Publications (30) View all
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Article: Scalable Functionalized Graphene Nano-platelets as Tunable Cathodes for High-performance Lithium Rechargeable Batteries.
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ABSTRACT: High-performance and cost-effective rechargeable batteries are key to the success of electric vehicles and large-scale energy storage systems. Extensive research has focused on the development of (i) new high-energy electrodes that can store more lithium or (ii) high-power nano-structured electrodes hybridized with carbonaceous materials. However, the current status of lithium batteries based on redox reactions of heavy transition metals still remains far below the demands required for the proposed applications. Herein, we present a novel approach using tunable functional groups on graphene nano-platelets as redox centers. The electrode can deliver high capacity of ~250 mAh g(-1), power of ~20 kW kg(-1) in an acceptable cathode voltage range, and provide excellent cyclability up to thousands of repeated charge/discharge cycles. The simple, mass-scalable synthetic route for the functionalized graphene nano-platelets proposed in this work suggests that the graphene cathode can be a promising new class of electrode.Scientific Reports 03/2013; 3:1506. -
Dataset: srep00704-supplementary
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Article: A combined first principles and experimental study on Na 3 V 2 (PO 4 ) 2 F 3 for rechargeable Na batteries
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ABSTRACT: The electrochemical properties of Na 3 V 2 (PO 4) 2 F 3 in a Na rechargeable battery were investigated through a combined computational and experimental study. Ex situ XRD results indicate that the reversible sodiation/desodiation occurs via one phase reaction and the structure of Na 3Àx V 2 (PO 4) 2 F 3 remains quite stable upon extraction and insertion of sodium. Notable is that the one phase reaction is accompanied by the negligible variation in lattice parameters ($1%) and unit cell volume ($2%) which results in a good cycle performance. It is further noticed that the desodiated phase is thermally stable up to 550 C implying the excellent safety characteristic of the charged electrode. The first principles calculations elucidate the mechanisms of the structural evolution and the electrochemical behavior of Na 3Àx V 2 (PO 4) 2 F 3 upon battery cycling.Materials Chemistry 08/2012; -
Article: New iron-based mixed-polyanion cathodes for lithium and sodium rechargeable batteries: combined first principles calculations and experimental study.
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ABSTRACT: New iron-based mixed-polyanion compounds Li(x)Na(4-x)Fe(3)(PO(4))(2)(P(2)O(7)) (x = 0-3) were synthesized, and their crystal structures were determined. The new compounds contained three-dimensional (3D)sodium/lithium paths supported by P(2)O(7) pillars in the crystal. First principles calculations identified the complex 3D paths with their activation barriers and revealed them as fast ionic conductors. The reversible electrode operation was found in both Li and Na cells with capacities of one-electron reaction per Fe atom, 140 and 129 mAh g(-1), respectively. The redox potential of each phase was ∼3.4 V (vs Li) for the Li-ion cell and ∼3.2 V (vs Na) for the Na-ion cell. The properties of high power, small volume change, and high thermal stability were also recognized, presenting this new compound as a potential competitor to other iron-based electrodes such as Li(2)FeP(2)O(7), Li(2)FePO(4)F, and LiFePO(4).Journal of the American Chemical Society 06/2012; 134(25):10369-72. · 9.91 Impact Factor -
Article: Electrochemical performance and ex situ analysis of ZnMn2O4 nanowires as anode materials for lithium rechargeable batteries
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ABSTRACT: One-dimensional ZnMn2O4 nanowires have been prepared and investigated as anode materials in Li rechargeable batteries. The highly crystalline ZnMn2O4 nanowires about 15 nm in width and 500 nm in length showed a high specific capacity of about 650 mAh·g−1 at a current rate of 100 mA·g−1 after 40 cycles. They also exhibited high power capability at elevated current rates, i.e., 450 and 350 mAh·g−1 at current rates of 500 and 1000 mA·g−1, respectively. Formation of Mn3O4 and ZnO phases was identified by ex situ X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies after the initial discharge-charge cycle, which indicates that the ZnMn2O4 phase was converted to a nanocomposite of Mn3O4 and ZnO phases immediately after the electrochemical conversion reaction. KeywordsEnergy storage–lithium rechargeable battery–anode–ZnMn2O4 –nanowireNano Research 04/2012; 4(5):505-510. · 6.97 Impact Factor
