KR-102963412-B1 - ELECTRODE ASSEMBLY AND LITHIUM SECONDARY BATTERY COMPRISING THE SAME

KR102963412B1KR 102963412 B1KR102963412 B1KR 102963412B1KR-102963412-B1

Abstract

The present invention relates to an electrode assembly comprising an electrode including an anode comprising an anode active material layer; a cathode comprising a cathode active material layer; a separator interposed between the anode and the cathode; and at least one fixing member for winding and fixing the electrode assembly in the full width direction, wherein the anode includes an anode sliding portion in which the thickness of the anode active material layer is reduced, and the at least one fixing member is arranged to overlap with a region corresponding to the anode sliding portion.

Inventors

김남훈
송재은
김정흡
김창호

Assignees

주식회사 엘지에너지솔루션

Dates

Publication Date: 20260512
Application Date: 20250625

Claims (12)

An electrode laminate comprising: an anode including an anode active material layer; a cathode including a cathode active material layer; and a separator interposed between the anode and the cathode, and An electrode assembly comprising at least one fixing member that fixes the outer surface of the electrode laminate by winding it in the full width direction, and The above anode includes an anode sliding portion in which the thickness of the anode active material layer is reduced, and The above at least one fixed member is arranged to overlap with an area corresponding to the anode sliding part, and The above electrode laminate is an electrode assembly having a total width of 50 mm to 200 mm and a total length of 200 mm to 1,000 mm.
In paragraph 1, The above-mentioned cathode is an electrode assembly comprising a cathode sliding portion in which the thickness of the cathode active material layer is reduced.
In paragraph 2, An electrode assembly in which the above-mentioned fixed member is arranged to overlap with at least a portion of the area corresponding to the above-mentioned cathode sliding part.
In paragraph 1, The above electrode laminate is an electrode assembly in which the ratio (L/W) of the total length (L) to the total width (W) is 3 or more.
In paragraph 1, The above electrode laminate is an electrode assembly in which the ratio of the total length (L) to the total width (W) is 3 to 7.
In paragraph 1, The electrode assembly comprises 2 to 10 fixing members, and An electrode assembly in which the above-mentioned fixed members are positioned symmetrically along the electric field direction.
In paragraph 6, An electrode assembly in which the above-mentioned fixed members are spaced apart at equal intervals.
In paragraph 1, The above-mentioned fixing member is an electrode assembly comprising a porous structure.
In paragraph 1, The above fixing member is an electrode assembly in which an adhesive layer is formed on one surface of a substrate having a porous structure.
In paragraph 1, The above fixed member is an electrode assembly having a width of 10 to 50 mm.
A lithium secondary battery comprising: an electrode assembly according to any one of claims 1 to 10; an electrolyte; and a battery case accommodating the electrode assembly and the electrolyte.
In Paragraph 11, The above battery case is a pouch-type battery case for a lithium secondary battery.

Description

Electrode assembly and lithium secondary battery comprising the same The present invention relates to an electrode assembly and a lithium secondary battery including the same, and more specifically, to an electrode assembly developed to suppress the occurrence of lithium plating (Li plating) in the electrode sliding portion and a lithium secondary battery including the same. With the advancement of technologies such as electric vehicles, energy storage systems (ESS), and portable electronic devices, the demand for lithium secondary batteries as an energy source is rapidly increasing. Lithium secondary batteries are classified into pouch type and can type depending on the material of the case accommodating the electrode assembly, and the electrode assembly may be classified into wound type (jelly-roll type), stacked type (stack type), stack and lamination type, or stack and folding type depending on the manufacturing method and form. Among these, the pouch-type secondary battery is manufactured by forming a cup portion by performing press processing on a flexible pouch film laminate, housing an electrode assembly in the cup portion, injecting an electrolyte, and then sealing the sealing portion; the can-type secondary battery is manufactured by housing an electrode assembly in a can made of metal material, injecting an electrolyte, and then sealing it by assembling a top cap on the top of the can. The electrode assembly has a structure comprising a positive electrode, a negative electrode, and a separator interposed between the positive and negative electrodes. The positive and negative electrodes are each manufactured by coating an electrode slurry onto a current collector to form an active material layer, followed by drying and rolling. When an electrode is manufactured by coating an electrode slurry, a sliding portion is formed at the end of the active material layer, in which the thickness of the active material layer gradually decreases. In the region where the electrode sliding portion is formed, the distance between the positive active material layer and the negative active material layer increases, and the adhesion to the separator decreases, making it prone to lithium plating (Li-plating). In addition, as lithium secondary batteries undergo repeated charging and discharging, the electrolyte is consumed, causing the amount of electrolyte to decrease. When the amount of electrolyte in the battery decreases, it cannot reach the electrode end, resulting in reduced electrolyte impregnation. Consequently, the mobility of lithium ions is reduced, which can lead to lithium plating (Li-plating). Meanwhile, as lithium secondary batteries are recently being applied as a power source for electric vehicles, lithium secondary batteries with a relatively long length relative to their width (hereinafter referred to as "long cells" for convenience) are being developed to accommodate battery space and location. While lithium secondary batteries with such long cell structures have the advantages of achieving high capacity and excellent space efficiency compared to conventional lithium secondary batteries, there is a problem in that as charging and discharging are repeated, the pressure decreases at the end of the electrode assembly near the electrode tab, causing the adhesion between the separator and the electrode to decrease, which further exacerbates lithium plating. Therefore, there is a need to develop an electrode assembly capable of preventing lithium plating in the electrode sliding portion and a lithium secondary battery including the same. FIG. 1 is a top view of an electrode assembly according to one embodiment of the present invention. FIG. 2 is a cross-sectional view of an electrode laminate according to one embodiment of the present invention. Figure 3 is a photograph showing the state of a lithium secondary battery after cycling, including an electrode assembly manufactured according to the example. Figure 4 is a photograph showing the state of a lithium secondary battery after cycling, including an electrode assembly manufactured by a comparative example. The present invention will be described in detail below. As a result of continuous research to develop a lithium secondary battery capable of achieving excellent performance and safety until the end of its lifespan, the inventors have discovered that by fixing the electrode stack with a fixing member during the formation of the electrode assembly and positioning the fixing member to overlap with the anode sliding portion area, not only can the interfacial adhesion between the electrode sliding portion and the separator be improved, but the pressure applied to the end portion of the electrode assembly can also be maintained relatively uniformly even during repeated charging and discharging cycles. Consequently, the degradation of battery performance can be minimized until the end of the battery's lifespan, and excellent safety can be achieved by suppre