Method for pre-lithiation and pre-sodium treatment of negative electrode, pre-lithiation and pre-sodium treatment negative electrode, and lithium secondary battery including pre-lithiation and pre-sodium treatment negative electrode

Disclosed is a method for pre-lithiation and pre-sodium treatment of a negative electrode, comprising the steps of: interposing a separator between a lithium ion supply metal sheet and a negative electrode to prepare a first simple battery; immersing the first simple battery in an electrolyte for pre-lithiation; carrying out initial electrochemical charging on the first simple battery immersed in the electrolyte for pre-lithiation so as to carry out pre-lithiation on the negative electrode; interposing a separator between the sodium ion supply metal sheet and the pre-lithiated negative electrode to prepare a second simple battery; immersing the second simple battery in an electrolyte for pre-sodium treatment; and performing secondary electrochemical charging on the second simple battery immersed in the electrolyte for pre-sodium modification so as to perform pre-sodium modification on the negative electrode. Also disclosed are a pre-lithiated and pre-sodium-modified negative electrode obtained by the method a