Development of perfluorosulfonic acid polymer‐based hybrid composite membrane with alkoxysilane functionalized polymer for vanadium redox flow battery

Abstract

Summary A new kind of alkoxy silane functionalized polymer (ASFP) is synthesized by selectively functionalized carboxyl groups as a novel inorganic precursor polymer to prepare organic‐inorganic hybrid membrane for vanadium redox flow battery (VRFB) system. The novel hybrid membrane has been fabricated by interconnection between hydrophilic domains of Nafion and ASFP functional group. The effective concentration of ASFP for hybrid membrane is 25% (wt/wt). The proton conductivity and selectivity of the hybrid membrane are comparable with those of the Nafion212 membrane, which is mainly attributed by the presence of additional hydrophilic domains in the hybrid membrane. The proton conductivity and ion exchange capacity of the Nafion‐ASFP (75:25) membrane is 0.061 S/cm and 0.68 meq/g, respectively. Remarkably, the Nafion‐ASFP membrane shows a low vanadium permeability (1.259 × 10−7 cm2/min) and high selectivity, which is an excellent advantage. As a result, the hybrid membrane shows comparable efficiency performance with Nafion212 over 50 cycles. Notably, the VRFB unit cell with Nafion‐ASFP membrane achieves higher coulombic efficiency than Nafion212. The hybrid membrane reveals a new route to develop an alternative fluorinated polymer membrane with numerous advantages especially cost‐effectiveness, homogeneous dispersion of inorganic silica precursor materials in the hybrid membrane without deterioration of mechanical strength, and lower vanadium ion crossover for VRFB system.

Surface-Modified Approach to Fabricate Nafion Membranes Covalently Bonded with Polyhedral Oligosilsesquioxane for Vanadium Redox Flow Batteries

“…19 To reduce the permeability of ions and improve the ion selectivity of Nafion membranes, several methods have been proposed, such as the incorporation of inorganic nanofillers 20−22 or by blending other polymers with Nafion. 23,24 exhibited preeminent proton conductivity and VO 2+ blockage property. 22 Sadhasivam et al blended Nafion with an alkoxy silane functionalized polymer (ASFP) to fabricate a novel membrane.…”

“…The hydrophilic domains of Nafion were connected with ASFP, resulting in a decreased VO 2+ permeability of 1.259 × 10 −7 cm 2 min −1 and a high selectivity of 0.0508 × 10 7 S s cm −3 . 24 Polyhedral oligosilsesquioxane (POSS) is a cage-like macromer with an inorganic silica-like Si 8 O 12 in the core surrounded by eight corner organic substitutes. 25 The nanosized core and eight organic substitutes endow POSS hybrid materials with good dispersion and compatibility on a nanoscale or a molecular level.…”

Ultrahigh Proton/Vanadium Selective and Durable Nafion/TiZrO4 Composite Membrane for High-Performance All-Vanadium Redox Flow Batteries

“…The VFB performance associated with the Nafion/TiZrO 4 NT-1, Nafion/TiO 2 NT-1, Nafion/ZrO 2 NT-1, and Nafion-212 membranes is investigated to compare with the recently reported Nafion composite membranes (Table ). The Nafion/TiZrO 4 NT-1 composite membrane displays the highest proton conductivity, lowest permeability of vanadium ions, and highest ion selectivity than those of Nafion-based composite membranes of rN212/T1.5, rN212/GO, Nafion-ASFP (75:25), Nafion-(SN@APTES-PWA)-4.5 wt %, BC–PFSA, Nafion-(NKFs@PWA)-30 wt %, CLGO/Nafion212, and Nafion-(NKFs@NSP/PWA)-15 wt % . Moreover, a superior VFB CE, EE, and outstanding self-discharge time were obtained for the Nafion/TiZrO 4 NT-1 composite membrane as compared to the recently reported Nafion composite membranes. − ,− …”

Thin Reinforced Ion-Exchange Membranes Containing Fluorine Moiety for All-Vanadium Redox Flow Battery

“…However, in the case of hydrocarbon-based IEMs, despite their excellent electrochemical characteristics, they are difficult to apply to practical systems due to their poor chemical stability, so research on this is urgently needed [2,10,14,15]. In addition, a partially fluorinated IEM can be considered to improve the chemical stability and reduce the manufacturing cost of the IEMs [16][17][18][19][20].…”

“…stability, so research on this is urgently needed [2,10,14,15]. In addition, a partially fluorinated IEM can be considered to improve the chemical stability and reduce the manufacturing cost of the IEMs [16][17][18][19][20]. The traditional manufacturing process (i.e., "a paste method") of commercial IEMs is known to be complicated and expensive.…”