Stamping is a critical step in the manufacture of metallic bipolar plates.Typically,residual stress and a spring back effect appear on the bipolar plate after the stamping process,which impacts on the performance and ...Stamping is a critical step in the manufacture of metallic bipolar plates.Typically,residual stress and a spring back effect appear on the bipolar plate after the stamping process,which impacts on the performance and lifetime of the proton exchange membrane fuel cell(PEMFC).The residual stress and spring back behavior which occur as a result of stamping a bipolar plate are investigated in this study.The effects of the punch radius,the die radius,the channel depth,and the clearance between the punch and the die on the residual stress and forming quality of the bipolar plate are examined.The stamping process can be divided into three stages.The high stress area and the middle section residual stress area were selected to study the formation process and to obtain the composition of the residual stress regions.Spring back was mainly related to the position of the fixed end of the sheet and the degree of plastic deformation,and the sheet thickness have increased by 2μm after spring back.Based on the results of finite element analysis,as described by the distribution of residual stress,the formation,the thickness of the middle cross section and the equivalent plastic strain,it was found that all the tool parameters affected the distribution of the residual stress.This research can provide a design reference for the manufacture of metallic bipolar plates based on the stamping process.展开更多
In the realm of proton exchange membrane fuel cells(PEMFCs),the bipolar plates(BPs)are indispensable and serve pivotal roles in distributing reactant gases,collecting current,facilitating product water removal,and coo...In the realm of proton exchange membrane fuel cells(PEMFCs),the bipolar plates(BPs)are indispensable and serve pivotal roles in distributing reactant gases,collecting current,facilitating product water removal,and cooling the stack.Metal BPs,characterized by outstanding manufacturability,cost-effectiveness,higher power density,and mechanical strength,are emerging as viable alternatives to traditional graphite BPs.The foremost challenge for metal BPs lies in enhancing their corrosion resistance and conductivity under acidic conditions,necessitating the application of various coatings on their surfaces to ensure superior performance.This review summarizes and compares recent advancements in the research of eight distinct types of coatings for BPs in PEMFCs,including noble metal,carbide,ni-tride,and amorphous carbon(a-C)/metal compound composite coatings.The various challenges encountered in the manufacturing and fu-ture application of these coatings are also delineated.展开更多
In view of the M_(n+1)AX_(n)(MAX)phase coatings benefting the adaptive passivation flm for good corrosion resistance and high electronic density of states for excellent electrical conductivity,here,we reported the Cr_...In view of the M_(n+1)AX_(n)(MAX)phase coatings benefting the adaptive passivation flm for good corrosion resistance and high electronic density of states for excellent electrical conductivity,here,we reported the Cr_(2)Al C MAX phase coatings with different preferred orientations by a homemade technique consisting of vacuum arc and magnetron sputtering.The dependence of surface and interface microstructural evolution upon the corrosion and electrochemical properties of deposited coating was focused.Results showed that all the Cr_(2)Al C coatings with different phase orientations greatly improved the performance of stainless steel(SS)316 L substrate.Specifcally,the lowest value of interface contact resistance(ICR)reached to 3.16 mΩcm^(2)and the lowest corrosion current density was 2×10^(-2)μA cm^(-2),which were much better than those of bare SS316L.The combined studies of electrochemical properties and theoretical calculations demonstrated that the Cr_(2)Al C coatings with preferred(103)orientation were easier to form oxide passivation flm on their surface to increase the corrosion resistance.展开更多
Proton exchange membrane(PEM)fuel cells have significant potential for clean power generation,yet challenges remain in enhancing their performance,durability,and cost-effectiveness,particularly concerning metallic bip...Proton exchange membrane(PEM)fuel cells have significant potential for clean power generation,yet challenges remain in enhancing their performance,durability,and cost-effectiveness,particularly concerning metallic bipolar plates,which are pivotal for lightweight compact fuel cell stacks.Protective coatings are commonly employed to combat metallic bipolar plate corrosion and enhance water management within stacks.Conventional methods for predicting coating performance in terms of corrosion resistance involve complex physical-electrochemical modelling and extensive experimentation,with significant time and cost.In this study machine learning techniques are employed to model metallic bipolar plate coating performance,diamond-like-carbon coatings of varying thicknesses deposited on SS316L are considered,and coating performance is evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy.The obtained experimental data is split into two datasets for machine learning modelling:one predicting corrosion current density and another predicting impedance parameters.Machine learning models,including extreme gradient boosting(XGB)and artificial neural networks(ANN),are developed,and optimized to predict coating performance attributes.Data preprocessing and hyperparameter tuning are carried out to enhance model accuracy.Results show that ANN outperforms XGB in predicting corrosion current density,achieving an R2>0.98,and accurately predicting impedance parameters with an R2>0.99,indicating that the models developed are very promising for accurate prediction of the corrosion performance of coated metallic bipolar plates for PEM fuel cells.展开更多
Bipolar plates perform as current conductors between cells, provide conduits for reactant gases, facilitate water and thermal management through the cells, and constitute the backbone of a fuel cell stack. Currently, ...Bipolar plates perform as current conductors between cells, provide conduits for reactant gases, facilitate water and thermal management through the cells, and constitute the backbone of a fuel cell stack. Currently, commercial bipolar plates are made of graphite composite because of its relatively low interfacial contact resistance (ICR) and high corrosion resistance. However, graphite composite’s manufacturability, permeability, and durability of shock and vibration are unfavorable in comparison to metals. Therefore, metals have been considered as a replacement material for graphite composite bipolar plates. The main objective of this study is to evaluate the effect of terminal connection design and bipolar plate material on PEM fuel cell overall performance. The study has indicated that single cell performance can be improved by combining terminals into metallic bipolar plates. This terminal design reduces the internal cell resistance and eliminates the need for additional terminal plates. The improved single cell performance by 18% and the increased savings in hydrogen consumption by 15% at the current density of 0.30 A/cm2 was attributed to the robust metal to metal contact between the terminal and the metallic bipolar plates. However, connecting metal terminal directly into graphite bipolar plates did not exhibit similar improvement in the performance of graphite fuel cells because of their brittleness that could have caused damage in the plates and poor contacts.展开更多
基金This research was supported by the Sichuan Science and Technology Program(2023YFS0355).
文摘Stamping is a critical step in the manufacture of metallic bipolar plates.Typically,residual stress and a spring back effect appear on the bipolar plate after the stamping process,which impacts on the performance and lifetime of the proton exchange membrane fuel cell(PEMFC).The residual stress and spring back behavior which occur as a result of stamping a bipolar plate are investigated in this study.The effects of the punch radius,the die radius,the channel depth,and the clearance between the punch and the die on the residual stress and forming quality of the bipolar plate are examined.The stamping process can be divided into three stages.The high stress area and the middle section residual stress area were selected to study the formation process and to obtain the composition of the residual stress regions.Spring back was mainly related to the position of the fixed end of the sheet and the degree of plastic deformation,and the sheet thickness have increased by 2μm after spring back.Based on the results of finite element analysis,as described by the distribution of residual stress,the formation,the thickness of the middle cross section and the equivalent plastic strain,it was found that all the tool parameters affected the distribution of the residual stress.This research can provide a design reference for the manufacture of metallic bipolar plates based on the stamping process.
基金the support from the Shenzhen Science and Technology Program of China(No.JCYJ20220530161614031)National Natural Science Foundation of China(No.52471094)Shaanxi Coal Chemical Industry Technology Research Institute Co.,Ltd.
文摘In the realm of proton exchange membrane fuel cells(PEMFCs),the bipolar plates(BPs)are indispensable and serve pivotal roles in distributing reactant gases,collecting current,facilitating product water removal,and cooling the stack.Metal BPs,characterized by outstanding manufacturability,cost-effectiveness,higher power density,and mechanical strength,are emerging as viable alternatives to traditional graphite BPs.The foremost challenge for metal BPs lies in enhancing their corrosion resistance and conductivity under acidic conditions,necessitating the application of various coatings on their surfaces to ensure superior performance.This review summarizes and compares recent advancements in the research of eight distinct types of coatings for BPs in PEMFCs,including noble metal,carbide,ni-tride,and amorphous carbon(a-C)/metal compound composite coatings.The various challenges encountered in the manufacturing and fu-ture application of these coatings are also delineated.
基金fnancially supported by the National Science Found for Distinguished Young Scholars of China(No.52025014)the National Science and Technology Major Project(No.2017VII-0012–0108)+1 种基金the National Science Foundation of China(Nos.51901238 and 52101109)the Natural Science Foundation of Ningbo(Nos.202003N4350 and 202003N4025)。
文摘In view of the M_(n+1)AX_(n)(MAX)phase coatings benefting the adaptive passivation flm for good corrosion resistance and high electronic density of states for excellent electrical conductivity,here,we reported the Cr_(2)Al C MAX phase coatings with different preferred orientations by a homemade technique consisting of vacuum arc and magnetron sputtering.The dependence of surface and interface microstructural evolution upon the corrosion and electrochemical properties of deposited coating was focused.Results showed that all the Cr_(2)Al C coatings with different phase orientations greatly improved the performance of stainless steel(SS)316 L substrate.Specifcally,the lowest value of interface contact resistance(ICR)reached to 3.16 mΩcm^(2)and the lowest corrosion current density was 2×10^(-2)μA cm^(-2),which were much better than those of bare SS316L.The combined studies of electrochemical properties and theoretical calculations demonstrated that the Cr_(2)Al C coatings with preferred(103)orientation were easier to form oxide passivation flm on their surface to increase the corrosion resistance.
文摘Proton exchange membrane(PEM)fuel cells have significant potential for clean power generation,yet challenges remain in enhancing their performance,durability,and cost-effectiveness,particularly concerning metallic bipolar plates,which are pivotal for lightweight compact fuel cell stacks.Protective coatings are commonly employed to combat metallic bipolar plate corrosion and enhance water management within stacks.Conventional methods for predicting coating performance in terms of corrosion resistance involve complex physical-electrochemical modelling and extensive experimentation,with significant time and cost.In this study machine learning techniques are employed to model metallic bipolar plate coating performance,diamond-like-carbon coatings of varying thicknesses deposited on SS316L are considered,and coating performance is evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy.The obtained experimental data is split into two datasets for machine learning modelling:one predicting corrosion current density and another predicting impedance parameters.Machine learning models,including extreme gradient boosting(XGB)and artificial neural networks(ANN),are developed,and optimized to predict coating performance attributes.Data preprocessing and hyperparameter tuning are carried out to enhance model accuracy.Results show that ANN outperforms XGB in predicting corrosion current density,achieving an R2>0.98,and accurately predicting impedance parameters with an R2>0.99,indicating that the models developed are very promising for accurate prediction of the corrosion performance of coated metallic bipolar plates for PEM fuel cells.
文摘Bipolar plates perform as current conductors between cells, provide conduits for reactant gases, facilitate water and thermal management through the cells, and constitute the backbone of a fuel cell stack. Currently, commercial bipolar plates are made of graphite composite because of its relatively low interfacial contact resistance (ICR) and high corrosion resistance. However, graphite composite’s manufacturability, permeability, and durability of shock and vibration are unfavorable in comparison to metals. Therefore, metals have been considered as a replacement material for graphite composite bipolar plates. The main objective of this study is to evaluate the effect of terminal connection design and bipolar plate material on PEM fuel cell overall performance. The study has indicated that single cell performance can be improved by combining terminals into metallic bipolar plates. This terminal design reduces the internal cell resistance and eliminates the need for additional terminal plates. The improved single cell performance by 18% and the increased savings in hydrogen consumption by 15% at the current density of 0.30 A/cm2 was attributed to the robust metal to metal contact between the terminal and the metallic bipolar plates. However, connecting metal terminal directly into graphite bipolar plates did not exhibit similar improvement in the performance of graphite fuel cells because of their brittleness that could have caused damage in the plates and poor contacts.
