Electrode insulating liquid supply device and electrode insulating liquid supply method

Abstract

The present invention relates to an apparatus for supplying an insulating liquid to form an insulating coating on an electrode of a battery, comprising: a storage tank storing the insulating liquid; a coating die head at which the insulating liquid is coated on the electrode; a supply line connected to the storage tank and supplying the insulating liquid to the coating die head; a pump installed on the supply line; a defoaming tank connected to the storage tank and supplying defoamed insulating liquid to the storage tank; a vacuum pump that eliminates bubbles of the insulating liquid in the defoaming tank by applying a vacuum to the defoaming tank; a bubble sensor installed on the supply line and sensing the generation of bubbles in the supply line in real time; and a controller that adjusts the operating conditions of the apparatus based on the amount of bubbles sensed by the bubble sensor. According to the present invention, pinhole defects of the insulating coating can be reduced by suppressing the mixing of bubbles in the insulating liquid supply line. The present invention also relates to a method for supplying insulating liquid to an electrode using the above-mentioned apparatus for supplying insulating liquid.

Description

Technical Field

[0001] The invention relates to a device for supplying insulating liquid to battery electrodes and a method for supplying insulating liquid.

[0002] This application claims the priority of Korean Patent Application No. 10-2020-0138326 filed on October 23, 2020 and Korean Patent Application No. 10-2021-0131148 filed on October 1, 2021, the contents of which are hereby incorporated as part of this specification. Background Art

[0003] As technology continues to develop and demand for mobile devices increases, demand for secondary batteries is also increasing rapidly. Among secondary batteries, lithium secondary batteries are widely used as energy sources for various electronic products and various mobile devices because they have high energy density and high operating voltage as well as excellent storage and life characteristics.

[0004] One of the main researches on these secondary batteries is to improve safety. Accidents related to battery safety are closely related to abnormally high temperature conditions caused by short circuits between the positive and negative electrodes. That is, under normal circumstances, the separator is located between the positive and negative electrodes to maintain electrical insulation, but in abnormal situations where the battery is overcharged or over-discharged, an internal short circuit occurs due to dendrite growth of the electrode material, or foreign objects such as nails, screws, etc., sharp objects penetrate the battery, or the battery is deformed by external forces, the existing separator is insufficient.

[0005] In addition, the separator formed of a microporous separator mainly composed of a polyolefin resin has a heat resistance temperature of about 120 to 160° C., which is insufficient for heat resistance. Therefore, when an internal short circuit occurs, the separator shrinks due to the short circuit reaction heat and short circuits in a larger area, which leads to a thermal runaway state that generates more reaction heat.

[0006] Therefore, in order to maintain the insulation of the battery electrodes to reduce the possibility of a short circuit between the positive electrode and the negative electrode, a method for coating an insulating liquid on a portion of the positive electrode is being devised.

[0007] Figure 1 1 is a schematic diagram of a conventional electrode insulating liquid supply device. As shown in the figure, the insulating liquid is supplied from the storage tank 10 storing the predetermined insulating liquid to the insulating liquid coating die 40 through the supply pipeline 20. The insulating liquid with high viscosity is pumped by the pump 30 so as to be supplied to the coating die 40, and the insulating liquid is discharged from the coating die 40 through the nozzle and then coated on the surface of the positive electrode. When the coating is completed, the insulating liquid of the supply pipeline is returned to the storage tank 10 via the return pipeline 50 through the reversing valve 21.

[0008] However, bubbles are inevitably mixed in the insulating liquid supplied to the supply line of the conventional electrode insulating liquid supply device. It is estimated that the bubbles are generated by the liquid level difference when the insulating liquid is sent to the storage tank 10, or by the pores in the pump 30 installed in the supply line 20, the pores between the supply line 20 and the pump 30, and the leakage.

[0009] If bubbles are generated in the insulating liquid transferred to the supply line, when the insulating layer is applied by the coating die and then thermally dried, pinhole defects in which pinholes are generated at the positions where the bubbles evaporate are generated. The pinhole defects adversely affect the insulating properties of the electrode, making it difficult to achieve the designed electrode insulation performance and increasing the risk of short circuits between electrodes.

[0010] Therefore, a technology is required for suppressing pinhole defects by removing bubbles in the insulating liquid when the insulating liquid is supplied to the electrode.

[0011] In addition, a technique for eliminating bubbles in an electrode slurry when the electrode slurry is applied to a current collector (the electrode slurry is not an insulating liquid) has been proposed. However, the forms of the insulating liquid and the electrode slurry are different because the insulating liquid is a liquid and the electrode slurry is a slurry, and their physical properties (such as viscosity) are also different. Therefore, there is a limitation in applying a defoaming device for the electrode slurry when defoaming the insulating liquid.

[0012] Furthermore, even if the defoaming technology of the electrode slurry is considered to be applied when defoaming the insulating liquid, insufficient defoaming or excessive defoaming may occur if the bubble level in the supply line 20 is not identified. That is, even if the insulating liquid in the storage tank 10 can be mechanically defoamed, it may be difficult to prevent pinholes from being generated in the coating die 40 if the bubble level is not carefully detected.

[0013] Therefore, there is a need for technology to properly identify the bubble level in the supply line and apply this information to the defoaming process.

[0014] [Prior art literature]

[0015] [Patent document]

[0016] Korean Patent No. 10-2035822 Summary of the invention

[0017] Technical issues

[0018] The present application is believed to solve at least some of the above problems.For example, one aspect of the present application provides an electrode insulating liquid supplying apparatus and method for removing bubbles generated when supplying insulating liquid to an electrode.

[0019] Furthermore, another aspect of the present invention provides an electrode insulating liquid supplying apparatus and method for effectively removing bubbles by measuring bubbles generated in a supply line in real time when supplying the insulating liquid to an electrode.

[0020] Technical Solution

[0021] A device for supplying insulating liquid to form an insulating coating on an electrode for solving the above-mentioned problem comprises: a storage tank storing the insulating liquid; a coating die head at which the insulating liquid is coated on the electrode; a supply pipeline connected to the storage tank and supplying the insulating liquid to the coating die head; a pump mounted on the supply pipeline; a defoaming tank connected to the storage tank and supplying defoamed insulating liquid to the storage tank; a vacuum pump eliminating bubbles of the insulating liquid in the defoaming tank by applying vacuum to the defoaming tank; a bubble sensor mounted on the supply pipeline and sensing the generation of bubbles in the supply pipeline in real time; and a controller adjusting the operating conditions of the device based on the amount of bubbles sensed by the bubble sensor.

[0022] In one example, if the amount of bubbles sensed by the bubble sensor is equal to or less than a predetermined value, the controller may control to supply the insulating liquid to the coating die head, and if the amount of bubbles sensed by the bubble sensor exceeds the predetermined value, the controller may control to stop the supply of the insulating liquid to the coating die head.

[0023] Alternatively, the controller may adjust the vacuum degree of the vacuum pump or the number of rotations of a stirring blade installed in the defoaming tank according to the amount of bubbles sensed by the bubble sensor.

[0024] In one example, the apparatus may further include an insulation liquid return line that returns the insulation liquid from the supply line to the defoaming tank through a reversing valve.

[0025] In a preferred example of the present invention, clean dry air (CDA) of a predetermined pressure may be supplied into the defoaming tank, and the insulating liquid in the defoaming tank may be transferred to the storage tank by the pressure of the clean dry air.

[0026] Specifically, under the operating conditions of the defoaming tank and taking into account the viscosity of the insulating liquid, the pressure of the clean dry air can be set within a range in which the clean dry air does not dissolve in the insulating liquid. In one example, the pressure of the clean dry air is in the range of 0.3 to 2 MPa. In a specific example, the clean dry air can be nitrogen.

[0027] Preferably, the bubble sensor is an ultrasonic sensor. In addition, at least one bubble sensor may be installed at a position of the supply line where the frequency of bubble generation is relatively high.

[0028] In addition, the present invention provides a method for supplying an insulating liquid to form an insulating coating on an electrode. In one example, the method for supplying an insulating liquid of the present invention includes: eliminating bubbles of the insulating liquid by applying a vacuum to a defoaming tank in which a predetermined amount of insulating liquid is stored; transferring the defoamed insulating liquid from the defoaming tank to a storage tank; and transferring the insulating liquid in the storage tank to a coating die via a supply line to form an insulating coating on the electrode at the coating die with the defoamed insulating liquid. In particular, the method may further include adjusting the operating conditions of an apparatus for supplying insulating liquid based on the amount of bubbles sensed by the bubble sensor by sensing bubbles in the supply line using a bubble sensor during the transfer of the insulating liquid via the supply line.

[0029] Beneficial Effects

[0030] According to the electrode insulating liquid supplying apparatus and method of the present invention, pinhole defects of the insulating coating can be reduced by suppressing bubbles in the insulating liquid supply line as much as possible.

[0031] In addition, the bubble generation level in the insulating liquid supply line can be monitored in real time by installing a bubble sensor in the supply line, thereby removing bubbles more effectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of a conventional electrode insulating liquid supply device.

[0033] Figure 2 is a schematic diagram of an electrode insulating liquid supply device according to an embodiment of the present invention.

[0034] Figure 3 is a schematic diagram of an ultrasonic sensor used in the electrode insulating liquid supplying device according to the present invention.

[0035] Figure 4 is a schematic diagram of an electrode insulating liquid supply device according to another embodiment of the present invention. DETAILED DESCRIPTION

[0036] Hereinafter, the detailed configuration of the present invention will be described in detail with reference to the accompanying drawings and various embodiments. The embodiments described below are exemplary to assist understanding of the present invention, and in order to facilitate understanding of the present invention, the accompanying drawings are not drawn to scale, and the sizes of some components may be exaggerated.

[0037] Since the concept of the present invention allows various changes and many embodiments, specific embodiments will be shown in the drawings and described in detail herein. However, this is not intended to limit the present invention to the specific form disclosed, and it should be understood to include all changes, equivalents and substitutes included in the spirit and scope of the present invention.

[0038] The present invention provides an apparatus for supplying an insulating liquid to form an insulating coating on an electrode.

[0039] The device for supplying insulating liquid of the present invention comprises: a storage tank, which stores the insulating liquid; a coating die, which coats the insulating liquid on an electrode; a supply pipeline, which is connected to the storage tank and supplies the insulating liquid to the coating die; a pump, which is installed on the supply pipeline; a defoaming tank, which is connected to the storage tank and supplies the defoamed insulating liquid to the storage tank; a vacuum pump, which eliminates bubbles of the insulating liquid in the defoaming tank by applying vacuum to the defoaming tank; a bubble sensor, which is installed on the supply pipeline and senses the generation of bubbles in the supply pipeline in real time; and a controller, which adjusts the operating conditions of the device based on the amount of bubbles sensed by the bubble sensor.

[0040] One feature of the present invention is to allow mutual connection by installing a defoaming tank for performing bubble elimination in an electrode insulating liquid supply device independently from an insulating liquid storage tank. Since a general insulating liquid storage tank has airtightness limitations in structure, it is inefficient to eliminate bubbles by directly connecting a vacuum pump to the insulating liquid storage tank. In addition, a discharge line for exhausting air at the time of defoaming and a line connected to the vacuum pump should be in the tank, and according to the structure of a conventional storage tank, it is difficult to install complicated lines.

[0041] Therefore, in the present invention, a separate defoaming tank having airtightness and being easy to install is installed and connected to the storage tank. In addition, when the defoaming tank and the storage tank are installed separately, the number of tanks capable of storing the insulating liquid becomes two, and accordingly, the insulating liquid storage capacity increases, and the insulating liquid flow rate and capacity of the defoaming tank and the storage tank can be appropriately controlled. In some cases, if a plurality of defoaming tanks are connected to the storage tank, the capacity of the storage tank can be increased.

[0042] (First Embodiment)

[0043] Figure 2 is a schematic diagram of an electrode insulating liquid supplying apparatus 100 according to a first embodiment of the present invention.

[0044] As shown in the figure, the insulating liquid is supplied from the storage tank 110 storing the predetermined insulating liquid to the insulating liquid coating die 140 through the supply line 120. The insulating liquid is composed of about 90% or more of a binder and 10% or less of a solid, and has a relatively high viscosity (900 to 5,000 cP). When the viscosity is low, the fluidity increases. Therefore, it is preferable to reduce the viscosity of the insulating liquid as much as possible. The viscosity of the insulating liquid is preferably in the range of 900 to 3000 cP. The insulating liquid filled in the storage tank 110 is preferably an insulating liquid that has been defoamed in advance from the defoaming tank 160, as will be described later. The stirring blade 112 for stirring the insulating liquid is rotated in the storage tank 110 by the motor 111.

[0045] The predetermined insulating liquid that can be used in the present invention may be a solution containing a polymer made of one or more selected from the group consisting of polybutadiene, polyurethane, polyimide, acetate, polyester, polyphenylene sulfide, polypropylene, styrene-butadiene-based copolymers, (meta)acrylic acid, (meta)acrylate copolymers, polyacrylonitrile, polyvinyl chloride, polyfluorinated compounds, polyvinyl alcohol, and polycyanoacrylate; or the predetermined insulating liquid may be a solution containing a monomer used for polymerization of a polymer selected from one or more selected from the group consisting of polybutadiene, polyurethane, polyimide, acetate, polyester, polyphenylene sulfide, polypropylene, styrene-butadiene-based copolymers, (meta)acrylic acid, (meta)acrylate copolymers, polyacrylonitrile, polyvinyl chloride, polyfluorinated compounds, polyvinyl alcohol, and polycyanoacrylate.

[0046] Specifically, a polyvinylidene fluoride (PVdF)-based insulating liquid, a ceramic-based insulating liquid (eg, an aluminum hydroxide-based insulating liquid such as boehmite) may be used.

[0047] The insulating liquid may include one or more solvents selected from the group consisting of water, glycerol, ethylene glycol, propylene glycol, dimethyl sulfoxide, dimethylformamide, acetonitrile, ethylene carbonate, furfuryl alcohol, and methanol.

[0048] The high viscosity insulating liquid of the storage tank 110 is pumped by the pump 130 to be supplied to the coating die 140, and the insulating liquid is discharged from the coating die 140 by a predetermined nozzle so as to be coated on the surface of the electrode (e.g., the positive electrode). The pump 130 may be, for example, a Mono pump having a simple structure. The Mono pump is composed of a stator and a spiral rotor, the stator being formed of an elastomer and having a spiral channel in the pump, and the spiral rotor rotating in the stator. Here, if the rotor rotates in the stator, the liquid continuously flows from the inlet to the discharge port in the pump in the axial direction. In this specification, a Mono pump is mentioned, but any pump that can appropriately convey the liquid in the supply line may be used in consideration of the viscosity and physical properties of the insulating liquid.

[0049] In the present embodiment, the defoaming tank 160 is connected to the insulating liquid storage tank 110 through a pipe 170. The insulating liquid storage capacity of the defoaming tank 160 may be the same as or different from that of the insulating liquid storage tank 110, but it is preferable to make them the same in terms of capacity management. As in the storage tank 110, in the defoaming tank 160, the insulating liquid may be stirred by rotating the stirring blade 162 by the motor 161. The number of revolutions of the stirring blade 162 may be selected within an appropriate range so that bubbles in the insulating liquid are raised in addition to the stirring of the insulating liquid. Reference numeral 163 denotes a pressure gauge, and reference numeral 164 denotes a discharge line, through which air mixed with bubbles may be discharged. After the bubbles are eliminated by the vacuum pump 180, the insulating liquid in the defoaming tank 160 is supplied to the storage tank 110 through the pipe 170, as will be described below.

[0050] The defoaming tank 160 is connected to the vacuum pump 180 through a connecting line 181 , and the air in the defoaming tank 160 may be exhausted through a discharge line 164 by vacuum force.

[0051] The vacuum degree of the vacuum pump 180 may be appropriately adjusted according to the capacities of the defoaming tank 160 and the storage tank 110 and the amount of bubbles generated in each tank and the air flow rate.

[0052] Air (air in which bubbles may also be mixed) inevitably injected into the vacuum pump 180 by vacuum suction of the vacuum pump 180 is discharged to the outside via a discharge line 184 provided in the vacuum pump 180 .

[0053] Figure 2 An example is shown in which a reversing valve 121 is installed in the supply line 120 adjacent to the coating die 140, and an insulating liquid return line 150 is installed from the reversing valve 121 to the defoaming tank 160. This is an insulating liquid circulation loop (closed loop) formed by the defoaming tank 160-insulating liquid storage tank 110-supply line 120-(coating die 140)-reversing valve 121-return line 150.

[0054] The reversing valve 121 may be, for example, a three-way valve, and adjusts the supply of insulating liquid from the supply line 120 to the coating die 140, and the flow of insulating liquid from the supply line 120 to the return line 150 (when coating is terminated or stopped).

[0055] The insulating liquid pipelines such as the supply pipeline 120 and the return pipeline 150 are preferably formed as pipelines made of a material having a small friction force with the insulating liquid. In particular, since the insulating liquid has a large viscosity, it may be difficult to obtain a desired conveying speed when conveying to the coating machine according to the friction force with the pipeline. In addition, the diameter of the pipeline is preferably a value suitable for conveying high-viscosity insulating liquid. Therefore, the material, diameter, etc. of the pipeline can be appropriately determined in consideration of the viscosity and conveying speed of the insulating liquid. For example, if the viscosity of the insulating liquid is in the range of 900 to 5000 cP, the insulating liquid can be supplied to the coating machine at a conveying speed of 0.060 to 0.30 L / min. In this case, for example, a pipeline of 1 inch or more can be used. In addition, a pipeline made of stainless steel or Teflon having a low friction force with the high-viscosity insulating liquid can be used as the pipeline.

[0056] In addition, it is preferable to set the pump pressure of the Mono pump to an appropriate value so as to achieve a target delivery speed of the high-viscosity insulating liquid.

[0057] The advantage of the circulation loop is that the remaining insulating liquid can be defoamed and reused in the insulating coating. Here, in the insulating liquid return line 150, if a predetermined valve and a branch line (not shown) connected to the discharge line are installed before reaching the defoaming tank 160, the discharge of the insulating liquid and the return to the defoaming tank 160 can be selectively or simultaneously achieved as needed.

[0058] Since this valve configuration is also assembled in a general insulating liquid supply device, a detailed description of the function and effect will be omitted here.

[0059] Reference Figure 2 , other valves capable of adjusting the flow rate are installed at the connecting pipelines, pipes, etc. of each element. Here, the main points about these valves correspond to the general technical matters of the pipelines, so their detailed description will be omitted here.

[0060] The main feature of the present invention is that the bubble measurement and the bubble elimination are organically linked by installing a bubble sensor 190 capable of sensing the generation state of bubbles in real time in the insulating liquid supply line 120 .

[0061] By operating the defoaming system composed of the vacuum pump 180 and the defoaming tank 160 by the controller C to transfer the defoamed insulating liquid to the storage tank 110, or defoaming the insulating liquid returned to the defoaming tank 160 and transferring the defoamed insulating liquid to the storage tank 110, the insulating liquid can be effectively reused and the bubble level of the insulating liquid in the supply line 120 can be maintained constant. However, if the bubble level in the supply line 120 is not identified, the bubbles may not be sufficiently eliminated or the defoaming may be excessive.

[0062] Therefore, in the present invention, the bubble generation state is monitored in real time by installing a bubble sensor 190 in the supply line 120. In the present invention, as a specific example of the bubble sensor 190, an ultrasonic sensor is applied to effectively measure the amount of bubbles in the supply line, as will be described later.

[0063] Specifically, in the initial period of operation of the insulating liquid supplying apparatus 100, the insulating liquid that has been defoamed in advance in the defoaming tank 160 is transferred to the storage tank 110, and thus pinhole defects can be prevented in the coating die 140. However, thereafter, during the process of repeatedly and continuously coating the insulating liquid, bubbles may be generated by the liquid level drop in the storage tank 110, and bubbles may be generated in the supply line 120 due to the continuous inflow of impurity-containing air from the outside during the pumping process of the pump 120. The bubble sensor 190 may sense the amount of bubbles in real time and transmit the data to the controller C of the insulating liquid supplying apparatus 100. The controller C may adjust the operating conditions of the insulating liquid supplying apparatus 100 based on the data on the amount of bubbles. In this specification, the "operating condition" of the insulating liquid supply device includes a decision on whether to continue to supply the insulating liquid to the supply line (i.e., a decision on the open / closed state of each valve), a temperature or pressure setting condition in the defoaming tank, an operating condition such as the number of revolutions of the stirring blade, and a condition value related to the operation of each component, such as the vacuum degree of the vacuum pump, and this "operating condition" is a concept including the overall device operating conditions for adjusting the defoaming performance or whether to continue to supply the insulating liquid according to these conditions. Likewise, according to the present invention, the operation of the insulating liquid supply device 100 is organically adjusted based on the value of the bubble amount measured by the bubble sensor, and the pinhole generation of the insulating coating can be effectively suppressed.

[0064] Specifically, data on a predetermined range of bubble amounts at which pinhole defects occur may be set in advance, and the operating conditions of the device may be adjusted by comparing the data with the bubble amount measured by the bubble sensor. If the bubble amount sensed by the bubble sensor is equal to or less than a predetermined value, the insulating liquid continues to be supplied to the coating die, but if the bubble amount sensed by the bubble sensor exceeds a predetermined value, the controller C may block the reversing valve 121 and stop the supply of the insulating liquid. In this case, the insulating liquid containing bubbles exceeding the predetermined value is returned to the defoaming tank 160 via the return line 150 and undergoes a defoaming process. After defoaming, the insulating liquid is again supplied to the supply line 120 via the storage tank 110, the bubble amount is measured again by the bubble sensor 190, and this process may be repeated until the bubble amount is reduced to or less than a predetermined value. That is, according to the present invention, pinhole defects may be suppressed by delivering an insulating liquid having bubbles equal to or less than a predetermined amount to the coating die.

[0065] In addition, even if the amount of bubbles sensed by the bubble sensor 190 exceeds a predetermined value or if the amount of bubbles tends to increase even when the amount of bubbles is within a predetermined value, the defoaming performance can be enhanced by increasing the vacuum degree (the vacuum degree is one of the operating conditions of the device) of the vacuum pump 180. Alternatively, the air discharge in the defoaming tank 160 can be enhanced by increasing the number of revolutions of the stirring member 162 installed in the defoaming tank 160.

[0066] In summary, according to the present invention, the defoaming degree of the insulating liquid can be controlled in real time by monitoring the amount of bubbles in the supply line in real time and adjusting the operating conditions of the insulating liquid supply device 100 in response to the operating conditions and various variables of the device based on the detected data.

[0067] (Second Embodiment)

[0068] Reference Figure 2 , a second embodiment of the present invention will also be described.

[0069] In this embodiment, clean dry air (CDA) is supplied through a supply line 165 of CDA so as to transfer the insulating liquid in the defoaming tank 160 to the storage tank 110. Here, as in the pump 130 installed in the supply line 120 of the insulating liquid supplying apparatus 100, the insulating liquid defoamed in the defoaming tank 160 may be transferred to the storage tank 110 by installing a separate pump in the pipe 170 connecting the defoaming tank 160 to the storage tank 110. However, considering that one of the main causes of bubble generation is considered to be pores and leakage, transfer by a pump has the risk of possible mixing of bubbles. Therefore, in this embodiment, the insulating liquid is transferred by applying pressure with CDA instead of by a pump. The clean dry air system is a system that provides optimal compressed air by filtering contaminants such as dust, oil, and moisture to below a predetermined level as required.

[0070] In the present invention, the defoamed insulating liquid in the defoaming tank 160 can be effectively transferred to the storage tank 110 by using compressed air (CDA) of a clean dry air system. Strictly speaking, the insulating liquid in the defoaming tank 160 is transferred to the storage tank 110 by the force generated by the pressure of the CDA and the potential energy formed by the liquid level difference in the defoaming tank 160.

[0071] exist Figure 2 In FIG. 1 , R represents a regulator that allows CDA to be delivered at a constant pressure.

[0072] Since the insulating liquid has a high viscosity as described above, if the pressure of CDA is appropriately set, the generation of bubbles due to the dissolution of CDA in the insulating liquid can be prevented. That is, under the operating conditions of the defoaming tank (e.g., the temperature and pressure in the defoaming tank) and in consideration of the viscosity of the insulating liquid, it is important to set the pressure of the clean dry air (CDA) in a range in which the clean dry air does not dissolve. Under the operating conditions of the defoaming tank used, when considering an insulating liquid with a viscosity in the range of 900 to 5000 cP, if the pressure of CDA is set to 2 MPa, CDA is rarely dissolved in the insulating liquid. In order to convey the insulating liquid, a pressure of at least 0.3 MPa is necessary. The pressure is preferably equal to or less than 1 MPa, and more preferably in the range of 0.5 to 0.7 MPa.

[0073] Alternatively, if nitrogen is used as CDA, dissolution in the insulating liquid can be more effectively prevented. N2 is suitable as the CDA pressure medium because it has low chemical activity and low solubility in water at low pressure. Likewise, in the present invention, using CDA to transport the insulating liquid has the following advantages: the insulating liquid can be properly transported while avoiding the risk of bubbles generated by the pump.

[0074] (Third Embodiment)

[0075] Figure 3 1 is a schematic diagram of an ultrasonic sensor 190 used in the electrode insulating liquid supplying device 100 of the present invention. That is, in this embodiment, an ultrasonic sensor is used as the bubble sensor 190.

[0076] like Figure 3 As shown, the ultrasonic sensor 190 of this example is composed of a transmitting sensor 190A (piezoelectric sensor) installed on one side of the pipe of the supply line 120 and a receiving sensor 190B (piezoelectric sensor) installed on the other side of the pipe, and has a structure that senses the bubble generation state by the intensity of the ultrasonic wave emitted from the transmitting sensor 190A. That is, if the ultrasonic wave is generated by applying a voltage to the transmitting sensor 190A, the ultrasonic wave passes through the pipe and is sensed by the receiving sensor 190B. When there is no or only a little bubble (see Figure 3 ), the intensity of the ultrasonic wave sensed by the receiving sensor 190B increases, which is detected as a larger voltage in the receiving sensor 190B. Figure 3 ), the intensity of the ultrasonic wave decreases, which is detected as a smaller voltage in the receiving sensor 190B.

[0077] Likewise, in the apparatus of the third embodiment, the number or amount of bubbles generated in the insulating liquid in the supply line 120 can be sensed and detected in real time by the ultrasonic sensor composed of the two sensors 190A and 190B.

[0078] In the above example, the ultrasonic sensor is composed of two sensors, but the number of transmitting and receiving sensors is not particularly limited, and two or more sensors may be applied as long as each of these sensors can effectively measure the number of bubbles in the tube of the supply line 120. By using the ultrasonic sensor, the number of bubbles can be effectively measured in a non-contact manner. Therefore, the ultrasonic sensor is preferable to other kinds of sensors in terms of avoiding contamination of the insulating liquid.

[0079] (Fourth Embodiment)

[0080] Figure 4 is a schematic diagram of an electrode insulating liquid supplying device 100 according to another embodiment of the present invention.

[0081] In this embodiment, a plurality of ultrasonic sensors are installed at locations in the supply line where the frequency of bubble generation is high.

[0082] That is, since bubbles are considered to be generated by a liquid level drop when pouring the insulating liquid in the storage tank 110 or by pores and leakage when passing through the pump, ultrasonic sensors 190 and 190' are respectively installed in the supply line 120 between the lower portion of the storage tank 110 and the pump 130 and in the supply line 120 after the pump 130 according to the number of locations where bubbles are generated.

[0083] In this way, by clearly identifying the number of locations where bubbles are generated in the insulating fluid and monitoring the bubble generation situation in each location, the bubble generation situation and mechanism in the supply pipeline can be effectively identified and a database can be established based on this to avoid pinhole defects.

[0084] [Example]

[0085] Based on each of the above embodiments, the defoaming performance of the electrode insulating liquid supply device of the present invention is compared with that of the conventional electrode insulating liquid supply device in combination with the large-scale production of electrodes.

[0086] The PVdF insulating liquid was obtained by dissolving 7% of PVdF solid in NMP solvent, and 200L of the PVdF insulating liquid was poured into a storage tank in the same manner as in scale production, and 200L of the PVdF insulating liquid was also poured into a defoaming tank, and then defoamed for 12 hours at a vacuum level of 0.35MPa of a vacuum pump. The viscosity of the PVdF insulating liquid is in the range of 2,000 to 3,000cP. In this embodiment, the amount of insulating liquid is set to 200L, but the amount of insulating liquid can be selected in the range of 100 to 200L according to production conditions. In some cases, a larger amount of insulating liquid can be selected.

[0087] In the comparative example, 200 L of the same PVdF insulating liquid as that of the embodiment was poured into the storage tank of a conventional electrode insulating liquid supplying apparatus which was not equipped with a defoaming tank, allowed to stand for 12 hours, and the bubble generation state was examined.

[0088] As a result of measuring the number of bubbles in a specific portion of the supply line after the pumping process by an ultrasonic sensor after 12 hours, 150 bubbles were generated in the case of the comparative example, while the number of bubbles was reduced by 96% in the case of the embodiment of the present invention.

[0089] As described above, the present invention relates to an insulating liquid supplying apparatus capable of monitoring the generation of bubbles in real time and effectively eliminating the bubbles according to the bubble generation state.

[0090] Furthermore, the present invention may be understood as a method for supplying an insulating liquid to form an insulating coating on an electrode.

[0091] The method for supplying an insulating liquid of the present invention comprises: eliminating bubbles of the insulating liquid by applying vacuum to a defoaming tank in which a predetermined amount of the insulating liquid is stored; transferring the defoamed insulating liquid from the defoaming tank to a storage tank; transferring the insulating liquid in the storage tank to a coating die via a supply pipeline to form an insulating coating on an electrode at the coating die with the defoamed insulating liquid; and during the transfer of the insulating liquid via the supply pipeline, adjusting the operating conditions of an apparatus for supplying the insulating liquid based on the amount of bubbles sensed by the bubble sensor by sensing bubbles in the supply pipeline using the bubble sensor.

[0092] According to the insulating liquid supply method of the present invention, the generation of bubbles can be suppressed while the state of bubble generation is monitored in real time, thereby more effectively improving the quality of the insulating coating.

[0093] In the above, the present invention has been described in more detail by the drawings and examples. Therefore, the embodiments described in the specification and the configurations depicted in the drawings are only the most preferred embodiments of the present invention, and do not represent the entire technical concept of the present invention. It should be understood that various equivalents and variations may be substituted for them when submitting this application.

[0094] [Explanation of Reference Numerals]

[0095] 100: Insulating fluid supply equipment

[0096] 10, 110: (insulating liquid) storage tank

[0097] 20, 120: Supply pipeline

[0098] 21, 121: Directional valve

[0099] 30, 130: Pump

[0100] 40, 140: coating die head

[0101] 50, 150: Insulation liquid return pipeline

[0102] 160: Defoaming tank

[0103] 161: Stirring motor

[0104] 162: stirring blade

[0105] 163: Pressure gauge

[0106] 164: Discharge line

[0107] 165: CDA supply pipeline

[0108] 170: Pipeline

[0109] 180: Vacuum pump

[0110] 181: Connecting pipeline

[0111] 184: Discharge line

[0112] 190, 190': Bubble sensor (ultrasonic sensor)

[0113] 190A: Transmitter sensor

[0114] 190B: Receiving sensor

[0115] C: Controller

Claims

1. An apparatus for supplying an insulating liquid to form an insulating coating on an electrode, the apparatus comprising: a storage tank, wherein the storage tank stores the insulating liquid; A coating die head, where the insulating liquid is coated on the electrode; a supply line connecting the storage tank to the coating die and supplying the insulating liquid to the coating die; a pump installed on the supply line; an airtight defoaming tank connected to the storage tank through a pipeline and supplying defoamed insulating liquid to the storage tank, the defoaming tank also being connected to a vacuum pump through a connecting line and connected to a discharge line to discharge gas from the defoaming tank, wherein a predetermined stirring member is installed in the defoaming tank, the stirring member including a stirring blade; a vacuum pump, wherein the vacuum pump eliminates bubbles of the insulating liquid in the defoaming tank by applying a vacuum to the defoaming tank; at least one bubble sensor installed on the supply line and sensing the generation of bubbles in the supply line in real time; and A controller, the controller being used to: If the amount of bubbles sensed by the bubble sensor is equal to or less than a predetermined value, supplying the insulating liquid to the coating die head, or If the amount of bubbles sensed by the bubble sensor exceeds the predetermined value, the supply of the insulating liquid to the coating die head is stopped, or adjusting the vacuum level of the vacuum pump according to the amount of bubbles sensed by the bubble sensor, or The number of rotations of a stirring blade installed in the defoaming tank is adjusted according to the amount of bubbles sensed by the bubble sensor.

2. The apparatus according to claim 1, further comprising an insulating liquid return line for returning the insulating liquid from the supply line to the defoaming tank through a reversing valve. 3 . The apparatus of claim 1 , wherein clean dry air (CDA) of a predetermined pressure is supplied into the defoaming tank, and the insulating liquid in the defoaming tank is transferred to the storage tank by the pressure of the clean dry air.

4. The device as claimed in claim 3, wherein: Under the operating conditions of the defoaming tank and in consideration of the viscosity of the insulating liquid, the pressure of the clean dry air is set within a range in which the clean dry air does not dissolve in the insulating liquid.

5. The apparatus of claim 4, wherein the pressure of the clean dry air is in the range of 0.3 to 2 MPa.

6. The apparatus of claim 3, wherein the clean dry air is nitrogen.

7. The apparatus of claim 1, wherein the bubble sensor is an ultrasonic sensor.

8. The apparatus of claim 1, wherein at least one bubble sensor is installed at a position of the supply line where a frequency of bubble generation is high.

9. The apparatus of claim 7, wherein the bubble sensor is installed at least one of: a position on the supply line between the reservoir and the pump, and a position on the supply line between the pump and a reversing valve.

10. The apparatus of claim 1, wherein the viscosity of the insulating liquid is in the range of 900 to 5000 cP.

11. A method for supplying an insulating liquid to form an insulating coating on an electrode using the apparatus according to any one of claims 1 to 10, the method comprising: eliminating bubbles of the insulating liquid by applying vacuum to a defoaming tank storing a predetermined amount of the insulating liquid therein, the defoaming tank having a predetermined stirring member including a stirring blade; conveying the defoamed insulating liquid from the defoaming tank to a storage tank through a pipeline; transferring the insulating liquid in the storage tank to a coating die via a supply line to form an insulating coating on an electrode at the coating die with the defoamed insulating liquid, wherein the insulating liquid in the storage tank is pumped by a pump to be provided to the coating die; and sensing bubbles in the supply line using at least one bubble sensor during conveying of the insulating liquid via the supply line, The controller is used to: If the amount of bubbles sensed by the bubble sensor is equal to or less than a predetermined value, supplying the insulating liquid to the coating die head, or If the amount of bubbles sensed by the bubble sensor exceeds the predetermined value, the supply of the insulating liquid to the coating die head is stopped, or adjusting the vacuum level of the vacuum pump according to the amount of bubbles sensed by the bubble sensor, or The number of rotations of a stirring blade installed in the defoaming tank is adjusted according to the amount of bubbles sensed by the bubble sensor. 12 . The method of claim 11 , wherein the insulating liquid in the defoaming tank is transferred to the storage tank by a predetermined pressure of clean dry air (CDA) supplied to the defoaming tank.

13. The method of claim 11, wherein at least one bubble sensor is installed at a position of the supply line where a frequency of bubble generation is high.

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