The Influence of Some Electrolyte Additives on the Electrochemical Performance of Fe/Fe2+Redox Reactions for Iron/Iron Redox Flow Batteries

For the application in Fe/Fe-Redox-Flow-Batteries some important factors concerning the composition of the electrolyte and the influence of temperature on the properties of half-cell reactions were investigated. In contrast to previous investigations, the measurements were performed more realistically on deposited iron and by means of linear sweep voltammetry. Since the distinction between cathodic iron deposition and hydrogen generation is not possible by convention, with quantitative stripping analysis on a rotating disk electrode, partly a method was used to distinguish between these two reactions. The investigations were carried out at temperatures up to 80 °C, with addition of 10 mM of chlorides of Bi, Cu, In, Pb, Sn, Tl, Cd, Sb and Hg and different supporting salts of NH$_{4}$$^{+}$, Li$^{+}$, K$^{+}$. Na$^{+}$, Cs$^{+}$, Mg$^{2+}$ and Al$^{3+}$

Use of Carbon Additives towards Rechargeable Zinc Slurry Air Flow Batteries

The performance of redox flow batteries is notably influenced by the electrolyte, especially in slurry-based flow batteries, as it serves as both an ionic conductive electrolyte and a flowing electrode. In this study, carbon additives were introduced to achieve a rechargeable zinc slurry flow battery by minimizing the zinc plating on the bipolar plate that occurs during charging. When no carbon additive was present in the zinc slurry, the discharge current density was 24 mA∙cm$^{-2}$ at 0.6 V, while the use of carbon additives increased it to up to 38 mA∙cm$^{-2}$. The maximum power density was also increased from 16 mW∙cm$^{-2}$ to 23 mW∙cm$^{-2}$. Moreover, the amount of zinc plated on the bipolar plate during charging decreased with increasing carbon content in the slurry. Rheological investigation revealed that the elastic modulus and yield stress are directly proportional to the carbon content in the slurry, which is beneficial for redox flow battery applications, but comes at the expense of an increase in viscosity (two-fold increase at 100 s$^{-1}$). These results show how the use of conductive additives can enhance the energy density of slurry-based flow batteries

Aspects of electron transfer processes in vanadium redox-flow batteries

The electrochemical processes in vanadium redox-flow batteries (VRFBs) include conversions of vanadium species in acidic electrolytes with total vanadium concentrations over molar range. The majority of currently available data on electrode kinetics of vanadium reactions, and on the role of electrode surface chemistry are obtained for diluted electrolyte solutions and are very controversial. In this minireview, we consider the interpretations of electrochemical kinetic data for vanadium electrode reactions and mechanistic concepts, which have been reported in the literature. Thereby, the gap between electrochemical kinetics in “diluted” and “concentrated” solutions is in the focus of the review

Techno-economic modeling and analysis of redox flow battery systems

A techno-economic model was developed to investigate the influence of components on the system costs of redox flow batteries. Sensitivity analyses were carried out based on an example of a 10 kW/120 kWh vanadium redox flow battery system, and the costs of the individual components were analyzed. Particular consideration was given to the influence of the material costs and resistances of bipolar plates and energy storage media as well as voltages and electric currents. Based on the developed model, it was possible to formulate statements about the targeted optimization of a developed non-commercial vanadium redox flow battery system and general aspects for future developments of redox flow batteries

Use of Carbon Additives towards Rechargeable Zinc Slurry Air Flow Batteries

International audienceThe performance of redox flow batteries is notably influenced by the electrolyte, especially in slurry-based flow batteries, as it serves as both an ionic conductive electrolyte and a flowing electrode. In this study, carbon additives were introduced to achieve a rechargeable zinc slurry flow battery by minimizing the zinc plating on the bipolar plate that occurs during charging. When no carbon additive was present in the zinc slurry, the discharge current density was 24 mA•cm −2 at 0.6 V, while the use of carbon additives increased it to up to 38 mA•cm −2. The maximum power density was also increased from 16 mW•cm −2 to 23 mW•cm −2. Moreover, the amount of zinc plated on the bipolar plate during charging decreased with increasing carbon content in the slurry. Rheological investigation revealed that the elastic modulus and yield stress are directly proportional to the carbon content in the slurry, which is beneficial for redox flow battery applications, but comes at the expense of an increase in viscosity (two-fold increase at 100 s −1). These results show how the use of conductive additives can enhance the energy density of slurry-based flow batteries