Improving the electrochemical behavior of LiCoO2 electrode by mixed Zr-Mg doping

A new class of LiCo1−xZrx/2Mgx/2O2 (x = 0, 0.02, 0.06, 0.10, 0.20) materials has been synthesized using a solution-combustion method with mixed acetates/nitrates as the starting materials. The structure of the synthesized oxides was analyzed using X-ray diffraction (XRD). Iodometry titration was used to measure the oxidation state of cobalt. The electrochemical performance of LiCo1−xZrx/2Mgx/2O2 electrodes was analyzed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge cycling studies in the voltage range 2.7-4.2 V (versus Li metal). It is found that the maximum doping level (x) is around 0.06, above which Li2MgZrO4 is formed as an impurity phase. The use of combined Zr-Mg doping has resulted in the decrease of the electrode impedance and increase of the specific capacity and the stability of 3.6 V plateau efficiency.