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1.
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
2.
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
3.
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
4.
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
5.
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
6.
LiFePO4/C composite cathode materials were synthesized by carbothermal reduction method using inexpensive FePO4 as raw materials and glucose as conductive additive and reducing agent. The precursor of LiFePO4/C was characterized by differential thermal analysis and thermogravimetry. The microstructure and morphology of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and particle size analysis. Cyclic voltammetry (CV) and charge/discharge cycling performance were used to characterize their electrochemical properties. The results showed that the LiFePO4/C composite synthesized at 650 °C for 9 h exhibited the most homogeneous particle size distribution. Residual carbon during processing was coated on LiFePO4, resulting in the enhancement of the material's electronic properties. Electrochemical measurements showed that the discharge capacity first increased and then decreased with the increase of synthesis temperature. The optimal sample synthesized at 650 °C for 9 h exhibited a highest initial discharge capacity of 151.2 mA h g−1 at 0.2 C rate and 144.1 mA h g−1 at 1 C rate with satisfactory capacity retention rate. 相似文献
7.
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
8.
Yan Feng 《Journal of power sources》2009,192(2):708-713
LiV3O8, synthesized from V2O5 and LiOH, by heating of a suspension of V2O5 in a LiOH solution at a low-temperature (100-200 °C), exhibits a high discharge capacity and excellent cyclic stability at a high current density as a cathode material of lithium-ion battery. The charge-discharge curve shows a maximum discharge capacity of 228.6 mAh g−1 at a current density of 150 mA g−1 (0.5 C rate) and the 100 cycles discharge capacity remains 215 mAh g−1. X-ray diffraction indicates the low degree of crystallinity and expanding of inter-plane distance of the LiV3O8 phase, and scanning electronic microscopy reveals the formation of nano-domain structures in the products, which account for the enhanced electrochemical performance. In contrast, the LiV3O8 phase formed at a higher temperature (300 °C) consists of well-developed crystal phases, and coherently, results in a distinct reduction of discharge capacity with cycle numbers. Thus, an enhanced electrochemical performance has been achieved for LiV3O8 by the soft chemical method via a low-temperature heating process. 相似文献
9.
Li-ming Li Hua-jun GuoXin-hai Li Zhi-xing WangWen-jie Peng Kai-xiong XiangXuan Cao 《Journal of power sources》2009
Li2FeSiO4/C cathodes were synthesized by combination of wet-process method and solid-state reaction at high temperature, and effects of roasting temperature and modification on properties of the Li2FeSiO4/C cathode were investigated. The XRD patterns of the Li2FeSiO4/C samples indicate that all the samples are of good crystallinity, and a little Fe3O4 impurity was observed in them. The primary particle size rises as the roasting temperature increases from 600 to 750 °C. The Li2FeSiO4/C sample synthesized at 650 °C has good electrochemical performances with an initial discharge capacity of 144.9 mAh g−1 and the discharge capacity remains 136.5 mAh g−1 after 10 cycles. The performance of Li2FeSiO4/C cathode is further improved by modification of Ni substitution. The Li2Fe0.9Ni0.1SiO4/C composite cathode has an initial discharge capacity of 160.1 mAh g−1, and the discharge capacity remains 153.9 mAh g−1 after 10 cycles. The diffusion coefficient of lithium in Li2FeSiO4/C is 1.38 × 10−12 cm2 s−1 while that in Li2Fe0.9Ni0.1SiO4/C reaches 3.34 × 10−12 cm2 s−1. 相似文献
10.
Nanosized Ni3(Fe(CN)6)2(H2O) was prepared by a simple co-precipitation method. The electrochemical properties of the sample as the electrode material for supercapacitor were studied by cyclic voltammetry (CV), constant charge/discharge tests and electrochemical impedance spectroscopy (EIS). A specific capacitance of 574.7 F g−1 was obtained at the current density of 0.2 A g−1 in the potential range from 0.3 V to 0.6 V in 1 M KNO3 electrolyte. Approximately 87.46% of specific discharge capacitance was remained at the current density of 1.4 A g−1 after 1000 cycles. 相似文献
11.
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
12.
Li LiYaping Wang Yijing Wang Yan HanFangyuan Qiu Guang LiuChao Yan Dawei SongLifang Jiao Huatang Yuan 《Journal of power sources》2011,196(24):10758-10761
A potential negative electrode material (mesoporous nano-Co3O4) is synthesized via a simple thermal decomposition of precursor Co(OH)2 hexagonal nanosheets in the air. The structure and morphology of the samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It is found that the nano-Co3O4 is present in mesoporous hexagonal nanoparticles. The average size of holes is about 5-15 nm. The electrochemical performances of mesoporous nano-Co3O4 as the active starting negative electrode material for alkaline secondary battery are investigated by galvanostatic charge-discharge and cyclic voltammetry (CV) technique. The results demonstrate that the prepared mesoporous nano-Co3O4 electrode displays excellent electrochemical performance. The discharge capacity of the mesoporous nano-Co3O4 electrode can reach 436.5 mAh g−1 and retain about 351.5 mAh g−1 after 100 cycles at discharge current of 100 mA g−1. A properly electrochemical reaction mechanism of mesoporous nano-Co3O4 electrode is also constructed in detail. 相似文献
13.
A nanocrystalline Li4Ti5O12-TiO2 duplex phase has been synthesized by a simple basic molten salt process (BMSP) using an eutectic mixture of LiNO3-LiOH-Li2O2 at 400-500 °C. The microstructure and morphology of the Li4Ti5O12-TiO2 product are characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The sample prepared by heat-treating at 300 °C for 3 h (S-1) reveals dense agglomerates of ultra-fine nanocrystalline Li4Ti5O12; with heat treatment at 400 °C for 3 h (S-2), there is a duplex crystallite size (fine < 10 nm, and coarse > 20 nm) of Li4Ti5O12-TiO2; at 500 °C for 3 h (S-3), a much coarser and less-dense distribution of lithium titanate (crystallite size ∼15-30 nm) is observed. According to the results of electrochemical testing, the S-2 sample shows initial discharge capacities of 193 mAh g−1 at 0.2 C, 168 mAh g−1 at 0.5 C, 146 mAh g−1 at 1 C, 135 mAh g−1 at 2 C, and 117 mAh g−1 at 5 C. After 100 cycles, the discharge capacity is 138 mAh g−1 at 1 C with a capacity retention of 95%. The S-2 sample yields the best electrochemical performance in terms of charge-discharge capacity and rate capability compared with other samples. Its superior electrochemical performance can be mainly attributed to the duplex crystallite structure, composed of fine (<10 nm) and coarse (>20) nm nanoparticles, where lithium ions can be stored within the grain boundary interfaces between the spinel Li4Ti5O12 and the anatase TiO2. 相似文献
14.
Hee-Cheol Kang Dae-Kyoo Jun Bo Jin En Mei Jin Kyung-Hee Park Hal-Bon Gu Ki-Won Kim 《Journal of power sources》2008
Olivine-type LiFePO4 cathode materials were synthesized by a solid-state reaction method and ball-milling. The ball-milling time, heating time and heating temperature are optimized. A heating temperature higher than 700 °C resulted in the appearance of impurity phase Fe2P and growth of large particle, which was shown by high resolution X-ray diffraction and field emission scanning electron microscopy. The impurity phase Fe2P exhibited a considerable capacity loss at the 1st cycle and a gradual increase in discharge capacity upon cycling. Moreover, it exhibited an excellent high-rate capacity of 104 mAh g−1 at 3 C in spite of the large particle size. The optimum synthesis conditions for LiFePO4 were ball-milling for 24 h and heat-treatment at 600 °C for 3 h. LiFePO4/Li cells showed an enhanced cycling performance and a high discharge capacity of 160 mAh g−1 at 0.1 C. 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 electrolytic deposition of Co3O4 thin films on stainless steel was conducted in Co(NO3)2 aqueous solution for anodes in lithium-ion thin film batteries. Three major electrochemical reactions during the deposition were discussed. The coated specimens and the coating films carried out at −1.0 V (saturated KCl Ag/AgCl) were subjected to annealing treatments and further characterized by XRD, TGA/DTA, FE-SEM, Raman spectroscopy, cyclic voltammetry (CV) and discharge/charge cyclic tests. The as-coated film was β-Co(OH)2, condensed into CoO and subsequently oxidized into nano-sized Co3O4 particles. The nano-sized Co3O4, CoO, Li2O and Co particles revealed their own characteristics different from micro-sized ones, such as more interfacial effects on chemical bonding and crystallinity. The initial maximum capacity of Co3O4 coated specimen was 1930 mAh g−1 which much more than its theoretical value 890 mAh g−1, since the nano-sized particles offered more interfacial bondings for extra sites of Li+ insertion. However, a large ratio of them was trapped, resulting in a great part of irreversible capacity during the first charging. Still, it revealed a capacity 500 mAh g−1 after 50 discharged-charged cycles. 相似文献
17.
LiFePO4 as a cathode material for rechargeable lithium batteries was prepared by hydrothermal process at 170 °C under inert atmosphere. The starting materials were LiOH, FeSO4, and (NH4)2HPO4. The particle size of the obtained LiFePO4 was 0.5 μm. The electrochemical properties of LiFePO4 were characterized in a mixed solvent of ethylene carbonate and diethyl carbonate (1:1 in volume) containing 1.0 mol dm−3 LiClO4. The hydrothermally synthesized LiFePO4 exhibited a discharge capacity of 130 mA h g−1, which was smaller than theoretical capacity (170 mA h g−1). The annealing of LiFePO4 at 400 °C in argon atmosphere was effective in increasing the discharge capacity. The discharge capacity of the annealed LiFePO4 was 150 mA h g−1. 相似文献
18.
Phospho-olivine LiFePO4 cathode materials were prepared by hydrothermal reaction at 150 °C. Carbon black was added to enhance the electrical conductivity of LiFePO4. LiFePO4-C powders (0, 3, 5 and 10 wt.%) were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). LiFePO4-C/solid polymer electrolyte (SPE)/Li cells were characterized electrochemically by charge/discharge experiments at a constant current density of 0.1 mA cm−2 in a range between 2.5 and 4.3 V vs. Li/Li+, cyclic voltammetry (CV) and ac impedance spectroscopy. The results showed that initial discharge capacity of LiFePO4 was 104 mAh g−1. The discharge capacity of LiFePO4-C/SPE/Li cell with 5 wt.% carbon black was 128 mAh g−1 at the first cycle and 127 mAh g−1 after 30 cycles, respectively. It was demonstrated that cycling performance of LiFePO4-C/SPE/Li cells was better than that of LiFePO4/SPE/Li cells. 相似文献
19.
A simple method has been employed to prepare pillared layered Li1−2xCaxCoO2 cathode materials by cationic exchange under hydrothermal conditions. The synthesized materials were characterized by means of X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), field emission scanning electron microscope (FE-SEM) and galvanostatic charge–discharge cycling. The XRD data of the products show that they are single phases and retain the layered α-NaFeO2 type structure. The FE-SEM images of the materials prepared by hydrothermal method show uniform small particles, and the particle size of the materials is about 200 nm. The initial discharge specific capacities of layered LiCoO2 and pillared layered Li0.946Ca0.027CoO2 cathode materials calcined at 800 °C for 5 h within the potential range of 3.0–4.3 V (vs. Li+/Li) are 144.6 and 142.3 mAh g−1, respectively, and both materials retain good charge–discharge cycling performance. However, with increasing upper cutoff voltage, the pillar effect of Ca2+ in Li1−2xCaxCoO2 becomes more significant. The pillared layered Li0.946Ca0.027CoO2 has a higher capacity with an initial discharge specific capacity of 177.9 and 215.8 mAh g−1 within the potential range of 3.0–4.5 and 4.7 V (vs. Li+/Li), respectively, and retains good charge–discharge cycling performance. 相似文献
20.
Single-phase lithium nickel manganese oxide, LiNi0.5Mn0.5O2, was successfully synthesized from a solid solution of Ni1.5Mn1.5O4 that was prepared by means of the solid reaction between Mn(CH3COO)2·4H2O and Ni(CH3COO)2·4H2O. XRD pattern shows that the product is well crystallized with a high degree of Li–M (Ni, Mn) order in their respective layers, and no diffraction peak of Li2MnO3 can be detected. Electrochemical performance of as-prepared LiNi0.5Mn0.5O2 was examined in the test battery by charge–discharge cycling with different rate, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The cycling behavior between 2.5 and 4.4 V at a current rate of 21.7 mA g−1 shows a reversible capacity of about 190 mAh g−1 with little capacity loss after 100 cycles. High-rate capability test shows that even at a rate of 6C, stable capacity about 120 mAh g−1 is retained. Cyclic voltammetry (CV) profile shows that the cathode material has better electrochemical reversibility. EIS analysis indicates that the resistance of charge transfer (Rct) is small in fully charged state at 4.4 V and fully discharged state at 2.5 V versus Li+/Li. The favorable electrochemical performance was primarily attributed to regular and stable crystal structure with little intra-layer disordering. 相似文献