The ZEBRA battery, based on the reaction sodium + nickel chloride double left right arrow sodium chloride + nickel, is well known for its high energy density of 118 W h/kg (cell) or 87 W h/kg (battery system including battery box and till peripheral equipment). The power density was increased in a first step by implementing a clover leaf-shaped ceramic electrolyte instead of the round tube electrolyte. A further improvement of the power density was achieved by doping of the positive nickel/nickel chloride electrode with iron, resulting in constant peak power of the battery system of 170 W/kg. The mechanism of the doping is described. The doping has no adverse effect on cycle life as a life test with presently 1100 nameplate cycles shows and this test is continuing.