EP-4228025-B1 - NEGATIVE ELECTRODE FOR RECHARGEABLE LITHIUM BATTERY AND RECHARGEABLE LITHIUM BATTERY INCLUDING SAME

Inventors

• AHN, Won-gi
• JEONG, MIN-YOUNG
• LEE, TAEIL
• BAE, JUHYE
• PARK, Gwangwon

Dates

Publication Date

20260506

Application Date

20230203

Claims (12)

1. A negative electrode (20) for a rechargeable lithium battery (100), comprising: a current collector (3); and a negative active material layer comprising a first active material layer (5), a second active material layer (7), and a third active material layer (9), wherein the first active material layer (5) is positioned to contact the current collector (3) and the second active material layer (7) is positioned between the first active material layer (5) and the third active material layer (9), the first active material layer (5) comprises a first active material of first crystalline carbon, the second active material layer (7) comprises a second active material which includes a silicon-based active material, a second crystalline carbon, and a third crystalline carbon, and the third active material layer (9) comprises a third active material of fourth crystalline carbon, wherein silicon is only included in the second active material layer.
2. The negative electrode for a rechargeable lithium battery of claim 1, wherein an amount of silicon is 0.6 wt% to 9 wt% based on the total, 100 wt% of the negative active material layer.
3. The negative electrode for a rechargeable lithium battery of claim 1 or 2, wherein a thickness ratio of the first active material layer (5), the second active material layer (7), and the third active material layer (9) is 1:1 to 49:1 to 49.
4. The negative electrode for a rechargeable lithium battery of claim 3, wherein a thickness ratio of the first active material layer (5), the second active material layer (7), and the third active material layer (9) is 1:1 to 1.5:1 to 1.5.
5. The negative electrode for a rechargeable lithium battery of any one of the preceding claims, wherein the first crystalline carbon and/or the second crystalline carbon is a natural graphite comprising secondary particles in which a plurality of primary particles are agglomerated and in which a coating layer comprising amorphous carbon is surrounding the secondary particles.
6. The negative electrode for a rechargeable lithium battery of claim 5, wherein the primary particles have an average particle diameter D50 of 5 µm to 15 µm and the secondary particles have an average particle diameter D50 of 8 µm to 24 µm, measured by laser diffraction.
7. The negative electrode for a rechargeable lithium battery of claim 5 or 6, wherein a peak intensity ratio I(002)/I(110) of the first crystalline carbon and/or the second crystalline carbon is 120 or less, when measured by XRD using a CuKa-ray.
8. The negative electrode for a rechargeable lithium battery of any one of claims 5 to 7, wherein amorphous carbon is positioned on the surface of the primary particles.
9. The negative electrode for a rechargeable lithium battery of any one of the preceding claims, wherein a mixing ratio of the second crystalline carbon and the third crystalline carbon is 1:1 to 1:9 by weight ratio.
10. The negative electrode for a rechargeable lithium battery of any one of the preceding claims, wherein the third crystalline carbon is artificial graphite.
11. The negative electrode for a rechargeable lithium battery of any one of the preceding claims, wherein the fourth crystalline carbon is artificial graphite, natural graphite, or a combination thereof.
12. A rechargeable lithium battery (100), comprising a negative electrode (20) of any one of the preceding claims; a positive electrode (10); and an electrolyte.

Description

BACKGROUND OF THE INVENTION (a) Field of the Invention It relates to a negative electrode for rechargeable lithium battery and a rechargeable lithium battery including the same. (b) Description of the Related Art Recently, the rapid spread of electronic devices such as mobile phones, laptop computers, and electric vehicles, using batteries require surprising increases in demands for rechargeable batteries with relatively high capacity and lighter weight. Particularly, a rechargeable lithium battery has recently drawn attention as a driving power source for portable devices, as it has lighter weight and high energy density. Accordingly, researches for improving performances of rechargeable lithium batteries are being actively undertaken. A rechargeable lithium battery includes a positive electrode and a negative electrode which may include an active material being capable of intercalating and deintercalating lithium ions, and an electrolyte, and generate electrical energy due to an oxidation and reduction reaction when lithium ions are intercalated and deintercalated into the positive electrode and the negative electrode. As for a positive active material of a rechargeable lithium battery, transition metal compounds such as lithium cobalt oxides, lithium nickel oxides, and lithium manganese oxide are mainly used. As the negative active material, a carbonaceous material such as a crystalline carbon material such as natural graphite or artificial graphite, or an amorphous carbonaceous material, or silicon-based material may be used. Recently, there have been attempts to thickly prepare a negative active material layer by using a carbonaceous material, especially, by mixing crystalline carbon with a silicon-carbon active material in order to improve a current density of the rechargeable lithium battery. For example, US 2021/0391570 A1 discloses a negative electrode for a lithium secondary battery. The negative electrode includes a current collector; a first negative electrode active material layer disposed on the current collector and includes a first graphite-based active material containing artificial graphite and natural graphite, and a first silicon-based active material; and a second negative electrode active material layer disposed on the first negative electrode active material layer and including a second graphite-based active material containing artificial graphite and natural graphite, and a second silicon-based active material. US 2020/0083536 A1 describes a negative active material for a rechargeable lithium battery based on natural graphite including secondary particles in which a plurality of primary particles are assembled; amorphous carbon on the surface of the primary particles; and a coating layer including amorphous carbon surrounding the secondary particles. US 2020/0176753 A1 relates to a negative electrode for a lithium secondary battery including a negative electrode current collector; a first negative electrode mixture layer present on at least one surface of the negative electrode current collector and including a first carbonaceous negative electrode active material, a first polymer binder and a first conductive material; a second negative electrode mixture layer present on a top surface of the first negative electrode mixture layer and including a silicon-based negative electrode active material, a second polymer binder and a second conductive material; and a third negative electrode mixture layer present on a top surface of the second negative electrode mixture layer and including a second carbonaceous negative electrode active material, a third polymer binder and a third conductive material. However, it causes to occur the deterioration and expansion of the negative electrode during charging and discharging, thereby fading the cycle-life characteristics and deteriorating the performances. SUMMARY OF THE INVENTION The invention is defined by the appended claims. One embodiment provides a negative electrode for a rechargeable lithium battery exhibiting excellent cycle-life characteristic and high capability characteristic. Another embodiment provides a rechargeable lithium battery including the negative electrode. In a first aspect the present invention provides a negative electrode for a rechargeable lithium battery including a current collector; and a negative active material layer including a first active material layer, a second active material layer, and a third active material layer, wherein the first active material layer is positioned to contact with the current collector and the second active material layer is positioned between the first active material layer and the third active material layer, the first active material layer includes a first active material of first crystalline carbon, the second active material layer includes a second active material which includes a silicon-based active material, a second crystalline carbon and a third crystalline carbon, and third activ