氢能发电技术的研究(Ⅰ)--铂碳复合电极材料对离子交换膜燃料电池放电性能的影响

离子交换膜燃料电池是氢能应用开发的重要研究领域.研究了离子交换膜燃料电池用的铂碳复合电极制备工艺和碳材料的选择对燃料电池电化学性能的影响.研究结果表明,铂碳复合电极的制备工艺对燃料电池放电性能有重要影响,采用刷涂法和物化法制备的铂碳复合电极所组装的燃料电池具有较好的电化学性能.研究结果还发现,复合电极中碳材料的微观结构也是影响燃料电池电化学性能的重要因素,碳材料的比表面积越大,燃料电池的放电性能就越好.     

氢能发电技术的研究（Ⅳ）——电极扩散层对离子膜燃料电池放电性能的影响

研究了电极扩散层对离子膜燃料电池放电性能的影响。结果表明：制备扩散层的基体材料对燃料电池放电性能有较大的影响。本实验所采用的碳纸、碳膜和碳纤维布3种基体材料中,碳纤维布是一种较为理想的基体材料,不同扩散层所组装的燃料电池最大放电功率密度有较大的差别,碳纤维布扩散层所组装的燃料电池最大放电能量分别是碳纸和碳膜扩散层所组装的燃料电池最大放电能量的2.16倍和6.94倍。不同扩散层对燃料电池最佳放电运行时的放电电压和放电电流密度也都有一定的影响,特别是对放电电流密度影响更为强烈,电极扩散层的疏水性是影响燃料电池稳定放电寿命的一个重要因素,因此在电极扩散层的制备和基材选择过程中,必须充分考虑这一因素的影响。     

质子交换膜燃料电池专用碳纸的制备及性能测试

采用湿法造纸技术制备质子交换膜燃料电池电极扩散层专用碳纸材料,考察了影响专用碳纸性能的主要因素。研究结果表明：分散剂、粘合剂和纤维长度等对碳纸物性具有较大影响。以3M的NaOH处理碳纸的基体材料,控制打浆度20°SR,按比例加入自制功能性分散剂,在优化工艺条件下,制备的碳纸物性基本和日本东丽公司产品(Toray碳纸)物性相同。以自制的碳纸和Toray碳纸为电极扩散层基体材料组装成电池,放电性能测试表明,自制碳纸是一种较为理想的燃料电池电极扩散层基体材料。     

氢能发电技术的研究（Ⅱ）——电极添加剂对离子膜燃料电池放电性能 …

离子交换膜电池作为一种理想的氢能发电装置,是目前氢能研究开发的热点。研究了电极添加剂对离子交换膜燃料电池电化学性能的影响。     

氢能发电技术的研究(Ⅱ)--电极添加剂对离子膜燃料电池放电性能的影响

离子交换膜燃料电池作为一种理想的氢能发电装置,是目前氢能研究开发的热点.研究了电极添加剂对离子交换膜燃料电池电化学性能的影响.实验结果表明,离子膜燃料电池的放电电压和电流密度均随电极催化层中PTFE的含量增加而呈起伏变化,在负极催化层PTFE含量为8%,正极催化层PTFE含量为12%-16%时,燃料电池的放电电压和电流密度都处于高峰值状态.实验结果还表明,在电极中加入适量的Nafion乳液可显著地提高电极的电催化反应活性,同时也发现添加不同方法配制的Nafion乳液,对燃料电池放电性能的影响也有一定的差别.     

多级碳复合的大尺寸硅颗粒在锂离子电池负极中的性能北大核心CSCD

以光伏电池生产废料中的大尺寸硅颗粒(200~800 nm)为原料,水性聚氨酯(PU)和聚苯胺(PANI)作为碳源,通过液相包裹法和低温热解法制备了不同结构碳复合的硅碳负极材料(SPU与SPU#PANI),分别研究了复合碳含量、微结构与元素掺杂对负极电化学性能的影响。SPU负极中碳复合量低,首次放电比容量高达2193.6 mAh/g,但循环稳定性差。经二级碳复合后的SPU#PANI导电性提高,在多孔碳微结构支撑作用下,不仅获得了较高的放电比容量(1488.8 mAh/g),而且经100次循环后SPU#PANI放电比容量保持在756.8 mAh/g以上,表现出良好的倍率性能。研究结果表明,大尺寸硅颗粒表面复合了具备多孔结构的碳后,不仅为硅充放电过程中的膨胀提供了缓冲,也为锂离子传输提供通道,有效地提升了硅基负极的电化学性能和稳定性。本工作采用的多级碳低温热解复合方法,可为锂离子电池硅基负极产业化技术发展提供重要的借鉴。     

重力对PEM燃料电池性能的影响

水对质子交换膜(PEM)燃料电池的性能有极其重要的影响,良好的水管理是PEM燃料电池保持高性能的必要条件.通过试验,观察了在重力作用下液态水对PEM燃料电池性能及其内部传质的影响,分析了PEM燃料电池单体电极的不同摆放位置对其性能的影响.试验结果发现:在电流密度较小时,重力对PEM燃料电池性能的影响不明显,电流密度较大时,重力对PEM燃料电池性能的影响比较明显.试验结果对优化PEM燃料电池的结构和水管理有一定的参考价值.     

氢能发电技术的研究（Ⅲ）—离子交换膜对离子膜颜料电池放电性能的影响

测试分析了3种不同离子交换膜材料的水存留量,溶涨率和离子导电率,结果表明水存留量的膜材料溶涨率和离子导电离也相应较大,对不同离子交换膜的耐热和耐压稳定性测试结果发现3种离子交换膜在200℃以下范围内都没有发生相变或其它结构性变化,失重率都低于5％,因此3种膜材料在200℃以下温度范围内使用是安全可靠的,不同膜材料的耐压机械强度均随着热压处理温度升高而逐渐下降,在相同热压温度条件下的耐压强度的,SH117B膜大于或等于Nafion117膜,Nafion117膜大于或等于SH117A膜,离子交换膜也是影响燃料电池放电性能的一个重要因素,Nafion117组装的燃料电池最大放电功率密度分别是SH117A膜和SH117B膜组装的燃料电池最大放电功率密度的1．28倍和2．4倍。     

Developments of electrodes for vanadium redox flow battery

本文介绍了钒液流电池电极材料的研究现状。详细介绍了电极种类、电极材料的改性途径、改性效果,并对电极的老化机制进行了分析。全钒液流电池（VFB）电极材料改性的方法主要包括增加电极催化活性和增大电极电化学反应面积两种方式。通过对电极进行热处理、酸处理,可以改变电极表面结构,提高电极催化活性,从而提高电极反应可逆性。通过在电极表面生长碳纳米管或者负载石墨烯、氧化铱等而制备的复合电极材料,以及采用天然废弃物制备的多孔碳电极,可以达到同时提高电极表面催化活性和增大电极电化学反应面积的效果。还可以通过制备电极和双极板复合一体化电极,降低电池的接触电阻,减小电池极化。而电极的化学降解及电化学降解对于电极的寿命会产生影响,而且对电池负极的影响比正极更加明显。最后,总结了VFB电极材料的现状并展望了未来研究发展的方向。     

静电纺丝法制备硅碳纳米纤维及其在锂钠离子电池中的应用

静电纺丝法由于具有工艺简单、功能多样等优点,是一种重要的制备一维锂钠离子电池纳米结构电极材料的方法。目前,已有大量利用静电纺丝技术制备高性能电极材料的研究报道,但具有系统性和针对性的综述论文尚十分有限。碳材料是最早被研究且已实现商业化的锂离子电池负极材料,硅材料则是理论容量最高的负极材料,因此,两者一直是学术界和工业界关注的重点;但碳材料理论容量低和硅材料体积变化大的问题严重阻碍了各自更广泛的实际应用。静电纺丝技术被证明是一种可以解决上述问题的十分有效的方法。因此,本文系统地综述了静电纺丝法制备的硅基和碳基纳米纤维在锂钠离子电池负极材料上的应用和发展,重点从静电纺丝原理、硅碳材料的设计及合成、结构的调控与优化、复合材料的制备到电化学性能的提高等方面作了详细介绍和讨论,同时也指出静电纺丝法在大规模生产中的不足及未来可能的发展方向。希望此综述可以为先进储能材料（尤其是硅基和碳基纳米电极材料）的设计和制备提供一些有益的指导和帮助。     

Novel quaternized polysulfone/ZrO2 composite membranes for solid alkaline fuel cell applications

A novel composite anion exchange membrane, zirconia incorporated quaternized polysulfone (designated as QPSU/ZrO₂), is prepared by solution casting method. The characteristic properties of the QPSU/ZrO₂ composite polymer membranes are investigated by thermogravimetric analysis, X-ray diffraction and electrochemical impedance spectroscopy. The morphology of the composite membrane is observed by SEM and TEM studies. A study of an alkaline membrane fuel cell (AMFC) operating with hydroxide ion conducting membrane is reported. Evaluation of the fuel cell is performed using membrane electrode assemblies made up of carbon supported platinum (Vulcan XC-72) anode and platinum cathode catalysts and QPSU/ZrO₂ composite membrane. Experimental results indicate that the AMFC employing a cheap non-perflourinated (QPSU/ZrO₂) composite polymer membrane shows better electrochemical performance. The maximum power density observed is 250 mW/cm² for QPSU/10% ZrO₂ at 60 °C. The QPSU/ZrO₂ composite membrane constitutes a good candidate for alkaline membrane fuel cell applications.     

Allotrope carbon materials in thermal interface materials and fuel cell applications: A review

The performance of allotrope carbon materials has been explored because of their superior properties in energy system applications. This review provides an understanding of the current work focusing on the applications of selected carbon materials in important energy systems, focus on thermal interface materials (TIMs), and fuel cell applications. This article begins with the introduction of TIMs and fuel cell in general working principle and presents details on carbon materials. The discussion focuses on updates from the latest research work and addresses current challenges and opportunities for research toward TIMs and fuel cell applications. The optimum performance of TIMs was seen when thermal conductivity achieved at a maximum of 3000 W (m K)⁻¹ by using vertically aligned carbon nanotubes (CNTs) and a minimum internal thermal resistance of 0.3 mm² K W⁻¹. Meanwhile for fuel cell, the platinum/CNTs catalyst applied proton exchange membrane fuel cell achieved high power density of 661 mW cm⁻² in the presence of Nafion electrolyte membrane. This review provides insights for scientists about the use of carbon materials, especially in energy system applications.     

Recent progress in nitrogen-doped carbon and its composites as electrocatalysts for fuel cell applications

The emergence of fuel cell technology has created a new tool for the generation of clean, high efficiency alternative energy for humans. The research and development of new catalysts to replace the expensive and rare platinum (Pt) to reduce the overall cost of fuel cells is ongoing in this area. Nitrogen-doped carbon and its composites possess great potential for fuel cell catalyst applications especially at the oxygen reduction cathode. It is proposed that the reaction mechanisms of nitrogen-doped carbon catalysts for oxygen reduction involve adsorption of oxygen at the partially polarised carbon atoms adjacent to the nitrogen dopants, different from the mechanism at platinum catalysts, which utilise d-bands filling at oxygen adsorption sites. Nitrogen doping in both carbon nanostructures and its composites with active metals or ceramics are reviewed. Nitrogen-doped carbon without composite metals, displays high catalytic activity in alkaline fuel cells and exhibits significant activity in proton exchange membrane fuel cells and direct methanol fuel cells. Pt-based catalysts with nitrogen-doped carbon supports show enhanced catalytic activity towards oxygen reduction, attributed to the enhanced anchoring of Pt to the support that results in better dispersion and stability of the electrodes. For nitrogen-doped carbon composites with non-noble metals (Fe, Co, etc), enhanced activity is seen in both proton exchange and alkaline fuel cells. There are many ongoing debates about the nature of nitrogen-carbon bond in catalysis. Pyrrole- and pyridinic-type nitrogen generally considered to be responsible for the catalytic sites in acidic and alkaline media, respectively. In recent years, significant efforts have been made towards increasing the stability of nitrogen-doped carbon catalysts in acidic media through the formation of composites with ceramic or metal oxide materials. This article reviews the progress in the area of this new class of catalysts and their composites for greater enhancement of oxygen reduction activity and stability in various fuel cell applications.     

Screening of recycled membrane with crystallinity as a fundamental property

The maximum cost incurred in building a Polymer Electrolyte Membrane fuel cell (PEMFC) can be attributed to the proton exchange membrane and platinum on carbon (PtC) catalyst. Recycling of these precious components after their life, has been speculated to increase the commercial viability of PEMFC. In this work, we have demonstrated a method of recycling membranes from end of life fuel cells, with low input energy and bereft of any HF gas emission, and also amenable for up-scale activity. Further, to date most of the research work on recycling have focused mainly on the procedure to extract the membrane and no correlation on understanding the condition of the membrane for reusability or recyclability has been reported. In this work, we have developed a relationship between the structural properties of the recycled membrane to the overall electrochemical performance, helpful in predicting the end application.     

Alkaline fuel cell technology - A review

The realm of alkaline-based fuel cells has with the arrival of anionic exchange membrane fuel cells (AEMFCs) taken a great step to replace traditional liquid electrolyte alkaline fuel cells (AFCs). The following review summarises progress, bottleneck issues and highlights the most recent research trends within the field. The activity of alkaline catalyst materials has greatly advanced, however achieving long-term stability remains a challenge. Great AEMFC performances are reported, though these are generally obtained through the employment of platinum group metals (PGMs), thus emphasising the importance of R&D related to non-PGM materials. Thorough design strategies must be utilised for all components, to avoid a mismatch of electrochemical properties between electrode components. Lastly, AEMFC optimisation challenges on the system-level will also have to be assessed, as few application-size AEMFCs have been built and tested.     

Recent advances in hybrid support material for Pt‐based electrocatalysts of proton exchange membrane fuel cells

Proton exchange membrane fuel cell is an energy conversion technology with an excellent potential to replace fossil fuel–based internal combustion engines. Evenly distributed Pt on conductive support is commonly used as an electrocatalyst. This catalyst support material is a key component of proton exchange membrane fuel cell as it greatly affects the cost, durability, and electrochemical activity of fuel cells. Although the carbon‐based support materials have evolved in the last few decades, there is still need to explore other alternatives as the corrosion of carbon is inevitable under the harsh environments within the catalyst layer of proton exchange membrane fuel cells. Moreover, the performance of noncarbon supports is also not satisfactory. Therefore, the advent of hybrid support materials, which are electrochemically stable and cost‐effective, is required. The hybrid supports exhibiting the characteristics of contributing component, or even showing synergistic effect, would circumvent the shortcomings associated with individual components. This review introduces the recent advances in hybrid support materials, including carbonaceous and noncarbonaceous one; discusses the pros and cons of different support materials; and highlights the improved properties of hybrid supports as compared with the individual components.     

Introducing a novel technique for measuring hydrogen crossover in membrane-based electrochemical cells

Hydrogen crossover that is the unwanted hydrogen permeation across the membrane driven by the difference of gas concentrations causes a critical concern of safety and efficiency for electrochemical cells, such as fuel cells and electrolyzer cells. Although the hydrogen crossover measurement in fuel cells that employ platinum based catalysts is simple and widely used in laboratory settings, it is questionable to apply existing limiting current method to water electrolyzer cells and alkaline exchange membrane (AEM) systems, which is due to the typical catalyst materials used and membrane properties, respectively. In this work, we demonstrate the operation of a compact and low-cost method of measuring hydrogen crossover that works for both AEM and proton exchange membrane (PEM) systems. The method entails a tandem configuration that utilizes an upstream crossover cell with a downstream cell in hydrogen pump configuration to measure the crossover in the cell of interest. We have successfully measured the hydrogen crossover with different membranes at various differential pressures. The developed method can be applied to catalyst-free membranes (both PEM and AEM) as well as PGM free catalyst containing cells. It will be a promising technique for measuring hydrogen crossover in-situ for a real operating membraned-based electrochemical cell or stack.     

The preparation technique optimization of epoxy/compressed expanded graphite composite bipolar plates for proton exchange membrane fuel cells

Vacuum resin impregnation method has been used to prepare polymer/compressed expanded graphite (CEG) composite bipolar plates for proton exchange membrane fuel cells (PEMFCs). In this research, three different preparation techniques of the epoxy/CEG composite bipolar plate (Compression-Impregnation method, Impregnation-Compression method and Compression-Impregnation-Compression method) are optimized by the physical properties of the composite bipolar plates. The optimum conditions and the advantages/disadvantages of the different techniques are discussed respectively. Although having different characteristics, bipolar plates obtained by these three techniques can all meet the demands of PEMFC bipolar plates as long as the optimum conditions are selected. The Compression-Impregnation-Compression method is shown to be the optimum method because of the outstanding properties of the bipolar plates. Besides, the cell assembled with these optimum composite bipolar plates shows excellent stability after 200 h durability testing. Therefore the composite prepared by vacuum resin impregnation method is a promising candidate for bipolar plate materials in PEMFCs.