One-step molded lithium ion battery separator, preparation method and application thereof

Abstract

A one-step molded lithium ion battery separator and preparation method and application thereof are provided. The battery separator comprises a support layer and a filler layer. The support layer comprises at least two of superfine main fiber, thermoplastic bonded fiber and first nanofiber, and the filler layer comprises at least one of inorganic fillers and third nanofiber. The lithium ion battery separator has a thickness of 19-31 μm, a maximum pore diameter of no more than 1 μm, and a heat shrinkage rate of less than 3% after treatment at 300° C. for 1 hour, and the separator still has a certain strength at a high temperature, ensuring stability and isolation of the rigid structure of the filler layer at a high temperature, satisfying requirements of the separator in terms of heat resistance, pore size and strength, having excellent comprehensive performance.

Claims

1. A one-step molded lithium ion battery separator, comprising a support layer, a dense layer and a filler layer, wherein, the dense layer is located between the support layer and the filler layer; the support layer comprises superfine main fiber in an amount of 3-6 g/m.sup.2, thermoplastic bonded fiber in an amount of 3-6 g/m.sup.2 and first nanofiber in an amount of 2-11 g/m.sup.2; the superfine main fiber is stretched polyethylene terephthalate fiber with a fiber diameter of 0.1-6 gm and a fiber length of 1-6 mm; the thermoplastic bonded fiber is unstretched polyethylene terephthalate fiber with a fiber diameter of 0.1-8 μm and a fiber length of 1-6 mm; the first nanofiber is selected from one or more of the group consisting of fibrillated poly-p-phenylene terephthalamide (PPTA) nanofiber and fibrillated lyocell nanofiber both with a beating degree of 70-95° SR; the dense layer consists of second nanofiber; the second nanofiber is in an amount of 2-12 g/m.sup.2; the second nanofiber is selected from one or more of the group consisting of fibrillated poly-p-phenylene terephthalamide (PPTA) nanofiber and fibrillated polyacrylonitrile (PAN) nanofiber; the second nanofiber has a beating degree of 60-85° SR; the filler layer comprises inorganic particles in an amount of 5-19 g/m.sup.2 and third nanofiber in an amount of 0-11 g/m.sup.2; the inorganic particles are alumina with a particle size of less than 3 μm; the third nanofiber has a beating degree of 60-85° SR; the third nanofiber is selected from one or more of the group consisting of fibrillated poly-p-phenylene terephthalamide nanofiber, fibrillated poly-p-phenylene benzodioxazole (PBO) nanofiber and fibrillated polyacrylonitrile nanofiber; a thickness of the separator is 19-26 μm; a basis weight of the separator is 15-30 g/m.sup.2; a maximum pore size of the separator is no more than 1.0 μm; a heat shrinkage rate of the separator is no more than 2.8% at 300° C.; a sum of the first nanofiber, the second nanofiber and the third nanofiber is not less than 4 g/m.sup.2.

2. The lithium ion battery separator according to claim 1, wherein, a a basis weight of the separator is 15-25 g/m.sup.2; the average pore size of the separator is 0.2-0.5 μm; a maximum pore size of the separator is 0.7-1 μm.

3. The lithium ion battery separator according to claim 1, wherein, a basis weight of the support layer is 8-14 g/m.sup.2; a basis weight of the filler layer is 5-16 g/m.sup.2.

4. A lithium ion battery comprising the lithium ion battery separator according to claim 1.

5. The lithium ion battery separator according to claim 1, wherein, a basis weight of the support layer is 8-11 g/m.sup.2; a basis weight of the filler layer is 5-9 g/m.sup.2; a basis weight of the dense layer is 2-8 g/m.sup.2.

6. The lithium ion battery separator according to claim 1, wherein, the superfine main fiber is stretched polyethylene terephthalate fiber with a fiber diameter of 0.5-4 μm and a fiber length of 2-4 mm.

7. The lithium ion battery separator according to claim 1, wherein, the thermoplastic bonded fiber is unstretched polyethylene terephthalate fiber with a fiber diameter of 0.5-6 μm and a fiber length of 2-4 mm.

8. The lithium ion battery separator according to claim 1, wherein, the first nanofiber has a beating degree of 95° SR.

9. The lithium ion battery separator according to claim 1, wherein, the second nanofiber has a beating degree of 85° SR.

10. The lithium ion battery separator according to claim 1, wherein, the inorganic particles are alumina with a particle size of less than 1 μm.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) Embodiments of the disclosure are described in detail below with reference to the attached drawing figures, wherein:

(2) FIG. 1 and FIG. 2 are schematic diagrams of the apparent morphologies of the lithium ion battery separators prepared by the disclosure.

(3) FIG. 3 is a schematic structural view of the Hydroformer with three-layer used in the disclosure, wherein A represents a pulp distributor, B represents a rectifying zone, C represents a forming zone, and D represents a formed wet paper sheet.

(4) FIG. 4 is a schematic structural view of the Hydroformer with double-layer used in the disclosure, wherein A represents a pulp distributor, B represents a rectifying zone, C represents a forming zone, and D represents a formed wet paper sheet.

DETAILED DESCRIPTION OF THE DISCLOSURE

(5) The disclosure will be further described below in conjunction with specific embodiments. It should be understood that the embodiments of the disclosure are only used to illustrate the disclosure, and are not intended to limit the scope of the disclosure.

(6) The experimental methods without specific conditions in the following examples are generally performed under conventional conditions or according to the conditions recommended by the manufacturer. Unless otherwise defined, all professional and scientific terms used in the text have the same meaning as familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to the described content can be applied to the method of the disclosure. The preferred implementation methods and materials described herein are for demonstration purposes only.

(7) The Hydroformer multi-layer inclined wire former, used in the disclosure, has hydraulic pressure control, pulp distributor and rectifying component, and adopts a multi-channel design; wherein, Examples 1-11, 14-20, 23-25 of the disclosure use the Hydroformer with three-layer shown in FIG. 3, and the appearance of the prepared lithium ion battery separator is shown in FIG. 1; Examples 12, 13, 21, 22 of the disclosure use the Hydroformer with double-layer shown in FIG. 4, and the appearance of the prepared lithium ion battery separator is shown in FIG. 2.

(8) The following Examples 1-25 and Comparative Examples 1-15 only disclose examples of using some fiber materials to prepare the lithium ion battery separators, and other fiber materials and combinations thereof given in the disclosure may also be used to prepare the lithium ion battery separators of the disclosure.

Example 1

(9) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 1. The separator is prepared by the following method:

(10) Step a: Mixing the fiber materials of the support layer, the dense layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 1, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer, the dense layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.026 wt % to obtain Pulp 1; the fiber material of the dense layer is diluted to a solid weight percent concentration of 0.040 wt % to obtain Pulp 2; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.140 wt % to obtain Pulp 3.

(11) Step b: Adjusting the position of the fins in the former to the flow channel close to the forming wire: the middle flow channel: the upper flow channel with the cross-sectional area ratio of (7:2:1); respectively feeding the diluted pulp of each layer into the Hydroformer, a three-layer hydraulic inclined wire former, wherein the pulp 1 enters the flow channel close to the forming wire at a flow rate of 700 m.sup.3/h, the pulp 2 enters the middle flow channel at a flow rate of 200 m.sup.3/h, the pulp 3 enters the upper flow channel at a flow rate of 100 m.sup.3/h; after rectification, making papers of the three layers at the same time, and draining to obtain a wet paper sheet.

(12) Step c: Drying the wet paper sheet obtained in step b to obtain a dry paper sheet for the separator at a temperature of 120° C. by a Yankee dryer.

(13) Step d: Calendering the dry paper sheet obtained in Step c at a temperature of 190° C. by a metal roller and a soft roller to obtain the lithium ion battery separator.

Example 2

(14) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 1. The separator is prepared by the following method:

(15) Step a: Mixing the fiber materials of the support layer, the dense layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 1, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer, the dense layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.031 wt % to obtain Pulp 1; the fiber material of the dense layer is diluted to a solid weight percent concentration of 0.020 wt % to obtain Pulp 2; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.140 wt % to obtain Pulp 3.

(16) Step b, Step c and Step d are the same as in Example 1.

Examples 3, 4

(17) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 1. The preparation method is the same as that in Example 2.

Example 5

(18) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 1. The separator is prepared by the following method:

(19) Step a: Mixing the fiber materials of the support layer, the dense layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 1, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer, the dense layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.023 wt % to obtain Pulp 1; the fiber material of the dense layer is diluted to a solid weight percent concentration of 0.020 wt % to obtain Pulp 2; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.100 wt % to obtain Pulp 3.

(20) Step b, Step c and Step d are the same as in Example 1.

Example 6

(21) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 1. The separator is prepared by the following method:

(22) Step a: Mixing the fiber materials of the support layer, the dense layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 1, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer, the dense layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.049 wt % to obtain Pulp 1; the fiber material of the dense layer is diluted to a solid weight percent concentration of 0.020 wt % to obtain Pulp 2; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.100 wt % to obtain Pulp 3.

(23) Step b, Step c and Step d are the same as in Example 1.

Example 7

(24) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 1. The separator is prepared by the following method:

(25) Step a: Mixing the fiber materials of the support layer, the dense layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 1, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer, the dense layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.030 wt % to obtain Pulp 1; the fiber material of the dense layer is diluted to a solid weight percent concentration of 0.048 wt % to obtain Pulp 2; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.100 wt % to obtain Pulp 3.

(26) Step b: Adjusting the position of the fins in the former to the flow channel close to the forming wire: the middle flow channel: the upper flow channel with the cross-sectional area ratio of (4:5:1); respectively feeding the diluted pulp of each layer into the Hydroformer, a three-layer hydraulic inclined wire former, wherein the pulp 1 enters the flow channel close to the forming wire at a flow rate of 400 m.sup.3/h, the pulp 2 enters the middle flow channel at a flow rate of 500 m.sup.3/h, the pulp 3 enters the upper flow channel at a flow rate of 100 m.sup.3/h; after rectification, making papers of the three layers at the same time, and draining to obtain a wet paper sheet.

(27) Step c and Step d are the same as in Example 1.

Example 8

(28) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 1. The separator is prepared by the following method:

(29) Step a: Mixing the fiber materials of the support layer, the dense layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 1, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer, the dense layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.023 wt % to obtain Pulp 1; the fiber material of the dense layer is diluted to a solid weight percent concentration of 0.020 wt % to obtain Pulp 2; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.380 wt % to obtain Pulp 3.

(30) Step b, Step c and Step d are the same as in Example 1.

Example 9

(31) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 1. The separator is prepared by the following method:

(32) Step a: Mixing the fiber materials of the support layer, the dense layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 1, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer, the dense layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.040 wt % to obtain Pulp 1; the fiber material of the dense layer is diluted to a solid weight percent concentration of 0.020 wt % to obtain Pulp 2; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.100 wt % to obtain Pulp 3.

(33) Step b, Step c and Step d are the same as in Example 1.

Examples 10, 11

(34) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 1. The preparation method is the same as that in Example 7.

Example 12

(35) A one-step molded lithium ion battery separator consists of a two-layer structure of a support layer and a filler layer. The formulas of the support layer and the filler layer are shown in Table 1. The separator is prepared by the following method:

(36) Step a: Mixing the fiber materials of the support layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 1, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.032 wt % to obtain Pulp 1; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.064 wt % to obtain Pulp 2.

(37) Step b: Adjusting the position of the fins in the former to the flow channel close to the forming wire: the upper flow channel with the cross-sectional area ratio of (5:5); respectively feeding the diluted pulp of each layer into the Hydroformer, a double-layer hydraulic inclined wire former, wherein the pulp 1 enters the flow channel close to the forming wire at a flow rate of 500 m.sup.3/h, the pulp 2 enters the middle flow channel at a flow rate of 500 m.sup.3/h; after rectification, making papers of the two layers at the same time, and draining to obtain a wet paper sheet.

(38) Step c and Step d are the same as in Example 1.

Example 13

(39) A one-step molded lithium ion battery separator consists of a two-layer structure of a support layer and a filler layer. The formulas of the support layer and the filler layer are shown in Table 1. The separator is prepared by the following method:

(40) Step a: Mixing the fiber materials of the support layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 1, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.040 wt % to obtain Pulp 1; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.047 wt % to obtain Pulp 2.

(41) Step b: Adjusting the position of the fins in the former to the flow channel close to the forming wire: the upper flow channel with the cross-sectional area ratio of (7:3); respectively feeding the diluted pulp of each layer into the Hydroformer, a double-layer hydraulic inclined wire former, wherein the pulp 1 enters the flow channel close to the forming wire at a flow rate of 700 m.sup.3/h, the pulp 2 enters the middle flow channel at a flow rate of 300 m.sup.3/h; after rectification, making papers of the two layers at the same time, and draining to obtain a wet paper sheet.

(42) Step c and Step d are the same as in Example 1.

Example 14

(43) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 1. The separator is prepared by the following method:

(44) Step a: Mixing the fiber materials of the support layer, the dense layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 1, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer, the dense layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.031 wt % to obtain Pulp 1; the fiber material of the dense layer is diluted to a solid weight percent concentration of 0.020 wt % to obtain Pulp 2; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.180 wt % to obtain Pulp 3.

(45) Step b, Step c and Step d are the same as in Example 1.

Examples 15, 16

(46) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 1. The preparation method is the same as that in Example 1.

Examples 17, 18, 19, 20, 23-25

(47) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 1. The separator is prepared by the following method:

(48) Step a and Step b are the same as in Example 2.

(49) Step c: Drying the wet paper sheet obtained in step b to obtain a dry paper sheet for the separator at a temperature of 90° C. by a Yankee dryer.

(50) Step d: Calendering the dry paper sheet obtained in Step c at a temperature of 120° C. by a metal roller and a soft roller to obtain the lithium ion battery separator.

Example 21, 22

(51) A one-step molded lithium ion battery separator consists of a two-layer structure of a support layer and a filler layer. The formulas of the support layer and the filler layer are shown in Table 1. The separator is prepared by the following method:

(52) Step a: Mixing the fiber materials of the support layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 1, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.031 wt % to obtain Pulp 1; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.06 wt % to obtain Pulp 2.

(53) Step b: Adjusting the position of the fins in the former to the flow channel close to the forming wire: the upper flow channel with the cross-sectional area ratio of (7:3); respectively feeding the diluted pulp of each layer into the Hydroformer, a double-layer hydraulic inclined wire former, wherein the pulp 1 enters the flow channel close to the forming wire at a flow rate of 700 m.sup.3/h, the pulp 2 enters the middle flow channel at a flow rate of 300 m.sup.3/h; after rectification, making papers of the two layers at the same time, and draining to obtain a wet paper sheet.

(54) Step c and Step d are the same as in Example 1.

Comparative Example 1

(55) A lithium ion battery separator consists of a single layer structure of a support layer. The formula of the support layer is shown in Table 2. The separator is prepared by the following method:

(56) Step a: Mixing the fiber material of the support layer with water in the defibizer according to the formula shown in Table 2, defiberizing to a solid weight percent concentration of 0.2 wt %, and then diluting the fiber material of the support layer by the flushing pump, wherein the fiber materials of the support layer are diluted to a solid weight percent concentration of 0.018 wt % to obtain Pulp 1.

(57) Step b: Feeding the diluted pulp into the Hydroformer, a hydraulic inclined wire former, wherein the flow rate is 1000 m.sup.3/h; rectifying and draining to obtain a wet paper sheet.

(58) Step c: Drying the wet paper sheet obtained in step b to obtain a dry paper sheet for the separator at a temperature of 120° C. by a Yankee dryer.

(59) Step d: Calendering the dry paper sheet obtained in Step c at a temperature of 190° C. by a metal roller and a soft roller to obtain the lithium ion battery separator.

Comparative Example 2

(60) A one-step molded lithium ion battery separator consists of a two-layer structure of a support layer and a dense layer. The formulas of the support layer and the dense layer are shown in Table 2. The separator is prepared by the following method:

(61) Step a: Mixing the fiber materials of the support layer and the dense layer respectively with water in the defibizer according to the formulas shown in Table 2, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer and the dense layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.026 wt % to obtain Pulp 1; the fiber material of the dense layer is diluted to a solid weight percent concentration of 0.027 wt % to obtain Pulp 2.

(62) Step b: Adjusting the position of the fins in the former to the flow channel close to the forming wire: the upper flow channel with the cross-sectional area ratio of (7:3); respectively feeding the diluted pulp of each layer into the Hydroformer, a double-layer hydraulic inclined wire former, wherein the pulp 1 enters the flow channel close to the forming wire at a flow rate of 700 m.sup.3/h, the pulp 2 enters the upper flow channel at a flow rate of 300 m.sup.3/h; after rectification, making papers of the two layers at the same time, and draining to obtain a wet paper sheet.

(63) Step c: Drying the wet paper sheet obtained in step b to obtain a dry paper sheet for the separator at a temperature of 120° C. by a Yankee dryer.

(64) Step d: Calendering the dry paper sheet obtained in Step c at a temperature of 190° C. by a metal roller and a soft roller to obtain the lithium ion battery separator.

Comparative Example 3

(65) A one-step molded lithium ion battery separator consists of a two-layer structure of a support layer and a filler layer. The formulas of the support layer and the filler layer are shown in Table 2. The separator is prepared by the following method:

(66) Step a: Mixing the fiber materials of the support layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 2, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.026 wt % to obtain Pulp 1; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.047 wt % to obtain Pulp 2.

(67) Step b: Adjusting the position of the fins in the former to the flow channel close to the forming wire: the upper flow channel with the cross-sectional area ratio of (7:3); respectively feeding the diluted pulp of each layer into the Hydroformer, a double-layer hydraulic inclined wire former, wherein the pulp 1 enters the flow channel close to the forming wire at a flow rate of 700 m.sup.3/h, the pulp 2 enters the upper flow channel at a flow rate of 300 m.sup.3/h; after rectification, making papers of the two layers at the same time, and draining to obtain a wet paper sheet.

(68) Step c and Step d are the same as in Comparative Example 1.

Comparative Example 4

(69) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 2. The separator is prepared by the following method:

(70) Step a: Mixing the fiber materials of the support layer, the dense layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 2, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer, the dense layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.026 wt % to obtain Pulp 1; the fiber material of the dense layer is diluted to a solid weight percent concentration of 0.030 wt % to obtain Pulp 2; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.100 wt % to obtain Pulp 3.

(71) Step b: Adjusting the position of the fins in the former to the flow channel close to the forming wire: the middle flow channel: the upper flow channel with the cross-sectional area ratio of (7:2:1); respectively feeding the diluted pulp of each layer into the Hydroformer, a three-layer hydraulic inclined wire former, wherein the pulp 1 enters the flow channel close to the forming wire at a flow rate of 700 m.sup.3/h, the pulp 2 enters the middle flow channel at a flow rate of 200 m.sup.3/h, the pulp 3 enters the upper flow channel at a flow rate of 100 m.sup.3/h; after rectification, making papers of the three layers at the same time, and draining to obtain a wet paper sheet.

(72) Step c and Step d are the same as in Comparative Example 1.

Comparative Example 5

(73) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 2. The separator is prepared by the following method:

(74) Step a: Mixing the fiber materials of the support layer, the dense layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 2, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer, the dense layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.029 wt % to obtain Pulp 1; the fiber material of the dense layer is diluted to a solid weight percent concentration of 0.020 wt % to obtain Pulp 2; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.100 wt % to obtain Pulp 3.

(75) Step b, Step c and Step d are the same as in Comparative Example 4.

Comparative Example 6

(76) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 2. The separator is prepared by the following method:

(77) Step a: Mixing the fiber materials of the support layer, the dense layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 2, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer, the dense layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.031 wt % to obtain Pulp 1; the fiber material of the dense layer is diluted to a solid weight percent concentration of 0.010 wt % to obtain Pulp 2; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.100 wt % to obtain Pulp 3.

(78) Step b, Step c and Step d are the same as in Comparative Example 4.

Comparative Example 7

(79) A one-step molded lithium ion battery separator consists of a two-layer structure of a support layer and a filler layer. The formulas of the support layer and the filler layer are shown in Table 2. The separator is prepared by the following method:

(80) Step a: Mixing the fiber materials of the support layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 2, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.029 wt % to obtain Pulp 1; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.047 wt % to obtain Pulp 2.

(81) Step b, Step c and Step d are the same as in Comparative Example 3.

Comparative Example 8

(82) A one-step molded lithium ion battery separator consists of a two-layer structure of a support layer and a filler layer. The formulas of the support layer and the filler layer are shown in Table 2. The separator is prepared by the following method:

(83) Step a: Mixing the fiber materials of the support layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 2, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.045 wt % to obtain Pulp 1; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.070 wt % to obtain Pulp 2.

(84) Step b: Adjusting the position of the fins in the former to the flow channel close to the forming wire: the upper flow channel with the cross-sectional area ratio of (4:1); respectively feeding the diluted pulp of each layer into the Hydroformer, a double-layer hydraulic inclined wire former, wherein the pulp 1 enters the flow channel close to the forming wire at a flow rate of 800 m.sup.3/h, the pulp 2 enters the upper flow channel at a flow rate of 200 m.sup.3/h; after rectification, making papers of the two layers at the same time, and draining to obtain a wet paper sheet.

(85) Step c and Step d are the same as in Comparative Example 1.

Comparative Example 9

(86) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 2. The separator is prepared by the following method:

(87) Step a: Mixing the fiber materials of the support layer, the dense layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 2, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer, the dense layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.040 wt % to obtain Pulp 1; the fiber material of the dense layer is diluted to a solid weight percent concentration of 0.043 wt % to obtain Pulp 2; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.100 wt % to obtain Pulp 3.

(88) Step b: Adjusting the position of the fins in the former to the flow channel close to the forming wire: the middle flow channel: the upper flow channel with the cross-sectional area ratio of (3:6:1); respectively feeding the diluted pulp of each layer into the Hydroformer, a three-layer hydraulic inclined wire former, wherein the pulp 1 enters the flow channel close to the forming wire at a flow rate of 300 m.sup.3/h, the pulp 2 enters the middle flow channel at a flow rate of 600 m.sup.3/h, the pulp 3 enters the upper flow channel at a flow rate of 100 m.sup.3/h; after rectification, making papers of the three layers at the same time, and draining to obtain a wet paper sheet.

(89) Step c and Step d are the same as in Comparative Example 1.

Comparative Example 10

(90) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 2. The separator is prepared by the following method:

(91) Step a: Mixing the fiber materials of the support layer, the dense layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 2, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer, the dense layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.031 wt % to obtain Pulp 1; the fiber material of the dense layer is diluted to a solid weight percent concentration of 0.050 wt % to obtain Pulp 2; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.080 wt % to obtain Pulp 3.

(92) Step b, Step c and Step d are the same as in Comparative Example 4.

Comparative Example 11

(93) A one-step molded lithium ion battery separator consists of a two-layer structure of a support layer and a filler layer. The formulas of the support layer and the filler layer are shown in Table 2. The separator is prepared by the following method:

(94) Step a: Mixing the fiber materials of the support layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 2, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.023 wt % to obtain Pulp 1; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.147 wt % to obtain Pulp 2.

(95) Step b, Step c and Step d are the same as in Comparative Example 3.

Comparative Example 12, 13

(96) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 2. The separator is prepared by the following method:

(97) Step a: Mixing the fiber materials of the support layer, the dense layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 2, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer, the dense layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.046 wt % to obtain Pulp 1; the fiber material of the dense layer is diluted to a solid weight percent concentration of 0.020 wt % to obtain Pulp 2; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.100 wt % to obtain Pulp 3.

(98) Step b, Step c and Step d are the same as in Comparative Example 4.

Comparative Examples 14, 15

(99) A one-step molded lithium ion battery separator consists of a three-layer structure of a support layer, a dense layer and a filler layer. The formulas of the support layer, the dense layer and the filler layer are shown in Table 2. The separator is prepared by the following method:

(100) Step a: Mixing the fiber materials of the support layer, the dense layer and the filler layer respectively with water in the defibizer according to the formulas shown in Table 2, defiberizing and beating to a solid weight percent concentration of 0.2 wt %, and then respectively diluting the fiber materials of the support layer, the dense layer and the filler layer by the flushing pump, wherein the fiber material of the support layer is diluted to a solid weight percent concentration of 0.043 wt % to obtain Pulp 1; the fiber material of the dense layer is diluted to a solid weight percent concentration of 0.020 wt % to obtain Pulp 2; the fiber material of the filler layer is diluted to a solid weight percent concentration of 0.100 wt % to obtain Pulp 3.

(101) Step b, Step c and Step d are the same as in Comparative Example 4.

(102) TABLE-US-00001 TABLE 1 Fiber material formulations of Examples 1-25 (g/m.sup.2) Superfine Thermoplastic First Second Third Inorganic Examples main fiber bonded fiber nanofiber nanofiber nanofiber particles Example 1 Support layer 5 .sup.a) 4 .sup.d) — — — — Dense layer — — — 4 .sup.h) — — Filler layer — — — — — 7 .sup.k) Example 2 Support layer 5 .sup.a) 4 .sup.d) 2 .sup.g) — — — Dense layer — — — 2 .sup.h) — — Filler layer — — — — — 7 .sup.k) Example 3 Support layer 5 .sup.a) 4 .sup.d) 2 .sup.h) — — — Dense layer — — — 2 .sup.g) — — Filler layer — — — — — 7 .sup.k) Example 4 Support layer 5 .sup.a) 4 .sup.d) 2 .sup.h) — — — Dense layer — — — 2 .sup.h) — — Filler layer — — — — — 7 .sup.k) Example 5 Support layer 3 .sup.a) 3 .sup.d) 2 .sup.g) — — — Dense layer — — — 2 .sup.h) — — Filler layer — — — — — 5 .sup.k) Example 6 Support layer 3 .sup.a) 3 .sup.d) 11 .sup.g)  — — — Dense layer — — — 2 .sup.h) — — Filler layer — — — — — 5 .sup.k) Example 7 Support layer 3 .sup.a) 3.sup.d) — — — — Dense layer — — — 12 .sup.h)  — — Filler layer — — — — — 5 .sup.k) Example 8 Support layer 3 .sup.a) 3 .sup.d) 2 .sup.g) — — — Dense layer — — — 2 .sup.h) — — Filler layer — — — — — 19 .sup.k)  Example 9 Support layer 3 .sup.a) 9 .sup.d) 2 .sup.g) — — — Dense layer — — — 2 .sup.h) — — Filler layer — — — — — 5 .sup.k) Example 10 Support layer 9 .sup.a) 3 .sup.d) 2 .sup.g) — — — Dense layer — — — 2 .sup.h) — — Filler layer — — — — — 5 .sup.k) Example 11 Support layer 6 .sup.a) 6 .sup.d) 2 .sup.g) — — — Dense layer — — — 2 .sup.h) — — Filler layer — — — — — 5 .sup.k) Example 12 Support layer 3 .sup.a) 3 .sup.d) 2 .sup.g) — — — Filler layer — — — — 11 .sup.h)  5 .sup.k) Example 13 Support layer 6 .sup.a) 6 .sup.d) 2 .sup.g) — — — Filler layer — — — — 2 .sup.h) 5 .sup.k) Example 14 Support layer 5 .sup.a) 4 .sup.d) 2 .sup.g) — — — Dense layer — — — 2 .sup.h) — — Filler layer — — — — 2 .sup.h) 7 .sup.k) Example 15 Support layer 5 .sup.b) 4 .sup.d) 2 .sup.g) — — — Dense layer — — — 2 .sup.h) — — Filler layer — — — — — 7 .sup.k) Example 16 Support layer 5 .sup.c) 4 .sup.d) 2 .sup.g) — — — Dense layer — — — 2 .sup.h) — — Filler layer — — — — — 7 .sup.k) Example 17 Support layer 5 .sup.a) 4 .sup.e) 2 .sup.g) — — — Dense layer — — — 2 .sup.h) — — Filler layer — — — — — 7 .sup.k) Example 18 Support layer 5 .sup.a) 4 .sup.f) 2 .sup.g) — — — Dense layer — — — 2 .sup.h) — — Filler layer — — — — — 7 .sup.k) Example 19 Support layer 5 .sup.a) 4 .sup.b) 2 .sup.g) — — — Dense layer — — — 2 .sup.i) — — Filler layer — — — — — 7 .sup.k) Example 20 Support layer 5 .sup.a) 4 .sup.b) 2 .sup.g) — — — Dense layer — — — 2 .sup.j) — — Filler layer — — — — — 7 .sup.k) Example 21 Support layer 5 .sup.a) 4 .sup.b) 2 .sup.g) — — — Filler layer — — — — 2 .sup.i) 7 .sup.k) Example 22 Support layer 5 .sup.a) 4 .sup.b) 2 .sup.g) — — — Filler layer — — — — 2 .sup.j) 7 .sup.k) Example 23 Support layer 5 .sup.a) 4 .sup.b) 2 .sup.g) — — — Dense layer — — — 2 .sup.h) — — Filler layer — — — — — 7 .sup.l) Example 24 Support layer 5 .sup.a) 4 .sup.b) 2 .sup.g) — — — Dense layer — — — 2 .sup.h) — — Filler layer — — — — — 7 .sup.m) Example 25 Support layer 5 .sup.a) 4 .sup.b) 2 .sup.g) — — — Dense layer — — — 2 .sup.h) — — Filler layer — — — — — 7 .sup.n) Note: .sup.a) Stretched PET fiber with a fiber diameter of 2 μm and a fiber length of 3 mm; .sup.b) PAN fiber with a fiber diameter of 2 μm and a fiber length of 3 mm; .sup.c) PA fiber with a fiber diameter of 2 μm and a fiber length of 3 mm; .sup.d) Unstretched PET fiber with a fiber diameter of 4 μm and a fiber length of 3 mm; .sup.e) PET/co-PET bi-component fiber with a fiber diameter of 4 μm and a fiber length of 3 mm; .sup.f) PP/PE bi-component fiber with a fiber diameter of 4 μm and a fiber length of 3 mm; .sup.g) Fibrillated Tencel nanofiber with a beating degree of 95° SR, Lenzing, Austria; .sup.h) Fibrillated PPTA nanofiber with a beating degree of 85° SR, DuPont Kevlar of the United States; .sup.i) Fibrillated PBO nanofiber with a beating degree of 85° SR, Japan Toyobo Company; .sup.j) Fibrillated PAN nanofiber with a beating degree of 85° SR; .sup.k) Alumina nanoparticles with an average diameter of 200 nm; .sup.l) Silica nanoparticles with an average diameter of 200 nm; .sup.m) Boehmite nanoparticles with an average diameter of 200 nm; .sup.n) Magnesium hydroxide nanoparticles with an average diameter of 200 nm.

(103) TABLE-US-00002 TABLE 2 Fiber material formulations of Comparative Examples 1-15 (g/m.sup.2) Comparative Superfine Thermoplastic First Second Third Inorganic Examples main fiber bonded fiber nanofiber nanofiber nanofiber particles Comparative Support layer 5 .sup.a) 4 .sup.b) — — — — Example 1 Comparative Support layer 5 .sup.a) 4 .sup.b) — — — — Example 2 Dense layer — — — 4 .sup.d) — — Support layer 5 .sup.a) 4 .sup.b) — — — — Comparative Filler layer — — — — — 7 .sup.e) Example 3 Comparative Support layer 5 .sup.a) 4 .sup.b) — — — — Example 4 Dense layer — — — 3 .sup.d) — — Filler layer — — — — — 7 .sup.e) Comparative Support layer 5 .sup.a) 4 .sup.b) 1 .sup.c) — — — Example 5 Dense layer — — — 2 .sup.d) — — Filler layer — — — — — 7 .sup.e) Comparative Support layer 5 .sup.a) 4 .sup.b) 2 .sup.c) — — — Example 6 Dense layer — — — 1 .sup.d) — — Filler layer — — — — — 7 .sup.e) Comparative Support layer 5 .sup.a) 4 .sup.b) 1 .sup.c) — — — Example 7 Filler layer — — — — 2 .sup.d) 7 .sup.e) Comparative Support layer 3 .sup.a) 3 .sup.b) 12 .sup.c)  — — — Example 8 Filler layer — — — — 2 .sup.d) 5 .sup.e) Comparative Support layer 3 .sup.a) 3 .sup.b) — — — — Example 9 Dense layer — — — 13 .sup.d)  — — Filler layer — — — — — 5 .sup.e) Comparative Support layer 5 .sup.a) 4 .sup.b) 2 .sup.d) — — — Example 10 Dense layer — — — 5 .sup.d) — — Filler layer — — — — — 4 .sup.e) Comparative Support layer 3 .sup.a) 3 .sup.b) 2 .sup.c) — — — Example 11 Filler layer — — — — 2 .sup.d) 20 .sup.e)  Comparative Support layer 3 .sup.a) 2 .sup.b) 11 .sup.c)  — — — Example 12 Dense layer — — — 2 .sup.d) — — Filler layer — — — — — 5 .sup.e) Comparative Support layer 2 .sup.a) 3 .sup.b) 11 .sup.c)  — — — Example 13 Dense layer — — — 2 .sup.d) — — Filler layer — — — — — 5 .sup.e) Comparative Support layer 3 .sup.a) 10 .sup.b)  2 .sup.c) — — — Example 14 Dense layer — — — 2 .sup.d) — — Filler layer — — — — — 5 .sup.e) Comparative Support layer 10 .sup.a)  3 .sup.b) 2 .sup.c) — — — Example 15 Dense layer — — — 2 .sup.d) — — Filler layer — — — — — 5 .sup.e) Note: .sup.a) Stretched PET fiber with a fiber diameter of 2 μm and a fiber length of 3 mm; .sup.b) Unstretched PET fiber with a fiber diameter of 4 μm and a fiber length of 3 mm; .sup.c) Fibrillated Tencel nanofiber with a beating degree of 95° SR, Lenzing, Austria; .sup.d) Fibrillated PPTA nanofiber with a beating degree of 85° SR, DuPont Kevlar of the United States; .sup.e) Alumina nanoparticles with an average diameter of 200 nm.

(104) Performance Test of the Lithium Ion Battery Separator

(105) The lithium ion battery separators prepared in Examples 1-25 and Comparative Examples 1-15 were tested for performance. The test items and methods are as follows:

(106) 1. Basis weight, thickness and tensile strength: measured by TAPPI standard.

(107) 2. Average pore size and maximum pore size: measured using a PMI pore size analyzer.

(108) 3. Heat shrinkage rate

(109) The dimensional stability of the separator at a certain temperature can be characterized by the thermal stability of the separator, usually expressed in heat shrinkage rate. Test of the heat shrinkage rate of the separator as follows:

(110) Cutting the separator into squares with side length L.sub.b, and then respectively placing the separator in an environment of 110° C. and 300° C. for 1 hour, testing the side length L.sub.a of the separator, and calculating the shrinkage rate according to the following formula:
Shrinkage rate (%)=(L.sub.b−L.sub.a)/L.sub.b×100

(111) 4. Separator strength retention

(112) The separator was placed in a 300° C. environment for 1 hour and taken out. The strength retention of the separator was evaluated according to the following criteria:

(113) ∘: Fold the separator 10 times without breaking;

(114) Δ: Fold the separator 2-10 times and break;

(115) x: Fold the separator once and break.

(116) TABLE-US-00003 TABLE 3 Performance test parameters of the lithium ion battery separator of the disclosure Basis weight of Heat finished Tensile Average Maximum Shrinkage separators Thickness Strength Pore Size Pore Size Rate % at Strength Parameters g/m.sup.2 μm N/m μm μm 300° C. Retention Example 1 20.2 25.8 1203 0.28 0.76 1.8 ◯ Example 2 20.1 25.7 1235 0.23 0.68 1.8 ◯ Example 3 20.2 25.7 1222 0.26 0.74 2.0 ◯ Example 4 20.2 25.7 1208 0.27 0.76 1.8 ◯ Example 5 15.1 19.2 608 0.35 0.97 2.8 ◯ Example 6 24.3 29.9 753 0.30 0.88 2.7 ◯ Example 7 23.2 29.4 674 0.32 0.91 2.5 ◯ Example 8 28.9 29.9 652 0.22 0.79 0.8 ◯ Example 9 21.2 29.2 1506 0.30 0.90 2.8 ◯ Example 10 21.1 29.2 902 0.31 0.90 2.8 ◯ Example 11 21.2 29.4 1354 0.32 0.91 2.8 ◯ Example 12 24.1 29.6 705 0.33 0.95 2.5 ◯ Example 13 20.8 29.2 1353 0.30 0.90 2.8 ◯ Example 14 21.9 28.2 1257 0.23 0.80 1.5 ◯ Example 15 20.2 25.5 1208 0.25 0.85 1.8 ◯ Example 16 20.3 25.3 1202 0.26 0.86 1.8 ◯ Example 17 20.1 25.9 1189 0.26 0.88 1.8 ◯ Example 18 20.4 25.8 1197 0.26 0.87 1.8 ◯ Example 19 19.8 25.7 1221 0.28 0.88 1.8 ◯ Example 20 20.1 25.9 1219 0.26 0.86 1.8 ◯ Example 21 20.2 26.2 1220 0.26 0.88 1.8 ◯ Example 22 19.7 25.8 1218 0.25 0.87 1.8 ◯ Example 23 19.6 25.7 1222 0.24 0.80 1.8 ◯ Example 24 19.3 25.7 1218 0.25 0.78 1.8 ◯ Example 25 20.1 25.7 1215 0.24 0.81 1.8 ◯ Note: The lithium ion battery separator of the disclosure has a heat shrinkage rate of zero at 110° C.

(117) TABLE-US-00004 TABLE 4 Performance test parameters of the lithium ion battery separator Heat Basis Tensile Average Maximum Shrinkage weight Thickness Strength Pore Size Pore Size Rate % at Strength Parameters g/m.sup.2 μm N/m μm μm 300° C. Retention Comparative 9.2 15.5 865 5.8 44 Melting X Example 1 Comparative 12.9 20.5 913 1.42 2.45 4.5 Δ Example 2 Comparative 9.8 16.0 853 5.43 40 Melting X Example 3 Comparative 17.1 22.9 1105 0.28 1.32 1.8 ◯ Example 4 Comparative 17.2 22.6 1110 0.27 1.29 1.8 ◯ Example 5 Comparative 17.3 22.4 1128 0.26 1.18 2.0 Δ Example 6 Comparative 17.1 22.5 1112 0.27 1.38 1.8 ◯ Example 7 Comparative 25.1 31.1 763 0.30 0.88 2.8 ◯ Example 8 Comparative 24.1 30.7 681 0.32 0.91 2.5 ◯ Example 9 Comparative 20.0 27.2 1274 0.45 1.32 3.8 ◯ Example 10 Comparative 30.1 30.7 657 0.21 0.75 2.8 ◯ Example 11 Comparative 22.8 28.2 454 0.31 0.88 2.8 ◯ Example 12 Comparative 22.9 28.2 548 0.32 0.91 2.8 ◯ Example 13 Comparative 21.9 30.9 1504 0.32 0.88 2.8 ◯ Example 14 Comparative 21.7 30.6 908 0.32 0.93 2.8 ◯ Example 15

(118) It can be seen from Table 3 that the lithium ion battery separators obtained in Examples 1-25 of the disclosure have a thickness less than 30 μm. The separators have a multi-layer structure, comprising a support layer, a filler layer and/or a dense layer. The maximum pore size of the lithium ion battery separators is less than 1 μm, the strength is more than 600 N/m, and the filler particles do not drop-off. The heat shrinkage rate at 110° C. is zero, and the separators still have a certain strength at 300° C. for 1 hour and the heat shrinkage rate is less than 3.0%, and thus the separators have excellent thermal stability.

(119) It can be seen from Table 4 that in Comparative Example 1, the separator is only made of PET fiber, wherein the pore size is larger, and the separator melts at 300° C.; in Comparative Example 2, the separator without inorganic nanofillers has large pore size, and the heat shrinkage rate of the separator is more than 3.0% after treatment at 300° C. for 1 h; in Comparative Example 3, no nanofiber is used, and the PET fiber has large pores, which cannot effectively trap inorganic nanofiller particles, so that the separator obtained have pinholes, the pore size is large, and the separator melts at 300° C.; in Comparative Examples 4, 5, 6 and 7, the total amount of the nanofiber is less than 4 g/m.sup.2, the inorganic nanofiller particles are reduced in the forming zone, which cannot effectively cover the fiber layer, resulting in a larger pore size of the separator and a more loss of the basis weight; in Comparative Examples 8, 9, 11, 14 and 15, the thickness of the separator is more than 30 μm, which is not conducive to the control of the volume and energy density of batteries; in Comparative Example 10, the amount of the inorganic particles in the filler layer is less than 5 g/m.sup.2, which cannot effectively cover the fiber layer, resulting in a larger pore size of the separator; in Comparative Examples 12 and 13, the amount of PET fiber is too few so that the strength of the separator cannot meet the requirements.

(120) It should be understood that the disclosure described herein is not limited to specific methodologies, experimental protocols, or reagents, as these may vary. The discussion and examples provided herein are presented to describe specific embodiments and are not intended to limit the scope of the disclosure, which is limited only by the claims.