共查询到20条相似文献,搜索用时 15 毫秒
1.
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
2.
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
3.
Sheng-Yao Chen Bo Gao Ling-Hao Su Chang-Huan Mi Xiao-Gang Zhang 《Journal of Solid State Electrochemistry》2009,13(9):1361-1366
LiFePO4/C composites were synthesized by pyrolysis of LiFePO4/polypyrrole (PPy), which was obtained by an in situ chemical polymerization involving pyrrole monomer and hydrothermal synthesis LiFePO4. All samples were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy,
cyclic voltammetry, and galvanostatic charge–discharge techniques. The results showed the LiFePO4/C sintered at 800 °C containing 2.8 wt.% carbon exhibited a higher discharge capacity of 49.6 mAh·g−1 at 0.1 C, and bare LiFePO4 only delivered 11.6 mAh·g−1 in 2 M LiNO3 aqueous electrolyte. The possible reason for the improvement of electrochemical performance was discussed and could be attributed
to the formation of aromatic compounds during the carbonization of PPy. 相似文献
4.
An Yongxin Cheng Xinqun Zuo Pengjian Liao Lixia Yin Geping 《Journal of Solid State Electrochemistry》2012,16(1):383-389
A new kind of polymer electrolyte is prepared from N-methyl-N-propylpiperidinium bis (trifluoromethanesulfonyl) imide (PP1.3TFSI), polyethylene oxide (PEO), and lithium bis (trifluoromethanesulfonyl)
imide (LiTFSI). IR and X-ray diffraction results demonstrate that the addition of ionic liquid decreases the crystallization
of PEO. Thermal and electrochemical properties have been tested for the solid polymer electrolytes, the addition of the room
temperature molten salt PP1.3TFSI to the conventional P(EO)20LiTFSI polymer electrolyte leads to the improvement of the thermal stability and the ionic conductivity (x = 1.27, 2.06 × 10−4 S cm−1 at room temperature), and the reasonable lithium transference number is also obtained. The Li/LiFePO4 cell using this polymer electrolyte shows promising reversible capacity, 120 mAh g−1 at room temperature and 164 mAh g−1 at 55 °C. 相似文献
5.
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
6.
Synthesis and electrochemical properties of K-doped LiFePO4/C composite as cathode material for lithium-ion batteries 总被引:1,自引:0,他引:1
Xuesong Fang Jing Li Kelong Huang Suqin Liu Chenghuan Huang Shuxin Zhuang Jinbao Zhang 《Journal of Solid State Electrochemistry》2012,16(2):767-773
Li1 − x
K
x
FePO4/C (x = 0, 0.03, 0.05, and 0.07) composites were synthesized at 700 °C in an argon atmosphere by carbon thermal reduction method.
Based on X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analysis, the composite was
ultrafine sphere-like particles with 100–300 nm size, and the lattice structure of LiFePO4 was not destroyed by K doping, while the lattice volume was enlarged. The electrochemical properties were investigated by
four-point probe conductivity measurements, galvanostatic charge and discharge tests, cyclic voltammetry and electrochemical
impedance spectroscopy. The results indicated that the capacity performance at high rate and cyclic stability were improved
by doping an appropriate amount of K, which might be ascribed to the fact that the doped K ion expands Li ion diffusion pathway.
Among the doped materials, the Li0.97K0.03FePO4/C samples exhibited the best electrochemical activity, with the initial discharge capacity of 153.7 mAh g−1 at 0.1 C and the capacity retention rate of about 92% after 50 cycles at above 1 C, 11% higher than undoped sample. Remarkably,
it still showed good cycle retention at a high current rate of 10 C. 相似文献
7.
Spinel Li4Ti5 − x
Zr
x
O12/C (x = 0, 0.05) were prepared by a solution method. The structure and morphology of the as-prepared samples were characterized
by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The electrochemical performances
including charge–discharge (0–2.5 V and 1–2.5 V), cyclic voltammetry, and ac impedance were also investigated. The results
revealed that the Li4Ti4.95Zr0.05O12/C had a relatively smaller particle size and more regular morphology than that of Li4Ti5O12/C. Zr4+ doping enhanced the ability of lithium-ion diffusion in the electrode. It delivered a discharge capacity 289.03 mAh g−1 after 50 cycles for the Zr4+-doped Li4Ti5O12/C while it decreased to 264.03 mAh g−1 for the Li4Ti5O12/C at the 0.2C discharge to 0 V. Zr4+ doping did not change the electrochemical process, instead enhanced the electronic conductivity and ionic conductivity. The
reversible capacity and cycling performance were effectively improved especially when it was discharged to 0 V. 相似文献
8.
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
9.
Liu Zhiqiang Kang Xueya Li Chengfeng Hua Ning Wumair Tuerdi Han Ying 《Journal of Solid State Electrochemistry》2012,16(5):1917-1923
The electrochemical performance of Li3V2(PO4)3/C was investigated at various low temperatures in the electrolyte 1.0 mol dm−3 LiPF6/ethyl carbonate (EC)+diethyl carbonate (DEC)+dimethyl carbonate (DMC) (volume ratio 1:1:1). The stable specific discharge
capacity is 125.4, 122.6, 119.3, 116.6, 111.4, and 105.7 mAh g−1 at 26, 10, 0, −10, −20, and −30 °C, respectively, in the voltage range of 2.3–4.5 V at 0.2 C rate. When the temperature decreases
from −30 to −40 °C, there is a rapid decline in the capacity from 105.7 to 69.5 mAh g−1, implying that there is a nonlinear relationship between the performance and temperature. With temperature decreasing, R
ct (corresponding to charge transfer resistance) increases rapidly, D (the lithium ion diffusion coefficients) decreases sharply, and the performance of electrolyte degenerates obviously, illustrating
that the low-temperature electrochemical performance of Li3V2(PO4)3/C is mainly limited by R
ct, D
Li, and electrolyte. 相似文献
10.
The electrochemical performances of lithium iron phosphate (LiFePO4), hard carbon (HC) materials, and a full cell composed of these two materials were studied. Both positive and negative electrode
materials and the full cell were characterized by scanning electron microscopy, transmission electron microscopy, charge–discharge
tests, and alternating current (a.c.) impedance techniques. Experimental results show that the LiFePO4/HC full cell exhibits a gradually decreased cell voltage, and it is capable of delivering a reversible discharge capacity
of 122.1 mAh g−1 at 0.2-C rate. At the higher rate of 10 C, the efficiency of the full cell remains almost unchanged from that of 0.2 C. Furthermore,
the LiFePO4/HC battery demonstrated a long life of 2,450 cycles with 40% of capacity change at a 10-C high rate. The internal resistance
of the full cell is rather low as it is revealed from a.c. impedance measurements. These properties make the LiFePO4/HC battery an attractive option for high rate and long cycle life power applications. 相似文献
11.
Christie Thomas Cherian M. V. Reddy G. V. Subba Rao Chorng Haur Sow B. V. R. Chowdari 《Journal of Solid State Electrochemistry》2012,16(5):1823-1832
Sol–gel auto-combustion method is adopted to prepare solid solutions of nano-crystalline spinel oxides, (Ni1 − x
Zn
x
)Fe2O4 (0 ≤ x ≤ 1).The phases are characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy, selected
area electron diffraction, and Brunauer–Emmett–Teller surface area. The cubic lattice parameters, calculated by Rietveld refinement
of XRD data by taking in to account the cationic distribution and affinity of Zn ions to tetrahedral sites, show almost Vegard’s
law behavior. Galvanostatic cycling of the heat-treated electrodes of various compositions are carried in the voltage range
0.005–3 V vs. Li at 50 mAg−1 up to 50 cycles. Phases with high Zn content x ≥ 0.6 showed initial two-phase Li-intercalation in to the structure. Second-cycle discharge capacities above 1,000 mAh g−1 are observed for all x. However, drastic capacity fading occurs in all cases up to 10–15 cycles. The capacity fading between 10 and 50 cycles is
found to be greater than 52% for x ≤ 0.4 and for x = 0.8. For x = 0.6 and x = 1, the respective values are 40% and 18% and a capacity of 570 and 835 mAh g−1 is retained after 50 cycles. Cyclic voltammetry and ex situ transmission electron microscopy data elucidate the Li-cycling
mechanism involving conversion reaction and Li–Zn alloying–dealloying reactions. 相似文献
12.
Lilong Xiong Youlong Xu Cheng Zhang Zhengwei Zhang Jiebin Li 《Journal of Solid State Electrochemistry》2011,15(6):1263-1269
Ti-doped spinel LiMn2O4 is synthesized by solid-state reaction. The X-ray photoelectron spectroscopy and X-ray diffraction analysis indicate that
the structure of the doped sample is Li( Mn3 + Mn1 - x 4 + Tix4 + )O4 {\hbox{Li}}\left( {{\hbox{M}}{{\hbox{n}}^{3 + }}{\hbox{Mn}}_{1 - x\,}^{4 + }{\hbox{Ti}}_x^{4 + }} \right){\hbox{O}}{}_4 . The first principle-based calculation shows that the lattice energy increases as Ti doping content increases, which indicates
that Ti doping reinforces the stability of the spinel structure. The galvanostatic charge–discharge results show that the
doped sample LiMn1.97Ti0.03O4 exhibits maximum discharge capacity of 135.7 mAh g−1 (C/2 rate). Moreover, after 70 cycles, the capacity retention of LiMn1.97Ti0.03O4 is 95.0% while the undoped sample LiMn2O4 shows only 84.6% retention under the same condition. Additionally, as charge–discharge rate increases to 12C, the doped sample
delivers the capacity of 107 mAh g−1, which is much higher than that of the undoped sample of only 82 mAh g−1. The significantly enhanced capacity retention and rate capability are attributed to the more stable spinel structure, higher
ion diffusion coefficient, and lower charge transfer resistance of the Ti-doped spinel. 相似文献
13.
Manjunatha H. Venkatesha T. V. Suresh G. S. 《Journal of Solid State Electrochemistry》2012,16(5):1941-1952
A study of the electrochemical behavior of LiMnPO4 prepared by RAPET method in different aqueous electrolytes using cyclic voltammetry (CV), galvanostatic charge–discharge
experiments, and electrochemical impedance spectroscopy is reported. CV peak current is proportional to the square root of
scan rate under 0.2 mV s−1. The system satisfied the required conditions for a reversible system with a resistive behavior. LiMnPO4 was found to undergo proton insertion at lower concentrations of electrolyte. At higher concentrations or saturated solutions
of electrolytes, lithium insertion/de-insertion becomes the main reaction though the effect of proton insertion/de-insertion
reaction cannot be ignored. Electrochemical insertion/de-insertion of lithium in LiMnPO4 was studied using EIS technique. The kinetic parameter, charge transfer resistance (R
ct), obtained by simulating the experimental impedance data with an equivalent circuit showed a minimum at the potential close
to the CV peak potential. The cell LiTi2(PO4)3/5 M LiNO3/LiMnPO4 delivers a discharge capacity of 84 mAh g−1 in the first cycle at an applied current of 0.2 mA cm−2 and it retains its initial capacity over 50 cycles with good rate capability. 相似文献
14.
Hong Tang Xiao-Dong Guo Ben-He Zhong Heng Liu Yan Tang Rui Xu Long-Yan Li 《Journal of Solid State Electrochemistry》2012,16(4):1537-1543
Hybrid materials xLiFePO4·(1 − x)Li3V2(PO4)3 were synthesized by sol–gel method, with phenolic resin as carbon source and chelating agent, methylglycol as surfactant.
The crystal structure, morphology and electrochemical performance of the prepared samples were investigated by X-ray diffraction
(XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), galvanostatic charge–discharge test and particle size
analysis. The results show that LiFePO4 and Li3V2(PO4)3 co-exist in hybrid materials, but react in single phase. Compared with individual LiFePO4 and Li3V2(PO4)3 samples, hybrid materials have smaller particle size and more uniform grain distribution. This structure can facilitate Li
ions extraction and insertion, which greatly improves the electrochemical properties. The sample 0.7LiFePO4·0.3Li3V2(PO4)3 retains the advantages of LiFePO4 and Li3V2(PO4)3, obtaining an initial discharge capacity of 166 mA h/g at 0.1 C rate and 109 mA h/g at 20 C rate, with a capacity retention
rate of 73.3% and an excellent cycle stability. 相似文献
15.
B. Das M. V. Reddy G. V. Subba Rao B. V. R. Chowdari 《Journal of Solid State Electrochemistry》2011,15(2):259-268
Nano-composites of SnO(V2O3)
x
(x = 0, 0.25, and 0.5) and SnO(VO)0.5 are prepared from SnO and V2O3/VO by high-energy ball milling (HEB) and are characterized by X-ray diffraction (XRD), scanning electron microscopy, and
high-resolution transmission electron microscopy techniques. Interestingly, SnO and SnO(VO)0.5 are unstable to HEB and disproportionate to Sn and SnO2, whereas HEB of SnO(V2O3)
x
gives rise to SnO2.VO
x
. Galvanostatic cycling of the phases is carried out at 60 mA g−1 (0.12 C) in the voltage range 0.005–0.8 V vs. Li. The nano-SnO(V2O3)0.5 showed a first-charge capacity of 435 (±5) mAh g−1 which stabilized to 380 (±5) mAh g−1 with no noticeable fading in the range of 10–60 cycles. Under similar cycling conditions, nano-SnO (x = 0), nano-SnO(V2O3)0.25, and nano-SnO(VO)0.5 showed initial reversible capacities between 630 and 390 (±5) mAh g−1. Between 10 and 50 cycles, nano-SnO showed a capacity fade as high as 59%, whereas the above two VO
x
-containing composites showed capacity fade ranging from 10% to 28%. In all the nano-composites, the average discharge potential
is 0.2–0.3 V and average charge potential is 0.5–0.6 V vs. Li, and the coulombic efficiency is 96–98% after 10 cycles. The
observed galvanostatic cycling, cyclic voltammetry, and ex situ XRD data are interpreted in terms of the alloying–de-alloying
reaction of Sn in the nano-composite “Sn-VO
x
-Li2O” with VO
x
acting as an electronically conducting matrix. 相似文献
16.
Jun Ma Baohua Li Hongda Du Chengjun Xu Feiyu Kang 《Journal of Solid State Electrochemistry》2012,16(4):1353-1362
An inorganic and non-toxic compounds combination of FeCl2·4H2O, Li2CO3 and H3PO4 was chosen to synthesize homogeneous nano-structured LiFePO4/C composite material via a simplified sol–gel route. The dependency of the physicochemical properties and the corresponding
electrochemical responses on the residual carbon content were investigated in details. Rietveld refinement of X-ray diffraction
measurement and X-ray photoelectron spectroscopy analysis confirmed the feasibility of preparing pure LiFePO4 phase via this approach. With increasing amount of residual carbon, the particles size gradually decreased and the bulk electrical
conductivity monotonically increased. However, the higher level of residual carbon would bring disadvantageous impact on the
lithium ion diffusion. Due to high electrical conductivity, controlled particle size and suitable microstructure, the sample
with 4.5 wt.% residual carbon exhibited stable cycling performance and delivered high discharge capacity of 163, 119 and 108 mA h g−1 at 0.1 C, 5 C and 10 C, respectively. 相似文献
17.
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
18.
Development of activated carbon from vine shoots by physical and?chemical activation methods. Some insight into activation mechanisms 总被引:1,自引:0,他引:1
M. Ruiz-Fernández M. Alexandre-Franco C. Fernández-González V. Gómez-Serrano 《Adsorption》2011,17(3):621-629
Activated carbons (ACs) are prepared from vine shoots (VS) by the method of physical activation in air, CO2 and steam atmospheres and by the method of chemical activation with H3PO4, ZnCl2 and KOH aqueous solutions. The ACs were characterized texturally by N2 adsorption at −196 °C, mercury porosimetry, and density measurements. The method of chemical activation has been proved to
be more effective than the method of physical activation to prepare ACs with a well-developed porosity. ACs with high micro-
and mesopore volumes are prepared with ZnCl2 and H3PO4. Using ZnCl2, the volume of micropores is 0.62 cm3 g−1 and the volume of mesopores is 0.81 cm3 g−1. A greater development of macroporosity is obtained by KOH activation. The volume of macropores is as high as 1.13 cm3 g−1 for the resulting AC. Yield of the process of preparation of the ACs is low for the method of chemical activation. Some insights
into the performance of the activating agents in the activation process are provided. 相似文献
19.
Chun-Chen Yang Ying-Chih Chen Zuo-Yu Lian Tzong-Horng Liou Jeng-Ywan Shih 《Journal of Solid State Electrochemistry》2012,16(5):1815-1821
This study reports on the preparation of a composite polymer electrolyte for secondary lithium-ion battery. Poly(vinylidiene
fluoride-hexafluoropropylene) (P(VDF-HFP)) was used as the polymer host, and mesoporous SBA-15 (silica) ceramic fillers used
as the solid plasticizer were added into the polymer matrix. The SBA-15 fillers with mesoporous structure and high specific
surface can trap more liquid electrolytes to enhance the ionic conductivity. The ionic conductivity of P(VDF-HFP)/SBA-15 composite
polymer electrolytes was in the order of 10−3 S cm−1 at room temperature. The characteristic properties of the composite polymer membranes were examined by using FTIR spectroscopies,
scanning electron microscopy (SEM), and an AC impedance method. For comparison, the LiFePO4/Li composite batteries with a conventional microporous polyethylene (PE) separator and pure P(VDF-HFP) polymer membrane were
also prepared and studied. As a result, the LiFePO4/Li composite battery comprised the P(VDF-HFP)/10 wt.% m-SBA-15 composite polymer electrolyte, which achieves an optimal discharge
capacity of 88 mAh g−1 at 20 C rate with a high coulomb efficiency of 95%. It is demonstrated that the P(VDF-HFP)/m-SBA-15 composite membrane exhibits
as a good candidate for application to LiFePO4 polymer batteries. 相似文献
20.
Feng Yu Jingjie Zhang Yanfeng Yang Guangzhi Song 《Journal of Solid State Electrochemistry》2010,14(5):883-888
Composite Li3V2(PO4)3/C cathode material can be synthesized by spray-drying and carbothermal method. The monoclinic-phase Li3V2(PO4)3/C was prepared with the process of double spray drying at 260 °C and subsequent heat treatment at 750 °C for 12 h. The results
indicate that the Li3V2(PO4)3/C presents large reversible discharge capacity of 121.9 mA h g−1 and charge capacity of 131.8 mA h g−1 at the current density of C/5, good rate capability with 61.1 mA h g−1 at 20C, and excellent capacity retention rate close to 100% at various current densities in the region of 3.0–4.3 V. 相似文献