Energy storage, circuit and load-bearing integrated circuit board composite structure and forming method thereof

Abstract

The present invention provides a circuit board composite structure integrating energy storage, circuit and load-bearing, and a molding method thereof. The molding steps include: stacking each layer in the order of a positive electrode carbon fiber reinforcement containing active material, a glass fiber separator, and a negative electrode carbon fiber, with one end of the carbon fiber bundle connected to the positive and negative electrode carbon fiber layers and the other end exposed to the laminated structure; mixing electrolyte and liquid resin in a certain proportion, and pouring them into the laminated structure to solidify and form a structural battery; laying glass fiber on the upper and lower surfaces of the structural battery respectively, and bending the exposed carbon fiber bundle to fit the outer surface of the glass fiber, and using liquid resin to infiltrate and solidify; finally, 3D printing the carbon fiber circuit, and post-curing to form a circuit board composite structure integrating energy storage, circuit and load-bearing; the circuit board composite structure prepared by the present invention greatly improves space and mass utilization, and is of great significance for equipment that is sensitive to volume and weight, such as aerospace carrier equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of multifunctional composite material manufacturing, and in particular to a circuit board composite structure integrating energy storage, circuit and load-bearing, and a forming method thereof. Background Art

[0002] The integration of material structure and function is the development direction of advanced intelligent equipment. It is crucial for equipment weight reduction, energy conservation and performance improvement. Faced with a series of challenges such as the current difficulty in extending the mileage of electric vehicles and the difficulty in designing zero-emission electric aircraft, how to design integrated multifunctional structural materials and bring out the full performance of the materials is an urgent problem that needs to be solved.

[0003] The circuit board is the core of intelligent equipment. Its main functional structure consists of a conductor layer and an insulation layer. The conductor layer is usually made of etched or printed copper foil, while the insulation layer uses glass fiber reinforced epoxy resin, which has weak mechanical properties. In addition, the circuit board generally does not contain energy storage components. Energy storage components are often connected to the circuit board through external circuits to provide power. Therefore, the circuit board is often protected as an internal component within the rigid outer structure, resulting in low performance utilization.

[0004] Chinese patent application number 201210129995.2 discloses a method for manufacturing a combined printed circuit board, a printed circuit board, and a method for manufacturing the same. While this method improves the rigidity of the combined printed circuit board, it still fails to address its energy storage issues. Chinese patent application number 201921304739.6 discloses a circuit board for a micro energy storage battery. Although a battery is fixed to one side of the top of the circuit board, the circuit board has a traditional assembly structure, relying on mechanical force to connect the battery to the circuit board. This makes the battery and circuit board difficult to bear force, and the functionality of each material is limited. Summary of the Invention

[0005] In response to the gaps in the existing technology, the present invention integrates circuit functions, mechanical properties and energy storage capabilities into the same material structure, greatly improving space and mass utilization. It is of great significance for volume and weight sensitive equipment such as aerospace vehicles. It also utilizes the integrated molding capabilities of energy-storage, highly conductive, and easily shaped carbon fibers and resins to achieve a composite circuit board structure that integrates energy storage, circuits, and load-bearing.

[0006] The object of the present invention is achieved through the following technical solutions:

[0007] In a first aspect, the present invention provides a composite structure of a circuit board integrating energy storage, circuit and load-bearing. The composite structure includes a first structural layer, a positive electrode, a first structural electrolyte, a diaphragm, a second structural electrolyte, a negative electrode, and a second structural layer arranged in sequence. The first and second structural layers are structural resins provided with an insulating layer. The carbon fiber circuit is arranged on the outer surface of any structural layer. The first carbon fiber bundle connects the positive electrode and one end of the carbon fiber circuit, and the second carbon fiber bundle connects the negative electrode and the other end of the carbon fiber circuit. The parts of the first and second carbon fiber bundles except the ends in contact with the carbon fiber circuit are embedded in the structural resin, or the structural resin and the structural electrolyte.

[0008] Preferably, the insulating layer and the diaphragm are glass fibers, and the carbon fiber circuit is a short-circuit circuit.

[0009] More preferably, the insulating layer and the diaphragm are high-strength S-glass fibers.

[0010] Preferably, the insulating layer in the first and second structural layers is located between the structural resins;

[0011] More preferably, in some embodiments, the insulating layer in the first and second structural layers is located on a side close to the outer surface of the structural resin.

[0012] In a second aspect, the present invention provides a method for forming a circuit board composite structure integrating energy storage, circuitry, and load-bearing, comprising the following steps:

[0013] S1. Coating a positive electrode slurry on the desized carbon fiber unidirectional tape and vacuum drying to obtain a positive electrode carbon fiber reinforcement containing an active material, i.e., the positive electrode; the desized carbon fiber unidirectional tape is used as a negative electrode carbon fiber, i.e., the negative electrode, the first carbon fiber bundle, and the second carbon fiber bundle;

[0014] S2. Lay the layers in the order of positive electrode, separator, and negative electrode; connect one end of the first carbon fiber bundle to the positive electrode and leave the other end exposed; connect one end of the second carbon fiber bundle to the negative electrode and leave the other end exposed (tighten the exposed ends of the first and second carbon fiber bundles with tape);

[0015] S3. Under anhydrous and oxygen-free conditions, mixing the liquid resin and the electrolyte in a certain proportion to form a structured electrolyte precursor;

[0016] S4, pouring a structural electrolyte precursor into the laminate structure described in S2, curing and forming the structural electrolyte, and obtaining a structural battery; during the pouring, the exposed ends of the first and second carbon fiber bundles are not soaked in the structural electrolyte precursor;

[0017] S5. Laying insulating layers on the upper and lower surfaces of the structural battery, respectively, and then bending the exposed ends of the first carbon fiber bundle and the second carbon fiber bundle to adhere to the outer surface of the insulating layer, and impregnating and curing the remaining portions except the exposed end points of the carbon fiber bundles with liquid resin to form a structural resin;

[0018] S6. (Uncover the tape at the end point of the carbon fiber bundle described in step S2, and start there, according to the designed circuit diagram) 3D print the carbon fiber circuit on the surface of the structural layer provided with the carbon fiber circuit, connect the exposed end points of the first carbon fiber bundle and the second carbon fiber bundle, and (curing and molding) obtain a circuit board composite structure integrating energy storage, circuit and load-bearing.

[0019] Preferably, in step S1, the positive electrode slurry is prepared by mixing conductive particles, a binder, and an active material, and dissolving the mixture in a solvent to form a positive electrode slurry; the conductive particles include at least one of carbon black particles and acetylene black, the binder includes at least one of polyvinylidene fluoride and sodium carboxymethyl cellulose, and the active material includes lithium iron phosphate, lithium manganate, lithium cobaltate, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM111), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523),LiNi 0.8 Co 0.1 Mn 0.1 At least one of O2 (NCM811).

[0020] Preferably, the mass ratio of the conductive particles, the binder, and the active material is in the range of 1:1:3 to 1:1:8.

[0021] Preferably, the solvent comprises N-methylpyrrolidone.

[0022] Preferably, in step S1, the desized carbon fiber unidirectional tape is a desized carbon fiber unidirectional tape calcined at a high temperature in air.

[0023] Preferably, the high-temperature calcination temperature is 300-500° C. and the time is 1-2 hours.

[0024] Preferably, in step S1, the drying temperature is 100-150°C.

[0025] Preferably, the woven structure of the positive electrode carbon fiber reinforcement containing active material, glass fiber and negative electrode carbon fiber includes one of unidirectional fabric, plain fabric, twill fabric, satin fabric or three-dimensional woven fabric; the woven structure of the carbon fiber bundle includes one of unidirectional fiber bundle or woven fiber bundle.

[0026] Preferably, in step S2, the tape includes one of polytetrafluoroethylene tape, polyethylene tape, polypropylene tape, and polyester tape. The lubricated non-stick tape is used to prevent liquid resin from infiltrating and affecting the contact conductivity at the carbon fiber endpoints.

[0027] Preferably, in step S3, the liquid resin includes one of epoxy resin, bismaleimide resin, polyimide resin, polyetheretherketone resin or phenolic resin, and the electrolyte includes at least one of LiPF6, LiTf, and LiTFSI electrolyte.

[0028] Preferably, in step S3, the mass ratio of the liquid resin to the electrolyte is 3:7-7:3.

[0029] Preferably, in step S5, during the liquid resin infiltration and curing process, except for the end points of the carbon fiber bundles connected to the structural battery, which are impregnated with resin and cured, the end points of other carbon fiber lines are not impregnated with resin and the fibers are exposed.

[0030] Preferably, the structural battery part of the circuit board composite structure with integrated energy storage, circuit and load-bearing can be repeatedly stacked in the order of positive electrode, diaphragm, and negative electrode as a cycle, and the capacity can be increased in parallel or the voltage can be increased in series; the thickness of the glass fiber (i.e., insulating layer) covering the upper and lower outer sides of the structural battery can be increased according to the required resistivity or dielectric constant to meet the insulation requirements.

[0031] In a third aspect, the present invention provides a method for using the composite structure, wherein the pins of the patch components are pressed to the open-circuit end points of the carbon fiber circuit with a certain pressure (forming a closed circuit), and are then impregnated with room-temperature curing epoxy resin for curing and fixing.

[0032] Preferably, the pressure is 0.06-0.1 MPa.

[0033] Based on traditional lightweight and high-strength carbon fibers, the present invention further considers the high lithium embedding capacity and high conductivity of its graphite structure to achieve energy storage and circuit functions. At the same time, it utilizes the bonding and packaging characteristics of high-mechanical performance resins and the ionic conductivity of the electrolyte to design a structural electrolyte, and performs integrated packaging and curing molding based on the resin, thereby realizing an integrated composite structure of energy storage, circuits and load-bearing, effectively improving the utilization efficiency of material performance. Compared with traditional assembled batteries and circuit boards, it not only reduces the volume and mass, but also realizes the mechanical bearing of the energy storage circuit board, and can serve as a load-bearing support structure while storing energy and transmitting signal power.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) The present invention integrates the structural battery and the circuit into an integrated form. The structural battery serves as a carrier with high mechanical properties and also as a high energy density energy storage element. The carbon fiber circuit can realize the conduction of current and electrical signals on the one hand, and can also bear loads on the other hand, so that the traditional circuit board is transformed from a centralized protection mode to a distributed load-bearing intelligent structural shell.

[0036] (2) The present invention fully utilizes the characteristics of carbon fiber, such as light weight, high modulus, high strength, high electrochemical capacity, low resistance, easy control of fiber shape, resin bonding, and phase change molding, and fully utilizes the various physical properties of the material to reduce volume and weight.

[0037] (3) The present invention covers the upper and lower surfaces of the structural battery with glass fibers, thereby encapsulating the battery to prevent the electrolyte from contacting water and oxygen, and also ensuring the insulation performance required by the circuit board insulation layer.

[0038] (4) Compared with traditional circuit boards, the present invention can form more complex geometries to meet the requirements of structural space design, including but not limited to arcs, variable cross-sections or bends. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0040] Figure 1 A schematic diagram of a circuit board composite structure integrating energy storage, circuits, and load-bearing;

[0041] Among them, 1-carbon fiber circuit; 2-first carbon fiber fiber bundle; 3-structural resin; 4-first structural electrolyte; 5-insulating layer; 6-positive electrode; 7-diaphragm; 8-negative electrode; 9-second carbon fiber fiber bundle; 10-second structural electrolyte; 11-second structural layer; 12-first structural layer. DETAILED DESCRIPTION

[0042] The present invention will be described in detail below with reference to specific embodiments and the accompanying drawings. The following examples will help those skilled in the art further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that those skilled in the art may make various changes and modifications without departing from the scope of the present invention. These modifications and improvements fall within the scope of protection of the present invention.

[0043] Example 1

[0044] The present embodiment provides a circuit board composite structure integrating energy storage, circuit and load-bearing, the composite structure comprising a first structural layer (12), a positive electrode (6), a first structural electrolyte (4), a diaphragm (7), a second structural electrolyte (10), a negative electrode (8), and a second structural layer (11) arranged in sequence, the first and second structural layers being structural resins (3) provided with an insulating layer (5) therein, a carbon fiber circuit (1) being arranged on the outer surface of any structural layer, a first carbon fiber bundle (2) connecting the positive electrode and one end of the carbon fiber circuit, a second carbon fiber bundle (9) connecting the negative electrode and the other end of the carbon fiber circuit, and portions of the first and second carbon fiber bundles except for the ends in contact with the carbon fiber circuit being embedded in the structural resin, or the structural resin and the structural electrolyte.

[0045] The specific molding steps are as follows:

[0046] T1, T700 carbon fiber unidirectional tape after desizing after calcination at 400℃ for 1.5h in air;

[0047] T2, conductive carbon black particles (Super P): polyvinylidene fluoride (PVDF): LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811) was mixed in a mass ratio of 1:1:8, dissolved in N-methylpyrrolidone (NMP), and stirred to form a positive electrode slurry;

[0048] T3, coating the positive electrode slurry described in step T2 on the T700 carbon fiber unidirectional tape after desizing described in step T1, drying at a high temperature (120° C.) in vacuum, and drying the NMP to obtain a positive electrode T700 carbon fiber reinforcement containing NCM811 active material (i.e., the positive electrode); the desizing T700 carbon fiber unidirectional tape is used as the negative electrode carbon fiber, i.e., the negative electrode, the first carbon fiber bundle, and the second carbon fiber bundle;

[0049] T4. Lay up the layers in the order of T700 positive electrode carbon fiber fabric containing NCM811 active material (i.e., positive electrode), high-strength S glass fiber separator (i.e., separator), and negative electrode T700 carbon fiber fabric (i.e., negative electrode), with one end of the carbon fiber bundle in close contact with the adjacent carbon fiber layer and the other end exposed in the laminated structure (i.e., one end of the first carbon fiber bundle is connected to the positive electrode and the other end is exposed; one end of the second carbon fiber bundle is connected to the negative electrode and the other end is exposed), and wrap the ends tightly with PTFE tape;

[0050] T5. In the absence of water and oxygen, a commercial room temperature curing structural epoxy resin (E-51) and a LiPF6 ion electrolyte were mixed in equal amounts to form a structural electrolyte precursor;

[0051] T6. Infusing the structural electrolyte precursor described in T5 into the laminate structure described in T4, curing and forming the structural electrolyte to obtain a structural battery. During the pouring process, the exposed portions of the T700 carbon fiber bundles (i.e., the first and second carbon fiber bundles) are prevented from being infiltrated by the structural electrolyte precursor.

[0052] T7. Cover the upper and lower surfaces of the cured structural battery described in T6 with high-strength S-glass fiber (i.e., insulating layer), bend the T700 carbon fiber bundle (exposed end) and adhere it to the outer surface of the glass fiber fabric (i.e., insulating layer), and use E-51 epoxy resin to impregnate and cure it again to form a structural resin;

[0053] T8, uncover the PTFE tape at the end point of the carbon fiber bundle described in T4, and start from there, according to the designed circuit diagram (such as Figure 1 (As shown) 3D printed T700 carbon fiber circuit, post-cured to form a circuit board composite structure that integrates energy storage, circuits, and load-bearing.

[0054] Effect test

[0055] Mechanical properties test: Tensile test refers to ASTM D3039 Standard test method for tensile properties of polymer matrix composites; flexural test refers to ASTM D790 Standard test method for flexural properties of unreinforced and reinforced plastics and electrical insulating materials.

[0056] Electrical performance test: Using a battery testing system, the obtained structural battery was charged and discharged at a single rate constant current to test the battery energy density; an electrochemical workstation was used to test the structural battery impedance, with an AC voltage amplitude of 0.01V and a frequency range of 0.01Hz-100kHz.

[0057] Circuit function test: Press the pins of two 1.5V small lamp beads to the open-circuit end points of the carbon fiber circuit of the circuit board composite structure prepared in Example 1 at an atmospheric pressure of 0.1 MPa to form a closed circuit, and then impregnate them with room temperature curing epoxy resin to cure and fix them to complete the circuit function test.

[0058] See Table 1 for specific data:

[0059] Table 1

[0060] Test performance Test data Tensile modulus 34.1GPa tensile strength 369.5MPa flexural modulus 29.3GPa Bending strength 191.3MPa Battery energy density 78.9Wh / kg Platform voltage 3.38V impedance 584Ω Circuit Function After the structural battery is fully charged, disconnect the external power supply and the small light bead will light up automatically.

[0061] Traditional commercially available EW220 glass fiber / 5284 epoxy resin circuit boards have a tensile modulus of 14.2 GPa and a tensile strength of 312.3 MPa, resulting in poor mechanical properties and requiring an external power supply. However, the circuit board composite structure, manufactured using the molding method of the present invention, integrates energy storage, circuitry, and load-bearing components. After the battery portion is fully charged, the small light beads can be automatically illuminated even when disconnected from the external power supply, and exhibits excellent electrical and mechanical properties.

[0062] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0063] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A method for forming a circuit board composite structure integrating energy storage, circuit and load-bearing, characterized in that: The following steps are involved: S1. Coating a positive electrode slurry on the desized carbon fiber unidirectional tape and vacuum drying to obtain a positive electrode carbon fiber reinforcement containing an active material, i.e., a positive electrode; the desized carbon fiber unidirectional tape is used as a negative electrode carbon fiber, i.e., a negative electrode; the desized carbon fiber unidirectional tape is also used as a first carbon fiber bundle and a second carbon fiber bundle; S2. Lay the layers in the order of positive electrode, separator, and negative electrode; connect one end of the first carbon fiber bundle to the positive electrode and expose the other end; connect one end of the second carbon fiber bundle to the negative electrode and expose the other end; S3. Under anhydrous and oxygen-free conditions, mixing the liquid resin and the electrolyte in a certain proportion to form a structured electrolyte precursor; S4, pouring a structural electrolyte precursor into the laminate structure described in S2, curing and forming the structural electrolyte, and obtaining a structural battery; during the pouring, the exposed ends of the first and second carbon fiber bundles are not soaked in the structural electrolyte precursor; S5. Laying insulating layers on the upper and lower surfaces of the structural battery, respectively, and then bending the exposed ends of the first carbon fiber bundle and the second carbon fiber bundle to adhere to the outer surface of the insulating layer, and impregnating and curing the remaining portions of the carbon fiber bundle except the exposed end points with liquid resin to form a structural resin, thereby forming a structural layer. S6. 3D print a carbon fiber circuit on the surface of the structural layer, connect the exposed end points of the first carbon fiber bundle and the second carbon fiber bundle, and produce a circuit board composite structure integrating energy storage, circuit and load-bearing.

2. The molding method according to claim 1, characterized in that In step S1, the positive electrode slurry is prepared by mixing conductive particles, a binder, and an active material, and dissolving them in a solvent to form a positive electrode slurry; the conductive particles include at least one of carbon black particles and acetylene black, the binder includes at least one of polyvinylidene fluoride and sodium carboxymethyl cellulose, and the active material includes lithium iron phosphate, lithium manganate, lithium cobalt oxide, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2、LiNi 0.5 Co 0.2 Mn 0.3 O2、LiNi 0.8 Co 0.1 Mn 0.1 At least one of O2.

3. The molding method according to claim 2, characterized in that The mass ratio of the conductive particles, the binder and the active material is in the range of 1:1:3 to 1:1:

8.

4. The molding method according to claim 2, characterized in that: The solvent includes N-methylpyrrolidone.

5. The molding method according to claim 1, characterized in that In step S3, the liquid resin includes one of epoxy resin, bismaleimide resin, polyimide resin, polyetheretherketone resin or phenolic resin, and the electrolyte includes at least one of LiPF6, LiTf, and LiTFSI electrolyte.

6. The molding method according to claim 1, characterized in that In step S3, the mass ratio of the liquid resin to the electrolyte is 3:7-7:

3.

7. A circuit board composite structure integrating energy storage, circuit and load-bearing prepared by the molding method according to any one of claims 1 to 6, characterized in that: The composite structure includes a first structural layer, a positive electrode, a first structural electrolyte, a diaphragm, a second structural electrolyte, a negative electrode, and a second structural layer arranged in sequence. The first and second structural layers are structural resins with an insulating layer provided therein. The carbon fiber circuit is arranged on the outer surface of any structural layer. The first carbon fiber bundle connects the positive electrode and one end of the carbon fiber circuit, and the second carbon fiber bundle connects the negative electrode and the other end of the carbon fiber circuit. The parts of the first and second carbon fiber bundles except for the ends in contact with the carbon fiber circuit are all embedded in the structural resin, or the structural resin and the structural electrolyte.

8. The composite structure according to claim 7, characterized in that The insulating layer and the diaphragm are made of glass fiber, and the carbon fiber circuit is a short-circuit circuit.

9. A method for using the composite structure according to claim 7, characterized in that: The pins of the surface-mount components are pressed to the disconnected ends of the carbon fiber circuit with a certain pressure, and then impregnated with epoxy resin that cures at room temperature to cure and fix them.

10. The method of use according to claim 9, characterized in that: The pressure is 0.06-0.1 MPa.

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