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1.
Xingchao Wang Yudai Huang Dianzeng Jia Zaiping Guo Duo Ni Ming Miao 《Journal of Solid State Electrochemistry》2012,16(1):17-24
Olivine LiFePO4/C nanocomposite cathode materials with small-sized particles and a unique electrochemical performance were successfully prepared
by a simple solid-state reaction using oxalic acid and citric acid as the chelating reagent and carbon source. The structure
and electrochemical properties of the samples were investigated. The results show that LiFePO4/C nanocomposite with oxalic acid (oxalic acid: Fe2+= 0.75:1) and a small quantity of citric acid are single phase and deliver initial discharge capacity of 122.1 mAh/g at 1
C with little capacity loss up to 500 cycles at room temperature. The rate capability and cyclability are also outstanding
at elevated temperature. When charged/discharged at 60 °C, this materials present excellent initial discharge capacity of
148.8 mAh/g at 1 C, 128.6 mAh/g at 5 C, and 115.0 mAh/g at 10 C, respectively. The extraordinarily high performance of LiFePO4/C cathode materials can be exploited suitably for practical lithium-ion batteries. 相似文献
2.
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
3.
Liu Zhaolin Tay Siok Wei Hong Liang Lee Jim Yang 《Journal of Solid State Electrochemistry》2011,15(1):205-209
Olivine-type LiFePO4 composite materials for cathode material of the lithium-ion batteries were synthesized by using a sol-gel method and were
coated by a chemical deposition of silver particles. As-obtained LiFePO4/C-Ag (2.1 wt.%) composites were characterized by transmission electron microscopy (TEM), powder X-ray diffraction (XRD),
conductivity measurements, cyclic voltammetry, as well as galvanostatic measurements. The results revealed that the discharge
capacity of the LiFePO4/C-Ag electrode is 136.6 mAh/g, which is 7.6% higher than that of uncoated LiFePO4/C electrode (126.9 mAh/g). The LiFePO4/C coated by silver nanoparticles enhances the electrode conductivity and specific capacity at high discharge rates. The improved
capacity at high discharge rates may be attributed to increased electrode conductivity and the synergistic effect on electron
and Li+ transport after silver incorporation. 相似文献
4.
Weijia Zhou Wen He Zhengmao Li Hongshi Zhao Shunpu Yan 《Journal of Solid State Electrochemistry》2009,13(12):1819-1823
The yeast cells are adopted as a template and cementation agent to prepare LiFePO4/C with high surface area by co-precipitation and microwave processing. The electrochemical properties of the resultant products
are investigated. The synthesized LiFePO4/C is characterized by means of X-ray diffraction, transmission electron microscopy (TEM), Brunauer–Emmett–Teller method,
and battery test instrument. The LiFePO4/C particles with average size of 35-100 nm coated by porous carbon are observed by TEM. The LiFePO4/C, with the specific surface area of 98.3 m2/g, exhibits initial discharge specific capacity of 147 mAh/g and good cycle ability. The yeast cells as a template are used
to synthesize the precursor LiFePO4/cells compounds. In microwave heating process, the use of yeast cells as reducing matter and cementation agent results in
the enhancement of the electrochemical properties. 相似文献
5.
Seung-Ah Hong Agung Nugroho Su Jin Kim Jaehoon Kim Kyung Yoon Chung Byung-Won Cho Jeong Won Kang 《Research on Chemical Intermediates》2011,37(2-5):429-440
Nanosized lithium iron phosphate (LiFePO4) and transition metal oxide (MO, where M is Cu, Ni, Mn, Co, and Fe) particles are synthesized continuously in supercritical water at 25?C30?MPa and 400??C under various conditions for active material application in lithium secondary ion batteries. The properties of the nanoparticles, including crystallinity, particle size, surface area, and electrochemical performance, are characterized in detail. The discharge capacity of LiFePO4 was enhanced up to 140?mAh/g using a simple carbon coating method. The LiFePO4 particles prepared using supercritical hydrothermal synthesis (SHS) deliver the reversible and stable capacity at a current density of 0.1?C rate during ten cycles. The initial discharge capacity of the MO is in the range of 800?C1,100?mAh/g, values much higher than that of graphite. However, rapid capacity fading is observed after the first few cycles. The continuous SHS can be a promising method to produce nanosized cathode and anode materials. 相似文献
6.
Shixi Yu Shao Dan Guoen Luo Wei Liu Ying Luo Xiaoyuan Yu Yueping Fang 《Journal of Solid State Electrochemistry》2012,16(4):1675-1681
Olivine LiFePO4/C cathode materials for lithium ion batteries were synthesized using monodisperse polystyrene (PS) nano-spheres and other
carbon sources. The structure, morphology, and electrochemical performance of LiFePO4/C were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), galvanostatic charge–discharge tests,
electrochemical impedance spectroscopy (EIS) measurements, and Raman spectroscopy measurements. The results demonstrated that
LiFePO4/C materials have an ordered olivine-type structure with small particle sizes. Electrochemical analyses showed that the LiFePO4/C cathode material synthesized from 7 wt.% PS nano-spheres delivers an initial discharge capacity of 167 mAh g-1 (very close to the theoretical capacity of 170 mAh g-1) at 0.1 C rate cycled between 2.5 and 4.1 V with excellent capacity retention after 50 cycles. According to Raman spectroscopy
and EIS analysis, this composite had a lower I
D/I
G, sp
3/sp
2 peak ratio, charge transfer resistance, and a higher exchange current density, indicating an improved electrochemical performance,
due to the increased proportion of graphite-like carbon formed during pyrolysis of PS nano-spheres, containing functionalized
aromatic groups. 相似文献
7.
Xueliang Li Weidong Wang Chengwu Shi Hua Wang Yan Xing 《Journal of Solid State Electrochemistry》2009,13(6):921-926
A fast and convenient sol–gel route was developed to synthesize LiFePO4/C composite cathode material, and the sol–gel process can be finished in less than an hour. Polyethyleneglycol (PEG), d-fructose, 1-hexadecanol, and cinnamic acid were firstly introduced to non-aqueous sol–gel system as structure modifiers and
carbon sources. The samples were characterized by X-ray powder diffraction, field emission scanning electron microscopy, and
elemental analysis measurements. Electrochemical performances of LiFePO4/C composite cathode materials were characterized by galvanostatic charge/discharge and AC impedance measurements. The material
obtained using compound additives of PEG and d-fructose presented good electrochemical performance with a specific capacity of 157.7 mAh g−1 at discharge rate 0.2 C, and the discharge capacity remained about 153.6 mAh g−1 after 50 cycles. The results indicated that the improved electrochemical performance originated mainly from the microporous
network structure, well crystalline particles, and the increased electronic conductivity by proper carbon coating (3.11%). 相似文献
8.
Andrea Fedorková Renáta Oriňáková Andrej Oriňák Hans-Dieter Wiemhöfer Dušan Kaniansky Martin Winter 《Journal of Solid State Electrochemistry》2010,14(12):2173-2178
In this work, we studied LiFePO4 particles coated with thin films of highly conductive polypyrrole (PPy) and their electrochemical performance in cathode
layers of lithium cells. Carbon-free LiFePO4 particles were synthesized by a solvothermal method. Besides this, a part of the experiments were carried out on commercial
carbon-coated LiFePO4 for comparison. Polypyrrole coated LiFePO4 particles (PPy-LiFePO4) were obtained by a straightforward oxidative polymerization of dissolved pyrrole on LiFePO4 particles dispersed in water. The use of polyethylene glycol (PEG) as an additive during the polymerization was decisive
to achieve high electronic conductivities in the final cathode layers. The carbon-free and carbon-coated LiFePO4 particles were prepared with PPy and with PPy/PEG coating. The obtained PPy-LiFePO4 and PPy/PEG-LiFePO4 powders were characterized by SEM, EIS, cyclic voltammetry, and galvanostatic charge/discharge measurements in lithium-ion
cells with lithium metal as counter and reference electrode. Carbon-free LiFePO4 coated with PPy/PEG hybrid films exhibited very good electrode kinetics and a stable discharge capacity of 156 mAh/g at a
rate of C/10. Impedance measurements showed that the PPy/PEG coating decreases the charge-transfer resistance of the corresponding
LiFePO4 cathode material very effectively, which was attributed to a favorable mixed ionic and electronic conductivity of the PPy/PEG
coatings. 相似文献
9.
《Journal of Energy Chemistry》2017,26(3):564-568
Well-shaped and uniformly dispersed LiFePO_4 nanorods with a length of 400–500 nm and a diameter of about 100 nm, are obtained with participation of a proper amount of anion surfactant sodium dodecyl sulfonate(SDS) without any further heating as a post-treatment. The surfactant acts as a self-assembling supermolecular template, which stimulated the crystallization of LiFePO_4 and directed the nanoparticles growing into nanorods between bilayers of surfactant(BOS). LiFePO_4 nanorods with the reducing crystal size along the b axis shorten the diffusion distance of Li~+ extraction/insertion, and thus improve the electrochemical properties of LiFePO_4 nanorods. Such prepared LiFePO_4 nanorods exhibited excellent specific capacity and high rate capability with discharge capacity of 151 mAh/g, 122 mAh/g and 95 mAh/g at 0.1C, 1 C and 5 C, respectively. Such excellent performance of LiFePO_4 nanorods is supposed to be ascribed to the fast Li~+ diffusion velocity from reduced crystal size along the b axis and the well electrochemical conductivity. The structure, morphology and electrochemical performance of the samples were characterized by XRD, FE-SEM, HRTEM, charge/discharge tests, and EIS(electrochemical impedance spectra). 相似文献
10.
Core–shell LiFePO4/C composite was synthesized via a sol–gel method and doped by fluorine to improve its electrochemical performance. Structural
characterization shows that F− ions were successfully introduced into the LiFePO4 matrix. Transmission electron microscopy verifies that F-doped LiFePO4/C composite was composed of nanosized particles with a ~3 nm thick carbon shell coating on the surface. As a cathode material
for lithium-ion batteries, the F-doped LiFePO4/C nanocomposite delivers a discharge capacity of 162 mAh/g at 0.1 C rate. Moreover, the material also shows good high-rate
capability, with discharge capacities reaching 113 and 78 mAh/g at 10 and 40 C current rates, respectively. When cycled at
20 C, the cell retains 86% of its initial discharge capacity after 400 cycles, demonstrating excellent high-rate cycling performance. 相似文献
11.
《中国化学会会志》2018,65(8):977-981
LiFePO4/C and LiFe1–xNb xPO4/C composites were synthesized using a sol–gel method. The influence of niobium doping on the constitution, morphology, and electrochemical properties of the samples was studied in detail. X‐Ray diffraction patterns indicate that appropriate Nb doping does not alter seriously the structure of LiFePO4. Electrochemical characterization of the electrodes showed that the Li‐ion batteries based on LiFe1–xNb xPO4/C electrode exhibited better charge/discharge performance than those based on LiFePO4/C. The LiFe0.95Nb0.05PO4/C‐based cell had the specific capacity of 157, 121, and 85 mAh/g at 0.2, 2, and 5 C, respectively, in comparison with 126, 94, and 52 mAh/g for the LiFePO4/C cell. The results show that the addition of niobium promotes the electrochemical performance of the materials especially at high charge/discharge rates of the battery. 相似文献
12.
Junli Sun Lifang Jiao Xin Wei Wenxiu Peng Li Liu Huatang Yuan 《Journal of Solid State Electrochemistry》2010,14(4):615-619
This paper describes systematic studies on the effect of polyethylene glycol (PEG) molecular weight on the crystal structure
and particularly the electrochemical performance of LiV3O8. Scanning electron microscopy results indicate that after the decomposition of PEG, the structure of resultant products exhibits
differences in morphology (shape, particle size, and specific surface area). The electrochemical results show that LiV3O8 cathode material treated by PEG (mean molecular weight of 10,000) has greater initial discharge capacity and better cyclic
stability than other materials treated with PEG of different molecular weight. Its initial discharge capacity is 282.1 mAh
g−1 and maintains 222.2 mAh/g after 50 cycles in 0.5 C rates (150 mA g−1). 相似文献
13.
Preparation and Electrochemical Performance of V2O3-C Dual-Layer Coated LiFePO4 by Carbothermic Reduction of V2O5 下载免费PDF全文
The V2O3-C dual-layer coated LiFePO4 cathode materials with excellent rate capability and cycling stability were prepared by carbothermic reduction of V2O5. X-ray powder diffraction, elemental analyzer, high resolution transmission electron microscopy and Raman spectra revealed that the V2O3 phase co-existed with carbon in the coating layer of LiFePO4 particles and the carbon content reduced without graphitization degree changing after the carbothermic reduction of V2O5. The electrochemical measurement results indicated that small amounts of V2O3 improved rate capability and cycling stability at elevated temperature of LiFePO4/C cathode materials. The V2O3-C dual-layer coated LiFePO4 composite with 1wt% vanadium oxide delivered an initial specific capacity of 167 mAh/g at 0.2 C and 129 mAh/g at 5 C as well as excellent cycling stability. Even at elevated temperature of 55 oC, the specific capacity of 151 mAh/g was achieved at 1 C without capacity fading after 100 cycles. 相似文献
14.
H. Liu P. Zhang G. C. Li Q. Wu Y. P. Wu 《Journal of Solid State Electrochemistry》2008,12(7-8):1011-1015
Using the cheap raw materials lithium carbonate, iron phosphate, and carbon, LiFePO4/C composite can be obtained from the carbothermal reduction method. X-ray diffraction (XRD) and scanning electronic microscope (SEM) observations were used to investigate the structure and morphology of LiFePO4/C. The LiFePO4 particles were coated by smaller carbon particles. LiFePO4/C obtained at 750 °C presents good electrochemical performance with an initial discharge capacity of 133 mAh/g, capacity retention of 128 mAh/g after 20 cycles, and a diffusion coefficient of lithium ions in the LiFePO4/C of 8.80?×?10?13 cm2/s, which is just a little lower than that of LiFePO4/C obtained from the solid-state reaction (9.20?×?10?13 cm2/s) by using FeC2O4 as a precursor. 相似文献
15.
Jun Ma Baohua Li Hongda Du Chengjun Xu Feiyu Kang 《Journal of Solid State Electrochemistry》2012,16(1):1-8
Nanocrystalline LiFePO4 and LiFe0.97Sn0.03PO4 cathode materials were synthesized by an inorganic-based sol–gel route. The physicochemical properties of samples were characterized
by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and
elemental mapping. The doping effect of Sn on the electrochemical performance of LiFePO4 cathode material was extensively investigated. The results showed that the doping of tin was beneficial to refine the particle
size, increase the electrical conductivity, and facilitate the lithium-ion diffusion, which contributed to the improvement
of the electrochemical properties of LiFePO4, especially the high-rate charge/discharge performance. At the low discharge rate of 0.5 C, the LiFe0.97Sn0.03PO4 sample delivered a specific capacity of 158 mAh g−1, as compared with 147 mAh g−1 of the pristine LiFePO4. At higher C-rate, the doping sample exhibited more excellent discharge performance. LiFe0.97Sn0.03PO4 delivered specific capacity of 146 and 128 mAh g−1 at 5 C and 10 C, respectively, in comparison with 119 and 107 mAh g−1 for LiFePO4. Moreover, the doping of Sn did not influence the cycle capability, even at 10 C. 相似文献
16.
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
17.
Olivine LiFePO4 is challenged by its poor electronic and ionic conductivities for lithium-ion batteries. Polyethylene glycol (PEG) has been applied for LiFePO4 preparation by different research groups, but there is no consensus on the influence of the mean molecular weight of PEG on the structure and electrochemical performances of LiFePO4/C composites. In this work, LiFePO4/C composites were prepared by using micronsized FePO4·2H2O powder as starting material, PEG (mean molecular weight of 200, 400, 4000 or 10000) and citric acid as complex carbon source. The structure and electrochemical performances of LiFePO4/C composites would be decided considerably by the mean molecular weight of PEG, and the sample using PEG200 exhibited the least inter-particle agglomeration, the smallest charge transfer resistance and the highest discharge capacity. A probable growth mechanism is also proposed based on SEM images and electrochemical results: with the assistance of citric acid, PEG molecule with small molecular weight tends to cover one or only a few micron-sized FePO4·2H2O particles, significantly suppress the agglomeration of primary LiFePO4 particles and thus result in uniform particle-size distribution and carbon coating. 相似文献
18.
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
19.
Zhipeng Ma Guangjie Shao Xu Wang Jianjun Song Guiling Wang Tingting Liu 《Journal of Solid State Electrochemistry》2013,17(9):2409-2416
The olivine-type samarium-doped LiFe1 ? x Sm x PO4/C (x?=?0, 0.01, 0.02, 0.03, 0.04, and 0.05) composites were synthesized via liquid-phase precipitation reaction combined with the high-temperature solid-state method. The structure, morphology, and electrochemical performance of the samples were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, energy dispersive spectroscopy, galvanostatic charge–discharge, galvanostatic intermittent titration technique, and electrochemical impedance spectroscopy. The results showed that the small amount of Sm3+ ion-doped can keep the olivine microstructure of LiFePO4, modify the particle morphology, decrease polarization overpotential and charge transfer resistance, and enhance exchange current density, thus improve the electrochemical performance of the LiFePO4/C. However, the large doped content of Sm3+ ion can form more SmPO4, which can weaken the electrochemical performance of LiFePO4/C. Among all the doped samples, LiFe0.99Sm0.01PO4/C showed the best rate capacity, cycling stability, and low temperature performance. The LiFe0.99Sm0.01PO4/C sample exhibited the initial discharge capacity of 148.1, 133.4, 117.5, and 106.6 mAh g?1 at 1C, 2C, 5C, and 10C, respectively. In addition, the discharge capacity of the material was 94.8 mAh g?1 after 800 cycles at 10C. Moreover, the initial discharge capacity of 0.1C, 0.2C, 0.5C, and 1C were 104.4, 96.2, 53.9, and 50.8 mAh g?1 at ?20 °C. 相似文献
20.
Yang Yang Xiao-Zhen Liao Zi-Feng Ma Bao-Feng Wang Li He Yu-Shi He 《Electrochemistry communications》2009,11(6):1277-1280
A facile chemical polymerization method was applied to prepare LiFePO4/C-PPy composite using Fe(III)tosylate as oxidant. The as-prepared LiFePO4/C-PPy sample with PPy content of approximately 4 wt% showed great rate capability with a discharge capacity of 115 mAh/g at 20C. High temperate cycling performance of the LiFePO4/C-PPy sample was compared with bare LiFePO4/C at 5C charge–discharge rate at 55 °C. The LiFePO4/C-PPy cathode showed superior cycling stability with an initial capacity of 155 mAh/g. Ninety percentage of this initial capacity was retained after 300 cycles, compared to 40% of that of bare LiFePO4/C. The LiFePO4/C-PPy electrode showed stable discharge plateau voltage of 3.35–3.25 V vs. Li+/Li during long term cycling. The superior performance of the LiFePO4/C-PPy electrode was due to the enhanced electrical conductivity, negligible iron dissolution and alleviated electrode cracking contributed by PPy coating. 相似文献