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US-20260128290-A1 - Lithium Secondary Battery

US20260128290A1US 20260128290 A1US20260128290 A1US 20260128290A1US-20260128290-A1

Abstract

A lithium secondary battery may include an electrode assembly including a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and a separator disposed between the positive electrode and the negative electrode; an electrolyte; and a battery case accommodating the electrode assembly and the electrolyte, wherein the positive electrode active material includes a first lithium nickel-based oxide having at least one of a single particle type composed of one nodule and a pseudo-single particle type which is an aggregate of 30 or less nodules, in 50 wt % or more on the basis of the total weight of the positive electrode active material, and the negative electrode active material is composed of a Si/C composite and a carbon-based negative electrode active material.

Inventors

  • Seong Min LIM

Assignees

  • LG ENERGY SOLUTION, LTD.

Dates

Publication Date
20260507
Application Date
20231220
Priority Date
20221223

Claims (18)

  1. 1 . A lithium secondary battery comprising: an electrode assembly comprising a positive electrode comprising a positive electrode active material, a negative electrode comprising a negative electrode active material, and a separator disposed between the positive electrode and the negative electrode; an electrolyte; and a battery case accommodating the electrode assembly and the electrolyte, wherein the positive electrode active material comprises a first lithium nickel-based oxide having at least one of a single particle, the single particle having one nodule, and a pseudo-single particle, the pseudo-single particle being an aggregate of less than or equal to 30 nodules, in an amount of 50 wt % or more on the basis of a total weight of the positive electrode active material, and the negative electrode active material comprises a Si/C composite and a carbon-based negative electrode active material.
  2. 2 . The lithium secondary battery according to claim 1 , wherein the positive electrode active material further comprises a second lithium nickel-based oxide having a secondary particle, wherein the secondary particle is an aggregate of 40 or more primary particles.
  3. 3 . The lithium secondary battery according to claim 2 , wherein the first lithium nickel-based oxide and the second lithium nickel-based oxide are each independently represented by Formula 1: wherein, M 1 is Mn, Al, or a combination thereof, M 2 comprises one or more of W, Zr, Y, Ba, Ca, Ti, Mg, Ta, or Nb, 0≤x≤0.5, 0.8≤a<1, 0<b<0.2, 0<c<0.2, and 0≤d≤0.05.
  4. 4 . The lithium secondary battery according to claim 1 , wherein the first lithium nickel-based oxide has a D 50 from 3 μm to 10 μm.
  5. 5 . The lithium secondary battery according to claim 1 , wherein the first lithium nickel-based oxide has a D 90 of 10 μm or less, and a D 10 of 4 μm or less.
  6. 6 . The lithium secondary battery according to claim 1 , wherein the positive electrode has a loading density of 5.35 mAh/cm 2 or more.
  7. 7 . The lithium secondary battery according to claim 1 , wherein the positive electrode has a porosity from 22% to 25%.
  8. 8 . The lithium secondary battery according to claim 1 , wherein the positive electrode has a crack ratio of 30% or less.
  9. 9 . The lithium secondary battery according to claim 1 , wherein a weight ratio of Si/C composite: carbon-based negative electrode active material in the negative electrode active material is from 1:99 to 20:80.
  10. 10 . The lithium secondary battery according to claim 1 , wherein the Si/C composite has a grain size of 20 nm or less.
  11. 11 . The lithium secondary battery according to claim 1 , wherein the Si/C composite has a D 50 from 1 μm to 10 μm.
  12. 12 . The lithium secondary battery according to claim 1 , wherein the negative electrode has a loading density of 5.7 mAh/cm 2 or more.
  13. 13 . The lithium secondary battery according to claim 1 , wherein the negative electrode has a porosity from 24% to 30%.
  14. 14 . The lithium secondary battery according to claim 1 , wherein the negative electrode comprises a current collector, a first negative electrode active material layer formed on the current collector and a second negative electrode active material layer formed on the first negative electrode active material layer, wherein the first negative electrode active material layer and the second negative electrode active material layer each comprise a Si/C composites and a carbon-based negative electrode active materials as a negative electrode active materials, and the carbon-based negative electrode active materials included in the first negative electrode active material layer is different from the carbon-based negative electrode active material included in the second negative electrode active material layer.
  15. 15 . The lithium secondary battery according to claim 14 , wherein the carbon-based negative electrode active material in the first negative electrode active material layer comprises natural graphite, and the carbon-based negative electrode active material in the second negative electrode active material layer comprises artificial graphite.
  16. 16 . The lithium secondary battery according to claim 1 , wherein the electrode assembly is a jelly-roll type electrode assembly.
  17. 17 . The lithium secondary battery according to claim 1 , wherein the battery case is a cylindrical case.
  18. 18 . The lithium secondary battery according to claim 17 , wherein the lithium secondary battery has a form factor ratio of 0.4 or more.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application is a national stage entry under U.S.C. § 371 of International Application No. PCT/KR2023/021165 filed on Dec. 20, 2023, which claims priority to Korean Patent Application No. 10-2022-0183756 filed on Dec. 23, 2022, and Korean Patent Application No. 10-2023-0187328 filed on Dec. 20, 2023, the entire disclosure of each of which is incorporated by reference herein. TECHNICAL FIELD The present disclosure relates to a lithium secondary battery and more particularly, to a lithium secondary battery having excellent safety and electrochemical properties. BACKGROUND Recently, lithium secondary batteries have been in the spotlight as an energy source for electric vehicles. As the supply of electric vehicles spreads, the demand for lithium secondary batteries that can provide a longer driving range per charge and reduced quick charging time is increasing. Lithium secondary batteries are generally manufactured by a method including forming an electrode assembly by disposing a separator between a positive electrode including a positive electrode active material composed of a transition metal oxide containing lithium and a negative electrode including a negative electrode active material which is capable of storing lithium ions, inserting the electrode assembly in a battery case, injecting a non-aqueous electrolyte that serves as a medium for transferring lithium ions and sealing. The non-aqueous electrolyte is generally composed of a lithium salt, and an organic solvent which is capable of dissolving the lithium salt. Conventionally, as the negative electrode active material of lithium secondary batteries, carbon-based materials such as natural graphite and artificial graphite have been widely used. However, since the carbon-based negative electrode active materials have a small capacity and a slow reaction rate with lithium, secondary batteries using them have limitations in realizing high capacity and quick charging performance. Accordingly, attempts are being made to develop lithium secondary batteries using a silicon-based material such as silicon oxide (SiOx, 0<x<2), which has a large theoretical capacity, mixed with a carbon-based negative electrode active material. The silicon-based material has a high theoretical capacity compared to the carbon-based material and has a rapid reaction rate with lithium, and if applying the silicon-based material, there are advantages of improving capacity properties and quick charging performance. However, since the silicon-based material has very low electrical conductivity, its volume rapidly expands during the charging/discharging process, and as particles are broken or electrodes came off due to deterioration, battery performance rapidly decreases to be an obstacle to commercialization. SUMMARY Technical Problem The present disclosure is to solve the above-described defects and to provide a lithium secondary battery having excellent electrochemical performance by including 50 wt % or more of single particles/pseudo-single particles as a positive electrode active material and using a mixture of a SiC composite and a carbon-based negative electrode active material as a negative electrode active material. Technical Solution According to an aspect, the present disclosure provides a lithium secondary battery comprising: an electrode assembly comprising a positive electrode comprising a positive electrode active material, a negative electrode comprising a negative electrode active material, and a separator disposed between the positive electrode and the negative electrode; an electrolyte; and a battery case accommodating the electrode assembly and the electrolyte, wherein the positive electrode active material comprises a first lithium nickel-based oxide having at least one of a single particle type composed of one nodule and a pseudo-single particle type which is an aggregate of 30 or less nodules, in 50 wt % or more on the basis of the total weight of the positive electrode active material, and the negative electrode active material is composed of a Si/C composite and a carbon-based negative electrode active material. Meanwhile, the positive electrode active material may further comprise a second lithium nickel-based oxide having a secondary particle type which is an aggregate of 40 or more primary particles. The first lithium nickel-based oxide and the second lithium nickel-based oxide may be each independently represented by [Formula 1] below. In Formula 1, M1 is Mn, Al or a combination thereof, M2 comprises one or more selected from the group consisting of W, Zr, Y, Ba, Ca, Ti, Mg, Ta and Nb, 0≤x≤0.5, 0.8≤a<1, 0<b<0.2, 0<c<0.2, and 0≤d≤0.05. The first lithium nickel-based oxide may have D50 of 3 μm to 10 μm, D90 of 10 μm or less, and D10 of 4 μm or less. The positive electrode may have a loading density of 5.35 mAh/cm2 or more, a porosity of 22% to 25%, and a crack ratio of 30% or less. Meanwhile, the negative ele