A nickel-metal hydride battery, abbreviated NiMH, is a type of rechargable battery similar to the nickel-cadmium cell. The NiMH battery use a hydrogen-absorbing alloy for the negative electrode instead of cadmium.
As in NiCd cells, the positive electrode is nickel oxyhydroxide (NiOOH). A NiMH battery can have two to three times the capacity of an equivalent size nickel-cadmium battery. NiMH batteries are classified as not dangerous, but as Special Provision A123 require, they must be packed to prevent short circuit by the effective insulation of exposed terminals and must also avoid accidental activation of the equipment in which they are installed.