Electrolytic copper foil and electrode and lithium-ion cell comprising the same

Abstract

Provided are an electrolytic copper foil, an electrode, and a lithium-ion cell. The electrolytic copper foil comprising copper and chloride is analyzed by TOF-SIMS along its thickness direction to obtain a spectrum of a relative depth ratio as X-axis and a relative intensity of chloride versus copper as Y-axis. There is a chloride peak located between 20% and 80% of the relative depth ratio in the spectrum, and the chloride peak is characterized by a maximum relative intensity of chloride versus copper ranging from 0.77% to 5.13% and a full width at half maximum ranging from 2.31% to 5.78%. With above characteristics, the electrolytic copper foil has low density of copper particles, low degree of warpage, and good coating uniformity of the active material applied thereon, thereby optimizing the efficiency of a lithium-ion cell comprising the electrolytic copper foil.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]Pursuant to 35 U.S.C. § 119(a), this application claims the benefit of the priority to Taiwan Patent Application No. 109102500 filed on Jan. 22, 2020. The content of the prior application is incorporated herein by its entirety.BACKGROUND OF THE INVENTION1. Field of the Invention[0002]The invention relates to an electrolytic copper foil, particularly to an electrolytic copper foil for a lithium-ion cell. In addition, the invention also relates to an electrode comprising the electrolytic copper foil and a lithium-ion cell comprising the electrode.2. Description of the Prior Arts[0003]With the development of science and technology, there is a rising demand for energy, so the development of energy storage technologies has attracted much attention. A lithium-ion secondary cell (hereinafter referred to as the “lithium-ion cell”) is an electrochemical energy storage system. The lithium-ion cell plays an important role in our daily lives because i...

AI Technical Summary

Benefits of technology

[0006]To overcome the shortcomings, the objectives of the present invention are effectively mitigating or suppressing the degree of warpage of the electrolytic copper foil, improving the coating uniformity of the active material applied on the electrolytic copper foil, thereby optimizing the charge-discharge cycle life performance of the lithium-ion cell.

[0008]By controlling the values of the maximum relative intensity of chloride versus copper and the FWHM of the chloride peak located between 20% and 80% of the relative depth ratio in the TOF-SIMS spectrum of the electrolytic copper foil, the electrolytic copper foil has low density of copper particles, low degree of warpage, and good coating uniformity of the active material applied thereon, thereby optimizing the efficiency of a lithium-ion cell comprising the electrolytic copper foil.

[0010]Preferably, the electrolytic copper foil comprises copper particles on a surface thereof, a density of the copper particles with particle size ranging from 5 μm to 100 μm on the surface of the electrolytic copper foil is controlled at less than or equal to 5 particles per square meter (particles / m2). In other words, the particle size of the copper particles of the electrolytic copper foil may not exceed 100 μm, and the density of the copper particles may be controlled within a range less than or equal to 5 particles / m2. Controlling the density of the copper particles is helpful for improving the coating uniformity of the active material applied on the electrolytic copper foil. Further, a cell comprising the electrolytic copper foil may cope with problems generated by the localized discharge of an electrode, which is caused by copper particles.

[0012]Preferably, the FWHM of the chloride peak in the TOF-SIMS spectrum of the electrolytic copper foil may be further controlled within a range from 2.31% to 4% based on needs, thereby decreasing the degree of warpage of the electrolytic copper foil and avoiding cracking or wrinkling of the electrolytic copper foil after rolling.

[0013]Preferably, a ratio of a maximum height to a ten-point mean roughness (Ry / Rz) of a surface of the electrolytic copper foil may be less than or equal to 1.75. By controlling the surface morphology of the electrolytic copper foil, the coating uniformity of the active material applied on the electrolytic copper foil may be improved, thereby enhancing the charge-discharge cycle life performance of a lithium ion cell. More preferably, the ratio of the maximum height to the ten-point mean roughness (Ry / Rz) of the surface of the electrolytic copper foil may be 1.09 to 1.7.

Problems solved by technology

The slurry cannot be uniformly coated on the electrolytic copper foil if the warpage and the roughness of the electrolytic copper foil exceed an acceptable level, so the performance of the lithium-ion cell is degraded.

In addition, a warped electrolytic copper foil coated with the slurry is prone to be wrinkled after rolling, so the electrolytic copper foil is unable to be subsequently used to produce an electrode of a lithium-ion cell and is difficult to apply to the field of lithium-ion cells.

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