Embedded structure battery based on honeycomb composite material and preparation method thereof

Abstract

The invention relates to a structural battery based on integration of a honeycomb composite material and an electrochemical energy storage unit. According to the structural battery, a force bearing function and an electric energy storage function are combined. According to the battery, a bionic honeycomb composite material is adopted as a matrix, and a lithium ion electrochemical unit is embedded into the matrix, so that the multifunctional structure battery with high mechanical strength and excellent electrochemical performance is formed. The honeycomb composite material is used as a carrier and an ion transmission channel of an electrode active material, and is also used as a bearing structure of a mechanical load. According to the design, the energy density, the safety and the cycle life of the battery are remarkably improved, and the battery is particularly suitable for the fields of electric automobiles, aerospace and the like with relatively high requirements on light weight and space utilization rate.

Description

An embedded structure battery based on honeycomb composite material and its fabrication method Technical Field

[0001] This invention relates to the field of lithium-ion batteries, and in particular to an embedded structure battery based on honeycomb composite materials and its preparation method. Background Technology

[0002] Traditional battery systems are typically installed as independent energy components within devices, providing only electrical energy without mechanical load-bearing capabilities. This increases the overall weight and space required by the system. With the growing demand for high energy density and lightweight designs in electric vehicles, drones, and portable electronic products, developing batteries that can both store energy and function as structural components has become an important research direction.

[0003] In current technologies, research on structural batteries largely focuses on combining battery materials with lightweight, high-strength materials such as carbon fiber. However, these technologies often face the challenge of balancing electrochemical and mechanical properties: enhancing mechanical properties may lead to a decrease in ionic conductivity; while prioritizing electrochemical performance may sacrifice structural integrity. Furthermore, volume changes during battery cycling (such as the volume expansion of silicon-based anodes) can easily cause electrode material pulverization and structural failure.

[0004] Honeycomb structures, as a classic lightweight and high-strength biomimetic structure, have been widely used in aerospace, construction, and other fields. Their key feature is achieving maximum space utilization and mechanical performance with minimal material usage. In recent years, research has attempted to incorporate honeycomb structures into battery design: for example, a team at Wenzhou University developed a honeycomb-shaped MoSe2 / rGO composite material for sodium-ion battery anodes, a structure that facilitates electrolyte penetration and mitigates volume changes. Harbin Institute of Technology developed a silicon-carbon composite material with a honeycomb structure to alleviate the volume expansion problem of silicon anodes in lithium-ion batteries. BYD's published "honeycomb" battery patent focuses on improving space utilization and structural strength through a hexagonal prism-shaped cell casing design.

[0005] Despite the progress made in these studies, the challenge of deeply integrating honeycomb composite materials with battery electrodes and electrolytes to form a truly "structural battery" while maintaining excellent electrochemical performance and mechanical strength remains.

[0006] Chinese invention patent application (publication number: CN120389178A) discloses a composite material structure battery based on a lattice sandwich layer and its preparation method. By embedding a lattice core into the electrochemical energy storage layer, the lightweight and high-strength properties of the lattice sandwich layer are fully utilized to provide effective internal support for the composite material structure battery based on the lattice sandwich layer. This invention utilizes the lattice sandwich layer structure to improve the load-bearing characteristics of the battery, but it cannot improve the structural load-bearing performance of the battery itself. Summary of the Invention

[0007] The present invention aims to overcome the shortcomings of the prior art and provide a structure battery based on honeycomb composite materials. Its objectives include: (1) integrating the energy storage function and structural load-bearing function of the battery to reduce the total weight of the system; (2) using the honeycomb structure to provide a support framework with high specific strength and high specific modulus, and providing an efficient channel for ion transport; (3) effectively suppressing the volume expansion of active materials (especially silicon-based materials) during the charging and discharging process and improving cycle stability; and (4) improving the thermal management performance of the battery and improving safety.

[0008] The technical solution of the present invention is to provide a structured battery based on a honeycomb composite material, comprising a current collector, an electrode composite material layer, and an electrolyte / separator layer stacked sequentially; the electrode composite material layer comprises a composite material matrix with a three-dimensional honeycomb structure and an electrode active material uniformly embedded in the matrix; the honeycomb structure serves as a transport channel for ions and electrons, and also as a load-bearing structure.

[0009] Furthermore, the honeycomb composite matrix is ​​composed of at least one of carbon materials, polymers, or metal alloys; the average pore size of its honeycomb structure is 40 nm to 600 nm.

[0010] Furthermore, when the electrode active material is a positive electrode active material, it is a layered positive electrode material containing Li or Na with a honeycomb pore structure in the core, a phosphate positive electrode material, a spinel type positive electrode material, etc.; when the electrode active material is a negative electrode active material, it is a silicon-carbon composite material, a graphene-based composite material, a composite lithium metal, and other carbon-based negative electrode materials.

[0011] Furthermore, the layered cathode material precursor with a honeycomb porous structure in the core is prepared by co-precipitation, and its growth coefficient K is controlled in the range of 0.01 to 0.025.

[0012] Furthermore, the feature is that it also includes a reinforcing fiber layer and reinforcing ribs; the reinforcing ribs penetrate the electrode layer vertically, forming a three-dimensional cross-linked reinforcing network.

[0013] Another technical solution of the present invention provides a method for preparing the above-mentioned structured battery, comprising the following steps: preparing a composite material matrix with a three-dimensional honeycomb structure; embedding or loading electrode active materials into the composite material matrix to form an electrode composite material; and integrating the electrode composite material with an electrolyte / separator and a current collector.

[0014] Furthermore, the integrated assembly adopts a winding-stacked composite process or a three-dimensional reinforcing rib through-through reinforcement process.

[0015] The beneficial effects of the present invention: Compared with the prior art, the present invention has the following significant advantages: (1) Functional integration: The honeycomb composite material serves as both a carrier of the electrode active material and a mechanical load-bearing structure, achieving a high degree of integration of energy storage and structural functions, greatly improving the space utilization and energy efficiency of the equipment. (2) Excellent electrochemical performance: The honeycomb porous structure is conducive to electrolyte wetting, expands the contact area between the material and the electrolyte, and shortens the Li + The diffusion path improves output performance and rate characteristics. (3) Excellent mechanical properties and long life: The honeycomb structure can effectively absorb and disperse stress, suppress the damage caused by the volume expansion of active materials (especially silicon) during cycling, prevent electrode structure collapse failure, and thus significantly extend the cycle life of the battery. Combined with the three-dimensional reinforced network design, the interlayer shear strength and interface bonding force of the overall structure are strengthened. (4) Enhanced safety: The honeycomb structure helps the uniform distribution and diffusion of heat, avoids the generation of local hot spots, and combined with the possible application of solid electrolyte, improves the thermal safety performance of the battery. Attached Figure Description

[0016] The invention will be further described below with reference to the accompanying drawings: Figure 1 is a schematic diagram of the battery structure of the present invention.

[0017] Figure 2 is a schematic diagram of the microstructure of the honeycomb composite electrode.

[0018] Figure 3 shows the cycle performance of a pouch-type lithium-ion battery. Detailed Implementation

[0020] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a further detailed account of the embedded structure battery based on honeycomb composite materials and its fabrication method proposed in this invention. The advantages and features of this invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise ratios, and are only used to facilitate and clarify the illustration of the embodiments of this invention.

[0021] This invention provides an embedded structure battery based on honeycomb composite materials, comprising: a positive electrode current collector, a positive electrode composite material layer, an electrolyte / separator layer, a negative electrode composite material layer, and a negative electrode current collector stacked sequentially. The key feature is that the positive electrode composite material layer and / or the negative electrode composite material layer utilize a three-dimensional honeycomb structure composite material as the framework and active material carrier.

[0022] The honeycomb composite skeleton is formed by template method or sintering process of reduced graphene oxide, carbon nanotubes or polymer (such as polyacrylonitrile) to form a matrix with regular honeycomb pores. The matrix also serves as a conductive network and mechanical support structure.

[0023] The active materials can be selected from various types, including high-nickel materials, lithium iron phosphate, spinel-type positive electrode materials, or lithium-rich manganese-based materials for the positive electrode; and silicon-based materials, hard carbon, or composite lithium metal for the negative electrode. The active materials are uniformly embedded in the walls of the honeycomb pores or fill the pores in the form of nanoparticles.

[0024] The interface layer can introduce a chemical bonding interface (such as CO-Si, COM, etc.) between the honeycomb composite material and the active material, thereby enhancing interface stability and promoting charge transport.

[0025] The reinforcing layer may include a reinforcing fiber layer (such as carbon fiber or glass fiber) and is formed by vertical "reinforcing ribs" penetrating the battery layer to form a three-dimensional cross-linked reinforcing network, which significantly improves the interlayer shear strength and interfacial bonding force, and realizes the reconstruction of the mechanical transmission path and uniform load distribution.

[0026] The present invention also provides a method for preparing an embedded structure battery based on the above-mentioned honeycomb composite material, comprising: step 1, the preparation of the honeycomb carbon matrix, wherein a high molecular organic compound (such as polyvinylpyrrolidone) and a small molecular organic compound (such as melamine) are mixed and ground at a mass ratio of 1:(2~3), and sintered at 800-900℃ for 1.5-2 hours under an inert atmosphere to form a porous carbon matrix.

[0027] Step 2, the loading and composite of the active material: For the positive electrode, a ternary precursor with a honeycomb core structure can be prepared using a co-precipitation method. By controlling the pH value, atmosphere, and growth coefficient K (0.01~0.025) during the nucleation and growth stages, the precursor core forms a honeycomb porous structure, which is then sintered with lithium salt to obtain the positive electrode material. For the negative electrode, the above carbon matrix is ​​mixed with silane reagent and phytic acid solution in a solvent, stirred, and allowed to stand to form a gel. Finally, it is sintered at 800-900℃ for 2 hours to obtain SiO with a honeycomb structure. x / C composite material.

[0028] Step 3, the electrode integration and battery assembly involves integrating the prepared honeycomb composite positive and negative electrode materials with a solid electrolyte (or a porous membrane impregnated with electrolyte) through a hot-pressing composite method. Based on the stack-folding process concept, the positive and negative electrode sheets and the separator are alternately stacked or subjected to a winding-stacking composite operation, and finally packaged into shape. Example

[0029] A mixed salt solution of Ni, Co, and Mn (total metal ion concentration 2.0 mol / L), sodium hydroxide solution (precipitant), and ammonia (complexing agent) were introduced into a reactor. The reaction was carried out for 15 minutes under an atmosphere with an oxygen concentration >10%, and the pH was controlled at 12.0. The reaction atmosphere was then switched to nitrogen (oxygen concentration <5%), and the pH was adjusted to 10.5. The growth coefficient K was controlled at 0.015, and the reaction continued until the desired particle size was achieved. After the reaction was completed, the sample was filtered, washed, and dried to obtain Ni with a honeycomb core structure. 0.6 Co 0.2 Mn 0.2 (OH)2 precursor. The precursor was mixed with lithium carbonate in a stoichiometric ratio and sintered at high temperature in an oxygen atmosphere to obtain a ternary cathode material.

[0030] Polyvinylpyrrolidone (PVP) and urea were weighed in a mass ratio of 1:2, mixed, and ground until homogeneous. The mixed powder was sintered at 850°C for 1.5 hours under an argon atmosphere to obtain a porous carbon matrix. 1 g of this carbon matrix was weighed and dissolved in 30 ml of N,N-dimethylformamide (DMF) solvent. 0.5 ml of phytic acid solution and 2 ml of 3-aminopropyltriethoxysilane were added with stirring, and the mixture was allowed to stand for 10 hours after stirring to obtain a gel. The gel was sintered at 850°C for 2 hours under an argon atmosphere, and after natural cooling, SiO₂ with a honeycomb structure was obtained. x / C composite material.

[0031] The aforementioned silicon-carbon composite material, conductive agent (Super P), and binder (polyvinylidene fluoride, PVDF) were mixed uniformly in N-methylpyrrolidone (NMP) at a mass ratio of 90:5:5, coated onto a carbon fiber current collector, and dried to obtain a negative electrode sheet. The aforementioned ternary positive electrode material, conductive agent, and binder were mixed uniformly in NMP at a mass ratio of 96:2:2, coated onto an aluminum foil current collector, and dried to obtain a positive electrode sheet. A microporous polyethylene (PE) separator was used, impregnated with an EC / DEC / FEC electrolyte containing 1M LiPF6. Based on a three-dimensional reinforcement structure design, carbon fiber reinforcement layers, positive electrode sheets, separators, negative electrode sheets, and carbon fiber reinforcement layers were sequentially stacked. High-strength carbon fibers were used as "reinforcing ribs" vertically penetrating these layers to form a three-dimensional anchoring system. Finally, a roll-up process was used for integration, and the entire structure was hot-pressed and encapsulated in an aluminum-plastic composite film to form a soft-pack lithium-ion battery. After formation and capacity assessment, the full cell is cycled at a rate of 0.5C, and the capacity retention rate exceeds 78% after 1000 cycles.

[0032] Compression tests on the battery module showed that its compressive strength was significantly higher than that of traditional battery packs, demonstrating its excellent load-bearing capacity. Example

[0033] PVP was dispersed in ethylene glycol to obtain a homogeneous first mixture. Sodium, vanadium, and phosphorus sources were added to the first mixture, and the mixture was stirred and reacted at 15-30°C for 8-12 hours. The reacted mixture was then transferred to a high-pressure reactor and heated at 160-200°C for 14-18 hours to obtain a precursor. The precursor was then held at 500-700°C in air for 1-3 hours to completely remove the PVP template, yielding an intermediate product. The intermediate product was sintered at 900-1000°C in argon atmosphere for 10-14 hours, and after natural cooling, a honeycomb structure Na3V2(PO4)3 cathode material was obtained.

[0034] Graphene oxide was added to deionized water and ultrasonically dispersed for 30 minutes. Sodium molybdate was added to the dispersion and stirred until homogeneous. Selenide solution was slowly added and stirred until homogeneous again. The mixture was then transferred to a high-pressure reactor and reacted at 200°C for 12 hours. After cooling, the precipitate was collected by centrifugation, washed three times with ethanol and deionized water, and freeze-dried for 12 hours to obtain a honeycomb structure MoSe2 / rGO composite anode material.

[0035] The above-mentioned composite negative electrode material, conductive agent (Super P), and binder (polyvinylidene fluoride, PVDF) were mixed uniformly in N-methylpyrrolidone (NMP) at a mass ratio of 80:10:10, coated onto a carbon fiber current collector, and dried to obtain a negative electrode sheet. The above-mentioned Na3V2(PO4)3 positive electrode material, conductive agent, and binder were mixed uniformly in NMP at a mass ratio of 95:3:2, coated onto an aluminum foil current collector, and dried to obtain a positive electrode sheet. A microporous polyethylene (PE) separator was used, impregnated with an EC / EMC / VC electrolyte containing 1M NaPF6. Based on a honeycomb reinforced structure design, a roll-up process was used for integration, and the entire structure was hot-pressed and encapsulated in an aluminum-plastic composite film to form a soft-pack sodium-ion battery.

[0036] The embedded structure battery based on honeycomb composite material and its preparation method provided by this invention greatly improves the space utilization and energy efficiency of the device, enhances the output performance and rate characteristics, significantly extends the cycle life of the battery, and improves the thermal safety performance of the battery.

[0037] The contents not described in detail in this specification are prior art known to those skilled in the art. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. An embedded structure battery based on honeycomb composite material, characterized in that, It consists of a positive electrode current collector, a positive electrode composite material layer, an electrolyte / separator layer, a negative electrode composite material layer, and a negative electrode current collector stacked sequentially from top to bottom; at least one of the positive electrode composite material layer and the negative electrode composite material layer contains a composite material matrix with a three-dimensional honeycomb structure and an electrode active material uniformly embedded in the matrix; the honeycomb structure serves as a transport channel for ions and electrons, and also as a load-bearing structure.

2. The embedded structure battery based on honeycomb composite material as described in claim 1, characterized in that, The composite material matrix with a three-dimensional honeycomb structure is composed of at least one of carbon materials, polymers and metal alloys. Its honeycomb structure has an average pore size of 40nm to 600nm.

3. The embedded structure battery based on honeycomb composite material as described in claim 1, characterized in that, The cathode composite material layer adopts a layered cathode material containing Li or Na, a phosphate cathode material, or a spinel-type cathode material with a honeycomb pore structure in the core.

4. The embedded structure battery based on honeycomb composite material as described in claim 1, characterized in that, The negative electrode composite material layer is made of graphite-based negative electrode material, silicon-carbon composite material, graphene-based composite material, or composite lithium metal.

5. The embedded structure battery based on honeycomb composite material as described in claim 3, characterized in that, The precursor of the Li or Na-containing layered cathode material with a honeycomb pore structure in the core is prepared by co-precipitation, and its growth coefficient K is controlled in the range of 0.01 to 0.

025.

6. The embedded structure battery based on honeycomb composite material as described in claim 1, characterized in that, In the positive electrode composite material layer and the negative electrode composite material layer, the active material is uniformly embedded in the wall of the honeycomb pores or filled in the honeycomb pores in the form of nanoparticles.

7. The embedded structure battery based on honeycomb composite material as described in claim 1, characterized in that, It also includes a reinforcing fiber layer and reinforcing ribs; the reinforcing ribs penetrate vertically through the battery layer to form a three-dimensional cross-linked reinforcing network.

8. A method for preparing an embedded structure battery based on a honeycomb composite material as described in any one of claims 1 to 6, characterized in that, The process includes the following steps: Step S1: Preparing a composite matrix with a three-dimensional honeycomb structure: Mixing and grinding high-molecular organic matter and low-molecular organic matter at a mass ratio of 1:(2~3), and sintering at 800-900℃ for 1.5~2 hours under an inert atmosphere to form a porous carbon matrix; Step S2: Embedding or loading electrode active materials into the composite matrix to form an electrode composite material: For the positive electrode composite layer, a ternary precursor with a honeycomb structure core is prepared by co-precipitation; by controlling the pH value, atmosphere, and growth coefficient K during the nucleation and growth stages, the precursor core forms a honeycomb pore structure, and then sintering it with lithium salt to obtain the positive electrode material; For the negative electrode composite layer, mixing the carbon matrix with silane reagent and phytic acid solution in a solvent, stirring, and allowing it to stand to form a gel, and finally sintering at 800-900℃ for 2 hours to obtain SiO with a honeycomb structure. x / C composite material; Step S3, integrate the electrode composite material with the electrolyte / diaphragm and current collector: integrate the prepared honeycomb composite positive and negative electrode materials with the solid electrolyte or the porous diaphragm impregnated with electrolyte by hot pressing composite; adopt the roll-and-stack process to alternately stack the honeycomb composite positive and negative electrode materials with the solid electrolyte or the porous diaphragm impregnated with electrolyte or perform a roll-and-stack composite operation, and finally encapsulate and form.

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