In1901,Edison used NiO as cathode,iron as anode,develop the nickel iron battery.When nickel iron battery began to discover,NiO was used as an electrode,but because of the badly low temperature performance and the high manufacturing cost,it is gradually replaced by lithium battery now.During recent years, semiconductor-P of NiO begin to draw the attention of researcjers.After NiO adsorption gas or electric field,the number of nickel ion staying at its suface that change the conductivity and color of NiO.Above all,NiO can be used in the manufacture of resistance type semiconductor gas sensors and electroc