Lithium Ion batteries are a type of rechargeable battery commonly used in portable electronics, electric vehicles, and renewable energy storage. They work by moving lithium ions between the positive and negative electrodes during charging and discharging, which allows for efficient energy storage and release. These batteries are popular due to their high energy density, lightweight design, and relatively low self-discharge rate. However, they require careful management to prevent overheating and degradation, making battery management systems essential for safety and longevity in devices like smartphones and laptops.