Lightweight flexible composite micro energy storage module

Abstract

The invention provides a lightweight flexible composite micro-energy storage module, which comprises a flexible substrate, a composite electrode layer, a solid electrolyte layer and a packaging layer, and is characterized in that the flexible substrate is made of a polyurethane-graphene composite material, the thickness of the flexible substrate is 50-200 [mu] m, and the surface of the flexible substrate is provided with a micro-crack structure; the composite electrode layer is formed by alternately stacking MXene / silicon carbon composite nanosheets and polypyrrole conductive polymers, wherein the mass ratio of MXene to silicon carbon is 3: 1 to 5: 1. According to the invention, through the mechanical interlocking design of the microcrack structure of the flexible substrate and the composite electrode layer, the interlayer binding force is significantly enhanced, and the structural integrity under dynamic bending is improved; the root-shaped ion transmission channel of the solid electrolyte layer and the vertical orientation transition layer realize electron-ion dual-channel cooperative transmission and reduce the interface impedance; the gradient hydrophobic structure of the packaging layer is matched with mechanics through chemical bonding, the sealing performance, the flexibility and the environmental tolerance are balanced, and the service life of the module is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of solid-state micro energy storage, and in particular to a lightweight flexible composite micro energy storage module. Background Art

[0002] Flexible energy storage devices are energy storage devices that can still function normally under deformation conditions such as bending, folding, and twisting within a certain range. They are mainly used in flexible electronic devices. The development of flexible energy storage devices is mainly due to the rise of flexible electronic devices, such as wearable sensors, implantable medical devices, and flexible displays. Traditional flexible energy storage devices have the following limitations:

[0003] 1. Interface problems: Mechanical stress can easily lead to delamination between the electrode, substrate, and electrolyte layer, reducing cycle life;

[0004] 2. Material defects: The volume expansion of silicon-based electrodes is serious, and the homogenized design of the encapsulation layer is difficult to achieve a balance between sealing and flexibility;

[0005] 3. Process limitations: High-temperature processing damages flexible materials, and traditional connection structures cannot adapt to dynamic deformation.

[0006] To this end, a lightweight and flexible composite micro energy storage module is proposed. Summary of the Invention

[0007] The present invention aims to solve the problems raised in the background technology and provides a lightweight flexible composite micro energy storage module.

[0008] The specific technical solutions are as follows:

[0009] A lightweight flexible composite micro energy storage module, comprising:

[0010] A flexible substrate made of a polyurethane-graphene composite material with a thickness of 50-200 μm and a micro-crack structure on the surface;

[0011] The composite electrode layer is formed by alternating stacks of MXene / silicon-carbon composite nanosheets and polypyrrole conductive polymer, wherein the mass ratio of MXene to silicon-carbon is 3:1 to 5:1. The composite electrode layer is directly filled with MXene / silicon-carbon nanosheets into the microcrack structure on the surface of the flexible substrate through vacuum filtration, forming a "barbed" mechanically interlocked three-dimensional porous structure;

[0012] The solid electrolyte layer is composed of a composite of polyethylene oxide (PEO) and lithium salt, embedded with nano-titanium dioxide particles with a thickness of 10-50μm. The solid electrolyte layer is deposited on the surface of the composite electrode layer through an electrospinning process. The nano-titanium dioxide particles are partially embedded in the porous structure of the composite electrode layer, forming a "root-like" ion transmission channel. A transition layer is set at the interface between the composite electrode layer and the solid electrolyte layer. One end of the vertically oriented MXene nanosheets in the transition layer is inserted into the polypyrrole matrix of the composite electrode layer, and the other end penetrates the PEO matrix of the solid electrolyte layer, realizing a dual-path bridge between electrons and ions.

[0013] The encapsulation layer is composed of a composite of polydimethylsiloxane (PDMS) and boron nitride nanosheets, with a thickness of 20-100 μm, and the surface of the encapsulation layer has a gradient hydrophobic structure; the inner layer of the encapsulation layer is hydrophobically modified PDMS, which is covalently connected to the hydroxyl groups (-OH) on the surface of the solid electrolyte layer through siloxane bonds (Si-O-Si); the boron nitride nanosheets on the outer layer of the encapsulation layer are embedded in the PDMS matrix in a parallel stacking manner, and are hot-pressed bonded to the edge of the flexible substrate through a polydopamine adhesive layer to form a "sandwich" fully encapsulated sealing structure.

[0014] In the above-mentioned lightweight flexible composite micro energy storage module, the lateral size of the MXene nanosheets in the composite electrode layer is 1-5 μm, the silicon-carbon composite is a core-shell structure, the silicon core diameter is 50-200 nm, and the carbon shell thickness is 5-20 nm.

[0015] In the above-mentioned lightweight flexible composite micro energy storage module, the particle size of the nano-titanium dioxide particles in the solid electrolyte layer is 10-50 nm, accounting for 5%-15% by mass, and is cross-linked with the PEO matrix through an in-situ ultraviolet polymerization process.

[0016] The above-mentioned lightweight flexible composite micro energy storage module, wherein the gradient hydrophobic structure of the encapsulation layer is: the inner layer contacting the electrolyte side is hydrophobically modified PDMS with a water contact angle >120°, and the outer layer is a hydrophilic boron nitride nanosheet reinforcement layer with a water contact angle <60°. The two are sprayed layer by layer to form an interpenetrating network at the interface.

[0017] The above-mentioned lightweight flexible composite micro energy storage module, wherein the microcrack structure of the flexible substrate is periodically arranged V-shaped grooves with a depth of 10%-30% of the substrate thickness and a spacing of 50-200μm, and the grooves are filled with carbon nanotube / silver nanowire mixed conductive glue.

[0018] The above-mentioned lightweight flexible composite micro energy storage module also includes a connection structure composed of a serpentine metal circuit and a liquid metal eutectic gallium-indium alloy, wherein the curvature radius of the serpentine circuit is less than 100μm, and the liquid metal is filled in the circuit gap to form a self-repairing conductive path.

[0019] The above-mentioned lightweight flexible composite micro energy storage module, wherein the operating voltage window of the composite electrode layer is 0.01-3V (vs. Li / Li+), and the capacitance retention rate is ≥95% after 10,000 bending cycles.

[0020] The above-mentioned lightweight flexible composite micro energy storage module, wherein the overall energy density of the module is ≥150Wh / kg, the thickness is ≤0.5mm, and the internal resistance change rate is <3% in the 180° bending state

[0021] The above-mentioned lightweight flexible composite micro energy storage module, wherein the preparation method of the lightweight flexible composite micro energy storage module comprises the following steps:

[0022] Constructing micro-crack structures on flexible substrates through 3D printing technology;

[0023] The composite electrode layer is deposited on the substrate by using a vacuum filtration-in-situ polymerization alternating process;

[0024] The solid electrolyte layer is coupled to the electrode layer interface by electrospinning;

[0025] The gradient hydrophobic structure of the encapsulation layer is sprayed using microfluidic technology.

[0026] The above-mentioned lightweight flexible composite micro energy storage module, wherein the application of the lightweight flexible composite micro energy storage module is integrated into the energy supply unit of a wearable device, or as a self-powered module of a flexible electronic skin, wherein the module still maintains a stable voltage output when the stretching rate is ≥30%.

[0027] The present invention has the following beneficial effects:

[0028] 1. The micro-crack structure of the flexible substrate and the mechanical interlocking design of the composite electrode layer significantly enhance the interlayer bonding force and improve the structural integrity under dynamic bending. The "root-like" ion transmission channels of the solid electrolyte layer and the vertically oriented transition layer realize the coordinated transmission of electrons and ions through dual pathways, reducing the interface impedance. The gradient hydrophobic structure of the encapsulation layer balances sealing, flexibility and environmental tolerance through chemical bonding and mechanical adaptation, extending the service life of the module.

[0029] 2. By alternating the stacking of MXene / silicon-carbon core-shell structure and polypyrrole in the composite electrode layer, high specific capacity and volume expansion suppression are achieved. The PDMS / boron nitride nanosheet composite system of the encapsulation layer, combined with the gradient hydrophobicity of the inner hydrophobicity and the outer hydrophobicity, achieves directional water vapor management and tear resistance.

[0030] 3. Through the synergy of ultra-thin design and high energy density, it breaks through the thickness limitations of traditional flexible energy storage devices; the electrochemical performance is stable under extreme deformation, bending, and stretching, meeting the application needs of complex scenarios;

[0031] 4. It can be integrated into wearable devices, flexible electronic skin and other fields, adapt to dynamic deformation environments, and provide stable energy supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic structural diagram of a lightweight flexible composite micro energy storage module provided by an embodiment of the present invention;

[0033] Figure 2 A schematic side view of the structure of a lightweight flexible composite micro energy storage module provided by an embodiment of the present invention;

[0034] Figure 3 AA cross-sectional structural diagram of a lightweight flexible composite micro energy storage module provided by an embodiment of the present invention;

[0035] Figure 4 for Figure 3 Schematic diagram of the enlarged structure at B in the middle;

[0036] In the accompanying drawings: 1, flexible substrate; 2, composite electrode layer; 3, solid electrolyte layer; 4, packaging layer; 4a, inner layer; 4b, outer layer. DETAILED DESCRIPTION

[0037] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.

[0038] Among them, the drawings are only used for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting this patent; in order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0039] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "inside", "outside" and the like indicate an orientation or position relationship based on the orientation or position relationship shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0040] In the description of the present invention, unless otherwise expressly specified or limited, when the term "connection" or the like appears to indicate a connection relationship between components, such term should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be internal communication between two components or an interaction between two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood in specific circumstances.

[0041] Example

[0042] The lightweight flexible composite micro energy storage module provided in this embodiment is as follows: Figure 1-Figure 4 As shown, it includes: a flexible substrate 1, a composite electrode layer 2, a solid electrolyte layer 3 and an encapsulation layer 4, wherein:

[0043] The flexible substrate 1 is made of a polyurethane-graphene composite material with a thickness of 50-200 μm and a micro-crack structure on the surface;

[0044] The composite electrode layer 2 is formed by alternating stacks of MXene / silicon-carbon composite nanosheets and polypyrrole conductive polymer, wherein the mass ratio of MXene to silicon-carbon is 3:1 to 5:1. The composite electrode layer 2 is directly filled with MXene / silicon-carbon nanosheets into the microcrack structure on the surface of the flexible substrate 1 by vacuum filtration, forming a "barbed" mechanically interlocked three-dimensional porous structure;

[0045] The solid electrolyte layer 3 is composed of a composite of polyethylene oxide (PEO) and lithium salt, embedded with nano-titanium dioxide particles, and has a thickness of 10-50 μm. The solid electrolyte layer 3 is deposited on the surface of the composite electrode layer 2 through an electrospinning process. The nano-titanium dioxide particles are partially embedded in the porous structure of the composite electrode layer 2, forming "root-like" ion transmission channels. A transition layer is provided at the interface between the composite electrode layer 2 and the solid electrolyte layer 3. One end of the vertically oriented MXene nanosheets in the transition layer is inserted into the polypyrrole matrix of the composite electrode layer 2, and the other end penetrates the PEO matrix of the solid electrolyte layer 3, realizing a dual-pathway bridge between electrons and ions.

[0046] The encapsulation layer 4 is composed of a composite of polydimethylsiloxane (PDMS) and boron nitride nanosheets, with a thickness of 20-100 μm, and the surface of the encapsulation layer 4 has a gradient hydrophobic structure; the inner layer 4a of the encapsulation layer 4 is a hydrophobically modified PDMS, which is covalently connected to the hydroxyl groups (-OH) on the surface of the solid electrolyte layer 3 through a siloxane bond (Si-O-Si); the boron nitride nanosheets of the outer layer 4b of the encapsulation layer 4 are embedded in the PDMS matrix in a parallel stacking manner, and are hot-pressed bonded to the edge of the flexible substrate 1 through a polydopamine adhesive layer to form a "sandwich" fully encapsulated sealing structure.

[0047] The lightweight flexible composite micro-energy storage module adopts the above technical solution. Through the micro-crack structure on the surface of the flexible substrate 1 and the mechanical interlocking design of the composite electrode layer 2, it significantly enhances the interfacial bonding force between the substrate and the electrode, thereby improving the structural stability of the module under dynamic bending. The MXene / silicon carbon-polypyrrole alternating stacked electrodes are combined with a three-dimensional porous structure to achieve synergistic optimization of high specific surface area and fast ion / electron transmission paths, thereby improving energy storage efficiency. The "root-like" coupling interface between the solid electrolyte layer 3 and the electrode is achieved through nanoparticle embedding and a vertically oriented transition layer, which reduces the interfacial impedance and inhibits dendrite growth. The gradient hydrophobic encapsulation layer achieves a balance between sealing, environmental tolerance and flexibility through chemical bonding and mechanical adaptation design, thereby extending the service life of the module.

[0048] Specifically, in this embodiment, the lateral size of the MXene nanosheets in the composite electrode layer 2 is 1-5 μm, the silicon-carbon composite is a core-shell structure, the silicon core diameter is 50-200 nm, and the carbon shell thickness is 5-20 nm.

[0049] Using the above technical solution, the lateral size control of MXene nanosheets (1-5μm) ensures that they form a continuous conductive network while avoiding brittle fracture caused by excessive size; the silicon-carbon core-shell structure effectively alleviates the volume expansion problem of silicon by coating the silicon core with a carbon shell, thereby improving the cycle stability of the electrode.

[0050] Specifically, in this embodiment, the particle size of the nano-titanium dioxide particles in the solid electrolyte layer 3 is 10-50 nm, accounting for 5%-15% by mass, and is cross-linked with the PEO matrix through an in-situ ultraviolet polymerization process.

[0051] Using the above technical solution, the introduction of nano-titanium dioxide particles enhances the mechanical strength of the solid electrolyte, and at the same time acts as an ion conduction promoter to optimize the lithium ion migration path; the in-situ UV polymerization process achieves uniform cross-linking of the nanoparticles and the PEO matrix, improving the interfacial compatibility between the electrolyte layer and the electrode.

[0052] Specifically, in this embodiment, the gradient hydrophobic structure of the encapsulation layer 4 is as follows: the side of the inner layer 4a contacting the electrolyte is hydrophobically modified PDMS with a water contact angle of >120°, and the outer layer 4b is a hydrophilic boron nitride nanosheet reinforcement layer with a water contact angle of <60°. The two are sprayed layer by layer to form an interpenetrating network at the interface.

[0053] With the above technical solution, the gradient hydrophobic structure (hydrophobic inside + hydrophilic outside) significantly improves the stability of the module in a humid environment through directional water vapor management (outer layer adsorption / inner layer barrier); the interpenetrating network at the interface enhances the bonding strength between the inner layer 4a and the outer layer 4b of the encapsulation layer, avoiding interface stratification caused by differences in mechanical properties.

[0054] Specifically, in this embodiment, the microcrack structure of the flexible substrate 1 is periodically arranged V-shaped grooves with a depth of 10%-30% of the substrate thickness and a spacing of 50-200 μm, and the grooves are filled with carbon nanotube / silver nanowire mixed conductive paste.

[0055] Using the above technical solution, periodic V-shaped micro-crack grooves disperse bending stress through geometric design, reducing the risk of substrate cracking; carbon nanotube / silver nanowire mixed conductive glue is filled to form a cross-layer conductive path, improving the electron transmission efficiency between the substrate and the electrode.

[0056] Specifically, in this embodiment, a connection structure is also included, which is composed of a serpentine metal circuit and a liquid metal eutectic gallium-indium alloy, wherein the curvature radius of the serpentine circuit is less than 100 μm, and the liquid metal is filled in the circuit gap to form a self-repairing conductive path.

[0057] The crest / trough micropores of the serpentine metal circuit allow the liquid metal to form a vertical and horizontal bidirectional conductive network. Compared with traditional planar wiring, the conductive area is greatly increased. When bending, the liquid metal flows to compensate for deformation stress, significantly reducing the resistance change rate.

[0058] The design of embedding the circuit in the outer layer 4b of the packaging layer utilizes the high thermal conductivity (>50W / m·K) of the boron nitride nanosheets to assist in heat dissipation and avoid local overheating caused by current concentration.

[0059] Using the above technical solution, the serpentine metal circuit and liquid metal composite connection structure ensure that the module maintains a stable electrical connection under extreme deformation through curvature radius optimization and self-healing properties; the fluidity of liquid metal fills the gaps, avoiding the breakage problem of traditional rigid circuits.

[0060] The preparation process of the connection structure is as follows:

[0061] Step A: Laser direct writing of serpentine metal circuits on the surface of the outer layer 4b of the packaging layer 4 and simultaneous etching of microholes;

[0062] Step B: Inject liquid metal into micropores and circuit gaps, and solidify in a vacuum environment at 60°C to form a continuous path;

[0063] Step C: electroplating gold-graphene bumps on the connection ends through a mask plate;

[0064] Step D: Bonding the end of the connection structure to the conductive adhesive of the flexible substrate 1 by low-temperature hot pressing to complete the module-external circuit integration.

[0065] Specifically, in this embodiment, the operating voltage window of the composite electrode layer 2 is 0.01-3 V (vs. Li / Li+), and the capacitance retention rate is ≥95% after 10,000 bending cycles.

[0066] Using the above technical solution, the wide operating voltage window (0.01-3V) is compatible with high energy density and high power density requirements, expanding the application scenarios of the module; the ultra-high bending cycle stability (capacitance retention rate ≥ 95%) verifies the reliability of the full-chain structural design of electrode-electrolyte-packaging.

[0067] Specifically, in this embodiment, the overall energy density of the module is ≥150Wh / kg, the thickness is ≤0.5mm, and the internal resistance change rate is <3% in a 180° bending state.

[0068] By adopting the above technical solution, ultra-thinness and high energy density are achieved in synergy, breaking through the technical bottleneck of "thick and inefficient" traditional flexible energy storage devices; the stable internal resistance in the bending state indicates that the mechanical-electrical coupling design between the layers inside the module effectively suppresses the performance degradation caused by deformation.

[0069] Specifically, in this embodiment, the method for preparing the lightweight flexible composite micro energy storage module includes the following steps:

[0070] constructing a micro-crack structure of the flexible substrate 1 by 3D printing technology;

[0071] Depositing a composite electrode layer 2 on the substrate using a vacuum filtration-in-situ polymerization alternating process;

[0072] The solid electrolyte layer 3 is coupled to the electrode layer interface by electrospinning;

[0073] The gradient hydrophobic structure of the encapsulation layer 4 is sprayed using microfluidic technology.

[0074] By adopting the above technical solution, full low-temperature processing is achieved through the 3D printing + vacuum filtration - in-situ polymerization + electrospinning + microfluidic spraying process chain, avoiding damage to flexible materials caused by high temperature; through the precise matching of process steps and structural design, the interface quality and performance controllability of each functional layer (substrate, electrode, electrolyte, packaging) are ensured.

[0075] Specifically, in this embodiment, the lightweight flexible composite micro energy storage module is integrated into the energy supply unit of a wearable device, or used as a self-powered module for flexible electronic skin, wherein the module maintains a stable voltage output when the stretching rate is ≥30%.

[0076] Using the above technical solution, the adaptability of the module integrated with wearable devices and electronic skin is verified in extreme environments (such as stretching, bending, humidity and heat); the stretch-stable power supply characteristics reflect the electrochemical-mechanical collaborative design advantages of the module under complex deformation, meeting the energy supply needs of the next generation of flexible electronic devices.

[0077] In summary, the vehicle-mounted energy system with replaceable battery boxes provided in this embodiment has the following advantages:

[0078] 1. The microcrack structure of the flexible substrate 1 and the mechanical interlocking design of the composite electrode layer 2 significantly enhance interlayer bonding and improve structural integrity under dynamic bending. The "root-like" ion transmission channels of the solid electrolyte layer 3 and the vertically oriented transition layer achieve dual-pathway coordinated electron-ion transmission, reducing interfacial impedance. The gradient hydrophobic structure of the encapsulation layer 4 balances sealing, flexibility, and environmental tolerance through chemical bonding and mechanical adaptation, extending the module's service life.

[0079] 2. The alternating stacking of MXene / silicon-carbon core-shell structure and polypyrrole in the composite electrode layer 2 achieves both high specific capacity and volume expansion suppression. The PDMS / boron nitride nanosheet composite system in the encapsulation layer 4, combined with the gradient hydrophobicity of the inner and outer hydrophobicity, achieves directional water vapor management and tear resistance.

[0080] 3. Through the synergy of ultra-thin design and high energy density, it breaks through the thickness limitations of traditional flexible energy storage devices; the electrochemical performance is stable under extreme deformation, bending, and stretching, meeting the application needs of complex scenarios;

[0081] 4. It can be integrated into wearable devices, flexible electronic skin and other fields, adapt to dynamic deformation environments, and provide stable energy supply.

[0082] Overall working principle process

[0083] 1. Preparation process:

[0084] 1.1 Flexible substrate 1 constructs microcrack structure through 3D printing;

[0085] 1.2 Composite electrode layer 2 uses vacuum filtration-in-situ polymerization process to form a three-dimensional porous interlocking structure on the substrate surface;

[0086] 1.3 The solid electrolyte layer 3 is coupled with the electrode layer through electrospinning, and a vertically oriented transition layer is generated at the interface;

[0087] 1.4 The encapsulation layer 4 is sprayed with a gradient hydrophobic structure through microfluidics and is sealed by hot pressing and bonding with the edge of the substrate.

[0088] 2. Working process:

[0089] 2.1 Charging and discharging stage: Lithium ions are transported through the root-like channels of the solid electrolyte layer 3, and electrons are conducted through the MXene network of the composite electrode layer 2, achieving efficient energy storage;

[0090] 2.2 Deformation adaptation: The microcracks of the flexible substrate 1 disperse stress, the gradient structure of the encapsulation layer 4 absorbs deformation energy, and the liquid metal self-healing properties of the connection structure 5 maintain the stability of the conductive path.

[0091] The above are only preferred embodiments of the present invention and do not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A lightweight flexible composite micro energy storage module, characterized in that: include: A flexible substrate (1) is made of a polyurethane-graphene composite material, has a thickness of 50-200 μm, and has a microcrack structure on the surface; The composite electrode layer (2) is formed by alternately stacking MXene / silicon-carbon composite nanosheets and polypyrrole conductive polymer, wherein the mass ratio of MXene to silicon-carbon is 3:1 to 5:1, and the composite electrode layer (2) directly fills the MXene / silicon-carbon nanosheets into the microcrack structure on the surface of the flexible substrate (1) by vacuum filtration to form a "barbed" mechanically interlocked three-dimensional porous structure; The solid electrolyte layer (3) is composed of a composite of polyethylene oxide (PEO) and lithium salt, and is embedded with nano-titanium dioxide particles, with a thickness of 10-50 μm. The solid electrolyte layer (3) is deposited on the surface of the composite electrode layer (2) through an electrostatic spinning process, and the nano-titanium dioxide particles are partially embedded in the porous structure of the composite electrode layer (2), forming a "root-like" ion transmission channel; a transition layer is provided at the interface between the composite electrode layer (2) and the solid electrolyte layer (3), and one end of the vertically oriented MXene nanosheets in the transition layer is inserted into the polypyrrole matrix of the composite electrode layer (2), and the other end penetrates the PEO matrix of the solid electrolyte layer (3), thereby realizing a dual-path bridge between electrons and ions; The encapsulation layer (4) is composed of a composite of polydimethylsiloxane (PDMS) and boron nitride nanosheets, has a thickness of 20-100 μm, and has a gradient hydrophobic structure on the surface of the encapsulation layer (4); the inner layer (4a) of the encapsulation layer (4) is hydrophobically modified PDMS, which is covalently connected to the hydroxyl groups (-OH) on the surface of the solid electrolyte layer (3) through siloxane bonds (Si-O-Si); the boron nitride nanosheets of the outer layer (4b) of the encapsulation layer (4) are embedded in the PDMS matrix in a parallel stacking manner, and are hot-pressed bonded to the edge of the flexible substrate (1) through a polydopamine adhesive layer to form a "sandwich" type fully encapsulated sealing structure.

2. The lightweight flexible composite micro energy storage module according to claim 1, characterized in that: The lateral size of the MXene nanosheets in the composite electrode layer (2) is 1-5 μm, the silicon-carbon composite is a core-shell structure, the silicon core diameter is 50-200 nm, and the carbon shell thickness is 5-20 nm.

3. The lightweight flexible composite micro energy storage module according to claim 1, characterized in that: The nano-titanium dioxide particles in the solid electrolyte layer (3) have a particle size of 10-50 nm and a mass proportion of 5%-15%, and are cross-linked with the PEO matrix through an in-situ ultraviolet polymerization process.

4. The lightweight flexible composite micro energy storage module according to claim 1, characterized in that: The gradient hydrophobic structure of the encapsulation layer (4) is as follows: the side of the inner layer (4a) contacting the electrolyte is hydrophobically modified PDMS with a water contact angle of >120°, and the outer layer (4b) is a hydrophilic boron nitride nanosheet reinforcement layer with a water contact angle of <60°, and the two are sprayed layer by layer to form an interfacial interpenetrating network.

5. The lightweight flexible composite micro energy storage module according to claim 1, characterized in that: The microcrack structure of the flexible substrate (1) is periodically arranged V-shaped grooves with a depth of 10%-30% of the substrate thickness and a spacing of 50-200 μm, and the grooves are filled with carbon nanotube / silver nanowire mixed conductive glue.

6. The lightweight flexible composite micro energy storage module according to claim 1, characterized in that: It also includes a connection structure consisting of a serpentine metal line and a liquid metal eutectic gallium-indium alloy, wherein the curvature radius of the serpentine line is less than 100 μm, and the liquid metal is filled in the gap between the lines to form a self-repairing conductive path.

7. The lightweight flexible composite micro energy storage module according to claim 1, characterized in that: The operating voltage window of the composite electrode layer (2) is 0.01-3V (vs. Li / Li+), and the capacitance retention rate is ≥95% after 10,000 bending cycles.

8. The lightweight flexible composite micro energy storage module according to claim 1, characterized in that: The overall energy density of the module is ≥150Wh / kg, the thickness is ≤0.5mm, and the internal resistance change rate is <3% in a 180° bending state.

9. The lightweight flexible composite micro energy storage module according to claim 1, characterized in that: The preparation method of the lightweight flexible composite micro energy storage module comprises the following steps: constructing a microcrack structure of a flexible substrate (1) by 3D printing technology; Depositing a composite electrode layer (2) on a substrate by using a vacuum filtration-in-situ polymerization alternating process; coupling the solid electrolyte layer (3) to the electrode layer interface by electrostatic spinning; The gradient hydrophobic structure of the encapsulation layer (4) is sprayed using microfluidic technology.

10. The lightweight flexible composite micro energy storage module according to claim 1, characterized in that: The application of this lightweight flexible composite micro energy storage module is integrated into the energy supply unit of wearable devices, or as a self-powered module for flexible electronic skin, where the module still maintains a stable voltage output when the stretching rate is ≥30%.

Images