Electrolyte Materials For Lithium-ion Batteries Research Articles

Fabrication of single-ion conductive quasi-solid-state electrolyte membrane for high-performance lithium-ion batteries

The aim of this work is to develop new quasi-solid-state electrolyte materials for lithium-ion batteries (LIBs) to improve their safety and comprehensive electrochemical performance. Herein, helical mesoporous silica nanofibers were synthesized by a sol–gel method. After grafting lithium salt onto their surfaces, a single-ion conductor (SL) was obtained. Then, using poly(vinylidene fluoride-co-hexafluoropropylene) as the polymer matrix, SL as the filler, a porous composite film was prepared by solution casting method. After soaking organic electrolyte with low concentration Li salt till saturation, one quasi-solid-state electrolyte membrane (PSLE) was achieved. It showed high electrolyte adsorption rate of 660 % and good thermal stability. A high lithium-ion transfer number of 0.85 indicated typical single-ion conductivity. Moreover, a high electrochemical stability window of up to 5.5 V and an ionic conductivity of 2.5 × 10−3 S·cm−1 at 25 °C were gained. The assembled LFP|PSLE|Li battery exhibited excellent rate performance and cycle stability, indicating that the PSLE has great application prospect in solid-state LIBs.

Computational Design of Inorganic Solid-State Electrolyte Materials for Lithium-Ion Batteries

Computational Design of Inorganic Solid-State Electrolyte Materials for Lithium-Ion Batteries

Learning techniques for designing solid-state lithium-ion batteries with high thermomechanical stability

This work is an implication of machine learning (ML) techniques to predict thermomechanically compatible cathode and electrolyte materials for lithium-ion batteries (LIBs). The ML models were trained on a dataset of 5,578 materials, using the coefficient of thermal expansion (CTE) as the target property. The optimized extra trees model was first evaluated using 10-fold-cross-validation and then the model was further validated using an experimental dataset. Additionally, density function theory (DFT) calculations were performed on MgBe13 and MgPd2 in which the electron localization function (ELF) plots show an agreement between the predicted CTE and the overall type of bonding supported by the melting temperature being the most important feature in the model. After validation, the model was used to predict the CTE for 25 K materials. Based on the predictions, cathode and electrolyte materials were screened and analyzed for thermomechanical compatibility using CTE.

ConFlat cell foroperandoelectrochemical X-ray studies of lithium-ion battery materials in commercially relevant conditions

In situandoperandotechniques play an important role in modern battery materials research and development. As materials characterization and application requirements advance, so too must thein situ/operandotest methods and hardware. The effects of temperature, internal mechanical pressure and parasitic reactions due to, for example, cell sealing are critical for commercial scale-up but often overlooked inin situ/operandocell designs. An improved electrochemicaloperandocell for X-ray diffraction and spectroscopy using ConFlat-style flanges in combination with a beryllium window is presented. The cell is reusable and simple to fabricate and assemble, providing superior sealing, relevant and adjustable cell stack pressure, and reproducible charge/discharge cycling performance for short- and long-term experiments. Cell construction, electrochemical performance, and representativeoperandoX-ray powder diffraction measurements with carbon and aluminium electrodes at temperatures between 303 and 393 K are provided.Operandoelectrochemical cell testing at high temperatures allows access to temperature-sensitive phase transitions and opens the way for analysis and development of new lithium-based cathode, anode and electrolyte materials for lithium-ion batteries.

The Role of TiO2 Particles on the Ion Conduction Mechanism in Polyether Electrolyte Having Cyanoethoxy Sidechain

Although solid-state polymer electrolytes (SPE) have attracted much attention as a safe electrolyte material for lithium-ion batteries (LIB), one major limitation of SPE resides in the low ionic conductivity[1]. Previous study reported the improvement of ionic conductivity by adding inorganic particles into polymer electrolytes[2]. However, a molecular-level understanding of its effect on the Li+ conduction mechanism is still lacking.In this study, we select polyether having cyanoethoxy sidechain as a polymer matrix, and clarify the effect of TiO2 nanoparticles on the Li+ conduction mechanism. Differential scanning calorimetry and thermogravimetric analysis confirmed that glass transition temperature (T g) and the thermal stability of electrolytes were not affected by TiO2. On the other hand, electrolyte with TiO2 showed higher ionic conductivity than the electrolyte without TiO2. Various (electro)chemical and spectroscopic analyses were performed to clarify the key descriptor for the ionic conductivity. Infrared spectroscopy confirmed that the Li+–CN interaction was not affected by the existence of TiO2. However, it also suggested two types of the dissociated anion (free anion and anion interacting with the surface hydroxyl group on TiO2) in the electrolyte with TiO2. Based on these results, observed improvement of Li+ conduction for TiO2-contained electrolytes can be due to the trapping of bulky anion by surface hydroxyl groups on TiO2.In conclusion, we clarify that the anion trapping by the surface hydroxyl group on TiO2 nanoparticles could facilitate Li+ conduction, probably due to the absence of bulky anion, which sterically inhibits Li+ transportation. The surface hydroxyl groups on inorganic fillers thus play a vital role in facilitating Li+ conduction.[1] X. Zhigang et al., J. Matter. Chem. A, 2015, 3, 19218–19253.[2] F. Croce et al., Nature, 1998, 394, 456–458.

Anion Charge Dependent Lithium Ion Diffusion in Solids

Utilizing solid-state electrolyte materials for lithium-ion batteries not only fundamentally solve the safety problem of the commercial lithium-ion batteries, but also greatly increase the energy density of batteries. Lithium solid-state electrolyte materials should have high conductivities at room temperature comparable to liquid electrolyte, good (electro)chemical stabilities, mechanical properties, and excellent compatibilities with electrodes. The proposed design principles for lithium superionic conductors mainly include the concepts of bcc anion framework, low lithium phonon density center, and high distortion lithium-anion polyhedron. Moreover, the smaller anionic charge is well considered to benefit for the rapid transport of lithium ion, e.g. negative monovalent anions are more favorable for cation diffusion than negative divalent anions.However, our recent studies of the chalcopyrite-structured sulfides and non-spinel-structured halides show that the lithium-ion migration energy barrier can be effectively reduced by comprehensively regulating the anion charge and lithium-ion coordination environments. For example, for lithium ion diffusion between two adjacent lithium-anion octahedrons through a tetrahedral transition state, the greater the anionic charge is, the lower the lithium ion diffusion energy barrier will be. While for lithium ion diffusion between two adjacent lithium-anion tetrahedrons through an octahedral transition state, the smaller the anion charge is, the lower the lithium ion diffusion barrier will be. According to this design principle and choosing the appropriate cations to isolate the electronic conductive channels, we obtained the quaternary Li2CuPS4 solid electrolyte material with tetrahedral lithium occupations. Li2CuPS4 not only has high thermodynamic stability, but also theoretically possess the high ionic conductivity of 84.9 mS/cm at room temperature. In addition, the non-spinel halide Li3LaI6 with octahedral lithium occupations has relatively high ionic conductivity of 1.23 mS/cm at room temperature, and its thermodynamic stability and electrochemical stability are far superior to sulfides. This new understanding of comprehensively regulating the anion charge and lithium-ion coordination environments to enhance lithium ion transport can be applied for the design and optimization of new superionic conductors.

Two Players Make a Formidable Combination: In Situ Generated Poly(acrylic anhydride-2-methyl-acrylic acid-2-oxirane-ethyl ester-methyl methacrylate) Cross-Linking Gel Polymer Electrolyte toward 5 V High-Voltage Batteries.

Electrochemical performance of high-voltage lithium batteries with high energy density is limited because of the electrolyte instability and the electrode/electrolyte interfacial reactivity. Hence, a cross-linking polymer network of poly(acrylic anhydride-2-methyl-acrylic acid-2-oxirane-ethyl ester-methyl methacrylate) (PAMM)-based electrolyte was introduced via in situ polymerization inspired by "shuangjian hebi", which is a statement in a traditional Chinese Kungfu story similar to the synergetic effect of 1 + 1 > 2. A poly(acrylic anhydride) and poly(methyl methacrylate)-based system is very promising as electrolyte materials for lithium-ion batteries, in which the anhydride and acrylate groups can provide high voltage resistance and fast ionic conductivity, respectively. As a result, the cross-linking PAMM-based electrolyte possesses a significant comprehensive enhancement, including electrochemical stability window exceeding 5 V vs Li+/Li, an ionic conductivity of 6.79 × 10-4 S cm-1 at room temperature, high mechanical strength (27.5 MPa), good flame resistance, and excellent interface compatibility with Li metal. It is also demonstrated that this gel polymer electrolyte suppresses the negative effect resulting from dissolution of Mn2+ ions at 25 and 55 °C. Thus, the LiNi0.5Mn1.5O4/Li and LiNi0.5Mn1.5O4/Li4Ti5O12 cells using the optimized in situ polymerized cross-linking PAMM-based gel polymer electrolyte deliver stable charging/discharging profiles and excellent rate performance at room temperature and even at 55 °C. These findings suggest that the cross-linking PAMM is an intriguing candidate for 5 V class high-voltage gel polymer electrolyte toward high-energy lithium-on batteries.

Dielectric and impedance analysis of Li0.5La0.5Ti1-xZrxO3(x = 0.05 and 0.1) ceramics as improved electrolyte material for lithium-ion batteries

AbstractThe most attractive property of Li0.5La0.5TiO3 (LLTO) electrolytes is their high ionic conductivity. Studies have shown that LLTO is capable of existing in a state with an ionic conductivity of 10-3 S/cm, which is comparable to liquid electrolytes. In addition to the high ionic conductivity of the material, LLTO is electrochemically stable and able to withstand hundreds of cycles. So, the studies of the solid electrolyte material are very important for the development of lithium-ion batteries. In the present paper, Li0.5La0.5Ti1-xZrxO3 (x = 0.05 and 0.1) have been prepared by a solid-state reaction method at 1300 °C for 6 hours to improve electrolyte materials for lithium-ion batteries. The phase identified by X-ray diffractometry and crystal structure corresponds to pm3m (2 2 1) space group (Z = 1). The frequency and temperature dependence of impedance, dielectric permittivity, dielectric loss and electric modulus of the Li0.5La0.5Ti1-xZrxO3 (x = 0.05 and 0.1) have been investigated. The dielectric and impedance properties have been studied over a range of frequency (42 Hz to 5 MHz) and temperatures (30 °C to 100 °C). The frequency dependent plot of modulus shows that the conductivity relaxation is of non-Debye type.

Study of the temperature dependent transport properties in nanocrystalline lithium lanthanum titanate for lithium ion batteries

The nano-crystalline Li0.5La0.5TiO3 (LLTO) was prepared as an electrolyte material for lithium-ion batteries by the sol–gel method. The prepared LLTO material is characterized by structural, morphological and electrical characterizations. The LLTO shows the cubic perovskite structure with superlattice formation. The uniform distribution of LLTO particles has been analyzed by the SEM and TEM analysis of the sample. Impedance measurements at various temperatures were carried out and the temperature dependent conductivity of as prepared LLTO nanopowders at different temperatures from room temperature to 448K has been analyzed. The transport mechanism has been analyzed using the dielectric and modulus analysis of the sample. Maximum grain conductivity of the order of 10−3Scm−1 has been obtained for the sample at higher temperatures.

Investigations on pure and Ag doped lithium lanthanum titanate (LLTO) nanocrystalline ceramic electrolytes for rechargeable lithium-ion batteries

The nano-crystalline Li0.5La0.5TiO3 (LLTO) was prepared as an electrolyte material for lithium-ion batteries. The effect of Ag+ ion doping in three different concentrations were investigated: Ag0.1Li0.4La0.5TiO3, Ag0.3Li0.2La0.5TiO3, and Ag0.5La0.5TiO3 along with Li0.5La0.5TiO3. The prepared pure and Ag+ doped LLTO were subjected for structural, morphological, electrical and optical characterizations. The cubic superlattice structure of LLTO nano-powder was altered due to the Ag+ substitution tending towards a tetragonal phase. Increasing Ag+ substitution a complete tetragonal phase occurs in Ag0.5La0.5TiO3. The average particle size of the prepared ceramic electrolyte ranged between 80nm and 120nm. The photoluminescence study reveals that the LLTO and Ag doped LLTO gives a blue emission peak. The size effect on grain and grain boundary resistance was observed and reported. With Ag+ substitution, the conductivity got decreased due to the impedance caused by Ag+ ions in the conducting path of Li+ ion. Among all the samples, Ag0.5La0.5TiO3 shows maximum conductivity of the order of 10−3Scm−1.