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Given the global demand for green energy, the battery industry is positioned to be an important future technology. Lithium-ion batteries (LIBs), which are the most widely used battery in the market, are the focus of various research and development efforts, from materials to systems, that seek to improve their performance. The separator is one of the core materials in LIBs and is a significant factor in the lifespan of high-performance batteries. To improve the performance of present LIBs, electrochemical testing and related surface analyses of the separator is essential. In this paper, we prepared a ceramic (Boehmite, γ-AlOOH) coated polypropylene separator and a porous polyimide separator to compare their electrochemical properties with a commercialized polypropylene (PP) separator. The prepared separators were assembled into nickelmanganese-cobalt (NMC) cathode half-cell and full-cell lithium-ion batteries. Their cycling performances were evaluated using differential capacity and electrochemical impedance spectroscopy with ethylene carbonate:dimethylcarbonate (EC:DMC) electrolyte. The ceramic coated polypropylene separator exhibited the best cycle performance at a high 5 C rate, with high ionic conductivity and less resistive solid electrolyte interphase. Also, it was confirmed that a separator solid electrolyte interface (SSEI) layer formed on the separator with cycle repetition, and it was also confirmed that this phenomenon determined the cycle life of the battery depending on the electrolyte.

In this study, we studied the surface and mechanical properties of multiple additives as well as the initial plating properties of individual additives. With the individual additive groups, copper crystals tended to converge at a stage above the critical amount of additive. When chloride ions were added, large crystals formed at several places on the surface. Thereafter, small crystals were attached to and grew on the surface of the large crystals. When collagen and JGB (Janes Green B) were added individually, the crystals were more uniformly distributed on the surface as compared with the group with added chloride ions. In addition, starlike crystals were grown depending on the amount of addition. It was necessary to use multiple additives, which is why it is difficult to make a uniform surface layer with individual additives. Large crystals of more than 10 μm formed unevenly on the surface treated with multiple additives of chloride ions and MPSA (3-mercapto-1-propane sulfonic acid). Large crystals disappeared on the surface treated with additional collagen along with multiple additives. However, valley like shapes were observed on this surface, due to the large crystals. But, addition of JGB additives to this reduced the valley and formed a uniform plating layer. MPSA and 20 ppm of collagen were added as multiple additives, grain sizes increased by 93.5% (220 peak) and 172.3% (311 peak) compared with the non-additive group. As a result, tensile strength decreased by 24.5% and elongation increased by 17.8%. The crystal size was reduced 25.0% on average by the addition of 10 ppm JGB, which contributed to a 5.4% increase in tensile strength and a 16.0% decrease in elongation. The grain size and surface properties could be controlled by adding multiple combinations of additives. As a result, It was confirmed that mechanical properties could be controlled by the proper amount and the optimum combination of additives.

Sn-based perovskite solar cells have attracted much attention as the lead-free next generation of perovskite solar cells. However, their efficiency is still low (∼12%). One reason is that the carri...

In the present study, we report a simple method to prepare indium(III) selenide (In2Se3) nanocubes synthesized by laser ablation in aqueous medium. The morphological characterization carried out us...

Transition-metal (oxy)hydroxides with an abundance of redox metal sites are important for the development of electrochromic devices, rechargeable metal–air batteries, pseudo-capacitors, and industr...

Electrochemical water splitting technology for producing "green hydrogen" is important for the global mission of carbon neutrality. Electrocatalysts with decent performance at high current densities play a central role in the industrial implementation of this technology. This field has advanced immensely in recent years, as witnessed by many types of catalysts designed and synthesized toward industrially-relevant current densities (> 200 mA cm-2 ). By discussing recent advances in this field, we summarize several key aspects that affect the catalytic performance for high-current-density electrocatalysis, including dimensionality of catalysts, surface chemistry, electron transport path, morphology, and catalyst-electrolyte interplay. We highlight the multiscale design strategy that considers these aspects comprehensively for developing high-current-density electrocatalysts. We also put forward our perspectives on the future directions in this emerging field. This article is protected by copyright. All rights reserved.

Highly selective electrochemical reduction of CO2 (CO2RR) to multi-carbon (C2+) products at high current density remains a big challenge. Herein we report copper oxide nanosheets (CuO-st) for selective electrochemical conversion of CO2 to C2+ products at high current density. Benefiting from the defect-rich structure verified by HR-TEM and XPS characterization and the designed gas diffusion electrode, such a CuO-st material exhibits CO2RR FE (C2+) of 86 and 80 % at 1.0 and 1.8 A cm−2, respectively, with excellent durability of 50 h @ 500mAcm−2 and storable lifetime for >10 months. Importantly, using quasi-situ XPS and in-situ Roman spectra, we have shown the first evidence for the presence of Cu (ǀ) during the eCO2RR on initial Cu (ǁ) material, and the proportion of Cu (ǀ) varies with the reaction current density. The rough and defective surface of CuO-st serves as a favorable reservoir to produce enough Cu (ǀ) to assist the C-C coupling, thus achieving selective CO2RR to C2+ products at high current density. Our study not only provides a new insight into CO2RR, but also suggests that in-situ forming active species from stable Cu (ǁ) materials during the reaction may be a good choice for the practical application, which will be very helpful to the development of cost-effective CO2RR electrocatalysts.

Mechanisms and characteristics of optimized main junction for 4H-SiC trench junction barrier Schottky (TMJBS) diodes were investigated by theories and experiments. From these simulation and experimental values, we can conclude that TMJBS device has better reverse performance, such as the best reverse blocking capability and lowest reverse surface leakage current than the conventional JBS and TJBS device while maintaining good forward characteristics. Furthermore, The large area TMJBS Diodes with high current density show the better reverse characteristics than the small area one at an acceptable forward characteristics. The TMJBS structure can significantly reduce the influence of the Schottky interface and is more suitable for manufacturing high current density and large area devices.

In this article, the design approach for a miniaturized high-current-density sheet electron beam (SEB) source has been reported. A study through simulation using COMSOL Multiphysics has been carried out to analyze the role of geometrical parameters of the hollow cathode in miniaturized SEB generation. These geometrical parameters play a very important role in defining the discharge inside the hollow cathode geometry and subsequent beam generation through a rectangular aperture. The hollow cathode diameter “D”, the length of the hollow cathode “L”, and the aspect ratio of the sheet beam defined by the aperture size in front of the hollow cathode region have been optimized for the generation of a SEB. The ratio of the length to the width of the rectangular aperture defines the aspect ratio of the SEB. It has been found that the beam aspect ratio plays an important role in the penetration of the accelerating field inside the hollow cathode geometry, which affects the transient behavior of the discharge. The hollow cathode dimensions have been optimized for the applied gap voltage varying between 15 and 25 kV, while the beam aspect ratio has been analyzed for the range between 5:1 and 12:1 keeping the fill factor constant.

SmTiO3/SrTiO3 interfaces are of potential interest for electronic devices as they exhibit novel electronic phenomena such as metal–insulator transitions. However, good transistor performance from t...

Ferroelectric tunnel junction (FTJ) with ultrathin 3 nm-thick Hf 0.5 Zr 0.5 O 2 (HZO) is investigated. The high current density up to 100 A/cm2 is at least 10 times higher than that in previously reported HZO FTJs. It is suitable for future nanoscale FTJ with a GΩ cell resistance for the application of in-memory computing. The insertion of a thin Al 2 O 3 interfacial layer is found critical to alter the switching polarity and increase current density.

Lithium-sulfur battery is one of the most promising next-generation energy storage devices due to its low cost and ultrahigh energy density. However, the uncontrolled formation of Li dendrites and shuttle effect seriously hinder its practical applications. To simultaneously address both fatal issues, herein, for the first time, we present a novel Mo2C quantum dots (MQDs) anchored N-doped graphene functionalized interlayers (MQD@NG). The DFT calculations show that lithiophilic feature of Mo2C QDs, which can construct a fast electrolyte diffusion pathway for Li+ transportation and achieve uniform Li deposition. Moreover, the polar Mo2C QDs possess strong chemical adsorption of polysulfides. As a result, the lithium symmetric cells with MQD@NG interlayers achieve a dendrite-free lithium deposition over 1600 h at a high current density of 10 mA cm−2. The Li-S cells exhibit a high capacity of 1230 mAh g−1 at 0.2 C and a highly stable cycling performance over 400 cycles without obvious capacity fading. This work provides a new insight to design and fabricate high-energy and safe Li-metal-based batteries.

Carbon corrosion in catalysts is one of the main limitations of proton exchange membrane fuel cell (PEMFC) lifetime. Water flooding can accelerate the carbon corrosion rate in PEMFCs, especially at high current densities. Increasing the operation temperature can effectively mitigate water flooding and improve the water management performance of PEMFCs. However, elevated temperatures also increase the carbon corrosion reaction kinetics, accelerating the degradation of PEMFCs lifetime. To study the effects of temperature on carbon corrosion at high current densities, PEMFCs operating for 100 h at 65 °C and 90 °C under 1600 mA·cm−2 were investigated. The results showed that the electrochemical active surface area (ECSA) of the cathode catalyst layer decreased by 9.16% and 13.92% at 65 °C and 90 °C, respectively. The reduction rate of the catalyst layer in the nonflooding area increased as the operating temperature increased. However, the reduction rate decreased by 69.82% and 54.04% at 65 °C and 90 °C, respectively, at the outlet of the PEMFC. Therefore, water flooding is the key issue causing lifetime degradation, and water management is essential for PEMFCs that operate at high current densities, especially at the outlet of PEMFCs.

Highlights N-doped graphene-coated structure and mesoporous nano-sheet can efficiently boost active sites and stability for hydrogen and oxygen evolution reaction.NiCo@C-NiCoMoO/NF exhibits low overpotentials for HER (266 mV) and OER (390 mV) at ± 1000 mA cm−2.For water electrolysis, it can hold at 1000 mA cm−2 for 43 h in 6.0 M KOH + 60 °C condition. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00607-5., Developing highly effective and stable non-noble metal-based bifunctional catalyst working at high current density is an urgent issue for water electrolysis (WE). Herein, we prepare the N-doped graphene-decorated NiCo alloy coupled with mesoporous NiCoMoO nano-sheet grown on 3D nickel foam (NiCo@C-NiCoMoO/NF) for water splitting. NiCo@C-NiCoMoO/NF exhibits outstanding activity with low overpotentials for hydrogen and oxygen evolution reaction (HER: 39/266 mV; OER: 260/390 mV) at ± 10 and ± 1000 mA cm−2. More importantly, in 6.0 M KOH solution at 60 °C for WE, it only requires 1.90 V to reach 1000 mA cm−2 and shows excellent stability for 43 h, exhibiting the potential for actual application. The good performance can be assigned to N-doped graphene-decorated NiCo alloy and mesoporous NiCoMoO nano-sheet, which not only increase the intrinsic activity and expose abundant catalytic activity sites, but also enhance its chemical and mechanical stability. This work thus could provide a promising material for industrial hydrogen production. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00607-5.

Electrochemical alcohols oxidation offers a promising approach to produce industrial-relevant chemicals and facilitate coupled H 2 production. However, the corresponding current density is very low at moderate cell potential that substantially limits the overall productivity. Here, we report enrichment of alcohols in local environment over a cooperative catalyst of Au nanoparticles supported on cobalt oxyhydroxide nanosheets (Au/CoOOH), enabling alcohols electrooxidation at high current density. Specifically, the current density of benzyl alcohol electrooxidation can reach 523 mA cm− 2 at potential of 1.5 V vs. RHE. Experimental and theoretical results suggest that benzyl alcohol molecules are enriched on Au/CoOOH interface via strong d-π interaction. The enrichment has a broad substrate scope that involves alcohols with α-π bond including α-phenyl, C = C and C = O groups. Based on these findings, we design an intermittent potential (IP) strategy for long-term alcohol enrichment, achieving electrooxidation with current density of > 250 mA cm− 2 over 24 hours and promoted productivity.

The high degree of order in organic single crystals often leads to optimum charge transport properties and their robustness under high current density which is attractive for solid state lighting and laser technology. However, conventional method of single crystal growth based on physical vapour transport is unsuitable for device integration and large area applications. Here, we present a vacuum processed approach to prepare organic single crystals on inch sized substrates and integrate them into organic light emitting devices (OLED). The device performance are characterized in comparison to standard OLED based on amorphous materials.

Alkaline water electrolysis is a cost-effective approach to hydrogen production, but it suffers from low operational current densities (typically ⤠500 mA cm-2) and thereby a low hydrogen production rate. Herein, we report the fabrication of self-supported porous cobalt phosphide (Co-P) foam by electrochemical anodization of commercially available cobalt foam, followed by thermal oxidation and subsequent phosphorization. The as-obtained porous Co-P foam, compared to other control samples prepared under different conditions, shows outstanding electrocatalytic performance in alkaline electrolyte for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), requiring an overpotential of 290 mV for HER and 380 mV for OER, respectively, at a high current density of 1000 mA cm-2. Moreover, the electrolyzer consisting of two symmetric porous Co-P foam electrodes only requires a cell voltage of 1.98 V to operate at 1000 mA cm-2 for overall water electrolysis, with extraordinary stability of 4000 h, showing great potential for use in industrial alkaline water electrolysis., L. Liu acknowledges the financial support of Fundação para a Ciência e a Tecnologia (FCT, Portugal) Exploratory Grant (IF/01595/2014/CP1247/CT0001) and I.C.N. thanks to project BioTecNorte (operation NORTE-01-0145-FEDER-000004) and Centre of Chemistry, University of Minho (UID/QUI/00686/2013 and UID/QUI/0686/2016). Z. P. Yu acknowledges the financial support of China Scholarship Council (Grant No. 201806150015)., info:eu-repo/semantics/publishedVersion

Highly ordered TiO2 nanoribbons are obtained by anodizations in NH4F electrolyte under high current density. Although intact TiO2 nanoribbons appear, there are still nanotubes beneath nanoribbons. It is reasonable to speculate that TiO2 nanoribbons evolve from TiO2 nanotubes. While the applied current is high, the electronic current is also high, which gives rise to lots of oxygen bubbles. With the accumulation of oxygen bubbles, oxygen bubbles must expand upward and rupture finally. Therefore, gas flow from oxygen bubbles results in the generation of micro-liquid-flow. Because of micro-liquid-flow, the nanotube wall is corroded and scoured. The corrosion of upper pore wall is the most sever and thus the upper pore wall becomes the thinnest locality of nanotube wall. As a result, the nanotubes can collapse easily. Finally, one TiO2 nanotube is divided into several TiO2 nanoribbons while there is still intact tube beneath nanoribbons.

In this article, a trigger unit has been implemented to generate a high-current-density electron beam from a pseudospark (PS) discharge-based electron gun. A trigger pulse power supply unit has been designed and developed to provide the seed electrons from the ferroelectric cathode (FEC). The FEC has been used inside the hollow cathode cavity of a single-gap PS discharge-based electron gun. The electron gun has been operated in the self-breakdown as well as the trigger-based breakdown mode. A comparative analysis has also been performed between self-breakdown and trigger breakdown modes with the developed trigger unit’s help for different applied gap voltages ranging between 0 and 16 kV. The designed trigger unit is based on a high-voltage-gain isolated dc–dc converter and a pulse-forming network. It is compact and capable of generating a negative pulse of ~–5 kV with a pulsewidth of ~500 ns. It provides better control over PS discharge to produce a high-current-density electron beam.

Water electrolysis is an efficient approach for high-purity hydrogen production. However, the anodic sluggish oxygen evolution reaction (OER) always needs high overpotential and thus brings about superfluous electricity cost of water electrolysis. Therefore, exploiting highly efficient OER electrocatalysts with small overpotential especially at high current density will undoubtedly boost the development of industrial water electrolysis. Herein, we used a simple hydrothermal method to prepare a novel FeOOH–CoS nanocomposite on nickel foam (NF). The as-prepared FeOOH–CoS/NF catalyst displays an excellent OER performance with extremely low overpotentials of 306 and 329 mV at 500 and 1000 mA cm−2 in 1.0 M KOH, respectively. In addition, the FeOOH–CoS/NF catalyst can maintain excellent catalytic stability for more than 50 h, and the OER catalytic activity shows almost no attenuation no matter after 1000 repeated CV cycles or 50 h of stability test. The high catalytic activity and stability have exceeded most non-noble metal electrocatalysts reported in literature, which makes the FeOOH–CoS/NF composite catalyst have promising applications in the industrial water electrolysis.

Conventional magnetron discharge with a graphite target is a technology used worldwide to deposit thin films for a large range of applications. In the last decade, the high current density sputtering regime stands out as a very interesting alternative allowing the tailoring of coating properties. The peak power density normalized to the target area can exceed 107 W m−2, leading to an important ionization of the sputtered atoms. In this paper we focused on the electrical characterization of a magnetized plasma operated at average gas pressure (5 Pa; Ar and He) with a graphite target. A cross-correlation with a high-speed gated camera and optical emission spectroscopy measurements of the plasma evolution is also given. The analysis of the plasma–surface interaction zone on the target unveiled the physical mechanisms associated with the high current density range (1.8–32.5 A cm−2), corresponding to several regimes of discharge. For graphite, it will be demonstrated that the gas rarefaction induced by the vapor wind is negligible due to its low sputtering yield. Thus, the gas recycling is the dominant mechanism sustaining the discharge, even for the higher discharge current regime when a spot is present. Spokes and other instabilities were also identified and are discussed.

Li7La3Zr2O12(LLZO)-based ceramics as promising solid-state electrolytes (SSEs) have received much attention for use in high-energy lithium (Li) metal batteries. However, the Li growth through the solid garnet electrolyte under a low current density hinders its practical application. In this work, the Cu doped Li3Zn was designed to guide uniform Li deposition by magnetron cosputtering and an in situ alloying reaction on Li6.5La3Zr1.5Ta0.5O12 (LLZTO) pellets. After introducing the composite layer, a small interfacial area specific resistance (∼30 Ω·cm2) can be obtained. Improved lithium plating/stripping performance, including a long-life span of 450 h (under a current density of 0.8 mA cm-2 without short circuit) and a high critical current density (CCD) of 2.8 mA cm-2 is performed by the composite interlayer with a Zn:Cu ratio of 10:1. And the Li/Cu-Li3Zn SSEs/LFP full cell exhibits good electrochemical performance. Accordingly, the Li deposited behavior in the Li plating/stripping process at the intermediate layer is discussed in detail. This work provides a new sight for the alloy interface designed on the solid-state garnet SSEs for high performance lithium metal batteries under high current density.

Cu wires (CuWs) are widely used as electric transmission lines. However, their limited thermal and chemical stabilities become challenges under the high-power and harsh environment. Graphene is regarded as an ideal protective barrier for CuW benefiting from its impermeability to all atoms and molecules. Particularly, the excellent hydrophobicity of vertical graphene (VG) will strengthen its protective capability as a corrosion and oxidation barrier. Herein, VG is directly synthesized on CuW by plasma-enhanced chemical vapor deposition method. The hydrophobic VG coating with a high water contact angle can effectively exclude the corrosive liquid and moisture from CuW surface and prevent their further penetration. Consequently, the electrochemical corrosion rate of VG-CuW is reduced by ∼ 13, 8, and 2 times, compared with bare CuW, VG-CuW with hydrophilic treatment, and CuW coated with thick horizontal graphene layers, respectively. Negligible oxidation occurs on VG-CuW after the long-time exposure to humid air at ∼ 200 °C along with the largely enhanced tolerance under high-current operating condition. This study reveals the impressive potentials of hydrophobic VG as a robust corrosion and oxidation barrier for metal wires used in high-power cables and electronic devices in harsh environment.

The poor performance of conventional powdery catalysts under large current density and the slow kinetics of the Volmer step limit the large-scale application of alkaline hydrogen generation. Here, we report the preparation of freestanding surface disordered NiCu solid solution as an ultrastable hydrogen evolution reaction electrode. The introduction of ammonium ion could tailor the reduction/nucleation rate of metal ions during the hydrothermal process, thus contributing to its unique intertwined 3D microstructure. The catalyst exhibits superior HER activity with an overpotential of 322 mV at 1000 mA cm-2, and limited degradation after 110 h continuous operation at 1000 mA cm-2. Density functional theory calculations confirm that the substitution of Cu could accelerate the hydroxyl desorption process (OHads + e- → OH-) and thereby enhance the overall kinetics of the Volmer step. Our work demonstrates the strong efficacy of optimizing catalysts' structures and facilitating intermediate desorption for boosting industrial-scale alkaline HER performance.

This paper presents an overall optimization procedure and the electrical performances of 1.2 kV/10 A 4H-SiC junction barrier Schottky (JBS) diodes with high current density. To achieve high current density, the epi-layer, the design parameters for active region including p-grid width and cell pitch, and the field limiting ring for edge termination were optimized with analytic calculation to estimate forward electrical performances and with Silvaco atlas™ simulator to estimate reverse electrical performances. Based on the systematic design, the JBS diodes were fabricated and electrically characterized. The experimental results showed that the breakdown voltage (BV) of JBS diode was significantly sensitive to field limiting ring (FLR) space and that the JBS diode with the ratio of pure Schottky contact area to total active area of 0.75 and the FLR space of 1.25 μm had optimum electrical performances such as a forward current density of 370 A/cm2, a reverse leakage current below 20 μA at the reverse anode voltage of 1.2 kV, and the BV of 1400 V. These were in coincidence with the simulation results within 10% error.

Large-scale production of green hydrogen by electrochemical water splitting is considered as a promising technology to address critical energy challenges caused by the extensive use of fossil fuels. Although nonprecious nickel-based catalysts work well at low current densities, they need large overpotentials at high current densities, which hinders their wide applications in practical industry. Here we report a hydroxide-mediated nickel-based electrocatalyst for high-current-density hydrogen evolution, which delivers a current density of 1000 mA cm−2 at an ultralow overpotential of 97 mV. Combined X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) results show charge redistribution of Ni sites caused by Mo and surface Fe, which can stabilize the surface nickel hydroxide at high current densities for promoting the water dissociation step. Combined in situ XAS, quasi in situ XPS, and density functional theory calculations indicate that Fe plays an important role in the improved catalytic activity. Such a catalyst is synthesized at the metre-size scale and delivers a current density of 500 mA cm−2 at 1.56 V in overall water splitting, demonstrating its potential for practical use. This work highlights a charge engineering strategy to design efficient catalysts for high current density electrochemical applications.

As a clean energy carrier, hydrogen has priority in decarbonization to build sustainable and carbon-neutral economies due to its high energy density and no pollutant emission upon combustion. Electrochemical water splitting driven by renewable electricity to produce green hydrogen with high-purity has been considered to be a promising technology. Unfortunately, the reaction of water electrolysis always requires a large excess potential, let alone the large-scale application (e.g., >500 mA cm−2 needs a cell voltage range of 1.8–2.4 V). Thus, developing cost-effective and robust transition metal electrocatalysts working at high current density is imperative and urgent for industrial electrocatalytic water splitting. In this review, the strategies and requirements for the design of self-supported electrocatalysts are summarized and discussed. Subsequently, the fundamental mechanisms of water electrolysis (OER or HER) are analyzed, and the required important evaluation parameters, relevant testing conditions and potential conversion in exploring electrocatalysts working at high current density are also introduced. Specifically, recent progress in the engineering of self-supported transition metal-based electrocatalysts for either HER or OER, as well as overall water splitting (OWS), including oxides, hydroxides, phosphides, sulfides, nitrides and alloys applied in the alkaline electrolyte at large current density condition is highlighted in detail, focusing on current advances in the nanostructure design, controllable fabrication and mechanistic understanding for enhancing the electrocatalytic performance. Finally, remaining challenges and outlooks for constructing self-supported transition metal electrocatalysts working at large current density are proposed. It is expected to give guidance and inspiration to rationally design and prepare these electrocatalysts for practical applications, and thus further promote the practical production of hydrogen via electrochemical water splitting.

Dynamic Avalanche (DA) phenomenon poses a fundamental limit on the operating current density, turn-off power loss as well as reliability of MOS-bipolar devices. Overcoming this phenomenon is essential to ensure their safe operation in emerging electric transport. In this work, detailed analysis of 1.2 kV trench gated IGBTs are undertaken through experiments and calibrated TCAD simulations to show the fundamental cause of the DA as well as a method to achieve DA free design for ultra-high current density operation and reliability in 1.2 kV Si-IGBTs.

In this paper we present a Superjunction IGBT (Super-IGBT) based upon Deep Trench (DT) Superjunciton technology to cope with high current density, smaller chip size and low switch losses. The current density of Super-IGBT is 550A/cm2(CP test:20A@1.8V), almost close to Si-IGBT limit. Moreover, under the same switch condition, Super-IGBT show 54% lower turn-on loss, 15% lower turn-off loss and 60% chip size shrink compared with the 650V FS-IGBT. Super-IGBT is favorable for high power and high frequency applications.

The bipolar degradation of Deep-p encapsulated 4H-SiC trench MOSFETs was investigated by using the pulse-current conduction system up to ultra-high current density. The fabricated MOSFETs exhibit the low hole injection compared with the PN diodes and conventional MOSFETs, resulted in the fabricated MOSFETs suppressed the bipolar degradation up to a current density of 3000 A/cm2.

Lithium-metal anodes with high theoretical capacity and ultralow redox potential are regarded as a "holy grail" of the next-generation energy-storage industry. Nevertheless, Li inevitably reacts with conventional liquid electrolytes, resulting in uneven electrodeposition, unstable solid electrolyte interphase, and Li dendrite formation that all together lead to a decrease in active lithium, poor battery performance, and catastrophic safety hazards. Here, we report a unique nonporous gel polymer electrolyte (NP-GPE) with a uniform and dense structure, exhibiting an excellent combination of mechanical strength, thermal stability, and high ionic conductivity. The nonporous structure contributed to a uniform distribution of lithium ions for dendrite-free lithium deposition, and Li/NP-GPE/Li symmetric cells can maintain an extremely low and stable polarization after cycling at a high current density of 10 mA cm-2. This work provides an insight that the NP-GPE can be considered as a candidate for practical applications for lithium-metal anodes.

In this article, the design approach for a ${V}$ -band miniaturized oscillator with a pseudospark-based high-current-density sheet electron beam source is presented. The hollow cathode electron gun has been designed and developed. In the experiment, the ~10-A current in the hollow-cathode phase has been measured. The high-frequency structure comprised of a truncated sine waveguide slow wave structure (TSW SWS) with wideband-matched output couplers has been designed, optimized, and simulated. The simulations show good transmission characteristics of the structure. The operation of a backward-wave oscillator with the designed TSW SWS driven by a 10-A, 40-kV sheet electron beam has been investigated by using 3-D particle-in-cell simulations. The maximal output power of 70 kW has been attained in the simulation. Frequency tuning within the 10-GHz frequency band has been demonstrated.

In this study, on-line mass spectrometry is used to determine hydrogen permeation during proton exchange membrane water electrolyzer (PEM-WE) operation for a wide range of current densities (0–6 A cm−2) and operating pressures (1–30 bar, differential pressure). H2 permeation measurements with a permeation cell setup, i.e., without applying a current, show a linear correlation between permeation rate and H2 partial pressure, indicating diffusion as the main crossover mechanism. Measurements with full membrane electrode assemblies (MEAs) during PEM-WE operation reveal a significant increase of the gas permeation rate at high current densities, by up to ≈20-fold at 1 bar H2 and up to ≈1.2-fold at 30 bar H2 (Nafion® 212 or Nafion® 117 membrane; Ir-black (anode) and Pt/C (cathode)). Recently, H2 super-saturation of the ionomer phase in the cathode catalyst layer was shown to be the reason for this increase, and we discuss the impact of this effect for different electrode compositions and operating conditions. Finally, the determined H2 permeation rates and electrolyzer performance are used to discuss the overall PEM-WE efficiency for different membrane thicknesses and it is shown that the formation of an explosive gas mixture in the anode at low current densities requires additional mitigation strategies.

We present experimental characterization of a 20-kV, 130-mA thermionic electron gun, which is a component of a ${W}$ -band traveling-wave tube (TWT) power amplifier. The electron beam is strongly focused by a 6.6-kG permanent magnet solenoid, producing a peak current density up to 800 A/cm2. The cathode temperature, focus electrode voltage, and modulating anode voltage are varied to characterize the emitted cathode current and beam transport through the beam tunnel of the TWT RF circuit. We observe the variation of the cathode current from 107 to 155 mA and peak beam transmission of 95% measured at the collector. Experimental results are compared to 2-D simulations with the electron gun and collector design code MICHELLE.