Nickel-cadmium (NiCd) batteries are rechargeable power sources 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. One notable characteristic of NiCd batteries is the "memory effect," which can reduce their capacity if they are not fully discharged before recharging. Despite their advantages, concerns about cadmium toxicity and environmental impact have led to a decline in their use in favor of other battery technologies, such as lithium-ion batteries.