Performance Degradation Prediction of Proton Exchange Membrane Fuel Cell Based on CEEMDAN-KPCA and DA-GRU Networks

In order to improve the performance degradation prediction accuracy of proton exchange membrane fuel cell(PEMFC),a fusion prediction method(CKDG)based on adaptive noise complete ensemble empirical mode decomposition(CEEMDAN),kernel principal component analysis(KPCA)and dual attention mechanism gated recurrent unit neural network(DA-GRU)was proposed.CEEMDAN and KPCA were used to extract the input feature data sequence,reduce the influence of random factors,and capture essential feature components to reduce the model complexity.The DA-GRU network helps to learn the feature mapping relationship of data in long time series and predict the changing trend of performance degradation data more accurately.The actual aging experimental data verify the performance of the CKDG method.The results show that under the steady-state condition of 20%training data prediction,the CKDA method can reduce the root mean square error(RMSE)by 52.7%and 34.6%,respectively,compared with the traditional LSTM and GRU neural networks.Compared with the simple DA-GRU network,RMSE is reduced by 15%,and the degree of over-fitting is reduced,which has higher accuracy.It also shows excellent prediction performance under the dynamic condition data set and has good universality.

Effects of baffle position in serpentine flow channel on the performance of proton exchange membrane fuel cells

This study used a three-dimensional numerical model of a proton exchange membrane fuel cell with five types of channels:a smooth channel(Case 1);eight rectangular baffles were arranged in the upstream(Case 2),midstream(Case 3),downstream(Case 4),and the entire cathode flow channel(Case 5)to study the effects of baffle position on mass transport,power density,net power,etc.Moreover,the effects of back pressure and humidity on the voltage were investigated.Results showed that compared to smooth channels,the oxygen and water transport facilitation at the diffusion layer-channel interface were added 11.53%-20.60%and 7.81%-9.80%at 1.68 A·cm^(-2)by adding baffles.The closer the baffles were to upstream,the higher the total oxygen flux,but the lower the flux uniformity the worse the water removal.The oxygen flux of upstream baffles was 8.14%higher than that of downstream baffles,but oxygen flux uniformity decreased by 18.96%at 1.68 A·cm^(-2).The order of water removal and voltage improvement was Case 4>Case 5>Case 3>Case 2>Case 1.Net power of Case 4 was 9.87%higher than that of the smooth channel.To the Case 4,when the cell worked under low back pressure or high humidity,the voltage increments were higher.The potential increment for the back pressure of 0 atm was 0.9%higher than that of 2 atm(1 atm=101.325 kPa).The potential increment for the humidity of 100%was 7.89%higher than that of 50%.

Comparative review of corrosion-resistant coatings on metal bipolar plates of proton exchange membrane fuel cells

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.

Probing the Efficiency of PPMG-Based Composite Electrolytes for Applications of Proton Exchange Membrane Fuel Cell

PPMG-based composite electrolytes were fabricated via the solution method using the polyvinyl alcohol and polyvinylpyrrolidone blend reinforced with various contents of sulfonated inorganic filler.Sulfuric acid was employed as the sulfonating agent to functionalize the external surface of the inorganic filler,i.e.,graphene oxide.The proton conductivities of the newly prepared proton exchange membranes(PEMs)were increased by increasing the temperature and content of sulfonated graphene oxide(SGO),i.e.,ranging from 0.025 S/cm to 0.060 S/cm.The induction of the optimum level of SGO is determined to be an excellent route to enhance ionic conductivity.The single-cell performance test was conducted by sandwiching the newly prepared PEMs between an anode(0.2 mg/cm^(2) Pt/Ru)and a cathode(0.2 mg/cm^(2) Pt)to prepare membrane electrode assemblies,followed by hot pressing under a pressure of approximately 100 kg/cm^(2) at 60℃for 5–10 min.The highest power densities achieved with PPMG PEMs were 14.9 and 35.60 mW/cm^(2) at 25℃and 70℃,respectively,at ambient pressure with 100%relative humidity.Results showed that the newly prepared PEMs exhibit good electrochemical performance.The results indicated that the prepared composite membrane with 6 wt%filler can be used as an alternative membrane for applications of high-performance proton exchange membrane fuel cell.

Pore-Scale Investigation of Coupled Two-Phase and Reactive Transport in the Cathode Electrode of Proton Exchange Membrane Fuel Cells

A three-dimensional multicomponent multiphase lattice Boltzmann model(LBM)is established to model the coupled two-phase and reactive transport phenomena in the cathode electrode of proton exchange membrane fuel cells.The gas diff usion layer(GDL)and microporous layer(MPL)are stochastically reconstructed with the inside dynamic distribution of oxygen and liquid water resolved,and the catalyst layer is simplifi ed as a superthin layer to address the electrochemical reaction,which provides a clear description of the fl ooding eff ect on mass transport and performance.Diff erent kinds of electrodes are reconstructed to determine the optimum porosity and structure design of the GDL and MPL by comparing the transport resistance and per-formance under the fl ooding condition.The simulation results show that gradient porosity GDL helps to increase the reactive area and average concentration under fl ooding.The presence of the MPL ensures the oxygen transport space and reaction area because liquid water cannot transport through micropores.Moreover,the MPL helps in the uniform distribution of oxygen for an effi cient in-plane transport capacity.Crack and perforation structures can accelerate the water transport in the assembly.The systematic perforation design yields the best performance under fl ooding by separating the transport of liquid water and oxygen.

Multi-objective optimization of the cathode catalyst layer micro-composition of polymer electrolyte membrane fuel cells using a multi-scale,two-phase fuel cell model and data-driven surrogates

Polymer electrolyte membrane fuel cells(PEMFCs)are considered a promising alternative to internal combustion engines in the automotive sector.Their commercialization is mainly hindered due to the cost and effectiveness of using platinum(Pt)in them.The cathode catalyst layer(CL)is considered a core component in PEMFCs,and its composition often considerably affects the cell performance(V_(cell))also PEMFC fabrication and production(C_(stack))costs.In this study,a data-driven multi-objective optimization analysis is conducted to effectively evaluate the effects of various cathode CL compositions on Vcelland Cstack.Four essential cathode CL parameters,i.e.,platinum loading(L_(Pt)),weight ratio of ionomer to carbon(wt_(I/C)),weight ratio of Pt to carbon(wt_(Pt/c)),and porosity of cathode CL(ε_(cCL)),are considered as the design variables.The simulation results of a three-dimensional,multi-scale,two-phase comprehensive PEMFC model are used to train and test two famous surrogates:multi-layer perceptron(MLP)and response surface analysis(RSA).Their accuracies are verified using root mean square error and adjusted R^(2).MLP which outperforms RSA in terms of prediction capability is then linked to a multi-objective non-dominated sorting genetic algorithmⅡ.Compared to a typical PEMFC stack,the results of the optimal study show that the single-cell voltage,Vcellis improved by 28 m V for the same stack price and the stack cost evaluated through the U.S department of energy cost model is reduced by$5.86/k W for the same stack performance.

Simultaneous generation of electricity, ethylene and decomposition of nitrous oxide via protonic ceramic fuel cell membrane reactor

Ethylene,one of the most widely produced building blocks in the petrochemical industry,has received intense attention.Ethylene production,using electrochemical hydrogen pump-facilitated nonoxidative dehydrogenation of ethane(NDE)to ethylene,is an emerging and promising route,promoting the transformation of the ethylene industry from energy-intensive steam cracking process to new electrochemical membrane reactor technology.In this work,the NDE reaction is incorporated into a BaZr_(0.1)Ce_(0.7)Y_(0.1)Yb_(0.1)O_(3-δ)electrolyte-supported protonic ceramic fuel cell membrane reactor to co-generate electricity and ethylene,utilizing the Nb and Cu doped perovskite oxide Pr_(0.6)Sr_(0.4)Fe_(0.8)Nb_(0.1)Cu_(0.1)O_(3-δ)(PSFNCu)as anode catalytic layer.Due to the doping of Nb and Cu,PSFNCu was endowed with high reduction tolerance and rich oxygen vacancies,showing excellent NDE catalytic performance.The maximum power density of the assembled reactor reaches 200 mW cm^(-2)at 750℃,with high ethane conversion(44.9%)and ethylene selectivity(92.7%).Moreover,the nitrous oxide decomposition was first coupled in the protonic ceramic fuel cell membrane reactor to consume the permeated protons.As a result,the generation of electricity,ethylene and decomposition of nitrous oxide can be simultaneously obtained by a single reactor.Specifically,the maximum power density of the cell reaches 208 mW cm^(-2)at 750℃,with high ethane conversion(45.2%),ethylene selectivity(92.5%),and nitrous oxide conversion(19,0%).This multi-win technology is promising for not only the production of chemicals and energy but also greenhouse gas reduction.

Development and Challenges of Electrode Ionomers Used in the Catalyst Layer of Proton-Exchange Membrane Fuel Cells:A Review

The electrode ionomer plays a crucial role in the catalyst layer(CL) of a proton-exchange membrane fuel cell(PEMFC) and is closely associated with the proton conduction and gas transport properties,structural stability,and water management capability.In this review,we discuss the CL structural characteristics and highlight the latest advancements in ionomer material research.Additionally,we comprehensively introduce the design concepts and exceptional performances of porous electrode ionomers,elaborate on their structural properties and functions within the fuel cell CL,and investigate their effect on the CL microstructure and performance.Finally,we present a prospective evaluation of the developments in the electrode ionomer for fabricating CL,offering valuable insights for designing and synthesizing more efficient electrode ionomer materials.By addressing these facets,this review contributes to a comprehensive understanding of the role and potential of electrode ionomers for enhancing PEMFC performance.

CFD Analysis of Spiral Flow Fields in Proton Exchange Membrane Fuel Cells

Proton exchange membrane fuel cells(PEMFCs)are largely used in various applications because of their pollution-free products and high energy conversion efficiency.In order to improve the related design,in the present work a new spiral flow field with a bypass is proposed.The reaction gas enters the flow field in the central path and diffuses in two directions through the flow channel and the bypass.The bypasses are arranged incrementally.The number of bypasses and the cross-section size of the bypasses are varied parametrically while a single-cell model of the PEMFC is used.The influence of the concentration of liquid water and oxygen in the cell on the performance of different flow fields is determined by means of Computational fluid dynamics(COMSOL Multiphysics software).Results show that when the bypass number is 48 and its cross-sectional area is 0.5 mm^(2),the cell exhibits the best performances.

Ultrafine ordered L1_(2)-Pt-Co-Mn ternary intermetallic nanoparticles as high-performance oxygen-reduction electrocatalysts for practical fuel cells

The long-range periodically ordered atomic structures in intermetallic nanoparticles(INPs)can significantly enhance both the electrocatalytic activity and electrochemical stability toward the oxygen reduction reaction(ORR)compared to the disordered atomic structures in ordinary solid-solution alloy NPs.Accordingly,through a facile and scalable synthetic method,a series of carbon-supported ultrafine Pt_3Co_(x)Mn_(1-x)ternary INPs are prepared in this work,which possess the"skin-like"ultrathin Pt shells,the ordered L1_(2) atomic structure,and the high-even dispersion on supports(L1_(2)-Pt_3Co_(x)Mn_(1-x)/~SPt INPs/C).Electrochemical results present that the composition-optimized L1_(2)-Pt_3Co_(0.7)Mn_(0.3)/~SPt INPs/C exhibits the highest electrocata lytic activity among the series,which are also much better than those of the pristine ultrafine Pt/C.Besides,it also has a greatly enhanced electrochemical stability.In addition,the effects of annealing temperature and time are further investigated.More importantly,such superior ORR electrocatalytic performance of L1_(2)-Pt_3Co_(0.7)Mn_(0.3)/~SPt INPs/C are also well demonstrated in practical fuel cells.Physicochemical characterization analyses further reveal the major origins of the greatly enhanced ORR electrocata lytic performance:the Pt-Co-Mn alloy-induced geometric and ligand effects as well as the extremely high L1_(2) atomic-ordering degree.This work not only successfully develops a highly active and stable ordered ternary intermetallic ORR electrocatalyst,but also elucidates the corresponding"structure-function"relationship,which can be further applied in designing other intermetallic(electro)catalysts.

Cholesterol and Sericin as First Aid for Damaged Cells

Cells are surrounded by a double-layered phospholipid cell membrane responsible for the isolation of intracellular contents, active regulation of uptake from the extracellular environment, and intercellular connection and communication. These cell membranes must be intact and functionally active for cell survival and biological functioning. Compromised damage repair mechanisms usually result in impaired cellular homeostasis, leading to early or late problems. Chronic myopathies, certain myocardial diseases, aging, and acute or chronic neurodegenerative diseases (like Parkinson and Alzheimer) are directly related to cell membrane damage. This study examined the effect of a cholesterol-loaded nanoparticle (methyl-beta cyclodextrin) or the silk protein sericin on cell membrane and DNA integrity and cell viability in an in vitro cell damage model (frozen-thawed rabbit sperm cells). The cells were stored in liquid nitrogen (-196°C), thawed in small batches, and treated with cholesterol-loaded cyclodextrin or sericin before incubation at 35°C for 4 hours. Cell membrane integrity, DNA damage, and viability rates were assessed immediately after thawing and after the incubation period. The administration of sericin and cholesterol in a cell damage model increased cell survival and reduced DNA damage over a 4-hour post-thaw incubation period, suggesting their potential use as a “first aid” intervention at the cellular level.

Effects of BYHW Decoction and Its Effective Constituents on the Fluidity of the Cell Membrane in a Stroke-Modeled Rat Brain

With in vitro spin labeling electron spin resonance (ESR) spectroscopy, we have studied the effects of Bu Yang Huan Wu (BYHW) decoction and its effective constituents such as astragaloside IV ferulic acid, chuanxiongzine, rutin, chlorogenic acid, 9,10 dimethoxy pterocarpane 7 O β D glucoside, calycosin, formononetin, calycosin 7 O glucoside, paeoniflorin, paeonal and quercein on the cell membrane fluidity of a rat brain which was modeled after the dual cervical arteries were intercepted and released for realizing an ischemia reperfusion injury which was selected as a brain stroke model. Our results indicated that the cell membrane fluidity in the model group decreased approximately 8% compared with the control group, and after brain cells were incubatied with species, the membrane fluidity could be recovered closely to the control level depending on the BYHW decoction and its different constituents. As the membrane fluidity is a very sensitive biological index which reflectsd the cell status, our method will be useful to study the molecular mechanism of tradition Chinese medicine (TCM) and its combination recipe.

Methanol Perturbing Modeling Cell Membranes Investigated using Linear and Nonlinear Vibrational Spectroscopy

Cell membranes play a crucial role in many biological functions of cells. A small change in the composition of cell membranes can strongly influence the functions of membrane-associated proteins, such as ion and water channels, and thus mediate the chemical and physical balance in cells. Such composition change could originate from the introduction of short-chain alcohols, or other anesthetics into membranes. In this work, we have applied sum frequency generation vibrational spectroscopy （SFG-VS）, supplemented by attenuated total reflectance Fourier transform infrared spectroscopy （ATR-FTIR）, to investigate interaction between methanol and 1,2-dimyristoyl-d54-sn-glycero-3-phosphocholine （d54-DMPC） lipid bilayers. Lipid＇s hydrocarbon interior is deuterated while its head group is hydrogenated. At the same time, CH3 symmetric stretch from methanol and lipid head amine group has different frequency, thus we can distinguish the behaviors of methanol, lipid head amine group, and lipid hydrocarbon interior. Based on the spectral feature of the bending mode of the water molecules replaced by methanol, we determined that the methanol molecules are intercalated into the region between amine and phosphate groups at the lipid hydrophilic head. The dipole of CH3 groups of methanol and lipid head, and the water O-H M1 adopt the same orientation directions. The introduction of methanol into the lipid hydrophilic head group can strongly perturb the entire length of the alkyl chains, resulting that the signals of CD2 and CD3 groups from both leaflets can not cancel each other.

Coarse grained molecular dynamics and theoretical studies of carbon nanotubes entering cell membrane

Motivated by recent experimental observations that carbon nanotubes （CNT） can enter animal cells, here we conduct coarse grained molecular dynamics and theoretical studies of the intrinsic interaction mechanisms between CNT＇s and lipid bilayer. The results indicate that CNT-cell interaction is dominated by van der Waals and hydrophobic forces, and that CNT＇s with sufficiently small radii can directly pierce through cell membrane while larger tubes tend to enter cell via a wrapping mechanism. Theoretical models are proposed to explain the observed size effect in transition of entry mechanisms.

Using cell membrane chromatography and HPLC-TOF/MS method for in vivo study of active components from roots of Aconitum carmichaeli

An offline two-dimensional system combining a rat cardiac mascle cell membrane chromatography time-of-flight mass spectrometry （CMC-TOF/MS） with a high performance liquid chromatography time-of-flight mass spectrometry （HPLC-TOF/MS） was established for investigating the parent components and metabolites in rat urine samples after administration of the roots of Aconitum carmichaeli. On the basis of the analysis of the first dimension, retention components of the urine sample were collected into 30 fractions （one fraction per minute）. Then offline analysis of the second dimension was carried out. 34 compounds including 24 parent alkaloids and 10 potential metabolites were identified from the dosed rat urine, and then binding affinities of different compounds on cell membranes were compared and influences of some functional groups on activity were estimated with the semi-quantification and curve fitting method. As a result, binding affinities decreased along with the process of deacylation, debenzoylation and demethylation, which may be related to the alleviation of toxicity in the procedure of herb processing or metabolism. Moreover, some minor components in rat urine （Songorine, 14-benzoylneoline, Deoxyaconitine, etc. ） exerted relatively strong affinity on cell membranes are worth exploring. The results delivered by the system suggest that the CMC can be applied to in vivo study.

Ti/(Ti,Cr)N/CrN multilayer coated 316L stainless steel by arc ion plating as bipolar plates for proton exchange membrane fuel cells

Arc ion plating (AIP) is applied to form Ti/(Ti,Cr)N/CrN multilayer coating on the surface of 316L stainless steel (SS316L) as bipolar plates for proton exchange membrane fuel cells (PEMFCs). The characterizations of the coating are analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Interfacial contact resistance (ICR) between the coated sample and carbon paper is 4.9 m Omega cm(2) under 150 N/cm(2), which is much lower than that of the SS316L substrate. Potentiodynamic and potentiostatic tests are performed in the simulated PEMFC working conditions to investigate the corrosion behaviors of the coated sample. Superior anticorrosion performance is observed for the coated sample, whose corrosion current density is 0.12 mu A/cm(2). Surface morphology results after corrosion tests indicate that the substrate is well protected by the multilayer coating. Performances of the single cell with the multilayer coated SS316L bipolar plate are improved significantly compared with that of the cell with the uncoated SS316L bipolar plate, presenting a great potential for PEMFC application. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

Modification of biomaterials surface by mimetic cell membrane to improve biocompatibility

Modification of biomaterials surface by mimetic cell membrane for improving biocompatibility, to imitate the excellent biological and physiological proper- ties of the natural cell membrane, is an important research area in materials science. Numerous studies have been attempted to construct a mimetic cell membrane biointer- face composed of phosphorylcholine （PC）-containing polymers or other phospholipid analogues on biomaterials surface. PC-containing biointerfaces show outstanding characteristics, especially in biological aspects such as blood compatibility and antifouling property. In this mini-review, the strategies of membrane mimetic modification of biomaterials and their antifouling applications are summarized.

Screening of immune cell activators from Astragali Radix using a comprehensive two-dimensional NK-92MI cell membrane chromatography/C18 column/time-of-flight mass spectrometry system

Astragali Radix(AR)is a clinically used herbal medicine with multiple immunomodulatory activities that can strengthen the activity and cytotoxicity of natural killer(NK)cells.However,owing to the complexity of its composition,the specific active ingredients in AR that act on NK cells are not clear yet.Cell membrane chromatography(CMC)is mainly used to screen the active ingredients in a complex system of herbal medicines.In this study,a new comprehensive two-dimensional(2D)NK-92MI CMC/C18 column/time-of-flight mass spectrometry(TOFMS)system was established to screen for potential NK cell activators.To obtain a higher column efficiency,3-mercaptopropyltrimethoxysilane-modified silica was synthesized to prepare the NK-92MI CMC column.In total,nine components in AR were screened from this system,which could be washed out from the NK-92MI/CMC column after 10 min,and they showed good affinity for NK-92MI/CMC column.Two representative active compounds of AR,isoastragaloside Ⅰ and astragaloside IV,promoted the killing effect of NK cells on K562 cells in a dose-dependent manner.It can thus suggest that isoastragaloside Ⅰ and astragaloside Ⅳ are the main immunomodulatory components of AR.This comprehensive 2D NK-92MI CMC analytical system is a practical method for screening immune cell activators from other herbal medicines with immunomodulatory effects.

Process and challenges of stainless steel based bipolar plates for proton exchange membrane fuel cells

Proton exchange membrane fuel cell(PEMFC)powered automobiles have been recognized to be the ultimate solution to replace traditional fuel automobiles because of their advantages of PEMFCs such as no pollution,low temperature start-up,high energy density,and low noise.As one of the core components,the bipolar plates(BPs)play an important role in the PEMFC stack.Traditional graphite BPs and composite BPs have been criticized for their shortcomings such as low strength,high brittleness,and high processing cost.In contrast,stainless steel BPs(SSBPs)have recently attracted much attention of domestic and foreign researchers because of their excellent comprehensive performance,low cost,and diverse options for automobile applications.However,the SSBPs are prone to corrosion and passivation in the PEMFC working environment,which lead to reduced output power or premature failure.This review is aimed to summarize the corrosion and passivation mechanisms,characterizations and evaluation,and the surface modification technologies in the current SSBPs research.The non-coating and coating technical routes of SSBPs are demonstrated,such as substrate component regulation,thermal nitriding,electroplating,ion plating,chemical vapor deposition,and physical vapor deposition,etc.Alternative coating materials for SSBPs are metal coatings,metal nitride coatings,conductive polymer coatings,and polymer/carbon coatings,etc.Both the surface modification technologies can solve the corrosion resistance problem of stainless steel without affecting the contact resistance,however still facing restraints such as long-time stability,feasibility of low-cost,and mass production process.This paper is believed to enrich the knowledge of high-performance and long-life BPs applied for PEMFC automobiles.

Buyang Huanwu decoction enhances cell membrane fluidity in rats with cerebral ischemia/reperfusion

After bilateral carotid artery occlusion for 30 minutes and reperfusion for 2 hours, distinct pathological changes presented in the cerebral cortex and cerebellum of rats. Compared with normal rats, nerve cell membrane fluidity significantly decreased in ischemia/reperfusion rats as detected by spin-labeling electron spin resonance, consistent with order parameter S and rotational correlation time TC measurements. Brain nerve cells from rats with ischemia/reperfusion injury were cultured with 1-100 mg/mL Buyang Huanwu decoction. Results showed that Buyang Huanwu decoction gradually increased membrane fluidity dose-dependently to normal levels, and eliminated hydroxide （OH＇） and superoxide （O2＇） free radicals dose-dependenUy. These findings suggest that Buyang Huanwu decoction can protect against cell membrane fluidity changes in rats with ischemia/ reperfusion injury by scavenging free radicals.