Layer-by-Layer modification of graphite felt with MWCNT for vanadium redox flow battery Articles uri icon

publication date

  • January 2019

start page

  • 131

end page

  • 140

volume

  • 313

International Standard Serial Number (ISSN)

  • 0013-4686

Electronic International Standard Serial Number (EISSN)

  • 1873-3859

abstract

  • Layer-by-Layer (LbL)deposition of multi-walled carbon nanotubes (MWCNT)was used to modify porous electrodes for vanadium redox flow batteries. Preliminary studies performed over glassy carbon (GC)electrodes showed that assemblies obtained with MWCNT displayed better mechanical stability than those prepared with other carbon nanoforms. The LbL process involved successive deposition of the polyethylenimine (PEI)and carbon nanotubes dispersed with poly(acrylic acid)(PAA). The thickness of the MWCNT assembly deposited onto a GC strongly influenced the electrochemistry of VO2 +/VO2+ species. The thicker the film, the better the electrochemical reversibility resulted. An apparent electron transfer rate constant kapp of 5 × 10¿4 cm s¿1 was determined for a glassy carbon electrode modified with one hundred bi-layers and treated at 650 °C in inert atmosphere. The LbL technique was applied to the modification of graphite felt (GF)electrodes. GF electrodes modified with ten bilayers of PEI-PAA(MWCNT)were tested in a vanadium redox flow battery, showing a net decrease in the charge and discharge overpotentials with respect to the unmodified graphite felt. Lower overpotentials for charge-discharge resulted in higher energy and voltage efficiencies for the battery with modified GF electrodes. Furthermore, cyclability of the system was tested and no fading was observed in the battery performance after one hundred cycles. © 2019 Elsevier Ltd

keywords

  • carbon electrodes carbon nanotubes graphite felt layer-by-layer deposition vanadium redox flow battery carbon nanotubes deposition electric discharges felt felts flow batteries glass glass membrane electrodes graphite graphite electrodes mechanical stability nanotubes rate constants vanadium dioxide yarn carbon electrode electrochemical reversibility electron-transfer rate constants glassy carbon electrodes graphite felts layer by layer deposition successive depositions vanadium redox flow batteries multiwalled carbon nanotubes (mwcn)