A current collector based on DNA composite material coating and a preparation method and application thereof

Abstract

The present application relates to a kind of based on DNA composite material coating current collector and its preparation method and application, belong to electrochemical energy storage technical field.The preparation method of current collector provided by the present application includes the following steps: (1) after cutting and removing seed of abelmoschus esculentus, it is added into water, after being placed at 0-10 ℃ for 24-36 h, enzyme solution is added to react, solid-liquid separation is obtained to extract liquor;(2) precipitate is added to extract liquor with ethanol solution, and separation is obtained to contain DNA complex, and the mixed solution is obtained by mixing DNA-containing complex and melamine in solvent;(3) the mixed solution is covered on the surface of copper current collector, after standing, dry formation coating layer, to obtain based on DNA composite material coating current collector.The current collector provided by the present application can improve the specific capacity retention rate of battery, so that battery has better stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochemical energy storage, and in particular to a current collector coated with a DNA composite material and a preparation method and application thereof. BACKGROUND

[0002] Copper has become an ideal substrate for lithium metal deposition due to its high electrical conductivity, chemical inertness and low cost. It directly affects the performance of the battery by regulating the nucleation and growth behavior of lithium. Lithium metal itself has ultra-high theoretical capacity and extremely low electrochemical potential, which can significantly improve the energy density of the full battery. Currently, the application optimization of copper current collector mainly focuses on three aspects: interface engineering optimization, which improves the interface stability and ion conduction by constructing inorganic, organic / polymer or composite artificial SEI layers, designing high-concentration and local high-concentration electrolyte and solid-state electrolyte; structure design, which reduces the local current density and provides a directional deposition channel by using 3D porous copper (such as nano-porous copper, copper nanowire array), and homogenizes lithium ion flow through surface modification methods such as lithiumophilic coating and carbon material composite; and pressure regulation to improve the interface contact, and in-situ characterization techniques such as cryo-EM and X-ray tomography to observe lithium deposition and SEI layer evolution. Many technologies have achieved the results of improving the cycle performance.

[0003] Current copper current collectors still have significant defects in application, and the core problems are concentrated in the copper substrate itself: first, the distribution of lithium ions on the surface of the uncoated copper is uneven, which easily leads to the formation of lithium dendrites, which not only affects the performance stability of the battery, but also may cause safety hazards; second, the battery assembled based on uncoated copper has poor cycle performance and low coulomb efficiency, which is difficult to meet the demand for long cycle life and high reversibility of high energy density batteries; third, the unprocessed copper surface has poor affinity with the electrolyte, which further aggravates the unevenness of lithium deposition, forming a vicious cycle of performance degradation.

[0004] Therefore, it is urgent to develop a surface coating treatment method for copper current collectors to make the surface lithium deposition uniform and avoid the formation of lithium dendrites, improve the cycle coulomb efficiency, and comprehensively improve the application performance of copper current collectors. SUMMARY

[0005] The present application aims to overcome the shortcomings of the prior art and provide a current collector coated with a DNA composite material and a preparation method and application thereof. The surface of the current collector coated with a DNA composite material provided by the present application can form a dense and uniform lithium deposition layer, further avoid the formation of lithium dendrites, and improve the stability of electrochemical energy storage devices.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0007] In a first aspect, the present application provides a preparation method of a current collector coated with a DNA composite material, comprising the following steps:

[0008] (1) After cutting off the seeds of okra and adding water, placing it at 0-10℃ for 24-36 h, adding enzyme solution for reaction, and then solid-liquid separation to obtain an extraction solution;

[0009] The enzyme solution comprises β-glucanase and alginate lyase;

[0010] (2) Adding an ethanol solution to the extraction solution for precipitation, and then separation to obtain a DNA-containing composite, and mixing the DNA-containing composite and melamine in a solvent to obtain a mixed solution;

[0011] (3) Covering the mixed solution on the surface of a copper current collector, standing and drying to form a coating layer, and then obtaining the current collector coated with the DNA composite material.

[0012] The technical scheme of the present application is to extract an extraction composite of okra DNA by using specific steps, and then combine it with melamine to coat the current collector. The extraction raw material okra used is the tender pod of Coffea gigantea, which is the edible part of okra, and is picked about 4-7 days after flowering, with a fresh green color. Compared with other plant DNA, the DNA in the mucilage of okra has high molecular weight and high polymerization degree, and can form a more dense and continuous network film after coating the current collector, effectively homogenizing the lithium ion flow and reducing the risk of lithium branches. The okra DNA forms a natural DNA-polysaccharide complex with mucilage polysaccharides (pectin, galactan, etc.), has a multi-hydroxyl structure, enhances the hydrophilicity and wettability with electrolyte, and at the same time enhances the metal chelating ability of DNA, increases the copper binding sites, and improves the interface stability.

[0013] The present application cuts the okra into small pieces and removes the okra seeds, which facilitates full extraction. First, it is placed under cold storage conditions for a certain period of time, so that the DNA in the mucilage of okra and the mucilage polysaccharides are slowly dissolved in water, protecting the integrity of the natural DNA-polysaccharide complex in okra, maintaining the long-chain DNA structure (>20 kbp) of okra, and avoiding the formation of hollow coating layer caused by mechanical rupture. Further adding β-glucanase and alginate lyase plays a role in targeted degradation of cell wall polysaccharides, selectively releasing the DNA-polysaccharide complex without damaging the phosphodiester bond or mucilage polysaccharide structure, obtaining an extraction solution containing a DNA-containing composite comprising a relatively intact DNA-polysaccharide complex, which retains a high density of polar groups (-OH / -PO4) and ensures lithium affinity.

[0014] The DNA and mucopolysaccharide complex is dehydrated and co-precipitated into a three-dimensional network by adding an ethanol solution to form flocculation, and the film flexibility is improved. On the basis of DNA-polymer complex, melamine (MEL) is further introduced: on the one hand, the triazine ring of MEL can form a hydrogen bond network with the phosphate group of DNA to improve the mechanical strength of the coating layer and inhibit lithium deposition stress cracking; on the other hand, the nitrogen-rich structure of MEL can provide negative adsorption sites to homogenize the lithium ion flow and eliminate the tip effect; and the decomposition temperature of MEL is > 300 DEG C, 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 an ion rapid channel to improve the current performance. Without MEL, problems such as delayed electrolyte infiltration, intensified interface side reaction, and decreased mechanical strength may occur.

[0015] The current collector coated by the DNA composite material provided by the application can improve the mechanical strength of the current collector, enhance the inhibition of lithium deposition expansion, homogenize the lithium ion flow, eliminate the tip effect, improve the interface performance, and can also deposit a dense and uniform lithium plating layer on the surface, which is beneficial to inhibit dendrite growth, reduce side reactions, stabilize the electrode structure, and improve the electrochemical stability performance, and reduce attenuation.

[0016] Preferably, in the step (1), the volume ratio of okra to water is 1: (1.5-2.5);

[0017] Further preferably, in the step (1), the volume ratio of okra to water is 1:2.

[0018] Preferably, in the step (1), the volume ratio of water to enzyme solution is 1: (1.2-1.6);

[0019] Further preferably, in the step (1), the volume ratio of water to enzyme solution is 1:1.4.

[0020] Preferably, in the step (1), after the okra is added with water, the treatment condition is 24 h at 4 DEG C.

[0021] Preferably, in the enzyme solution of the step (1), the mass-volume content of beta-glucanase is 1.5-2.5 %, and the mass-volume content of alginate lyase is 0.2-0.8 %;

[0022] Further preferably, in the enzyme solution of the step (1), the mass-volume content of beta-glucanase is 2 %, and the mass-volume content of alginate lyase is 0.5 %.

[0023] Further preferably, in the step (1), the reaction time of adding the enzyme solution is 8-12 min.

[0024] Preferably, in the step (2), the volume ratio of ethanol in the ethanol solution is 95%.

[0025] Preferably, in the step (2), the volume ratio of the extraction solution and the ethanol solution is 1:(1-2).

[0026] Further preferably, in the step (2), the volume ratio of the extraction solution and the ethanol solution is 1:1.5.

[0027] Preferably, in the step (2), the precipitation time is 4-6 min.

[0028] Preferably, in the step (2), after obtaining the DNA-containing complex, drying treatment is performed, and the drying is performed at room temperature for 20-30 h.

[0029] Preferably, in the step (2), the mass ratio of the DNA-containing complex and the melamine is (1-2):1.

[0030] Preferably, in the step (2), the mass ratio of the DNA-containing complex and the melamine is one of 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 or a range value of any two thereof.

[0031] Further preferably, in the step (2), the mass ratio of the DNA-containing complex and the melamine is 1:1.5. When the mass ratio of the DNA-containing complex and the MEL is 1:1.5, electrode polarization can be avoided; and the three-dimensional network has high compactness, which can reduce the exposed area of the copper foil and has better coating effect.

[0032] Preferably, in the step (2), the total mass volume concentration of the DNA-containing complex and the melamine in the mixed solution is 3-5 mg / ml.

[0033] Preferably, in the step (2), the total mass volume concentration of the DNA-containing complex and the melamine in the mixed solution is one of 3 mg / ml, 3.5 mg / ml, 4 mg / ml, 4.5 mg / ml, 5 mg / ml or a range value of any two thereof.

[0034] Preferably, in the step (2), the solvent is a Tris buffer, the pH of the Tris buffer is 8.3-8.7, and the concentration is 20-35 mmol / L.

[0035] Further preferably, in the step (2), the solvent is a Tris buffer, the pH of the Tris buffer is 8.5, and the concentration is 30 mmol / L.

[0036] Tris buffer refers to a buffer of a tris-hydroxymethyl aminomethane-hydrochloric acid buffer system.

[0037] In a second aspect, the application provides a DNA composite material coated current collector prepared by the method for preparing a DNA composite material coated current collector.

[0038] In a third aspect, the application provides application of the DNA composite material coated current collector in an electrochemical energy storage device.

[0039] Compared with the prior art, the application has the following beneficial effects:

[0040] (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 rupture;

[0041] (2) On the basis of 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 at the same time improve the interface performance, so that the dense and high-uniformity lithium deposition layer is obtained by plating lithium, which is conducive to improving the electrochemical stability;

[0042] (3) By adjusting the mass ratio of the 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 improved, and the application performance is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 Fig. 2 is a SEM image of the surface of the DNA composite material coated current collector of Example 1; Fig. 3 is a SEM image of the surface of the pure copper foil of Comparative Example 1; Fig. 4 is a SEM image of the surface of the DNA composite material coated current collector of Example 1 after plating lithium; and Fig. 5 is a SEM image of the surface of the pure copper foil of Comparative Example 1 after plating lithium.

[0044] Figure 2 Fig. 6 is a graph of the cycle coulombic efficiency test results of the current collector in Example 1 and Comparative Example 1 assembled into a half battery;

[0045] Figure 3 Fig. 7 is a graph of the cycle specific capacity test results of the current collector in Example 1 assembled into a full battery;

[0046] Figure 4 Fig. 8 is a graph of the cycle specific capacity test results of the current collector in Comparative Example 1 assembled into a full battery. DETAILED DESCRIPTION

[0047] For better illustrating the purposes, technical solutions and advantages of the present application, the present application will be further described in combination with specific examples. The test methods used in the following examples are conventional methods unless otherwise specified; the materials, reagents and the like used are reagents and materials available from commercial channels unless otherwise specified.

[0048] The enzymes used in the following examples and comparative examples are as follows:

[0049] Beta-glucanase: D888657, purchased from Shanghai Macklin Biological Reagents;

[0050] Alginase: PA93791, purchased from Guangdong Wenglong Chemical Reagents;

[0051] Pectinase: Pectinase Y-23, purchased from Shanghai Macklin Biological Reagents.

[0052] Example 1

[0053] Based on an embodiment of the present application, the preparation method of the current application is as follows:

[0054] (1) The okra (tender pod of Coffea caudata) was purchased from Jingdong e-commerce platform, washed, cut into about 3 cm*3 cm*3 cm size, and the seeds were removed. Then, the okra was placed in a bottle with 2 times the volume of deionized water, and stored at 4°C for 24 h;

[0055] Beta-glucanase and alginase were added to 1 mM EDTA phosphate buffer to prepare enzyme solution, wherein the mass volume content of beta-glucanase was 2%, and the mass volume content of alginase was 0.5%.

[0056] The enzyme solution was added to the sample solution after cold storage (the volume ratio of deionized water to enzyme solution was 1:1.4), and after standing for 10 min, the filtrate was obtained by filtering the residue to obtain the extract.

[0057] (2) The volume concentration of the ethanol solution added to the obtained extract was 95% (the volume ratio of the extract to the ethanol solution was 1:1.5), and after standing for 5 min, the upper flocculent material was picked out with a glass rod, which was a DNA-containing complex including okra DNA and mucopolysaccharide;

[0058] The DNA-containing complex was placed in a culture dish and dried in a 25 °C incubator for 24 h; melamine (MEL) powder was mixed with the dried DNA-containing complex in a mass ratio of 1.5:1 to obtain DNA@MEL, and a 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 of DNA@MEL with a mass-volume concentration of 4 mg / ml.

[0059] (3) A copper foil with a size of 10 cm*10 cm was prepared, the surface oxide layer was polished off, and then the copper foil was fully immersed in the prepared DNA@MEL mixed solution, and was allowed to stand for 20 minutes to allow the DNA-mucopolysaccharide-MEL in the mixed solution to fully coat the surface; the copper foil was taken out, the surface was gently washed with deionized water to remove the excess solution that did not react, and was dried in a 25 °C incubator to obtain the current collector coated with the DNA composite material.

[0060] Example 2

[0061] Example 2 differs from Example 1 only in that the mass ratio of MEL powder to the dried DNA-containing complex in step (2) is changed to 2:1.

[0062] Example 3

[0063] Example 3 differs from Example 1 only in that the mass ratio of MEL powder to the dried DNA-containing complex in step (2) is changed to 1:1.

[0064] Example 4

[0065] Example 4 differs from Example 1 only in that the amount of DNA@MEL added in step (2) is changed, and a mixed solution of DNA@MEL with a mass-volume concentration of 3 mg / ml is prepared.

[0066] Example 5

[0067] Example 5 differs from Example 1 only in that the amount of DNA@MEL added in step (2) is changed, and a mixed solution of DNA@MEL with a mass-volume concentration of 5 mg / ml is prepared.

[0068] Comparative Example 1

[0069] The current collector of Comparative Example 1 is the same copper foil as in step (3) of Example 1, but without coating treatment.

[0070] Comparative Example 2

[0071] The difference between Comparative Example 2 and Example 1 is only that the extraction raw material in step (1) is replaced by potato tubers purchased from Jingdong e-commerce platform, and after removing the skin, a proper amount of the potato tubers is cut and extracted to prepare the corresponding current collector.

[0072] Comparative Example 3

[0073] The difference between Comparative Example 3 and Example 1 is that the extraction raw material is replaced by spinach leaves purchased from Jingdong e-commerce platform, and after a proper amount of the spinach leaves is cut, DNA is extracted by using a traditional CTAB method, as follows:

[0074] (1) The fresh spinach leaves are cut and placed in a mortar, and a proper amount of liquid nitrogen is poured into the mortar. After the leaves are completely frozen, they are quickly ground into powder, and then mixed with a CTAB extraction buffer in a centrifuge tube. The tube is placed in a 65°C constant temperature water bath for 60 min, and the tube is inverted 1-2 times every 10-15 min during the period. The tube is placed at room temperature for 5 min. The mass-volume ratio of the spinach leaves to the CTAB buffer is controlled at about 1 g:8 mL;

[0075] (2) An equal volume of chloroform-isopentanol mixed solution is added to the centrifuge tube, and the tube is inverted 10-20 times. The tube is placed at room temperature for 10 min, and then centrifuged at 4°C and 12000 rpm for 15 min. After centrifugation, the solution is divided into three layers, and the upper aqueous phase is taken to avoid mixing with the middle and lower organic phases, and then transferred to a new centrifuge tube.

[0076] (3) An equal volume of pre-cooled isopropyl alcohol is added to the aqueous phase, and the tube is inverted 5-10 times until white flocculent precipitate appears. The tube is placed at -20°C for 2 h, and then centrifuged at 4°C and 12000 rpm for 10 min to obtain the active substance containing DNA. The active substance is washed with 70% ethanol, and then centrifuged. The washing is repeated twice, and the supernatant is removed. The active substance powder containing DNA is obtained by air-drying at room temperature.

[0077] The current collector is prepared by coating the solution prepared by referring to the matching concentration of steps (2) and (3) and MEL.

[0078] Comparative Example 4

[0079] The difference between Comparative Example 4 and Example 1 is that commercially available salmon sperm DNA is used, and the current collector is prepared by coating the solution prepared by referring to the matching concentration of steps (2) and (3) and MEL.

[0080] Comparative Example 5

[0081] The difference between Comparative Example 5 and Example 1 is only that, after water is added in step (1), the enzyme solution is directly added for reaction at room temperature to prepare the corresponding current collector.

[0082] Comparative Example 6

[0083] Comparative Example 6 differs from Example 1 only in that no MEL is added in step (2), and only the DNA-containing complex is used to prepare the mixed solution with a concentration of 4 mg / ml, to prepare the corresponding current collector.

[0084] Comparative Example 7

[0085] Comparative Example 7 differs from Example 1 only in that the β-glucanase used in step (1) is replaced by the same amount of pectinase.

[0086] Effect Example

[0087] To explore the application performance of the current collector coated with the DNA complex material provided by the application and the effectiveness of the preparation method thereof, the following tests are performed:

[0088] (I) Current collector related tests

[0089] 1. Surface contact angle of the current collector: detected by an optical contact angle measuring instrument, and the contact angle is calculated by analysis software;

[0090] 2. Elastic modulus of the current collector: according to the test method of GB / T 22315;

[0091] 3. Surface coating condition of the current collector: the surface morphology of the coating layer after coating is observed and analyzed by SEM, and whether there is a situation of copper foil exposure caused by coating layer cavities.

[0092] (II) Application performance test of the current collector

[0093] 1. Lithium plating: lithium is plated on the surface of the current collector in the examples and comparative examples, respectively, with a current density of 1 mA·cm -2 , a surface capacity of 3 mAh·cm -2 , and the surface morphology of the current collector after lithium plating is analyzed by SEM;

[0094] 2. Half-cell assembly:

[0095] Current collector: the current collector in the above examples and comparative examples is used, respectively;

[0096] Electrolyte: lithium-sulfur electrolyte;

[0097] Counter electrode: metal lithium sheet;

[0098] Separator: Celgard2325 (PP / PE / PP three layers);

[0099] Battery shell: CR2032 button cell shell;

[0100] Assembling sequence: negative electrode shell, lithium sheet, electrolyte (40 μL), separator, electrolyte (40 μL), working electrode, gasket, spring sheet, positive electrode shell.

[0101] 3. Full battery assembly:

[0102] Negative electrode: the current collector is the current collector in the above examples and comparative examples;

[0103] Positive electrode: the active material layer with a mass ratio of active material LiCoO2: conductive agent Super P: binder PVDF = 8:1:1 is coated on an aluminum foil to obtain a positive electrode;

[0104] Electrolyte: lithium hexafluorophosphate (LiPF6);

[0105] Separator: Celgard2325 (PP / PE / PP three layers);

[0106] Battery shell: CR2032 button cell shell;

[0107] 4. Cycle test conditions: the test procedure parameters are shown in Table 1.

[0108] Table 1 Cycle test procedure parameters

[0109]

[0110] The 150 cycle coulombic efficiency of the half battery prepared by using the above cycle conditions, and the specific capacity change of the full battery prepared under 5, 30, 50, 100, and 120 cycles are tested.

[0111] The above test results are shown in Table 2 and Figures 1-4 .

[0112] Table 2 Performance test results of the current collectors in the examples and comparative examples

[0113]

[0114] From the test results, it can be seen that:

[0115] Compared with the comparative examples, the surface contact angle of the current collector coated with the DNA composite material provided in the examples of the present application is smaller, and the hydrophilicity is strong, which is beneficial to electrolyte infiltration, improves the interface stability, and inhibits the side reaction; at the same time, the elastic modulus is higher, and the mechanical property is good, which is beneficial to inhibiting the volume expansion of lithium deposition. The morphology of the surface of the copper foil in Comparative Example 1 observed by scanning electron microscopy (SEM) is shown in 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 coated with the DNA composite material prepared in Example 1 observed by scanning electron microscopy (SEM) is shown in Figure 1(b), it can be seen that the current collector surface forms a relatively dense and uniform coating film, and no coating layer cavity or copper foil exposure is observed. The surface morphology of the current collector after lithium plating in Example 1 and Comparative Example 1 is shown in Figure 1 (c), (d), it can be clearly seen that the current collector coated with the DNA composite material in the embodiment of the application can deposit a dense and uniform lithium plating layer on the surface, which is conducive to inhibiting dendrite growth, reducing side reactions, and stabilizing the electrode structure; in contrast, the lithium plating layer deposited on the surface of the single untreated copper foil in the comparative example has lower uniformity, and pores and obvious discontinuity are observed, and the electrical performance is prone to degradation.

[0116] Application performance test of the current collector: Figure 2 The cycle coulombic efficiency test results of the half-battery assembled with the current collector in Example 1 and Comparative Example 1 show that the half-battery of the uncoated copper foil in the comparative example has a significant decrease in coulombic efficiency after 80 cycles, while the half-battery of the current collector coated with the DNA composite material in the embodiment still maintains good battery stability and coulombic efficiency after 150 cycles.

[0117] Figure 3 , 4 The cycle specific capacity test results of the full battery assembled with the current collector in Example 1 and Comparative Example 1 show that the specific capacity attenuation of the two is not much different during 5, 30, and 50 cycles, but as the reaction continues, the specific capacity attenuation of the full battery of the single copper foil gradually increases, while the full battery of the current collector coated with the DNA composite material provided by the application still has a high specific capacity retention rate, which corresponds to the performance test results of the current collector and confirms that it can provide higher battery stability.

[0118] In Comparative Example 2, potato DNA is extracted, which is more prone to degradation during extraction, resulting in many broken fragments and unable to form a continuous coating layer, leading to uneven lithium ion flux and local high current density easily causing dendrites. In Comparative Example 3, spinach DNA is extracted using a traditional method, and the proportion of chloroplast DNA is high, containing residual hydrophobic chlorophyll, which increases the contact angle to more than 45°, reduces the wettability of the electrolyte, and reduces the effective lithium deposition site. In Comparative Example 4, commercially available salmon sperm DNA is used, which contains a high proportion of hydrophobic bases, has poor compatibility with polar electrolyte, and has a decrease in elastic modulus and insufficient mechanical strength, which is not good for inhibiting lithium deposition volume expansion. In Comparative Example 5, no cold storage treatment is performed, and there is no slow dissolution step to protect the long-chain structure of the DNA-containing composite, resulting in a hollow coating layer and poor effect. In Comparative Example 6, MEL is not used to form a coating layer, which increases the surface contact angle to 28°, delays the electrolyte wettability, intensifies the interface side reaction, and the effect is poor. In Comparative Example 7, other enzymes are used for extraction, and the overall effect is also poor.

[0119] In summary, the present application optimizes the extraction step of the improved DNA, so that the extracted DNA complex can maintain the DNA-polysaccharide complex structure to a greater extent, and form a three-dimensional network structure with MEL to coat the surface of the copper foil, which can improve the mechanical strength, enhance the inhibition of lithium deposition expansion, and homogenize the lithium ion flow, eliminate the tip effect, while improving the interface performance, and can deposit a dense and uniform lithium plating layer on the surface, which is conducive to inhibiting dendrite growth, reducing side reactions, stabilizing the electrode structure and improving the electrochemical stability performance, reducing attenuation, solving the problems of the copper matrix in the prior art, and comprehensively improving the application performance of the copper current collector.

[0120] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A method for preparing a current collector coated with a DNA composite material, characterized by, The method comprises the following steps: (1) after cutting off the seeds of okra and adding water, placing at 0-10℃ for 24-36 h, adding enzyme solution for reaction, and separating the solid and liquid to obtain an extraction solution; The enzyme solution comprises β-glucanase and alginate lyase; (2) adding an ethanol solution to the extraction solution for precipitation, separating to obtain a DNA-containing compound, mixing the DNA-containing compound and melamine in a solvent to obtain a mixed solution; (3) covering the mixed solution on the surface of a copper current collector, standing and drying to form a coating layer, and obtaining the current collector coated with the DNA composite material.

2. The method for preparing a current collector based on DNA composite material coating as described in claim 1, characterized in that, In the step (1), the volume ratio of okra to water is 1:(1.5-2.5); And / or, in the step (1), the volume ratio of water to enzyme solution 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 enzyme solution of the 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 of claim 3, wherein the DNA composite material-coated current collector is prepared by the steps of: (a) preparing a DNA composite material solution by dissolving a DNA composite material in a solvent; (b) coating the DNA composite material solution on a current collector; and (c) drying the coated current collector. In the step (1), the reaction time for adding the enzyme solution 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 the step (2), the volume ratio of the extraction solution to the ethanol solution is 1:(1-2); And / or, in the 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 the step (2), after obtaining the DNA-containing compound, drying treatment is performed, and the drying is performed 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 the step (2), the mass ratio of the DNA-containing compound to melamine is (1-2):1; And / or, in the mixed solution of the step (2), the total mass-volume concentration of the DNA-containing compound 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 the step (2), the solvent is Tris buffer, the pH of the Tris buffer is 8.3-8.7, and the concentration is 20-35 mmol / L.

9. The current collector coated with the DNA composite material prepared by the method of any one of claims 1-8.

10. The current collector coated with the DNA composite material of claim 9, applied in an electrochemical energy storage device.

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