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

Abstract LiCo 1− x Mg x O 2 ( 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 LiCoO 2 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 LiCoO 2 pronouncedly improved the cycling performance of samples although it slightly decreased the initial discharge capacity. LiCo 0.97 Mg 0.03 O 2 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 LiCoO 2 by suppressing the phase transition of the cathode during lithium ion deintercalation and intercalation.