Method for manufacturing ultrathin electrolytic copper foil

Abstract

The invention relates to a method for manufacturing a super-thin electrolytic copper foil. (1) An electrolyte contains 90-130g / L copper, 130-150g / L sulphuric acid. (2) The electrolyte is heated 55-66 DEG. C, 5-12 parts dithio-bis-propylene sulfonic acid sodium salt, 0.1-0.9 parts urinary sulfur, 0.9-2.2 parts 2-mercaptobenzothiazole and 20-50 parts polyethyleneglycol molecular weight 400 by weight ratio are added into the electrolyte in 1000 volume part per hour for entering an anode groove after being mixing well. (3) In an electric field, the current density is 65-75A / dm(2) for reacting and obtaining the super-thin electrolytic copper foil. The super-thin electrolytic copper foil crystal is tiny and uniform, difference of thickness uniform is less than 0.3 mum, Ra is less than 0.2 mum, Rz is not larger than 2.0 mum, tensile strength is in between 380-420 N / mm(2). A lithium battery with big capacity manufactured by the super-thin electrolytic copper foil has long cycle life of charge / discharge, and is not easy rupture during over charge.

Description

technical field [0001] The invention relates to a method for manufacturing an ultra-thin electrolytic copper foil, in particular to a method for manufacturing an ultra-thin electrolytic copper foil for a negative electrode current collector of a lithium battery. Background technique [0002] Electrolytic copper foil not only serves as the carrier of the negative electrode active material in the lithium battery, but also acts as the collector and transporter of the negative electrode electron flow. Therefore, the electrolytic copper foil current collector has a great influence on the electrochemical performance of the lithium battery. With the development of battery production technology and the improvement of the performance of ultra-thin electrolytic copper foil, lithium battery manufacturers usually use electrolytic copper foil to make the negative electrode current collector of lithium battery, especially the ultra-thin electrolytic copper foil for lithium battery negative...

AI Technical Summary

Problems solved by technology

The existing ultra-thin electrolytic copper foil for lithium battery negative electrode current collector has the following disadvantages: (1) the surface crystal structure of the electrolytic copper foil is magnified 1000 times with a scanning electron microscope to observe it, and it is found that the crystal particles are not dense enough on the surface of the electrolytic copper foil, and it is difficult to obtain The surface roughness Ra is less than 0.2 μm, and the height Rz of ten points of microscopic unevenness is not greater than 2.0 μm

However, when the copper foil is hard, the copper foil does not deform enough to adapt to the surface of the active material during the coating roll pressing, resulting in poor contact with the active material, reduced capacity, and shortened charge-discharge cycle life.

(3) The elongation rate of the existing ultra-thin electrolytic copper foil less than 8 μm is less than 2%, which is easy to cause cracks during coating roll pressing, resulting in reduced capacity and shortened charge-discharge cycle

(4) When the electrolytic copper foil is coated with negative electrode active materials such as carbon powder, the thickness uniformity is not uniform. If the deviation is large, it is easy to wrinkle on the coating machine, and the surface is uneven, resulting in large waste and increased cost.