Properties Of Li1 Research Articles

Effect of sintering temperature and holding time on structure and properties of Li1.5Ga0.5Ti1.5(PO4)3 electrolyte with fast ionic conductivity

Li1.5Ga0.5Ti1.5(PO4)3 (LGTP) is recognized as a promising solid electrolyte material for lithium ions. In this work, LGTP solid electrolyte materials were prepared under different process conditions to explore the effects of sintering temperature and holding time on relative density, phase composition, microstructure, bulk conductivity, and total conductivity. In the impedance test under frequency of 1−106 Hz, the bulk conductivity of the samples increased with increasing sintering temperature, and the total conductivity first increased and then decreased. SEM results showed that the average grain size in the ceramics was controlled by the sintering temperature, which increased from (0.54±0.01) μm to (1.21±0.01) μm when the temperature changed from 750 to 950 °C. The relative density of the ceramics increased and then decreased with increasing temperature as the porosity increased. The holding time had little effect on the grain size growth or sample density, but an extended holding time resulted in crack generation that served to reduce the conductivity of the solid electrolyte.

Influence of mixing technique on properties of Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte prepared by the solid-state reaction - A comparison of dry 3D mixing technique with wet ball-milling

Li1.3Al0.3Ti1.7(PO4)3 (LATP) NASICON(Na Super Ion Conductive)-type solid electrolyte is prepared using conventional wet ball-milling and dry 3D mixing techniques to investigate the influence of mixing technique on properties of LATP. The mixing techniques influence impurity formation of calcined LATP powder. Thus, sintering behavior of the calcined powders is also affected by the mixing technique, i.e. LiTiPO5 formation is confirmed in the ball-milling samples and Li-ion conductive Li4P2O7 is main impurity in the 3D mixing samples. The influence is not limited to impurity formation. Uniform grains are observed in the 3D mixing pellet, contrarily, non-uniform sintering occurs in the ball-milling sample. As a result, the 3D mixing pellets demonstrate higher Li-ion conductivity than the ball-mill samples. The dry 3D mixing technique, which can omit drying process, is promising for LATP preparation owing to simplification of preparation process and a formation of high Li-ion conductive LATP pellets. Also, this study clearly shows that the mixing techniques affect ionic conductivity of the sintered LATP significantly, emphasizing importance of mixing procedure in the solid-state reaction.

Synthesis, structural investigations and properties of Si-modified Li1.5Al0.5Ge1.5(PO4)3 glass-ceramics

The properties of the Li1.5Al0.5Ge1.5(PO4)3 glass-ceramics were modified by the partial substitution of P5+ by Si4+, and the synthesis process is optimized. The thermal behavior of the original Li1.5+хAl0.5Ge1.5SixP3-xO12 (0 ≤ x ≤ 0.5) glasses was investigated using differential scanning calorimetry (DSC), optical dilatometry and heating microscopy. The glass transition temperature (Tg) decreases from 525 to 457 °C with increasing additive content from x = 0 to x = 0.5. Single-phase glass-ceramics with the NASICON-type structure were synthesized up to x = 1, which was confirmed by X-ray diffraction (XRD), Raman and energy-dispersive X-ray (EDX) mapping data. It has been shown that the SiO2 addition has a beneficial effect on the electrical properties of glass-ceramics, crystallized at 700 and 750 °C. However, heat treatment at 820 °C leads to a smaller increase in conductivity. Therefore, Si-containing glass-ceramics should be produced at lower temperatures than pure LAGP, which is 750 °C and correlated with the thermal analysis results. The influence of the SiO2 addition on the bulk and grain boundary conductivity of the Li1.5Al0.5Ge1.5(PO4)3 has been studied in detail. The Li1.52Al0.5Ge1.5Si0.02P2.98O12 glass-ceramics has the highest total ionic conductivity of 4.55·10−4 S/cm at RT and negligible electronic conductivity of 7.5·10−10 S/cm, therefore can be considered as promising solid electrolytes for all-solid-state batteries.

Effect of impeller design on the properties of Li1.03Ni0.8Mn0.1Co0.1O2 cathode material synthesized via co-precipitation method

Li1.03Ni0.8Mn0.1Co0.1O2 (NMC811) is the most promising composition for lithium-ion battery cathodes due to its low cobalt content and high capacity. The most widely used method to synthesize NMC811 is co-precipitation. Even though the co-precipitation process requires great control over each parameter, research that sheds light on the effect of impeller types on the electrode material’s electrochemical performances is very limited. In this study, computational fluid dynamic (CFD) simulations for different types of impellers (pitched blade, hydrofoil blade, propeller, and Rushton turbine) were carried out using the Taguchi L4 array. The impellers were 3D printed, and the precursors (Ni0.8Mn0.1Co0.1(OH)2) were synthesized by utilizing those printed impellers. Simulations were used to gain insight into how impeller type affects the flow pattern, hence the final electrochemical performance of NMC811. The best cycle performance was obtained when a propeller-type impeller was used in coprecipitation. It delivered a discharge capacity of 174.58 mAh/g at a C/20 rate, with a coulombic efficiency of 96.02%. On the other hand, the Rushton turbine yielded the worst initial discharge capacity of 100.12 mAh/g at a C/20 rate. This significant difference proves that impeller geometry affecting the flow pattern strongly influences the electrochemical performance of the cathode.

Properties of Li1.3Al0.3Ti1.7(PO4)3 Lithium-Conducting Ceramics Synthesized by Spark Plasma Sintering

Properties of Li1.3Al0.3Ti1.7(PO4)3 Lithium-Conducting Ceramics Synthesized by Spark Plasma Sintering

Effects of B2O3 on crystallization kinetics, microstructure and properties of Li1.5Al0.5Ge1.5(PO4)3-based glass-ceramics

Lithium-ionic conductors of Li1+xAlxGe2-x(PO4)3 family are considered as one of the most attractive solid electrolytes. Li1.5Al0.5Ge1.5(PO4)3 composition obtained by glass-ceramic route exhibits the highest electrical conductivity at room temperature. The introduction of sintering additives makes it possible to modify the properties of solid electrolytes. Glass-ceramics of the Li1.5Al0.5Ge1.5(PO4)3–xB2O3 series (x = 0, 0.05, 0.1, 0.15, 0.2 wt%) was obtained by glass crystallization at optimal conditions of heat treatment. The influence of B2O3 additive on thermal stability and crystallization process of initial glasses was studied by DSC method. The phase composition, microstructure and transport properties of glass-ceramics were investigated by XRD, SEM and impedance spectroscopy, respectively. The structure of the glass-ceramics was characterized by Raman spectroscopy. Glass-ceramics was found to be single-phase (R-3c) when 0 ≤ x ≤ 0.15, but impurity phases Li4P2O7 and AlPO4 appear at x = 0.20. The conductivity of B2O3-added solid electrolytes is higher compared to the pristine Li1.5Al0.5Ge1.5(PO4)3. Its ionic conductivity reached 5.5 × 10−4 S cm−1 at 25 °C. The obtained glass-ceramic electrolytes are promising for use in all-solid-state lithium-ion batteries.

Effects of Non-Stoichiometry on the Ground State of the Frustrated System Li0.8Ni0.6Sb0.4O2.

The non-stoichiometric system Li0.8Ni0.6Sb0.4O2 is a Li-deficient derivative of the zigzag honeycomb antiferromagnet Li3Ni2SbO6. Structural and magnetic properties of Li0.8Ni0.6Sb0.4O2 were studied by means of X-ray diffraction, magnetic susceptibility, specific heat, and nuclear magnetic resonance measurements. Powder X-ray diffraction data shows the formation of a new phase, which is Sb-enriched and Li-deficient with respect to the structurally honeycomb-ordered Li3Ni2SbO6. This structural modification manifests in a drastic change of the magnetic properties in comparison to the stoichiometric partner. Bulk static (dc) magnetic susceptibility measurements show an overall antiferromagnetic interaction (Θ = −4 K) between Ni2+ spins (S = 1), while dynamic (ac) susceptibility reveals a transition into a spin glass state at a freezing temperature TSG ~ 8 K. These results were supported by the absence of the λ-anomaly in the specific heat Cp(T) down to 2 K. Moreover, combination of the bulk static susceptibility, heat capacity and 7Li NMR studies indicates a complicated temperature transformation of the magnetic system. We observe a development of a cluster spin glass, where the Ising-like Ni2+ magnetic moments demonstrate a 2D correlated slow short-range dynamics already at 12 K, whereas the formation of 3D short range static ordered clusters occurs far below the spin-glass freezing temperature at T ~ 4 K as it can be seen from the 7Li NMR spectrum.

Effective Repeatable Mechanoluminescence in Heterostructured Li1- x Nax NbO3 : Pr3.

Mechanoluminescence (ML) is a striking optical phenomenon that is achieved through mechanical to optical energy conversion. Here, a series of Li1 -x Nax NbO3 : Pr3+ (x= 0, 0.2, 0.5, 0.8, 1.0) ML materials have been developed. In particular, due to the formation of heterostructure, the synthesized Li0.5 Na0.5 NbO3 : Pr3+ effectively couples the trap structures and piezoelectric property to realize the highly repeatable ML performance without traditional preirradiation process. Furthermore, the ML performances measured under sunlight irradiation and preheating confirm that the ML properties of Li0.5 Na0.5 NbO3 : Pr3+ can be ascribed to the dual modes of luminescence mechanism, including both trap-controllable and self-recoverable modes. In addition, DFT calculations further confirm that the doping of Na+ ions in LiNbO3 leads to electronic modulations by the formation of the heterostructures, which optimizes the trap distributions and concentrations. These modulations improve the electron transfer efficiency to promote ML performances. This work has supplied significant references for future design and synthesis of efficient ML materials for broad applications.

Effects of lithium source and electrochemical window on the properties of Li1.2Fe0.16Ni0.24Mn0.4O2 cathode material prepared by oxalate co-precipitation method

Effects of lithium source and electrochemical window on the properties of Li1.2Fe0.16Ni0.24Mn0.4O2 cathode material prepared by oxalate co-precipitation method

Superior electrochemical properties of Zirconium and Fluorine co‐doped Li1.20[Mn0.54Ni0.13Co0.13]O2 as cathode material for lithium ion batteries

In the paper, the Zr4+ and F− co-doping was employed to expectedly improve the rate performance and structure stability of Li1.20[Mn0.54Ni0.13Co0.13]O2. The effects of Zr4+ doping and F− doping on the micro-structure, cathode morphology and element chemical state were investigated by XRD, Rietveld refined XRD, SEM, TEM, and XPS. It indicated the Zr4+ and F− were inserted into the cathode crystal structure with ideally designed. Besides, the electrochemical characterization confirmed that the cathode after the Zr4+ or/and F− doping delivered the superior electrochemical properties when compared to the pristine one. Firstly, the Li1.20[Mn0.52Ni0.13Co0.13Zr0.02]O1.95F0.05 could express a high discharge capacity of 132.6 mAhg−1 at 5C rate, which was 40.1 mAhg−1 larger than that of the pristine one (92.5 mAhg−1). In addition, the Li1.20[Mn0.52Ni0.13Co0.13Zr0.02]O1.95F0.05 remained a capacity retention of 90.7% after 100 cycles at 2C rate and with the 148.2 mAh g−1 left. While the bare cathode delivered an initial discharge capacity of 134.1 mAhg−1 at 2C rate, then dramatically attenuated to 108.7 mAhg−1 after 100 cycles with the capacity retention of 81.1%. The enhanced electrochemical properties of Li1.20[Mn0.52Ni0.13Co0.13Zr0.02]O1.95F0.05 was mainly put down to the suppression of charge transfer resistance increase by the Zr4+ and F− doping modification along with cycles.

Effect of Na Doping on Electrochemical Properties of Cobalt-Free Li-Rich Mn-Based Cathode Materials

Na doping is introduced to improve the electrochemical properties of Li1.2Mn0.6Ni0.2O2 cathode material, which is synthesized by sol–gel method. The effect of Na doping on the morphological, structural and electrochemical properties was systematically studied and analyzed. These results illustrate that lattice layer spacing is enlarged by Na doping, which is beneficial for the diffusion of Li-ion, and the voltage fading is successfully suppressed. The best electrochemical properties were obtained when Na doping amount is approximately 1%, which is attributed to the stronger structural stability and better reversibility of Li+ during the initial charge and discharge process.

The mechanism of enhanced ionic conductivity in Li1.3Al0.3Ti1.7(PO4)3–(0.75Li2O·0.25B2O3) composites

Abstract The oxide-based Li+ conductors are considered as potential solid electrolytes for lithium-ion batteries. Among the NASICON–type materials, Li1.3Al0.3Ti1.7(PO4)3 (LATP) seems to be a promising candidate for application. Although its bulk conductivity is of the order of 10−3 S · cm−1, and seems to be sufficient for practical use, the total conductivity is considerably limited by the highly resistant grain boundaries. This shortcoming may be overcome by the formation of LATP–based ceramics with appropriate sintering aids. In this study, the 0.75Li2O·0.25B2O3 (LBO) glass with low melting point was chosen to improve the ionic conductivity of LATP. The properties of Li1.3Al0.3Ti1.7(PO4)3–y (0.75Li2O·0.25B2O3) (0 ≤ y ≤ 0.3) system were studied by means of: high temperature X-ray diffractometry (HTXRD), 6Li/7Li, 11B, 27Al and 31P magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR), thermogravimetry (TG), scanning electron microscopy (SEM), impedance spectroscopy (IS) and density methods. Based on the experimental results, it is shown that the use of LBO glass as a sintering aid results in the enhancement of the total ionic conductivity of LATP ceramics. The correlations between apparent density, microstructure, composition, sintering temperature and ionic conductivity are presented and discussed. The presumed mechanism of the conductivity enhancement is analyzed in terms of the brick-layer model (BLM). The highest value of the total ionic conductivity, equal to 1.9 × 10−4 S · cm−1, was obtained for LATP–0.1LBO sintered at 800 °C.

Impact of Li2.9B0.9S0.1O3.1 glass additive on the structure and electrical properties of the LATP-based ceramics

The existing solid electrolytes for lithium ion batteries suffer from low total ionic conductivity, which restricts its usefulness for the lithium-ion battery technology. Among them, the NASICON-based materials, such as Li1.3Al0.3Ti1.7(PO4)3 (LATP) exhibit low total ionic conductivity due to highly resistant grain boundary phase. One of the possible approaches to efficiently enhance their total ionic conductivity is the formation of a composite material. Herein, the Li2.9B0.9S0.1O3.1 glass, called LBSO hereafter, was chosen as an additive material to improve the ionic properties of the ceramic Li1.3Al0.3Ti1.7(PO4)3 base material. The properties of this Li1.3Al0.3Ti1.7(PO4)3–xLi2.9B0.9S0.1O3.1 (0 ≤ x ≤ 0.3) system have been studied by means of high temperature X-ray diffractometry (HTXRD), 7Li, 11B, 27Al and 31P magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR), thermogravimetry (TG), scanning electron microscopy (SEM), impedance spectroscopy (IS) and density methods. We show here that the introduction of the foreign LBSO phase enhances their electric properties. This study reveals several interesting correlations between the apparent density, the microstructure, the composition, the sintering temperature and the ionic conductivity. Moreover, the electrical properties of the composites will be discussed in the terms of the brick-layer model (BLM). The highest value of σtot = 1.5 × 10−4 S cm−1 has been obtained for LATP–0.1LBSO material sintered at 800 °C.

Effects of B2O3–Li2CO3–SiO2–ZnO glass on properties of Li0.43Zn0.27Ti0.13Fe2.17O4 ferrites sintered at low temperatures

In this study, B2O3–Li2CO3–SiO2–ZnO (BLSZ) glass was fabricated and employed as a sintering aid for Li0.43Zn0.27Ti0.13Fe2.17O4 ferrites. The introduction of BLSZ glass could allow the ferrites to be sintered at low temperatures (~920 °C) while maintaining a pure spinel phase. The results obtained from scanning electron microscopy revealed that BLSZ glass significantly promoted grain growth because of the liquid phase formed during sintering, which resulted in a homogeneous morphology with high densification. The saturation induction and saturation magnetization reached maximum values of 286.7 mT and 78.7 emu/g, respectively, with the addition of an appropriate amount (1.5 wt %) of BLSZ glass. This result can be attributed to the larger grains that were formed with the assistance of the BLSZ glass. Correspondingly, the coercivity and ferromagnetic resonance linewidth reached minimum values of 247.9 A/m and 236.6 Oe, respectively. The main reasons explaining this result are considered to be the homogeneous morphology and the low porosity of the samples. Therefore, it is believed that BLSZ glass can enable co-firing between LiZn ferrites and silver electrodes, which is crucial for the realization of low temperature co-fired ceramic (LTCC) technology.

Effect of Li salts on the properties of Li1.5Al0.5Ti1.5(PO4)3 solid electrolytes prepared by the co-precipitation method

ABSTRACTIn this study, Li1.5Al0.5Ti1.5(PO4)3 (LATP) solid electrolyte is prepared through co-precipitation using Li3PO4 and Li2C2O4 salts. The co-precipitates are heated at 800°C to obtain precursor powders. The precursor powders are then ball-milled to reduce the particle size to prepare dense LATP pellets. Li salts significantly influence the morphology and crystallinity of the precursor powders. The precursor powder prepared from Li3PO4 possesses a smaller particle size and lower crystallinity of LATP compared with Li2C2O4. The soft, low-crystallinity powder from Li3PO4 is easily crushed by the ball-milling. The average particle size is reduced to 30 nm, while the average size of particles from Li2C2O4 is 120 nm after the ball-milling. The small particle size promotes sintering of LATP pellets. As a result, LATP pellets prepared from Li3PO4 show higher Li ion conductivity than those from Li2C2O4 due to their high sinterability and large grain size (low grain-boundary resistance). The Li ion conductivity is 2.0 × 10−4 S cm−1 after sintering at 1050°C for 6 h. It is concluded that the Li source used to form the co-precipitate greatly influences the properties of sintered LATP pellet. The Li source is one key to obtain LATP with high Li ion conductivity.

Phase States and Dielectric Properties of Li0.17Na0.83NbуТа1 –уO3 Ceramic Solid Solutions Prepared by High-Pressure, High-Temperature Synthesis

The electrical properties and phase states of Li0.17Na0.83NbуТа1 –уO3 (y = 0.1–0.5) ferroelectric perovskite solid solutions prepared by high-pressure, high-temperature synthesis have been studied using impedance spectroscopy. The e'(T) and σsv(T) curves of the solid solutions have been shown to have anomalies due to phase transitions of the materials. Their Curie temperature has been found to decrease with increasing Ta concentration. The static electrical conductivity of the solid solutions has been measured as a function of temperature and the enthalpies of activation of charge carriers in them have been evaluated. The Li0.17Na0.83Nb0.1Та0.9O3 solid solution has been shown to be a high-temperature superionic conductor. Possible mechanisms of the observed phenomena are discussed.

Surface modification of Li1.20Mn0.54Ni0.13Co0.13O2 cathode materials with SmF3 and the improved electrochemical properties

The Li1.20Mn0.54Ni0.13Co0.13O2 cathode materials with the different SmF3 coating contents were successfully synthesized through the typical wet chemical method. The X-ray diffractometer, scanning electron microscopy, transmission electron microscope, X-ray photoelectron spectroscopy and galvanostatic charge–discharge tests were adopted to investigate the influence of SmF3 layer on the crystal structural, morphology and electrochemical properties of Li1.20Mn0.54Ni0.13Co0.13O2. The results showed that the cathode materials were successfully coated with SmF3 without changing its micro-structure. Besides, the electrochemical tests results demonstrated that electrochemical properties of Li1.20Mn0.54Ni0.13Co0.13O2 were significantly enhanced after applying the SmF3 coating. The specific discharge capacity of the 2 wt% SmF3 coated Li1.20Mn0.54Ni0.13Co0.13O2 is 30.4 mAh g−1 higher than that of pristine one at 0.5C rate. Meanwhile, the 2 wt% SmF3 coated Li1.20Mn0.54Ni0.13Co0.13O2 delivered an outstanding cycle stability with a high capacity retention of 91.4% after 100 cycles, while the pristine one showed the less discharge capacity and a low capacity retention of 85.2%. The enhanced electrochemical properties could be ascribed to the SmF3 coating layer, which not only stabilizes the cathode structure by restricting the side reaction between cathodes materials with electrolyte, but also relieves the increase of impedance for Li+ migration across the electrode/electrolyte interface during cycling.

Study of structural, dielectric and magnetic properties of Li0.5+0.5xFe2.5–1.5xPbxO4 ferrite nano-crystals synthesized by citrate gel method

The effect of Pb substitution on the structure, dielectric, impedance and magnetic properties of Li0.5+0.5xFe2.5–1.5xPbxO4 ferrite nano-crystals prepared by citrate gel method has been investigated. X-ray diffraction analysis confirmed the formation of cubic spinel phase and broadness of reflection peaks indicates the formation of smaller sized crystallites. The average crystallite size was observed to increase from 21.3 to 26.1 nm on increasing Pb substitution in Li0.5+0.5xFe2.5–1.5xPbxO4 ferrite. The surface analysis of the samples was performed using scanning electron microscopy. An improvement in the microstructure has been obtained on Pb doping. Dielectric and impedance measurements were carried out in the frequency range of 100 Hz–10 MHz. The dielectric properties of Li0.5+0.5xFe2.5–1.5xPbxO4 ferrite samples were improved much by the substitution of Pb ions. The low dielectric loss at higher frequencies identifies the potential of these ferrites for high frequency applications. Interestingly, a very large value for dielectric constant of the order of 107 has been obtained on Pb doping. The impedance spectroscopy technique was used to study the effect of grain and grain boundary on the electrical properties of the material. From the present investigation on Li0.5+0.5xFe2.5–1.5xPbxO4 ferrite, one can conclude that the substitution of Pb4+ ions play an important role to modify the magnetic and electrical properties of lithium ferrite desired for microwave devices and power applications.

Studies on structural and dielectric properties of Li0.5Fe2.5O4 doped in BaTi0.9Zr0.1O3 at higher frequency region

The BaTi0.9Zr0.1O3 (BTZr) substituted with Li0.5Fe2.5O4 (LF) having chemical formulae (1−x)BTZr + (x)LF at x = 0; x = 0.05; x = 0.10; and x = 0.15 was prepared using conventional solid-state reaction method. The grown composites were characterized by XRD, SEM with E-DAX, dielectric studies, impedance studies and conductivity studies. The XRD peaks are well indexed to the crystal planes for tetragonal perovskite and spinel ferrite. SEM microstructural analysis confirms the increase of grain size with lithium ferrite. Electrical properties such as dielectric constant, dielectric loss, impedance (Z′) and conductivity with variation of frequency range over 1 MHz–3.2 GHz at temperature 30 °C were measured and understood based on available models. The variations of dielectric constant and dielectric loss with varying temperature up to 500 °C at fixed frequencies 100 kHz and 1 MHz were also investigated. The value of dielectric constant is obtained more for high % LF in composites. Ferrite substitution improves the conductivity nature of the composite samples and can be attributed to higher grain size.

Influence of lithium content on the structural and electrochemical properties of Li1.20+x Mn0.54Ni0.13Co0.13O2 cathode materials for Li-ion batteries

The Li1.20+x Mn0.54Ni0.13Co0.13O2 (x = 0, 0.05, 0.10) cathode materials were synthesized via using co-precipitation method to obtain the [Mn0.54Ni0.13Co0.13](CO3)0.80 precursors and followed by 950 °C calcination process with different contents of LiOH·H2O. The morphology, micro-structural, and electrochemical properties of Li1.20+x Mn0.54Ni0.13Co0.13O2 (x = 0, 0.05, 0.10) cathode materials have been discussed by XRD, SEM and galvanostatic discharge–charge tests. All samples demonstrated the similar sphere-like secondary particles with an average diameter of 2–4 μm. The XRD results indicated that the proper excess Li+ could contribute to reducing the cation mixing degree between Li+ and Ni2+. When x = 0.05, the cathode demonstrated the optimal electrochemical properties with the initial discharge capacity of 278.5 mAh g−1, the capacity retention of 92.1% (194.7 mAh g−1) after 100 cycles and the discharge capacity of 104.5 mAh g−1 at 5 C rate.