Multifunctional, multi-layer hybrid composite structure

Abstract

A multilayered and multifunctional composite structure comprises a structural reinforcement section configured to provide structural support. This structural reinforcement section includes reinforcing fibers consolidated in a thermoplastic resin. A protective section is located on one side of the structural reinforcement section and configured to provide at least thermal barrier and fire resistance. A shielding section is located on the opposite side of the structural reinforcement section and configured to shield against electromagnetic interference (EMI).

Description

INITIATIONThe information provided in this section is to generally illustrate the context of the disclosure. Work of the present inventors, insofar as described in this section, as well as aspects of the description that may not be prior art at the time of filing, is neither expressly nor silently recognized as prior art over the present disclosure.The present disclosure relates to multifunctional and multilayer hybrid composite structures.Vehicles include structural components such as housings or other structures typically made of metal such as steel or aluminum. In addition to providing structural support functions, the housings may also need to perform other functions, such as thermal insulation, fire resistance, and / or electromagnetic shielding. For example, the structural components may be used in manufacturing a housing for a battery pack or an electric machine. When the structural components are made using aluminum or steel, they may be relatively heavy.SUMMARYA multilayer and multifunctional composite structure includes a structural reinforcement portion configured to provide structural support. The structural reinforcement portion includes reinforcing fibers consolidated in a thermoplastic resin. The thermoplastic resin may be preimpregnated into the reinforcing fibers and / or supplied during compression molding. A protection portion is disposed on one side of the structural reinforcement portion and is configured to provide at least one of thermal barrier and fire resistance. A shielding portion is disposed on an opposite side of the structural reinforcement portion and is configured to shield electromagnetic interference (EMI).In other features, the structural reinforcement portion and at least one of the protection portion and the shield portion are consolidated into the thermoplastic resin in a single step. The structural reinforcing portion, the protecting portion, and the shielding portion are consolidated into the thermoplastic resin in a single step. The protective portion comprises an intumescent material.In other features, the intumescent material includes an adhesive layer configured to attach the intumescent material to the structural reinforcement portion. The protection portion includes a mica plate fixed to the protection portion using a binder. The protection portion includes a fabric, a thermal material, and a refractory material. The protection portion includes a ceramic layer.In other features, at least one of the protection portion and the shielding portion includes a coating. The shield portion is selected from a group consisting of a metal mesh, a discontinuous fabric, a covered veil, a metal sheet, a perforated metal sheet, and a metal covered fiber filled material. The structural reinforcement portion comprises discontinuous fibers selected from a group consisting of cut fibers, unidirectional tape, nonwoven mat, and oriented long fibers. The thermoplastic resin is selected from a group consisting of polyether ether ketone, polyether ketone ketone, polyphenylene sulfide, and polyetherimide.In other features, planar portions of the structural reinforcement portion include continuous fibers and non-planar portions of the structural reinforcement portion include discontinuous fibers.A multilayer and multifunctional composite structure includes a structural reinforcement portion configured to provide structural support and including reinforcing fibers consolidated into a thermoplastic resin. A protection portion is disposed on one side of the structural reinforcement portion and is configured to provide at least one of thermal barrier and fire resistance. A shielding portion is disposed on an opposite side of the structural reinforcement portion and is configured to shield electromagnetic interference (EMI). The structural reinforcing portion and at least one of the protecting portion and the shielding portion are consolidated into the thermoplastic resin in a single step.In other features, the structural reinforcement portion, the protection portion, and the shield portion are consolidated into the thermoplastic resin in a single step. The protecting portion is selected from a group consisting of an intumescent material of one of those consolidated in the thermoplastic resin and attached to the structural reinforcing portion, a mica plate fixed to the protecting portion using a binder, a ceramic layer, and a coating layer. The protection portion includes a fabric, a thermal material, and a refractory material. The shield portion is selected from a group consisting of a metal mesh, a discontinuous fabric, a covered veil, a metal sheet, and a metal covered fiber-filled material.In other features, the structural reinforcement portion comprises discontinuous fibers selected from a group consisting of cut fibers, unidirectional tape, nonwoven mat, and oriented long fibers. The thermoplastic resin is selected from a group consisting of polyether ether ketone, polyether ketone ketone, polyphenylene sulfide, and polyetherimide. Planar portions of the structural reinforcement portion include continuous fibers and non-planar portions of the structural reinforcement portion include discontinuous fibers.Further areas of applicability of the present disclosure will become apparent from the detailed description, claims and drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.BRIEF DESCRIPTION OF THE DRAWINGSThe present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: FIG. 1A is a functional block diagram of an example of a battery cell including anode electrodes, cathode electrodes, and separators; FIG. 1B is a functional block diagram of an example of a battery pack case made of a multifunctional and multilayer thermal composite structure according to the present disclosure; FIG. 1C is a functional block diagram of an example of an electric machine disposed in a housing made of a multifunctional and multilayer thermal composite structure according to the present disclosure; FIGS. 2A to 2C are cross-sectional side views of examples of multifunctional and multilayer thermal composite structures according to the present disclosure; and FIGS. 3-5 are flowcharts of examples of methods for manufacturing the hybrid multilayer and multifunctional composite structures according to the present disclosure.In the drawings, reference numerals may be reused to identify similar and / or identical elements.DETAILED DESCRIPTIONAlthough a multi-layer and multi-functional hybrid composite structure is described below in connection with a structural component or housing for a vehicle, the multi-layer and multi-functional hybrid composite structures may also be used in other applications.The present disclosure relates to a multi-layer and multi-functional hybrid composite structure ("the hybrid composite structure") that provides high strength, reduced heat transfer, and / or electromagnetic interference (EMI) shielding. The hybrid composite structure may be used, for example, to manufacture a housing for a battery pack, an electric machine, or other device to reduce heat transfer and / or EMI into / out of the environment. For example, the hybrid composite structure may be used to prevent thermal runaway propagation (TRP) from one battery cell, module, and / or pack to adjacent battery cells, modules, and / or packs. Housings or other structures made using the hybrid composite structure have fewer parts and a lower mass (e.g., a mass reduction of 40% or more compared to housings or other structures of metal).The hybrid composite structure includes multiple sections or layers that perform different functions and / or include different materials, such as an EMI shielding material, thermal barrier materials, flame retardant materials, reinforcing fibers, and / or resin. In some examples, the hybrid composite structure is consolidated in a single process step, such as by compression molding using a thermoplastic resin. In other examples, the hybrid composite structure is consolidated in one or more process steps.In some examples, surface pretreatment methods may be used to improve adhesion between the functional layers such as the EMI shielding layer, the thermal insulation layer, and / or the refractory layer and other layers of the hybrid composite structure. Examples of surface pretreatment include exposing the material or an adjacent surface to a plasma or flame to heat the surface to improve adhesion to the adjacent layers of the hybrid composite structure.In some examples, an interior portion of the hybrid composite structure includes a resin embedded thermal insulation layer and / or a flame barrier layer. A central portion of the hybrid composite structure includes reinforcing fibers embedded in resin. An outer portion of the hybrid composite structure includes an EMI shielding layer embedded in resin. The outer portion faces the outside environment. In some examples, the hybrid composite structure is made of thermoplastic resin. Thermoplastic resin has a greater potential for recovery and recycling compared to thermosetting resins.The hybrid composite structure is multifunctional in that it provides strength and stiffness, TRP protection, and / or EMI shielding. In some examples, the reinforcement fibers include discontinuous fibers, continuous fibers, and / or a combination thereof in various areas of the hybrid composite structure to adjust the strength and stiffness where needed.Referring now to FIGS. 1A through 1C, various examples of housings incorporating the hybrid composite structure are illustrated. In FIG. 1A, an example of a battery cell is shown. In FIG. 1B, a housing for a battery pack including the hybrid composite structure includes a plurality of battery modules (each including a housing and a plurality of battery cells of FIG. 1A ). In FIG. 1C, an electric machine is disposed in a housing that includes the hybrid composite structure. The housings for the battery module, the battery pack, and / or the electric machine may include a body and / or a cover that provide a hermetic seal. The body and / or cover may be manufactured using the hybrid composite structures described below.For example, if the battery cells in one or more battery modules or the battery pack fail, a thermal breakdown event may occur. Thermal breakdown events are caused as the temperature of the battery cells, the battery module, and / or the battery pack increases. The increased temperature releases energy from the battery cells, which further increases the temperature of the battery and / or the adjacent structures. If not erased, a thermal breakdown event occurs between the battery cells, the battery module, and / or the battery pack, which may increase the temperature of other adjacent battery modules / packs. The elevated temperature increases the likelihood of further thermal runaway propagation (TRP) events).Referring now to FIG. 1A, a battery cell 10 includes C cathode electrodes 20, A anode electrodes 40, and S separators 32 arranged in a predetermined order in a stack 12 in a battery cell case 50. The cathode electrodes 20-1, 20-2,..., and 20-C (where C is an integer greater than one) include cathode active layers 24 disposed on one or both sides of the cathode current collectors 26. The anode electrodes 40-1, 40-2,..., and 40-A (where C is an integer greater than one) include anode active layers 42 disposed on one or both sides of the anode current collectors 46.In some examples, the anode active layers 42 and / or the cathode active layers 24 comprise coatings comprising one or more active materials, one or more conductive fillers / additives, and / or one or more binders. In some examples, the battery cells and / or electrodes are prepared by applying a slurry to coat the current collectors in a roll-to-roll process. In some examples, the cathode current collectors 26 and the anode current collectors 46 comprise foil layers. In some examples, the current collectors are made of one or more materials selected from a group consisting of copper, stainless steel, brass, bronze, zinc, aluminum, and alloys thereof. Outer tabs 28 and 48 allow external connection to the current collectors and may be located on the same side, on opposite sides, or on different sides.In FIG. 1B, a battery pack 90 includes a battery pack housing 92 enclosing a plurality of battery modules 80- 1, 80- 2,..., and 80-M, M being an integer greater than one. The battery pack case 92 includes a cover 93 and a lower body or shell 95. each of the battery modules 80 includes a battery module case 82 and a plurality of battery cell cases 50- 1, 50- 2,..., 50- C disposed in the battery module case 82. In some examples, the battery module housing 82 and / or the battery pack housing 92 is manufactured using the hybrid composite structure.In FIG. 1C, an electric machine 96 is disposed in a housing 98. In some examples, the housing 98 for the electric machine 96 is manufactured using the hybrid composite structure. In some examples, the housing 98 may include a lid 97 and a body 99.Referring now to FIGS. 2A through 2C, examples of hybrid composite structures are illustrated. In FIG. 2A, a hybrid multilayer composite structure 150 includes an inner surface 152 facing the device (e.g., the battery, the electric machine, etc.) and an outer surface 154. The hybrid composite structure 150 includes a heat shield portion 160 configured to provide heat protection and / or fire resistance, a structural reinforcement portion 164 configured to provide structural support for the housing, and a shielding portion 168 configured to shield EMI.In some examples, the reinforcement portion 164 is consolidated and then the thermal shield portion 160 and the shield portion 168 are secured using adhesive and / or a surface finish such as heating with plasma or a flame. In some examples, the thermal protection portion 160 is consolidated with the reinforcement portion 164 in the same consolidation step. In some examples, the reinforcement portion 164 is consolidated with the shield portion 168 in the same consolidation step. In some examples, the thermal protection portion 160, the reinforcement portion 164, and the shield portion 168 are consolidated in the same consolidation step. In other examples, the reinforcement portion 164 is preconsolidated and one or more additional consolidation steps are performed.The thermal protection portion 160 includes one or more layers 180 embedded in resin 184. The thermoplastic resin may be preimpregnated into the reinforcing fibers and / or supplied during compression molding. In some examples, the one or more layers 180 of the thermal protection portion 160 comprise an intumescent material. Examples of fire retardant materials are fabrics impregnated with fire retardants such as aluminum tetrahydrate (ATH) and / or ammonium polyphosphate (APP). Additional examples of fire retardant materials include kaolin, sodium silicate, aluminum hydroxide, magnesium hydroxide, hydrated silica, silicone, titanium dioxide, and compounds based on phosphorus, nitrogen, antimony, boron, zinc, or halogens such as bromine and chlorine. A combination of these materials may also be used. In some examples, the protection portion 160 includes a ceramic material embedded in the resin. In some examples, the protection portion 160 comprises a rigid plate of mica.An example of an intumescent material is expandable graphite (EG). Additional examples of intumescent materials include a combination of materials for creating an insulating carbon, including an acid source, a carbon source, and a propellant. Acid sources aid in initiating the intumescent reaction and may include phosphates which release phosphoric acid upon heating, such as ammonium polyphosphate, melamine phosphate and guanyl urea phosphate, which could also serve as a carbon source. Compounds that release other acids, such as boric acid, and acidic polymers, could also serve as acid sources. Carbon sources provide a carbonaceous char layer and may comprise expandable graphite, a polyol such as pentaerythritol and sorbitol, and a carbohydrate such as starch, cellulose and dextrin. Propellants release gas upon heating, causing the intumescent material to form the expanded charcoal layer, and may include ammonium polyphosphate, melamine, ammonium bicarbonate, sodium bicarbonate, urea, and azodicarbonamide. Upon heating above a certain temperature, the intumescent material expands and forms a protective carbonizing which acts as a barrier to fire. In some examples, the predetermined temperature corresponds to a temperature occurring during a thermal runaway event.In some examples, the one or more layers 180 comprise a flexible fabric reinforced with thermal material and / or a flame retardant layer. In some examples, the thermal material and / or flame barrier layer will only minimally or not expand when exposed to high heat or flames. Examples include materials that undergo pyrolysis and form a carbonaceous char or insulating layer. Examples include cement-based materials, clay, calcium silicate, silica, alumina, zirconia, gypsum, and ceramics.In some examples, the heat protection portion 160 includes a material that absorbs heat through endothermic reactions. Examples of these materials include ammonium phosphate, hydrated compounds such as aluminum and magnesium hydrates, ammonium sulfate, melamine cyanurate, some phosphorus compounds and potassium carbonate. In some examples, the thermal protection portion 160 maintains the electrical isolation properties when exposed to flames. Examples of these materials include silicone-based compounds, phenolic resins, mineral-based compounds, and ceramics.In some examples, the reinforcement layer 164 comprises reinforcement fibers 186 including continuous fibers, discontinuous fibers, and / or a mixture of continuous and discontinuous fibers. Suitable reinforcing fibers include carbon fibers (e.g., carbon black, carbon nanotubes, talc, polyacrylonitrile fibers, cellulose precursors, and / or pitch precursors), glass fibers (e.g., glass fiber, quartz), basalt fibers, aramid fibers, and combinations thereof. In some examples, the continuous fibers are disposed in planar portions of the structure and / or the discontinuous fibers are disposed in non-planar or irregular portions of the structure.In some examples, the EMI shielding layer 188 comprises a woven metal mesh, a continuous or discontinuous flexible fabric, a covered veil, a metal sheet, a perforated metal sheet, or a metal covered fiber filled material. The EMI shielding layer may include, for example, only aluminum foil, copper mesh, nickel mesh, carbon fibers electrolytically coated with copper and nickel.In FIG. 2B, the reinforcement portion 164 is consolidated and then the thermal protection portion 160 is secured using adhesive (and / or face treatment) or consolidated in a second consolidation step. The shield portion 168 is also secured using adhesive (and / or face treatment) or consolidated in the second or subsequent consolidation step on the other side of the reinforcement portion 164.For example, one or more layers 192 of the thermal protection portion 160 are attached to one side of the reinforcement portion 164 by an adhesive layer 193. In some examples, the one or more layers 192 include a thermally insulating layer and / or a flame retardant layer. In some examples, the reinforcement layer 164 includes reinforcement fibers 186. In some examples, the reinforcement fibers 186 include continuous fibers, discontinuous fibers, and / or a mixture of continuous and discontinuous fibers. The shielding layer 168 includes an electromagnetic interference (EMI) shielding layer 193 secured to the reinforcing portion 164 by adhesive 194 (and / or face treatment).In FIG. 2C, the thermal protection portion 160 includes a protection layer 196 coated on an exposed surface of the reinforcement portion 164. In some examples, the protective coating layer 196 is applied in liquid form by spray coating, dip coating, flow coating, and / or other suitable coating methods. In some examples, the coatings include fire retardant compounds such as those previously described as fire retardant intumescent materials, hydrated materials and ceramics, as well as binders, solvents and other additives used in coatings. In some examples, the protective coating layer 196 is cured using thermal, UV radiation, moisture, and / or chemical reactions at room temperature (or other temperature) when reactants are combined.In some examples, the EMI shielding layer 188 includes a coating layer 198 that is applied in liquid form and optionally cured as described above. In some examples, the EMI shielding layer includes a coating including conductive particles (e.g., copper, aluminum, silver, nickel, gold, tin, or graphene). In other examples, the shielding layer is deposited using a metallization process.In some examples, the hybrid composite structure is capable of withstanding a flame of 950° C. for 5 minutes while limiting the temperature on the opposite side of the hybrid composite structure to a temperature of less than 370° C.In some examples, the hybrid composite structure comprises discontinuous carbon fibers in a thermoplastic polymer matrix. In some examples, the discontinuous carbon fiber comprises a unidirectional ribbon, a nonwoven mat, and / or directed long fiber technologies used in compression molding or embossing. In some examples, the hybrid composite structure comprises chopped carbon fiber fillers and a polymer matrix comprising a thermoplastic polymer selected from a group consisting of polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyphenylene sulfide (PPS), polyetherimide (PEI), and combinations thereof.In some examples, the hybrid composite structure includes continuous fibers in flat regions and discontinuous fibers in regions having non-planar geometric features, such as a channel, ribs, reinforcements, and / or hat portions. In some examples, the hybrid composite structure is produced in a single consolidation step using a compression molding process.Referring now to FIGS. 3-5, examples of methods 250, 300, and 400 for making the hybrid composite structure and / or housings incorporating the hybrid composite structure are illustrated. In FIG. 3, the method 250 includes arranging the protective layer(s), the reinforcement fibers, and the shielding layer in a stack at 260. At 264, the stack is impregnated with resin (e.g., thermoplastic resin) and consolidated into a multi-layered and multi-function hybrid composite structure using pressure and / or heat in a single step. At 268, a package or other structure is manufactured using the hybrid multilayer composite structure.In FIG. 4, the method 300 includes arranging reinforcement fibers in a pattern at 310. At 314, the reinforcement fibers are impregnated with resin (e.g., thermoplastic resin) and consolidated using pressure and / or heat to form the reinforcement portion. At 318, the heat / fire protection portion and the EMI shielding portion are attached or consolidated to opposing sides of the reinforcement portion to produce a multi-layer and multi-function hybrid composite structure. At 322, a package or other structure is manufactured using the hybrid multilayer composite structure.In FIG. 5, the method 400 includes arranging reinforcement fibers in a pattern at 410. At 414, the reinforcement resin and the heat / fire protection portion or the shield portion are impregnated with resin (e.g., thermoplastic resin) and consolidated using pressure and / or heat to form a consolidated core. At 418, the other of the heat / fire protection portion or the EMI shielding portion is attached or consolidated to the consolidated core to produce a multi-layer and multi-function hybrid composite structure. At 422, a package or other structure is manufactured using the hybrid multilayer composite structure.The foregoing description is for illustrative purposes only and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure may be practiced in a wide variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be limited to the same as other changes will become apparent after studying the drawings, the specification, and the following claims. It should be appreciated that one or more steps within a method may be performed in different order (or simultaneously) without altering the principles of the present disclosure. Further, although the embodiments are each described above as being provided with certain features, any one or more of those features described with respect to one embodiment of the disclosure may be implemented with and / or combined with features of any of the other embodiments, even if that combination is not expressly described. In other words, the described embodiments are not mutually exclusive, and an exchange of one or more embodiments with each other remains within the scope of this disclosure.Spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.) are described with various terms including "connected," "engaged," "coupled," "adjacent," "next," "top-on," "over," "under," and "arranged.". Unless a relationship between first and second elements is expressly described as "direct" in the foregoing disclosure, this relationship may be a direct relationship in which no other intervening elements are present between the first and second elements, but also an indirect relationship in which one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the term "A, B, and / or C" should be construed as being logical (A ORed with B ORed with C) using a non-exclusive logical OR operation and should not be understood as "at least one of A, at least one of B, and at least one of C.".In the figures, the direction of an arrow as indicated by the arrow head generally illustrates the flow of information (such as data or instructions) of interest for the illustration. For example, if element A and element B exchange a plurality of information, but the information sent from element A to element B is relevant for illustration, the arrow may point from element A to element B. This unidirectional arrow does not mean that no other information is sent from element B to element A. Further, for information sent from element A to element B, element B may send requests or acknowledgements for the information to element A.

Claims

A multilayer and multifunctional composite structure comprising: a structural reinforcement portion configured to provide structural support and comprising reinforcing fibers consolidated in a thermoplastic resin; a protection portion disposed on one side of the structural reinforcement portion and configured to provide at least one of thermal barrier and fire resistance; and a shielding portion disposed on an opposite side of the structural reinforcement portion and configured to shield electromagnetic interference (EMI).The multilayer and multifunctional composite structure of claim 1, wherein the structural reinforcement portion and at least one of the protection portion and the shielding portion are consolidated into the thermoplastic resin in a single step.The multilayer and multifunctional composite structure of claim 1, wherein the structural reinforcement portion, the protection portion, and the shield portion are consolidated into the thermoplastic resin in a single step.The multilayer and multifunctional composite structure of claim 1, wherein the protective portion comprises an intumescent material.The multilayer and multifunctional composite structure of claim 4, wherein the intumescent material comprises an adhesive layer configured to attach the intumescent material to the structural reinforcement portion.The multilayer and multifunctional composite structure of claim 1, wherein the protective portion comprises a mica plate attached to the protective portion using a binder.The multilayer and multifunctional composite structure of claim 1, wherein the protective portion comprises a fabric, a thermal material, and a fire resistant material.The multilayer and multifunctional composite structure of claim 1, wherein the protective portion comprises a ceramic layer.The multilayer and multifunctional composite structure of claim 1, wherein at least one of the protection portion and the shield portion comprises a coating.The multilayer and multifunctional composite structure of claim 1, wherein the shield portion is selected from a group consisting of a metal mesh, a discontinuous fabric, a coated veil, a metal sheet, a perforated metal sheet, and a metal coated fiber-filled material.

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