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CN-122000623-A - Battery diaphragm and secondary battery

CN122000623ACN 122000623 ACN122000623 ACN 122000623ACN-122000623-A

Abstract

The application relates to the technical field of battery diaphragms, in particular to a battery diaphragm and a secondary battery, wherein the battery diaphragm comprises a base film and a first adhesive coating, the base film is a porous film, the base film is provided with a first surface and a second surface which are oppositely arranged along the thickness direction of the base film, the first adhesive coating mainly comprises organic polymer particles and a binder, the first adhesive coating is coated on at least one surface of the first surface and the second surface, the distance D1 between two adjacent adhesive points in the first adhesive coating on the same surface is larger than the longest axis R of the adhesive points, R is smaller than D1 and smaller than 2R, when the first adhesive coating is arranged on the first surface and the second surface, the orthographic projection of the first adhesive coating on the first surface and the first adhesive coating on the second surface on the same surface of the base film is staggered, the impedance C between the battery diaphragm and a pole piece before and after hot pressing is smaller than 0.1 omega, and the ventilation P of the base film before and after the first adhesive coating is coated is smaller than 15s/100ml. The separator and the battery have better ionic conductivity, bonding property, energy density and cycle property.

Inventors

  • ZHANG HUI
  • DAI ZHUANGQIANG
  • LI WENCHAO
  • ZHANG WENLI
  • HE GUANYING

Assignees

  • 深圳中兴新材技术股份有限公司

Dates

Publication Date
20260508
Application Date
20260129

Claims (10)

  1. 1. A battery separator, comprising: a base film which is a porous film, the base film having a first face and a second face which are disposed opposite to each other in a thickness direction thereof, and The first adhesive dispensing coating is mainly composed of organic polymer particles and a binder, and is coated on at least one of the first surface and the second surface; When the first surface and the second surface are provided with the first adhesive coating, the orthographic projection of the first adhesive coating on the first surface and the orthographic projection of the first adhesive coating on the second surface on the same surface of the base film are staggered; The impedance increment C of the battery diaphragm and the pole piece before and after hot pressing is less than 0.1 omega, and the ventilation increment P of the base film before and after the first adhesive coating is coated is less than 15s/100ml.
  2. 2. The battery separator of claim 1 wherein the first adhesive coating on the first side has a coverage of M1,5% M1 50% and/or the first adhesive coating on the second side has a coverage of M2,0< M2 50%.
  3. 3. The battery separator of claim 1, wherein a distance D2 between two adjacent glue sites of orthographic projection of the first glue coating on the first side and the first glue coating on the second side on the same side of the base film is greater than a longest axis R of the glue sites, and R < D2<2R.
  4. 4. The battery separator of claim 3 wherein said glue sites of said first glue coating on said first side form at least one predetermined pattern on said first side and wherein an orthographic projection of at least one said glue site of said first glue coating on said second side on said first side is centered in said predetermined pattern.
  5. 5. The battery separator according to claim 4, wherein the glue sites of the first glue coating on the second face are arranged in one-to-one correspondence with the preset pattern.
  6. 6. The battery separator of claim 4, wherein the predetermined pattern is a circular, regular polygon or an array distribution structure.
  7. 7. The battery separator of claim 1, further comprising a second spot-size coating applied to the first face and/or the second face and offset from the first spot-size coating on the same face.
  8. 8. The battery separator of claim 1, further comprising a functional coating applied between the first face and/or the second face and the first adhesive coating, the functional coating comprising at least one of bonding, closed cell, heat resistance, flame retardance, ionic conduction enhancement, adsorption of transition metal elements, improved base film and electrolyte wettability.
  9. 9. The battery separator according to claim 1, wherein the battery separator satisfies at least one of the following conditions (1) to (4): (1) The value range of the longest axis R of the glue dot is 100-500 mu m; (2) The value range of the distance D1 between two adjacent glue points is 100-1000 mu m; (3) The shape of the first dispensing coating comprises at least one of a circle, an ellipse, a square, a diamond, a cross, a petal shape, a rice shape and a coffee ring shape; (4) The height h of the glue dot is 1-10 mu m.
  10. 10. A secondary battery comprising the battery separator according to any one of claims 1 to 9.

Description

Battery diaphragm and secondary battery Technical Field The application relates to the technical field of battery diaphragms, in particular to a battery diaphragm and a secondary battery. Background The secondary battery is used as a core power source of modern portable electronic equipment and electric automobiles, and the performance optimization of the secondary battery is always a research hot spot. The separator serves as a key inner layer component of the battery, and is mainly used for isolating the positive electrode from the negative electrode to prevent short circuit and simultaneously allowing free passage of lithium ions. Although the traditional polyolefin diaphragm (such as PE and PP) has good mechanical properties, the traditional polyolefin diaphragm has the problems of poor thermal stability (short circuit is caused by easy shrinkage at high temperature), poor wettability to electrolyte and the like. To solve these problems, the industry generally adopts a method of coating inorganic ceramic particles (such as alumina, silica) or organic polymer coating on the surface of the diaphragm. The existing coating technology mainly comprises full-face coating, namely, a layer of slurry is uniformly coated on the whole surface of the diaphragm, so that a continuous coating layer is formed on the surface of the base film. However, the coating of the full-face coating process increases the weight and thickness of the separator, reduces the energy density of the battery, and meanwhile, the excessively thick coating can prevent ion conduction and increase internal resistance, and meanwhile, the resistance of the battery is increased after hot pressing, the bonding interface between the full-face coating and the base film is large, and stripping can occur in long-term circulation, so that the service life of the battery is affected. Disclosure of Invention The present application provides a battery separator and a secondary battery to solve at least part or all of the above technical problems. The present application provides a battery separator comprising: a base film which is a porous film, the base film having a first face and a second face which are disposed opposite to each other in a thickness direction thereof, and The first adhesive dispensing coating is mainly composed of organic polymer particles and a binder, and is coated on at least one of the first surface and the second surface; When the first surface and the second surface are provided with the first adhesive coating, the orthographic projection of the first adhesive coating on the first surface and the orthographic projection of the first adhesive coating on the second surface on the same surface of the base film are staggered; The impedance increment C of the battery diaphragm and the pole piece before and after hot pressing is less than 0.1 omega, and the ventilation increment P of the base film before and after the first adhesive coating is coated is less than 15s/100ml. In some alternative embodiments, the coverage of the first spot size coating on the first side is M1,5% M1 50% and/or the coverage of the first spot size coating on the second side is M2,0< M2 50%. In some alternative embodiments, a distance D2 between two adjacent glue sites of orthographic projection of the first glue coating on the first side and the first glue coating on the second side on the same side of the base film is greater than a longest axis R of the glue sites, and R < D2<2R. In some alternative embodiments, the glue sites of the first glue coating on the first side form at least one preset pattern on the first side, and the orthographic projection of the at least one glue site of the first glue coating on the second side on the first side is positioned at the center of the preset pattern. In some alternative embodiments, the glue sites of the first glue coating on the second side are arranged in a one-to-one correspondence with the preset pattern. In some alternative embodiments, the predetermined pattern is a circle, regular polygon, or an array distribution structure. In some alternative embodiments, the battery separator further comprises a second dispensing coating applied to the first face and/or the second face and offset from the first dispensing coating on the same face. In some alternative embodiments, the battery separator further comprises a functional coating applied between the first face and/or the second face and the first bead coating, the functional coating comprising at least one of bonding, closed cell, heat resistant, flame retardant, ion conduction enhancing, adsorption of transition metal elements, improved base film wettability with electrolyte. In some alternative embodiments, the battery separator satisfies at least one of the following conditions (1) - (4): (1) The value range of the longest axis R of the glue dot is 100-500 mu m; (2) The value range of the distance D1 between two adjacent glue points is 100-1000 mu m; (3) The