Properties Of LiNi0 Research Articles

The influence of different drying methods on the properties of LiNi0.5Mn1.5O4 material

It was precisely because LiNi[Formula: see text]Mn[Formula: see text]O4 cathode material had many advantages, including high voltage, high power, no pollution, low cost, etc., that it became a research hotspot for lithium-ion cathode materials. Although LiNi[Formula: see text]Mn[Formula: see text]O4 has a three-dimensional Li[Formula: see text] diffusion channel, there are still some problems that lead to capacity decay and reduced cycling stability, limiting its commercial application. In this paper, the LiNi[Formula: see text]Mn[Formula: see text]O4 cathode material was prepared by the freezing precipitation method. We studied the effects of different drying methods, such as blast drying, water bath drying and freeze-drying on the structure, morphology and electrochemical properties of LiNi[Formula: see text]Mn[Formula: see text]O4 cathode materials. The study found that the LiNi[Formula: see text]Mn[Formula: see text]O4 cathode material prepared by the precipitation-freeze-drying method had a complete crystal form, a stable structure and no LixNi[Formula: see text]O impurity peak. The SEM image showed that the particles were smaller and had a smooth surface. The initial discharge-specific capacity at 0.1[Formula: see text]C was 105.2[Formula: see text]mAh⋅g[Formula: see text]. After 50 cycles, its specific discharge capacity was 99.4[Formula: see text]mAh⋅g[Formula: see text] and the capacity retention rate was 94.5%. Compared with LiNi[Formula: see text]Mn[Formula: see text]O4 materials prepared by other methods, it had better electrochemical performance.

The Effects of Ru4+ Doping on LiNi0.5Mn1.5O4 with Two Crystal Structures.

Doping of Ru has been used to enhance the performance of LiNi0.5Mn1.5O4 cathode materials. However, the effects of Ru doping on the two types of LiNi0.5Mn1.5O4 are rarely studied. In this study, Ru4+ with a stoichiometric ratio of 0.05 is introduced into LiNi0.5Mn1.5O4 with different space groups (Fdm, P4332). The influence of Ru doping on the properties of LiNi0.5Mn1.5O4 (Fdm, P4332) is comprehensively studied using multiple techniques such as XRD, Raman, and SEM methods. Electrochemical tests show that Ru4+-doped LiNi0.5Mn1.5O4 (P4332) delivers the optimal electrochemical performance. Its initial specific capacity reaches 132.8 mAh g−1, and 97.7% of this is retained after 300 cycles at a 1 C rate at room temperature. Even at a rate of 10 C, the capacity of Ru4+-LiNi0.5Mn1.5O4 (P4332) is still 100.7 mAh g−1. Raman spectroscopy shows that the Ni/Mn arrangement of Ru4+-LiNi0.5Mn1.5O4 (Fdm) is not significantly affected by Ru4+ doping. However, LiNi0.5Mn1.5O4 (P4332) is transformed to semi-ordered LiNi0.5Mn1.5O4 after the incorporation of Ru4+. Ru4+ doping hinders the ordering process of Ni/Mn during the heat treatment process, to an extent.

Synthesis and electrochemical performance of Mo-doped LiNi0.5Mn1.5O4 cathode material

ABSTRACT The Mo-doped LiNi0.5Mn1.5O4 material has been successfully synthesized by the freezing precipitation method, and the effect of different doping amounts on the properties of LiNi0.5Mn1.5O4 material has been studied. Texting has included XRD, SEM, first charge and discharge curves, cycle performance, rate cycle, CV analysis, and EIS analysis. The experimental results show that the Mo-doping material shows superior performance when the doping amount is 1%, and this amount ensures the highest capacity of the sample. The capacity is 120.1 mAh g−1 at 0.1 C (initial discharge), with which the particle size and the dispersion are uniform. After 50 cycles, the discharge capacity is 118.3 mAh g−1 at 0.1 C, and the capacity retention rate is 98.5%. These results reveal that Mo-doped LiNi0.5Mn1.5O4 contributes to the outstanding electrochemical performance of the LiNi0.5Mn1.5O4.

Synergistically Enhanced Electrochemical Properties of LiNi0.5Co0.2Mn0.3O2 by the Co-Modification of Ti and Na

The layered material of nickel cobalt manganese oxide lithium oxide is one of the most promising lithium-ion battery (LIBs) materials, with the characteristics of high capacity and high density. However, most nickel-rich layered oxides have the phenomenon of cation mixing and the phenomenon that the layered structure changes to the spinel structure during the cycle, which results in poor capacity and cycle performance under high cut-off voltage. Herein, we modified LiNi[Formula: see text]Co[Formula: see text]Mn[Formula: see text]O2 with Ti and Na co-doping to observe the changes in the specific capacity, cycle performance and crystal structure of the material. Ti and Na co-doped LiNi[Formula: see text]Co[Formula: see text]Mn[Formula: see text]O2 has the most obvious effect on increasing the discharge specific capacity and improving the cycle performance. In sthe voltage range of 3–4.5[Formula: see text]V, its discharge specific capacity reaches 183.5[Formula: see text]mAh/gat 0.5C, and the capacity retention rate after 100 cycles is 81.96%, and its discharge specific capacity reaches 164.2[Formula: see text]mAh/g at 1C and after 100 cycles Capacity retention rate is 80.93%. The introduction of Ti and Na plays an important role in improving the cation mixing phenomenon and improving the stability of the crystal structure.

Improved cyclability of Nickel-rich layered oxides

This study compares the physico- and electro- chemical properties of LiNi0.8Mn0.10Co0.1O2 (NMC811) and LiNi0.83Mn0.06Co0.09Al0.1O2 (NMCA) prepared by an oxalic acid co-precipitation. Deposition of a SiO2 surface coating was attempted via reaction of the powder with an amino silane prior to the final heat treatment. It was found that either the presence of small amounts of Al3+, or the compositional gradient resulting from a two step co-precipitation, caused increased crystal growth of the NMCA in comparison to NMC811. This led to improved cyclability in LP40 electrolyte. However, the SiO2 coating appeared incomplete and negatively impacted performance. Crystal cleavage preferably on the 001 planes was observed after 100 charge-discharge cycles, with consequent cathode electrolyte interphase formation in the crystal cracks. This is believed to cause capacity decay via lithium loss, and increased charge transfer resistance. An FEC based electrolyte improved the cyclability in all cases and even under extreme conditions (45°C and upper cycling potential of 4.5 V) NMCA showed a capacity retention of 85% after 100 cycles.

Study on modification of LiNi0.5Mn1.5O4 by ultrasonic chemical method

This paper briefly describes the preparation of LiNi0.5Mn1.5O4 by ultrasonic chemistry and its doping modification. The physical and electrochemical properties of LiNi0.5Mn1.5O4 were studied by SEM and electrochemical tests. The results show that the particles doped with graphene had smaller particle size and uniform distribution. The initial discharge specific capacity of 0.1C was 187 mAh g−1. The discharge specific capacity after 30 cycles was 181 mAh g−1, and the capacity retention rate was 97%. Graphene-doped samples had high capacity, excellent rate performance, and significant cycle stability.

Dilution Effects of Highly Concentrated Dimethyl Carbonate-Based Electrolytes with a Hydrofluoroether on Charge/Discharge Properties of LiNi0.8Co0.1Mn0.1O2 Positive Electrode

In highly concentrated LiBF4/dimethyl carbonate (DMC) electrolyte, Ni-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) positive-electrode exhibited a good cycle performance and the crack formation in NCM811 particles was remarkably suppressed. However, the high concentration causes some problems, such as a high viscosity, a low ionic conductivity and a high cost. To solve these problems, we chose 1,1,2,2–tetrafluoroethyl 2,2,3,3–tetrafluoropropyl ether (HFE) to dilute the concentrated LiBF4/ and LiPF6/DMC systems. The cycle performance of NCM811 electrode remarkably deteriorated in 0.96 mol kg−1 LiBF4/DMC+HFE (1:2 by volume). Raman spectra indicated that the fraction of free DMC increased in the diluted electrolyte, which led to instability against oxidation. However, in the LiPF6/DMC system, the fraction of free DMC had rarely increased after diluted with HFE. The diluted electrolyte showed a high stability against oxidation comparable to the nearly saturated electrolyte, and the NCM811 electrode showed an excellent cycle performance.

Influence of Calcination Temperature on Structure and Electrochemical Behavior of LiNi0.83 Co0.11Mn0.06O2 Cathodes for Lithium-Ion Batteries

Nickel-rich layered oxides (Ni ≥60%) are considered as the most promising cathode materials for lithium-ion batteries due to its high energy density and low cost. However, its cycling performance is seriously influenced by the synthesis condition, like the sintering temperature, time and atmosphere. Herein, we investigate different properties of LiNi0.83Co0.11Mn0.06O2 (LNCMO) sintered from 720 to780 °C, and the cathode calcined at 760 °C display the most perfect layered structure and the uniform distribution of primary particles size. Therefore, the LNCMO sintered at 760 °C exhibited the best rate capability of 118 mAh·g-1 at 10 C and the highest capacity retention of 95.44 % after 100 cycles at 1 C. Our results indicate that the cycling performance and rate capability of LNCMO are heavily depended on the sintering temperature.

Washing effect on properties of LiNi0.8Co0.15Al0.05O2 cathode material by ethanol solvent

Abstract Different LiNi0.8Co0.15Al0.05O2 cathode materials were washed by ethanol solvent. Inductively coupled plasma atomic emission spectroscopy (ICP-AES), Fourier transformed infrared (FTIR) spectrum, X-ray diffraction (XRD), scanning electron microscopy (SEM), charge–discharge test and electrochemical impedance spectroscopy (EIS) were used to evaluate the elemental contents, structures, morphologies and electrochemical properties of samples. The results show that ethanol washing can remove effectively the synthetic residues LiOH/Li2O on the freshly-prepared LiNi0.8Co0.15Al0.05O2 and make the sample much more resistant to H2O and CO2, without destroying its bulk structure, surface morphology and electrochemical performances. Moreover, the discharge specific capacity and cycle performance of LiNi0.8Co0.15Al0.05O2 after storage in air with a relative humidity of 80% for three months are improved by immediate ethanol washing.

Surface Treatment on Structure and Property of LiNi0.8Co0.15Al0.05O2 by Silane Coupling Agent

Surface Treatment on Structure and Property of LiNi_0.8Co_0.15Al_0.05O₂ by Silane Coupling Agent

Investigation on LiNi0.5Mn1.5O4 cathode material based on the precursor of nickel-manganese compound for lithium-ion battery

The high-voltage spinel LiNi0.5Mn1.5O4 (LNMO) with submicron particle size (LNMO-8505P70010) has been synthesized based on nickel-manganese compound, which is obtained from pre-sintering the nickel-manganese hydroxide precipitation at 850 °C. The LNMO materials based on nickel-manganese hydroxide (LNMO-70010, LNMO-850570010, and LNMO-8501070010) have also been synthesized for comparison to study the pre-sintering impact on the properties of LiNi0.5Mn1.5O4 material. The morphologies and structures of the obtained samples have been analyzed by X-ray powder diffraction and scanning electron microscopy. The nickel-manganese compound has a spinel structure with high crystallinity, making it a good precursor to form high-performance LNMO with lower content of Mn3+ and impurity. The obtained LNMO-8505P70010 delivers discharge capacities of 125.4 mA h g−1 at 0.2 C, and the capacity retention of 15 C reaches 73.8 % of the capacity retention of 0.2​ C. Furthermore, it shows a superior cyclability with the capacity retention of 96.4 % after 150 cycles at 5 ​C. Compared with the synthesis method without pre-sintering, the synthesis method with pre-sintering can save energy while reaching the same discharge specific capacity.

Improving the electrochemical performances of spherical LiNi0.5Mn1.5O4 by Fe2O3 surface coating for lithium-ion batteries

The spherical LiNi0.5Mn1.5O4 cathode material synthesized by a co-precipitation method has been modified by Fe2O3 through a simple chemical precipitation method. The effects of Fe2O3 coating on the structure and property of LiNi0.5Mn1.5O4 cathode have been carefully investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and atomic absorption spectroscopy (AAS). The results show that the Fe2O3 coating layer covered the surfaces of the spherical LiNi0.5Mn1.5O4 particles does not change the crystallographic structure of LiNi0.5Mn1.5O4, but it can protect the surface of the active materials from electrolyte erosion and suppresses the dissolution of transition metal elements. The effects of Fe2O3 coating layer on the electrochemical performances of LiNi0.5Mn1.5O4 have also been investigated systematically by the charge-discharge testing and AC impedance spectroscopy. Compared with the pristine LiNi0.5Mn1.5O4, the Fe2O3 modified material exhibits remarkably enhanced cyclic stability and excellent rate capability. In addition, surface modification of the LiNi0.5Mn1.5O4 is found to be an effective route for suppressing the increase of the impedance during the storage process at elevated temperatures.

Effect of sodium additive on electrochemical properties of LiNi<SUB>0.5</SUB> Mn<SUB>1.5</SUB>O<SUB>4</SUB> for high-power lithium-ion batteries

Effect of sodium additive on electrochemical properties of LiNi<SUB>0.5</SUB> Mn<SUB>1.5</SUB>O<SUB>4</SUB> for high-power lithium-ion batteries

Effects of Washing and Heat-treatment on Structure and Electrochemical Charge/Discharge Property for LiNi$lt;inf$gt;0.8$lt;/inf$gt;Co$lt;inf$gt;0.15$lt;/inf$gt;Al$lt;inf$gt;0.05$lt;/inf$gt;O$lt;inf$gt;2$lt;/inf$gt; Powder

The effect of washing on electrochemical properties of Ni-rich layered cathode LiNi0.8Co0.15Al0.05O2 powder is widely known, but few literatures have reported thoroughly. Primitive LiNi0.8Co0.15Al0.05O2 powders processed by deionized water and heat-treatment at different temperatures in a paralleling time was explored for the first time. Sig- nificant changes of structure, morphology and electrochemical charge/discharge property of the LiNi0.8Co0.15Al0.05O2 cathode were detected comprehensively. Mechanism of washing and heat-treatment on the structure and electrochemi- cal charge/discharge property and the rate performance were studied. XRD patterns show the I(003)/I(104) value of LiNi0.8Co0.15Al0.05O2 powders decreases and the volume turns smaller after being washed and heat-treated. FT-IR spec- tra confirm the existence of lithium carbonate, and nickel compounds and their relative changes in the LiNi0.8Co0.15Al0.05O2 powders. The specific capacity and rate performance of the LiNi0.8Co0.15Al0.05O2 powders were carried out before and after washing and heat-treatment. The capacities of primitive sample and treated samples remain 88.87%, 87.21%, 85.43% and 87.80% after 30 cycles, respectively.

Properties of LiNi0.8Co0.1Mn0.1O2 as a high energy cathode material for lithium-ion batteries

Nickel-rich layered materials are prospective cathode materials for use in lithium-ion batteries due to their higher capacity and lower cost relative to LiCoO2. In this work, spherical Ni0.8Co0.1Mn0.1(OH)2 precursors are successfully synthesized through a co-precipitation method. The synthetic conditions of the precursors - including the pH, stirring speed, molar ratio of NH4OH to transition metals and reaction temperature - are investigated in detail, and their variations have significant effects on the morphology, microstructure and tap-density of the prepared Ni0.8Co0.1Mn0.1 (OH)2 precursors. LiNi0.8Co0.1Mn0.1O2 is then prepared from these precursors through a reaction with 5% excess LiOH· H2O at various temperatures. The crystal structure, morphology and electrochemical properties of the Ni0.8Co0.1Mn0.1 (OH)2 precursors and LiNi0.8Co0.1Mn0.1O2 were investigated. In the voltage range from 3.0 to 4.3 V, LiNi0.8Co0.1Mn0.1O2 exhibits an initial discharge capacity of 193.0mAh g-1 at a 0.1 C-rate. The cathode delivers an initial capacity of 170.4 mAh g-1 at a 1 C-rate, and it retains 90.4% of its capacity after 100 cycles.

Impacts of neodymium on structural, spectral and dielectric properties of LiNi0.5Fe2O4 nanocrystalline ferrites fabricated via micro-emulsion technique

Soft ferrites are technologically advanced smart materials and their properties can be tailored by controlling the chemical composition and judicial choice of the metal elements. In this article we discussed the effect of rare earth neodymium (Nd3+) on various properties of LiNi0.5NdxFe2−xO4 spinel ferrites. These ferrites have been synthesized by facile micro-emulsion route and characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), a.c. electrical conductivity and thermal analysis. The influence of Nd3+ doping on structural and electrical parameters has been investigated. XRD analysis revealed the formation of single cubic spinel structure for x≤0.07. Few traces of secondary phase (NdFeO3) were found for x≥0.105. The secondary phase induced owing to the solubility limit of Nd3+ cations in these ferrites. The lattice parameter (a) and crystallite size (D) both exhibit non-linear relation. The values of “a” and “D” were found in the range 8.322–8.329Å and 25–32nm respectively. These variations were attributed to the larger ionic radius of Nd3+ cations as compared to the host cations and lattice strain produced in these ferrites. The dielectric parameters were studied in the range 1MHz to 3GHz and these parameters were damped by Nd3+ incorporation and also by increasing the frequency. The reduced dielectric parameters observed in wide frequency range proposed that these nanocrystalline ferrites are potential candidates for fabricating the devices which are required to operate at GHz frequencies.

Electrochemical properties of LiNi0.5Mn1.3Ti0.2O4/Li4Ti5O12 cells

Spinel compounds LiNi0.5Mn1.3Ti0.2O4 (LNMTO) and Li4Ti5O12 (LTO) were synthesized by different methods. The particle sizes of LNMTO and LTO are 0.5–2 and 0.5–0.8 μm, respectively. The LNMTO/LTO cell exhibits better electrochemical properties at both a low current rate of 0.2C and a high current rate of 1C. When the specific capacity was determined based on the mass of the LNMTO cathode, the LNMTO/LTO cell delivered 137 mA·h·g−1 at 0.2C and 118.2 mA·h·g−1 at 1C, and the corresponding capacity retentions after 30 cycles are 88.5% and 92.4%, respectively.

Magnetic properties of LiNi0.5Mn0.47Al0.03O2 as positive electrode for Li-ion batteries

The layered LiNi0.5Mn0.47Al0.03O2 was synthesized by wet chemical method and characterized by X-ray diffraction and analysis of magnetic measurements. The powders adopted the α-NaFeO2 structure. This substitution of Al for Mn promotes the formation of Li(Ni0.472+Ni0.033+Mn0.474+Al0.033+)O2 structures and induces an increase in the average oxidation state of Ni, thereby leading to the shrinkage of the lattice unit cell. The concentration of antisite defects in which Ni2+ occupies the (3a) Li lattice sites in the Wyckoff notation has been estimated from the ferromagnetic Ni2+(3a)–Mn4+(3b) pairing observed below 140 K. The substitution of 3% Al for Mn reduces the amount of antisite defects from 7% to 6.4–6.5%. The analysis of the magnetic properties in the paramagnetic phase in the framework of the Curie–Weiss law agrees well with the combination of Ni2+ (S = 1), Ni3+ (S = 1/2) and Mn4+ (S = 3/2) spin-only values. Delithiation has been made by the use of K2S2O8. According to this process, known to be softer than the electrochemical one, the nickel ions in the (3b) sites are converted into Ni4+ in the high spin configuration, while Ni2+(3a)–Mn4+(3b) ferromagnetic pairs remain, as the Li+(3b) ions linked to the Ni2+(3a) ions in the antisite defects are not removed. The results show that the antisite defect is surrounded by Mn4+ ions, implying the nonuniform distribution of the cations in agreement with previous NMR and neutron experiments.

Synthesis and electrochemical properties of LiNi0.5Mn1.5O4 as a 5 V cathode material for lithium ion batteries

LiNi0.5Mn1.5O4 as a 5 V cathode material for a lithium-ion battery was synthesized by solution evaporation process in this paper. Thermal gravimetric analysis of the precursor compounds was carried out. X-ray diffraction and scanning electron microscope were used for studying the structure and the morphology of the LiNi0.5Mn1.5O4 materials. Cyclic voltammograms and charge–discharge curves were obtained for presenting the electrochemical performances of LiNi0.5Mn1.5O4. Experimental results show that the discharge capacity and capacity retention of the LiNi0.5Mn1.5O4 prepared by solution evaporation process are superior to the LiNi0.5Mn1.5O4 obtained by melting salt method. The effects of different sintering temperatures on the electrochemical properties of the LiNi0.5Mn1.5O4 electrode materials synthesized by a solution evaporation process were also systematically investigated. With the raising of the sintering temperature, the size of the LiNi0.5Mn1.5O4 gradually increases, its crystallinity is enhanced and the surface morphology of grain is gradually neatened. Electrochemical test results show that the LiNi0.5Mn1.5O4 prepared at 800 °C has the best cycle reversibility, the highest discharge capacity and the optimal capacity retention.

Preparation and properties of LiNi 0.5Mn 0.5O 2 thin films by spin-coating for lithium micro-batteries

LiNi 0.5Mn 0.5O 2 thin films were successfully prepared by a sol–gel spin-coating method. SEM results revealed that the annealed films have a relatively smooth and dense surfaces, along with small grains with homogeneous distribution. The crystallinity and the grain size of thin films increase as the annealing temperature enhanced. The initial discharge capacity enhances from 13 to 46 μAh/cm 2μm when the drying temperature increases from 700 to 800 °C.