Composite separator and preparation method therefor, and lithium-ion battery

Patent metadata

Field	Value
Publication number	US-2018034029-A1
Application number	US-201715726385-A
Country	US
Kind code	A1
Filing date	Oct 6, 2017
Priority date	Apr 9, 2015
Publication date	Feb 1, 2018
Grant date	—

Abstract

A composite separator is disclosed. The composite separator includes a base membrane, and a composite gel composited with the base membrane. The composite gel includes a gel polymer and a nano-barium sulfate dispersed in the gel polymer. A surface of the nano-barium sulfate is modified with lithium carboxylate group. A method for preparing the composite separator and a lithium-ion battery are also provided.

First claim

What is claimed is:

1 . A composite separator, comprising:
a base membrane; and a composite gel composited with the base membrane, the composite gel comprising a gel polymer and a nano-barium sulfate dispersed in the gel polymer, and a surface of the nano-barium sulfate being modified with a lithium carboxylate group.

2 . The composite separator of claim 1 , wherein the lithium carboxylate group comprises at least eight carbon atoms.

3 . The composite separator of claim 1 , wherein the nano-barium sulfate comprises a plurality of barium sulfate particles, and a plurality of mesopores are formed inside each barium sulfate particle of the nano-barium sulfate.

4 . The composite separator of claim 1 , wherein the composite gel forms a layer structure on a surface of the base membrane.

5 . The composite separator of claim 4 , wherein a thickness of the layer structure is in a range from about 2 μm to about 10 μm.

6 . The composite separator of claim 1 , wherein a particle size of the nano-barium sulfate is in a range from about 30 nm to about 500 nm.

7 . The composite separator of claim 1 , wherein the gel polymer is selected from the group consisting of polymethyl methacrylate, copolymer of vinylidene fluoride and hexafluoropropylene, polyacrylonitrile, and polyoxyethylene, and combinations thereof.

8 . The composite separator of claim 1 , wherein a mass ratio between the nano-barium sulfate and the gel polymer is in a range from about 2:100 to about 30:100.

9 . A method for preparing a composite separator, comprising:
adding lithium carboxylate into a first organic solvent to form a solution, and mixing the solution to a soluble barium salt aqueous solution to form a first solution; providing a soluble sulfate aqueous solution with a pH value of 8 to 10, adding the soluble sulfate aqueous solution to the first solution to form a reaction to obtain a precipitate; separating, water washing, and drying the precipitate to obtain a nano-barium sulfate having a surface modified with a lithium carboxylate group; dispersing the nano-barium sulfate having the surface modified with the lithium carboxylate group in a second organic solvent to obtain a dispersing liquid; adding the gel polymer in the dispersing liquid to obtain the composite gel; and combining the composite gel with a base membrane.

10 . The method of claim 9 , wherein the first organic solvent is a water-soluble polar organic solvent, and a volume ratio of the water-soluble polar organic solvent and the soluble barium salt aqueous solution is in a range from about 1:1 to about 2:1.

11 . The method of claim 9 , wherein the lithium carboxylate is selected from the group consisting of lithium oleate, lithium stearate, lithium benzoate dodecyl, hexadecyl lithium benzoate, lithium polyacrylate, and combinations thereof.

12 . The method of claim 11 , wherein a mass of the lithium carboxylate is in a range from about 1% to about 5% of a mass of the nano-barium sulfate.

13 . The method of claim 9 , wherein the combining the composite gel with the base membrane comprising:
coating the composite gel on the base membrane to form a composite gel layer; immersing the base membrane with the composite gel layer in a pore-forming agent, to create pores in the composite gel layer; and drying the base membrane with the composite gel layer to obtain the composite separator.

14 . A lithium-ion battery, comprising:
a cathode; an anode; and a composite gel electrolyte film disposed between the cathode and the anode, the composite gel electrolyte film comprising a composite separator and a non-aqueous electrolyte liquid permeated in the composite separator, the composite separator comprising:
a base membrane; and
a composite gel composited with the base membrane, the composite gel comprising a gel polymer and a nano-barium sulfate dispersed in the gel polymer, and a surface of the nano-barium sulfate being modified with a lithium carboxylate group.

Assignees

• Jiangsu Huadong Inst Of Li-Ion Battery Co Ltd
• Univ Tsinghua
• Jiangsu Huadong Inst Of Li-Ion Battery Co Ltd

Inventors

• Shang yu-ming
• Ding xiao-lei
• He xiang-ming
• Wang Li
• Li Jian-Jun
• Wang yao-wu
• Gao Jian

Classifications

• H01M10/0525 Primary

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

• H01M50/497

  Ionic conductivity · CPC title

• H01M50/451

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

• H01M50/42

  Acrylic resins · CPC title

• H01M50/417

  Polyolefins · CPC title