Improvement of electrochemical properties of Ca3Co4O9 as anode materials for lithium-ion batteries by Cr doping

Electrochemical performance of the misfit-layered Ca3Co4O9 and Ca3Co3.9Cr0.1O9 anode material for lithium-ion batteries were investigated. The single phase of Ca3Co4O9 and Ca3Co3.9Cr0.1O9 powders were successfully synthesized by the thermal hydro-decomposition method. Both samples showed plate-like particle morphology. The particle size of the doped sample was almost twice larger than the size of Ca3Co4O9. By doping Cr, the electrochemical properties of Ca3Co3.9Cr0.1O9 were considerably improved compared to the undoped sample. The specific capacity of the doped sample increased with the number of cycle. After 100 cycles, the specific capacities of the undoped and doped sample were 280 and 513 mAh.g(-1), respectively, showing an increase of over 80 %. The high rate performance of the doped sample was also improved. The cyclic voltammetry measurements showed the enhanced reactivity, and the electrochemical impedance spectroscopy showed the reduced resistivity of the Cr-doped anode. The better electrochemical properties of Ca3Co3.9Cr0.1O9 were attributed to the formation of CoO, the enhanced reactivity, the good electrical conduction, and the reduction in volume changing.