Non-woven fabric, diaphragm and battery

Abstract

The invention provides a non-woven fabric, a diaphragm and a battery, the non-woven fabric comprises at least one fine fiber layer and at least one crude fiber layer which are laminated, the fine fiber layer and the crude fiber layer respectively comprise main fibers, the main fibers comprise circular cross-section fibers and special-shaped cross-section fibers, and the cross-section fibers comprise circular cross-section fibers and special-shaped cross-section fibers. The perimeter coefficient of the cross section of at least part of the special-shaped cross section fibers is XL, and XL is larger than 1 and smaller than or equal to 5; the linear density of the main fibers of the fine fiber layer is smaller than that of the main fibers of the crude fiber layer. The strength of the non-woven fabric and the wettability of the non-woven fabric to electrolyte can be improved.

Description

Non-woven fabric, diaphragm and battery Technical Field

[0001] The present invention relates to the technical field of non-woven fabric materials, and in particular to a non-woven fabric, a diaphragm and a battery. Background Art

[0002] Non-woven fabrics have naturally large pores, high porosity, and high-temperature resistance, offering promising applications in energy storage devices like batteries. For example, they can be used as non-woven separators in batteries. However, improvements in related technologies, such as non-woven fabric strength and electrolyte wettability, are urgently needed.

[0003] Summary of the Invention

[0004] The present invention provides a non-woven fabric, a separator and a battery, which can improve the strength of the non-woven fabric and its wettability to electrolyte and other properties.

[0005] In one aspect of the present invention, a nonwoven fabric is provided, comprising at least one fine fiber layer and at least one coarse fiber layer stacked together, wherein the fine fiber layer and the coarse fiber layer each comprise a main fiber, wherein the main fiber comprises a circular cross-section fiber and a shaped cross-section fiber, and the perimeter coefficient of the cross section of at least part of the shaped cross-section fiber is X L , 1<X L ≤5; the linear density of the trunk fibers of the fine fiber layer is less than the linear density of the trunk fibers of the coarse fiber layer.

[0006] Another aspect of the present invention provides a separator comprising the aforementioned non-woven fabric.

[0007] According to another aspect of the present invention, a battery is provided, comprising the aforementioned separator.

[0008] In the present invention, the nonwoven fabric adopts a composite structure of two or more fiber layers, including at least one fine fiber layer and at least one coarse fiber layer, and the main fibers in the fine fiber layer and the coarse fiber layer respectively include circular cross-section fibers and special-shaped cross-section fibers, and the perimeter coefficient X of the cross section of at least part of the special-shaped cross-section fibers is controlled. L Satisfy 1<X L≤5, thereby introducing these specific forms of fibers into the non-woven fabric and forming a specific fiber arrangement structure, which is conducive to full bonding between the fibers, forming a strong network structure and a suitable pore structure and other characteristics, thereby improving the strength of the non-woven fabric and maintaining a relatively thin thickness of the non-woven fabric. At the same time, the wettability of the non-woven fabric to the electrolyte can be improved, so that the non-woven fabric separator formed by the non-woven fabric has high liquid absorption and liquid retention rates in non-all-solid-state batteries, which is conducive to the uniform distribution of the electrolyte in non-all-solid-state batteries; in addition, the non-woven fabric can also have good filling properties. For example, in a solid electrolyte membrane with the non-woven fabric as the base material, the filling density and loading amount of the solid electrolyte in the non-woven fabric can be improved, so that the solid electrolyte can be fully and effectively filled, thereby improving the interface contact and other properties of the solid electrolyte. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG1 is a schematic diagram of the cross-sectional shape (quadrangular star) of a special-shaped cross-section fiber according to an embodiment of the present invention;

[0010] FIG2 is a schematic diagram of a cross-sectional shape (T-shaped) of a special-shaped cross-section fiber according to another embodiment of the present invention;

[0011] FIG3 is a schematic diagram of the cross-sectional shape (rectangle with missing corners) of a special-shaped cross-section fiber according to another embodiment of the present invention;

[0012] FIG4 is a schematic diagram of the cross-sectional shape (heart-shaped) of a special-shaped cross-sectional fiber according to another embodiment of the present invention;

[0013] FIG5 is a schematic diagram of the cross-sectional shape (W-shaped) of a special-shaped cross-sectional fiber according to another embodiment of the present invention;

[0014] FIG6 is a schematic diagram of the cross-sectional shape (meniscus shape) of a special-shaped cross-section fiber according to another embodiment of the present invention;

[0015] FIG7 is a schematic diagram of the cross-sectional shape (cross shape) of a special-shaped cross-sectional fiber according to another embodiment of the present invention;

[0016] FIG8 is a schematic diagram of the cross-sectional shape (hexagonal) of a special-shaped cross-sectional fiber according to another embodiment of the present invention;

[0017] FIG9 is a schematic diagram of the cross-sectional shape (quadrilateral) of a special-shaped cross-section fiber according to another embodiment of the present invention;

[0018] FIG10 is a schematic diagram of the cross-sectional shape (hexagram) of a special-shaped cross-section fiber according to another embodiment of the present invention;

[0019] FIG11 is a schematic diagram of the cross-sectional shape (open circular shape) of a special-shaped cross-section fiber according to another embodiment of the present invention;

[0020] FIG12 is a schematic diagram of the cross-sectional shape (hexagonal star) of a special-shaped cross-section fiber according to another embodiment of the present invention;

[0021] FIG13 is a schematic diagram of the cross-sectional shape (crescent shape) of a special-shaped cross-section fiber according to another embodiment of the present invention;

[0022] FIG14 is a schematic diagram of the cross-sectional shape (U-shaped) of a special-shaped cross-sectional fiber according to another embodiment of the present invention;

[0023] FIG15 is a schematic diagram of the cross-sectional shape (non-complete circular shape) of a fiber with a special cross-section in another embodiment of the present invention;

[0024] FIG16 is a differential scanning calorimetry curve of the fiber.

[0025] Explanation of reference numerals: 1: cross section of a fiber with a special cross section; 10: groove; 100: circumscribed circle; w: width of the groove at its widest point; h: depth of the groove at its deepest point. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below. The specific embodiments listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts are within the scope of protection of the present invention.

[0027] Non-woven fabrics have naturally large pores and high porosity, and have good application prospects in the field of energy storage devices such as batteries. For example, they can be used for non-woven fabric membranes. Non-woven fabric membranes can be widely used in lead-acid batteries, alkaline batteries, nickel-hydrogen batteries and supercapacitors. They have the advantages of high temperature resistance and high porosity, especially the safety advantages compared with traditional polyolefin membranes, which makes them have good application prospects in large batteries, especially suitable for large-scale energy storage and power batteries with long cycle life requirements. Therefore, they are increasingly attracting attention from the lithium battery industry.

[0028] However, in related technologies, the strength of non-woven fabrics and their wettability with electrolytes need to be further improved. For example, it is often difficult to strike a balance between the strength and thickness of non-woven fabrics. Reducing the thickness of the non-woven fabric will weaken its strength, which is detrimental to battery safety and cycle life. However, increasing the thickness of the non-woven fabric will affect battery performance such as energy density.

[0029] For example, an electrolyte is an ionic conductor that conducts ions between the positive and negative electrodes of a battery, transporting ions back and forth between them during the battery's charge and discharge processes. Ideally, there should be sufficient electrolyte between the positive and negative electrodes to ensure sufficient ion transfer rates during the charge and discharge process. However, during the actual charge and discharge process, both the positive and negative electrodes undergo a certain volume change, causing the battery cell to also experience a certain degree of volume expansion and contraction. This results in an uneven distribution of the electrolyte solution (electrolyte) within the battery cell in non-solid-state batteries (which typically contain electrolytes). In particular, during the battery's charging process, as the electrodes expand, some "dry areas" (i.e., areas with very little or no electrolyte) are formed within the battery cell. The presence of these "dry areas" reduces the amount of active material that can participate in the charge and discharge reactions, causing uneven local state of charge (SOC) within the battery, limiting the diffusion rate of lithium ions, causing the lithium ion concentration to fluctuate with the charge and discharge process, and accelerating local aging within the battery.

[0030] The distribution of electrolyte in fresh batteries is also significantly uneven, with significantly more electrolyte outside the cell than inside. When electrolyte penetration is poor, the ion transmission path becomes longer, hindering the movement of lithium ions between the positive and negative electrodes. Electrodes not exposed to the electrolyte cannot participate in the battery's electrochemical reactions, and the battery's interfacial resistance increases, affecting the battery's rate performance, discharge capacity, and service life. Therefore, ensuring that the electrolyte fully and evenly penetrates the cell to maintain the battery's electrochemical performance and cycle life has long been a technical challenge that needs to be addressed in this field.

[0031] In addition, compared with liquid batteries that use electrolytes, solid-state batteries that use solid electrolytes instead of electrolytes have more advantages in terms of safety and energy density (for example, the combination of solid electrolytes and metal lithium negative electrodes in solid-state batteries is expected to achieve higher energy density). However, due to the lack of fluidity of solid electrolytes, the solid electrolyte membranes used generally have problems such as small solid-solid contact area and increased impedance. These problems have restricted the development of solid-state batteries.

[0032] In view of this, an embodiment of the present invention provides a non-woven fabric, comprising at least one layer of fine fiber layer and at least one layer of coarse fiber layer stacked, wherein the fine fiber layer and the coarse fiber layer respectively include trunk fibers, the trunk fibers include circular cross-section fibers (circular cross-section trunk fibers) and special-shaped cross-section fibers (special-shaped cross-section trunk fibers), and the perimeter coefficient of the cross section 1 of at least part (i.e., part or all) of the special-shaped cross-section fibers is X L , 1<X L ≤5; the linear density of the main fibers of the fine fiber layer is less than the linear density of the main fibers of the coarse fiber layer.

[0033] Therefore, the non-woven fabric provided by the embodiment of the present invention has an overall structure composed of at least two fiber layers (at least one fine fiber layer and at least one coarse fiber layer). Through the specific fiber combination and specific fiber arrangement, the fibers are fully bonded to each other, forming a strong network structure and a suitable pore structure. The non-woven fabric of the embodiment of the present invention can have the following properties:

[0034] (1) Improve the strength of non-woven fabrics and keep the thickness of non-woven fabrics thin. For example, the thickness of non-woven fabrics can be no more than 30 μm, further no more than 25 μm, or even as low as 9 μm or less. At this time, its longitudinal tensile strength can be as high as 500 kgf / cm 2 As described above, the non-woven fabric of the embodiment of the present invention is a thin and high-strength non-woven fabric;

[0035] (2) Improving the wettability of the non-woven fabric to the electrolyte, so that the non-woven fabric diaphragm formed by the non-woven fabric has a high liquid absorption and liquid retention rate in the non-solid-state battery (the electrolyte absorption rate can be as high as more than 255% or even more than 290%), which is beneficial to the full infiltration and uniform distribution of the electrolyte in the non-solid-state battery in the battery cell, reducing the interface resistance, thereby improving the rate performance, discharge capacity and service life of the battery (such as lithium battery).

[0036] (3) The non-woven fabric can also have good filling properties. For example, in a solid electrolyte membrane with the non-woven fabric as the base material, the filling density and loading amount of the solid electrolyte in the non-woven fabric can be improved, so that the solid electrolyte can be fully and effectively filled, thereby improving the interface contact and other properties of the solid electrolyte.

[0037] In addition, according to the inventor's research, if the perimeter coefficient X of the above-mentioned special-shaped cross-section fiber L When the fiber surface area is greater than 5, although the fiber specific surface area increases, the excessive grooves and protrusions on the fiber surface can easily cause entanglement between fibers with irregular cross-sections, making it easy for the main fibers in the fiber layer to clump together, making it difficult to fully disperse evenly, which is not conducive to obtaining a non-woven fabric with high performance uniformity.

[0038] Specifically, the non-woven fabric may be a double-layer structure, that is, it has two stacked fiber layers, one of which is a fine fiber layer and the other is a coarse fiber layer, that is, the non-woven fabric is composed of a stacked fine fiber layer and a coarse fiber layer.

[0039] Alternatively, the above-mentioned non-woven fabric may also be a structure of at least three layers, that is, it includes at least three fiber layers. For example, a fine fiber layer or a coarse fiber layer may be provided on the side of the fine fiber layer of the above-mentioned double-layer non-woven fabric facing away from the coarse fiber layer, or a fine fiber layer or a coarse fiber layer may be provided on the side of the coarse fiber layer of the above-mentioned double-layer non-woven fabric facing away from the fine fiber layer to form a three-layer non-woven fabric.

[0040] Generally, in the above-mentioned non-woven fabric, the fine fiber layer and the coarse fiber layer are staggered, that is, when the above-mentioned at least two fiber layers include at least two fine fiber layers (that is, the non-woven fabric includes at least two fine fiber layers), there is a coarse fiber layer between each two adjacent fine fiber layers, so that the two adjacent fine fiber layers are separated by a coarse fiber layer; when the above-mentioned at least two fiber layers include at least two coarse fiber layers (that is, the non-woven fabric includes at least two coarse fiber layers), there is a fine fiber layer between each two adjacent coarse fiber layers, so that the two adjacent coarse fiber layers are separated by a fine fiber layer.

[0041] Illustratively, the nonwoven fabric includes a coarse fiber layer and fine fiber layers located on opposite sides of the coarse fiber layer; or, the nonwoven fabric includes a fine fiber layer and coarse fiber layers located on opposite sides of the fine fiber layer.

[0042] Specifically, the above-mentioned at least one fine fiber layer and at least one coarse fiber layer are composited to form the overall structure of the non-woven fabric. The strength performance of the coarse fiber layer is generally higher than that of the fine fiber layer. Therefore, the coarse fiber layer (coarse fiber reinforced layer) mainly serves as a structural reinforcement layer to provide support strength for the non-woven fabric. At the same time, it is combined with the fine fiber layer (fine fiber pore layer) to form a composite structure of fine fiber pore layer-coarse fiber reinforced layer, which enhances the overall strength of the non-woven fabric and optimizes the wettability and filling properties of the non-woven fabric, which is beneficial for its use as a battery separator.

[0043] In some embodiments, the mass ratio of the fine fiber layer to the non-woven fabric can be 10% to 30% (i.e., the fiber content of the fine fiber layer relative to the non-woven fabric as a whole is 10% to 30%), for example, 10%, 15%, 20%, 25%, 30%, or a range consisting of any two thereof. When the non-woven fabric includes at least two fine fiber layers, the mass ratio of the fine fiber layer to the non-woven fabric (10% to 30%) refers to the ratio of the sum of the masses of these fine fiber layers to the total mass of the non-woven fabric.

[0044] In addition, the mass ratio of the coarse fiber layer to the non-woven fabric can be 70% to 90% (that is, the mass ratio of the coarse fiber layer to the non-woven fabric can be 70% to 90% relative to the non-woven fabric as a whole), for example, 70%, 75%, 80%, 85%, 90% or a range consisting of any two of them. Among them, when the non-woven fabric includes at least two layers of coarse fiber layers, the mass ratio of the coarse fiber layer to the non-woven fabric (70% to 90%) refers to the ratio of the sum of the masses of these coarse fiber layers to the mass of the non-woven fabric.

[0045] Specifically, in the above-mentioned non-woven fabric, each fiber layer includes trunk fibers, and the trunk fibers of each fiber layer include circular cross-section fibers and irregular cross-section fibers, that is, the trunk fibers of each fine fiber layer include circular cross-section fibers and irregular cross-section fibers, and the trunk fibers of each coarse fiber layer include circular cross-section fibers and irregular cross-section fibers.

[0046] In each fiber layer, the perimeter coefficient X of the cross section 1 of at least part of the special-shaped cross-section fiber is L Satisfy 1<X L ≤5, that is, the perimeter coefficient X of at least some of the special-shaped cross-section fibers in each fiber layer is L Satisfy 1<X L ≤5, that is, the perimeter coefficient X of at least some of the profiled cross-section fibers in each fine fiber layer is L Satisfy 1<X L ≤5, the perimeter coefficient X of at least part of the special-shaped cross-section fibers in each coarse fiber layer L Satisfy 1<X L ≤5.

[0047] Specifically, for each thin fiber layer or each coarse fiber layer, there may be one type of shaped cross-section fiber (i.e., the cross-section 1 of these shaped cross-section fibers has the same shape), or there may be multiple types of shaped cross-section fibers (i.e., the cross-section 1 of at least some of the shaped cross-section fibers has a different shape). When there are multiple types of shaped cross-section fibers, the perimeter coefficient X of the cross-section 1 of at least one type of shaped cross-section fiber is L Satisfy 1<X L ≤5, that is, the perimeter coefficient X of the cross section 1 of a special-shaped cross-section fiber L Satisfy 1<X L ≤5, or the perimeter coefficient X of the cross section 1 of at least two types of special-shaped cross-section fibers L Satisfy 1<X L ≤5.

[0048] For example, the perimeter coefficient X of the cross section 1 of the at least partially shaped cross-section fiber is L For example, the range is 1.5, 2, 3, 4, 5 or any two thereof.

[0049] In the above non-woven fabric, the perimeter coefficient X of the cross section 1 of the special-shaped cross-section fiber in each two fiber layers (such as each two coarse fiber layers, or each two fine fiber layers, or each coarse fiber layer and each fine fiber layer) is L They can be equal or different, for example, the perimeter coefficient X of the cross section 1 of the special-shaped cross-section fiber in the fine fiber layer LIt can be equal to, greater than, or less than the perimeter coefficient X of the cross section 1 of the profiled cross-section fiber in the coarse fiber layer. L , there is no special restriction on this.

[0050] Specifically, the profiled cross-section fiber is a non-circular cross-section fiber, that is, its cross section 1 is non-circular, and the cross section 1 is perpendicular to the axial direction of the profiled cross-section fiber (generally also the length direction of the profiled cross-section fiber). The perimeter coefficient X of the cross section 1 of the profiled cross-section fiber is L = The ratio of the perimeter C0 of the cross section of the profiled cross section fiber to the perimeter C1 of a circle with the same area as the cross section 1 of the profiled cross section fiber (ie X L =C0 / C1), which can be specifically measured by the perimeter coefficient determination method in the textile industry standard FZ / T50002-2013 (test method for chemical fiber profile) of the People's Republic of China.

[0051] Specifically, the cross section of the circular cross-section fiber is substantially circular, and the cross section is perpendicular to the axial direction of the circular cross-section fiber (generally also the length direction of the circular cross-section fiber).

[0052] Generally, non-woven fabrics can also include bonding fibers, that is, each coarse fiber layer and each fine fiber layer respectively include bonding fibers. The softening point of the main fiber is greater than that of the bonding fiber. The bonding fiber is mainly used to bond the main fibers and other components in the non-woven fabric to improve the structural strength of the non-woven fabric.

[0053] Specifically, in the preparation process of non-woven fabrics, randomly dispersed fibers (including trunk fibers and bonding fibers) can usually be shaped through a hot calendering process, wherein the trunk fibers serve as the skeleton of the non-woven fabric structure and basically do not melt, while the bonding fiber surface partially or completely melts, thereby penetrating into the fiber surface, as well as the gaps, voids or concave and convex structures between the fibers. After cooling and solidification, a meshing force is generated in the interface area, so that the fibers in the non-woven fabric are bonded to each other, achieving a firm bond between the fibers and giving the non-woven fabric structural strength.

[0054] In general, under the conditions of the same fiber linear density, the same fiber length, and the same fiber cross-sectional area, the specific surface area of ​​the irregular cross-sectional fiber is significantly higher than that of the circular cross-sectional fiber. By introducing the above cross-sectional perimeter coefficient X into the nonwoven fabric, L Satisfy 1<X L≤5, the high specific surface area of ​​the special-shaped cross-section fibers and the pore structure that can form a capillary effect between the fibers can make the melted part of the bonding fibers more fully and quickly infiltrated, so that the bonding area between the fibers is greatly increased, and the structural strength of the non-woven fabric is significantly improved (the non-woven fabric using only circular cross-section fibers usually forms bonding points mainly at the intersection of the fibers, while the non-woven fabric of the embodiment of the present invention introduces the cross-sectional perimeter coefficient X L Satisfy 1<X L ≤5, the structural strength of the special-shaped cross-section fiber is significantly improved).

[0055] In some embodiments, the surface of the above-mentioned special-shaped cross-section fiber can be provided with grooves 10, so that the anchoring effect of the fiber bonding can be further enhanced. The melted part of the bonding fiber penetrates into the micro-grooves 10 on the surface of the special-shaped cross-section fiber through capillary attraction. After cooling and solidification, the fibers cannot move relative to each other, thereby achieving strong bonding between the fibers and further improving the structural strength of the non-woven fabric.

[0056] Specifically, in the special-shaped cross-section fiber, the groove 10 can extend along the axial direction of the special-shaped cross-section fiber and penetrate the special-shaped cross-section fiber in the axial direction of the special-shaped cross-section fiber, that is, the length of the groove 10 on the special-shaped cross-section fiber is equal to the length of the special-shaped cross-section fiber.

[0057] In addition, the number of the grooves 10 in the fiber with a special cross-section may be one or more. When there are multiple grooves 10, these grooves 10 may be distributed along the circumference of the fiber with a special cross-section.

[0058] Specifically, in the special-shaped cross-section fiber, the number of grooves 10 can be less than or equal to 16, that is, 1 to 16 grooves 10 can be set on a special-shaped cross-section fiber, and the number of grooves 10 is, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16, etc., which is conducive to further improving the structural strength of the non-woven fabric.

[0059] Among them, the number of grooves 10 of special-shaped cross-section fibers in every two fiber layers can be the same or different. For example, the number of grooves 10 of special-shaped cross-section fibers in the fine fiber layer can be the same as or different from the number of grooves 10 of special-shaped cross-section fibers in the coarse fiber layer. The number of grooves 10 of special-shaped cross-section fibers in the fine fiber layer can specifically be greater than, equal to or less than the number of grooves 10 of special-shaped cross-section fibers in the coarse fiber layer.

[0060] Generally, each fine fiber layer or coarse fiber layer contains multiple fibers with different cross-sections, and the number of grooves 10 on these fibers with different cross-sections can be the same or different. As previously mentioned, each fine fiber layer or each coarse fiber layer contains at least one type of fiber with different cross-sections, that is, one type of fiber with different cross-sections or multiple types of fibers with different cross-sections can be present. When multiple types of fibers with different cross-sections are present, the number of grooves 10 on any two types of fibers with different cross-sections can be the same or different.

[0061] After further research, from the perspective of sufficient infiltration, the width w of the widest part of the groove 10 is not less than 15% of the diameter D of the circumscribed circle 100 of the cross-section 1 of the special-section fiber, which is more conducive to removing the air inside the groove 10, so that the fluid can fully infiltrate the inside of the groove 10 faster and better.

[0062] From the perspective of structural strength, the deepest depth h of the groove 10 is no more than 75% of the diameter D of the circumscribed circle 100 of the cross-section 1 of the special-shaped cross-section fiber. The bottom of the groove 10 is not likely to become a weak point of the structure itself, and is not likely to tear under the action of relevant stress, thereby better maintaining the original shape of the groove 10.

[0063] In some embodiments, in the special-shaped cross-section fiber, the width w of the widest part of the groove 10 may be not less than 15% of the diameter D of the circumscribed circle 100 of the cross-section 1 of the special-shaped cross-section fiber (that is, w / D ≥ 15%), and w / D may specifically be 15% to 100%, for example, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100% or a range consisting of any two of them, which can further improve the structural strength and other performance of the non-woven fabric.

[0064] Among them, the w / D of the special-shaped cross-section fibers in the fine fiber layer can be the same as or different from the w / D of the special-shaped cross-section fibers in the coarse fiber layer, and the w / D of the special-shaped cross-section fibers in the fine fiber layer can specifically be greater than, equal to or less than the w / D of the special-shaped cross-section fibers in the coarse fiber layer.

[0065] In some embodiments, in the special-shaped cross-section fiber, the deepest depth h of the groove 10 thereof can be no greater than 75% of the diameter D of the circumscribed circle 100 of the cross-section 1 of the special-shaped cross-section fiber (i.e., h / D ≤ 75%), and h / D can specifically be 5% to 75%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or a range consisting of any two thereof, which can further improve the structural strength and other properties of the non-woven fabric. Among them, the h / D of the special-shaped cross-section fibers in the fine fiber layer can be the same as or different from the h / D of the special-shaped cross-section fibers in the coarse fiber layer, and the h / D of the special-shaped cross-section fibers in the fine fiber layer can specifically be greater than, equal to, or less than the h / D of the special-shaped cross-section fibers in the coarse fiber layer.

[0066] The width w at the widest point of the groove 10 refers to the distance between the two side walls of the widest part of the groove 10, that is, the width w at the widest point of the groove 10 refers to the maximum straight-line distance between the two side walls constituting the groove 10. Specifically, the groove 10 has two side walls, which are respectively located on opposite sides of the groove 10 (that is, one side wall is located on one side of the groove 10 and the other side wall is located on the other side of the groove 10). The length of each of the two side walls in the length direction (axial direction) of the special-shaped cross-section fiber is equal to the length of the special-shaped cross-section fiber, wherein the maximum distance between the two side walls in the direction perpendicular to the length direction of the special-shaped cross-section fiber is the width w at the widest point of the groove 10.

[0067] For example, referring to Figures 1 to 14, the widest part of the groove 10 is the opening of the groove 10. At this time, the width w of the widest part of the groove 10 can specifically refer to the straight-line distance between the two end points of the outermost edge of the cross-sectional contour line of the two side walls constituting the groove 10, that is, in the cross-section 1 of the special-shaped cross-section fiber (the cross-section 1 is perpendicular to the axial direction of the special-shaped cross-section fiber), the straight-line distance between the end points of the two side walls surrounding the groove 10 at the opening of the groove 10 is the width w of the widest part of the groove 10.

[0068] For example, referring to FIG. 15 , the widest portion of the groove is located inside the groove 10 . In this case, the width w of the widest portion of the groove 10 is the distance between the two side walls of the groove 10 at the widest portion.

[0069] In addition, continuing to refer to Figures 1 to 15, the deepest depth of the groove 10 (i.e., the maximum depth of the groove 10) h refers to the maximum vertical distance between the bottom of the groove 10 (the bottom surface of the groove away from its opening) and the connecting line of the endpoints on opposite sides of the opening of the groove 10, wherein, in the cross-section 1 of the special-shaped cross-section fiber (the cross-section 1 is perpendicular to the axial direction of the special-shaped cross-section fiber), the straight line between the endpoints at the groove opening of the two side walls of the groove 10 is the above-mentioned connecting line.

[0070] It can be understood that the above-mentioned straight lines, connecting lines and outer contour lines are used to illustrate the width w of the widest part of the groove 10 and the depth h of the deepest part of the groove 10. They are all virtual lines and not physical structures.

[0071] Specifically, the shape of the cross section 1 of the above-mentioned special-shaped cross-section fiber may include a heart shape (as shown in Figure 4), a dumbbell shape, a crescent shape (as shown in Figure 6), a crescent shape (as shown in Figure 13), an incomplete circular ring, an incomplete circle, a multi-leaf clover shape, a polygon, an incomplete polygon, a character shape or a plum blossom shape, but is not limited to these, and may also be other regular or irregular shapes.

[0072] Among them, the central angle corresponding to the outer circle arc of the incomplete circular ring is smaller than the central angle corresponding to the outer circle arc of its complete concentric circular ring. For example, the incomplete circular ring includes a semicircular ring (that is, the central angle corresponding to the outer circle arc of the incomplete circular ring is 1 / 2 of the central angle corresponding to the outer circle arc of its complete concentric circular ring), or the incomplete circular ring as shown in Figure 15.

[0073] Among them, the central angle α of the incomplete circle (including sector, arc and open circle) is less than 360°. For example, the incomplete circle includes a seven-eighths circle (that is, its central angle α accounts for seven-eighths of 360°) or an open circle as shown in Figure 11.

[0074] Illustratively, the multi-leaf clover shape includes a three-leaf clover shape or a four-leaf clover shape.

[0075] Exemplarily, polygons include quadrilaterals (as shown in FIG9 ), pentagons or hexagons (as shown in FIG8 ), etc., and may also include polygons, such as triangular stars, quadrangular stars (as shown in FIG1 ), pentagrams, hexagons, octagonal stars or hexagonal stars (as shown in FIG10 and FIG12 ), etc.

[0076] Exemplarily, the incomplete polygon includes a polygon with missing corners, such as a rectangle with missing corners (as shown in FIG. 3 ).

[0077] Exemplarily, the character shapes include a cross shape (as shown in FIG7 ), a double cross shape, an I-shape, a M-shape, a wood-shape, a C-shape, an E-shape, an F-shape, a G-shape, an H-shape, a J-shape, a K-shape, an L-shape, an M-shape, an N-shape, an S-shape, a T-shape (as shown in FIG2 ), a U-shape (as shown in FIG14 ), a V-shape, a W-shape (as shown in FIG5 ), an X-shape, a Y-shape or a Z-shape.

[0078] Exemplarily, the plum blossom shape includes a four-petal plum blossom shape, a five-petal plum blossom shape, or a six-petal plum blossom shape.

[0079] Generally, the shapes of the profiled cross-section fibers in the fine fiber layer and the profiled cross-section fibers in the coarse fiber layer can be the same or different. Furthermore, the fine fiber layer may include a plurality of profiled cross-section fibers, which may have the same or different shapes, and the coarse fiber layer may include a plurality of profiled cross-section fibers, which may also have the same or different shapes.

[0080] In addition, in the above-mentioned non-woven fabric, the linear density of the main fibers of the coarse fiber layer is greater than the linear density of the main fibers of the fine fiber layer, that is, the linear density of the circular cross-section fibers and the irregular cross-section fibers in the coarse fiber layer is greater than the linear density of the circular cross-section fibers in the fine fiber layer, and both are greater than the linear density of the irregular cross-section fibers in the fine fiber layer.

[0081] In some embodiments, the difference between the linear density of the main fibers in the coarse fiber layer and the linear density of the main fibers in the fine fiber layer can be 0.1 dtex to 0.7 dtex, for example, 0.1 dtex, 0.2 dtex, 0.3 dtex, 0.4 dtex, 0.5 dtex, 0.6 dtex, 0.7 dtex, or a range consisting of any two thereof. Specifically, the difference between the linear density of the main fibers in the coarse fiber layer and the linear density of the main fibers in the fine fiber layer can both be within the above range (0.1 dtex to 0.7 dtex).

[0082] Exemplarily, the difference in linear density between the irregular cross-section fibers in the coarse fiber layer and the irregular cross-section fibers (or circular cross-section fibers) in the fine fiber layer can be 0.1dtex to 0.7dtex, for example, 0.1dtex, 0.2dtex, 0.3dtex, 0.4dtex, 0.5dtex, 0.6dtex, 0.7dtex or a range consisting of any two of them.

[0083] For example, the difference in linear density between the circular cross-section fibers in the coarse fiber layer and the circular cross-section fibers (or special-shaped cross-section fibers) in the fine fiber layer can be 0.1dtex to 0.7dtex, for example, 0.1dtex, 0.2dtex, 0.3dtex, 0.4dtex, 0.5dtex, 0.6dtex, 0.7dtex or a range consisting of any two of them.

[0084] In some embodiments, the linear density of the main fibers of the fine fiber layer can be less than or equal to 0.4 dtex, for example, less than or equal to 0.3 dtex, that is, in the fine fiber layer, the linear density of the circular cross-section fibers is less than or equal to 0.4 dtex, for example, less than or equal to 0.3 dtex, and the linear density of the irregular cross-section fibers is less than or equal to 0.4 dtex, for example, less than or equal to 0.3 dtex.

[0085] Exemplarily, the linear density of the main fibers (circular cross-section fibers, special-shaped cross-section fibers) of the fine fiber layer can be 0.05dtex, 0.06dtex, 0.08dtex, 0.1dtex, 0.13dtex, 0.15dtex, 0.18dtex, 0.2dtex, 0.23dtex, 0.25dtex, 0.28dtex, 0.3dtex, 0.33dtex, 0.35dtex, 0.38dtex, 0.4dtex or a range consisting of any two of them.

[0086] In the fine fiber layer, the linear density of the circular cross-section fibers and the irregular cross-section fibers may be the same or different. Specifically, the linear density of the circular cross-section fibers may be greater than, equal to, or less than the linear density of the irregular cross-section fibers.

[0087] In some embodiments, the linear density of the main fibers of the coarse fiber layer can be 0.4 dtex to 1.0 dtex, that is, in the coarse fiber layer, the linear density of the circular cross-section fibers is 0.4 dtex to 1.0 dtex, and the linear density of the special-shaped cross-section fibers is 0.4 dtex to 1.0 dtex.

[0088] For example, in the coarse fiber layer, the linear density of the main fibers (circular cross-section fibers, special-shaped cross-section fibers) can be 0.4 dtex, 0.5 dtex, 0.6 dtex, 0.7 dtex, 0.8 dtex, 0.9 dtex, 1 dtex or a range consisting of any two of them.

[0089] In the coarse fiber layer, the linear density of the circular cross-section fibers and the irregular cross-section fibers may be the same or different. Specifically, the linear density of the circular cross-section fibers may be greater than, equal to, or less than the linear density of the irregular cross-section fibers.

[0090] Furthermore, in the fine fiber layer, the linear density of the binder fibers may be less than or equal to 0.4 dtex. The linear density of the binder fibers may be the same as or different from the linear density of the main fibers (shaped cross-section fibers, circular cross-section fibers). Specifically, the linear density of the binder fibers may be greater than, equal to, or less than the linear density of the main fibers (shaped cross-section fibers, circular cross-section fibers).

[0091] Illustratively, the linear density of the bonding fibers in the fine fiber layer may be 0.05 dtex, 0.08 dtex, 0.1 dtex, 0.13 dtex, 0.15 dtex, 0.18 dtex, 0.2 dtex, 0.23 dtex, 0.25 dtex, 0.28 dtex, 0.3 dtex, 0.33 dtex, 0.35 dtex, 0.38 dtex, 0.4 dtex, or a range consisting of any two thereof.

[0092] Furthermore, the linear density of the binder fibers in the coarse fiber layer may be greater than the linear density of the binder fibers in the fine fiber layer.

[0093] In some embodiments, in the coarse fiber layer, the linear density of the bonding fibers can be 0.4 dtex to 1.8 dtex, for example, 0.4 dtex, 0.5 dtex, 0.6 dtex, 0.7 dtex, 0.8 dtex, 0.9 dtex, 1.0 dtex, 1.2 dtex, 1.3 dtex, 1.5 dtex, 1.7 dtex or a range consisting of any two of them.

[0094] Among them, in the coarse fiber layer, the linear density of the bonding fiber can be the same as or different from the linear density of the main fiber (irregular cross-section fiber, circular cross-section fiber), and the linear density of the bonding fiber can specifically be greater than, equal to or less than the linear density of the main fiber (irregular cross-section fiber, circular cross-section fiber).

[0095] In addition, in the fine fiber layer, the ratio of the mass of the special-shaped cross-section fibers to the mass of the main fibers (i.e., the mass proportion of the special-shaped cross-section fibers in the main fibers) can be 10% to 90%, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or a range consisting of any two of them.

[0096] In addition, in the fine fiber layer, the ratio of the mass of the circular cross-section fibers to the mass of the trunk fibers (i.e., the mass proportion of the circular cross-section fibers in the trunk fibers) is 10% to 90%, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or a range consisting of any two of them.

[0097] In addition, in the fine fiber layer, the mass percentage of the trunk fibers (i.e., the mass proportion of the trunk fibers in the fine fiber layer) is 60% to 80%, that is, the ratio of the total mass of the trunk fibers in the fine fiber layer (the sum of the mass of the circular cross-section fibers and the irregular cross-section fibers) to the total mass of the fine fiber layer (the sum of the total mass of the trunk fibers and the mass of the bonding fibers) is 60% to 80%, for example, 60%, 63%, 65%, 68%, 70%, 73%, 75%, 78%, 80% or a range consisting of any two of them.

[0098] In addition, in the fine fiber layer, the mass percentage of the bonding fiber (i.e., the mass proportion of the bonding fiber in the fine fiber layer) can be 20% to 40%, for example, 20%, 22%, 25%, 27%, 30%, 32%, 35%, 37%, 40% or a range consisting of any two of them.

[0099] In addition, in the fine fiber layer, the length of the main fibers can be 1 mm to 3 mm, that is, the length of the circular cross-section fibers can be 1 mm to 3 mm, and the length of the irregular cross-section fibers can be 1 mm to 3 mm.

[0100] Exemplarily, in the fine fiber layer, the length of the main fibers (circular cross-section fibers, special-shaped cross-section fibers) can be 1 mm, 1.3 mm, 1.5 mm, 1.8 mm, 2 mm, 2.3 mm, 2.5 mm, 2.8 mm, 3 mm or a range consisting of any two of them.

[0101] In the fine fiber layer, the lengths of the circular cross-section fibers and the irregular cross-section fibers may be the same or different. Specifically, the length of the circular cross-section fibers may be greater than, equal to, or less than the length of the irregular cross-section fibers.

[0102] Furthermore, in the fine fiber layer, the length of the bonding fibers may be 1 mm to 3 mm, for example, 1 mm, 1.3 mm, 1.5 mm, 1.8 mm, 2 mm, 2.3 mm, 2.5 mm, 2.8 mm, 3 mm, or any two thereof.

[0103] Among them, in the fine fiber layer, the length of the bonding fiber can be the same as or different from the length of the main fiber (special-shaped cross-section fiber, circular cross-section fiber), and the length of the bonding fiber can specifically be greater than, equal to or less than the length of the main fiber (special-shaped cross-section fiber, circular cross-section fiber).

[0104] In addition, in the coarse fiber layer, the ratio of the mass of the special-shaped cross-section fibers to the mass of the main fibers can be 10% to 60%, for example, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60% or a range consisting of any two of them.

[0105] In addition, in the coarse fiber layer, the mass percentage of the trunk fibers can be 60% to 80%, that is, the ratio of the total mass of the trunk fibers in the coarse fiber layer (the sum of the mass of the circular cross-section fibers and the special-shaped cross-section fibers) to the total mass of the coarse fiber layer (the sum of the total mass of the trunk fibers and the mass of the bonding fibers) is 60% to 80%, for example, 60%, 63%, 65%, 68%, 70%, 73%, 75%, 78%, 80% or a range consisting of any two of them.

[0106] In addition, in the coarse fiber layer, the mass percentage of the bonding fiber can be 20% to 40%, for example, 20%, 22%, 25%, 27%, 30%, 32%, 35%, 37%, 40% or a range consisting of any two of them.

[0107] In addition, in the coarse fiber layer, the length of the main fibers can be 1 mm to 6 mm, that is, the length of the circular cross-section fibers can be 1 mm to 6 mm, and the length of the special-shaped cross-section fibers can be 1 mm to 6 mm.

[0108] Exemplarily, in the coarse fiber layer, the length of the main fibers (circular cross-section fibers, special-shaped cross-section fibers) can be 1 mm, 1.3 mm, 1.5 mm, 1.8 mm, 2 mm, 2.3 mm, 2.5 mm, 2.8 mm, 3 mm, 3.3 mm, 3.5 mm, 3.8 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm or a range consisting of any two of them.

[0109] In the coarse fiber layer, the lengths of the circular cross-section fibers and the irregular cross-section fibers may be the same or different. Specifically, the length of the circular cross-section fibers may be greater than, equal to, or less than the length of the irregular cross-section fibers.

[0110] In addition, in the coarse fiber layer, the length of the bonding fiber can be 1 mm to 6 mm, for example, 1 mm, 1.3 mm, 1.5 mm, 1.8 mm, 2 mm, 2.3 mm, 2.5 mm, 2.8 mm, 3 mm, 3.3 mm, 3.5 mm, 3.8 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm or a range consisting of any two of them.

[0111] Among them, in the coarse fiber layer, the length of the bonding fiber can be the same as or different from the length of the main fiber (special-shaped cross-section fiber, circular cross-section fiber), and the length of the bonding fiber can specifically be greater than, equal to or less than the length of the main fiber (special-shaped cross-section fiber, circular cross-section fiber).

[0112] The linear density of the aforementioned main fibers and the linear density of the binder fibers refer to average linear densities, which can be measured by conventional methods in the art, for example, according to GB / T 14335-2008, Test Method for Linear Density of Chemical Staple Fibers. The length of the aforementioned main fibers and the length of the binder fibers refer to average lengths, which can be measured by conventional methods in the art, for example, according to GB / T 14336-2008, Test Method for Length of Chemical Staple Fibers.

[0113] In addition, the surface density of the coarse fiber layer may be greater than the surface density of the fine fiber layer, and the difference between the surface density of the coarse fiber layer and the surface density of the fine fiber layer may be no greater than (i.e., less than or equal to) 20 g / m 2 , for example 1g / m 2 , 2g / m 2 , 3g / m 2 , 4g / m 2 、 5g / m 2 , 6g / m 2 , 7g / m2 , 8g / m 2 , 9g / m 2 , 10g / m 2 , 11g / m 2 , 12g / m 2 , 13g / m 2 , 14g / m 2 , 15g / m 2 , 16g / m 2 , 17g / m 2 , 18g / m 2 , 19g / m 2 , 20g / m 2 or a range consisting of any two of them.

[0114] In some embodiments, the surface density of the coarse fiber layer can be 4 to 24 g / m 2 , for example 4g / m 2 , 5g / m 2 , 8g / m 2 , 10g / m 2 , 13g / m 2 , 15g / m 2 , 16g / m 2 , 18g / m 2 , 20g / m 2 , 22g / m 2 , 24g / m 2 or a range consisting of any two of them.

[0115] In some embodiments, the area density of the fine fiber layer may be greater than 0 and not greater than 8 g / m 2 The surface density of the fine fiber layer is, for example, 1 g / m 2 , 1.5g / m 2 , 2g / m 2 , 2.5g / m 2 , 3g / m 2 3.5g / m 2 , 4g / m 2 4.5g / m 2 , 5g / m 2 , 5.5g / m 2 , 6g / m 2 , 6.5g / m 2 , 7g / m 2 , 7.5g / m 2 , 8g / m 2 or a range consisting of any two of them.

[0116] Furthermore, to ensure that the main fibers in the nonwoven fabric do not, or substantially do not, undergo morphological changes due to melting or softening during processing when the binder fibers melt and soften, the softening point of the main fibers is greater than that of the binder fibers. To better maintain the morphology of the main fibers, the difference between the softening points of the main fibers and the binder fibers is preferably greater than or equal to 20°C.

[0117] That is, in the coarse fiber layer, the difference in softening point between the main fibers (circular cross-section fibers, special-shaped cross-section fibers) and the bonding fibers can be greater than or equal to 20°C, the softening point of the circular cross-section fibers and the softening point of the special-shaped cross-section fibers can be the same or different, and the softening point of the circular cross-section fibers can specifically be greater than, equal to, or less than the softening point of the special-shaped cross-section fibers; in the fine fiber layer, the difference in softening point between the main fibers (circular cross-section fibers, special-shaped cross-section fibers) and the bonding fibers can be greater than or equal to 20°C, the softening point of the circular cross-section fibers and the softening point of the special-shaped cross-section fibers can be the same or different, and the softening point of the circular cross-section fibers can specifically be greater than, equal to, or less than the softening point of the special-shaped cross-section fibers.

[0118] In some embodiments, in the coarse fiber layer or the fine fiber layer, the difference between the softening point of the main fiber (circular cross-section fiber or special-shaped cross-section fiber) and the softening point of the bonding fiber can be specifically 20 to 280°C, for example, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 90°C, 95°C, 100°C, 110°C, 120°C , 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, 160℃, 165℃, 170℃, 180℃, 190℃, 195℃, 200℃, 205℃, 210℃, 220℃, 230℃, 240℃, 250℃, 252℃, 255℃, 260℃, 265℃, 270℃, 275℃, 280℃ or a range consisting of any two of them.

[0119] In some embodiments, in the coarse fiber layer or the fine fiber layer, the softening point of the main fiber (circular cross-section fiber or special-shaped cross-section fiber) can be 190°C to 400°C, for example, 190°C, 200°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C, 400°C or a range consisting of any two of them.

[0120] Specifically, in the above-mentioned fine fiber layer and coarse fiber layer, the softening point of the bonding fiber can be greater than or equal to 120°C, the softening points of the bonding fibers in the fine fiber layer and the coarse fiber layer can be the same or different, and the softening point of the bonding fiber in the fine fiber layer can specifically be greater than, equal to or less than the softening point of the bonding fiber in the coarse fiber layer.

[0121] In some embodiments, in the coarse fiber layer or the fine fiber layer, the softening point of the bonding fiber can be 120°C to 230°C, for example, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C or a range consisting of any two of them.

[0122] In specific implementation, the softening point of the backbone fiber and the binder fiber can be measured using a differential scanning calorimeter (DSC). Specifically, a differential scanning calorimeter (DSC) is used to measure the differential scanning calorimetry curve of the fiber by programmed temperature rise, and the starting temperature T at which the melting endothermic peak in the obtained curve begins to deviate from the baseline is used. i To characterize the softening point of the fiber (as shown in Figure 16), the specific test method can refer to GBT 19466.3-2004 (Plastics Differential Scanning Calorimetry (DSC) Part 3: Determination of melting and crystallization temperatures and enthalpy).

[0123] In some embodiments, the binder fibers may include one or more of undrawn polyester fibers, polyvinylidene fluoride fibers (PVDF), polyamide fibers, polyolefin fibers, copolyester fibers, and copolyamide fibers.

[0124] Alternatively, the undrawn polyester fiber may include polyethylene terephthalate (PET) and / or polybutylene terephthalate (PBT).

[0125] Alternatively, the polyolefin fiber may include one or more of polyethylene (PE), polypropylene (PP), polyvinyl chloride, polystyrene, polyethylene / polypropylene sheath-core fiber, polyethylene / polyethylene terephthalate sheath-core fiber, polyethylene / polybutylene terephthalate sheath-core fiber, and the like.

[0126] Specifically, the bonding fiber may include a bicomponent fiber formed by two fiber materials, the two fiber materials being, for example, polyethylene and polypropylene, or polyethylene and polyethylene terephthalate, or polyethylene and polybutylene terephthalate. The bicomponent fiber may include parallel type, skin-core type, multi-core type composite fiber, island type composite fiber and other structures, and the bicomponent fiber of the corresponding structure may be prepared according to conventional processes in the art.

[0127] Among them, the sheath-core fiber has a sheath-core structure, that is, among the two fiber materials that form the two-component sheath-core fiber, one fiber material forms the core layer, and the other fiber material forms the sheath layer existing on the surface of the core layer. The sheath layer can be specifically wrapped around the circumference of the core layer, thereby forming a sheath-core structure.

[0128] For example, the bonding fiber may include a PE / PP bicomponent fiber, which may specifically be a PE / PP bicomponent core-sheath fiber (i.e., the above-mentioned polyethylene / polypropylene core-sheath fiber). The PE / PP bicomponent fiber includes a core layer and a skin layer present on the surface of the core layer. The skin layer may specifically be wrapped around the circumference of the core layer. The core layer includes PE, and the skin layer includes PP.

[0129] Alternatively, the copolyester fiber may include at least one of a polyethylene terephthalate copolymer fiber (CoPET) or a polybutylene terephthalate copolymer fiber (CoPBT). Alternatively, the copolyamide fiber is formed by copolymerizing monomers of at least two polyamides, such as one or more of polyamide 6 (PA6), polyamide 11 (PA11), polyamide 12 (PA12), polyamide 66 (PA66), polyamide 69 (PA69), polyamide 610 (PA610), polyamide 612 (PA612), and polyamide 1010 (PA1010). That is, the copolyamide fiber may be a copolymer of monomers of at least two of these polyamides.

[0130] Specifically, the copolyamide fiber may include at least one of binary copolyamide, ternary copolyamide, or tetrapolyamide.

[0131] In some embodiments, the copolyamide fibers may include PA6 / 6 (a binary copolyamide 6 / 6 formed by copolymerizing monomers of polyamide 6 with different molecular weights or polymerization degrees), PA6 / 66 (a binary copolyamide 6 / 66 formed by copolymerizing monomers of polyamide 6 and monomers of PA66), PA6 / 66 / 12 (a ternary copolyamide 6 / 66 / 12 formed by copolymerizing monomers of polyamide 6, polyamide 66, and polyamide 12), PA6 / 66 / 69 (a binary copolyamide 6 / 66 formed by copolymerizing monomers of polyamide 6, polyamide 66, and polyamide 12), and PA6 / 66 / 69. (a ternary copolymerized polyamide 6 / 66 / 69 formed by copolymerizing the monomers of polyamide 6, polyamide 66 and polyamide 69), PA6 / 66 / 610 (a ternary copolymerized polyamide 6 / 66 / 610 formed by copolymerizing the monomers of polyamide 6, polyamide 66 and polyamide 610), PA6 / 66 / 612 (a ternary copolymerized polyamide 6 / 66 / 612 formed by copolymerizing the monomers of polyamide 6, polyamide 66 and polyamide 612), PA6 / 66 / 1010 (a ternary copolymerized polyamide 6 / 66 / 1010 formed by copolymerizing the monomers of polyamide 6, polyamide 66 and polyamide 1010), PA6 / 612 / 12 (a ternary copolymerized polyamide 6 / 612 / 12 formed by copolymerizing the monomers of polyamide 6, polyamide 612 and polyamide 12), PA6 / 610 / 12 (a ternary copolymerized polyamide 6, polyamide 610 and polyamide 12). One or more of PA6 / 66 / 69 / 12 (a tetrapolymer formed by copolymerizing a monomer of polyamide 6, a monomer of polyamide 66, a monomer of polyamide 69 and a monomer of polyamide 12), PA6 / 66 / 11 / 12 (a tetrapolymer formed by copolymerizing a monomer of polyamide 6, a monomer of polyamide 66, a monomer of polyamide 11 and a monomer of polyamide 12), etc.

[0132] Specifically, the materials of the bonding fibers in the fine fiber layer and the bonding fibers in the coarse fiber layer may be the same or different.

[0133] In some embodiments, the above-mentioned main fibers (circular cross-section fibers, special-shaped cross-section fibers) may include one or more of polyester fibers, polyolefin fibers, polyamide fibers, polyimide fibers (PI), polytetrafluoroethylene fibers (PTFE), polyphenylene sulfide fibers (PPS), polyetheretherketone fibers, polyacrylonitrile fibers (PAN), polycarbonate fibers, and aramid fibers.

[0134] Alternatively, the polyester fiber may include one or more of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate, and polyisophthalic acid resin.

[0135] Alternatively, the polyolefin fiber may include one or more of polyethylene, polypropylene (PP), polyvinyl chloride, polystyrene, polyethylene / polypropylene sheath-core fiber, polyethylene / polyethylene terephthalate sheath-core fiber, and polyethylene / polybutylene terephthalate sheath-core fiber.

[0136] Alternatively, the polyamide fiber may include polyamide 66 (PA66).

[0137] In the above-mentioned fine fiber layer and coarse fiber layer, the material of the circular cross-section fibers can be the same as or different from the material of the special-shaped cross-section fibers; the material of the main fibers in the fine fiber layer can be the same as or different from the material of the main fibers in the coarse fiber layer. For example, the material of the circular cross-section fibers in the fine fiber layer can be the same as or different from the material of the circular cross-section fibers in the coarse fiber layer, and the material of the special-shaped cross-section fibers in the fine fiber layer can be the same as or different from the material of the special-shaped cross-section fibers in the coarse fiber layer.

[0138] In addition, the thickness of the non-woven fabric can be less than or equal to 30 μm, and while maintaining a relatively thin thickness, it can also have strong structural strength. In some embodiments, the thickness of the non-woven fabric can specifically be 5 μm to 30 μm, for example, 5 μm, 8 μm, 10 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 18 μm, 20 μm, 22 μm, 23 μm, 25 μm, 28 μm, 30 μm or a range consisting of any two thereof. While maintaining a relatively thin thickness, the non-woven fabric also has strong structural strength and other properties, and is suitable for battery separators, taking into account performance such as improving the energy density and safety of the battery.

[0139] In addition, the surface density of the non-woven fabric can be 4g / m 2 ~25g / m 2 , for example 4g / m 2 , 7g / m 2 , 10g / m 2 , 13g / m 2 , 15g / m 2 , 18g / m 2 , 20g / m 2 , 23g / m 2 , 25g / m 2 or a range consisting of any two of them.

[0140] In addition, the density of the nonwoven fabric can be 0.5g / cm 3 ~0.9g / cm 3 , for example 0.5g / cm 3 , 0.6g / cm 3 , 0.7g / cm 3 , 0.8g / cm 3 , 0.9g / cm3 or a range consisting of any two of them.

[0141] The above-mentioned non-woven fabric can be produced by conventional methods in the art, and is not particularly limited thereto. For example, raw materials for forming non-woven fabrics (such as the above-mentioned main fibers and binder fibers, etc.) are used to produce non-woven base paper using conventional equipment in the art, such as an inclined wire paper machine, and then the resulting formed fiber base paper is subjected to a hot calendering treatment using a hot press, such as a steel roller / soft roller or a steel roller / steel roller combination, and the hot calendering treatment temperature is, for example, 100°C to 300°C. After the hot calendering treatment, the non-woven fabric with significantly improved mechanical strength as described in the present invention can be obtained.

[0142] The diaphragm provided by the embodiment of the present invention includes the above-mentioned non-woven fabric, that is, the diaphragm is a non-woven fabric diaphragm, which has at least the following advantages: (1) The diaphragm has strong structural strength and can maintain a relatively thin thickness, thereby taking into account the improvement of the safety, cycle life and energy density of electrochemical energy storage devices such as lithium-ion batteries using the diaphragm; (2) The diaphragm has good wettability to the electrolyte, so that it has high liquid absorption and liquid retention rate in non-solid-state batteries (containing electrolyte), which is conducive to the full infiltration and uniform distribution of the electrolyte in the battery cell, reducing the interface resistance, thereby improving the battery's rate performance, discharge capacity and service life; (3) The diaphragm can be a diaphragm composited with components such as a solid electrolyte (such as an electrolyte membrane composited with a solid electrolyte), which can improve the filling density and loading amount of components such as the solid electrolyte in the non-woven fabric, improve the interface contact properties of materials such as the solid electrolyte, and optimize battery performance.

[0143] Generally, a battery includes a positive electrode sheet and a negative electrode sheet, and a separator is located between the positive electrode sheet and the negative electrode sheet to separate the positive electrode sheet from the negative electrode sheet.

[0144] The separators of the embodiments of the present invention can be used in non-solid-state batteries (such as liquid batteries and semi-solid-state batteries) as well as solid-state batteries. When used in semi-solid-state batteries or solid-state batteries, they also function as electrolytes, that is, as electrolyte membranes, replacing electrolytes. Of course, in semi-solid-state batteries, electrolytes are generally still required.

[0145] Taking the application of diaphragms in non-all-solid-state batteries as an example, the pore size of the coarse fiber layer in the non-woven fabric is larger than that of the fine fiber layer. The fine fiber layer forms a liquid-absorbing layer, and the coarse fiber layer forms a liquid-retaining layer, thereby improving the diaphragm's liquid absorption and liquid retention rate for the electrolyte. For example, a non-woven fabric with a double-layer structure (fine fiber layer-coarse fiber layer) forms a "liquid-absorbing layer-liquid-retaining layer" composite structure, a non-woven fabric with a three-layer structure (fine fiber layer-coarse fiber layer-fine fiber layer) with a fine fiber layer on the surface forms a "liquid-absorbing layer-liquid-retaining layer-liquid-absorbing layer" composite structure, and a non-woven fabric with a three-layer structure (coarse fiber layer-fine fiber layer-coarse fiber layer) with a coarse fiber layer on the surface forms a "liquid-retaining layer-liquid-absorbing layer-liquid-retaining layer" composite structure. Through the synergistic effect of the fine fiber layer with fine pores and the coarse fiber layer with loose pores, a capillary pressure difference is formed between the layers, which plays the role of liquid absorption, liquid conduction and liquid retention.

[0146] Specifically, the high specific surface area of ​​the irregular cross-section fine fibers (i.e., the irregular cross-section fibers in the fine fiber layer) increases the liquid absorption rate of the fine fiber layer for the electrolyte solution, especially when the surface of the irregular cross-section fibers has grooves 10. The capillary force generated by the fine grooves 10 on the fiber surface allows the electrolyte solution to quickly infiltrate the surface and interior of the fine fiber layer through wicking, making it very easy for the electrolyte components to enter between the fibers. The pores communicating between the inside and outside of the fiber layer and the fine grooves 10 on the fiber surface provide channels for the migration of the electrolyte. Therefore, the fine fiber layer has a high liquid absorption efficiency and can transport the electrolyte to the adjacent coarse fiber layer. There are pores between the fibers that can form a capillary effect. After the electrolyte is quickly transferred to the coarse fiber layer, the electrolyte between the fibers is mainly held by a large amount of microporous capillary attraction. Therefore, inside the battery cell, the electrolyte can be continuously and effectively transported and diffused in the "liquid absorption layer" and "liquid retention layer" of each layer of non-woven fabric separator that are adjacent due to winding or lamination by means of capillary effect, so that the electrolyte is evenly distributed from the outside to the inside of the battery cell, building a fast channel for the transfer of ions (such as lithium ions).

[0147] Non-woven fabric separators with high liquid absorption and retention rates bring good wettability, which can significantly improve the performance of batteries (such as lithium-ion batteries). For example, it can reduce the internal resistance of the battery. Reducing the battery interface impedance is conducive to improving the utilization efficiency of active substances, thereby increasing battery capacity and improving discharge rate characteristics. At the same time, the improvement of the wetting effect can also shorten the electrolyte infiltration time and save production costs.

[0148] In some embodiments, the above-mentioned diaphragm may also include a coating, which is provided on at least one area selected from the surface of the non-woven fabric and at least a portion (all or part) of the pores present in the non-woven fabric, that is, the coating may be located on the surface of the non-woven fabric, or filled in the pores in the non-woven fabric, or partially located on the surface of the non-woven fabric and partially filled in the pores in the non-woven fabric.

[0149] That is, the above-mentioned diaphragm may also include a component compounded with the non-woven fabric (used to form the above-mentioned coating), and the non-woven fabric serves as the skeleton of the diaphragm to carry the component. The component can be specifically filled into the interior of the non-woven fabric, for example, penetrating into the fiber surface, gaps, pores or concave and convex structures inside the non-woven fabric. The component can also form a coating on the surface of the non-woven fabric (that is, the diaphragm may also include a coating located on the surface of the non-woven fabric).

[0150] Specifically, the coating may include components such as an electrolyte, for example, one or more solid electrolytes such as a polymer electrolyte, an oxide electrolyte, and a sulfide ceramic electrolyte. That is, the coating may be an electrolyte layer composited with a non-woven fabric, and the separator may be a solid electrolyte membrane composited with a non-woven fabric and a solid electrolyte. This solid electrolyte membrane can be applied to all-solid-state batteries or semi-solid-state batteries.

[0151] In specific implementation, the components used to be composited with the non-woven fabric (such as solid electrolytes, etc., hereinafter referred to as composite components) can be prepared into a coating slurry, and then the coating slurry is applied to the preset surface of the non-woven fabric, and after drying and other treatments, a coating is formed.

[0152] Fibers are the skeleton of non-woven fabrics. The morphology and arrangement of fibers in non-woven fabrics determine the pore structure inside the non-woven fabrics. The cross-section 1 of the special-shaped cross-section fibers is irregular in shape. By introducing special-shaped cross-section fibers into non-woven fabrics, the contact area between the non-woven fabric and the coating slurry is greatly increased, and the number and size of capillary pores inside the non-woven fabric can be controlled. At the same time, the specific surface area and capillary effect of the fibers and fiber webs in the non-woven fabrics are significantly increased, which is beneficial to enhance the absorption, transfer and retention of the components compounded with the non-woven fabrics by the non-woven fabrics, and optimize the performance of the non-woven fabric membranes.

[0153] In some embodiments, at least one surface layer of the non-woven fabric is a fine fiber layer, and the above-mentioned coating is at least located on the fine fiber layer, and / or, the fiber layer of at least one surface layer of the non-woven fabric is a coarse fiber layer, and the above-mentioned coating is at least located on the coarse fiber layer.

[0154] Specifically, the non-woven fabric has two opposite sides, one of which may be a fine fiber layer and the other side may be a coarse fiber layer (for example, the non-woven fabric has a double-layer structure of fine fiber layer-coarse fiber layer). In this case, the above-mentioned coating exists on the fine fiber layer on one side and / or the coarse fiber layer on the other side; or, the opposite sides of the non-woven fabric are both fine fiber layers (for example, the non-woven fabric has a three-layer structure of fine fiber layer-coarse fiber layer-fine fiber layer), that is, the surface layers on the opposite sides of the non-woven fabric are both fine fiber layers. In this case, the above-mentioned coating exists on at least one of the fine fiber layers on the opposite sides; or, the opposite sides of the non-woven fabric are both coarse fiber layers (for example, the non-woven fabric has a three-layer structure of coarse fiber layer-fine fiber layer-coarse fiber layer), that is, the surface layers on the opposite sides of the non-woven fabric are both coarse fiber layers. In this case, the above-mentioned coating exists on at least one of the coarse fiber layers on the opposite sides.

[0155] In general, when a thinner coating (such as an electrolyte layer) is required (such as when the above-mentioned diaphragm is applied to a non-all-solid-state battery), it is preferred that at least one side of the non-woven fabric has a fine fiber layer as the surface layer, and the coating is located on the fine fiber layer, that is, the coating (or diaphragm coating layer) is preferably compounded on the outer surface of the fine fiber layer of the non-woven fabric. For example, the non-woven fabric used can be a double-layer structure (fine fiber layer-coarse fiber layer), or a three-layer structure (fine fiber layer-coarse fiber layer-fine fiber layer) with a fine fiber layer as the surface layer. When the non-woven fabric has a three-layer structure with a fine fiber layer as the surface layer, the coating can be present on at least one of the fine fiber layers on opposite sides. The fine fiber layer has a larger specific surface area and a higher porosity. The slurry used to form the coating during the coating process can easily penetrate and fill it. At the same time, the special-shaped cross-section fibers in the fine fiber layer can also significantly increase the effective area of ​​contact and compounding with the coating material. By applying a small amount of coating on the outer surface of the fine fiber layer, a continuous coating can be formed to obtain an ultra-thin diaphragm.

[0156] When a high-load membrane (such as an electrolyte membrane) is required (such as when the above-mentioned membrane is applied to an all-solid-state battery), it is preferred that at least one side of the surface layer of the non-woven fabric is a coarse fiber layer, and the coating is located on the coarse fiber layer, that is, the coating is preferably compounded on the outer surface of the coarse fiber layer of the non-woven fabric. For example, the non-woven fabric used can be a double-layer structure (fine fiber layer-coarse fiber layer), or a three-layer structure with a coarse fiber layer as the surface layer (coarse fiber layer-fine fiber layer-coarse fiber layer). When the non-woven fabric is a three-layer structure with a coarse fiber layer as the surface layer, the above-mentioned coating can be present on at least one of the coarse fiber layers on its opposite sides.

[0157] Specifically, using the above-mentioned non-woven fabric, during the coating process, the coating slurry (such as a solid electrolyte slurry prepared using a solid electrolyte) can be embedded in the internal pores of the non-woven fabric through capillary action. When the irregular cross-section fibers in the non-woven fabric have grooves 10, the coating slurry will also be embedded in the fine grooves 10 on the surface of the irregular cross-section fibers. The strong wicking and capillary action help the coating slurry to spontaneously wet and aggregate on the fiber surface and / or transfer to the internal pores of the non-woven fabric, thereby greatly increasing the contact area between the non-woven fabric and the composite component (such as a solid electrolyte) and enhancing the adsorption and wrapping ability of the non-woven fabric for the composite component. It is beneficial to improve the filling density and loading amount of the composite components in the non-woven fabric, so that the composite components can be more fully and effectively filled in the non-woven fabric, thereby improving the interface contact problem of the composite components; at the same time, the strong bonding between the composite components and the non-woven fabric is achieved through the anchoring effect, and the coating slurry penetrates into the fiber surface, gaps, pores or concave and convex structures inside the non-woven fabric. After drying and curing, a meshing force is generated at the contact interface, thereby achieving high bonding strength between the composite components and the non-woven fabric, which is beneficial to reduce the solid / solid interface impedance between composite components such as solid electrolytes and non-woven fabric fibers, thereby effectively improving the battery's rate performance and other performance.

[0158] The battery provided in the embodiments of the present invention includes the aforementioned separator. As previously mentioned, the battery provided in the embodiments of the present invention can be a non-solid-state battery (such as a liquid battery or a semi-solid-state battery) or a solid-state battery. These batteries can be of conventional structures in the art and are not particularly limited thereto. By using the aforementioned separator, it is possible to improve both the electrochemical performance and cycle life of the battery.

[0159] Specifically, the battery includes a cell, the cell includes a positive electrode sheet and a negative electrode sheet, and a separator is spaced between the positive electrode sheet and the negative electrode sheet.

[0160] Specifically, the battery in the embodiment of the present invention may be a lithium-ion battery, but is not limited thereto.

[0161] The present invention is further described below through specific examples.

[0162] In the following examples and comparative examples, main fibers and binder fibers were used to make non-woven base paper using an inclined wire paper machine, and the obtained base paper was then hot-pressed and laminated to produce non-woven fabrics.

[0163] In Examples 1 to 15 and Comparative Example 1, the materials, softening points, fiber linear density, fiber length, fiber content (i.e., the mass percentage of the fiber in the non-woven fabric) of the main fibers (special-shaped cross-section fibers, circular cross-section fibers) and the bonding fibers used in each fiber layer (coarse fiber layer and fine fiber layer), the shape of the special-shaped cross-section fibers, and the perimeter coefficient X of the cross section of the special-shaped cross-section fibers were calculated. L, the number of grooves of the special-shaped cross-section fiber, the ratio of the width of the widest part of the groove to the diameter of the circumscribed circle of the cross-section of the special-shaped cross-section fiber (w / D), the ratio of the depth of the deepest part of the groove to the diameter of the circumscribed circle of the cross-section of the special-shaped cross-section fiber (h / D), the density of each fiber layer and other parameters are shown in Tables 1 to 9. The thickness of the non-woven fabric, the surface density of the non-woven fabric, the density of the non-woven fabric and the measured longitudinal tensile strength, transverse tensile strength, electrolyte climbing height and electrolyte absorption rate of the non-woven fabric are shown in Table 10.

[0164] Among them, the surface density of non-woven fabrics is measured in accordance with GB / T 451.2-2002; the thickness of non-woven fabrics is measured in accordance with GB / T 451.3-2002; the density of non-woven fabrics is the ratio of the surface density of the non-woven fabrics to the thickness of the non-woven fabrics; the tensile strength (transverse tensile strength and longitudinal tensile strength) of non-woven fabrics is measured in accordance with GB / T 12914-2008; the perimeter modulus of the cross section of special-shaped cross-section fibers is measured in accordance with FZ / T 50002-2013.

[0165] In the following embodiments, the cross-sectional shape (four-pointed star shape) of the irregular cross-sectional fibers in the fine fiber layer of Example 1, Example 6, Example 7, Example 9, Example 12, and Example 15 is shown in FIG1 , the cross-sectional shape (T-shape) of the irregular cross-sectional fibers in the coarse fiber layer of Example 1, Example 6, Example 7, Example 8, Example 11, and Example 14 is shown in FIG2 , the cross-sectional shape (rectangle with missing corners) of the irregular cross-sectional fibers in the fine fiber layer and the coarse fiber layer of Example 2 is shown in FIG3 , the cross-sectional shape (heart shape) of the irregular cross-sectional fibers in the fine fiber layer of Example 3 is shown in FIG4 , the cross-sectional shape (W shape) of the irregular cross-sectional fibers in the coarse fiber layer of Example 3 is shown in FIG5 , the cross-sectional shape (crescent shape) of the irregular cross-sectional fibers in the fine fiber layer of Example 4 is shown in FIG6 , and the cross-sectional shape of the irregular cross-sectional fibers in the coarse fiber layer of Example 4 is shown in FIG4 (cross-shaped) as shown in Figure 7, the cross-sectional shape of the irregular cross-sectional fibers in the coarse fiber layer of Example 5 (hexagonal) is shown in Figure 8, the cross-sectional shape of the irregular cross-sectional fibers in the fine fiber layer of Example 5 (quadrilateral) is shown in Figure 9, the cross-sectional shape of the irregular cross-sectional fibers in the fine fiber layer of Example 8 and the coarse fiber layer of Example 9 (hexagonal star) is shown in Figure 10, the cross-sectional shape of the irregular cross-sectional fibers of Example 10 (open circle) is shown in Figure 11, the cross-sectional shape of the irregular cross-sectional fibers in the fine fiber layer of Example 11 and the coarse fiber layer of Example 12 (hexagonal star) is shown in Figure 12, the cross-sectional shape of the irregular cross-sectional fibers in the fine fiber layer and coarse fiber layer of Example 13 (crescent-shaped) is shown in Figure 13, and the cross-sectional shape of the irregular cross-sectional fibers in the fine fiber layer of Example 14 and the coarse fiber layer of Example 15 (U-shaped) is shown in Figure 14.

[0166] Example 1

[0167] The nonwoven fabric of this embodiment has a double-layer structure (fine fiber layer-coarse fiber layer), and the fiber parameters of each layer are shown in Table 1.

[0168] Table 1

[0169] Example 2

[0170] The nonwoven fabric of this embodiment has a double-layer structure (fine fiber layer-coarse fiber layer), and the fiber parameters of each layer are shown in Table 2.

[0171] Table 2 Note: "PE / PP" in Table 2 indicates PE / PP two-component sheath-core fiber, with PE forming the core layer and PP forming the sheath layer.

[0172] Example 3

[0173] The nonwoven fabric of this embodiment has a double-layer structure (fine fiber layer-coarse fiber layer), and the fiber parameters of each layer are shown in Table 3.

[0174] Table 3

[0175] Example 4

[0176] The nonwoven fabric of this embodiment has a double-layer structure (fine fiber layer-coarse fiber layer), and the fiber parameters of each layer are shown in Table 4.

[0177] Table 4

[0178] Example 5

[0179] The non-woven fabric of Example 5 is a double-layer structure (fine fiber layer-coarse fiber layer), and the fiber parameters of each layer are shown in Table 5 (the surface of the special-shaped cross-section fibers in each fiber layer has no grooves).

[0180] Table 5

[0181] Example 6

[0182] The non-woven fabric of this embodiment 6 has the following three-layer structure: fine fiber layer-coarse fiber layer-fine fiber layer (that is, the coarse fiber layer is located between two fine fiber layers). The composition of its two fine fiber layers is the same as that of the fine fiber layer of embodiment 1, and its coarse fiber layer is the same as that of the coarse fiber layer of embodiment 1 (see Table 6 for details).

[0183] Table 6

[0184] Example 7

[0185] The non-woven fabric of this embodiment 7 has the following three-layer structure: coarse fiber layer-fine fiber layer-coarse fiber layer (that is, the fine fiber layer is located between two coarse fiber layers). The composition of its two coarse fiber layers is the same as that of the coarse fiber layer of embodiment 1, and its fine fiber layer is the same as that of the fine fiber layer of embodiment 1 (see Table 7 for details).

[0186] Table 7

[0187] Examples 8 to 15: The difference from Example 1 is that the shapes of the special-shaped cross-section fibers in the fine fiber layer and / or the coarse fiber layer are different, see Table 8 for details. Except for the differences shown in Table 8, the other conditions are the same as those in Example 1.

[0188] Table 8

[0189] Comparative Example 1

[0190] The non-woven fabric of Comparative Example 1 has a double-layer structure (fine fiber layer-coarse fiber layer), and the fiber parameters of each layer are shown in Table 9 (each fiber layer does not use special-shaped cross-section fibers).

[0191] Table 9

[0192] According to the following process, the non-woven fabrics of the above embodiments and comparative examples were used as samples to test their respective electrolyte climbing heights and electrolyte absorption rates (the composition of the electrolyte used was: ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 1:1, and the concentration of LiPF6 in the electrolyte was 1 mol / L):

[0193] (1) Test of the climbing height of the electrolyte on the sample: Cut the sample into a rectangular strip of 20 cm × 1 cm (i.e., its length is 20 cm and its width is 1 cm), fix one end of the obtained strip to be tested on a fixture perpendicular to the test bench, and immerse the strip vertically in the electrolyte solution in the culture dish. The immersion depth of the strip in the electrolyte is about 0.5 cm (i.e., the length of the part of the strip immersed in the electrolyte is 0.5 cm). After standing for 15 minutes, measure the climbing height of the electrolyte on the strip. Repeat the test 3 to 5 times and take the average value as the test result of the electrolyte climbing height (the greater the climbing height of the electrolyte on the strip, the faster the sample (non-woven fabric) absorbs the electrolyte). See Table 10;

[0194] (2) Test of electrolyte absorption rate: Weigh the mass of the sample before it is soaked in electrolyte, recorded as m1; spread a sample of approximately 40 mm × 40 mm in size and completely immerse it in the electrolyte. After standing in the electrolyte for 15 minutes, take it out and let it stand in the air for 2 minutes to remove excess electrolyte on the membrane surface, and then weigh it, recorded as m2. The electrolyte absorption rate is calculated using the following formula: Electrolyte absorption rate = (m2-m1) / m1×100%; repeat the test multiple times and take the average value as the final absorption rate test result, see Table 10.

[0195] Table 10

[0196] It can be seen that compared with Comparative Example 1, in Examples 1 to 15, the coarse fiber layer and the fine fiber layer are introduced with the profiled cross-section fibers, and the perimeter coefficient X of the profiled cross-section fibers is controlled. L Satisfy 1<X L ≤5, which can effectively improve the strength of the non-woven fabric and improve the wettability of the non-woven fabric to the electrolyte, so that the non-woven fabric has better wettability to the electrolyte and faster wetting speed.

[0197] Among them, compared with Example 5 (the surface of the special-shaped cross-section fiber has no grooves), the special-shaped cross-section fiber in Example 1 has grooves, which can further improve the strength and electrolyte wettability of the non-woven fabric.

[0198] Among them, compared with Example 10 (w / D < 15%, h / D > 75%), the modified cross-section fibers in Example 1 satisfy w / D ≥ 15%, h / D ≤ 75%, which can further improve the strength of the nonwoven fabric.

[0199] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A non-woven fabric, characterized in that, It includes at least one fine fiber layer and at least one coarse fiber layer arranged in a stacked manner. Both the fine fiber layer and the coarse fiber layer respectively include main fibers, and the main fibers include circular cross-section fibers and profiled cross-section fibers. The perimeter coefficient of the cross-section of at least part of the profiled cross-section fibers is X L , 1 < X L ≤ 5; The linear density of the main fibers of the fine fiber layer is less than the linear density of the main fibers of the coarse fiber layer.

2. The non-woven fabric according to claim 1, characterized in that, meeting at least one of the following conditions: a. The difference between the linear density of the main fibers in the coarse fiber layer and the linear density of the main fibers in the fine fiber layer is 0.1 to 0.7 dtex; b. The linear density of the main fibers in the fine fiber layer is less than or equal to 0.4 dtex; c. The linear density of the main fibers in the coarse fiber layer is 0.4 to 1.0 dtex.

3. The non-woven fabric according to claim 1, characterized in that, meeting at least one of the following conditions: a. The non-woven fabric includes at least two layers of the fine fiber layer, and there is the coarse fiber layer between every two adjacent layers of the fine fiber layer; b. The non-woven fabric includes at least two layers of the coarse fiber layer, and there is the fine fiber layer between every two adjacent layers of the coarse fiber layer.

4. The non-woven fabric according to claim 1, characterized in that, the mass ratio of the fine fiber layer to the non-woven fabric is 10% to 30%.

5. The non-woven fabric according to claim 1, characterized in that, the surface of the profiled cross-section fiber is provided with grooves.

6. The non-woven fabric according to claim 5, characterized in that, meeting at least one of the following conditions: a. The width of the widest part of the groove is not less than 15% of the diameter of the circumscribed circle of the cross-section of the profiled cross-section fiber; b. The depth of the deepest part of the groove is not higher than 75% of the diameter of the circumscribed circle of the cross-section of the profiled cross-section fiber.

7. The non-woven fabric according to claim 5, characterized in that, meeting at least one of the following conditions: a. The number of the grooves on the surface of the profiled cross-section fiber is one or more. When there are multiple grooves, the multiple grooves are distributed along the circumferential direction of the profiled cross-section fiber; b. The groove extends along the axial direction of the profiled cross-section fiber and penetrates the profiled cross-section fiber.

8. The non-woven fabric according to any one of claims 5-7, characterized in that, the number of the grooves is less than or equal to 16.

9. The non-woven fabric according to any one of claims 1-7, characterized in that, meeting at least one of the following conditions: a. In the fine fiber layer, the mass ratio of the profiled cross-section fiber to the main fiber is 10% to 90%; b. In the fine fiber layer, the mass percentage of the main fiber is 60% to 80%; c. In the fine fiber layer, the length of the main fiber is 1 mm to 3 mm; d. In the coarse fiber layer, the mass ratio of the profiled cross-section fiber to the main fiber is 10% to 60%; e. In the coarse fiber layer, the mass percentage of the main fiber is 60% to 80%; f. In the coarse fiber layer, the length of the main fiber is 1 mm to 6 mm.

10. The non-woven fabric according to any one of claims 1-7, characterized in that, meeting at least one of the following conditions: a. The areal density of the coarse fiber layer is greater than that of the fine fiber layer. Preferably, the difference between the areal density of the coarse fiber layer and the areal density of the fine fiber layer is not greater than 20 g / m 2 ; b. The areal density of the coarse fiber layer is 4 g / m 2 ~24 g / m 2 ; c. The areal density of the fine fiber layer is greater than 0 and not greater than 8 g / m 2 .

11. The non-woven fabric according to any one of claims 1-7, characterized in that, The coarse fiber layer and the fine fiber layer each include binder fibers, and the softening point of the main fibers is greater than the softening point of the binder fibers.

12. The non-woven fabric according to claim 11, wherein, at least one of the following conditions is satisfied: a. The difference between the softening point of the main fibers and the softening point of the binder fibers is greater than or equal to 20°C; b. The softening point of the binder fibers is greater than or equal to 120°C.

13. The non-woven fabric according to claim 11, wherein, at least one of the following conditions is satisfied: a. In the fine fiber layer, the linear density of the binder fibers is less than or equal to 0.4 dtex; b. In the fine fiber layer, the length of the binder fibers is 1 mm to 3 mm; c. In the fine fiber layer, the mass percentage content of the binder fibers is 20% to 40%; d. In the coarse fiber layer, the linear density of the binder fibers is 0.4 dtex to 1.8 dtex; e. In the coarse fiber layer, the length of the binder fibers is 1 mm to 6 mm; f. In the coarse fiber layer, the mass percentage content of the binder fibers is 20% to 40%.

14. The non-woven fabric according to claim 11, wherein, the binder fibers include one or more of unstretched polyester fibers, polyvinylidene fluoride fibers, polyamide fibers, copolyamide fibers, polyolefin fibers, copolyester fibers, and copolyamide fibers; Optionally, the unstretched polyester fibers include polyethylene terephthalate and / or polybutylene terephthalate; Optionally, the polyolefin fibers include one or more of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyethylene / polypropylene core-sheath fibers, polyethylene / polyethylene terephthalate core-sheath fibers, and polyethylene / polytetramethylene terephthalate core-sheath; Optionally, the copolyester fibers include at least one of CoPET or CoPBT; Optionally, the copolyamide fibers include one or more of PA6 / 6, PA6 / 66, PA6 / 66 / 12, PA6 / 66 / 69, PA6 / 66 / 610, PA6 / 66 / 612, PA6 / 66 / 1010, PA6 / 612 / 12, PA6 / 610 / 12, PA6 / 66 / 69 / 12, and PA6 / 66 / 11 / 12.

15. The non-woven fabric according to any one of claims 1-7, wherein, at least one of the circular cross-section fibers and the profiled cross-section fibers includes one or more of polyester fibers, polyolefin fibers, polyamide fibers, polyimide fibers, polytetrafluoroethylene fibers, polyphenylene sulfide fibers, polyether ether ketone fibers, polyacrylonitrile fibers, polycarbonate fibers, and aramid fibers; Optionally, the polyester fibers include one or more of polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and polyisophthalic acid resin. Optionally, the polyolefin fiber includes one or more of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyethylene / polypropylene core-sheath fiber, polyethylene / polyethylene terephthalate core-sheath fiber, and polyethylene / polybutylene terephthalate core-sheath fiber; Optionally, the polyamide fiber includes PA66.

16. The non-woven fabric according to any one of claims 1-7, characterized in that, meeting at least one of the following conditions: a. The thickness of the non-woven fabric is 5 μm to 30 μm; b. The areal density of the non-woven fabric is 4 g / m 2 ~25 g / m 2 ; c. The density of the non-woven fabric is 0.5 g / cm 3 to 0.9 g / cm 3 .

17. A separator, characterized in that, comprising the non-woven fabric according to any one of claims 1-16.

18. The separator according to claim 17, characterized in that, further comprising a coating, wherein the coating is provided on at least one region selected from the surface of the non-woven fabric and at least a part of the pores present in the non-woven fabric.

19. The separator according to claim 18, characterized in that, meeting at least one of the following conditions: a. At least one side surface layer of the non-woven fabric is the fine fiber layer, and the coating is at least located on the fine fiber layer; b. At least one side surface layer of the non-woven fabric is the coarse fiber layer, and the coating is at least located on the coarse fiber layer.

20. A battery, characterized in that, comprising the separator according to any one of claims 17-19.

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