Effect Of Lithium Content Research Articles

Effects of lithium content on the electrochemical performance of Li1+xV3O8 cathode materials for lithium-ion batteries

Lithium trivanadate (LiV3O8) is of great interest due to its large capacity, low cost and easy preparation. However, it still suffers from an inferior cyclability and rate capability. To solve these shortcomings of LiV3O8, a small extra amount of lithium was introduced into Li sites of LiV3O8. Herein, Li-doped LiV3O8 (Li1+xV3O8) materials were prepared and the electrochemical performance of Li1+xV3O8 changes with x from 0 to 0.1, 0.2 and 0.3. The discharge capacity of Li1+xV3O8 increases from x = 0 to 0.2 and then decreases, and the change trend of cycle performance is the same as that of discharge capacity. The optimal Li-doped LiV3O8 sample, Li1.2V3O8, exhibits much higher capacity and better cyclability and rate capability than LiV3O8. Galvanostatically discharged and charged between 2.0 and 4.0 V, Li1.2V3O8 and LiV3O8 present the initial discharge capacities of 305 and 268 mAh g−1 at 0.1 C (30 mA g−1), respectively, and the corresponding capacity retentions are 87% and 80% after 50 cycles. Even at a high current rate of 2 C, Li1.2V3O8 exhibits high discharge capacity of 173 mAh g−1, much higher than the discharge capacity of 133.6 mAh g−1 for LiV3O8. The better electrochemical performance of Li1.2V3O8 can be ascribed to the doping of appropriate amount of Li+ in LiV3O8 and the resulted higher diffusion coefficients of Li+ in Li1.2V3O8.

Structural analysis of non-stoichiometric lithium cuprates, Li2+2xCu1-2xO2-x. Effects of lithium content and thermal treatments

Lithium cuprate (Li2CuO2) is being used for a wide range of applications due to its high lithium diffusion through the layer structure. Moreover, Li2+2xCu1-xO2-x non-stoichiometric material shows enhanced physicochemical properties. Therefore, lithium location understanding is highly important for lithium cuprate applications. This paper reports the structural coherence analysis, local and long atomic arrangement of Li2+2xCu1-xO2-x using X-ray diffraction (XRD), pair distribution function (PDF) and solid-state nuclear magnetic resonance (NMR) techniques. Li2CuO2, containing different excess quantities of lithium (from 0 to 60 at%), were synthesized by solid-state reaction. The synthesized ceramics presented nonstoichiometric structures, with Li2CuO2 type-structure. Two structural models were proposed to explain the high enhancement physicochemical properties of these ceramics; (i) the extra lithium atoms substitute copper sites, and (ii) lithium species occupy interstitial sites in the crystalline structure. Additionally, further thermal treatments rearrange the non-stoichiometric crystalline structures into the stable Li2CuO2 phase.

Effects of Lithium Source and Content on the Properties of Li-Rich Layered Oxide Cathode Materials

Lithium-rich layered oxide (LLO) are considered high-capacity cathode materials for next-generation lithium-ion batteries. In this study, LLO cathode materials were synthesized via the hydroxide coprecipitation method followed by a two-step lithiation process using different lithium contents and lithium sources. The effects of lithium content and lithium source on structure and electrochemical performance were investigated. This study demonstrated the clear impact of Li/TM ratio on electrochemical performance. Lower Li/TM ratio reduced the irreversible capacity loss in the first cycle and provided better cycling stability among all samples. The best results exhibited an initial discharge capacity of 279.65 mAh g−1 and reached a discharge capacity of 231.9 mAh g−1 (82.9% capacity retention) after 30 cycles. The sample using Li2CO3 as lithium source exhibits better electrochemical performance than the sample using LiOH as lithium source. Therefore, it is important to choose the appropriate lithium source and optimal lithium content for improving structural properties and electrochemical performance of LLO.

Sol-gel synthesis and structural study of a lithium titanate phase Li 3xLa 2/3.x □1/3-2x TiO3 as solid electrolyte

Perovskite lithium lanthanum titanate (LLTO) was prepared as an inorganic solid electrolyte material for lithium ion batteries applications using sol-gel method. Three different compositions of : (a) 3x=0.3 (Li 0.3La 0.57TiO3), (b) 3x=0.5 (Li 0.5La 0.5TiO3) were prepared and calcined at 1000°C for 6h, and (c) 3x=0.1 (Li 0.1La 0.63TiO3) prepared and calcined at 1100°C for 6h. The effects of lithium content and calcination temperature on the structure of the perovskite powders were studied. The synthesized powders were characterized by X-ray diffraction analysis. Results indicate that the Li 0.3La 0.57TiO3 was crystallized in tetragonal structure of space group P4/mmm. On the other hand, Rietveld refinement analysis for the LLTO samples confirmed the formation of the Li 0.3La 0.57TiO3 crystalline phase in the tetragonal P4/mmm space group, the Li 0.5La 0.5TiO3 phase in the tetragonal P4/mmm space group, and Li 0.1La 0.63TiO3 phase in orthorhombic Pmmm space group.

Effect of lithium content on the mechanical and corrosion behaviors of HCP binary Mg–Li alloys

The microstructure, crystallographic texture, mechanical properties and corrosion resistance of as-extruded HCP Mg-xLi (x = 1, 3, 5; in wt%) alloys were investigated. The results indicated that the HCP Mg-5Li alloy with high lithium content exhibited a low degree of dynamic recrystallization (DRX) compared with Mg-1Li and Mg-3Li alloys. Besides, the 45° base (0001) texture of Mg-1Li alloy could turn into (11–20) and (10–10) prismatic texture of Mg-3Li and Mg-5Li alloys with c-axis approximately parallel to transverse direction (TD). As a result, the strong prismatic texture resulted in the mechanical anisotropy of as-extruded Mg-3Li and Mg-5Li alloys with higher mechanical strength and low elongation along extrusion direction (ED) (reverse for TD sample). Regarding of corrosion behaviors, filiform corrosion occurred in the three Mg–Li alloys, whilst the high lithium content could mitigate the groove-like corrosion and improve the corrosion resistance of Mg-5Li alloy, which was ascribed to the refined grains, prismatic texture and surface film.

Effect of Lithium on the Mechanical Behavior of Magnesium

Abstract Lithium is the metal with lowest density. Lithium addition to the magnesium results in an ultra-light weight alloy with excellent properties on a mass basis. In this work, the effect of lithium content on mechanical properties of magnesium were studied. Vacuum stir casting method was employed to cast the alloys. The extrusion of these binary alloys was carried out. Microstructures of all alloys were taken. Tensile tests of extruded alloys were conducted and property values were noted. Micro hardness test was conducted on both cast and extruded alloys.

Effects of Lithium Content on Structure and Electrochemical Properties of Li-rich Cathode Material Li1.2+xMn0.54Ni0.13Co0.13O2

Effects of Lithium Content on Structure and Electrochemical Properties of Li-rich Cathode Material Li1.2+xMn0.54Ni0.13Co0.13O2

Structural, morphological, optical and photodetector properties of sprayed Li-doped ZnO thin films

Lithium-doped zinc oxide thin films (ZnO:Li) at different percentages (0–4%) were deposited on glass substrates at 460 °C using the spray pyrolysis technique. The effect of lithium content on the structural, morphological and optical properties of ZnO:Li thin films was investigated. First, X-ray diffraction study revealed that undoped and Li-doped ZnO thin films crystallize in hexagonal wurtzite structure with a preferred orientation of the crystallites along (002) direction. The scanning electron microscopy (SEM) showed a clear hexagonal-shaped granular onto the surface of such films. Indeed, the averaged grain size, visualized by SEM, varied from 100 nm, for undoped ZnO, to 200 nm for ZnO:Li 4%. Second, the optical analysis by means of the transmittance and the reflectance measurements revealed that in UV–Vis domain, the average transmittance of the ZnO:Li thin films was 75%, while the average reflectance was <35% in the visible range. Moreover, the band gap energy, E g, decreased from 3.285 to 3.264 eV as Li content increases. On the other hand, the photoluminescence spectra revealed emission with multiple peaks and exhibited especially two emission bands in UV and visible regions. Finally, the ZnO photodetectors showed superior performance in the view of photocurrent.

The Effect of Lithium Content and Core to Shell Ratio on Structure and Electrochemical Performance of Core-Shell Li(1+x)[Ni0.6Mn0.4](1−x)O2 Li(1+y)[Ni0.2Mn0.8](1−y)O2 Positive Electrode Materials

Core-shell positive electrode materials with a core:shell mass ratio of 2:1 and 4:1 were synthesized in a two-step reaction. Powder X-ray diffraction, SEM and spatial EDS measurements were used to characterize the core and shell phases in the precursors and lithiated products. It was determined using EDS that the precursor and lithiated products are both core-shell and the two phases can be easily resolved with laboratory grade XRD equipment. Two phase Rietveld refinement was completed on the core-shell lithiated products. The results of these refinements in conjunction with contour plots of the lattice parameters within the Li-Ni-Mn oxide layered single phase region were used to position the core and shell of each sample on the Li-Ni-Mn-O phase diagram as a function of the amount of Li2CO3 used in synthesis. The shell phase retained an approximately fixed amount of Li while the Li content of the core phase increased as the overall Li content of the core-shell sample increased. Both the core and shell were electrochemically active. A specific capacity of 220 mAh/g was achieved in a core shell material between 2.5-4.6 V vs. Li/Li+.

Effect of Lithium Content on LiMnPO4 and Its Electrochemical Property for Lithium Ion Batteries

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Effects of Lithium Content and Surface Area on the Electrochemical Performance of Li1.2Mn0.54Ni0.13Co0.13O2

Lithium-rich, layered composites of xLi2MnO3•(1-x)LiNi1/3Mn1/3Co1/3O2 have been extensively studied for PHEVs and EVs. To ensure complete lithiation, most synthesis methods require the addition of excess lithium compared to the stoichiometric composition. In this study lithium enriched, layered composites of Li1.2Mn0.54Ni0.13Co0.13O2 were synthesized in a spray pyrolysis process. Spray pyrolysis allows for excellent control of composition and in this work the lithium content was systematically varied between 3.3 wt% excess and 3.3 wt% deficient compared to Li1.2Mn0.54Ni0.13Co0.13O2. The as-synthesized powders were annealed at 900°C for 2, 5 and 20 hours. Results indicate that as the annealing time is increased the surface areas is reduced from 9 to ∼2 m2 g−1. No new phases form during the annealing process although changes in the relative intensity of the (018) and (110) peaks imply a reorganization between the transition metal and lithium layers. An excess Li of 3.3 wt% is sufficient to counter these structural rearrangements and maintain discharge capacities close to 200 mAhg−1 after 100 cycles at C/3. Samples with a smaller surface area do not lead to improved capacity retention. The results also suggest that the Li2MnO3 structural component has a key role in the voltage fade for these materials.

Synthesis and electrochemical performance of Li1+xNi0.5Mn0.3Co0.2O2+δ (0 ≤ x ≤ 0.15) cathode materials for lithium-ion batteries

In this work, layered lithium-excess materials Li1+xNi0.5Mn0.3Co0.2O2+δ (x=0, 0.05, 0.10 and 0.15), of spherical morphology with primary nanoparticles assembled in secondary microspheres, were synthesized by a coprecipitation method. The effects of lithium content on the structure and electrochemical performance of these materials were evaluated by employing X-ray diffraction (XRD), inductive coupled plasma (ICP), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge tests. It is found that Li1.10Ni0.5Mn0.3Co0.2O2+δ, i.e., Li[(Ni0.5Mn0.3Co0.2)0.95Li0.05]O2 showed the best electrochemical performance due to the highly ordered layered structure, reduced cation mixing and the lowest charge transfer resistance. Li1.10Ni0.5Mn0.3Co0.2O2+δ delivered a discharge capacity of 145mAhg−1 at 125mAg−1 in the cut-off voltage of 2.5–4.3V, and had a capacity retention of 100% after 50 cycles at room temperature.

Effect of lithium content on the electrochemical properties of solid-state-synthesized spinel Li xMn 2O 4

Abstract Lithium-substituted Li xMn 2O 4 ( x = 0.98, 1.03, 1.08) spinel samples were synthesized by solid-state reaction. X-ray diffraction (XRD) patterns show that the prepared samples have a spinel structure with a space group of Fd 3 m. The cubic lattice parameter was determined from least-squares fitting of the XRD data. Li 1.03Mn 2O 4 shows high capacity at both low and high current densities, while Li 1.08Mn 2O 4 shows good cycling performance but relatively low capacity when cycled at both room and elevated temperatures. A variety of electrochemical methods were employed to investigate the electrochemical properties of these series of spinel Li xMn 2O 4.

The Effects of Lithium Content on the Structure and Electrochemical Properties of Li1+x(Mn0.5Ni0.5)1-xO2

not Available.

Effect on quench rate on the precipitation hardening of Al100-x Lix binary alloys

The quench sensitivity and the effect of lithium content on the precipitation hardening of Al-x at% Li (x = 0.5, 1, 2, 3, 6, and 8) alloys have been investigated by microhardness tests, scanning electron microscopy (SEM),and x-ray diffraction. In addition, the grain-size dependence on lithium concentration has been studied. The results showed that: (i) alloys with less than 6 at% Li are insensitive to quench rate, whereas alloys containing 6 at% Li or more are, to some extent, quench sensitive; (ii) the microhardness increases with increasing lithium content; (iii) SEM results show that the grain size diminishes with increasing lithium concentration both in naturally and in artificially aged specimens, the grain size in artificially aged specimens being greater than that in naturally aged specimens; (iv) the coexistence of δ' and δ phases suggests that small amounts of the δ phase could be precipitated at the expense of the δ' phase via partial dissolution.

Low cycle fatigue resistance of Al–Li alloys

Low cycle fatigue (LCF) resistance data from binary Al–Li, ternary Al–Li–Cu, and quaternary Al–Li–Cu–Mg alloys have been compiled and discussed. The LCF resistance is measured in terms of the variation of the number of reversals to failure 2Nfwith the plastic strain amplitude Δɛp /2 as well as a modified average plastic strain energy per cycle (ΔWp )modified , obtained at different applied total strain amplitudes (Δɛt /2). The data show the effects of microstructural features, namely dominant strengthening precipitates and the degree of recrystallisation as well as crystallographic texture. Lithium content, when in excess of 2·5 wt-%in aluminium decreases the low cycle fatigue resistance the most. The degree of aging, the degree of recrystallisation, and the degree of texture also influence the LCF resistance; among which the effect of the degree of aging is the most pronounced. The effects of lithium content in aluminium solid solution and strengthening precipitates obtainable by the change in the Li/Cu ratio are found to be marginal. Based on a modified total cyclic plastic strain energy till fracture, it is shown that most of the Al–Li alloys exhibit degradation in their LCF resistance in both hypotransition (higher fatigue lives) and hypertransition (lower fatigue lives) regions. Such degradation is attributed to the combined effects of mechanical fatigue, strain localisation through dislocation–precipitate interaction, environmental effects, and finally strain localisation through the high angle grain boundaries. In comparison with the currently used 2XXX and 7XXX series aluminium alloys, Al–Li alloys require substantial improvement before they can be considered for fatigue critical applications.

Effects of lithium content on the electrochemical lithium intercalation reaction into LiNiO 2 and LiCoO 2 electrodes

The electrochemical lithium intercalation reaction into LiNiO 2 and LiCoO 2 electrodes in 1 M LiClO 4—propylene carbonate solution is investigated as a function of lithium content in the oxide electrodes by using X-ray diffractometry (XRD), electrochemical impedance spectroscopy (EIS), and a galvanostatic intermittent titration technique (GITT). Li 1-δNiO 2 shows a greater loss in capacity during the first intermittent discharge, as well as a higher resistance for the electrochemical intercalation reaction, in comparison with Li 1-δCoO 2. This is attributed to a partial cation mixing in Li 1-δNiO 2 which is substantiated by XRD studies. The electrochemical impedance spectra of the Li 1-δNiO 2 electrode reveals that the magnitude of the intermediate frequency arc that is associated with the absorption reaction decreases with increasing lithium content, (1 — δ), in the range from 0.5 to 0.7. By contrast, Li 1-δCoO 2 exhibits the reverse behaviour.—The component diffusivities of lithium ions display a nearly constant value, in the order of 10 −11 cm 2 s −1, for both electrodes at room temperature, irrespective of the value of (1 — δ) over the range 0.5–0.7. It is suggested that lithium-ion diffusion through both the layered oxides is affected by the number of empty sites within the lithium-ion layer, and not by the lattice parameter.

Effects of lithium content on the electrochemical lithium intercalation reaction into LiNiO2 and LiCoO2 electrodes

Effects of lithium content on the electrochemical lithium intercalation reaction into LiNiO2 and LiCoO2 electrodes

Ageing behaviour and toughness of silicon carbide particulate reinforced Al-Li-Cu-Mg-Zr metal matrix composites

The effects of lithium content on the ageing characteristic and notched tensile properties of particulate reinforced Al-Li-Cu-Mg-Zr based metal matrix composites (MMCs) have been investigated. MMC sheet containing 20 wt% silicon carbide particulate produced by a conventional powder metallurgy route aged at a similar rate as unreinforced sheet, and the highest strengths were achieved in samples containing 2–2.5 wt% Li. A proprietary processed 8090 Al-Li alloy MMC sheet aged more rapidly, however, and gave considerably higher strengths. The toughness of Al-Li-Cu-Mg-Zr MMC sheet, as indicated by the notched tensile behaviour, can be improved by reducing the lithium content albeit at the expense of strength.

Effects of lithium doping on textural characteristics of Co3O4 catalyst

The effects of lithium content (0.75%, 3% and 6% Li+) and calcination temperature (400, 500, 600 and 700 °C) on different surface properties of Co3O4 were investigated. The various texture parameters of pure and doped oxide samples were computed from data on nitrogen adsorption at 77 K.The dissolution of monovalent lithium ions in the Co3O4 lattice at temperatures equal to or greater than 700 °C was accompanied by a marked decrease in the surface area, total pore volume and most probable pore radius of the catalyst. In contrast, doping in the temperature range 400 – 600 °C led to a marked increase in the specific surface area of Co3O4; this attained a maximum value at 500 °C (a 94% increase). The most probable pore radius increases for the oxide doped with 0.75% Li then decreases with increasing amount of dopant ions. The total pore volumes of all doped oxide samples are smaller than those measured for pure oxide specimens.The possible mechanisms of doping of Co3O4 with lithium ions are discussed.