Electrospun Nafion/PVDF single-fiber blended membranes for regenerative H₂/Br₂ fuel cells

Journal Article · Thu Jun 29 00:00:00 EDT 2017 · Journal of Membrane Science

DOI:https://doi.org/10.1016/j.memsci.2017.06.086· OSTI ID:1538584

Woo Park, Jun ^[1]; Wycisk, Ryszard ^[1]; Lin, Guangyu ^[2]; Ying Chong, Pau ^[2]; Powers, Devon ^[1]; Van Nguyen, Trung ^[3]; Dowd Jr., Regis P. ^[3]; Pintauro, Peter N. ^[1]

---

1. Vanderbilt University, Nashville, TN (United States)
2. TVN Systems, Inc., Lawrence, KS (United States)
3. University of Kansas, Lawrence, KS (United States)

Nafion® perfluorosulfonic acid (PFSA) and poly(vinylidene fluoride) (PVDF) were electrospun simultaneously as a polymer solution mixture using a single needle spinneret. The nanofiber morphology was highly unusual, with bundled 2–5 nm fibril strands of Nafion and PVDF aligned along the fiber axis. Membranes were made from fiber mats by a simple hot-pressing step, followed by thermal annealing, where the fibril morphology of Nafion and PVDF in the original nanofibers was retained in the membrane. The PVDF component in the final membrane served three roles, as an electrospinning carrier polymer for PFSA, a mechanical reinforcement, and a hydrophobic (uncharged) component to limit PFSA ionomer swelling. A series of single-fiber membranes with Nafion/PVDF contents ranging from 40/60 to 90/10 wt%/wt% were prepared, characterized, and evaluated for use in a regenerative hydrogen/bromine fuel cell. As anticipated, there was a decrease in proton conductivity, water/electrolyte swelling, and Br₂/Br₃^- permeability with increasing PVDF content. Membrane conductivity was lower than expected based on the weight fraction of PVDF, due presumably to an unusually large fraction of highly structured water. Nevertheless, a single-fiber Nafion/PVDF membrane with a thickness of 18 µm and an 80/20 wt%/wt% Nafion/PVDF composition performed well in a H₂/Br₂ regenerative fuel cell due to a combination of low area-specific resistance and low Br₂/Br₃- crossover. Thus, with an electrolyte containing 0.9 M Br₂ in 1.0 M HBr, the maximum power output was 46% higher than that with a Nafion 212 membrane (1.31 vs. 0.90 W/cm²).

• Research Organization: TVN Systems, Inc., Lawrence, KS (United States); Vanderbilt Univ., Nashville, TN (United States)
• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E); National Science Foundation (NSF)
• Grant/Contract Number: AR0000262; AC02-05CH11231; EFRI-1038234
• OSTI ID: 1538584
• Alternate ID(s): OSTI ID: 1550381
• Journal Information: Journal of Membrane Science, Vol. 541, Issue C; ISSN 0376-7388
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
proton exchange membrane
electrospinning
regenerative hydrogen bromine fuel cell
redox flow battery
nanofiber
nafion/PVDF blends