“…Although the TMOs and CPCs have excellent capacitance properties, it is impractical to use directly in flexible supercapacitor because they are prone to fracture under slight strain 16,17 . Carbon‐based materials exhibit favorable mechanical strength, but the lower capacitance and electrolyte accessibility lead to poor energy density for flexible all‐solid‐state supercapacitor 18,19 . In this respect, combining carbon materials with TMOs may be an ideal strategy to prepare flexible electrode materials due to the complementation of both materials 20,21 .…”

“…16,17 Carbon-based materials exhibit favorable mechanical strength, but the lower capacitance and electrolyte accessibility lead to poor energy density for flexible all-solid-state supercapacitor. 18,19 In this respect, combining carbon materials with TMOs may be an ideal strategy to prepare flexible electrode materials due to the complementation of both materials. 20,21 Therefore, great efforts have been dedicated to maximize energy density of supercapacitors by combining both materials sufficiently.…”