不同磺化度下的磺化聚醚醚酮对全钒储能液流电池性质影响的研究

本文报道了采用浓硫酸作为磺化剂，成功合成了不同磺化度下的聚醚醚酮(PEEK)膜，并深入研究了磺化条件包括磺化时间和磺化剂的用量对所获薄膜性能的影响，获得了在不同磺化度（DS）下SPPEK膜的离子交换容，含水率，机械性能，质子电导率等参数，特别测定了在全钒液流电池工作条件下钒离子(Ⅳ)渗透率，首次为该类液流储能电池使用价廉质优的质子交换膜提供了基础实验数据。室温条件下的实验结果如下：1）磺化12小时后，膜的磺化度46%，含水量为28%，钒离子(Ⅳ)选择性最佳（钒离子渗透率为1.2×10-7 cm2/min-1，是Nafion117 (2.9×10-6 cm2/min-1)的1/24），其质子电导率只有0.02 S/cm；2）磺化96小时其磺化度达79%的膜，质子电导率达0.16 S/cm，是Nafion117 (0.10S/cm) 的1.6倍, 但其机械性能最差；3）与Nafion117膜相比，磺化在36到48小时的SPPEK膜其机械力学性能好，薄膜的钒离子渗透率、离子交换容IEC、质子导电率和含水率高，且对钒离子的选择性佳，尤其价格仅为Nafion膜的1/13，是理想的Nafion膜的代替物，可望直接应用于全钒氧化还原液流（VRB）电池中。本文还讨论了磺化时间和不同磺化剂量对膜的性质的影响。

Effect of Sulfonated Poly(ether ether ketone) Membranes with Different Sulfonation Degrees on the Performance of Vanadium Redox Flow Battery

Sulfonated poly(ether ether ketone) (SPEEK) materials were prepared by sulfonation of poly(ether ether ketone) (PEEK) in the concentrated H_2SO_4 (ca. 98%) under different time, and the SPEEK membranes were cast by a casting method and characterized by many methods. These key parameters were firstly obtained and reported, such as the ion exchange capacity (IEC), water uptake, mechanical property, proton conductivity of the membranes and vanadium(IV) ion permeability in SPEEK membranes with different degrees of sulfonation (DS). The following results were observed: (1) the membrane prepared by sulfonation for 12 h with DS of 46% had water uptake of 28%, and the vanadium(IV) ion permeability with the lowest proton conductivity of 0.02 S·cm~(-1) in SPEEK had 1.2 ×10~(-7) cm~2·min~(-1), which was 1/24 of that in Nafion 117; (2) the membrane prepared by sulfonation for 96 h with DS of 79% had the proton conductivity of 0.16 S·cm~(-1) which was 1.6 times higher than it in Nafion 117, but had the worst mechanical property; (3) the membranes with sulfonation for 36～48 h, compared with Nafion 117, not only had good integration properties such as good property of mechanics, high IEC, proton conductivity, water uptake and better selectivity to V(IV) ion, but also had very low price, which was 1/13 of that of the Nafion 117. Based upon above properties, the SPEEK membranes prepared by appropriate time are more likely to be one of the substitutes of Nafion 117 for vanadium redox flow battery (VRF) system. The effects of the degree of sulfonation of PEEK polymer and the amount of H_2SO_4 were also discussed.