Lithium batteries are rechargeable energy storage devices that use lithium ions to move between the positive and negative electrodes during charging and discharging. They are widely used in various applications, including smartphones, laptops, and electric vehicles, due to their high energy density and lightweight nature. These batteries have a longer lifespan compared to traditional batteries, such as nickel-cadmium or lead-acid batteries. They also charge quickly and can maintain their performance over many cycles, making them a popular choice for modern technology and renewable energy systems, like solar power storage.