Carbon Felt Coated with Titanium Dioxide/Carbon Black Composite as Negative Electrode for Vanadium Redox Flow Battery

Abstract

This investigation focuses on the effect of titanium dioxide (TiO 2 ) coatings of a carbon black (XC-72) negative electrode on the performance of a vanadium redox flow battery (VRFB). TiO 2 , a hydrophilic material, was added to the carbon electrode to improve the wettability and reduce the electrical resistance of the electrode surface. The electrochemical performances of homemade TiO 2 , commercial TiO 2 , and carbon felt are investigated by using cyclic voltammetry and single-cell charge-discharge measurements. An electrode with 20 wt% of fabricated TiO 2 loading at a scan rate of 0.006 V s −1 shows a specific capacitance (C s,t ) of 186.2 F g −1 , which is 55.5% and 12.2% higher than that of pure carbon electrode (119.7 F g −1 ) and commercial TiO 2 (166.0 F g −1 ), respectively. At current density of 200 mA cm −2 , the energy storage efficiency (η E = 65.4%) of the single cell with 20 wt% homemade TiO 2 /C-containing carbon felt negative electrode is 16.0% and 6.1% higher than that of the negative electrode with raw carbon felt (η E = 56.4%) and of the negative electrode containing commercial TiO 2 /C (η E = 61.6%), respectively. These results demonstrate the potential application of TiO 2 /C electrodes for high-efficiency VRFBs at high current densities. Vanadium redox flow battery (VRFB) has been proposed as a promising candidate for large scale energy storage applications, such as load-leveling applications. VRFB can store and stabilize intermittent electricity generated from wind turbine or photovoltaic. VRBF has several advantages over other types of batteries, such as excellent electrochemical reversibility, high roundtrip efficiency, flexible, and negligible cross-contamination between positive and negative electrolytes.1-5 VRFB employs V(IV)/V(V) and V(II)/V(III) redox couples as positive and negative half-cells, respectively, with the standard open circuit cell potential approximate 1.26 V at 100% state of charge. 6Carbon felt is a typical electrode material and it has wide operating electrode potential range, chemically stable, high surface area, and reasonable price. However, carbon felt electrode shows poor electrochemical activity. Therefore, much attention has been focus to electrode modification to enhance its electrochemical properties. [7][8][9][10][11][12][13][14] Several alternative electrode materials have been proposed to improve electrode performance, such as metal electrodeposition on carbon fibers. Various metal compounds have also been deposited on graphite fibers to improve the catalytic activity for vanadium redox couples and to enhance electrode stability in acidic vanadium solution. In the literature, metal compounds deposited on carbon felts include IrO 2, 9 Ru(O 2 ), 10 and Ir, 11 whereas others include partial modification of the functional groups on the graphite surface.12,13 The coating of metal nanoparticles on the fiber of carbon felt is a promising approach. Recently, transition metal oxides, e.g. TiO 2 , ZnO, have been studied extensively as a water adsorbent for improv...

Hydrogen‐Treated Rutile TiO2 Shell in Graphite‐Core Structure as a Negative Electrode for High‐Performance Vanadium Redox Flow Batteries

“…[24,25] In this scenario, TiO 2 is au seful materialf or photocatalysis, [26] gas sensors, [27][28][29] Li-ion batteries, [30,31] and catalysis. [34][35][36] Ts eng et al [37,38] explored the effect of the anatase-TiO 2 nanoparticles deposited on carbon black as an egative electrode in VRFBs. Over the past decade, DFT predictions, in conjunction with experimental efforts, have played an important role in designing electrocatalysts.…”

“…TiO 2 dramatically reduces the HER rate by several orders of magnitude. [34][35][36] Ts eng et al [37,38] explored the effect of the anatase-TiO 2 nanoparticles deposited on carbon black as an egative electrode in VRFBs. Owing to the partial reduction of HER activity that was obtained, the electrocatalyst containing TiO 2 nanoparticlese xhibitede xcellent resultsi nc omparison with commercial electrodese ven at high current densities.…”

Titanium as a Substrate for Three‐Dimensional Hybrid Electrodes for Vanadium Redox Flow Battery Applications

“…For VRFBs, carbon-based electrodes based on graphite felts [5] meet most requirements including high electrical conductivity (at least under compression), availability and price. [6] However, it was also shown that this standard electrode material (carbon felt/carbon nonwoven) has to be activated in order to provide an acceptable catalytic activity for vanadium ion redox conversion, [7] and even in this case further improvement is desired to overcome kinetic limitations, as detailed above.…”

Aligned Electrospun Carbon Nanofibers as Electrodes for Vanadium Redox Flow Batteries

“…However, the performance is less than satisfactory due to the poor electrochemical activity and low surface area of the electrodes, which will cause high polarization loss on the charge/discharge processes during battery operations . To tackle this problem, various approaches including surface treatment and depositing catalysts have been proposed to improve the activity and specific surface area of the electrodes . Nevertheless, a majority of the surface modifications were conducted under elevated temperature or chemical baths by introducing strong acids and alkalis (HNO 3 , H 2 SO 4 , KOH) .…”