A binder based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterials, a preparation method thereof and an electrode
By preparing a binder based on cross-linked polyvinylidene fluoride-coated mesoporous carbon nanomaterials, the problem of poor bonding strength of traditional binders was solved, achieving high mechanical strength, flexibility and good conductivity of lithium-ion batteries, and improving the cycle stability of the electrodes.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-08
- Publication Date
- 2026-03-27
Smart Images
Figure CN116987465B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of lithium ion batteries, in particular to the technical field of lithium ion battery binders, and more particularly to a binder based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial and a preparation method thereof, and further to an electrode using the binder based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial. BACKGROUND
[0002] Lithium ion batteries are widely used as the main power source for mobile phones, tablet computers, notebook computers and other portable electronic products due to their relatively high energy density and relatively long cycle life, and are gradually expanding to be used as the power source for hybrid electric vehicles, electric vehicles and electric non-motor vehicles. A lithium ion battery is mainly composed of a positive electrode, a negative electrode, a separator and an electrolyte. When the battery is connected through an external circuit, due to the difference in lithium chemical potential of the positive and negative electrodes, a chemical reaction occurs on the electrodes, accompanied by a transfer process of lithium ions inside the battery, and electrons pass through the external circuit to form an electric current.
[0003] A lithium ion battery is composed of five parts: a battery shell, a positive electrode sheet, a separator, a negative electrode sheet and an electrolyte. Traditional binders are generally high molecular materials, and their main function is to uniformly and stably bond active materials, conductive additives and current collectors, avoid powder falling, peeling and falling off of the electrode sheet, form good electronic contact to ensure effective electronic circuit, and reduce the impedance of the battery. In addition, the binder can inhibit and buffer the huge volume expansion of the silicon negative electrode during repeated charge and discharge, prevent the electrode sheet from being damaged due to the large stress received during the battery cycle, and slow down the capacity decay of the battery. Traditional binders such as PVDF are bonded to the current collector through hydrogen bonds, van der Waals forces and the like, and have the problems of poor bonding strength, easy falling off of the active material, etc., resulting in poor cycle stability of the battery. SUMMARY
[0004] Therefore, the present application provides a binder based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial and a preparation method thereof, and further provides an electrode using the binder based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial to solve the problems of poor bonding strength and easy falling off of the active material of the existing binder.
[0005] In a first aspect, the present application provides a preparation method of a binder based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial, comprising the following steps:
[0006] Preparation of oxidized mesoporous carbon nanomaterial: provide a strong oxidizing solution, mesoporous carbon nanomaterial and washing liquid, the mass volume ratio of the mesoporous carbon nanomaterial to the strong oxidizing solution is 1:2-10 g / ml, the mesoporous carbon nanomaterial is added to the strong oxidizing solution, ultrasonic dispersion is carried out for 5-20 min, then it is transferred to 70-100℃ for stirring and reflux reaction for 5-60 min, after the reaction is completed, the strong oxidizing solution is centrifuged to collect the precipitate, the precipitate is washed by the washing liquid, then the centrifugation and washing steps are repeated for 1-5 times, after centrifugation and drying, the oxidized mesoporous carbon nanomaterial is prepared;
[0007] Preparation of amino acid modified PVDF: provide PVDF, alkaline dispersion system and alkaline amino acid solution, add the PVDF to the alkaline dispersion system and stir in a 60-100℃ water bath for 60-300 s, then filter the PVDF, add the PVDF to the alkaline amino acid solution, stir the alkaline amino acid solution at 55-75℃ for 0.5-5 h, while adding persulfate to the alkaline amino acid solution, after the stirring is completed, filter the PVDF to obtain the amino acid modified PVDF;
[0008] Preparation of adhesive based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial: add the amino acid modified PVDF and the oxidized mesoporous carbon nanomaterial to the first dispersion liquid and stir to mix, the mass ratio of the amino acid modified PVDF to the oxidized mesoporous carbon nanomaterial is 20-100:100, stir and reflux at 70-100℃ for 0.1-2 h, after the reaction is completed, add the acid solution containing EDC and NHS to the first dispersion liquid, transfer to 0-10℃ for continuous stirring and reflux for 10-30 min, after filtration and washing, reduce pressure distillation to prepare the adhesive based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial;
[0009] The molecular weight of the PVDF is 10-60 kD.
[0010] The application is based on a preparation method of a binder coated with cross-linked polyvinylidene fluoride and mesoporous carbon nanomaterials, which comprises a step of preparing oxidized mesoporous carbon nanomaterials, a step of preparing amino acid modified PVDF, and a step of preparing a binder coated with cross-linked polyvinylidene fluoride and mesoporous carbon nanomaterials. In the step of preparing oxidized mesoporous carbon nanomaterials, a strong oxidizing solution is used to form a large number of oxygen-containing functional groups, such as hydroxyl, carboxyl and carbonyl, on the surface of the mesoporous carbon nanomaterials through liquid-phase oxidation, and then the oxidized mesoporous carbon nanomaterials are collected through subsequent centrifugation and washing steps. In the step of preparing amino acid modified PVDF, the PVDF is fully reacted with an alkaline dispersion system to generate PVDF containing unsaturated double bonds, and a short reaction time can control the speed of dehydrohalogenation and prevent the generation of other by-products. The generated PVDF containing unsaturated double bonds is further cross-linked and grafted with alkaline amino acids, specifically, the addition reaction of the amino group in the alkaline amino acid with the unsaturated double bond generates amino acid modified PVDF. In the step of preparing a binder coated with cross-linked polyvinylidene fluoride and mesoporous carbon nanomaterials, the amino acid modified PVDF and the oxidized mesoporous carbon nanomaterials are reacted through stirring reflux, and the amino acid modified PVDF reacts with the hydroxyl, carboxyl and carbonyl on the surface of the oxidized mesoporous carbon nanomaterials through the amino group, so as to realize the coating of the amino acid modified PVDF on the mesoporous carbon nanomaterials. Finally, an acidic solution containing EDC (1- (3-dimethylaminopropyl) -3-ethyl carbodiimide hydrochloride) and NHS (N-hydroxysuccinimide) is added to the reaction system, and under acidic conditions, EDC and NHS further activate the carboxyl group in the amino acid modified PVDF, so as to realize the esterification reaction between the carboxyl group and the unreacted amino group and promote the cross-linking of PVDF. Low temperature conditions can control the intensity of the reaction and prevent the local over-cross-linking of PVDF from affecting the uniform distribution of the cross-linking reaction and the flexibility of the material itself. The binder coated with cross-linked polyvinylidene fluoride and mesoporous carbon nanomaterials has the following advantages compared with ordinary PVDF binder: (1) Compared with unmodified PVDF, the cross-linked polyvinylidene fluoride binder is cross-linked inside, so that the binder has stronger mechanical strength and toughness, can buffer the stress generated by the volume change of the active material during the charging and discharging cycle of the battery, enhances the overall strength of the electrode, and prevents the electrode from breaking or the active material from falling off. (2) The binder coated with cross-linked polyvinylidene fluoride and mesoporous carbon nanomaterials is assembled into a whole structure similar to "urchin shape", and the "urchin shape" center is a mesoporous carbon sphere. Due to its porous structure, the mesoporous carbon nanomaterial has a certain flexibility, which can buffer the internal stress caused by the volume expansion during the charging and discharging process of the lithium ion battery, and also helps the transmission of lithium ions. The "urchin shape" outside is a thorn-like amino acid modified PVDF chain, which adheres to the surrounding active material and conductive agent through the amino acid modified PVDF chain, so that it is firmly surrounded in the electrode micro-unit with the mesoporous carbon nanosphere as the center.Further, the amino acid modified PVDF chains are cross-linked with each other through a cross-linking reaction, and multiple electrode micro-units are connected through the cross-linking reaction to realize the mechanical strength and anti-falling function of the overall electrode. (3) Compared with unmodified PVDF, the binder based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterials contains a large number of carboxyl groups, amino groups and mesoporous carbon nanomaterials. The amino groups can form stable chemical bonds with copper ions, aluminum ions and the like on the surface of the current collector foil. The carboxyl and amino groups can also form strong interaction bonds such as hydrogen bonds with other components such as conductive agents, thereby enhancing the adhesion of the binder to the current collector and preventing active material cracking, peeling and the like. (4) The modified cross-linked polyvinylidene fluoride binder greatly improves the affinity of the binder to lithium ions due to the presence of carboxyl and amino functional groups and the conductive effect of the central mesoporous carbon nanospheres, facilitating lithium ion transport and improving the conductivity of the binder.
[0011] Preferably, in the step of preparing the oxidized mesoporous carbon nanomaterial, the strong oxidizing solution is at least one of nitric acid solution, hydrogen peroxide solution, potassium permanganate solution and perchloric acid solution, and the concentration of the strong oxidizing solvent is 0.1-10 mol / L. Nitric acid solution, hydrogen peroxide solution, potassium permanganate solution and perchloric acid solution all have strong oxidizing properties and can efficiently oxidize the mesoporous carbon nanomaterial to form a large number of oxygen-containing functional groups on the surface thereof.
[0012] Preferably, in the step of preparing the oxidized mesoporous carbon nanomaterial, the washing liquid is any one of water, ethanol and n-hexane; the centrifugal speed is 5000-10000 r / min, and the centrifugal time is 10-30 min. Washing can ensure that the strong oxidizing agent is not brought into the subsequent preparation steps. Generally, after washing for 2 times, the pH value of the supernatant reaches 5-7, at which time the precipitate can be transferred to the subsequent preparation steps.
[0013] Preferably, in the step of preparing the amino acid modified PVDF, the mass ratio of the PVDF, the basic amino acid and the persulfate is 100:10-30:0.1-1. The PVDF is first dehydrogenated to form PVDF containing unsaturated double bonds, and then the unsaturated double bonds react with the basic amino acid to form the amino acid modified PVDF. By controlling the mass ratio of the PVDF, the basic amino acid and the persulfate, the reactions before and after can be coordinated to effectively promote the formation of the amino acid modified PVDF.
[0014] Preferably, in the step of preparing the amino acid modified PVDF, the solute of the alkaline dispersion system is NaOH or KOH, the concentration of the solute is 0.1-2 mol / L, and the solvent of the alkaline dispersion system is at least one of water, ethanol, DMF and sodium carboxymethyl cellulose. PVDF is dissolved in the alkaline dispersion system with a suitable concentration, and PVDF is dehydrohalogenated under stirring to generate PVDF containing unsaturated double bonds. Too low concentration of the alkaline dispersion system is not conducive to the reaction, and too high concentration will lead to the generation of other by-products.
[0015] Preferably, in the step of preparing the amino acid modified PVDF, the solute of the alkaline amino acid solution is at least one of lysine, arginine and histidine, and the mass fraction of the solute in the alkaline amino acid solution is 5%-30%; the solvent of the alkaline amino acid solution is at least one of water, ethanol and polyethylene glycol.
[0016] The persulfate is any one of ammonium persulfate, sodium persulfate and potassium persulfate. The alkaline amino acid generally contains multiple amino groups, and PVDF can be grafted with the alkaline amino acid to introduce part of the amino groups at one time. The presence of multiple amino groups is conducive to the subsequent crosslinking reaction and can enhance the bonding performance of the adhesive. The amino acid is grafted onto the PVDF chain through the catalysis of the persulfate.
[0017] Preferably, in the step of preparing the amino acid modified PVDF, the mass-volume ratio of PVDF to the alkaline dispersion system is 10:10-100. By controlling the amount of PVDF and the alkaline dispersion system, the rapid generation of unsaturated double bonds is ensured.
[0018] Preferably, in the step of preparing the adhesive based on the crosslinked polyvinylidene fluoride coated mesoporous carbon nanomaterial, the first dispersion liquid is water or ethanol, the acidic solution containing EDC and NHS is that EDC and NHS are co-dissolved in one of HCl solution, H2SO4 solution and H3PO4 solution, and the pH of the acidic solution containing EDC and NHS is 0.1-1. The amino acid modified PVDF and the oxidized mesoporous carbon nanomaterial are stirred in the first dispersion liquid to graft the PVDF chain onto the surface of the mesoporous carbon nanospheres in a “urchin shape”. The surface modification of the PVDF chain can eliminate the surface charge effect of the mesoporous carbon nanospheres and prevent the agglomeration of the mesoporous carbon nanospheres. The carboxyl group on the amino acid modified PVDF is activated under the subsequent acidic condition, and the crosslinking reaction between the amino acid modified PVDF and other amino acid modified PVDF is promoted under the catalysis of EDC and NHS to generate the adhesive based on the crosslinked polyvinylidene fluoride coated mesoporous carbon nanomaterial.
[0019] Preferably, in the step of preparing the adhesive based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial, the mass ratio of the oxidized mesoporous carbon nanomaterial, EDC and NHS is 100:0.1-1:0.1-1. Reasonable preparation of the amount of oxidized mesoporous carbon nanomaterial, EDC and NHS can promote the condensation reaction of amino acids on different PVDF chains to generate amide bonds, while also avoiding the influence of excessive cross-linking of polyvinylidene fluoride adhesive on its solubility and mechanical properties.
[0020] In a second aspect, the present application also provides an adhesive based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial, which is prepared by the method of preparing the adhesive based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial of the first aspect.
[0021] The adhesive based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial of the second aspect of the present application is assembled into a "urchin-like" core-shell structure, with a mesoporous carbon nanosphere as the central core, and a chain-like PVDF grafted and grown outside the mesoporous carbon nanosphere. Each core-shell structure is cross-linked together with other core-shell structures through PVDF, to assemble the adhesive based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial of the present application. Compared with ordinary adhesives, the adhesive based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial of the present application has the advantages of high mechanical strength, strong flexibility, good electrical conductivity, excellent adhesion performance, etc.
[0022] In a third aspect, the present application also provides an electrode comprising the adhesive based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial of the second aspect of the present application.
[0023] The electrode of the present application has high anti-peeling performance, which can prevent the electrode from generating active material fracture, peeling, etc., and the assembled battery has better cycle stability and rate performance.
[0024] The advantages of the present application will be partially explained in the following description, some of which are obvious according to the description, or can be known by the implementation of the embodiments of the present application. BRIEF DESCRIPTION OF DRAWINGS
[0025] In order to more clearly explain the content of the present application, the following will be combined with the specific embodiments to explain it in detail.
[0026] Figure 1 The infrared characterization spectrum of the amino acid modified PVDF before and after the present application;
[0027] Figure 2 The simulation diagram for the adhesive performance test;
[0028] Figure 3 The result diagram for the adhesive performance test;
[0029] Figure 4 Figure 4 is a graph of the rate capability test results. DETAILED DESCRIPTION
[0030] The following describes the preferred embodiments of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, can also make several improvements and refinements, these improvements and refinements are also considered to be within the scope of the present application.
[0031] In a specific embodiment, the mesoporous carbon nanomaterial can be purchased on the market or prepared in the laboratory, and the preparation method is as follows: 1000 ml of 5% ammonia solution, 24 g of tetraethyl orthosilicate, 40 g of phenol, 25 g of acetaldehyde and 1 g of ethylenediamine are provided. First, add tetraethyl orthosilicate to the ammonia solution and ultrasonic for 15 s, thereby generating a small amount of silica nanoparticle template. Then, phenol, acetaldehyde and ethylenediamine are added dropwise to the ammonia solution and ultrasonic for 5 min, and during the continuous ultrasonic process, the phenolic resin precursor is polymerized to generate phenolic resin and is combined with the template. New silica nanoparticles and phenolic resin are continuously generated and competitively combined with the silica template, and the silica nanoparticles are embedded in the phenolic resin nanoparticles as a pore-forming agent to form a coupled structure of phenolic resin and silica doped with each other. After ultrasonic, the reaction system is centrifuged at 5000 r / min for 30 min to collect the silica nanoparticle precipitate, and the collected precipitate is transferred to 100 mL of 5 mol / L sodium hydroxide solution, stirred at 100 r / min for 5 min to remove the silica, and then the reaction system is centrifuged at 5000 r / min for 30 min to collect the precipitate, which is dried to obtain a phenolic resin nanoporous material. The phenolic resin nanoporous material is transferred to a high-temperature carbonization furnace for high-temperature carbonization for 20 min, the high-temperature carbonization furnace is filled with nitrogen, and the temperature of the high-temperature carbonization furnace is 1000°C. The precipitate after high-temperature carbonization is the mesoporous carbon nanomaterial, which is used for subsequent preparation of the binder based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial. Example 1
[0032] The binder based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial and the preparation method thereof, as well as the preparation method of the electrode comprising the binder based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial, comprise the following steps.
[0033] The step of preparing the oxidized mesoporous carbon nanomaterial is as follows: 100 g of the mesoporous carbon nanomaterial prepared in the foregoing is provided and 200 ml of a hydrogen peroxide solution with a concentration of 10 mol / L is provided, the mesoporous carbon nanomaterial is added to the hydrogen peroxide solution, ultrasonic dispersion is performed for 5 min, and then the mixture is transferred to a 100℃ stirring reflux reactor for 6 h. After the reaction is completed, the hydrogen peroxide solution is centrifuged at 10,000 r / min for 10 min to collect the precipitate, the precipitate is washed with water, and then the washing liquid is centrifuged at 10,000 r / min for 10 min to collect the precipitate, the washing and centrifuging steps are repeated 1-5 times until the pH value of the supernatant reaches 5-7. The collected precipitate is then transferred to an 80℃ oven and left to stand for 100 min, thereby obtaining the oxidized mesoporous carbon nanomaterial.
[0034] The step of preparing the amino acid modified PVDF is as follows: 1000 ml of a KOH aqueous solution with a concentration of 0.1 mol / L, 100 g of PVDF with a molecular weight of 10 kD, 200 ml of a lysine aqueous solution with a mass fraction of 10%, and 0.5 g of ammonium persulfate are provided, the PVDF is added to the KOH solution, the KOH solution is placed in a 100℃ water bath and stirred for 100 s, and after the reaction is completed, the reaction system is suction filtered to obtain the PVDF containing unsaturated double bonds. The PVDF containing unsaturated double bonds is added to the lysine solution, the lysine solution is stirred at 60℃ for 2.5 h, the ammonium persulfate is added dropwise to the lysine solution during stirring, and after the stirring is completed, suction filtration is performed to obtain the amino acid modified PVDF.
[0035] The step of preparing the binder based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial is as follows: 20 g of the amino acid modified PVDF and 100 g of the oxidized mesoporous carbon nanomaterial are added to 1000 ml of deionized water and stirred and mixed, and then the mixed system is transferred to an 80℃ stirring reflux reactor and stirred at a rotation speed of 150 r / min for 1 h. 5 ml of a hydrochloric acid solution containing EDC and NHS is provided, the concentrations of EDC and NHS are both 0.02 g / ml, and after the reaction is completed, the hydrochloric acid solution containing EDC and NHS is added to the deionized water, the mixture is transferred to a 10℃ stirring reflux reactor and stirred at a rotation speed of 150 r / min for 10 min, suction filtration and washing are performed, and then the mixture is distilled under reduced pressure at 40℃, thereby obtaining the binder based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial.
[0036] Preparation of the electrode: the binder based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial, the active material silicon monoxide (SiO x) and conductive agent carbon black were added into the aqueous ethanol solution and stirred at 300 r / min for 100 min. The mass ratio of the silicon monoxide, the binder based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial, and the conductive agent was 9:0.8:0.2. The mixed system was stirred at 50°C until the solid content was 50%, and then the mixed system was coated on the current collector copper foil. The electrode was obtained by vacuum drying at 80°C for 12 h. Example 2
[0037] The binder based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial and the preparation method thereof and the preparation method of the electrode comprising the binder based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial comprise the following steps.
[0038] The oxidized mesoporous carbon nanomaterial was prepared by providing 100 g of the aforementioned prepared mesoporous carbon nanomaterial and 400 ml of a potassium permanganate solution with a concentration of 8 mol / L. The mesoporous carbon nanomaterial was added to the potassium permanganate solution, ultrasonically dispersed for 5 min, and then transferred to a stirring reflux reactor at 100°C for 1 h. After the reaction was completed, the hydrogen peroxide solution was centrifuged at 5000 r / min for 30 min to collect the precipitate. The precipitate was washed with an aqueous ethanol solution (volume ratio of 50:50), and then centrifuged at 5000 r / min for 30 min to collect the precipitate. The washing and centrifuging steps were repeated 1-5 times until the pH value of the supernatant reached 5-7. The collected precipitate was then transferred to a 90°C oven and left to stand for 20 min to obtain the oxidized mesoporous carbon nanomaterial.
[0039] The amino acid modified PVDF was prepared by providing 1000 ml of an ethanol solution of NaOH with a concentration of 1 mol / L, 200 g of PVDF with a molecular weight of 45 kD, 200 ml of an ethanol solution of arginine with a mass fraction of 30%, and 0.1 g of sodium persulfate. The PVDF was added to the NaOH solution, and the NaOH solution was stirred in a water bath at 80°C for 240 s. After the reaction was completed, the reaction system was suction filtered to obtain the PVDF containing unsaturated double bonds. The PVDF containing unsaturated double bonds was added to the arginine solution, and the arginine solution was stirred at 75°C for 5 h. The sodium persulfate was added dropwise to the arginine solution while stirring. After the stirring was completed, the suction filtration was performed to obtain the amino acid modified PVDF.
[0040] Preparation of the adhesive based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial: 50 g of the amino acid modified PVDF and 100 g of the oxidized mesoporous carbon nanomaterial were added to 1000 ml of ethanol and stirred to mix, and then the mixed system was transferred to 85℃, stirred at a speed of 150 r / min for reflux reaction for 0.8 h. A 5 ml sulfuric acid solution containing EDC and NHS was provided, in which the concentration of EDC was 0.02 g / ml, and the concentration of NHS was 0.1 g / ml. After the reaction was completed, the sulfuric acid solution containing EDC and NHS was added to the ethanol, and was transferred to 8℃, and was continuously stirred at a speed of 150 r / min for reflux for 15 min. After filtration, washing, and distillation under reduced pressure at 50℃, the adhesive based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial was prepared.
[0041] Preparation of the electrode: the adhesive based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial and the active material silicon monoxide (SiO x ) in the present embodiment were added to an aqueous ethanol solution, and were stirred at a speed of 300 r / min for 100 min. The mass ratio of the silicon monoxide and the adhesive based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial was 9:1. The mixed system was stirred at 50℃ until the solid content was 50%, and then the mixed system was coated on a current collector copper foil, and was vacuum dried at 80℃ for 12 h to obtain the electrode. Example 3
[0042] The adhesive based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial, the preparation method thereof, and the preparation method of the electrode comprising the adhesive based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial comprise the following steps.
[0043] Preparation of the oxidized mesoporous carbon nanomaterial: 100 g of the mesoporous carbon nanomaterial prepared in the foregoing was added to 500 ml of a nitric acid solution with a concentration of 5 mol / L, and was ultrasonically dispersed for 10 min, and then was transferred to 90℃, and was stirred for reflux reaction for 2 h. After the reaction was completed, the hydrogen peroxide solution was centrifuged at a speed of 8000 r / min for 15 min to collect the precipitate. The precipitate was washed with an aqueous ethanol solution (volume ratio of 50:50), and then was centrifuged at a speed of 8000 r / min for 15 min to collect the precipitate. The washing and centrifuging steps were repeated 1-5 times until the pH value of the supernatant reached 5-7. The collected precipitate was transferred to an oven at 80℃, and was left to stand for 100 min to obtain the oxidized mesoporous carbon nanomaterial.
[0044] Preparation of amino acid modified PVDF: 1000 ml of 0.5 mol / L KOH aqueous solution, 100 g of PVDF with a molecular weight of 60 kD, 200 ml of 5% histidine ethanol solution and 0.5 g of potassium persulfate were provided, the PVDF was added to the KOH solution, the KOH solution was stirred in a 60℃ water bath for 300 s, and the reaction system was filtered to obtain PVDF containing unsaturated double bonds. The PVDF containing unsaturated double bonds was added to the histidine solution, and the lysine solution was stirred at 65℃ for 0.5 h, while the potassium persulfate was added dropwise to the histidine solution, and the amino acid modified PVDF was obtained after filtration.
[0045] Preparation of cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial based binder: 80 g of amino acid modified PVDF and 100 g of oxidized mesoporous carbon nanomaterial were added to 1000 ml of ethanol water (the mass ratio of ethanol to water was 1:1) and stirred to mix, and then the mixed system was transferred to a 90℃ water bath and stirred at a speed of 150 r / min for 0.5 h. A 5 ml phosphoric acid solution containing EDC and NHS was provided, the concentration of EDC was 0.1 g / ml, and the concentration of NHS was 0.02 g / ml. After the reaction was completed, the phosphoric acid solution containing EDC and NHS was added to the ethanol, and the mixture was transferred to a 5℃ water bath and stirred at a speed of 150 r / min for 25 min. After filtration and washing, the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial based binder was prepared by distillation under reduced pressure at 60℃.
[0046] Preparation of electrode: the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial based binder, active material silicon monoxide (SiO x ) and conductive agent carbon black in this embodiment were added to an ethanol water solution and stirred at a speed of 300 r / min for 100 min. The mass ratio of silicon monoxide, cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial based binder and conductive agent was 9:0.8:0.2. The mixed system was stirred at 50℃ until the solid content reached 50%, and then the mixed system was coated on a copper foil current collector and vacuum dried at 80℃ for 12 h to obtain an electrode. Example 4
[0047] The cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial based binder, the preparation method thereof and the preparation method of the electrode comprising the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial based binder comprise the following steps.
[0048] Preparation of oxidized mesoporous carbon nanomaterial: 100 g of the mesoporous carbon nanomaterial prepared above and 500 ml of hydrogen peroxide solution with a concentration of 2 mol / L were provided, the mesoporous carbon nanomaterial was added to the hydrogen peroxide solution, and ultrasonic dispersion was performed for 20 min, and then the mixture was transferred to a 70℃ water bath for stirring and reflux reaction for 2 h. After the reaction was completed, the hydrogen peroxide solution was centrifuged at 10,000 r / min for 10 min to collect the precipitate, and the precipitate was washed with water, and then centrifuged at 10,000 r / min for 10 min to collect the precipitate. The washing and centrifugation steps were repeated 1-5 times until the pH value of the supernatant reached 5-7. Then the collected precipitate was transferred to a 70℃ oven and left to stand for 100 min to obtain the oxidized mesoporous carbon nanomaterial.
[0049] Preparation of amino acid modified PVDF: 1000 ml of NaOH aqueous ethanol solution (ethanol and water in a mass ratio of 1:1) with a concentration of 1.5 mol / L, 200 g of PVDF with a molecular weight of 10 kD, 200 ml of lysine aqueous ethanol solution (ethanol and water in a mass ratio of 1:1) with a mass fraction of 20%, and 0.5 g of ammonium persulfate were provided. The PVDF was added to the NaOH solution, and the NaOH solution was stirred in a 70℃ water bath for 180 s. After the reaction was completed, the reaction system was suction filtered to obtain the PVDF containing unsaturated double bonds. The PVDF containing unsaturated double bonds was added to the lysine solution, and the lysine solution was stirred at 70℃ for 2 h. At the same time, the ammonium persulfate was added dropwise to the lysine solution, and after the stirring was completed, the amino acid modified PVDF was suction filtered.
[0050] Preparation of the binder based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial: 100 g of the amino acid modified PVDF and 100 g of the oxidized mesoporous carbon nanomaterial were added to 1000 ml of deionized water and stirred to mix, and then the mixture was transferred to a 70℃ water bath and stirred at a rotation speed of 150 r / min for reflux reaction for 2 h. 5 ml of hydrochloric acid solution containing EDC and NHS was provided, and the concentrations of EDC and NHS were both 0.05 g / ml. After the reaction was completed, the hydrochloric acid solution containing EDC and NHS was added to the deionized water, and the mixture was transferred to a 5℃ water bath and continued to be stirred at a rotation speed of 150 r / min for 15 min. After suction filtration and washing, the mixture was distilled under reduced pressure at 40℃ to obtain the binder based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial.
[0051] Preparation of the electrode: the binder based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial, the active material silicon monoxide (SiO x) and conductive agent carbon black were added into the aqueous ethanol solution and stirred at 300 r / min for 100 min. The mass ratio of the silicon monoxide, the binder based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial, and the conductive agent was 9:0.8:0.2. The mixed system was stirred at 50°C until the solid content was 50%, and then the mixed system was coated on the current collector copper foil. The electrode was obtained by vacuum drying at 80°C for 12 h. Example 5
[0052] The binder based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial, the preparation method thereof, and the preparation method of the electrode comprising the binder based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial comprise the following steps.
[0053] The oxidized mesoporous carbon nanomaterial was prepared by providing 100 g of the aforementioned prepared mesoporous carbon nanomaterial and 800 ml of a perchloric acid solution with a concentration of 2 mol / L. The mesoporous carbon nanomaterial was added to the perchloric acid solution, ultrasonically dispersed for 20 min, and then transferred to a stirring reflux reactor at 80°C for 1 h. After the reaction was completed, the hydrogen peroxide solution was centrifuged at 8000 r / min for 15 min to collect the precipitate. The precipitate was washed with an aqueous ethanol solution (volume ratio of 50:50), and then centrifuged at 8000 r / min for 15 min to collect the precipitate. The washing and centrifugation steps were repeated 1-5 times until the pH value of the supernatant reached 5-7. The collected precipitate was then transferred to a 100°C oven and left to stand for 30 min to obtain the oxidized mesoporous carbon nanomaterial.
[0054] The amino acid modified PVDF was prepared by providing 1000 ml of a CMC solution of KOH with a concentration of 1 mol / L, 100 g of PVDF with a molecular weight of 25 kD, 200 ml of an aqueous arginine solution with a mass fraction of 15%, and 0.8 g of sodium persulfate. The PVDF was added to the KOH solution, and the KOH solution was stirred in a water bath at 80°C for 60 s. After the reaction was completed, the reaction system was suction filtered to obtain the PVDF containing unsaturated double bonds. The PVDF containing unsaturated double bonds was added to the arginine solution, and the lysine solution was stirred at 55°C for 4 h. The sodium persulfate was added dropwise to the arginine solution while stirring, and then suction filtered to obtain the amino acid modified PVDF after the stirring was completed.
[0055] Preparation of the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial based binder: 60 g of the amino acid modified PVDF and 100 g of the oxidized mesoporous carbon nanomaterial were added to 1000 ml of ethanol and stirred to mix well, and then the mixed system was transferred to a refluxing reaction at 75℃ with stirring at a speed of 150 r / min for 1.5 h. A 5 ml sulfuric acid solution containing EDC and NHS was provided, in which the concentration of EDC was 0.2 g / ml and the concentration of NHS was 0.05 g / ml. After the reaction was completed, the sulfuric acid solution containing EDC and NHS was added to the ethanol, and then the mixed system was transferred to continue stirring at a speed of 150 r / min at 2℃ for 15 min. After filtration, washing and distillation under reduced pressure at 60℃, the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial based binder was prepared.
[0056] Preparation of the electrode: the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial based binder, active material silicon monoxide (SiO x ) and conductive agent carbon black prepared in this embodiment were added to an aqueous ethanol solution and stirred at a speed of 300 r / min for 100 min. The mass ratio of the silicon monoxide, the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial based binder and the conductive agent was 9:0.8:0.2. The mixed system was stirred at 50℃ until the solid content reached 50%, and then the mixed system was coated on a current collector copper foil and vacuum dried at 80℃ for 12 h to obtain the electrode. Example 6
[0057] The cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial based binder, the preparation method thereof and the preparation method of the electrode comprising the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial based binder comprise the following steps.
[0058] Preparation of the oxidized mesoporous carbon nanomaterial: 100 g of the mesoporous carbon nanomaterial prepared in the foregoing was added to 1000 ml of a nitric acid solution with a concentration of 1 mol / L, and then the mesoporous carbon nanomaterial was ultrasonically dispersed for 10 min and then transferred to a refluxing reaction at 100℃ with stirring. After the reaction was completed, the hydrogen peroxide solution was centrifuged at a speed of 5000 r / min for 30 min to collect the precipitate. The precipitate was washed with n-hexane, and then the washing liquid was centrifuged at a speed of 5000 r / min for 30 min to collect the precipitate. The washing and centrifuging steps were repeated 1-5 times until the pH value of the supernatant reached 5-7. The collected precipitate was transferred to a 90℃ oven and left to stand for 60 min to obtain the oxidized mesoporous carbon nanomaterial.
[0059] Preparation of amino acid modified PVDF: 1000 ml of DMF solution of NaOH with a concentration of 2 mol / L, 200 g of PVDF with a molecular weight of 40 kD, 200 ml of 10% histidine polyethylene glycol solution and 0.2 g of potassium persulfate were provided, the PVDF was added to the NaOH solution, the NaOH solution was placed in a 90°C water bath and stirred for 120 s, and after the reaction was completed, the reaction system was suction filtered to obtain PVDF containing unsaturated double bonds. The PVDF containing unsaturated double bonds was added to the histidine solution, the histidine solution was stirred at 65°C for 1 h, and the potassium persulfate was added dropwise to the histidine solution while stirring, and after the stirring was completed, the amino acid modified PVDF was suction filtered.
[0060] Preparation of cross-linked polyvinylidene fluoride-based binder coated mesoporous carbon nanomaterial: 40 g of amino acid modified PVDF and 100 g of oxidized mesoporous carbon nanomaterial were added to 1000 ml of ethanol water (with a mass ratio of ethanol to water of 1:1) and stirred to mix, and then the mixed system was transferred to 100°C, stirred at a speed of 150 r / min for 0.1 h of reflux reaction. 5 ml of sulfuric acid solution containing EDC and NHS was provided, and the concentrations of EDC and NHS were both 0.1 g / ml. After the reaction was completed, the sulfuric acid solution containing EDC and NHS was added to the ethanol water, transferred to 0°C, and continued to be stirred at a speed of 150 r / min for 30 min of reflux, and after suction filtration and washing, 50°C reduced pressure distillation was performed to prepare the cross-linked polyvinylidene fluoride-based binder coated mesoporous carbon nanomaterial.
[0061] Preparation of electrode: the cross-linked polyvinylidene fluoride-based binder coated mesoporous carbon nanomaterial, active material silicon monoxide (SiO x ) and conductive agent carbon black in this embodiment were added to an ethanol water solution and stirred at 300 r / min for 100 min. The mass ratio of silicon monoxide, cross-linked polyvinylidene fluoride-based binder coated mesoporous carbon nanomaterial and conductive agent was 9:0.8:0.2. The mixed system was stirred at 50°C until the solid content was 50%, and then the mixed system was coated on the current collector copper foil, vacuum dried at 80°C for 12 h to obtain the electrode.
[0062] Comparative Example 1
[0063] Comparative Example 1 is a common PVDF binder. Accordingly, the active material silicon monoxide, conductive agent carbon black and PVDF binder were added to an ethanol water solution and stirred at 300 r / min for 100 min. The mass ratio of silicon monoxide, PVDF binder and conductive agent was 9:0.8:0.2. The mixed system was stirred at 50°C until the solid content was 50%, and then the mixed system was coated on the current collector copper foil, vacuum dried at 80°C for 12 h to obtain the electrode.
[0064] Comparative Example 2
[0065] Comparative Example 2 differs from Example 1 only in that the final crosslinking reaction is not performed, that is, in the step of preparing the adhesive based on crosslinked polyvinylidene fluoride coated mesoporous carbon nanomaterial, 20 g of amino acid modified PVDF and 100 g of oxidized mesoporous carbon nanomaterial are added to 1000 ml of deionized water and stirred to mix, and then the mixed system is transferred to 80°C, stirred at 150 r / min for 1 h. After the reaction is completed, the reaction system is directly filtered, washed, and then distilled at 40°C under reduced pressure to prepare the adhesive based on crosslinked polyvinylidene fluoride coated mesoporous carbon nanomaterial. Then, the electrode is prepared according to the steps of preparing the electrode in Example 1.
[0066] Effect Example 1: Infrared characterization results
[0067] The unmodified PVDF in Example 1 and the amino acid modified PVDF prepared after modification are used together to prepare infrared detection samples. The infrared characterization results are shown in Figure 1 , and the main infrared spectra of the PVDF before and after modification are shown in Figure 1 . It can be seen that the infrared spectra of the PVDF before and after modification are basically the same, but at the same time, it is observed that in the infrared spectrum of the modified PVDF (upper curve), a CH2 stretching vibration absorption peak appears at 2874 cm - , and an amino group vibration absorption peak of the amino acid appears at 1580 cm - , indicating that the amino acid modified PVDF is successful.
[0068] Effect Example 2: Adhesive bonding performance test
[0069] As shown in Figure 2 , according to GB / T 2792-2014, the electrode prepared in Example 1 (modified, including the current collector copper foil and the electrode coating), the electrode prepared in Comparative Example 2 (modified, including the current collector copper foil and the electrode coating), and the electrode prepared in Comparative Example 1 (unmodified, including the current collector copper foil and the electrode coating) are bonded with the coating side to the double-sided adhesive layer, wherein the length of the coating is 200 cm and the width is 10 mm, and the other side of the double-sided adhesive layer is adhered to a rigid adherend (stainless steel plate). One clamp of the testing machine clamps the free end of the electrode and is at an angle of 180° with the stainless steel plate, and the adhesive product is pulled apart at the test rate specified in the standard. The tensile data of the two adhesives are collected by the tensile testing machine, and the results are shown in Figure 3As shown, the adhesive performance of the adhesive based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial in Example 1 is overall better than the ordinary PVDF adhesive in Comparative Example 1 and the adhesive in Comparative Example 2. At the tensile lengths of 10 cm, 20 cm, 30 cm, 40 cm and 50 cm, the corresponding adhesive strengths of the ordinary PVDF adhesive are about 0.065 N, 0.051 N, 0.045 N, 0.068 N and 0.063 N respectively, the corresponding adhesive strengths of the adhesive in Comparative Example 2 are about 0.081 N, 0.107 N, 0.116 N, 0.116 N and 0.093 N respectively, and the corresponding adhesive strengths of the modified adhesive based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial in Example 1 are about 0.106 N, 0.092 N, 0.108 N, 0.108 N and 0.114 N respectively. The results show that the adhesive based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial prepared in the present application has better adhesive performance.
[0070] Effect Example 3: Impedance test of electrode
[0071] The electrodes in Examples 1-6 and Comparative Examples 1-2 were subjected to electrochemical impedance test using an electrochemical workstation. After 20 cycles of charge and discharge, the electrodes in Examples 1-6 and Comparative Examples 1-2 were again subjected to electrochemical impedance test using an electrochemical workstation. The experimental results are shown in Table 1.
[0072] Table 1: Impedance test results of electrode
[0073] Initial electrode resistance (Ω) Electrode resistance after 20 cycles (Ω) Example 1 2.8 2.8 Example 2 3.4 3.2 Example 3 2.7 2.7 Example 4 2.6 2.6 Example 5 2.8 2.9 Example 6 2.7 2.8 Comparative Example 1 4.3 4.4 Comparative Example 2 2.7 2.8
[0074] As can be seen from the impedance test results in Table 1, in the initial resistance test and the resistance test after 20 cycles, the bulk resistance of the electrode prepared in Comparative Example 1 is obviously greater than the bulk resistance of the electrodes prepared in Examples 1-6, indicating that the adhesive prepared in Examples 1-6 has better conductive performance than the ordinary adhesive. The bulk resistance of the electrode prepared in Comparative Example 2 is roughly equivalent to the bulk resistance of the electrodes prepared in Examples 1-6.
[0075] Effect Example 4: Rate performance test
[0076] Using the electrodes in Example 1 and Comparative Example 1 and the counter electrode metal lithium sheet, and the electrolyte being 1M LiPF6 dissolved in carbonic acid diethyl ester and carbonic acid dimethyl ester (1:1), a lithium ion battery was assembled for rate performance test. The test results are shown in Table 2. Figure 4As shown, the two groups of batteries were cycled in turn at a current density of 0.2 C for 10 cycles, at a current density of 0.5 C for 10 cycles, at a current density of 1 C for 10 cycles, at a current density of 2 C for 10 cycles, at a current density of 3 C for 10 cycles, at a current density of 4 C for 10 cycles, and at a current density of 0.2 C for 10 cycles. In the first 60 cycles of the cycle test, the specific capacity of the battery corresponding to Comparative Example 1 decreased from the initial 1541 mAh.g -1 to 1326 mAh.g -1 , with a capacity retention of 86%, a large decrease; the specific capacity of the battery using the binder based on the mesoporous carbon nanomaterial coated with crosslinked polyvinylidene fluoride in Example 1 decreased from the initial 1738 mAh.g -1 to 1611 mAh.g -1 , with a capacity retention of 92.7%, and the specific capacity almost did not decay. After the test was resumed at a current density of 0.2 C, the specific capacity of the battery corresponding to Comparative Example 1 was restored to 1482 mAh.g -1 (equivalent to 96.2% of the initial specific capacity), and the specific capacity of the battery in Example 1 was restored to 1726 mAh.g -1 (99.3%). The results show that, compared with the ordinary PVDF binder, the battery using the binder based on the mesoporous carbon nanomaterial coated with crosslinked polyvinylidene fluoride has better rate performance and cycle stability.
[0077] The above-described examples only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent of the present application. It should be noted that, for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of protection of the present application. Therefore, the scope of protection of the patent of the present application should be subject to the appended claims.
Claims
1. A method for preparing a binder based on cross-linked polyvinylidene fluoride-coated mesoporous carbon nanomaterial, characterized by, The method comprises the following steps: Preparation of oxidized mesoporous carbon nanomaterial: providing a strong oxidizing solution, mesoporous carbon nanomaterial and a washing solution, the mass-volume ratio of the mesoporous carbon nanomaterial to the strong oxidizing solution is 1:2-10 g / ml, adding the mesoporous carbon nanomaterial to the strong oxidizing solution, ultrasonic dispersion for 5-20 min, then transferring to 70-100℃ for stirring and reflux reaction for 5-60 min, after the reaction, centrifuging the strong oxidizing solution to collect the precipitate, washing the precipitate with the washing solution, repeating the centrifugation and washing steps 1-5 times, and drying the precipitate after centrifugation to obtain the oxidized mesoporous carbon nanomaterial; Preparation of amino acid modified PVDF: providing PVDF, an alkaline dispersion system and an alkaline amino acid solution, adding the PVDF to the alkaline dispersion system and stirring in a 60-100℃ water bath for 60-300 s, then adding the PVDF to the alkaline amino acid solution, stirring the alkaline amino acid solution at 55-75℃ for 0.5-5 h, adding persulfate to the alkaline amino acid solution while stirring, and then filtering to obtain the amino acid modified PVDF; Preparation of a binder based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial: adding the amino acid modified PVDF and the oxidized mesoporous carbon nanomaterial to a first dispersion liquid and stirring to mix, the mass ratio of the amino acid modified PVDF to the oxidized mesoporous carbon nanomaterial is 20-100:100, stirring and reflux reaction at 70-100℃ for 0.1-2 h, after the reaction, adding an acidic solution containing EDC and NHS to the first dispersion liquid, transferring to continue stirring and reflux at 0-10℃ for 10-30 min, filtering, washing and then distilling under reduced pressure to obtain the binder based on cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial; The molecular weight of the PVDF is 10-60 kD.
2. The method for preparing a binder based on cross-linked polyvinylidene fluoride-coated mesoporous carbon nanomaterial according to claim 1, characterized in that, In the step of preparing the oxidized mesoporous carbon nanomaterial, the strong oxidizing solution is at least one of nitric acid solution, hydrogen peroxide solution, potassium permanganate solution and perchloric acid solution, and the concentration of the strong oxidizing solution is 0.1-10 mol / L.
3. The method for preparing the binder based on cross-linked polyvinylidene fluoride-coated mesoporous carbon nanomaterials as described in claim 1, characterized in that, In the step of preparing the oxidized mesoporous carbon nanomaterial, the washing solution is any one of water, ethanol and n-hexane, the centrifugation speed is 5000-10000 r / min, and the centrifugation time is 10-30 min.
4. The method for preparing a binder based on cross-linked polyvinylidene fluoride-coated mesoporous carbon nanomaterial according to claim 1, characterized by, In the step of preparing the amino acid modified PVDF, the mass ratio of the PVDF, the alkaline amino acid and the persulfate is 100:10-30:0.1-1.
5. The method for preparing the binder based on cross-linked polyvinylidene fluoride-coated mesoporous carbon nanomaterials as described in claim 1, characterized in that, In the step of preparing the amino acid modified PVDF, the solute of the alkaline dispersion system is NaOH or KOH, the concentration of the solute is 0.1-2 mol / L, and the solvent of the alkaline dispersion system is at least one of water, ethanol, DMF and sodium carboxymethyl cellulose.
6. The method for preparing the binder based on cross-linked polyvinylidene fluoride-coated mesoporous carbon nanomaterials as described in claim 1, characterized in that, In the step of preparing the amino acid modified PVDF, the solute in the basic amino acid solution is at least one of lysine, arginine and histidine, the mass fraction of the solute in the basic amino acid solution is 5% to 30%, and the solvent in the basic amino acid solution is at least one of water, ethanol and polyethylene glycol; The persulfate is any one of ammonium persulfate, sodium persulfate and potassium persulfate.
7. The method for preparing the binder based on cross-linked polyvinylidene fluoride-coated mesoporous carbon nanomaterials as described in claim 1, characterized in that, In the step of preparing the adhesive based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial, the first dispersion liquid is water or ethanol, the acidic solution containing EDC and NHS is that EDC and NHS are co-dissolved in one of HCl solution, H2SO4 solution and H3PO4 solution, and the pH of the acidic solution containing EDC and NHS is 0.1 to 1.
8. The method for preparing the binder based on cross-linked polyvinylidene fluoride-coated mesoporous carbon nanomaterials as described in claim 1, characterized in that, In the step of preparing the adhesive based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial, the mass ratio of the oxidized mesoporous carbon nanomaterial, EDC and NHS is 100:0.1 to 1:0.1 to 1.
9. An adhesive based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial prepared by the method of claim 1 to 8.
10. An electrode characterized by, The adhesive based on the cross-linked polyvinylidene fluoride coated mesoporous carbon nanomaterial of claim 9.