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Xiang J.,Narada Power Source Co. | Li G.,Architectural Design and Research Institute of Zhejiang Province
Materials Science and Engineering B: Solid-State Materials for Advanced Technology | Year: 2013

Bud-like FeS2 powder was synthesized by a solvothermal method with the help of polyvinylpyrrolidone (PVP). The bud-like FeS2 microshperes with the diameters of 2.0-3.0 μm were consisted of the submicro-flakes with 0.5-1μm in width and length, and about 60 nm in thickness. As an anode material for Li-ion batteries, the bud-like FeS 2 delivered initial specific discharge capacity of 773 and 749 mAh g-1, and could sustain 387 and 368 mAh g-1 after 30 cycles at current densities of 45 and 89 mA g-1, respectively, much higher than the solid one obtained without PVP. The bud-like FeS2 microshperes also showed large diffusion coefficient of Li-ions ( DLi+) calculated by Galvanostatic intermittent titration (GITT). The improved electrochemical performance of bud-like FeS2 was due to the unique structure which provides large contact area between the FeS2 microspheres and electrolyte, decreased polarization and large DLi+, leading to enhanced electrode reaction kinetics. © 2013 Elsevier B.V. Source

Lu Y.,Zhejiang University | Wang X.,Zhejiang University | Mai Y.,Zhejiang University | Xiang J.,Narada Power Source Co. | And 5 more authors.
Journal of Physical Chemistry C | Year: 2012

Hybridizing Ni 2P/graphene sheet composite is successfully accomplished via a one-pot solvothermal method. As anode materials for lithium-ion batteries, the Ni 2P spheres with sizes of 10-30 nm can effectively prevent the agglomeration of graphene sheets. In turn, the graphene sheets with good electrical conductivity serve as a conducting network for fast electron transfer between the active materials and charge collector, as well as buffered spaces to accommodate the volume expansion/contraction during cycling. The cyclic stability and rate capability of Ni 2P are significantly improved after the incorporation of graphene sheets. After 50 cycles, the Ni 2P/graphene sheet hybrid delivers a capacity of 450 mA h g -1 and 360 mA h g -1 at a current density of 54.2 and 542 mA g -1, respectively. The voltage hysteresis of Ni 2P with and without graphene sheets is also discussed. The incorporation of graphene sheets can partly decrease the voltage polarization, and modify the thickness of solid electrolyte interface (SEI) film. © 2012 American Chemical Society. Source

Song S.G.,Zhejiang University of Technology | Li X.P.,Narada Power Source Co.
Environment, Energy and Applied Technology - Proceedings of the 2014 3rd International Conference on Frontier of Energy and Environment Engineering, ICFEEE 2014 | Year: 2015

In order to solve the problem of energy efficiency during electric vehicles regenerative braking, according to regenerative braking energy and energy flow process, the key factors affecting the regenerative braking was analyzed. The regenerative braking efficiency evaluation index was proposed considering braking control, mechanical transmission, motor and battery combined efficiency. Analysis of the motor braking torque, speed and battery SOC for energy recovery efficiency test, based on experiment data to fit curve of motor and battery combined efficiency, and established energy recovery efficiency model. With conventional braking were simulated, obtained the regenerative braking efficiency under different working conditions, and verified regenerative braking efficiency model. © 2015 Taylor & Francis Group, London. Source

Zhang D.,Hang Zhou City of Quality and Technical Supervision and Testing Institute | Xiang J.,Narada Power Source Co. | Zhu Y.,Hang Zhou City of Quality and Technical Supervision and Testing Institute | Li G.,Architectural Design and Research Institute of Zhejiang Province | And 6 more authors.
Journal of Nanoscience and Nanotechnology | Year: 2014

Porous and solid FeS2 particles are both synthesized via solid-state reaction method using FeC2O4 · 2H 2O and S powder as the raw materials. The difference of the mophology is adjusted by the calcination time. The porous FeS2 electrode exhibits significantly improved and less improved electrochemical performance comparing to the solid one during the initial 15 cycles and the later cycling process, respectively. The significantly improvement in the initial 15 cycles is due to the large surface area and 3D conducting network of the porous structure, which provides large active electrochemical interface of the active particles and electrolyte, and shortens the path length for Li+ transport. The less improvement during the later cycling process is attributed to the unstable porous structure, which collapses into nanoparticles after long cycles. On the basis of the analysis, a theoretical proposal to optimize the structure of FeS2 electrode is provided.© 2014 American Scientific Publishers. Source

Lu Y.,Zhejiang University | Tu J.P.,Zhejiang University | Xiang J.Y.,Narada Power Source Co. | Wang X.L.,Zhejiang University | And 3 more authors.
Journal of Physical Chemistry C | Year: 2011

Hierarchical, nanostructured nickel phosphide (h-Ni2P) spheres are synthesized by a one-pot reaction from an organic-phase mixture of nickel acetylacetonate, trioctylphosphine, tri-n-octylamine, and oleylamine (OAm). OAm is used as a surfactant to modify the surface morphology of Ni2P spheres. The h-Ni2P spheres are composed of ordered nanoparticles with 5-10 nm sizes and filled by amorphous carbon. The hierarchical structure can greatly increase the contact area between Ni2P and electrolyte, which provides more sites for Li+ accommodation, shortens the diffusion length of Li+, and enhances the reactivity of the electrode reaction. Also, the amorphous carbon and the hierarchical Ni2P nanostructures can buffer volume expansion and thus increase the electrode stability during cycling. In the context of storage behavior, the h-Ni 2P electrode exhibits high capacity as well as Coulombic efficiency. After 50 cycles, the reversible capacity of h-Ni2P spheres is 365.3 mA h g-1 at 0.5 C and 257.8 mA h g-1 at 1 C, much higher than that of Ni2P spheres (97.2 mA h g-1 at 0.5 C). At a high rate of 3 C, the specific capacity of h-Ni2P is still as high as 167.1 mA h g-1. © 2011 American Chemical Society. Source

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