| 1. |
- Choi, Seung Young, et al.
(författare)
-
Nanostructure-property relationship of two perfluorinated sulfonic acid (PFSA) membranes
- 2022
-
Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 0363-907X .- 1099-114X. ; 46:8, s. 11265-11277
-
Tidskriftsartikel (refereegranskat)abstract
- The physicochemical properties of perfluorinated sulfonic acid (PFSA) polymers are closely correlated with their nanostructure. However, their real nano-structural morphology is still controversial because it is difficult to observe their accurate morphology at the nanoscale. Moreover, studies on the nanostructures of the PFSA membranes have been mainly focused on the ionic domain. On this basis, here we describe the crystalline domain of two PFSA membranes as well as their ionic domain based on small-angle X-ray scattering results. Both ionic and crystalline domains showed significant alterations during hydration, and the different behaviors based on the side-chain length of the two PFSA membranes are also described. The short side chain-tethered PFSA membrane (higher ion exchange capacity (IEC)) showed a widespread ionic domain and lacking crystalline domain with their relatively temperature-dependent tendency compared to the flexible long side chain-tethered PFSA membrane (lower IEC). On this basis, the correlation between nanostructure and membrane properties is described from various perspectives.
|
|
| 2. |
- Do, Xuan Huy, et al.
(författare)
-
Membrane Assemblies with Soft Protective Layers : Dense and Gel-Type Polybenzimidazole Membranes and Their Use in Vanadium Redox Flow Batteries
- 2022
-
Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 18:50
-
Tidskriftsartikel (refereegranskat)abstract
- Polybenzimidazole (PBI) membranes show excellent chemical stability and low vanadium crossover in vanadium redox flow batteries (VRFBs), but their high resistance is challenging. This work introduces a concept, membrane assemblies of a highly selective 2 µm thin PBI membrane between two 60 µm thick highly conductive PBI gel membranes, which act as soft protective layers against external mechanical forces and astray carbon fibers from the electrode. The soft layers are produced by casting phosphoric acid solutions of commercial PBI powder into membranes and exchanging the absorbed acid into sulfuric acid. A conductivity of 565 mS cm−1 is achieved. A stability test indicates that gel mPBI and dense PBI-OO have higher stability than dense mPBI and dense py-PBI, and gel/PBI-OO/gel is successfully tested for 1070 cycles (ca. 1000 h) at 100 mA cm−2 in the VRFB. The initial energy efficiency (EE) for the first 50 cycles is 90.5 ± 0.2%, and after a power outage stabilized at 86.3 ± 0.5% for the following 500 cycles. The initial EE is one of the highest published so far, and the materials cost for a membrane assembly is 12.35 U.S. dollars at a production volume of 5000 m2, which makes these membranes very attractive for commercialization.
|
|
