CN117897842A

CN117897842A - Secondary battery pack with improved thermal management

Info

Publication number: CN117897842A
Application number: CN202280055294.0A
Authority: CN
Inventors: K·E·梅斯纳; 孟岩; J·安波杰; M·基哈拉; S·杰克逊; V·奥尼尔
Original assignee: Elkem Silicones USA Corp
Current assignee: Elkem Silicones USA Corp
Priority date: 2021-08-13
Filing date: 2022-08-11
Publication date: 2024-04-16

Abstract

The present invention relates to a novel secondary battery pack with improved thermal management that can be used in electric-only vehicles (EVs), plug-in hybrid vehicles (PHEVs), hybrid vehicles (HEVs), or battery packs for other vehicle batteries, and more particularly to the use of specific materials for thermally insulating secondary battery packs and further minimizing the propagation of thermal runaway within the battery pack.

Description

Secondary battery pack with improved thermal management

Cross-reference to related patent applications

This patent application claims priority from U.S. provisional patent application Ser. No. 63/335,043, U.S. provisional patent application Ser. No. 63/233,057, U.S. provisional patent application Ser. No. 63/314,224, U.S. provisional patent application Ser. No. 63/233,057, and U.S. provisional patent application Ser. No. 63/314,224, U.S. provisional patent application Ser. No. 25, 2, 2022, filed 26, 4, 2021, each of which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates to novel secondary batteries, particularly those containing lithium ion battery cells, having improved thermal management, allowing long term use under extreme temperature conditions. More particularly, the present invention relates to the use of specific isocyanate-based materials (polyurethanes, polyureas, polyisocyanurates and mixtures thereof) for thermally insulating secondary batteries and further minimizing the propagation of thermal runaway within the batteries. The secondary battery pack may be used in an Electric Vehicle (EV), a plug-in hybrid vehicle (PHEV), a hybrid vehicle (HEV), or in other vehicle batteries.

Background

Batteries can be broadly classified into primary batteries and secondary batteries. Primary batteries, also known as disposable batteries, are intended to be spent, after which they are simply replaced with one or more new batteries. Secondary batteries, more commonly referred to as rechargeable batteries, are capable of being repeatedly recharged and reused, thus providing economic, environmental and ease of use benefits over disposable batteries. Examples of the secondary battery may include a nickel-cadmium battery, a nickel-metal hybrid battery, a nickel-hydrogen battery, a lithium secondary battery, and the like.

Secondary batteries, particularly lithium ion batteries, have emerged as a key energy storage technology and are now the primary technology for consumer electronics, industrial, transportation, and energy storage applications.

Due to its high potential, high energy and power density, and good lifetime, secondary batteries are now the preferred battery technology, particularly in the automotive industry, because they can now provide longer driving range and suitable acceleration for electric vehicles such as hybrid vehicles (HEVs), battery powered vehicles (BEVs), and plug-in hybrid vehicles (PHEVs). In the current automotive industry, lithium ion battery cells of different sizes and shapes are manufactured and then assembled into packages of different configurations. Automotive secondary batteries are typically composed of many (sometimes hundreds or even thousands) of battery cells to meet the required power and capacitance requirements.

However, this conversion is not without technical hurdles in drive system technology, as the use of electric motors means that inexpensive batteries with high energy density, long operating life and operating capability under a variety of conditions are required. While rechargeable battery cells offer many advantages over disposable batteries, this type of battery is not without drawbacks.

In general, most of the drawbacks associated with rechargeable batteries are due to the battery chemicals used, as these chemicals tend not to be as stable as those used in primary batteries. Under typical power/current loads and ambient operating conditions, the temperature within most lithium ion battery cells is maintained at 20 ℃ to 55 ℃ by thermal management system control. However, adverse conditions such as high power consumption at high cell temperatures, chemical disablement within individual cells, may increase localized heat generation. Specifically, above the critical temperature, the exothermic chemical reaction within the battery cell is activated and the heat generated becomes far more than the heat extracted by the thermal management system. Now, this phenomenon, called "thermal runaway", generally refers to a sudden rapid increase in the temperature and pressure of the battery cells due to various operating factors, which results in the spread of excessive temperatures throughout the battery module. Thermal runaway can lead to cell emptying and internal temperatures exceeding 200 ℃. In the lithium ion battery thermal runaway test, it has been reported that the maximum cell surface temperature of a fully charged cylindrical 18650 type lithium ion battery is 310 ℃ to 870 ℃. It is also reported that the flame temperature of the individual battery cells measured is as high as 1060 ℃ and that the flame temperature of the battery module containing a group of battery cells is 1500 ℃. As a result, power from the battery pack is interrupted and systems using the battery pack are more likely to suffer extensive collateral damage due to the scale of damage and the associated release of thermal energy.

As the temperature of the battery cells that have undergone such a temperature increase, the temperature of adjacent battery cells in the battery pack will also increase. If the temperatures of these adjacent cells are allowed to rise unimpeded, they may also enter an unacceptable state of extremely high temperature within the cells, resulting in a cascading effect in which the temperature rise within the individual cells begins to propagate throughout the battery pack.

In addition, due to the characteristics of the lithium ion battery, the secondary battery pack operates in an ambient temperature range of-20 to 60 ℃. However, even when operating in this temperature range, the secondary battery pack may start to lose its capacity or charge-discharge capability (if the ambient temperature drops below 0 ℃). Depending on the ambient temperature, the life cycle capacitance or charge-discharge capability of the battery can be greatly reduced when the temperature is below 0 ℃. Nevertheless, the use of lithium ion batteries is unavoidable in cases where the ambient temperature falls outside the optimal ambient temperature range (20 ℃ to 25 ℃). These factors not only greatly shorten the driving range of the vehicle, but also cause great damage to the battery. The degradation of energy and power available at lower temperatures is due to a decrease in capacitance and an increase in internal resistance.

In summary, in a battery pack or battery module having a plurality of battery cells, a significant temperature change may occur from one battery cell to the next, which is detrimental to the performance of the battery pack. To promote long life of the entire battery, the battery temperature must be below a desired threshold temperature. In order to improve the performance of the battery pack, the temperature difference between the batteries in the secondary battery pack should be minimized. However, depending on the thermal path to the environment, different cells will reach different temperatures. Furthermore, for the same reason, different batteries reach different temperatures during the charging process. Therefore, if one battery cell is at an elevated temperature relative to the other battery cells, its charge-discharge efficiency will be different, and thus, it may charge-discharge faster than the other batteries. This will result in a decrease in the performance of the entire secondary battery pack.

Several approaches have been taken to reduce the risk of thermal problems or to reduce the risk of thermal propagation. These can be found in U.S. patent B-8,367,233, which discloses a battery thermal management system that includes at least one enclosure fault port integrated into at least one wall of the battery enclosure, wherein the enclosure fault port remains closed during normal operation of the battery and opens during a thermal event of the battery, thereby providing a flow path to vent hot gases generated during the thermal event from the battery enclosure in a controlled manner.

Another approach is to develop new cell chemistries and/or modify existing cell chemistries. Yet another approach is to provide additional shielding at the cell level, thereby inhibiting the flow propagation of thermal energy from cells experiencing thermal management problems to adjacent cells. Yet another approach is to use a spacer assembly to maintain the position of the cells experiencing a thermal event at their predetermined locations within the battery pack, thereby helping to minimize thermal effects on adjacent cells.

Thermal insulation of the battery has also been described to reduce the risk of thermal diffusion or their propagation. For example, document US-se:Sup>A-2007/0259258 describes se:Sup>A lithium generator cell in which the generators are placed on top of each other and this stack is held in place by se:Sup>A polyurethane foam encasement. An embodiment is also disclosed in which cooling fins are inserted between the two generators.

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

Document US-se:Sup>A-2012/0003508 describes se:Sup>A battery of se:Sup>A lithium electrochemical generator, comprising se:Sup>A housing; a plurality of lithium electrochemical generators contained in the housing, each generator comprising a container; a rigid flame retardant foam having closed cells formed of an electrically insulating material filling the space between the inner wall of the housing of each electrochemical generator and the free surface of the container side wall, the foam covering the free surface of the container side wall of each electrochemical generator and having a length of at least 25% of the container height. According to one embodiment, the rigid flame retardant foam consists of a material selected from the group consisting of: polyurethane, epoxy, polyethylene, melamine, polyester, polystyrene, silicone or polyurethane, and a mixture of polyurethane and epoxy is preferred. Expansion of polyurethane resins for foam formation is described, the following chemical route being used to obtain a foam:

a) CO is produced via chemical route, i.e. reaction of water with isocyanate ₂ This will cause the polyurethane to foam,

b) By physical route, i.e. evaporation of low-boiling liquids under the effect of heat generated by exothermic reaction between isocyanate and hydrogen-donor compound, or

c) Via injection of air.

While many approaches have been taken to attempt to reduce the risk of thermal attack and thermal energy transmission throughout the battery, minimizing personal and property risks is critical if battery-level thermal events do occur. As the number and size of the battery cells in a battery increases, it is also expected that the necessity and benefit of providing proper thermal management also increases.

In addition, there is a new trend in designing a battery pack that does not use a module composition, but rather builds the entire battery pack as a structural platform for a vehicle, where the battery cells help to cure the platform into one large unit. This new design reduces the complexity of the existing battery and the overall mass of the battery and thus can improve the efficiency and ultimately the mileage of the electric vehicle. With this approach, there is a strong need for thermally insulating the cell with gap filler materials that also have additional suitable structural adhesive properties. The durability of a structural adhesive (which will also function as a gap filler) depends on its ability to uniformly disperse stresses caused by vibrations generated by the road surface as the vehicle moves or to resist the impact of a vehicle bump. The performance of the structural adhesive will also depend on the modulus of the substrate and the tensile strength properties of the structural adhesive. In fact, when a load force is applied to the structural adhesive, it must exhibit good resistance to cracking under pressure. Lap shear strength is the ability of an adhesive to resist forces in the plane of the adhesive surface. The bonded structural adhesive is typically designed such that the adhesive is only subjected to forces in the plane, which creates shear stresses in the adhesive. Accordingly, there is a strong need to provide such gap filling to provide adequate structural bonding properties such as good lap shear strength and tensile strength properties, and to provide additional thermal insulation for the cells within the battery. Indeed, it is critical that the battery frame remain strong and impact resistant to protect the battery cells and more importantly the vehicle user.

In addition, due to the trend of using a gap filler having structural adhesive properties in a battery pack for a vehicle for transportation, good thermal insulation properties and low density are also required. Accordingly, battery manufacturers also desire lighter versions of such gap fillers that have structural adhesive properties, low density, and good thermal insulation properties.

In such situations, one of the basic objectives of the present invention is to provide a new battery pack that will provide proper thermal management and minimize personal and property risks due to uncontrolled thermal events, as this is still desirable. It is also required that proper thermal management is possible for the duration of the life cycle of the battery.

It is another basic object of the present invention to provide a new battery pack that will include materials that can be used for thermal insulation of the battery and/or battery pack and that have good structural bonding properties such as good lap shear strength and tensile strength properties that improve the impact resistance of the structure to protect the battery cells and, more importantly, the vehicle user.

It is another basic object of the present invention to provide such a material in a lighter form in response to the need to use lighter materials in a vehicle using a battery pack containing secondary battery cells to maximize its autonomous driving range before the battery pack needs to be recharged.

By means of the present invention, a secondary battery pack as claimed is sought that will solve the problems presented above.

All these objects are achieved, inter alia, by the present invention, which relates to a secondary battery pack 100 comprising:

a battery enclosure 101 consisting of an enclosure top plate 104 and an enclosure bottom plate 102, which when sealed to each other provide a substantially airtight battery enclosure 101,

at least one array of battery cells 103 within said housing floor 102, the batteries being electrically connected to each other and arranged in an upright manner such that the axes of the batteries are parallel to each other,

an isocyanate-based material a which partially or completely fills the open space of the battery housing 101 and/or partially or completely fills the open space within the array of battery cells 103 and/or partially or completely covers the battery cells 103,

and wherein the isocyanate-based material a is prepared by mixing and curing a composition X comprising:

(a) At least one kind of the isocyanate compound(s),

(b) At least one organic compound having at least two epoxide groups or at least one active hydrogen-containing compound or a mixture of active hydrogen-containing compounds selected from the group consisting of polyols, polyamines, polyamides, polyimides and polyalcohol amines,

(c) At least one of the catalysts is selected from the group consisting of,

(d) Optionally at least one of the blowing agents,

(e) Optionally at least one adhesion promoter, and

(f) Optionally at least one of the additives is used,

and wherein for 100 parts by weight of composition X it further comprises from 0.1 to 30 parts by weight, preferably from 0.1 to 20 parts by weight, and even more preferably from 4.5 to 30 parts by weight of at least one organopolysiloxane polymer Y comprising at least one hydroxyl-terminated polyoxyalkylene moiety as a terminal group or as a pendant group.

To achieve these objects, the applicant has compliantly, entirely surprisingly and unexpectedly demonstrated that the addition of organopolysiloxane polymer Y comprising specific hydroxyl-terminated polyoxyalkylene moieties within a formulation which is a precursor to a material such as polyurethane, polyurea, polyisocyanurate (or mixtures thereof) improves the structural adhesive properties of the material, which material can also be used as a gap filler material to thermally insulate the battery cells within a battery. The choice of materials according to the invention makes it possible to overcome the problems that are not solved by similar batteries using pure organic polyurethane materials.

In another preferred embodiment, it further comprises for 100 parts by weight of composition X from 0.1 to 25 parts by weight, preferably from 4.5 to 25 parts by weight, preferably from 1 to 15 parts by weight and preferably from 2.5 to 10 parts by weight of at least one organopolysiloxane polymer Y comprising at least one hydroxyl-terminated polyoxyalkylene moiety as a terminal group or as a pendant group.

The advantage of the material according to the invention is that it has good structural bonding properties and improved tensile strength properties as well as good lap shear strength, which is the ability of the material to resist forces in the plane of the adhesive surface, which improves the impact resistance of the structure to protect the battery cell and more importantly the vehicle user. The use of the structural adhesive according to the present invention to bond components provides significant benefits because the adhesive disperses the loads and stresses acting on the total bonding area rather than concentrating them at one point or a specific area of the bonding area, which allows for uniform dispersion of static and dynamic loads and thus reduces the vibration level of components within the secondary battery pack.

Further, it is known that the driving range of an electric vehicle between charges is calculated at ambient temperature. The electric vehicle driver may notice that the cold temperature decreases the available mileage. This loss is caused not only by the electrically heated car but also by the inherent slowing of the electrochemical reaction of the battery, which reduces the capacitance in cold. Thus, the selection of a particular material according to the invention makes it possible for said material to exhibit improved thermal insulation properties.

The temperature difference affects the resistance, self-discharge rate, coulombic efficiency, and irreversible capacity and power decay rate of the battery cells among a plurality of chemical reactions, and the secondary battery pack according to the present invention can provide uniform thermal conditions for all the cells of the battery pack or module. Thus further minimizing the cell state of charge imbalance and the likelihood of early failure of a defect-free cell.

According to a preferred embodiment, the organopolysiloxane polymer Y comprises at least one hydroxyl-terminated polyoxyalkylene moiety as a terminal group or as a pendant group, and wherein the polyoxyalkylene moiety has an average molecular weight of 300 to 4000g/mol, preferably 300 to 3500g/mol and even more preferably 300 to 3000g/mol.

According to another preferred embodiment, the organopolysiloxane polymer Y comprises hydroxyl-terminated polyoxyalkylene moieties as terminal groups or as pendant groups, and said organopolysiloxane polymer Y has the average general formula:

MD _x D* _y T* _z M

wherein the method comprises the steps of

M represents: (R) ₃ SiO _1/2 Or R is ¹ (R) ₂ SiO _1/2 ；

D represents (R) ₂ SiO _2/2 ；

D represents (R ¹ )(R)SiO _2/2 ；

T represents (R ¹ )SiO _3/2

X is in the range of from 5 to 220,

y is in the range of 2 to 50,

z is in the range of 0 to 50,

r is an alkyl group selected from methyl, ethyl, propyl, trifluoropropyl and phenyl, and most preferably R is methyl,

·R ¹ Is of the general formula-C _n H _2n O-(C ₂ H ₄ O) _a -(C ₃ H ₆ O) _b H, wherein n is 3 or 4, a>0 and b.gtoreq.0, and wherein a and b are defined such that the average molecular weight is 300 to 4000g/mol, preferably 300 to 3500g/mol and even more preferably 300 to 3000g/mol.

According to another preferred embodiment, the organopolysiloxane polymer Y comprises hydroxyl-terminated polyoxyalkylene moieties as terminal groups or as pendant groups and has the average general formula:

MD _x D* _y M

wherein the method comprises the steps of

M represents: (R) ₃ SiO _1/2 Or R is ¹ (R) ₂ SiO _1/2 ；

D represents (R) ₂ SiO _2/2 ；

D represents (R ¹ )(R)SiO _2/2 ；

X is in the range of from 5 to 220,

y is in the range of 2 to 50,

r is an alkyl group selected from methyl, ethyl, propyl, trifluoropropyl and phenyl, and most preferably R is methyl, and

According to another preferred embodiment, composition X is free of organopolysiloxane polymer Y comprising polyoxyalkylene branches having an average molecular weight of 4000g/mol or more; preferably, the organopolysiloxane polymer Y containing polyoxyalkylene branches having an average molecular weight of 3500g/mol or more; and even more preferably no organopolysiloxane polymer Y comprising polyoxyalkylene branches having an average molecular weight of 3000g/mol or more.

According to another preferred embodiment, composition X is free of organopolysiloxane polymer Y comprising polyoxyalkylene moieties having alkoxy end groups.

According to another preferred embodiment, R ¹ Is of the formula-C _n H _2n O-(C ₂ H ₄ O) _a -(C ₃ H ₆ O) _b Hydroxyl-terminated polyether branches of H, wherein n is 3 or 4, a is from 1 to 85, preferably from 5 to 60, and b is from 0 to 65, preferably from 4 to 60, and wherein a and b are defined such that the average molecular weight is from 300 to 4000g/mol, preferably from 300 to 3500g/mol and even more preferably from 300 to 3000g/mol.

According to another preferred embodiment, the molar ratio a/b is from 0.1 to 20, and preferably from 0.5 to 10, and even more preferably from 0.5 to 5.

Methods of preparing polydiorganosiloxane polyoxyalkylene copolymers according to the present invention are well known in the art. For example, polydiorganosiloxane polyoxyalkylene copolymers can be prepared by reacting a suitable alcohol with ethylene oxide and propylene oxide (1, 2-propylene oxide) to produce a polyoxyalkylene polyether having the desired molecular weight. Suitable alcohols are hydroxyalkenyl compounds such as vinyl alcohols or allyl alcohols. The above reaction yields a monohydroxy-terminated polyoxyalkylene polyether in which the other end-capping groups are unsaturated olefinic groups consisting of allyl, methallyl, or ethyleneoxy groups that can be further reacted with polydiorganosiloxanes containing silicon-bonded hydrogen atoms by hydrosilylation in the presence of a platinum group catalyst.

For example, hydroxyl terminated polyoxyalkylene polyethers, which are convenient starting materials for preparing terpolymers, can be prepared by reacting a suitable alcohol with ethylene oxide and propylene oxide (1, 2-propylene oxide) to produce polyoxyalkylene polyethers having the desired molecular weight. Suitable alcohols are hydroxyalkenyl compounds such as vinyl alcohol, allyl alcohol, methallyl alcohol, and the like.

The components of composition X are selected such that the viscosity of composition X prior to curing is sufficiently fluid to allow the composition to be applied as a liquid within a secondary battery pack to flow into the battery pack housing. In a preferred embodiment, the viscosity of the composition X at 25℃is from 100 to 10000 Pa.s, preferably from 100 to 6000 Pa.s.

The overall viscosity considered in the present specification corresponds to the dynamic viscosity magnitude, measured in a manner known per se at 25℃using a Brookfield type machine. With respect to fluid products, the viscosity considered in the present description is the dynamic viscosity at 25 ℃, called "newtonian" viscosity, i.e. the dynamic viscosity measured in a manner known per se at a sufficiently low shear rate gradient, such that the measured viscosity is independent of the rate gradient.

In a preferred embodiment, the isocyanate-based material a is a foam. An advantage of using the isocyanate-based material a in the form of a foam is to provide a lighter form of such material in response to the need to use lighter materials in vehicles using battery packs containing secondary cells to maximize their autonomous driving range before the cells need to be recharged.

Another advantage of using the isocyanate-based material a according to the invention in foamed form is that it has higher thermal insulation properties than non-foamed materials.

Depending on the foaming method, the foams obtained can be of different types: closed cell foam or open cell foam. Closed cell foams have the advantage of acting as a moisture vapor barrier and will not allow moisture to pass through the foam. The open cell foam will allow moisture to pass through. In a preferred embodiment, the isocyanate-based material a is a closed cell foam.

According to another preferred embodiment, the isocyanate-based material a is a foam prepared by a mechanical foaming process step, wherein a gas is added to the composition X by strong mechanical stirring before or during the curing step of the composition X.

In mechanical foaming (also known as mechanical foaming), an inert gas such as air, CO is stirred vigorously just before or during the polymerization/curing reaction ₂ Either nitrogen or a mixture of the foregoing gases is dispersed into the starting components, which leaves entrained bubbles within the polymer matrix. Mechanical foaming may include whipping, mixing, stirring, and the like. Readily available mixing devices can be used and typically no special devices are required. The amount of inert gas whipped into the liquid phase is controlled by a gas flow metering device to produce a foam having the desired density. The mechanical foaming may be performed in an Oakes mixer or a Hobart mixer.

According to another preferred embodiment, the isocyanate-based material a is a foam prepared by one of the following physical foaming methods:

using a low-boiling liquid as physical blowing agent and adding to composition X, when the temperature rise caused by the exothermic polymerization of composition X is higher than the boiling point of the low-boiling liquid, it evaporates to produce a foamed material, and finally the mixture can be heated to raise the temperature of the mixture, or

-using carbon dioxide (CO ₂ ) As physical blowing agent and into at least one component of composition X or into composition X at a high pressure above atmospheric pressure, followed by the CO being caused by a sudden pressure drop from the higher pressure to atmospheric pressure ₂ This causes cavities and creates foaming material.

When carbon dioxide is used as the physical blowing agent, it may be introduced as a liquid, supercritical fluid, or gas. Preferably at an elevated pressure of up to 100bar, preferably 10 to 100 bar. The foaming method comprises the following steps: dissolving carbon dioxide in composition X or one of its components, preferably under elevated pressure; nucleation of the bubble groups, preferably by releasing the pressure to ambient pressure; and finally the growth of nucleated bubbles entrained in the polymer matrix. For example, when component b) is an active hydrogen-containing compound such as a polyol, it is preferred to use, for example, a 100% to 200% volume level of CO ₂ Adding gas to the polyol orThe polyol is supplied to the composition X at a pressure of 10 to 20bar in the feed line, while the isocyanate is fed to the mixing chamber at high pressure (up to 100bar, preferably 10 to 100 bar) where the pressure drops to initiate foaming. In an embodiment, nitrogen as co-blowing agent is also added to the isocyanate component at high pressure (up to 100 bar).

When a low boiling point liquid such as a hydrocarbon (e.g., cyclopentane) or a hydrofluorocarbon is used as the physical blowing agent, a low molecular weight hydrocarbon such as propane, butane, pentane (such as n-pentane or cyclopentane) is preferred, dimethyl ether or fluorinated hydrocarbons such as 1, 3-pentafluoropropane (HFC-245 fa), 1, 3-pentafluorobutane (HFC-365 mfc), 1-fluorobutane, nonafluorocyclopentane, perfluoro-2-methylbutane, 1-fluorohexane, perfluoro-2, 3-dimethylbutane, perfluoro-1, 2-dimethylcyclobutane, perfluorohexane, perfluoroisohexane, perfluorocyclohexane, perfluoroheptane, perfluoroethylcyclohexane, perfluoro-1, 3-dimethylcyclohexane, perfluorooctane and 1, 2-tetrafluoroethane (HFC-134 a). They are vaporized by heat from the exothermic polymerization and foaming reactions.

Other suitable physical blowing agents include Hydrofluoroolefins (HFOs), such as trans-1, 3-tetrafluoroprop-1-ene (HFO-1234 ze, available under the trade name Honeywell ze), trans-1-chloro-3, 3-trifluoropropene (HFO-1233 zd, available from Arkema under the trade name Forane) ^TM Obtained) 2, 3-tetrafluoroprop-1-ene (HFO-1234 yf, available from Honeywell under the trade name solvent ^TM yf, and under the trade name Opteon from Chemours ^TM YF), cis-1, 4-hexafluoro-2-butene (HFO-1336 mzz-Z, available from Chemours under the trade name Opteon ^TM MZ obtained) and Opteon ^TM 1150 (available from Chemours).

In a specific embodiment, the isocyanate-based material a is a foam obtained by foaming a composition X prepared by mixing a first part a and a second part B, wherein:

the first part a comprises:

at least one organic compound having at least two epoxide groups or at least one active hydrogen-containing compound or a mixture of active hydrogen-containing compounds selected from the group consisting of polyols, polyamines, polyamides, polyimides and polyalcohols,

at least one organopolysiloxane polymer Y comprising at least one hydroxyl-terminated polyoxyalkylene moiety as a terminal group or as a pendant group,

at least one kind of drying agent is used,

at least one kind of catalyst, which is used in the reaction of the catalyst,

-optionally at least one blowing agent,

-optionally at least one adhesion promoter, and

-optionally at least one additive, which is selected from the group consisting of,

the second part B comprises:

at least one isocyanate compound, which is present in the mixture,

and wherein for 100 parts by weight of composition X it further comprises:

from 0.1 to 20 parts by weight, preferably from 1 to 15 parts by weight and most preferably from 2.5 to 10 parts by weight of at least one organopolysiloxane polymer Y comprising at least one hydroxyl-terminated polyoxyalkylene moiety as a terminal group or as a pendant group.

It has been found that by using a desiccant in part a above, the physical foaming process using carbon dioxide as Physical Blowing Agent (PBA) can be better controlled when foam is desired as material a by minimizing chemical foaming in part a due to the presence of water if it is present as blowing agent or water potentially present as moisture.

According to another preferred embodiment, the isocyanate-based material a is a foam prepared by a chemical foaming process step, wherein at least one foaming agent is present in the composition X, which foaming agent is foamed before or during the curing step of the composition X. In chemical foaming, the blowing agent is produced by a chemical reaction.

Examples of suitable chemical blowing agents include water and optionally one or more selected from the group consisting ofA compound: hydrocarbons, fluorocarbons and fluorohydrocarbons or at least one carboxylic acid selected from formic acid and acetic acid. Typically, the addition of water to the formulation will cause the water to react with the isocyanate to produce unstable carbamic acid which breaks down into amine and CO as a by-product ₂ This causes the polymer to foam. The amount of water present in the total mass of the composition (before reaction) is generally from 0.02 to 2.00% by weight, alternatively from 0.05 to 1.0% by weight, alternatively from 0.1 to 0.7% by weight (based on the total weight of composition X).

Other suitable chemical blowing agents include Si-OH compounds, which may be monomers, oligomers or polymers and in particular organosilanes and organosiloxanes having at least one silanol (Si-OH) group. Examples of suitable OH-functional compounds include dialkylsiloxanes such as OH-terminated dimethylsiloxane. The viscosity of such siloxanes may be 10 to 5000, 10 to 2500, 10 to 1000, 10 to 500, or 10 to 100mpa.s at 25 ℃.

In another embodiment, the chemical blowing agent may consist of a mixture of formic acid and water. The blowing agent may also consist of a mixture of at least 60% by weight of formic acid and at most 40% by weight of water. The amount of blowing agent used may vary depending on the desired properties. For example, the amount of blowing agent can be varied to adjust the final foam density and foam rise curve and cell size in the foamed article.

According to another preferred embodiment, both physical and chemical foaming methods (e.g. by adding water or silanol) are used in the combined chemical and physical foaming method.

According to a preferred embodiment, the isocyanate-based material a is a silicone polyurethane foam, a silicone-polyurea foam, a silicone-polyisocyanurate foam or a foam prepared from a mixture of silicone and polyurea, polyurethane and/or polyisocyanurate prepared by the above-described process.

As used herein, a foam is defined as a material having a number of cavities that may be filled with a gas such as air, oxygen, carbon dioxide, nitrogen, or any suitable gas. The cavities form a cell structure that extends throughout the bulk material. The foam may be closed cell, open cell or a mixture of both. Closed cell refers to a foam having cavities that form discrete cavities completely surrounded by solid material. Open cell refers to a foam having cavities connected to each other.

According to a preferred embodiment, an isocyanate-based material a is used as a gap filling material and as a structural adhesive, which completely or partially fills the open spaces of the battery pack housing 101 and/or the open spaces of the array of battery cells 103 and/or partially or completely covers the battery cells 103. The heat that diffuses from the cell to the adjacent cell can be effectively insulated by the isocyanate-based material a and thereby prevent thermal runaway from propagating through the entire battery and then threatening user safety. In addition, for some battery packs having a control circuit board disposed in the battery pack, the isocyanate-based material a of the present invention may be disposed between the battery cell array and the circuit board and between the battery cell array and the connection circuit to reduce battery heating problems caused by the circuit board and the connection circuit.

Examples of component (a) of composition X may be selected from the group consisting of monoisocyanates, diisocyanates, polyisocyanates, and mixtures thereof. By way of illustration, mention may be made of the components (a) used according to the invention and having at least one isocyanate function being monoisocyanates, diisocyanates or polyisocyanates and mixtures of these compounds, which are aromatic, cyclic, saturated or aliphatic and are known to the person skilled in the art. Suitable examples are Xylene Diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), hydrogenated Xylene Diisocyanate (HXDI), naphthalene 1, 5-diisocyanate (NDI), 4' -diphenylmethane diisocyanate (MDI), in particular 4,4' -diphenylmethane diisocyanate or 2,4' -diphenylmethane diisocyanate and Toluene Diisocyanate (TDI), in particular 2, 4-toluene diisocyanate and 2, 6-toluene diisocyanate. Other suitable examples are hexamethylene diisocyanate (HMDI), 1, 3-tetramethylxylylene diisocyanate, terephthalyl diisocyanate (PPDI), isophorone diisocyanate and 4,4' -dicyclohexyl hexamethylmethane diisocyanate (H) ₁₂ MDI). As examples of cycloaliphatic diisocyanates, mention may be made of Isophorone diisocyanate (IPDI).

As component (b) of composition X for producing polyurethane-based material a or polyisocyanurate-based material a, suitable, but not intended to be limited to, polyol compounds such as: polyfunctional polyethers (e.g., polyethylene glycol, polypropylene glycol, PTMG or polycaprolactone diol), polyester polyols (PEPO), acrylic polyols (ACPO), polycarbonate polyols, castor oil or mixtures thereof. Specific examples are: glycerol, polyglycerol, glycol, propylene glycol, glycols containing from 2 to 10 carbon atoms, preferably from 2 to 6 carbon atoms, such as ethylene glycol, diethylene glycol, 1, 4-butanediol, 1, 3-butanediol, 1, 2-propanediol, 2, 3-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 10-decanediol, 1, 3-propanediol, 2-methylpropane-1, 3-diol, 1, 4-cyclohexanediol, 1, 3-cyclohexanedimethanol, 1, 4-cyclohexanedimethanol, 2, 5-hexanediol, dipropylene glycol, polyethylene glycol, polypropylene glycol, neopentyl glycol, pentaerythritol, neopentyl glycol hydroxypivalate, dipentaerythritol, trimethylolpropane, 2-butyl-2-ethyl-1, 3-propanediol, sorbitol, mannitol, xylitol and meso-erythritol.

Esters of these diols or polyester polyols and polyether polyols may also be used. In a known manner, the polyester polyols are generally selected from aliphatic and aromatic polyester polyols and mixtures of these compounds. By way of example, mention may be made of polyester polyols formed by condensation of aliphatic, cyclic or aromatic polyols, such as 1, 2-ethylene glycol, 1, 2-propylene glycol, 1, 3-propylene glycol, glycerol, trimethylolpropane, 1, 6-hexanediol, 1,2, 6-hexanetriol, butanediol, sucrose, glucose, sorbitol, pentaerythritol and mannitol. The polyester polyols are generally obtained by using an excess of di-or polyfunctional alcohols in their transesterification with dicarboxylic acids or carboxylic anhydrides. Polyether polyols are generally obtained by anionic or cationic polyaddition of cyclic monomers such as ethylene oxide, propylene oxide or tetrahydrofuran. The polyether polyols used in the synthesis of polyurethanes generally have molar masses of from 250 to 8000. Their functionality may be from 2 to 7, depending on the nature of the molecule used as initiator. The end groups of these polyether diols may be primary or secondary groups.

As component (b) of composition X for producing polyurea-based material a, active hydrogen-containing compounds that can be used include compounds in which hydrogen bonds to nitrogen. Preferably, such compounds are selected from polyamines, polyamides, polyimines and polyalcohol amines, more preferably polyamines. Exemplary polyamines include ethylene diamine; neopentyl diamine; 1, 6-diaminohexane; bis-aminomethyl tricyclodecane; bis-aminocyclohexane; diethylenetriamine; bis-3-aminopropyl methyl amine; triethylene tetramine; various isomers of toluenediamine and diphenylmethane diamine; n-methyl-1, 2-ethylenediamine, N-methyl-1, 3-propylenediamine; n, N-dimethyl-1, 3-diaminopropane; n, N-dimethylethanolamine; 3,3' -diamino-N-methyldipropylamine; n, N-dimethyl-dipropylene triamine; aminopropylimidazole; and combinations thereof. Other specific examples of such compounds include primary and secondary amine terminated polyethers. Preferably, such polyethers have a molecular weight greater than about 230 and a functionality of from 1 to 3. Such amine-terminated polyethers are well known and are prepared by adding a lower alkylene oxide to a suitable starter and then aminating the resulting hydroxyl-terminated polyol.

As component (b) of the organic compound having at least two epoxy groups of composition X, any aliphatic, cycloaliphatic, aromatic and/or heterocyclic compound having at least two epoxy groups may be mentioned. In particular, any aromatic compound having at least two epoxy groups may be suitable. Other suitable polyepoxides include, for example, polyglycidyl ethers of the following polyhydric phenols: such as catechol, resorcinol, hydroquinone, 4' -dihydroxydiphenylpropane (bisphenol A), 4' -dihydroxy-3, 3' -dimethyldiphenylmethane, 4' -dihydroxydiphenylmethane (bisphenol F), 4,4' -dihydroxydiphenyl cyclohexane, 4' -dihydroxy-3, 3' -dimethyldiphenylpropane, 4' -dihydroxybiphenyl, 4' -dihydroxydiphenyl sulfone (bisphenol S) and tris (4-hydroxyphenyl) methane. Mention may furthermore be made of: polyepoxides based on aromatic amines and epichlorohydrin, such as N-bis (2, 3-epoxypropyl) aniline, N, N ' -dimethyl-N, N ' -diglycidyl-4, 4' -diaminodiphenylmethane or N, N-diglycidyl-4-aminophenyl glycidyl ether. Additionally, it is possible to use: glycidyl esters of polyvalent aromatic, aliphatic and cycloaliphatic carboxylic acids, for example diglycidyl phthalate, diglycidyl isophthalate, diglycidyl terephthalate, diglycidyl adipate, and glycidyl esters of the reaction products of 1 mole of an aromatic or cycloaliphatic dicarboxylic anhydride with 1/2 mole of a diol or 1/n mole of a polyol having n hydroxyl groups, or diglycidyl hexahydrophthalate, which may optionally be substituted with methyl groups. Other suitable examples include, for example, glycidyl ethers of the following polyvalent alcohols: 1, 4-butanediol, 1, 4-butenediol, glycerol, trimethylolpropane, pentaerythritol and polyethylene glycol. Epoxidation products of polyunsaturated compounds such as vegetable oils and their conversion products may also be used.

As component (c) of composition X, suitable catalysts are selected from organotin compounds. As component (c), suitable catalysts are compounds capable of catalyzing the polymerization reaction. Such catalysts are known and their choice and concentration are within the knowledge of those skilled in the art. See, for example, U.S. patent nos. 4,296,213 and 4,518,778. Non-limiting examples of suitable catalysts include tertiary amines and/or organometallic compounds.

Furthermore, when the goal is to produce isocyanurate material, it is preferred that the lewis acid be used as a catalyst alone or in combination with other catalysts, as is known in the art. Examples are tin (ll) salts of organic carboxylic acids, such as dibutyltin dilaurate (e.g. under the trademark DABCO ^TM Commercially available from Air Products and Chemicals, inc.), dioctyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate and dibutyltin bis (dodecyl mercaptan). Tin-free catalysts such as organotitanates, iron catalysts such as organoiron compounds, organic and inorganic heavy metal compounds or tertiary amines may also be used. An example of an organic iron compound is iron (III) acetylacetonate. Examples of tertiary amines are triethylamine, tri-N-butylamine, tetramethylethylenediamine, tetramethylhexamethylenediamine, pentamethyldiethylenetriamine, pentamethyldipropylenetriamine, dimethylpiperazine, 1, 2-dimethylimidazole, N-ethylmorpholine, tris (dimethylaminopropyl) hexahydro-1, 3, 5-triazine, dimethylaminoethanol 1, 4-diazabicyclo [ 2.2.2.2]Octane, N, N-bis (N, N-dimethyl-2-aminoethyl) methylamine, N, N-dimethylcyclohexylamine ("DMCHA"), N, N-dimethylphenylamine, bis (N, N-dimethylaminoethyl) ether, N, N-dimethyl-2-aminoethanol, N, N-dimethylaminopyridine, N, N, N, N-tetramethyl (bis (2-aminoethyl) methylamine, 1, 5-diazabicyclo- [4.3.0]Non-5-ene, 1, 8-diazabicyclo [5.4.0]Undec-7-ene ("DBU") and N-ethylmorpholine. Other suitable examples are dimethylbenzylamine, methyldibenzylamine, boron trichloride tertiary amine adducts and N- [3- (dimethylamino) propyl ]]Formamide. The catalyst may be used in pure form or in a support medium (which may be referred to as a solvent). The carrier medium may be isocyanate reactive, for example an alcohol functional carrier medium such as dipropylene glycol, silicones (both linear and cyclic), organic oils, organic solvents and mixtures thereof.

The relative proportions of isocyanate groups to isocyanate-reactive groups may be varied as desired, preferably the molar ratio [ NCO ]/[ isocyanate-reactive groups ] is from 0.9:1 to 2:1. Preferably, the molar ratio is from 1:1 to 1.8:1, alternatively from 1.1:1 to 1.6:1, alternatively from 1.1:1 to 1.4:1.

Polyurethane materials are typically obtained by reacting an organic isocyanate compound with a polyol in the presence of a tin or tertiary amine catalyst to an NCO/OH equivalent ratio of about 0.9 to 1.2, while polyisocyanurate materials are preferably obtained by reacting them in the presence of a trimerization catalyst to an NCO/OH equivalent ratio of about 3.0 or greater. Examples of suitable trimerisation catalysts are carboxylates such as potassium 2-ethylhexanoate.

When present, the blowing agent component (d) may be selected from water, hydrohaloolefins such as trans-1-chloro-3, 3-trifluoroprop-1-ene, trans-1, 3-tetrafluoropropene, 1, 4-hexafluorobutene or mixtures thereof. The blowing agent is generally used in an amount of up to 50% by weight of the active hydrogen-containing compound.

When present, the adhesion promoter (e) may be selected from amino-containing adhesion promoters selected from aminoalkyl trialkoxysilanes, aminoalkyl dialkoxysilanes, bis (alkyl trialkoxysilyl) amines, tris (alkyl trialkoxysilyl) amines, or combinations of two or more thereof. Examples are N- (2-aminoethyl) aminopropyl trimethoxysilane, γ -aminopropyl triethoxysilane, γ -aminopropyl trimethoxysilane, bis (γ -trimethoxysilylpropyl) amine, N-phenyl- γ -aminopropyl trimethoxysilane, tri-amino functional trimethoxysilane, γ -aminopropyl methyldimethoxysilane, γ -aminopropyl methyldiethoxysilane, ω -bis- (aminoalkyl-diethoxysilyl) -polydimethylsiloxane (pn=1-7), α, ω -bis- (aminoalkyl-diethoxysilyl) -octamethyltetrasiloxane, 4-amino-3, 3-dimethyl-butyl-trimethoxysilane, and N-ethyl-3-trimethoxysilyl-2-methylpropylamine, 3- (diethyl-aminopropyl) -trimethoxysilane, and combinations of two or more thereof, and the like. Particularly suitable amino-containing adhesion promoters include bis (alkyl trialkoxysilyl) amines and tris (alkyl trialkoxysilyl) amines, including but not limited to bis (3-propyl trimethoxysilyl) amine and tris (3-propyl trimethoxysilyl) amine. Other suitable adhesion promoters include vinyltrimethoxysilane, (3-glycidoxypropyl) trimethoxysilane, and the like.

When present, additive component (f) may be selected from flame retardant additives, smoke suppressants, antibacterial compounds, stabilizers, plasticizers, surfactants, fillers, dyes, pigments, crosslinking additives, fragrances, cleaning agents, fillers and antistatic agents. These optional components are well known in the art and the amounts of these optional components are conventional and not critical to the invention.

Examples of surfactants include fluorocarbon surfactants, organofluorinated surfactants or fluorinated surfactants containing silicon.

Examples of pigments include carbon black, such as acetylene black.

Examples of suitable fillers include reinforcing fillers, non-reinforcing fillers, filler fillers, or mixtures thereof. Examples of reinforcing fillers include high surface area fumed silica and precipitated silica and calcium carbonate. Examples of non-reinforcing fillers include crushed quartz, diatomaceous earth, barium sulfate, iron oxide, titanium dioxide and carbon black, carbon nanotubes, talc, hollow glass beads, and wollastonite.

Examples of hollow glass beads and in particular hollow glass microspheres include those selected from 3M ^TM Glass bulb floatation series (A16/500, G18, A20/1000, H20/1000, D32/4500 and H50/10000EPX glass bulb 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) are sold by 3M company.

In a preferred embodiment, the additive component (f), when present, is present in an amount of from 0.1 to 30 parts by weight, preferably from 0.5 to 15 parts by weight and most preferably from 0.5 to 10 parts by weight, relative to 100 parts by weight of the composition X.

According to a preferred embodiment, the secondary battery pack further comprises:

at least one thermal insulation material B which partially fills the open space of the battery housing 101 and/or partially fills the open space within the array of battery cells 103 and/or partially covers the battery cells 103, and preferably the thermal insulation material B is in the form of a foam, fabric, floe or intumescent material, and even more preferably the thermal insulation material B is a composite foam, a polymer foam or a non-polymer foam selected from aerogel and porous ceramic, and

use of isocyanate-based material a as binder and filling the remaining open space left by thermally insulating material B.

In this embodiment, the isocyanate-based material a surrounds the array of cells 103 with the thermally insulating material B completely or partially filling it.

As a preferred embodiment, the thermal insulation material B is a silicone foam or a silicone composite foam.

According to another embodiment:

using an isocyanate-based material a as a binder, which partially fills the open space of the battery pack case 101 and/or partially fills the open space of the array of battery cells 103 and/or partially covers the battery cells 103, and finally is present under the battery cells 103, and

the secondary battery further comprises at least one thermal insulation material B applied as a top layer and/or as a bottom layer onto said isocyanate-based material a, and preferably the thermal insulation material B is in the form of a foam, a fabric, a floe or an expanded material, and even more preferably the thermal insulation material B is a composite foam, a polymer foam or a non-polymer foam selected from aerogels and porous ceramics.

An advantage of this embodiment is that the cell array of the secondary battery is secured with isocyanate-based material a, while thermally insulating material B protects the electrical connection, prevents arcing and reduces the risk of thermal runaway when the cell is vented up through the weakest part of the cell structure. In this embodiment, the thermal insulation material B is preferably selected from a silicone foam or a silicone composite foam.

In a preferred embodiment, the thermal insulation material B is a polymer foam or a syntactic foam prepared from a polymer selected from the group consisting of silicones, epoxies, polyurethanes, polyimides, aromatic polyethers and sulfones. Silicone syntactic foam is the most preferred thermal insulation material B.

To further improve the adhesive properties, the composition X preferably contains at least one adhesion promoter (e) as defined above.

Examples of suitable polymer foams for thermal insulation material B include the foamed compositions as described above and comprise the main components as described above:

(a) At least one kind of the isocyanate compound(s),

(b) At least one organic compound having at least two epoxide groups or at least one active hydrogen-containing compound or a mixture of active hydrogen-containing compounds selected from the group consisting of polyols, polyamines, polyamides, polyimines and polyalcohol amines.

(c) At least one of the catalysts is selected from the group consisting of,

(d) Optionally at least one of the blowing agents,

(e) Optionally at least one adhesion promoter, and

optionally at least one additive.

When the isocyanate-based material a is used with the thermal insulation material B, different embodiments are possible.

According to a preferred embodiment, the battery cell 103 is of the lithium ion type.

According to another preferred embodiment, the secondary battery pack according to the present invention further comprises a plurality of heat dissipation members disposed at two or more interfaces between the battery cells or under the array of the battery cells 103, and at least one heat exchange member integrally interconnected with the heat dissipation members, whereby heat generated from the battery cells during charge and discharge of the battery cells is removed through the heat exchange member. This makes the cooling efficiency of the battery cells higher than that of the conventional cooling system even when there is no space between the battery cells or very little space between the battery cells, thereby maximizing the heat dissipation efficiency of the secondary battery pack.

According to another preferred embodiment, the heat-dissipating element according to the invention is made of a heat-conducting material exhibiting a high thermal conductivity, and the heat-exchanging element is provided with one or more coolant channels for allowing a coolant, such as a liquid or a gas, to flow therein.

The heat dissipation elements according to the present invention are not particularly limited as long as each heat dissipation element is made of a heat conduction material exhibiting high heat conductivity, such as a metal plate.

Preferably, the heat exchange element is provided with one or more coolant channels for flowing a coolant therethrough. For example, coolant channels for flowing a liquid coolant such as water therein may be formed in the heat exchange element, thereby providing excellent cooling effect and high reliability as compared to conventional air cooling structures.

According to another preferred embodiment, the secondary battery pack according to the present invention further comprises a coolant inlet header, a coolant outlet header, and a plurality of heat exchange tubes as heat radiating members and extending between the inlet header and the outlet header, the heat exchange tubes being arranged at one or more interfaces between the battery cells and/or under the array of battery cells 103, and passing a coolant to exchange heat generated by the battery cells during charge and discharge of the battery cells.

According to another preferred embodiment, the cells 103 are cylindrical batteries and are arranged in a plurality of cell rows to produce an array of cells 103, and preferably the array is designed to produce a honeycomb-like array of cells.

In a preferred embodiment, the secondary battery pack also contains a honeycomb structure in which the battery cells 103 are embedded and held to form an array of battery cells 103.

The battery enclosure 101 is comprised of an enclosure top plate 104 and an enclosure bottom plate 102, which when sealed to each other provide a substantially airtight battery enclosure 101. Which is configured to house a plurality of battery cells. The secondary battery pack may further include a ballistic shield mounted under the electric vehicle and interposed between the battery pack case and the cabin surface. The ballistic shield may be manufactured from aluminum, aluminum alloys, steel, fiberglass, carbon fiber/epoxy composites, and/or plastics.

The battery pack housing 101 may be substantially airtight and may be made of aluminum, aluminum alloy, or steel.

According to a preferred embodiment, the secondary battery pack according to the present invention is located in a vehicle.

It is to be understood that the term "vehicle" as used herein generally includes motor vehicles such as passenger vehicles (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 vehicles, hydrogen energy vehicles, and other alternative fuel vehicles (e.g., fuel derived from sources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle having two or more power sources (e.g., both gasoline and electric).

In another preferred embodiment, the secondary battery pack according to the present invention is located in a motor vehicle.

In another embodiment, the secondary battery pack according to the present invention is located in a pure Electric Vehicle (EV), a plug-in hybrid vehicle (PHEV), a hybrid vehicle (HEV).

In another embodiment, the secondary battery pack according to the present invention is located in an aircraft, a boat, a ship, a train, or a wall device.

Another object of the present invention relates to a method for preparing a secondary battery pack according to the present invention and as defined above, comprising the steps of:

a) A battery enclosure 101 is provided, which is comprised of an enclosure top plate 104 and an enclosure bottom plate 102, which when sealed provide a substantially airtight enclosed environment within the battery enclosure 101,

b) At least one array of battery cells 103, which are electrically connected to each other and arranged in an upright manner such that the battery axes are parallel to each other,

c) The composition X according to the present invention and as defined above is introduced into the open space of the battery pack housing 101 and/or the open space of the array of battery cells 103,

d) The open space of the battery pack case 101 and/or the open space of the array of battery cells 103 is fully or partially filled and/or the battery cells 103 are partially or fully covered with the composition X,

e) Curing to form material A, and

f) The housing top plate 104 and the housing bottom plate 102 are sealed to provide the battery housing 101.

In a preferred embodiment, the method according to the invention comprises the steps of:

c) The composition X according to the invention and defined above is introduced into the housing floor 102 and/or into the open space of the array of battery cells 103,

e) Before, during or after filling step d), the composition X as defined according to the invention and in the description is brought to start curing and foaming to form an isocyanate-based material A which is a foam, and

f) The housing top plate 102 and the housing bottom plate 104 are sealed to each other to provide a substantially airtight battery housing 101.

In another preferred embodiment, the method according to the invention comprises the following steps:

c) At least one thermal insulation material B or a curable precursor thereof is introduced into the open space of the battery pack housing 101, which after curing partially fills the open space of the battery pack housing 101 and/or partially fills the open space of the array of battery cells 103 and/or partially covers the battery cells 103,

d) The composition X defined above is introduced into the open space of the battery pack case 101 and/or into the open space of the array of battery cells 103,

e) The remaining open space of the battery pack case 101 left by the thermal insulation material B and/or the remaining open space of the array of battery cells 103 and/or the remaining open space covering the battery cells 103 is filled with the composition X,

f) Curing to form material A, and

g) The housing top plate 104 and the housing bottom plate 102 are sealed to provide the battery housing 101.

In another embodiment, the thermal insulation material B is in the form of a foam, fabric, floe, or intumescent material, and even more preferably the thermal insulation material B is a composite foam, a polymeric foam, or a non-polymeric foam selected from aerogels and porous ceramics.

By "syntactic foam" is meant a composite comprising preformed hollow spheres (typically made of glass, ceramic, polymer or metal) dispersed in a polymeric binder. Specific examples of polymeric binders are those obtained from chemical precursors bearing reactive groups, which under the action of a catalyst produce a polymeric cured material, and which may be selected from the following classes of precursors, including: silicones, epoxies, polyurethanes, polyimides, aromatic polyethers and sulfones.

In a preferred embodiment, the thermal insulation material B is a silicone syntactic foam. Examples of suitable silicone syntactic foams are described in U.S. patent application number US-se:Sup>A-2018223070 filed by Elkem Silicones USA Corp.

In a preferred embodiment, hollow glass beads are used in a composite foam and function to reduce the density of the foam. Hollow glass beads and especially hollow glass microspheres are very well suited for the present application because, in addition to having excellent isotropic compressive strength, they have the lowest density of any filler that can be used to make a high compressive strength composite foam. The combination of high compressive strength and low density makes hollow glass microspheres a filler material according to the present invention having numerous advantages.

According to one embodiment, the hollow glass beads are hollow borosilicate glass microspheres, also referred to as glass bubbles or glass microbubbles.

According to another embodiment, the hollow borosilicate glass microspheres have a true density of 0.10g/cm ³ (g/cc) to 0.65g/cm ³ (g/cc)。

The term "true density" is the quotient of the mass of the glass bubble sample divided by the true volume of the glass bubble material, as measured by a gas densitometer. The "true volume" is the aggregate total volume of the glass bubbles, not the bulk volume.

According to a preferred embodiment, the hollow glass beads are selected from 3M ^TM Glass bulb floatation series (A16/500, G18, A20/1000, H20/1000, D32/4500 and H50/10000EPX glass bulb 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) are sold by 3M company. The glass bubbles exhibited different crush strengths of 1.72 megapascals (250 psi) to 186.15 megapascals (27000 psi), where 10% by volume of the first glass bubbles collapsed. According to the invention, other glass bubbles sold by 3M such as 3M ^TM Glass bubbles float series, 3M ^TM Glass bubble-HGS series and surface treated 3M ^TM Glass bubbles may also be used.

According to a preferred embodiment, the glass bubbles are selected from those exhibiting a crush strength of 1.72 megapascals (250 psi) to 186.15 megapascals (27000 psi), where within this strength range, 10% by volume of the first batch of glass bubbles collapse.

According to a most preferred embodiment, the hollow glass beads are selected from 3M ^TM Glass bubbles series, S15, K1, K25, iM16K, S32 and XLD3000.

In another preferred embodiment, thermal insulation material B is a composite foam or a polymer foam that can be introduced into the battery pack housing as a liquid precursor, cured in situ to produce thermal insulation material B.

The thermal insulation material B may be in the form of foam, fabric, floe, intumescent material. Specific examples include polymeric foams such as silicone, epoxy, polyurethane, polyimide, aromatic polyether and sulfone, and phenolic foams.

Drawings

Fig. 1 provides a top view of a secondary battery pack without a top case plate 104, with an array of battery cells 103 within a bottom case plate 102 (electrical connections for the battery cells are not shown).

Fig. 2 provides a perspective view of a secondary battery pack in which an array of battery cells 103 are disposed within a housing floor 102 (electrical connections for the battery cells are not shown).

Fig. 3 provides a top view of the cells in a secondary battery in which an isocyanate-based material a (labeled as component a in the figure) according to the present invention fills the spaces between the array of cells 103 and the remaining space of the housing floor 102 (the electrical connections of the cells are not shown).

Fig. 4 provides a top view of an array of battery cells 103 in a secondary battery covered with an isocyanate-based material a (labeled as component B in the figure) according to the present invention, and wherein the isocyanate-based material a fills the spaces between the cells and the remaining spaces of the battery (the electrical connections of the battery cells are not shown).

Fig. 5 provides a top view of an array of cells 103 designed to create a honeycomb-like array of cells 103 (electrical connections for the cells are not shown).

Fig. 1 and 2 illustrate that the battery cells 103 may be very closely together within the housing floor 102. In one embodiment of the present invention, after the array of battery cells has been placed and installed, a precursor of composition X and material a according to the present invention is poured into the backplane housing 102 (fig. 3, 104) and upon curing thereof an isocyanate-based material a according to the present invention is produced (fig. 4, 105). If a foaming process is used (mechanical, physical or chemical foaming as described above), material A is obtained as a foam after curing. Fig. 5 provides a top view of an array of cells 103, which is a cylindrical battery, and arranged in a plurality of cell rows to produce an array of cells 103, and the array is designed to produce a honeycomb-like array of cells 103.

Other advantages offered by the present invention will become more apparent from the following illustrative examples.

Examples

I) Test program

Lap shear procedure

Stainless steel lap shears were obtained from Q labs (SS-13:76.2 inch x 25.4 inch x 0.889 mm) and wiped with isopropyl alcohol to clean the surfaces to be bonded prior to use. Lap shear substrates were prepared by applying adhesive to the bonding area on one lap shear, aligning a second lap shear on top of it, creating a 12.7mm overlap of lap shears (bonding area), and then clamping the lap shears together using one inch spring clamps on both sides of the bonding/overlap area. The finished substrates were then cured at room temperature for a minimum of 4 days, and then tested for their tensile strength at a rate of 2 inches/minute according to ASTM D1005 (Elkem TL-0288) on an Instron Model 4301. Five samples were tested under each condition. The maximum and minimum values are truncated.

Tensile Strength and elongation

The slabs were cast in 152×152×2mm molds. The finished slab was cured at room temperature for a minimum of 4 days. The samples were then die cut using die cut to produce class I dimensions according to ASTM D638-14 "standard test method for tensile properties of plastics". The three samples were tested for maximum stress (labeled "T & E maximum stress" in Table 2) and elongation (strain% labeled "T & E strain (%)" in Table 2) using an Instron Model 4301 with a telescoping instrument at a test speed of 5.08 mm/min.

Flexural modulus

The test specimens were cast in 147X 25X 3mm molds. The finished slab was cured at room temperature for a minimum of 4 days. Three samples under each condition were tested on a Texture Analyzer using a 50kg load cell using a 50mm three-point curved spacer. Flexural modulus is calculated using ASTM D790-17 "standard test method for flexural properties of unreinforced and reinforced plastics and electrical insulation materials".

Shore D hardness tester

Samples were cast in 147 x 25 x 3mm molds. The completed slab was cured at room temperature for a minimum of 4 days. The samples were tested according to ASTM D2240-15 "Standard test method for rubber Properties-durometer hardness". Three samples were tested for each formulation.

Definition of II) Components

Stobicast M598 is a two-component polyurethane potting compound.

Unipoly 66A (provided by Unipoly Performance Material Co), part a=as a polymer matrix, comprising polyether polyol, glycol chain extender, alumina trihydrate, dibutyltin dilaurate, viscosity: <2000mpa.s (measured at 25 ℃).

Unipoly 66B (provided by Unipoly Performance Material Co), part b=polyurethane foam precursor (blend of diisocyanate, catalyst, flame retardant package and additives).

Additive 1: garamite-1958, an organophilic phyllosilicate (rheological additive) in powder form, from BYK.

Additive 2: stan-tone 40ET01 blue pigment.

Additive 3: moliv 3A-zeolite molecular sieve desiccants and adsorbents.

The tin masterbatch had the following formulation (wt.%):

98.5% Unipoly 66A

0.5% of dibutyl tin dilaurate

1.0% of additive 1

Glymo: glycidyl 3- (trimethoxysilyl) propyl ether.

Silicone polyether 1 (control, polyether terminated with acetate groups): sildurf J1015-O-AC from Siltech: INCI is named PEG/PPG 18/18 simethicone, and acetate endcapped, mw=27000 g/mol (the polyether backbone has the structure: r= -C ₃ H ₆ O-(C ₂ H ₄ O) ₁₈ -(C ₃ H ₆ O) ₁₈ (COCH ₃ ))。

Silicone polyether 2 (polyether terminated with-OH groups according to the invention): total OH content (about 0.595 wt% OH) having the formula: m D ₆₀ D* ₆ M, wherein:

οM＝(CH ₃ ) ₃ SiO _1/2

οD＝(CH ₃ ) ₂ SiO _2/2

οD*＝(CH ₃ )(R)SiO _2/2 wherein r= -C ₃ H ₆ O-(C ₂ H ₄ O) ₂₂ -(C ₃ H ₆ O) ₂₂ H

III) formulations and materials tested

Samples were formulated from part a, part B and catalyst (0.5% tin masterbatch). The composition of each part a is given in table 1. Part a was mixed in a fluktek 300 maximum cup of a high speed mixer. Unipoly 66A and Garamite-1958 (additive 1) were first mixed at 2000rpm for 3min. The pigment GLYMO silane and polyether were then added and mixed at 2000rpm for 3min. Part a was placed under nitrogen and stored. Samples were prepared by manually mixing part a, tin catalyst and part B for about 1 min. Samples were cast in 2mm molds coated with a release spray for tensile and elongation testing. The second formulation was mixed and samples therefrom were cast in a 3mm mold to prepare lap shear samples.

Each test was repeated 3 times and the properties of the resulting materials are shown in table 2.

Table 1: sample formulation (all% by weight)

Table 2: properties of the cured Material

Samples were formulated from part a, part B described above with the formulations described in test 9 to test 16 (see tables 3 and 4). To obtain a foamed (foamed) sample via mechanical foaming: mechanical foaming was performed using a Hamilton beacon 2 high speed hand blender with a stirring accessory. After part a was added to the vessel, the material was whipped using a blender at low speed for 30-60 seconds. Then add part B. The materials were hand mixed for about 30 seconds. And then whipped using a blender at low speed for 30 to 60 seconds. The material is then allowed to set at ambient temperature and the curing is completed.

Table 3: sample formulation (all% by weight)

Table 4: sample formulation (all% by weight)

The properties of tests 9 to 16 are shown in tables 5 and 6 below.

CF = cohesive failure mode

AF = adhesion failure mode

Table 5: properties of (C)

Table 6: properties of (C)

For the foamed form (foamed form), the tensile strength of the formulation according to the invention is improved, which allows the use of foamed products with a density below 1.0 in the battery.

Comparison of tests 15 (foaming, invention) and 16 (foaming, control) showed an improvement of + 60.67%.

Comparison of tests 13 (foaming, invention) and 14 (foaming, control) showed an improvement of + 19.50%.

Comparison of tests 11 (foaming, invention) and 12 (foaming, control) showed an improvement of + 23.49%.

The advantage of the material according to the invention is that it has good structural bonding properties and improved tensile strength properties as well as good lap shear strength, which is the ability of the material to resist forces in the plane of the adhesive surface, which improves the impact resistance of the structure to protect the battery cell and more importantly the vehicle user.

Claims

1. A secondary battery pack 100, comprising:

at least one array of battery cells 103 within the housing floor 102, which are electrically connected to each other and arranged in an upright manner such that the axes of the batteries are parallel to each other,

(a) At least one kind of the isocyanate compound(s),

(c) At least one of the catalysts is selected from the group consisting of,

(d) Optionally at least one of the blowing agents,

(e) Optionally at least one adhesion promoter, and

(f) Optionally at least one of the additives is used,

and wherein for 100 parts by weight of composition X it further comprises:

from 0.1 to 30 parts by weight, preferably from 0.1 to 20 parts by weight and even more preferably from 4.5 to 30 parts by weight of at least one organopolysiloxane polymer Y comprising at least one hydroxyl-terminated polyoxyalkylene moiety as a terminal group or as a pendant group.

2. The secondary battery according to claim 1, wherein the organopolysiloxane polymer Y comprises at least one hydroxyl-terminated polyoxyalkylene moiety as a terminal group or as a pendant group, and wherein the polyoxyalkylene moiety has an average molecular weight of 300 to 4000g/mol, preferably 300 to 3500g/mol and even more preferably 300 to 3000g/mol.

3. The secondary battery of claim 1, wherein the organopolysiloxane polymer Y comprises hydroxyl-terminated polyoxyalkylene moieties as end groups or as side groups, and the organopolysiloxane polymer Y has the average general formula:

MD _x D* _y T* _z M

wherein the method comprises the steps of

● M represents: (R) ₃ SiO _1/2 Or R is ¹ (R) ₂ SiO _1/2 ；

● D represents (R) ₂ SiO _2/2 ；

● D represents (R ¹ )(R)SiO _2/2 ；

● T represents (R ¹ )SiO _3/2

● x is a number from 5 to 220 and,

● y is a number from 2 to 50,

● z is in the range of 0 to 50,

● R is an alkyl group selected from methyl, ethyl, propyl, trifluoropropyl and phenyl, and most preferably R is methyl,

●R ¹ is a hydroxyl terminated polyether moiety having the general formula:

■-C _n H _2n O-(C ₂ H ₄ O) _a -(C ₃ H ₆ O) _b h, wherein n is 3 or 4, a>0 and b.gtoreq.0, and wherein a and b are defined such that the average molecular weight is 300 to 4000g/mol, preferably 300 to 3500g/mol and even more preferably 300 to 3000g/mol.

4. The secondary battery pack according to claim 1, wherein:

the secondary battery further comprises at least one thermal insulation material B which partially fills the open space of the battery housing 101 and/or partially fills the open space within the array of battery cells 103 and/or partially covers the battery cells 103, and preferably the thermal insulation material B is in the form of a foam, fabric, floe or expanded material, and even more preferably the thermal insulation material B is a composite foam, a polymer foam or a non-polymer foam selected from aerogels and porous ceramics, and

-filling the remaining open spaces left by the thermal insulation material B using the isocyanate-based material a as an adhesive.

5. The secondary battery pack according to claim 1, wherein:

-using the isocyanate-based material a as an adhesive, which partially fills the open space of the battery housing 101 and/or partially fills the open space within the array of battery cells 103 and/or partially covers the battery cells 103, and is finally present under the battery cells 103, and

the secondary battery further comprises at least one thermal insulation material B applied as a top layer and/or as a bottom layer onto the isocyanate-based material a, and preferably the thermal insulation material B is in the form of a foam, a fabric, a floe or an expanded material, and even more preferably the thermal insulation material B is a composite foam, a polymer foam or a non-polymer foam selected from aerogels and porous ceramics.

6. The secondary battery pack according to claim 1, wherein the isocyanate-based material a is a foam.

7. The secondary battery pack according to claim 6, wherein the isocyanate-based material a is a foam prepared by a mechanical foaming method step, wherein a gas is added to the composition X by mechanical stirring before or during the curing step of the composition X.

8. The secondary battery pack according to claim 6, wherein the isocyanate-based material a is a foam prepared by one of the following physical foaming methods:

-using a low boiling point liquid as physical blowing agent and adding it to composition X, which evaporates to produce a foamed material when the temperature rise caused by the exothermic polymerization of composition X is above the boiling point of said low boiling point liquid, or

-using carbon dioxide (CO ₂ ) As physical blowing agent and into at least one component of composition X or into composition X at a high pressure above atmospheric pressure, followed by the CO being caused by a sudden pressure drop from the higher pressure to atmospheric pressure ₂ Which causes cavities and creates a foaming material.

9. The secondary battery pack according to claim 6, wherein the isocyanate-based material a is a foam obtained by foaming a composition X prepared by mixing a first part a and a second part B, wherein:

● The first portion a comprises:

at least one organic compound having at least two epoxide groups or at least one active hydrogen-containing compound or a mixture of active hydrogen-containing compounds selected from the group consisting of polyols, polyamines, polyamides, polyimines and polyalcohol amines,

at least one kind of drying agent is used,

at least one kind of catalyst, which is used in the reaction of the catalyst,

-optionally at least one blowing agent,

-optionally at least one adhesion promoter, and

● The second portion B comprises:

at least one isocyanate compound, which is present in the mixture,

and wherein for 100 parts by weight of composition X it further comprises:

10. The secondary battery of claim 6, wherein the isocyanate-based material a is a foam prepared by a chemical foaming process step, wherein at least one blowing agent is present within composition X, the blowing agent foaming prior to or during the curing step of composition X.

11. The secondary battery pack according to claim 6, wherein the isocyanate-based material a is a foam prepared by a physical foaming method and a chemical foaming method.

12. The secondary battery pack according to claim 4 or 5, wherein the thermal insulating material B is a silicone composite foam.

13. The secondary battery pack according to claim 1, wherein the battery cells 103 are cylindrical batteries, and are arranged in a plurality of battery cell rows to produce an array of battery cells 103.

14. The secondary battery pack according to claim 1, wherein the secondary battery pack further contains a honeycomb structure in which the battery cells 103 are embedded and held, forming an array of battery cells 103.

15. The secondary battery pack according to any one of claim 1, wherein the battery cell 103 is of a lithium ion type.

16. The secondary battery pack according to any one of claims 1 to 15, which is located in a vehicle.

17. The secondary battery pack according to any one of claims 1 to 15, which is located in an automotive vehicle.

18. The secondary battery pack according to any one of claims 1 to 15, which is located within a pure Electric Vehicle (EV), a plug-in hybrid vehicle (PHEV), a hybrid vehicle (HEV).

19. The secondary battery pack according to any one of claims 1 to 15, which is located within an aircraft, a boat, a ship, a train, or a wall device.

20. A method of preparing a secondary battery pack as defined in any one of claims 1 to 15, comprising the steps of:

b) At least one array of battery cells 103, which are electrically connected to each other and arranged in an upright manner, such that the axes of the batteries are parallel to each other,

c) Introducing the composition X as defined in any one of claims 1 to 3 into the open space of the battery pack housing 101 and/or the open space of the array of battery cells 103,

d) Curing to form material A, and

e) The housing top plate 104 and the housing bottom plate 102 are sealed to provide the battery housing 101.

21. A method of preparing a secondary battery pack as defined in any one of claims 1 to 19, comprising the steps of:

c) Introducing the composition X as defined in any one of claims 1 to 3 into the housing floor 102 and/or into the open space of the array of battery cells 103,

e) Initiating curing and foaming of the composition X of any of claims 6 to 9 before, during or after filling step d) to form an isocyanate-based material A which is a foam, and

f) The housing top plate 102 and the housing bottom plate 102 are sealed to each other to provide a substantially airtight battery housing 101.