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US-12620571-B2 - Multi-layered electrode for battery and fabrication method thereof

US12620571B2US 12620571 B2US12620571 B2US 12620571B2US-12620571-B2

Abstract

A fabrication method of a multi-layered electrode for a battery includes (a) applying a binder solution including magnetic particles on a current collector, (b) applying a magnetic field to the current collector to which the binder solution is applied, and (c) applying an electrode slurry including an electrode active material on the binder solution.

Inventors

  • Min Hwan Kim
  • Dong Hoon Lee

Assignees

  • SK ON CO., LTD.

Dates

Publication Date
20260505
Application Date
20220519
Priority Date
20210928

Claims (11)

  1. 1 . A fabrication method of a multi-layered electrode for a battery, the method comprising steps: (a) applying a binder solution including magnetic particles and a conductive material on a current collector; (b) applying a magnetic field to the current collector to which the binder solution is applied; (c) following step (b), applying an electrode slurry including an electrode active material on the binder solution; and (d) performing drying after step (c), wherein the magnetic particles are directly coated on the conductive material, wherein the magnetic field applied in step (b) is a unidirectional magnetic field formed by a magnetic device positioned above and below the current collector.
  2. 2 . The method of claim 1 , wherein a total content of solid content in the binder solution is 0.5 to 50 wt %.
  3. 3 . The method of claim 1 , wherein a viscosity of the binder solution in step (a) is 500 cp or less.
  4. 4 . The method of claim 1 , wherein a weight ratio of the magnetic particles and a binder in the binder solution is 1:20 to 1:80.
  5. 5 . The method of claim 3 , wherein a content of the magnetic particles in the binder solution is 0.1 to 5 wt % based on a total weight of the binder solution.
  6. 6 . The method of claim 1 , wherein the magnetic particles include at least one selected from the group consisting of iron (Fe), nickel (Ni), and cobalt (Co).
  7. 7 . The method of claim 1 , wherein a binder in the binder solution is a water-soluble binder.
  8. 8 . The method of claim 1 , wherein step (b) is applying a magnetic field in a direction perpendicular to the current collector.
  9. 9 . The method of claim 1 , wherein a strength of the magnetic field is 100 to 5000 G, and a magnetic field application time is 1 second to 60 seconds.
  10. 10 . The method of claim 1 , wherein a viscosity of the binder solution before and after the application of the magnetic field satisfies Relational Expression 1 below, 1.2< A 2 /A 1 <5 [Relational Expression 1] wherein A 1 is a viscosity of the binder solution before the magnetic field is applied, and A 2 is a viscosity of the binder solution when the electrode slurry is applied after the magnetic field is applied.
  11. 11 . The method of claim 1 , wherein a viscosity of the binder solution during drying is 100 to 5000 cp.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to Korean Patent Application No. 10-2021-0127849 filed Sep. 28, 2021, the disclosure of which is hereby incorporated by reference in its entirety. BACKGROUND OF THE INVENTION Field of the Invention The following disclosure relates to a multi-layered electrode for a battery and a fabrication method thereof. Description of Related Art Recently, in line with growing demand for electronic devices such as mobile devices, the development of weight reduction and miniaturization of electrochemical batteries (secondary batteries) to increase portability of electronic devices has expanded. In addition to this trend, regulations on fuel efficiency and exhaust gas have been strengthened worldwide, so the growth of the electric vehicle (EV) market has accelerated and the development of a high-power, large-capacity battery for use in electric vehicles is required. In order to improve battery quality and performance, binders having high adhesion have been developed and a technology for lowering the content of binders has been developed, but there is a limit in types of binders having high adhesion and to lowering a binder content, and a serious problem may occur in that an electrode mixture layer is detached from the current collector during the process or charging/discharging process, and if the binder content is too low, a serious problem may occur in that an electrode composition layer is detached from a current collector during a notching process or the charging/discharging process. Therefore, a technology for efficiently distributing a binder inside an electrode has been developed. In this case, the binder content is formed to be higher at an interface of a current collector, thereby suppressing detachment, while lowering the binder content in the electrode mixture layer and a surface, to improve battery performance. To this end, a technology for forming a binder solution or electrode slurry having a high binder content in a lower layer and forming an electrode slurry having a low binder content in an upper layer, as a dual-layer, has been developed, but it may be difficult to maintain a uniform distribution of the binder in the lower layer, and a lower part liquid is pushed due to a high discharge pressure during coating of a supernatant liquid, which leads to a reduction in adhesion between the current collector-electrode mixture layer. Accordingly, it is necessary to develop a secondary battery with improved fast charging performance by solving the aforementioned problems and improving adhesion between the current collector-electrode mixture layer by optimizing the binder distribution in the electrode. SUMMARY OF THE INVENTION An embodiment of the present invention is directed to solving a problem arising as solid content in a lower binder solution are not maintained in a uniform distribution when electrode slurry is applied to an upper part of a binder solution during a process of forming an electrode active material layer by applying the binder solution and the electrode slurry onto a current collector, that is a problem of a degradation of adhesion between the current collector and the electrode active material layer. In one general aspect, a fabrication method of a multi-layered electrode for a battery includes: (a) applying a binder solution including magnetic particles on a current collector; (b) applying a magnetic field to the current collector to which the binder solution is applied; and (c) applying an electrode slurry including an electrode active material on the binder solution. A content of solid content in the binder solution may be 0.5 to 50 wt %. Viscosity of the binder solution in step (a) may be 500 cp or less. A weight ratio of the magnetic particles and the binder in the binder solution may be 1:20 to 1:80. A content of the magnetic particles in the binder solution may be 0.1 to 5 wt %. The magnetic particles may include at least one selected from the group consisting of iron (Fe), nickel (Ni), and cobalt (Co). The binder may be a water-soluble binder. Step (b) may be applying a magnetic field in a direction perpendicular to the current collector. The magnetic field applied in step (b) may be a unidirectional magnetic field formed by a magnetic device positioned above and below the current collector. A strength of the magnetic field may be 100 to 5000 G, and a magnetic field application time may be 1 second to 60 seconds. Viscosity of the binder solution before and after the application of the magnetic field may satisfy Relational Expression 1 below. 1.2<A2/A1<5  [Relational Expression 1] In Relational Expression 1, A1 is a viscosity of the binder solution before the magnetic field is applied, and A2 is a viscosity of the binder solution when the electrode slurry is applied after the magnetic field is applied. The method may further include (d) performing drying, after step (c), wherein the viscosity of the binder solution