Jiangsu Cobalt Nickel Metal Co.

Taixing, China

Jiangsu Cobalt Nickel Metal Co.

Taixing, China
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Kong J.-Z.,Nanjing University of Aeronautics and Astronautics | Kong J.-Z.,Nanjing University | Zhai H.-F.,Henan Normal University | Ren C.,Nanjing University of Aeronautics and Astronautics | And 6 more authors.
Journal of Solid State Electrochemistry | Year: 2014

Quasi-spherical (Ni0.5Co0.2Mn0.3)(OH) 2 precursor is prepared via a continuous hydroxide co-precipitation method using sodium lactate as the green chelating agent. A layered structure Li(Ni0.5Co0.2Mn0.3)O2 is synthesized by calcining the mixture of as-prepared precursor and Li2CO 3 in air. X-ray photoelectron spectroscopy (XPS) indicates that Ni, Co, and Mn exist in the oxidation states of +2/+3, +3 and +4, respectively. The influence of calcination temperature on the structural, morphological, electrochemical properties of Li(Ni0.5Co0.2Mn 0.3)O2 oxides are investigated in detail. As a result, the sample calcined at 850 C shows excellent electrochemical performance, which could be ascribed to its good crystal structure, low cation disorder, appropriate crystallinity. This sample delivers an initial discharge capacity of 192.6 mA h g-1 with a coulombic efficiency of 89.5 % at a current density of 20 mA g-1, and exhibits good rate capability and stable cyclability. Finally, the electrochemical performance of the sodium lactate-derived sample is briefly compared with those of the oxalic acid-derived and ammonia-derived oxide. © 2013 Springer-Verlag Berlin Heidelberg.


Kong J.-Z.,Nanjing University of Aeronautics and Astronautics | Kong J.-Z.,Jiangsu Precision and Micro Manufacturing Technology Laboratory | Kong J.-Z.,Nanjing University | Ren C.,Nanjing University of Aeronautics and Astronautics | And 8 more authors.
Journal of Solid State Electrochemistry | Year: 2016

Li2TiO3 is used as a novel coating material to modify Li(Li0.2Mn0.51Ni0.19Co0.1)O2 electrode to enhance the electrochemical performance of the host material. After coating, the significant improvements in the initial Coulombic efficiency, rate capability, and cyclic performance are achieved at room temperature. Particularly, the sample coated with 3 wt% Li2TiO3 exhibits the highest rate capability (169.9 mAh g−1 at 2 C rate and 149.1 mAh g−1 at 5 C rate), best cycleability (discharge capacity of 207.1 mAh g−1 at 0.5 C after 100 cycles), and improved initial Coulombic efficiency (69.5 %) in the voltage range of 2.0–4.8 V. The charge–discharge curves reveal that the effective Li-ion-conductive Li2TiO3 coating layer could stabilize the host structure, protect the electrode surface from F− ion attack, and prevent the undesired surface side reactions on the electrode surface. Meanwhile, the electrochemical impedance spectroscopy (EIS) tests prove that the appropriate Li2TiO3 coating layer can effectively suppress the increasing impedance of the host electrode. © 2016 Springer-Verlag Berlin Heidelberg


Kong J.-Z.,Nanjing University of Aeronautics and Astronautics | Kong J.-Z.,Nanjing University | Zhai H.-F.,Nanjing University | Ren C.,Nanjing University of Aeronautics and Astronautics | And 6 more authors.
Journal of Alloys and Compounds | Year: 2013

Macroporous LiNi0.5Co0.2Mn0.3O2 particles were prepared by a modified sol-gel method based on resorcinol and formaldehyde. The influence of annealing temperature on the physical and electrochemical performance was investigated. Among these oxides, 800 °C-annealed LiNi0.5Co0.2Mn0.3O2 with good crystallinity delivers the highest value of integrated intensity I(003)/I(104) and the lowest value of (I( 006)+I(102))/I(101), implying that this sample has the least cation mixing and best hexagonal ordering. This sample exhibits a high initial discharge capacity of 167.9 mAh/g tested at 50 mA/g, the largest capacity retention of 92.1% after 50 cycles at 300 mA/g, and the highest discharge capacity of 138.2 mAh/g at 1000 mA/g. The excellent electrochemical performance of this oxide is attributed to its well crystallinity, high cation ordering, and good hexagonal ordering. © 2013 Elsevier B.V. All rights reserved.


Kong J.-Z.,Nanjing University of Aeronautics and Astronautics | Zhou F.,Nanjing University of Aeronautics and Astronautics | Wang C.-B.,Nanjing University of Aeronautics and Astronautics | Yang X.-Y.,Nanjing University of Aeronautics and Astronautics | And 5 more authors.
Journal of Alloys and Compounds | Year: 2013

Spherical Ni0.5Co0.2Mn0.3(OH)2 precursor was prepared via co-precipitation method using oxalic acid as chelating agent. And layered structure Li(Ni0.5Co 0.2Mn0.3)O2 cathode materials were synthesized by calcining the mixture of different lithium salts and hydroxide precursor (Ni0.5Co0.2Mn0.3)(OH)2 at the temperatures ranged from 800 to 900 °C. The effects of the Li source and calcination temperature on physical and electrochemical properties of the electrode samples were deeply investigated. And Li2CO3 is considered to be the suitable Li source for the synthesis of Li[Ni 0.5Co0.2Mn0.3]O2. The results also show the sample calcined at 850 °C gives the highest integrated intensity ratio I(003)/I(104), indicating that this sample has the lowest amount of cation mixing. At the same time, this sample shows excellent electrochemical properties, such as the largest initial discharge capacity of 176 mAh g-1 at 0.1 C, best cycle stability of about 100% at 0.2 C and highest rate capability. © 2012 Elsevier B.V. All rights reserved.


Kong J.-Z.,Nanjing University of Aeronautics and Astronautics | Kong J.-Z.,Nanjing University | Yang X.-Y.,Nanjing University of Aeronautics and Astronautics | Zhai H.-F.,Nanjing University | And 5 more authors.
Journal of Alloys and Compounds | Year: 2013

Hydroxide precursor Ni0.5Co0.2Mn0.3(OH) 2 with average particle size of about 9.88 lm was prepared via co-precipitation method using oxalic acid as an ammonia-free chelating agent. Well-ordered layer-structured LiNi0.5Co0.2Mn 0.3O2 was synthesized with controlling the Li/(Ni + Co + Mn) molar ratio by calcining the uniform metal hydroxide with Li 2CO3 at 850 °C. The effect of excessive Li on the structural and electrochemical properties of the final compounds Li 1+x(Ni0.5Co0.2Mn0.3)O2 (0 6 x 0.2) was deeply investigated. Excessive Li is favorable to suppress the degree of cation mixing and improve the hexagonal ordering, indicated by the improved value of I(1 0 3)/I(1 0 4) and the decreased value of (I(0 0 6) + I(1 0 2))/ I(1 0 1). Higher discharge capacity, as well as better cyclability and rate capability, was achieved for the Li-excess Li1+x(Ni0.5Co 0.2Mn0.3)O2 compounds, especially the sample of Li1.1(Ni0.5Co0.2Mn0.3)O 2, compared with that of Li(Ni0.5Co0.2Mn 0.3)O2. It is believed that such enhanced electrochemical performances are related to the improved physical and structural properties of the Li-excess samples. © 2013 Elsevier B.V. All rights reserved.

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