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1.
DENG Fei ZENG XieRong ZOU JiZhao HUANG JianFeng SHENG HongChao XIONG XinBo QIAN HaiXia LI XiaoHua 《科学通报(英文版)》2011,56(17):1832-1835
One of the most important factors that limits the use of LiFePO 4 as cathode material for lithium ion batteries is its low electronic conductivity.In order to solve this problem,LiFePO 4 in situ vapor-grown carbon fiber (VGCF) composite cathode material has been prepared in a single step through microwave pyrolysis chemical vapor deposition.The phase,microstructure,and electrochemical performance of the composites were investigated.Compared with the cathodes without in situ VGCF,the initial discharge capacity of the composite electrode increases from 109 to 144 mA h g-1 at a 0.5-C rate,and the total electric resistance decreases from 538 to 66.The possible reasons for these effects are proposed. 相似文献
2.
We reconstruct the three-dimensional microstructure of a cathode from a commercial LiCoO2 Lithium-ion battery with an adapted simulated annealing approach. The real size distribution curve of LiCoO2 particles is applied to regulate the reconstruction process. By discretizing a 40 μm×40 μm×40 μm cathode volume with 8000000 numerical cubes, the cathode involving three individual phases: (1) LiCoO2 as active material, (2) pores or electrolyte, and (3) additives (polyvinylidene fluoride+carbon black) is reconstructed. Characterization of the reconstructed cathode gives important structural and transport properties including volume-specific surface area between phases, tortuosity and geometrical connectivity of individual phase. 相似文献
3.
Four types of TiO 2 thin-film electrodes were fabricated from TiO 2 and Fe(III) doped TiO 2 sols using a layer-by-layer dip-coating technique. Electrodes fabricated were TF (pure TiO 2 surface, Fe(III)-TiO 2 bottom layer), FT (Fe(III)-TiO 2 surface, pure TiO 2 bottom layer), TT (both layers pure TiO 2 ) and FF (both layers Fe(III)-TiO 2 ). The photoelectrochemical behavior of these electrodes was characterized using linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and steady-state photocurrent measurements in aqueous 0.1 mol L –1 NaNO 3 containing varying concentrations of glucose or potassium hydrogen phthalate (KHP). EIS and LSV results revealed that exciton separation efficiency followed the sequence of TF﹥TT﹥FT > FF. Under a constant potential of +0.3 V, steady-state photocurrent profiles were recorded with varying organic compound concentrations. The TF electrode possessed the greatest photocatalytic capacity for oxidizing glucose and KHP, and possessed a KHP anti-poisoning effect. Enhanced photoelectrochemical performance of the TF electrode was attributed to effective exciton separation because of the layered TF structure. 相似文献
4.
XU ShengXian WU XueFei WU QingYin & YAN WenFu Department of Chemistry Zhejiang University Hangzhou China School of Chemistry Chemical Engineering Jiangxi Science Technology Teachers’ College Nanchang State Key Laboratory of Inorganic Synthesis Preparative Chemistry Jilin University Changchun China Received October accepted January 《科学通报(英文版)》2011,56(25):2679-2682
The ruthenium-substituted polyoxometallic acid H6 [Ru(H2O)FeW 11O39 ]·18H2O was synthesized by stepwise acidification and stepwise addition of solutions of the component elements, and an ion-exchange-cooling method. The product was characterized using inductively coupled plasma spectrometry (ICP), Infrared Spectroscopy (IR), Ultraviolet Spectroscopy (UV), and X-ray diffraction (XRD). The results show that this complex has the Keggin structure. The determination of the thermal stability and proton conductivi... 相似文献
5.
Electrochemical characterization of MnO2 as the cathode material for a high voltage hybrid capacitor 下载免费PDF全文
Manganese dioxide (MnO2) was prepared using the ultrasonic method. Its electrochemical performance was evaluated as the cathode material for a high voltage hybrid capacitor. And the specific capacitance of the MnO2 electrode reached 240 F·g-1. The new hybrid capacitor was constructed, combining A1/Al2O3 as the anode and MnO2 as the cathode with electrolyte for the aluminum electrolytic capacitor to solve the problem of low working voltage of a supercapacitor unit. The results showed that the hybrid capacitor had a high energy density and the ability of quick charging and discharging according to the electrochemical performance test. The capacitance was 84.4 μF, and the volume and mass energy densities were greatly improved compared to those of the traditional aluminum electrolytic capacitor of 47 μF. The analysis of electrochemical impedance spectroscopy (EIS) showed that the hybrid capacitor had good impedance characteristics. 相似文献
6.
Carbon-coated LiFePO4 hollow nanofibers as cathode materials for Li-ion batteries were obtained by coaxial electrospinning. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller specific surface area analysis, galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS) were employed to investigate the crystalline structure, morphology, and electrochemical performance of the as-prepared hollow nanofibers. The results indicate that the carbon-coated LiFePO4 hollow nanofibers have good long-term cycling performance and good rate capability: at a current density of 0.2C (1.0C = 170 mA·g-1) in the voltage range of 2.5–4.2 V, the cathode materials achieve an initial discharge specific capacity of 153.16 mAh·g-1 with a first charge–discharge coulombic efficiency of more than 97%, as well as a high capacity retention of 99% after 10 cycles; moreover, the materials can retain a specific capacity of 135.68 mAh·g-1, even at 2C. 相似文献
7.
XI Jingyu MA Xiaomei CUI Mengzhong HUANG Xiaobin ZHENG Zhen & TANG Xiaozhen . School of Chemistry Chemical Technology Shanghai Jiao Tong University Shanghai China . School of Chemistry Chemical Technology Qingdao University Qingdao China Correspondence should be addressed to Tang Xiaozhen 《科学通报(英文版)》2004,49(8):785-789
Allsolid-statelithiumpolymerbatteriesmaybeoneofthebestchoicesforelectrochemicalpowersourceofthefuturecharacterizedbyitshighenergydensities,goodcyclability,reliabilityandsafety[1,2].PEO-LiXbasedpoly-merelectrolyteshadreceivedextensiveattention[4,5],foritspotentialcapabilitytobeusedascandidatematerialforthetraditionalliquidelectrolytes,sinceWrightetal.foundthatthecomplexofPEOandalkalinesaltshadtheabilityofionicconductivityin1973[3].ThegeneralconceptofthetransportofLi+inthepolymerelectrolytewa… 相似文献
8.
The electro-deoxidation of V2O3 precursors was studied. Experiments were carried out with a two-terminal electrochemical cell, which was comprised of a molten
electrolyte of CaCl2 and NaCl with additions of CaO, a cathode of compact V2O3, and a graphite anode under the potential of 3.0 V at 1173 K. The phase constitution and composition as well as the morphology
of the samples were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). 3 g of V2O3 could be converted to vanadium metal powder within the processing time of 8 h. The kinetic pathway was investigated by analyzing
the product phase in samples prepared at different reduction stages. CaO added in the reduction path of V2O3 formed the intermediate product CaV2O4. 相似文献
9.
I-doping of anodized TiO<Subscript>2</Subscript> nanotubes using an electrochemical method 总被引:1,自引:0,他引:1
In order to obtain TiO2 with high photocatalytic activity, a cathode reduction was used to dope I7+ and I5+ into TiO2 nanotubes of anodized Ti in C2H2O4•2H2O + NH4F electrolyte. SEM images show that the anodization method integrated the preparation with the doping process, which for nonmetals-doping is advantageous to maintain the morphological integrity of TiO2 nanotubes. I7+-I5+-doping enhances the UV response of TiO2 and result in a red-shift. Under UV/visible irradiation, a I7+-I5+-doped sample (400°C) showed the highest Iph and photocatalytic efficiency. A part of I– in the I7+-I5+-doped sample is involved in the UV response, the red-shift and the higher Iph. 相似文献
10.
A new guanidinium-based ionic liquid (IL) was investigated as a novel electrolyte for a lithium rechargeable battery. The
viscosity, conductivity, lithium redox behavior, and charge-discharge characteristics of the lithium rechargeable batteries
were investigated for the IL electrolyte with 0.3 mol kg−1 lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt. Li/LiFePO4 cells incorporating the IL electrolyte without additives showed good cycle properties at a charge-discharge current rate
of 0.1 C, and exhibited good rate capabilities in the presence of a mass fraction of 10% vinylene carbonate or gamma-butyrolactone. 相似文献
11.
The conductivity of MnCo2O4 spinel, the best route to form the MnCo2O4 protective coating applied by the sol-gel process, and its effect on the intermediate temperature oxidation behavior of SUS
430 alloy, a typical material for the interconnect of solid oxide fuel cell (SOFC), was investigated. The phase structure
and surface morphology of the coating and surface oxides were characterized by XRD, SEM and EDS; the “4-probe” method was
employed to determine the conductivity of MnCo2O4 spinel and the area specific resistance (ASR) of the surface oxides. The conductivity of MnCo2O4 spinel is excellent, which is 2 orders of magnitude better than that of MnCr2O4 spinel. Long-term thermally cyclic oxidation at 750°C in SOFC cathode atmosphere and ASR measurement have shown that calcined
in reducing atmosphere followed by pre-oxidation in the air is the best technique for forming the MnCo2O4 protective coating, which enhances the oxidation resistance, and improves the electrical conductivity and adherence of coated
SUS 430 alloy significantly. As a result, the MnCo2O4 spinel is the most potential candidate for SOFC metallic interconnect protective coating application. 相似文献
12.
Lithium-ion full cell with high energy density using nickel-rich LiNi0.8Co0.1Mn0.1O2 cathode and SiO-C composite anode 下载免费PDF全文
A high-energy-density Li-ion battery with excellent rate capability and long cycle life was fabricated with a Ni-rich layered LiNi0.8Mn0.1Co0.1O2 cathode and SiO-C composite anode. The LiNi0.8Mn0.1Co0.1O2 and SiO-C exhibited excellent electrochemical performance in both half and full cells. Specifically, when integrated into a full cell configuration, a high energy density (280 Wh·kg-1) with excellent rate capability and long cycle life was attained. At 0.5C, the full cell retained 80% of its initial capacity after 200 charge/discharge cycles, and 60% after 600 cycles, indicating robust structural tolerance for the repeated insertion/extraction of Li+ ions. The rate performance showed that, at high rate of 1C and 2C, 96.8% and 93% of the initial capacity were retained, respectively. The results demonstrate strong potential for the development of high energy density Li-ion batteries for practical applications. 相似文献
13.
A gas diffusion electrode (air electrode) with a high current efficiency of electro-synthesizing H2O2 using O2 in air was prepared. The several systems with air electrode as cathode of electro-synthesizing H2O2 on the reaction spot for degrading aniline in aqueous—electro-Fenton system, photo-excitation electro-H2O2 system and photo-electro-Fenton system, were developed. The rates of decomposition of H2O2 and mineralization of aniline were experimentally measured respectively under different conditions, and the results indicated
there has an excellent parallel relation between decomposition rate of H2O2 and mineralization rate of aniline. Especially, photo-electro-Fenton system, where H2O2 is decomposed the fastest, is the best system of oxidizing and degrading organic toxicants. Compared photo-electro-Fenton
system with photo-Fenton system, important role is revealed in the interface of air electrode. In this paper, the mineralization
mechanism of aniline in the photo-electro-Fenton system was also discussed.
Foundation item: Supported by the National Natural Science Foundation of China (200710026) and Foundation of Environmental Sciences Academy
of Jiangsu Province.
Biography: Cao xiao-yu (1979-), male, Master candidate, research direction: Electrochemistry 相似文献
14.
Low temperature performance of LiFePO4/C cathode was remarkably improved by slight Mn-substitution. Electrochemical measurements showed that about 95% of the discharge
capacity of LiFe0.98Mn0.02PO4/C cathode at 20°C was obtained at 0°C, compared to 85% of that of LiFePO4/C cathode. The LiFe0.98Mn0.02PO4/C sample also presented enhanced rate performance at −20°C with the discharge capacities of 124.4 mA h/g (0.1C), 99.8 mA
h/g (1C), 80.7mAh/g (2C) and 70 mA h/g (5C), respectively, while pristine LiFePO4/C only delivered capacities of 120.5 mA h/g (0.1C), 90.7 mA h/g (1C), 70.4 mA h/g (2C) and 52.2 mA h/g (5C). Cyclic voltammetry
measurements demonstrated an obvious improvement of the lithium insertion-extraction process of the LiFePO4/C cathode by slight Mn-substitution. The results of FSEM observation and electrical conductivity measurement indicated that
slight Mn-substitution minimized the particle size of LiFe0.98Mn0.02PO4/C and also obviously improved the electrical conductivity of the compound, thus obviously enhances the interface reaction
process on the cathode. 相似文献
15.
Electrical conductivity optimization of the Na3AlF6-Al2O3-Sm2O3 molten salts system for Al-Sm intermediate binary alloy production 下载免费PDF全文
Chun-fa Liao Yun-fen Jiao Xu Wang Bo-qing Cai Qiang-chao Sun Hao Tang 《矿物冶金与材料学报》2017,24(9):1034-1042
Metal Sm has been widely used in making Al-Sm magnet alloy materials. Conventional distillation technology to produce Sm has the disadvantages of low productivity, high costs, and pollution generation. The objective of this study was to develop a molten salt electrolyte system to produce Al-Sm alloy directly, with focus on the electrical conductivity and optimal operating conditions to minimize the energy consumption. The continuously varying cell constant (CVCC) technique was used to measure the conductivity for the Na3AlF6-AlF3-LiF-MgF2-Al2O3-Sm2O3 electrolysis medium in the temperature range from 905 to 1055℃. The temperature (t) and the addition of Al2O3 (W(Al2O3)), Sm2O3 (W(Sm2O3)), and a combination of Al2O3 and Sm2O3 into the basic fluoride system were examined with respect to their effects on the conductivity (κ) and activation energy. The experimental results showed that the molten electrolyte conductivity increases with increasing temperature (t) and decreases with the addition of Al2O3 or Sm2O3 or both. We concluded that the optimal operation conditions for Al-Sm intermediate alloy production in the Na3AlF6-AlF3-LiF-MgF2-Al2O3-Sm2O3 system are W(Al2O3) + W(Sm2O3)=3wt%, W(Al2O3):W(Sm2O3)=7:3, and a temperature of 965 to 995℃, which results in satisfactory conductivity, low fluoride evaporation losses, and low energy consumption. 相似文献
16.
Electrochemical performance of a nickel-rich LiNi<Subscript>0.6</Subscript>Co<Subscript>0.2</Subscript>Mn<Subscript>0.2</Subscript>O<Subscript>2</Subscript> cathode material for lithium-ion batteries under different cut-off voltages 下载免费PDF全文
A spherical-like Ni0.6Co0.2Mn0.2(OH)2 precursor was tuned homogeneously to synthesize LiNi0.6Co0.2Mn0.2O2 as a cathode material for lithium-ion batteries. The effects of calcination temperature on the crystal structure, morphology, and the electrochemical performance of the as-prepared LiNi0.6Co0.2Mn0.2O2 were investigated in detail. The as-prepared material was characterized by X-ray diffraction, scanning electron microscopy, laser particle size analysis, charge-discharge tests, and cyclic voltammetry measurements. The results show that the spherical-like LiNi0.6Co0.2Mn0.2O2 material obtained by calcination at 900℃ displayed the most significant layered structure among samples calcined at various temperatures, with a particle size of approximately 10 μm. It delivered an initial discharge capacity of 189.2 mAh·g-1 at 0.2C with a capacity retention of 94.0% after 100 cycles between 2.7 and 4.3 V. The as-prepared cathode material also exhibited good rate performance, with a discharge capacity of 119.6 mAh·g-1 at 5C. Furthermore, within the cut-off voltage ranges from 2.7 to 4.3, 4.4, and 4.5 V, the initial discharge capacities of the calcined samples were 170.7, 180.9, and 192.8 mAh·g-1, respectively, at a rate of 1C. The corresponding retentions were 86.8%, 80.3%, and 74.4% after 200 cycles, respectively. 相似文献
17.
XiaoQin Xiong Yan Jiang ShengAn Xia WuXing Zhang LiXia Yuan ShanTang Liu YunHui Huang 《科学通报(英文版)》2010,55(30):3419-3423
Oxalic-acid-based co-precipitation method was employed to prepare LiNi2/3Mn1/3O2 sample with a high-ordered structure. Li+, Ni2+ and Mn2+ acetates were used as starting materials. The influence of the amount of lithium source in the starting materials on Li+ content, disorder of Li+-Ni2+ ions, and electrochemical performance has been investigated. Rietveld refinement shows that the sample prepared with 20% excess Li-source in the starting materials exhibits a perfect ordered structure. A specific discharge capacity is as high as 172 mAh/g at C/20 in the voltage range of 4.35–2.7 V. However, the cyclability is not satisfactory: about 25.3% fade in capacity was observed over 50 cycles. Chemically stable SiO2 was coated on the surface of LiNi2/3Mn1/3O2 particles. A significant improvement in cyclability was attained with 3 wt% SiO2 coating, which is ascribable to the protection of LiNi2/3Mn1/3O2 particles from being dissolved into the electrolyte. 相似文献
18.
ZHAO HuiMin CHEN Yue QUAN Xie RUAN XiuLi 《科学通报(英文版)》2007,52(11):1456-1457
Zn-doped titanium oxide (TiO2) nanotubes electrode was prepared on a titanium plate by direct anodic oxidation and immersing method in sequence. Field emission scanning electron microscopy (FESEM) showed that the Zn-doped TiO2 nanotubes were well aligned and organized into high density uniform arrays with diameter ranging from 50 to 90 nm. The length and the thickness were about 200 and 15 nm respectively. TiO2 anatase phase was identified by X-ray diffraction (XRD). X-ray photoelectronspectroscopy (XPS) indicated that Zn ions were mainly located on the surface of TiO2 nanotubes in form of ZnO clusters. Compared with TiO2 nanotubes electrode, about 20 nm red shift in the spectrum of UV-vis absorption was observed. The degradation of pentachlorophenol (PCP) in aqueous solution under the same condition (initial concentration of PCP: 20 mg/L; concentration of Na2SO4:0.01 mol/L and pH: 7.03) was carried out using Zn-doped TiO2 nanotubes electrode and TiO2 nanotubes electrode. The degradation rates of PCP using Zn-doped TiO2 nanotubes electrode were found to be twice and 5.8 times as high as that using TiO2 nanotubes electrode by UV radiation (400 μw/cm^2) and visible light radiation (4500 μw/cm^2), respectively. 73.5% of PCP was removed using Zn-doped TiO2 nanotubes electrode against 45.5% removed using TiO2 nanotubes electrode in 120 min under UV radiation. While under visible light radiation, the degradation efficiency of PCP was 18.4% using Zn-doped TiO2 nanotubes electrode against 3.2% using TiO2 nanotubes electrode in 120 min. The optimum concentration of Zn doping was found to be 0.909%. The PCP degradation efficiencies of the 10 repeated experiments by Zn-doped TiO2 nanotubes electrode were rather stable with the deviation within 3.0%. 相似文献
19.
Guo-qiang Liu Xi Wang Ya-jie Gao Lei Wen Guang-yin Liu Jian-jie Zheng Peng Cen Ying Li 《矿物冶金与材料学报》2012,19(5):457-460
Spinel compounds LiNi0.5Mn1.3Ti0.2O4 (LNMTO) and Li4Ti5O12 (LTO) were synthesized by different methods. The particle sizes of LNMTO and LTO are 0.5–2 and 0.5–0.8 μm, respectively.
The LNMTO/LTO cell exhibits better electrochemical properties at both a low current rate of 0.2C and a high current rate of
1C. When the specific capacity was determined based on the mass of the LNMTO cathode, the LNMTO/LTO cell delivered 137 mA·h·g−1 at 0.2C and 118.2 mA·h·g−1 at 1C, and the corresponding capacity retentions after 30 cycles are 88.5% and 92.4%, respectively. 相似文献
20.
ZHANG Fangying ZHU Shenglong & TENG Yingyuan State Key Lab for Corrosion Protection Institute of Metal Research Chinese Academy of Sciences Shenyang China 《科学通报(英文版)》2004,49(16):1768-1771
Oxidationisaubiquitousphenomenonofnature.Theeconomiclossduetooxidationisverylargeeveryyear.Theinvestigationoftheadsorptionofoxygenonthesur-facesofmetalsisofgreatimportanceforbetterunder-standingoftheoxidationmechanismbecauseitistheverybeginningstageofoxidationofmetals.Itisgenerallybe-lievedthattheprocessofO2adsorptiononmetalsisinanorderofO2?O?O-?O2-,andthefollowingstagesareoxidenucleation,growthandtheoxidefilmformation.Astheprocessofadsorptionistooquicktobeobservedbyexperiments,atheoreticals… 相似文献