Composite separator including porous coating layer made from slurry having improved dispersibility

Patent metadata

Field	Value
Publication number	US-11031656-B2
Application number	US-201815969345-A
Country	US
Kind code	B2
Filing date	May 2, 2018
Priority date	Nov 30, 2012
Publication date	Jun 8, 2021
Grant date	Jun 8, 2021

Abstract

The present disclosure relates to an invention directed to a composite separator having a porous coating layer, where the porous coating layer is prepared from a slurry by adjusting a particle diameter of an inorganic matter that is an ingredient of the slurry, so that a sinking rate of the inorganic particles may remarkably slow down and dispersibility may be dramatically improved, and as a result, the content of the inorganic particles may relatively increase and the inorganic particles may be uniformly distributed in the coating layer on a substrate, thereby preventing a reduction in battery performance.

First claim

What is claimed is:

1. A composite separator, comprising:
a porous substrate; and
a porous coating layer disposed on at least one surface of the porous substrate,
wherein the porous coating layer is prepared from a slurry, the slurry comprising:
inorganic particles;
a polymer; and
a solvent,
wherein the inorganic particles have an average diameter ranging from 0.9 μm to 15 μm,
wherein the polymer consists essentially of polyvinylidene fluoride-co-hexafluoropropylene,
wherein the solvent is any one selected from acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane and mixtures thereof,
wherein 10 to 50 parts by weight of the inorganic particles and 1 to 10 parts by weight of the polymer are present in the slurry based on 100 parts by weight of the solvent, and
wherein the slurry has a viscosity of which a lower bound is a value obtained from the following Equation 1 based on the average diameter of the inorganic particles and an upper bound is 10,000 cP:
η≥40 d 2   [Equation 1]

where η denotes the viscosity of the slurry in units of centipoise (cP), and d denotes the average diameter of inorganic particles in units of micrometers (μm),
wherein the porous substrate is a porous polymer film, and
wherein the composite separator having a thickness variation within ±0.5 μm.

2. The composite separator of claim 1 , wherein the porous coating layer has a structure that the inorganic particles are bonded to one another by the polymer while the inorganic particles are packed in contact with one another, where interstitial volumes between the inorganic particles are formed thereby, and such interstitial volumes between the inorganic particles form pores.

3. An electrochemical device, comprising:
a cathode;
an anode; and
the composite separator of claim 1 interposed between the cathode and the anode.

4. A composite separator, comprising:
a porous substrate; and
a porous coating layer disposed on at least one surface of the porous substrate,
wherein the porous coating layer is prepared from a slurry, the slurry comprising:
inorganic particles;
a polymer; and
a solvent,
wherein the inorganic particles are selected from the group consisting of an inorganic particle having a dielectric constant greater than or equal to 5, an inorganic particle having a lithium ion delivery capability, and a mixture thereof,
wherein the inorganic particles have an average diameter ranging from 0.9 μm to 15 μm
wherein the polymer consists essentially of polyvinylidene fluoride-co-hexafluoropropylene,
wherein 10 to 50 parts by weight of the inorganic particles and 1 to 10 parts by weight of the polymer are present in the slurry based on 100 parts by weight of the solvent, and
wherein the slurry has a viscosity ranging from 9 to 300 centipoise (cP),
wherein the porous substrate is a porous polymer film, and
wherein the composite separator having a thickness variation within ±0.5 μm.

5. The composite separator of claim 4 , wherein the porous coating layer has a structure that the inorganic particles are bonded to one another by the polymer while the inorganic particles are packed in contact with one another, where interstitial volumes between the inorganic particles are formed thereby, and such interstitial volumes between the inorganic particles form pores.

6. An electrochemical device, comprising:
a cathode;
an anode; and
the composite separator of claim 4 interposed between the cathode and the anode.

7. A composite separator, comprising:
a porous substrate; and
a porous coating layer disposed on at least one surface of the porous substrate,
wherein the porous coating layer is prepared from a slurry, the slurry comprising:
inorganic particles;
a polymer; and
a solvent,
wherein the inorganic particles have an average diameter ranging from 0.6 μm to 0.7 μm,
wherein the polymer consists essentially of polyvinylidene fluoride-co-hexafluoropropylene,
wherein the solvent is any one selected from acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane and mixtures thereof,
wherein 10 to 50 parts by weight of the inorganic particles and 1 to 10 parts by weight of the polymer are present in the slurry based on 100 parts by weight of the solvent, and
wherein the slurry has a viscosity of which a lower bound is a value obtained from the following Equation 1 based on the average diameter of the inorganic particles and an upper bound is 10,000 cP:
η≥40 d 2   [Equation 1]

where η denotes the viscosity of the slurry in units of centipoise (cP), and d denotes the average diameter of inorganic particles in units of micrometers (μm),
wherein the porous substrate is a porous polymer film, and
wherein the composite separator having a thickness variation within ±0.5 μm.

8. A composite separator, comprising:
a porous substrate; and
a porous coating layer disposed on at least one surface of the porous substrate,
wherein the porous coating layer is prepared from a slurry, the slurry comprising:
inorganic particles;
a polymer; and
a solvent,
wherein the inorganic particles are selected from the group consisting of an inorganic particle having a dielectric constant greater than or equal to 5, an inorganic particle having a lithium ion delivery capability, and a mixture thereof,
wherein the inorganic particles have an average diameter ranging from 0.6 μm to 0.7 μm
wherein the polymer consists essentially of polyvinylidene fluoride-co-hexafluoropropylene,
wherein 10 to 50 parts by weight of the inorganic particles and 1 to 10 parts by weight of the polymer are present in the slurry based on 100 parts by weight of the solvent, and
wherein the slurry has a viscosity ranging from 9 to 300 centipoise (cP),
wherein the porous substrate is a porous polymer film, and
wherein the composite separator having a thickness variation within ±0.5 μm.

Assignees

• Lg Chemical Ltd
• Toray Industries

Inventors

• Lee Joo-Sung
• Yoon Su-Jin
• Han Da-Kyung
• Ryu Bo-Kyung
• Kim Jong-Hun

Classifications

• H01M50/443

  Particulate material · CPC title

• H01M50/489

  Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties · CPC title

• H01M50/446 Primary

  Composite material consisting of a mixture of organic and inorganic materials · CPC title

• H01M4/622

  being polymers · CPC title

• H01M4/136

  Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy · CPC title