Nonhumidified Intermediate Temperature Fuel Cells Using Protic Ionic Liquids
Nonhumidified Intermediate Temperature Fuel Cells Using Protic Ionic Liquids
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DOI：
10.1021/ja102367x
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发表时间：
2010-07-21
影响因子：
15
通讯作者：
Watanabe, Masayoshi
中科院分区：
文献类型：
--
作者：
Lee, Seung-Yul;Ogawa, Atsushi;Watanabe, Masayoshi
在本文中，质子离子液体，二乙基甲基铵三氟甲磺酸盐（[dema][TfO]），作为燃料电池的质子导体的表征和膜型燃料电池系统的制造使用[dema][TfO]在非增湿条件下，在中温下详细描述。在物理化学和电化学性质方面，[dema][TfO]对燃料电池电极反应表现出高活性（即，氢氧化反应（HOR）和氧还原反应（ORR）），并且液体燃料电池的开路电压（OCV）在150 ℃时为1.03V，如参考文献27中所报道的。然而，二乙基甲基铵双（三氟甲磺酰基）酰胺（[dema][NTf 2]）具有相对低的HOR和ORR活性，因此，OCV约为0.05。0.7 V，尽管[dema][NTf 2]和[dema][TfO]具有相同的阳离子（[dema]）和相似的热和体传输性质。质子传导主要通过[dema][TfO]中的载体机制发生，质子转移数（t（+））为0.5-0.6。这种相对低的t（+）对于质子导体似乎比对于其它电解质如水合磺化聚合物电解质膜（t（+）= 1.0）更不利。然而，在模型化合物中，铵阳离子和胺之间发生快速质子交换反应。这表明质子交换机制有助于燃料电池系统的运行，其中去质子化胺通过阴极反应连续产生，并且避免了电池的极化。二乙基甲基铵形式的六元磺化聚酰亚胺与[dema][TfO]具有优异的相容性。该复合膜可以获得高达80重量%的[dema][TfO]含量，并表现出良好的热稳定性，高离子电导率，和机械强度和气体渗透的水合Nafion的那些可比。使用该复合膜制备的H-2/O-2燃料电池可以在30 ~ 140 ℃的温度下在非增湿条件下成功地工作，在120 ℃下获得250 mA cm-2的电流密度。质子离子液体及其复合膜是一种可能的候选人的电解质的H-2/O-2燃料电池，在非增湿条件下运行。
In this paper, the characterization of a protic ionic liquid, diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]), as a proton conductor for a fuel cell and the fabrication of a membrane-type fuel cell system using [dema][TfO] under nonhumidified conditions at intermediate temperatures are described in detail. In terms of physicochemical and electrochemical properties, [dema][TfO] exhibits high activity for fuel cell electrode reactions (i.e., the hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR)) at a Pt electrode, and the open circuit voltage (OCV) of a liquid fuel cell is 1.03 Vat 150 degrees C C, as has reported in ref 27. However, diethylmethylammonium bis(trifluoromethane sulfonyl)amide ([dema][NTf2]) has relatively low HOR and ORR activity, and thus, the OCV is ca. 0.7 V, although [dema][NTf2] and [dema][TfO] have an identical cation ([dema]) and similar thermal and bulk-transport properties. Proton conduction occurs mainly via the vehicle mechanism in [dema][TfO] and the proton transference number (t(+)) is 0.5-0.6. This relatively low t(+) appears to be more disadvantageous for a proton conductor than for other electrolytes such as hydrated sulfonated polymer electrolyte membranes (t(+) = 1.0). However, fast proton-exchange reactions occur between ammonium cations and amines in a model compound. This indicates that the proton-exchange mechanism contributes to the fuel cell system under operation, where deprotonated amines are continuously generated by the cathodic reaction, and that polarization of the cell is avoided. Six-membered sulfonated polyimides in the diethylmethylammonium form exhibit excellent compatibility with [dema][TfO]. The composite membranes can be obtained up to a [dema][TfO] content of 80 wt % and exhibit good thermal stability, high ionic conductivity, and mechanical strength and gas permeation comparable to those of hydrated Nafion. H-2/O-2 fuel cells prepared using the composite membranes can successfully operate at temperatures from 30 to 140 degrees C under nonhumidified conditions, and a current density of 250 mA cm(-2) is achieved at 120 degrees C. The protic ionic liquid and its composite membrane are a possible candidate for an electrolyte of a H-2/O-2 fuel cell that operates under nonhumidified conditions.