Synthesis and performance of LiMn{sub 0.7}Fe{sub 0.3}PO{sub 4} cathode material for lithium ion batteries
- School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China)
Pure and carbon-containing olivine LiMn{sub 0.7}Fe{sub 0.3}O{sub 4} were synthesized at 600 deg. C by the method of solid-state reaction. Structure, surface morphology and charge/discharge performance of LiMn{sub 0.7}Fe{sub 0.3}O{sub 4} were characterized by X-ray diffraction, scanning electron microscopy, and electrochemical measurement, respectively. The prepared materials with and without carbon both show the single olivine structure. The morphologies of primary particles are greatly affected by the addition of carbon. Large particles (500-1000 nm) and densely sintered blocks were observed in pure LiMn{sub 0.7}Fe{sub 0.3}PO{sub 4}, which made the insertion and extraction of lithium ions difficult. Battery made from this sample can not charge and discharge effectively. The carbon-containing LiMn{sub 0.7}Fe{sub 0.3}PO{sub 4} has a small particle size (100-200 nm) and a regular appearance. This material demonstrates high reversible capacity of about 120 mAh g{sup -1}, perfect cycling performance, and excellent rate capability. It is obvious that the addition of carbon plays an important role in restricting the particle size of the material, which helps to prepare LiMn{sub 0.7}Fe{sub 0.3}PO{sub 4} with excellent electrochemical performance. The electrochemical reaction resistance is much lower in the partly discharged state than in the fully charged or fully discharged state by the measurement of ac impedance for carbon-containing LiMn{sub 0.7}Fe{sub 0.3}PO{sub 4}. It is indicated that the mixed-valence of Fe{sup 3+}/Fe{sup 2+} or Mn{sup 3+}/Mn{sup 2+} is beneficial to the transfer of electron which happens between the interface.
- OSTI ID:
- 20891588
- Journal Information:
- Materials Research Bulletin, Vol. 40, Issue 9; Other Information: DOI: 10.1016/j.materresbull.2005.04.020; PII: S0025-5408(05)00142-X; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
- Country of Publication:
- United States
- Language:
- English
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