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Proton exchange membrane fuel cells have strict requirements for the CO concentration in H2-rich fuel gas. Here, from the perspective of industrial practicability, a highly dispersed Pt catalyst (2–4 nm) supported on activated carbon (AC), which was modified by electronic promoters (K+) and structural promoters (isopropanol), is studied in detail. Compared with traditional metal oxide supports, the K–Pt/AC catalysts, which benefit from the tuned charge distribution, achieve a significant reduction of CO (from 1% to <0.1 ppb) under H2-rich conditions and show potential for used in large-scale industrial hydrogen purification. Experimental results and theoretical calculations reveal that the K atom, with its lower electronegativity, contributes to the shift of surface Pt2+to a lower binding energy due to the presence of oxygen species on the AC surface. This facilitates oxygen activation and accelerates desorption of the CO2product, thereby accelerating the reaction process and enabling the deep removal of CO in a hydrogen-rich atmosphere.

[Display omitted] Nitride multilayer coating is prepared on 316L stainless steel (SS) by employing multi-arc ion planting to enhance the corrosion resistance, interfacial electrical conductivity, and hydrophobicity. The electrochemical results show that the coating can effectively inhibit the interface reactions. The i corr of the coated 316L SS was 0.04 μA cm−2, which was significantly lower than that of the substrate (54.7 μA cm−2). The protection efficiency (P i) of the multilayer nitride coating was 99.93%. After 9 hours of PP, the current density of the coated 316L SS stabilized at 0.085 μA cm−2. The typical ICR value of the coated 316L SS slightly increased from 8.6 mΩ cm2 to 12.6 mΩ cm2. The XPS results demonstrated that the significantly increased ICRs (114.7–200.4 mΩ cm2) of the 316L SS substrate were mainly attributed to the increased proportion of Cr oxide, while the oxide content of the coating was still relatively small. The change in surface morphology and current transient events are further discussed. [ABSTRACT FROM AUTHOR]

Common-mode voltage (CMV) is harmful to the motor bearing in converter systems. In order to reduce the high amplitude CMV and balance the neutral-point potential (NPP) of back-to-back three-level neutral-point clamped (NPC) converters, a simple dual-side zero-sequence voltage (ZSV) injection method based on carrier-based pulsewidth modulation (CBPWM) is proposed in this article. Two optimal ZSVs are injected into the rectifier side and inverter side, respectively, which can reduce the amplitude of CMV to 1/6 of the dc-bus voltage and balance the NPP effectively at the same time. This proposed method based on CBPWM is much easier to be implemented compared with the space vector pulsewidth modulation (SVPWM)-based method. Experimental results demonstrate the effectiveness of the proposed method.

• Additive manufacturing improves BP material properties and structural design. • Surface engineering like nanocoating enhances BP corrosion resistance. • Integrated bipolar plates evolve into next innovation of PEM water electrolyser. • Hydrogen energy reversible systems are expected for energy transformation. Hydrogen energy, whether in generation plants or utilization facilities, plays a decisive role in the mission to achieve net-zero greenhouse gas emissions, all to minimize pollution. The growing demand for clean energy carrier steadily accelerates the development of hydrogen production processes, and therein proton exchange membrane (PEM) water electrolysis is deemed a promising long-term strategy for hydrogen preparation and collection. This review retrospects recent developments and applications of bipolar plates (BPs) as key components in PEM fuel cells and water electrolysers. The main content includes multifaceted challenges in the R&D or fabrication of BPs and potential future trends have also been proposed. Specific details cover the BPs matrix (metallic materials and carbon composites) and the surface coating types (metal and compound coatings, carbon-based coatings, and polymer coatings), as well as the influence of flow field design for mass transport. Long-term development and feasible researches of BPs are prospected. Especially in the following aspects: (1) Structural and functional integration of components, such as material fabrication and flow field geometry optimization using 3D printing technology; (2) Introduction of environment-friendly renewable energy for hydrogen production; (3) Research on hydrogen energy reversible systems; (4) Composition optimization of surface coatings based on computational materials science and (5) systematic design expected to evolve into the next generation of BPs. [ABSTRACT FROM AUTHOR]

In this article, an inductive power transfer (IPT) system is designed to power multiple loads with nearly constant load currents using repeater coils. In the proposed IPT repeater system, every two repeater coils are grouped into a repeater unit and the load is connected to the first repeater coil in each repeater unit. It is deduced that the constant load current can be obtained when only considering the coupling coefficients between any two adjacent coils and omitting the coil resistances. Thus, the load power can be regulated independently, which greatly simplifies the power control design. A feasible magnetic structure is designed to meet the requirement that the coupling coefficients between the nonadjacent coils can be omitted. The relationship between the load resistances to achieve equal power distribution when considering coil resistances is derived. The proposed IPT system can be used to power gate drivers of the multiple submodules (SMs) that are connected in series in the modular multilevel converter (MMC). An experimental setup with six loads is constructed where the distance between two adjacent repeater units is 65 mm. The maximum system efficiency is around 60%.

This paper proposes a wireless power repeater system for long-distance and multiple-load applications with equal power load at each repeater. Each repeater performs as a power relay that not only receives and transmits power but also supplies power to its local load. The main contribution of this paper is to provide the design methodology of a distributed power-relay system. First, it provides the mathematical model of the power distribution among the power relays, indicating that the inductances and resistances can affect the power distribution. Second, it provides the power transfer capability of a power-relay system based on the quality factor and efficiency requirement, indicating the maximum achievable number of power relays in a system. Aiming at practical applications, this paper provides the guideline for the circuit parameter design to achieve equal power distribution. Two typical examples are proposed to realize equal power distribution. The identical Mn and different Rn examples are selected for implementation. The coil size is 400 mm × 400 mm, and the eight power relays achieve a transfer distance of 3.2 m with a total power of 760 W and an efficiency of 70%. Experimental results validate that equal power distribution is achieved for the multiple loads across a long distance. Each power relay dissipates about 95-W power in its local load with a power variation limited to ±2%.

Proton exchange membrane water electrolyser (PEMWE) is crucial for contemporary hydrogen generation technology. However, the corrosion of bipolar plates (BPPs) poses a significant challenge primarily due to the high anodic potential and acidic environments throughout the operation. This study compares the performance of the innovative Ti-Nb-N film modified 316L stainless steel and Ti bipolar plates under simulated PEMWE operating conditions. Interfacial contact resistance (ICR) experimental results confirm that the Ti-Nb-N film significantly reduces the ICR of the modified Ti plates and 316L stainless steel by approximately 77.7% and 91.0% respectively. According to the polarization tests, the Ecorrof the modified 316L stainless steel and Ti plates shows positive shifts, increasing by 318.49 mV and 376.64 mV, respectively. The Ti-Nb-N film modified 316L stainless steel plates are durable up to 1.4 V (vs. Ag/AgCl), while modified Ti plates maintain performance up to 1.8 V (vs. Ag/AgCl).

The water content of proton exchange membrane fuel cells (PEMFCs) affects the transport of reactants and the conductivity of the membrane. Effective water management measures can improve the performance and extend the lifespan of the fuel cell. The water management state of the stack is influenced by various external operating conditions, and optimizing the combination of these conditions can improve the water management state within the stack. Considering that the stack's internal resistance can reflect its water management state, this study first establishes an internal resistance-operating condition model that considers the coupling effect of temperature and humidity to determine the variation trend of total resistance and stack humidity with single-factor operating conditions. Subsequently, the water management state optimization method based on the ANN-HGPSO algorithm is proposed, which not only quantitatively evaluates the influence weights of different operating conditions on the stack's internal resistance but also efficiently and accurately obtains the optimal combination of five operating conditions: working temperature, anode gas pressure, cathode gas pressure, anode gas humidity, and cathode gas humidity to achieve the optimal water management state in the stack, within the entire range of current densities. Finally, the response surface experimental results of the stack also validate the effectiveness and accuracy of the ANN-HGPSO algorithm. The method mentioned in this article can provide effective strategies for efficient water management and output performance optimization control of PEMFC stacks.

Large-scale energy storage technology is crucial to maintaining a high-proportion renewable energy power system stability and addressing the energy crisis and environmental problems. Solid gravity energy storage technology (SGES) is a promising mechanical energy storage technology suitable for large-scale applications. However, no systematic summary of this technology research and application progress has been seen. Therefore, the basic concept of SGES and conducted a bibliometric study between 2010 and 2021 is first introduced to show SGES technology's evolution and predict future trends. Various SGES technologies have been intensively investigated in equipment, principles, materials, progress, and mathematical models. Furthermore, the key equipment's impact on SGES is discussed, and a systematical classification of SGES's different technical routes is conducted. Based on the technical characteristics, the advantages and disadvantages of SGES's different technical routes are discussed through their comparison. The decision tree is made for different technical route selections to facilitate engineering applications. Moreover, this paper also proposed the evaluation method of large-scale energy storage technology and conducted a comparative analysis of solid gravity energy storage with other large-scale energy storage technologies. Compared with other large-scale energy storage technologies, SGES has many advantages: high cycle efficiency (80 %–90 %), large energy storage capacity (up to several GWh), good geographical adaptability, and economy. Finally, the SGES's possible application scenarios and market scale assessment are presented based on SWOT analysis.

•A new multi-stage compression and heat recovery on A-CAES system is proposed.•An in-house code is developed to evaluate the performance of the proposed system.•The effect of several control parameters on the overall performance is discussed.•An optimized algorithm for the heat exchanger in CAES system is proposed.

The construction of the air electrode structure is critical in the rechargeable zinc-air batteries. So far, the majority of previous articles have been reported on the process in boosting electrocatalytic bifunctional oxygen reaction activity. Nevertheless, the reason that caused the deterioration of air electrodes has been rarely investigated, which dramatically influences cell performance. Herein, self-supported MnO2bifunctional electrocatalysts on nickel foam are integrated with the gas diffusion layer to form air electrodes. The charge voltage of the as-prepared electrode used in rechargeable zinc-air battery is reduced by 1.82% and the discharge voltage is decreased by 5.25% after 1000 cycles at the current density of 20 mA cm?2under the mode of 5 min charge and 5 min discharge, which demonstrate the feasibility of the novel electrode structure design. Besides, The X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS) were conducted to analyze the change of composition, structure, and performance. The origin of the decrease of the discharge profile was analyzed. Experimental studies revealed that the main cause of voltage loss is mainly attributed to the destroyed gas diffusion structure (at large current densities) and the activation loss of MnO2caused by the (oxy)hydroxide film (at small current densities). The destroyed gas diffusion structure gives rise to the poor oxygen transfer and further water flooding due to the formation of large pore caused by oxygen evolution in the charging process and increased hydrophilicity by the carbon oxidation. Meanwhile, the film growing overtop of the electrocatalysts would result in mass transfer and activation losses.