Non-woven fabric, diaphragm and battery

Abstract

The invention provides a non-woven fabric, a diaphragm and a battery, the non-woven fabric comprises a trunk fiber, the trunk fiber comprises a circular cross-section fiber and a special-shaped cross-section fiber; 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 strength of the non-woven fabric can be improved, and meanwhile, the thin thickness of the non-woven fabric is kept, so that the performances of safety, cycle life, energy density and the like of a battery are considered.

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 such as batteries. For example, they can be used to form non-woven separators for use in batteries. However, in related technologies, it is often difficult to balance the strength and thickness of non-woven fabrics. Thinner non-woven fabrics have lower strength, which is detrimental to battery safety and cycle life. Increasing the thickness of the non-woven fabric can affect battery performance, such as energy density.

[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 while maintaining its relatively thin thickness, thereby taking into account the safety, cycle life and energy density of the battery.

[0005] In one aspect of the present invention, a nonwoven fabric is provided, comprising a main fiber, wherein the main fiber comprises a circular cross-section fiber and a special-shaped cross-section fiber; the perimeter coefficient of the cross section of at least part of the special-shaped cross-section fiber is X L , 1<X L ≤5.

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

[0007] In another aspect of the present invention, a battery is provided, comprising a positive electrode sheet, a negative electrode sheet, and the aforementioned separator, wherein the separator is located between the positive electrode sheet and the negative electrode sheet.

[0008] In the present invention, the main fibers of the nonwoven fabric 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. By introducing these specific forms of backbone fibers, the fibers in the non-woven fabric are fully bonded to form a strong network structure, which significantly improves the strength of the non-woven fabric while maintaining a thin thickness. Specifically, the longitudinal tensile strength of the non-woven fabric can be as high as 469kgf / cm 2 Above, even up to 540kgf / cm 2 Above, the transverse tensile strength can be as high as 300kgf / cm 2 Above, even up to 330kgf / cm 2The thickness of the non-woven fabric is no more than 25 μm. The present invention thus provides a thin, high-strength non-woven fabric that can be used as a separator in electrochemical energy storage devices such as lithium-ion batteries, thereby improving the safety, cycle life, and energy density of electrochemical energy storage devices such as lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG1 is a schematic diagram of a cross-sectional shape (cross-shaped) of a special-shaped cross-sectional fiber in one embodiment of the present invention;

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

[0011] FIG3 is a schematic diagram of the cross-sectional shape (seven-eighths circle) of a special-shaped cross-section fiber in another embodiment of the present invention (A in FIG3 shows the central angle, and B in FIG3 shows the deepest depth and the widest width);

[0012] FIG4 is a schematic diagram of the cross-sectional shape (octagonal star shape) of a special-shaped cross-section fiber in another embodiment of the present invention;

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

[0014] FIG6 is a schematic diagram of the cross-sectional shape (decagonal star) of a special-shaped cross-sectional fiber in another embodiment of the present invention;

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

[0016] FIG8 is a schematic diagram of the cross-sectional shape (twelve-pointed star) of a special-shaped cross-sectional fiber in another embodiment of the present invention;

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

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

[0019] FIG11 is a schematic diagram of the cross-sectional shape (quadrangular star) of a special-shaped cross-sectional fiber in another embodiment of the present invention;

[0020] FIG12 is a schematic diagram of the cross-sectional shape (T-shaped) of a special-shaped cross-sectional fiber in another embodiment of the present invention;

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

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

[0023] FIG15 is a schematic diagram of the cross-sectional shape (W-shaped) of a special-shaped cross-sectional fiber in another embodiment of the present invention;

[0024] FIG16 is a schematic diagram of the cross-sectional shape (N-shaped) of a special-shaped cross-sectional fiber in another embodiment of the present invention;

[0025] FIG17 is a schematic diagram of the cross-sectional shape (U-shaped) of a special-shaped cross-sectional fiber in another embodiment of the present invention;

[0026] FIG18 is a schematic diagram of the cross-sectional shape (open circular shape) of a special-shaped cross-section fiber in another embodiment of the present invention;

[0027] FIG19 is a schematic diagram of the cross-sectional shape (pentagon) of a special-shaped cross-sectional fiber in another embodiment of the present invention;

[0028] FIG20 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;

[0029] FIG21 is a differential scanning calorimetry curve of the fiber.

[0030] 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

[0031] 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.

[0032] With the development of new energy vehicles, 3C and other technological fields, lithium-ion batteries have gradually been widely used. At the same time, higher and higher requirements have been placed on the energy density and safety of lithium-ion batteries. For example, the theoretical energy density of existing power battery systems has gradually reached its technical upper limit, and further breakthroughs are difficult.

[0033] Specifically, liquid batteries require a diaphragm to separate the positive and negative electrodes, and use electrolyte for ion conduction. Their safety has always been an aspect that needs to be improved urgently. Among them, conventional diaphragms such as polyolefin diaphragms in liquid batteries have poor thermal stability and other performance, which has caused many constraints on the safety of liquid batteries.

[0034] Compared to liquid batteries, semi-solid-state and solid-state batteries offer advantages in safety, energy density, and cycle life, and are gradually gaining widespread attention. The separators in these batteries replace the electrolyte, fulfilling the role of electrolyte and placing high demands on the separator's strength and other properties. Semi-solid-state batteries still require electrolyte for ion conduction and separator for insulation, placing higher demands on the separator's strength, heat resistance, and other properties.

[0035] 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.

[0036] However, in related technologies, it is usually difficult to strike a balance between the strength and thickness of non-woven fabrics. If the thickness of the non-woven fabric is reduced, its strength will be weakened, which is not conducive to the safety and cycle life of the battery. If the thickness of the non-woven fabric is increased, it will affect the energy density and other performance of the battery.

[0037] In view of this, an embodiment of the present invention provides a non-woven fabric, including a main fiber, the main fiber including a circular cross-section fiber and a special-shaped cross-section fiber; 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.

[0038] Specifically, the nonwoven fabric may contain one type of shaped cross-section fibers (i.e., the cross-section 1 of these shaped cross-section fibers has the same shape), or 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.

[0039] For example, the perimeter coefficient of the cross section 1 of the at least partially shaped cross-section fiber may be 1.5, 2, 3, 4, 5 or a range consisting of any two thereof.

[0040] 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 =Equal to the ratio of the perimeter C0 of the cross section 1 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 / T 50002-2013 (test method for chemical fiber profile) of the People's Republic of China.

[0041] 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).

[0042] In the above non-woven fabric, the main fibers serve as the skeleton of the non-woven fabric. By simultaneously introducing circular main fibers (i.e., the above circular cross-section fibers) and special-shaped main fibers (i.e., the above special-shaped cross-section fibers) into the non-woven fabric, and controlling the perimeter coefficient X of the cross section 1 of the special-shaped main fibers, the perimeter coefficient X of the cross section 1 of the special-shaped main fibers is obtained. L Satisfy 1<X L ≤5, which can significantly improve the strength of non-woven fabrics while maintaining a thin thickness of non-woven fabrics. Specifically, the longitudinal tensile strength of non-woven fabrics can be as high as 469kgf / cm 2 Above, even up to 540kgf / cm 2 Above, the transverse tensile strength can be as high as 300kgf / cm 2 Above, even up to 330kgf / cm 2 The thickness of the non-woven fabric is no more than 25 μm. Thus, the embodiments of the present invention provide a thin, high-strength non-woven fabric that can be used as a separator in electrochemical energy storage devices such as lithium-ion batteries, thereby improving the safety, cycle life, and energy density of electrochemical energy storage devices such as lithium-ion batteries.

[0043] 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 the fibers with special cross-sections, making it easy for the main fibers to clump together and difficult to fully disperse evenly, which is not conducive to obtaining a non-woven fabric with high performance uniformity.

[0044] Generally, non-woven fabrics also include bonding fibers. The softening point of the main fibers is greater than that of the bonding fibers. The bonding fibers are mainly used to bond the main fibers and other components in the non-woven fabrics to improve the structural strength of the non-woven fabrics.

[0045] 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.

[0046] Generally speaking, under the condition of 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 non-woven fabric, the surface area of ​​the irregular cross-sectional fiber is significantly higher than that of the circular cross-sectional fiber. L Satisfy 1<X L The special-shaped cross-section fibers with a diameter of ≤5 can make use of 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, so that the melted part of the bonding fibers can be more fully and quickly infiltrated, which greatly increases the bonding area between the fibers and significantly improves the structural strength of the non-woven fabric.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] Generally, there are multiple fibers with different cross-sections in a nonwoven fabric, and the number of grooves 10 on these fibers with different cross-sections can be the same or different. As mentioned above, the nonwoven fabric contains at least one type of fiber with different cross-sections, that is, it can contain one type of fiber with different cross-sections or multiple types of fibers with different cross-sections. When multiple types of fibers with different cross-sections are present, the number of grooves 10 on any two of the fibers with different cross-sections can be the same or different.

[0052] 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.

[0053] 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.

[0054] 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 of the non-woven fabric.

[0055] In some embodiments, in the special-shaped cross-section fiber, the deepest depth h of the groove 10 may not be higher than 75% of the diameter D of the circumscribed circle 100 of the cross-section 1 of the special-shaped cross-section fiber (that is, h / D≤75%), and h / D may specifically satisfy 0<h / D≤75%. For example, h / D is 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or a range consisting of any two of them, which can further improve the structural strength of the non-woven fabric.

[0056] 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.

[0057] For example, referring to Figures 1 to 19, 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.

[0058] For example, referring to FIG. 20 , 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.

[0059] In addition, continuing to refer to Figures 1 to 20, 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 10 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 opening of the groove 10 that enclose the two side walls of the groove 10 is the above-mentioned connecting line.

[0060] It can be understood that the above-mentioned straight lines, connecting lines and 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.

[0061] Specifically, the shape of the cross section 1 of the above-mentioned special-shaped cross-section fiber may include heart shape, dumbbell shape, crescent shape (as shown in Figure 10), crescent shape (as shown in Figure 14), incomplete circular ring shape, incomplete circle, multi-leaf clover shape, polygonal shape, character shape or plum blossom shape, but is not limited to these, and may also be other regular or irregular shapes.

[0062] 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, as shown in Figure 2), or a two-thirds circular ring (that is, the central angle corresponding to the outer circle arc of the incomplete circular ring is 2 / 3 of the central angle corresponding to the outer circle arc of its complete concentric circular ring), or an incomplete circular ring as shown in Figure 20.

[0063] Among them, the central angle α of the non-complete circle (including fan-shaped, arc-shaped and open circle) is less than 360°. For example, the non-complete circle includes a seven-eighths circle (that is, its central angle α accounts for seven-eighths of 360°, as shown in Figure 3 (A in Figure 3 shows the central angle, and B in Figure 3 shows the deepest depth h and the widest width w)), a three-quarters circle (that is, its central angle α accounts for three-quarters of 360°) or a two-thirds circle (that is, its central angle α accounts for two-thirds of 360°), or a circle as shown in Figure 18.

[0064] Illustratively, the multi-leaf clover shape includes a three-leaf clover shape or a four-leaf clover shape.

[0065] Exemplarily, the polygon includes a pentagon (as shown in FIG19 ), and may also include a polygon, the polygon including a triangular star, a quadrangular star (as shown in FIG11 ), a pentagram, a hexagonal star, an octagonal star (as shown in FIG4 ), a decagram (as shown in FIG6 ), a dodecagram (as shown in FIG8 ), or a hexadecagram (as shown in FIG9 ).

[0066] Exemplarily, the character shapes include a cross shape (as shown in Figures 1 and 13), a double cross shape, an I-shape, a M-shape (as shown in Figure 7), 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 (as shown in Figure 16), an S-shape (as shown in Figure 5), a T-shape (as shown in Figure 12), a U-shape (as shown in Figure 17), a V-shape, a W-shape (as shown in Figure 15), an X-shape, a Y-shape or a Z-shape.

[0067] 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.

[0068] In some embodiments, the ratio of the mass of the special-shaped cross-section fibers to the mass of the trunk fibers (the mass percentage of the special-shaped cross-section fibers in the trunk fibers) can be 5% to 60%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60% or a range consisting of any two of them, which is beneficial to improving the structural strength of the non-woven fabric.

[0069] In addition, the mass ratio of circular cross-section fibers to trunk fibers (the mass percentage of circular cross-section fibers in the trunk fibers) can be 40% to 95%, for example, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or a range consisting of any two of them, which is beneficial to improving the structural strength of the non-woven fabric.

[0070] In some embodiments, the ratio of the mass of the backbone fiber to the mass of the non-woven fabric (i.e., the mass percentage of the backbone fiber in the non-woven fabric) can be 60% to 85%, for example, 60%, 63%, 65%, 68%, 70%, 73%, 75%, 78%, 80%, 83%, 85% or a range consisting of any two of them, which is beneficial to improving the structural strength of the non-woven fabric.

[0071] The linear density of a fiber indicates its thickness. Under the same conditions, overly thick fibers will make the non-woven fabric too heavy, which is detrimental to its performance when used in battery separators and electrolyte membranes. Taking the separator as an example, if the non-woven fabric is too thick (the linear density is too high) or too heavy, it will increase the ion transmission resistance of the separator and change the diffusion coefficient, thereby causing uneven transmission of ions (such as lithium ions) and increasing the unevenness of ions reaching the electrode interface. The unevenness of ions entering and exiting the electrode through the separator will cause incomplete lithium insertion and removal, as well as local overcharge or over-discharge, thereby affecting the safety and life of the battery.

[0072] Therefore, in some preferred embodiments, the linear density of the above-mentioned trunk fibers can be less than or equal to 0.4dtex, that is, the linear density of the above-mentioned circular cross-section fibers can be less than or equal to 0.4dtex, and the linear density of the special-shaped cross-section fibers can be less than or equal to 0.4dtex. This can avoid the non-woven fabric being too thick, and makes it easier to use the non-woven fabric for battery separators and electrolyte membranes, further improving the safety and cycle life of the battery and other performance.

[0073] Furthermore, the linear density of the above-mentioned trunk fibers (circular cross-section fibers or special-shaped cross-section fibers) can be 0.05dtex to 0.4dtex, for example, 0.05dtex, 0.06dtex, 0.08dtex, 0.1dtex, 0.15dtex, 0.2dtex, 0.25dtex, 0.3dtex, 0.35dtex, 0.4dtex or a range consisting of any two of them.

[0074] The linear density of the circular cross-section fibers and the shaped cross-section fibers can be the same or different, i.e., the linear density of the circular cross-section fibers can be greater than, equal to, or less than the linear density of the shaped cross-section fibers. Furthermore, in some preferred embodiments, the linear density of the binder fibers is less than or equal to 0.8 dtex, which facilitates the use of the nonwoven fabric in battery separators and electrolyte membranes, improving battery safety and cycle life.

[0075] Furthermore, the linear density of the binder fiber may be in the range of 0.2 dtex to 0.8 dtex, for example, 0.2 dtex, 0.3 dtex, 0.4 dtex, 0.5 dtex, 0.6 dtex, 0.7 dtex, 0.8 dtex or any two thereof.

[0076] Among them, the linear density of the bonding fiber and the trunk fiber (circular cross-section fiber or special-shaped cross-section fiber) can be the same or different, that is, the linear density of the bonding fiber can be greater than, equal to or less than the linear density of the circular cross-section fiber, and the linear density of the bonding fiber can be greater than, equal to or less than the linear density of the special-shaped cross-section fiber.

[0077] In addition, the length of the main fiber can be 1mm to 3mm, that is, the length of the circular cross-section fiber can be 1mm to 3mm, and the length of the special-shaped cross-section fiber can be 1mm to 3mm, which is conducive to further improving the structural strength and other properties of the non-woven fabric.

[0078] For example, the length of the main fibers (circular cross-section fibers and 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.

[0079] The lengths of the circular cross-section fiber and the irregular cross-section fiber may be the same or different, that is, the length of the circular cross-section fiber may be greater than, equal to, or less than the length of the irregular cross-section fiber.

[0080] Furthermore, the length of the binder 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 combination thereof.

[0081] Among them, the length of the bonding fiber can be the same as or different from the length of the main fiber (special-section fiber, circular-section fiber), that is, the length of the bonding fiber can be greater than, equal to or less than the length of the circular-section fiber, and the length of the bonding fiber can be greater than, equal to or less than the length of the special-section fiber.

[0082] The linear density of the trunk fibers and the linear density of the bonding fibers are both average linear densities, which can be measured by conventional methods in the art, for example, by the test method for linear density of chemical staple fibers specified in GB / T 14335-2008.

[0083] The length of the above-mentioned main fibers and the length of the bonding fibers refer to average lengths, which can be measured by conventional methods in the art, for example, by the test method for length of chemical staple fibers in GB / T 14336-2008.

[0084] In addition, 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 morphological structure 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. That is, the difference between the softening points of circular cross-section fibers and the binder fibers can be greater than or equal to 20°C, and the difference between the softening points of special-shaped cross-section fibers and the binder fibers can be greater than or equal to 20°C.

[0085] The softening point of the circular cross-section fiber and the softening point of the profiled cross-section fiber may be the same or different, that is, the softening point of the circular cross-section fiber may be greater than, equal to, or less than the softening point of the profiled cross-section fiber.

[0086] In some embodiments, 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 binder fiber can be specifically 20-280°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°C, 130°C, 135°C, 140°C, 145°C, 150°C, 160°C, 165°C, 170°C, 180°C, 190°C, 195°C, 200°C, 205°C, 210°C, 220°C, 230°C, 240°C, 250°C, 252°C, 255°C, 260°C, 265°C, 270°C, 275°C, 280°C or a range consisting of any two of them.

[0087] In some embodiments, the softening point of the trunk fiber (circular cross-section fiber or special-shaped cross-section fiber) can be 240°C to 400°C, for example, 240°C, 245°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.

[0088] Specifically, the softening point of the binder fiber may be greater than or equal to 120° C. In some embodiments, the softening point of the binder fiber may be in the range of 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 any two thereof.

[0089] 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 21), 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).

[0090] In some embodiments, the binder fiber may include one or more of undrawn polyester fiber, polyvinylidene fluoride fiber (PVDF), polyamide fiber, polyolefin fiber, copolyester fiber, and copolyamide fiber.

[0091] Alternatively, the undrawn polyester fiber may include at least one of polyethylene terephthalate (PET) or polybutylene terephthalate.

[0092] 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, and polyethylene / polybutylene terephthalate sheath-core fiber.

[0093] 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.

[0094] 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.

[0095] For example, the bonding fiber may include a PE / PP bicomponent fiber, which may specifically be a PE / PP bicomponent sheath-core fiber (i.e., the above-mentioned polyethylene / polypropylene sheath-core fiber). The PE / PP bicomponent sheath-core fiber includes a core layer and a sheath layer present on the surface of the core layer. The sheath layer may specifically be wrapped around the circumference of the core layer. The core layer includes PE, and the sheath layer includes PP.

[0096] Alternatively, the copolyester fiber may include at least one of a copolymer of ethylene terephthalate fiber (CoPET) or a copolymer of butylene terephthalate fiber (CoPBT).

[0097] Optionally, the copolyamide fiber is formed by copolymerizing monomers of at least two polyamides, and the at least two polyamides include, for example, at least 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 can be a copolymer of monomers of at least two of these polyamides.

[0098] Specifically, the copolyamide fiber may include at least one of binary copolyamide, ternary copolyamide, or tetrapolyamide.

[0099] 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 ternary copolyamide formed by copolymerizing monomers of polyamide 6, polyamide 66, and polyamide 69). PA6 / 66 / 69 (a ternary copolyamide 6 / 66 / 610 formed by copolymerization of a monomer of polyamide 6, a monomer of polyamide 66 and a monomer of polyamide 610), PA6 / 66 / 612 (a ternary copolyamide 6 / 66 / 612 formed by copolymerization of a monomer of polyamide 6, a monomer of polyamide 66 and a monomer of polyamide 612), PA6 / 66 / 1010 (a ternary copolyamide 6 / 66 / 1010 formed by copolymerization of a monomer of polyamide 6, a monomer of polyamide 66 and a monomer of polyamide 1010), One or more of PA6 / 612 / 12 (ternary copolymerized polyamide 6 / 612 / 12 formed by copolymerizing monomers of polyamide 6, polyamide 612 and polyamide 12), PA6 / 610 / 12 (ternary copolymerized polyamide 6 / 610 / 12 formed by copolymerizing monomers of polyamide 6, polyamide 610 and polyamide 12), PA6 / 66 / 69 / 12 (quaternary copolymerized polyamide 6 / 66 / 69 / 12 formed by copolymerizing monomers of polyamide 6, polyamide 66, polyamide 69 and polyamide 12), and PA6 / 66 / 11 / 12 (quaternary copolymerized polyamide 6 / 66 / 11 / 12 formed by copolymerizing monomers of polyamide 6, polyamide 66, polyamide 11 and polyamide 12).

[0100] In some embodiments, the main fibers (i.e., circular cross-section fibers and 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; polyester fibers include one or more of polyethylene terephthalate (PET), polybutylene terephthalate, polytrimethylene terephthalate, and polyisophthalic acid resins; polyolefin fibers include one or more of polyethylene, polypropylene (PP), polyvinyl chloride, and polystyrene; and polyamide fibers include PA66.

[0101] The material of the circular cross-section fiber and the material of the irregular cross-section fiber can be the same or different.

[0102] In addition, the thickness of the non-woven fabric can be less than or equal to 25 μm, which can maintain a relatively thin thickness while also having strong structural strength. In some embodiments, the thickness of the non-woven fabric can be specifically 5 μm to 25 μm, for example, 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 18 μm, 20 μm, 23 μm, 25 μm, or any two thereof, which is more conducive to its use as a battery separator or electrolyte membrane, while taking into account the improvement of battery performance such as energy density and safety.

[0103] In addition, the surface density of the non-woven fabric can be 4g / m 2 ~20g / 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 or a range consisting of any two of them.

[0104] 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 / cm 3 or a range consisting of any two of them.

[0105] The above-mentioned non-woven fabric can be produced by conventional methods in the art, which are not particularly limited. For example, the raw materials for forming the non-woven fabric (such as the above-mentioned main fibers and binder fibers, etc.) are used to make 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 roll / soft roll or a steel roll / steel roll combination, and the hot calendering treatment temperature is, for example, 100°C to 300°C. After the hot calendering treatment, the non-woven fabric is produced.

[0106] The separator provided by the embodiments of the present invention includes the aforementioned non-woven fabric, i.e., the separator is a non-woven fabric separator. As previously mentioned, the non-woven fabric can have both a relatively thin thickness and a high structural strength, and can be used in separators to simultaneously reduce separator thickness and improve separator strength, thereby simultaneously improving the safety, cycle life, and energy density of electrochemical energy storage devices such as lithium-ion batteries that employ the separator.

[0107] Specifically, electrochemical devices such as lithium-ion batteries include a positive electrode and a negative electrode, with the separator positioned between them to separate them. This separator can be used in liquid, semi-solid, or solid-state batteries. When used in these batteries, it also functions as an electrolyte, acting as an electrolyte membrane, replacing the electrolyte solution. However, in semi-solid batteries, electrolyte solution is generally still required.

[0108] Generally speaking, the above-mentioned diaphragm may also include a component compounded with a non-woven fabric. The non-woven fabric serves as the skeleton of the diaphragm and is used 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. In addition, the component can also form a coating on the surface of the non-woven fabric.

[0109] 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 special-shaped cross-section fibers is irregular in shape. By introducing special-shaped cross-section fibers into non-woven fabrics, the number and size of capillary pores inside the non-woven fabrics can be controlled. At the same time, the specific surface area and capillary effect of fibers and fiber webs in non-woven fabrics are significantly increased, which is beneficial to enhance the absorption, transfer and retention of components composited with non-woven fabrics by non-woven fabrics, and optimize the performance of non-woven fabric membranes.

[0110] Specifically, when the separator is applied to a liquid battery, the component compounded with the non-woven fabric in the separator may include inorganic particles, polymers or a combination thereof.

[0111] Specifically, when the above-mentioned diaphragm is applied to a semi-solid battery or a solid-state battery, the component compounded with the non-woven fabric in the diaphragm (electrolyte membrane) may be a solid electrolyte, which may specifically include one or more of a polymer electrolyte, an oxide electrolyte, a sulfide electrolyte, etc., but is not limited thereto.

[0112] In specific implementation, the components for compounding with the non-woven fabric can be prepared into a slurry, which is then coated on the non-woven fabric and then dried to form a coating.

[0113] When the above-mentioned separator is an electrolyte membrane (for example, an electrolyte membrane used in solid-state batteries or semi-solid-state batteries), by using the above-mentioned cross-sectional perimeter coefficient X L Satisfy 1<X LThe non-woven fabric with shaped cross-section fibers of ≤5 can also significantly increase the contact area between the non-woven fabric and the solid electrolyte, and enhance the adsorption and wrapping ability of the non-woven fabric for the solid electrolyte, which is conducive to more sufficient and effective filling of the solid electrolyte in the non-woven fabric, improving the filling density and loading of the solid electrolyte in the non-woven fabric, and improving the interface contact problem of the solid electrolyte. At the same time, it can achieve a strong bond between the solid electrolyte and the non-woven fabric through the anchoring effect, which is conducive to reducing the solid / solid interface impedance between the solid electrolyte and the non-woven fabric fibers. Therefore, the electrolyte membrane of the embodiment of the present invention can take into account the improvement of the safety, cycle life, energy density, and rate performance of electrochemical energy storage devices such as lithium-ion batteries.

[0114] Specifically, using the above-mentioned non-woven fabric, during the preparation of the electrolyte membrane, the solid electrolyte slurry enters 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 solid electrolyte slurry will also enter the fine grooves 10 on the surface of the irregular cross-section fibers. The strong wicking and capillary action help the solid electrolyte 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 solid electrolyte and enhancing the adsorption and holding capacity of the non-woven fabric for the solid electrolyte, which is beneficial to the Improve the filling density and loading capacity of solid electrolyte in non-woven fabric, more fully and effectively fill, and improve the interface contact problem of solid electrolyte; at the same time, realize strong bonding between solid electrolyte and non-woven fabric through anchoring effect, and solid electrolyte slurry penetrates into the fiber surface, gaps, pores or concave-convex structures inside the non-woven fabric. After drying and curing, meshing force is generated at the contact section, thereby achieving high bonding strength between solid electrolyte and non-woven fabric, which is beneficial to reduce the solid / solid interface impedance between solid electrolyte and non-woven fabric fibers, thereby effectively improving the battery's rate performance and other performance.

[0115] In addition, in the embodiment of the present invention, when the above-mentioned diaphragm is applied to a liquid battery (conducting ions (such as lithium ions) through an electrolyte) or a semi-solid battery injected with an electrolyte, the high specific surface area of ​​the fibers inside the non-woven fabric can also increase the liquid absorption rate of the non-woven fabric diaphragm to the electrolyte, especially when the surface of the special-shaped cross-section fiber has grooves 10, the capillary force generated by the fine grooves 10 on the fiber surface allows the electrolyte to quickly infiltrate the surface and interior of the non-woven fabric through wicking, thereby increasing the liquid absorption rate and retention of the non-woven fabric diaphragm to the electrolyte. The liquid volume is significantly increased, and a stable electrolyte adsorption layer can be formed on the surface of the non-woven fabric, which reduces the penetration resistance of the electrolyte in the battery and improves the interface properties of the diaphragm. At the same time, the non-woven fabric diaphragm is enhanced in its ability to retain the electrolyte entering the interior of the non-woven fabric due to the pores with high specific surface area and the capillary force of the fiber micro-grooves 10, which is beneficial to the rapid transfer of ions (such as lithium ions) and can effectively prevent the diaphragm from leaking during use and the resulting electrolyte depletion.

[0116] In the related art, in order to form a continuous coating layer, it is usually necessary to apply more slurry, which makes the non-woven fabric separator have defects such as a large thickness. In the embodiment of the present invention, by using the above-mentioned cross-sectional perimeter coefficient X L Satisfy 1<X L The non-woven fabric with shaped cross-section fibers of ≤5 greatly increases the specific surface area of ​​the non-woven fabric surface and strengthens the adsorption and wrapping ability of the slurry. Therefore, a small amount of coating on the outer surface of the non-woven fabric can form a continuous coating layer. Compared with the existing non-woven fabric separators, in the embodiment of the present invention, the slurry is not easy to transition to the inside of the non-woven fabric, and it is even more difficult to penetrate from the side (front) of the non-woven fabric coated with the slurry to the other side (back) of the non-woven fabric. The amount of slurry used and the thickness of the coating layer formed can be significantly reduced, thereby reducing the thickness of the separator. At the same time, the irregular cross-section of the shaped cross-section fibers in the non-woven fabric enhances the anchoring effect of the non-woven fabric and the coating layer, achieving a strong bond between the coating layer and the non-woven fabric, thereby obtaining a non-woven fabric separator with excellent performance.

[0117] In addition, the diaphragm of the embodiment of the present invention can also be applied to solid-state batteries prepared by the technical route of in-situ polymerization of polymer electrolytes. During the preparation of the battery, it is necessary to use an injection process to inject the electrolyte solution (electrolyte) into the battery cell for in-situ polymerization reaction (the electrolyte contains monomers for polymerizing to form a gel polymer electrolyte, that is, during the in-situ polymerization reaction, the monomers are in-situ polymerized into a gel polymer electrolyte). In the embodiment of the present invention, by introducing the cross-sectional perimeter coefficient X into the non-woven fabric, the cross-sectional perimeter coefficient X is increased. L Satisfy 1<X L≤5, especially when the surface of the special-shaped cross-section fiber has grooves 10, the non-woven fabric can also absorb the electrolyte quickly and have a good flow conduction effect, thereby promoting the uniform and rapid transmission and diffusion of the electrolyte in the battery system, as well as the uniformity of the electrolyte dispersion, and improving the efficiency of the in-situ polymerization reaction.

[0118] The battery provided by the embodiment of the present invention includes a positive electrode sheet, a negative electrode sheet and the above-mentioned separator, and the separator is located between the positive electrode sheet and the negative electrode sheet.

[0119] As previously mentioned, the batteries of the embodiments of the present invention may be liquid batteries, semi-solid batteries, or solid-state batteries. These batteries may be conventional in the art and are not particularly limited thereto. By employing the aforementioned separator, battery performance such as safety, cycle life, and energy density can be improved.

[0120] The present invention is further described below through specific embodiments. In the following embodiments, the shape of the cross section 1 of the special-shaped cross-section fiber of Example 1 is shown in FIG1 , the shape of the cross section 1 of the special-shaped cross-section fiber of Example 2 is shown in FIG9 , the shape of the cross section 1 of the special-shaped cross-section fiber of Example 3 is shown in FIG3 , the shape of the cross section 1 of the special-shaped cross-section fiber of Example 4 is shown in FIG4 , the shape of the cross section 1 of the special-shaped cross-section fiber of Example 5 is shown in FIG5 , the shape of the cross section 1 of the special-shaped cross-section fiber of Example 6 is shown in FIG6 , the shape of the cross section 1 of the special-shaped cross-section fiber of Example 7 is shown in FIG7 , the shape of the cross section 1 of the special-shaped cross-section fiber of Example 8 is shown in FIG8 , the shape of the cross section 1 of the special-shaped cross-section fiber of Example 9 is shown in FIG9 , the shape of the cross section 1 of the special-shaped cross-section fiber of Example 10 is shown in FIG10 , and the shape of the cross section 1 of the special-shaped cross-section fiber of Example 11 is shown in FIG11 . The shape of the cross-section 1 of the special-shaped cross-section fiber of Example 12 is shown in Figure 12, the shape of the cross-section 1 of the special-shaped cross-section fiber of Example 13 is shown in Figure 13, the shape of the cross-section 1 of the special-shaped cross-section fiber of Example 14 is shown in Figure 14, the shape of the cross-section 1 of the special-shaped cross-section fiber of Example 15 is shown in Figure 15, the shape of the cross-section 1 of the special-shaped cross-section fiber of Example 16 is shown in Figure 16, the shape of the cross-section 1 of the special-shaped cross-section fiber of Example 17 is shown in Figure 17, the shape of the cross-section 1 of the special-shaped cross-section fiber of Example 18 is shown in Figure 18, and the shape of the cross-section 1 of the special-shaped cross-section fiber of Example 19 is shown in Figure 19.

[0121] 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.

[0122] The materials, softening points, linear density, length, content of the main fibers and bonding fibers used in Examples 1 to 19 and Comparative Example 1, as well as the shape of the cross-section 1 of the special-shaped cross-section fiber, the perimeter coefficient of the cross-section 1 of the special-shaped cross-section fiber, the number of grooves 10 of the special-shaped cross-section fiber, the ratio of the width w at the widest point of the groove 10 to the diameter D of the circumscribed circle 100 of the cross-section 1 of the special-shaped cross-section fiber (w / D in Tables 1 and 2), the ratio of the depth h at the deepest point of the groove 10 to the diameter D of the circumscribed circle 100 of the cross-section 1 of the special-shaped cross-section fiber (h / D in Tables 1 and 2), 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 and transverse tensile strength of the non-woven fabric are shown in Tables 1 and 2.

[0123] 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; and the perimeter modulus of the cross section 1 of special-shaped cross-section fibers is measured in accordance with FZ / T 50002-2013.

[0124] Table 1 Note: The content in Table 1 refers to the mass percentage of the fiber in the non-woven fabric; "PE / PP" in Table 1 refers to PE / PP two-component sheath-core fiber, with PE forming the core layer and PP forming the sheath layer.

[0125] In addition, the nonwoven fabrics of Examples 7 to 18 were prepared by referring to the nonwoven fabric preparation process of Example 1. The difference between Examples 7 to 18 and Example 1 is that the shapes of the special-shaped cross-section fibers used are different, as shown in Table 2. Except for the differences shown in Table 2, the other conditions are the same.

[0126] Table 2

[0127] It can be seen that compared with Comparative Example 1 (using two circular cross-section fibers instead of special-shaped cross-section fibers), the perimeter coefficient X is introduced in Examples 1 to 19. L Satisfy 1<X L The special-shaped cross-section fiber of ≤5 can significantly improve the strength of the non-woven fabric while maintaining a thin thickness of the non-woven fabric.

[0128] Among them, compared with Example 19 (the surface of the special-shaped cross-section fiber has no grooves), the special-shaped cross-section fiber in Example 6 has grooves, which can further improve the strength of the non-woven fabric.

[0129] Among them, compared with Example 18 (w / D<15%, h / D>75%), the special-shaped cross-section fibers in Examples 1 and Examples 7 to 17 satisfy w / D≥15%, h / D≤75%, which can further improve the strength of the nonwoven fabric.

[0130] 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, The invention comprises a main fiber, wherein the main fiber comprises a circular cross-section fiber and a shaped cross-section fiber; the perimeter coefficient of the cross section of at least part of the shaped cross-section fiber is X L , 1<X L ≤5.

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

3. The non-woven fabric according to claim 2, characterized in that, the grooves extend along the axial direction of the profiled cross-section fiber and penetrate the profiled cross-section fiber in the axial direction of the profiled cross-section fiber.

4. The non-woven fabric according to claim 2, characterized in that, the number of the grooves is one or more. When there are multiple grooves, the multiple grooves are distributed along the circumferential direction of the profiled cross-section fiber.

5. The non-woven fabric according to claim 2, characterized in that, the number of the grooves is less than or equal to 16.

6. The non-woven fabric according to claim 2, characterized in that, at least one of the following conditions is satisfied: 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 any one of claims 2-6, characterized in that, the shape of the cross-section of the profiled cross-section fiber includes a heart shape, a dumbbell shape, a crescent shape, a new moon shape, an incomplete circular ring shape, an incomplete circular shape, a clover shape, a polygon shape, a character shape or a plum blossom shape; Optionally, the incomplete circular shape includes a semi-circular ring shape or a two-thirds circular ring shape; Optionally, the incomplete circular shape includes a seven-eighths circular shape, a three-fourths circular shape or a two-thirds circular shape; Optionally, the clover shape includes a three-leaf clover shape or a four-leaf clover shape; Optionally, the polygon includes a multi-angle shape, and the multi-angle shape includes a triangular star shape, a four-angle star shape, a five-angle star shape, a six-angle star shape, an eight-angle star shape, a twelve-angle star shape or a sixteen-angle star shape; Optionally, the character shape includes a cross shape, a double cross shape, an I shape, a rice 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, a U shape, a V shape, a W shape, an X shape, a Y shape or a Z shape; Optionally, the plum blossom shape includes a four-petal plum blossom shape, a five-petal plum blossom shape or a six-petal plum blossom shape.

8. The non-woven fabric according to any one of claims 1-6, characterized in that, at least one of the following conditions is satisfied: a. The mass ratio of the profiled cross-section fiber to the main fiber is 5% to 60%; b. The mass ratio of the main fiber to the non-woven fabric is 60% to 85%.

9. The non-woven fabric according to any one of claims 1-6, characterized in that, at least one of the following conditions is satisfied: a. The linear density of the main fiber is less than or equal to 0.4 dtex; b. The length of the main fiber is 1 mm to 3 mm.

10. The non-woven fabric according to any one of claims 1-6, characterized in that, it further includes bonding fibers, and the softening point of the main fiber is greater than the softening point of the bonding fibers.

11. The non-woven fabric according to claim 10, characterized in that, at least one of the following conditions is satisfied: a. The difference between the softening point of the main fiber and the softening point of the bonding fiber is greater than or equal to 20 °C; b. The softening point of the bonding fiber is greater than or equal to 120 °C.

12. The non-woven fabric according to claim 10, characterized in that it satisfies at least one of the following conditions: a. The linear density of the bonding fiber is less than or equal to 0.8 dtex; b. The length of the bonding fiber is 1 mm to 3 mm.

13. The non-woven fabric according to claim 10, characterized in that the bonding fiber includes one or more of unstretched polyester fiber, polyvinylidene fluoride fiber, polyamide fiber, copolyamide fiber, polyolefin fiber, copolyester fiber, copolyamide fiber; Optionally, the unstretched polyester fiber includes at least one of polyethylene terephthalate or polybutylene terephthalate; Optionally, the polyolefin fiber includes one or more of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyethylene / polypropylene core-shell fiber, polyethylene / polyethylene terephthalate core-shell fiber, polyethylene / polybutylene terephthalate core-shell fiber; Optionally, the copolyester fiber includes at least one of CoPET or CoPBT; Optionally, the copolyamide fiber includes 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, PA6 / 66 / 11 / 12.

14. The non-woven fabric according to any one of claims 1-6, characterized in that at least one of the circular cross-section fiber and the profiled cross-section fiber includes one or more of polyester fiber, polyolefin fiber, polyamide fiber, polyimide fiber, polytetrafluoroethylene fiber, polyphenylene sulfide fiber, polyether ether ketone fiber, polyacrylonitrile fiber, polycarbonate fiber, aramid fiber; Optionally, the polyester fiber includes one or more of polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyisophthalic acid resin; Optionally, the polyolefin fiber includes one or more of polyethylene, polypropylene, polyvinyl chloride, polystyrene; Optionally, the polyamide fiber includes PA66.

15. The non-woven fabric according to any one of claims 1-6, characterized in that it satisfies at least one of the following conditions: a. The thickness of the non-woven fabric is 5 μm to 25 μm; b. The areal density of the non-woven fabric is 4 g / m 2 ~20 g / m 2 ; c. The density of the non-woven fabric is 0.5 g / cm 3 to 0.9 g / cm 3 .

16. A separator, characterized in that it includes the non-woven fabric according to any one of claims 1-15.

17. A battery, characterized in that it includes a positive electrode sheet, a negative electrode sheet and the separator according to claim 17, and the separator is located between the positive electrode sheet and the negative electrode sheet.

18. The battery according to claim 17, characterized in that the battery is a liquid battery, a semi-solid battery or a solid battery.

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