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The construction of hydrogenation infrastructure is important to promote the large-scale development of hydrogen energy industry. The technical performance of hydrogen refueling station (HRS) largely determines the refueling efficiency and cost of hydrogen fuel cell vehicles. This paper systematically lists the hydrogen refueling process and the key equipment applicable in the HRS. It comprehensively reviews the key equipment configuration from the hydrogen supply, compression, storage and refueling of the HRS. On the basis of the parameter selection and quantity configuration method, the process optimization technology related to the equipment utilization efficiency and construction cost was quantitatively evaluated. Besides, the existing problems and prospects are put forward, which lays the foundation for further research on the technical economy of HRSs.

Since agglomerates in catalyst inks affect the catalyst layers (CL) and membrane electrode assemblies (MEA) of proton exchange membrane fuel cell (PEMFC), it is important to study the connection among catalyst agglomerates, CL structure, and MEA performance. This study investigates the effect of Pt/GC catalyst agglomerates on the morphology and permeability of the CL by modulating the properties of the catalyst ink in two different ways. Additionally, MEA was further electrochemically tested to understand the relationship between the catalyst agglomerates and MEA performance. The result shows that High-pressure homogenization is more effective than mechanical shear mixing in dispersing the agglomerates in catalyst inks. However, the excessive homogenization pressure produced larger agglomerated particles, probably because more effective dispersion caused by higher homogenization pressure supplies new chain carriers for polymerization and higher temperature caused by higher homogenization pressure. Moreover, the surface of the CL fabricated in inks prepared by a homogenizer is more uniform, neat, and hydrophilic. But the number of secondary pores in the catalyst layer decreases at excessive homogeneous pressure, and the water permeability becomes poor, which in turn result in lower performance and higher mass transfer resistance. The electrochemical performance test results showed that the MEA with a relatively hydrophobic CL had a performance of 0.707 V at 1000 mA cm−2, which was 30 mV higher than that with a relatively hydrophilic CL. This study provides insights for better tuning the properties of catalyst ink, CL morphology, and permeability to obtain better performance of MEA.

The ionomer state in the catalyst ink of a proton exchange membrane fuel cell (PEMFC) plays a critical role in the formation of the catalyst/ionomer interface on the catalyst layer (CL). In this study, the effect of ionomer dispersion state on catalyst ink dispersion and the construction of a reasonable CL was investigated. The study of catalyst inks revealed that the dispersion of n-propanol (NPA) -ionomer dispersion or sonication could effectively reduce the catalyst particle size in inks. For shear-dispersion and homogenizer-dispersion inks, the catalyst particle size was reduced from 6.17 nm to 5.12 nm and from 5.12 nm to 4.67 nm, respectively. The ionomer dispersion was capable of significantly reducing the size of agglomerates in the ink, which resulted in a reduction in the particle size of agglomerates on the surface of the cathode CL and an improvement in its flatness. The pore size distributions of the MEA cathode catalyst layers showed that water bath ultrasonic treatment of the ionomer could result in a more reasonable pore structure for the catalyst layer. The single-cell test revealed that changing the ionomer's dispersion state could significantly increase the fuel cell's output voltage to 0.707 V at 1000 mA cm−2, and the cell's power density to 1028 mW cm−2 at 2000 mA cm−2.

Distribution uniformity is critical to achieve high performance for proton exchange membrane fuel cell (PEMFC) stacks. In this work, air flow distribution of a 30 kW “U-type” stack of 100 unit cells is investigated by computational fluid dynamics (CFD) simulation, Burgers vortex model is introduced to describe the mechanism of flow maldistribution. Three cases are presented to evaluate the effects of vortexes on the distribution uniformity under various average current densities, and obtain optimized design for better uniformity. The results show that the vortexes usually generate in the feed header, the flow vortex structures are governed by the feed header’s configuration. The distribution uniformity reduces dramatically with the increase of current density and the generation of vortexes. The cells that locate in the positions of vortexes get less flow allocation than other cells, distribution uniformity can improve by optimizing the feed header’s configuration to change the vortex structure of flow field.

The solid-state lithium battery (SSLB) is recognized as the most promising candidate for energy storage devices with good safety and high energy density. The solid-state electrolyte (SSE), as the most critical component of solid-state lithium batteries (SSLBs), largely leads the future battery development. To obtain the SSE with good overall performance is a significant prerequisite to realize the application of SSLBs. Garnet Li7La3Zr2O12 (LLZO) family solid-state electrolytes (SSEs) have great potential for SSLBs, owing to high ionic conductivity, wide electrochemical stability window and excellent stability against lithium metal. Achieving cubic modified LLZO of high quality is always an extremely important task in LLZO engineering. Numerous works on LLZO family SSEs and their extensions have been tried, and plenty of breakthrough results are achieved. However, these electrolytes and their SSLBs still suffer from quite a few pivotal problems for a real business. Herein, this review presents a systematic, special summary and discussion on modified LLZO, LLZO-polymer composite electrolyte and their SSLBs to better understand the progress and challenges. Notably, (i) effects of element doping, preparation techniques and storage stability of modified LLZO, (ii) fabrication, properties and lithium-ion conduction mechanism of LLZO-polymer composite electrolytes, and (iii) the direct LLZO ceramic and LLZO-polymer composite derived SSLBs are emphatically concentrated. Additionally, the instructive prospects on LLZO ceramic SSEs and LLZO-polymer composite electrolytes for SSLBs are proposed as well. We suggest that this review could enable readers to deepen their understanding of this field.

Proton exchange membrane fuel cell (PEMFC) is considered to be a promising, clean, and efficient energy conversion device. At present, the main challenges faced by the application of PEMFC in the automotive are cost and durability. Hydrogen from anode to the cathode through polymer electrolyte membrane (i.e. crossover hydrogen) affects the durability of fuel cells. In this paper, the existing literature on hydrogen crossover is reviewed and summarized from consequences, causes, mitigation measures, and detection methods. The influences of hydrogen crossover on the components and performance are discussed. The causes are analyzed from structural permeation and membrane degradation. The methods of alleviating the degradation of the membrane are summarized. The electrochemical and non-electrochemical monitoring methods are described, and the segmented current method is explained separately. The existing problems and research prospects are put forward, which lays a foundation for further research on hydrogen crossover and improvement fuel cell durability.

During the operation of proton exchange membrane fuel cell, the functional groups in the ionomer are sensitive to free radicals, then lead to membrane degradation and cell failure. A common and effective approach is employing the radical scavengers-based material, which can reduce the content of reactive radical species followed by the improvement of proton exchange membrane and catalyst layer stability. However, few literatures pay attention to the effect of spatial on the initial electrochemical performance and chemical stability of fuel cells. Herein, Zr-doped ceria particles are synthesized and used as an additive on the cathode, anode or bilayer catalyst layers of the membrane electrode assembly. The results indicate that the addition of Zr-doped ceria particles to the cathode side will slightly increase the charge transfer and mass transfer resistance, then the initial polarization performance of membrane electrode assembly is reduced. But it can greatly improve the chemical stability of membrane electrode assembly (from 72 to 204 h during open circuit voltage test).

The microporous layer (MPL) of diffusion medium has an important impact on the water management ability of proton exchange membrane fuel cells. In this study, six kinds of carbon black were used to prepare the cathode MPL. The thickness, conductivity, pore structure, hydrophobicity, and surface microstructure of MPL were characterized. The single cell was prepared and electrochemical tests were performed. The results showed that the single cell prepared by Acetylene black (ACET) and Vulcan XC-72R has a considerable power generation performance. In addition, polyvinylidene fluoride hexafluoropropylene copolymer P(VDF-HFP) was used to replace Polytetrafluoroethylene (PTFE) as hydrophobic binder. MPL with different P(VDF-HFP) contents were prepared, and the single cell performance was investigated. The results showed that all the single cells prepared by P(VDF-HFP) were worse than that of PTFE. This study provides an important reference for further improving the performance of fuel cells from the perspective of material optimization with MPL.

Proton exchange membrane fuel cells (PEMFCs) have become the most attractive power supply units for stationary and mobile applications. The operation, design characteristics, as well as performance of PEMFCs, are closely related to the multiphase transport of mass, heat, and electricity in the cell, a critical of which is the gas diffusion layer (GDL). It is very important to guarantee the transmission of water and gasses under high current density, and which is the weakness of PEMFCs at present. Microporous layer (MPL) is considered to be the key variable for mass transfer, so varieties of works focus on modification of MPL materials and its structure design. However, there is still a lack of special review to summarize and prospect the progress of MPL in recent years. This review article therefore focuses on the insights and comprehensive understanding of four critical issues of the MPL, the porosity, pore size distribution, wettability, structural design and the durability of MPL. At last, the conclusion and recommendations section summarized the future prospects and recommendations for possible research opportunities.

The durability of sealing material is one of the major challenges to the overall lifetime of proton exchange membrane fuel cell (PEMFC). In order to study the failure mode and aging mechanism of fuel cell seals, this paper focuses on the most widely used commercial silicone rubber, and an ex-situ accelerated aging method was employed by simulating the circumstance of PEMFC, including higher temperature and clamping force, lower pH value and F− with higher concentration. The main factors that affect the performance of the seal were obtained through the test of their morphologies and mechanical properties. The failure mode of the aging mechanism of the rubbers were analyzed through scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), attenuated-total-reflection infrared spectroscopy (ATR-IR), mass loss, compression set (CS), etc. It was found that temperature played an important role in the deterioration of seal performance, and the change of the parameters of the compression set with time conformed the dynamic empirical formula, which provides the experimental basis for the lifetime prediction of the seals.

Pt-rare earth catalysts are highly efficient novel electrocatalyst for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs) due to their high stability and activity. In this study, we prepare Pt-YOx/C catalysts using the traditional wet chemical reduction method. The optimal quantity of Y-oxides loaded onto the Pt/C surface is determined based on electrochemical performance using linear sweep voltammetry (LSV) and cyclic voltammetry (CV) methods. After accelerated durability tests (ADT), the remnant electrochemical surface area (ECSA) and mass active (MA) in Pt-YOx/C catalyst are relatively higher compared to the commercial Pt/C (JM). In the single-cell test, the maximum mass power densities of the MEAs prepared by self-made Pt-YOx/C and Pt/C (JM) catalysts in cathodes record at 1895 and 1371 mW mgPt−1, respectively, which shows a successful increment in platinum utilization. These results indicate that Pt-YOx/C catalyst can potentially improve the durability and lower the cost of PEMFCs.

As the liner material of type IV hydrogen storage tank, polymer is restricted in commercial application due to its high hydrogen permeability. In this paper, for the first time, the suitability of polyamide 6 (PA6) filled with lamellar inorganic components (LIC) as the hydrogen storage tank liner is comprehensively investigated, including thermal and mechanical properties, morphology and structure, rheology, and the hydrogen permeability under various temperature (−10 °C, 25 °C, 85 °C) and pressure (25 MPa, 35 MPa, 50 MPa) conditions. The results show that comparing with PA6, the thermal and processing properties of LIC/PA6 have been improved, the tensile strength, bending strength and bending modulus of LIC/PA6 are increased by 36%, 17% and 12%, respectively. Especially, the hydrogen permeability of LIC/PA6 is decreased by 3–5 times which meets the requirements specified by the hydrogen tank standard. The research work provides a theoretical basis and reference for the preparation and selection of high barrier liner materials in the future.

In order to obtain a fuel cell with both enhanced power generation performance and cell reversal resistance, the composite catalyst consisting of the self-made PtNi/C octahedral and the oxygen evolution reaction (OER) catalyst IrO2 and RuO2 is mixed and applied in the anode, and the only octahedral catalyst is employed as the cathode to prepare the membrane electrode assembly (MEA). The electrochemical activity of the composite catalyst decreases slightly, but its performance retention after the accelerated durability test (ADT) is higher. In the single cell test, the MEA fabricated using the composite catalyst maintains good single cell power generation performance. Compared with the control fabricated with Pt/C (JM), the cell voltage at 1 A cm−2 and the maximum power density are increased by 23 mV and 119 mW cm−2, respectively. Especially, its durability under continuous cell reversal condition is also improved significantly, and the holding time is prolonged by 1 h. This work realizes the transformation of the octahedral catalyst from the laboratory research to the actual application, and solves the difficulties in fuel cell application, and promotes its commercialization.

Lithium ion capacitors (LICs) with a 3–5 times higher energy density than traditional electrochemical double-layer capacitors (EDLCs), are thus considered as next generation of capacitive energy storage systems (cESSs). However, the introduction of a battery-type anode into hybrid configuration inevitably leads to scarified power density and cycling life in comparison with EDLCs, due to the imbalanced electrochemical performance of two electrodes resulted from distinct energy storage mechanisms, which means achieving competitive power density and cycling life simultaneously is an extreme challenge involving in the whole system. In this context, we rationally design an ultra-fast and ultra-stable all-graphene LIC, for which various graphene electrode constructions are synthesized orienting in the distinct energy storage principles of two electrodes, and a novel match approach derived from quasi-in-operando EIS technologies for two electrodes is proposed and applied. These systemic optimizations enable an ultra-fast and ultra-stable electrochemical performance of all-graphene LIC, which delivers an ultra-high-power density of 53,550 W kg−1 and an unprecedented cycling stability of 98.9% retention after 50,000 cycles. These results are promising in terms of pushing next generation of cESSs by combining considerable electrode constructions and match approaches.