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1.
Br-doped Li4Ti5O12 in the form of Li4Ti5O12−xBrx (0 ≤ x ≤ 0.3) compounds were successfully synthesized via solid state reaction. The structure and electrochemical properties of the spinel Li4Ti5O12−xBrx (0 ≤ x ≤ 0.3) materials were investigated. The Li4Ti5O12−xBrx (x = 0.2) presents the best discharge capacity among all the samples, and shows better reversibility and higher cyclic stability compared with pristine Li4Ti5O12, especially at high current rates. When the discharge rate was 0.5 C, the Li4Ti5O12−xBrx (x = 0.2) sample presented the excellent discharge capacity of 172 mAh g−1, which was very close to its theoretical capacity (175 mAh g−1), while that of the pristine Li4Ti5O12 was 123.2 mAh g−1 only. 相似文献
2.
Al-doped Li4Ti5O12 in the form of Li4−xAlxTi5O12 (x = 0, 0.05, 0.1 and 0.2) was synthesized via solid state reaction in an Ar-flowing atmosphere. Al-doping does not change the phase composition and particle morphology, but easily results in the lattice distortion and thus the poor crystallinity of Li4Ti5O12. Al-doping decreases the specific capacity of Li4Ti5O12, while improves remarkably its cycling stability at high charge/discharge rate. The substitution of Al for Li site can enhance the electronic conductivity of Li4Ti5O12 via the generation of mixing Ti4+/Ti3+, whereas impede the Li-ion diffusion in the lattice. Excessive Al causes large electrode polarization due to the lower Li-ion conductivity, and thus leads to low specific capacity at high current densities. Li3.9Al0.1Ti5O12 exhibits a relatively high specific capacity and an excellent cycling stability. 相似文献
3.
Zhenwei Zhang Liyun Cao Jianfeng Huang Dunqiang Wang Jianpeng Wu Yingjun Cai 《Ceramics International》2013
Lithium titanate (Li4Ti5O12) microsphere has been successfully synthesized by a hydrothermal method. X-ray diffraction (XRD) and scanning electron microscope (SEM) are used to characterize the structure and morphology of the prepared Li4Ti5O12 crystallites. The results show that the as-synthesized powders exhibit outstanding rate capacities and excellent cycling performance. The first discharge capacity at 0.1 C is 172.5 mAh g−1, which is close to the theoretical capacity of 175 mAh/g. After 50 cycles, the efficiency of the synthesized Li4Ti5O12 still retains up to 92.8% at 0.1 C and 95.2% at 0.5 C of its initial value, which present a promising applications as anode materials for lithium ion batteries in hybrid and plug-in hybrid electric vehicles. 相似文献
4.
CaCu3Ti4O12 nano-sized powders were successfully prepared by sol-gel technique and calcination at 600-900 °C. The thermal decomposition process, phase structures and morphology of synthesized powders were characterized by IR, DSC-TG, XRD, TEM, respectively. It was found that the main weight-loss and decomposition of precursors occurred below 450 °C and the complex perovskite phase appeared when the calcination temperature was higher than 700 °C. Using above synthesized powders as starting materials, CCTO-based ceramics with excellent dielectric properties (?25 = 5.9 × 104, tan δ = 0.06 at 1.0 kHz) were prepared by sintering at 1125 °C. According to the results, a conduction mechanism was proposed to explain the origin of giant dielectric constant in CCTO system. 相似文献
5.
Kaoru Dokko Jun-ichi Sugaya Hirokazu Munakata Kiyoshi Kanamura 《Electrochimica acta》2005,51(5):966-971
Fabrications of micro-dot electrodes of LiCoO2 and Li4Ti5O12 on Au substrates were demonstrated using a sol-gel process combined with a micro-injection technology. A typical size of prepared dots was about 100 μm in diameter, and the dot population on the substrate was 2400 dots cm−2. The prepared LiCoO2 and Li4Ti5O12 micro-dot electrodes were characterized with scanning electron microscopy, X-ray diffraction, micro-Raman spectroscopy, and cyclic voltammetry. The prepared LiCoO2 and Li4Ti5O12 micro-dot electrodes were evaluated in an organic electrolyte as cathode and anode for lithium micro-battery, respectively. The LiCoO2 micro-dot electrode exhibited reversible electrochemical behavior in a potential range from 3.8 to 4.2 V versus Li/Li+, and the Li4Ti5O12 micro-dot electrode showed sharp redox peaks at 1.5 V. 相似文献
6.
Porous (P-) and dense (D-) lithium titanate (Li4Ti5O12) powders as an anode material for lithium-ion batteries have been synthesized by spray drying followed by solid-state calcination. Electrochemical testing results showed that the discharge capacities of P-Li4Ti5O12 are 144 mAh/g, 128 mAh/g and 73 mAh/g at the discharging rate of 2C, 5C and 20C, respectively (cut-off voltages: 0.5-2.5 V). The corresponding values for D-Li4Ti5O12 are 108 mAh/g, 25 mAh/g and 17 mAh/g. The higher capacity of the P-Li4Ti5O12 at high charge/discharge rates was attributed to the shorter transport path of Li ions and higher electronic conductivity in the P-Li4Ti5O12 as a result of its smaller primary particle size and higher surface area compared with those of the D-Li4Ti5O12. 相似文献
7.
Hierarchical layered hydrous lithium titanate and Li4Ti5O12 microspheres assembled by nanosheets have been successfully synthesized via a hydrothermal process and subsequent thermal treatment. The electrochemical properties of the two samples have been investigated by galvanostatic methods. The former, with the obvious layered structure and a large surface area, delivers a reversible capacity of 180 mA h g−1 after 200 cycles at 200 mA g−1. As for Li4Ti5O12, with the intriguing and unique sawtooth-like morphology, it presents exceptional high rate performance and excellent cycling stability. Up to 132 mA h g−1 is obtained after 200 cycles at 10,000 mA g−1 (57 C), proving itself promising for high-rate applications. 相似文献
8.
Present paper describes electrochemical performance of the all solid-state lithium polymer battery (LBP) using spinel-type Li4/3Ti5/3O4 which has been known as the potential candidate of anode materials.The assembled LPB with Li|solid polymer electrolyte(SPE)|Li4/3Ti5/3O4 construction showed stable charge-discharge cycles more than 300 times at 1 C condition. On the other hand, strong charge-discharge rate dependence for the specific capacity and initial capacity loss was indicated. Such a poor rate performance stemmed from low diffusivity of Li+ ion in the by-products produced by the decomposition of SPE components at the SPE|Li4/3Ti5/3O4 interface. 相似文献
9.
S.Y. Yin L. Song X.Y. Wang M.F. Zhang K.L. Zhang Y.X. Zhang 《Electrochimica acta》2009,54(24):5629-5633
Using lithium acetate dihydrate and tetra-n-butyl titanate as the raw materials, spinel Li4Ti5O12 was successfully synthesized by a modified rheological phase method. Thermogravimetric analysis and differential scanning calorimetry (TG–DSC) of the thermal decomposition process of the precursor and X-ray diffraction (XRD) data indicate the crystallization of lithium titanates has occurred at 580 °C, and main phase Li4Ti5O12 has obtained at 600 °C. Laser granulometer and scanning electron microscope (SEM) have been employed to estimate the particle size distribution, morphology and microstructure of the products. It reveals the prepared Li4Ti5O12 powder had a small particle size (about 140 nm) and narrow size distribution (d0.1 = 0.07, d0.5 = 0.139, d0.9 = 2.813 μm). Galvanostatic charge and discharge tests were carried out to characterize the electrochemical performances of Li4Ti5O12. The result indicates that the Li4Ti5O12 electrode material obtained from the precursor that had been experienced heat treatment at 110 °C exhibited discharge capacities of 161.6, 156.5 and 112.3 mAh g−1 after 50 cycles at current rates 1, 2.5 and 10 C, respectively, demonstrating excellent high rate performance, due to the pure and well crystallized Li4Ti5O12 with ultrafine particles and narrow size distribution. 相似文献
10.
Nano-sized Li4Ti5O12 powders with high dispersivity were fabricated by a sol-gel process using P123 as surfactant, which exhibited much better high rate performance towards Li+ insertion/extraction as compared to the densely aggregated Li4Ti5O12 particles although the primary grain sizes of both samples were almost the same. The Li4Ti5O12 electrode prepared from the well-dispersed nanopowders can preserve 88.6% of the capacity at 0.1 A g−1 when being cycled at 1 A g−1, which is obviously higher than that of the densely aggregated sample, in which only 30% capacity can be retained. By improving the dispersivity, the specific surface area of the Li4Ti5O12 nanoparticles, hence the electrode-electrolyte contact area was increased; meanwhile, more homogeneous mixing of the active materials with carbon black was achieved. All these factors might have resulted in the better high rate performance. 相似文献
11.
Zijia Yu Xianfa Zhang Guiling Yang Jing Liu Jiawei Wang Rongshun Wang Jingping Zhang 《Electrochimica acta》2011,(24):8611
Li4Ti4.9V0.1O12 nanometric powders were synthesized via a facile solid-state reaction method under inert atmosphere. XRD analyses demonstrated that the V-ions successfully entered the structure of cubic spinel-type Li4Ti5O12 (LTO), reduced the lattice parameter and no impurities appeared. Compared with the pristine LTO, the electronic conductivity of Li4Ti4.9V0.1O12 powders is as high as 2.9 × 10−1 S cm−1, which should be attributed to the transformation of some Ti3+ from Ti4+ induced by the efficient V-ions doping and the deficient oxygen condition. Meanwhile, the results of XPS and EDS further proved the coexistence of V5+ and Ti3+ ions. This mixed Ti4+/Ti3+ ions can remarkably improve its cycle stability at high discharge–charge rates because of the enhancement of the electronic conductivity. The images of SEM showed that Li4Ti4.9V0.1O12 powders have smaller particles and narrower particle size distribution under 330 nm. And EIS indicates that Li4Ti4.9V0.1O12 has a faster lithium-ion diffusivity than LTO. Between 1.0 and 2.5 V, the electrochemical performance, especially at high rates, is excellent. The discharge capacities are as high as 166 mAh g−1 at 0.5C and 117.3 mAh g−1 at 5C. At the rate of 2C, it exhibits a long-term cyclability, retaining over 97.9% of its initial discharge capacity beyond 1713 cycles. These outstanding electrochemical performances should be ascribed to its nanometric particle size and high conductivity (both electron and lithium ion). Therefore, the as-prepared material is promising for such extensive applications as plug-in hybrid electric vehicles and electric vehicles. 相似文献
12.
Junjie Huang 《Electrochimica acta》2008,53(26):7756-7759
Li4Ti5O12/carbon nano-tubes (CNTs) composite was prepared by sol-gel method while Ti(OC4H9)4, LiCH3COO·2H2O and the n-heptane containing CNTs were used as raw materials. The characters of Li4Ti5O12/CNTs composite were determined by XRD, SEM, and TG methods. Its electrochemical properties were measured by charge-discharge cycling and impedance tests. It was found that the prepared Li4Ti5O12/CNTs presented an excellent rate capability and capacity retention. At the charge-discharge rate of 5C and 10C, its discharge capacities were 145 and 135 mAh g−1, respectively. After 500 cycles at 5C, the discharge capacity retained as 142 mAh g−1. It even could be cycled at the rate of 20C. The excellent electrochemical performance of Li4Ti5O12/CNTs electrode could be attributed to the improvement of electronic conductivity by adding conducting CNTs and the nano-size of Li4Ti5O12 particles in the Li4Ti5O12/CNTs composite. 相似文献
13.
A Li4Ti5O12/carbon/carbon nano-tubes (Li4Ti5O12/C/CNTs) composite was synthesized by using a solid-state method. For comparison, a Li4Ti5O12/carbon (Li4Ti5O12/C) composite and a pristine Li4Ti5O12 were also synthesized in the present study. The microstructure and morphology of the prepared samples are characterized by XRD and SEM. Electrochemical properties of the samples are evaluated by using galvanostatic discharge/charge tests and AC impedance spectroscopy. The results reveal that the Li4Ti5O12/C/CNTs composite exhibits the best rate capability and cycling stability among the samples of Li4Ti5O12, Li4Ti5O12/C and Li4Ti5O12/C/CNTs. At the charge-discharge rate of 0.5 C, 5.0 C and 10.0 C, its discharge capacities were 163 mAh/g, 148 mAh/g and 143 mAh/g, respectively. After 100 cycles at 5.0 C, it remained at 146 mAh/g. 相似文献
14.
The impedance rise that results from the accelerated aging of high-power lithium-ion cells containing LiNi0.8Co0.15Al0.05O2-based positive and graphite-based negative electrodes is dominated by contributions from the positive electrode. Data from various diagnostic experiments have indicated that a general degradation of the ionic pathway, apparently caused by surface film formation on the oxide particles, produces the positive electrode interface rise. One mechanistic hypothesis postulates that these surface films are components of the negative electrode solid electrolyte interphase (SEI) layer that migrate through the electrolyte and separator and subsequently coat the positive electrode. This hypothesis is examined in this article by subjecting cells with LiNi0.8Co0.15Al0.05O2-based positive and Li4/3Ti5/3O4-based negative electrodes to accelerated aging. The impedance rise in these cells was observed to be almost entirely from the positive electrode. Because reduction products are not expected on the 1.55 V Li4/3Ti5/3O4 electrode, the positive electrode impedance cannot be attributed to the migration of SEI-type fragments from the negative electrode. It follows then that the impedance rise results from mechanisms that are “intrinsic” to the positive electrode. 相似文献
15.
In recent years, spinel lithium titanate (Li4Ti5O12) as a superior anode material for energy storage battery has attracted a great deal of attention because of the excellent Li-ion insertion and extraction reversibility. However, the high-rate characteristics of this material should be improved if it is used as an active material in large batteries. One effective way to achieve this is to prepare electrode materials coated with carbon. A Li4Ti5O12/polyacene (PAS) composite were first prepared via an in situ carbonization of phenol-formaldehyde (PF) resin route to form carbon-based composite. The SEM showed that the Li4Ti5O12 particles in the composite were more rounded and smaller than the pristine one. The PAS was uniformly dispersed between the Li4Ti5O12 particles, which improved the electrical contact between the corresponding Li4Ti5O12 particles, and hence the electronic conductivity of composite material. The electronic conductivity of Li4Ti5O12/PAS composite is 10−1 S cm−1, which is much higher than 10−9 S cm−1 of the pristine Li4Ti5O12. High specific capacity, especially better high-rate performance was achieved with this Li4Ti5O12/PAS electrode material. The initial specific capacity of the sample is 144 mAh/g at 3 C, and it is still 126.2 mAh/g after 200 cycles. By increasing the current density, the sample still maintains excellent cycle performance. 相似文献
16.
Chang-Hoon HongAlfian Noviyanto Ji Heon RyuJaemyung Kim Dang-Hyok Yoon 《Ceramics International》2012,38(1):301-310
Li4Ti5O12 was synthesized by a solid-state reaction between Li2CO3 and TiO2 for applications in lithium ion batteries. The effects of the TiO2 phase and mechanochemical activation on the Li4Ti5O12 particles as well as the corresponding electrochemical properties were investigated. Rutile TiO2 was more desirable in acquiring high purity Li4Ti5O12 than anatase due to the anatase to rutile phase transformation, which was found to be more rigid in the solid-state reaction than the intact rutile phase. Mechanochemical activation of the starting materials was effective in decreasing the reaction temperature and particle size as well as increasing the Li4Ti5O12 content. The specific capacity depended significantly on the Li4Ti5O12 content, whereas the rate capability improved with decreasing particle size due to the enhanced contact area and reduced diffusion path. Overall, a 200 nm-sized Li4Ti5O12 powder with a specific capacity of 165 mAh/g could be synthesized by optimizing the milling method and starting materials. 相似文献
17.
Electrochemical performance of the carbon coated Li3V2(PO4)3 cathode material synthesized by a sol-gel method 总被引:1,自引:0,他引:1
A carbon coated Li3V2(PO4)3 cathode material for lithium ion batteries was synthesized by a sol-gel method using V2O5, H2O2, NH4H2PO4, LiOH and citric acid as starting materials, and its physicochemical properties were investigated using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX), transmission electron microscope (TEM), and electrochemical methods. The sample prepared displays a monoclinic structure with a space group of P21/n, and its surface is covered with a rough and porous carbon layer. In the voltage range of 3.0-4.3 V, the Li3V2(PO4)3 electrode displays a large reversible capacity, good rate capability and excellent cyclic stability at both 25 and 55 °C. The largest reversible capacity of 130 mAh g−1 was obtained at 0.1C and 55 °C, nearly equivalent to the reversible cycling of two lithium ions per Li3V2(PO4)3 formula unit (133 mAh g−1). It was found that the increase in total carbon content can improve the discharge performance of the Li3V2(PO4)3 electrode. In the voltage range of 3.0-4.8 V, the extraction and reinsertion of the third lithium ion in the carbon coated Li3V2(PO4)3 host are almost reversible, exhibiting a reversible capacity of 177 mAh g−1 and good cyclic performance. The reasons for the excellent electrochemical performance of the carbon coated Li3V2(PO4)3 cathode material were also discussed. 相似文献
18.
Some polyanionic compounds, e.g. TiP2O7 and LiTi2(PO4)3 with 3D framework structure were proposed to be used as anodes of lithium ion battery with aqueous electrolyte. The cyclic voltammetry properties TiP2O7 and LiTi2(PO4)3 suggested that Li-ion de/intercalation reaction can occur without serious hydrogen evolution in 5 M LiNO3 aqueous solution. The TiP2O7 and LiTi2(PO4)3 give capacities of about 80 mAh/g between potentials of −0.50 V and 0 V (versus SHE) and 90 mAh/g between −0.65 V and −0.10 V (versus SHE), respectively. A test cell consisting of TiP2O7/5 M LiNO3/LiMn2O4 delivers approximately 42 mAh/g (weight of cathode and anode) at average voltage of 1.40 V, and LiTi2(PO4)3/5 M LiNO3/LiMn2O4 delivers approximately 45 mAh/g at average voltage of 1.50 V. Both as-assembled cells suffered from short cycle life. The capacity fading may be related to deterioration of anode material. 相似文献
19.
A series of spinel Li4Ti5O12 samples were synthesized via a composite molten-salt method (CMSM) using the mixtures of LiCl and KCl with different L values (L is defined as the molar ratio of LiCl:KCl) as the reaction media. It is found that the melting point of the composite molten salt can effectively influence the formation of particles, and leads to different electrochemical performances of the as-prepare Li4Ti5O12. The investigations of X-ray diffraction (XRD), particle size distribution (PSD), Brunauer-Emmet-Teller (BET) surface area, and scanning electron microscopy (SEM) indicate that the as-prepared Li4Ti5O12 with L = 1.5 is a pure phase, and has uniform homogeneous octahedral shape particles, rather narrow PSD, and high BET surface area. Electrochemical tests show that the optimized Li4Ti5O12 with L = 1.5 has an initial discharge capacity of 169 mAh g−1 and an initial charge-discharge efficiency of 94% at 0.2 C rate, and achieves good rate performances from 0.2 C to 5 C. 相似文献
20.
Nano-sized silver particle (<20 nm) was highly dispersed on the surface of Li4Ti5O12 particles by an electroless deposition method. The Ag additive played a positive role in improving the electrical contact between Li4Ti5O12 particles and the current collector and therefore improved the high rate capacity of Li4Ti5O12, but it did not take part in the electrochemical reactions with Li+ in Li4Ti5O12/Ag composite during the cycling. The experimental results showed that the smaller the silver particles and the more homogeneous dispersion of silver particles in the Li4Ti5O12 matrix, the better the cycling performance we obtained. 相似文献