Management of heat during charging and discharging of Li-ion batteries is critical for their safety, reliability, and performance. Understanding the thermal conductivity of the materials comprising batteries is crucial for controlling the temperature and temperature distribution in batteries. This work provides systemic quantitative measurements of the thermal conductivity of three important classes of solid electrolytes (oxides, sulfides, and halides) over the temperature range 150-350 K. Studies include the oxides Li1.5Al0.5Ge1.5(PO4)3 and Li6.4La3Zr1.4Ta0.6O12, sulfides Li2S-P2S5, Li6PS5Cl, and Na3PS4, and halides Li3InCl6 and Li3YCl6. Thermal conductivities of sulfide and halide solid electrolytes are in the range 0.45-0.70 W m-1 K-1; thermal conductivities of Li6.4La3Zr1.4Ta0.6O12 and Li1.5Al0.5Ge1.5(PO4)3 are 1.4 W m-1 K-1 and 2.2 W m-1 K-1, respectively. For most of the solid electrolytes studied in this work, the thermal conductivity increases with increasing temperature; i.e., the thermal conductivity has a glass-like temperature dependence. The measured room-temperature thermal conductivities agree well with the calculated minimum thermal conductivities indicating the phonon mean-free-paths in these solid electrolytes are close to an atomic spacing. We attribute the low, glass-like thermal conductivity of the solid electrolytes investigated to the combination of their complex crystal structures and the atomic-scale disorder induced by the materials processing methods that are typically needed to produce high ionic conductivities.
Room-temperature (RT) conductivity of most candidates for solid electrolytes of miniaturized lithium-ion batteries is still 1-2 orders of magnitude below commercial requirements, therefore several approaches are being pursued aiming the enhancement of such values. In this letter, we report for the first time direct theoretical evidence that epitaxial strain can be an efficient tool to reach this goal.
A Comparative Study of Molecular Dynamics Approaches for Simulating Ionic Conductivity in Solid Lithium Electrolytes
Université de Montréal（蒙特利尔大学）；Mila – Quebec AI Institute（米拉-魁北克人工智能研究所）；National Research Council Canada（加拿大国家研究委员会）；Institut Courtois, Université de Montréal（蒙特利尔大学库尔图瓦研究所）
Design novel solid oxide electrolyte with enhanced ionic conductivity forms one of the Holy Grails in the field of materials science due to its great potential for wide range of energy applications. Conventional solid oxide electrolyte typically requires elevated temperature to activate the ionic transportation, while it has been increasing research interests to reduce the operating temperature due to the associated scientific and technological importance. Here, we report a conceptually new solid oxide electrolyte, HSrCoO2.5, which shows an exceptional enhanced proton conductivity at low tempe…
The electrochemical switching of SrCoOx-based non-volatile memory with thin-film-transistor structure was examined by using liquid-leakage-free electrolytes with different conductivity (s) as the gate insulator. We first examined leakage-free water, which is incorporated in the amorphous (a-) 12CaO 7Al2O3 film with nanoporous structure (CAN), but the electrochemical oxidation/reduction of SrCoOx layer required the application of high gate voltage (Vg) up to 20 V for a very long retention-time (t) 40 minutes, primarily due to the low s (2.0 x 10-8 S cm-1 at RT) of leakage-free water.We then con…
Electrical conductivity of dry, slow cooled (AgPO$_3$)$_{1-x}$(AgI)$_x$ glasses is examined as a function of temperature, frequency and glass composition. From these data compositional trends in activation energy for conductivity E$_A$(x), Coulomb energy E$_c$(x) for Ag$^+$ ion creation, Kohlrausch stretched exponent $β$(x), low frequency ($\varepsilon_s$(x)) and high-frequency ($\varepsilon_\infty$(x)) permittivity are deduced. All parameters except E$_c$(x) display two compositional thresholds, one near the stress transition, x = x$_c$(1)= 9%, and the other near the rigidity transition, x = …
Unraveling impacts of polycrystalline microstructures on ionic conductivity of ceramic electrolytes by computational homogenization and machine learning
We have carried out time--domain electrostatic force spectroscopy on two different ion conducting glasses using an atomic force microscope. We compare the electrostatic force spectroscopic data obtained at different temperatures with macroscopic electrical data of the glasses. The overall consistency of the data shows that electrostatic force spectroscopy is capable of probing the ion dynamics and transport in nanoscopic subvolumes of the samples.
We use rigorous group-theoretic techniques and molecular dynamics to investigate the connection between structural symmetry and ionic conductivity in the garnet family of solid Li-ion electrolytes. We identify new ordered phases and order-disorder phase transitions that are relevant for conductivity optimization. Ionic transport in this materials family is controlled by the frustration of the Li sublattice caused by incommensurability with the host structure at non-integer Li concentrations, while ordered phases explain regions of sharply lower conductivity. Disorder is therefore predicted to …
Synergistic Interface Stability and High Room-Temperature Ionic Conductivity for Wide-Temperature All-Solid-State Batteries Based on Li6+xSixSb1-xS5I Electrolytes
Solid polymer electrolytes for lithium batteries promise improvements in safety and energy density if their conductivity can be increased. Nanostructured block copolymer electrolytes specifically have the potential to provide both good ionic conductivity and good mechanical properties. This study shows that the previously neglected nanoscale composition of the polymer electrolyte close to the electrode surface has an important effect on impedance measurements, despite its negligible extent compared to the bulk electrolyte. Using standard stainless steel blocking electrodes, the impedance of li…
The argyrodite sulfides are getting more and more attractive as highly promising solid-state electrolytes (SSEs) for high-performance all-solid-state batteries (ASSBs), owing to their high ionic conductivity, adequate plasticity, and decent mechanical strength. However, their poor incompatibility with Li metal anode and high voltage cathodes and as well as serious sensitivity to air significantly hinder their practical applications. Herein, we have devised an effective strategy to overcome these challenging shortcomings through modification of chalcogen chemistry under the guidance of theoreti…
The PEO3:LiCF3SO3 polymer electrolyte has attracted significant research due to its enhanced stability at the lithium/polymer interface of high conductivity polymer batteries. Experimental studies have shown that, depending on the preparation conditions, both the PEO3:LiCF3SO3 crystalline complex and the PEO3:LiCF3SO3 amorphous phase can be formed. However, previous theoretical investigations focused on the short chain amorphous PEO3:LiCF3SO3 system. We report ab initio density-functional-theory calculations of crystalline PEO3:LiCF3SO3. The calculated results about the bonding configuration, …
Lithium thiophosphates (LPS) with the composition (Li$_2$S)$_x$(P$_2$S$_5$)$_{1-x}$ are among the most promising prospective electrolyte materials for solid-state batteries (SSBs), owing to their superionic conductivity at room temperature ($>10^{-3}$ S cm$^{-1}$), soft mechanical properties, and low grain boundary resistance. Several glass-ceramic (gc) LPS with different compositions and good Li conductivity have been previously reported, but the relationship between composition, atomic structure, stability, and Li conductivity remains unclear due to the challenges in characterizing non-cryst…
The addition of filler particles to polymer electrolytes is known to increment their ionic conductivity (IC). A detailed understanding of how the interactions between the constituent materials are responsible for the enhancement, remains to be developed. A significant contribution is ascribed to an increment of the polymer amorphous fraction, induced by the fillers, resulting in the formation of higher ionic conductivity channels in the polymer matrix. However, the dependence of IC on the particle weight load and its composition on the polymer morphology is not fully understood. This work inve…
Blend solid polymer electrolyte based on PEO, PVP complexed with lithium LiBOB were synthesized by solution cast technique and impact of LiBOB on the morphology, structure, and electrochemical properties is examined. The XRD and FESEM analysis reveals the enhancement of amorphous content on salt addition. The FTIR spectroscopy evidences the complex formation. The ionic conductivity for optimized system was two order higher than salt free system, i.e. ~0.5x10-5 S cm-1 (@RT) and increases to ~0.65 mS cm-1 (@100 oC) for O/Li=16 and temperature dependent conductivity follows Arrhenius nature. The …
Nonlinear conductivity effects are studied experimentally and theoretically for thin samples of disordered ionic conductors. Following previous work in this field the {\it experimental nonlinear conductivity} of sodium ion conducting glasses is analyzed in terms of apparent hopping distances. Values up to 43 Åare obtained. Due to higher-order harmonic current density detection, any undesired effects arising from Joule heating can be excluded. Additionally, the influence of temperature and sample thickness on the nonlinearity is explored. From the {\it theoretical side} the nonlinear conductivi…
Optimizing Ti substitution for the enhanced densification, ionic conductivity, and microstructure of garnet-type Li$_7$La$_3$Zr$_2$O$_{12}$ solid electrolytes
Visvesvaraya National Institute of Technology（维斯瓦萨瓦尔亚国家理工学院）
Molecular dynamics simulations are a powerful tool to study diffusion processes in battery electrolyte and electrode materials. From a single molecular dynamics simulation many properties relevant to diffusion can be obtained, including the diffusion path, attempt frequency, activation energies, and collective diffusion processes. These detailed diffusion properties provide a thorough understanding of diffusion in solid electrolytes, and provides direction for the design of improved solid electrolyte materials. Here a thorough analysis methodology is developed, and applied to DFT MD simulation…
Data-driven Prediction of Ionic Conductivity in Solid-State Electrolytes with Machine Learning and Large Language Models
School of Chemical Engineering, Pusan National University（釜山国立大学化学工程学院）；Department of Materials Science and Engineering, Pukyong National University（釜庆国立大学材料科学与工程系）；Graduate School of Data Science, Pusan National University（釜山国立大学数据科学研究生院）
The properties of the mixed system LiBH4 LiCl P2S5 are studied with respect to all-solid-state batteries. The studied material undergoes an amorphization upon heating above 601C, accompanied with increased Li+ conductivity beneficial for battery electrolyte applications. The measured ionic conductivity is 10-3 Scm-1 at room temperature with an activation energy of 0.40(2) eV after amorphization. Structural analysis and characterization of the material suggest that BH4 groups and PS4 may belong to the same molecular structure, where Cl ions interplay to accommodate the structural unit. Thanks t…
The conductivity of ionic solutions is arguably their most important trait, being widely used in electrochemical, biochemical, and environmental applications. The Debye-Hückel-Onsager theory successfully predicts the conductivity at very low ionic concentrations of up to a few millimolars, but there is no well-established theory applicable at higher concentrations. We study the conductivity of ionic solutions using a stochastic density functional theory, paired with a modified Coulomb interaction that accounts for the hard-core repulsion between the ions. The modified potential suppresses unph…
The introduction of A-site vacancies in SrTiO3 results in a glass-like thermal conductivity while Nb substituted samples maintains good electrical conductivity. This unexpected result brings SrTiO3 one step closer to being a high-performing phonon-glass electron-crystal thermoelectric material.
Many plastic crystals, molecular solids with long-range, center-of-mass crystalline order but dynamic disorder of the molecular orientations, are known to exhibit exceptionally high ionic conductivity. This makes them promising candidates for applications as solid-state electrolytes, e.g., in batteries. Interestingly, it was found that the mixing of two different plastic-crystalline materials can considerably enhance the ionic dc conductivity, an important benchmark quantity for electrochemical applications. An example is the admixture of different nitriles to succinonitrile, the latter being …
Finding new ionic conductors that enable significant advancements in the development of energy-storage devices is a challenging goal of current material science. Aside of material classes as ionic liquids or amorphous ion conductors, the so-called plastic crystals (PCs) have been shown to be good candidates combining high conductivity and favourable mechanical properties. PCs are formed by molecules whose orientational degrees of freedom still fluctuate despite the material exhibits a well-defined crystalline lattice. Here we show that the conductivity of Li+ ions in succinonitrile, the most p…
The use of oxide glasses is pervasive throughout everyday amenities and commodities. Such glasses are typically electrical insulators, and endowing them with electrical conductivity without changing their salutary mechanical properties, weight, or thermoformability enables new applications in multifunctional utensils, smart windows, and automotive parts. Previous strategies to impart electrical conductivity include modifying the glass composition or forming a solid-in-solid composite of the glass and a conductive phase. Here we demonstrate using the latter strategy the highest reported room-te…
The effective quasistatic conductivity of composite polymeric electrolytes is studied in terms of a hard-core--penetrable-layer model. Used to incorporate the interface phenomena (such as amorphization of the polymer matrix around filler particles, stiffening effect by those on the amorphous phase, irregularities of the filler grains' surfaces, etc.), the layers are assumed to be electrically inhomogeneous, consisting of a finite or infinite number of concentric uniform shells. The rules of dominance, imposed on the overlapping regions, are equivalent to the requirement that the local electric…
An all solid-state thin film lithium ion battery has been touted the holy grail for energy storage technology ever since the inception of the first one in 1986 by Keiichi Kanehori. Solid-state batteries provide the distinct advantage of outperforming current technology by having a simpler composition, being easier and cheaper to manufacture, safer and having a higher theoretical gravimetric and volumetric energy density. The commercialization of this technology however, is plagued by its own set of challenges, primarily low ionic conductivity and interfacial stability of the solid-state electr…
We have developed a technique to tune the carrier density in graphene using a lithium-ion-based solid electrolyte. We demonstrate that the solid electrolyte can be used as both a substrate to support graphene and a back gate.It can induce a change in the carrier density as large as 1*10^14/cm^2, which is much larger than that induced with oxide-film dielectrics, and it is comparable with that induced by liquid electrolytes. Gate modulation of the carrier density is still visible at 150 K, which is lower than the glass transition temperature of most liquid gating electrolytes.
Machine Learning Prediction Models for Solid Electrolytes based on Lattice Dynamics Properties
Kyungpook National University（庆北国立大学）；Sungkyunkwan University（成均馆大学）；Harvard University（哈佛大学）；Korea Research Institute of Chemical Technology（韩国化学技术研究院）
The field-dependent ion transport in thin samples of different glasses is characterised by means of nonlinear conductivity spectroscopy. AC electric fields with strengths up to 77 kV/cm are applied to the samples, and the Fourier components of the current spectra are analysed. In the dc conductivity regime and in the transition region to the dispersive conductivity, higher harmonics in the current spectra are detected, which provide information about higher--order conductivity coefficients. Our method ensures that these higher--order conductivity coefficients are exclusively governed by field-…
Recent experimental observations of anisotropic conductivity in stretched polymer electrolytes films of the polyethylene oxide family are discussed. The main experimental observations, enhancement of the ionic diffusion and conductivity in the stretch direction and decrease in these transport coefficients in the normal direction are interpreted in terms of an effective two-phase model. This two-phase model is based on the idea that a highly conducting phase is associated with oriented molecular structures which are surrounded by poorly conducting boundary regions. This model is evaluated withi…
Synergetic Enhancement on Bulk and Grain Boundary Ionic Conduction of Mg Doped High-Entropy NASICON-Type Solid Electrolyte for Solid-State Na+ Batteries by Spray Flame Synthesis
In this communication we report the fluorine ion dynamics in mixed alkali oxyfluro vanadate glasses. We have measured the electrical conductivity using impedance spectroscopy technique Room temperature conductivity falls to 5 orders of magnitude from its single alkali values at 33 mol% of rubidium concentration. We have also estimated the distance between similar mobile ions using the density values. Assuming this distance as the hopping distance between the similar ions we have estimated the anionic (Fluorine ion in our case) conductivity. It is observed that the fluorine ion dynamics mimics …
Present paper reports, the structural, microstructural, electrical, dielectric properties and ion dynamics of a sodium based solid polymer electrolyte films comprising of PEO8-NaPF6+ x wt. % SN. The structural and surface morphology properties have been investigated by XRD and FESEM. Different microscopic interaction among the polymer, salt and SN have been analyzed through FTIR. The dielectric permittivity and loss tangent enable us to estimate the dc conductivity, dielectric strength, double layer capacitance, and relaxation time. The loss tangent relaxation peak shifts towards high-frequenc…
Li-Ion Solid-State Electrolytes (Li-SSEs) are a promising solution that resolves the critical issues of conventional Li-Ion Batteries (LIBs) such as poor ionic conductivity, interfacial instability, and dendrites growth. In this study, a platform consisting of a high-throughput screening and a machine-learning surrogate model for discovering superionic Li-SSEs among 20,237 Li-containing materials is developed. For the training database, the ionic conductivity of Na SuperIonic CONductor (NASICON) and Li SuperIonic CONductor (LISICON) type SSEs are obtained from the previous literature. Then, th…
Solid-state electrolytes for Li-ion batteries are attracting growing interest as they allow building safer batteries, also using lithium metal anodes. Here we studied a compound in the lithium superionic conductor (LISICON) family, i.e. Li4-xGe1-xPxO4 (LGPO). Thin films were deposited via pulsed laser deposition and their electrical properties were compared with ceramic pellets. A detailed characterization of the micro structure shows that thin films can be deposited fully crystalline at higher temperatures but also partially amorphous at room temperature. The conductivity is not strongly infl…
