Beyond slurry-cast supercapacitor electrodes: PAN/MWNT heteromat-mediated ultrahigh capacitance electrode sheets

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.