长侧链季铵基团功能化聚(亚芳基-哌啶鎓盐)阴离子交换膜的制备及在全钒液流电池中的应用

Anion exchange membranes based on long side-chain quaternary ammonium-functionalized poly(arylene piperidinium)s for vanadium redox flow batteries

离子选择性是全钒氧化还原液流电池(VRFBs)用膜材料的重要性能指标.本文以主链中没有醚键的聚(亚芳基哌啶-哌啶)(PTP)为基体材料,通过其和碘甲烷、1-溴戊烷和(5-溴戊基)-三甲基溴化铵间的门秀金(Menshutkin)反应,使PTP中哌啶基团季铵化,合成了不同侧链接枝的聚(亚芳基-哌啶鎓盐)型阴离子交换膜(AEMs).研究了AEMs的硫酸掺杂含量、溶胀性、钒离子渗透性、离子选择性、面电阻、机械性能、全钒液流电池性能和循环寿命.同时提出了一种测量AEMs氢离子透过率的方法,结果表明,氢离子在AEMs中也能有效传导.长侧链季铵盐接枝的膜材料(PTP-QA)具有最高的H^(+)透过率,同时具有较低的面电阻和良好的阻钒性能.PTP-QA膜的离子选择性(电导率与钒离子透过率的比值)是Nafion 115离子选择性的370倍.由PTP-QA膜组装的VRFB,在80-160 mAcm^(-2)电流密度下的库伦效率高于99%;在100 mAcm^(-2)下的能量效率高达89.8%(Nafion 115组装的VRFB的能量效率为73.6%);同时,该VRFB也表现出良好的循环稳定性和容量保持率.研究表明聚(亚芳基-哌啶鎓盐)型AEMs在VRFB中具有潜在的应用价值.

A new series of poly(arylene piperidinium)-based anion exchange membranes(AEMs)are proposed for vanadium redox flow batteries(VRFBs).The AEMs are fabricated via the Menshutkin reaction between poly(arylene piperidine)without ether bonds in the backbone and various quaternizing agents,including iodomethane,1-bromopentane,and(5-bromopentyl)-trimethylammonium bromide.The properties of the AEMs are investigated in terms of sulfuric acid doping content,swelling,vanadium permeability,ion selectivity,area-specific resistance,mechanical properties,VRFB performance,and cyclic testing.Particularly,a method of measuring the H^(+) permeability of the AEM is developed.It demonstrates that the poly(p-terphenyl-N-methylpiperidine)-quaternary ammonium(PTP-QA)membrane with a QA cation-tethered alkyl chain exhibits high H^(+) permeability,resulting in low area resistance.Combined with its low vanadium permeance,the PTP-QA membrane achieves nearly 370 times higher ion selectivity than Nafion 115.The VRFB based on PTP-QA-based AEM displays high Coulombic efficiencies above 99% at current densities of 80-160 mA cm^(-2).The higher energy efficiency of 89.8% is achieved at 100 mA cm^(-2)(vs.73.6% for Nafion 115).Meanwhile,the PTPQA-based AEM shows good cycling stability and capacity retention,proving great potential as the ion exchange membrane for VRFB applications.