Preparation method of double-complexing-agent NCM622 type precursor multi-kettle series concentration process

The invention belongs to the field of NCM ternary precursor positive electrode materials, and particularly relates to a preparation method of a double-complexing-agent NCM622 type precursor multi-kettle series concentration process, which comprises the following steps: (1) preparing a nickel-cobalt-manganese sulfate solution with a certain concentration; (2) taking ammonia water and oxalic acid as complexing agents, taking sodium hydroxide as a precipitator, carrying out co-precipitation reaction on the complexing agents and the nickel-cobalt-manganese sulfate solution in a reaction kettle, and connecting a concentrator to concentrate and clear to obtain mixed slurry; and (3) detecting the solid content and the particle size in the reaction process, separating the slurry with the solid content reaching a certain value and the particle size not meeting the requirement into another reaction kettle, connecting another thickener for concentrating and clearing, discharging the slurry after the reaction in the reac