JP2012221600A - Separator, and apparatus and method for manufacturing separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separator having high electrolyte absorbency, low ion resistance, high dendrite resistance, and high mechanical strength, and an apparatus and a method for manufacturing the separator.SOLUTION: The separator is made of a nonwoven nanofiber fabric including first nanofibers composed of polyolefin, and second nanofibers composed of polyvinylidene fluoride.

Description

  The present invention relates to a separator, a separator manufacturing apparatus, and a separator manufacturing method.

Conventionally, the separator which consists of nanofiber nonwoven fabric is known (for example, refer patent document 1). According to the conventional separator, since the average diameter and voids of the fibers are fine compared to a separator made of a general nonwoven fabric, it has high electrolyte absorption, low ionic resistance, and high dendrite resistance. A thin separator can be obtained. Such a separator can be suitably used for a battery (including a primary battery and a secondary battery), a capacitor (also referred to as a capacitor), and the like.
The “separator” in the present invention refers to a non-conductive separator. The “nanofiber” refers to a fiber made of a polymer material and having an average diameter of several nm to several thousand nm.

Special table 2009-510700 gazette

  However, in the technical field of separators, there is a demand for a separator having a high level of electrolyte absorption, low ionic resistance, high dendrite resistance, and high mechanical strength.

  Then, this invention is made | formed in view of an above-described subject, and it aims at providing the separator provided with high electrolyte solution absorptivity, low ion resistance, high dendrite resistance, and high mechanical strength at a high level. . Moreover, it aims at providing the separator manufacturing apparatus which can manufacture such a separator. Furthermore, it aims at providing the separator manufacturing method which can manufacture such a separator.

[1] The separator of the present invention is characterized by comprising a nanofiber nonwoven fabric having first nanofibers made of polyolefin and second nanofibers made of polyvinylidene fluoride.

  For this reason, according to the separator of the present invention, since it is made of a nanofiber nonwoven fabric, the average diameter of the fiber is fine compared to a separator made of a general nonwoven fabric, as in the case of a conventional separator, and a high electrolyte solution It has absorptivity, low ionic resistance and high dendrite resistance, and can be a separator having a thin total thickness.

  In addition, according to the separator of the present invention, the “first nanofiber made of polyolefin” having high stability and excellent mechanical strength and the “first nanofiber made of polyvinylidene fluoride” having excellent electrolyte absorbability, ion resistance and dendrite resistance. Therefore, it is possible to provide a separator having high electrolyte solution absorbability, low ion resistance, high dendrite resistance and high mechanical strength at a high level.

  In the separator of the present invention, various polyolefins can be used as the polyolefin, and polypropylene can be particularly preferably used. Further, for example, a mixed polyolefin having polypropylene as a main component and other polyolefin (for example, polybutene) as a subcomponent can also be suitably used.

[2] In the separator of the present invention, the average diameter of the first nanofibers is preferably larger than the average diameter of the second nanofibers.

  With such a configuration, it is possible to obtain a separator having higher electrolyte solution absorbability, lower ionic resistance, higher dendrite resistance, and higher mechanical strength.

[3] In the separator of the present invention, the average diameter of the first nanofibers is preferably in the range of 500 nm to 9000 nm.

By setting it as such a structure, it becomes possible to set it as a separator provided with sufficiently high mechanical strength.
In the present invention, the average diameter of the first nanofibers is in the range of 500 nm to 9000 nm because the mechanical strength of the separator cannot be sufficiently increased when the average diameter is smaller than 500 nm. This is because if the average diameter is larger than 9000 nm, it may be difficult to make the separator thin.
From the above viewpoint, the average diameter of the first nanofibers is more preferably in the range of 1000 nm to 7000 nm.

[4] In the separator of the present invention, the average diameter of the second nanofiber is preferably in the range of 50 nm to 1000 nm.

By setting it as such a structure, it becomes possible to set it as a separator provided with sufficiently high electrolyte solution absorptivity, sufficiently low ion resistance, and sufficiently high dendrite resistance.
In the present invention, the average diameter of the second nanofibers is in the range of 50 nm to 1000 nm because the production of the second nanofibers may be difficult when the average diameter is smaller than 50 nm. Yes, when the average diameter is larger than 1000 nm, due to the decrease in specific surface area, the electrolyte solution absorbability of the separator cannot be sufficiently increased, and the ionic resistance cannot be sufficiently decreased. This is because the dendrite resistance may not be sufficiently high.
From the above viewpoint, it is more preferable that the average diameter of the second nanofiber is in the range of 60 nm to 500 nm.

[5] In the separator of the present invention, the nanofiber nonwoven fabric preferably has a thickness in the range of 1 μm to 100 μm.

By setting it as such a structure, it becomes possible to set it as a sufficiently thin separator.
In the present invention, the nanofiber nonwoven fabric has a thickness in the range of 1 μm to 100 μm. If the thickness is less than 1 μm, the mechanical strength of the separator may not be sufficiently high. This is because if the thickness is greater than 100 μm, the ion resistance may not be sufficiently reduced.
From the above viewpoint, it is more preferable that the nanofiber nonwoven fabric has a thickness in the range of 10 μm to 40 μm.

[6] In the separator of the present invention, both the first nanofiber and the second nanofiber are preferably obtained by an electrospinning method.

  With such a configuration, a separator having a well-controlled fiber diameter and stable quality can be obtained.

[7] The separator manufacturing apparatus of the present invention includes a conveying device that conveys a long sheet, a raw material tank that stores a polymer solution that is a raw material of nanofibers, and a plurality of nozzles that discharge the polymer solution from an outlet. A separator manufacturing apparatus comprising: a nozzle unit having a collector; a collector disposed on a side from which the polymer solution is discharged from the nozzle; and a power supply device that applies a high voltage between the plurality of nozzles and the collector. The raw material tank includes a first raw material tank for storing a first polymer solution containing polyolefin and a second raw material tank for storing a second polymer solution containing polyvinylidene fluoride, The nozzle unit includes a plurality of first nozzles for discharging the first polymer solution as the plurality of nozzles. Characterized in that it comprises a plurality of second nozzles for ejecting the second polymer solution.

  According to the separator manufacturing apparatus of the present invention, the separator of the present invention (the separator described in the above [1] to [6]) can be manufactured using an electrospinning apparatus.

[8] In the separator manufacturing apparatus of the present invention, it is preferable that the first nozzle and the second nozzle are upward nozzles, and the collector is disposed above the nozzle unit.

  By adopting such a configuration, a droplet phenomenon (a phenomenon in which a lump of polymer solution that has not been spun from a downward nozzle adheres to a long sheet) as seen in a separator manufacturing apparatus that uses a downward nozzle. It is possible to produce a high-quality separator without generating it.

[9] In the separator manufacturing apparatus of the present invention, it is preferable to further include a heat retaining device for retaining the first raw material tank at a predetermined temperature within a range of 30 ° C to 100 ° C.

  By the way, since polyolefin has excellent chemical resistance and non-polar structure, its solubility in a solvent is low, and it may be difficult to stably keep the solution in a uniform liquid state. Therefore, it may be difficult to stably produce nanofibers made of general polyolefin. In contrast, by adopting the configuration as described above, the first polymer solution containing polyolefin can be stably kept in a uniform liquid state, and the first nanofibers made of polyolefin can be stabilized. It can be manufactured.

The reason why the predetermined temperature is in the range of 30 ° C. to 100 ° C. is that when the predetermined temperature is lower than 30 ° C., it may be difficult to completely dissolve the polyolefin in the solvent. When the predetermined temperature exceeds 100 ° C., the amount of evaporation of the solvent becomes too large, and it may be difficult to keep the concentration of polyolefin in the first polymer solution constant.
From the above viewpoint, it is more preferable to set the predetermined temperature within the range of 50 ° C to 90 ° C.

[10] In the separator manufacturing apparatus of the present invention, it is preferable that the heat retaining device retains the nozzle unit at a predetermined temperature within a range of 30 ° C to 100 ° C.

  By the way, if only the first raw material tank is kept warm and the other portions are not kept warm, the viscosity of the first polymer solution increases with the passage of time, and the discharge amount of the first polymer solution from the nozzle gradually decreases. As a result, it may be difficult to stably produce a large amount of first nanofibers having uniform quality. On the other hand, by adopting the configuration as described above, the viscosity of the first polymer solution does not increase over time, and the discharge amount of the first polymer solution from the nozzle gradually decreases. It wo n’t happen. For this reason, it becomes possible to manufacture the 1st nanofiber which has uniform quality stably in large quantities.

[11] The separator manufacturing method of the present invention includes a polymer solution preparation step of preparing a first polymer solution containing polyolefin and a second polymer solution containing polyvinylidene fluoride, and the first solution solution from the discharge ports of a plurality of first nozzles. 1 polymer solution is discharged, and the second polymer solution is discharged from discharge ports of a plurality of second nozzles, whereby the first nanofibers made of the polyolefin and the second nanofibers made of the polyvinylidene fluoride are electrospun. And a separator manufacturing process for manufacturing a separator made of a nanofiber nonwoven fabric.

  According to the separator manufacturing method of the present invention, the separator of the present invention (the separator described in the above [1] to [6]) can be manufactured by electrospinning.

It is a figure shown in order to demonstrate the separator 300 which concerns on embodiment. It is a figure shown in order to demonstrate the separator manufacturing apparatus 1 which concerns on embodiment. It is a figure shown in order to demonstrate the electrospinning apparatus 20 in embodiment. It is a flowchart of the separator manufacturing method which concerns on embodiment. It is an electron micrograph of the separator 300a which concerns on an Example. It is a front view of the separator manufacturing apparatus 2 which concerns on the modification 1. FIG. It is a front view of the separator manufacturing apparatus 3 which concerns on the modification 2. FIG.

  Hereinafter, the separator of the present invention, a separator manufacturing device, and a separator manufacturing method are explained based on an embodiment shown in a figure.

[Embodiment]
1. Configuration of Separator 300 According to Embodiment First, the configuration of the separator 300 according to the embodiment will be described.
Drawing 1 is a figure shown in order to explain separator 300 concerning an embodiment. FIG. 1A is a perspective view showing a separator 300 wound around a core material (not shown), and FIG. 1B is a schematic view showing an enlarged detail of the separator 300.

  As illustrated in FIG. 1, the separator 300 according to the embodiment includes a nanofiber nonwoven fabric having first nanofibers 310 made of polypropylene and second nanofibers 320 made of polyvinylidene fluoride. The nanofiber nonwoven fabric has a thickness in the range of 1 μm to 100 μm, for example, 30 μm.

  The average diameter of the 1st nanofiber 310 exists in the range of 500 nm-9000 nm, for example, is 5000 nm. The average diameter of the second nanofiber 320 is in the range of 50 nm to 1000 nm, for example, 100 nm. In the separator 300, the average diameter of the first nanofibers 310 is larger than the average diameter of the second nanofibers 320.

  The separator 300 is obtained by the separator manufacturing method according to the embodiment using the separator manufacturing apparatus 1 according to the embodiment described later. That is, as will be described later, the first nanofiber 310 and the second nanofiber 320 are obtained by an electrospinning method.

2. Configuration of Separator Manufacturing Apparatus 1 According to Embodiment Next, the configuration of the separator manufacturing apparatus 1 according to the embodiment will be described.
Drawing 2 is a figure shown in order to explain separator manufacture device 1 concerning an embodiment. FIG. 2A is a front view of the separator manufacturing apparatus 1, and FIG. 2B is a plan view of the separator manufacturing apparatus 1. In FIG. 2, some members are shown as cross-sectional views. This also applies to FIGS. 3, 6 and 7 described later.
FIG. 3 is a view for explaining the electrospinning apparatus 20 in the embodiment. 3A is a front view of the electrospinning apparatus 20, and FIG. 3B is a plan view of the periphery of the nozzle unit 110. FIG. In FIG. 3B, illustration of the first polymer solution recovery path 124 and the second polymer solution recovery path 134 is omitted.

  As shown in FIG. 2, the separator manufacturing apparatus 1 according to the embodiment includes a transport device 10, an electrospinning device 20, an air permeability measuring device 40, a transport speed control device 50 (not shown), and main control. A device 60 and a VOC processing device 70 are provided.

  The separator manufacturing apparatus 1 according to the embodiment includes four electrospinning apparatuses 20 arranged in series along a predetermined conveyance direction in which the long sheet W is conveyed as an electrospinning apparatus.

The conveyance device 10 conveys the long sheet W at a predetermined conveyance speed. The conveyance device 10 includes a feeding roller 11 that feeds out the long sheet W, a winding roller 12 that winds up the long sheet W, tension rollers 13 and 18 that adjust the tension of the long sheet W, a feeding roller 11 and a winding roller. And auxiliary rollers 14, 15, 16, and 17 located between the two. The feeding roller 11 and the take-up roller 12 are configured to be rotated by a drive motor (not shown).
The electrospinning apparatus 20 deposits the first nanofibers 310 and the second nanofibers 320 on the long sheet W being conveyed by the conveying apparatus 10. The detailed configuration of the electrospinning apparatus 20 will be described later.

The air permeability measuring device 40 measures the air permeability of the “long sheet W on which the nanofiber nonwoven fabric having the first nanofibers 310 and the second nanofibers 320 is deposited” (a composite sheet described later) by the electrospinning device 20. To do. As the air permeability measuring device 40, a general air permeability measuring device can be used.
The transport speed control device 50 controls the transport speed based on the air permeability measured by the air permeability measuring device 40.
The main control device 60 controls the “conveyance device 10, the electrospinning device 20, the air permeability measurement device 40, the conveyance speed control device 50, and the VOC processing device 70”.
The VOC processing device 70 burns and removes volatile components generated when nanofibers are deposited on the long sheet W.

Hereinafter, the configuration of the electrospinning apparatus 20 will be described in detail.
As shown in FIG. 3, the electrospinning apparatus 20 includes a housing 100, a nozzle unit 110, a collector 150, a power supply device 160, an auxiliary belt device 170, a first raw material tank 200, and a first supply device 210. A second raw material tank 220, a second supply device 230, and a heat retaining device 240. The electrospinning apparatus 20 discharges the first polymer solution and the second polymer solution from the discharge ports of a plurality of first nozzles 120 and a plurality of second nozzles 130, which will be described later, to overflow the first nanofibers 310 and the second nanofibers 310. The nanofiber 320 is electrospun.

The housing 100 is made of a conductor and is grounded.
The nozzle unit 110 includes a plurality of first nozzles 120, a plurality of second nozzles 130, a first polymer solution supply path 122, a second polymer solution supply path 132, a first polymer solution recovery path 124, and a second polymer solution recovery path 134. (Not shown). Each of the plurality of first nozzles 120 and the plurality of second nozzles 130 is an upward nozzle.
Although the nozzle unit 110 having various sizes and various shapes can be used in the separator manufacturing apparatus of the present invention, the nozzle unit 110 is, for example, a rectangle having a side of 0.5 m to 3 m when viewed from the top surface ( It has a size and shape that can be seen (including a square).

  The plurality of first nozzles 120 are a plurality of nozzles that discharge the polymer solution from the discharge port, and are for discharging the first polymer solution containing polypropylene. The interior of the first nozzle 120 is a cavity, and the cavity communicates with the cavity in the first polymer solution supply path 122. The first nozzle 120 discharges the first polymer solution upward from the discharge port. As a material constituting the first nozzle 120, a conductor can be used, and for example, copper, stainless steel, aluminum, or the like can be used.

The plurality of second nozzles 130 are a plurality of nozzles that discharge the polymer solution from the discharge port, and are for discharging the second polymer solution containing polyvinylidene fluoride. The interior of the second nozzle 130 is a cavity, and the cavity communicates with the cavity in the second polymer solution supply path 132. The plurality of second nozzles 130 have the same configuration as that of the plurality of first nozzles 120 with respect to configurations other than those described above.
In the present embodiment, the distance between the first nozzle 120 and the collector 150 and the distance between the second nozzle 130 and the collector 150 are equal. The present invention is not limited to this, and in order to change the average diameter of the first nanofiber and the average diameter of the second nanofiber, the distance between the first nozzle and the collector, the second nozzle and the collector, The distance between the first nozzle and the collector may be different (for example, the distance between the first nozzle and the collector is shortened).

By the way, the 1st polymer solution supply path | route 122 and the 2nd polymer solution supply path | route 132 each have a protrusion part, as shown in FIG.3 (b), and each protrusion part is combining in uneven | corrugated shape.
As shown in FIG. 3B, the first nozzle 120 is disposed on the protruding portion of the first polymer solution supply path 122. The second nozzle 130 is disposed on the protruding portion of the second polymer solution supply path 132. For this reason, the plurality of first nozzles 120 and the plurality of second nozzles 130 are alternately arranged along the traveling direction of the long sheet.
The first nozzle 120 and the second nozzle 130 are arranged at a pitch of 1.5 cm to 6.0 cm, for example. The total number of the plurality of first nozzles 120 and the plurality of second nozzles 130 is, for example, 36 (6 × 6 when arranged in the same vertical and horizontal directions) to 21904 (148 when arranged in the same vertical and horizontal numbers) X148).

  The first polymer solution supply path 122 has a cavity inside, and supplies the first polymer solution from the first raw material tank 200 to the first nozzle 120 via the cavity. The first polymer solution supply path 122 has a connection portion with the first supply device 210, and is connected to the pipe 212 of the first supply device 210 at the connection portion.

  The second polymer solution supply path 132 also has a cavity inside, and supplies the second polymer solution from the second raw material tank 220 to the second nozzle 130 via the cavity inside. The second polymer solution supply path 132 has a connection portion with the second supply device 230, and is connected to the pipe 232 of the second supply device 230 at the connection portion.

  Although the detailed explanation is omitted, the first polymer solution recovery path 124 is formed of a receiving part, a groove part, and a lid part. The second polymer solution recovery path 134 has a similar configuration. The first polymer solution recovery path 124 recovers the first polymer solution that has overflowed from the discharge port of the first nozzle 120. Further, the second polymer solution recovery path 134 recovers the second polymer solution that has overflowed from the discharge port of the second nozzle 130.

  The collector 150 is disposed on the side where the first polymer solution and the second polymer solution are discharged from the first nozzle 120 and the second nozzle 130, that is, above the nozzle unit 110. The collector 150 is made of a conductor and is attached to the housing 100 via an insulating member 152 as shown in FIG.

The power supply device 160 applies a high voltage between the first nozzle 120 and the second nozzle 130 and the collector 150. The positive electrode of the power supply device 160 is connected to the collector 150, and the negative electrode of the power supply device 160 is connected to the nozzle unit 110 via the housing 100. That is, in this embodiment, the voltage applied between the first nozzle 120 and the collector 150 is equal to the voltage applied between the second nozzle 130 and the collector 150.
The present invention is not limited to the above. For example, in order to change the average diameter of the first nanofibers and the average diameter of the second nanofibers, a voltage applied between the first nozzle and the collector is used. And the voltage applied between the second nozzle and the collector can be different (the voltage applied between the first nozzle and the collector is made lower).

  The auxiliary belt device 170 includes an auxiliary belt 172 that rotates in synchronization with the conveyance speed of the long sheet W, and five auxiliary belt rollers 174 that assist the rotation of the auxiliary belt 172. Of the five auxiliary belt rollers 174, one or more auxiliary belt rollers are drive rollers, and the remaining auxiliary belt rollers are driven rollers. Since the auxiliary belt 172 is disposed between the collector 150 and the long sheet W, the long sheet W is smoothly conveyed without being attracted to the collector 150 to which a positive high voltage is applied. become.

  The first raw material tank 200 stores a first polymer solution that is a raw material of the first nanofibers 310. As shown in FIG. 3A, the first raw material tank 200 has a stirring device 202 for preventing separation and coagulation of the first polymer solution. A pipe 212 of a first supply device 210 is connected to the first raw material tank 200.

  The first supply device 210 includes a pipe 212 that allows the first polymer solution to pass therethrough and a valve 214 that controls a supply operation, and supplies the first polymer solution stored in the first raw material tank 200 to the first polymer solution of the nozzle unit 110. Supply to path 122. In addition, the 1st supply apparatus and the 2nd supply apparatus mentioned later should just be at least 1 per nozzle unit.

  The second raw material tank 220 stores a second polymer solution that is a raw material of the second nanofiber 400. The second raw material tank 220 includes an agitation device 222 for preventing separation and coagulation of the second polymer solution. A pipe 232 of the second supply device 230 is connected to the second raw material tank 220.

  The second supply device 230 includes a pipe 232 that allows the second polymer solution to pass therethrough and a valve 234 that controls the supply operation, and supplies the second polymer solution stored in the second raw material tank 220 to the second polymer solution of the nozzle unit 110. Supply to path 132.

The heat retaining device 240 keeps the first raw material tank 200, the first supply device 210, and the nozzle unit 110 at a predetermined temperature in the range of 30 ° C to 100 ° C.
Although the detailed description by illustration is abbreviate | omitted for the heat retention apparatus 240, the 1st heater which heats the 1st raw material tank 200, the 2nd heater which heats the 1st supply apparatus 210, the 3rd heater which heats the nozzle unit 110, The first temperature sensor for measuring the temperature of the first raw material tank 200, the second temperature sensor for measuring the temperature of the first supply device 210, the third temperature sensor for measuring the temperature of the nozzle unit 110, and the first temperature And a temperature control device that controls the temperature by adjusting the outputs of the first heater, the second heater, and the third heater based on the detection results of the sensor, the second temperature sensor, and the third temperature sensor. The predetermined temperature is determined by the average molecular weight of polypropylene, the type of solvent used, the composition of the first polymer solution, and the like.

3. Description of Separator Manufacturing Method According to Embodiment Next, the separator manufacturing method according to the embodiment will be described.
FIG. 4 is a flowchart of the separator manufacturing method according to the embodiment.

  As shown in FIG. 4, the separator manufacturing method according to the embodiment includes a polymer solution manufacturing step S1 and a separator manufacturing step S2. The separator manufacturing method according to the embodiment is a method for manufacturing the separator 300 according to the embodiment using the separator manufacturing apparatus 1 described above.

S1. Polymer Solution Preparation Step The polymer solution preparation step is a step of preparing a first polymer solution containing polypropylene and a second polymer solution containing polyvinylidene fluoride. Hereinafter, the case of the first polymer solution and the case of the second polymer solution will be described separately.

(A) Production of first polymer solution In the first raw material tank 200, polypropylene as a raw material is dissolved in a solvent to produce a first polymer solution. At this time, stirring is carried out while keeping the temperature at 50 ° C. to 100 ° C., more preferably 60 ° C. to 80 ° C. by the heat insulating device 30.

Examples of the solvent include acetone, chloroform, ethanol, isopropanol, methanol, toluene, tetrahydrofuran, water, benzene, benzyl alcohol, 1,4-dioxane, propanol, carbon tetrachloride, cyclohexane, cyclohexanone, dichloromethane, phenol, pyridine, and trichloroethane. , Acetic acid, N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N, N-dimethylacetamide (DMAc), 1-methyl-2-pyrrolidone (NMP), ethylene carbonate (EC), propylene carbonate (PC ), Dimethyl carbonate (DMC), acetonitrile (AN), N-methylmorpholine-N-oxide, butylene carbonate (BC), 1,4-butyrolactone (BL), diethyl carbonate (DEC), diethyl ether (DEE), 1 , 2-Dimet Sietane (DME), 1,3-dimethyl-2-imidazolidinone (DMI), 1,3-dioxolane (DOL), ethyl methyl carbonate (EMC), methyl formate (MF), 3-methyloxazolidine-2-one (MO), methyl propionate (MP), 2-methyltetrahydrofuran (MeTHF), sulfolane (SL), HFIP, xylene, methylcyclohexane, decahydronaphthalene (Decalin), methyl ethyl ketone (MEK), dichlorobenzene (DCB), etc. Can be used. A solvent can be used individually or in mixture.
Various additives can also be used for adjusting electrical conductivity, viscosity, and the like.

  During this time, the first temperature sensor measures the temperature of the first raw material tank 200 and transmits the measurement result to the temperature control device. The temperature control device controls the temperature of the first raw material tank 200 (that is, the temperature of the first polymer solution) by adjusting the output of the first heater based on the detection result of the first temperature sensor.

(B) Production of Second Polymer Solution In the second raw material tank 220, polyvinylidene fluoride as a raw material is dissolved in a solvent to produce a second polymer solution.

Examples of the solvent include acetone, chloroform, ethanol, isopropanol, methanol, toluene, tetrahydrofuran, water, benzene, benzyl alcohol, 1,4-dioxane, propanol, carbon tetrachloride, cyclohexane, cyclohexanone, dichloromethane, phenol, pyridine, and trichloroethane. , Acetic acid, N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N, N-dimethylacetamide (DMAc), 1-methyl-2-pyrrolidone (NMP), ethylene carbonate (EC), propylene carbonate (PC ), Dimethyl carbonate (DMC), acetonitrile (AN), N-methylmorpholine-N-oxide, butylene carbonate (BC), 1,4-butyrolactone (BL), diethyl carbonate (DEC), diethyl ether (DEE), 1 , 2-Dimet Sietane (DME), 1,3-dimethyl-2-imidazolidinone (DMI), 1,3-dioxolane (DOL), ethyl methyl carbonate (EMC), methyl formate (MF), 3-methyloxazolidine-2-one (MO), methyl propionate (MP), 2-methyltetrahydrofuran (MeTHF), sulfolane (SL), HFIP, xylene, methylcyclohexane, decahydronaphthalene (Decalin), methyl ethyl ketone (MEK), dichlorobenzene (DCB), etc. Can be used. A solvent can be used individually or in mixture.
Various additives can also be used for adjusting electrical conductivity, viscosity, and the like.

In the present embodiment, the above steps are performed so that the viscosity of the first polymer solution is increased (so that the solution is a thick solution). By doing in this way, the average diameter of the 1st nanofiber can be made larger than the average diameter of the 2nd nanofiber.
Also, the average diameter of the first nanofibers is made larger than the average diameter of the second nanofibers by increasing the electrical conductivity of the second polymer solution using an additive for adjusting the electrical conductivity of the solution. be able to.

S2. Separator manufacturing process In the separator manufacturing process, the first polymer solution is discharged from the discharge ports of the plurality of first nozzles 120, and the second polymer solution containing polyvinylidene fluoride is discharged from the discharge ports of the plurality of second nozzles 130. Thus, the first nanofiber 310 made of polypropylene and the second nanofiber 320 made of polyvinylidene fluoride are electrospun on the long sheet W, and the first nanofiber 310 made of polyolefin and the second nanofiber made of polyvinylidene fluoride are electrospun. A separator made of a nanofiber nonwoven fabric having fibers 320 is produced. Hereinafter, the process will be described in detail.

  First, the first polymer solution produced in the first raw material tank 200 is supplied to the first polymer solution supply path 122 through the pipe 212, and the second polymer solution produced in the second raw material tank 220 is supplied through the pipe 232 to the second polymer solution. Supply to path 132. In the first supply device 210, the transfer operation of the first polymer solution from the first raw material tank 200 is controlled by the valve 214, and in the second supply device 230, the second polymer from the second raw material tank 220 is controlled by the valve 234. Control the transfer operation of the solution.

  During this time, the second temperature sensor measures the temperature of the pipe 212 and transmits the measurement result to the temperature control device. The temperature control device controls the temperature of the pipe 212 by adjusting the output of the second heater based on the detection result of the second temperature sensor.

  Next, the long sheet W is set on the conveying device 10, and then the long sheet W is conveyed from the feeding roller 11 toward the take-up roller 12 at a predetermined conveying speed V while being long in each electrospinning device 20. First nanofibers and second nanofibers are sequentially deposited on the length sheet W. During this time, the third temperature sensor measures the temperature of the nozzle unit 110 and transmits the measurement result to the temperature control device. The temperature control device controls the temperature by adjusting the output of the third heater based on the detection result of the third temperature sensor. In this way, a composite sheet is manufactured in which “a separator 300 made of a nanofiber nonwoven fabric having first nanofibers 310 made of polypropylene and second nanofibers 320 made of polyvinylidene fluoride” is deposited on a long sheet. The composite sheet is wound around the winding roller 12.

  Finally, the separator 300 made of the nanofiber nonwoven fabric is collected from the composite sheet.

  Below, the manufacturing conditions in the separator manufacturing method according to the embodiment are exemplarily shown.

  As the long sheet W, non-woven fabrics, woven fabrics, knitted fabrics, papers and the like made of various materials can be used. The long sheet W may have a thickness of, for example, 5 μm to 500 μm. The length of the long sheet W can be, for example, 10 m to 10 km.

Air permeability P of the composite sheet to be produced can be set, for example, ^{0.15cm 3 / cm 2 / s~200cm 3} / cm 2 / s. The conveyance speed V can be set to 0.2 m / min to 100 m / min, for example. The voltage applied to the nozzle, collector 150 and nozzle unit 110 can be set to 10 kV to 80 kV.

  The temperature in the spinning area can be set to 50 ° C., for example, except in the vicinity of the nozzle unit 110. The humidity of the spinning area can be set to 30%, for example.

  Hereinafter, effects of the separator 300, the separator manufacturing apparatus 1, and the separator manufacturing method according to the embodiment will be described.

  According to the separator 300 according to the embodiment, since it is made of a nanofiber nonwoven fabric, the average diameter of the fiber is fine compared to a separator made of a general nonwoven fabric, and the electrolyte absorption is high, as in the case of a conventional separator. , Low ionic resistance, high dendrite resistance, and a thin separator with a total thickness.

  Further, according to the separator 300 according to the embodiment, the first nanofiber 310 made of polyolefin (polypropylene) having high stability and excellent mechanical strength, and polyvinylidene fluoride excellent in electrolyte solution absorbability, ion resistance, and dendrite resistance. Since it consists of the nanofiber nonwoven fabric which has the 2nd nanofiber 320 which consists of, it becomes possible to set it as a separator provided with high electrolyte solution absorptivity, low ionic resistance, high dendrite resistance, and high mechanical strength at a high level.

  In addition, according to the separator 300 according to the embodiment, since the average diameter of the first nanofibers 310 is larger than the average diameter of the second nanofibers 320, high electrolyte solution absorbability, low ionic resistance, high dendrite resistance, and high A separator having higher mechanical strength can be obtained.

  Moreover, according to the separator 300 which concerns on embodiment, since the average diameter of the 1st nanofiber 310 exists in the range of 500 nm-9000 nm, it becomes possible to set it as a separator provided with sufficiently high mechanical strength.

  Moreover, according to the separator 300 which concerns on embodiment, since the average diameter of the 2nd nanofiber 320 exists in the range of 50 nm-1000 nm, sufficiently high electrolyte solution absorptivity, sufficiently low ion resistance, and sufficiently high dendrite It becomes possible to set it as the separator provided with tolerance.

  Moreover, according to the separator 300 which concerns on embodiment, since the thickness of a nanofiber nonwoven fabric exists in the range of 1 micrometer-100 micrometers, it becomes possible to set it as a sufficiently thin separator.

  Moreover, according to the separator 300 which concerns on embodiment, since both the 1st nanofiber 310 and the 2nd nanofiber 320 were obtained by the electrospinning method, it has a well-controlled fiber diameter and is stable It is possible to obtain a separator having the quality.

  According to the separator manufacturing apparatus 1 according to the embodiment, the first raw material tank 200 for storing the first polymer solution containing polyolefin and the second raw material for storing the second polymer solution containing polyvinylidene fluoride. And the nozzle unit 110 includes a plurality of first nozzles 120 for discharging one polymer solution and a plurality of second nozzles 130 for discharging the second polymer solution. It becomes possible to manufacture the separator 300 which concerns on embodiment using this.

  Further, according to the separator manufacturing apparatus 1 according to the embodiment, the first nozzle 120 and the second nozzle 130 are composed of upward nozzles, so that a droplet phenomenon as seen in the case of a separator manufacturing apparatus using downward nozzles is generated. Without making it possible, it is possible to manufacture a high-quality separator.

  Moreover, according to the separator manufacturing apparatus 1 which concerns on embodiment, since the 1st raw material tank 200 is equipped with the heat retention apparatus 240 which heat-retains to the predetermined temperature which exists in the range of 30 to 100 degreeC, it is 1st polymer containing polyolefin. The solution can be stably maintained in a uniform liquid state, and the first nanofibers 310 made of polyolefin can be stably manufactured.

  Moreover, according to the separator manufacturing apparatus 1 which concerns on embodiment, since the heat retention apparatus 240 heats the nozzle unit 110 also to the predetermined temperature which exists in the range of 30 to 100 degreeC, even if time passes, 1st polymer solution The viscosity of the liquid does not increase, and the discharge amount of the first polymer solution from the nozzle does not gradually decrease. For this reason, it becomes possible to manufacture the 1st nanofiber 310 which has uniform quality stably in large quantities.

  According to the separator manufacturing method according to the embodiment, the polymer solution preparation step S1 for preparing the first polymer solution containing polyolefin and the second polymer solution containing polyvinylidene fluoride, the first nanofibers 310 made of polyolefin, and the polyolefin are prepared. The separator 300 according to the embodiment can be manufactured by electrospinning since the second nanofiber 320 made of vinylidene is electrospun and the separator manufacturing step S2 is manufactured to manufacture the separator 300 made of nanofiber nonwoven fabric. .

[Example]
FIG. 5 is an electron micrograph of the separator 300a according to the example.

  In the examples, the separator 300a defined by the present invention was actually manufactured, and the structure of the separator 300a was confirmed.

The manufacturing method of the separator 300a which concerns on an Example is as follows.
First, as a polymer solution preparation step, a first polymer solution and a second polymer solution were prepared.

(A) Preparation of first polymer solution The first polymer solution was a raw material syndiotactic polypropylene (sPP, weight average molecular weight (Mw): 127,000, number average molecular weight (Mn): 54000, Mw / Mn = 2.35. (Purchased from Sigma-Aldrich) and a mixed solvent of cyclohexane: acetone: dimethylformamide = 8: 1: 1. The raw material and solvent were stirred at 60 ° C., and after confirming dissolution of the raw material, the solution was cooled to 30 ° C. The solution concentration was adjusted to 6 wt%.

(B) Preparation of second polymer solution A second polymer solution was prepared using polyvinylidene fluoride (PVDF, purchased from Sigma-Aldrich) as a raw material and a mixed solvent of acetone: dimethylformamide = 1: 1. did. The raw materials and the solvent were stirred at room temperature, and dissolution of the raw materials was confirmed. The solution concentration was adjusted to 24 wt%.

Next, as a separator manufacturing process, a separator 300a made of a nanofiber nonwoven fabric was manufactured by an electrospinning method.
The electrospinning conditions were common to both the first polymer solution and the second polymer solution, the nozzle-collector distance (TCD) was 15 cm, and the applied voltage was 10 kV.

As shown in FIG. 5, the separator 300 a manufactured as described above includes first nanofibers (thick fibers) made of polypropylene and second nanofibers (thin fibers) made of polyvinylidene fluoride. It has been confirmed that the separator is made of a nanofiber nonwoven fabric.
In the separator 300a, the average diameter of the first nanofibers was approximately 5000 nm, and the average diameter of the second nanofibers was approximately 300 nm.

  Thus, the structure of the separator 300a defined by the present invention could be confirmed.

  As mentioned above, although this invention was demonstrated based on said embodiment, this invention is not limited to said embodiment. The present invention can be implemented in various forms without departing from the spirit thereof, and for example, the following modifications are possible.

(1) The number, positional relationship, and size of each component in the above embodiment are examples, and the present invention is not limited to this.

(2) Although the separator 300 which concerns on the said embodiment shall be manufactured using the separator manufacturing apparatus 1 which concerns on embodiment, this invention is not limited to this. The separator of the present invention can be manufactured using various separator manufacturing apparatuses.

(3) Although the separator 300 which concerns on the said embodiment shall be manufactured with the separator manufacturing method which concerns on embodiment, this invention is not limited to this. The separator of the present invention can be manufactured using various separator manufacturing methods.

(4) Although the separator manufacturing method which concerns on the said embodiment shall be performed using the separator manufacturing apparatus 1 which concerns on embodiment, this invention is not limited to this. The separator manufacturing method of this invention can be performed using various separator manufacturing apparatuses provided with an electrospinning apparatus.

(5) The separator manufacturing apparatus of the present invention may further include an apparatus for separating and collecting the separator from the composite sheet. FIG. 6 is a front view of the separator manufacturing apparatus 2 according to the first modification. FIG. 7 is a front view of the separator manufacturing apparatus 3 according to the second modification. The separator manufacturing apparatuses 2 and 3 include a separator separation and recovery apparatus 80 that is an apparatus for separating and recovering the separator from the composite sheet. By setting it as such a structure, it becomes possible to manufacture a separator continuously, without taking the effort which collect | recovers the separator which consists of nanofiber nonwoven fabrics from the composite sheet once wound up by the winding roller.

(6) In the separator 300, the separator manufacturing apparatus 1 and the separator manufacturing method according to the above embodiment, polypropylene is used as the polyolefin, but the present invention is not limited to this. A polyolefin other than polypropylene may be used as the polyolefin, or a mixed polyolefin obtained by mixing two or more kinds of polyolefins may be used.

(7) The separator manufacturing apparatus 1 according to the above embodiment uses the air permeability measuring apparatus 40, but the present invention is not limited to this. For example, another measuring device (for example, using a camera) that measures the thickness may be used. Further, the air permeability measuring device may not be used. In this case, a non-breathable material such as a film can be used as the long sheet.

(8) In the separator manufacturing apparatus of this invention, you may use a nozzle unit provided with a tubular 1st polymer solution supply apparatus and a 2nd polymer solution supply apparatus as a nozzle unit.

(9) In the above embodiment, the separator manufacturing apparatus of the present invention has been described by taking the separator manufacturing apparatus 1 including four electrospinning apparatuses as the electrospinning apparatus 20 as an example. However, the present invention is not limited to this. Absent. For example, the present invention can be applied to a separator manufacturing apparatus including three or less or five or more electrospinning apparatuses.

(10) In the above embodiment, the separator manufacturing apparatus of the present invention has been described using the electrospinning apparatus in which the positive electrode of the power supply device 160 is connected to the collector 150 and the negative electrode of the power supply device 160 is connected to the nozzle unit 110. However, the present invention is not limited to this. For example, the present invention can be applied to a separator manufacturing apparatus including an electrospinning apparatus in which a positive electrode of a power supply device is connected to a nozzle unit and a negative electrode of the power supply device is connected to a collector.

(11) In each of the above embodiments, the present invention has been described using the separator manufacturing apparatus 1 in which one nozzle unit is disposed in one electrospinning apparatus. However, the present invention is not limited to this. . For example, the present invention can be applied to a separator manufacturing apparatus in which two nozzle units are disposed in one electrospinning apparatus, or the present invention is applied to a separator manufacturing apparatus in which two or more nozzle units are disposed. You can also

  In this case, the nozzle arrangement pitch can be made the same for all nozzle units, or the nozzle arrangement pitch can be made different for each nozzle unit. Moreover, the height position of a nozzle unit can also be made the same by all the nozzle units, and the height position of a nozzle unit can also be varied by each nozzle unit.

1, 2, 3 ... Separator manufacturing device, 10, 19 ... Conveying device, 11 ... Feeding roller, 12 ... Winding roller, 13, 18, 88 ... Tension roller, 14, 15, 16, 17, 86 ... Auxiliary roller, DESCRIPTION OF SYMBOLS 20 ... Electrospinning device, 40 ... Air permeability measuring device, 60 ... Main control device, 70 ... VOC processing device, 80 ... Separator separation and recovery device, 82 ... Separator take-up roller, 84 ... Separation roller, 91, 92 ... Drive roller , 100 ... casing, 110 ... nozzle unit, 120 ... first nozzle, 122 ... first polymer solution supply path, 124 ... first polymer solution recovery path, 130 ... second nozzle, 132 ... second polymer solution recovery path, 150 ... collector, 152 ... insulator, 160 ... power supply, 170 ... auxiliary belt device, 172 ... auxiliary belt, 174 Auxiliary belt roller, 200 ... first raw material tank, 202, 222 ... stirring device, 210 ... first supply device, 212,232 ... pipe, 214,234 ... valve, 220 ... second raw material tank, 230 ... second supply Device: 240 ... Insulating device, 300 ... Separator, 310 ... First nanofiber, 320 ... Second nanofiber, W, W2 ... Long sheet

Claims (11)

  A separator comprising a nanofiber nonwoven fabric having first nanofibers made of polyolefin and second nanofibers made of polyvinylidene fluoride. The separator according to claim 1, wherein
The average diameter of said 1st nanofiber is larger than the average diameter of said 2nd nanofiber, The separator characterized by the above-mentioned. The separator according to claim 2,
The first nanofiber has an average diameter in a range of 500 nm to 9000 nm. The separator according to claim 3,
The average diameter of said 2nd nanofiber exists in the range of 50 nm-1000 nm, The separator characterized by the above-mentioned. In the separator in any one of Claims 1-4,
The nanofiber nonwoven fabric has a thickness in the range of 1 μm to 100 μm. In the separator in any one of Claims 1-5,
The first nanofiber and the second nanofiber are both obtained by an electrospinning method. A conveying device for conveying a long sheet;
A raw material tank for storing a polymer solution as a raw material of nanofibers;
A nozzle unit having a plurality of nozzles for discharging the polymer solution from a discharge port;
A collector disposed on the side from which the polymer solution is discharged from the nozzle;
A separator manufacturing apparatus comprising a power supply device that applies a high voltage between the plurality of nozzles and the collector,
The raw material tank comprises a first raw material tank for storing a first polymer solution containing polyolefin, and a second raw material tank for storing a second polymer solution containing polyvinylidene fluoride,
The nozzle unit includes, as the plurality of nozzles, a plurality of first nozzles for discharging the first polymer solution and a plurality of second nozzles for discharging the second polymer solution. Separator manufacturing equipment. In the separator manufacturing apparatus according to claim 7,
The first nozzle and the second nozzle are composed of upward nozzles,
The separator manufacturing apparatus, wherein the collector is disposed above the nozzle unit. In the separator manufacturing apparatus according to claim 7 or 8,
A separator manufacturing apparatus, further comprising a heat retaining device that retains the first raw material tank at a predetermined temperature within a range of 30 ° C to 100 ° C. In the separator manufacturing apparatus according to claim 9,
The said heat retention apparatus heats the said nozzle unit also to the predetermined temperature which exists in the range of 30 to 100 degreeC, The separator manufacturing apparatus characterized by the above-mentioned. A polymer solution preparation step of preparing a first polymer solution containing polyolefin and a second polymer solution containing polyvinylidene fluoride;
By discharging the first polymer solution from the discharge ports of the plurality of first nozzles and discharging the second polymer solution from the discharge ports of the plurality of second nozzles, the first nanofibers made of the polyolefin and the polyfluorination A separator manufacturing process for manufacturing a separator made of a nanofiber nonwoven fabric having the first nanofiber made of polyolefin and the second nanofiber made of polyvinylidene fluoride by electrospinning the second nanofiber made of vinylidene. The separator manufacturing method characterized by including.