Detailed analysis of alternating current impedance data of LiMn 2O4 electrodes measured at several temperatures and potentials was carried out. The Nyquist plots generally consisted of semicircles corresponding to two time constants. However, at low temperatures (-10 to 10 C) and potential region between 3.90 and 4.20 V, three time constants were present. The third semicircle present at the middle to high frequency range was attributed to electronic resistance of LiMn2O4. Impedance parameters were evaluated using appropriate electrical equivalent circuits. From the temperature dependence of resistive parameters, activation energy values for the corresponding processes were calculated.
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Acknowledgement Financial support from India Science Lab, General Motors Global R&D, is gratefully acknowledged.
- Activation energy
- Cathode material
- Electronic resistance
- Lithium-ion battery