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CN-116529900-B - Double slit die for simultaneous electrode slurry coating and insulating solution coating and coating method using the same

CN116529900BCN 116529900 BCN116529900 BCN 116529900BCN-116529900-B

Abstract

The present invention relates to a double slit die and a coating method using the same, in which there are advantages in that electrode paste coating and insulating solution coating are simultaneously performed through the double slit die to prevent electrode paste sliding from occurring at edges of the electrode paste layer, and in that the electrode paste layer and the insulating layer can be formed on a current collector sheet in a multi-line manner by including a gasket (shim) having a structure in which a plurality of discharge lines capable of discharging the electrode paste or the insulating solution in a multi-line manner are formed, thereby increasing process efficiency.

Inventors

  • Li Douxuan
  • Sun Zaijiong
  • An Changfan

Assignees

  • 株式会社LG新能源

Dates

Publication Date
20260512
Application Date
20220726
Priority Date
20211129

Claims (9)

  1. 1. A dual slit die comprising a lower block, a middle block, and an upper block, the dual slit die comprising: a lower pad located between the lower block and the middle block; An upper pad located between the middle block and the upper block; a lower manifold formed in the lower block to store electrode paste, and An upper manifold formed in the upper block to store an insulating solution, Wherein the double slit die has a structure in which the electrode paste stored in the lower manifold is branched and discharged in n rows by an electrode paste discharge line formed in the lower gasket, and the insulating solution stored in the upper manifold is branched and discharged in 2n rows by an insulating solution discharge line formed in the upper gasket, and N is an integer of 1 or more, Wherein the width of an electrode paste discharging portion and the width of an insulating solution discharging portion overlap each other in a vertical direction of a cross section of the upper gasket, the electrode paste discharging portion being an opening portion of the electrode paste discharging line, the insulating solution discharging portion being an opening portion of the insulating solution discharging line, and The overlapping range is in the range of 5% to 30% of the width of the insulation solution discharge portion.
  2. 2. The dual slit die of claim 1, wherein a first plane in which the upper shim extends intersects a second plane in which the lower shim extends at an angle in the range of 20 ° to 60 °.
  3. 3. The dual slit die of claim 1, wherein in a direction in which said electrode slurry and said insulating solution are applied to a current collector sheet, An electrode paste discharging portion is located upstream, the electrode paste discharging portion being an opening portion of the electrode paste discharging line, An insulating solution discharging portion is located downstream, the insulating solution discharging portion being an opening portion of the insulating solution discharging line, Further comprising a UV lamp downstream of the insulation solution discharge portion.
  4. 4. A coating method for applying an electrode slurry and an insulating solution to a current collector sheet by a double-slit die comprising a lower block, an intermediate block, and an upper block, the method comprising: Forming an electrode paste layer on the collector sheet by branching and discharging the electrode paste stored in a lower manifold formed in the lower block into n rows by an electrode paste discharge line formed in a lower gasket located between the lower block and the middle block, and Forming an insulating layer on the current collector sheet by branching and discharging the insulating solution stored in an upper manifold formed in the upper block into 2n rows by an insulating solution discharge line formed in an upper spacer between the middle block and the upper block; n is an integer of 1 or more, Wherein the method comprises the steps of The electrode slurry layer and the insulating layer formed on the collector sheet are applied so as to overlap each other, and The overlapping range is 5% to 30% of the width of the insulating layer formed in the vertical direction of the collector sheet.
  5. 5. The method of claim 4, wherein The temperature (T 1 ) of the insulating solution discharged by the insulating solution discharge line is in the range of 22 ℃ to 27 ℃, and The temperature (T 2 ) of the electrode paste discharged by the electrode paste discharge line is in the range of 20 to 25 ℃, Wherein the temperature (T 1 ) of the insulating solution is higher than the temperature (T 2 ) of the electrode paste, and the difference (T 1 - T 2 ) between the temperature (T 1 ) of the insulating solution and the temperature (T 2 ) of the electrode paste is in the range of 1 ℃ to 4 ℃.
  6. 6. The method of claim 4, further comprising drying the electrode paste applied on the current collector sheet after forming the insulating layer.
  7. 7. The method of claim 4, further comprising mixing a UV polymerization initiator with the insulating solution prior to forming the insulating layer.
  8. 8. The process of claim 7 wherein the UV polymerization initiator is one or more of 2-hydroxy-2-methylbenzophenone (HMPP), 1-hydroxy-cyclohexylphenyl-one, benzophenone, 2-hydroxy-1- [4- (2-hydroxyethoxy) phenyl ] -2-methyl-1-propanone, 2- [ 2-oxo-2-phenyl-acetoxy-ethoxy ] -ethyl ester of oxy-phenylacetic acid, 2- [ 2-hydroxyethoxy ] -ethyl ester of oxy-phenyl-acetic acid, alpha-dimethoxy-alpha-phenylacetophenone, 2-benzyl-2- (dimethylamino) -1- [4- (4-morpholinyl) phenyl ] -1-butanone, 2-methyl-1- [4- (methylthio) phenyl ] -2- (4-morpholinyl) -1-propanone, diphenyl (2, 4, 6-trimethylbenzoyl) -phosphine oxide, bis (2, 4, 6-trimethylbenzoyl) -phenylphosphine oxide, bis (. Eta.5-2, 4-cyclopentadien-1-yl), bis [2, 6-difluoro-3- (4-morpholinyl) phenyl ] -1-butanone, 2-methyl-1- [4- (4-morpholinyl) phenyl ] -2- (4-morpholinyl) phenyl) i-butanone, diphenyl-phosphine oxide, bis (eta 5, 4-cyclopentadienyl-1-yl) bis [2, 6-difluoro-3- (1-hydroxy-1-benzoyl) phenyl ] iodonium phosphate And methylbenzoyl formate.
  9. 9. The method according to claim 7, further comprising the step of curing the insulating solution containing the UV polymerization initiator by irradiating the insulating solution containing the UV polymerization initiator applied on the current collector sheet with UV light after forming the insulating layer.

Description

Double slit die for simultaneous electrode slurry coating and insulating solution coating and coating method using the same Technical Field The present application claims priority based on korean patent application No. 10-2021-0167169 at 29 of 11 of 2021 and korean patent application No. 10-2022-0090580 at 21 of 7 of 2022, all of the disclosures of which are incorporated herein by reference. The present invention relates to a double slit die for simultaneously performing electrode slurry coating and insulating solution coating and a coating method using the same. Background As technology advances and demand for mobile devices increases, demand for secondary batteries also increases rapidly. Among secondary batteries, lithium secondary batteries have been widely used as energy sources for various electronic products and various mobile devices because they have high energy density and operating voltage and have excellent storage and life characteristics. Typically, there is a high demand for prismatic batteries and pouch-shaped batteries, which have a thin thickness in terms of battery shape and can be applied to products such as mobile phones, and there is also a high demand for lithium secondary batteries (such as lithium cobalt polymer batteries) having excellent energy density, discharge voltage, and material-based safety. One of the main research tasks for such secondary batteries is to improve safety. One of the main causes of safety-related accidents in batteries is the attainment of abnormally high temperature conditions due to short circuits between the positive and negative electrodes. That is, in a normal case, a separator is positioned between a positive electrode and a negative electrode to maintain electrical insulation, but in an abnormal operation case, such as in the case of overcharge or overdischarge of the battery, an internal short circuit occurs due to dendrite growth (DENDRITIC GROWTH) of an electrode material or foreign matter, or when a sharp object, such as a nail and a screw, penetrates the battery, the battery is deformed by an external force, and the existing separate separator exhibits its limitations. In general, a microporous film made of a polyolefin resin is generally used as a separator, but the heat resistance temperature is about 120 to 160 ℃, and thus the heat resistance is insufficient. Therefore, when an internal short circuit occurs, there is a problem in that the separator contracts due to the short circuit reaction heat, bringing the positive and negative electrode plates into contact with each other, resulting in a thermal runaway (thermal runaway) state in which a short circuit portion inside the battery is amplified and a larger amount of reaction heat is generated. Generally, a prismatic secondary battery is manufactured by cutting positive and negative electrodes to a predetermined size and overlapping several pieces of positive and negative electrodes. At this time, the edges of the positive electrode or the negative electrode coated with the polymer electrolyte have inconspicuous very small needle-like sharp portions, and the stacking of the electrodes may cause a fine internal short circuit in the portions and adversely affect the battery performance. In particular, even when the edge is coated with the polymer electrolyte, since there are more irregular surfaces in the edge than in the inside, it cannot be uniformly coated, and thus there is a high possibility of short circuit. In addition, when the electrodes of the lower layer and the upper layer are stacked even when the deviation is small, a short circuit may occur between the positive electrode and the negative electrode. Thus, various methods have been studied to reduce the possibility of deformation of the battery or external impact or physical short circuit between the positive and negative electrodes, and for example, one method attaches an insulating tape of a predetermined size on the electrode tab adjacent to the top of the current collector to prevent the electrode tab from contacting the upper end of the electrode assembly and causing short circuit by moving the electrode assembly when the battery is completed. However, the winding operation of such an insulating tape is very complicated, and when the insulating tape is wound to a length extending slightly downward from the top of the current collector, the portion may cause an increase in thickness of the electrode assembly. Generally, as the method of attaching an insulating tape on the electrode tab described above, a method has been adopted in which an electrode paste is coated on a positive electrode and an insulating solution is coated in a region where the electrode paste is not coated (i.e., an uncoated region). On the other hand, as a method of uniformly coating an electrode active material slurry on a collector sheet, a slot die coating process is generally performed. Further, a slot die coating process is performed to coat an electro