Method for predoping lithium, method of preparing lithium secondary battery comprising the same, and lithium secondary battery obtained therefrom

The present invention relates to a lithium predoping method, and particularly, to a lithium predoping method in which one or more unit cells are uniformly predoped with lithium in large quantities. According to an aspect of the present invention, provided is a lithium predoping method including: a step of preparing one or more unit cells, which include a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; a step of disposing the prepared one or more unit cells in a reaction tank and connecting electrodes having the same pole to each other; a step of adding electrolyte to the reaction tank; a step of disposing a lithium metal plate in the electrolyte and connecting the lithium metal plate to the negative electrode; and a step of doping the negative electrode. According to the present invention, an initial irreversible capacity of a negative electrode is decreased, and metal ions of a positive electrode are prevented from penetrating SEI on the surface of the negative electrode, thereby improving the capacity and cycle life of a battery.