title: Balancing Osmotic Pressure of Electrolytes for Nanoporous Membrane Vanadium Redox Flow Battery with a Draw Solute.
abstract: Vanadium redox flow batteries with nanoporous membranes (VRFBNM) have been demonstrated to be good energy storage devices. Yet the capacity decay due to permeation of vanadium and water makes their commercialization very difficult. Inspired by the forward osmosis (FO) mechanism, the VRFBNM battery capacity decrease was alleviated by adding a soluble draw solute (e.g., 2-methylimidazole) into the catholyte, which can counterbalance the osmotic pressure between the positive and negative half-cell. No change of the electrolyte volume has been observed after VRFBNM being operated for 55 h, revealing that the permeation of water and vanadium ions was effectively limited. Consequently, the Coulombic efficiency (CE) of nanoporous TiO2vanadium redox flow battery (VRFB) was enhanced from 93.5% to 95.3%, meanwhile, its capacity decay was significantly suppressed from 60.7% to 27.5% upon the addition of soluble draw solute. Moreover, the energy capacity of the VRFBNM was noticeably improved from 297.0 to 406.4 mAh remarkably. These results indicate balancing the osmotic pressure via the addition of draw solute can restrict pressure-dependent vanadium permeation and it can be established as a promising method for up-scaling VRFBNM application.
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University , 5 Xinmofan Road, Nanjing 210009, P.R. China.
authors.forename: Ligen
authors.initials: L
authors.lastname: Yan
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University , 5 Xinmofan Road, Nanjing 210009, P.R. China.
authors.forename: Dan
authors.initials: D
authors.lastname: Li
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University , 5 Xinmofan Road, Nanjing 210009, P.R. China.
authors.forename: Shuaiqiang
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Chemical Engineering, University of Cincinnati , Cincinnati, Ohio 45221, United States.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Xu
authors.affiliation: Department of Chemical Engineering, University of Cincinnati , Cincinnati, Ohio 45221, United States.
authors.forename: Junhang
authors.identifier: http://orcid.org/0000-0002-4393-4968
authors.initials: J
authors.lastname: Dong
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University , 5 Xinmofan Road, Nanjing 210009, P.R. China.
authors.forename: Wenheng
authors.identifier: http://orcid.org/0000-0002-1919-9932
authors.initials: W
authors.lastname: Jing
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University , 5 Xinmofan Road, Nanjing 210009, P.R. China.
authors.forename: Weihong
authors.initials: W
authors.lastname: Xing
keywords: 2-methylimidazole; capacity decay; osmotic pressure; vanadium redox flow batteries; water transfer