Single fiber layer structure of micron or nano fibers and multi-layer structure of micron and nano fibers applied in separator for battery

1. A multi-layer structure of micron and nano fibers applied in a battery, comprising:

a web of micron fibers formed by a plurality of interweaved micron fibers whose diameter is greater than or equal to 1 μm;

a web of nano fibers formed by a plurality of nano fibers interweaved on the web of micron fibers, wherein the plurality of nano fibers have a diameter less than 1 μm;

a mixture layer of fibers located between the web of nano fibers and the web of micron fibers, wherein the mixture layer of fibers comprises parts of the plurality of interweaved nano and micron fibers; and

a resin at least impregnating the mixture layer of fibers and parts of the plurality of micron fibers of the web of micron fibers.

2. The multi-layer structure of micron and nano fibers according to claim 1 , having a pore size of 1 nm-700 nm and a porosity greater than or equal to 45%.

3. The multi-layer structure of micron and nano fibers according to claim 1 , having a porosity of 45%-80%.

4. The multi-layer structure of micron and nano fibers according to claim 1 , wherein, the web of micron fibers has a pore size of 10 nm-700 nm, and the web of nano fibers has a pore size of 10 nm-500 nm.

5. The multi-layer structure of micron and nano fibers according to claim 1 , wherein a weight ratio between the plurality of micron fibers, the plurality of nano fibers and the resin is 60-65:20:20-15.

6. The multi-layer structure of micron and nano fibers according to claim 1 , wherein the resin is polyvinylidene fluoride (PVDF) dissolved in N-Methyl-2-pyrrolidone (NMP) or polyacrylonitrile (PAN) dissolved in dimethylacetamide (DMAc).

7. The multi-layer structure of micron and nano fibers according to claim 1 , wherein the web of nano fibers formed by the plurality of nano fibers interweaved on the web of micron fibers is formed by electro-spinning a polymer solution, one side of the web of micron fibers is coated with a mixture solution containing the resin and is further water bathed to remove a solvent of the mixture solution to reduce the mixture layer of fibers and pore size of parts of the plurality of micron fibers of the web of micron fibers.

8. The multi-layer structure of micron and nano fibers according to claim 1 , wherein the plurality of micron fibers are formed by materials such as polyethylene terephthalate (PET), polyethylene (PE), or polypropylene (PP) polymer, and the plurality of nano fibers are formed by materials such as pitch fiber, PAN fiber, phenolic fiber or an ion polymer whose repeat unit is formed according to structural formulas [I] and [II]:

wherein, R 1 comprises benzene sulfonic acid, and R 2 is formed by materials selected from following group comprising:

R 3 represents amine or sulfonate, X represents chloride, bromide or iodide, m and n are numbers of repeat units, and m/n is between 1/99-99/1.

9. The multi-layer structure of micron and nano fibers according to claim 1 , wherein when a weight ratio between micron and nano fibers is between 10:5 and 10:10, the multi-layer structure of micron and nano fibers has a pore size of 1 nm-400 nm and an average pore size of 50 nm-200 nm.

10. The multi-layer structure of micron and nano fibers according to claim 1 , wherein the plurality of micron fibers have a diameter of 1 μm-10 μm, and the plurality of nano fibers have a diameter of 1 nm-700 nm.

11. The multi-layer structure of micron and nano fibers according to claim 1 , wherein the web of micron fibers has a thicknesss of 10 μm-25 μm, the web of nano fibers has a thickness of 1 μm-5 μm, and the multi-layer structure of micron and nano fibers has a thickness less than 30 μm.