An embedded structure battery and its fabrication method

Abstract

This invention discloses an embedded structure battery and its fabrication method. The fabrication method includes the following steps: arranging N layers of mesh fabric in a layered structure, forming through holes at the center for placing energy storage units to obtain a core layer; placing energy storage units into the through holes of the core layer to obtain a core layer structure; placing an upper skin on the upper surface of the core layer structure and a lower skin on the lower surface of the core layer structure to obtain a preform of the structure battery. Both the upper and lower skins include: a stretched fabric; impregnating the preform of the structure battery with a resin system using a vacuum-assisted resin transfer molding process, and curing to obtain the embedded structure battery. The stretched fabric has good interlayer shear properties, and the internal pores of the mesh fabric can dissipate energy through fiber sliding and pore compression. The stretched fabric and the mesh fabric work together to provide energy absorption, thereby protecting the energy storage units inside the core layer and improving the damage tolerance of the embedded structure battery.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to an embedded structure battery and its preparation method. Background Technology

[0002] Embedded structure batteries use pouch cells as the core energy storage unit, which are directly embedded into carbon fiber composite laminates and then integrally formed using vacuum curing. This embedded structure battery organically combines the mechanical properties of composite materials with the energy storage function of the battery, effectively improving the energy efficiency and space utilization efficiency of the energy storage unit. This integration method is simple to manufacture and easy to industrialize, providing an effective way to achieve structural and functional integration while also optimizing system lightweighting and spatial layout.

[0003] However, in practical applications, embedded structure batteries are often exposed to complex impact environments (such as road stone impacts, vehicle collisions, etc.), which can easily cause external damage to the embedded structure battery. At the same time, under the combined load of "impact-continuous compression", the load-bearing capacity of the composite material in the embedded structure battery will inevitably decrease further, ultimately leading to the failure of the entire embedded structure battery pack.

[0004] For example, in existing technologies, researchers such as PATTARAKUNNAN K et al. (PATTARAKUNNAN K, GALOS J, DAS R, Mouritz AP Impact damage tolerance of energy storage composite structures containing lithium-ion polymer batteries, Composite Structures, 2021, 267: 113845) used carbon fiber plain weave fabric and PVC foam as raw materials, and employed wet hand lay-up molding and vacuum bagging processes to prepare carbon fiber structure batteries with foam sandwich structures, and conducted a systematic study on their impact damage tolerance. Specifically, after being subjected to an impact energy of 4J, the compressive strength of the carbon fiber structure battery was 21.1MPa; when the impact energy was 6J, the surface and core layers of the carbon fiber structure battery cracked and broke, leading to a short circuit. Wang et al. (Wang XC, Lu MH, Wang YM, Shang YX, Lei ZK, Bai RX Experimentalstudy on post-impact loading of composite sandwich-structured batteries, Optics and Laser Technology. 2025;186: 112637.) prepared a composite sandwich-structured battery (i.e., an embedded structure battery) using carbon fiber plain weave fabric and PMI foam. After being subjected to an impact energy of 4J, the capacity retention rate of the composite sandwich-structured battery was 84.73%, and its compressive strength after impact compression was 17.78MPa. The capacity retention rate of the composite sandwich-structured battery after impact compression was 2.22%. When the impact energy was 8J, the composite sandwich-structured battery experienced a short circuit after impact. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for fabricating an embedded structure battery with damage tolerance. This method is designed for energy storage units with a height of 4 mm and integrates the energy storage unit, upper skin, lower skin, and core layer into a single unit.

[0006] Another object of the present invention is to provide an embedded structure battery obtained by the above preparation method.

[0007] The objective of this invention is achieved through the following technical solution.

[0008] A method for fabricating an embedded structure battery includes the following steps:

[0009] Step 1): Arrange N layers of mesh fabric in a layered structure, and form a through-hole at the center of each layer to hold an energy storage unit, thus obtaining the core layer. Place the energy storage unit into the through-hole of the core layer to obtain the core layer structure. Here, N = 15~72, and the weight of each layer of mesh fabric is 10~60 g / m². 2 The thickness of each layer of mesh fabric is 0.08~0.4mm, and the thickness of the core layer is at least 5.5mm; the energy storage unit includes: a soft-pack battery cell with a thickness of 4mm, and one end of a wire is connected to the positive and negative tabs of the soft-pack battery cell.

[0010] In step 1), the material of the stretched fabric includes one or more of carbon fiber, aramid fiber and basalt.

[0011] In step 1), N = 65~72, and the weight of each layer of mesh fabric is 10~20 g / m². 2 The thickness of each layer of mesh fabric is 0.08~0.15mm.

[0012] In step 1), the material of the mesh fabric includes one or more of carbon fiber, aramid fiber and basalt.

[0013] In the above technical solution, when the material of the expanded fabric is carbon fiber, the number of fiber bundles constituting the expanded fabric is 12~24K.

[0014] In step 1), the pouch cell is one of the following: wound pouch cell, laminated pouch cell, and laminated composite pouch cell.

[0015] Step 2) Place an upper skin on the upper surface of the core structure and a lower skin on the lower surface of the core structure to obtain a structural battery preform, so that the other ends of the two wires extend out of the structural battery preform. The upper skin and the lower skin each include: 10 to 12 layers of spread fabric arranged in layers, the thickness of the spread fabric is 0.08 to 0.1 mm, the spread fabric is plain weave, and the grid width of the spread fabric is 8 to 20 mm.

[0016] Step 3) The resin system is impregnated onto the preform of the structural battery using a vacuum-assisted resin transfer molding process and cured to form a cured resin product, thereby obtaining an embedded structural battery. The thickness of the N-layer mesh fabric is compressed to 4 mm during the vacuum-assisted resin transfer molding process. The resin system includes resin and curing agent.

[0017] In step 3), the curing temperature is 20~50℃ and the curing time is 1~24h.

[0018] In step 3), the resin is a polyimide resin and / or an epoxy resin.

[0019] In the above technical solution, the viscosity of the resin system is 150~300 mPa·s.

[0020] In the above technical solution, the curing agent is a phenolic amine curing agent, and the ratio of the resin to the curing agent by mass is (2.5~3.5):1.

[0021] In the above technical solution, the pressure of the vacuum environment in the vacuum-assisted resin transfer molding process is -0.1 to -0.08 MPa.

[0022] The embedded structure battery obtained by the above preparation method.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. The embedded structure battery of the present invention uses a widened fabric with few interlacing points and low fiber bundle curling frequency to form the upper and lower skins, and a mesh fabric containing a large number of micron-sized pores as the core layer. The energy storage unit is placed in the core layer to obtain a prefabricated structure battery, which is then impregnated with a resin system to obtain the embedded structure battery. The widened fabric has good interlaminar shear properties, and the internal pores of the mesh fabric can dissipate energy through fiber sliding and pore compression. The widened fabric and the mesh fabric work together to provide energy absorption, thereby protecting the energy storage unit inside the core layer and improving the damage tolerance of the embedded structure battery.

[0025] 2. The embedded structure battery of the present invention has a more compact and simpler structure, effectively saving space and weight, and significantly reducing costs. Attached Figure Description

[0026] Figure 1 The figures are a top view and a cross-sectional outline view of the embedded structure battery in Example 1, where a is the top view and b is the cross-sectional outline view of the middle position.

[0027] Figure 2 The diagram shows a structural schematic of the prefabricated structure battery in the embedded structure battery of the present invention (with the upper skin) and a structural schematic of the prefabricated structure battery after the upper skin is removed, wherein a is a structural schematic (with the upper skin) and b is a structural schematic of the prefabricated structure battery after the upper skin is removed.

[0028] Figure 3 Capacity-voltage diagrams for lithium-ion batteries and the embedded structure battery of Example 1;

[0029] Figure 4The percentage of discharge capacity is the result of 50 cycles of testing on the embedded structure battery of Example 1 and the embedded structure battery after impact (impact energy of 6.7J).

[0030] Figure 5 The percentage of discharge capacity is the result of 50 cycles of testing on the embedded structure battery of Example 1 and the embedded structure battery after impact (impact energy of 10J).

[0031] Figure 6 The percentage of discharge capacity is the result of 50 cycles of testing on the embedded structure battery of Example 1 and the embedded structure battery after impact (impact energy of 13.4J).

[0032] Figure 7 The stress-strain curve is shown for the embedded structure battery in Example 1 (impact energy is 6.7J).

[0033] Figure 8 The stress-strain curve for the embedded structure battery in Example 2 (impact energy is 6.7J).

[0034] Figure 9 The stress-strain curve for the embedded structure battery in Example 3 (impact energy is 6.7J).

[0035] Figure 10 A photograph of the actual battery with an embedded structure after impact compression (impact energy of 13.4J) of Example 1;

[0036] Figure 11 The percentage of discharge capacity after 50 cycles of testing of the impact-embedded structure battery and the impact-compression embedded structure battery (impact energy of 6.7J) of Example 1.

[0037] Figure 12 The percentage of discharge capacity is the result of 50 cycles of testing on the post-impact embedded structure battery and the post-impact compression embedded structure battery (impact energy of 10J) of Example 1.

[0038] Among them, 1: upper skin, 2: core layer, 3: energy storage unit, and 4: lower skin. Detailed Implementation

[0039] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0040] The sources of materials used in the following embodiments:

[0041] Spread fabric: T700 12K carbon fiber spread fabric (the number of fiber bundles that make up the spread fabric is 12K, and the material of the spread fabric is carbon fiber), plain weave, purchased from Tianjin Anglin Maofeng High-tech Materials Co., Ltd., the grid width of the carbon fiber spread fabric is 20mm and the thickness is 0.08mm.

[0042] Net fabric: Carbon fiber net fabric, purchased from Shangwei (Jiangsu) Carbon Fiber Composite Materials Co., Ltd. The material of the net fabric is carbon fiber, and the length of the carbon fiber is 6~7mm.

[0043] Soft-pack battery cell (lithium-ion battery): Purchased from Shenzhen Grepow Battery Co., Ltd. It is a stacked soft-pack battery cell with dimensions of 5cm (length) × 3cm (width) × 4mm (thickness). The soft-pack battery cell uses a lithium cobalt oxide (LiCoO2) / graphite system, with a nominal capacity of 500mAh, a nominal voltage of 3.7V, and an operating voltage range of 3.0~4.2V. It is packaged in an aluminum-plastic film bag.

[0044] Conductor: Outer diameter (including insulation) 1.8mm, conductor cross-sectional area 0.5mm² 2 Purchased from Shanghai Mingxiang Wire & Cable Co., Ltd.

[0045] In the following embodiments, the method for electrical performance cycling testing includes: performing 50 charge-discharge cycle tests on the embedded structure battery using a Landian cycle life testing system (model CT3004A, purchased from Wuhan Landian Electronics Co., Ltd.). Each cycle test includes: constant current-constant voltage charging (with a cutoff current of 0.1C during the constant voltage phase) and constant current discharging within a voltage range of 3.0~4.2V. The discharge capacity percentage for each cycle and the capacity retention rate for the 50th cycle are calculated based on the results of the electrical performance cycling tests.

[0046] The percentage of discharge capacity in the i-th cycle test = the discharge capacity in the i-th cycle test / the nominal capacity of the pouch cell (i is an integer between 1 and 50).

[0047] The capacity retention rate of the 50th cycle test = the discharge capacity of the 50th cycle test / the initial discharge capacity.

[0048] Examples 1-3 and Comparative Example 1

[0049] An embedded structure battery, the preparation method of which includes the following steps:

[0050] Step 1): Arrange N layers of mesh fabric (15cm x 10cm wide) in a layered structure, and then cut a through hole (rectangular cross-section, 5cm x 3cm) at the center to place the energy storage unit 3, thus obtaining the core layer 2. Place the energy storage unit into the through hole of the core layer to obtain the core layer structure. The basis weight of each layer of mesh fabric is X g / m³. 2 The thickness of each layer of mesh fabric is Y mm; the energy storage unit includes: a soft-pack battery cell with a thickness of 4 mm, and one end of a wire is connected to the positive and negative tabs of the soft-pack battery cell.

[0051] Step 2): Place the upper skin 1 on the upper surface of the core structure and the lower skin 4 on the lower surface of the core structure, resulting in the following... Figure 2 The structural battery preform shown has the other ends of two wires passing through the core layer and the upper skin respectively, extending out of the structural battery preform. The upper skin and the lower skin each include 12 layers of spread fabric (15cm long × 10cm wide) arranged in layers.

[0052] Step 3) The resin system is impregnated onto the structural battery preform using a vacuum-assisted resin transfer molding process, and cured at 50°C for 5 hours to allow the resin system to form a cured resin product, resulting in an embedded structural battery blank. Excess cured resin around the embedded structural battery blank is then cut off to obtain the desired product. Figure 1 The embedded battery structure shown has an N-layer mesh fabric whose thickness is compressed to 4 mm during a vacuum-assisted resin transfer molding process. The resin system includes resin and curing agent (692K B, a phenolic amine curing agent, purchased from Shenzhen Langbowan Advanced Materials Co., Ltd.). The resin is epoxy resin (model NO.1-692K-2, purchased from Shenzhen Langbowan Advanced Materials Co., Ltd., with a viscosity of 5500±500 mPa·s). The method for obtaining the resin system includes mixing and stirring the resin and curing agent under normal pressure for 20 minutes, followed by vacuum degassing for 30 minutes. The resin to curing agent ratio is 3:1 by mass, and the viscosity of the resin system is 200±50 mPa·s.

[0053] The vacuum-assisted resin transfer molding process includes: placing the structural battery preform in a closed space (the closed space is slightly larger than the structural battery preform), then evacuating the closed space to a pressure of -0.1MPa (under negative pressure, the thickness of the N-layer mesh fabric is compressed to 4mm); keeping the pressure (-0.1MPa) constant, introducing the resin system into the closed space at a flow rate of 30mL / min, so that the resin system fully impregnates the structural battery preform.

[0054] X, Y, and N are shown in Table 1.

[0055] The dimensions of the embedded structure batteries obtained in Examples 1-3 and Comparative Example 1 are all 15cm×10cm×6mm.

[0056] Table 1

[0057]

[0058] Depend on Figure 1 As can be seen from point a, the surface of the embedded battery structure is smooth and flat, and the soft-pack battery corresponds to the position in the box, completely covered by the upper skin 1. Figure 1 As shown in b (the profile was obtained by a surface profilometer), the upper and lower skins are tightly bonded to the core layer, with no obvious gaps, warping, or interface peeling, which proves the feasibility and process adaptability of the embedded structure battery design of this invention.

[0059] Performance tests were conducted on the lithium-ion battery (i.e., pouch cell) and the embedded structure battery of Example 1. The test conditions were as follows: the batteries were placed on a Blue Electric cycle life testing system, using a 1C constant current-constant voltage (CCCV) scheme, with a voltage range of 3.0~4.2V and a cutoff current of 0.1C. The batteries were either lithium-ion batteries or the embedded structure battery of Example 1. The capacity-voltage diagrams obtained for the lithium-ion battery and the embedded structure battery of Example 1 are shown below. Figure 3 As shown. By Figure 3 It can be seen that, compared with lithium-ion batteries, the embedded structure battery of Example 1 ( Figure 3 The output voltage and capacity of the "structural battery" in Example 1 remained essentially unchanged. This indicates that the capacity of the embedded structural battery in Example 1 did not experience a performance degradation due to the structural change (if a performance degradation occurred: Figure 3 The curve for the "structured battery" will shift to the left, indicating a decrease in capacity. This demonstrates that the embedded structured battery, using expanded fabric as the skin (upper and lower skins), a mesh fabric as the core layer, and a through-hole design, can provide a suitable mounting carrier for the pouch cell and avoid damage to the active material, positive tab, and negative tab connection of the pouch cell during the structural molding process, highlighting the rationality and feasibility of the structural design.

[0060] Example 4

[0061] The embedded structure battery of Example 1 was subjected to electrical performance cycling tests, and the discharge capacity percentage after 50 cycles was obtained, as follows: Figures 4-6 "10g / m" 2 - As shown in "Before the impact".

[0062] Example 5

[0063] An impact test was performed on the embedded structure battery to obtain an impact-compressed embedded structure battery. The impact-compressed embedded structure battery was then subjected to a cyclic electrical performance test. Next, a compression test was performed on the impact-compressed embedded structure battery to obtain an impact-compressed embedded structure battery. The impact-compressed embedded structure battery was then subjected to a cyclic electrical performance test. The embedded structure battery is one of Examples 1-3 and Comparative Example 1.

[0064] The impact test method referenced "ASTM D7136-D7136M-20 Standard Test Method for Measuring the Resistance of Fiber-Reinforced Polymer Matrix Composites to Drop Hammer Impact Damage," specifically as follows: An Instron 9250 drop hammer impact testing machine (purchased from Instron (Shanghai) Test Equipment Trading Co., Ltd.) was used to impact the embedded battery structure. A hemispherical steel bullet impact head with a diameter of 12.7 mm and a mass of 7.171 kg was selected. The impact velocities were 1.37 m / s, 1.67 m / s, or 1.93 m / s. At an impact velocity of 1.37 m / s, the impact energy was 6.7 J; at 1.67 m / s, the impact energy was 10 J; and at 1.93 m / s, the impact energy was 13.4 J. An impact energy of 6.7J is used to simulate minor impact conditions (such as daily bumps and minor collisions), an impact energy of 10J is used to simulate moderate impact conditions, and an impact energy of 13.4J is used to simulate severe impact conditions (such as being hit by a heavy object).

[0065] The compression test was conducted according to "ASTM D7137-D7137M-23 Standard Test Method for Compressive Residual Strength Characteristics of Damaged Polymer Composite Panels". The impact-embedded structure battery was used as the "Specimen" in "8. Sampling and Test Samples" of "ASTM D7137-D7137M-23 Standard Test Method for Compressive Residual Strength Characteristics of Damaged Polymer Composite Panels". During compression, the lower clamp of the electronic universal testing machine (TSE105D model, purchased from Shenzhen Wanchuang Testing Equipment Co., Ltd.) was fixed, and the upper clamp moved downwards at a rate of 0.5 mm / min to compress the material. The stress-strain curve was obtained, and the compressive strength was calculated based on the stress-strain curve. The compressive strength is shown in Table 2.

[0066] Cyclic electrical performance tests were performed on the embedded structure battery after impact to simulate the electrical performance under a single operating condition (impact load only), and cyclic electrical performance tests were performed on the embedded structure battery after impact compression to simulate the electrical performance under a complex operating condition ("impact-compression", combined load).

[0067] Single operating condition analysis:

[0068] Table 2 shows the capacity retention rates of the embedded structure batteries in Examples 1-3 and Comparative Example 1 after the 50th cycle test following the impact.

[0069] When the impact energy is 6.7J, the discharge capacity percentage of the embedded structure battery in Example 1 after the impact is as follows: Figure 4 "10g / m" 2 As shown in the image, "After a -6.7J impact"; by Figure 4 It can be seen that after an impact energy of 6.7J, its discharge capacity percentage is different from that before the impact. Figure 4 "10g / m" 2 The electrical performance remained largely consistent with that before the impact, with no significant attenuation, fluctuations, or sudden drops, indicating that the embedded structure battery of Example 1 exhibits excellent electrical performance stability under a single operating condition of slight impact. This is attributed to the synergistic absorption of impact energy by the skin (upper and lower skins) and the core layer in the embedded structure battery, effectively suppressing the transmission of impact stress into the pouch cell, thereby avoiding problems such as short circuits and active material shedding within the pouch cell, fully demonstrating the optimized effect of "electrical performance damage tolerance".

[0070] When the impact energy is 10J, the discharge capacity percentage of the embedded structure battery in Example 1 after the impact is as follows: Figure 5 "10g / m" 2 "After a -10J impact", by Figure 5 It can be seen that after being impacted by 10J energy, the soft-pack battery cell did not experience internal short circuits or loss of active material, demonstrating excellent electrical performance.

[0071] When the impact energy is 13.4 J, the percentage of discharge capacity of the embedded structure battery in Example 1 after the impact is as follows: Figure 6 "10g / m" 2 "After a -13.4J impact." Figure 6 It can be seen that after an impact energy of 13.4J, the embedded structure battery did not suffer overall structural failure (such as core layer collapse or battery rupture) and can still maintain more than 90% of its energy storage capacity.

[0072] After being subjected to an impact energy of 13.4 J, the embedded structure battery in Comparative Example 1 exhibited a capacity retention of 0%. At this point, the embedded structure battery in Comparative Example 1 experienced a short circuit and a sharp drop in structural mechanical properties, indicating complete failure. Comparative data shows that the basis weight and thickness of the single-layer mesh fabric play a crucial role in controlling the impact resistance and electrical stability of the embedded structure battery.

[0073] Table 2

[0074]

[0075] Complex operating condition analysis:

[0076] The stress-strain curve of the embedded structure battery (impact energy 6.7 J) in Example 1 is as follows: Figure 7 As shown, by Figure 7 It can be seen that when the strain range is 0~2.0%, a typical "elastic growth-plastic strengthening-failure" process is exhibited. Specifically, when the strain < 1.0%, the stress increases approximately linearly with the strain, reflecting the elastic deformation capability of the embedded structure battery. This indicates that after being impacted by 6.7J of impact energy, the main body of the composite material composed of the stretched fabric and the mesh fabric still maintains good structural integrity. When the strain > 1.0%, the stress growth rate accelerates significantly, entering the plastic strengthening stage. After reaching the peak stress, the curve drops sharply, indicating that failure occurs after reaching the compressive strength limit. After being impacted by 6.7J of impact energy, the embedded structure battery of Example 1 can still maintain a compressive strength of 64.791MPa. The mechanical load-bearing capacity of the main body of the composite material in the embedded structure battery is not significantly reduced due to the impact, indicating that it has a damage tolerance advantage under impact conditions. This intuitively reflects the mechanical response characteristics of the embedded structure battery of Example 1 under complex working conditions. This shows that the embedded structure battery of the present invention effectively disperses the impact stress and inhibits the propagation of damage inside the structure. The stress-strain curve of the embedded structure battery (impact energy 6.7 J) in Example 2 is shown below. Figure 8 As shown, the stress-strain curve of the embedded structure battery (impact energy of 6.7 J) in Example 3 is as follows: Figure 9 As shown. Figures 7-9 The system presents the compressive stress-strain response characteristics of the embedded structure battery of the present invention under compressive load, with core layers composed of mesh fabric of different basis weights and thicknesses. The obtained stress-strain curves all exhibit typical compressive mechanical behavior of "elastic growth-yield strengthening-failure". This indicates that after being subjected to an impact energy of 6.7J, the core layers of different areal densities (basis weight and thickness) did not collapse as a whole and still have complete mechanical load-bearing capacity.

[0077] The capacity retention rate of the post-impact compression embedded structure battery (impact energy of 6.7J) in Example 1 was 98.11% after the 50th cycle test, and the capacity retention rate of the post-impact compression embedded structure battery (impact energy of 10J) in Example 1 was 97.49% after the 50th cycle test.

[0078] The capacity retention rate of the post-impact compression embedded structure battery (impact energy of 6.7J) in Example 2 was 94.11% after the 50th cycle test, and the capacity retention rate of the post-impact compression embedded structure battery (impact energy of 10J) in Example 2 was 80.07% after the 50th cycle test.

[0079] The capacity retention rate of the post-impact compression embedded structure battery (impact energy of 6.7J) in Example 3 was 90.98% after the 50th cycle test, and the capacity retention rate of the post-impact compression embedded structure battery (impact energy of 10J) in Example 3 was 56.62% after the 50th cycle test.

[0080] Figure 10 This is a photograph of the impact-compression embedded structure battery (impact energy 13.4 J) of Example 1. Figure 10 It can be seen that the embedded structure battery of Embodiment 1 of the present invention, after being subjected to an impact energy of 13.4J, exhibits the following characteristics under the action of compressive load: no obvious gaps or interface delamination on the surface, effectively protecting the core function of the energy storage unit.

[0081] The discharge capacity percentage of the embedded structure battery (impact energy of 6.7J) after impact in Example 1 is as follows: Figure 11 "10g / m" 2 As shown in the figure, the discharge capacity percentage of the compressed embedded structure battery (impact energy of 6.7J) of Example 1 after impact is as follows: Figure 11 "10g / m" 2 The discharge capacity percentage of the embedded structure battery (impact energy of 10J) after impact is shown in the figure. (The figure is incomplete and requires further context to be accurately translated.) Figure 12 "10g / m" 2 As shown in the figure, the discharge capacity percentage of the compressed embedded structure battery (impact energy of 10J) in Example 1 after impact is as follows: Figure 12 "10g / m" 2 As shown in the figure, "Compression after -10J impact". Figure 11 and Figure 12 Further verification of the embedded structure battery in Example 1 demonstrates its comprehensive damage tolerance: it can withstand not only a single impact load, but also maintain its core energy storage performance when subjected to compressive loads after an impact. This indicates that the mechanical cushioning properties of the stretched fabric in the embedded structure battery effectively suppress structural delamination or battery damage caused by compression after an impact, meeting the usage requirements of complex operating conditions in practical applications and significantly improving reliability and service life.

[0082] Comparative Example 2

[0083] A carbon fiber structure battery with a foam sandwich structure is described in Table 1 of the paper "Impact damage tolerance of energy storage composite structures containing lithium-ion polymer batteries, PATTARAKUNNAN K, GALOS J, DAS R, Mouritz AP, Composite Structures, 2021, 267: 113845" as a "sandwich composite material structure battery". The carbon fiber structure battery has dimensions of 15cm × 10cm × 5.5mm.

[0084] The carbon fiber structure battery in Comparative Example 2 exhibited 0% capacity retention after compression following a 6J impact, at which point it experienced a short circuit and completely failed. Its compressive strength under complex operating conditions was 17.9 MPa, significantly lower than that of the embedded structure battery of this invention.

[0085] Comparative Example 3

[0086] A composite sandwich-structured battery, specifically the "Post-Impact Loading Specimen of Composite Sandwich-Structured Batteries" from section "2. Specimen Preparation and Testing" of the paper "Experimental study on post-impactloading of composite sandwich-structured batteries, Wang XC, Lu MH, Wang YM, Shang YX, Lei ZK, Bai RX, Optics and Laser Technology. 2025;186: 112637.", has dimensions of 15cm × 10cm × 4.5mm.

[0087] The composite sandwich structure battery of Comparative Example 3 exhibited a capacity retention of only 2.22% after compression following a 4J impact, and a compressive strength of 17.78 MPa under complex operating conditions. Its performance is significantly lower than that of the embedded structure battery of this invention, further verifying that the embedded structure battery of this invention possesses outstanding high damage tolerance.

[0088] This invention improves damage tolerance (impact resistance and capacity retention) by balancing the basis weight and number of layers of the mesh fabric. The core layer not only enhances the three-dimensional support of the interwoven carbon fibers but also extends the energy transfer path. Simultaneously, it provides ample deformation buffer space, reducing damage to the energy storage cells in the embedded structure battery from localized stress concentration. This indicates that the embedded structure battery of this invention possesses excellent impact resistance and exhibits good damage tolerance.

[0089] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for fabricating an embedded structure battery, characterized in that, Includes the following steps: Step 1): Arrange N layers of mesh fabric in a layered structure, and form a through-hole at the center of each layer to hold an energy storage unit, thus obtaining the core layer. Place the energy storage unit into the through-hole of the core layer to obtain the core layer structure. Here, N=68, and the weight of each layer of mesh fabric is 10g / m². 2 Each layer of the mesh fabric is 0.11 mm thick, and the core layer is at least 5.5 mm thick. The energy storage unit includes a 4 mm thick soft-pack battery cell, with one end of a wire connected to the positive and negative tabs of the soft-pack battery cell. The mesh fabric is made of carbon fiber, and the length of the carbon fiber is 6-7 mm. Step 2) Place an upper skin on the upper surface of the core structure and a lower skin on the lower surface of the core structure to obtain a structural battery preform, so that the other ends of the two wires extend out of the structural battery preform. The upper skin and the lower skin each include: 12 layers of spread fabric arranged in layers, the thickness of the spread fabric is 0.08~0.1mm, the spread fabric is plain weave, the grid width of the spread fabric is 8~20mm, the material of the spread fabric is carbon fiber, and the number of fiber bundles that make up the spread fabric is 12~24K. Step 3) The resin system is impregnated onto the preform of the structural battery using a vacuum-assisted resin transfer molding process and cured to form a cured resin product, thereby obtaining an embedded structural battery. The thickness of the N-layer mesh fabric is compressed to 4 mm during the vacuum-assisted resin transfer molding process. The resin system includes resin and curing agent.

2. The preparation method according to claim 1, characterized in that, In step 1), the pouch cell is one of the following: wound pouch cell, laminated pouch cell, and laminated composite pouch cell.

3. The preparation method according to claim 1, characterized in that, In step 3), the curing temperature is 20~50℃ and the curing time is 1~24h.

4. The preparation method according to claim 1, characterized in that, In step 3), the resin is a polyimide resin and / or an epoxy resin.

5. The preparation method according to claim 1, characterized in that, The viscosity of the resin system is 150~300 mPa·s.

6. The preparation method according to claim 1, characterized in that, The curing agent is a phenolic amine curing agent, and the ratio of the resin to the curing agent by mass is (2.5~3.5):

1.

7. The preparation method according to claim 1, characterized in that, The pressure of the vacuum environment in the vacuum-assisted resin transfer molding process is -0.1 to -0.08 MPa.

8. An embedded structure battery obtained by the preparation method according to any one of claims 1 to 7.

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