Plates For Fuel Cells Research Articles

Corrosion Resistance, Cell Performance and Long-term Stability of Metal Bipolar Plates for Direct Methanol Fuel Cell

In this study, we investigated the austenitic stainless steel 316 and the ferritic stainless steel 430, 446, and pure Ti plate as metal bipolar plates for DMFC. This work was carried out to offer fundamental information about metal bipolar plates of DMFC because there are few literatures relevant to the subject. The corrosion behaviors of these metals were studied in the simulated fuel cell environment, and then their single cell performance and long-term stability were tested at real operating conditions of DMFC.

Corrosion Resistance, Cell Performance, and Long-Term Stability of Metal Bipolar Plates for Direct Methanol Fuel Cell

not Available.

Recent development in surface modification of industrial materials by ion beams and plasma at Chiang Mai University

Recently, programs of surface modification of materials for local industries by ion beams and plasma have been vigorously carried out and related facilities, technologies and applications have been continuously developed at Chiang Mai University on the basis of previous work. Some examples are presented. Punching tools from local industry were N-ion implanted with a specially designed process to achieve both high hardness and impact toughness so as to increase the lifetime of the tools by 3–4 times. High-fluence N-ion implantation in stainless steel of the fuel cell plates increased corrosion resistance. Plasma immersion ion implantation and deposition (PIII/D) coated diamond-like carbon (DLC) thin films on various substrate materials such as stainless steel of the fuel cell plates, glass of the plastic lens mould, and magnets of the dental rectification accessories to improve both mechanical and chemical properties. Plasma treatment of commercial textiles modified the wettability of the material. The development in the ion beam and plasma applications for industries has promoted research for understanding physics involved as well as student education of the university.

Characteristics and Preparation of Polymer/Graphite Composite Bipolar Plate for PEM Fuel Cells

A novel concept of composite bipolar plate composed of modified phenolic resin, graphite, and carbon black with thickness less than 2mm has been successfully prepared by the bulk molding process at ambient temperature. This study investigates a potential approach to improve the properties of composite bipolar plate by choosing appropriate graphite particle size distributions and carbon black added means. The effects of resin content, molding pressure, curing temperature, graphite particle size distribution, graphite sorts, and carbon black on the properties of composite bipolar plate have been studied. The optimum processing conditions for preparing composite bipolar plate are: resin content 15—20wt%; molding pressure 10—12MPa; curing temperature 180°C; graphite particle size distribution -200/+325 mesh; carbon black content 4—5 wt%; and carbon black initially dispersed in resin with supersonic purifier. Under optimum conditions, we have produced composite bipolar plate with electrical conductivity higher than 80 S/cm and flexural strength higher than 40 MPa. In addition, this composite bipolar plate was thermally stable from room temperature to 420°C.

A Mathematical Model for the Corrosion of Metallic Bipolar Plates in PEM Fuel Cells: Numerical and Experimental Issues

A two-dimensional mathematical model for corrosion of metallic bipolar plates in a PEM fuel cell (FC) is presented. Numerical approximations by a novel finite difference technique to deal with nonlinear and mixed boundary conditions are illustrated. Numerical computations and comparisons with experimental data obtained with a laboratory PEMFC are reported. Good qualitative agreement of the simulations has been found with the time dependence of the average current density and with the space distribution of the corrosion rate.

Chemical Modification on Stainless Steel as Bipolar Plate of Polymer Electrolyte Membrane Fuel Cell

The stainless steel as bipolar plate has been widely used on polymer electrolyte membrane fuel cell(PEMFC) for its conductivity and anti-corrosion properties.Because of the acid environment in PEMFC,in order to further improve the service life,316L stainless steel is put in the mixed conductive and acidic solution for surface chemical modification.The results indicate that,the contact resistance of 316L SS after passivation can reach 18.5 mΩ·cm2 at least when the pressure achieves 9×105 Pa.Comparing with the 316L SS before passivation,its contact resistance decreases nearly 6 times while the corrosive current changes slightly.Dynamic potential polarization plot shows that,after passivation,the stainless steel improves its self-corrosion potential obviously.A lot of holes can be seen distributing on the surface of the steel under the apparatus of super depth microscope.But after passivation,most of the holes are mantled.

固体高分子形燃料電池セパレータ用ステンレス箔の開発

固体高分子形燃料電池セパレータ用ステンレス箔の開発

Potential applications of amorphous/metallic glassy alloys as hydrogen-permeable membranes for hydrogen production and bipolar plates for PEFC

The potential of amorphous/metallic glassy alloys as hydrogen-permeable membranes for hydrogen production and as bipolar plates for Polymer Electrolyte Fuel Cells (PEFCs) was investigated in this paper. Firstly, the hydrogen permeation of the melt-spun (Ni0.6Nb0.4)70Zr30-xTax (x = 5, 10, 15, 20 at%) alloys was measured. As a result, it was found that the hydrogen permeability of the alloys decreased with the Ta content. However, degradation during the permeation test of the alloy with 10 at%Ta was smaller than that with 5 at%Ta. Therefore, it can be concluded that Ta addition stabilises the permeation behaviour, preventing significant degradation over time, despite the fact that Ta addition does not affect the hydrogen permeability of the alloys. Secondly, the Ni65Cr1515P16B4 metallic glassy alloy was produced by melt-spinning in air. The bipolar plate was successfully produced by hot-pressing with dies in a supercooled liquid state. It was shown that this alloy could be a good candidate for a bipolar plate material for PEFC.

Electrically Conductive CNT/PTFE Composite Film for Corrosion Resistant Coating on Bipolar Plate of Fuel Cell

AbstractComposite film of carbon nanotube (CNT) and polytetrafluoroethylene (PTFE) was formed with despersion fluid of CNT and PTFE. The film showed high electrical conductivity in the range of 5-13S/cm. This conductive film was applied on the stainless steel bipolar plate for the polymer electrolyte membrane fuel cell (PEMFC) as anticorrosion film. This coating decreased the contact resistance between the surface of bipolar plate and the membrane electrode assembly (MEA) of the PEMFC. Therefore, the output power of the fuel cell was increased by 1.6 times.

Three Mechanisms for Protecting the Fuel Cell Membrane, Plates and Catalysts

The performance of the perfluorinated sulfonic acid polymer electrolyte membrane in PEM fuel cells degrades through a multi-step process: (i) hydroxyl radicals attack on the fluorinated polymer with the release of fluoride ions; (ii) corrosion of the plates and alloy catalysts by the fluoride anions, with the release of base metal cations; (iii) generation of more hydroxyl radicals through Fenton's reaction catalyzed by the metal ions. While fluoride ion release can be greatly reduced through the inclusion of cerium, manganese or sodium ions into the PFSA polymer membrane, we present here an alternative approach for mitigating the membrane degradation. We propose three chemical methods for increasing the overall durability of the fuel cell by interfering with each step of this degradation cycle: the uses of (i) hydroquinones, to neutralize hydroxyl radicals, (ii) aza-crowns for sequestering fluoride anions, and (iii) crown ethers to sequester base metal cations.

Improvements of Electrical Properties Containing Carbon Nanotube in Epoxy/Graphite Bipolar Plate for Polymer Electrolyte Membrane Fuel Cells

The epoxy based graphite bipolar plate containing carbon nanotube (CNT) for polymer electrolyte membrane fuel cells (PEMFC) has been prepared and the electrical properties were compared. The density of graphite composite bipolar plate showed from 1.85 to 0.94 as expanded graphite content is increased from 10 to 50 w/o. The improvement of electrical properties was accomplished by addition of CNT. Rapid increase of conductivity was found due to the compensation between increases of the electrical pathway by addition of CNT and sufficient electrical contact among isolated large graphite particle. The polarisation curves of bipolar plate were measured at 1 M H2SO4 solution with 1 mV/sec of scan rate and the value of 1.903 uA/cm2 of corrosion rate was obtained.

Three Mechanisms for Protecting the Fuel Cell Membrane, Plates and Catalysts

not Available.

Development and Characterization of Expanded Graphite-Based Nanocomposite as Bipolar Plate for Polymer Electrolyte Membrane Fuel Cells (PEMFCs)

Expanded graphite-based nanocomposites as bipolar plates for polymer electrolyte membrane fuel cells (PEMFCs) are developed by compression molding technique. The expanded graphite is prepared by chemical intercalation of 50 BS mesh particle size of natural graphite by strong acid. It is found that composite bipolar plate with a varying weight percent of resin and EG gives the high electrical conductivity, competitive mechanical properties with a bulk density of 1.5−1.55 g/cm−3, and air tightness. The EG-based composites with 40−45 wt % of resin are suitable for achieving desired properties of the bipolar plate as per the DOE advanced series target. The addition of 5 wt % of carbon black is helpful for improving the electrical conductivity without compromising other properties of the bipolar plate. The lower value of the modulus of expanded graphite (3−8 GPa) composite as compared to graphite−resin-based composite (>12 GPa) plates attributes that these plates are more flexible and able to withstand shock a...

Life-Limiting Aspects of the Corrosion of Metallic Bipolar Plates for PEM Fuel Cells

In proton exchange membrane fuel cells (PEMFCs), the bipolar plates supply the reactant gases through the flow channels to the electrodes and serve the purpose of electrochemically connecting one cell to another in the electrochemical cell stack. Requirements of the bipolar plate material are: high values of electronic conductivity; high values of thermal conductivity; high mechanical strength; impermeability to reactant gases; resistance to corrosion; and low cost of automated production. Metallic materials meet many of these requirements but the challenge has been in obtaining the required corrosion resistance. In the paper, six metallic materials were investigated as potential bipolar plate materials. The results showed that the corrosion rates were too high even for the most corrosion resistant metals (SS316L and grade 2 Ti), and that coatings would be required.

Micromachining of bipolar plates used in proton exchange membrane fuel cells

Bipolar Proton Exchange Membrane (PEM) fuel cell plates are composed of flat pieces of graphite with channels or trenches machined into the face of the plate so that gases can flow in the channels of the plate. The operation of the fuel cell is dependent on the flow of oxygen and hydrogen gases around a fuel cell stack, which is composed of many thin plates connected to each other in very close proximity. Owing to the brittle nature of graphite, bipolar plates are now made from nickel-chromium alloys that are coated with a thin solid layer of CrN or TiN to improve corrosion resistance. However, nickel-chromium alloys are notoriously difficult to machine. This paper describes the micromachining of fuel cell plates that are machined at very high speeds in order to produce high cutting tool life and low surface roughness using novel nanocrystalline diamond and titanium coatings that have been specifically designed to cut strain-hardening alloys at extremely high speeds.

Bipolar Plates for Fuel Cell

From the viewpoints of volume, cost, quality, and durability, bipolar plate for fuel cell is regarded as one of the very important parts by fuel cell system manufacturers. NISSHINBO INDUSTRIES, INC. has been doing R&D, production, and sales for molded resin/carbon composite bipolar plats (“molded carbon plates”) since 1992. By the joint-development with NESS, Nisshinbo could develop the high-strength biopolar plates with A4 size and 0.2 mm web thickness.

Chemical Treatment of Aluminum Bipolar Plates for PEM Fuel Cells

A major component in PEM cell stack design and performance is the bipolar plates connecting the cells. Although many lightweight bipolar plates have been suggested yet cost and performance remain unresolved. Chemically treated Al was used. The Al substrate is pretreated in Zinc solution before dipping in different concentrations of nickel alloy solutions, mainly Ni-W-P, Ni-Co-P, and Ni-Co-W-P. A series of the coated samples was electroplated using Ni-P solution after electroless coating. The coated samples, where characterized and tested using, SEM, EDAX, Electrical Conductivity, and Electrochemical Corrosion techniques. The effect of changing alloy composition and deposition time on the electrical conductivity and corrosion resistance are reported. The most promising sample was that coated with Ni-Co-P before electroplating, this sample was machined for cross flow gas design and used as a bipolar plate in a PEM cell configuration. I-V performance test was conducted at room temperature and 23.7mA and 640mV with varying resistance. A duration test carried out for a period of 100 hours, showed constant voltage and current throughout the duration period of the test. The interrelations between properties, microstructure, composition, and performance are discussed.

Preparation and Properties of High Performance Nanocomposite Bipolar Plate for Fuel Cell

The thin polymer composite bipolar plates (the thickness < 1.5 mm) for use in polymer electrolyte membrane fuel cells (PEMFCs) containing vinyl ester resin, graphite powder, organoclay have been fabricated by bulk molding compound (BMC) process. Organoclay prepared by ionic exchange of montmorillonite (MMT) with three different Mw of diamine intercalating agents was used to reinforce the mechanical properties of the composite bipolar plates. Results indicate that the basal spacing and content of MMT varied with Mw of POP-diamines are critical in determining the resultant mechanical properties for bipolar plates. The flexural strength and the unnotched impact strength of the plate were ca. 38 % (from 30.21 MPa to 45.66 MPa) and ca. 30 % (from 58.11 J/m to 80.21 J/m) higher than the pristine graphite plate, respectively, as the basal spacing of MMT (2 phr) was increased from 1.71 to 5.43 nm. The limiting oxygen index (L.O.I.) and the UL-94 test revealed that the bipolar plate possesses excellent flame retardant with L.O.I. higher than 50 and UL-94-V0. In addition, the electrical conductivity of the bipolar plates with different MMT contents and basal spacing of MMT is higher than 100 S/cm.

Corrosion Study on Different Types of Metallic Bipolar Plates for Polymer Electrolyte Membrane Fuel Cells

Three different types of metallic bipolar plates (commercial stainless steels, Ni-based alloys, and nitride-coated steels) were investigated in terms of their interface contact resistance (ICR) and corrosion resistance in conditions typical of a proton exchange membrane fuel cell environment. The results showed that stainless steels are unsuitable because of the formation of nonconductive oxide that leads to high ICR. Ni-based alloys showed to be prone to corrosion in acidic medium, although they have an ICR comparable to commercially available graphite. Endurance tests carried out on nitride-coated stainless-steel specimens showed a low ICR and very good corrosion resistance of this material.

Micromilling of bipolar fuel cell plates using titanium- and diamond-coated cutting tools

Bipolar Proton Exchange Membrane Fuel Cell (PEMFC) plates are composed of flat pieces of graphite with channels or trenches machined into the face of the plate so that gases can flow in the channels of the plate. The operation of the fuel cell is dependent on the flow of oxygen and hydrogen gases around the fuel cell stack, which is composed of many thin plates connected to each other in very close proximity. Owing to the brittle nature of graphite, bipolar plates are now made from experimental Nickel–Chromium (Ni–Cr) alloys that are coated with a thin solid layer of CrN or TiN to improve corrosion resistance. However, Ni–Cr alloys are notoriously difficult to machine. This paper describes the micromachining of fuel cell plates that are machined at very high speeds in order to produce high cutting tool life and low surface roughness using novel nanocrystalline diamond and titanium coatings that have been specifically designed to cut strain-hardening alloys at extremely high speeds.