Tetraarylborate polymer networks as single-ion conducting solid electrolytes

A new family of solid polymer electrolytes based upon anionic tetrakis(phenyl)borate tetrahedral nodes and linear bis-alkyne linkers is reported. Sonogashira polymerizations using tetrakis(4-iodophenyl)borate, tetrakis(4-iodo-2,3,5,6-tetrafluorophenyl)borate and tetrakis(4-bromo-2,3,5,6-tetrafluorophenyl)borate delivered highly cross-linked polymer networks with both 1,4-diethynylbeznene and a tri(ethylene glycol) substituted derivative. Promising initial conductivity metrics have been observed, including high room temperature conductivities (up to 2.7 × 10^–4 S cm^–1), moderate activation energies (0.25–0.28 eV), and high lithium ion transport numbers (up to t _Li⁺ = 0.93). Initial investigations into the effects of important materials parameters such as bulk morphology, porosity, fluorination, and other chemical modification, provide starting design parameters for further development of this new class of solid electrolytes.     

Enhanced Surface Interactions Enable Fast Li+ Conduction in Oxide/Polymer Composite Electrolyte

Li⁺‐conducting oxides are considered better ceramic fillers than Li⁺‐insulating oxides for improving Li⁺ conductivity in composite polymer electrolytes owing to their ability to conduct Li⁺ through the ceramic oxide as well as across the oxide/polymer interface. Here we use two Li⁺‐insulating oxides (fluorite Gd_0.1Ce_0.9O_1.95 and perovskite La_0.8Sr_0.2Ga_0.8Mg_0.2O_2.55) with a high concentration of oxygen vacancies to demonstrate two oxide/poly(ethylene oxide) (PEO)‐based polymer composite electrolytes, each with a Li⁺ conductivity above 10^?4 S cm^?1 at 30 °C. Li solid‐state NMR results show an increase in Li⁺ ions (>10 %) occupying the more mobile A2 environment in the composite electrolytes. This increase in A2‐site occupancy originates from the strong interaction between the O^2? of Li‐salt anion and the surface oxygen vacancies of each oxide and contributes to the more facile Li⁺ transport. All‐solid‐state Li‐metal cells with these composite electrolytes demonstrate a small interfacial resistance with good cycling performance at 35 °C.     

Proton-conductive coordination polymer glass for solid-state anhydrous proton batteries

Designing solid-state electrolytes for proton batteries at moderate temperatures is challenging as most solid-state proton conductors suffer from poor moldability and thermal stability. Crystal–glass transformation of coordination polymers (CPs) and metal–organic frameworks (MOFs) via melt-quenching offers diverse accessibility to unique properties as well as processing abilities. Here, we synthesized a glassy-state CP, [Zn₃(H₂PO₄)₆(H₂O)₃](1,2,3-benzotriazole), that exhibited a low melting temperature (114 °C) and a high anhydrous single-ion proton conductivity (8.0 × 10⁻³ S cm⁻¹ at 120 °C). Converting crystalline CPs to their glassy-state counterparts via melt-quenching not only initiated an isotropic disordered domain that enhanced H⁺ dynamics, but also generated an immersive interface that was beneficial for solid electrolyte applications. Finally, we demonstrated the first example of a rechargeable all-solid-state H⁺ battery utilizing the new glassy-state CP, which exhibited a wide operating-temperature range of 25 to 110 °C.

Melt-quenched coordination polymer glass shows exclusive H⁺ conductivity (8.0 × 10⁻³ S cm⁻¹ at 120 °C, anhydrous) and optimal mechanical properties (42.8 Pa s at 120 °C), enables the operation of an all-solid-state proton battery from RT to 110 °C.     

SnO2 Quantum Dots Distributed along V2O5 Nanobelts for Utilization as a High-Capacity Storage Hybrid Material in Li-Ion Batteries

In this study, the facile synthesis of SnO₂ quantum dot (QD)-garnished V₂O₅ nanobelts exhibiting significantly enhanced reversible capacity and outstanding cyclic stability for Li⁺ storage was achieved. Electrochemical impedance analysis revealed strong charge transfer kinetics related to that of V₂O₅ nanobelts. The SnO₂ QD-garnished V₂O₅ nanobelts exhibited the highest discharge capacity of ca. 760 mAhg⁻¹ at a density of 441 mAg⁻¹ between the voltage ranges of 0.0 to 3.0 V, while the pristine V₂O₅ nanobelts samples recorded a discharge capacity of ca. 403 mAhg⁻¹. The high capacity of QD-garnished nanobelts was achieved as an outcome of their huge surface area of 50.49 m²g⁻¹ and improved electronic conductivity. Therefore, the as-presented SnO₂ QD-garnished V₂O₅ nanobelts synthesis strategy could produce an ideal material for application in high-performance Li-ion batteries.     

Syntheses and Characterization of Novel Perovskite-Type LaScO3-Based Lithium Ionic Conductors

Perovskite-type lithium ionic conductors were explored in the (Li_xLa_1−x/3)ScO₃ system following their syntheses via a high-pressure solid-state reaction. Phase identification indicated that a solid solution with a perovskite-type structure was formed in the range 0 ≤ x < 0.6. When x = 0.45, (Li_0.45La_0.85)ScO₃ exhibited the highest ionic conductivity and a low activation energy. Increasing the loading of lithium as an ionic diffusion carrier expanded the unit cell volume and contributed to the higher ionic conductivity and lower activation energy. Cations with higher oxidation numbers were introduced into the A/B sites to improve the ionic conductivity. Ce⁴⁺ and Zr⁴⁺ or Nb⁵⁺ dopants partially substituted the A-site (La/Li) and B-site Sc, respectively. Although B-site doping produced a lower ionic conductivity, A-site Ce⁴⁺ doping improved the conductive properties. A perovskite-type single phase was obtained for (Li_0.45La_0.78Ce_0.05)ScO₃ upon Ce⁴⁺ doping, providing a higher ionic conductivity than (Li_0.45La_0.85)ScO₃. Compositional analysis and crystal-structure refinement of (Li_0.45La_0.85)ScO₃ and (Li_0.45La_0.78Ce_0.05)ScO₃ revealed increased lithium contents and expansion of the unit cell upon Ce⁴⁺ co-doping. The highest ionic conductivity of 1.1 × 10⁻³ S cm⁻¹ at 623 K was confirmed for (Li_0.4Ce_0.15La_0.67)ScO₃, which is more than one order of magnitude higher than that of the (Li_xLa_1−x/3)ScO₃ system.     

Raman and infrared spectra of6Li2C2O4 and7Li2C2O4

Raman and infrared spectra of polycrystalline⁶Li₂C₂O₄ and⁷Li₂C₂O₄ have been investigated in the wavenumber region from 1,800 to 40 cm^–1. The internal C₂O₄ ^–2 vibrations have been studied on the basis of a D_2h molecular structure and the correlation field splittings have been found to be about 40 cm^–1 for the stretching modes and about 15 cm^–1 for the bending modes. The external vibrations of the Li⁺ and C₂O₄ ^–2 sites have been discussed by considering the results of the factor group analysis and the⁶Li/⁷Li isotope effect on the normal vibrations.

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Raman- und Infrarot-Spektren von⁶Li₂C₂O₄ und⁷Li₂C₂O₄

Zusammenfassung Es wurdenRaman- und IR-Spektren von polykristallinem⁶Li₂C₂O₄ und⁷Li₂C₂O₄ im Bereich der Wellenzahlen von 1800 bis 40 cm^–1 untersucht. Die internen Schwingungen wurden auf der Basis einer D_2h Molekülstruktur analysiert. Für die Streckschwingungen wurde eine Korrelationsaufspaltung von etwa 40 cm^–1 gefunden, für die Deformationsschwingungen etwa 15 cm^–1. Die Diskussion der externen Schwingungen von Li⁺ und C₂O₄ ^–2 erfolgte unter Berücksichtigung der Resultate der Faktorgruppenanalyse und des⁶Li/⁷Li Isotopeneffekts auf die Normalschwingungen.

     

Lithium-conducting solid electrolytes of Li<Subscript>4</Subscript>GeO<Subscript>4</Subscript>-Li<Subscript>3</Subscript>PO<Subscript>4</Subscript> system with additions of zirconium ions

The effect of partial substitution of Zr⁴⁺ ions for Ge4+ ions in highly conducting lithium-cationic solid electrolyte Li_3.75Ge_0.75P_0.25O₄ is studied. It is found that the introduction of zirconium ions considerably raises the conductivity of basic electrolyte in the high-temperature range. For the optimal composition, the conductivity is 2.82 × 10⁻¹ S cm⁻¹ at 400°C and 1.55 S cm⁻¹ at 700°C. Possible reasons for the effects are discussed.     

Nanocomposite Polymer Electrolytes of Sodium Alginate and Montmorillonite Clay

Nanocomposite polymer electrolytes (NPEs) were synthesized using sodium alginate (Alg) and either sodium (SCa-3-Na⁺)- or lithium (SCa-3-Li⁺)-modified montmorillonite clays. The samples were characterized by structural, optical, and electrical properties. SCa-3-Na⁺ and SCa-3-Li⁺ clays’ X-ray structural analyses revealed peaks at 2θ = 7.2° and 6.7° that corresponded to the interlamellar distances of 12.3 and 12.8 Å, respectively. Alg-based NPEs X-ray diffractograms showed exfoliated structures for samples with low clay percentages. The increase of clay content promoted the formation of intercalated structures. Electrochemical Impedance Spectroscopy revealed that Alg-based NPEs with 5 wt% of SCa-3-Na⁺ clay presented the highest conductivity of 1.96 × 10⁻² S/cm², and Alg with 10 wt% of SCa-3-Li⁺ showed conductivity of 1.30 × 10⁻² S/cm², both measured at 70 °C. From UV-Vis spectroscopy, it was possible to infer that increasing concentration of clay promoted a decrease of the samples’ transmittance and, consequently, an increase of their reflectance.     

Structure,Luminescent Sensing and Proton Conduction of a Boiling-Water-Stable Zn(II) Metal-Organic Framework

A novel Zn(II) metal-organic framework [Zn₄O(C₃₀H₁₂F₄O₄S₈)₃]_n, namely ZnBPD-4F4TS, has been constructed from a fluoro- and thiophenethio-functionalized ligand 2,2′,5,5′-tetrafluoro-3,3′,6,6′-tetrakis(2-thiophenethio)-4,4′-biphenyl dicarboxylic acid (H₂BPD-4F4TS). ZnBPD-4F4TS shows a broad green emission around 520 nm in solid state luminescence, with a Commission International De L’Eclairage (CIE) coordinate at x = 0.264, y = 0.403. Since d¹⁰-configured Zn(II) is electrochemically inert, its photoluminescence is likely ascribed to ligand-based luminescence which originates from the well-conjugated system of phenyl and thiophenethio moieties. Its luminescent intensities diminish to different extents when exposed to various metal ions, indicating its potential as an optical sensor for detecting metal ion species. Furthermore, ZnBPD-4F4TS and its NH₄Br-loaded composite, NH₄Br@ZnBPD-4F4TS, were used for proton conduction measurements in different relative humidity (RH) levels and temperatures. Original ZnBPD-4F4TS shows a low proton conductivity of 9.47 × 10⁻¹⁰ S cm⁻¹ while NH₄Br@ZnBPD-4F4TS shows a more than 25,000-fold enhanced value of 2.38 × 10⁻⁵ S cm⁻¹ at 40 °C and 90% RH. Both of the proton transport processes in ZnBPD-4F4TS and NH₄Br@ZnBPD-4F4TS belong to the Grotthuss mechanism with E_a = 0.40 and 0.32 eV, respectively.     

Chemical states of tritium in solid lithium compounds irradiated with neutrons

Chemical states of tritium existing in neutron-irradiated solid lithium compounds were analyzed using a radiometric method. Nearly 100% of tritium was found in the T⁺ state in LiOH, Li₂O₂ and Li₃N, while the T^– state predominated in LiH, Li₇Pb₂ and Li₂C₂. Tritium incorporated in Li₂O, Li₂S, LiF, LiCl, LiBr and LiI was distributed over the T⁺, T^– and T⁰ states. In Li₂O crystals, the distribution of tritium in the T⁺ state increased from 58% to 81% with increasing neutron fluence from 2.5×10¹⁶ cm^–2 to 6.3×10¹⁷ cm^–2.     

Porous nanostructured V2O5 film electrode with excellent Li-ion intercalation properties

Porous nanostructured V₂O₅ films were prepared by electrodeposition from V₂O₅ sol with the addition of block copolymer Pluoronic P123, and they can be readily applied as Li-ion battery cathode without adding any polymer binder or conductive additives. SEM images showed an ideal morphology for Li⁺ intercalation favored charge transfer kinetics, which is a combination of homogeneously distributed nano-pores and V₂O₅ nanoparticles. Electrochemical measurements revealed that, the porous nanostructured V₂O₅ films have a high discharge capacity of 160 mAh/g at 9 A/g, and maintain 240 mAh/g after 40 cycles at 300 mA/g. The excellent Li⁺ intercalation property could be ascribed to the high surface area, sufficient contact between electrode materials and electrolyte, short Li⁺ diffusion path, as well as the good accommodation for volume change which are benefited from homogeneously distributed nano-pores and V₂O₅ nanoparticles.     

Li3PO4表面修饰提高球形LiNi0.5Mn1.5O4正极材料的性能

通过共沉淀法制备了球形LiNi_0.5Mn_1.5O₄@Li₃PO₄复合材料,并采用X射线衍射(XRD)、扫描电镜(SEM)、红外光谱(FT-IR)、循环伏安(CV)、电化学阻抗谱(EIS)及充放电测试研究了其结构与电化学性能。XRD和SEM表明,Li₃PO₄包覆影响了球形LiNi_0.5Mn_1.5O₄的晶格常数。CV和EIS表明,质量百分数5% Li₃PO₄包覆的LiNi_0.5Mn_1.5O₄具有比纯LiNi_0.5Mn_1.5O₄更高的锂离子嵌脱可逆性,更大的锂离子扩散系数和更小的电荷转移电阻,说明在锂离子扩散过程中,质量百分数5%Li₃PO₄包覆的LiNi_0.5Mn_1.5O₄具有更高的电子电导率。充放电测试表明,原位Li₃PO₄改性提高了材料的电子电导率、电化学活性,进而提高了高倍率放电容量。质量百分数5% Li₃PO₄包覆的LiNi_0.5Mn_1.5O₄提高的电化学性能归因于Li₃PO₄的包覆、纳米颗粒组成球形的粒径引起的高的电子电导率和小的电化学极化。     

Preparation and characterization of lithium ion-conducting glass-ceramics in the Li1 + xCrxGe2 − x(PO4)3 system

Li₂O–Cr₂O₃–GeO₂–P₂O₅ based glasses were synthesized by a conventional melt-quenching method and successfully converted into glass-ceramics through heat treatment. Experimental results of DTA, XRD, ac impedance techniques and FESEM indicated that Li_1.4Cr_0.4Ge_1.6(PO₄)₃ glass-ceramics treated at 900 °C for 12 h in the Li_1 + xCr_xGe_2 − x(PO₄)₃ (x = 0–0.8) system exhibited the best glass stability against crystallization and the highest ambient conductivity value of 6.81 × 10⁻⁴ S/cm with an activation energy as low as 26.9 kJ/mol. In addition, the Li_1.4Cr_0.4Ge_1.6(PO₄)₃ glass-ceramics displayed good chemical stability against lithium metal at room temperature. The good thermal and chemical stability, excellent conducting property, easy preparation and low cost make it promising to be used as solid-state electrolytes for all-solid-state lithium batteries.     

Ion polarisation-assisted hydrogen-bonded ferroelectrics in liquid crystalline domains

An alkylamide-substituted (−NHCOC₁₀H₂₁) hydrogen-bonded dibenzo[18]crown-6 derivative (1) was prepared to stabilise the ionic channel structure in a discotic hexagonal columnar (Col_h) liquid crystal. The introduction of simple M⁺X⁻ salts such as Na⁺PF₆⁻ and K⁺I⁻ into the ionic channel of 1 enhanced the ionic conductivity of the Col_h phase of the M⁺·(1)·X⁻ salts, with the highest ionic conductivity reaching ∼10⁻⁶ S cm⁻¹ for K⁺·(1)·I⁻ and Na⁺·(1)·PF₆⁻ at 460 K, which was approximately 5 orders of magnitude higher than that of 1. The introduction of non-ferroelectric 1 into the ferroelectric N,N′,N′′-tri(tetradecyl)-1,3,5-benzenetricarboxamide (3BC) elicited a ferroelectric response from the mixed Col_h phase of (3BC)_x(1)_1−x with x = 0.9 and 0.8. The further doping of M⁺X⁻ into the ferroelectric Col_h phase of (3BC)_0.9(1)_0.1 enhanced the ferroelectric polarisation assisted by ion displacement in the half-filled ionic channel for the vacant dibenzo[18]crown-6 of (3BC)_0.9[(M⁺)_0.5·(1)·(X⁻)_0.5]_0.1.

An alkylamide-substituted (−NHCOC₁₀H₂₁) hydrogen-bonded dibenzo[18]crown-6 derivative (1) was prepared to stabilise the ionic channel structure in a discotic hexagonal columnar (Col_h) liquid crystal.     

Defect Engineering and Anisotropic Modulation of Ionic Transport in Perovskite Solid Electrolyte LixLa(1−x)/3NbO3

Solid electrolytes, such as perovskite Li_3xLa_2/1−xTiO₃, Li_xLa_(1−x)/3NbO₃ and garnet Li₇La₃Zr₂O₁₂ ceramic oxides, have attracted extensive attention in lithium-ion battery research due to their good chemical stability and the improvability of their ionic conductivity with great potential in solid electrolyte battery applications. These solid oxides eliminate safety issues and cycling instability, which are common challenges in the current commercial lithium-ion batteries based on organic liquid electrolytes. However, in practical applications, structural disorders such as point defects and grain boundaries play a dominating role in the ionic transport of these solid electrolytes, where defect engineering to tailor or improve the ionic conductive property is still seldom reported. Here, we demonstrate a defect engineering approach to alter the ionic conductive channels in Li_xLa_(1−x)/3NbO₃ (x = 0.1~0.13) electrolytes based on the rearrangements of La sites through a quenching process. The changes in the occupancy and interstitial defects of La ions lead to anisotropic modulation of ionic conductivity with the increase in quenching temperatures. Our trial in this work on the defect engineering of quenched electrolytes will offer opportunities to optimize ionic conductivity and benefit the solid electrolyte battery applications.     

Synthesis and structure analysis of tetragonal Li7La3Zr2O12 with the garnet-related type structure

We have successfully synthesized a high-purity polycrystalline sample of tetragonal Li₇La₃Zr₂O₁₂. Single crystals have been also grown by a flux method. The single-crystal X-ray diffraction analysis verifies that tetragonal Li₇La₃Zr₂O₁₂ has the garnet-related type structure with a space group of I4₁/acd (no. 142). The lattice constants are a=13.134(4) Å and c=12.663(8) Å. The garnet-type framework structure is composed of two types of dodecahedral LaO₈ and octahedral ZrO₆. Li atoms occupy three crystallographic sites in the interstices of this framework structure, where Li(1), Li(2), and Li(3) atoms are located at the tetrahedral 8a site and the distorted octahedral 16f and 32g sites, respectively. The structure is also investigated by the Rietveld method with X-ray and neutron powder diffraction data. These diffraction patterns are identified as the tetragonal Li₇La₃Zr₂O₁₂ structure determined from the single-crystal data. The present tetragonal Li₇La₃Zr₂O₁₂ sample exhibits a bulk Li-ion conductivity of σ_b=1.63×10⁻⁶ S cm⁻¹ and grain-boundary Li-ion conductivity of σ_gb=5.59×10⁻⁷ S cm⁻¹ at 300 K. The activation energy is estimated to be E_a=0.54 eV in the temperature range of 300–560 K.     

Enabling ultrafast lithium-ion conductivity of Li2ZrCl6 by indium doping

Solid-state batteries with high energy density and safety are promising next-generation battery systems. However, lithium oxide and lithium sulfide electrolytes suffer low ionic conductivity and poor electrochemical stability, respectively. Lithium halide solid electrolyte shows high conductivity and good compatibility with the pristine high-voltage cathode but limited applications due to the high price of rare metal. Zr-based lithium halides with low cost and high stability possess great potential. Herein, a small amount of In³⁺ is introduced in Li₂ZrCl₆ to synthesize Li_2.25Zr_0.75In_0.25Cl₆ electrolytes with a high room temperature Li-ion conductivity of 1.08 mS/cm. Solid-state batteries using Li_2.25Zr_0.75In_0.25Cl₆/Li_5.5PS_4.5Cl_1.5 bilayer solid electrolytes combined with Li-In anode and pristine LiNi_0.7Mn_0.2Co_0.1O₂ cathode deliver high initial discharge capacities under different cut-off voltages. This work provides an effective strategy for enhancing the conductivity of Li₂ZrCl₆ electrolytes, promoting their applications in solid-state batteries.     

Pristine and Modified Porous Membranes for Zinc Slurry–Air Flow Battery

The membrane is a crucial component of Zn slurry–air flow battery since it provides ionic conductivity between the electrodes while avoiding the mixing of the two compartments. Herein, six commercial membranes (Cellophane™ 350PØØ, Zirfon^®, Fumatech^® PBI, Celgard^® 3501, 3401 and 5550) were first characterized in terms of electrolyte uptake, ion conductivity and zincate ion crossover, and tested in Zn slurry–air flow battery. The peak power density of the battery employing the membranes was found to depend on the in-situ cell resistance. Among them, the cell using Celgard^® 3501 membrane, with in-situ area resistance of 2 Ω cm² at room temperature displayed the highest peak power density (90 mW cm⁻²). However, due to the porous nature of most of these membranes, a significant crossover of zincate ions was observed. To address this issue, an ion-selective ionomer containing modified poly(phenylene oxide) (PPO) and N-spirocyclic quaternary ammonium monomer was coated on a Celgard^® 3501 membrane and crosslinked via UV irradiation (PPO-3.45 + 3501). Moreover, commercial FAA-3 solutions (FAA, Fumatech) were coated for comparison purpose. The successful impregnation of the membrane with the anion-exchange polymers was confirmed by SEM, FTIR and Hg porosimetry. The PPO-3.45 + 3501 membrane exhibited 18 times lower zincate ions crossover compared to that of the pristine membrane (5.2 × 10⁻¹³ vs. 9.2 × 10⁻¹² m² s⁻¹). With low zincate ions crossover and a peak power density of 66 mW cm⁻², the prepared membrane is a suitable candidate for rechargeable Zn slurry–air flow batteries.     

Glass–ceramic Li2S–P2S5 electrolytes prepared by a single step ball billing process and their application for all-solid-state lithium–ion batteries

We report that glass–ceramic Li₂S–P₂S₅ electrolytes can be prepared by a single step ball milling (SSBM) process. Mechanical ball milling of the xLi₂S·(100 − x)P₂S₅ system at 55 °C produced crystalline glass–ceramic materials exhibiting high Li-ion conductivity over 10⁻³ S cm⁻¹ at room temperature with a wide electrochemical stability window of 5 V. Silicon nanoparticles were evaluated as anode material in a solid-state Li battery employing the glass–ceramic electrolyte produced by the SSBM process and showed outstanding cycling stability.     

HTO/Cellulose Aerogel for Rapid and Highly Selective Li+ Recovery from Seawater

To achieve rapid and highly efficient recovery of Li⁺ from seawater, a series of H₂TiO₃/cellulose aerogels (HTO/CA) with a porous network were prepared by a simple and effective method. The as-prepared HTO/CA were characterized and their Li⁺ adsorption performance was evaluated. The obtained results revealed that the maximum capacity of HTO/CA to adsorb Li⁺ was 28.58 ± 0.71 mg g⁻¹. The dynamic k₂ value indicated that the Li⁺ adsorption rate of HTO/CA was nearly five times that of HTO powder. Furthermore, the aerogel retained extremely high Li⁺ selectivity compared with Mg²⁺, Ca²⁺, K⁺, and Na⁺. After regeneration for five cycles, the HTO/CA retained a Li⁺ adsorption capacity of 22.95 mg g⁻¹. Moreover, the HTO/CA showed an excellent adsorption efficiency of 69.93% ± 0.04% and high selectivity to Li⁺ in actual seawater. These findings confirm its potential as an adsorbent for recovering Li⁺ from seawater.