Nickel-metal hydride batteries (NiMH) are rechargeable energy storage devices that use nickel oxide hydroxide and a hydrogen-absorbing alloy as their electrodes. They are commonly found in various applications, including hybrid vehicles, portable electronics, and power tools, due to their ability to store more energy than traditional nickel-cadmium batteries. NiMH batteries offer several advantages, such as higher capacity, lower self-discharge rates, and reduced environmental impact compared to older battery technologies. However, they can be sensitive to temperature extremes and may require specific charging methods to ensure longevity and performance.