Current collector based on DNA composite material coating and preparation method and application thereof

Abstract

The invention relates to a current collector based on DNA composite material coating and a preparation method and application thereof, and belongs to the technical field of electrochemical energy storage. The preparation method of the current collector provided by the invention comprises the following steps: (1) cutting okra, removing seeds, adding the okra into water, standing at 0-10 DEG C for 24-36 hours, adding enzymatic hydrolysate for reaction, and performing solid-liquid separation to obtain an extracting solution; (2) adding an ethanol solution into the extracting solution for precipitation, separating to obtain a DNA-containing compound, and uniformly mixing the DNA-containing compound and melamine in a solvent to obtain a mixed solution; and (3) covering the surface of a copper current collector with the mixed solution, standing, and drying to form a coating layer, thereby obtaining the current collector coated on the basis of the DNA composite material. The current collector provided by the invention can improve the specific capacity retention ratio of the battery, so that the battery has better stability.

Description

Technical Field

[0001] This invention relates to the field of electrochemical energy storage technology, and in particular to a current collector based on DNA composite material coating, its preparation method and application. Background Technology

[0002] Copper, with its high conductivity, chemical inertness, and low cost, has become an ideal substrate for lithium metal deposition. It directly influences battery performance by regulating lithium nucleation and growth behavior, while lithium metal itself possesses ultra-high theoretical capacity and extremely low electrochemical potential, significantly improving the energy density of full-cell batteries. Currently, the optimization of copper current collector applications mainly revolves around three major directions: interface engineering optimization, which improves interface stability and ion conduction by constructing inorganic, organic / polymer, or composite artificial SEI layers, and designing high-concentration and locally high-concentration electrolytes and solid electrolytes; structural design, which uses 3D porous copper (such as nanoporous copper and copper nanowire arrays) to reduce local current density and provide directional deposition channels, and homogenizes lithium-ion flow through surface modification methods such as lithiophilic coatings and carbon material composites; and pressure regulation to improve interfacial contact, using in-situ characterization techniques such as cryo-electron microscopy and X-ray tomography to observe lithium deposition and SEI layer evolution. Several technologies have already achieved improvements in cycle performance.

[0003] Currently, copper current collectors still have significant drawbacks in application, with the core issues concentrated in the copper substrate itself: First, the uneven distribution of lithium ions on the uncoated copper surface easily leads to the tip effect, which in turn causes lithium dendrite formation. This not only affects the stability of battery performance but may also pose safety hazards. Second, batteries assembled based on uncoated copper have poor cycle performance and low coulombic efficiency, making it difficult to meet the requirements of high-energy-density batteries for long cycle life and high reversibility. Third, the poor affinity between the untreated copper surface and the electrolyte further exacerbates the unevenness of lithium deposition, creating a vicious cycle of performance degradation.

[0004] Therefore, there is an urgent need to develop a surface coating treatment method for copper current collectors to ensure uniform lithium deposition on the surface, avoid lithium dendrite formation, improve cycle coulombic efficiency, and comprehensively enhance the application performance of copper current collectors. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a current collector based on DNA composite material coating, its preparation method, and its application. The current collector based on DNA composite material coating provided by this invention can form a dense and uniform lithium deposition layer on its surface, further avoiding lithium dendrite formation and improving the stability of electrochemical energy storage devices.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a method for preparing a current collector based on DNA composite material coating, comprising the following steps: (1) Cut the okra and remove the seeds, then add it to water and place it at 0-10℃ for 24-36 h. Then add the enzyme hydrolysate to react and separate the solid and liquid to obtain the extract. The enzymatic hydrolysate includes β-glucanase and alginate lyase; (2) Add ethanol solution to the extract to precipitate and separate the DNA-containing complex. Mix the DNA-containing complex and melamine in a solvent to obtain a mixed solution. (3) The mixed solution is applied to the surface of the copper current collector, and after standing, it is dried to form a coating layer, thus obtaining the current collector based on the DNA composite material coating.

[0007] The technical solution of this application involves extracting an okra DNA complex using specific steps, then combining it with melamine to coat the current collector. The okra used as the extraction raw material is the tender pod of the okra plant (Abelmoschus mandshurica), the edible part of the okra, harvested approximately 4-7 days after flowering, and is bright green in color. Compared to other plant DNA, the DNA in okra mucilage has a high molecular weight and high degree of polymerization, forming a denser, continuous network film after coating the current collector, effectively homogenizing the lithium-ion flow and reducing the risk of lithium dendrite formation. The okra DNA forms a natural DNA-polysaccharide complex with mucilage polysaccharides (pectin, galactomannan, etc.), possessing a multi-hydroxyl structure, enhancing hydrophilicity and wettability with the electrolyte, while also improving the metal chelating ability of the DNA, increasing copper binding sites, and enhancing interfacial stability.

[0008] This application involves cutting okra into small pieces and removing the seeds to facilitate thorough extraction. The okra is first placed under refrigeration for a certain period, allowing the DNA and mucilage polysaccharides in the okra mucilage to slowly dissolve in water. This protects the integrity of the natural DNA-polysaccharide complex in okra, maintains the long-chain DNA structure (>20kbp), and prevents mechanical breakage that could lead to voids in the coating layer. β-glucanase and alginate lyase are then added to target and degrade cell wall polysaccharides, selectively releasing the DNA-polysaccharide complex without damaging phosphodiester bonds or the mucilage polysaccharide structure. The resulting extract contains a relatively intact DNA-polysaccharide complex with high-density polar groups (-OH / -PO4), ensuring lithium affinity.

[0009] Adding an ethanol solution causes the DNA and mucopolysaccharide complex to undergo gradient dehydration and co-precipitate into a three-dimensional network, forming flocculent matter and improving film flexibility. This application further introduces melamine (MEL) into the DNA-polysaccharide complex: on the one hand, the triazine ring of MEL and the phosphate groups of DNA can form a hydrogen bond network, improving the mechanical strength of the coating layer and inhibiting lithium deposition stress cracking; on the other hand, the nitrogen-rich structure of MEL provides negatively charged adsorption sites, homogenizing lithium ion flow and eliminating the tip effect; and MEL's decomposition temperature is >300℃, which can enhance the high-temperature resistance of the coating and improve the stability of the coating layer during high-temperature cycling (such as fast charging). The DNA-MEL interface can also form fast ion channels, improving current performance. Without MEL, problems such as delayed electrolyte wetting, increased interfacial side reactions, and decreased mechanical strength may occur.

[0010] The DNA composite material-coated current collector provided by this invention can improve the mechanical strength of the current collector, enhance the suppression of lithium deposition expansion, homogenize the lithium ion flow, eliminate the tip effect, improve the interface performance, and deposit a dense and uniform lithium coating on the surface, which is beneficial for suppressing dendrite growth, reducing side reactions, stabilizing the electrode structure, improving electrochemical stability, and reducing degradation.

[0011] Preferably, in step (1), the volume ratio of okra to water is 1:(1.5-2.5). More preferably, in step (1), the volume ratio of okra to water is 1:2.

[0012] Preferably, in step (1), the volume ratio of water to enzymatic hydrolysate is 1:(1.2-1.6). More preferably, in step (1), the volume ratio of water to enzymatic hydrolysate is 1:1.4.

[0013] Preferably, in step (1), after adding water to the okra, the treatment condition is to place it at 4°C for 24 hours.

[0014] Preferably, in the enzymatic hydrolysate of step (1), the mass-volume content of β-glucanase is 1.5-2.5%, and the mass-volume content of alginate lyase is 0.2-0.8%. More preferably, in the enzymatic hydrolysate of step (1), the mass-volume content of β-glucanase is 2%, and the mass-volume content of alginate lyase is 0.5%.

[0015] More preferably, in step (1), the reaction time for adding the enzymatic hydrolysate is 8-12 min.

[0016] Preferably, in step (2), the volume ratio of ethanol in the ethanol solution is 95%.

[0017] Preferably, in step (2), the volume ratio of the extract to the ethanol solution is 1:(1-2). More preferably, in step (2), the volume ratio of the extract to the ethanol solution is 1:1.5.

[0018] Preferably, in step (2), the precipitation time is 4-6 min.

[0019] Preferably, in step (2), after obtaining the DNA-containing complex, a drying process is performed, wherein the drying is performed at room temperature for 20-30 h.

[0020] Preferably, in step (2), the mass ratio of the DNA-containing complex to melamine is (1-2):1; Preferably, in step (2), the mass ratio of the DNA-containing complex to melamine is one or any two of the following: 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2.

[0021] More preferably, in step (2), the mass ratio of the DNA-containing complex to melamine is 1:1.5. When the mass ratio of the DNA-containing complex to MEL is 1:1.5, electrode polarization can be avoided; and at this ratio, the three-dimensional network has higher density, which can reduce the exposed area of ​​copper foil and achieve better coating effect.

[0022] Preferably, in the mixed solution of step (2), the total mass-volume concentration of the DNA-containing complex and melamine is 3-5 mg / ml.

[0023] Preferably, in the mixed solution of step (2), the total mass-volume concentration of the DNA-containing complex and melamine is one or any two of the following values: 3 mg / ml, 3.5 mg / ml, 4 mg / ml, 4.5 mg / ml, and 5 mg / ml.

[0024] Preferably, in step (2), the solvent is Tris buffer, the pH of which is 8.3-8.7 and the concentration is 20-35 mmol / L.

[0025] More preferably, in step (2), the solvent is Tris buffer, the pH of the Tris buffer is 8.5, and the concentration is 30 mmol / L.

[0026] Tris buffer refers to the buffer solution of the tris(hydroxymethyl)aminomethane-hydrochloric acid buffer system.

[0027] Secondly, the present invention provides a current collector based on DNA composite material coated by the above-mentioned method for preparing a current collector based on DNA composite material coating.

[0028] Thirdly, the present invention provides the application of the above-mentioned current collector based on DNA composite material coating in electrochemical energy storage devices.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) By optimizing the extraction method, the integrity of the natural DNA-polysaccharide complex in okra is protected and the long chain structure is maintained, which is conducive to the formation of a dense three-dimensional network and avoids the exposure of copper foil caused by mechanical breakage; (2) Based on the DNA-polysaccharide complex, melamine is further introduced to comprehensively improve the mechanical strength of the coating layer, homogenize the lithium ion flow, eliminate the tip effect, and improve the interface performance. The lithium plating results in a dense and highly uniform lithium deposition layer, which is beneficial to improving electrochemical stability. (3) By adjusting the appropriate mass ratio of DNA-polysaccharide complex (DNA-containing complex) to melamine and the concentration of the mixed solution, the density of the three-dimensional network structure formed by the coating layer is increased, thereby comprehensively improving the application performance. Attached Figure Description

[0030] Figure 1 a) SEM image of the surface of pure copper foil in Comparative Example 1; b) SEM image of the surface of the current collector based on DNA composite material in Example 1; c) SEM image of the pure copper foil in Comparative Example 1 after lithium plating; d) SEM image of the surface of the current collector based on DNA composite material in Example 1 after lithium plating. Figure 2 The graph shows the cyclic coulombic efficiency test results of the current collectors assembled into half-cells in Example 1 and Comparative Example 1. Figure 3 This is a graph showing the cycle specific capacity test results of the full cell assembled with current collectors in Example 1; Figure 4 The graph shows the cycle specific capacity test results of the full cell assembled with the current collector in Comparative Example 1. Detailed Implementation

[0031] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available reagents and materials.

[0032] The enzyme sources used in the following examples and comparative examples are as follows: β-glucanase: D888657, purchased from Shanghai Maclean's Biological Reagents; Alginate lyase: PA93791, purchased from Guangdong Wenglong Chemical Reagent; Pectinase Y-23, purchased from Shanghai Maclean's Biological Reagent.

[0033] Example 1 This invention provides an embodiment of a method for preparing a current collector based on DNA composite material coating. The method described in this embodiment is as follows: (1) Purchase okra (the tender pods of coffee okra) from JD.com e-commerce platform, wash it, cut it into pieces about 3cm*3cm*3cm in size and remove the seeds, put it in a bottle with 2 times the volume of deionized water, and refrigerate it at 4℃ for 24 hours before taking it out. The enzyme hydrolysate was prepared by adding β-glucanase and alginate lyase to 1 mM EDTA phosphate buffer, wherein the mass-volume content of β-glucanase was 2% and the mass-volume content of alginate lyase was 0.5%. Add the enzymatic hydrolysate to the refrigerated sample solution (volume ratio of deionized water to enzymatic hydrolysate = 1:1.4), let stand for 10 min, then filter to remove the residue to obtain the extract.

[0034] (2) Add 95% ethanol solution to the obtained extract (the volume ratio of extract to ethanol solution is 1:1.5). After standing for 5 min, use a glass rod to pick out the flocculent material on the upper layer, which is a DNA complex containing okra DNA and mucopolysaccharide. The DNA-containing complex was placed in a petri dish and dried in a constant temperature oven at 25 °C for 24 h. Melamine (MEL) powder was weighed and mixed with the dried DNA-containing complex at a mass ratio of 1.5:1 to obtain DNA@MEL. Tris buffer (Tris-HCl system) with a pH of 8.5 and a concentration of 30 mmol / L was added to prepare a mixed solution with a mass volume concentration of 4 mg / ml for DNA@MEL.

[0035] (3) Prepare a copper foil with a size of 10 cm*10 cm, polish it to remove the surface oxide layer, and then fully immerse it in the prepared DNA@MEL mixed solution. Let it stand for 20 minutes to allow the DNA-mucopolysaccharide-MEL in the mixed solution to fully coat the surface. Take it out, gently wash away the excess unreacted solution on the surface with deionized water, and dry it in a constant temperature oven at 25 ℃ to obtain the current collector based on the DNA composite material coating.

[0036] Example 2 The only difference between Example 2 and Example 1 is that the mass ratio of MEL powder to the dried DNA-containing complex in step (2) is changed to 2:1.

[0037] Example 3 The only difference between Example 3 and Example 1 is that the mass ratio of MEL powder to the dried DNA-containing complex in step (2) is changed to 1:1.

[0038] Example 4 The only difference between Example 4 and Example 1 is that the amount of DNA@MEL added in step (2) is changed to prepare a mixed solution with a DNA@MEL mass-volume concentration of 3 mg / ml.

[0039] Example 5 The only difference between Example 5 and Example 1 is that the amount of DNA@MEL added in step (2) is changed to prepare a mixed solution with a DNA@MEL mass-volume concentration of 5 mg / ml.

[0040] Comparative Example 1 The current collector in Comparative Example 1 is the same copper foil as in step (3) of Example 1, but without the coating treatment.

[0041] Comparative Example 2 The only difference between Comparative Example 2 and Example 1 is that the extraction raw material in step (1) is replaced with potato tubers purchased from the JD.com e-commerce platform. After removing the skin, an appropriate amount is chopped and extracted to prepare the corresponding current collector.

[0042] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the extraction raw material was replaced with spinach leaves purchased from the JD.com e-commerce platform. After a suitable amount was chopped, DNA was extracted using the traditional CTAB method, as detailed below: (1) Take fresh spinach leaves, cut them into small pieces, put them into a mortar, pour in an appropriate amount of liquid nitrogen, and grind them into powder after the leaves are completely frozen. Add the powder to a centrifuge tube containing CTAB extraction buffer and mix well. Place the tube in a 65℃ constant temperature water bath for 60 min, inverting the centrifuge tube 1-2 times every 10-15 min during the process, and let it stand at room temperature for 5 min. The mass-volume ratio of spinach leaves to CTAB buffer should be controlled at about 1 g: 8 mL. (2) Add an equal volume of chloroform-isoamyl alcohol mixture to the centrifuge tube, invert the centrifuge tube 10-20 times, let it stand at room temperature for 10 min, and centrifuge at 4℃ and 12000 rpm for 15 min; after centrifugation, the solution is divided into three layers. Take the upper aqueous phase, avoid mixing with the middle and lower organic phases, and transfer it to a new centrifuge tube. (3) Add an equal volume of pre-cooled isopropanol to the aqueous phase, invert the centrifuge tube 5-10 times until a white flocculent precipitate appears, place it at -20℃ and let it stand for 2 h, centrifuge at 4℃ and 12000 rpm for 10 min to obtain DNA-containing active substances, add 70% ethanol to wash, let stand, centrifuge, wash twice in total, remove the supernatant, and air dry at room temperature to obtain DNA-containing active substance powder.

[0043] Following the same formulation and coating process as the MEL solution prepared in steps (2) and (3), the corresponding current collector is obtained.

[0044] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that commercially available salmon DNA was used. The solution was prepared with MEL according to the ratio and concentration in steps (2) and (3) and then coated to obtain the corresponding current collector.

[0045] Comparative Example 5 The only difference between Comparative Example 5 and Example 1 is that, after adding water in step (1), the enzyme hydrolysate was directly added at room temperature to prepare the corresponding current collector.

[0046] Comparative Example 6 The only difference between Comparative Example 6 and Example 1 is that MEL is not added in step (2), but a mixed solution with a concentration of 4 mg / ml is prepared using a DNA-containing complex to obtain the corresponding current collector.

[0047] Comparative Example 7 The only difference between Comparative Example 7 and Example 1 is that the β-glucanase used in step (1) was replaced with the same amount of pectinase.

[0048] Example of effect To investigate the application performance of the DNA composite material-coated current collector provided by this invention and the effectiveness of its preparation method, the following tests were conducted: (a) Current collector related tests 1. Contact angle of the current collector surface: The contact angle is measured using an optical contact angle meter and calculated using analysis software; 2. Elastic modulus of current collector: Refer to the test method in GB / T 22315; 3. Current collector surface coating condition: SEM was used to observe and analyze the surface morphology of the coating layer after coating to determine whether there are any voids in the coating layer that would expose the copper foil.

[0049] (II) Application performance test of current collector 1. Lithium plating: Lithium was plated on the surface of the current collector in the examples and comparative examples respectively, with a current density of 1 mA·cm. -2The surface capacity is 3mAh·cm³. -2 The surface morphology of the current collector after lithium plating was analyzed using SEM. 2. Half-cell assembly: Current collectors: The current collectors used in the above embodiments and comparative examples are used respectively; Electrolyte: Lithium-sulfur electrolyte; Counter electrode: Lithium metal sheet; Membrane: Celgard 2325 (PP / PE / PP three-layer); Battery casing: CR2032 button battery casing; Assembly sequence: negative electrode shell, lithium sheet, electrolyte (40μL), separator, electrolyte (40μL), working electrode, gasket, spring sheet, positive electrode shell.

[0050] 3. Full battery assembly: Negative electrode: The current collector used is the same as that used in the above embodiments and comparative examples; Positive electrode: The active material layer mass ratio of active material LiCoO2: conductive agent Super P: binder PVDF = 8:1:1 is coated on aluminum foil to obtain the positive electrode; Electrolyte: Lithium hexafluorophosphate (LiPF6); Membrane: Celgard 2325 (PP / PE / PP three-layer); Battery casing: CR2032 button battery casing; 4. Cyclic test conditions: The test step parameters are shown in Table 1 below.

[0051] Table 1. Parameters for Cyclic Test Steps The coulombic efficiency of the prepared half-cell at 150 cycles and the specific capacity of the prepared full cell at 5, 30, 50, 100 and 120 cycles were tested under the above cycling conditions.

[0052] The test results are shown in Table 2 and Figure 1-4 .

[0053] Table 2 shows the test results of the current collector performance in the examples and comparative examples. The test results show that: Compared to the comparative example, the current collector surface coated with DNA composite material provided in this embodiment of the invention has a smaller contact angle and stronger hydrophilicity, which is beneficial for electrolyte wetting, improving interface stability, and suppressing side reactions; at the same time, it has a higher elastic modulus and better mechanical properties, which is beneficial for suppressing lithium deposition volume expansion. Scanning electron microscopy (SEM) observation of the morphology of the copper foil surface in Comparative Example 1 is as follows... Figure 1- (a) It can be seen that the surface of the untreated copper foil is smooth; the morphology of the surface coating layer of the current collector based on DNA composite material prepared in Example 1 is observed by scanning electron microscopy (SEM) as follows. Figure 1 -(b) It can be seen that a relatively dense and uniform coating film has formed on the surface of the current collector, and no voids in the coating layer or exposed copper foil were observed. The surface morphology of the current collectors after lithium plating in Example 1 and Comparative Example 1 are as follows: Figure 1 - (c) and (d) It can be clearly seen that the current collector based on DNA composite material coating in the embodiments of the present invention can deposit a dense and uniform lithium coating on the surface, which is beneficial to suppress dendrite growth, reduce side reactions and stabilize the electrode structure; while the lithium coating deposited on the surface of a single untreated copper foil in the comparative example has lower uniformity, and porosity and obvious discontinuity are observed, and the electrical performance is more likely to degrade.

[0054] Combined with the application performance test of the current collector: Figure 2 The results of the cyclic coulombic efficiency test of the current collectors assembled into half-cells in Example 1 and Comparative Example 1 show that the uncoated copper foil half-cell in the Comparative Example showed a significant decrease in coulombic efficiency after 80 cycles, while the half-cell based on the DNA composite material-coated current collector in the Example still maintained good cell stability and coulombic efficiency after 150 cycles.

[0055] Figure 3 , 4 The cycle specific capacity test results are shown for the full cells assembled with current collectors in Example 1 and Comparative Example 1, respectively. It can be seen that the specific capacity decay of the two cells is not much different during the 5, 30 and 50 cycles. However, as the reaction continues, the specific capacity decay of the full cell with the uncoated single copper foil gradually increases, while the full cell with the current collector based on DNA composite material coating provided by the present invention still has a high specific capacity retention rate. Corresponding to the current collector performance test results, it is confirmed that it can give higher battery stability.

[0056] Comparative Example 2, using potato DNA, showed increased degradation during extraction, resulting in numerous fragmented segments and an inability to form a continuous coating layer. This led to uneven lithium-ion flux, with localized high current densities easily inducing dendrite formation. Comparative Example 3, using spinach DNA extracted via traditional methods, had a high proportion of chloroplast DNA and contained hydrophobic chlorophyll residues, increasing the contact angle to over 45°, reducing electrolyte wettability, and decreasing effective lithium deposition sites. Comparative Example 4, using commercially available salmon DNA, contained a high proportion of hydrophobic bases, exhibiting poor compatibility with polar electrolytes, decreased elastic modulus, and insufficient mechanical strength, resulting in poor suppression of lithium deposition volume expansion. Comparative Example 5, lacking refrigeration and a slow dissolution step, failed to protect the long-chain structure of the DNA-containing complex, leading to voids in the coating layer and poor results. Comparative Example 6, without the use of MEL to form the coating layer, increased the surface contact angle to 28°, causing delayed electrolyte wetting, exacerbated interfacial side reactions, and worsened results. Comparative Example 7, using other enzymes for extraction, also showed overall poor results.

[0057] In summary, this invention optimizes and improves the DNA extraction process, enabling the extracted DNA complex to largely maintain the DNA-polysaccharide complex structure. Combined with MEL to form a three-dimensional network structure for coating the copper foil surface, this enhances its mechanical strength, strengthens the inhibition of lithium deposition expansion, homogenizes lithium ion flow, eliminates the tip effect, and improves interfacial performance. Furthermore, it allows for the deposition of a dense and uniform lithium plating layer on the surface, which helps suppress dendrite growth, reduce side reactions, stabilize the electrode structure, and improve electrochemical stability, reducing degradation. This invention solves the problems existing in copper substrates in the prior art, comprehensively improving the application performance of copper current collectors.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a current collector based on DNA composite material coating, characterized in that, Includes the following steps: (1) Cut the okra and remove the seeds, then add it to water and place it at 0-10℃ for 24-36 h. Then add the enzyme hydrolysate to react and separate the solid and liquid to obtain the extract. The enzymatic hydrolysate includes β-glucanase and alginate lyase; (2) Add ethanol solution to the extract to precipitate and separate the DNA-containing complex. Mix the DNA-containing complex and melamine in a solvent to obtain a mixed solution. (3) The mixed solution is applied to the surface of the copper current collector, and after standing, it is dried to form a coating layer, thus obtaining the current collector based on the DNA composite material coating.

2. The method for preparing a current collector based on DNA composite material coating as described in claim 1, characterized in that, In step (1), the volume ratio of okra to water is 1:(1.5-2.5). And / or, in step (1), the volume ratio of water to enzymatic hydrolysate is 1:(1.2-1.6).

3. The method for preparing a current collector based on DNA composite material coating as described in claim 2, characterized in that, In the enzymatic hydrolysate of step (1), the mass-volume content of β-glucanase is 1.5-2.5%, and the mass-volume content of alginate lyase is 0.2-0.8%.

4. The method for preparing a current collector based on DNA composite material coating as described in claim 3, characterized in that, In step (1), the reaction time for adding the enzymatic hydrolysate is 8-12 min.

5. The method for preparing a current collector based on DNA composite material coating as described in claim 1, characterized in that, In step (2), the volume ratio of the extract to the ethanol solution is 1:(1-2). And / or, in step (2), the precipitation time is 4-6 min.

6. The method for preparing a current collector based on DNA composite material coating as described in claim 1, characterized in that, In step (2), after obtaining the DNA-containing complex, it is dried at room temperature for 20-30 h.

7. The method for preparing a current collector based on DNA composite material coating as described in claim 1, characterized in that, In step (2), the mass ratio of the DNA-containing complex to melamine is (1-2):1; And / or, in the mixed solution of step (2), the total mass-volume concentration of the DNA-containing complex and melamine is 3-5 mg / ml.

8. The method for preparing a current collector based on DNA composite material coating as described in claim 1, characterized in that, In step (2), the solvent is Tris buffer, the pH of which is 8.3-8.7 and the concentration is 20-35 mmol / L.

9. A current collector based on DNA composite material coating prepared by the method for preparing a current collector based on DNA composite material coating as described in any one of claims 1-8.

10. The application of the DNA composite material-coated current collector as described in claim 9 in electrochemical energy storage devices.

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