Separator for lithium-ion battery and method for preparing the same

Patent metadata

Field	Value
Publication number	US-10141558-B2
Application number	US-201615017727-A
Country	US
Kind code	B2
Filing date	Feb 8, 2016
Priority date	Aug 28, 2013
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

A separator for a lithium-ion battery includes a substrate, a coating, and a middle layer formed between the substrate and the coating. The middle layer includes a part of the substrate and a part of the coating. The substrate contains a base polymer, a first polymer, and a first inorganic material. The coating contains a second polymer and a second inorganic material. The first polymer and the second polymer independently contain an acid radical in a side chain thereof. The first inorganic material is reactive with the first polymer via a first neutralization reaction, and the second inorganic material is reactive with the second polymer via a second neutralization reaction. A method for preparing a separator for a lithium-ion battery and a lithium-ion battery are also provided.

First claim

What is claimed is:

1. A separator for a lithium-ion battery, comprising:
a substrate comprising a base polymer, a first polymer, and a first inorganic material;
a coating comprising a second polymer and a second inorganic material; and
a middle layer formed between the substrate and the coating and comprising a part of the substrate and a part of the coating, wherein
the first polymer and the second polymer independently comprise an acid radical in a side chain thereof, the first inorganic material is reactive with the first polymer via a first neutralization reaction, and the second inorganic material is reactive with the second polymer via a second neutralization reaction.

2. The separator according to claim 1 , wherein the separator comprises two coatings and two middle layers, one of the two middle layers is formed between one of the two coatings and a first side surface of the substrate, and the other of the two middle layers is formed between the other of the two coatings and a second surface of the substrate.

3. The separator according to claim 1 , wherein the substrate has a thickness ranging from 10 μm to 40 μm, the coating has a thickness ranging from 0.1 μm to 1 μm, and the middle layer has a thickness ranging from 0.01 μm to 0.1 μm.

4. The separator according to claim 3 , wherein the substrate has a porosity ranging from 40% to 95%.

5. The separator according to claim 1 , wherein based on a total weight of the substrate, an amount of the first inorganic material is 1 wt % to 5 wt %, an amount of the first polymer is 2 wt % to 10 wt %, and an amount of the base polymer is 85 wt % to 97 wt %.

6. The separator according to claim 5 , wherein the first inorganic material has an average particle diameter ranging from 20 nm to 2 μm.

7. The separator according to claim 6 , wherein the coating further comprises a third inorganic material unreactive with the second polymer; and
based on a total weight of the coating, an amount of the second polymer is 30 wt % to 50 wt %, an amount of the second inorganic material is 6 wt % to 15 wt %, and an amount of the third inorganic material is 44 wt % to 55 wt %.

8. The separator according to claim 1 , wherein the first polymer and the second polymer are independently selected from a group consisting of ethylene-methacrylic acid copolymer, ethylene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid copolymer, ethylene propylene diene monomer rubber, sulfonated ethylene propylene diene monomer rubber, sulfonated butyl rubber, sulfonated butadiene styrene rubber, carboxylated polystyrene, sulfonated polystyrene, and combinations thereof.

9. The separator according to claim 8 , wherein the first inorganic material and the second inorganic material independently comprise at least one alkali compound of metals selected from the group consisting of sodium, potassium, lithium, calcium, magnesium, copper, manganese, zinc, plumbum, cobalt, aluminum and cesium; and
the third inorganic material is at least one selected from a group consisting of aluminum oxide, titanium oxide, calcium oxide, zinc oxide, copper oxide and manganese oxide.

10. A method for preparing a separator for a lithium-ion battery, comprising steps of:
providing a substrate and a coating respectively, wherein the substrate comprises a base polymer, a first polymer and a first inorganic material, and the coating comprises a second polymer and a second inorganic material; and
providing the coating onto the substrate by hot-pressing so as to form a middle layer comprising a part of the substrate and a part of the coating and formed between the substrate and the coating, wherein
the first polymer and the second polymer independently comprise an acid radical in a side chain thereof, the first inorganic material is reactive with the first polymer via a first neutralization reaction, and the second inorganic material is reactive with the second polymer via a second neutralization reaction.

11. The method according to claim 10 , wherein the hot-pressing is performed at a temperature of 100° C. to 200° C. for 0.5 minutes to 2 minutes.

12. The method according to claim 10 , wherein the coating further comprises a third inorganic material unreactive with the second polymer.

13. The method according to claim 12 , wherein the first polymer and the second polymer are independently selected from a group consisting of ethylene-methacrylic acid copolymer, ethylene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid copolymer, ethylene propylene diene monomer rubber, sulfonated ethylene propylene diene monomer rubber, sulfonated butyl rubber, sulfonated butadiene styrene rubber, carboxylated polystyrene, sulfonated polystyrene, and combinations thereof;
the first inorganic material and the second inorganic material independently comprise at least one alkali compound of metals selected from a group consisting of sodium, potassium, lithium, calcium, magnesium, copper, manganese, zinc, plumbum, cobalt, aluminum and cesium; and
the third inorganic material is at least one selected from a group consisting of aluminum oxide, titanium oxide, calcium oxide, zinc oxide, copper oxide and manganese oxide.

14. The method according to claim 12 , wherein based on a total weight of the substrate, an amount of the first inorganic material is 1 wt % to 5 wt %, an amount of the first polymer is 2 wt % to 10 wt %, and an amount of the base polymer is 85 wt % to 97 wt %; and
based on a total weight of the coating, an amount of the second polymer is 30 wt % to 50 wt %, an amount of the second inorganic material is 6 wt % to 15 wt %, and an amount of the third inorganic material is 44 wt % to 55 wt %.

15. The method according to claim 10 , wherein in the hot-pressing step, two coatings are provided and two middle layers are formed, one of the two middle layers is formed between one of the two coatings and a first side surface of the substrate, and the other of the two middle layers is formed between the other of the two coatings and a second surface of the substrate.

16. The method according to claim 10 , wherein the substrate has a thickness ranging from 10 μm to 40 μm, the coating has a thickness ranging from 0.1 μm to 1 μm, and the middle layer has a thickness ranging from 0.01 μm to 0.1 μm.

17. The method according to claim 16 , wherein the substrate has a porosity ranging from 40% to 95%.

18. The method according to claim 10 , wherein the first inorganic material has an average particle diameter ranging from 20 nm to 2 μm.

19. The method according to claim 10 , wherein the substrate is provided by melting the base polymer, the first polymer and the first inorganic material, and the coating is provided by melting the second polymer and the second inorganic material.

20. A lithium-ion battery comprising:
a shell; and
an electrode assembly and electrolyte sealed in the shell,
wherein the electrode assembly including a separator, comprising:
a substrate including a base polymer, a first polymer, and a first inorganic material;
a coating including a second polymer and a second inorganic material; and
a middle layer formed between the substrate and the coating and including a part of the substrate and a part of the coating, wherein the first polymer and the second polymer independently comprise an acid radical in a side chain thereof, the first inorganic material is reactive with the first polymer via a first neutralization reaction, and the second inorganic material is reactive with the

Assignees

• Byd Co Ltd

Inventors

• Chen Xiaofang
• Miao Weifeng

Classifications

• H01M10/0525 Primary

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

• H01M50/457

  comprising three or more layers · CPC title

• H01M50/451

  comprising layers of only organic material and layers containing inorganic material · CPC title

• H01M50/491

  Porosity · 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