Nickel-iron batteries are rechargeable batteries that use nickel oxide and iron as their main components. They are known for their durability and long lifespan, often lasting over 20 years with proper maintenance. These batteries can withstand deep discharges and are less sensitive to temperature changes compared to other battery types. These batteries are commonly used in applications where reliability is crucial, such as in electric vehicles and renewable energy systems. Although they have a lower energy density than some modern batteries, their robustness and ability to handle high charge and discharge cycles make them a viable option for specific uses.