High Conductivity Solid Electrolyte Research Articles

High ionic conductive Sodium β-alumina (SBA) and SBA-NaPF6 composite solid electrolytes prepared by cold sintering process

Sodium β-alumina (SBA) electrolytes are among the most excellent candidates for all-solid-state batteries due to their high electrochemical performances and low cost of sodium resources. However, thermally sintering at above 1400 °C is required to fabricate high dense SBA electrolytes, thus giving rise to a huge energy consumption. Here, dense SBA electrolytes and (1-x)SBA-xNaPF6 (x=5, 10, 15, 20 wt%) composites were fabricated using cold sintering process (CSP) below 300 °C with 2 mol/L NaOH solution as transient chemistry. The ionic conductivity of SBA electrolytes is significantly enhanced from 5.53×10-6 S·cm-1 to 5.91 × 10−4 S·cm−1 as 15 wt% NaPF6 was introduced to the composite, which is comparable with the SBA sintered above 1400 °C. CSP may provide a promising approach for the fabrication of solid-state electrolytes by avoiding the detrimental impact of high temperature heat treatment.

Curved surface coupled structural battery composites manufactured by resin transfer molding process: Microstructure and multifunctional performance

To bridge industrial production and lab-scale research, this work demonstrates a technology to manufacture curved surface structural battery composites (CSBCs) that can simultaneously achieve electrochemical energy storage and load-bearing. The curved-surface carbon fiber structural anode and cathode are fabricated by coating the active materials on carbon fiber fabric with a vacuum-bag-assisted technique. The resin transfer molding (RTM) process is conducted to manufacture the coupled CSBCs by infusing bi-continuous phase epoxy resin electrolyte and curing at high temperatures. The microstructure of structural electrodes and CSBCs is characterized by scanning electron microscopy (SEM). Due to good interfacial compatibility between high mechanical strength carbon fiber structural electrode and high ionic conductivity solid polymer electrolyte bulk for load support, the fabricated CSBCs demonstrate a high density of 294 mWh kg−1 based on the whole mass of devices, a tensile strength of 257.4 MPa with Young's modulus of 12.9 GPa and a flexural strength of 194.1 MPa with flexural modulus of 11.1 GPa. In situ electrochemical-mechanical tests further confirm the durability of CSBCs under mechanical loads with a multifunctional efficiency of 1.07, suggesting the effectiveness of the introduced manufacturing techniques for coupled structural battery composites.

Tungsten and Boron Codoping toward High Ionic Conductivity and Stable Sodium Solid Electrolyte for All-Solid-State Sodium Batteries.

Sodium solid electrolytes with high ionic conductivity and good interfacial stability with sodium metal are crucial to realize high-performance all-solid-state sodium batteries. In this work, W and B-codoped Na3Sb1-xWxS4-xBx solid electrolytes are prepared by melt-quenching with further annealing. The synthesized Na3Sb0.95W0.05S3.95B0.05 solid electrolyte possesses a high ionic conductivity of 11.06 mS cm-1 under 25 °C and shows significantly improved interface compatibility with metal sodium. Specifically, Na/Na3Sb0.95W0.05S3.95B0.05/Na symmetric cell can stable cycle for 500 h under a current density of 0.05 mA cm-2. In addition, the resultant TiS2/Na3Sb0.95W0.05S3.95B0.05/Na battery exhibits an initial charge capacity of 164.1 mAh g-1 at 0.1 C with a capacity retention of 76.4% after 100 cycles. This work provides a new strategy to realize the high ionic conductivity of sodium solid electrolytes with improved interfacial stability with sodium anode.

First-principles study on a new chloride solid lithium-ion conductor material with high ionic conductivity

Through the replacement-screening strategy, a high ionic conductivity solid electrolyte material LiSbCl6 was discovered, and its transport mechanism was investigated in comparison with NaSbCl6 by first-principles calculations.

Sodium Penetration in Nasicon Solid Electrolytes Under High Current

High conductivity solid electrolytes, such as NaSICON, are poised to play an increasingly important role in safe, reliable battery-based energy storage, enabling a new class of sodium-based batteries. Coupled demands of high current densities (≥0.1 A cm-2) and low temperature (<200 °C) operation, combined with increased discharge times for long duration storage (>12 h), challenge the limitations of solid electrolytes. Here, we explore the penetration of sodium into NaSICON at 0.1 A cm-2 in a symmetric molten sodium cell. Previous studies of β’’-alumina proposed that Poiseuille pressure-driven cracking (Mode I) and low levels of electronic conductivity leading to ion-electron recombination (Mode II) can cause metal accumulation within solid electrolytes, but a comprehensive study at high current density is necessary. To understand and differentiate these modes in NaSICON, this work employs unidirectional galvanostatic testing of Na|NaSICON|Na symmetric cells at 0.1 A cm-2 over 23 1-hour intervals at 110 °C. While galvanostatic testing shows a relatively constant, yet increasingly noisy voltage profile, electrochemical impedance spectroscopy (EIS) between intervals reveals a significant decrease in cell impedance which can be correlated with sodium metal penetration, as observed in scanning electron microscopy (SEM). Significant sodium accumulation from the stripping-side electrode suggests that Mode II failure may be far more prevalent than previously considered. Further, these findings suggest that total charge transported per unit area (mAh cm-2), an important parameter for long duration storage, may be a more critical parameter than current density (mA cm-2) when examining solid electrolyte failure. Together, these results provide a better understanding of the limitations of NaSICON solid electrolytes under high current density and can guide the design of coatings to improve electrode-electrolyte interfaces.

Molten Sodium Penetration Through Solid-State Nasicon Electrolytes Under High Current

High conductivity solid electrolytes, such as NaSICON, are poised to play an increasingly important role in safe, reliable battery-based energy storage, enabling a new class of sodium-based batteries. Increasing demands of both high current densities (≥0.1 A cm-2) and low temperature (<200 °C) operation, coupled with increased discharge times for long duration storage (>12 h), challenge the limitations of solid electrolytes. Here, we explore the penetration of sodium into NaSICON at 0.1 A cm-2 in a symmetric molten sodium cell. Previous studies of β’’-alumina proposed that Poiseuille pressure-driven cracking (Mode I) and low levels of electronic conductivity leading to ion-electron recombination (Mode II) can cause metal accumulation within solid electrolytes, but a comprehensive study at high current density is necessary. To understand and differentiate these modes in NaSICON, this work employs unidirectional galvanostatic testing of Na|NaSICON|Na symmetric cells at 0.1 A cm-2 over 23 1-hour intervals at 110 °C. While galvanostatic testing shows a relatively constant, yet increasingly noisy voltage profile, electrochemical impedance spectroscopy (EIS) between intervals reveals a significant decrease in cell impedance which can be correlated with sodium metal penetration, as observed in scanning electron microscopy (SEM). Significant sodium accumulation from the stripping-side electrode suggests that Mode II failure may be far more prevalent than previously considered. Further, these findings suggest that total charge transported per unit area (mAh cm-2), an important parameter for long duration storage, may be a more critical parameter than current density (mA cm-2) when examining solid electrolyte failure. Together, these results provide a better understanding of the limitations of NaSICON solid electrolytes under high current density and can guide the design of coatings to improve electrode-electrolyte interfaces.

The Relationship between Ionic Conductivity and Solvation Structures of Localized High-Concentration Fluorinated Electrolytes for Lithium-Ion Batteries.

Localized high-concentration electrolytes (LHCEs) combine a diluent with a high-concentration electrolyte, offering promising properties. The ions, solvent, and diluent interact to form complex heterogeneous liquid structures, where high salt concentration clusters are embedded in the diluent. Optimizing LHCEs for desired electrolyte properties like high ionic conductivity, low viscosity, and effective solid electrolyte interphase (SEI) formation ability within the vast chemical and compositional design space requires deeper understanding and theoretical guidance. We investigated the structures and conductivities of LHCEs based on a fluorinated solvent with two different diluents at varying concentrations. 2,2,3,3-Tetrafluoropropyl trifluoroacetate (TFPTFA) enters the solvation cluster due to its stronger Li-ion interactions, whereas 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether (TFETFE) enters only at extremely high diluent concentrations. The ionic conductivity increases with decreasing diluent concentrations, with a slope change during cluster percolation. Overall, TFETFE demonstrates higher effectiveness than TFPTFA, forming higher local salt concentration clusters and resulting in higher ionic conductivity.

Molten Sodium Penetration in NaSICON Electrolytes at 0.1 A cm–2

High-conductivity solid electrolytes, such as the Na superionic conductor, NaSICON, are poised to play an increasingly important role in safe, reliable battery-based energy storage, enabling advanced sodium-based batteries. Coupled demands of increased current density (≥0.1 A cm–2) and low-temperature (<200 °C) operation, combined with increased discharge times for long-duration storage (>12 h), challenge the limitations of solid electrolytes. Here, we explore the penetration of molten sodium into NaSICON at high current densities. Previous studies of β″-alumina proposed that Poiseuille pressure-driven cracking (mode I) and recombination of ions and electrons within the solid electrolyte (mode II) are the two main mechanisms for Na penetration, but a comprehensive study of Na penetration in NaSICON is necessary, particularly at high current density. To further understand these modes, this work employs unidirectional galvanostatic testing of Na|NaSICON|Na symmetric cells at 0.1 A cm–2 over 23 h at 110 °C. While galvanostatic testing shows a relatively constant yet increasingly noisy voltage profile, electrochemical impedance spectroscopy (EIS) reveals a significant decrease in cell impedance correlated with significant sodium penetration, as observed in scanning electron microscopy (SEM). Further SEM analysis of sodium accumulation within NaSICON suggests that mode II failure may be far more prevalent than previously considered. Further, these findings suggest that total (dis)charge density (mAh cm–2), as opposed to current density (mA cm–2), may be a more critical parameter when examining solid electrolyte failure, highlighting the challenge of achieving long discharge times in batteries using solid electrolytes. Together, these results provide a better understanding of the limitations of NaSICON solid electrolytes under high current and emphasize the need for improved electrode–electrolyte interfaces.

Passerini polymerization as a novel route for high ionic conductivity solid polymer electrolyte

Polyethylene glycol (PEG) used as solid polymer electrolyte has shown disadvantages of low ionic conductivity and lithium ion transference number due to its high crystallinity. In this study, we propose Passerini three-component polymerization (P-3CP) to modify PEGs for solid polymer electrolytes (SPEs). Thus, a series of PEG-based polyesters (PGPEs) with molar masses between 14,400 and 30,200 gmol−1 are synthesized by P-3CP. The crystallinity of obtained PGPEs is successfully suppressed by the introduction of side groups via P-3CP. SPEs consisting of PGPEs as matrix and bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) with different concentrations were investigated in detail. The SPE composed of PGPE-4000 with 30 wt% LiTFSI presented the best ionic conductivities of 5.85 × 10-5 Scm−1 and 1.94 × 10-3 Scm−1 at room temperature and 80 °C, respectively, which are significantly higher than the commonly used PEG-based SPE. The LiFePO4/Li solid-state lithium-ion battery assembled with PGPE-based SPE showed excellent cycle stability. After 100 cycles at 0.5C at 60 °C, the discharge specific capacity remains 133 mAhg−1. Furthermore, due to the addition of amide side groups, the flame retardant property of PGPE-based SPEs is improved. Compared to PEG, the limiting oxygen index (LOI) values increase from 21.0 to 25.5 after modification by P-3CP. Therefore, the P-3CP is an attractive method to obtain polyesters from dicarboxylic acid or diol monomers for the application in the lithium battery field.

All-Solid-State Lithium Metal Batteries Enabled By Solid Electrolytes with Low-Temperature Processability

All-Solid-State lithium metal batteries are highly sought-after to improve the safety of high energy density batteries for electric vehicles, aircraft, and seacraft. Despite the proliferation of high-conductivity solid electrolytes, it remains a significant challenge to create conformal interfaces between them and the active materials in the battery. Furthermore, the poor electrochemical stability of known solid electrolytes often necessitates the co-design of protective coatings and interlayers, which increase cell resistance. Here, I will discuss a novel materials platform for advanced solid electrolytes that are readily processed at <150C, creating molecularly coherent interfaces with both lithium metal as well as a diverse selection of high-voltage storage materials and conductive carbons integrated in the cathode. I will describe how the composition may be tailored to achieve conductivity up to 10 mS/cm at ambient temperature. In stride, I will present electroanalytical and surface analytical characterization to define pathways for promoting or inhibiting the formation of interphases at the anode and cathode. Through control over interphases, we realize highly stable all-solid-state cells with >500 cycles with less than 80% capacity fade at current densities up to 1 mA/cm2 at an cell temperatures <45 C and stack pressures less than 0.5 MPa.

Na-doping approach for conductivity enhancement of natural phosphate derived fluorapatites

The search for thermally stable solid electrolytes is promising for solid-state batteries. High ionic conductivity solid electrolytes derived from natural phosphate modified by sodium addition were developed. The samples were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, 23Na solid-state nuclear magnetic resonance and scanning electron microscopy with energy dispersive spectroscopy. The structural and morphology changes were observed by increasing the Na2SO4 content. The synthesized ceramic electrolytes have low activation energy of about 0.60 eV and a relatively high ionic conductivity of 2 × 10−2 mS cm−1 at 400 °C.

Rate-Determining Process at Electrode/Electrolyte Interfaces for All-Solid-State Fluoride-Ion Batteries.

Developing high-performance solid electrolytes that are operable at room temperature is one of the toughest challenges related to all-solid-state fluoride-ion batteries (FIBs). In this study, tetragonal β-Pb0.78Sn1.22F4, a promising solid electrolyte material for mild-temperature applications, was modified through annealing under various atmospheres using thin-film models. The annealed samples exhibited preferential growth and enhanced ionic conductivities. The rate-determining factor for electrode/electrolyte interface reactions in all-solid-state FIBs was also investigated by comparing β-Pb0.78Sn1.22F4 with representative fluoride-ion- and lithium-ion-conductive materials, namely, LaF3, CeF3, and Li7La3Zr2O12. The overall rate constant of the interfacial reaction, k0, which included both mass and charge transfers, was determined using chronoamperometric measurements and Allen-Hickling simulations. Arrhenius-type correlations between k0 and temperature indicated that activation energies calculated from k0 and ionic conductivities (σion) were highly consistent. The results indicated that the mass transfer (electrolyte-side fluoride-ion conduction) should be the rate-determining process at the electrode/electrolyte interface. β-Pb0.78Sn1.22F4, with a large σion value, had a larger k0 value than Li7La3Zr2O12. Therefore, it is hoped that the development of high-conductivity solid electrolytes can lead to all-solid-state FIBs with superior rate capabilities similar to those of all-solid-state Li-ion batteries.

Black-Box Optimization for Automated Discovery.

In chemistry and materials science, researchers and engineers discover, design, and optimize chemical compounds or materials with their professional knowledge and techniques. At the highest level of abstraction, this process is formulated as black-box optimization. For instance, the trial-and-error process of synthesizing various molecules for better material properties can be regarded as optimizing a black-box function describing the relation between a chemical formula and its properties. Various black-box optimization algorithms have been developed in the machine learning and statistics communities. Recently, a number of researchers have reported successful applications of such algorithms to chemistry. They include the design of photofunctional molecules and medical drugs, optimization of thermal emission materials and high Li-ion conductive solid electrolytes, and discovery of a new phase in inorganic thin films for solar cells.There are a wide variety of algorithms available for black-box optimization, such as Bayesian optimization, reinforcement learning, and active learning. Practitioners need to select an appropriate algorithm or, in some cases, develop novel algorithms to meet their demands. It is also necessary to determine how to best combine machine learning techniques with quantum mechanics- and molecular mechanics-based simulations, and experiments. In this Account, we give an overview of recent studies regarding automated discovery, design, and optimization based on black-box optimization. The Account covers the following algorithms: Bayesian optimization to optimize the chemical or physical properties, an optimization method using a quantum annealer, best-arm identification, gray-box optimization, and reinforcement learning. In addition, we introduce active learning and boundless objective-free exploration, which may not fall into the category of black-box optimization.Data quality and quantity are key for the success of these automated discovery techniques. As laboratory automation and robotics are put forward, automated discovery algorithms would be able to match human performance at least in some domains in the near future.

Controllable magnetic field aligned sepiolite nanowires for high ionic conductivity and high safety PEO solid polymer electrolytes

Poly (ethylene oxide) (PEO) polymer electrolyte, attracts great attention owing to its excellent flexibility, good processability and high safety compared with liquid electrolytes. However, its low ionic conductivity and weak ability to suppress the lithium dendrite severely restrict the further progress of PEO. Herein, we prepare a high ionic conductivity solid polymer electrolyte for all-solid-state lithium batteries by mixing PEO and magnetically aligned functionalized sepiolite (KFSEP) nanowires. The ionic conductivity of PEO/LiTFSI/10%⊥KFSEP solid polymer electrolyte is 2.0 × 10−5 S cm−1 at 20 °C (The ionic conductivity of PEO/LiTFSI solid polymer electrolyte is 4.0 × 10−7 S cm−1 at 20 °C). The experiments and simulation analysis indicate that the aligned nanowires provide a fast-moving channel for lithium ions. The capacity of Li/PEO/LiTFSI/10%⊥KFSEP/LFP cell is 130 mAh g−1 at 1.0 C under 60 °C after 450cycles. Furthermore, Li/PEO/LiTFSI/10%⊥KFSEP/LFP cell shows 150 mAh g−1 at 0.2 C under 25 °C. The Li/PEO/LiTFSI/10%⊥KFSEP/Li cell can work normally more than 600 h, indicating the high stability and lithium dendrite suppressing function of PEO/LiTFSI/10%⊥KFSEP. Overall, a high performance solid polymer electrolyte with higher safety is constructed by incorporating magnetically aligned sepiolite nanowires into PEO.

A Na-rich fluorinated sulfate anti-perovskite with dual doping as solid electrolyte for Na metal solid state batteries

High-conductivity solid electrolytes are crucial components for the development of Na-based solid state batteries. However the electrolyte structure prototype and corresponding synthesis method are still lacking. The conventional oxide and sulfide electrolytes are precursor-expensive (e.g. Na2S) or energy-intensive in sintering synthesis (e.g. at 1000 ​°C). Here, we propose a novel anti-perovskite solid electrolyte of Na-rich fluorinated sulfate (Na3SO4F) benefiting from Mg and Cl co-doping by solid state reaction from low-cost precursors at moderate temperature (500 ​°C). The tailored dual doping enables an improvement of ionic conductivity by three orders of magnitude close to 10−4 ​S ​cm−1 at 60 ​°C. The creation of Na vacancies (by aliovalent Mg doping) and lattice expansion (by substituting F sites with larger-sized Cl ions) are responsible for the conductivity upgrade. A Na–Sn/Fe [Fe(CN)6]3 solid state battery based on Na2.98Mg0.01SO4F0.95Cl0.05 electrolyte can reversibly run with a first discharge capacity as high as 91.0 mAh g−1 and a reversible capacity preserved at 77.0 mAh g−1. This result paves a way to novel anti-perovskite family of fluorinated sulfates as potential alkali metal ion solid electrolytes beyond already reported A3OX (A ​= ​Li or Na, X ​= ​heavy halogen or hydrogenide anions) anti-perovskites.

Ionic liquid based Fluoropolymer solid electrolytes for Lithium-ion batteries

Composite materials based on ionic liquids (ILs) / poly(vinylidene fluoride) (PVDF) and their copolymers have emerged as an interesting approach to develop high ionic conductivity solid polymer electrolytes (SPEs) for lithium-ion battery application.This work reports the development of SPEs based on fluoropolymers, PVDF and poly(vinylidene fluoride co-hexafluoropropylene), PVDF-HFP, containing different ILs: 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide ([EMIM][TFSI]) and 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]). The influence of IL type and content on the morphological, wettability, physical-chemical, thermal, mechanical and electrochemical properties were evaluated. It is shown that, independently of the polymer matrix, both ILs improve surface wettability and increase the polar β phase content and crystallinity degree of the polymers. The mechanical properties show that the incorporation of IL in the composites results in a plasticizing behaviour.Further, the [BMIM][SCN]/PVDF-HFP with 40 wt% IL content shows the best room temperature ionic conductivity of 0.15 mS.cm−1 with excellent electrochemical stability in the 0.0–5.0 V potential window. The initial discharge capacity value at C/8-rate is 148 mAh.g−1 and 124 mAh.g−1 for the [BMIM][SCN]/PVDF and [BMIM][SCN]/PVDF-HFP composites, respectively, with high coulombic efficiency (98%). At C/8-rate, batteries with [BMIM][SCN]/PVDF-HFP show the lowest capacity fade (16% after 50 cycles) of the prepared composites.Thus, it is demonstrated the suitability of developing SPEs based on IL and fluorinated polymers for the next generation of solid-state room temperature lithium-ion batteries.

Electrochemical Flash Sintering: A New Tool to Obtain All Solid-State Batteries in Few Seconds

Nowadays, inorganic All Solid-State Batteries (ASSBs) encounter a strong resurgence of scientific and technological interest stimulated by the discovery of new high conductivity solid electrolytes at room temperature (≥ 1 mS), as well as the development of fast Electrical Current Activated Sintering (ECAS) processes. One of the advantages of ASSBs is that they guarantee a unique safety due to the chemical and thermal stability of the materials. However, manufacturing dense ceramics requires sintering temperatures generally higher than 700 °C to lead to optimal mechanical and conductive properties. At these temperatures, the occurrence of undesired chemical reactions at the interfaces is an issue for electrochemical applications due to the formation of interdiffusion layers that block the charge transfer.For this purpose, Flash Sintering (FS) is very effective to densify conductive ceramics in a few seconds at significantly lower temperatures compared to conventional sintering.1,2 FS consists in making the current directly flows through the sample without neither the use of a conductive die nor the application of a charge. However, this technique requires a reversible electrochemical reaction to allow the charge transfer between the electronic conductor (i.e. the current collectors) and the ionic conductor (i.e. ceramic electrolyte).3 In the case of pure cationic conductors (Li+, Na+, K+, etc.), Pt electrodes which are commonly used for FS, are herein blocking electrodes preventing the current from flowing. A mixed cationic electronic conductor is then required to ensure the charge transfer reaction.Through this work, we demonstrate the feasibility of FS on Li+ ionic conductors such as Li1.3Al0.3Ti1.7(PO4)3 (LATP) or Li1.5Al0.3Ge1.5(PO4)3 (LAGP), using LiCoO2 (LCO) or LiNi1/3Mn1/3Co1/3O2 (NMC) mixed Li+/e- conductors as electrode materials. Using the concept of Electrochemical Flash Sintering, the “flash” event was obtained on two multi-component systems: LATP sandwiched between two pure LCO layers as electrodes and LATP sandwiched between two composite electrodes (LCO + LATP). Microstructural and chemical analyses were employed to characterise the densification at the vicinity of the interfaces. It is shown that a composite electrode both allows the flash to occur and prevents the delamination observed with pure LCO by lowering interfacial strains.4 This multi-material architecture turns out to be the one of an All-Solid-State Li-ion Battery, opening the path of using FS as a promising fast process to build functional multi-materials for energy storage devices. 1. Cologna, M.; Rashkova, B.; Raj, R. Flash sintering of nanograin zirconia in < 5 s at 850°C. J. Am. Ceram. Soc. 2010, 93, 3556–3559.2. Steil, M. C.; Marinha, D.; Aman, Y.; Gomes, J. R. C.; Kleitz, M. From conventional ac flash-sintering of YSZ to hyper-flash and double flash. J. Eur. Ceram. Soc. 2013, 33, 2093–3. Caliman, L.B.; Bouchet, R.; Gouvea, D.; Soudant, P.; Steil, M.C. Flash sintering of ionic conductors: the need of a reversible electrochemical reaction, J. Eur. Ceram. Soc. 2016, 36, 1253–1260.4. Lachal, M.; El. Khal, H.; Bouvard, D.; Chaix, J-M.; Bouchet, R.; Steil, M.C. Electrochemical Flash Sintering of advanced multi-materials for energy storage devices, J. Eur. Ceram. Soc. submitted. Figure 1

Dendrite-free lithium metal solid battery with a novel polyester based triblock copolymer solid-state electrolyte

Abstract Solid-state polymer Li metal batteries have been regarded as a promising candidate for next-generation batteries due to their high-energy densities provided by the Li metal and the improved safety provided by the solid electrolyte. Polyester is one attractive polymer host, which could be an alternative to polyether-based solid electrolyte due to its excellent lithium ion transport ability and wide electrochemical stability window. Here, a BAB-type triblock copolymer is synthesized with poly (propylene carbonate) as A-block and poly (e-caprolactone) as B-block. The triblock copolymer electrolyte exhibits a high ionic conductivity of 3 × 10−5 S cm−1 at 30 °C with a high lithium ion transference number (0.4) and an extremely wide electrochemical window (5 V). A highly stable interface against Li metal is maintained for more than 760 h at a current density of 0.1 mA cm−2. A LiFePO4 cathode based solid state battery delivers a high discharge capacity of 142 mA h g−1 at 0.05C, room temperature, and 161 mA h g−1 at 0.1C, 70 °C with a capacity retention of 90% after 200 cycles. To understand the excellent electrochemical performance, the morphology and chemical information at both anode and cathode interface are characterized and analyzed. The synthesis of this triblock copolymer demonstrates a new direction in developing high ionic conductivity solid polymer electrolyte for solid-state polymer batteries.

Submicron-Sized Nb-Doped Lithium Garnet for High Ionic Conductivity Solid Electrolyte and Performance of Quasi-Solid-State Lithium Battery.

The garnet Li7La3Zr2O12 (LLZO) has been widely investigated because of its high conductivity, wide electrochemical window, and chemical stability with regards to lithium metal. However, the usual preparation process of LLZO requires high-temperature sintering for a long time and a lot of mother powder to compensate for lithium evaporation. In this study submicron Li6.6La3Zr1.6Nb0.4O12 (LLZNO) powder―which has a stable cubic phase and high sintering activity―was prepared using the conventional solid-state reaction and the attrition milling process, and Li stoichiometric LLZNO ceramics were obtained by sintering this powder―which is difficult to control under high sintering temperatures and when sintered for a long time―at a relatively low temperature or for a short amount of time. The particle-size distribution, phase structure, microstructure, distribution of elements, total ionic conductivity, relative density, and activation energy of the submicron LLZNO powder and the LLZNO ceramics were tested and analyzed using laser diffraction particle-size analyzer (LD), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Electrochemical Impedance Spectroscopy (EIS), and the Archimedean method. The total ionic conductivity of samples sintered at 1200 °C for 30 min was 5.09 × 10−4 S·cm−1, the activation energy was 0.311 eV, and the relative density was 87.3%. When the samples were sintered at 1150 °C for 60 min the total ionic conductivity was 3.49 × 10−4 S·cm−1, the activation energy was 0.316 eV, and the relative density was 90.4%. At the same time, quasi-solid-state batteries were assembled with LiMn2O4 as the positive electrode and submicron LLZNO powder as the solid-state electrolyte. After 50 cycles, the discharge specific capacity was 105.5 mAh/g and the columbic efficiency was above 95%.

Gel Electrolyte Comprising Solvate Ionic Liquid and Methyl Cellulose

Self-standing, high conductivity solid iongel electrolytes with good thermal stability (Td ∼ 200 °C), mechanical properties, and an anodic stability up to 5 V were prepared using the solvate ionic ...