Development of high energy nickel-metal hydride cell

High energy nickel-metal hydride cell (71 Wh/kg and 230 Wh/l) has been developed by combining two kinds of electrodes: a pasted nickel hydroxide positive electrode using high density nickel hydroxide powder, and Zn(OH)/sub 2/ additive (2.8% weight), and a metal hydride negative electrode using a Zr(V/sub 0.1/Mn/sub 0.3/Co/sub 0.05/Ni/sub 0.55/)/sub 2.05/ alloy annealed at 950/spl deg/C for 12 hours and surface treated with an ultrasound solution.