Structural energy storage integrated carbon fiber battery module as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of battery modules. The invention provides a structural energy storage integrated carbon fiber battery module as well as a preparation method and application thereof. The structural energy storage integrated carbon fiber battery module comprises a composite solid electrolyte matrix and a carbon fiber reinforcement, the composite solid electrolyte matrix comprises a sulfide solid electrolyte inner layer and an epoxy resin-based solid electrolyte outer layer, the inner layer and the outer layer are connected in an internal and external layering mode or a functional gradient mode, and the carbon fiber reinforcement penetrates through the inner layer and the outer layer. The battery module has the advantages that the structure and energy storage are integrated, the battery module has the bearing and energy storage functions, a traditional battery pack shell and a traditional support are not needed, and the number and the weight of components are greatly reduced; the solid electrolyte can reduce weight and improve efficiency, gives consideration to high energy density and excellent mechanical properties, improves safety and thermal stability, is high in whole vehicle integration degree, and improves safety and maintainability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery module, and particularly relates to a structural energy storage integrated carbon fiber battery module and a preparation method and application thereof. BACKGROUND

[0002] At present, new energy vehicles such as electric vehicles usually install battery packs as independent components on the vehicle body, and need additional support structures to fix and protect the batteries. This traditional design increases the vehicle mass and space occupation, limiting the endurance and efficiency. In order to reduce weight and improve space utilization, the concept of structural battery emerges as the times require: combining battery function with load-bearing structure, making the battery itself serve as a structural member, thereby realizing "no additional mass" energy storage, i.e. the so-called "massless battery" concept. Studies have shown that carbon fiber composite structural batteries can store certain electrical energy while providing high mechanical properties. For example, a carbon fiber laminated structural battery has been reported to have an energy density of about 33.4 Wh / kg, and a stiffness of about 38 GPa and a strength of about 234 MPa. Another study used carbon fiber as the negative electrode and coated lithium iron phosphate (LFP) coated carbon fiber as the positive electrode to prepare a full-carbon fiber-based structural battery, achieving an energy density of about 30 Wh / kg and more than 1000 cycles. These studies prove that structural batteries have great potential in weight reduction and integration, and their mechanical properties can reach a level close to that of aluminum alloy parts.

[0003] However, the existing structural battery technology still has many deficiencies: (1) Low energy density: the specific energy of about 30 Wh / kg is only about 20% of that of traditional lithium-ion batteries. The main reason is that the ionic conductivity of the composite material matrix used for bearing (such as epoxy resin-based solid electrolyte) is relatively low, limiting the electrochemical performance of the battery. Studies have shown that the ionic conductivity of epoxy resin-based polymer electrolytes at room temperature is usually only 10 -4 S / cm, even with the addition of plasticizers or fillers, it can only reach about 10 -3 S / cm. In contrast, inorganic solid-state electrolytes (especially sulfide-based) can reach 10 -2The existing structural battery has the following problems: (1) The mechanical properties of the existing structural battery are poor, and the ionic conductivity is less than 10-3 S / cm, but the mechanical properties are poor, the processing is difficult, and it is difficult to be directly used as a structural part. The existing structural battery mostly uses a single type of solid electrolyte (such as a pure polymer electrolyte), resulting in a trade-off between mechanical properties and electrical properties. (2) The structural integration degree is not high: some designs only embed battery cells in the structure, and the battery and the structure are still clearly distinguished, and the advantages of material integration are not fully utilized. (3) Manufacturing and integration are complex: integrating battery functions into the load-bearing structure requires solving problems such as material compatibility and process flow coordination, and there is currently a lack of mature multifunctional integrated manufacturing processes. (4) Safety and maintenance: once the structural battery is integrated into the vehicle body, the safety, sealing and module replacement and maintenance after a collision also face new challenges, such as how to conveniently repair or replace the failed battery cells while ensuring the structural integrity.

[0004] In summary, there is an urgent need for a battery module that can balance high ionic conductivity and high mechanical properties, and is more closely integrated with the vehicle body structure, thereby improving the endurance, safety and space utilization of new energy vehicles. SUMMARY

[0005] The purpose of the present application is to provide a structural energy storage integrated carbon fiber battery module and its preparation method and application to overcome the shortcomings of the prior art.

[0006] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0007] The present application provides a structural energy storage integrated carbon fiber battery module, which comprises a composite solid electrolyte matrix and a carbon fiber reinforcement.

[0008] The composite solid electrolyte matrix comprises a sulfide solid electrolyte inner layer and an epoxy resin-based solid electrolyte outer layer, and the inner layer and the outer layer are connected in an inner-outer layered manner or a functional gradient manner, and the carbon fiber reinforcement penetrates the inner layer and the outer layer.

[0009] As a preferred, the lithium ion conductivity of the sulfide solid electrolyte is ≥1×10 -3 S / cm.

[0010] As a preferred, the epoxy resin-based solid electrolyte comprises a thermosetting epoxy resin, a curing agent, a lithium salt and an ionic liquid; the mass of the lithium salt is 5-30% of the mass of the thermosetting epoxy resin, and the mass of the ionic liquid is 10-50% of the mass of the thermosetting epoxy resin.

[0011] As a preferred, the epoxy resin-based solid electrolyte further disperses an inorganic filler, the inorganic filler is alumina or ceramic nanoparticles, the ceramic nanoparticles comprise silicon dioxide, and the mass of the inorganic filler is 1-10% of the mass of the epoxy resin-based solid electrolyte.

[0012] As preferred, a functionally graded structure is formed between the sulfide solid electrolyte inner layer and the epoxy resin-based solid electrolyte outer layer, and the solid electrolyte composition is mainly sulfide and supplemented with epoxy resin near the inner layer, and is mainly epoxy resin and supplemented with sulfide near the outer layer, so that there is no obvious interface between the inner and outer layers, and smooth transition of ion conductivity and mechanical properties is realized.

[0013] As preferred, the battery module comprises a plurality of sub-module units combined into a whole through mechanical connection and electrical connection; each sub-module unit internally contains a plurality of solid-state battery cells connected in series and / or in parallel to form a sub-module battery pack; and the carbon fiber reinforcement is part of the electrode or the electrode current collector of the battery cell.

[0014] The application also provides a preparation method of the structural energy storage integrated carbon fiber battery module, comprising the following steps:

[0015] 1) mixing a positive active material, a conductive agent, and a sulfide solid electrolyte to form a positive electrode sheet, using a carbon fiber reinforcement as a negative electrode, and filling the sulfide solid electrolyte between the negative electrode and the positive electrode sheet after stacking to form a layered battery cell green body;

[0016] 2) impregnating the carbon fiber reinforcement in an epoxy resin-based solid electrolyte to obtain a prepreg, and laying the prepreg on the upper and lower sides of the layered battery cell green body to form a laminate;

[0017] 3) curing the laminate to obtain a cured carbon fiber battery module blank, and performing post-processing on the carbon fiber battery module blank to obtain a structural energy storage integrated carbon fiber battery module.

[0018] As preferred, the curing in step 3) is heating and pressurizing under vacuum or gradual cooling; the temperature of the heating under vacuum is 80-150 DEG C, the pressure of the pressurizing is 1-10 MPa, and the time of the heating and pressurizing under vacuum is 30-120 min; and the gradual cooling is cooling from 80-150 DEG C to room temperature.

[0019] The application also provides an application of the structural energy storage integrated carbon fiber battery module in a new energy vehicle, and the new energy vehicle comprises a vehicle body and a battery system, and the battery system comprises one or more structural energy storage integrated carbon fiber battery modules.

[0020] The beneficial effects of the application include the following points:

[0021] 1) structural and energy storage integration, weight reduction and efficiency improvement: the battery module itself has the functions of bearing and energy storage, and does not need a traditional battery pack shell and support, thereby greatly reducing the number and weight of components. Compared with the traditional design of separating the battery from the vehicle body, the weight of the whole vehicle can be reduced, and the energy utilization efficiency and the cruising range can be improved.

[0022] 2) High energy density with excellent mechanical properties: By introducing high- conductivity sulfide electrolyte inside, the electrochemical performance of the module is significantly better than that of the structural battery using only polymer electrolyte, which can output higher capacity and power per unit weight. The energy density of the module's integrated structure can reach 50-80 Wh / kg, which is higher than that of early commercial lithium iron phosphate battery packs, but its specific modulus and specific strength reach the level of high-performance composites (Young's modulus 30-60 GPa, tensile strength 300-600 MPa), which is enough to meet the requirements of vehicle body structure. This combination of performance far exceeds traditional battery pack shell materials, enabling vehicles to achieve "energy storage components as structural components".

[0023] 3) Solid-state electrolyte improves safety and thermal stability: The invention uses a full solid-state electrolyte system, avoiding the risk of leakage of flammable liquid electrolyte, improving the intrinsic safety of the battery. Sulfide and cured epoxy resin are not flammable, and the module has no risk of fire or explosion in abuse tests such as needle puncture and extrusion, and the possibility of thermal runaway is greatly reduced. In addition, the module remains stable within a wide temperature range of -20 to +80°C, and there is no problem of liquid electrolyte freezing at low temperature or boiling at high temperature, with excellent heat resistance and environmental adaptability. The Tg of the outer epoxy resin-based solid-state electrolyte is relatively high (80-90°C), ensuring that the module remains stable in structure and electrical performance under normal operating conditions (such as high-temperature exposure to 50-60°C inside the vehicle).

[0024] 4) Functionally graded design optimizes overall performance: The layered / gradient composite structure allows each component of the material to perform its function: the inner layer of high-conductivity electrolyte ensures fast ion transport and battery performance, and the outer layer of high-strength material provides the necessary stiffness and toughness support. The gradient transition reduces the mismatch problem caused by direct contact between different materials, such as the risk of interface peeling caused by thermal expansion and contraction differences, extending the cycle life. At the same time, carbon fibers run continuously through the inner and outer layers, providing strength while acting as a conductor, organically connecting the multiple layers of material. This multifunctional integrated design gives the module excellent overall performance, a breakthrough in traditional single-function material design.

[0025] 5) Manufacturing process integration and scale application: The manufacturing process of the invention combines composite material lamination molding with battery manufacturing, significantly reducing assembly steps. The hot press molding process simultaneously completes cell packaging and structure curing, with higher efficiency and better product consistency. The materials and processes used are compatible with existing composite materials and lithium battery industries (such as carbon fiber prepreg technology, solid-state battery sheet technology, etc.), facilitating large-scale production and application promotion. The module shape and size can be customized according to the vehicle body design and easily integrated into the vehicle body manufacturing process. For example, the module can be laid directly on the vehicle body floor assembly stage without the need for separate installation of heavy battery packs.

[0026] 6) High integration degree, improving safety and maintainability: When installed as part of the vehicle body, the module can become part of the vehicle frame, lowering the vehicle's center of gravity and optimizing space layout. The flat and wide shape of the module is conducive to heat management, with a large passive heat dissipation area. If necessary, cooling pipes can also be arranged inside the module to achieve efficient cooling. The carbon fiber-epoxy resin outer layer of the module itself is a good impact protection shell that absorbs energy and protects the internal battery from damage during side impact or bottom impact. At the same time, the module's frame and connectors are designed to be sealed, ensuring that the waterproof and dustproof level meets the vehicle's requirements (e.g. IP67 or higher), protecting the sensitive sulfide electrolyte inside from moisture corrosion. In terms of maintenance, the modular design makes battery replacement relatively simple: each module is connected through a standard interface, and when a fault occurs, the electrical connection can be disconnected and the local module can be removed and replaced without the need to disassemble the entire vehicle structure. In addition, through the built-in sensors and battery management system (BMS), the temperature, voltage strain, etc. of each unit can be monitored in real time, and when an anomaly is detected, an early warning is given in time to guide maintenance and ensure safety in use. DETAILED DESCRIPTION

[0027] The present application provides a structural energy storage integrated carbon fiber battery module, which comprises a composite solid electrolyte matrix and a carbon fiber reinforcement.

[0028] The composite solid electrolyte matrix comprises a sulfide solid electrolyte inner layer and an epoxy resin-based solid electrolyte outer layer, and the inner layer and the outer layer are connected in an inner-outer layered manner or a functional gradient manner, and the carbon fiber reinforcement penetrates the inner layer and the outer layer.

[0029] The layered structure refers to forming obvious partitions on the cross section of the composite material: the central part is the battery functional layer, and the two sides are the load-bearing structure layer, similar to a "sandwich" sandwich plate structure; the functional gradient structure gradually changes the composition ratio of the electrolyte matrix during the manufacturing process, for example, gradually reducing the content of sulfide electrolyte and increasing the content of epoxy resin-based material from the inside to the outside, so that the material performance gradually transitions from high ion conductivity to high mechanical strength, and the boundary between the two is blurred but the function is continuous. This gradient design can reduce stress concentration and ion transmission bottlenecks caused by interface discontinuity, significantly improving overall performance.

[0030] In the present application, the lithium ion conductivity of the sulfide solid electrolyte is preferably ≥1×10 -3 S / cm.

[0031] In the present application, the sulfide solid electrolyte preferably comprises a sodium chloride type sulfide electrolyte (Li6PS5Cl), a germanium-based sulfide electrolyte (Li(10)GeP2S(12)) or Li7P3S(11), and the room temperature ion conductivity of the sulfide solid electrolyte is 10 -3 ~ 10 -2 S / cm.

[0032] In the present application, the inner layer of sulfide solid electrolyte is the inner battery layer, and the outer layer of epoxy resin-based solid electrolyte is the outer structural layer. The inner battery layer provides the main ion conduction channel and electrochemical reaction environment, and the outer structural layer provides mechanical strength and environmental protection. The two kinds of matrix materials gradually transition at the interface to form a functional gradient structure, ensuring the balanced transition of ion conduction and mechanical strength, and avoiding interface stress concentration. The sulfide electrolyte is distributed in the form of powder or film between the positive and negative electrodes to form a continuous ion transport network. Since the mechanical strength of the sulfide electrolyte is usually low and it is easy to be brittle, the present application places it in the middle of the composite material by structural design, and it is constrained and supported by the peripheral reinforcing layer. At the same time, a certain proportion of elastic binder or filler (such as polymer or oxide nanoparticles) can be added to the sulfide electrolyte to improve its interface bonding and crack resistance in the composite structure.

[0033] In the present application, the epoxy resin-based solid electrolyte preferably comprises thermosetting epoxy resin, curing agent, lithium salt and ionic liquid. The mass of lithium salt is preferably 5-30% of the mass of thermosetting epoxy resin, further preferably 10-25%, and more preferably 15-20%. The mass of ionic liquid is preferably 10-50% of the mass of thermosetting epoxy resin, further preferably 15-45%, and more preferably 20-40%.

[0034] In the present application, the thermosetting epoxy resin is preferably glycidyl ether obtained by reacting bisphenol A, bisphenol F, bisphenol S, tetramethyl bisphenol A, diaryl bisphenol A, hydroquinone, o-dihydroxybenzene, m-dihydroxybenzene, cresol, tetraphenyl bisphenol A, triphenyl biphenyl, benzophenone, bis-m-dihydroxybenzene, bisphenol hexafluoroacetone, tetraphenyl bisphenol A, tetraphenyl bisphenol F, triphenyl phenol formaldehyde, bis-dimethylphenol, phenol novolac resin (phenol novolac), cresol novolac resin (cresol novolac), etc. polyphenol with epichlorohydrin, polyglycidyl ether obtained by reacting aliphatic polyol such as glycerol, neopentyl glycol, toluene, propylene glycol, hexanediol, polyether, polypropylene glycol with epichlorohydrin, glycidyl ether obtained by reacting inhibitor such as p-benzoic acid, β-benzoic acid ester with epichlorohydrin, polyglycidyl ester obtained from polymeric derivatives such as o-benzoic acid, methyl o-benzoic acid, m-benzoic acid, p-benzoic acid, tetrahydro-o-benzoic acid, bridging methylene tetrahydro-o-benzoic acid, bridging methylene hexahydro-o-benzoic acid, benzene meta-tricarboxylic acid, polymerization tower, glycidyl ester obtained from phenol, alkyl phenol, glycidyl ether obtained from phenol, glycidyl glycidyl ester obtained from phenol formic acid, glycidyl amine obtained from aniline, toluidine, triphenyl aniline, xylene diamine, diphenylcyclohexane, bisphenylcyclohexane, 4,4'-diphenylamine, 4,4'-diphenylamine synthesis, 4,4'-diphenyl ether, and known epoxy resins such as epoxidized polyolefins.

[0035] In the present application, the curing agent preferably comprises amine curing agent, acid anhydride curing agent, imidazole curing agent, phenolic compound;

[0036] The amine curing agent preferably comprises aliphatic amine, alicyclic amine, polyether amine, aromatic amine, polymeric amine, tertiary amine and its salt, modified amine; the aliphatic amine preferably includes ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), diethylamine (DEA), aminopropyl triethoxysilane (APTES); the alicyclic amine preferably includes isophorone diamine (IPDA), 1,3-cyclohexyl dimethylamine (1.3BAC), cyclohexylamine, methylcyclohexylamine (MCHA), dicyclohexylamine (DCH), 4,4'-diaminodicyclohexyl methane (PACM, HMDA); the aromatic amine preferably includes diaminodiphenyl methane (DDM), 4,4'-diaminostilbene, 4,4'-diaminodiphenyl sulfone (DDS), m-phenylenediamine (MPD), o-phenylenediamine (OPD), p-phenylenediamine (PPD); the polymeric amine preferably includes amine compound modified by any epoxy resin curing agent and epoxy compound polymerization, and the epoxy resin curing agent is present in excess in the reaction composition;

[0037] The tertiary amine and its salt preferably include triethylamine (TEA), trimethylamine (TMA), triethanolamine (TEOA), tetrabutylammonium chloride (TBAC), triethyl phenyl phosphonate.

[0038] In the present application, the acid anhydride curing agent preferably includes aliphatic acid anhydride, aromatic acid anhydride, alicyclic acid anhydride, special acid anhydride; the aliphatic acid anhydride is preferably an acid anhydride prepared from aliphatic diacid, including: succinic anhydride, glutaric anhydride, adipic anhydride, sebacic anhydride, dodecenyl succinic anhydride; the aromatic acid anhydride is preferably an acid anhydride prepared from aromatic diacid, including: phthalic anhydride, maleic anhydride, pyromellitic dianhydride, 3,3',4,4'-biphenyl dicarboxylic anhydride (BPDA), trimellitic anhydride (TMA), ketone tetracarboxylic dianhydride (BTDA); the alicyclic acid anhydride is preferably an acid anhydride prepared from alicyclic diacid, including: hexahydrophthalic anhydride (HHPA), methylhexahydrophthalic anhydride (MHHPA), tetrahydrophthalic anhydride (THPA), methyltetrahydrophthalic anhydride (MTHPA), dicyclopentadiene anhydride (DCPD), nadic anhydride, methyl nadic anhydride (MNA); the special acid anhydride is preferably a special modified acid anhydride curing agent, including: maleic anhydride, methyl-2-butene anhydride (MNA), maleic anhydride modifier, trifluoromaleic anhydride, hydrogenated anhydride (hydrogenated maleic anhydride, hydrogenated phthalic anhydride).

[0039] In the present application, the imidazole curing agent preferably includes monocyclic imidazole, imidazole derivative, bis-imidazole compound, imidazole salt, latent imidazole curing agent; the monocyclic imidazole is the most basic imidazole structure, and the monocyclic imidazole preferably includes imidazole, 1-methyl imidazole, 2-methyl imidazole, 4-methyl imidazole, 2-ethyl-4-methyl imidazole, 2-phenyl imidazole; the imidazole derivative is an imidazole ring with different substituents (such as alkyl, ester, amide, etc.) introduced, including long-chain alkyl imidazole, alkoxy imidazole, ester imidazole, amide imidazole, carboxyl imidazole; the bis-imidazole compound is connected by two imidazole rings through a covalent bond, including 4,4'-bisimidazolyl benzene (BIPB), 1,1'-bisimidazolyl ethane, 1,2-bisimidazolyl ethane, bisimidazolyl methane; the imidazole salt is a salt generated by imidazole and acid or other reactions, including imidazole tetrafluoroborate, imidazole phosphate, imidazole sulfate, imidazole p-toluene sulfonate; the latent imidazole curing agent refers to the imidazole modified by chemistry, which is stable and does not react at room temperature, but can be rapidly cured under heating conditions, including N-ethyl imidazole-2-carboxylate, N-phenyl imidazole derivative, capped imidazole compound; the phenolic compound preferably includes bisphenol A phenolic resin, phenol phenolic resin, naphthalene type phenolic resin, biphenyl phenol type phenolic resin, biphenyl phenol type naphthol resin, dicyclopentadiene phenol addition type resin, phenol aralkyl resin, naphthol aralkyl resin.

[0040] In the present application, the organic urea preferably includes one or a mixture of two of 3-phenyl-1,1-dimethyl urea, 1,3-diphenyl urea, 1,3-dimethyl urea, N-(3-chlorophenyl)-N',N'-dimethyl urea; common commercial organic urea accelerators, (1) Dyhard UR series (Evonik company): Dyhard UR 200 contains 1,3-dimethyl urea, used for low-temperature rapid curing; Dyhard UR 300 contains 3-phenyl-1,1-dimethyl urea, suitable for medium-temperature curing; Dyhard UR 500 contains 1,3-diphenyl urea, suitable for high-temperature curing, with higher heat resistance. (2) Curithane series (Huntsman company): Curithane 52 contains various phenyl and methyl substituted organic urea, widely used for medium-high temperature curing of epoxy resin; Curithane 75 is mainly aimed at rapid curing needs, suitable for electronic packaging materials. (3) Omicure series (CVC Thermoset Specialties company): Omicure U-24 contains phenyl urea accelerators, which can significantly reduce the curing temperature of dicyandiamide, suitable for low to medium temperature curing; Omicure U-410 contains 1,3-diphenyl urea, suitable for high-temperature curing, and improves heat resistance; Omicure U-52M contains various substituted urea, suitable for rapid curing applications.

[0041] In the present invention, the lithium salt is preferably lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) or lithium bis(fluorosulfonyl)imide (LiFSI), and the ionic liquid is a room temperature stable and non-flammable substance, preferably 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMI-TFSI) or PYR14-TFSI; the lithium salt and the ionic liquid give the resin cured product ionic conductivity.

[0042] The epoxy resin-based solid electrolyte serves as the outer structure and protective layer; the thermosetting epoxy resin is preferably bisphenol A epoxy resin DGEBA, bisphenol A epoxy resin E51 or polyethylene glycol diglycidyl ether epoxy resin PEGDGE; by controlling the content of lithium salt and ionic liquid, the ionic conductivity of the cured epoxy resin-based solid electrolyte can reach 10 at room temperature. -4 ~10 -3 S / cm, while maintaining good mechanical properties (such as a glass transition temperature Tg close to or exceeding 80°C). The outer composite material is impregnated with carbon fiber fabric and hot-pressed to form a strong shell that provides structural support, protection, and sealing functions.

[0043] In the present invention, an inorganic filler is preferably dispersed in the epoxy resin-based solid electrolyte. The inorganic filler is preferably aluminum oxide or ceramic nanoparticles, and the ceramic nanoparticles preferably contain silicon dioxide. The mass of the inorganic filler is preferably 1-10% of the mass of the epoxy resin-based solid electrolyte, more preferably 2-8%, and even more preferably 4-6%. The inorganic filler can improve mechanical strength and thermal stability.

[0044] In the present invention, the glass transition temperature of the epoxy resin-based solid electrolyte outer structure bearing layer is increased to ≥80° C., and the Young's modulus is increased by no less than 10%.

[0045] In the present invention, the fiber reinforcement is preferably high-strength carbon fiber fabric, more preferably T700-grade plain weave fabric; the positive electrode active material is preferably lithium iron phosphate (LFP) powder. T700 carbon fiber has an excellent strength-to-modulus ratio and good conductivity. LiTFSI has a wider electrochemical window and thermal stability than traditional LiPF6. EMI-TFSI ionic liquid is stable at room temperature and can increase the ion transference number of the polymer. The Li6PS5Cl sulfide electrolyte is easier to cold-press and has higher ionic conductivity than the oxide. The lithium iron phosphate (LFP) positive electrode is safe, stable, and has a long cycle life, making it very suitable for structural battery applications.

[0046] In the present application, the fiber reinforcement runs through the entire module and serves as the battery electrode current collector and even the electrode active material. On the one hand, the continuous carbon fiber fabric / prepreg in the outer structural layer serves as a skeleton reinforcement to improve the load-bearing capacity of the module; on the other hand, part of the carbon fiber electrode (such as pre-graphitized carbon fiber bundle) is inserted into the internal battery layer and directly serves as the negative electrode of the lithium ion battery (similar to the graphite negative electrode). The positive electrode adopts lithium energy storage material (such as lithium iron phosphate LFP or ternary positive electrode material) coated on a conductive substrate (such as lithium-plated carbon fiber fabric or aluminum foil), and is connected to the carbon fiber current collector through conductive connection. The conductivity of carbon fiber ensures the transmission of electrons within the composite structure, thereby eliminating the traditional copper / aluminum current collector and greatly reducing the weight.

[0047] In the present application, a functional gradient structure is preferably formed between the sulfide solid electrolyte inner layer and the epoxy resin-based solid electrolyte outer layer, and the solid electrolyte composition is mainly sulfide and supplemented with epoxy resin near the inner layer, and is mainly epoxy resin and supplemented with sulfide near the outer layer, so that there is no obvious interface between the inner and outer layers, and the smooth transition of ion conductivity and mechanical properties is realized.

[0048] In the present application, the battery module includes a plurality of sub-module units combined into a whole through mechanical connection and electrical connection; each sub-module unit internally contains a plurality of solid-state battery cells connected in series and parallel to form a sub-module battery pack; and the carbon fiber reinforcement is the electrode current collector or part of the electrode of the battery cell.

[0049] In the present application, the carbon fiber reinforcement serves as the negative electrode material, the positive electrode active material, the conductive agent, and the sulfide solid electrolyte are mixed to form a positive electrode sheet, and the negative electrode and the positive electrode sheet are stacked and filled with sulfide solid electrolyte in the middle, thereby forming the at least one solid-state battery cell.

[0050] In the present application, the edges of the sub-module units are provided with sealing frames and standard electrical connection ports to facilitate the connection, sealing and maintenance of the sub-module units and the vehicle electrical system. According to the required voltage capacity of the electric vehicle, a plurality of battery cells (monomers) can be integrated in a single structural module. These units can be combined in series and parallel, connected by internal wires or conductive fibers, thereby forming a battery module that meets the requirements of the whole vehicle. Each battery cell in the module is packaged by the above-mentioned carbon fiber reinforced solid electrolyte structure, realizing the integration from monomer to module. The external electrical interface (such as positive and negative terminals and signal interface) of the module is reserved to facilitate connection with the vehicle circuit and battery management system (BMS). Multiple modules can also be connected mechanically into larger structures, such as different partition modules of the vehicle body floor connected by flange bolts or adhesive connection, realizing structural continuity and electrical series connection.

[0051] The application also provides a preparation method of the structural energy storage integrated carbon fiber battery module, comprising the following steps:

[0052] 1) mixing a positive active material, a conductive agent and a sulfide solid electrolyte to form a positive electrode sheet, using a carbon fiber reinforcement as a negative electrode, filling the sulfide solid electrolyte between the negative electrode and the positive electrode sheet after stacking to form a layered battery cell green body;

[0053] 2) impregnating the carbon fiber reinforcement in an epoxy resin-based solid electrolyte to obtain a prepreg, laying the prepreg on the upper and lower sides of the layered battery cell green body to form a laminate;

[0054] 3) curing and forming the laminate under vacuum heating and pressurization to obtain a cured carbon fiber battery module blank; and performing post-processing on the carbon fiber battery module blank to obtain a structural energy storage integrated carbon fiber battery module.

[0055] In the application, step 2) preferably adds a sulfide-epoxy mixed layer or changes the proportion of the matrix material layer by layer between the layered battery cell green body and the prepreg layer to form a functional gradient transition structure; and the laminate is heated and pressurized under vacuum conditions to cure the epoxy resin matrix and bond the layers into one body.

[0056] In the application, the curing and forming in step 3) is preferably vacuum heating and pressurization or stepwise cooling; the temperature of the vacuum heating is preferably 80-150℃, further preferably 90-140℃, more preferably 100-130℃, the pressure of the pressurization is preferably 1-10MPa, further preferably 2-8MPa, more preferably 3-6MPa, and the time of the vacuum heating and pressurization is preferably 30-120min, further preferably 40-100min, more preferably 60-80min; the stepwise cooling is preferably cooling from 80-150℃ to room temperature, and the cooling rate of the cooling is preferably 3-8℃ / min, further preferably 5-6℃ / min.

[0057] In the application, the curing and forming can be resin transfer molding (RTM) process to inject the epoxy resin prepolymer and then heat and cure; and slow cooling after curing to reduce thermal stress, and tempering or post-curing treatment when necessary to improve the performance of the module.

[0058] In the application, the post-processing in step 3) is trimming the module blank, connecting electrode lead terminals, installing monitoring sensors and control circuits, and sealing and protecting the outer surface and edges of the module to obtain the structural energy storage integrated carbon fiber battery module.

[0059] The application also provides application of the structural energy storage integrated carbon fiber battery module in a new energy vehicle, and the new energy vehicle comprises a vehicle body and a battery system, and the battery system comprises one or more structural energy storage integrated carbon fiber battery modules.

[0060] In the application, the battery module is installed as a part of the vehicle body structure to provide power for the vehicle; the battery module is fixed to the corresponding position of the vehicle body frame through fasteners or adhesion, and is connected with the electrical system of the vehicle through an electrical connector; the vehicle further comprises a thermal management device and a battery management system, which cooperate with the battery module to maintain the working temperature and monitor the state of the battery module, so that the power battery and the vehicle body structure are highly integrated.

[0061] The structural energy storage integrated carbon fiber battery module has load bearing function and energy storage function; the solid electrolyte matrix is formed by compounding the inner layer of high ionic conductivity sulfide solid electrolyte and the outer layer of epoxy resin-based solid electrolyte, the inner layer solid electrolyte is used for ion conduction of the battery unit, the outer layer of epoxy resin-based solid electrolyte is impregnated into the carbon fiber reinforcement to form a structural load bearing layer, and the inner layer and the outer layer are connected in a layered or functional gradient manner to transition into an integrated body.

[0062] The technical solutions provided by the application will be described in detail below in combination with the embodiments, but they should not be understood as limiting the protection scope of the application.

[0063] In the embodiments, the mold is a flat pressing mold (also called "opposite flat mold") comprising two pieces of flat plates matched with each other, the mold body is made of 1Cr18Ni9Ti stainless steel, and is subjected to surface hard oxidation or chrome plating treatment to improve the wear resistance and anti-adhesion performance; a 25 μm thick polyimide (PI) isolation sheet is arranged between the upper and lower molds to facilitate demolding and avoid adhesion of sulfide powder; a 0.5 mm thick peripheral limiting frame is arranged on the outer periphery of the upper and lower molds to ensure the consistency of the molding thickness, and a 0.05 mm exhaust gap is reserved to remove residual air in the powder layer in the initial stage of pressing. The mold can be installed in a 3 MPa vacuum hot press or a normal temperature cold press for use.

[0064] The carbon fiber negative electrode can be pre-lithiated by a metal lithium lamination infiltration method, comprising the following steps: first, place the surface-activated carbon fiber fabric (300℃ rapid drying for 3min) in an inert atmosphere and laminate with a 20μm thick lithium foil, and cover the outside with a 5μm copper foil to prevent oxidation; then, heat press at a temperature of 200℃ under a vertical pressure of 0.6MPa for 10min, so that the molten lithium metal infiltrates into the surface layer of the fiber bundle 8μm under the combined action of fiber capillary effect and external pressure; after heat pressing, remove the residual surface free lithium by light rolling of the double rollers or soft rollers at 80℃; finally, apply a 10nm Li3PO4 passivation / interface stabilization coating to the pre-lithiated fiber by in-situ sol spraying, to inhibit the subsequent side reaction with the sulfide solid electrolyte and improve the interface stability. After the above treatment, the reversible lithium intercalation capacity of the carbon fiber negative electrode can reach 100mAh / g, the initial coulomb efficiency is >90%, and the original mechanical strength and conductive continuity of the fiber are maintained, which is suitable for continuous production of large-area rolls or plates;

[0065] The hot press is a flat plate type hot press with a vacuum cavity, and the nominal model is VHP-300 (heating platform 300mm×300mm, double-sided heating up to 200℃, maximum loading pressure 10MPa, and limit vacuum-0.095MPa);

[0066] The aluminum-plastic composite film is selected to have a typical three-layer structure (PET / Al / PP), and the total thickness is controlled to be 75μm; wherein the thickness of the aluminum foil core layer is 20μm, the outer layer PET is 25μm, and the inner layer heat-sealable PP is 30μm. This thickness can provide a water vapor transmission rate of <10 -3 cm 3 m -2 day -1 (40℃, 90%RH) and an oxygen transmission rate of <10 -4 cm 3 m -2 day -1 (1atm, 23℃) without significantly increasing the mass, which meets the long-term sealing and weather resistance requirements of structural batteries.

[0067] Preparation of carbon fiber sulfide-epoxy structural battery module in Example 1

[0068] High-strength carbon fiber fabric (plain weave fabric of T700 grade, fiber diameter 7μm, density 1.8g / cm 3) as the enhanced skeleton and electrode current collector. The epoxy resin-based electrolyte uses a mixed system of bisphenol A epoxy resin (E51) and curing agent (mass ratio of diethylene triamine curing agent to dicyandiamide curing agent is 3:6) at a mass ratio of 100:9, and incorporates 20% of the mass of the thermosetting epoxy resin LiTFSI lithium salt and 30% of the mass of the thermosetting epoxy resin EMI-TFSI ionic liquid. The sulfide solid-state electrolyte is Li6PS5Cl powder (particle size <20 μm), and the room temperature ionic conductivity is 3×10 -3 S / cm. The positive electrode active material uses lithium iron phosphate (LFP) powder (particle size 1 μm, specific capacity 160 mAh / g), and the positive electrode active material, conductive carbon black and sulfide electrolyte are mixed at a mass ratio of 50:5:45 to form a positive electrode composite film; the negative electrode is a carbon fiber fabric itself (pre-lithiated to embed part of the lithium ions).

[0069] The epoxy resin-based electrolyte mixture described above is fully stirred at room temperature to be uniform, and then is uniformly coated on the carbon fiber fabric using a doctor blade method to form a carbon fiber prepreg with a resin content of 35%. The temperature and time are controlled during the operation to prevent premature curing of the resin, the mixing and stirring temperature is 23°C, the time is 10 min, the vacuum degassing temperature is 25°C, the vacuum degree is -0.09 MPa, the time is 3 min; the temperature of the doctor blade impregnation is 24°C, the mixture is coated on the carbon fiber fabric, the single-side operation time is controlled within 5 min, the whole roll (or whole piece) is completed within 15 min, the surface drying is carried out at 40°C, the time is 2 min, the resin surface layer is slightly tackified but not gelled, the aluminum foil-nylon vacuum bag is sealed immediately after packaging, and then is transferred to -18°C for storage (warmed to 20°C for not less than 2 h before use) to seal the prepreg for standby.

[0070] The positive electrode composite film and the carbon fiber fabric negative electrode are cut into a size of 100 mm x 100 mm, a piece of uniformly spread Li6PS5Cl sulfide electrolyte powder layer (thickness 0.2 mm) is clamped between the two, and the two are placed in a mold and lightly pressed to form a sheet-shaped battery cell blank (the area of the cut positive electrode composite film and the negative electrode carbon fiber fabric is 100 mm x 100 mm; wherein the thickness of the LFP-sulfide positive electrode composite film is 0.10 mm, the thickness of the pre-lithiated carbon fiber fabric negative electrode after light pressing is 0.12 mm, and the thickness of the Li6PS5Cl electrolyte powder layer after spreading is 0.20 mm; after the above three layers are stacked, 0.3 MPa light pressure is applied for 30 s, the powder layer is initially densified and tightly adhered to the electrodes, and the total thickness after pressing is controlled to be 0.44 mm; considering that the subsequent laminated body (including the outer epoxy prepreg) will be further hot-pressed at 3 MPa for curing, the overall curing shrinkage is 8%, and the final thickness of the sheet-shaped battery cell blank is stably controlled at 0.40 mm, with a thickness tolerance of not more than ±0.02 mm, to ensure the geometric consistency and uniformity of the ion conduction path in the subsequent multi-layer stacking), which is equivalent to a solid-state battery core, wherein the carbon fiber fabric serves as the negative electrode current collector and negative electrode, the LFP composite film serves as the positive electrode, and the sulfide electrolyte powder fills the space between the two electrodes to form an electrolyte layer.

[0071] In the mold, the layers are laid in the following order: two layers of carbon fiber prepreg are placed at the bottom (as the bottom structural layer, the carbon fiber fabric layers are stacked at an angle of 0° / 90° staggered), the prepared battery cell blank is placed in the middle, and then two layers of carbon fiber prepreg are covered on top (as the top structural layer). In order to form a functional gradient, 10 wt% Li6PS5Cl powder is pre-mixed into one layer of prepreg near the battery core to achieve transition fusion with the middle Li6PS5Cl powder layer. After aligning the layers, seal them in a vacuum bag (vacuum degree -0.09 MPa, absolute pressure in the bag 11 kPa, maintain vacuum for not less than 10 min and conduct leakage detection, allowable pressure drop ≤0.005 MPa / 5 min, confirm no leakage before proceeding to subsequent hot-pressing and curing).

[0072] Place the mold in a hot press, heat to 120°C under a vacuum of -0.09 MPa, and apply a pressure of 3 MPa for 1 h, so that the epoxy resin-based electrolyte fully flows and penetrates and solidifies. During the curing process, the intermediate sulfide powder layer is consolidated into a dense layer under slight pressure, and a certain adhesion is achieved with the help of a small amount of epoxy resin infiltration. After curing is completed, cool to room temperature to obtain a solidified and shaped integrated battery module rough piece.

[0073] The edges of the module blank are trimmed, and the exposed electrode terminals are connected to nickel strips as positive and negative leads. The module peripheral edge is coated with a layer of silicone rubber to enhance the sealing and waterproof performance. Then a thin aluminum-plastic composite film is pasted on the surface of the module to further block the penetration of water and oxygen. Temperature sensors and voltage sensors are installed and led out to the module connector through pre-embedded wires. Finally, a flat-plate structure battery module with a size of 100mm x 100mm x 5mm is obtained.

[0074] Performance test of the flat-plate structure battery module of the present embodiment:

[0075] Electrochemical performance: constant current charge and discharge test of the battery module at room temperature, test equipment using 16-channel programmable battery test system CT-4008-5V10A-T (Neware, voltage accuracy ±0.02%, current accuracy ±0.05%); test channel is calibrated annually, meeting the IEC62660-1 accuracy requirements. Environmental conditions: test room temperature 25℃, relative humidity 40%; the module is placed in a thermostat for testing, the K-type thermocouple inside the box monitors the temperature in real time (error ±0.5℃). Wiring method: the positive and negative nickel strips of the module are connected to the test channel through a 4-wire (Kelvin) clamp, ensuring that the measurement resistance is ≤5mΩ; BMS is removed, and the prototype performance test is directly performed on the battery cell. Rated parameters: module nominal capacity 2.0Ah (calculated by 0.2C charge and discharge capacity), nominal voltage 3.20V (LFP / C system); therefore 1C = 2.0A, 2C = 4.0A.

[0076] Charging program (CC-CV): (1) constant current charging: 0.5C (1.0A) to voltage upper limit 3.60V; (2) constant voltage charging: maintain 3.60V until the current drops to 0.05C (0.10A) and stop; (3) stand for 10min, record open circuit voltage and surface temperature.

[0077] Discharge program (constant current): (1) 0.5C (1.0A) constant current discharge to voltage lower limit 2.00V; (2) stand for 10min, record the termination voltage and temperature rise; (3) the obtained discharge capacity is taken as the "cycle capacity".

[0078] Rate test: after completing 5 cycles of 0.5C, charge and discharge in turn according to 1C→2C→3C→0.5C for 3 cycles each; rate retention rate = different rate discharge capacity / 0.5C discharge capacity. In the patent, the 2C capacity retention rate is 90%, which is obtained from this.

[0079] Cycle life test: 1C charge / 1C discharge as one cycle, voltage window as above; total 100 cycles, record coulomb efficiency (η = Qdischarge / Qcharge) of each cycle; when η≥99% and capacity retention≥90%, it is considered qualified. During the test, insert 0.2C capacity recovery test every 20 cycles to facilitate tracking of attenuation.

[0080] AC-IR measurement: rest for 30 min after full charge; use built-in 1 kHz AC impedance module to measure AC internal resistance, take 5-point average; actually measured 5Ω±0.2Ω.

[0081] Data processing: specific capacity (Whkg -1 ) is calculated according to discharge energy / module weight (including outer film and sensor); if voltage exceeds or temperature >45℃, it is automatically stopped and recorded as an abnormality.

[0082] The above process parameters can ensure the repeatability and comparability of the test results, and are consistent with the "constant current and constant voltage charging and discharging" clause in GB / T31467.3-2015 "Power battery performance requirements and test methods".

[0083] The measured specific capacity is 62 Wh / kg (based on the total mass of the module), and the coulomb efficiency is maintained at more than 99% after the first 100 cycles. The module internal resistance (measured at 1 kHz AC impedance) is 5Ω, showing good ion conductivity, mainly due to the high ion conductivity of the internal sulfide layer. The module can still maintain stable output under rate charge and discharge, with a capacity retention rate of 90% at 2C rate, showing low polarization characteristics and excellent power characteristics.

[0084] Mechanical properties: the bending Young's modulus of the module is measured by three-point bending test to be 40GPa, the maximum bending stress reaches 320MPa, and the fracture toughness reaches 150kJ / m 2 . These values indicate that the module has reached the requirements of the automobile body structure in terms of carrying capacity. At the same time, tensile test is carried out, according to GB / T3354-2014 "Tensile properties test method for fiber reinforced plastic composites" (equivalent to ASTM D3039): sample type: long strip sample (250mm x 25mm) with parallel quadrilateral end and clamping pressure plate; loading rate: 2mm / min; environmental conditions: 23±2℃, 50±5%RH; take 5 parallel samples to measure the average interlaminar shear strength (converted from stress-strain curve fracture point)

[0085] ≥30MPa, without delamination or peeling of the cell-structure layer. The interlaminar shear strength of the module is more than 30MPa, showing good bonding of the delamination interface, without delamination of the cell layer and the structure layer.

[0086] Thermal stability and safety: the module was placed in an 80℃ environment for 100h, and there was no significant performance degradation and no structural changes; the module still worked normally after being placed at -20℃ for 24h, showing wide temperature adaptability. In the needle abuse test, a 5mm diameter steel needle was inserted through the center of the module, and there was no fire or explosion, only a small local temperature rise (<30℃) was monitored, which verified the safety and reliability of the all-solid-state electrolyte design. Impact test simulates vehicle collision: a 15kg weight was impacted on the module at a speed of 30km / h, and the module only showed slight deformation and surface cracks, the internal cell layer was intact, and there was no risk of leakage, proving that it has good impact resistance.

[0087] Example 1 shows that the structural battery module of the application can be successfully prepared and achieve the expected comprehensive performance, and on this basis, improvements and optimizations can be made for different application requirements.

[0088] Example 2: Optimization design of functionally graded solid-state electrolyte structure

[0089] The high-strength carbon fiber fabric, epoxy resin-based electrolyte, sulfide solid-state electrolyte, positive electrode composite film, and negative electrode of this example are the same as in Example 1, and the electrolyte distribution is designed to be gradient on the basis of Example 1. Specifically, from the center of the module to the outer layer, the content of the sulfide electrolyte is gradually reduced, and the proportion of the epoxy resin-based electrolyte is increased. In the central cell area, the content of the sulfide electrolyte Li6PS5Cl is 100% (pure sulfide layer thickness 0.2mm); the second layer outward is a mixed layer of sulfide electrolyte and epoxy resin-based electrolyte (mass ratio of sulfide electrolyte to epoxy resin-based electrolyte is 70:30, thickness of the second layer is 0.1mm); the third layer is an epoxy layer containing a small amount of sulfide filler (mass ratio of sulfide electrolyte to epoxy resin-based electrolyte is 20:80, thickness of the third layer is 0.1mm); the fourth layer outward is a pure epoxy-based electrolyte impregnated carbon fiber layer (thickness of several layers is 0.5mm).

[0090] During lamination, the above-mentioned mixed gradient layer is additionally laid, and one layer of 70% sulfide electrolyte + 30% epoxy resin-based paste mixture and another layer of 20% sulfide electrolyte + 80% epoxy resin-based electrolyte mixture are added on both sides of the cell, and then carbon fiber prepreg is stacked, and the hot pressing curing time is 1.5h to ensure complete curing of the thick section. Other process conditions are the same as in Example 1.

[0091] Compared with Example 1, the gradient design of this example significantly improves the interface bonding and overall performance. The bending strength of the module is increased to 350MPa, and the interlaminar shear strength is increased by 15%, which is due to the gradient transition reducing the stress concentration at the material interface, and the internal sulfide layer is not easy to become a weak surface under load.

[0092] The ion conductance performance of the module is also improved: after gradient design, the transition of the inner layer sulfide and the outer layer epoxy resin reduces the interface impedance, and the overall ion conductance of the module is measured to be increased by 25% (the AC impedance is reduced to 4Ω). The medium and high rate performance of the battery charge and discharge is obviously improved: the capacity retention rate is increased from 80% of example 1 to 85% at 5C rate, indicating that the ion transmission at the interface of the inner and outer electrolytes is smoother.

[0093] The cycle process of the thermal cycle test adopts a standard thermal cycle test sequence (which can refer to GB / T2423.22-2012 / IEC60068-2-14Nb or ASTMD7792), after 30 min of incubation at -20℃, the temperature is increased to 60℃ at a constant rate for 30 min, and then the temperature is decreased from 60℃ to -20℃ at a constant rate for 30 min, and the above is one cycle, one cycle is 2h, 50 cycles are completed, and a total of 100h; according to the requirement of IEC 60068-2-14, the environmental humidity is controlled at 20% RH to avoid frost; the monitoring items are open-circuit voltage and AC internal resistance measured every 10 cycles; after 50 cycles, 0.5C charge and discharge and three-point bending residual strength test are performed again to confirm that the electrical performance and mechanical performance attenuation is less than 5%.

[0094] Thermal cycle test After 50 times of repeated cycles between two temperatures, the module performance has no obvious attenuation, and there is no delamination or crack inside, which reflects the good thermal mechanical matching of the gradient structure. Due to the introduction of a certain proportion of epoxy resin in the gradient layer, the total energy density of the module slightly decreases (30Wh / kg, decreased by 6% compared with example 1), but higher mechanical reliability and power performance are obtained. The functionally graded structure can effectively improve the structure-electrochemical comprehensive performance of the module, so that the module of the application has more reliability and practical value in actual application.

[0095] Example 3

[0096] Change the sulfide electrolyte of example 1: replace Li6PS5Cl in example 1 with germanium-based sulfide electrolyte Li(10)GeP2S(12) (LGPS). LGPS powder has higher room temperature ion conductivity (up to 1×10 -2 S / cm). In terms of manufacturing process, in order to reduce the risk of decomposition of LGPS during high temperature curing, the hot pressing curing temperature is reduced to 100℃ and the time is extended to 2h. The ion conductive performance of the prepared module is further improved, and the room temperature AC impedance is only 3Ω, and it still remains >10 -3S / cm ionic conductivity. However, the mechanical properties decreased slightly (about 10% decrease in strength), which may be due to the slightly poor interface bonding caused by the harder LGPS particles. However, the overall performance still meets the requirements, proving that the material system of the present invention is compatible with different high ionic conductive sulfides.

[0097] Example 4

[0098] Changes to the reinforcing fibers and layup optimization of Example 1: The carbon fiber fabric is replaced with a high modulus carbon fiber unidirectional prepreg tape (M55J grade, elastic modulus 540GPa), which is laid along the main force direction to increase the stiffness of the structural parts. In terms of layup design, two layers of 0° unidirectional carbon fiber tapes are added to the upper and lower surfaces of the module, and the middle interlayer area is a fabric to balance the strength in all directions. Since high modulus fibers are relatively brittle and residual stress is easily generated during the curing and cooling process, a gradual cooling post-curing treatment is adopted (slowly cooling from 120°C to room temperature at a rate of 5°C / h). Tests show that the flexural modulus of the module of this embodiment is increased to 55GPa, which is very close to the stiffness of aluminum alloy or steel parts, but the impact toughness is reduced (by 20%). The module of this embodiment is suitable for use in areas with extremely high stiffness requirements and relatively mild impact loads.

[0099] Example 5

[0100] The rapid curing process of Example 1 was changed. In this embodiment, a thermoplastic-thermosetting dual-phase resin was used, whose gel time was only 15 minutes (at 150°C), and complete curing was completed within 30 minutes. The hot pressing process was adjusted to 150°C, a pressure of 5MPa, and a curing time of 30 minutes. Other conditions were the same as in Example 1. The results showed that the module of this embodiment can be cured and formed in a shorter time, and the performance is not significantly different from that of standard curing. The only difference is that the internal resistance of the module increases slightly (6Ω) because the rapid curing may cause the inner layer of sulfide powder to not have enough time to be fully dense. This can be improved by pre-pressing the sulfide layer before curing.

[0101] The process of the present invention can meet the needs of efficient industrial production. By selecting an appropriate resin system and equipment conditions, the molding cycle of a single module can be controlled to less than 1 hour, creating conditions for large-scale mass production. Examples 3 to 5 further demonstrate the diversity and adjustability of the materials and processes of the structural energy storage module of the present invention. In different application scenarios, the module performance can be optimized by changing the electrolyte material, fiber type, or adjusting the process.

[0102] Example 6 Vehicle cabin floor module prototype and integration test

[0103] This embodiment takes the cabin floor of a new energy vehicle as an example, and amplifies and integrates the module of the present invention into a prototype close to actual vehicle use to verify its performance under real working conditions.

[0104] Prototype module design: According to the chassis size of a SUV model, a floor type battery module with a size of 1200 mm x 1000 mm x 10 mm is designed, which is a flat plate that can cover most of the area of the driver's cabin floor. The module is composed of 4 sub-module units, each with a size of 600 mm x 500 mm, facilitating manufacturing and replacement. Each sub-module contains 20 solid-state battery cells (solid-state battery cells of Example 1), with a single cell (battery cell) capacity of 5 Ah. The 20 cells are connected in series to provide a total voltage of 72 V, and the 4 sub-modules are connected in parallel to form a module with a total voltage of 72 V and a capacity of 20 Ah (1.44 kWh of energy). The four sub-modules are connected into a whole through lap joint bolts and conductive connecting pieces, and are mechanically fixed to the four surrounding frame beams. The surface of the module is covered with a layer of anti-skid and wear-resistant coating material as the floor surface for passengers to step on.

[0105] Preparation and installation: Each sub-module is prepared by the method of Example 1, and then assembled into a whole floor module through mechanical and electrical connections. During installation, the module is placed in the chassis floor area, fixed by aligning the bolt holes, and connected to the main circuit by high-voltage wires. An additional layer of aluminum alloy protective plate (2 mm thick) is installed at the bottom of the module, mainly to resist the impact of flying stones and road debris, and also to act as a heat sink to help heat conduction. The module is connected to the vehicle cooling system: S-shaped spiral cooling pipes are attached to the bottom surface of the module, connected to the battery cooling circuit, and can be filled with cooling liquid to lower the module temperature when heat management is needed.

[0106] Vehicle power performance: The module is installed in a modified electric vehicle to replace the original battery, and the vehicle successfully starts and runs. The actual acceleration time from 0 to 50 km / h is 5.5 s, which is comparable to the original design; the vehicle reaches a maximum speed of 130 km / h, indicating that the module can provide stable power output. The vehicle's range has increased by 5%, partly due to the reduced weight (the original independent battery pack and floor weigh 80 kg, while the module assembly weighs 60 kg).

[0107] NVH (Noise, Vibration, and Harshness) and comfort: Since the module is a composite material structure with certain damping and vibration absorption performance, the vibration of the floor inside the vehicle is lower than that of traditional metal plates during actual road tests, and the comfort is improved. At the same time, the carbon fiber composite plate has good sound insulation performance, and the road noise is reduced. It can be seen that the module of the present application not only realizes energy storage, but also improves the NVH performance.

[0108] Thermal management effect: Under high load discharge (continuous discharge at 2C for 15 min), the module temperature uniformly rises to 45℃, and within 5 min after starting the cooling cycle, it drops below 30℃, indicating that the flat plate structure is beneficial to heat dissipation and the cooling measures are effective. Thermal imaging observation found that the module temperature distribution is uniform, with no hot spots, verifying the good thermal conductivity of the internal structure and the reasonable heat dissipation design.

[0109] Crash test: The vehicle body with the module of the present application installed was subjected to a simulated crash test according to the side pole crash test specification. The vehicle body structure was intact, no through crack occurred in the floor area where the module was located, only local delamination of carbon fiber occurred but still firmly bonded. After dissection of the module, no obvious damage was found in the internal battery cells, which could continue to work normally. This proves that the module has excellent structural load-bearing and energy-absorbing capacity, and can bear impact together with the vehicle body in vehicle crash, protecting the battery cells safe.

[0110] Maintenance convenience: In the test, one of the sub-modules was simulated to fail (the internal part of the cell connection was artificially disconnected), and the BMS successfully detected the failure and located the module. After the maintenance technician removed the seat and carpet, the failed sub-module was removed and replaced with a new spare part within 30 minutes, restoring the module function. This process shows the modular maintenance convenience of the module of the present application, which has a significant advantage over the traditional battery pack which needs to be disassembled for several hours.

[0111] The prototype test of Example 6 fully proves the feasibility and superiority of the module of the present application in vehicle application. The structural battery floor module takes into account the vehicle body structure function and battery function without affecting the performance of the vehicle, realizing true multi-functional integration.

[0112] Other application scenarios and additional function integration of Example 7

[0113] Application scenario A- roof structural battery: The module of the present application is applied to components such as roof or door of new energy vehicles to provide auxiliary power supply and improve component stiffness. The carbon fiber structural battery is used for the roof sunroof panel, which not only can be used as the bottom support structure of the solar panel, but also can store the energy obtained from solar energy for vehicle ventilation or lighting. Since the roof is relatively small in stress, the proportion of electric cells can be appropriately increased to improve the energy density. A 500mm x 500mm roof panel battery sample (6mm thick, containing 10 battery cells in series, 24V) was experimentally made, and its energy density reached 75Wh / kg, which can power the parking ventilation system for several hours. The stiffness of the roof panel sample is increased by 30% and the weight is reduced by 15% compared with the aluminum plate. This shows that the module of the present application also has application prospect on the secondary load-bearing components of the vehicle body, and the integrated energy utilization is more sufficient.

[0114] Application scenario B - chassis protection battery panel: the module of the present application is designed in the form of chassis protection panel, installed at the bottom of the vehicle, serving as both battery and chassis protection panel. The component is applied on off-road vehicles (with winch), providing additional power and protecting the chassis. For harsh environments, wear-resistant fillers (silicon carbide particles) are added to the outer epoxy matrix to improve stone impact resistance, and a layer of elastic polyurethane coating is applied to the surface to prevent water and mud. Tests show that the chassis battery panel remains sealed and functions normally after repeated sandstone impact, demonstrating good durability.

[0115] Functional expansion - sensing and intelligence: the module of the present application, due to the use of carbon fiber composite material, also facilitates the integration of optical fiber sensor or piezoelectric sensor network. In the carbon fiber layer of the module of embodiment 6, fiber Bragg grating (FBG) sensors are embedded for real-time monitoring of the strain and temperature distribution of the module. During vehicle driving and charging and discharging process, the FBG sensors accurately feedback the stress change and temperature rise of different areas of the module, providing valuable data for structural health monitoring (SHM) and battery thermal management. In the future, such sensing and module design can be combined to realize intelligent structural battery - both vehicle body and power supply, and self-monitoring and diagnosis, further improving the safety and reliability of the vehicle.

[0116] The structural energy storage integrated carbon fiber battery module provided by the present application can provide effective electrical energy storage for new energy vehicles without sacrificing structural performance, has high energy density, safety and durability, and can be widely applied to various components of the vehicle body to realize true multifunctional integrated design.

[0117] The battery module of the present application is prepared by combining the composite material forming process with the battery assembly process. For example: first, prepare the carbon fiber fabric layer of the pre-impregnated epoxy resin-based electrolyte and the battery functional layer sheet containing active materials and sulfide electrolyte; then, according to the designed layering sequence, lay the layers, alternately stack the carbon fiber fabric layer and the battery functional layer; then cure to cure the epoxy-based electrolyte to bond each layer and penetrate the sulfide layer, thereby obtaining an integrated composite battery panel. After curing, install the necessary busbars, terminals and BMS monitoring wiring harness, and perform edge sealing treatment (such as coating waterproof sealant or adding a frame shell) to prevent water and oxygen from entering the environment.

[0118] The battery module has the following advantages: ① high ion conductivity: by innovatively combining inorganic sulfide solid-state electrolyte and polymer-based solid-state electrolyte, the battery module as a whole has ion conduction performance close to that of traditional liquid lithium batteries, thereby reducing internal resistance and improving power and energy density; ② high mechanical property: by using carbon fiber reinforced composite material structure, strength and rigidity equivalent to those of conventional structural materials are achieved, thereby meeting the requirements of vehicle body load bearing and collision safety; ③ structure-energy storage integrated design: the functional layer of the battery cell and the load bearing structure layer are organically combined into a whole through layering or gradient manner, thereby avoiding the design of separating the traditional battery pack from the vehicle frame, improving system integration and reducing weight; ④ multi-functional safety integration: the module design takes into account the requirements of thermal management and collision protection, uses solid-state electrolyte to improve safety, and through optimized packaging, ensures waterproofness and dustproofness, and facilitates maintenance and replacement.

[0119] The above description is only preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A carbon fiber battery module with integrated structure and energy storage, characterized in that: The structural energy storage integrated carbon fiber battery module comprises a composite solid electrolyte matrix and a carbon fiber reinforcement; The composite solid electrolyte matrix comprises an inner layer of a sulfide solid electrolyte and an outer layer of an epoxy resin-based solid electrolyte. The inner layer and the outer layer are connected in an inner-outer layered manner or a functional gradient manner, and the carbon fiber reinforcement runs through the inner layer and the outer layer.

2. The structural energy storage integrated carbon fiber battery module according to claim 1, characterized in that: The lithium ion conductivity of sulfide solid electrolyte is ≥1×10 -3 S / cm.

3. The structural energy storage integrated carbon fiber battery module according to claim 1 or 2, characterized in that: The epoxy resin-based solid electrolyte comprises a thermosetting epoxy resin, a curing agent, a lithium salt and an ionic liquid; the mass of the lithium salt is 5 to 30% of the mass of the thermosetting epoxy resin, and the mass of the ionic liquid is 10 to 50% of the mass of the thermosetting epoxy resin.

4. The structural energy storage integrated carbon fiber battery module according to claim 3, characterized in that: Inorganic fillers are also dispersed in the epoxy resin-based solid electrolyte. The inorganic fillers are aluminum oxide or ceramic nanoparticles. The ceramic nanoparticles contain silicon dioxide. The mass of the inorganic fillers is 1-10% of the mass of the epoxy resin-based solid electrolyte.

5. The structural energy storage integrated carbon fiber battery module according to claim 4, characterized in that: A gradually transitioned functional gradient structure is formed between the inner layer of the sulfide solid electrolyte and the outer layer of the epoxy resin-based solid electrolyte. The solid electrolyte composition near the inner layer is mainly sulfide and supplemented by epoxy resin, while the solid electrolyte composition near the outer layer is mainly epoxy resin and supplemented by sulfide. As a result, there is no obvious interface between the inner and outer layers, achieving a smooth transition between ionic conductivity and mechanical properties.

6. The structural energy storage integrated carbon fiber battery module according to claim 4 or 5, characterized in that: The battery module includes multiple sub-module units, which are combined into a whole through mechanical and electrical connections; each sub-module unit contains several solid-state battery cells connected in series and parallel to form a sub-module battery pack; the carbon fiber reinforcement is the electrode collector or part of the electrode of the battery cell.

7. The method for preparing a carbon fiber battery module with integrated structure and energy storage according to any one of claims 1 to 6, characterized in that: The following steps are included: 1) The positive electrode active material, conductive agent and sulfide solid electrolyte are mixed to form a positive electrode sheet, the carbon fiber reinforcement is used as the negative electrode, the negative electrode and the positive electrode sheet are stacked, and the sulfide solid electrolyte is filled in the middle to form a layered battery unit green body; 2) Prepregs obtained by impregnating carbon fiber reinforcements with epoxy resin-based solid electrolytes are laid on the upper and lower sides of the layered battery unit green body to form a laminate; 3) The laminate is cured and formed to obtain a cured carbon fiber battery module blank; the carbon fiber battery module blank is post-processed to obtain a structural energy storage integrated carbon fiber battery module.

8. The preparation method according to claim 7, characterized in that Step 3) The curing molding is performed by heating and pressurizing under vacuum or gradually cooling; the heating temperature under vacuum is 80-150° C., the pressurizing pressure is 1-10 MPa, and the heating and pressurizing time under vacuum is 30-120 min; the gradual cooling is cooling from 80-150° C. to room temperature.

9. Application of the structural energy storage integrated carbon fiber battery module according to any one of claims 1 to 6 in new energy vehicles, characterized in that: The new energy vehicle comprises a vehicle body and a battery system, wherein the battery system comprises one or more structural energy storage integrated carbon fiber battery modules according to any one of claims 1 to 6.