Solid-state supercapacitor cell based on 3D nanostructured MnO2/CNT microelectrode array on graphite and H3PO4/PVA electrolyte

摘要

Rapid development of portable consumer electronics has promoted the need for lightweight, flexible, environmentally friendly, high safety, and highly efficient energy storage technology. Herein, we present the fabrication and characterization of three dimensional (3D) nanostructured supercapacitor microelectrode arrays using manganese dioxide and carbon nanotubes (MnO2/CNTs) on graphite foil substrate and polyvinyl alcohol (PVA)/phosphoric acid (H3PO4) solid polymer electrolyte for integration into a solid-state supercapacitor cell, without any additives or binders. A low-cost, hot filament chemical vapor deposition (HFCVD) process was used to synthesize vertically aligned 3D CNT microelectrode arrays, which act as the current conductors, directly on a flexible, conducting graphitefoil current collector. Thin-film MnO2 deposition on the CNTs was achieved by an electrochemical technique using in-situ reduction of MMnO4, without any supporting electrolyte, which provides excellent bonding between the two for enhanced stability. Electrochemical characterization in aqueous electrolyte (KCI) yielded capacitance of 721 mF or 858 F.g(-1) at I mV.s(-1) scan rate. After assembling the solid-state supercapacitor cell, we obtained nearly 1.4 F or 830 F.g(-1) at 1 mV.s(-1) in a symmetric configuration. Maximum specific power value of 73.9 kW.kg(-1) land a maximum specific energy of 1152 Wh.kg(-1) was achieved. The solid-state device exhibits excellent cycling stability with a capacitance loss of only 11% after 3000 cycles. Detailed fabrication and characterization results have been presented. (C) 2017 Elsevier B.V. All rights reserved.