High Performance Supercapacitor Electrode Materials from Electrospun Carbon Nanofibers in Situ Activated by High Decomposition Temperature Polymer

Abstract

Most previous works on in situ activation of electrospun carbon nanofibers have usually used a sacrificing polymer with a low decomposition temperature (e.g., less than 300 °C) as an activation agent, which leads to limited mesoporous structure and surface area in the carbon nanofibers. In this study, we have prepared carbon nanofibers by carbonization of electrospun polyacrylonitrile (PAN) in the presence of a high decomposition temperature polymer, polysulfone (PSF), which is homogeneously blended with PAN. The use of PSF as in situ activation agent largely increased mesopore content, specific surface area, graphitization degree, interfiber connection, and conductivity in the carbon nanofibers. The PAN/PSF ratio showed an effect on these properties, and 20% PSF within the precursor nanofibers (based on the polymer weight) had the best results. When using the PAN/PSF derived carbon nanofibers as an electrode material, the prepared supercapacitor showed a specific capacitance as high as 289 F/g at the scan rate of 10 mV/s and 257 F/g at the current density of 0.25 A/g. The device had excellent cycling stability (100% capacitance retention after 6000 cycles) and large energy capability (∼36 Wh/kg). Carbon nanofibers activated with PSF may serve as a high performance electrode material for supercapacitor applications.

Improving Supercapacitance of Electrospun Carbon Nanofibers through Increasing Micropores and Microporous Surface Area

“…However, no apparent melting point was observed for PMMA though the literature reported melting point for PMMA was in the range of 220–240 °C . In our previous paper, we have elucidated that polymer activation agent with high melting point facilitate to formation of porous structure within carbon nanofibers . The higher melting point for HAS could be an important reason for the formation of more pores within CNF‐HAS.…”

“…The weight ratio was employed because of the easy implementation during experiment. The ratio 4:1 was obtained based on our previous work . A purpose‐built electrospinning machine was used to process the polymer solutions into nanofibers.…”

“…Several methods have been reported to activate electrospun carbon nanofibers, such as incorporation of low carbon‐yield polymers (e.g., poly(methyl methacrylate) (PMMA) or poly(vinylpyrrolidone) (PVP)), inorganic filler (e.g., ZnCl 2 ), or organic–inorganic hybrid (e.g., phenylsilane) into nanofiber precursor through coelectrospinning, surface treatment of CNFs with an alkaline solution (e.g., KOH) followed by heat treatment at a high temperature, or high temperature etching with a special gas (e.g., CO 2 , H 2 O) . The first method, also referred to as “in situ activation” in some papers, is more advantageous because the activation agent is directly added to PAN solution for electrospinning and hence it does not require extra process and facility. The pore size and porosity could be controlled through polymer type and its content in the precursor.…”

“…Lai and Lo prepared porous carbon nanofibers and hollow carbon nanofibers respectively using low molecular weight and high molecular weight PMMA as additive, and indicated that the porous carbon nanofibers showed better electrochemical performance than hollow carbon nanofibers. Wang et al from our group reported the preparation of highly porous carbon nanofiber using polysulfone (PSF), a high decomposition temperature polymer, as in situ activation agent. The PSF activated carbon nanofibers showed considerable increase in mesopore content, specific surface area, graphitization degree, conductivity, and EDLC electrode capacitance.…”

Multilayer carbon materials prepared from Zanthoxylum schinifolium husk for high-performance supercapacitors

“…15 Therefore, the preparation of biomass-based carbon materials with more connected channels and more active functional groups has been an important research direction. 16,17 Herein, porous carbon having abundant nitrogen functional groups is prepared by KOH activation in a tube furnace. The raw material Zanthoxylum schinifolium husk (ZSH) is easy to obtain and has a high heteroatom content; thus, it is a promising raw material for producing nitrogen-rich porous carbon.…”