nickelic oxide

noun Chemistry.
  1. a gray-black, water-insoluble powder, Ni2O3, which, at 600°C, decomposes to nickel oxide: used chiefly in storage batteries as an oxidizing agent.
Also called black nickel oxide, nickel sesquioxide.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018