Lithium batteries are rechargeable energy storage devices that are commonly used in electronic devices such as cell phones, laptops, and electric vehicles. They are made of lithium metal or lithium compounds and use lithium ions to transfer their energy. This makes them lightweight, compact, and able to hold a large amount of energy. They have a high energy density, meaning they can store a lot of energy in a small space. However, they can be volatile if not used or stored properly, and can experience performance decreases over time. Despite this, their widespread use and continuous technological advancements have made them a popular choice for powering portable devices.