Search results

The purpose of this paper is to improve the surface electrical conductivity and corrosion resistance of AISI 430 stainless steel (430 SS) as bipolar plates for proton exchange membrane fuel cells (PEMFCs), a protective Nb-modified layer is formed onto stainless steel via the plasma surface diffusion alloying method. The effect of diffusion alloying time on electrochemical behavior and surface conductivity is evaluated.

In this work, the surface electrical conductivity and corrosion resistance of modified specimen are evaluated by the potentiodynamic and potentionstatic polarization tests. Moreover, the hydrophobicity is also investigated by contact angle measurement.

The Nb-modified 430 SS treated by 1.5 h (1.5Nb) presented a lower passivation current density, lower interfacial contact resistance and a higher hydrophobicity than other modified specimens. Moreover, the 1.5 Nb specimen presents a smoother surface than other modified specimens after potentionstatic polarization tests.

The effect of diffusion alloying time on electrochemical behavior, surface conductivity and hydrophobicity of modified specimen is evaluated. The probable anti-corrosion mechanism of Nb-modified specimen in simulated acid PEMFC cathode environment is presented.

The purpose of this paper is to produce electrically conductive, fluid impermeable graphite bipolar plates for a direct methanol fuel cell, using indirect selective laser sintering (SLS) and suitable post processing techniques.

Bipolar plates are made by the indirect SLS of graphite powder and phenolic resin mixture. The phenolic resin binder is then burnt off at a high temperature in a vacuum furnace to produce a 100 per cent carbon part. This brown part is then infiltrated using a low‐viscosity (∼5‐10  cps) cyanoacrylate to seal up the open pores, rendering the plates fluid impermeable.

It has been found that the electrical conductivity increases significantly (> 220 S/cm) with a corresponding increase in pyrolyzing temperature which correlates well with literature on the carbonization of phenol formaldehyde resins. The cyanoacrylate infiltrated parts tested under fluid pressure demonstrated no leakage through the plate, indicating full closure of open porosity.

This work demonstrates the capability of the SLS process to produce working bipolar plates with complex flow field designs that can be tested to verify its efficacy in a working fuel cell, thereby saving time and cost in machining natural graphite.

This paper aims to evaluate corrosion behavior of bare and PbO₂-coated stainless steel 316L, as prospective candidates for bipolar plates, in simulated proton exchange membrane fuel cell’s (PEMFC’s) environment under operating potentials.

A set of potentiodynamic, as well as potentiostatic, electrochemical experiments was carried out under both anodic and cathodic potentials. Gathered data were analyzed via fast Fourier transform algorithm for further investigation. X-ray diffraction analysis was also used for determining coating characteristics upon completion of electrochemical experiments.

Results revealed that bare SS316L is a better candidate for bipolar plate material under anodic potential, as it is cathodically protected. However, PbO₂-coated SS316L is favorable under cathodic potential, as bare specimen will suffer localized corrosion in the form of pitting.

It would be of interest if all the experiments are carried out in a PEMFC stack.

This research strives to promote the use of electrochemical noise measurement for practical corrosion monitoring of coated bipolar plates in fuel cells.

Improving the corrosion resistance of bipolar plates will expedite commercialization of PEMFCs, which in turn will translate into a substantial reduction in carbon footprint.

This research strives to promote the use of electrochemical noise measurement for practical corrosion monitoring of coated bipolar plates in fuel cells.

This study investigated the corrosion stability of high velocity oxy‐fuel (HVOF) spray SUS316L coatings on aluminium substrate as lightweight bipolar plate materials for proton exchange membrane fuel cells (PEMFC). Contact resistance, microhardness and structure of the coatings were characterised using a four‐point probe, pneumatic microhardness, XRD and scanning electron microscope techniques. Preliminary electrochemical results indicate that the SUS316L coated plates significantly lowered the corrosion current of the aluminium substrate by more than one order of magnitude. Corrosion stability in relation to the coating thickness is discussed in terms of the structure composition and transpassivity of chromium.

The purpose of this study is to improve the surface electrical conductivity and corrosion resistance of AISI430 stainless steel (430 SS) as bipolar plates for direct formic acid fuel cell (DFAFC).

The niobium diffusion layers have been successfully synthesized on 430 SS substrate by the plasma surface diffusion alloying technique under different diffusion alloying time.

The surface morphology of Nb-modified 430 SS prepared under the diffusion alloying time of 2 h is more homogeneous, relatively sleek and compact without surface micropore and other common surface blemishes. The potentiostatic and potentiodynamic polarization measurements manifest that Nb-modified 430 SS prepared under the diffusion alloying time of 2 h enormously ameliorate the corrosion resistance of bare 430 SS compared with other Nb-modified 430 SS samples and its corrosion current density is maintained at −1.4 µA cm⁻² in simulated anodic environment of DFAFC (0.05 M H₂SO₄ + 2 ppm HF + 10 M formic acid at 50 °C).

The effect of diffusion alloying time on the corrosion resistance and surface conductivity of Nb-modified 430 SS has been carefully studied. The Nb-modified 430 SS samples prepared at the diffusion alloying time of 2 h have the best surface electrical conductivity and corrosion resistance in the simulated anodic environment of DFAFC.

This paper aims to present a new fabrication method for fuel cell current collectors. Demonstration of its usefulness and discussion of its impact on current collector design and performance are also given.

The selective laser sintering (SLS) technique is used to create green parts followed by a high temperature curing process and pressureless infiltration treatment to meet basic part design requirements.

A material system and process satisfying both manufacturing constraints and product property requirements can be used for fabrication of current collectors via SLS. Relative particle size and composition of the constituents play an important role in successful manufacture of the plates. Strategies to improve electrical conductivity are also discussed.

A new manufacturing method has been developed for the construction of fuel cell current collectors that could generate opportunities for performance enhancement and fuel cell application by eliminating the constraints imposed by traditional fabrication processes.

The purpose of this paper is to investigate the interfacial conductivity and corrosion resistance of the Ni–P/Ti₄O₇ composite coating that is deposited on a carbon steel substrate as bipolar plates for proton exchange membrane fuel cells.

The Ni–P/Ti₄O₇ coating was prepared by electroless plating. Scanning electron microscopy, white light interference, energy dispersive spectrometry and X-ray diffraction were used, respectively, to study the surface morphology, chemical composition and phase composition of coated samples. Electrochemical impedance spectroscopy, potentiodynamic and potentiostatic polarization were used to test the electrochemical performance and corrosion behavior. The interfacial contact resistance (ICR) was measured via the standard method.

The surface of the Ni–P/Ti₄O₇ coating is complete and dense and without obvious defects. The electrochemical test results show that the Ni–P/Ti₄O₇ coating provides better corrosion resistance than the Ni–P coating and substrate. Compared with the Ni–P coating, the ICR of the Ni–P/Ti₄O₇ coating is lower by about 82.7%. This is because the coating has more conductive contact points. The more exciting thing is that the ICR of the Ni–P/Ti₄O₇ coating only increases to 12.38 mΩ·cm² after 5 h of polarization.

This paper provides a method for achieving surface modification of metal bipolar plates. Introducing Ti₄O₇ particles in the Ni–P layer reduces the contact resistance before and after polarization while ensuring good corrosion resistance.

The purpose of this paper is to improve the corrosion resistance of stainless-steel bipolar plate by magnetron sputtering.

TiC/amorphous carbon composite film was deposited by magnetron sputter at four different temperature of 25°C, 200°C, 300°C and 400°C. The morphology, composition and structure of the film were characterized by scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. And its corrosion behavior was analyzed through electrochemical impedance spectroscopy, potentiodynamic and potentiostatic polarization tests.

A compact TiC/amorphous carbon film was prepared by magnetron sputtering on 316L stainless steel, and the particles of the film were refined with the increase in sputtering temperature. High temperature promoted the formation of TiC and C–C sp² hybrid carbon, but excessively high temperature caused the oxidation of Ti and a significant decrease in sp² hybrid carbon. The corrosion resistance of the film increased with the temperature, and the corrosion current density polarization at 0.86 V and 1.8 V for TiC/a–C film prepared at 400 °C is only 1.2% and 43.2% of stainless steel, respectively.

The corrosion resistance of amorphous carbon films was improved by the doping of Ti carbide, and the appropriate sputtering temperature was obtained.

Effective performance of a direct ethanol fuel cell (FC) stack depends on the satisfactory operation of its individual cells where it is always challenging to manage the temperature gradient, water flow and distribution of reactants. In that, the design of the bipolar fuel flow path plate plays a vital role in achieving the aforementioned parameters. Further, the bipolar plates contribute 80% of the weight and 30%–40% of its total cost. Aim of this study is to enhance the efficiency of fuel to energy conversion and to minimize the overall cost of production.

The authors have specifically designed, simulated and fabricated a standard 2.5 × 2.5 cm² active area proton exchange membrane (PEM) FC flow path plate to study the performance by varying the flow fields in a single ladder, double ladder and interdigitated and varying channel geometries, namely, half curve, triangle and rectangle.

Using the 3D PEMFC model and visualizing the physical and electrochemical processes occurring during the operation of the FCs resulted in a better-performing flow path plate design. It is fabricated by using additive manufacturing technology. In addition, the assembly of the full cell with the designed flow path plate shows about an 11.44% reduction in total weight, which has a significant bearing on its total cost as well as specific energy density in the stack cell.

Simultaneous optimization of multiple flow path parameters being carried out for better performance is the hallmark of this study which resulted in enhanced energy density and reduced cost of device production.

The purpose of this paper is to show the main features of the redox flow battery technology, present the current state-of-the-art of both industrial and research systems and to highlight the main research challenges.

The study is based on an extensive survey of recent literature as well as on the authors' own experience in the modelling of RFB systems.

RFBs present unique features which make them suitable for distributed storage and thus particularly interesting in the context of smart grids. Current research aims at resolving some outstanding issues which still limit the widespread use of RFBs.

A more widespread use of energy storage technologies, and RFBs in particular, will allow a much higher penetration of renewable energy sources.

The paper presents one of the few comprehensive studies on RFBs including both technological and modelling aspects.