Recent advancements in aluminum materials and aluminum electrochemistry open a current density compatibility domain in which aluminum anodes and nickel oxide cathodes can simultaneously discharge at high faradaic efficiency, The resultant overlapping compatibility region permits demonstration of an aluminum/nickel battery capable of unusually high specific power density and high specific energy density Al + 3NiOOH + NaOH + 3H(2)O --> NaAl(OH)(4) + 3Ni(OH)(2) The operational cell maintains a steady-state discharge voltage in excess of 2.3 V. Aluminum/nickel battery discharges are presented which yield a power density of 915 W/kg, and a specific energy density of up to 140 Wh/kg.