连续共价有机框架筛分复合膜及全钒电池性能

设计了应用于全钒液流电池的尺寸筛分效应共价有机框架/聚醚砜(COF/PES)复合膜,利用纳米片的有序交错堆叠在聚醚砜支撑层上构建了具有均匀埃米级离子传输通道的连续COF分离层。连续COF层的规整刚性骨架赋予了膜极低的溶胀比,有序的埃米级孔道(有效孔径约为0.6 nm)对氢/钒离子具有精确的尺寸筛分作用。COF/PES筛分复合膜的钒渗透率仅有0.61×10^-8 cm^-2·s^-1,质子/钒离子选择性为Nafion 212的4.0倍。电流密度为80 mA·cm^-2下复合膜的能量效率达到82.9%,优于Nafion 212(81.2%)。100 mA·cm^-2下的长循环测试中,复合膜电池容量保持率相比于Nafion 212电池提高了16.2%,表明连续COF/PES筛分复合膜在全钒液流电池中具有广阔的应用前景。     

UH004-Nafion复合质子交换膜研究

将Nafion溶液与溶剂的混合液涂覆在UH004纳滤膜上,制成Nafion/UH004复合膜用于全钒液流电池(VRB)中。该复合膜涂覆的Nafion溶液为400μL,测试其H/V离子选择性系数和电池性,结果均优于UH004。     

全钒液流电池用多氟聚噁二唑芳醚阴离子交换膜的制备

离子交换膜的钒离子渗透是制约全钒液流电池效率的因素之一。制备了一种新型的、低钒离子渗透的氟化聚芳醚阴离子交换膜。以六氟双酚A、四甲基联苯二酚、含氟单体合成了多氟聚噁二唑芳醚。以N-溴代丁二酰亚胺（NBS）为溴化试剂,过氧化二苯甲酰（BPO）为引发剂,将多氟聚噁二唑芳醚上的甲基进行溴化、功能化得到多氟聚噁二唑芳醚阴离子交换膜（QFOAEM）。研究了该膜的钒离子渗透率、离子传导率、吸水率、溶胀度和离子交换容量（IEC）等性能。研究结果表明：QFOAEM的钒离子渗透率为1.1×10^-8cm²·min^-1,低于Nafion117的3.8×10^-7cm²·min^-1,具有在全钒液流电池中应用的潜力。     

A novel anion exchange membranes with fluorinated poly（aryl ether oxadiazole）s ionomer for all-vanadium redox flow battery

离子交换膜的钒离子渗透是制约全钒液流电池效率的因素之一。制备了一种新型的、低钒离子渗透的氟化聚芳醚阴离子交换膜。以六氟双酚A、四甲基联苯二酚、含氟单体合成了多氟聚噁二唑芳醚。以N-溴代丁二酰亚胺（NBS）为溴化试剂,过氧化二苯甲酰（BPO）为引发剂,将多氟聚噁二唑芳醚上的甲基进行溴化、功能化得到多氟聚噁二唑芳醚阴离子交换膜（QFOAEM）。研究了该膜的钒离子渗透率、离子传导率、吸水率、溶胀度和离子交换容量（IEC）等性能。研究结果表明：QFOAEM的钒离子渗透率为1.1×10^-8cm²·min^-1,低于Nafion117的3.8×10^-7cm²·min^-1,具有在全钒液流电池中应用的潜力。     

二元醇共价交联羧基化石墨烯复合膜和正丁醇脱水性能

以二元醇(乙二醇、1,3-丙二醇和1,4-丁二醇)为交联剂,通过抽滤的方式在涂覆盐酸多巴胺的聚醚砜(PES)支撑层上制备了共价交联的羧基化石墨烯/聚醚砜(CG/PES)复合膜。稳定性测试证明盐酸多巴胺的涂覆和二元醇的交联显著提高了分离层和支撑层以及CG纳米片间的结合力。采用扫描电子显微镜、X射线衍射仪、X射线光电子能谱仪和水接触角测试仪对复合膜的物化性质和微观形貌进行了表征。结果表明,所得复合膜的分离层连续无缺陷,厚度在60～64nm之间。二元醇与CG纳米片上的羧基成功发生反应,将CG纳米片锚固在一起。交联剂的引入没有大幅降低亲水性且实现了对分离层层间距的有效调控,随二元醇分子尺寸增加,所得复合膜的层间距由0.761nm提高到0.778nm。CG/PES复合膜对正丁醇/水混合物具有优良的渗透汽化分离性能。在料液温度为50℃、料液中水的质量分数为10%时,三种交联剂所得复合膜的渗透通量分别达到0.79kg/(m²·h)、0.87kg/(m²·h)和0.96kg/(m²·h),而分离因子比未交联的复合膜高一个数量级。15天的...     

PES/Nafion复合膜的制备及其在全钒液流电池中的应用

通过相转移法成功制备了PES/Nafion复合膜,测试了膜的性能和由该膜组装的钒电池的性能。实验发现,用PVP调孔制备的PES/Nafion多孔复合膜的孔径可以调,其中由10%的PVP制得的复合膜组装的钒电池的库伦效率CE为96.7%,能量效率EE值为88.6%,电压效率VE值为97.8%,均优于纯PES多孔膜,可见PES/Nafion复合多孔膜在钒电池中有很大的发展前景。     

锑离子添加剂对低共熔溶剂(DES)电解液液流电池的性能改善研究

非水系氧化还原液流电池（NARFB）的广泛应用受制于其较低的性能。在电解液中加入一些金属离子添加剂是一种可能的解决方案。实验研究了Sb³⁺离子对低共熔溶剂（DES）电解液液流电池电化学性能的影响。结果表明,添加Sb³⁺离子可以强化V（Ⅲ）/V（Ⅱ）氧化还原离子对的电化学反应动力学（最高可达22.6％）过程,钒离子在DES中的扩散系数提高了63.3％,并且电荷转移电阻降低了11.9％。场发射扫描电子显微镜表明,Sb³⁺离子电沉积在石墨毡的表面,对电化学反应起催化作用,从而改善了电化学性能。考虑增强的动力学和降低的活性比表面积之间的平衡,确定了Sb³⁺的最佳浓度为15 mmol·L^-1。此外,当使用含有Sb³⁺的负极电解液液流电池时,液流电池的功率密度提高了31.2%,从含原始电解质的3.08 mW·cm^-2到含15 mmol·L^-1 Sb³⁺离子的4.04 mW·cm^-2。这些结果为改善NARFB的电池性能提供了一个便捷而有前景的方法。     

全钒液流电池用SPEEK／PES共混膜的制备

通过将PES掺入高磺化度的SPEEK进行共混改性,采用流延法制备了一系列不同PES含量的SPEEK／PES共混膜,获得了SPEEK／PES共混膜的离子交换容、含水率、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（IV）离子渗透率。综合考察发现,当磺化温度为45℃,磺化时间控制为4h,得到SPEEK的DS为55％,掺入10％的PES,此时共混膜的电导率为0．08S／cm,钒（IV）离子渗透率为0．38×10^-6cm2／min,对钒（IV）离子选择性为Nation膜的5倍,含水率为35％,共混膜综合性能最好,基本满足全钒液流电池（VRB）的使用需求。     

全钒液流电池VO2+离子跨膜渗透行为

采用静止型全钒氧化还原液流电池,利用紫外分光光度法,研究电解液钒离子跨膜渗透行为,讨论浓度、温度、荷电状态(SOC)、电场以及渗透压等对VO²⁺离子跨膜传质的影响,关联相应的钒离子渗透系数。研究结果表明,提高钒电解液浓度可以有效减缓钒离子跨膜传递速率,提高能量效率;适当降低体系温度,可以抑制钒离子的跨膜渗透,减小电池化学短路的发生;VO²⁺离子渗透系数随SOC值增加而迅速减小;正向电场存在会促进VO²⁺离子透膜扩散,加剧电池自放电;隔膜两侧液面渗透压的作用会加速钒离子跨膜渗透,造成电池容量衰减。     

磁电复合场下正极钒离子的跨膜传质

探究了全钒液流电池在外加磁场、电场、磁电复合场下正极电解液中的钒离子在Nafion117膜上的跨膜传质过程,以及在磁电复合场下硫酸浓度和电解液添加剂对传质过程的影响。根据达西定律拟合得出相应的扩散传质系数。实验结果表明正向电场会加剧钒离子渗透,且当电场强度达到30 V·m^-1时渗透情况严重可达到无电场时的2.53倍。非匀强磁场的加入可明显降低钒离子的跨膜渗透性。且当外加磁场和电场复合场时,磁场对降低钒离子跨膜渗透的作用更加显著。实验还得出在不同的外加复合场中较高浓度硫酸有利于降低钒离子的跨膜渗透。此外丙三醇、木质素磺酸钠正极电解液添加剂的加入也降低了VO₂⁺的跨膜渗透性。     

A new long-side-chain sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)/polybenzimidazole (PBI) amphoteric membrane for vanadium redox flow battery

A new amphoteric membrane was prepared by blending long-side-chain sulfonated poly(2,6-dimethyl-1,4-phenylene oxide)(S-L-PPO) and polybenzimidazole(PBI) for vanadium redox flow battery(VRFB) application.An acid–base pair structure formed between the imidazole of PBI and sulfonic acid of S-L-PPO resulted in lowered swelling ratio. It favors to reduce the vanadium permeation. While, the increased sulfonic acid concentration ensured that proton conductivity was still at a high level. As a result, a better balance between the vanadium ion permeation(6.1 × 10-9 cm~2·s~(-1)) and proton conductivity(50.8 m S·cm~(-1)) in the S-L-PPO/PBI-10% membrane was achieved. The VRFB performance with S-L-PPO/PBI-10% membrane exhibited an EE of 82.7%, which was higher than those of pristine S-L-PPO(81.8%) and Nafion 212(78.0%) at 120 m A·cm~(-2). In addition, the S-LPPO/PBI-10% membrane had a much longer self-discharge duration time(142 h) than that of Nafion 212(23 h).     

MOF-801 polycrystalline membrane with sub-10 nm polymeric assembly layer for ion sieving and flow battery storage

Molecular sieving metal–organic framework (MOF) polycrystalline membranes have great potential for ion sieving and are desirable as efficient separators for devices of energy storage such as flow battery. Herein, we report a continuous MOF-801 polycrystalline membrane with an ultrathin polymeric assembly layer (less than 10 nm) for the vanadium flow battery (VFB). Owing to the precise sub-nanometer sieving pores and abundant H-bond networks in MOF-801 frameworks, the membrane exhibited better H/V selectivity (up to 194) and conductivity (about 0.028 S/cm) than commercial Nafion-117 membrane (H/V selectivity: ~9.5, conductivity: 0.017 S/cm). VFB results revealed that a cell with above MOF polycrystalline membrane showed high coulombic efficiency (CE: 96.1%) and excellent energy efficiency (EE: 83.2%) at 20 mA/cm², which was much comparable to Nafion membrane. This work demonstrates that MOF polycrystalline membrane is a promising candidate as ion sieving membrane for energy technique.     

全钒液流电池用非氟咪唑型阴离子交换膜的制备

在全钒电池(VFB)用离子交换膜中,阴离子交换膜以其钒离子渗透率低这一主要优势受到了广泛的关注。以N-溴代丁二酰亚胺(NBS)为溴化试剂,2,2'-偶氮二异丁腈(AIBN)为引发剂,对聚苯醚(PPO)的苄甲基溴化;以N-正丁基咪唑为功能化试剂,制备了一种非氟咪唑型聚苯醚阴离子交换膜。研究了不同N-正丁基咪唑功能化程度的阴离子交换膜的离子传导率、离子交换容量(IEC)、含水率、钒离子传递系数等性能,并与N-甲基咪唑功能化的阴离子交换膜做了对比。结果显示,N-正丁基咪唑功能化聚苯醚阴离子交换膜的钒离子传递系数为4.8×10^-9 cm·min^-1,60℃时离子传导率为10.8 mS·cm^-1,且化学稳定性及力学性能优异,具有在钒电池中应用的潜力。     

全钒液流电池用磺化聚芴醚酮质子交换膜的制备及性能

质子交换膜(PEM)作为全钒液流电池(VRFB)的核心组件之一,应当解决成本高昂、合成过程复杂等问题,并具备高质子传导率、低钒离子渗透率、高机械强度和优异化学稳定性等关键性能。本文基于四甲基双酚芴单体通过缩聚反应合成了一系列聚芴醚酮化合物PFEKs,再利用溴代反应将苯甲基功能化为溴甲基,接着通过4-羟基苯磺酸钠的SN₂亲核取代制得了一系列不同离子交换容量的磺化聚芴醚酮聚合物(SPFEKs)。通过溶液浇铸法成膜并酸化,得到一系列新型低成本PEMs。该合成路线的原料来源广泛,价格低廉,不涉及危险的磺化反应,易于工业放大。所得膜都具有良好的机械性能和氧化稳定性,其中SPFEK-40膜具有较高的质子传导率及离子选择性、较低的钒离子渗透率及面电阻,综合性能优异。以SPFEK-40膜组装的VRFB在电流密度为80 mA/cm₂^{时的能量效率}(EE)为88.2%,高于以Nafion 212膜组装的VRFB的84.8%。此外,以SPFEK-40膜组装的VRFB在30次循环后放电容量仅衰减至84.3%,远高于以Nafion 212膜组装的VRFB的66.1%。     

Functional molecular cross-linked zeolite nanosheets heighten ion selectivity and conductivity of flow battery membrane

Membranes with high ion selectivity and conductivity are critical for the wide application of electrochemical energy conversion and storage devices. Herein, functional molecular cross-linked two-dimensional zeolite nanosheets (ZN) with -NH₂ and -SO₃H groups are prepared and incorporated into sulfonated poly (ether ether ketone) (SPEEK) polymer matrix. These embedded nanosheets act as strong barrier to vanadium ions, while their internal pores provide transport channels for protons. In addition, the side functional groups grafted on ZN not only effectively enhance the surface affinity, but also bind and arrange the sulfonic acid groups of the polymer matrix to construct a continuous fast proton transfer pathway along the interface between SPEEK and ZN. Consequently, the hybrid membranes exhibit synchronously enhanced conductive-ion selectivity and impressive performance with coulombic efficiency (CE) of ~99.0% and energy efficiency (EE) of ~85.0% at 120 mA cm⁻², which is much higher than these of pure SPEEK (CE: ~97.8%, EE: ~78.4%) and Nafion 212 membranes (CE: ~96.3%, EE: ~80.1%). This functional-designed hybrid approach provides a general strategy to develop high-performance proton conductive membranes for energy-related applications.     

Novel amphoteric ion exchange membranes by blending sulfonated poly(ether ether ketone) with ammonium polyphosphate for vanadium redox flow battery applications

A novel amphoteric ion exchange membrane for vanadium redox flow battery (VRFB) was explored by blending sulfonated poly(ether ether ketone) (SPEEK) and ammonium polyphosphate (APP). The high-stability flame retardant of cross-linked APP with a large number of NH₄⁺ groups was first introduced into SPEEK membrane. It was observed that the addition of APP with special structure could achieve a good balance between proton conductivity and vanadium ions permeability. The abundant NH₄⁺ in APP could block the penetration of vanadium ions by Donnan/Manning exclusion effect and ionic crossing networks due to the ionic bonds between cation and anion groups, and specially a small amount of APP within 5% could remarkably improve the proton conductivity of pristine SPEEK membrane might be ascribed to the unique fast proton transport channels formed by hydrogen bond networks and particular micro-phase separation as a result of interaction between SPEEK and APP. When 5% APP was blended, the SPEEK/APP-5% (S/APP-5%) amphoteric membrane showed a higher selectivity of 20.87 × 10⁴ S min/cm³ (with a good proton conductivity of 0.075 S/cm and a lower VO²⁺ permeability of 3.45 × 10⁻⁷ cm²/ min) and presented better thermal and chemical stability compared to Nafion115 and SPEEK membranes. The VRFB single cell assembled with S/APP-5% amphoteric membrane exhibited more excellent performance than that of Nafion115 and pristine SPEEK membranes, which revealed a higher coulombic efficiency of 96.3%–98.3%, comparable voltage efficiency of 88.4%–78.7% and higher energy efficiency of 85.1%–77.4% from 40 to 80 mA/cm², respectively, and showed relatively good stability of the efficiency up to 50 cycles at 60 mA/cm². The results demonstrated that the designed S/APP amphiprotic membrane of outstanding selectivity, high battery efficiency, and good durability is a prospected VRFB separator.