Key Laboratory for New Type of Functional Materials in Hebei Province

Hebei, China

Key Laboratory for New Type of Functional Materials in Hebei Province

Hebei, China
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Ou X.,Hebei University of Technology | Ou X.,Key Laboratory for New Type of Functional Materials in Hebei Province | Gu H.,Hebei University of Technology | Wu Y.,Hebei University of Technology | And 2 more authors.
Electrochimica Acta | Year: 2013

Lithium iron phosphate (LFP) was prepared by hydrothermal synthesis in an organic-free system. Samples were collected at different time spots during temperature rising and soaking period and characterized by X-ray diffraction, scanning electron microscopy, B.E.T. specific surface area and particle size analysis. Two precursors, Li3PO4 and Fe 3(PO4)2·8H2O, form easily at ambient temperature. They dissolve into ions once temperature increases to 135 °C. LFP nuclei form rapidly at 135-140 °C and grow fast at 140-150 °C. The crystal morphology transforms from diamond to polygon plate at 150-160 °C. The B.E.T. specific surface area and particle size decrease as reaction time prolongs. The thickness of the platelets remains unchanged within the range of 60-100 nm for each LFP sample. The sample synthesized at 160 °C for 2 h and then coated with carbon (LFP/C-2) exhibits optimum electrochemical performances that the specific discharge capacities are 162.1, 150.8 and 136.9 mAh g-1 at 0.2 C, 1 C and 5 C, respectively. Reducing the precursors' particle size would be an effective way to shorten the reaction time and obtain fine particles with high specific surface area and high purity. © 2013 Elsevier Ltd.


Song Q.,Key Laboratory for New Type of Functional Materials in Hebei Province | Song Q.,Hebei University of Technology | Ou X.,Key Laboratory for New Type of Functional Materials in Hebei Province | Ou X.,Hebei University of Technology | And 6 more authors.
Materials Research Bulletin | Year: 2011

Lithium iron phosphate was prepared by hydrothermal synthesis using LiOH·H 2O, FeSO 4·7H 2O and H 3PO 4 as raw materials. The effects of pH value of reaction solution on particle morphology and electrochemical property were investigated. The pH value of the reaction solution was adjusted in the range of 2.5-8.8 by dilute sulfuric acid and ammonia water. The samples were characterized by field-emission scanning electronic microscope (FE-SEM), X-ray powder diffraction (XRD), constant-current charge/discharge cycling tests and chemical analysis. The results indicated that the particles exhibited acute angle diamond flake-like morphology at pH = 2.5, and as the pH value increased, the particle became hexagon flake-like, round flake-like and irregular flake-like morphology gradually. The optimal sample synthesized at pH = 6.4 exhibited discharge capacities of 151.8 mAh g -1 at 0.2 C rate and 129.3 mAh g -1 at 3 C rate. It was found that pH value affected the morphologies and properties of the product by means of different crystal growth rates. © 2011 Elsevier Ltd. All rights reserved.


Qi Y.,Hebei University of Technology | Qi Y.,Key Laboratory for new type of functional materials in Hebei Province | Cui C.,Hebei University of Technology | Cui C.,Key Laboratory for new type of functional materials in Hebei Province | And 3 more authors.
Advanced Materials Research | Year: 2013

Novel K2Ti6O13 nanowires were successfully synthesized by a new method, that is sol-gel/ hydrothermal combined method. The crystal structure and morphology of the products were characterized by a series of methods including XRD, SEM, EDX and TEM. The results indicate that the products synthesized are K2Ti6O13 nanowires. The diameter is about 5nm, and its length is in the range of from a few micrometers to hundreds of micrometers. The TiO2 nanoparticles synthesized via a sol-gel method, as hydrothermal reaction precursors, play an important decisive role on the diameter of K2Ti6O13 nanowires and the hydrothermal reaction rate. Photocatalytic degradation of MB in presence of the K2Ti6O13 nanowires was compared with that in presence of the TiO2 nanoparticles. The results show that the nanowires have better photocatalytic activity. © (2013) Trans Tech Publications, Switzerland.

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