Critical Current Density Values Research Articles

An in situ-formed LiI interface layer for garnet-based lithium metal batteries

With regard to solid-state electrolytes (SSEs), garnet-type Li6.4La3Zr1.4Ta0.6O12 (LLZT) is a promising option due to its high ionic conductivity and steadiness against lithium metal. However, trace impurities, like Li2CO3 or LiOH, can be easily formed on its surface under ambient atmosphere and significantly influence the conductivity. Herein, the hydrogen iodide (HI) acid vapor is employed to remove surface impurities and a thin LiI layer was in situ generated concurrently. The layer exhibits surprising wetting behavior and high stability towards Li metal and SSE. Benefiting from its unique characteristics, the interface resistance between the LLZT electrolyte and lithium electrode decreased from 6160 to 30 Ω cm2, and the critical current density (CCD) value achieved 1.5 mA cm−2 at room temperature. Specifically, the lithium symmetric battery can cycle steadily for more than 1000 h at a current density of 0.6 mA cm−2. Moreover, a cumulative Li plating capacity of 0.63 Ah cm−2 can be attained. The assembled solid-state batteries (SSBs) show outstanding cycling stability over prolonged cycles at 0.1 C (LiFePO4/LiCoO2@room temperature) and a high rate capacity (LiFePO4: 104.2 mAh g−1 at 0.8 C). This work provides a plausible approach to interfacial issues, thereby paving the path for tangible advancements in SSBs.

Feasible Parameters of Ohmic Areas of YBaCuO Thin Films Switched via Moving Unstable Border between Superconducting and Normal States

A system of two equations based on one of the classical electricity laws was used to determine the sizes and temperatures of ohmic areas formed under action of overcritical nanosecond electrical pulses. Calculations were performed at five points for three experimentally obtained voltage–current (V-I) dependences for samples with the same geometry but different critical current density values. The system included two additional conditions to satisfy the known descriptive model of transition from superconducting (SC) to a normal (N) state—S-N switching—and to obtain physically acceptable solutions over the entire current range of V-I dependence. The solution for each point takes the form of a function, since the initial temperature increase of the primary channel across the film is entered as a parameter. Two modes of concentrated energy release in the channel were disclosed. Their random appearance leads to an unexpected degradation of the sample. As such, the obtained results correspond to the situations occurring during the experiments. The validity of applying additional conditions to the system is discussed. In the discussion, it is also explained at which moments the moving S-N border acquires the velocity of the order of ~106 m/s, comparable to the Fermi velocity. Consideration to describe the moving unstable S-N border as being constantly in a state of Richtmyer–Meshkov instability is presented.

Highly Efficient Aligned Ion-Conducting Network and Interface Chemistries for Depolarized All-Solid-State Lithium Metal Batteries

HighlightsThis study introduces an innovative 3D-printed electrolyte with vertically aligned ion transport network, which contains well-dispersed nanoscale Ta-doped Li7La3Zr2O12 in a poly(ethylene glycol) diacrylate matrix.The 3DSE architecture enables efficient ion transport across the Li/electrolyte and electrolyte/cathode interfaces, which allows for increased active material mass loading and enhanced interfacial adhesion.The p-3DSE Li symmetric cell displays an impressive critical current density value of 1.92 mA cm−2 and stable operation for 2600 h at room temperature. Full cells using p-3DSE achieve notable areal capacities.

The growth mechanism and properties of Bi2212 thin films on miscut substrates by sol-gel method

A sol-gel methodology is employed to prepare Bi2212 thin films on single crystal LaAlO3 miscut substrates with nominal tilt angles of 0°, 5°, 10°, and 15°. The study focuses on examining the phase purity, crystal structure, surface morphology, microstructure, and properties of these thin films. Experimental results indicate that the growth of Bi2212 thin films on miscut substrates proceeds through the step-flow mode using the sol-gel method. Higher tilt angles lead to an increase in the conventional resistivity of Bi2212 thin films. Tilted Bi2212 thin films exhibit a typical transverse Seebeck effect when comparing the resistivity in different directions. Notably, the Seebeck coefficient difference reaches 12 V/K when the substrate tilt angle is set at 15°. Meanwhile, tilted Bi2212 thin films consistently exhibit outstanding superconducting transition temperature (Tc) while demonstrating lower critical current density (Jc) values. These findings offer valuable insights for the development of Bi2212 high temperature superconducting thin films (HTSFs) in thermoelectric and superconductive devices, serving as a reference point for achieving optimal film characteristics.

Record-high critical current density in (Ba,Na)Fe2As2 round wire suitable for high-field applications

Record-high value of transport critical current density (Jc) of 71 kA/cm2 under a field of 100 kOe is achieved in (Ba,Na)Fe2As2 round wire processed under high pressure. This value is realized in a short piece cut out from the 18 m-long wires used for a small demo coil reported in the previous study. To evaluate the transport Jc precisely, the cross-sectional area of the superconducting core is carefully evaluated by X-ray computed tomography (CT) measurements. The achieved Jc value is ∼30 % larger than the previous largest transport Jc among all iron-based superconductors round wires.

Spin–orbit torque-induced memristor in Ta/GdFeCo/Ta structures for neuromorphic computing

Neuromorphic computation of ferrimagnetic materials as artificial synapses is essential for the development of ultra-low power spintronic devices. Here, Ta/GdFeCo/Ta heterostructures are utilized to achieve a spin–orbit torque-driven multistate magnetization switching, complying with the requirements of neuromorphic computation. For Ta/GdFeCo/Ta device, the switching ratio is up to 47.7 % when the critical current density value is 1.26 × 107 A/cm2. Moreover, the βDL and βFL are estimated as 85.64 Oe/(107 A/cm−2) and 35.05 Oe/(107 A/cm−2), respectively. Subsequently, the findings establish that a stable four-resistor state exists, proofing multilevel memory behaviors and synaptic plasticity under current drive. It is further demonstrated that neuromorphic computing built from this SOT device can perform unsupervised handwritten digit recognition with an accuracy of 92.25 %. This research highlights the potential of SOT-driven multi-energy stabilized residual states for neuromorphic computing and multi-energy storage in the future.

Properties of superconducting MgB2 spherical shells deposited on 2 mm and 1 mm diameter Si3N4 spheres

Superconducting spherical shells may not only provide an appealing platform for exploring superconductivity in three-dimensional (3D) geometries with curved surfaces, but also be practically applied in important fields, such as in gyroscopes and gravimeters. In inertial confinement fusion (ICF), the perturbation on the target capsule caused by traditional contact support methods is recognized as one of the major contributors to performance degradation in ICF implosions. It was proposed recently that coating the capsule with a thin superconducting MgB2 spherical shell to realize non-contact support by means of magnetic levitation at the required temperatures K might offer a promising solution to this longstanding problem. To simulate the coating of ICF capsules, we deposited MgB2 spherical shells onto polycrystalline Si3N4 spheres (diameter d = 2 mm and 1 mm) via a hybrid physical–chemical vapour deposition technique. For both diameters, the spherical shells, of about 1 µm in thickness and covering the whole spheres completely, were polycrystalline with thin plate-shaped MgB2 crystallites oriented randomly and closely connected. The spherical shells exhibited superconducting transition at a zero resistance temperature of 38.5–39.4 K in four-probe resistance measurements and ideal diamagnetism at low temperatures in magnetization measurements, suggesting the good crystallinity and homogeneity of the shells. The upper critical field , the irreversibility field and the lower critical field were characterized and showed similar magnitudes and temperature dependencies for the d = 2 mm and 1 mm shells, yielding of 7–8 T and of 7–12 mT at 20 K. The superconducting critical current density values, evaluated from the magnetization hysteresis loops, were A cm−2 and A cm−2 at 20 K under zero and 2 T applied field, respectively, for the d = 1 mm shell. The occurrence of small flux jumps was observed at low temperatures up to 12 K and in low fields below 0.3 T. The results demonstrate the feasibility of fabricating MgB2 spherical shells with properties applicable to potential areas employing magnetic levitation such as in ICF and that MgB2 spherical shells may be exploited as an experimental system to study superconductivity in 3D curvilinear geometry.

Effect of thickness on the superconducting properties of the thin films of FeTe0.55Se0.45 deposited on YSZ substrates using Pulsed laser deposition (PLD) technique

We report the successful fabrication of thin films of thickness ∼26 nm, 59 nm, 76 nm, and 158 nm of the composition FeTe0.55Se0.45 on the (100)-oriented Yttria-stabilized zirconia (YSZ) substrate using the pulsed laser deposition (PLD) technique. The effect of thickness on the structure and superconducting properties of the thin films has been investigated. X-ray diffraction study reveals the growth of thin films along the c-axis. The temperature-dependent resistivity measurements confirm superconductivity in all the fabricated thin films, and the highest ∼ 16.2 K has been observed for the thin film of thickness ∼59 nm, which is higher than the corresponding value of the polycrystalline target sample. The superconducting parameters such as upper critical magnetic field coherence length thermally activated energy (TAE) U0, and vortex phase state have been measured by magnetotransport measurements near in the different applied magnetic fields up to 12 T. The TAE values determined from the conventional and modified thermally activated flux flow (TAFF) models are discussed and compared. A crossover from 2-dimensional (2D) vortex to 3-dimensional (3D) vortex behaviour has been observed. The vortex phase diagrams are used to observe the transition from the vortex liquid to the vortex glass state in the grown thin films. Moreover, magnetoresistance (MR) measurements show non-saturating linear magnetoresistance (LMR) in the high field region, indicating the presence of the possible topological state in the grown thin films. The values of magnetic field dependent transport critical current density, have been evaluated from the current-voltage (I-V) curves. Furthermore, the normalised pinning force density has been used to characterize the pinning processes using the Dew Hughes’ scaling rule which reveals that the grown thin films contain δl-surface pinning centers.

Preparation of argyrodite Li6–2xZnxPS5−xOxCl with improved electrochemical performance and air stability for all-solid-state batteries

The argyrodite Li6PS5Cl (LPSCl) solid electrolyte applied to all-solid-state batteries is gaining increasing attention as an attractive next-generation material, but in humid conditions it causes degradation of battery performance as a result of instability and poor contact with electrodes. In this experiment, LPSCl solid electrolyte was modified by substituting Zn for Li, and O for S through dry ball milling and heat-treatment processing. As evidence of ZnO substitution, X-ray diffraction, Laser-Raman, field emission scanning electron microscopy, nuclear magnetic resonance spectroscopy, and X-ray photoelectron spectroscopy analysis of the synthesized solid electrolyte were performed. The Li5.95Zn0.025PS4.975O0.025Cl (LPSCl-ZnO) solid electrolyte showed a high ionic conductivity at 30 °C. Moreover, it showed a higher critical current density value of 0.55 mA·cm−2 compared to the of 0.3 mA·cm−2 of LPSCl. It also exhibited high compatibility with Li metal as a cathode in cyclic voltammetry and in DC profile. In addition, the H2S gas generated after exposure to 10% humid air was a very low 0.38 cm3·g−1. Notably, an all-solid-state battery assembled with the ZnO-substituted solid electrolyte (x = 0.025) showed a specific capacity of 148.5 mAh·g−1 (0.1 C) and a high capacity retention rate of 99.7%.

Correlation between electron-phonon coupling and superconductivity of Sn2+ ion irradiated MgB2-thin films

This study investigates the impact of 2 MeV Tin ion (Sn2+) irradiation with doses from 2E12 to 7E13 on the Raman spectroscopy and superconductivity properties of MgB2-thin films samples. Raman spectroscopy has been used to examine the behavior of electron-phonon coupling (EPC). For the superconductivity properties, the temperature dependence resistivity, R(T), and the magnetic field-dependent magnetization, M(H), were measured. The import of EPC, which is related to the change in critical temperature (Tc), was calculated using the McMillan-formula modified by Allen–Dynes, using the phonon frequency of the middle peak center ω2(E2g). Raman spectroscopy showed that the value of EPC decreased from 1.113 (Pristine) to 0.969 (7E13). Although the critical temperature (Tc) decreased with increasing Sn2+ ion doses, the values of the in-field critical current density (Jc) and upper critical field (Hc2) increased and reached a maximum for the 5E13 sample. In addition, the magnetic penetration depths of the pristine and optimal dose (5E13) samples were measured using magnetic force microscopy (MFM), providing the thermodynamic critical field (Hc) in the MgB2 films.

Halide/sulfide composite solid-state electrolyte for Li-anode based all-solid-state batteries

Li2ZrCl6 (LZC) solid-state electrolytes (SSEs) have been recognized as a candidate halide SSEs for all-solid-state Li batteries (ASSLBs) with high energy density and safety due to its great compatibility with 4 V-class cathodes and low bill-of-material (BOM) cost. However, despite the benefits, the poor chemical/electrochemical stability of LZC against Li metal causes the deterioration of Li/LZC interface, which has a detrimental inhibition on Li+ transport in ASSLBs. Herein, we report a composite SSE combining by LZC and argyrodite buffer layer (Li6PS5Cl, LPSC) that prevent the unfavorable interaction between LZC and Li metal. The Li/LPSC-LZC-LPSC/Li symmetric cell stably cycles for over 1000 h at 0.3 mA/cm2 (0.15 mAh/cm2) and has a high critical current density (CCD) value of 2.1 mA/cm2 at 25 °C. Under high temperature (60 °C) which promotes the reaction between Li and LZC, symmetric cell fabricated with composite SSE also display stable cycling performance over 1200 h at 0.3 mAh/cm2. Especially, the Li/NCM ASSLBs fabricated with composite SSE exhibit a high initial coulombic efficiency, as well as superior cycling and rate performance. This simple and efficient strategy will be instrumental in the development of halide-based high-performance ASSLBs.

Study on field-based superconducting cable for magnetic energy storage devices

During the design of superconducting magnets, the Ic(B) curve is widely used to evaluate the critical current density distribution in the magnet, safety factor is determined by the lowest value of critical current density and operating current. However, other parts of the magnets will work in over-safe state, which leads to a huge waste of superconducting properties as well as budget problem. This article presents a Field-based cable to improve the utilizing rate of superconducting magnets in SMES system. The quantity of HTS tapes are determined by the magnetic field distribution. By this approach, the cost of HTS materials can be potentially reduced. Firstly, the main motivation as well as the entire design method are introduced. Then, a typical no-insulation coil is designed and fabricated based on Field-based stacked cable to validate the feasibility of this method. Both charging/discharging test and the magnetic field test are carried out to explore the working mechanism of this coil. The unique working performance on time constant and field distribution are analyzed in detail.

DC Electro-Magneto-Mechanical Characterization of 2G HTS Tapes for Superconducting Cable in Magnet System Using Artificial Neural Networks

Characterization of the exact critical current density (Jc) and stress values in twisted superconducting tapes plays an important role for analyzing their magnetic, thermal, and mechanical behaviors. In current study, a model based on artificial neural network (ANN) is introduced to estimate the electro-magneto-mechanical characteristic of different superconducting tapes. For this purpose, magnetic flux density, temperature, strain, total thickness of tape, it's width, thickness of stabilizer, and thickness of substrates are used as inputs to ANN model, whereas minimum normalized Jc and maximum stress are considered as outputs. The required experimental data are extracted from published papers in the literature. The ANN model was trained for Jc/stress estimation using extracted data by using different inputs. Sensitivity analysis was conducted on ANN models, which were used to estimate the Jc and stress values of tapes, to choose an optimum structure for ANN models to be used in future by other researchers in the superconductivity community. To check the reproducibility, repeatability, and stability of presented results, the estimations with ANN optimum structure were tested for 500 testing runs. We found that the ANN optimum structure was as one hidden layer with Levenberg–Marquardt training method and seven inputs. Comparing to the literature, the proposed ANN model offers about 15% and 1.1% higher accuracy in Jc and stress estimations, respectively.

High-performance joints between iron-based superconductors: a key step towards applications

Abstract In 2008 the first of a new group of superconducting materials, the iron-based superconductors (IBS), was reported [1]. Apart from the intrinsic physics interest it quickly became clear that these materials have favourable characteristics from an applied superconductivity standpoint. They have a relatively high critical temperature (Tc), up to 55 K [2], along with a high upper critical field, Hc2 > 100 T [3] and low Hc2 anisotropy (with the best achieving anisotropy in superconducting properties of about 1.5, compared to a minimum for cuprates of approximately 5) [3–5]. They can also achieve values of critical current density above 105 A cm-2 in fields over 10 T [6]. Despite the youth of the field, research into these materials has been conducted at pace [7].

The study of superconducting and magnetic properties of bis oxalate (C22H22O6) added bulk MgB2

The effect of bis oxalate (C22H22O6) addition on critical current density (Jc), lattice parameters, microstructure, superconducting temperature (Tc), magnetic levitation force (Fz) and lateral force (Fx) properties of bulk MgB2 has been studied for the first time in this study. Bulk MgB2 samples containing × wt% C22H22O6 (x ranging from 0, 1.5, 3, 4.5, 6 and 9 wt%) were fabricated with by in-situ solid state sintering technique at 775 °C. Fz and Fx measurements at 25 K and 30 K were made under zero-field-cooled (ZFC) and field- cooled (FC) regimes. The analysis of XRD and SEM points out a drop in lattice parameters and grain size of bis oxalate added samples and endorses C replacement in B sites in MgB2 lattice. It was observed that the bis oxalate addition has a progressive effect on magnetic levitation performance of MgB2. Whereas the maximum Fz and Fx values of undoped sample show 16.91 N and 7.10 N at 25 K, the maximum force values of the 3 wt% (BO) added sample correspond to 18.62 N and 8.49 N at 25 K. Furthermore, the (BO) addition meaningfully rises the critical current density (Jc) values of MgB2. The Jc values observed as 57 kA/cm2 and 70 kA/cm2 in self-field at 25 K for pure and 3 wt% (BO) doped MgB2 sample. The experimental results reveal that C22H22O6, as an example of carbohydrate, is an effective C-containing additive for the enhancement of the superconducting and magnetic levitation capacities of MgB2.

The effect of sintering conditions on the superconducting properties of melanin doped MgB2

In this work, the melanin-doped MgB2 samples were prepared under the same condition at different sintering temperatures. The XRD quantitative analysis indicates an increase in crystallite size with increasing sintering temperature. The pinning mechanism tends to be a collective of surface and point pinning in an indication of the role of the impurities and secondary phases in the forming of flux pinning centers. The electrical and magnetic measurements show significant enhancement on critical current density obtained from the doped samples compared to the pure ones. Enhancing critical current density and critical fields depend on the sintering conditions. Sintering at low-temperature results in a high critical current density and critical field values. The resistivity and the related superconducting parameters measurements were also completed.

Rare Earth Oxide-Assisted Sintered NASICON Electrolyte Composed of a Phosphate Grain Boundary Phase with Low Electronic Conductivity

A NASICON-type electrolyte was considered to be one of the most promising electrolytes for solid-state Na metal batteries. However, its lower ion conductivity compared to a liquid electrolyte and the formation of Na dendrites hinder its practical application. Herein, NASICON-type (Na3Zr2Si2PO12) solid-state electrolytes with developed ionic conductivity and declined electronic conductivity were synthesized through the rare earth oxide-assisted sintering method, such as Sm2O3 and Ho2O3. With the presence of Sm2O3 and Ho2O3 during sintering, the formed phosphate grain boundary phase adjusts the Si/P ratio in the NASICON structure with higher Na+ occupancy and then enhances the ionic conductivity of electrolytes. On the other hand, the formed phosphate grain boundary phase with low electronic conductivity prevents the movement of electrons at the grain boundary, reducing the probability that electrons combine with Na+ at the grain boundary to form Na0, thereby restricting the formation of dendrites along grain boundaries. In addition, the added Sm2O3 and Ho2O3 play the role of fluxing agents to increase the densification of ceramics, further enabling the enhancement of ionic conductivity and restriction of dendrites in the voids. As a result, the obtained NZSP-0.2Sm and NZSP-0.3Ho electrolytes deliver critical current density (CCD) values of 0.85 and 0.65 mA cm–2, respectively, at room temperature. Application of the obtained electrolytes in Na metal batteries is evaluated by assembling Na3V2(PO4)3|NZSP-0.2Sm/0.3Ho|Na cells, which deliver high discharge capacity values of 102.6 and 101.8 mAh g–1 at 0.5 C after 100 cycles with capacity retention ratios of 98.3 and 98.6%, respectively. The presented results indicated that rare earth oxide-assisted sintering is an effective route to improve the ionic conductivity and restrict dendrite formation for oxide ceramic solid-state electrolytes.

High-Rate Lithium Metal Plating and Stripping on Solid Electrolytes Using a Porous Current Collector with a High Aperture Ratio

Dendritic Li metal growth and low Coulombic efficiency hinder the Li metal negative electrode’s applications. Solid electrolytes (SEs) have the potential to inhibit the growth of dendritic Li metal due to their high mechanical strength and number of transmissions; however, the extrusion of the Li metal into voids and cracks in the SEs due to the increased mechanical stress of the Li metal during the plating reaction makes it difficult to prevent internal short circuits. Here, this obstacle was uniquely solved using a porous current collector (PCC) with a high aperture ratio. Li metal plating in many pores of the PCC prevented the increase of mechanical stress of the Li metal. Moreover, the combination with the SE, which also has a high tolerance to the dendritic Li metal growth, showed a synergic effect. Additionally, the Au coating on the PCC’s surface extended the Li plating/stripping performance. As a result, a record-high value of critical current density (the maximum plating/stripping current density without internal short circuits) over 6 mA cm–2 was recognized by the galvanostatic Li metal plating/stripping tests. Notably, the excellent cycle performance with a high average Coulombic efficiency of 98.7% for 300 cycles was also achieved in the Li electrode-free system. Our works exhibit the potential for attaining Li metal all-solid-state cells.

Multistep atomic layer deposition process for ultrathin superconducting NbN films with high critical current density on amorphous substrate

This study presents a multistep process of plasma-enhanced atomic layer deposition of ultrathin superconductive films of niobium nitride from metal organic precursor tris(diethylamido)(tert-butylimido)niobium(V). While using NH3/Ar and H2/Ar gas mixtures as reactants, a comprehensive analysis was performed pertaining to the influence of operating parameters, such as the duration of plasma exposure to the H2/Ar reactant, gas-flow ratio, plasma exposure duration and power of inductively coupled plasma source for the NH3/Ar reactant, on the obtained films’ parameters, such as resistivity, superconducting transition temperature and critical current density. Amorphous silicon oxide was used as the substrate. It was shown by experiments, that films’ resistivity affects the value of critical current density. As a result, the all-time record resistivity of 147 µΩ·cm was achieved for films with a thickness of 8 nm. When cooling in the Gifford McMahon closed-cycle cryostat, the values of superconducting transition temperature and critical current density were equal to 12.3 К and 9 МА/cm2 at a liquid helium temperature, respectively.

CVD Yöntemi ile Karbon Katkılanmış Bor Kullanılarak Üretilen MgB2 Süperiletkeninin Yapısal ve Manyetiksel Özelliklerine Sıcaklık Etkisinin İncelenmesi

Carbon, which is known to play a improvement role on the superconductivity properties of MgB2, was doped into MgB2 by CVD (chemical vapor deposition) method, and the change of structural and magnetic properties observed in MgB2 in relation to the change of sintering temperature was investigated. In this context, in the sample preparation step, amorphous nano boron powders with carbon added by chemical vapor deposition method were mixed with magnesium powders at certain mass ratios and sintered at four different temperatures (700-800-900-1000 0C) with the classical solid state reaction method and converted into carbon-added MgB2 samples. SEM photographs of amorphous nano-boron powders with carbon added were taken and subjected to elemental analysis. The structural and magnetic properties of the samples obtained were examined. X-ray diffraction graph, magnetization values and Magnetic Field-Magnetic Moment (M-H) graphs of the samples obtained by XRD method and the critical current density values with Bean Method were found and Magnetic Field-Critical Current Density (Jc-H) graph was created. It was determined that, in all the samples obtained, the MgB2 superconductor structure was formed and the carbon structures included in the structure caused changes in the lattice parameters due to the ion radius difference, that fracture occurred in the magnetization curve of the sample prepared by sintered at 1000 0C due to the intense impurities caused by the phase transitions due to the high temperature, in samples prepared at low temperatures, and that magnetization curves that could not expand sufficiently were observed, flux jumping occurs in the magnetization curve and this also affected the critical current density. In addition, the change in the critical current density value from 7.0×10^3 A/cm2 to 2.8×10^4 A/cm2 showed that the reaction temperature was an effective parameter on the experimental results. As a result of the examinations, when compared between the 4 different sintering temperature values used, it was found that the sintering temperature of 900 0C was the temperature at which the best physical results were obtained in MgB2.