Abstract: Recycling of lithium-ion batteries includes the steps of leaching a black mass including cathode and anode materials with a leaching agent, optionally including an oxidizing agent or reducing agent, to form an aqueous acidic leach solution of metal salts comprising metal salts and a plurality of impurity salts. The impurity salts are removed in various purification phases including treating with an oxygen-containing gas and optional electrodeposition and ion exchange steps, each at specified pH ranges. The amounts of the metal salts in the treated aqueous acidic leach solution are then adjusted to a desired ratio and coprecipitated to form a precursor cathode active material.