全钒液流电池用磺化聚醚醚酮/锂皂石质子膜的结构及性能

通过溶液流延法制备了磺化聚醚醚酮/锂皂石(SPEEK/Lap)复合膜, 对其物理化学性质、 机械性能、 化学稳定性及单电池性能进行了测试. 在SPEEK基质中引入的Lap有效改善了复合膜的质子传导率、 溶胀率和机械性能. 当Lap添加量(质量分数)从0.2%增到1.5%时, 复合膜的质子传导率随之增加(19.9~23.6 mS/cm). SPEEK/Lap-0.2复合膜的自放电时间为57.2 h, 是Nafion 117膜的2.4倍和纯SPEEK膜的1.5倍. 在80 mA/cm ²电流密度下, SPEEK/Lap-0.2复合膜的电压效率(VE, 86.5%)和能量效率(EE, 84.0%)明显高于Nafion 117膜(VE: 83.8%, EE: 80.7%)和纯SPEEK膜(VE: 81.4%, EE: 78.9%). 同时, SPEEK/Lap-0.2复合膜经100次充放电循环测试后具有良好的循环稳定性和结构稳定性.     

自交联型磺化聚醚醚酮质子交换膜的合成

以含3,3'-二烯丙基双酚 A 结构单元的聚醚醚酮为基膜材料, 通过自由基加成反应在取代基上引入磺酸基团, 合成侧链型磺化聚醚醚酮(SPEEK)质子交换膜. 用傅里叶变换红外(FTIR)光谱、 核磁共振氢谱(¹H NMR)、 热重分析(TG)和扫描电子显微镜(SEM)等方法对 SPEEK 的结构进行表征. 实验结果表明, 巯基丙磺酸被接枝在聚醚醚酮侧基上, SPEEK 膜具有明显的亲水疏水微相分离形貌, 磺酸基团相互聚集形成离子通道. SPEEK 膜离子交换容量为 2.12 mmol/g, 钒离子渗透率为 1.54×10^-6 cm²/min, 低于Nafion117 膜的钒离子渗透率, 阻钒能力优于 Nafion117 膜. 以 SPEEK-4 膜组装电池的自放电时间约为130 h, 长于 Nafion117 膜的 66 h. 电池充放电循环 50 次, SPEEK-4 膜的库仑效率、 电压效率和能量效率没有明显降低, 显示出良好的稳定性.     

Influences of permeation of vanadium ions through PVDF-g-PSSA membranes on performances of vanadium redox flow batteries

The preparation and physical characterization of a poly(vinylidene fluoride)-graft-poly(styrene sulfonic acid) (PVDF-g-PSSA) membrane prepared by a solution-grafting method were described. These membranes exhibited high conductivity with a value 3.22 x 10(-2) S/cm at 30 degrees C. ICP studies revealed that the PVDF-g-PSSA membrane showed dramatically lower vanadium ion permeability compared to Nafion 117. Trivalent vanadium ions had the highest permeability through all these membranes in contrast to pentavalent vanadium ions with the lowest. The VRB with the low-cost PVDF-g-PSSA membrane exhibited a higher performance than that with Nafion 117 under the same operating conditions, and its energy efficiency reached 75.8% at 30 mA/cm(2). The performance of VRB with the PVDF-g-PSSA membrane can be maintained after more than 200 cycles at a current density of 60 mA/cm(2).     

质子交换膜对钒氧化还原液流电池性能的影响

采用溶液接枝聚合法制备了一种新型的质子交换膜PVDF-g-PSSA, 测定了PVDF-g-PSSA膜、Nafion 117 膜和PE01均相膜的离子交换能力和电导率, 并分别研究了以这3种膜为隔膜的钒电池的电化学性能. 实验结果表明, PVDF-g-PSSA膜具有优良的质子电导率和离子交换能力, 室温下其离子交换能力和质子电导率分别为1.13 mmol/g和3.22×10-2 S/cm, 在不同的充放电电流密度下, 以PVDF-g-PSSA膜为隔膜的钒电池的库仑效率和能量效率明显高于Nafion 117膜和PE01均相膜为隔膜的钒电池; PVDF-g-PSSA膜阻钒离子的渗透性能与PE01均相膜基本一致, 都明显优于Nafion 117膜的阻钒离子渗透能力.     

基于磷钨酸功能化纳米纤维的超高质子/钒选择性的聚苯并咪唑膜在全钒液流电池中的应用

Proton exchange membrane (PEM) is a key component of vanadium redox flow battery (VRB), and its proton/vanadium selectivity plays an important role in the performance of a VRB single cell. Commercially available perfluorosulfonic acid (Nafion) membranes have been widely used due to their excellent proton conductivity and favorable chemical resistance. However, the large pore size micelle channels formed by the pendant sulfonic acid groups lead to the excessive penetration of vanadium ions, which seriously affects the coulombic efficiency (CE) of the single cell and accelerates the self-discharge rate of the battery. Additionally, the expensive cost of Nafion is also an important reason to limit its large-scale application. In this paper, the dense and low-cost hydrocarbon polymer polybenzimidazole (PBI) is used as the matrix material of the PEM, which is doped with phosphotungstic acid (PWA) to acquire excellent proton conductivity, and the intrinsic high resistance of PBI for vanadium ions is helpful to obtain high proton/vanadium selectivity. Considering the enormous water solubility of PWA and its easy leaching from membrane, organic polymer nano-Kevlar fibers (NKFs) are utilized as the anchoring agent of PWA, which achieves good anchoring effect and solves the problem of the poor compatibility between inorganic anchoring agent and the polymer matrix. The formation of PWA functionalized NKFs was characterized by scanning electron microscope (SEM) and Fourier transform infrared (FT-IR) spectroscopy. The anchoring stability of NKFs for PWA was evaluated by UV-Vis spectroscopy. The characterizations including water uptake, swelling ratio, ion exchange capacity, proton conductivity, vanadium ion permeability and ion selectivity were performed to evaluate the basic properties of the membranes. At the same time, the charge-discharge, self-discharge and cycle performance of single cell assembled with the composite membrane and recast Nafion were tested at various current densities from 40 to 100 mA∙cm^-2. Simple tuning for the filling amount of NKFs@PWA gives the composite membrane superior ion selectivity including an optimal value of 3.26 × 10⁵ S∙min∙cm^-3, which is 8.5 times higher than that of recast Nafion (0.34 × 10⁵ S∙min∙cm^-3). As a result, the VRB single cell assembled with the composite membrane exhibits higher CE and significantly lower self-discharge rate compared with recast Nafion. Typically, the CE of the VRB based on PBI-(NKFs@PWA)-22.5% membrane is 97.31% at 100 mA∙cm^-2 while the value of recast Nafion is only 90.28%. The open circuit voltage (V_OC) holding time above 0.8 V of the single cell assembled with the composite membrane is 95 h, which is about 2.4 times as long as that of recast Nafion-based VRB. The utilization of PBI as a separator for VRB can effectively suppress the penetration of vanadium ions, achieve higher proton/vanadium selectivity and superior battery performance as well as reduce the cost of the PEM, which will play an active role in the promotion of VRB applications.     

Preparation and characterization of quaternized poly (2,2,2‐trifluoroethyl methacrylate‐co‐N‐vinylimidazole) membrane for vanadium redox flow battery

Aiming to develop a suitable ion exchange membrane for vanadium redox flow battery (VRB), a new kind of imidazolium salt type anion exchange membrane based on the copolymer of N‐vinylimidazole and 2,2,2‐trifluoroethyl methacrylate has been prepared. The membrane is characterized by means of water uptake, ion‐exchange capacity, ionic conductivity, and thermal stability. Furthermore, a VRB with this membrane is assembled, and the performance of such VRB is evaluated. The permeability experiments show that this membrane has reasonable low permeability of vanadium ions. The coulombic efficiency (CE) and energy efficiency (EE) of VRB with the synthesized membrane are 99.5% and 75.0%, whereas the CE and EE of the VRB with Nafion® 117 membrane are 82.6% and 72.6%, respectively. The synthesized membrane shows good chemical stability in VRB via more than 4000 cycles test. Therefore, this membrane shows good applicable potential in VRB. Copyright © 2012 John Wiley & Sons, Ltd.     

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。     

Nafion/TiO<Subscript>2</Subscript> hybrid membrane fabricated via hydrothermal method for vanadium redox battery

To improve the performance of Nafion membrane as a separator in vanadium redox battery (VRB) system, a Nafion/TiO₂ hybrid membrane was fabricated by a hydrothermal method. The primary properties of this hybrid membrane were measured and compared with the Nafion membrane. The Nafion/TiO₂ hybrid membrane has a dramatic reduction in crossover of vanadium ions compared with the Nafion membrane. The results of scanning electron microscope, energy dispersive X-ray spectroscopy, and X-ray diffraction of the hybrid membrane revealed that the TiO₂ phase was formed in the bulk of the prepared membrane. Cell tests identified that the VRB with the Nafion/TiO₂ hybrid membrane presented a higher coulombic efficiency (CE) and energy efficiency (EE), and a lower self-discharge rate compared with that of the Nafion system. The CE and EE of the VRB with the hybrid membrane were 88.8% and 71.5% at 60 mA cm⁻², respectively, while those of the VRB with Nafion membrane were 86.3% and 69.7% at the same current density. Furthermore, cycling tests indicated that the Nafion/TiO₂ hybrid membrane can be applied in VRB system.     

表面修饰模式对Nafion离子选择性影响及在VRFB中的应用

本文采用壳聚糖-磷钨酸层对Nafion膜表面分别进行单面和双面修饰改性,研究了修饰模式对Nafion膜钒离子渗透率、电导率及离子选择性的影响. 结果表明,单面、双面修饰改性均会使Nafion膜的钒离子渗透率显著降低,最高降幅分别达到89.9% (单面修饰) 和92.7% (双面修饰);单面、双面修饰改性均会使Nafion膜的电导率下降,但存在明显差异,在相同修饰厚度条件下,双面修饰改性对Nafion膜电导率的影响比单面修饰改性更小。因此,双面修饰复合膜展示出了比单面修饰复合膜更高的离子选择性,并且在修饰层厚度为17 μm时达到最大值（1.12×10⁵ S•min•cm^-3）. 基于优化的双面修饰Nafion膜的全钒液流电池,在充放电流密度30 mA•cm^-2 时,库伦效率和能量效率分别达到93.5%和 80.7%, 并且在测试时间内展示出良好的循环稳定性.     

Nano oxides incorporated sulfonated poly(ether ether ketone) membranes with improved selectivity and stability for vanadium redox flow battery

Three kinds of sulfonated poly(ether ether ketone) (SPEEK)/nano oxide (Al₂O₃, SiO₂, and TiO₂) composite membranes are fabricated for vanadium redox flow battery (VRFB) application. The composite membranes with 5 wt% of Al₂O₃, SiO₂, and TiO₂ (S/A-5 %, S/S-5 %, and S/T-5 %) exhibit excellent cell performance in VRFB. Incorporation of nano oxides (Al₂O₃, SiO₂, and TiO₂) in SPEEK membrane improves in aspect of thermal, mechanical, and chemical stabilities due to the hydrogen bonds’ interaction between SPEEK matrix and nano oxides. The energy efficiencies (EEs) of composite membranes are higher than that of Nafion 117 membrane, owing to the good balance between proton conductivity and vanadium ion permeability. The discharge–capacity retentions of composite membranes also overwhelm that of Nafion 117 membrane after 200 cycles, indicating their good stability in VRFB system. These low-cost SPEEK/nano oxide composite membranes exhibit great potential for the application in VRFB.     

A Cost‐effective Nafion Composite Membrane as an Effective Vanadium‐Ion Barrier for Vanadium Redox Flow Batteries

Ion exchange membranes play a key role in all vanadium redox flow batteries (VRFBs). The mostly available commercial membrane for VRFBs is Nafion. However, its disadvantages, such as high cost and severe vanadium‐ion permeation, become obstacles for large‐scale energy storage. It is thus crucial to develop an efficient membrane with low permeability of vanadium ions and low cost to promote commercial applications of VRFBs. In this study, graphene oxide (GO) has been employed as an additive to the Nafion 212 matrix and a composite membrane named rN212/GO obtained. The thickness of rN212/GO has been reduced to only 41 μm (compared with 50 μm Nafion 212), which indicates directly lower cost. Meanwhile, rN212/GO shows lower permeability of vanadium ions and area‐specific resistance compared to the Nafion 212 membrane due to the abundant oxygen‐containing functional groups of GO additives. The VRFB cells with the rN212/GO membrane show higher Coulombic efficiencies and lower capacity decay than those of VRFB cells with the Nafion 212 membrane. Therefore, the cost‐effective rN212/GO composite membrane is a promising alternative to suppress migration of vanadium ions across the membrane to set up VRFB cells with better performances.     

Sulfonated poly(ether ether ketone)/polyaniline composite proton-exchange membrane

Sulfonated poly(ether ether ketone) (PEEK) was prepared by sulfonation of commercial Victrex^@ PEEK and degree of sulfonation was found to be about 44.5% by ¹H NMR. Sulfonated PEEK/polyaniline composite membranes, in order to prevent methanol crossover, were prepared by chemical polymerization of a thin layer of polyaniline (PANI) in the presence of a high oxidant concentration on a single face modification. FTIR and PANI coating density studies confirmed the loading of PANI in sulfonated PEEK membrane matrix. PANI composite membranes with different polymerization time were prepared and subjected to thermogravimetric analysis as well as electrochemical and methanol permeability study to compare with sulfonated PEEK and Nafion 117 membrane. Ion-exchange capacity, water uptake, proton transport numbers and proton conductivities for different PANI composite sulfonated PEEK (SPEEK) membranes were found to be dependent on the coating density of the PANI in the membrane matrix and were slightly lower than that of Nafion 117 membrane. Methanol permeability of these membranes (especially SPEEK/PANI-1.5) was about four times lower than Nafion 117 membrane. Among the all SPEEK membranes synthesized in this study, SPEEK-1.5 appears to be more suitable for direct methanol fuel cell (DMFC) application considering optimum physicochemical and electrochemical properties, thermal stability as well as very low methanol permeability. Above all, the cost-effective and simple fabrication technique involved in the synthesis of such composite membranes makes their applicability quite attractive.     

磷钨酸/磺化聚醚醚酮质子导电复合膜

直接甲醇燃料电池(Direct methanol fuelcell,DMFC)作为各种用途的可移动动力源具有高效、清洁和燃料储运方便等优点,成为20世纪90年代以来研究与开发的热点。目前,这种电池的研究难点主要集中在催化剂不稳定和质子交换膜透醇上,DMFC膜不但要可传递质子和绝缘电子,还应具有     

Characterization and performance of proton exchange membranes for direct methanol fuel cell: Blending of sulfonated poly(ether ether ketone) with charged surface modifying macromolecule

Modification of sulfonated poly(ether ether ketone) (SPEEK) membrane was attempted by blending charged surface modifying macromolecule (cSMM). The modified membrane was tested for direct methanol fuel cell (DMFC) application; i.e. a SPEEK/cSMM blend membrane was compared to a SPEEK membrane and a Nafion 112 membrane for the thermal and mechanical stability, methanol permeability, and proton conductivity. Thermal and mechanical stability of the blended membrane were slightly reduced from the SPEEK membrane but still higher than the Nafion 112 membrane. The blend membrane was found to be promising for DMFC applications because of its lower methanol diffusivity (2.75 × 10⁻⁷ cm² s⁻¹) and higher proton conductivity (6.4 × 10⁻³ S cm⁻¹), than the SPEEK membrane. A plausible explanation was given for the favorable effect of cSMM blending.     

磺化聚醚醚酮膜的制备及其阻醇和质子导电性能

直接甲醇燃料电池 (Ｄｉｒｅｃｔｍｅｔｈａｎｏｌｆｕｅｌｃｅｌｌ,ＤＭＦＣ)以高效、清洁和燃料储运方便等优点适宜于作为各种用途的可移动动力源 ,成为 2 0世纪 90年代以来研究与开发的热点[1,2 ] .目前 ,这种电池的研究难点主要集中在催化剂不稳定和质子交换膜透醇上 .一张好的ＤＭＦＣ膜不但要可传递质子、绝缘电子 ,还应具有良好的阻醇性能 .如果膜的阻醇性能不好 ,甲醇会穿过膜到达阴极 ,与氧直接反应而不产生电流 ,不但造成燃料的浪费 ,同时也影响阴极的正常反应 ,使电池效率下降[3] .目前广泛应用于燃料电池中的Ｎａｆｉｏｎ系列膜…     

SPEEK/PES-C、SPEEK/SPES-C共混质子交换膜研究

通过在磺化聚醚醚酮(SPEEK,DS=61.68%)中分别混入酚酞型聚醚砜(PES-C)、磺化酚酞型聚醚砜(SPES-C,DS=53.7%)制备出SPEEK/PES-C、SPEEK/SPES-C共混质子交换膜.结果表明,共混的两种聚合物之间均具有较好的相容性.PES-C、SPES-C的混入能有效降低膜的溶胀及甲醇透过,且随着共混量的增加,这种作用越趋明显.纯SPEEK膜在75℃左右溶解,而SPEEK/PES-C(30wt%)、SPEEK/SPES-C(30wt%)共混膜在80℃时溶胀度仅为22.5%、26.32%.在室温至80℃范围内,纯SPEEK及共混膜的甲醇透过系数都在10-7cm2.s-1数量级上,远小于Nafion115膜.在饱和湿度下,温度大于90℃时,SPEEK/PES-C(20wt%)共混膜电导率超过Nafion115膜;温度大于110℃时,SPEEK/SPES-C(30wt%)共混膜电导率与Nafion115膜相当,达到0.11S.cm-1.高电导率,低透醇系数以及明显提高了的可使用温度表明该类共混膜有望在DMFC中使用.     

Sulfonated poly(phthalazinone ether sulfone) membrane as a separator of vanadium redox flow battery

To develop a novel and low-cost membrane as a separator of vanadium redox flow battery, sulfonated poly(phthalazinone ether sulfone) (SPPES) was prepared by sulfonating PPES with fuming sulfuric acid. By testing the sulfonation degree, intrinsic viscosity, and solubility of SPPES, the results showed that sulfonated polymers had higher intrinsic viscosities and excellent solubility in most polar solvents. IR analysis revealed that the –SO₃H group was successfully attached to SPPES backbone. DSC and TG results showed that SPPES exhibited higher T _g than that of PPES, and T _d at the first weight loss of SPPES was about 300?°C. The SPPES membrane (SP-02) showed a dramatic reduction in crossover of vanadium ions across the membrane compared with that of the Nafion membrane. Cell tests identified that VRB with the SPPES membrane exhibited a lower self-discharge rate, higher coulombic efficiency (92.82%), and higher energy efficiency (67.58%) compared with the Nafion system. Furthermore, cycling tests indicated that the single cell with SPPES membrane exhibited a stable performance during 100?cycles.     

DMFC用PES/SPEEK共混阻醇质子交换膜

将磺化聚醚醚酮(SPEEK, 磺化度DS为68.3%)和聚醚砜(PES)两种聚合物共混制得PES/SPEEK共混膜. DSC研究表明两种聚合物之间具有较好的相容性, 因而共混膜均匀致密, 未发生大尺度相分离. PES的混入能有效降低膜的溶胀度及甲醇透过系数. 纯SPEEK 膜40 ℃时在1 mol•L−1甲醇水溶液中溶胀度达到160%, 45 ℃时就完全溶解, 而含30%(w)PES的共混膜在80 ℃时的溶胀度仅有15%. 室温下含20%−30%(w)PES的共混膜的甲醇透过系数为1×10−7 cm2•s−1左右, 比Nafion 115膜的透过系数小一个数量级. 尽管80 ℃下30%(w)PES/SPEEK共混膜的电导率与Nafion 115膜相当, 但由于共混膜的厚度比Nafion 115膜小1/3左右, 膜电阻较小, 因而其电池性能比Nafion 115膜的好.     

磺化双酚芴型聚醚醚酮质子交换膜的制备及其在钒流电池中的应用

以双酚芴为结构单元合成双酚型聚醚醚酮聚合物,聚醚醚酮经浓硫酸磺化在双酚芴结构单元中引入磺化基团制备出聚醚醚酮质子交换膜(SF-PEEK)。 用傅里叶变换红外光谱(FTIR)、核磁共振氢谱(¹H NMR)、热重分析(TG)、原子力显微镜(AFM)和扫描电子显微镜(SEM)等方法对聚醚醚酮质子交换膜的结构进行表征。 结果表明,磺酸基团被成功地在聚醚醚酮侧基上,SF-PEEK膜具有明显的亲水疏水微相分离形貌,磺酸基团相互聚集成形成离子通道。 SF-PEEK膜离子交换容量(IEC)达到1.97 mmol/g时,其电导率达到4.15×10^-2 S/cm,略低于Nafion117膜的5.67×10^-2 S/cm,但其钒离子渗透率仅为Nafion117膜的20.1%,表现出极好的离子选择性。 在钒流电池测试中,SF-PEEK膜在不同电流密度下库伦效率均高于Nafion117膜,其中IEC为1.97 mmol/g的SF80-PEEK608(80为SF的物质的量分数,608为60 ℃反应8 h)库伦效率在电流密度为40 mA/cm²时达到最大值80.9%,高于Nafion117膜的78.8%。 在自放电测试中,以SF80-PEEK608膜组装的电池的自放电时间为90 h,高于Nafion117膜的57 h。     

DMFCs用磺化聚醚醚酮/功能化二氧化硅复合质子交换膜

在磺化度(DS)为55.1%的磺化聚醚醚酮(SPEEK)中掺杂功能化二氧化硅(吸湿性SiO2溶胶及带有磺酸基团的二氧化硅(SiOx-S)粒子)制备SPEEK/SiO2和SPEEK/SiOx-S复合质子交换膜.SiO2和SiOx-S的掺杂能有效提高复合膜的抗溶胀、阻醇性能及高温低湿情况下的电导率.纯SPEEK膜在80℃溶胀为52.6%,而SiO2和SiOx-S掺杂量为15%的复合膜在此温度下分别仅有26.2%和27.3%的溶胀.在室温至80℃范围内,SPEEK/SiO2(20 wt%)和SPEEK/SiOx-S(20 wt%)复合膜的甲醇透过系数比Nafion115膜小近2个数量级.在120℃、相对湿度(RH)为40%情况下,SPEEK纯膜的电导率仅为2.6×10-4S.cm-1,SPEEK/SiO2(20 wt%)复合膜约为2.0×10-3S.cm-1,而SPEEK/SiOx-S(20 wt%)复合膜高达1.0×10-2S.cm-1,与Nafion115相当.SPEEK/SiO2(20 wt%)和SPEEK/SiOx-S(20 wt%)2种复合膜的尺寸稳定性较高,膜电极无催化剂与膜分离现象,其DMFCs单电池性能好于SPEEK膜.