Abstract
Improving the electrochemical activity of electrodes is essential to the development of vanadium redox flow battery (VRFB). In this work, we prepared a novel electrode with the modification of nitrogen-doped carboxyl multiwalled carbon nanotubes using dopamine as an eco-friendly nitrogen source (carboxyl MWCNT@PDAt). Characterization and electrochemical measurements reveal that the synthesized carboxyl MWCNT@PDAt-modified graphite felt electrode (carboxyl MWCNT@PDAt/GF) exhibits excellent electrochemical performance toward VO2+/ reaction. Superior battery performance was obtained with the energy efficiency of 80.54% at a current density of 80 mA cm−2. Excellent durability of the carboxyl MWCNT@PDAt/GF electrode was confirmed by long-term charge/discharge tests. The enhanced reaction kinetics of VO2+/ is ascribed to the synergetic effect of oxygen and nitrogen containing groups on graphite felt surface and the presence of nitrogen-doped carboxyl multiwalled carbon nanotubes (MWCNT). The facile approach proposed in this paper provides a new route to the fabrication of electrode with excellent performance for VRFB.
Highlights
Renewable energies, including hydroenergy, geothermal energy and solar energy, have drawn great attention owing to the growing energy demand and environmental hazards
The graphite or carbon felts suffer from the problems of low electrochemical activity, which impedes the enhancement of the energy efficiency and capacity of vanadium redox flow battery (VRFB), making it difficult to meet the demands of energy storage system [6]
The surface morphology of carboxyl multiwalled carbon nanotubes (MWCNT)@PDAt-900/graphite felt (GF) was characterized by scanning electron microscope (SEM)
Summary
Renewable energies, including hydroenergy, geothermal energy and solar energy, have drawn great attention owing to the growing energy demand and environmental hazards. Carbon-based electrodes, taking the advantages of long cycle life under acidic solution, high conductivity and low cost for commercial application, have been widely investigated in the VRFB area over the past few decades [4]. Carbon nanotubes (CNTs) have drawn a great deal of attention in VRFB area due to their high electrical conductivity, superior chemical stability in acid solution and high specific surface area [3,21,22]. Toxic reagents are usually required, which limits the wide application of nitrogen-doped CNTs. Dopamine, which is non-toxic, has shown versatile coating capabilities on surface of various materials, yielding high concentration of amine groups [30,31]. A facile and practical process for the fabrication of graphite felt (GF) with nitrogen doping and oxygen containing groups modification remains a priority in the development of VRFB. Charge/discharge measurements were conducted to evaluate the efficiency and stability of carboxyl MWCNT@PDAt/GF in acid solution
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