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US-12626909-B2 - Negative electrode active material, negative electrode including same, secondary battery including same, and method for manufacturing negative electrode active material

US12626909B2US 12626909 B2US12626909 B2US 12626909B2US-12626909-B2

Abstract

A negative electrode active material, a negative electrode including silicon-containing particles comprising SiO x , wherein 0<x<2, and a Li compound, and a carbon layer present on at least a part of a surface of the silicon-containing particles; and a layer comprising LiF present on at least a part of the silicon-containing particles having the carbon layer. During analysis by X-ray photoelectron spectroscopy (XPS), an atomic ratio (F/O ratio) of F relative to O is 0.45 or more and an atomic ratio (F/C ratio) of F relative to C is 0.5 or less.

Inventors

  • Ilgeun OH
  • Semi PARK
  • Sun Young Shin
  • Yong Ju Lee

Assignees

  • LG ENERGY SOLUTION, LTD.

Dates

Publication Date
20260512
Application Date
20220712
Priority Date
20210813

Claims (13)

  1. 1 . A negative electrode active material comprising: silicon-containing particles comprising SiO x , wherein 0<x<2, and a Li compound, and a carbon layer present on at least a part of a surface of the silicon-containing particles; and a layer comprising LiF present on at least a part of the silicon-containing particles having the carbon layer, wherein during analysis by X-ray photoelectron spectroscopy (XPS), an atomic ratio (F/O ratio) of F relative to O is 0.45 or more and an atomic ratio (F/C ratio) of F relative to C is 0.5 or less.
  2. 2 . The negative electrode active material of claim 1 , wherein when the negative electrode active material is analyzed by X-ray photoelectron spectroscopy (XPS), the atomic ratio (F/O ratio) of F relative to O is 0.48 or more and 2 or less.
  3. 3 . The negative electrode active material of claim 1 , wherein when the negative electrode active material is analyzed by X-ray photoelectron spectroscopy (XPS), the atomic ratio (F/C ratio) of F relative to C is more than 0 and 0.3 or less.
  4. 4 . The negative electrode active material of claim 1 , wherein the layer comprising LiF is present in an amount of 0.5 parts by weight to 5 parts by weight based on a total of 100 parts by weight of the negative electrode active material.
  5. 5 . The negative electrode active material of claim 1 , wherein a lithium compound is present between the silicon-containing particles and the layer comprising LiF.
  6. 6 . The negative electrode active material of claim 5 , wherein the lithium compound comprises one or more selected from the group consisting of Li 2 O, LiOH and Li 2 CO 3 .
  7. 7 . The negative electrode active material of claim 1 , wherein the layer comprising LiF is formed by a reaction of one or more lithium compounds selected from the group consisting of Li 2 O, LiOH and Li 2 CO 3 with HF.
  8. 8 . The negative electrode active material of claim 1 , wherein Li is present in an amount of 0.1 parts by weight to 40 parts by weight based on a total of 100 parts by weight of the negative electrode active material.
  9. 9 . The negative electrode active material of claim 1 , wherein the carbon layer is present in an amount of 0.1 parts by weight to 50 parts by weight based on a total of 100 parts by weight of the negative electrode active material.
  10. 10 . A method for preparing the negative electrode active material according to claim 1 , the method comprising: forming silicon-containing particles comprising SiO x , wherein 0<x<2, and a Li compound and having a carbon layer provided on at least a part of the surface thereof; and forming a layer comprising LiF on at least a part of the silicon-containing particles by reacting the silicon-containing particles with a HF solution.
  11. 11 . The method of claim 10 , wherein the forming of the layer comprising LiF on at least a part of the silicon-containing particles by reacting the silicon-containing particles with the HF solution comprises reacting the lithium compound provided on at least a part of the silicon-containing particles with the HF solution.
  12. 12 . A negative electrode comprising the negative electrode active material according to claim 1 .
  13. 13 . A secondary battery comprising the negative electrode according to claim 12 .

Description

TECHNICAL FIELD This application claims priority to and the benefit of Korean Patent Application Nos. 10-2021-0107525 and 10-2022-0008564 filed in the Korean Intellectual Property Office on Aug. 13, 2021 and Jan. 20, 2022, respectively, the entire contents of which are incorporated herein by reference. The present invention relates to a negative electrode active material, a negative electrode including the same, a secondary battery including the same and a method for preparing a negative electrode active material. BACKGROUND ART Recently, with the rapid spread of electronic devices using batteries such as mobile phones, notebook-sized computers, and electric vehicles, the demand for small and lightweight secondary batteries having relatively high capacity is rapidly increasing. In particular, lithium secondary batteries are lightweight and have high energy density, and thus have attracted attention as driving power sources for mobile devices. Accordingly, research and development efforts to improve the performance of lithium secondary batteries have been actively conducted. In general, a lithium secondary battery includes a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, an electrolyte solution, an organic solvent and the like. Further, for the positive electrode and the negative electrode, an active material layer each including a positive electrode active material and a negative electrode active material may be formed on a current collector. In general, lithium-containing metal oxides such as LiCoO2 and LiMn2O4 have been used as the positive electrode active material for the positive electrode, and lithium-free carbon-based active materials and silicon-based active materials have been used as the negative electrode active material for the negative electrode. Among the negative electrode active materials, the silicon-based active material is attracting attention because the silicon based active material has a high capacity and excellent high-speed charging characteristics compared to the carbon-based active material. However, the silicon-based active material has a disadvantage in that the initial efficiency is low because the degree of volume expansion/contraction due to charging/discharging is large and the irreversible capacity is large. Meanwhile, among the silicon-based active materials, a silicon-based oxide, specifically, a silicon-based oxide represented by SiOx (0<x<2) has an advantage in that the degree of volume expansion/contraction due to charging/discharging is low compared to other silicon-based active materials such as silicon (Si). However, the silicon-based oxide still has a disadvantage in that the initial efficiency is lowered depending on the presence of the irreversible capacity. In this regard, studies have been continuously conducted to reduce irreversible capacity and improve initial efficiency by doping or intercalating a metal such as Li, Al, and Mg into silicon-based oxides. However, in the case of a negative electrode slurry including a metal-doped silicon-based oxide as a negative electrode active material, there is a problem in that the metal oxide formed by doping the metal reacts with moisture to increase the pH of the negative electrode slurry and change the viscosity thereof, and accordingly, there is a problem in that the state of the prepared negative electrode becomes poor and the charge/discharge efficiency of the negative electrode is reduced. Accordingly, there is a need for the development of a negative electrode active material capable of improving the phase stability of a negative electrode slurry including a silicon-based oxide and improving the charge/discharge efficiency of a negative electrode prepared therefrom. Korean Patent No. 10-0794192 relates to a method for preparing a carbon-coated silicon-graphite composite negative electrode material for a lithium secondary battery and a method for preparing a secondary battery including the same, but has a limitation in solving the above-described problems. RELATED ART DOCUMENTS (Patent Document 1) Korean Patent No. 10-0794192 DETAILED DESCRIPTION OF THE INVENTION Technical Problem The present invention relates to a negative electrode active material, a negative electrode including the same, a secondary battery including the same and a method for preparing a negative electrode active material. Technical Solution An exemplary embodiment of the present invention provides a negative electrode active material including: silicon-based particles including SiOx (0<x<2) and a Li compound and having a carbon layer provided on at least a part of the surface thereof; and a layer including LiF provided on at least a part of the silicon-based particles, in which during analysis by X-ray photoelectron spectroscopy (XPS), an atomic ratio (F/O ratio) of F relative to O is 0.45 or more and an atomic ratio (F/C ratio) of F relative to C is 0.5 or less. An e