KR-20260062365-A - UNIT CELL FOR SECONDARY AND SECONDARY BATTERY COMPRISING SAME

KR20260062365AKR 20260062365 AKR20260062365 AKR 20260062365AKR-20260062365-A

Abstract

The present invention relates to a secondary battery unit cell and aims to provide a secondary battery unit cell capable of maximizing the lifespan of the unit cell by mitigating local degradation of the electrode through modification of the geometric structure of the unit cell.

Inventors

이은주
나균일
손기현

Assignees

주식회사 엘지에너지솔루션

Dates

Publication Date: 20260507
Application Date: 20241029

Claims (8)

An anode portion including a surface extended in a first direction perpendicular to the vertical direction; A first separator layer laminated on one surface of the anode portion; A cathode portion laminated on the upper surface of the first separator; and It includes a second separator laminated on the upper surface of the above-mentioned cathode portion, and A void is formed in the above cathode, and A secondary battery unit cell comprising a first section including a center with respect to the first direction and a second section located on both sides of the first section, wherein the porosity of the first section is lower than the porosity of the second section.
In paragraph 1, A secondary battery unit cell in which the porosity of the first section is 2% to 5% lower than the porosity of the second section.
In paragraph 1, The above cathode part is, cathode current collector and, It includes a pair of cathode electrode layers each stacked on the upper and lower surfaces of the above-mentioned cathode current collector, and The above pair of cathode electrode layers each face the first separator and the second separator, and A secondary battery unit cell in which the above-mentioned void is formed in the above-mentioned pair of negative electrode layers.
In paragraph 3, When the direction perpendicular to the above vertical direction and the above first direction is called the second direction, A secondary battery unit cell in which the above pair of negative electrode layers are formed to be longer in the first direction than in the second direction.
In paragraph 4, The length of the first direction of the above-mentioned cathode current collector is formed to be longer than the length of the first direction of the above-mentioned pair of cathode electrode layers, and A secondary battery unit cell in which a negative lead tab is welded to the end of the above-mentioned negative current collector in the above-mentioned first direction.
In paragraph 4, The above secondary battery unit cell is a unit cell of a pouch-type secondary battery, and The length of the first direction of the above pair of cathode electrode layers is 100% to 500% of the length of the second direction, and A secondary battery unit cell in which the length of the first section is 40% to 80% of the first direction length of the pair of negative electrode layers.
In paragraph 1, A secondary battery unit cell in which the vertical thickness of the second section is formed to be 100% to 300% of the vertical thickness of the first section.
A secondary battery comprising an electrode assembly manufactured by stacking a plurality of secondary battery unit cells according to any one of claims 1 to 7.

Description

Unit cell for secondary battery and secondary battery comprising the same The present invention relates to a secondary battery unit cell and a secondary battery including the same, and more specifically, to a secondary battery unit cell capable of maximizing the lifespan of the unit cell by mitigating local degradation of the electrode by modifying the geometric structure of the unit cell. Rechargeable batteries are batteries capable of repeated use through the processes of discharging, which converts chemical energy into electrical energy, and charging, which converts electrical energy into chemical energy. Commonly known types include nickel-cadmium (Ni-Cd) batteries, nickel-hydrogen (Ni-MH) batteries, lithium-metal batteries, lithium-ion (Li-ion) batteries, and lithium-ion polymer batteries. Among these rechargeable batteries, lithium-ion batteries, which possess high energy density and voltage, long cycle life, and low self-discharge rates, have been commercialized and are widely used. The charging and discharging of a lithium secondary battery proceeds as the process of lithium ions being intercalated and deintercalated from the lithium metal oxide of the positive electrode to the negative electrode is repeated. A secondary battery can generally be manufactured by housing an electrode assembly, in which a cathode, a separator, and an anode are stacked and assembled, together with an electrolyte in a case such as a cylindrical can or a prismatic pouch. Specifically, a unit cell is manufactured by cutting, stacking, etc., the anode, separator, and cathode in a pre-designed manner. The manufactured unit cells can be stacked, folded, or rolled in a predetermined quantity to produce an electrode assembly. At this time, the electrodes in the secondary battery unit cell can have various geometric structures depending on the structure of the final secondary battery. As cycles (charges and discharges) are repeated, the electrodes of secondary batteries can gradually degrade. If the electrodes degrade unevenly in localized areas, the rate of degradation accelerates, which can reduce the overall lifespan of the secondary battery. Therefore, technology is needed for secondary battery unit cells capable of balanced electrode degradation during repeated charge-discharge cycles. FIG. 1 is a conceptual diagram showing a secondary battery unit cell according to one embodiment. Figure 2 is a cross-sectional view showing the cathode. Figure 3 is a plan view showing the cathode portion. Hereinafter, embodiments according to the present invention will be described in detail with reference to the attached drawings. In this process, the size or shape of components illustrated in the drawings may be exaggerated for clarity and convenience of explanation. Furthermore, terms specifically defined in consideration of the configuration and operation of the present invention may vary depending on the intent or convention of the user or operator. The definitions of such terms should be based on the content throughout this specification. In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "center," "top," "bottom," "left," "right," "vertical," "horizontal," "inner," "outer," "one side," and "other side" is based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship arranged when the product of the present invention is normally used. These terms are intended merely for the description and brief explanation of the invention and do not suggest or imply that the indicated device or element must have a specific orientation or be configured or operated in a specific orientation; therefore, they should not be understood as limiting the present invention. FIG. 1 is a conceptual diagram showing a secondary battery unit cell according to one embodiment of the present invention. FIG. 2 is a cross-sectional view showing a negative electrode (100). FIG. 3 is a plan view showing a negative electrode (100). Hereinafter, a secondary battery unit cell of the present invention will be described with reference to FIGS. 1 to 3. In the following description, the z-axis indicated in FIGS. 1 to 3 may be the up-down direction, the x-axis may be the first direction, and the y-axis may be the second direction. As illustrated in FIG. 1, the secondary battery unit cell of the present invention may include: a positive electrode (200) having a surface extended in a first direction perpendicular to the vertical direction; a first separator (310) stacked on the upper surface of the positive electrode (200); a negative electrode (100) stacked on the upper surface of the first separator (310); and a second separator (310) stacked on the upper surface of the negative electrode (100). In a secondary battery unit cell, the material of the negative electrode (100) may be prepared by mixing graphite or Si-based materials. Regar