Electrolytic copper foil, electrode comprising the same, secondary battery comprising the same, and method for manufacturing the same

Abstract

Disclosed are an electrolytic copper foil the fold and/or wrinkle of which can be avoided or minimized during a roll-to-roll process, a method for manufacturing the same, and an electrode and a secondary battery which are produced with such electrolytic copper foil so that high productivity can be guaranteed. An electrolytic copper foil of the invention has a longitudinal rising of 30 mm or less and a transverse rising of 25 mm or less, and the transverse rising is 8.5 times the longitudinal rising or less.

1 . An electrolytic copper foil having a first surface and a second surface opposite to the first surface, the electrolytic copper foil comprising:
 a first protective layer at the first surface;   a second protective layer at the second surface; and   a copper film between the first and second protective layers,   wherein the electrolytic copper foil has a longitudinal rising of 30 mm or less and a transverse rising of 25 mm or less,   the transverse rising is 8.5 times the longitudinal rising or less, and   the longitudinal rising and transverse rising are, when a center portion of the electrolytic copper foil is cut along a X-shaped cutting line of 5 cm×5 cm in a first direction which makes an angle of 35° to 55° with a longitudinal direction parallel with a transferring mark formed on the electrolytic copper foil and in a second direction perpendicular to the first direction so that a pair of first segments arranged side by side along the longitudinal direction and a pair of second segments arranged side by side along a transverse direction perpendicular to the longitudinal direction are formed, the greater of risings of the first segments in a direction the first or second surface is facing and the greater of risings of the second segments in a direction the first or second surface is facing, respectively.   
     
     
         2 . The electrolytic copper foil according to  claim 1 , wherein the first and second protective layers are respectively formed by depositing an anticorrosion material on the copper film, and
 a difference between deposition amount of the anticorrosion material of the first and second protective layers is 2.5 ppm/m2 or less.   
     
     
         3 . The electrolytic copper foil according to  claim 2 , wherein the anticorrosion material comprises at least one of chromate, benzotriazole, chromic oxide, and a silane compound. 
     
     
         4 . The electrolytic copper foil according to  claim 1 , wherein the electrolytic copper foil has a thickness of 4 to 35 μm. 
     
     
         5 . The electrolytic copper foil according to  claim 1 , wherein the first and second surfaces have a ten-point mean roughness RzJIS of 3.5 μm or less, and
 a ten-point mean roughness deviation of the first and second surfaces, which is calculated according to following formula, is 70% or less:
   formula:  RD=[|R 1− R 2|/( R 1, R 2)max]×100
 
 
 wherein R1 is the ten-point mean roughness of the first surface, R2 is the ten-point mean roughness of the second surface, RD is the ten-point mean roughness deviation of the first and second surfaces, |R1−R2| is a difference between the ten-point mean roughness of the first and second surfaces, and (R1, R2) max is the greater of the ten-point mean roughness of the first and second surfaces. 
 
     
     
         6 . An electrode for a secondary battery, the electrode comprising:
 the electrolytic copper foil according to  claim 1 ; and   an active material layer on the electrolytic copper foil,   wherein the active material layer comprises at least one active material selected from the group consisting of: carbon; a metal of Si, Ge, Sn, Li, Zn, Mg, Cd, Ce, Ni or Fe; an alloy including the metal; an oxide of the metal; and a complex of the metal and carbon.   
     
     
         7 . A secondary battery comprising:
 a cathode;   an anode;   an electrolyte for providing an environment enabling lithium ions to move between the cathode and the anode; and   a separator for electrically insulating the cathode from the anode,   wherein the anode comprises:   the electrolytic copper foil according to  claim 1 ; and   an active material layer on the electrolytic copper foil,   wherein the active material layer comprises at least one active material selected from the group consisting of: carbon; a metal of Si, Ge, Sn, Li, Zn, Mg, Cd, Ce, Ni or Fe; an alloy including the metal; an oxide of the metal; and a complex of the metal and carbon.   
     
     
         8 . A method for manufacturing an electrolytic copper foil, the method comprising:
 allowing a current to flow between an anode plate and a rotational cathode drum to form a copper film on the rotational cathode drum, the anode plate and rotational cathode drum spaced apart from each other in an electrolytic solution contained in an electrolytic bath; and   dipping the copper foil in an anticorrosion solution,   wherein the anode plate comprises first and second anode plates electrically insulated from each other,   the forming the copper film comprises forming a seed layer by allowing a current to flow between the first anode plate and the rotational cathode drum, and then growing the seed layer by allowing a current to flow between the second anode plate and the rotational cathode drum, and   a current density provided by the first anode plate is 1.5 times or more higher than a current density provided by the second anode plate.   
     
     
         9 . The method according to  claim 8 , wherein the anode plate further comprises a third anode plate between the first and second anode plates, and
 a current density provided by the third anode plate is lower than the current density provided by the first anode plate and higher than the current density provided by the second anode plate.   
     
     
         10 . The method according to  claim 8 , wherein the current density provided by the anode plate is 40 to 70 A/dm2. 
     
     
         11 . The method according to  claim 8 , further comprising taking the copper film out of the anticorrosion solution,
 wherein the copper film is guided by a guide roll disposed in the anticorrosion solution when the copper film is dipped in and taken out of the anticorrosion solution.   
     
     
         12 . The method according to  claim 11 , further comprising, after taking the copper film out of the anticorrosion solution, spraying an anticorrosion solution onto a surface of the copper film which was in contact with the guide roll during the dipping process. 
     
     
         13 . The method according to  claim 8 , wherein the electrolytic solution comprises 50 to 100 g/L of a copper ion, 50 to 150 g/L of sulfuric acid, 50 ppm or less of a chlorine ion and an organic additive. 
     
     
         14 . The method according to  claim 13 , wherein the organic additive is gelatin, hydroxyethyl cellulose (HEC), organic sulfide, organic nitride, a thiourea compound, or a mixture of two or more thereof. 
     
     
         15 . The method according to  claim 8 , wherein the electrolytic solution is supplied into the electrolytic bath at a flow rate of 40 to 46 m3/hour when the copper film is formed.