Composite enhanced three-dimensional structure solid-state battery and preparation method thereof

Abstract

The invention provides a composite enhanced three-dimensional structure solid-state battery and a preparation method thereof, and belongs to the technical field of new energy batteries and composite materials. The battery with the structure integrates energy storage and force bearing, and comprises a positive electrode, a negative electrode, a solid electrolyte positioned between the positive electrode and the negative electrode, and a three-dimensional conductive support frame penetrating through the interior of the battery. The specific capacity, the rate capability, the cycle life and the mechanical property of the battery are remarkably improved by doping modified elements in an electrode material, grafting functional macromolecules at an interface, adopting a carbon nanotube / ceramic / polymer multi-component composite electrode and constructing a porous three-dimensional conductive network. The battery is particularly suitable for the fields of aerospace, electric automobiles, portable flexible electronics and the like, the weight of a system can be greatly reduced, and the safety and the reliability are improved.

Description

Technical Field

[0001] This invention relates to the field of new energy batteries and composite materials technology, and in particular to a composite reinforced three-dimensional solid-state battery and its preparation method. Background Technology

[0002] With the development of electric transportation, aerospace, and wearable devices, higher requirements have been placed on batteries for energy density, power density, and safety and reliability. However, traditional lithium-ion batteries are usually packaged independently and installed in devices, taking up space and adding extra weight. In fields such as aerospace, the separation of structural components and batteries leads to weight redundancy. Therefore, the concept of "structural batteries" has emerged, combining battery function with a load-bearing structure, enabling the battery itself to perform both energy storage and mechanical support functions. Existing research has attempted to embed batteries in structures such as carbon fiber composites, for example, using carbon fiber as battery electrodes or current collectors, thereby providing energy storage while partially bearing structural loads. However, existing structural batteries still have limitations in terms of energy density and mechanical performance: on the one hand, to ensure mechanical strength, thick structural materials are often used, leading to a decrease in energy storage capacity per unit weight; on the other hand, volume changes and interfacial stresses in battery materials during charging and discharging can easily cause structural damage, affecting cycle life.

[0003] On the other hand, all-solid-state batteries, due to their use of solid electrolytes, offer advantages such as non-flammability, high safety, and good thermal stability, making them increasingly important in the electric vehicle and aerospace fields. However, all-solid-state batteries also face some technical challenges, including: low room-temperature ionic conductivity of solid electrolytes, high resistance due to poor interfacial contact, slow lithium-ion transport at the interface, and interfacial separation caused by the expansion stress of electrode materials during cycling. In particular, when using inorganic oxide solid electrolytes, the material's high rigidity makes it difficult to achieve a perfect interfacial fit with the electrodes; while sulfide electrolytes with high ionic conductivity, although soft and easy to compact, are extremely sensitive to moisture, posing a potential stability risk.

[0004] In summary, current technologies lack a structural battery solution that can simultaneously improve both electrochemical and mechanical performance. How to construct a three-dimensional reinforced structure within the battery to support mechanical loads, while simultaneously improving the conductivity and cycle stability of solid-state batteries through material modification and composite design, has become a pressing technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a composite-enhanced three-dimensional solid-state battery and its preparation method, in order to solve the above-mentioned technical problems.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a composite-enhanced three-dimensional solid-state battery, comprising a composite positive electrode layer, a negative electrode layer, a solid electrolyte layer, and a three-dimensional conductive support frame; The three-dimensional conductive support frame penetrates both the composite positive electrode layer and the negative electrode layer; A functional polymer interface layer is provided between the composite positive electrode layer and the solid electrolyte layer, and a functional polymer interface layer is provided between the negative electrode layer and the solid electrolyte layer. The functional polymer interface layer is prepared from a polymer containing polar functional groups; The solid electrolyte layer is prepared from a solid electrolyte, which includes an oxide solid electrolyte, a sulfide solid electrolyte, or a polymer solid electrolyte. The solid electrolyte contains 0.1 to 5 mol% of doping elements based on the amount of substance of the solid electrolyte, and the doping elements include one or more of aluminum, gallium, yttrium and tantalum.

[0007] Furthermore, the composite cathode layer is prepared from a multi-component cathode material; The raw material system of the multi-component positive electrode material includes electrode active material, conductive additive, solid electrolyte and polymer binder; The electrode active material of the composite positive electrode layer includes layered oxides, lithium-rich manganese-based materials, LiFePO4 powder, or spinel-type LiMn2O4 powder. The mass ratio of the electrode active material, conductive additive, solid electrolyte, and polymer binder is independently 0.65~0.8:0.02~0.05:0.1~0.18:0.08~0.15.

[0008] Furthermore, the negative electrode layer is prepared from a multi-component negative electrode material; The raw material system of the multi-component negative electrode material includes electrode active material, conductive additive, solid electrolyte and polymer binder; The electrode active material includes graphite, carbon fiber, silicon-based material, or tin-based material.

[0009] Furthermore, the negative electrode layer can also be lithium foil, graphene-modified graphite, or lithium titanate.

[0010] Furthermore, the conductive additive includes carbon nanotubes, graphene, or conductive carbon black. The polymer binder includes polyvinylidene fluoride, polyether binders, or acrylonitrile copolymer binders.

[0011] Furthermore, in the multi-component negative electrode material, the mass ratio of electrode active material, conductive additive, solid electrolyte and polymer binder is independently 0.65~0.8:0.02~0.05:0.1~0.18:0.08~0.15.

[0012] Furthermore, based on the amount of substance of the electrode active material, the electrode active material contains 0.1 to 5 mol% of doping elements, wherein the doping elements include one or more of aluminum, magnesium, titanium, zirconium, and boron.

[0013] Furthermore, the three-dimensional conductive support frame has a porous structure, and its materials include metal foam, metal fiber felt, three-dimensional printed metal skeleton, carbon foam, graphene skeleton or carbon fiber fabric. The porosity of the three-dimensional conductive support frame is 30~90%, and the volume conductivity is ≥10^4S / m.

[0014] The present invention also provides a method for preparing the above-mentioned composite-enhanced three-dimensional solid-state battery, comprising the following steps: Step 1) Mix the electrode active material, conductive additive, polymer binder and solid electrolyte to obtain a positive electrode slurry. Coat the positive electrode slurry on one side of the three-dimensional conductive support frame and cure to form a composite positive electrode layer. Step 2) Prepare a solid electrolyte layer on the composite positive electrode layer by hot pressing or sintering. Step 3) A negative electrode layer is formed on the other side of the three-dimensional conductive support frame by means of melt infiltration, pressing and bonding, or coating and curing. Step 4) Introduce functional polymer interface materials at the interface of the composite positive electrode layer, negative electrode layer and solid electrolyte layer to form a functional polymer interface layer. Encapsulate the resulting battery assembly and perform hot-press curing treatment to obtain a composite reinforced three-dimensional solid battery.

[0015] Furthermore, the composite-enhanced three-dimensional solid-state battery is fabricated into plate-like or shell-like structural components for use as the skin structure of drones or aircraft.

[0016] The beneficial effects of this invention are: Improved weight and volumetric efficiency: The integrated design of the structure and battery function eliminates the need for separate battery packaging and redundant support components, reducing the overall system weight by more than 15% and improving volume utilization. Applications in aircraft and electric vehicles can significantly enhance driving range.

[0017] Improved energy density and specific capacity: The multi-component composite electrode and three-dimensional structure increase the loading and utilization of active materials in the electrode, thereby increasing the battery specific capacity by about 10-20%. The energy density of the whole battery can preferably reach 150-200Wh / kg, which is better than ordinary composite battery schemes.

[0018] Enhanced power density and fast charging performance: The built-in three-dimensional conductive network significantly reduces the battery's internal resistance, resulting in improved high-rate charge and discharge performance. Experiments show that even at a 10C high-current discharge, the battery of this invention can still output more than 90% of its initial capacity, while traditional planar batteries achieve less than 60%. This battery can be charged to 80% in 5 minutes, demonstrating excellent fast charging capabilities.

[0019] Extended cycle life: Material doping and interface enhancement measures effectively mitigate material degradation and interface failure during cycling. Compared with batteries that do not employ the enhancement technology of this invention, the capacity retention rate after 500 cycles increases from 80% to over 95%, and the capacity decay rate is significantly reduced.

[0020] Improved safety and reliability: The use of a solid-state electrolyte eliminates the risk of leakage from flammable liquid electrolytes, and improved interface stability reduces the possibility of lithium dendrite formation. The battery did not experience short circuits or thermal runaway during abuse tests such as puncture and crushing. Expanded temperature range adaptability allows for stable operation in environments ranging from -30°C to 60°C.

[0021] Excellent mechanical properties: The internal three-dimensional support frame and reinforced interface significantly improve the overall mechanical strength of the battery. In a three-point bending test, the bending strength of the battery laminate integrating this invention's structure increased by more than 30%. The battery can withstand the vibrations and impacts during spacecraft launch, demonstrating good structural integrity. Detailed Implementation

[0022] This invention provides a composite-enhanced three-dimensional solid-state battery, comprising a composite positive electrode layer, a negative electrode layer, a solid electrolyte layer, and a three-dimensional conductive support frame; The three-dimensional conductive support frame penetrates both the composite positive electrode layer and the negative electrode layer; A functional polymer interface layer is provided between the composite positive electrode layer and the solid electrolyte layer, and a functional polymer interface layer is provided between the negative electrode layer and the solid electrolyte layer. The functional polymer interface layer is prepared from a polymer containing polar functional groups; The solid electrolyte layer is prepared from a solid electrolyte, which includes an oxide solid electrolyte, a sulfide solid electrolyte, or a polymer solid electrolyte. The solid electrolyte contains 0.1 to 5 mol% of doping elements based on the amount of substance of the solid electrolyte, and the doping elements include one or more of aluminum, gallium, yttrium and tantalum.

[0023] In this invention, the three-dimensional conductive support framework, the doped solid electrolyte, and the functional polymer interface layer work together to enable the battery to retain ≥90% of its capacity after 500 cycles and maintain normal charge and discharge functions under three-point bending load.

[0024] In this invention, the functional polymer interface layer is prepared from a functional polymer, which is preferably a polymer material containing polar functional groups, and more preferably polyethylene glycol, polyacrylic acid or polyvinyl sulfonic acid.

[0025] In this invention, the interfacial polymer forms a stable interfacial film by hydrogen bonding or coordination with the inorganic surface through functional groups, while the polymer backbone provides a certain degree of flexibility to alleviate interfacial stress.

[0026] In this invention, the selection of the interface polymer is optimized based on the properties of the solid electrolyte and the electrode material. For oxide electrolyte interfaces, a polymer coating containing phosphate ester groups is preferably used to improve wettability, while for sulfide electrolyte interfaces, a polymer containing polysulfide or lithium carboxylate salt is preferably used to reduce interfacial impedance.

[0027] In this invention, the solid electrolyte is preferably an oxide solid electrolyte or a sulfide solid electrolyte.

[0028] In this invention, the sulfide solid electrolyte is preferably a sulfide glass or a crystalline sulfide.

[0029] In this invention, the oxide solid electrolyte is preferably a garnet structure or a NASICON structure.

[0030] In this invention, the solid electrolyte preferably contains 0.5 to 3 mol% of doping elements; the doping elements are preferably one or more of aluminum, gallium and tantalum, and more preferably aluminum.

[0031] In this invention, the purpose of doping elements into the solid electrolyte is to stabilize the cubic phase LLZO, improve ionic conductivity, and increase carrier concentration to enhance conductivity.

[0032] In this invention, the three-dimensional conductive support frame is preferably made of metal and / or carbon-based materials, and more preferably of nickel foam, copper foam, aluminum honeycomb, continuous carbon fiber bundles, carbon nanotube sponge or three-dimensional graphene foam.

[0033] In this invention, the three-dimensional conductive support frame serves as both the current collector and load-bearing skeleton of the battery, enabling the manufactured battery assembly to have excellent bending strength and high energy density when parallel to the battery surface.

[0034] In this invention, the composite cathode layer is prepared from a multi-component cathode material; The raw material system of the multi-component positive electrode material includes electrode active material, conductive additive, solid electrolyte and polymer binder; The electrode active material of the composite positive electrode layer includes layered oxides, lithium-rich manganese-based materials, LiFePO4 powder, or spinel-type LiMn2O4 powder.

[0035] In this invention, in the multi-component positive electrode material, the mass ratio of electrode active material, conductive additive, solid electrolyte and polymer binder is independently 0.65~0.8:0.02~0.05:0.1~0.18:0.08~0.15, preferably 0.7:0.04:0.15:0.1.

[0036] In this invention, the negative electrode layer is prepared from a multi-component negative electrode material; The raw material system of the multi-component negative electrode material includes electrode active material, conductive additive, solid electrolyte and polymer binder; The electrode active material includes graphite, carbon fiber, silicon-based material or tin-based material, preferably graphite, carbon fiber or silicon-based material, and more preferably graphite.

[0037] In this invention, the negative electrode layer may also be lithium foil, graphene-modified graphite, or lithium titanate, preferably graphene-modified graphite.

[0038] In this invention, the conductive additive includes carbon nanotubes, graphene, or conductive carbon black, preferably conductive carbon black; The polymer binder includes polyvinylidene fluoride, polyether binders, or acrylonitrile copolymer binders, preferably polyvinylidene fluoride.

[0039] In this invention, the mass ratio of the electrode active material, conductive additive, solid electrolyte and polymer binder in the multi-component negative electrode material is independently 0.65~0.8:0.02~0.05:0.1~0.18:0.08~0.15, preferably 0.7:0.04:0.15:0.1.

[0040] In this invention, the electrode active material contains 0.1 to 5 mol% of doping elements, preferably 0.5 to 3 mol%, based on the amount of substance of the electrode active material; the doping elements include one or more of aluminum, magnesium, titanium, zirconium and boron, preferably one or more of aluminum, magnesium and titanium, and more preferably aluminum.

[0041] In this invention, by introducing appropriate amounts of doping elements into the lattice of the positive electrode active material, the crystal structure is stabilized, the lattice stress is reduced, or the doping at the grain boundaries is increased to prevent phase transitions and particle growth, thereby stabilizing the material structure, inhibiting the formation of harmful phases, and improving cycle life and high-temperature performance.

[0042] In this invention, the three-dimensional conductive support frame has a porous structure, and its material includes metal foam, metal fiber felt, three-dimensional printed metal skeleton, carbon foam, graphene skeleton or carbon fiber fabric, preferably metal foam, metal fiber felt, three-dimensional printed metal skeleton or carbon foam. The porosity of the three-dimensional conductive support frame is 30-90%, preferably 50-80%; the volume conductivity is preferably ≥10^4 S / m.

[0043] The present invention also provides a method for preparing the above-mentioned composite-enhanced three-dimensional solid-state battery, comprising the following steps: Step 1) Mix the electrode active material, conductive additive, polymer binder and solid electrolyte to obtain a positive electrode slurry. Coat the positive electrode slurry on one side of the three-dimensional conductive support frame and cure to form a composite positive electrode layer. Step 2) Prepare a solid electrolyte layer on the composite positive electrode layer by hot pressing or sintering. Step 3) A negative electrode layer is formed on the other side of the three-dimensional conductive support frame by means of melt infiltration, pressing and bonding, or coating and curing. Step 4) Introduce functional polymer interface materials at the interface of the composite positive electrode layer, negative electrode layer and solid electrolyte layer to form a functional polymer interface layer. Encapsulate the resulting battery assembly and perform hot-press curing treatment to obtain a composite reinforced three-dimensional solid battery.

[0044] In this invention, the composite-enhanced three-dimensional solid-state battery is fabricated into a plate-like or shell-like structural component and used as the skin structure of a drone or aircraft.

[0045] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0046] Example 1

[0047] 1 mol% aluminum nitrate was added to NCM811, and the electrode active material was obtained by high-temperature solid-state sintering at 800℃. Based on the mass fraction of the electrode active material, 10 wt% LLZTO (lithium lanthanum zirconium titanium oxide) powder, 5 wt% carbon nanotube conductive agent, 8 wt% polyvinylidene fluoride binder, and the obtained electrode active material were mixed, and N-methylpyrrolidone was added to prepare a slurry. The slurry was uniformly coated onto one side of a nickel foam frame, scraped to penetrate into the pores inside the foam, and vacuum dried. It was then compacted at 60℃ to form a composite positive electrode layer with a thickness of 200 μm. A 50 μm thick Al-doped LLZTO solid electrolyte film is laid on the composite positive electrode layer. A lithium metal foil is pressed onto the other side of the solid electrolyte film as the negative electrode, and a liquid Ga-In eutectic alloy is coated on the surface of the nickel foam frame on this side. A layer of mercapto-modified polyethylene glycol is coated between the composite positive electrode layer and the solid electrolyte layer, and a layer of polyacrylonitrile-based gel (doped with 0.8 wt% LiTFSI salt) with a thickness of 5 μm is coated between the negative electrode layer and the solid electrolyte layer to obtain a composite-enhanced three-dimensional solid-state battery.

[0048] Performance Tests and Results

[0049] The assembled battery was subjected to electrochemical testing without external mechanical stress. The initial discharge specific capacity at room temperature was measured to be 168 mAh / g (based on the positive electrode active material), an 8% increase compared to the 155 mAh / g of the undoped control battery (undoped NCM811 positive electrode + undoped LLZTO electrolyte). After 300 charge-discharge cycles at 1C, the capacity retention reached 94%, significantly better than the 81% of the control battery. EIS AC impedance testing showed that the interfacial resistance of the doped battery was approximately 120 Ω·cm. 2 It was significantly lower than the control group's 250 Ω·cm 2 This demonstrates that doping improves interfacial ionic conductivity. After storing both sets of batteries at 45°C for four weeks, the doped battery showed no significant capacity decay, while the control battery experienced a 5% capacity decay, indicating that doping helps suppress material performance degradation at high temperatures.

[0050] Mechanical performance test and results

[0051] To evaluate structural performance, the battery was clamped between two aluminum plates and fixed with a preload of 1 MPa, followed by a three-point bending test. The doped enhanced battery sample maintained structural integrity and normal operation even at a bending moment of 20 N·m, while the undoped control battery showed signs of positive electrode layer cracking and rapid capacity decay at 15 N·m. This indicates that the doping in this embodiment makes the electrode material more stable, and the three-dimensional framework significantly improves the mechanical load-bearing capacity.

[0052] Example 2

[0053] LiFePO4 (LFP) powder with a particle size of 500 nm was selected as the positive electrode active material. A layer of graphene was chemically vapor-deposited on the graphite surface, and the resulting graphene-modified graphite was used as the negative electrode material. The solid electrolyte was a PEO-based polymer electrolyte: polyethylene glycol dimethyl ether with a molecular weight of 1000 was mixed with lithium LiTFSI at a molar ratio of ethylene oxide:Li of 20:1, and 5 wt% nano-SiO2 was added as a reinforcing filler to prepare a polymer gel electrolyte membrane with ionic conductivity.

[0054] Conductive carbon nanofiber cloth was selected as the supporting skeleton. Based on the mass fraction of the positive electrode material, 5 wt% of SuperP conductive carbon black, 8 wt% of PVDF binder and LFP positive electrode material were mixed and coated on one side of the carbon nanofiber cloth to form a positive electrode layer with a thickness of 50 μm. Graphene-modified graphite negative electrode slurry was coated on the other side of the carbon nanofiber cloth to form a negative electrode layer with a thickness of 50 μm.

[0055] A sodium polyacrylate solution is coated between the composite positive electrode layer and the solid electrolyte layer, and a polystyrene-polyethylene glycol block copolymer is coated between the negative electrode layer and the solid electrolyte layer. After vacuum drying at 60°C, the interfacial polymer is cured on the electrode surface to form a coating with a thickness of 1 μm.

[0056] The resulting polymer gel electrolyte membrane is sandwiched between the positive and negative electrode layers, stacked, and gently pressed to adhere them. Finally, the entire assembly is encapsulated in a polyester film to prevent water and oxygen intrusion, thus obtaining a flexible battery structure.

[0057] Tests and Results

[0058] The prepared flexible battery structure was subjected to bending and electrochemical performance tests. First, it was cycled at 0.2C at room temperature, with an initial discharge capacity of 148 mAh / g (based on LFP). After 50 cycles, the capacity retention was 98%, demonstrating excellent early cycle stability. Compared to the control group without the interface polymer (which retained 90% after 50 cycles), the interface stability of this embodiment was significantly improved. EIS testing showed that the interface resistance of the battery in this embodiment was 150 Ω·cm. 2 It is much lower than the control group's 300 Ω·cm 2 This indicates that the functional polymer interface layer effectively reduces the interface impedance.

[0059] Flexibility performance testing

[0060] The battery sample was bent to a radius of 30 mm and subjected to 100 consecutive bends. Capacity was then tested, showing no significant decrease, with a capacity retention rate of 95%. In contrast, the control battery, after the same bending test, only retained 70% of its capacity, and its interfacial impedance increased by more than 50%. Further tensile testing involved 1000 cycles of tension at 0–1% cyclic strain. The battery in this embodiment showed no significant change in internal resistance and no delamination between internal layers. This indicates that the grafted functional polymer not only enhances the adhesion of the solid-state battery interface but also imparts flexibility and fatigue resistance, enabling it to withstand repeated mechanical deformation with almost no performance degradation.

[0061] Example 3

[0062] NCM622 (LiNi with an average particle size of 10 μm) was mixed at a mass ratio of 70:20:5:5. 0.6 Co 0.2 Mn 0.2 O2 powder), LGPS (Li 10 GeP2S 12 The powder, conductive additives (multi-walled carbon nanotubes with a length of 5μm and a diameter of 50nm and carbon black) and binder (polyvinylidene fluoride and polyethyleneimine in a mass ratio of 3:1) were mixed and made into a slurry using N,N-dimethylformamide as a solvent in an anhydrous environment. The slurry was then coated onto an aluminum alloy porous foil current collector (the foil has through holes with a diameter of 100 μm to enhance three-dimensional penetration). After drying, it was compacted under vacuum to obtain a composite positive electrode sheet with a thickness of 100μm. The composite positive electrode, LGPS electrolyte sheet and aluminum foil are stacked in sequence, pressed at room temperature under a pressure of 10MPa, and assembled with a stainless steel shell mold to obtain the battery.

[0063] Tests and Results

[0064] The battery was tested at different discharge rates at room temperature. Due to the high ionic conductivity of the LGPS solid electrolyte and the dual continuous electron and ion transport network provided by the composite cathode, the battery exhibited excellent rate performance. At 0.1C discharge, the specific capacity was 155 mAh / g; at 1C, it still reached 150 mAh / g (equivalent to 97% of the initial capacity); and at a high rate of 5C discharge, the capacity retention was approximately 85% (about 132 mAh / g), significantly better than the control cathode without LGPS and CNTs (the control only retained 50% capacity at 5C). This indicates that the composite electrode design greatly reduces the ion diffusion resistance and electron transport resistance within the electrode, enabling the battery to discharge efficiently even under high current.

[0065] Cyclic performance test

[0066] After 200 cycles at 0.5C, the capacity retention was 93%, while the control battery, due to severe interface and electrode polarization, dropped to 80% after only 100 cycles. Furthermore, SEM observation of the post-cycle composite cathode microstructure revealed tight contact between the active particles and the solid electrolyte, with no obvious interfacial cracks; in contrast, the control cathode showed signs of interfacial detachment around the particles. This demonstrates that the multi-component composite cathode not only improves instantaneous performance but also mitigates structural degradation during long-term cycling.

[0067] Example 4

[0068] LTO powder, Super P carbon black, and PVDF binder were mixed in N,N-dimethylformamide at a mass ratio of 90:5:5 to obtain the positive electrode slurry; LiMn2O4 powder, Super P carbon black, and PVDF binder were mixed in N,N-dimethylformamide at a mass ratio of 90:5:5 to obtain the negative electrode slurry. Three-dimensional nickel foam with a thickness of 1 mm, a porosity of 75%, and a pore size of 0.5 mm was used as the conductive framework material. The front and back sides of the nickel foam were impregnated into the positive and negative electrode slurries, respectively, in both directions. After impregnation, excess slurry filled the internal pore walls of the foam through capillary action. After drying, electrode frames with positive and negative active layers coated on both the inner and outer sides of the nickel foam were obtained (positive active material loading 10 mg / cm³). 2 Negative electrode 8 mg / cm 2 ).

[0069] Li with a particle size of 1 μm 1.5 Al 0.5 Ti 1.5 (PO4)3 ceramic powder was mixed with 5 wt% of ionic liquid EMIM-TFSI (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide) to prepare an ionic liquid modified solid electrolyte membrane, denoted as LATP-based solid electrolyte membrane. The LATP-based solid electrolyte membrane is sandwiched between the positive and negative active layers of the electrode frame, and pressure is applied until good contact is achieved. A nickel sheet is attached to the outside of the electrode frame to draw out the current, thus obtaining the structural battery.

[0070] Performance testing

[0071] This battery structure achieves ultra-low internal resistance and high power output because the positive and negative electrodes share the same foamed nickel framework. Pulse power testing at room temperature showed that after discharging at 10C for 10 seconds, the battery voltage dropped by only about 0.2 V, achieving a power density of 1000 W / kg. In contrast, a conventional layered battery composed of the same materials experienced a voltage drop of over 0.5V and a power density of less than 600 W / kg at 10C discharge. This embodiment of the battery retains 75% of its initial capacity even after discharging at 20C (completely discharged in 3 minutes), demonstrating superior high-rate performance. This is due to the three-dimensional framework extending the electron transport path from two dimensions to three dimensions, significantly reducing ohmic polarization.

[0072] Regarding cycle life, due to the extreme stability of the LTO negative electrode and the buffering of volumetric stress in the electrode material by the porous framework, the battery retains 90% of its capacity after 1000 charge-discharge cycles at 10C. Furthermore, no increase in internal resistance was observed after 500 cycles at 55°C with high current (5C), and the capacity retention rate remained greater than 90% after 200 cycles at 70°C with 20C. This demonstrates that the three-dimensional network facilitates rapid heat dissipation and mitigates interface degradation.

[0073] Mechanical properties

[0074] The nickel foam frame of the battery in this embodiment also provides excellent structural support. Under a vibration acceleration of 20g (simulating vehicle driving vibration), the internal electrode materials of the battery did not detach or pulverize, the structure remained intact, and the capacity did not change significantly before and after vibration. In contrast, the reference battery without frame support showed a significant performance decline after vibration under the same conditions (capacity decrease of 10%, internal active material deposition, and current collector breakage). It is evident that the porous 3D conductive network not only improves electrical performance but also greatly contributes to the battery's reliability and durability in real-world scenarios.

[0075] Example 5

[0076] Using LiFePO4 doped with 5wt% nano-graphite as the electrode active material, 5% PVDF binder, electrode active material and N,N-dimethylformamide were mixed according to the mass fraction of the electrode active material to obtain a positive electrode slurry. The obtained positive electrode slurry was coated on the inner side of carbon fiber fabric to form a positive electrode layer. 30 wt% ultrafine LLZO powder and 5 wt% ionic liquid plasticizer were added to an epoxy resin matrix, mixed and cast onto the surface of a lithium-intercalated carbon fiber anode, and cured in situ at 70°C to obtain an electrolyte-anode layer; the cured electrolyte-anode layer was stacked with a positive carbon fiber layer, and the positive electrode layer and electrolyte were tightly bonded by hot pressing, while the carbon fiber prepreg was cured to obtain a battery cell; A layer of γ-glycidyl etheroxypropyltrimethoxysilane coupling agent is impregnated on the surface of plasma-treated carbon fiber fabric. Then, two layers of carbon fiber fabric are taken and a battery cell is sandwiched in the middle to form a sandwich structure plate. The carbon fiber fabric serves as the upper and lower surfaces of the plate, acting as both the load-bearing layer and the current collector and load carrier of the battery.

[0077] Performance testing: Electrochemical performance: The fabricated structural solar panel was cut into 100 mm × 100 mm samples for testing. The areal specific capacity was measured to be 1.5 mAh / cm². 2 (Equivalent to a weight energy density of approximately 120 Wh / kg, calculated based on the weight of the entire sandwich panel). Due to the use of a solid electrolyte and carbon fiber anode, the battery exhibits no significant performance degradation during discharge at 80°C; at a low temperature of -20°C, it can output 70% of its nominal capacity, superior to conventional liquid lithium batteries (approximately 50%). Cycle life testing shows that after 500 cycles at a 0.5C charge-discharge rate, the capacity remains above 90%, demonstrating good stability.

[0078] Mechanical Properties: Mechanical properties of the entire solar panel structure were tested. A three-point bending test yielded a flexural modulus of approximately 40 GPa and an ultimate flexural strength of 320 MPa, close to the performance of a pure carbon fiber composite panel without integrated batteries (modulus 50 GPa, strength 350 MPa). This indicates that the structural load-bearing capacity only slightly decreases after the introduction of battery functionality. Vibration tests were conducted according to aerospace standard random vibration spectra (20–2000 Hz, RMS acceleration 5 g). After 2 hours of vibration, no delamination or damage was observed inside the battery, and no degradation in electrical performance was observed. Impact tests (15 g peak, 11 ms half-sine) also did not affect battery performance.

[0079] System-level effects: The structural battery panel was integrated into the drone's fuselage skin and combined with conventional lithium-ion battery modules to form a hybrid power system. Flight test results showed that the drone's overall weight was reduced by 12% and flight endurance increased by 15% after applying the structural battery. No abnormal temperature rise or voltage fluctuations were observed during operation of the structural battery panel in a low-pressure, high-altitude environment (-50℃) and under repeated thermal cycling (-50℃). It maintains stable operation even under conditions of +50℃, demonstrating excellent environmental adaptability and reliability.

[0080] As demonstrated by the above embodiments, this invention provides a composite-enhanced three-dimensional solid-state battery and its fabrication method. Example 5 proves the feasibility and superiority of the composite-enhanced three-dimensional solid-state battery of this invention in harsh application scenarios. Through the innovative synergy of multiple technologies such as material doping, interface polymers, composite electrodes, and three-dimensional frameworks, the battery provides high energy output while also possessing structural load-bearing capabilities, significantly improving the overall performance and efficiency of the system. Those skilled in the art can adjust the materials and structure according to different application requirements. This invention is of great significance for applications such as using thicker frames and high-capacity ternary cathodes for electric vehicle chassis structures, and using more flexible material systems for wearable devices.

[0081] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A composite-enhanced three-dimensional solid-state battery, characterized in that, It includes a composite positive electrode layer, a negative electrode layer, a solid electrolyte layer, and a three-dimensional conductive support framework; The three-dimensional conductive support frame penetrates both the composite positive electrode layer and the negative electrode layer; A functional polymer interface layer is provided between the composite positive electrode layer and the solid electrolyte layer, and a functional polymer interface layer is provided between the negative electrode layer and the solid electrolyte layer. The functional polymer interface layer is prepared from a polymer containing polar functional groups; The solid electrolyte layer is prepared from a solid electrolyte, which includes an oxide solid electrolyte, a sulfide solid electrolyte, or a polymer solid electrolyte. The solid electrolyte contains 0.1 to 5 mol% of doping elements based on the amount of substance of the solid electrolyte, and the doping elements include one or more of aluminum, gallium, yttrium and tantalum.

2. The composite-enhanced three-dimensional solid-state battery according to claim 1, characterized in that, The composite cathode layer is prepared from a multi-component cathode material; The raw material system of the multi-component positive electrode material includes electrode active material, conductive additive, solid electrolyte and polymer binder; The electrode active material of the composite positive electrode layer includes layered oxides, lithium-rich manganese-based materials, LiFePO4 powder, or spinel-type LiMn2O4 powder. The mass ratio of the electrode active material, conductive additive, solid electrolyte, and polymer binder is independently 0.65~0.8:0.02~0.05:0.1~0.18:0.08~0.

15.

3. The composite-enhanced three-dimensional solid-state battery according to claim 1, characterized in that, The negative electrode layer is prepared from a multi-component negative electrode material; The raw material system of the multi-component negative electrode material includes electrode active material, conductive additive, solid electrolyte and polymer binder; The electrode active material includes graphite, carbon fiber, silicon-based material, or tin-based material.

4. The composite-enhanced three-dimensional solid-state battery according to claim 1, characterized in that, The negative electrode layer can also be lithium foil, graphene-modified graphite, or lithium titanate.

5. A composite-enhanced three-dimensional solid-state battery according to claim 2 or 3, characterized in that, The conductive additives include carbon nanotubes, graphene, or conductive carbon black. The polymer binder includes polyvinylidene fluoride, polyether binders, or acrylonitrile copolymer binders.

6. A composite-enhanced three-dimensional solid-state battery according to claim 3, characterized in that, In the multi-component negative electrode material, the mass ratio of electrode active material, conductive additive, solid electrolyte and polymer binder is independently 0.65~0.8:0.02~0.05:0.1~0.18:0.08~0.

15.

7. A composite-enhanced three-dimensional solid-state battery according to claim 5, characterized in that, The electrode active material contains 0.1 to 5 mol% of doping elements, based on the amount of substance of the electrode active material. The doping elements include one or more of aluminum, magnesium, titanium, zirconium, and boron.

8. A composite-enhanced three-dimensional solid-state battery according to claim 1, characterized in that, The three-dimensional conductive support frame has a porous structure, and its materials include metal foam, metal fiber felt, three-dimensional printed metal skeleton, carbon foam, graphene skeleton or carbon fiber fabric. The porosity of the three-dimensional conductive support frame is 30~90%, and the volume conductivity is ≥10^4S / m.

9. A composite-enhanced three-dimensional solid-state battery according to claim 1, characterized in that, The composite-enhanced three-dimensional solid-state battery is fabricated into plate-shaped or shell-shaped structural components and used as the skin structure of drones or aircraft.

10. A method for preparing a composite-enhanced three-dimensional solid-state battery according to any one of claims 1 to 9, characterized in that, Includes the following steps: Step 1) Mix the electrode active material, conductive additive, polymer binder and solid electrolyte to obtain a positive electrode slurry. Coat the positive electrode slurry on one side of the three-dimensional conductive support frame and cure to form a composite positive electrode layer. Step 2) Prepare a solid electrolyte layer on the composite positive electrode layer by hot pressing or sintering. Step 3) A negative electrode layer is formed on the other side of the three-dimensional conductive support frame by means of melt infiltration, pressing and bonding, or coating and curing. Step 4) Introduce functional polymer interface materials at the interface of the composite positive electrode layer, negative electrode layer and solid electrolyte layer to form a functional polymer interface layer. Encapsulate the resulting battery assembly and perform hot-press curing treatment to obtain a composite reinforced three-dimensional solid battery.