Negative electrode for lithium secondary battery, method of producing the same and lithium secondary battery including the same
A negative electrode for a lithium secondary battery, a method of producing the negative electrode, and a lithium secondary battery including the negative electrode. Specifically, the negative electrode can reduce the initial irreversibility of the negative electrode because lithium metal ions are diffused into the negative electrode active material layer by pre-lithiation, and the negative electrode active material layer into which the lithium metal ions are diffused includes a plurality of line-shaped concave portions, so that when the lithium secondary battery is produced later, the concave portion keeps an electrolyte solution therein well to improve the impregnability of the electrolyte solution, thereby ultimately improving the electrochemical performance of the lithium secondary battery.
1 . A method of producing a negative electrode for a lithium secondary, the method comprising:
(a) applying a negative electrode active material layer on a surface of a negative electrode current collector;
(b) forming a lithium metal pattern on a surface of a polymer release film;
(c) disposing the lithium metal pattern on the negative electrode active material layer so that the lithium metal pattern formed on the polymer release film is in contact with the negative electrode active material layer to form a composite structure;
(d) pressing the result of (c) composite structure;
(e) removing the polymer release film from the result of (d) the lithium metal pattern of the pressed composite structure to produce a negative electrode loaded with the lithium metal pattern; and
(f) pre-lithiating the negative electrode loaded with the lithium metal pattern by impregnating the negative electrode loaded with the lithium metal pattern with a pre-lithiation solution,
wherein the lithium metal pattern is a line-and-space pattern, and
wherein the line-and-space pattern has a pattern height: width: interval ratio of 0.01 to 0.1:1 to 5:2 to 8.
2 . The method of claim 1 , wherein the pressing is roll pressing at a linear pressure of 1 kN/cm to 10 kN/cm.
3 . The method of claim 1 , wherein lithium in the lithium metal pattern is ionized through pre-lithiation and diffused into the negative electrode active material layer.
4 . The method of claim 3 , wherein, in the negative electrode, lithium metal is ionized and diffused into the negative electrode active material layer, thereby forming a line-shaped concave portion in a place from which the lithium metal pattern was prior to being ionized and diffused.
5 . The method of claim 1 , wherein the pre-lithiation solution comprises an ionizable lithium salt and an organic solvent.
6 . The method of claim 1 , wherein the removing step comprises peeling the polymer release film from the result of (d) the lithium metal pattern of the pressed composite structure.
7 . The method of claim 1 , wherein the polymer release film comprises a peelable polyethylene terephthalate (PET) film.