Sponge for new energy battery separator and preparation method thereof

Abstract

The present application relates to the technical field of sponge manufacturing, in particular to a sponge for new energy battery diaphragm and a preparation method thereof.The sponge for new energy battery diaphragm is prepared from the following raw materials in parts by weight: 40-45 parts of HDPE, 53-58 parts of paraffin oil, 0.15-0.8 parts of antioxidant, 0.05-0.5 parts of lubricant, 1-3 parts of toughening agent; the HDPE has a weight average molecular weight of 200000-250000 g / mol; and the sponge further comprises 5-7 parts of modified basalt fiber and 13-15 parts of modified glass fiber.The sponge for new energy battery diaphragm of the present application uses paraffin oil as a pore-forming agent, and the combination of the toughening agent, modified basalt fiber and modified glass fiber makes the prepared sponge meet the use requirements in terms of porosity, micropore size and tensile strength.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sponge manufacturing, in particular to a sponge for new energy battery diaphragm and a preparation method thereof. BACKGROUND

[0002] In the field of batteries (especially lithium ion batteries), the diaphragm as a key component needs to have good puncture resistance, stretch resistance, air permeability and other properties at the same time, and its performance directly determines the safety and cycle life of the battery.

[0003] Traditional diaphragms (such as polyolefin diaphragms) are prone to stretching, tearing or even diaphragm rupture during battery assembly extrusion, charge and discharge, or under high temperature environment, which directly causes short circuit. If there is a gap between the diaphragm and the positive and negative electrode surfaces, the internal resistance of the battery will increase, and local lithium may be precipitated due to uneven electrolyte infiltration. If the diaphragm can be effectively supported by the sponge to make up for the lack of mechanical strength, the use stability of the battery diaphragm can be effectively improved. SUMMARY

[0004] In view of the shortcomings of the prior art, the purpose of the present application is to provide a sponge for new energy battery diaphragm and a preparation method thereof, which aims to improve the use stability of the battery diaphragm by using the sponge as a support.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] A sponge for new energy battery diaphragm, the preparation raw materials of which include the following components in parts by weight: 40-45 parts of HDPE, 53-58 parts of paraffin oil, 0.15-0.8 parts of antioxidant, 0.05-0.5 parts of lubricant, 1-3 parts of toughening agent; the weight average molecular weight of the HDPE is 200000-250000 g / mol; further including 5-7 parts of modified basalt fiber and 13-15 parts of modified glass fiber.

[0007] The sponge for new energy battery diaphragm, wherein the antioxidant includes hindered phenolic antioxidant and phosphite antioxidant.

[0008] The sponge for new energy battery diaphragm, wherein the lubricant includes one or both of stearic acid amide and erucic acid amide.

[0009] The sponge for new energy battery diaphragm, wherein the toughening agent includes one or both of EVA and POE.

[0010] A preparation method of a sponge for new energy battery diaphragm, which is used to prepare the sponge for new energy battery diaphragm as described above, comprising the following steps:

[0011] S01. Mix the sponge preparation raw materials according to the formula, and put them into a screw extruder to perform melt extrusion under the condition of 180-230 DEG C;

[0012] S02. Rapidly cool the extruded sponge;

[0013] S03. Bidirectional stretching: first longitudinal stretching at 60-90 DEG C, and then transverse stretching at 90-120 DEG C;

[0014] S04. Removing paraffin oil: using organic solvent to soak or spray the stretched sponge to remove the paraffin oil in the sponge, so as to obtain the sponge for new energy battery diaphragm;

[0015] S05. Drying the sponge to remove residual solvent;

[0016] S06. Heat setting and slitting.

[0017] The preparation method of the sponge for new energy battery diaphragm, wherein in S02, the sponge is rapidly cooled to 20-40 DEG C.

[0018] The preparation method of the sponge for new energy battery diaphragm, wherein in S03, the sponge is longitudinally stretched by 2-4 times, and transversely stretched by 3-5 times.

[0019] The preparation method of the sponge for new energy battery diaphragm, wherein in S04, the organic solvent is selected from hexane or dichloromethane.

[0020] The preparation method of the sponge for new energy battery diaphragm, wherein in S05, the drying temperature is 80-120 DEG C.

[0021] The preparation method of the sponge for new energy battery diaphragm, wherein in S06, the heat setting temperature is 120-140 DEG C.

[0022] Beneficial effects: the present application provides a sponge for new energy battery diaphragm and a preparation method thereof, the sponge formed by using paraffin oil as a pore forming agent and HDPE as a skeleton material has micropores with small pore size and uniform distribution, meets the ion conduction requirement, and cooperates with modified basalt fiber, modified glass fiber and toughening agent to further improve the tensile property and mechanical strength of the sponge, realize performance complementation and cost optimization, retain the high temperature resistance and high strength advantages of the modified basalt fiber, and reduce the cost and improve the uniformity of the basalt fiber distribution by means of the modified glass fiber and the toughening agent, and improve the support performance of the sponge on the diaphragm. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The sponge prepared in Example 1 is shown in the figure. DETAILED DESCRIPTION

[0024] The present application provides a sponge for new energy battery separator and a preparation method thereof. In order to make the purpose, technical scheme and effect of the present application more clear and explicit, the present application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0025] The present application provides a sponge for new energy battery separator, and the preparation raw materials thereof include the following components in parts by weight: 40-45 parts of HDPE, 53-58 parts of paraffin oil, 0.15-0.8 parts of antioxidant, 0.05-0.5 parts of lubricant, 1-3 parts of toughening agent; the weight average molecular weight of the HDPE is 200000-250000 g / mol; further including 5-7 parts of modified basalt fiber and 13-15 parts of modified glass fiber. The present scheme takes HDPE as the base material, and the melting point of HDPE is 135℃, and the impact resistance is relatively good. In the wet preparation process, at a temperature higher than the melting point of the polymer (the melting point of HDPE is 135℃), the HDPE molecular chain fully stretches due to thermal motion, and the paraffin oil can be completely miscible with the HDPE, forming a thermodynamically stable uniform transparent solution. At this time, the polymer and the diluent molecules in the system are uniformly dispersed, and there is no obvious phase interface. When the system is cooled to a specific interval (usually between the melting point of the polymer and the glass transition temperature), the molecular thermal motion is weakened, and the compatibility of the polymer and the diluent decreases sharply, and the system tends to change from a high-energy homogeneous state to a low-energy phase-separated state, thereby phase separation occurs. During the phase separation process, the system will spontaneously separate into two continuous phases, one is the polymer-rich phase, which is formed by the mutual aggregation of HDPE molecular chains, forming a continuous three-dimensional network skeleton (containing a small amount of diluent); the other is the diluent-rich phase, i.e. paraffin oil fills in the voids of the polymer skeleton in the form of continuous droplets or channels. This "double continuous phase" structure is the basis for the subsequent porous morphology. The system after phase separation is treated through solidification and extraction, and finally forms a porous sponge-like structure.

[0026] Among the other components in the formula, the toughening agent is used to improve the toughness of the sponge, so that the structure is not easily damaged when stretched. The modified basalt fiber does not contain alkali metal, and is resistant to acid and alkali and electrolyte corrosion; the modified glass fiber has good acid resistance but weak alkali resistance. After compounding, the modified basalt fiber can "make up" for the shortcoming of the modified glass fiber in alkali resistance. At the same time, the flexibility of the modified glass fiber is better than that of the modified basalt fiber, and the compatibility with the polymer matrix PE is better, and it is easy to disperse and compound; the modified basalt fiber is relatively rigid and is prone to agglomeration when used alone, increasing the difficulty of sponge preparation. After compounding, the modified glass fiber can act as a dispersant and a flexibility agent, improving the uniformity of the distribution of the modified basalt fiber in the sponge, reducing the agglomeration phenomenon, and at the same time improving the flexibility of the sponge.

[0027] Specifically, the thickness of the modified basalt fiber is 3-5 microns, which is modified by soaking in a 2% silane coupling agent solution for 1 hour, and then dried and mixed with other raw material components. Similarly, the modified glass fiber is also modified by soaking in a 2% silane coupling agent solution for 1 hour to improve compatibility with other components.

[0028] Preferably, the antioxidant includes a hindered phenolic antioxidant and a phosphite antioxidant. The hindered phenolic antioxidant can actively capture free radicals generated during the processing or use of the sponge, terminate the oxidation chain reaction, and inhibit thermal oxidation aging of the sponge from the source. The phosphite antioxidant can decompose peroxide generated during the oxidation of the sponge into harmless alcohol or ester substances, avoiding further initiation of free radical reactions and forming a synergistic antioxidant effect with the hindered phenolic antioxidant.

[0029] Preferably, the hindered phenolic antioxidant is antioxidant 1010, and the amount used is 0.1-0.5 parts; the phosphite antioxidant is antioxidant 168, and the amount used is 0.05-0.3 parts.

[0030] Preferably, the lubricant includes one or both of stearic acid amide and erucic acid amide. The lubricant can form a lubricating film between the molecules of the sponge during high-temperature foaming or forming of the sponge, reduce the melt viscosity, and reduce equipment friction.

[0031] Preferably, the toughening agent includes one or both of EVA and POE. The vinyl acetate (VA) segment in the EVA molecule can form a flexible region, significantly reducing the brittleness of the sponge, making it less likely to crack when impacted or squeezed, and improving durability. POE has an elastomer structure and good compatibility with polyolefin substrates, and can be uniformly dispersed in the form of microfibers or particles, significantly improving the impact resistance of the sponge.

[0032] A method for preparing a sponge for a new energy battery separator, comprising the following steps:

[0033] S01. Mix the raw materials for preparing the sponge according to the formula and put them into a screw extruder for melt extrusion at a temperature of 180-230°C; after mixing the raw materials, the HDPE and paraffin oil form a two-phase structure in the melt state, and the paraffin oil exists in the system in the form of micro-particles;

[0034] S02. Rapidly cool the extruded thick sponge; the polymer skeleton structure formed by HDPE is further solidified under low temperature conditions, and separates from the paraffin oil; in addition, for crystalline substrates, rapid cooling can increase the number of crystal nuclei, reduce the crystallinity and refine the crystal grains, reduce the internal stress of the material, and make the sponge have higher toughness and impact resistance, avoiding the increase in brittleness caused by slow cooling;

[0035] S03. Bi-directional stretching: first longitudinal stretching at 60-90℃, then transverse stretching at 90-120℃; through stretching, the sponge can be thinned, and the micro-holes can be enlarged to meet the set requirements; after the micro-holes are enlarged, additional space is provided for the organic solvent to enter and better remove the paraffin oil during the subsequent removal of paraffin oil;

[0036] S04. Removing paraffin oil: soaking or spraying the stretched sponge with an organic solvent to remove the paraffin oil in the sponge to obtain a sponge for new energy battery separators;

[0037] S05. Drying the sponge to remove residual solvents;

[0038] S06. Heat setting and slitting.

[0039] Preferably, in S02, the sponge is rapidly cooled to 20-40℃.

[0040] Preferably, in S03, the sponge is stretched longitudinally by 2-4 times and transversely by 3-5 times.

[0041] Preferably, in S04, the organic solvent is selected from hexane or dichloromethane.

[0042] Preferably, in S05, the drying temperature is 80-120℃.

[0043] Preferably, in S06, the heat setting temperature is 120-140℃.

[0044] Example 1

[0045] A method for preparing a sponge for new energy battery separators, comprising the following steps:

[0046] S01. Mixing the raw materials for preparing the sponge according to the formula, and feeding them into a screw extruder to melt extrude a 200 micrometer thick sponge at 180-230℃;

[0047] The sponge for new energy battery separators, by weight, is prepared from the following components: 40 parts of HDPE, 57.1 parts of paraffin oil, 0.5 parts of antioxidant, 0.4 parts of lubricant, and 2 parts of toughening agent; the weight average molecular weight of HDPE is 200000-250000g / mol; further comprising 5 parts of modified basalt fiber and 15 parts of modified glass fiber;

[0048] The antioxidant is composed of 0.2 parts of hindered phenolic antioxidant 1010 and 0.3 parts of phosphite antioxidant 168; the lubricant is stearic acid amide; the toughening agent is EVA;

[0049] S02. The extruded sponge is rapidly cooled down to below 40℃ by using cooling roller within 20s;

[0050] S03. Bidirectional stretching: first longitudinal stretching by 3 times at 85℃, then transverse stretching by 5 times at 105℃;

[0051] S04. Removing paraffin oil: the stretched sponge is soaked in organic solvent (hexane) to remove paraffin oil in the sponge, obtaining the sponge;

[0052] S05. Drying the sponge at 95℃ to remove residual solvent;

[0053] S06. Heat setting at 130℃ for 10 minutes, and then cutting.

[0054] Example 2

[0055] A method for preparing a sponge for new energy battery separator, which is different from example 1 in that the formula of the sponge is different, in this embodiment, the sponge for new energy battery separator is prepared from the following components by weight fraction: 44 parts of HDPE, 53.1 parts of paraffin oil, 0.5 parts of antioxidant, 0.4 parts of lubricant, 2 parts of toughening agent; the weight average molecular weight of HDPE is 200000-250000g / mol; further comprising 7 parts of modified basalt fiber and 13 parts of modified glass fiber;

[0056] The antioxidant is composed of 0.2 parts of hindered phenolic antioxidant 1010 and 0.3 parts of phosphite antioxidant 168; the lubricant is stearic acid amide; the toughening agent is EVA.

[0057] Example 3

[0058] A method for preparing a sponge for new energy battery separator, which is different from example 1 in that the formula of the sponge is different, in this embodiment, the toughening agent is POE.

[0059] Example 4

[0060] A method for preparing a sponge for new energy battery separator, which is different from example 1 in that, in this embodiment, the toughening agent is composed of EVA and POE with a mass ratio of 1:1.

[0061] Comparative example 1

[0062] A preparation method of a sponge for new energy battery diaphragm, which is different from example 1 in that the formula of the sponge is different, in the present comparative example, the raw materials for preparing the sponge consist of 36 parts of HDPE, 61.1 parts of paraffin oil, 0.5 parts of antioxidant, 0.4 parts of lubricant, and 2 parts of toughening agent, by weight; the antioxidant consists of 0.2 parts of hindered phenolic antioxidant 1010 and 0.3 parts of phosphite antioxidant 168; the lubricant is stearic acid amide; the toughening agent is EVA; the weight average molecular weight of HDPE is 200000-250000 g / mol; and further comprising 5 parts of modified basalt fiber and 15 parts of modified glass fiber.

[0063] Comparative example 2

[0064] A preparation method of a sponge for new energy battery diaphragm, which is different from example 1 in that the formula of the sponge is different, in the present comparative example, the raw materials for preparing the sponge consist of 48 parts of HDPE, 49.1 parts of paraffin oil, 0.5 parts of antioxidant, 0.4 parts of lubricant, and 2 parts of toughening agent, by weight; the weight average molecular weight of HDPE is 200000-250000 g / mol; and further comprising 5 parts of modified basalt fiber and 15 parts of modified glass fiber; the antioxidant consists of 0.2 parts of hindered phenolic antioxidant 1010 and 0.3 parts of phosphite antioxidant 168; the lubricant is stearic acid amide; and the toughening agent is EVA.

[0065] Comparative example 3

[0066] A preparation method of a sponge for new energy battery diaphragm, which is different from example 1 in that the formula of the sponge is different, in the present comparative example, the raw materials for preparing the sponge consist of:

[0067] The sponge for new energy battery diaphragm, the raw materials for preparing the sponge consist of 40 parts of HDPE, 57.1 parts of paraffin oil, 0.5 parts of antioxidant, and 0.4 parts of lubricant, by weight; the weight average molecular weight of HDPE is 200000-250000 g / mol; and further comprising 20 parts of modified glass fiber; the antioxidant consists of 0.2 parts of hindered phenolic antioxidant 1010 and 0.3 parts of phosphite antioxidant 168; and the lubricant is stearic acid amide.

[0068] Comparative example 4

[0069] A preparation method of a sponge for new energy battery separator, which is different from example 1 in that the formula of the sponge is different, in the present comparative example, the preparation raw materials of the sponge for new energy battery separator consist of 40 parts of HDPE, 57.1 parts of paraffin oil, 0.5 parts of antioxidant, 0.4 parts of lubricant, 2 parts of toughening agent, by weight fraction; the weight average molecular weight of HDPE is 200000-250000g / mol; further comprising 5 parts of modified basalt fiber and 15 parts of modified glass fiber; the antioxidant consists of 0.2 parts of hindered phenolic antioxidant 1010 and 0.3 parts of phosphite antioxidant 168; the lubricant is stearic acid amide.

[0070] Comparative example 5

[0071] A preparation method of a sponge for new energy battery separator, which is different from example 1 in that the formula of the sponge is different, in the present comparative example, the preparation raw materials of the sponge for new energy battery separator consist of 40 parts of HDPE, 57.1 parts of paraffin oil, 0.5 parts of antioxidant, 0.4 parts of lubricant, 2 parts of toughening agent, by weight fraction; the weight average molecular weight of HDPE is 200000-250000g / mol; further comprising 5 parts of modified basalt fiber and 15 parts of modified glass fiber; the antioxidant consists of 0.2 parts of hindered phenolic antioxidant 1010 and 0.3 parts of phosphite antioxidant 168; the lubricant is stearic acid amide.

[0072] The preparation raw materials of the sponge for new energy battery separator consist of 40 parts of HDPE, 57.1 parts of paraffin oil, 0.5 parts of antioxidant, 0.4 parts of lubricant, 2 parts of toughening agent, by weight fraction; the weight average molecular weight of HDPE is 200000-250000g / mol; further comprising 15 parts of modified basalt fiber; the antioxidant consists of 0.2 parts of hindered phenolic antioxidant 1010 and 0.3 parts of phosphite antioxidant 168; the lubricant is stearic acid amide.

[0073] Comparative example 6

[0074] A preparation method of a sponge for new energy battery separator, S01. Mix the preparation raw materials of the sponge according to the formula, put them into the screw extruder, and melt extrude the sponge 500 microns thick under the condition of 180-230℃;

[0075] The preparation raw materials of the sponge for new energy battery separator consist of 40 parts of HDPE, 57.1 parts of paraffin oil, 0.5 parts of antioxidant, 0.4 parts of lubricant, 2 parts of toughening agent, by weight fraction; the weight average molecular weight of HDPE is 200000-250000g / mol; further comprising 5 parts of modified basalt fiber and 15 parts of modified glass fiber; the antioxidant consists of 0.2 parts of hindered phenolic antioxidant 1010 and 0.3 parts of phosphite antioxidant 168; the lubricant is stearic acid amide.

[0076] The antioxidant consists of 0.2 parts of hindered phenolic antioxidant 1010 and 0.3 parts of phosphite antioxidant 168; the lubricant is stearic acid amide; the toughening agent is EVA;

[0077] S02. Cool the extruded sponge to 85℃ by cold air;

[0078] S03. Two-way stretching: first longitudinal stretching by 3 times at 85℃, then transverse stretching by 5 times at 105℃;

[0079] S04. Removing paraffin oil: soaking the sponge after stretching with an organic solvent (hexane) to remove paraffin oil in the sponge, obtaining the sponge;

[0080] S05. Drying the sponge, the temperature of the drying oven is 95℃, to remove residual solvent;

[0081] S06. Heat setting at 130℃ for 10 minutes, and cutting after setting.

[0082] The cut sponge is subjected to nickel plating treatment, and then the properties of the sponge prepared in the above examples and comparative examples are further tested, and the results are as follows:

[0083] Table I

[0084]

[0085] Table II

[0086]

[0087] From the results of Table I and Table II, it can be seen that the sponge prepared in Examples 1-4 meets the design requirements in many aspects. Among them, the comprehensive performance of Example 4 is the best, which shows that the toughening agent composed of EVA and POE with a mass ratio of 1:1 can better improve the performance of the sponge.

[0088] Comparative Example 1 and Example 1 are different in the formula of the sponge, specifically, the amount of HDPE is less and the amount of paraffin oil is more. The test results show that many indicators do not meet the requirements, the reason may be that as a diluent, the high proportion of paraffin oil will cause the droplet volume of the "diluent-rich phase" to increase during phase separation, and the number of HDPE molecular chains is insufficient, which cannot form a dense three-dimensional skeleton through molecular entanglement to constrain the droplet size. In addition, HDPE is the core support of the skeleton, and the insufficient amount will reduce the density and structure of the polymer skeleton after solidification, resulting in insufficient tensile strength.

[0089] Comparative Example 2 and Example 1 are different in the formula of the sponge, specifically, the amount of HDPE is more and the amount of paraffin oil is less. From the results, although the breaking strength and other indicators are improved, the porosity will decrease when the proportion of paraffin oil is too small. The main reason is that paraffin oil is the key to forming pores later, and the insufficient proportion will cause the number and volume of droplets in the "diluent-rich phase" to decrease during phase separation, and the number and size of pores left after extraction are small, resulting in low porosity and poor air permeability.

[0090] Comparative Example 3 and Example 1, only additional modified glass fiber, without the use of toughening agent and modified basalt fiber, can be seen that the tensile strength is significantly decreased. The rigidity of modified basalt fiber can enhance the skeleton support, and the toughening agent (EVA or POE) can improve the brittleness of HDPE by molecular chain toughening. Without the two, the system can not effectively improve the toughness of HDPE itself by relying on the modified glass fiber.

[0091] Comparative Example 4 and Example 1, without adding a toughening agent, its tensile strength is better than Comparative Example 3, but still not as good as Example 1. Modified glass fiber and basalt fiber can improve the skeleton strength through their own rigidity or dispersibility, but both are inorganic fibers, which cannot relieve the brittleness of HDPE like organic toughening agent through molecular chain insertion and interface toughening.

[0092] Comparative Example 5 and Example 1, a large amount of modified basalt fiber is used for modification, and its comprehensive performance is slightly worse than Example 1. This is because basalt fiber is strong and easy to agglomerate, and when the amount is large, even after modification, local fiber aggregation may still occur, affecting the air permeability. In the scheme of Example 1, by adding an appropriate amount of modified glass fiber and toughening agent, a part of the modified basalt fiber can be replaced, and the comprehensive performance can be improved to a certain extent, which can reduce the use of modified basalt fiber and reduce the cost.

[0093] Comparative Example 6 and Example 1, after extrusion, the temperature is not quickly reduced to low temperature, but is reduced to the stretching temperature, and directly enters the stretching, and the performance of the sponge prepared is lower than that of Example 1. The main reason is that rapid cooling is to make the HDPE molecular chain crystallize quickly to form fine and uniform crystal structure and improve the skeleton toughness; and slow cooling to the stretching temperature can make the HDPE crystal grow fully to form coarse spherulites, and the bonding force between the spherulites is weak, which leads to the increase of the skeleton brittleness and the decrease of the tensile strength.

[0094] The sponge of the application has certain mechanical toughness, which can disperse and bear the pressure of the diaphragm as a support structure, and the porous structure and elasticity of the sponge can fill the micro gaps between the diaphragm and the electrode, so that the diaphragm is tightly attached to the surface of the electrode through physical extrusion, reducing the interface impedance. In addition, the sponge support skeleton can also actively absorb the stress generated by the expansion of the electrode to avoid the diaphragm from being over-extruded and failing. After being plated with nickel, the sponge still has good air permeability, which meets the design requirements.

[0095] It can be understood that for those skilled in the art, equivalent replacement or change can be made according to the technical scheme and inventive concept of the application, and all these changes or replacements shall belong to the protection scope of the appended claims of the application.

Claims

1. A sponge for use in separators of new energy batteries, characterized in that, The raw materials for its preparation, by weight, include the following components: 40-45 parts HDPE, 53-58 parts paraffin oil, 0.15-0.8 parts antioxidant, 0.05-0.5 parts lubricant, and 1-3 parts toughening agent; the HDPE has a weight-average molecular weight of 200,000-250,000 g / mol; it also includes 5-7 parts modified basalt fiber and 13-15 parts modified glass fiber; the modified basalt fiber has a thickness of 3-5 micrometers and is modified by soaking in a 2 wt% silane coupling agent solution for 1 hour; the modified glass fiber is modified by soaking in a 2 wt% silane coupling agent solution for 1 hour.

2. The sponge for new energy battery separators according to claim 1, characterized in that, The antioxidants include hindered phenolic antioxidants and phosphorous acid antioxidants.

3. The sponge for new energy battery separators according to claim 1, characterized in that, The lubricant includes one or both of stearamide and erucamide.

4. The sponge for new energy battery separators according to claim 1, characterized in that, The toughening agent includes one or both of EVA and POE.

5. A method for preparing a sponge for use in new energy battery separators, characterized in that, The method for preparing the sponge for use in new energy battery separators as described in any one of claims 1-4 comprises the following steps: S01. Mix the raw materials for sponge preparation according to the formula, put them into a screw extruder, and perform melt extrusion at 180-230℃; S02. Rapidly cool down the extruded sponge; S03. Biaxial stretching: first, longitudinal stretching is performed at 60-90℃, and then transverse stretching is performed at 90-120℃; S04. Removal of paraffin oil: The sponge is soaked or sprayed with an organic solvent to remove the paraffin oil from the sponge, thus obtaining a sponge for use in new energy battery separators. S05. Dry the sponge to remove residual solvent; S06. Heat setting and slitting.

6. The method for preparing the sponge for a new energy battery separator according to claim 5, characterized in that, In step S02, the sponge is rapidly cooled to 20–40°C.

7. The method for preparing the sponge for a new energy battery separator according to claim 5, characterized in that, In S03, the sponge is stretched 2 to 4 times longitudinally and 3 to 5 times laterally.

8. The method for preparing the sponge for a new energy battery separator according to claim 5, characterized in that, In the SO4, the organic solvent is selected from hexane or dichloromethane.

9. The method for preparing the sponge for a new energy battery separator according to claim 5, characterized in that, In S05, the drying temperature is 80–120°C.

10. The method for preparing the sponge for a new energy battery separator according to claim 5, characterized in that, In S06, the heat setting temperature is 120–140°C.

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