Elastomeric silicone materials and their use

Abstract

An article suitable for housing a plurality of battery cells, such as battery modules, provides thermal insulation between adjacent battery cells using a thermal barrier layer comprising a ceramifiable elastomeric silicone material using fumed silica (amorphous SiO2) or fumed silica (amorphous SiO2) + quartz (crystalline SiO2). Also provided is the use of the ceramifiable elastomeric silicone material as a means to retard and / or prevent thermal runaway in such articles. Typically, the battery cells designed for use in this article are lithium-ion battery cells.

Description

[0001] The present disclosure relates to a battery module including a ceramizable elastomeric silicone material and the use of the ceramizable elastomeric silicone material as a means of delaying and / or preventing thermal runaway in a battery module, such as a lithium-ion battery module.

[0002] Rechargeable batteries such as lithium-ion batteries (also known as Li-ion batteries or LIBs) are increasingly being used in modules and / or groups of modules for various applications, such as electric vehicle batteries (EVBs) in electric and hybrid (electric and gasoline / diesel) driven vehicles, to reduce and ultimately eliminate the greenhouse gas emissions generated thereby. EVBs are battery packs used to power the propulsion systems of electric and hybrid vehicles and are therefore designed to provide power for sustained periods of time, unlike starting, lighting and ignition (SLI) batteries. Lithium-ion batteries are increasingly becoming the preferred option. For the avoidance of doubt in this disclosure and from a practical perspective regarding the space available, individual battery cells (sometimes referred to herein as cells) are arranged in battery modules, and a battery pack is constructed from a plurality of electrically interconnected battery modules.

[0003] The three main components in a lithium-ion battery are:

[0004] Anode (negative electrode);

[0005] cathode (positive electrode) and

[0006] electrolytes.

[0007] In use of lithium-ion batteries, lithium ions move from the anode through the electrolyte to the cathode during discharge, and move in the opposite direction during charging.

[0008] A variety of materials can be used as anodes in lithium-ion batteries, but by far the most commonly used is graphite. Currently, the preferred material for the cathode in lithium-ion batteries is selected from one of three materials:

[0009] (i) layered oxides (such as lithium cobalt oxide);

[0010] (ii) polyanions (such as lithium phosphate) or

[0011] (iii) Spinels (such as lithium manganese oxide).

[0012] Unlike rechargeable batteries with water-based electrolytes, lithium-ion batteries have potentially dangerous pressurized liquid electrolytes that can burn and require strict quality control during manufacturing. A large number of non-aqueous materials have been proposed and / or used as electrolytes in lithium-ion batteries. One example of a suitable electrolyte is a mixture of organic carbonates, such as ethylene carbonate and / or diethyl carbonate, containing a lithium ion source, such as lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate monohydrate (LiAsF6), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), and lithium trifluoromethanesulfonate (LiCF3SO3).

[0013] In order to provide power for sustained periods of time, i.e., to enable acceptable distances between recharging, EVBs are typically provided in the form of a battery pack that is mounted in a suitable space within the vehicle, such as a car trunk or luggage compartment, etc. Regardless of the location of the pack, the enclosure must protect the vehicle occupants from the lithium-ion batteries in the event of a failure.

[0014] When a lithium-ion battery cell fails (for any reason), the cell typically overheats and / or becomes overcharged, which can result in fire and / or explosion. Such failures may be caused, for example, by a short circuit, physical damage (i.e., being crushed), or being subjected to a higher electrical load without overcharge protection. If present in a multi-cell battery module of lithium-ion batteries, overheating of a first cell may propagate similar conditions in adjacent cells, causing multiple cells in the battery module to overheat and fail, potentially leading to "thermal runaway" and cell rupture.

[0015] Thermal runaway is typically triggered by a failure in one of the battery cells in a battery module, causing the cell to abnormally release heat and a sudden increase in the battery cell temperature. Once the temperature exceeds a threshold, such as approximately 150°C, the components in the failed cell trigger a self-heating, autocatalytic, and thermal decomposition exothermic reaction, causing the battery temperature to rise rapidly, for example, at a rate exceeding 20°C per minute, potentially reaching 500°C or even 1000°C. In the absence of good insulation and heat dissipation structures in the battery module containing the failed battery, the released heat energy can heat adjacent battery cells, leading to "thermal runaway" within the battery module. Once thermal runaway begins within the battery module, it cannot be effectively controlled and can result in an exothermic combustion reaction, followed by the release of large amounts of combustible electrolyte gases and battery material decomposition gases (e.g., CO2, CO, and H2), and potentially an explosion.

[0016] Circuitry has been developed to disconnect lithium ion cells (and battery modules) if / when the generated voltage exceeds a predefined safe voltage range for each cell or overcharging or discharging. However, lithium battery packs are still susceptible to the above-mentioned thermal runaway and cell rupture in the event of damage or malfunction.

[0017] Therefore, safety measures are provided to enable occupants to exit the vehicle in the event of such a malfunction and to protect the occupants from the direct risk of toxic gases entering the passenger cabin, for example by providing a robust battery pack that can withstand a certain pressure increase due to gas generation, and to maximize the potential impact of thermal runaway propagation between adjacent cells. One suggested solution is to provide a coated aerogel blanket material between adjacent battery cells in a battery module to slow down heat transfer.

[0018] However, the coated aerogel blanket material results in amorphous aerogel silica being dispersed into the working environment, requiring more protective equipment during cutting, packaging, storage, and transportation. Furthermore, while these materials provide good initial thermal insulation performance, the performance drops sharply due to a significant reduction in thickness as the pressure within the battery module increases.

[0019] An article is provided, the article being suitable for housing a plurality of battery cells, the article providing thermal insulation between adjacent battery cells by providing a thermal insulation layer of a ceramicizable elastomeric silicone material between adjacent battery cells, the ceramicizable elastomeric silicone material being a cured product of a silicone rubber composition, the silicone rubber composition comprising:

[0020] (i) one or more polydiorganosiloxanes having a weight average molecular weight of 200,000 g / mol to 800,000 g / mol, having 0.01 % to 1 % alkenyl groups and / or alkynyl groups, the amount of the one or more polydiorganosiloxanes being 30 wt.% to 70 wt.% of the composition;

[0021] (ii) fumed silica filler, the amount of the fumed silica filler being 28.0 wt.% to 40.0 wt.%, the fumed silica filler being replaceable in part by (iii) quartz having a particle size of 1 pm to 30 pm, wherein when quartz is present, the fumed silica and the quartz are each present in an amount of > 10 wt.% of the composition, the maximum combined amount of fumed silica and quartz present being 40 wt.% of the composition and:-

[0022] the total wt.% of fumed silica + half the wt.% of quartz is greater than or equal to (>) 28 wt.% of the composition;

[0023] (iv) a curing agent selected from the group consisting of:

[0024] (a) organic peroxides; or

[0025] (b) a hydrosilylation cure package comprising (b)(i) a hydrosilylation catalyst and (b)(ii) an organopolysiloxane crosslinker having at least three hydrogen groups per molecule; and

[0026] When the curing agent (iv) is (a) an organic peroxide, component (v), or when the curing agent (iv) is (b) a hydrosilylation cure package, optionally component (vi), wherein

[0027] (v) is a compound or complex of platinum metal or a platinum group metal; and

[0028] (vi) is a hydrosilylation curing inhibitor.

[0029] In one embodiment, the article is a battery module comprising a housing suitable for accommodating a plurality of battery cells and an insulating layer of a ceramic elastomeric silicone material for insulating adjacent battery cells, wherein, when present, the ceramic elastomeric silicone material is a cured product of the above-mentioned silicone rubber composition.

[0030] In another embodiment, the article is a battery module comprising a housing, a plurality of battery cells, and an insulating layer of a ceramic elastomeric silicone material sandwiched between adjacent battery cells, wherein the ceramic elastomeric silicone material is a cured product of the above-mentioned silicone rubber composition.

[0031] In further embodiments, the article is a battery pack comprising a plurality of battery modules as described above.

[0032] In another embodiment, a method for thermally insulating adjacent battery cells in an article designed to receive a plurality of battery cells by providing an insulating layer of a ceramizable elastomeric silicone material between the adjacent battery cells, the ceramizable elastomeric silicone material being the cured product of a silicone rubber composition comprising:

[0033] (i) one or more polydiorganosiloxanes having a weight average molecular weight of 200,000 g / mol to 800,000 g / mol, 0.01% to 1% alkenyl and / or alkynyl groups, the one or more polydiorganosiloxanes being present in an amount of 30 wt.% to 70 wt.% of the composition;

[0034] (ii) a fumed silica filler in an amount ranging from 28.0 wt.% to 40.0 wt.%, the fumed silica filler being partially replaceable by (iii) quartz having a particle size ranging from 1 μm to 30 μm, wherein when quartz is present, the fumed silica and the quartz are each present in an amount of ≥ 10 wt.% of the composition, the maximum total combined amount of fumed silica and quartz present being 40 wt.% of the composition and:

[0035] [Total wt.% of fumed silica] + [half of the wt.% of quartz] ≥ 28 wt.% of the composition;

[0036] (iv) a curing agent selected from the group consisting of:

[0037] (a) organic peroxides; or

[0038] (b) a hydrosilylation cure package comprising (b)(i) a hydrosilylation catalyst and (b)(ii) an organopolysiloxane crosslinker having at least three hydrogen groups per molecule; and

[0039] When the curing agent (iv) is (a) an organic peroxide, component (v), or when the curing agent (iv) is (b) a hydrosilylation cure package, optionally component (vi), wherein

[0040] (v) is a compound or complex of platinum metal or a platinum group metal; and

[0041] (vi) is a hydrosilylation curing inhibitor.

[0042] Further provided is the use of a ceramicizable elastomeric silicone material as a thermal insulation layer between adjacent battery cells in an article suitable for receiving a plurality of battery cells, wherein the ceramicizable elastomeric silicone material is a cured product of a silicone rubber composition comprising:

[0043] (i) one or more polydiorganosiloxanes having a weight average molecular weight of 200,000 g / mol to 800,000 g / mol, 0.01% to 1% alkenyl and / or alkynyl groups, the one or more polydiorganosiloxanes being present in an amount of 30 wt.% to 70 wt.% of the composition;

[0044] (ii) a fumed silica filler in an amount ranging from 28.0 wt.% to 40.0 wt.%, the fumed silica filler being partially replaceable by (iii) quartz having a particle size ranging from 1 μm to 30 μm, wherein when quartz is present, the fumed silica and the quartz are each present in an amount of ≥ 10 wt.% of the composition, the maximum total combined amount of fumed silica and quartz present being 40 wt.% of the composition and:

[0045] [Total wt.% of fumed silica] + [half of the wt.% of quartz] ≥ 28 wt.% of the composition;

[0046] (iv) a curing agent selected from the group consisting of:

[0047] (a) organic peroxides; or

[0048] (b) a hydrosilylation cure package comprising (b)(i) a hydrosilylation catalyst and (b)(ii) an organopolysiloxane crosslinker having at least three hydrogen groups per molecule; and

[0049] When the curing agent (iv) is (a) an organic peroxide, component (v), or when the curing agent (iv) is (b) a hydrosilylation cure package, optionally component (vi), wherein

[0050] (v) is a compound or complex of platinum metal or a platinum group metal; and

[0051] (vi) is a hydrosilylation curing inhibitor.

[0052] Further provided is the use of a ceramizable elastomeric silicone material as a thermal insulation layer between adjacent battery cells in a battery module, wherein the ceramizable elastomeric silicone material is a cured product of the silicone rubber composition as described above.

[0053] For the avoidance of doubt, it should be understood that in all other references to weight percent (wt.%) of a composition above and in this disclosure, the total wt.% of all compositions is in all cases 100%. The one or more battery cells in each battery module are preferably lithium-ion battery cells, the battery modules as described above are preferably lithium-ion battery modules, and a battery pack including one or more battery modules as described above is a lithium-ion battery pack.

[0054] When the article is a battery module, each battery module as described above is electrically interconnected with the other battery modules in the battery pack. The electrical interconnections may be in series or in parallel as required. Each battery module as described above comprises a housing containing a plurality of battery cells. A single battery cell in an article such as a battery module as described above may have any suitable shape, for example the battery cell may be prismatic, cylindrical or in the form of a pouch, but must be electrically connected to the other cells in the battery module. A thermal insulation layer between the battery cells in the article, such as a battery module, is provided between adjacent cells so that in the event of a failure, the thermal insulation layer will prevent excessive heat gain from being immediately transferred to other nearby / adjacent battery cells, wherein the side of the thermal insulation layer facing the failed cell tends to ceramicize due to the released heat and temperature increase. The side of the thermal insulation layer of the ceramicizable elastomeric silicone material facing away from the failed cell at least initially maintains the elastomer to protect the adjacent battery cells from the effects of the failed cell.

[0055] The thermal insulation layer of the ceramicizable elastomeric silicone material can be designed to accommodate any suitable shape of battery cell. For example, in the case of a prismatic battery, the thermal insulation layer can be sandwiched between adjacent batteries (as shown in this article). Figure 1 The battery module may be configured as a cross-hatched structure, with individual pockets provided for each battery cell. However, for other shapes, the insulation may be created to be wrapped around each individual cell, or the insulation may be created as a housing shaped to accommodate and thermally isolate an individual battery cell from its immediate neighbors, with each battery module including the same number of housings as battery cells.

[0056] Articles such as battery modules, as described above, need to provide mechanical and electrical interfaces with other battery modules and may also include, for example, cooling mechanisms, temperature monitors, voltage monitors, etc. Accordingly, the housing of a battery module, as described above, is sized and designed to accommodate a predetermined number of individual battery cells and, if desired, the aforementioned other systems. In one embodiment, the battery cells and battery modules are prismatic in shape.

[0057] The battery module housing can be made of any suitable material, such as metal or injection-molded plastic, and may also incorporate insert moldings where interconnect strips and terminals are molded into the plastic component. Small components and / or subassemblies can be enclosed in the housing by any suitable means, such as by overmolding, for storage and / or protection.

[0058] The housing of the battery module as described above (and / or the individual battery cells therein) may include a thinned area or burst panel. This provides a weakened area in the housing that is designed to prevent the internal pressure within the battery module or battery from exceeding a predetermined value. If the predetermined pressure value is reached due to a failure of one or more cells, the weakened or burst panel will be forced open and will allow gas to escape, thereby preventing further pressure buildup within the battery cell or associated battery module.

[0059] In one embodiment, provided herein is a battery pack comprising at least one battery module as described above, alternatively two or more battery modules as described above.

[0060] The design of a battery pack, such as an electric vehicle battery, is complex but incorporates a combination of several simple mechanical and electrical component systems that perform the basic required functions of the pack. Thus, a battery pack additionally includes one or more of the following:

[0061] (i) supporting electronics;

[0062] (ii) Heaters with their own control circuits (for extended lower operating temperatures or units);

[0063] (iii) cooler;

[0064] (iv) points and methods of fixing and interconnections;

[0065] (v) a control system for keeping the battery modules / cells within predefined specified operating ranges, e.g. for monitoring battery status and controlling energy flow, and protecting them from abuse;

[0066] (vi) a fuel measurement device for estimating state of charge (SOC); and / or

[0067] (vii) A communication system for communicating with other systems, such as other vehicle systems.

[0068] The battery pack as described above must fit into the space provided in the article for which it is to provide power, such as a vehicle. This may dictate the shape of the battery module and indeed the individual cells, and therefore the shape and / or form of the thermal insulation between adjacent battery cells in the battery module, as described herein. In some designs, the battery pack forms part of the housing of the final product. The color and texture of the battery pack housing must match the rest of the product. Such designs may require the incorporation of mechanical connection means to hold the battery pack in place. The mechanical connection means (e.g., latches) as well as electrical terminals and the like must interface with other components of the article to be powered by the battery pack. Any suitable material may be used for this purpose, for example, ABS polymer may be used.

[0069] The thermal insulation layer described above is designed to keep battery cell failures localized within the article, such as a battery module, and to provide a ceramic layer between adjacent batteries in the battery module in the event of a fire to prevent or at least delay the possibility of thermal runaway propagating within the entire article, such as a battery module, so as to provide safety protection in the event of thermal runaway of one battery cell in the battery module.

[0070] Therefore, when any of the battery cells in a battery module, such as an article described above, experiences abnormal heat release due to a short circuit, overcharging, or other reasons, thermal runaway in the associated cell can be isolated to prevent or delay the spread of thermal runaway to other cells in the battery module. Heat diffusion from a battery cell to adjacent cells can be effectively isolated by the thermal insulation layer. Furthermore, for some battery modules with a control circuit board housed within the battery module housing, the composite thermally conductive plate disclosed herein can be positioned between the battery and the circuit board, as well as between the battery and the connecting circuitry, thereby reducing battery heating caused by the circuit board and the circuitry.

[0071] As mentioned elsewhere, when a battery cell fails, the heat generated causes gas pressure to initially accumulate within the cell, but ultimately accumulate within it in the event of a cell rupture. Such pressure buildup can reach pressures equal to or greater than (≥) 0.9 MPa and is caused by accumulated heated gases (such as CO2, CO and H2) and / or liquids, such as electrolytes, generated by the failed cell and / or battery module. Analysis of failure modes and behavior of lithium-ion battery cells shows that in the event of thermal runaway of a battery cell, the temperature can rise, for example, to 595°C in 400 seconds, and in the case of a failed cell, a corresponding pressure buildup of, for example, 0.85 MPa, alternatively 0.9 MPa or even greater can be generated. It has been found that the current aerogel materials used can lose their structure under such pressures, whereas the thermal insulation layer designed to be ceramicized as described above at least partially retains its form and therefore remains thermally insulating. The rupture disc housed on top of the cell is designed to rupture when the pressure reaches a predetermined value, such as 0.85 MPa, alternatively 0.9 MPa, to produce the gas and / or liquid, such as the electrolyte released from the failed cell and the decomposed liquid electrolyte. Even so, although this will alleviate the pressure buildup, for example, the pressure will be reduced to a more manageable level, such as 0.3 MPa, the battery remains at an excessively high temperature and, if transferred to other cells in the battery module, may induce thermal runaway in the remaining cells in the battery module.

[0072] Using the thermal insulation layer as described above as a separator between adjacent battery cells avoids or delays thermal runaway to provide sufficient passenger evacuation time, to provide sufficient time for the driver and passengers to exit the vehicle, and the like.

[0073] The thermal insulation layer as described above is capable of being ceramicized, and it has been determined that if the thermal insulation layer in contact with a battery cell experiencing thermal runaway becomes ceramicized due to the resulting heat / fire, the portion of the thermal insulation layer away from the battery cell can remain unceramicized and have a sufficient thickness, for example ≥1.5 mm, thereby simultaneously slowing down heat transfer to adjacent cells.

[0074] The composition may include one or more optional additives, but the total weight % of the composition is 100 weight %.The alkenyl and / or alkynyl content of polymer (i) is determined using quantitative infrared analysis according to ASTM E168.

[0075] Component (i) of the silicone rubber composition herein is one or more polydiorganosiloxanes having a weight average molecular weight of 200,000 to 800,000 g / mol and 0.01% to 1% alkenyl and / or alkynyl groups as determined using quantitative infrared analysis according to ASTM E168, the one or more polydiorganosiloxanes being present in an amount of 30 wt.% to 70 wt.% of the composition.

[0076] The weight average molecular weight (Mw) (and number average molecular weight (Mn)) of silicones can also be determined by gel permeation chromatography (GPC). This technique is standard and yields values ​​for Mw (weight average molecular weight), Mn (number average molecular weight), and polydispersity index (PI) (where PI = Mw / Mn). The Mw values ​​provided in this application are determined by GPC and represent typical values.

[0077] The polydiorganosiloxane polymer has a plurality of units of formula (I):

[0078] R a SiO (4-a) / 2 (I)

[0079] Wherein each R is independently selected from aliphatic hydrocarbon groups, aromatic hydrocarbon groups or organic groups (i.e., any organic substituent group having one free valence at a carbon atom, regardless of the type of functional group). Saturated aliphatic hydrocarbon groups are exemplified by, but not limited to, alkyl groups (such as methyl, ethyl, propyl, pentyl, octyl, undecyl and octadecyl) and cycloalkyl groups (such as cyclohexyl). Unsaturated aliphatic hydrocarbon groups are exemplified by, but not limited to, alkenyl groups (such as vinyl, allyl, butenyl, pentenyl, cyclohexenyl and hexenyl); and alkynyl groups. Aromatic hydrocarbon groups are exemplified by, but not limited to, phenyl, tolyl, xylyl, benzyl, styryl and 2-phenylethyl. Examples of organic groups include, but are not limited to, halogenated alkyl groups, such as fluoroalkyl, chloromethyl, and 3-chloropropyl in the case of fluoroorganosilicon polymers discussed in detail below; nitrogen-containing groups (such as amino, amido, imino, and imino groups); oxygen-containing groups (such as polyoxyalkylene, carbonyl, alkoxy, and hydroxyl groups). Additional organic groups may include sulfur-containing, phosphorus-containing, and / or boron-containing groups. The subscript "a" may be 0, 1, 2, or 3, but is typically predominantly 2 or 3.

[0080] When R is a methyl group, the siloxy units can be described by the shorthand (abbreviated) nomenclature, i.e., "M," "D," "T," and "Q" (further teaching on silicone nomenclature can be found in Walter Noll, Chemistry and Technology of Silicones, 1962, Chapter 1, pp. 1-9). The M unit corresponds to a siloxy unit where a=3, i.e., R3SiO 1 / 2 ; The D unit corresponds to a siloxy unit where a=2, i.e. R2SiO 2 / 2 ; T unit corresponds to a siloxy unit where a=1, i.e. R1SiO 3 / 2 ; Q unit corresponds to a siloxy unit where a=0, i.e. SiO 4 / 2 .

[0081] Examples of typical groups on the polydiorganosiloxane polymer (i) include alkenyl groups, alkyl groups and / or aryl groups. These groups can be in the side chain position (on the D or T siloxy units) or at the end (on the M siloxy units). As previously mentioned, alkenyl and / or alkynyl groups are required. Suitable alkenyl and / or alkynyl groups in the polydiorganosiloxane polymer (i) generally contain 2 to 10 carbon atoms, for example, vinyl, isopropenyl, allyl and 5-hexenyl for alkenyl groups. Preferably, the alkenyl or alkynyl group is an alkenyl group, or a vinyl group.

[0082] The silicon-bonded organic groups attached to the polydiorganosiloxane polymer (i) other than the alkenyl and / or alkynyl groups are typically selected from the group consisting of monovalent saturated hydrocarbon groups typically containing from 1 to 10 carbon atoms, and monovalent aromatic hydrocarbon groups typically containing from 6 to 12 carbon atoms, which are unsubstituted or substituted by groups which do not interfere with the curing of the composition of the present application, such as halogen atoms. Preferred classes of silicon-bonded organic groups are, for example, alkyl groups such as methyl, ethyl and propyl groups; and aryl groups such as phenyl groups.

[0083] The molecular structure of the polydiorganosiloxane polymer (i) is typically linear, however, due to the presence of T units within the molecule (as previously described), some branching can be present.

[0084] As noted above, the polydiorganosiloxane having a weight average molecular weight of 200,000 g / mol to 800,000 g / mol has a viscosity of greater than 1,000,000 mPa.s, and is therefore a high viscosity gum.

[0085] The polydiorganosiloxane gum typically has a viscosity of at least 1,000,000 mPa.s at 25°C. However, as it is difficult to measure the viscosity of high viscosity fluids such as silicone rubber gum, the gum is often described by way of its Williams Plasticity value rather than by viscosity, in accordance with ASTM D-926-08. The polydiorganosiloxane gum (i) has a viscosity which results in a Williams Plasticity of at least 30 mm / 100, as measured in accordance with ASTM D-926-08, or at least 50 mm / 100, as measured in accordance with ASTM D-926-08, or at least 100 mm / 100, as measured in accordance with ASTM D-926-08, or 100 mm / 100 to 300 mm / 100, as measured.

[0086] The polydiorganosiloxane polymer (i) can be selected from polydimethylsiloxanes, alkylmethylpolysiloxanes, alkylarylpolysiloxanes or copolymers thereof containing, for example, alkenyl groups and / or alkynyl groups, and can have any suitable end groups, for example, they can be trialkyl terminated, alkenyl dialkyl terminated, or can be terminated with any other suitable combination of end groups, provided that each polymer contains at least two alkenyl or alkynyl groups (typically alkenyl groups) per molecule. Thus, by way of example, the polydiorganosiloxane polymer (i) can be dimethylvinyl terminated polydimethylsiloxane, dimethylvinylsiloxy terminated dimethylmethylphenylsiloxane, trialkyl terminated dimethylmethylvinyl polysiloxane or dialkylvinyl terminated dimethylmethylvinyl polysiloxane copolymer.

[0087] For example, the polydiorganosiloxane polymer (i) containing alkenyl or alkynyl groups at both terminals can be represented by the general formula (II):

[0088] R'R″R″′SiO-(R″R″′SiO) m -SiOR″′R″R' (II)

[0089] In formula (II), each R ' can be an alkenyl group or an alkynyl group, or an alkenyl group, which generally contains 2 to 10 carbon atoms. The alkenyl group includes but is not limited to vinyl, propenyl, butenyl, pentenyl, hexenyl, alkenylated cyclohexyl group, heptenyl, octenyl, nonenyl, decenyl or similar straight and branched alkenyl groups and alkenylated aromatic ring structures. The alkynyl group can be selected from but is not limited to ethynyl, propynyl, butynyl, pentynyl, hexynyl, alkynylated cyclohexyl group, heptenyl, octenyl, nonynyl, decynyl or similar straight and branched alkenyl groups and alkenylated aromatic ring structures.

[0090] R" does not contain ethylenically unsaturated groups, each R" may be the same or different and is each selected from: a monovalent saturated hydrocarbon group, which typically contains 1 to 10 carbon atoms, and a monovalent aromatic hydrocarbon group, which typically contains 6 to 12 carbon atoms. R" may be unsubstituted or substituted with one or more groups that do not interfere with the curing of the composition of the present invention, such as halogen atoms. Alternatively, R" contains 1 to 6 carbon atoms, alternatively, R" is methyl. R"' is R' or R".

[0091] In one embodiment, the polydiorganosiloxane present may be a mixture of component (i) as described above and a polydiorganosiloxane (i)(a) having a significantly higher alkenyl / alkynyl level than component (i), i.e., an alkenyl / alkynyl content of 7 to 9 wt.% of polymer (i)(a). Typically, the polydiorganosiloxane (i)(a) is a polydimethylmethylalkenylsiloxane having an alkenyl and / or alkynyl content vi of 6.00 to 10 wt.% of polymer (i)(a), alternatively 7.00 to 9.00 wt.% of polymer (i)(a). The alkenyl / alkynyl groups in polymer (i)(a) are typically all vinyl. Such polydimethylmethylalkenylsiloxanes may have three non-reactive end groups, for example, may be trialkyl terminated or may include vinyl end groups, for example, may be terminated dimethylvinyl. The cup / spindle method according to ASTM D1084 method B is used Spindle in the RV or LV range is most suitable for the viscosity range, the viscosity of such polymers may be significantly lower than the glue of (i) above, for example, it may have a viscosity of 10,000 mPa.s to 500,000 mPa.s at 25°C, alternatively 10,000 mPa.s to 150,000 mPa.s at 25°C, alternatively 10,000 mPa.s to 80,000 mPa.s at 25°C.

[0092] The polydiorganosiloxane polymer (i) is present in the composition as previously described herein in an amount from 30% to 75% by weight of the composition, alternatively from 30% to 70% by weight of the composition, alternatively from 30% to 65% by weight of the composition.

[0093] The polydiorganosiloxane polymer (i)(a) can have the same general chemical structure and / or viscosity as any of the structures described above for polydiorganosiloxane polymer (i), however, it must include a much greater amount of alkenyl or alkynyl groups, i.e., 7 to 9 wt.% alkenyl or alkynyl groups. The alkenyl and / or alkynyl content of polymer (i)(a) can also be determined using quantitative infrared analysis according to ASTM E168. Typically, the alkenyl or alkynyl group is an alkenyl group, an alkenyl group having 2 to 6 carbon atoms, or a vinyl group.

[0094] The polydiorganosiloxane polymer (i)(a) is an optional ingredient. When present in the composition, the polydiorganosiloxane polymer may be present in an amount up to a maximum of 15 wt. % of the composition, alternatively up to 12.5 wt. % of the composition.

[0095] The compositions herein may comprise fumed silica filler (ii) and optionally quartz filler (iii).

[0096] Fumed silica (ii)

[0097] Finely divided fumed silica, having a thickness of typically at least 50 m 2 / g relatively high surface area. Usually, a surface area of ​​100 m2 is used as measured according to the BET method. 2 / g to 595m 2 / g, alternatively 100m 2 / g to 500m 2 / g (using the BET method according to ISO 9277:2010), alternatively 100m 2 / g to 400m 2 / g (using the BET method according to ISO 9277:2010), alternatively 150m 2 / g to 400m 2 / g (using the BET method according to ISO 9277:2010) of fumed silica.

[0098] The amount of finely divided fumed silica (ii) used in the compositions described herein is typically present in an amount of 28 to 40 wt. % of the composition; alternatively, in the absence of quartz, 28 to 36 wt. % of the composition.

[0099] When the fumed silica (ii) is naturally hydrophilic (e.g., untreated fumed silica filler), the reinforcing filler is typically treated with a treating agent to render it hydrophobic, so as to be more easily incorporated into the polymer (i) and (i)(a) when the latter is present. The fumed silica can be treated prior to introduction into the composition or in situ (i.e., by mixing together the components in the presence of at least a portion of the other components of the composition of the present application until fully treated and uniformly dispersed as a homogeneous material). Typically, the untreated fumed silica (ii) is treated in situ with a treating agent in the presence of at least one of the polydiorganosiloxane polymer (i) or (i)(a) when the latter is present. The fumed silica is provided to ensure the necessary mechanical strength and also to rapidly generate a ceramic-like layer for thermal insulation under high temperature and high pressure failure conditions.

[0100] The treating agent for treating the fumed silica (ii) can be selected from one or more of, for example, organosilanes, polydiorganosiloxanes or organosilazanes, hexaalkyldisilazanes, short chain siloxane diols, fatty acids or fatty acid esters such as stearates, to render one or more of the fillers hydrophobic and thus more easily handled and obtain a homogeneous mixture with the other components. Specific examples include, but are not limited to, liquid hydroxy-terminated polydiorganosiloxanes containing an average of 2 to 20 diorganosiloxane repeat units per molecule, which can optionally include fluorine groups and / or fluorine-containing groups if desired, hexaorganodisiloxanes, hexaorganodisilazanes, and the like. A small amount of water can be added along with the silica treating agent as a processing aid. The surface treatment of the fumed silica renders them easily wetted by the polymer (i) and (i)(a) if the latter is present. These surface-modified fumed silicas do not cake and can be uniformly incorporated into the polymer (i) and (i)(a) to improve the rheological behavior, such as lower viscosity and viscosity stability during storage of the uncured composition and improved room temperature mechanical properties of the cured composition.

[0101] In a preferred embodiment, the filler treating agent is a low molecular weight organosilicon compound disclosed in the art as suitable for preventing wrinkling of organosiloxane compositions during processing.

[0102] Component (iii) is quartz, a non-reinforcing type of silica, and has a particle size of between 1 pm to 30 pm. Quartz can be added to at least partially replace some of the fumed silica. When present, both the fumed silica and the quartz are present in amounts of > 10 wt% of the composition, with the maximum combined amount of fumed silica and quartz present being 40 wt% of the composition, and further requiring that:

[0103] [Total wt.% of fumed silica] + [half of the wt.% of quartz] ≥ 28 wt.% of the composition.

[0104] The above requirements are to provide suitable mechanical strength and also the ability to quickly form a ceramic layer for thermal insulation under high temperature and high pressure failure conditions.If desired, the calcium silicate, such as wollastonite, may be hydrophobized, but this is not required.

[0105] Peroxide catalyst (iv) (a)

[0106] The compositions as described herein may be cured using an organic peroxide catalyst (iv)(a) or a mixture of different types of organic peroxide catalysts.

[0107] The organic peroxide catalyst can be any of the well-known commercial organic peroxides used to cure silicone rubber compositions. The amount of organic peroxide used is determined by the nature of the curing process, the organic peroxide used, and the composition used. Typically, the amount of organic peroxide catalyst used in the composition as described herein is from 0.2 wt.% to 3 wt.%, alternatively from 0.2 wt.% to 2 wt.%, based on the weight of the composition in each case.

[0108] Suitable organic peroxides are substituted or unsubstituted dialkyl peroxides, alkylaroyl peroxides, diaroyl peroxides, for example benzoyl peroxide and 2,4-dichlorobenzoyl peroxide, di-tert-butyl peroxide, dicumyl peroxide, tert-butylcumyl peroxide, bis(tert-butylperoxyisopropyl)benzene, bis(tert-butylperoxy)-2,5-dimethylhexyne, 2,4-dimethyl-2,5-di(tert-butylperoxy)hexane, di-tert-butyl peroxide and 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane.

[0109] Alternatively, the curing agent may be (iv)(b) a hydrosilylation cure package comprising (i) a hydrosilylation catalyst and (ii) an organopolysiloxane crosslinker having at least three hydrogen groups per molecule.

[0110] (iv)(b)(i) Hydrosilylation catalyst

[0111] When component (iv)(b)(i) is present, the hydrosilylation catalyst is preferably one of the platinum group metals (platinum, ruthenium, osmium, rhodium, iridium and palladium) or a compound of one or more of such metals. Platinum and platinum compounds are preferred because these catalysts have a high level of activity in the hydrosilylation reaction.

[0112] Examples of preferred hydrosilylation catalysts (iv)(b)(i) include, but are not limited to, platinum black, platinum on various solid supports, chloroplatinic acid, alcoholic solutions of chloroplatinic acid, and complexes of chloroplatinic acid with ethylenically unsaturated compounds such as olefins and organosiloxanes containing silicon-bonded ethylenically unsaturated hydrocarbon groups. Catalyst (iv)(b)(i) may be platinum metal, platinum metal, or a compound or complex of a platinum group metal deposited on a support such as silica gel or powdered charcoal.

[0113] Examples of suitable platinum-based catalysts include

[0114] (i) Complexes of chloroplatinic acid with organosiloxanes containing ethylenically unsaturated hydrocarbon groups as described in US Pat. No. 3,419,593;

[0115] (ii) chloroplatinic acid in hexahydrate or anhydrous form;

[0116] (iii) a platinum-containing catalyst obtained by a process comprising the steps of reacting chloroplatinic acid with an aliphatically unsaturated organosilicon compound such as divinyltetramethyldisiloxane;

[0117] (iv) olefin-platinum-silyl complexes such as (COD)Pt(SiMeCl2)2 as described in U.S. Patent No. 6,605,734, wherein "COD" is 1,5-cyclooctadiene; and / or

[0118] (v) Karstedt catalysts, platinum divinyltetramethyldisiloxane complexes containing typically about 1 wt% platinum in a solvent such as toluene, may be used. These are described in US Pat. Nos. 3,715,334 and 3,814,730.

[0119] When present, the hydrosilylation catalyst (iv)(b)(i) is present in a catalytic amount in the total composition, i.e., an amount or quantity sufficient to catalyze the addition / hydrosilylation reaction and cure the composition into an elastomeric material under the desired conditions. Different levels of hydrosilylation catalyst (iv)(b)(i) can be used to tailor the reaction rate and cure kinetics. The catalytic amount of hydrosilylation catalyst (iv)(b)(i) is typically between 0.01 ppm and 10,000 parts by weight of platinum group metal per million (ppm), based on the combined weight of the composition polymers (i) and (ii)(a), filler (ii), and optionally filler (iii); alternatively, between 0.01 ppm and 5000 ppm; alternatively, between 0.01 ppm and 3,000 ppm; and alternatively, between 0.01 ppm and 1,000 ppm. In specific embodiments, the catalytic amount of the catalyst may be in the range of 0.01 ppm to 1,000 ppm, or 0.01 ppm to 750 ppm, or 0.01 ppm to 500 ppm, and or 0.01 ppm to 100 ppm metal, based on the weight of the composition. This range may relate only to the metal content in the catalyst or to the entire catalyst as detailed (including its ligands), but typically these ranges relate only to the metal content in the catalyst. The catalyst may be added as a single substance or as a mixture of two or more different substances. Typically, the catalyst will be present in an amount in the range of 0.001% to 3.0% by weight of the composition, depending on the form / concentration in which the catalyst package is provided.

[0120] (iv)(b)(ii) Organohydrogenpolysiloxane

[0121] Component (iv)(b)(ii) is an organohydrogenpolysiloxane that acts as a crosslinker for curing polymers (i) and (ii) by reacting the silicon-bonded hydrogen atoms in component (iv)(b)(ii) with the alkenyl groups in polymers (i) and (ii) catalyzed by component (iv)(b)(i) as described below. Component (iv)(b)(ii) typically contains three or more silicon-bonded hydrogen atoms so that the hydrogen atoms can react with the unsaturated alkenyl or alkynyl groups of polymers (i) and (ii) to form a network structure and thereby cure the polymers. When polymers (i) and (ii) have >2 alkenyl or alkynyl groups per molecule, some or all of the organohydrogenpolysiloxane (iv)(b)(ii) may alternatively have two silicon-bonded hydrogen atoms per molecule.

[0122] The molecular configuration of component (iv)(b)(ii) is not particularly limited, and it may be linear, branched linear, or cyclic. Although the molecular weight of this component is not particularly limited, the cup / spindle method according to ASTM D 1084 Method B is used. The most suitable spindles are in the RV or LV range for the viscosity range, typically from 0.001 Pa.s to 50 Pa.s at 25°C, to obtain good miscibility with polymers (i) and (ii).

[0123] Component (iv)(b)(ii) is typically added in an amount such that the molar ratio of the total number of silicon-bonded hydrogen atoms in component (iv)(b)(ii) to the total number of alkenyl groups in polymers (i) and (ii) is from 0.5:1 to 20:1. When this ratio is less than 0.5:1, a well-cured composition is not obtained. When this ratio exceeds 20:1, there is a tendency for the hardness of the cured composition to increase when heated.

[0124] Examples of component (iv)(b)(ii) include, but are not limited to:

[0125] (i) trimethylsiloxy-terminated methylhydrogenpolysiloxane,

[0126] (ii) trimethylsiloxy-terminated polydimethylsiloxane-methylhydrogensiloxane,

[0127] (iii) a dimethylsiloxane-methylhydrogensiloxane copolymer terminated with dimethylhydrogensiloxy groups,

[0128] (iv) dimethylsiloxane-methylhydrogensiloxane cyclic copolymer,

[0129] (v) (CH3)2HSiO 1 / 2 unit and SiO 4 / 2 The copolymer composed of units,

[0130] (vi) (CH3)3SiO 1 / 2 Unit, (CH3)2HSiO 1 / 2 unit and SiO 4 / 2 units, and

[0131] As described above, (CH3)2HSiO 1 / 2 Unit and (R 2 Z) d (R 3 ) e SiO (4-d-e) / 2 Alternatively, component (iv)(b)(ii) may be a filler, such as silica treated with one of the above.

[0132] The silicon-bonded hydrogen (Si-H) content of a polymer is determined using quantitative infrared analysis according to ASTM E168. In this context, the ratio of silicon-bonded hydrogen to alkenyl (vinyl) groups is important when relying on a hydrosilylation cure process. Generally, this is determined by calculating the total weight percent of alkenyl groups (e.g., vinyl groups) [V] in the composition and the total weight percent of silicon-bonded hydrogen [H] in the composition, and assuming a molecular weight of hydrogen of 1 and a molecular weight of vinyl of 27, the molar ratio of silicon-bonded hydrogen to vinyl groups is 27 [H] / [V].

[0133] As previously indicated, when the curing agent (iv) is (a) an organic peroxide, a compound or complex of platinum metal or a platinum group metal (v) is provided in the composition. It should be noted that in these cases, the component (v) does not participate in the curing process because it is provided in the absence of an organohydrogenpolysiloxane and therefore cannot undergo a hydrosilylation cure process. Component (v) can be any of the platinum species indicated above in (iv)(b)(i) and is provided in the same amount as in (iv)(b)(i) above.

[0134] When the composition as described above solidifies by addition / hydrosilylation reaction component (vi), an inhibitor can be utilized to suppress the solidification of the composition. These inhibitors are used to prevent the premature solidification in storage and / or obtain the long working time or the pot life of the composition of the hydrosilylation curing by delaying or suppressing the activity of the catalyst. The inhibitor of the hydrosilylation catalyst, for example, a platinum metal-based catalyst, is well known in the art and can include hydrazine, triazole, phosphine, mercaptan, organic nitrogen compound, alkynol, methane silylation alkynol, maleate, fumarate, ethylenic or aromatic unsaturated amides, ethylenic unsaturated isocyanate, olefinic siloxane, unsaturated hydrocarbon monoesters and diesters, conjugated alkene-alkynes, hydroperoxide, nitrile and two aziridines.

[0135] One class of known platinum catalyst inhibitors includes the acetylenic compounds disclosed in US Pat. No. 3,445,420. Alkynols such as 2-methyl-3-butyn-2-ol constitute a preferred class of inhibitors that will inhibit the activity of platinum-containing catalysts at 25°C. Compositions containing these inhibitors typically require heating at temperatures of 70°C or above in order to cure at an achievable rate.

[0136] Examples of alkynols and their derivatives include 1-ethynyl-1-cyclohexanol (ETCH), 2-methyl-3-butyn-2-ol, 3-butyn-1-ol, 3-butyn-2-ol, propargyl alcohol, 2-phenyl-2-propyn-1-ol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynylcyclopentanol, 1-phenyl-2-propynol, 3-methyl-1-pentene-4-yn-3-ol, and mixtures thereof.

[0137] When present, inhibitor concentrations as low as 1 mole of inhibitor per mole of metal of catalyst (iv)(b)(i) will in some cases impart satisfactory storage stability and cure rates. In other cases, inhibitor concentrations of up to 500 moles of inhibitor per mole of metal of catalyst (iv)(b)(i) may be required. The optimal concentration of a given inhibitor in each composition is readily determined by routine experimentation. Depending on the concentration and form in which the selected inhibitor is provided / commercially available, the inhibitor, when present in the composition, is typically present in an amount of 0.0125% to 10% by weight of the composition. Mixtures of the above may also be used.

[0138] When component (iv)(b) is relied upon to cure the composition, the composition will typically be stored in two parts, typically referred to as Part A and Part B, with the goal of separating components (iv)(b)(ii) and (iv)(b)(i) prior to curing to avoid premature curing, as discussed further below. Such two-part compositions are constructed to enable easy mixing immediately prior to use, and typically have a weight ratio of Part A:Part B of 15:1 to 1:1. Furthermore, when component (vi) a cure inhibitor is present, it is typically stored in the same part.

[0139] Additional optional components

[0140] Depending on its intended use, additional optional components may be present in the silicone rubber composition. Examples of such optional components include pot life extenders, flame retardants, lubricants, non-reinforcing fillers, pigments, and mixtures thereof.

[0141] Additional examples of additives include mold release agents, UV light stabilizers, biocides, heat stabilizers, compression set improving additives, and mixtures thereof.

[0142] Examples of flame retardants include aluminum trihydrate, chlorinated paraffin, hexabromocyclododecane, triphenyl phosphate, dimethyl methylphosphonate, tris(2,3-dibromopropyl)(tris)bromide) phosphate, and mixtures or derivatives thereof.

[0143] Examples of pigments include, but are not limited to, titanium dioxide, chromium oxide, bismuth vanadium oxide, iron oxide, and mixtures thereof.

[0144] Examples of heat stabilizers include metal compounds such as red iron oxide, yellow iron oxide, iron hydroxide, cerium oxide, cerium hydroxide, lanthanum oxide, copper phthalocyanine, aluminum hydroxide, fumed titanium dioxide, iron naphthenate, cerium naphthenate, cerium dimethylpolysilanolate, and acetylacetonates of metals selected from copper, zinc, aluminum, iron, cerium, zirconium, titanium, and the like. The amount of heat stabilizer present in the composition may range from 0.01% to 10% by weight of the total composition.

[0145] Further examples of additives include release agents, UV light stabilizers, biocides, heat stabilizers, compression set improving additives and mixtures thereof. When present, the calcium silicate used may have a maximum average particle size of 1 μm to 30 μm. Any form of calcium silicate that is capable of forming a char in the presence of a fire may be used. This may include calcium metasilicate, also known as wollastonite. Wollastonite is a naturally occurring mineral that can be provided in a variety of forms, for example wollastonite can be provided in acicular form, i.e. in a needle-like shape. Typically, the aspect ratio, i.e. the ratio of the length of the particle to its diameter, is at least 2:1. Wollastonite preferably has an average particle size of about 2 μm to 15 μm and an aspect ratio of about 2:1 or greater, most preferably a particle size of about 2 μm and an aspect ratio of about 2:1. The wollastonite used in the present invention has a low BET surface area, typically less than 25 m 2 / g (using the BET method according to ISO 9277:2010). Calcium silicates, such as wollastonite, may be hydrophobically treated, but this is not necessary.

[0146] As discussed above, when cured by hydrosilylation, the composition will be stored in two parts before use: part A and part B. Typically, part A will contain some of component (i) the polymer, component (ii) the fumed silica and, optionally, some of the quartz (iii) and hydrosilylation catalyst (iv)(b)(i), and part B will contain the remainder of components (i)(ii) and (iii) as well as silicon-bonded hydrogen (Si-H) including the crosslinker (iv)(b)(ii) and (vi) the inhibitor (when present). The two-part composition can be designed to be mixed together in any suitable ratio, for example, so as to enable easy mixing immediately prior to use, and the weight ratio of part A:part B is typically 15:1 to 1:1. In such cases, the part A and part B compositions are prepared separately and mixed together only shortly before use. In each case, the silicone base comprising the polymer (i) and filler (ii) and, optionally, (iii) can be prepared before the other ingredients are introduced into the respective parts. When desired, a hydrophobic treatment agent may be added during the preparation of the base to enable in situ treatment of the filler.

[0147] When using peroxide curing agent to make composition solidification, as described above composition as desired under ambient temperature or elevated temperature all components are prepared.In either case, any suitable mixing technique and device described in the prior art can be used.To be determined according to the viscosity of component for mixing all ingredients or the specific device of combination part A and part B.Although it should be noted that, because polymer is normally silicone glue, it may be necessary to use a mixing device that can mix glue.Suitable mixer includes but is not limited to paddle mixer and kneader type mixer.Cooling each component during mixing may be desirable, to avoid composition from solidifying prematurely.

[0148] Also provided is a method for producing the aforementioned ceramizable elastomeric silicone material from a silicone rubber composition by mixing the components of the composition as described herein. The mixing step may involve, when the composition is in two parts, mixing the two parts together in the presence of a peroxide curing agent to combine all of the individual components. When the composition is in two or more parts, the parts may be mixed together in a suitable multi-part mixing system prior to curing.

[0149] Depending on viscosity and application, etc., the silicone rubber composition can be further processed by injection molding, encapsulation molding, compression molding, dispenser molding, extrusion molding, transfer molding, press vulcanization, centrifugal casting, calendaring, bead application, or blow molding.

[0150] The curing of the silicone rubber composition can be carried out as required by the type of curing package used. Typical curing temperatures may range from 80°C to 200°C, or from 100°C to 170°C. The resulting elastomeric material can be post-cured at a suitable temperature for a suitable period of time, for example, at a temperature of about 200°C, in each case for 2 hours to 10 hours, alternatively for 4 hours to 10 hours.

[0151] Curing can occur, for example, in a mold to form a molded silicone article.For example, the composition can be injection molded to form an article, or the composition can be overmolded by injection molding around an article or onto a substrate.

[0152] Preferably, in any of the embodiments described above, the Shore A hardness is ≥ 60 when post-cured according to ASTM D2240-15.

[0153] The insulation layer can be of any suitable thickness, but is designed so that its side facing the failed battery cell ceramicizes in the event of a sudden, large temperature increase, while the other side of the insulation layer is preferably not ceramicized and remains elastomeric. The thickness of the insulation layer can be 0.2 mm to 4.0 cm. Taking into account the available space and the number of cells required in the battery module, thicker layers are considered too thick for practical use. For the purposes of this article, an insulation layer of <0.2 mm is understood to be too thin to provide adequate insulation.

[0154] The battery module may further include:

[0155] a control circuit board disposed within the battery module housing; and

[0156] The thermal insulation layer may be at least partially disposed between the control circuit board and the one or more battery cells.

[0157] A battery module as described herein may additionally provide electrical or electronic circuitry within the battery module housing; and

[0158] Articles such as battery modules as described herein are designed to prevent or delay thermal runaway in the battery modules.

[0159] As mentioned previously, there is also provided

[0160] Use of a ceramicizable elastomeric silicone material as a thermal insulation layer between adjacent battery cells in an article suitable for receiving a plurality of battery cells, wherein the ceramicizable elastomeric silicone material is a cured product of a silicone rubber composition comprising:

[0161] (i) one or more polydiorganosiloxanes having a weight average molecular weight of 200,000 g / mol to 800,000 g / mol, 0.01% to 1% alkenyl and / or alkynyl groups, the one or more polydiorganosiloxanes being present in an amount of 30 wt.% to 70 wt.% of the composition;

[0162] (ii) a fumed silica filler in an amount ranging from 28.0 wt.% to 40.0 wt.%, the fumed silica filler being partially replaceable by (iii) quartz having a particle size ranging from 1 μm to 30 μm, wherein when quartz is present, the fumed silica and the quartz are each present in an amount of ≥ 10 wt.% of the composition, the maximum total combined amount of fumed silica and quartz present being 40 wt.% of the composition and:

[0163] [Total wt.% of fumed silica] + [half of the wt.% of quartz] ≥ 28 wt.% of the composition;

[0164] (iv) a curing agent selected from the group consisting of:

[0165] (a) organic peroxides; or

[0166] (b) a hydrosilylation cure package comprising (b)(i) a hydrosilylation catalyst and (b)(ii) an organopolysiloxane crosslinker having at least three hydrogen groups per molecule; and

[0167] When the curing agent (iv) is (a) an organic peroxide, component (v), or when the curing agent (iv) is (b) a hydrosilylation cure package, optionally component (vi), wherein

[0168] (v) is a compound or complex of platinum metal or a platinum group metal; and

[0169] (vi) is a hydrosilylation curing inhibitor.

[0170] The articles described herein are suitable for use in a variety of applications, such as electric vehicle battery (EVB) power supplies for electric and hybrid (electric and gasoline / diesel) driven vehicles, i.e., battery packs / systems used to power the propulsion systems of electric and hybrid vehicles, and are therefore designed to provide power for sustained periods of time. As previously discussed, the battery pack stores electricity that the motor uses to drive the vehicle's wheels. In the case of a hybrid electric vehicle, the propulsion system is powered by a battery pack much like that described above, but an internal combustion engine is also present, so the hybrid vehicle runs on electricity until the battery is depleted, and then switches to a carbon-based fuel to power the internal combustion engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0171] The accompanying drawings are included to provide a further understanding and illustrate exemplary embodiments and together with the detailed description serve to enhance understanding of the disclosure herein. For ease of explanation, Figure 1 is a representation of a battery module using prismatic cells as described herein.

[0172] FIG. 2 a is a photograph of the ceramicized side of a thermal insulation layer as described herein after testing.

[0173] FIG. 2 b is a photograph of the non-ceramic side of a thermal insulation layer as described herein after testing, showing that the non-ceramic side still possesses its elastomeric properties.

[0174] exist Figure 1 In the embodiment, a series of prismatic battery cells (1a–1h) are provided, such as lithium-ion battery cells in a battery module whose housing is not shown. Such battery modules can be used in power supplies for driving electric vehicles and hybrid electric vehicles, etc. as discussed above. Adjacent battery cells (1a-h) sandwich corresponding thermal insulation layers (2a-g). Although not shown, it will be understood that each battery includes an anode, a cathode and an electrolyte, and can be any suitable battery cell. Cell end plates (3) are provided at each end of the rows of alternating battery cells (1a-h) and thermal insulation layers (2a-g). Although Figure 1 Not shown, but depicted, the alternating prismatic battery cells (1a-h) and insulation layers (2a-g) remain within the battery module housing. The positive electrode terminal is identified as Figure 1 (4) in. The battery cells (1a-h) are electrically connected in series and / or in parallel, respectively, as required for the final purpose, wherein the positive terminal is electrically connected to the positive plate via the positive current collector, and the negative terminal is electrically connected to the negative plate via the negative current collector. By providing a thermal insulation layer (2a-g) between adjacent battery cells, a user of an article is powered or partially powered, such as a vehicle provided with a battery module designed to prevent thermal runaway propagation throughout the battery cells in the battery module using the thermal insulation layer (2a-g).

[0175] In use, if, for example, battery cell (1d) is faulty and enters or approaches thermal runaway, the thermal insulation layers (2c) and (2d) partially ceramicize the battery cells (1c) and (1e) and isolate them from the sharp increase in temperature in battery cell (1d) and delay or prevent the propagation of the thermal runaway phenomenon within the battery module.

[0176] FIG. 2 a is a photograph of the ceramicized side of the thermal insulation specimen used in the Examples, and FIG. 2 b shows the elastomeric surface of the side facing away from heating, which is still elastomeric in appearance.

[0177] The following examples illustrating compositions and components of the compositions, elastomers, and methods are intended to illustrate, not to limit, the invention. Example

[0178] A series of examples (Example 1-Example 7) and comparative examples (C.1-C.4) were prepared by mixing all the components in the composition detailed below. A silicone base was initially prepared according to Table 1 and then used as indicated to prepare the compositions in Table 2a and Table 4a.

[0179] Unless otherwise indicated, Mw was determined using gel permeation chromatography (GPC) according to ASTM D 1084 Method B, cup / spindle method using The spindle best suited for the viscosity range was either RV or LV range, all viscosities were measured at 25° C. The alkenyl and / or alkynyl and / or silicon-bonded hydrogen (Si—H) content of the components was determined using quantitative infrared analysis according to ASTM E168.

[0180] Fillers and filler treatment agents are first mixed with silicone polymer adhesive and evenly dispersed into the silicone polymer adhesive to form a silicone rubber base. When using an organic peroxide catalyst, the remaining components are then added and dispersed into the corresponding base, and the final composition is press-cured at an appropriate temperature for 10 minutes. In the case of compositions containing 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (DHBP) catalyst, the curing temperature used is 170°C. In the case of compositions containing bis(2,4-dichlorobenzoyl)peroxide catalyst, the curing temperature used is 120°C, and the platinum-cured composition is also cured at 120°C for 10 minutes. Some samples are post-cured at 200°C for 8 hours. When using hydrosilylation curing, the composition is prepared in two parts and then mixed together in a predetermined ratio shortly before use.

[0181] Table 1: Silicone rubber base materials used in the examples

[0182]

[0183] The compositions used in the examples are provided in Table 2a.

[0184] Table 2a: Composition of Examples

[0185]

[0186] In the table above

[0187] The Pt solution is a polydimethylsiloxane solution containing a platinum catalyst having about 5000 ppm of platinum metal relative to the remainder of the composition;

[0188] The cerium hydroxide masterbatch was a 50:50 (by weight) masterbatch of cerium hydroxide in a polydimethylsiloxane polymer having an Mw of 500,000 g / mol';

[0189] DCBP masterbatch is a 50:50 (by weight) masterbatch of bis(2,4-dichlorobenzoyl) peroxide catalyst in polydimethylsiloxane polymer;

[0190] DHBP masterbatch is a 50:50 (by weight) masterbatch of 40% polydimethylsiloxane polymer and 10% 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane catalyst in silica;

[0191] The quartz used was 5 μm obtained from US Silica.

[0192] The Si—H crosslinking agent is 83 wt % of a Si—H containing silicone resin having 6400 ppm Si—H bonds and 17 wt % of silica, wherein the silica serves as a carrier; and

[0193] The inhibitor masterbatch consisted of 4.8 wt% ethynyl-1-cyclohexanol (ETCH) in a silicone rubber masterbatch.

[0194] Table 2b: Quantities of the individual ingredients in Table 2a introduced as part of the rubber base A, B or C .

[0195]

[0196] The physical property results for the corresponding compositions / elastomers are shown in Tables 3a and 3b for the Examples together with the test methods used.

[0197] Table 3a - Physical property results of examples

[0198]

[0199] Thermal insulation test procedures and conditions :

[0200] The thermal tests were conducted on a 0.5 Mton hydraulic press supplied by Zhejiang Taizhou Mingen Hydraulic Equipment Fabrication Co. The press has a heated bottom plate, an aluminum sample plate, and a hydraulically driven top plate.

[0201] Test specimens were prepared with dimensions of 8 cm long, 4 cm wide and approximately 2 mm thick and had a 0.1092 m 2 total surface area.

[0202] Each test specimen is mounted on the center of an aluminum sample plate. The surface area of ​​the specimen in direct contact with the heated base plate is 0.0032 m 2 Using a 10kg steel load, this equates to a pressure of 0.0306MPa after removal of the hydraulic pressure.

[0203] The thermal insulation test was carried out at 595°C and at 500°C. For the 595°C test, the sample was heated at 595°C for 20 minutes, with the first 7 minutes at a pressure of approximately 0.9MPa and the remaining 13 minutes at a pressure of approximately 0.03MPa, as described above. The heated bottom plate of the press was first heated to approximately 595°C (or 500°C, depending on the selected test), and once this temperature was reached, the temperature of the heated plate was stabilized at 595°C. The specimen was then placed on the hot plate, and an aluminum plate was placed on top of the sample, sandwiching the sample between the heated bottom plate and the aluminum plate. A 10kg steel load plate was immediately placed on the aluminum plate, and a hydraulic press was used to apply a 0.87MPa pressure to start the test. After 420 seconds, the hydraulic pressure was removed, but the 10kg steel load was maintained on top of the aluminum plate to maintain a 0.03MPa pressure on the sample for the remaining 780 seconds of the test period. Both the hot stage temperature and the test specimen backside temperature were recorded during the test.After a total time of 1200 seconds, the test was stopped and the steel load and aluminum plate were removed from the hot stage.

[0204] The temperatures of the directly heated surface and back surface of the insulation layer samples were measured and compared using a WRNK-191 0.5*350mm thermocouple from Taizhou Cesmooy.

[0205] Table 3b: Thermal insulation test results of examples

[0206]

[0207] The compositions used in the examples are provided in Table 4a.

[0208] Table 4a: Composition of Comparative Examples

[0209] Element Comparative Example 1 Comparative Example 2 Comparative Example 3 Base A 82.20 98.00 Base B 98.00 Quartz, 5μm 15.8 Cerium Hydroxide MB 1.00 1.00 1.00 DHBP MB 1.00 1.00 1.00 Coated aerogel 100.00 100.00 100.00

[0210] The cerium hydroxide masterbatch and the DHBP masterbatch were the same as described above.

[0211] Table 4b: Amounts of ingredients included in the base

[0212]

[0213] The physical property results for the corresponding compositions / elastomers are shown in Tables 5a and 5b for the comparatives, along with the test methods used.

[0214] Table 5a: Physical tests of comparative examples

[0215] test Comparative Example 1 Comparative Example 2 Comparative Example 3 Shore A hardness tester (ASTM D2240-15) 51 59 41 Specific gravity (ASTM D792–00) 1.1437 1.247 1.096

[0216] Table 5b: Thermal insulation test results of comparative examples

[0217] Comparative Example 1 Comparative Example 2 Comparative Example 3 Hot surface temperature after heating at 595℃(℃) 595 595 595 Back surface temperature after heating at 595℃(℃) 430.8 388.6 454.8 Hot surface temperature after heating at 500℃(℃) 500 Back surface temperature after heating at 500℃(℃) 321.8

[0218] This example provides significantly improved backplate temperatures compared to the comparative example. It should also be noted that during the heating test, the side of the sample facing the heating plate experienced at least partial ceramicization, while the side facing away from the heating plate gave much lower temperature values ​​and visually appeared elastomeric. Furthermore, the temperature of the equivalent distal end face from the heating plate was significantly lower than that of the comparative example. These results are also believed to be improved compared to commercially available coated aerogel products.

[0219] Thus, the thermal insulation layer described above using the specified fumed silica (amorphous SiO2) or fumed silica (amorphous SiO2) + quartz (crystalline SiO2) loadings can rapidly produce a ceramic-like layer on the hot face under high temperature (595°C) and high pressure (0.9 MPa) test conditions, while the distal end temperature can be maintained lower than that of the comparative examples and the currently used aerogel felt materials (180°C to 240°C vs. 260°C to 450°C) and can maintain an elastomeric appearance. It should also be noted that, unlike commercially available coated aerogel materials, the thermal insulation layer described herein is essentially dust-free, and therefore does not require the same level of protective equipment as would be required when using the commercially available coated aerogel materials.

Claims

1. A battery module comprising a housing, a plurality of battery cells, and an insulation layer of a ceramic elastomeric silicone material sandwiched between adjacent battery cells, the insulation layer providing thermal insulation between adjacent battery cells, the ceramic elastomeric silicone material being a cured product of a silicone rubber composition comprising: (i) one or more polydiorganosiloxanes having a weight average molecular weight of 200,000 g / mol to 800,000 g / mol, 0.01% to 1% alkenyl and / or alkynyl groups, the one or more polydiorganosiloxanes being present in an amount of 30 wt.% to 70 wt.% of the composition; (ii) a fumed silica filler, wherein the amount of the fumed silica filler is 28.0 wt.% to 40.0 wt.%; (iv) a curing agent selected from the group consisting of: (a) organic peroxides; or (b) a hydrosilylation cure package comprising (b)(i) a hydrosilylation catalyst and (b)(ii) an organopolysiloxane crosslinker having at least three hydrogen groups per molecule; and component (v) when curing agent (iv) is (a) an organic peroxide, or optionally component (vi) when curing agent (iv) is (b) a hydrosilylation cure package, wherein (v) is a compound or complex of platinum metal or a platinum group metal; and (vi) is a hydrosilylation cure inhibitor; wherein the fumed silica filler (ii) is partially replaced by (iii) quartz having a particle size of 1 μm to 30 μm, wherein the fumed silica and the quartz are each present in an amount of ≥ 10 wt. % of the composition, the maximum total combined amount of fumed silica and quartz present being 40 wt. % of the composition and: [Total wt.% of fumed silica] + [half of the wt.% of quartz] ≥ 28 wt.% of the composition. 2 . The battery module according to claim 1 , wherein the battery cells are lithium-ion battery cells. 3 . The battery module according to claim 1 , wherein the thickness of the thermal insulation layer is between 0.2 mm and 4 cm.

4. A method for thermally insulating adjacent battery cells in a battery module by providing an insulating layer of a ceramizable elastomeric silicone material between the adjacent battery cells, the ceramizable elastomeric silicone material being a cured product of a silicone rubber composition comprising: (i) one or more polydiorganosiloxanes having a weight average molecular weight of 200,000 g / mol to 800,000 g / mol, 0.01% to 1% alkenyl and / or alkynyl groups, the one or more polydiorganosiloxanes being present in an amount of 30 wt.% to 70 wt.% of the composition; (ii) a fumed silica filler, wherein the amount of the fumed silica filler is 28.0 wt.% to 40.0 wt.%; (iv) a curing agent selected from the group consisting of: (a) organic peroxides; or (b) a hydrosilylation cure package comprising (b)(i) a hydrosilylation catalyst and (b)(ii) an organopolysiloxane crosslinker having at least three hydrogen groups per molecule; and component (v) when curing agent (iv) is (a) an organic peroxide, or optionally component (vi) when curing agent (iv) is (b) a hydrosilylation cure package, wherein (v) is a compound or complex of platinum metal or a platinum group metal; and (vi) is a hydrosilylation cure inhibitor; wherein the fumed silica filler is partially replaced by (iii) quartz having a particle size of 1 μm to 30 μm, wherein the fumed silica and the quartz are each present in an amount ≥ 10 wt. % of the composition, the maximum total combined amount of fumed silica and quartz present being 40 wt. % of the composition and: [Total wt.% of fumed silica] + [half of the wt.% of quartz] ≥ 28 wt.% of the composition. The method of claim 4 , wherein the battery cell is a lithium-ion battery cell.

6. A use of a ceramic elastomeric silicone material as a thermal insulation layer between adjacent battery cells in a battery module, wherein the ceramic elastomeric silicone material is a cured product of a silicone rubber composition comprising: (i) one or more polydiorganosiloxanes having a weight average molecular weight of 200,000 g / mol to 800,000 g / mol, 0.01% to 1% alkenyl and / or alkynyl groups, the one or more polydiorganosiloxanes being present in an amount of 30 wt.% to 70 wt.% of the composition; (ii) a fumed silica filler, wherein the amount of the fumed silica filler is 28.0 wt.% to 40.0 wt.%; (iv) a curing agent selected from the group consisting of: (a) organic peroxides; or (b) a hydrosilylation cure package comprising (b)(i) a hydrosilylation catalyst and (b)(ii) an organopolysiloxane crosslinker having at least three hydrogen groups per molecule; and component (v) when curing agent (iv) is (a) an organic peroxide, or optionally component (vi) when curing agent (iv) is (b) a hydrosilylation cure package, wherein (v) is a compound or complex of platinum metal or a platinum group metal; and (vi) is a hydrosilylation cure inhibitor; wherein the fumed silica filler is partially replaced by (iii) quartz having a particle size of 1 μm to 30 μm, wherein the fumed silica and the quartz are each present in an amount ≥ 10 wt. % of the composition, the maximum total combined amount of fumed silica and quartz present being 40 wt. % of the composition and: [Total wt.% of fumed silica] + [half of the wt.% of quartz] ≥ 28 wt.% of the composition.

7. The use according to claim 6, wherein the battery cell is a lithium-ion battery cell.

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