High Lithium Ion Conductivity Research Articles

Dual-type gel polymer electrolyte for high-voltage lithium metal batteries with excellent cycle life

The most attractive approach for maximizing the energy density of rechargeable lithium batteries is to combine a lithium metal anode with a high-voltage cathode. However, the dendritic formation of lithium at the anode and the highly oxidizing conditions that cause electrolyte decomposition at the cathode have hindered the practical development of lithium metal batteries (LMBs). In this study, we report a dual-type gel polymer electrolyte (GPE) composed of an anolyte and a catholyte that can address the drawbacks of both the anode and cathode sides. The anolyte is a poly(ethylene oxide)-based composite solid polymer electrolyte that is chemically stable with lithium metal and has a high mechanical strength for suppressing lithium dendrite growth. A cross-linked gel polymer electrolyte with high lithium-ion conductivity and oxidative stability was used as the catholyte. The Li/LiCoO2 cell assembled with a dual-type GPE exhibited a high discharge capacity of 181.1 mAh g−1 (areal capacity: 3.15 mAh cm−2) in the voltage range of 3.0–4.5 V and excellent cycle life, with a capacity retention of 74 % after 700 cycles at 25 °C and 0.5 C rate. Our study proposes a promising electrolyte system for LMBs with high energy density and good cycle life.

Atom substitution of the solid-state electrolyte Li10GeP2S12 for stabilized all-solid-state lithium metal batteries

Solid-state electrolyte Li10GeP2S12 (LGPS) has a high lithium ion conductivity of 12 mS cm−1 at room temperature, but its inferior chemical stability against lithium metal anode impedes its practical application. Among all solutions, Ge atom substitution of the solid-state electrolyte LGPS stands out as the most promising solution to this interface problem. A systematic screening framework for Ge atom substitution including ionic conductivity, thermodynamic stability, electronic and mechanical properties is utilized to solve it. For fast screening, an enhanced model DopNetFC using chemical formulas for the dataset is adopted to predict ionic conductivity. Finally, Li10SrP2S12 (LSrPS) is screened out, which has high lithium ion conductivity (12.58 mS cm−1). In addition, an enhanced migration of lithium ion across the LSrPS/Li interface is found. Meanwhile, compared to the LGPS/Li interface, LSrPS/Li interface exhibits a larger Schottky barrier (0.134 eV), smaller electron transfer region (3.103 Å), and enhanced ability to block additional electrons, all of which contribute to the stabilized interface. The applied theoretical atom substitution screening framework with the aid of machine learning can be extended to rapid determination of modified specific material schemes.

MoS2/WS2 quantum dots co-doped two-dimensional carbon nanosheets with high lithium ion conductivity

MoS2/WS2 quantum dots co-doped two-dimensional carbon nanosheets with high lithium ion conductivity

High Throughput Studies of Doped Li-La-Zr-O Garnet Solid Electrolytes

Lithium lanthanum zirconium oxide (LLZO) is a leading candidate for solid Li-batteries due to its high lithium-ion conductivity, stability in air and against Li metal, and compatibility with high-voltage cathodes.1,2 Despite significant research being done, our understanding of LLZO is limited by the relatively small number of compositions which have been studied; both in the larger Li-La-Zr-O system and in the doped cubic LLZO system, which can accommodate an extremely wide range of dopants.3To study this large number of compositions, we have applied a high-throughput methodology for synthesizing, characterizing, and testing sets of 64 LLZO electrolytes at the mg-scale. We employ a citrate sol-gel synthesis method whereby reagent solutions are dispensed across a well-plate to give a composition gradient. After drying and calcining the gels, the resulting powders are pelleted and then sintered at the desired temperature. High-throughput characterization techniques utilized include powder X-ray diffraction, impedance spectroscopy, DC polarization, and electrochemical stability window testing.Using our methodology, we have recently studied over 700 samples to produce a full phase stability diagram for the Li-La-Zr-O pseudoternary system.4 We found there is significant solubility of Li in the La2Zr2O7 pyrochlore structure, and that both cubic and tetragonal undoped LLZO appearing throughout the system have similarly poor bulk conductivities. This previous study again emphasizes the key role dopants play in LLZO. Herein, our methodology is applied to a comprehensive doping study where 60 different dopants are evaluated under identical synthesis conditions to allow for a thorough understanding of dopant effects on structure, ionic conductivity, electronic conductivity, and electrochemical stability window. Our samples achieve high conductivities over 1 mS/cm and relative densities above 90% with our combinatorial synthesis. Dopant content is optimized for each promising dopant to compare best-case results and correlate performance with structural properties like lattice parameters and density. Since comparing dopants in the literature is often difficult due to varying synthesis methods, this systematic work is essential in rational design of these electrolytes.1.Q. Liu, et al., J. Power Sources 2018, 389, 120-134.2.T. Thompson, et al., ACS Energy Letters 2017, 2, 462-468.3.F. Zheng, et al., J. Power Sources 2018, 389, 198-213.4.E. Anderson et al., DOI:10.1016/j.ssi.2022.116087.

High Performance Anode-Free Lithium Pouch Cells Employing Lithiophilic Gel Polymer Electrolyte with Ion Conductive Network

Anode-free lithium metal batteries have recently emerged as a next generation battery due to increased energy density by adopting bare current collector as an anode without excess lithium source. However, lithium tends to grow in uncontrolled dendritic form when depositied on a heterogeneous current collector, which eventually leads to low coloumbic efficiency and poor life span of the battery. Recent studies have attempted to apply artificial solid electrolyte interphase (SEI) on the current collector to solve theses problems. PEO-based polymeric artificial SEI is commonly used due to high lithium ion conductivity and flexiblility, but its weak physical properties limit its practical application. Herein, we report a chemically cross-linked poly (ethylene glycol) diacrylate (PEGDA)-based gel polymer electrolyte containing AgNO3 as Li nucleation seed for uniform Li deposition. It guides uniform Li-ion flux at the electrode/electrolyte interface and provides mechanical strength to suppress lithium dendrite growth. The gel polymer electrolyte was applied to anode free pouch cell and its cycling performance was investigated in the voltage range of 3.6 - 4.3 V at 0.5 C rate. Our results demonstrate that the proper combination of electrolyte and current collector can increase the conversion of polymerization and achieve stable interfacial properties with electrodes, resulting in improvement of the cycle life of anode free lithium pouch cell.

Combined Electrochemical, XPS, and STXM Study of Lithium Nitride as a Protective Coating for Lithium Metal and Lithium-Sulfur Batteries.

Li3N is an excellent protective coating material for lithium electrodes with very high lithium-ion conductivity and low electronic conductivity, but the formation of stable and homogeneous coatings is technically very difficult. Here, we show that protective Li3N coatings can be simply formed by the direct reaction of electrodeposited lithium electrodes with N2 gas, whereas using battery-grade lithium foil is problematic due to the presence of a native passivation layer that hampers that reaction. The protective Li3N coating is effective at preventing lithium dendrite formation, as found from unidirectional plating and plating-stripping measurements in Li-Li cells. The Li3N coating also efficiently suppresses the parasitic reactions of polysulfides and other electrolyte species with the lithium electrode, as demonstrated by scanning transmission X-ray microscopy, X-ray photoelectron spectroscopy, and optical microscopy. The protection of the lithium electrode against corrosion by polysulfides and other electrolyte species, as well as the promotion of smooth deposits without dendrites, makes the Li3N coating highly promising for applications in lithium metal batteries, such as lithium-sulfur batteries. The present findings show that the formation of Li3N can be achieved with lithium electrodes covered by a secondary electrolyte interface layer, which proves that the in situ formation of Li3N coatings inside the batteries is attainable.

Influence of Li3BO3 on the stability of Li1.5Al0.5Ge1.5(PO4)3 glass-ceramics with Li4Ti5O12 anode

All-solid-state Li+ batteries have a number of advantages over traditional batteries with a liquid electrolyte. One of the key problems related to their creation is the choice of compatible materials. In this work, the chemical and thermal stability of Li1.5Al0.5Ge1.5(PO4)3 solid electrolyte versus Li4Ti5O12 anode was studied. Nanostructured Li4Ti5O12 powder with the mean particle size of about 500 nm was synthesized by sol-gel method. NASICON-type structured Li1.5Al0.5Ge1.5(PO4)3 solid electrolyte obtained by the crystallization of the monolithic glass exhibits a high lithium-ion conductivity (5·10−4 S cm−1 at 25 °C) and a compact microstructure. The thermal behavior of their mechanical mixture and the resistance of the solid electrolyte|electrode half-cells were investigated. The influence of Li3BO3 addition on the interface between the solid electrolyte and composite anode is also discussed. According to DSC data, the interaction of Li1.5Al0.5Ge1.5(PO4)3 with Li4Ti5O12 begins at 545 °C, while Li3BO3 leads to a slight increase in their thermal stability up to 632 °C. It was established that Li2TiO3 and TiO2 impurities are formed after annealing the Li1.5Al0.5Ge1.5(PO4)3:Li4Ti5O12 mixture at 600 and 700 °C. However, Li3PO4 and AlPO4 phases begin to appear after annealing the studied mixture at 800 °C. In case of the Li3BO3-containing mixture, Li4B2O5, Li3PO4, LiTi2O4 and AlPO4 phases are formed only after annealing at 700 °C, while heating at 800 °C leads to the complete degradation of the Li1.5Al0.5Ge1.5(PO4)3 solid electrolyte. The resistance of the cells with Li4Ti5O12 anode decreases when the annealing temperature rises from 500 to 800 °C. The introduction of Li3BO3 into the composite anode leads to an increase in the interface resistance under the same heat treatment conditions.

Surface modification and chemical stability of garnet LLZO solid electrolyte by ZnO coating through a facile and practical method

All-solid-state lithium-ion batteries are promising choices to resolve high lithium-ion conductivity safety problems; however, they still have severe bottlenecks hindering their potential to be fully commercialized. This paper addresses interfacial resistance and a strong tendency to react with air and humidity. For this purpose, a Ga–Ta co-doped Li7La3Zr2O12 (LLZO) is dip-coated in an alcoholic zinc acetate solution to produce a thin zinc oxide (ZnO) layer after calcination to investigate any possible effects on reducing the interfacial resistance between electrolyte and anode. Furthermore, the effect of the ZnO layer on lithium deterioration (producing Li2CO3 or LiOH during air exposure) is examined by Fourier-transform Infrared spectroscopy (FTIR), Raman spectroscopy, field emission scanning electron microscopy (FESEM) and electrochemical impedance spectroscopy (EIS) after exposing both coated and uncoated LLZO to relatively humidified air for 30 days. Results indicate that LLZO electrolyte coated with ZnO in the thickness range of 400–600 nm obtained the highest ionic conductivity, i.e. 41% and 52% increase for Au/LLZO/Au and Li/LLZO/Li cells, respectively, compared to the pristine sample. After 30 days of exposure to humidified air, the coated electrolyte shows way better electrochemical results (0.62 mS/cm rather than 0.01 mS/cm for the uncoated sample) and a lower amount of Li2CO3 than the uncoated one.

Polysulfide Rejection Strategy in Lithium-Sulfur Batteries Using an Ion-Conducting Gel-Polymer Interlayer Membrane.

Lithium-sulfur batteries (LiSBs) are emerging as promising alternative to conventional secondary lithium-ion batteries (LiBs) due to their high energy density, low cost, and environmental friendliness. However, preventing polysulfide dissolution is a great challenge for their commercial viability. The present work is focused on preparing a lithium salt and ionic liquid (IL) solution (SIL) impregnated ion (lithium ion)-conducting gel-polymer membrane (IC-GPM) interlayer to prevent polysulfide migration toward the anode by using an electrostatic rejection and trapping strategy. Herein, we introduce an SIL-based freestanding optimized IC-GPM70 (70 wt % SIL) interlayer membrane with high lithium-ion conductivity (2.58 × 10-3 S cm-1) along with excellent thermal stability to suppress the migration of polysulfide toward the anode and prevent polysulfide dissolution in the electrolyte. Because of the coulombic interaction, the anionic groups, -CF2 of the β-phase polymer host PVdF-HFP, TFSI- anion of IL EMIMTFSI, and anion BOB- of LIBOB salt, allow hopping of positively charged lithium ions (Li+) but reject negatively charged and relatively large-sized polysulfide anions (Sx-2, 4 <x <8). The cationic group EMIM+ of the IL is electrostatically able to attract and trap the polysulfides in the interlayer membrane. Since the shuttle effect of lithium polysulfides in LiSBs has been suppressed by the prepared IC-GPM70 interlayer, the resulting lithium-sulfur cell exhibits significantly higher cycling stability (1200 cycles), rate performance (1343, 1208, 1043, 875, and 662 mAh g-1 at 0.1C, 0.2C, 0.5C, 1C, and 2C, respectively), and structural integrity during cycling than its counterpart without the IC-GPM70 interlayer. The interlayer membrane has been found to improve the performance and durability of LiSBs, thus making them a viable alternative to conventional LiBs.

A solid-state electrolyte incorporating Li6.25Al0.25La3Zr2O12 into an ethylene oxide-based network for use in lithium metal batteries

In this study, solid-state hybrid electrolytes (ENLSEs) appropriate for use in a lithium metal battery (LMB) are produced with an ethylene oxide-basis network and garnet Li7La3Zr2O12 (LLZO) via solvent-free UV polymerization. The optimum composition of ENLSE is determined by varying the weight ratio of the ethylene oxide network, LLZO, and lithium salt. The ENLSEs show high lithium-ion conductivity (1.03 × 10−4 S cm−1) at 50 °C, a result of the concurrent Li+ transport of ethylene-oxide chain and LLZO. The electrolytes exhibit a high voltage stability of 5.75 V (vs Li/Li+) and a considerable lithium-ion transfer number (tLi+∼0.68), suppress dendrite growth, and promote electrochemical stability. A LMB full cell delivers 99.4 mA h g−1 of capacity at a current of 5 mA g−1 with 55 % capacity retention over at least 70 charge-discharge cycles, suggesting that ENLSEs have potential as solid-state electrolytes for LMBs.

Spectroscopic Investigation of Li3PS4-LiI Sulfide-Based Glass-Ceramic Solid Electrolytes after Moisture Exposure

Sulfide-based solid electrolytes (SEs) have been extensively studied because of their high lithium-ion conductivities. Among the solid electrolytes, glass or glass-ceramic SEs have suitable thermoplastic characteristics for battery manufacturing processes. However, sulfide-based SEs react strongly with moisture, resulting in toxic H2S gas generation and reduced lithium-ion conductivity. Although the effects of moisture exposure on sulfide-based SEs have been investigated by some researchers, related studies are scarce and further research is required. In this study, X-ray photoelectron spectroscopy (XPS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were performed to investigate the structural changes in a glass-ceramic sulfide-based SE, viz., Li3PS4-0.2LiI before and after exposure to moisture, focusing on the changes in the surface chemical species, adsorbed H2O, and related species. In addition, SE samples exposed to moist air were subjected to recovery treatment by vacuum heating. XPS and DRIFTS analyses revealed that the main reason for the decrease in the lithium-ion conductivity of the glass-ceramic SE after moisture exposure is the adsorption of water onto the SE surface and/or its hydration. In particular, the H2O layer adsorbed to the SE surface physically and/or chemically decreases the lithium-ion conductivity at the grain boundaries (i.e., SE/SE interface), although the bulk conduction is maintained.

Improved Route to Linear Triblock Copolymers by Coupling with Glycidyl Ether-Activated Poly(ethylene oxide) Chains.

Poly(ethylene oxide) block copolymers (PEOz BCP) have been demonstrated to exhibit remarkably high lithium ion (Li+) conductivity for Li+ batteries applications. For linear poly(isoprene)-b-poly(styrene)-b-poly(ethylene oxide) triblock copolymers (PIxPSyPEOz), a pronounced maximum ion conductivity was reported for short PEOz molecular weights around 2 kg mol-1. To later enable a systematic exploration of the influence of the PIx and PSy block lengths and related morphologies on the ion conductivity, a synthetic method is needed where the short PEOz block length can be kept constant, while the PIx and PSy block lengths could be systematically and independently varied. Here, we introduce a glycidyl ether route that allows covalent attachment of pre-synthesized glycidyl-end functionalized PEOz chains to terminate PIxPSy BCPs. The attachment proceeds to full conversion in a simplified and reproducible one-pot polymerization such that PIxPSyPEOz with narrow chain length distribution and a fixed PEOz block length of z = 1.9 kg mol-1 and a Đ = 1.03 are obtained. The successful quantitative end group modification of the PEOz block was verified by nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). We demonstrate further that with a controlled casting process, ordered microphases with macroscopic long-range directional order can be fabricated, as demonstrated by small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It has already been shown in a patent, published by us, that BCPs from the synthesis method presented here exhibit comparable or even higher ionic conductivities than those previously published. Therefore, this PEOz BCP system is ideally suitable to relate BCP morphology, order and orientation to macroscopic Li+ conductivity in Li+ batteries.

Lattice Structures, Electronic Properties and Lithium-ion Transport Dynamics of Li10SnP2S12/Li interface

All-solid-state lithium-sulfur batteries (ASSLSBs) are considered one of the most desirable battery technologies thanks to their ultra-high theoretical capacity, low cost, and environmental friendliness. Li10GeP2S12 (LGPS), the existing solid electrolyte with the highest lithium-ion conductivity, is supposed to be replaced by Li10SnP2S12 (LSPS). Current LSPS-related applications and researches focus on structural properties, electrochemical performance, and interface regulation, while such topics as surface properties, interface properties, and the lithium-ion transport mechanism of LSPS interface with metal Li anode are rarely mentioned. Therefore, this paper investigates the interfacial structure, electrical properties, and lithium-ion transport of the LSPS/Li interface using the first-principles calculation method, observing the formation of a interface layer between LSPS and Li, which blocks the conduction of electrons, accelerates the diffusion of lithium-ion, and undermines their surface structures. Ab initio molecular dynamics (AIMD) simulations confirm that the interface benefits Li+ conduction. In addition, S and P in the surface layer of LSPS experience rapid diffusion and eventually penetrate deep into the metal Li anode to dent its integrity, which indicates less active material, disrupted anode surface structure, worse battery performance, and safety issues. This paper may theoretically guide the future application of LSPS in practical engineering.

ПЕРСПЕКТИВНЫЕ НЕОРГАНИЧЕСКИЕ ТВЕРДЫЕ ЭЛЕКТРОЛИТЫ С ЛИТИЙ-ИОННОЙ ПРОВОДИМОСТЬЮ

New effective methods for the synthesis of inorganic solid electrolytes with high lithium-ion conductivity at room temperature have been developed at ICTREMRM KSC RAS. These are solid electrolytes of the composition Li1+xAlxTi2-x(PO4)3 (LATP) and Li1+xAlxGe2-x(PO4)3 (LAGP) with a NASICON structure and with a garnet structure of the composition Li7-3хAlxLa3Zr2O12 (LLZ) with a wide window of electrochemical stability. Synthesis methods are easily scaled, do not require complex technological equipment and are protected by patents of the RF. The report presents the results of physico-chemical, thermal and electrochemical studies of synthesized materials by modern methods. Morphology and microstructure were studied by scanning electron microscopy. The values of the specific ionic conductivity for LATP, LAGP and LLZ at room temperature, measured by impedance spectroscopy, were in the range of 10-3–10-4 S/cm, which corresponds to the maximum values for solid electrolytes of the specified composition. The temperature dependence of the ionic conductivity in the range of 25-200°C was studied and the activation energy of the conductivity (0.28–0.42 eV). Based on electrochemical characteristics, synthesized solid electrolytes are promising materials for all solid-state lithium-ion batteries.

Single-Ion Gel Polymer Electrolyte based on In-Situ UV Irradiation Cross-Linked Polyimide Complexed with PEO for Lithium-Ion Batteries.

Lithium-ion batteries (LIBs) have become the research focus of energy storage products. Due to the combination of Li+ and the Lewis basic sites of polymer chains, anions move more than five times faster, which do not participate in the electrode reaction during the discharge cycles, leading to concentration polarization, voltage losses, and high internal resistance. To solve this phenomenon, in this work, a polymer network structure of single-ion polymer electrolyte-based polyimide (DPI-SIGPE) with plasticizer ethylene carbonate (EC)/dimethyl carbonate (DMC) is formed by in-situ cross-linking double bond polyimide, 4-styrene sulfonyl (benzenesulfonyl) imide, and cross-linking agent pentaerythritol tetra(2-thiol acetate) under UV irradiation. By incorporating the anion as a part of the polymer chain, DPI-SIGPE exhibits high lithium-ion conductivity of 2.7 × 10-4 S cm-1 at 30 °C and transference number of 0.87. Typical lithium stripping/plating cycling of 900h demonstrates uniform lithium deposition impacted by DPI-SIGPE. Meanwhile, it has good dimensional thermal stability with no obvious shrinkage at 200 °C for 0.5h and wide electrochemical window of 4.6V. Thus, the polyimide-based cross-linked single-ion gel polymer electrolyte has the promising potential for application in LIBs.

Low-Temperature Sintering of a Garnet-Type Li6.5La3Zr1.5Ta0.5O12 Solid Electrolyte and an All-Solid-State Lithium-Ion Battery.

Garnet-type Ta-substituted Li7La3Zr2O12 materials attract considerable attention as solid electrolytes for use in future oxide-based all-solid-state lithium-ion batteries owing to their superior ionic conductivity and chemical and electrochemical stabilities. However, high-temperature sintering above 1000 °C, which is needed to realize high lithium-ion conductivity, results in the formation of insulating interface impurities at the electrode-electrolyte interface. Herein, the low-temperature sintering of the Li6.5La3Zr1.5Ta0.5O12 (LLZT) solid electrolyte at a remarkably low temperature of 400 °C was demonstrated using the submicrometer-sized garnet-type LLZT fine powder sample prepared at 600 °C through a reaction of Li2O and La2.4Zr1.2Ta0.4O7. The lithium-ion conductivity at 25 °C was 4.54 × 10-5 S cm-1 without any additives through low-temperature sintering at 400 °C. In addition, the preliminary battery performance of the oxide-based all-solid-state LiNi1/3Co1/3Mn1/3O2-Li4Ti5O12 full-battery cell fabricated at 400 °C using the present LLZT fine powder sample as the solid electrolyte was demonstrated.

High Lithium-Ion Conductivity, Halide-Coated, Ni-Rich NCM Improves Cycling Stability in Sulfide All-Solid-State Batteries

All-solid-state batteries attract significant attention owing to their potential to realize an energy storage system with higher safety and energy density. In this work, a halide electrolyte coating with high lithium-ion conductivity obtained by mechanical coating under n-heptane solvent and annealing at 200 °C of Ni-rich LiNi0.83Co0.14Mn0.03O2 (NCM) for Li6PS5Cl-type all-solid-state batteries is reported. A 10% Li3InCl6-coated NCM material was assembled into a 10% LIC@NCM/Li6PS5Cl/In all-solid-state battery with an initial charge capacity of 201.3 mAh g–1, a discharge specific capacity of 158.7 mAh g–1, and a Coulombic efficiency of 79.06%. After 100 cycles at room temperature at 0.1C current density, the capacity retention was 92% and the capacity retention was 72% after 270 cycles. In comparison, all-solid-state batteries using matched Li6PS5Cl and untreated NCM had a capacity retention rate of 53% after 100 cycles at 0.1C under the same charge/discharge regime and environment. It is indicated that the cycling performance and rate performance of the NCM material significantly improve after the 10% LIC coating. In this paper, X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), high-resolution high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), and other tests and analyses confirmed the following: the pregenerated interfacial layer of approximately 2 nm on the surface of NCM after the 10% halide solid electrolyte coating improves the structural stability of the material during charging and discharging, the LIC coating layer slows down the decomposition of LI6PS5Cl during cycling, and the capacity increase at high rates is due to the reduction of the interfacial impedance between the cathode material and LI6PS5Cl solid electrolyte.

A dielectric electrolyte composite with high lithium-ion conductivity for high-voltage solid-state lithium metal batteries.

The ionic conductivity of composite solid-state electrolytes does not meet the application requirements of solid-state lithium (Li) metal batteries owing to the harsh space charge layer of different phases and low concentration of movable Li+. Herein, we propose a robust strategy for creating high-throughput Li+ transport pathways by coupling the ceramic dielectric and electrolyte to overcome the low ionic conductivity challenge of composite solid-state electrolytes. A highly conductive and dielectric composite solid-state electrolyte is constructed by compositing the poly(vinylidene difluoride) matrix and the BaTiO3-Li0.33La0.56TiO3-x nanowires with a side-by-side heterojunction structure (PVBL). The polarized dielectric BaTiO3 greatly promotes the dissociation of Li salt to produce more movable Li+, which locally and spontaneously transfers across the interface to coupled Li0.33La0.56TiO3-x for highly efficient transport. The BaTiO3-Li0.33La0.56TiO3-x effectively restrains the formation of the space charge layer with poly(vinylidene difluoride). These coupling effects contribute to a quite high ionic conductivity (8.2 × 10-4 S cm-1) and lithium transference number (0.57) of the PVBL at 25 °C. The PVBL also homogenizes the interfacial electric field with electrodes. The LiNi0.8Co0.1Mn0.1O2/PVBL/Li solid-state batteries stably cycle 1,500 times at a current density of 180 mA g-1, and pouch batteries also exhibit an excellent electrochemical and safety performance.

A single-ion conducting quasi-solid polymer electrolyte made from synthetic rubber for lithium metal batteries

A lithium-ion conducting triblock copolymer bearing pendant lithium sulfonates, termed as SSEBS-Li, is derived from commercial synthetic rubber poly(styrene-block-(ethylene-ran-butylene)-block-styrene); and free-standing quasi-solid polymer electrolyte (QSPE) membranes made of demonstrate high efficiency and high safety in the application for lithium metal batteries (LMBs). SSEBS-Li possesses a hybrid molecular structure containing “soft” segments that enable seamless contact with the lithium metal; and “hard” segments possessing anchored anions that offer continuous pathways to benefit lithium ion conduction and homogeneous lithium deposition. The unique molecular architecture features the QSPE membranes interpenetrated network microstructures to provide good mechanical strengths and ductility at a thickness of 25 µm. A high lithium ion conductivity of up to 5 × 10-4 S cm−1 at ∼ 35 wt% liquid electrolyte uptake is achieved, along with a high lithium transference number of 0.92 at room temperature. Galvanostatic cycling studies prove the excellent capability of SSEBS-Li QSPE in suppressing lithium dendrite growth. The Li//QSPE//LFP cell exhibits a high discharge capacity and excellent long-term stability after 300 cycles at 0.5C and room temperature without deleterious decay, elucidating a feasible and economical approach to improve the stability and safety of LMBs.

New Oxyhalide Solid Electrolytes with High Lithium Ionic Conductivity >10 mS cm-1 for All-Solid-State Batteries.

All-solid-state batteries (ASSBs) with inorganic solid electrolytes (SEs) have attracted significant interest as next-generation energy storage. Halides such as Li3 YCl6 are promising candidates for SE because they combine high oxidation stability and deformability. However, the ionic conductivities of halide SEs are not as high as those of other SEs, especially sulfides. Here, we discover new lithium-metal-oxy-halide materials, LiMOCl4 (M=Nb, Ta). They exhibit extremely high ionic conductivities of 10.4 mS cm-1 for M=Nb and 12.4 mS cm-1 for M=Ta, respectively, even in cold-pressed powder forms at room temperature, which are comparable to or surpass those of organic liquid electrolytes used in lithium-ion batteries. Bulk-type ASSB cells using the oxyhalides as the cathode SE demonstrate an outstanding rate capability with a capacity retention of 80 % at 5 C/0.1 C. We believe that the proposed oxyhalides are promising SE candidates for the practical applications of ASSBs.