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This work describes a new type of sensor for growth process monitoring named broadband cavity-enhanced optical flux monitoring sensor (BBCE-OFM). Like existing optical flux monitoring (OFM) solutions, it relies on absorption spectroscopy. However, the implementation of an optical cavity reduces the measurement uncertainty, enabling efficient operation even at very low growth rates. Using the BBCE-OFM sensor mounted in our solid-source oxide molecular beam epitaxy reactor, we achieved an uncertainty of ±2% on the measurement of Sr and Ti growth rates in SrTiO3 at around 1 Ml/min, to be compared to the ±16% obtained in the same conditions using a conventional OFM setup. Furthermore, our sensor architecture, based on an echelle monochromator and LEDs replacing the hollow cathode lamps used in standard OFM sensors, is more robust against drift. [ABSTRACT FROM AUTHOR]

The three-body fragmentation dynamics of benzene trications C 6 H 6 3 + induced by 200 eV electron-impact produced by a photoemission cathode is investigated. All three fragment ions are detected in coincidence, and their momentum vectors are determined by employing a COLTRIMS reaction microscope. The detailed kinematical information of three deprotonation fragmentation channels of H+ + C 3 H 2 + + C 3 H 3 + , H+ + C 2 H 3 + + C 4 H 2 + , and H+ + C 2 H 2 + + C 4 H 3 + are obtained. By analyzing the momentum and energy correlation spectra among all the three fragment ions, we find that all the three channels are primarily generated by sequential fragmentation processes. Each channel has two deprotonation pathways, corresponding to proton emission in the first or second step of sequential fragmentation, respectively. These results provide insight into the mechanisms and dynamics of deprotonation and ring-breaking reactions in the three-body fragmentation processes of aromatic ring molecules. [ABSTRACT FROM AUTHOR]

The relative errors of virtual cathodes calculated by using the one-dimensional virtual cathode theory are analyzed and discussed. The studies of the error analysis show that the cathode temperature is the major factor affecting the calculated results of virtual cathodes, especially for calculations of the virtual cathode width. The smaller the virtual cathode produced by a hot cathode, the more significant the relative error of the virtual cathode caused by the uncertainties of electron emission parameters. Using the accurate cathode temperature, the potential barrier and the spatial width of virtual cathodes generated by a tungsten filament are calculated with experimental and theoretical electron emission parameters. The calculated results show that there is a strong linear correlation between the potential barrier of the virtual cathode and the heating current of the tungsten filament, which is independent of the electron collection current. With the increase in the heating current, the variation of the virtual cathode width is very sensitive to the relation between the electron collection current and the heating current. [ABSTRACT FROM AUTHOR]

Studying ionic wind is crucial for deepening our comprehension of electrical discharge processes and refining their application in industrial technologies. This research investigates the behavior of needle–needle electrode using high-speed schlieren imaging techniques, focusing on the dynamics of ionic wind and its influence on spark discharge channel formation. Observations indicate that the ionic wind generated during corona discharge provides a structured pathway that significantly guides the development of spark discharge channels, particularly evident in horizontal configurations. Our findings reveal that the velocity and density of the ionic wind increase with decreasing curvature radius of the needle tip, thereby enhancing its guiding effect. Furthermore, the spark discharge channel forms through the convergence of positive and negative streamers, which meet near the cathode, leading to substantial disturbances in the surrounding flow field post-discharge. This research highlights the intricate relationship between corona and spark discharges, demonstrating the critical role of ionic wind in influencing discharge channel morphology and offering insights for future applications in plasma and electrostatic-based technologies. [ABSTRACT FROM AUTHOR]

Pulsed secondary electron multipacting (SEM) cathodes with channel-type structures have been developed. The electron emission performance of these cathodes was investigated using theoretical and particle-in-cell simulation methods. The results revealed that the electrical conductivity of the channel wall material is crucial to the performance of the cathodes. Materials with low conductivity cause the SEM process in the multipacting channel to stop quickly due to the positive charges deposited on the channel wall. These positive space charges, generated by the SEM process, create a space-charge field that reduces the impact energy of electrons on the channel wall, thereby decreasing the secondary electron emission yield. Consequently, materials with high electrical conductivity and high secondary electron emission yield, such as SnO 2 , are advantageous for the SEM process, leading to stable current output from the cathodes with high current density. For a SnO 2 cathode with three multipacting channels, an output current density of 242 A/cm 2 was achieved. [ABSTRACT FROM AUTHOR]

Layered manganese transition metal oxides, such as NaMnO2, have attracted great interest due to the low cost and high capacity. However, complex phase transitions in NaMnO2 lead to poor cycling stability. The introduction of Li doping has been confirmed to improve the performance of NaMnO2. O3-type NaLi1/3Mn2/3O2 (NLMO), synthesized in 2021, has demonstrated excellent electrochemical performance. Notably, irreversible Li interlayer migration (Li migrates from the transition metal layer to the alkali metal layer) has been observed during cycling, which is related to the electrochemical performance. Therefore, it is crucial to understand the mechanism underlying Li interlayer migration in O3-NLMO. However, the environment of Li interlayer migration on cycling is complex and involves interlayer spacing, Na-ion concentration, the degree of O-ion oxidation, and phase transition. Here, in this work, we utilized the first-principles method to decouple the coupling factors influencing the Li interlayer migration. Through analyzing the impact of the single-factor on Li interlayer migration, we aim to identify the crucial factors affecting this process. Our results show that a decrease in Na-ion concentration and an increase in O-ion oxidation degree promote the Li interlayer migration, while the O–P phase transition suppresses the Li interlayer migration. Interlayer spacing was found to play a less influential role in Li interlayer migration. Our investigations provide effective strategies for the subsequent regulation of Li interlayer migration. [ABSTRACT FROM AUTHOR]

Rechargeable multivalent-ion batteries are attractive alternatives to Li-ion batteries to mitigate their issues with metal resources and metal anodes. However, many challenges remain before they can be practically used due to the low solid-state mobility of multivalent ions. In this study, a promising material identified by high-throughput computational screening is investigated, ε-VOPO4, as a Mg cathode. The experimental and computational evaluation of ε-VOPO4 suggests that it may provide an energy density of >200 Wh kg-1 based on the average voltage of a complete cycle, significantly more than that of well-known Chevrel compounds. Furthermore, this study finds that Mg-ion diffusion can be enhanced by co-intercalation of Li or Na, pointing at interesting correlation dynamics of slow and fast ions.

Hollow cathodes are an integral part of ion, and Hall thrusters are used for electric propulsion in deep space missions and in commercial communications satellites. Hollow cathodes are known to operate in a quiescent "spot mode" and in a noisy "plume mode" in which plasma instabilities generate erosive energetic ions. The onset of the plume mode in hollow cathodes has been defined historically as when the keeper voltage oscillation values exceed 5 Vpp (peak-to-peak). Using a LaB6 hollow cathode in a vacuum chamber setup that simulates operation in ion and Hall thrusters, a set of emissive and Langmuir probes have been used to investigate the plasma properties associated with plume mode onset as a function of discharge current and gas flow rate. We find that the plume mode onset occurs at even less than 2 Vpp of the keeper voltage for the 5–75 A hollow cathode investigated here and starts at higher gas flow rates than expected from the traditional 5 Vpp metric used by those in the field. Mode competition and coupling between three different instabilities observed in the near-cathode plume affect the overall plasma oscillation levels that are correlated to energetic ion production. We find that the plasma oscillation levels measured by in situ plasma diagnostics are more indicative of the presence of oscillations and the generation of energetic ions than indirect keeper voltage measurements. [ABSTRACT FROM AUTHOR]

The unstable plume mode of hollow cathodes should be avoided in practical applications because it severely degrades the overall cathode lifetime. In this study, we investigate the spot-plume transition and plasma stability characteristics of an unused segmented lanthanum hexaboride emitter. The expansion of the unstable plume mode region is observed during a discharge experiment. Subsequently, the segmented emitter is retrieved, the inner surface of the emitter is observed, and the work function on the surface is measured at room temperature. The emitter surface exhibits color variations with oxygen and carbon detection. The downstream edge shows the original purple color and almost no degradation in the work function. The high temperature in this region promotes the desorption of carbon and oxygen. In the spot mode, this region mainly contributes to thermionic electron emission; therefore, the discharge voltage in the spot mode does not change during the discharge experiment. Carbon or carbide is detected in the middle of the axial direction on the emitter surface, where the surface temperature is not sufficiently high to desorb carbon during discharge. Based on the surface analysis results, the dominant substance in the region where carbon is detected was lanthanum carbide. An increase in the work function is indicated in the region, which appears to increase the plasma instability. According to previous studies, an increase in the work function results in a rise in the potential in the emitter, and an increase in the electron temperature in the outside plume region induces the plasma instability. Further investigation is needed to understand the mechanism connecting the rise in the work function and the rise in the electron temperature in the plume region. [ABSTRACT FROM AUTHOR]

Laser Thomson scattering is a minimally intrusive diagnostic technique for determining electron temperature, density, and bulk velocity in plasma systems. Advances in technology have made possible the application of Thomson scattering to electric propulsion-relevant plasma systems, with reported electron number-density detection limits as low as 1 × 10 16 m − 3 , and electron temperatures from one-to-tens eV. However, the implementation of laser Thomson scattering in large vacuum testing facilities, wherein electric propulsion devices are tested, remains a challenge. This work presents the implementation of a laser Thomson scattering system in a large vacuum test facility at the Georgia Tech High Power Electric Propulsion Laboratory. The diagnostic was optimized for maximum light-collection efficiency and ease of re-alignment while the facility is at vacuum. The high light-collection efficiency allowed reduced accumulation times to achieve the target detection limit of 1 × 10 17 m − 3 . The diagnostic is used to measure axial electron property profiles in the near-field plume of a lanthanum hexaboride hollow cathode operating at 25 A on krypton at a background pressure of 1.3 × 10 − 6 Torr—Kr. The diagnostic is quantitatively compared to similar systems in the literature. The resulting axial points, collected from 2 to 8 mm downstream of the cathode keeper orifice, are qualitatively and quantitatively compared with simulations and experimental measurements made with electrostatic probes and laser-induced fluorescence. The main quantitative difference between measured values and results is the one to two order of magnitude difference in the peak electron density, being attributed to the relative size and location of the external anode with respect to the cathode keeper. [ABSTRACT FROM AUTHOR]

A layered sodium-ion battery cathode, O3/P3/P2-type NaNi1/3Mn1/3Fe1/3O2, has been systematically investigated by first-principles density functional theory to explore the detailed structural and Na-ion diffusion behavior during desodiation. Our results suggest that the (NaO6) spacing is greatest in the P3 phase and lowest in the O3 phase, with the P2 phase exhibiting intermediate spacing. During desodiation, the intermediate stages have a greater (NaO6) spacing than the initial and final stages. The great (NaO6) spacing facilitates the formation of the P3 phase, resulting in the structural evolution of NaxNi1/3Mn1/3Fe1/3O2 from the O3 to the P3 phase at x ≈ 0.59, finally reaching the O3 structure again at x ≈ 0.12. The electronic structure clearly proves that both Ni and Fe are active in O3/P3/P2-type NaxNi1/3Mn1/3Fe1/3O2. Ni2+ is oxidized to Ni3+ as Na content decreases from x = 1 to x = 0.66, then further oxidized to Ni4+ at x = 0.33, and finally, Fe3+ → Fe4+ oxidation occurs at x = 0. In the Na ion diffusion behavior, the order of the barrier is O3 (0.82 eV) > P2 (0.53 eV) > P3 (0.35 eV) at the initial stage, whereas it is O3 (0.53 eV) > P3 (0.21 eV) > P2 (0.16 eV) at a highly desodiated stage. The former can be traced back to the (NaO6) spacing, but the latter is related to the different Na sites. Our results thus provide a factor of the structural evolution and Na ion diffusion barrier by considering (NaO6) width and Na site changes during desodiation. [ABSTRACT FROM AUTHOR]

Single phase, polycrystalline perovskite oxide SrVO3, with its intrinsic low effective work function and facile synthesis process, is a promising thermionic electron emitter cathode candidate, in which previous works have shown evidence of an effective work function as low as 2.3 eV. In this work, we study the vacuum activation process of SrVO3 and find that it has promising emission stability over 15 days of continuous high temperature operation. We find that SrVO3 shows surface Sr and O segregation during its operation, which we hypothesize is needed to create a positive surface dipole, leading to a low effective work function. Emission repeatability from cyclic heating and cooling suggests the promising stability of the low effective work function surface, and additional observations of drift-free emission during 1 h of continuous emission testing at high temperature further demonstrate its excellent performance stability. This assessment of the emission stability over time and the interplay of evolving surface chemistry with emission behavior are necessary for understanding how best to prepare, process, and operate SrVO3 cathodes. [ABSTRACT FROM AUTHOR]

To cope with the shuttling of soluble lithium polysulfides in lithium–sulfur batteries, confinement tactics, such as trapping of sulfur within porous carbon structures, have been extensively studied. Although performance has improved a bit, the slow polysulfide conversion inducing fast capacity decay remains a big challenge. Herein, a NiS2/carbon (NiS2/C) composite with NiS2 nanoparticles embedded in a thin layer of carbon over the surface of micro-sized hollow structures has been prepared from Ni-metal–organic frameworks. These unique structures can physically entrap sulfur species and also influence their redox conversion kinetics. By improving the reaction kinetics of polysulfides, the NiS2/carbon@sulfur (NiS2/C@S) composite cathode with a suppressed shuttle effect shows a high columbic efficiency and decent rate performance. An initial capacity of 900 mAh g−1 at the rate of 1 C (1 C = 1675 mA g−1) and a low-capacity decline rate of 0.132% per cycle after 500 cycles are obtained, suggesting that this work provides a rational design of a sulfur cathode. [ABSTRACT FROM AUTHOR]

The Air-breathing Microwave Plasma CAThode (AMPCAT) has been developed for air-breathing electric propulsion in very-low Earth orbit. In this study, the standalone AMPCAT plasma characteristics are analyzed by means of several diagnostic tools and operation on xenon is compared to a conventional hollow cathode. A transition of AMPCAT extracted current from a lower (< 0.1 A) to higher-current (> --> 0.5 A) mode, triggered by increasing the negative cathode bias voltage, is accompanied by a significant rise in internal electron density and external electron temperature. The AMPCAT is coupled with a cylindrical Hall thruster in the 100–300 W power-level running on 0.5–0.7 mg/s of xenon, and the thrust is directly measured for cathode operation with both xenon and air. Stable thruster operation is demonstrated for the AMPCAT running on both propellants. For xenon, the performance is compared to a hollow cathode, which reveals matching discharge current profiles but a significantly higher thrust for the AMPCAT at low discharge voltages, approximately two times higher at 200 V. Langmuir probe measurements highlight a 30–40 V lower plasma potential in the cathode vicinity for the AMPCAT with xenon compared to both the hollow cathode and AMPCAT with air. This indicates a significantly improved coupling of cathode electrons to the thruster discharge, yielding an increased degree of ionization. Faraday probe and Wien filter results show that a larger current utilization efficiency drives the observed performance difference at low discharge voltages, rather than a significant change in ion acceleration or plume divergence. [ABSTRACT FROM AUTHOR]

A comprehensive physics-based modeling framework for electromigration (EM) in copper nano-interconnects is presented. It combines the three stages of stress evolution, void nucleation, and void dynamics in a single fully coupled and consolidated platform. Mechanical stress evolution, pre- and post-void nucleation, and its impact on void dynamics are deciphered, which enables accurate predictions of EM aging processes as validated by dedicated EM experiments. Subsequently, the experimentally validated model is utilized to shed light on the impact of a number of manufacturing variables, namely, line extension, via taper angle, and the effectiveness of the via bottom flux divergence point. A linear correlation between the ion leakage through the via bottom barrier and the peak tensile stress at the cathode was observed in long lines. In short lines, a blocked cathode end with atomic leakage through the anode end weakens the back-stress effect and threatens the Blech effect induced interconnect immortality. Increasing the line extension length was shown to increase the EM lifetime by about 40%. This impact was saturated beyond 1 critical dimension of line extension. On the other hand, the via taper angle increased the upstream EM lifetime by about twofold when the taper angle was increased from 0° to 30°, which indicates that the change of via taper angle has a stronger impact on EM lifetime compared to the line extension. [ABSTRACT FROM AUTHOR]

N, P co-doped MXene has been successfully demonstrated to enhance the performance of lithium-oxygen batteries. The N and P co-doping can increase interlayer distance of MXene and elevate the d-band center of Ti, thereby effectively providing more active sites, strengthening the mass transfer, optimizing the adsorption of reaction intermediates, and accelerating the deposition/decomposition of Li 2 O 2 films. [Display omitted] • N, P co-doped MXene has been successfully demonstrated to enhance the performance of lithium-oxygen batteries. • The N and P co-doping can increase interlayer distance of MXene and elevate the d-band center of Ti. • N, P co-doped MXene can effectively provide more active sites, strengthen the mass transfer, optimize the adsorption of reaction intermediates, and accelerate the deposition/decomposition of Li 2 O 2. The design and fabrication of bifunctional catalysts with high electrocatalytic activity and stability are critical for developing highly reversible Li–O 2 batteries (LOBs). Herein, the N, P co-doped MXene (NP-MXene) is prepared by one-step annealing method and evaluated as bifunctional catalyst for LOBs. The results suggest that the P doping plays a crucial role in increasing interlayer distance of MXene, thereby effectively providing more active sites, fast mass transfer, and ample space for the deposition/decomposition of Li 2 O 2. Moreover, the N doping can significantly elevate the d-band center of Ti, thereby remarkably improving the adsorption of reaction intermediates and accelerating the deposition/decomposition of Li 2 O 2 films. Consequently, the MXene-based LOBs deliver an ultrahigh specific capacity of 13,995 mAh/g at 500 mA g−1, a discharge/charge voltage gap of 0.89 V, and a cycle life up to 523 cycles with a limited capacity of 1000 mAh/g at 500 mA g−1. Impressively, the as-fabricated flexible LOBs with NP-MXene cathode display excellent cycling stability and ability to continuously power LEDs even after bending. Our findings pave the road of heteroatom doped MXenes as next-generation electrodes for high-performance energy storage and conversion systems. [ABSTRACT FROM AUTHOR]

In this work, a unique tri-metal (Co/Fe/Ni) layered double hydroxide hollow array anode catalyst (CFN-LDH/NF) and the CoP/FeNi 2 P heterojunction hollow array cathode are successfully prepared via one in-situ growth of Co-MOF on nickel foam (Co-MOF/NF) precursor, which exhibits excellent catalytic performance of OER η 1000 (CFN-LDH/NF) of 352 and 392 mV in 1.0 M KOH and alkaline seawater solution and HER η 1000 (CFNP/NF) of 281 and 312 mV in 1.0 M KOH and alkaline seawater solution. [Display omitted] The seawater electrolysis technology powered by renewable energy is recognized as the promising "green hydrogen" production method to solve serious energy and environmental problems. The lack of low-cost and ampere-level current OER (oxygen evolution reaction) and HER (hydrogen evolution reaction) catalysis limits their industrial application. In this work, a unique tri-metal (Co/Fe/Ni) layered double hydroxide hollow array anode catalyst (CFN-LDH/NF) and the CoP/FeNi 2 P heterojunction hollow array cathode are successfully prepared via one in-situ growth of Co-MOF on nickel foam (Co-MOF/NF) precursor, which exhibits excellent catalytic performance. The η 1000 values of 352 and 392 mV are achieved for CFN-LDH/NF (OER catalyst) in 1.0 M KOH and alkaline seawater solution, respectively. The CFNP/NF with a low overpotential of 281 mV is required to reach 1000 mA cm−2 current density for HER in 1.0 M KOH solution, while the η 1000 in alkaline seawater solution is 312 mV. The CFN-LDH/NF||CFNP/NF electrolyzer exhibits excellent long-term durability over 100 h, achieving current density of 500 mA cm−2 at 1.825 V in 1.0 M KOH solution. The construction of hollow tri-metal LDH and phosphides heterostructures may open a new and relatively unexplored path for fabricating high performance seawater splitting catalysis. [ABSTRACT FROM AUTHOR]

High-power pulse generators are widely used in civil and military fields. The main switch directly determines the output characteristics of the high-power pulse generators, such as the voltage front time (t f). Pseudospark switches (PSS) show a promising future for middle voltage, high repetitive frequency pulse power applications. However, how to further improve the breakdown behavior without reducing its advantages is a challenging task. In this paper, the influence of operating parameters (anode voltage U A and gas pressure p) and structural parameter (number of cathode holes) on the breakdown behavior are investigated, the related mechanism are explained, and specific improvement schemes are proposed. It is found that the t f of the single channel PSS (SCPSS) decreased significantly with increasing p, but hardly varied with U A under moderate p. However, it is not a sound solution to increase the p excessively to reduce t f. Besides, increasing the number of cathode holes can obtain a shorter t f at low pressures (which implies superior repetition frequency performance). However, at 25 Pa, the jitter (which is defined as the standard deviation of t f in multiple tests) of the 2-channel PSS is larger than that of the SCPSS. And the jitter of the 4-channel and 8-channel PSS is also greater than 6 ns and 2 ns, respectively. Through experimental and simulation analyses, it can be explained as the stepwise penetration of the virtual anode and the non-simultaneous ignition of the channels. A scheme to increase the trigger energy (ϵ) has been adopted to improve the simultaneous ignition probability, while shortening t f and reducing jitter. After optimization, the good ignition probability of the 4-channel PSS has been improved to 82% and the jitter has been reduced to less than 1 ns at 25 Pa and 14.7 mJ. [ABSTRACT FROM AUTHOR]

Herein, a heterostructured design strategy involving Ag nanoparticles (Ag NPs) stabilized with 5-(2-mercaptoethyl)tetrazole and immobilized on titania nanotubes for the oxygen reduction reaction (ORR) is reported. Bare titania nanotubular layers were annealed in air (TNT) or in a hydrogen atmosphere (hTNT), and their composites with tetrazole-stabilized Ag NPs (tz-Ag NPs) were evaluated for their ORR performance in alkaline media. The activity of the tz-Ag NP/TNT composites was shown to correlate with TNT doping level, which can be controlled by varying the annealing conditions. In all cases, the tz-Ag NP/hTNT composite shows more positive ORR onset and half-wave potentials (E1/2) than the tz-Ag NP/TNT composite. An increase in tz-Ag NP loading onto the TNT and hTNT matrix leads to a decrease in the overpotential of O2 reduction. The hTNT electrocatalyst loaded with a high amount of tz-Ag NPs (24 μg cm−2) exhibits superior ORR activity over a bare Ag electrode in terms of ORR onset and half-wave potentials. Ag NPs stabilized with tetrazole demonstrate an improved ORR performance in alkaline media compared to Ag NPs capped with citrate. The TNT electrodes loaded with tz-Ag NPs have shown high electrocatalytic activity toward the ORR indicating their suitability as cathode materials in alkaline fuel cells. [ABSTRACT FROM AUTHOR]

As an effective method to fabricate a large-area cross-sectional sample for lithium-ion battery electrodes, we perform in-plane polishing of LiNi0.8Co0.15Al0.05O2 (NCA) cathode samples and obtain a large cross-sectional area with a diameter of 1.5 mm. The polished cross-sections of NCA cathode particles are sufficiently flat to perform the atomic force microscopy (AFM) measurements on each cathode particle. Following AFM-based Kelvin probe force microscopy and scanning spreading resistance microscopy measurements, an identical in-plane polished NCA sample is assembled into a coin cell for the charge and discharge processes. After 90 charge/discharge cycles, the in-plane-polished sample is successfully disassembled from the coin cell without causing critical damage. In addition, a microcrack structure, which is a typical degradation feature of the cycles of NCA particles, is observed for the identical in-plane polished NCA sample. This indicates that the in-plane polishing method is effective for investigating identical NCA electrode samples before and after the charge/discharge process. Furthermore, the in-plane polishing method can be successfully applied to the large-area polishing of a Si-based anode which is a mixture of Si carbon complexes and graphite particles. This study presents a novel methodology for analyzing the degradation of lithium-ion battery electrode materials. [ABSTRACT FROM AUTHOR]

Fe-based perovskite without Co has a low thermal expansion coefficient and can be used as a solid oxide fuel cell (SOFC) cathode to ensure the thermal compatibility with the electrolyte; however, its further advancement is impeded by sluggish oxygen reduction reaction (ORR) dynamics. In this work, the electrospinning method and Cu doping strategy are employed to improve the microstructure and oxygen reduction kinetics of Pr 0.5 Ba 0.5 FeO 3-δ cathodes. The results show that Pr 0.5 Ba 0.5 Fe 0.8 Cu 0.2 O 3-δ has a unique fiber structure and high specific surface area, and the introduction of Cu facilitates the release of lattice oxygen, effectively increasing the oxygen vacancy content. The relaxation time distribution analysis and oxygen reduction reaction dynamics indicate that the oxygen adsorption-dissociation process is the main rate-limiting step in the oxygen reduction reaction of Pr 0.5 Ba 0.5 Fe 0.8 Cu 0.2 O 3-δ electrode materials. At 700 °C, the area-specific resistance (ASR) of the symmetric cell of Pr 0.5 Ba 0.5 Fe 0.8 Cu 0.2 O 3-δ fiber material is 0.071 Ω cm2, and the power density of the single cell reaches 988 mW cm−2, which shows good electrochemical output performance and long-term operational stability. The preparation of nanofiber cathodes with high specific surface area and porosity by electrospinning provides an effective strategy to enhance the electrocatalytic activity of the IT-SOFC cathode. [ABSTRACT FROM AUTHOR]

A major factor driving fuel cell costs is the quantity of precious metal required. Therefore, it is important to understand a timeframe where inks can be reused. In this work, we explore differences between a freshly prepared catalyst ink and one that has been stored for over a year – comparing ink properties, cathode catalyst layer microstructure, and their respective fuel cell performance. Ink studies revealed smaller agglomerate sizes and a decrease in shear viscosity for the aged ink. Longer storage time also results in fewer cracks and a more uniform ionomer distribution, as evidenced by microscopy characterization of rod-coated electrodes. Lastly, polarization curves show improved performance at higher current densities for the electrode prepared from the aged ink. We rationalize such effect in terms of enhanced ionomer adsorption onto the catalyst over time. [Display omitted] • Ball-milled inks are shelf-stable after 475 days of storage. • Ionomer adsorption onto the Pt/C surface may increase over time. • Slight MEA performance improvement for the aged ink. • Shelf stability should facilitate long-term storage of inks. [ABSTRACT FROM AUTHOR]

All-solid-state lithium-ion batteries are a promising next-generation technology because they have higher energy densities than their liquid-electrolyte counterparts. Halogen-rich argyrodite, specifically Li5.4(PS4)(S0.4Cl1.0Br0.6), was recently shown to have higher ionic conductivities compared with those of other argyrodite-like sulfides. Although the Li5.4(PS4)(S0.4Cl1.0Br0.6) in Li | Li5.4(PS4)(S0.4Cl1.0Br0.6) | Li(Ni0.8Co0.1Mn0.1)O2–Li5.4(PS4)(S0.4Cl1.0Br0.6) batteries have shown good electrochemical stability, the low discharge capacity limits the application of the battery. In continuation, this study examined the potential of a carbon additive for altering the electronic conductivity of the cathode and enhancing the capacity of Li | Li5.4(PS4)(S0.4Cl1.0Br0.6) | Li(Ni0.8Co0.1Mn0.1)O2–Li5.4(PS4)(S0.4Cl1.0Br0.6) batteries. After a 50-cycle charge/discharge, the carbon additive (0.1 C) enhanced the discharge capacity from 3.1 to 167 mAh/g, resulted in a capacity retention rate and coulombic efficiency of 95.4% and 99.9% when using 0.1 C and 0.5 C, respectively, and increased the resistance of the battery from 53 to 56 Ω. Therefore, the all-solid-state battery employing high-ion-conductive Li5.4(PS4)(S0.4Cl1.0Br0.6) and a carbon-modified cathode showed improved capacity. This study provides a proven framework for developing all-solid-state batteries employing halogen-rich argyrodite (Li7-α(PS4)(S2-αXα); α > 1) with enhanced ionic conductivities. [ABSTRACT FROM AUTHOR]

In this study, an innovative hybrid process was proposed and examined as an alternative for nickel/cobalt separation from a synthetic pregnant leach solution. The first step was carried out by employing electrodeionization of a feed solution containing 950 ppm of nickel and 100 ppm of cobalt after adding EDTA to form (Ni-EDTA)−2 complex to suppress migration of nickel cations toward cathodic compartment. This process increased nickel percentage from 90.47 to 97 in the diluted feed solution. This solution was then subjected to cation exchanging process to adsorb the remaining cobalt cations, leading to a nickel purity of 99.7 wt% with an overall recovery 71.1%. On the other hand, the cathode rinse solution of EDI process which contained a major portion of the cobalt cations underwent three stages of extraction process using cyanex 272, resulting in recovery of 65.5 wt% of cobalt with a purity of 100%. It was seen that six stages of solvent extraction process were needed to reach the same purity of cobalt cations by the traditional extraction method. These findings highlight the superior performance of the proposed hybrid process, which not only yielded a relatively high recovery ratio but also ensured excellent purity of nickel and cobalt. [ABSTRACT FROM AUTHOR]

The Co/Co-Nx-embedded mesoporous 3D flower-like carbon sheet (Co/Co-N-MC-800) catalyst is successfully prepared from high N content H-1,2,4-Triazol-3-amine organic-ligand at different pyrolysis temperatures based on in situ pyrolysis Co-metal organic frame (MOF) (Co-PTA-MOF) precursor under nitrogen. The metal active center of the mesoporous Co/Co-N-MC-800 catalyst with more defect sites is situated in the positively charged 0 ~ + 2, and the bond spacing is consistent with the Co-N4 plane structure of the co-porphyrin. The obtained Co/Co-N-MC-800 possesses an excellent oxygen reduction reaction performance with a higher onset potential (0.92 V vs RHE) and half-wave potential (0.76 V vs RHE), which is closer to Pt/C and outstanding long-term stability with 89.1% current retention after 89 h and displays an optional power density of 1079.3 ± 22.5mW·m−2 in air-breath cathode microbial fuel cell (MFC). The improved catalytic performance maybe attributes to combination of the special 3D nanostructure, embedded cobalt nanoparticles (forming Co-Nx) and N-doped mesoporous carbon sheet material. The present study provides the technical and theoretical basis for the ORR through the cathode modification of MOF prepared from non-precious metal and N content organic-ligand. [ABSTRACT FROM AUTHOR]

This study examines and compares the impact of various interfacial modification strategies in optimizing the contact resistance between the rigid ceramic electrolyte and cathode active material (AM) in solid‐state sodium‐ion batteries (SSBs). All the cells are fabricated using Na3.1V2P2.9Si0.1O12, Na3.456Mg0.128Zr1.872Si2.2P0.8O12, and Na as a cathode AM, solid electrolyte (SE) and anode, respectively. The AM/SE interface is modified by (1) wetting the interface with organic liquid electrolyte (LE), (2) slurry casting and sintering a thin layer of composite cathode, and (3) infiltrating AM precursors inside the porous SE structure followed by drying and sintering. Despite exhibiting a stable cyclability performance, the SSBs prepared using the LE modification and composite cathode approach possess a low AM loading of < 1 mg·cm−2. On the other hand, the SSBs with infiltrated‐cathode exhibit a superior discharge capacity of ∼ 102 mAh·g−1 at 0.2C and less than 5% capacity fading after 50 cycles at room temperature. Notably, these cells contain a high AM loading of 2.12 mg·cm−2. The microstructural analysis reveals the presence of AM particles inside the pores of the porous SE, allowing for the efficient insertion/removal of sodium ions. The porous scaffold of SE not only provides continuous sodium‐ion conduction pathways inside the cathode structure but also renders stability by accommodating stress induced by volume change during repeated cycling. The outcomes of this work demonstrate the effectiveness of the wet‐chemical infiltration technique in improving the AM loading and storage capacity performance of SSBs working at 25°C. [ABSTRACT FROM AUTHOR]

Bipolar plates perform multiple functions for the proton exchange membrane fuel cell (PEMFC). This study focuses on optimizing cathode channels to leverage a local loss mechanism to enhance gas transfer and diffusion efficiency. Through the investigation of 3D simulations, this research delves into the effects of curvature of cathode channels on both reactant transfer and diffusion. The results illustrated that compared with straight channels, the cell performance improves as the bending angle (θ) of 2.5° and 5° at different current densities. Specifically, at a bending angle of 5°, a 5.5% higher current density than the channel of 0° is obtained. This suggests that moderate curvature can effectively promote efficient mass transport and diffusion, ultimately contributing to enhanced cell performance. Furthermore, the analysis of local mass transfer and diffusion around the bends of channels underscores the importance of the balance between these factors. While bending angles within the range of 2.5° to 5° offer optimal performance gains, excessive curvature, such as a 10° angle, may lead to diminished cell performance. By identifying the optimal bending angle range and elucidating the underlying mechanisms driving performance improvements, this study provides insights into the design and optimization of cathode flow fields in AO-PEMFC. [ABSTRACT FROM AUTHOR]

The refabrication of lithium-ion batteries (LIBs) from the value-added metals of spent LIBs is a promising strategy to mitigate current environmental and resource availability issues. However, the preparation of high-performance LiCoO2 (LCO) by the closed-loop reutilization of LCO resources remains challenging. This study proposes a novel recycling strategy that involves separating Li and Co from spent LIBs in a single step, followed by the closed-loop refabrication of LCO cathode materials using the regenerated resources with Ti doping and multi-stage calcination. The results showed that 99.5 pct of the Li was leached, and Co was recovered as a precipitated complex (Co3O4 precursor) in an environmentally friendly tartaric acid/H2O2 medium under the optimized leaching conditions. The leaching behavior of Li conformed to the Avrami equation model, and the associated activation energy was calculated to be 21.98 kJ/mol at temperatures of 313–353 K. The discharge capacity of the regenerated LCO (R-LCO) subjected to two-stage calcination (204.39 mAh/g) was significantly higher than that of the LCO subjected to one-stage calcination (187.11 mAh/g) at 0.1 C in the voltage range of 3.0–4.58 V. Ti doping was found to have little effect on the structure and morphology of the regenerated Co3O4, although it imparted R-LCO with a higher crystallinity and superior cycling performance. The LCO with Ti doping (Ti/Co molar ratio = 0.005:1) synthesized via two-stage calcination exhibited an initial coulombic efficiency of 93.65 pct and maintained a capacity retention of 93.8 pct after the 50th cycle. This work provides a promising method for resynthesizing high-performance cathode materials via the closed-loop recovery of spent LIB materials. [ABSTRACT FROM AUTHOR]

The internal water content of the proton exchange membrane fuel cell (PEMFC) stack significantly affects its performance and duration. To achieve optimal humidity level, real-time monitoring of the humidity of the cathode and the anode is crucial for the PEMFC. As far as we know, the relative humidity of the PEMFC can be estimated via an observer based on the measurable output voltage. However, the rapid changes in vehicle operating conditions pose a challenge to the estimation accuracy. Different from the existing sliding mode observers (SMOs), this study pays more attention to the testing noise of voltage measuring sensor. To reduce the noise influence and improve the estimation accuracy, a new sliding mode observer (NSMO) combined with an online Kalman filter is presented based on the dimensionless model of the PEMFC in this study. The applicability of the proposed NSMO in estimating the cathode relative humidity and the anode relative humidity is illustrated by the simulation results. At the same time, comparisons between the NSMO and the online Kalman filter are provided which show a substantially higher estimation accuracy and lower cost for the NSMO. Furthermore, the final results indicate the mean absolute deviations of the cathode and the anode relative humidity for the NSMO are, respectively, reduced to 0.39% and 0.28%. [ABSTRACT FROM AUTHOR]

Anisotropic volume changes in primary particles of layered Ni‐rich transition metal oxides generate mechanical stresses during electrochemical cycling. This results in structural degradation and side reactions that deteriorate battery performance. To address this issue, a cross‐linked epoxy natural rubber (CENR) is employed as the protective elastomeric interphase. The viscoelastic properties of CENR facilitated a strong adhesion to the surface of Ni‐rich cathodes, thereby helping alleviate mechanical stresses during cycling. This approach maintained the structural integrity of the Ni‐rich cathodes and suppressed detrimental interfacial reactions. Consequently, the fortified Ni‐rich cathode retained 95.9% of its capacity after 300 cycles at 0.5 C and 82.8% after 500 cycles at 1 C. This study highlights the essential role of elastomeric materials in stabilizing Ni‐rich cathodes and offers insights that can enable the development of additional protective elastomeric layers for battery electrode materials. [ABSTRACT FROM AUTHOR]

P‐type organic cathode materials typically exhibit high redox potentials and fast redox kinetics, presenting broad application prospects in aqueous zinc batteries (AZBs). However, most of the reported p‐type organic cathode materials exhibit limited capacity (<100 mAh g−1), which is attributable to the low mass content ratio of oxidation‐reduction active functional groups in these materials. Herein, we report a high‐capacity p‐type organic material, 5,12‐dihydro‐5,6,11,12‐tetraazatetracene (DHTAT), for aqueous zinc batteries. Both experiments and calculation indicate the charge storage of DHTAT mainly involves the adsorption/desorption of ClO4− on the −NH− group. Benefitting from the high mass content ratio of the −NH− group in DHATA molecule, the DHATA electrode demonstrates a remarkable capacity of 224 mAh g−1 at a current density of 50 mA g−1 with a stable voltage of 1.12 V. Notably, after 5000 cycles at a high current density of 5 A g−1, DHTAT retains 73 % of its initial capacity, showing a promising cycling stability. In addition, DHTAT also has good low‐temperature performance and can stably cycle at −40 °C for 4000 cycles at 1 A g−1, making it a competitive candidates cathode material for low‐temperature batteries. [ABSTRACT FROM AUTHOR]

Realizing high‐rate and high‐capacity features of Lihium‐organic batteries is essential for their practical use but remains a big challenge, which is due to the instrinsic poor conductivity, limited redox kinetics and low utility of organic electrode mateials. This work presents a well‐designed donor‐acceptor Covalent Organic Framework (COFs) with extended conjugation, mesoscale porosity, and dual redox‐active centers to promote fast charge transfer and multi‐electron processes. As anticipated, the prepared cathode with benzo [1,2‐b:3,4‐b′:5,6‐b′′] trithiophene (BTT) as p‐type and pyrene‐4,5,9,10‐tetraone (PTO) as n‐type material (BTT‐PTO‐COF) delivers impressive specific capacity (218 mAh g−1 at 0.2 A g−1 in ether‐based electrolyte and 275 mAh g−1 at 0.2 A g−1 in carbonate‐based electrolyte) and outstanding rate capability (79 mAh g−1 at 50 A g−1 in ether‐based electrolyte and 124 mAh g−1 at 10 A g−1 in carbonate‐based electrolyte). In addition, the potential of BTT‐PTO‐COF electrode for prototype batteries has been demonstrated by full cells of dual‐ion (FDIBs), which attain comparable electrochemical performances to the half cells. Moreover, mechanism studies combining ex situ characterization and theoratical calculations reveal the efficient dual‐ion storage process and facile charge transfer of BTT‐PTO‐COF. This work not only expands the diversity of redox‐active COFs but also provide concept of structure design for high‐rate and high‐capacity organic electrodes. [ABSTRACT FROM AUTHOR]

Solid‐state batteries with lithium‐metal anodes have emerged as a promising alternative to traditional lithium‐ion batteries thanks to their enhanced energy density and safety. However, the integration of solid‐state electrolytes is still hindered by mechanical instabilities caused by the rigid nature of the system. Stress and strain can be transferred at the interface between electrodes and solid electrolyte, inducing material damage during cycling. To address this issue, a comprehensive understanding of the interplay between electrochemical reactions and mechanical effects is crucial. In this article, a critical review of various approaches to model the multiphysics behavior of Li‐metal solid‐state batteries is provided by analyzing their advancements and limitations. The focus lies on workflows which simulate the effect of microstructural and material property changes on the degradation processes. Continuum modeling of three key chemo‐mechanical challenges is explored: dendritic growth from Li‐metal anodes, structural instability in composite cathodes, and solid electrolyte degradation caused by the formation of unstable interphases. The conclusion highlights the existing challenges and upcoming trends in multiphysics and microscale modeling of batteries. [ABSTRACT FROM AUTHOR]

The cathodic catalytic activity for the oxygen reduction reaction (ORR) plays a critical role in determining the performance of proton-conducting solid oxide fuel cells (P-SOFCs). BaCo 0.4 Fe 0.4 Zr 0.2 O 3-δ (BCFZ) has emerged as a promising cathode for P-SOFCs due to its triple-phase conductivity. Nevertheless, its suboptimal proton conductivity and hydration ability at intermediate temperatures prevent it from achieving the anticipated ORR catalytic activity. To address these limitations, this study explores the enhancement of electrocatalytic activity in BCFZ through alkali metal doping and A-site defect construction. The effects of such modifications on oxygen surface exchange kinetics and ORR catalytic activity are systematically investigated. The findings reveal that BCFZ exhibits relatively low parameters in terms of electronic conductivity, oxygen ion conductivity, oxygen vacancy concentration, k chem , and D chem. Conversely, these parameters are markedly improved in A-site deficient BCFZ (D-BCFZ) and Na/K-doped BCFZ. Consequently, the enhancement of these properties yields a significant increase in ORR catalytic activity, with D-BCFZ demonstrating the best electrochemical performance. Specifically, P-SOFC with D-BCFZ cathode achieves an R p value of just 0.073 Ω cm2 and a P max value of 0.928 W cm−2 at 650 °C. This study provides theoretical insight into the mechanisms by how alkali metal doping and defect construction enhance the ORR catalytic activity of BCFZ. These findings offer valuable guidance for the development and optimization of high-performance P-SOFC cathodes. [ABSTRACT FROM AUTHOR]

Sm 0.5 Sr 0.5 CoO 3-δ (SSC) fiber-electrode materials were prepared via electrospinning in this work. The characteristics of SSC fibers are influenced by the parameters of electrospinning, specifically the nitrate concentration of the spinning solution, applied voltage, and the gap between the spinneret and collector. The as-prepared SSC fibers exhibited average diameters ranging from 240 nm to 6.49 μm, which contracted to 50 nm–2.53 μm after calcination at 800 °C. Symmetric cells with SSC fiber-electrodes demonstrated an area-specific resistance (ASR) ranging from 0.212 to 0.508 Ω cm2 at 700 °C in air. In addition to the morphology of SSC fibers, the average grain size of the SSC fibers also exhibited potential influence on their ASR performance. [ABSTRACT FROM AUTHOR]

The LiFe 0.6 Mn 0.4 PO 4 /C composite has become a cost-effective and reliable material for lithium battery storage in commercial applications, due to its significant safety benefits. However, its industrial application is limited by its suboptimal high-rate capacity and unsatisfactory cycling performance. To address this issue, Li(Fe 0.6 Mn 0.4) 1-x Sb x PO 4 (x = 0, 0.01, 0.03, 0.04, 0.05) materials were synthesized using a one-step solvothermal method in this study, aiming to modulate the microstructure and achieve Sb doping, thereby enhancing the electrochemical performance. The electrochemical test results indicate that LFMP/C doped with Sb (designated as LFMP/C-Sb0.04) displays exceptional electrochemical performance, with remarkable capacities of 166.6 mAh·g−1 and 146.8 mAh·g−1 at 0.2C and 1C, respectively. Notably, it achieves a capacity of 126.1 mAh·g−1 at a high rate (5C) and maintains an impressive capacity retention rate of 93.6 % after 300 cycles, outperforming the original LMFP/C (109.5 mAh·g−1), which retains only 61.5 % of its initial capacity. Further characterization of the samples reveals that in situ Sb doping promotes the growth of the [001] crystal orientation, enhancing the lithium-ion diffusion rate and effectively reducing electrode polarization and charge transfer resistance, thereby contributing to its exceptional rate performance. Moreover, Sb doping increases the M − O binding energy, strengthens the metal-oxygen framework, mitigates the Jahn-Teller effect caused by Mn3+ dissolution, and enhances its cycling stability. [Display omitted] [ABSTRACT FROM AUTHOR]

Perovskite oxide Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3‒δ (BSCF) is a highly active cathode material widely studied for intermediate temperature solid oxide fuel cells (IT-SOFCs), however, the tendency of phase transition of BSCF under IT-SOFC operating conditions poses a critical challenge for its reliable applications. Here, a multiphase BSCF-Gd 0.1 Ce 0.9 O 1.95 (GDC) nanocomposite with heterogeneous interfaces is synthesized at a relatively low calcination temperature of 750 °C. Both the multiphase composition and microstructural morphology of the nanocomposite are very stable during annealing at 750 °C. The unique multiphase structure and ultrafine microstructure of the nanocomposite can be maintained in the resultant cathode through a sintering-free direct assembly fabrication method. As a consequence, a corresponding single cell based on the BSCF-GDC nanocomposite cathode generates a maximum power density of 1.41 W cm−2 at 750 °C with outstanding galvanostatic stability for 100 h. This work provides an effective means for the design and utilization of highly active BSCF-based nanocomposite cathodes for durable IT-SOFCs. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries have drawn worldwide attention as ideal candidates for the upcoming generation of large‐scale electrical energy storage devices due to the low cost and abundance of sodium. Due to its unique electrochemical and chemical properties, sodium‐ion batteries hold the promise of breaking geographical and environmental constraints, achieving efficient sodium storage under low‐temperature conditions. However, low‐temperature sodium‐ion batteries, especially for their electrode materials, still face numerous challenges, such as the sluggish electrochemical reaction kinetics, poor material stability, significant volume changes leading to the pulverization of materials and the rapid degradation of battery performance. Here, it is focused on the modification methods for electrode materials, the research progress on cathode and anode materials of low‐temperature sodium‐ion batteries is summarized systematically and the other components of the electrodes are discussed briefly, and the shortcomings of the current research and possible future research directions are discussed thoroughly. [ABSTRACT FROM AUTHOR]

Achieving both high iodine loading cathode and high Zn anode depth of discharge (DOD) is pivotal to unlocking the full potential of energy‐dense Zn‐I2 batteries. However, this combination exacerbates the detrimental shuttle effect of polyiodide intermediates, significantly impairing the battery's reversibility and stability. Herein, this study reports an advanced high‐loading iodine cathode (denoted as MX‐AB@I) enabled by a multifunctional Ti3C2Tx MXene modulator, which presents high stability and energy density in Zn‐I2 batteries. Through comprehensive experimental and theoretical analyses, the intrinsic regulating mechanisms are elucidated by which the MXene modulator effectively suppresses polyiodide shuttling, enhances iodine conversion kinetics, and dramatically improves Zn anode reversibility. With the aid of the MXene modulator, the MX‐AB@I composite cathode achieves a high iodine mass loading of 23 mg cm−2 and realizes a practically high areal capacity of 4.0 mAh cm−2. When paired with a thin Zn anode (10 µm), this configuration realizes a high Zn DOD of 78.7% and a high energy density of 171.3 Wh kg−1, surpassing the majority of Zn‐I2 battery systems reported in the literature. This study presents an effective approach to designing high‐loading iodine cathodes for Zn‐I2 batteries by leveraging MXene modulators to regulate critical electrochemical reaction processes. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) hold great promise for rechargeable batteries. However, the synthesis of COFs with abundant active sites, excellent stability, and increased conductivity remains a challenge. Here, chemically stable fully sp2 carbon‐conjugated COFs (sp2c‐COFs) with multiple active sites are designed by the polymerization of benzo[1,2‐b:3,4‐b′:5,6‐b′′]trithiophene‐2,5,8‐tricarbaldehyde) (BTT) and s‐indacene‐1,3,5,7(2H,6H)‐tetrone (ICTO) (denoted as BTT‐ICTO). The morphology and structure of the COF are precisely regulated from "butterfly‐shaped" to "cable‐like" through an in situ controllable growth strategy, significantly promoting the exposure and utilization of active sites. When the unique "cable‐like" BTT‐ICTO@CNT is employed as lithium‐ion batteries (LIBs) cathode, it exhibits exceptional capacity (396 mAh g−1 at 0.1 A g−1 with 97.9 % active sites utilization rate), superb rate capacity (227 mAh g−1 at 5.0 A g−1), and excellent cycling performance (184 mAh g−1 over 8000 cycles at 2.0 A g−1 with 0.00365 % decay rate per cycle). The lithium storage mechanism of BTT‐ICTO is exhaustively revealed by in situ Fourier transform infrared, in situ Raman, and density functional theory calculations. This work provides in‐depth insights into fully sp2c‐COFs with multiple active sites for high‐performance LIBs. [ABSTRACT FROM AUTHOR]

Activating anionic redox reaction (ARR) has attracted a great interest in Li/Na‐ion batteries owing to the fascinating extra‐capacity at high operating voltages. However, ARR has rarely been reported in aqueous zinc‐ion batteries (AZIBs) and its possibility in the popular MnO2‐based cathodes has not been explored. Herein, the novel manganese deficient MnO2 micro‐nano spheres with interlayer "Ca2+‐pillars" (CaMnO‐140) are prepared via a low‐temperature (140 °C) hydrothermal method, where the Mn vacancies can trigger ARR by creating non‐bonding O 2p states, the pre‐intercalated Ca2+ can reinforce the layered structure and suppress the lattice oxygen release by forming Ca−O configurations. The tailored CaMnO‐140 cathode demonstrates an unprecedentedly high rate capability (485.4 mAh g−1 at 0.1 A g−1 with 154.5 mAh g−1 at 10 A g−1) and a marvelous long‐term cycling durability (90.6 % capacity retention over 5000 cycles) in AZIBs. The reversible oxygen redox chemistry accompanied by CF3SO3− (from the electrolyte) uptake/release, and the manganese redox accompanied by H+/Zn2+ co‐insertion/extraction, are elucidated by advanced synchrotron characterizations and theoretical computations. Finally, pouch‐type CaMnO‐140//Zn batteries manifest bright application prospects with high energy, long life, wide‐temperature adaptability, and high operating safety. This study provides new perspectives for developing high‐energy cathodes for AZIBs by initiating anionic redox chemistry. [ABSTRACT FROM AUTHOR]

A generalized inductively coupled plasma (ICP) efficiency model is derived, which may be used to predict plasma generation efficiency with many types of radio frequency (RF) electric propulsion system. The analytical ICP discharge model is used to examine device scaling, and investigate trends in ICP performance as a function of geometry and system inputs. The ICP efficiency model is applied to an analytical RF cathode model to predict device behavior. Results from the updated RF cathode model show improvements in agreement with experimental data. [ABSTRACT FROM AUTHOR]

Sodium sulfide (Na2S) as an initial cathode material in room-temperature sodium-sulfur batteries is conducive to get rid of the dependence on Na-metal anode. However, the micron-sized Na2S that accords with the practical requirements is obstructed due to poor kinetics and severe shuttle effect. Herein, a subtle strategy is proposed via regulating Na2S redeposition behaviours. By the synergistic effect from both conductive structure and cuprous sulfide (Cu2S) catalysis, the micron-sized Na2S particles are broken down and redeposited to nano-size during the initial cycle which can be fully utilized in subsequent cycles. Consequently, the Na2S/CPVP@Cu2S||Na cell delivers excellent cyclability (670 mAh gS−1 after 500 cycles) with a remarkable average Coulombic efficiency over 99.7% and rate capability (480 mAh gS−1 at 4 A gS−1). Besides, the Na-free anodes are used to prove the application prospects. This work provides an innovative idea for utilizing micron-sized Na2S and offers insights into its conversion pathway. Authors report that micron-sized Na2S particles can be self-refinement into nanoparticles during the initial cycle under rapid solid-liquid-solid conversion, which facilitates the development of Na-free anode systems in room-temperature sodium-sulfur batteries. [ABSTRACT FROM AUTHOR]

Structure deterioration and side reaction, which originated from the solvated H2O, are the main constraints for the practical deployment of both cathode and anode in aqueous Zn-ion batteries. Here we formulate a weakly solvating electrolyte to reduce the solvating power of H2O and strengthen the coordination competitiveness of SO42− to Zn2+ over H2O. Experiment results and theoretical simulations demonstrate that the water-poor solvation structure of Zn2+ is achieved, which can (i) substantially eliminate solvated-H2O-mediated undesirable side reactions on the Zn anode. (ii) boost the desolvation kinetics of Zn2+ and suppress Zn dendrite growth as well as structure aberration of the cathode. Remarkably, the synergy of these two factors enables long-life full cells including Zn/NaV3O8·1.5H2O, Zn/MnO2 and Zn/CoFe(CN)6 cells. More importantly, practical rechargeable AA-type Zn/NVO cells are assembled, which present a capacity of 101.7 mAh and stability of 96.1% capacity retention after 30 cycles at 0.66 C. The practical deployment of aqueous zinc-ion batteries is hindered by the structure deterioration and side reactions at electrodes. Here, the authors introduce a weakly solvating electrolyte with butanone as an electrolyte additive to stabilize both the cathode and anode of aqueous zinc-ion batteries simultaneously. [ABSTRACT FROM AUTHOR]

Cobalt‐free LiNi0.5Mn1.5O4 (LNMO) is a promising cathode material for high‐energy and power‐density lithium‐ion batteries (LIBs). However, its commercial adoption is hindered by rapid capacity degradation due to the unstable LNMO/electrolyte interface caused by LNMO's high operating voltage. Structural degradation from Jahn–Teller distortion and metal‐ion dissolution also contributes to poor cycling stability. Additionally, producing industrial‐grade LNMO with high tap density, low surface area and reduced metal‐ion dissolution is challenging. This study addresses these challenges through a rational material design approach, synthesizing LNMO with large spherical secondary particles (>14.0 µm) and high tap density (>2.0 g cm−3). The primary particles (1.5–6.0 µm) exhibit a truncated‐octahedral shaped morphology that predominantly exposes (111) surface facets, with fewer (100) surfaces, stabilizing the LNMO/electrolyte interface, reducing metal dissolution, and enhancing lithium‐ion kinetics. Silicon infusion into grain boundaries further improves structural integrity by forming a silicon‐rich phase. The tailored LNMO demonstrates exceptional rate capability, cycling stability, and improved interfacial kinetics, significantly advancing the potential for cobalt‐free LNMO in high‐voltage LIBs. This work highlights the importance of tailored cathode material design for achieving the performance and stability required for emerging high‐voltage LIBs applications. [ABSTRACT FROM AUTHOR]

Manganese‐based cathode materials have garnered extensive interest because of their high capacity, superior energy density, and tunable crystal structures. Despite their cost‐effectiveness, challenges like Mn dissolution and gas evolution originating from the irreversible structural degradation pose risks to stability and prolonged electrochemical behaviors, ultimately constraining their practical applications and market prospects. While the material characteristics and redox mechanisms of Mn‐based cathodes are extensively investigated, a systematic iterative approach to material design that balances performance and application demands remains both necessary and urgent. Recent strategies for enhancing cathode performances emphasize the innovative introduction and customization of composite structures in Mn‐based cathode materials to address the challenges above. This review aims to provide a comprehensive understanding of composite‐structure construction methodologies and offers practical guidelines for effectively designing high‐stability Mn‐based composite‐structure cathode materials. This encompasses the classifications of composite scales, the discussions for the extent of composite‐structure construction inside and outside of the cathode grains, and an exploration of the development potential of these materials, especially for grid‐scale applications. [ABSTRACT FROM AUTHOR]

Layered iron (Fe) ‐based fluorophosphates, Na2FePO4F (NFPF) stands for a cost‐effective and voltage‐advantageous cathode material for sodium‐ion batteries. Nevertheless, the lack of stability imposes constraints on its development and the decay mechanism remains shrouded in ambiguity. Herein, this work proposes the breakup of Fe─F bond in octahedral dimer accountable for the dissolution of redox centers and the formation of electrochemically inert phase, ultimately leading to the deterioration of electrochemical stability. To verify and address this, Boron (B) atoms situated in interstitial positions of PO4 tetrahedra appearing trigonal BO3 can be specifically targeted to enhance bond covalency and tailor electronic rearrangements at Fe─F bonds, thus stabilizing the octahedral dimer structure. This also facilitates rapid Na+ diffusion dynamics and accelerated electronic conductivity. As expected, NFPF‐B exhibits an ultra‐high discharge specific capacity (118.34 mAh g−1 at 0.1C) and excellent long‐term durability (capacity retention of 91.9% after 1000 cycles). The stability of the octahedra dimer is underscored by minimal volume change (2.9%) within the two‐stage biphase reaction of sodium storage mechanism. This work elucidates the enduring degradation mechanism of NFPF from octahedral dimers and offer theoretical guidance for Fe‐based cathode materials with prolonged stability. [ABSTRACT FROM AUTHOR]

This work delineates the thermal safety of full-scale sodium-ion batteries (SIBs) by interrogating the material-level electrochemical and thermal responses of micro and nano-structured tin (Sn) based anodes and sodium vanadium phosphate (NVP) cathodes in suitable electrolyte systems. Informed by these material-level signatures, we delineate cell-level thermal safety maps cognizant of underlying electrode–electrolyte interactions in SIBs. [ABSTRACT FROM AUTHOR]

The search for suitable electrode materials for sodium storage in sodium-ion batteries (SIBs) poses significant challenges. Na0.44MnO2 (NMO) has emerged as a promising candidate among various cathode materials due to its distinct three-dimensional tunnel structure, which facilitates Na+ diffusion and governs structural stress fluctuations during Na+ intercalation/deintercalation. However, NMO faces obstacles such as limited electronic conductivity, lattice distortion induced by the Jahn–Teller effect of Mn3+ during cycling, and Mn3+ disproportionation leading to material dissolution, which affects cycling durability. To overcome these problems, Na0.44MnO2/polypyrrole (NMO/PPy) composites were fabricated through surface modification of the conductive PPy using an ultrasonically assisted dispersion method. Experimental results show that NMO/PPy with a 7 wt% PPy content exhibits superior sodium storage capabilities. Specifically, at a current density of 0.5C, the initial specific discharge capacity reaches 135.2 mA h g−1, a 12.1% increase over pristine NMO, with a capacity retention of 94.5% after 100 cycles. Of particular note is a capacity retention of 82% after 500 cycles at 1C, attributed to the PPy coating, which suppresses Mn3+ side reactions, enhances the structural stability and electronic conductivity of NMO, and accelerates Na+ diffusion. These results suggest that the use of conductive polymer coatings represents a simple and effective strategy to improve the sodium storage capacity of NMO, paving the way for the further development of high-performance SIB cathodes. [ABSTRACT FROM AUTHOR]

[Display omitted] The interlayer distances in layered electrode materials, influenced by the chemical composition of the confined interlayer regions, have a significant impact on their electrochemical performance. Chemical preintercalation of inorganic metal ions affects the interlayer spacing, yet expansion is limited by the hydrated ion radii. Herein, we demonstrate that using varying concentrations of decyltrimethylammonium (DTA+) and cetyltrimethylammonium (CTA+) cations in chemical preintercalation synthesis followed by hydrothermal treatment, the interlayer distance of hybrid bilayered vanadium oxides (BVOs) can be tuned between 11.1 Å and 35.6 Å. Our analyses reveal that these variations in interlayer spacing are due to different amounts of structural water and alkylammonium cations confined within the interlayer regions. Increased concentrations of alkylammonium cations not only expand the interlayer spacing but also induce local bending and disordering of the V-O bilayers. Electrochemical cycling of hybrid BVO electrodes in non-aqueous lithium-ion cells show that specific capacities decrease as interlayer regions expand, suggesting that the densely packed alkylammonium cations obstruct intercalation sites and hinder Li+ ion transport. Furthermore, we found that greater layer separation facilitates the dissolution of active material into the electrolyte, resulting in rapid capacity decay during extended cycling. This study emphasizes that layered electrode materials require both spacious interlayer regions as well as high structural and chemical stabilities, providing guidelines for structural engineering of organic–inorganic hybrids. [ABSTRACT FROM AUTHOR]