Beyond Slurry-Cast Supercapacitor Electrodes: PAN/MWNT Heteromat-Mediated Ultrahigh Capacitance Electrode Sheets

Jung Han Lee,Sang-Young Lee,Sun-Hwa Yeon,Sun-Young Lee,Jeong A Kim,Ju-Myung Kim

doi:10.1038/srep41708

Abstract

Supercapacitors (SCs) have garnered considerable attention as an appealing power source for forthcoming smart energy era. An ultimate challenge facing the SCs is the acquisition of higher energy density without impairing their other electrochemical properties. Herein, we demonstrate a new class of polyacrylonitrile (PAN)/multi-walled carbon tube (MWNT) heteromat-mediated ultrahigh capacitance electrode sheets as an unusual electrode architecture strategy to address the aforementioned issue. Vanadium pentoxide (V2O5) is chosen as a model electrode material to explore the feasibility of the suggested concept. The heteromat V2O5 electrode sheets are produced through one-pot fabrication based on concurrent electrospraying (for V2O5 precursor/MWNT) and electrospinning (for PAN nanofiber) followed by calcination, leading to compact packing of V2O5 materials in intimate contact with MWNTs and PAN nanofibers. As a consequence, the heteromat V2O5 electrode sheets offer three-dimensionally bicontinuous electron (arising from MWNT networks)/ion (from spatially reticulated interstitial voids to be filled with liquid electrolytes) conduction pathways, thereby facilitating redox reaction kinetics of V2O5 materials. In addition, elimination of heavy metallic foil current collectors, in combination with the dense packing of V2O5 materials, significantly increases (electrode sheet-based) specific capacitances far beyond those accessible with conventional slurry-cast electrodes.

Highlights

Is the removal of heavy metallic current collectors in the electrodes
The self-standing, metallic foil current collector-free heteromat V2O5 electrode sheets were produced through the concurrent electrospraying (for V2O5 precursor (=VOC2O4)/multi-walled carbon tube (MWNT)) and electrospinning followed by calcination in air
The spatially reticulated interstitial void channels, in combination with the polar PAN nanofibers, facilitated capillary intrusion of liquid electrolyte (=2 M KCl aqueous electrolyte) into the V-250 and V-300 electrode sheets (Supplementary Fig. S4b), indicating the better electrolyte accessibility. These results demonstrate that the PAN/MWNT heteronanomat-mediated architecture of the V-250 and V-300 electrode sheets allowed for the construction of highly interconnected dual conduction pathways, which is expected to boost up Faradaic redox reaction kinetics

Summary

Introduction

A number of studies have been reported for the development of metallic foil current collector-free electrodes for SCs11,18,19 and lithium-ion batteries[20,21,22,23]. Most of these previous works have combined electrode materials with pre-formed three-dimensional (3D) porous scaffolds, resulting in low active-mass loading per unit electrode area. We present a new class of metallic foil current collector-free, polyacrylonitrile (PAN)/multi-walled carbon tube (MWNT) heteromat-mediated ultrahigh capacitance electrode sheets as an unusual electrode architecture strategy to address the aforementioned long-standing challenge of SC electrodes. The removal of heavy metallic foil current collectors, in association with compact packing of V2O5 materials, enables a remarkable increase in (electrode sheet-based) specific capacitances, which lie far beyond those achievable with conventional slurry-cast electrodes

Methods

Results

Conclusion