Benzoquinone substance coated Prussian blue composite material as well as preparation method and application thereof

Abstract

The invention discloses a benzoquinone substance coated Prussian blue composite material as well as a preparation method and application thereof. A specific benzoquinone substance with a unique molecular structure and electrochemical activity is selected, and a special functional group contained in the specific benzoquinone substance can be specifically combined with surface active sites of Prussian blue. The preparation method comprises the following steps: accurately regulating and controlling process parameters in chemical modes such as a chemical pulse deposition method and the like, so that a benzoquinone substance precursor is subjected to in-situ polymerization on the surface of Prussian blue, and uniform and thickness-controllable coating of a benzoquinone substance on the surface of a Prussian blue particle is realized; meanwhile, the structure stability of the Prussian blue is remarkably improved, the electronic conductivity is enhanced, and the ion diffusion rate is increased, so that the cycle performance, the rate capability and the energy density of the sodium-ion battery are greatly improved, and the preparation method is simple and controllable and has large-scale industrial production potential.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion battery positive electrode materials, and in particular to a benzoquinone-based substance-coated Prussian blue composite material, a preparation method thereof, and an application thereof. Background Art

[0002] Prussian blue (PB) and its analogues (PBAs), as a typical open-frame structure material, are considered to be promising cathode materials for sodium-ion batteries due to their low cost, simple synthesis, and high specific capacity. However, there are still some problems that need to be solved in the practical application of Prussian blue materials, such as: (1) Poor structural stability: During the charge and discharge process, Prussian blue materials are prone to structural collapse, resulting in capacity decay and decreased cycle performance. (2) Poor conductivity: The intrinsic conductivity of Prussian blue materials is poor, which limits the improvement of their rate performance. (3) Interfacial side reactions: There are interfacial side reactions between Prussian blue materials and electrolytes, which lead to reduced coulombic efficiency and shortened cycle life.

[0003] To address these issues, researchers have tried various modification methods, with surface coating being an effective approach. Traditional coating materials are mostly inorganic, such as carbon materials and metal oxides. While these can improve the electrochemical properties of Prussian blue to a certain extent, they still suffer from weak bonding between the coating and the substrate, as well as uneven coating. Summary of the Invention

[0004] The present invention aims to address the problems of poor structural stability, poor conductivity, and interfacial side reactions of Prussian blue. The invention provides a benzoquinone-coated Prussian blue composite material, its preparation method, and its application. The method employs a pulsed laser deposition method to achieve uniform, controllable coating of the benzoquinone on the surface of Prussian blue particles. The pulsed laser deposition method utilizes laser energy to directly deposit the benzoquinone on the surface of Prussian blue and form chemical bonds. This method can precisely control the thickness and uniformity of the coating layer, significantly improving the electrochemical performance and structural stability of the Prussian blue material. The method is suitable for large-scale production and has broad application prospects.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a composite material of Prussian blue coated with a benzoquinone substance, the method comprising:

[0007] Step 1: Preparation of a Prussian blue target: Prussian blue cathode material, conductive carbon, and binder are mixed and stirred in an oil-soluble solvent at a mass ratio of 6-8:1-3:1 to form a slurry; the slurry is coated on aluminum foil, dried in a vacuum oven overnight, and the aluminum foil with the Prussian blue slurry is compacted to obtain a Prussian blue target;

[0008] Step 2: preparing a benzoquinone solution: dissolving a benzoquinone substance in an organic solvent, performing ultrasonic treatment to obtain a benzoquinone solution, and pouring the benzoquinone solution into a feed chamber;

[0009] Step 3: Substrate pretreatment: Select a stainless steel substrate, clean it ultrasonically with a solvent, and then dry it. Fix the Prussian blue target obtained in step 1 on the substrate and place it in a deposition chamber.

[0010] Step 4: Set the pulsed laser deposition parameters: laser wavelength, pulse energy, deposition time, deposition chamber vacuum, substrate temperature, and then start deposition.

[0011] Step 5: Heat treatment: The deposited sample is heat treated in an inert atmosphere and cooled to room temperature to obtain a benzoquinone-coated Prussian blue composite material.

[0012] Furthermore, in step 1, the chemical formula of the Prussian blue powder is A x M1[M2 (CN)6 ] 1-y nH2O, wherein 1≤x≤2, 0≤y<1, 0<n≤3.5, A comprises Na and / or K, the M1 site comprises one or more of Sc, Ti, V, Cr, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb; the M2 site comprises one or more of Fe, Mn, Co and Ni; the conductive carbon comprises one or more of acetylene black, Super P, Ketjen black, carbon nanotube, graphene and carbon nanofiber; the binder comprises one or more of polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, sodium alginate and sodium polyacrylate; and the oil-soluble solvent comprises one or more of N-methylpyrrolidone, dimethylformamide and acetone.

[0013] Furthermore, in step one, the stirring time is 5h~15h, which can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15h; the thickness of the slurry coating is 50~200μm, which can be 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, or 200μm; the vacuum drying temperature is 100~200℃, which can be 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, or 200℃; the compaction treatment pressure is 2~20MPa, and the holding time is 0.2~2.0h. The pressure can be 2, 4, 6, 8, 10, 12, 14, 16, 18, 20 MPa; the holding time can be 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0 h.

[0014] Furthermore, in step 2, the benzoquinone substance is 1,4-benzoquinone (p-benzoquinone), 1,2-benzoquinone (o-benzoquinone), 2,6-di-tert-butyl-1,4-benzoquinone, 2,3,5,6-tetrachloro-1,4-benzoquinone, 2,3-dicyano-1,4-benzoquinone, 2,5-diamino-1,4-benzoquinone, tetrafluoro-1,4-benzoquinone, 2,5-dihydroxy-1,4-benzoquinone, 2,3,5,6-tetramethyl-1,4-benzoquinone, 2,5-diethyl-1,4-benzoquinone, 2,3-dibromo-1,4-benzoquinone, 2,3-dimethyl-1,4-benzoquinone. A combination of one or more of quinone, 2,5-dinitro-1,4-benzoquinone, 2,3,5,6-tetrabromo-1,4-benzoquinone, 2,5-dimethoxy-1,4-benzoquinone, 2,3-dihydroxy-1,4-benzoquinone, 2,5-diphenyl-1,4-benzoquinone, 2,3,5,6-tetracyano-1,4-benzoquinone, 2,5-dithiol-1,4-benzoquinone, and 2,3,5,6-tetramethoxy-1,4-benzoquinone; and the organic solvent is a combination of one or more of ethanol, methanol, isopropanol, acetonitrile, N,N-dimethylformamide, and dimethyl sulfoxide.

[0015] Furthermore, in step 2, the concentration of the benzoquinone solution is 0.01~0.1 g / ml, which can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.1 g / ml; and the ultrasonic treatment time is 10~40 min, which can be 10, 15, 20, 25, 30, 35, or 40 min.

[0016] Furthermore, in step three, the solvent is one or a combination of acetone, ethanol, ether, methanol, and deionized water; the cleaning time is 10-60 min, which can be 10, 20, 30, 40, 50, or 60 min; and the drying temperature is 50-150°C, which can be 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, or 150°C.

[0017] Furthermore, in step 4, the pulse laser deposition method: the wavelength is in the ultraviolet band, the pulse frequency is 1-10 Hz, which can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 Hz; the pulse energy is 200-300 mJ, which can be 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300 mJ; the deposition time is 2-12 h, which can be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 h; the vacuum degree is 1×10 -5 ~1×10 -3 Pa, which can be 1×10 -5 , 2×10 -5 , 3×10 -5 , 4×10 -5 , 5×10 -5 , 6×10 -5 , 7×10 -5 , 8×10 -5 , 9×10 -5 , 1×10 -4 , 2×10 -4 , 3×10 -4 , 4×10 -4 , 5×10 -4 , 6×10 -4 , 7×10 -4 , 8×10 -4 , 9×10 -4 , 1×10 -3 Pa; The substrate temperature is 100~200℃, which can be 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200℃.

[0018] Furthermore, in step five, the heat treatment temperature is 100-300° C., and may be 100, 150, 200, 250, or 300° C.; and the heat treatment time is 1-10 h, and may be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 h.

[0019] A benzoquinone substance-coated Prussian blue composite material prepared by the above preparation method has a core-shell structure, wherein the Prussian blue material is the core and the benzoquinone substance is the shell.

[0020] An alkali metal ion battery positive electrode comprises the above-mentioned benzoquinone-substance-coated Prussian blue composite material.

[0021] An alkali metal ion battery comprises the positive electrode.

[0022] The beneficial effects of the present invention compared to the prior art are:

[0023] 1. Uniform coating and controllable thickness: By precisely controlling reaction conditions such as reactant concentration, reaction time, and temperature, the surface of Prussian blue particles can be uniformly coated with benzoquinones and the thickness of the coating layer can be precisely controlled, thereby optimizing the electrochemical properties of the material.

[0024] 2. Strong binding and high stability: Benzoquinone substances are chemically bonded to the surface of Prussian blue, which is firmly bonded and not easy to fall off, thereby improving the cycle stability and service life of the material.

[0025] 3. Improve conductivity: Benzoquinone substances have good conductivity. When coated on the surface of Prussian blue, they can form a conductive network, thereby improving the overall conductivity of the material, reducing the internal resistance of the battery, and improving the rate performance.

[0026] 4. Inhibit side reactions: The benzoquinone coating layer can effectively inhibit the side reactions between Prussian blue and the electrolyte, reduce the dissolution of active substances and structural collapse, and improve the cycle stability of the material.

[0027] 5. Improve specific capacity: Benzoquinone substances themselves have certain electrochemical activity and can participate in redox reactions, providing additional specific capacity for the material.

[0028] 6. Improve rate performance: The coating layer of benzoquinone substances can improve the conductivity and ion diffusion rate of the material, thereby improving the rate performance of the material and enabling it to adapt to high-rate charge and discharge.

[0029] 7. The preparation process is simple and easy to scale up: This method has a simple process, is easy to operate, is easy to scale up, and has broad application prospects.

[0030] 8. Low cost and environmentally friendly: The raw materials used are cheap and widely available, and the preparation process does not require the use of expensive equipment or the production of harmful substances, and is environmentally friendly.

[0031] 9. Improve the structural stability of the material: The benzoquinone coating can effectively inhibit the volume expansion of Prussian blue during the charge and discharge process, improve the structural stability of the material, and extend the service life of the battery.

[0032] 10. Broaden the scope of application: The benzoquinone-coated Prussian blue material prepared by this method has excellent electrochemical properties and can be widely used in lithium-ion batteries, sodium-ion batteries, potassium-ion batteries and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a SEM image of the PBAs material synthesized in Example 1 of the present invention;

[0034] Figure 2 This is a rate performance diagram of the PBAs material synthesized in Example 1 of the present invention;

[0035] Figure 3 This is a cycle performance diagram of the PBAs material synthesized in Example 1 of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with specific examples, but the present invention is not limited to the following examples. The embodiments are only a part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0037] The present invention uses specific benzoquinones with unique molecular structures and electrochemical activity. These substances contain special functional groups that can specifically bind to the active sites on the surface of Prussian blue. Using chemical pulse deposition, the process parameters are precisely controlled to achieve uniform and controllable coating of the benzoquinones on the surface of Prussian blue particles, allowing the precursors of the benzoquinones to polymerize in situ on the surface of Prussian blue. This technology significantly improves the structural stability of Prussian blue, enhances electronic conductivity, and accelerates ion diffusion, thereby significantly improving the cycle performance, rate capability, and energy density of sodium-ion batteries. The preparation method is simple and controllable, and has the potential for large-scale industrial production.

[0038] Example 1:

[0039] Step 1, preparation of Prussian blue target: 0.28g Prussian blue (molecular formula: Na2FeFe(CN)6), 0.08g Ketjen black, 0.04g polyvinylidene fluoride were mixed in N-methylpyrrolidone solvent to form a slurry, stirred for 10h, coated on aluminum foil with a thickness of 100μm, and then dried in a vacuum oven at 120℃ overnight; the obtained Prussian blue slurry aluminum foil was pressurized at 10MPa for 0.2h to obtain the Prussian blue target (SEM image of the obtained material is shown in Figure 1). Figure 1 ).

[0040] Step 2: Prepare a 0.1 g / ml benzoquinone solution: dissolve 1 g of 1,4-benzoquinone in 10 mL of ethanol, ultrasonicate for 30 min to obtain a uniform benzoquinone solution, and then pour the solution into the feed chamber.

[0041] Step 3: Substrate pretreatment: Select a stainless steel substrate, clean it ultrasonically with acetone for 10 minutes, and dry it at 100° C. Fix the Prussian blue target obtained in step 1 on the substrate and place it in a deposition chamber.

[0042] Step 4. Pulsed laser deposition parameters: laser wavelength: 248 nm (KrF excimer laser); pulse energy: 200 mJ; pulse frequency: 10 Hz; deposition time: 2 h; deposition chamber vacuum: 1×10 -4 Pa; substrate temperature: 200°C, and then deposition begins.

[0043] Step 5: Heat treatment: The deposited sample was heat treated at 200° C. for 2 h under a nitrogen atmosphere to obtain a Prussian blue composite material coated with benzoquinone substances.

[0044] Example 2:

[0045] Step 1. Preparation of Prussian blue target: 0.28g of Prussian blue (molecular formula: Na2MnFe(CN)6), 0.08g of acetylene black, and 0.04g of polyvinylidene fluoride are mixed in N-methylpyrrolidone solvent to form a slurry, stirred for 10 hours, coated on aluminum foil with a thickness of 120μm, and then dried in a vacuum oven at 150°C overnight; the obtained Prussian blue slurry aluminum foil is pressurized at 15MPa for 0.4h to obtain the Prussian blue target.

[0046] Step 2: Prepare 0.2 g / ml benzoquinone solution: Dissolve 2 g of 2,6-di-tert-butyl-1,4-benzoquinone in 10 mL of isopropanol, sonicate for 30 min to obtain a uniform benzoquinone solution, and then pour the solution into the feed chamber.

[0047] Step 3: Substrate pretreatment: same as in Example 1.

[0048] Step 4: Pulsed laser deposition parameters: laser wavelength: 248 nm; pulse energy: 250 mJ; pulse frequency: 15 Hz; deposition time: 45 minutes; deposition chamber vacuum: 5×10 -5 Pa; substrate temperature: 190°C, and then deposition began.

[0049] Step 5: Heat treatment: The deposited sample was heat treated at 250°C for 3 hours in a nitrogen atmosphere.

[0050] Example 3:

[0051] Step 1. Preparation of Prussian blue target: 0.28g of Prussian blue (molecular formula: Na2CoFe(CN)6), 0.08g of carbon nanotubes, and 0.04g of sodium alginate are mixed in N-methylpyrrolidone solvent to form a slurry, stirred for 12 hours, coated on aluminum foil with a thickness of 130μm, and then dried in a vacuum oven at 150°C overnight; the obtained Prussian blue slurry aluminum foil is pressurized at 15MPa for 0.4h to obtain the Prussian blue target.

[0052] Step 2: Prepare 0.3 g / ml benzoquinone solution: dissolve 3 g of 2,3,5,6-tetramethyl-1,4-benzoquinone in 10 mL of N-methylpyrrolidone, ultrasonicate for 40 min to obtain a uniform benzoquinone solution, and then pour the solution into the feed chamber.

[0053] Step 3: Substrate pretreatment: same as in Example 1.

[0054] Step 4: Pulsed laser deposition parameters: laser wavelength: 248 nm; pulse energy: 300 mJ; pulse frequency: 20 Hz; deposition time: 60 minutes; deposition chamber vacuum: 1×10 -5 Pa; substrate temperature: 180°C, and then deposition began.

[0055] Step 5: Heat treatment: Heat the deposited sample at 300° C. for 4 hours in a nitrogen atmosphere.

[0056] Example 4:

[0057] Step 1: Preparation of Prussian blue target: 0.28g of Prussian blue (molecular formula: Na2Mn 0.2 Fe 0.8 Fe(CN)6), 0.08g of graphene, and 0.04g of sodium alginate were mixed in N-methylpyrrolidone solvent to form a slurry, stirred for 10 hours, coated on aluminum foil with a thickness of 50μm, and then dried in a vacuum oven at 150°C overnight; the obtained Prussian blue slurry aluminum foil was pressurized at 2MPa for 0.2h to obtain the Prussian blue target.

[0058] Step 2: Prepare 0.4 g / ml benzoquinone solution: dissolve 4 g of 2,3,5,6-tetrachloro-1,4-benzoquinone in 10 mL of ethanol, ultrasonicate for 30 min to obtain a uniform benzoquinone solution, and then pour the solution into the feed chamber.

[0059] Step 3: Substrate pretreatment: same as in Example 1.

[0060] Step 4: Pulsed laser deposition parameters: laser wavelength: 248 nm; pulse energy: 220 mJ; pulse frequency: 12 Hz; deposition time: 40 minutes; deposition chamber vacuum: 2×10-4 Pa; substrate temperature: 170°C, and then deposition began.

[0061] Step 5: Heat treatment: Heat the deposited sample at 100° C. for 2 h in a nitrogen atmosphere.

[0062] Example 5:

[0063] Step 1: Preparation of Prussian blue target: 0.28g of Prussian blue (molecular formula: Na2Mn 0.8 Fe 0.2 Fe(CN)6), 0.08g Super P, and 0.04g sodium polymethacrylate were mixed in N-methylpyrrolidone solvent to form a slurry, stirred for 15h, coated on aluminum foil with a thickness of 200μm, and then dried in a vacuum oven at 150℃ overnight; the obtained Prussian blue slurry aluminum foil was pressurized at 10 MPa for 2h to obtain the Prussian blue target.

[0064] Step 2: Prepare 0.5 g / ml benzoquinone solution: dissolve 5 g 1,4-benzoquinone in 10 mL isopropanol and sonicate for 30 min to obtain a uniform benzoquinone solution. Then pour the solution into the feed chamber.

[0065] Step 3: Substrate pretreatment: same as in Example 1.

[0066] Step 4: Pulsed laser deposition parameters: laser wavelength: 248 nm; pulse energy: 280 mJ; pulse frequency: 18 Hz; deposition time: 50 minutes; deposition chamber vacuum: 3×10 -5 Pa; substrate temperature: 150°C, and then deposition began.

[0067] Step 5: Heat treatment: Heat the deposited sample at 150° C. for 3 h in a nitrogen atmosphere.

[0068] Example 6:

[0069] Step 1: Preparation of Prussian blue target: same as in Example 1.

[0070] Step 2: Prepare 0.4 g / ml benzoquinone solution: dissolve 3 g 1,4-benzoquinone in 7.5 mL ethanol and ultrasonicate for 30 min to obtain a uniform benzoquinone solution, then pour the solution into the feed chamber.

[0071] Step 3: Substrate pretreatment: same as in Example 1.

[0072] Step 4: Pulsed laser deposition parameters: laser wavelength: 248 nm; pulse energy: 230 mJ; pulse frequency: 11 Hz; deposition time: 35 minutes; deposition chamber vacuum: 5×10 -4Pa; substrate temperature: 160°C, and then deposition began.

[0073] Step 5: Heat treatment: The deposited sample was heat treated at 210° C. for 2.2 hours in a nitrogen atmosphere.

[0074] Example 7:

[0075] Step 1: Preparation of Prussian blue target: same as in Example 2.

[0076] Step 2: Prepare 0.1 g / ml benzoquinone solution: dissolve 2.5 g of 2,6-di-tert-butyl-1,4-benzoquinone in 25 mL of isopropanol, ultrasonicate for 60 min to obtain a uniform benzoquinone solution, and then pour the solution into the feed chamber.

[0077] Step 3: Substrate pretreatment: same as in Example 1.

[0078] Step 4: Pulsed laser deposition parameters: laser wavelength: 248 nm; pulse energy: 270 mJ; pulse frequency: 16 Hz; deposition time: 55 minutes; deposition chamber vacuum: 4×10 -5 Pa; substrate temperature: 150°C, and then deposition began.

[0079] Step 5: Heat treatment: The deposited sample was heat treated at 270° C. for 3.2 hours in a nitrogen atmosphere.

[0080] Example 8:

[0081] Step 1: Preparation of Prussian blue target: same as in Example 3.

[0082] Step 2: Prepare benzoquinone solution: dissolve 3.5 g of 2,3,5,6-tetramethyl-1,4-benzoquinone in 5 mL of N-methylpyrrolidone, and ultrasonicate for 30 minutes to obtain a uniform benzoquinone solution, which is then poured into the feed chamber.

[0083] Step 3: Substrate pretreatment: same as in Example 1.

[0084] Step 4: Pulsed laser deposition parameters: laser wavelength: 248 nm; pulse energy: 290 mJ; pulse frequency: 19 Hz; deposition time: 65 minutes; deposition chamber vacuum: 5×10 -5 Pa; substrate temperature: 140°C, and then deposition began.

[0085] Step 5: Heat treatment: The deposited sample was heat treated at 290° C. for 3.8 hours in a nitrogen atmosphere.

[0086] Example 9:

[0087] Step 1: Preparation of Prussian blue target: same as in Example 4.

[0088] Step 2: Preparation of benzoquinone solution: Dissolve 4.5 g of 2,3,5,6-tetrachloro-1,4-benzoquinone in 50 mL of ethanol and ultrasonicate for 30 minutes to obtain a uniform benzoquinone solution, which is then poured into the feed chamber.

[0089] Step 3: Substrate pretreatment: same as in Example 1.

[0090] Step 4: Pulsed laser deposition parameters: laser wavelength: 248 nm; pulse energy: 240 mJ; pulse frequency: 13 Hz; deposition time: 42 minutes; deposition chamber vacuum: 3×10 -4 Pa; substrate temperature: 130°C, and then deposition began.

[0091] Step 5: Heat treatment: The deposited sample was heat treated at 230° C. for 2.8 hours in a nitrogen atmosphere.

[0092] The electrodes obtained above were cut into 14 mm diameter circular pieces, which contained about 1.5 mg cm -2 Active material loading. CR2032 button cells were assembled in an Ar-filled glove box (O2<0.01ppm, H2O<0.01pm). The prepared working electrode used Na foil as the negative electrode, 1 mol / L sodium perchlorate, EC:PC volume ratio of 1:1, and 5% FEC as the electrolyte (the electrochemical performance of the material obtained in Example 1 is shown in Figure 2 and Figure 3 ).

[0093] Tested at room temperature, after three cycles of activation at 0.1C rate, and 600 cycles at 1C rate, the following data were obtained:

[0094]

Claims

1. A method for preparing a composite material of Prussian blue coated with a benzoquinone substance, characterized in that: The method is: Step 1: Preparation of a Prussian blue target: Prussian blue cathode material, conductive carbon, and binder are mixed and stirred in an oil-soluble solvent at a mass ratio of 6-8:1-3:1 to form a slurry; the slurry is coated on aluminum foil, dried in a vacuum oven overnight, and the aluminum foil with the Prussian blue slurry is compacted to obtain a Prussian blue target; Step 2: preparing a benzoquinone solution: dissolving a benzoquinone substance in an organic solvent, performing ultrasonic treatment to obtain a benzoquinone solution, and pouring the benzoquinone solution into a feed chamber; Step 3: Substrate pretreatment: Select a stainless steel substrate, clean it ultrasonically with a solvent, and then dry it. Fix the Prussian blue target obtained in step 1 on the substrate and place it in a deposition chamber. Step 4: Set the pulsed laser deposition parameters: laser wavelength, pulse energy, deposition time, deposition chamber vacuum, substrate temperature, and then start deposition. Step 5: Heat treatment: The deposited sample is heat treated in an inert atmosphere and cooled to room temperature to obtain a benzoquinone-coated Prussian blue composite material.

2. The preparation method according to claim 1, wherein: In step 1, the chemical formula of the Prussian blue powder is A x M1[M2 (CN)6 ] 1-y nH2O, wherein 1≤x≤2, 0≤y<1, 0<n≤3.5, A comprises Na and / or K, the M1 site comprises one or more of Sc, Ti, V, Cr, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb; the M2 site comprises one or more of Fe, Mn, Co and Ni; the conductive carbon comprises one or more of acetylene black, Super P, Ketjen black, carbon nanotube, graphene and carbon nanofiber; the binder comprises one or more of polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, sodium alginate and sodium polyacrylate; and the oil-soluble solvent comprises one or more of N-methylpyrrolidone, dimethylformamide and acetone.

3. The preparation method according to claim 1, wherein: In step 1, the stirring time is 5 h to 15 h; the thickness of the slurry coating is 50 to 200 μm; the temperature of the vacuum drying is 100 to 200° C.; the pressure of the compaction treatment is 2 to 20 MPa, and the holding time is 0.2 to 2.0 h.

4. The preparation method according to claim 1, wherein: In step 2, the benzoquinone substances are 1,4-benzoquinone (p-benzoquinone), 1,2-benzoquinone (o-benzoquinone), 2,6-di-tert-butyl-1,4-benzoquinone, 2,3,5,6-tetrachloro-1,4-benzoquinone, 2,3-dicyano-1,4-benzoquinone, 2,5-diamino-1,4-benzoquinone, tetrafluoro-1,4-benzoquinone, 2,5-dihydroxy-1,4-benzoquinone, 2,3,5,6-tetramethyl-1,4-benzoquinone, 2,5-diethyl-1,4-benzoquinone, 2,3-dibromo-1,4-benzoquinone, 2,3-dimethyl-1,4-benzoquinone, A combination of one or more of 2,5-dinitro-1,4-benzoquinone, 2,3,5,6-tetrabromo-1,4-benzoquinone, 2,5-dimethoxy-1,4-benzoquinone, 2,3-dihydroxy-1,4-benzoquinone, 2,5-diphenyl-1,4-benzoquinone, 2,3,5,6-tetracyano-1,4-benzoquinone, 2,5-dithiol-1,4-benzoquinone, and 2,3,5,6-tetramethoxy-1,4-benzoquinone; and the organic solvent is a combination of one or more of ethanol, methanol, isopropanol, acetonitrile, N,N-dimethylformamide, and dimethyl sulfoxide.

5. The preparation method according to claim 1, wherein: In step 2, the concentration of the benzoquinone solution is 0.01-0.1 g / ml; and the ultrasonic treatment time is 10-40 min.

6. The preparation method according to claim 1, wherein: In step 3, the solvent is one or a combination of acetone, ethanol, ether, methanol, and deionized water; the cleaning time is 10 to 60 minutes; and the drying temperature is 50 to 150°C.

7. The preparation method according to claim 1, wherein: In step 4, the pulse laser deposition method: the wavelength is in the ultraviolet band, the pulse frequency is 1-10 Hz; the pulse energy is 200-300 mJ; the deposition time is 2-12 h; the vacuum degree is 1×10 -5 ~1×10 -3 Pa; substrate temperature is 100~200℃.

8. The preparation method according to claim 1, wherein: In step 5, the heat treatment temperature is 100-300° C. and the time is 1-10 h.

9. A benzoquinone-based substance-coated Prussian blue composite material prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The material has a core-shell structure, wherein the Prussian blue material is the core and the benzoquinone material is the shell.

10. An alkali metal ion battery positive electrode, characterized in that: The positive electrode comprises the Prussian blue composite material coated with a benzoquinone substance according to claim 9.

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