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US-20260125268-A1 - PRE-DISPERSION SOLUTION, ELECTRODE COMPOSITION, ELECTRODE SLURRY, ELECTRODE, AND LITHIUM-ION SECONDARY BATTERY

US20260125268A1US 20260125268 A1US20260125268 A1US 20260125268A1US-20260125268-A1

Abstract

Disclosed is a pre-dispersion solution including single-walled carbon nanotubes (SWCNTs), in which with respect to 100 parts by weight of the entire single-walled carbon nanotubes, the content of single-walled carbon nanotubes having a length of more than 0 μm and less than 0.2 μm is more than 0 parts by weight and 1 part by weight or less, and the content of single-walled carbon nanotubes having a length of 10 μm or more and less than 100 μm is 15 parts by weight or more, and an electrode composition, an electrode slurry, an electrode, and a lithium ion secondary battery which include the same. Since the dispersibility of the pre-dispersion solutions is controlled, the pre-dispersion solution may contribute to the improvement in the phase stability of electrode compositions and/or electrode slurries and the stability, service life, safety, and the like of electrodes and/or lithium ion secondary batteries, in the future.

Inventors

  • Minjin Ko
  • Young Jae Kim
  • Chan Soo JUN
  • YoHan KWON
  • Jaewook Lee

Assignees

  • LG ENERGY SOLUTION, LTD.

Dates

Publication Date
20260507
Application Date
20240328
Priority Date
20230331

Claims (16)

  1. 1 . A pre-dispersion solution comprising single-walled carbon nanotubes, wherein a content of single-walled carbon nanotubes having a length of more than 0 μm and less than 0.2 μm is more than 0 parts by weight and 1 part by weight or less with respect to 100 parts by weight of a total amount of the single-walled carbon nanotubes, and a content of single-walled carbon nanotubes having a length of 10 μm or more and less than 100 μm is 15 parts by weight or more with respect to 100 parts by weight of the total amount of the single-walled carbon nanotubes.
  2. 2 . The pre-dispersion solution of claim 1 , further comprising single-walled carbon nanotubes having a length of 100 μm or more, wherein a content of single-walled carbon nanotubes having a length of 100 μm or more is 1 part by weight or less with respect to 100 parts by weight of the total amount of the single-walled carbon nanotubes.
  3. 3 . The pre-dispersion solution of claim 1 , further comprising single-walled carbon nanotubes having a length of 0.2 μm or more and less than 10 μm, wherein a content of the single-walled carbon nanotubes having a length of 0.2 μm or more and less than 10 μm is 30 parts by weight or more and 80 parts by weight or less with respect to 100 parts by weight of the total amount of the single-walled carbon nanotubes.
  4. 4 . The pre-dispersion solution of claim 1 , further comprising a dispersion medium, wherein the dispersion medium comprises at least one of water and an organic solvent.
  5. 5 . The pre-dispersion solution of claim 1 , further comprising a dispersant.
  6. 6 . An electrode composition comprising: an electrode active material; a conductive material; and a binder, wherein the conductive material comprises the pre-dispersion solution according to claim 1 , and the binder comprises a copolymer comprising a (meth)acrylamide (AM)-derived repeating unit.
  7. 7 . The electrode composition of claim 6 , wherein the electrode active material comprises one or more selected from the group consisting of a silicon-containing active material and a carbon-containing active material.
  8. 8 . The electrode composition of claim 7 , wherein the silicon-containing active material comprises one or more selected from the group consisting of SiOx, wherein x=0, SiOx, wherein 0<x<2, SiC, and a Si alloy.
  9. 9 . The electrode composition of claim 7 , wherein the electrode active material comprises the silicon-containing active material, the silicon-containing active material comprises one or more selected from the group consisting of SiOx, wherein x=0, and SiOx, wherein 0<x<2, and comprises 70 parts by weight or more of the SiOx, wherein (x=0), based on 100 parts by weight of the silicon-containing active material.
  10. 10 . The electrode composition of claim 7 , wherein the electrode active material comprises the carbon-containing active material, and the carbon-containing active material comprises at least one selected from the group consisting of artificial graphite, natural graphite, hard carbon, and soft carbon.
  11. 11 . The electrode composition of claim 7 , wherein the electrode active material comprises the silicon-containing active material and the carbon-containing active material, and a weight ratio between the silicon-containing active material and the carbon-containing active material is in a range of 2:98 to 30:70.
  12. 12 . The electrode composition of claim 6 , wherein the conductive material further comprises a planar conductive material.
  13. 13 . The electrode composition of claim 6 , wherein the binder comprises the (meth)acrylamide-derived repeating unit in an amount of 30 wt % or more and 80 wt % or less with respect to a total weight of the copolymer.
  14. 14 . An electrode slurry comprising the electrode composition according to claim 1 and a solvent.
  15. 15 . An electrode comprising: a current collector layer; and an electrode active material layer on one surface or both surfaces of the current collector layer, wherein the electrode active material layer comprises the electrode slurry according to claim 14 or a dried material thereof.
  16. 16 . A lithium ion secondary battery comprising: a first electrode; a second electrode; a separator between the first electrode and the second electrode; and an electrolyte, wherein the first electrode or the second electrode is the electrode according to claim 15 .

Description

TECHNICAL FIELD The present application relates to a pre-dispersion solution, an electrode composition, an electrode slurry, an electrode, and a lithium ion secondary battery. This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0042673 filed in the Korean Intellectual Property Office on Mar. 31, 2023, the entire contents of which are incorporated herein by reference. BACKGROUND ART Demands for the use of alternative energy or clean energy are increasing due to the rapid increase in the use of fossil fuels, and as a part of this trend, the most actively studied field is a field of electricity generation and electricity storage using an electrochemical reaction. Currently, representative examples of an electrochemical device using such electrochemical energy include a secondary battery, and the usage areas thereof are increasing more and more. Meanwhile, as technology development of and demand for mobile devices have increased, demands for secondary batteries have been rapidly increased. Accordingly, lithium secondary batteries having characteristics of high energy density and voltage, long cycle life, and low self-discharge rate have been commercialized and widely used. Accordingly, as an electrode for a high-capacity lithium secondary battery, studies have been actively conducted in order to prepare an electrode having a high energy density per unit volume. Generally, a secondary battery is composed of a positive electrode, a negative electrode, an electrolyte, and a separator, and in particular, the negative electrode includes a negative electrode active material, and silicon-containing particles with large charge and discharge capacities may be used as the negative electrode active material. In particular, recently, in response to the demand for a secondary battery having an electrode with a high energy, studies have been actively conducted on a method for increasing the capacity by together using a silicon-containing compound such as Si/C or SiOx (0<x<2), which has a 10-fold higher capacity than a graphite-based material, as a negative electrode active material. However, compared to existing graphite-based materials, silicon-containing compounds have a problem in that due to the generation of hydrogen gas in the repeated charging and discharging process, the volume expands to block the conductive path, thereby causing the battery characteristics to deteriorate. In order to solve the volume expansion caused by the above-described repeated charging and discharging process, studies have also been conducted on the composition of binders, and as a result, studies have been conducted on binder polymers having strong stress. However, these binder polymers alone have limitations in preventing an increase in electrode thickness due to contraction and expansion of a negative electrode active material and a deterioration in the performance of a lithium secondary battery derived therefrom. In addition, in order to secure the conductivity of the negative electrode, the secondary battery further includes a conductive material. Although carbon black and the like have been mainly used in the related art, single-walled carbon nanotubes (SWCNTs) with a thin and elongated shape have been used in order to improve the capacity of the secondary battery. However, when single-walled carbon nanotubes are used as a conductive material, the single-walled carbon nanotubes need to be used in the form of a dispersion solution of single-walled carbon nanotubes in order to uniformly arrange the single-walled carbon nanotubes in an active material layer. However, as the degree of dispersion of the dispersion solution increases, the density difference between a conductive material including the dispersion solution and an active material deepens, resulting in a migration in which the conductive material moves from a current collector to an upper layer, so that there is a problem in that the phase stability, conductivity, and the like of an electrode composition deteriorate. Therefore, in order to control the degree of dispersion of the dispersion solution, various methods have been discussed in terms of a dispersion medium, an active material, and a conductive material, and as one of these methods, a method of controlling dispersion by changing the particle size distribution of single-walled carbon nanotubes, which are conductive materials, has been discussed. DETAILED DESCRIPTION OF THE INVENTION Technical Problem The present inventors have found that excellent conductive network connectivity between active materials is maintained during charging and discharging of an electrode, and thus, the service life performance of a battery is excellent, and in order to control the dispersion stability and excellent coatability of single-walled carbon nanotubes used as conductive materials, the above problems can be solved by classifying the single-walled carbon nanotubes based on the length and limiting eac