Lithium-ion batteries are rechargeable energy storage devices commonly used in portable electronics, electric vehicles, and renewable energy systems. They work by moving lithium ions between the positive and negative electrodes during charging and discharging, which generates electrical energy. These batteries are popular due to their high energy density, lightweight design, and ability to retain charge over time. The main components of a lithium-ion battery include the anode, cathode, electrolyte, and separator. The anode is typically made of graphite, while the cathode often consists of lithium metal oxides. Safety features are also important, as overheating or damage can lead to risks such as fires or explosions.