Nafion/silane nanocomposite membranes for high temperature polymer electrolyte membrane fuel cell

The polymer electrolyte membrane fuel cell (PEMFC) has been studied actively for both potable and stationary applications because it can offer high power density and be used only hydrogen and oxygen as environment-friendly fuels. Nafion which is widely used has mechanical and chemical stabilities as well as high conductivity. However, there is a drawback that it can be useless at high temperatures (> or = 90 degrees C) because proton conducting mechanism cannot work above 100 degrees C due to dehydration of membrane. Therefore, PEMFC should be operated for long-term at high temperatures continuously. In this study, we developed nanocomposite membrane using stable properties of Nafion and phosphonic acid groups which made proton conducting mechanism without water. 3-Aminopropyl triethoxysilane (APTES) was used to replace sulfonic acid groups of Nafion and then its aminopropyl group was chemically modified to phosphonic acid groups. The nanocomposite membrane showed very high conductivity (approximately 0.02 S/cm at 110 degrees C, <30% RH).     

Nafion and modified-Nafion membranes for polymer electrolyte fuel cells: An overview

Polymer electrolyte fuel cells (PEFCs) employ membrane electrolytes for proton transport during the cell reaction. The membrane forms a key component of the PEFC and its performance is controlled by several physical parameters, viz. water up-take, ion-exchange capacity, proton conductivity and humidity. The article presents an overview on Nafion membranes highlighting their merits and demerits with efforts on modified-Nafion membranes. Energy security refers to various security measures that a given nation, or the global community as a whole, must carryout to maintain an adequate energy supply     

Antioxidant technology for durability enhancement in polymer electrolyte membranes for fuel cell applications

While polymer electrolyte membrane fuel cells (PEMFCs) have surged in popularity due to their low environmental impact and high efficiency, their susceptibility to degradation by in-situ generated peroxide and oxygen radical species has prevented their widespread adoption. To alleviate chemical attack on components of PEMFCs, particularly on polymer electrolyte membranes (PEMs), antioxidant approaches have been the subject of enormous interest as a key solution because they can directly scavenge and remove detrimental peroxide and oxygen radical species. However, a consequence is that long-term PEMFC device operation can cause undesirable adverse degradation of antioxidant additives provoked by the distinctive chemical/electrochemical environment of low pH, electric potential, water flux, and ion exchange/concentration gradient. Moreover, changes in the physical state such as migration, agglomeration, and dissolution of antioxidants by mechanical or chemical pressures are serious problems that gradually deteriorate antioxidant activity and capacity. This review presents current opportunities for and limitations to antioxidant therapy for durability enhancement in PEMs for electrochemical device applications. We also provide a summary of advanced synthetic design strategies and in-depth analyses of antioxidants regarding optimizing activity-stability factors. This review will bring new insight into the design to realization of ideal antioxidant nanostructures for PEMs and open up new opportunities for enhancing proliferation of durable PEMFCs.     

聚合物膜燃料电池的发展状况

介绍燃料电池的工作原理、催化剂有效应用、聚合物膜电解质及燃料储存和开发     

燃料电池用碳氢聚合物质子交换膜材料研究进展

以我们在磺化聚酰亚胺和磺化聚硫醚砜方面的研究工作为基础,简要介绍了近年来燃料电池用碳氢聚合物质子交换膜的研究进展,包括各种材料的制备和性能(质子导电率、耐水性、尺寸稳定性、吸水率、甲醇透过率等)研究.此外,还介绍了我们最近发明的一种独特的交联方法,用这种方法所制得的磺化聚酰亚胺和磺化聚硫醚砜交联膜装在单电池上显示出良好...     

Manufacturing methods for metallic bipolar plates for polymer electrolyte membrane fuel cell

The bipolar plate (BP) is one of the main drivers of the polymer electrolyte membrane fuel cell (PEMFC) stack cost, and must also perform some critical functions simultaneously within the stack to ensure the required level of overall performance and durability. Therefore, the choice of material and production method for BPs that will meet the requirements for commercial BPs is crucial in PEMFC development. Compared to other material options such as graphite and composites, metals are more promising for the production of durable, thin, light, and low-cost BPs. However, there is still a need to reduce their processing cost through the development of cost-effective and mass production-friendly forming techniques that will not jeopardize the performance and durability of the formed plates. This paper discusses the various currently available fabrication methods for metallic BPs, with attention to their potentials for mass production and capabilities to produce plates that meet the performance and cost targets of commercial PEMFC BPs. In prospects of development drivers going forward, the potentials of hydroforming to outperform stamping for mass production of low-cost metallic plates are discussed. Current limitations facing high-quality metallic BP production and research trends are also highlighted.     

Composite endplates with pre-curvature for PEMFC (polymer electrolyte membrane fuel cell)

A conventional PEMFC (polymer electrolyte membrane fuel cell) stack is composed of multiple stack composed of GDL (gas diffusion layer), MEA (membrane electrode assemblies), and bipolar plates sandwiched in between two thick metallic endplates tightened by bands or tie-bolts as to maintain proper contact pressure on its active area and gasket interface. The proper contact pressure distribution in a stack offers low contact resistance for high energy efficiency and fluid leakage prevention as well. For which, the endplates should have proper structural stiffness.     

原位聚合法制备Nafion(R)/PANI复合膜及其在DMFC中的应用

用0.1 mol/L (NH4)2S2O8/1 mol/L盐酸溶液作引发剂,采用原位化学聚合的方法将苯胺单体聚合在Nafion(R) 112膜基体中.扫描电镜(SEM)和能谱(EDX)测试结果表明,复合膜的表面和Nafion(R) 112膜相比有明显变化,苯胺主要聚合在膜的两侧.复合膜的红外光谱中出现明显聚苯胺(PAN...     

Graphene-based bipolar plates for polymer electrolyte membrane fuel cells

Bipolar plates (BPs) are a major component of polymer electrolyte membrane fuel cells (PEMFCs). BPs play a multifunctional character within a PEMFC stack. It is one of the most costly and critical part of the fuel cell, and hence the development of efficient and cost-effective BPs is of much interest for the fabrication of next-generation PEMFCs in future. Owing to high electrical conductivity and chemical inertness, graphene is an ideal candidate to be utilized in BPs. This paper reviews recent advances in the area of graphene-based BPs for PEMFC applications. Various aspects including the momentous functions of BPs in the PEMFC, favorable features of graphene-based BPs, performance evaluation of various reported BPs with their advantages and disadvantages, challenges at commercial level products and future prospects of frontier research in this direction are extensively documented.     

Recent developments in polymer electrolyte membrane-based fuel cells

Here, we round up some recent developments in polymer electrolyte (proton-exchange) membrane-based fuel cell technology.     

Corrosion protection of CrN/TiN multi-coating for bipolar plate of polymer electrolyte membrane fuel cell

The electrochemical corrosion cells will be generated from the possible pinholes of the promising CrN and TiN coatings in a PEMFC environment. To prevent the elution of possible pinholes, CrN/TiN multi-coatings on SS have been considered. This study examined the electrochemical behavior of three CrN/TiN coatings on 316L stainless steel deposited at different CrN/TiN thickness ratios by rf-magnetron sputtering as potential bipolar plate materials. Potentiodynamic tests of CrN/TiN-coated 316L stainless steel carried out in a 1 M H₂SO₄ + 2 ppm HF solution at 70 °C revealed a significantly lower corrosion current density than that of uncoated 316L SS, as well as a decrease in the corrosion current density with decreasing inner-layer CrN thickness. Electrochemical impedance spectroscopy also showed that the CrN/TiN-coated 316L SS sample had higher charge transfer resistance than the uncoated 316L SS sample, which increased with decreasing inner-layer CrN thickness. This was attributed to the crystalline-refined CrN/TiN(200).     

Near-infrared imaging of water in a polymer electrolyte membrane during a fuel cell operation

A novel technique of spectroscopic imaging using a near-infrared (NIR) laser sheet beam was developed for visualization of liquid water in a proton-exchange membrane (PEM) sandwiched between two opaque electrodes set in a polymer electrolyte fuel cell (PEFC). In-plane two-dimensional distribution of water in the thin membrane was clearly visualized during the fuel cell operation. Under the condition of fuel feeding into the PEFC without humidification, water was generated by the fuel cell reaction in the whole electrode area. In contrast, under the condition of fuel feeding with humidification, the PEM got wet in the vicinity of a gas flow field locally.     

直接挥发法制备无纺布增强型聚合物电解质

以N,N-二甲基-甲酰胺(DMF)为溶剂, 采用直接挥发法制备无纺布增强型聚偏氟乙烯-六氟丙烯(PVDF-HFP)聚合物电解质, 并以锂为负极制备了聚合物电池.用扫描电子显微镜、交流阻抗和循环伏安对所制聚合物膜性能进行了表征,用充放电实验对所制聚合物电池电化学性能进行了测试.实验结果表明,直接挥发法制得的聚合物膜孔穴丰富,微孔呈蜂窝状,吸液率为280%,电化学稳定窗口为4.5V,浸取电解液后室温离子电导率为1.5mS/cm;以LiCoO2为正极制得的聚合物电池0.1C充放电, 放电平台为3.9V左右, 首次放电容量为137.5mAh/g,20次循环后容量保持在134mAh/g以上,充放电库仑效率高于95%,0.5C放电时放电平台为3.7V,0.5和1C放电分别能保持0.1C放电容量的96%和93%.     

Electrochemical properties of TiN coatings on 316L stainless steel separator for polymer electrolyte membrane fuel cell

TiN films for metallic bipolar plates were synthesized by closed-field unbalanced magnetron sputtering (CFUBM) and the properties were controlled by adjusting the N₂ partial pressure. The corrosion behaviors of TiN films were investigated by potentiodynamic tests and electrochemical impedance spectroscopy (EIS) measurements under the condition of an aerated 1 M H₂SO₄ + 2 ppm HF solution at 70 °C with a constant potential of 600 mV_SCE. The results revealed that the variation of N₂ pressure had an influence on the corrosion resistance of TiN coating. N₂ partial pressure of 0.4 mTorr showed good corrosion resistance with the lowest corrosion current density and the highest charge transfer resistance due to the low porosity.     

Effect of bias voltage on the electrochemical properties of TiN coating for polymer electrolyte membrane fuel cell

The electrochemical properties of TiN film coated on AISI 316 stainless steel (SS) by the magnetron sputtering physical vapor deposition (PVD) were studied for application as a bipolar plate. The crystal structure and surface morphology of the coatings were examined by x-ray diffractometry (XRD) and atomic force microscopy (AFM), respectively. The corrosion behaviors of the TiN films were investigated by electrochemical methods, including potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) under + 600 mV_SCE application. The electrochemical behavior of the TiN coatings was enhanced with increasing bias voltage due to lower corrosion current density and higher R_ct values during an immersion time of 168 h. This result was attributed to the formation of crystalline-refined TiN(200) at high bias voltage, which increased the coating compactness and the protective efficiency, and decreased passive current density.