Comparative studies on potential dependent electrochemical impedance spectroscopy of cathode material 0.5Li2MnO3·0.5LiNi0.5Mn0.5O2 for the initial two charging cycles

• More evidence about the complicated “structurally integrated” feature of 0.5Li2MnO3·0.5LiNi0.5Mn0.5O2.
• Reveal the structural evolution in the initial and second charging process.
• Strongly potential dependent EIS spectrum and the explanation.

Cathode material 0.5Li2MnO3·0.5LiNi0.5Mn0.5O2 is successfully synthesized by citrate acid assisted sol–gel method and shows pretty good electro-chemical performance. To elucidate the electro-chemical reactions and charge carrier transportation kinetics in the charge–discharge process, series of electro-chemical impedance spectra for the first and the second charge process are measured on multiple given state of charges. The rapid augmentation of resistance to electronic conduction and ionic conduction within the voltage range 4.45–4.6 V where the removal of Li2O from Li2MnO3 component takes place gives us more evidence about the complicated “structurally integrated” feature of this material. The relatively large span of the arc responsible for electronic conduction and the extremely large Mn3+ related charge transfer resistance at the beginning of the second charging indicate that after one complete charge–discharge cycle, Li2MnO3 and LiNi0.5Mn0.5O2 domains still reserve its original structure and will keep its structure for the followed cycles.