Direct borohydride fuel cell performance using hydroxide‐conducting polymeric nanocomposite electrolytes

Abstract

Solid electrolyte membranes based on alkali‐doped polyvinyl alcohol (PVA) and PVA/carbon nanotubes (PVA/CNTs) are used in direct borohydride fuel cells (DBFCs). As 0.05 wt % of CNT is incorporated into the PVA matrix, the polymer crystallinity is decreased from 42.4% to 38.0% and the fractional free volume increases from 2.48% to 3.53%. The KOH‐doped PVA/CNT exhibits the highest ionic conductivity of 0.0805 S cm−1, because of the increased polymer free volume (which promotes vehicular OH− transport) and the presence of CNT (which serves as the conducting microchannels). Sodium borohydride (NaBH4) in NaOH solution and potassium borohydride (KBH4) in KOH mixture are fed into the cells. The power density of the KBH4‐based DBFC is almost twice that of the NaBH4‐based DBFC (184 vs. 92 mW cm−2) due to less KBH4 permeability through the films, higher conductivity of the KOH‐doped PVA composites than those in the sodium counterpart, and probably higher electro‐catalytic kinetics. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1779–1789, 2013

Novel quaternized polyvinyl alcohol/quaternized chitosan nano-composite as an effective hydroxide-conducting electrolyte

“…The ions may transport through the KOH-doped PVA film via the vehicular, bulk diffusion mechanism [61]. The Q-PVA electrolyte provides additional -N + (CH 3 ) 3 functional groups as fixed sites for ions to "hop" from one group to another, and this mechanism is known as the hopping mechanism [62].…”

Novel bilayer well-aligned Nafion/graphene oxide composite membranes prepared using spin coating method for direct liquid fuel cells

“…Finally, the single cell assembly was bolted and screwed together using a torque wrench at a torque force of 392 N cm. This experimental apparatus was illustrated in our previous publications [40,42]. The liquid fuel (5 M and 8 M formic acid, 2 M methanol, or 3 M ethanol, which was found to be the optimal fuel concentration [14]) was fed into a thermostatic chamber at 80°C and recirculated through the anode compartment at a flow rate of 5 mL min À 1 .…”

“…The fuel transported through the membranes into the receiving reservoir was determined periodically by using a pH meter (model 6010 pH meter, Jenko Instruments, Inc., San Diego, CA, USA) [39] or a density/ specific gravity meter (model DA-130N, Kyoto Electronics Manufacturing Co., Ltd., Kyoto, Japan). The fuel permeability (P, in cm 2 s À 1 ) was calculated using the following equation [40]:…”

Swelling-Resistant, Crosslinked Polyvinyl Alcohol Membranes with High ZIF-8 Nanofiller Loadings as Effective Solid Electrolytes for Alkaline Fuel Cells

“…Even at a minute amount (0.05%) carbon nanotube (CNT) load, the PVA/CNT membrane exhibited an FFV of 3.53%, increased from 2.48% of pure PVA film [ 63 ]. At the same time, the polymer crystallinity dropped from 42% to 38% [ 70 ]. For crosslinked quaternized PVA/quaternized chitosan (QPVA/Qchitosan) composite at 5% load, the FFV increased from 2.0 to 3.1%, and crystallinity decreased from 9.8 to 6.4% [ 17 , 66 ].…”