LithiumCobaltOxid

Lithiumcobaltoxid is a chemical compound with the formula LiCoO2. It is a layered transition-metal oxide composed of alternating sheets of lithium ions and cobalt oxide octahedra. In the pristine material, cobalt is in the +3 oxidation state. The crystal structure is related to the layered α-NaFeO2 family, with lithium occupying octahedral sites between CoO6 layers. LiCoO2 exhibits good electrochemical stability within a limited voltage window and has historically been the most common active material in commercial lithium-ion battery cathodes.

Preparation of lithiumcobaltoxid is typically achieved by solid-state reaction of lithium precursors, such as Li2CO3, with cobalt oxide or cobalt carbonate. The mixture is fired at high temperatures, usually in the range of 700–1000°C in air, to promote diffusion and phase formation. In practice, small excesses of lithium or coating and doping methods may be used to compensate lithium loss and improve cycling stability, rate capability, and thermal performance.

Electrochemically, lithiumcobaltoxid functions as a cathode material by reversibly inserting and extracting lithium ions as the battery charges and discharges. During charging, Li+ is extracted, oxidizing cobalt from Co3+ toward Co4+. The material typically delivers a reversible capacity on the order of 140–150 mAh per gram, with a nominal operating voltage near 3.9 V versus Li/Li+. Capacity and structural stability can decline at high states of charge due to phase transitions and cation mixing.

Applications and considerations: LiCoO2 has powered many early and longstanding lithium-ion cells, particularly in portable electronics, because of its high energy density. However, concerns about cobalt supply, cost, and long-term safety have driven the development of nickel-rich and doped layered oxides, as well as alternative cathode chemistries.