Dynamic lithium metal negative electrode current collector based on pressure triggered swellable structure and method of making same

Abstract

This invention discloses a dynamic lithium metal anode current collector based on a pressure-triggered expandable structure and its preparation method. The current collector comprises a bottom conductive nucleation layer and an upper dynamic functional layer. The bottom conductive nucleation layer is composed of a porous copper framework, which is a brass mesh that has undergone selective dealloying treatment. The lower half of the porous copper framework is surface-modified with an array of lithium-affinity nanoparticles. The upper dynamic functional layer is a wrinkled graphene-PDMS composite layer. Through the dual-layer composite design of the bottom conductive nucleation layer and the upper dynamic functional layer, combined with weakly bonded lattice connections and pre-set micro-expansion channels, the current collector can adaptively expand with the accumulation of internal pressure during lithium deposition, continuously providing an ordered growth space for lithium metal, and achieving a functional leap from passive guidance to active response and spatial regeneration.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, specifically to a dynamic lithium metal anode current collector based on a pressure-triggered expandable structure and its preparation method. Background Technology

[0002] Lithium metal is widely recognized as the most promising next-generation anode material due to its extremely high theoretical specific capacity and the lowest electrochemical potential. In contrast, the theoretical capacity of graphite anodes used in traditional lithium-ion batteries is only 372 mAh / g, which is insufficient to meet the urgent energy density requirements of electric vehicles, drones, and portable electronic devices. Among various lithium metal battery configurations, anode-free lithium metal batteries have attracted much attention due to the elimination of pre-fabricated lithium anodes, pushing the overall battery energy density to the extreme, and are considered one of the ultimate choices for high-energy-density batteries.

[0003] However, the core challenges faced by lithium metal during charge-discharge cycling have not been fundamentally resolved. During the first charge, lithium metal needs to be deposited in situ from the electrolyte on the current collector surface to form the negative electrode. In subsequent cycles, lithium metal is repeatedly stripped and redeposited on the current collector. During this process, uncontrolled growth of lithium dendrites is highly likely to occur, leading to continuous side reactions at the electrolyte-electrode interface and repeated rupture and reconstruction of the solid electrolyte interphase (SEI) membrane, resulting in the accumulation of a large amount of "dead lithium." These problems directly reduce battery coulombic efficiency and shorten cycle life. In severe cases, lithium dendrites can penetrate the separator, causing internal short circuits or even thermal runaway, posing a significant safety hazard.

[0004] To address these challenges, researchers widely employ a "lithophile" current collector strategy. This involves modifying the current collector surface with materials possessing high lithium affinity (such as nanoparticles or thin films of Ag, Sn, ZnO, Au, etc.) to reduce the lithium nucleation overpotential and guide lithium ions to deposit uniformly at predetermined sites, thereby suppressing dendrite formation. Commonly used methods for preparing lithiophile current collectors include chemical reduction, electrodeposition, magnetron sputtering, and template methods. Regarding substrate materials, three-dimensional porous current collectors, due to their high specific surface area, excellent conductive framework, and mechanical stability, have become important carriers for lithiophile structural design. Three-dimensional frameworks such as porous copper mesh, nickel foam, and carbon fiber cloth can effectively disperse local current density, increase the contact area between the electrode and the electrolyte, and provide more ample space for lithium metal deposition.

[0005] While three-dimensional lithiophilic current collectors have achieved some success in improving the uniformity of lithium deposition, the current mainstream statically guided current collector strategies still suffer from the following fundamental drawbacks. First, spatial limitations: bottom nucleation guidance can only delay dendrite growth in the initial stage. Once the bottom space is gradually filled with lithium metal, subsequent lithium deposition will inevitably grow upwards disorderly, forming a "stacking effect" at the top of the current collector, leading to a large accumulation of dendrites and dead lithium. Second, irreversible structural damage: the volume expansion effect of lithium metal deposition will exert continuous mechanical stress on the current collector framework, causing the porous structure to compress, collapse, or even fracture, destroying the original three-dimensional conductive network and causing a sharp increase in interface impedance. Third, static functionality: existing modified structures are fixed after fabrication and cannot sense or respond to dynamic pressure changes caused by lithium deposition during battery operation, lacking adaptive control capabilities. Fourth, limited cycle stability: the combined effect of the above structural failures and interface instability leads to rapid capacity decay and a continuous decrease in coulombic efficiency during long-term cycling.

[0006] Ultimately, existing technologies fail to address the core challenge of "how to continuously accommodate volume changes caused by lithium metal deposition within a limited space." Current static current collector strategies essentially rely on the one-time use of limited initial space and cannot dynamically adapt to changes in lithium deposition throughout the battery's lifespan. Therefore, there is an urgent need to develop an intelligent current collector with dynamic capacity expansion capabilities that can co-evolve with the lithium deposition process, fundamentally breaking through the bottleneck of fixed space and achieving a functional leap from passive guidance to active response and space regeneration. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the aforementioned background technology and provide a dynamic lithium metal anode current collector based on a pressure-triggered expandable structure and its preparation method. This current collector employs a dual-layer composite design of a bottom conductive nucleation layer and an upper dynamic functional layer, combined with weakly bonded lattice connections and pre-set micro-expansion channels. This allows the current collector to adaptively expand as internal pressure accumulates during lithium deposition, continuously providing an orderly growth space for lithium metal, achieving a functional leap from passive guidance to active response and spatial regeneration.

[0008] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a dynamic lithium metal anode current collector based on a pressure-triggered expandable structure. The current collector is a two-layer composite three-dimensional structure, including a bottom conductive nucleation layer and an upper dynamic functional layer.

[0009] The bottom conductive nucleation layer is composed of a porous copper framework, which is a brass mesh that has undergone selective dealloying treatment. The lower half of the porous copper framework is modified with an array of lithium-loving nanoparticles. The lithium-loving nanoparticles are selected from one or more of Ag, Sn, ZnO, In, Pb, and Bi, and have a particle size of 5~50 nm.

[0010] Preferably, the porous copper skeleton has a porosity of ≥80% and a pore size of 50~200 μm.

[0011] Preferably, the lithiophilic nanoparticle array modifies the lower half of the porous copper framework, which accounts for 50% to 70% of the total height. The lithiophilic nanoparticles are Ag nanoparticles with a particle size of 10 to 30 nm. Selective dealloying is performed using HCl solution at 30 to 50°C to remove the Zn component from the brass. Utilizing the electrochemical activity difference of preferential dissolution of Zn in the copper-zinc two-phase alloy, an interconnected three-dimensional porous framework structure spontaneously forms under mild acidic conditions. This porous copper framework retains the excellent conductivity and mechanical strength of copper while providing ample internal space and a uniform current distribution environment for lithium metal deposition through its high porosity and suitable pore size distribution. Modifying the lower half of the porous copper framework with lithiophilic nanoparticles, rather than the entire surface, aims to guide lithium ions to preferentially nucleate at the bottom of the current collector, establishing a bottom-up ordered deposition pattern and avoiding the "top-stacking" effect caused by preferential lithium deposition at the top of the current collector.

[0012] Preferably, the upper dynamic functional layer is composed of a conductive material with vertically arranged microstructures. These microstructures are wrinkled and initially in a dense, compressed state. The upper dynamic functional layer is connected to the lower conductive nucleation layer via a weak bonding lattice and has multiple pre-set micro-expansion channels extending vertically. The bonding force between the upper dynamic functional layer and the lower conductive nucleation layer is less than the local shear stress threshold generated by lithium deposition. The elastic modulus of the upper dynamic functional layer is 1~50 MPa. This ensures that when the internal mechanical pressure reaches the pre-set threshold during lithium deposition, the weak bonding lattice is locally disrupted, and the wrinkled structure unfolds upwards along the micro-expansion channels, providing an ordered growth space for lithium metal.

[0013] Preferably, the upper dynamic functional layer is a wrinkled graphene-PDMS composite layer, wherein the wrinkled graphene is a periodic wrinkled structure formed by transferring a vertically aligned graphene array grown on a NaCl single crystal substrate by chemical vapor deposition to a pre-stretched PDMS elastomer substrate and releasing stress. The thickness of the graphene array is 50~100nm and the aspect ratio is greater than 10.

[0014] Preferably, the wavelength of the periodic pleated structure is 5~20 μm, the amplitude is 1~5 μm, and the pre-stretch rate of the PDMS elastomer substrate is 150%~200%. The design principle of this pleated structure is that the graphene array spontaneously buckles due to dimensional mismatch when the pre-stretched PDMS substrate shrinks, forming periodic ripples. This pleated structure is initially in a dense, compressed state, occupying a very small volume. However, when subjected to pressure along the expansion channel, the pleats can unfold step by step, releasing several times the initial volume of space, achieving "space supply on demand." The excellent conductivity of graphene ensures that the newly exposed surface after unfolding still has good electron transport capabilities, preventing electrical contact interruption due to deformation.

[0015] Preferably, the weakly bonded lattice is made of PVDF material and formed between the upper dynamic functional layer and the lower conductive nucleation layer using lattice electrospinning technology. The anchoring point spacing is 100~300 μm, and the PVDF solution concentration used is 5~10 wt%. The core function of the weakly bonded lattice is to provide sufficient bonding force in the initial state after the current collector is assembled to maintain the integrity and positioning accuracy of the bilayer structure. Simultaneously, its bonding strength is intentionally designed to be lower than the local shear stress threshold caused by lithium deposition. When the mechanical pressure caused by local lithium deposition exceeds the critical failure strength of the weakly bonded point, the anchoring point is selectively fractured in that region, releasing the deformation freedom of the upper folded structure and allowing it to unfold along the micro-expansion channels. This cascade response mechanism of "controlled fracture-ordered unfolding" ensures the spatial orderliness of the expansion process and avoids the overall collapse of the structure.

[0016] The preset threshold for pressure-triggered expansion is preferably 0.5~5 MPa. This threshold is controlled by adjusting the elastic modulus of the upper dynamic functional layer, the connection strength of the weakly bonded lattice, and the spacing of the micro-expansion channels.

[0017] Furthermore, the inner wall of the micro-expansion channel is lithiophilic, which is imparted by at least one of surface oxidation treatment, heteroatom doping, or loading a lithiophilic catalyst, so that the lithium metal deposition front preferentially fills the newly released space immediately following the expansion interface, achieving a dynamic balance of expansion and filling simultaneously.

[0018] The current collector described in this invention achieves a three-stage dynamic response during lithium deposition. The first stage is the initial nucleation guidance stage: lithium ions enter the current collector under the drive of an electric field. Driven by the chemical affinity of the lower half of the conductive nucleation layer's lithium-loving nanoparticles and the local electric field, they preferentially and uniformly nucleate on the surface of the lithium-loving sites. The second stage is the pressure-triggered expansion stage: as the lithium deposition layer gradually thickens, the mechanical pressure exerted by the lithium metal on the inner wall of the current collector continuously accumulates. When the local pressure reaches a preset threshold, the weakly bonded lattice undergoes selective destruction in this region, and the dense, compressed, wrinkled structure gradually unfolds upwards along the micro-expansion channels, releasing new deposition space. The third stage is the adaptive ordered filling stage: the newly opened expansion channel's inner wall, due to its lithium-loving properties, guides the lithium metal to orderly fill the newly released space along the channel direction. The filling process is synchronized with the expansion process, forming a self-regulating dynamic balance of "expansion-filling simultaneously." Simultaneously, after the lithium metal is stripped during discharge, the expansion channel can partially retract under the action of elastic restoring force, maintaining structural integrity and preparing for the next cycle.

[0019] Secondly, the present invention provides a method for preparing the above-mentioned dynamic lithium metal anode current collector based on a pressure-triggered expandable structure, comprising the following steps: Step 1: Preparation of the underlying conductive nucleation layer: A brass mesh is selectively dealloyed with HCl solution at 30-50°C for 2-6 hours to remove Zn components, resulting in a porous copper mesh. After ultrasonic cleaning and drying, the porous copper mesh is placed in a magnetron sputtering system, where a lithiophilic nanoparticle array is sputtered onto the lower half of the porous copper mesh to obtain the underlying conductive nucleation layer.

[0020] Step 2: Preparation of the dynamic functional layer: A vertically aligned graphene array is grown on a NaCl single-crystal substrate using chemical vapor deposition (CVD) to obtain a graphene film. The preferred growth temperature for CVD is 950–980 °C, the carbon source to hydrogen flow ratio is 1:(9–12), the growth time is 8–15 min, and the resulting graphene film has a thickness of 50–100 nm, an aspect ratio greater than 10, and a resistivity less than 200 Ω / sq. The graphene film is transferred to a pre-stretched PDMS elastomer substrate, and the pre-stretch stress is released to form a graphene layer with a periodic wrinkled structure. The preferred pre-stretch ratio of the PDMS elastomer substrate is 150%–200%, and the wavelength of the formed periodic wrinkled structure is 5–20 μm, with an amplitude of 1–5 μm. A PVDF solution is sprayed at specific nodes of the wrinkled structure using lattice electrospinning technology to form weakly connected anchor points. After drying, a wrinkled graphene-PDMS composite layer is obtained. The needle tip spacing of the dot matrix electrospinning is preferably 100~300 μm, and the concentration of the PVDF solution is 5~10 wt%.

[0021] Step 3: Assembly of the bilayer composite structure: Align the wrinkled graphene-PDMS composite layer with the upper half of the bottom conductive nucleation layer, and heat it to 60-80°C under vacuum or inert atmosphere to partially soften the PDMS and enhance interfacial contact. The heating time is 0.5-2 hours. Subsequently, slowly release the tensile stress to allow the composite layer to naturally adhere to the surface of the porous copper mesh. Remove residual PDMS by cleaning with deionized water or ethanol to obtain a bilayer composite three-dimensional dynamic current collector anchored by PVDF lattice.

[0022] Preferably, the brass mesh has a mesh size of 100-300, the HCl solution has a concentration of 1-2 M, and the porous copper mesh obtained after dealloying has a porosity ≥80% and a pore size of 50-200 μm. The preferred magnetron sputtering process parameters are: sputtering power 100-200 W, Ar gas pressure 0.5 Pa, deposition time 10-30 min, and the lithiophilic nanoparticles are Ag nanoparticles with a particle size of 10-30 nm. The ultrasonic cleaning step includes sequential cleaning with acetone, ethanol, and deionized water for 5-10 min each.

[0023] Compared with the prior art, the present invention has the following advantages: Firstly, the current collector of this invention employs a "wrinkled graphene-PDMS" composite structure as a dynamic functional layer. A weak connection design is achieved through PVDF lattice anchoring, allowing the upper graphene wrinkles to vertically expand along micro-expansion channels under the internal pressure generated by lithium deposition, continuously providing ordered deposition space for lithium metal. This "space-on-demand supply" mechanism fundamentally breaks through the bottleneck of "fixed space" in static current collectors, effectively buffering volume changes during lithium metal deposition-stripping. Experimental results show that the optimized scheme achieves a capacity retention rate of up to 94.28% after 50 cycles, far superior to traditional planar copper foil and static lithium-friendly copper mesh. Simultaneously, the ordered space release suppresses disordered lithium accumulation and dendrite penetration; after 500 hours of cycling, the overpotential of the symmetrical battery only increases to 24.6 mV, and the interface impedance increase is less than 30%, confirming the decisive role of this dynamic structure in maintaining interface stability.

[0024] Secondly, this invention utilizes bottom-priority nucleation guidance to achieve ordered deposition from the bottom up. The lithium-loving nanoparticle array modified in the lower half of the porous copper mesh guides lithium ions to preferentially and uniformly nucleate at the bottom of the current collector by reducing the local nucleation overpotential and homogenizing the surface electric field distribution, establishing a "bottom-up" sequential deposition mode. This design coordinates the lithium deposition direction with the fold unfolding direction, ensuring the effective operation of the three-stage dynamic response mechanism. Test data shows that when Ag nanoparticles are modified in the lower half of the copper mesh, the deposition overpotential is only 7.9 mV, while when modified in the upper half, the overpotential increases sharply to 37.5 mV, and the cycling performance deteriorates severely, fully demonstrating the irreplaceable key role of bottom nucleation guidance in the overall technical solution. In addition, the synergistic effect of the high specific surface area of ​​the porous copper framework and the vertically arranged graphene array effectively reduces the local current density, achieving a low rate of 5 mA cm⁻¹. -2 It still maintains 85.8% capacity output, demonstrating excellent high-rate performance.

[0025] Third, this invention achieves controllable anchoring and cascaded response through a weakly bonded lattice. By employing electrospinning lattice-type PVDF anchoring technology, a weak connection design is achieved between the dynamic functional layer and the underlying conductive nucleation layer. This maintains the integrity and positioning accuracy of the bilayer structure in the initial state while ensuring that the anchoring points can selectively fracture when the lithium deposition pressure exceeds a critical threshold, releasing the deformation freedom of the unfolding wrinkles. This "controllable fracture-ordered unfolding" cascaded response mechanism avoids the structural brittleness caused by strong adhesion and also prevents the arbitrary slippage of the functional layer when there is no connection.

[0026] Fourth, regarding the types of lithium-loving nanoparticles, experiments have confirmed that various lithium-loving materials, such as Ag, Sn, ZnO, and Ag / Sn composites, can effectively function in the current collector structure of this invention, demonstrating flexibility and wide applicability in material selection. The temperature at each step in the overall process does not exceed 1000℃, and the assembly step only requires low-temperature treatment at 60-80℃, which helps reduce manufacturing costs. Furthermore, the PDMS substrate endows the current collector with excellent flexibility and stretchability, making it a promising candidate for integration into flexible devices, meeting the demand for flexible and stretchable batteries in wearable electronic devices.

[0027] Fifth, the current collector of this invention achieves a three-stage dynamic response during lithium deposition: nucleation guidance, pressure-triggered expansion, and adaptive ordered filling. Each stage is tightly integrated and organically synergistic. The first stage guides uniform nucleation through lithiophilic sites; the second stage releases new space through the controllable fracture and wrinkle unfolding of the weakly bonded lattice; and the third stage guides ordered lithium filling through the lithiophilicity of the inner wall of the expansion channel. These three stages form a self-consistent cyclic regulation system. Crucially, during discharge, the expansion channel can partially retract under elastic restoring force, maintaining structural integrity and preparing for the next cycle, ensuring reversible utilization of the structure. Comprehensive comparative analysis shows that the organic combination of the underlying lithiophilic nanoparticle array, the PVDF weakly bonded lattice, and the pre-stretched wrinkled graphene functional layer is a necessary condition for achieving the excellent performance of the current collector; none of these can be omitted. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the process for preparing a dynamic lithium metal anode current collector based on a pressure-triggered expandable structure. Detailed Implementation

[0029] The following describes in detail the embodiments of the dynamic lithium metal anode current collector based on a pressure-triggered expandable structure and its preparation method according to the present invention. This description is provided to enable those skilled in the art to fully understand the invention and is not intended to limit the subject matter described in the claims.

[0030] The "scope" disclosed in this invention is defined in the form of a lower limit and an upper limit. A given scope is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific scope. The scope defined in this way can include or exclude end values, and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a scope.

[0031] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined to form new technical solutions. All technical features and optional technical features of the present invention can be combined to form new technical solutions. All steps of the present invention can be performed sequentially or randomly.

[0032] I. Implementation Examples Example 1 Step 1: Take a 200-mesh commercial brass mesh (Cu-Zn alloy, Zn content approximately 35 wt%) and cut it into circular pieces with a diameter of 16 mm. Immerse the pieces in a 1.5 M hydrochloric acid (HCl) solution and perform selective dealloying treatment at a constant temperature of 40℃ for 4 hours to fully dissolve the Zn component in the brass. After the reaction, remove the copper mesh and rinse it three times each with deionized water and anhydrous ethanol to obtain a porous copper mesh. Scanning electron microscopy (SEM) characterization showed that the obtained porous copper mesh had a porosity of approximately 85%, with pore sizes distributed in the range of 120–180 μm, exhibiting a uniformly interconnected three-dimensional porous framework structure.

[0033] Step 2: The porous copper mesh was sequentially ultrasonically cleaned in acetone, anhydrous ethanol, and deionized water for 10 minutes each to remove residual impurities and organic matter from the surface. After cleaning, it was dried in a vacuum drying oven at 60°C for 2 hours, and then transferred to the sample stage of the magnetron sputtering system.

[0034] Step 3: An Ag nanoparticle array was deposited in the lower half of the porous copper mesh (60% of the total height of the copper mesh) using DC magnetron sputtering. The sputtering target was 99.99% pure Ag, and the sputtering parameters were: sputtering power 150 W, working gas high-purity Ar, Ar pressure 0.5 Pa, no substrate heating, and deposition time 20 min. After deposition, the nanoparticles were characterized by SEM and atomic force microscopy (AFM). The Ag nanoparticles were found to be uniformly distributed in an island-like pattern on the surface of the copper mesh, with an average particle size of 20–25 nm and a coverage density of approximately 1.8 × 10⁻⁶. 11 particles / cm 2 .

[0035] Step 4: Vertically aligned graphene arrays were grown on a NaCl single-crystal substrate (10 mm × 10 mm) using atmospheric pressure chemical vapor deposition (CVD). The CVD process parameters were: growth temperature 950℃, high-purity CH4 as the carbon source, H2 as the carrier gas, CH4 / H2 flow ratio 1:9, and growth time 15 min. After growth, the substrate was allowed to cool naturally to room temperature. Raman spectroscopy and SEM characterization showed that the obtained graphene film had a thickness of approximately 70 nm, an aspect ratio >15, and a sheet resistance <200 Ω / sq, exhibiting good conductivity and structural continuity.

[0036] Step 5: The obtained graphene film was transferred from the NaCl substrate to a pre-stretched PDMS elastomer substrate (200% stretched) using a PMMA-assisted transfer method. After the transfer was completed and the PMMA was dissolved and removed, the PDMS prestress was slowly released. The graphene film spontaneously formed a periodic wrinkled structure due to substrate shrinkage. Characterized by optical microscopy and AFM, the wrinkles had a wavelength of approximately 10 μm and an amplitude of approximately 3 μm, with parallel directions and a regular arrangement.

[0037] Step Six: Weakly connected anchor points were constructed at specific nodes of the wrinkled graphene structure using lattice electrospinning technology. The electrospinning parameters were: needle tip spacing 200 μm, PVDF solution concentration 8 wt% (solvent being a 7:3 volume ratio of DMF / acetone), spinning voltage 15 kV, and receiving distance 12 cm. After spinning, the material was allowed to air dry at room temperature for 24 h to form a weakly connected network composed of PVDF nanofiber lattices, resulting in a "wrinkled graphene-PDMS" composite layer.

[0038] Step 7: Align and attach the above-mentioned "wrinkled graphene-PDMS" composite layer to the upper half of the porous copper mesh prepared in Step 3 (i.e., the area without Ag sputtering), so that the wrinkle direction is parallel to the plane of the copper mesh.

[0039] Step 8: Place the bonded sample in a vacuum oven and heat at 70°C for 1 hour to soften the PDMS substrate and create a van der Waals force-enhanced interfacial contact with the copper mesh surface. Then, while maintaining the temperature, slowly release the residual tensile stress (release rate approximately 0.5 mm / min) to allow the "wrinkled graphene-PDMS" composite layer to naturally adhere to the copper mesh skeleton surface.

[0040] Step 9: After cooling to room temperature, rinse three times with deionized water to remove any incompletely cured residual PDMS. The final result is a bilayer dynamic current collector composed of a wrinkled graphene dynamic functional layer anchored solely by a PVDF lattice and a porous copper mesh substrate. This current collector exhibits a dense, wrinkled state with a thickness of approximately 120 μm under no external force. Under the internal pressure generated by lithium deposition, the wrinkles can vertically expand along the region between the anchor points, reaching a thickness of approximately 200 μm, demonstrating excellent reversible deformation capability.

[0041] Example 2 The preparation method of Example 2 is basically the same as that of Example 1, except that the sputtering deposition position of Ag nanoparticles in step three is different: the Ag sputtering area is adjusted to the upper half of the copper mesh (accounting for 60% of the total height), that is, the side that is in direct contact with the graphene functional layer. All other process parameters and operating steps are completely consistent with those of Example 1.

[0042] Example 3 The preparation method of Example 3 is basically the same as that of Example 1, except that the magnetron sputtering process parameters in step three are different: the sputtering power is adjusted to 100 W, the Ar gas pressure is adjusted to 0.3 Pa, and the deposition time is extended to 30 min, while the other conditions remain unchanged. The average particle size of the obtained Ag nanoparticles is 5~10 nm.

[0043] Example 4 The preparation method of Example 4 is basically the same as that of Example 1, except that the needle tip spacing of the dot matrix electrospinning in step six is ​​different: the spacing is adjusted to 500 μm (200 μm in Example 1), the PVDF solution concentration is still 8 wt%, and the other parameters remain unchanged.

[0044] Example 5 The preparation method of Example 5 is basically the same as that of Example 1, except that the pre-stretching ratio of the PDMS elastomer substrate is different in step five: the pre-stretching ratio is reduced from 200% to 150%. The pleated structure formed after stress release has a wavelength of about 12 μm and an amplitude of about 2 μm. The pleat depth and unfoldable space are both reduced compared to Example 1.

[0045] Example 6 The preparation method of Example 6 is basically the same as that of Example 1, except that the CVD growth time in step four is different: the growth time is shortened from 15 min to 8 min. The thickness of the resulting graphene film is about 30 nm.

[0046] Example 7 The preparation method of Example 7 is basically the same as that of Example 1, except that the dealloying treatment conditions in step one are different: 100-mesh commercial brass mesh (Zn content of about 30 wt%) is used, and selectively dealloyed at 30°C for 6 hours with 1 M HCl solution. The resulting porous copper mesh has a porosity of about 80% and a pore size distribution in the range of 50~120 μm. The remaining steps and parameters are the same as in Example 1.

[0047] Example 8 The preparation method of Example 8 is basically the same as that of Example 1, except that the dealloying treatment conditions in step one are different: a 300-mesh commercial brass mesh (Zn content of about 40 wt%) is used, and selectively dealloyed at 50°C for 2 hours using a 2 M HCl solution. The resulting porous copper mesh has a porosity of about 92% and a pore size distribution in the range of 160~200 μm. The remaining steps and parameters are the same as in Example 1.

[0048] Example 9 The preparation method of Example 9 is basically the same as that of Example 1, except that the magnetron sputtering process parameters in step three are different: sputtering power 100 W, Ar gas pressure 0.5 Pa, deposition time 10 min, and Ag sputtering area accounting for 50% of the total height of the copper mesh. Characterization showed that the obtained Ag nanoparticles had an average particle size of approximately 10-15 nm and a coverage density of approximately 1.0 × 10⁻⁶. 11 particles / cm 2 The remaining steps and parameters are the same as in Example 1.

[0049] Example 10 The preparation method of Example 10 is basically the same as that of Example 1, except that the magnetron sputtering process parameters in step three are different: sputtering power 200 W, Ar gas pressure 0.5 Pa, deposition time 30 min, and Ag sputtering area accounting for 70% of the total height of the copper mesh. Characterization showed that the obtained Ag nanoparticles had an average particle size of approximately 28-32 nm and a coverage density of approximately 2.8 × 10⁻⁶. 11 particles / cm 2 The remaining steps and parameters are the same as in Example 1.

[0050] Example 11 The preparation method of Example 11 is basically the same as that of Example 1, except that the CVD growth conditions in step four are different: growth temperature 900℃, CH4 / H2 flow ratio 1:5, and growth time 20 min. The resulting graphene film has a thickness of about 100 nm, an aspect ratio >12, and a sheet resistance of about 180 Ω / sq. The remaining steps and parameters are the same as those in Example 1.

[0051] Example 12 The preparation method of Example 12 is basically the same as that of Example 1, except that the CVD growth conditions in step four are different: growth temperature 1000℃, CH4 / H2 flow ratio 1:15, and growth time 8 min. The resulting graphene film has a thickness of about 45 nm, an aspect ratio >10, and a sheet resistance of about 160 Ω / sq. The remaining steps and parameters are the same as those in Example 1.

[0052] Example 13 The preparation method of Example 13 is basically the same as that of Example 1, except that the electrospinning parameters in step six are different: the PVDF solution concentration is 5 wt%, and the needle tip spacing is 100 μm. The resulting anchor point fibers have a finer diameter (about 200 nm), a higher distribution density, and slightly lower adhesion strength at a single anchor point. The remaining steps and parameters are consistent with those of Example 1.

[0053] Example 14 The preparation method of Example 14 is basically the same as that of Example 1, except that the electrospinning parameters in step six are different: the PVDF solution concentration is 10 wt%, and the needle tip spacing is 300 μm. The resulting anchor point fibers have a relatively large diameter (about 800 nm), a moderate distribution density, and high adhesion strength at a single anchor point. The remaining steps and parameters are consistent with those of Example 1.

[0054] Example 15 The preparation method of Example 15 is basically the same as that of Example 1, except that the heating conditions in step eight are different: it is kept at 60°C in a vacuum oven for 2 hours, while the other parameters remain unchanged. The lower heating temperature results in a slightly lower degree of PDMS softening, but the extended holding time compensates for the interfacial contact effect to some extent.

[0055] Example 16 The preparation method of Example 16 is basically the same as that of Example 1, except that the heating conditions in step eight are different: it is held at 80°C in an argon atmosphere for 0.5 hours, while the other parameters remain unchanged. The higher heating temperature promotes the full softening of PDMS, and good interfacial contact can be obtained even with a shorter holding time.

[0056] Example 17 The preparation method and parameters of Example 17 were exactly the same as those of Example 1, serving as a confirmatory repeatable example with a pre-stretch rate of 200% to verify the repeatability of the experiment. The resulting wrinkled structure had a wavelength of approximately 10 μm and an amplitude of approximately 3 μm, consistent with Example 1.

[0057] Example 18 The preparation method of Example 18 is basically the same as that of Example 1, except for the sputtering target and process parameters in step three: a Sn target with a purity of 99.99% is used instead of an Ag target, the sputtering power is 120 W, the Ar gas pressure is 0.5 Pa, and the deposition time is 25 min. A Sn nanoparticle layer is deposited in the lower half (60% area) of the copper mesh. The average particle size of the obtained Sn nanoparticles is approximately 15-20 nm. All other steps and parameters are consistent with those of Example 1.

[0058] Example 19 The preparation method of Example 19 is basically the same as that of Example 1, except that reactive magnetron sputtering is used to deposit ZnO nanoparticles instead of Ag in step three: the sputtering target is a Zn target with a purity of 99.99%, the working gas is an Ar / O2 mixture (O2 volume fraction 20%), the total gas pressure is 0.5 Pa, the sputtering power is 100 W, and the deposition time is 20 min, forming a ZnO nanoparticle layer in the lower half (60% region) of the copper mesh. XRD confirmed that it is hexagonal wurtzite ZnO with a particle size of about 20-30 nm. The remaining steps and parameters are consistent with those of Example 1.

[0059] Example 20 The preparation method of Example 20 is basically the same as that of Example 1, except that in step three, a co-sputtering deposition of the Ag / Sn composite nanoparticle layer is used: Ag and Sn targets are used simultaneously, with an Ag target sputtering power of 100 W and a Sn target sputtering power of 80 W, an Ar gas pressure of 0.5 Pa, and a deposition time of 15 min, forming an Ag-Sn alloy nanoparticle layer in the lower half (60% region) of the copper mesh. EDS analysis showed that the atomic ratio of Ag to Sn was approximately 3:1, and the average particle size was approximately 18–22 nm. All other steps and parameters were consistent with those of Example 1.

[0060] Example 21 The preparation method of Example 21 is basically the same as that of Example 1, except for the CVD growth conditions in step four: growth temperature 980℃, CH4 / H2 flow ratio 1:12, and growth time 12 min. The resulting graphene film has a thickness of approximately 55 nm, an aspect ratio >12, and a sheet resistance of approximately 150 Ω / sq. The higher growth temperature and appropriate carbon source ratio result in higher crystallinity of graphene and further improved conductivity. The remaining steps and parameters are consistent with those of Example 1.

[0061] Example 22 The preparation method of Example 22 is basically the same as that of Example 1, except for the sputtering target and process parameters in step three: an In target with a purity of 99.99% was used instead of an Ag target, the sputtering power was 130 W, the Ar gas pressure was 0.5 Pa, and the deposition time was 20 min. An In nanoparticle layer was deposited in the lower half (60% area) of the copper mesh. The resulting In nanoparticles had an average particle size of about 15-25 nm and were uniformly distributed in an island-like pattern. In has a low melting point (156.6 °C) and good lithium affinity, and can form a Li-In alloy phase with lithium, thereby reducing the nucleation overpotential of lithium. The remaining steps and parameters are the same as in Example 1.

[0062] Example 23 The preparation method of Example 23 is basically the same as that of Example 1, except for the sputtering target and process parameters in step three: a 99.99% pure Pb target is used instead of an Ag target, the sputtering power is 120 W, the Ar gas pressure is 0.5 Pa, and the deposition time is 25 min. A Pb nanoparticle layer is deposited in the lower half (60% area) of the copper mesh. The average particle size of the obtained Pb nanoparticles is about 20-30 nm. Pb can form various Li-Pb alloy phases with lithium (such as LiPb, Li3Pb, etc.), which have the ability to reduce the nucleation barrier. The remaining steps and parameters are the same as in Example 1.

[0063] Example 24 The preparation method of Example 24 is basically the same as that of Example 1, except for the sputtering target and process parameters in step three: a Bi target with a purity of 99.99% is used instead of an Ag target, the sputtering power is 110 W, the Ar gas pressure is 0.5 Pa, and the deposition time is 20 min. A Bi nanoparticle layer is deposited in the lower half (60% area) of the copper mesh. The average particle size of the obtained Bi nanoparticles is about 15~25 nm. Bi can form a Li3Bi alloy phase with lithium. This alloying reaction can effectively reduce the nucleation overpotential of lithium and guide uniform deposition. The remaining steps and parameters are the same as in Example 1.

[0064] II. Comparative Example Comparative Example 1 The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that the Ag sputtering deposition step in step three is completely omitted, that is, only a pure porous copper mesh is used as the bottom layer without any lithium-loving nanoparticle modification. The operations and parameters of the remaining steps two, four to nine are completely consistent with those of Example 1. The resulting current collector still has a wrinkled graphene dynamic functional layer, but the surface of the bottom copper mesh lacks lithium-loving nucleation sites.

[0065] Comparative Example 2 The preparation method of Comparative Example 2 is basically the same as that of Example 1, except that the dot matrix electrospinning and PVDF anchoring steps in step six are completely omitted. The "wrinkled graphene-PDMS" composite layer is directly bonded to the upper half of the copper mesh without any PVDF dot matrix spraying. After heating to release stress, the functional layer and the copper mesh are connected only by weak van der Waals forces, without any pre-set anchoring points.

[0066] Comparative Example 3 The preparation method of Comparative Example 3 is basically the same as that of Example 1, except that in step five, the graphene film is transferred onto an unstretched PDMS substrate (PDMS thickness 1 mm, pre-stretch rate 0%). Since the PDMS substrate is unstretched, there is no strain difference during release, and the graphene film does not form a wrinkled structure, remaining flat. The remaining steps are consistent with Example 1. Although the current collector obtained in this comparative example has an Ag lithiophilic layer and PVDF anchoring, it lacks an expandable wrinkled structure.

[0067] Comparative Example 4 Comparative Example 4 uses a 10 μm thick commercial electrolytic copper foil as the current collector, without any dealloying, sputtering deposition, or wrinkle functional layer preparation. The copper foil is directly cut into 16 mm diameter discs, ultrasonically cleaned with acetone and ethanol, and then used directly as the lithium metal anode current collector. This comparative example represents the most basic current collector solution.

[0068] Comparative Example 5 The preparation method of Comparative Example 5 is basically the same as that of Example 1, except that the dealloying treatment time in step one is significantly shortened to 0.5 hours, while the other conditions (1.5 M HCl, 40°C) remain unchanged. Due to the severely insufficient treatment time, Zn removal is incomplete, and the porosity of the resulting copper mesh is only about 45%, with a pore size of 30-50 μm, which is far below the porosity range defined in the claims of this invention, indicating an underdeveloped porous structure. The remaining steps and parameters are consistent with those of Example 1.

[0069] Comparative Example 6 Comparative Example 6 only performed steps one to three of Example 1, i.e., preparing a porous copper mesh after dealloying and sputtering an Ag nanoparticle array, but did not perform the dynamic functional layer preparation and assembly operations of steps four to nine. The resulting current collector is only a porous copper mesh modified with an Ag lithiophilic layer, representing a typical "static lithiophilic current collector" scheme in the prior art, used for comparison with the dynamic current collector of the present invention.

[0070] III. Testing Methods The current collectors prepared in all embodiments and comparative examples of this invention were evaluated for electrochemical performance using the following unified method. All electrochemical tests were conducted using CR2032 coin cells, assembled in an argon-filled glove box with an oxygen content below 0.1 ppm. The electrolyte was 1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) dissolved in a mixed solvent of 1,3-dioxolane / ethylene glycol dimethyl ether (DOL / DME, volume ratio 1:1), with 2 wt% lithium nitrate (LiNO3) added as a film-forming additive. The separator was a Celgard 2500 polypropylene microporous membrane. The testing equipment was a NEWARE BTS-5V battery testing system, with the ambient temperature controlled at 25±2℃.

[0071] 1. Deposition overpotential test: A half-cell was assembled using lithium foil as the counter electrode and the prepared current collector as the working electrode. The overpotential was measured at 1 mA cm⁻¹. -2 Lithium metal was deposited using a constant current density, with a deposition capacity of 10 mAh cm⁻¹. -2 Record the voltage-time curves during the constant current deposition process, and take the voltage difference between the lowest point of the voltage curve (the valley of the nucleation overpotential) and the subsequent voltage plateau as the deposition overpotential value. The lower the deposition overpotential, the stronger the affinity of the current collector for lithium ions and the lower the nucleation barrier.

[0072] 2. Coulombic efficiency test: Using lithium metal foil as the counter electrode and the current collector as the working electrode, the efficiency was measured at 1 mA cm⁻¹. -2 Current density deposition 1 mAh cm -2The lithium metal was then stripped to a cutoff voltage of 1.0 V at the same current density. The coulombic efficiency per cycle was defined as the ratio of stripping capacity to deposition capacity, and 200 cycles were continuously tested to evaluate long-term cycling stability.

[0073] 3. Full Battery Cycle Test: The positive electrode uses commercially available lithium iron phosphate (LiFePO4, LFP). The positive electrode slurry was prepared as follows: LFP active material, polyvinylidene fluoride (PVDF) binder, and conductive carbon black (Super P) were uniformly dispersed in N-methylpyrrolidone (NMP) solvent at a mass ratio of 8:1:1 and stirred for 8 hours until the slurry was homogeneous. The slurry was then coated onto an aluminum foil current collector using a doctor blade coating method, dried in a vacuum drying oven at 80°C for 12 hours, and then cut into circular electrode sheets with a diameter of 12 mm using a die-cutting machine. The areal loading of the active material in the positive electrode sheet was approximately 4.9 mg cm⁻¹. -2 Using the prepared dynamic current collector as the negative electrode and the aforementioned LFP electrode as the positive electrode, a full cell was assembled. The voltage range was 2.5–4.2 V, with a 1 mA cm⁻¹ voltage. -2 Constant current charge-discharge cycle tests were performed on the current density, and the discharge capacity retention rate was recorded after 50 and 100 cycles, respectively.

[0074] 4. Electrochemical Impedance Spectroscopy (EIS) Testing: EIS testing was performed using an electrochemical workstation (model CHI 760E) at open-circuit potential. The frequency scan range was 0.01 Hz to 100 kHz, and the AC perturbation amplitude was 5 mV. EIS measurements were performed on the full cell before cycling and after the 1st, 10th, 30th, and 50th cycles. The interfacial charge transfer impedance (R0) was then fitted to obtain the impedance. et The value is used to characterize the evolution of the stability of the current collector-electrolyte interface with cycling.

[0075] 5. Symmetrical battery cycle stability test: First, apply 1 mA cm⁻¹ to each current collector. -2 Pre-deposition of 5mAh cm⁻¹ current density -2 The lithium metal transforms the current collector into a lithium anode. A symmetrical cell is constructed by symmetrically assembling two identical pre-deposited lithium current collectors at 1 mA cm⁻¹. -2 At a current density of 1 mAh cm⁻¹ -2 The interface capacity was subjected to constant current charge-discharge cycles, with each half-cycle lasting 30 minutes. The overpotential during charge and discharge was recorded as a function of the number of cycles, and the test was continued for at least 500 hours to evaluate the long-term stability of the interface.

[0076] 6. Rate Performance Testing: Rate testing was conducted using a full-cell configuration. Tests were performed sequentially at 0.5, 1, 2, 3, and 5 mA cm⁻¹. -2 Each circuit was cyclically run for 5 cycles at a current density of 0.5 mA cm⁻¹, then restored to 0.5 mA cm⁻¹. -2The circuit was repeated 5 times to examine the capacity retention and recovery capabilities of the current collector under different current densities.

[0077] IV. Test Results The current collectors prepared in each embodiment and comparative example were evaluated for electrochemical performance according to the unified test method described above. The test results are summarized in Tables 1, 2, and 3, respectively.

[0078] Table 1. Deposition overpotential and full-cell cycle performance of each embodiment and comparative example. Table 2. Overpotential and interface impedance data of symmetrical cells in some embodiments and comparative examples. Table 3 Rate performance (discharge capacity retention, %) of some embodiments and comparative examples Table 4. Coulomb efficiency data for some embodiments and comparative examples. V. Test Result Analysis 1. Overall performance of the preferred solution The deposition overpotential of Example 1 was 7.9 mV, indicating that the Ag nanoparticle array in the lower half of the porous copper mesh can significantly reduce the lithium nucleation barrier and effectively guide lithium ions to uniformly nucleate at the bottom of the current collector. In the full-cell cycle test, Example 1 maintained a capacity retention of 94.28% after 50 cycles and 88.5% after 100 cycles, far superior to all comparative examples. Symmetric cell testing showed that the initial overpotential of Example 1 was only 18.2 mV, and the overpotential only increased to 24.6 mV after 500 h of continuous cycling, with a polarization increase of less than 35%, confirming the ability of the "wrinkled graphene-PDMS" dynamic functional layer to continuously provide ordered deposition space for lithium metal during long-term cycling. EIS data showed that the interfacial charge transfer resistance R of Example 1 after 50 cycles was... et The interface remained highly stable only when the Ω was increased from 12.3 Ω to 15.8 Ω. In the rate test, Example 1 was tested at 5 mA cm⁻¹. -2 It retains 85.8% of its capacity even at high current densities, recovering to 0.5 mA cm⁻¹. -2 The capacity recovery rate reached 97.5%, demonstrating excellent dynamic response capability and structural reversibility. Example 17, as a repeatability verification group of Example 1, showed that all performance indicators (overpotential 8.2 mV, 50-cycle retention rate 93.95%, 100-cycle retention rate 87.8%) were highly consistent with Example 1, confirming the repeatability of this preferred scheme.

[0079] 2. Key Influences of Ag Deposition Location In Example 2, after adjusting the Ag deposition position to the upper half of the copper mesh, the deposition overpotential increased sharply to 37.5 mV, and the capacity retention rate dropped drastically to 65.37% after 50 cycles. When the Ag nanoparticles are located in the upper half, i.e., the direct contact surface with the graphene functional layer, lithium ions are preferentially nucleated in the upper part of the current collector, which contradicts the design concept of the present invention of "bottom-up" layer-by-layer orderly deposition. This preferential deposition in the upper part leads to a mismatch between the lithium layer thickening direction and the wrinkle unfolding direction, preventing the wrinkle structure from being effectively triggered to unfold. While the bottom layer space is underutilized, local stress concentration occurs in the upper layer, accelerating dendrite growth and dead lithium accumulation. This result fully demonstrates that modifying the lower half of the copper mesh with lithium-philic nanoparticles to achieve preferential nucleation guidance at the bottom is a prerequisite for the effective operation of the three-stage dynamic response mechanism of the present invention.

[0080] 3. Influence of Ag nanoparticle size In Example 3, after reducing the Ag particle size to 5–10 nm, the overpotential increased to 25.2 mV, and the capacity retention after 50 cycles decreased to 73.65%. Although smaller Ag particles have a higher number density, the effective nucleation site area provided by a single particle is limited, resulting in a decrease in the charge transfer efficiency between lithium ions and the Ag surface, leading to unfavorable nucleation kinetics. In Examples 9 and 10, the overpotentials were 12.8 mV and 8.6 mV, respectively, and the capacity retention after 50 cycles were 90.15% and 93.42%, respectively, both at good levels. These results indicate that Ag nanoparticles can effectively exert lithiophilic functions within the particle size range of 10–30 nm, with 20–25 nm being the optimal particle size, achieving the best balance between specific surface area and single-particle activity.

[0081] 4. Influence of PVDF anchor point parameters In Example 4, increasing the anchor point spacing to 500 μm reduced the 50-turn capacity retention rate to 85.42%, and further to 76.3% after 100 turns. This indicates that excessively sparse anchor points cannot effectively constrain the deformation of the folded structure, leading to local instability and slippage during repeated expansion and contraction. Example 13 (100 μm spacing, 5 wt% concentration) achieved a 50-turn capacity retention rate of 92.14%. Example 14 (300 μm spacing, 10 wt% concentration) showed a 50-turn capacity retention rate of 91.76%, demonstrating good performance. Overall, a spacing of 200 μm and a concentration of 8 wt% (Example 1) is the optimal combination, achieving the best balance between the fold unfolding freedom and mechanical constraints. However, the performance differences within the 100–300 μm spacing range are not significant, and all can meet practical application requirements.

[0082] 5. Effect of PDMS pre-stretch ratio In Example 5, reducing the pre-stretch ratio to 150% increased the wrinkle wavelength to 12 μm and reduced the amplitude to 2 μm, compared to Example 1 (wavelength 10 μm, amplitude 3 μm), resulting in reduced wrinkle depth and unfoldable space. This directly led to insufficient available expansion space during lithium metal deposition, and increased polarization in the later stages of cycling. The capacity retention rate decreased to 81.26% after 50 cycles and to 71.5% after 100 cycles. Example 17 confirmed the repeatability of the 200% pre-stretch ratio scheme (93.95% retention rate after 50 cycles). The results show that a 200% pre-stretch ratio can provide sufficient wrinkle reserve with an amplitude of approximately 3 μm, ensuring that the dynamic functional layer always has sufficient expansion margin during long-term cycling. Higher pre-stretch ratios within the 150%–200% range result in better performance.

[0083] 6. Influence of graphene film parameters In Example 6, reducing the graphene thickness to 30 nm increased sheet resistance, decreased conductivity, and reduced 50-cycle capacity retention to 87.62%. Insufficient mechanical strength made it prone to breakage during cycling. Examples 11 (100 nm thickness, 900 °C / 1:5 / 20 min) and 12 (45 nm thickness, 1000 °C / 1:15 / 8 min) showed good 50-cycle retention rates of 92.87% and 91.05%, respectively. Example 21 (55 nm thickness, 980 °C / 1:12 / 12 min) achieved a 50-cycle retention rate of 93.15% and a 100-cycle retention rate of 86.8%, performance close to that of Example 1, indicating that excellent graphene quality can be obtained within the CVD condition range (950–980 °C, flow ratio 1:(9–12)). A higher growth temperature (980°C) combined with a moderate carbon source ratio (1:12) results in higher graphene crystallinity and lower sheet resistance (approximately 150 Ω / sq), which is beneficial for improving the conductivity of the dynamic functional layer. A lower carbon source concentration combined with a higher temperature (Example 12) yields thinner graphene with higher crystallinity, while a higher carbon source concentration combined with a lower temperature (Example 11) yields thicker graphene; both methods meet the requirements for conductivity and mechanical properties. In summary, good results can be obtained within the graphene thickness range of 50–100 nm, with greater thickness resulting in better performance.

[0084] 7. Influence of dealloying treatment conditions Example 7, by extending the processing time to 6 hours for compensation, yielded a porous copper mesh with a porosity of approximately 80% and a pore size of 50–120 μm, an overpotential of 10.5 mV, and a capacity retention of 91.36% after 50 cycles. Example 8, requiring only 2 hours, yielded a porous copper mesh with a porosity of approximately 92% and a pore size of 160–200 μm, an overpotential of 9.2 mV, and a capacity retention of 92.58% after 50 cycles. Both examples validated the rationality of the dealloying parameter range, indicating that within the parameter space of 1–2 M HCl, 30–50 °C, and 2–6 hours, a satisfactory porous copper mesh substrate can be obtained through appropriate matching of concentration, temperature, and time.

[0085] 8. The Influence of Lithophile Nanoparticle Type The overpotentials of Examples 18 (Sn) and 19 (ZnO) were 14.6 mV and 18.3 mV, respectively, with 50-cycle capacity retention rates of 88.73% and 86.15%, both significantly better than the comparative examples. Example 22 (In) had an overpotential of 16.5 mV and a 50-cycle capacity retention rate of 87.36%. In can form a Li-In alloy phase with lithium, exhibiting favorable alloying reaction kinetics and good lithiophilic properties. Example 23 (Pb) had an overpotential of 19.8 mV and a 50-cycle capacity retention rate of 85.62%. Pb forms a Li-Pb alloy phase with lithium (such as LiPb, Li3Pb, etc.), effectively reducing the nucleation barrier. Example 24 (Bi) had an overpotential of 17.2 mV and a 50-cycle capacity retention rate of 86.85%. Bi can form a Li3Bi alloy phase with lithium, also exhibiting good lithiophilic properties. The reaction kinetics for the formation of a Li-Ag alloy phase between Ag and lithium are most favorable, thus exhibiting the lowest nucleation overpotential. Sn can form a Li4.4Sn alloy with lithium, and ZnO can be reduced by lithium to a Li-Zn alloy and Li2O, both of which have the ability to reduce the nucleation overpotential. Example 20 (Ag+Sn composite) showed an overpotential of 10.8 mV and a 50-cycle retention rate of 91.52%, with performance between that of pure Ag and pure Sn schemes. These results confirm that the current collector structure of this invention has good applicability to various lithiophilic materials such as Ag, Sn, ZnO, In, Pb, and Bi, with Ag being the optimal choice.

[0086] 9. The Influence of Assembly Heating Conditions The overpotentials of Examples 15 (60℃ / 2h) and 16 (80℃ / 0.5h) were 8.8 mV and 9.1 mV, respectively, and the capacity retention rates after 50 cycles were 93.05% and 92.46%, respectively, both close to those of Example 1 (70℃ / 1h, 94.28%). This result indicates that within the parameter range of 60–80℃ and 0.5–2 h, different temperature-time combinations can achieve effective interfacial contact. Lower temperatures can be compensated for by extending the time, while higher temperatures can be compensated for by shortening the time; both are essentially equivalent in terms of interfacial bonding effect.

[0087] 10. Comparative Analysis Comparative Example 1 showed an overpotential of 46.3 mV and a 50-cycle retention rate of only 43.57%, failing in less than 500 hours during the symmetric cell test. This indicates that the lack of lithiophilic nanoparticles led to completely disordered lithium nucleation and severe dendrite growth. Comparative Example 2 showed a 65.39% retention rate after 50 cycles, also failing prematurely as a symmetric cell. The dynamic functional layer became ineffective after the wrinkled structure debonded. Comparative Example 3, although possessing a complete Ag lithiophilic layer and PVDF anchoring, showed a 50-cycle retention rate of only 79.32%, with the overpotential rising to 52.8 mV after 500 hours. et The Ω increased from 15.6 Ω to 32.8 Ω, an increase of over 110%, confirming that the current collector could not accommodate the volume change of lithium without an expandable wrinkled structure, leading to continuous interface deterioration. Comparative Example 4 had the worst performance indicators (35.82% capacity retention after 50 cycles), serving as the most basic reference baseline. Comparative Example 5 had insufficient effective specific surface area due to its porosity of only about 45%. The overpotential of Comparative Example 6 was 8.5 mV, close to that of Example 1, indicating good initial nucleation performance, but the capacity retention after 50 cycles was only 82.36%, decreasing to 68.2% after 100 cycles. The overpotential of the symmetric cell rose to 56.3 mV after 500 h. et The Ω increased from 14.5 Ω to 38.6 Ω. This result has important comparative significance: Comparative Example 6 demonstrates that while relying solely on the "static lithophile" strategy can improve initial nucleation, it cannot solve the structural failure problem caused by lithium volume expansion during long-term cycling. In contrast, Example 1 of this invention, after introducing a wrinkled graphene dynamic functional layer based on Comparative Example 6, achieved a 100-cycle capacity retention rate of 88.5% from 68.2% to 88.5%, and a 500-hour symmetric cell overpotential reduction from 56.3 mV to 24.6 mV. et The increase rate dropped from 166% to less than 30%, which fully demonstrates the decisive role of the dynamic expansion mechanism in maintaining interface stability.

[0088] 11. Ratio Performance Analysis As can be seen from Table 3, Example 1 was performed at 0.5~5 mA cm⁻¹ -2 It maintains excellent capacity output over a wide current density range. At the highest current density of 5 mA cm⁻¹-2 Under these conditions, Example 1 still maintained 85.8% of its capacity, significantly better than Comparative Example 1 (58.3%), Comparative Example 4 (45.8%), and Comparative Example 6 (76.8%). The capacity was restored to 0.5 mA cm⁻¹. -2 Subsequently, Example 1 showed a capacity recovery rate of 97.5%, confirming that its reversible deformation did not cause permanent damage to the current collector structure. Comparative Example 6 performed reasonably well at low rates, but its capacity decayed significantly at high rates (5 mA cm⁻¹). -2 Only 76.8% (this is because the static current collector accelerates the lithium deposition rate and increases local stress under high current density, while the lack of a dynamic expansion mechanism leads to rapid interface deterioration).

[0089] 13. Coulomb efficiency analysis As shown in Table 4, Example 1 exhibits the best coulombic efficiency performance. The first-cycle coulombic efficiency of Example 1 is 98.6%, the average coulombic efficiency after 50 cycles reaches 99.2%, and the average coulombic efficiencies after 100 and 200 cycles are 98.8% and 98.5%, respectively, demonstrating extremely stable lithium deposition-stripping reversibility. The high stability of the coulombic efficiency confirms that the "wrinkled graphene-PDMS" dynamic functional layer effectively suppresses the formation of dead lithium and the repeated rupture-reconstruction of the SEI film by continuously releasing ordered space, allowing almost complete stripping and recovery of lithium metal deposited in each cycle. The 200-cycle coulombic efficiencies of Examples 22 (In, 96.0%), 23 (Pb, 95.5%), and 24 (Bi, 95.8%) are all significantly better than those of the comparative examples, confirming the effectiveness of lithiophilic materials such as In, Pb, and Bi in the structure of this invention. The average coulombic efficiency of Comparative Example 4 (planar copper foil) after 200 cycles is only 78.6%. Comparative Example 6 (static lithium-loving copper mesh) achieved a coulombic efficiency of 96.8% in the first cycle, but the average coulombic efficiency dropped to 93.5% after 200 cycles, showing a significant degradation trend. This indicates that the static current collector, lacking a dynamic capacity expansion mechanism, gradually experiences irreversible lithium loss due to structural failure during long-term cycling. In contrast, Example 1 maintained a coulombic efficiency of 98.5% after 200 cycles, with a coulombic efficiency degradation rate of less than 0.5%, further confirming the significant advantage of the dynamic current collector of this invention in maintaining the high reversibility of lithium deposition-stripping.

[0090] Based on the above test results, the dynamic lithium metal anode current collector provided by this invention, which is based on a pressure-triggered expandable structure, exhibits significantly better electrochemical performance than the comparative examples. This demonstrates that the organic combination of the bottom lithium-loving nanoparticle array (guided nucleation), the PVDF weakly bonded lattice (controllable anchoring), and the pre-stretched wrinkled graphene functional layer (dynamic expansion) can achieve excellent dynamic response performance, long-term cycling stability, high rate performance, and excellent coulombic efficiency stability of the current collector.

[0091] The above are merely specific embodiments of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention. All other details not described in detail belong to the prior art.

Claims

1. A dynamic lithium metal anode current collector based on a pressure-triggered expandable structure, characterized in that, The current collector has a two-layer composite three-dimensional structure, including a bottom conductive nucleation layer and an upper dynamic functional layer. The bottom conductive nucleation layer is composed of a porous copper skeleton, which is a brass mesh that has undergone selective dealloying treatment. The surface of the lower half of the porous copper skeleton is modified with an array of lithium-loving nanoparticles. The lithium-loving nanoparticles are selected from one or more of Ag, Sn, ZnO, In, Pb, and Bi, and the particle size is 5~50 nm. The upper dynamic functional layer is a wrinkled graphene-PDMS composite layer, which is composed of a periodic wrinkled structure formed by the stress release after the vertically aligned graphene array grown on a NaCl single crystal substrate by chemical vapor deposition is transferred to a PDMS elastomer substrate. The upper dynamic functional layer and the lower conductive nucleation layer are connected by a weak bonding lattice. The weak bonding lattice is formed by PVDF material through lattice electrospinning technology and has multiple micro-expansion channels extending in the vertical direction. The bonding force between the upper dynamic functional layer and the lower conductive nucleation layer is less than the local shear stress threshold generated by lithium deposition. This causes the weak bonding lattice to be locally destroyed when the internal mechanical pressure reaches a preset threshold during lithium deposition. The wrinkled structure unfolds upward along the micro-expansion channel, providing an orderly growth space for lithium metal. Furthermore, the expansion channel can retract during discharge to maintain structural integrity.

2. The dynamic lithium metal anode current collector based on a pressure-triggered expandable structure according to claim 1, characterized in that, The porous copper skeleton has a porosity of 80%~95% and a pore size of 50~200 μm. The lower half of the porous copper skeleton, which accounts for 50%~70% of the total height, is surface-modified with an array of lithium-loving nanoparticles. The brass mesh has a mesh size of 100~300 and a Zn content of 30~40 wt%.

3. The dynamic lithium metal anode current collector based on a pressure-triggered expandable structure according to claim 1, characterized in that, The lithiophilic nanoparticles are Ag nanoparticles with a particle size of 10~30 nm and a coverage density of 1.0×10⁻⁶. 11 ~3.0×10 11 particles / cm 2 ; The graphene array has a thickness of 50~100 nm and an aspect ratio greater than 10. The wavelength of the periodic pleated structure is 5~20 μm and the amplitude is 1~5 μm. The pre-stretch rate of the PDMS elastomer substrate is 150%~200%.

4. The dynamic lithium metal anode current collector based on a pressure-triggered expandable structure according to claim 1, characterized in that, The growth temperature of the chemical vapor deposition method is 900~1000℃, the flow ratio of carbon source to hydrogen is 1:(5~15), the growth time is 8~20 min, and the resistivity of the obtained graphene film is less than 200 Ω / sq.

5. The dynamic lithium metal anode current collector based on a pressure-triggered expandable structure according to claim 1, characterized in that, The concentration of the PVDF solution used in the lattice electrospinning is 5~10 wt%, and the anchoring point spacing is 100~300 μm; the elastic modulus of the upper dynamic functional layer is 1~50 MPa.

6. The dynamic lithium metal anode current collector based on a pressure-triggered expandable structure according to claim 1, characterized in that, The inner wall of the micro-expansion channel is lithiophilic, which is imparted by at least one of surface oxidation treatment, heteroatom doping, or loading a lithiophilic catalyst.

7. The dynamic lithium metal anode current collector based on a pressure-triggered expandable structure according to claim 1, characterized in that, The current collector in the lithium deposition process includes: the first stage is the initial nucleation guidance stage, in which lithium ions are preferentially captured by the lithium-loving nanoparticles in the lower half of the bottom conductive nucleation layer and uniformly nucleated on its surface; the second stage is the pressure-triggered expansion stage, in which as the lithium deposition layer thickens and the internal mechanical pressure accumulates to a preset threshold, the folded structure of the upper dynamic functional layer unfolds upward along the micro-expansion channel; the third stage is the adaptive ordered filling stage, in which the inner wall of the newly opened expansion channel guides lithium metal to orderly fill the newly released space.

8. A method for preparing a dynamic lithium metal anode current collector based on a pressure-triggered expandable structure as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1: Take a brass mesh with a mesh size of 100-300 and selectively dealloy it with a 1-2 M HCl solution at 30-50°C for 2-6 hours to remove the Zn component, obtaining a porous copper mesh with a porosity of 80%-95% and a pore size of 50-200 μm; ultrasonically clean the porous copper mesh sequentially with acetone, ethanol and deionized water for 5-10 min each, then dry it and place it in a magnetron sputtering system. Using sputtering parameters of 100-200 W, Ar gas pressure of 0.3-0.5 Pa and deposition time of 10-30 min, sputter and deposit an array of lithium-affinity nanoparticles with a particle size of 5-50 nm in the lower half of the porous copper mesh, which accounts for 50%-70% of the total height, to obtain the bottom conductive nucleation layer; Step 2: Using chemical vapor deposition on a NaCl single crystal substrate, a vertically aligned graphene array with a thickness of 50-100 nm and an aspect ratio greater than 10 is grown at a growth temperature of 900-1000℃, a carbon source to hydrogen flow rate ratio of 1:(5-15), and a growth time of 8-20 min to obtain a graphene film; the graphene film is then transferred to a PDMS elastomer substrate with a pre-stretch ratio of 150%-200%, and the pre-stretch stress is released to form a periodic pleated structure with a wavelength of 5-20 μm and an amplitude of 1-5 μm; A 5-10 wt% PVDF solution was sprayed at specific nodes of the pleated structure using a dot matrix electrospinning technique with a needle tip spacing of 100-300 μm to form a weakly bonded lattice. After drying, a pleated graphene-PDMS composite layer was obtained. Step 3: Align the wrinkled graphene-PDMS composite layer with the upper half of the bottom conductive nucleation layer, heat it to 60~80℃ in a vacuum or inert atmosphere and hold for 0.5~2 hours to soften the PDMS and enhance the interfacial contact. Then slowly release the tensile stress to allow the composite layer to naturally adhere to the surface of the porous copper mesh. Remove residual PDMS by cleaning with deionized water or ethanol to obtain a double-layer composite three-dimensional dynamic current collector anchored by PVDF lattice.

9. The preparation method according to claim 8, characterized in that, In step one, the lithiophilic nanoparticles are Ag nanoparticles, the sputtering power is 100~200 W, the Ar gas pressure is 0.3~0.5 Pa, the deposition time is 10~30 min, and the resulting Ag nanoparticles have a particle size of 10~30 nm and a coverage density of 1.0×10⁻⁶. 11 ~3.0×10 11 particles / cm 2 .

10. The preparation method according to claim 8, characterized in that, In step two, the carbon source for the chemical vapor deposition method is CH4, the growth temperature is 950~980℃, the flow ratio of carbon source to hydrogen is 1:(9~12), the growth time is 8~15min, and the resistivity of the obtained graphene film is less than 200 Ω / sq.

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