Thermal insulation mat for a battery system

Abstract

The present invention relates to a thermal insulating pad (1) for insulating adjacent battery cells (2), particularly prismatic battery cells, in a battery system. The thermal insulating pad comprises an elastically deformable substrate (7) made of a fiber-elastomer composite structure. A defined number of ribs (8) are provided on two main surfaces of the substrate (7). These ribs extend laterally on the main surfaces of the substrate (7) in parallel and spaced apart from each other. The rib arrangement system on the two main surfaces is surrounded by a surrounding frame (10), and there is a gap (11) between the ribs (8) and the frame (10). The fiber-elastomer composite structure of the substrate (7) is formed by an elastomer matrix together with at least one intermediate layer made of mineral fibers embedded therein. The thermal insulating pad is also capable of compensating for the inherent volume changes of the battery cells due to chemical aging of the battery cell components and the periodic expansion and contraction of the battery cells during charging and discharging.

Description

Technical Field

[0001] The present invention relates to a thermal insulation pad for a battery system, particularly a lithium-ion battery system, wherein the thermal insulation pad is disposed between individual battery cells in order to prevent overheating from spreading to adjacent battery cells in the event of a battery cell failure, for example, due to overheating of the battery cell.

[0002] The thermal insulation pad according to the invention can be advantageously used in battery systems, such as those used in the field of electric vehicles. Background Technology

[0003] Battery systems typically consist of multiple individual cells to achieve the necessary high energy density. Here, a defined number of individual cells are combined into a module, and these modules are assembled into a battery stack and electrically connected to each other. The resulting battery system is housed in a sealed enclosure to protect it from external influences.

[0004] In principle, battery types can be categorized into cylindrical battery cells, prismatic battery cells, and pouch battery cells. Prismatic battery cells have a cuboid shape with a rigid casing (also known as a battery cell cup), while pouch cells, also known as coffee pouch battery cells, have a flexible casing made of membrane.

[0005] This invention relates particularly to battery systems with rechargeable batteries, also known as secondary battery cells or accumulators. For example, battery systems commonly used in the electric vehicle sector are lithium-ion battery systems.

[0006] To ensure the operational safety of a battery system composed of multiple individual battery cells, it is essential to prevent the fire from spreading to adjacent battery cells or even burning down the entire battery system (thermal runaway) in the event of a fire in one battery cell, for example, due to overheating.

[0007] When a battery cell catches fire, temperatures can reach 600°C or higher within seconds. To prevent overheating and the spread of the fire to adjacent battery cells, measures must be taken to prevent the temperature of adjacent battery cells from rising above a critical value.

[0008] In lithium-ion batteries, the critical temperature value is determined by factors such as the electrolyte or electrolyte composition and the trigger range of the shut-off separator.

[0009] Lithium-ion battery cells use a liquid electrolyte that includes flammable components with a boiling point of around 100°C. Therefore, the cell temperature must be maintained below this boiling point to prevent pressure buildup within the sealed cell. If the internal pressure of the cell becomes too high, a safety valve opens, releasing the resulting gas, and under these conditions, the highly reactive electrolyte will typically ignite immediately.

[0010] A shut-off separator is a safety measure used to suppress ion transport and interrupt current by closing the micropores of the separator when a critical temperature is exceeded. Such shut-off separators are known to consist of a laminated structure comprising two polymer films, each with a different melting point.

[0011] For example, a commonly used shut-off separator is made of a polyethylene / polypropylene laminate, where polyethylene has a melting point of 120°C and polypropylene has a melting point of 170°C. If the melting point of the lower polymer membrane (here, polyethylene) is exceeded, the polymer membrane melts, closing the pores of the higher-melting-point polymer membrane (here, polypropylene).

[0012] As can be seen from the above, the battery cell temperature must be kept below 150°C, especially below 120°C, and preferably below 100°C as much as possible, to prevent the battery cell from overheating and the associated safety risks.

[0013] It is known that thermal insulation devices must be installed between adjacent battery cells to prevent the temperature of adjacent battery cells from rising above the critical temperature and thus causing the battery cells to catch fire.

[0014] Besides thermal insulation, other aspects need to be considered for the safe operation of battery systems.

[0015] Thus, the thermal insulation structure should also function as an electrical insulator to achieve electrical insulation between battery cells or electrical insulation of the potential difference on the battery cell housing between battery cells in a module.

[0016] Another important aspect of lithium-ion battery system design is the volume change (also known as expansion) associated with the battery cell and the system. This is due, on the one hand, to the continuous expansion of the battery cell due to the chemical aging of the battery cell components, and on the other hand, to the periodic expansion and deflation of the battery cell during charging and discharging.

[0017] Especially when manufacturing battery systems based on prismatic battery cells, the inherent volume variations of such systems must be considered due to the fixed battery cell housing. Here, the increased volume of the battery cell assembly causes a bulge in the central region of the large main surface. Conversely, the edge regions achieve mechanical stability through the corners of adjacent surfaces.

[0018] For prismatic batteries used in automotive applications, which typically have a diameter of 236 mm, a height of 115 mm, and a thickness of 32 mm, the main surface may bulge by 0.2 mm to less than 1 mm when charging an aging prismatic battery. Therefore, for modules that typically have 10 to 14 battery cells, a total expansion of 2 mm to less than 10 mm may occur.

[0019] Therefore, in addition to providing thermal and electrical insulation to adjacent battery cells, the thermal insulation pad should also be able to advantageously compensate for the volume expansion of the battery cells during their lifespan, including periodic volume changes and continuous volume increases during charging and discharging.

[0020] In addition, thermal insulation pads should be as lightweight as possible, space-saving for installation, and economical.

[0021] Thermal insulation means that when a battery cell catches fire at 600°C or higher within just 30 seconds, heat transfer to adjacent battery cells should be advantageously limited to below 100°C.

[0022] To ensure compensation for volume changes in the battery cell during its service life, the material must be elastically deformable and have sufficiently low residual stress deformation so that it does not settle under stress loads and temperature fluctuations.

[0023] In addition, it should be considered that, in order to form modules, a desired number of individual battery cells, typically 12 to 14, are combined into a battery stack, and the individual battery cells are pressed together and fixed under a determined preload force, for example, 5 to 19 kN, to obtain a determined battery stack geometry.

[0024] The thermal insulation pad must be able to withstand the preload throughout its entire service life to ensure the dimensional stability of the module. Summary of the Invention

[0025] According to the present invention, the above-mentioned problem can be solved by a thermally insulating pad having an elastically deformable substrate made of a fiber-elastomer composite structure. A number of ribs are provided on two main surfaces of the substrate, these ribs extending laterally on the main surfaces of the substrate in a parallel and spaced-apart manner. The ribs on the two main surfaces are staggered, and the substrate with the rib structure is surrounded by a surrounding frame, the ribs being detached from the frame. The frame is preferably also formed of an elastomeric material.

[0026] The “staggered arrangement” of ribs refers to the fact that the ribs on one main surface of the substrate extend within the spacing between two ribs on another main surface of the substrate.

[0027] The spacing between ribs should be wider than the width of the ribs extending above them, so as to allow the ribs to be elastically pressed into the spacing.

[0028] "Disconnection" means that the rib is not connected to the frame, that is, the end face of the rib and the outer surface of the corresponding outermost rib are not in contact with the frame.

[0029] The size of the thermal insulation pad according to the invention depends on the intended use.

[0030] In the form described herein, the thermal insulation pad is specifically designed for use between prismatic battery cells. However, the thermal insulation pad can also be easily adapted for use with other types of batteries.

[0031] For use as an intermediate insulator in a prismatic battery cell, the thermal insulation pad has a generally rectangular basic shape. In the installed state, the periphery of the thermal insulation pad may be flush with the periphery of the battery cell. Alternatively, the frame or the edge of the frame may protrude beyond the periphery of the battery cell, for example, along its long side, its short side, or both.

[0032] The elastically deformable substrate has a rectangular shape with two main surfaces. A number of ribs are provided on each main surface. These ribs are arranged parallel to each other and spaced apart from each other, and extend laterally on the main surface. The ribs on the two main surfaces are staggered from each other.

[0033] The substrate with the rib arrangement system is surrounded by a surrounding frame.

[0034] According to the invention, the thermal insulation pad is disposed between adjacent prismatic battery cells in a manner where the main surface is attached to the main surface. In the installed state, the free upper side of the frame abuts against adjacent battery cells or multiple battery cells.

[0035] In the assembled state, the frame of the thermal insulation pad extends along the dimensional rigid edge of the battery cell and can be supported on said edge.

[0036] In this way, the preload pressure applied to the frame of the battery cell and thermal insulation pad during module construction can be absorbed and compensated by the surrounding frame.

[0037] The frame can only deform slightly at most due to the preload pressure, and has correspondingly low compressibility.

[0038] The compressive strength of the frame can be influenced and adjusted in different ways and forms by the elasticity of the material, the width of the frame, and the frame structure.

[0039] For example, the frame height can be selected based on the compressive modulus of the elastic material used to manufacture the frame, such that the desired frame thickness is obtained after clamping during module construction.

[0040] The bulging of the main surface of the battery cell due to aging and volume increase during the charging process is compensated by ribs connected to an elastically deformable substrate, as explained in detail below.

[0041] If pressure is applied to the ribs of the adjacent thermally insulating pads according to the invention due to bulging of the main surface of the battery cell, the ribs will shift into the gap between the ribs located below the corresponding ribs and disposed on the other side of the substrate due to substrate deformation. When the pressure is released, for example, when the bulging subsides due to discharge, the ribs can return to their initial state due to the elasticity of the substrate.

[0042] The elastically deformable substrate, together with the ribs provided thereon, acts as a spring element, which is elastically pressed in when subjected to pressure load and pops out to the initial state when the pressure is unloaded.

[0043] According to an advantageous design, adjustable pressure can be applied to the surface of the battery cells via a substrate acting as a spring element, along with ribs disposed thereon, thereby slightly compressing the battery cell stack in addition to a preload pressure. It has been demonstrated that this additional pressure can positively impact the cycle stability of the battery cells in the stack.

[0044] The degree of elastic compression can be controlled by a series of different measures, which can be used individually or in combination of two or more measures.

[0045] In this way, the degree of elastic compression can be geometrically controlled by the spacing between the ribs, which should be at least 1.5 to 2 times the width of the ribs.

[0046] Compared to the rib width, the wider the spacing, the greater the deformability of the structure composed of the substrate and the ribs, that is, the ribs together with the substrate can be pressed deeper into the spacing.

[0047] Furthermore, the degree of elastic pressing is also determined by the structure and materials used for the substrate.

[0048] The substrate is formed of a fiber-elastomer composite structure having a matrix made of elastic plastic (elastomer) and at least one interlayer made of fiber (also called fiber interlayer) embedded in the matrix.

[0049] In addition to the necessary elasticity, the elastomer must also have sufficient heat resistance to withstand the high temperatures that would occur in the event of a battery fire.

[0050] Examples of suitable high-temperature resistant elastomers include silicone elastomers such as methyl phenyl silicone rubber (PMQ), methyl phenyl vinyl silicone rubber (PVMQ), methyl silicone rubber, methyl vinyl silicone rubber (VMQ), fluorovinyl methyl silicone rubber (FVMQ), ethylene-propylene-diene rubber (EPDM), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), natural rubber (NR), butyl rubber, isobutylene-isoprene rubber (IIR) and isoprene rubber (IR), and polyurethane (PUR).

[0051] The elasticity of the elastomer is preferably in the range of 20 to 80 Shore A, especially 45 to 75, and particularly preferably in the range of 50 to 60.

[0052] For desired heat resistance, mineral fibers such as glass fibers, basalt fibers, silicate fibers, and oxide ceramic fibers are used for the intermediate layer made of fibers.

[0053] The mineral fibers can exist in the form of surface structures, such as fabrics or nonwovens, and the surface structures themselves can be made of rovings or yarns composed of these fibers.

[0054] A surface density of 20 g / m³ is typically used. 2 Up to 200g / m 2 The fibers. If, for example, two or more fiber intermediate layers are provided, the areal density of each layer may be in the lower range or even lower.

[0055] Fibers are embedded in an elastomer matrix as reinforcing interlayers. When there are two or more fiber interlayers, a thin layer made of elastomer as an adhesive can be provided between the individual fiber interlayers.

[0056] A preferred material combination for the substrate is a silicone elastomer together with one or two intermediate layers made of glass fiber fabric.

[0057] In addition to the type of elastomer, the deformability of the substrate and the degree of elastic indentation therefrom are also determined by the fiber orientation.

[0058] The 0° / 90° orientation exhibits the lowest deformability, resulting in little or no elastic compression. Conversely, fibers at ±45° orientations demonstrate the greatest fiber displacement along with the greatest elastic compression between ribs.

[0059] An example of a suitable orientation between these values ​​is a 30° / 120° orientation.

[0060] During elastic pressing, the substrate elongates in the longitudinal direction, and the angle between the fibers decreases, meaning that an interaction occurs between the matrix and the fibers.

[0061] Furthermore, elasticity can be altered by adding inorganic fillers to the elastomer matrix. In this case, the fillers can perform purely mechanical functions. When the elastomer deforms, the spacing between the filler particles decreases until the particles come into contact, thereby preventing further deformation of the elastomer.

[0062] The performance of this blocking effect is influenced by a range of parameters, such as filler density, particle size and shape, and particle size distribution (single, dual, or trimodal). For example, particle shape, such as round or angular, affects the sliding and blocking properties between particles and within the matrix.

[0063] The filler can, in principle, have ceramic, carbon-based, or metallic properties. However, when selecting the filler, the thermal and electrical properties of the filler must be considered in light of the basic thermal and electrical insulation function of the thermal insulation pad according to the present invention.

[0064] Therefore, fillers with the lowest possible conductivity, such as ceramic fillers, are preferred.

[0065] In addition to adjusting mechanical and electrical properties, fillers can also be added to improve the thermal properties of elastomers.

[0066] For example, fillers that reduce thermal conductivity can be used. These can be materials that form insulating air cushions or pads, such as hollow bodies like hollow glass spheres, or materials with high porosity, such as aerogels, aerosols, or expanding materials.

[0067] Fillers that undergo an endothermic reaction at the ignition temperature and absorb heat from the system can also be used. These include, for example, materials that are ceramicized, vitrified, or carbonized at the ignition temperature, have a cooling effect, and can absorb oxygen, such as materials known in principle as flame retardants for plastics.

[0068] Suitable examples are metal hydroxides or metal hydroxy oxides, which decompose into water and form a protective ceramic layer when heated, such as aluminum hydroxide (aluminum trihydrate (ATH)), which reacts from about 200°C to form Al2O3 and water, or magnesium hydroxide, which reacts from about 300°C to form MgO and water.

[0069] Other suitable examples of heat-absorbing fillers are based on polyphosphates, such as melamine or ammonium polyphosphate, which expand (swell) upon decomposition to ammonia (NH3) and absorb oxygen through the reaction of ammonia to form nitrogen and water.

[0070] In principle, material properties can be advantageously tailored and adapted by changing the filler and its filling degree. The achievable filling degree depends largely on the particle size distribution, particle size, and surface reactivity of the filler particles. For example, a filling degree of up to 60% by weight can be achieved for particles with a predominantly 10-100 μm size, and for nanoscale particles, the filling degree can far exceed 100% by volume.

[0071] All fillers are provided on the premise that they do not adversely affect the elastic properties of the elastomer.

[0072] According to an advantageous embodiment, channels can be provided in the thermal insulation pad according to the invention, when needed, for venting gases formed by the reaction of the filler and the thermal decomposition of the elastomer. These channels prevent overpressure from forming in the area between the battery cell wall and the thermal insulation pad within the module, which is essentially sealed off due to preload pressure.

[0073] For this purpose, transversely extending interruptions can be provided in the ribs and / or outlets can be provided in the surrounding frame.

[0074] The reacting gases that may form can then be distributed along the interrupted portion on the substrate surface and escape through the outlet.

[0075] A particularly advantageous feature is that the interruption portion has a continuous arrangement. Here, the interruption portions in adjacent ribs are arranged in each other's extensions, thereby forming a continuous channel interrupted by the spacing between the ribs. Due to this continuous arrangement of the interruption portions, gas can escape in a directional manner.

[0076] As already mentioned, the dimensions and structure of the thermal insulation pad according to the invention are determined by the requirements of the specific application. For use in battery systems composed of prismatic battery cells, such as as a thermal intermediate insulation element in modules, the thermal insulation pad should have the thinnest possible overall thickness.

[0077] Under no load, the thickness should preferably not exceed 3 mm, while the rib height is 0.4 to 0.5 mm, the rib width is in the range of 1.0 to 3.0 mm, the spacing between ribs is in the range of 1.5 to 3 times the rib width, and the frame thickness is 5 to 10 mm.

[0078] Under a preload of 5 kN on the battery module, the total thickness of the thermal insulation pad is advantageously 1.5 mm or less, especially 1 mm or less.

[0079] Of course, these values ​​are just examples and can be easily changed according to specific requirements.

[0080] According to another advantageous embodiment, an intermediate layer consisting of a metal foil, such as aluminum foil, that reflects infrared radiation can be additionally disposed in the substrate. To save space, the foil should be as thin as possible, for example, about 0.1 mm.

[0081] To manufacture the thermal insulation pad according to the invention, common manufacturing methods can be employed, such as those known for manufacturing components from fiber-reinforced plastics. One example is the use of casting or pressing methods when a molding die is designed according to the desired structure of the component. In this way, for example, a first elastomeric layer for forming the rib structure and, if necessary, a structure for surrounding the frame can be first laid in the mold; then fibrous material for the fiber intermediate layer can be placed; and subsequently, the mold can be filled with another elastomeric material to impregnate the fibers and establish additional rib structures and, if necessary, a frame structure.

[0082] The present invention provides a thermal insulation pad that can meet all desired requirements for practical applications:

[0083] The thermal insulation pad exhibits the following thermal insulation properties: with a material thickness of approximately 1.5 mm and a hot-side temperature of 700°C, the thermal insulation pad remains stable at a temperature below 100°C on the cold side.

[0084] • The substrate made of a fiber-elastomer composite structure can be compressed by at least 0.4 mm to compensate for the bulging of the battery cells due to battery cell aging and charging cycles;

[0085] • Only a small amount of residual pressure deformation allows for displacement compensation while maintaining preload pressure in the battery cell complex throughout the entire lifespan of the battery module.

[0086] • For the desired electrical insulation performance, the breakdown voltage can be set to at least 3kV;

[0087] • For the desired low packaging density of battery systems, low space requirements can be maintained;

[0088] Furthermore, this thermal insulation pad can be manufactured simply and economically. Attached Figure Description

[0089] The thermal insulation pad of the battery cell according to the present invention will now be described in detail with reference to the accompanying drawings, which schematically illustrate one embodiment of the thermal insulation pad according to the present invention, such as a thermal insulation pad suitable for a prismatic battery cell.

[0090] in:

[0091] Figure 1A top view is shown of an arrangement system according to the invention, comprising four prismatic battery cells together with a thermally insulating pad disposed therebetween.

[0092] Figure 2 The image shows a side view of a prismatic battery cell in its bulging state.

[0093] Figure 3 A top view of the thermal insulation pad according to the present invention is shown.

[0094] Figure 4 Showing according to Figure 3 A side view of the thermal insulation pad according to the present invention.

[0095] Figure 5a Showing according to Figure 4 A cross-sectional view of the thermal insulation pad according to the invention along a rib and frame in an unloaded state.

[0096] Figure 5b It is shown that under the condition of being subjected to compressive load, according to Figure 5a The illustration,

[0097] Figure 6 A schematic exploded view of the frameless thermal insulation pad according to the present invention is shown.

[0098] Figure 7 The illustration schematically shows a load-bearing (elastically indented) state with staggered ribs.

[0099] Figure 8a A top view of the basic structure of the substrate made of the fiber-elastomer composite structure according to the present invention is shown in a state free from load.

[0100] Figure 8b The figure shown is based on the condition under load (elastic compression). Figure 8a The structure,

[0101] Figure 9a An embodiment of a basic structure of a substrate made of a fiber-elastomer composite structure and filled with filler is schematically shown under unloaded conditions.

[0102] Figure 9b Schematic illustration of the following under load (elastic compression) conditions: Figure 9a The structure,

[0103] Figure 10 A schematic top view of a thermal insulation pad according to the invention, showing one embodiment with a channel structure for gas venting, is shown.

[0104] Figure 11 A graph showing the results of heat transfer measurements performed on a sample manufactured according to the present invention;

[0105] Figure 12 A graph showing the spring characteristic curve of a specimen manufactured according to the present invention in relation to the rib spacing is provided.

[0106] Figure 13 A graph showing the correlation between the spring characteristic curve of the sample manufactured according to the present invention and the hardness (Shore A) of the silicon elastomer; and

[0107] Figure 14 A graph showing a comparison of the deformation properties of the specimens manufactured according to the present invention with the correlation between the rib spacing. Detailed Implementation

[0108] Figure 1 A battery device according to the prior art is shown, having four prism-shaped battery cells 2, with a thermally insulating pad 1 according to the invention provided between each two adjacent battery cells 2.

[0109] The internal structure of battery cell 2 is sealed by a solid cuboid or prismatic battery casing, which has two connection terminals 3 and 4 and a safety valve 5 on one narrow side. When the internal pressure of the battery cell rises above a critical value due to the reaction gas formed by the increase in temperature, the safety valve 5 opens, allowing the gas to escape and preventing the battery cell from exploding.

[0110] Figure 2 A prismatic battery cell 2 is shown, where the main surface 6 of the battery cell housing bulges. This deformation occurs primarily in the central region of the main surface 6, as the edges of the battery housing are mechanically stable through the corners of the adjacent smaller sides and do not deform during normal operation.

[0111] Figure 3 This is a top view of the thermal insulation pad 1 according to the invention, showing the rib arrangement system of the thermal insulation pad according to the invention. The thermal insulation pad has a substrate 7 and a row of ribs 8, which extend laterally on the substrate 7, parallel to each other and spaced apart by a distance 9. Here, the distance 9 is wider than the ribs 8.

[0112] The rib arrangement system is surrounded by a surrounding frame 10, and the ribs 8 are detached from the frame 10, that is, the ribs 8 do not contact the frame 10. The end face of the ribs 8 and the side face of the outer ribs are not connected to the frame 10, thus there is a gap 11 between the end face of the ribs 10 and the frame 8.

[0113] Here, the frame 10 has a flat, free upper side through which it rests against the edge surrounding the battery cell in the installed state. In the illustrated design, the frame 10 is also wider than the rib 8, thus the frame has higher deformation resistance than the rib. In the installed loaded state, the frame 10 can compensate for preload pressure, which does not affect the rib.

[0114] Figure 4 The illustration shows the thermal insulation pad 1 according to the invention in a view taken from a frontal angle. The arrangement of the ribs 8 on the upper main surface of the substrate 7 and the surrounding frame 10, which extends around the upper and lower rib arrangement system together with the substrate 7 disposed therebetween, can be clearly seen. The substrate 7 has an intermediate layer 12 made of fibrous material.

[0115] exist Figure 5a and 5b The image shows a longitudinal sectional view along a rib 8 and through the surrounding frame 10, in an unloaded state. Figure 5a (and the state of the load when the frame 10 is pressure-loaded by pre-tightening pressure during battery module assembly.)

[0116] When unloaded, the height of the frame 10 is greater than the height of the rib 8, and there is a gap 11 between the end face of the rib 8 and the frame 10, which extends around the entire rib arrangement system.

[0117] Figure 5b The diagram shows the state under preload pressure applied to the battery module during assembly. Under this preload pressure, the frame 10 is compressed in height, at which point the heights of the frame 10 and the rib 8 are equal. A gap 11 is also created when pressure is applied to the frame 10, allowing the rib 8 to disengage from the surrounding frame 10 during pressure loading.

[0118] The desired deformation resistance can be adjusted by varying the width of the frame, where the deformation resistance increases with the width. Furthermore, the deformation resistance can be tailored by selecting materials, the degree of crosslinking of the elastomer, and the compressive modulus.

[0119] As a result, in the assembled module having the thermal insulation pad 1 according to the invention disposed between the two battery cells 2, the frame 10 is loaded with preload pressure, but the ribs 8 remain substantially unloaded.

[0120] Figure 6 An exploded view of one embodiment of the thermal insulation pad 1 according to the invention is shown, wherein the surrounding frame 10 is omitted for the purpose of showing the structure.

[0121] As can be seen, the ribs 8 are arranged on the main surface of the substrate 7. Here, the ribs 8 are arranged parallel to each other and spaced apart from each other by a distance 9 on each main surface, and the ribs 8 extend laterally on the main surface.

[0122] Here, the spacing 9 between the ribs 8 on a main surface is greater than the width of the ribs 8, and the spacing 9 is preferably at least 1.5 to 2 times the width of the ribs 8.

[0123] Ribs on the two main surfaces are staggered, with one rib 8 on one main surface extending along a spacing 9 on the other main surface.

[0124] The substrate 7 is formed of an elastomeric material having an intermediate layer made of mineral fibers 12.

[0125] If, according to other embodiments, one or two additional intermediate layers made of fibrous material 12 are provided, an additional elastomeric material can be provided as an adhesive between the two intermediate layers made of fibrous material.

[0126] For manufacturing the substrate 7 with the intermediate layer made of fiber material 12 and for the ribs 8, the same elastomeric material can be used, whereby the ribs 8 can be formed as an integral part of the substrate 7. The frame 10 can also be made of the same elastomeric material and formed together with the substrate 7 as an integral part of the substrate 7.

[0127] like Figure 7 As shown, during the process of the main surface of the battery cell continuously bulging and increasing (not shown here), pressure is applied to the rib 8, and the rib 8 and the substrate 7 located below it are pressed into the spacing 9 of the rib 8 which is staggered on the main surface of the substrate 7.

[0128] In this elastically pressed state, the substrate 7 forms a zigzag pattern with alternating upward or downward arches extending into the corresponding spacing 9. When the pressure load decreases, for example during battery cell discharge, these deformations are restored accordingly due to the elasticity of the substrate 7.

[0129] The degree of deformation is primarily determined by the width of the spacing 9 and the deformability of the substrate 7, which is particularly affected by the elastomer's hardness (elasticity) and fiber orientation, and as in Figure 8a As exemplarily shown in 9a, 9b and 9a, 9b.

[0130] Figure 8a b and Figure 9a b. Using internal structures in an unloaded state ( Figure 9a and 10 a) and under the state of elastic compression ( Figure 9b and 10The schematic diagrams in b) show top views of the substrate 7 with the fiber interlayer 12.

[0131] The fibers in the fiber intermediate layer 12 have orientations of ±45°, resulting in fibers with different signs crossing at an angle of 90° 14a. The elastomeric matrix 13 in which the fibers are embedded is shown as a gray surface. Ribs 8 extending laterally on this surface are also shown. The edges extending along the ribs 8 on the left and right sides indicate the spacing 9 between the staggered ribs 8 located on the underside of the substrate 7.

[0132] In the unloaded state shown here, fibers with different symbols cross at an angle of 90° 14a.

[0133] As in Figure 8b As shown, if pressure is applied to the thermal insulation pad 1 and the ribs 8 are elastically pressed in, the fiber-matrix composite structure of the substrate 7 (shown by the left or right pointing arrows) elongates while its width decreases (shown by the arrows at the upper and lower edges in the figure). Therefore, the cross angle 14b between the fibers decreases, here to 60°.

[0134] As in Figure 9a In the state of being unloaded and in Figure 9b As shown in the elastically pressed state, similar changes occur when pressure is applied and elastically pressed onto the ribs 8 of the substrate to which filler particles 15 are added to the elastomeric material.

[0135] Here, in the fiber intermediate layer 12 with a cross angle of 90°, there is also a fiber orientation of ±45°.

[0136] For this example, different sizes of filler particles 15 were used.

[0137] When compression occurs due to pressure applied by the bulging of adjacent battery cells (not shown), substrate 7 elongates (left and right arrows) and the width of substrate 7 decreases (up and down arrows). Simultaneously, the cross angle 14b of the fibers with different symbols decreases to 60°.

[0138] and Figure 8a and Figure 8b Unlike in the previous example, the degree of deformation here is additionally controlled by the filler particles 15, because the spacing between the particles 15 is reduced by compression. Once the spacing is reduced to the point where the particles 15 come into contact and thus interlock with each other, further deformation is prevented because the fibers can no longer move relative to each other.

[0139] Figure 10This is a top view of the thermal insulation pad 1 according to the present invention, the thermal insulation pad having parallel ribs 8, a surrounding frame 10 and a gap 11 between the ribs 8 and the surrounding frame 10, wherein the ribs 8 have a structure consisting of interrupted portions 16 extending substantially laterally on the ribs 8.

[0140] These interruptions 16 and outlets 17, 18 are used to exhaust reactive gases, which may form under superheating conditions, particularly through phase change and decomposition of the filler. The resulting gas phase, together with the gas phase formed due to the thermal decomposition of the elastomer, can cause very high gas pressures in the area sealed by the frame 10 between the battery cell wall and the substrate 7. To reduce this pressure, it may be advantageous to integrate the interruptions 16 and outlets 17, 18 as auxiliary venting measures into the thermal insulation pad 1, such as in… Figure 10 As shown in the example.

[0141] Here, the interruption 16 is formed as a continuous structure in the successive ribs 8. Here, the interruption 16 located in the left or right rib next to a rib 8 forms a continuation of the interruption 16 in the rib 8 located therebetween. As a result, a continuous channel for venting gas is obtained. Figure 10 In the specific example shown, these interruptions 16 extend diagonally from the center of the substrate toward the four corners, forming a wide X shape in the overall view.

[0142] In addition, outlets 17 and 18 are provided in the short side of the surrounding frame 8 for exporting the reaction gas from the intermediate space between the battery cell wall and the thermal insulation pad 1.

[0143] The insulating effect and expansion properties of the thermal insulating pad according to the present invention have been studied. The results are as follows: Figures 11 to 14 As shown in the chart.

[0144] To prepare the samples, commercially available two-component liquid silicones with different Shore hardness A, cross-linked at room temperature, were used as silicone elastomers. Table 1 lists the product data and manufacturers.

[0145]

[0146] exist Figure 11 The results of heat transfer measurements on an exemplary battery cell thermal insulation pad are shown. The tests were conducted on a heat transfer measurement platform under a pressure of 1.9 bar to simulate an expansion process. The specimen was made of ELANTAS's SK85L7 silicone elastomer with a Shore A hardness of 45 and an areal density of 163 g / m³. 2Two layers of E-glass fiber fabric were used. The sample dimensions were 235mm × 113.5mm × 2.0mm, consistent with the dimensions of a common prismatic battery. The rib height was 0.4mm, the rib width was 1.0mm, and the rib spacing was 2.0mm.

[0147] To perform the measurement, the sample is first kept at 50°C for 5 minutes to achieve a uniform temperature distribution, during which time the pressure is adjusted.

[0148] Next, heat to 700°C over 200 seconds (without adjusting the pressure). Measure the temperature rise on the front and back sides using a pyrometer.

[0149] The results showed that after the temperature on the front increased from 50°C to 700°C, the temperature on the back remained below 100°C. Therefore, the back temperature was clearly within the range required for practical applications.

[0150] exist Figure 12 and Figure 13 The stress-strain diagram is shown in the spring characteristic curve of a common material sample of the battery cell thermal insulation pad according to the present invention.

[0151] The specimen dimensions are 40mm × 40mm, with a rib height of 0.4mm, a rib width of 2mm, and a total specimen thickness of 2mm. The thickness of the fiber interlayer is between 0.8 and 0.9mm.

[0152] Here, in Figure 12 The figure shows the correlation between spring performance and rib spacing under the same conditions; Figure 13 The diagram illustrates how spring performance varies with the hardness of a silicone elastomer with glass fiber fabric, all other things being equal.

[0153] For according to Figure 12 The experiment used a silicone elastomer ADDV-42 with a Shore hardness A of 45 and an areal density of 25 g / cm³. 2 The sample consists of a fiber interlayer made of E-glass fiber fabric with a flax weave pattern and an orientation of + / -45°.

[0154] for Figure 13 The test results shown in the figure have a uniform rib spacing of 2 mm for the material samples.

[0155] The fiber intermediate layer has an areal density of 80 g / cm³. 2 E-glass fiber fabric with a 0° / 90° orientation and a flax weave.

[0156] Here, all specimens exhibited generally consistent properties up to approximately 40% elongation, with curves 7 and 8 showing the smallest rising slope for specimens made from SK85L7-45 and QSil550 with Shore hardness A of 45 and 55, respectively.

[0157] exist Figure 14 The figure shows the correlation between the deformation properties of specimens with different total thicknesses under preload and full load and the rib spacing. The dimensions of the specimens are related to the above. Figure 12 and Figure 13 The test results showed the same dimensions, but the rib spacing varied.

[0158] For the material structure, the silicone elastomer SK85L7-45 according to Table 1 was used, with two components having an areal density of 80 g / cm³. 2 The fiber interlayer is made of E-glass fiber fabric with a flax weave pattern of + / -45°.

[0159] The initial thickness of each specimen varied from 1.860 mm to 1.530 mm without pressure loading. A pressure of 0.186 N / mm was applied to the specimens. 2 The preload and 1.115 N / mm 2 The maximum surface pressure is measured and the degree of deformation is determined. At this point, the preload strength is equivalent to the commonly used 5kN preload strength. The change in deformation near the target thickness of 1.4mm under preload should be determined, as is typically desired for use with prismatic battery cells.

[0160] At this point, the specimens with a rib spacing of 2 mm and those with a rib spacing of 1.5 mm or 2.5 mm showed the best results, with their preload strength only slightly higher than the expected value of 1.4 mm.

[0161] This invention relates to a thermal insulation pad 1 for insulating adjacent battery cells 2, particularly prismatic battery cells, in a battery system. The thermal insulation pad includes an elastically deformable substrate 7 made of a fiber-elastomer composite structure. A defined number of ribs 8 are provided on two main surfaces of the substrate 7. These ribs extend laterally on the main surfaces of the substrate 7, parallel to each other and spaced apart from each other. The rib arrangement system on the two main surfaces is surrounded by a surrounding frame 10, and there is a gap 11 between the ribs (8) and the frame 10. The fiber-elastomer composite structure of the substrate 7 is formed by an elastomer matrix together with at least one intermediate layer made of mineral fibers embedded therein. The thermal insulation pad is also capable of compensating for the inherent volume changes of the battery cells due to chemical aging of the battery cell components and the periodic expansion and contraction of the battery cells during charging and discharging.

[0162] List of reference numerals

[0163] 1 Insulating mat

[0164] 2 battery cells

[0165] 3 and 4 connecting terminals

[0166] 5 Thermal safety valve

[0167] 6. The bulging main surface of the battery

[0168] 7 substrate

[0169] 8 ribs

[0170] 9. Spacing (between two ribs)

[0171] 10. Surrounding Frame

[0172] 11. Gap (between ribs and frame)

[0173] 12-fiber intermediate layer

[0174] 13 Elastomer Matrix

[0175] 14a, b Intersection Angle

[0176] 15. Filler particles

[0177] 16 Interruption section

[0178] 17, 18. Exports in frame 10.

Claims

1. A thermal insulation pad (1) for insulating adjacent battery cells (2) in a battery system, the thermal insulation pad having an elastically deformable substrate (7) composed of a fiber-elastomer composite structure, a number of ribs (8) provided on two main surfaces of the substrate (7), the ribs extending laterally on the main surfaces of the substrate (7) parallel to each other and spaced apart from each other, the rib arrangement system on the two main surfaces being surrounded by a surrounding frame (10), and a gap (11) between the ribs (8) and the frame (10), the fiber-elastomer composite structure of the substrate (7) being formed of an elastomer matrix together with at least one intermediate layer composed of mineral fibers, the height of the surrounding frame (10) being greater than the height of the ribs (8) under no pressure load, and the deformation resistance of the surrounding frame (10) being greater than the deformation resistance of the ribs (8).

2. The thermal insulation pad (1) according to claim 1, characterized in that, The elastomer material is selected from silicone elastomers, styrene-butadiene rubber, acrylonitrile-butadiene rubber, natural rubber, butyl rubber, isobutylene-isoprene rubber and isoprene rubber, as well as polyurethane.

3. The thermal insulation pad (1) according to claim 2, characterized in that, The elastomer is selected from silicone elastomers and polyurethane.

4. The thermal insulation pad (1) according to claim 1 or 2, characterized in that, The mineral fibers used in the intermediate layer are selected from glass fibers, basalt fibers, silicate fibers, and oxide ceramic fibers.

5. The thermal insulation pad (1) according to claim 1 or 2, characterized in that, The width of the surrounding frame (10) is greater than the width of the rib (8).

6. The thermal insulation pad (1) according to claim 1 or 2, characterized in that, The width of the gap (9) between two adjacent ribs (8) is at least 1.5 to 2 times the width of the rib (8).

7. The thermal insulation pad (1) according to claim 1 or 2, characterized in that, The ribs (8) and the surrounding frame (10) are formed of an elastomeric material.

8. The thermal insulation pad according to claim 7, characterized in that, The rib (8) or the rib (8) and the surrounding frame (10) are formed of the same elastomeric material as the substrate (7).

9. The thermal insulation pad (1) according to claim 1 or 2, characterized in that, The substrate (7) has two or more intermediate layers made of mineral fibers.

10. The thermal insulation pad (1) according to claim 9, characterized in that, An elastomer material is placed between two intermediate layers made of mineral fibers as an adhesive.

11. The thermal insulation pad (1) according to claim 1 or 2, characterized in that, The substrate (7) is provided with a metal foil that reflects infrared radiation.

12. The thermal insulation pad (1) according to claim 1 or 2, characterized in that, The substrate (7), ribs (8) and surrounding frame (10) are integral components.

13. The thermal insulation pad (1) according to claim 1 or 2, characterized in that, The rib (8) has a transversely extending interruption (16) and / or the surrounding frame (10) has at least one outlet for discharging the reaction gas.

14. The thermal insulation pad (1) according to claim 1 or 2, characterized in that, The ribs (8) on the two main surfaces of the substrate (7) are staggered.

15. The use of the thermal insulating pad according to any one of claims 1 to 14 in a battery system having prismatic battery cells.

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