Active material reuse method using cathode scrap

A method of reusing a positive electrode active material, comprising:

• thermally treating a positive electrode scrap comprising a lithium composite transition metal oxide positive electrode active material layer, which includes an active material, disposed on a current collector in air at 300 to 650° C. for 1 hour or less, for thermal decomposition of a binder and a conductive material in the active material layer, wherein the positive electrode scrap is collected after punching a positive electrode plate in a positive electrode comprising the lithium composite transition metal oxide positive electrode active material layer on the current collector,
• separating the current collector from the active material layer,
• collecting the active material in the active material layer;
• and
• annealing the collected active material in air at 400 to 1000° C. with an addition of at least one of LiOH, Li2CO3, LiNO3 or Li2O.