A nickel–zinc battery, abbreviated NiZn, is a type of rechargeable battery. It is similar to the nickel cadmium battery but with a higher voltage of 1.6 V. Large nickel–zinc battery systems have been known for over 100 years. Since 2000, development of a stabilized zinc electrode system has made this technology competitive with other commercially available rechargeable battery systems. Cells in "AA" and "AAA" sizes are available. Nickel–zinc batteries are not as toxic as nickel–cadmium batteries, and they are less of a fire risk than lithium–ion batteries. The energy density is higher than nickel–cadmium, but not quite as high as lithium–ion.