Materials, systems, and methods for mitigation of electrical energy storage thermal events

Abstract

This disclosure relates to materials and systems for managing thermal runaway problems in energy storage systems. Example embodiments include a multilayer insulation material. The multilayer insulation material includes at least one insulating layer, at least one compressible pad, and optionally one or more layers, exhibiting good heat dissipation characteristics, good fire resistance, flame retardancy, and / or abrasion resistance, and good performance for use as an insulation layer. This disclosure also relates to a battery module or battery pack having one or more battery cells and the multilayer insulation material arranged in thermal communication with the battery cells.

Description

[Technical Field] [Cross-reference to related applications]

[0001] This application claims the benefit and priority of U.S. Provisional Patent Application No. 63 / 218,205, filed July 2, 2021, entitled “Materials, Systems, and Methods for Mitigation of Electrical Energy Storage Thermal Events”, the contents of which are incorporated herein by reference in their entirety.

[0002] This disclosure generally relates to materials and systems for preventing or mitigating thermal events (such as thermal runaway) in energy storage systems. In particular, this disclosure provides multilayer insulation materials comprising at least one insulating layer, at least one compressible pad, and optionally one or more layers, which have good heat dissipation properties, good fire resistance, flame retardancy, and / or abrasion resistance properties, and / or good performance for use as insulation layers. This disclosure further relates to battery modules or battery packs having one or more battery cells including the multilayer insulation material, and systems including such battery modules or battery packs. [Previous Technology]

[0003] Rechargeable batteries (such as lithium-ion batteries) are widely used in electric drive and energy storage systems. Compared with conventional batteries, lithium-ion batteries (LIBs) are widely used to power portable electronic devices such as mobile phones, tablets, laptops, power tools, and other high-current devices such as electric vehicles due to their high operating voltage, low memory effect, and high energy density. However, safety is an issue because LIBs are prone to catastrophic failure under "abuse conditions" (e.g., when rechargeable batteries are overcharged (charged beyond the design voltage), over-discharged, operated or exposed to high temperature and high pressure). Therefore, the narrow operating temperature range and charge / discharge rate limit the use of LIBs, as they may fail due to rapid self-heating or thermal runaway events when subjected to conditions outside their design window.

[0004] As shown in Figure 1, the electrochemical cell of a lithium-ion battery (LIB) mainly consists of a positive electrode, a negative electrode, an electrolyte capable of conducting lithium ions, a separator separating the positive and negative electrodes, and a current collector. LiCoO2, LiFePO4, LiMn2O4, Li2TiO3, LiNi0.8Co0.15Al0.05O2 (NCA), and LiNi1 / 3Co1 / 3Mn1 / 3O2 (NMC) are six widely used cathode materials in lithium-ion batteries. These six types of batteries occupy a large market share in today's battery market. The electrolyte is composed of lithium salts dissolved in specific solvents (mainly including ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and propylene carbonate (PC)). These lithium salts are typically selected from LiClO4, LiPF6, LiBF4, and LiBOB. The separator material is usually a polyolefin-based resin material. In commercial lithium-ion batteries, polypropylene (PP) and polyethylene (PE) microporous membranes are commonly used as separators. Aluminum foil is typically used as the current collector for the positive electrode, while copper foil is used for the negative electrode. Carbon-based materials (including hard carbon, carbon nanotubes, and graphene) are currently the primary choice for most negative electrodes in commercial lithium-ion batteries; other novel negative electrode materials (such as titanium-based oxides, alloy / undelloy materials, and conversion materials) have also been studied and have shown good thermal and electrochemical properties.

[0004] [LIB Operation under Normal Conditions]

[0005] Under normal operation, lithium ions move from one electrode to another through the electrolyte and separator by diffusion and migration.

[0006] Charging the LIB causes lithium ions in the electrolyte solution to migrate from the cathode through the separator and self-insert into the anode (Figure 2). Charge-balancing electrons also move to the anode, but via external circuitry in the charger. During discharge, the reverse process occurs, and electrons flow through the powered device (Figure 2). During this process, heat is generated within the battery through three main mechanisms. The first is reversible heat, caused by entropy changes associated with redox reactions occurring during lithiation (discharge) and delithiation (charging). Reversible heat is also known as entropy heat. The second mechanism is irreversible heat associated with electrode polarization caused by overpotentials in the battery. Finally, there is irreversible heat associated with ohmic losses, called Joule heating. Joule heating is attributed to the movement of lithium ions and electrons within the battery. Under normal conditions, the self-generated heat is extremely low, usually negligible, and can be easily dissipated through good battery design or a battery thermal management system. However, under abuse conditions, several side reactions can occur, leading to thermal runaway. Understanding the causes of thermal runaway can guide the design of functional materials to improve the safety and reliability of LIBs.

[0006] [Overview of Thermal Runaway and its Propagation]

[0007] When the internal reaction rate increases to the point that the heat generated exceeds the recoverable heat, thermal runaway may occur, leading to a further increase in both the reaction rate and heat generation. During thermal runaway, high temperatures trigger a series of exothermic reactions within the battery, causing the battery temperature to rise rapidly. In many cases, when thermal runaway occurs in a battery cell, the generated heat rapidly heats the cells adjacent to the cell experiencing the runaway. Each cell involved in the thermal runaway reaction contains additional energy to continue the reaction, causing thermal runaway to propagate within the battery pack (Figure 3), ultimately leading to a fire or explosion. Rapid heat dissipation and effectively blocking heat transfer paths are effective countermeasures to reduce the hazards caused by the propagation of thermal runaway.

[0007] [Causes of Thermal Runaway - Abuse]

[0008] Thermal runaway can be triggered by various forms of abuse, including mechanical abuse, electrical abuse, and thermal abuse (Figure 3). Each type of abuse can induce an internal short circuit (ISC) in the battery, leading to an increase in temperature. Abuse conditions can begin externally or internally. For example, service-induced stress, aging, design errors (e.g., configuration parameters such as battery spacing), battery interconnection type, battery form factor, manufacturing, operation, and maintenance are internal factors that can cause various forms of abuse. External factors include damage or injury to the LIB, such as that caused by drops or battery penetration.

[0008] [Misuse of Machinery]

[0009] Mechanical abuse is primarily caused by mechanical forces and usually occurs due to external factors (e.g., severe car accidents, including collisions, crushing, penetration, and bending). When a battery or battery pack is impacted or collides, potential damage to the battery's internal structure can occur, including rupture of the separator and leakage of flammable electrolytes, triggering ISC and subsequently leading to thermal runaway. Destructive deformation and displacement caused by applied forces are two common characteristics of mechanical abuse. Battery packs are very likely to deform during a car crash. The layout of the battery pack in an electric vehicle affects its crash response. Deformation of the battery pack can lead to dangerous consequences: the battery separator may be torn, resulting in an internal short circuit (ISC); flammable electrolytes may leak and potentially cause a fire. Penetration is another common phenomenon that can occur during a vehicle collision. Compared to crushing, when penetration begins, it can trigger a violent ISC instantaneously. Mechanical damage and electrical short circuits occur simultaneously, and penetration abuse can be more severe than simple mechanical or electrical abuse.

[0009] [Electro-electric abuse]

[0010] Electrical abuse mainly includes internal or external short circuits of LIB, overcharging, and over-discharging.

[0011] Internal short circuits occur in more than 90% of abuse situations. Broadly speaking, an internal short circuit occurs when the cathode and anode come into contact with each other due to the failure of the battery separator. Internal short circuits can be caused by (1) mechanical abuse, when the separator is ruptured due to penetration or compression; (2) electrical abuse, when the separator is punctured by dendrite growth (Fig. 4); and (3) thermal abuse, when the separator collapses at high temperatures.

[0012] An external short circuit is formed when electrodes with a voltage difference are connected through a conductor. External short circuits in the battery pack can be caused by deformation during a vehicle collision, water immersion, conductor contamination, or electric shock during maintenance. Unlike penetration, the heat released on the circuitry of an external short circuit typically does not heat the battery. An external short circuit can lead to a large current and high heat generation in the battery, primarily due to ohmic heat. When the temperature begins to exceed approximately 70°C, the battery begins to rupture. This can trigger venting and electrolyte leakage.

[0013] Overcharging can be defined as charging a battery beyond its design voltage. Overcharging can be triggered by high specific current densities, aggressive charging curves, etc., which can lead to a series of problems, including lithium metal deposition on the anode, which seriously affects the electrochemical performance and safety of the battery; decomposition of the cathode material, releasing oxygen; and decomposition of organic electrolytes, releasing heat and gaseous products (H2, hydrocarbons, CO, etc.). The overcharging process can be divided into three stages. In the first stage, (1) the voltage and temperature are unaffected and remain essentially unchanged. In the second stage, (2) lithium dendritic deposition occurs on the voltage plateau. And in the third stage, (3) with the generation of heat and gas, the voltage drops sharply, causing thermal runaway of the battery.

[0014] Over-discharge is another possible form of electrical abuse. Voltage inconsistencies between cells within a battery pack are generally unavoidable. Therefore, if the battery management system cannot monitor the voltage of any individual cell, the cell with the lowest voltage will be over-discharged. The mechanism of over-discharge abuse differs from others, and the potential hazards may be underestimated. During over-discharge, the cell with the lowest voltage in the battery pack can be forced to discharge by other cells connected in series. During forced discharge, the electrodes reverse and the cell voltage becomes negative, leading to abnormal heat generation in the over-discharged cell.

[0014] [Heat Abuse]

[0015] Thermal abuse is typically triggered by overheating. Overheating in lithium-ion batteries can be caused by mechanical abuse, electrical abuse, and contact loss in connectors. Normally, LIBs are stable at operating temperatures; however, above certain temperatures, LIB stability becomes unpredictable, and at high temperatures, chemical reactions within the battery casing produce gases, leading to increased internal pressure. These gases can further react with the cathode, releasing more heat and generating heat within or near the battery, which can ignite the electrolyte in the presence of oxygen. When the electrolyte burns, oxygen is produced, further promoting combustion. To some extent, the pressure buildup within the battery casing can cause it to rupture. The escaped gases may ignite and burn.

[0016] Thermal runaway caused by mechanical, electrical, and thermal abuse conditions may induce continuous heat generation, thus increasing the internal temperature of the battery. As the temperature increases, a series of chain reactions may occur at different stages. Thermal runaway follows a chain reaction mechanism, such as physical and / or chemical processes, during which the decomposition reactions of battery component materials occur one after another (Figure 3).

[0016] [Overview of Chain Reactions During Thermal Runaway]

[0017] Understanding the evolution of these physical and / or chemical processes helps in developing mitigation strategies for thermal runaway of LIBs. LIBs can have different thermal runaway triggers in different temperature states or modes (Figure 5), including state I: low temperature (<0°C), state II: normal temperature (0~90°C), and state III: high temperature (>90°C).

[0018] In State I, the LIB cannot function effectively because the low temperature reduces the electrochemical reaction rate. At lower temperatures, battery performance deteriorates sharply due to the reduced activity of the electrode materials and the decreased diffusion rate of lithium ions in the electrolyte. The consequences of the slowed chemical reaction at low temperatures include undesirable lithium deposition, plating, and dendritic growth. Dendritic growth is a tree-like structure that can form on the lithium plating in the battery. It can rapidly penetrate the battery separator (a porous plastic membrane located between the anode and cathode of the battery) (Figure 4). Lithium deposition and dendritic growth within the battery are considered major contributing factors to thermal runaway at low temperatures. It is not desirable to be bound by theory, but it is believed that undesirable lithium deposition and dendritic growth may cause ISC in the battery, leading to thermal runaway.

[0019] In State II (normal temperature operation), heat generation is minimal compared to that generated during thermal runaway. Heat generation during this operating state is primarily caused by lithium-ion diffusion in the solid-liquid phase, electrochemical reactions at the solid-liquid interface, and side reactions. This heat generation can cause temperature rise and internal temperature differences within the battery, which may affect the lifespan and safety of the lithium-ion battery. During State II, initial overheating can occur due to at least one of the aforementioned internal or external triggers, such as overcharging, exposure to excessively high temperatures, external short circuits due to wiring faults, or internal short circuits due to battery defects. When initial overheating begins, as the temperature rises towards 90°C, battery operation changes from a normal state to an abnormal state. When the temperature exceeds 40°C, the lifespan of the lithium-ion battery may be shortened due to accelerated side reactions, and when the temperature approaches 90°C or higher, it can trigger the decomposition of the solid electrolyte interphase (SEI) film, which is defined as the onset of thermal runaway. During the first few charging cycles, SEI is generated on the anode of the lithium-ion battery. The SEI provides a passivation layer on the anode surface, which inhibits further electrolyte decomposition and provides the long calendar lifetime required for many applications. Initial decomposition of the SEI is considered the first side reaction occurring during a fully thermal runaway process. Initial decomposition of the SEI occurs between 80 and 120 °C, peaking at approximately 100 °C. The onset temperature can be below 80 °C, as Wang et al. (Thermochim. Acta 437 (2005) 12-16) reported that SEI decomposition can begin at temperatures as low as 57 °C.

[0019] [SEI Decomposition]

[0020] When state III begins, the internal temperature rises rapidly, leading to the decomposition of the SEI film. The SEI layer is mainly composed of stable (e.g., LiF and Li2CO3) and metastable (e.g., polymers, ROCO2Li, (CH2OCO2Li)2, and ROLi) components. However, the metastable components can decompose exothermically at approximately >90°C, releasing flammable gases and oxygen. The decomposition of the SEI film is considered the beginning of thermal runaway, which then triggers a series of exothermic reactions.

[0021] As the SEI decomposes, the temperature rises, and the lithium metal or lithium intercalation in the anode reacts with the organic solvent in the electrolyte, releasing flammable hydrocarbon gases (ethane, methane, and others). This is an exothermic reaction, driving the temperature to rise further.

[0021] [Decomposition of the isolation membrane]

[0022] When T>~130℃, the polyethylene (PE) / polypropylene (PP) separator begins to melt, which further worsens the situation and causes a short circuit between the cathode and anode. Although the melting of the PE / PP separator is a thermal adsorption process, the ISC caused by the melting of the separator will further worsen the thermal runaway process.

[0022] [Gas Emissions and Electrolyte Decomposition]

[0023] When T>~180℃, the heat generated by the ISC causes the lithium metal oxide cathode material to decompose and release oxygen. The decomposition of the cathode is also highly exothermic, further increasing the temperature and pressure, thus further accelerating the reaction. Subsequently, the heat accumulation and gas release (oxygen and flammable gases) will induce the combustion and explosion of the lithium-ion battery.

[0024] During thermal runaway, the heat generated by ISC accounts for only 2%, while the heat generated by chemical reactions accounts for 98%, including the decomposition of the SEI layer and the decomposition of the electrolyte. The largest proportion of heat generation is caused by the rapid redox reaction between the cathode and anode, approximately 48%, while the heat generated by other chemical reactions in the anode, cathode, and electrolyte is much smaller. The smallest heat generation is the decomposition of the SEI film.

[0024] [The need for strategies to mitigate thermal runaway]

[0025] Based on the understanding of the mechanisms leading to battery thermal runaway, numerous methods are being researched to reduce safety hazards through the rational design of battery components. To prevent such cascading thermal runaway events, battery modules (LIBs) are typically designed to maintain sufficiently low energy storage, or to use sufficient insulating material between batteries within a battery module or battery pack to protect these batteries from thermal events that may occur in adjacent batteries, or a combination of both. The former severely limits the energy that can be stored in such devices. The latter limits the spacing between batteries, thereby limiting the effective energy density. Effective insulation and heat dissipation strategies are needed to mitigate the possibility of thermal runaway in LIBs.

[0025] [Current heat dissipation methods used in LIBs]

[0026] Several different methods are currently used to maximize energy density while preventing cascading thermal runaway. One method involves incorporating sufficient insulation between batteries or battery clusters. This method is generally considered for safety reasons; however, in this method, the heat-holding capacity of the insulating material and the required insulation volume determine the upper limit of the achievable energy density. Another method involves using phase change materials. These materials undergo an endothermic phase change when a certain high temperature is reached. This endothermic phase change absorbs part of the heat generated, thereby cooling a localized area. Typically, for electrical storage devices, these phase change materials rely on hydrocarbon materials, such as waxes and fatty acids. These systems are effective in cooling, but they are themselves flammable, thus detrimental to preventing thermal runaway should a fire occur within the storage device. Incorporating expandable materials is another strategy to prevent cascading thermal runaway. These materials expand above a specified temperature, producing carbon, which is designed to be lightweight and provide thermal insulation when needed. These materials effectively provide insulation benefits, but the expansion of the materials must be considered in the design of the storage device.

[0026] [The need for new insulation layers to meet the mechanical requirements of LIB systems]

[0027] The expansion of the anode and cathode during charging and discharging can lead to dimensional changes (expansion) in the battery. For example, silicon exhibits a typical volume change of up to 300% during intercalation, and graphite has a volume expansion of approximately 10%. This change has both reversible and irreversible components, the magnitude of which depends on precise battery chemistry. Reversible changes in battery thickness depend solely on the battery's state of charge (SOC) and can result in an increase in thickness exceeding 2%. Irreversible expansion of the battery is related to an increase in internal pressure and is caused by the formation of the SEI. The largest component of this change occurs during the first charging cycle, when the SEI initially forms, but the expansion continues throughout the battery's lifetime.

[0028] Although extensive research has been conducted to invent new materials with good thermal properties to prevent thermal runaway problems, the mechanical properties of these materials have not received sufficient attention, despite their importance. For example, effective thermal insulation layers are needed between batteries within a battery module or battery pack, providing resistance to compressive deformation to accommodate continuous battery expansion throughout the battery's lifespan. Furthermore, during the initial assembly of the battery module, low loads of 1 MPa or less are typically applied to the materials between the batteries. As the batteries within the battery module or battery pack expand or grow during charge / discharge cycles, loads up to approximately 5 MPa may be applied to the materials between the batteries. Therefore, the compressibility, compressive elasticity, and compliance of materials (e.g., thermal insulation layers between batteries) are important characteristics.

[0029] Therefore, a new type of insulation layer is needed to meet the mechanical requirements of the LIB system in order to provide effective insulation under thermal runaway conditions and effective heat dissipation under normal conditions. [Summary of the Invention]

[0030] The purpose of this disclosure is to eliminate or mitigate at least one drawback of the prior methods and materials described above, in order to prevent or mitigate thermal runaway in rechargeable batteries (e.g., lithium-ion batteries). The multilayer materials provided herein are designed to enhance the safety of lithium-ion batteries.

[0031] In particular, the purpose of this disclosure is to provide a multilayer material for use as an insulation layer in an energy storage system to solve the problem of heat transfer in a battery module or battery pack, and to prevent or mitigate heat transfer when a battery experiences thermal runaway. The unique configuration of the multilayer material disclosed herein can help solve the problem of heat transfer between batteries.

[0032] This mitigation strategy can be applied at the material, battery, and system levels to ensure the overall safety of energy storage systems using rechargeable batteries (e.g., lithium-ion batteries). The multilayer materials disclosed herein can perform at least one of the following mitigation steps: (1) reducing the likelihood of abuse, (2) eliminating abuse in the event of abuse, (3) enhancing the thermal stability of the battery cells to prevent abuse, (4) reducing the energy released under normal operating conditions and thermal runaway, and (5) mitigating the spread of hazards and confining damage to a limited area.

[0033] Another object of this disclosure is to provide a battery module or battery pack that includes a multilayer material according to the present invention, the multilayer material protecting the battery pack from thermal damage caused by thermal runaway of a battery and ensuring the safe design of the battery pack.

[0034] In a general embodiment, this disclosure provides novel multilayer materials comprising an aerogel composition (e.g., a reinforced aerogel composition), which are durable and easy to handle, have good resistance to heat and fire propagation, while minimizing the thickness and weight of the material used, and have good compressibility, compressive elasticity, and conformability. For example, a multilayer material according to the embodiment disclosed herein may include at least one insulating layer comprising an aerogel composition or a reinforced aerogel composition.

[0035] In a general sense, the multilayer materials disclosed herein can be used to separate, insulate, and protect battery cells or battery assemblies having batteries of any configuration, such as pouch cells, cylindrical cells, prismatic cells, and including or comprising any such battery packs and modules. The multilayer materials disclosed herein can be used in rechargeable batteries (e.g., lithium-ion batteries), solid-state batteries, and any other energy storage devices or technologies requiring separation, insulation, and protection.

[0036] In a general embodiment, this disclosure aims to provide a battery module and a battery pack for simultaneously improving the heat dissipation performance and thermal runaway protection performance of a power battery. Referring to FIG6, in an electric drive and energy storage system, a number of batteries 100 are typically packaged together in a pre-selected configuration (e.g., in parallel, series, or combined) to form a battery module 200. Accordingly, a number of such battery modules can be combined or connected to form various battery packs 300 known in the art. During operation and discharge, such batteries, battery modules, or battery packs typically generate or produce a large amount of heat, which can severely and adversely affect the resulting performance. Therefore, in order to maintain the desired or optimal performance of such batteries or the battery modules or battery packs formed therefrom, it is generally important to keep the temperature of such batteries, battery modules, or battery packs within a narrow specified range. The purpose of this disclosure is to keep the temperature of such batteries, battery modules, or battery packs within an optimal range.

[0037] In addition to maintaining the battery temperature within a specified range, the aim is also to maintain the structural integrity of the battery. The materials within the battery must possess both compliance and elasticity to accommodate volume changes during battery operation. In some embodiments, the materials must be flame-retardant or fire-resistant to maintain structural integrity after or during a thermal event.

[0038] In one embodiment, a multilayer material for use as an insulation layer in an energy storage system is provided herein, comprising: a core portion comprising a layered assembly consisting of at least one insulating layer and at least one heat-capacitance layer, the insulating layer and the heat-capacitance layer being alternately stacked in a direction perpendicular to their maximum surface; and an outer portion disposed outside the core portion, the outer portion comprising: at least one sacrificial material layer including a compressible pad, and at least one encapsulating material layer selected from polymers, elastomers, or combinations thereof. In some embodiments, the sacrificial material layer has a 25% compressive force deflection (CFD) at about 20 kPa to about 100 kPa (e.g., from about 27 kPa to about 55 kPa).

[0039] In another embodiment, a multilayer material for use as an insulation layer in an energy storage system is provided herein, comprising: a core portion comprising a layered assembly consisting of at least one insulating layer and at least one thermally conductive layer, the insulating layer and the thermally conductive layer being alternately stacked in a direction perpendicular to their maximum surface; and an outer portion disposed on the exterior of the core portion, the outer portion comprising at least one sacrificial material layer and at least one encapsulating material layer selected from at least one of polymers, elastomers, or combinations thereof. In some embodiments, the sacrificial material layer has a 25% compressive force deflection (CFD) at about 20 kPa to about 100 kPa (e.g., from about 27 kPa to about 55 kPa).

[0040] In one embodiment, a multilayer material for use as an insulation layer in an energy storage system is provided herein, comprising: a core portion including at least one insulating layer; and an outer portion disposed on the exterior of the core portion, the outer portion comprising: at least one sacrificial material layer including a compressible pad having a compressive modulus of about 1 MPa to about 12 MPa, and at least one encapsulating material layer selected from polymers, elastomers, or combinations thereof, wherein the encapsulating material layer is sandwiched between the core portion and the sacrificial material layer of the outer portion. In some embodiments, the core portion further includes at least one heat capacity layer having a specific heat capacity of at least about 200 J / (kg-K). In some embodiments, the core portion comprises a layered assembly consisting of at least one insulating layer and at least one heat capacity layer, the insulating layer and the heat capacity layer being alternately stacked along a direction perpendicular to their maximum surface area. In some embodiments, the core portion further includes at least one thermally conductive layer having a thermal conductivity of at least about 200 mW / mK along its in-plane dimension. In some embodiments, the core portion includes a layered assembly consisting of at least one insulating layer and at least one thermally conductive layer, the insulating layer and the thermally conductive layer being alternately stacked along a direction perpendicular to their maximum surface.

[0041] In another embodiment, a multilayer material for use as an insulation layer in an energy storage system is provided herein, comprising: a core layer having two sides, comprising at least one compressible material layer having a compressive modulus of about 1 MPa to about 12 MPa and optionally at least one thermally conductive layer and / or at least one thermally capacitive layer; two insulating layers having a thermal conductivity of less than about 50 mW / mK at 25°C and less than about 60 mW / mK through the thickness dimension of the insulating layer, wherein the core layer is sandwiched between the two insulating layers, wherein the optional at least one thermally conductive layer has an in-plane thermal conductivity of at least about 200 mW / mK, and wherein the optional at least one heat-fusible layer has a specific heat capacity of at least about 200 J / (kg-K), and wherein the multilayer material is selectively encapsulated in an encapsulation material layer selected from at least one of polymers, elastomers, or combinations thereof. In some embodiments, the core layer further comprises a flame-retardant layer. In some embodiments, the core layer does not have the optional at least one thermally conductive layer and does not have the optional at least one heat-capacity layer. In some embodiments, the core layer includes the optional at least one thermally conductive layer but does not have the at least one heat-capacity layer. In some embodiments, the core layer includes two thermally conductive layers and a compressible material layer, wherein the compressible material layer is sandwiched between the two thermally conductive layers. In some embodiments, the core layer includes the optional at least one heat-capacity layer but does not have the at least one thermally conductive layer. In some embodiments, the core layer includes two heat-capacity layers and a compressible material layer, wherein the compressible material layer is sandwiched between the two heat-capacity layers. In some embodiments, the core layer includes a heat-capacity layer and two compressible material layers, wherein the heat-capacity layer is sandwiched between the two compressible material layers. In some embodiments, the multilayer material complex includes two heat-capacity layers, wherein each heat-capacity layer is disposed on the outer surface of each insulating layer.

[0042] Any of the above-described embodiments may include one or more of the following features. For example, in some embodiments, the encapsulation material layer is sandwiched between the core portion and the sacrificial material layer. In some embodiments, the sacrificial material layer is sandwiched between the core portion and the encapsulation material layer. In some embodiments, the sacrificial material layer comprises a material selected from the group consisting of siloxanes, polyolefins, polyurethanes, phenolic resins, melamine, cellulose acetate, and polystyrene. In some embodiments, the sacrificial material layer is in the form of foam. In one or more embodiments, the chemical decomposition initiation temperature of the sacrificial material layer is in the range of about 200°C to about 400°C.

[0043] In some embodiments, the outer portion further includes a layer made of a material selected from the group consisting of abrasion-resistant materials, intumescent materials, fire-resistant materials, flame-retardant materials, or combinations thereof.

[0044] In some embodiments, the heat capacity layer has a specific heat capacity of at least about 200 J / (kg-K). In some embodiments, the heat capacity layer is a phase change material. In some embodiments, the heat capacity layer comprises stainless steel.

[0045] In some embodiments, the encapsulation material layer is a polyethylene terephthalate layer.

[0046] In some embodiments, the encapsulation material layer further includes a metal layer disposed between the encapsulation layer and the core portion.

[0047] In some embodiments, the insulating layer has a thermal conductivity of less than about 50 mW / mK at 25°C and less than about 60 mW / mK throughout its thickness dimension. In some embodiments, the insulating layer comprises aerogel. In some embodiments, the insulating layer further comprises a material selected from the group consisting of mica, microporous silica, ceramic fibers, mineral wool, and combinations thereof. In some embodiments, the insulating layer does not have aerogel, and the insulating layer comprises a material selected from the group consisting of mica, microporous silica, ceramic fibers, mineral wool, and combinations thereof.

[0048] In some embodiments, the thermally conductive layer has a thermal conductivity of at least about 200 mW / mK along its in-plane dimension. In some embodiments, the thermally conductive layer system comprises at least one layer of a metal, carbon, a thermally conductive polymer, or a combination thereof. In some embodiments, the thermally conductive layer system is a phase change material. In some embodiments, the thermally conductive layer system is a metal selected from aluminum, copper, or steel. In some embodiments, the thermally conductive layer conducts heat away from local heat loads, preferably to the environment. In some embodiments, the thermally conductive layer system is in the form of a group selected from meshes, sheets, perforated sheets, foils, and perforated foils. In some embodiments, the thermal conductivity through the thickness dimension of the insulating layer (e.g., aerogel) at 25°C remains unchanged or increases insignificantly under loads up to about 5 MPa. In some embodiments, the thermal conductivity across the thickness of the insulating layer is less than about 50 mW / mK at 25°C under loads up to about 5 MPa. In some embodiments, the thermally conductive layer comprises aluminum.

[0049] In some embodiments, the insulating layer comprising the aerogel further includes a reinforcing material. In some embodiments, the reinforcing material is a fiber selected from organic polymer-based fibers, inorganic fibers, carbon-based fibers, or combinations thereof. In some embodiments, the fiber is in the form of discrete fibers, woven materials, dry-laid nonwoven materials, wet-laid nonwoven materials, needle-punched nonwoven materials, cotton wadding, nets, mats, felts, and / or combinations thereof. In some embodiments, the inorganic fiber is selected from glass fibers, rock fibers, metal fibers, boron fibers, ceramic fibers, basalt fibers, or combinations thereof. In one or more embodiments, the aerogel comprises a silica-based aerogel. In one or more embodiments, the aerogel includes one or more additives, the additives comprising at least about 5 to 40 weight percent of the aerogel, preferably at least about 5 to 20 weight percent of the aerogel, more preferably at least about 10 to 20 weight percent of the aerogel. In some embodiments, the one or more additives include fire-retardant additives. In some embodiments, the one or more additives include a light-blocking agent selected from B4C, diatomaceous earth, manganese ferrite, MnO, NiO, SnO, Ag2O, Bi2O3, TiC, WC, carbon black, titanium dioxide, ferrotitanium, zirconium silicate, zirconium oxide, iron oxide (I), iron oxide (III), manganese dioxide, ferrotitanium (ilmenite), chromium oxide, or mixtures thereof. In some embodiments, the one or more additives include a light-blocking agent comprising silicon carbide. In some embodiments, the one or more additives include a combination of a fire-retardant additive and a light-blocking agent. In one or more embodiments, the aerogel has a density in the range of about 0.25 g / cc to about 1.0 g / cc. In some embodiments, the aerogel has a flexural modulus of about 2 MPa to about 8 MPa. In some embodiments, the aerogel has a compression set in the range of about 10% to about 25% at about 70°C. In some embodiments, the aerogel exhibits compressibility, and this compressibility at 25% strain is between about 40 kPa and about 180 kPa. In one or more embodiments, the aerogel is in the form of monoliths, microbeads, particles, granules, powders, films, sheets, or combinations thereof.

[0050] In some embodiments, the thermally conductive layer system comprises at least one layer of a metal, carbon, a thermally conductive polymer, or a combination thereof. In some embodiments, the thermally conductive layer system is a phase change material. In some embodiments, the thermally conductive layer system is a metal selected from aluminum, copper, or steel. In some embodiments, the thermally conductive layer conducts heat away from the local heat load, preferably to the environment. In some embodiments, the thermally conductive layer system is in the form of a group selected from mesh, sheet, perforated sheet, foil, and perforated foil. In some embodiments, the thermal conductivity through the thickness dimension of the insulating layer (e.g., aerogel) remains unchanged or increases insignificantly under loads up to about 5 MPa at 25°C. In some embodiments, the thermal conductivity through the thickness dimension of the insulating layer is less than about 50 mW / mK at 25°C under loads up to about 5 MPa.

[0051] In another embodiment, this document provides a multilayer material for use as an insulation layer in an energy storage system. The multilayer material includes a core portion comprising a layered assembly including at least one insulating layer and at least one heat-capacitance layer. An outer portion is disposed outside the core portion, the outer portion including at least one sacrificial material layer, wherein the sacrificial material layer includes a compressible pad having 25% compressive force deflection (CFD) at about 20 kPa to about 100 kPa (e.g., from about 27 kPa to about 55 kPa). The heat-capacitance layer has a specific heat capacity of at least about 200 J / (kg-K), and wherein the insulating layer has a thermal conductivity of less than about 50 mW / mK at 25°C and less than about 60 mW / mK through its thickness dimension at 600°C.

[0052] In another embodiment, this document provides a multilayer material for use as an insulation layer in an energy storage system. The multilayer material includes a core portion comprising a layered assembly including at least one insulating layer and at least one thermally conductive layer. An outer portion is disposed on the exterior of the core portion, the outer portion including at least one sacrificial material layer having a compressive force deflection (CFD) of 25% at about 20 kPa to about 100 kPa (e.g., from about 27 kPa to about 55 kPa). The thermally conductive layer has a thermal conductivity of at least about 200 mW / mK along its in-plane dimension. The insulating layer has a thermal conductivity of at least about 200 mW / mK along its in-plane dimension, and wherein the insulating layer has a thermal conductivity of less than about 50 mW / mK at 25°C and less than about 60 mW / mK through its thickness at 600°C.

[0053] In one embodiment, the multilayer material used as an insulation layer in an energy storage system includes a core layer comprising at least one compressible material layer having a compressive modulus of about 1 MPa to about 12 MPa, and at least one thermally conductive layer and / or at least one thermally capacitive layer. Furthermore, the multilayer material includes two insulating layers having a thermal conductivity of less than about 50 mW / mK at 25°C and less than about 60 mW / mK through the thickness of the insulating layers. The core layer is sandwiched between the two insulating layers. The multilayer material is selectively encapsulated in an encapsulation material.

[0054] In one embodiment, the use of multilayer materials according to various embodiments of any of the above embodiments in a battery pack comprising a plurality of single-cell cells or battery cell modules is provided herein for thermally separating the single-cell cells or battery cell modules from each other. In some embodiments, a runaway event occurring in one or more battery cells or battery cell modules of a portion of the battery will not cause damage to the battery cells or modules in the portion of the battery separated from that portion by the multilayer material according to any of the above embodiments.

[0055] In another embodiment, the multilayer material provided herein according to various embodiments of any of the above embodiments is located in a battery pack comprising a plurality of individual cell units or battery cell modules, so as to thermally separate the individual cell units or battery cell modules from each other.

[0056] In one embodiment, a battery module is provided herein, comprising: a first battery cell having a first surface; a second battery cell having a second surface opposite to the first surface; and a multilayer material according to various embodiments of any of the above embodiments, disposed between the first and second surfaces. In some embodiments, the multilayer material covers at least about 80% of the surface area of ​​the opposite first and second surfaces.

[0057] In another embodiment, a battery module is provided herein, comprising: at least one battery cell, and a multilayer material according to various embodiments of any of the above embodiments, wherein the multilayer material is disposed on the surface of the at least one battery cell or on the surface of the battery module.

[0058] In one embodiment, a battery pack is provided herein, comprising a plurality of batteries and spacers disposed between two adjacent batteries or two adjacent modules, wherein the spacers comprise multilayer materials according to various embodiments of any of the above embodiments.

[0059] The battery module or battery pack according to any of the above-described forms further includes a cooling system configured to remove heat from the battery pack. In some embodiments, at least one layer of the multilayer material is in thermal communication with the cooling system. In some embodiments, the thermally conductive layer is in thermal communication with the cooling system.

[0060] In another embodiment, a device or vehicle is provided herein, comprising a battery module or battery pack according to any of the above embodiments. In some embodiments, the device is a laptop computer, PDA, mobile phone, tag scanner, audio device, video device, display panel, camera, digital camera, desktop computer, military portable computer, military telephone, laser rangefinder, digital communication device, intelligence gathering sensor, electronic integrated clothing, night vision device, power tool, calculator, radio, remote control device, GPS device, handheld and portable television, car starter, flashlight, acoustic device, portable heating device, portable vacuum cleaner, or portable medical tool. In some embodiments, the vehicle is an electric vehicle.

[0061] In one or more embodiments, the multilayer material according to any of the above-described states has an average thickness between about 2 mm and about 10 mm in an uncompressed state.

[0062] Compared to existing thermal runaway mitigation strategies, the multilayer materials described herein offer one or more advantages. The multilayer materials described herein can minimize or eliminate battery thermal runaway propagation without significantly affecting the energy density and assembly cost of the battery module or battery pack. The multilayer materials disclosed herein offer good compressibility, compressive elasticity, and compliance properties to accommodate continuous battery expansion throughout battery life, while exhibiting good thermal properties under normal operating conditions and under thermal runaway conditions. The multilayer materials described herein are durable and easy to handle, have good resistance to heat propagation and fire propagation, while minimizing the thickness and weight of the materials used, and possess good compressibility, compressive elasticity, and compliance properties. [Simplified Explanation of the Diagram]

[0063] After summarizing this disclosure, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and in which:

[0064] Figure 1 shows a schematic diagram of the electrochemical cell of a lithium-ion battery;

[0065] Figure 2 illustrates a schematic diagram of the charging-discharging process in a lithium-ion battery.

[0066] Figure 3 schematically illustrates the thermal runaway abuse situation and thermal runaway propagation process in the battery module.

[0067] Figure 4 is a schematic diagram of the dendritic growth on the lithium coating in the battery.

[0068] Figure 5 schematically illustrates the three stages leading to thermal runaway.

[0069] Figure 6 schematically illustrates the battery cell, battery module and battery pack.

[0070] Figure 7 schematically illustrates a multilayer material according to a specific embodiment disclosed herein.

[0071] Figure 8 schematically illustrates a multilayer material according to a specific embodiment disclosed herein.

[0072] Figures 9A-E schematically illustrate multilayer materials according to specific embodiments disclosed herein.

Implementation Method

[0073] In the following detailed description of preferred embodiments, reference is made to the accompanying drawings, which constitute part of these embodiments and are illustrated by way of example of specific embodiments by which this disclosure may be implemented. It should be understood that other embodiments may be used and structural changes may be made without departing from the scope of this disclosure.

[0074] This disclosure relates to multilayer materials for managing thermal runaway problems in energy storage systems and systems including such multilayer materials. Example embodiments include multilayer materials comprising at least one insulating layer, at least one compressible pad, and optionally one or more layers, which have good heat dissipation properties, good fire resistance, flame retardancy, and / or abrasion resistance properties, and good performance for use as a thermal insulation layer. This disclosure further relates to a battery module or battery pack having one or more battery cells and the multilayer thermal insulation material arranged in thermal communication with the battery cells.

[0075] One or more insulating layers of the multilayer materials disclosed herein may include an aerogel composition or a reinforced aerogel composition. The thermal resistance of aerogel materials is known to be two to six times that of other common types of insulating materials (e.g., foam, glass fiber, etc.). Aerogels can increase effective shielding and thermal insulation without significantly increasing insulation thickness or adding extra weight. Aerogels are known to be a class of structures with low density, open-cell structure, large surface area, and nanoscale pore size.

[0076] The multilayer materials according to the embodiments of this disclosure, and the multilayer materials comprising aerogel compositions, provide good compressibility, compressive elasticity, and compliance. When used as an insulating layer between batteries within a battery module, the multilayer material provides resistance to compressive deformation to accommodate battery expansion caused by the degradation and expansion of active materials during the battery's charge / discharge cycle.

[0077] Furthermore, this disclosure provides a battery module or battery pack, comprising: at least one battery cell; and a multilayer material according to embodiments disclosed herein, disposed on the battery cell or the battery module, for example, on the surface of the at least one battery cell or on the surface of the battery module. For example, the battery module or battery pack has an inner surface and an outer surface. In a particular embodiment, the multilayer material is located on the inner surface of the battery module or battery pack. In a particular embodiment, the multilayer material is located on the outer surface of the battery module or battery pack.

[0078] The multilayer materials disclosed herein can have various unique configurations, wherein more than one layer having good thermal and / or mechanical properties is arranged in a specific manner. Figure 7 illustrates an example multilayer material 400 according to an embodiment disclosed herein. In one embodiment, the multilayer material 400 used as an insulation layer in an energy storage system includes: a core portion 700 comprising a layered assembly consisting of insulating layers 470 and 480 and heat capacity layers 430, 440 and / or 450, these layers being alternately stacked in a direction perpendicular to their maximum surface; and an outer portion 600 disposed outside the core portion 700, the outer portion 600 having a sacrificial material layer including a compressible pad. The compressible pads 410 / 460 have a compression modulus of about 1 MPa to 12 MPa. The encapsulation material layer 420 is selected from polymers, elastomers, or combinations thereof. The heat capacity layers 430, 440 and 450 have a specific heat capacity of at least about 200 J / (kg-K). Insulating layers 470 and 480 have thermal conductivity of less than about 50 mW / mK at 25°C and less than about 60 mW / mK at 600°C, extending through the thickness of the insulating layer.

[0079] In some embodiments, insulating layers 470 and 480 are made of the same material. In some embodiments, insulating layers 470 and 480 are made of different materials with different thermal and / or mechanical properties. In some embodiments, heat-capacity layers 430, 440, and 450 are made of the same material. In some embodiments, heat-capacity layers 430, 440, and 450 are made of different materials with different thermal and / or mechanical properties. Compressible pads 410 and 460 may also be made of different or the same materials.

[0080] Figure 8 illustrates a multilayer material 500 according to an embodiment disclosed herein. In one embodiment, the multilayer material 500, used as an insulation layer in an energy storage system, includes: a core portion 700 comprising a layered assembly consisting of insulating layers 470 and 480 and thermally conductive layers 530, 540, and 550, these layers being alternately stacked along a direction perpendicular to their maximum surface. An outer portion 600 is disposed outside the core portion 700. The outer portions 600 each have a sacrificial material layer including a compressible pad. The compressible pads 410 / 460 have a compressive modulus of about 1 MPa to 12 MPa. An encapsulation material layer 420 is selected from polymers, elastomers, or combinations thereof. The thermally conductive layers 530, 540, and 550 have a thermal conductivity of at least about 200 mW / mK along their in-plane dimensions. Insulating layers 470 and / or 480 have thermal conductivity of less than about 50 mW / mK at 25°C and less than about 60 mW / mK at 600°C, extending through the thickness of the insulating layer.

[0081] In some embodiments, the thermally conductive layers 530, 540, and 550 are made of the same material. In some embodiments, the thermally conductive layers 530, 540, and 550 are made of different materials with different thermal and / or mechanical properties.

[0082] In some embodiments, the encapsulation material layer 420 is sandwiched between the core portion 700 and a sacrificial material layer having at least one compressible pad 410 and / or 460, as shown in Figures 7 and 8. In some embodiments, the sacrificial material layer having at least one compressible pad 410 and / or 460 is sandwiched between the core portion 700 and the encapsulation material layer 420.

[0083] The multilayer material according to the embodiments disclosed herein may have an average thickness in the range of about 2 mm to about 10 mm in an uncompressed state. When exposed to external mechanical loads (e.g., loads applied to the materials between the batteries during the initial assembly of the battery module, such as 1 MPa or less), the average thickness of the multilayer material may decrease.

[0084] In the example configuration of the multilayer material shown in FIG9A, the multilayer material 800 used as an insulation layer in an energy storage system comprises: a core layer comprising a compressible pad 410 having a compression modulus of about 1 MPa to about 12 MPa (e.g., 1.5 MPa, 2 MPa, 4 MPa, 5 MPa, 6 MPa, 8 MPa, 9 MPa, 10 MPa, 11 MPa, 11.5 MPa); and two insulating layers 470 and 480 having a thermal conductivity of less than about 50 mW / mK at 25°C and less than about 60 mW / mK through the thickness dimension of the insulating layer. The core layer is sandwiched between the two insulating layers 470 and 480, wherein the multilayer material is selectively encapsulated in an encapsulation material 420 selected from at least one of polymers, elastomers, or combinations thereof.

[0085] In the example configuration of the multilayer material shown in FIG9B, the multilayer material 810 used as an insulation layer in an energy storage system includes a core layer comprising a compressible pad 410 having a compression modulus of about 1 MPa to about 12 MPa and two thermally conductive layers 530 and 540. The multilayer material 801 further includes two insulating layers 470 and 480 having a thermal conductivity of less than about 50 mW / mK at 25°C and less than about 60 mW / mK through the thickness dimension of the insulating layer, wherein the core layer is sandwiched between the two insulating layers 470 and 480, wherein the at least one thermally conductive layer has an in-plane thermal conductivity of at least about 200 mW / mK, and wherein the multilayer material is selectively encapsulated in an encapsulation material 420 selected from at least one of polymers, elastomers, or combinations thereof.

[0086] In the example embodiment shown in FIG9C, the multilayer material 820 used as an insulation layer in an energy storage system includes a core layer comprising a compressible pad 410 having a compression modulus of about 1 MPa to about 12 MPa and two heat-capacity layers 430 and 440. The core layer is sandwiched between two insulating layers 470 and 480, the insulating layers having a thermal conductivity of less than about 50 mW / mK at 25°C and less than about 60 mW / mK through the thickness dimension of the insulating layer. The heat-capacity layers have a specific heat capacity of at least about 200 J / (kg-K). The multilayer material is selectively encapsulated in an encapsulation material 420 selected from at least one of polymers, elastomers, or combinations thereof.

[0087] In the example embodiment shown in FIG9D, the multilayer material 830 used as an insulation layer in an energy storage system includes a core layer having a compressible pad 410 having a compression modulus of about 1 MPa to about 12 MPa and two heat capacity layers 430 and 440. The core layer is sandwiched between two insulating layers 470 and 480 (having a thermal conductivity of less than about 50 mW / mK at 25°C and less than about 60 mW / mK through the thickness dimension of the insulating layer at 600°C). The heat capacity layer has a specific heat capacity of at least about 200 J / (kg-K). The multilayer material 830 further includes two additional heat capacity layers 435 and 445 disposed on the outer surfaces of each insulating layer 470 and 480. The multilayer material is selectively encapsulated in an encapsulation material 420 selected from at least one of polymers, elastomers, or combinations thereof.

[0088] In the example configuration of the multilayer material shown in FIG9E, the multilayer material 840 used as an insulation layer in an energy storage system includes a core layer comprising two compressible pads 410 and 460 (each having a compression modulus of about 1 MPa to about 12 MPa) and a heat capacity layer 430. The core layer is sandwiched between two insulating layers 470 and 480 (having thermal conductivity of less than about 50 mW / mK at 25°C and less than about 60 mW / mK through the thickness dimension of the insulating layer at 600°C). The heat capacity layer has a specific heat capacity of at least about 200 J / (kg-K). The multilayer material is selectively encapsulated in an encapsulation material 420 selected from at least one of polymers, elastomers, or combinations thereof. The heat capacity layer 430 is sandwiched between the two compressible pads 410 and 460.

[0088] Insulation layer

[0089] The insulating layer of the multilayer material described herein is responsible for reliably controlling the heat flow in heat-generating portions of a small space to provide safety and prevent fire propagation for such products in the electronics, industrial, and automotive technology sectors. Insulating layers with superior compressibility can be used to meet these requirements. In many embodiments disclosed herein, the insulating layer itself, or in combination with other layers of the multilayer material, also acts as a flame / fire diversion layer. For example, an insulating layer (e.g., an aerogel layer) combined with a flame-retardant layer (e.g., a metal or mica layer) can protect the underlying layer from flames and / or hot gases, as well as flames / hot gases carrying particulate materials (e.g., materials that may be ejected from the LIB during a thermal runaway event). Alternatively, the insulating layer may itself be resistant to flames and / or hot gases, as well as flames / hot gases carrying particulate materials. An insulating layer (e.g., mica, microporous silica, aerogel) combined with a flame-retardant layer can act as a flame / fire diversion layer. Insulating layers, including aerogels (such as those disclosed in the embodiments herein), are durable and easy to handle, have good resistance to heat and fire propagation, minimize the thickness and weight of the materials used, and have good compressibility, compressive elasticity, and conformability.

[0090] Aerogels are a class of porous materials with open pores. They consist of a framework of interconnected structures within which a corresponding network of pores is integrated, and the interstitial phase within this network is primarily composed of gas, such as air. Aerogels are typically characterized by low density, high porosity, large surface area, and small pore size. Aerogels can be distinguished from other porous materials by their physical and structural properties.

[0091] Therefore, in some embodiments, the insulating layer of the multilayer material disclosed herein includes aerogel. In some embodiments, the insulating layer may further include a material selected from the group consisting of mica, microporous silica, ceramic fibers, mineral wool, and combinations thereof. In some cases, the insulating layer does not have aerogel. In some embodiments, the insulating layer may include a material selected from the group consisting of mica, microporous silica, ceramic fibers, mineral wool, and combinations thereof.

[0092] In a particular embodiment, the insulating layer disclosed herein has a thermal conductivity that extends through the thickness dimension of the insulating layer in the range of about 50 mW / mK or less, about 40 mW / mK or less, about 30 mW / mK or less, about 25 mW / mK or less, about 20 mW / mK or less, about 18 mW / mK or less, about 16 mW / mK or less, about 14 mW / mK or less, about 12 mW / mK or less, about 10 mW / mK or less, about 5 mW / mK or less, or in any two of these values ​​at 25°C. In a particular embodiment, the insulating layer disclosed herein has a thermal conductivity spanning the thickness dimension of the insulating layer within a range of about 60 mW / mK or less, about 50 mW / mK or less, about 40 mW / mK or less, about 30 mW / mK or less, about 25 mW / mK or less, about 20 mW / mK or less, about 18 mW / mK or less, about 16 mW / mK or less, about 14 mW / mK or less, about 12 mW / mK or less, about 10 mW / mK or less, about 5 mW / mK or less, or any two of these values ​​at 600°C.

[0093] Under loads up to about 5 MPa, the insulating layer of this disclosure (e.g., an insulating layer including an aerogel) can maintain its thermal conductivity (typically measured in mW / mK) unchanged or increase by an insignificant amount. In a particular embodiment, under loads up to about 5 MPa, the insulating layer of this disclosure has a thermal conductivity throughout its thickness dimension within a range of about 50 mW / mK or less, about 40 mW / mK or less, about 30 mW / mK or less, about 25 mW / mK or less, about 20 mW / mK or less, about 18 mW / mK or less, about 16 mW / mK or less, about 14 mW / mK or less, about 12 mW / mK or less, about 10 mW / mK or less, about 5 mW / mK or less, or any two of these values ​​at 25°C. The thickness of the aerogel insulating layer may be reduced due to the load borne by the aerogel insulating layer. For example, under loads ranging from approximately 0.50 MPa to 5 MPa, the thickness of the aerogel insulation layer can be reduced by 50% or less, 40% or less, 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, 5% or less, or any two of these values. While the thermal resistance of the insulation layer including the aerogel may decrease with decreasing thickness, the thermal conductivity may remain unchanged or increase by a negligible amount.

[0094] In a particular embodiment, the insulating layer disclosed herein may have a heat of combustion of about 750 cal / g or less, about 717 cal / g or less, about 700 cal / g or less, about 650 cal / g or less, about 600 cal / g or less, about 575 cal / g or less, about 550 cal / g or less, about 500 cal / g or less, about 450 cal / g or less, about 400 cal / g or less, about 350 cal / g or less, about 300 cal / g or less, about 250 cal / g or less, about 200 cal / g or less, about 150 cal / g or less, about 100 cal / g or less, about 50 cal / g or less, about 25 cal / g or less, about 10 cal / g or less, or within any two of these values. An insulating layer with an improved heat of combustion will have a lower heat of combustion value relative to the reference insulating layer compared to another insulating layer. In a particular embodiment of this disclosure, the heat of combustion (HOC) of the insulation layer is improved by incorporating fire-retardant additives into the insulation layer.

[0095] In a particular embodiment, the insulating layer disclosed herein has a thermal decomposition initiation temperature of about 300°C or higher, about 320°C or higher, about 340°C or higher, about 360°C or higher, about 380°C or higher, about 400°C or higher, about 420°C or higher, about 440°C or higher, about 460°C or higher, about 480°C or higher, about 500°C or higher, about 515°C or higher, about 550°C or higher, about 600°C or higher, or within any two of these values. In the context herein, for example, a thermal decomposition initiation temperature of a first composition that is higher than that of a second composition will be considered an improvement of the first composition relative to the second composition. It is contemplated herein that the thermal decomposition initiation temperature of a composition or material increases when one or more fire-retardant additives are added, compared to a composition that does not contain any fire-retardant additives.

[0096] The term "flexural modulus" or "flexural elastic modulus" is a measure of a material's stiffness / bending resistance when a force is applied perpendicular to the long side of the sample—known as the three-point bending test. The flexural modulus represents a material's ability to bend. It is expressed as the slope of the initial linear portion of the stress-strain curve and is calculated by dividing the stress change by the corresponding strain change. Therefore, the stress-to-strain ratio is a measure of the flexural modulus. The international standard unit for flexural modulus is Pascal (Pa or N / m² or m⁻¹·kg⁻²). The practical unit used is megapascal (MPa or N / mm²) or gigapascal (GPa or kN / mm²). In the U.S. commonly used unit, it is expressed in pounds (forces) per square inch (psi). In specific embodiments, the insulation layer disclosed herein has a flexural modulus of approximately 8 MPa or less, approximately 7 MPa or less, approximately 6 MPa or less, approximately 5 MPa or less, approximately 4 MPa or less, or approximately 3 MPa or less. Preferably, the insulating layer (e.g., aerogel) disclosed herein has a flexural modulus of about 2 MPa to about 8 MPa.

[0097] As described above, the compressibility and elasticity properties of the materials between the battery or battery module and battery pack are important to accommodate the expansion of the battery during its lifespan. In a particular embodiment, the insulating layer or the multilayer material including the insulating layer (i) is compressible to at least 50%, preferably at least 65%, most preferably at least 80% of its initial or uncompressed thickness, and (ii) has sufficient elasticity to recover to at least 70%, preferably at least 75%, most preferably at least 80% of its initial or uncompressed thickness after a few seconds of compression.

[0098] In a particular embodiment, the compressibility modulus of the insulating layer (e.g., a layer including aerogel), the compressible component of the multilayer material including the insulating layer, or the entire multilayer material is about 1 MPa, about 2 MPa, about 3 MPa, about 4 MPa, about 5 MPa, about 6 MPa, about 7 MPa, about 8 MPa, about 9 MPa, about 10 MPa, about 11 MPa, about 12 MPa, or in any two of these values.

[0098] Aerogel

[0099] The aerogel of the present invention may be organic, inorganic, or a mixture thereof. In some embodiments, the aerogel comprises a silicon dioxide-based aerogel. The insulating layer of the multilayer material comprising the aerogel further comprises a reinforcing material. The reinforcing material may be any material that provides elasticity, consistency, or structural stability to the aerogel material. Examples of well-known reinforcing materials include, but are not limited to, open-cell macroporous framework reinforcing materials, closed-cell macroporous framework reinforcing materials, open-cell membranes, honeycomb reinforcing materials, polymeric reinforcing materials, and fiber reinforcing materials, such as discrete fibers, woven materials, nonwoven materials, needle-punched nonwoven materials, cotton wool, mesh, mats, and felt.

[0100] The reinforcing material may be selected from organic polymer-based fibers, inorganic fibers, carbon-based fibers, or combinations thereof. The inorganic fibers are selected from glass fibers, rock fibers, metal fibers, boron fibers, ceramic fibers, basalt fibers, or combinations thereof.

[0101] In some embodiments, the reinforcing material may include a reinforcing layer comprising a plurality of material layers. For example, the plurality of material layers may be bonded together. In an example embodiment, at least one of the plurality of layers may include a first material, and at least another of the plurality of layers may include a second material. The first material and the second material may have the same or different material properties. For example, the first material may be more compressible than the second material. As another example, the first material may include a closed battery, and the second material may include an open battery.

[0102] Aerogels are described as frameworks for interconnected structures, typically composed of interconnected oligomers, polymers, or colloidal particles. Aerogel frameworks can be made from a range of precursor materials, including inorganic precursor materials (e.g., precursors for manufacturing silica-based aerogels); organic precursor materials (precursors for manufacturing carbon-based aerogels); mixed inorganic / organic precursor materials; and combinations thereof. In the context of this disclosure, the term "amalgam aerogel" refers to an aerogel made from a combination of two or more different gel precursors; the corresponding precursors are referred to as "mixed precursors."

[0102] Inorganic Aerogel

[0103] Inorganic aerogels are typically formed from metal oxides or metal alkoxides. These metal oxides or alkoxides can be based on oxides or alkoxides of any metal capable of forming oxides. Such metals include, but are not limited to, silicon, aluminum, titanium, zirconium, hafnium, yttrium, vanadium, and cerium. Inorganic silica aerogels are traditionally produced through the hydrolysis and condensation of silica alkoxides (e.g., tetraethoxysilane) or through gelation using silicic acid or water glass. Other related inorganic precursor materials for the synthesis of silica-based aerogels include, but are not limited to, metal silicates, such as sodium silicate or potassium silicate, alkoxysilanes, partially hydrolyzed alkoxysilanes, tetraethoxysilanes (TEOS), partially hydrolyzed TEOS, condensation polymers of TEOS, tetramethoxysilanes (TMOS), partially hydrolyzed TMOS, condensation polymers of TMOS, tetrapropoxysilanes, partially hydrolyzed and / or condensation polymers of tetrapropoxysilanes, polyethyl silicate, partially hydrolyzed polyethyl silicate, monomeric alkylalkoxysilanes, bis(trialkoxyalkyl) or aryl silanes, polyhedral silsesquioxanes, or combinations thereof.

[0104] In specific embodiments of this disclosure, pre-hydrolyzed TEOS (e.g., Silbond H-5 (SBH5, Silbond Corporation), hydrolyzed at a water / silica ratio of approximately 1.9-2) may be commercially available, or may be further hydrolyzed prior to inclusion in the gelation process. Partially hydrolyzed TWOS or TMOS (e.g., polyethylene silicate (Silbond 40) or polymethyl silicate) may also be commercially available, or may be further hydrolyzed prior to inclusion in the gelation process.

[0105] Inorganic aerogels may also include gel precursors comprising at least one hydrophobic group, such as alkyl metal alkoxides, cycloalkyl metal alkoxides, and aryl metal alkoxides, which can impart or improve specific properties in the gel, such as stability and hydrophobicity. Inorganic silica aerogels may specifically include hydrophobic precursors, such as alkyl silanes or aryl silanes. Hydrophobic gel precursors can be used as primary precursor materials to form the framework of the gel material. However, hydrophobic gel precursors are more often used as co-precursors to bind simple metal alkoxides during the formation of hybrid aerogels. Hydrophobic inorganic precursor materials used in the synthesis of silica-based aerogels include, but are not limited to, trimethylmethoxysilane (TMS), dimethyldimethoxysilane (DMS), methyltrimethoxysilane (MTMS), trimethylethoxysilane, dimethyldiethoxysilane (DMDS), methyltriethoxysilane (MTES), ethyltriethoxysilane (ETES), diethyldiethoxysilane, dimethyldiethoxysilane (DMDES), ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane (PhTES), hexamethyldisilazane, and hexaethyldisilazane. Any derivative of any of the above precursors can be used, and specifically, other chemical groups for specific polymerization can be added to or crosslinked to one or more of the above precursors.

[0106] Aerogels can also be treated to impart or improve hydrophobicity. Hydrophobic treatments can be applied to sol-gel solutions, wet gels prior to liquid extraction, or aerogels after liquid extraction. Hydrophobic treatments are particularly common in the manufacture of metal oxide aerogels (e.g., silica aerogels). Examples of hydrophobic treatments of gels are discussed in more detail below, particularly in the context of treating silica wet gels. However, the specific examples and illustrations provided herein are not intended to limit the scope of this disclosure to any particular type of hydrophobic treatment step or aerogel matrix. This disclosure may include any gel or aerogel known to those skilled in the art, and related methods for hydrophobic treatment of aerogels (in wet or dry aerogel form).

[0107] Hydrophobic treatment is performed by reacting the hydroxyl groups on the gel (e.g., silanol groups (Si-OH) present on the framework of a silica gel) with the functional groups of a hydrophobic agent. The resulting reaction transforms the silanol groups and the hydrophobic agent into hydrophobic groups on the framework of the silica gel. The hydrophobic agent compound can react with the hydroxyl groups on the gel according to the following reaction: RNMX4-N (hydrophobic agent) + MOH (silanol) → MOMRN (hydrophobic group) + HX. Hydrophobic treatment can occur on the macroscopic surface outside the silica gel or on the pore surface within the porous network of the gel.

[0108] The gel can be immersed in a mixture of a hydrophobic agent and an optional hydrophobic treatment solvent (in which the hydrophobic agent is soluble and miscible with the gel solvent in the wet gel). A wide range of hydrophobic treatment solvents can be used, including solvents such as methanol, ethanol, isopropanol, xylene, toluene, benzene, dimethylformamide, and hexane. The hydrophobic agent, in liquid or gaseous form, can also be directly contacted with the gel to impart hydrophobicity.

[0109] The hydrophobic treatment process may include mixing or stirring to help the hydrophobic agent penetrate the wet gel. The hydrophobic treatment process may also include changing other conditions, such as temperature and pH, to further enhance and optimize the treatment reaction. After the reaction is complete, the wet gel is washed to remove unreacted compounds and reaction byproducts.

[0110] Hydrophobic agents used for hydrophobic treatment of aerogels are generally compounds having the molecular formula RNMX4-N; wherein, M is a metal; R is a hydrophobic group, such as CH3, CH2CH3, C6H6, or similar hydrophobic alkyl, cycloalkyl, or aryl moiety; and X is a halogen, usually Cl. Specific examples of hydrophobic agents include, but are not limited to, trimethylchlorosilane (TMCS), triethylchlorosilane (TECS), triphenylchlorosilane (TPCS), dimethylchlorosilane (DMCS), and dimethyldichlorosilane (DMDCS). Hydrophobic agents may also have the molecular formula Y(R3M)2; wherein, M is a metal; Y is a bridging group, such as NH or O; and R is a hydrophobic group, such as CH3, CH2CH3, C6H6, or similar hydrophobic alkyl, cycloalkyl, or aryl moiety. Specific examples of such hydrophobic agents include, but are not limited to, hexamethyldisilazane [HMDZ] and hexamethyldisilazane [HMDSO]. Hydrophobic agents may further include compounds having the molecular formula RNMV4-N, wherein the V group is a reactive or leaving group other than a halogen. Specific examples of such hydrophobic agents include, but are not limited to, vinyltriethoxysilane and vinyltrimethoxysilane.

[0111] The hydrophobic treatment disclosed herein can also be performed during the removal, displacement, or drying of the liquid in the gel. In certain embodiments, the hydrophobic treatment can be performed in a supercritical fluid environment (e.g., but not limited to supercritical carbon dioxide) and can be combined with drying or extraction steps.

[0111] Organic Aerogel

[0112] Organic aerogels are typically formed from carbon-based polymeric precursors. Such polymeric materials include, but are not limited to, resorcinol-formaldehyde (RF), polyimide, polyacrylate, polymethyl methacrylate, acrylate oligomers, polyoxyethylene, polyurethane, polyphenols, polybutadiene, trialalkoxysilane-terminated polydimethylsiloxane, polystyrene, polyacrylonitrile, polyfurfural, melamine-formaldehyde, cresol-formaldehyde, phenol-furfural, polyethers, polyols, polyisocyanates, polyhydroxybenzene, polyvinyl alcohol dialdehyde, polycyanurate, polyacrylamide, various epoxy resins, agar, agarose, chitosan, and combinations thereof. For example, organic RF aerogels are typically prepared by sol-gel polymerization of resorcinol or melamine with formaldehyde under alkaline conditions.

[0112] Organic / Inorganic Mixed Aerogel

[0113] Organic / inorganic hybrid aerogels are mainly composed of organically modified silica (ormosil) aerogels. These organically modified silica materials include organic components covalently bonded to the silica network. Organically modified silica is typically formed using the conventional alkoxide precursor Y(OX)4 through the hydrolysis and condensation of organically modified silane R--Si(OX)3. In these formulas, X can represent, for example, CH3, C2H5, C3H7, C4H9; Y can represent, for example, Si, Ti, Zr, or Al; R can be any organic fragment, such as methyl, ethyl, propyl, butyl, isopropyl, methacrylate, acrylate, vinyl, epoxide, etc. The organic components in the organically modified silica aerogel can also be dispersed throughout the silica network or chemically bonded to the silica network.

[0114] In specific embodiments, the aerogel disclosed herein is an inorganic silica aerogel mainly formed from a prepolymerized silica precursor (preferably an oligomer), or a hydrolyzed silicate formed from a silica salt in an alcohol solvent. In specific embodiments, such prepolymerized silica precursors or hydrolyzed silicates may be formed in situ from other precursors or silicates (e.g., alkoxysilanes or water glass). However, the present invention can be implemented using any other aerogel compositions known to those skilled in the art, and is not limited to any single precursor material or mixture of precursor materials.

[0114] Large hole

[0115] As described above, the aerogel composition according to embodiments of the present disclosure may include an aerogel framework comprising macropores. Without being bound by any particular operational theory, the presence of macropores within the aerogel framework allows for the compression of the aerogel composition (e.g., enhancing the aerogel composition) while maintaining or even improving thermal properties, such as reducing thermal conductivity. For example, the macropores may be deformed, compressed, or otherwise reduced in size by compression of the composition, thereby reducing the thickness of the composition under load. However, as the macropores deform, they effectively become smaller pores. Therefore, when the macropores deform, the heat transfer path within the aerogel framework can become more tortuous, thereby improving thermal properties, such as reducing thermal conductivity. In the context of this disclosure, "mesopore" refers to a pore with an average pore diameter in the range of about 2 nm to about 50 nm. Aerogel frameworks are typically mesopores (i.e., primarily comprising pores with an average diameter from about 2 nm to about 50 nm). In certain embodiments, the aerogel framework of the aerogel composition of the present disclosure may include macropores. In the context of this disclosure, "macropore" refers to a pore with an average pore size greater than about 50 nm. Aerogel frameworks may include macropores and mesopores. For example, at least 10% of the pore volume of the aerogel framework may be composed of macropores, at least 5% of the pore volume of the aerogel framework may be composed of macropores, at least 75% of the pore volume of the aerogel framework may be composed of macropores, at least 95% of the pore volume of the aerogel framework may be composed of macropores, or at least 100% of the pore volume of the aerogel framework may be composed of macropores. In some specific embodiments, the aerogel framework may be a macroporous aerogel framework, such that the majority of its pore volume is composed of macropores. In some cases, the macroporous aerogel framework may also include micropores and / or mesopores. In some embodiments, the average pore size (diameter) of the pores in the aerogel framework may be greater than 50 nm, greater than 50 nm to 5000 nm, 250 nm to 2000 nm, 500 nm to 2000 nm, 500 nm to 1400 nm, or 1200 nm. In specific embodiments, the average pore size (diameter) may be greater than 50 nm, greater than 50 nm to 1000 nm, preferably 100 nm to 800 nm, and more preferably 250 nm to 750 nm.

[0116] Uniform and non-uniform pore size distribution

[0117] In some embodiments, the pore size variation within the aerogel framework may be uniformly distributed along the aerogel framework. For example, the average pore size may be substantially the same throughout the aerogel framework.

[0118] In other embodiments, the pore size variation within the aerogel frame may be non-uniformly distributed along the aerogel frame. For example, the average pore size may differ in specific regions of the aerogel frame. In some example embodiments, the average pore size may be larger in regions of the upper surface, lower surface, or both surfaces of the aerogel frame. For example, macropores may be distributed within the composition such that the ratio of macropores to mesopores is greater on the upper surface than on the lower surface, greater on the lower surface than on the upper surface, or greater on both surfaces than in the intermediate region between the upper and lower surfaces. As another example, macropores may be distributed within the composition such that the ratio of macropores to mesopores is greater near the upper surface than near the lower surface, greater near the lower surface than near the upper surface, or greater near both surfaces than in the intermediate region between the upper and lower surfaces. In other embodiments, the average pore size may be larger in the intermediate region between the upper and lower surfaces of the aerogel frame.

[0118] Macropore formation

[0119] Macropores may be formed during the manufacture of the aerogel composition. For example, macropore formation may be induced in the gel precursor material during the conversion to a gel composition. In some embodiments, macropore formation may be achieved by inducing, for example, spinodal decomposition of the gel precursor solution. Alternatively, macropore formation may be induced by adding one or more foaming agents.

[0120] Compared to mesopores and / or micropores, macropores can be formed in the resulting aerogel framework by selecting process conditions that are conducive to the formation of macropores. The number of macropores can be adjusted by implementing any one, any combination of, or all of the following variables: (1) polymerization solvent; (2) polymerization temperature; (3) polymer molecular weight; (4) molecular weight distribution; (5) copolymer composition; (6) number of branches; (7) number of crosslinks; (8) branching method; (9) crosslinking method; (10) method used to form gel; (11) type of catalyst used to form gel; (12) chemical composition of catalyst used to form gel; (13) amount of catalyst used to form gel; (14) gel forming temperature; (15) type of gas flowing through the material during gel formation; (16) gas flow rate through the material during gel formation; (17) atmospheric pressure during gel formation; (18) removal of dissolved gases during gel formation; (19) solid additives present in the resin during gel formation; (20) time of gel formation process; (21) matrix used for gel formation; (22) type of one or more solvents used in each step of the solvent replacement process; (23) solvent (24) The composition of one or more solvents used in each step of the solvent replacement process; (25) The amount of time used in each step of the solvent replacement process; (26) The residence time of the component in each step of the solvent replacement process; (27) The flow rate of the solvent used for solvent replacement; (28) The flow type of the solvent used for solvent replacement; (29) The stirring rate of the solvent used for solvent replacement; (30) The temperature used in each step of the solvent replacement process; (31) The ratio of the volume of the solvent used for solvent replacement to the volume of the component; (32) The drying method; (33) The temperature of each step in the drying process; (34) The pressure of each step in the drying process; (35) The composition of the gas used in each step of the drying process; (36) The gas flow rate during each step of the drying process; (37) The temperature of the gas during each step of the drying process; (38) The presence of a shell surrounding the component during each step of the drying process; (39) The type of shell surrounding the component during drying; and / or (40) The solvent used in each step of the drying process. Multifunctional amines and diamine compounds can be added as solids (pure or dissolved in a suitable solvent) individually or together in one or more portions. In other cases, a method of manufacturing an aerogel may include the steps of: (a) providing a multifunctional amine compound and at least one diamine compound to a solvent to form a solution; (b) providing at least one dianhydride compound to the solution of step (a) under conditions sufficient to form a branched polymer matrix solution, wherein the branched polymer matrix is ​​dissolved in the solution; and (c) placing the branched polymer matrix solution under conditions sufficient to form an aerogel with an open-pore structure. Macropores appearing in the resulting aerogel framework can be formed in the manner described above.In a preferred and non-limiting state, the mesopores and micropores are relatively small, and the formation of macropores can be mainly controlled by controlling polymer / solvent kinetics during gel formation.

[0121] As described above, the aerogel composition according to embodiments of the present disclosure may include an aerogel framework and a reinforcing material, wherein at least a portion of the reinforcing material does not contain aerogel. For example, the aerogel framework may extend partially through the thickness of the reinforcing material. In such embodiments, portions of the reinforcing material (e.g., OCMF, fibers, or combinations thereof) may include aerogel material, and portions may not have aerogel. For example, in some embodiments, the aerogel extends through about 90% of the thickness of the reinforcing material, through about 50% to about 90% of the thickness of the reinforcing material, through about 10% to about 50% of the thickness of the reinforcing material, or through about 10% of the thickness of the reinforcing material.

[0122] Unbound from any particular operational theory, the aerogel composition (wherein at least a portion of the reinforcing material does not contain aerogel) can provide good compressibility, compressive elasticity, and compliance properties. For example, the properties of the reinforcing material can be selected to provide sufficient reinforcement and support for thermal properties in regions containing aerogel, and sufficient compressibility, compressive elasticity, and / or compliance in regions without aerogel. The aerogel-containing portion of the reinforced aerogel composition can provide the desired thermal conductivity, for example, less than about 25 mW / m*K, while the reinforcing portion without aerogel can provide or improve the desired physical properties, such as compressibility.

[0123] In some embodiments, a reinforced aerogel composition (where at least a portion of the reinforcing material does not contain aerogel) can be formed using the methods disclosed herein, wherein the reinforcing material is combined with an amount sufficient to partially fill the reinforcing material with the precursor solution. For example, the volume of the precursor may be smaller than the volume of the reinforcing material, such that the precursor extends only partially through the reinforcing material. Upon drying, the resulting reinforced aerogel composition will comprise an aerogel framework extending to less than the full thickness of the reinforcing material, as described above. In other embodiments, a reinforced aerogel composition (where at least a portion of the reinforcing material does not contain aerogel) can be formed by removing a surface aerogel layer from the aerogel composition.

[0124] In some embodiments, the reinforced aerogel composition (where at least a portion of the reinforcing material does not contain aerogel) may be formed using a reinforcing material having mixed characteristics along the thickness of the reinforcing material. For example, the reinforcing material may comprise multiple layers, each with different properties, such as differences in average pore size, material composition, closed-cell, open-cell, surface treatment, or combinations thereof. The multiple layers may be bonded to each other, for example using adhesives, flame bonding, or other suitable methods or mechanisms (such as those discussed herein). The different properties of the reinforcing material may provide different aerogel distributions in the layers. For example, the open-cell portions of the reinforcing material may comprise an aerogel framework, while the closed-cell portions remain substantially aerogel-free. Similarly, other material properties of the reinforcing material or its layers may determine the aerogel distribution within the reinforcing material and thus within the reinforced aerogel composition.

[0125] In some example embodiments, a reinforced aerogel composition (where at least a portion of the reinforcing material does not contain aerogel) can be formed using the methods disclosed herein, wherein the characteristics of the reinforcing material or layer control or influence the amount of precursor solution filling the material or layer (e.g., during a casting process) to provide partial filling of the reinforcing material with the precursor solution. For example, one layer of the reinforcing material may have open pores, and another layer of the reinforcing material may have closed pores. When the precursor solution is combined with such a reinforcing material, the gel precursor solution can penetrate into the open pores of the layer without significantly penetrating into the closed pores of the other layer. When such a composition is dried, the resulting reinforced aerogel composition may include portions that do not contain aerogel (e.g., the closed-pore layer), while another portion (e.g., the open-pore layer) contains aerogel.

[0126] In some embodiments, the additives disclosed herein (e.g., heat-absorbing additives, light-shielding additives, fire-retardant additives, or other additives) may be unevenly dispersed in the reinforced aerogel composition. For example, the additive material may vary with the thickness of the aerogel composition or along its length and / or width. For example, the additive may accumulate on one side of the aerogel composition. In some embodiments, the one or more additive materials may be concentrated in one layer of the aerogel composition or provided as a separate layer consisting essentially of additives adjacent to or attached to the composition. For example, the thermal control may include a layer consisting essentially of a heat-absorbing material (e.g., gypsum, sodium bicarbonate, magnesium oxide-based cement). In other example embodiments, the aerogel composition may also include at least one additional material layer located within the composition or as a cover layer. For example, the layer may be a layer selected from the group consisting of polymer flakes, metal flakes, fiber flakes, highly oriented graphite materials (e.g., pyrolytic graphite flakes), and fabric flakes. In some embodiments, the overlay may be attached to the composition, for example, by an adhesive mechanism selected from the group consisting of aerosol adhesives, urethane adhesives, acrylate adhesives, hot melt adhesives, epoxy resins, rubber resin adhesives, polyurethane composite adhesives, and combinations thereof. In some embodiments, the overlay may be attached to the composition by a non-adhesive mechanism (e.g., a mechanism selected from the group consisting of flame bonding, needle punching, sewing, sealing bags, rivets, buttons, clips, wrapping, supports, and combinations thereof). In some embodiments, any combination of the above-described adhesive and non-adhesive mechanisms may be used to attach the overlay to the composition.

[0126] Powdered Aerogel Composition

[0127] As described herein, aerogel compositions or composites may include materials for incorporating aerogel microparticles, particles, granules, microbeads, or powders into solid or semi-solid materials, such as in combination with binders, such as adhesives, resins, cements, foams, polymers, or similar solid or cured materials. For example, an aerogel composition may include reinforcing materials, aerogel particles, and optionally binders. In exemplary embodiments, a slurry comprising aerogel particles and at least one wetting agent may be provided. For example, the aerogel particles may be coated or wetted with at least one wetting agent (e.g., a surfactant or dispersant). The aerogel particles may be completely wetted, partially wetted (e.g., surface-wetted), or present in the slurry. Preferably, the wetting agent is volatile to allow proper restoration of the hydrophobicity of the hydrophobic aerogel particles. If the wetting agent remains on the surface of the aerogel particles, the residual wetting agent may promote the overall thermal conductivity of the composite material. Therefore, a preferred wetting agent is a removable wetting agent, for example, through evaporation, with or without decomposition or other means. Generally, any wetting agent compatible with the aerogel can be used.

[0127] Wetting agent

[0128] A slurry or aerogel coated with a wetting agent can serve as a method for readily incorporating hydrophobic aerogels into a variety of materials, such as other aqueous fluids, slurries, adhesives, and bonding agents, which can selectively harden to form solid materials, fibers, metallized fibers, discrete fibers, woven materials, nonwoven materials, needle-punched nonwoven materials, wadding, nets, mats, felts, and combinations thereof. An aerogel wetted with at least one wetting agent or a slurry containing an aerogel and at least one wetting agent facilitates the incorporation and uniform distribution of the hydrophobic aerogel. Wet fabrication processes (e.g., those described in U.S. Patent Nos. 9,399,864, 8,021,583, 7,635,411, and 5,399,422, which are incorporated herein by reference in their entirety) use aqueous slurries to disperse aerogel particles, fibers, and other additives. The slurry can then be dehydrated to form a layer consisting of aerogel particles, fibers, and additives, which can be dried and selectively calendered to produce an aerogel complex.

[0128] Aerogel particles and additives

[0129] In other embodiments, the aerogel composition may include aerogel particles, at least one inorganic matrix material, and optionally fibers, auxiliary materials, additives, and other inorganic binders. In some embodiments, the inorganic matrix material may include layered silicates, such as naturally occurring layered silicates like kaolin, clay, or bentonite, synthetic layered silicates like magadiite or kenyaite, or mixtures of these materials. The layered silicate may be calcined or uncalcined, for example, by drying the material and removing water of crystallization. In some embodiments, the inorganic matrix material may also include inorganic binders, such as cement, lime, gypsum, or suitable mixtures thereof, to bind the layered silicate. In some embodiments, the inorganic matrix material may also include other inorganic additives disclosed herein, such as fire-retardant additives, opacifiers, or combinations thereof. U.S. Patent Nos. 6,143,400 and 6,083,619 disclose exemplary processes and aerogel compositions comprising inorganic matrix materials (incorporated herein by reference in their entirety). In some embodiments, the aerogel composition may comprise aerogel particles coated on or absorbed therein of woven materials, nonwoven materials, needle-punched nonwoven materials, wadding, netting, matting, felt, and combinations thereof. The composition may include an adhesive. It may also include additives as disclosed herein, such as flame-retardant additives, light-blocking agents, or combinations thereof. U.S. Patent No. 2019 / 0264381A1 discloses exemplary processes and aerogel compositions coated on or absorbed therein of fabrics (incorporated herein by reference in their entirety).

[0130] As described herein, aerogel composites can be laminated or coated with other materials, such as a coating material reinforcement layer. In one embodiment, this disclosure provides a multilayer laminated material comprising: at least one base layer including a reinforcing aerogel composition, and at least one coating layer. In one embodiment, the coating layer includes a reinforcing material. In one embodiment, the reinforcing aerogel composition is reinforced with a fiber reinforcement layer or an open-cell foam reinforcement layer. In one embodiment, this disclosure provides a multilayer laminated material comprising: a base layer including a reinforcing aerogel composition, and at least two coating layers including reinforcing materials, wherein the two coating layers are located on opposite surfaces of the base layer. For example, the multilayer aerogel laminated composite can be manufactured according to the method and materials described in U.S. Patent Application 2007 / 0173157.

[0131] The overlay layer may include materials to help provide specific properties to the final composite structure, such as increased flexibility or reduced dust. The overlay material may be rigid or flexible. The overlay material may include a conductive layer or a reflective foil. For example, the overlay material may include a metallic or metallized material. The overlay material may include a nonwoven material. The overlay layer may be disposed on the surface of the composite structure or the reinforcing aerogel composite (e.g., a thermal control) forming the composite structure. The overlay layer may form a continuous coating or pouch around the composite structure or the reinforcing aerogel composite (e.g., a thermal control) forming the composite structure. In some embodiments, the one or more overlay layers may encapsulate the composite structure or the reinforcing aerogel composite forming the composite structure.

[0132] In one embodiment, the covering layer includes a polymer sheet surrounding the composite structure; more specifically, the polymer material includes: polyester, polyethylene, polyurethane, polypropylene, polyacrylonitrile, polyamide, aramid; more specifically, the polymer includes, for example, polyethylene terephthalate, low-density polyethylene, ethylene-propylene copolymer, poly(4-methylpentane), polytetrafluoroethylene, poly(1-butene), polystyrene, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polyacrylonitrile, polymethyl methacrylate, polyoxymethylene, polyphenylene oxide, cellulose triacetate, polycarbonate, polyvinyl naphthalate, polycaprolactam, polyhexamethylene diamide, polysulfonamide, polyimide, or combinations thereof. In one embodiment, the polymer sheet comprises or is substantially composed of a foamed polymer material; more specifically, it comprises foamed polymer materials such as PTFE (ePTFE), expanded polypropylene (ePP), expanded polyethylene (ePE), expanded polystyrene (ePS), or combinations thereof. In a preferred embodiment, the covering material is substantially composed of a foamed polymer material. In one embodiment, the polymer sheet comprises or is substantially composed of a microporous polymer material characterized by pore sizes ranging from 0.1 μm to 210 μm, 0.1 μm to 115 μm, 0.1 μm to 15 μm, or 0.1 μm to 0.6 μm.

[0133] In one embodiment, the cover material comprises or is substantially composed of a fluoropolymer material. In the context of this disclosure, the terms "fluoropolymer" or "fluoropolymer material" refer to a material primarily composed of a polyfluorocarbon compound. Suitable fluoropolymer cover materials include, but are not limited to: polytetrafluoroethylene (PTFE), including microporous PTFE as described in U.S. Patent 5,814,405, and foamed PTFE (ePTFE), such as Gore-Tex® (available from WLGore); polyvinylidene fluoride (PVF); polyvinylidene fluoride (PVDF); perfluoroalkoxy (PFA); fluorinated ethylene-propylene (FEP); polychlorotrifluoroethylene (PCTFE); ethylene tetrafluoroethylene (ETFE); polyvinylidene fluoride (PVDF); ethylene trifluorochloroethylene (ECTFE); and combinations thereof. In a preferred embodiment, the cover material is substantially composed of a fluoropolymer material. In a preferred embodiment, the covering material is substantially composed of foamed PTFE (ePTFE) material.

[0134] In one embodiment, the overlay material comprises or is substantially composed of a fluoropolymer-free material. In the context of this disclosure, the terms "fluoropolymer-free" or "fluoropolymer-free material" refer to a material that does not contain fluoropolymer materials. Suitable fluoropolymer-free overlay materials include, but are not limited to: aluminized Mylar; low-density polyethylene, such as Tyvek® (available from DuPont); rubber or rubber composites; nonwoven materials, elastic fibers, such as spadex, nylon, Lycra, or elastane; and combinations thereof. In one embodiment, the overlay material is a flexible overlay material.

[0135] In some embodiments, the overlay material may include automotive resins and polymers, such as resins and polymers with a maximum operating temperature of up to about 100°C, up to about 120°C, or up to about 150°C. For example, the overlay material may include acrylonitrile butadiene styrene (ABS), polycarbonate ABS, polypropylene, polyurethane, polystyrene, polyethylene, polycarbonate, polyimide, polyamide, PVC, or combinations thereof. For example, the aerogel composite and thermal control according to the embodiments disclosed herein may include a layer of automotive resin or automotive polymer, a metallic or metallized layer, and an aerogel layer.

[0136] An adhesive can be used to attach the overlay to a substrate, the adhesive being suitable for fixing inorganic or organic overlay materials to a substrate reinforcement. Examples of adhesives that can be used in this disclosure include, but are not limited to: cement-based adhesives, sodium silicate, latex, pressure-sensitive adhesives, silicone, polystyrene, aerosol adhesives, urethane, acrylate adhesives, hot-melt bonding systems, bonding systems sold by 3M, epoxy resins, rubber resin adhesives, and polyurethane adhesive mixtures, such as those described in U.S. Patent 4,532,316.

[0137] The overlay can also be attached to the substrate using non-adhesive materials or techniques suitable for fixing inorganic or organic overlay materials to the substrate reinforcement. Examples of non-adhesive materials or techniques that can be used in this disclosure include, but are not limited to: heat sealing, ultrasonic stitching, RF sealing, stitching or threading, needle punching, sealing bags, rivets or buttons, clips, wrapping, or other non-adhesive press-fit materials.

[0138] The topcoat can be attached to the base layer at any stage of the manufacturing process of the aerogel composite material. In one embodiment, the topcoat is attached to the base layer after the sol-gel solution is injected into the base reinforcement material but before gelation. In another embodiment, the topcoat is attached to the base layer after the sol-gel solution is injected into the base reinforcement material and subsequently gelled, but before aging or drying the gel material. In yet another embodiment, the topcoat is attached to the base layer after aging and drying the gel material. In a preferred embodiment, the topcoat is attached to the reinforcement material of the base layer before the sol-gel solution is injected into the base reinforcement material. The topcoat may be impermeable to both solids and fluids. The topcoat may be porous and permeable to fluids. In a preferred embodiment, the topcoat is porous and permeable to fluids and includes pores or holes of a sufficiently large diameter to allow fluid to diffuse through the topcoat material. In another preferred embodiment, a topcoat layer is attached to the base reinforcement material before the sol-gel solution is injected into it. The topcoat layer is porous and fluid-permeable, and contains pores or holes of a sufficiently large diameter to allow fluid to diffuse through the topcoat material. In yet another preferred embodiment, a topcoat layer is attached to an open-cell foam reinforcement material before the sol-gel solution is injected into it. The topcoat layer is porous and fluid-permeable, and contains pores or holes of a sufficiently large diameter to allow fluid to diffuse through the topcoat material.

[0138] Sunscreen

[0139] The aerogel composition may include a light-shielding agent to reduce the radiative component of heat transfer. At any point prior to gel formation, a light-shielding compound or a precursor thereof may be dispersed in a mixture including the gel precursor. Examples of light-shielding compounds include, but are not limited to, boron carbide (B4C), diatomaceous earth, manganese ferrite, MnO, NiO, SnO, Ag2O, Bi2O3, carbon black, graphite, titanium dioxide, ferrotitanium, alumina, zirconium silicate, zirconium oxide, iron oxide (I), iron oxide (III), manganese dioxide, ferrotitanium (ilmenite), chromium oxide, carbides (e.g., SiC, TiC, or WC), or mixtures thereof. Examples of light-shielding compound precursors include, but are not limited to, TiOSO4 or TiOCl2. In some embodiments, the light-shielding compound used as an additive may exclude silicon carbide whiskers or fibers. When aerogel compositions are intended for use in electrical devices, such as as a barrier layer in batteries or other related applications, compositions including light-blocking agents may desire high dielectric strength and high volumetric and surface resistivity. In such embodiments, the carbon additive used as a light-blocking agent may be non-conductive or modified to reduce conductivity. For example, the light-blocking agent may be surface-oxidized to reduce conductivity. In some embodiments, carbon-containing additives with inherent conductivity may be used as light-blocking agents in aerogel compositions (intended for use in electrical devices). In such embodiments, the conductive carbon-containing additive may be used at concentrations below the permeation threshold to provide suitable dielectric strength for the composition in electrical devices.

[0139] Fire-retardant additive

[0140] The aerogel composition may include one or more fire-retardant additives. In the context of this disclosure, the term "fire-retardant additive" refers to a material that has an endothermic effect in the context of a fire reaction and can be incorporated into the aerogel composition. Furthermore, in certain embodiments, the endothermic decomposition (ED) onset temperature of the fire-retardant additive is no more than 100°C higher than the thermal decomposition onset temperature (Td) of the aerogel composition containing the fire-retardant additive, and in certain embodiments, the ED is no more than 50°C lower than the Td of the aerogel composition containing the fire-retardant additive. In other words, the ED of the fire-retardant additive has a range from (Td-50°C) to (Td+100°C).

[0140]

[0141] Before, during, or even after incorporating or mixing with a sol (e.g., a silica sol prepared from alkyl silicates or water glass in various ways as understood in the art), the fire-retardant additive may be mixed with or otherwise dispersed in a medium including ethanol and optionally up to 10% by volume water. The mixture may be mixed and / or stirred as needed to achieve substantially uniform dispersion of the additive in the medium. Without being theoretically constrained, the use of the above-mentioned clays and other fire-retardant additives in hydrated form provides additional endothermic effects. For example, Xuyong stone clay (available from Applied Minerals under the trade name DRAGONITE, or from Imerys under the trade name Halloysite) and kaolinite clay are aluminosilicate clays whose hydrated form has an endothermic effect (gas dilution) by releasing hydrated water at high temperatures. As another example, hydrated carbonates can release carbon dioxide upon heating or at high temperatures.

[0142] In the context of this disclosure, the term "heat of dehydration" refers to the amount of heat required for the evaporation of water (and dihydroxylation, if applicable) from a material in its hydrated form without exposure to high temperatures. Heat of dehydration is usually expressed on a per-unit-weight basis.

[0143] In a specific embodiment, the fire-retardant additive disclosed herein has a thermal decomposition initiation temperature of about 100°C or higher, about 130°C or higher, about 200°C or higher, about 230°C or higher, about 240°C or higher, about 330°C or higher, 350°C or higher, about 400°C or higher, about 415°C or higher, about 425°C or higher, about 450°C or higher, about 500°C or higher, about 550°C or higher, about 600°C or higher, about 650°C or higher, about 700°C or higher, about 750°C or higher, about 800°C or higher, or within any two of these values. In a specific embodiment, the fire-retardant additive disclosed herein has a thermal decomposition initiation temperature of about 440°C or 570°C. In a particular embodiment, the fire-retardant additive disclosed herein has a thermal decomposition initiation temperature that is higher or lower than the Td of the aerogel composition (without the fire-retardant additive) containing the fire-retardant additive, which is not more than 50°C, not more than 40°C, not more than 30°C, not more than 20°C, not more than 10°C, not more than 5°C, or any two of these values.

[0144] The fire-retardant additives disclosed herein include clay materials, such as, but not limited to, layered silicate clay (e.g., illite), kaolin or kaolinite (aluminum silicate; Al2Si2O5(OH)4), metamorphic kaolin, sulphite (aluminum silicate; Al2Si2O5(OH)4), d'Andeite (aluminum silicate; Al2Si2O5(OH)4), mica (silica mineral), diaspore (aluminum hydroxide; α-AlO(OH)), gibbsite (aluminum hydroxide), boehmite (aluminum hydroxide; γ-AlO(OH)), montmorillonite, aluminum bentonite, pyrophyllite (aluminum silicate; Al2Si4O10(OH)2), natronite, phyllite, bentonite, crystal Vermiculite, palygorskite, chlorite, magnesia bentonite, green opal, chrome bentonite, diaspore, metamorphic sculptile, chloroflavonoid, halloysite, chrome aluminum quartz, bleached kaolin, terrazzo, and orthorhombic quartz, sodium bicarbonate (NaHCO3), magnesium hydroxide (or magnesium dihydroxyl, "MDH"), aluminum oxide trihydrate ("ATH"), gypsum (calcium sulfate dihydrate; CaSO4·2H2O), magnesia hydrate (MgCO3·2H2O), magnesia hydrate (MgCO3·3H2O), magnesia pentahydrate (MgCO3·5H2O), magnesite hydrate (magnesium carbonate hydrate; Mg5(CO3)4(OH)2·4H2O), and other carbonates such as, but not limited to, dolomite and lithium carbonate. In these clay materials, specific embodiments disclosed herein use clay materials having at least a partially layered structure. In specific embodiments of this disclosure, the clay material used as a fire-retardant additive in the aerogel composition contains at least some water (e.g., in a hydrated form). This additive may be in a hydrated crystalline form or may be hydrated during the manufacture / processing of the composition disclosed herein. In specific embodiments, the fire-retardant additive also includes low-melting-point additives that absorb heat without altering the chemical composition. Examples of such additives are low-melting-point glasses, such as inert glass microspheres. Other additives that can be used in the compositions disclosed herein include, but are not limited to, wollastonite (calcium silicate) and titanium dioxide (TiO2). In specific embodiments, other additives may include infrared blocking agents, such as, but not limited to, titanium dioxide or silicon carbide; vitrifying agents, such as, but not limited to, low-melting-point glass powder and calcium silicate; or charring agents, such as, but not limited to, phosphates and sulfates. In specific embodiments, special processes may need to be considered for the additive, such as techniques to ensure that the additive is uniformly distributed without significant agglomeration that could alter product performance. These process techniques may include additional static and dynamic mixers, stabilizers, adjustments to process conditions, and other techniques known in the art.

[0144] Amount of additives

[0145] The amount of additives in the aerogel compositions disclosed herein may depend on the desired properties of the composition. The amount of additives used during the preparation and processing of the sol-gel composition is generally referred to as a weight percentage relative to the silica content of the sol. The amount of additives in the sol may vary in weight percentage from about 5 wt% to about 70 wt% relative to the silica content. In certain embodiments, the amount of additives in the sol is between 10 wt% and 60 wt% relative to the silica content, and in certain preferred embodiments, it is between 20 wt% and 40 wt% relative to the silica content. In exemplary embodiments, the amount of additives in the sol is in the range of about 5% to about 20%, about 10% to about 20%, about 10% to about 30%, about 10% to about 20%, about 30 wt% to about 50 wt%, about 35 wt% to about 45 wt%, or about 35 wt% to about 40 wt% relative to the silica content. In some embodiments, the amount of additive in the sol is at least about 10 wt% of the silica content, or about 10 wt% of the silica content. In some embodiments, the amount of additive is in the range of about 5 wt% to about 15 wt% of the silica content. In certain embodiments, the additive may be of more than one type. One or more fire-retardant additives may also be present in the final aerogel composition. In some preferred embodiments including aluminum silicate fire-retardant additives, the additive is present in the aerogel composition at about 60-70 wt% of the silica content. For example, in some preferred embodiments including aluminum silicate fire-retardant additives such as kaolin or a combination of aluminum silicate fire-retardant additives such as kaolin and alumina trihydrate (“ATH”), the total amount of additive present in the aerogel composition is about 30-40 wt% of the silica content. For example, in some preferred embodiments where the additives include silicon carbide, the total amount of additives present in the aerogel composition is about 30-40 wt% relative to the silicon dioxide content, for example, 35 wt%. For example, in some preferred embodiments where the additives include silicon carbide, the total amount of additives present in the aerogel composition is about 5-15 wt% relative to the silicon dioxide content, for example, 10 wt%.

[0146] When referring to the final reinforced aerogel composition, the amount of additive is generally referred to as a weight percentage of the final reinforced aerogel composition. The amount of additive in the final reinforced aerogel composition can vary within the range of about 1% to about 50%, about 1% to about 25%, or about 10% to about 25% of the reinforced aerogel composition by weight. In an example embodiment, the amount of additive in the final reinforced aerogel composition is in the range of about 10% to about 20% of the reinforced aerogel composition by weight. In an example embodiment, the amount of additive in the final reinforced aerogel composition (as a weight percentage of the composition) is about 1%, about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 11%, about 12%, about 13%, about 14%, about 15%, about 16%, about 17%, about 18%, about 19%, about 20%, or within any of the above percentages. In a particular embodiment, the amount of additive in the final reinforced aerogel composition is about 15% by weight of the reinforced aerogel composition. In certain embodiments, the amount of additives in the final reinforcing aerogel composition is about 13% by weight of the reinforcing aerogel composition. For example, in some preferred embodiments including additives such as silicon carbide, the total amount of additives present in the aerogel composition is about 10-20%, for example, about 15% by weight of the reinforcing aerogel composition. As another example, in some preferred embodiments where the additives include silicon carbide, the total amount of additives present in the aerogel composition is about 3-5%, for example, about 4% by weight of the reinforcing aerogel composition.

[0146] Thermal decomposition initiation temperature of fire-retardant additives

[0147] In certain embodiments, fire-retardant additives may be classified or grouped based on their thermal decomposition initiation temperature. For example, fire-retardant additives may be classified or grouped as additives having a thermal decomposition initiation temperature below about 200°C, below about 400°C, or above about 400°C. For example, additives having a thermal decomposition initiation temperature below about 200°C include sodium bicarbonate (NaHCO3), magnesia trihydrate (MgCO3·3H2O), and gypsum (calcium sulfate dihydrate; CaSO4·2H2O). As another example, additives having a thermal decomposition initiation temperature below about 400°C include alumina trihydrate (“ATH”), magnesite (hydrated magnesium carbonate; Mg5(CO3)4(OH)2·4H2O), and magnesium hydroxide (or magnesium dihydroxyl, “MDH”). For example, additives with a thermal decomposition initiation temperature below about 400°C include pyrite (aluminum silicate; Al2Si2O5(OH)4), kaolin or kaolinite (aluminum silicate; Al2Si2O5(OH)4), boehmite (aluminum hydroxide; γ-AlO(OH)) or high-temperature phase change material (PCM).

[0148] In specific embodiments of this disclosure, the clay material (e.g., aluminosilicate clay, such as pyrite or kaolinite) used as an additive in the aerogel composition is in a dehydrated form, such as metapyrite or metakaolinite. Other additives that can be used in the compositions of this disclosure include, but are not limited to, wollastonite (calcium silicate) and titanium dioxide (TiO2). In specific embodiments, other additives may include infrared shading agents, such as, but not limited to, titanium dioxide or silicon carbide; vitrifying agents, such as, but not limited to, low-melting-point glass powder and calcium silicate; or charring agents, such as, but not limited to, phosphates and sulfates. In specific embodiments, additives may require special processes, such as techniques to ensure that the additive is uniformly distributed without severe agglomeration that could alter product performance. Such process techniques may include additional static and dynamic mixers, stabilizers, adjustments to process conditions, and other techniques known in the art. One or more fire-retardant additives may also be present in the final aerogel composition.

[0149] In certain embodiments, the inclusion of additives (e.g., aluminosilicate clay-based materials, such as zeolite or kaolinite) in the aerogel materials and compositions disclosed herein can provide improved high-temperature shrinkage properties. An example test method for high-temperature shrinkage is the "Standard Test Method for Linear Shrinkage of Preformed High-Temperature Thermal Insulation Subjected to Soaking Heat" (ASTM C356, ASTM International, West Conshohocken, PA). In this type of test (referred to as "hot soaking"), the material is exposed to temperatures above 1000°C for up to 60 minutes. In specific example embodiments, the aerogel material or composition disclosed herein may have high-temperature shrinkage of about 20% or less, about 15% or less, about 10% or less, about 6% or less, about 5% or less, 4% or less, 3% or less, 2% or less, 1% or less, or within any two of these values, i.e., any combination of linear shrinkage, width shrinkage, thickness shrinkage, or dimensional shrinkage.

[0150] In some example embodiments, a specific base catalyst used to catalyze the precursor reaction can generate trace amounts of alkali metals in the aerogel composition. Trace amounts (e.g., 100 to 500 ppm) of base (e.g., sodium or potassium) in the aerogel material can have detrimental effects on high-temperature shrinkage and heat durability. However, without being bound by any particular mechanism or theory, aluminosilicate clay-based materials (e.g., pyrite or kaolin) can isolate unstable bases, such as sodium or potassium, thereby reducing or eliminating the effects of bases on shrinkage and heat durability. In specific embodiments of this disclosure, the aluminosilicate clay material is in a dehydrated form, such as pyrite or kaolin. For example, the amount of pyrite or kaolin included in an aerogel material or composition with a silica content greater than about 0.5 wt% can significantly reduce heat shrinkage and heat durability. In the example embodiments, the amount of metakaolin or metasomatic stone that may be included in the aerogel material or composition is in the range of about 0.5 wt% to about 3.0 wt% relative to the silica content.

[0150] Encapsulation layer or encapsulation material layer

[0151] In some embodiments, the core portion of the multilayer material disclosed herein, or the multilayer material itself, may be encapsulated by an encapsulation layer. For example, the encapsulation layer may include one or more material layers surrounding the multilayer material and / or a material coating surrounding the multilayer material and / or the core portion of the multilayer material. For example, the encapsulation layer may include a film, layer, membrane, or coating. The encapsulation may be made of any material suitable for enclosing the composite structure or forming a reinforced aerogel composite of the composite structure. For example, the encapsulation may reduce or eliminate the generation of dust or particulate material detached from the composite structure. The encapsulation material layer may be selected from polymers, elastomers, or combinations thereof. Examples of suitable polymers include polyethylene terephthalate (PET), polyethylene (PE), polyimide (PI), rubber, and nylon, which have extremely low thermal conductivity (less than 1 W / m), thereby having the effect of reducing the thermal conductivity of the entire system across the plane. In one embodiment, the encapsulation layer includes a polyethylene terephthalate layer.

[0152] The encapsulation layer may include at least one vent allowing air to flow in and out of the panel. The encapsulation may include at least one filter for filtering particulate matter. In one example embodiment, the encapsulation layer includes: a vent allowing air to flow in and out of the panel; and a particulate filter located above the vent to retain particulate matter within the encapsulation. In another embodiment, the encapsulation layer includes an edge seal including at least one vent and at least one particulate filter. In another embodiment, the encapsulation layer includes an edge seal including at least one vent and at least one particulate filter, wherein the vent located in the edge seal allows air to flow in and out of the edge of the encapsulation, and wherein the filter captures and retains particulate matter in the flowing air to prevent air outside the encapsulation layer from being contaminated by particulate matter.

[0152] Heat capacity layer

[0153] In an exemplary embodiment, the multilayer material may include a material or material layer (i.e., a heat-capacity material) providing heat capacity, such as a material having a specific heat capacity of at least about 0.2 J / (gC). In some embodiments, the heat-capacity material providing heat capacity has a specific heat capacity of at least about 0.5 J / (gC). For example, the heat-capacity material providing heat capacity may include metals, such as aluminum, titanium, nickel, steel, iron, or combinations thereof. In some embodiments, the multilayer material may include a layer or coating of the heat-capacity material providing heat capacity. In some embodiments, the multilayer material may include particles of the heat-capacity material provided within a layer of the multilayer material, for example, within a layer of the aerogel composition. In a particular embodiment, the multilayer material may include at least one material layer providing heat capacity disposed adjacent to the aerogel composition. In a particular embodiment, the multilayer material may include at least one material layer providing heat capacity disposed between at least two of a plurality of layers of the aerogel composition. In an example embodiment, the multilayer material may include a material that is both thermally conductive and has high thermal capacity.

[0154] For example, the multilayer material may include materials that provide both heat capacity and thermal conductivity, such as metals like aluminum, titanium, nickel, steel, iron, or combinations thereof. As another example, the multilayer material may include one or more different materials or material layers that respectively provide heat capacity, thermal conductivity, or combinations thereof; for example, one layer may include a metal and another layer may include a thermally conductive polymer. Preferably, the thermally conductive layer has a melting temperature of at least 300°C, more preferably at least 600°C, more preferably at least 1000°C, and even more preferably at least 1500°C.

[0155] In some embodiments, the heat capacity material may be a self-phase change material. It is understood that for a phase change material to be suitable for widespread use in energy storage systems, the material should not only have a high heat capacity during the phase change, but also be low-cost and self-constrained, i.e., requiring no sealing or special constraints within the device's operating temperature range, such as for encapsulating battery modules. Additional desired characteristics for energy storage applications include high thermal conductivity for rapidly removing heat from heat-generating components and the ability to customize the temperature at which the phase change occurs.

[0156] In some embodiments, the heat-capacity material has a thermal conductivity of at least about 200 mW / mK along its in-plane dimension.

[0156] Heat-conducting layer

[0157] It has been found that the thermally conductive layer disclosed herein exhibits a significantly enhanced ability to rapidly dissipate heat across the entire xy plane of the multilayer material, further improving durability under high thermal loads. Examples of high thermal conductivity materials include carbon fiber, graphite, silicon carbide, metals (including but not limited to copper, stainless steel, aluminum, etc.), and combinations thereof.

[0158] In an example embodiment, the multilayer material may include a thermally conductive material or a layer of material that provides thermal conductivity. The thermally conductive layer disclosed herein helps to displace heat from localized heat loads within the battery module or battery pack. For example, the thermally conductive layer may have an in-plane thermal conductivity of at least about 200 mW / mK. The thermally conductive material may include at least one layer of a metal, carbon, a thermally conductive polymer, or a combination thereof.

[0159] In some embodiments of the above-described embodiments, the multilayer material may include one or more thermally conductive layers, i.e., having a thermal conductivity greater than 50 W / mK, preferably greater than 100 W / mK, and more preferably greater than 200 W / mK (all measured at 25°C). For example, the multilayer material may include at least one layer of a thermally conductive material, such as a layer comprising a metal, carbon, a thermally conductive polymer, or a combination thereof. In the context of these embodiments, the thermally conductive material refers to a material with a thermal conductivity greater than that of an insulating material (e.g., an aerogel composition). In a particular embodiment, the thermally conductive material has a thermal conductivity at least about one order of magnitude greater than that of the aerogel composition. In some embodiments, the multilayer material may include multiple layers of the aerogel composition. In a particular embodiment, the multilayer material may include at least one thermally conductive material layer disposed adjacent to the aerogel composition. In a particular embodiment, the multilayer material may include at least one thermally conductive material layer disposed between at least two of the multiple layers of the aerogel composition. In some embodiments, the multilayer material may include particles of the thermally conductive material disposed within the layers of the multilayer material, for example, within the layers of the aerogel composition.

[0160] To aid in heat dissipation and removal, in at least one embodiment, the thermally conductive layer is coupled to a heat sink. It should be understood that various types and configurations of heat sinks exist, as well as different techniques for coupling the heat sink and the thermally conductive layer, and this disclosure is not limited to the use of any single heat sink / coupling technique. For example, at least one thermally conductive layer of the multilayer material disclosed herein may be in thermal communication with an element of the cooling system of a battery module or battery pack (e.g., a cooling plate or cooling channel of the cooling system). As another example, at least one thermally conductive layer of the multilayer material disclosed herein may be in thermal communication with other elements of the battery pack, battery module, or battery system that can act as a heat sink (e.g., a wall of the battery pack, module, or system), or with other elements of the multilayer material disposed between battery cells. The thermal communication between the thermally conductive layer of the multilayer material and the heat sink element within the battery system allows excess heat to be transferred from one or more cells adjacent to the multilayer material to the heat sink, thereby reducing the impact, severity, or propagation of thermal events that may generate excess heat (e.g., as detailed herein).

[0161] Preferably, the thermally conductive layer has a melting temperature of at least 300°C, more preferably at least 600°C, more preferably at least 1000°C, and even more preferably at least 1500°C.

[0162] The thickness of the thermally conductive layer may depend on the composition, the characteristics of other components of the multilayer material (e.g., compression pads), the number of thermally conductive layers included in the multilayer material, and various compositional factors. Functionally, the thermally conductive layer should be thick enough to provide the required in-plane thermal conductivity.

[0163] In some embodiments, the thermally conductive material (e.g., a pyrolytic graphite sheet (PGS)) may have a thickness of about 0.010 mm, 0.025 mm, 0.05 mm, 0.07 mm, 0.10 mm, or within any two of these values, and an in-plane thermal conductivity in the range of about 600 to about 1950 W / mK. In some embodiments, the thermally conductive material (e.g., a metal sheet) may have a thickness of about 0.05 mm, about 0.07 mm, about 0.10 mm, about 0.20 mm, about 0.25 mm, about 0.30 mm, about 0.5 mm, about 0.75 mm, about 1 mm, about 1.5 mm, about 2 mm, about 3 mm, about 4 mm, about 5 mm, or within any two of these values.

[0164] In some embodiments, the thermally conductive material may be a phase change material.

[0165] In some embodiments, thermal paste may be used between the layers of the multilayer material to ensure uniform heat conduction between such layers. Thermal paste as used herein refers to various materials, also known as thermal compounds, thermal greases, thermal interface materials (TIMs), thermal gels, thermal adhesives, heat dissipation compounds, and heat dissipation pastes. For example, a layer of thermal paste may be provided between the aerogel composition and any other layer (e.g., one or more layers comprising thermally conductive or heat-capacitant materials, one or more overlay layers, or encapsulation layers).

[0165] Sacrificial Material Layer

[0166] In an example embodiment, the multilayer material may include a sacrificial material or a sacrificial material layer. In the context of this disclosure, the terms "sacrificial material" or "sacrificial layer" refer to a material or layer intended to be sacrificed or at least partially removed in response to mechanical, thermal, chemical, and / or electromagnetic conditions experienced by the layer. For example, the sacrificial material or sacrificial layer may decompose when exposed to high temperatures (e.g., high temperatures occurring before or during a battery thermal runaway event). In some embodiments, the sacrificial material layer may be disposed on an outer surface (e.g., the surface outside the core portion of the multilayer material) or an external surface (e.g., the outer surface of the multilayer material).

[0167] In exemplary embodiments, the sacrificial material or layer disclosed herein may include a compressible pad having a compressive modulus of about 1 MPa, about 2 MPa, about 3 MPa, about 4 MPa, about 5 MPa, about 6 MPa, about 7 MPa, about 8 MPa, about 9 MPa, about 10 MPa, about 11 MPa, about 12 MPa, or within any two of these values. The sacrificial material layer may be selected from the group consisting of siloxanes, polyolefins, polyurethanes, phenolic resins, melamine, cellulose acetate, and polystyrene. In some cases, the material layer is in the form of foam. In some embodiments, the compressible pad or foam may wear down due to exposure to mechanical (e.g., periodic) loads. In some embodiments, the compressible pad or foam decomposes after exposure to individual mechanical, chemical, and / or thermal events.

[0168] In some embodiments, the chemical decomposition initiation temperature of the sacrificial material layer is in the range of about 200°C to about 400°C.

[0169] Suitable foams used as compressible pads in the embodiments disclosed herein have a density of less than about 1.0 g / cc or less, about 0.90 g / cc or less, about 0.80 g / cc or less, about 0.70 g / cc or less, about 0.60 g / cc or less, about 0.50 g / cc or less, about 0.40 g / cc or less, about 0.30 g / cc or less, about 0.20 g / cc or less, about 0.16 g / cc, about 0.10 g / cc or less, about 0.08 g / cc or less, or in the range of any two of these values, and / or have a void volume content of at least about 20% to about 99%, specifically greater than or equal to about 30%, based on the total volume of the foam. In one example embodiment, the foam has a density of about 0.08 g / cc to about 0.50 g / cc, a 25% compressive force deflection (CFD) at about 27 kPa to about 55 kPa, and less than about 10%, specifically less than 5%, of compression set at about 70°C. The CFD is measured according to ASTM D1056 by calculating the force (in kPa) required to compress the sample to 25% of its original thickness.

[0170] The polymer used in the foam can be selected from a wide variety of thermoplastic resins, thermoplastic resin mixtures, or thermosetting resins. Examples of thermoplastic resins that may be used include polyacetal, polyacrylic acid, styrene-acrylonitrile, polyolefin, acrylonitrile-butadiene-styrene, polycarbonate, polystyrene, polyethylene terephthalate, polybutylene terephthalate, polyamide (e.g., but not limited to Nylon 6; Nylon 6,6; Nylon 6,10; Nylon 6,12; Nylon 11 or Nylon 12), polyamide-imide, polyarylate, polyurethane, ethylene propylene rubber (EPR), polyarylate, polyether ether, polyphenylene sulfide, polyvinyl chloride, polyether ether, polyetheramide, polytetrafluoroethylene, fluorinated ethylene propylene, polyvinyl chloride, polyvinylidene fluoride, polyvinyl fluoride, polyetherketone, polyetheretherketone, polyetherketoneketone, etc., or combinations including at least one of the above thermoplastic resins.

[0171] Examples of thermoplastic resin blends that can be used in the polymer foam include acrylonitrile-butadiene-styrene / nylon, polycarbonate / acrylonitrile-butadiene-styrene, acrylonitrile-butadiene-styrene / polyvinyl chloride, polyphenylene ether / polystyrene, polyphenylene ether / nylon, polyurethane / acrylonitrile-butadiene-styrene, polycarbonate / thermoplastic polyurethane, polycarbonate / polyethylene terephthalate, polycarbonate / polybutylene terephthalate, thermoplastic elastomer alloy, polyethylene terephthalate / polybutylene terephthalate, styrene-maleic anhydride / acrylonitrile-butadiene-styrene, polyetheretherketone / polyetheretherketone, styrene-butadiene rubber, polyethylene / nylon, polyethylene / polyacetal, ethylene propylene rubber (EPR), etc., or combinations including at least one of the above blends.

[0172] Examples of polymeric thermosetting resins that can be used in the polymer foam include polyurethane, epoxy resin, phenolic resin, polyester, polyamide, silicone, etc., or combinations of at least one of the above thermosetting resins. Mixtures of thermosetting resins and mixtures of thermoplastic resins and thermosetting resins can be used.

[0172] Multilayer materials

[0173] As described above, the multilayer material according to the embodiments of this disclosure provides good compressibility, compressive elasticity, and compliance. When used as a thermal insulation between batteries within a battery module, the thermally insulating sheet formed using the aerogel composition provides resistance to compressive deformation to accommodate battery expansion due to degradation and expansion of the active material during battery charge / discharge cycles. During the initial assembly of the battery module, a low load of 1 MPa or less is typically applied to the thermal insulation (e.g., the multilayer material disclosed herein). During use, for example, when the batteries within the battery module expand or expand during charge / discharge cycles, loads up to about 5 MPa may be applied to the multilayer material disclosed herein.

[0174] In one example embodiment, this disclosure provides a multilayer material wherein the multilayer material exhibits less than about 25% compressibility at about 25 kPa. Optionally, after compression release, the multilayer material may have sufficient elasticity to recover to at least about 80%, 75%, 65%, 60%, or 50% of its original thickness. In some embodiments, the multilayer material exhibits less than about 25% compressibility in the range of about 25 kPa to about 35 kPa, and preferably less than about 50% compressibility in the range of about 50 kPa. In some embodiments, the multilayer material exhibits compressibility in the range of about 25% to about 50% in the range of about 50 kPa. In an example embodiment, the multilayer material exhibits less than about 80% compressibility in the range of about 245 kPa, for example, less than about 70% in the range of about 235 kPa. In an example embodiment, the multilayer material exhibits less than about 70% compressibility in the range of about 345 kPa. When the multilayer material is compressed, the thermal conductivity of the multilayer material, including the reinforced aerogel composition, is preferably maintained at less than about 25 mW / m*K.

[0175] As described herein, the multilayer material may include multiple material layers, such as an insulating layer, a thermally conductive layer, a heat-capacitance layer, an encapsulating material layer, an abrasion-resistant layer, a fire-retardant / flame-retardant layer, a heat-reflective layer, a compressible layer (e.g., a compressible pad), a sacrificial layer, or a combination thereof. The combination and configuration of the layers in the multilayer material may be selected to obtain a desired combination of properties, such as compressibility, elasticity, thermal properties, fire reactivity, and other properties. In some embodiments, the multilayer material includes at least one compressible pad disposed between at least two layers of the reinforcing aerogel composition. For example, the compressible pad may be a foam or other compressible material, such as polyolefin, polyurethane, phenolic resin, melamine, cellulose acetate, or polystyrene. In certain embodiments, the multilayer material may also include at least one thermally conductive or heat-capacitance layer and at least one of the plurality of layers of the reinforcing aerogel composition. The thermally conductive or heat-capacitance material may absorb and / or disperse heat within the multilayer material. In some embodiments, the multilayer material may further include a heat-reflective layer. For example, the heat-reflective layer may include a metal foil or sheet.

[0176] In embodiments where the multilayer material comprises several layers, these layers may be attached to other layers, for example, by an adhesive mechanism selected from the group consisting of aerosol adhesives, urethane adhesives, acrylate adhesives, hot melt adhesives, epoxy resins, rubber resin adhesives, polyurethane composite adhesives, and combinations thereof. In some embodiments, these layers may be attached by a non-adhesive mechanism (e.g., a mechanism selected from the group consisting of flame bonding, needle punching, sewing, sealing bags, rivets, buttons, clips, wrapping, supports, and combinations thereof). In some embodiments, any combination of the above-described adhesive and non-adhesive mechanisms may be used to attach these layers together.

[0176] Final products of multilayer materials

[0177] The multilayer material according to embodiments of this disclosure can be formed into various final products. In the simplest configuration, the multilayer material can be in the form of a sheet. The sheet can be formed continuously or semi-continuously, for example, as a rolled product, or can be cut from a larger sheet or otherwise formed into a sheet having the desired size and shape. The sheet material can be used to form an insulating layer between battery cells. In other configurations, the reinforced aerogel composition can be formed into a bag, for example, a pouch cell to house the battery, or formed into a cylinder to house a cylindrical battery cell.

[0178] The multilayer material disclosed herein can be formed into a series of three-dimensional shapes, including panels, pipe preforms, half-shell preforms, elbows, joints, bags, cylinders, and other shapes frequently required for the application of insulating materials in industrial and commercial applications.

[0179] Unless otherwise expressly provided, the singular forms “a” and “the” used in this specification and the appended claims include plural references. Unless the context clearly provides otherwise, the term “or” used in this specification and the appended claims generally includes “and / or” in its meaning.

[0180] As used herein, “about” means approximately or close to, and in the context of describing a numerical value or range, refers to ±5% of the value. In one embodiment, the term “about” may include conventional rounding based on the significant figures of the numerical value. Furthermore, the phrase “about 'x' to 'y'” includes “about 'x' to about 'y'”.

[0181] The terms “composition” and “complex” used herein are used interchangeably.

[0182] The terms “compressible pad” and “compressible layer” used herein are used interchangeably.

[0183] In the context of this disclosure, the terms "aerogel," "aerogel material," or "aerogel matrix" refer to a gel comprising a framework of interconnected structures, a corresponding network having interconnected pores integrated within the framework, and containing a gas (e.g., air) as a dispersion interstitial medium, and characterized by the following physical and structural properties attributable to the aerogel (based on nitrogen porosity testing): (a) an average pore size in the range of about 2 nm to about 100 nm, (b) a porosity of at least 80% or more, and (c) a surface area of ​​about 100 m² / g or more.

[0184] Therefore, the aerogel materials disclosed herein include any aerogel or other open-cell materials that satisfy the defining elements described in the preceding paragraph; including materials that can be otherwise classified as dry gels, cryogels, dual gels, microporous materials, etc.

[0185] Aerogel materials can be further characterized by other physical properties, including: (d) a pore volume of about 2.0 mL / g or more, specifically about 3.0 mL / g or more; (e) a density of about 0.50 g / cc or less, specifically about 0.3 g / cc or less, more specifically about 0.25 g / cc or less; and (f) at least 50% of the total pore volume comprising pores having a pore size between 2 and 50 nm (although the embodiments disclosed herein include aerogel frameworks and compositions comprising pores having a pore size greater than 50 nm, as discussed in more detail below). However, satisfying these additional properties is not necessary for characterizing the compound as an aerogel material.

[0186] In the context of this disclosure, the term "aerogel composition" refers to any composite material that includes an aerogel material as a component of a composite. Examples of aerogel compositions include, but are not limited to, fiber-reinforced aerogel composites; aerogel composites including additive elements such as opacifiers; aerogel composites reinforced by an open-cell macroporous framework; aerogel-polymer composites; and composite materials incorporating aerogel microparticles, particles, granules, microspheres, or powders into solid or semi-solid materials, such as by binding agents, resins, cements, foams, polymers, or similar solid materials. Aerogel compositions are generally obtained by removing the solvent from the various gel materials disclosed herein. The resulting aerogel compositions may undergo additional processes or treatments. The various gel materials may also undergo additional processes or treatments known or available in the art before undergoing solvent removal (or liquid extraction or drying).

[0187] The aerogel compositions disclosed herein may include reinforced aerogel compositions. In the context of this disclosure, the term "reinforced aerogel composition" refers to an aerogel composition that includes a reinforcing phase in an aerogel material, wherein the reinforcing phase is not part of the aerogel framework itself.

[0188] In the context of this disclosure, the term "fiber-reinforced aerogel composition" refers to a reinforced aerogel composition comprising a fiber-reinforced material as a reinforcing phase. Examples of fiber-reinforced materials include, but are not limited to, discrete fibers, woven materials, dry-layered nonwoven materials, wet-layered nonwoven materials, needle-punched nonwoven materials, cotton wadding, nets, mats, felts, and / or combinations thereof.

[0189] The fiber reinforcement material may be selected from organic polymer-based fibers, inorganic fibers, carbon-based fibers, or combinations thereof. The fiber reinforcement material may include a range of materials, including but not limited to: polyester, polyolefin terephthalate, polyethylene naphthalate, polycarbonate (e.g., Rayon, Nylon), cotton (e.g., Lycra manufactured by DuPont), carbon (e.g., graphite), polyacrylonitrile (PAN), oxidized PAN, uncarbonized heat-treated PAN (e.g., manufactured by SGL carbon), glass or glass fiber-based materials (e.g., S-glass, 901 glass, 902 glass, 475 glass, E-glass), silica-based fibers such as quartz (e.g., Quartz manufactured by Saint-Gobain), Q-felt (manufactured by Johns Hopkins University). Manville (manufactured), Saffil (manufactured by Saffil), Durablanket (manufactured by Unifrax) and other silica fibers, Duraback (manufactured by Carborundum), polyarylamide fibers such as Kevlar, Nomex, Sontera (all manufactured by DuPont), Conex (manufactured by Taijin), polyolefins such as Tyvek (manufactured by DuPont), Dyneema (manufactured by DSM), Spectra (manufactured by Honeywell), other polypropylene fibers such as Typar, Xavan (both manufactured by DuPont), fluoropolymers such as PTFE (trade name Teflon) (manufactured by DuPont), Goretex (manufactured by WLGORE), and carbonized silica fibers such as Nicalon (manufactured by COI). Ceramics (manufactured by Ceramics), ceramic fibers such as Nextel (manufactured by 3M), acrylic polymers, wool, silk, hemp, leather, suede fibers, PBO-Zylon fibers (manufactured by Tyobo), liquid crystal materials such as Vectan (manufactured by Hoechst), Cambrelle fibers (manufactured by DuPont), polyurethane, polyamide, wood fibers, boron, aluminum, iron, stainless steel fibers, and other thermoplastic materials such as PEEK, PES, PEI, PEK, PPS. This glass or glass fiber-based fiber reinforcement can be manufactured using one or more techniques. In certain embodiments, it is desirable to use carding and cross-laying or air-laid processes to manufacture them. In example embodiments, carded and cross-laid glass or glass fiber-based fiber reinforcements have specific advantages over air-laid materials. For example, carded and cross-laid glass or glass fiber-based fiber reinforcements can provide a consistent material thickness for a given basis weight of reinforcement. In certain additional embodiments, it is desirable to further needle-punch the fiber reinforcement, interlacing the fibers in the z-direction, to enhance the mechanical and other properties of the final aerogel composition.

[0190] In the context of this disclosure, "thermal runaway" generally refers to a sudden and rapid increase in battery temperature and pressure due to various operating factors, which can correspondingly cause excessively high temperatures to propagate throughout the associated module. Potential causes of thermal runaway in such systems may include: battery defects and / or short circuits (internal and external), overcharging, battery puncture or rupture (e.g., in the event of an accident), and excessively high ambient temperatures (e.g., typically above 55°C). During normal use, the battery generates heat due to internal resistance. Under normal power / current loads and environmental operating conditions, the temperature within most lithium-ion batteries can be relatively easily controlled within the range of 20°C to 55°C. However, stress conditions (e.g., high power consumption at high battery / ambient temperatures, and defects in individual batteries) can dramatically increase localized heat generation. In particular, above critical temperatures, exothermic chemical reactions within the battery are activated. Moreover, chemical heat generation typically increases exponentially with temperature. Therefore, heat generation becomes far greater than available heat dissipation. Thermal runaway can cause battery ventilation and internal temperatures to exceed 200°C.

[0191] In the context of this disclosure, the term "foam" refers to a material comprising a framework of interconnected polymer structures having a substantially homogeneous composition, a corresponding network or aggregate of pores integrated within the framework, and formed by dispersing a certain proportion of gas in the form of bubbles in a liquid or resin foam material such that, upon curing of the foam material into a solid structure, the bubbles are retained as pores. Generally, foams can be manufactured using a wide variety of processes—see, for example, U.S. Patent Nos. 6,147,134, 5,889,071, 6,187,831, and 5,229,429. Therefore, the foam material of this disclosure includes any material that satisfies the defining elements described in this paragraph, including compounds that can be otherwise classified as OCMF materials, macroporous materials, etc. The foam as defined in this disclosure can be of the types of thermoplastic materials, elastomers, and thermosetting materials (duromers).

[0192] In the context of this disclosure, the terms "flexible" and "flexible" mean the ability of a material or composition to bend or flex without macroscopic structural failure. The insulation of this disclosure is capable of bending at least 5°, at least 25°, at least 45°, at least 65°, or at least 85° without macroscopic failure; and / or has a bending radius of less than 4 feet, less than 2 feet, less than 1 foot, less than 6 inches, less than 3 inches, less than 2 inches, less than 1 inch, or less than U inches without macroscopic failure. Similarly, the terms "highly flexible" or "highly flexible" mean a material capable of bending to at least 90° and / or having a bending radius of less than U inches without macroscopic failure. Furthermore, the terms "classified as flexible" and "categorized as flexible" refer to materials or compositions that can be classified as flexible according to ASTM C1 101 (ASTM International, West Conshohocken, PA).

[0193] The insulating layer disclosed herein may be flexible, highly flexible, and / or classified as flexible. The aerogel composition disclosed herein may also be draped. In the context of this disclosure, the terms "draped" and "drapeability" refer to the ability of a material to be bent or flexed to 90° or greater without macroscopic failure when having a radius of curvature of about 4 inches or less. The insulating layer according to a particular embodiment of this disclosure is flexible so that the composition is non-rigid and can be applied to and conform to a three-dimensional surface or object, or pre-formed into various shapes and configurations to simplify installation or application.

[0194] In the context of this disclosure, the terms "additive" or "additive element" refer to materials that may be added to the aerogel composition before, during, or after the manufacture of the aerogel. Additives may be added to modify or improve desired properties in the aerogel, or to counteract undesirable properties in the aerogel. Additives are typically added to the aerogel material before gelation to a precursor liquid, during gelation to a transitional material, or after gelation to a solid or semi-solid material.

[0195] Examples of additives include, but are not limited to, microfibers, fillers, reinforcing agents, stabilizers, thickeners, elastic compounds, opacifiers, coloring or coloring compounds, radiation-absorbing compounds, radiation-reflecting compounds, fire-retardant additives, corrosion inhibitors, thermally conductive components, components providing heat capacity, phase change materials, pH adjusters, redox adjusters, HCN mitigators, exhaust gas mitigators, conductive compounds, dielectric compounds, magnetic compounds, radar blocking components, hardeners, anti-shrinkage agents, and other aerogel additives known to those skilled in the art. In some embodiments, the component providing heat capacity may include a material having a specific heat capacity of at least about 0.3 J / (gC). In some embodiments, the material providing heat capacity has a specific heat capacity of at least about 0.5 J / (gC). For example, the material providing heat capacity may include metals such as aluminum, titanium, nickel, steel, iron, or combinations thereof. In some embodiments, the multilayer material may include one or more layers or coatings of the material providing heat capacity. In some embodiments, the multilayer material may include particles of the material providing heat capacity, disposed within one or more insulating layers comprising an aerogel composition.

[0196] In certain embodiments, the aerogel compositions, reinforced aerogel compositions, and multilayer materials disclosed herein can function during high-temperature events, for example, providing thermal protection during high-temperature events, as disclosed herein. A high-temperature event is characterized by a heat flux of at least about 25 kW / m², at least about 30 kW / m², at least about 35 kW / m², or at least about 40 kW / m² lasting for at least 2 seconds over an area of ​​at least about 1 cm². A heat flux of about 40 kW / m² is associated with the heat flux caused by a typical fire (Behavior of Charring Solids under Fire-Level Heat Fluxes; Milosavljevic, I., Suuberg, EM; NISTIR 5499; September 1994). In special cases, the high-temperature event is a heat flux of about 40 kW / m² lasting for at least 1 minute over an area of ​​at least about 10 cm².

[0197] In the context of this disclosure, the terms "thermal conductivity" and "TC" refer to a measure of the ability of a material or composition to transfer heat between two surfaces on either side of the material or composition (where a temperature difference exists between the two surfaces). Thermal conductivity is specifically measured as the amount of heat transferred per unit time and per unit surface area divided by the temperature difference. It is usually recorded in the International System of Units (SI) as mW / m*K (milliwatts per meter * Kelvin). The thermal conductivity of a material can be determined by test methods known in the art, including but not limited to the methods described in the following documents: Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus (ASTM C518, ASTM International, West Conshohocken, PA); a Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus (ASTM C177, ASTM International, West Conshohocken, PA); a Test Method for Steady-State Heat Transfer Properties of Pipe Insulation (ASTM C335, ASTM International, West Conshohocken, PA); a Thin Heater Thermal Conductivity Test (ASTM C1114, ASTM International, West Conshohocken, PA); Standard Test Method for Thermal Transmission Properties of Thermally Conductive Electrical Insulation Materials (ASTM D5470, ASTM International, West Conshohocken, PA).Determination of thermal resistance by means of guarded hot plate and heat flow meter methods (EN 12667, British Standards Institution, United Kingdom); or Determination of steady-state thermal resistance and related properties - Guarded hot plate apparatus (ISO 8203, International Organization for Standardization, Switzerland). Because different methods can lead to different results, it should be understood that, in the context of this disclosure, unless otherwise explicitly stated, thermal conductivity measurements are obtained according to ASTM C518 (Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus) at ambient atmospheric pressure, at a temperature of approximately 37.5°C, and under a compressive load of approximately 2 psi. Measurements reported according to ASTM C518 are generally closely related to any measurements taken according to EN 12667 with any relevant adjustments to that compressive load.

[0198] Thermal conductivity measurements can also be obtained under compression, at atmospheric pressure, and at a temperature of about 10°C. Thermal conductivity measurements at 10°C are typically 0.5-0.7 mW / mK lower than the corresponding thermal conductivity measurements at 37.5°C. In certain embodiments, the insulating layer disclosed herein has a thermal conductivity at 10°C of about 40 mW / mK or less, about 30 mW / mK or less, about 25 mW / mK or less, about 20 mW / mK or less, about 18 mW / mK or less, about 16 mW / mK or less, about 14 mW / mK or less, about 12 mW / mK or less, about 10 mW / mK or less, about 5 mW / mK or less, or within any two of these values.

[0199] In the context of this disclosure, the term "density" refers to a measure of the mass of a material or composition per unit volume. The term "density" generally refers to the apparent density of a material and the bulk density of a composition. Density is usually recorded as kg / m³ or g / cc. The density of a material or composition (e.g., aerogel) can be determined by methods known in the art, including but not limited to the methods described in the following documents: Standard Test Method for Dimensions and Density of Preformed Block and Board-Type Thermal Insulation (ASTM C303, ASTM International, West Conshohocken, PA); Standard Test Methods for Thickness and Density of Blanket or Batt Thermal Insulations (ASTM C167, ASTM International, West Conshohocken, PA); Determination of the apparent density of preformed pipe insulation (EN 13470, British Standards Institution, United Kingdom); or Determination of the apparent density of preformed pipe insulation (ISO 18098, International Organization for Standardization, Switzerland). Because different methods can lead to different results, it should be understood that, in the context of this disclosure, unless otherwise explicitly stated, density measurements are obtained under ASTM C167 (Standard Test Methods for Thickness and Density of Blanket or Batt Thermal Insulations) at 2 psi compression for thickness measurements.In specific embodiments, the aerogel material or composition disclosed herein has a density of about 1.0 g / cc or less, about 0.90 g / cc or less, about 0.80 g / cc or less, about 0.70 g / cc or less, about 0.60 g / cc or less, about 0.50 g / cc or less, about 0.40 g / cc or less, about 0.30 g / cc or less, about 0.25 g / cc or less, about 0.20 g / cc or less, about 0.18 g / cc or less, about 0.16 g / cc or less, about 0.14 g / cc or less, about 0.12 g / cc or less, about 0.10 g / cc or less, about 0.05 g / cc or less, about 0.01 g / cc or less, or within the range of any two of these values.

[0200] The hydrophobicity of an aerogel material or composition can be expressed as water vapor absorption. In the context of this disclosure, the term "water vapor absorption" refers to a measure of the potential of an aerogel material or composition to absorb water vapor. Water vapor absorption can be expressed as the percentage (by weight) of water absorbed or otherwise retained by the aerogel material or composition when exposed to water vapor under specific measurement conditions. The water vapor absorption of an aerogel material or composition can be determined by methods known in the art, including but not limited to those described in the following documents: Standard Test Method for Determining the Water Vapor Sorption of Unfaced Mineral Fiber Insulation (ASTM C1104, ASTM International, West Conshohocken, PA); Thermal insulating products for building applications: Determination of long term water absorption by diffusion (EN 12088, British Standards Institution, United Kingdom). Because different methods can lead to different results, it should be understood that, in the context of this disclosure, unless otherwise explicitly stated, water vapor absorption measurements are obtained under ambient pressure at 49°C and 95% humidity for 24 hours (modified from 96 hours according to ASTM C1104) according to ASTM C1104 (Standard Test Method for Determining the Water Vapor Sorption of Unfaced Mineral Fiber Insulation). In certain embodiments, the aerogel material or composition of this disclosure may have water vapor absorption of about 50 wt% or less, about 40 wt% or less, about 30 wt% or less, about 20 wt% or less, about 15 wt% or less, about 10 wt% or less, about 8 wt% or less, about 3 wt% or less, about 2 wt% or less, about 1 wt% or less, about 0.1 wt% or less, or within any two of these values. Compared to another aerogel material or composition, an aerogel material or composition with improved water vapor absorption will have a lower water vapor absorption / retention percentage relative to the reference aerogel material or composition.

[0201] The hydrophobicity of an aerogel material or composition can be represented by measuring the equilibrium contact angle of a water droplet at the interface with the surface of the material. The aerogel material or composition disclosed herein may have a water contact angle of about 90° or greater, about 120° or greater, about 130° or greater, about 140° or greater, about 150° or greater, about 160° or greater, about 170° or greater, about 175° or greater, or within any two of these values.

[0202] In the context of this disclosure, the terms "heat of combustion," "HOC," and "ΔHC" are measures of the heat released during the combustion or exothermic decomposition of a material or composition. Heat of combustion is typically recorded as the caloric heat released per gram of aerogel material or composition (cal / g), or as megajoules of heat released per kilogram of material or composition (MJ / kg). The heat of combustion of a material or composition can be determined by methods known in the art, including but not limited to those described in the following literature: Reaction to fire tests for products - Determination of the gross heat of combustion (calorific value) (EN ISO 1716, International Organization for Standardization, Switzerland; adopted by EN). In the context of this disclosure, unless otherwise stated, heat of combustion measurements are obtained according to the EN ISO 1716 standard (Reaction to fire tests for products - Determination of the gross heat of combustion (calorific value)).

[0203] In the context of this disclosure, all thermal analyses and related definitions refer to measurements performed in air at ambient pressure, starting at 25°C and increasing to 1000°C at a rate of 20°C per minute. Therefore, when measuring and calculating the thermal decomposition onset temperature, peak heat release temperature, peak heat absorption temperature, etc., any changes to these parameters must be taken into account (or the measurements must be repeated under these conditions).

[0204] In the context of this disclosure, the terms "thermal decomposition onset temperature" and "TD" refer to a measure of the lowest ambient temperature at which a rapid exothermic reaction occurs within a material or composition due to the decomposition of organic materials. Thermogravimetric analysis (TGA) can be used to measure the thermal decomposition onset temperature of organic materials within a material or composition. The TGA curve of a material describes the weight loss (mass percentage) of the material as it is exposed to increasing ambient temperature, thus representing thermal decomposition. The thermal decomposition onset temperature of a material can be correlated with the intersection of the following tangents to the TGA curve: the line tangent to the baseline of the TGA curve, and the line tangent to the TGA curve at the point of maximum slope during a rapid exothermic decomposition event associated with the decomposition of organic materials. In the context of this disclosure, unless otherwise stated, the TGA analysis provided in this paragraph is used to obtain measurements of the thermal decomposition onset temperature of organic materials.

[0205] The thermal decomposition onset temperature of a material can also be measured using differential scanning calorimetry (DSC). The DSC curve of a material describes the heat (mW / mg) released by the material as it is exposed to gradually increasing ambient temperature. The thermal decomposition onset temperature of the material can be correlated with the point in the DSC curve where the increase in ΔmW / mg (change in heat output) is greatest, thus indicating the exothermic generation of the aerogel material. In the context of this disclosure, unless otherwise explicitly stated, measurements of the thermal decomposition onset temperature using DSC, TGA, or both are obtained using a heating rate of 20°C / min, further defined in the preceding paragraph. DSC and TGA provide similar values ​​for this thermal decomposition onset temperature, and tests are often run simultaneously, thus results can be obtained from both.

[0206] In the context of this disclosure, the terms "endothermic decomposition onset temperature" and "TED" refer to a measure of the lowest ambient temperature at which an endothermic reaction occurs within a material or composition due to decomposition or dehydration. The endothermic decomposition onset temperature of a material or composition can be measured using thermogravimetric analysis (TGA). The TGA curve of a material describes the weight loss (mass percentage) of the material as it is exposed to increasing ambient temperature. The thermal decomposition onset temperature of a material can be correlated with the intersection of the following tangents to the TGA curve: the line tangent to the baseline of the TGA curve, and the line tangent to the TGA curve at the point of maximum slope during rapid thermal decomposition or dehydration of the material. In the context of this disclosure, unless otherwise stated, the measurement of the endothermic decomposition onset temperature of a material or composition is obtained using the TGA analysis provided in this paragraph.

[0207] In the context of this disclosure, the terms "furnace temperature rise" and "ΔTR" refer to a measure of the difference between the maximum temperature (TMAX) of a material or composition under thermal decomposition conditions and the baseline temperature (typically the final temperature, or TFIN) of the material or composition under thermal decomposition conditions. Furnace temperature rise is typically recorded in degrees Celsius or °C. The furnace temperature rise of a material or composition can be determined by methods known in the art, including but not limited to those described in the following literature: Reaction to fire tests for building and transport products: Non-combustibility test (EN ISO 1182, International Organization for Standardization, Switzerland; adopted by EN). In the context of this disclosure, unless otherwise stated, furnace temperature rise measurements are obtained according to conditions equivalent to EN ISO 1182 (Reaction to fire tests for building and transport products: Non-combustibility test). In specific embodiments, the aerogel compositions disclosed herein may have a furnace temperature rise of about 100°C or less, about 90°C or less, about 80°C or less, about 70°C or less, about 60°C or less, about 50°C or less, about 45°C or less, about 40°C or less, about 38°C or less, about 36°C or less, about 34°C or less, about 32°C or less, about 30°C or less, about 28°C or less, about 26°C or less, about 24°C or less, or any two of these values. In the context of compositional stability at high temperatures, for example, a lower furnace temperature rise of the first composition compared to the second composition would be considered an improvement of the first composition relative to the second composition. It is contemplated herein that the furnace temperature rise of the compositions is reduced when one or more fire-retardant additives are added, compared to compositions without any fire-retardant additives.

[0208] In the context of this disclosure, the terms "burning time" and "TFLAME" refer to a measure of the sustained combustion of a material or composition under thermal decomposition conditions, wherein "sustainable combustion" means that combustion lasts for 5 seconds or longer on any visible portion of a sample. Burning time is typically recorded in seconds or minutes. The burning time of a material or composition can be determined by methods known in the art, including but not limited to those described in the following literature: Reaction to fire tests for building and transport products: Non-combustibility test (EN ISO 1182, International Organization for Standardization, Switzerland; adopted by EN). In the context of this disclosure, unless otherwise stated, burning time measurements are obtained according to conditions equivalent to EN ISO 1182 (Reaction to fire tests for building and transport products: Non-combustibility test). In certain embodiments, the aerogel compositions disclosed herein have ignition times of about 30 seconds or less, about 25 seconds or less, about 20 seconds or less, about 15 seconds or less, about 10 seconds or less, about 5 seconds or less, about 2 seconds or less, or within any two of these values. In the context herein, for example, a ignition time of a first composition that is shorter than that of a second composition will be considered an improvement of the first composition relative to the second composition. It is contemplated herein that the ignition time of a composition is reduced when one or more fire-retardant additives are added, compared to a composition that does not contain any fire-retardant additives.

[0209] In the context of this disclosure, the terms "mass loss" and "ΔM" refer to a measure of the amount of material, composition, or composite lost or burned under thermal decomposition conditions. Mass loss is typically recorded as a weight percentage or wt%. The mass loss of a material, composition, or composite can be determined by methods known in the art, including but not limited to those described in the following literature: Reaction to fire tests for building and transport products: Non-combustibility test (EN ISO 1182, International Organization for Standardization, Switzerland; adopted by EN). In the context of this disclosure, unless otherwise stated, mass loss measurements are obtained according to conditions equivalent to EN ISO 1182 (Reaction to fire tests for building and transport products: Non-combustibility test). In certain embodiments, the insulating or aerogel compositions disclosed herein may have a mass loss of about 50% or less, about 40% or less, about 30% or less, about 28% or less, about 26% or less, about 24% or less, about 22% or less, about 20% or less, about 18% or less, about 16% or less, or within any two of these values. In the context herein, for example, a mass loss of the first composition that is less than that of the second composition will be considered an improvement of the first composition relative to the second composition. It is contemplated herein that the mass loss of a composition is reduced when one or more fire-retardant additives are added, compared to a composition that does not contain any fire-retardant additives.

[0210] In the context of this disclosure, the term "peak heat release temperature" refers to a measure of the ambient temperature at which the exothermic release due to decomposition is at its maximum. The peak heat release temperature of a material or composition can be measured using TGA analysis, microdifferential scanning calorimetry (DSC), or a combination thereof. DSC and TGA provide similar values ​​for the peak heat release temperature, and tests are often run simultaneously, thus providing results from both. In a typical DSC analysis, a heat flux versus temperature rise graph is plotted; the peak heat release temperature is the temperature at which the highest peak appears on such a curve. In the context of this disclosure, unless otherwise stated, the TGA analysis described in this paragraph is used to obtain measurements of the peak heat release temperature of a material or composition.

[0211] In the context of endothermic materials, the term "peak heat absorption temperature" refers to a measure of the ambient temperature at which endothermic absorption due to decomposition is at its minimum. The peak heat absorption temperature of a material or composition can be measured using TGA analysis, microdifferential scanning calorimetry (DSC), or a combination thereof. In a typical DSC analysis, a heat flux versus temperature rise graph is plotted, and the peak heat absorption temperature is the temperature at which the lowest peak value appears on such a curve. In the context of this disclosure, unless otherwise stated, the TGA analysis described in this paragraph is used to obtain measurements of the peak heat absorption temperature of a material or composition.

[0212] In the context of this disclosure, the terms "low flammability" and "low flammability" refer to a material or composition that satisfies the following combination of characteristics: i) furnace temperature rise of 50°C or less; ii) burning time of 20 seconds or less; and iii) mass loss of 50 wt% or less. In the context of this disclosure, the terms "non-flammable" and "non-flammable" refer to a material or composition that satisfies the following combination of characteristics: i) furnace temperature rise of 40°C or less; ii) burning time of 2 seconds or less; and iii) mass loss of 30 wt% or less. It is anticipated that the flammability of the composition (e.g., the combination of furnace temperature rise, burning time, and mass loss) will be reduced upon including one or more flammable additives, as described herein.

[0213] In the context of this disclosure, the terms "low flammability" and "low combustibility" refer to a low-flammability material or composition having a total heat of combustion (HOC) of less than or equal to 3 MJ / kg. In the context of this disclosure, the terms "non-flammability" and "non-combustible" refer to a non-flammable material or composition having a heat of combustion (HOC) of less than or equal to 2 MJ / kg. It is anticipated that the HOC of the composition will decrease upon the inclusion of one or more flammable additives, as described herein.

[0214] In the context of this disclosure, the term "hydrophobically bonded silicon" refers to silicon atoms within the framework of a gel or aerogel that include at least one hydrophobic group covalently bonded to the silicon atom. Examples of hydrophobically bonded silicon include, but are not limited to, silicon atoms in silicon dioxide groups within a gel framework, formed from a gel precursor including at least one hydrophobic group (e.g., MTE or DMD). Hydrophobically bonded silicon may also include, but is not limited to, silicon atoms in the gel framework or on the surface of the gel, which are treated with a hydrophobic agent (e.g., HMDZ) to impart or improve hydrophobicity by incorporating additional hydrophobic groups into the composition. The hydrophobic groups disclosed herein include, but are not limited to, methyl groups, ethyl groups, propyl groups, isopropyl groups, butyl groups, isobutyl groups, tert-butyl groups, octyl groups, phenyl groups, or other alternative or non-alternative hydrophobic organic groups known to those skilled in the art. In the context of this disclosure, the terms "hydrophobic group," "hydrophobic organic material," and "hydrophobic organic content" specifically exclude readily hydrolyzable organosilicon-bound alkoxy groups on the framework of the gel material, which are reaction products between organic solvents and silanol groups. These excluded groups can be distinguished from the hydrophobic organic content through NMR analysis. The amount of hydrophobic bound silicon contained in the aerogel can be analyzed using NMR spectroscopy (e.g., CP / MAS 29Si solid-state NMR). NMR analysis of aerogels allows for the characterization and relative quantification of M-type hydrophobic bound silicon (monofunctional silicon dioxide, such as TMS derivatives); D-type hydrophobic bound silicon (bifunctional silicon dioxide, such as DMDS derivatives); T-type hydrophobic bound silicon (trifunctional silicon dioxide, such as MTES derivatives); and Q-type silicon (tetrafunctional silicon dioxide, such as TEOS derivatives). By allowing the classification of specific types of hydrophobically bound silicon into subtypes (e.g., classifying T-type hydrophobically bound silicon into T1, T2, and T3 samples), NMR analysis can also be used to analyze the bonding chemistry of hydrophobically bound silicon contained in aerogels. Specific details related to NMR analysis of silicon dioxide materials can be found in Geppi et al., “Applications of Solid-State NMR to the Study of Organic / Inorganic Multicomponent Materials,” pp. 7–9 (Appl. Spec. Rev. (2008), 44-1: 1–89), which is incorporated herein by reference to the specific pages mentioned.

[0215] Characterization of hydrophobically bound silicon in CP / MAS 29Si NMR analysis can be based on the following chemical shift peaks: M1 (30 to 10 ppm); D1 (10 to -10 ppm), D2 (-10 to -20 ppm); T1 (-30 to -40 ppm), T2 (-40 to -50 ppm), T3 (-50 to -70 ppm); Q2 (-70 to -85 ppm), Q3 (-85 to -95 ppm), Q4 (-95 to -110 ppm). These chemical shift peaks are approximate and exemplary, and are not intended to be limiting or restrictive. Precise chemical shift peaks attributable to various silicon types within a material can depend on the specific chemical composition of the material and can generally be interpreted by those skilled in the art through routine experiments and analyses.

[0216] In the context of this disclosure, the terms "hydrophobic organic content" or "hydrophobic content" or "hydrophobic content" refer to the amount of hydrophobic organic material bonded to the framework in an aerogel material or composition. The hydrophobic organic content of an aerogel material or composition can be expressed as a weight percentage of the amount of hydrophobic organic material on the aerogel framework relative to the total amount of material in the aerogel material or composition. Those skilled in the art can calculate the hydrophobic organic content based on the properties and relative concentration of the materials used to manufacture the aerogel material or composition. The hydrophobic organic content can also be measured by thermogravimetric analysis (TGA) of the host material, preferably in an oxygen environment (although TGA in other gas environments can also be used). Specifically, the percentage of hydrophobic organic material in the aerogel can be correlated with the percentage of weight loss of the hydrophobic aerogel material or composition during the heat of combustion during the TGA analysis, and adjustments can be made for moisture loss, residual solvent loss, and loss of easily hydrolyzed alkoxy groups during the TGA analysis. Other alternative techniques, such as microdifferential scanning calorimetry, elemental analysis (especially carbon), chromatography, nuclear magnetic resonance spectroscopy, and other analytical techniques known to those skilled in the art, can be used to measure and determine the hydrophobic content in the aerogel compositions disclosed herein. In certain cases, a combination of known techniques may be useful or necessary for determining the hydrophobic content of the aerogel compositions disclosed herein.

[0217] The aerogel material or composition of the present invention may have a hydrophobic organic content of 50 wt% or less, 40 wt% or less, 30 wt% or less, 25 wt% or less, 20 wt% or less, 15 wt% or less, 10 wt% or less, 8 wt% or less, 6 wt% or less, 5 wt% or less, 4 wt% or less, 3 wt% or less, 2 wt% or less, 1 wt% or less, or any two of these values.

[0218] The term "fuel content" refers to the total amount of combustible material in an aerogel material or composition, which may be related to the percentage of weight loss of the aerogel material or composition at the heat of combustion temperature during TGA or TG-DSC analysis, and adjusted for moisture loss. The fuel content of an aerogel material or composition may include hydrophobic organic content, as well as other combustible residual alcohol solvents, fillers, reinforcing materials, and readily hydrolyzable alkoxy groups.

[0219] In the context of this disclosure, the term "organically modified silica" includes the aforementioned materials and other organically modified materials, sometimes referred to as "ormocer". Organically modified silica is commonly used as a coating in which an organically modified silica film is cast onto a substrate material by means of a sol-gel process or the like. Other examples of organic-inorganic hybrid aerogels disclosed herein include, but are not limited to, silica-polyether, silica-PMMA, silica-chitosan, carbides, nitrides, and other combinations of the aforementioned organic and inorganic aerogels forming compounds. U.S. Patent Application 20050192367 (paragraphs

[0022] -

[0038] and

[0044] -

[0058] ) includes teachings on such hybrid organic-inorganic materials and is incorporated herein by reference in accordance with separately mentioned sections and paragraphs.

[0219] Use of multilayer materials in battery modules or battery packs

[0220] Compared to traditional batteries, lithium-ion batteries (LIBs) are considered one of the most important energy storage technologies due to their high operating voltage, low memory effect, and high energy density. However, safety issues are a serious obstacle to the large-scale application of LIBs. Under abuse conditions, exothermic reactions can lead to the release of heat, which can trigger subsequent unsafe reactions. The situation worsens because the heat released from abusing the battery can activate a series of reactions, leading to catastrophic thermal runaway.

[0221] With the continuous improvement of energy density in lithium-ion batteries, enhancing their safety has become increasingly urgent for the development of electrical devices such as electric vehicles. The mechanisms that trigger safety issues vary for different battery chemistryes. This technology focuses on customizing multilayer materials and their corresponding configurations to achieve excellent thermal and mechanical properties. The multilayer materials of this technology provide an effective heat dissipation strategy under normal and thermal runaway conditions, while ensuring the stability of the LIB in normal operating modes (e.g., withstanding applied compressive stress).

[0222] The multilayer materials disclosed herein can be used to separate, insulate, and protect battery cells or battery assemblies having batteries of any configuration, such as pouch cells, cylindrical cells, prismatic cells, and assemblies and modules that include or contain any such batteries. The multilayer materials disclosed herein can be used in rechargeable batteries (e.g., lithium-ion batteries), solid-state batteries, and any other energy storage devices or technologies that require separation, insulation, and protection.

[0223] Passive devices such as cooling systems may be used in conjunction with the multilayer materials disclosed herein within the battery module or battery pack.

[0224] Multilayer materials according to various embodiments of the present disclosure are used in battery packs comprising a plurality of single cell units or battery cell modules to thermally separate the single cell units or battery cell modules from each other.

Claims

1. A multilayer material used as an insulation layer in an electrical energy storage system, the multilayer material comprising: The core component includes a layered assembly, which includes at least one insulating layer and at least one thermally resistant layer; The outer portion is disposed outside the core portion, the outer portion comprising at least one sacrificial material layer and at least one encapsulation material layer selected from polymers, elastomers, or combinations thereof, wherein the sacrificial material layer comprises a compressible pad; wherein the encapsulation material layer is sandwiched between the core portion and the sacrificial material layer of the outer portion, wherein the heat capacity layer has a specific heat capacity of at least 200 J / (kg-K), wherein the insulation layer has a thermal conductivity according to ASTM C518 standard, which is 50 mW / mK or less at 37.5°C and less than 60 mW / mK through the insulation layer thickness dimension, wherein the sacrificial material layer is in the form of foam, and wherein the heat capacity layer comprises metal.

2. A multilayer material used as an insulation layer in an electrical energy storage system, the multilayer material comprising: The core portion includes a layered assembly comprising at least one insulating layer and at least one thermally conductive layer; an outer portion disposed on the exterior of the core portion, the outer portion comprising at least one sacrificial material layer; and an encapsulating material layer sandwiched between the core portion and the sacrificial material layer; wherein the thermally conductive layer has a thermal conductivity of at least 200 mW / mK along its in-plane dimension at 37.5°C, as determined by ASTM C518; and wherein the insulating layer has a thermal conductivity of 50 mW / mK or less at 37.5°C and less than 60 mW / mK through its thickness dimension at 600°C, as determined by ASTM C518.

3. The multilayer material as described in claim 1 or 2, wherein, The multilayer material has an average thickness between 2 mm and 10 mm in its uncompressed state, obtained under 2 psi compression according to ASTM C167 standards.

4. The multilayer material as described in claim 1 or 2, wherein, The insulating layer comprises aerogel.

5. The multilayer material as described in claim 4, wherein, The aerogel includes reinforcing materials.

6. The multilayer material as described in claim 5, wherein, The reinforcing material includes fibers selected from organic polymer-based fibers, inorganic fibers, carbon-based fibers, or combinations thereof.

7. The multilayer material as described in claim 6, wherein, The fiber system is in the form of discrete fibers, woven materials, dry-layered nonwoven materials, wet-layered nonwoven materials, needle-punched nonwoven materials, cotton wadding, nets, pads, felts, and / or combinations thereof; and / or thereof. The inorganic fiber is selected from glass fiber, rock fiber, metal fiber, boron fiber, ceramic fiber, basalt fiber or a combination thereof.

8. The multilayer material as described in claim 6, wherein, The aerogel includes a silicon dioxide-based aerogel; and wherein the aerogel includes one or more additives, the one or more additives comprising at least 5 to 20 percent by weight of the aerogel.

9. The multilayer material as described in claim 8, wherein, The one or more additives constitute at least 10 to 20% by weight of the aerogel; and wherein: the one or more additives include fire-retardant additives; the one or more additives include opacifiers selected from B4C, diatomaceous earth, manganese ferrite, MnO, NiO, SnO, Ag2O, Bi2O3, TiC, WC, carbon black, titanium dioxide, ferric titanium dioxide, zirconium silicate, zirconium oxide, iron oxide (I), iron oxide (III), manganese dioxide, chromium oxide, or mixtures thereof; the one or more additives include: opacifiers comprising silicon carbide; and / or the one or more additives include a combination of fire-retardant additives and opacifiers.

10. A multilayer material as described in claim 1 or 2, wherein, The encapsulation material layer comprises a metal layer and one or more polymer layers, wherein the encapsulation material layer is disposed between the core portion and the outer portion.

11. The multilayer material as described in claim 1 or 2, wherein, The sacrificial material layer comprises materials selected from the group consisting of siloxanes, polyolefins, polyurethanes, phenolic resins, melamine, cellulose acetate, and polystyrene.

12. The multilayer material as described in claim 1 or 2, wherein, The chemical decomposition initiation temperature of the sacrificial material layer, measured using thermogravimetric analysis (TGA) or microdifferential scanning calorimetry (DSC) at a heating rate of 20°C / min, is in the range of 200°C to 400°C.

13. The multilayer material as described in claim 1 or 2, wherein, The insulating layer comprises materials selected from the group consisting of mica, microporous silicon dioxide, ceramic fibers, mineral wool, and combinations thereof.

14. The multilayer material as described in claim 2, wherein, The thermally conductive layer system includes at least one layer of metal, carbon, thermally conductive polymer, or a combination thereof, or wherein the thermally conductive layer includes a phase change material.

15. The multilayer material as described in claim 2, wherein, The thermally conductive layer system includes metals such as aluminum, copper, or steel.

16. The multilayer material as described in claim 2, wherein, This thermally conductive layer conducts heat away from the localized heat load.

17. The multilayer material as described in claim 16, wherein, This thermally conductive layer dissipates heat from the localized heat load to the environment.

18. A multilayer material as described in claim 1 or 2, wherein, The thermally conductive layer system is in the form of a group composed of mesh, sheet, perforated sheet, foil, and perforated foil.

19. The multilayer material as described in claim 1, wherein, The heat capacity layer is a phase change material.

20. A multilayer material as described in claim 1 or 2, wherein, The outer portion further comprises: a layer made of a material selected from the group consisting of abrasion-resistant materials, intumescent materials, fire-resistant materials, flame-retardant materials, or combinations thereof.

21. The multilayer material as described in claim 1 or 2, wherein, The insulating layer comprises materials selected from the group consisting of mica, microporous silica, ceramic fibers, mineral wool, and combinations thereof.

22. The multilayer material as described in claim 1 or 2, wherein, The thermal conductivity of the insulation layer, which extends through its thickness at 25°C, remains constant or increases only slightly under loads up to 5 MPa.

23. Use of a multilayer material as described in claim 1 or 2 in a battery pack comprising a plurality of single cell cells or battery cell modules for thermally separating the single cell cells or battery cell modules from each other.

24. The use as described in claim 23, wherein, An uncontrolled event occurring in one or more battery cells or battery cell modules of a portion of the battery pack will not cause damage to the multilayer material as described in any of claims 1 to 21, or to the battery cells or modules in the portion of the battery pack to which the uncontrolled event occurred.

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