Nickel-Cadmium (NiCd) batteries are rechargeable energy storage devices that use nickel oxide hydroxide and cadmium as their electrodes. They are known for their ability to deliver high discharge rates and perform well in extreme temperatures. NiCd batteries are commonly used in portable electronics, power tools, and emergency lighting systems due to their durability and reliability. One notable characteristic of NiCd batteries is the "memory effect," which can reduce their capacity if they are not fully discharged before recharging. Despite this, they have a long cycle life and can be recharged hundreds of times. However, environmental concerns regarding cadmium, a toxic heavy metal, have led to a decline in their use in favor of other battery technologies like Lithium-Ion batteries.