Thermoplastic battery cover reinforced with continuous fiber composite sheet to control bursting pressure

Abstract

Embodiments of the present invention include a cover for a battery pack of an electric vehicle including a plastic sheet defining an edge periphery dimensioned to cover an opening of a housing subassembly of the battery pack, the plastic sheet including a plurality of cover fastening features proximate the edge periphery, the fastening feature defines a cap fastening periphery. The embodiments include a continuous fiber reinforced composite sheet preform coupled to the plastic sheet defining a boundary region of the plastic sheet around the continuous fiber reinforced composite sheet preform such that the continuous fiber reinforced composite sheet preform is spaced from the cover fastening periphery.

Description

Technical Field

[0001] The subject matter of the present invention relates to multi-cell battery packs, and more particularly to a thermoplastic battery cover reinforced with continuous fiber composite sheets to control burst pressure. Background Art

[0002] Many covers for electric vehicle battery packs are made of steel, aluminum, or thermosetting materials such as sheet molding compound (SMC). While these solutions provide good mechanical property retention over a wide temperature range and can subsequently withstand high-pressure loads from inside the battery pack during thermal runaway, they also have to rely on additional thermal barriers to ensure that the temperature on the non-exposed side of the cover is kept within certain limits to ensure the safety of the occupants in the vehicle. Another challenge with these solutions is that it is challenging to conceive structural ribs and features due to inherent manufacturing limitations.

[0003] Plastics offer high potential for constructing battery pack components. For example, they are lighter than metals, which can reduce energy consumption due to vehicle movement stop / start. In addition, some plastics offer charring (i.e., the ability to form a black carbon layer similar to wood), which can increase their resistance to destruction under thermal anomalies. Moreover, many features can be molded into plastic parts, thereby reducing battery pack costs.

[0004] While plastics offer these advantages, they also have some disadvantages compared to metals. One disadvantage is that plastics may soften when they heat up. If the battery pack cover is intended to contain combustion gases, this softening may lead to an undesired expansion of the battery pack. Solutions are needed that utilize the inherent potential of thermoplastics while managing their performance under thermal anomalies.

[0005] US8835033B2 discloses a battery pack that uses a plastic housing to support the weight of the battery pack, where a composite material extends to the brackets.

[0006] JP2012018797A discloses a housing having a frame formed of ribs including reinforcing fibers to increase the load-bearing capacity of the housing.

[0007] DE102017217155A1 discloses a battery housing having cell partitions formed of a plastic material reinforced with continuous fibers to hold the cells in place in the housing.

[0008] WO2020200885A1 discloses a battery pack housing formed of a thermosetting plastic reinforced with continuous fibers. Summary of the Invention

[0009] To address the above deficiencies, the present disclosure recognizes that introducing patches of continuous fiber sheets to the lid changes its characteristics upon inflation, similar to applying tape to a balloon. By fixing the patch to the lid, the inflation characteristics can be controlled within desired limits in a simple and low-cost manner that is feasible for manufacturing. The patch can be circular, rectangular, or in the form of strips, as described herein.

[0010] The present disclosure also provides reinforcing structural ribs that enhance stiffness, such that the resulting hybrid lid solution is robust enough to provide the desired bending performance while withstanding relatively high pressures and high temperatures in the event of a thermal runaway within the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The following drawings are shown by way of example and not limitation. For brevity and clarity, not every feature of a given structure is always labeled in every drawing in which that structure appears. Identical reference numerals do not necessarily denote identical structures. Instead, identical reference numerals may be used to indicate similar features or features having similar functions, and different reference numerals may as well.

[0012] Figure 1A Perspective view of a lid including multiple sheet patches according to various examples.

[0013] Figure 1B For Figure 1A Front view of the lid shown in

[0014] Figure 2 Schematic diagram of a battery pack.

[0015] Figure 3A Perspective view of the top of a battery lid without reinforcement.

[0016] Figure 3B For Figure 3B Bottom perspective view of the lid of

[0017] Figure 4A Perspective view of the top of a fully reinforced battery lid.

[0018] Figure 4B For Figure 4B Bottom perspective view of the lid of

[0019] Figure 5A Perspective view of the top of a partially reinforced battery lid.

[0020] Figure 5B For Figure 5B Bottom perspective view of the lid of

[0021] Figure 6A Perspective view of the top of a partially reinforced battery lid.

[0022] Figure 6B Perspective view of the bottom of the cover for Figure 6B .

[0023] Figure 7 Perspective view of the bottom of a partially reinforced battery cover, showing ribs molded onto the reinforcement.

[0024] Figure 8A Showing Figure 3A the deformation of the cover of -B at 38 kPa pressure.

[0025] Figure 8B Showing the Figure 8A cover at 50 kPa pressure.

[0026] Figure 8C Showing Figure 8A the degradation of the stiffness of the cover of at 38 kPa pressure.

[0027] Figure 8C.1 Perspective view of the part marked Figure 8C in Figure 8C.1 .

[0028] Figure 8D Showing the Figure 8A cover at 50 kPa pressure.

[0029] Figure 9A Showing Figure 4A the deformation of the cover of -B at 38 kPa pressure.

[0030] Figure 9B Showing the Figure 9A cover at 50 kPa pressure.

[0031] Figure 9C Showing Figure 9A the degradation of the stiffness of the cover of at 38 kPa pressure.

[0032] Figure 9D Showing Figure 9A the degradation of the stiffness of the cover of at 50 kPa pressure.

[0033] Figure 9D.1 Perspective view of the part marked Figure 9D in Figure 9D.1 .

[0034] Figure 10A Showing Figure 5A the deformation of the cover of -B at 38 kPa pressure.

[0035] Figure 10B Showing the Figure 10A cover at 50 kPa pressure.

[0036] Figure 10C shows the degradation of the stiffness of the lid of Figure 10A under a pressure of 38 kPa.

[0037] Figure 10D shows the Figure 10A degradation of the stiffness of the lid of

[0038] Figure 10D.1 is a close-up of the part marked as Figure 10D in Figure 10D.1

[0039] Figure 11A shows the Figure 6A deformation of the lid of

[0040] Figure 11B shows the Figure 11A lid of

[0041] Figure 11C shows the Figure 11A degradation of the stiffness of the lid of

[0042] Figure 11D shows the Figure 11A degradation of the stiffness of the lid of

[0043] Figure 11D.1 is a close-up of the part marked as Figure 11D in Figure 11D.1

[0044] Figure 12A shows the Figure 7 deformation of the lid of

[0045] Figure 12B shows the Figure 12A lid of

[0046] Figure 12C shows the Figure 12A degradation of the stiffness of the lid of

[0047] Figure 12C.1 is a close-up of the part marked as Figure 12C in Figure 12C.1

[0048] Figure 12D shows the Figure 12A degradation of the stiffness of the lid of

[0049] Figure 12D.1 is a close-up of the part marked as Figure 12D in Figure 12D.1 ​​​A close-up of the part. DETAILED DESCRIPTION

[0050] One challenge in bringing a plastic battery housing cover to market is the large size of the component. Injection molding is well-suited for small components, but large components such as the cover of a battery pack are difficult to manufacture and require special tools. This can be addressed using modern manufacturing techniques such as injection-compression molding, thermoforming, rotational molding, etc., but challenges still remain. For example, for the top cover, there are typically relatively low requirements for structural integrity because the cover supports little weight - mainly its own weight. Therefore, in order to enjoy the benefits of lightweighting, the cover should be relatively thin. However, in some battery pack designs, there is a need to restrain backpressure / burst pressure and / or sag, such as during a thermal anomaly, or even during various changes in climate, pressure, etc. There are also other needs, such as the need to tune the battery pack to have certain noise characteristics. One way to address these needs lies in manufacturing a cover composite material reinforced with continuous fibers. However, this presents other challenges. Composite materials are known to be difficult to manufacture because the fibers are much less ductile than the matrix material (e.g., thermoplastic) in which they are placed. For example, forming a sheet of fiber reinforcement into a non-planar part may result in wrinkling at the corners.

[0051] To address these challenges, the present inventors have used composite materials in a specific manner. By setting composite segments or "patches" into the cover, it has been found that the expansion of the cover can be controlled within desired limits, such that the battery pack can maintain pressure and control burst pressure and / or sag. Resisting burst below a threshold or resisting sag can reduce the rate at which a thermal anomaly propagates through the battery pack, such as by restricting the entry of oxygen from the atmosphere or providing a controlled burst event. It can also protect the rest of the vehicle from the effects of a thermal anomaly, such as by retaining the ability to form carbon, which can resist heat transfer. Additional benefits include the ability to tune the deformation characteristics of the cover and even tune the cover to provide desired vibration behavior.

[0052] An object of the present subject matter is to provide a thermoplastic hybrid battery cover solution having a locally or globally reinforcing continuous fiber composite laminate along an outer or inner surface of the thermoplastic solution. An object is to provide a thermoplastic cover having integrated structural ribs inside or outside the cover based on the available packaging space in the vehicle and battery pack architecture. An object is to provide a hybrid thermoplastic solution by common manufacturing methods such as injection molding, compression molding, and thermoforming. Several exemplary combinations are shown.

[0053] Figure 1A -B shows a simplified example of the present subject matter. A cover 102 for a battery pack 100 for an electric vehicle is shown. The battery pack may employ Figure 2The form shown in. The cover 102 can be a top cover. The cover 102 can include a plastic sheet 104. The cover 102 can include a reinforcing sheet 106 coupled to the plastic sheet 104. The plastic sheet 102 can be bonded or fused to the reinforcing sheet 106. The reinforcing sheet 106 can include a preform. The reinforcing sheet 106 can be insert molded into the cover 102 or otherwise fused to the plastic sheet 104 in a molding operation, such as an injection molding operation. The reinforcing sheet 106 can be laminated to the plastic sheet 104. The reinforcing sheet 106 can be adhered to the plastic sheet 104. The sheets can be fused by any suitable means, such as an adhesive, or one of vibration welding, ultrasonic welding, infrared (IR) welding, hot plate welding, laser welding, and thermal welding. The reinforcing sheet 106 can be integrally formed during the molding of the lower cover 102. The reinforcing sheet 106 can be cut to the appropriate size as needed and then can be disposed on the bottom of the cover 102 in a single layer or in multiple layers. The reinforcing sheet 106 can be buried in the cover 102 or can be attached to the surface. The reinforcing sheet 106 can be disposed on the upper surface (outer surface), lower surface, or both the upper and lower surfaces of the cover 102. To install the reinforcing sheet 106, the reinforcing sheet 106 can be cut to the appropriate size. The reinforcing sheet 106 can be stacked in a single layer or in multiple layers and preheated. The reinforcing sheet 106 can be placed or installed at a desired location in the mold of the cover 102. The cover 102 can be molded by an extrusion-compression molding device or the like. When a high-temperature fiber-reinforced composite material transferred as the material of the cover 102 is disposed in a mold for extrusion molding, the cover 102 can be integrally formed with the reinforcing sheet 106 without a separate subsequent process.

[0054] As further discussed herein, the reinforcing sheet 106 can be a continuously fiber-reinforced composite sheet. The reinforcing sheet 106 can include a preform. The reinforcing sheet 106 can be a patch. Although three reinforcing sheets 106 are shown, there can be as few as one or more than three. Additionally, although the three reinforcing sheets 106 are shown as having a quadrilateral shape with an upper major surface 108 and a lower major surface 110 opposite the upper major surface 108, other shapes, such as oval, strip, etc., can be used. The reinforcing sheet 106 can span less than the entire plastic sheet 104.

[0055] The plastic sheet can define an edge perimeter 112. The size of the edge perimeter 112 can be set to cover an opening of a housing subassembly of a battery pack (see, for example Figure 2The opening 202). The plastic sheet 104 may include one or more fastening features 114. One or more fastening features 114 may be adjacent to the edge periphery 112 and may define a cover fastening periphery 116. The boundary regions D1 and / or D2 of the plastic sheet 104 may be defined between one or both of the edge periphery 112 and the fastening periphery 116 and the reinforcing sheet 106. The boundary region of the plastic sheet 102 may surround the reinforcing sheet 106. The reinforcing sheet 106 may be spaced apart from the edge periphery 112. The fastening features may include eyelets overmolded by the plastic sheet. The eyelets may be formed of metal.

[0056] Figure 2 is a schematic diagram of a battery pack. The battery pack may include a subassembly housing 206. One or more battery cells 204 may be disposed in the subassembly housing. The cover 102 may cover the opening 202 in the housing subassembly 206. The cover 102 may cover the battery cells 204 disposed in the housing subassembly. The battery cells of the battery pack may be arranged in a cluster defining a plane 214. Referring to FIG. 1, the size of the cover 102 may be set to substantially cover the plane 102, the cover 102 having a proximal portion 220 and a distal portion 222, the size of the cover 102 being set such that the distance between the proximal portion 220 and the distal portion 222 may be set to extend from a first position 224 proximate a first edge 226 of the plane 214, through the plane 214, to a second position 228 proximate a second edge 230 of the plane 214, the second edge 230 being opposite the first edge 226 of the plane 214.

[0057] The top cover may have a bending stress lower than that of the housing subassembly 206. The bending stress may be measured across an axis bisecting the subassembly. In one example, the bending stress may be measured across an axis that may pass through the center of gravity of the component or above / below the center of gravity of the assembly. An optional additional cover 208 may be used, such as for noise control or an additional thermal barrier. The optional additional cover 208 may be metallic. The battery pack may be fitted into a vehicle part 210, such as a floor, and the battery pack may be adjacent to or near the floor. A schematic of pressure 212 and a thermal anomaly 214 are depicted. The pressure may be positive or negative relative to the ambient pressure of the package, although it is shown as positive. The cover 102 may be an anisotropic expansion cover, which means that when it expands, different parts expand at different expansion rates.

[0058] As discussed above, the cover 102 may include a sheet, such as a reinforcing sheet, also referred to as a lamina. The reinforcing sheet 106 may be coupled to the interior of the cover. The reinforcing sheet 106 may be coupled to the exterior of the cover. The span of the reinforcing sheet 106 is less than the entire plastic sheet 104. The reinforcing sheet 106 may be framed by the plastic sheet 104.

[0059] Such thin sheets may include, but do not necessarily include, fibers. If included, the fibers may include fibers having one or more of the compositions of the present invention (e.g., made by passing the molten or dissolved (one or more) compositions through a spinneret), carbon fibers, glass fibers, aramid fibers, ceramic fibers, basalt fibers, volcanic ash fibers, natural fibers, and / or the like. In some such thin sheets, the fibers may be dispersed within a matrix material that includes, for example, one or more of the compositions of the present invention, a thermoplastic material, and / or a thermosetting material.

[0060] The fibers in such thin sheets may be arranged in any suitable manner. By way of illustration, the fibers may be aligned in a single direction. For example, the thin sheet may be unidirectional (e.g., a unidirectional tape). The fibers may be arranged in a woven configuration, such as in a plain weave, twill weave, satin weave, basket weave, leno weave, mock leno weave, or similar weave. The thin sheet may be non-woven (e.g., dry laid, wet laid, spunbonded, etc.), where the fibers are multi-directional, arranged in a sheet or web, and joined to each other by entanglement and / or heat and / or chemical bonding rather than by weaving or knitting. The unidirectional tape may have an arrangement (strand arrangement) in which many strands of continuous fibers extend longitudinally in the same direction, and the continuous fiber fabric may have a woven structure in which the continuous fibers cross each other longitudinally and transversely. Unidirectional (UD) or woven types of continuous fibers may be used. Some examples of the woven type may include plain weave, twill weave, and satin weave types woven at 0° / 90° and types woven at 0° / 90° / -45° / 45°. When using a reinforced thin sheet in which the continuous fibers are arranged in one direction (e.g., using a unidirectional tape as the fiber reinforcement material), the continuous fibers in the reinforced thin sheet may be arranged in the "cross direction" with respect to the front-to-back longitudinal direction of the lid (i.e., the continuous fibers in the reinforced thin sheet may be arranged in the left-to-right width direction with respect to the front-to-back longitudinal direction of the lid).

[0061] The lid 102 and the reinforced thin sheet 106 may be made using the unidirectional tape or continuous fiber fabric described above. Thus, the lid 102 and the reinforced thin sheet 106 may be made such that the continuous fibers in the plastic matrix may be arranged in one direction or fixed in the form of woven fibers.

[0062] As described, some thin sheets containing one or more of the compositions of the present invention may not include fibers; for example, such thin sheets may include sheets or films of (one or more) of those compositions. Laminates are also disclosed, which may include any two or more of the thin sheets described above arranged in any suitable laminating manner (e.g., asymmetric or symmetric).

[0063] The compositions of the present invention can also be incorporated into skin-core (e.g., sandwich structures, ABA, etc.) composite materials, where the (one or more) skins, which are relatively thin and stiff compared to the core, are disposed on one or both sides of a core that is relatively thick and low density compared to the (one or more) skins. By way of example, the core can include foams (e.g., open-cell or closed-cell), honeycomb structures, balsa wood, and / or the like, and the (one or more) skins can include (one or more) fiber-reinforced laminates. Such skin-core composite materials can contain one or more compositions of the present invention because their (one or more) skins can include one or more of any of the above-mentioned sheets and laminates and / or their cores can contain one or more compositions of the present invention.

[0064] Molding materials comprising one or more compositions of the present invention can be used and are suitable for, e.g., injection molding and / or compression molding. Such molding materials can be provided as pellets. The disclosed molding materials can include fillers such as talc, calcium carbonate, discontinuous or short fibers (e.g., including any of the above fiber types), and / or the like.

[0065] The compositions of the present invention can be incorporated into articles. By way of illustration, such articles can include one or more of any of the above-mentioned sheets, laminates, and skin-core composite materials and / or any of the above-mentioned molding materials. In such articles comprising one or more sheets, one or more laminates, and / or skin-core composite materials, the (one or more) sheets, the (one or more) laminates, and / or the (one or more) skin-core composite materials can be joined to the molding material via overmolding, compression molding, and / or the like. The compositions of the present invention can have a high enough RF transparency such that they are particularly suitable for articles where RF transparency is desired.

[0066] The cover can be manufactured by an extrusion-compression molding method using a fiber-reinforced plastic composite material to reduce weight. Long fibers or continuous fibers having an aspect ratio (i.e., length divided by diameter (L / D)) of about 1,000 or greater (i.e., fibers where there are no breaks) can be used to improve the structural stiffness, crash characteristics, and dimensional stability of the housing.

[0067] When a fiber-reinforced thermoplastic composite material containing reinforcing fibers is compression molded into the cover 102, the cover 102 can be formed such that the length of the remaining or residual reinforcing fibers is such that they at least on average provide fibers having an aspect ratio of about 1,000 or greater. When the aspect ratio of the remaining or residual reinforcing fibers is less than about 1,000, sufficient stiffness enhancement may not be achieved. The aspect ratio of the remaining reinforcing fibers can be in the range of about 1,000 to about 10,000.

[0068] Generally, the dimensional stability of a component may be directly affected by the shape of the component, but can be improved by appropriately selecting materials and forming methods. Thus, according to various embodiments, a fiber-reinforced plastic composite housing can be manufactured by an extrusion-compression molding method, which can minimize residual stresses caused by shear forces during product molding.

[0069] According to various embodiments, when manufacturing the cover 102, the long fibers may account for about 30 wt% to about 70 wt% of the total weight of the plastic composite material used to form the cover 102. When the weight of the long fibers is less than about 30 wt%, the desired mechanical properties may not be achieved. On the other hand, when the weight of the long fibers is greater than about 70 wt%, the fluidity may be reduced during molding, resulting in a decrease in moldability and deterioration of the appearance quality.

[0070] When manufacturing the fiber-reinforced plastic composite cover 102, long fibers and continuous fibers can be blended and used as reinforcing fibers. In particular, reinforcing fibers of the continuous fiber type can be blended with the long fibers. The continuous fibers can be applied to the entire area of the cover 102 (i.e., throughout the cover 102). The continuous fibers can be applied only locally to one or more parts that require high stiffness. The continuous fibers can be applied only partially to the part of the cover 102 configured with typical structural reinforcement members, such as cross members, side members, and mounting brackets), or only partially to the part of the cover 102 that is connected to the vehicle body by bolts or the like. When the continuous fibers are applied locally, the typical structural reinforcement members can be integrally formed with the outer shell of the continuous fibers.

[0071] Thus, the reinforcing sheet 106 can be a continuous fiber-reinforced composite sheet connected to the plastic sheet. The reinforcing sheet 106 can be formed of a unidirectional tape. The unidirectional tape can include continuous fibers disposed in a thermoplastic matrix. The unidirectional tape can include continuously arranged parallel fibers. The reinforcing sheet 106 can be formed of a fabric. The cover 102 can include a plastic sheet 102. The plastic sheet can be formed of a solid thermoplastic. The plastic sheet 104 can be formed of a short chopped strand glass fiber-reinforced thermoplastic having a matrix material. The short chopped strand glass fiber can be formed of a resin matrix of glass fibers having a certain size. The glass fibers can be 10 mm or less, 8 mm or less, 3 mm or less, or even shorter. The matrix material of any of the housing sub-assemblies or sheets can be formed of various materials. The plastic matrices of these components can be the same or different from each other. When the same plastic matrix is used, the interfacial bonding strength between different types of components can be improved.

[0072] The substrate material can be formed from a polymer composition comprising a thermoplastic polymer. The thermoplastic polymer is not particularly limited and can include at least one of the following: polyacetal, polyacrylic, polycarbonate, polystyrene, polyester, polyamide, polyamideimide, polyarylate, polyarylsulfone, polyethersulfone, polyphenylene sulfide, polysulfone, polyimide, polyetherimide, fluorine-containing polymers (e.g., polytetrafluoroethylene), polyether ketone, polyether ether ketone, polyether ketone ketone, polybenzoxazole, polyoxadiazole, polybenzimidazole, polyacetal, polyanhydride, poly(vinyl ether), poly(vinyl sulfide), poly(vinyl alcohol), poly(vinyl ketone), poly(halogenated vinyl), poly(vinyl nitrile), poly(vinyl ester), polysulfonate, polysulfide, polysulfonamide, polyurea, or polyphosphazene. The thermoplastic polymer can include polyolefins, polycarbonates, polysulfones, polyetherimides, polyamides, polyesters (e.g., poly(ethylene terephthalate) or poly(butylene terephthalate)), polystyrene, polyethers (e.g., polyether ketone or polyether ether ketone), or polyacrylates (e.g., poly(methyl methacrylate)).

[0073] The thermoplastic polymer can include polyolefins. The polyolefins include at least one of homopolymers or copolymers. The polyolefins can have a general formula structure: CnH2n, where n can be from 2 to 20. The polyolefins can include at least one of the following: polyethylene, polypropylene, polyisobutylene, or polynorbornene. Examples of polyethylene include linear low density polyethylene (LLDPE), high density polyethylene (HDPE), and medium density polyethylene (MDPE). The polyolefins can include polyolefin copolymers, such as copolymers of ethylene with at least one of propylene, 1-butene, 1-octene, 1-decene, 4-methylpentene-1, 2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, 3-hexene, norbornene, or dienes (e.g., 1,4-hexadiene, monocyclic or polycyclic dienes). The polyolefin copolymers can include multiphase polyolefins, and the thermoplastic polymer can include polyethylene.

[0074] The thermoplastic composition can include additives. The additives can include at least one of the following: blowing agents, flame retardants, impact modifiers, flow modifiers, fillers (e.g., granular polytetrafluoroethylene (PTFE), glass, carbon, minerals, or metals), reinforcing agents (e.g., glass fibers), antioxidants, heat stabilizers, light stabilizers, ultraviolet (UV) light stabilizers, UV absorption additives, plasticizers, lubricants, release agents (such as mold release agents), antistatic agents, antifogging agents, antimicrobial agents, colorants (e.g., dyes or pigments), surface effect additives, radiation stabilizers, anti-dripping agents (e.g., PTFE encapsulated styrene-acrylonitrile copolymer (TSAN)), or combinations thereof. For example, a combination of a heat stabilizer, a mold release agent, and a UV light stabilizer can be used. Generally, the additives are used in amounts that are generally known to be effective.

[0075] The thermoplastic composition may include, for example, a blowing agent that foams at about 240 °C. The presence of the blowing agent can be used to absorb thermal energy to potentially prevent thermal runaway or prevent oxygen from contacting the surface of the polymer during combustion (expansion). The blowing agent may include a solid blowing agent, a liquid blowing agent, or a supercritical blowing agent. The blowing agent may be solid at room temperature and produce a gas (e.g., nitrogen, carbon dioxide, or ammonia) when heated to a temperature above its decomposition temperature, such as azodicarbonamide, metal salts of azodicarbonamide, 4,4'-oxybis(benzenesulfonylhydrazide), sodium bicarbonate, ammonium carbonate, etc. The blowing agent may include at least one of an inorganic reagent or an organic reagent. Examples of inorganic blowing agents include carbon dioxide, nitrogen, argon, water, air, nitrogen, ammonia, and inert gases such as helium and argon. Examples of organic reagents include aliphatic hydrocarbons having 1 to 9 carbon atoms, aliphatic alcohols having 1 to 3 carbon atoms, and fully and partially halogenated aliphatic hydrocarbons having 1 to 4 carbon atoms. Examples of aliphatic hydrocarbons include methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, etc. Examples of aliphatic alcohols include methanol, ethanol, n-propanol, and isopropanol. Examples of fully and partially halogenated aliphatic hydrocarbons include fluorocarbons, chlorocarbons, and chlorofluorocarbons. Examples of fluorocarbons include fluoromethane, perfluoromethane, fluoroethane, 1,1-difluoroethane, 1,1,1-trifluoroethane, 1,1,1,2-tetrafluoroethane, pentafluoroethane, difluoromethane, perfluoroethane, 2,2-difluoropropane, 1,1,1-trifluoropropane, perfluoropropane, dichloropropane, difluoropropane, perfluorobutane, perfluorocyclobutane, etc. Examples of partially halogenated chlorocarbons and chlorofluorocarbons include chloromethane, dichloromethane, chloroethane, 1,1,1-trichloroethane, 1,1-dichloro-1-fluoroethane, 1-chloro-1,1-difluoroethane, chlorodifluoromethane, 1,1-dichloro-2,2,2-trifluoroethane, 1-chloro-1,2,2,2-tetrafluoroethane, etc. Examples of perhalogenated chlorofluorocarbons include trichlorofluoromethane, dichlorodifluoromethane, trichlorotrifluoroethane, 1,1,1-trifluoroethane, pentafluoroethane, dichlorotetrafluoroethane, chloroperfluoropropane, and dichlorohexafluoropropane. Examples of other chemical reagents include azodicarbonamide, azobisisobutyronitrile, benzenesulfonylhydrazide, 4,4-oxyphenylsulfonyl semicarbazide, p-toluenesulfonyl semicarbazide, barium azodicarboxylate, N,N′-dimethyl-N,N′-dinitrosoterephthalamide, trihydrazinotriazine, etc.

[0076] The matrix material may include a flame retardant, such as, for example, a phosphate ester structure (e.g., resorcinol bis(diphenyl phosphate)), a sulfonated salt, a halogen, phosphorus, talc, silica, a hydrated oxide, a brominated polymer, a chlorinated polymer, a phosphorylated polymer, a nanoclay, an organoclay, a polyphosphonate / salt, a poly[phosphonate-co-carbonate], polytetrafluoroethylene, and a styrene-acrylonitrile copolymer, a polytetrafluoroethylene and a methyl methacrylate copolymer, a polysilixane copolymer, etc.

[0077] Examples of halogenated flame retardants include bisphenols, represented by the following: 2,2-bis-(3,5-dichlorophenyl)-propane; bis-(2-chlorophenyl)-methane; bis(2,6-dibromophenyl)-methane; 1,1-bis-(4-iodophenyl)-ethane; 1,2-bis-(2,6-dichlorophenyl)-ethane; 1,1-bis-(2-chloro-4-iodophenyl)ethane; 1,1-bis-(2-chloro-4-methylphenyl)-ethane; 1,1-bis-(3,5-dichlorophenyl)-ethane; 2,2-bis-(3-phenyl-4-bromophenyl)-ethane; 2,6-bis-(4,6-dichloronaphthyl)-propane; and 2,2-bis-(3,5-dichloro-4-hydroxyphenyl)-propane; 2,2 bis-(3-bromo-4-hydroxyphenyl)-propane. Other halogenated substances include 1,3-dichlorobenzene, 1,4-dibromobenzene, 1,3-dichloro-4-hydroxybenzene, and biphenyls such as 2,2'-dichlorobiphenyl, polybrominated 1,4-diphenoxybenzene, 2,4'-dibromobiphenyl and 2,4'-dichlorobiphenyl, and decabromodiphenylether, as well as oligomeric and polymeric halogenated aromatic compounds, such as copolycarbonates of bisphenol A and tetrabromobisphenol A with carbonate precursors such as phosgene. Metal synergists, such as antimony oxide, can also be used in combination with the flame retardant. When present, the halogen-containing flame retardant can be present in an amount of 1 to 25 parts by weight or 2 to 20 parts by weight based on 100 parts by weight of the total composition excluding any fillers.

[0078] Alternatively, the thermoplastic composition can be substantially free of chlorine and bromine. "Substantially free of chlorine and bromine" is defined as having a bromine or chlorine content of less than or equal to 100 parts per million (ppm), less than or equal to 75 ppm, or less than or equal to 50 ppm based on the total weight parts of the composition excluding any fillers.

[0079] The flame retardant may include a phosphorus-containing flame retardant. Flame retardant aromatic phosphates include triphenyl phosphate, tricresyl phosphate, isopropylated triphenyl phosphate, phenyl bis(dodecyl) phosphate, phenyl bis(neopentyl) phosphate, phenyl bis(3,5,5'-trimethylhexyl) phosphate, ethyl diphenyl phosphate, 2-ethylhexyl di(p-tolyl) phosphate, bis(2-ethylhexyl) p-tolyl phosphate, tricresyl phosphate, bis(2-ethylhexyl) phenyl phosphate, tri(nonylphenyl) phosphate, bis(dodecyl) p-tolyl phosphate, dibutylphenyl phosphate, 2-chloroethyl diphenyl phosphate, p-tolyl bis(2,5,5'-trimethylhexyl) phosphate, and 2-ethylhexyl diphenyl phosphate. Difunctional or polyfunctional aromatic phosphorus-containing compounds are also useful, such as resorcinol tetraphenyl diphosphate (RDP), bis(diphenyl) phosphate of hydroquinone and bis(diphenyl) phosphate of bisphenol A, and their oligomeric and polymeric counterparts. Flame retardant compounds containing phosphorus-nitrogen bonds include chlorophosphazene, phosphorus-containing ester amides, phosphoric acid amides, phosphonic acid amides, phosphinic acid amides and tris(aziridine)phosphine oxide. Aromatic phosphates can include difunctional or polyfunctional compounds or polymers. When used, phosphorus-containing flame retardants can be present in an amount of 0.1 to 30 parts by weight or 1 to 20 parts by weight based on 100 parts by weight of the total composition not including any filler.

[0080] Inorganic flame retardants include salts of C1-16 alkyl sulfonates, such as potassium perfluorobutanesulfonate (Rimar salt), potassium perfluorooctanesulfonate, tetraethylammonium perfluorohexanesulfonate, and potassium diphenylsulfonesulfonate; salts such as Na 2 CO 3 、K2CO 3 MgCO 3 、CaCO 3 and BaCO 3 , or fluoride anion complexes such as Li 3 AlF 6 、BaSiF 6 KBF 4 , K 3 AlF 6 , KAlF 4 , K 2 SiF 6 Or Na 3 AlF 6 When present, the inorganic flame retardant salt may be present in an amount of 0.01 to 10 parts by weight or 0.02 to 1 part by weight, based on 100 parts by weight of the total composition excluding any filler.

[0081] The thermoplastic composition can have a UL94 flame retardancy rating of V0 or better at a non-limiting thickness of 3.5 millimeters (mm), preferably 2 mm, or 1.5 mm, or 1 mm or less, as measured according to Underwriter’s Laboratory Bulletin 94 (UL94), titled “Tests for Flammability of Plastic Materials for Parts in Devices and Appliances” (ISBN 0-7629-0082-2), fifth edition, dated October 29, 1996 (incorporating revisions as of December 12, 2003 (including December 12)).

[0082] The matrix material may include one or more additives such as, for example, coupling agents that promote adhesion between the matrix material and the fibers of the unidirectional tape, antioxidants, heat stabilizers, flow modifiers, stabilizers, UV stabilizers, UV absorbers, impact modifiers, crosslinking agents, colorants, or combinations thereof. Non-limiting examples of coupling agents include POLYBOND 3150 maleic anhydride grafted polypropylene commercially available from DUPONT, FUSABOND P613 maleic anhydride grafted polypropylene commercially available from DUPONT, maleic anhydride ethylene, or combinations thereof. A non-limiting example of a flow modifier is CR20P peroxide masterbatch commercially available from POLYVEL INC. A non-limiting example of a heat stabilizer is IRGANOX B 225 commercially available from BASF. Non-limiting examples of UV stabilizers include hindered amine light stabilizers, hydroxydibenzophenone, hydroxyphenylbenzotriazole, cyanoacrylate, oxanilide, hydroxyphenyltriazine, and combinations thereof. Non-limiting examples of UV absorbers include 4-substituted-2-hydroxydibenzophenone and its derivatives, aryl salicylates, mono-esters of diphenols such as resorcinol monobenzoate, 2-(2-hydroxyphenyl)-benzotriazole and their derivatives, 2-(2-hydroxyphenyl)-1,3,5-triazine and their derivatives, or combinations thereof. Non-limiting examples of impact modifiers include elastomers / soft blocks dissolved in one or more matrix-forming monomers (e.g., bulk HIPS, bulk ABS, reactor-modified PP, LOMOD, LEXAN EXL, etc.), thermoplastic elastomers dispersed in the matrix material by compounding (e.g., diblock, triblock, and multiblock copolymers, (functionalized) olefin (co)polymers, etc.), predefined core-shell (substrate-graft) particles dispersed in the matrix material by compounding (e.g., MBS, ABS-HRG, AA, ASA-XTW, SWIM, etc.), or combinations thereof. Non-limiting examples of crosslinking agents include divinylbenzene, benzoyl peroxide, alkylene glycol di(meth)acrylate (e.g., glycol diacrylate, etc.), alkylene triol tri(meth)acrylate, polyester di(meth)acrylate, bisacrylamide, triallyl cyanurate, triallyl isocyanurate, (meth)allyl acrylate, diallyl maleate, diallyl fumarate, diallyl adipate, triallyl esters of citric acid, triallyl esters of phosphoric acid, or combinations thereof. In some unidirectional tapes, such additives may include pure polypropylene.

[0083] Returning to the above-mentioned drawing, the cover 102 of the battery pack for an electric vehicle may include a plastic sheet 104 that defines an edge perimeter sized to cover an opening of a battery cell support housing subassembly of the battery pack 102. The plastic sheet 104 includes a plurality of cover 102 fastening features adjacent to the edge perimeter, and the fastening features define a cover 102 fastening perimeter. The cover may include a reinforcement sheet 106 member coupled to and covering a portion of the plastic sheet 104, and the reinforcement sheet 106 member is configured to control or increase the burst pressure strain of the cover 102 relative to the separate plastic sheet 104. The reinforcement sheet 106 member may be configured to control or increase the burst pressure of the plastic sheet 104 to be higher than a specified burst pressure. The reinforcement sheet 106 member may have an insertion edge framed by the edge perimeter of the plastic sheet 104.

[0084] The reinforcement sheet 106 member may be thinner than a continuous fiber support insert member coupled to the battery pack to support the weight of the battery pack. The continuous fiber reinforced composite sheet member may be a first continuous fiber reinforced composite sheet member longitudinally spanning the plastic sheet 104. The cover may include a second continuous fiber reinforced composite sheet member that transversely spans the sheet and intersects the first composite member. The sheet members may be selected and placed on the cover 102 to alter the vibration characteristics of the cover 102 to a desired performance.

[0085] The cover 102 of the battery pack for an electric vehicle may include a plastic sheet 104 that defines an edge perimeter sized to cover an opening of a housing subassembly of the battery pack 102. The plastic sheet 104 includes a plurality of cover 102 fastening features adjacent to the edge perimeter, and the fastening features define a cover 102 fastening perimeter. The cover may include a continuous fiber reinforced composite sheet coupled to the plastic sheet 104. The housing subassembly may include at least one pair of load-bearing fastening features, where each member of the pair is disposed on opposite sides of the housing subassembly, and the pair of load-bearing fastening features is sized to withstand the weight of the battery pack when installed on the electric vehicle. The continuous fiber reinforced composite sheet may be disposed between the members of the pair of load-bearing fastening features.

[0086] The continuous fiber reinforced composite sheet may be coupled to the plastic sheet 104 and is substantially disposed within the cover 102 fastening perimeter, extending through the plastic sheet 104 along the width of the cover 102 fastening perimeter and being less than the distance between a first intersection of the width with the cover 102 fastening perimeter and a second intersection of the width with the cover 102 fastening perimeter.

[0087] The continuously fiber-reinforced composite thin plate can be coupled to the plastic thin plate 104 and define the periphery of the continuously fiber-reinforced composite thin plate. The continuously fiber-reinforced composite thin plate is substantially disposed within the edge periphery, surrounded by the plastic thin plate 104, and spaced apart from the edge periphery along most of the periphery of the continuously fiber-reinforced composite thin plate. The span of the continuously fiber-reinforced composite thin plate is less than the entire plastic thin plate 104.

[0088] The continuously fiber-reinforced composite thin plate can be coupled to the plastic thin plate 104, wherein the housing subassembly includes at least one pair of load-bearing fastening features, with each member of the pair disposed on opposite sides of the housing subassembly. The dimensions of the pair of load-bearing fastening features are configured to withstand the weight of the battery pack when installed in an electric vehicle. Wherein, the continuously fiber-reinforced composite thin plate can be disposed between the members of the pair of load-bearing fastening features.

[0089] The continuously fiber-reinforced composite thin plate member can be coupled to the plastic thin plate 104, cover a portion of the plastic thin plate 104, and have an insertion edge framed by the edge periphery of the plastic thin plate 104. The continuously fiber-reinforced composite thin plate member is configured to restrain the plastic thin plate 104 from anisotropically expanding as the internal volume of the battery pack increases under the pressure difference with the outside of the battery pack.

[0090] At least one continuously fiber-reinforced composite thin plate patch can be coupled to the plastic thin plate 104 and disposed within the fastening periphery of the cover 102. The at least one continuously fiber-reinforced composite thin plate patch can be one of a plurality of continuously fiber-reinforced composite thin plate patches.

[0091] The top cover 102 of the battery pack for an electric vehicle can include a plastic thin plate 104 that defines an edge periphery sized to cover the opening of the housing subassembly of the battery pack 102. The plastic thin plate 104 includes a plurality of cover 102 fastening features adjacent to the edge periphery, which define the cover 102 fastening periphery. The continuously fiber-reinforced composite thin plate member can be coupled to the plastic thin plate 104, and the continuously fiber-reinforced composite thin plate is configured to span the cover 102 fastening periphery to control or increase the burst pressure of the plastic thin plate 104 to be higher than the specified burst pressure.

[0092] A battery pack for an electric vehicle may include a top cover 102 subassembly and a bottom housing subassembly. The top cover 102 includes a plastic thin plate 104 that defines an edge perimeter sized to cover an opening of the housing subassembly of the battery pack. The plastic thin plate 104 includes a plurality of fastening features adjacent to the edge perimeter that define a fastening perimeter. A continuously fiber-reinforced composite thin plate member may be coupled to the plastic thin plate 104 and is configured to span the fastening perimeter to control or increase the burst pressure of the plastic thin plate 104 to be higher than a specified burst pressure. The bottom housing subassembly may define an internal volume subdivided by at least one reinforcing member spanning the width of the bottom housing. The bending stiffness of the top cover 102 subassembly may be less than the bending stiffness of the bottom housing subassembly.

[0093] The cover 102 of a battery pack for an electric vehicle may include a plastic thin plate 104 that defines an edge perimeter sized to cover an opening of the housing subassembly of the battery pack. The plastic thin plate 104 includes a plurality of fastening features adjacent to the edge perimeter that define a fastening perimeter. A continuously fiber-reinforced composite thin plate may be coupled to the plastic thin plate 104 and is substantially disposed within the fastening perimeter and extends through the plastic thin plate 104 along the width of the fastening perimeter, less than the distance between a first intersection of the width with the fastening perimeter and a second intersection of the width with the fastening perimeter.

[0094] A continuously fiber-reinforced composite thin plate member may be coupled to the plastic thin plate 104 and is sized to cover a continuously fiber-reinforced composite thin plate substantially disposed within the fastening perimeter and extends through the plastic thin plate 104 along the width of the fastening perimeter, less than the distance between a first intersection of the width with the fastening perimeter and a second intersection of the width with the fastening perimeter.

[0095] The cover 102 of a battery pack for an electric vehicle may include a plastic thin plate 104 that defines an edge perimeter sized to block an opening of the battery pack. The perimeter includes a plurality of fastening features adjacent to the edge of the perimeter that define a fastening perimeter. A continuously fiber-reinforced composite thin plate is coupled to the plastic thin plate 104 and the continuous fibers are substantially disposed within the fastening perimeter and extend through the plastic thin plate 104, less than the width of the fastening perimeter.

[0096] Embodiment

[0097] Some embodiments illustrate ribbing. The ribbing can be formed by co-injection molding, multi-shot molding, overmolding, or can be adhered to the components below them. The ribs can be spaced at intervals, such as evenly or unevenly spaced. In the following embodiments, a cover with dimensions of approximately 1800 mm in length, approximately 1473 mm in width, and approximately 45 mm in height is shown. The illustrated embodiments effectively replace a multi-material system with a single composite material hybrid system, saving up to 30% in weight compared to a metal system and reducing several assembly complexities.

[0098] Figure 3A Perspective view of the top of a battery cover without reinforcement. The drawing illustrates an all-plastic battery cover with integrated structural ribs. Figure 3B For Figure 3B Perspective view of the bottom of the cover. Figure 3A -B corresponds to Case 1. Case 1 depicts an all-plastic design without composite materials and has a thickness of 3.6 mm. Figure 8A Illustrates Figure 3A The deformation of the cover of -B at 38 kPa pressure. Figure 8B Illustrates the Figure 8A Cover at 50 kPa pressure. Figure 8C Illustrates Figure 8A The degradation of the stiffness of the cover of at 38 kPa pressure. Figure 8C.1 For Figure 8C The part marked Figure 8C.1 in Figure 8D Illustrates the Figure 8A Cover at 50 kPa pressure.

[0099] Figure 4A Perspective view of the top of a fully reinforced battery cover. Figure 4B For Figure 4B Perspective view of the bottom of the cover. The drawing illustrates a composite material hybrid battery cover with a continuous fiber laminate on the top. The plastic sheet 104 can include a pad formed of polypropylene. Figure 4A -B corresponds to Case 2. Case 2 depicts plastic with composite materials, fully covered, with a plastic thickness of 2.5 mm and a composite material thickness of 1.0 mm. Figure 9A Illustrates Figure 4A The deformation of the cover of -B at 38 kPa pressure. Figure 9B Illustrates the Figure 9A Cover at 50 kPa pressure. Figure 9C Illustrates Figure 9A The degradation of the stiffness of the cover of at 38 kPa pressure. Figure 9D Illustrates Figure 9A The degradation of the stiffness of the cover of at 50 kPa pressure. Figure 9D.1 ForFigure 9D The close-up of the part marked Figure 9D.1 in

[0100] Figure 5A is the perspective view of the top of the partially reinforced battery cover. Figure 5B is Figure 5B the perspective view of the bottom of the cover. This figure illustrates a composite hybrid battery cover with a continuous fiber laminate only in the local reinforcement area at the top. Figure 5A -B corresponds to Case 3. Case 3 depicts a plastic with a composite material, long and cross-shaped, having a plastic thickness of 3.5 mm and a composite material thickness of 1.0 mm. Figure 10A shows Figure 5A the deformation of the cover of -B under a pressure of 38 kPa. Figure 10B shows Figure 10A the cover of Figure 10C shows Figure 10A the degradation of the stiffness of the cover of Figure 10D shows Figure 10A the degradation of the stiffness of the cover of Figure 10D.1 is Figure 10D the close-up of the part marked Figure 10D.1 in

[0101] Figure 6A is the perspective view of the top of the partially reinforced battery cover. Figure 6B is Figure 6B the perspective view of the bottom of the cover. This figure illustrates a composite hybrid battery cover with a continuous fiber laminate only along the transverse axis at the top. Figure 6A -B corresponds to Case 4, depicting a plastic with a composite material, only cross-shaped, having a plastic thickness of 2.5 mm and a composite material thickness of 1.0 mm. Figure 11A shows Figure 6A the deformation of the cover of -B under a pressure of 38 kPa. Figure 11B shows Figure 11A the cover of Figure 11C shows Figure 11A the degradation of the stiffness of the cover of Figure 11D shows Figure 11A the degradation of the stiffness of the cover of Figure 11D.1 is Figure 11D the close-up of the part marked Figure 11D.1 in

[0102] Figure 7Perspective view of the bottom of a partially reinforced battery cover, showing ribs molded onto the reinforcement. This figure illustrates a composite hybrid battery cover with a continuous fiber laminate along the transverse axis on the bottom. Figure 7 Corresponds to Case 5. Case 5 depicts a plastic with a composite material, internally crossed, having a plastic thickness of 3.5 mm and a composite material thickness of 1.0 mm. Figure 12A Shows Figure 7 the deformation of the cover at 38 kPa pressure. Figure 12B Shows the Figure 12A cover at 50 kPa pressure. Figure 12C Shows Figure 12A the degradation of the stiffness of the cover at 38 kPa pressure. Figure 12C.1 Is Figure 12C a close-up of the part marked Figure 12C.1 in Figure 12D Shows Figure 12A the degradation of the stiffness of the cover at 50 kPa pressure. Figure 12D.1 Is Figure 12D a close-up of the part marked Figure 12D.1 in. Case 1 shows an undesired burst at certain selected pressures, while Cases 2 - 5 show a controlled burst at certain selected pressures.

[0103] As used herein, the term "vehicle" or "vehicular" or other similar terms generally includes motor vehicles such as passenger cars including sport utility vehicles (SUVs), buses, trucks, various commercial vehicles, vessels (including various boats and ships), aircraft, etc., and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., fuels derived from resources other than petroleum). As described herein, a hybrid vehicle is a vehicle having two or more power sources, such as a vehicle with gasoline power and electric power.

[0104] The term "coupled" is defined as being connected, although not necessarily directly and not necessarily mechanically; two items that are "coupled" may be integral to each other. Unless the present disclosure otherwise expressly requires, the terms "a" and "an" are defined as one or more. For example, unless the context clearly indicates otherwise, "an element" has the same meaning as "at least one element". The term "combination" includes blends, mixtures, alloys, reaction products, etc. Further, "at least one" means that the list includes each individual element, and combinations of two or more of the elements in the list, as well as combinations of at least one of the elements in the list with similar elements not mentioned. "Or" means "and / or". As used herein, the prefix "(one or more)" is intended to include both the singular and plural of the term it modifies, thereby including one or more of that term (e.g., (one or more) membranes includes one or more membranes).

Claims

1. A cover for a battery pack of an electric vehicle, comprising: a plastic sheet that defines an edge periphery sized to cover an opening of a housing sub - assembly of the battery pack, the plastic sheet being formed of a resin matrix filled with chopped glass fibers having a length of 10 mm or less, the plastic sheet including a plurality of cover fastening features proximate the edge periphery, the cover fastening features defining a cover fastening periphery; and a continuous fiber - reinforced composite sheet preform coupled to the plastic sheet, defining a boundary region of the plastic sheet around the continuous fiber - reinforced composite sheet preform such that the continuous fiber - reinforced composite sheet preform is spaced from the cover fastening periphery.

2. The cover according to claim 1, wherein the continuous fiber - reinforced composite sheet preform is a patch.

3. The cover according to any one of the preceding claims, wherein the span of the continuous fiber - reinforced composite sheet preform is less than the entire plastic sheet.

4. The cover according to any one of the preceding claims, wherein the plastic sheet is fused to the continuous fiber - reinforced composite sheet preform, and the cover further includes ribs fused to the continuous fiber - reinforced composite sheet preform.

5. The cover according to any one of the preceding claims, wherein the cover is a top cover for covering battery cells disposed in the housing sub - assembly, and the top cover has a bending stress lower than that of the housing sub - assembly.

6. The cover according to any one of the preceding claims, wherein the cover is an anisotropic expansion cover.

7. The cover according to any one of the preceding claims, wherein the continuous fiber - reinforced composite sheet preform is formed of unidirectional tapes that include continuous fibers disposed in a thermoplastic matrix.

8. The cover according to any one of the preceding claims, wherein the plurality of cover fastening features include metal eyelets overmolded by the plastic sheet.

9. The cover according to claim 8, wherein the plastic sheet is formed of polypropylene.

10. A cover for a battery pack of an electric vehicle, comprising: a plastic sheet that defines an edge periphery sized to cover an opening of a battery cell support housing sub - assembly of the battery pack, the plastic sheet being formed of a resin matrix filled with chopped glass fibers having a length of 10 mm or less, the plastic sheet including a plurality of cover fastening features proximate the edge periphery, the cover fastening features defining a cover fastening periphery; and a continuous fiber - reinforced composite sheet preform member coupled to the plastic sheet, covering a portion of the plastic sheet, the continuous fiber - reinforced composite sheet preform member configured to increase the burst pressure strain of the cover relative to the plastic sheet alone.

11. The cover according to claim 10, wherein the continuous fiber - reinforced composite sheet preform member is configured to increase the burst pressure of the plastic sheet to be higher than a specified burst pressure. ​ ​ 12. The cover according to any one of claims 10-11, wherein the continuous fiber-reinforced composite sheet preform member has an insertion edge framed by the peripheral edge of the plastic sheet.

13. The cover according to any one of claims 10-12, wherein the continuous fiber-reinforced composite sheet preform member is thinner than the continuous fiber support insertion member coupled to the battery pack to support the weight of the battery pack.

14. The cover according to any one of claims 10-13, wherein the continuous fiber-reinforced composite sheet preform member is a first continuous fiber-reinforced composite sheet preform member longitudinally spanning the plastic sheet.

15. The cover according to claim 14, comprising a second continuous fiber-reinforced composite sheet preform member transversely spanning the plastic sheet, which intersects the first composite member.

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