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1.
Nanocrystalline materials of Ni0.8Co0.1Mn0.1(OH)2 are successfully synthesized by fast co-precipitation method. The crystalline structure and morphology of the precursors and LiNi0.8Co0.1Mn0.1O2 materials are characterized by XRD, SEM and Rietveld refinement analyses. It is found that the nanocrystalline phase and low crystallinity of Ni0.8Co0.1Mn0.1(OH)2 could help achieve its uniform mixing with lithium source, and further attribute to highly ordered layered LiNi0.8Co0.1Mn0.1O2 with low cation mixing degree. Electrochemical studies confirm that the LiNi0.8Co0.1Mn0.1O2 exhibits a good electrochemical property with initial discharge specific capacity of 192.4 mAh g− 1 at a current density of 18 mA g− 1, and the capacity retention after 40 cycles is 91.56%. This method is a simple and effective method to synthesize cathode material.  相似文献   

2.
Positive electrode material LiNi1/2Mn1/2O2 was synthesized via the carbonate co-precipitation method and the hydroxide precipitation route to study the effects of the precursor on its structural and electrochemical properties. The results of X-ray diffraction and Rietveld refinement show that the carbonate precursor of Ni2+ and Mn2+ exhibits one phase at a pH of 8.5, while the hydroxide deposit separates into Ni(OH)2 and Mn(OH)2 phases under the same experimental conditions. LiNi1/2Mn1/2O2 material prepared from the hydroxide precursor shows 8.9% Li/Ni exchange and a large capacity loss of 11.3% in the first 10 cycles. By contrast, more uniform distribution of transition metal ions and stable Mn2+ in the carbonate precursor contribute to only 7.8% Li/Ni disorder in the obtained LiNi1/2Mn1/2O2, which delivers a reversible capacity of about 182 mAh g−1 at a current rate of 14 mA g−1 between 2.5 and 4.8 V.  相似文献   

3.
A lithium insertion material having the composition LiNi0.3Co0.3Mn0.3Fe0.1O2 was synthesized by simple sol-gel method. The structural and electrochemical properties of the sample were investigated using X-ray diffraction spectroscopy (XRD) and the galvanostatic charge-discharge method. Rietvelt analysis of the XRD patterns shows that this compound can be classified as α-NaFeO2 structure type (R3m; a=2.8689(5) Å and 14.296(5) Å in hexagonal setting). Rietvelt fitting shows that a relatively large amount of Fe and Ni ion occupy the Li layer (3a site) and a relatively large amount of Li occupies the transition metal layer (3b site). LiNi0.3Co0.3Mn0.3Fe0.1O2 when cycled in the voltage range 4.3–2.8 V gives an initial discharge capacity of 120 mAh/g, and stable cycling performance. LiNi0.3Co0.3Mn0.3Fe0.1O2 in the voltage range 2.8–4.5 V has a discharge capacity of 140 mAh/g, and exhibits a significant loss in capacity during cycling. Ex-situ XRD measurements were performed to study the structure changes of the samples after cycling between 2.8–4.3 V and 2.8–4.5 V for 20 cycles. The XRD and electrochemical results suggested that cation mixing in this layered structure oxide could be causing degradation of the cell capacity.  相似文献   

4.
《Ceramics International》2021,47(18):25680-25688
LiNi0.8Co0.1Mn0.1O2 cathode material for lithium-ion battery exhibits high capacity, but it suffers from interfacial side reactions and structural/thermodynamic instability, which leads to capacity reduction and safety problems. Cubic brick (Ni0.8Co0.1Mn0.1)C2O4·2H2O particles with micron size are synthesized by co-precipitation method. The oxalic precursor is sintered with lithium hydroxide to obtain cubic mono-dispersion LiNi0.8Co0.1Mn0.1O2 micrometer particles. Structural stability, cycling performance, rate capability and compacting density of the cubic mono-dispersion material are investigated. Conventional spherical and irregular mono-dispersion LiNi0.8Co0.1Mn0.1O2 are also prepared for comparison. The results reveal that the cubic mono-dispersion LiNi0.8Co0.1Mn0.1O2 dramatically enhances the structural stability and cycling performance at a little cost of capacity and rate capability.  相似文献   

5.
Fine-sized LiNi0.8Co0.15Mn0.05O2 cathode particles with high discharge capacities and good cycle properties were prepared by spray pyrolysis from the polymeric precursor solutions. The cathode particles obtained from the spray solution without polymeric precursors had irregular morphology and hardly aggregated morphology. On the other hand, the cathode particles obtained from the spray solution with citric acid and ethylene glycol had fine size and regular morphologies. The cathode particles obtained from the spray solution containing adequate amounts of citric acid and ethylene glycol had several hundreds nanometer and narrow size distribution. The maximum discharge capacity of the cathode particles was 218 mAh/g when the excess of lithium component added to the spray solution was 6 mol% of the stoichiometric amount to obtain the LiNi0.8Co0.15Mn0.05O2 particles. The discharge capacities of the fine-sized LiNi0.8Co0.15Mn0.05O2 particles dropped from 218 to 213 mAh/g by the 50th cycle at a current density of 0.1 C.  相似文献   

6.
LiNi0.4Co0.3Mn0.3O2 thin film electrodes are fabricated from LiNi0.4Co0.3Mn0.3O2 raw powder at room temperature without pretreatments using aerosol deposition that is much faster and easier than conventional methods such as vaporization, pulsed laser deposition, and sputtering. The LiNi0.4Co0.3Mn0.3O2 thin film is composed of fine grains maintaining the crystal structure of the LiNi0.4Co0.3Mn0.3O2 raw powder. In the cyclic voltammogram, the LiNi0.4Co0.3Mn0.3O2 thin film electrode shows a 3.9-V anodic peak and a 3.6-V cathodic peak. The initial discharge capacity is 44.6 μAh/cm2, and reversible behavior is observed in charge-discharge profiles. Based on the results, the aerosol deposition method is believed to be a potential candidate for the fabrication of thin film electrodes.  相似文献   

7.
In this study, we have successfully coated the CeO2 nanoparticles (CeONPs) layer onto the surface of the Ni-rich layered LiNi0.7Co0.2Mn0.1O2 cathode materials by a wet chemical method, which can effectively improve the structural stability of electrode. The X-ray powder diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS) are used to determine the structure, morphology, elemental composition and electronic state of pristine and surface modified LiNi0.7Co0.2Mn0.1O2. The electrochemical testing indicates that the 0.3?mol% CeO2-coated LiNi0.7Co0.2Mn0.1O2 demonstrates excellent cycling capability and rate performance, the discharge specific capacity is 161.7?mA?h?g?1 with the capacity retention of 86.42% after 100 cycles at a current rate of 0.5?C, compared to 135.7?mA?h?g?1 and 70.64% for bare LiNi0.7Co0.2Mn0.1O2, respectively. Even at 5?C, the discharge specific capacity is still up to 137.1?mA?h?g?1 with the capacity retention of 69.0%, while the NCM only delivers 95.5?mA?h?g?1 with the capacity retention of 46.6%. The outstanding electrochemical performance is assigned to the excellent oxidation capacity of CeO2 which can oxidize Ni2+ to Ni3+ and Mn3+ to Mn4+ with the result that suppress the occurrence of Li+/Ni2+ mixing and phase transmission. Furthermore, CeO2 coating layer can protect the structure to avoid the occurrence of side reaction. The CeO2-coated composite with enhanced structural stability, cycling capability and rate performance is a promising cathode material candidate for lithium-ion battery.  相似文献   

8.
Spherical LiNi1/2Mn1/2O 2 powders were synthesized from LiOH . H2O and coprecipitated metal hydroxide, (Ni1/2Mn1/2)(OH)2. The average particle size of the powders was about 10 m and the size distribution was quite narrow due to the homogeneity of the metal hydroxide, (Ni1/2Mn1/2)(OH)2. The tap-density of the LiNi1/2Mn1/2O2 powders was approximately 2.2 g cm–3, which is comparable to the tap-density of commercial LiCoO2. The LiNi1/2Mn1/2 O2electrode delivered a discharge capacity of 152, 163, 183, and 189 mA h g–1 in the voltage ranges of 2.8–4.3, 2.8–4.4, 2.8–4.5, and 2.8–4.6 V, respectively, with good cyclability. Furthermore, Al(OH)3-coated LiNi1/2Mn1/2O2exhibited excellent cycling behavior and rate capability compared to the pristine electrode.  相似文献   

9.
《Ceramics International》2017,43(4):3885-3892
We report the preparation of a series of LiNi0.8Co0.15Al0.05O2 materials with different reaction time (10, 20, 30 and 40 h) of precursor and their electrochemical properties as cathode material for lithium-ion batteries (LIBs). The preparation of LiNi0.8Co0.15Al0.05O2 was divided into two steps: a co-precipitation process to obtain Ni0.8Co0.15Al0.05(OH)2 precursor and a calcination step with LiOH. During the co-precipitation process, AlO2- was employed as Al source so as to guarantee Ni2+, Co2+ and Al3+ co-precipitation. The impacts of different synthesis time of the precursor on crystal structure, morphology and electrochemical performance of LiNi0.8Co0.15Al0.05O2 were systematically investigated. The samples with various synthesis time of precursor possessed spherical morphology and a layered α-NaFeO2 structure with R-3m space group. Especially, when the reaction time of precursor was 30 h, the LiNi0.8Co0.15Al0.05O2 had the weakest degree of Li+/Ni2+ ions mixing and the best uniformity and integrity. When used as cathode materials for LIBs, the LiNi0.8Co0.15Al0.05O2 with 30 h exhibited high discharge capacity, good cycling performance and remarkable rate capability. The maximum discharge capacity was 202.3 mAh g−1 at 0.1 C and the capacity retention approached 99.4% after 100 cycles at 1 C. At 10 C, the discharge capacity exceeded 140 mAh g−1, suggesting a possible application in the high rate LIBs. The excellent electrochemical performance might be attributed to the uniform co-precipitation of Ni2+, Co2+ and Al3+ and well layered structure with less Li+/Ni2+ mixing.  相似文献   

10.
Spherical Li[Ni1/3Co1/3Mn1/3]O2 powders were synthesized from LiOH·H2O and coprecipitated spherical metal hydroxide, (Ni1/3Mn1/3Co1/3)(OH)2 and coated with Al(OH)3. The Al(OH)3-coated Li[Ni1/3Co1/3Mn1/3]O2 showed a capacity retention of 80% at 320 mA g−1 (2 C-rate) based on 20 mA g−1 (0.1 C-rate), while the pristine Li[Ni1/3Co1/3Mn1/3]O2 delivered only 45% at the same current density. Also, unlike pristine Li[Ni1/3Co1/3Mn1/3]O2, the Al(OH)3-coated Li[Ni1/3Co1/3Mn1/3]O2 cathode exhibits excellent rate capability and good thermal stability.  相似文献   

11.
The Ni-rich LiNi0.83Co0.12Mn0.05O2 (NCM83) cathode materials have drawn intensive attention due to the high energy density and low cost. However, Ni-rich LiNi1-x-yCoxMnyO2 still has the fatal weakness of poor cycle stability, limiting its further wide application. Bulk doping is an effective means to enhance the cycle stability, yet the electrochemical performances are very sensitive to the doping quantity. Here a facile method of co-precipitation is adopted to coat (Ni0.4Co0.2Mn0.4)1-xAlx(OH)2+x on precursor particles of NCM83. Al ions diffuse evenly in the NCM83 particles after sintering. The cells are operated at a high cut-off voltage of 4.5 V. The discharge capacity of NCM83 is 187.8 mAh g?1, and decays fast with cycles. The doped sample even exhibits a higher discharge capacity of 195 mAh g?1, and the capacity retention is improved to 83.8% after 200 cycles.  相似文献   

12.
《Ceramics International》2022,48(12):17279-17288
Layered high-nickel LiNi0.8Co0.1Mn0.1O2 is a promising candidate of the next generation cathode materials for lithium-ion batteries. However, severe cycling instability and fast capacity drop induced by anisotropic structured change restrict its wide application. To address these defects, the structure design of cathodes is conducted. Herein, a hierarchical layered LiNi0.8Co0.1Mn0.1O2 cathode consisting of orderly stacking hexagonal nanosheets with exposed active {104} facets is successfully synthesized by an improved co-precipitation process and followed with a high temperature lithiation reaction. Benefiting from this unique texture, exposed active {104} facets with lower surface energy supply 3D barrier-free Li+ ion diffusion channels, significantly improving the efficiency of the Li+ diffusion. Moreover, the consistent arrangement of nanosheets in the manner of the {001} facets close attachment is beneficial to alleviate the stress caused by the anisotropic structured change. Thus, this cathode material presents both superior reversible capability (203.8 mAh g?1 at 0.1C, 184.5 mAh g?1 at 1 C, 173.0 mAh g?1 at 5 C and 161.3 mAh g?1 at 10 C) and stable cycling performance (capacity retention of 89.3% after 100 cycles at 1 C, 55.3% after 300 cycles at 5 C and 59.6% after 300 cycles at 10 C).  相似文献   

13.
《Ceramics International》2019,45(15):18965-18971
Different calcination atmospheres of air, 50% oxygen (vs. N2) and pure oxygen have been used to prepare special LiNi0.8Co0.1Mn0.1O2 cathode materials to observe the influence of oxygen composition. To investigate the structure and electrochemical property of the samples using different oxygen compositions, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), cycling performance tests and electrochemical impedance spectroscopy (EIS) were carried out. XRD, SEM, and XPS results show that the sample made using higher oxygen composition has less cation mixing and lower levels of Ni2+. However, both samples have almost the same oxygen environments on their surfaces as well as micro-morphology and size. The sample with a higher oxygen composition shows better electrochemical performance. Interestingly, the electrochemical performance of the sample made using 50% oxygen is similar to that made with pure oxygen and much better than the sample made with air. It has a specific capacity of 202.4 mAh g−1 at 0.1C and a capacity retention of 85.2% after 300 cycles at 1C, which may be meaningful for balancing cost and performance.  相似文献   

14.
Titanium and boron are simultaneously introduced into LiNi0.8Co0.1Mn0.1O2 to improve the structural stability and electrochemical performance of the material. X-ray diffraction studies reveal that Ti4+ ion replaces Li+ ion and reduces the cation mixing; B3+ ion enters the tetrahedron of the transition metal layers and enlarges the distance of the [LiO6] layers. The co-doped sample has spherical secondary particles with elongated and enlarged primary particles, in which Ti and B elements distribute uniformly. Electrochemical studies reveal the co-doped sample has improved rate performance (183.1 mAh·g-1 at 1 C and 155.5 mAh·g-1 at 10 C) and cycle stability (capacity retention of 94.7% after 100 cycles at 1 C). EIS and CV disclose that Ti and B co-doping reduces charge transfer impedance and suppresses phase change of LiNi0.8Co0.1Mn0.1O2.  相似文献   

15.
Elemental doping for substituting lithium or oxygen sites has become a simple and effective technique to improve the electrochemical performance of layered cathode materials. Compared with single-element doping, this work presents an unprecedented contribution to the study of the effect of Na+/F co-doping on the structure and electrochemical performance of LiNi1/3Mn1/3Co1/3O2. The co-doped Li1-zNazNi1/3Mn1/3Co1/3O2-zFz (z = 0.025) and pristine LiNi1/3Co1/3Mn1/3O2 materials were synthesized via the sol–gel method using EDTA as a chelating agent. Structural analyses, carried out by X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy, revealed that the Na+ and F dopants were successfully incorporated into the Li and O sites, respectively. The co-doping resulted in larger Li-slab spacing, a lower degree of cation mixing, and the stabilization of the surface structure, which substantially enhanced the cycling stability and rate capability of the cathode material. The Na/F co-doped LiNi1/3Mn1/3Co1/3O2 electrode delivered an initial specific capacity of 142 mAh g−1 at a 1C rate (178 mAh g−1 at 0.1C), and it maintained 50% of its initial capacity after 1000 charge–discharge cycles at a 1C rate.  相似文献   

16.
A cathode material for lithium-ion batteries–LiNi1/3Co1/3Mn1/3O2–was prepared by solution combustion synthesis and characterized by XRD, SEM, and galvanostatic charge/discharge cycling. The sample calcined at 950°C for 10 h showed best charge/discharge performance. An initial discharge capacity (C) of 150.5 mA h g–1 retained 95.7% of its value after 75 charge/discharge cycles at Ic = 14 mA g–1 (0.2C rate), Id = 70 mA g–1 (0.5C rate).  相似文献   

17.
The optimum conditions for synthesizing LiNi1-y Co y O2 (y=0.1, 0.3 and 0.5) by a simplified combustion method, in which the preheating step is omitted, and the electrochemical properties of these materials were investigated. The optimum condition for synthesizing LiNi0.9Co0.1O2 by the simplified combustion method is calcination at 800 °C for 12 h in air in 3.6 mole ratio of urea to nitrate. The LiNi0.9Co0.1O2 synthesized under these conditions shows the smallest R-factor{(I 006+I 102)/I 101} and the largest I 003/I 104, indicating better hexagonal ordering and less cation mixing, respectively. The LiNi0.7Co0.3O2 synthesized at 800 °C for 12 h in air in 3.6 mole ratio of urea to nitrate has the largest first discharge capacity 156.2 mA h g−1 at 0.5C and shows relatively good cycling performance. This sample shows better hexagonal ordering and less cation mixing than the other samples. The particle size of the LiNi0.7Co0.3O2 is relatively small and its particles are spherical with uniform particle size.  相似文献   

18.
In this study, spheroid LiNi1/3Co1/3Mn1/3O2 (NCM111) cathode material were synthesized using LiOH with Ni0.5Co0.2Mn0.3(OH)2 precursor by a simple solid-state reaction, and characterized by X-ray diffraction and scanning electron microscopy. Electrochemical behavior of NCM111 was investigated by electrochemical impedance spectroscopy (EIS) combining with cyclic voltammogram (CV) and charge/discharge test in the 1 M LiPF6-EC:EMC electrolyte with ethylene sulfate (DTD) and methylene methanedisulfonate (MMDS) additives either singly or in combination with high cutoff voltage of 3.0–4.5 V at room temperature of 25 °C or elevated temperature of 55 °C. It was found that DTD additive can increase the initial coulombic efficiency of NCM111, and the spheroid NCM111 can obtain the maximum initial discharge capacity of 177.81 mAh/g with the 2 wt% DTD, and keep 92.29% capacity retention after 80 cycles. The MMDS additives would decrease the initial discharge capacity of the NCM111, and enhance significantly long cycle life of the NCM111 with the capacity retention of 99.23% over 80 cycles at high voltage of 4.5 V. The additive combination 2 wt% DTD?+?1 wt% MMDS was an optimal additive combination, demonstrating the 102.2% capacity retention over 80 cycles at room temperature and the 94.2% capacity retention over 70 cycles at elevated temperature of 55 °C. EIS results revealed that the additive blend of 2 wt% DTD?+?1 wt% MMDS can drastically lower the kinetics impedance and suppress the growth rate of R ct for the NCM111 electrode.  相似文献   

19.
A layered LiNi0.8Co0.2O2 solid solution, which is a promising cathode material for secondary lithium batteries, was successfully synthesized by an emulsion drying method. Because electrochemical properties significantly depend on the conditions of the synthesis, the calcination temperature was carefully determined on the basis of X-ray diffraction and TG studies. The prepared cathodes were characterized by means of SEM, BET, X-ray diffraction, Rietveld refinement, cyclic voltammetry and a charge-discharge experiment. From the Rietveld analysis, it was found that powder calcined at 800 °C for 12 h exhibits a well ordered and lower cation mixed layered structure than the others. The cyclic voltammetry experiment shows that phase transformation can be suppressed considerably by increasing the calcination temperature to 800 °C. The highest discharge capacity of 188.4 mA h g−1 was obtained from the sample prepared at 800 °C. Furthermore, a high capacity retention ratio of 88.1% was found for the initial value after 50 cycles at a constant current density of 40 mA g−1 between 2.7 VLi/Li+ and 4.3 VLi/Li+. In the rate capability test, the cathode delivered a higher discharge capacity of 153.1 mA h g−1 at a 4 C (800 mA g−1) rate.  相似文献   

20.
《Ceramics International》2019,45(1):674-680
Nickel-rich lithium material LiNixCoyMn1-x-yO2(x > 0.6) becomes a new research focus for the next-generation lithium-ion batteries owing to their high operating voltage and high reversible capacity. However, the rate performance and cycling stability of these cathode materials are not satisfactory. Inspired by the characteristics of Y2O3 production, a new cathode material with ultrathin-Y2O3 coating was introduced to improve the electrochemical performance and storage properties of LiNi0.8Co0.1Mn0.1O2 for the first time. XRD, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS) and XPS were used to mirror the crystal and surface of LiNi0.8Co0.1Mn0.1O2 particles, results i that a uniform interface formed on as-prepared material. The impacts on the electrochemical properties with or without Y2O3 coating are discussed in detail. Notably, galvanostatic discharge-charge tests appear that Y2O3-coated sample especially 3% coating displayed a better capacity retention rate of 91.45% after 100 cycles than the bare one of 85.07%.  相似文献   

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