共查询到20条相似文献,搜索用时 31 毫秒
1.
The LiNi1/3Co1/3Mn1/3O2/Ag composite used for cathode material of lithium ion battery was prepared by thermal decomposition of AgNO3 added to commercial LiNi1/3Co1/3Mn1/3O2 powders to improve the electrochemical performance of LiNi1/3Mn1/3Co1/3O2. Structure and morphology analysis showed that Ag particles were dispersed on the surface of LiNi1/3Co1/3Mn1/3O2 instead of entering the crystal structure. The results of charge–discharge tests showed that Ag additive could improve the cycle performance and high-rate discharge capability of LiNi1/3Mn1/3Co1/3O2. Extended analysis indicated that Ag was unstable in the commercial electrolyte at high potential. The improved electrochemical performance caused by Ag additive was associated not only with the enhancement of electrical conductivity of the material and the lower polarization of the cell, but also with the increased “c” parameter of LiNi1/3Mn1/3Co1/3O2 after repeated charge/discharge cycles and the compact and protective SEI layer formed on the surface of LiNi1/3Mn1/3Co1/3O2. 相似文献
2.
The structural changes of the composite cathode made by mixing spinel LiMn2O4 and layered LiNi1/3Co1/3Mn1/3O2 in 1:1 wt% in both Li-half and Li-ion cells during charge/discharge are studied by in situ XRD. During the first charge up to ∼5.2 V vs. Li/Li+, the in situ XRD spectra for the composite cathode in the Li-half cell track the structural changes of each component. At the early stage of charge, the lithium extraction takes place in the LiNi1/3Co1/3Mn1/3O2 component only. When the cell voltage reaches at ∼4.0 V vs. Li/Li+, lithium extraction from the spinel LiMn2O4 component starts and becomes the major contributor for the cell capacity due to the higher rate capability of LiMn2O4. When the voltage passed 4.3 V, the major structural changes are from the LiNi1/3Co1/3Mn1/3O2 component, while the LiMn2O4 component is almost unchanged. In the Li-ion cell using a MCMB anode and a composite cathode cycled between 2.5 V and 4.2 V, the structural changes are dominated by the spinel LiMn2O4 component, with much less changes in the layered LiNi1/3Co1/3Mn1/3O2 component, comparing with the Li-half cell results. These results give us valuable information about the structural changes relating to the contributions of each individual component to the cell capacity at certain charge/discharge state, which are helpful in designing and optimizing the composite cathode using spinel- and layered-type materials for Li-ion battery research. 相似文献
3.
SrF2-coated LiNi1/3Co1/3Mn1/3O2 cathode materials with improved cycling performance over 2.5–4.6 V were investigated. The structural and electrochemical properties of the materials were studied using X-ray diffraction (XRD), scanning electron microscope (SEM), charge–discharge tests and electrochemical impedance spectra (EIS). The results showed that the crystalline SrF2 with about 10–50 nm particle size is uniformly coated on the surface of LiNi1/3Co1/3Mn1/3O2 particles. As the coating amount increased from 0.0 to 2.0 mol%, the initial capacity and rate capability of the coated LiNi1/3Co1/3Mn1/3O2 decreased slightly owing to the increase of the charge-transfer resistance; however, the cycling stability was improved by suppressing the increase of the resistance during cycling. 4.0 mol% SrF2-coated LiNi1/3Co1/3Mn1/3O2 showed remarkable decrease of the initial capacity. 2.0 mol% coated sample exhibited the best electrochemical performance. It presented an initial discharge capacity of 165.7 mAh g−1, and a capacity retention of 86.9% after 50 cycles at 4.6 V cut-off cycling. 相似文献
4.
Submicron-sized LiNi1/3Co1/3Mn1/3O2 cathode materials were synthesized using a simple self-propagating solid-state metathesis method with the help of ball milling and the following calcination. A mixture of Li(ac)·2H2O, Ni(ac)2·4H2O, Co(ac)2·4H2O, Mn(ac)2·4H2O (ac = acetate) and excess H2C2O4·2H2O was used as starting material without any solvent. XRD analyses indicate that the LiNi1/3Co1/3Mn1/3O2 materials were formed with typical hexagonal structure. The FESEM images show that the primary particle size of the LiNi1/3Co1/3Mn1/3O2 materials gradually increases from about 100 nm at 700 °C to 200–500 nm at 950 °C with increasing calcination temperature. Among the synthesized materials, the LiNi1/3Co1/3Mn1/3O2 material calcined at 900 °C exhibits excellent electrochemical performance. The steady discharge capacities of the material cycled at 1 C (160 mA g−1) rate are at about 140 mAh g−1 after 100 cycles in the voltage range 3–4.5 V (versus Li+/Li) and the capacity retention is about 87% at the 350th cycle. 相似文献
5.
Shao-Kang Hu Geng-Hao Cheng Ming-Yao Cheng Bing-Joe Hwang Raman Santhanam 《Journal of power sources》2009
A modified synthesis process was developed based on co-precipitation method followed by spray drying process. In this process, a spherical shaped (Co1/3Ni1/3Mn1/3)(OH)2 precursor was synthesized by co-precipitation and pre-heated at 500 °C to form a high structural stability spinel (CoNiMn)O4 to maintain its shape for further processing. The spherical LiNi1/3Co1/3Mn1/3O2 was then prepared by spray drying process using spherical spinel (CoNiMn)O4. LiNi1/3Co1/3Mn1/3O2 powders were then modified by coating their surface with a uniform and nano-sized layer of ZrO2. The ZrO2-coated LiNi1/3Co1/3Mn1/3O2 material exhibited an improved rate capability and cycling stability under a high cut-off voltage of 4.5 V. X-ray diffraction (XRD) measurements revealed that the material had a well-ordered layered structure and Zr was not doped into the LiNi1/3Co1/3Mn1/3O2. Electrochemical impedance spectroscopy measurements showed that the coated material has stable cell resistance regardless of cycle number. The interrupt charging/discharging test indicated that the ZrO2 coating can suppress the polarization effects during the charging and discharging process. From these results, it is believed that the improved cycling performance of ZrO2-coated LiNi1/3Co1/3Mn1/3O2 is attributed to the ability of ZrO2 layer in preventing direct contact of the active material with the electrolyte resulting in a decrease of electrolyte decomposition reactions. 相似文献
6.
LiNi1/3Co1/3Mn1/3O2 has aroused much interest as a new generation of cathode material for Li-ion batteries, due to its great advantages in capacity, stability, low cost and low toxicity, etc. Here we report a novel single-crystalline spherical LiNi1/3Co1/3Mn1/3O2 material that is prepared by a convenient rheological phase reaction route. The X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy indicate that the particles are highly dispersed with spherical morphologies and diameters of about 1-4 μm, and more interestingly, they show a perfect single-crystalline nature, which is not usual according to the crystal growth theories and may bring extra benefits to applications. Electrochemical tests show good performance of the material in both the capacity and cycling stability as cathode material in a model cell. 相似文献
7.
Study of the surface modification of LiNi1/3Co1/3Mn1/3O2 cathode material for lithium ion battery 总被引:1,自引:0,他引:1
A.M.A. HashemA.E. Abdel-Ghany A.E. EidJ. Trottier K. Zaghib A. MaugerC.M. Julien 《Journal of power sources》2011,196(20):8632-8637
The surface of LiNi1/3Co1/3Mn1/3O2 (LNMCO) particles has been studied for material synthesized at 900 °C by a two-step process from a mixture of LiOH·H2O and metal oxalate [(Ni1/3Co1/3Mn1/3)C2O4] obtained by co-precipitation. Samples have been characterized by X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), Raman scattering (RS) spectroscopy, and magnetic measurements. We have investigated the effect of the heat treatment of particles at 600 °C with organic substances such as sucrose and starch. HRTEM images and RS spectra indicate that the surface of particles has been modified. The annealing does not lead to any carbon coating but it leads to the crystallization of the thin disordered layer on the surface of LiNi1/3Co1/3Mn1/3O2. The beneficial effect has been tested on the electrochemical properties of the LiNi1/3Co1/3Mn1/3O2 cathode materials. The capacity at 10C-rate is enhanced by 20% for post-treated LNMCO particles at 600 °C for half-an-hour. 相似文献
8.
Xiao-Jian Guo Yi-Xiao LiMin Zheng Jian-Ming ZhengJie Li Zheng-Liang GongYong Yang 《Journal of power sources》2008
A series of cathode materials with molecular notation of xLi[Li1/3Mn2/3]O2·(1 − x)Li[Ni1/3Mn1/3Co1/3]O2 (0 ≤ x ≤ 0.9) were synthesized by combination of co-precipitation and solid state calcination method. The prepared materials were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques, and their electrochemical performances were investigated. The results showed that sample 0.6Li[Li1/3Mn2/3]O2·0.4Li[Ni1/3Mn1/3Co1/3]O2 (x = 0.6) delivers the highest capacity and shows good capacity-retention, which delivers a capacity ∼250 mAh g−1 between 2.0 and 4.8 V at 18 mA g−1. 相似文献
9.
LiNi1/3Co1/3Mn1/3O2 is prepared by a rheological phase method. Homogeneous precursor derived from this method is calcined at 800 °C for 20 h in air, which results in the impressive differences in the morphology properties and electrochemical behaviors of LiNi1/3Co1/3Mn1/3O2 in contrast to that obtained by a solid-state method. The microscopic structural features of LiNi1/3Co1/3Mn1/3O2 are investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD). The electrochemical properties of LiNi1/3Co1/3Mn1/3O2 are carried out by charge–discharge cycling test. All experiments show that the microscopic structural features and the morphology properties are deeply related with the electrochemical performances. The obtained results suggest that the rheological phase method may become an effective route to prepare LiNi1/3Co1/3Mn1/3O2 cathode materials for lithium battery. 相似文献
10.
Layer-structured Zr doped Li[Ni1/3Co1/3Mn1−x/3Zrx/3]O2 (0 ≤ x ≤ 0.05) were synthesized via slurry spray drying method. The powders were characterized by XRD, SEM and galvanostatic charge/discharge tests. The products remained single-phase within the range of 0 ≤ x ≤ 0.03. The charge and discharge cycling of the cells showed that Zr doping enhanced cycle life compared to the bare one, while did not cause the reduction of the discharge capacity of Li[Ni1/3Co1/3Mn1/3]O2. The unchanged peak shape in the differential capacity versus voltage curve suggested that the Zr had the effect to stabilize the structure during cycling. More interestingly, the rate capability was greatly improved. The sample with x = 0.01 presented a capacity of 160.2 mAh g−1 at current density of 640 mA g−1(4 C), corresponding to 92.4% of its capacity at 32 mA g−1(0.2 C). The favorable performance of the doped sample could be attributed to its increased lattice parameter. 相似文献
11.
Electrochemical effects of ALD surface modification on combustion synthesized LiNi1/3Mn1/3Co1/3O2 as a layered-cathode material 总被引:1,自引:0,他引:1
Leah A. Riley Sky Van AttaAndrew S. Cavanagh Yanfa YanSteven M. George Ping LiuAnne C. Dillon Se-Hee Lee 《Journal of power sources》2011,196(6):3317-3324
Combustion synthesized Li(Ni1/3Mn1/3Co1/3)O2 particles are coated with thin, conformal layers of Al2O3 by atomic layer deposition (ALD). XRD, Raman, and FTIR are used to confirm that no change to the bulk, local structure occurs after coating. Electrochemical impedance spectroscopy (EIS) results indicate that the surface of the Li(Ni1/3Mn1/3Co1/3)O2 are protected from dissolution and HF attack after only 4-layers, or ∼8.8 Å of alumina. Electrochemical performance at an upper cutoff of 4.5 V is greatly enhanced after the growth of Al2O3 surface film. Capacity retention is increased from 65% to 91% after 100 cycles at a rate of C/2 with the addition of only two atomic layers. Due to the conformal coating, the effects on Li(Ni1/3Mn1/3Co1/3)O2 overpotential and capacity are negligible below six ALD-layers. We propose that the use of ALD for coating on Li(Ni1/3Mn1/3Co1/3)O2 particles makes the material a stronger replacement candidate for LiCoO2 as a positive electrode in lithium ion batteries. 相似文献
12.
A modified Zr-coating process was introduced to improve the electrochemical performance of Li(Ni1/3Co1/3Mn1/3)O2. The ZrO2-coating was carried out on an intermediate, (Ni1/3Co1/3Mn1/3)(OH)2, rather than on Li(Ni1/3Co1/3Mn1/3)O2. After a heat treatment process, one part of the Zr covered the surface of Li(Ni1/3Co1/3Mn1/3)O2 in the form of a Li2ZrO3 coating layer, and the other part diffused into the crystal lattice of Li(Ni1/3Co1/3Mn1/3)O2. A decreasing gradient distribution in the concentration of Zr was detected from the surface to the bulk of Li(Ni1/3Co1/3Mn1/3)O2 by X-ray photoelectron spectra (XPS). Electrochemical tests indicated that the 1% (Zr/Ni + Co + Mn) ZrO2-modified Li(Ni1/3Co1/3Mn1/3)O2 prepared by this process showed better cyclability and rate capability than bare Li(Ni1/3Co1/3Mn1/3)O2. The result can be ascribed to the special effect of Zr in ZrO2-modified Li(Ni1/3Co1/3Mn1/3)O2. The surface coating layer of Li2ZrO3 improved the cycle performance, while the incorporation of Zr in the crystal lattice of Li(Ni1/3Co1/3Mn1/3)O2 modified the rate capability by increasing the lattice parameters. Electrochemical impedance spectra (EIS) results showed that the increase of charge transfer resistance during cycling was suppressed significantly by ZrO2 modification. 相似文献
13.
The spherical Li[Ni1/3Co1/3Mn1/3]O2 powders with appropriate porosity, small particle size and good particle size distribution were successfully prepared by a slurry spray drying method. The Li[Ni1/3Co1/3Mn1/3]O2 powders were characterized by XRD, SEM, ICP, BET, EIS and galvanostatic charge/discharge testing. The material calcined at 950 °C had the best electrochemical performance. Its initial discharge capacity was 188.9 mAh g−1 at the discharge rate of 0.2 C (32 mA g−1), and retained 91.4% of the capacity on going from 0.2 to 4 C rate. From the EIS result, it was found that the favorable electrochemical performance of the Li[Ni1/3Co1/3Mn1/3]O2 cathode material was primarily attributed to the particular morphology formed by the spray drying process which was favorable for the charge transfer during the deintercalation and intercalation cycling. 相似文献
14.
The low-heating solid-state method has been adopted to synthesize LiNi1/3Co1/3Mn1/3O2 materials. The final product, with homogeneous phase and smooth crystals indicated by XRD and SEM results, can be synthesized at 700 °C, much lower than the synthesis temperatures of co-precipitation method. The reaction process and microstructure of precursor has been investigated by IR spectrum. By comparative studies with the mixture of CH3COOLi and (Ni, Co, Mn)(C2O4), it is testified that the precursor is homogeneous, rather than a mixture. The decomposition process and the reaction energy have been studied to investigate the reaction mechanism of the precursor when heated at high temperature. The as-synthesized LiNi1/3Co1/3Mn1/3O2 exhibits excellent electrochemical properties, exhibiting initial specific capacity of 167 mAh g−1 with stable cyclic performance. 相似文献
15.
Lithium non-stoichiometric Li[Lix(Ni1/3Co1/3Mn1/3)1−x]O2 materials (0 ≤ x ≤ 0.17) were synthesized using a spray drying method. The electrochemical properties and structural stabilities of the synthesized materials were investigated. The synthesized materials exhibited a hexagonal structure in all the x-value and the lattice parameters of the materials were gradually decreased with increasing x-value due to an increasing amount of Ni3+ ions for charge compensation. The capacity retention ability and rate capability of the stoichiometric Li(Ni1/3Co1/3Mn1/3)O2 material were improved by increasing x-value, the so-called overlithiation. We found that the overlithiated materials could keep more structural integrity than the stoichiometric one during electrochemical cyclings, which could be one of reasons for a better electrochemical properties of the overlithiated materials. 相似文献
16.
The layered LiNi1/3Mn1/3Co1/3O2 materials with good crystalline are synthesized by a novel method of hydrothermal method followed by a short calcination process. The crystalline structure and morphology of the synthesized materials are characterized by XRD, SEM. Their electrochemical performances are evaluated by CV, EIS and galvonostatic charge/discharge tests. The material synthesized at 850 °C for 6 h shows the highest initial discharge capacity of 187.7 mAh g−1 at 20 mA g−1. And the capacity retention of 97.9% is maintained at the end of 40 cycles at 1.0 C. CV test reveals almost no shift of anodic and cathodic peaks after first cycle, which indicates good reversible deintercalation and intercalation of Li+ ions. 相似文献
17.
Yan-Bing He Zhi-Yuan Tang Quan-Sheng Song Hui Xie Quan-Hong Yang Yuan-Gang Liu Guo-Wei Ling 《Journal of power sources》2008
The commercial 18650 Li(Ni1/3Co1/3Mn1/3)O2/graphite high power batteries were prepared and their electrochemical performance at temperatures of 25 and 50 °C was extensively investigated. The results showed that the charge-transfer resistance (Rct) and solid electrolyte interface resistance (Rsei) of the high power batteries at 25 °C decreased as states of charge (SOC) increased from 0 to 60%, whereas Rct and Rsei increased as SOC increased from 60 to 100%. The discharge plateau voltage of batteries reduced greatly with the increase in discharge rate at both 25 and 50 °C. The high power batteries could be discharged at a very wide current range to deliver most of their capacity and also showed excellent power cycling performance with discharge rate of as high as 10 C at 25 °C. The elevated working temperature did not influence the battery discharge capacity and cycling performance at lower discharge rates (e.g. 0.5, 1, and 5 C), while it resulted in lower discharge capacity at higher discharge rates (e.g. 10 and 15 C) and bad cycling performance at discharge rate of 10 C. The batteries also exhibited excellent cycle performance at charge rate of as high as 8 C and discharge rate of 10 C. 相似文献
18.
The compatibility between dimethyl methylphosphonate (DMMP)-based electrolyte of 1 M LiPF6/EC + DMC + DMMP (1:1:2 wt.) and spinel materials Li4Ti5O12 and LiNi0.5Mn1.5O4 was reviewed, respectively. The cell performance and impedance of 3-V LiNi0.5Mn1.5O4/Li4Ti5O12 lithium-ion cell with the DMMP-based nonflammable electrolyte was compared with the baseline electrolyte of 1 M LiPF6/EC + DMC (1:1 wt.). The nonflammable DMMP-based electrolyte exhibited good compatibility with spinel Li4Ti5O12 anode and high-voltage LiNi0.5Mn1.5O4 cathode, and acceptable cycling performance in the LiNi0.5Mn1.5O4/Li4Ti5O12 full-cell, except for the higher impedance than that in the baseline electrolyte. All of the results disclosed that the 3 V LiNi0.5Mn1.5O4/Li4Ti5O12 lithium-ion battery was a promising choice for the nonflammable DMMP-based electrolyte. 相似文献
19.
In this work structural and transport properties of layered Li1+x(Mn1/3Co1/3Ni1/3)1−xO2 oxides (x = 0; 0.03; 0.06) prepared by a “soft chemistry” method are presented. The excessive lithium was found to significantly improve transport properties of the materials, a corresponding linear decrease of the unit cell parameters was observed. The electrical conductivity of Li1.03(Mn1/3Co1/3Ni1/3)0.97O2 composition was high enough to use this material in a form of a pellet, without any additives, in lithium batteries and characterize structural and transport properties of deintercalated Li1.03−y(Mn1/3Co1/3Ni1/3)0.97O2 compounds. For deintercalated samples a linear increase of the lattice parameter c together with a linear decrease of the parameter a with the increasing deintercalation degree occurred, but only up to 0.4-0.5 mol of extracted lithium. Further deintercalation showed a reversal of the trend. Electrical conductivity measurements performed of Li1.03−y(Mn1/3Co1/3Ni1/3)0.97O2 samples (y = 0.1; 0.3; 0.5; 0.6) showed an ongoing improvement, almost two orders of magnitude, in relation to the starting composition. Additionally, OCV measurements, discharge characteristics and lithium diffusion coefficient measurements were performed for Li/Li+/Li1.03−y(Mn1/3Co1/3Ni1/3)0.97O2 cells. 相似文献
20.
A (Ni1/3Co1/3Mn1/3)CO3 precursor with an uniform, spherical morphology was prepared by coprecipitation using a continuously stirred tank reactor method. The as-prepared spherical (Ni1/3Co1/3Mn1/3)CO3 precursor served to produce dense, spherical Li1+x(Ni1/3Co1/3Mn1/3)1−xO2 (0 ≤ x ≤ 0.15) cathode materials. These Li-rich cathodes were also prepared by a second synthesis route that involved the use of an M3O4 (M = Ni1/3Co1/3Mn1/3) spinel compound, itself obtained from the carbonate (Ni1/3Co1/3Mn1/3)CO3 precursor. In both cases, the final Li1+x(Ni1/3Co1/3Mn1/3)1−xO2 products were highly uniform, having a narrow particle size distribution (10-μm average particle size) as a result of the homogeneity and spherical morphology of the starting mixed-metal carbonate precursor. The rate capability of the Li1+x(Ni1/3Co1/3Mn1/3)1−xO2 electrode materials, which was significantly improved with increased lithium content, was found to be better in the case of the denser materials made from the spinel precursor compound. This result suggests that spherical morphology, high density, and increased lithium content were key factors in enabling the high rate capabilities, and hence the power performances, of the Li-rich Li1+x(Ni1/3Co1/3Mn1/3)1−xO2 cathodes. 相似文献