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Xia Y.-F.,Harbin Institute of Technology | Nie M.,Harbin Normal University | Wang Z.-B.,Harbin Institute of Technology | Yu F.-D.,Harbin Institute of Technology | And 4 more authors.
Ceramics International | Year: 2015

Layered structure LiNi0.6Co0.2Mn0.2O2 cathode material was synthesized via a two-step solid state reaction with industrial Ni0.6Co0.2Mn0.2(OH)2 and Li2CO3 in this paper. The samples prepared at different sintering temperatures (750-850°C) and sintering times (10-18h) were analyzed by physical and electrochemical methods to gain the optimal sintering condition, and an additional XRD Rietveld refinement was taken to get more reliable structural parameters. The results demonstrated that the higher temperature leads to larger primary particle size and severer agglomeration, while duration factor may affect the electrochemical performance rather than the structure and morphology of the materials. The optimized NCM622 material has an initial discharge capacity of 156.3mAhg-1 at 1C, whose capacity retention even reached 102.9% after 100 cycles. In addition, the three dispersed peaks (P1, P2, P3) in particle distribution analysis and R SEI, R e, R ct in electrochemical impedance spectroscopy have been separated and discussed in detail. © 2015 Elsevier Ltd and Techna Group S.r.l.

Zhang Y.,Harbin Institute of Technology | Wang Z.-B.,Harbin Institute of Technology | Nie M.,Harbin Normal University | Yu F.-D.,Harbin Institute of Technology | And 5 more authors.
RSC Advances | Year: 2016

Electrode materials with high tap densities and high specific volumetric energies are the key to large-scale industrial applications for the lithium ion battery industry, which faces huge challenges. LiNi0.5Co0.2Mn0.3O2 cathode materials with different particle sizes are used as the raw materials to study the effect of the mass ratio of mixed materials on the tap density and electrochemical performance of mixed materials in this work. Physical and electrochemical characterizations demonstrate that the tap density of mixed powders with different particle sizes is higher than those of materials with a single particle size. The tap density of as-prepared material has a decreasing trend with the increase of the ratio of 9 μm sized particle in the materials. The highest tap density among all of the kinds of materials reaches up to 2.66 g cm-3. Besides, the mixed material with a mass ratio of 7:2:1 has a bigger specific surface area and it presents better cycle behaviors and rate capability than other materials. The specific volumetric capacity of this mixed sample reaches up to 394.3 mA h cm-3 with 1C rate charge/discharge, and it has improvements of 8.5%, 22.2% and 40.6% over any single particle size of 9 μm, 6 μm and 3 μm, respectively, which contributes to the industrial production of Li-Ni-Co-Mn-O cathode materials for lithium ion batteries. This journal is © The Royal Society of Chemistry 2016.

Li S.-Y.,Harbin Engineering University | Chen M.,Harbin Engineering University | Xue Y.,Harbin Institute of Technology | Wu J.,Xian Huijie Industrial Co. | And 2 more authors.
Ionics | Year: 2015

The effects of Cr3+ doping and citric acid combustion on the electrochemical properties of Li4Ti5O12 were systematically investigated. The solid-state reaction process was used to synthesize four samples marked as LTO, C-LTO, LT-Cr-O, and C-LT-Cr-O, respectively. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) techniques were employed to study their structures and morphologies. The cyclic voltammetry (CV) tests, electrochemical impedance spectroscopy (EIS) analysis, and charge–discharge cycling were performed to study their electrochemical performance. The experimental results showed that the C-LT-Cr-O sample exhibited the advantages both of the Cr3+ doping and the citric acid combustion, presented high ordered morphology and high phase purity, and displayed a discharge capacity of 101.3 mAh g−1 with about 91.8 % capacity retention after 1000 cycles at 10C discharge rate. Therefore, the C-LT-Cr-O material is a promising anode material to be used in lithium ion batteries. [Figure not available: see fulltext.] © 2015, Springer-Verlag Berlin Heidelberg.

Lv Y.-Z.,Harbin Engineering University | Jin Y.-Z.,Harbin Engineering University | Xue Y.,Harbin Institute of Technology | Wu J.,Xian Huijie Industrial Co. | And 2 more authors.
RSC Advances | Year: 2014

LiNi0.5Mn1.5O4 cathode material has been synthesized by a solid-state reaction designedly using industrial raw materials (Li2CO3, NiO and electrolytic MnO2) in bulk scale, which are all used without further purification. The aim is to find the optimal preparation process of LiNi0.5Mn1.5O4 material for commercial application. The synthesis temperatures are adjusted to form a disordered Fd3m structure at 800-950°C for 12 h and then at 600°C for 6 h. Meanwhile, some powders have also been calcined at 850°C for 8-14 h and next annealed at 600°C for 6 h. XRD patterns, SEM micrographs and distribution curves of particle size shows that the LiNi0.5Mn 1.5O4 cathode material calcined at 850°C for 12 h and then annealed at 600°C for 6 h exhibits the best crystallinity, crystal shape as well as the best normal distribution. Electrochemical tests show that the LiNi0.5Mn1.5O4 material synthesized at 850°C for 12 h and then annealed at 600°C for 6 h has the highest capacity and excellent rate capability. After 200 cycles, the capacity retentions of the sample at 1, 2 and 5 C are as high as 97.8%, 98.5% and 98.0% of its initial capacities (120.8, 118.1 and 111.2 mA h g-1), respectively. The fundamental findings in this work can be applied to guide the synthesis of spinel LiNi0.5Mn1.5O4 as high performance electrode materials for lithium ion batteries, especially for industry. © 2014 the Partner Organisations.

Yu F.-D.,Harbin Institute of Technology | Wang Z.-B.,Harbin Institute of Technology | Chen F.,Harbin Institute of Technology | Wu J.,Xian Huijie Industrial Co. | And 2 more authors.
Journal of Power Sources | Year: 2014

Li, Al co-doped LiMn2O4 (Li1+xMn 2-x-yAlyO4, © 2014 Elsevier B.V. All rights reserved.

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