A lithium-ion battery is a type of rechargeable battery commonly used in portable electronics, electric vehicles, and renewable energy storage. It works by moving lithium ions between the positive and negative electrodes during charging and discharging, allowing for efficient energy storage and release. These batteries are popular due to their high energy density, lightweight design, and low self-discharge rate. They can be found in devices like smartphones, laptops, and tablets, making them essential for modern technology. However, they require careful handling and recycling to minimize environmental impact.