The electrochemical properties and thermal stability of surface fluorinated / carbon coated LiFePO4 cathode were investigated by using F2 and NF3 gasses. In case of carbon coated LiFePO4 fluorinated by using NF3 at 6.67 kPa (F1-LiFePO4), the discharge capacity was about 10% larger than that of untreated one. Also it exhibited the lowest resistance (Rct = 35.55 O) and largest exchange current density (i0 = 0.72 mA) from the EIS results. However, in case of carbon coated LiFePO4 fluorinated by using NF3 at 50.66 kPa (F2-LiFePO4), the electrochemical properties were negatively affected by the formation of some resistive fluoride films. In terms of thermal stability, the decomposition temperature (222.0 oC) of F1-LiFePO4 was 14 oC higher than that of untreated LiFePO4. Therefore, the surface fluorination by using NF3 led to the improvement of the electrochemical properties and thermal stability of LiFePO4.Figure 1 Nyquist plots of the LiFePO4/Li half cells containing with (A) untreated LiFePO4, (B) F1-LiFePO4, and (C) F2-LiFePO4.

Effects of surface fluorination on electrochemical properties and thermal stability of LiFePO<sub>4</sub> cathode for lithium ion batteries

248th National Meeting (2014)

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Effects of surface fluorination on electrochemical properties and thermal stability of LiFePO4 cathode for lithium ion batteries

Effects of surface fluorination on electrochemical properties and thermal stability of LiFePO₄ cathode for lithium ion batteries