ma202694p_si_001.pdf (325.58 kB)
Cross-Linked Benzoxazine–Benzimidazole Copolymer Electrolyte Membranes for Fuel Cells at Elevated Temperature
journal contribution
posted on 2016-02-22, 06:24 authored by Sung-Kon Kim, Seong-Woo Choi, Woo Seong Jeon, Jung Ock Park, Taeyun Ko, Hyuk Chang, Jong-Chan LeeHere we report new H3PO4-doped
cross-linked
benzoxazine–benzimidazole copolymer membranes showing high
proton conductivity and long-term durability for use in proton-exchange
membrane fuel cells at elevated temperatures (>100 °C). The
cross-linked
copolymer membranes were prepared by mixing of poly[2,2′-(m-phenylene)-5,5′-bibenzimidazole] (PBI) with 3-phenyl-3,4-dihydro-6-tert-butyl-2H-1,3-benzoxazine (pBUa) in N,N-dimethylacetamide,
with subsequent stepwise heating to 220 °C, and even large-sized
films (30 cm × 140 m) could be easily prepared. The membranes
showed high proton conductivities of up to 0.12 S cm–1 at 150 °C under anhydrous conditions. Membrane–electrode
assemblies (MEAs) employing the membranes showed operating voltages
of 0.71 V at 0.2 A cm–2. Furthermore, the MEAs displayed
long-term durability up to 1999 cycles, with much slower performance
decay, −0.03 mV h–1, than those prepared
using the PBI membrane in in situ accelerated lifetime
mode (load cycling testing).