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- Title
Improving the rate and low-temperature performance of LiFePO<sub>4</sub> by tailoring the form of carbon coating from amorphous to graphene-like.
- Authors
Hu, Qiao; Liao, Jia-Ying; Zou, Bang-Kun; Yu, Mu-Fan; Tang, Zhong-Feng; Wen, Zhao-Yin; Chen, Chun-Hua
- Abstract
A solid-state reaction process with poly(vinyl alcohol) as the carbon source is developed to synthesize LiFePO4-based active powders with or without modification assistance of a small amount of Li3V2(PO4)3. The samples are analyzed by X-ray diffraction, scanning/transmission electron microscopy, and Raman spectroscopy. It is found that, in addition to the minor effect of a lattice doping in LiFePO4 by substituting a tiny fraction of Fe2+ ions with V3+ ions, the change in the form of carbon coating on the surface of LiFePO4 plays a more important role to improve the electrochemical properties. The carbon changes partially from sp3 to sp2 hybridization and thus causes the significant rise in electronic conductivity in the Li3V2(PO4)3-modified LiFePO4 samples. Compared with the carbon-coated baseline LiFePO4, the composite material 0.9LiFePO4·0.1Li3V2(PO4)3 shows totally different carbon morphology and much better electrochemical properties. It delivers specific capacities of 143.6 mAh g−1 at 10 C rate and 119.2 mAh g−1 at 20 C rate, respectively. Even at the low temperature of −20 °C, it delivers a specific capacity of 118.4 mAh g−1 at 0.2 C.
- Subjects
LITHIUM alloys; AMORPHOUS substances; X-ray diffraction; TRANSMISSION electron microscopy
- Publication
Journal of Solid State Electrochemistry, 2018, Vol 22, Issue 3, p797
- ISSN
1432-8488
- Publication type
Article
- DOI
10.1007/s10008-017-3777-y