Composite material structure battery integrated forming and series-parallel connection preparation method

Abstract

This invention discloses an integrated molding and series-parallel fabrication method for composite material structure batteries, comprising: analyzing the characteristic parameters of the bidirectional extension structure and calibrating the basic process parameters; preparing positive and negative electrode active slurries and coating them to form active regions and achieve functional zoning; coating resin in the strip transition area between the active region and the support region, stacking fabric, and then pre-pressing and hot-pressing with a special fixture to form a dense, sealed, rigid strip; encapsulating the battery core area and injecting leads to obtain a single cell; stacking the cells and inserting a carbon fiber transition layer; connecting the leads in series and parallel as needed to construct the battery core module; laying carbon fiber cloth on the outer layer of the module, and then impregnating and curing the entire structure with resin using vacuum-assisted resin injection technology to obtain an integrated composite material structure battery. This invention achieves bidirectional continuous extension of carbon fiber positive and negative electrodes, improving the structural mechanical continuity, solving the electrolyte leakage problem through quadruple sealing, and flexibly realizing series and parallel connections to meet complex operating conditions.

Description

Technical Field

[0001] This invention relates to the field of composite material structure battery manufacturing technology, specifically to an integrated molding and series-parallel connection method for composite material structure batteries. Background Technology

[0002] With the rapid development of industries such as low-altitude economic equipment, new energy vehicles, and smart wearable devices, the requirements for the energy storage capacity of structural components are increasing. In traditional structural designs, the load-bearing structure and the energy storage battery are independent, especially since the battery weight often accounts for more than 20% of the total structural weight, making it difficult to further improve the structure's efficiency. To optimize structural efficiency, multifunctional structural batteries have emerged. This innovative solution combines energy storage functions with mechanical load-bearing characteristics, and batteries with both energy storage and load-bearing capabilities are called structural batteries. Among them, carbon fiber stands out due to its excellent mechanical strength, lightweight properties, and natural conductivity. Combined with lithium battery technology, it has become one of the best solutions in the field of structural batteries.

[0003] Carbon fiber structured batteries are mainly divided into two categories: one integrates traditional thin-film batteries into carbon fiber polymer composite materials to form a multifunctional structure with certain rigidity and strength; the other directly uses carbon fiber as a current collector or even an active positive and negative electrode, enabling carbon fiber to possess both electrochemical and mechanical load-bearing properties. The second approach can more fully utilize the multifunctional characteristics of structural batteries. Currently, researchers have conducted extensive research on carbon fiber as a positive and negative electrode current collector, typically coating the carbon fiber surface with active materials, forming the core of the battery with a separator, and injecting electrolytes or developing solid / quasi-solid electrolytes. Although carbon fiber itself can be used as a negative electrode, its direct participation in the reaction as an active material leads to a decrease in its mechanical properties, and the stability of the battery under complex loads cannot be effectively guaranteed. Furthermore, existing solutions do not fundamentally change the packaging arrangement of structural batteries; they mostly encapsulate the core of the battery with PP film or aluminum-plastic film, then add an outer layer of carbon fiber cloth to the upper and lower surfaces of the cell, and finally assemble the outer fibers with the core battery using methods such as vacuum-assisted dip coating (VARI) or prepreg molding. In this method, the physical continuity between the core battery region and the outer structural layer is poor, resulting in a significant decrease in the overall mechanical performance of the structural battery.

[0004] To address the aforementioned issues, relevant literature proposes a method to extend the carbon fiber negative electrode from the battery core region, allowing it to be co-cured and formed with the supporting carbon fiber cloth outside the core region. This ensures the integrity of the carbon fiber in the load-bearing direction and improves its mechanical properties. The core process involves sealing localized areas of the carbon fiber with resin and combining this with a composite film to create a sealed environment for the battery core region. However, this approach still has key technical limitations:

[0005] (1) Only the positive electrode is extended, while the negative electrode still uses traditional lithium sheets, resulting in a significant thickness difference between the core battery area and the support area, discontinuous interface structure, and limited improvement of mechanical performance; (2) There are natural differences in the lithium storage potential, capacity and reaction kinetics of the positive and negative electrode carbon fibers. The existing modification process cannot achieve the matching of the two electrochemical parameters, which is prone to charge-discharge imbalance; the sealing structure of the existing modification process (resin local encapsulation + composite film) cannot be adapted to the bidirectional extension boundary, which is prone to electrolyte leakage; (3) The difference in the braiding structure and resin wettability of the positive and negative electrode carbon fibers leads to uneven thickness and fiber misalignment during the extension process, which destroys the structural continuity between the battery area and the support area and reduces mechanical performance.

[0006] In addition, actual engineering requires high voltage or high current output, but the integrated fabrication of series / parallel structural batteries faces the following challenges: (1) Structural batteries need to simultaneously undertake electrochemical energy storage and structural support functions. When connected in series / parallel, additional structures such as electrode connection and insulation isolation are required. However, these components will disrupt the mechanical continuity of the structural battery (such as increasing thickness difference and introducing stress concentration points), resulting in a decrease in overall load-bearing performance, which violates the core requirement of integrated structural energy storage. (2) Series / parallel connection has extremely high requirements for the consistency of voltage, capacity and internal resistance of battery cells. However, the fabrication process of structural batteries (such as the extension of carbon fiber electrodes and resin encapsulation) can easily lead to differences in the electrochemical performance of different cells. Direct series / parallel connection will result in the barrel effect, and the weakest cell may limit the overall output, or even cause problems such as overcharging / over-discharging and life decay. (3) The existing fabrication of structural batteries focuses on the integration of single cells and support areas. However, series / parallel connection needs to achieve electrode connection, electrolyte interconnection and sealing isolation of multiple battery cells while maintaining structural continuity. Currently, there is a lack of suitable process solutions.

[0007] Therefore, in order to further improve the overall mechanical performance of carbon fiber structure batteries and meet the requirements for output voltage and current under complex actual working conditions, it is urgent to conduct in-depth research on the integrated molding process and series-parallel design methods of carbon fiber structure batteries. Summary of the Invention

[0008] Existing technologies suffer from poor mechanical continuity, inadequate sealing and leakage prevention, and inability to meet the demands of high voltage or high current output. This invention proposes an integrated molding and series-parallel fabrication method for composite material structure batteries. Through bidirectional extension design of positive and negative electrodes, dense sealing process of transition zone, and integrated series-parallel molding scheme, a deep integration of energy storage function and mechanical load-bearing performance is achieved.

[0009] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0010] A method for integral molding and series-parallel connection fabrication of composite material structure batteries, the method comprising the following steps:

[0011] S1. Analyze the bidirectional extended structural characteristic parameters of the composite material structure battery to be prepared, and extract the core structural parameters, including the length and width of the positive and negative electrode active regions, the width of the strip transition region from the carbon fiber positive and negative electrodes to the support region, the weaving density and single-layer thickness of the carbon fiber fabric, and the overall structural requirements for the mechanical load-bearing strength and sealing and impermeability of the transition region. Based on the structural parameters obtained from the analysis, and combined with the interfacial bonding characteristics between carbon fiber and resin and the electrolyte barrier requirements, calibrate the basic process parameters within the preset process parameter range.

[0012] S2, the carbon fiber fabric surface is degummed, cleaned and dried to obtain a clean carbon fiber current collector.

[0013] S3, design the active material ratio for the positive and negative electrodes of the battery respectively, mix the active material, conductive agent and binder in proportion to prepare the electrode active material slurry; coat the electrode active material slurry in the middle local area of ​​the single-layer carbon fiber fabric to form the battery active area, and retain the remaining area of ​​the carbon fiber fabric as the mechanical bearing area, thus performing functional zoning of the carbon fiber fabric.

[0014] S4. Resin is applied to the strip transition area at the junction of the battery active area and the mechanical bearing area. After stacking carbon fiber fabric in the order of positive electrode, separator and negative electrode, a special concave and convex clamp is used to perform local limiting and pre-compression treatment on the strip transition area. The resin matrix of the pre-compressed strip transition area is hot-pressed and cured to form a dense, sealed hard strip that physically isolates the battery active area from the mechanical bearing area.

[0015] S5 uses a sealing film to encapsulate the core area of ​​the battery in an ultra-clean glove box, injects electrolyte and leads out the tabs, and forms a single cell structure after sealing and activation treatment; several single cells are stacked in the thickness direction, and a carbon fiber transition layer is inserted between adjacent single cells. According to the voltage or capacity requirements, the tabs of each single cell are connected in series or parallel to construct the battery core module.

[0016] The S6 features a carbon fiber cloth laid on the outer layer of the core battery module, and vacuum-assisted resin injection technology is used for overall impregnation and curing to obtain an integrated composite material structure battery.

[0017] Step S1 further includes:

[0018] S11. Based on the actual application scenarios of composite material structure batteries, the mechanical load-bearing requirements, energy storage output requirements, and structural size limitations are determined. Based on engineering requirements, the basic model of carbon fiber fabric is selected, and the weaving density and single-layer thickness of the carbon fiber fabric are determined. A three-dimensional structural simulation model of the composite material structure battery is constructed based on the overall layout of the bidirectional extension of the carbon fiber positive and negative electrodes. Based on energy storage output requirements, combined with the surface loading of active material and the overall structural size limitations, the length and width ranges of the positive and negative electrode active regions are calculated through simulation. Based on mechanical simulation, combined with mechanical load-bearing requirements and sealing and seepage prevention requirements, the width range of the strip transition region from the carbon fiber positive and negative electrodes to the load-bearing area is determined. All extracted structural parameters are verified by multi-objective coupled simulation. Based on engineering requirements, the value ranges of conflicting parameters are corrected, and finally, a list of bidirectional extension structure characteristic parameters is formed.

[0019] S12, based on the mechanical load requirements and the range of width values ​​for the strip transition area determined in step S11, the minimum allowable interfacial shear strength and minimum allowable tensile strength of the strip transition area are determined through mechanical simulation, serving as the mechanical load strength indicators of the transition area; based on the electrolyte usage type and battery cycle life requirements, combined with the structural parameters of the strip transition area, the minimum allowable electrolyte immersion time without leakage and the maximum allowable resin layer porosity of the strip transition area are determined, serving as the sealing and seepage prevention indicators of the transition area;

[0020] S13. Based on the extracted list of bidirectional elongation structure characteristic parameters, combined with the interfacial bonding characteristics of carbon fiber and resin and the electrolyte barrier requirements, within the preset process parameter range, and with the mechanical load-bearing strength index and sealing and impermeability index of the transition zone as constraints, the basic process parameters suitable for the bidirectional elongation structure of carbon fiber positive and negative electrodes are calibrated through material characteristic testing and process parameter correlation analysis. The correlation between all calibrated basic process parameters and the performance index of the transition zone is greater than the preset correlation threshold.

[0021] S14. Take a number of carbon fiber fabrics and resins, prepare small samples of the strip transition zone according to the calibrated basic process parameters, and test the performance of the small samples. If the test results do not meet the performance index of the transition zone, the process parameters are finely adjusted in a gradient within the preset process parameter range and the small samples are prepared and tested again until the performance of the small samples meets the requirements. Finally, the suitable basic process parameters are determined.

[0022] Step S2 further includes:

[0023] The sizing agent and impregnating agent on the surface of the continuous carbon fiber fabric were removed by pyrolysis using a muffle furnace. After pyrolysis, the fiber fabric was immersed in acetone solvent for ultrasonic cleaning to thoroughly remove residual carbon ash. Then it was placed in a vacuum oven to dry, resulting in a carbon fiber current collector with a clean surface and good wettability.

[0024] Step S3 further includes:

[0025] The active material ratios were designed for the positive and negative electrodes of the battery, respectively. Specifically, 3% to 5% polyvinylidene fluoride binder was dissolved in N-methylpyrrolidone solvent, premixed active powder was added, and the mixture was thoroughly mixed under vacuum using a planetary magnetic stirrer to prepare an electrode active material slurry.

[0026] The carbon fiber cloth is cut according to the design dimensions. A protective film is used to shield the mechanical load area. Electrode active material slurry is applied to the central battery active area using a precision doctor blade or air gun. After coating, the fabric is dried in a vacuum environment to completely remove the solvent. The active material loading is calculated by weighing the mass difference before and after coating, and it is ensured that the positive electrode active area is smaller than the negative electrode.

[0027] Step S4 further includes:

[0028] Epolam5015 epoxy resin and hardener were mixed at a preset mass ratio, and after being vacuumed and allowed to stand, the viscosity was adjusted to the optimal viscosity for wetting carbon fiber fabrics to obtain a high-performance resin.

[0029] The active area of ​​the battery is completely covered by a protective film, exposing only the strip transition area at the junction of the active area and the mechanical bearing area. The high-performance resin is evenly applied to this strip transition area. Carbon fiber fabrics that have been functionally partitioned are taken and stacked in the order of positive electrode carbon fiber fabric, separator, and negative electrode carbon fiber fabric. During the stacking process, high-performance resin is applied to the strip transition area of ​​each layer to ensure that the resin covers the transition area completely without any omissions.

[0030] Customized concave-convex mold fixtures are made according to the structural parameters of composite material structure batteries. The stacked carbon fiber fabric assembly is placed into the concave-convex mold fixtures, and the protrusions of the fixtures are aligned with the strip transition area. Static pressure is first applied to remove interlayer air bubbles, and then the fixtures are used to maintain a constant pre-pressure to perform local limiting and pre-compression treatment on the strip transition area.

[0031] The carbon fiber fabric assembly with concave and convex mold clamps is placed in a hot press molding machine, a preset constant pressure is applied, and high-temperature curing is carried out at the specified curing temperature and holding time. This allows the resin in the strip transition area to fully impregnate the carbon fiber and undergo a cross-linking reaction, forming a dense, sealed hard band, thus achieving physical isolation and functional decoupling between the battery active area and the mechanical load-bearing area.

[0032] Step S5 further includes:

[0033] Inside an ultra-clean glove box where both water and oxygen content are below 1 ppm, metal tabs are led out from the dense sealing strip of the strip transition area using conductive silver adhesive bonding or ultrasonic welding. A hot melt adhesive auxiliary sealing layer is arranged at the edge of the strip transition area, covering a polyamide / polyethylene composite sealing film. A hot press sealing machine is used to seal the three sides of the battery core area, and a quantitative electrolyte is injected by a pipette to complete the final sealing. The sealed individual battery cells are subjected to charge-discharge cycle testing, and then returned to the ultra-clean glove box for secondary venting and resealing to ensure that there are no air bubbles or electrolyte leakage in the battery core area. The boundary of the battery core area is defined by the sealing rigid strip of the strip transition area.

[0034] Based on the target voltage or capacity requirements, several individual cells are neatly stacked along the thickness direction, and a pre-treated carbon fiber transition layer is inserted between two adjacent layers of individual cells. The carbon fiber transition layer is made of the same material as the carbon fiber fabric in the mechanical bearing area of ​​the individual cells to enhance the interlayer shear strength of the module. The series structure achieves voltage superposition by bonding the positive and negative tabs of adjacent individual cells to each other, while the parallel structure achieves capacity expansion by welding the same polarity tabs of all individual cells together. Finally, the leads are connected to the main positive and negative terminals to form a flexible or rigid battery core module.

[0035] Step S6 further includes:

[0036] Two layers of carbon fiber reinforced fabric are added as a skin to the outer layer of the battery core module. The carbon fiber reinforced fabric is the same material as the carbon fiber fabric selected in step S1, and the laying direction is aligned with the fiber direction of the carbon fiber transition layer inside the battery core module.

[0037] The battery core module after the skin is laid is placed in a single-sided hard mold or vacuum bag system. A release cloth and a flow guide net are laid between the module and the mold or vacuum bag in sequence. At the same time, a resin injection port and a vacuum extraction port are set at the preset position.

[0038] Vacuum-assisted resin injection technology is adopted. A stable negative pressure environment is formed in the system by drawing a vacuum through the vacuum port. The negative pressure is used to introduce low-viscosity structural resin from the injection port, driving the resin to completely wet the outer carbon fiber reinforced cloth, the gap of the battery core module and the carbon fiber area that is not fully wetted.

[0039] After the resin is injected, it is kept in a vacuum environment and allowed to cure at room temperature, so that the resin can fully cross-link and form a strong bond with the carbon fiber, ultimately forming an integrated composite material structure battery with excellent mechanical load-bearing capacity and efficient energy storage function.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] First, the integrated molding and series-parallel fabrication method for composite material structure batteries of the present invention achieves integrated fabrication of the battery active area and resin molding by analyzing pre-structure parameters and accurately calibrating process parameters, combined with the design of specific active slurry ratios for positive and negative electrodes. Relying on the functional zoning design of a single-layer continuous carbon fiber fabric, and with the precise positioning and molding control of a special concave-convex clamp, the carbon fiber current collector achieves bidirectional continuous extension between the battery area and the support area, effectively avoiding physical discontinuities within the structure and significantly reducing the impact of traditional battery integration methods on the overall mechanical properties of the composite material.

[0042] Secondly, the integrated molding and series-parallel fabrication method of the composite material structure battery of the present invention, combined with the local pressure sealing process of the transition region, forms a dense resin matrix barrier band inside the fiber layer. Through the four-fold sealing design of hot-pressing and curing the dense resin barrier band in the transition region, hot melt adhesive auxiliary sealing at the edge of the transition region, polyamide / polyethylene composite sealing film encapsulation, and secondary venting and resealing, the problem of electrolyte leakage is fundamentally solved. On this basis, with the flexible series-parallel molding design, the output specifications can be flexibly adjusted according to the actual complex working conditions and the voltage and current requirements. Through standardized preparation of single cells and module screening, electrochemical consistency is ensured.

[0043] Third, the integrated molding and series-parallel fabrication method of composite material structure batteries of the present invention ensures the rationality and adaptability of process parameters through standardized parameter calibration throughout the entire process, dedicated fixture positioning and multi-stage verification, taking into account both product performance stability and the needs of industrial mass production. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of different areas of a single-layer fiber cloth;

[0045] Figure 2 Concave and convex clamps for shaping transition areas;

[0046] Figure 3 This is a schematic diagram of the battery area sealing.

[0047] Figure 4 This is a schematic diagram of a series and parallel connection of a battery structure.

[0048] Figure 5 This is a schematic diagram of the structure forming based on the VARI method. Detailed Implementation

[0049] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0050] This invention discloses a method for the integrated molding and series-parallel fabrication of composite material structure batteries, the method comprising the following steps:

[0051] S1 involves analyzing the bidirectional extension structural characteristic parameters of the composite material battery to be prepared, extracting core structural parameters including the length and width of the positive and negative electrode active regions, the width of the strip transition region from the carbon fiber positive and negative electrodes to the support region, the weaving density and single-layer thickness of the carbon fiber fabric, and the overall structural requirements for the mechanical load-bearing strength and sealing impermeability of the transition region. Based on the analyzed structural parameters, combined with the interfacial bonding characteristics between carbon fiber and resin and the electrolyte barrier requirements, the basic process parameters are calibrated within the preset process parameter range. Step S1 specifically includes the following steps:

[0052] S11, Structural Parameter Determination: Based on the actual application scenarios of the composite material structure battery, determine the mechanical load-bearing requirements, energy storage output requirements, and structural size limitations; based on engineering requirements, select the basic model of carbon fiber fabric and determine its basic parameters such as weaving density and single-layer thickness; then, combined with the overall layout of the bidirectional extension of carbon fiber positive and negative electrodes, construct a three-dimensional structural simulation model of the composite material structure battery using software such as SolidWorks or ABAQUS; based on energy storage output requirements, combined with the surface loading of active material and overall structural size limitations, calculate the length and width range of the positive and negative electrode active regions through simulation; based on mechanical simulation, combined with mechanical load-bearing requirements and sealing and seepage prevention requirements, determine the width range of the strip transition region from the carbon fiber positive and negative electrodes to the load-bearing area; perform multi-objective coupled simulation verification on all extracted structural parameters. If there are parameter conflicts (such as the active region area being too large, resulting in insufficient transition region width), correct the value range of conflicting parameters based on engineering requirements, and finally form a complete list of bidirectional extension structural characteristic parameters.

[0053] S12, Performance indicators of the transition zone are determined: Based on the mechanical load requirements and the range of width values ​​of the strip transition zone determined in step S11, the minimum allowable interfacial shear strength and minimum allowable tensile strength of the strip transition zone are determined through mechanical simulation, which serve as the mechanical load strength indicators of the transition zone; Based on the electrolyte usage type and battery cycle life requirements, combined with the structural parameters of the strip transition zone, the minimum allowable electrolyte immersion time without leakage and the maximum allowable resin layer porosity of the strip transition zone are determined, which serve as the sealing and seepage prevention indicators of the transition zone.

[0054] S13, Determination of basic process parameters: Based on the extracted list of bidirectional elongated structural characteristic parameters, combined with the interfacial bonding characteristics of carbon fiber and resin and the electrolyte barrier requirements, within the preset process parameter range, and constrained by meeting the mechanical load-bearing strength index and sealing and impermeability index of the transition zone, the basic process parameters suitable for the bidirectional elongated structure of carbon fiber positive and negative electrodes are calibrated through material characteristic testing and process parameter correlation analysis. These parameters include resin coating thickness, pre-compression pressure, hot-pressing curing temperature, etc. The correlation between all calibrated basic process parameters and the performance index of the transition zone is greater than the preset correlation threshold (e.g., 90%), ensuring that the process parameters effectively support the performance index.

[0055] S14. Take a number of selected carbon fiber fabrics and resins, and prepare small samples of the strip transition zone according to the calibrated basic process parameters. Use a universal testing machine to test the interfacial shear strength and tensile strength of the prepared small samples, use a porosity meter to test the porosity of the resin layer, and use an electrolyte immersion test to test the impermeability. If the test results do not meet the performance indicators of the transition zone, the process parameters are finely adjusted in a gradient within the preset process parameter range, and small samples are prepared again for performance testing. Repeat the optimization until the performance of the small samples meets the requirements, and finally determine the suitable basic process parameters to ensure that the performance of the products prepared on a large scale meets the standards.

[0056] S2, the carbon fiber fabric surface is subjected to degumming, cleaning, and drying treatment to obtain a clean carbon fiber current collector. In this embodiment, a muffle furnace is used to pyrolyze and remove the sizing agent and wetting agent from the surface of the continuous carbon fiber fabric. In this embodiment, the muffle furnace temperature is set to 450°C and the pyrolysis treatment time is 0.5 hours to fully remove the surface organic adhesive layer. After pyrolysis, the fiber fabric is immersed in acetone solvent for ultrasonic cleaning. The ultrasonic power is set to 300W and the cleaning time is 20 minutes to thoroughly remove residual carbon ash. After cleaning, the carbon fiber fabric is placed in a vacuum oven and dried at 80°C for 12 hours to obtain a carbon fiber current collector with a clean surface and good wettability.

[0057] S3. The active material ratios for the positive and negative electrodes of the battery are designed separately. The active material, conductive agent (such as carbon black or carbon nanotubes), and binder are mixed in proportion to prepare an electrode active material slurry. This slurry is then coated onto a localized area in the middle of a single-layer carbon fiber fabric to form the battery active zone. The remaining areas of the carbon fiber fabric are retained as mechanical load-bearing areas, thus functionally dividing the carbon fiber fabric. In this example, the specific process is as follows: 3%~5% by mass of polyvinylidene fluoride (PVDF) binder is dissolved in N-methylpyrrolidone (NMP) solvent, and premixed active powder is added. The mixture is thoroughly mixed under vacuum using a planetary magnetic stirrer to prepare an electrode slurry with moderate viscosity and uniform composition. The carbon fiber fabric is then cut to the design dimensions determined in step S1. A protective film (such as a high-temperature resistant polytetrafluoroethylene protective film) is used to shield the non-active areas (mechanical load-bearing areas), exposing only the central battery active zone. The slurry is then applied to the central battery active zone using a precision doctor blade or air gun. After coating, the fabric is dried in a vacuum environment at 80°C for 12 hours to completely remove the solvent. The active material loading is accurately calculated by weighing the mass difference before and after coating, ensuring that the positive electrode active area is slightly smaller than the negative electrode to prevent lithium dendrite growth and optimize energy density. (See attached image) Figure 1 As shown.

[0058] S4. Apply resin to the strip transition area at the junction of the battery active area and the mechanical bearing area. Stack carbon fiber fabric in the order of positive electrode, separator and negative electrode. Use a special concave and convex clamp to perform local limiting and pre-compression treatment on the strip transition area. Hot press and cure the resin matrix of the pre-compressed strip transition area to form a dense, sealed hard strip that physically isolates the battery active area from the mechanical bearing area. For example, Epolam5015 epoxy resin and a hardener are mixed at a preset mass ratio, vacuum-treated, and allowed to stand. The viscosity is adjusted to the optimal viscosity for wetting carbon fiber fabric to obtain a high-performance resin. A protective film is then used to completely cover the battery active area, exposing only the strip transition area at the junction of the battery active area and the mechanical bearing area. High-performance resin is then evenly applied to this strip transition area. Positive and negative electrode carbon fiber fabrics, each with its functional partitioned structure, are stacked sequentially in the order of positive electrode carbon fiber fabric, separator, and negative electrode carbon fiber fabric. During stacking, high-performance resin is applied layer by layer to the strip transition area of ​​each layer to ensure complete resin coverage. A concave-convex mold fixture is customized according to the structural parameters determined in step S1. The stacked carbon fiber fabric assembly is placed into the concave-convex mold fixture, aligning the protrusions of the fixture with the strip transition area, as shown in the attached figure. Figure 2As shown; first, static pressure is applied to remove interlayer air bubbles, then a constant pre-pressure is maintained for 1-2 hours using a fixture to perform local limiting and pre-compression treatment on the strip transition area; finally, the carbon fiber fabric assembly with concave and convex mold fixtures is placed in a hot press molding machine, and a preset constant pressure (such as 0.1MPa-0.5MPa) is applied, while high-temperature curing is performed according to the specified curing temperature (80°C) and holding time (4 hours), so that the resin in the strip transition area fully impregnates the carbon fiber and undergoes a cross-linking reaction to form a dense, sealed hard band, realizing the physical isolation and functional decoupling between the battery active area and the mechanical load-bearing area.

[0059] S5 involves encapsulating the core area of ​​the battery within a cleanroom glove box using a sealing film, injecting electrolyte, and leading out the tabs. After sealing and activation, a single-cell battery structure is formed. Several single cells are stacked along their thickness, with carbon fiber transition layers inserted between adjacent cells. The tabs of each cell are connected in series or parallel according to voltage or capacity requirements to construct the battery core module. Specifically, within a cleanroom glove box where the water and oxygen content are both below 1 ppm, conductive silver adhesive or ultrasonic welding is used to lead out the metal tabs (aluminum / nickel) from the dense sealing strip of the strip transition area. A hot-melt adhesive auxiliary sealing layer is arranged at the edge of the strip transition area, covered with a PA / PE (polyamide / polyethylene) composite sealing film, as shown in the attached image. Figure 3 As shown, a hot-press sealing machine is used to seal the three sides of the core area of ​​the battery. A quantitative amount of electrolyte is injected through a pipette to complete the final sealing. The sealed individual cells are subjected to charge-discharge cycle tests, and then returned to the ultra-clean glove box for secondary venting and resealing to ensure that there are no air bubbles or electrolyte leakage in the core area of ​​the battery. The boundary of the core area of ​​the battery is defined by a rigid sealing strip in a strip transition area.

[0060] Based on target voltage or capacity requirements, several individual cells are neatly stacked along the thickness direction, with a pre-treated carbon fiber transition layer inserted between adjacent layers. The carbon fiber transition layer is made of the same material as the carbon fiber fabric in the mechanical load-bearing area of ​​the individual cells to enhance the interlayer shear strength of the module. The series structure achieves voltage superposition by alternately bonding the positive and negative tabs of adjacent individual cells, as shown in the attached diagram. Figure 4 As shown in (a), the parallel structure expands capacity by unifying and welding the same polarity tabs of all individual cells, and finally connects the leads to the main positive and negative terminals to form a flexible or rigid battery core module, as shown in the attached figure. Figure 4 As shown in (b) in the appendix; Figure 4 (c) is a top view of the series / parallel structure.

[0061] S6. A carbon fiber cloth is laid entirely on the outer layer of the battery core module. Vacuum-Assisted Resin Injection Technology (VARI) is used for overall impregnation and curing, ultimately resulting in an integrated composite material structure battery. Specifically, two layers of carbon fiber reinforcing cloth are added as a skin to the outer layer of the battery core module. The carbon fiber reinforcing cloth is of the same material as the carbon fiber fabric selected in step S1, and its laying direction is aligned with the fiber direction of the carbon fiber transition layer inside the battery core module to ensure overall mechanical continuity. The battery core module with the skin laid is placed in a single-sided hard mold or vacuum bag system. A release cloth and a flow guide net are sequentially laid between the module and the mold or vacuum bag. Resin injection ports and vacuum extraction ports are set at preset positions, as shown in the attached diagram. Figure 5 As shown, vacuum-assisted resin injection technology is employed. A stable negative pressure environment is created within the system by drawing a vacuum through a vacuum extraction port. This negative pressure is used to introduce low-viscosity structural resin (such as Epolam5015) through the injection port, driving the resin to completely impregnate the outer carbon fiber reinforcement fabric, the gaps between the battery core modules, and the areas of carbon fiber that are not fully impregnated, ensuring no dry spots or bubbles. After resin injection, the system is kept in a vacuum environment and allowed to cure at room temperature for 24 hours, allowing the resin to fully cross-link and form a strong bond with the carbon fiber, ultimately forming an integrated composite material structure battery that combines excellent mechanical load-bearing capacity with high-efficiency energy storage function.

[0062] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0063] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for integrated molding and series-parallel fabrication of composite material structure batteries, characterized in that, The method includes the following steps: S1. Analyze the bidirectional extended structural characteristic parameters of the composite material structure battery to be prepared, and extract the core structural parameters, including the length and width of the positive and negative electrode active regions, the width of the strip transition region from the carbon fiber positive and negative electrodes to the support region, the weaving density and single-layer thickness of the carbon fiber fabric, and the overall structural requirements for the mechanical load-bearing strength and sealing and impermeability of the transition region. Based on the structural parameters obtained from the analysis, and combined with the interfacial bonding characteristics between carbon fiber and resin and the electrolyte barrier requirements, calibrate the basic process parameters within the preset process parameter range. S2, the carbon fiber fabric surface is degummed, cleaned and dried to obtain a clean carbon fiber current collector. S3, design the active material ratio for the positive and negative electrodes of the battery respectively, mix the active material, conductive agent and binder in proportion to prepare the electrode active material slurry; coat the electrode active material slurry in the middle local area of ​​the single-layer carbon fiber fabric to form the battery active area, and retain the remaining area of ​​the carbon fiber fabric as the mechanical bearing area, thus performing functional zoning of the carbon fiber fabric. S4. Resin is applied to the strip transition area at the junction of the battery active area and the mechanical bearing area. After stacking carbon fiber fabric in the order of positive electrode, separator and negative electrode, a special concave and convex clamp is used to perform local limiting and pre-compression treatment on the strip transition area. The resin matrix of the pre-compressed strip transition area is hot-pressed and cured to form a dense, sealed hard strip that physically isolates the battery active area from the mechanical bearing area. S5 uses a sealing film to encapsulate the core area of ​​the battery in an ultra-clean glove box, injects electrolyte and leads out the tabs, and forms a single cell structure after sealing and activation treatment; several single cells are stacked in the thickness direction, and a carbon fiber transition layer is inserted between adjacent single cells. According to the voltage or capacity requirements, the tabs of each single cell are connected in series or parallel to construct the battery core module. The S6 features a carbon fiber cloth laid on the outer layer of the core battery module, and vacuum-assisted resin injection technology is used for overall impregnation and curing to obtain an integrated composite material structure battery.

2. The method for integrated molding and series-parallel fabrication of composite material structure batteries according to claim 1, characterized in that, Step S1 further includes: S11. Based on the actual application scenarios of composite material structure batteries, the mechanical load-bearing requirements, energy storage output requirements, and structural size limitations are determined. Based on engineering requirements, the basic model of carbon fiber fabric is selected, and the weaving density and single-layer thickness of the carbon fiber fabric are determined. A three-dimensional structural simulation model of the composite material structure battery is constructed based on the overall layout of the bidirectional extension of the carbon fiber positive and negative electrodes. Based on energy storage output requirements, combined with the surface loading of active material and the overall structural size limitations, the length and width ranges of the positive and negative electrode active regions are calculated through simulation. Based on mechanical simulation, combined with mechanical load-bearing requirements and sealing and seepage prevention requirements, the width range of the strip transition region from the carbon fiber positive and negative electrodes to the load-bearing area is determined. All extracted structural parameters are verified by multi-objective coupled simulation. Based on engineering requirements, the value ranges of conflicting parameters are corrected, and finally, a list of bidirectional extension structure characteristic parameters is formed. S12, based on the mechanical load requirements and the range of width values ​​for the strip transition area determined in step S11, the minimum allowable interfacial shear strength and minimum allowable tensile strength of the strip transition area are determined through mechanical simulation, serving as the mechanical load strength indicators of the transition area; based on the electrolyte usage type and battery cycle life requirements, combined with the structural parameters of the strip transition area, the minimum allowable electrolyte immersion time without leakage and the maximum allowable resin layer porosity of the strip transition area are determined, serving as the sealing and seepage prevention indicators of the transition area; S13. Based on the extracted list of bidirectional elongation structure characteristic parameters, combined with the interfacial bonding characteristics of carbon fiber and resin and the electrolyte barrier requirements, within the preset process parameter range, and with the mechanical load-bearing strength index and sealing and impermeability index of the transition zone as constraints, the basic process parameters suitable for the bidirectional elongation structure of carbon fiber positive and negative electrodes are calibrated through material characteristic testing and process parameter correlation analysis. The correlation between all calibrated basic process parameters and the performance index of the transition zone is greater than the preset correlation threshold. S14. Take a number of carbon fiber fabrics and resins, prepare small samples of the strip transition zone according to the calibrated basic process parameters, and test the performance of the small samples. If the test results do not meet the performance index of the transition zone, the process parameters are finely adjusted in a gradient within the preset process parameter range and the small samples are prepared and tested again until the performance of the small samples meets the requirements. Finally, the suitable basic process parameters are determined.

3. The method for integrated molding and series-parallel fabrication of composite material structure batteries according to claim 1, characterized in that, Step S2 further includes: The sizing agent and impregnating agent on the surface of the continuous carbon fiber fabric were removed by pyrolysis using a muffle furnace. After pyrolysis, the fiber fabric was immersed in acetone solvent for ultrasonic cleaning to thoroughly remove residual carbon ash. Then it was placed in a vacuum oven to dry, resulting in a carbon fiber current collector with a clean surface and good wettability.

4. The method for integrated molding and series-parallel fabrication of composite material structure batteries according to claim 1, characterized in that, Step S3 further includes: The active material ratios were designed for the positive and negative electrodes of the battery, respectively. Specifically, 3% to 5% polyvinylidene fluoride binder was dissolved in N-methylpyrrolidone solvent, premixed active powder was added, and the mixture was thoroughly mixed under vacuum using a planetary magnetic stirrer to prepare an electrode active material slurry. The carbon fiber cloth is cut according to the design dimensions. A protective film is used to shield the mechanical load area. Electrode active material slurry is applied to the central battery active area using a precision doctor blade or air gun. After coating, the fabric is dried in a vacuum environment to completely remove the solvent. The active material loading is calculated by weighing the mass difference before and after coating, and it is ensured that the positive electrode active area is smaller than the negative electrode.

5. The method for integrated molding and series-parallel fabrication of composite material structure batteries according to claim 1, characterized in that, Step S4 further includes: Epolam5015 epoxy resin and hardener were mixed at a preset mass ratio, and after being vacuumed and allowed to stand, the viscosity was adjusted to the optimal viscosity for wetting carbon fiber fabrics to obtain a high-performance resin. The active area of ​​the battery is completely covered by a protective film, exposing only the strip transition area at the junction of the active area and the mechanical bearing area. The high-performance resin is evenly applied to this strip transition area. Carbon fiber fabrics that have been functionally partitioned are taken and stacked in the order of positive electrode carbon fiber fabric, separator, and negative electrode carbon fiber fabric. During the stacking process, high-performance resin is applied to the strip transition area of ​​each layer to ensure that the resin covers the transition area completely without any omissions. Customized concave-convex mold fixtures are made according to the structural parameters of composite material structure batteries. The stacked carbon fiber fabric assembly is placed into the concave-convex mold fixtures, and the protrusions of the fixtures are aligned with the strip transition area. Static pressure is first applied to remove interlayer air bubbles, and then the fixtures are used to maintain a constant pre-pressure to perform local limiting and pre-compression treatment on the strip transition area. The carbon fiber fabric assembly with concave and convex mold clamps is placed in a hot press molding machine, a preset constant pressure is applied, and high-temperature curing is carried out at the specified curing temperature and holding time. This allows the resin in the strip transition area to fully impregnate the carbon fiber and undergo a cross-linking reaction, forming a dense, sealed hard band, thus achieving physical isolation and functional decoupling between the battery active area and the mechanical load-bearing area.

6. The method for integrated molding and series-parallel fabrication of composite material structure batteries according to claim 1, characterized in that, Step S5 further includes: Inside an ultra-clean glove box where both water and oxygen content are below 1 ppm, metal tabs are led out from the dense sealing strip of the strip transition area using conductive silver adhesive bonding or ultrasonic welding. A hot melt adhesive auxiliary sealing layer is arranged at the edge of the strip transition area, covering a polyamide / polyethylene composite sealing film. A hot press sealing machine is used to seal the three sides of the battery core area, and a quantitative electrolyte is injected by a pipette to complete the final sealing. The sealed individual battery cells are subjected to charge-discharge cycle testing, and then returned to the ultra-clean glove box for secondary venting and resealing to ensure that there are no air bubbles or electrolyte leakage in the battery core area. The boundary of the battery core area is defined by the sealing rigid strip of the strip transition area. Based on the target voltage or capacity requirements, several individual cells are neatly stacked along the thickness direction, and a pre-treated carbon fiber transition layer is inserted between two adjacent layers of individual cells. The carbon fiber transition layer is made of the same material as the carbon fiber fabric in the mechanical bearing area of ​​the individual cells to enhance the interlayer shear strength of the module. The series structure achieves voltage superposition by bonding the positive and negative tabs of adjacent individual cells to each other, while the parallel structure achieves capacity expansion by welding the same polarity tabs of all individual cells together. Finally, the leads are connected to the main positive and negative terminals to form a flexible or rigid battery core module.

7. The method for integrated molding and series-parallel fabrication of composite material structure batteries according to claim 1, characterized in that, Step S6 further includes: Two layers of carbon fiber reinforced fabric are added as a skin to the outer layer of the battery core module. The carbon fiber reinforced fabric is the same material as the carbon fiber fabric selected in step S1, and the laying direction is aligned with the fiber direction of the carbon fiber transition layer inside the battery core module. The battery core module after the skin is laid is placed in a single-sided hard mold or vacuum bag system. A release cloth and a flow guide net are laid between the module and the mold or vacuum bag in sequence. At the same time, a resin injection port and a vacuum extraction port are set at the preset position. Vacuum-assisted resin injection technology is adopted. A stable negative pressure environment is formed in the system by drawing a vacuum through the vacuum port. The negative pressure is used to introduce low-viscosity structural resin from the injection port, driving the resin to completely wet the outer carbon fiber reinforced cloth, the gap of the battery core module and the carbon fiber area that is not fully wetted. After the resin is injected, it is kept in a vacuum environment and allowed to cure at room temperature, so that the resin can fully cross-link and form a strong bond with the carbon fiber, ultimately forming an integrated composite material structure battery with excellent mechanical load-bearing capacity and efficient energy storage function.

Images