共查询到20条相似文献,搜索用时 31 毫秒
1.
Bo Jin Hal-Bon Gu Wanxi Zhang Kyung-Hee Park Guangping Sun 《Journal of Solid State Electrochemistry》2008,12(12):1549-1554
LiFePO4-C nanoparticles were synthesized by a hydrothermal method and subsequent high-energy ball-milling. Different carbon conductive
additives including nanosized acetylene black (AB) and multi-walled carbon nanotube (MWCNT) were used to enhance the electronic
conductivity of LiFePO4. The structural and morphological performance of LiFePO4-C nanoparticles was investigated by X-ray diffraction (XRD) and scanning electron microscopy. The electrochemical properties
of LiFePO4-C/Li batteries were analyzed by cyclic voltammetry and charge/discharge tests. XRD results demonstrate that LiFePO4-C nanoparticles have an orthorhombic olivine-type structure with a space group of Pnma. LiFePO4-C/Li battery with 5 wt% MWCNT displays the best electrochemical properties with a discharge capacity of 142 mAh g−1 at 0.25 C at room temperature. 相似文献
2.
Lucangelo Dimesso Susanne Jacke Christina Spanheimer Wolfram Jaegermann 《Journal of Solid State Electrochemistry》2012,16(3):911-919
An uncomplicated Pechini-assisted sol–gel process in aqueous solutions is used for the synthesis of Li–Co phosphate powders
as cathode materials. The powders are annealed under different conditions in flowing nitrogen and in flowing air. The structural,
morphological, and electrochemical properties are strongly dependent upon the annealing conditions. After the treatment in
air, the X-ray diffraction (XRD) patterns reveal the presence of LiCoPO4 as a single phase. The morphology of the powders consists of a homogeneous and good interconnected blend of grains with different
sizes; the cyclic voltammetry (CV) curves show a very good reversibility with very close values of the mean peak maxima in
the cathodic region. The electrochemical measurements deliver a discharge specific capacity of 37 mAhg−1 at a discharge rate of C/25 at room temperature. After annealing in nitrogen, the XRD analysis detects the formation of Li4P2O7 and to Co2P as secondary phases; the morphological investigation indicated that the LiCoPO4 particles took shape of prisms with an average size of 2 μm. The CV curves are associated with a large polarization and poor
irreversibility. The electrochemical measurements deliver a discharge specific capacity of 42 mAh g−1 at a discharge rate of C/25 at room temperature and lower capacity fade (approx. 35%). 相似文献
3.
Angelina Sarapulova Daria Mikhailova Ljubomira Ana Schmitt Steffen Oswald Natalia Bramnik Helmut Ehrenberg 《Journal of Sol-Gel Science and Technology》2012,62(1):98-110
LiCoPO4-coated disordered carbon nanofibers (CNFs/LiCoPO4) were obtained by a sol–gel method, using triethyl phosphite or triethyl phosphate as the phosphorous source. The crystal
structure of the products was analyzed by X-ray powder diffraction, while morphology was studied using scanning electron microscopy,
transmission electron microscopy, Auger electron spectroscopy and X-ray photoelectron spectroscopy. Optimal synthesis conditions
for the CNFs/LiCoPO4 in light of the best electrochemical performance are discussed. The best discharge capacity 105 mAh/g (or ca. 63% of the
theoretical capacity) shows the material with 40% CNFs/LiCoPO4 and addition coating by carbon black. This composition has a best purity of active materials and point coverage of CNFs.
The X-ray photoelectron C1s spectra of the CNFs surface without and with sputter erosion show enhancement of C–O bonds at
the fiber surface, which does not influence significantly electrochemical behavior of the composite materials. 相似文献
4.
Qiong Jiang Yunlong Xu Chongjun Zhao Xiuzhen Qian Shaowei Zheng 《Journal of Solid State Electrochemistry》2012,16(4):1503-1508
A novel LiFePO4/Carbon aerogel (LFP/CA) nanocomposite with 3D conductive network structure was synthesized by using carbon aerogels as both
template and conductive framework, and subsequently wet impregnating LiFePO4 precursor inside. The LFP/CA nanocomposite was characterized by X-ray diffraction (XRD), TG, SEM, TEM, nitrogen sorption,
electrochemical impedance spectra and charge/discharge test. It was found that the LFP/CA featured a 3D conductive network
structure with LiFePO4 nanoparticles ca. 10–30 nm coated on the inside wall of the pore of CA. The LFP/CA electrodes delivered discharge capacity
for LiFePO4 of 157.4, 147.2, 139.7, 116.3 and 91.8 mA h g−1 at 1 °C, 5 °C, 10 °C, 20 °C and 40 °C, respectively. In addition, the LFP/CA electrode exhibited good cycling performance,
which lost less than 1% of discharge capacity over 100 cycles at a rate of 10 °C. The good high rate performances of LiFePO4 were attributed to the unique 3D conductive network structure of the nanocomposite. 相似文献
5.
Xin Zhang Suqin Liu Kelong Huang Shuxin Zhuang Jun Guo Tao Wu Ping Cheng 《Journal of Solid State Electrochemistry》2012,16(3):937-944
The macroporous Li3V2(PO4)3/C composite was synthesized by oxalic acid-assisted carbon thermal reaction, and the common Li3V2(PO4)3/C composite was also prepared for comparison. These samples were characterized by X-ray diffraction (XRD), scanning electron
microscope (SEM), and electrochemical performance tests. Based on XRD and SEM results, the sample has monoclinic structure
and macroporous morphology when oxalic acid is introduced. Electrochemical tests show that the macroporous Li3V2(PO4)3/C sample has a high initial discharge capacity (130 mAh g−1 at 0.1 C) and a reversible discharge capacity of 124.9 mAh g−1 over 20 cycles. Moreover, the discharge capacity of the sample is still 91.5 mAh g−1, even at a high rate of 2 C, which is better than that of the sample with common morphology. The improvement in electrochemical
performance should be attributed to its improved lithium ion diffusion coefficient for the macroporous morphology, which was
verfied by cyclic voltammetry and electrochemical impedance spectroscopy. 相似文献
6.
E. J. Kim H. Y. Xu J. S. Lim J. W. Kang J. H. Gim Vinod Mathew Jaekook Kim 《Journal of Solid State Electrochemistry》2012,16(1):149-155
LiCoPO4 nanoparticles were synthesized by standard and glucose-assisted sol–gel methods for use as cathodes in lithium-ion batteries.
The effect of glucose on the characteristics of the formed LiCoPO4 nanoparticles was investigated by TGA, XRD, and FESEM. The TGA results indicated gradual decomposition of glucose in the
temperature range 400–700 °C. The XRD results showed olivine phases in addition to small traces of Co3O4 for samples calcined at 400 °C while pure olivine phases were confirmed for the 700 °C calcined samples. The addition of
glucose strongly suggests promotion of LiCoPO4 crystallization, as revealed by FESEM studies. The electrochemical measurements pertaining to LiCoPO4 samples calcined at 400 °C suggested an enhancement of initial discharge capacity from 103.3 to 144.6 mAh/g for the standard
and glucose-based electrodes, respectively. Further, the effects of conductive additive and excess lithium on the electrochemical
performance of LiCoPO4 have also been investigated. 相似文献
7.
Xiaochang Qiao Jiandong Yang Yaobin Wang Quanqi Chen Tingting Zhang Li Liu Xianyou Wang 《Journal of Solid State Electrochemistry》2012,16(3):1211-1217
LiVPO4F/C composites with better electrochemical performance were prepared by calcination of LiF and amorphous vanadium phosphorus
oxide (VPO) intermediate synthesized by a sol–gel method using H3PO4, V2O5 and citric acid as raw materials. The properties of LiVPO4F/C composites were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical tests.
The analysis of XRD patterns and Fourier transform infrared spectra (FTIR) reveal that VPO intermediate prepared by sol–gel
method is amorphous and VPO4 may exist in VPO intermediate. The compositions of LiVPO4F/C composites are related to the calcination temperature for preparation of amorphous VPO/C intermediate and LiVPO4F/C composite prepared by VPO/C synthesized at 700°C consists of a single crystal phase of LiVPO4F. The electrochemical tests show that LiVPO4F/C composite prepared by VPO/C synthesized at 700°C exhibits higher discharge capacity and excellent cycle performance. This
LiVPO4F/C composite displays discharge capacity of 133 mAh g−1 at 0.5 C (78 mA g−1) and remains capacity retention of 96.8% after 30 cycles, even at a high rate of 5 C, the composite exhibits high discharge
capacity of 115 mAh g−1 and capacity retention of 97% after 100 cycles. 相似文献
8.
M. Prabu S. Selvasekarapandian M. V. Reddy B. V. R. Chowdari 《Journal of Solid State Electrochemistry》2012,16(5):1833-1839
Olivine-structured LiCoPO4 is synthesized by a Pechini-type polymer precursor method. The structure and the morphology of the compounds are studied
by the Rietveld-refined X-ray diffraction, scanning electron microscopy, Brunauer, Emmett, and Teller surface area technique,
infrared spectroscopy, and Raman spectroscopy techniques, respectively. The ionic conductivity (σ ionic), dielectric, and electric modulus properties of LiCoPO4 are investigated on sintered pellets by impedance spectroscopy in the temperature range, 27–50 °C. The σ (ionic) values at 27 and 50 °C are 8.8 × 10−8 and 49 × 10−8 S cm−1, respectively with an energy of activation (E
a) = 0.43 eV. The electric modulus studies suggest the presence of non-Debye type of relaxation. Preliminary charge–discharge
cycling data are presented. 相似文献
9.
Zhao Yang Gao-Shao Cao Jian Xie Xin-Bing Zhao 《Journal of Solid State Electrochemistry》2012,16(3):1271-1277
LiMnPO4, with a particle size of 50–150 nm, was prepared by oleic acid-assisted solid-state reaction. The materials were characterized
by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The electrochemical
properties of the materials were investigated by galvanostatic cycling. It was found that the introduction of oleic acid in
the precursor led to smaller particle size and more homogeneous size distribution in the final products, resulting in improved
electrochemical performance. The electrochemical performance of the sample could be further enhanced by Co doping. The mechanism
for the improvement of the electrochemical performance was investigated by Li-ion chemical diffusion coefficient
( [(D)\tilde]\textLi ) \left( {{{\tilde{D}}_{\text{Li}}}} \right) and electrochemical impedance spectroscopy measurements. The results revealed that the
[(D)\tilde]\textLi {\tilde{D}_{\text{Li}}} values of LiMnPO4 measured by cyclic voltammetry method increase from 9.2 × 10−18 to 3.0 × 10−17 cm2 s−1 after Co doping, while the charge transfer resistance (R
ct) can be decreased by Co doping. 相似文献
10.
Spherical Li[Ni1/3Co1/3Mn1/3]O2 cathode materials with different microstructure have been prepared by a continuous carbonate co-precipitation method using
LiOH⋅H2O, Li2CO3, CH3COOLi⋅2H2O and LiNO3 as lithium source. The effects of Li source on the physical and electrochemical properties of Li[Ni1/3Co1/3Mn1/3]O2 are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical measurements. The results
show that the morphology, tap density and high rate cycling performance of Li[Ni1/3Co1/3Mn1/3]O2 spherical particles are strongly affected by Li source. Among the four Li sources used in this study, LiOH⋅H2O is beneficial to enhance the tap density of Li[Ni1/3Co1/3Mn1/3]O2, and the tap density of as-prepared sample reaches 2.32 g cm−3. Meanwhile, Li2CO3 is preferable when preparing the Li[Ni1/3Co1/3Mn1/3]O2 with high rate cycling performance, upon extended cycling at 1 and 5C rates, 97.5% and 92% of the initial discharge capacity
can be maintained after 100 cycles. 相似文献
11.
H. M. Wu J. P. Tu X. T. Chen Y. Li X. B. Zhao G. S. Cao 《Journal of Solid State Electrochemistry》2007,11(2):173-176
Spinel LiMn2−x
Ni
x
O4 compounds doped with a range of Ni (x=0–0.06) were synthesized by a spray-drying method. The structure and morphology characteristics of the powders were studied in detail by means of X-ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy. The XRD data reveal that all the samples have well-defined spinel structure, but, with the increase in Ni content, the doped lithium manganese spinels have smaller lattice constant. The undoped and doped spinel LiMn2O4 particles are fine, narrowly distributed, and well crystallized. The electrochemical characteristics of the samples are measured in the coin-type cells in a potential range of 3.2–4.35 V vs Li/Li+. All cyclic voltammogram curves exhibit two pairs of redox reaction peaks, but, among them, there are some differences about the peak split. With the increase in the Ni content, the specific capacities of the samples decrease slightly, but their cyclic ability increases. 相似文献
12.
Layered LiNi1/3Co1/3Mn1/3O2 nanoparticles were prepared by modified Pechini method and used as cathode materials for Li-ion batteries. The pyrolytic
behaviors of the foamed precursors were analyzed by use of simultaneous thermogravimetric and differential thermal analysis
(TG-DTA). Structure, morphology and electrochemical performance characterization of the samples were investigated by X-ray
diffraction (XRD), field emission scanning electron macroscopy(SEM), Brunauer-Emmett-Teller (BET) specific surface area and
charge–discharge tests. The results showed that the samples prepared by modified Pechini method caclined at 900 °C for 10 h
were indexed to pure LiNi1/3Co1/3Mn1/3O2 with well hexagonal structure. The particle size was in a range of 100–300 nm. The specific surface area was larger than
that of the as-obtained sample by Pechini method. Initial discharge capacity of 163.8 mAh/g in the range 2.8–4.4 V (vs. Li/Li+) and at 0.1C for LiNi1/3Co1/3Mn1/3O2 prepared by modified Pechini method was obtained, higher than that of the sample prepared by Pechini method (143.5 mAh/g).
Moreover, the comparison of electrochemical results at different current rates indicated that the sample prepared by modified
Pechini method exhibited improved rate capability. 相似文献
13.
Magnetic Co3O4 nanoparticles were prepared by using microporous regenerated cellulose films as sacrificial scaffolds. The cellulose macromolecules
and the porous structure of the films made them used as spatially confined reacting sites where Co(OH)2 nanoparticles could be synthesized in situ. When the cellulose matrix was removed by sintering at 500 °C, Co3O4 nanoparticles were obtained. XRD and XPS indicated that the prepared nanoparticles were pure Co3O4 without any impurity. TEM and SEM images revealed that the particle size of the nanoparticles was smaller than 100 nm. The
nanoparticles had weak ferromagnetic properties at 25 °C. Furthermore, the pronounced quantum confinement effects of the synthesized
nanoparticles have been observed, the optical bandgap energies determined were about 1.92 ~ 2.12 and 2.74 ~ 2.76 eV for O2− → Co3+ and O2− → Co2+ charge-transfer processes, respectively. Furthermore, the resulted Co3O4 nanoparticles behaved stable electrochemical performance with promising applications in the electrode for lithium ion battery. 相似文献
14.
Yongli Cui Wenjing Bao Zheng Yuan Quanchao Zhuang Zhi Sun 《Journal of Solid State Electrochemistry》2012,16(4):1551-1559
A comparative study of submicro-crystalline spinel LiMn2O4 powders prepared by two different soft chemical routes such as hydrothermal and sol–gel methods is made. The dependence of
the physicochemical properties of the spinel LiMn2O4 powder has been extensively investigated by using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron
microscope, cyclic voltammogram, charge–discharge test, and electrochemical impedance spectroscopy (EIS). The results show
that the electrochemical performances of spinel LiMn2O4 depend strongly upon the synthesis method. The LiMn2O4 powder prepared by hydrothermal route has higher specific capacity and better cycling performance than the one synthesized
from sol–gel method. The former has the max discharge capacity of 114.36 and 99.78 mAh g−1 at the 100th cycle, while the latter has the max discharge capacity of 98.67 and 60.25 mAh g−1 at the 100th cycle. The selected equivalent circuit can fit well the EIS results of synthesized LiMn2O4. For spinel LiMn2O4 from sol–gel method and hydrothermal route in the first charge process R
SEI remain almost invariable, R
e and R
ct first decreasing and then increasing with the increase of polarization potential. 相似文献
15.
In this paper, the electrochemical performances of a layered double hydroxide, [Ni4Al(OH)10]NO3, of different particle sizes are studied. The results show that the particle size of the sample has evident effects on its
discharge capacity at high current density, although a larger capacity may be observed for the bigger particles when they
are discharged at lower current densities, e.g. 0.2 A g−1. However, the capacity decreases more quickly than that of the sample in smaller particle size when the current density increases.
For example, the discharge capacity of the smallest particle remains as high as 180 mAh·g−1 even at very high current density, e.g. 4.0 A g−1. The results also show that long time soaked electrodes in 7 mol l−1 KOH have improved performance, especially for the hydrothermal samples. It also seems that there is an optimal size for materials,
which can maintain their performance for longer time. 相似文献
16.
G. Vijayakumar S. N. Karthick A. R. Sathiya Priya S. Ramalingam A. Subramania 《Journal of Solid State Electrochemistry》2008,12(9):1135-1141
New poly (vinylidenefluoride-co-hexafluoro propylene) (PVDF-HFP)/CeO2-based microcomposite porous polymer membranes (MCPPM) and nanocomposite porous polymer membranes (NCPPM) were prepared by
phase inversion technique using N-methyl 2-pyrrolidone (NMP) as a solvent and deionized water as a nonsolvent. Phase inversion occurred on the MCPPM/NCPPM
when it is treated by deionized water (nonsolvent). Microcomposite porous polymer electrolytes (MCPPE) and nanocomposite porous
polymer electrolytes (NCPPE) were obtained from their composite porous polymer membranes when immersed in 1.0 M LiClO4 in a mixture of ethylene carbonate/dimethyl carbonate (EC/DMC) (v/v = 1:1) electrolyte solution. The structure and porous morphology of both composite porous polymer membranes was examined
by scanning electron microscope (SEM) analysis. Thermal behavior of both MCPPM/NCPPM was investigated from DSC analysis. Optimized
filler (8 wt% CeO2) added to the NCPPM increases the porosity (72%) than MCPPM (59%). The results showed that the NCPPE has high electrolyte
solution uptake (150%) and maximum ionic conductivity value of 2.47 × 10−3 S cm−1 at room temperature. The NCPPE (8 wt% CeO2) between the lithium metal electrodes were found to have low interfacial resistance (760 Ω cm2) and wide electrochemical stability up to 4.7 V (vs Li/Li+) investigated by impedance spectra and linear sweep voltammetry (LSV), respectively. A prototype battery, which consists
of NCPPE between the graphite anode and LiCoO2 cathode, proves good cycling performance at a discharge rate of C/2 for Li-ion polymer batteries. 相似文献
17.
Nano-structured spinel Li2Mn4O9 powder was prepared via a combustion method with hydrated lithium acetate (LiAc·2H2O), manganese acetate (MnAc2·4H2O), and oxalic acid (C2H2O4·2H2O) as raw materials, followed by calcination of the precursor at 300 °C. The sample was characterized by X-ray diffraction,
scanning electron microscope, and energy-dispersive X-ray spectroscopy techniques. Electrochemical performance of the nano-Li2Mn4O9 material was studied using cyclic voltammetry, ac impedance, and galvanostatic charge/discharge methods in 2 mol L−1 LiNO3 aqueous electrolyte. The results indicated that the nano-Li2Mn4O9 material exhibited excellent electrochemical performance in terms of specific capacity, cycle life, and charge/discharge
stability, as evidenced by the charge/discharge results. For example, specific capacitance of the single Li2Mn4O9 electrode reached 407 F g−1 at the scan rates of 5 mV s−1. The capacitor, which is composed of activated carbon negative electrode and Li2Mn4O9 positive electrode, also exhibits an excellent cycling performance in potential range of 0–1.6 V and keeps over 98% of the
maximum capacitance even after 4,000 cycles. 相似文献
18.
Li0.97Er0.01FePO4/C composite was prepared by solid-state reaction, using particle modification with amorphous carbon from the decomposition
of glucose and lattice doping with supervalent cation Er3+. All samples were characterized by X-ray diffraction, scanning electron microscopy, multi-point Brunauer Emmett and Teller
methodes. The electrochemical tests show Li0.97Er0.01FePO4/C composite obtains the highest discharge specific capacity of 154 mAh g−1 at C/10 rate and the best rate capability. Its specific capacity reaches 131 mAh g−1 at 2C rate. Its capacity loss is only 14.9 % when the rate varies from C/10 to 2C. 相似文献
19.
本工作采用水热法结合银镜反应制备出一系列不同Ag负载量(2.2%、4.0%、6.4%,w/w)改性的3D纳米网状结构Ag@TiO2薄膜电极。利用电感耦合等离子体技术(ICP)、X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和X射线能谱(EDX)等表征手段测试所合成材料的形貌及成分,实验结果表明Ag纳米颗粒可以成功沉积在TiO2纳米线表面。电化学测试数据则表明,4.0%(w/w)负载量的Ag@TiO2相比于未改性和其他负载量的TiO2纳米线具有更好的倍率性能和更稳定的可逆容量。在50,100,200,400,800和1 200 mA·g-1的电流密度条件下,该改性电极的放电容量可分别达到261.4,253.7,239.5,216.5,193.1和185.1 mAh·g-1,在200 mA·g-1下循环80次后容量保持率仍能达到99.8%。 相似文献
20.
采用水热法结合银镜反应制备出一系列不同Ag负载量(2.2%、4.0%、6.4%,w/w)改性的3D纳米网状结构Ag@Ti O2薄膜电极。利用电感耦合等离子体技术(ICP)、X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和X射线能谱(EDX)等表征手段测试所合成材料的形貌及成分,实验结果表明Ag纳米颗粒可以成功沉积在Ti O2纳米线表面。电化学测试数据则表明,4.0%(w/w)负载量的Ag@Ti O2相比于未改性和其他负载量的Ti O2纳米线具有更好的倍率性能和更稳定的可逆容量。在50,100,200,400,800和1 200 m A·g~(-1)的电流密度条件下,该改性电极的放电容量可分别达到261.4,253.7,239.5,216.5,193.1和185.1 m Ah·g~(-1),在200 m A·g~(-1)下循环80次后容量保持率仍能达到99.8%。 相似文献