磺化聚酰亚胺酸碱复合膜的制备及其在全钒液流电池中的应用

采用高温一步法合成了一系列不同磺化度的三元共聚磺化聚酰亚胺(SPI),通过控制磺化二胺与非磺化二胺的摩尔比来调节磺化度.选取碱性聚合物聚乙烯吡咯烷酮(PVP)与SPI按质量比1∶9进行共混,制成SPI/PVP酸碱复合膜.对复合膜的吸水率、离子交换容量、钒离子渗透率以及电池性能进行了测试.结果表明,随着磺化度的升高,复合膜的吸水率、离子交换容量、质子电导率升高以及钒离子渗透率升高.复合膜的隔膜选择性比Nafion117的选择性好,其中SPI/PVP-3的选择性是Nafion117的10倍.电池性能测试表明,随磺化度的升高,复合膜能量效率升高.其中SPI/PVP-3膜较Nafion117膜具有较高的库伦效率和能量效率,通过循环测试SPI/PVP-3膜性能稳定,充放电理想.     

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.     

表面修饰模式对Nafion离子选择性影响及在VRFB中的应用（英文）

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17μm时达到最大值(1.12×105S·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,库仑效率和能量效率分别达到93.5%和80.7%,并在测试时间内展示出良好的循环稳定性.     

全钒氧化还原液流电池用Nafion/有机硅复合膜

采用原位化学反应的方法制备了Nafion/有机硅复合膜, 并对所制备复合膜的离子交换容量(IEC)、电导率和水渗透率等进行了测试. 结果表明, 所制备复合膜具有优异的阻水性能. 以Nafion/有机硅复合膜作为离子交换膜的钒电池的库仑效率(CE)和能量效率(EE)都得到了大幅度提高. 此外, 以所制备复合膜为离子交换膜的VRB单电池充放电80次后性能几乎无衰减, 说明所制备Nafion/有机硅复合膜即使在强酸和强氧化性的钒电池体系中也可以稳定使用, 表明Nafion/有机硅复合膜是一种性能优异的适用于全钒氧化还原液流电池的新型质子交换膜.     

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。     

磺化聚醚醚酮与氧化石墨烯共混膜的制备以及在全钒液流电池中的应用

以浓硫酸为溶剂和磺化剂制备磺化度(DS)为65%的磺化聚醚醚酮(SPEEK),根据SPEEK和氧化石墨烯(GO)不同质量比制备一系列共混膜(S/GO).对共混膜的含水量、离子交换容量、面电阻、质子电导率、钒离子渗透率、机械强度以及耐氧化性进行研究.采用扫描电子显微镜(SEM)观察S/GO共混膜的形态;通过热重分析(TG)表征共混膜的热稳定性.结果表明随着GO引入量的增加,共混膜的含水量增加,离子交换容量(IEC)降低,质子电导率减小,钒离子渗透率减小,机械性能增强.共混膜能量效率均高于Nafion115,其中S/GO-2(GO含量2 wt%)的电池效率最佳,能量效率达到80%,相比于Nafion115提高近9%.在运行100次循环以后S/GO共混膜电池效率稳定性良好.S/GO共混膜有望在全钒液流电池中得到应用.     

SSPEEK/Na-MMT复合钒电池质子交换膜的制备与性能研究

以含有异丙基溴侧基的聚醚醚酮为原子转移自由基聚合(ATRP)大分子引发剂,通过ATRP法在聚醚醚酮主链上接枝引入聚苯乙烯磺酸钠侧链,得到侧链型磺化聚醚醚酮质子交换膜(SSPEEK).采用溶液共混法在SSPEEK膜中引入钠基蒙脱土(Na-MMT),制备SSPEEK/Na-MMT钒电池质子交换复合膜.热重分析表明,复合膜具有较好的耐热性;扫描电镜显示,Na-MMT均匀分散在SSPEEK中.复合膜的钒离子渗透率由SSPEEK膜的1.24×10-5cm2·min-1降为4.88×10-6cm2·min-1,低于Nafion117膜的钒离子渗透率,阻钒能力优于Nafion117膜.电流密度为30 m A·cm-2时,以复合膜组装的电池的放电时间为215 min,长于Nafion117膜的198 min.在高放电电流密度下SSPEEK/Na-MMT膜的库伦效率与Nafion117膜相当.     

钒液流电池用隔离膜研究进展

钒液流电池是近年来发展最为迅猛的储能电池之一。隔膜作为钒电池的重要组成部分直接关系到钒电池的转化储能效率和使用寿命。本文综述了近年来钒电池用隔离膜的发展现状。全氟磺酸质子交换膜(Nafion膜)作为当前使用最为广泛的隔膜,从传导机理、交换机理和表面涂覆、交联、复合等表面改性技术方面入手做了深入的研究,并对比分析了各种改性方法的优缺点。对磺化的特种工程塑料为主的非氟耐热型质子交换膜和功能化的聚烯烃隔膜在钒电池中的当前进展做了全面总结,并对钒液流电池用电池隔膜的发展方向做了展望。     

液流电池用季铵化聚醚砜阴离子交换膜材料的研究

离子交换膜是液流电池的关键部件之一,理想的离子交换膜应具有较低的活性物质渗透率(即有较高的选择性)和较低的面电阻(即有较高的离子传导率),同时还应具有较好的化学稳定性和较低的成本[1,2].目前,全钒液流电池主要采用全氟磺酸类阳离子交换膜(如Nafion),其化学稳定性优异,但易造成钒离子的渗透,降低了电池的使用寿命,且Nafion膜价格昂贵;全钒液流电池的电解质溶液由不同钒电解质溶解在硫酸中组成,采用阴离子交换膜时,由于Donan效应钒离子的渗透将受到制约,与阳离子交换膜相比,具有较高的选择性.     

全钒氧化还原液流电池Nafion/SiO_2复合膜的研究

采用溶胶-凝胶法制备Nafion117/SiO2复合膜.工艺研究表明:复合膜制备过程中,加入的MeOH与TEOS比例基本不影响复合膜的阻钒性能.但如以水解时间10 min,水解完成后自然晾干24 h制备的复合膜,则其VO2+的渗透率最低,为4.27×10-9cm2/s,比Nafion117膜的渗透率降低了52倍.SEM测试表明,经自然晾干的复合膜,其中SiO2晶粒长大,并填充了Nafion膜中大部分的孔洞.以其作隔膜组装全钒氧化还原液流电池(单电池),测试表明膜掺杂后电池的电力效率提高2.7%.     

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.     

Preparation and characterization of Nafion/SPEEK layered composite membrane and its application in vanadium redox flow battery

In order to reduce the cost of membrane used in vanadium redox flow battery (VRB) system while keeping its chemical stability, Nafion/sulfonated poly(ether ether ketone) (SPEEK) layered composite membrane (N/S membrane) consisting of a thin layer of recast Nafion membrane and a layer of SPEEK membrane were prepared by chemical crosslink the sulfonic acid groups of different ionomer membranes. Scanning electron microscopy (SEM) and IR spectra analysis of the membrane showed that Nafion layer was successfully deposited on the SPEEK membrane surface and an integral layered membrane structure was formed. The area resistance and permeability of vanadium ions of membrane were also measured. It was found that N/S membrane have a very low permeability of vanadium ions accompanied by a little higher area resistance compared with Nafion membrane. As a result, the VRB single cell with N/S membrane exhibited higher coulombic efficiency and lower voltage efficiency compared with VRB single cell with Nafion membrane. Although N/S membrane delivered relatively lower energy efficiency compared with Nafion membrane, its good chemical stability and low cost make it a suitable substitute for Nafion membrane used in VRB system.     

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.     

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.     

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.     

Membranes and separators for redox flow batteries

Ion-exchange membranes are performance- and cost-relevant components of redox flow batteries. Currently used materials are largely ‘borrowed’ from other applications that have different functional requirements. The trend toward higher current densities and the complex transport phenomena of the different species in flow batteries need to be taken into consideration for the design of next-generation membrane/separator materials. In this article, the key requirements and current development trends for membranes and separators for the vanadium redox flow battery are highlighted and discussed.     

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。     

SPES/PWA/SiO_2复合质子交换膜的性能

以磺化聚醚砜(SPES)为基体,以不同比例的SiO2溶胶与磷钨酸(PWA)为掺杂物,制备了一种有望用于直接甲醇燃料电池(DMFC)的新型SPES/PWA/SiO2有机-无机复合膜,并经热失重分析(TGA)、差示扫描量热仪(DSC)、扫描电镜(SEM)-X射线能谱分析(EDX)等对膜的结构和性能进行了表征,探讨了复合膜用作质子交换膜的可能性.结果表明:复合膜较纯SPES膜具有更高的热稳定性、玻璃化转变温度和吸水率;虽然在室温和电池操作温度(80℃)下,复合膜的拉伸强度均低于纯SPES膜,但即使当SiO2含量高达20%(w)时,复合膜的拉伸强度仍高于Nafion112膜的;SEM图片显示SiO2和PWA在膜中分布均匀,这将有利于连续质子传输通道的形成.对于SiO2含量为15%(w),PWA含量为6%(w)的复合膜,其室温质子传导率达到了0.034S·cm-1,与Nafion112膜的相当,但其甲醇渗透率明显降低,仅为商用Nafion112膜的七分之一左右,这表明该复合膜在直接甲醇燃料电池中具有良好的应用前景.     

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.