An alternating composite separator and winding method of cylindrical battery winding cell

Abstract

This invention relates to the field of battery components and their manufacturing processes, specifically to a method for winding an alternating composite separator and a cylindrical battery cell. The invention provides a method for winding an alternating composite separator and a cylindrical battery cell, comprising periodically composite-connected ceramic nonwoven membrane segments and separator segments, using an adhesive-free composite method. The ceramic nonwoven membrane segments and separator segments have the same thickness and width. The ceramic nonwoven membrane is composed of an ultrafine fiber substrate and a ceramic coating. The ultrafine fiber substrate has a diameter of 0.5~2μm and is prepared using a wet web-forming process. The ceramic coating is applied to one or both sides of the ultrafine fiber substrate, with a coating thickness of 1~3μm. The ceramic nonwoven membrane has a basis weight of 5~15g / m², a porosity of 60~75%, a pore size of 0.1~1μm, a tensile strength ≥5N / 5cm, and a temperature resistance ≥200℃. The separator is a microporous separator with a porosity of 40~70% and a temperature resistance of 120~150℃. This invention provides a method for winding an alternating composite separator and a cylindrical battery cell, which supports the cell and has a novel structure and simple process.

Description

Technical Field

[0001] This invention relates to the field of battery components and their manufacturing processes, specifically to an alternating composite separator and a winding method for cylindrical battery cells. Background Technology

[0002] Cylindrical lithium-ion batteries are widely used in new energy vehicles, portable electronic devices, and energy storage systems due to their high energy density, stable structure, and excellent cycle performance. The wound cell is the core component of a cylindrical battery. During the winding process, a central tube or central membrane is typically placed at the center of the core to support it, prevent collapse, and ensure electrolyte flow and gas expulsion.

[0003] Currently, the existing technologies for core center support mainly include the following structures: First, an independent center tube is used, which requires separate assembly, resulting in cumbersome procedures, increased production costs, and gaps easily form between the center tube and the electrode sheet and diaphragm, affecting the core's density; Second, a center film is wound to form a support cylinder, but the center film is mostly PP / PE film, which has weak support and is prone to shrinkage, softening, and collapse when immersed in electrolyte for a long time, and its structure is simple; Third, the negative electrode sheet extension section is pre-wound into a tube to replace the center tube, which requires special processing of the negative electrode sheet, making the process complex. Summary of the Invention

[0005] To address the technical problems in existing technologies where the structure of the core center support affects the core's density, provides weak support, or complicates the process, this invention provides a winding method for an alternating composite separator and cylindrical battery cell, which supports the core and features a novel structure and simple process.

[0006] This invention provides an alternating composite membrane, comprising periodically composited ceramic nonwoven membrane segments and membrane segments, using an adhesive-free composite method. The ceramic nonwoven membrane segments and membrane segments have the same thickness and width. The ceramic nonwoven membrane is composed of an ultrafine fiber substrate and a ceramic coating. The ultrafine fiber substrate has a diameter of 0.5~2μm and is prepared using a wet web forming process. The ceramic coating is applied to one or both sides of the ultrafine fiber substrate, with a coating thickness of 1~3μm. The basis weight of the ceramic nonwoven membrane is 5~15g / m³. 2 The porosity is 60~75%, the pore size is 0.1~1μm, the tensile strength is ≥5N / 5cm, and the temperature resistance is ≥200℃; the diaphragm is a microporous diaphragm with a porosity of 40~70% and a temperature resistance of 120~150℃.

[0007] Furthermore, the microfiber substrate is one of PET, PP, PVA or aramid; the ceramic coating is Al2O3, SiO2 or ZrO2 nano-ceramic slurry.

[0008] Furthermore, the ceramic nonwoven membrane segment and the diaphragm segment are composited by hot-melt micro-melting composite, with a temperature of 60~120℃ and a composite time of 0.1~0.3s.

[0009] Furthermore, the connection strength between the ceramic nonwoven membrane segment and the diaphragm segment is ≥0.35N / 25mm.

[0010] Furthermore, the thickness of both the ceramic nonwoven membrane segment and the diaphragm segment is 8~16μm.

[0011] This invention provides a method for winding cylindrical battery cells using alternating composite separators, comprising the following steps: S1, preparing a ceramic nonwoven membrane and a separator; S2, periodically bonding ceramic nonwoven membrane segments and separator segments online, adding an intermittent bonding station at the end of the separator production line, using the separator segment as the first unwinding station and the ceramic nonwoven membrane segment roll as the second unwinding station, cutting the separator to a fixed length and stretching it open using a periodic cutting mechanism, cutting the ceramic nonwoven membrane segments to a set length using the same periodic cutting mechanism, conveying the cut composite ceramic nonwoven membrane segments to align with the separator, and then using an intermittent pressing mechanism to instantaneously press the ceramic nonwoven membrane segments onto the surface of the continuously moving separator segment substrate, achieving periodic alternating bonding of the ceramic nonwoven membrane segments and separator segments; S3, winding the alternately bonded composite separator after tension control and correction treatment, obtaining an integrated alternating layer of "ceramic nonwoven membrane segment → separator segment" in an infinite cycle. Composite separator roll; S4, Install the alternating composite separator roll, positive electrode roll, and negative electrode roll onto the corresponding unwinding station of the winding machine. The front end of the alternating composite separator is a ceramic nonwoven membrane segment, which can cover the positive and negative electrodes. Start the winding machine and first feed the front end ceramic nonwoven membrane segment of the alternating composite separator into the winding needle. Wind until the ceramic nonwoven membrane forms a self-supporting hollow support hole, which serves as the center support of the core. After the ceramic nonwoven membrane segment is wound, the winding machine continues to run, and the separator segment of the alternating composite separator enters the winding process. At the same time, the positive and negative electrodes are fed in simultaneously. The positive and negative electrodes are separated by the separator segment. The conventional winding sequence centered on the support hole is continued until the core diameter required by the set process is reached, and then the separator, positive electrode, and negative electrode are cut. S5, After winding, apply a stop adhesive to the end of the core to complete the preparation of the cylindrical battery winding cell.

[0012] Furthermore, in step S1, the ceramic nonwoven membrane is prepared by: the ceramic nonwoven membrane being composed of an ultrafine fiber substrate and a ceramic coating, wherein the ultrafine fiber substrate is one of PET, PP, PVA or aramid, the diameter of the ultrafine fiber substrate is 0.5~2μm, and it is prepared by a wet web forming process; the ceramic coating is an Al2O3, SiO2 or ZrO2 nano-ceramic slurry, which is coated on one or both sides of the ultrafine fiber substrate, and the coating thickness is 1~3μm.

[0013] Furthermore, the basis weight of the ceramic nonwoven membrane is 5~15 g / m³. 2 The porosity is 60~75%, the pore size is 0.1~1μm, the tensile strength is ≥5N / 5cm, and the temperature resistance is ≥200℃; the diaphragm is PP, PE or PP / PE composite microporous diaphragm, the diaphragm porosity is 40~70%, and the temperature resistance is 120~150℃.

[0014] Furthermore, in step S2, the composite method in which the ceramic nonwoven membrane segment is instantaneously pressed onto the surface of the continuously moving diaphragm segment substrate is hot-melt micro-melting composite.

[0015] Furthermore, the connection strength between the ceramic nonwoven membrane segment and the diaphragm segment is ≥0.35N / 25mm.

[0016] The beneficial effects of this invention are as follows: This invention has excellent support performance and good stability: the ceramic nonwoven membrane segment and the diaphragm segment are designed with equal thickness, and the core thickness is uniform after winding. The ceramic nonwoven membrane segment, with its own rigidity and stiffness, can not only form a self-supporting hollow support hole in the center of the core, but also form support points at the alternating positions of each layer of the core, preventing the core from deforming due to the deformation of the center hole. This invention provides excellent electrolyte wetting, exhibiting no swelling, degradation, or pulverization in lithium battery electrolyte (EC / DMC / EMC+LiPF6) environments, demonstrating superior corrosion resistance and long-term stable use. Furthermore, the porous structure (porosity 60~75%) of the ceramic nonwoven membrane segment effectively adsorbs electrolyte and promotes electrolyte wetting, while simultaneously forming a flow channel to accelerate the discharge of formation gas. This solves the problems of poor flow conduction and uneven electrolyte wetting in conventional central membranes, thereby improving the cycle performance and rate performance of the battery cell. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of an embodiment of the alternating composite diaphragm of the present invention; Figure 2 This is a process flow diagram of one embodiment of the alternating composite diaphragm of the present invention; Figure 3 A process flow diagram for one embodiment of the production of wound battery cells; Figure 4 This is a schematic diagram of the structure of an embodiment of the alternating composite diaphragm wound battery cell of the present invention; Figure 5This is a schematic diagram of the structure of an embodiment of the alternating composite diaphragm wound battery cell of the present invention; Figure 6 This is a schematic diagram of the structure of an embodiment of the alternating composite diaphragm wound battery cell of the present invention.

[0020] Explanation of main reference numerals: 1-Ceramic nonwoven membrane segment, 2-Composite junction, 3-Separator segment, 4-Positive electrode sheet, 5-Negative electrode sheet, 6-Support hole. Detailed Implementation

[0022] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0023] like Figure 1 As shown, this invention provides an alternating composite diaphragm, comprising a periodically composited ceramic nonwoven membrane segment 1 and a diaphragm segment 3, wherein the composite method is an adhesive-free composite method. The ceramic nonwoven membrane segment 1 and the diaphragm segment 3 have the same thickness and width, and both have a thickness of 8-16 μm. In embodiments of this invention, the thicknesses of the ceramic nonwoven membrane segment 1 and the diaphragm segment 3 can be 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, etc. The ceramic nonwoven membrane is composed of a microfiber substrate and a ceramic coating. The diameter of the microfiber substrate is 0.5-2 μm. In embodiments of this invention, the diameter of the microfiber substrate can be selected as 0.5 μm, 1 μm, 1.5 μm, 2 μm, etc. The microfiber substrate is prepared using a wet web-forming process, and the microfiber substrate is one of PET, PP, PVA, or aramid. The ceramic coating is an Al2O3, SiO2, or ZrO2 nano-ceramic slurry, applied to one or both sides of the ultrafine fiber substrate. The coating thickness is 1-3 μm. In embodiments of this invention, the ceramic coating thickness can be selected as 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, etc. The basis weight of the ceramic nonwoven membrane is 5-15 g / m³. 2 In embodiments of the present invention, the basis weight of the ceramic nonwoven membrane can be 5 g / m³. 2 7g / m 2 9g / m 2 11g / m 2 13g / m 2The porosity of the ceramic nonwoven membrane is 60-75%, with a density of 15 g / m², etc. In embodiments of the present invention, the porosity can be 60%, 68%, 70%, 73%, 75%, etc. The pore size of the ceramic nonwoven membrane is 0.1-1 μm, etc. In embodiments of the present invention, the pore size can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, etc. The tensile strength of the ceramic nonwoven membrane is ≥5 N / 5 cm, etc. In embodiments of the present invention, the tensile strength can be 5 N / 5 cm, 8 N / 5 cm, 10 N / 5 cm, 12 N / 5 cm, 15 N / 5 cm, 18 N / 5 cm, 20 N / 5 cm, 25 N / 5 cm, 30 N / 5 cm, 40 N / 5 cm, 50 N / 5 cm, etc. The ceramic nonwoven membrane has a temperature resistance ≥200℃. In embodiments of the present invention, the temperature resistance of the ceramic nonwoven membrane can be 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, etc. The separator is a microporous separator with a porosity of 40~70%. In embodiments of the present invention, the porosity of the separator can be 40%, 50%, 60%, 70%, etc. The separator has a temperature resistance of 120~150℃. In embodiments of the present invention, the temperature resistance of the separator can be 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, etc.

[0024] The ceramic nonwoven membrane segment 1 and the separator segment 3 are composited by hot-melt micro-melting composite. The hot-melt micro-melting composite temperature is 60~120℃, and the temperature is selected according to the materials of the ceramic nonwoven membrane and the separator. In the embodiments of the present invention, the hot-melt micro-melting composite temperature can be 60℃, 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, etc., and the composite time is 0.1~0.3s. In the embodiments of the present invention, the composite time of hot-melt micro-melting composite can be 0.1s, 0.2s, 0.3s, etc. In the embodiments of the present invention, selecting appropriate hot-melt composite temperature and composite time can ensure a firm composite without delamination. The connection strength between the ceramic nonwoven film segment 1 and the diaphragm segment 3 is ≥0.35N / 25mm, which meets the tensile requirements during the winding process. In the embodiments of the present invention, the connection strength between the ceramic nonwoven film segment 1 and the diaphragm segment 3 can be 0.35N / 25mm, 0.45N / 25mm, 0.55N / 25mm, 0.8N / 25mm, 1.0N / 25mm, 1.5N / 25mm, etc.

[0025] like Figure 2 and Figure 3 As shown, the present invention also provides a winding method for a cylindrical battery cell using an alternating composite separator, the steps of which include: S1. Preparation of ceramic nonwoven membranes and separators; the preparation method of the ceramic nonwoven membrane is as follows: the ceramic nonwoven membrane is composed of an ultrafine fiber substrate and a ceramic coating. The ultrafine fiber substrate is one of PET, PP, PVA or aramid, with a diameter of 0.5~2μm, and is prepared by a wet web forming process; the ceramic coating is an Al2O3, SiO2 or ZrO2 nano-ceramic slurry, coated on one or both sides of the ultrafine fiber substrate, with a coating thickness of 1~3μm. The basis weight of the ceramic nonwoven membrane is 5~15g / m³. 2 The porosity is 60~75%, the pore size is 0.1~1μm, the tensile strength is ≥5N / 5cm, and the temperature resistance is ≥200℃; the diaphragm is PP, PE or PP / PE composite microporous diaphragm, the diaphragm porosity is 40~70%, and the temperature resistance is 120~150℃.

[0026] S2, ceramic nonwoven membrane segment 1 and diaphragm segment 3 are periodically laminated online. An intermittent lamination station is added at the end of the diaphragm production line. Diaphragm segment 3 is used as the first unwinding station, and the roll of ceramic nonwoven membrane segment 1 is used as the second unwinding station. The diaphragm is cut to a fixed length and stretched by a periodic cutting mechanism. The ceramic nonwoven membrane segment 1 is then cut to a set length by the same periodic cutting mechanism. The cut composite ceramic nonwoven membrane segments are conveyed and aligned with the diaphragm. Then, an intermittent pressing mechanism instantly presses the ceramic nonwoven membrane segment 1 onto the surface of the continuously moving diaphragm segment 3 substrate. The part where ceramic nonwoven membrane segment 1 and diaphragm segment 3 are laminated is the lamination junction 2, realizing the periodic alternating bonding of ceramic nonwoven membrane segment 1 and diaphragm segment 3. The lamination method of instantaneously pressing ceramic nonwoven membrane segment 1 onto the surface of the continuously moving diaphragm segment 3 substrate is hot-melt micro-melting lamination. The connection strength between ceramic nonwoven membrane segment 1 and diaphragm segment 3 is ≥0.35N / 25mm.

[0027] S3, after alternating lamination of the composite diaphragm, tension control and correction treatment are performed and then the roll is wound up to obtain an integrated alternating composite diaphragm roll material with infinite cycle of "ceramic nonwoven membrane segment 1 → diaphragm segment 3".

[0028] S4, the alternating composite separator roll, the positive electrode sheet 4 roll, and the negative electrode sheet 5 roll are respectively installed at the corresponding unwinding positions of the winding machine. The front end of the alternating composite separator is a ceramic nonwoven membrane segment 1, and the alternating composite separator can cover the positive and negative electrodes. Start the winding machine, first feed the front end ceramic nonwoven membrane segment 1 of the alternating composite separator into the winding needle, and wind it until the ceramic nonwoven membrane forms a self-supporting hollow support hole 6, such as... Figure 5 and Figure 6 As shown, the support hole 6 serves as the center support for the core. After the ceramic nonwoven membrane section 1 is wound into shape, the winding machine continues to run, and the separator section 3 of the alternating composite separator enters the winding process. At the same time, the positive electrode 4 and the negative electrode 5 are fed in simultaneously. The positive and negative electrodes are separated by the separator section 3. The conventional winding sequence centered on the support hole 6 is used to continue winding until the core diameter required by the set process is reached, after which the separator, positive electrode 4, and negative electrode 5 are cut.

[0029] S5. After winding, apply a terminating adhesive to the end of the core to complete the preparation of the cylindrical battery winding cell.

[0030] Example 1 is an embodiment of an alternating composite diaphragm of the present invention: An alternating composite separator is an integral continuous roll material, consisting of a ceramic nonwoven membrane segment 1 and a separator segment 3 arranged periodically and continuously along the length of the roll material to form an infinite loop structure of "ceramic nonwoven membrane segment 1 → separator segment 3 → ceramic nonwoven membrane segment 1 → separator segment 3...". The ceramic nonwoven membrane segment 1 and the separator segment 3 are both 13μm thick and 115mm wide, which are compatible with the width of the cylindrical battery electrode.

[0031] Ceramic nonwoven membrane segment 1 is an ultrathin ceramic nonwoven membrane, composed of an ultrafine aramid substrate and an Al2O3 nano-ceramic coating. The ultrafine aramid fibers have a diameter of 1 μm and are prepared using a wet web-forming process. The Al2O3 nano-ceramic coating is applied to one side of the ultrafine aramid substrate, with a coating thickness of 2 μm. Key performance indicators of ceramic nonwoven membrane segment 1 (aramid substrate): basis weight 10 g / m³. 2 Porosity 65%, pore size 0.5μm, tensile strength 7.5N / 5cm (aramid fiber has higher strength than PP / PET, providing better support), temperature resistance 280℃ (far exceeding PP / PET substrate, significantly improving high-temperature safety), insulation resistance 10 Ω·cm. 15 The Ω·cm value indicates that the corrosion resistance in lithium battery electrolyte (EC / DMC / EMC+LiPF6) is superior to that of conventional PP / PET-based ceramic nonwoven membranes. Separator section 3 is a PP microporous membrane with a porosity of 55% and a temperature resistance of 130℃, meeting the isolation requirements for the positive and negative electrodes of lithium-ion batteries.

[0032] The ceramic nonwoven membrane segment 1 and the diaphragm segment 3 are connected by thermal bonding with an overlap width of 3mm. The bonding is adhesive-free and pollution-free, and the connection strength is ≥0.35N / 25mm, which meets the tensile requirements during the winding process. Because aramid fiber is resistant to high temperature, the thermal bonding temperature is set to 110℃ (to match the stability of the aramid substrate and the micro-melting bonding requirements of the PP diaphragm surface layer), and the bonding time is 0.2s to ensure a firm bonding without delamination.

[0033] In this embodiment, the preparation method of the alternating composite diaphragm adopts an online periodic composite process at the end of the diaphragm production line. The specific steps are as follows: Base membrane preparation: Polypropylene raw materials were melt extruded, longitudinally stretched, transversely stretched and heat-set to obtain a continuous PP microporous membrane segment 3 substrate with a thickness of 13μm and a width of 115mm. Preparation of ceramic nonwoven film: Using a wet web forming process, ultrafine aramid fibers are made into a fiber suspension (aramid fibers need to undergo surface activation treatment first, and 0.3wt% silane coupling agent is added to improve the adhesion to the ceramic coating). After papermaking, dehydration, and drying, Al2O3 nano-ceramic slurry is coated, and then hot-pressed at 120℃ (aramid is resistant to high temperature, and the hot-pressing temperature is 20℃ higher than that of PP / PET substrate to ensure the density of the coating), and slit to obtain 1 roll of aramid-based ceramic nonwoven film with a thickness of 13μm and a width of 115mm. Online periodic lamination: An intermittent lamination station is added at the end of the diaphragm production line. The aramid-based ceramic nonwoven film segment 1 roll is used as the second unwinding station. The ceramic nonwoven film segment 1 is cut into 100mm lengths by a periodic cutting mechanism. Then, the ceramic nonwoven film segment 1 is instantly pressed onto the surface of the continuously moving diaphragm segment 3 substrate by an intermittent pressing mechanism. A thermal lamination method is adopted (thermal lamination temperature 110℃, adapted to the high temperature resistance of the aramid substrate and the micro-melting requirements of the PP diaphragm, lamination time 0.2s) to form an alternating lamination structure. Finished product: After tension control and correction treatment, the alternately laminated composite diaphragm is directly wound up to obtain an integrated alternating composite diaphragm roll material with an infinite cycle of "ceramic nonwoven membrane segment 1 → diaphragm segment 3".

[0034] Example 2 is an embodiment of the winding method for cylindrical battery cells of the present invention: A cylindrical battery winding cell using the alternating composite separator in Example 1, such as Figure 4 The core body comprises an alternating composite separator, a positive electrode 4, and a negative electrode 5, integrally formed through a winding process. During winding, the alternating composite separator is used as the single incoming material and is directly wound from beginning to end without the need for additional central tubes, central membranes, or electrode extension treatments. The alternating composite separator in the core body forms a "ceramic nonwoven membrane segment 1 → separator segment 3" from the inner to the outer ring. The specific steps of the winding process for the cylindrical battery cell in this embodiment are as follows: Material preparation: Install the alternating composite separator roll, positive electrode sheet 4 roll, and negative electrode sheet 5 roll onto the corresponding unwinding station of the winding machine, ensuring that the front end of the alternating composite separator is the aramid-based ceramic nonwoven membrane segment 1, and that the ceramic nonwoven membrane segment 1 and the separator segment 3 alternate continuously without breakage; the width of the positive electrode sheet 4 and the negative electrode sheet 5 is designed according to the 46120 process, and the width of the alternating composite separator ensures that the positive and negative electrodes of the roll core are covered; Center support forming: Start the winding machine, first feed the front end aramid substrate ceramic nonwoven membrane segment 1 of the alternating composite diaphragm into the winding needle (5mm in diameter), and wind it until the aramid substrate ceramic nonwoven membrane is completed, forming a self-supporting hollow support hole 6. This support cylinder replaces the traditional center tube / center membrane in the existing technology and plays the role of core center support. Cell body winding: After the ceramic nonwoven membrane section 1 is wound into shape, the winding machine continues to run, and the separator section 3 of the alternating composite separator enters the winding process. At the same time, the positive electrode 4 and the negative electrode 5 are fed in simultaneously. The positive and negative electrodes are separated by the separator section 3. The conventional winding sequence centered on the support hole 6 is used to continue winding until the set core diameter process requirement is met. Then the separator, positive electrode 4, and negative electrode 5 are cut. Finishing and fixing: After the winding is completed, the termination adhesive is applied to the end of the core to complete the preparation of the cylindrical battery winding cell. After the winding core is prepared, the positive and negative electrode tabs are flattened and a short-circuit test is performed before proceeding to the next process.

[0035] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. An alternating composite separator, characterized by, It includes a periodically composite ceramic nonwoven membrane segment and a diaphragm segment, which are composited in an adhesive-free manner. The ceramic nonwoven membrane segment and the diaphragm segment have the same thickness and width. The ceramic nonwoven membrane is composed of an ultrafine fiber substrate and a ceramic coating. The ultrafine fiber substrate has a diameter of 0.5~2μm and is prepared by a wet web forming process. The ceramic coating is applied to one or both sides of the ultrafine fiber substrate, and the coating thickness is 1~3μm. The basis weight of ceramic nonwoven membrane is 5~15g / m³. 2 The porosity is 60~75%, the pore size is 0.1~1μm, the tensile strength is ≥5N / 5cm, and the temperature resistance is ≥200℃; The diaphragm is a microporous diaphragm with a porosity of 40-70% and a temperature resistance of 120-150℃.

2. The alternating composite diaphragm as described in claim 1, characterized in that, The microfiber substrate is one of PET, PP, PVA or aramid; The ceramic coating is an Al2O3, SiO2, or ZrO2 nano-ceramic slurry.

3. The alternating composite diaphragm as described in claim 1, characterized in that, The ceramic nonwoven membrane segment and the diaphragm segment are composited by hot-stamping micro-melting. The hot-stamping micro-melting temperature is 60~120℃ and the composite time is 0.1~0.3s.

4. The alternating composite diaphragm as described in claim 1, characterized in that, The connection strength between the ceramic nonwoven membrane segment and the diaphragm segment is ≥0.35N / 25mm.

5. The alternating composite diaphragm as described in claim 1, characterized in that, The thickness of both the ceramic nonwoven membrane segment and the diaphragm segment is 8~16μm.

6. A winding method of a cylindrical battery winding cell using an alternating type composite separator, characterized by the steps of include: S1, to prepare ceramic nonwoven membranes and separators; S2, ceramic nonwoven film segments and diaphragm segments are periodically laminated online. An intermittent lamination station is added at the end of the diaphragm production line. The diaphragm segment is used as the first unwinding station, and the ceramic nonwoven film segment roll is used as the second unwinding station. The diaphragm is cut to a fixed length and stretched by a periodic cutting mechanism. The ceramic nonwoven film segment is cut to a set length by a periodic cutting mechanism. The laminated ceramic nonwoven film of the cut segment is conveyed and aligned with the diaphragm. Then, the ceramic nonwoven film segment is instantly pressed onto the surface of the continuously moving diaphragm segment substrate by an intermittent pressing mechanism, so as to realize the periodic alternating lamination of ceramic nonwoven film segments and diaphragm segments. S3, after the composite diaphragm is alternately laminated, it is wound up after tension control and correction treatment to obtain an integrated alternating composite diaphragm roll material with infinite cycle of "ceramic nonwoven membrane segment → diaphragm segment". S4. The alternating composite separator roll, positive electrode roll, and negative electrode roll are respectively installed at the corresponding unwinding stations of the winding machine. The front end of the alternating composite separator is a ceramic nonwoven membrane segment, which can cover the positive and negative electrodes. The winding machine is started, and the front end ceramic nonwoven membrane segment of the alternating composite separator is fed into the winding needle and wound until the ceramic nonwoven membrane forms a self-supporting hollow support hole, which serves as the center support of the core. After the ceramic nonwoven membrane segment is wound into shape, the winding machine continues to run, and the separator segment of the alternating composite separator enters the winding process. At the same time, the positive and negative electrodes are fed in simultaneously. The positive and negative electrodes are separated by the separator segment. The conventional winding sequence centered on the support hole is continued until the core diameter required by the set process is reached, and then the separator, positive electrode, and negative electrode are cut. S5. After winding, a stop adhesive is applied to the end of the core to complete the preparation of the cylindrical battery winding cell.

7. The winding method for a cylindrical battery cell using an alternating composite separator as described in claim 6, characterized in that, In step S1, the ceramic nonwoven membrane is prepared by the following method: the ceramic nonwoven membrane is composed of an ultrafine fiber substrate and a ceramic coating. The ultrafine fiber substrate is one of PET, PP, PVA or aramid, and the diameter of the ultrafine fiber substrate is 0.5~2μm. It is prepared by a wet web forming process. The ceramic coating is an Al2O3, SiO2 or ZrO2 nano-ceramic slurry, which is coated on one or both sides of the ultrafine fiber substrate, and the coating thickness is 1~3μm.

8. The winding method of a cylindrical battery wound cell employing an alternating type composite separator according to claim 7, wherein The basis weight of ceramic nonwoven membrane is 5~15g / m³. 2 The porosity is 60~75%, the pore size is 0.1~1μm, the tensile strength is ≥5N / 5cm, and the temperature resistance is ≥200℃; the diaphragm is PP, PE or PP / PE composite microporous diaphragm, the diaphragm porosity is 40~70%, and the temperature resistance is 120~150℃.

9. The winding method of a cylindrical battery winding cell employing an alternating type composite separator according to claim 6, wherein In step S2, the composite method in which the ceramic nonwoven membrane segment is instantaneously pressed onto the surface of the continuously moving diaphragm segment substrate is hot-melt micro-melting composite.

10. The winding method of a cylindrical battery winding cell employing an alternating type composite separator according to claim 6, wherein The connection strength between the ceramic nonwoven membrane segment and the diaphragm segment is ≥0.35N / 25mm.

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