EP-4742305-A1 - AN APPARATUS AND A METHOD FOR ROLL-PRESSING AN ELECTRODE SHEET, AND AN ELECTRODE SHEET MANUFACTURED BY THE METHOD

EP4742305A1EP 4742305 A1EP4742305 A1EP 4742305A1EP-4742305-A1

Abstract

An apparatus for roll-pressing an electrode sheet is provided, wherein the electrode sheet has a coated portion in the middle along its width, extending in a longitudinal direction thereof and uncoated portions respectively positioned at both sides of the coated portion. The apparatus comprises: a stage on which the electrode sheet is to be placed; and a tab press roll configured to roll over one of the uncoated portions of the electrode sheet, for executing press work, wherein the tab press roll is configured, during the press work, to form a preset angle with respect to the stage, such that the tab press roll exerts less pressure at a side of the uncoated portion closer to the coated portion than the other side distant from the coated portion.

Inventors

CHOI, JIN HYEONG
HONG, JONG HYUK
LEE, GYU SUN

Assignees

LG Energy Solution, Ltd.

Dates

Publication Date: 20260513
Application Date: 20241108

Claims (15)

An apparatus for roll-pressing an electrode sheet, wherein the electrode sheet has a coated portion in the middle along its width, extending in a longitudinal direction thereof and uncoated portions respectively positioned at both sides of the coated portion, wherein the apparatus comprises: a stage on which the electrode sheet is to be placed; and a tab press roll configured to roll over one of the uncoated portions of the electrode sheet, for executing press work, wherein the tab press roll is configured, during the press work, to form a preset angle with respect to the stage, such that the tab press roll exerts less pressure at a side of the uncoated portion closer to the coated portion than the other side distant from the coated portion.
The apparatus of claim 1, wherein the tab press roll has a truncated cone shape.
The apparatus of claim 1, wherein the tab press roll has a cylindrical shape and is configured to, during the press work, be applied on the electrode sheet maintaining the preset angle with respect to the stage.
The apparatus of any one of the preceding claims, wherein a side of the tab press roll to be positioned closest to the coated portion during the press work is rounded or chamfered.
The apparatus of any one of the preceding claims, wherein the tab press roll has a concave-convex pattern on a surface thereof contacting the electrode sheet during the press work.
The apparatus of any one of the preceding claims, further comprising another tab press roll for tab-pressing the uncoated portion of the electrode sheet from an opposite side of the tab press roll, wherein the tab press roll and the another tab press roll are configured to engage each other having the electrode sheet interposed therebetween.
The apparatus of claim 6, wherein the another tab press roll is configured, during the press work, to form a preset angle with respect to the stage, such that the another tab press roll exerts less pressure at a side of the uncoated portion closer to the coated portion than the other side distant from the coated portion.
A method for roll-pressing an electrode sheet, wherein the electrode sheet has a coated portion in the middle along its width, extending in a longitudinal direction thereof and uncoated portions respectively positioned at both sides of the coated portion, wherein the method comprising: placing the electrode sheet on a stage; and executing press work by roll pressing one of the uncoated portions of the electrode sheet by a tab press roll, wherein during the press work, the tab press roll is applied on the electrode sheet forming a preset angle with respect to the stage, such that the tab press roll exerts less pressure at a side of the uncoated portion closer to the coated portion than the other side distant from the coated portion.
The method of claim 8, wherein the tab press roll has a truncated cone shape and, during the press work, the tab press roll is applied on the electrode sheet with its rotational axis parallel with the stage.
The method of claim 9, wherein the tab press roll has a cylindrical shape and, during the press work, the tab press roll is applied on the electrode sheet with its rotational axis maintaining the preset angle with respect to the stage.
The method of any one of the preceding claims, wherein, during the press work, the tab press roll imparts a concave-convex pattern on the uncoated portion of the electrode sheet.
The method of any one of the preceding claims, further comprising: executing press work by roll pressing the uncoated portion of the electrode sheet using another tab press roll from an opposite side of the tab press roll, wherein the tab press roll and the another tab press roll engage each other having the electrode sheet interposed therebetween, and wherein during the press work, the another tab press roll is applied on the electrode sheet forming a preset angle with respect to the stage, such that the another tab press roll exerts less pressure at a side of the uncoated portion closer to the coated portion than the other side distant from the coated portion.
An electrode sheet manufactured by the method of claims 8 to 12, comprising a coated portion in the middle along its width, extending in a longitudinal direction thereof, uncoated portions respectively positioned at both sides of the coated portion, and a tab formed of the uncoated portion, having been subject to the press work, wherein the tab is devoid of a line pattern extending in a width direction thereof and delimiting one side of the tab from the other side by a height.
The electrode sheet of claim 13, wherein the tab comprises a pattern formed on a surface thereof, and wherein the pattern comprises a depth continuously changing depending on a distance to the coated portion of the electrode sheet.
The electrode sheet of claim 14, wherein the depth of the pattern is shallower at a portion closer to the coated portion than at a portion farther from the coated portion.

Description

TECHNICAL FIELD The present invention relates to an apparatus and a method for roll-pressing an electrode sheet, as well as an electrode sheet manufactured by the same method. More particularly, the present invention relates to an apparatus for roll-pressing an electrode sheet capable of preventing the electrode sheet from being damaged during the roll-pressing process of the electrode sheet, or to be more specific, during the tab pressing process. The present invention also relates to a method for roll-pressing an electrode sheet, according to which the electrode sheet can be prevented from damage resulting from a pressure exerted during the roll-pressing process of the electrode sheet, or to be more specific, during the tab pressing process. Furthermore, the present invention also relates to an electrode sheet that is manufactured by the method for roll-pressing an electrode sheet, according to which the potential damage possibly resulting from a pressure exerted during the tab pressing process of the electrode sheet is avoided. BACKGROUND Secondary batteries, or often called rechargeable batteries, can be discharged by being used and then restored to their original state by charging. Secondary batteries have recently been widely used as an energy source of wireless devices, such as a personal digital devices, mobile telephone, or notebook computer. Moreover, the secondary battery has attracted attention as an energy source of an electric vehicle, a hybrid electric vehicle, and the like, which are regarded as a solution to the air pollution problem caused by traditional gasoline or diesel vehicles using fossil fuel. Due to the apparent advantages of the secondary battery over other traditional energy sources, the application of secondary battery continuously becomes wider and the consumer's demands for the secondary battery is also increasing. Among various secondary batteries, a lithium secondary battery is particularly widely used as an energy source for various electronic products because the lithium secondary battery shows a high energy density, a high operating voltage, as well as excellent storage and lifetime characteristics. As the field of application for secondary batteries expands, the demand for higher-capacity secondary batteries is increasing rapidly. As a method of increasing the capacity of a secondary battery, research is being conducted on a technique for increasing the loading amount of the electrode mixture layer. However, if the loading amount of the electrode mixture layer is increased, a volume increase of the electrode sheet is induced. In order to reduce the volume of the electrode sheet, a process of rolling the electrode sheet with a higher pressure is required. However, during the rolling process with a high pressure, a defect may occur at lateral sides of the electrode sheet. Accordingly, it would be advantageous to develop a technology capable of addressing the above technical problem, by preventing or reducing damages to an uncoated portion of an electrode sheet during the press work employing a tab press roll. SUMMARY OF THE INVENTION The present invention has been made in view of the above problem of the related art. It is one of the objects of the present invention to provide an apparatus and a method for roll-pressing an electrode sheet, which can prevent an electrode sheet from being damaged during the press work, particularly due to a pressure applied to the uncoated portions of the electrode sheet. One aspect of the present invention relates to an apparatus for roll-pressing an electrode sheet. The electrode sheet may have a coated portion in the middle along its width, extending in a longitudinal direction thereof and uncoated portions respectively positioned at both sides of the coated portion. The apparatus comprises a stage on which the electrode sheet is to be placed. The apparatus may further comprise a tab press roll configured to roll over one of the uncoated portions of the electrode sheet, for executing press work. Furthermore, the tab press roll may be configured, during the press work, to form a preset angle with respect to the stage, such that the tab press roll exerts less pressure at a side of the uncoated portion closer to the coated portion than the other side distant from the coated portion. Accordingly, the present invention enables to prevent or reduce a damage when a tab-pressing is performed on an uncoated portion of the electrode sheet by exerting less pressure at a portion of the uncoated portion adjacent to the coated portion. The electrode sheet to be subject to the roll-pressing by the apparatus may have a structure in which an electrode mixture layer is coated on one side or both sides of a current collector layer. To be specific, the electrode mixture layer may be a slurry containing an active material, a binder, and a solvent, wherein the active material is a component that undergo electrochemical reactions to store and release energy dur