Synthesis and electrochemical performance of doped LiCoO2 materials

Layered intercalation compounds LiM0.02Co0.98O2 (M = Mo6+, V5+, Zr4+) have been prepared using a simple solid-state method. Morphological and structural characterization of the synthesized powders is reported along with their electrochemical performance when used as the active material in a lithium half-cell. Synchrotron X-ray diffraction patterns suggest a single phase HT-LiCoO2 that is isostructural to α-NaFeO2 cannot be formed by aliovalent doping with Mo, V, and Zr. Scanning electron images show that particles are well-crystallized with a size distribution in the range of 1–5 μm. Charge–discharge cycling of the cells indicated first cycle irreversible capacity loss in order of increasing magnitude was Zr (15 mAh g−1), Mo (22 mAh g−1), and V (45 mAh g−1). Prolonged cycling the Mo-doped cell produced the best performance of all dopants with a stable reversible capacity of 120 mAh g−1 after 30 cycles, but was inferior to that of pure LiCoO2.