Manufacturing device of lithium ion diaphragm

Abstract

The utility model discloses a manufacturing device of a lithium ion diaphragm, which comprises an extraction mechanism and a secondary stretching mechanism, and further comprises an edge cutting mechanism, the edge cutting mechanism is used for cutting edges of the diaphragm to obtain an edge-cut diaphragm, and the edge cutting mechanism is arranged on the rear side of the extraction mechanism; the edge ironing mechanism is used for heating the edge of the edge cutting diaphragm, the edge ironing mechanism is located between the edge cutting mechanism and the secondary stretching mechanism, and the edge ironing mechanism comprises a heating unit arranged at the edge position of the edge cutting diaphragm. According to the manufacturing device of the lithium ion diaphragm, the transverse tensile strength of the diaphragm is improved while the tensile ratio of the diaphragm is high, and the trimmed diaphragm is not easy to pull apart.

Description

TECHNICAL FIELD

[0001] The utility model belongs to diaphragm production technical field, more particularly in a kind of lithium ion diaphragm manufacturing device. BACKGROUND

[0002] Lithium ion battery is usually mainly composed of positive pole, negative pole, diaphragm, electrolyte, battery shell. In lithium ion battery structure, diaphragm is one of key inner layer components. The main role of diaphragm is to separate the positive pole and negative pole of battery, prevent positive pole and negative pole from directly contacting and short circuiting, while also making electrolyte ion can smoothly pass in the process of battery charging and discharging, form electric current.

[0003] The silicon negative pole theoretical specific capacity is as high as 3592mAh g -1 , is superior to the graphite negative pole material of current popularity, and is expected to realize leap in battery energy density, electric automobile's cruising range and efficiency and the capacity of portable electronic equipment. The main challenge of silicon as mainstream negative pole material lies in its serious volume expansion (up to 300%) in lithiation process, and this expansion and subsequent shrinkage in attenuation process will exert huge mechanical stress on silicon particles, resulting in silicon negative crushing and loss of electrical connectivity.

[0004] An easily overlooked factor of silicon negative pole (Si) failure: mechanical closing of diaphragm. The volume expansion of silicon generates local compressive stress on commercial polyethylene diaphragm, leading to pore collapse, and this structural damage weakens the transport capacity of lithium ion on diaphragm, aggravates redox heterogeneity and silicon pulverization. Simulation results show that diaphragm needs large Young's modulus to withstand the volume expansion of silicon.

[0005] In order to improve the Young's modulus of diaphragm, the draw ratio of diaphragm needs to be improved, and the diaphragm is cut transversely after extraction and before the second stretching to reduce the inlet width. In the case of unchanged outlet, the transverse stretching of diaphragm is greatly improved. For example, when the outlet width of diaphragm is 6000mm, if the inlet width is 4000mm, the draw ratio (diaphragm outlet width / inlet width) is 1.50 times, if the inlet width is 3200mm by cutting edge, the draw ratio is 1.88. The draw ratio of diaphragm after extraction and cutting edge is improved, and the strength and air permeability of diaphragm are obviously improved.

[0006] After extraction, the paraffin oil in the diaphragm is extracted, and the diaphragm becomes thin. If the diaphragm is not cut after extraction, the area of 20-60mm on both sides of the diaphragm is clamped by the chain clamp of the first stretching device, and the area is subjected to high temperature in the first stretching device and is closed. When the diaphragm is stretched in the second stretching mechanism, the edge clamped by the chain clamp is supported by the thick edge, which is equivalent to line stress, and the middle part of the diaphragm is not easy to break. However, in order to improve the stretching ratio of the diaphragm to improve the strength of the diaphragm, the thick edge of the edge of the diaphragm is usually cut before entering the second transverse stretching device after extraction, but this will make the edge area clamped by the chain clamp thinner when the diaphragm is stretched in the second stretching mechanism, which is equivalent to point stress. When the stretching ratio is large, the diaphragm may be broken due to stretching, and the diaphragm may be broken. Content of the utility model

[0007] Therefore, the utility model provides a kind of manufacturing device of lithium ion diaphragm, while guaranteeing that the diaphragm is stretched with high ratio, improve the transverse tensile strength of diaphragm, and the diaphragm after cutting edge is not easy to be torn.

[0008] To achieve the above object, the utility model adopts the following technical scheme:

[0009] A kind of manufacturing device of lithium ion diaphragm, including extraction mechanism and secondary stretching mechanism, the manufacturing device further includes edge cutting mechanism, it is used to cut edge to the diaphragm to obtain cutting edge diaphragm, the edge cutting mechanism is set in the rear side of the extraction mechanism;Edge ironing mechanism, it is used to heat the edge of the cutting edge diaphragm, the edge ironing mechanism is located between the edge cutting mechanism and secondary stretching mechanism, the edge ironing mechanism includes heating unit being set in the edge position of the cutting edge diaphragm.

[0010] In a preferred embodiment, the edge ironing mechanism further includes cooling unit being set in the edge position of the cutting edge diaphragm, the heating unit and the cooling unit are arranged along the diaphragm conveying direction and the heating unit and the cooling unit are arranged in the same level.

[0011] In a preferred embodiment, the heating unit and the cooling unit are located below the diaphragm.

[0012] In a preferred embodiment, the cooling unit is located at the right side of the heating unit.

[0013] In a preferred embodiment, the heating unit includes heating roller, the heating roller has first fluid passage, and heat-conducting oil is passed in the first fluid passage;The cooling unit has cooling roller, and the cooling roller has second fluid passage, and cooling water is passed in the second fluid passage.

[0014] In a preferred embodiment, the number of the heating roller and the cooling roller is multiple.

[0015] In a preferred embodiment, the heating unit comprises a heating sheet, and the cooling unit comprises a cooling sheet.

[0016] In a preferred embodiment, the heating unit comprises an infrared heater, and the cooling unit comprises a cooling sheet.

[0017] In a preferred embodiment, the edge cutting mechanism comprises a knife holder and a cutting knife arranged on the knife holder, and the cutting knife is used to cut the edge of the diaphragm.

[0018] In a preferred embodiment, the manufacturing device further comprises a plurality of conveying rollers, and the plurality of conveying rollers are located between the edge cutting mechanism and the edge sealing mechanism.

[0019] The above scheme is adopted in the utility model, and the utility model has the following advantages compared with the prior art.

[0020] The manufacturing device of the lithium ion diaphragm increases the tensile ratio of the diaphragm, performs edge cutting treatment on the edge of the diaphragm before entering the secondary stretching mechanism, reduces the width of the diaphragm when the diaphragm enters the secondary stretching mechanism to improve the Young's modulus of the diaphragm, then performs edge sealing treatment on the edge-cut diaphragm, specifically, the edge of the diaphragm after edge cutting is heated and then cooled, which makes the edge of the diaphragm thicker, and the diaphragm is not easy to be torn when the diaphragm is stretched for the second time, that is, the transverse tensile strength of the diaphragm is higher while the tensile ratio of the diaphragm is high, and the diaphragm is not easy to be torn in the secondary stretching mechanism. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical scheme of the utility model, the drawings needed in the embodiment description will be briefly introduced below, and obviously, the drawings in the following description are only some embodiments of the utility model, and other drawings can be obtained according to the drawings for those skilled in the art without creative labor.

[0022] Fig. 1 It is a manufacturing method flowchart of the lithium ion diaphragm.

[0023] Fig. 2 It is a schematic view of the edge sealing mechanism, and the edge-cut diaphragm is not shown.

[0024] Fig. 3 It is a schematic view of the edge sealing mechanism.

[0025] Among them,

[0026] 1, edge-cut diaphragm; 2, heating roller; 3, cooling roller. DETAILED DESCRIPTION

[0027] The preferred embodiments of the utility model are described in detail below with reference to the drawings, so that the advantages and features of the utility model can be more easily understood by the person skilled in the art. It should be noted that the description of these embodiments is used to help understand the utility model, but does not constitute a limitation on the utility model. In addition, the technical features involved in each embodiment of the utility model described below can be combined with each other as long as they do not conflict with each other.

[0028] Referring to Figs. 1 to 3 As shown in the figure, the manufacturing method of the lithium ion diaphragm comprises the following steps performed sequentially: a first stretching step, an extraction step, a trimming step, a hemming step, a second stretching step, and a winding step.

[0029] Further, the trimming step specifically comprises trimming the edges of the extracted diaphragm to obtain a trimmed diaphragm 1, and the hemming step comprises first heating the edges of the trimmed diaphragm by using a heating unit, and then cooling the edges of the trimmed diaphragm by using a cooling unit. The hemming of the present embodiment is to first heat and then cool the edges of the diaphragm, rather than to first heat and then cool the entire diaphragm. If the entire diaphragm is first heated and then cooled, the entire diaphragm will be shrunk or thickened, affecting the use effect. The width of the trimming is greater than 0 and less than 500 mm, and the width of the hemming is 40-60 mm. The greater the width of the trimming, the smaller the inlet width of the diaphragm, and the greater the stretching ratio. Here, the "width" refers to the direction perpendicular to the running direction of the diaphragm.

[0030] Further, in the hemming step, a heating roller 2 is used to heat the edges of the trimmed diaphragm 1, and a cooling roller 3 is used to cool the edges of the trimmed diaphragm 1. Referring to Fig. 2 and Fig. 3 As shown in the figure, the heating roller 2 has eight, and the cooling roller 3 has two. The diaphragm of the trimmed diaphragm 1 has oppositely arranged front and rear edges, and the front and rear edges are respectively provided with four heating rollers 2 and one cooling roller 3. The heating roller 2 and the cooling roller 3 are in contact with the edges of the trimmed diaphragm 1. The heating temperature of the heating roller 2 for the trimmed diaphragm 1 is 130-150℃, and the cooling temperature of the cooling roller 3 for the trimmed diaphragm 1 is 0-20℃. The heating time of the edges of the trimmed diaphragm 1 is 3-5 seconds, and the cooling time of the edges of the trimmed diaphragm 1 is 1-2 seconds. In the specific operation, the edges of the trimmed diaphragm 1 are first heated, the edges of the trimmed diaphragm 1 are shrunk by heat, the thickness of the edges is increased, and then cooled, so that the edges of the trimmed diaphragm 1 are relatively hard and have high tensile strength.

[0031] In the hemming step of other embodiments, a heating sheet or an infrared heater can also be used to heat the edges of the diaphragm, and a cooling sheet can be used to cool the edges of the diaphragm.

[0032] If the edge of the diaphragm is not cut, the middle of the diaphragm is not easy to break in the secondary stretching step, but the stretching is relatively low, the Young's modulus of the diaphragm is small, which leads to that the diaphragm cannot withstand the volume expansion of silicon. In order to overcome the above defects, the edge of the diaphragm is cut to improve the stretching ratio. However, after cutting, the edge is relatively thin, and the middle of the diaphragm is easy to be cut off in the secondary stretching process. In view of the above problems, the edge of the cut diaphragm is treated in this embodiment. According to Table 1, it can be seen that the diaphragm obtained by the manufacturing method of the embodiment has the same or even higher transverse tensile strength (TD) and needle puncture strength than that without cutting. This shows that the manufacturing method of the embodiment not only can ensure that the diaphragm has a relatively high stretching ratio, but also can avoid the phenomenon of diaphragm breakage caused by the thin edge in the secondary stretching process, and has high reliability.

[0033] Table 1 Comparison of diaphragm without cutting and diaphragm after edge treatment

[0034]

[0035]

[0036] The embodiment also provides a manufacturing device of lithium ion diaphragm, which comprises an extraction mechanism, a secondary stretching mechanism, a cutting mechanism and an edge treatment mechanism arranged between the extraction mechanism and the secondary stretching mechanism. The cutting mechanism is arranged at the rear side of the extraction mechanism, and the edge treatment mechanism is arranged between the cutting mechanism and the secondary stretching mechanism. The cutting mechanism is used for cutting the edge of the diaphragm to obtain a cut diaphragm 1. The cutting mechanism comprises a cutter holder and a cutting knife arranged on the cutter holder. The diaphragm is conveyed to the lower side of the cutter holder by a conveying roller after extraction. The cutting knife on the cutter holder cuts off the edge of the diaphragm. The cutting range is greater than 0 and less than 500 mm. The edge treatment mechanism comprises a heating unit and a cooling unit arranged at the edge position of the cut diaphragm 1. The heating unit and the cooling unit are arranged below the diaphragm 1, and the cooling unit is arranged at the right side of the heating unit. The heating unit and the cooling unit are arranged in the conveying direction of the diaphragm and are arranged in the same plane. Here, the conveying direction of the diaphragm refers to the running direction of the diaphragm, i.e. the left-right direction. Fig. 3 The edge of the diaphragm is cut off at the cutting mechanism to obtain the cut diaphragm 1. The cut diaphragm 1 is conveyed to the heating unit and the cooling unit by a plurality of conveying rollers to heat and cool the edge of the cut diaphragm 1.

[0037] Further, the heating unit has a heating roller 2, the heating roller 2 has a first fluid channel, heat-conducting oil is passed in the first fluid channel, the heat carried by the heating oil is used to heat the trimmed separator 1, the temperature of the heating oil is controlled by a mold temperature controller, the mold temperature controller controls the temperature of the heating oil to be between 130-150 DEG C; the cooling unit has a cooling roller 3, the cooling roller 3 has a second fluid channel, cooling water is passed in the second fluid channel, the cooling water is controlled by circulating and replacing water, because the trimmed separator 1 has relatively high heat after passing through the heating roller 2, the temperature of the cooling roller 3 is increased when the trimmed separator 1 passes through the cooling roller 3, therefore, the liquid in the cooling roller 3 needs to be circulated and replaced with cooling water to keep the temperature of the cooling roller 3 at 0-20 DEG C.

[0038] The lithium ion separator of the embodiment is trimmed to obtain a trimmed separator 1 after extraction, the trimmed separator 1 is conveyed to a plurality of parallel heating rollers 2, the heating rollers 2 heat the edges of the trimmed separator 1, the heating temperature is 130-150 DEG C, the holes on the heated separator are closed, the separator is heat-shrunk to thicken the separator, then the edges of the trimmed separator 1 after heating are cooled by a cooling roller 3. The trimmed separator 1 can reduce the inlet width of the separator into the secondary stretching mechanism to improve the stretching ratio of the separator, improve the Young's modulus of the separator, and avoid that the separator cannot withstand the volume expansion of silicon; the edges of the trimmed separator 1 are heated and then cooled to prevent the trimmed separator 1 from being torn in the secondary stretching process, that is, the manufacturing method of the lithium ion separator of the embodiment can not only ensure that the separator has a small inlet width to improve the stretching ratio, but also has high transverse tensile strength and is not easy to be torn and broken.

[0039] As shown in the specification and claims, the terms "comprise" and "include" only indicate the inclusion of the steps and elements explicitly identified, and these steps and elements do not constitute an exclusive list, and the method or device can also include other steps or elements. The term "and / or" used herein includes any combination of one or more related listed items.

[0040] It should be noted that, unless otherwise specified, when a certain feature is referred to as "fixed", "connected" to another feature, it can be directly fixed, connected to another feature, or indirectly fixed, connected to another feature. In addition, the up, down, left, right and other descriptions used in the utility model are only relative to the mutual position relationship of the components of the utility model in the drawings.

[0041] The above embodiment is only for illustrating the technical concept and characteristics of the utility model, is a preferred embodiment, the purpose is that the person skilled in the art can understand the content of the utility model and implement it, and cannot limit the protection scope of the utility model. Any equivalent transformation or modification according to the principle of the utility model should be covered in the protection scope of the utility model.

Claims

1. An apparatus for manufacturing a lithium ion separator comprising an extraction mechanism and a secondary stretching mechanism, characterized in that, The manufacturing device further comprises: a trimming mechanism for trimming the diaphragm to obtain a trimmed diaphragm, the trimming mechanism being disposed at the rear side of the extracting mechanism; a hemming mechanism for heating the edge of the trimmed diaphragm, the hemming mechanism being located between the trimming mechanism and the secondary stretching mechanism, the hemming mechanism comprising a heating unit disposed at the edge position of the trimmed diaphragm.

2. The manufacturing apparatus according to claim 1, characterized by The hemming mechanism further comprises a cooling unit disposed at the edge position of the trimmed diaphragm, the heating unit and the cooling unit being disposed along the diaphragm conveying direction and being disposed in the same level.

3. The manufacturing apparatus according to claim 2, wherein The heating unit and the cooling unit are located below the diaphragm.

4. The manufacturing apparatus according to claim 2, wherein The cooling unit is located at the right side of the heating unit.

5. The manufacturing apparatus according to claim 3, wherein The heating unit comprises a heating roller having a first fluid channel through which a heat-conducting oil is passed, and the cooling unit comprises a cooling roller having a second fluid channel through which cooling water is passed.

6. The manufacturing apparatus according to claim 5, wherein The number of the heating roller and the cooling roller is multiple.

7. The manufacturing apparatus according to claim 3, wherein The heating unit comprises a heating sheet, and the cooling unit comprises a cooling sheet.

8. The manufacturing apparatus according to claim 3, wherein The heating unit comprises an infrared heater, and the cooling unit comprises a cooling sheet.

9. The manufacturing apparatus according to claim 1, wherein The trimming mechanism comprises a knife holder and a trimming knife disposed on the knife holder, the trimming knife being used for cutting the edge of the diaphragm.

10. The manufacturing apparatus according to claim 8, wherein The manufacturing device further comprises multiple conveying rollers, the multiple conveying rollers being located between the trimming mechanism and the hemming mechanism.

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