Method for preparing lithium-ion batteries

A method for preparing lithium-ion batteries, comprising:

• providing a positive electrode sheet, a negative electrode sheet, and a separator;
• winding or sheet-stacking the positive electrode sheet, the negative electrode sheet, and the separator, and then placing them into a case to form an initial cell, wherein the separator is positioned between the positive electrode sheet and the negative electrode sheet;
• injecting a first electrolyte into the initial cell, wherein the first electrolyte comprises:
• 0.5 wt % to 2 wt % vinylene carbonate, 5 wt % to 15 wt % lithium salt, and non-aqueous organic solvent (all by weight);
• performing a formation process on the initial cell to form an initial solid electrolyte interphase (SEI) film;
• and
• injecting a second electrolyte into the initial cell, wherein the second electrolyte comprises:
• 5 wt % to 20 wt % vinylene carbonate, 5 wt % to 15 wt % lithium salt, 0.005 wt % to 30 wt % infiltrant stabilizer, and non-aqueous organic solvent (all by weight);
• wherein the first electrolyte or the second electrolyte further comprises:
• at least one of 1,3-propane sultone or fluoroethylene carbonate, wherein an amount of 1,3-propane sultone is within a range of 0.1 wt % to 2 wt % by weight, and an amount of fluoroethylene carbonate is within a range of 0.1 wt % to 2 wt % by weight.