Copper foil for current collector of lithium secondary battery

A method of making an electrodeposited copper foil, having an area weight of the electrodeposited copper foil in the range of 26.7-329.4 g/m2, and a puncture strength Y, the puncture strength Y of the electrodeposited copper foil must lie in a range defined between a maximum value, Y1 (in N), and a minimum value, Y2 (in N), wherein the value Y1 is calculated by the following formula 1:

• Y1=−0.00007*X2+0.075*X−1.3373 formula 1:
• and the value Y2 is calculated by the following formula 2:
• Y2=0.00003*X2+0.0247*X−0.6454 formula 2:
• wherein X in each of formulas 1 and 2 represents the area weight of the electrodeposited copper foil (g/m2), and Y in each of formulas 1 and 2 represents the puncture strength of the electrodeposited copper foil (in N);
• comprising electrolytically depositing the copper foil from a copper-containing electrolyte solution, wherein the electrolyte solution further comprises 200-500 ppm of nickel.

A method of making a negative electrode for a high capacity rechargeable secondary battery, the method comprising:

• consolidating an electrode active material onto a copper foil having an area weight of the electrodeposited copper foil in the range of 26.7-329.4 g/m2, and a puncture strength Y, the puncture strength Y of the electrodeposited copper foil must lie in a range defined between a maximum value, Y1 (in N), and a minimum value, Y2 (in N), wherein the value Y1 is calculated by the following formula 1:
• Y1=−0.00007*X2+0.075*X−1.3373 formula 1:
• and the value Y2 is calculated by the following formula 2:
• Y2=0.00003*X2+0.0247*X−0.6454 formula 2:
• wherein X in each of formulas 1 and 2 represents the area weight of the electrodeposited copper foil (g/m2), and Y in each of formulas 1 and 2 represents the puncture strength of the electrodeposited copper foil (in N);
• the consolidating step comprising depositing the electrode active material onto the copper foil and applying elevated pressure to both the electrode active material and the copper foil to both compress the electrode active material and to consolidate the electrode active material with the copper foil.