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ABSTRACT: Liquid electrolyte plays a key role in commercial lithium-ion batteries to allow conduction of lithium-ion between cathode and anode. Traditionally, taking into account the ionic conductivity, viscosity and dissolubility of lithium salt, the salt concentration in liquid electrolytes is typically less than 1.2 mol l(-1). Here we show a new class of 'Solvent-in-Salt' electrolyte with ultrahigh salt concentration and high lithium-ion transference number (0.73), in which salt holds a dominant position in the lithium-ion transport system. It remarkably enhances cyclic and safety performance of next-generation high-energy rechargeable lithium batteries via an effective suppression of lithium dendrite growth and shape change in the metallic lithium anode. Moreover, when used in lithium-sulphur battery, the advantage of this electrolyte is further demonstrated that lithium polysulphide dissolution is inhibited, thus overcoming one of today's most challenging technological hurdles, the 'polysulphide shuttle phenomenon'. Consequently, a coulombic efficiency nearing 100% and long cycling stability are achieved.
Nature Communications 02/2013; 4:1481. · 7.40 Impact Factor
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ABSTRACT: A novel in situ time-resolved synchrotron X-ray absorption spectroscopy (XAS) was introduced for the dynamic studies during fast chemical and electrochemical delithiation of LiFePO(4). The lithium diffusion in LiFePO(4) and the reaction mechanisms for both processes were investigated. This approach opens new opportunities for dynamic studies of various energy storage systems.
Chemical Communications 10/2012; · 6.17 Impact Factor
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ABSTRACT: A chitinase gene (RCH8) in plasmid vector pCAMBIA1308 was delivered into 3 wheat cultivars (Yangmai 158, Wan 9210, Wanmai 32) by low energy Ar+ beam-mediated method. Preliminary calli from treated mature embryos were first selected on hygromycin (Hm, 20 or 30 mg/L)
containing medium. After the resistant calli formed, they were transferred to the regeneration medium with 10 or 20 mg/L Hm.
All the three wheat varieties obtained transgenic plants. PCR and PCR-Southern assays showed that most plants regenerated
from the resistant calli were positive transgenic plants. Southern blot of the positive green plants confirmed stable integration
of alien DNA into wheat genome. The plant transformation frequencies varied with the variety and ion dose implanted. Wanmai
32 possessed the highest transformation frequency, reaching 3.8% at a suitable implantation dose. The transformation frequency
of Yangmai 158 and Wan 9210 varied from 0.5% to 2.5% and from 0.5% to 1.4%, respectively. Progeny test for resistance to wheat
scab showed that the leaf extract of R1 generation inhibited the growth of wheat scab strain F0 and F15.
Keywordsion beam-wheat mature embryos-chitinase gene-transgenic plants-scab resistance
Chinese Science Bulletin 04/2012; 46(4):318-322. · 1.32 Impact Factor
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ABSTRACT: Transition metal atom M (M = Cu, Ag, Au) adsorption on CeO(2)(110), a technologically important catalytic support surface, is investigated with density-functional theory within the DFT+U formalism. A set of model configurations was generated by placing M at three surface sites, viz., on top of an O, an O bridge site, and a Ce bridge site. Prior to DFT optimization, small distortions in selected Ce-O distances were imposed to explore the energetics associated with reduction of Ce(4+) to Ce(3+) due to charge transfer to Ce during M adsorption. Charge redistribution is confirmed with spin density isosurfaces and site projected density of states. We demonstrate that Cu and Au atoms can be oxidized to Cu(2+) and Au(2+), although the adsorption energy, E(ads), of Au(2+) is less favorable and, unlike Cu(2+), it has not been experimentally observed. Oxidation of Ag always results in Ag(+). For M adsorption at an O bridge site, E(ads)(2NN) > E(ads)(3NN) > E(ads)(1NN) where NN denotes the nearest neighbor Ce(3+) site relative to M. Alternatively, for M adsorption at a Ce bridge site, E(ads)(3NN) > E(ads)(2NN) > E(ads)(1NN). The adsorption behavior of M on CeO(2) (110) is compared with M adsorption on CeO(2)(111).
Physical Chemistry Chemical Physics 02/2012; 14(6):1923-33. · 3.57 Impact Factor
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Journal of Power Sources 01/2012; 218. · 4.95 Impact Factor
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ABSTRACT: A uniform and thin amorphous layer of a C-N compound was coated on porous Li(4)Ti(5)O(12) by pyrolysis of urea on its surface at a rather low temperature of 400 °C in an Ar atmosphere. Such a C-N coating layer greatly improved the electrochemical performance of Li(4)Ti(5)O(12). After coating, Li(4)Ti(5)O(12) showed good rate and excellent cycling performance. Reversible capacities for the coated sample of 134 and 105 mAh g(-1) were obtained at current rates of 5C and 10C, respectively, in the voltage range of 1-2.2 V, which is approximately two and five times higher than those of pristine Li(4)Ti(5)O(12) at the same current rates. Excellent capacity retention of 95.8 % was achieved for the coated sample after 2000 cycles in a half cell at a 2C rate.
ChemSusChem 12/2011; 5(3):526-9. · 6.83 Impact Factor
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Advanced Materials 09/2011; 23(42):4938-41. · 13.88 Impact Factor
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ABSTRACT: We report a new synchrotron based in situ X-ray diffraction (XRD) technique to study the chemical delithiation of LiFePO(4). This technique provides a new powerful tool to study chemical reactions with excellent time-resolving power for dynamic studies.
Chemical Communications 07/2011; 47(25):7170-2. · 6.17 Impact Factor
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Advanced Materials 03/2011; 23(11):1385-8. · 13.88 Impact Factor
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ABSTRACT: Cu, Mn and Ag nanoparticles are loaded on nanostructured mesoporous CeO2 as catalysts for CO oxidation. The Cu/CeO2 catalyst exhibits an obvious deactivation after the stability test at 95 degrees C for 60 h. This is caused by carbon deposition as confirmed by FTIR spectroscopy, Raman spectroscopy and thermogravimetry-differential scanning calorimetry-mass spectroscopy (TG-DSC-MS) analysis. It is found that the Cu-Mn or Cu-Ag binary metal catalysts supported on the nanostructured CeO2 exhibit much improved activity and stability in CO oxidation. In ease case, carbon deposition is absent in the similar stability test, due to enhanced oxygen adsorption property.
Journal of Nanoscience and Nanotechnology 03/2011; 11(3):1923-8. · 1.56 Impact Factor
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ABSTRACT: The effects of M (M=Mn,Pr,Sn,Zr) doping on the redox thermodynamics of CeO2 have been investigated using first-principles density-functional theory calculations with the on-site Coulomb interaction taken into account. Two different mechanisms for the O-vacancy formation in doped CeO2 have been clarified. Compared with the case of pure CeO2, the decrease in the O-vacancy formation energy for the Zr-doped CeO2 is mostly caused by the structural distortion, whereas the decrease for Mn-, Pr-, or Sn-doped CeO2 originates from the electronic modification as well as from the structural distortion. It is found that the electronic modification occurs in those dopants whose uttermost atomic orbitals are half or fully occupied by the filling of the excess electrons left by the formation of the O vacancy. Two effects also contribute to concentration dependence of the O-vacancy formation energies for different dopant species.
Phys. Rev. B. 09/2010; 82(12).
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Advanced Functional Materials 08/2010; 20(19):3358 - 3365. · 10.18 Impact Factor
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ABSTRACT: The thermal decomposable species in the solid electrolyte interphase (SEI) film on Cr2O3 powder anode at different lithiated and delithiated states in the first cycle were analyzed by thermogravimetry and mass
spectrometry (TG-MS) technique. The weight loss ratio in a fully lithiated Cr2O3 electrode during TG measurement at 50–500°C is 8.9wt%, which is decreased to 1.5wt% for a fully delithiated Cr2O3 electrode. This indicates that the SEI film on Cr2O3 powder anode is decomposed electrochemically upon delithiation. The main gas products are CH2=CH2, CO2, and CH3-containing volatile species in thermal reaction. They are released step-by-step in four characteristic temperature regions,
which were originated mainly from oligomer and polyethylene-oxide-like species, partly from ROCO2Li. It is also observed that the amount of thermal decomposable components in the SEI film on the fully lithiated Cr2O3 powder electrode is much higher than that on graphite and hard carbon anodes, indicating different SEI features of transition
metal oxide anodes.
Ionics 01/2009; 15(1):91-96. · 1.29 Impact Factor
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ABSTRACT: We fabricated ZnO photoelectrodes at room temperature by doctor-blading ZnO gel; the adequate interparticle connection and the effective ammonia activation process improved the flexible DSC's efficiency to 3.8% (under 100 mW cm(-2)).
Chemical Communications 08/2007; · 6.17 Impact Factor
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ABSTRACT: Well-dispersed spherical lanthanum oxycarbonate (La2O2CO3) and La2O3 particles with a flower-like morphology were synthesized via a simultaneous polymerization–precipitate reaction, metamorphic reconstruction, and mineralization under a hydrothermal condition as well as subsequent calcination. The La2O2CO3 and La2O3 microspheres obtained consist of about 20 or 40 nm thick nanosheets as petals, respectively. They have an open three-dimensional mesoporous and hollow structure and possess a high surface area, large pore volume, and marked thermal stability. These novel porous structural lanthanum-based materials could be used as catalyst supports for many reactions.
Journal of the American Ceramic Society 06/2007; 90(8):2576 - 2581. · 2.27 Impact Factor
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ABSTRACT: Cheap and environmentally benign electrochemical energy conversion and storage devices, including a dye-sensitized solar cell (DSSC) using an AlI3-ethanol electrolyte and a new Al/I2 primary battery, are reported. The AlI3-ethanol electrolyte can be prepared simply by adding aluminum powder and iodine into ethanol at ambient conditions. The DSSC using this AlI3-ethanol electrolyte achieved an energy conversion efficiency of 5.9% at AM 1.5 (100 mW/cm-2). In the Al/I2 battery, AlI3 is formed spontaneously when aluminum and iodine electrodes are brought into contact at room temperature. Then I- anions transport across the AlI3 solid electrolyte for further electrochemical reactions.
Journal of the American Chemical Society 08/2006; 128(27):8720-1. · 9.91 Impact Factor
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ABSTRACT: Nearly monodisperse flowerlike CeO2 microspheres were synthesized via a simultaneous polymerization-precipitate reaction, metamorphic reconstruction, and mineralization under hydrothermal condition as well as subsequent calcination. The obtained CeO2 microsphere consists of 20-30 nm thick nanosheets as petals. It has an open three-dimensional (3D) porous and hollow structure and possesses high surface area, large pore volume, and marked hydrothermal stability. It can be doped easily after synthesis, and the initial 3D texture is maintained. The controlling factors and a possible formation mechanism are discussed in detail. This novel material can be used as a support for catalysts with various purposes. With CuO loaded on flowerlike CeO2, the catalytic activities and hydrothermal stability of Cu/CeO2 for ethanol stream reforming were examined. At 300 degrees C, the H2 selectivity reached a maximum value of 74.9 mol %, while CO was not detected within the precision of the gas chromatogram. It produced a hydrogen-rich gas mixture in the wide temperature range (300-500 degrees C) and showed excellent hydrothermal stability at high temperature (550 degrees C), which is a good choice for ethanol processors for hydrogen fuel cell applications.
The Journal of Physical Chemistry B 08/2006; 110(27):13445-52. · 3.70 Impact Factor
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ABSTRACT: Metallic lithium reacts with biphenyl in 1,2-dimethoxyethane (DME) solvent at room temperature. This reaction has been studied using density functional theory (DFT) at the B3LYP level together with the 6-311++G (d,p) basis set. From the energy results of the corresponding optimized geometries for intermediate complexes, the reaction can be interpreted as a charge-transfer process between lithium and biphenyl followed by Li+ coordination with ether oxygens in DME. In addition, the experimentally observed vibrational bands can be unambiguously assigned and interpreted according to the normal modes calculated for the biphenyl-Li-DME complex. This organic complex solution has been demonstrated as a very effective chemical lithiation agent. V2O5 can be lithiated up to 1.45 lithium ions per formula. The lithiated V2O5 shows a high Li-extraction capacity of 173 mAh/g as cathode material for lithium ion batteries.
The Journal of Physical Chemistry B 07/2006; 110(21):10341-7. · 3.70 Impact Factor
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ABSTRACT: Here we report a spontaneous combustion reaction in synthesizing Pt hollow capsules. In brief, Pt nanoparticles were loaded on the surface of colloidal carbon spheres by wet-chemical impregnation. When Pt-loaded carbon spheres were taken out of an argon-filled tube furnace at room temperature and exposed to air, they underwent spontaneous combustion. The internal carbon spheres templates were removed to leave nanostructured Pt hollow capsules. There are at least two critical conditions for the occurrence of the spontaneous combustion: the Pt particle size is below 5.8 nm, and the hydrogen content in the carbon spheres is above 2.570 wt %. Such a reaction is interesting for the preparation of metal hollow spheres and is also relevant with respect to removal of accumulated carbon on catalysts and for soot oxidation at room temperature.
Chemistry 06/2006; 12(15):4083-90. · 5.93 Impact Factor
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ABSTRACT: It was observed that the ionic conductivity of the solid-state electrolyte LiI/3-hydroxypropionitrile (HPN) = 1:4 (molar ratio) decreased dramatically with increasing iodine (I(2)) concentration, which differs from the conduction behavior of the Grotthuss transport mechanism observed in liquid or gel electrolytes. The short-circuit photocurrent density (J(sc)) of the dye-sensitized solar cell (DSSC) based on this electrolyte system increases with increasing I(2) concentration until LiI/I(2) is 1:0.05 (molar ratio). Beyond this limitation, the J(sc) decreases. At low I(2) concentrations (I(2)/LiI < or = 0.05), the J(sc) is mainly affected by the diffusion of I(3)(-). An increase of the I(2) concentration leads to the enhancement of the diffusion of I(3)(-) and an increase of the J(sc). At high I(2) concentrations (I(2)/LiI > 0.05), the factors, including the increased light absorption by the I(3)(-), the increased recombination of electrons at the photoanode with I(3)(-), and the reduced ionic conductivity of the electrolyte, lead to a decrease of J(sc). At the same time, the open-circuit voltage (V(oc)) of the DSSC decreases monotonically with the ratio of I(2)/LiI due to increased dark current in the DSSC. The increased absorption of visible light by the electrolyte, the enhanced dark current, and the reduced ionic conductivity of the electrolyte contribute to the performance variation of the corresponding solid-state DSSC with increasing I(2) concentration.
The Journal of Physical Chemistry B 03/2006; 110(12):5970-4. · 3.70 Impact Factor
