Abstract
Olivine structure LiFePO4/C composite powders are synthesized as cathode materials for Li-ion batteries via a conventional solid-state reaction. Improvement in electrochemical performance has been achieved by using poly(vinyl alcohol) as the carbon sources for the as-prepared materials. The influence of the heat treatment on the physical and the electrochemical properties of LiFePO4/C materials is investigated. To examine the effect of added carbon content on the properties of materials, a one-step heat treatment has been employed with control of the PVA content in the precursor. Six samples were prepared with 0, 1, 3, 5, 10 and 30 wt.% PVA added to the raw materials. The particle size of LiFePO4 decreases as the carbon content increases. Materials with medium carbon contents have a small charge-transfer resistance and thus exhibit superior electrochemical performance. Interestingly, for a LiFePO4/C composite with a low PVA content, an unusual plateau at 4.3 V is observed. It is considered that this is due to the Fe3+/Fe4+ redox reaction of Fe3+ compounds that are present as an impurity. For samples with a high PVA amount, a thicker carbon coating provides an obstacle to improve the electrochemical properties.
Original language | English |
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Pages (from-to) | 1361-1368 |
Number of pages | 8 |
Journal | Journal of Power Sources |
Volume | 160 |
Issue number | 2 SPEC. ISS. |
DOIs | |
Publication status | Published - 2006 Oct 6 |
Bibliographical note
Funding Information:The authors are grateful for financial support from the Korea Science and Engineering Foundation (KOSEF), through the Research Center for Energy Conversion & Storage.
Keywords
- Carbon coating
- Cathode material
- Li-ion batteries
- LiFePO
- Olivine
- Poly(vinyl alcohol)
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Energy Engineering and Power Technology
- Physical and Theoretical Chemistry
- Electrical and Electronic Engineering