Two‐Membrane Acid‐Base Flow Battery with Hydrogen Electrodes for Neutralization‐to‐Electrical Energy Conversion

Abstract

Acid‐base flow batteries (ABFB) are a promising and environmentally benign class of flow batteries that utilize neutralization energy. Among the other flow batteries, ABFBs stand out with low cost and high solubility of the electrolytes and the possibility to harvest neutralization energy of acidic and alkaline wastewaters. However, the main ABFB issues, such as low power caused by discharge current limitation and low energy density, are limiting the possibility of their implementation. In this work, a novel two‐membrane ABFB with two hydrogen electrodes was developed to overcome main ABFB issues. The proposed concept demonstrated high power density up to 6.1 mW cm−2 at 13 mA cm−2. It was shown that battery performance was greatly limited by negative electrode overvoltage. Analysis of the voltage losses allowed to estimate main power losses and highlight the possible ways to its minimization.

Mixture of Anthraquinone Sulfo-Derivatives as an Inexpensive Organic Flow Battery Negolyte: Optimization of Battery Cell

“…It can be seen that the discharge resistance of the negative electrode (ASM side) significantly exceeds that of the positive electrode (Br side) and equal 0.80 and 0.28 Ω cm 2 , respectively. Using overpotential dependencies one could separate power losses of negative electrode, positive electrode and residual constituents ( Figure 5 ), which are mainly attributed to internal resistance (see [ 51 ] for details).…”

“…In a modified cell flow field gaskets were made from Teflon TM sheets and carbon felt Sigracell GFD 4.6 (SGL Carbon, Wiesbaden, German) was used as electrodes. Membrane capillaries made of Nafion 117 stripes placed between electrode gaskets and membrane acted as reference electrodes which provide an ability to separate anodic and cathodic polarizations [ 50 , 51 ].…”

Desalination of sea water to potable levels without external energy input by electrochemical acid-base neutralisation

“…2 Flow batteries have the advantage that electrolytes containing the redox active species (i.e., energy) are stored externally to the cell and can be expanded to the desired capacity. Speci cally, relatively recent acid-base ow batteries (ABFBs), [3][4][5][6][7] which convert the Gibbs free energy of acid-base neutralisation to electricity, show promise, as they combine the bene ts of a ow battery with relatively safe and cheap electrolytes. ABFBs are a speci c case of concentration gradient batteries, in which the difference in electrochemical potential across a membrane separating two different solutions is converted into electricity (or vice versa) by coupling the process to suitable redox reactions at the negative and positive electrodes.…”

“…ABFBs are a speci c case of concentration gradient batteries, in which the difference in electrochemical potential across a membrane separating two different solutions is converted into electricity (or vice versa) by coupling the process to suitable redox reactions at the negative and positive electrodes. [3][4][5][6]8 The hydrogen evolution and oxidation reactions (HER and HOR, respectively) are ideally suited to couple trans-membrane ion transfer due to acid-base neutralisation with electron transfer across the electrode-electrolyte interface, 3,6,7 necessary for conversion of the Gibbs free energy of neutralisation to electricity.…”

“…2 We propose here a cell that combines the ABFB and ND concepts using hydrogen gas as a charge carrier for indirect neutralisation which shares some similarities with previously proposed systems. 7,12 Sáez et al 3 were the rst to show the potential of utilising hydrogen gas as a charge carrier in an ABFB with a single cation exchange membrane (CEM) separating the acid and base channel. Because the equilibrium potential of the H + /H 2 couple depends on pH, separating the acid and base in a hydrogen atmosphere generates a potential difference between the two electrodes which will result in an external current when connected.…”