TY - JOUR
T1 - Stable and Highly Conductive Polycation-Polybenzimidazole Membrane Blends for Intermediate Temperature Polymer Electrolyte Membrane Fuel Cells
AU - Venugopalan, Gokul
AU - Chang, Kevin
AU - Nijoka, Justin
AU - Livingston, Sarah
AU - Geise, Geoffrey M.
AU - Arges, Christopher G.
N1 - Funding Information:
PI Arges acknowledges financial support for this work from LSU Lift 2 , Louisiana Board of Regents (Proof-of-Concept/Prototype Initiative), 3M Non-Tenured Faculty Award, and start-up funds provided by the Cain Department of Chemical Engineering at LSU. He also wishes to thank Dorin Boldor and Kerry Dooley for the use of their INSITRON and TGA instruments, respectively and Shri Sankar Subramanian and Vijay Ramani at Washington University St. Louis for assisting in the high temperature tensile test (ONR DURIP supported the acquisition of equipment for the high temperature tensile test). The LSU Shared Instrumentation Facilities and NMR spectrometers in the Department of Chemistry contributed to this work. We thank Dongmei Cao for assisting in the EDX mapping experiment using the SEM. Sarah Livingston’s contribution to this project was supported by a NSF REU (Award # 1560305). Geoffrey Geise acknowledges partial support for this work from the National Science Foundation under Grant No. CBET-1752048. Kevin Chang acknowledges support from the Volkswagen Group of North America Fellowship.
Publisher Copyright:
© 2019 American Chemical Society.
PY - 2020/1/27
Y1 - 2020/1/27
N2 - Intermediate-temperature polymer electrolyte membrane fuel cells (IT-PEMFCs), operating with phosphoric acid (H3PO4) doped polybenzimidazole (PBI), are severely limited by H3PO4 evaporation at high temperatures and poor resiliency in the presence of water. Polycations (PCs), on the other hand, provide good acid retention due to strong ion-pair interactions but have low conductivity due to lower ion-exchange capacity when compared to PBI. In this work, a class of H3PO4 doped PC-PBI membrane blends was prepared, and the optimal blend (50:50 ratio) exhibited remarkably high in-plane proton conductivity, near 0.3 S cm-1 at 240 °C, while also displaying excellent thermal stability and resiliency to water vapor. Microwave dielectric spectroscopy demonstrated that incorporating PBI into the PCs raised the dielectric constant by 50-70% when compared to the PC by itself. This observation explains, in part, the high proton conductivity of the optimal membrane blend. Finally, an all-polymeric membrane electrode assembly with the new materials gave a competitive IT-PEMFC performance of 680 mW cm-2 at 220 °C under dry H2/O2. Importantly, the cell was stable for up to 30 h at 220 °C and over 84 h at 180 °C. The IT-PEMFC had reasonable performance (450 mW cm-2) with 25% carbon monoxide in the hydrogen fuel.
AB - Intermediate-temperature polymer electrolyte membrane fuel cells (IT-PEMFCs), operating with phosphoric acid (H3PO4) doped polybenzimidazole (PBI), are severely limited by H3PO4 evaporation at high temperatures and poor resiliency in the presence of water. Polycations (PCs), on the other hand, provide good acid retention due to strong ion-pair interactions but have low conductivity due to lower ion-exchange capacity when compared to PBI. In this work, a class of H3PO4 doped PC-PBI membrane blends was prepared, and the optimal blend (50:50 ratio) exhibited remarkably high in-plane proton conductivity, near 0.3 S cm-1 at 240 °C, while also displaying excellent thermal stability and resiliency to water vapor. Microwave dielectric spectroscopy demonstrated that incorporating PBI into the PCs raised the dielectric constant by 50-70% when compared to the PC by itself. This observation explains, in part, the high proton conductivity of the optimal membrane blend. Finally, an all-polymeric membrane electrode assembly with the new materials gave a competitive IT-PEMFC performance of 680 mW cm-2 at 220 °C under dry H2/O2. Importantly, the cell was stable for up to 30 h at 220 °C and over 84 h at 180 °C. The IT-PEMFC had reasonable performance (450 mW cm-2) with 25% carbon monoxide in the hydrogen fuel.
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U2 - 10.1021/acsaem.9b01802
DO - 10.1021/acsaem.9b01802
M3 - Article
AN - SCOPUS:85077121729
SN - 2574-0962
VL - 3
SP - 573
EP - 585
JO - ACS Applied Energy Materials
JF - ACS Applied Energy Materials
IS - 1
ER -