Promising Solid Electrolyte Research Articles

Achieving superior moisture-resistant and electrochemical properties of chlorine-rich Li-argyrodites via high oxygen dose

Cl-rich Li-argyrodites are promising solid electrolytes (SEs) used in all-solid-state Li batteries (ASSLBs) owing to the fast ion transport. However, they are unstable in the air and their compatibility to metallic Li still needs to be strengthened. Here, we improve these properties through O doping with a relatively high concentration. The high O solid solution in the argyrodite lattice is verified. The optimized Li5.7PS4.5O0.2Cl1.3 SE possesses an enhanced room temperature ionic conductivity. In parallel, in the sample with a relatively high oxygen dose, a Cl-O coexistence interface layer is revealed at the Li|SE interface region, associated with the formation of LiCl and Li3OCl interphases. The highest amount of Li3OCl appears also in the interface of Li5.7PS4.5O0.2Cl1.3 SE. Along with a more stable PS4-xOx unit, a proper O doing concentration is beneficial to mitigate the decomposition rate of SEs and to improve the compatibility of SE against Li metal. Moreover, Li5.7PS4.5O0.2Cl1.3 gains significantly enhanced air stability in contrast to the O-free sample. Consequently, the ASSLBs using both pristine and air-exposed Li5.7PS4.5O0.2Cl1.3 SE demonstrate decent electrochemical performance. In sharp contrast, the ASSLBs using the O-free argyrodite SE after air exposure cannot work for even one cycle. A high amount of O incorporation in Cl-rich Li-argyrodite SEs is thus a facile and effective route for achieving good overall performance including a high ionic conductivity, Li|SE interface stability, Li dendrite suppression capability, and notably, air stability.

Copper Thiophosphate (Cu3PS4) as an Electrode Material for Lithium Solid‐State Batteries with Lithium Thiophosphate (β–Li3PS4) Electrolyte

Lithium thiophosphate (β‐Li3PS4) is a promising solid electrolyte (SE) for solid‐state batteries (SSBs). A major limitation is its very narrow electrochemical stability window which is caused by redox reactions involving sulfur and phosphorous. As these redox processes can be reversible, thiophosphates can be also studied as electrode materials. Herein, the use of Cu3PS4 as an active electrode material for Li SSBs with β‐Li3PS4 as the SE is explored. Both compounds exhibit similarities in crystal structure and composition which may benefit their compatibility. An In/InLi alloy is used as the counter electrode. The influence of electrode composition and temperature (room temperature and 60 °C) on the cell behavior is investigated. For an electrode composition of Cu3PS4: β–Li3PS4: C65 = 40: 50: 10 wt%, the initial discharge capacity at 60 °C is 776 mAh g−1 which fades over 60 cycles to 508 mAh g−1 when cycled between 0.8 and 2.8 V (vs. Li+/Li) at 50 mA g−1 (254.8 μA cm−2). Analysis by X‐ray diffraction and X‐ray photoelectron spectroscopy shows that Cu3PS4 irreversibly decomposes during lithiation. During cycling, the redox activity is found to be due to Cu2S and S8 redox.

MgSc2Se4 Solid Electrolyte for Rechargeable Mg Batteries

MgSc2Se4 is among the most promising magnesium-ion solid electrolyte, as it possesses a high room temperature Mg+2 conductivity (~ 10-4 S/cm). However, MgSc2Se4 is also demonstrating a considerably high electronic conductivity (10-5 to 10-8 S/cm). Such high electronic conductivity restricts the applications of the material in all solid-state Mg-ion batteries. Efforts to lower the electronic conductivity via the enrichment of the material with selenium aliovalent doping, were not successful thus far. This suggests that the electronic conductivity may follow a model, which is different from a common model of charge transfer by electrons in a conduction band of the wide band gap semiconductor MgSc2Se4. Here, we will discuss and present data showing that the electronic transport in the Mg-Sc-Se ceramic is facilitated via the Berthelot-type conductivity mechanism. This suggests an electronic transport through a low-conducting matrix stuffed with nano-scaled free electron-containing regions. These inclusions are well-distributed across the Mg-Sc-Se, and the electronic transport takes place via electron tunneling between these conductive regions, through low-conducting matrix spacers. It is shown that these conductive zones, being comprised of elemental metallic Sc and ScSe mix, behave as a metallic-type electronic conductor. The nature of these conductive inclusions and the synthetic parameters controlling the appearance of such conductive areas will be discussed, as well as routes to minimize their formation.

The Impact of Intergrain Phases on the Ionic Conductivity of the LAGP Solid Electrolyte Material Prepared by Spark Plasma Sintering.

Li1.5Al0.5Ge1.5(PO4)3 (LAGP) is a promising oxide solid electrolyte for all-solid-state batteries due to its excellent air stability, acceptable electrochemical stability window, and cost-effective precursor materials. However, further improvement in the ionic conductivity performance of oxide solid-state electrolytes is hindered by the presence of grain boundaries and their associated morphologies and composition. These key factors thus represent a major obstacle to the improved design of modern oxide based solid-state electrolytes. This study establishes a correlation between the influence of the grain boundary phases, their 3D morphology, and compositions formed under different sintering conditions on the overall LAGP ionic conductivity. Spark plasma sintering has been employed to sinter oxide solid electrolyte material at different temperatures with high compacity values, whereas a combined potentiostatic electrochemical impedance spectroscopy, 3D FIB-SEM tomography, XRD, and solid-state NMR/materials modeling approach provides an in-depth analysis of the influence of the morphology, structure, and composition of the grain boundary phases that impact the total ionic conductivity. This work establishes the first 3D FIB-SEM tomography analysis of the LAGP morphology and the secondary phases formed in the grain boundaries at the nanoscale level, whereas the associated 31P and 27Al MAS NMR study coupled with materials modeling reveals that the grain boundary material is composed of Li4P2O7 and disordered Li9Al3(P2O7)3(PO4)2 phases. Quantitative 31P MAS NMR measurements demonstrate that optimal ionic conductivity for the LAGP system is achieved for the 680 °C SPS preparation when the disordered Li9Al3(P2O7)3(PO4)2 phase dominates the grain boundary composition with reduced contributions from the highly ordered Li4P2O7 phases, whereas the 27Al MAS NMR data reveal that minimal structural change is experienced by each phase throughout this suite of sintering temperatures.

Self-Assembled Lanthanum Oxide Nanoflakes by Electrodeposition Technique for Resistive Switching Memory and Artificial Synaptic Devices.

In recent years, many metal oxides have been rigorously studied to be employed as solid electrolytes for resistive switching (RS) devices. Among these solid electrolytes, lanthanum oxide (La2 O3 ) is comparatively less explored for RS applications. Given this, the present work focuses on the electrodeposition of La2 O3 switching layers and the investigation of their RS properties for memory and neuromorphic computing applications. Initially, the electrodeposited La2 O3 switching layers are thoroughly characterized by various analytical techniques. The electrochemical impedance spectroscopy (EIS) and Mott-Schottky techniques are probed to understand the in situ electrodeposition, RS mechanism, and n-type semiconducting nature of the fabricated La2 O3 switching layers. All the fabricated devices exhibit bipolar RS characteristics with excellent endurance and stable retention. Moreover, the device mimics the various bio-synaptic properties such as potentiation-depression, excitatory post-synaptic currents, and paired-pulse facilitation. It is demonstrated that the fabricated devices are non-ideal memristors based on double-valued charge-flux characteristics. The switching variation of the device is studied using the Weibull distribution technique and modeled and predicted by the time series analysis technique. Based on electrical and EIS results, a possible filamentary-based RS mechanism is suggested. The present results assert that La2 O3 is a promising solid electrolyte for memory and brain-inspired applications.

Solid Hybrid Electrolyte Featuring a Vertically Aligned Li6.4La3.0Zr1.4Ta0.6O12 Membrane for All-Solid-State Lithium Batteries.

All-solid-state lithium batteries (ASSLBs) with enhanced safety are considered one of the most promising substitutes for liquid electrolyte-based Li-ion batteries. However, many properties of solid electrolytes, such as ionic conductivity, film formability, and electrochemical, mechanical, thermal, and interfacial stability need to be improved for their practical application. In this study, a vertically aligned Li6.4La3.0Zr1.4Ta0.6O12 (LLZO) membrane with finger-like microvoids was prepared using processes involving phase inversion and sintering. A hybrid electrolyte was then obtained by infusing the LLZO membrane with a solid polymer electrolyte based on poly(ε-caprolactone). The solid hybrid electrolyte (SHE) was a flexible thin film with high ionic conductivity, superior electrochemical stability, high Li+ transference number, enhanced thermal stability, and improved Li metal electrode-solid electrolyte interfacial stability. A solid-state Li/LiNi0.78Co0.10Mn0.12O2 cell assembled with the hybrid electrolyte exhibited good cycling performance, in terms of discharge capacity, cycling stability, and rate capability. Accordingly, the SHE using a vertically aligned LLZO membrane is a promising solid electrolyte for realizing safe, high-performance ASSLBs.

Enhanced resistive switching of silver copper iodide thin films prepared by interfacial phase formation

Resistive random-access memory (ReRAM), an alternative to conventional charge storage memory, employs the switching of a resistive material between high-resistance and low-resistance states, which can be generated by the formation/dissolution of metal filaments bridging the two electrodes in the cell. Silver iodide (AgI) is a promising solid electrolyte for ReRAM cells, but its application is hindered by poor photostability and low electrical conductivity. Herein, a Cu-substituted β-AgI system, β′-Ag0.7Cu0.3I, was successfully prepared via sequential deposition of a Cu metal layer onto a AgI thin film by a galvanic reaction, which induced the spontaneous incorporation of Cu+ cations into the AgI lattice. Cu substitution at the Cu–AgI heterojunction interface is a novel way to modulate the chemical composition and improve the resistive switching properties of intrinsic polycrystalline AgI thin films. We compared the resistive switching properties of a ReRAM thin film devices based on β′-Ag0.7Cu0.3I with those based on pristine β-AgI. This device exhibited enhanced performance with high ON/OFF ratio (∼104) and low working voltage compared with the β-AgI-based device. These results strongly suggest that binary metal halide materials can serve as simple model systems for the efficient formation of metal filaments and have potential low-cost, low-power memory applications.

Composition, structure and electrochemical performance of LiSiPSCl electrolyte with Li/Li-In anodes in all-solid-state batteries

The lithium silicon phosphor sulfo-chloride (LiSiPSCl) with a Li10GeP2S12-type structure is one of the most promising solid electrolytes (SEs) for all-solid-state lithium-ion batteries (ASSLIBs) due to its currently highest ionic conductivity at RT. In this work, three kinds of LiSiPSCl electrolytes, i.e. Li7.59(10)Si1.95(9)P1.65(7)S11.64(1)Cl0.36(1) (SE-450), Li7.67(12)Si1.90(1)P1.67(1)S11.61(2)Cl0.39(2) (SE-475) and Li7.58(5)Si1.75(4)P1.79(2)S11.54(4)Cl0.46(4) (SE-500), were prepared at 450 / 475 / 500 °C for 8 h through a solid-state method. The assembling of blocking / symmetrical / semi-blocking cells and ASSLIBs, and electrochemical measurements were carried out by coupling the three SEs with two kinds of anodes (Li metal and Li-In alloy) and one cathode of LiNbO3-coated LiNi0.8Co0.1Mn0.1O2 (NCM@LNO). Studies were focused on the relationship among chemical compositions, phase structures and electrochemical properties, as well as the electrolyte/electrode interfacial stability. Results show that LiSiPSCl electrolytes had favorable interfacial stability with Li-In anode and exhibited low polarization voltage (< 20 mV) and decomposition current (< 0.01 mA). The optimized NCM@LNO//SE-475//Li-In of ASSLIBs exhibited a stable long-term cycle performance with a capacity retention of 97.0% (128.4 mAh g−1) after 50 cycles and 81.1% (107.4 mAh g−1) after 100 cycles at 0.1 C. In addition, it exhibited a good rate performance while its capacity retention remained 99.3% (140.6 mAh g−1) after 39 cycles at 0.05 / 0.1 / 0.2 / 0.5 / 0.05 C.

TiO2‐Induced Conversion Reaction Eliminating Li2CO3 and Pores/Voids Inside Garnet Electrolyte for Lithium–Metal Batteries

AbstractGarnet Li7La3Zr2O12 (LLZO) is regarded as a promising solid electrolyte due to its high Li+ conductivity and excellent chemical stability, but suffers from grain boundary resistance and porous structure which restrict its practical applications in lithium–metal batteries. Herein, a novel and highly efficient TiO2‐induced conversion strategy is proposed to generate Li ion‐conductive Li0.5La0.5TiO3, which can simultaneously eliminate the pre‐existing pores/voids and contamination Li2CO3. The Li/LLZTO‐5TiO2/Li symmetric cell exhibits a high critical current density of 1.1 mA cm−2 at 25°C, and the long‐term lithium cycling stability of over 1500 h at 0.1 mA cm−2. More importantly, the excellent performance of LLZTO‐5TiO2 electrolyte is verified by LiCoO2/LiFePO4 coupled full cells. For example, The LiCoO2 coupled full cell exhibits a significant discharge rate capacity of 108 mAh g−1 at 0.1 C, and a discharge capacity retention rate of 91.23% even after 150 cycles of charge and discharge. COMSOL Multiphysics and density functional theory calculation reveal that LLZTO‐5TiO2 electrolyte has a strong lithium affinity and uniform Li ions distribution, which can improve the cycle stability of Li–metal batteries by preventing dendrite growth.

Development of a Solid Bio‐Electrolyte from a Seaweed Extract – Polyvinyl Alcohol Blend for Primary Mg‐Ion Conducting Batteries

AbstractA novel solid bio‐electrolyte from seaweed acts as a potential candidate for electrolytes in batteries by solution casting technique. The ethanol extract of seaweed Sargassum Muticum (SME) is blended with PVA to prepare the bio‐membrane and along with MgCl2 as the ionic provider, a solid bio‐electrolyte is produced. The ionic conductivity of the prepared bio‐membrane, 1 g SME+0.8 g PVA is 1.57×10−6 S cm−1. XRD analysis affirms the amorphous nature of the prepared bio‐electrolytes and the highest degree of amorphous nature is apparent for the composition of 1 g SME+0.8 g PVA+0.7 wt% MgCl2. Complex formation between the SME, polyvinyl alcohol, and the added charge carrier has been made evident from the FTIR technique. Thermal properties of the bio‐electrolytes by differential scanning calorimetry (DSC) are supported by the low Tg. Electrochemical impedance analysis for the prepared bio‐electrolytes and the maximum ionic conductivity of 2.22×10−3 S cm−1 is exhibited by 1 g SME+0.8 g PVA+0.7 wt% MgCl2 membrane. A primary magnesium‐ion conducting battery has been constructed with the highest conducting bio‐electrolyte membrane and an open circuit voltage of 2.18 V validates the application of this bio‐membrane as a promising solid electrolyte for energy storage devices.

Electrochemical Stability Window and Electrolyte Breakdown Mechanisms of Lithium Lanthanum Titanate

Perovskite-type La0.57Li0.29TiO3 (LLTO) is a promising solid electrolyte material with high Li-ion conductivity. However, its experimental electrochemical stability window is not precisely known, and thus the compatibility with potential electrode materials is partly unclear. In this contribution, we present results from electrochemical and analytical experiments to elucidate the stability of LLTO when being polarized with Li-ion-blocking Pt electrodes. Above 2.5 V, a darkened color front starts moving from the cathode to the anode, leading to electrolyte degradation. While first-principles calculations predict the appearance of new phases as decomposition products, we find zones with modified defect chemical properties originating from the anode and cathode. The darkened zone forming at the cathode contains Ti3+ polarons with high mobility, which leads to a mixed ion-electron conductivity, already for a very small Li excess concentration. Next to the anode a spatially very confined, weakly conductive Li depletion zone forms. The spatially confined but substantial Li depletion near the anode could be quantified by analytical laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). In contrast to first-principles calculations, no new phases were found near the anode, according to synchrotron-based grazing incidence XRD measurements.

Amorphous Phase Induced Lithium Dendrite Suppression in Glass-Ceramic Garnet-Type Solid Electrolytes.

Lithium metal-based solid-state batteries (SSBs) have attracted much attention due to their potentially higher energy densities and improved safety compared with lithium-ion batteries. One of the most promising solid electrolytes, garnet-type Li7La3Zr2O12 (LLZO), has been investigated intensively in recent years. It enables the use of a lithium metal anode, but its application is still challenging because of lithium dendrites that grow at voids, cracks, and grain boundaries of sintered bodies during cycling of the battery cell. In this work, glass-ceramic Ta-doped LLZO produced in a unique melting process was investigated. Upon cooling, an amorphous phase is generated intrinsically, whose composition and fraction are adjusted during the process. Herein, it was set to about 4 wt % containing Li2O and a Li2O-SiO2 phase. During sintering, it was shown to segregate into the grain boundaries and decrease porosity via liquid phase sintering. Sintering temperature and sintering time were found to be reduced compared with the LLZO fabricated by a solid-state reaction while maintaining high density and ionic conductivity. The glass-ceramic sintered at 1130 °C for 0.5 h showed a room-temperature ionic conductivity of 0.64 mS cm-1. Most importantly, the evenly distributed amorphous phase along the grain boundaries effectively hinders lithium dendrite growth. Besides mechanically blocking pores and voids, it helps to prevent inhomogeneous distribution of current density. The critical current density (CCD) of the Li|LLZTO|Li symmetric cell was determined as 1.15 mA cm-2, and in situ lithium plating experiments in a scanning electron microscope revealed superior dendrite stability properties. Therefore, this work provides a promising strategy to prepare a dense and dendrite-suppressing solid electrolyte for future implementation in SSBs.

Reactive Magnesium Nitride Additive: A Drop-in Solution for Lithium/Garnet Wetting in All-Solid-State Batteries.

Garnet oxides such as Li6.4 La3 Zr1.4 Ta0.6 O12 (LLZTO) are promising solid electrolyte materials for all-solid-state lithium-metal batteries because of high ionic conductivity, low electronic leakage, and wide electrochemical stability window. While LLZTO has been frequently discussed to be stable against lithium metal anode, it is challenging to achieve and maintain good solid-on-solid wetting at the metal/ceramic interface in both processing and extended electrochemical cycling. Here we address the challenge by a powder-form magnesium nitride additive, which reacts with the lithium metal anode to produce well-dispersed lithium nitride. The in situ formed lithium nitride promotes reactive wetting at the Li/LLZTO interface, which lowers interfacial resistance, increases critical current density (CCD), and improves cycling stability of the electrochemical cells. The additive recipe has been diversified to titanium nitride, zirconium nitride, tantalum nitride, and niobium nitride, thus supporting the general concept of reactive dispersion-plus-wetting. Such a design can be extended to other solid-state devices for better functioning and extended cycle life.

Reactive Magnesium Nitride Additive: A Drop‐in Solution for Lithium/Garnet Wetting in All‐Solid‐State Batteries

AbstractGarnet oxides such as Li6.4La3Zr1.4Ta0.6O12 (LLZTO) are promising solid electrolyte materials for all‐solid‐state lithium‐metal batteries because of high ionic conductivity, low electronic leakage, and wide electrochemical stability window. While LLZTO has been frequently discussed to be stable against lithium metal anode, it is challenging to achieve and maintain good solid‐on‐solid wetting at the metal/ceramic interface in both processing and extended electrochemical cycling. Here we address the challenge by a powder‐form magnesium nitride additive, which reacts with the lithium metal anode to produce well‐dispersed lithium nitride. The in situ formed lithium nitride promotes reactive wetting at the Li/LLZTO interface, which lowers interfacial resistance, increases critical current density (CCD), and improves cycling stability of the electrochemical cells. The additive recipe has been diversified to titanium nitride, zirconium nitride, tantalum nitride, and niobium nitride, thus supporting the general concept of reactive dispersion‐plus‐wetting. Such a design can be extended to other solid‐state devices for better functioning and extended cycle life.

Effects of LiPON Incorporation on the Structures and Properties of Mixed Oxy-Sulfide-Nitride Glassy Solid Electrolytes.

Glassy solid electrolytes (GSEs) are promising solid electrolytes in the development of all solid-state batteries. Mixed oxy-sulfide nitride (MOSN) GSEs combine the high ionic conductivity of sulfide glasses, the excellent chemical stability of oxide glasses, and the electrochemical stability of nitride glasses. However, the reports on the synthesis and characterization of these novel nitrogen containing electrolytes are quite limited. Therefore, the systematic incorporation of LiPON during glass synthesis was used to explore the effects of nitrogen and oxygen additions on the atomic-level structures in the glass transition (Tg) and crystallization temperature (Tc) of MOSN GSEs. The MOSN GSE series 58.3Li2S + 31.7SiS2 + 10[(1 - x)Li0.67PO2.83 + x LiPO2.53N0.314], x = 0.0, 0.06, 0.12, 0.2, 0.27, 0.36, was prepared by melt-quench synthesis. Differential scanning calorimetry was used to determine the Tg and Tc values of these glasses. Fourier transformation-infrared, Raman, and magic angle spinning nuclear magnetic resonance spectroscopies were used to examine the short-range order structures of these materials. X-ray photoelectron spectroscopy was conducted on the glasses to further understand the bonding environments of the doped nitrogen. Finally, N and S elemental analyses were used to confirm the composition of these GSEs. These results are used to elucidate the structure of these glasses and to understand the thermal property impact oxygen and nitrogen doping in these GSEs.

Theoretical Design of Defects as a Driving Force for Ion Transport in Li3OBr Solid Electrolyte

Due to ever‐increasing concerns about safety issues in using Li ionic batteries, solid electrolytes have extensively explored. The Li‐rich anti‐perovskite Li3OBr has been considered as a promising solid electrolyte candidate, but it still suffers challenges to achieve a high ionic conductivity owing to the high intrinsic symmetry of the crystal lattice. Herein, we presented a design strategy that introduces various point defects and grain boundaries to break the high lattice symmetry of Li3OBr crystal, and their effect and microscopic mechanism of promoting the migration of Li‐ion were explored theoretically. It has been found that are the dominant defects responsible for the fast Li‐ion diffusion in bulk Li3OBr and its surface, but they are easily trapped by the grain boundaries, leading to the annihilating of the Frenkel defect pair and thus limits the diffusion at the grain boundaries. The defect near the grain boundaries can effectively drive across the grain boundary, thereby converting the carrier of Li+ migration from in the bulk and surface to at the grain boundary, and thus improving the ionic conductivity in the whole Li3OBr crystal. This work provides a comprehensive insight into the Li+ transport and conduction mechanism in the Li3OBr electrolyte. It opens a new way of improving the conductivity for all‐solid‐state Li electrolyte material through the defect design.

Improving ionic conductivity of von-Alpen-type NASICON ceramic electrolytes via magnesium doping

NASICON (sodium (Na) superionic conductor) compounds have attracted considerable attention as promising solid electrolyte materials for advanced Na-based batteries. In this study, we investigated the improvement in ionic conductivities of von-Alpen-type NASICON (vA-NASICON) ceramic electrolytes by introducing a magnesium ion (Mg²⁺) as a heterogeneous element. The optimal Mg-doped vA-NASICON exhibited a high ionic conductivity of 3.64×10⁻³ S·cm⁻¹, which was almost 80% higher than that of un-doped vA-NASICON. The changes in physicochemical properties of the vA-NASICONs through the Mg introduction were systematically analyzed, and their effects on the ionic conductivities of the vA-NASICON were studied in detail. When the optimal ratio of Mg²⁺ was used in a synthetic process, the relative density (96.6%) and grain boundary ionic conductivity (<i>σ</i>_gb) were maximized, which improved the total ionic conductivity (<i>σ</i>_t) of the vA-NASICON. However, when Mg²⁺ was introduced in excess, the ionic conductivity decreased because of the formation of an undesired sodium magnesium phosphate (Na_<i>x</i>Mg_<i>y</i>PO₄) secondary phase. The results of this study are expected to be effectively applied in the development of advanced sodium-based solid electrolytes with high ionic conductivities.

Lithium Ion Transport Environment by Molecular Vibrations in Ion‐Conducting Glasses

Controlling Li ion transport in glasses at atomic and molecular levels is key to realizing all‐solid‐state batteries, a promising technology for electric vehicles. In this context, Li3PS4 glass, a promising solid electrolyte candidate, exhibits dynamic coupling between the Li+ cation mobility and the PS43− anion libration, which is commonly referred to as the paddlewheel effect. In addition, it exhibits a concerted cation diffusion effect (i.e., a cation–cation interaction), which is regarded as the essence of high Li ion transport. However, the correlation between the Li+ ions within the glass structure can only be vaguely determined, due to the limited experimental information that can be obtained. Here, this study reports that the Li ions present in glasses can be classified by evaluating their valence oscillations via Bader analysis to topologically analyze the chemical bonds. It is found that three types of Li ions are present in Li3PS4 glass, and that the more mobile Li ions (i.e., the Li3‐type ions) exhibit a characteristic correlation at relatively long distances of 4.0–5.0 Å. Furthermore, reverse Monte Carlo simulations combined with deep learning potentials that reproduce X‐ray, neutron, and electron diffraction pair distribution functions showed an increase in the number of Li3‐type ions for partially crystallized glass structures with improved Li ion transport properties. Our results show order within the disorder of the Li ion distribution in the glass by a topological analysis of their valences. Thus, considering the molecular vibrations in the glass during the evaluation of the Li ion valences is expected to lead to the development of new solid electrolytes.

A promising composite solid electrolyte of garnet-type LLZTO and succinonitrile in thermal polyurethane matrix for all-solid-state lithium-ion batteries

For solid-state electrolyte in lithium-ion batteries, high crystal boundary impedance leads to tough electrolyte-electrode interfacial issues. Here, we introduce garnet Li6.4La3Zr1.4Ta0.6O12 (LLZTO) nanoparticles and succinonitrile (SN) into thermal polyurethane (TPU) to fabricate a composite solid-state electrolyte (TPU/LLZTO/SN), achieving high ionic conductivity of 6.452 × 10−4 S cm−1. The TPU polymer with specific soft and hard segments allows lithium ions fast transport and holds good mechanical strength as the electrolyte matrix. The ionic conductor LLZTO further improves the ionic conductivity and mechanical property of the composite electrolyte membrane. Additional SN supplies the electrolyte’ wide electrochemical stabilization window, and enhances the metallic lithium compatibility of the TPU matrix. As a result, the as prepared TPU/LLZTO/SN electrolyte presents high lithium ions transference number of 0.64, and also good mechanical property.

A novel promotion strategy for microstructure and electrical performance of garnet electrolytes via Li4GeO4 additive

Cubic Li6.4La3Zr1.4Ta0.6O12 (c-LLZTO) electrolyte is one of the most promising solid electrolytes. However, it is rather difficult to promote its electrical performance while reducing process parameters. Therefore, Li4GeO4 is applied as the additive in liquid sintering of LLZTO ceramics in this study. The LLZTO@Li4GeO4/Li2O composite electrolyte sintered at 1180 °C for 3 h performs a significantly promoted microstructure and electrical performance, the ionic conductivity of which reaches 5.77 × 10−4 S cm−1 at 25 °C. The Li4GeO4/Li2O eutectic phase contributed prominently, in which the high concentration of Li+ seaming the LLZTO grains tightly. Meanwhile, Li+ conduction in the consecutive conductive pathways constructed by [GeO4] groups among the grains was greatly stimulated. With the modification of the grain boundary, an improved garnet electrolytes/Li anode interface performance is produced. The Li/Au|LLZTO@Li4GeO4/Li2O|Au/Li symmetrical cell is able to cycle stably for more than 500 h at the current density of 0.1 mA cm−2 at room temperature.