Enhanced electrochemical performance of Mg-doped LiCoO2 synthesized by a polymer-pyrolysis method

LiCo1−xMgxO2(x=0, 0.01, 0.03, and 0.05) was synthesized by a polymer-pyrolysis method. The effect of Mg doping on the structure and electrochemical properties of LiCoO2 was investigated. XRD analysis showed that all the samples obtained had the well-ordered layer structure. SEM image showed that the powders consist of well-crystallized particles with hexagonal form. The charge–discharge tests showed that the increase of Mg content in LiCoO2 pronouncedly improved the cycling performance of samples although it slightly decreased the initial discharge capacity. LiCo0.97Mg0.03O2 demonstrated an initial discharge capacity of 169.2 mAh g−1 and the best cyclic performance as it retained 91.1% of the initial capacity after 50 cycles when cycled at 50 mA g−1 between 3.0 and 4.5 V. Cyclic voltammagram demonstrated that the Mg doping can distinctly stabilize the crystal structure of LiCoO2 by suppressing the phase transition of the cathode during lithium ion deintercalation and intercalation.