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1.
Single-phase LiCoPO4 nanoparticles were synthesized by solid-state reaction method and subsequent high-energy ball milling. The electrochemical
properties of LiCoPO4/Li batteries were analyzed by ac impedance experiments, cyclic voltammetry (CV), and charge/discharge tests. The structural
and morphological performance of LiCoPO4 nanoparticles was investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron
microscope (TEM). The XRD result demonstrated that LiCoPO4 nanoparticles had an orthorhombic olivine-type structure with a space group of Pmnb. Different conductive additives including
acetylene black and carbon black (SP270) were used to fabricate electrodes. The morphologies of the electrodes and different
conductive additives were observed by field emission-scanning electron microscopy (FE-SEM). LiCoPO4/Li battery with acetylene black showed the best electrochemical properties, and exhibited a discharge plateau at around 4.7 V
with an initial discharge capacity of 110 mAh g−1 at a discharge current density of 0.05 mA cm−2 at 25 °C. 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.
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
4.
A series of Li3V2(PO4)3/C composites with different amounts of carbon are synthesized by a combustion method. The physical and electrochemical properties of the Li3V2(PO4)3/C composites are investigated by X-ray diffraction, element analysis, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy and electrochemical measurements. The effects of carbon content of Li3V2(PO4)3/C composites on its electrochemical properties are conducted with cyclic voltammetry and electrochemical impedance. The experiment results clearly show that the optimal carbon content is 4.3 wt %, and more or less amount of carbon would be unfavorable to electrochemical properties of the Li3V2(PO4)3/C electrode materials. The results would provide some basis for further improvement on the Li3V2(PO4)3 electrode materials. 相似文献
5.
Lin Yang Lifang Jiao Yanli Miao Huatang Yuan 《Journal of Solid State Electrochemistry》2010,14(6):1001-1005
The olivine-typed cathode materials of LiFePO4were prepared via solid-state reaction under argon atmosphere and co-doped by manganese and fluorine to improve their electrochemical
performances. The crystal structure, morphology, and electrochemical properties of the prepared samples were investigated
using X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectrum, X-ray photoelectron spectroscopy,
cyclic voltammetry, and charge–discharge cycle measurements. The result showed that the electrochemical performance of LiFePO4 had been improved dramatically by Mn–F co-doping. The initial discharge capacity of LiFe0.99Mn0.01 (PO4)2.99/3F0.01/C samples reached 140.2 mAh/g at 1C rate and only had a small amount of fading in 50 cycles. 相似文献
6.
New composite cathode materials xLiMn2O4/(1 ? x) LiCoO2(x = 0.7, 0.6, 0.5 и 0.4) were obtained by mechanical activation. According to scanning electron microscopy data, the process was accompanied by pronounced dispersion and fine mixing of the initial components. In the course of the preparation and electrochemical cycling of the composites, LiMn2O4 and LiCoO2 partially reacted, leading to the replacement of manganese with cobalt in the structure of spinel, which was detected by powder X-ray diffraction (XRD), IR and X-ray photoelectron spectroscopy (XPS), and cyclic chronopotentiometry. The specific discharge capacity of composites was ~100 mAh/g. 相似文献
7.
The effect of fluorine doping on the electrochemical performance of LiFePO4/C cathode material is investigated. The stoichiometric proportion of LiFe(PO4)1−x
F3x
/C (x = 0.01, 0.05, 0.1, 0.2) materials was synthesized by a solid-state carbothermal reduction route at 650 °C using NH4F as dopant. X-ray diffraction, scanning electron microscope, energy-dispersive X-ray, and X-ray photoelectron spectroscopy
analyses demonstrate that fluorine can be incorporated into LiFePO4/C without altering the olivine structure, but slightly changing the lattice parameters and having little effect on the particle
sizes. However, heavy fluorine doping can bring in impurities. Fluorine doping in LiFePO4/C results in good reversible capacity and rate capability. LiFe(PO4)0.95 F0.15/C exhibits highest initial capacity and best rate performance. Its discharge capacities at 0.1 and 5 C rates are 156.1 and
119.1 mAh g−1, respectively. LiFe(PO4)0.95 F0.15/C also presents an obviously better cycle life than the other samples. We attribute the improvement of the electrochemical
performance to the smaller charge transfer resistance (R
ct) and influence of fluorine on the PO43− polyanion in LiFePO4/C. 相似文献
8.
Yongguang Liang Xiaoyan Han Zonghui Yi Wenchao Tang Liqun Zhou Jutang Sun Shuijin Yang Yunhong Zhou 《Journal of Solid State Electrochemistry》2007,11(8):1127-1131
Rod-like CaMoO4 nanocrystals were synthesized via a template-based rheological phase reaction route as a novel method. The physical characterization
was carried out by thermogravimetric/differential thermal analysis (TG/DTA), X-ray diffraction (XRD), scanning electron microscopy
(SEM), transmission electron microscopy (TEM), and elected-area electron diffraction (SAED). A structure-directed role of
hexamethylene tetramine (HMTA) was observed during the formation of CaMoO4 nanocrystals. The electrochemical performance of CaMoO4 as anode for lithium ion batteries has also been investigated by galvanostatic cycling and AC impedance spectroscopy. CaMoO4/Li cell can deliver superior capacity than theoretical value in the initial cycle, and the much improved capacity was attributed
to the contribution of oxygen besides the reduction of molybdenum during lithium insertion. Furthermore, a charge capacity
of 276 and 438 mAh/g was retained after 50 cycles in the range of 0.01–2.50 V vs Li at a current density of 100 and 200 mA/g,
respectively. The particle size and morphological properties were found to play an important role in fast lithium insertion/extraction
performance and cycling stability at high rate. 相似文献
9.
Chengfeng Li Ning Hua Chenyun Wang Xueya Kang Tuerdi Wumair Ying Han 《Journal of Solid State Electrochemistry》2011,15(9):1971-1976
LiFePO4/C composite cathode material is prepared by ball milling with the assistance of EDTA chelation with using water as the media
of ball mill procedure. FePO4 and LiOH are used as starting materials; a certain amount of glucose is used as carbon sources and reduction agent. The structure
and morphology of the composite are characterized by X-ray diffraction and scanning electron microscopy. Cyclic voltammetry,
AC impedance measurements, and galvanostatic charge–discharge and cycling performances are used to characterize its electrochemical
properties. The results indicate that the performances of composites prepared by chelation-assisted method are much better
than common ball milling method which using alcohol or acetone as the media of ball mill procedure. The stable discharge capacity
of the prepared composite is 150 and 105 mAh g−1 at 1 and 10 C rate, respectively. 相似文献
10.
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
11.
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
12.
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
13.
Lei Ge 《Journal of Sol-Gel Science and Technology》2007,44(3):263-268
Novel visible-light-activated In2O3–CaIn2O4 photocatalysts were developed in this paper through a sol–gel method. The photocatalytic activities of In2O3–CaIn2O4 composite photocatalysts were investigated based on the decomposition of methyl orange under visible light irradiation (λ > 400 nm).
The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive
spectrum (EDS), X-ray photoelectron spectroscopy (XPS) and UV–vis diffused reflectance spectroscopy (DRS). The results revealed
that the In2O3–CaIn2O4 composite samples with different In2O3 and CaIn2O4 content can be obtained by controlling the synthesis temperature, and the composite photocatalysts extended the light absorption
spectrum toward the visible region. The photocatalytic tests indicated that the composite samples demonstrated high visible-light
activity for decomposition of methyl orange. The significant enhancement in the In2O3–CaIn2O4 photo-activity under visible light irradiation can be ascribed to the efficient separation of photo-generated carriers in
the In2O3 and CaIn2O4 coupling semiconductors. 相似文献
14.
Xiangzhong Ren Yingkai Jiang Peixin Zhang Jianhong Liu Qianling Zhang 《Journal of Sol-Gel Science and Technology》2009,51(2):133-138
One-dimensional (1D) submicron-belts of V2O5 have been prepared by a sol–gel route using V2O5, H2O2 and aniline as starting materials. Thermogravimetric and differential thermal analysis, X-ray diffraction, Fourier transform
infrared spectroscopy and scanning electron microscopy were employed to characterize the samples. Electrochemical behaviors
as cathode material in rechargeable lithium-ion batteries were investigated by galvanostatic charge–discharge measurement
and cyclic voltammeter. The results showed that the synthesized V2O5 appeared to be submicron-belts and orthorhombic structure. The V2O5 submicron-belts exhibited a high initial discharge capacity of 346 mAh/g and stayed 240 mAh/g after 20 cycles at 0.1 C discharge
rate in the potential region 1.8–4.0 V. 相似文献
15.
A very simple and rapid method for synthesizing LiCoPO4/C nanocomposite has been developed via microwave heating. X-ray diffraction confirmed that nanosized olivine LiCoPO4 was successfully synthesized. Scanning electron microscopy and transmission electron microscopy verified that LiCoPO4 displays small powders with an average size of ~150 nm and is also coated with uniform amorphous carbon film of ~10 nm in thickness. Compared with pure LiCoPO4, LiCoPO4/C composite presented enhanced electrochemical Li-ion intercalation performances. Cyclic voltammetric and electrical tests disclosed that the Li-ion diffusion, the reversibility of lithium extraction/insertion and electrical conductivity were significantly improved in LiCoPO4/C composite. 相似文献
16.
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
17.
Guan Wang Yan Cheng Manming Yan Zhiyu Jiang 《Journal of Solid State Electrochemistry》2007,11(4):457-462
Three kinds of LiFePO4 materials, mixed with carbon (as LiFePO4/C), doped with Ti (as Li0.99Ti0.01FePO4), and treated both ways (as Li0.99Ti0.01FePO4/C composite), were synthesized via ball milling by solid-state reaction method. The crystal structure and electrochemical
behavior of the materials were investigated using X-ray diffraction, SEM, TEM, cyclic voltammetry, and charge/discharge cycle
measurements. It was found that the electrochemical behavior of LiFePO4 could be increased by carbon coating and Ti-doping methods. Among the materials, Li0.99Ti0.01FePO4/C composite presents the best electrochemical behavior, with an initial discharge capacity of 154.5 mAh/g at a discharge
rate of 0.2 C, and long charge/discharge cycle life. After 120 cycles, its capacity remains at 92% of the initial capacity.
The Li0.99Ti0.01FePO4/C composite developed here can be used as the cathode material for lithium ion batteries. 相似文献
18.
Yi-Chen Kuo Hao -Ting Peng Yaoming Xiao Jeng-Yu Lin 《Journal of Solid State Electrochemistry》2016,20(6):1625-1631
In this study, the effect of the sol-gel starting materials with different particle sizes on the sol-gel-synthesized spinel Li4Ti5O12 (LTO) was systematically investigated. The physical and electrochemical properties of the synthesized materials were characterized by X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller-specific surface area analyses, galvanostatic charge/discharge tests, cyclic voltammetry, and electrochemical impedance spectroscopy. It was found that the initial particle size of sol-gel starting material played a crucial role on the properties of as-prepared LTOs. The LTO synthesized with the relatively finer particle size of starting materials possessed relatively smaller particle size and larger specific surface area and therefore resulted in the superior electrochemical properties. The initial discharge capacity of the as-prepared LTO exhibited 168.2, 150.6, and 142.7 mAh g?1 at current densities of 1, 5, and 10 C, respectively, and up to 95, 95, and 90 % of the corresponding initial discharge capacity was retained after 50 cycles. 相似文献
19.
R. Sathiyamoorthi P. Santhosh P. Shakkthivel T. Vasudevan 《Journal of Solid State Electrochemistry》2007,11(12):1665-1669
Layered Ti-doped lithiated nickel cobaltate, LiNi0.8Co0.2 − xTixO2 (where x = 0.01, 0.03, and 0.05) nanopowders were prepared by wet-chemistry technique. The structural properties of synthesized materials
were characterized by X-ray diffraction (XRD) and thermo-gravimetric/differential thermal analysis (TG/DTA). The morphological
changes brought about by the changes in composition of LiNi0.8Co0.2 − xTixO2 particles were examined through surface examination techniques such as scanning electron microscopy (SEM) and transmission
electron microscopy (TEM) analyses. Electrochemical studies were carried out using 2016-type coin cell in the voltage range
of 3.0–4.5 V (vs carbon) using 1 M LiClO4 in ethylene carbonate and diethyl carbonate as the electrolyte. Among the various concentrations of Ti-doped lithiated nickel
cobaltate materials, C/LiNi0.8Co0.17Ti0.03O2 cell gives stable charge–discharge features. 相似文献
20.
Carbon materials enriched with nitrogen and oxygen surface functional groups were obtained by pyrolyzing strained beer yeast
at 750 °C under an inert atmosphere. Physical and surface properties of the carbon obtained were characterized by X-ray powder
diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, Raman spectrometry, and X-ray
photoelectron spectroscopy. Results show that the carbon possesses an amorphous structure, a spherical morphology, and a high
density of surface functional groups. Electrochemical properties were evaluated by cyclic voltammetry, a galvanostatic charge–discharge
technique, and electrochemical impedance spectroscopy. The carbon has 989.65 mAh·g−1 of initial discharge capacity and a stable cycle performance for a Li–C cell. A specific capacitance of 120 F·g−1 was obtained for a single carbon electrode and good cycle performance was achieved for a symmetrical supercapacitor fabricated
using this carbon. These carbons derived from strained beer yeast have promising applications in energy storage and conversion
systems. 相似文献