Hollow multi-shell artificial solid electrolyte interfacial film and preparation method and application thereof

Abstract

The invention relates to the technical field of functional materials, in particular to a hollow multi-shell artificial solid electrolyte interface (SEI) membrane as well as a preparation method and application thereof. Comprising the following steps: 1) carrying out a heating reaction on a carbon source aqueous solution to obtain a carbon sphere template; 2) dispersing the carbon sphere template obtained in the step 1) in a metal salt precursor solution, and performing suction filtration, washing and calcining to prepare a metal oxide hollow multi-shell layer; (3) reducing the metal oxide obtained in the step (2) into a metal simple substance, and standing in a constant-temperature and constant-humidity environment to oxidize the surface of the metal simple substance, so as to obtain a metal-metal oxide composite hollow multi-shell layer; and 4) coating a metal foil electrode with the metal-metal oxide composite hollow multi-shell layer obtained in the step 3) by adopting a spin-coating method, and performing auxiliary heating or air blowing during spin-coating to obtain the artificial SEI film. The artificial SEI film gives consideration to both local strong mechanical properties and overall flexibility, effectively inhibits the growth of lithium dendrites in the lithium battery, and improves the coulombic efficiency and cycle life of the battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional materials, and in particular, relates to a hollow multi-shell artificial solid electrolyte interface membrane and a preparation method and application thereof. Background Art

[0002] The energy and environmental crisis is a prominent global challenge at present. The development and utilization of new energy sources such as solar energy, wind energy, and tidal energy are expected to solve / alleviate this crisis. However, due to the general characteristics of randomness and volatility of new energy sources, their large-scale application scope is limited. Energy storage technology represented by secondary batteries is a key supporting technology to promote the large-scale application of new energy. Although lithium-ion batteries have been widely used in many fields, their energy density has approached the theoretical value of existing electrode materials, which is difficult to meet people's needs.

[0003] As the negative electrode of lithium batteries, lithium metal has the highest theoretical energy density (3860mAh / g) and the lowest redox potential (3.04V vs.SHE), and is considered to be one of the most promising negative electrode materials for lithium batteries. However, the high chemical activity of lithium metal makes it easy to react with organic electrolytes, consume electrolytes, and form a large amount of solid electrolyte interface (SEI), resulting in a short battery cycle life. In addition, lithium metal tends to grow in dendrites, and lithium dendrites can easily pierce the diaphragm and cause internal short circuits in the battery, thus posing serious safety hazards to the battery.

[0004] At present, people have developed a variety of modification methods to improve the performance of lithium metal batteries, such as constructing a lithium metal deposition skeleton, adding additives to the electrolyte, or using solid electrolytes. Although these modification methods have improved the performance of lithium metal batteries to a certain extent, it is difficult to balance the coulombic efficiency, cycle life, rate performance and safety of the battery, and lithium metal batteries have not yet been able to achieve large-scale commercial use. Summary of the invention

[0005] The purpose of the present invention is to provide a hollow multi-shell artificial solid electrolyte interface (SEI) membrane and its preparation method and application, that is, to provide a new artificial SEI membrane for solving problems such as lithium dendrite growth in lithium metal batteries to improve the performance of lithium metal batteries.

[0006] On the one hand, the present invention aims at the problem of lithium dendrite growth in lithium metal batteries, and constructs an inorganic-organic composite artificial SEI membrane. The SEI membrane is composed of an inorganic hollow multi-shell and an organic binder, and the metal-metal oxide composite hollow multi-shell has good chemical and electrochemical stability, and the surface metal oxide is conducive to combining with the functional groups in the binder. The two together give the artificial SEI membrane a strong mechanical stability against lithium dendrite piercing and overall anti-bending flexibility, so that the artificial SEI membrane can float on the water like a lotus leaf, on the lithium metal, and always remain stable. On the other hand, in response to the demand for fast charging performance of lithium metal batteries, an artificial SEI membrane based on a hollow multi-shell structure metal-metal oxide composite is designed. The metal can provide good electronic conductivity, while the metal oxide can conduct lithium ions. Multiple composite hollow multi-shell balls constitute a three-dimensional mass transfer channel, which can effectively reduce the local current density and improve the fast charging performance of the battery.

[0007] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0008] In the first aspect of the present invention, the present invention provides a method for preparing a hollow multi-shell artificial SEI membrane material, comprising the following steps:

[0009] 1) Preparation of carbon sphere template: placing a carbon source aqueous solution in a reaction kettle, heating to obtain micro-nano sized colloidal carbon spheres, and filtering, washing and drying to obtain a carbon sphere template;

[0010] 2) preparing a metal oxide hollow multi-shell layer: dispersing the carbon sphere template obtained in step 1) in a metal ion solution, stirring, heat-insulating and adsorbing the obtained suspension, and then filtering, washing, drying and calcining to obtain a metal oxide hollow multi-shell layer;

[0011] 3) reducing the metal oxide hollow multi-shell obtained in step 2) to a metal hollow multi-shell. Then the solid is allowed to stand in a constant temperature and humidity environment for a certain period of time to oxidize the solid surface and obtain a metal-metal oxide composite hollow multi-shell. The thickness of the metal oxide on the shell wall surface and the ratio of the metal to the metal oxide can be controlled by controlling the temperature, humidity, time, etc. of the standing in a constant temperature and humidity environment;

[0012] 4) Adding a binder and a dispersing solvent to the composite hollow multi-shell layer in step 3) to grind into a slurry, using a slurry machine to spin coat, applying the slurry to the electrode surface, and drying to obtain an electrode carrying an artificial SEI film. The slurry is evenly coated on the surface of the metal foil by auxiliary heating and blowing during the spin coating process, and the thickness of the artificial SEI film is regulated by controlling the rotation speed, slurry viscosity, ambient temperature, ambient humidity and other conditions.

[0013] By adopting the preparation method of the present invention, a metal-metal oxide composite hollow multi-shell material can be prepared by designing a method for controlled surface oxidation of metal hollow multi-shells. And by designing a spin coating method, auxiliary heating and blowing treatment strategies, an artificial SEI membrane with a hollow multi-shell structure is prepared. The preparation method has mild conditions, simple operation, and is suitable for large-scale production, and the structural parameters, membrane thickness, etc. are controllable. The prepared artificial SEI membrane is used in energy storage batteries, and has the functions of high ion permeability, uniform ion flow, and inhibition of lithium dendrites, which can greatly improve the life and performance of the battery.

[0014] The preparation method according to the present invention may also have the following additional technical features:

[0015] The carbon source in step 1) includes one or a combination of two or more of glucose, fructose, sucrose, maltose, starch and citric acid. The concentration of the carbon source aqueous solution is 0.1-5M, and the hydrothermal reaction temperature is 160-220°C.

[0016] The metal oxide in step 2) includes one or a combination of two or more of copper oxide, cobalt oxide, nickel oxide, iron oxide, manganese oxide, titanium oxide, etc.

[0017] In step 3), the reducing agent is sodium borohydride, potassium borohydride, sodium bisulfite, ammonia, hydrogen or carbon monoxide, and the reduction temperature is 25-500° C.;

[0018] In the step 3), the temperature of the metal single substance hollow multi-shell layer in a constant temperature and humidity environment is 25-100° C., the humidity is 10-60%, and the standing time is 8-24 hours; the metal-metal oxide composite hollow multi-shell layer is one or a combination of two or more of copper-cuprous oxide, copper-cupric oxide, cobalt-cobalt oxide, iron-ferroferric oxide, nickel-nickel oxide, manganese-manganese oxide, titanium-titanium oxide, etc.

[0019] In the step 4), the binder includes one or a combination of two or more of polyvinylidene fluoride, polyethylene, polypropylene, and ethyl cellulose; the dispersant includes one or a combination of two or more of ethanol, acetone, terpineol, pyridine, tetrahydrofuran, and ethylene glycol methyl ether; the mass ratio of the hollow multi-shell layer, the binder, and the dispersant is 1:(0.01-5):(1-10), and the grinding time is 0.5-1h.

[0020] During the spin coating in step 4), the speed of the coating machine is 1000-9000 r / min; the spin coating time is 10-60 s; the amount of the spin coating slurry is 0.1-1 mL / cm 2 ; The number of spin coating times is 1-3 times; The heating temperature for spin coating is 25-80°C, and the air flow velocity is 10-25m / s; The metal foil can be copper foil, nickel foil, titanium foil, stainless steel foil, etc.

[0021] The second aspect of the present invention provides a hollow multi-shell artificial SEI membrane material.

[0022] The hollow multi-shell artificial SEI membrane material is prepared by the method described in the first aspect. The artificial SEI membrane is a composite membrane of hollow multi-shells and a binder, with a thickness of 1-30 microns, the composite hollow multi-shells inside are evenly distributed, and the shell wall of the hollow multi-shells is 1-4 layers.

[0023] Metal-metal oxide composite hollow multi-shell, metal has good electronic conductivity, and the surface oxide is not only conducive to guiding the uniform transmission of lithium ions, reducing local current, and reducing lithium dendrites, but also can combine with the functional groups in the binder to improve the overall mechanical stability of the artificial SEI film.

[0024] The hollow multi-shell artificial SEI membrane of the present invention is used in lithium metal batteries and significantly improves the coulombic efficiency and cycle life of the lithium metal batteries.

[0025] The third aspect of the present invention provides the use of the hollow multi-shell artificial SEI membrane material as described in the first aspect in the field of lithium batteries.

[0026] The present invention provides a lithium metal battery negative electrode, wherein the lithium negative electrode is modified with the artificial SEI film of the present invention to inhibit the growth of lithium dendrites and reduce the local current density, thereby significantly improving the coulombic efficiency, cycle life and safety of the battery.

[0027] Compared with the prior art, the advantages of the present invention are:

[0028] 1) The main material of the artificial SEI membrane described in the present invention is a metal-metal oxide composite hollow multi-shell structure material. The metal hollow multi-shell is first reduced by design, and then left to stand for a certain period of time in a constant temperature and humidity environment so that the surface of the multi-shell is oxidized. The thickness of the metal oxide on the surface of the shell wall and the ratio of metal to metal oxide can be precisely controlled. The internal metal multi-shell can quickly conduct electrons and reduce local current, while the surface metal oxide can not only guide the uniform distribution of lithium ions during the transmission process, reduce local current, and reduce lithium dendrites, but also can combine with the functional groups in the binder to improve the overall mechanical stability of the artificial SEI membrane;

[0029] 2) Spin coating is used to coat the hollow multi-shell layer on the metal foil to obtain an artificial SEI film. By auxiliary heating and blowing during the spin coating process, the slurry can be evenly coated on the surface of the metal foil, and the thickness of the artificial SEI film can be accurately controlled by controlling the rotation speed, slurry viscosity, ambient temperature, ambient humidity and other conditions. The thickness of the artificial SEI film can be controlled at 1-30 microns. Preferably, the present invention controls the thickness of the artificial film to 1-2 microns. The thin artificial SEI film reduces the mass of inactive materials and is conducive to obtaining a higher battery energy density.

[0030] 3) The artificial SEI film is an organic-inorganic composite film. The inorganic part has high mechanical strength and can resist puncture by lithium dendrites; the organic part provides flexibility for the SEI film as a whole. Using this artificial SEI film as a lithium metal negative electrode can significantly improve battery performance and life. The battery has been tested for a long cycle, 1mA / cm 2 When the negative electrode is combined with NCM811 to form a full battery, the capacity can still be maintained at more than 160mAh / g after 100 cycles at 1C current. As a lithium metal negative electrode, the performance is far superior to that of nanoparticles of the same component or a negative electrode without any material loading. The negative electrode is combined with NCM811 to prepare a soft-pack battery, which can operate normally for more than 40 cycles, indicating its potential for commercial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a transmission electron microscope photograph of the copper oxide hollow multi-shell in Example 1 of the present invention;

[0032] Figure 2 This is a transmission electron microscope photograph of the copper-cuprous oxide composite hollow multi-shell structure of Example 1 of the present invention;

[0033] Figure 3 is an X-ray diffraction pattern of the copper oxide hollow multi-shell in Example 1 of the present invention;

[0034] Figure 4 is the X-ray diffraction pattern of the copper-cuprous oxide composite hollow multi-shell of Example 1 of the present invention;

[0035] Figure 5 is a scanning electron microscope photograph of a cross section of an electrode having an artificial SEI film on a copper foil substrate according to Example 1 of the present invention;

[0036] Figure 6 The electrode with artificial SEI film in Example 1 of the present invention is embedded with 2 mAh / cm 2 Scanning electron microscope photo of the cross section of lithium metal;

[0037] Figure 7 4 is a diagram of the coulombic efficiency of the battery during the cycle of Example 1 of the present invention. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with specific embodiments.

[0039] The present invention provides a method for preparing a hollow multi-shell artificial SEI membrane, the method comprising:

[0040] (a) A carbon source aqueous solution with a concentration of 0.1-5 M is placed in a hydrothermal reactor at 160-220° C. for hydrothermal reaction for 2-3 hours. After cooling, the carbon sphere template is obtained by suction filtration and drying.

[0041] (b) dispersing the carbon sphere template obtained in step a) in a metal ion solution, wherein the metal salt is one or a combination of two or more selected from acetate, chloride, nitrate, and sulfate, and the metal ion concentration is 0.01-3 mol / L. The carbon sphere template adsorbs the metal ions, and then undergoes suction filtration, washing, drying, and calcination to obtain a hollow multi-shell metal oxide. The prepared metal oxide includes one or a combination of two or more selected from copper oxide, cobalt oxide, nickel oxide, iron oxide, manganese oxide, titanium oxide, and the like.

[0042] (c) reducing the metal oxide hollow multi-shell obtained in step b) to a metal element hollow multi-shell with a reducing agent, wherein the reducing agent is sodium borohydride, potassium borohydride, sodium bisulfite, ammonia, hydrogen or carbon monoxide, at a reduction temperature of 25-500° C. and a reduction time of 30-180 min.

[0043] The temperature of the metal single substance hollow multi-shell layer in a constant temperature and humidity environment is 25-100°C, the humidity is 10-60%, and the standing time is 8-24h; the metal-metal oxide composite hollow multi-shell layer is one or a combination of two or more of copper-cuprous oxide, copper-copper oxide, cobalt-cobalt oxide, iron-ferroferric oxide, nickel-nickel oxide, manganese-manganese oxide, titanium-titanium oxide, etc.

[0044] (d) adding a binder and a dispersing solvent to the metal-metal oxide composite hollow multi-shell layer in step c) and grinding into a slurry, wherein the binder is one or a combination of two or more of polyvinylidene fluoride, polyethylene, polypropylene, and ethyl cellulose, and the dispersant is one or a combination of two or more of ethanol, acetone, terpineol, pyridine, tetrahydrofuran, and ethylene glycol methyl ether. The mass ratio of the hollow multi-shell layer, the binder, and the dispersant is 1: (0.01-5): (1-10), and the grinding time is 0.5-1h;

[0045] The slurry in step d) is heated at 0.1-1 mL / cm 2The amount is evenly applied on the electrode substrate, wherein the substrate can be a metal foil surface, and the metal foil can be copper foil, nickel foil, titanium foil, stainless steel foil, etc. The spin coating speed is 1000-9000r / min, the spin coating time is 10-60s; the spin coating number is 1-3 times; the spin coating heating temperature is 25-80℃, and the air flow velocity is 10-25m / s.

[0046] The spin-coated substrate is dried under vacuum at a temperature of 50-100° C. for 8-24 hours to obtain an electrode with an artificial interface film.

[0047] Example 1

[0048] A preparation method and application of a hollow multi-shell artificial SEI membrane, the method comprising:

[0049] (1) A 1 M sucrose aqueous solution was placed in a hydrothermal reactor at 200° C. for hydrothermal reaction for 2 h. After cooling, the carbon sphere template was obtained by filtration and drying. The drying conditions were: 50° C. for 8 h.

[0050] (2) The carbon sphere template obtained in step (1) is dispersed in a copper acetate solution, and the concentration of copper acetate is 0.01 mol / L. The carbon sphere template adsorbs copper ions for 15 hours at a temperature of 25° C. After filtration, washing, drying, and muffle furnace calcination, a copper oxide hollow multi-shell sphere with 2 shells is obtained.

[0051] (3) The copper oxide hollow multi-shell layer described in step (2) is dispersed in a sodium borohydride aqueous solution with a concentration of 0.05M, and the reaction occurs at room temperature for 2 hours. After the reaction is completed, the solid is filtered and washed 3 times, and dried at 50°C for 8 hours to obtain the copper hollow multi-shell layer.

[0052] (4) The copper hollow multi-shell layer is placed in a constant temperature and humidity chamber at 25° C. and a humidity of 10% for 8 h to obtain a copper-cuprous oxide composite hollow multi-shell layer.

[0053] (5) The hollow multi-shell, polyvinylidene fluoride, and terpineol were mixed in a mass ratio of 1:0.05:10, and ground for 0.5 h to obtain a slurry with moderate viscosity. The slurry was heated at 0.1 mL / cm 2 The amount of the coating was evenly coated on the copper foil substrate, the spin coating speed was 1000r / min, the spin coating time was 10s; the spin coating was carried out at a temperature of 25°C, and the blowing air flow rate was 10m / s. The spin-coated electrode was dried in a vacuum state at a drying temperature of 100°C. After drying for 8 hours, an electrode covered with an artificial SEI film was obtained, and the thickness of the artificial SEI film was about 2 microns.

[0054] (6) The electrode with the artificial SEI film in step (5) was cut into a circular electrode sheet with a diameter of 12 mm as the working electrode of the battery, and a lithium sheet with a diameter of 14 mm was used as the counter electrode. The two electrodes were separated by a 19 mm diaphragm, and 60 μl of electrolyte (solute is 1 M lithium bistrifluoromethanesulfonyl imide, solvent is dioxolane:ethylene glycol dimethyl ether = 1:1) was added to assemble into a button cell. The battery was subjected to a battery long cycle test under the conditions of a current of 1 mA and a charge / discharge capacity of 1 mh.

[0055] The transmission electron microscopy photos of the obtained copper oxide hollow multi-shell are shown in Figure 1 As shown, it is a two-layer hollow sphere. The electron microscope photo of the copper hollow multi-shell obtained after reduction is shown in Figure 2 As shown. It can be seen that the morphology and structure of the hollow spheres did not change significantly after reduction. The X-ray diffraction of the copper oxide hollow spheres and the copper-cuprous oxide hollow multi-shells are shown as follows: Figure 3 , Figure 4 The scanning electron microscope photo of the electrode cross section after spin coating is shown in Figure 5 As shown in the figure, it can be seen that the structure of the artificial interface film is uniform and the thickness is 1-2 microns. The cross-sectional scanning electron micrograph of the electrode after lithium insertion is shown in the figure. Figure 6 As shown in the figure, the sandwich structure of substrate-lithium metal-artificial SEI film is shown, and the artificial SEI film shows a "lotus leaf" effect on lithium metal. Figure 7 As shown, 1mA / cm 2 After 500 cycles of cycling with a current of , the coulombic efficiency of the battery with an artificial SEI film was still maintained at 99.5%. Obviously, its cycle life and coulombic efficiency are better than those of the battery without an artificial SEI film.

[0056] Example 2

[0057] A method for preparing an artificial SEI film, the method comprising:

[0058] (1) A 0.1 M sucrose aqueous solution was placed in a hydrothermal reactor at 180° C. for hydrothermal reaction for 2 h. After cooling, the carbon sphere template was obtained by filtration and drying. The drying conditions were: 50° C. for 12 h.

[0059] (2) The carbon sphere template obtained in step (1) is dispersed in an iron nitrate solution, wherein the concentration of the iron nitrate is 1.0 mol / L. The carbon sphere template adsorbs iron ions for 8 hours at a temperature of 40° C. After filtration, washing, drying, and muffle furnace calcination, a hollow multi-shell iron oxide sphere is obtained, wherein the number of shells is 3.

[0060] (3) The iron oxide hollow multi-shell layer described in step (2) is reduced by carbon monoxide at a reduction temperature of 500° C. for a reaction time of 3 h to obtain an iron hollow multi-shell layer.

[0061] (4) The iron hollow multi-shell layer is placed in a constant temperature and humidity chamber at 60° C. and 30% humidity for 24 hours to obtain an iron-ferroferric oxide composite hollow multi-shell layer.

[0062] (5) The composite hollow multi-shell, ethyl cellulose, and terpineol + ethylene glycol methyl ether (1:1) in step (4) are mixed in a mass ratio of 1:1:1, and ground for 1 hour to obtain a slurry with moderate viscosity. The slurry is heated at 0.5 mL / cm 2 The amount of the slurry was evenly applied on the nickel foil substrate. The nickel foil coated with the slurry was spin-coated using a coating machine, the spin-coating speed was 5000r / min, and the spin-coating time was 30s; the spin-coating was carried out at a temperature of 25°C and the air flow rate was 10m / s. The spin-coated electrode was dried under vacuum at a drying temperature of 80°C. After drying for 12 hours, an electrode covered with an artificial SEI film was obtained, and the thickness of the artificial SEI film was about 6 microns.

[0063] Example 3

[0064] A method for preparing an artificial SEI film, the method comprising:

[0065] (1) A 5M aqueous glucose solution was placed in a hydrothermal reactor at 200°C for hydrothermal reaction for 3 hours. After cooling, the carbon sphere template was obtained by filtration and drying. The drying conditions were: 70°C for 24 hours.

[0066] (2) The carbon sphere template obtained in step (1) is dispersed in a nickel chloride solution, wherein the nickel chloride concentration is 3.0 mol / L. The carbon sphere template adsorbs nickel ions for 24 hours at a temperature of 40° C. After filtration, washing, drying, and muffle furnace calcination, a hollow multi-shell nickel oxide is obtained, wherein the number of shells is 4.

[0067] (3) The nickel oxide hollow multi-shell layer described in step (2) is reduced by hydrogen at a reduction temperature of 500° C. for a reaction time of 2 h to obtain a nickel hollow multi-shell layer.

[0068] (4) The nickel hollow multi-shell layer is placed in a constant temperature and humidity chamber at 100° C. and 60% humidity for 24 hours to obtain a nickel-nickel oxide composite hollow multi-shell layer.

[0069] (5) The composite hollow multi-shell, polypropylene and tetrahydrofuran in step (3) are mixed in a mass ratio of 1:0.5:5, and ground for 1 hour to obtain a slurry with moderate viscosity. The slurry is heated at 1 mL / cm 2The amount of the slurry was evenly applied on the titanium foil substrate. The titanium foil coated with the slurry was spin-coated using a coating machine, the spin-coating speed was 9000r / min, and the spin-coating time was 30s; the spin-coating was carried out at a temperature of 25°C and the air flow rate was 25m / s. The spin-coated electrode was dried under vacuum at a drying temperature of 100°C. After drying for 24 hours, the electrode was covered with an artificial SEI film, and the thickness of the artificial SEI film was about 10 microns.

[0070] Example 4

[0071] A method for preparing an artificial SEI film, the method comprising:

[0072] (1) A 1 M sucrose aqueous solution was placed in a hydrothermal reactor at 220° C. for hydrothermal reaction for 2.5 h. After cooling, the carbon sphere template was obtained by filtration and drying. The drying conditions were: 80° C. for 24 h.

[0073] (2) The carbon sphere template obtained in step (1) is dispersed in a copper acetate solution, and the concentration of copper acetate is 3 mol / L. The carbon sphere template adsorbs copper ions for 24 hours at a temperature of 40° C. After filtration, washing, drying, and muffle furnace calcination, a copper oxide hollow multi-shell layer with 3 shells is obtained.

[0074] (3) The copper oxide hollow multi-shell layer described in step (2) is dispersed in a sodium bisulfite aqueous solution with a concentration of 1M, and the reduction reaction occurs at room temperature for 2 hours. After the reaction is completed, the solid is filtered and washed 3 times, and dried at 70°C for 12 hours to obtain the copper hollow multi-shell layer.

[0075] (4) The copper hollow multi-shell layer is placed in a constant temperature and humidity chamber at 100° C. and a humidity of 60% for 24 hours to obtain a copper-copper oxide composite hollow multi-shell layer.

[0076] (5) The composite hollow multi-shell, polyethylene and pyridine in step (4) are mixed in a mass ratio of 1:0.2:10, and the mixture is ground for 1 hour to obtain a slurry with moderate viscosity. The slurry is evenly applied on the copper foil substrate at an amount of 0.5 mL / cm2. The copper foil coated with the slurry is spin-coated by a coating machine at a spin coating speed of 9000 r / min and a spin coating time of 20 seconds; the spin coating is carried out at a temperature of 40°C and an air flow rate of 10 m / s. After drying at room temperature, the above spin coating process is repeated once. Finally, the spin-coated electrode is dried under vacuum at a drying temperature of 100°C. After drying for 12 hours, an electrode covered with an artificial SEI film is obtained, and the thickness of the artificial SEI film is about 16 microns.

[0077] Example 5

[0078] A method for preparing an artificial SEI film, the method comprising:

[0079] (1) A 1 M sucrose aqueous solution was placed in a hydrothermal reactor at 180° C. for hydrothermal reaction for 2.5 h. After cooling, the carbon sphere template was obtained by filtration and drying. The drying conditions were: 70° C. for 12 h.

[0080] (2) The carbon sphere template obtained in step (1) is dispersed in a cobalt acetate solution with a solution concentration of 1 mol / L. The carbon sphere template adsorbs cobalt ions for 8 hours at a temperature of 30°C, and after filtration, washing, drying, and muffle furnace calcination, a cobalt trioxide hollow multi-shell layer with 4 shells is obtained.

[0081] (3) The cobalt oxide hollow multi-shell layer described in step (2) is reduced by hydrogen at a reduction temperature of 500° C. for a reduction time of 3 h to obtain a cobalt hollow multi-shell layer.

[0082] (4) placing the cobalt hollow multi-shell layer in a constant temperature and humidity chamber at 100° C. and 60% humidity for 24 hours to obtain a cobalt-cobaltous oxide composite hollow multi-shell layer.

[0083] (5) The composite hollow multi-shell, ethyl cellulose and acetone in step (3) were mixed in a mass ratio of 1:0.01:5, and ground for 0.5 h to obtain a slurry with moderate viscosity. The slurry was heated at 0.1 mL / cm 2 The amount of the slurry was evenly applied on the copper foil substrate. The copper foil coated with the slurry was spin-coated using a coating machine, the spin-coating speed was 2000r / min, and the spin-coating time was 20s; the spin-coating was carried out at a temperature of 60°C and the air flow rate was 10m / s. The spin-coated electrode was dried under vacuum at a drying temperature of 90°C for 12 hours to obtain an electrode covered with an artificial SEI film, and the thickness of the artificial SEI film was about 1 micron.

[0084] Example 6

[0085] A method for preparing an artificial SEI film, the method comprising:

[0086] (1) A 1 M sucrose aqueous solution was placed in a hydrothermal reactor at 200° C. for hydrothermal reaction for 2.5 h. After cooling, the carbon sphere template was obtained by filtration and drying. The drying conditions were: 70° C. for 10 h.

[0087] (2) The carbon sphere template obtained in step (1) is dispersed in a copper acetate solution, and the concentration of copper acetate is 0.5 mol / L. The carbon sphere template adsorbs copper ions for 12 hours at a temperature of 60° C. After filtration, washing, drying, and muffle furnace calcination, a copper oxide hollow multi-shell layer is obtained, and the number of shells is 2.

[0088] (3) The copper oxide hollow multi-shell layer described in step (2) is dispersed in a 1M potassium bisulfite aqueous solution, and the reaction occurs at room temperature for 2 hours. After the reaction is completed, the solid is filtered and washed 3 times, and dried at 70° C. for 12 hours to obtain the copper hollow multi-shell layer.

[0089] (4) The copper hollow multi-shell layer is placed in a constant temperature and humidity chamber at 40° C. and a humidity of 20% for 10 hours to obtain a copper-cuprous oxide composite hollow multi-shell layer.

[0090] (5) The copper-based hollow multi-shelled material, ethyl cellulose and ethanol in step (4) are mixed in a mass ratio of 1:0.1:10, and the mixture is ground for 1 hour to obtain a slurry with a moderate viscosity. The slurry is heated at 1 mL / cm 2 The amount of slurry was evenly applied on the copper foil substrate. The copper foil coated with the slurry was spin-coated by a sizing machine, the spin-coating speed was 4000r / min, and the spin-coating time was 60s; the spin-coating was carried out at a temperature of 40°C and the air flow rate was 10m / s. After drying at room temperature, the above spin-coating process was repeated once. The spin-coated electrode was dried under vacuum at a drying temperature of 90°C. After drying for 12 hours, an electrode covered with an artificial SEI film was obtained, and the thickness of the artificial SEI film was about 20 microns.

[0091] Example 7

[0092] A method for preparing an artificial SEI film, the method comprising:

[0093] (1) A 0.2 M sucrose aqueous solution was placed in a hydrothermal reactor at 180° C. for hydrothermal reaction for 2.5 h. After cooling, the carbon sphere template was obtained by filtration and drying. The drying conditions were: 70° C. for 12 h.

[0094] (2) The carbon sphere template obtained in step (1) is dispersed in a copper nitrate solution with a copper nitrate concentration of 2 mol / L. The carbon sphere template adsorbs copper ions for 12 hours at a temperature of 35° C. After filtration, washing, drying, and muffle furnace calcination, a copper oxide hollow multi-shell layer with 3 shells is obtained.

[0095] (3) The copper oxide hollow multi-shell layer described in step (2) is dispersed in a potassium borohydride aqueous solution with a concentration of 1M, and the reduction reaction occurs at room temperature for 2 hours. After the reaction is completed, the solid is filtered and washed 3 times, and dried at 70°C for 12 hours to obtain the copper hollow multi-shell layer.

[0096] (4) The copper hollow multi-shell layer is placed in a constant temperature and humidity chamber at 50° C. and a humidity of 10% for 24 hours to obtain a copper-cuprous oxide composite hollow multi-shell layer.

[0097] (5) The copper-based hollow multi-shell medium, ethyl cellulose and acetone in step (3) are mixed in a mass ratio of 1:0.1:10, and grind for 0.5 hours to obtain a slurry with moderate viscosity. The slurry is evenly applied on the copper foil substrate in an amount of 1 mL / cm2. The copper foil coated with the slurry is spin-coated by a coating machine at a spin coating speed of 9000 r / min and a spin coating time of 10 seconds; the spin coating is carried out at a temperature of 80°C and an air flow rate of 25 m / s. After drying, the above spin coating process is repeated twice. The spin-coated electrode is dried under vacuum at a drying temperature of 90°C. After drying for 20 hours, an electrode covered with an artificial SEI film is obtained, and the thickness of the artificial SEI film is about 30 microns.

[0098] Any contents not described in detail in the present invention can be based on the conventional technical knowledge in the art.

[0099] Finally, it should be noted that the above examples are only used to illustrate the embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the examples, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solution of the present invention does not depart from the spirit and scope of the technical solution of the present invention, and should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a hollow multi-shell artificial solid electrolyte interface (SEI) membrane, comprising the following steps: 1) placing a carbon source aqueous solution into a reaction kettle, heating to obtain micro-nano sized colloidal carbon spheres, and filtering, washing and drying to obtain a carbon sphere template; 2) dispersing the carbon sphere template obtained in step 1) in a metal salt solution, stirring, heat-insulating and adsorbing the obtained suspension, and then filtering, washing, drying and calcining to obtain a metal oxide hollow multi-shell; 3) using a reducing agent to reduce the metal oxide hollow multi-shell layer obtained in step 2) to a metal element hollow multi-shell layer, and then leaving the solid to stand in a constant temperature and humidity environment for a certain period of time to oxidize the solid surface to obtain a metal-metal oxide composite hollow multi-shell layer; 4) The composite hollow multi-shell layer obtained in step 3) is mixed with a binder, and a dispersing solvent is added to grind the mixture into a slurry. The slurry is evenly coated on the surface of the metal foil by spin coating, and then dried to obtain an artificial SEI film.

2. The preparation method according to claim 1, characterized in that The carbon source in step 1) includes one or a combination of two or more of glucose, fructose, sucrose, maltose, starch and citric acid, the concentration of the carbon source aqueous solution is 0.1-5M, and the hydrothermal reaction temperature is 160-220°C.

3. The preparation method according to claim 1 or 2, characterized in that: The metal oxide in step 2) includes one or a combination of two or more of copper oxide, cobalt oxide, nickel oxide, iron oxide, manganese oxide and titanium oxide.

4. The preparation method according to any one of claims 1 to 3, characterized in that The reducing agent in step 3) is sodium borohydride, potassium borohydride, sodium bisulfite, ammonia, hydrogen or carbon monoxide, and the reduction temperature is 25-500°C.

5. The preparation method according to any one of claims 1 to 4, characterized in that: In the step 3), the temperature of the metal single substance hollow multi-shell layer in a constant temperature and humidity environment is 25-100° C., the humidity is 10-60%, and the standing time is 8-24 hours; the metal-metal oxide composite hollow multi-shell layer is one or a combination of two or more of copper-cuprous oxide, copper-copper oxide, cobalt-cobalt oxide, iron-ferroferric oxide, nickel-nickel oxide, manganese-manganese oxide, and titanium-titanium oxide.

6. The preparation method according to any one of claims 1 to 5, characterized in that: In the step 4), the binder includes one or more of polyvinylidene fluoride, polyethylene, polypropylene, and ethyl cellulose; the dispersing solvent includes one or more of ethanol, acetone, terpineol, pyridine, tetrahydrofuran, and ethylene glycol methyl ether; the mass ratio of the hollow multi-shell layer, the binder, and the dispersant is 1:(0.01-1):(1-10), and the grinding time is 0.5-1h.

7. The preparation method according to any one of claims 1 to 6, characterized in that During the spin coating in step 4), the speed of the coating machine is set to 1000-9000 r / min; the spin coating time is 10-60 s; the amount of the spin coating slurry is 0.1-1 mL / cm 2 ; The number of spin coating is 1-3 times; The heating temperature of spin coating is 25-80°C, and the air flow velocity of blowing is 10-25m / s; The metal foil can be copper foil, nickel foil, titanium foil or stainless steel foil.

8. A hollow multi-shell artificial SEI membrane, characterized in that: The hollow multi-shell artificial SEI membrane is obtained by the preparation method described in any one of claims 1-7.

9. The hollow multi-shell artificial SEI membrane according to claim 8, characterized in that The shell wall of the hollow multi-shell layer is 1-4 layers; the thickness of the artificial SEI membrane is 1-30 microns, and the internal composite hollow multi-shell layer is evenly distributed; the artificial SEI membrane is a composite membrane of the hollow multi-shell layer and the binder.

10. Use of the artificial SEI film according to claim 8 or 9 in energy storage batteries.

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