燃料电池用质子交换膜的结构与性能研究

Structure and properties of proton exchange membrane for fuel cells

以聚砜为前驱体、氯磺酸和8-羟基-1,3,6-芘三磺酸三钠为小分子试剂,基于后磺化方法分别制备了主链型膜材MPS-SA和侧链型膜材SPS-SA,通过FT-IR表征了其化学结构,并制备了相应的聚砜阳离子交换膜,比较了2种阳离子交换膜的性能差异。结果表明,MPS-SA和SPS-SA阳离子交换膜均表现出优异的吸水率、尺寸稳定性和质子传导性能。在相同的离子交换膜容量(IEC)下,MPS-SA由于亲水位点数多,吸水性能更优越。相反,SPS-SA阳离子交换膜由于具备长的柔性侧链,侧链末端磺酸基团的活动能力更强,使得SPS-SA显现出更好的尺寸稳定性、质子传导率和阻醇能力,其中SPS-SA-2在25℃和85℃的吸水溶胀率仅为24.4%和40.2%,相应地质子传导率达到了0.089 S/cm和0.139 S/cm,甲醇渗透率仅为7.21×10^(-7)cm^(2)/s。

Bisphenol A type polysulfone(PSF)is selected as the precursor,main chain type cation exchange membrane materials MPS-SA and side chain type cation exchange membrane materials SPS-SA are prepared via post sulfonation method by using chlorosulfonic acid and trisodium 8-hydroxy-1,3,6-pyrene trisulfonate as small molecule reagents,respectively.Chemical structures of MPS-SA and SPS-SA are confirmed by Fourier transform infrared spectroscopy(FT-IR).The corresponding sulfonated polysulfone cation exchange membranes are prepared.The performances of MPS-SA and SPS-SA cation exchange membranes are compared.It is shown that both MPS-SA and SPS-SA cation exchange membranes exhibit excellent water absorption,dimensional stability and proton conductivity.Under the same ion exchange capacity(IEC),MPS-SA cation exchange membrane shows better water absorption performance because it has more hydrophilic water points than SPS-SA.On the contrary,SPS-SA cation exchange membrane has stronger activity in its sulfonic acid groups at the end of side chain due to its longer flexible side chain,therefore,it shows better dimensional stability,proton conductivity and methanol resistance performance.The swelling ratios of SPS-SA-2 cation exchange membrane at 25℃and 85℃are only 24.4%and 40.2%,respectively.Accordingly,the proton conductivity of SPS-SA-2 cation exchange membrane reaches 0.089 S·cm^(-1)and 0.139 S·cm^(-1),respectively while the methanol permeability of SPS-SA-2 cation exchange membrane at room temperature is only 7.21×10^(-7)cm^(2)·s^(-1).