Cobalt is commonly used in lithium-ion batteries, particularly in the form of lithium cobalt oxide (LiCoO₂) in the cathode. Cobalt helps stabilize the battery's structure and improve its performance by enhancing energy density, lifespan, and safety. In lithium-ion batteries, cobalt is often used in the form of cobalt oxide or cobalt salts. It contributes to a higher energy density, meaning the battery can store more energy relative to its size and weight. This helps in extending the battery life and improving overall efficiency. However, cobalt is also a material of concern due to its cost, ethical sourcing issues, and environmental impact.