High Critical Current Density Research Articles

Bonded Interface Enabled Durable Solid‐state Lithium Metal Batteries with Ultra‐low Interfacial Resistance of 0.25 Ω cm2

AbstractThe solid‐state batteries (SSBs) with Li anode present one of the most promising energy storage systems due to their enhanced energy density and safety. However, interfacial problems between Li anode and solid‐state electrolyte hinder the advancement of SSBs. Among them, insufficient solid‐solid interfacial contact is the main issue, which causes large resistance and hinders Li+ diffusion, leading to current distribution unevenness and lithium dendrites growth. To meet these challenges, a silver/carbon interlayer composed of ultrafine Ag nanoparticles (≈5 nm) grown on COOH‐CNTs (nano‐Ag@COOH‐CNTs) is constructed. In which, nano‐Ag is designed to guide homogeneous Li deposition, while CNTs substrate bonds with Li6.5La3Zr1.5Ta0.5O12 (LLZTO) electrolyte by reactions between ─COOH groups and LLZTO alkaline surface, thus transforming loose physical solid‐solid contact to chemical bonding contact. In addition, nano‐Ag is immobilized by CNTs, avoiding the migration of Li+ implanted nano‐Ag during cycling. Therefore, nano‐Ag@COOH‐CNTs interlayer can boost Li+ transport at LLZTO/Li interface and inhibit Li dendrites, achieving an ultra‐low interfacial resistance of 0.25 Ω cm2, a high critical current density of 1.7 mA cm−2 and a long cycling over 2155 h at 0.5 mA cm−2. The modified SSBs with LiNi0.83Co0.12Mn0.05O2 cathode cycles stably over 500 cycles. Moreover, high‐loading SSBs operate stably for 85 cycles.

Fabrication of microstrips of iron-based superconductor NdFeAs(O,H)

NdFeAs(O,H) microstrips with line widths of about 1–5 µm were fabricated by photolithography and Ar-ion dry etching. The microstrips were fabricated under two different etching conditions: 25 min etching at a power of 20 W (long duration, low power) and 3 min etching at 100 W (short duration, high power). For both conditions, the narrowest microstrips, which were 0.9 µm in width, retained high critical temperatures of about 85% of those before microfabrication. Further, the 0.9 µm microstrip fabricated under the high-power, short-duration condition exhibited a high critical current density (J c) of more than 4 MA cm−2 at 4 K. However, J c of the microstrip fabricated under the low-power, long-duration condition was somewhat lower. Our analysis suggests that the edges of the microstrips were damaged more than twice as wide as those of the microstrips fabricated under the high-power, short-duration condition. This indicates that a short duration is more effective to reduce the damage than using a lower etching power.

High-Strength, Thin, and Lightweight Solid Polymer Electrolyte for Superior All-Solid-State Sodium Metal Batteries.

The utilization of solid polymer electrolytes (SPEs) in all-solid-state sodium metal batteries has been extensively explored due to their excellent flexibility, processability adaptability to match roll-to-roll manufacturing processes, and good interfacial contact with a high-capacity Na anode; however, SPEs are still impeded by their inadequate mechanical strength, excessive thickness, and poor stability with Na anodes. Herein, a robust, thin, and cost-effective polyethylene (PE) film is employed as a skeleton for infiltrating poly(ethylene oxide)-sodium bis(trifluoromethanesulfonyl)imide (PEO/NaTFSI) to fabricate PE-PEO/NaTFSI SPE. The resulting SPE features a remarkable thickness of 25 μm, lightweight property (2.1 mg cm-2), superior mechanical strength (tensile strength = 100.3 MPa), and good flexibility. The SPE also shows an ionic conductivity of 9.4 × 10-5 S cm-1 at 60 °C and enhanced interfacial stability with a sodium metal anode. Benefiting from these advantages, the assembled Na-Na symmetric cells with PE-PEO/NaTFSI show a high critical current density (1 mA cm-2) and excellent long-term cycling stability (3000 h at 0.3 mA cm-2). The all-solid-state Na||PE-PEO/NaTFSI||Na3V2(PO4)3 coin cells exhibit a superior cycling performance, retaining 93% of the initial capacity for 190 cycles when matched with a 6 mg cm-2 cathode loading. Meanwhile, the pouch cell can work stably after abuse testing, proving its flexibility and safety. This work offers a promising strategy to simultaneously achieve thin, high-strength, and safe solid-state electrolytes for all-solid-state sodium metal batteries.

In Situ Fabrication of High Ionic and Electronic Conductivity Interlayers Enabling Long-Life Garnet-Based Solid-State Lithium Batteries.

Garnet-type Li6.75La3Zr1.75Ta0.25O12 (LLZTO) is a promising solid-state electrolyte (SSE) because of its fast ionic conduction and notable chemical/electrochemical stability toward the lithium (Li) metal. However, poor interface wettability and large interface resistance between LLZTO and Li anode greatly restrict its practical applications. In this work, we develop an in situ chemical conversion strategy to construct a highly conductive Li2S@C layer on the surface of LLZTO, enabling improved interfacial wettability between LLZTO and the Li anode. The Li/Li2S@C-LLZTO-Li2S@C/Li symmetric cell has a low interface impedance of 78.5 Ω cm2, much lower than the 970 Ω cm2 of a Li/LLZTO/Li cell. Moreover, the Li/Li2S@C-LLZTO-Li2S@C/Li cell exhibits a high critical current density of 1.4 mA cm-2 and an ultralong stability of 3000 h at 0.1 mA cm-2. When used in a LiFePO4 battery, the Li/Li2S@C-LLZTO/LiFePO4 battery exhibits a high initial discharge capacity of 150.8 mA h g-1 at 0.2 C without lithium storage capacity attenuation during 200 cycles. This work provides a novel and feasible strategy to address interface issues of SSEs and achieve lithium-dendrite-free solid-state batteries.

Removal and Reoccurrence of LLZTO Surface Contaminants under Glovebox Conditions.

The reactivity of Li6.4La3Zr1.4Ta0.6O12 (LLZTO) solid electrolytes to form lithio-phobic species such as Li2CO3 on their surface when exposed to trace amounts of H2O and CO2 limits the progress of LLZTO-based solid-state batteries. Various treatments, such as annealing LLZTO within a glovebox or acid etching, aim at removing the surface contaminants, but a comprehensive understanding of the evolving LLZTO surface chemistry during and after these treatments is lacking. Here, glovebox-like H2O and CO2 conditions were recreated in a near ambient pressure X-ray photoelectron spectroscopy chamber to analyze the LLZTO surface under realistic conditions. We find that annealing LLZTO at 600 °C in this atmosphere effectively removes the surface contaminants, but a significant level of contamination reappears upon cooling down. In contrast, HCl(aq) acid etching demonstrates superior Li2CO3 removal and stable surface chemistry post treatment. To avoid air exposure during the acid treatment, an anhydrous HCl solution in diethyl ether was used directly within the glovebox. This novel acid etching strategy delivers the lowest lithium/LLZTO interfacial resistance and the highest critical current density.

Superior Superconducting Properties Realized in Quaternary La-Y-Ce Hydrides at Moderate Pressures.

The recent revolution in the superconductivity field stems from hydride superconductors. Multicomponent hydrides provide a crucial platform for tracking high-temperature superconductors. Besides high superconducting transition temperature (Tc), achieving both giant upper critical magnetic field [μ0Hc2(0)] and high critical current density [Jc(0)] is also key to the latent potential of the application for hydride superconductors. In this work, we have successfully synthesized quaternary La-Y-Ce hydrides with excellent properties under moderate pressure by using the concept of "entropy engineering." The obtained temperature dependence of the resistance provides evidence for the superconductivity of Fm3m-(La,Y,Ce)H10, with the maximum Tc ∼ 190 K (at 112 GPa). Notably, Fm3m-(La,Y,Ce)H10 boasts exceptional properties: μ0Hc2(0) reaching 292 T and Jc(0) surpassing 4.61 × 107 A/cm2. Compared with the binary LaH10/YH10, we find that the Fm3m structure in (La,Y,Ce)H10 can be stable at relatively low pressures (112 GPa). These results indicate that multicomponent hydrides can significantly enhance the superconducting properties and regulate stabilizing pressure through the application of "entropy engineering." This work stimulates the experimental exploration of multihydride superconductors and also provides a reference for the search of room-temperature superconductors in more diversified hydride materials in the future.

Zwitterionic Cellulose-Based Polymer Electrolyte Enabled by Aqueous Solution Casting for High-Performance Solid-State Batteries.

Polyethylene oxide (PEO)-based solid-state batteries hold great promise as the next-generation batteries with high energy density and high safety. However, PEO-based electrolytes encounter certain limitations, including inferior ionic conductivity, low Li+ transference number, and poor mechanical strength. Herein, we aim to simultaneously address these issues by utilizing one-dimensional zwitterionic cellulose nanofiber (ZCNF) as fillers for PEO-based electrolytes using a simple aqueous solution casting method. Multiple characterizations and theoretical calculations demonstrate that the unique zwitterionic structure imparts ZCNF with various functions, such as disrupting PEO crystallization, dissociating lithium salts, anchoring anions through cationic groups, accelerating Li+ migration by anionic groups, as well as its inherent reinforcement effect. As a result, the prepared PL-ZCNF electrolyte exhibits remarkable ionic conductivity (5.37×10-4 S cm-1) and Li+ transference number (0.62) at 60 °C without sacrificing mechanical strength (9.2 MPa), together with high critical current density of 1.1 mA cm-2. Attributed to these merits of PL-ZCNF, the LiFePO4|PL-ZCNF|Li solid-state full-cell delivers exceptional rate capability and cycling performance (900 cycles at 5 C). Notably, the assembled pouch-cell can maintain steady operation over 1000 cycles with an impressive 93.7 % capacity retention at 0.5 C and 60 °C, highlighting the great potential of PL-ZCNF for practical applications.

Zwitterionic Cellulose‐based Polymer Electrolyte Enabled by Aqueous Solution Casting for High‐performance Solid‐state Batteries

Polyethylene oxide (PEO)‐based solid‐state batteries hold great promise as the next‐generation batteries with high energy density and high safety. However, PEO‐based electrolytes encounter certain limitations, including inferior ionic conductivity, low Li+ transference number, and poor mechanical strength. Herein, we aim to simultaneously address these issues by utilizing one‐dimensional zwitterionic cellulose nanofiber (ZCNF) as fillers for PEO‐based electrolytes using a simple aqueous solution casting method. Multiple characterizations and theoretical calculations demonstrate that the unique zwitterionic structure imparts ZCNF with various functions, such as disrupting PEO crystallization, dissociating lithium salts, anchoring anions through cationic groups, accelerating Li+ migration by anionic groups, as well as its inherent reinforcement effect. As a result, the prepared PL‐ZCNF electrolyte exhibits remarkable ionic conductivity (5.37 × 10−4 S cm−1) and Li+ transference number (0.62) at 60 °C without sacrificing mechanical strength (9.2 MPa), together with high critical current density of 1.1 mA cm−2. Attributed to these merits of PL‐ZCNF, the LiFePO4|PL‐ZCNF|Li solid‐state full‐cell delivers exceptional rate capability and cycling performance (900 cycles at 5 C). Notably, the assembled pouch‐cell can maintain steady operation over 1000 cycles with an impressive 93.7% capacity retention at 0.5 C and 60 °C, highlighting the great potential of PL‐ZCNF for practical applications.

Interfacial Design Strategy for Polymeric Lithium Metal Batteries with Superfast Charge‐Transfer Kinetics

AbstractInterfacial instability including the high charge‐transfer resistance and the uncontrolled lithium dendrite growth have severely restricted the safety, fast‐charging, and high‐power capabilities of solid‐state polymeric lithium metal batteries (PLMBs). Here, the study demonstrates the ionic nanoclusters self‐assembled between the lithium ions and a rigid‐rod sulfonated aromatic polyamide Poly 2,2′‐disulfonyl‐4,4′‐benzidine terephthalamide (PBDT) can facilitate uniform lithium deposition; meanwhile, realizing 102–103 times lower interfacial charge‐transfer resistance than PEO‐based electrolytes and excellent lithium dendrite suppression at the interfaces. The cells assembled with this solid‐state polymer electrolyte at room temperature show a record high critical current density (6 mA cm−2/3 mAh cm−2), 80% capacity retention at 10 000 cycles (5 C) with the LiFePO4 cathode. With the temperature increased to 80 °C, the cells enable almost 100% of the theoretical capacity at 3 C and high specific power density (20 kW kg−1). According to the Cryo‐TEM imaging and computational simulation results, it is concluded that these nanoscale self‐assembled ionic nanoclusters play a critical role in realizing the superfast charge‐transfer kinetics by balancing the pre‐exponential factor and activation energy at the lithium‐polymer space‐charge interfaces. This interfacial design strategy based on thermodynamically favored ion‐association and self‐assembly between the metal ions and the polyanions guarantees superior charge‐transfer kinetics in PLMBs.

Synthesis and characterization of BaIrO3-doped YBCO superconducting thin films via TFA-MOD technique

High-temperature superconducting materials (HTS) are characterized by remarkably high critical current density (Jc) values when exposed to low temperatures and magnetic fields. In the realm of such investigations, various crystalline imperfections, including finely dispersed non-superconducting phases, dislocations, vacancies, grain boundaries, twin boundaries, antiphase boundaries, and insulating regions within grain boundaries, have been recognized as potential sources of pinning centers. However, it is essential to acknowledge that Jc values experience a rapid decline as the temperature rises in the presence of a magnetic field. The primary contributing factors to this decline are attributed to the intrinsic crystalline anisotropy of HTS materials and the thermal fluctuations that prevail at elevated temperatures. Nevertheless, a noteworthy factor in the diminishment of Jc values is the scarcity of efficacious pinning centers. In response to these challenges, a pioneering technology has emerged, revolving around nanostructure engineering for the deliberate creation of artificial pinning centers within HTS materials. In alignment with this approach, the present study endeavors to augment the critical current density and enhance the flux pinning properties of YBa2Cu3O6.56 (YBCO) superconducting films. This augmentation is achieved through the integration of BaIrO3 (BIO) perovskite nanodots, nanorods, or nanoparticles as strategically positioned pinning centers. The films are deposited on a SrTiO3 (STO) substrate employing the Trifluoroacetate Metal–Organic Deposition (TFA-MOD) technique. This research initiative seeks to contribute to the advancement of knowledge regarding the controlled manipulation of artificial pinning centers in HTS materials, particularly focusing on YBCO thin films, with the ultimate goal of enhancing their performance under the influence of elevated magnetic fields.

Superconducting nanowire single-photon detectors with saturated quantum efficiency at 1550 nm on single-crystal diamond substrates

Single-crystal diamond possesses exceptional physical and optical properties, rendering it an ideal platform for integrated quantum optics. The direct integration of broadband-sensitive and high-performance single-photon detectors on diamond holds significant implications for the realization of integrated diamond quantum optical circuits. In this study, we polished the diamond surface with RMS (root mean square) below 0.6 nm suitable for the deposition and patterning of NbN thin films through ion beam etching. Subsequently, we fabricated superconducting nanowire single-photon detectors directly on the polished diamond substrates and characterized for their electrical and optical properties. The NbN-SNSPD exhibited a high critical current density (2 MA cm−2), a saturated quantum efficiency (QE) below 2.5 K, and a maximum value of QE up to 88% at 4 K. These findings offer a promising solution for fully integrated quantum optical chips on single-crystal diamond substrates.

In Situ Polymerization Inhibiting Electron Localization in Hybrid Electrolyte for Room‐Temperature Solid‐State Lithium Metal Batteries

AbstractHybrid solid electrolytes (HSEs) have attracted much attention due to their advantages as both inorganic and organic polymer electrolytes. However, the organic/inorganic interfacial space charge layer has a great barrier to the transport of Li+ in the HSE. Here, an in situ polymerization layer is proposed on garnet‐type particles, working as the coherent region to eliminate the space charge layer at the organic/inorganic interfaces by inhibiting electron localization. The conjugate hybridization of fillers weakens the aggregation of particles, induces the dissociation of Li salt, and provides high‐throughput Li+ transport pathways at the ceramics/polymer interface. Furthermore, the continuous Li+ conduction networks are connected by the coherent region between inorganic fillers and polymer chains. The fabricated HSE exhibits a high ionic conductivity of 0.47 mS cm−1 and ion migration numbers of 0.78 at room temperature. The 3D Li//Li systematic battery assembled with the HSE delivers a high critical current density (CCD) of 2.0 mA cm−2. Meanwhile, the 4.5 V NCM811//Li batteries achieve a prolonged operation of 500 cycles at 0.5 C. The Li//LiFePO4 batteries demonstrate superior capacity retention of 96.4% at 1 C after 500 cycles.

A Hybrid LiCl/LixSn Conductive Interlayer to Unlock the Potential of Solid‐State Lithium Metal Batteries

AbstractLi1.3Al0.3Ti1.7(PO4)3 (LATP) electrolyte has a great potential for application in solid‐state lithium metal batteries. However, due to the poor interfacial contact and thermodynamic instability between LATP and Li metal, a series of interfacial problems, such as high interfacial resistance, undesirable interfacial reaction and dendrite growth are deeply criticized. Herein, a hybrid LiCl/LixSn conductive interlayer is constructed through an in situ electrochemical reaction of SnCl4 with Li metal to effectively improve the compatibility and stability of the Li/LATP interface. LiCl with both electronic insulation and high ionic conductivity can provide fast Li+ diffusion channel, block electron injection, avoid side reactions, and effectively inhibit dendrite growth. LixSn can reduce interfacial impedance, eliminate local electric field concentration, and significantly improve interfacial wettability. Under the protection of LiCl/LixSn hybrid interlayer, the initial resistance of the symmetric battery is reduced from 1066.3 to 133.6 Ω cm−2, achieving a high critical current density of 1.4 mA cm−2. At 0.1 mA cm−2/0.1 mAh cm−2 and 0.2 mA cm−2/0.2 mAh cm−2, the symmetric battery can cycle stably for more than 4000 h at 25 °C. Moreover, the full battery displays a high capacity retention ratio of 90.4% after 420 cycles at 0.5 C.

NbN-based half-flux-quantum element for integration with superconducting qubits

Half-flux-quantum (HFQ) logic is a superconductor logic family comprising conventional Josephson junctions (0-JJs) and π Josephson junctions (π-JJs). The energy scale of HFQ logic can be flexibly reduced by phase shifts owing to π-JJs; thus, HFQ circuits are a promising building block for qubit interface circuits. In this study, we demonstrate an NbN-based HFQ circuit element compatible with NbN-based superconducting qubits for all-NbN monolithic integration of qubits and HFQ circuits. The use of NbN is beneficial for both qubits and HFQ circuits owing to its high-quality junctions and high kinetic inductance. First, we developed a prototype of an NbN-based 0-JJ/π-JJ hybrid fabrication process for designing HFQ circuits. We evaluated 0-JJs and π-JJs fabricated through the hybrid process, which demonstrated that the 0-JJs had a small deviation with regard to critical current density and the π-JJs had a sufficiently high critical current density to work as π phase shifters. Furthermore, we fabricated an HFQ superconducting quantum interference device, which is one of the most fundamental elements in HFQ circuits, and observed clear HFQ-period modulation in the magnetic flux dependence of the maximum current at 4.2 K.

Lithium Superionic Conductive Nanofiber-Reinforcing High-Performance Polymer Electrolytes for Solid-State Batteries.

Although composite solid-state electrolytes (CSEs) are considered promising ionic conductors for high-energy lithium metal batteries, their unsatisfactory ionic conductivity, low mechanical strength, poor thermal stability, and narrow voltage window limit their practical applications. We have prepared a new lithium superionic conductor (Li-HA-F) with an ultralong nanofiber structure and ultrahigh room-temperature ionic conductivity (12.6 mS cm-1). When it is directly coupled with a typical poly(ethylene oxide)-based solid electrolyte, the Li-HA-F nanofibers endow the resulting CSE with high ionic conductivity (4.0 × 10-4 S cm-1 at 30 °C), large Li+ transference number (0.66), and wide voltage window (5.2 V). Detailed experiments and theoretical calculations reveal that Li-HA-F supplies continuous dual-conductive pathways and results in stable LiF-rich interfaces, leading to its excellent performance. Moreover, the Li-HA-F nanofiber-reinforced CSE exhibits good heat/flame resistance and flexibility, with a high breaking strength (9.66 MPa). As a result, the Li/Li half cells fabricated with the Li-HA-F CSE exhibit good stability over 2000 h with a high critical current density of 1.4 mA cm-2. Furthermore, the LiFePO4/Li-HA-F CSE/Li and LiNi0.8Co0.1Mn0.1O2/Li-HA-F CSE/Li solid-state batteries deliver high reversible capacities over a wide temperature range with a good cycling performance.

Non‐Resonant Structure Induces N‐Rich Solid Electrolyte Interface toward Ultra‐Stable Solid‐State Lithium‐Metal Batteries

AbstractThe practical application of all‐solid‐state lithium metal batteries (ASSLMBs) is limited by lithium (Li) anode instability including Li dendrite formation and deteriorating interface with electrolytes. Here, a functional additive, isosorbide mononitrate (ISMN) with a non‐resonant structure (O2−N−O−) is reported, which improves its reactivity and is utilized to build a stable N‐rich solid electrolyte interface, effectively alleviating Li dendrite and side reactions for poly(vinylidene fluoride) (PVDF)‐lithium bis(trifluoromethane sulfonyl) imide (LiTFSI)‐based electrolyte (PLE‐ISMN). In addition, the ion‐dipole interaction between ISMN and Li ions facilitates the dissociation of LiTFSI to form carrier ions, improving the ionic conductivity (4.4 × 10−4 S cm−1) and transference number (0.50) of PLE‐ISMN. Consequently, the Li/Li symmetric cell delivers a high critical current density of 2.0 mA cm−2 and stable Li stripping/plating cycling over 5000 h with a capacity of 1.0 mAh cm−2. Moreover, the Li|LiFePO4 cell delivers an excellent initial discharge capacity of 154.0 mAh g−1 with an outstanding capacity retention of 88.9% after 500 cycles at 0.5 C. The Li|LiNi0.8Co0.1Mn0.1O2 cell also exhibits a good cycling performance at 4.4 V at 1 C.

R-z plane spatial critical current inhomogeneity-induced mechanical response of GdBCO superconducting bulks during field cooling magnetization

Benefiting from the high critical current density (J c), single-grain (RE)BCO (where RE = rare earth or Gd) bulks are capable of trapping over 17.6 T magnetic field which is crucial for the application of bulk superconductors. Nevertheless, during field cooling magnetization (FCM), the large mechanical stress induced by Lorentz forces may lead to fracture behavior in the brittle ceramic nature of (RE)BCO materials. Most previous numerical models that adopted simplified homogeneous J c had difficulty reflecting the real stress/strain situation in high temperature superconductor (HTS) bulks. Based on the proposed modified Jirsa model considering r-z plane J c inhomogeneity, we investigate the mechanical response of GdBCO bulks manufactured by top-seeded melt growth (TSMG) process. A 2D axisymmetric electromagnetic-thermal-mechanical coupled model is implemented to take into account the dependence of J c upon mechanical deformation. The simulation results show the electromagnetic-thermal-mechanical response of the r-z plane inhomogeneous J c model is lower than that obtained by the homogeneous J c model. This confirms Takahashi’s speculation (K Takahashi 2019 Supercond. Sci. Technol. 32 015007) about the mismatch between experimental data and the simulation results of homogeneous J c model, and suggests the stress levels in the bottom plane of HTS bulk are overestimated by the previous homogeneous J c model. On top of that, the overall stress level of GdBCO bulk is strongly determined by the magnitude and position of the Lorentz force load, and the stress distribution of inhomogeneous J c model is mainly concentrated in high J c regions near top surface, instead of being symmetrically distributed along the z-axis as in homogeneous J c model. The mechanical response of stainless steel reinforced GdBCO bulk was aslo simulated and analyzed. Finally, the coupling effect between the fracture strength variability caused by defects and cracks and the trapped field in GdBCO bulks with r-z plane J c inhomogeneity is further studied. This study may provide a relatively realistic mechanical response of HTS bulk during FCM, and a novel design consideration for its mechanical reinforcement.

Polycaprolactone-Li6PS5Cl composite polymer electrolytes for stable room temperature all-solid-state lithium batteries

Incorporating inorganic fillers into solid polymer electrolytes (SPEs) to construct composite polymer electrolytes (CPEs) serves as an effective strategy to comprehensively enhance the properties of solid electrolytes. Herein, a CPE is fabricated by integrating Li6PS5Cl particles into polycaprolactone (PCL). The addition of active fillers could effectively weaken the crystallization of polymer and increase the ionic conductivity of the solid electrolyte. In particular, the PCL-based polymer electrolyte with 3% Li6PS5Cl (PCL-3) exhibits an excellent ionic conductivity of 1.36×10−4 S cm−1 at room temperature, which is one order higher than that of PCL polymer solid electrolyte. And it achieves a high critical current density of 2.2 mA cm−2 with a capacity of 2.2 mAh cm−2. The assembled Li symmetric battery can cycle steadily for more than 3000 h at 0.5 mA cm−2 under room temperature. The LiFePO4/PCL-3/Li all-solid-state battery maintains a capacity of 125.3 mAh g−1 after 400 cycles at 0.2 C under room temperature. Notably, the LiFePO4//Li battery also shows stable cycling at 40 °C, exhibiting high reversible specific capacities of 156.7 mAh g−1 and 126.3 mAh g−1 with a retention rate of 97.15% and 94.6% at 0.2 C and 0.5 C after 100 cycles, respectively, showing promising application prospects for all-solid-state lithium metal batteries.

Built-in garnet-rich composite solid electrolyte towards fast ion transport and dendrite-free for high-energy lithium batteries

Composite solid-state electrolytes (CSEs), which could provide greater flexibility to harness the advantages of single-phase electrolytes, are promising candidates for solid-state lithium (Li) batteries. However, the agglomeration of inorganic phase obstructs the efficient ion-conduction channel and accelerates dendrite growth, limiting the practical application of CSEs. Herein, a flexible garnet-rich composite skeleton is prepared by incorporating well-dispersed Li6.4La3Zr1.4Ta0.6O12 (LLZTO) with robust polyimide scaffold through a simple method. Subsequently, a compact composite bi-phase electrolyte with abundant and well-dispersed built-in LLZTO could be attained via in-situ curing of a poly(ethylene glycol)diacrylate-based polymer electrolyte within this skeleton. Capitalizing on the rapid Li+ pathways contributed by the high fraction and well-distributed ceramic phase, this electrolyte demonstrates remarkably ionic conductivity and Li+ transference number of 0.95 mS cm−1 and 0.81, respectively. The deigned bi-phase composite enables a stable and uniform Li stripping/plating in symmetrical Li||Li batteries over 1000 h at 0.2 mA cm−2 and a high critical current density of 1.9 mA cm−2, facilitated by enhanced Li+ conduction dynamics and homogenous Li+ flux. LiNi0.8Co0.1Mn0.1O2||Li cells using this electrolyte exhibit favorable battery performances (159.8 mAh g−1, 96.4%@180 cycles, 0.5C). Furthermore, this scalable fabrication process for this composite electrolyte holds great potential in grid-scale production for safe and high-energy Li batteries.

Electromechanical behavior of a rectangular bulk superconductor with an inhomogeneous critical current density under pulsed-field magnetization

Bulk high-temperature superconductors are widely used in various superconducting devices for their high critical current density and the ability to trap large magnetic field. In some applications, bulk superconductors can be arranged in an array structure to increase the magnetic field strength. However, rectangular bulk superconductors can be arranged more compactly than commonly used cylindrical bulk superconductors. The unique shape of rectangular bulk superconductors results in different distributions of electromagnetic fields, temperature, and stress under a pulsed-field magnetization (PFM) than for cylindrical bulk superconductors. In bulk superconductors, growth sector boundaries and growth sector regions have different critical current density, resulting in an uneven critical current density. Therefore, in this study, the electromagnetic and mechanical behavior of non-uniform rectangular bulk superconductors during the PFM process is investigated. The corresponding distribution and variation in the magnetic field, current, temperature, and stress in the bulk are calculated and analyzed. The influence of rectangle aspect ratio on the electromagnetic and mechanical behavior is discussed. The calculation results show that the magnetic flux jumps occur accompanied by sudden changes in the temperature and pressure. The effect of the aspect ratio of rectangular bulk superconductors on their electromagnetic and mechanical properties is analyzed. The influence of preexisting cracks in a non-uniform rectangular bulk superconductor on the simulation results is discussed. The numerical results indicate that the presence of an edge crack exacerbates the magnetic flux jump as well as the jumps in the temperature and stress. However, a central crack has a relatively small effect on the stability of a bulk superconductor.