Highly proton conductive, dense polybenzimidazole membranes with low permeability to vanadium and enhanced H2SO4 absorption capability for use in vanadium redox flow batteries. Issue 37 (8th September 2016)

• Record Type: Journal Article
• Authors: Jang, Jung-Kyu; Kim, Tae-Ho; Yoon, Sang Jun; Lee, Jang Yong; Lee, Jong-Chan; Hong, Young Taik
• Is Part Of: Journal of materials chemistry. Volume 4:Issue 37(2016)
• Page Start: 14342
• Page End: 14355
• Publication Date: 2016-09-08
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c6ta05080h
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : The dense BI p PBI membrane with enhanced H2 SO4 absorption capability shows higher efficiency than the Nafion 115 membrane, as well as stable cycling performance for vanadium redox flow batteries. Abstract : H2 SO4 -doped dense polybenzimidazole (PBI) membranes based on poly[2, 2′-(2-benzimidazole- p -phenylene)-5, 5′-bibenzimidazole] (BI p PBI) containing benzimidazole side groups were developed for use in vanadium redox flow batteries (VRFBs). BI p PBI was prepared by the polycondensation of 3, 3′-diaminobenzidine with 2-benzimidazole terephthalic acid (BITA) in polyphosphoric acid. Many basic properties of BI p PBI were characterized and compared with conventional PBI ( m PBI). The BI p PBI membrane has an entirely amorphous structure because of the presence of additional benzimidazole side groups, and the absorption of both H2 SO4 (65 wt%) and water (46 wt%) was significantly improved compared to the m PBI membrane in a 4 M H2 SO4 solution. The H2 SO4 -doped BI p PBI membrane has a low area resistance of 0.17 Ω cm 2 and significantly lowered permeability to vanadium ions (3.45 × 10 −8 cm 2 min −1 ). Finally, the VRFB assembled with BI p PBI had higher coulomb efficiencies (>99%) and energy efficiencies (78–95%) than Nafion 115 under a wide range of current densities (20–100 mA cm −2 ). More importantly, the VRFB with BI p PBI exhibited stable cycling performance, running for 200 charge–discharge cycles with 4.0% energy efficiency decay and 81.5% capacity retention. Furthermore, the BI p PBI membrane was stable in a highly oxidizing VO2 + solution, demonstrating its outstanding physicochemical stability. All experimental results indicate that the dense BI p PBI membrane is a promising material for VRFB applications.