Review on ion exchange membranes for vanadium redox flow battery applications

全钒氧化还原液流电池(VRB)作为一种新兴的电化学储能系统在解决可再生能源利用方面具有良好的应用前景.离子交换膜作为全钒液流电池的关键功能材料之一,应具有钒离子透过率低,电导率高,化学稳定性好等性能.本文论述了VRB的工作原理和特点,综述了近年来国内外相关的研究进展,对商品化离子膜,新型阳离子膜,新型阴离子膜,两性离子膜在VRB中的研究应用进行了对比与分析,并指出它们各自需要改进的地方;最后提出应大力开发低成本的国产全氟磺酸离子膜,为实现VRB大规模的产业化奠定基础.     

液流电池储能技术研究现状与展望

液流电池技术利用流动的电解液作为电化学储能介质,适合于进行大容量电能与化学能的转化与储存。液流电池通常具有寿命长、效率高等技术特征,在平滑风能、太阳能等可再生能源发电出力以及微型电网、智能电网建设等方面有着广阔的应用前景。本文论述了液流电池的研究与开发现状,概述了目前逐渐具备工程实施能力的全钒液流电池体系,分析了液流电池新体系的研究开发状况,指明了它们各自需要进行技术突破的重要问题,最后展望了金属/ 空气液流电池的技术优势与未来发展前景。     

木质素磺酸钠作为全钒液流电池添加剂的研究

摘要〖HTSS〗：采用电化学方法分析了不同含量木质素磺酸钠对钒电池正极电解液的影响。交流阻抗、紫外可见光谱和单电池充放电实验验证了木质素磺酸钠添加后的效果。分析结果表明：添加量为0.1% 时,电荷传递电阻由5.446Ω·cm2 减小到1.002Ω·cm2 ,双电层电容由4.16×10-4F·cm-2 减小到1.298×10-4F·cm-2 ,添加不同含量的木质素磺酸钠并没有显著影响激发态波长和吸光度,但是充放电性能显著提高,这表明木质素磺酸钠具有很强的化学及电化学稳定性,有利于提高钒离子的传导和电能的储存。     

全钒氧化还原液流电池一体化复合电极的研究

采用改性处理的聚丙烯腈基石墨毡和聚合物为基体的碳塑板制备得到了钒电池用一体化复合电极.研究表明,聚丙烯腈基石墨毡经过400～450℃、2 h的热处理和98%浓硫酸中浸泡6 h的酸处理后具有较好的催化活性.用以聚醋酸乙烯乳液占总原料的70%,而活性炭和石墨粉占30%(活性炭:石墨粉=1:1)的比例压制的碳塑板、改性处理后的石墨毡及不锈钢网组成一体化复合电极,循环伏安测试表明此一体化复合电极具有较好的电化学活性.     

聚合物电解质膜中质子输送过程的Monte Carlo模拟

模拟了质子在质子交换膜中的输送过程.通过构造新模型,研究了质子数等因素对质子在质子交换膜中输送过程的影响.有实验资料表明质子在膜中的大多数输送是链段运动和质子跃迁双重作用的结果,利用模拟参数本文将输送的质子数表征为链段运动和质子跃迁两项和的形式.随着质子浓度的增加,质子输送数随之增加,达一定值后又随之下降.同时质子输送数随着链段长度、链数、总链段浓度等的增加而增加.而随着链段运动恢复时间的相对增加,质子的跃迁数略有下降.此外,随链容纳质子数的增加,可运动质子数随之增加,达一定值后渐达平衡值.这些结论与文献报道的实验结果基本相符.     

掺杂纳米SiO2粉末的微孔型聚合物电解质研究

用萃取法制备了偏二氟乙烯 六氟丙稀共聚物( P ( VdF HFP))为基质, 1mol/L 的 LiPF6/EC/DMC/DEC 溶液为液体电解质的微孔型聚合物电解质。测试结果表明:室温电导率最大值达 4.38×10-3S/cm;扫描电镜(SEM)和 X 射线衍射分析(XRD)结果表明电解质膜为非晶态的多孔结构;差示扫描(DSC)结果表明在-50~76℃温度范围内膜电解质膜为无定形态;其电化学稳定性窗口为5V。     

Ionic Nanosystems: Large Space‐Charge Effects in a Nanostructured Proton Conductor (Adv. Funct. Mater. 23/2010)

Decreasing the dimensions of heterogeneous mixtures of ionic conductors towards the nanoscale results in ionic conduction enhancements, caused by the increased influence of the interfacial space‐charge regions. For a composite of TiO₂ anatase and solid acid CsHSO₄, the strong enhancement of the ionic conductivity at the nanoscale also can be assigned to this space‐charge effect. Surprisingly high hydrogen concentrations in the order of 10²¹ cm^?3 in TiO₂ are measured, which means that about 10% of the available sites for H⁺ ions are filled on average. Such high concentrations require a specific elaboration of the space‐charge model that is explicitly performed here, by taking account of the large occupation numbers on the exhaustible sites. It is shown that ionic defects with negative formation enthalpy reach extremely high concentrations near the interfaces and throughout the material. By performing first‐principles density functional theory calculations, it is found that proton insertion from CsHSO₄ into the TiO₂ particles is preferred compared to neutral hydrogen atom insertion and indeed that the formation enthalpy is negative. Moreover, the average proton fractions in TiO₂, estimated by the theoretical ionic density profiles, are in good agreement with the experimental observations.     

Fungal and bacterial mediated denitrification in wetlands: Influence of sediment redox condition

Fungal and bacterial denitrification rates were determined under a range of redox conditions in sediment from a Louisiana swamp forest used for wastewater treatment. Sediment was incubated in microcosms at 6 Eh levels (−200, −100, 0, +100, +250 and +400 mV) ranging from strongly reducing to moderately oxidizing conditions. Denitrification was determined using the substrate-induced respiration (SIR) inhibition and acetylene inhibition methods. Cycloheximide (C₁₅H₂₃NO₄) was used as the fungal inhibitor and streptomycin (C₂₁H₃₉N₇O₁₂) as the bacterial inhibitor. At Eh values of +250 mV and +400 mV, denitrification rates by fungi and bacteria were 34.3-35.1% and 1.46-1.59% of total denitrification, respectively, indicating that fungi were responsible for most of the denitrification under aerobic or weakly reducing conditions. On the other hand, at Eh −200 mV, denitrification rates of fungi and bacteria were 17.6% and 64.9% of total denitrification, respectively, indicating that bacteria were responsible for most of the denitrification under strongly reducing conditions. Results show fungal denitrification was dominant under moderately reducing to weakly oxidizing conditions (Eh > +250 mV), whereas bacterial denitrification was dominant under strongly reducing condition (Eh < −100 mV). At Eh values between −100 to +100 mV, denitrification by fungi and bacteria were 37.9-43.2% and 53.0-51.1% of total denitrification, respectively, indicating that both bacteria and fungi contributed significantly to denitrification under these redox conditions. Because N₂O is an important gaseous denitrification product in sediment, fungal denitrification could be of greater ecological significance under aerobic or moderately reducing conditions contributing to greenhouse gas emission and global warming potential (GWP).     

氧化电解水杀菌特性及其对肉品杀菌作用

利用自制三室型电解槽制备酸性氧化电位水(EOW),并对自制的钽铱氧化物电极进行了XRD、SEM和电化学分析。以枯草杆菌黑色变种芽孢（ATCC9372）为杀灭对象,考察影响EOW杀菌作用的三个特性因素,即有效氯(ACC)、氧化还原电位(ORP)和pH值。结果表明,利用自制三室型电解槽制备氧化电解水(EOW),对自制铱氧化物电极进行了XRD、SEM表征和电化学分析。以枯草杆菌黑色变种芽孢（ATCC9372）为杀灭对象,考察了影响EOW杀菌作用的3个因素,即有效氯(ACC)、氧化还原电位(ORP)和pH值。结果表明,ACC值越高,EOW的杀菌效率越高,当ACC值大于40 mg.L^-1时,杀菌效率进一步提高缓慢,最大杀菌率为99.89%,杀灭对数值为2.67lgcfu.ml^-1。EOW中有效氯存在形式以HClO为主,这也是EOW具有高效杀菌作用的原因。随ORP值增加,杀菌效率也随之增加,但当其大于1100 mV后,杀菌率和杀灭对数值进一步增加较少,可分别达到99.99%和3.86lgcfu.ml^-1。pH值本身对杀菌效率影响很小,但pH值改变会影响有效氯的存在形式。考察了EOW对肉品的杀菌效果,结果表明当EOW与肉品接触后,其ACC值、ORP值会迅速下降,1 min后分别由78.60 mg.L^-1和1132mV降低到47.35 mg.L^-1和935 mV;25 min后降低至11 mg.L^-1和815 mV,此时EOW已失去高效杀菌能力。EOW对肉品杀菌20 min后,杀菌率为99.96%,杀灭对数值为3.42lgcfu.g^-1。     

氢气扩散阳极电解铝技术研究进展

高能耗、高污染是Hall-Heroult铝电解槽无法克服的先天不足.氢气扩散阳极(HDA)电解铝方法无论在能耗还是在排放上,比Hall-Heroult铝电解槽或者是其它技术有明显的优势.它已经在冶金、燃料电池等领域得到广泛的应用并且取得了较好的节能与环保效果.氢气扩散阳极在电解铝领域应用的难点在于,探寻合适的气体-电极-电解质系统和有效控制HF排放.基于吉布斯自由能的化学反应动力学仿真分析为解决这些问题提供了便利.研究表明,Ni合金可能可以胜任电极材料的要求;而合理设计阳极结构,迅速转移主反应中生成的水蒸汽,可以较好地解决HF排放问题.