A hollow multi-shell material, its low-temperature preparation method and application

Abstract

This invention relates to the field of functional materials technology, specifically to a hollow multi-shell material and its low-temperature preparation method and application, comprising the following steps: 1) mixing an aqueous or alcoholic solution of precursor A with an oil phase to form a water-in-oil emulsion, or dispersing an aqueous solution of precursor A into droplets via a spray method; 2) freezing the emulsion or droplets obtained in step 1) at a low temperature to obtain ice template particles containing precursor A; 3) adding the ice template particles obtained in step 2) to a precursor B solution, and controlling the temperature program to melt the ice template, causing A and B to undergo precipitation or polymerization reactions to obtain metal fluorides, carbonates, or other hollow multi-shell materials; 4) using the hollow multi-shell material obtained in step 3) as an electrolyte additive. This electrolyte additive can improve the viscosity of the electrolyte, increase ionic conductivity, stabilize the solid electrolyte interface film, effectively inhibit lithium dendrite growth, and improve the coulombic efficiency and cycle life of the battery.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology. Specifically, this invention relates to a hollow multi-shell material, its low-temperature preparation method, and its application. Background Technology

[0002] The structure of a material directly affects its application performance, and this structure-property relationship has important guiding significance in material design, preparation, and performance optimization. Hollow multishelled structures (HoMS) are a novel type of multi-level micro / nanostructured material with excellent specific surface area, hierarchically arranged multilevel shells, and multilevel cavities between the shells. Therefore, hollow multishelled structures possess more modification sites and faster transport channels. The cavities provide a stable material loading space, while the hierarchical shells endow them with unique spatiotemporal order. These characteristics make hollow multishelled structures outstanding in applications such as electrochemical energy storage, microwave absorption, photo / electrocatalysis, and drug loading, and they have gained widespread recognition and favor.

[0003] The energy and environmental crisis is a prominent global challenge. The development and utilization of new energy sources such as solar, wind, and tidal energy are limited by issues such as storage and transmission, hindering their widespread adoption. Energy storage technologies, represented by rechargeable batteries, are key supporting technologies for the large-scale application of new energy sources. Lithium metal batteries, with their highest theoretical energy density (3860 mAh / g) and lowest redox potential (3.04 V vs. SHE), are considered one of the most promising lithium battery anode materials. However, lithium metal batteries face severe challenges, primarily including disordered lithium dendrite growth, volume expansion during cycling, and low battery efficiency at low temperatures. The root causes lie in the uneven mass transfer of electrode materials, slow ion-electron solid-state conduction rates, and decreased fluidity and ionic conductivity of the electrolyte at low temperatures. Numerous studies have shown that specially designed material structures are an effective way to solve these problems. The unique hollow multi-shell structure makes it stand out in lithium battery research, serving as both an active material for positive and negative electrodes and an electrolyte additive.

[0004] The Sequential Templating Approach (STA) can easily and efficiently prepare hollow multi-shell structures of various morphologies and sizes, and has high versatility, making it particularly suitable for structural design in lithium-ion battery applications. However, the STA typically uses carbon-based templates, requiring high-temperature calcination to remove the template, resulting in products primarily consisting of metal oxides. If the target material is not an oxide, further chemical reactions are needed to convert the oxide into the target material, making it difficult to obtain the target material directly in a one-step process. Summary of the Invention

[0005] The purpose of this invention is to provide a hollow multi-shell material, its low-temperature preparation method, and its application. The low-temperature synthesis of HoMS using ice as a template is a novel HoMS preparation method, which fills the gap in the previous sequential template method for synthesizing unstable substances at high temperatures, such as metal fluorides, carbonate ionic compounds, and organic polymers, in a one-step process. The synthesized multi-shell material is then applied as an electrolyte additive to solve the problem of lithium dendrite growth and improve the performance of lithium metal batteries.

[0006] This invention proposes a novel method for synthesizing hollow multi-shell materials, where reactions, nucleation, and crystallization occur at low temperatures to form multi-shells. This avoids the limitations imposed by high-temperature calcination in traditional methods. For example, most organic molecules cannot maintain their properties at high temperatures and can only be synthesized under low-temperature conditions; or high-temperature calcination usually only produces oxides, requiring further reactions to obtain other types of products. Furthermore, addressing the lithium dendrite growth problem in lithium metal batteries, this invention provides a hollow multi-shell material as an electrolyte additive to reduce electrolyte viscosity, improve ionic conductivity, and simultaneously form a lithium fluoride-rich solid electrolyte interphase (SEI) film. This improves the mechanical strength and ion flow uniformity of the SEI film and effectively suppresses the disordered growth of lithium dendrites.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The first aspect of this invention provides a low-temperature preparation method for hollow multi-shell structures. This method includes the following steps:

[0009] 1) Preparation of precursor emulsion: Use an aqueous or alcoholic solution of precursor A as the dispersed phase (aqueous phase) and an organic reagent insoluble in water as the continuous phase. Mix the two phases, add an emulsifier, and then break the dispersed phase droplets by shearing or ultrasonication to obtain a water-in-oil emulsion; or directly disperse the aqueous solution of precursor A into small droplets by spraying.

[0010] 2) Preparation of ice template: Place the water-in-oil emulsion or small droplets obtained in step 1) in a low-temperature environment and freeze for several hours to obtain an ice template containing precursor A;

[0011] 3) Preparation of hollow multi-shell layer: The solution of precursor B is pre-cooled in a low-temperature environment. The ice template obtained in step 2) is mixed into the pre-cooled solution B. The ice template is melted by raising the temperature. At this temperature, precursors A and B undergo precipitation or polymerization reaction to obtain an ionic compound or polymer hollow multi-shell layer.

[0012] The preparation method of this invention, by designing the reaction of precursors A and B, can synthesize hollow multi-shell structures that are insoluble in the solvent of the system. This method has mild synthesis conditions, is simple to operate, and has strong universality, and can synthesize hollow multi-shell materials such as metal fluorides, carbonate plasma compounds, and organic polymers that are previously difficult to prepare and are unstable at high temperatures.

[0013] In addition, the preparation method according to the present invention may also have the following additional technical features:

[0014] According to an embodiment of the present invention, the precursor A in step 1) includes one or a combination of two or more of sodium carbonate, potassium carbonate, sodium sulfate, potassium sulfate, silver nitrate, ferric chloride, sodium fluoride, ammonium fluoride, dopamine, and tannic acid, and the concentration of the precursor A solution is 0.1 to 3 M; the solvent of the precursor A solution is one or a combination of two or more of water, ethanol, methanol, and acetone.

[0015] According to an embodiment of the present invention, the organic oil phase in step 1) includes one or a combination of two or more of n-decane, n-heptane, and cyclohexane.

[0016] According to an embodiment of the present invention, the emulsifier in step 1) includes one or more of the following: sorbitan laurate (span20), sorbitan trioleate (span85), polyoxyethylene sorbitan monooleate (tween80), glyceryl monostearate (Aldo33), polyoxyethylene monolaurate (Atlas G-2129), and polyoxyethylene oleyl ether (Atlas G-3930).

[0017] According to an embodiment of the present invention, the shearing and disruption method in step 1) is performed using a homogenizer with a rotation speed of 2000-10000 r / min and a shearing time of 1-20 min; the ultrasonic disruption is performed using a cell disruptor with an ultrasonic time of 0.5-10 min; the equipment used for spraying to prepare small droplets includes a sprayer, a humidifier, a small spray bottle, etc.

[0018] According to an embodiment of the present invention, in step 2), the temperature of the low-temperature chamber is -196℃ to 0℃, and the freezing time is 0.1-24 h;

[0019] According to an embodiment of the present invention, in step 3), precursor B includes one or more of the following: calcium chloride, calcium acetate, barium chloride, sodium chloride, ammonia, lithium nitrate, lithium chloride, lithium acetate, tris(hydroxymethyl)aminomethane, hydrogen peroxide, and ferric chloride. The solvent of the precursor B solution includes one or more of the following: methanol, ethanol, isopropanol, and acetone. The concentration of the precursor B solution is 0.1–3 M. The pre-cooling temperature is -40°C to -10°C, and the pre-cooling time is 5 min to 1 h.

[0020] According to an embodiment of the present invention, the reaction temperature in step 3) is -40℃ to 20℃, and the reaction time is 1 to 24 hours;

[0021] A second aspect of the present invention provides a variety of hollow multi-shell structural materials.

[0022] According to an embodiment of the present invention, in step 3), the hollow multi-shell of the ionic compound or polymer is one or more of calcium carbonate, barium sulfate, barium carbonate, silver chloride, iron hydroxide, lithium fluoride, polydopamine, and iron-tannic acid; the number of shells in the hollow multi-shell is 1-5; the diameter is 0.2-3 micrometers and the shell wall thickness is 20-200 nanometers.

[0023] A third aspect of the present invention provides the application of hollow multi-shell structures as described in the second aspect in the field of lithium batteries.

[0024] According to embodiments of the present invention, a hollow multi-shell structure is provided as an electrolyte additive. The hollow multi-shell structure material is added to the electrolyte, dispersed evenly, and then a battery is assembled using the modified electrolyte for battery performance testing. The hollow multi-shell electrolyte additive is used to modify the electrolyte properties of the battery, reducing electrolyte viscosity, increasing ionic conductivity, increasing the lithium fluoride content in the SEI, and reducing local current density, thereby significantly improving the battery's coulombic efficiency, cycle life, and safety.

[0025] In addition, the preparation method according to the present invention may also have the following additional technical features:

[0026] According to an embodiment of the present invention, the proportion of the multi-shell electrolyte additive added in step 4) is 0% to 20%.

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

[0028] 1) The ice-template low-temperature synthesis method described in this invention is a novel approach for preparing hollow multi-shell layers. By considering the solubility of precursors and products in solvents, suitable precipitation or polymerization reactions are designed to obtain hollow multi-shell layers. This method is carried out at low temperatures, avoiding the limitations imposed by high-temperature calcination on the synthesized products. It allows for the design and synthesis of novel ionic compounds or organic polymer multi-shell layers, substances that cannot be obtained in a single step using traditional high-temperature calcination. For specific applications, it enables in-situ loading of drugs or active materials within the multi-shell framework. For example, drug molecules or electrode active materials such as sulfur and phosphorus are pre-dispersed in an ice template; after reaction, the drug molecules or electrode active materials are directly loaded in-situ into the synthesized hollow multi-shell layer, significantly improving the loading rate.

[0029] 2) The prepared hollow multi-shell lithium fluoride electrolyte was used as an electrolyte additive for electrolyte modification. Adding 5% (wt%) of the hollow multi-shell lithium fluoride electrolyte additive reduced the electrolyte viscosity by 12.6%. Ionic conductivity is inversely proportional to electrolyte viscosity, thus improving conductivity. After cycling, the lithium fluoride content in the SEI on the electrode surface increased from 0% to 5.82%, and the internal content increased from 1.10% to 14.11%. Lithium fluoride in the SEI has a suitable band gap and diffusion barrier, high shear modulus, bulk modulus, and the highest voltage stability window. Therefore, increasing the lithium fluoride content in the SEI can effectively improve SEI quality and significantly reduce lithium dendrite growth.

[0030] 3) The electrolyte modified with hollow multi-shell lithium fluoride additives was used in long-cycle battery testing, using an ether-based electrolyte at 1 mA / cm². 2 After 300 cycles at the current density, the coulombic efficiency remains above 99.5%; when using a carbonate electrolyte, at 1 mA / cm²... 2 When cycled 140 times at the current density, the coulombic efficiency is over 96%, which far exceeds the performance of lithium metal batteries based on the same composition of nanoparticles or electrolytes without any additives. Attached Figure Description

[0031] Figure 1 This is a transmission electron microscope image of a hollow multi-shell lithium fluoride structure from Embodiment 1 of the present invention;

[0032] Figure 2 This is the X-ray diffraction pattern of the hollow multi-shell lithium fluoride structure in Embodiment 1 of the present invention;

[0033] Figure 3 This is the XPS full spectrum of the SEI of the battery electrode without lithium fluoride in Example 1 of this invention;

[0034] Figure 4 This is the F 1s spectrum of the SEI of the battery electrode without lithium fluoride in Example 1 of the present invention;

[0035] Figure 5 This is the XPS full spectrum of the SEI of the battery electrode with 5% lithium fluoride hollow multi-shell added in Example 1 of this invention;

[0036] Figure 6 This is the F 1s spectrum of the SEI of the battery electrode with 5% lithium fluoride hollow multi-shell added in Example 1 of the present invention;

[0037] Figure 7 This refers to the proportion of lithium fluoride in the full spectrum of the SEI in Example 1 of this invention;

[0038] Figure 8 This is a coulombic efficiency diagram of the battery in Embodiment 1 of the present invention during battery cycling;

[0039] Figure 9 This is a transmission electron microscope image of the hollow multi-shell calcium carbonate structure in Example 4 of this invention. Detailed Implementation

[0040] The present invention will be further described below with reference to specific embodiments.

[0041] This invention provides a method for the low-temperature preparation of hollow multi-shell ice templates and their application in batteries. The method and application include:

[0042] (a) A 0.1-3 M salt solution is used as the dispersed phase, and an organic reagent insoluble in water is used as the continuous phase. The two phases are mixed, and an emulsifier is added. The aqueous phase droplets are then broken up by shearing or ultrasonication to obtain a water-in-oil emulsion; or the aqueous solution of precursor A is directly dispersed into small droplets by spraying.

[0043] The salt solution is an aqueous solution of one or more of the following: sodium carbonate, potassium carbonate, sodium sulfate, potassium sulfate, silver nitrate, ferric chloride, sodium fluoride, ammonium fluoride, dopamine, and tannic acid. Solution A has a concentration of 0.1–3 M. The oil phase reagent is one or more of the following: n-decane, n-heptane, and cyclohexane. The emulsifier is one or more of the following: Span20, Span85, Tween80, Aldo33, Atlas G-2129, and Atlas G-3930. Homogenization is performed using a homogenizer at a speed of 2000–10000 r / min for 1–20 min, or ultrasonication is performed using a cell disruptor for 0.5–10 min. Equipment used for preparing small droplets by spraying includes sprayers, humidifiers, and small spray bottles.

[0044] (b) The water-in-oil emulsion or droplets obtained in step a) are placed in a low-temperature environment and frozen for 0.1–24 h to obtain an ice template containing precursor A. The freezing temperature is -196°C to 0°C.

[0045] (c) Pre-cool the solution of precursor B in a low-temperature environment. Mix the ice template obtained in step b) into the pre-cooled solution B, and control the melting of the ice template by raising the temperature. At this temperature, precursors A and B undergo precipitation or polymerization reactions to obtain ionic compounds or hollow multi-shell polymers.

[0046] The precooling temperature is -40℃ to -10℃, and the precooling time is 5 min to 1 h. Precursor B includes one or more of the following: calcium chloride, calcium acetate, barium chloride, sodium chloride, ammonia, lithium nitrate, lithium chloride, lithium acetate, tris(hydroxymethyl)aminomethane, hydrogen peroxide, and ferric chloride. The solvent for the precursor B solution includes one or more of the following: methanol, ethanol, isopropanol, and acetone. The reaction temperature is -40℃ to 20℃, and the reaction time is 1 to 24 h; the concentration of the precursor B solution is 0.1 to 3 M.

[0047] (d) Add the hollow multi-shell layer obtained in step c) to the electrolyte, disperse it evenly, and then assemble the battery with the modified electrolyte for long-cycle testing.

[0048] The hollow multi-shell layer is composed of one or more of the following: calcium carbonate, barium sulfate, barium carbonate, silver chloride, ferric hydroxide, lithium fluoride, polydopamine, and iron-tannic acid. The hollow multi-shell layer is added to the electrolyte at a ratio of 0% to 20%.

[0049] Example 1

[0050] A method for low-temperature preparation of a hollow multi-shell ice template and its application in batteries, including:

[0051] (1) A 0.5M sodium fluoride aqueous solution was used as the aqueous phase, and cyclohexane was used as the oil phase. The two phases were mixed, and Aldo33 emulsifier was added. The aqueous phase droplets were then sheared and broken up by a homogenizer to obtain a water-in-oil emulsion. The homogenizer speed was 4000 r / min and the time was 20 min.

[0052] (2) The water-in-oil emulsion obtained in step 1) was placed in a -40℃ low temperature box and frozen for 2 h to obtain an ice template containing sodium fluoride;

[0053] (3) The isopropanol solution of lithium chloride was pre-cooled in a low temperature box at -40℃ for 30 min. The ice template obtained in step 2) was mixed into the pre-cooled lithium chloride solution and melted at -20℃. At this temperature, sodium fluoride and lithium chloride precipitated and the reaction time was 6 h to obtain a hollow multi-shell lithium fluoride.

[0054] (4) The lithium fluoride hollow multi-shell obtained in step 3) was added to the electrolyte at a ratio of 0% and 5% (wt%) (the electrolyte solute was 1M lithium bis(trifluoromethanesulfonyl)imide, and the solvent was dioxolane:ethylene glycol dimethyl ether = 1:1). The mixture was stirred at 200 r / min for 18 h to ensure uniform dispersion, and then assembled into a coin cell using the modified electrolyte. The cell was tested at a current of 1 mA / cm². 2 The charge / discharge capacity is 1 mA / cm. 2 Battery long-cycle testing was conducted under these conditions.

[0055] (5) In step 4), the battery is connected to a current of 1 mA / cm. 2 The lithium deposition capacity is 1 mAh / cm³. 2 Under certain conditions, lithium was intercalated into the negative electrode, and X-ray photoelectron spectroscopy was performed on the surface of the negative electrode obtained after the battery was disassembled.

[0056] The obtained transmission electron microscope images of hollow multi-shell lithium fluoride are as follows: Figure 1 As shown, it is a hollow sphere with two shells, a diameter of 500 nm, and a shell wall thickness of 50 nm. The X-ray diffraction pattern of the hollow multi-shell lithium fluoride is shown below. Figure 2 As shown, the material peak signal is consistent with the lithium fluoride standard card #04-0857. Figure 3 and Figure 5 The images show the X-ray photoelectron spectra of the SEI electrodes after cycling, with and without lithium fluoride and with 5% lithium fluoride. The signal around 684 eV corresponds to fluorine, and the fluorine signal is significantly stronger after adding lithium fluoride than when it is not added. Figure 4 and Figure 6 The X-ray photoelectron diffraction fine spectra of fluorine in the SEI electrodes after cycling with and without lithium fluoride and with 5% lithium fluoride hollow multishells are shown respectively. The lithium fluoride signal peak is around 684.5 eV. The amount of lithium fluoride in the SEI is significantly increased after the addition of lithium fluoride hollow multishells. Figure 7 This represents the proportion of lithium fluoride in the SEI. The battery cycle efficiency is as follows: Figure 8 As shown, at 1 mA / cm 2 When the current was cycled for 300 cycles, the coulombic efficiency of the battery with lithium fluoride hollow multi-shell was still maintained at 99.5%. Obviously, its cycle life and coulombic efficiency are better than those of the battery without lithium fluoride additive.

[0057] Example 2

[0058] A method for low-temperature preparation of a hollow multi-shell ice template and its application in batteries, including:

[0059] (1) A 0.1M ammonium fluoride aqueous solution was used as the aqueous phase, and cyclohexane was used as the oil phase. The two phases were mixed, and Tween80 emulsifier was added. The aqueous phase droplets were then sheared and broken up by a homogenizer to obtain a water-in-oil emulsion. The homogenizer speed was 5000 r / min and the time was 8 min.

[0060] (2) The water-in-oil emulsion obtained in step 1) was placed in a -30℃ low temperature box and frozen for 0.5h to obtain an ice template containing ammonium fluoride;

[0061] (3) Pre-cool the lithium nitrate solution in acetone at -30°C for 30 min. Mix the ice template obtained in step 2) into the pre-cooled lithium nitrate solution and melt the ice template at 5°C. At this temperature, ammonium fluoride and lithium nitrate precipitate. The reaction time is 24 h to obtain a hollow multi-shell lithium fluoride with 1 shell, a diameter of 0.2 micrometers, and a shell wall thickness of 20 nanometers.

[0062] (4) The lithium fluoride hollow multi-shell obtained in step 3) was added to the electrolyte at a ratio of 0% and 15% (wt%) (the electrolyte solute was 1M lithium bis(trifluoromethanesulfonyl)imide, and the solvent was dioxolane:ethylene glycol dimethyl ether = 1:1). The mixture was stirred at 800 r / min for 2 h, and then assembled into a coin cell using the modified electrolyte. The battery was subjected to long-cycle testing under the conditions of a current of 1 mA and a charge / discharge capacity of 1 mH.

[0063] (5) In step 4), the battery is connected to a current of 1 mA / cm. 2 The lithium deposition capacity is 1 mA / cm². 2 Under certain conditions, lithium was intercalated into the negative electrode, and X-ray photoelectron spectroscopy was performed on the surface of the negative electrode obtained after the battery was disassembled.

[0064] Example 3

[0065] A method for low-temperature preparation of a hollow multi-shell ice template and its application in batteries, including:

[0066] (1) An aqueous solution of 0.8 M ammonium fluoride was used as the aqueous phase and cyclohexane as the oil phase. The two phases were mixed, and Atlas G-3930 emulsifier was added. The aqueous phase droplets were then ultrasonically disrupted using a cell disruptor at a power of 180 W for 2 min.

[0067] (2) The water-in-oil emulsion obtained in step 1) was placed in a -25°C low temperature box and frozen for 1 hour to obtain an ice template containing ammonium fluoride;

[0068] (3) Pre-cool the lithium acetate acetone solution in a -30℃ low-temperature box for 30 min. Mix the ice template obtained in step 2) into the pre-cooled lithium nitrate solution and melt the ice template at 15℃. At this temperature, ammonium fluoride and lithium acetate precipitate. The reaction time is 4 h to obtain a hollow multi-shell lithium fluoride with 3 shells, a diameter of 1 micrometer, and a shell wall thickness of 100 nanometers.

[0069] (4) The lithium fluoride hollow multi-shell obtained in step 3) was added to the electrolyte at a ratio of 0% and 10% (wt%) (the electrolyte solute was 1M lithium bis(trifluoromethanesulfonyl)imide, and the solvent was dioxolane:ethylene glycol dimethyl ether = 1:1). The mixture was stirred at 800 r / min for 2 h, and then assembled into a coin cell using the modified electrolyte. The cell was tested at a current of 1 mA / cm². 2 The charge / discharge capacity is 1 mAh / cm³. 2 Battery long-cycle testing was conducted under these conditions.

[0070] (5) In step 4), the battery is connected to a current of 1 mA / cm. 2 The lithium deposition capacity is 1 mAh / cm³. 2 Under certain conditions, lithium was intercalated into the negative electrode, and X-ray photoelectron spectroscopy was performed on the surface of the negative electrode obtained after the battery was disassembled.

[0071] Example 4

[0072] A method for low-temperature preparation of a hollow multi-shell ice template and its application in batteries, including:

[0073] (1) A 3M sodium carbonate aqueous solution was used as the aqueous phase, and n-heptane was used as the oil phase. The two phases were mixed, and then Span85 and Tween80 were added as emulsifiers. The aqueous phase droplets were then ultrasonically disrupted using a cell disruptor with an ultrasonic power of 100 W for 0.5 min.

[0074] (2) The water-in-oil emulsion obtained in step 1) was placed in a 0°C low-temperature chamber and frozen for 24 h to obtain an ice template containing sodium carbonate;

[0075] (3) Pre-cool the calcium chloride ethanol solution in a -10℃ low-temperature box for 5 min. Mix the ice template obtained in step 2) into the pre-cooled calcium chloride solution and melt the ice template at 0℃. At this temperature, sodium carbonate and calcium chloride precipitate. The reaction time is 1 h to obtain a hollow multi-shell calcium carbonate with 5 shells, a diameter of 3 micrometers, and a shell wall thickness of 200 nanometers.

[0076] (4) The calcium carbonate hollow multi-shell obtained in step 3) was added to the electrolyte at a ratio of 0% and 3% (wt%) (the electrolyte solute was 1M lithium bis(trifluoromethanesulfonyl)imide, and the solvent was dioxolane:ethylene glycol dimethyl ether = 1:1). The mixture was stirred at 600 r / min for 5 h, and then assembled into a coin cell using the modified electrolyte. The cell was tested at a current of 1 mA / cm². 2 The charge / discharge capacity is 1 mA / cm². 2 Battery long-cycle testing was conducted under these conditions.

[0077] (5) In step 4), the battery is connected to a current of 1 mA / cm. 2 The lithium deposition capacity is 1 mAh / cm³. 2 Under certain conditions, lithium was intercalated into the negative electrode, and X-ray photoelectron spectroscopy was performed on the surface of the negative electrode obtained after the battery was disassembled.

[0078] Transmission electron microscopy images of the obtained hollow multi-shell calcium carbonate are as follows: Figure 9 As shown.

[0079] Example 5

[0080] A method for low-temperature preparation of a hollow multi-shell ice template and its application in batteries, including:

[0081] (1) A 3 M sodium carbonate water and ethanol mixed solution was used as the dispersed phase, and cyclohexane was used as the oil phase. The water and oil phases were mixed, and then Span 85 and Atlas G-3930 were added as emulsifiers. The aqueous phase droplets were then ultrasonically broken up using a cell disruptor with an ultrasonic power of 100 W for 1 min.

[0082] (2) The water-in-oil emulsion obtained in step 1) was placed in a -18℃ low temperature box and frozen for 1 h to obtain an ice template containing sodium chloride;

[0083] (3) Pre-cool the barium chloride ethanol solution in a -10℃ low-temperature box for 5 min. Mix the ice template obtained in step 2) into the pre-cooled barium chloride solution and melt the ice template at 0℃. At this temperature, sodium carbonate and barium chloride precipitate. The reaction time is 1 h to obtain barium carbonate hollow multi-shell with 3 shells; the diameter is 2 micrometers and the shell wall thickness is 150 nanometers.

[0084] (4) The barium chloride hollow multi-shell obtained in step 3) was added to the electrolyte at a ratio of 0% and 20% (wt%) (the electrolyte solute was 1M lithium bis(trifluoromethanesulfonyl)imide, and the solvent was dioxolane:ethylene glycol dimethyl ether = 1:1). The mixture was stirred at 200 r / min for 7 h, and then assembled into a coin cell using the modified electrolyte. The cell was tested at a current of 1 mA / cm². 2 The charge / discharge capacity is 1 mAh / cm³. 2 Battery long-cycle testing was conducted under these conditions.

[0085] (5) In step 4), the battery is connected to a current of 1 mA / cm. 2 The lithium deposition capacity is 1 mAh / cm³. 2 Under certain conditions, lithium was intercalated into the negative electrode, and X-ray photoelectron spectroscopy was performed on the surface of the negative electrode obtained after the battery was disassembled.

[0086] Example 6

[0087] A method for low-temperature preparation of a hollow multi-shell ice template and its application in batteries, including:

[0088] (1) A 0.5M mixed solution of tannic acid and ammonia was used as the dispersed phase, and n-heptane was used as the oil phase. The water and oil phases were mixed, and Span 85 was added as an emulsifier. The aqueous phase droplets were then ultrasonically disrupted using a cell disruptor with an ultrasonic power of 100 W for 1 min.

[0089] (2) The water-in-oil emulsion obtained in step 1) was placed in a -28℃ low temperature box and frozen for 8 h to obtain an ice template containing tannic acid;

[0090] (3) Pre-cool the ethanol solution of ferric chloride in a -40°C low-temperature box for 5 min. Mix the ice template obtained in step 2) into the pre-cooled ferric chloride solution and melt the ice template at 15°C. At this temperature, tannic acid and ferric chloride react for 5 h to obtain an iron-tannic acid hollow multi-shell structure with 2 shells, a diameter of 1 micrometer, and a shell wall thickness of 50 nanometers.

[0091] (4) The iron-tannic acid hollow multi-shell obtained in step 3) was added to the electrolyte at a ratio of 0% and 5% (wt%) (the electrolyte solute was 1M lithium bis(trifluoromethanesulfonyl)imide, and the solvent was dioxolane:ethylene glycol dimethyl ether = 1:1). The mixture was stirred at 400 r / min for 4 h, and then assembled into a coin cell using the modified electrolyte. The cell was tested at a current of 1 mA / cm². 2 The charge / discharge capacity is 1 mAh / cm³. 2 Battery long-cycle testing was conducted under these conditions.

[0092] (5) In step 4), the battery is connected to a current of 1 mA / cm. 2 The lithium deposition capacity is 1 mAh / cm³. 2 Under certain conditions, lithium was intercalated into the negative electrode, and X-ray photoelectron spectroscopy was performed on the surface of the negative electrode obtained after the battery was disassembled.

[0093] Example 7

[0094] A method for low-temperature preparation of a hollow multi-shell ice template and its application in batteries, including:

[0095] (1) A 0.5M sodium chloride aqueous solution was used as the dispersed phase, and n-decane was used as the oil phase. The water and oil phases were mixed, and Tween 80 was added as an emulsifier. The aqueous phase droplets were then sheared and broken up by a homogenizer to obtain a water-in-oil emulsion. The homogenizer speed was 2000 r / min and the time was 6 min.

[0096] (2) Place the water-in-oil emulsion obtained in step 1) in a -25°C low temperature box and freeze for 1 h to obtain an ice template containing ferric chloride;

[0097] (3) Pre-cool the ethanol solution of silver nitrate in a low-temperature chamber at -40℃ for 5 min. Mix the ice template obtained in step 2) into the pre-cooled silver nitrate solution and melt the ice template at 0℃. At this temperature, silver nitrate and ferric chloride react for 1 h to obtain a hollow multi-shell silver chloride with 2 shells, a diameter of 1 micrometer, and a shell wall thickness of 30 nanometers.

[0098] (4) The silver chloride hollow multi-shell obtained in step 3) was added to the electrolyte at a ratio of 0% and 2% (wt%) (the electrolyte solute was 1M lithium bis(trifluoromethanesulfonyl)imide, and the solvent was dioxolane:ethylene glycol dimethyl ether = 1:1). The mixture was stirred at 800 r / min for 8 h, and then assembled into a coin cell using the modified electrolyte. The cell was tested at a current of 1 mA / cm². 2 The charge / discharge capacity is 1 mAh / cm³. 2 Battery long-cycle testing was conducted under these conditions.

[0099] (5) In step 4), the battery is connected to a current of 1 mA / cm. 2 The lithium deposition capacity is 1 mAh / cm³. 2 Under certain conditions, lithium was intercalated into the negative electrode, and X-ray photoelectron spectroscopy was performed on the surface of the negative electrode obtained after the battery was disassembled.

[0100] Example 8

[0101] A method for low-temperature preparation of a hollow multi-shell ice template and its application in batteries, including:

[0102] (1) A 2M ferric chloride aqueous solution was used as the aqueous phase and cyclohexane was used as the oil phase. The two phases were mixed and Aldo33 emulsifier was added. The aqueous phase droplets were then ultrasonically broken using a cell disruptor with an ultrasonic power of 150 W for 8 minutes.

[0103] (2) The water-in-oil emulsion obtained in step 1) was placed in a -30℃ low temperature box and frozen for 8 h to obtain an ice template containing ferric chloride;

[0104] (3) Pre-cool the mixed solution of ammonia and acetone in a low-temperature chamber at -10℃ for 30 min. Mix the ice template obtained in step 2) into the pre-cooled mixed solution of ammonia and acetone, melt the ice template at 5℃, at which temperature ferric chloride and ammonia precipitate, and the reaction time is 1 h to obtain hollow multi-shell ferric hydroxide with 3 shells; the diameter is 3 micrometers and the shell wall thickness is 100 nanometers.

[0105] (4) The hollow multi-shell iron hydroxide obtained in step 3) was added to the electrolyte at a ratio of 0% and 3% (wt%) (the electrolyte solute was 1M lithium bis(trifluoromethanesulfonyl)imide, and the solvent was dioxolane:ethylene glycol dimethyl ether = 1:1). The mixture was stirred at 800 r / min for 2 h, and then assembled into a coin cell using the modified electrolyte. The cell was tested at a current of 1 mA / cm². 2 The charge / discharge capacity is 1 mAh / cm³. 2 Battery long-cycle testing was conducted under these conditions.

[0106] (5) The battery in step 4) was subjected to lithium intercalation at the negative electrode under the conditions of a current of 1 mA / cm2 and a lithium deposition capacity of 1 mAh / cm2, and the surface of the negative electrode obtained after the battery was disassembled was subjected to X-ray photoelectron spectroscopy test.

[0107] Example 9

[0108] A method for low-temperature preparation of a hollow multi-shell ice template and its application in batteries, including:

[0109] (1) A 0.1M potassium carbonate aqueous solution was used as the aqueous phase, and n-decane was used as the oil phase. The two phases were mixed, and Atlas G-2129 was added as an emulsifier. The aqueous phase droplets were then ultrasonically disrupted using a cell disruptor with an ultrasonic power of 200W for 7 minutes.

[0110] (2) The water-in-oil emulsion obtained in step 1) was placed in a -15℃ low temperature box and frozen for 8 h to obtain an ice template containing potassium carbonate;

[0111] (3) Pre-cool the ethanol solution of calcium acetate and calcium chloride in a low-temperature box at -15°C for 1 h. Mix the ice template obtained in step 2) into the pre-cooled calcium acetate and calcium chloride solution, melt the ice template at 0°C, and precipitation occurs at this temperature. The reaction time is 16 h to obtain hollow multi-shell calcium carbonate with 2 shells; the diameter is 0.8 micrometers and the shell wall thickness is 40 nanometers.

[0112] (4) The calcium carbonate hollow multi-shell obtained in step 3) was added to the electrolyte at a ratio of 0% and 8% (wt%) (the electrolyte solute was 1M lithium bis(trifluoromethanesulfonyl)imide, and the solvent was dioxolane:ethylene glycol dimethyl ether = 1:1). The mixture was stirred at 500 r / min for 7 h, and then assembled into a coin cell using the modified electrolyte. The cell was tested at a current of 1 mA / cm². 2 The charge / discharge capacity is 1 mAh / cm³. 2 Battery long-cycle testing was conducted under these conditions.

[0113] (5) In step 4), the battery is connected to a current of 1 mA / cm.2 The lithium deposition capacity is 1 mAh / cm³. 2 Under certain conditions, lithium was intercalated into the negative electrode, and X-ray photoelectron spectroscopy was performed on the surface of the negative electrode obtained after the battery was disassembled.

[0114] Example 10

[0115] A method for low-temperature preparation of a hollow multi-shell ice template and its application in batteries, including:

[0116] (1) A 2M sodium sulfate aqueous solution was sprayed through a humidifier to obtain small droplets;

[0117] (2) Disperse the small droplets obtained in step 1) in liquid nitrogen (temperature about -196℃) and freeze for 0.1 h to obtain an ice template containing sodium sulfate;

[0118] (3) Pre-cool the barium chloride ethanol solution in a low-temperature chamber at -15℃ for 1 h. Mix the ice template obtained in step 2) into the pre-cooled barium chloride solution and melt the ice template at -20℃. At this temperature, barium chloride and sodium sulfate precipitate. The reaction time is 5 h to obtain a hollow multi-shell barium sulfate with 2 shells, a diameter of 1.2 micrometers, and a shell wall thickness of 60 nanometers.

[0119] (4) The barium sulfate hollow multi-shell obtained in step 3) was added to the electrolyte at a ratio of 0% and 5% (wt%) (the electrolyte solute was 1 M lithium bis(trifluoromethanesulfonyl)imide, and the solvent was dioxolane:ethylene glycol dimethyl ether = 1:1). The mixture was stirred at 300 r / min for 24 h, and then assembled into a coin cell using the modified electrolyte. The cell was tested at a current of 1 mA / cm². 2 The charge / discharge capacity is 1 mAh / cm³. 2 Battery long-cycle testing was conducted under these conditions.

[0120] (5) In step 4), the battery is connected to a current of 1 mA / cm. 2 The lithium deposition capacity is 1 mAh / cm³. 2 Under certain conditions, lithium was intercalated into the negative electrode, and X-ray photoelectron spectroscopy was performed on the surface of the negative electrode obtained after the battery was disassembled.

[0121] Example 11

[0122] A method for low-temperature preparation of a hollow multi-shell ice template and its application in batteries, including:

[0123] (1) A 1M potassium sulfate aqueous solution was used as the aqueous phase, and n-decane was used as the oil phase. The two phases were mixed, and Span 20 was added as an emulsifier. The aqueous phase droplets were then sheared and broken up by a homogenizer to obtain a water-in-oil emulsion. The homogenizer speed was 10000 r / min and the time was 20 min.

[0124] (2) The water-in-oil emulsion obtained in step 1) was placed in a -10℃ low temperature box and frozen for 13 h to obtain an ice template containing sodium sulfate;

[0125] (3) Pre-cool the ethanol solution of barium chloride in a low-temperature chamber at -15°C for 1 h. Mix the ice template obtained in step 2) into the pre-cooled barium chloride solution and melt the ice template at -20°C. At this temperature, barium chloride and potassium sulfate precipitate. The reaction time is 5 h to obtain a hollow multi-shell barium sulfate with 2 shells, a diameter of 1 micrometer, and a shell wall thickness of 50 nanometers.

[0126] (4) The barium sulfate hollow multi-shell obtained in step 3) was added to the electrolyte at a ratio of 0% and 9% (wt%) (the electrolyte solute was 1M lithium bis(trifluoromethanesulfonyl)imide, and the solvent was dioxolane:ethylene glycol dimethyl ether = 1:1). The mixture was stirred at 300 r / min for 24 h, and then assembled into a coin cell using the modified electrolyte. The cell was tested at a current of 1 mA / cm². 2 The charge / discharge capacity is 1 mAh / cm³. 2 Battery long-cycle testing was conducted under these conditions.

[0127] (5) In step 4), the battery is connected to a current of 1 mA / cm. 2 The lithium deposition capacity is 1 mAh / cm³. 2 Under certain conditions, lithium was intercalated into the negative electrode, and X-ray photoelectron spectroscopy was performed on the surface of the negative electrode obtained after the battery was disassembled.

[0128] Example 12

[0129] A method for low-temperature preparation of a hollow multi-shell ice template and its application in batteries, including:

[0130] (1) A 0.5M dopamine monomer aqueous solution was used as the aqueous phase, and n-heptane was used as the oil phase. The two phases were mixed, and Span20 was added as an emulsifier. The aqueous phase droplets were then sheared and broken up by a homogenizer to obtain a water-in-oil emulsion. The homogenizer speed was 2000 r / min and the time was 2 min.

[0131] (2) The water-in-oil emulsion obtained in step 1) was placed in a -30℃ low temperature box and frozen for 8 h to obtain an ice template containing dopamine monomer;

[0132] (3) The ethanol solution of tris(hydroxymethyl)aminomethane was pre-cooled in a low-temperature chamber at -7°C for 3 h. The ice template obtained in step 2) was mixed into the pre-cooled tris(hydroxymethyl)aminomethane solution and the ice template was melted at -7°C. The polymerization reaction occurred at this temperature for 12 h to obtain polydopamine hollow multi-shell layer with 2 shells, a diameter of 1 micrometer, and a shell wall thickness of 40 nanometers.

[0133] (4) The polydopamine hollow multishell obtained in step 3) was added to the electrolyte at a ratio of 0% and 4% (wt%) (the electrolyte solute was 1M lithium bis(trifluoromethanesulfonyl)imide, and the solvent was dioxolane:ethylene glycol dimethyl ether = 1:1). The mixture was stirred at 300 r / min for 24 h, and then assembled into a coin cell using the modified electrolyte. The cell was tested at a current of 1 mA / cm². 2 The charge / discharge capacity is 1 mAh / cm³. 2 Battery long-cycle testing was conducted under these conditions.

[0134] (5) In step 4), the battery is connected to a current of 1 mA / cm. 2 The lithium deposition capacity is 1 mAh / cm³. 2 Under certain conditions, lithium was intercalated into the negative electrode, and X-ray photoelectron spectroscopy was performed on the surface of the negative electrode obtained after the battery was disassembled.

[0135] Example 13

[0136] A method for low-temperature preparation of a hollow multi-shell ice template and its application in batteries, including:

[0137] (1) A 3 M concentration of dopamine aqueous solution was treated with a sprayer to obtain small droplets;

[0138] (2) Disperse the small droplets obtained in step 1) in a -25℃ low temperature chamber and freeze for 24 h to obtain an ice template containing dopamine;

[0139] (3) Pre-cool the hydrogen peroxide-ethanol solution in a -25°C low-temperature chamber for 10 min. Mix the ice template obtained in step 2) into the pre-cooled hydrogen peroxide-ethanol solution, melt the ice template at 20°C, and a polymerization reaction occurs at this temperature for 24 h to obtain a polydopamine hollow multi-shell structure with 4 shells, a diameter of 2 micrometers, and a shell wall thickness of 120 nanometers.

[0140] (4) The polydopamine hollow multishell obtained in step 3) was added to the electrolyte at a ratio of 0% and 20% (wt%) (the electrolyte solute was 1M lithium bis(trifluoromethanesulfonyl)imide, and the solvent was dioxolane:ethylene glycol dimethyl ether = 1:1). The mixture was stirred at 700 r / min for 3 h, and then assembled into a coin cell using the modified electrolyte. The cell was tested at a current of 1 mA / cm². 2 The charge / discharge capacity is 1 mAh / cm³. 2 Battery long-cycle testing was conducted under these conditions.

[0141] (5) In step 4), the battery is connected to a current of 1 mA / cm. 2 The lithium deposition capacity is 1 mAh / cm³. 2 Under certain conditions, lithium was intercalated into the negative electrode, and X-ray photoelectron spectroscopy was performed on the surface of the negative electrode obtained after the battery was disassembled.

[0142] All aspects not described in detail in this invention can be covered using conventional technical knowledge in the field.

[0143] Finally, it should be noted that the above embodiments are only used to illustrate the implementation of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention will not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A low-temperature preparation method for a hollow multi-shell material, characterized in that, Includes the following steps: 1) Using the precursor A solution as the dispersed aqueous phase and the water-insoluble organic reagent as the continuous oil phase, the two phases are mixed, an emulsifier is added, and the mixture is subjected to shearing or ultrasonic crushing to obtain a water-in-oil emulsion; or the aqueous solution of precursor A is directly dispersed into small droplets by spraying. 2) Place the water-in-oil emulsion or small droplets obtained in step 1) in a low-temperature environment and freeze for several hours to obtain ice template particles containing precursor A; the freezing temperature in step 2) is -196℃ to 0℃, and the freezing time is 0.1-24h. 3) The solution of precursor B is pre-cooled in a low-temperature environment. The ice template particles obtained in step 2) are added to the pre-cooled solution B. The temperature is raised by program control to melt the ice template. During this process, precursors A and B undergo precipitation or polymerization reaction. After a certain reaction time, a hollow multi-shell structure material is obtained. The pre-cooling temperature in step 3) is -40℃ to -10℃.

2. The preparation method according to claim 1, characterized in that, The precursor A in step 1) includes one or more of the following: sodium carbonate, potassium carbonate, sodium sulfate, potassium sulfate, silver nitrate, ferric chloride, sodium fluoride, ammonium fluoride, dopamine, and tannic acid. The solvent of the precursor A solution is one or a combination of two or more of water, ethanol, methanol, and acetone. The concentration of the precursor A solution is 0.1–3 M; The oil phase includes one or more of n-decane, n-heptane, and cyclohexane; The emulsifier includes one or more of the following: Sorbitol Laurate (span20), Sorbitol Trioleate (span85), Polyoxyethylene Sorbitol Monooleate (tween80), Glyceryl Monostearate (Aldo33), Polyoxyethylene Monolaurate (Atlas G-2129), and Polyoxyethylene Oil-based Ether (Atlas G-3930).

3. The preparation method according to claim 1, characterized in that, The shearing and disruption in step 1) is completed using a homogenizer at a speed of 2000-10000 r / min for a shearing time of 1-20 min; the ultrasonic disruption is completed using a cell disruptor for 0.5-10 min; the equipment available for preparing small droplets by spraying includes a sprayer, a humidifier, and a small spray bottle.

4. The preparation method according to claim 1, characterized in that, In step 3), precursor B includes one or more of the following: calcium chloride, calcium acetate, barium chloride, sodium chloride, ammonia, lithium nitrate, lithium chloride, lithium acetate, tris(hydroxymethyl)aminomethane, hydrogen peroxide, and ferric chloride. The solvent for the precursor B solution includes one or more of methanol, ethanol, isopropanol, and acetone; The concentration of the precursor B solution is 0.1-3 M.

5. The preparation method according to claim 1, characterized in that, The precooling time in step 3) is 5 min to 1 h.

6. The preparation method according to claim 1, characterized in that, In step 3), the reaction temperature is -40℃ to 20℃, and the reaction time is 1 to 24 h.

7. A hollow multi-shell material, characterized in that, The hollow multi-shell layer is obtained by any one of the preparation methods described in 1-6.

8. The hollow multi-shell material according to claim 7, characterized in that, The hollow multi-shell structure material is one or more of the following: calcium carbonate, barium sulfate, barium carbonate, silver chloride, iron hydroxide, lithium fluoride, polydopamine, and iron-tannic acid. The hollow multi-shell structure has 1-5 shells; the diameter is 0.2-3 micrometers; and the shell wall thickness is 20-200 nanometers.

9. The application of the hollow multi-shell material according to claim 7 or 8 in energy storage batteries, characterized in that... The hollow multi-shell material of claim 7 or 8 is added to the electrolyte and dispersed evenly by stirring or shaking to obtain an electrolyte containing the hollow multi-shell material additive.

10. The application of the hollow multi-shell material method according to claim 9 in energy storage batteries, characterized in that, The hollow multi-shell structure material is added to the electrolyte at a ratio of 0% to 20%, excluding 0%.

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