Aluminum ion battery based on bionic cnt / al composite metal negative electrode

Abstract

This invention belongs to the field of aluminum-ion battery technology, specifically relating to an aluminum-ion battery based on a biomimetic CNT / Al composite metal anode. It comprises a positive electrode, a non-aqueous aluminum salt-based ionic liquid electrolyte, a separator, and a biomimetic CNT / Al composite metal anode. The biomimetic CNT / Al composite metal anode consists of an aluminum substrate and a three-dimensional continuous electron permeation network formed within the aluminum substrate. The aluminum substrate is a micro / nano-scale aluminum sheet, and the three-dimensional continuous electron permeation network is formed by carboxylated multi-walled carbon nanotubes. The three-dimensional continuous electron permeation network extends to the surface of the biomimetic CNT / Al composite metal anode. Compared with existing technologies, this invention solves the problem that existing technologies cannot simultaneously address the issues of ion mass transfer kinetics and interfacial mechanical stability during long-term cycling. This solution achieves long-term stable cycling of the aluminum-ion battery under harsh conditions by constructing a CNT / Al anode with a carbon nanotube (CNT)-like neural network structure.

Description

Technical Field

[0001] This invention belongs to the field of aluminum-ion battery technology, specifically relating to an aluminum-ion battery based on a biomimetic CNT / Al composite metal anode. Background Technology

[0002] Aluminum-ion batteries (AIBs) benefit from the abundance and low cost of aluminum resources, and aluminum as the negative electrode possesses an extremely high theoretical volumetric capacity (8046 mAh·cm³). -3 ) and specific capacity (2981 mAh·g) -1 This technology has become a highly promising post-lithium-ion battery technology in the field of large-scale energy storage, with broad application prospects in areas such as grid energy storage and portable electronic devices.

[0003] However, the practical application of aluminum-based metal anodes faces many key technical bottlenecks. Their uncontrollable electrochemical behavior and severe structural degradation are the core obstacles restricting the industrialization of this technology. Specifically, they are manifested in the following aspects: (1) Surface passivation and impeded interfacial mass transfer: A dense aluminum oxide (Al2O3) passivation layer naturally exists on the surface of commercial planar aluminum foil. This passivation layer severely hinders the effective conduction and diffusion of active ions, resulting in slow electrochemical kinetics. At the same time, the intrinsic defects of the aluminum oxide layer lead to extremely uneven spatial distribution of surface charge, which destroys the uniformity of ion flux and thus forms preferential nucleation sites locally, inevitably inducing the growth of aluminum dendrites. (2) Dendrite growth and accumulation of "dead aluminum": Disordered aluminum deposition / stripping behavior leads to severe dendrite growth and propagation. As the cycle progresses, the electron permeation network composed of the loose aluminum deposition layer and irregular dendrites is inherently very fragile. Under polarization, it is very easy to break and collapse, causing some active aluminum to detach from the conductive network and form "dead aluminum" that cannot participate in the reaction, resulting in a decrease in battery coulombic efficiency and rapid capacity decay. (3) Weak interfacial adhesion and mechanical degradation: The interfacial adhesion between the newly deposited aluminum layer and the bottom aluminum substrate is weak. During long-term cycling, with the periodic changes in volume, the negative electrode structure is prone to mechanical degradation such as pulverization and peeling, which further aggravates the overall failure of the negative electrode structure.

[0004] To address these issues, researchers have attempted to improve the electrochemical performance of aluminum metal electrodes through strategies such as alloying to enhance aluminum affinity and induce uniform aluminum deposition, or by constructing artificial solid electrolyte interfaces (SEIs). For example, CN108615933A discloses an aluminum-ion battery based on a novel cathode material and its preparation method. However, these conventional improvement methods have significant limitations in practical applications: Firstly, high-affinity substrates often exhibit spatial inhomogeneities in their intrinsic electric fields, making it impossible to achieve strictly uniform aluminum deposition simultaneously at both macroscopic and microscopic scales. More problematic is that once aluminum initially nucleates, subsequent deposition processes are primarily controlled by dominant Al-Al interactions, causing the newly deposited layer to gradually lose affinity with the underlying substrate, inevitably reverting to a random growth pattern and inducing dendrite formation. Secondly, while constructing an artificial SEI layer can regulate the initial interfacial electric field distribution to some extent, the Young's modulus of aluminum is much higher than that of alkali metals such as lithium and sodium. During charge-discharge cycles and accompanying volume changes, the flexible or brittle artificial SEI structure is highly susceptible to fracture and mechanical failure. Therefore, such surface modification strategies are difficult to apply to high areal capacities (> 3 mAh·cm³) that have practical application value. -2 It maintains long-term cycle stability.

[0005] In summary, existing aluminum metal anodes suffer from inherent problems such as uneven charge distribution, easy dendrite growth, and poor structural stability. Existing improvement strategies all have inherent defects that are difficult to overcome, failing to simultaneously address ion mass transfer kinetics and interfacial mechanical stability during long-term cycling. Therefore, there is an urgent need in this field to develop a novel aluminum-based composite electrode structure and its fabrication method that can achieve uniform interfacial charge distribution, possess interfacial self-adaptation capabilities, and significantly improve the mechanical stability of the anode. This is also a key requirement for advancing the practical application of advanced aluminum-ion batteries. Summary of the Invention

[0006] The purpose of this invention is to provide an aluminum-ion battery based on a biomimetic CNT / Al composite metal anode to solve at least one of the aforementioned problems, thereby addressing the issue that existing technologies cannot simultaneously achieve optimal ion mass transfer kinetics and interfacial mechanical stability during long-cycle operation. This solution overcomes the technical bottlenecks of passivation, dendrite growth, structural degradation, and poor cycle stability in aluminum-based composite metal anodes by constructing a CNT / Al anode with a carbon nanotube (CNT)-like neural network structure, achieving long-cycle stable operation of the aluminum-ion battery under harsh conditions.

[0007] The objective of this invention is achieved through the following technical solution: An aluminum-ion battery based on a biomimetic CNT / Al composite metal anode consists of a positive electrode, a non-aqueous aluminum salt-based ionic liquid electrolyte, a separator, and a biomimetic CNT / Al composite metal anode. The biomimetic CNT / Al composite metal anode consists of an aluminum matrix and a three-dimensional continuous electron permeation network formed inside the aluminum matrix. The aluminum matrix is ​​a micro-nano-scale aluminum sheet, and the three-dimensional continuous electron permeation network (a three-dimensional continuous carbon nanotube-like neural network) is formed by carboxylated multi-walled carbon nanotubes. The three-dimensional continuous electron permeation network extends to the surface of the biomimetic CNT / Al composite metal anode.

[0008] Preferably, the thickness of the biomimetic CNT / Al composite metal anode is 10~200 μm.

[0009] Preferably, the thickness of the biomimetic CNT / Al composite metal anode is 100 ± 5 μm.

[0010] Preferably, in the biomimetic CNT / Al composite metal anode, the mass ratio of carbon nanotubes to aluminum matrix is ​​0.5:99.5~2:98.

[0011] Preferably, the biomimetic CNT / Al composite metal anode is prepared by the following method: S1: Ball milling is performed on spherical aluminum powder to cause plastic deformation and transform it into two-dimensional micro / nano aluminum sheets; the surface of the two-dimensional micro / nano aluminum sheets is modified with polyvinyl alcohol to obtain a dispersion of two-dimensional micro / nano aluminum sheets. S2: Carboxylated multi-walled carbon nanotubes are ultrasonically dispersed in water to prepare an aqueous suspension; the aqueous suspension is added to the dispersion of two-dimensional micro / nano aluminum sheets obtained in step S1, and then separated to obtain CNT / Al composite powder; S3: The CNT / Al composite powder obtained in step S2 is densified to obtain CNT / Al composite metal foil; S4: The CNT / Al composite metal foil obtained in step S3 is finely processed to obtain a biomimetic CNT / Al composite metal anode.

[0012] Preferably, in step S1, the ball milling speed is 400~450 r / min, the ball milling time is 1~2 h; the thickness of the two-dimensional micro / nano aluminum sheet is 200~800 nm; and the polyvinyl alcohol contains 1700~1800 repeating units.

[0013] Preferably, in step S2, the diameter of the carboxylated multi-walled carbon nanotubes is 30~50 nm; and the ultrasonic dispersion time is 2 h.

[0014] Preferably, in step S3, the densification process includes impurity removal, cold pressing, sintering, and hot extrusion; The impurity removal process is: heat treatment; The cold pressing is performed at a pressure of 500 MPa. The sintering process is as follows: sintering at 500~600 ℃ for 1~3 h under argon protection; The hot extrusion is a rolling process at 500 °C.

[0015] Preferably, in step S4, the finishing process includes surface treatment, punching, cleaning, and drying.

[0016] Preferably, the positive electrode is one of artificial graphite, natural graphite, activated carbon, transition metal sulfides, and conductive polymers; The diaphragm is a glass fiber diaphragm; The non-aqueous aluminum-based ionic liquid electrolyte is a mixture of AlCl3 and 1-ethyl-3-methylimidazolium chloride.

[0017] The working principle of this invention is as follows: This invention is inspired by the highly efficient survival system of the ancient multicellular organism, the sea anemone. The diffuse neural network distributed on the anemone's tentacles can highly synchronously sense and integrate external environmental stimuli and respond extremely rapidly. Inspired by this biological signal transmission and regulation mechanism, this invention creatively proposes to use powder metallurgy to uniformly implant aluminophilic carbon nanotubes (CNTs: carboxylated multi-walled carbon nanotubes) into an aluminum matrix, constructing a three-dimensional "diffuse neural network" electrode structure with nerve conduction-like functions.

[0018] In this structure, the CNT network not only serves as a highly efficient electron / ion transport channel, effectively reducing interfacial polarization and improving charge conversion efficiency, thus enhancing overall electrochemical kinetic performance; more importantly, given the low density, high Young's modulus, and ultra-high mechanical strength of CNTs, they are deeply anchored in the aluminum matrix as a biomimetic mechanical reinforcement phase, endowing the electrode with excellent resistance to deformation and fracture. This biomimetic design achieves a deep integration of mass transfer kinetics and interfacial mechanical toughness, effectively coordinating and ensuring the structural integrity and excellent performance of the aluminum anode under long-term cycling.

[0019] Specifically: (1) By using the CNTs-type neural permeation network as a continuous and efficient electrical signal transmission channel, the mass transfer barrier caused by the spontaneously formed alumina passivation layer can be effectively destroyed, and the uniform distribution of interface charge can be achieved at both the macroscopic and microscopic scales, thereby fundamentally suppressing random aluminum nucleation and dendrite growth.

[0020] (2) By exposing CNTs-like neural networks in situ during charge-discharge cycles, a dynamic and adaptive CNT-regulated interphase is constructed. This dynamic interface can effectively overcome the defects of traditional static artificial coatings that are prone to cracking and failure under volume expansion, and achieve long-term adaptive optimization of the interfacial electric field.

[0021] (3) The excellent mechanical properties of CNTs provide strong internal support and anchoring for the fragile aluminum deposition layer. Through this biomimetic mechanical reinforcement mechanism, the deposition layer peeling, structural collapse, pulverization and "dead aluminum" generation are prevented during long-term cycling, ensuring that the structure remains extremely stable even at high capacity.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1. Constructing a biomimetic topological network to intrinsically suppress dendrite growth: Using carbon nanotubes (CNTs)-like neural networks to achieve rapid homogenization of interfacial charge and ion flux, thereby significantly reducing the overpotential of CNT / Al composite metal anode nucleation.

[0023] 2. Dynamic adaptive regulation of the interface, achieving a breakthrough in ultra-long cycle life: In-situ exposed CNTs during cycling construct a dynamically regulated interface phase, effectively cutting off the "dead aluminum" formation path. Symmetric cells achieve a cycle life of 1 mA·cm⁻¹. -2 0.5 mAh·cm -2 It can be stably cycled for over 1500 h, far exceeding the cycle performance of commercial pure aluminum electrodes (200 h); more significantly, at 5 mA·cm -2 Under harsh high-rate (high-current-density) conditions, the biomimetic negative electrode of this invention can still cycle stably for 650 hours, while traditional commercial aluminum foil symmetric cells fail within 30 hours due to dendrite growth under the same harsh conditions. This comparative data fully demonstrates the superior anti-dendrite ability and structural robustness of the electrode of this invention under harsh high-rate conditions. 3. Mechano-electrochemical synergistic enhancement significantly improves structural robustness: The CNT network has both high conductivity and high mechanical strength, which greatly improves the mechanical strength of the deposited aluminum layer and the interfacial anchoring force with the underlying aluminum substrate, effectively solving the mechanical degradation problems such as collapse, pulverization and peeling failure of the electrode structure in long-term cycling.

[0024] 4. Large-scale metallurgical process with great potential for low-cost commercialization: The preparation adopts a sheet powder metallurgy method, which is simple and controllable. The aluminum powder and carbon nanotubes used are industrial raw materials, which do not require complex equipment and can achieve large-scale and industrialized preparation, meeting the production needs of the aluminum-ion battery industry. Attached Figure Description

[0025] Figure 1 The diagram shows the structure of the biomimetic CNT / Al negative electrode of the present invention (a) and the scanning electron microscope image of Example 1 (b).

[0026] Figure 2 The biomimetic CNT / Al anode of Example 1 and the commercial pure aluminum anode of Comparative Example 1 were compared at 1 mA·cm⁻¹. -2 Comparison curves of nucleation overpotential under certain conditions.

[0027] Figure 3 The biomimetic CNT / Al anode of Example 1 and the commercial pure aluminum anode of Comparative Example 1 were compared at 1 mA·cm⁻¹. -2 0.5 mAh·cm -2 Constant current charge-discharge curves under certain conditions.

[0028] Figure 4 The biomimetic CNT / Al anode of Example 1 and the commercial pure aluminum anode of Comparative Example 1 were compared at 5 mA·cm⁻¹. -2 0.5 mAh·cm -2 Constant current charge-discharge curves under certain conditions.

[0029] Figure 5 The biomimetic CNT / Al anode of Example 1 and the commercial pure aluminum anode of Comparative Example 1 were compared at 1 mA·cm⁻¹. -2 0.5 mAh·cm -2 Nanoindentation load-displacement curves after 100 h of cycling under the specified conditions. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0031] Unless otherwise specified, the reagents used may be commercially available products, the methods used may be those known in the art, and any other matters not covered herein may be handled using existing technology.

[0032] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an aluminum-ion battery based on a biomimetic CNT / Al composite metal anode. This invention draws inspiration from the biomimetic three-dimensional continuous electron permeation network of sea anemone tentacles for a highly sensitive diffuse neural network with efficient electrical signal transmission, and combines this with the superior mechanical toughness and structural robustness it provides. A CNT / Al anode with a carbon nanotube (CNT)-like neural network structure is constructed, solving the technical bottlenecks of passivation, dendrite growth, structural degradation, and poor cycle stability in aluminum-based composite metal anodes. Furthermore, the application of this biomimetic anode in aluminum-ion batteries enables long-term stable cycling under harsh conditions, promoting the practical development of aluminum-ion batteries.

[0033] This aluminum-ion battery includes a positive electrode, a non-aqueous aluminum salt-based ionic liquid electrolyte, a separator, and a biomimetic CNT / Al composite metal negative electrode; among which... (1) The biomimetic CNT / Al composite metal anode contains an aluminum matrix and carbon nanotubes, in which carbon nanotubes form a three-dimensional continuous electron percolation network in the aluminum matrix; (2) In the initial state, the carbon nanotubes in the biomimetic CNT / Al composite metal anode are uniformly dispersed in the aluminum matrix, and the electron permeation network extends to the surface of the composite metal anode to disrupt the insulation continuity of the intrinsic alumina passivation layer on the surface of the aluminum matrix. (3) The biomimetic CNT / Al composite metal anode has dynamic adaptive structural characteristics: during charge and discharge cycles, the carbon nanotubes inside can be exposed in situ on the anode surface, thereby forming an interface regulation layer rich in carbon nanotubes.

[0034] Furthermore, the thickness of the biomimetic CNT / Al composite metal anode is 10~200 µm.

[0035] Furthermore, the thickness of the biomimetic CNT / Al composite metal anode is 100 ± 5 µm.

[0036] Furthermore, the mass ratio of carbon nanotubes to aluminum matrix is ​​0.5:99.5 to 2:98.

[0037] Furthermore, the positive electrode is one of artificial graphite, natural graphite, activated carbon, transition metal sulfides, or conductive polymers; the diaphragm is a glass fiber diaphragm; and the non-aqueous aluminum salt-based ionic liquid electrolyte is a mixture of AlCl3 and 1-ethyl-3-methylimidazolium chloride.

[0038] Furthermore, the preparation method of the biomimetic CNT / Al composite metal anode includes the following steps: S1. Morphology control and preparation of two-dimensional micro / nano aluminum sheets: Spherical aluminum powder with a purity >99.5% and an initial particle size of about 10 µm is ball-milled at a speed of 400~450 r / min (preferably 423 r / min) for 1~2 h at room temperature to cause plastic deformation and transform it into two-dimensional micro / nano aluminum sheets with a thickness of about 200~800 nm.

[0039] This morphology control step eliminates the curvature effect of spherical particles, improves the geometric fit between the aluminum matrix and one-dimensional CNTs, and provides a flat and wide surface that can accommodate long-sized CNTs without severe bending.

[0040] S2. Synthesis of carbon nanotube-coated two-dimensional micro / nano aluminum sheet composite powder: S2-1. Carboxylated multi-walled carbon nanotubes (MWCNTs) with a diameter of approximately 30-50 nm and a length of approximately 2 µm were ultrasonically dispersed for 2 h to prepare an aqueous suspension; S2-2. The two-dimensional micro / nano aluminum sheet obtained in step S1 is surface modified with polyvinyl alcohol (PVA) containing 1700~1800 repeating units to obtain a dispersion containing the two-dimensional micro / nano aluminum sheet. S2-3. Under continuous stirring, the aqueous dispersion of S2-1 was added dropwise to the modified two-dimensional micro / nano aluminum sheet dispersion of S2-2 until the system color completely transitioned from black to transparent; then the product was collected by vacuum filtration and washed with deionized water to obtain CNT / Al composite powder.

[0041] The modified two-dimensional micro / nano aluminum sheet forms strong hydrogen bonds between the hydroxyl groups (-OH) in the PVA coating and the carboxyl groups (-COOH) on the functionalized CNTs. This interfacial hydrogen bonding, which enables self-assembly through hydrogen bonding, can uniformly and firmly anchor the CNTs to the surface of the two-dimensional micro / nano aluminum sheet, effectively preventing them from falling off during subsequent rinsing and drying processes.

[0042] S3. Continuous densification treatment of CNT / Al composite powder: S3-1. Impurity removal and cold pressing: The obtained CNT / Al composite powder was heat-treated at 500 °C for 2 h under argon gas protection to completely remove organic matter such as PVA; then it was cold-pressed at 500 MPa to form a dense block. S3-2. Sintering stabilization: The dense bulk material is sintered at 500~600 ℃ for 1~3 h under argon protection to ensure the stability of the composite structure; S3-3. Hot extrusion into foil: The CNT / Al composite metal foil with a certain thickness (e.g., about 150 µm) is prepared by rolling at 500 °C through a roll-to-roll hot extrusion process to achieve complete densification.

[0043] S4. Finishing of the biomimetic CNT / Al composite metal anode: Before assembling the battery, the CNT / Al composite metal foil is subjected to surface pretreatment such as mechanical polishing; then it is punched into a circular electrode with a diameter of 10 mm, and after cleaning and drying, the final biomimetic CNT / Al composite metal anode is obtained for the assembly of aluminum-ion batteries.

[0044] Inside the fabricated biomimetic CNT / Al composite metal anode, two-dimensional micro / nano aluminum sheets and carbon nanotubes overlap to form a composite network with a mechanically interlocked structure, such as... Figure 1 As shown, where, Figure 1The alumina layer mentioned is a natural intrinsic alumina passivation layer spontaneously formed on the surface of the CNT / Al composite metal anode during the cleaning and drying process in air. This network not only serves as a highly efficient electrical signal transmission channel, breaking through the mass transfer barrier of the interfacial alumina and achieving uniform charge distribution to fundamentally suppress random nucleation and dendrite growth; it also constructs a dynamically adaptively controlled interfacial phase through in-situ exposure during cycling, achieving long-term optimization of the interfacial electric field. Simultaneously, its excellent mechanical properties provide strong internal support and interfacial anchoring for the deposited layer, effectively preventing structural collapse, pulverization, and the formation of "dead aluminum" through a biomimetic mechanical enhancement mechanism that combines mechano-electrochemical processes, thus endowing the anode with outstanding structural robustness. Aluminum-ion batteries assembled based on this biomimetic CNT / Al composite metal anode exhibit groundbreaking ultra-long cycle stability under harsh high-rate conditions, providing a highly commercially promising solution for large-scale energy storage.

[0045] Example 1 Preparation and intrinsic performance testing of biomimetic CNT / Al composite metal anode The preparation of a biomimetic aluminum-based composite metal anode includes the following steps: (1) Spherical aluminum powder with a particle size of about 10 µm and a purity of >99.5% was placed in a planetary ball mill and ball-milled at a precise speed of 423 r / min at room temperature for 1.5 h to convert it into two-dimensional micro-nano aluminum sheets.

[0046] (2) Carboxylated multi-walled carbon nanotubes (MWCNTs) with a diameter of 30-50 nm and a length of about 2 µm were sonicated for 2 h to form a suspension; (3) Modify two-dimensional micro / nano aluminum sheets with a PVA solution containing 1700-1800 repeating units; (4) Add the MWCNT suspension dropwise to the modified two-dimensional micro-nano aluminum sheet solution under stirring. The mass ratio of carbon nanotubes to two-dimensional micro-nano aluminum sheets is 1:99. Continue until the system color changes completely from black to transparent. Filter and wash with deionized water to obtain CNT / Al composite powder.

[0047] (5) The composite powder was heat-treated at 500 °C for 2 h under an argon flow; it was then transferred to a mold and cold-pressed into a dense block at 500 MPa; it was then sintered at 550 °C for 2 h under argon protection; and finally rolled at 500 °C using a roll-to-roll hot extrusion press to prepare a 150 µm thick CNT / Al metal foil.

[0048] (6) The metal foil is mechanically polished to a thickness of 100 ± 5 µm, punched into a circular piece with a diameter of 10 mm, ultrasonically cleaned with acetone and ethanol in sequence, and dried at 80 °C for 12 h to obtain the final electrode.

[0049] Comparative Example 1 Standard commercial aluminum foil with a thickness of 100 µm was used, cut into the same size, cleaned, and dried for later use. This comparative example was used to compare the performance of symmetrical batteries with Example 1.

[0050] To eliminate the interference of structural degradation or capacity decay of the positive electrode material (such as graphite) during cycling, and to separately verify the intrinsic structural stability and dendrite suppression ability of the biomimetic CNT / Al composite metal negative electrode of this invention, this embodiment first assembles a symmetrical battery for specific testing. Specifically, using the biomimetic CNT / Al composite metal negative electrode of Example 1 (or the pure aluminum electrode of Comparative Example 1) as the positive and negative electrodes, a glass fiber membrane as the separator, and AlCl3-EMIMCl ionic liquid as the electrolyte, a symmetrical battery is assembled in an argon-protected glove box. Electrochemical tests show that: Figure 2 As shown, at 1 mA·cm -2 At current density, the CNT / Al composite metal anode of Example 1 exhibited an extremely low nucleation overpotential of 100 mV, a 42% reduction compared to the commercial pure aluminum electrode (175 mV). Figure 2 ); The CNT / Al||CNT / Al symmetric cell of Example 1 at 1 mA·cm -2 0.5 mAh·cm -2 It can cycle stably for over 1500 hours, while the commercial aluminum foil symmetric cell (Al||Al) in Comparative Example 1 failed due to dendrite piercing the separator and short-circuiting within a short time. Figure 3 More significantly, at 5 mA·cm -2 Under the harsh conditions of high rate (high current density), this biomimetic negative electrode can still cycle stably for 650 h, while the commercial aluminum foil symmetric cell (Al||Al) of Comparative Example 1 fails rapidly due to short circuit within 30 h under the same harsh conditions. Figure 4 ).

[0051] In addition, nanoindentation testing (at 1 mA·cm) -2 0.5 mAh·cm -2 Cycling for 100 hours under certain conditions showed that traditional pure aluminum anodes are prone to severe plastic deformation and structural collapse after cycling, leading to the breakage and peeling of active aluminum and the formation of "dead aluminum" that cannot participate in the reaction. In contrast, the biomimetic CNT / Al composite metal anode of Example 1 of this invention exhibits significantly improved hardness and excellent elastic recovery ability, effectively ensuring the structural integrity and mechanical stability of the electrode during long-term cycling. Figure 5 ).

[0052] Example 2 Application of biomimetic CNT / Al composite metal anode in aluminum-ion batteries (full cell assembly and testing) (1) Preparation of positive electrode: Artificial graphite, conductive carbon black and polyvinylidene fluoride (PVDF, solvent is N-methylpyrrolidone) are mixed in a mass ratio of 8:1:1 and stirred thoroughly to obtain a uniform slurry; the slurry is uniformly coated on molybdenum foil with a scraper, dried in a forced air at 80 ℃ for 4 h, densified by a roller press, punched into a 10 mm diameter disc, and finally transferred to a vacuum drying oven and dried at 110 ℃ for 24 h, and naturally cooled to obtain artificial graphite positive electrode.

[0053] (2) Full cell assembly: The biomimetic CNT / Al composite metal anode prepared in Example 1 was used as the anode material for assembling aluminum-ion batteries.

[0054] An aluminum-ion battery specifically comprises a negative electrode, a positive electrode, a separator, and an electrolyte, and its specific assembly parameters are as follows: Negative electrode: The biomimetic CNT / Al composite metal negative electrode prepared in Example 1; Positive electrode: Artificial graphite positive electrode prepared using the above step (1); Separator: Fiberglass diaphragm is selected; Electrolyte: An aluminum-based ionic liquid electrolyte is selected (in this embodiment, AlCl3-1-ethyl-3-methylimidazolium chloride ionic liquid is used, and the molar ratio of AlCl3 to 1-ethyl-3-methylimidazolium chloride is 1.3:1).

[0055] The assembly process of the above-mentioned full batteries was completed in an argon-protected glove box.

[0056] Comparative Example 2 It is basically the same as Example 2, except that the commercial pure aluminum electrode from Comparative Example 1 is used as the negative electrode to assemble the full cell.

[0057] The full cells assembled in Example 2 and Comparative Example 2 were subjected to 5 A·g. -1 Constant current charge-discharge cycle tests were conducted at high current densities. The results show that the full cell of Example 2 can achieve 45,000 stable cycles with a capacity retention of over 80% after cycling, and its long-cycle stability is far superior to that of the full cell in Comparative Example 2 matched with a pure aluminum anode.

[0058] Example 3 The preparation method is basically the same as that in Example 1, except that in step (4), the mass ratio of carbon nanotubes to aluminum powder is controlled to be 1.5:98.5. The electrode was tested under the same conditions as in Examples 1 and 2, and the prepared electrode also has excellent electrochemical performance and anti-dendritic ability.

[0059] Comparative Example 3 The preparation steps of this comparative example are basically the same as those of Example 1, except that the "ball milling morphology control" process in step (1) is omitted. Conventional spherical aluminum powder with an initial particle size of about 10 µm is directly modified with PVA surface and then mixed with carboxylated multi-walled carbon nanotube suspension. The subsequent cold pressing, sintering and hot extrusion calendering processes are the same as those in Example 1.

[0060] Due to the significant geometrical differences (curvature mismatch) between the aluminum matrix and the carbon nanotube network, the carbon nanotubes are prone to severe bending, entanglement, and macroscopic agglomeration during slurry mixing and densification. This agglomeration typically leads to stress concentration sites and microcrack initiation within the composite material, resulting in extremely high brittleness and easy fracture, making it difficult to form in rolling processes. Therefore, subsequent electrochemical assembly and testing were not performed.

[0061] Comparative Example 4 The preparation steps of this comparative example are basically the same as those of Example 1, except that the PVA surface modification process in step (3) is completely removed, and the "carboxylated multi-walled carbon nanotubes" in step (2) are replaced with ordinary "unfunctionalized multi-walled carbon nanotubes".

[0062] Because only weak van der Waals forces can be formed between the unfunctionalized carbon nanotubes and the untreated aluminum particles, the CNTs are easily detached during subsequent slurry mixing and washing (the filtrate remains black and turbid, failing to achieve the transparent state described in Example 1). Under strong mechanical stress such as hot extrusion, phase separation easily occurs because the carbon and aluminum phases cannot effectively transfer load, leading to a sharp decline in the material's mechanical properties, thus making subsequent battery assembly testing impossible.

[0063] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. An aluminum-ion battery based on a biomimetic CNT / Al composite metal anode, characterized in that, It consists of a positive electrode, a non-aqueous aluminum salt-based ionic liquid electrolyte, a membrane, and a biomimetic CNT / Al composite metal negative electrode; The biomimetic CNT / Al composite metal anode consists of an aluminum matrix and a three-dimensional continuous electron permeation network formed inside the aluminum matrix. The aluminum matrix is ​​a micro-nano-scale aluminum sheet, and the three-dimensional continuous electron permeation network is formed by carboxylated multi-walled carbon nanotubes. The three-dimensional continuous electron permeation network extends to the surface of the biomimetic CNT / Al composite metal anode.

2. The aluminum-ion battery based on a biomimetic CNT / Al composite metal anode according to claim 1, characterized in that, The thickness of the biomimetic CNT / Al composite metal anode is 10~200 μm.

3. An aluminum-ion battery based on a biomimetic CNT / Al composite metal anode according to claim 1 or 2, characterized in that, The thickness of the biomimetic CNT / Al composite metal anode is 100 ± 5 μm.

4. The aluminum-ion battery based on a biomimetic CNT / Al composite metal anode according to claim 1, characterized in that, In the biomimetic CNT / Al composite metal anode, the mass ratio of carbon nanotubes to aluminum matrix is ​​0.5:99.5~2:

98.

5. An aluminum-ion battery based on a biomimetic CNT / Al composite metal anode according to claim 1, characterized in that, The biomimetic CNT / Al composite metal anode was prepared by the following method: S1: Ball milling is performed on spherical aluminum powder to cause plastic deformation and transform it into two-dimensional micro / nano aluminum sheets; the surface of the two-dimensional micro / nano aluminum sheets is modified with polyvinyl alcohol to obtain a dispersion of two-dimensional micro / nano aluminum sheets. S2: Carboxylated multi-walled carbon nanotubes are ultrasonically dispersed in water to prepare an aqueous suspension; the aqueous suspension is added to the dispersion of two-dimensional micro / nano aluminum sheets obtained in step S1, and then separated to obtain CNT / Al composite powder; S3: The CNT / Al composite powder obtained in step S2 is densified to obtain CNT / Al composite metal foil; S4: The CNT / Al composite metal foil obtained in step S3 is finely processed to obtain a biomimetic CNT / Al composite metal anode.

6. The aluminum-ion battery based on a biomimetic CNT / Al composite metal anode according to claim 5, characterized in that, In step S1, the ball milling speed is 400~450 r / min, and the ball milling time is 1~2 h; the thickness of the two-dimensional micro / nano aluminum sheet is 200~800 nm; and the polyvinyl alcohol contains 1700~1800 repeating units.

7. An aluminum-ion battery based on a biomimetic CNT / Al composite metal anode according to claim 5, characterized in that, In step S2, the diameter of the carboxylated multi-walled carbon nanotubes is 30~50 nm; the ultrasonic dispersion time is 2 h.

8. An aluminum-ion battery based on a biomimetic CNT / Al composite metal anode according to claim 5, characterized in that, In step S3, the densification process includes impurity removal, cold pressing, sintering, and hot extrusion. The impurity removal process is: heat treatment; The cold pressing is performed at a pressure of 500 MPa. The sintering process is as follows: sintering at 500~600 ℃ for 1~3 h under argon protection; The hot extrusion is a rolling process at 500 °C.

9. An aluminum-ion battery based on a biomimetic CNT / Al composite metal anode according to claim 5, characterized in that, In step S4, the finishing process includes surface treatment, punching, cleaning, and drying.

10. An aluminum-ion battery based on a biomimetic CNT / Al composite metal anode according to claim 1, characterized in that, The positive electrode is one of artificial graphite, natural graphite, activated carbon, transition metal sulfides, and conductive polymers. The diaphragm is a glass fiber diaphragm; The non-aqueous aluminum-based ionic liquid electrolyte is a mixture of AlCl3 and 1-ethyl-3-methylimidazolium chloride.

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