Method for preparing separator for battery with gel polymer layer

1. A method for preparing a separator for a battery with a gel polymer layer on a substrate, wherein the gel polymer layer includes a plurality of three-dimensional open pores interconnected with each other, the method comprising the steps of:

applying a solution onto a substrate, wherein the solution contains a polymer dissolved in a solvent, wherein the polymer is capable of forming a gel; and

applying an atomized non-solvent to the solution during a step of heating the solution on the substrate to cause phase separation in the solution to form a plurality of three-dimensional open pores in a gel polymer layer, wherein the atomized non-solvent is a non-solvent for the polymer.

2. The method as claimed in claim 1 , wherein the heating of the solution is performed at a temperature of 50-130° C.

3. The method as claimed in claim 1 , wherein the polymer has a solubility parameter of 15-45 MPa 1/2 .

4. The method as claimed in claim 1 , wherein the polymer has a weight average molecular weight of 10,000-1,000,000 g/mol.

5. The method as claimed in claim 1 , wherein the solvent used for dissolving the polymer is acetone, tetrahydrofuran, methylene chloride, chloroform, dimethyl formamide, N-methyl-2-pyrrolidone, cyclohexane or a mixture thereof.

6. The method as claimed in claim 1 , wherein the non-solvent is selected from alcohols, water and mixtures thereof.

7. The method as claimed in claim 1 , wherein a concentration of the polymer ranges from 0.1-30 wt %, relative to the total weight of the solution.

8. The method as claimed in claim 1 , wherein a volume ratio of the non-solvent to the solvent is used ranges from 0.1-50.

9. The method as claimed in claim 1 , wherein the pores have an average diameter of 0.01-10 μm.

10. The method as claimed in claim 1 , wherein the substrate has a thickness of 1-100 μm and the gel polymer layer has a thickness of 0.1-10 μm.