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CN-115799463-B - Negative electrode active material and rechargeable lithium battery including the same

CN115799463BCN 115799463 BCN115799463 BCN 115799463BCN-115799463-B

Abstract

A negative active material for a rechargeable lithium battery and a rechargeable lithium battery are provided, the negative active material including a porous silicon-carbon composite including silicon, carbon, and magnesium silicate (MgSiO 3 ), and having a diffraction peak intensity ratio I MgSiO3(610) /I Si(111) of 0.001< I MgSiO3(610) /I Si(111) <0.01, the diffraction peak intensity ratio I MgSiO3(610) /I Si(111) being a ratio of a diffraction peak intensity I MgSiO3(610) of MgSiO 3 at 2θ=30 to 32 ° to a diffraction peak intensity I Si(111) of Si (111) detected at 2θ=27.5 to 29.5 ° in an X-ray diffraction analysis.

Inventors

  • LI ENZHU
  • JIN RONGXI
  • JIN ZAIYUAN
  • Luo Zaigao
  • Shen Kuilun

Assignees

  • 三星SDI株式会社

Dates

Publication Date
20260505
Application Date
20220905
Priority Date
20210909

Claims (19)

  1. 1. A negative active material for a rechargeable lithium battery, the negative active material comprising: A porous silicon-carbon composite comprising silicon, carbon and magnesium silicate, having a diffraction peak intensity ratio I Magnesium silicate (610) /I Silicon (Si) (111) of 0.001< I Magnesium silicate (610) /I Silicon (Si) (111) <0.01, the diffraction peak intensity ratio I Magnesium silicate (610) /I Silicon (Si) (111) being the ratio of the diffraction peak intensity I Magnesium silicate (610) of magnesium silicate at 2θ=30° to 32 ° to the diffraction peak intensity I Silicon (Si) (111) of silicon (111) detected at 2θ=27.5° to 29.5 ° in an X-ray diffraction analysis.
  2. 2. The anode active material for a rechargeable lithium battery according to claim 1, wherein the amount of magnesium silicate is 0.01wt% to 1.0wt%, based on the total 100wt% of the anode active material.
  3. 3. The anode active material for a rechargeable lithium battery according to claim 1, wherein the amount of magnesium silicate is 0.01wt% to 0.6wt%, based on the total 100wt% of the anode active material.
  4. 4. The negative active material for a rechargeable lithium battery according to claim 1, wherein the carbon comprises amorphous carbon.
  5. 5. The negative active material for a rechargeable lithium battery according to claim 4, wherein the amorphous carbon comprises soft carbon, hard carbon, or a combination thereof.
  6. 6. The anode active material for a rechargeable lithium battery according to claim 1, wherein the amount of carbon is 5 to 45wt% based on the total weight of the anode active material.
  7. 7. The negative active material for a rechargeable lithium battery according to claim 1, wherein the porous silicon-carbon composite includes pores, and carbon covers the outer walls of the pores, silicon, and magnesium silicate.
  8. 8. The anode active material for a rechargeable lithium battery according to claim 7, wherein the pores have an average size of 50nm or more.
  9. 9. The anode active material for a rechargeable lithium battery according to claim 8, wherein the pores have an average size of 50nm to 500 nm.
  10. 10. The negative active material for a rechargeable lithium battery according to claim 1, wherein the negative active material is prepared by: Performing a primary heat treatment on magnesium silicide to prepare a heated product; etching the heated product to produce porous silicon; mixing porous silicon with amorphous carbon precursor to prepare a mixture, and The mixture is subjected to a secondary heat treatment.
  11. 11. The anode active material for a rechargeable lithium battery according to claim 10, wherein the primary heat treatment is performed under an air atmosphere.
  12. 12. The anode active material for a rechargeable lithium battery according to claim 10, wherein the primary heat treatment is performed at 600 ℃ to 700 ℃ for 5 hours to 30 hours.
  13. 13. The negative electrode active material for a rechargeable lithium battery according to claim 10, wherein etching is performed using an acid.
  14. 14. The negative active material for a rechargeable lithium battery according to claim 13, wherein the acid is hydrochloric acid.
  15. 15. The anode active material for a rechargeable lithium battery according to claim 10, wherein a mixing ratio of the porous silicon and the amorphous carbon precursor is 95:5 to 55:45 by weight ratio.
  16. 16. The anode active material for a rechargeable lithium battery according to claim 10, wherein the secondary heat treatment is performed at 800 ℃ to 1200 ℃.
  17. 17. A rechargeable lithium battery, the rechargeable lithium battery comprising: a negative electrode comprising the negative electrode active material according to any one of claims 1 to 16; A positive electrode including a positive electrode active material, and A non-aqueous electrolyte.
  18. 18. The rechargeable lithium battery of claim 17, wherein the negative electrode comprises a negative electrode active material as the first negative electrode active material and crystalline carbon as the second negative electrode active material.
  19. 19. The rechargeable lithium battery according to claim 18, wherein a mixing ratio of the first negative electrode active material and the second negative electrode active material is 1:99 to 40:60 by weight ratio.

Description

Negative electrode active material and rechargeable lithium battery including the same Technical Field The present invention relates to a negative electrode active material and a rechargeable lithium battery including the same. Background The electric vehicle and ESS (energy storage system) market expansion requires a battery of high capacity and high efficiency, and studies have been made on using a silicon-based material as a negative electrode active material of the battery. The silicon-based anode active material has advantages of exhibiting high capacity and high efficiency, but has disadvantages associated with volume expansion during charge and discharge. To overcome these drawbacks, attempts have been made to combine materials with carbon substrates, silicon oxides or silicon alloys. The above information disclosed in this background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. Disclosure of Invention One embodiment provides a negative active material for a rechargeable lithium battery capable of improving initial efficiency and cycle life characteristics. Another embodiment provides a rechargeable lithium battery including a negative active material. One embodiment provides a negative active material for a rechargeable lithium battery, the negative active material including a porous silicon-carbon composite including silicon, carbon, and magnesium silicate (MgSiO 3) and pores, and having a diffraction peak intensity ratio I MgSiO3(610)/ISi(111) of 0.001< I MgSiO3(610)/ISi(111) <0.01, the diffraction peak intensity ratio I MgSiO3(610)/ISi(111) being a ratio of a diffraction peak intensity I MgSiO3(610) of MgSiO 3 at 2θ=30 ° to 32 ° to a diffraction peak intensity I Si(111) of Si (111) detected at 2θ=27.5 ° to 29.5 ° in an X-ray diffraction analysis. The amount of magnesium silicate may be about 0.01wt% to about 1.0wt% or about 0.01wt% to about 0.6wt% based on the total 100wt% of the anode active material. The carbon may be amorphous carbon, and the amorphous carbon may be soft carbon, hard carbon, or a combination thereof. The amount of carbon may be about 5wt% to about 45wt% based on the total weight of the anode active material. The silicon-carbon composite may include pores and carbon may cover the outer walls of the pores, silicon, and magnesium silicate. The pores may have an average size of about 50nm or greater or from about 50nm to about 500 nm. The anode active material may be prepared by performing a primary heat treatment on magnesium silicide to prepare a heated product, etching the heated product to prepare porous silicon, mixing porous silicon with an amorphous carbon precursor to prepare a mixture, and performing a secondary heat treatment on the mixture. The primary heat treatment may be performed under an air atmosphere. The primary heat treatment may be performed at about 600 ℃ to about 700 ℃ for about 5 hours to about 30 hours. Etching may be performed using an acid. The acid may be hydrochloric acid. The mixing ratio of porous silicon and amorphous carbon precursor may be about 95:5 to about 55:45 by weight. The secondary heat treatment may be performed at about 800 ℃ to about 1200 ℃. Another embodiment provides a rechargeable lithium battery including a negative electrode including a negative active material, a positive electrode including a positive active material, and a non-aqueous electrolyte. The negative electrode may further include a negative electrode active material as a first negative electrode active material and crystalline carbon as a second negative electrode active material. The mixing ratio of the first anode active material and the second anode active material may be about 1:99 to about 40:60 by weight ratio. Other embodiments are included in the following detailed description. The negative active material for a rechargeable lithium battery according to one embodiment may exhibit excellent initial efficiency and cycle life characteristics. Drawings Fig. 1 is a schematic view showing the structure of a rechargeable lithium battery according to an embodiment. Detailed Description Hereinafter, embodiments are described in detail. However, these embodiments are merely examples, and the invention is not limited thereto, but is defined by the scope of the claims. The negative active material for a rechargeable lithium battery includes a porous silicon-carbon composite including silicon, carbon, and magnesium silicate (MgSiO 3). The anode active material may have a diffraction peak intensity ratio I MgSiO3(610)/ISi(111) of 0.001< I MgSiO3(610)/ISi(111) <0.01, which diffraction peak intensity ratio I MgSiO3(610)/ISi(111) is a ratio of diffraction peak intensity I MgSiO3(610) of MgSiO 3 at 2θ=30° to 32 ° to diffraction peak intensity I Si(111) of Si (111) detected at 2θ=27.5° to 2