燃料电池-韩子龙

1、New sulfonated polybenzimidazole (SPBI) copolymer-based proton-exchange membranes for fuel cells 韩子龙韩子龙 12121395 A B S T R A C T The synthesis and characterization of sulfonated polybenzimidazole (SPBI) copolymers as proton exchange membranes (PEMs) for fuel cells are described in this paper. The pu

2、re SPBI copolymer membrane was prepared by the traditional solutioncasting technique (technique 1), and the SPBI/H3PO4 blend membrane was prepared through a new direct hot-casting and in situ phase inversion technique (technique 2). 本文讲述了本文讲述了SPBISPBI聚合物膜的合成与特点。纯净的聚合物膜的合成与特点。纯净的SPBISPBI聚聚 合物膜是通过溶液浇注

3、技术（技术合物膜是通过溶液浇注技术（技术1 1）制备，）制备，SPBI/H3PO4 SPBI/H3PO4 共混共混 膜是由技术膜是由技术2 2制备。制备。 The membranes prepared from both techniques possessed desirable mechanical, chemical, thermal, and hydrolytic stability. However, the pure SPBI copolymer membranes from technique 1 exhibited very poor proton conductivities

4、 .On the other hand, the SPBI/H3PO4 blend membrane from technique 2 showed extremely high conductivities (0.1 S/cm) at high temperatures (120 8C) and low relative humidities (RHs) (even at anhydrous conditions), which has great potential to be used as high temperature and low humidity PEMs for fuel

5、cells. 两种技术制备的膜都呈现出了理想的机械、化学、热力和两种技术制备的膜都呈现出了理想的机械、化学、热力和 水解稳定性。然而，由技术水解稳定性。然而，由技术1 1制备的纯净的制备的纯净的SPBISPBI聚合物膜呈现聚合物膜呈现 出了非常差的质子传导率，而由技术出了非常差的质子传导率，而由技术2 2制备的制备的SPBI/H3PO4SPBI/H3PO4共混共混 膜表现出了在高温和低相对湿度下极高的传导率，有潜力应膜表现出了在高温和低相对湿度下极高的传导率，有潜力应 用于高温低相对湿度质子交换膜燃料电池。用于高温低相对湿度质子交换膜燃料电池。 Membrane preparation The

6、 pure SPBI copolymer membranes were prepared by the traditional solution-casting technique (technique 1). The SPBI copolymer (in potassium salt form) was dissolved in DMSO to obtain a homogeneous solution with the concentration of 5 wt.%. The membranes with a controlled thickness were prepared by ca

7、sting the solutions onto clean glass plates.The as-cast films were dried in a hood overnight, followed by drying in an oven at 80 8C for 6 h and 120 8C for 12 h. Then, the membranes were carefully removed from the glass substrates, and were soaked for the purpose of protonexchange treatment in 1.0M

8、hydrochloric acid at room temperature for more than 24 h. 溶液浇注技术（技术溶液浇注技术（技术1 1）：）：SPBISPBI聚合物溶解在二甲基亚砜聚合物溶解在二甲基亚砜 以获得质量比为以获得质量比为5%5%的均匀溶液，通过把溶液浇注到干净的玻的均匀溶液，通过把溶液浇注到干净的玻 璃器皿可以得到可控厚度的膜。铸态的薄膜在罩中烘干一整璃器皿可以得到可控厚度的膜。铸态的薄膜在罩中烘干一整 夜，接着分别在夜，接着分别在8080度烤箱烘干度烤箱烘干6 6小时和在小时和在120120度烤箱烘干度烤箱烘干1212小小 时。然后，膜从地板成功取出，在室

9、温下浸泡在时。然后，膜从地板成功取出，在室温下浸泡在1.0M1.0M的盐酸的盐酸 溶液溶液2424小时以上，以便获取质子交换膜。小时以上，以便获取质子交换膜。 The resulting free-standing membranes (in acid form) were thoroughly washed with de-ionized water and dried in vacuum at 90 8C overnight (Fig. 2(a). A Mitutoyo Electronic Indicator (Model: 543-252B, Mitutoyo America Corp

10、oration, Aurora, IL) was used to measure the membrane thickness with an accuracy of 0.5 mm. The final membranes had a thickness of approximately 30 mm. 由此产生的自力式膜被彻底清洗，在由此产生的自力式膜被彻底清洗，在9090度真空干燥一整夜。度真空干燥一整夜。 一个三丰公司电子指示器被用于测量膜的厚度，其精度为一个三丰公司电子指示器被用于测量膜的厚度，其精度为 0.5mm 0.5mm。最终膜的厚度恰好是。最终膜的厚度恰好是30mm30mm。 T

11、he SPBI-1/H3PO4 blend membrane was prepared through a new direct hot-casting and in situ phase inversion technique (technique 2) (Xiao et al., 2005). After polymerization, the hot viscous solution with a concentration of 7.87 wt.% was cast directly on a glass plate in an oven at 180 8C with a contro

12、lled thickness. Then, the wet membrane was cooled from the polymerization temperature to room temperature in a hood (25 8C and 45% RH) for 24 h. 掺入磷酸的膜是通过一种新的方式制备。聚合以后，质量分掺入磷酸的膜是通过一种新的方式制备。聚合以后，质量分 数数 为为7.87%7.87%的均匀热粘性溶液被直接放入的均匀热粘性溶液被直接放入180180度烤箱中的玻璃器皿中，度烤箱中的玻璃器皿中， 然后，湿膜冷却然后，湿膜冷却2424小时，从聚合温度降到室温。小

13、时，从聚合温度降到室温。 In this period, in situ phase inversion (transition from the solution state to the gel state) of the membrane was observed during the hydrolysis of the solvent PPA (a good solvent for SPBI-1) to PA (a poor solvent for SPBI-1) since both SPBI-1 and PPA are extremely hygroscopic and the m

14、oisture could be easily absorbed to hydrolyze PPA into PA. Finally, a very uniform and flexible SPBI-1/H3PO4 blendmembrane was obtained (Fig. 2(b). The membrane was wiped with a tissue paper to remove all remaining H3PO4 on the membrane surface and was dried in an oven at 120 8C for 10 h. The final

15、membrane had a thickness of about 70 mm. 最后非常均匀灵活的最后非常均匀灵活的SPBI-1/H3PO4共混膜被获取，新的膜共混膜被获取，新的膜 能很好的吸湿。在能很好的吸湿。在120度烤箱烘干度烤箱烘干10小时以后，用纸巾擦拭小时以后，用纸巾擦拭 纸去除膜表面所有剩余的纸去除膜表面所有剩余的H3PO4，最终膜的厚度约，最终膜的厚度约70毫米。毫米。 Membrane characterization The pure SPBI copolymer membranes (from technique 1) and the SPBI-1/H3PO4 blen

16、d membrane (from technique 2) were characterized with ion-exchange capacity (IEC), Fourier transform infrared (FTIR) spectrometry, thermogravimetric analysis (TGA), H3PO4-doping level, and proton conductivity measurements 离子交换能力、傅里叶变换红外光谱、热重分析、离子交换能力、傅里叶变换红外光谱、热重分析、 掺混磷酸后的水平、离子电导率测量掺混磷酸后的水平、离子电导率测量

17、1. Ion-exchange capacity The IEC was measured by means of a classical titration method. A membrane sample of about 0.200 g was soaked in 50 mL of 1.0 M NaCl solution for 2 days. The released proton concentration was titrated using a 0.01-M NaOH solution IECIEC测量通过一个经典滴定法。大约测量通过一个经典滴定法。大约0.2g0.2g的膜样本

18、浸泡在的膜样本浸泡在 5050毫升的毫升的1M1M氯化钠溶液氯化钠溶液2 2天。释放离子的浓度用天。释放离子的浓度用0.01 - M0.01 - M 氢氧化钠溶液滴定。氢氧化钠溶液滴定。 2. Fourier transform infrared spectra TFTIR spectra were recorded on a Nexus 4701 FTIR Spectrometer. Each of the membrane samples was put in appropriate physical contact with the sampling plate of the spect

19、rometer accessory, yielding high quality and reproducible spectra. 3. Thermogravimetric analysis TGA was performed to estimate the thermal stability of the membranes with a Pyris 1 TGA thermogravimetric analyzer (PerkinElmer, Shelton, CT) at a heating rate of 20 8C/min in N2 in the temperature range

20、 of 30800 8C. 4. H3PO4-doping level the H3PO4-doping level could be calculated from the following equation: 5. Proton conductivity measurement The pictures of the apparatus for proton conductivity measurements: (a) outside appearance of the assembled conductivity cell and (b) inside structure of the conductivity cell. Conclusions The new sulfonated polybenzimidazole copolymers were successfully synthesized in this work. The pure SPBI copolymer membranes were prepared by the traditional solution-casting technique. However, the resulting membranes exhibited very low protonconductivities