Nonwoven fabric for solid electrolyte support layer, and method of manufacturing and use thereof

Abstract

The present application relates to the technical field of non-woven fabrics, and particularly relates to a non-woven fabric for a solid-state electrolyte support layer, a preparation method and application, the preparation method being: shortening island fibers to obtain pretreated island fibers; slushing the pretreated island fibers in water to obtain a slurry; forming a fiber web through wet papermaking; performing water jetting on the fiber web to obtain a formed island fiber water jet non-woven fabric; performing alkali reduction and fiber opening on the island fiber water jet non-woven fabric; drying the island fiber water jet non-woven fabric after the fiber opening treatment; and winding and slitting the island fiber water jet non-woven fabric after the drying through a roller to obtain the non-woven fabric for the solid-state electrolyte support layer. The non-woven fabric has an extremely thin thickness, excellent porosity and mechanical properties, can improve the strength of the solid-state electrolyte, and is helpful to improve the performance of the all-solid-state electrolyte.

Description

Technical Field

[0001] The invention relates to a non-woven fabric for a solid electrolyte support layer, a preparation method and an application thereof, and belongs to the technical field of non-woven fabrics. Background Art

[0002] With the increasing shortage of fossil energy and the increasing environmental pollution caused by fossil fuel combustion, the development of lithium-ion batteries has become a popular direction for alleviating energy shortages. Traditional liquid batteries have excellent energy density, long cycle life, high voltage, and a wide chemical window, but they also have a series of safety issues. During shock or charge and discharge, the formation of lithium dendrites can damage the battery separator, increasing the risk of battery short circuit and explosion.

[0003] By combining solid electrolytes with lithium metal negative electrodes, higher energy density can be achieved. Compared with traditional liquid electrolytes, the use of solid electrolytes can effectively slow down the growth of lithium dendrites and reduce safety hazards during use. Polymer solid electrolytes are becoming increasingly popular in the battery field due to their high solubility, easy preparation and low cost. However, the mechanical strength of polymer solid electrolytes themselves is insufficient, making it difficult to achieve large-scale production and application, and when they are thin, they are not enough to inhibit the growth of lithium dendrites. Therefore, the solid electrolyte layers currently used are often thick, which is not conducive to achieving higher energy density. In order to solve the problem of poor mechanical strength of solid electrolytes in thin cases, it is necessary to introduce a supporting layer material that is light, flexible, porous, easy to process and has excellent mechanical properties into the solid electrolyte layer.

[0004] Patent application number CN119764597A discloses a solid-state battery processing method, wherein a printed inner frame and a printed outer frame are placed on a solid electrolyte layer, the outer edge of the printed inner frame is located in the area to be processed, and a glue coating area is formed between the outer edge of the printed inner frame and the inner edge of the printed outer frame, and the glue coating area is set to a second preset width, which is smaller than the first preset width; glue is injected into the glue coating area so that the glue forms a support after curing. Using cured glue as a support makes the battery assembly and preparation process more complicated, and it is easy to cause high internal resistance of the battery and low energy efficiency. Patent application number CN119695257A discloses a solid electrolyte film and its preparation method, and a lithium-ion battery, which uses a base film to support the solid electrolyte, wherein the base film is a polyethylene film (PE) or a polypropylene film (PP). However, when these base films are used in batteries, the base film needs to be modified, otherwise the ionic conductivity will be significantly insufficient. Therefore, the application process of using base films of this material as supports in batteries is relatively complicated.

[0005] Therefore, it is of great value for us to develop a thin, high-strength, porous solid electrolyte support layer to improve the mechanical strength of the solid electrolyte and achieve high energy density, high safety and large-scale industrial production of solid-state batteries. Summary of the Invention

[0006] In response to the deficiencies in the prior art, the present invention provides a non-woven fabric for a solid electrolyte support layer, a preparation method, and an application thereof. The non-woven fabric has an extremely thin thickness, excellent porosity, and mechanical properties, can improve the strength of the solid electrolyte, and contribute to improving the performance of the all-solid-state electrolyte. Moreover, as a solid electrolyte support layer, it can enable solid-state batteries to achieve a roll-to-roll production process, thereby facilitating improved performance and production efficiency of solid-state batteries and realizing industrialized and expanded production of solid-state batteries.

[0007] The technical solution of the present invention to solve the above technical problems is as follows: a method for preparing a non-woven fabric for a solid electrolyte support layer, the preparation method comprising:

[0008] S1, chopping the island-in-the-sea fibers to obtain pretreated island-in-the-sea fibers;

[0009] S2: disintegrating the pretreated island fiber in water to obtain a slurry;

[0010] S3: wet-papering the slurry to form a fiber web;

[0011] S4: hydroentangle the fiber web to obtain a formed sea-island fiber hydroentangled nonwoven fabric;

[0012] S5: alkali reduction and fiber opening of sea-island fiber spunlace nonwoven fabric;

[0013] S6: drying the sea-island fiber spunlace nonwoven fabric after the fiber opening treatment;

[0014] S7: The dried sea-island fiber spunlace nonwoven fabric is passed through a roller, rolled up, and cut into pieces to obtain a nonwoven fabric for a solid electrolyte support layer.

[0015] Furthermore, in step S1, the components of the sea-island fiber are PET and COPET, wherein the mass ratio of PET to COPET is (3:7)-(7:3).

[0016] Furthermore, in step S1, the diameter of the island-in-the-sea fibers is 15-25 μm, and the length of the chopped island-in-the-sea fibers is 4-6 mm.

[0017] Furthermore, in step S2, a dispersant and a defoaming agent are added during the decomposition operation;

[0018] The dispersant is at least one of carboxymethyl cellulose, polyethylene oxide, and sodium lauryl sulfate;

[0019] The defoaming agent is at least one of a polyether defoaming agent and a silicone defoaming agent.

[0020] Furthermore, in the slurry, the mass content of the pretreated sea-island fibers is 0.05-0.10%; the mass content of the dispersant is 0.01-0.1%; and the mass content of the defoaming agent is 0.01-0.1%.

[0021] Furthermore, in step S4, the spunlace pressure is 30-40 bar, the spunlace curtain running speed is 70-80 m / min, and the weight of the sea-island fiber spunlace nonwoven fabric is 16-32 g / m 2 .

[0022] Furthermore, in step S5, during the alkali weight reduction and fiber opening treatment, the weight reduction solution used is a NaOH solution, the concentration of the NaOH solution is 5-12 g / L, the temperature during the alkali weight reduction and fiber opening treatment is 90-100° C., and the time is 30-90 min; after the alkali weight reduction and fiber opening treatment, the fiber diameter of the sea-island fiber spunlace nonwoven fabric is 0.8-4 μm;

[0023] In step S6, after drying, the weight of the sea island fiber spunlace nonwoven fabric after fiber opening treatment is 8-20 g / m 2 .

[0024] Furthermore, in step S7, the pressure of the roller is 10-30 MPa, the rotation speed is 8-12 rpm, and the temperature is room temperature.

[0025] The present invention also discloses a non-woven fabric for a solid electrolyte support layer, wherein the non-woven fabric is prepared according to the preparation method of the present invention;

[0026] The nonwoven fabric has a grammage of 8-16 g / m 2 , thickness does not exceed 30µm, porosity is 40%-80%; longitudinal and transverse tensile strength is above 3N / 15mm.

[0027] The present invention also discloses an application of a non-woven fabric for a solid electrolyte supporting layer. The non-woven fabric is applied as a solid electrolyte supporting layer in a battery.

[0028] The beneficial effects of the present invention are:

[0029] The present invention proposes a method for preparing a light, thin, high-strength, porous ultrafine fiber nonwoven fabric that can be used as a solid electrolyte support layer. The use of sea-island fiber wet-laid web can make the product have better isotropy, more uniform mechanical strength in the longitudinal and transverse directions, higher puncture and tear resistance, and high production efficiency, making it more suitable for large-scale industrial applications.

[0030] In the preparation method described in the present invention, the sea island fiber spunlace nonwoven fabric obtained by combining spunlace solid mesh and alkali reduction has a porous small pore structure, which can have excellent mechanical properties while maintaining a large porosity, and under the action of the cold pressing roller, the nonwoven fabric has an extremely low thickness. As a solid electrolyte support layer, it ensures the thinning of the solid electrolyte, effectively improves the battery energy density, reduces the ion conductivity requirements, improves the mechanical properties of the solid electrolyte, and realizes the electromagnetic roll-to-roll production process to adapt to the large-scale and mass production of solid-state batteries.

[0031] More specifically, the preparation method described herein produces an extremely fine fiber diameter after opening of the island-in-the-sea fiber spunlace nonwoven fabric, meeting the requirements for a porous support layer. This increases inter-fiber entanglement and cohesion, resulting in excellent mechanical properties. Wet-laid papermaking, a method for forming nonwoven webs, offers the advantages of high production speed, low web weight, and excellent fiber uniformity. This results in a low weight after forming the nonwoven fabric, thus enabling the lightweight and thin production of island-in-the-sea fiber spunlace nonwoven fabric. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is an SEM image of the nonwoven fabric before alkali weight reduction and fiber opening in Example 1;

[0033] Figure 2 This is the SEM image of the nonwoven fabric after alkali weight reduction and fiber opening in Example 1. DETAILED DESCRIPTION

[0034] The present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used are only for describing specific embodiments and are not intended to limit the present invention.

[0036] A method for preparing a nonwoven fabric for a solid electrolyte support layer, the preparation method comprising:

[0037] S1, chopping the island-in-the-sea fibers to obtain pretreated island-in-the-sea fibers;

[0038] S2: disintegrating the pretreated island fiber in water to obtain a slurry;

[0039] S3: The slurry is formed into a fiber web by means of a downstream screen;

[0040] S4: The formed fiber web is conveyed to a spunlace unit for spunlace, wherein high-pressure water needles pierce the fiber web, causing the fibers of the fiber web to entangle and reinforce each other, thereby obtaining a formed sea-island fiber spunlace nonwoven fabric;

[0041] S5: alkali reduction and fiber opening of sea-island fiber spunlace nonwoven fabric;

[0042] S6: hot air drying the sea-island fiber spunlace nonwoven fabric after the fiber opening treatment;

[0043] S7: The dried sea-island fiber spunlace nonwoven fabric is passed through a roller, rolled up, and cut into pieces to obtain a nonwoven fabric for a solid electrolyte support layer.

[0044] Specifically, in step S1, the components of the sea-island fiber are PET and COPET, the total mass of PET and COPET is 10 parts, and the mass ratio of PET to COPET is (3:7)-(7:3).

[0045] Preferably, in step S1, the components of the sea-island fibers are PET and COPET, wherein the mass ratio of PET to COPET is 5:5.

[0046] More specifically, the preparation method of the sea island fiber is as follows: PET and COPET polymer chips are used as raw materials, which are dried and then respectively extruded into different screw extruders for melting (melting temperature: PET: 285-290°C, COPET: 275-280°C). After filtering and metering, they enter the spinning box (280°C) and are extruded from the spinneret. Finally, they undergo side-blown cooling and tubular drawing processes to obtain PET / COPET sea island fibers with a polymer component ratio of (3:7) to (7:3). The drawing pressure is set to 5.5 bar.

[0047] More specifically, the PET chips used in the embodiments of the present invention were purchased from Wankai New Materials Co., Ltd. (model WK-881), and the COPET chips were purchased from Yangzhou Tianlun Fiber Co., Ltd. However, this does not constitute a limitation to the technical solution of the present invention.

[0048] Specifically, in step S1, the diameter of the island-in-the-sea fibers is 15-25 μm, and the length of the chopped island-in-the-sea fibers is 4-6 mm.

[0049] Preferably, the length of the chopped sea-island fibers is 5 mm.

[0050] Specifically, in step S2, the pretreated sea-island fibers are added with water and stirred, a dispersant and a defoamer are added, and then pumped into a deflaking machine for deflaking, and then prepared into a slurry according to demand after deflaking;

[0051] The dispersant is at least one of carboxymethyl cellulose, polyethylene oxide, and sodium lauryl sulfate;

[0052] The defoaming agent is at least one of a polyether defoaming agent and a silicone defoaming agent.

[0053] Specifically, in the slurry, the mass content of the pretreated sea-island fibers is 0.05-0.10%; the mass content of the dispersant is 0.01-0.1%; and the mass content of the defoaming agent is 0.01-0.1%.

[0054] Specifically, in step S4, the spunlace pressure is 30-40 bar, the spunlace curtain running speed is 70-80 m / min, and the weight of the sea-island fiber spunlace nonwoven fabric is 16-32 g / m 2 (Weight after drying).

[0055] Preferably, in step S4, the water spunlace pressure is 35 bar, and the water spunlace mesh curtain running speed is 75 m / min.

[0056] Specifically, in step S5, during the alkali weight reduction and fiber opening treatment, the weight reduction solution used is a NaOH solution, the concentration of the NaOH solution is 5-12 g / L, the temperature during the alkali weight reduction and fiber opening treatment is 90-100 ° C, the time is 30-90 min, and the fiber diameter of the sea island fiber spunlace nonwoven fabric after the alkali weight reduction and fiber opening treatment is 0.8-4 µm (the diameter of the fiber in the nonwoven fabric is observed by SEM).

[0057] Preferably, when the concentration of the NaOH solution is relatively high, a relatively short alkali weight reduction and fiber opening treatment time is used; when the concentration of the NaOH solution is relatively low, a relatively long alkali weight reduction and fiber opening treatment time is used.

[0058] Specifically, in step S6, after drying, the weight of the sea island fiber spunlace nonwoven fabric after fiber opening treatment is 8-20 g / m 2 .

[0059] More specifically, in step S6, the hot air penetration drying method is used, the temperature is 130°C, the time is 60 seconds, and the vehicle speed is 50 m / min.

[0060] Specifically, in step S7, the pressure of the roller is 10-30 MPa, the rotation speed is 8-12 rpm, and the temperature is room temperature.

[0061] The present invention also discloses a non-woven fabric for a solid electrolyte support layer, wherein the non-woven fabric is prepared according to the preparation method of the present invention;

[0062] The nonwoven fabric has a grammage of 8-16 g / m 2 , thickness does not exceed 30µm, porosity is 40%-80%; longitudinal and transverse tensile strength is above 3N / 15mm.

[0063] More specifically, the nonwoven fabric has a gram weight of 10-15 g / m 2 , thickness is 5-25µm, porosity is 50%-75%, longitudinal tensile strength is above 5N / 15mm, and transverse tensile strength is above 5N / 15mm.

[0064] Preferably, the nonwoven fabric has a gram weight of 13-14 g / m 2 , thickness is 10-20µm, porosity is 55%-70%, longitudinal tensile strength is above 7N / 15mm, and transverse tensile strength is above 7N / 15mm.

[0065] The present invention also discloses the use of a nonwoven fabric for a solid electrolyte support layer, which is used as a solid electrolyte support layer in a battery. During use, a solid electrolyte slurry is applied to both surfaces of the solid electrolyte support layer using a coating machine and then dried to produce a flexible, lightweight, high-porosity, and excellent mechanical strength solid electrolyte.

[0066] Example 1

[0067] A method for preparing a nonwoven fabric for a solid electrolyte support layer, the preparation method comprising:

[0068] (1) PET / COPET island fibers (mass ratio of PET to COPET is 5:5) are chopped to obtain pretreated island fibers; the length of the chopped island fibers is 5 mm and the diameter of the island fibers is 25 μm;

[0069] (2) The pretreated island fiber was stirred with water (the mass content of the island fiber was 0.05 wt%), and 0.01% of a carboxymethyl cellulose dispersant (purchased from Langfang Yuxiu Technology Co., Ltd.) and 0.01% of a polyether defoamer (purchased from Yantai Hengxin Chemical Technology Co., Ltd., THIX-276) were added. The mixture was then pumped into a deflaking machine for deflaking. After deflaking, the mixture was prepared into a slurry according to the requirements.

[0070] (3) The mixed slurry is wet-laid by a downstream method to form a sea-island fiber web;

[0071] (4) The formed fiber web is transported to the hydroentanglement unit for hydroentanglement, wherein the high-pressure water needle punctures the fiber web so that the fibers therein are entangled and reinforced with each other. The process conditions are: hydroentanglement pressure of 35 MPa, hydroentanglement curtain running speed of 75 m / min, and the weight is 16 g / m 2 Sea-island fiber spunlace nonwoven fabric (weight after drying, the same below);

[0072] (5) The sea island fiber spunlace nonwoven fabric was subjected to alkali reduction and fiber opening. The process conditions were: NaOH solution concentration of 12 g / L, temperature of 90 °C, time of 30 minutes, and the weight of the sea island fiber spunlace nonwoven fabric after fiber opening was 8 g / m 2 (All are weights after drying, the same below), the fiber diameter of the nonwoven fabric after opening is 4µm;

[0073] (6) The sea island fiber spunlace nonwoven fabric after fiber opening treatment was subjected to hot air drying under the following drying conditions: temperature 130°C, time 60 seconds, and speed 50 m / min;

[0074] (7) The dried sea island fiber spunlace nonwoven fabric is passed through a normal temperature roller with the process conditions of pressure of 10 MPa and rotation speed of 10 rpm to obtain a light, high-strength, porous ultrafine fiber nonwoven fabric that can be used as a solid electrolyte support layer.

[0075] Example 2

[0076] A method for preparing a nonwoven fabric for a solid electrolyte support layer, the preparation method comprising:

[0077] (1) PET / COPET island fibers (mass ratio of PET to COPET is 5:5) are chopped to obtain pretreated island fibers; the length of the chopped island fibers is 5 mm and the diameter of the island fibers is 22 μm;

[0078] (2) The pretreated sea island fibers were stirred with water (the mass content of sea island fibers was 0.05 wt%), 0.01% sodium lauryl sulfate dispersant (purchased from Zibo Jujin Chemical Co., Ltd.) and 0.01% organosilicon defoamer (purchased from Foshan Nanhai Datian Chemical Co., Ltd., AT-889) were added, and then pumped into a deflaking machine for deflaking. After deflaking, the slurry was prepared according to the demand;

[0079] (3) The mixed slurry is wet-laid by a downstream method to form a sea-island fiber web;

[0080] (4) The formed fiber web is transported to the hydroentanglement unit for hydroentanglement, wherein the high-pressure water needle punctures the fiber web so that the fibers therein are entangled and reinforced with each other. The process conditions are: hydroentanglement pressure of 35 MPa, hydroentanglement curtain running speed of 75 m / min, and the weight is 16 g / m 2 Sea-island fiber spunlace nonwoven fabric;

[0081] (5) The sea island fiber spunlace nonwoven fabric was subjected to alkali reduction and fiber opening. The process conditions were: NaOH solution concentration of 10 g / L, temperature of 100 °C, time of 75 minutes, and the weight of the sea island fiber spunlace nonwoven fabric after fiber opening was 8 g / m 2, the fiber diameter of the nonwoven fabric after fiber opening is 3µm;

[0082] (6) The sea island fiber spunlace nonwoven fabric after fiber opening treatment was subjected to hot air drying under the following drying conditions: temperature 130°C, time 60 seconds, and speed 50 m / min;

[0083] (7) The dried sea island fiber spunlace nonwoven fabric is passed through a normal temperature roller with the process conditions of pressure of 20 MPa and rotation speed of 10 rpm to obtain a light, high-strength, porous ultrafine fiber nonwoven fabric that can be used as a solid electrolyte support layer.

[0084] Example 3

[0085] A method for preparing a nonwoven fabric for a solid electrolyte support layer, the preparation method comprising:

[0086] (1) PET / COPET island fibers (mass ratio of PET to COPET is 5:5) are chopped to obtain pretreated island fibers; the length of the chopped island fibers is 5 mm and the diameter of the island fibers is 18 μm;

[0087] (2) The pretreated sea island fiber is stirred with water (the mass content of the sea island fiber is 0.05 wt%), 0.1% of carboxymethyl cellulose dispersant and 0.1% of polyether defoamer are added, and then pumped into a deflaking machine for deflaking. After deflaking, the slurry is prepared according to the demand;

[0088] (3) The mixed slurry is wet-laid by a downstream method to form a sea-island fiber web;

[0089] (4) The formed fiber web is transported to the hydroentanglement unit for hydroentanglement, wherein the high-pressure water needle punctures the fiber web so that the fibers therein are entangled and reinforced with each other. The process conditions are: hydroentanglement pressure of 35 MPa, hydroentanglement curtain running speed of 75 m / min, and the weight is 16 g / m 2 The diameter of the fiber in the sea-island fiber spunlace nonwoven fabric after opening is 1µm;

[0090] (5) The sea island fiber spunlace nonwoven fabric was subjected to alkali reduction and fiber opening. The process conditions were: NaOH solution concentration of 12 g / L, temperature of 100 °C, and time of 90 minutes. The weight of the sea island fiber spunlace nonwoven fabric after fiber opening was 8 g / m 2 ;

[0091] (6) The sea island fiber spunlace nonwoven fabric after fiber opening treatment was subjected to hot air drying under the following drying conditions: temperature 130°C, time 60 seconds, and speed 50 m / min;

[0092] (7) The dried sea island fiber spunlace nonwoven fabric is passed through a normal temperature roller with the process conditions of pressure of 30 MPa and rotation speed of 10 rpm to obtain a light, high-strength, porous ultrafine fiber nonwoven fabric that can be used as a solid electrolyte support layer.

[0093] Example 4

[0094] A method for preparing a nonwoven fabric for a solid electrolyte support layer, the preparation method comprising:

[0095] (1) PET / COPET island fibers (mass ratio of PET to COPET is 5:5) are chopped to obtain pretreated island fibers; the length of the chopped island fibers is 5 mm and the diameter of the island fibers is 15 μm;

[0096] (2) The pretreated island fiber was stirred with water (the mass content of the island fiber was 0.05 wt%), 0.01% of polyethylene oxide dispersant (purchased from Jilin Xingyun Chemical Co., Ltd., Jilin Chemical Group) and 0.01% of silicone defoamer were added, and then pumped into a deflaking machine for deflaking. After deflaking, the slurry was prepared according to the demand;

[0097] (3) The mixed slurry is wet-laid by a downstream method to form a sea-island fiber web;

[0098] (4) The formed fiber web is transported to the hydroentanglement unit for hydroentanglement, wherein the high-pressure water needle punctures the fiber web so that the fibers therein are entangled and reinforced with each other. The process conditions are: hydroentanglement pressure of 35 MPa, hydroentanglement curtain running speed of 75 m / min, and the weight is 16 g / m 2 Sea-island fiber spunlace nonwoven fabric;

[0099] (5) The sea island fiber spunlace nonwoven fabric was subjected to alkali reduction and fiber opening. The process conditions were: NaOH solution concentration of 5 g / L, temperature of 100 °C, time of 90 minutes, and the weight of the sea island fiber spunlace nonwoven fabric after fiber opening was 8 g / m 2 , the fiber diameter of the nonwoven fabric after fiber opening is 0.8µm;

[0100] (6) The sea island fiber spunlace nonwoven fabric after fiber opening treatment was subjected to hot air drying under the following drying conditions: temperature 130°C, time 60 seconds, and speed 50 m / min;

[0101] (7) The dried sea island fiber spunlace nonwoven fabric is passed through a normal temperature roller with the process conditions of pressure of 10 MPa and rotation speed of 10 rpm to obtain a light, high-strength, porous ultrafine fiber nonwoven fabric that can be used as a solid electrolyte support layer.

[0102] Example 5

[0103] A method for preparing a nonwoven fabric for a solid electrolyte support layer, the preparation method comprising:

[0104] (1) PET / COPET island fibers (mass ratio of PET to COPET is 5:5) are chopped to obtain pretreated island fibers; the length of the chopped island fibers is 5 mm and the diameter of the island fibers is 15 μm;

[0105] (2) The pretreated sea island fiber is stirred with water (the mass content of the sea island fiber is 0.05 wt%), 0.01% of carboxymethyl cellulose dispersant and 0.01% of polyether defoamer are added, and then pumped into a deflaking machine for deflaking. After deflaking, the slurry is prepared according to the demand;

[0106] (3) The mixed slurry is wet-laid by a downstream method to form a sea-island fiber web;

[0107] (4) The formed fiber web is transported to the hydroentanglement unit for hydroentanglement, wherein the high-pressure water needle punctures the fiber web so that the fibers therein are entangled and reinforced with each other. The process conditions are: hydroentanglement pressure of 35 MPa, hydroentanglement curtain running speed of 75 m / min, and the weight is 16 g / m 2 Sea-island fiber spunlace nonwoven fabric;

[0108] (5) The sea island fiber spunlace nonwoven fabric was subjected to alkali reduction and fiber opening. The process conditions were: NaOH solution concentration of 10 g / L, temperature of 100 °C, and time of 90 minutes. The weight of the sea island fiber spunlace nonwoven fabric after fiber opening was 8 g / m 2 , the fiber diameter of the nonwoven fabric after fiber opening is 0.8µm;

[0109] (6) The sea island fiber spunlace nonwoven fabric after fiber opening treatment was subjected to hot air drying under the following drying conditions: temperature 130°C, time 60 seconds, and speed 50 m / min;

[0110] (7) The dried sea island fiber spunlace nonwoven fabric is passed through a normal temperature roller with the process conditions of pressure of 20 MPa and rotation speed of 10 rpm to obtain a light, high-strength, porous ultrafine fiber nonwoven fabric that can be used as a solid electrolyte support layer.

[0111] Example 6

[0112] A method for preparing a nonwoven fabric for a solid electrolyte support layer, the preparation method comprising:

[0113] (1) PET / COPET island fibers (mass ratio of PET to COPET is 5:5) are chopped to obtain pretreated island fibers; the length of the chopped island fibers is 5 mm and the diameter of the island fibers is 25 μm;

[0114] (2) The pretreated sea island fibers were stirred with water (sea island fiber mass content 0.1 wt%), and 0.01% by mass of carboxymethyl cellulose dispersant and 0.01% by mass of polyether defoamer were added, and then pumped into a deflaking machine for deflaking. After deflaking, the slurry was prepared according to the demand;

[0115] (3) The mixed slurry is wet-laid by a downstream method to form a sea-island fiber web;

[0116] (4) The formed fiber web is transported to the spunlace unit for spunlace, wherein the high-pressure water needle punctures the fiber web so that the fibers therein are entangled and reinforced with each other. The process conditions are: the spunlace pressure is 35 MPa, the spunlace curtain running speed is 75 m / min, and the gram weight is 32 g / m 2 Sea-island fiber spunlace nonwoven fabric;

[0117] (5) The sea island fiber spunlace nonwoven fabric was subjected to alkali reduction and fiber opening. The process conditions were: NaOH solution concentration of 12 g / L, temperature of 90 °C, time of 30 minutes, and the weight of the sea island fiber spunlace nonwoven fabric after fiber opening was 16 g / m 2 , the fiber diameter of the nonwoven fabric after fiber opening is 4µm;

[0118] (6) The sea island fiber spunlace nonwoven fabric after fiber opening treatment was subjected to hot air drying under the following drying conditions: temperature 130°C, time 60 seconds, and speed 50 m / min;

[0119] (7) The dried sea island fiber spunlace nonwoven fabric is passed through a normal temperature roller with the process conditions of pressure of 10 MPa and rotation speed of 10 rpm to obtain a light, high-strength, porous ultrafine fiber nonwoven fabric that can be used as a solid electrolyte support layer.

[0120] Example 7

[0121] A method for preparing a nonwoven fabric for a solid electrolyte support layer, the preparation method comprising:

[0122] (1) PET / COPET island fibers (mass ratio of PET to COPET is 5:5) are chopped to obtain pretreated island fibers; the length of the chopped island fibers is 5 mm and the diameter of the island fibers is 22 μm;

[0123] (2) The pretreated sea island fiber is stirred with water (the mass content of the sea island fiber is 0.1 wt%), 0.01% of sodium lauryl sulfate dispersant and 0.01% of silicone defoamer are added, and then pumped into a deflaking machine for deflaking. After deflaking, the slurry is prepared according to the demand;

[0124] (3) The mixed slurry is wet-laid by a downstream method to form a sea-island fiber web;

[0125] (4) The formed fiber web is transported to the spunlace unit for spunlace, wherein the high-pressure water needle punctures the fiber web so that the fibers therein are entangled and reinforced with each other. The process conditions are: the spunlace pressure is 35 MPa, the spunlace curtain running speed is 75 m / min, and the gram weight is 32 g / m 2 Sea-island fiber spunlace nonwoven fabric;

[0126] (5) The sea island fiber spunlace nonwoven fabric was subjected to alkali reduction and fiber opening. The process conditions were: NaOH solution concentration of 10 g / L, temperature of 100 °C, and time of 75 minutes. The weight of the sea island fiber spunlace nonwoven fabric after fiber opening was 16 g / m 2 , the fiber diameter of the nonwoven fabric after fiber opening is 3µm;

[0127] (6) The sea island fiber spunlace nonwoven fabric after fiber opening treatment was subjected to hot air drying under the following drying conditions: temperature 130°C, time 60 seconds, and speed 50 m / min;

[0128] (7) The dried sea island fiber spunlace nonwoven fabric is passed through a normal temperature roller with the process conditions of pressure of 20 MPa and rotation speed of 10 rpm to obtain a light, high-strength, porous ultrafine fiber nonwoven fabric that can be used as a solid electrolyte support layer.

[0129] Example 8

[0130] A method for preparing a nonwoven fabric for a solid electrolyte support layer, the preparation method comprising:

[0131] (1) PET / COPET island fibers (mass ratio of PET to COPET is 3:7) were chopped to obtain pretreated island fibers; the length of the chopped island fibers was 4 mm and the diameter of the island fibers was 22 μm;

[0132] (2) The pretreated sea island fiber is stirred with water (the mass content of the sea island fiber is 0.07 wt%), 0.02% of sodium lauryl sulfate dispersant and 0.03% of silicone defoamer are added, and then pumped into a deflaking machine for deflaking. After deflaking, the slurry is prepared according to the demand;

[0133] (3) The mixed slurry is wet-laid by a downstream method to form a sea-island fiber web;

[0134] (4) The formed fiber web is transported to the hydroentanglement unit for hydroentanglement, wherein the high-pressure water needle punctures the fiber web so that the fibers therein are entangled and reinforced with each other. The process conditions are: hydroentanglement pressure of 30 MPa, hydroentanglement curtain running speed of 70 m / min, and the weight is 17 g / m2 Sea-island fiber spunlace nonwoven fabric;

[0135] (5) The sea island fiber spunlace nonwoven fabric was subjected to alkali reduction and fiber opening. The process conditions were: NaOH solution concentration of 10 g / L, temperature of 100 °C, time of 80 minutes, and the weight of the sea island fiber spunlace nonwoven fabric after fiber opening was 8 g / m 2 , the fiber diameter of the nonwoven fabric after fiber opening is 3µm;

[0136] (6) The sea island fiber spunlace nonwoven fabric after fiber opening treatment was subjected to hot air drying under the following drying conditions: temperature 130°C, time 60 seconds, and speed 50 m / min;

[0137] (7) The dried sea island fiber spunlace nonwoven fabric is passed through a normal temperature roller with the process conditions of pressure of 25 MPa and rotation speed of 9 rpm to obtain a light, high-strength, porous ultrafine fiber nonwoven fabric that can be used as a solid electrolyte support layer.

[0138] Example 9

[0139] A method for preparing a nonwoven fabric for a solid electrolyte support layer, the preparation method comprising:

[0140] (1) PET / COPET island fibers (mass ratio of PET to COPET is 7:3) are chopped to obtain pretreated island fibers; the length of the chopped island fibers is 6 mm and the diameter of the island fibers is 20 μm;

[0141] (2) The pretreated sea island fiber is stirred with water (the mass content of the sea island fiber is 0.05 wt%), 0.02% of sodium lauryl sulfate dispersant and 0.02% of silicone defoamer are added, and then pumped into a deflaking machine for deflaking. After deflaking, the slurry is prepared according to the demand;

[0142] (3) The mixed slurry is wet-laid by a downstream method to form a sea-island fiber web;

[0143] (4) The formed fiber web is transported to the spunlace unit for spunlace, wherein the high-pressure water needle punctures the fiber web so that the fibers therein are entangled and reinforced with each other. The process conditions are: the spunlace pressure is 40 MPa, the spunlace curtain running speed is 80 m / min, and the gram weight is 18 g / m 2 Sea-island fiber spunlace nonwoven fabric;

[0144] (5) The sea island fiber spunlace nonwoven fabric was subjected to alkali reduction and fiber opening. The process conditions were: NaOH solution concentration of 10 g / L, temperature of 100 °C, time of 70 minutes, and the weight of the sea island fiber spunlace nonwoven fabric after fiber opening was 8 g / m 2, the fiber diameter of the nonwoven fabric after fiber opening is 2µm;

[0145] (6) The sea island fiber spunlace nonwoven fabric after fiber opening treatment was subjected to hot air drying under the following drying conditions: temperature 130°C, time 60 seconds, and speed 50 m / min;

[0146] (7) The dried sea island fiber spunlace nonwoven fabric is passed through a normal temperature roller with the process conditions of pressure of 28 MPa and rotation speed of 10 rpm to obtain a light, high-strength, porous ultrafine fiber nonwoven fabric that can be used as a solid electrolyte support layer.

[0147] Comparative Example 1

[0148] The nonwoven fabric was prepared by the same method as in Example 5, except that: in this comparative example 1, no sea-island fiber was used, and PET fiber was used directly. The specific preparation process is as follows:

[0149] (1) The PET fibers were chopped to prepare PET fibers with a length of 5 mm (fiber diameter of 15 μm);

[0150] (2) The pretreated PET fibers were stirred with water (PET fiber mass content 0.05 wt%), 0.01% carboxymethyl cellulose dispersant and 0.01% polyether defoamer were added, and then pumped into a deflaking machine for deflaking. After deflaking, the slurry was prepared according to the demand;

[0151] (3) wet-making the mixed slurry by downstream printing to form a PET fiber web;

[0152] (4) The formed fiber web is transported to the hydroentanglement unit for hydroentanglement, wherein the high-pressure water needle punctures the fiber web so that the fibers therein are entangled and reinforced with each other. The process conditions are: hydroentanglement pressure of 35 MPa, hydroentanglement curtain running speed of 75 m / min, and the weight is 16 g / m 2 PET fiber spunlace nonwoven fabric;

[0153] (5) The PET fiber spunlace nonwoven fabric was hot-air dried under the following conditions: temperature of 130°C, time of 60 seconds, and speed of 50 m / min;

[0154] (6) The dried PET fiber spunlace nonwoven fabric is passed through a normal temperature roller with the following process conditions: pressure of 20 MPa and speed of 10 rpm.

[0155] Comparative Example 2

[0156] The nonwoven fabric was prepared by the same method as in Example 5, except that: in this comparative example 2, no island fiber was used, and PP fiber was used directly. The specific preparation process is as follows:

[0157] (1) The PP fibers were chopped to prepare PP fibers with a length of 5 mm (fiber diameter of 15 μm);

[0158] (2) The pretreated PP fibers were stirred with water (PP fiber mass content 0.05 wt%), 0.01% carboxymethyl cellulose dispersant and 0.01% polyether defoamer were added, and then pumped into a deflaking machine for deflaking. After deflaking, the slurry was prepared according to the demand;

[0159] (3) The mixed slurry is wet-laid by a downstream method to form a PP fiber web;

[0160] (4) The formed fiber web is transported to the spunlace unit for spunlace, wherein the high-pressure water needle punctures the fiber web so that the fibers therein are entangled and reinforced with each other. The process conditions are: the spunlace pressure is 35 MPa, the spunlace curtain running speed is 75 m / min, and the gram weight is 16 g / m 2 PP fiber spunlace nonwoven fabric;

[0161] (5) The PP fiber spunlace nonwoven fabric was hot-air dried under the following conditions: temperature of 130°C, time of 60 seconds, and speed of 50 m / min;

[0162] (6) The dried PP fiber spunlace nonwoven fabric is passed through a normal temperature roller with the following process conditions: pressure of 20 MPa and speed of 10 rpm.

[0163] Comparative Example 3

[0164] The nonwoven fabric was prepared by the same method as in Example 5, except that the nonwoven fabric was prepared directly by hydroentanglement without wet papermaking in Comparative Example 2. The specific preparation process is as follows:

[0165] (1) The PET / COPET island fibers were opened and carded into a web (fiber length 38 mm, diameter 15 μm);

[0166] (2) The formed fiber web is transported to the spunlace unit for spunlace, wherein the high-pressure water needle punctures the fiber web so that the fibers therein are entangled and reinforced with each other. The process conditions are: the spunlace pressure is 35MPa, the spunlace curtain running speed is 75m / min, and the gram weight is 32g / m 2 Sea-island fiber spunlace nonwoven fabric;

[0167] (3) The sea island fiber spunlace nonwoven fabric was subjected to alkali reduction and fiber opening. The process conditions were: NaOH solution concentration of 10 g / L, temperature of 100 °C, time of 75 minutes, and the weight of the microfiber nonwoven fabric after fiber opening was 16 g / m 2 ;

[0168] (4) The microfiber spunlace nonwoven fabric after fiber opening treatment is subjected to hot air drying. The drying conditions are: temperature 130°C, time 60 seconds, and speed 50 m / min;

[0169] (5) The dried microfiber spunlace nonwoven fabric is passed through a normal temperature roller with the following process conditions: pressure of 20 MPa and speed of 10 rpm.

[0170] Comparative Example 4

[0171] The nonwoven fabric was prepared by the same method as in Example 5, except that the concentration of the sodium hydroxide solution in step (5) was increased in this comparative example 4. The specific preparation process is as follows:

[0172] (1) PET / COPET island fibers (mass ratio of PET to COPET is 5:5) are chopped to obtain pretreated island fibers; the length of the chopped island fibers is 5 mm and the diameter of the island fibers is 15 μm;

[0173] (2) The pretreated sea island fiber is stirred with water (the mass content of the sea island fiber is 0.05 wt%), 0.01% of carboxymethyl cellulose dispersant and 0.01% of polyether defoamer are added, and then pumped into a deflaking machine for deflaking. After deflaking, the slurry is prepared according to the demand;

[0174] (3) The mixed slurry is wet-laid by a downstream method to form a sea-island fiber web;

[0175] (4) The formed fiber web is transported to the hydroentanglement unit for hydroentanglement, wherein the high-pressure water needle punctures the fiber web so that the fibers therein are entangled and reinforced with each other. The process conditions are: hydroentanglement pressure of 35 MPa, hydroentanglement curtain running speed of 75 m / min, and the weight is 16 g / m 2 Sea-island fiber spunlace nonwoven fabric;

[0176] (5) The sea island fiber spunlace nonwoven fabric was subjected to alkali reduction and fiber opening. The process conditions were: NaOH solution concentration of 15 g / L, temperature of 100 °C, and time of 90 minutes. The weight of the sea island fiber spunlace nonwoven fabric after fiber opening was 7 g / m 2 ;

[0177] (6) The sea island fiber spunlace nonwoven fabric after fiber opening treatment was subjected to hot air drying under the following drying conditions: temperature 130°C, time 60 seconds, and speed 50 m / min;

[0178] (7) The dried sea island fiber spunlace nonwoven fabric is passed through a normal temperature roller with the process conditions of pressure of 20 MPa and rotation speed of 10 rpm to obtain a nonwoven fabric.

[0179] Comparative Example 5

[0180] The nonwoven fabric was prepared by the same method as in Example 5, except that the concentration of the sodium hydroxide solution in step (5) was reduced in this comparative example 5. The specific preparation process is as follows:

[0181] (1) PET / COPET island fibers (mass ratio of PET to COPET is 5:5) are chopped to obtain pretreated island fibers; the length of the chopped island fibers is 5 mm and the diameter of the island fibers is 15 μm;

[0182] (2) The pretreated sea island fiber is stirred with water (the mass content of the sea island fiber is 0.05 wt%), 0.01% of carboxymethyl cellulose dispersant and 0.01% of polyether defoamer are added, and then pumped into a deflaking machine for deflaking. After deflaking, the slurry is prepared according to the demand;

[0183] (3) The mixed slurry is wet-laid by a downstream method to form a sea-island fiber web;

[0184] (4) The formed fiber web is transported to the hydroentanglement unit for hydroentanglement, wherein the high-pressure water needle punctures the fiber web so that the fibers therein are entangled and reinforced with each other. The process conditions are: hydroentanglement pressure of 35 MPa, hydroentanglement curtain running speed of 75 m / min, and the weight is 16 g / m 2 Sea-island fiber spunlace nonwoven fabric;

[0185] (5) The sea island fiber spunlace nonwoven fabric was subjected to alkali reduction and fiber opening. The process conditions were: NaOH solution concentration of 1 g / L, temperature of 100 °C, time of 90 minutes, and the weight of the sea island fiber spunlace nonwoven fabric after fiber opening was 18 g / m 2 ;

[0186] (6) The sea island fiber spunlace nonwoven fabric after fiber opening treatment was subjected to hot air drying under the following drying conditions: temperature 130°C, time 60 seconds, and speed 50 m / min;

[0187] (7) The dried sea island fiber spunlace nonwoven fabric is passed through a normal temperature roller with the process conditions of pressure of 20 MPa and rotation speed of 10 rpm to obtain a nonwoven fabric.

[0188] Comparative Example 6

[0189] The nonwoven fabric was prepared by the same method as in Example 5, except that no normal temperature rolling operation was performed in this comparative example 6. The specific preparation process is as follows:

[0190] (1) PET / COPET island fibers (mass ratio of PET to COPET is 5:5) are chopped to obtain pretreated island fibers; the length of the chopped island fibers is 5 mm and the diameter of the island fibers is 15 μm;

[0191] (2) The pretreated sea island fiber is stirred with water (the mass content of the sea island fiber is 0.05 wt%), 0.01% of carboxymethyl cellulose dispersant and 0.01% of polyether defoamer are added, and then pumped into a deflaking machine for deflaking. After deflaking, the slurry is prepared according to the demand;

[0192] (3) The mixed slurry is wet-laid by a downstream method to form a sea-island fiber web;

[0193] (4) The formed fiber web is transported to the hydroentanglement unit for hydroentanglement, wherein the high-pressure water needle punctures the fiber web so that the fibers therein are entangled and reinforced with each other. The process conditions are: hydroentanglement pressure of 35 MPa, hydroentanglement curtain running speed of 75 m / min, and the weight is 16 g / m 2 Sea-island fiber spunlace nonwoven fabric;

[0194] (5) The sea island fiber spunlace nonwoven fabric was subjected to alkali reduction and fiber opening. The process conditions were: NaOH solution concentration of 10 g / L, temperature of 100 °C, and time of 90 minutes. The weight of the sea island fiber spunlace nonwoven fabric after fiber opening was 8 g / m 2 , the fiber diameter of the nonwoven fabric after fiber opening is 0.8µm;

[0195] (6) The sea island fiber spunlace nonwoven fabric after fiber opening treatment was subjected to hot air drying under the following drying conditions: temperature of 130°C, time of 60 seconds, and speed of 50 m / min; and a nonwoven fabric was obtained.

[0196] The nonwoven fabrics prepared in the above examples and comparative examples were subjected to performance tests. The specific test results are shown in Table 1 below. The test methods involved are as follows:

[0197] (1) Weight:

[0198] The experiment was conducted according to the national standard GB / T451.2-1989. Samples with an area of ​​100 square centimeters were uniformly cut from paper or cardboard. Each sample was weighed using a balance with an accuracy of 0.001g and the weight of each sample was recorded. The determination formula is as follows:

[0199] ;

[0200] Where:

[0201] G —Weight, g / m 2 ;

[0202] M —Sample mass, g;

[0203] A —Sample area, m 2 .

[0204] (2) Thickness:

[0205] The experiment is conducted according to the national standard GB / T 24218.2-2009. A static load is applied to a single-layer specimen, and the distance between the two surfaces of the specimen is measured. The result is expressed in millimeters or microns.

[0206] (3) Porosity

[0207] The porosity is determined by the method of absorbing n-butanol by the sample. That is, a 30mm×30mm sample is cut, dried at (105±1)℃ for 4 hours, weighed, and completely immersed in n-butanol solution. After 2 hours, it is taken out and the residual liquid on the surface is wiped off with filter paper. The sample is weighed and the volume of the nonwoven fabric is calculated. V , the determination formula is as follows:

[0208] ;

[0209] Where:

[0210] P —porosity, %;

[0211] W 1 —absolute dry mass of the sample, g;

[0212] W 2 —Mass of the sample after immersion in n-butanol, g;

[0213] 𝛒 b —density of n-butanol, g / cm 3 .

[0214] (4) Tensile breaking strength:

[0215] The experiment was conducted in accordance with the national standard GB / T_12914-2018. A sample with a width of 15 mm and a length of 250 mm was cut from the paper in both the longitudinal and transverse directions using a cutting knife. The chuck position of the testing machine was adjusted to 180 mm ± 1 mm for the test length (average distance between the clip lines) and the stretching rate was adjusted to 20 mm / min ± 5 mm / min. The sample was placed on the test chuck and the tensile strength tester was started to stretch the sample at a rate of 20 mm / min ± 5 mm / min until the sample broke. The specific calculation formula is as follows:

[0216] ;

[0217] Where:

[0218] S —Tensile breaking strength, N / 15mm;

[0219] F—Tensile breaking strength of the specimen, N;

[0220] B —Specimen width, mm.

[0221] Table 1 Test data of nonwoven fabrics

[0222]

[0223] The nonwoven fabrics prepared in the above examples and comparative examples were used as solid electrolyte support layers to test battery performance, wherein the battery assembly method was as follows:

[0224] Polyethylene oxide (PEO, M W =600000 g / mol, Aladdin) and lithium trifluoromethanesulfonyl imide (LiTFSI, 99.99%, Aladdin) were dissolved in anhydrous acetonitrile (CH3CN) solution to obtain a mixed solution, which was then scraped onto a solid electrolyte support layer to allow PEO to bond to the solid electrolyte support layer, and then dried to obtain a solid electrolyte.

[0225] The battery was assembled by lamination in a glove box (O2 < 0.1 ppm, H2O < 0.1 ppm) with a lithium metal electrode (purchased from Lizhiyuan Battery Sales Department, Yingze District, Taiyuan City), the solid electrolyte prepared above, and a LiFePO4 positive electrode (purchased from Lizhiyuan Battery Sales Department, Yingze District, Taiyuan City).

[0226] The test results of solid electrolyte and battery performance are shown in Table 2 below. The test methods involved are:

[0227] (1) Solid electrolyte mechanical properties test:

[0228] The strength of the prepared solid electrolyte was tested using a YG005 single fiber strength tester. The sample size was 5 mm × 30 mm, and the tensile rate was 10 mm / min. The fracture strength of the electrolyte was calculated using the formula:

[0229] ;

[0230] Where: σ is the fracture strength of the solid electrolyte (MPa), P is the strength of the solid electrolyte (cN), b is the width of the solid electrolyte (cm), d is the thickness of the solid electrolyte (μm).

[0231] (2) Ionic conductivity test:

[0232] Impedance was measured using a CHI 660D electrochemical workstation. The battery structure consisted of a positive electrode shell-steel sheet-all-solid-state composite electrolyte-steel sheet-shrapnel-negative electrode shell. Parameters were set as open circuit voltage, high frequency of 106 Hz, low frequency of 0.01 Hz, and amplitude of 0.005 A. Ionic conductivity was calculated using the following formula:

[0233] ;

[0234] in σ is the ionic conductivity, d represents the thickness of the electrolyte (μm), Rt is the resistance of the electrolyte (Ω), S is the effective contact area between the electrolyte and the steel sheet (cm 2 ).

[0235] (3) Ion migration number test:

[0236] A CHI 660D electrochemical workstation was used. The battery structure was positive electrode shell-lithium sheet-all-solid composite electrolyte-lithium sheet-steel sheet-shrapnel-negative electrode shell. The initial potential was 0.0098 V, the sampling interval was 1 s, the experimental time was 6000 s, and the sensitivity was e -0.03 In this experiment, the lithium ion transference number (t Li + ).

[0237] (4) Capacity retention test:

[0238] The LAND-BT2013C battery test system was used to perform charge and discharge cycle tests at room temperature. The capacity retention rate after 100 cycles at 0.1C was calculated using the following formula:

[0239] ;

[0240] Where: C is the capacity retention rate after 100 cycles at 0.1C (%), C 100 is the discharge capacity at the 100th cycle (mAh), C 0 is the discharge capacity of the first cycle (mAh).

[0241] Table 2 Battery performance test results

[0242]

[0243] The data in Tables 1 and 2 above demonstrate that the nonwoven fabrics produced using the methods described herein in Examples 1-9 exhibit lightweight, high-strength, and porous properties. The nonwoven fabrics also exhibit more uniform mechanical strength in both the longitudinal and transverse directions, and possess higher puncture and tear resistance. Their use as a solid electrolyte support layer effectively increases battery energy density and reduces ionic conductivity requirements, facilitating the high energy density, safety, and large-scale industrial production of solid-state batteries. Figure 1 This is an SEM image of the nonwoven fabric before alkali weight reduction and fiber opening in Example 1; Figure 2 The SEM image of the nonwoven fabric after alkali weight reduction and fiber opening in Example 1 is shown in FIG. Figure 1 and Figure 2 It can be seen that: Figure 1 (Before alkali reduction and fiber opening) shows that the nonwoven fabric is composed of 15-25μm sea-island fibers, with loose fiber entanglements and large and unevenly distributed pores; Figure 2 (After fiber opening), the fibers are separated into ultrafine fibers of 0.8-4μm after NaOH treatment, with increased entanglement density, forming a fine and uniform three-dimensional network with small and regular pores and significantly improved porosity, meeting the requirements of the solid electrolyte support layer for being "light, strong, and porous".

[0244] From the comparison of the experimental results of Comparative Example 1, Comparative Example 2, Comparative Example 3 and Example 5, it can be seen that the non-woven fabric made of sea-island fibers in the present invention has a thinner thickness and better porosity than conventional PET fibers, PP fibers and sea-island fiber non-woven fabrics after fiber opening. When applied to solid-state electrolyte batteries, it is more conducive to improving the battery energy density and reducing the ion conductivity requirements. Moreover, its strength performance can also meet the requirements of the roll-to-roll production process.

[0245] Comparing the experimental results of Comparative Example 4 and Example 5 shows that if the sodium hydroxide concentration is too high (15g / L), the nonwoven fabric's grammage is too low (5.7g / m²), the fiber structure is excessively corroded, and some fibers break. Although the porosity is high (79.3%), the mechanical properties are degraded (the longitudinal tensile strength is 4.72N / 15mm, and the transverse tensile strength is 4.66N / 15mm, lower than the 5.51N / 15mm and 6.06N / 15mm in Example 5). This is because excessively high alkali concentrations disrupt the interfacial bonding between the PET and COPET layers in the island-in-the-sea fibers, compromising fiber integrity and reducing the structural stability of the support layer. This makes it difficult for the electrolyte support layer to withstand the mechanical stresses of roll-to-roll production. Furthermore, fiber breakage can lead to uneven pore distribution, affecting uniform electrolyte filling.

[0246] Comparison of the experimental results of Comparative Example 5 and Example 5 shows that if the concentration of sodium hydroxide is too low (1g / L), the fiber opening will be insufficient, the "island phase" (PET) in the sea-island fiber will not be completely separated, the fiber diameter will be larger, the porosity will be reduced (64.3%, lower than 76.6% in Example 5), and the gram weight will be high (11.3g / m²). Because the low concentration of alkali solution cannot effectively dissolve the "sea phase" (COPET), the fiber cannot be refined, resulting in an underdeveloped pore structure of the support layer, making it difficult for the electrolyte to fully penetrate, reducing the ion transmission path and decreasing the ionic conductivity (0.9×10⁻ 4 S・cm⁻¹, lower than 1.9×10⁻ in Example 5 4 S・cm⁻¹), while thicker fiber structures increase the overall thickness of the battery, which is not conducive to improving energy density. Therefore, the nonwoven fabric obtained by using the sodium hydroxide concentration (5-12g / L) described in the present invention is more suitable for use as a solid electrolyte support layer.

[0247] Comparing the experimental results of Comparative Example 6 and Example 5 shows that without the room-temperature rolling operation, the nonwoven fabric's thickness increases (13.6 μm, higher than the 10.6 μm in Example 5), the pore structure becomes less compact, and the longitudinal and transverse tensile strengths are slightly lower (5.03 N / 15 mm and 4.82 N / 15 mm, lower than the 5.51 N / 15 mm and 6.06 N / 15 mm in Example 5). This is because the rolling operation tightly entangles the fibers through mechanical pressure, reducing thickness while increasing interfiber cohesion and enhancing mechanical properties. The unrolled support layer is thicker, increasing the battery's "dead volume" and reducing energy density. Furthermore, the loose structure may lead to localized voids after electrolyte filling, increasing interfacial impedance.

[0248] The technical features of the above-described embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are exhaustively listed. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0249] For those skilled in the art, several variations and improvements may be made without departing from the scope of the present invention, which all fall within the scope of protection of the present invention. The scope of protection of the present invention shall be based on the appended claims.

Claims

1. A method for preparing a nonwoven fabric for a solid electrolyte support layer, characterized in that: The preparation method is: S1, chopping the island-in-the-sea fibers to obtain pretreated island-in-the-sea fibers; S2: disintegrating the pretreated island fiber in water to obtain a slurry; S3: wet-papering the slurry to form a fiber web; S4: hydroentangle the fiber web to obtain a formed sea-island fiber hydroentangled nonwoven fabric; S5: alkali reduction and fiber opening of sea-island fiber spunlace nonwoven fabric; S6: drying the sea-island fiber spunlace nonwoven fabric after the fiber opening treatment; S7: passing the dried sea-island fiber spunlace nonwoven fabric through a roller, winding it up and slitting it to obtain a nonwoven fabric for a solid electrolyte support layer; In step S1, the components of the sea-island fiber are PET and COPET; In step S4, the spunlace pressure is 30-40 bar, the spunlace curtain running speed is 70-80 m / min, and the weight of the sea-island fiber spunlace nonwoven fabric is 16-32 g / m 2 In step S5, during the alkali weight reduction and fiber opening treatment, the weight reduction solution used is a NaOH solution with a concentration of 5-12 g / L; the temperature during the alkali weight reduction and fiber opening treatment is 90-100° C. and the time is 30-90 min; the fiber diameter of the sea-island fiber spunlace nonwoven fabric after the alkali weight reduction and fiber opening treatment is 0.8-4 μm; In step S7, the roller pressure is 10-30 MPa, the speed is 8-12 rpm, and the temperature is room temperature; In step S6, after drying, the weight of the sea island fiber spunlace nonwoven fabric after fiber opening treatment is 8-20 g / m 2 .

2. The method for preparing a nonwoven fabric for a solid electrolyte support layer according to claim 1, characterized in that: The mass ratio of PET and COPET is (3:7)-(7:3).

3. The method for preparing a nonwoven fabric for a solid electrolyte supporting layer according to claim 1, characterized in that: In step S1, the diameter of the island-in-the-sea fibers is 15-25 μm, and the length of the chopped island-in-the-sea fibers is 4-6 mm.

4. The method for preparing a nonwoven fabric for a solid electrolyte supporting layer according to claim 1, characterized in that: In step S2, a dispersant and a defoaming agent are added during the decomposition operation; The dispersant is at least one of carboxymethyl cellulose, polyethylene oxide, and sodium lauryl sulfate; The defoaming agent is at least one of a polyether defoaming agent and a silicone defoaming agent.

5. The method for preparing a nonwoven fabric for a solid electrolyte supporting layer according to claim 4, characterized in that: In the slurry, the mass content of the pretreated sea-island fiber is 0.05-0.10%; the mass content of the dispersant is 0.01-0.1%; and the mass content of the defoaming agent is 0.01-0.1%.

6. A nonwoven fabric for a solid electrolyte support layer, characterized in that: The nonwoven fabric for the solid electrolyte supporting layer is prepared according to the preparation method according to any one of claims 1 to 5; The nonwoven fabric used for the solid electrolyte support layer has a gram weight of 8-16 g / m 2 , thickness does not exceed 30µm, porosity is 40%-80%; longitudinal and transverse tensile strength is above 3N / 15mm.

7. An application of a nonwoven fabric for a solid electrolyte supporting layer according to claim 6, characterized in that: The nonwoven fabric for a solid electrolyte supporting layer is used as a solid electrolyte supporting layer in a battery.

Images