Separator and Lithium Secondary Battery Including the Same

Patent metadata

Field	Value
Publication number	US-2025112328-A1
Application number	US-202318833164-A
Country	US
Kind code	A1
Filing date	Jan 26, 2023
Priority date	Jan 26, 2022
Publication date	Apr 3, 2025
Grant date	—

Abstract

A separator includes: a polymer porous support; and a coating layer disposed on at least one surface of the polymer porous support and containing a binder polymer, wherein the binder polymer includes a polyvinylidene fluoride-based polymer and a cyanoethylated polymer, and the coating layer has a surface roughness (Ra) ranging from 300 nm to 500 nm. The separator includes a coating layer formed non-uniformly on the polymer porous support, and thus, can provide an effect of improving the workability of a battery assembling process. A method for manufacturing the separator, and a lithium secondary battery including the separator, are also provided.

First claim

1 . A separator, comprising:
a polymer porous support; and a coating layer including a binder polymer disposed on at least one surface of the polymer porous support, wherein the binder polymer comprises a polyvinylidene fluoride-based polymer and a cyanoethylated polymer, and the coating layer has a surface roughness (Ra) ranging from 300 nm to 500 nm.

2 . The separator of claim 1 , wherein the cyanoethylated polymer comprises one or more of cyanoethyl polyvinyl alcohol, cyanoethyl pullulan, cyanoethyl cellulose, cyanoethyl sucrose, cyanoethyl ester, cyanoethyl acetate, or cyanoethyl phosphate.

3 . The separator of claim 2 , wherein the cyanoethyl polyvinyl alcohol comprises a repeating unit represented by Chemical Formula 1 and a repeating unit represented by Chemical Formula 2 at a molar ratio ranging from 50:50-70:30:

4 . The separator of claim 1 , wherein the cyanoethylated polymer has a weight average molecular weight (Mw) ranging from 100,000 g/mol to 400,000 g/mol, a number average molecular weight (Mn) ranging from 50,000 g/mol to 200,000 g/mol, and a glass transition temperature (Tg) ranging from 0° C. to −100° C.

5 . The separator of claim 1 , wherein the polyvinylidene fluoride-based polymer comprises at least one of polyvinylidene fluoride, polyvinylidene fluoride-tetrafluoroethylene (PVDF-TFE), polyvinylidene fluoride-chlorotrifluoroethylene, polyvinylidene fluoride-trifluoroethylene, or polyvinylidene fluoride-trifluoroethylene-chlorofluoroethylene.

6 . The separator of claim 5 , wherein the polyvinylidene fluoride-based polymer comprises polyvinylidene fluoride-chlorotrifluoroethylene.

7 . The separator of claim 1 , wherein a weight ratio of the polyvinylidene fluoride-based polymer to the cyanoethylated polymer ranges from 85:15-99:1.

8 . The separator of claim 1 , wherein the coating layer is concentrated and formed locally on the at least one surface of the polymer porous support.

9 . The separator of claim 1 , wherein the surface roughness of the coating layer (Ra) ranges from 320 nm to 420 nm.

10 . A method for manufacturing a separator, comprising:
applying a slurry for coating containing a binder polymer to at least one surface of a polymer porous support; and dipping the polymer porous support coated with the slurry for coating in a composition including a non-solvent for the binder polymer so as to form a coating layer, wherein the binder polymer comprises a polyvinylidene fluoride-based polymer and a cyanoethylated polymer, and the coating layer has a surface roughness (Ra) ranging from 300 nm to 500 nm.

11 . The method of claim 10 , wherein the slurry for coating has a solid content ranging from 1 wt % to 7 wt %.

12 . A lithium secondary battery, comprising a positive electrode, a negative electrode, and the separator of claim 1 interposed between the positive electrode and the negative electrode.

Assignees

• Lg Chemical Ltd

Inventors

• Lee A-Young
• Lee Joo-Sung
• Jung Kil-An
• Kim Bong-Tae
• Lee Ji-Myeong

Classifications

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M50/449

  having a layered structure · CPC title

• H01M50/403

  Manufacturing processes of separators, membranes or diaphragms · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M2220/20

  Batteries in motive systems, e.g. vehicle, ship, plane · CPC title