Method of manufacturing an electrode comprising a dry electrode film and an electrode for an electrochemical device therefrom
Disclosed is a method for manufacturing a dry electrode. The method includes buffing the surface of a pre-electrode film formed in a sheet-like shape to remove the surface waviness in the manufacture of an electrode film, and then carrying out a calendering process, thereby ensuring the uniformity of the electrode film thickness and electrode active material density in the electrode film. In other words, it is possible to minimize a deviation in loading amount, porosity and thickness of the electrode depending on the location, and thus to provide improved overall electrochemical performance, including improved battery life characteristics.
1 . A method for manufacturing a dry electrode, comprising:
(S 10 ) compressing an electrode mixture powder for manufacturing a dry electrode film to be processed into a sheet-shaped pre-electrode film having a predetermined thickness;
(S 20 ) buffing one surface or both surfaces of the pre-electrode film transverse to the predetermined thickness of the pre-electrode film obtained from step (S 10 ) so as to reduce a surface waviness of the one surface or the both surfaces of the pre-electrode film; and
(S 30 ) calendering the pre-electrode film buffed from step (S 20 ) to obtain the dry electrode film.
2 . The method of claim 1 , wherein the dry electrode film obtained from step (S 30 ) shows a standard deviation in thickness of less than 2.5 μm.
3 . The method of claim 2 , wherein the dry electrode film obtained from step (S 30 ) shows a difference (|T Max −T Min |) between a maximum thickness (T Max ) and a minimum thickness (T Min ) of less than 5 μm.
4 . The method of claim 1 , wherein the electrode mixture powder comprises an electrode active material, a conductive material, and a binder resin, and the binder resin has been subjected to a micro-fibrilization process.
5 . The method of claim 4 , wherein the binder resin comprises polytetrafluoroethylene (PTFE).
6 . The method of claim 1 , wherein the compressing is carried out by using a powder compression molding device which comprises a roll pressing unit comprising two pressurizing rollers facing each other, and the electrode mixture powder is introduced between the pressurizing rollers.
7 . The method of claim 1 , wherein the calendering is carried out by using a calendering device which comprises a roll pressing unit comprising two pressurizing rollers facing each other, and the pre-electrode film is pressed by the roll pressing unit.
8 . The method of claim 7 , wherein the calendering device comprises two or more roll pressing units, and the pre-electrode film is calendered by being passed through the roll pressing units in multiple steps by the two or more roll pressing units.
9 . The method of claim 1 , wherein the buffing is carried out by allowing a buffing member to be in contact with one surface of the pre-electrode film so that the pre-electrode film is buffed from the one surface to a predetermined depth.
10 . The method of claim 9 , wherein a backup member is disposed at a position corresponding to the buffing member on the other surface of the pre-electrode film to pressurize and support the pre-electrode film in a direction of the buffing member.
11 . The method of claim 9 , wherein the buffing member is provided with a buffing pad comprising a buffing material on the surface thereof.
12 . The method of claim 1 , wherein the buffing is carried out for both surfaces of the pre-electrode film, and one surface of the pre-electrode film is subjected to buffing, and then the other surface thereof is subjected to the buffing sequentially.
13 . The method of claim 1 , wherein the dry electrode powder is obtained by:
(a) preparing a powdery mixture comprising an electrode active material, a conductive material, and a binder resin;
(b) kneading the powdery mixture at 70-200° C. to prepare mixture lumps; and
(c) pulverizing the mixture lumps to obtain an electrode powder.
14 . A method for manufacturing a dry electrode, comprising:
(S 10 ) compressing an electrode mixture powder for manufacturing a dry electrode film to be processed into a sheet-shaped pre-electrode film having a predetermined thickness;
(S 20 ) buffing one surface or both surfaces of the pre-electrode film transverse to the predetermined thickness of the pre-electrode film obtained from step (S 10 ) so as to reduce a surface waviness of the one surface or the both surfaces of the pre-electrode film; and
(S 30 ) calendering the pre-electrode film buffed from step (S 20 ) to obtain the dry electrode film,
wherein the buffing is carried out by allowing a buffing member to be in contact with one surface of the pre-electrode film so that the pre-electrode film is buffed from the one surface to a predetermined depth, and
wherein a backup member is disposed at a position corresponding to the buffing member on the other surface of the pre-electrode film to pressurize and support the pre-electrode film in a direction of the buffing member.