US-20260128310-A1 - METHOD FOR MANUFACTURING FREE-STANDING FILM FOR ANODE OF LITHIUM SECONDARY BATTERY AND FREE-STANDING FILM FOR ANODE OF LITHIUM SECONDARY BATTERY MANUFACTURED THROUGH THE SAME

Abstract

A method for manufacturing a free-standing film an anode, includes obtaining powders for forming the anode by mixing and grinding a composition for forming the anode including an anode active material, a conductive material, and a binder (S1), and forming an anode active material layer through a film forming process using the powders for forming the anode (S2). The binder includes a triblock copolymer including: a soft block that includes an aliphatic or cycloaliphatic diene monomer unit, and exhibits a rubbery phase at a room temperature, a first hard block that is linked to one end of the soft block, includes an ethylenically unsaturated monomer unit containing an aromatic ring, and exhibits a glass phase at a room temperature, and a second hard block that is linked to another end of the soft block, includes an ethylenically unsaturated monomer unit containing an aromatic ring, and exhibits the glass phase at the room temperature, and an average particle diameter (D 50 ) of the binder included in the powders for forming the anode is smaller than an average particle diameter (D 50 ) of the binder included in the composition for forming the anode.

Inventors

• Byung Yong LEE
• Ik Hyeon Choi
• Hyo Min Yoo
• Ju Young JANG

Assignees

• HYUNDAI MOTOR COMPANY
• KIA CORPORATION

Dates

Publication Date

20260507

Application Date

20250425

Priority Date

20241105

Claims (20)

1. 1 . A method for manufacturing a free-standing film for an anode, the method comprising: obtaining powders for forming the anode by mixing and grinding a composition for forming the anode including an anode active material, a conductive material, and a binder (S 1 ); and forming an anode active material layer through a film forming process using the powders for forming the anode (S 2 ), wherein the binder includes a triblock copolymer, the triblock copolymer including: a soft block that includes an aliphatic or cycloaliphatic diene monomer unit, and exhibits a rubbery phase at a room temperature, a first hard block that is linked to one end of the soft block, includes an ethylenically unsaturated monomer unit containing an aromatic ring, and exhibits a glass phase at a room temperature, and a second hard block that is linked to another end of the soft block, includes an ethylenically unsaturated monomer unit containing an aromatic ring, and exhibits the glass phase at the room temperature, and wherein an average particle diameter (D 50 ) of the binder included in the powders for forming the anode is smaller than an average particle diameter (D 50 ) of the binder included in the composition for forming the anode.
2. 2 . The method of claim 1 , wherein the binder included in the composition for forming the anode has a spherical shape, and an average sphericity ranges from 0.8 to 1.0.
3. 3 . The method of claim 1 , wherein the binder included in the composition for forming the anode includes a particle having an average particle diameter (D 50 ) ranging from 10 μm to 50 μm.
4. 4 . The method of claim 1 , wherein ‘S 1 ’ is performed through a grinder, and wherein the grinder has revolutions per minute (RPM) ranging from 15,000 rpm to 25,000 rpm.
5. 5 . The method of claim 1 , wherein the binder included in the powders for forming the anode includes a particle having an average particle diameter (D 50 ) ranging from 1 μm to 5 μm.
6. 6 . The method of claim 1 , wherein the film forming process is performed in a dry manner.
7. 7 . The method of claim 6 , wherein the film forming process includes calendering, and wherein the calendering is performed at a temperature equal to or higher than a first glass transition temperature and a second glass transition temperature corresponding to the first hard block and the second hard block, respectively.
8. 8 . The method of claim 1 , wherein each of the first hard block and the second hard block has a glass transition temperature ranging from 50° C. to 120° C., and wherein the soft block has a glass transition temperature ranging from −120° C. to −50° C.
9. 9 . The method of claim 1 , wherein an aliphatic or cycloaliphatic diene monomer for forming the aliphatic or cycloaliphatic diene monomer unit is at least one selected from the group consisting of a butadiene-based monomer, a pentadiene-based monomer, and a hexadiene-based monomer.
10. 10 . The method of claim 1 , wherein an ethylenically unsaturated monomer containing the aromatic ring for forming the ethylenically unsaturated monomer unit containing the aromatic ring is at least one selected from the group consisting of a styrene-based monomer and an aromatic (meth)acrylic monomer.
11. 11 . A free-standing film for an anode, the free-standing film comprising: a plurality of anode active materials, a plurality of conductive materials, and a binder, wherein the binder includes a tri block copolymer, the triblock copolymer including: a soft block that includes an aliphatic or cycloaliphatic diene monomer unit, and exhibits a rubbery phase at a room temperature, a first hard block that is linked to one end of the soft block, includes an ethylenically unsaturated monomer unit containing an aromatic ring, and exhibits a glass phase at a room temperature, and a second hard block that is linked to another end of the soft block, includes an ethylenically unsaturated monomer unit containing an aromatic ring, and exhibits the glass phase at the room temperature, wherein the binder has an intermittent column shape to link one anode active material among the plurality of anode active materials or one conductive material among the plurality of conductive materials, to another anode active materials among the plurality of anode active materials or another conductive material among the plurality of conductive materials, and wherein the binder has an average width of 50 nm perpendicular to a length direction.
12. 12 . The free-standing film of claim 11 , wherein a surface of the anode active material or a surface of the conductive material comprises a fused structure perpendicular to the length direction of the surface having an average width less than or equal to 30 nm, when an electron beam of 5.0 kV is irradiated to the free-standing film for the anode for at least one second to obtain a scanning electron microscope (SEM) image, and wherein the fused structure includes the triblock copolymer.
13. 13 . The free-standing film of claim 11 , wherein each of the first hard block and the second hard block has a glass transition temperature ranging from 50° C. to 120° C., and wherein the soft block has a glass transition temperature ranging from −120° C. to −50° C.
14. 14 . The free-standing film of claim 11 , wherein an aliphatic diene monomer for forming the aliphatic diene monomer unit is at least one selected from the group consisting of a butadiene-based monomer, a pentadiene-based monomer, and a hexadiene-based monomer.
15. 15 . The free-standing film of claim 11 , wherein an ethylenically unsaturated monomer containing the aromatic ring for forming the ethylenically unsaturated monomer unit containing the aromatic ring is at least one selected from the group consisting of a styrene-based monomer and an aromatic (meth)acrylic monomer.
16. 16 . An anode for a lithium secondary battery comprising: a current collector; and a free-standing film for the anode according to claim 11 , which is provided on the current collector.
17. 17 . A lithium secondary battery comprising: an anode for the lithium secondary battery according to claim 16 ; a cathode for the lithium secondary battery; and an electrolyte.
18. 18 . An anode for a lithium secondary battery comprising: a current collector; and a free-standing film for the anode according to claim 12 , which is provided on the current collector.
19. 19 . An anode for a lithium secondary battery comprising: a current collector; and a free-standing film for the anode according to claim 13 , which is provided on the current collector.
20. 20 . An anode for a lithium secondary battery comprising: a current collector; and a free-standing film for the anode according to claim 14 , which is provided on the current collector.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of priority to Korean Patent Application No. 10-2024-0155653 filed in the Korean Intellectual Property Office on Nov. 5, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD The present disclosure relates to a method for manufacturing a free-standing film for an anode of a lithium secondary battery by employing a triblock copolymer including a soft block and a hard block, and a free-standing film for an anode of a lithium secondary battery, which is manufactured through the same. BACKGROUND A lithium secondary battery has been extensively applied since the lithium secondary battery is first commercialized in 1990s, and continuously spotlighted as an energy storage device which has been mostly researched. The lithium secondary battery has requirements appropriate as an energy source of an electric vehicle due to a higher driving voltage, a higher energy density, a lower self-discharge rate, higher-rate performance, and longer cycle stability. Nevertheless, the lithium secondary battery applied to the electric vehicle faces three main issues of stability, operating time, and costs. The stability and the operating time may be resolved through the all-solid-state battery, but costs are a factor to interrupt widely applying the lithium secondary battery. Accordingly, many studies and researches have performed to save the costs of the lithium secondary battery. Reducing energy consumption necessary for manufacturing or increasing the thickness of an electrode is one of the most effective manners to reduce the manufacturing costs of the lithium secondary battery. According to a conventional technology for manufacturing an electrode, slurry, which is prepared by mixing an electrode active material, a polymer binder, and a conductive additive with water or an organic solvent, is casted to a current collector, and the result is dried and compressed to form an electrode. In this case, energy required to prepare the slurry and coat the current collector occupies 50% of energy consumed in the whole manufacturing process. Accordingly, studies and researches haven been performed with respect to a process for manufacturing the electrode in a dry manner without a solvent such that the manufacturing cost of the lithium secondary battery is reduced. Representatively, there has been, as a dry electrode manufacturing process, a technology for manufacturing a cathode of a lithium secondary battery in a drying manner using polytetrafluoroethylene (PTFE). PTFE may have the level of lowest unoccupied molecular orbitals (LUMO) to easily receive electrons. Accordingly, PTFE is electro-chemically unstable under a negative potential environment. Accordingly, an anode of the lithium secondary battery manufactured by employing PTFE as a binder exhibits an inferior cycle stability. In addition, when the anode is manufactured using the PTFE, a PTFE binder is decomposed during an initial charging operation, so the initial efficiency of the lithium secondary battery is lowered. Even though many studies and researches have been performed on a technology for manufacturing an electrode in a dry manner, the development of a technology for manufacturing an anode in a dry manner to manufacture the anode having an excellent physical property in moldability, electrochemical stability, or tensile force is still insufficient. Accordingly, studies and researches on the technology are required. SUMMARY The present disclosure has been made to solve the above-mentioned problems occurring in the prior art while advantages achieved by the prior art are maintained intact. An aspect of the present disclosure provides a free-standing film of a lithium secondary battery, capable of being easily formed, stabilized even at a negative potential, and strongly bound with an anode active material by applying a binder including a triblock copolymer including a hard block contributed to an excellent mechanical property and a soft block having flexibility, and being strongly bound to the anode active material and the conductive material by exhibiting excellent tensile force and forming a three dimensional network and a method for manufacturing the same, an anode for the lithium secondary battery including the free-standing film for the anode, and the lithium secondary battery. The technical problems to be solved by the present disclosure are not limited to the aforementioned problems, and any other technical problems not mentioned herein will be clearly understood from the following description by those skilled in the art to which the present disclosure pertains. According to an aspect of the present disclosure, a method for manufacturing a free-standing film for an anode, includes obtaining powders for forming the anode by mixing and grinding a composition for forming the anode including an anode active material, a conductive material, and a binder (S1), and f