Surface treatment method of copper foil, antioxidant copper foil, and cathode of lithium battery

A surface treatment method of a copper foil, comprising:

• providing a copper foil substrate;
• immersing the copper foil substrate in an antioxidant solution containing a chromic acid compound, an aminotetrazole compound, and a nitrogen-containing heterocyclic compound;
• and
• subjecting the copper foil substrate to be soaked or electroplated in the antioxidant solution for a predetermined time, such that an antioxidant layer is formed on a surface of the copper foil substrate, and an antioxidant copper foil is further formed;
• wherein the antioxidant copper foil satisfies the following characteristics:
• (a) the antioxidant layer has a chromium content of between 5 μg/m2 and 35 μg/m2 determined by X-ray fluorescence spectroscopy (XRF);
• wherein chromium elements in the antioxidant layer are derived from the chromic acid compound;
• (b) the antioxidant layer has a nitrogen content of between 0.1 wt % and 10 wt % determined by X-ray photoelectron spectroscopy (XPS);
• wherein nitrogen elements in the antioxidant layer are at least partially derived from the aminotetrazole compound and the nitrogen-containing heterocyclic compound;
• (c) the antioxidant copper foil has a carbon nitrogen signal (C—N signal) detected by headspace gas chromatography-mass spectrometry (headspace GC-MS);
• and
• (d) after baking the antioxidant copper foil at 250° C. for 10 minutes, a surface color difference ΔE of the antioxidant layer is not greater than 8 before and after the baking.