BiVO₄-Decorated Graphite Felt as Highly Efficient Negative Electrode for All-Vanadium Redox Flow Batteries

Abstract

Recently, discovering high-performance electrocatalytic materials for vanadium redox flow batteries (VRFBs) has been one of the most crucial tasks. This paper details the successful fabrication of a low-cost platelike bismuth vanadate (BiVO 4 ) material through a simple one-step hydrothermal route, employed as an electrocatalyst to adorn graphite felt (GF) for use as the negative electrode in VRFBs. The experimental results show that BiVO 4 -3h exhibits the optimal electrocatalytic activity and reversibility for the vanadium redox couples among all samples. The energy efficiency of the VRFB cell assembled with BiVO 4decorated GF as the negative electrode is found to be 75.42% at 100 mA cm −2 , which is about 10.24% more efficient than that of the cell assembled with a heat-treated graphite felt (HT-GF) electrode. The possible reasons for the activity enhancement can be ascribed to the existence of oxygen vacancies in the BiVO 4 lattice structure and the relatively high surface area of BiVO 4 , which provide more active sites for facilitating the vanadium redox reactions. Furthermore, the BiVO 4 -GF electrode obstructs the competitive irreversible hydrogen evolution reaction on the negative side of the cell, and it also has better wettability. Impressively, BiVO 4 -GF as the negative electrode shows good stability over 100 cycles.

Recent advances and perspectives of practical modifications of vanadium redox flow battery electrodes

“…9a) as a negative electrode for VRFBs. 111 The electrocatalytic reaction mechanism of BiVO 4 -GF on V 2+ /V 3+ redox coupling was elucidated. The experimental results showed that BiVO 4 -3 h exhibited the best electrocatalytic activity and reversibility of vanadium redox pairs in all samples.…”

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

“…In additive processes, new materials are applied to the fibre surface. These materials can be heteroatoms (metals or nonmetals), [38,[54][55][56] graphene, [57,58] carbon dots, [59] carbon nanosphere, [60,61] carbon nanotubes (CNT), [50,62,63] reduced graphene oxide, [63,64] or other carbon. [51,65] The surface area and defect concentration play a significant role in the final performance of the electrode.…”

“…[6,143,144] However, the reaction kinetics of these materials are often poor and therefore require further treatment to enhance the electrode surface to better facilitate the vanadium reactions. Common treatment methods include thermal,, [145][146][147] chemical, [46,[148][149][150][151] electrochemical oxidation, [32,152] etching, [153] the deposition of metals [154] and metal oxides, [56,155] and the use of nanomaterials such as CNTs. [57,59,156] These methods aim to modify the chemical composition, surface structure, electrochemically active surface area, conductivity, wettability, or a combination of these characteristics.…”