Easily handleable electrolytic copper foil, electrode comprising the same, secondary battery comprising the same, and method for manufacturing the same
An easily handleable electrolytic copper foil securing a highly durable secondary battery, an electrode including same, a secondary battery including same, and a method of manufacturing same. The electrolytic copper foil including first and second surfaces includes a copper layer including a matte surface facing the first surface and a shiny surface facing the second surface, a first protective layer formed on the matte surface of the copper layer, and a second protective layer formed on the shiny surface of the copper layer. A coefficient of thermal expansion of the electrolyte copper foil measured using thermomechanical analyzer while heating the electrolytic copper foil from 30 to 190° C. at 5° C./min ranges from 16 to 22 μm/(m·° C.), tensile strength of the electrolytic copper foil measured after heat treatment at 190° C., ranges from 21 to 36 kgf/mm 2 , and weight deviation of the electrolytic copper foil is 5% or less.
1. An electrolytic copper foil, which includes a first surface and a second surface opposite the first surface, the electrolytic copper foil comprising:
a copper layer including a matte surface facing the first surface and a shiny surface facing the second surface;
a first protective layer on the matte surface of the copper layer; and
a second protective layer on the shiny surface of the copper layer,
wherein:
a coefficient of thermal expansion of the electrolytic copper foil, which is measured using a thermomechanical analyzer (TMA) while heating the electrolytic copper foil from 30° C. to 190° C. at a speed of 5° C./min, ranges from 16 to 22 μm/(m·° C.),
a tensile strength of the electrolytic copper foil, which is measured after a heat treatment at a temperature of 190° C. for 1 hour, ranges from 21 to 36 kgf/mm 2 ,
a weight deviation of the electrolytic copper foil is 5% or less,
a peak count (Pc) of each of the first and second surfaces of the electrolytic copper foil ranges from 3 to 92, and
each of the first and second surfaces has a surface roughness (R z ) of 3.5 μm or less.
2. The electrolytic copper foil of claim 1 , having an elongation of 3% or more at room temperature.
3. The electrolytic copper foil of claim 1 , wherein each of the first and second protective layers includes at least one of chromium (Cr), a silane compound, and a nitrogen compound.
4. The electrolytic copper foil of claim 1 , having a thickness of 4 to 30 μm.
5. The electrolytic copper foil of claim 1 , having a coefficient of thermal expansion of 17.3 to 22 μm/(m·° C.).
6. A secondary battery electrode comprising:
an electrolytic copper foil including a first surface and a second surface opposite the first surface; and
a first active material layer on the first surface of the electrolytic copper foil,
wherein the electrolytic copper foil comprises:
a copper layer including a matte surface facing the first surface and a shiny surface facing the second surface;
a first protective layer on the matte surface of the copper layer; and
a second protective layer on the shiny surface of the copper layer,
wherein a coefficient of thermal expansion of the electrolytic foil, which is measured using a TMA while heating the electrolytic copper foil from 30° C. to 190° C. at a speed of 5° C./min, ranges from 16 to 22 μm/(m·° C.),
wherein a tensile strength of the electrolytic copper foil, which is measured after a heat treatment at a temperature of 190° C. for 1 hour, ranges from 21 to 36 kgf/mm 2 ,
wherein a weight deviation of the electrolytic copper foil is 5% or less,
wherein a peak count (Pc) of each of the first and second surfaces of the electrolytic copper foil ranges from 3 to 92, and
wherein each of the first and second surfaces has a surface roughness (R z ) of 3.5 μm or less.
7. The secondary battery electrode of claim 6 , wherein the first active material layer includes at least one active material selected from the group consisting of carbon, a metal (Me) such as Si, Ge, Sn, Li, Zn, Mg, Cd, Ce, Ni, or Fe, an alloy containing the metal (Me), an oxide of the metal (MeO x ), and a composite of the metal (Me) and carbon.
8. The secondary battery electrode of claim 6 , wherein the first active material layer comprises Si.
9. The secondary battery electrode of claim 6 , further comprising a second active material layer on the second protective layer.
10. A secondary battery comprising:
a cathode;
an anode including a secondary battery electrode;
an electrolyte configured to provide an environment in which lithium ions may move between the cathode and the anode; and
a separator configured to electrically insulate the cathode from the anode,
wherein the secondary battery electrode comprises:
an electrolytic copper foil including a first surface and a second surface opposite the first surface; and
a first active material layer on the first surface of the electrolytic copper foil,
wherein the electrolytic copper foil comprises:
a copper layer including a matte surface facing the first surface and a shiny surface facing the second surface;
a first protective layer on the matte surface of the copper layer; and
a second protective layer on the shiny surface of the copper layer,
wherein a coefficient of thermal expansion of the electrolytic foil, which is measured using a TMA while heating the electrolytic copper foil from 30° C. to 190° C. at a speed of 5° C./min, ranges from 16 to 22 μm/(m·° C.),
wherein a tensile strength of the electrolytic copper foil, which is measured after a heat treatment at a temperature of 190° C. for 1 hour, ranges from 21 to 36 kgf/mm 2 ,
wherein a weight deviation of the electrolytic copper foil is 5% or less,
wherein a peak count (Pc) of each of the first and second surfaces of the electrolytic copper foil ranges from 3 to 92, and
wherein each of the first and second surfaces has a surface roughness (R z ) of 3.5 μm or less.