Secondary battery pack with improved thermal management

Abstract

The present invention relates to a new secondary battery pack with improved thermal management that can be used in a full electric vehicle (EV), plug-in hybrid electric vehicle (PHEV), hybrid electric vehicle (HEV), or for other vehicle battery packs, and more specifically, to the use of a special material for thermal insulation of a secondary battery pack and further to minimize the propagation of heat dissipation within the battery pack.

Description

[0001] Cross-Referenced Related Applications

[0002] This application is an international application under the Patent Cooperation Treaty, which claims priority to U.S. Provisional Application No. 62 / 456,502, filed February 8, 2017, the entirety of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present invention relates to a new secondary battery pack, particularly those containing lithium ion battery cells, with improved thermal management to allow for use under long term conditions of extreme temperatures. More particularly, the present invention relates to the use of a special material for thermal insulation of secondary battery packs and further to minimize the propagation of thermal deviations within the battery pack. The described secondary battery pack can be used in a full electric vehicle (EV), a plug-in hybrid electric vehicle (PHEV), a hybrid electric vehicle (HEV), or for other vehicle batteries. BACKGROUND

[0004] Batteries can be broadly classified into primary and secondary batteries. Primary batteries, also known as disposable batteries, are intended to be used until they are depleted, after which they are simply replaced with one or more new batteries. Secondary batteries, more commonly known as rechargeable batteries, are capable of being repeatedly recharged and reused, thus offering the benefits of economy, environmental friendliness, and ease of use compared to disposable batteries. Examples of secondary batteries can include nickel-cadmium batteries, nickel-metal hybrid batteries, nickel-hydrogen batteries, lithium secondary batteries, and the like.

[0005] Secondary batteries, particularly lithium ion batteries, have emerged as a key energy storage technology and are now the dominant technology for consumer electronics, industry, transportation, and power storage applications.

[0006] Due to their high potential and their high energy and power density as well as their good lifetime, secondary batteries are now the preferred battery technology, particularly in the automotive industry, as it now can provide longer driving ranges and suitable acceleration for electrically driven vehicles such as hybrid electric vehicles (HEV), battery electric vehicles (BEV), and plug-in hybrid electric vehicles (PHEV). In the current automotive industry, lithium ion battery cells of different sizes and shapes are manufactured and subsequently assembled into packs of different configurations. Automotive secondary battery packs are typically composed of many battery cells, sometimes hundreds or even thousands, to meet the desired power and capacity requirements.

[0007] However, such switching in drive vehicle technology is not without its technical limitations, as the use of electric motors translates into a need for inexpensive batteries with high energy density, long operating life, and the ability to operate in a wide range of conditions. While rechargeable battery cells offer many advantages over disposable batteries, this type of battery is not without its drawbacks. Generally, most of the drawbacks associated with rechargeable batteries are attributed to the battery chemistry used, as these chemistries tend to be less stable than those used in primary batteries. Secondary battery cells, such as lithium ion cells, tend to be more susceptible to thermal management issues, which can occur when an exothermic reaction that generates heat is triggered at elevated temperatures, which further increases the temperature and potentially triggers more damaging reactions. During such an event, a large amount of thermal energy is rapidly released, heating the entire battery up to temperatures of 850°C or higher. As a result of the elevated temperature experienced by the cell, the temperature of adjacent cells in the battery pack will also increase. If the temperature of these adjacent cells is allowed to increase unchecked, they too can enter an unacceptable state with extremely high temperatures within the cell, resulting in a cascading effect where the elevated temperature within a single cell begins to spread throughout the entire battery pack. As a result, the power from the battery pack is interrupted, and the system using the battery pack is more likely to incur widespread collateral damage due to the scale of the damage and the associated release of thermal energy. In the worst case scenario, the heat generated is large enough to cause the battery and materials adjacent to the battery to catch fire.

[0008] Further, due to the characteristics of lithium ion batteries, secondary battery packs operate in an ambient temperature range of -20°C to 60°C. However, even when operating within this temperature range, secondary battery packs can begin to lose their charge capacity or ability (which should occur at ambient temperatures below 0°C). Depending on the ambient temperature, the life cycle capacity or charge ability of the battery can decrease significantly when the temperature begins to fall below 0°C. It can be unavoidable, however, to use lithium ion batteries in situations where the ambient temperature is outside of the optimal ambient temperature range, which is 20°C-25°C. These factors not only significantly shorten the driving distance of a vehicle, but also cause a lot of battery damage. The degradation in energy and power available at low temperatures is due to the decrease in capacity and increase in internal resistance.

[0009] As a result of the above, in a battery or battery assembly having multiple cells, significant temperature variations can occur between different cells, which can be detrimental to the performance of the battery pack. In order to facilitate long life of the overall battery pack, the cells must be below a desired threshold temperature. In order to facilitate pack performance, the temperature difference between cells in a secondary battery pack should be minimized. However, depending on the thermal path to the ambient environment, different cells will reach different temperatures. In addition, for the same reason, different cells reach different temperatures during charging. Therefore, if one cell is at a higher temperature than the other cells, its charge and discharge efficiency will be different, and so it can charge and discharge faster than the other cells. This will result in a decrease in the performance of the overall pack.

[0010] Many solutions have been used to reduce the risk of thermal problems, or to reduce the risk of thermal propagation. They can be found in US patent 8367233, which discloses a battery pack thermal management system comprising at least one encapsulated failure port integrated into at least one wall of a battery pack encapsulation housing, where the encapsulated failure port remains closed during normal operation of the battery pack and opens during a thermal event of the battery pack, whereby the hot gases generated during the thermal event provide a flow path for egress from the battery pack encapsulation housing in a controlled manner.

[0011] Another solution is to develop new battery cell chemistries and / or to modify existing battery cell chemistries. Yet another solution is to provide additional shielding at the level of the battery cell, whereby the flow of thermal energy from a cell experiencing thermal management problems to adjacent cells is inhibited. Still another solution is to use spacer assemblies to maintain the position of a battery experiencing a thermal event at its predetermined position within the battery pack, thereby helping to minimize the thermal effects on adjacent cells.

[0012] Battery pack thermal insulation has also been described to reduce the risk of thermal deviation or their propagation. For example, document US 2007 / 0259258 describes a battery of lithium generators, where the generators are stacked on top of each other and this stack is maintained in a position surrounded by polyurethane foam. An embodiment is also disclosed in which cooling fins are inserted between two generators.

[0013] Document DE 202005010708 describes a starter lead-acid electrochemical generator and electrochemical generators for industrial use, the housing of which comprises a plastic foam, such as polypropylene or polyvinyl chloride, with closed cells.

[0014] Document US2012 / 0003508 describes a battery for a lithium-ion electrochemical generator, comprising a housing; a plurality of lithium-ion electrochemical generators housed within the housing, each generator comprising a container; and a rigid, flame-retardant foam material having closed cells, formed from an electrically insulating material filling the space between the inner wall of the housing and the free surface of the container sidewall of each electrochemical generator, said foam material covering the free surface of the container sidewall of each electrochemical generator for a length occupying at least 25% of the container height. According to one embodiment, the foam material is composed of materials selected from polyurethane, epoxy resin, polyethylene, melamine, polyester, cresol resin, polystyrene, silicone, or mixtures thereof, with polyurethane and mixtures of polyurethane and epoxy resin being preferred. The expansion of the polyurethane resin used in the foam form is recorded to obtain the foam material using the following chemical pathway:

[0015] a) Through a chemical pathway, namely, the reaction of water with isocyanate to produce CO2, which will cause polyurethane foaming;

[0016] b) Evaporation via a physical pathway, i.e., the thermal effect generated by the exothermic reaction between the low-boiling-point liquid and the hydrogen donor compound, or

[0017] c) Injected via air.

[0018] However, when foam materials are used to minimize the adverse effects of any fire and explosion associated with thermal events, rigid foam materials (which are typically produced by reacting, for example, polyisocyanates with isocyanate-reactive materials such as polyols in the presence of a blowing agent) do not exhibit the required high compressive deformation.

[0019] US4418127 describes a modular lithium battery having multiple battery cells, electrical connection devices to connect the cells to an output terminal, and a ventilation device for releasing exhaust byproducts into a chemical scrubber. The stainless steel battery cell housing is infused within an aluminum module housing with a composite epoxy foam material. This foam material is composite in nature to reduce weight, and microballoons have been introduced within it. These microballoons are composed of a composition selected from glass and ceramics, along with additives that reduce flammability.

[0020] Another major problem in the emerging field of electric vehicles is related to the powertrain used, which integrates the engine, automated human operated transmission, shafts and wheels with the final drive to control the speed and generate greater torque to drive the vehicle. The main difference compared to traditional fuel consuming vehicles is that there is no clutch or hydrodynamic torque converter in electric vehicles, so the inherent flexibility of the overall system construction is less than the engine and the transmission system is directly mechanically coupled. This construction has little passive damping effect, which damps disturbances and avoids vibrations, which are most common during low speed range travel. Indeed, the main sound is the magnetic noise, which generates high frequency squeal noise. Vehicles running with electric motors only will also have less masking sound at low frequencies. This means that the requirements for other noise such as liquid or air cooling / heating must be changed for electric batteries as well. Noise during coast down regeneration (battery charging) is also important. So, due to the low damping and lack of passive damping hardware in electric vehicles compared to conventional vehicles, a damping control strategy is needed to minimize powertrain vibrations.

[0021] While many solutions have been taken to try to reduce the risk of thermal intrusion and thermal propagation in the overall battery pack, it is crucial that if a battery pack level thermal event occurs, the human and performance risks are minimized. With the increase in the number of cells in the battery and with the increase in the size of the cells, the necessity and benefits of providing proper thermal management will also increase.

[0022] Furthermore, there is still a need to better insulate the battery cells, in particular lithium ion battery packs, from the effects of low temperatures, which can be encountered when the climate reaches serious low temperatures, which can reach -20°C and even lower.

[0023] In the context of the present application, one of the basic objectives of the present invention is to provide a new battery pack that will provide proper thermal management and will minimize the human and performance risks resulting from uncontrolled thermal events while it is still waiting.

[0024] Another basic objective of the present invention is to provide a new battery pack that will provide damping control to minimize the vibrations of the powertrain and provide better control efficiency in controlling the propagation of noise from the electric battery in use.

[0025] With the present invention, it is sought that the claimed secondary battery pack will solve the problems related to uncontrolled thermal deviation described, in particular for lithium batteries, which will exhibit effective low temperature insulation performance and will provide a damping control strategy to minimize the vibrations of the powertrain.

[0026] All these objectives are achieved, inter alia, by the present invention, which relates to a secondary battery pack, comprising:

[0027] at least one battery module housing 102, in which a plurality of battery cells 103 are arranged, which are electrically connected to each other,

[0028] a silicone rubber composite foam material, which comprises a silicone rubber binder and hollow glass beads, and which partially or completely fills the open spaces of the battery module housing 102 and / or partially or completely covers the battery cells 103 and / or partially or completely covers the module housing 102, and

[0029] an optional cover, which covers the battery module housing 102.

[0030] To achieve this objective, the applicant has fully surprisingly and unexpectedly demonstrated that the choice of silicone rubber as a binder for a composite foam material comprising hollow glass beads makes it possible to overcome problems which could not be solved with similar batteries using organic rubber composite foam materials.

[0031] As used herein, the term "silicone rubber" includes the crosslinked product of any crosslinkable silicone composition. With "silicone rubber composite foam material" is meant a matrix made of silicone rubber, in which hollow glass beads are dispersed.

[0032] Furthermore, it is known that the driving distance of an electric vehicle between charges is calculated at ambient temperature. Electric vehicle drivers are aware that low temperatures reduce the miles available. This loss is caused not only by the electrical heating of the cabin, but also by the inherent slowing down of the electrochemical reactions of the battery, which reduces the capacity at cold. Therefore, the specific choice of silicone rubber as a binder in the composite foam material makes it possible for the foam material to exhibit excellent insulation against low temperatures or below the freezing point.

[0033] Another advantage of using a silicone rubber binder for a composite foam material can be, for example, the embrittlement (or loss of ductility) point, which for a usual organic rubber binder is -20°C to -30°C, while in contrast the binder according to the invention is -60°C to -70°C.

[0034] Another advantage is also related to physical properties such as elasticity, which remain valid for silicone rubber binders even at low temperatures, at which organic rubber binders become brittle.

[0035] Another advantage of using the silicone composite foam material according to the present application is that it has very low water absorption and thus optimally insulates the battery cells from water, which is not desirable for its optimal application. Indeed, in contrast to the silicone composite foam material, conventional silicone foam materials only contain foamed bubbles and have voids that are completely or at least partially connected to each other, which would have the ability to absorb and spread water, which is characteristic of making it difficult to use in electric vehicles, where the battery pack is most often located under the vehicle or in the vehicle floor, so that the use of such a material can be problematic in driving conditions in the rain.

[0036] Because temperature differentials affect the resistance, self-discharge rate, coulombic efficiency, and irreversible capacity and power decay rates of the battery cells over a wide range of chemicals, the secondary battery pack according to the present application allows for uniform thermal conditions for all battery cells in the battery pack or module. This further minimizes the possibility of a state of charge imbalance of the battery cells and the possibility of early failure of good battery cells.

[0037] According to a preferred embodiment, the silicone rubber composite foam material is used as a potting material that is located in the battery module housing 102 to at least partially enclose the plurality of battery cells 103 and / or is located outside the battery module housing 102 to at least partially enclose the battery module housing 102.

[0038] Indeed, the silicone rubber composite foam material partially or completely fills the open space of the battery module housing and / or partially or completely covers the battery cells. The silicone rubber binder provides the composite foam material with mechanical flexibility and thermal stability over a wide temperature range (e.g., -70°C to 200°C). In addition, the silicone rubber binder decomposes into silicon dioxide and silicon oxide at overheat temperatures (up to 850°C) and absorbs a large amount of heat. Therefore, the thermal diffusion from a cell battery to an adjacent cell battery can be effectively insulated by the thermal insulation barrier, which is the silicone rubber composite foam material. The thermal deviation will not be propagated throughout the battery module and thus prevent a threat to the safety of the user. In addition, for some battery modules that have a control circuit board located in the battery module housing, the silicone rubber composite foam material of the present application can be located between the battery cells and the circuit board and between the battery cells and the connecting circuit to reduce the battery heating problem caused by the circuit board and the circuit.

[0039] The silicone formulation contains hollow glass beads and in a preferred embodiment the melting point of the hollow glass beads is similar to the thermal event that occurs in a battery or in a set of batteries in a module, such heating will soften and melt the glass, thereby reducing heat transfer and protecting other batteries around the overheated battery.

[0040] According to a preferred embodiment, the battery cells 103 are of lithium ion type.

[0041] According to another preferred embodiment, the secondary battery pack according to the present application further comprises a plurality of heat dissipation elements located at two or more interfaces between the battery cells, and at least one heat exchange element integrated with the heat dissipation elements, which is installed on one side of the battery module housing 102, whereby the heat generated by the battery cells during charging and discharging of the battery cells is removed through the heat exchange element. It allows to cool the battery cells with higher efficiency than conventional cooling systems, even when there is no space between the battery cells or there is very small space between the battery cells, thereby maximizing the heat dissipation efficiency of the secondary battery pack and allowing to further limit the free space within the secondary battery pack.

[0042] According to another preferred embodiment, the heat dissipation elements according to the present application are made of a thermally conductive material exhibiting high thermal conductivity, and the heat exchange element has one or more coolant channels for allowing a coolant, for example a liquid or a gas, to flow there through.

[0043] There is no particular limitation to the heat dissipation elements according to the present application, as long as each heat dissipation element is made of a thermally conductive material exhibiting high thermal conductivity, for example a metal plate.

[0044] Preferably, the heat exchange element has one or more coolant channels to allow a coolant to flow there through. For example, coolant channels can be formed in the heat exchange element to allow a liquid coolant, for example water, to flow there through, thereby providing superior cooling effect and high reliability compared to conventional air cooling structures.

[0045] According to another preferred embodiment, the secondary battery pack according to the present application further comprises a coolant inlet manifold, a coolant outlet manifold and a plurality of heat exchange tubes as heat dissipation elements and extending between the inlet and outlet manifolds, the heat exchange tubes being located at one or more interfaces between the battery cells, and a coolant is made to flow through to exchange the heat generated by the battery cells during charging and discharging of the battery cells.

[0046] Hollow glass beads are used in the composite foam material of the present application and serve to reduce the density of the foam material. Hollow glass beads and in particular hollow glass microspheres are well suited for this application because, in addition to having an excellent isotropic compressive strength, they also have the lowest density of fillers that will be useful to make composite foam materials of high compressive strength. The combination of high compressive strength and low density makes hollow glass microspheres a filler with many advantages according to the present application.

[0047] According to an embodiment, the hollow glass beads are hollow borosilicate glass microspheres, also known as glass bubbles or glass microbubbles.

[0048] According to another embodiment, the hollow borosilicate glass microspheres have a true density of 0.10 grams per cubic centimeter (g / cc) to 0.65 grams per cubic centimeter (g / cc).

[0049] The term "true density" is the quotient obtained by dividing the mass of a glass bubble sample by the true volume of that mass of glass bubbles, as measured by a gas pycnometer. The "true volume" is the aggregate volume of the glass bubbles, not the bulk volume.

[0050] According to another embodiment, the hollow glass beads are present in an amount of up to 80% by volume in the silicone rubber composite foam material described below or in the liquid cross-linkable silicone composition precursor of the silicone rubber composite foam material described below, and most preferably from 5% to 70% by volume of the silicone rubber composite foam material described below or of the liquid cross-linkable silicone composition precursor of the silicone rubber composite foam material described below.

[0051] According to a preferred embodiment, the hollow glass beads are selected from the group consisting of 3M TM glass bubbles float series (A16 / 500, G18, A20 / 1000, H20 / 1000, D32 / 4500 and H50 / 10000 EPX glass bubble products) and 3M TM glass bubble series (such as but not limited to K1, K15, S15, S22, K20, K25, S32, S35, K37, XLD3000, S38, S38HS, S38XHS, K46, K42HS, S42XHS, S60, S60HS, iM16K, iM30K glass bubble products) sold by 3M Company. The glass bubbles described exhibit different crush strengths from 1.72 MegaPascal (250 psi) to 186.15 MegaPascal (27000 psi) at which pressure 10% by volume of the first plurality of glass bubbles disintegrate. Other glass bubbles sold by 3M such as 3M TM glass bubbles - float series, 3M TM glass bubbles - HGS series and 3M TM Surface treated glass bubbles can also be used in the present invention.

[0052] According to a preferred embodiment, the glass bubbles are selected from the group consisting of those having a crush strength of 1.72 MegaPascal (250 psi) to 186.15 MegaPascal (27000 psi) at which pressure 10% by volume of the first plurality of glass bubbles disintegrate.

[0053] According to a most preferred embodiment, the hollow glass beads are selected from the group consisting of 3M TM glass bubble series S15, K1, K25, iM16K, S32 and XLD3000.

[0054] To fill the free space with the silicone rubber composite foam material according to the present application, one can:

[0055] a) use a liquid cross-linkable silicone composition precursor of the silicone rubber composite foam material comprising hollow glass beads, which starts to fill the free space and to cure via cross-linking after injection or free flow,

[0056] b) or use a machined or pre-molded block of the silicone rubber composite foam material comprising hollow glass beads, which is inserted into the housing at assembly.

[0057] The use of a liquid cross-linkable silicone composition precursor of the silicone rubber composite foam material comprising hollow glass beads in a battery facilitates its filling compared to the conventional liquid cross-linkable silicone precursor of silicone foam materials, because the foaming process of conventional foam materials generates foaming bubbles and voids with full or at least partial connections to each other, which leads to many defects and filling problems within the obtained silicone foam material.

[0058] Indeed, conventional silicone foam materials are obtained by several processes, for example by adding a thermally decomposable blowing agent, or by molding and curing while generating hydrogen gas by-products. In the process of adding a thermally decomposable blowing agent, the toxicity and odor of the decomposed gas are problematic. The process using hydrogen gas by-products in the curing step suffers from problems such as the potential explosion of hydrogen gas and the careful handling of the uncured composition during standby storage. Furthermore, the gas generating processes encounter difficulties in forming a controlled and uniform cell in the battery.

[0059] The use of expandable silicone rubber composite foam material facilitates the filling of the free space within the battery, because the swelling pressure pushes the foam material into all the chambers and recesses of the geometry to be filled. Also, this process allows the filling of any geometry, which is not possible using preformed blocks.

[0060] Silicone rubber, which is used as a binder in the composite foam material according to the present application, is often referred to as silicone elastomer, which comprises 3-4 essential ingredients. These ingredients are (i) one or more reactive silicone polymers, (ii) possibly one or more fillers, (iii) a cross-linking agent, and (iv) a catalyst. Generally, there are two main types of silicone rubber compositions, which are heat vulcanized (HTV) silicone rubber and room temperature vulcanized (RTV) silicone rubber. Heat vulcanized or high temperature vulcanized (HTV) silicone rubber compositions are often further distinguished as high consistency rubber (HCR) or liquid silicone rubber (LSR) depending on the uncured viscosity of the composition. However, the term "room temperature vulcanized" (RTV) silicone rubber compositions can be misleading, because some RTV compositions can require a small amount of heat to react at a reasonable speed.

[0061] The silicone rubber binder in which the hollow glass beads are dispersed can be obtained by curing an addition-curing type organopolysiloxane composition, a peroxide-curing type organopolysiloxane composition or a condensation type organopolysiloxane composition.

[0062] Such silicone compositions are well known to those skilled in the art of silicones. An addition-curing type organopolysiloxane composition is preferably defined as comprising essentially (1) 100 parts by weight of an organopolysiloxane having at least two alkenyl groups bonded to silicon atoms in each molecule, (2) 0.1 to 50 parts by weight of an organohydrogenpolysiloxane having at least two, preferably at least three, hydrogen atoms (i.e. SiH groups) bonded to silicon atoms in each molecule, and (3) a catalytic amount of an addition reaction catalyst. A peroxide-curing type organopolysiloxane composition is preferably defined as comprising essentially (1) 100 parts by weight of an organopolysiloxane having at least two alkenyl groups bonded to silicon atoms in each molecule, and (2) a catalytic amount of an organic peroxide. Condensation type organopolysiloxane compositions (which crosslink via condensation) typically include a silicone oil, typically polydimethylsiloxane, which has hydroxyl end groups, optionally pre-functionalized with a silane to make them hydrolysable and condensable, and a crosslinker, a condensation catalyst, a conventional tin salt or a titanium alkoxide.

[0063] According to one preferred embodiment, the silicone rubber composite foam material is obtained by curing an addition-curing type organopolysiloxane composition X. This embodiment offers some advantages over one-component systems (condensation type organopolysiloxane compositions), especially in production environments. Since the curing is initiated by a catalyst and not by moisture (as in the case of condensation-cured silicones), they do not have the problem of section thickness. Indeed, they are advantageously used for applications such as potting, encapsulation and large castings. Addition-curing type organopolysiloxane compositions do not release reaction by-products, so they can be cured in a closed environment. Their curing can also be significantly accelerated by thermal curing, but the curing can be easily obtained without heating, by adjusting the level of inhibitor and / or catalyst at ambient temperature 20°C (+ / - 5°C), which is a big advantage compared to peroxide curing which requires temperatures higher than 90°C.

[0064] According to another preferred embodiment, the addition-curing type organopolysiloxane composition X comprises:

[0065] a) at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing 2 to 14 carbon atoms, preferably said alkenyl groups are selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups,

[0066] b) at least one silicon compound B having at least two and preferably at least three hydrogen atoms bonded to silicon per molecule,

[0067] c) hollow glass beads D, and preferably hollow borosilicate glass microspheres,

[0068] d) a hydrosilylation catalyst C,

[0069] e) optionally at least one cure rate control agent G which slows the cure rate of the silicone composition,

[0070] f) optionally at least one reactive diluent E which reacts by hydrosilylation reaction, and

[0071] g) optionally at least one additive H such as pigments, dyes, clays, surfactants, hydrogenated castor oil, wollastonite, aluminum trihydrate, magnesium hydroxide, kaolin, huntite, hydromagnesite, exfoliated graphite, zinc borate, mica or fumed silica.

[0072] According to another preferred embodiment, the addition-cure type organopolysiloxane composition X comprises:

[0073] a) at least one organopolysiloxane A of the following formula:

[0074]

[0075] wherein:

[0076] - R and R" are independently of each other selected from the group consisting of C1-C 30 hydrocarbyl groups, and preferably R and R" are alkyl groups selected from the group consisting of methyl, ethyl, propyl, trifluoropropyl, and phenyl, and most preferably R is methyl,

[0077] - R' is a C1-C 20 alkenyl group, and preferably R' is selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably R' is vinyl, and

[0078] - n is an integer value of 5 to 1000, and preferably 5 to 100,

[0079] b) at least one silicon compound B comprising at least two hydrogen atoms bonded to silicon per molecule, and preferably a mixture of two silicon compounds B, wherein one comprises two telechelic hydrogen atoms bonded to silicon per molecule and no pendant hydrogen atoms bonded to silicon per molecule, and the other comprises at least three hydrogen atoms bonded to silicon per molecule,

[0080] c) an effective amount of a hydrosilylation catalyst C, and preferably a platinum-based hydrosilylation catalyst C,

[0081] d) hollow glass beads D, and preferably hollow borosilicate glass microspheres,

[0082] e) optionally and preferably at least one reactive diluent E for reducing the viscosity of the composition, and which reacts by hydrosilylation reaction, and is selected from:

[0083] - a silicon compound comprising a single hydrosilicon group per molecule, and

[0084] - an organic compound containing a single olefinically unsaturated group, preferably the organic compound is an organic alpha-olefin containing 3 to 20 carbon atoms, and most preferably selected from the group consisting of dodecene, tetradecene, hexadecene, octadecene and combinations of these, and all having terminal vinyl groups,

[0085] - an organopolysiloxane having a single telechelic alkenyl group, and preferably the telechelic alkenyl group is selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably is vinyl,

[0086] f) optionally at least one additive H such as a pigment, a dye, a clay, a surfactant, hydrogenated castor oil, wollastonite, aluminum trihydrate, magnesium hydroxide, kaolin, huntite, nesquehonite, exfoliated graphite, zinc borate, mica or fumed silica, and

[0087] g) optionally at least one cure rate control agent G which slows the cure rate of the silicone composition.

[0088] According to another preferred embodiment, the reactive diluent E:

[0089] - is selected from the group consisting of dodecene, tetradecene, hexadecene, octadecene or combinations of these, and all having terminal vinyl groups, or

[0090] - is a liquid organopolysiloxane of formula I

[0091]

[0092] wherein:

[0093] - R and R 2independently of one another selected from C1-C 30 hydrocarbyl, and preferably they are selected from methyl, ethyl, propyl, trifluoropropyl and phenyl, and most preferably methyl,

[0094] -R 1 is C1-C 20 alkenyl, and preferably R 1 is selected from ethenyl, allyl, hexenyl, decenyl or tetradecenyl, and most preferably R 1 is ethenyl, and

[0095] x is 0-100, and x is chosen so as to reduce the viscosity of the addition-curable organopolysiloxane composition X compared to the same composition without the reactive diluent.

[0096] According to one preferred embodiment, the organopolysiloxane A is selected from dimethylpolysiloxanes containing dimethylvinylsilyl end groups.

[0097] According to another preferred embodiment, wherein:

[0098] - the viscosity of the organopolysiloxane A at 25°C is from 5 mPa.s to 60 000 mPa.s; and preferably from 5 mPa.s to 5000 mPa.s, and most preferably from 5 mPa.s to 350 mPa.s, and

[0099] - the viscosity of the silicon compound B comprising two hydrogen atoms distal to silicon bonded to silicon per molecule and no pendant hydrogen atom bonded to silicon per molecule at 25°C is from 5 to 100 mPa.s, and

[0100] - the viscosity of the silicon compound B comprising at least three hydrogen atoms bonded to silicon per molecule at 25°C is from 5 to 2000 mPa.s.

[0101] All the viscosities considered in the present description correspond to the order of magnitude of dynamic viscosity, measured at 25°C with a machine of the Brookfield type in a manner known per se. With regard to fluid products, the viscosities considered in the present description are the dynamic viscosities at 25°C, called "Newtonian" viscosities, i.e. dynamic viscosities measured at a sufficiently low shear rate gradient in a manner known per se so that the viscosity measured is independent of the rate gradient.

[0102] According to a preferred embodiment, the viscosity at 25°C of said organopolysiloxane A and of said silicon compound B comprising at least two hydrogen atoms bonded to silicon per molecule is chosen so that the viscosity at 25°C of the addition-curable organopolysiloxane composition X is between 500 mPa.s and 300 000 mPa.s so that it can be injected into the battery module housing 102. If the option of pouring the composition into the battery module housing 102 is chosen, the components of said addition-curable organopolysiloxane composition X are chosen so that its viscosity is between 500 mPa.s and 5000 mPa.s and most preferably between 500 mPa.s and 2500 mPa.s.

[0103] Examples of hydrosilation catalysts C are hydrosilation catalysts such as Karstedt's catalyst as shown in U.S. Patent No. 3,715,334 or other platinum or rhodium catalysts known to those skilled in the art and also include microencapsulated hydrosilation catalysts such as those known in the art, for example, see U.S. Patent No. 5,009,957. However, the hydrosilation catalysts associated with the present application can comprise at least one of the following elements: Pt, Rh, Ru, Pd, Ni such as Raney nickel, and combinations thereof. The catalysts are optionally bound to an inert or active support. Examples of preferred catalysts that can be used include platinum-based catalysts such as chloroplatinic acid, alcoholic solutions of chloroplatinic acid, complexes of platinum and olefins, complexes of platinum and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane and platinum supported on powders and the like. Platinum catalysts are well described in the literature. In particular, one can mention the complexes of platinum and organic products described in U.S. Patent Nos. 3,159,601, 3,159,602 and 3,220,972 and European Patents EP-A-0 574 59, EP-188 978 and EP-A-190 530, and the complexes of platinum and vinylated organopolysiloxanes described in U.S. Patent Nos. 3,419,593, 3,715,334, 3,377,432, 3,814,730 and 3,775,452 to Karstedt. In particular, platinum-based catalysts are particularly desirable.

[0104] If desired, examples of cure rate control agents G, also known as inhibitors, are designed to slow the cure of the compounded silicone. Cure rate control agents are well known in the art, and examples of such materials can be found in U.S. Patents. U.S. Patent 3,923,705 is directed to the use of vinyl containing cyclosiloxanes. U.S. Patent 3,445,420 describes the use of acetylenic alcohols. U.S. Patent 3,188,299 shows the effectiveness of heterocyclic amines. U.S. Patent 4,256,870 describes alkyl maleates for controlling cure. Olefinic siloxanes can also be used as described in U.S. Patent 3,989,667. Vinyl containing polydiorganosiloxanes have also been used, and this technology can be seen in U.S. Patents 3,498,945, 4,256,870 and 4,347,346. The preferred inhibitors for use in such compositions are methylvinylcyclosiloxane, 3-methyl-l-butyn-3-ol and l-ethynyl-l-cyclohexanol, and the most preferred is 1,3,5,7-tetramethyl-l,3,5,7-tetravinyl-cyclotetrasiloxane, in amounts of 0.002% to 1.00% of the silicone compound, depending on the desired cure rate.

[0105] The preferred cure rate control agents G are selected from the group consisting of:

[0106] - 1,3,5,7-tetramethyl-l,3,5,7-tetravinyl-cyclotetrasiloxane.

[0107] - 3-methyl-l-butyn-3-ol, and

[0108] - 1-ethynyl-l-cyclohexanol.

[0109] To achieve longer working times or "pot life", the amount of cure rate control agent G is adjusted to achieve the desired "pot life". The concentration of catalyst inhibitor in the silicone composition of the present invention is sufficient to retard the cure of the composition at ambient temperatures without preventing or unduly prolonging the cure at elevated temperatures. This concentration will vary widely depending on the particular inhibitor used, the nature and concentration of the hydrosilylation catalyst, and the nature of the organohydrogenpolysiloxane. Inhibitor concentrations as low as 1 mole of inhibitor per mole of platinum group metal will produce satisfactory storage stability and cure rates in some cases. In other cases, inhibitor concentrations as high as 500 or more moles of inhibitor per mole of platinum group metal can be required. The optimum concentration of a particular inhibitor in a given silicone composition can be readily determined by routine experimentation.

[0110] According to a preferred embodiment, for the addition-curing organopolysiloxane composition X, the weight ratio of organopolysiloxane A, reactive diluent E, if present, and silicon compound B is such that the overall molar ratio of hydrogen atoms bonded to silicon to all alkenyl groups bonded to silicon is 0.35 to 10, and preferably 0.4 to 1.5.

[0111] Some additives H, such as pigments, dyes, clays, surfactants, hydrogenated castor oil, wollastonite or fumed silica, which modify the flowability of the compounded silicone product, can also be used in the addition-curing organopolysiloxane composition X.

[0112] By "dye" is meant a colored or fluorescent organic substance which imparts color to a substrate by selective absorption of light. By "pigment" is meant a colored, black, white or fluorescent particulate organic or inorganic solid which is generally insoluble in the vehicle or substrate into which it is introduced and is substantially unaffected by the physical and chemical influences thereof. It changes appearance by selective absorption and / or by scattering of light. Pigments generally retain the crystalline or particulate structure throughout the coloring process. Pigments and dyes are well known in the art and need not be described here.

[0113] Clays are products which are known per se, their description being given for example in the publication "Mineralogie des argiles [Mineralogy of clays], S. Caillere, S. Henin, M. Rautureau, 2nd edition 1982, Masson". Clays are silicates which contain cations which can be chosen from the group comprising calcium, magnesium, aluminium, sodium, potassium and lithium cations and mixtures thereof. Examples of such products which can be mentioned include clays of the montmorillonite group such as montmorillonite, hectorite, beidellite, saponite and saponite, as well as vermiculite, stevensite and chlorite group. These clays can be of natural or synthetic origin. The said clays are preferably beidellite or hectorite and these clays can be modified with chemical compounds chosen from the group comprising quaternary amines, tertiary amines, amine acetates, imidazolines, amine soaps, fatty sulphates, alkyl aryl sulphonates and amine oxides and mixtures thereof. The clays which can be used in the application are synthetic hectorites (also known as synthetic laponite), such as the products sold by Laporte under the names Laponite XLG, Laponite RD and Laponite RDS (these products are sodium magnesium silicates and in particular lithium magnesium sodium silicates); beidellite, such as the product sold by Rheox under the name Bentone HC; magnesium aluminium silicates, in particular hydrated, such as the product sold by the company R.T. Vanderbilt under the name Veegum Ultra, or calcium silicates and in particular in synthetic form, which is sold by the company CELITE ET WALSH ASS under the name Micro-Cel C.

[0114] Many silicone polyether surfactants are available, but the preferred silicone polyether for thickening the silicone compound of the application is SP3300 from Elkem Silicones USA.

[0115] Another preferred additive H is a rheology modifier such as Thixcin R, which is a hydrogenated castor oil from Elementis Specialties, New Jersey, USA.

[0116] Wollastonite, also known as calcium metasilicate, is a naturally occurring mineral which can be added as a flame retardant, the amount added varying depending on the application and being from 1 to 15 parts by weight, based on 100 parts by weight of the addition-cured organopolysiloxane composition X. The wollastonite which can be used in the application is in the form of a mineral, having an acicular morphology, which is needle-like in shape. The preferred wollastonite grades are chosen from the group comprising the materials supplied by Minerals, Inc., Willsboro N.Y.

[0117] Aluminum trihydrate (ATH) is a commonly used flame retardant filler. It decomposes when heated above 180-200°C, at which temperature it absorbs heat and releases water to extinguish the fire. Magnesium hydroxide (MDH) has a higher thermal stability than ATH. The endothermic (heat absorbing) decomposition starts at 300°C, from which water is released, which can act as a flame retardant.

[0118] Calcium-magnesium carbonate / hydromagnesite blend (Mg3Ca(C03)4 / Mg5(C03)4(OH)2.4H20). Calcium-magnesium carbonate and hydromagnesite almost invariably exist as a mixture. Hydromagnesite starts to decompose at 220°C (open air) to 250°C (under extruder pressure), which is high enough to make it useful as a flame retardant. Hydromagnesite gives off water and absorbs heat, much like ATH and MDH. In contrast, calcium-magnesium carbonate decomposes above 400°C, endothermically, but releases carbon dioxide.

[0119] Fumed silica can also be used as additive H to modify the rheology of these materials. Fumed silica can be obtained by high temperature pyrolysis of volatile silicon compounds in an oxyhydrogen flame, resulting in finely dispersed silica. This method can especially obtain hydrophilic silicas, which have a high number of silanol groups on their surface, which will tend to thicken silicone compositions more than silicas with a low silanol level. Such hydrophilic silicas are for example sold under the names Aerosil 130, Aerosil 200, Aerosil 255, Aerosil 300 and Aerosil 380 by Degussa and under the names Cab-O-Sil HS-5, Cab-O-Sil EH-5, Cab-O-Sil LM-130, Cab-O-Sil MS-55 and Cab-O-Sil M-5 by Cabot. The surface of the silicas can be chemically modified via chemical reactions, which lead to a reduction of the number of silanol groups. In particular, the silanol groups can be replaced by hydrophobic groups: thus hydrophobic silicas are obtained. The hydrophobic groups can be:

[0120] - trimethylsiloxy groups, which are obtained especially by treating fumed silica in the presence of hexamethyldisilazane. According to CTFA (6th edition, 1995), silicas thus treated are called "silylated silicas". They are for example sold under the name Aerosil R812 by Degussa and under the name Cab-O-Sil TS-530 by Cabot, or

[0121] - dimethylsiloxy or polydimethylsiloxane groups, which are obtained especially by treating fumed silica in the presence of polydimethylsiloxane, or methyldichlorosilane.

[0122] According to CTFA (6th edition, 1995), the thus treated silicas are called "dimethylsilylated silicas". They are sold, for example, under the names Aerosil R972 and Aerosil R974 by Degussa, and Cab-O-Sil TS-610 and Cab-O-Sil TS-720 by Cabot. The fumed silicas preferably have a particle size which can be in the nanometer to micrometer range, for example approximately 5-200 nm.

[0123] According to another preferred embodiment, the addition-curing organopolysiloxane composition X is stored before use as a multi-component RTV comprising at least two separate packages, which are preferably airtight, while the hydrosilylation catalyst C is not present in the same package as the silicon compound B or as the reactive diluent E, when it is present and when it is a silicon compound comprising a single hydrosilyl group per molecule.

[0124] According to another preferred embodiment, the addition-curing organopolysiloxane composition X is stored before use as a multi-component RTV comprising at least two separate packages, which are preferably airtight:

[0125] a) the first package A1 comprises:

[0126] - 100 parts by weight of at least one organopolysiloxane A according to the application and as defined above,

[0127] - 5-30 parts by weight of hollow glass beads D according to the application and as defined above, and

[0128] - 0-30 parts by weight and preferably 5-30 parts by weight of at least one reactive diluent E according to the application and as defined above, and

[0129] - 4-150 ppm of a platinum-based hydrosilylation catalyst C, calculated on the basis of the metal platinum;

[0130] b) the second package A2 comprises:

[0131] - 100 parts by weight of at least one organopolysiloxane A according to the application and as defined above,

[0132] - 10-70 parts by weight of a silicon compound B according to the application and as defined above, which comprises two bonded remote chiral hydrogen atoms per molecule to silicon,

[0133] - 5-25 parts by weight of a silicon compound B according to the application and as defined above, which comprises at least three bonded hydrogen atoms per molecule to silicon,

[0134] - 5 to 30 parts by weight of hollow glass beads D according to the present application and as defined above, and

[0135] - an effective amount of at least one cure rate control agent G which slows the cure rate.

[0136] Another object of the present application relates to a method of preparing a secondary battery pack according to the present application and as defined above, comprising the steps of:

[0137] a) preparing at least one battery module housing 102 in which a plurality of battery cells 103 are arranged which are electrically connected to each other,

[0138] b) introducing into said battery module housing 102 an addition-cure type organopolysiloxane composition X as defined in claim 3 or 11,

[0139] c) completely or partially filling said battery module housing 102, and

[0140] d) allowing the cure to take place to form a silicone rubber composite foam material comprising a silicone rubber binder and hollow glass beads, and optionally

[0141] e) covering the battery module housing 102 with a lid.

[0142] A preferred embodiment of the above method according to the present application relates to a method of preparing an addition-cure type organopolysiloxane composition X comprising the steps of:

[0143] a) feeding into a base feed line a liquid silicone base MS1 comprising:

[0144] i) at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing 2 to 14 carbon atoms, preferably said alkenyl groups are selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups,

[0145] ii) hollow glass beads D, and preferably hollow borosilicate glass microspheres D1,

[0146] iii) at least one silicon compound B having at least two and preferably at least three hydrogen atoms bonded to silicon per molecule, and

[0147] iv) optionally a cure rate control agent G which slows the cure rate,

[0148] b) feeding into a catalyst feed line a catalyst masterbatch MC comprising:

[0149] i) at least one hydrosilylation catalyst C; and

[0150] i) at least one organic polysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, preferably said alkenyl groups are selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups;

[0151] c) feeding an inhibitor masterbatch Ml comprising:

[0152] i) a cure rate control agent G which slows the cure rate; and

[0153] i) at least one organic polysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, preferably said alkenyl groups are selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups; and

[0154] d) optionally feeding an additive masterbatch MA comprising:

[0155] i) at least one additive H such as a pigment, a dye, a clay, a surfactant, hydrogenated castor oil, wollastonite, aluminium trihydrate, magnesium hydroxide, talc, huntite, hydromagnesite, exfoliated graphite, zinc borate, mica or fumed silica, and

[0156] i) at least one organic polysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, preferably said alkenyl groups are selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups; and

[0157] e) introducing said liquid silicone base MS1, said catalyst masterbatch MC and said inhibitor masterbatch Ml and optionally said additive masterbatch MA into a tank to obtain an addition-cure silicone composition X.

[0158] A first advantage of said preferred embodiment is that the rate of the crosslinking reaction of said addition-cure silicone composition X is adjusted by the addition of a cure rate control agent G. Because this addition of a basic component is done via the use of a specific feed line, the level of inhibitor can be easily changed by the operator, which allows him to increase the cure rate or to lower the temperature at which the fast cure starts. This is a key advantage because the construction of newly designed secondary battery packs involves more and more complex shapes, which means that the cure rate has to be carefully adjusted from case to case.

[0159] The second major advantage is that the inhibitor level and hence the temperature at which the rapid cure starts can now be reduced. This can be important if the components present in the battery pack are somewhat temperature sensitive.

[0160] A preferred embodiment according to the above process of the present application relates to the preparation of an addition-curable organopolysiloxane composition X comprising the steps of:

[0161] a) feeding into a base feed line a liquid silicone base MS2 comprising:

[0162] i) at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, preferably said alkenyl groups are selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups, and

[0163] ii) at least one silicon compound B having at least two and preferably at least three hydrogen atoms bonded to silicon per molecule,

[0164] iii) optionally a cure rate control agent G which slows the cure rate,

[0165] b) feeding into a catalyst feed line a catalyst masterbatch MC comprising:

[0166] i) at least one hydrosilylation catalyst C; and

[0167] ii) optionally at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, preferably said alkenyl groups are selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups;

[0168] c) feeding into an inhibitor feed line an inhibitor masterbatch Ml comprising:

[0169] i) a cure rate control agent G which slows the cure rate; and

[0170] ii) optionally at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, preferably said alkenyl groups are selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups; and

[0171] d) optionally feeding into an additive feed line an additive masterbatch MA comprising:

[0172] i) at least one additive H, such as pigments, dyes, clays, surfactants, hydrogenated castor oil, wollastonite, aluminum trihydrate, magnesium hydroxide, saponite, huntite, hydro-magnesite, exfoliated graphite, zinc borate, mica or fumed silica, and

[0173] ii) optionally at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing 2 to 14 carbon atoms, preferably said alkenyl groups are selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups;

[0174] e) introducing said liquid silicone base MS2, said catalyst masterbatch MC and said inhibitor masterbatch Ml and optionally said additive masterbatch MA into a stirred tank; and

[0175] f) operating said stirred tank, thereby mixing said liquid silicone base MS1, said catalyst masterbatch MC and said inhibitor masterbatch Ml and optionally said additive masterbatch MA, preferably by using a high flow, low shear mixer, and

[0176] g) adding hollow glass beads D and preferably hollow borosilicate glass microspheres D1 to said stirred tank, preferably by using a gravity discharge or screw feeder to obtain an addition-cure organopolysiloxane composition X.

[0177] All components of the preferred embodiment of the addition-cure organopolysiloxane composition X have been described above.

[0178] According to one preferred embodiment, the secondary battery pack according to the present application is located within a vehicle.

[0179] It is to be understood that as used herein, the term "vehicle" includes conventional engine vehicles such as passenger cars, including sport utility vehicles (SUVs), buses, trucks, various commercial vehicles, watercraft, including various boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., fuels derived from non-petroleum sources). As referred to herein, a hybrid vehicle is a vehicle having two or more power sources, such as a vehicle powered by both gasoline and electricity.

[0180] In another preferred embodiment, the secondary battery pack according to the present application is located in an automotive engine vehicle.

[0181] In another embodiment, the secondary battery pack according to the invention is located in an all-electric vehicle (EV), a plug-in hybrid electric vehicle (PHEV), or a hybrid electric vehicle (HEV).

[0182] In another embodiment, the secondary battery pack according to the invention is located in an airplane, small boat, ship, train, or wall unit. Attached Figure Description

[0183] Figure 1 A top view of an uncovered secondary battery pack is provided, with the batteries located inside the pack.

[0184] Figure 2 A perspective view of the secondary battery pack is provided, with the batteries located within the battery pack;

[0185] Figure 3 A top view of a battery pack in a secondary battery pack is provided, showing the silicone rubber composite foam material according to the invention filling the spaces between the batteries and the remaining spaces of the battery pack.

[0186] Figure 4 A top view of a battery cell in a secondary battery pack is provided, which is covered with a silicone rubber composite foam material according to the invention, and the foam material fills the space between the cells and the remaining space in the battery pack.

[0187] Figure 5 and 6 Illustrations are provided of two preferred embodiments of a method for producing an addition-curing organopolysiloxane composition X, wherein an inhibitor masterbatch Ml and a catalyst masterbatch MC are respectively fed into other components to control the curing rate.

[0188] Figure 1 and 2 This shows that the battery cells 103 can be housed very tightly together within the battery module housing 102. In one embodiment of the invention, after the battery has been placed and installed ( Figure 3 , 104) The crosslinkable silicone composition according to the invention and the precursor of a lightweight silicone rubber composite foam containing a silicone rubber binder and hollow glass beads are poured into the battery module housing 102, and a silicone composite foam is formed upon curing. Figure 4 ,105).

[0189] Figure 5A process for producing an addition-curable organopolysiloxane composition X according to an embodiment of the present application is shown, wherein the liquid silicone base MS1 is stored in storage tank 1, the catalyst masterbatch MC is stored in storage tank 20, the inhibitor masterbatch Ml is stored in storage tank 50 and the additive masterbatch MA is stored in storage tank 65, and are fed into their respective feed lines 200, 210, 220 and 230, respectively. The storage tank 1 of liquid silicone base MS2 is connected to the mixing tank 80 via a feed pump 10 (which can be any large reciprocating pump) and via an optional feed rate regulator 15. The storage tank 20 of catalyst masterbatch MC is connected to the mixing tank 80 via a feed pump 25 (which can be any small piston reciprocating pump, gear pump, micro-actuated injection pump or other active reciprocating pump), and via an optional feed rate regulator 30. The storage tank 50 of inhibitor masterbatch Ml is connected to the mixing tank 80 via a feed pump 55 (which can be any small piston reciprocating pump, gear pump, micro-actuated injection pump or other active reciprocating pump), and via an optional feed rate regulator 60. The storage tank 65 of additive masterbatch MA is connected to the mixing tank 80 via a feed pump 70 (which can be any small piston reciprocating pump, gear pump, micro-actuated injection pump or other active reciprocating pump), and via an optional feed rate regulator 75. When the liquid silicone base MS2, the catalyst masterbatch MC and the inhibitor masterbatch Ml and optionally the additive masterbatch MA are introduced into the mixing tank 80; the resulting mixture is mixed, preferably by using a high flow low shear mixer, to produce the addition-curable organopolysiloxane composition X according to the present application. The composition is now ready for introduction into the battery module housing 102 by means 100, which can be introduced via injection equipment or via a pump introduction that allows for free flow to fill the free space of the battery module housing 102 and cure via cross-linking.

[0190] Figure 6A method of producing an addition-curable organopolysiloxane composition X according to another embodiment of the present application is shown, wherein the liquid silicone base MS2 is stored in a storage tank 1, the catalyst masterbatch MC is stored in a storage tank 20, the inhibitor masterbatch Ml is stored in a storage tank 50 and the additive masterbatch MA is stored in a storage tank 65, and are fed into their respective feed lines 200, 210, 220 and 230, respectively. The storage tank 1 of the liquid silicone base MS2 is connected to a mixing tank 80 via a feed pump 10 (which can be any large reciprocating pump), and via an optional feed rate regulator 15. The storage tank 20 of the catalyst masterbatch MC is connected to the mixing tank 80 via a feed pump 25 (which can be any small piston reciprocating pump, gear pump, micro- injection pump or other active reciprocating pump), and via an optional feed rate regulator 30. The storage tank 50 of the inhibitor masterbatch Ml is connected to the mixing tank 80 via a feed pump 55 (which can be any small piston reciprocating pump, gear pump, micro-injection pump or other active reciprocating pump), and via an optional feed rate regulator 60. The storage tank 65 of the additive masterbatch MA is connected to the mixing tank 80 via a feed pump 70 (which can be any small piston reciprocating pump, gear pump, micro-injection pump or other active reciprocating pump), and via an optional feed rate regulator 75. When the liquid silicone base MS2, the catalyst masterbatch MC and the inhibitor masterbatch Ml and optionally the additive masterbatch MA are introduced into the mixing tank 80; the resulting mixture is mixed, preferably by using a high flow, low shear mixer. To the resulting mixture, hollow glass beads D and preferably hollow borosilicate glass microspheres Dl (which are stored in a storage tank 90 (preferably a hopper)) are directly transferred by gravity discharge or via a screw feeder 95 to the mixing tank 80 to produce the addition-curable organopolysiloxane composition X according to the present application. The composition can now be used to introduce into the battery module housing 102 by means 100 which can be introduced via injection equipment or via a pump introduction allowing free flow to fill the free space of the battery module housing 102 and cure via cross-linking.

[0191] Other advantages provided by the present application will become apparent from the following description examples. Examples

[0192] I) Definitions of components

[0193] - organopolysiloxane Al = polydimethylsiloxane with dimethylvinylsilyl end units, viscosity at 25°C is 80 mPa.s - 120 mPa.s;

[0194] Organopolysiloxane A2 = polydimethylsiloxane, with dimethylvinylsilyl end units, viscosity at 25°C between 500 mPa.s and 650 mPa.s;

[0195] - organopolysiloxane B1 (CE) as chain extender = polydimethylsiloxane, with dimethylsilyl hydride end units, viscosity at 25°C between 7 mPa.s and 10 mPa.s and having the following formula: M'D x M'

[0196] wherein:

[0197] - D is a siloxy unit of formula (CH3)2SiO 2 / 2 - M' is a siloxy unit of formula (CH3)2(H)SiO

[0198] 1 / 2

[0199] - and x is an integer between 8 and 11 ;

[0200] - organopolysiloxane B2 (XL) as crosslinking agent, viscosity at 25°C between 18 mPa.s and 26 mPa.s, more than 10 SiH reactive groups present (on average 16-18 SiH reactive groups): poly(methyl hydrogen)(dimethyl)siloxane, with SiH groups in the chain and at the chain end (alpha / omega),

[0201] - hollow glass beads D1 : 3M TM Glass Bubbles® series S15, sold by the company 3M, particle size (50% by volume) = 55 microns, isostatic crush strength: test pressure 300 psi (2.07 MPa), true density (g / cc) = 0.15.

[0202] - hollow glass beads D2: 3M TM Glass Bubbles® series K25, sold by the company 3M, particle size (50% by volume) = 55 microns, isostatic crush strength: test pressure 750 psi, true density (g / cc) = 0.25.

[0203] - hollow glass beads D3: 3M TM iM16K Glass Bubbles®, sold by the company 3M, particle size (50% by volume) = 20 microns, isostatic crush strength: test pressure 16000 psi, true density (g / cc) = 0.46.

[0204] - hollow glass beads D4: 3M TM K1 Glass Bubbles®, sold by the company 3M, particle size (50% by volume microns) = 65 microns, isostatic crush strength: test pressure 250 psi, true density (g / cc) = 0.125. ​​

[0205] - Curing rate control agent G1 : 1,3,5,7-tetramethyl-1,3,5,7-tetravinyl-cyclotetrasiloxane.

[0206] - Curing rate control agent G2: 1-ethynyl-1-cyclohexanol (ECH).

[0207] - Curing rate control agent G3-MB: 90 wt% of organopolysiloxane A1 and 10 wt% of curing rate control agent G2.

[0208] - Catalyst C: 10% platinum in dimethyl vinyl dimer at 350 cS as Karstedt catalyst, sold by Johnson Matthey Company.

[0209] - Catalyst C-MB: 98 wt% of organopolysiloxane A1 and 2 wt% of catalyst C.

[0210] - Reactive diluent E = 1-tetradecene.

[0211] II) Example section I

[0212]

[0213]

[0214] Table 1 : Precursors of two-component Package 1 silicone rubber composite foam material of the present application

[0215] Component A Parts by weight Organopolysiloxane A1 78.27 Reactive diluent E 8.62 Catalyst C 0.063 Hollow glass beads D1 13.05 Component B Organopolysiloxane A1 69.23 Organopolysiloxane B2 (XL) 2.46 Organopolysiloxane B1 (CE) 15.26 Cure rate control agent G1 0.0029 Hollow glass beads D1 13.05

[0216] Table 2: Precursors of two-component Package 2 silicone rubber composite foam material of the present application.

[0217] - For two-component Package 1, components A and B were combined in a 6:1 w / w (weight ratio) before curing to produce composition I.

[0218] - For two-component Package 2, components A and B were combined in a 1 :1 w / w (weight ratio) before curing to produce composition II.

[0219] Each Package 1 and 2 was poured into a battery module housing 102, inside which a plurality of battery cells 103 electrically connected to each other were arranged, before curing. Curing took place at room temperature to produce a silicone rubber composite foam material comprising silicone rubber binder and hollow glass beads, which completely filled the open spaces of the battery module housing 102 and completely covered the battery cells 103.

[0220] III) Example section II

[0221] The following packages were prepared:

[0222]

[0223]

[0224] Table 3. Formulation 3 - Comparative

[0225] Component A Percent by weight Organopolysiloxane A1 83.6900％ Catalyst C 0.0335％ Hollow glass beads D2 16.2800％ Total 100.0035％ Component B Percent by weight Organopolysiloxane A1 65.21％ Organopolysiloxane B1 (CE) 16.69％ Organopolysiloxane B2 (XL) 1.82％ Hollow glass beads D2 16.28％ Total 100.00％

[0226] Table 4. Formulation 4 - Invention

[0227]

[0228]

[0229] Table 5. Formulation 5 - Invention

[0230] Component A Percent by weight Organopolysiloxane A1 80.8380％ Catalyst C 0.1620％ Hollow glass beads D2 19.0000％ Total 100.0000％ Component B Percent by weight Organopolysiloxane A1 63.2407％ Organopolysiloxane B1 (CE) 15.8396％ Organopolysiloxane B2 (XL) 1.9188％ Cure rate control agent G2 0.0010％ Hollow glass beads D2 19.0000％ Total 100.0000％

[0231] Table 6. Formulation 6 - Invention

[0232]

[0233]

[0234] Table 7. Formulation 7 - Invention

[0235]

[0236] Table 8: Formulations 8, 9 and 10 (Invention), (H as SiH) / vinyl molar ratio = 0.72

[0237]

[0238]

[0239] Table 9: Formulations 11, 12 and 13 (Invention) - (H as SiH) / vinyl molar ratio = 0.72

[0240]

[0241] Table 10: Formulations 14, 15 and 16 (Invention) - (H as SiH) / vinyl molar ratio = 0.72

[0242] - Formulation 3 was mixed at 1 : 1 mixing weight ratio and cured at room temperature (25°C) overnight for 16 hours to produce a cured silicone elastomer (silicone rubber composite foam).

[0243] - Mixing ingredients 4-16 in a 1 : 1 mixing weight ratio and curing at room temperature (25°C) overnight for 16 hours to produce a silicone rubber composite foam material according to the application.

[0244] - Preparing an ingredient 17 (comparative) by mixing in a 1 : 1 mixing weight ratio two-part components sold by Elkem Silicones under the name RTV-3040 (two-part component, polyaddition curing system) and curing at room temperature (25°C) overnight for 16 hours to produce a cured silicone elastomer.

[0245] - Preparing an ingredient 18 (comparative) by mixing in a 1 : 1 mixing weight ratio two-part components sold by Elkem Silicones under the name Bluesil TM ESA 7242 (is a two-component heat-cured liquid silicone elastomer which crosslinks by polyaddition) and curing at room temperature (25°C) overnight for 16 hours to produce a cured silicone elastomer.

[0246] - Ingredient 19 has been prepared based on Sakrete Concrete. The concrete used comes from SAKRETE of North America, LLC located in Charlotte, North Carolina. The product is called SAKRETE High Strength Concrete Mix. This concrete sample was prepared using the following method:

[0247] Pour 1 kg of high strength concrete mix into a container, creating a well in the center of the concrete.

[0248] Add enough water to obtain a workable mix (70 g).

[0249] Pour the material into a 51 mm diameter mold.

[0250] Add the material to the void and then level with a metal trowel.

[0251] Allow the material to harden until a thumbprint will not leave in the material.

[0252] Use a metal trowel while the material is hardening to obtain the desired finish and flatness.

[0253] Keep the material moist and under plastic for 7 days while constantly kept at room temperature.

[0254]

[0255] Table 11. Physical Properties (NA) of Cured Products (Composite Silicone Foam Material): "Not Available"

[0256]

[0257]

[0258] Table 12. Measurement of thermal conductivity of cured samples.

[0259] Thermal conductivity was measured using a Thermtes t Hot Di sk TPS (Transient Plane Source) 2500S tester and is shown in Table 12. Table 12 shows that the thermal conductivity of the ingredients (ingredients 4-16) according to the embodiments of the present invention is lower than that of the comparative materials: ingredient 17 (RTV3040), ingredient 18 (ESA7242), ingredient 19 (Sakrete concrete), and ingredient 3 (ESA7200).

[0260] One advantage is the presence of thermal insulation material. If the batteries or multiple batteries in the battery pack overheat, the insulation material surrounding the batteries will help prevent excessive heat from reaching the passenger area of ​​electric vehicles (cars, trucks, boats, trains, airplanes, etc.).

[0261] Another advantage of the cured formulations 4-16 according to the invention is their ability to absorb vibration. Resilience is related to vibration. The greater the resilience of a material, the greater the vibration transmitted through the material. Use The SRI-type rebound hammer (commonly known as a Bayshore rebound hammer) is used to quickly and accurately measure the "Rubber Properties - Vertical Rebound" as described in ASTM D2632. The rebound of the materials according to embodiments of the invention and comparative materials was measured, and the results are disclosed in Table 13. All ingredients were mixed in a 1:1 weight ratio and cured overnight at room temperature for 16 hours. A counterweight was dropped onto the test sample, and the rebound was higher than the test sample upon impact. The higher the rebound when the counterweight hits the sample, the greater its resilience. When the counterweight does not produce a high rebound, the material has low resilience.

[0262]

[0263]

[0264] Table 13. Resilience measurements of some cured products.

[0265] Table 13 shows that the comparative formulation has higher resilience and will more easily transmit vibrations through the material, while the cured formulation according to the invention has lower resilience.

[0266] "Tan delta" is the abbreviation for the term "tangent delta". Tan delta quantifies the way a material absorbs and disperses energy. It expresses the out-of-phase time relationship between the impact force and the resulting force transmitted into the support. Tan delta is also known as the loss factor, due to this loss of energy from the impact force through conversion into a safer form of energy and its dispersion. Tan delta is therefore ultimately an indication of the effectiveness of the damping ability of the material. The higher the tan delta, the greater the damping coefficient, the more effectively the material will perform in energy absorption and dispersion. Tan delta is equal to the ratio of the loss modulus to the storage modulus or tan (delta) = G" / G'.

[0267] G" = loss modulus and G' = storage modulus. Higher values relate to more effective materials than those with lower values.

[0268] Table 14 below shows examples where the damping properties of the inventive material are superior to comparative materials.

[0269]

[0270]

[0271] Table 14. Tan delta measurements of some cured products.

[0272] Tan delta measurements were performed using an Anton Parr MCR 302 at 25 °C. G" and G' were measured at the time of curing of the material. Tan delta was calculated from these two values. Cured samples of silicone composite foam materials prepared from the addition-cured organopolysiloxane composition according to a preferred embodiment of the present application can advantageously be used as damping materials and meet the goals required in the field of electric vehicles, which desire damping control strategies to minimize powertrain vibrations.

[0273] The flame retardancy of 3 cured materials according to the present application was measured and is shown in Table 15. All test formulations were self-extinguishing.

[0274]

[0275] Table 15. Flame retardancy results of some cured materials according to the present application.

[0276] IV) Example section III

[0277]

[0278]

[0279] Table 16. Formulation 20 - present application

[0280] A silicone rubber composite foam was prepared using formulation 20 (an addition cure organic polysiloxane composition) and compared to a silicone rubber composite foam prepared from formulation 21 (a tin catalyzed condensation cure product). The ingredients are described in Tables 16 and 17, respectively.

[0281]

[0282] Table 17. Formulation 21 - Condensation Cured Silicone Rubber Composite Foam

[0283] A battery pack can have a long distance, i.e. the distance that the insulating material (a liquid precursor prior to crosslinking of the silicone composite foam according to the present invention) needs to travel from the outside air when filling the battery pack. The comparative formulation 21 described above requires moisture from the air to cure quickly. The formulation was mixed at 25°C and allowed to sit at that temperature until it cured enough to take an initial durometer reading. A condensation curable comparative formulation 21 was also made and allowed to sit in the same manner as the inventive formulation 20. Two samples were made and then allowed to sit after being poured into an aluminum pan having 1 cm thickness and 5.2 cm diameter of material. One 5.2 cm face of the material was exposed to air and no air (or moisture from the air) could move through the bottom or sides of the aluminum pan. This configuration is a representative situation that can occur in a typical battery pack. Air with moisture can be present on one face of the potting material for the battery while the bulk of the material below that surface relies on moisture migration through the block of potting material.

[0284] With respect to the inventive formulation 20, it took about 12 minutes to be able to measure the hardness of the material in the Shore A range. The durometer was about 15 Shore A. At 1 hour the durometer was 50 Shore A. Similar formulations in the previous examples reached about 52-54 Shore A. When examining the condensation curable formulation 21, it took 1 hour and 42 minutes before a durometer measurement could be made and the value was 11.7 Shore A. When the sample was pressed by hand and then the second sample (counterpart in the pan) was pulled away, it was found that the bottom half of the sample was still liquid. The curing occurred only in the top layer of the test sample. This indicates that the condensation cured material requires significantly longer time to cure in a representative test configuration compared to the inventive formulation. It would be advantageous if the material cured more quickly when potting a battery pack to speed up production time.

[0285] Another cure system was tested: a peroxide cure system. However, peroxides typically require heat to cure, so this is not advantageous. As shown above, the inventive formulation 11 can cure very quickly if desired and does not require heat or energy converted to heat.

[0286] One peroxide comparative formulation 22 is described below in Table 18:

[0287] Component A Percent by weight Hollow glass beads D2 15.84％ Organopolysiloxane A2 84.16％ Total 100.00％ Component B Percent by weight Hollow glass beads D2 15.84％ Organopolysiloxane A2 62.54％ Organopolysiloxane A3 21.02％ DBPH* 0.61％ Total 100.01％

[0288] Table 18. Formulation 22 - peroxide cured comparative formulation 22 and components A and B are mixed in a 1 : 1 weight ratio

[0289] and sold by R.T. Vanderbilt

[0290] • Organopolysiloxane A3: poly(methyl vinyl)(dimethyl)siloxane with dimethyl vinyl silyl end units, viscosity = 390 mPa.s at 25°C;

[0291] Class and Grasso suggest curing silicone at 177°C for 1 hour with DBPH catalyst (reference: Class, J.B.; Grasso, R.P., The Efficiency of Peroxides for Curing Silicone Elastomers, Rubber Chemistry and Technology, September 1993, Vol. 66, No. 4, pp. 605-622). We also followed this recommendation for curing our formulations. No post-cure was performed.

[0292] The same type of container was used to hold the material during curing (aluminum pan, one open face, 5.2 cm diameter and 1 cm thickness of poured material). We kept one face open because when pouring is performed, material is usually poured into the container and cured exposed to air. Placing a lid on the container to isolate air would be an additional cost of the lid and additional time to attach the lid in a production device. When cured at 177°C for 1 hour, the sample was removed from the oven. The face exposed to air was uncured. This is not an unusual phenomenon, but tests were performed in these formulations to see if a formulation similar to the present formulation would have the problem observed in other peroxide cured silicone formulations. Once the uncured layer was removed, the durometer of the cured peroxide comparative elastomer formulation 22 was 20 Shore A.

[0293] Three ways are commonly used in industry to eliminate the problem of lack of cure at the oxygen containing interface:

[0294] • Removing oxygen from the cure zone by using an inert gas, by using a wax that migrates to the surface and forms a barrier, or by using a film that directly contacts the coating.

[0295] • Increasing the radical concentration by increasing the peroxide level. ​

[0296] • use of chemicals that react with peroxide radicals.

[0297] All these solutions for undercure are viable. However, heating of the sample is still required and implementation of the solution will require significantly more complex ingredients (which alter the cured elastomer, i.e. waxes, chemicals that react with peroxide radicals, etc.) and more expensive ingredients (i.e. more free radical peroxides).

[0298] IV) Example section III

[0299] Formulations 23-27 were prepared according to Table 19. Thermal conductivity (W / mK) and specific gravity (g / cm3) were measured. 3 Thermal conductivity was measured using a Thermtest Hot Disk TPS (Transient Plane Source) 2500S tester.

[0300]

[0301]

[0302] Table 19 - Formulations 23, 24, 25, 26 and 27.

[0303] Embodiment

[0304] The present invention provides the following embodiments:

[0305] 1. A secondary battery pack comprising:

[0306] - at least one battery module housing 102 in which a plurality of battery cells 103 electrically connected to each other are arranged,

[0307] - a silicone rubber composite foam material comprising a silicone rubber binder and hollow glass beads, and said silicone rubber composite foam material partially or completely fills the open space of said battery module housing 102 and / or partially or completely covers said battery cells 103 and / or partially or completely covers said module housing 102, and

[0308] - an optional lid covering the battery module housing 102.

[0309] 2. The secondary battery pack according to embodiment 1, wherein the battery cells 103 are of lithium ion type.

[0310] 3. The secondary battery pack according to embodiment 1, wherein said silicone rubber composite foam material is obtained by curing an addition-curing type organopolysiloxane composition X.

[0311] 4. The secondary battery pack according to Embodiment 1, further comprising a plurality of heat dissipating elements located at two or more interfaces between the battery cells, and comprising at least one heat exchanging element integrated with the heat dissipating elements, which is mounted on one side of the battery module housing 102, whereby the heat generated by the battery cells during charging and discharging of the battery cells is removed through the heat exchanging element.

[0312] 5. The secondary battery pack according to Embodiment 4, wherein the heat dissipating elements are made of a thermally conductive material exhibiting high thermal conductivity, and the heat exchanging element has one or more coolant channels to allow a coolant, such as a liquid or a gas, to flow therein.

[0313] 6. The secondary battery pack according to Embodiment 1, wherein the hollow glass beads are hollow borosilicate glass microspheres.

[0314] 7. The secondary battery pack according to Embodiment 6, wherein the hollow borosilicate glass microspheres have a true density of 0.10 gram per cubic centimeter to 0.65 gram per cubic centimeter.

[0315] 8. The secondary battery pack according to Embodiment 1, wherein the hollow glass beads are present up to a volume loading of 80% in the silicone rubber composite foam material, and preferably are present in a volume loading of 5% to 70% of the silicone rubber composite foam material.

[0316] 9. The secondary battery pack according to Embodiment 1, wherein the silicone rubber composite foam material is used as a potting material located within the battery module housing 102 to at least partially enclose the plurality of battery cells 103 and / or located outside the battery module housing 102 to at least partially enclose the battery module housing 102.

[0317] 10. The secondary battery pack according to Embodiment 3, wherein the addition-cure type organopolysiloxane composition X comprises:

[0318] a) at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing 2 to 14 carbon atoms, preferably said alkenyl groups are selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups,

[0319] b) at least one silicon compound B having at least two and preferably at least three hydrogen atoms bonded to silicon per molecule,

[0320] c) hollow glass beads D, and preferably hollow borosilicate glass microspheres,

[0321] d) a hydrosilylation catalyst C,

[0322] e) optionally at least one cure rate control agent G which slows the cure rate,

[0323] f) optionally at least one reactive diluent E which reacts by hydrosilylation,

[0324] g) optionally at least one additive H such as pigments, dyes, clays, surfactants, hydrogenated castor oil, wollastonite, aluminum trihydrate, magnesium hydroxide, talc, huntite, hydro-magnesite, exfoliated graphite, zinc borate, mica or fumed silica.

[0325] 11. A process for preparing a secondary battery pack as defined in embodiment 3 or 10 comprising the steps of:

[0326] a) preparing at least one battery module housing 102 in which a plurality of battery cells 103 are arranged which are electrically connected to each other,

[0327] b) introducing into said battery module housing 102 an addition-cure type organopolysiloxane composition X as defined in embodiment 3 or 11,

[0328] c) completely or partially filling said battery module housing 102, and

[0329] d) allowing curing to take place to form a silicone rubber composite foam material comprising a silicone rubber binder and hollow glass beads, and optionally

[0330] e) covering the battery module housing 102 with a lid.

[0331] 12. The process according to embodiment 11, wherein preparing the addition-cure type organopolysiloxane composition X comprises the steps of:

[0332] a) feeding into a base feed line a liquid silicone base MS1 comprising:

[0333] i) at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing 2 to 14 carbon atoms, preferably said alkenyl groups are selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups,

[0334] ii) hollow glass beads D, and preferably hollow borosilicate glass microspheres D1,

[0335] iii) at least one silicon compound B having at least two and preferably at least three hydrogen atoms bonded to silicon per molecule, and

[0336] iv) optionally a cure rate control agent G which slows down the cure rate,

[0337] b) feeding into a catalyst feed line a catalyst masterbatch MC comprising:

[0338] i) at least one hydrosilylation catalyst C; and

[0339] ii) optionally, at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, preferably said alkenyl groups are selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups;

[0340] c) feeding an inhibitor masterbatch Ml comprising:

[0341] i) a cure rate control agent G that slows the cure rate; and

[0342] ii) optionally, at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, preferably said alkenyl groups are selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups; and

[0343] d) optionally feeding an additive masterbatch MA comprising:

[0344] i) at least one additive H such as a pigment, a dye, a clay, a surfactant, a hydrogenated castor oil, a wollastonite, an aluminum trihydrate, a magnesium hydroxide, a halloysite, a huntite, a hydromagnesite, an exfoliated graphite, a zinc borate, a mica or a fumed silica, and

[0345] ii) optionally, at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, preferably said alkenyl groups are selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups; and

[0346] e) introducing said liquid silicone base MS1, said catalyst masterbatch MC and said inhibitor masterbatch Ml and optionally said additive masterbatch MA into a tank to obtain an addition-cure type organopolysiloxane composition X.

[0347] 13. The method according to embodiment 11, wherein the addition-cure type organopolysiloxane composition X is prepared comprising the steps of:

[0348] a) feeding a base feed line with a liquid silicone base MS2 comprising:

[0349] i) at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, preferably said alkenyl groups are selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups, and

[0350] ii) at least one silicon compound B having at least two and preferably at least three hydrogen atoms bonded to silicon per molecule,

[0351] iii) optionally a cure rate control agent G which slows the cure rate,

[0352] b) feeding into the catalyst feed line a catalyst masterbatch MC comprising:

[0353] i) at least one hydrosilylation catalyst C; and

[0354] ii) optionally, at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, preferably said alkenyl groups are selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups;

[0355] c) feeding into the inhibitor feed line an inhibitor masterbatch Mi comprising:

[0356] i) a cure rate control agent G which slows the cure rate; and

[0357] ii) optionally, at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, preferably said alkenyl groups are selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups; and

[0358] d) optionally feeding into the additive feed line an additive masterbatch MA comprising:

[0359] i) at least one additive H such as a pigment, a dye, a clay, a surfactant, a hydrogenated castor oil, a wollastonite, an aluminum trihydrate, a magnesium hydroxide, a halloysite, a huntite, a hydromagnesite, an exfoliated graphite, a zinc borate, a mica or a fumed silica, and

[0360] ii) optionally at least one organopolysiloxane A having at least two alkenyl groups bonded to silicon per molecule, said alkenyl groups each containing from 2 to 14 carbon atoms, preferably said alkenyl groups are selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, and most preferably said alkenyl groups are vinyl groups;

[0361] e) introducing said liquid silicone base MS2, said catalyst masterbatch MC and said inhibitor masterbatch Ml and optionally said additive masterbatch MA into an agitated tank; and

[0362] f) operating said agitated tank, thereby mixing said liquid silicone base MS1, said catalyst masterbatch MC and said inhibitor masterbatch Ml and optionally said additive masterbatch MA, preferably by using a high flow, low shear mixer, and

[0363] g) adding hollow glass beads D and preferably hollow borosilicate glass microspheres Dl to said agitated tank, preferably by using a gravity discharge or screw feeder, to obtain an addition-cure type organopolysiloxane composition X.

[0364] 14. The secondary battery pack according to embodiment 1, which is located in a vehicle.

[0365] 15. The secondary battery pack according to embodiment 1, which is located in an automotive engine vehicle.

[0366] 16. The secondary battery pack according to embodiment 1, which is located in an all-electric vehicle (EV), a plug-in hybrid electric vehicle (PHEV), a hybrid electric vehicle (HEV).

[0367] 17. The secondary battery pack according to embodiment 1, which is located in: an airplane, a small boat, a ship, a train or a combined cabinet.

Claims

1. A system for preparing a silicone rubber composite foam material, wherein the silicone rubber composite foam material comprises hollow glass beads D, the system comprising: (i) an organopolysiloxane A, each molecule of which has at least two alkenyl groups bonded to silicon, each alkenyl group containing 2-14 carbon atoms, wherein the viscosity of the organopolysiloxane A at 25°C is from 5 mPa·s to 5000 mPa·s; (ii) Silicon compound B, which includes: (a) A silicon chain extender B1, wherein each molecule has two distally chelated hydrogen atoms bonded to silicon and each molecule has no side-bonded hydrogen atoms bonded to silicon, wherein the viscosity of said silicon chain extender B1 at 25°C is from 5 mPa·s to 100 mPa·s; and (b) Silicon crosslinking agent B2, wherein each molecule has at least three hydrogen atoms bonded to silicon, wherein the viscosity of said silicon crosslinking agent B2 at 25°C is from 5 mPa·s to 2000 mPa·s; (iii) Hydrogenated silanization catalyst C; (iv) at least one curing rate control agent G, which slows down the curing rate of the silicone foam system; and (v) Optional at least one additive H, wherein the additive H optionally includes pigments, dyes, clays, surfactants, hydrogenated castor oil, wollastonite, aluminum trihydrate, magnesium hydroxide, pyrite, calcium magnesium carbonate, hydromagnesia, expanded graphite, zinc borate, mica and / or fumed silica. The weight ratio of the organopolysiloxane A(i) and the silicon compound B(ii) is such that the overall molar ratio of hydrogen atoms bonded to silicon to all alkenes bonded to silicon is 0.4 to 1.5; and When the system contains 9% to 20% by weight of hollow glass beads D, the viscosity of the system at 25°C is 500 mPa·s to 5000 mPa·s, and it is capable of filling the battery module housing.

2. The system according to claim 1, wherein when the system contains 9% to 20% by weight of hollow glass beads D, the viscosity of the system at 25°C is 500 mPa·s to 2500 mPa·s.

3. The system according to claim 1 or 2, wherein when cured in the presence of the hollow glass beads D, the system provides a flame-retardant silicone rubber composite foam material.

4. The system according to claim 1, wherein the weight ratio of silicon chain extender B1 to silicon crosslinker B2 of the silicon compound B(ii) is 6.2:1 to 11.2:

1.

5. The system according to claim 1, wherein the weight ratio of silicon chain extender B1 to silicon crosslinker B2 of the silicon compound B(ii) is from 6.2:1 to 10.8:

1.

6. The system according to claim 1, wherein the weight ratio of silicon chain extender B1 to silicon crosslinker B2 of the silicon compound B(ii) is 6.2:1 to 8.9:

1.

7. The system according to claim 1, wherein each molecule of the organopolysiloxane A has at least two alkenyl groups bonded to silicon selected from vinyl, allyl, hexenyl, decenyl, tetradecenyl, and combinations thereof.

8. The system according to claim 1, wherein the hydrogenation silanization catalyst C is selected from platinum-based catalysts, rhodium-based catalysts, ruthenium-based catalysts, palladium-based catalysts, nickel-based catalysts, and combinations thereof.

9. The system of claim 8, wherein the platinum-based catalyst comprises a Karstedt catalyst.

10. The system according to claim 1, wherein the curing rate control agent G is selected from alkynyl alcohols, heterocyclic amines, alkyl maleates, alkene siloxanes, and combinations thereof.

11. The system of claim 10, wherein the olefinic siloxane comprises vinyl-containing cyclosiloxanes and vinyl-containing polydiorganosiloxanes.

12. A system for preparing a silicone rubber composite foam material, wherein the silicone rubber composite foam material comprises hollow glass beads D, the system comprising: (i) an organopolysiloxane A, each molecule of which has at least two alkenyl groups bonded to silicon, each alkenyl group containing 2-14 carbon atoms, and wherein the viscosity of the organopolysiloxane A at 25°C is from 5 mPa·s to 5000 mPa·s. (ii) Silicon compound B, which includes: (a) Silicon chain extender B1, wherein each molecule has two distally chelated hydrogen atoms bonded to silicon and each molecule has no side-bonded hydrogen atoms bonded to silicon, wherein the viscosity of said silicon chain extender B1 at 25°C is from 5 mPa·s to 100 mPa·s; and (b) Silicon crosslinking agent B2, wherein each molecule has at least three hydrogen atoms bonded to silicon, wherein the viscosity of said silicon crosslinking agent B2 at 25°C is from 5 mPa·s to 2000 mPa·s; (iii) Hydrogenated silanization catalyst C; and (iv) At least one curing rate control agent G, which slows down the curing rate of the silicone foam system; The weight ratio of the organopolysiloxane A(i) and the silicon compound B(ii) is such that the overall molar ratio of hydrogen atoms bonded to silicon to all alkenes bonded to silicon is 0.4 to 1.5; and When the system contains 9% to 20% by weight of hollow glass beads D, the viscosity of the system at 25°C is 500 mPa·s to 5000 mPa·s, and it is capable of filling the battery module housing.

13. The system according to claim 12, wherein when the system contains 9% to 20% by weight of hollow glass beads D, the viscosity of the system at 25°C is 500 mPa·s to 2500 mPa·s.

14. The system of claim 12 or 13, wherein, upon curing, the system provides a flame-retardant silicone rubber composite foam material.

15. The system according to claim 12, wherein the weight ratio of silicon chain extender B1 to silicon crosslinker B2 of the silicon compound B(ii) is from 6.2:1 to 11.2:

1.

16. The system of claim 12, wherein the weight ratio of silicon chain extender B1 to silicon crosslinker B2 of the silicon compound B(ii) is from 6.2:1 to 10.8:

1.

17. The system according to claim 12, wherein the weight ratio of silicon chain extender B1 to silicon crosslinker B2 of the silicon compound B(ii) is from 6.2:1 to 8.9:

1.

18. The system of claim 12, wherein each molecule of the organopolysiloxane A has at least two alkenyl groups bonded to silicon selected from vinyl, allyl, hexenyl, decenyl, tetradecenyl, and combinations thereof.

19. The system of claim 12, wherein the hydrogenation silanization catalyst C is selected from platinum-based catalysts, rhodium-based catalysts, ruthenium-based catalysts, palladium-based catalysts, nickel-based catalysts, and combinations thereof.

20. The system of claim 19, wherein the platinum-based catalyst comprises a Karstedt catalyst.

21. The system of claim 12, wherein the curing rate control agent G is selected from alkynyl alcohols, heterocyclic amines, alkyl maleates, alkene siloxanes, and combinations thereof.

22. The system of claim 21, wherein the olefinic siloxane comprises vinyl-containing cyclosiloxanes and vinyl-containing polydiorganosiloxanes.

23. A packaging system for preparing a silicone rubber composite foam material, wherein the silicone rubber composite foam material comprises hollow glass beads D, and the packaging system comprises two packages: The first package P1 includes: 100 parts by weight of organopolysiloxane A, and Based on platinum-based hydrosilylation catalyst C, with a concentration of 4-150 ppm (calculated as platinum metal); and The second package P2 includes: 100 parts by weight of organopolysiloxane A, 10 to 70 parts by weight of silicon chain extender B1, 5 to 25 parts by weight of silicone crosslinking agent B2, and An effective amount of at least one curing rate control agent G, which slows down the curing rate; (i) wherein each molecule of the organopolysiloxane A has at least two alkenyl groups bonded to silicon, each alkenyl group containing 2-14 carbon atoms, and wherein the viscosity of the organosiloxane A at 25°C is from 5 mPa·s to 5000 mPa·s. (ii) wherein each molecule of the silicon chain extender B1 has two distally chelated hydrogen atoms bonded to silicon and no side-bonded hydrogen atoms bonded to silicon, and has a viscosity of 5 mPa·s to 100 mPa·s at 25°C; and (iii) wherein each molecule of the silicon crosslinking agent B2 has at least three hydrogen atoms bonded to silicon, and the viscosity at 25°C is from 5 mPa·s to 2000 mPa·s; The weight ratio of the organopolysiloxane A, the silicon chain extender B1, and the silicon crosslinking agent B2 is such that the overall molar ratio of hydrogen atoms bonded to silicon to all alkenes bonded to silicon is 0.4 to 1.5; and When 9% to 20% by weight of hollow glass beads D are included in at least one of packages P1 and P2, the combination of P1 and P2 provides a composition with a viscosity of 500 mPa·s to 5000 mPa·s at 25°C and is capable of filling the battery module housing.

24. The packaging system according to claim 23, wherein when 9% to 20% by weight of hollow glass beads D are included in at least one of packages P1 and P2, the combination of P1 and P2 provides a composition with a viscosity of 500 mPa·s to 2500 mPa·s at 25°C.

25. The packaging system according to claim 23 or 24, wherein the prepared silicone rubber composite foam material is flame retardant.

26. The packaging system of claim 23, wherein the weight ratio of the silicon chain extender B1 to the silicon crosslinker B2 is from 6.2:1 to 11.2:

1.

27. The packaging system of claim 23, wherein the weight ratio of the silicon chain extender B1 to the silicon crosslinker B2 is from 6.2:1 to 10.8:

1.

28. The packaging system of claim 23, wherein the weight ratio of the silicon chain extender B1 to the silicon crosslinker B2 is from 6.2:1 to 8.9:

1.

29. The packaging system of claim 23, wherein each molecule of the organopolysiloxane A has at least two alkenyl groups bonded to silicon selected from vinyl, allyl, hexenyl, decenyl, tetradecenyl, and combinations thereof.

30. The packaging system of claim 23, wherein the hydrogenation silanization catalyst C is selected from platinum-based catalysts, rhodium-based catalysts, ruthenium-based catalysts, palladium-based catalysts, nickel-based catalysts, and combinations thereof.

31. The packaging system of claim 30, wherein the platinum-based catalyst comprises a Karstedt catalyst.

32. The packaging system of claim 23, wherein the curing rate control agent G is selected from alkynyl alcohols, heterocyclic amines, alkyl maleates, alkene siloxanes, and combinations thereof.

33. The packaging system of claim 32, wherein the olefinic siloxane comprises cyclosiloxanes containing vinyl groups and polydiorganosiloxanes containing vinyl groups.

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