TY - JOUR
T1 - Highly Anion Conductive Polymers
T2 - How Do Hexafluoroisopropylidene Groups Affect Membrane Properties and Alkaline Fuel Cell Performance?
AU - Kimura, Taro
AU - Matsumoto, Akinobu
AU - Inukai, Junji
AU - Miyatake, Kenji
N1 - Funding Information:
This work was partly supported by the New Energy and Industrial Technology Development Organization (NEDO) of Japan through the fund for “Advanced Research Program for Energy and Environmental Technologies”, by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) Japan through Grant-in-Aids for Scientific Research (18H02030, 18H05515, 18K19111), and by Japan Science and Technology (JST) through SICORP. The authors thank Tosoh Finechem Co. for supplying 1,6-diiodododecafluorohexane.
Publisher Copyright:
© 2019 American Chemical Society.
PY - 2020/1/27
Y1 - 2020/1/27
N2 - Novel anion conductive aromatic copolymers containing hexafluoroisopropylidene groups as the hydrophobic component and fluorenyl groups substituted with pendant hexyltrimethylammonium groups as the hydrophilic component were synthesized and characterized. Precursor copolymers, BAF-AF, were synthesized by a nickel(0) promoted polycondensation reaction and had a high molecular weight (Mn = 10-12 kDa, Mw = 77-115 kDa). Quaternization of BAF-AF using dimethyl sulfate gave tough and bendable thin BAF-QAF membranes having the ion exchange capacity (IEC) from 1.3 to 2.4 mequiv g-1 by solution casting. The morphology of BAF-QAFs was investigated by TEM images and SAXS profiles, and a nanoscale fine phase-separated structure was confirmed. The BAF-QAF membrane with IEC of 2.4 mequiv g-1 showed a superior OH- conductivity (134 mS cm-1 at 80 °C) in water. The membranes retained high conductivity under strongly alkaline conditions (∼4 M KOH at 80 °C) for 1000 h. An H2/O2 anion alkaline fuel cell using the BAF-QAF membrane and binder achieved the maximum power density of 319 mW cm-2 at 702 mA cm-2 at 60 °C and 100% RH. Hexafluoroisopropylidene groups contributed to improving membrane properties as anion exchange membranes for alkaline fuel cells.
AB - Novel anion conductive aromatic copolymers containing hexafluoroisopropylidene groups as the hydrophobic component and fluorenyl groups substituted with pendant hexyltrimethylammonium groups as the hydrophilic component were synthesized and characterized. Precursor copolymers, BAF-AF, were synthesized by a nickel(0) promoted polycondensation reaction and had a high molecular weight (Mn = 10-12 kDa, Mw = 77-115 kDa). Quaternization of BAF-AF using dimethyl sulfate gave tough and bendable thin BAF-QAF membranes having the ion exchange capacity (IEC) from 1.3 to 2.4 mequiv g-1 by solution casting. The morphology of BAF-QAFs was investigated by TEM images and SAXS profiles, and a nanoscale fine phase-separated structure was confirmed. The BAF-QAF membrane with IEC of 2.4 mequiv g-1 showed a superior OH- conductivity (134 mS cm-1 at 80 °C) in water. The membranes retained high conductivity under strongly alkaline conditions (∼4 M KOH at 80 °C) for 1000 h. An H2/O2 anion alkaline fuel cell using the BAF-QAF membrane and binder achieved the maximum power density of 319 mW cm-2 at 702 mA cm-2 at 60 °C and 100% RH. Hexafluoroisopropylidene groups contributed to improving membrane properties as anion exchange membranes for alkaline fuel cells.
KW - alkaline fuel cells
KW - anion exchange membranes
KW - hexafluoroisopropylidene groups
KW - ionomers
KW - stability
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U2 - 10.1021/acsaem.9b01733
DO - 10.1021/acsaem.9b01733
M3 - Article
AN - SCOPUS:85076971267
SN - 2574-0962
VL - 3
SP - 469
EP - 477
JO - ACS Applied Energy Materials
JF - ACS Applied Energy Materials
IS - 1
ER -