| Charge/Discharge Mechanism of Multicomponent Olivine Cathode for Lithium Rechargeable Batteries |
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Young-Uk Park, R.A. Shakoor, Kyu-Young Park, Ki-Suk Kang |
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Department of Materials Science and Engineering, Seoul National University;Department of Materials Science and Engineering and KAIST Institute for Eco-Energy, KAIST;Department of Materials Science and Engineering and KAIST Institute for Eco-Energy, KAIST;Department of Materials Science and Engineering, Seoul National University; |
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| Abstract |
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Quasi-equilibrium profiles are analyzed through galvanostatic intermittent titration technique (GITT) and potentiostatic intermittent titration technique (PITT) to study the charge/discharge mechanism in multicomponent olivine structure ($LiMn_{1/3}Fe_{1/3}Co_{1/3}PO_4$). From GITT data, the degree of polarization is evaluated for the three regions corresponding to the redox couples of $Mn^{2+}/Mn^{3+}$, $Fe^{2+}/Fe^{3+}$ and $Co^{2+}/Co^{3+}$. From PITT data, the current vs. time responses are examined in each titration step to find out the mode of lithium de-intercalation/intercalation process. Furthermore, lithium diffusivities at specific compositions (x in $Li_xMn_{1/3}Fe_{1/3}Co_{1/3}PO_4$) are also calculated. Finally, total capacity ($Q^{total}$) and diffusional capacity ($Q^{diff}$) are obtained for some selected voltage steps. The entire study consistently confirms that the charge/discharge mechanism of multicomponent olivine cathode is associated with a one-phase reaction rather than a biphasic reaction. |
| Keywords:
Multicomponent olivine cathode, GITT, PITT, Cottrel-type, One-phase reaction |
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