Synthesis of star-like MnO2-CeO2/CNT composite as an efficient cathode catalyst applied in lithium-oxygen batteries

A MnO2-CeO2/CNT nanostructure is synthesized using hydrothermal method for which the amounts of CNT, CeO2 and MnO2 are determined using TGA and ICP-OES analysis equal to 55%, 25% and 20%, respectively. The MnO2-CeO2/CNT nanocomposite is characterized using SEM, EDS-SEM, XRD, BET, TGA and ICP techniques and used as an efficient cathodic electrocatalyst in the lithium-oxygen battery. The energy storage capacity of the lithium-oxygen battery fabricated using pristine CNT is about 4100 mA.h/gelectrode at 100 mA/gelectrode current density but that of MnO2-CeO2/CNT nanocatalyst is 7980 mA.h/gelectrode at the 50 mA/gelectrode current density and 6860 mA.h/gelectrode at the 100 mA/gelectrode current density showing a 68% improvement in the battery performance. The charge and discharge over-voltages are 0.68 and 0.20 V, respectively, for MnO2-CeO2/CNT while they are 1.44 and 0.32 V for CNT, respectively, at the 100 mA/gelectrode current density exhibiting 52% and 37.5% decrease in charge and discharge over-voltages. The cyclic performance of the MnO2-CeO2/CNT nanostructure cathode is considered at 70 cycles reflecting its appropriate performance. The electrochemical impedance spectroscopy (EIS) illustrates a suitable reversibility for the synthesized cathode in such a way that the resistance created at discharge is diminished at the charging process.

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