Electrode Treatments for Redox Flow Batteries: Translating Our Understanding from Vanadium to Aqueous‐Organic

Abstract

Redox flow batteries (RFBs) are a promising technology for long‐duration energy storage; but they suffer from inefficiencies in part due to the overvoltages at the electrode surface. In this work, more than 70 electrode treatments are reviewed that are previously shown to reduce the overvoltages and improve performance for vanadium RFBs (VRFBs), the most commercialized RFB technology. However, identifying treatments that improve performance the most and whether they are industrially implementable is challenging. This study attempts to address this challenge by comparing treatments under similar operating conditions and accounting for the treatment process complexity. The different treatments are compared at laboratory and industrial scale based on criteria for VRFB performance, treatment stability, economic feasibility, and ease of industrial implementation. Thermal, plasma, electrochemical oxidation, CO2 treatments, as well as Bi, Ag, and Cu catalysts loaded on electrodes are identified as the most promising for adoption in large scale VRFBs. The similarity in electrode treatments for aqueous‐organic RFBs (AORFBs) and VRFBs is also identified. The need of standardization in RFBs testing along with fundamental studies to understand charge transfer reactions in redox active species used in RFBs moving forward is emphasized.

Reduced graphene oxide/MXene hybrid decorated graphite felt as an effective electrode for vanadium redox flow battery

“…have been reported to improve battery performance. 25–27 For example, González et al 28 prepared a graphene-graphite composite electrode using an electrophoretic deposition method. The modified graphite felt exhibited an improved electrochemical activity and kinetic reversibility for the VO 2+ /VO 2 + redox couple with a high energy efficiency of 95.80% at a current density of 25 mA cm −2 .…”