Browsing by Author "Zhang, J"

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    Novel synthesis and thermal property analysis of MgO–Nd2Zr2O7 composite
    (Elsevier, 2016-11-15) Kong, L; Zhang, J; Maeda, Y; Blackford, MG; Li, S; Triani, G; Gregg, DJ
    MgO-Nd2Zr2O7composites with ratios of 50–70 vol% MgO were produced via a one-pot combustion synthesis. A suite of characterization techniques, including X-ray diffraction, scanning and transmission electron microscopy were employed to investigate the structural properties while dilatometry, simultaneous thermal analysis and laser flash analysis were used to characterize the thermal properties of the composites. Dense pellets were produced after sintering at 1400 °C with grain sizes between 200 and 500 nm for both phases. The thermal properties of the composites are similar to those produced using standard methods. The composite with 70 vol% MgO was found to have the highest thermal conductivity below 1000 °C, while above this temperature the thermal conductivity was found to be similar and independent of MgO content. This novel synthesis route produces materials which show significant improvements in homogeneity with smaller particle sizes when compared to current standard synthesis techniques without significantly reducing thermal conductivity. © 2016 Elsevier Ltd.
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    Simple synchronous dual-modification strategy with Zr4+ doping and CeO2 nanowelding to stabilize layered Ni-rich cathode materials
    (American Chemical Society, 2023-05-22) Liu, JK; Yin, ZW; Zheng, WC; Zhang, J; Deng, SS; Wang, Z; Deng, Li; Xie, SJ; Liu, ZK; Avdeev, M; Qu, F; Kan, WH; Zhou, Y; Li, JT
    A Ni-rich layered oxide, one promising cathode for lithium-ion batteries (LIBs), exhibits the advantages of low cost and high capacity but suffers from rapid capacity loss due to bulk structural instability and surface side reactions. Herein, a simple synchronous dual-modification strategy with Zr4+doping and CeO2nanowelding is proposed to address such issues. Utilizing the migration energy difference of Zr and Ce ions in layered structures, one-step high-temperature sintering of LiNi0.8Co0.1Mn0.1O2particles with Zr and Ce nitrate distributions enables simultaneous doping of Zr ions in the bulk and CeO2surface modification. Therein, Zr ions in the bulk occupying the Li sites can improve the Li+diffusion rate and stabilize the crystal structure, while CeO2on the surface provides nanowelding between the grain boundaries and resistance to electrolyte erosion. Theoretical calculations and a series of structure/composition characterizations (i.e., neutron scattering, in situ X-ray diffraction, etc.) validated the proposed strategy and its role in stabilizing the Ni-rich cathodes. The synergistic effect of Zr4+doping and CeO2nanowelding enables an impressive initial capacity of 187.2 mAh g-1(2.7-4.3 V vs Li/Li+) with 86.1% retention after 200 cycles at 1 C and rate capabilities of 146.6 and 127.3 mAh g-1at 5 and 10 C, respectively. Upon increasing the testing temperature to 60 °C, the dual-modified Ni-rich cathode exhibits an initial discharge capacity of 203.5 mAh g-1with a good retention of 80.8% after 100 cycles at 0.5 C. The present strategy utilizing the migration energy difference of metal ions to achieve synchronous bulk doping and surface modification will offer fresh insights to stabilize layered cathode materials for LIBs, which can be widely used in other kinds of batteries with various cathode materials. © American Chemical Society