Lithium Cobalt Oxide (LiCoO2) has been used as a cathode material since the time lithium-ion batteries were first introduced for portable devices. “LCO,” as it is also known, has a layered structure (as opposed to Lithium Manganese Oxide or Lithium Nickel Manganese Oxide, which have a spinel structure). LCO is a very attractive cathode material because of its relatively high theoretical specific capacity (274 mAh g⁻¹), high theoretical volumetric capacity (1363 mAh cm⁻³), low self-discharge, high discharge voltage, and good cycling performance. The lithium ions are sandwiched between layers of CoO₂^– ions, and as a result, can easily de-intercalate and intercalate in the structure. However, only half the number of lithium ions in LiCoO₂ are available for the ‘roundtrip’, which limits the practical capacity of LCO to about 140 mAh/g.

Cobalt, which was the first transition metal to be used in a lithium-ion battery metal oxide cathode more than three decades ago, is still used in select applications (e.g., rechargeable batteries in portable devices). The availability of cobalt is far more restricted than other transition elements such as iron, manganese, and nickel. This is one reason NMC materials are used in bulk high capacity Lithium-ion batteries instead. Also, the thermal stability of LCO is somewhat limited, which leads to decomposition and generation of oxygen.