Local Charge Research Articles

Enhanced Electromagnetic Energy Conversion in an Entropy‐driven Dual‐magnetic System for Superior Electromagnetic Wave Absorption

AbstractThermochemical conversion is a highly effective method for upgrading organic solid wastes into high‐value materials, contributing to carbon neutrality and peak, carbon emission goals. It also serves as a pathway to develop energy‐efficient electromagnetic wave absorbing (EMWA) materials. In this study, fish skin to successfully in situ nitrify Prussian Blue into Fe3N under external thermal driving condition, resulting in high saturation magnetization is utilized. The resulting Fe3N@C demonstrates outstanding EMWA property, achieving a minimum reflection loss of −71.3 dB. Furthermore, by introducing cellulose nanofiber, a portion of the iron nitride is transformed into iron carbide, resulting in Fe3C/Fe3N@C. This composite exhibits enhanced EMWA properties owing to wider local charge redistribution and stronger electronic interactions, achieving an effective absorption bandwidth (EAB) of 6.64 GHz. Electromagnetic simulations and first‐principles calculations further elucidate the EMWA mechanism, and the maximum reduction value of the radar‐cross section reached 37.34 dB·m2. The design of multilayer gradient metamaterials demonstrated an ultra‐broadband EAB of 11.78 GHz. This paper presents an efficient strategy for atomic‐level biomass waste utilization to prepare Fe3N, provides novel insights into the conversion between metal nitrides and metal carbides, and offers a promising direction for the development of advanced EMWA materials.

Dynamic Adaptive Charging Network Planning Under Deep Uncertainties

Charging infrastructure is the backbone of electromobility. Due to new charging behaviors and power distribution and charging space constraints, the energy demand and supply patterns of electromobility and the locations of current refueling stations are misaligned. Infrastructure developers (charging point operators, fleet operators, grid operators, vehicle manufacturers, and real-estate developers) need new methodologies and tools that help reduce the cost and risk of investments. To this extent we propose a transport-energy-demand-centric, dynamic adaptive planning approach and a data-driven Spatial Decision Support System (SDSS). In the SDSS, with the help of a realistic digital twin of an electrified road transport system, infrastructure developers can quickly and accurately estimate key performance measures (e.g., charging demand, Battery Electric Vehicle (BEV) enablement) of a candidate charging location or a network of locations under user-specified transport electrification scenarios and constraints and interactively and continuously calibrate and/or expand their network plans as facts about the deep uncertainties about the supply side of transport electrification (i.e., access to grid capacity and real-estate and presence of competition) are gradually discovered/observed. This paper describes the components and the planning support of the SDSS and how these can be used in competitive and collaborative settings. Qualitative user evaluations of the SDSS with 33 stakeholder organizations in commercial discussions and pilots have shown that both transport-energy-demand-centric and dynamic adaptive planning of charging infrastructure planning are useful.

Analyzing the influence of electric vehicle charging scheduling on distribution transformer lifespan

The ongoing growth in global electricity demand and rapid proliferation of electric vehicles (EVs) are posing challenges to the operation of the low voltage power networks and their components. This study aims to analyze the impacts of peak-load demand on the distribution transformers, considering mild and extreme combinations of electric energy demand and localized charging of plug-in EVs under their different penetration levels, hypothesizing that shifting the demand for charging throughout the day can reduce the aging of distribution transformers. The proposed method employs a fuzzy-logic-based tool, which incorporates the influence of ambient temperature, higher harmonics, reactive power compensation, reverse power flows, and overload. Three different charging/discharging modes have been considered: demand charging, off-peak charging, and synergy of off-peak charging and vehicle-to-house technology. The results indicate that off-peak charging emerges as 2.1 times more effective than demand charging in terms of the transformer's loss of life, particularly for ultimate EV penetration of 100 %. It is demonstrated that the utilization of charging scheduling for EVs should be prioritized to defer costly system upgrades and reinforcements, particularly when EV penetration exceeds 50 %.

Boosting Photoluminescence of Rare-Earth-Based Double Perovskites by Isoelectronic Doping of ns2 Metal Ions.

Doping of ns2 metal ions as an energy transfer (ET) bridge can significantly elevate the photoluminescence properties. Nonetheless, the fundamental influence of ns2 metal ions on the local lattice structures remains unclear, hindering the advancement of functional materials. Herein, Sb3+ doped rare earth double perovskites is employed as a typical case to demonstrate this issue. It is found that the isoelectronic doping of Sb3+ ions not only enhances the ET efficiency but also changes their localized electronic and lattice structures. Both density functional theory (DFT) and Judd-Ofelt (J-O) theory calculations provide unambiguous evidence that the isoelectronic doping of Sb3+ ions enables a more localized charge density in the [LnCl6]3- (Ln: Lanthanide) octahedron and reduces the symmetry of the environment around the Ln3+, facilitating the radiative transition rates of Ln3+ while enhancing their ET efficiency. Compared with Cs2NaScCl6:Ln3+, the ET efficiency of Cs2NaScCl6:Sb3+/Ln3+ is enhanced by 1.5-fold, reaching up to 98.3%. To the best of available knowledge, this work is the first to unravel the intrinsic mechanism of enhanced ET process enabled by isoelectronic doping via DFT and J-O theory. This research sheds light on understanding the mechanism of photophysics and rational design of the functional perovskite materials.

Exploring the Physical Properties of LiBeX (X = Sb, Bi) Compounds via Ab Initio Approach

In the current study, it is aimed to scrutinize the physical properties of LiBeX (X = Sb, Bi) compounds in detail. Density‐functional‐theory‐based WIEN2k and the Vienna Ab initio Simulation Package, employing the generalized gradient approximation of Perdew–Burke–Ernzerhof, Wu–Cohen, and Tran–Blaha‐modified Becke–Johnson (TB‐mBJ) exchange‐correlation schemes, are utilized to better validate the outcomes. The compounds exhibit energetic, lattice dynamic, and mechanical stability. Electronic structure calculations using the TB‐mBJ functional reveal indirect bandgaps of 1.007 eV for LiBeSb and 0.789 eV for LiBeBi compounds, respectively. The partial charge distribution in the highest occupied molecular orbital and the lowest unoccupied molecular orbital discloses maximum charge localization around the X site. The examination of the crystal orbital Hamilton population reveals the strongest BeX bonding interactions among the bonding pairs. The physio‐mechanical properties indicate brittle and mechanically anisotropic behavior of both compounds, with covalent bonding characteristics. The comparative analysis suggests that the TB‐mBJ potential is suitable for bandgap calculations due to its close alignment with experimental results. Additionally, the optimized results for these compounds indicate their potential for use in optoelectronic devices, such as visible to ultraviolet sensors and photovoltaics. The determined properties are consistent with previous theoretical findings.

Microscopic analysis of low but stable perovskite solar cell device performance using electron spin resonance

Perovskite solar cells have attracted much attention as next-generation solar cells. However, a typical hole-transport material, spiro-OMeTAD, has associated difficulties including tedious synthesis and high cost. To overcome these shortcomings, an easily synthesized and low-cost hole-transport material has been developed: HND-2NOMe. Although HND-2NOMe has high local charge mobility because of the quasi-planar structure, its lower device performance is a weak point, the cause of which has not yet been clarified. Here, we analyse the source of the lower performance by clarifying the internal states from a microscopic viewpoint using electron spin resonance. We observe hole diffusion from perovskite to HND-2NOMe under dark conditions, indicating hole barrier formation at the perovskite/HND-2NOMe interface, leading to lower performance. Although such a barrier is formed, less hole accumulation for the HND-2NOMe-based cells under solar irradiation occurs, which is related to the stable performance. The sources of the lower but stable performance are crucially important for providing guidelines for improving the device performance.

Cl− skeleton modification and K+ charge compensation construct Eu2+ subcrystalline luminescent structure in NaAlSiO4

In this work, the highly homogeneous NaAlSiO4 structure was constructed by glass relaxation crystallization method. The evolution of the subcrystalline luminescence structure was examined by using Eu2+ as a structural probe. The optimization of luminescent properties and phase structure changes of Cl− substitution, Eu2+ occupancy and K+ charge compensation were studied by XRD, EDS, PL spectra, PLE spectra and luminescence thermal stability analysis. The research revealed the AB layer spacing of the crystal stretched and the hexatomix ring opened by Cl− directionally replace O2−(O5), inducing more Eu2+ to selectively occupy the Na+(I) site, resulting in local charge defects in the lattice. The transition emission efficiency of Eu2+ was increased by 50 % with introducing K+ for directional charge compensation. In comparison with NaAlSiO4:2%Eu2+, the NaAlSiO3.96Cl0.04:2%Eu2+-8K+ phosphor showed a 20.82 % increase in ΔE, indicating improved thermal sensitivity in this phosphor series, which holds promising potential for application in LED devices.

Enhancing smartphone security with human centric bimodal fallback authentication leveraging sensors.

Smartphones store valuable personal information, necessitating robust authentication methods to protect user data. This research proposes a lightweight bi-model fallback authentication technique that combines dynamic security questions and finger pattern recognition using inertial measurement units. The dynamic security questions are generated based on the smartphone's usage behavior, while the owner's finger movements are captured using four different inertial sensors: accelerometer, gyroscope, gravity sensor, and magnetometer. By combining the answers to the questions and the owner's finger movements, the user can be authenticated even if the primary authentication method fails. In this study, data was collected from 24 participants, including 12 primary phone users and 12 close adversaries, over a span of 28 days. The dynamic security questions, derived from call, SMS, battery charging events, application usage, location, and physical activity categories, achieved high accuracy rates, with call, SMS, and application usage surpassing . Incorporating the inertial measurement units significantly improved the accuracy of all question types, increasing from a maximum of to , while also enhancing the True Positive Rate from 0.79 to 0.99 compared to a previous study. This research presents a promising lightweight bi-model fallback authentication technique that leverages dynamic security questions and inertial measurement units data, demonstrating its effectiveness for enhancing smartphone security.

Unconventional mechanical responses and mechanisms of Ti-6Al-4V sheet subjected to electrically-assisted cyclic loading-unloading: Thermal and athermal effects

For the sake of unveiling the macro-micro behaviors and underlying control mechanisms of electroplastic effect (EPE) of sheet metals during recent thriving electrically-assisted incremental forming (EAIF) processes, electrically-assisted cyclic loading-unloading tension (EACT) experiments were carried out at a current density of 14～20A/mm2 followed by forced and unforced cooling. The electro-thermo-mechanical responses and the evolution rules of dislocation configurations, fracture modes, phase composition and local orientation distribution were characterized by IR imaging, SEM, quantitative EBSD and TEM tests. Moreover, the thermal and athermal components of the electrically-induced stress drop throughout the EACT processes were decoupled and systematically analyzed via temperature control tests and isothermal correction. The results show that thermal effect of electric current possesses a great proportion of 75 % in the overall stress drop and plays a key role in elastic modulus degradation and ductility enhancement by activating pyramidal {101‾1}⟨12‾10⟩ slip systems, weakening (0001) texture and promoting dynamic recrystallization (DRX) and α→β→α′ phase transformation. While the athermal effect only operates after reaching both threshold current density and plastic strain, it increases monotonically with current density, brings about “hot spots” effect, local charge imbalance and weakened atomic bonding, and further causes intensified local strain gradient, substructure formation and DRX nucleation. The ratio of athermal stress drop first decreases and then increases significantly with loading cycle at the later stage of EACT under the combined effect of local Joule heating effect and flow localization. Additionally, the athermal effect only activates short-range solute diffusion and localized diffusional α→β phase transformation, while the combined thermal and athermal effects promote long-range solute diffusion and an increasing rate in β content of 261.8 %. The present work provides theoretical basis for optimizing the EAIF forming process and realizing extreme manufacture of light-weight thin-walled complex components.

Discovering Electric Vehicle Charging Locations Based on Clustering Techniques Applied to Vehicular Mobility Datasets

With the proliferation of vehicular mobility traces because of inexpensive on-board sensors and smartphones, utilizing them to further understand road movements have become easily accessible. These huge numbers of vehicular traces can be utilized to determine where to enhance road infrastructures such as the deployment of electric vehicle (EV) charging stations. As more EVs are plying today’s roads, the driving anxiety is minimized with the presence of sufficient charging stations. By correctly extracting the various transportation parameters from a given dataset, one can design an adequate and adaptive EV charging network that can provide comfort and convenience for the movement of people and goods from one point to another. In this study, we determined the possible EV charging station locations based on an urban city’s vehicular capacity distribution obtained from taxi and ride-hailing mobility GPS traces. To achieve this, we first transformed the dynamic vehicular environment based on vehicular capacity into its equivalent urban single snapshot. We then obtained the various traffic zone distributions by initially utilizing k-means clustering to allow flexibility in the total number of wanted traffic zones in each dataset. In each traffic zone, iterative clustering techniques employing Density-based Spatial Clustering of Applications with Noise (DBSCAN) or clustering by fast search and find of density peaks (CFS) revealed various area separation where EV chargers were needed. Finally, to find the exact location of the EV charging station, we last ran k-means to locate centroids, depending on the constraint on how many EV chargers were needed. Extensive simulations revealed the strengths and weaknesses of the clustering methods when applied to our datasets. We utilized the silhouette and Calinski–Harabasz indices to measure the validity of cluster formations. We also measured the inter-station distances to understand the closeness of the locations of EV chargers. Our study shows how CFS + k-means clustering techniques are able to pinpoint EV charger locations. However, when utilizing DBSCAN initially, the results did not present any notable outcome.

Optimized demand-based charging networks for long-haul trucking in Europe

Abstract Battery electric trucks (BETs) are the most promising option for fast and large-scale CO2 emission reduction in road freight transport. Yet, the limited range and longer charging times compared to diesel trucks make long-haul BET applications challenging, so a comprehensive fast charging network for BETs is required. However, little is known about optimal truck charging locations for long-haul trucking in Europe. Here we derive optimized truck charging networks consisting of publicly accessible locations across the continent. Based on European truck traffic flow estimates for 2030 and actual truck stop locations we construct a long-term charging network that minimizes the total number of required locations. Our approach introduces an origin-destination pair sampling method and includes local capacity constraints to compute an optimized stepwise network expansion along the highest demand routes in Europe. For an electrification target of 15% BET share in long-haul and without depot charging, our results suggest that about 91% of electric long-haul truck traffic across Europe can be enabled already with a network of 1,000 locations, while 500 locations would suffice for about 50%. We furthermore show how the coverage of origin-destination flows scales with the number of locations and the size of the stations. Ideal locations to cover many truck trips are at highway intersections and along major European road freight corridors (TEN-T core network).

Cryogenic quantum computer control signal generation using high-electron-mobility transistors

Multiplexed local charge storage, close to quantum processors at cryogenic temperatures could generate a multitude of control signals, for electronics or qubits, in an efficient manner. Such cryogenic electronics require generating quasi-static control signals with small area footprint, low noise, high stability, low power dissipation and, ideally, in a multiplexed fashion to reduce the number of input/outputs. In this work, we integrate capacitors with cryogenic high-electron mobility transistor (HEMT) arrays and demonstrate quasi-static bias generation using gate pulses controlled in time and frequency domains. Multi-channel bias generation is also demonstrated. Operation at 4 K exhibits improved bias signal variability and greatly reduced subthreshold swing, reaching values of ~6 mV/decade. Due to the very low threshold voltage of 80 mV at 4 K and the steep subthreshold swing, these circuits can provide an advantage over the silicon-based complementary metal-oxide-semiconductor equivalents by allowing operation at significantly reduced drive bias in the low output voltage regime <1 V. Together with their high-speed operation, this makes HEMTs an attractive platform for future cryogenic signal generation electronics in quantum computers.

Assessing the Noncovalent Interaction of Deucravacitinib and Ethanol with Special Reference to an Independent Gradient Model Based on Hirshfeld Partition.

The current study begins by optimizing the deucravacitinib molecule in the gas phase at the ωB97XD/cc-pVDZ level of theory using density functional theory and proceeds to study its intramolecular interactions. Further, a molecule of EtOH was introduced at different locations on the deucravacitinib molecule, and the noncovalent interactions arising from them were also investigated using several computational tools. In this way, eight deucravacitinib-EtOH systems (1-8) were identified and their electronic environment was studied after evaluating their binding energy. Using natural bond orbital analysis, the localization of charges between the donor and acceptor fragments in these interacting systems was examined. The nature of interactions was analyzed using the reduced gradient approach (NCI analysis), and few hydrogen bonding interactions (intermolecular and intramolecular) were found in each system. The strength of these hydrogen bonding interactions was further investigated by using theoretical tools such as atoms in molecules analysis and independent gradient model based on Hirshfeld partition analysis. The binding energy of deucravacitinib with EtOH was decomposed into energy components based on the domain-based local pair natural orbital coupled cluster technique using LED analysis. The results from the hydrogen bonding interaction analysis using different computational tools were found to be consistent with the calculated order of binding energy of systems 1-8 and they also pointed toward the higher stability of system 3.

Stabilization of the Compressed Planar Benzene Dianion in Inverse-Sandwich Rare Earth Metal Complexes.

For the first time, the capture of a planar antiaromatic benzene dianion in between two trivalent rare earth (RE) metal cations, each stabilized by two guanidinate ligands, is reported. The synthesized inverse-sandwich complexes [{(Me3Si)2NC(NiPr)2}2RE]2(µ-ƞ6:ƞ6-C6H6), (RE = Y (1), Dy (2), and Er (3)) feature a remarkably planar benzene dianion, previously not encountered for any metal ion prone to low or absent covalency. The -2 charge localization at the benzene ligand was deduced from the results obtained by single-crystal X-ray diffraction analyses, spectroscopy, magnetometry, and Density Functional Theory (DFT) calculations. In the 1H NMR spectrum of the diamagnetic Y complex 1, the equivalent proton resonance of the bridging benzene dianion ligand is drastically shifted to higher field in comparison to free benzene. This and the calculated highly positive Nucleus-Independent Chemical Shift (NICS) values are attributed to the antiaromatic character of the benzene dianion ligand. The crucial role of the ancillary guanidinate ligand scaffold in stabilizing the planar benzene dianion conformation was also elucidated by DFT calculations. Remarkably, the planarity of the benzene dianion originates from the stabilization of the π-type orbitals of the d-manifold and compression through its strong electrostatic interaction with the two REIII sites.

Stabilization of the Compressed Planar Benzene Dianion in Inverse‐Sandwich Rare Earth Metal Complexes

For the first time, the capture of a planar antiaromatic benzene dianion in between two trivalent rare earth (RE) metal cations, each stabilized by two guanidinate ligands, is reported. The synthesized inverse‐sandwich complexes [{(Me3Si)2NC(NiPr)2}2RE]2(µ–ƞ6:ƞ6–C6H6), (RE = Y (1), Dy (2), and Er (3)) feature a remarkably planar benzene dianion, previously not encountered for any metal ion prone to low or absent covalency. The ‐2 charge localization at the benzene ligand was deduced from the results obtained by single‐crystal X‐ray diffraction analyses, spectroscopy, magnetometry, and Density Functional Theory (DFT) calculations. In the 1H NMR spectrum of the diamagnetic Y complex 1, the equivalent proton resonance of the bridging benzene dianion ligand is drastically shifted to higher field in comparison to free benzene. This and the calculated highly positive Nucleus‐Independent Chemical Shift (NICS) values are attributed to the antiaromatic character of the benzene dianion ligand. The crucial role of the ancillary guanidinate ligand scaffold in stabilizing the planar benzene dianion conformation was also elucidated by DFT calculations. Remarkably, the planarity of the benzene dianion originates from the stabilization of the π‐type orbitals of the d‐manifold and compression through its strong electrostatic interaction with the two REIII sites.

First-principles study of oxygen vacancy defects in β-quartz SiO2/Si interfaces

Abstract Understanding the electronic structures of gate oxides in Si-based devices is significant for improving device performance. We investigate the electronic properties of the oxygen vacancy defects in β-quartz SiO2/Si interface structure using first-principles calculations. The results indicate that the constructed (SiO2)4/(Si)4 structure is an indirect-gap semiconductor, with its band edges contributed by Si side and a large band-edge energy difference ( &gt; 1.780 eV). Our study reveals that the presence of oxygen vacancy defects reduces the band gap, and V O 1 is transformed from indirect into direct band gap. The Si dangling bonds in V O 1 cause charge localization around the O vacancy, while the formation of Si–Si bonds in V O 2 and V O 3 lead to electron delocalization. In the calculation of defect formation energies, we find that V O 1 maintains the lowest formation energy across different states, making it more likely to form and structurally stable. Compared to O-rich environments, the formation energy in O-poor environments is overall reduced by approximately 4.5 eV, indicating that oxygen vacancy defects are more likely to form and be controlled under O-poor conditions. Our study emphasizes the importance of interface structure and defect characteristics in semiconductor research, providing insights for the development of Si-based devices.

Probing the effect of Se doping in S cathode for high performance Mg-S batteries

Magnesium-sulfur (Mg-S) batteries present an attractive option as a new type of energy storage device given their high energy density, safety and the use of low-cost original materials. However, magnesium polysulfide (MgPS) is susceptible to dissolution and shuttling, and the insulating nature of sulfur and MgS leads to high overpotentials and low columbic efficiencies. The selenium-sulfur system is noted to offer enhanced electronic conductivity and improved sulfur utilization. In this study, S K-edge X-ray absorption near-edge structure (XANES) spectra demonstrate that Se doping mitigates irreversibility in Mg-S batteries. Mg-K spectra demonstrate that Se dopants induce local negative charges on S, strengthening the Mg-S bond compared to that of pure sulfur, thereby promoting Mg/Mg2+ redox reactions. Operando Raman spectroscopy was also used to reveal Mg-S0.9Se0.1/C battery redox mechanisms. Hence, kinetically favored S0.9Se0.1/C cathodes deliver an initial capacity of ∼1350 mAh·g−1 at 0.2C. Furthermore, separators modified with layered MoS2 entrap polysulfides, thereby postponing cell death. Thus, Mg-S battery with a S0.9Se0.1/C cathode and a MoS2@polypropylene (PP) separator exhibit a reversible capacity of ∼200 mAh·g−1 at 0.2C after 250 cycles, with a low fade rate of 4 mAh·g−1/cycle. This study delineates the overall impact of Se doped cathodes on Mg-S batteries. Moreover, the MoS2 modified separator provides a route to chemically immobilize MgPS and accelerate sulfur redox reactions, consequently enabling high capacities and sustained cycling.

Boosting Alkaline Hydrogen Oxidation Kinetics through Interfacial Environments Induced Surface Migration of Adsorbed Hydroxyl

Constructing bifunctional sites through heterojunction engineering to accelerate water formation has become a pivotal strategy to improve the alkaline hydrogen oxidation reaction (HOR) kinetics, which is mainly focused on the synergistic effect of neighboring sites and the energetics of the surface reaction steps. However, the roles of the surface migration of key intermediates that go beyond the bifunctional mechanism limited to neighboring atoms have usually been ignored. Using the heterostructured Ni3C‐Ni catalyst as a model, we found that the rapid surface migration of OHad species from the positively charged Ni3C to the negatively charged Ni component played a decisive role in facilitating water formation. Such unprecedented surface migration of OHad is induced by the large discrepancy between the local surface charge densities and interfacial environments of the Ni3C and Ni components under operating conditions. Benefiting from this, the resultant Ni3C‐Ni exhibited outstanding mass activity for the alkaline HOR, which was approximately 19‐fold and 21‐fold higher than those of Ni and Ni3C, respectively. These findings not only provide novel insights into the alkaline HOR mechanism of heterostructured catalysts but also open new avenues for developing advanced electrocatalysts for alkaline fuel cells.

Boosting Alkaline Hydrogen Oxidation Kinetics through Interfacial Environments Induced Surface Migration of Adsorbed Hydroxyl.

Constructing bifunctional sites through heterojunction engineering to accelerate water formation has become a pivotal strategy to improve the alkaline hydrogen oxidation reaction (HOR) kinetics, which is mainly focused on the synergistic effect of neighboring sites and the energetics of the surface reaction steps. However, the roles of the surface migration of key intermediates that go beyond the bifunctional mechanism limited to neighboring atoms have usually been ignored. Using the heterostructured Ni3C-Ni catalyst as a model, we found that the rapid surface migration of OHad species from the positively charged Ni3C to the negatively charged Ni component played a decisive role in facilitating water formation. Such unprecedented surface migration of OHad is induced by the large discrepancy between the local surface charge densities and interfacial environments of the Ni3C and Ni components under operating conditions. Benefiting from this, the resultant Ni3C-Ni exhibited outstanding mass activity for the alkaline HOR, which was approximately 19-fold and 21-fold higher than those of Ni and Ni3C, respectively. These findings not only provide novel insights into the alkaline HOR mechanism of heterostructured catalysts but also open new avenues for developing advanced electrocatalysts for alkaline fuel cells.

High Entropy Induced Local Charge Enhancement Promotes Frank–Van der Merwe Growth for Dendrite‐Free Potassium Metal Batteries

AbstractPotassium metal batteries (PMBs) are promising for next‐generation energy storage. However, the high reactivity of the anode causes instability in the solid electrolyte interface (SEI), resulting in Volmer‐Weber (V‐W) type deposition. To achieve uniform Frank‐van der Merwe (F‐M) type deposition, high entropy alloy nanoparticles are designed (HEA NPs) with equimolar ratios of Mn, Fe, Co, Cu, and Ni to enhance the substrate‐K metal interface. HEA NPs enhance the K affinity of the N‐doped nanocarbon fiber substrate (N‐PCNF) and maximize ion and electron transport efficiency. The dendrite‐free horizontal growth of K metal confirmed through Operando X‐ray diffraction (XRD) and optical microscopy (OM). Consequently, the asymmetric cell exhibits ultra‐long cycling stability of 2350 hours at a high current density of 8 mA cm−2. The full cell composed of molten K diffusion into HEA NPs decorated N‐PCNF anode with perylene‐3,4,9,10‐tetracarboxylic dianhydride cathode (HEA‐N‐PCNF‐K||PTCDA) delivers an energy density of 331 W h kg−1 and remains stable over 2000 cycles. This study offers a promising pathway for innovative PMBs designs with broad application prospects.