Ni-MH rechargeable battery is also one type of alkaline storage battery, which is classified as a secondary battery. Ni-MH batteries use nickel hydroxide as the positive electrode, and hydrogen-absorbing alloys as the negative electrode, and an alkaline electrolyte. They are designated by IEC61951 as secondary cells and batteries containing alkaline or other non-acid electrolytes - “Portable sealed rechargeable single cells?- nickel-metal hydride.