Shengkui Zhong

Soochow University (PRC), Wu-hsien, Jiangsu Sheng, China

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Publications (26)45.65 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: LiCoPO4-Li3V2(PO4)3 composite cathode material is synthesized by a chemical reduction and a lithiation method, with Co3V2O8 as the precursor and oxalic acid as the reductant. XRD result indicates that the composite is composed of olivine-type LiCoPO4 and monoclinic Li3V2(PO4)3. TEM, HRTEM and FFT results show that the LiCoPO4-Li3V2(PO4)3 particles are wrapped with nano-carbon webs, and the crystal particles contain the lattice fringes and diffraction spots of LiCoPO4 and Li3V2(PO4)3. The composite shows the stepped charge-discharge platforms which contain the potential plateaus of LiCoPO4 (~4.8 V) and Li3V2(PO4)3 (~3.6, 3.7, 4.1 and 4.5 V). During the potential range of 3.0-5.0 V, the composite delivers the specific capacities of 163.7, 133.6 and 93.8 mA h g−1 at 0.05, 0.5 and 2 C rates, respectively, and shows good cycling performance.
    Materials Letters 08/2015; 152:228-231. DOI:10.1016/j.matlet.2015.03.116 · 2.27 Impact Factor
  • Materials Letters 03/2015; 143. DOI:10.1016/j.matlet.2014.12.090 · 2.27 Impact Factor
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    ABSTRACT: The most severe bottleneck hindering the widespread application of fuel cell technologies is the difficulty in obtaining an inexpensive and abundant oxygen reduction reaction (ORR) catalyst. The concept of a heteroatom-doped carbon-based metal-free catalyst has recently attracted interest. In this study, a metal-free carbon nanoparticles-based catalyst hybridized with dual nitrogen and boron components was synthesized to catalyze the ORR in microbial fuel cells (MFCs). Multiple physical and chemical characterizations confirmed that the synthetic method enabled the incorporation of both nitrogen and boron dopants. The electrochemical measurements indicated that the co-existence of nitrogen and boron could enhance the ORR kinetics by reducing the overpotential and increasing the current density. The results from the kinetic studies indicated that the nitrogen and boron induced an oxygen adsorption mechanism and a four-electron-dominated reaction pathway for the as-prepared catalyst that was very similar to those induced by Pt/C. The MFC results showed that a maximum power density of ∼642 mW m−2 was obtained using the as-prepared catalyst, which is comparable to that obtained using expensive Pt catalyst. The prepared nitrogen- and boron-co-doped carbon nanoparticles might be an alternative cathode catalyst for MFC applications if large-scale applications and price are considered.
    Journal of Power Sources 12/2014; 272:344–350. DOI:10.1016/j.jpowsour.2014.08.114 · 5.21 Impact Factor
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    ABSTRACT: The xLiMn0.9Fe0.1PO4·yLi3V2(PO4)3/C (x:y=1:0, 9:1 5:1, 3:1, 1:1 and 0:1) cathode materials are synthesized by a ball–milling and post–calcination method. XRD results reveal that the xLiMn0.9Fe0.1PO4·yLi3V2(PO4)3/C (x,y≠0) composites are composed of LiMn0.9Fe0.1PO4 and Li3V2(PO4)3 phases, and no impurities are detected. In LiMn0.9Fe0.1PO4–Li3V2(PO4)3 system, most of the manganese, iron and vanadium elements in the raw materials tend to form the two major phases, and only small amounts of V, Mn and Fe as dopants enter into the lattice of LiMn0.9Fe0.1PO4 and Li3V2(PO4)3. Electrochemical tests show that the xLiMn0.9Fe0.1PO4·yLi3V2(PO4)3/C (x,y≠0) composites exhibit much better performance than the single LiMn0.9Fe0.1PO4/C. Among the samples, 5LiMn0.9Fe0.1PO4·Li3V2(PO4)3/C shows the best electrochemical performance. The sample delivers the specific capacities of 158.1, 140.7 and 100.2 mAh g−1 at 0.05, 1 and 4 C rates in the potential range of 2.5–4.5 V, and exhibits very long and flat discharge plateau around 4.0 V up to 1 C rate. The sample also shows good cycling performance at various C–rates.
    Electrochimica Acta 11/2014; 146:288–294. DOI:10.1016/j.electacta.2014.09.076 · 4.09 Impact Factor
  • Ling Wu, Shengkui Zhong, Jiajia Lu, Fan Lv, Jiequn Liu
    Materials Letters 01/2014; 115:60-63. DOI:10.1016/j.matlet.2013.10.040 · 2.27 Impact Factor
  • Ling Wu, Shengkui Zhong, Fan Lv, Jiequn Liu
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    ABSTRACT: LiMnPO4/C cathode material is prepared by a sol-gel combined ball milling and liquid nitrogen quenching method. XRD results reveal that quenching does not destroy the structure of LiMnPO4. The quenched sample, which is well crystallized with a single olivine type LiMnPO4 phase, shows a slightly contracted lattice parameters of a, b and c compared with the un-quenched sample. SEM and particle size analysis results reveal that quenching can inhibit the growth and agglomeration of LiMnPO4/C particles. TEM results show that quenching can result in the formation of a number of defects in LiMnPO4 crystals. Electrochemical tests indicate that liquid nitrogen quenching can greatly improve the electrochemical performances of LiMnPO4/C. The quenched sample shows the initial discharge capacities of 131.6, 125.8, 103.3 and 56.4 mAh g−1 at 0.05, 0.1, 0.5 and 1 C rates, respectively, which are much higher than those of un-quenched one.
    Materials Letters 11/2013; 110:38-41. DOI:10.1016/j.matlet.2013.07.112 · 2.27 Impact Factor
  • Ling Wu, Jiajia Lu, Shengkui Zhong
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    ABSTRACT: The xLiFePO4·yLi3V2(PO4)3/C cathode materials are synthesized by a sol spray drying method. X-ray diffraction results reveal that the xLiFePO4·yLi3V2(PO4)3/C (x,y ≠ 0) composites are composed of LiFePO4 and Li3V2(PO4)3 phases, and no impurities are detected. The samples show spherical particles with the size of 0.5–5 μm, and the tap densities of all the samples are higher than 1.5 g cm−3. Electrochemical tests show that the xLiFePO4·Li3V2(PO4)3/C (x,y ≠ 0) composites exhibit much better performance than the single LiFePO4/C or Li3V2(PO4)3/C. Among all the samples, 3LiFePO4·Li3V2(PO4)3/C possesses the best comprehensive performance in terms of the discharge capacity, average working voltage, and rate capability. At 1, 5, and 10 C rates, the sample shows first discharge capacities of 152.0, 134.3, and 116.8 mAh g−1 and capacity retentions of 99.2, 98.2, and 97.7 % after 100 cycles, respectively. The excellent electrochemical performance of micron-sized xLiFePO4·Li3V2(PO4)3/C (x,y ≠ 0) powders is owing to the homogeneous mixing of reactants at a molecular level by sol spray drying, the incorporation of fast ion conductor Li3V2(PO4)3, and the mutual doping in LiFePO4 and Li3V2(PO4)3.
    Journal of Solid State Electrochemistry 08/2013; 17(8). DOI:10.1007/s10008-013-2095-2 · 2.23 Impact Factor
  • Ling Wu, Shengkui Zhong, Jiajia Lu, Jiequn Liu, Fan Lv
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    ABSTRACT: LiMn1-x Crx PO4/C (x = 0, 0.01, 0.03, and 0.05) compounds are synthesized by a sol–gel combined ball milling method. The effects of Cr doping on the structure, morphology, and electrochemical performance of LiMnPO4 are investigated. XRD analysis results indicate that all the samples exhibit the single LiMnPO4 phase and Cr ions substitute on Mn site (x ≤ 0.03), with charge compensating vacancies on Li site. The vacancies are of benefit to improving the electronic conductivity of LiMnPO4. SEM studies reveal that Cr doping can effectively inhibit the aggregation of LiMnPO4 particles. Electrochemical tests show that the Cr-doped samples exhibit higher initial capacities and better cycling performance than the undoped one. LiMn0.97Cr0.03PO4/C exhibit the best electrochemical performance that the first specific discharge capacity is 132.4 mAh g−1 at 0.1 C rate, and the capacity retention is 94.8 % after 30 cycles.
    Ionics 07/2013; 19(7). DOI:10.1007/s11581-013-0919-9 · 1.84 Impact Factor
  • Integrated Ferroelectrics 01/2013; 141(1):195-195. DOI:10.1080/10584587.2012.733614 · 0.37 Impact Factor
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    ABSTRACT: LiMnPO4/C composites were synthesized via solid-state reaction with different carbon sources: sucrose, citric acid and oxalic acid. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical performance test. The results of XRD reveal that carbon coating has no effect on the phase of LiMnPO4. The LiMnPO4/C synthesized at 600 °C with citric acid as carbon source shows an initial discharge capacity of 117.8 mAh·g−1 at 0.05 C rate. After 30 cycles, the capacity remains 98.2 mAh·g−1. The improved electrochemical properties of LiMnPO4/C is attributed to the decomposition of organic acid during the sintering process.
    Rare Metals 10/2012; 31(5). DOI:10.1007/s12598-012-0542-3 · 0.81 Impact Factor
  • Shengkui Zhong, Ling Wu, Jiequn Liu
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    ABSTRACT: 9LiFePO4·Li3V2(PO4)3/C composite cathode material is prepared by a sol–gel method, using ferric citrate, V2O5, Li2CO3, NH4H2PO4 and citric acid as raw materials. The composite material is composed of the olivine LiFePO4 and monoclinic Li3V2(PO4)3 phases. XRD results indicate that most of the iron and vanadium in the raw materials tend to form the LiFePO4 and Li3V2(PO4)3 phases, and only small amounts of Fe and V as the dopants enter into the lattice of Li3V2(PO4)3 and LiFePO4, respectively. The electronic conductivity and Li+ diffusion coefficient of 9LiFePO4·Li3V2(PO4)3/C are 6.615 × 10−3 S cm−1 and ∼10−10 cm2 s−1, which are three orders of magnitude and one order of magnitude larger than those of the LiFePO4/C, respectively. The composite material shows a first discharge specific capacity of 131.3 mAh g−1 and capacity retention of 95.1% after 200 cycles at 10 C rate. Compared with the LiFePO4/C, its rate capability and cycle performance are both remarkably improved.
    Electrochimica Acta 07/2012; 74:8–15. DOI:10.1016/j.electacta.2012.03.181 · 4.09 Impact Factor
  • Shengkui Zhong, Wei Chen, Ling Wu, Jiequn Liu
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    ABSTRACT: 5LiFePO4⋅Li3V2(PO4)3/C composite cathode material is synthesized by a polyethylene glycol (PEG)-assisted rheological phase method. As a surfactant and dispersing agent, PEG can effectively inhabit the aggregation of colloidal particles during the formation of the gel. Meanwhile, PEG will coat on the particles to play the role of carbon source during the sintering. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy, and electrochemical methods. XRD results indicate that the 5LiFePO4⋅Li3V2(PO4)3/C composites are well crystallized and contain olivine-type LiFePO4 and monoclinic Li3V2(PO4)3 phases. The composite synthesized at 650 °C exhibits the initial discharge capacities of 134.8 and 129.9 mAh g−1 and the capacity retentions of 96.2 and 97.1 % after 50 cycles at 1C and 2C rates, respectively.
    Ionics 05/2012; 18(5). DOI:10.1007/s11581-012-0701-4 · 1.84 Impact Factor
  • Shengkui Zhong, Ling Wu, Junchao Zheng, Jiequn Liu
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    ABSTRACT: The 9LiFePO4·Li3V2(PO4)3/C composite cathode material is synthesized by spray-drying and post-calcining method based on citrate. The composite is well crystallized, and contains olivine-type LiFePO4 and monoclinic Li3V2(PO4)3 phases. The composite material exhibits spherical particles in the size of 0.5–5 μm, and shows a high tap-density of 1.64 g cm− 3. The electrochemical performance of the material is excellent. At 5C and 10C rates, the sample exhibits the initial discharge capacities of 135.3 and 109.6 mAh g− 1 and capacity retentions of 96.2% and 93.7% after 100 cycles, respectively. The homogenous mixing of the LiFePO4 and fast ion conductor additive Li3V2(PO4)3, which is resulted from spray-drying, can be the reason why the composite has good rate capability.
    Powder Technology 03/2012; 219:45–48. DOI:10.1016/j.powtec.2011.12.005 · 2.27 Impact Factor
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    ABSTRACT: The effect of molecular orientation on the electron transport behavior of single porphyrin sandwiched between two gold (111) electrodes is investigated by density functional theory calculations combined with non-equilibrium Green’s function method. The results show that the porphyrin with parallel connection to gold (111) electrodes is more conductive than the porphyrin with diagonal connection to gold (111) electrodes. The mechanism of the difference of electron transport for these two molecular junctions is analyzed from the transmission spectra and the molecular projected self-consistent Hamiltonian states. It is found that the intrinsic nature of the molecule, such as the π-conjugated framework and the strength of molecule–electrode coupling, are the essential reason for generating this difference of electron transport for the two molecular systems.
    Current Applied Physics 11/2011; 11(6):1349-1353. DOI:10.1016/j.cap.2011.04.001 · 2.03 Impact Factor
  • Shengkui ZHONG, You WANG, Jiequn LIU, Kang WAN, Fan LÜ
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    ABSTRACT: The layered material of Ce-doped LiNi1/3Mn1/3Co1/3O2 with α-NaFeO2 was synthesized by a co-precipitation method. X-ray diffraction (XRD) showed that Ce-doped LiNi1/3Mn1/3Co1/3O2 had the same layered structure as the undoped LiNi1/3Mn1/3Co1/3O2. The scanning electron microscopy (SEM) images exhibited that the particle size of Ce-doped LiNi1/3Mn1/3Co1/3O2 was smaller than that of the undoped LiNi1/3Mn1/3Co1/3O2. The Ce-doped LiNi1/3Mn1/3Co1/3O2 samples were investigated on the Li extraction/insertion performances through charge/discharge, cyclic voltammogram (CV), and electrochemical impedance spectra (EIS). The optimal doping content of Ce was x=0.02 in the LiNi1/3–xMn1/3Co1/3CexO2 samples to achieve high discharge capacity and good cyclic stability. The electrode reaction reversibility was enhanced, and the charge transfer resistance was decreased through Ce-doping. The improved electrochemical performances of the Ce-doped LiNi1/3Mn1/3Co1/3O2 cathode materials were attributed to the addition of Ce4+ ion by stabilizing the layer structure.
    Journal of Rare Earths 09/2011; 29(9):891-895. DOI:10.1016/S1002-0721(10)60562-5 · 1.34 Impact Factor
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    ABSTRACT: The layered Li(Ni1/3Co1/3Mn1/3)1-xYxO2 cathode materials (x = 0, 0.03, 0.06, 0.09) were prepared by a co-precipitation method. The properties of the Y-doped LiNi1/3Mn1/3Co1/3O2 were investigated by X-ray diffraction (XRD), scanning electron microscopic (SEM), and electrochemical measurements. XRD studies show that the Y-doped LiNi1/3Mn1/3Co1/3O2 has the same layered structure as the undoped LiNi1/3Mn1/3Co1/3O2. SEM images exhibit that the particle size of Y-doped LiNi1/3Mn1/3Co1/3O2 is smaller than that of the undoped LiNi1/3Mn1/3Co1/3O2 and the smallest particle size is only about 2μm. The Y-doped LiNi1/3Mn1/3Co1/3O2 samples were investigated on the Li extraction/insertion performances through charge/discharge, cyclic voltammogram (CV), and electrochemical impedance spectra (EIS). The optimal doping content of Y is that x = 0.06 in the Li(Ni1/3Co1/3Mn1/3)1-xYxO2 samples to achieve high discharge capacity and good cyclic stability. The electrode reaction reversibility was enhanced, and the charge transfer resistance was decreased through Y-doping. The improved electrochemical performances of the Y-doped LiNi1/3Mn1/3Co1/3O2 cathode materials are attributed to the addition of Y ion by stabilizing the layer structure.
    Integrated Ferroelectrics 01/2011; 127(1):150-156. DOI:10.1080/10584587.2011.575736 · 0.37 Impact Factor
  • Minggui Xiao, Gangchen Sun, Shengkui Zhong
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    ABSTRACT: In this paper, an experimental method of chemical flocculation was proposed for the problems of waste flush fluid in Guangxi Pingguo Aluminum Company. The Effect of the value of pH, the type of flocculants, the proper amount of flocculants, the adding sequencing, and stirring speed on the sedimentation properties of the mud was investigated, individually. The results indicate that the optimum sedimentation conditions of the mud were obtained as follows: the pH is 7.0, the flocculant is inorganic PPAC mixed with organic polymer PAM, the dosage is 20g/t, the adding sequencing is first PAM and then PPAC, the stirring speed is 90r/min.
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    ABSTRACT: The electron transport behaviors of oxygen and carbon monoxide complexes of Fe-porphyrin (FeP) are investigated by nonequilibrium Green's function techniques combined with Density Functional Theory calculations. The results show that the molecular current of FeP decreases dramatically after adsorptions of oxygen and carbon monoxide. The molecular current decreases with a order of FeP > FeP+O2 complex > FeP+CO complex. This change of the molecular current after adsorption of oxygen or carbon monoxide can be potentially used to design a molecular sensor or a molecular switch.
    Integrated Ferroelectrics 01/2011; 127(1):91-96. DOI:10.1080/10584587.2011.575672 · 0.37 Impact Factor
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    ABSTRACT: Li3V2(PO4)3/C samples were synthesized by two different synthesis methods. Their influence on electrochemical performances of Li3V2(PO4)3/C as cathode materials for lithium-ion batteries was investigated. The structure and morphology of Li3V2(PO4)3/C samples were characterized by X-ray diffraction and scanning electron microscopy. Electrochemical performance was characterized by charge/discharge, cyclic voltammetry, and alternating current (AC) impedance measurements. Li3V2(PO4)3/C with smaller grain size showed better performances in terms of the discharge capacity and cycle stability. The improved electrochemical properties of the Li3V2(PO4)3/C were attributed to the decreasing grain size and enhanced electrical conductivity produced via low temperature route. AC impedance measurements also showed that the Li3V2(PO4)3/C synthesized by low temperature route significantly decreased the charge-transfer resistance and shortened the migration distance of lithium ion.
    Ionics 03/2010; 16(2):117-121. DOI:10.1007/s11581-009-0362-0 · 1.84 Impact Factor
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    ABSTRACT: The effect of fluorine substitution on the electrochemical properties of Li3V 2(PO4)3 cathode materials was studied. Samples with stoichiometric proportions of Li3V 2(PO4)3−xFx (x=0,0.05,0.10,0.15) were prepared by adding LiF in the starting materials of Li3V 2(PO4)3. XRD studies showed that the F-substituted Li3V 2(PO4)3 had the same monoclinic structure as the un-substituted Li3V 2(PO4)3. SEM images showed that F-substitution Li3V 2(PO4)3 had a regular and uniform particles. The results of electrochemical measurement showed that F-substitution can improve the rate capability of these cathode materials. The Li3V 2(PO4)2.90F0.10 sample showed the best high rate performance. Its discharge capacity at 10 C rate was 117 mA h g−1 with 30th capacity retention of about 90.60%. The electrode reaction reversibility and electronic conductivity was enhanced, and the charge transfer resistance was decreased through F-substitution. The improved electrochemical performance of F-substitution Li3V 2(PO4)3 cathode materials were attributed to the above factors.
    Solid State Communications 10/2009; 149(39):1679-1683. DOI:10.1016/j.ssc.2009.06.019 · 1.70 Impact Factor