Hybrid Electrospun Nanofibers as Electrocatalyst for Vanadium Redox Flow Batteries: Theory and Experiment

Abstract

Selective modification of the morphology and intrinsic electrocatalytic activity of porous electrodes is urgently required to improve the performance of vanadium redox flow batteries (VRFBs). For this purpose, electrospinning was exploited to prepare high‐performance nanofiber‐based composites. Blends of polyacrylonitrile, polyacrylic acid, and polyaniline with carbon black were electrospun into a 3D free‐standing nanofibrous web, which was utilized as a novel electrode. By extending the recent theory of cyclic voltammetry at porous electrodes to account for interfacial double‐layer capacities, nonlinear effects of ohmic resistances, and parasitic reactions, we could quantitatively investigate non‐faradaic as well as desired and undesired faradaic current contributions. Combination of experimental and theoretical studies allowed a unique quantitative assessment of the intrinsic catalytic activity of selected electrode materials concerning the VO2+/VO2+ redox reaction.

Defective Carbon for Next‐Generation Stationary Energy Storage Systems: Sodium‐Ion and Vanadium Flow Batteries

“…One method explored is the incorporation of functional materials during electrospinning. [66][67][68] As an example, Maleki et al [62] reported on the incorporation of carbon black into PAN-based nanofibres, resulting in fibres with increased mean diameter and rough surface. The study revealed that the loaded mat exhibited a significantly higher specific surface area compared to commercial CF.…”

“…However, since the performance in a battery was lower than the commercial CF (energy efficiency of 68 % versus 69 % at 25 mA cm À 2 ), the study identified challenges related to mass transport limitation and inter-fibre distances, suggesting future optimisation. Optimisation performed by the same author [68] focused on the incorporation of polyaniline and carbon black into PAN and polyacrylic acid based nanofibres, aiming to enhance the electrochemical activity towards the VO 2 + /VO 2 + redox reactions. The higher presence of surface defects and amorphous carbon translated to a higher catalytic activity for the vanadium redox reactions measured by cyclic voltammetry.…”

“…Electrospinning novel carbon fibre materials could enable the creation of defects in the manufacturing process, eliminating the need for deposition of functional materials and surface treatments. One method explored is the incorporation of functional materials during electrospinning [66–68] . As an example, Maleki et al [62] .…”

Nanoparticles improving polyaniline electrical conductivity: A meta-analysis study

“…Polyaniline (PAni) is a conductive polymer from the flexible polymer family, which has high electrical conductivity (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). Among conductive polymers, PAni is unique because of its easiness of synthesis (14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25). Besides, Professor MacDiarmid et al (26) proved the PAni emeraldine base can be converted from an insulator to a metallike material by treatment with aqueous HCl, by forming the emeraldine-hydrochloride salt.…”

“…Besides, PAni has special electronic properties, which can be reversibly controlled by the material's protonation/deprotonation processes (5). In addition, PAni has great potential for highend applications, such as electrodes (18,28,38,(75)(76)(77)(78)(79)(80)(81)(82)(83), batteries (15,(84)(85)(86)(87)(88)(89)(90)(91)(92)(93), microelectronics (94)(95)(96)(97)(98)(99)(100)(101)(102), electrochromic materials used in displays (103)(104)(105)(106)(107)(108)(109)(110), sensors (22,(111)(112)(113)(114)(115)(116)(117)(118), and electromagnetic shielding (119)(12...…”