Alok Kumar Rai

High rate performance of a Na3V2(PO4)3/C cathode prepared by pyro-synthesis for sodium-ion batteries

A Na3V2(PO4)3/C cathode synthesized by a polyol-assisted pyro-synthetic reaction and subsequent sintering delivered a discharge capacity of 235 mA h g−1, corresponding to an extraction of 4 Na per formula with steady capacity retention and impressive rate capabilities that maintain 56% of theoretical capacity at 2.67 C.

Enhanced electrochemical performance of novel K-doped Co3O4 as the anode material for secondary lithium-ion batteries

K-doped Co3O4 was prepared by a solvothermal method in polyol medium, followed by annealing at a low temperature of 400 °C for 5 h. The obtained samples were characterized by the synchrotron X-ray diffraction pattern, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, field-emission transmission electron microscopy and high-resolution transmission electron microscopy. Synchrotron XRD analysis demonstrates that the K+ ion doping caused no change in the phase structure, and a highly crystalline KxCo3−xO4−δ (x = 0.08) powder without any impurity was obtained. When applied as the anode material, the K+-doped Co3O4 electrode exhibits a much better rate capability and cycling stability, and could retain a charge capacity of 351.3 mA h g−1 at 3 C, while undoped Co3O4 exhibits only 144.3 mA h g−1 at the same rate. In addition, the electrochemical impedance spectroscopy also reveals that the K+-doped Co3O4 electrode has the highest electronic conductivity compared to an undoped sample. However, the improvement in the doped sample is due to the influence of K+ ions on the increased electronic conductivity, diffusion efficiency, and kinetic properties of Co3O4 during the lithiation and delithiation process. This material shows promising potential for use in high-rate anodes for lithium-ion batteries.

Electrochemical lithium storage of a ZnFe2O4/graphene nanocomposite as an anode material for rechargeable lithium ion batteries

In the present work, a graphene-based ZnFe2O4 nanocomposite has been synthesized using urea-assisted auto combustion synthesis followed by an annealing step. Urea synthesis is attractive, as it can rapidly synthesize materials with a high degree of control of particle size and morphology at low cost. The microstructure images clearly show that the ZnFe2O4 nanoparticles are homogeneously anchored on the surface of the graphene nanosheets. The average nanoparticle size ranges from 25–50 nm for both samples. As anode materials for lithium ion batteries, the obtained nanocomposite electrode shows significantly improved lithium storage properties with a high reversible capacity, excellent cycling stability and higher rate capability compared to the pure ZnFe2O4 nanoparticle electrode. The enhanced electrochemical performance of the nanocomposite sample can be attributed to the synergistic interaction between the uniformly dispersed ZnFe2O4 nanoparticles and the graphene nanosheets, which offers a large number of accessible active sites for the fast diffusion of Li+ ions, low internal resistance and more importantly accommodates the large volume expansion/contraction during cycling.

Sintering effects on dielectric properties of Zn-doped CaCu3Ti4O12 ceramic synthesized by modified sol-gel route

CaCu2.90Zn0.10Ti4O12 ceramic was synthesized by a novel semi-wet route and calcined at 800°C in air for 8 h. The obtained powder was divided into three parts and sintered in air at 950°C for 6 h, 8 h, and 12 h, separately. XRD results confirmed the single phase formation of all the sintered samples with similar cubic structure of CaCu3Ti4O12 (CCTO). Scanning electron micrographs of the CaCu2.9Zn0.1Ti4O12 ceramic sintered for 6 h shows bimodal grain size distribution. Increasing the sintering time significantly promotes the grain growth and microstructural densification. The sintering duration was found to have tremendous influence on microstructure and dielectric properties of CaCu2.90Zn0.10Ti4O12 ceramic. The CaCu2.9Zn0.1Ti4O12 ceramic sintered for 12 h exhibited high dielectric constant εr ∼ 5971 at 1 kHz and room temperature. It is found that εr is independent at high frequency and weakly dependent on temperature.

Dielectric properties of CaCu2·9Co0·1Ti4O12 and CaCu3Ti3·9Co0·1O12 ceramics synthesized by semi-wet route

The effect of Co + 2 doping on Cu + 2 and Ti + 4 sites in calcium copper titanate, CaCu3Ti4O12, has been examined. The doped compositions, CaCu

Dielectric behavior of CaCu3Ti4O12 electro-ceramic doped with La, Mn and Ni synthesized by modified citrate-gel route

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Partially reduced Co3O4/graphene nanocomposite as an anode material for secondary lithium ion battery

Co

High rate capability and long cycle stability of Co3O4/CoFe2O4 nanocomposite as an anode material for high-performance secondary lithium ion batteries

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Facile approach to synthesize CuO/reduced graphene oxide nanocomposite as anode materials for lithium-ion battery

Ti4O12 and CaCu3Ti

Simple synthesis and particle size effects of TiO2 nanoparticle anodes for rechargeable lithium ion batteries

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