Hydration structures of vanadium/oxovanadium cations in the presence of sulfuric acid: A molecular dynamics simulation study. (23rd February 2019)

• Record Type: Journal Article
• Authors: Zhang, Ning; Yang, Boyun; Huo, Jun; Qi, Wenxu; Zhang, Xiaopeng; Ruan, Xuehua; Bao, Junjiang; He, Gaohong
• Is Part Of: Chemical engineering science. Volume 195(2019)
• Page Start: 683
• Page End: 692
• Publication Date: 2019-02-23
• Subjects: Vanadium cation -- Hydration size -- Sulfonate acid -- Proton -- Molecular dynamics simulation; Chemical engineering -- Periodicals; Génie chimique -- Périodiques; Chemical engineering; Periodicals; Electronic journals; 660
• DOI: 10.1016/j.ces.2018.10.014
• Languages: English
• ISSNs: 0009-2509

Abstract

Graphical abstract: Highlights: We estimated the hydration sizes of V 2+, V 3+, VO 2+, and VO2 + . We investigated the effects of SO4 2− and proton on the hydration structures of the vanadium cations. Proton produces competitive attraction with the vanadium cations to SO4 2− . The VRFB membrane should be fabricated with the pore size in the range of 4.12–8.14 Å. Abstract: Structure design of proton exchange membrane determines the performance of vanadium redox flow battery. Appropriate pore size of the membrane not only benefits the proton conduction but also blocks the cross contamination of the vanadium cations. For this purpose, hydration sizes of proton, vanadium(II) [V 2+ ], vanadium(III) [V 3+ ], oxovanadium(IV) [VO 2+ ], and dioxovanadium(V) [VO2 + ] cations were estimated by molecular dynamics simulation based on all-atom force field. The local hydration structures of the vanadium cations were consistent with the previous reports, verifying the adopted force field. V 2+, V 3+, VO 2+, VO2 +, and proton exhibit the hydration sizes of 8.24, 8.14, 8.18, 8.34, and 4.12 Å in the aqueous mixtures of sulfuric acid and vanadium sulfate. Thus the pore size distribution from 4.12 to 8.14 Å was recommended for the membrane fabrication. SO4 2− prefers to distribute around the vanadium cations due to electrostatic interaction, thus weakening the hydration structures of the vanadium cations. Introducing sulfuric acid decreases the local distributions of SO4 2− around V 2+ and V 3+, but increases the local distributions of SO4 2− around VO 2+ and VO2 + . This work helps to understand the structure of the aqueous mixtures of sulfuric acid and vanadium sulfate. It also provides potential guidance for improving the membrane performance in vanadium redox flow battery.