Search

EP-4609460-B1 - SILICONE-BASED THERMAL INSULATION MATERIALS FOR BATTERY MODULES

EP4609460B1EP 4609460 B1EP4609460 B1EP 4609460B1EP-4609460-B1

Inventors

  • SHAO, YAN
  • EDMAIER, Sandra
  • FAYBRICK, Daryl
  • KALCHAUER, Michael
  • POLCHINSKI, Laura

Dates

Publication Date
20260506
Application Date
20231009

Claims (14)

  1. An electric vehicle battery assembly, comprising: a) an array of a plurality of individual metal ion batteries; b) optionally, a frame laterally surrounding the array of the plurality of individual metal ion batteries; c) optionally, a lower cover; d) an upper cover; and e) disposed between the array of a plurality of batteries and at least one of the lower cover and/or upper cover, a crosslinked, sprayable and thixotropic addition-curable or moisture-curable silicone composition comprising greater than 50 weight percent and less than 85 weight percent of aluminum trihydrate-containing filler based on the total weight of the curable silicone composition, aluminum trihydrate particles of the filler comprising at least 30 weight percent of the curable silicone composition, and at least one ceramifying additive which promotes ceramification of the crosslinked silicone composition on exposure to temperatures of 600 °C or higher, wherein the crosslinked silicone composition reduces heat transfer from a surface of the crosslinked silicone composition nearest the array of a plurality of batteries to an outside surface of said lower cover or said upper cover bearing the crosslinked silicone composition, such that the outside surface does not reach a temperature of 350°C for a period of at least two minutes when the surface of the crosslinked silicone composition nearest the array of a plurality of batteries is exposed to a heat source having a temperature greater than 850°C, positioned 2.5 cm from the surface of the organosilicon composition, and when determined in accordance with the method outlined in the description.
  2. The electric vehicle battery assembly of claim 1, wherein the array of a plurality of individual batteries is in the form of battery modules, each module containing a second plurality of individual batteries, and the organosilicon composition is applied to the top cover of the battery assembly.
  3. The electric vehicle battery assembly of claim 1, wherein the sprayable, thixotropic silicone composition is an at least two component, addition-curable silicone composition, comprising: a) a first component, comprising: i) at least one vinyl-functional polyorganosiloxane having a viscosity less than 4000 mPa·s, preferably less than 1000 mPa·s, in an amount of from 20-70 weight percent based on the total weight of all organosilicon compounds; ii) optionally, one or more silanol-stopped polyorganosiloxanes or non-functional polyorganosilanes having a viscosity of less than 10,000 mPa·s, preferably less than 1000 mPa·s, in an amount of 20-40 weight percent based on the total weight of all organosilicon compounds; iii) at least one silane adhesion promoter; iv) at least one hydrosilylation catalyst; v) optionally, a filler; and b) a second component, comprising: i) at least one Si-H-functional crosslinker; ii) optionally one or more silanol-stopped organopolysiloxanes or non-functional polyorganosiloxanes having a viscosity of less than 10,000 mPa·s, preferably less than 1000 mPa·s; iii) optionally, one or more silane adhesion promoters; iv) optionally, a filler, wherein at least one of the first and second components contains a filler comprising aluminum trihydrate, the total amount of filler present among all components being from 50 weight percent to 85 weight percent and aluminum trihydrate being present in the filler(s) in an amount sufficient to provide at least 30 weight percent aluminum trihydrate, preferably at least 50 weight percent aluminum trihydrate, more preferably at least 70 weight percent aluminum trihydrate, and most preferably at least 80 weight percent aluminum trihydrate, based on the total weight of all components; a silicone thermal stabilizer; and wherein at least one component contains said ceramifying additive, preferably a ceramifying additive containing platinum; and wherein at least one of the components contains a silane adhesion promoter, where viscosity is determined in accordance with the method outlined in the description.
  4. The electric vehicle battery assembly of claims 1 or 3, further comprising up to 5 weight percent of a thermal stabilizer composition comprising titanium dioxide.
  5. The electric vehicle battery assembly of claims 1 or 2, wherein the sprayable, thixotropic silicone composition is a moisture-curable silicone composition, comprising; i) at least one silanol-stopped polyorganosiloxane having a viscosity of less than 10,000 mPa·s, in an amount greater than 90 weight percent based on the total weight of the organosilicon components; ii) at least one ceramifying additive which promotes ceramification of the organosilicon composition; iii) optionally from 0.01-2 weight percent of an emulsion of water and silicone; iv) at least one alkoxysilane crosslinker; v) optionally, an adhesion promoter different from component iv); and iv) from 50-85 weight percent of aluminum trihydrate-containing filler in an amount sufficient to supply at least 30 weight percent of aluminum trihydrate based on the total weight of the silicone composition, and v) at least one thermal stabilizer, where viscosity is determined in accordance with the method outlined in the description.
  6. The electric vehicle battery assembly of claim 5, wherein the moisture-curable silicone composition is an at least two component composition, one component comprising an emulsion of water and silicone and a silanol-stopped organopolysiloxane, and a second component comprising an alkoxysilane crosslinker.
  7. The electric vehicle battery assembly of claim 5, wherein the silicone thermal stabilizer comprises titanium dioxide, in an amount sufficient to supply from 0.1 to 3 weight percent of titanium dioxide based on the total weight of the silicone composition, preferably from 0.2 to less than 2 weight percent of titanium dioxide.
  8. A heat resistant crosslinkable organosilicon composition useful for manufacturing the metal ion vehicle battery assemblies of claim 1, which is sprayable and thixotropic, comprising: an addition-curable or moisture-curable silicone composition containing greater than 50 weight percent and less than 85 weight percent of aluminum trihydrate-containing filler based on the total weight of the curable silicone composition, and sufficient to provide at least 30 weight percent aluminum trihydrate, preferably at least 50 weight percent aluminum trihydrate, more preferably at least 70 weight percent aluminum trihydrate, and most preferably at least 80 weight percent of aluminum trihydrate based on the total weight of the organosilicon composition, a silicone thermal stabilizer, and at least one ceramifying additive which promotes ceramification of the organosilicon composition, wherein the curable silicone composition, following crosslinking to form a crosslinked silicone, reduces heat transfer, from a side of a metal substrate on which said crosslinked silicone composition is coated, to an opposing side of said metal substrate, such that the opposing side of the metal substrate does not reach a temperature of 350°C or more for a period of at least two minutes when the side of the crosslinked silicone composition opposite the metal substrate is exposed to a heat source which causes the temperature of the surface of the crosslinked silicone to rise above 600 °C, when determined in accordance with the method outlined in the description.
  9. The heat resistant crosslinkable organosilicon composition of claim 8 which is a sprayable thixotropic multiple-component addition-curable silicone composition comprising at least two components as follows: a) a first component, comprising: i) at least one vinyl-functional polyorganosiloxane having a viscosity less than 4000 mPa·s, preferably less than 1000 mPa·s, in an amount of from 20-70 weight percent based on the total weight of all organosilicon components; ii) optionally, at least one silanol-stopped polyorganosiloxane or non-functional polyorganosiloxane having a viscosity of less than 10,000 mPa·s, preferably less than 1000 mPa·s, in an amount of less than 30 weight percent based on the total weight of all organosilicon compounds; iii) optionally, a silane adhesion promoter; iv) at least one hydrosilylation catalyst; v) optionally, a filler; and b) a second component, comprising: i) at least one Si-H crosslinker; ii) optionally, one or more silanol-stopped organopolysiloxanes or non-functional organopolysiloxanes having a viscosity of less than 10,000 mPa·s, preferably less than 1000 mPa·s, in an amount of less than 30 weight percent based on the total weight of all organosilicon components; iii) optionally, one or more silane adhesion promoters; iv) optionally, a filler, wherein at least one component contains an aluminum trihydrate-containing filler, the total amount of aluminum trihydrate-containing filler present among all components being from 50 weight percent to 85 weight percent, and sufficient to provide at least 30 weight percent of aluminum trihydrate, preferably at least 50 weight percent of aluminum trihydrate, more preferably at least 70 weight percent of aluminum trihydrate, and most preferably at least 80 weight percent of aluminum trihydrate, based on the total weight of the curable silicone composition; at least one component contains a ceramifying additive which promotes ceramification of the organosilicon temperatures at a temperature of 600 C or greater, at least one component comprises a silicone thermal stabilizer comprising titanium dioxide, and at least one component contains a silane adhesion promoter, where viscosity is determined in accordance with the method outlined in the description.
  10. A sprayable, thixotropic, moisture-curable organosilicon composition, suitable for manufacturing the metal ion vehicle batter assemblies of claim 1, comprising: i) at least one silanol-stopped polyorganosiloxane having a viscosity of less than 10,000 mPa·s, preferably less than 1000 mPa·s, in an amount greater than 90 weight percent based on the total weight of organosilicon components of the organosilicon composition; ii) a silicone thermal stabilizer; and iii) at least one ceramifying additive which promotes ceramification of the organosilicon composition at a temperature of 600 °C or more; iv) optionally, from 0.01-2 weight percent of an emulsion of silicone and water; and v) from 50-85 weight percent of aluminum trihydrate-containing filler based on the total weight of the organosilicon composition, containing sufficient aluminum trihydrate to provide at least 30 weight aluminum trihydrate, preferably at least 50 weight percent aluminum trihydrate, more preferably at least 70 weight percent aluminum trihydrate, and most preferably at least 80 weight percent aluminum trihydrate, based on the total weight of the organosilicon composition, wherein the moisture-curable organosilicon composition, following curing to form a crosslinked silicone composition, reduces heat transfer from a side of a metal substrate on which said crosslinked silicone composition is coated to an opposing side of said metal substrate such that the opposing side of the metal substrate does not reach a temperature of 350°C or more for a period of at least two minutes, preferably at least five minutes, and more preferably at least 8 minutes, when the side of the crosslinked silicone composition opposite the metal substrate is exposed to a heat source having a temperature of 850°C positioned 2.5 cm from the surface of the crosslinked silicone, where viscosity is determined in accordance with the method outlined in the description.
  11. The moisture-curable organosilicon composition of claim 10, wherein the moisture-curable silicone composition is an at least two component composition, one component comprising an emulsion of water in silicone and a silanol-stopped organopolysiloxane, and a second component comprising an alkoxysilane crosslinker and a condensation catalyst.
  12. The organosilicon composition of any of claims 9 or 10, wherein the silicone thermal stabilizer comprises titanium dioxide, in an amount sufficient to supply from 0.1 to 3 weight percent of titanium dioxide based on the total weight of the organosilicon composition, preferably from 0.2 to less than 2 weight percent of titanium dioxide.
  13. A method for the manufacture of a metal ion battery module and/or battery pack of claim 1 or 2, comprising: a) assembling a plurality of individual metal ion battery cells into a battery module, and optionally assembling a plurality of said battery modules into a battery pack; b) providing at least a top metal cover dimensioned to enclose at least a top surface of the battery module and/or battery pack, and optionally a bottom metal cover dimensioned to enclose at least a bottom surface of the battery module and/or battery pack; c) applying to at least the top metal cover, a flowable and sprayable, thixotropic crosslinkable organosilicon composition comprising addition-curable organosilicon components or moisture-curable organosilicon components, and an aluminum trihydrate-containing filler in an amount of from 50-85 weight percent based on the total weight of the organosilicon composition, the amount of the aluminum trihydrate-containing filler and the aluminum trihydrate-proportion of the aluminum trihydrate-containing filler being such so as to supply at least 30 weight percent aluminum trihydrate, more preferably at least 50 weight percent aluminum trihydrate, yet more preferably at least 70 weight percent aluminum trihydrate, and most preferably at least 80 weight percent aluminum trihydrate based on the weight of the organosilicon composition, and further comprising a silicone thermal stabilizer and at least one ceramifying additive; d) mounting the top metal cover over the plurality of metal ion battery cells or battery modules, wherein the crosslinkable organosilicon composition, following crosslinking to form a crosslinked silicone, reduces heat transfer from a side of the metal substrate on which said crosslinked silicone composition is coated to an opposing side of said metal substrate, such that the opposing side of the metal substrate does not reach a temperature of 350°C or more for a period of at least two minutes when the side of the crosslinked silicone composition opposite the metal substrate is exposed to a heat source which causes the temperature of the crosslinked silicone to rise above 600 °C, when determined in accordance with the method outlined in the description.
  14. An ion battery module or battery pack, prepared by the method of claim 13.

Description

FIELD OF THE INVENTION The invention is directed to an improvement in battery modules which are suitable for applications requiring large amounts of electrical energy, such as batteries for electrical vehicles. DESCRIPTION OF THE RELATED ART In the past, when it was desired to store electrical energy in a rechargeable manner, lead-acid batteries were widely used. These batteries, however, have well-known disadvantages. Among these disadvantages are a very high mass and therefore a relatively low energy density, the use of lead which is environmentally disfavored, and the presence of very strong sulfuric acid with its obvious disadvantages. Nickel cadmium batteries offered an improvement in storage density, but were and are relatively expensive. Their use had been primarily limited to power tools and consumer electrical products. Moreover, the energy storage density of nickel cadmium batteries is still not as high as desired. Recently, lithium ion batteries have become ubiquitous due to their higher energy storage capacity, and have been used more recently to power electrical vehicles, which was impossible with lead acid batteries due to their high weight. The lithium ion batteries employed in large-scale applications such as electrical vehicles are not produced as single batteries, but rather are produced as individual canisters or "cells" which are then assembled into modules. The cells may be cylindrical, rectangular, or in any particular shape. An electric vehicle "battery" may consist of one or more of such modules connected together electrically. While these modules might be a single, large module consisting of a plurality of individual cells, it is more common at present to assemble a plurality of these modules to form a "battery pack". These battery packs minimally comprise a frame containing the modules, a top cover, and a bottom cover. Depending upon the vehicle design and other characteristics, such as whether this vehicle is a solely electrical vehicle, a hybrid electric/gasoline vehicle, an electrically powered aircraft, or an industrial vehicle such as a "hi lo", the battery pack may also contain additional elements, such as stiffening ribs and the like. A "module" may also consist of a space with a frame or compartment holding a plurality of individual cells, rather than a self-supporting structure to be assembled into a battery pack. Lithium ion batteries are but one type of modern rechargeable, high energy density ion batteries which may be used in applications such as those described above. Virtually all of these types of batteries contain active elements, e.g. lithium, sodium, or aluminum, which render these batteries potentially flammable. Lithium ion batteries, for example, have been known to occasionally catch fire, and for this reason, are banned from checked luggage when flying. The potential for an incendiary event becomes more likely when such batteries are used in electric vehicles, as these vehicles may be involved in accidents which destroy the integrity of the battery pack or of individual battery modules. These types of incendiary events are even the more dangerous, as water which is commonly used to fight fires may actually increase the energy released. It is clear that it would be desirable to limit the amount of energy released during an incendiary event, in order that not only the occupants of the vehicle may be protected, but other flammable components of the electric vehicle may also be protected and prevented from burning. The top and bottom covers of the battery pack provide some degree of protection. However, these covers cannot be made inordinately thick without a significant weight penalty, and even if a thicker cover were possible, since the covers are constructed of metal, they would offer little impediment to thermal conduction. While there are many potential insulating materials, such as those based on pyrogenic silica, these fillers are difficult to employ in an industrial setting, and would be prone to liberate large quantities of silica particles in the case of an accident. Many other insulation materials are either expensive to produce or to apply, or cannot withstand the high temperatures which are conceivably encountered. Thus, it would be desirable to provide an economical means to thermally insulate the vehicle and its environs in the case of an incendiary event of the battery pack. US Patent 9,507,054 discloses silicon compositions having high optical reflectance and also flame retardant properties, which include a silicone resin, an organosilicon compound, aluminum hydroxide as a flame retardant, generally present in an amount of up to 45 weight percent, and a reflective filler comprising titanium dioxide. These compositions have very high viscosity, and are suitable for forming articles by processes such as injection molding, transfer molding, casting, extruding, over molding, compression molding, or cavity molding. The high viscosity prevents the econ