Theoretical Investigation into Suitable Pore Sizes of Membranes for Vanadium Redox Flow Batteries

Abstract

For the first time, a three‐dimensional (3D) volume calculation model based on total electrostatic potential analysis and density functional calculations is applied to study the volume differences between hydrated multivalent vanadium ions (V2+, V3+, VO2+, and VO2+ ) and charge‐balancing ions (H3O+, SO42- and HSO4- ) encountered in the electrolyte solutions of vanadium redox flow batteries (VRBs). The calculated results indicate that radii of all charge‐balancing ions are less than 3.01 Å and of all hydrated multivalent vanadium ions are greater than 3.78 Å. The results of our calculations also suggest that cation‐exchange membranes with pore sizes ranging from 3.98 to 7.56 Å and anion‐exchange membranes with pore sizes ranging from 6.02 to 7.56 Å are suitable for the VRB application. These computational results agree very well with reported experimental results and provide valuable guidance for the selection and design of membranes on the molecular level for VRB applications.

Investigation of Nafion series membranes on the performance of iron‐chromium redox flow battery

“…Table 2 reports the proton conductivity result (at 25°C and 65°C) and stack resistance, respectively. 39 This mechanism is also not conducive to the diffusion of Fe 3+ as the cation. Therefore, all series of Nafion membranes demonstrate almost identical proton conductivity value, which is about 0.1 S cm −1 .…”

A Proton‐Barrier Separator Induced via Hofmeister Effect for High‐Performance Electrolytic MnO2–Zn Batteries

“…More importantly, PVA‐2H 2 O‐1HOAc‐1ZnSO 4 shows the most negative Δ E , indicating that the co‐function of OAc − and SO 4 2− can help enhance the bonding interactions to form a stable structure. [ 23 ] To get a vivid observation of the interaction regions, interaction region indicator (IRI) [ 24 ] map of PVA‐2H 2 O‐1HOAc‐1ZnSO 4 was carried out as shown in Figure 5b. Strong H‐bonds marked as HB‐HOAc, HB1, and HB2 could be seen, indicating that the enhanced H‐bonds are the mainly promoted interactions.…”

Branched Sulfonated Polyimide/Sulfonated Methylcellulose Composite Membranes with Remarkable Proton Conductivity and Selectivity for Vanadium Redox Flow Batteries

“…Vanadium redox flow battery (VRFB) with excellent system scalability, long life time, operational flexibility and eco‐friendly is a novel energy storage/conversion system . As one of the key components of VRFB, the proton conductive membrane (PCM) is used to separate the positive (VO 2+ /VO 2 + ) and negative (V 3+ /V 2+ ) electrolytes to prevent cross‐mixing of vanadium ions and allow the transport of protons (H + ) to complete the circuit . Therefore, a PCM with low vanadium ion permeability, excellent chemical stability, high proton conductivity and low cost is urgently required for VRFB application .…”