KR-102965283-B1 - ELECTRODE ASSEMBLY FOR RECHARGEABLE LITHIUM BATTERY, AND RECHARGEABLE LITHIUM BATTERY INCLUDING SAME

Abstract

The invention relates to a negative electrode for a lithium secondary battery and a lithium secondary battery including the same, wherein the negative electrode for the lithium secondary battery comprises a current collector, a first negative active material layer disposed on the current collector and comprising a first negative active material, and a second negative active material layer disposed on the first negative active material layer and comprising a second negative active material, wherein when XRD measurements are taken using CuKα rays, the ratio of the peak intensity of the (002) plane to the peak intensity of the (110) plane (I (002) /I (110) ) of the first negative active material layer and the second negative active material layer is each 150 or less.

Inventors

• 정준영
• 김성수
• 김정근

Assignees

• 삼성에스디아이 주식회사

Dates

Publication Date

20260513

Application Date

20210423

Claims (14)

1. Current collector; A first negative active material layer disposed on the current collector and comprising a first negative active material; and A second negative electrode active material layer disposed on the first negative electrode active material layer and comprising a second negative electrode active material, When XRD measurements are taken using CuKα rays, the first cathode active material layer and the second cathode active material layer have a peak intensity ratio of the (002) plane to the peak intensity of the (110) plane (I (002) /I (110) ) of 110 to 150, respectively. A negative electrode for a lithium secondary battery, wherein the first negative electrode active material and the second negative electrode active material are identical or different from each other and include a crystalline carbon-based active material and a Si-based negative electrode active material.
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3. In paragraph 1, The above peak intensity ratio (I (002) / I (110) ) is a value obtained after forming a first negative active material layer and a second negative active material layer by coating a composition for forming a first negative active material layer and a composition for forming a second negative active material layer onto a current collector to form a first layer and a second layer on top of the first layer, applying a magnetic field to the obtained product, and performing drying and rolling processes to form a first negative active material layer and a second negative active material layer, for a negative electrode for a lithium secondary battery.
4. In paragraph 1, The above peak intensity ratio (I (002) / I (110) ) is a value obtained after forming a first layer by coating a composition for forming a first negative active material layer on a current collector, forming a second layer by coating a composition for forming a second negative active material layer on the first layer, applying a magnetic field to the obtained product, and performing drying and rolling processes to form a first negative active material layer and a second negative active material layer, for a negative electrode for a lithium secondary battery.
5. In paragraph 1, The first negative electrode active material layer and the second negative electrode active material layer are orientation layers in which the first negative electrode active material and the second negative electrode active material are oriented on the current collector, for a negative electrode of a lithium secondary battery.
6. In paragraph 1, The first negative active material layer and the second negative active material layer are negative electrodes for a lithium secondary battery in which, when XRD measured using CuKα rays, the ratio of the peak intensity of the (002) plane to the peak intensity of the (110) plane (I (002) / I (110) ) is 90% or less of the ratio of the peak intensity of the non-oriented layer (I (002) / I (110) ) having the same composition and thickness as the first negative active material and the second negative active material layer.
7. In paragraph 1, A negative electrode for a lithium secondary battery, wherein the peel strength ratio of the first negative electrode active material layer to the peel strength of the second negative electrode active material layer is 70% to 90%.
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11. In paragraph 1, A negative electrode for a lithium secondary battery, wherein the thickness of the first negative electrode active material layer is 20㎛ to 125㎛ and the thickness of the second negative electrode active material layer is 20㎛ to 125㎛.
12. In paragraph 1, The above peak intensity ratio is of the peak appearing in I (002). Of the peak appearing in the integral area value / I (110) Negative electrode for a lithium secondary battery, which is the integral area value.
13. The cathode of any one of paragraphs 1, 3 through 7, 11 and 12; Anode; and electrolytes A lithium secondary battery including
14. In paragraph 1, The above Si-based negative electrode active material is a negative electrode for a lithium secondary battery, which is a Si-C composite.

Description

Negative electrode for a lithium secondary battery and a lithium secondary battery including the same The invention relates to a negative electrode for a lithium secondary battery and a lithium secondary battery including the same. Lithium secondary batteries, which are currently in the spotlight as power sources for small portable electronic devices, use an organic electrolyte and thus exhibit a discharge voltage more than twice as high as that of conventional batteries using an alkaline aqueous solution, and as a result, exhibit a high energy density. As the positive electrode active material for lithium secondary batteries, oxides composed of lithium and transition metals having a structure capable of lithium ion intercalation, such as LiCoO2 , LiMn2O4 , and LiNi1 -xCoxO2 ( 0 < x < 1 ), are mainly used. Various forms of carbon-based materials, including synthetic and natural graphite and hard carbon capable of lithium insertion/extraction, have been applied as cathode active materials; recently, research on non-carbon-based cathode active materials based on silicon or tin is being conducted to obtain higher capacity. FIG. 1 is a schematic diagram illustrating the orientation in one embodiment. FIG. 2 is a schematic diagram showing the structure of a lithium secondary battery according to one embodiment. Figure 3 is an SEM image showing the cross-section of the pre-rolled cathode prepared in Example 1 and Comparative Example 1. FIG. 4 is a graph showing the XRD peak intensities I (002) and I (110) measured using CuKα rays of the cathode precursor prepared after applying the cathode active material layer slurry during the process of Example 1 and Comparative Example 1, and the peak intensity ratio (I (002)/I (110)) obtained accordingly. FIG. 5 is a graph showing the XRD peak intensities I (002) and I (110) measured using CuKα rays of the cathode manufactured after applying and rolling the cathode active material layer slurry during the process of Example 1 and Comparative Example 1, and the peak intensity ratio (I (002)/I (110)) obtained accordingly. FIG. 6 is a graph comparing the average peak intensity ratio (I(002)/I(110)) of the cathode obtained after rolling according to the processes of Examples 1 to 3 and Comparative Examples 1 and 2. FIG. 7 is a graph showing the peel strength ratio (%) of the upper and lower parts of the cathode prepared according to Example 1, Comparative Example 1, and Comparative Example 2. FIG. 8 is a graph showing the ionic resistance (R ion ) of the cathode prepared according to Example 1 and Comparative Example 1. FIG. 9 is a graph showing the DC internal resistance (DC-IR) measured at different depths of discharge for a lithium secondary battery using a cathode prepared according to Example 1 and Comparative Example 1. FIG. 10 is a graph showing the room temperature cycle life characteristics of a lithium secondary battery using a cathode prepared according to Example 1 and Comparative Example 1 and Comparative Example 2. FIG. 11 is a graph showing the low-temperature cycle life characteristics of a lithium secondary battery using a cathode prepared according to Example 1 and Comparative Example 1 and Comparative Example 2. Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below. A negative electrode for a lithium secondary battery according to one embodiment comprises a current collector; a first negative active material layer disposed on the current collector and comprising a first negative active material; and a second negative active material layer disposed on the first negative active material layer and comprising a second negative active material, wherein when XRD measurements are taken using CuKα rays, the ratio of the peak intensity of the (002) plane to the peak intensity of the (110) plane (I (002) / I (110) ) of the first negative active material layer and the second negative active material layer is each 150 or less. In one embodiment, the peak intensity ratio (I (002) / I (110) ) may be 1 to 150. Generally, the peak intensity value refers to the height value of the peak or the integrated area value of the peak, and the peak intensity value according to one embodiment refers to the integrated area value of the peak. Furthermore, this value is maintained even when the lithium secondary battery containing such a negative electrode active material undergoes charging and discharging. The above peak intensity ratio may be a value obtained after forming the first cathode active material layer and the second cathode active material layer by coating the composition for forming the first cathode active material layer and the composition for forming the second cathode active material layer onto the current collector, i.e., simultaneously, to form the first layer and the se