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1.
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
2.
B.-C. Park H.-B. Kim S.-T. Myung K. Amine I. Belharouak S.-M. Lee Y.-K. Sun 《Journal of power sources》2008
The particle surface of Li[Ni1/3Co1/3Mn1/3]O2 was modified by AlF3 as a new coating material to improve the electrochemical properties in the high cutoff voltage of 4.5 V. The AlF3-coated Li[Ni1/3Co1/3Mn1/3]O2 showed no difference in the bulk structure compared with the pristine one and the uniform AlF3 coating layers whose thickness is of about 10 nm covered Li[Ni1/3Co1/3Mn1/3]O2 particles, as confirmed by a transmission electron microscopy. The AlF3 coating on Li[Ni1/3Co1/3Mn1/3]O2 particles improved the overall electrochemical properties such as the cyclability, rate capability and thermal stability compared with those of the pristine Li[Ni1/3Co1/3Mn1/3]O2. Such enhancements were attributed to the presence of the stable AlF3 layer which acts as the interfacial stabilizer on the surface of Li[Ni1/3Co1/3Mn1/3]O2. 相似文献
3.
Al2O3-modified Li(Ni1/3Co1/3Mn1/3)O2 is synthesized by a modified Al2O3 coating process. The Al2O3 coating is carried out on an intermediate, (Ni1/3Co1/3Mn1/3)(OH)2, rather than on Li(Ni1/3Co1/3Mn1/3)O2. As a comparison, Al2O3-coated Li(Ni1/3Co1/3Mn1/3)O2 also is prepared by traditional Al2O3 coating process. The effects of Al2O3 coating and Al2O3 modification on structure and electrochemical performance are investigated and compared. Electrochemical tests indicate that cycle performance and rate capability of Li(Ni1/3Co1/3Mn1/3)O2 are enhanced by Al2O3 modification without capacity loss. Al2O3 coating can also enhance the cycle performance but cause evident capacity loss and decline of rate capability. The effect of Al2O3 coating and Al2O3 modification on kinetics of lithium-ion transfer reaction at the interface of electrode/electrolyte is investigated via electrochemical impedance spectra (EIS). The result support that the Al2O3 modification increase Li+ diffused coefficient and decrease the activation energy of Li+ transfer reaction but the traditional Al2O3 coating lead to depression of Li+ diffused coefficient and increase of activation energy. 相似文献
4.
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
5.
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
6.
Structural changes and their relationship with thermal stability of charged Li0.33Ni1/3Co1/3Mn1/3O2 cathode samples have been studied using time-resolved X-ray diffraction (TR-XRD) in a wide temperature from 25 to 600 °C with and without the presence of electrolyte in comparison with Li0.27Ni0.8Co0.15Al0.05O2 cathodes. Unique phase transition behavior during heating is found for the Li0.33Ni1/3Co1/3Mn1/3O2 cathode samples: when no electrolyte is present, the initial layered structure changes first to a LiM2O4-type spinel, and then to a M3O4-type spinel and remains in this structure up to 600 °C. For the Li0.33Ni1/3Co1/3Mn1/3O2 cathode sample with electrolyte, additional phase transition from the M3O4-type spinel to the MO-type rock salt phase takes place from about 400 to 441 °C together with the formation of metallic phase at about 460 °C. The major difference between this type of phase transitions and that for Li0.27Ni0.8Co0.15Al0.05O2 in the presence of electrolyte is the delayed phase transition from the spinel-type to the rock salt-type phase by stretching the temperature range of spinel phases from about 20 to 140 °C. This unique behavior is considered as the key factor of the better thermal stability of the Li1−xNi1/3Co1/3Mn1/3O2 cathode materials. 相似文献
7.
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
8.
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
9.
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
10.
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
11.
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
12.
Li1+x(Ni1/3Mn1/3Co1/3)1−xO2 layered materials were synthesized by the co-precipitation method with different Li/M molar ratios (M = Ni + Mn + Co). Elemental titration evaluated by inductively coupled plasma spectrometry (ICP), structural properties studied by X-ray diffraction (XRD), Rietveld analysis of XRD data, scanning electron microscopy (SEM) and magnetic measurements carried out by superconducting quantum interference devices (SQUID) showed the well-defined α-NaFeO2 structure with cationic distribution close to the nominal formula. The Li/Ni cation mixing on the 3b Wyckoff site of the interlayer space was consistent with the structural model [Li1−yNiy]3b[Lix+yNi(1−x)/3−yMn(1−x)/3Co(1−x)/3]3aO2 (x = 0.02, 0.04) and was very small. Both Rietveld refinements and magnetic measurements revealed a concentration of Ni2+-3b ions lower than 2%; moreover, for the optimized sample synthesized at Li/M = 1.10, only 1.43% of nickel ions were located into the Li sublattice. Electrochemical properties were investigated by galvanostatic charge-discharge cycling. Data obtained with Li1+x(Ni1/3Mn1/3Co1/3)1−xO2 reflected the high degree of sample optimization. An initial discharge capacity of 150 mAh g−1 was delivered at 1 C-rate in the cut-off voltage of 3.0-4.3 V. More than 95% of its initial capacity was retained after 30 cycles at 1 C-rate. Finally, it is demonstrated that a cation mixing below 2% is considered as the threshold for which the electrochemical performance does not change for Li1+x(Ni1/3Mn1/3Co1/3)1−xO2. 相似文献
13.
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
14.
Ki-Soo Lee Seung-Taek Myung Dong-Won KimYang-Kook Sun 《Journal of power sources》2011,196(16):6974-6977
Surface modifications of electrode materials can improve the electrochemical and thermal properties of cathodes for use in lithium batteries. In this study, AlF3-coated LiCoO2 and AlF3-coated Li[Ni1/3Co1/3Mn1/3]O2 cathode materials are blended, as both have the same crystal structure and exhibit similar electrochemical properties. The composite electrodes exhibit high discharge capacities of 180-188 mAh g−1 in a voltage range of 3.0-4.5 V at room temperature. The capacity retention of the composite electrode is greater than 95% of the initial capacity after 50 cycles. The thermal stability of these composite electrodes is greatly improved because of the superior thermal stability of AlF3-coated Li[Ni1/3Co1/3Mn1/3]O2. The blended AlF3-coated LiCoO2 and AlF3-coated Li[Ni1/3Co1/3Mn1/3]O2 electrode shows two exothermic peaks, one at 227 °C from AlF3-coated LiCoO2 and another at 277 °C from AlF3-coated Li[Ni1/3Co1/3Mn1/3]O2, accompanied by significantly reduced exothermic heat generation. 相似文献
15.
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
16.
Amorphous LiCo1/3Mn1/3Ni1/3O2 thin films were deposited on the NASICON-type Li-ion conducting glass ceramics, Li1+x+yAlxTi2−xSiyP3−yO12 (LATSP), by radio frequency (RF) magnetron sputtering below 130 °C. The amorphous films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The Li/PEO18-Li(CF3SO2)2N/LATSP/LiCo1/3Mn1/3Ni1/3O2/Au all-solid-state cells were fabricated to investigate the electrochemical performance of the amorphous films. It was found that the low-temperature deposited amorphous cathode film shows a high discharge voltage and a high discharge capacity of around 130 mAh g−1. 相似文献
17.
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
18.
A novel method to improve the cycling performance of LiCo1/3Ni1/3Mn1/3O2 in lithium-ion batteries by TiO2-coating with an in situ dipping and hydrolyzing method was presented in this work. The microstructure of the TiO2-coated LiCo1/3Ni1/3Mn1/3O2 was characterized by XRD, SEM and TEM, and their electrochemical performances were evaluated by EIS and galvonostatic charge-discharge test. SEM and TEM images show that the TiO2 are pasted on the surface of the LiCo1/3Ni1/3Mn1/3O2 with nano-size. The XRD patterns indicate that the crystal structure of the TiO2-coated LiCo1/3Ni1/3Mn1/3O2 shows no obvious change compares with the bare material. The TiO2-coated LiCo1/3Ni1/3Mn1/3O2 possesses improved cycle performance and rate capability. The capacity retention of 1.0 wt.% TiO2-coated material is more than 99.0% after 12 cycles at 3.0 C while that of the bare sample is only 86.6%. The capacity of coated material at 5.0 C remains 66.0% of the capacity at 0.2 C, while that of the bare LiCo1/3Ni1/3Mn1/3O2 is only 31.5%. 相似文献
19.
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
20.
In this study, nano-crystalline LiCoO2 was coated onto the surface of Li1.05Ni0.35Co0.25Mn0.4O2 powders via sol–gel method. The influence of the coating on the electrochemical behavior of Li1.05Ni0.35Co0.25Mn0.4O2 is discussed. The surface morphology was characterized by transmission electron microscopy (TEM). Nano-crystallized LiCoO2 was clearly observed on the surfaces of Li1.05Ni0.35Co0.25Mn0.4O2. The phase and structural changes of the cathode materials before and after coating were revealed by X-ray diffraction spectroscopy (XRD). It was found that LiCoO2 coated Li1.05Ni0.35Co0.25Mn0.4O2 cathode material exhibited distinct surface morphology and lattice constants. Cyclic voltammetry (2.8–4.6 V versus Li/Li+) shows that the characteristic voltage transitions on cycling exhibited by the uncoated material are suppressed by the 7 wt.% LiCoO2 coating. This behavior implies that LiCoO2 inhibits structural change of Li1.05Ni0.35Co0.25Mn0.4O2 or reaction with the electrolyte on cycling. In addition, the LiCoO2 coating on Li1.05Ni0.35Co0.25Mn0.4O2 significantly improves the rate capability over the range 0.1–4.0C. Comparative data for the coated and uncoated materials are presented and discussed. 相似文献