High-voltage cycling doped LiCoO2 has been synthesized using the solid-state technique and it is observed that LiMn0.05C00.95O2 delivered a capacity of ∼160 mA·h/g after 50 cycles in the voltage range 3.5−4.5V.

Substituted cobalt oxides, LiM 0.05 Co 0.95 O 2 (M ϭ Mg 2ϩ , Al 3ϩ , and Ti 4ϩ), have been synthesized using solid-state technique and their performance in a 2032-type lithium rechargeable coin cell is reported. The synthesized powders were structurally analyzed using X-ray diffraction ͑XRD͒ and the surface morphology evaluated with scanning electron microscopy. XRD patterns indicate that single-phase materials were formed involving Al-doped LiCoO 2. Electrochemical studies were carried out in the voltage range 3.5-4.5 V ͑vs. Li metal͒ using 1 M LiPF 6 in ethylene carbonate/dimethyl carbonate as electrolyte. The doping involving 5% Mg resulted in a charge/discharge capacity of ϳ160 mAh/g at C/5 rate and remained stable even after 50 cycles. To the best of our knowledge, this is the first time that such high stable capacities have been obtained involving doped LiCoO 2 when cycled up to 4.5 V.

Lithium cobalt oxides doped with metal ions of the type LiM0.05C0.95O2 (M = Sn, Cr, Bi, and Zr) have been synthesized using a solid-state technique, and X-ray diffraction and SEM patterns have been evaluated. High stable capacities of ∼155 mAh/g at C/5 were obtained with Zr-doped LiCoO2 when cycled up to 4.5 V and have not been reported previously.