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CN-122003774-A - Color coded ceramic coated battery separator

CN122003774ACN 122003774 ACN122003774 ACN 122003774ACN-122003774-A

Abstract

Disclosed herein are ceramic coated microporous polyolefin membranes having a contrast agent incorporated into the polyolefin membrane or ceramic coating. The contrast agent may include dyes, pigments, inorganic oxides, and/or other materials that impart color to the film or coating. The contrast agent enables an easy determination of which side of the membrane comprises the ceramic coating. Such ceramic coated polyolefin films can be used as separators to improve manufacturability, performance, and safety of energy storage devices such as lithium ion batteries.

Inventors

  • R.W. Pekara
  • D. Spiez
  • C. Lynch
  • S. BUTLER
  • W J Wood

Assignees

  • 阿姆泰克研究国际公司

Dates

Publication Date
20260508
Application Date
20250117
Priority Date
20240117

Claims (15)

  1. 1. A freestanding microporous polyolefin film, comprising: A microporous polyolefin substrate film having a coated side and an uncoated side, and A ceramic coating disposed on the first major surface of the microporous polyolefin substrate film, the ceramic coating comprising inorganic particles and forming the coated side of the microporous polyolefin substrate film; Wherein one of the microporous polyolefin substrate film or the ceramic coating comprises a contrast agent that allows the coated side and the uncoated side of the microporous polyolefin substrate film to be visually distinguishable.
  2. 2. The free-standing microporous polyolefin membrane of claim 1, wherein the ceramic coating comprises sufficient coating weight to impart high temperature dimensional stability defined by an area shrinkage of < 5% at a temperature above the melting point of the polyolefin.
  3. 3. The free-standing microporous polyolefin film of claim 1 or 2, wherein the contrast agent comprises at least one of a pigment or a dye.
  4. 4. The free standing microporous polyolefin film of claim 3, wherein the contrast agent comprises a water soluble dye.
  5. 5. The free-standing microporous polyolefin film of claim 3, wherein the contrast agent comprises a pigment comprising at least one of a metal oxide, carbon, carbide, or mixtures thereof.
  6. 6. The free-standing microporous polyolefin film of any of claims 1 to 5, wherein the microporous polyolefin substrate film comprises the contrast agent.
  7. 7. The free-standing microporous polyolefin film of any of claims 1 to 6, wherein the ceramic coating comprises the contrast agent.
  8. 8. An energy storage device comprising the freestanding microporous polyolefin film of any one of claims 1 to 7.
  9. 9. A method of forming a freestanding microporous polyolefin film, the method comprising: obtaining a microporous polyolefin substrate film having a first major surface and a second major surface, and Applying a ceramic coating to the first major surface of the microporous polyolefin substrate film, the ceramic coating comprising inorganic particles and forming a coated side of the microporous polyolefin substrate film; Wherein one of the microporous polyolefin substrate film or the ceramic coating comprises a contrast agent that allows the coated side of the microporous polyolefin substrate film to be visually distinguishable from the uncoated side of the microporous polyolefin substrate film.
  10. 10. The method of claim 9, wherein the ceramic coating comprises sufficient coating weight to impart high temperature dimensional stability defined by an area shrinkage of < 5% at a temperature above the melting point of the polyolefin.
  11. 11. The method of claim 9 or 10, wherein the contrast agent comprises at least one of a pigment or a dye.
  12. 12. The method of claim 11, wherein the contrast agent comprises a water-soluble dye.
  13. 13. The method of claim 11, wherein the contrast agent comprises a pigment comprising at least one of a metal oxide, carbon, carbide, or mixtures thereof.
  14. 14. The method of any one of claims 9 to 13, wherein the microporous polyolefin substrate film comprises the contrast agent.
  15. 15. The method of any one of claims 9 to 13, wherein the ceramic coating comprises the contrast agent.

Description

Color coded ceramic coated battery separator RELATED APPLICATIONS The present application claims priority from U.S. provisional application No. 63/621,852, filed on 1 month 17 of 2024, entitled Color-Coded, ceramic-Coated Battery Separator [ Color-Coded Ceramic-coated battery separator ], which is incorporated herein by reference in its entirety. Copyright statement Is available from International liability company (AMTEK RESEARCH International LLC) under study 2025 An Teke. A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the patent and trademark office patent file or records, but otherwise reserves all copyright rights whatsoever. 37 CFR (computational fluid dynamics) 1.71(d)。 Technical Field The present invention relates to the formation of ceramic coated microporous polyolefin membranes wherein a contrast agent is incorporated into the polyolefin membrane or ceramic coating to highlight which side is coated. The contrast agent may be a dye, pigment, inorganic oxide, or other material that imparts a color to the film or coating. Such ceramic coated polyolefin films can be used as separators to improve manufacturability, performance, and safety of energy storage devices such as lithium ion batteries. Background The separator is an integral part of the performance, safety and cost of lithium ion batteries. During normal operation, the primary function of the separator is to prevent electron conduction (i.e., short circuit or direct contact) between the anode and cathode, while allowing ionic conduction via the electrolyte. Under abusive conditions (such as external short circuit or overcharge), the separator is required to close pores (shutdown) at temperatures well below which thermal runaway may occur. Closed cells are caused by the collapse of the pores in the separator due to melting and viscous flow of the polymer, thereby slowing or stopping the flow of ions between the electrodes. Almost all Li-ion battery separators contain polyethylene as part of a single layer or multi-layer construction such that closed cells begin at about 130 ℃ (i.e., the melting point of the polyethylene). Separators for the lithium ion market are currently manufactured via either the "dry" or "wet" processes. In the dry process, polypropylene (PP) or Polyethylene (PE) is extruded into a sheet and subjected to rapid drawing. The sheet is then annealed at 10 ℃ to 25 ℃ below the polymer melting point so that crystallite size and orientation are controlled. Next, the sheet is rapidly stretched in the Machine Direction (MD) to achieve slit-like voids or interstices. Three-layer PP/PE/PP separators produced by dry process are commonly used in lithium ion rechargeable batteries. Wet separators composed of high molecular weight polyethylene are produced by extruding an oil/polymer mixture at elevated temperature followed by phase separation, biaxial stretching, and extraction of process oil (i.e., plasticizer). The resulting separator has oval or spherical pores with good mechanical properties in both the machine and cross directions. PE-based separators manufactured in this way using cast film or blown film techniques have been widely used in Li-ion batteries. In the case of large format Li-ion battery cells designed for hybrid, plug-in hybrid or electric vehicle applications (HEV, PHEV, EV), the benefits of diaphragm closed cells have been questioned publicly, as it is difficult to ensure that the closed cells have adequate rate and uniformity throughout the entire cell. The main reason is that after closed cells, residual stresses above the melting point of the polymer and reduced mechanical properties may lead to shrinkage, tearing or pinhole formation. The exposed electrodes may then contact and create internal shorts, resulting in more heating, thermal runaway, and explosion. Therefore, battery manufacturers have focused on using separators having excellent high-temperature in-plane stability. In U.S. patent application publication No. 20190097196 A1, a method for producing an aromatic polyamide film (e.g., polymetaphenylene isophthalamide) for use as a Li-ion battery separator is described. Such polymers have glass transition temperatures above 300 ℃ and thermal decomposition temperatures above 500 ℃. In an alternative method, a microporous polyolefin membrane is coated with ceramic particles and a binder (e.g., a polymeric binder) on one or both sides. At sufficient loading levels, the ceramic will impart high temperature dimensional stability, defined as < 5% area shrinkage at temperatures above the melting point of the polyolefin. The ceramic layer also protects the polyolefin from oxidation when in contact with the high voltage cathode (e.g., NMC 622) and its tortuous pore structure mitigates dendrite growth. In the case