Highest Room Temperature Conductivity Research Articles

Enhancing ion conductivity in polyethylene oxide-based polymers through semi-interpenetrating networks with liquid crystalline polymer for lithium metal batteries

Solid electrolytes play a pivotal role in these batteries but are hindered by challenges such as low ion conductivity and inadequate mechanical properties. In this study, a synergistic multi-component system was fabricated using a microphase separation technique to integrate liquid crystal polymers with self-assembly characteristics and polyethylene oxide (PEO) known for its excellent ion transport performance. Molecular-level control was achieved by adjusting the ratio of liquid crystal monomers, facilitating the construction of ordered ion transport pathways that significantly enhance room temperature ion transport efficiency. The resulting solid polymer electrolyte adopts a semi-interpenetrating network structure, where the rigid framework of liquid crystalline polymers is interpenetrated with flexible PEO chains. It exhibits a high room-temperature ion conductivity of 4.7 × 10−4 S/cm and a lithium-ion migration number of 0.71. Benefitting from its tailored microstructure and mechanical properties, the assembled lithium symmetric battery demonstrated stable operation over 2800 h at a room temperature current density of 0.1 mA/cm−2. This research presents a promising pathway for the advancement of advanced electrolyte materials, providing valuable insights into improving the efficiency and safety of lithium metal batteries in practical applications.

Superionic lithium argyrodite-type sulfide electrolyte with optimized composite cathode fabrication enabling stable All-Solid-State Batteries

All-solid-state batteries (ASSBs) are promising candidates for next-generation energy storage devices. However, several key aspects especially superionic solid electrolytes (SEs) and carefully designed electrode configurations still remain a challenge for the development of high performance ASSBs. Herein, a halogen-rich lithium argyrodite, Li5.5PS4.5Cl0.8Br0.7 (LPSCB) with optimized synthesis condition is successfully prepared. Electrochemical impedance spectroscopy and X-ray diffraction illustrate that annealing temperature affects Li-ion dynamics, which guides the formation of LPSCB with a high room-temperature ionic conductivity of 10.7 mS cm−1. Furthermore, LiNi0.9Co0.05Mn0.05O2 with ZrO2 dual-functional coating layer (ZrO2@NCM) was introduced as cathode active materials (CAMs) to guarantee high-energy-density composite cathode. Correspondingly, a better understanding of the optimization of composite cathode design based on the superionic LPSCB is well elucidated and fast ion/electron transport is achieved by revealing the effect of different CAM fractions in the cathodes on the rate and cycling performance. Specifically, ASSBs with 60 wt.% and 80 wt.% CAM deliver high discharge capacity of 1.1 and 1.95 mAh cm−2 at −20 °C and 60 °C, with corresponding capacity retention of 86.4 % and 69.7 % after 100 and 150 cycles, respectively. This work demonstrates the necessity of customizing CAM fractions depending on the desired applications of ASSBs, and provides an effective cathode modification strategy toward the development of sulfide-based ASSBs with excellent electrochemical performance.

Scalable Synthesis and Electrochemical Study of Ceramic-Polymer Nanocomposite Solid Electrolytes for Solid-State Battery Manufacturing

Solid-state lithium batteries (SSBs) have the potential to achieve high energy and power densities due to the use of solid electrolytes (SEs) that are compatible with lithium metal or silicon-based anodes. However, fabrication of SEs with good ionic conductivity, mechanical strength, electrochemical stability, and interfacial contact with solid electrodes have been challenging. One promising approach is to combine ceramic lithium conductors that is expected to show a relatively high room-temperature Li-ion conductivity and a soft polymer matrix that facilitates mechanical integrity at the electrode-electrolyte interface during charge-discharge cycling. In this study, we report a scalable synthesis of Al0.25Li6.25La3Zr2O12 (LLZO) nanofibers and polyethylene oxide (PEO) composite SEs using roll-to-roll manufacturing. Our LLZO fibers showed 0.3 mS/cm conductivity at room temperature and the LLZO-PEO composites showed three times higher critical current density than a single PEO polymer electrolyte. Microstructural and electrochemical properties of the composite electrolytes will be discussed.

Giant dielectric ceramic of Li0.3Ti0.02Ni0.68O with abundant oxygen vacancies enabling high lithium-ion conductivity in composite solid-state electrolyte

The low ionic conductivity of composite solid-state electrolytes due to the lack of free Li-ions and Li dendrite growth induced by the low transference number seriously hinder their application. Herein, we find that the giant dielectric ceramic of Li0.3Ti0.02Ni0.68O (LTNO) with ultra-high dielectric constant can greatly promote the dissociation of Li salt to generate abundant movable Li-ions and realize a high room-temperature ionic conductivity (4.09 × 10–4 S cm−1) as well as a low activation energy (0.16 eV). The oxygen vacancies on the surface of LTNO can effectively immobilize the anions to achieve a high Li transference number (0.61). Furthermore, the enhanced dielectric properties of the composite electrolyte induce homogenous Li plating/stripping to suppress the growth of Li dendrites. As a result, the Li||Li symmetric cells exhibit long lifespan of 2400 h and 1150 h at 0.1 mA cm−2 and 0.2 mA cm−2, respectively. The Li||LiNi0.8Co0.1Mn0.1O2 solid-state full cells show a high capacity retention of 83% after 430 cycles at 2C. This work highlights the critical role of high dielectric property and oxygen defects of fillers in composite solid-state electrolytes, and provides a demonstration for the application of giant dielectric materials in solid-state Li metal batteries.

Superionic Conduction in K3SbS4 Enabled by Cl-Modified Anion Lattice.

All-solid-state potassium batteries emerge as promising alternatives to lithium batteries, leveraging their high natural abundance and cost-effectiveness. Developing potassium solid electrolytes (SEs) with high room-temperature ionic conductivity is critical for realizing efficient potassium batteries. In this study, we present the synthesis of K2.98Sb0.91S3.53Cl0.47, showcasing a room-temperature ionic conductivity of 0.32 mS/cm and a low activation energy of 0.26 eV. This represents an increase of over two orders of magnitude compared to the parent compound K3SbS4, marking the highest reported ionic conductivity for non-oxide potassium SEs. Solid-state 39K magic-angle-spinning nuclear magnetic resonance on K2.98Sb0.91S3.53Cl0.47 reveals an increased population of mobile K+ ions with fast dynamics. Ab initio molecular dynamics (AIMD) simulations further confirm a delocalized K+ density and significantly enhanced K+ diffusion. This work demonstrates diversification of the anion sublattice as an effective approach to enhance ion transport and highlights K2.98Sb0.91S3.53Cl0.47 as a promising SE for all-solid-state potassium batteries.

Earth-Abundant Kaolinite Nanoplatelet Gel Electrolytes for Solid-State Lithium Metal Batteries.

Lithium-ion batteries are the leading energy storage technology for portable electronics and vehicle electrification. However, demands for enhanced energy density, safety, and scalability necessitate solid-state alternatives to traditional liquid electrolytes. Moreover, the rapidly increasing utilization of lithium-ion batteries further requires that next-generation electrolytes are derived from earth-abundant raw materials in order to minimize supply chain and environmental concerns. Toward these ends, clay-based nanocomposite electrolytes hold significant promise since they utilize earth-abundant materials that possess superlative mechanical, thermal, and electrochemical stability, which suggests their compatibility with energy-dense lithium metal anodes. Despite these advantages, nanocomposite electrolytes rarely employ kaolinite, the most abundant variety of clay, due to strong interlayer interactions that have historically precluded efficient exfoliation of kaolinite. Overcoming this limitation, here we demonstrate a scalable liquid-phase exfoliation process that produces kaolinite nanoplatelets (KNPs) with high gravimetric surface area, thus enabling the formation of mechanically robust nanocomposites. In particular, KNPs are combined with a succinonitrile (SN) liquid electrolyte to form a nanocomposite gel electrolyte with high room-temperature ionic conductivity (1 mS cm-1), stiff storage modulus (>10 MPa), wide electrochemical stability window (4.5 V vs Li/Li+), and excellent thermal stability (>100 °C). The resulting KNP-SN nanocomposite gel electrolyte is shown to be suitable for high-rate rechargeable lithium metal batteries that employ high-voltage LiNi0.8Co0.15Al0.05O2 (NCA) cathodes. While the primary focus here is on solid-state batteries, our strategy for kaolinite liquid-phase exfoliation can serve as a scalable manufacturing platform for a wide variety of other kaolinite-based nanocomposite applications.

Development of a new class of stable and adaptable free-standing fibre mats with high room-temperature hydroxide-ion conductivity

For alkaline anion-exchange membrane electrolysers and fuel cells to become a technological reality, hydroxide-ion (OH−) conducting membranes that are flexible, robust, affording high OH− conductivity, and synthesised in a low-cost and scalable way must be developed. In this paper, we engineer a stable, self-supporting, and flexible fibre mat using a low-cost ZIF-8 metal–organic framework composited with ionic liquid tetrabutylammonium hydroxide and widely used polyacrylonitrile as polymeric backbone. We obtain mats with a high intrinsic OH− conductivity for a metal–organic framework-based material already at room temperature, without added ion-conductor polymers. This approach will contribute to the development of low-cost and tuneable ion-conducting membranes.

The synergistic effect of Zn2+ doping and NaF interfacial melting aid increases the ionic conductivity of Na3Zr2Si2.2P0.8O12

All-solid-state sodium batteries, renowned for their leak-proof nature and enhanced safety profile, have become a pivotal focus of research. Their viability hinges on the development of robust solid electrolyte materials. Among these, Na3Zr2Si2PO12 (NZSP) stands out as a particularly promising candidate. However, the practical utility of NZSP has been limited by its relatively modest room temperature conductivity. This paper introduces a novel modification strategy aimed at significantly enhancing room temperature conductivity of NZSP. In the series of experiments, NSZP was synthesized by traditional sintering process with Zn2+ doping and NaF additives. Through the substitution of Zr4+ ions with Zn2+ ions, this innovative approach not only raises the sodium ion concentration but also expands the bottleneck regions within the Na ion transport pathways. This augmentation ultimately translates into heightened grain conductivity. Additionally, the incorporation of NaF during the sintering process induces crystal growth in NZSP, thereby reducing grain boundary concentration and further amplifying grain conductivity's contribution to the overall ionic conductivity. Employing conventional sintering techniques, we successfully synthesized Na3.3Zr1.95Zn0.05Si2.2P0.8O12-0.25NaF (−0.25 NaF indicates that 0.25 mol NaF was added during sintering) electrolyte samples, which demonstrated an impressive high room temperature conductivity of 2.2 × 10−3 S cm−1. This value surpasses the ionic conductivity of undoped NZSP electrolytes by approximately an order of magnitude. Moreover, the Na3.3Zr1.95Zn0.05Si2.2P0.8O12-0.25NaF electrolyte exhibits a remarkable electrochemical window extending up to 4.9 V, accompanied by exceptional cycling stability. These properties render it an ideal candidate for a diverse array of cathode materials.

Solvation engineering of non-aqueous electrolytes for room-temperature fluoride-ion batteries

Fluoride-ion batteries (FIBs) with high energy density and low cost are a promising new generation battery system for renewable energy storage. However, their room-temperature operation is strongly impeded by the lack of compatible electrolytes. Herein, we demonstrate that a stable room-temperature FIB can be achieved by tailoring the solvation chemistry of a non-aqueous liquid electrolyte. As validated by computational modeling and spectroscopic investigations, the cost-efficient β-hydrogen-free tetramethylammonium fluoride (TMAF) salt can efficiently prevent Hofmann elimination-induced electrolyte decomposition. Meanwhile, the synergistic effect of strong-polarity solvent and anion acceptor additive endows the high salt solubility (up to 0.7 M) and room-temperature ionic conductivity (6.12×10−3 S cm−1 at 25 °C) for the electrolyte. Owing to the virtue of this new electrolyte design, the Zn||CuF2 and Li||CuF2 FIBs were successfully constructed, delivering high reversibility, stable interface, and extended life. This work offers a new pathway for clearing the formidable bottlenecks in developing high-performance Fluoride-ion batteries.

In situ polymerization design of a quasi-solid electrolyte enhanced by NMP additive for lithium metal batteries

Solid polymer electrolytes (SPEs) are considered one promising candidate for lithium metal batteries due to their high flexibility, low cost, and roll-to-roll scalability. However, conventional SPEs prepared via ex situ methods are confronted with challenges such as poor contact and high resistance at the electrode|SPE interface, as well as low ionic conductivity at room temperature. In this study, we developed a quasi-solid electrolyte (QSE) using an in situ polymerization approach, employing butyl acrylate as the monomer and incorporating NMP as an additive. Spectroscopic investigations and DFT calculations revealed that NMP tends to form an overleaf-structured [Li(NMP)3][TFSI] complex with LiTFSI, promoting lithium salt dissociation. Owing to this advantage, the QSE exhibits high room-temperature ionic conductivity (6.94 × 10−4 S cm−1) and an extensive electrochemical stability window (5.01 V vs. Li+/Li). Furthermore, the in situ polymerization method facilitates full contact at the interface, enhancing the interfacial stability and reducing the interface resistance, thus resulting in stable cycling of Li|Built-in QSE|Li symmetric cell for 1100 h at 0.1 mA cm−2. The assembled LiFePO4|Built-in QSE|Li cell also demonstrates excellent rate and long-term cycling performance. Our findings offer valuable insights into the interaction between organic additives and lithium salts and present a novel strategy for the development of polymer electrolytes.

Ultrathin, Mechanically Durable, and Scalable Polymer-in-Salt Solid Electrolyte for High-Rate Lithium Metal Batteries.

Polymer-in-salt solid-state electrolytes (PIS SSEs) are emerging for high room-temperature ionic conductivity and facile handling, but suffer from poor mechanical durability and large thickness. Here, Al2O3-coated PE (PE/AO) separators are proposed as robust and large-scale substrates to trim the thickness of PIS SSEs without compromising mechanical durability. Various characterizations unravel that introducing Al2O3 coating on PE separators efficiently improves the wettability, thermal stability, and Li-dendrite resistance of PIS SSEs. The resulting PE/AO@PIS demonstrates ultra-small thickness (25µm), exceptional mechanical durability (55.1MPa), high decomposition temperature (330°C), and favorable ionic conductivity (0.12 mS cm-1 at 25°C). Consequently, the symmetrical Li cells remain stable at 0.1mA cm-2 for 3000 h, without Li dendrite formation. Besides, the LiFePO4|Li full cells showcase excellent rate capability (131.0 mAh g-1 at 10C) and cyclability (93.6% capacity retention at 2C after 400 cycles), and high-mass-loading performance (7.5mg cm-2). Moreover, the PE/AO@PIS can also pair with nickel-rich layered oxides (NCM811 and NCM9055), showing a remarkable specific capacity of 165.3 and 175.4 mAh g-1 at 0.2C after 100 cycles, respectively. This work presents an effective large-scale preparation approach for mechanically durable and ultrathin PIS SSEs, driving their practical applications for next-generation solid-state Li-metal batteries.

A solid-state lithium-ion battery with micron-sized silicon anode operating free from external pressure

Applying high stack pressure (often up to tens of megapascals) to solid-state Li-ion batteries is primarily done to address the issues of internal voids formation and subsequent Li-ion transport blockage within the solid electrode due to volume changes. Whereas, redundant pressurizing devices lower the energy density of batteries and raise the cost. Herein, a mechanical optimization strategy involving elastic electrolyte is proposed for SSBs operating without external pressurizing, but relying solely on the built-in pressure of cells. We combine soft-rigid dual monomer copolymer with deep eutectic mixture to design an elastic solid electrolyte, which exhibits not only high stretchability and deformation recovery capability but also high room-temperature Li-ion conductivity of 2×10−3 S cm−1 and nonflammability. The micron-sized Si anode without additional stack pressure, paired with the elastic electrolyte, exhibits exceptional stability for 300 cycles with 90.8% capacity retention. Furthermore, the solid Li/elastic electrolyte/LiFePO4 battery delivers 143.3 mAh g−1 after 400 cycles. Finally, the micron-sized Si/elastic electrolyte/LiFePO4 full cell operates stably for 100 cycles in the absence of any additional pressure, maintaining a capacity retention rate of 98.3%. This significantly advances the practical applications of solid-state batteries.

Economical sodium source prepared Na3SbS4 electrolyte with improved electrochemical performance by La doping

Solid electrolytes are expected to improve the next-generation rechargeable batteries in terms of safety and cost issues. In the present study, we designed a conventional sulfide sodium-ion conductor Na3+2xLaxSb1-xS4 synthesized from Na2S·9H2O as raw material. For optimized electrochemical behavior, the partial substitution of Sb with La in Na3SbS4 was modified by broadening Na+ ion channels and increasing interstitial Na+ ions in the network lattice. The structural characterization verified the increase in crystallinity after subsequent heating at 450 °C. The composition and structural design realized a high room temperature conductivity of 0.52 mS cm−1 and low activation energy of 0.069 eV for the Na3·1La0·05Sb0·95S4 sample. Moreover, this sulfide electrolyte was equipped with additional advantages, such as much lower electronic conductivity than Na3SbS4 and air stability against the humid atmosphere.

A Fluoride-Rich Solid-Like Electrolyte Stabilizing Lithium Metal Batteries.

To address the problems associated with Li metal anodes, a fluoride-rich solid-like electrolyte (SLE) that combines the benefits of solid-state and liquid electrolytes is presented. Its unique triflate-group-enhanced frame channels facilitate the formation of a functional inorganic-rich solid electrolyte interphase (SEI), which not only improves the reversibility and interfacial charge transfer of Li anodes but also ensures uniform and compact Li deposition. Furthermore, these triflate groups contribute to the decoupling of Li+ and provide hopping sites for rapid Li+ transport, enabling a high room-temperature ionic conductivity of 1.1 mS cm-1 and a low activation energy of 0.17eV, making it comparable to conventional liquid electrolytes. Consequently, Li symmetric cells using such SLE achieve extremely stable plating/stripping cycling over 3500h at 0.5mA cm-2 and support a high critical current up to 2mA cm-2. The assembled Li||LiFePO4 solid-like batteries exhibit exceptional cyclability for over 1 year and a half, even outperforming liquid cells. Additionally, high-voltage cylindrical cells and high-capacity pouch cells are demonstrated, corroborating much simpler processibility in battery assembly compared to all-solid-state batteries.

In situ polymerization of 1,3-dioxolane and formation of fluorine/boron-rich interfaces enabled by film-forming additives for long-life lithium metal batteries.

In situ polymerized 1,3-dioxolane (PDOL) is widely utilized to construct solid polymer electrolytes because of its high room-temperature ionic conductivity and good compatibility with lithium metal. However, the current polymerization additives used in PDOL do not effectively contribute to the formation of a robust solid electrolyte interphase (SEI), leading to decreased cycle life. Herein, a film-forming Lewis acid, tris(hexafluoroisopropyl) borate (THB), is demonstrated not only to be a catalyst for the ring-opening polymerization of DOL, but also an additive for the formation of a stable fluorine- and boron-rich SEI to improve the interfacial stability and suppress the Li dendrite growth. Moreover, molecular dynamics simulations and experimental results demonstrate that the introduction of THB can promote the dissociation of lithium salt and release more Li+ while the boron site can effectively restrict the free movement of TFSI- anion, thus increasing Li+ transference numbers (0.76) and ensuring the long-term cycling stability of cells. By using THB-PDOL, a stable cycling of Li‖Li symmetric cell for 600 h at a capacity of 0.5 mA h cm-2 can be achieved. Furthermore, employing THB-PDOL in Li‖LiFePO4 full cell enables a capacity retention of 98.64% after 300 cycles at 1C and a capacity retention of 95.39% after 200 cycles at a high temperature (60 °C). At the same time, this electrolyte is also suitable for the Li‖NCM523 full cell, which also achieves excellent stability of more than 180 cycles. This film-forming Lewis acid additive provides ideas for designing low-cost, high-performance PDOL-based lithium metal batteries.

Ion-conductive vs. non-ion-conductive ceramic fillers in silane-linked polyethylene oxide-based composite polymer electrolytes with high room-temperature ionic conductivity

Polyethylene oxide (PEO)-based polymer electrolytes, despite their cost-effectiveness and ease of processing, suffer from low ionic conductivity at lower temperatures due to the semi-crystalline nature of PEO. Incorporating ceramic filler...

(Invited) Overview of Ionic Liquid Electrolytes Doped with δ-Metal Halides for Advanced Post-Lithium-Ion Batteries

Humankind is currently facing a global transition towards a green electrification of both energy production and transportation. There is an urgent need to find new approaches for the storage of energy derived from renewable sources, such as solar irradiation, wind and waves. In addition, electric cars require energy storage or conversion systems capable of providing engine power. To these ends, secondary batteries are an attractive and viable solution, especially in the form of the relatively mature Li-ion technology. Unfortunately, Li power sources suffer from high cost, low Li earth-crust abundance, and toxicity of their electrochemical components (e.g., the Co-based cathodes). Such disadvantages demand the exploration of new energy storage devices based on alternative chemistries (e.g., Na, Mg, Ca).Since their discovery [1-5], electrolytes based on disordered or delta metal halide salts (e.g., δ-MgCl2, δ-LiCl, δ-MgI2) have received widespread attention due to their intriguing physical-chemical properties. Subsequently, electrolytes comprised of ionic liquid solvents dispersing various δ-metal halide salts were investigated [6-9]. These latter ion-conducting systems are characterized by: (i) very high room-temperature ionic conductivity; (ii) wide thermal, chemical and electrochemical stability; and (iii) high coulombic efficiency and very low overpotentials in the metal deposition and stripping processes.In this contribution, a comparison of different families of ionic liquids will be proposed. In particular, the effects of the use of δ-metal halide salts (e.g., δ-MgCl2, δ-LiCl, and δ-NaCl) on the thermal stability, vibrational features, and electrochemical properties of the resulting electrolytes will be considered. The conductivity mechanisms will be analyzed side-by-side, revealing how ionic conductivity is modulated by the metal ions (e.g., Mg2+, Li+, Na+), on the basis of broadband electrical spectroscopy results. Acknowledgments The authors acknowledge support in the form of the following grants: project “Interplay between structure, properties, relaxations and conductivity mechanism in new electrolytes for secondary Magnesium batteries” (Grant Agreement W911NF-21-1-0347-(78622-CH-INT)) of the U.S. Army Research Office; project “ACHILLES” (prot. BIRD219831) of the University of Padua; project “VIDICAT” (Grant Agreement 829145) of the FET-Open call of Horizon 2020; project “Polymer electrolytes for Sodium Batteries” (Grant Agreement 72957-00 01) sponsored by Natrion Inc. and the CUNY Sensor CAT.

NASICON-type Ta5+ substituted LiZr2(PO4)3 with improved ionic conductivity as a prospective solid electrolyte

The need to develop safe solid-state lithium batteries has stimulated intense research efforts for Li+ solid electrolytes. However, the low conductivity limits the development of NASICON LiZr2(PO4)3 (LZP) electrolyte. Here, the doping effects of Ta on the structure, surface morphologies and electrochemical properties of Li1-xZr2-xTax(PO4)3 (LZTP, x = 0, 0.01, 0.02, 0.04, 0.06 and 0.08) solid electrolyte were analyzed. LZTP was prepared using a simple solid-state reaction route, followed by sintering at 1200 °C for 12 h. A proper content of Ta5+ substitution for Zr4+ is beneficial to stabilize the high conductive rhombohedral (α) phase of LZP at room temperature. Doping Ta5+ is conducive to unblocking of Li+ at the M1 site and facilitates the occupation of Li+ at the M2 site, thereby expanding the pathway for Li+ conduction. Rietveld refinement data demonstrated that the Zr–O and P–O bond lengths (dZr-O and dP-O) increased with a decrease in Zr–O–P bond angles (θZr-O-P) as x rose. The distortions in the ZrO6 octahedron may weaken the coulomb attraction in Li+-O2-, resulting in a lower activation energy (Ea) and a higher Li+ conductivity. The highest room-temperature conductivity (6.06 × 10−5 S cm−1) was obtained at x = 0.06, which reached 1.5 × 10−4 S cm−1 at 50 °C. The Ea was found to decrease from 0.388 eV (x = 0) to 0.306 eV (x = 0.06). In addition, Ta doping resulted in improved connectivity and reduced pore formation, which also contributed to the decrease in resistance. The Raman spectrum demonstrated that some phonon modes of bending vibration in PO4 were degenerate and external modes became too weak to be observed or even disappeared as Ta content increased. This change in the modes also had an impact on the Li+ conductivity. Overall, the LZTP-0.06 appears to be a promising candidate for the solid electrolyte.

A flux growth technique for high quality cubic boron arsenide bulk single crystals

The growth of single crystal cubic boron arsenide (c-BAs) has attracted considerable interest due to its high room-temperature thermal conductivity and high ambipolar electrical mobility. However, currently the only growth technique reported for c-BAs crystals is the chemical vapor transport (CVT) method, which exhibits several drawbacks with regard to size scalability and crystal quality control, thereby hindering the further advancement of this semiconductor material. Herein, we report a flux growth technique using liquid arsenic (l-As) as a reaction medium at high pressures for the growth of high-quality c-BAs crystals with several millimeters size. The outstanding properties, including high uniformity, lower defect density, and lower carrier concentration of the as-grown c-BAs single crystals from flux growth, have been verified via a combination of techniques including x-ray diffraction, Raman scattering, photoluminescence spectroscopy, and electrical transport measurements, in comparison with the CVT-grown crystals.

The Universal Super Cation-Conductivity in Multiple-cation Mixed Chloride Solid-State Electrolytes.

As exciting candidates for next-generation energy storage, all-solid-state lithium batteries (ASSLBs) are highly dependent on advanced solid-state electrolytes (SSEs). Here, using cost-effective LaCl3 and CeCl3 lattice (UCl3 -type structure) as the host and further combined with a multiple-cation mixed strategy, we report a series of UCl3 -type SSEs with high room-temperature ionic conductivities over 10-3 S cm-1 and good compatibility with high-voltage oxide cathodes. The intrinsic large-size hexagonal one-dimensional channels and highly disordered amorphous phase induced by multi-metal cation species are believed to trigger fast multiple ionic conductions of Li+ , Na+ , K+ , Cu+ , and Ag+ . The UCl3 -type SSEs enable a stable prototype ASSLB capable of over 3000 cycles and high reversibility at -30 °C. Further exploration of the brand-new multiple-cation mixed chlorides is likely to lead to the development of advanced halide SSEs suitable for ASSLBs with high energy density.