A composite material battery casing and its manufacturing process

Abstract

This invention discloses a composite material battery casing and its manufacturing process, belonging to the field of battery casing technology. It includes a fiber-reinforced resin-based composite material forming the casing wall. The casing wall includes a load-bearing structural layer along its thickness direction and a thermal runaway self-evolution barrier layer located on the inner surface and integrally integrated with the load-bearing structural layer. By setting the load-bearing structural layer and the thermal runaway self-evolution barrier layer along the thickness direction of the casing wall, and by making the thermal runaway self-evolution barrier layer sequentially include a heat-absorbing buffer functional region, an expansion-to-carbon functional region, and a ceramicized barrier functional region, the casing wall forms a heat-absorbing buffer layer, a continuous carbonized heat insulation layer, and a dense ceramicized barrier layer according to temperature zones during thermal runaway, thereby reducing the external surface temperature rise and delaying the risk of casing burn-through.

Description

Technical Field

[0001] This invention relates to the field of battery casing technology, and more specifically, to a composite material battery casing and its manufacturing process. Background Technology

[0002] As power batteries develop towards higher energy density and higher integration, the requirements for battery system casings have gradually shifted from simple load-bearing and sealing to a comprehensive goal of simultaneously meeting lightweight structural support and safety protection under extreme operating conditions. Composite materials are used in battery casing structures due to their high specific strength, corrosion resistance, and high degree of molding freedom. However, under abnormal operating conditions such as thermal runaway, battery casings may experience transient releases of high-temperature gases and particles, pressure pulses within the cavity, and the diffusion of corrosive components and water vapor. These multi-physics coupled loads can easily lead to localized ablation of the casing wall, interface delamination, or sealing failure, further causing heat and flames to spread outwards. At the same time, there is often a coupling contradiction between the flame retardancy, heat insulation, and load-bearing performance of composite material casings. Simply relying on increasing the content of flame-retardant fillers can easily lead to a decrease in mechanical properties and an increase in process porosity. Simply using external heat insulation sheets or internal fire-resistant pads can increase assembly steps and failure interfaces, making it difficult to balance consistency and reliability under mass production conditions.

[0003] Existing technologies for battery casing safety protection often employ external fireproof and heat-insulating components, local thickening, or simple pressure relief holes. However, these methods are prone to two key shortcomings during thermal runaway. Firstly, the emission path of high-temperature gases lacks effective organization within the casing wall. Gas releases often randomly impact the casing structure, carrying corrosive components and moisture, causing secondary damage to the inner wall and surrounding connections, thus reducing subsequent barrier capabilities. Secondly, the functional layer design of composite material casing walls lacks a temperature-triggered sequential evolution mechanism. Common flame-retardant heat-insulating layers often fail to achieve a progressive protection process at different temperature zones, first absorbing heat for buffering, then forming a continuous carbonized heat-insulating layer, and finally forming a high-temperature ceramicized barrier layer. This leads to problems such as heat-insulating layer damage, increased risk of burn-through, or excessively rapid temperature rise on the outer surface during thermal runaway. Summary of the Invention

[0004] To address the problems mentioned in the background section, the present invention provides the following technical solution: A composite battery casing and its manufacturing process, comprising a fiber-reinforced resin-based composite material forming a casing wall, the casing wall having an inner surface facing the cell cavity and an outer surface opposite to the inner surface; The shell wall includes a load-bearing structural layer along the thickness direction and a thermal runaway self-evolution barrier layer located on the inner surface side and integrally combined with the load-bearing structural layer. The load-bearing structural layer is a continuous fiber reinforced resin matrix composite material layer, and the continuous fiber is at least one of carbon fiber, glass fiber, basalt fiber or aramid fiber. The volume fraction of the continuous fiber is 30% to 70%, and the resin matrix of the supporting structural layer is at least one of epoxy resin, bismaleimide resin or phenolic resin, and the glass transition temperature of the resin matrix is ​​not lower than 150°C. The thickness of the thermal runaway self-evolving barrier layer is 0.2 mm to 2.0 mm, and the thermal runaway self-evolving barrier layer includes a first functional area, a second functional area and a third functional area in sequence along the thickness direction from the side closer to the inner surface to the side closer to the outer surface; The first functional area includes at least one of phase change material microcapsules, metal hydroxide endothermic fillers, or carbonate endothermic fillers, and undergoes phase change endothermic or decomposition endothermic at a temperature of 120°C to 200°C. The second functional area includes an expanded carbonization system, which is composed of an acid source component, a carbon source component and a foaming source component, and forms a continuous carbonized heat insulation layer at a temperature of 220°C to 350°C. The third functional area includes ceramicized filler, which is at least one of silicate, borate, aluminosilicate or phosphate ceramicized filler, and forms a dense ceramicized barrier layer at a temperature not lower than 650°C. Furthermore, the shell wall also includes a flow guiding cavity network disposed between the supporting structure layer and the thermal runaway self-evolution barrier layer or disposed inside the supporting structure layer. The flow guiding cavity network extends along the thickness direction or in-plane direction of the shell wall and forms a connected gas discharge path. The inner wall of the flow guiding cavity network is provided with a capture liner, which includes a high-temperature resistant binder phase and an adsorption filler dispersed in the high-temperature resistant binder phase. The adsorption filler is at least one of metal oxide adsorption filler, molecular sieve adsorption filler or alkaline inorganic salt adsorption filler, so as to adsorb and capture acidic components and water vapor in the thermal runaway gas. The thickness of the capture liner is from 50 μm to 500 μm, and the mass fraction of the adsorbent filler in the capture liner is from 30% to 85%.

[0005] Furthermore, the flow guiding cavity network includes a buffer expansion section, a reversing flame extinguishing section, and a directional emission section connected in sequence; The equivalent volume of the buffer expansion section is greater than the equivalent volume of the deflection flame extinguishing section. The deflection flame extinguishing section includes at least two deflection channels and a porous flame arrestor disposed in the deflection channels. The porous flame arrestor is composed of an inorganic skeleton phase and a connecting hole structure. The pore size of the connecting hole structure is 0.2 mm to 2.0 mm. The inorganic skeleton phase includes at least one of the ceramicized fillers. The thickness of the capture liner at the folding flame extinguishing section is greater than the thickness of the capture liner at the buffer expansion section, and the capture liner at the folding flame extinguishing section further includes at least one of the ceramicized fillers; The shell wall also has a controllable fracture thin zone on the inner surface side near the flow channel network. The controllable fracture thin zone is made of locally thinned fiber-reinforced resin matrix composite material. The thickness of the controllable fracture thin zone is 0.15 mm to 0.80 mm, so that the gas in the thermal runaway state preferentially enters the deflection flame extinguishing section through the flow channel network and is discharged through the directional emission section.

[0006] Furthermore, it includes the following steps: A fiber preform is prepared and an inner surface region and an outer surface region facing the cell cavity are defined in the fiber preform. The inner surface region is used to form a thermal runaway self-evolving barrier layer, and the outer surface region is used to form a load-bearing structural layer. The fiber preform is arranged with sacrificial core materials and the sacrificial core materials are arranged to form a network of flow guiding cavities. The sacrificial core materials include a buffer expansion section core material, a reversing flame extinguishing section core material and a directional emission section core material that are connected in sequence. A trapping liner precursor is formed on the outer surface of the sacrificial core material. The trapping liner precursor includes a high-temperature resistant binder phase precursor and an adsorbent filler. Furthermore, ceramic filler is enriched on the outer surface of the corresponding folded-back flame-extinguishing section core material. A thermal runaway self-evolving barrier layer is formed by multi-stage infusion and curing into the inner surface side region. The multi-stage infusion is used to form a first functional region, a second functional region, and a third functional region in the inner surface side region. The multi-stage infusion includes sequentially infusing the first functional region formulation, the second functional region formulation, and the third functional region formulation. The first functional region formulation contains at least one of phase change material microcapsules, metal hydroxide endothermic fillers, or carbonate endothermic fillers. The second functional region formulation contains an expanded carbonization system composed of an acid source component, a carbon source component, and a foaming source component. The third functional region formulation contains at least one of ceramicized fillers. The infusion order and gelation time window of the first functional region formulation, the second functional region formulation, and the third functional region formulation are set to ensure that the first functional region, the second functional region, and the third functional region are sequentially layered along the thickness direction and maintain interface continuity. The supporting structural layer resin matrix is ​​injected into the outer surface side region and co-cured with the thermal runaway self-evolving barrier layer, so that the supporting structural layer and the thermal runaway self-evolving barrier layer are integrated and bonded together. After curing, the sacrificial core material is removed to form a flow channel network, and the capture liner precursor is cured and shaped to obtain a capture liner on the inner wall of the flow channel network.

[0007] Furthermore, the staged infusion includes curing the first functional area formulation to a pre-gel state before infusion and then infusion before infusion of the second functional area formulation, and curing the second functional area formulation to a pre-gel state before infusion before infusion of the third functional area formulation. The pre-gel state is the state in which the initial viscosity of the corresponding formulation increases to 2 to 8 times when infusion is completed and has not entered the curing exothermic peak. The initial viscosities of the first functional zone formulation, the second functional zone formulation, and the third functional zone formulation increase sequentially at 25°C, and are 200 mPa·s to 1500 mPa·s, 400 mPa·s to 2500 mPa·s, and 800 mPa·s to 5000 mPa·s, respectively. The gel times for the first functional area formulation, the second functional area formulation, and the third functional area formulation are 3 min to 15 min, 5 min to 25 min, and 8 min to 40 min, respectively. The infusion sequence, the pre-gel state, and the gelation time are coordinated to ensure that the first functional region, the second functional region, and the third functional region are sequentially layered along the thickness direction and maintain interface continuity, while restricting the reverse migration of the phase change material microcapsules, the metal hydroxide endothermic filler or the carbonate endothermic filler, the expanded carbonization system, and the ceramicized filler in the thickness direction.

[0008] Furthermore, when forming the capture liner precursor, the sacrificial core material is coated at least twice. The first coating is applied to the outer surface of the sacrificial core material to form a base coating layer, which is composed of a high-temperature resistant binder phase precursor and an adsorbent filler. The second coating is applied to the outer surface of the return flame extinguishing section core material to form a reinforcing coating layer, which is composed of a high-temperature resistant binder phase precursor, an adsorbent filler, and a ceramicized filler. After the second coating is completed, the capture liner precursor is pre-cured. The pre-curing process is to keep the temperature at 60°C to 120°C for 10 min to 90 min to make the capture liner precursor reach a surface dry state. The thickness of the substrate coating layer is 50 μm to 300 μm, the thickness of the reinforcing coating layer is 50 μm to 400 μm, and the ratio of the thickness of the reinforcing coating layer to the thickness of the substrate coating layer is 1.2 to 3.5; the mass fraction of the ceramicized filler in the reinforcing coating layer is 10% to 55%.

[0009] Furthermore, the step of removing the sacrificial core material to form the flow channel network includes: After the capture liner precursor reaches the surface dry state, the inlet and outlet ends of the sacrificial core material are connected to the guiding medium and a pressure difference is established. The pressure difference is 5 kPa to 30 kPa, so that the capture liner precursor adheres to the outer surface of the sacrificial core material. The sacrificial core material is removed by dissolution or melt removal. The dissolution method involves circulating and rinsing the material with water or a water-based solvent as the guiding medium at a temperature of 40°C to 90°C for 10 to 180 minutes. The melt removal method involves melting the sacrificial core material at a temperature of 70°C to 140°C and removing it with the guiding medium. After the sacrificial core material is removed, the capture liner precursor is subjected to a post-curing treatment, which is to maintain the temperature at 120°C to 180°C for 30 min to 180 min to obtain the capture liner and maintain the thickness stability of the base coating and the reinforcing coating.

[0010] Further, in the step of preparing the fiber preform, a thinning preformed region is formed at a predetermined position adjacent to the flow channel network and located on the inner surface side region. The thinning preformed region is obtained by setting the number of fiber lay-ups at the predetermined position to 0.3 to 0.8 times that of the non-thinning region or setting the fiber areal density at the predetermined position to 0.3 to 0.7 times that of the non-thinning region. Before injecting the load-bearing structural layer resin matrix into the outer surface side region, a peelable flow-limiting membrane is laid on the surface of the thinning preformed region. The peelable flow-limiting membrane is used to limit the excessive penetration of the load-bearing structural layer resin matrix into the thinning preformed region and control the resin enrichment in the thinning preformed region. After co-curing is completed and the peelable flow-limiting membrane is removed, a controllable cracking thin region is formed at the thinning preformed region. The thickness of the controllable cracking thin region is 0.15 mm to 0.80 mm, and the controllable cracking thin region is located on the inner surface side close to the flow channel network.

[0011] In summary, the present invention has the following beneficial effects: By setting a load-bearing structural layer and a thermal runaway self-evolving barrier layer in the thickness direction of the shell wall, and making the thermal runaway self-evolving barrier layer successively include a heat-absorbing buffer functional area, an expansion into carbon functional area, and a ceramic barrier functional area, the shell wall forms a heat-absorbing buffer layer, a continuous carbonized heat insulation layer, and a dense ceramic barrier layer according to the temperature zone during the thermal runaway process, thereby reducing the temperature rise of the outer surface and delaying the risk of shell burn-through.

[0012] By constructing a network of interconnected flow channels inside the shell wall and setting a capture liner on the inner wall of the flow channel network, and by setting a buffer expansion section, a reversal flame-extinguishing section and a directional emission section in the flow channel network, the thermal runaway gas can achieve pulsed slow release, flame extinguishing and energy reduction and directional emission inside the shell wall, and adsorb and capture acidic components and water vapor, thereby reducing secondary failures caused by random discharge impact and the diffusion of corrosive components.

[0013] By employing staged infusion and pre-gel window control, stable layering of the first, second, and third functional zones is achieved. Furthermore, by sacrificing core material forming and partitioned coating pre-curing, the thickness variation and adhesion stability of the capture liner are achieved. This ensures that the key structure maintains interface continuity, controlled filler migration, and reliable connectivity of the flow channel network under mass production conditions, thereby improving the overall consistency and reliability of the composite battery casing in terms of structural load-bearing and thermal runaway protection. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the integration of the shell wall thickness self-evolving barrier and the flow guiding cavity network of the present invention; Figure 2 This is a schematic diagram of the preparation process of the multi-stage injection layering and sacrificial core material forming of the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] The following is in conjunction with the appendix Figure 1-2 The present invention will be described in further detail below.

[0018] This invention provides a technical solution: a composite battery casing and its manufacturing process, comprising a fiber-reinforced resin-based composite material forming the casing wall, wherein the casing wall has an inner surface facing the cell cavity and an outer surface opposite to the inner surface; The housing wall has an inner surface facing the cell cavity and an outer surface opposite to the inner surface, characterized in that: The shell wall includes a load-bearing structural layer along the thickness direction and a thermal runaway self-evolution barrier layer located on the inner surface side and integrally combined with the load-bearing structural layer. The load-bearing structural layer is a continuous fiber reinforced resin matrix composite material layer, and the continuous fiber is at least one of carbon fiber, glass fiber, basalt fiber or aramid fiber. The volume fraction of the continuous fiber is 30% to 70%, and the resin matrix of the supporting structural layer is at least one of epoxy resin, bismaleimide resin or phenolic resin, and the glass transition temperature of the resin matrix is ​​not lower than 150°C. The thickness of the thermal runaway self-evolving barrier layer is 0.2 mm to 2.0 mm, and the thermal runaway self-evolving barrier layer includes a first functional area, a second functional area and a third functional area in sequence along the thickness direction from the side closer to the inner surface to the side closer to the outer surface; The first functional area includes at least one of phase change material microcapsules, metal hydroxide endothermic fillers, or carbonate endothermic fillers, and undergoes phase change endothermic or decomposition endothermic at a temperature of 120°C to 200°C. The second functional area includes an expanded carbonization system, which is composed of an acid source component, a carbon source component and a foaming source component, and forms a continuous carbonized heat insulation layer at a temperature of 220°C to 350°C. The third functional area includes ceramicized filler, which is at least one of silicate, borate, aluminosilicate or phosphate ceramicized filler, and forms a dense ceramicized barrier layer at a temperature not lower than 650°C. In this embodiment: The composite battery casing is formed by fiber-reinforced resin-based composite material to form the casing wall. The casing wall has an inner surface facing the cell cavity and an outer surface opposite to the inner surface. The casing wall is formed sequentially along the thickness direction by a load-bearing structure layer and a thermal runaway self-evolution barrier layer. The thermal runaway self-evolution barrier layer is located on the inner surface side and is integrated with the load-bearing structure layer. The thermal runaway self-evolution barrier layer is formed sequentially along the thickness direction from the side near the inner surface to the side near the outer surface by a first functional area, a second functional area and a third functional area.

[0019] In the preparation of the load-bearing structural layer, a blend of glass fiber and carbon fiber was selected as the continuous fiber. The areal density of the glass fiber was 600 g / m², and the areal density of the carbon fiber was 200 g / m². The fabric layup was a quasi-isotropic layup sequence alternating between 0° and 90°, with a total of 18 layers, so that the volume fraction of the continuous fiber was controlled at approximately 55%. The resin matrix was a bismaleimide resin system with a glass transition temperature of 190°C. A latent accelerator with a mass fraction of 0.8% was added to make the curing exothermic peak controllable. The target thickness of the load-bearing structural layer was 3.6 mm to 4.2 mm. After curing, the three-point flexural strength of the load-bearing structural layer at room temperature was not less than 620 MPa, and the flexural modulus was not less than 38 GPa.

[0020] In the preparation of the thermal runaway self-evolving barrier layer, the total thickness was set to 1.2 mm, with the thickness of the first functional area set to 0.35 mm, the thickness of the second functional area set to 0.45 mm, and the thickness of the third functional area set to 0.40 mm. Each functional area used the same type of high-temperature resistant resin to bind the continuous phase to ensure interfacial compatibility and integrated bonding. The high-temperature resistant resin binder was a modified phenolic resin, and the char residue after curing was not less than 55%. The sequential evolution of temperature zone triggering was achieved by controlling the filler system and filler mass fraction of each functional area.

[0021] The first functional zone employs an endothermic buffer system, which is composed of phase change material microcapsules and metal hydroxide endothermic fillers. The phase change temperature of the phase change material microcapsules is 152℃, the core material of the microcapsules is a paraffin-based phase change material, the microcapsule particle size D50 is 18μm, and the shell material of the microcapsules is melamine-formaldehyde resin treated with silane coupling. The metal hydroxide endothermic filler is aluminum hydroxide with a particle size D50 of 1.2μm. In the first functional zone, the mass fraction of phase change material microcapsules is 18%, the mass fraction of aluminum hydroxide is 32%, and the mass fraction of modified phenolic resin is 50%. During mixing in the first functional zone, the modified phenolic resin is preheated to 45℃, and aluminum hydroxide is added and dispersed for 20 minutes under stirring at 400 rpm. Then, the phase change material microcapsules are added at low shear at 200 rpm for 10 minutes. The initial viscosity of the resulting slurry is controlled at 900 mPa·s to 1300 mPa·s at 25℃ to avoid microcapsule breakage and ensure subsequent layering stability.

[0022] The second functional zone employs an expanded carbonization system, which consists of an acid source component, a carbon source component, and a foaming source component. The acid source component is ammonium polyphosphate with a degree of polymerization of 1000 to 1500. The carbon source component is pentaerythritol, and the foaming source component is melamine. In the second functional zone, the mass fraction of ammonium polyphosphate is 22%, the mass fraction of pentaerythritol is 10%, the mass fraction of melamine is 8%, and an expanded carbonization synergist with a mass fraction of 6% is added. The synergist is zinc borate. The mass fraction of modified phenolic resin in the second functional zone is 54%. During mixing in the second functional zone, ammonium polyphosphate and zinc borate are first dry-mixed evenly, then dispersed into the modified phenolic resin preheated to 50°C and stirred for 25 minutes. Subsequently, pentaerythritol and melamine are added and stirred for 10 minutes. The initial viscosity of the resulting slurry is controlled at 1200 mPa·s to 1900 mPa·s at 25°C to prevent significant sedimentation and stratification of the expanded carbonization system after stratification.

[0023] The third functional zone adopts a ceramicized filler system, which is composed of aluminosilicate ceramicized filler and borate flux filler. The aluminosilicate ceramicized filler is a compound powder of kaolin and mullite, with kaolin accounting for 18% by mass and mullite accounting for 22% by mass. The borate flux filler is borax, with a mass fraction of 6%. The modified phenolic resin in the third functional zone has a mass fraction of 54%. When mixing the third functional zone, kaolin and mullite are first dry-mixed and passed through a 200-mesh sieve. After adding the modified phenolic resin, the mixture is stirred at 600 rpm for 30 minutes. Then, borax is added and stirred for 10 minutes. The initial viscosity of the resulting slurry is controlled at 1800 mPa·s to 3200 mPa·s at 25°C to ensure that the third functional zone forms a dense section with enriched filler after stratification.

[0024] To ensure that the first, second, and third functional zones are sequentially layered along the thickness direction and maintain interface continuity, a three-layer layering and one-time co-curing process is performed on the inner surface of the preform of the load-bearing structural layer using the same mold. Specifically, the first functional zone slurry is first laid on the inner surface of the preform of the load-bearing structural layer and coated to a wet film thickness of 0.35 mm. Then, it is kept at 60°C for 12 minutes to allow the first functional zone to reach a pre-gel state. The pre-gel state is defined as a non-flowing surface that does not form continuous grooves when scraped with 0.5 N. Subsequently, the second functional zone slurry is laid on... The second functional area was pre-gelled by scraping a 0.45 mm wet film thickness and then kept at 60℃ for 15 min. The third functional area slurry was then spread and scraped to a 0.40 mm wet film thickness. Finally, the entire structure was co-cured. The curing curve was 90℃ for 40 min, then heated to 150℃ for 60 min, then heated to 200℃ for 90 min and cooled with the furnace. After curing, there was no visible delamination at the interface between the thermal runaway self-evolution barrier layer and the load-bearing structure layer. The width of the interface transition zone was 30 μm to 120 μm in cross-sectional microscopic observation.

[0025] To verify the sequential evolution effect of the thermal runaway self-evolving barrier layer in different temperature zones, the prepared shell wall was cut into 100mm x 100mm samples, with the inner surface facing the heat source, and a stepped heating experiment was conducted. The heating program was 120℃ for 10 min, 200℃ for 10 min, 350℃ for 10 min, and 650℃ for 10 min. In the 120℃ to 200℃ range, differential scanning calorimetry showed that the heat absorption per unit area of ​​the first functional zone was 65 kJ / m² to 110 kJ / m², and the temperature rise rate of the outer surface of the sample was more than 25% lower than that of the control sample without the first functional zone. At 220℃... At 350℃, the second functional zone forms a continuous carbonized heat insulation layer with an average thickness of 0.6mm to 1.4mm and a continuous coverage rate of no less than 90%. The highest temperature on the outer surface at 350℃ is more than 60℃ lower than that of the control sample without the second functional zone. At 650℃, the third functional zone is ceramized and forms a dense barrier layer with a continuous coverage rate of no less than 85%. The sample does not experience penetrating cracks under pressure of no less than 20N from a 1mm steel needle, and the outer surface of the sample shows a significant delayed temperature rise, with the outer surface temperature not exceeding 280℃ when held at 650℃ for 10 minutes.

[0026] In the above embodiments, the phase change material microcapsules and metal hydroxide endothermic fillers in the first functional region form an endothermic buffer in the range of 120°C to 200°C. The expanded carbonization system in the second functional region forms a continuous carbonized heat insulation layer in the range of 220°C to 350°C. The ceramicized fillers in the third functional region form a dense ceramicized barrier layer above 650°C. The sequential layering of the three components along the thickness direction and the pre-gelling layering process together ensure that the thermal runaway self-evolving barrier layer evolves sequentially according to the temperature zone during thermal runaway and maintains structural integrity. The load-bearing structural layer provides mechanical support and is integrated with the thermal runaway self-evolving barrier layer, thereby ensuring the synergy of the composite battery shell under normal temperature load and thermal runaway conditions.

[0027] Example 2 like Figure 1-2 As shown, the shell wall also includes a flow guiding cavity network disposed between the supporting structure layer and the thermal runaway self-evolution barrier layer or disposed inside the supporting structure layer. The flow guiding cavity network extends along the thickness direction or in-plane direction of the shell wall and forms a connected gas discharge path. The inner wall of the flow guiding cavity network is provided with a capture liner, which includes a high-temperature resistant binder phase and an adsorption filler dispersed in the high-temperature resistant binder phase. The adsorption filler is at least one of metal oxide adsorption filler, molecular sieve adsorption filler or alkaline inorganic salt adsorption filler, so as to adsorb and capture acidic components and water vapor in the thermal runaway gas. The thickness of the capture liner is 50 μm to 500 μm, and the mass fraction of the adsorbent filler in the capture liner is 30% to 85%. The flow channel network includes a buffer expansion section, a reversing flame extinguishing section, and a directional emission section connected in sequence; The equivalent volume of the buffer expansion section is greater than the equivalent volume of the deflection flame extinguishing section. The deflection flame extinguishing section includes at least two deflection channels and a porous flame arrestor disposed in the deflection channels. The porous flame arrestor is composed of an inorganic skeleton phase and a connecting hole structure. The pore size of the connecting hole structure is 0.2 mm to 2.0 mm. The inorganic skeleton phase includes at least one of the ceramicized fillers. The thickness of the capture liner at the folding flame extinguishing section is greater than the thickness of the capture liner at the buffer expansion section, and the capture liner at the folding flame extinguishing section further includes at least one of the ceramicized fillers; The shell wall also has a controllable fracture thin zone on the inner surface side near the flow channel network. The controllable fracture thin zone is made of locally thinned fiber-reinforced resin matrix composite material. The thickness of the controllable fracture thin zone is 0.15 mm to 0.80 mm, so that the gas in the thermal runaway state preferentially enters the deflection flame extinguishing section through the flow channel network and is discharged through the directional emission section.

[0028] In this embodiment: Besides the load-bearing structural layer and the thermal runaway self-evolution barrier layer, the composite battery casing also has a flow-guiding cavity network inside the casing wall. This network is located in the thickness section between the load-bearing structural layer and the thermal runaway self-evolution barrier layer and extends along the inward direction of the casing wall to form a connected gas discharge path. The flow-guiding cavity network sequentially connects to a buffer expansion section, a reversing flame-extinguishing section, and a directional discharge section. The buffer expansion section is configured as a partially expanded cavity to receive high-temperature gas pulses entering from the inner surface. The reversing flame-extinguishing section is configured as at least two stages of reversing flow channels to lengthen the flow path and reduce flame propagation. The directional discharge section is configured as a relatively stable discharge channel and connects to the discharge port on the outer side of the casing wall to achieve controlled discharge direction. In this embodiment, the equivalent volume of the buffer expansion section is 35 cm³. 3 Up to 90cm 3 The equivalent volume of the reversing flame-extinguishing section is 10 cm³. 3 Up to 30cm 3 The equivalent volume ratio between the two is controlled to be 1.8 to 5.5. The reversing flow channel of the reversing flame extinguishing section is two to four stages. The hydraulic diameter of a single reversing flow channel is 2.0 mm to 6.0 mm, and the reversing radius is 4.0 mm to 18.0 mm. The hydraulic diameter of the directional discharge section is 3.0 mm to 8.0 mm and the length is 40 mm to 220 mm.

[0029] A capture liner is provided on the inner wall of the flow guiding cavity network. The capture liner consists of a high-temperature resistant binder phase and an adsorption filler dispersed in the high-temperature resistant binder phase. The high-temperature resistant binder phase is selected from at least one of modified phenolic resin or modified siloxane resin to ensure adhesion strength under high-temperature scouring conditions. The adsorption filler is a composite system of metal oxide adsorption filler and molecular sieve adsorption filler. The metal oxide adsorption filler is a composite powder of MgO and Al2O3, and the molecular sieve adsorption filler is selected from at least one of 13X molecular sieve or ZSM-5 molecular sieve. The mass fraction of the adsorption filler in the capture liner is set to 50% to 80%, and the thickness of the capture liner is set to 80 μm to 420 μm. The thickness at the flaming reversal section is greater than that at the buffer expansion section. In this embodiment, the thickness of the capture liner at the buffer expansion section is set to 80μm to 180μm, and the thickness of the capture liner at the flaming reversal section is set to 220μm to 420μm, with a thickness ratio controlled to 1.5 to 4.5. Furthermore, the capture liner at the flaming reversal section is further supplemented with ceramicized filler to improve erosion and ablation resistance. The ceramicized filler is a composite system of aluminosilicate powder and phosphate powder. The mass fraction of the ceramicized filler in the capture liner at the flaming reversal section is set to 12% to 45%, so that the inner wall of the flaming reversal section forms a denser ceramicized skeleton under high temperature conditions and maintains the continuity of the liner.

[0030] A porous flame arrester is installed inside the reversing flow channel of the reversing flame extinguishing section. The porous flame arrester is composed of an inorganic framework phase and a connecting hole structure. The pore size of the connecting hole structure is 0.2 mm to 2.0 mm, and the D50 of the pore size distribution is controlled to be 0.6 mm to 1.2 mm. The inorganic framework phase includes at least one of the ceramic fillers and further includes SiO2 sol or phosphate binder to improve the room temperature molding strength. In this embodiment, the porous flame arrester adopts a strip or honeycomb structure and is embedded in the straight section of the reversing flow channel and near the reversing point. The volume fraction of the porous flame arrester accounts for 15% to 55% of the effective cross section of the reversing flow channel, so that the gas is diverted and heat exchanged when passing through the porous flame arrester and the flame front propagation is weakened. The porous flame arrester and the capture liner on the inner wall of the reversing flame extinguishing section form a cooperative interface. The capture liner preferentially adsorbs acidic components and water vapor and reduces the scouring of the porous flame arrester by carried particles. The ceramic filler further improves the structural integrity of the porous flame arrester at high temperature.

[0031] To ensure that gas preferentially enters the flow channel network and is guided along a predetermined path during thermal runaway, a controllable fracture thin region is provided on the inner surface of the shell wall near the flow channel network. This controllable fracture thin region is located at the inlet of the buffer expansion section and is connected to it. The controllable fracture thin region is composed of locally thinned fiber-reinforced resin-based composite material with a thickness of 0.15 mm to 0.80 mm. In this embodiment, the thickness is set to 0.30 mm to 0.55 mm, and the number of continuous fiber layups is controlled to be reduced to 0.4 to 0.7 times that of adjacent non-thinned areas. This allows the controllable fracture thin region to preferentially fracture locally, forming an air inlet when the temperature and cavity pressure increase. The effective opening area of ​​the air inlet is 0.5 cm². 2 Up to 4.0cm 2 Within the range of adaptive growth, after the air inlet is opened, the high-temperature gas first enters the buffer expansion section to complete the pulse slow release, and then enters the reversal flame extinguishing section. After passing through the porous flame arrestor to extinguish the flame and reduce energy, it fully contacts the capture liner, and then enters the directional emission section to achieve controlled emission direction.

[0032] To verify the synergistic effect of the capture liner and the reversible flame extinguishing section, a shell wall sample containing a network of guide cavities was placed in a sealed test chamber, and simulated exhaust gas was applied to the inner surface. The simulated exhaust gas contained 10% to 25% water vapor by volume and 0.05% to 0.30% acidic components by volume. The gas temperature was set to 260°C to 420°C, and pressure pulses of 15 kPa to 35 kPa were superimposed. The acidic component concentration downstream of the reversible flame extinguishing section and the temperature rise curve on the outer surface were recorded. In this embodiment, the peak concentration of acidic components downstream of the reversible flame extinguishing section was reduced by more than 60% compared to the inlet side. The adsorption capacity per unit area of ​​the capture liner on the inner wall of the reversible flame extinguishing section is 0.8 mg / cm² to 2.6 mg / cm², and no through-peeling occurs after 20 consecutive impacts. The porous flame arrester maintains structural integrity after continuous impacts, and the interconnected hole structure does not show obvious collapse. The flame propagation length at the outlet of the directional emission section is reduced by more than 40% compared to the comparison sample with only a straight-through discharge channel and no reversible flame extinguishing section or porous flame arrester. The maximum temperature rise on the outer surface is reduced by more than 30°C compared to the comparison sample with a thickened capture liner without a reversible flame extinguishing section, and the temperature rise curve is flatter.

[0033] Example 3 like Figure 1-2 As shown, it includes the following steps: A fiber preform is prepared and an inner surface region and an outer surface region facing the cell cavity are defined in the fiber preform. The inner surface region is used to form a thermal runaway self-evolving barrier layer, and the outer surface region is used to form a load-bearing structural layer. The fiber preform is arranged with sacrificial core materials and the sacrificial core materials are arranged to form a network of flow guiding cavities. The sacrificial core materials include a buffer expansion section core material, a reversing flame extinguishing section core material and a directional emission section core material that are connected in sequence. A trapping liner precursor is formed on the outer surface of the sacrificial core material. The trapping liner precursor includes a high-temperature resistant binder phase precursor and an adsorbent filler. Furthermore, ceramic filler is enriched on the outer surface of the corresponding folded-back flame-extinguishing section core material. A thermal runaway self-evolving barrier layer is formed by multi-stage infusion and curing into the inner surface side region. The multi-stage infusion is used to form a first functional region, a second functional region, and a third functional region in the inner surface side region. The multi-stage infusion includes sequentially infusing the first functional region formulation, the second functional region formulation, and the third functional region formulation. The first functional region formulation contains at least one of phase change material microcapsules, metal hydroxide endothermic fillers, or carbonate endothermic fillers. The second functional region formulation contains an expanded carbonization system composed of an acid source component, a carbon source component, and a foaming source component. The third functional region formulation contains at least one of ceramicized fillers. The infusion order and gelation time window of the first functional region formulation, the second functional region formulation, and the third functional region formulation are set to ensure that the first functional region, the second functional region, and the third functional region are sequentially layered along the thickness direction and maintain interface continuity. The supporting structural layer resin matrix is ​​injected into the outer surface side region and co-cured with the thermal runaway self-evolving barrier layer, so that the supporting structural layer and the thermal runaway self-evolving barrier layer are integrated and bonded together. After curing, the sacrificial core material is removed to form a flow channel network, and the capture liner precursor is cured and shaped to obtain a capture liner on the inner wall of the flow channel network. In this embodiment, a composite battery shell is prepared by in-mold partitioning and sacrificial core material forming. First, a fiber preform is prepared according to the thickness direction structural requirements of the shell wall. The fiber preform is formed by continuous fiber fabric layup, and the continuous fiber is selected from at least one of glass fiber or carbon fiber. During the layup process, partitioning and limiting boundaries are set in the mold for the inner surface side region and the outer surface side region. The inner surface side region serves as the layering region of the thermal runaway self-evolution barrier layer, and the outer surface side region serves as the impregnation and curing region of the load-bearing structural layer. After the outer surface side region is laid up, the fiber preform is vacuum dried at a temperature of 60°C to 90°C for a time of 30 min to 180 min to reduce the moisture content of the preform and stabilize the subsequent resin impregnation interface.

[0034] Subsequently, sacrificial core materials are arranged in the fiber preform to form a structurally interconnected network of flow channels. The sacrificial core material is selected from at least one of water-soluble polymer core materials or low-melting-point wax-based core materials. The sacrificial core material is molded in the mold in a continuous, interconnected structure to form a buffer expansion section core material, a reversing flame-extinguishing section core material, and a directional emission section core material—three interconnected segments in a single integral part. The equivalent volume of the buffer expansion section core material is set to 35 cm³. 3 Up to 90cm 3 The equivalent volume of the cavity of the flame-extinguishing section core material is set to 10cm³. 3 Up to 30cm 3 The hydraulic diameter of the core material in the directional discharge section is set to 3.0 mm to 8.0 mm; a gap is maintained between the sacrificial core material and the fiber preform through a limiting block, and the gap thickness is set to 0.5 mm to 4.0 mm as the target wall thickness dimension of the flow guide cavity network.

[0035] After the sacrificial core material is arranged, a capture liner precursor is formed on the outer surface of the sacrificial core material. The capture liner precursor consists of a high-temperature resistant binder phase precursor and an adsorption filler. The high-temperature resistant binder phase precursor is selected from at least one of modified phenolic resin precursor or modified siloxane resin precursor, and the adsorption filler is selected from at least one of metal oxide adsorption filler and molecular sieve adsorption filler. The mass fraction of the adsorption filler is set to 50% to 80%. The capture liner precursor is applied to the outer surface of the sacrificial core material by dip coating or spray coating and the thickness is controlled so that the coating thickness in the corresponding area of ​​the buffer expansion section is 80 μm to 180 μm. m, so that the coating thickness of the corresponding area of ​​the backflow flame extinguishing section is 220μm to 420μm; further add ceramic filler to the capture liner precursor in the corresponding area of ​​the core material of the backflow flame extinguishing section. The ceramic filler is selected from at least one of silicate, borate, aluminosilicate or phosphate filler, and the mass fraction of the ceramic filler is set to 12% to 45%; after the coating is completed, the capture liner precursor is pre-cured at a temperature of 60℃ to 120℃ for a time of 10min to 90min, so that the capture liner precursor reaches the surface dry state and maintains the adhesion stability in the subsequent pouring process.

[0036] A thermal runaway self-evolving barrier layer is formed by staged infusion and curing in the inner surface side region. The inner surface side region is sequentially formed into a first functional zone, a second functional zone, and a third functional zone along the thickness direction. The staged infusion sequentially uses the formulations for the first, second, and third functional zones. The formulation for the first functional zone contains at least one of phase change material microcapsules and metal hydroxide endothermic fillers, or at least one of phase change material microcapsules and carbonate endothermic fillers. The initial viscosity of the formulation for the first functional zone is controlled to be between 200 mPa·s and 1500 mPa·s at 25°C. The formulation for the second functional zone contains an expanded carbonization system, which consists of an acid source component, a carbon source component, and a foaming source component. The initial viscosity of the formulation for the second functional zone is controlled to be between 400 mPa·s and 2500 mPa·s at 25°C. The formulation for the third functional zone contains at least one of ceramicized fillers. The initial viscosity of the third functional zone formulation was controlled at 800 mPa·s to 5000 mPa·s at 25°C. The pouring sequence and gel time window were set according to the layer stability as follows: the first functional zone formulation was poured first and kept in the pre-gel state before the second functional zone formulation was poured, and then the third functional zone formulation was poured and the whole system was cured. The pre-gel state was defined by the viscosity ratio method as the system viscosity after the corresponding formulation was poured reaching 2 to 8 times the initial viscosity and not entering the curing exothermic peak. The gel time of the first functional zone formulation was set to 3 min to 15 min, the gel time of the second functional zone formulation was set to 5 min to 25 min, and the gel time of the third functional zone formulation was set to 8 min to 40 min. The process rhythm of the multi-stage pouring was coordinated with the pre-gel state to maintain the first, second and third functional zones in layers along the thickness direction and maintain the interface continuity.

[0037] After completing the phased infusion of the inner surface region, the resin matrix of the load-bearing structural layer is infused into the outer surface region and co-cured with the thermal runaway self-evolving barrier layer. The resin matrix of the load-bearing structural layer is selected from at least one of epoxy resin or bismaleimide resin, and the glass transition temperature of the resin matrix is ​​set not lower than 150°C. The co-curing adopts a stepped temperature rise curve, for example, holding at 90°C for 40 min, rising to 150°C and holding for 60 min, then rising to 200°C and holding for 90 min, followed by furnace cooling, so as to integrate the load-bearing structural layer and the thermal runaway self-evolving barrier layer and avoid interface delamination.

[0038] After curing, the sacrificial core material is removed to form a flow channel network, and the precursor of the capture liner is cured and shaped to obtain a capture liner on the inner wall of the flow channel network. When the sacrificial core material is a water-soluble polymer core material, it is dissolved and removed by circulating water or water-based solvent at 40℃ to 90℃ for 10 min to 180 min. When the sacrificial core material is a low-melting-point wax-based core material, it is melted and discharged by heating at 70℃ to 140℃ and flushing with the flow medium. After the sacrificial core material is removed, the capture liner is post-cured at a temperature of 120℃ to 180℃ for 30 min to 180 min to stabilize the thickness and adhesion strength of the capture liner. After completion, the connectivity of the flow channel network is tested by differential pressure. The test differential pressure is set at 5 kPa to 30 kPa and maintained for 60 s to 300 s. If the differential pressure decay meets the set threshold, the flow channel network is considered to be connected and the capture liner has not undergone through-peeling.

[0039] Example 4 like Figure 1-2 As shown, the staged infusion includes curing the first functional area formulation to a pre-gel state before infusion, and curing the second functional area formulation to a pre-gel state before infusion, and infusion of the third functional area formulation. The pre-gel state is the state in which the initial viscosity of the corresponding formulation increases to 2 to 8 times and has not entered the curing exothermic peak when the infusion is completed. The initial viscosities of the first functional zone formulation, the second functional zone formulation, and the third functional zone formulation increase sequentially at 25°C, and are 200 mPa·s to 1500 mPa·s, 400 mPa·s to 2500 mPa·s, and 800 mPa·s to 5000 mPa·s, respectively. The gel times for the first functional area formulation, the second functional area formulation, and the third functional area formulation are 3 min to 15 min, 5 min to 25 min, and 8 min to 40 min, respectively. The infusion sequence, the pre-gel state, and the gel time are coordinated to ensure that the first functional area, the second functional area, and the third functional area are layered sequentially along the thickness direction and maintain interface continuity, while restricting the reverse migration of the phase change material microcapsules, the metal hydroxide endothermic filler or the carbonate endothermic filler, the expanded carbonization system, and the ceramicized filler in the thickness direction. When forming the capture liner precursor, the sacrificial core material is coated at least twice. The first coating is applied to the outer surface of the sacrificial core material to form a base coating layer, which is composed of a high-temperature resistant binder phase precursor and an adsorbent filler. The second coating is applied to the outer surface of the flame-extinguishing section core material to form a reinforcing coating layer, which is composed of a high-temperature resistant binder phase precursor, an adsorbent filler and a ceramicized filler. After the second coating is completed, the capture liner precursor is pre-cured. The pre-curing process is to keep the temperature at 60°C to 120°C for 10 min to 90 min to make the capture liner precursor reach a surface dry state. The thickness of the substrate coating layer is 50 μm to 300 μm, the thickness of the reinforcing coating layer is 50 μm to 400 μm, and the ratio of the thickness of the reinforcing coating layer to the thickness of the substrate coating layer is 1.2 to 3.5; the mass fraction of the ceramicized filler in the reinforcing coating layer is 10% to 55%. In this embodiment, after the fiber preform is arranged and the sacrificial core material is positioned, a capture liner precursor is first prepared on the outer surface of the sacrificial core material and a partitioned reinforcement structure is formed by two coatings. The first step involves preparing a substrate coating slurry. The high-temperature resistant binder precursor is a modified phenolic resin precursor with a solid content of 55% to 65%. The adsorption filler is a composite system of MgO powder and 13X molecular sieve, with MgO having a D50 of 1.0 μm to 2.0 μm and 13X molecular sieve having a D50 of 3.0 μm to 6.0 μm. The mass fraction of the adsorption filler in the substrate coating slurry is set to 70%, and the mass ratio of MgO to 13X molecular sieve is set to 6:4. The high-temperature resistant binder precursor was preheated to 45°C and added in batches with adsorption filler under stirring at 500 rpm. After stirring for 25 min, the substrate coating slurry was obtained by degassing for 10 min. The viscosity of the substrate coating slurry was controlled at 1200 mPa·s to 2200 mPa·s at 25°C. Subsequently, the sacrificial core material was immersed in the substrate coating slurry by dip coating and pulled out at a constant speed of 20 mm / s to 60 mm / s. After being pulled out, the material was allowed to stand and level for 90 s to 240 s. The wet film thickness was controlled by a wet film gauge and the substrate coating layer was obtained after pre-curing. The dry film thickness of the substrate coating layer was controlled at 120 μm to 220 μm.

[0040] The second step involves preparing a reinforcing coating slurry and applying it only to the core material of the folded-back flame-extinguishing section. The high-temperature resistant binder precursor and adsorbent filler system of the reinforcing coating slurry is consistent with that of the base coating slurry. Additionally, a ceramicized filler is added to form a skeleton reinforcement under high-temperature scouring conditions. The ceramicized filler is a composite system of mullite powder and phosphate powder, with the mullite having a D50 of 2.0 μm to 4.0 μm and the phosphate powder having a D50 of 1.0 μm to 3.0 μm. The mass fraction of the ceramicized filler in the reinforcing coating slurry is set at 28%, the mass fraction of the adsorbent filler is set at 52%, and the mass fraction of the high-temperature resistant binder precursor is set at 20%. The viscosity of the strong coating slurry at 25℃ is controlled to be between 1800 mPa·s and 3500 mPa·s. An enhanced coating layer is formed on the outer surface of the core material of the reversible flame-extinguishing section by spraying or scraping. The dry film thickness of the enhanced coating layer is controlled to be between 180 μm and 360 μm, and the ratio of the thickness of the enhanced coating layer to the thickness of the base coating layer is controlled to be between 1.2 and 3.5. After coating, the precursor of the capture liner is pre-cured. The pre-curing temperature is set to 90℃ and the pre-curing time is set to 40 min, so that the precursor of the capture liner reaches the surface dry state. The surface dry state is determined by the scratching method. When the surface is scratched for 10 mm with a scratching force of 0.5 N, no continuous peeling occurs and no glass rod adheres to the surface.

[0041] After the surface drying treatment of the captured liner precursor is completed, staged infusion is performed on the inner surface area to form the first, second, and third functional zones. The layering sequence in the thickness direction is locked through a pre-gel window to inhibit retrograde migration of the filler. The slurry for the first functional zone uses a composite system of phase change material microcapsules and aluminum hydroxide endothermic filler. The phase change material microcapsules have a phase change temperature of 150℃ to 160℃ and a D50 of 15μm to 25μm, while the aluminum hydroxide has a D50 of 1.0μm to 2.0μm. The mass fraction of the phase change material microcapsules is set at 18%, the aluminum hydroxide mass fraction at 32%, and the continuous phase mass fraction of the binding resin at 50%. The initial viscosity of the first functional zone slurry is controlled at 900mPa·s to 1400mPa·s at 25℃, and the gelation time is controlled at 8min to 12min. The slurry for the second functional zone includes an expanded carbonization system, which uses ammonium polyphosphate as the acid source component, pentaerythritol as the carbon source component, and melamine as the... The foaming source component is composed of zinc borate as a synergistic component. The mass fraction of the acid source component is set at 22%, the mass fraction of the carbon source component is set at 10%, the mass fraction of the foaming source component is set at 8%, the mass fraction of the synergistic component is set at 6%, and the mass fraction of the continuous phase of the bonding resin is set at 54%. The initial viscosity of the slurry in the second functional zone is controlled at 1400 mPa·s to 2100 mPa·s at 25°C, and the gel time is controlled at 14 min to 20 min. The slurry in the third functional zone contains ceramicized filler, which is a compound of kaolin and mullite with a small amount of borate flux filler added. The mass fraction of kaolin is set at 18%, the mass fraction of mullite is set at 22%, the mass fraction of borate flux filler is set at 6%, and the mass fraction of the continuous phase of the bonding resin is set at 54%. The initial viscosity of the slurry in the third functional zone is controlled at 2200 mPa·s to 3800 mPa·s at 25°C, and the gel time is controlled at 22 min to 35 min.

[0042] In the staged pouring process, the first functional zone slurry is poured first, and pre-geling control is implemented. The pre-geling state is determined by a dual condition of viscosity ratio and exothermic peak. The viscosity ratio is defined as the system viscosity measured by an online rotational viscometer reaching 4 times but not exceeding 8 times the initial viscosity. The exothermic peak is determined by small-sample differential scanning calorimetry to confirm that the system has not entered the curing exothermic peak region. In this embodiment, after the first functional zone slurry is poured, the mold temperature is set to 60°C and maintained for 6 to 9 minutes to allow the first functional zone slurry to reach the pre-geling state. Then, the second functional zone slurry is poured, and the mold temperature is maintained at 60°C for 8 to 13 minutes to allow the second functional zone slurry to reach the pre-geling state. The third functional zone slurry was injected and overall curing was performed. To ensure the continuity of the layered interface and avoid layer mixing, the injection pressure difference of the second functional zone slurry was set to 8 kPa to 18 kPa, and the injection pressure difference of the third functional zone slurry was set to 10 kPa to 22 kPa. After each injection, the vacuum was maintained for 60 s to 180 s to remove residual air bubbles at the interface. Finally, a stable hierarchical structure with a thickness of 0.30 mm to 0.45 mm in the first functional zone, 0.35 mm to 0.60 mm in the second functional zone, and 0.30 mm to 0.55 mm in the third functional zone was obtained. The width of the three-layer interface transition zone was controlled to be 30 μm to 120 μm and no through-pore zones appeared.

[0043] To verify the supporting effect of the pre-gel window and the double-coating structure on the creative main line, energy dispersive spectroscopy (EDS) and microscopic observation were performed on the cross-section of the molded shell wall. The results showed that the characteristic elemental signals of the microcapsules in the first functional region exhibited a peak distribution near the inner surface and attenuated outwards. The phosphorus signal in the second functional region was mainly concentrated in the middle layer and did not show obvious inward migration at the interface. The silicon and aluminum signal in the third functional region was mainly concentrated in the outer layer, and the diffusion width at the interface of the second functional region did not exceed 120 μm. The thickness of the trapping liner was statistically analyzed, and the trapping layer was located at the buffer expansion section. The liner thickness is 120μm to 220μm, and the capture liner thickness at the back flame extinguishing section is 260μm to 460μm, with a thickness ratio falling within the range of 1.2 to 3.5. The continuous coverage of the ceramicized packing enrichment zone at the back flame extinguishing section is not less than 90%. Under simulated high-temperature gas scouring conditions, 20 pressure pulse impacts are performed, with the pressure pulse peak value set at 25kPa to 35kPa and the gas temperature set at 300℃ to 420℃. No through-peeling occurs in the capture liner at the back flame extinguishing section, and the peak concentration of downstream acidic components is reduced by more than 60% compared to the inlet.

[0044] Example 5 like Figure 1-2 As shown, the step of removing the sacrificial core material to form the flow channel network includes: After the capture liner precursor reaches the surface dry state, the inlet and outlet ends of the sacrificial core material are connected to the guiding medium and a pressure difference is established. The pressure difference is 5 kPa to 30 kPa, so that the capture liner precursor adheres to the outer surface of the sacrificial core material. The sacrificial core material is removed by dissolution or melt removal. The dissolution method involves circulating and rinsing the material with water or a water-based solvent as the guiding medium at a temperature of 40°C to 90°C for 10 to 180 minutes. The melt removal method involves melting the sacrificial core material at a temperature of 70°C to 140°C and removing it with the guiding medium. After the sacrificial core material is removed, the capture liner precursor is subjected to post-curing treatment, which is to maintain the temperature at 120°C to 180°C for 30 min to 180 min to obtain the capture liner and maintain the thickness stability of the base coating and the reinforcing coating. In the step of preparing the fiber preform, a thinning preformed region is formed at a predetermined position adjacent to the flow channel network and located on the inner surface side. The thinning preformed region is obtained by setting the number of fiber lay-up layers at the predetermined position to 0.3 to 0.8 times that of the non-thinning region or setting the fiber areal density at the predetermined position to 0.3 to 0.7 times that of the non-thinning region. Before injecting the load-bearing structural layer resin matrix into the outer surface side region, a peelable flow-limiting membrane is laid on the surface of the thinning preformed region. The peelable flow-limiting membrane is used to limit the excessive penetration of the load-bearing structural layer resin matrix into the thinning preformed region and control the resin enrichment in the thinning preformed region. After co-curing is completed and the peelable flow-limiting membrane is removed, a controllable cracking thin region is formed at the thinning preformed region. The thickness of the controllable cracking thin region is 0.15 mm to 0.80 mm, and the controllable cracking thin region is located on the inner surface side close to the flow channel network. In this embodiment, after the shell wall has been co-cured and the precursor of the capture liner has reached the surface dry state, a controllable pressure difference is first established between the inlet and outlet ends of the sacrificial core material, and the sacrificial core material is removed and the capture liner is shaped. At the same time, a thinning preformed area is constructed on the inner surface side near the inlet of the flow channel network, and a controllable cracking thin area is formed in conjunction with a peelable flow-limiting membrane to ensure that the capture liner is not washed away and peeled off after the flow channel network is formed, and the position and thickness of the controllable cracking thin area are stable.

[0045] Before removing the sacrificial core material, connect the inlet end of the sacrificial core material to the flow medium supply pipeline and the outlet end to the recovery pipeline. The flow medium is deionized water or a water-based solvent. Establish a pressure difference between the inlet and outlet ends, maintaining this difference at 8 kPa to 22 kPa. After establishing the pressure difference, pre-flush for 60 to 180 seconds at a low flow rate of 0.2 L / min to 1.0 L / min. This allows the captured liner precursor to continuously adhere to the outer surface of the sacrificial core material under the pressure difference, eliminating free air bubbles at predetermined locations in the flow channel network. Then, perform sacrificial core material removal. When the sacrificial core material is a water-soluble polymer core material, set the flow medium temperature to 65°C to 85°C and circulate for 20 to 1 minute. During the 60-minute cyclic rinsing process, the pressure difference is maintained at no less than 8 kPa and no more than 22 kPa. At the same time, the changes in conductivity and turbidity of the solution at the outlet are monitored. When the rate of change in conductivity is less than 5% and the turbidity is lower than the set threshold, it is determined that the main body of the sacrificial core material has been removed. When the sacrificial core material is a low-melting-point wax-based core material, the temperature of the guiding medium is set to 90°C to 125°C and cyclic rinsing is performed for 10 to 90 minutes. During the rinsing process, the pressure difference is maintained at 5 kPa to 18 kPa so that the molten core material is discharged with the guiding medium and the captured liner precursor remains stably attached. After the removal is completed, the rinsing is continued with a guiding medium at 40°C to 60°C for 5 to 30 minutes to remove residues and reduce the risk of adhesion to the inner wall surface.

[0046] After the sacrificial core material is removed, the precursor for the capture liner on the inner wall of the flow channel network undergoes post-curing treatment to obtain the capture liner. Post-curing is performed at 120℃ to 180℃ for 30 to 180 minutes. Prior to post-curing, a drying and draining process is conducted by purging the flow channel network with drying gas for 5 to 40 minutes at a pressure difference of 3 kPa to 12 kPa. After post-curing, the connectivity and liner stability of the flow channel network are tested. The connectivity test uses a pressure difference maintenance method, with the test pressure difference set at 10 kPa to 30 kPa. The pressure difference was maintained at kPa for 120s to 600s. The connectivity was deemed qualified if the pressure difference decay met the set threshold. The stability of the liner was tested by sampling the thickness of the inner wall and conducting a scour resistance test. The thickness was measured by ultrasonic thickness measurement or cross-sectional microscopy. The thickness of the capture liner at the flame-extinguishing section was maintained in the range of 260μm to 460μm with a thickness fluctuation of no more than ±15%. The scour resistance test was conducted by gas pulse impact at 300℃ to 420℃ for 20 to 50 times, with a single pulse peak pressure difference of 20kPa to 35kPa. The capture liner was deemed stable if no through-peeling or continuous peeling was observed.

[0047] In the formation of the controllable fracture thin region, during the layup stage of the fiber preform preparation, a thinning preformation zone is formed at a predetermined position on the inner surface adjacent to the inlet of the flow channel network. The thinning preformation zone is achieved by reducing the number of fiber layup layers or the fiber areal density at the predetermined position. For example, the number of layup layers in the thinning preformation zone is set to 0.5 to 0.7 times that of the non-thinning region, and the areal density of the thinning preformation zone is controlled to be 0.4 to 0.6 times that of the non-thinning region. The in-plane dimensions of the thinning preformation zone are set to 20 mm x 20 mm to 80 mm x 120 mm and correspond to the inlet projection area of ​​the buffer expansion section. Before injecting the load-bearing structural layer resin matrix into the outer surface region, a thinning preformation zone is formed on the surface of the thinning preformation zone. A peelable current-limiting membrane is used, which is made of polytetrafluoroethylene film or polyamide film. The film thickness is 20μm to 80μm and covers the entire thinning preformation area with an outer boundary of 2mm to 8mm. The peelable current-limiting membrane is used to limit the excessive penetration of the resin matrix of the load-bearing structural layer into the thinning preformation area and control the resin enrichment in the thinning preformation area. After co-curing, the peelable current-limiting membrane is removed, and a controllable cracking thin area is obtained at the thinning preformation area. The thickness of the controllable cracking thin area is controlled to be 0.30mm to 0.55mm and located on the inner surface side close to the flow channel network. The thickness is detected by a combination of point measurement and in-plane grid measurement. The in-plane grid step size is 5mm to 10mm and the thickness dispersion is no greater than ±0.08mm.

[0048] To verify the coupling effect between the controllable fracture thin region and the inlet of the flow channel network, a combined temperature rise and pressure load was applied to the inner surface. The temperature rise condition involved heating the inner surface to 220℃ to 350℃ and holding it for 5 to 20 minutes. The pressure condition involved superimposing a pressure pulse of 10 kPa to 40 kPa at the inlet of the buffer expansion section and repeating it 10 to 30 times. Under the action of the pressure pulse, the controllable fracture thin region preferentially underwent local cracking to form an air inlet opening, and the opening position was aligned with the inlet of the buffer expansion section. The effective area of ​​the opening stabilized at 0.8 cm². 2 up to 3.5cm 2 Within the range and without disorderly expansion along the non-thinning region, the gas then enters the buffer expansion section and is guided and discharged along the paths of the return flame extinguishing section and the directional emission section. After the test, the capture liner was re-inspected. The continuous coverage of the capture liner at the return flame extinguishing section was not less than 90% and no through-peeling occurred. This indicates that the differential pressure patch additional removal process and the flow-limiting membrane seepage control mechanism can simultaneously ensure the formation stability of the capture liner on the inner wall of the flow channel network and the thickness and position stability of the controllable rupture thin area.

[0049] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0050] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A composite battery casing comprising a fiber-reinforced resin-based composite material forming a casing wall, the casing wall having an inner surface facing a cell cavity and an outer surface opposite to the inner surface, characterized in that: The shell wall includes a load-bearing structural layer along the thickness direction and a thermal runaway self-evolution barrier layer located on the inner surface side and integrally combined with the load-bearing structural layer. The load-bearing structural layer is a continuous fiber reinforced resin matrix composite material layer, and the continuous fiber is at least one of carbon fiber, glass fiber, basalt fiber or aramid fiber. The volume fraction of the continuous fiber is 30% to 70%, and the resin matrix of the supporting structural layer is at least one of epoxy resin, bismaleimide resin or phenolic resin, and the glass transition temperature of the resin matrix is ​​not lower than 150°C. The thickness of the thermal runaway self-evolving barrier layer is 0.2 mm to 2.0 mm, and the thermal runaway self-evolving barrier layer includes a first functional area, a second functional area and a third functional area in sequence along the thickness direction from the side closer to the inner surface to the side closer to the outer surface; The first functional area includes at least one of phase change material microcapsules, metal hydroxide endothermic fillers, or carbonate endothermic fillers, and undergoes phase change endothermic or decomposition endothermic at a temperature of 120°C to 200°C. The second functional area includes an expanded carbonization system, which is composed of an acid source component, a carbon source component and a foaming source component, and forms a continuous carbonized heat insulation layer at a temperature of 220°C to 350°C. The third functional area includes ceramicized filler, which is at least one of silicate, borate, aluminosilicate or phosphate ceramicized filler, and forms a dense ceramicized barrier layer at a temperature not lower than 650°C.

2. The composite material battery casing according to claim 1, characterized in that, The shell wall also includes a flow guiding cavity network disposed between the supporting structure layer and the thermal runaway self-evolution barrier layer or disposed inside the supporting structure layer. The flow guiding cavity network extends along the thickness direction or in-plane direction of the shell wall and forms a connected gas discharge path. The inner wall of the flow guiding cavity network is provided with a capture liner, which includes a high-temperature resistant binder phase and an adsorption filler dispersed in the high-temperature resistant binder phase. The adsorption filler is at least one of metal oxide adsorption filler, molecular sieve adsorption filler or alkaline inorganic salt adsorption filler, so as to adsorb and capture acidic components and water vapor in the thermal runaway gas. The thickness of the capture liner is from 50 μm to 500 μm, and the mass fraction of the adsorbent filler in the capture liner is from 30% to 85%.

3. A composite material battery casing according to claim 2, characterized in that, The flow channel network includes a buffer expansion section, a reversing flame extinguishing section, and a directional emission section connected in sequence; The equivalent volume of the buffer expansion section is greater than the equivalent volume of the deflection flame extinguishing section. The deflection flame extinguishing section includes at least two deflection channels and a porous flame arrestor disposed in the deflection channels. The porous flame arrestor is composed of an inorganic skeleton phase and a connecting hole structure. The pore size of the connecting hole structure is 0.2 mm to 2.0 mm. The inorganic skeleton phase includes at least one of the ceramicized fillers. The thickness of the capture liner at the folding flame extinguishing section is greater than the thickness of the capture liner at the buffer expansion section, and the capture liner at the folding flame extinguishing section further includes at least one of the ceramicized fillers; The shell wall also has a controllable fracture thin zone on the inner surface side near the flow channel network. The controllable fracture thin zone is made of locally thinned fiber-reinforced resin matrix composite material. The thickness of the controllable fracture thin zone is 0.15 mm to 0.80 mm, so that the gas in the thermal runaway state preferentially enters the deflection flame extinguishing section through the flow channel network and is discharged through the directional emission section.

4. A manufacturing process for a composite material battery casing, based on the composite material battery casing according to claims 1-3, characterized in that, Includes the following steps: A fiber preform is prepared and an inner surface region and an outer surface region facing the cell cavity are defined in the fiber preform. The inner surface region is used to form a thermal runaway self-evolving barrier layer, and the outer surface region is used to form a load-bearing structural layer. The fiber preform is arranged with sacrificial core materials and the sacrificial core materials are arranged to form a network of flow guiding cavities. The sacrificial core materials include a buffer expansion section core material, a reversing flame extinguishing section core material and a directional emission section core material that are connected in sequence. A trapping liner precursor is formed on the outer surface of the sacrificial core material. The trapping liner precursor includes a high-temperature resistant binder phase precursor and an adsorbent filler. Furthermore, ceramic filler is enriched on the outer surface of the corresponding folded-back flame-extinguishing section core material. A thermal runaway self-evolving barrier layer is formed by multi-stage infusion and curing into the inner surface side region. The multi-stage infusion is used to form a first functional region, a second functional region, and a third functional region in the inner surface side region. The multi-stage infusion includes sequentially infusing the first functional region formulation, the second functional region formulation, and the third functional region formulation. The first functional region formulation contains at least one of phase change material microcapsules, metal hydroxide endothermic fillers, or carbonate endothermic fillers. The second functional region formulation contains an expanded carbonization system composed of an acid source component, a carbon source component, and a foaming source component. The third functional region formulation contains at least one of ceramicized fillers. The infusion order and gelation time window of the first functional region formulation, the second functional region formulation, and the third functional region formulation are set to ensure that the first functional region, the second functional region, and the third functional region are sequentially layered along the thickness direction and maintain interface continuity. The supporting structural layer resin matrix is ​​injected into the outer surface side region and co-cured with the thermal runaway self-evolving barrier layer, so that the supporting structural layer and the thermal runaway self-evolving barrier layer are integrated and bonded together. After curing, the sacrificial core material is removed to form a flow channel network, and the capture liner precursor is cured and shaped to obtain a capture liner on the inner wall of the flow channel network.

5. The manufacturing process of a composite material battery casing according to claim 4, characterized in that, The staged infusion includes curing the first functional area formulation to a pre-gel state before infusion, and curing the second functional area formulation to a pre-gel state before infusion, and curing the second functional area formulation to a pre-gel state before infusion, wherein the pre-gel state is the state in which the initial viscosity of the corresponding formulation increases to 2 to 8 times and has not entered the curing exothermic peak when infusion is completed. The initial viscosities of the first functional zone formulation, the second functional zone formulation, and the third functional zone formulation increase sequentially at 25°C, and are 200 mPa·s to 1500 mPa·s, 400 mPa·s to 2500 mPa·s, and 800 mPa·s to 5000 mPa·s, respectively. The gel times for the first functional area formulation, the second functional area formulation, and the third functional area formulation are 3 min to 15 min, 5 min to 25 min, and 8 min to 40 min, respectively. The infusion sequence, the pre-gel state, and the gelation time are coordinated to ensure that the first functional region, the second functional region, and the third functional region are sequentially layered along the thickness direction and maintain interface continuity, while restricting the reverse migration of the phase change material microcapsules, the metal hydroxide endothermic filler or the carbonate endothermic filler, the expanded carbonization system, and the ceramicized filler in the thickness direction.

6. The manufacturing process of a composite material battery casing according to claim 5, characterized in that, When forming the capture liner precursor, the sacrificial core material is coated at least twice. The first coating is applied to the outer surface of the sacrificial core material to form a base coating layer, which is composed of a high-temperature resistant binder phase precursor and an adsorbent filler. The second coating is applied to the outer surface of the flame-extinguishing section core material to form a reinforcing coating layer, which is composed of a high-temperature resistant binder phase precursor, an adsorbent filler and a ceramicized filler. After the second coating is completed, the capture liner precursor is pre-cured. The pre-curing process is to keep the temperature at 60°C to 120°C for 10 min to 90 min to make the capture liner precursor reach a surface dry state. The thickness of the substrate coating layer is 50 μm to 300 μm, the thickness of the reinforcing coating layer is 50 μm to 400 μm, and the ratio of the thickness of the reinforcing coating layer to the thickness of the substrate coating layer is 1.2 to 3.5; the mass fraction of the ceramicized filler in the reinforcing coating layer is 10% to 55%.

7. The manufacturing process of a composite material battery casing according to claim 6, characterized in that, The steps of removing the sacrificial core material to form the flow channel network include: After the capture liner precursor reaches the surface dry state, the inlet and outlet ends of the sacrificial core material are connected to the guiding medium and a pressure difference is established. The pressure difference is 5 kPa to 30 kPa, so that the capture liner precursor adheres to the outer surface of the sacrificial core material. The sacrificial core material is removed by dissolution or melt removal. The dissolution method involves circulating and rinsing the material with water or a water-based solvent as the guiding medium at a temperature of 40°C to 90°C for 10 to 180 minutes. The melt removal method involves melting the sacrificial core material at a temperature of 70°C to 140°C and removing it with the guiding medium. After the sacrificial core material is removed, the capture liner precursor is subjected to a post-curing treatment, which is to maintain the temperature at 120°C to 180°C for 30 min to 180 min to obtain the capture liner and maintain the thickness stability of the base coating and the reinforcing coating.

8. The manufacturing process of a composite material battery casing according to claim 7, characterized in that, In the step of preparing the fiber preform, a thinning preformed region is formed at a predetermined position adjacent to the flow channel network and located in the inner surface region. The thinning preformed region is obtained by setting the number of fiber lay-up layers at the predetermined position to 0.3 to 0.8 times that of the non-thinning region or setting the fiber areal density at the predetermined position to 0.3 to 0.7 times that of the non-thinning region. Before injecting the load-bearing structural layer resin matrix into the outer surface region, a peelable flow-limiting membrane is laid on the surface of the thinning preformed region. The peelable flow-limiting membrane is used to limit the excessive penetration of the load-bearing structural layer resin matrix into the thinning preformed region and control the resin enrichment in the thinning preformed region. After co-curing is completed and the peelable flow-limiting membrane is removed, a controllable cracking thin region is formed in the thinning preformed area. The thickness of the controllable cracking thin region is 0.15 mm to 0.80 mm, and the controllable cracking thin region is located on the inner surface side close to the flow channel network.

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