Improving the electrochemical behavior of LiCoO 2 electrode by mixed Zr–Mg doping

Abstract

A new class of LiCo 1− x Zr x/2 Mg x/2 O 2 ( 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 LiCo 1− x Zr x/2 Mg x/2 O 2 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 Li 2MgZrO 4 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.