To address the strong thermo-fluid-electrochemical coupling and performance trade-offs in proton exchange membrane fuel cells (PEMFCs) under high current density, this study develops a multi-objective optimization framework integrating design of experiments, entropy-weighted TOPSIS methods (EWM-TOPSIS), and machine learning. A three-dimensional asymmetric full-scale PEMFC model integrating a micro-encapsulated phase change material suspension (MePCS) as the coolant is established, and a Taguchi (L64(4 9 )) orthogonal array is employed to systematically explore nine operating parameters. The study elucidates the coupled mechanisms of heat transfer, mass transport, and parasitic power losses. Sensitivity analysis indicates that coolant temperature and phase change material volume fraction predominantly govern membrane temperature uniformity, contributing 57.58% and 21.82%, respectively. Backpressure dominates mass transport, accounting for 87.75%, while the cathode stoichiometric ratio primarily controls net power density, contributing 58.88% with a negative correlation of-0.76. By integrating an ensemble Gaussian process regression surrogate model with NSGA-II, the framework achieves a synergistic improvement in output voltage to approximately 0.69 V and net power density to about 1.49 W center dot cm-2 , with numerical deviations below 1%, effectively replacing costly simulations. Verification at 2.6 A center dot cm-2 demonstrates that optimized Case 3 outperforms Case 5 by 13.3% in net power density. The methodology provides a robust quantitative foundation and practical guidance for thermal management and comprehensive multi-objective optimization of high-power PEMFC stacks.

Skid-mounted integrated hydrogen production and refueling stations feature dense equipment, compact layout and flexible construction. Precisely due to these characteristics, a hydrogen leakage accident would lead to severe consequences for such stations. Taking a skid-mounted integrated hydrogen production and refueling station in Weifang, China, as the research object, this paper systematically conducts numerical simulation on the hydrogen leakage and dispersion behavior of hydrogen storage tanks, and carries out corresponding safety risk assessment. The results demonstrate that the compact layout is prone to causing local hydrogen accumulation, while leakage toward open areas can markedly reduce the volume and mass of flammable hydrogen clouds (FHC) and shorten their dispersion time. The open-air layout greatly increases the risk of hydrogen leakage caused by pipeline failure; as the leakage aperture increases, the hydrogen leakage rate rises and the hazardous impact scope expands. The low station structure makes ambient wind exert a significant influence on hydrogen dispersion. Upwind tends to trap hydrogen around hydrogen storage equipment, posing major potential safety hazards, whereas increased wind velocity facilitates the rapid dispersion of hydrogen.

Efficient thermal management is crucial for maintaining the durability and electrochemical stability of proton exchange membrane fuel cells (PEMFCs). A three-dimensional (3D) multiphysics model was developed to investigate the coupled heat-fluid-electrochemical behavior of PEMFCs using a micro-encapsulated phase change material suspension (MePCS) as coolant. The effects of micro-encapsulated phase change material (MePCM) volume fraction (phi v), coolant velocity (Vcoolant), and inlet temperature (Tin) on thermal and electrochemical performance were systematically analyzed. Results show that incorporating MePCS effectively enhances temperature uniformity and suppresses local overheating. Compared with pure water, the maximum membrane temperature difference (Delta Tmax) and temperature uniformity index (TUI) decreased by 68.2% and 42.3%, respectively. The optimal operating parameters were identified as phi v= 15%, Vcoolant= 0.05 m/s, and Tin = 340.15 K, achieving a net power density of 0.518 W & sdot;cm-2. Moreover, the co-flow configuration of the reaction gas and coolant improved power density by 1.41% over counter-flow, attributed to better heat-water-gas coupling. These findings demonstrate that MePCS based coolants provide an effective approach to improving PEMFCs water and thermal uniformity and overall efficiency.

Proton exchange membrane fuel cells (PEMFCs) hold broad prospects in clean energy applications, but thermal management remains a critical bottleneck restricting their industrialization. This study experimentally investigates the temperature distribution and evolution characteristics of PEMFCs under dynamic operating conditions. A customized printed circuit board (PCB) integrated with 16 negative temperature coefficient (NTC) thermistors was adopted for high-resolution temperature measurement. The results show that the serpentine flow field (SFF) exhibits superior temperature uniformity and parameter adaptability compared to the parallel flow field (PFF) due to its cross-channel heat transfer advantage. The optimal operating parameters for SFF were determined as a cathode stoichiometric ratio (xi c ) of 2.0 and a backpressure (P B ) of 100 kPa, with which SFF can adapt to all kinds of dynamic conditions. While the PFF requires dynamic parameter adjustment to balance temperature distribution. During dynamic operation, the high-temperature zone expands toward the center with increasing current density. The high-load condition shows more significant thermal accumulation and larger temperature differences than the low-load condition. This study facilitates a deeper understanding of the internal thermal distribution characteristics and evolution mechanisms under dynamic conditions. The proposed highresolution temperature measurement scheme and optimized thermal management strategies offer a valuable reference paradigm for contributing to the rational design of thermal management systems.

The explosive hydrolysis characteristics of highly reactive Al-based composites not only severely limit their application in proton exchange membrane fuel cells (PEMFCs) but also pose risks of hydrogen flash fires and dust explosions. To address this, this study introduced MgH2 into Al-based composites via mechanical ball milling to prepare Al@MgH2 co-hydrolyzed hydrogen generation materials. The hydrolysis behavior of Al@MgH2 exhibited a synergistic "inhibition-promotion" effect: (1) the initial reaction intensity of Al was significantly suppressed, reducing the maximum hydrogen generation rate (mHGR) from 250 mL center dot s- 1 (Al-based composite) to 135 mL center dot s- 1 (Al@30%MgH2); (2) the heat from Al hydrolysis conversely accelerated MgH2 hydrolysis kinetics, forming a positive synergy. Furthermore, MgH2 incorporation increased the composite's theoretical hydrogen generation from 1072 mL center dot g- 1 to 1285 mL center dot g- 1. To enable on-demand hydrogen supply, a pump-driven hydrolysis device was constructed, and the material was compressed into blocks. By controlling the MgCl2 solution flow rate (1.5-7.5 mL center dot min- 1), precise regulation of stable hydrogen generation rates between 1.4 and 8.8 mL center dot s- 1 was achieved. This system was successfully coupled directly with a PEMFC, enabling on-demand current outputs ranging from 1.9 to 2.4 A center dot cm- 2 under a constant voltage of 0.5 V via dynamic hydrogen supply. It maintained a stable current of 2.4 A center dot cm- 2 for 171 s. This research not only demonstrates the practical application potential of Al@MgH2, but also provides a universal systems engineering solution for regulating the hydrolysis behavior of highly active materials. It holds significant importance for the development of safe, instantaneous, and controllable chemical hydrogen storage and supply technologies.

Optimization of the membrane electrode assembly (MEA) is critical for enhancing hydrogen production and energy conversion efficiency in unitized regenerative fuel cells (URFCs). High-porosity bifunctional MEAs can be effectively fabricated by physically mixing Pt and IrO2catalysts and depositing them onto a proton exchange membrane. The MEAs were characterized using cyclic voltammetry and electrochemical impedance spectroscopy (EIS), with EIS data further analyzed via the distribution of relaxation times method to separate high-frequency processes that are otherwise difficult to distinguish, thereby providing a basis for establishing an equivalent circuit model for URFCs. Experimental results indicate that the round-trip efficiency (RTE) of URFCs under constant electrode configuration is highly sensitive to the composition of the anode catalyst layer. When the mixed catalyst layer contains IrO2and Pt in a 5:5 ratio, with a total catalyst loading of 2 mg/cm2 and an ionomer content of 15%, the effective electrochemical surface areas of Pt and IrO2reach their maximum values of 13.6 m2/g and 80.25 m2/g, respectively. Under this configuration, the URFC achieves a RTE of 45.94% at 1 A/cm2 during cycling between water electrolysis and fuel cell modes. Moreover, EIS comparisons reveal that the anode composition significantly influences the overall HFR and charge transfer process in FC mode, indicating that optimizing the anode composition in URFCs is a key factor for enhancing FC mode performance.

To achieve excellent performance, proton exchange membrane fuel cells typically undergo activation treatment prior to operation. Traditional constant-voltage or constant-current activation methods are time-consuming and require significant hydrogen consumption. Electrochemical hydrogen pumping can rapidly activate fuel cells by applying an external current to dissociate hydrogen at the anode and regenerate it at the cathode. This study systematically investigates the effects of activation current density, relative humidity, and time intervals on electrochemical hydrogen pumping activation through experimental and theoretical approaches. Results show that the optimal activation current density is 50 mA center dot cm 2, coinciding with the best membrane hydration under this condition and enabling an 80.7 % performance improvement at 2000 mA center dot cm 2. Meanwhile, the optimal relative humidity of 150 % indicates that appropriate supersaturated humidification could effectively reduce ohmic resistance and charge transfer resistance, thereby enhancing the performance by 86.9 % at 2000 mA center dot cm 2. The total activation duration determines the post-activation cell performance, while the interval between hydrogen pumping steps exhibits minimal impact on activation effectiveness and extending hydrogen pumping activation beyond 25 min provides limited improvement in cell performance. This study provides critical guidance for electrochemical hydrogen pumping activation of fuel cells.

The characteristics of internal heat and mass distribution are key determinants of the performance, durability, and efficiency of proton exchange membrane fuel cells (PEMFCs). Owing to the challenges of the high computational cost of traditional CFD simulations and the limited accuracy of data-driven models with large datasets for obtaining the local distribution characteristics, this study introduces a multi-dimensional prediction approach for PEMFC performance analysis by combining physical models with data-driven models. Through geometric partitioning based on rib-priority and relative standard deviation (RSD) convergence evaluation, the data volume can be significantly reduced while preserving the characteristics of the data distribution. Subsequently, a multi-dimensional prediction model is developed using neural network algorithms. The proposed method exhibits excellent performance with a mean absolute percentage error (MAPE) below 3% and a coefficient of determination (R2) exceeding 0.998 for key performance parameters prediction, such as current density, reactant concentrations, water content and temperature. Furthermore, this approach facilitates real-time monitoring and optimal control of PEMFCs through state mapping analysis, which comprehensively explores full-scale performance to guide the optimization of design and control strategies.

In this study, a modified adsorbent performance indicator (API*) is proposed based on ideal adsorbed solution theory (IAST) as a dimensionless indicator for adsorbent screening. The API* is first validated for CO2 removal from natural gas, showing good agreement with established screening metrics. The indicator is subsequently applied to hydrogen purification from steam methane reforming off-gas (H2/CO2/CH4/CO = 74.12/18.60/6.15/ 1.13 mol%) using coal-derived activated carbon (CAC), KOH-activated CAC (KACa) and KOH-impregnated CAC (KACi). Dynamic breakthrough behavior is further analyzed using numerical simulations that combine IASTbased equilibrium calculations with breakthrough modeling at 3 LPM, 298.15 K and 8.5 bar. The results indicate that KACi exhibits the highest API* values and the longest impurity breakthrough times (e.g., CO2 breakthrough at 1597 s, compared with 1517 s for CAC and 1412 s for KACa), demonstrating superior dynamic performance. Overall, the proposed API* provides a preliminary screening tool for a wide range of candidate adsorbents.

A unitized regenerative fuel cell (URFC) integrates electrolytic cell (EC) and fuel cell (FC) function, enabling unified energy storage and conversion. However, performance, durability, and precious metal cost constrain each other and hinder system-level efficiency gains and scale-up. Focusing on dual functional catalysts, a multiscale mechanistic framework based on an agglomerate model is established. At the microscale, agglomerate parameters governing reaction diffusion and oxygen transport resistances are quantified. At the macroscale, porous-media transport is coupled to achieve end to end modeling and parameter unification from the catalyst layer to the channel. In the FC mode, the rate limiting mechanism shifts from kinetics to local oxygen transport as current density increases. This yields a performance gain of approximately 42.9% relative to the comparison solution. In the EC mode, the mid-to-high current region remains kinetics-dominated. Increasing Ir content elevates the reaction exchange current density, thereby lowering the kinetic overpotential for oxygen evolution reaction. To balance performance, durability, and cost, a unified metric is adopted. The optimization results of the bifunctional catalyst are mainly rich in Pt. Compared with the comparison solution, the balanced and optimal solutions deliver superior performance and durability while reducing precious group metal cost by about 43.94%. This framework provides quantitative guidance and practical cues for the design of URFC bifunctional catalysts and the optimization of precious metal utilization.

As a critical porous component of proton exchange membrane fuel cells (PEMFCs), the gas diffusion layer (GDL) plays an essential role in electron conduction, heat dissipation, and liquid-water transport. To quantitatively evaluate how microstructural features influence these transport behaviors, a three-dimensional stochastic reconstruction model with controllable porosity and fiber diameter was developed based on statistical fiber-orientation distributions. Effective through-plane electrical conductivity, thermal conductivity, and intrinsic permeability were subsequently calculated on a unified geometric basis, with both dry (gas-solid) and wet (liquid-solid) conditions considered. It is found that the relative electrical conductivity decreases by approximately 96% as porosity increases from 0.5 to 0.85, while the thermal conductivity shows an even greater reduction of about 97%. In contrast, permeability exhibits a strong nonlinear increase, rising by more than one order of magnitude across the same porosity range. Under fixed porosity, the influence of fiber diameter remains comparatively minor, altering electrical and thermal conductivities by less than 23% and affecting permeability far less than the changes driven by porosity. Dry-wet comparisons show that liquid water produces a negligible change (<0.2%) in electrical conductivity but dramatically enhances thermal conductivity by over 500%. This work provides a unified and directly comparable electro-thermal-hydraulic assessment framework, offering quantitative guidance for multi-objective GDL design and multiphysics optimization in PEMFCs.

The mass transfer mechanism in proton exchange membrane fuel cell (PEMFC) gas diffusion layer (GDL) under clamping force remains insufficiently understood. In this study, stochastic reconstruction algorithm is employed to generate the GDL microstructure, and finite element method (FEM) is conducted to analyze compressioninduced deformation. By integrating pore-scale characterization with Volume of Fluid (VOF)-based two-phase flow simulations, this work establishes a coupled "structure-mechanics-transport" framework to evaluate how key structural parameters regulate mechanical response and liquid water transport. Results indicate that porosity exerts the most pronounced effect on the stress-strain response. Furthermore, compression primarily alters the interface contact between the bipolar plate and GDL. The compression ratio shows a nonlinear relationship with porosity and pore size changes, compression ratio at 30 % sharply reduces porosity and pore size but improves pore size uniformity. and water saturation drops by 10 %-30 %, with larger saturation growth rate. The compressed layered structure reduces through plane (TP)-direction distance, while larger in plane (IP)-direction pores make liquid water prefer TP-direction transport. Compression increases TP-direction pressure difference, raising liquid water flow velocity from about 0.3 m/s to 0.5 m/s, and IP-direction pressure distribution becomes more uniform. Thinner GDL and faster flow jointly shorten liquid water breakthrough time. It aims to clarify correlations among GDL structural parameters, compression mechanics, and two-phase flow, providing theoretical support for PEMFC performance optimization.

Effective water and gas management enhances proton exchange membrane fuel cell (PEMFC) performance, with interfacial studies of membrane electrode assembly (MEA) being paramount to this effort. This study employed the lattice Boltzmann method (LBM) to analyze how compression pressure and MEA interface structure influence liquid water and oxygen transport within PEMFCs. Results demonstrate that lateral liquid water diffusion occurs throughout all MEA layers. At the catalyst coated membrane (CCM) - microporous layer (MPL) interface, pore compression limits water penetration into MPL cracks through lateral diffusion. The accumulation of interfacial water is governed by the number and morphology of MPL cracks: pressure cracks exhibit poorer water collection capability than dry cracks, whereas combined cracks improve water connectivity inside the MPL. However, lateral diffusion within MPL cracks also relieves pressure, thereby impeding water breakthrough toward the gas diffusion layer (GDL) At the MPL-GDL interface, lateral diffusion is controlled by the transition layer's contact angle and porosity-higher hydrophobicity and lower porosity suppress lateral water movement. Furthermore, oxygen transport to the catalyst layer is affected by lateral water diffusion, saturation distribution across layers, and interface geometry, while the amount of water expelled into flow channels governs the extent of CCM flooding. The established structure-performance correlation not only advances our understanding of interface design but also provides a foundation for its optimization through deep learning. The fundamental insights gained will directly inform the design of MEA, specifically to mitigate mass transport losses at high current density in PEMFC.

Proton exchange membrane fuel cells (PEMFC) experienced performance degradation under gas starvation conditions, which severely affected the uniformity of current density distribution and operational stability. This work experimentally investigated the current density distribution under different gas supply conditions with printed circuit board (PCB) segmented current technology. An extensive matrix of 21 experimental cases was designed, systematically varying the backpressure (0, 50, 100 kPa), operating temperature (60, 70, 80 degrees C), and relative humidity (60%, 80%, 100%) under both normal and gas starvation modes. It comprehensively analyzed the impact of various parameters on the transient behavior of PEMFCs during dynamic loading. To evaluate the homogeneity of the local current density distribution, a homogeneity parameter was introduced. The Pearson correlation coefficient (PCC) was then used to evaluate the correlations among various complex parameters within the PEMFC. The results indicated that a specific backpressure could effectively mitigate gas starvation issues and improve distribution homogeneity. Under anode starvation conditions, uniformity improved by 61.67% compared to 0 kPa at 100 kPa. Additionally, 70 degrees C was identified as the optimal operating temperature, resulting in a 4.39% enhancement in uniformity compared to 60 degrees C. PCC analysis reveals a strong correlation between backpressure and the homogeneity of local current density distribution under anode starvation, while temperature exhibits a significantly weaker correlation, particularly at high loads.

Understanding the multi-physics transport behavior of gas diffusion layers (GDLs) under clamping force is essential for improving the performance and durability of proton exchange membrane fuel cells (PEMFCs). In this study, a comprehensive pore-scale framework is developed to quantify the coupled effects of mechanical compression on GDL microstructure and transport properties. A stochastic numerical reconstruction algorithm is employed to generate GDL microstructure, followed by finite element method to capture compression-induced structural evolution. Pore-scale characterization reveals significant reductions in pore size with increasing compression. Based on the deformed structures, transport property demonstrate that compression enhances solid-phase transport property while substantially increasing flow resistance. A volume of fluid (VOF) model is further established to simulate non-isothermal two-phase flow within the realistic pore geometry. The results show that compression shifts the liquid-water invasion mode from channel-dominated breakthrough to a tortuous, diffusion-controlled pathway, leading to earlier breakthrough, reduced saturation, and more efficient drainage. Temperature coupling has limited influence on water distribution but noticeably affects thermal homogenization and drainage patterns. Overall, this work provides a pore-scale understanding of how clamping force regulates multi-physics transport in GDLs. The findings offer mechanistic insights for GDL structural optimization to enhance PEMFC performance and reliability.

Endowed with merits including fast response speed, high energy conversion efficiency and zero emissions, the proton exchange membrane water electrolyzer (PEMWE) is recognized as a technology with immense potential in the renewable energy domain. It is worth emphasizing that the polarization performance and mass transfer characteristics of PEMWE are crucially affected by the flow field design of its bipolar plates. This study mainly focuses on the improvement of PEMWE performance by metal foam flow field (MFFF). Metal foam structures with three different arrangements were designed and compared with the traditional flow field. The performance and water gas transport characteristics of PEMWE with different pore structure flow fields were analyzed. The results show that both the anode and cathode have a double-layer gradient pore structure, and the MFFF with descending pore size towards the PTL direction has the best performance. At a current density of 3.1A/cm2, compared with the parallel flow field, the voltage dropped by 55.6 mV, with a decrease rate of 2.4%. Compared with the serpentine flow field, the voltage dropped by 74.1 mV, with a drop rate of 3.2%. In addition, MFFF with increased pore size in outlet area exhibits superior overall performance, although the performance has not been further improved compared with the former, the pressure drop has been reduced by 50%, demonstrating better gas discharge performance. The results of this study provide valuable theoretical guidance for enhancing the performance of PEMWE.

In the proton exchange membrane water electrolyzer (PEMWE), a porous transport layer (PTL) regulates the oxygen transport path and rate at the anode of PEMWE, significantly affecting the efficiency and durability of electrolysis. In this study, a three-dimensional numerical model is constructed, coupling its simulation results as boundary conditions with a two-dimensional Lattice Boltzmann model (LBM) to account for the differences in performance and oxygen transport caused by the gradient PTL. The results suggest that the PTL with cis-gradient porosity leads to a performance enhancement of 44.6mv than the trans-gradient porosity PTL at 1.9 A/cm2 by minimizing oxygen accumulation near the catalyst layer and establishing more uniform pressure and diffusion pathways. The optimized structure increases oxygen saturation at the PTL-channel interface by 23.7% and decreases it at the CL-PTL interface by 9.7%, significantly enhancing the mass transfer and operational stability. These insights provide a foundational guideline for designing high-efficiency, durable PTL architectures and advancing next-generation PEMWE technology.