1. Field
One or more aspects of embodiments of the present invention are directed to a positive active material for a rechargeable lithium battery, a method of preparing the same, and a rechargeable lithium battery including the same.
2. Description of the Related Art
Rechargeable lithium batteries can be utilized as a power source for small portable electronic devices. Rechargeable lithium batteries typically include an organic electrolyte solution and therefore, may have at least twice the discharge voltage of a conventional battery utilizing an alkaline aqueous solution. Accordingly, rechargeable lithium batteries have high energy density.
A rechargeable lithium battery is typically manufactured by injecting an electrolyte solution into a battery cell, which includes a positive electrode including a positive active material capable of intercalating/deintercalating lithium ions and a negative electrode including a negative active material capable of intercalating/deintercalating lithium ions.
LiCoO2 has been widely utilized as the positive active material, but LiCoO2 has a high manufacturing cost, and the supply of LiCoO2 is unstable due to the scarcity of cobalt (Co). Accordingly, a low-cost positive active material including Ni (nickel) or Mn (manganese) has been researched.
However, while the positive active material including nickel is suitable for a high capacity and high voltage battery, it has unstable structure and weak thermal stability due to its reaction with the electrolyte solution and thus, may deteriorate the capacity of the battery.
On the other hand, an overlithiated oxide, for example, may increase the capacity of the battery, since lithium ions are released from the overlithiated oxide at a high voltage of greater than or equal to about 4.5 V. However, an overlithiated oxide may generate oxygen gas during the reaction and thus, may facilitate an irreversible reaction during which lithium ions get released and do not re-participate in the reaction.