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Ambient Hydrothermal Synthesis of Lithium Iron Phosphate and Its Electrochemical Properties in Lithium-ion Batteries

Lithium iron phosphate (LiFePO4) has been synthesized by hydrothermal synthesis using pyrrole as an efficient reducing agent. The oxidized Fe3+ in the system reacts with pyrrole that can form polypyrrole (PPy) to generate Fe2+. The PPy can also be a carbon source for further calcination. The observations of scanning electron microscope (SEM) and transmission electron microscope (TEM) show that the particle size of LiFePO4 is around 500 nm and a layer of carbon coats on LiFePO4. The chemical composition of the LiFePO4 was characterized by elemental analysis (EA) and inductively coupled plasma mass spectroscopy (ICP/MS). The results of TEM and X-ray diffraction (XRD) show the structure of LiFePO4 is orthorhombic olivine. Raman and X-ray photoelectron spectroscopy (XPS) results indicate that pyrrole as a reducing agent prevents the impurity of Fe3+ formation and the resulting polypyrrole plays a role as carbon source. The calcination of LiFePO4 greatly affects the energy density. In addition, the carbon contain in the LiFePO4 powder is controllable using the addition of Fe3+ to enhance the electrical conductivity. Moreover, the electrochemical results show the energy capacity of the hydrothermal LiFePO4 is 152 mAh g−1. The LiFePO4 has a better rate discharge capability compared with LiFePO4 synthesized with ascorbic acid as a reducing agent.

Identiferoai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0926111-195725
Date26 September 2011
CreatorsLiang, Yi-Ping
ContributorsDr. Mao-Sung Wu, Dr. Jyh-Tsung Lee, Dr. Yen-Nan Chiang
PublisherNSYSU
Source SetsNSYSU Electronic Thesis and Dissertation Archive
LanguageCholon
Detected LanguageEnglish
Typetext
Formatapplication/pdf
Sourcehttp://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0926111-195725
Rightsuser_define, Copyright information available at source archive

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