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CN-122025549-A - Mylar film, preparation method thereof and lithium battery pole group

CN122025549ACN 122025549 ACN122025549 ACN 122025549ACN-122025549-A

Abstract

The invention provides a Mylar film, a preparation method thereof and a lithium battery pole group, wherein the Mylar film comprises a polyester base film and a functional layer arranged on at least one side surface of the polyester base film, wherein a reticulate pattern array with gradient arrangement density is arranged on one side surface of the functional layer far away from the polyester base film, and adjacent reticulate patterns are communicated with each other to form a capillary liquid guide channel. The preparation method comprises the steps of (1) preparing a lyophile coating slurry, (2) pretreating at least one side surface of a polyester base film, (3) coating the lyophile coating slurry on the surface of the pretreated polyester base film, drying to form a functional layer, and (4) pressing an reticulate pattern array with gradient arrangement density on the surface of the functional layer to obtain the Mylar film. The Mylar film provided by the invention can not only improve the electrolyte infiltration performance and solve the problem of uneven infiltration, but also ensure the insulation strength, avoid the risk of chip falling and short circuit, and simultaneously ensure simple process and controllable cost.

Inventors

  • JIANG YUN
  • ZHANG HAILIN
  • DONG ZHU

Assignees

  • 阿特斯储能科技有限公司

Dates

Publication Date
20260512
Application Date
20260414

Claims (15)

  1. 1. The Mylar film is characterized by comprising a polyester base film and a functional layer arranged on at least one side surface of the polyester base film; the functional layer is provided with reticulate patterns array which are distributed in a gradient way on the surface of one side far away from the polyester base film, and adjacent reticulate patterns are communicated with each other to form a capillary liquid guide channel; The depth of the reticulation is smaller than the thickness of the functional layer, and the reticulation array has lyophilic property.
  2. 2. The mylar film of claim 1, wherein the reticulated array is a non-penetrating porous structure with a porosity of 15% -40%; and/or the contact angle of electrolyte of the reticulate pattern array is less than or equal to 30 degrees.
  3. 3. The mylar film of claim 1 or 2, wherein the functional layer is prepared from raw materials including ceramic particles and a polar binder; Wherein the ceramic particles are made of at least one of alumina, silica or boehmite; and/or the particle size of the ceramic particles is 50-500 nm; And/or the polar binder comprises at least one of polyvinylidene fluoride, polyamide or polyurethane.
  4. 4. The mylar film of claim 1 or 2, wherein the gradient arrangement order of the moire array is greater than or equal to 2 and the bottom moire array density is greater than the top moire array density.
  5. 5. The mylar film of claim 4, wherein the gradient arrangement of the textured array has a progression of 2, comprising a bottom textured array and a top textured array; Wherein the bottom reticulate pattern array density is 1.2-2 times the top reticulate pattern array density.
  6. 6. The mylar film of claim 4, wherein the gradient arrangement of the reticulate array is 3, including a bottom reticulate array, a middle reticulate array, and a top reticulate array; the bottom reticulate pattern array density is 1.2-1.5 times that of the middle reticulate pattern array density, and the bottom reticulate pattern array density is 1.5-2 times that of the top reticulate pattern array.
  7. 7. The mylar film of claim 1 or 2, wherein the cross-hatch shape of the cross-hatch array comprises at least one of diamond, bar, or spiral; and/or the reticulate depth of the reticulate array is 1-5 mu m, and the reticulate width is 2-8 mu m.
  8. 8. The mylar film according to claim 1 or 2, wherein the functional layer has a thickness of 1-10 μm; And/or the thickness of the polyester base film is 10-25 mu m.
  9. 9. A method for preparing a maillard as claimed in any one of claims 1 to 8, wherein the method comprises the steps of: (1) Preparing a lyophile coating slurry; (2) Pretreating at least one side surface of a polyester base film; (3) Coating the lyophile coating slurry on the surface of the pretreated polyester base film, and drying to form a functional layer; (4) Pressing a reticulate pattern array with gradient density arrangement on the surface of the functional layer to prepare the Mylar film; wherein, the step (1) and the step (2) are not in sequence.
  10. 10. The preparation method of the Mylar film according to claim 9, wherein the preparation method of the lyophile coating slurry in the step (1) comprises mixing ceramic particles, a polar binder and a solvent, stirring uniformly, grinding and filtering to obtain the lyophile coating slurry; wherein the mixing mass ratio of the ceramic particles to the polar binder to the solvent is (30-50): (10-20): (30-60); and/or the solvent comprises N-methyl pyrrolidone and/or acetone; And/or the particle size of the lyophile coating slurry is 100-500 nm.
  11. 11. The method for preparing a maillard film of claim 9 wherein the means of pretreatment in step (2) comprises a plasma modification treatment; Wherein the power of the plasma modification treatment is 100-300W; and/or the plasma modification treatment time is 10-30 s; And/or the atmosphere of the plasma modification treatment comprises air or oxygen.
  12. 12. The method of preparing a maillard film of claim 9 wherein the means of coating in step (3) comprises blade coating or slot coating; And/or, the coating thickness of the lyophile coating slurry in the step (3) is 1-10 mu m; And/or, the temperature of the drying in the step (3) is 80-120 ℃; and/or, the drying time in the step (3) is 10-30 min.
  13. 13. The method of preparing a maillard film of claim 9 wherein the pressing means of step (4) comprises hot-press micro-forming; The hot-pressing micro-forming temperature is 80-120 ℃; And/or the application pressure of the hot-press micro-forming is 0.3-0.8 MPa; And/or the pressure maintaining time of the hot-press micro-forming is 10-30 s; and/or the hot-pressing die used for hot-pressing micro-forming is a die with a reticulate pattern array structure.
  14. 14. A lithium battery pole group, characterized in that the lithium battery pole group is coated with a mylar film according to any of claims 1-8.
  15. 15. The lithium battery pole group of claim 14, wherein the mylar film exhibits an integrally bent structure after wrapping the lithium battery pole group, comprising a top surface, a first side surface, a bottom surface, and a second side surface that are connected to each other; Wherein the mylar film at least partially overlaps at the first side or the second side.

Description

Mylar film, preparation method thereof and lithium battery pole group Technical Field The invention belongs to the technical field of battery materials, and relates to a Mylar film, in particular to a Mylar film, a preparation method thereof and a lithium battery pole group. Background The Mylar film (MYLAR FILM) is also called a polyester film, has excellent insulating property, mechanical strength and chemical corrosion resistance, is a core material for coating the lithium battery pole group, is mainly used for isolating the pole group and preventing short circuit, and plays roles of protecting the pole group and fixing pole pieces. Along with the development of the lithium battery to the high-rate, long-cycle, high-capacity and high-energy density directions, higher requirements are put forward on the electrolyte infiltration performance of the electrode group, namely, the electrolyte needs to infiltrate the inside of the electrode group rapidly and uniformly, the liquid injection time and the formation time are reduced, the problems of top dry area, bottom effusion and the like of the electrode group are avoided, and the cycle performance and the rate performance of the lithium battery are improved. In the prior art, in order to improve the liquid absorption and electrolyte infiltration performance of the Mylar film, related improvements are mainly focused on the following aspects that firstly, through holes or grooves are formed on the surface of the Mylar film, the infiltration speed is accelerated by increasing the contact area and the circulation channel of the electrolyte, secondly, protruding points or stripes are arranged on the surface of the Mylar film, the spreading capacity of the electrolyte is enhanced, and thirdly, the directional drainage of the electrolyte is realized by adopting a capillary structure or an integrally formed runner. However, the improvement scheme has obvious defects that the insulating structure of the Mylar film can be damaged by simply arranging the through holes, the insulating pressure resistance is reduced, scraps are easy to generate at the edges of the through holes, short circuit risks are easy to occur when the scraps fall into the polar group, the problem of uneven infiltration and dry top areas still can occur due to poor directionality of electrolyte infiltration caused by simply arranging the grooves or the convex points, the liquid retaining capacity of the Mylar film cannot be improved, the processing difficulty of a capillary structure or an integrally formed runner is high, the cost is high, the runner is easy to block, and the infiltration performance can be obviously reduced after long-term use. In addition, the surface energy of the existing Mylar film is low, the compatibility with electrolyte is poor, and the infiltration speed and the liquid retaining effect of the electrolyte are further restricted. Therefore, how to provide a mylar film for coating a lithium battery pole group, which can not only improve the electrolyte infiltration performance and solve the uneven infiltration problem, but also ensure the insulation strength and avoid the risk of chip falling and short circuit, and meanwhile ensure the simple process and the controllable cost, thus becoming the problem to be solved by the current technicians in the field. Disclosure of Invention Aiming at the defects of the prior art, the invention aims to provide a Mylar film, a preparation method thereof and a lithium battery pole group, which can not only improve the electrolyte infiltration performance and solve the uneven infiltration problem, but also ensure the insulation strength, avoid the risk of chip falling and short circuit, and simultaneously ensure the simple process and the controllable cost. In order to achieve the aim of the invention, the invention adopts the following technical scheme: in a first aspect, the present invention provides a mylar film comprising a polyester base film and a functional layer disposed on at least one side surface of the polyester base film. The functional layer is provided with reticulate patterns array which are distributed in a gradient way on the surface of one side far away from the polyester base film, and adjacent reticulate patterns are communicated with each other to form a capillary liquid guide channel. The depth of the reticulation is smaller than the thickness of the functional layer, and the reticulation array has lyophilic property. In a second aspect, the present invention provides a method for preparing a maillard film according to the first aspect, comprising the steps of: (1) Preparing a lyophile coating slurry; (2) Pretreating at least one side surface of a polyester base film; (3) Coating the lyophile coating slurry on the surface of the pretreated polyester base film, and drying to form a functional layer; (4) And pressing a reticulate pattern array with gradient arrangement density on the surface of the functional layer to ob