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.

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.

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.

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.

In situ grown nanoscale platinum on carbon powder as catalyst layer in proton exchange membrane fuel cells(PEMFCs)

An extensive study has been conducted on the proton exchange membrane fuel cells （PEMFCs） with reducing Pt loading. This is commonly achieved by developing methods to increase the utilization of the platinum in the catalyst layer of the electrodes. In this paper, a novel process of the catalyst layers was introduced and investigated. A mixture of carbon powder and Nafion solution was sprayed on the glassy carbon electrode （GCE） to form a thin carbon layer. Then Pt particles were deposited on the surface by reducing hexachloroplatinic （IV） acid hexahydrate with methanoic acid. SEM images showed a continuous Pt gradient profile among the thickness direction of the catalytic layer by the novel method. The Pt nanowires grown are in the size of 3 nm （diameter） x l0 nm （length） by high solution TEM image. The novel catalyst layer was characterized by cyclic voltammetry （CV） and scanning electron microscope （SEM） as compared with commercial Pt/C black and Pt catalyst layer obtained from sputtering. The results showed that the platinum nanoparticles deposited on the carbon powder were highly utilized as they directly faced the gas diffusion layer and offered easy access to reactants （oxygen or hydrogen）.

Particle Swarm Optimization based predictive control of Proton Exchange Membrane Fuel Cell (PEMFC)

Proton Exchange Membrane Fuel Cells (PEMFCs) are the main focus of their current development as power sources because they are capable of higher power density and faster start-up than other fuel cells. The humidification system and output performance of PEMFC stack are briefly analyzed. Predictive control of PEMFC based on Support Vector Regression Machine (SVRM) is presented and the SVRM is constructed. The processing plant is modelled on SVRM and the predictive control law is obtained by using Particle Swarm Optimization (PSO). The simulation and the results showed that the SVRM and the PSO re-ceding optimization applied to the PEMFC predictive control yielded good performance.

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.

Pt/WO_3/C nanocomposite with parallel WO_3 nanorods as cathode catalyst for proton exchange membrane fuel cells

Pt/WO3/C nanocomposites with parallel WO3 nanorods were synthesized and applied as the cathode catalyst for proton exchange membrane fuel cells （PEMFCs）. Electrochemical results and single cell tests show that an enhanced activity for the oxygen reduction reaction （ORR） is obtained for the Pt/WO3/C catalyst compared with Pt/C. The higher catalytic activity might be ascribed to the improved Pt dispersion with smaller particle sizes. The Pt/WO3/C catalyst also exhibits a good electrochemical stability under potential cycling. Thus, the Pt/WO3/C catalyst can be used as a potential PEMFC cathode catalyst.

Graphite-polypyrrole coated 316L stainless steel as bipolar plates for proton exchange membrane fuel cells

316L stainless steel（SS 316L） is quite attractive as bipolar plates in proton exchange membrane fuel cells（PEMFC）.In this study,graphite-polypyrrole was coated on SS 316L by the method of cyclic voltammetry.The surface morphology and chemical composition of the graphite-polypyrrole composite coating were investigated by scanning electron microscopy（SEM） and X-ray photoelectron spectroscopy（XPS）.A simulated working environment of PEMFC was applied for testing the corrosion properties of graphite-polypyrrole coated SS 316L.The current densities in the simulated PEMFC anode and cathode conditions are around 3×10-9 and 9×10-5 A·cm-2,respectively.In addition,the interfacial contact resistance（ICR） was also investigated.The ICR value of graphite-polypyrrole coated SS 316L is much lower than that of bare SS 316L.Therefore,graphite-polypyrrole coated SS 316L indicates a great potential for the application in PEMFC.

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.

Sulfonated polybenzimidazole/amine functionalized titanium dioxide(s PBI/AFT) composite electrolyte membranes for high temperature proton exchange membrane fuel cells usage

The novel sulfonated polybenzimidazole(sPBI)/amine functionalized titanium dioxide(AFT) composite membrane is devised and studied for its capability of the application of high temperature proton exchange membrane fuel cells(HT-PEMFCs),unlike the prior low temperature AFT endeavors.The high temperature compatibility was actualized because of the filling of free volumes in the rigid aromatic matrix of the composite with AFT nanoparticles which inhibited segmental motions of the chains and improved its thermal stability.Besides,amine functionalization of TiO2 enhanced their dispersion character in the sPBI matrix and shortened the interparticle separation gap which finally improved the proton transfer after establishing interconnected pathways and breeding more phosphoric acid(PA) doping.In addition,the appeared assembled clusters of AFT flourished a superior mechanical stability.Thus,the optimized sPBI/AFT(10 wt%) showed 65.3 MPa tensile strength;0.084 S·cm^-1 proton conductivity(at 160℃;in anhydrous conditions),28.6% water uptake and PA doping level of 23 mol per sPBI repeat unit.The maximum power density peak for sPBI/AFT-10 met the figure of0.42 W·cm^-2 at 160℃(in dry conditions) under atmospheric pressure with 1.5 and 2.5 stoichiometric flow rates of H2/air.These results affirmed the probable fitting of sPBI/AFT composite for HT-PEMFC applications.

Gel-state polybenzimidazole proton exchange membranes with flexible alkyl sulfonic acid side chains for a wider operating temperature range(25–240 ℃)

High-temperature proton exchange membrane fuel cells(HT-PEMFC) possess distinct technical advantages of high output power, simplified water/heat management, increased tolerance to fuel impurities and diverse fuel sources, within the temperature range of 120–200 ℃. However, for practical automobile applications, it was crucial to broaden their low-temperature operating window and enable cold start-up capability. Herein, gel-state phosphoric acid(PA) doped sulfonated polybenzimidazole(PBI) proton exchange membranes(PEMs) were designed and synthesized via PPA sol-gel process and in-situ sultone ring-opening reactions with various proton transport pathways based on absorbed PA, flexible alkyl chain connected sulfonic acid groups and imidazole sites. The effects of flexible alkyl sulfonic acid side chain length and content on PA doping level, proton conductivity, and membrane stability under different temperature and relative humidity(RH) were thoroughly investigated. The prepared gel-state membranes contained a self-assembled lamellar and porous structure that facilitated the absorption of a large amount of PA with rapid proton transporting mechanisms. At room temperature, the optimized membrane exhibited a proton conductivity of 0.069 S cm^(-1), which was further increased to 0.162 and 0.358 S cm^(-1)at 80 and 200 ℃, respectively, without additional humidification. The most significant contribution of this work was demonstrating the feasibility of gel-state sulfonated PBI membranes in expanding HT-PEMFC application opportunities over a wider operating range of 25 to 240 ℃.

Adaptive inverse control of air supply flow for proton exchange membrane fuel cell systems

To prevent the oxygen starvation and improve the system output performance, an adaptive inverse control （AIC） strategy is developed to regulate the air supply flow of a proton exchange membrane fuel cell （PEMFC） system in this paper. The PEMFC stack and the air supply system including a compressor and a supply manifold are modeled for the purpose of performance analysis and controller design. A recurrent fuzzy neural network （RFNN） is utilized to identify the inverse model of the controlled system and generates a suitable control input during the abrupt step change of external disturbances. Compared with the PI controller, numerical simulations are performed to validate the effectiveness and advantages of the proposed AIC strategy.

Water Distribution and Removal along the Flow Channel in Proton Exchange Membrane Fuel Cells

Distribution expressions of total gas pressure and partial water vapor pressure along the channel direction were established based on lumped model by analyzing pressure loss in the channel and gas diffusion in the layer. The mechanism of droplet formation in the flow channel was also analyzed. Effects of the relative humidity, working temperature and stoichiometry on liquid water formation were discussed in detail. Moreover, the force equilibrium equation of the droplet in the flow channel was deduced, and the critical flow velocity for the water droplet removal was also addressed. The experimental results show that the threshold position of the liquid droplet is far from the inlet with the increase of temperature, and it decreases with the increase of the inlet total pressure. The critical flow velocity decreases with the increase of the radius and the working pressure.

Experimental Study on Characteristics of Cathode Fan Systems of Proton Exchange Membrane Fuel Cells

对自制的阴极开放式自增湿型质子交换膜燃料电池阴极风扇系统不同工作模式下电池的空气流量分布及温度分布开展了实验研究。采用testo435多功能测量仪测量不同工作模式下电池阴极的空气流速；采用FLUKETi25红外温度成像仪测量不同操作模式下电池的表面温度分布。实验结果表明：阴极风扇系统不同的工作模式（“吸”和“吹”）会造成空气流量分布及温度分布不同。风扇工作在“吸．”模式下，燃料电池的表面工作温度分布和空气流量分布更均匀，性能更好；电池表面工作温度分布与流过电池阴极的空气流量具有一致性。该研究对于阴极开放式燃料电池性能研究及寻求电池系统效率、性能、温湿度等整体最优具有一定的指导和参考价值。

Recent advances in phosphoric acid-based membranes for high-temperature proton exchange membrane fuel cells

High-temperature proton exchange membrane fuel cells(HT-PEMFCs)are pursued worldwide as efficient energy conversion devices.Great efforts have been made in the area of designing and developing phosphoric acid(PA)-based proton exchange membrane(PEM)of HT-PEMFCs.This review focuses on recent advances in the limitations of acid-based PEM(acid leaching,oxidative degradation,and mechanical degradation)and the approaches mitigating the membrane degradation.Preparing multilayer or polymers with continuous network,adding hygroscopic inorganic materials,and introducing PA doping sites or covalent interactions with PA can effectively reduce acid leaching.Membrane oxidative degradation can be alleviated by synthesizing crosslinked or branched polymers,and introducing antioxidative groups or highly oxidative stable materials.Crosslinking to get a compact structure,blending with stable polymers and inorganic materials,preparing polymer with high molecular weight,and fabricating the polymer with PA doping sites away from backbones,are recommended to improve the membrane mechanical strength.Also,by comparing the running hours and decay rate,three current approaches,1.crosslinking via thermally curing or polymeric crosslinker,2.incorporating hygroscopic inorganic materials,3.increasing membrane layers or introducing strong basic groups and electron-withdrawing groups,have been concluded to be promising approaches to improve the durability of HT-PEMFCs.The overall aim of this review is to explore the existing degradation challenges and opportunities to serve as a solid basis for the deployment in the fuel cell market.

Dynamic Thermal Model and Temperature Control of Proton Exchange Membrane Fuel Cell Stack

A dynamic thermal transfer model of a proton exchange membrane fuel cell (PEMFC) stack is developed based on energy conservation in order to reach better temperature control of PEMFC stack. Considering its uncertain parameters and disturbance, we propose a robust adaptive controller based on backstepping algorithm of Lyaponov function. Numerical simulations indicate the validity of the proposed controller.

Synthesis of Nafion^(■)-stabilized Pt nanoparticles to improve the durability of proton exchange membrane fuel cell

Nafion-stabilized Pt nanoparticle colloidal solution is synthesized through ethylene glycol reduction.Pt/Nafion added with carbon black as electric conduction material（labeled Pt/Nafion-XC72） shows excellent electrochemical property compared with Pt/C.After a 300-cycle discharging durability test,the cell performance of membrane electrode assembly（MEA） with the Pt/Nafion-XC72 and Pt/C catalysts indicates a 29.9% and 92.2% decrease,respectively.The charge transfer resistances of Pt/Nafion-XC72 and Pt/C increase by 27.2% and 101.9%,respectively.The remaining electrochemically active surface area of Pt is about 61.7% in Pt/Nafion-XC72 and about 38.1% in Pt/C after the durability test.The particle size of Pt/C increases from about 5.1 nm to about 10.8 nm but only from 3.6 nm to 5.8 nm in the case of Pt/Nafion-XC72.These data suggest that Pt/Nafion-XC72 as a catalyst can enhance the durability of PEMFCs compared with Pt/C.