Browsing by Author "Liu, HK"

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    Enhanced reversible lithium storage in a nanosize silicon/graphene composite.
    (Elsevier, 2010-02) Chou, SL; Wang, JZ; Choucair, M; Liu, HK; Stride, JA; Dou, SX
    Si/graphene composite was prepared by simply mixing of commercially available nanosize Si and graphene. Electrochemical tests show that the Si/graphene composite maintains a capacity of 1168 mAh g−1 and an average coulombic efficiency of 93% up to 30 cycles. EIS indicates that the Si/graphene composite electrode has less than 50% of the charge-transfer resistance compared with nanosize Si electrode, evidencing the enhanced ionic conductivity of Si/graphene composite. The enhanced cycling stability is attributed to the fact that the Si/graphene composite can accommodate large volume charge of Si and maintain good electronic contact. © 2010, Elsevier Ltd.
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    Irradiation Si on carbon nanotube paper as a flexible anode material for lithium-ion batteries
    (American Scientific Publishers, 2012-02-01) Chou, SL; Ionescu, M; Wang, JZ; Winton, BR; Liu, HK
    Silicon/single-walled carbon nanotube (SWCNT) composite paper was modified by low energy ion implantation using Si to obtain a flexible composite paper. Raman and FE-SEM results show that structure of SWCNT could be destroyed by the implantation. Electrochemical measurements display that the implanted Si can improve the specific capacity and the reversible capacity of CNT paper. After 50 cycles, the specific capacity of Si-implanted CNT paper is 30% higher than the pristine CNT. © 2020 Ingenta
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    Lithium rich and deficient effects in LixCoPO4 (x=0.90, 0.95, 1, 1.05) as cathode material for lithium-ion batteries
    (Elsevier, 2013-01-15) Xu, J; Chou, SL; Avdeev, M; Sale, M; Liu, HK; Dou, SX
    A series of LixCoPO4 (x = 0.90, 0.95, 1, 1.05) compounds with different lithium content in the starting compositions were prepared by the sol–gel method. The phase identification was carried out by X-ray diffraction and neutron diffraction. The structure, atom positions, and occupancies were characterized by neutron diffraction. The morphology of LixCoPO4 (x = 0.90, 0.95, 1, 1.05) was examined by field emission scanning electron microscopy. Electrochemical analysis indicated that Li0.95CoPO4 presented the highest discharge capacity at various current densities among all the different x value compounds. The Li0.95CoPO4 showed better cycling stability and coulombic efficiency in the room temperature ionic liquid electrolyte ([C3mpyr][NTf2] containing 1 M LiNTf2) at various current densities in the voltage range of 3.5–5.0 V than in the conventional electrolyte (1 M LiPF6 in ethylene carbonate:diethyl carbonate).© 2012, Elsevier Ltd.
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    Study of oxygen incorporation in PLD MgB2 films by Rutherford backscattering spectroscopy
    (Institute of Electrical and Electronics Engineers (IEEE), 2007-06) Zhao, Y; Ionescu, M; Dou, SX; Liu, HK
    The Rutherford backscattering (RBS) method has been employed to study the incorporation of oxygen into MgB2 films during their fabrication by pulsed-laser deposition (PLD). A series of MgB2 thin film samples were analyzed, including two films produced in situ on Al2O3 - c substrates (with higher T-c and lower T-c) with an on-axis geometry, one film produced in situ with an off-axis geometry, and one film produced ex situ, with a bulk-like T-c. The amount of oxygen detected by RBS, which is stable in the form of MgO, appears to be correlated with the T-c of the films, the higher the T-c the lower the oxygen content. The superconducting properties of the thin films are discussed in the context of the RBS results. © 2007, Institute of Electrical and Electronics Engineers (IEEE)
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    TiO2(B)@anatase hybrid nanowires with highly reversible electrochemical performance
    (Elsevier, 2011-01-01) Zang, ZX; Du, GD; Guo, ZP; Yu, XB; Chen, ZX; Guo, TL; Sharma, N; Liu, HK
    Novel TiO2(B)@anatase hybrid nanowires with a bicrystalline structure consisting of TiO2(B) core and anatase shell exhibit superior Li ion storage capacities, cycling stability and rate capability. Owing to the excellent electrochemical performance, TiO2(B)@anatase hybrid nanowires could be promising anode materials for lithium ion batteries. Crown Copyright (C) 2010 Published by Elsevier B.V.