A current collector, a method for preparing the same, and use thereof

Abstract

The present application relates to the technical field of lithium metal battery, in particular to a current collector, a preparation method and application thereof, the current collector comprises a substrate, the surface of the substrate is coated with a coating layer, the coating layer comprises strawberry DNA with cell wall polysaccharide attached; the preparation method comprises the following steps: S1, preparing a second mixed solution containing strawberry DNA; S2, preparing a dry mixture from the second mixed solution; S3, weighing the dry mixture, adding Tris buffer solution, adjusting pH with the Tris buffer solution, and configuring into a third mixed solution; S4, centrifugal rotation of the third mixed solution in a centrifuge, and taking supernatant as a coating solution; S5, dropping the coating solution on the surface of the polished substrate, and baking in an oven to coat the substrate surface, obtaining the current collector; the current collector can not only effectively inhibit lithium dendrite growth and greatly reduce the short circuit risk of lithium metal battery, but also significantly improve the stability and coulomb efficiency of the battery, further improving the performance of the battery.

Description

Technical Field

[0001] This invention relates to the field of lithium metal battery technology, specifically to a current collector, its preparation method, and its applications. Background Technology

[0002] In lithium metal batteries, current collectors are crucial core components. On the one hand, current collectors serve as attachment carriers for the positive and negative electrode active materials (such as ternary materials and lithium iron phosphate for the positive electrode, and graphite and silicon-based materials for the negative electrode), ensuring the stable fixation of the active materials, preventing them from falling off during charging and discharging, and maintaining the integrity of the electrode structure. On the other hand, current collectors are used to uniformly introduce external current into the active materials and collect and output the current generated by the active materials in the electrochemical reaction, reducing the battery's internal resistance and ensuring efficient energy transmission. They are a key intermediary for the conversion of chemical energy into electrical energy.

[0003] The current collectors of lithium metal batteries are usually made of metal materials. In traditional technology, aluminum foil and copper foil are commonly used as current collectors. Aluminum forms a dense oxide film (Al2O3) on its surface at high potentials (3~4.5V), which has good corrosion resistance and is low in cost and light in weight. Copper has excellent chemical stability at low potentials (0~1V), is not easily corroded by electrolytes, and has higher conductivity than aluminum, which can reduce current transmission loss. To improve battery energy density or adapt to new electrode materials, optimizing the structural design of current collectors is an important direction. For example, some existing technologies construct current collectors as 3D porous structures. For instance, Tsinghua University has constructed current collectors as nanoporous structures, which reduces local current density and thus extends cycle life. Another example is surface modification of current collectors. For instance, the University of California, Berkeley has reduced nucleation overpotential by applying a lithiophilic coating (such as Au or ZnO nanoparticles) to the surface of the current collector. Yet another example is the Chinese Academy of Sciences team, which enhances conductivity and homogenizes lithium-ion flow by applying a graphene layer (carbon material) to the surface of the current collector. Furthermore, Chinese patent CN 118198375 A discloses a negative electrode current collector that forms an animal-derived DNA interface layer on the surface of the current collector, which is beneficial for simultaneously improving the coulombic efficiency and cycle performance of negative electrode-free lithium metal batteries.

[0004] Lithium dendrites are dendritic, needle-like, or moss-like crystalline structures formed by the irregular deposition of lithium metal on the negative electrode surface during the charging and discharging process of lithium-ion batteries (especially lithium metal batteries). Their formation is essentially due to the inhomogeneity of the lithium metal deposition process. The growth of lithium dendrites can severely damage battery safety, cycle life, and energy density, and may even lead to catastrophic accidents. For example, when lithium dendrites grow to a certain length, they can pierce the battery's internal separator (used to isolate the positive and negative electrodes, prevent electron conduction but allow lithium to pass through). +The porous membrane directly connects to the positive and negative electrodes, causing an internal short circuit. The short circuit generates a large amount of heat, causing the electrolyte to decompose and release flammable gases. The membrane melts, the electrode materials burn, and ultimately the battery catches fire and explodes. Lithium dendrites are one of the core bottlenecks restricting the commercial application of lithium metal batteries.

[0005] In practical applications, existing current collectors often exhibit varying degrees of tip effect and lithium dendrite formation due to uneven distribution of lithium ions on the surface. For example, current collectors with an animal-derived DNA interface layer, as described in the prior art, still show significant lithium dendrite growth in practical applications. How to more effectively control the growth of lithium dendrites and further improve the safety and performance of lithium metal batteries is an urgent problem to be solved. Summary of the Invention

[0006] The first aspect of this invention is to solve the above-mentioned technical problems by providing a current collector that can effectively suppress the growth of lithium dendrites, which can greatly reduce the risk of battery short circuit caused by lithium dendrite growth, improve safety, and further improve battery performance.

[0007] A current collector includes a substrate with a coating layer on its surface, the coating layer comprising strawberry DNA with attached cell wall polysaccharides. In this design, the substrate surface is coated with a coating layer containing strawberry DNA, which is plant DNA. This design creatively uses strawberry DNA as a functional unit to construct the interface layer of a lithium metal battery. On one hand, strawberry DNA has a high abundance of guanine-cytosine (GC) base pairs. The nitrogen atoms of the GC base pairs can establish biomimetic ion channels through transient Li–N bonds, achieving a spatially uniform distribution of lithium flux and inducing directional deposition of lithium along crystal planes. On the other hand, during the extraction of strawberry DNA, strawberry cell wall polysaccharides (such as cellulose and hemicellulose) physically co-precipitate and entangle with strawberry DNA, forming a viscous substance that is difficult to separate. These cell wall polysaccharide fragments are usually attached to the strawberry DNA, acting as part of the phosphate backbone of the strawberry DNA. Therefore, the extracted strawberry DNA retains strawberry cell wall polysaccharide fragments (such as cellulose and hemicellulose) in its phosphate backbone. After pyrolysis, cellulose can form an interconnected carbon fiber network, which is equivalent to a thin film to effectively inhibit the growth of lithium metal. It can not only mediate dynamic lithium-ion solvation through hydroxyl groups, but also act as a mechanical buffer layer to alleviate the stress caused by electrode volume changes. Through the hydrogen bonding effect and adaptive viscoelastic properties between the cell wall polysaccharide residues in strawberry DNA and metallic lithium, the accumulation of interfacial stress can be synergistically inhibited, thereby effectively inhibiting the growth of lithium dendrites. This can not only greatly reduce the risk of short circuits in lithium metal batteries and improve safety, but also provide a dual-functional solution of "molecular buffering-directional transport" for the dynamic regulation of highly active lithium metal interfaces, and is conducive to further improving battery performance.

[0008] Preferably, the thickness of the coating layer is 700~900nm. When the thickness of the coating layer is less than 700nm, structural failure will occur due to insufficient coating; when the thickness of the coating layer is greater than 900nm, the impedance will increase significantly due to excessive coating.

[0009] Preferably, the substrate is made of copper foil or aluminum foil.

[0010] Preferably, the cell wall polysaccharide comprises cellulose.

[0011] A second aspect of the present invention provides a method for preparing a current collector, comprising the following steps: Step S1, preparing a second mixture containing strawberry DNA and cell wall polysaccharides; Step S2, preparing a dried mixture from the second mixture, the mixture comprising strawberry DNA and cell wall polysaccharides; Step S3, weighing the mixture, adding Tris buffer, adjusting the pH using Tris buffer, and preparing a third mixture; Step S4, centrifuging the third mixture in a centrifuge, and taking the supernatant as a coating solution, the coating solution containing strawberry DNA and cell wall polysaccharides; Step S5, dropping the coating solution onto a polished substrate surface, and baking it in an oven to coat the substrate surface, thereby forming a coating layer on the substrate surface to obtain a current collector.

[0012] The third aspect of this invention addresses the problem of more effectively extracting strawberry DNA. Further, step S1 includes: step S11, preparing strawberry juice using strawberries; step S12, thoroughly mixing dish soap, edible salt, and deionized water to obtain a DNA extraction solution; step S13, mixing the DNA extraction solution with the strawberry juice and allowing it to stand to obtain a first mixture; and step S14, filtering the strawberry residue from the first mixture to obtain a second mixture. In this solution, by thoroughly mixing dish soap, edible salt, and deionized water to obtain the DNA extraction solution, the innovative use of the combination of dish soap and edible salt, through the synergistic effect of ions and non-ions, extracts strawberry DNA. This not only significantly improves the extraction rate of strawberry DNA but also results in the extracted DNA solution containing strawberry cell wall polysaccharide fragments (such as cellulose and hemicellulose), which effectively inhibits the growth of lithium dendrites.

[0013] Preferably, in step S11, a number of fresh strawberries are washed and placed in a plastic bag and crushed to obtain the strawberry juice. By using a plastic bag, it is easier to crush the strawberries inside, and it also prevents the strawberry pulp and juice from leaking out, thereby improving the utilization rate of strawberry DNA.

[0014] Preferably, the detergent used is APG detergent. The hydrophobic alkyl chain of APG detergent breaks down the DNA hydration layer through competitive hydrogen bonding, causing strawberry DNA single strands to penetrate into the micro-gaps of copper grain boundaries. At the same time, with the help of table salt (NaCl), it effectively weakens the repulsive forces between the phosphate groups of strawberry DNA, inducing the strawberry DNA strands to fold into a rigid conformation perpendicular to the copper substrate, thereby helping to inhibit the growth of lithium dendrites and improve battery performance.

[0015] The fourth aspect of this invention addresses the problem of further improving battery performance. Preferably, the ratio of detergent, edible salt, and deionized water in the DNA extraction solution is 10 ml: 1 g: 30 ml. In this solution, by controlling the ratio of detergent to edible salt in the DNA extraction solution to 10 ml: 1 g, the hydrophobic alkyl chain of APG detergent competitively breaks down the DNA hydration layer through hydrogen bonding, causing the strawberry DNA single strand to penetrate into the micro-gap of the copper grain boundaries. Furthermore, by strictly limiting the use of edible salt (NaCl) to produce a Debye shielding effect, the repulsive force between the phosphate groups of the strawberry DNA can be weakened by 75% (the zeta potential increases from -35 mV to -12 mV), inducing the strawberry DNA chain to fold into a rigid conformation perpendicular to the copper substrate. This not only helps to inhibit the growth of lithium dendrites but also improves battery performance.

[0016] Preferably, in step S12, the amount of dishwashing liquid added is 50ml, the amount of edible salt added is 5g, and the amount of deionized water added is 150ml. This is beneficial for further improving battery performance.

[0017] The fifth aspect of this invention addresses the problem of improving the extraction efficiency of strawberry DNA. Further, step S2 includes: step S21, adding alcohol to the second mixture and allowing it to stand, causing the strawberry DNA in the second mixture to dehydrate and coagulate into a flocculent precipitate, wherein the alcohol concentration is greater than or equal to 95%; step S22, separating the flocculent precipitate and rinsing it with alcohol to remove remaining impurities, obtaining a flocculent precipitate; and step S23, heating the flocculent precipitate to obtain a dry mixture, wherein the mixture includes strawberry DNA and cell wall polysaccharides. In this scheme, by adding alcohol with a concentration greater than or equal to 95% to the second mixture, the alcohol causes the strawberry DNA mixed with cell wall polysaccharides in the second mixture to dehydrate and coagulate into a flocculent precipitate, which not only ensures optimal precipitation efficiency but also effectively reduces the dissolution loss of strawberry DNA, thereby significantly improving the extraction efficiency of strawberry DNA. Simultaneously, the phosphate backbone of the strawberry DNA retains strawberry cell wall polysaccharide fragments, which is beneficial for more effectively inhibiting the growth of lithium dendrites.

[0018] Preferably, in step S21, the concentration of alcohol is 95%.

[0019] The sixth aspect of this invention addresses the problem of further improving battery performance. Preferably, in step S21, the volume ratio of alcohol to the second mixture is 2:1 to 4:1. In this solution, when the volume ratio of alcohol to the second mixture is less than 2:1, impurities in the coating solution increase significantly, severely affecting battery performance; when the volume ratio of alcohol to the second mixture is greater than 4:1, the strawberry DNA in the coating solution is broken, which also severely affects battery performance. Therefore, controlling the volume ratio of alcohol to the second mixture to 2:1 to 4:1 can reduce residual impurities and prevent strawberry DNA breakage, thereby effectively improving the quality of the coating solution and achieving the goal of further improving battery performance.

[0020] Preferably, in step S21, the volume ratio of alcohol to the second mixture is 3:1. This simultaneously addresses the issues of residual impurities and strawberry DNA breakage, effectively improving the quality of the coating solution and thus significantly enhancing battery performance.

[0021] To address the issue of rapidly drying the flocculent precipitate without damaging the strawberry DNA, preferably, in step S23, the flocculent precipitate is baked in an oven at a temperature controlled at 50°C. In this solution, controlling the baking temperature to 50°C effectively prevents damage to the strawberry DNA mixed with cell wall polysaccharides and also more efficiently removes alcohol and water, thus achieving the goal of drying the flocculent precipitate.

[0022] Preferably, in step S3, the pH of the third mixture is adjusted to 8.0 using Tris buffer.

[0023] The seventh aspect of this invention addresses the problem of further improving battery performance. Preferably, in step S3, the concentration of strawberry DNA in the third mixture is 7 mg / ml. This concentration represents the maximum saturation level at which DNA can dissolve in the Tris solution. At this concentration, the amount of DNA coated on the copper foil is maximized, which not only significantly improves battery performance but also achieves better suppression of lithium dendrite growth.

[0024] To address the issue of faster drying of the coating layer without damaging the strawberry DNA, preferably, the drying temperature in the oven in step S5 is 50°C. In this solution, by controlling the drying temperature in the oven to 50°C, damage to the strawberry DNA can be effectively prevented, and the coating layer can be dried more efficiently, resulting in a current collector with a strawberry DNA coating layer.

[0025] The eighth aspect of this invention provides the use of the current collector in lithium metal batteries, which is beneficial for further improving battery performance.

[0026] Compared with the prior art, the current collector, its preparation method and application provided by the present invention can not only effectively suppress the growth of lithium dendrites, thereby significantly reducing the short circuit risk of lithium metal batteries caused by lithium dendrite growth and improving safety; but also improve the stability and coulombic efficiency of lithium metal batteries, thereby further improving battery performance. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 To perform 1 mA cm on pure copper -2 3mAh cm -2 Electron micrograph of lithium plating.

[0029] Figure 2 To test the copper foil coated with strawberry DNA at 1 mA cm -2 3mAh cm -2 Electron micrograph of lithium plating.

[0030] Figure 3 For two sets of half-cells at 1mA cm -2 1mAh cm -2 The coulombic efficiency curve under certain cycle conditions is a graph showing the change in coulombic efficiency of the two batteries under long-term cycling.

[0031] Figure 4 The graphs show the coulombic efficiency curves and the specific capacity curves for two sets of full-cell cycles, i.e., the changes in coulombic efficiency and specific capacity of the two types of batteries under long-term cycling.

[0032] Figure 5 To separately perform 1 mA cm-scale analysis on animal DNA coating layers and strawberry DNA coating layers. -2 3mAh cm -2 Microscopic images of lithium dendrites at 30 min, 60 min and 120 min during the lithium plating test. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0034] Example 1

[0035] This embodiment provides a method for preparing a current collector, including the following steps: Step S1, preparing a mixture containing strawberry DNA and cell wall polysaccharides.

[0036] In practice, this step specifically includes step S11: washing several fresh strawberries and placing them in a plastic bag for thorough crushing to obtain strawberry juice (including strawberry pulp and juice). Using a plastic bag facilitates crushing the strawberries and prevents leakage of strawberry pulp and juice, thereby improving the utilization rate of strawberry DNA (i.e., deoxyribonucleic acid). The number of strawberries can be determined according to actual needs; preferably, 3-4 strawberries are used. In this embodiment, 3 strawberries are used. During the thorough crushing process, the strawberry cell walls are disrupted, and strawberry cell wall polysaccharides (such as cellulose and hemicellulose) undergo physical co-precipitation and entanglement with strawberry DNA, forming a viscous substance that is difficult to separate (i.e., mixed together). These cell wall polysaccharide fragments (referred to as cell wall polysaccharides) typically attach to the phosphate backbone of the strawberry DNA, acting as if they were part of the phosphate backbone, and the two are not easily separated.

[0037] Step S12, preparing the DNA extraction solution: Add a certain amount of dish soap, table salt, and deionized water to a beaker and stir thoroughly to obtain the DNA extraction solution. In practice, the amounts of dish soap, table salt, and deionized water can be determined according to actual needs. For example, the amount of dish soap can be 50ml, the amount of table salt 5g, and the amount of deionized water 150ml. Stir all three thoroughly in the beaker to obtain the DNA extraction solution. Using a DNA extraction solution composed of dish soap, table salt, and deionized water can not only effectively extract strawberry DNA from strawberry juice but also avoid damaging the strawberry cell wall polysaccharide fragments mixed (or attached) to the strawberry DNA, ensuring that the cell wall polysaccharide fragments adhere to the strawberry DNA.

[0038] Step S13: Mix the DNA extract with strawberry juice and let it stand to obtain the first mixture. In practice, the DNA extract can be poured directly into a sealed plastic bag, allowing the DNA extract and strawberry juice to come into full contact and stand for a period of time. The standing time can be determined according to actual needs, such as 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, etc. For example, in this embodiment, after mixing the DNA extract with strawberry juice, it is left to stand for 5 minutes.

[0039] Step S14: Filter the strawberry residue from the first mixture to obtain the second mixture, and place the second mixture in a beaker for later use. In practice, the strawberry residue in the first mixture can be filtered out using fine gauze, or alternatively, a wire mesh or filter membrane can be used. It is understood that the obtained second mixture includes strawberry DNA, as well as strawberry cell wall polysaccharide fragments attached to the strawberry DNA.

[0040] Step S2: Prepare a dried mixture from the second mixture, the mixture comprising strawberry DNA with attached cell wall polysaccharides.

[0041] As an example, this embodiment uses alcohol to extract a mixture containing strawberry DNA and cell wall polysaccharides from the second mixture. Specifically, this step includes step S21: adding alcohol to the second mixture and allowing it to stand, causing the strawberry DNA in the second mixture (essentially strawberry DNA with attached cell wall polysaccharides, which will not be described further below) to dehydrate and coagulate into a flocculent precipitate. In practice, alcohol can be directly added to the beaker containing the second mixture. In this step, by adding alcohol to the second mixture, from a molecular perspective, alcohol can cause the strawberry DNA in the second mixture to dehydrate and coagulate into a flocculent precipitate, thus allowing it to be separated from the second mixture. Simultaneously, alcohol can effectively remove lipid compounds from the second mixture, dissolving non-polar impurities and effectively preventing lipid compounds from harming battery performance. Furthermore, alcohol can inhibit the activity of deoxyribonuclease to maintain the integrity of the DNA structure.

[0042] During implementation, the concentration of alcohol can be determined according to actual needs. For example, in this embodiment, the concentration of alcohol is 95%, which is beneficial to achieving the best precipitation efficiency. Correspondingly, the amount of alcohol added can also be determined according to actual needs. For example, in this embodiment, the volume ratio of alcohol to the second mixture can be 3:1, which can effectively reduce impurity residues and prevent strawberry DNA breakage, thus ensuring the integrity of strawberry DNA.

[0043] Step S22: Separate the flocculent precipitate and rinse with alcohol to remove remaining impurities, obtaining a flocculent precipitate. In the beaker, the flocculent precipitate is usually suspended in the upper layer. Therefore, in practice, the suspended flocculent precipitate can be removed with a glass rod to separate it from the liquid, obtaining a flocculent precipitate containing only alcohol and water.

[0044] During rinsing, alcohol is used to rinse the flocculent precipitate. On the one hand, this will not introduce new impurities, and on the other hand, it can remove other impurities attached to the flocculent precipitate through rinsing, thereby achieving the purpose of effectively purifying the flocculent precipitate.

[0045] Step S23: Heat the flocculent precipitate to remove the alcohol and water adhering to it, obtaining dried strawberry DNA. In practice, the flocculent precipitate can be placed in an oven for baking to separate the alcohol and water and dry the precipitate. In other embodiments, a warm water bath can also be used to heat the precipitate, effectively removing alcohol and water, but without removing the attached cell wall polysaccharides. Therefore, heating temperature is a crucial factor. Strawberry DNA is essentially a phosphate-containing organic macromolecule; excessively high temperatures can cause the deoxyribophosphate backbone to break, damaging the strawberry DNA and cell wall polysaccharides, severely affecting the effectiveness of the current collector. Conversely, excessively low temperatures cannot break the bond between water molecules and hydrophilic groups (such as amine groups), hindering the drying of the flocculent precipitate. In industrial applications, drying temperatures are typically 60-120℃. However, preliminary experiments revealed that strawberry DNA breaks down at 60℃. Therefore, to address this technical issue, comparative experiments were conducted to investigate the impact of heating temperature on this step. The experiments showed that when the heating temperature exceeds 52℃, the β-D-2 deoxyribose in strawberry DNA begins to degrade, and the strawberry DNA begins to be damaged. Conversely, when the heating temperature is below 50℃, the binding of water molecules to hydrophilic groups (such as amine groups) is less likely to break down. Above 50℃, the binding of water molecules... The binding with hydrophilic groups (such as amine groups) is more easily broken, indicating that 50°C is the critical point between the activation energy of polymer thermal motion and the hydrolysis energy barrier. Therefore, in practice, the heating temperature of the flocculent precipitate is preferably controlled at 50°C to 51°C, which can effectively prevent the destruction of strawberry DNA and cell wall polysaccharides, and can also remove alcohol and water more efficiently. As an example, in this embodiment, the flocculent precipitate is baked in an oven at a heating temperature of 50°C. Of course, in other embodiments, the heating temperature can also be preferably controlled at 50.5°C, 51°C, etc., which will not be listed here.

[0046] In addition, previous experiments investigated the effect of alcohol concentration on strawberry DNA. The results showed that when the alcohol concentration was 97%, under the same second mixture, the amount of mixture (mainly strawberry DNA) obtained in this step was basically the same as that obtained when the alcohol concentration was 95%. When the alcohol concentration was 90%, the amount of mixture obtained in this step was significantly less than that obtained when the alcohol concentration was 95%. When the alcohol concentration was 85%, the amount of mixture obtained in this step was much less than that obtained when the alcohol concentration was 90%, and only about 60% of that obtained when the alcohol concentration was 95%. The experimental data showed that an alcohol concentration below 85% would cause a strawberry DNA dissolution loss of more than 40%, while a high concentration of 95% alcohol could ensure the best precipitation efficiency.

[0047] Step S3: Weigh the obtained mixture and add Tris buffer to adjust the pH, thus preparing the third mixture. In this step, the Tris buffer will not react with strawberry DNA and cell wall polysaccharides. On the one hand, the main purpose of adding Tris buffer is to adjust the pH of the third mixture and maintain its stability. For example, in this embodiment, the pH of the third mixture is adjusted to 8.0, which can both protect the molecular mechanism of strawberry DNA structural integrity and effectively improve the electrochemical matching degree of the copper foil interface. On the other hand, by mixing strawberry DNA with Tris buffer to form the third mixture, the strawberry DNA molecules can be uniformly dispersed in the solution, which is beneficial for achieving more uniform coating in the subsequent process, thereby improving the performance of the battery.

[0048] In practice, the concentration of strawberry DNA in the third mixture can be determined according to actual needs. For example, in this embodiment, the concentration of strawberry DNA in the third mixture is controlled at 7 mg / ml. According to previous experiments, this concentration is the maximum saturation that allows strawberry DNA to dissolve in the Tris solution. At this concentration, the content of strawberry DNA coated on the copper foil is the largest, and correspondingly, the content of cell wall polysaccharides is also the largest. This not only greatly improves the performance of the battery, but also effectively inhibits the growth of lithium dendrites.

[0049] Step S4: The third mixture is centrifuged in a centrifuge, and the supernatant is used as a coating solution. This coating solution includes strawberry DNA containing cell wall polysaccharides. In practice, a high-speed centrifuge is preferred. During centrifugation, the rotation speed can reach 10,000 rpm to achieve high-speed centrifugation of the third mixture, enabling efficient liquid-solid phase separation and removing impurities. However, this process cannot remove the cell wall polysaccharides attached to the strawberry DNA, thus improving the purity of the strawberry DNA molecules and optimizing the performance of the subsequent battery. The centrifugation time can be determined according to actual needs; in this embodiment, the centrifugation process is 3 minutes.

[0050] The coating solution prepared using the above steps not only contains strawberry DNA, but also contains cell wall polysaccharides attached to the strawberry DNA. Unlike animal DNA, strawberry DNA has a high abundance of guanine-cytosine (GC) base pairs, which can form a dense nitrogen coordination network, giving it a unique lithium-ion affinity. For example, the nitrogen atoms of the GC base pairs can establish biomimetic ion channels through transient Li–N bonds, which can achieve a spatially uniform distribution of lithium flux and induce lithium to be deposited directionally along the crystal plane. At the same time, its phosphate backbone retains strawberry cell wall polysaccharide fragments (such as cellulose and hemicellulose). After pyrolysis of cellulose, it can form a layer of interconnected carbon fiber network, which is equivalent to a thin film to effectively inhibit the growth of lithium dendrites. It can not only mediate dynamic lithium-ion solvation through hydroxyl groups, but also act as a mechanical buffer layer to alleviate the stress of electrode volume change.

[0051] Step S5: The coating liquid is dropped onto the polished substrate surface and baked in an oven to fully coat the substrate surface, so as to form a coating layer on the substrate surface and obtain a current collector; the current collector includes a substrate and a coating layer covering the substrate surface, the coating layer including strawberry DNA mixed with (or attached with) cell wall polysaccharides.

[0052] In practice, the drying temperature inside the oven can be determined according to actual needs. As mentioned earlier, when the temperature is above 52℃, the β-D-2 deoxyribose in strawberry DNA begins to degrade, and the strawberry DNA begins to be damaged. When the temperature is below 50℃, the temperature is too low, and the binding of water molecules with hydrophilic groups (such as amine groups) is not easily broken. When the temperature is above 50℃, the binding of water molecules with hydrophilic groups (such as amine groups) is more easily broken, indicating that 50℃ is the critical point between the activation energy of polymer thermal motion and the hydrolysis energy barrier. Therefore, in this step, the drying temperature inside the oven is preferably controlled at 50℃~51℃, which can effectively prevent the strawberry DNA from being damaged and can dry more efficiently. As an example, in this embodiment, the drying temperature inside the oven is 50℃. Of course, in other embodiments, the drying temperature inside the oven can also be preferably controlled at 50.5℃, 51℃, etc., which will not be listed here.

[0053] In implementation, either copper foil or aluminum foil can be used as the substrate, both of which can achieve efficient current transmission. As an example, in this embodiment, copper foil is used as the substrate.

[0054] During implementation, the thickness of the coating layer can be determined based on the baking time. In practice, the coating layer thickness is precisely controlled by precisely controlling the baking time. After the preset baking time is reached, excess coating liquid is washed off the interface. Furthermore, preliminary experiments have shown that if the coating layer is too thin, insufficient coating can lead to structural failure; conversely, if the coating layer is too thick, a significant increase in impedance will occur. Research has found that when the coating layer thickness is below 700 nm, structural failure occurs due to insufficient coating; and when the coating layer thickness is greater than 900 nm, a significant increase in impedance occurs due to excessive coating. In implementation, the thickness of the coating layer can be preferentially controlled at 700-900 nm. Since the size of strawberry DNA molecules is approximately 2-3 nm (base pair length), a coating layer thickness of 700-900 nm is equivalent to 300-450 layers of DNA molecules stacked on the substrate surface, forming a continuous layered structure. More preferably, the thickness of the coating layer can be preferentially controlled at 750-800 nm. When the coating layer thickness reaches 700-750 nm, the problem of structural failure due to insufficient coating is alleviated, and the impedance of the coating layer is relatively... The impedance of the coating layer is relatively low. When the thickness of the coating layer reaches 750~800nm, structural failure due to insufficient coating is unlikely, and the impedance of the coating layer is relatively low. When the thickness of the coating layer reaches 800~900nm, structural failure due to insufficient coating is unlikely, but the impedance of the coating layer is relatively high. For example, in this embodiment, the thickness of the coating layer can be preferentially controlled to 750nm, 760nm, or 770nm, which can not only improve structural stability and coating success rate, but also effectively control impedance and further improve battery performance.

[0055] For ease of testing, in this embodiment, the prepared current collector is cut into a circular piece with a diameter of 12 mm.

[0056] Comparative Example 1

[0057] A substrate with the same specifications as the substrate in Example 1 was used as the current collector. Since the substrate in Example 1 was copper foil, the current collector in this comparative example was copper foil without a coating layer, which was also cut into a circular piece with a diameter of 12 mm.

[0058] Comparative test: 1. The 12mm diameter disc current collector prepared in Comparative Example 1 was subjected to a 1 mA cm⁻¹ test. -2 3mAhcm -2The lithium plating process was performed, and then the surface of the current collector was observed under an electron microscope, such as... Figure 1 As shown; similarly, the 12mm diameter disc current collector prepared in Example 1 was subjected to 1 mA cm⁻¹ treatment. -2 3mAh cm -2 The lithium plating process was performed, and then the surface of the current collector was observed under an electron microscope, such as... Figure 2 As shown. From Figure 1 As can be seen, lithium dendrite growth is significant in the current collector (i.e., copper foil) after lithium plating; while from... Figure 2 As can be seen, under the same conditions, there is no obvious one-dimensional growth of lithium dendrites, which indicates that the current collector prepared in Example 1 can effectively suppress the growth of lithium dendrites, thereby greatly reducing the risk of short circuit in lithium metal batteries caused by the growth of lithium dendrites.

[0059] 2. Using the 12mm diameter circular current collector prepared in Example 1, a half-cell was assembled to obtain a half-cell that met the testing requirements. Similarly, using the 12mm diameter circular current collector prepared in Comparative Example 1, a half-cell was assembled under the same assembly conditions as the aforementioned half-cell to obtain a half-cell that met the testing requirements. Then, the two sets of half-cells were tested at 1mA cm⁻¹. -2 1mAh cm -2 Under the conditions of charge-discharge cycle experiment, two groups of half-cells were obtained at 1mA cm⁻¹. -2 1mAhcm -2 Coulombic efficiency curves under different charge-discharge cycles are shown in the figure. Figure 3 As shown, from Figure 3 As can be seen, the half-cell composed of the current collector in Comparative Example 1 showed a significant decrease in coulombic efficiency after 50 cycles, while the half-cell composed of the current collector in Example 1 did not show a significant decrease in coulombic efficiency after 350 cycles. This indicates that the current collector prepared in Example 1 can significantly improve the stability and coulombic efficiency of the battery.

[0060] 3. Using the 12mm diameter disc-shaped current collector prepared in Example 1, a full cell was assembled to obtain a full cell that met the testing requirements. Similarly, using the 12mm diameter disc-shaped current collector prepared in Comparative Example 1, a full cell was assembled under the same assembly conditions as the aforementioned full cell to obtain a full cell that met the testing requirements. Then, the two sets of full cells were tested at 1 mA cm⁻¹. -2 1mAh cm -2 Under certain conditions, charge-discharge cycle experiments were conducted on the batteries, and the specific capacity and coulombic efficiency curves of two sets of full cells under different charge-discharge cycles were obtained, as shown in the figure. Figure 4 As shown, from Figure 4As can be seen, the specific capacity of the full cell composed of the current collector in Comparative Example 1 decreased more significantly during cycling than that of the full cell composed of the current collector in Example 1, thus indicating that the current collector prepared in Example 1 can achieve better specific capacity retention and better battery stability.

[0061] Comparative Example 2

[0062] A substrate with the same specifications as the substrate in Example 1 was used as the current collector. Since the substrate in Example 1 was copper foil, in this comparative example, the current collector was a copper foil with a coating layer, which was also cut into a circular piece with a diameter of 12 mm. In this example, the coating layer was a PVDF layer (i.e., polyvinylidene fluoride), and the thickness of the PVDF layer was the same as that of the strawberry DNA in Example 1.

[0063] Comparative Example 3

[0064] A substrate with the same specifications as the substrate in Example 1 was used as the current collector. Since the substrate in Example 1 was copper foil, in this comparative example, the current collector was a copper foil with a coating layer, which was also cut into a circular piece with a diameter of 12 mm. In this embodiment, the coating layer was Al2O3, and the thickness of the coating layer was the same as that of the strawberry DNA in Example 1.

[0065] Comparative test: The current collectors prepared in Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 were subjected to battery charge-discharge cycle experiments under the same conditions. The specific results are shown in Table 1. By comparison, it can be seen that the coulombic efficiency of the current collector prepared in Example 1 decreased the slowest, revealing that the corresponding battery has higher stability and coulombic efficiency.

[0066] Table 1. Results of charge-discharge cycle experiments

[0067]

[0068] Comparative Example 4

[0069] It is understandable that when conducting comparative experiments, several fresh strawberries are first selected, washed, and then placed in a plastic bag and thoroughly crushed to obtain strawberry juice. The strawberry juice is then divided into multiple equal portions, one of which is randomly selected to prepare a current collector in accordance with the method of Example 1. Each comparative example is also selected to prepare a current collector by selecting one portion of strawberry juice. This will not be elaborated further below.

[0070] In this comparative example, a DNA extraction solution was first prepared using 50ml of dish soap, 5g of table salt, and 150ml of deionized water. This DNA extraction solution was then mixed with selected strawberry juice, allowed to fully contact, and allowed to stand for 5 minutes to obtain a first mixture. Strawberry residue was filtered from the first mixture to obtain a second mixture. 95% ethanol was added to the second mixture at a volume ratio of 1:1, causing the strawberry DNA in the second mixture to dehydrate and coagulate, forming a flocculent precipitate. The suspended flocculent precipitate was removed using a glass rod to obtain the flocculent precipitate. Then… The flocculent precipitate was baked in an oven at 50°C to obtain a dry mixture containing strawberry DNA. An equal amount of the strawberry DNA in the mixture was weighed and added to Tris buffer to prepare a third mixture with a concentration of 7 mg / ml. The third mixture was then centrifuged at 10,000 rpm for 3 minutes, and the supernatant was used as the coating solution. Finally, the coating solution was dropped onto the polished substrate surface and dried in an oven at 50°C to fully coat the substrate surface, so as to form a coating layer on the substrate surface, thus obtaining a current collector.

[0071] Comparative Example 5

[0072] In this comparative example, a DNA extraction solution was first prepared using 50 ml of dish soap, 5 g of table salt, and 150 ml of deionized water. This DNA extraction solution was then mixed with selected strawberry juice, allowed to fully contact, and allowed to stand for 5 minutes to obtain a first mixture. Strawberry residue was filtered from the first mixture to obtain a second mixture. 95% ethanol was added to the second mixture at a volume ratio of 2:1, causing the strawberry DNA in the second mixture to dehydrate and coagulate, forming a flocculent precipitate. The suspended flocculent precipitate was removed using a glass rod to obtain a flocculent precipitate. The flocculent precipitate was then baked in an oven at 50°C to obtain dried strawberry DNA. An equal amount of strawberry DNA was weighed and added to Tris buffer to prepare a third mixture with a concentration of 7 mg / ml. The third mixture was then centrifuged at 10,000 rpm for 3 minutes, and the supernatant was used as the coating solution. Finally, the coating solution was dropped onto the polished substrate surface and heated at 50°C. The material is baked in an oven to fully coat the substrate surface, thereby forming a coating layer on the substrate surface and thus obtaining a current collector.

[0073] Comparative Example 6

[0074] In this comparative example, a DNA extraction solution was first prepared using 50 ml of dish soap, 5 g of table salt, and 150 ml of deionized water. This DNA extraction solution was then mixed with selected strawberry juice, allowed to fully contact, and allowed to stand for 5 minutes to obtain a first mixture. Strawberry residue was filtered from the first mixture to obtain a second mixture. 95% ethanol was added to the second mixture at a volume ratio of 4:1, causing the strawberry DNA in the second mixture to dehydrate and coagulate, forming a flocculent precipitate. The suspended flocculent precipitate was removed using a glass rod to obtain the flocculent precipitate. The flocculent precipitate was then dried in an oven at 50°C to obtain a dry mixture. An equal volume of the mixture was weighed and Tris buffer was added to prepare a third mixture with a concentration of 7 mg / ml. The third mixture was then centrifuged at 10,000 rpm for 3 minutes, and the supernatant was taken as the coating solution. Finally, the coating solution was dropped onto the polished substrate surface and dried in an oven at 50°C to fully coat the substrate surface, so as to form a coating layer on the substrate surface and obtain the current collector.

[0075] Comparative Example 7

[0076] In this comparative example, a DNA extraction solution was first prepared using 50ml of dish soap, 5g of table salt, and 150ml of deionized water. This DNA extraction solution was then mixed with selected strawberry juice, allowed to fully contact, and allowed to stand for 5 minutes to obtain a first mixture. Strawberry residue was filtered from the first mixture to obtain a second mixture. 95% ethanol was added to the second mixture at a volume ratio of 5:1, causing the strawberry DNA in the second mixture to dehydrate and coagulate, forming a flocculent precipitate. The suspended flocculent precipitate was removed using a glass rod to obtain a flocculent... The precipitate was then dried in an oven at 50°C to obtain a dry mixture. An equal amount of the mixture was weighed and Tris buffer was added to prepare a third mixture with a concentration of 7 mg / ml. The third mixture was then centrifuged at 10,000 rpm for 3 minutes, and the supernatant was taken as the coating solution. Finally, the coating solution was dropped onto the polished substrate surface and dried in an oven at 50°C to fully coat the substrate surface, so as to form a coating layer on the substrate surface and obtain a current collector.

[0077] Comparative testing: The current collectors prepared in Examples 1, 4, 5, 6, and 7 were assembled into half-cells for performance testing, including at 1 mA cm⁻¹. -2 1mAh cm -2Under the conditions of charge-discharge cycle experiments, the test results showed that: the half-cell corresponding to Example 1 had the highest stability and coulombic efficiency, and the best battery performance; the half-cell corresponding to Comparative Example 4 had much lower stability and coulombic efficiency than the half-cell corresponding to Example 1, and the battery performance was poor; the half-cell corresponding to Comparative Example 5 had lower stability and coulombic efficiency than the half-cell corresponding to Example 1; the half-cell corresponding to Comparative Example 6 had lower stability and coulombic efficiency than the half-cell corresponding to Example 1; and the half-cell corresponding to Comparative Example 7 had much lower stability and coulombic efficiency than the half-cell corresponding to Example 1, and the battery performance was poor. Based on this, the coating solutions obtained during the preparation process were further tested. The tests revealed that the coating solution prepared in Comparative Example 5 contained impurities (the attached strawberry cell wall polysaccharides were not considered impurities). The coating solution prepared in Comparative Example 4 not only contained impurities, but the amount of impurities in Comparative Example 4 increased by about 80% compared to Comparative Example 5, which would seriously affect the battery performance. The coating solution prepared in Comparative Example 5 was comparable to the coating solution prepared in Example 1, with virtually no impurities (excluding strawberry cell wall polysaccharides). However, some strawberry DNA in the coating solution prepared in Comparative Example 5 was broken, and the breakage of strawberry DNA was more pronounced in the coating solution prepared in Comparative Example 7, which seriously affected the battery performance. Therefore, during implementation, when the alcohol concentration is 95%, the volume ratio of alcohol to the second mixture should preferably be controlled at 2:1 to 4:1. This can reduce impurity residue and minimize strawberry DNA breakage. Of course, during implementation, the volume ratio of alcohol to the second mixture can preferably be controlled at 3:1, which can simultaneously solve the problems of impurity residue and strawberry DNA breakage, effectively improve the quality of the coating solution, and thus significantly improve the battery performance.

[0078] Comparative Example 8

[0079] In this comparative example, a DNA extraction solution was first prepared using 50 ml of dish soap, 5 g of table salt, and 150 ml of deionized water. Then, the strawberry DNA extraction solution was mixed with selected strawberry juice, allowed to fully contact, and allowed to stand for 5 minutes to obtain a first mixture. The strawberry residue in the first mixture was filtered out to obtain a second mixture. 95% ethanol was added to the second mixture at a volume ratio of 3:1, causing the strawberry DNA in the second mixture to dehydrate and coagulate, forming a flocculent precipitate. The suspended flocculent precipitate was removed using a glass rod to obtain... Flocculent precipitate was obtained; then the flocculent precipitate was baked in an oven at 50°C to obtain a dry mixture; equal amounts of the mixture were weighed and Tris buffer was added to prepare a third mixture with a concentration of 5 mg / ml; then the third mixture was centrifuged in a centrifuge at 10,000 rpm for 3 minutes, and the supernatant was taken as the coating solution; finally, the coating solution was dropped onto the polished substrate surface and dried in an oven at 50°C to fully coat the substrate surface, so as to form a coating layer on the substrate surface, thus obtaining the current collector.

[0080] Comparative Example 9

[0081] In this comparative example, a DNA extraction solution was first prepared using 50 ml of dish soap, 5 g of table salt, and 150 ml of deionized water. This DNA extraction solution was then mixed with selected strawberry juice, allowed to fully contact, and allowed to stand for 5 minutes to obtain a first mixture. Strawberry residue was filtered from the first mixture to obtain a second mixture. 95% ethanol was added to the second mixture at a volume ratio of 3:1, causing the strawberry DNA in the second mixture to dehydrate and coagulate, forming a flocculent precipitate. The suspended flocculent precipitate was removed using a glass rod to obtain a flocculent precipitate. The flocculent precipitate was then baked in an oven at 50°C to obtain a dry mixture. An equal volume of the mixture was weighed and Tris buffer was added to prepare a third mixture with a concentration of 6 mg / ml. The third mixture was then centrifuged at 10,000 rpm for 3 minutes, and the supernatant was used as the coating solution. Finally, the coating solution was dropped onto the polished substrate surface and heated at 50°C. The material is dried in an oven to fully coat the substrate surface, thus forming a coating layer on the substrate surface to obtain a current collector.

[0082] Comparative testing: The current collectors prepared in Example 1, Comparative Example 8, and Comparative Example 9 were assembled into half-cells for performance testing, including at 1 mA cm⁻¹. -2 1mAh cm -2Under the given conditions, charge-discharge cycle experiments were conducted on the battery. The test results showed that the half-cell corresponding to Example 1 had the highest stability and coulombic efficiency, and the best battery performance. The half-cell corresponding to Comparative Example 8 had lower stability and coulombic efficiency than the half-cell corresponding to Comparative Example 9. The half-cell corresponding to Comparative Example 9 had lower stability and coulombic efficiency than the half-cell corresponding to Example 1. The reason for this is that when the concentration of the third mixture reaches about 7 mg / ml, the strawberry DNA can dissolve to the maximum saturation in the Tris solution. At this concentration, the amount of strawberry DNA contained in the coating solution is the highest, and the amount of strawberry cell wall polysaccharide fragments it carries is also the highest, resulting in the maximum amount of strawberry DNA coated on the matrix, which can significantly improve the battery performance. The amount of strawberry DNA in the coating solution of Comparative Example 9 is relatively small, and the amount of strawberry DNA in the coating solution of Comparative Example 8 is relatively even smaller, which leads to the best performance of the battery prepared in Example 1 and the worst performance of the battery prepared in Comparative Example 8.

[0083] Comparative Example 10

[0084] In this comparative example, 150 ml of deionized water was first used to prepare the DNA extraction solution. Then, the DNA extraction solution was mixed with selected strawberry juice, allowed to fully contact, and allowed to stand for 5 minutes to obtain the first mixture. The strawberry residue in the first mixture was filtered out to obtain the second mixture. 95% ethanol was added to the second mixture at a volume ratio of 3:1, causing the strawberry DNA in the second mixture to dehydrate and coagulate, forming a flocculent precipitate. The suspended flocculent precipitate was removed using a glass rod to obtain the flocculent precipitate. Then, it was dried in an oven. The flocculent precipitate was baked at 50°C to obtain dried strawberry DNA. An equal amount of strawberry DNA was weighed and added to Tris buffer to prepare a third mixture with a concentration of 7 mg / ml. The third mixture was then centrifuged at 10,000 rpm for 3 minutes, and the supernatant was used as the coating solution. Finally, the coating solution was dropped onto the polished substrate surface and dried in a 50°C oven to fully coat the substrate surface, forming a coating layer on the substrate surface, thus obtaining the current collector.

[0085] Comparative Example 11

[0086] In this comparative example, a DNA extraction solution was first prepared using 50 ml of dish soap and 150 ml of deionized water. This DNA extraction solution was then mixed with selected strawberry juice, allowed to fully contact, and allowed to stand for 5 minutes to obtain a first mixture. Strawberry residue was filtered from the first mixture to obtain a second mixture. 95% ethanol was added to the second mixture at a volume ratio of 3:1, causing the strawberry DNA in the second mixture to dehydrate and coagulate, forming a flocculent precipitate. The suspended flocculent precipitate was removed using a glass rod to obtain the flocculent precipitate. The flocculent precipitate was then baked in an oven at 50°C to obtain dried strawberry DNA. An equal amount of strawberry DNA was weighed and added to Tris buffer to prepare a third mixture with a concentration of 7 mg / ml. The third mixture was then centrifuged at 10,000 rpm for 3 minutes, and the supernatant was used as the coating solution. Finally, the coating solution was dropped onto the polished substrate surface and dried in an oven at 50°C to fully coat the substrate surface, so as to form a coating layer on the substrate surface and obtain the current collector.

[0087] Comparative Example 12

[0088] In this comparative example, a DNA extraction solution was first prepared using 5g of table salt and 150ml of deionized water. The DNA extraction solution was then mixed with selected strawberry juice, allowed to fully contact, and allowed to stand for 5 minutes to obtain a first mixture. Strawberry residue in the first mixture was filtered out to obtain a second mixture. 95% ethanol was added to the second mixture at a volume ratio of 3:1, causing the strawberry DNA in the second mixture to dehydrate and coagulate, forming a flocculent precipitate. The suspended flocculent precipitate was removed using a glass rod to obtain the flocculent precipitate. The flocculent precipitate was then baked in an oven at 50°C to obtain dried strawberry DNA. An equal amount of strawberry DNA was weighed and added to Tris buffer to prepare a third mixture with a concentration of 7 mg / ml. The third mixture was then centrifuged at 10,000 rpm for 3 minutes, and the supernatant was used as the coating solution. Finally, the coating solution was dropped onto the polished substrate surface and dried in an oven at 50°C to fully coat the substrate surface, so as to form a coating layer on the substrate surface and obtain the current collector.

[0089] Comparative testing: The current collectors prepared in Example 1, Comparative Example 10, Comparative Example 11, and Comparative Example 12 were assembled into half-cells for performance testing, including at 1 mA cm⁻¹. -2 1mAh cm -2Under the conditions of charge-discharge cycle experiments, the test results showed that the half-cell prepared in Example 1 had the highest stability and coulombic efficiency, and the best battery performance; the stability and coulombic efficiency of the half-cell prepared in Comparative Example 10 were much lower than those of the half-cell prepared in Example 1; the stability and coulombic efficiency of the half-cell prepared in Comparative Example 11 were also much lower than those of the half-cell prepared in Example 1. This is because strawberry DNA is difficult to disperse in solution due to molecular entanglement and electrostatic repulsion of phosphate groups. It is difficult to effectively extract strawberry DNA by simply adding detergent to the strawberry DNA extraction solution, and it is also difficult to effectively extract strawberry DNA by simply adding edible salt to the DNA extraction solution. In Example 1, an innovative method was used... The combined use of food-grade alkyl glycosides (APG detergent, a surfactant) and edible salt (NaCl) to overcome this bottleneck through the synergistic effect of ionic and nonionic compounds significantly improves the extraction rate of strawberry DNA. As shown in Table 2, the extraction rates of strawberry DNA extracts from Examples 1, 10, 11, and 12 were tested. The DNA extract used in Example 1 showed the highest extraction rate and the best fragmentation. The hydrophobic alkyl chain of the APG surfactant breaks down the DNA hydration layer through competitive hydrogen bonding, promoting the penetration of strawberry DNA single strands into the micro-gap of copper grain boundaries. At the same time, NaCl at a strictly limited concentration (e.g., 0.65 mol / L, which achieves the highest balance between DNA purity and yield, exceeding this concentration will lead to polysaccharide co-precipitation) generates a Debye shielding effect, weakening the repulsive force between phosphate groups of strawberry DNA by 75% (increasing the zeta potential from -35 mV to -12 mV), inducing the strawberry DNA chain to fold into a rigid conformation perpendicular to the copper substrate. This not only helps to inhibit the growth of lithium dendrites but also improves battery performance.

[0090] Table 2

[0091]

[0092] Comparative Example 13

[0093] In nature, deoxyribonucleic acid (DNA), with its programmable double helix structure and multidimensional chemical activity, provides a natural template for biomimetic interface design. Unlike animal DNA, the high abundance of guanine-cytosine (GC) base pairs in plant DNA can form a dense nitrogen coordination network, endowing it with unique lithium-ion affinity. Simultaneously, the plant cell wall polysaccharide fragments (such as cellulose and hemicellulose) retained in its phosphate backbone can not only mediate dynamic lithium-ion solvation through hydroxyl groups but also act as a mechanical buffer layer to alleviate stress caused by electrode volume changes. Based on this, this application proposes for the first time to construct a lithium metal battery interface layer using strawberry DNA as a functional unit. Its core scientific value lies in two aspects: firstly, the nitrogen atoms of the GC base pairs establish biomimetic ion channels through transient Li–N bonds, enabling a spatially uniform distribution of lithium flux and inducing directional lithium deposition along crystal planes; secondly, the hydrogen bonding effect and adaptive viscoelastic properties between plant polysaccharide residues and metallic lithium can synergistically suppress interfacial stress accumulation, effectively inhibiting lithium dendrite growth, and providing a dual-functional solution of "molecular buffering-directional transport" for highly active lithium metal interface dynamic regulation.

[0094] In this embodiment, an animal DNA coating layer (using the animal DNA coating layer disclosed in Chinese Patent CN 118198375A) is formed on the outer surface of the substrate to create a current collector coated with the animal DNA coating layer; the thickness of the animal DNA coating layer is the same as the thickness of the coating layer in Example 1. Then, the current collector prepared in Example 1 and the current collector prepared in Comparative Example 13 are subjected to lithium plating tests at 1 mA cm⁻² and 3 mAh cm⁻², respectively. The results are as follows... Figure 5 As shown: Figure 5 The image above the middle arrow shows the test results for the DNA coating layer of the animals in Comparative Example 13. Figure 5 The image below the middle arrow shows the test of the strawberry DNA coating layer in Example 1; from Figure 5 As can be clearly seen, after 2 hours of lithium plating testing, the animal DNA coating layer showed significant lithium dendrite growth, while the lithium ion distribution on the strawberry DNA coating layer remained very uniform, with no obvious lithium dendrites observed. This is mainly due to the plant cell wall polysaccharide fragments attached to the strawberry phosphate backbone. These cell wall polysaccharide fragments include cellulose and hemicellulose, components unique to plant cells and not found in animal cells. After the pyrolysis of plant cellulose, an interconnected carbon fiber network is formed, which is equivalent to setting a thin film to effectively inhibit the growth of lithium metal, thereby achieving the purpose of inhibiting lithium dendrite growth. This not only greatly reduces the risk of short circuits in lithium metal batteries and improves safety, but also helps to further improve battery performance.

[0095] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A current collector, characterized in that, It includes a matrix, the surface of which is covered with a coating layer, the coating layer including strawberry DNA with attached cell wall polysaccharides.

2. The current collector according to claim 1, characterized in that, The coating layer has a thickness of 700-900 nm; the substrate is made of copper foil or aluminum foil; the cell wall polysaccharide includes cellulose.

3. A method for preparing the current collector as described in claim 1, characterized in that, Includes the following steps: Step S1: Prepare a second mixture containing strawberry DNA and cell wall polysaccharides; Step S2: Prepare a dried mixture from the second mixture, the mixture comprising strawberry DNA and cell wall polysaccharides; Step S3: Weigh the dried mixture, add Tris buffer, adjust the pH using Tris buffer, and prepare the third mixture. Step S4: Place the third mixture in a centrifuge and centrifuge, and take the supernatant as the coating solution. The coating solution contains strawberry DNA and cell wall polysaccharides. Step S5: The coating liquid is dropped onto the polished substrate surface and baked in an oven to coat the substrate surface, thereby forming a coating layer on the substrate surface and obtaining a current collector.

4. The preparation method according to claim 3, characterized in that, Step S1 includes step S11, making strawberry juice using strawberries; Step S12: Mix dish soap, table salt and deionized water thoroughly to obtain DNA extraction solution; Step S13: Mix the DNA extract with strawberry juice and let it stand to obtain the first mixture; Step S14: Filter the strawberry residue in the first mixture to obtain the second mixture.

5. The preparation method according to claim 4, characterized in that, The dishwashing liquid used is APG dishwashing liquid.

6. The preparation method according to claim 4, characterized in that, The ratio of detergent, edible salt, and deionized water in the DNA extraction solution is 10ml:1g:30ml.

7. The preparation method according to claim 3, characterized in that, Step S2 includes step S21, adding alcohol to the second mixture and letting it stand, so that the strawberry DNA in the second mixture dehydrates and coagulates to form a flocculent precipitate, wherein the concentration of alcohol is greater than or equal to 95%; Step S22: Separate the flocculent precipitate and wash it with alcohol to remove the remaining impurities, thereby obtaining the flocculent precipitate; Step S23: Heat the flocculent precipitate to obtain a dry mixture.

8. The preparation method according to claim 7, characterized in that, In step S21, the volume ratio of alcohol to the second mixture is 2:1 to 4:

1.

9. The preparation method according to claim 8, characterized in that, In step S21, the concentration of alcohol is 95%; the volume ratio of alcohol to the second mixture is 3:

1.

10. Use of a current collector as described in claim 1 in a lithium metal battery.

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