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1. 제 목 : LiFePO4 Nanocrystals for High-Power Li-Ion Batteries

2. 일 시 : 2010년 5 월 4 일 (화) 15:30-16:30

3. 연 사 : 정성윤 교수 (인하대학교 신소재공학부)

4. 장 소 : 301동 1512-2호

5. 연사약력 :
1995 : (B.S.) Inha University, Materials Sci. & Eng.
1995~1997 : (M.S.) KAIST, Materials Sci. & Eng.
1997~2001 : (Ph.D.) KAIST, Materials Sci. & Eng.
2001~ 2003 : Post doctoral fellow, MIT
Currently : Associate professor, Materials Sci. & Eng., Inha University

6. 내용요약 :
Olivine-type lithium metal phosphates have attracted a great deal of attention over the last decade as an alternative cathode material in Li-ion batteries. In particular, to improve the electrochemical performance of LiFePO4, numerous investigations have been made in addition to many studies of the intrinsic ionic and electronic properties and the thermodynamic phase equilibria. The achievement of remarkable high-rate capability and outstanding thermochemical stability in LiFePO4 during the intercalation reaction (S.-Y. Chung et al., Nature Mater., 1, 123 (2002)) have resulted in the recent success of the application as a safe power source adopted for power tools and potentially for hybrid electric vehicles as well (Nature, 444, 16 (2006)).
Among a variety of factors that govern the electrochemical cycling behavior in this class of compounds, control of the particle size and its distribution is recognized to be of great significance for charge and discharge reactions at high rates. Considering the one-dimensional nature of Li ion diffusion in the lattice based on previous studies, synthesis of the nanostructured phosphates is necessary to minimize the effective diffusion length of Li ions as well as to maximize the surface area of the particles for the enhancement of the mass and charge transport across interfaces for a limited time. Therefore, understanding of the exact mechanism of nanocrystal formation and relevant phase transformation in these olivines is a crucial step toward the achievement of a higher power density with a sufficient energy density in the electrochemical cells. By utilizing in-situ high-resolution electron microscopy (HREM) along with a hot-stage specimen holder, the initial stage of nucleation and growth of LiFePO4 nanocrystals at high temperatures in real time are directly observed (S.-Y. Chung et al., Nature Phys. 5, 68 (2009)). More details for atomic-scale probing of crystallization and resulting nanocrystal formation in LiFePO4 will be discussed.

7. 문 의 : 기계항공공학부 차석원 교수(☏ 880-1700)