Electrode active material electrode lithium-ion secondary battery method of making electrode active material and method of making lithium-ion secondary battery

A lithium-ion secondary battery comprising:

• a positive electrode including a first electrode active material containing Li, Mn, Ni, Co, and O atoms, and having a substantially halite type crystal structure;
• a negative electrode disposed so as to oppose said positive electrode;
• and
• an electrolyte disposed between said positive and negative electrode.

A method of making an electrode active material, said method comprising the steps of:

• preparing a first solution by dissolving an acid salt including an Mn atom, an acid salt including an Ni atom, and an acid salt including a Co atom into water or a solvent mainly composed of water;
• preparing a second solution by mixing said first solution with a solution including an NH4+ ion;
• forming a complex salt including Mn, Ni, and Co atoms by drying said second solution;
• and
• thermally reacting said complex salt with LiOH in an atmospheric air, so as to yield an electrode active material including Li, Mn, Ni, Co, and O atoms and having a substantially halite type crystal structure.