• Title, Summary, Keyword: passivation film (or SEI)

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Studies on Formation of Passivation Film on KMFC Anode with Initial Charge Temperature (탄소 부극에서 초기 충전온도별 부동태 피막 형성에 대한 연구)

  • Park, Dong-Won;Kim, Woo-Seong;Choi, Yong-Kook
    • Applied Chemistry for Engineering
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    • v.16 no.4
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    • pp.507-512
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    • 2005
  • When carbon electrode is used as an anode in Li ion battery, passivation film forms on the electrode surface during the initial charge process due to so called Solid-Electrolyte Interphase (SEI). The passivation film formed by solvent decomposition during the initial charge process affects charge/discharge capacity. In this paper, 1 M $LiPF_6,EC:DEC$ (1 : 1, volume ratio) electrolyte with $Li_2CO_3$, at various temperatures, the electrochemical characteristics of passivation film formed on Kawasaki Mesophase Fine Carbon electrode surface were investigated by using chronopotentiometry, cyclic voltammetry, and impedance spectroscopy. Experimental observations indicated that as solvent decomposition occurred, the decomposition voltage was strongly dependent on ionic conductivity, which was low in the process at low temperature. The impedance of passivation film formed during the initial charge process, were dependent on the temperature.

Properties of Capacity on Carbon Electrode in EC:MA Electrolytes - I. Effect of Mixing Ratio on the Electrochemical Properties - (EC:MA 혼합전해질에서 카본 전극의 용량 특성 - I. 전기화학적 특성에 대한 혼합비의 영향 -)

  • Park, Dong-Won;Kim, Woo-Seong;Son, Dong-Un;Kim, Sung-Phil;Choi, Yong-Kook
    • Applied Chemistry for Engineering
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    • v.17 no.2
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    • pp.183-187
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    • 2006
  • The choice of solvents for electrolytes solutions is very important to improve the characteristics of charge/discharge in the Li-ion battery system. Such solvent systems have been widely investigated as electrolytes for Li-ion batteries. In this paper, the electrochemical properties of the solid electrolyte interphase film formed on carbon anode surface and the solvent decomposition voltage in 1 M LiPF6/EC:MA(x:y) electrolyte solutions prepared from the various mixing volume ratios are investigated by chronopotentiometry, cyclic voltammetry, and impedance spectroscopy. As a result, the solvent decomposition voltages are varied with the ionic conductivity of the electrolyte. Electrochemical properties of the passivation film were different, which are dependent on the mixture ratio of the solvents. Therefore, the most appropriate mixing ratio of EC and MA as a solvent in 1 M $LiPF_6/(EC+MA)$ system for Li-ion battery is approximately 1:3 (EC:MA, volume ratio).