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US-20260128418-A1 - SILICONE-BASED FIRE PROTECTION SHEET, ITS PRODUCTION PROCESS, AND BATTERY PACKAGE HAVING THE SHEET

US20260128418A1US 20260128418 A1US20260128418 A1US 20260128418A1US-20260128418-A1

Abstract

The present disclosure relates to a silicone-based fire protection sheet, its production process and battery package having the sheet. The silicone-based fire protection sheet having a structure in which that at least one thermally insulative filler selected from aerogel particles, hollow particles and mesoporous particles are bound in a silicone-based polymeric binder. The amount of the thermally insulative filler ranges from 5 to 40 mass %, and the amount of the silicone-based polymeric binder ranges from 57.5 to 95 mass %, when the total mass of solid content for the silicone-based fire protection sheet is 100 mass %.

Inventors

  • Xiangyang Tai
  • Bizhong Zhu
  • Fuming Huang

Assignees

  • DOW SILICONES CORPORATION

Dates

Publication Date
20260507
Application Date
20220916

Claims (19)

  1. 1 . A silicone-based fire protection sheet having a structure in which at least one thermally insulative filler selected from aerogel particles, hollow particles and mesoporous particles are bound in a silicone-based polymeric binder, wherein the amount of the thermally insulative filler ranges from 5 to 40 mass %, the amount of the silicone-based polymeric binder ranges from 57.5 to 95 mass % when the total mass of solid content for the silicone-based fire protection sheet is 100 mass %.
  2. 2 . The silicone-based fire protection sheet according to claim 1 , wherein the thermally insulative filler has an average size of from 1 μm to 1.20 mm, and at least 50 mass % of the silicone-based polymeric binder is cured silicone.
  3. 3 . The silicone-based fire protection sheet according to claim 1 , wherein the aerogel particles have an average size ranging from 0.01 to 1.0 mm in an amount ranging from 15 to 35 mass % when the total mass of solid content for the silicone-based fire protection sheet is 100 mass %.
  4. 4 . The silicone-based fire protection sheet according to claim 1 , wherein the silicone-based polymeric binder is a water-based silicone polymeric binder.
  5. 5 . The silicone-based fire protection sheet according to claim 1 , wherein the silicone-based polymeric binder contains a water-based silicone polymeric binder comprising colloidal silica.
  6. 6 . The silicone-based fire protection sheet according to claim 1 , wherein the silicone-based polymeric binder further comprises at least one selected from the group consisting of flame-retardant additive, curing catalyst, rheology modifier, anti-foaming additive, wetting-additive, surface treatment agent, colorant, filler other than the thermally insulative filler, anti-oxidant additive, biocide, ultraviolet (UV) stabilizer additive and adhesion promoter additive.
  7. 7 . The silicone-based fire protection sheet according to claim 1 , which is applied for battery package.
  8. 8 . A battery package structure wherein the silicone-based fire protection sheet according to claim 1 is fully or partially arranged into a space between at least two adjacent individual battery cells.
  9. 9 . The battery package structure according to claim 8 , wherein the shape of battery is prismatic or pouch.
  10. 10 . The battery package structure according to claim 8 , wherein the silicone-based fire protection sheet is a silicone-based sheet which is cured prior to its arranging into the space between at least two adjacent individual battery cells.
  11. 11 . The battery package structure according to claim 8 , wherein the silicone-based fire protection sheet is a cured silicone-based product through curing reaction of a curable silicone-based composition in the space between at least two adjacent individual battery cells.
  12. 12 . An aqueous curable silicone-based composition which forms into the silicone-based fire protection sheet according to claim 1 through curing reaction, comprising: (A) a silicone-based polymeric binder containing at least 50 mass % of curable silicone polymer in an amount ranging from 57.5 to 95 mass %; (B) at least one thermally insulative filler selected from aerogel particles, hollow particles and mesoporous particles in an amount ranging 5 to 40 mass %; (C) a curing agent; and (D) water; (E) optionally, at least one component selected from the group consisting of flame-retardant additives, curing catalysts, rheology modifiers, anti-foaming additives, wetting-additives, surface treatment agents, colorants, fillers other than the thermally insulative fillers, anti-oxidant additives, biocides ultraviolet (UV) stabilizers, and adhesion promoters; when the total mass of solid content for the silicone-based fire protection sheet is 100 mass %.
  13. 13 . The aqueous curable silicone-based composition according to claim 12 , wherein component (A) is a silicone-based polymeric binder containing a curable silicone polymer and other curable/polymerizable materials, in which the other curable/polymerizable materials are in amount of 0 mass % to 30 mass %.
  14. 14 . The aqueous curable silicone-based composition according to claim 12 , wherein component (A) is emulsified or homogeneously dispersed into water (D).
  15. 15 . A method of producing a silicone-based fire protection sheet, the method comprising following steps: (I) coating the aqueous curable silicone-based composition according to claim 12 as a wet-slurry layer onto a substrate which optionally has a release layer; and (II) forming the silicone-based fire protection sheet by removing water from the aqueous curable silicone-based composition as coated under a temperature up to 140° C., following step (I).
  16. 16 . The method of producing the silicone-based fire protection sheet according to claim 15 , wherein the wet-slurry layer of the aqueous curable silicone-based composition has a thickness of from 0.2 to 10.0 mm in step (I).
  17. 17 . The method of producing the silicone-based fire protection sheet according to claim 15 , further comprising the step of (III) controlling the viscosity and/or flowability of the aqueous curable silicone-based composition by adding water and/or a rheology modifier before or at the same timing of step (I).
  18. 18 . A method of producing the battery package structure according to claim 8 , comprising a step of arranging the silicone-based fire protection sheet fully or partially into a space between at least two adjacent individual battery cells.
  19. 19 . A method of producing a battery package structure, the method comprising following steps: (B-I) filling a space between at least two adjacent individual battery cells fully or partially with the aqueous curable silicone-based composition according to claim 12 as a wet-slurry layer; and (B-II) forming a silicone-based fire protection sheet in the space between at least two adjacent individual battery cells by removing water from the aqueous curable silicone-based composition as coated under a temperature up to 140° C., following step (B-I).

Description

FIELD OF TECHNOLOGY The present disclosure relates to a silicone-based fire protection sheet, its production process and battery package having the sheet; relates to use of silicone-based fire protection sheet in the battery package; and relates to a method for producing the battery package using the silicone-based fire protection sheet. BACKGROUND ART To control the carbon dioxide emission into atmosphere and suppress the global warming from green-house gas effect, the production of electric vehicle (EV) powered by rechargeable lithium-ion battery (LIB) has started to surge in main geographies on the globe. To increase mileage per charge, EV battery manufactures are targeting at higher energy density battery cathode and anode materials. Meanwhile, the risk of triggering thermal runaway propagation is increasing along with higher energy density, due to the adoption of nickel based lithium metal oxide with higher Ni %. To control the risk of thermal runaway propagation in a battery pack with prismatic or pouch cell, a thermal insulation sheet is placed between two adjacent individual battery cells as a typical passive strategy. Once a thermal runaway happens on one cell, so called fired cell, the temperature inside the cell increases rapidly to 400° C. or above, e.g., 600° C., 800° C. or even 1000° C. Accordingly, the surface of the cell becomes hot, with temperature going beyond 350° C. or above, e.g., 550° C., 750° C. or 950° C. Thermal insulation sheet can delay the heat transfer from the hot surface of the fired cell to the adjacent good cell. Typical thermal insulation sheet adopted by the industry is aerogel sheet with aerogel powders compacted in a fabric mat. Aerogel powders may ensure thermal insulation performance, and the fabric mat holds the powders together into the shape of a sheet. However, because of its intrinsic low density and poor Van der Waal's force between particles, aerogel powders on sheet surface can easily diffuse into atmosphere during handling. That causes pollution to working environment. How to develop fire protection sheet with good thermal insulation performance and clean working environment for battery assembly process is a strong demand in EV battery industry. Silicone rubber can be ceramified at temperatures triggering its decomposition and condensation reaction. By adding thermally insulative fillers, e.g., aerogel powders or hollow glass beads, into liquid silicone rubber, and then making it cured and/or foamed, the resulted sheet has silicone rubber as matrix with thermally insulative fillers dispersed in. When one cell goes to thermal runaway, silicone matrix in the adjacent sheet can undergo ceramification, changing from soft rubber into rigid inorganic ceramics. Theoretically the sheet after ceramification can delay the heat diffusion from the fire cell to adjacent good cell. On the other hand, as thermally insulative fillers are well bound by silicone rubber, the sheet does not cause air pollution in working environment. However, too much loading of thermally insulative filler into liquid silicone rubber leads to too high viscosity to fit coating process. The pad or sheet fabrication in mass production defines upper limitation of filler volumetric loading in liquid silicone rubber. Within the limitation, thermal insulation performance of final sheet may not be sufficient to prevent thermal runaway propagation. How to develop a fire protection sheet with silicone rubber to bind enough loading of thermally insulative filler together still remained as a challenge. The invention disclosed a silicone based fire protection sheet for battery pack to effectively prevent the propagation of thermal runaway from a cell in fire to the adjacent ones. The sheet uses silicone to bind thermally insulative fillers like aerogel powder, with thermally insulative filler content from 5 to 40 mass %, and with silicone content>10 mass %, or with polymeric binder content>50 mass %. Below is a more detailed summary of the relevant prior arts found. No prior art has disclosed a battery pack within which a silicone bound aerogel sheet is used, especially sheets with aerogel particle content from 5 to 40 mass %, and with silicone content>10 mass %, or with polymeric binder content>50 mass %. CN108793932A claims a thermal-insulating energy-saving material and its preparation method, composed of the following raw materials in parts by weight: 30-60 parts of silicon dioxide aerogel, liquid resin, 10-30 parts of modified vitrified micro-bead, 30-50 parts of the closed expanded perlite, 10-20 parts of light aggregate, 8-15 parts of high viscosity clay, 2-8 parts of volcanic ash, 15-35 parts of inorganic fiber, 2-10 parts of dimethyl silicon oil, 1-5 parts of water glass, 2-6 parts of liquid resin 0.5-1.5 parts of dispersant and 40-60 parts of deionized water. Material of this invention has low heat conduction coefficient, low water absorption rate. In the preparation method, it claimed to first hea