A lithium-loaded composite skeleton material and its preparation method and application

Abstract

The present invention discloses a lithium-loaded composite skeleton material and its preparation method and application. The lithium-loaded composite skeleton material is a thin film packaging structure encapsulating a plurality of hollow thin-walled nano-carbon balls. The inner wall of the hollow thin-walled nano-carbon balls is composited with low-lithium-deposition-overpotential nanoparticles. The thin film is a high-lithium-deposition-overpotential film layer, which is a single layer or multiple layers selected from a carbon layer, a polymer film layer, a solid electrolyte film layer, an oxide film layer, or an ion / electron mixed conductor film layer. The low-lithium-deposition-overpotential nanoparticles are defined as a single substance or compound having a reaction potential with lithium greater than 0V. The high-lithium-deposition-overpotential film layer is defined as a film layer having a lithium electrodeposition potential on its surface less than 0V. The inner wall of the lithium-loaded composite skeleton material in the present invention has a lower lithium deposition potential than the thin film, so that lithium ions can only penetrate the carbon wall and preferentially nucleate and deposit inside the hollow carbon balls, thereby achieving the encapsulation and continuous and uniform deposition / dissolution of lithium metal.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium metal battery electrode materials, and in particular relates to a lithium-loaded composite skeleton material and a preparation method and application thereof. Background Art

[0002] The negative electrode of a lithium metal battery is usually a single metal lithium or an electrode containing a single metal lithium. Unlike conventional lithium-ion batteries, the negative electrode in a lithium metal battery is charged and discharged in the form of deposition and dissolution rather than insertion and extraction. Its charge and discharge mechanism is: Charging: Li + +e=Li; discharge: Li-e=Li + Therefore, compared with lithium-ion batteries, lithium metal batteries are a completely new battery system with a different mechanism of action.

[0003] Lithium metal has an extremely high theoretical specific capacity of 3860 mAh g -1 With a minimum electrochemical potential of -3.04V (relative to a standard hydrogen electrode), lithium metal has long been considered the most promising anode material for next-generation high-energy secondary battery systems. However, lithium metal is highly reactive and prone to side reactions with the electrolyte, forming an uneven and unstable SEI film. Repeated deposition and dissolution processes increase the SEI's growth and thickness, reducing coulombic efficiency. Furthermore, the skeleton-less nature of lithium metal predisposes to significant volume effects and uncontrollable lithium dendrites during repeated charge and discharge, creating potential safety hazards and hindering its practical application.

[0004] Currently, constructing 3D carbon materials as host skeletons for lithium metal has been proven to be an effective means of suppressing the volume effect and reducing lithium dendrite growth. In particular, closed-structured carbon nanospheres not only effectively isolate the interfacial effects between lithium metal and the electrolyte, but also provide abundant cavities to support lithium metal. For example, Cui Yi et al. [Yan K, Lu Z, Lee H W, et al. Selective deposition and stable encapsulation of lithiμm through heterogeneous seeded growth [J]. Nature Energy, 2016, 1: 16010.] and [Wang H, Li Y., Li Y., et al. Wrinkled Graphene Cages as Hosts for High-Capacity Li Metal Anodes Shown by Cryogenic Electron Microscopy. [J]. Nano letters, 2019, 19: 1326-1335.] used gold nanoparticles to guide the selective deposition of lithium metal, resulting in a composite lithium anode with minimal interfacial side reactions and low volume effect. Wang Mingsheng et al. [Y W., PF, L X., et al. Stable Nano-Encapsulation of Lithiμm ThroughSeed-Free Selective Deposition for High-Performance Li Battery Anodes [J]. Advanced Energy Materials, 2020, 10: 1902956.] nanoencapsulated lithium metal with nitrogen-doped hollow carbon spheres to obtain a lithium metal anode with low interfacial effects and long-cycle stability. Although current research can achieve a relatively stable lithium metal anode to a certain extent, the volume effect and interfacial side reactions of the lithium metal anode are still relatively serious at practical current density and high lithium loading, making it impossible to maintain high coulombic efficiency and stable cycling, making it difficult to meet the performance requirements of commercial lithium metal anodes. Summary of the Invention

[0005] In response to the problems of severe interfacial side reactions and large volume effects in the existing lithium metal negative electrode during the cycle process, the present invention provides a lithium-loaded composite skeleton material, which aims to selectively induce lithium to be uniformly deposited in the inner cavity of the carbon composite skeleton, improve the uneven deposition of lithium under high current, reduce the volume effect and interfacial side reactions, and improve the cycle performance of the lithium metal negative electrode.

[0006] The second purpose of the present invention is to provide a method for preparing the lithium-loaded composite skeleton material.

[0007] The third purpose of the present invention is to provide an application of the lithium-loaded composite skeleton material.

[0008] A lithium-loaded composite skeleton material, comprising a thin film encapsulation structure encapsulating a plurality of hollow thin-walled carbon nanospheres, wherein the inner walls of the hollow thin-walled carbon nanospheres are composited with nanoparticles having a low lithium deposition overpotential, and the thin film is a high lithium deposition overpotential film layer, wherein the film layer is a single layer or a multilayer selected from a carbon layer, a polymer film layer, a solid electrolyte film layer, an oxide film layer, or an ion / electron mixed conductor film layer;

[0009] The low lithium overpotential nanoparticles are defined as nanoparticles with a lithium reaction potential greater than 0V (Vs.Li / Li + ) in elemental or compound form;

[0010] The high lithium deposition overpotential film layer is defined as a film layer that makes the lithium deposition potential on its surface less than 0V (Vs.Li / Li + ) film layer.

[0011] The lithium-loaded composite skeleton material provided by the present invention involves a high lithium deposition overpotential film layer, hollow thin-walled nano-carbon spheres, and the voids between the carbon spheres. The relationship between the high lithium deposition overpotential film layer and the nano-carbon spheres (primary particles) is an inclusive relationship. The nano-carbon spheres (primary particles) are first stacked into secondary particles, and then the high lithium deposition overpotential film layer encapsulates the secondary particles to form a whole. The voids appear between the nano-carbon spheres and between the nano-carbon spheres and the outer high lithium deposition overpotential film layer. Studies have found that the role of the voids is to effectively buffer the volume changes of the hollow thin-walled nano-carbon spheres during the lithium metal deposition / dissolution process, fundamentally solving the volume effect of the lithium metal negative electrode.

[0012] Preferably, the hollow thin-walled nanocarbon spheres contain lithiophilic functional groups, which are a combination of one or more nitrogen-containing, oxygen-containing, fluorine-containing, and sulfur-containing functional groups; more preferably, they are a combination of one or more nitrogen-containing and oxygen-containing functional groups, and further preferably, they are nitrogen-containing functional groups.

[0013] More preferably, the content of lithiophilic functional groups in the hollow thin-walled carbon nanospheres is 1 to 20.5 at.%, and even more preferably 2 to 15 at.%. Studies have found that within this range, they and the inner layer of low-lithiation overpotential nanoparticles form a good gradient lithiophilicity, which can significantly improve initial coulombic efficiency and cycling performance.

[0014] The present invention has found that the high-lithiation overpotential film layer of the secondary particle outer layer composite has a high nucleation overpotential, which is not conducive to the nucleation and growth of lithium on this film layer; while the functional groups of the low-lithiation overpotential nanoparticles and hollow thin-walled nanocarbon spheres all have a significant affinity for lithium metal. Further research has found that the lithiophilic functional groups can induce lithium to be evenly dispersed on the particle surface. In addition, the lithium-evolution potential of the inner wall of the primary particle is lower than that of the outer layer of the secondary particle, so that lithium ions are selectively induced to enter the carbon cavity and evenly deposited in the nanocarbon sphere and the inner cavity of the entire secondary particle. The multi-domain confined composite framework with gradient lithium affinity can achieve uniform deposition of metallic lithium, effectively inhibiting the formation of lithium dendrites.

[0015] Preferably, the hollow thin-walled carbon nanospheres are in at least one of a spherical shape, a rugby ball shape, a disc shape, a persimmon shape, and a red blood cell shape, and more preferably in a spherical shape.

[0016] Preferably, the number of the stacked hollow thin-walled carbon nanospheres is one or more. The number of the hollow thin-walled carbon nanospheres in the present invention is not limited and can be one or more.

[0017] Preferably, the particle size of the hollow thin-walled nanocarbon spheres is 10 to 990 nm; more preferably 50 to 950 nm, and even more preferably 100 to 900 nm.

[0018] Preferably, the shell thickness of the high lithium deposition overpotential film layer and the hollow thin-walled carbon nanospheres are both 0.1 to 100 nm, more preferably 0.5 to 90 nm, and even more preferably 1 to 80 nm.

[0019] Preferably, the low lithium deposition overpotential nanoparticles are lithium-intercalating compounds or simple substances that can alloy with lithium;

[0020] The lithium-insertable compound is Ag2O, Co3O4, NiO, ZnO, Cu x O,MgO,Ag2S,Cu2S,Ni x N,Cu3N2,Ni2P,Cu3P,CoP,ZnP,SnP,FePO4,Li x Mn2O4,Li x CoO2, one or more combinations thereof, more preferably Co3O4, ZnO, Cu x O, more preferably ZnO;

[0021] The elemental substance is a combination of one or more of graphite, boron, silver, gold, platinum, zinc, magnesium, cobalt, tin, germanium, silicon, aluminum, indium, and calcium, more preferably a combination of one or more of silver, gold, and zinc, and even more preferably silver.

[0022] More preferably, the particle size of the low lithium deposition overpotential nanoparticles is 0.1 to 100 nm, preferably 0.5 to 60 nm, and further preferably 0.8 to 30 nm.

[0023] Preferably, the content of the low lithium deposition overpotential nanoparticles is 2 to 20 at.%, more preferably 4 to 10 at.%.

[0024] Preferably, the composite form of the low lithium deposition overpotential nanoparticles and the inner wall of the hollow thin-walled nano-carbon spheres is in the form of dotting, inlaying or penetration, and more preferably in the form of inlaying.

[0025] Preferably, the film layer is a polymer film layer or an oxide film layer, and more preferably a polymer film layer.

[0026] Preferably, the carbon layer is a combination of one or more of a graphitized carbon layer and an amorphous carbon layer, and more preferably an amorphous carbon layer.

[0027] Preferably, the polymer is a combination of one or more of CMC-Li, lithium polyacrylate, zinc polyacrylate, magnesium polyacrylate, aluminum polyacrylate, lithium carboxymethyl cellulose, polyvinylidene fluoride, and poly(vinylidene fluoride-CO-hexafluoropropylene); more preferably, it is a combination of one or more of CMC-Li, lithium polyacrylate, zinc polyacrylate, magnesium polyacrylate, and aluminum polyacrylate; and even more preferably, it is a combination of one or more of CMC-Li and zinc polyacrylate.

[0028] Preferably, the oxide is an oxide having lithium ion conductivity, selected from a combination of one or more of aluminum oxide, titanium oxide, zirconium oxide, and germanium oxide, more preferably a combination of one or more of aluminum oxide and titanium oxide, and even more preferably aluminum oxide.

[0029] Preferably, the solid electrolyte is lithium germanium aluminum phosphate Li 1.5 Al 0.5 Ge 1.5 (PO4)3, garnet-type Li7La3Zr2O 12 、Li 1.4 Al 0.4 Ti 1.6 (PO4)3, lithium niobate, lithium zirconate, lithium phosphide, lithium nitride, lithium fluoride, lithium titanate, one or more combinations thereof, more preferably lithium germanium aluminum phosphate Li 1.5 Al 0.5 Ge 1.5 (PO4)3, garnet-type Li7La3Zr2O 12 , lithium phosphide, lithium nitride, lithium fluoride, one or more combinations thereof, more preferably lithium germanium aluminum phosphate Li 1.5 Al 0.5 Ge1.5 (PO4)3, lithium phosphide, or a combination of one or more thereof.

[0030] Preferably, the ion / electron mixed conductor is LiC6, Li 22 Si5、Li9Al l4 、Li 15 Ge4、Li 22 Sn5、CuLi x A combination of one or more of LiC6 and CuLi x A combination of one or more of .

[0031] The present invention also provides a method for preparing the above-mentioned lithium-loaded composite skeleton material, comprising the following steps:

[0032] Step 1: Template activation

[0033] placing the template in a surfactant solution for surface activation, and separating to obtain a surface-activated template;

[0034] The template is at least one of elemental silicon, silicon dioxide, titanium dioxide, zinc oxide, magnesium oxide, calcium oxide, and polyacrylamide (PAM), more preferably silicon dioxide; the average diameter of the silicon dioxide is 5 to 1000 nm, more preferably 5 to 600 nm;

[0035] The surfactant is at least one of sodium hydroxide, stannous chloride, PbCl2, and mercaptopropyl-trimethoxysilane, and is more preferably at least one of sodium hydroxide and stannous chloride;

[0036] The concentration of the surfactant in the surfactant solution is 0.005 to 0.5 mol / L, more preferably 0.01 to 0.2 mol / L;

[0037] Step 2: Composite low lithium deposition overpotential nanoparticles on the template surface

[0038] Compounding low lithium deposition overpotential nanoparticles on the surface of a surface-activated template to obtain surface-activated template@low lithium deposition overpotential nanoparticles;

[0039] The low-lithium overpotential nanoparticle composite method of the present invention can be prepared using conventional methods. For example, the composite method for Ag nanoparticles is as follows: a surface-activated SiO2 template is combined with an AgNO3 solution in the presence of a reducing agent to deposit uniform silver nanoparticles to obtain SiO2@Ag; the concentration of the AgNO3 solution is 0.002 to 0.1 mol / L; the reducing agent is at least one of formaldehyde, acetaldehyde, propionaldehyde, and glucose;

[0040] Another example is the composite method of ZnO nanoparticles: adding the surface activated template to a polyethylene glycol solution of Zn(NO3)2, and then adding a low concentration of alkali solution to obtain a surface activated template@ZnO, wherein the concentration of the Zn(NO3)2 is 0.00001 to 0.1 mol / L;

[0041] Another example is the composite method of Ni2P nanoparticles: adding a surface-activated SiO2 template to an aqueous solution of Ni(NO3)2, depositing uniform nickel nanoparticles under the action of a reducing agent to obtain Ni@SiO2, and further performing phosphating treatment in a PH3 gas phase to obtain SiO2@Ni2P, wherein the concentration of Ni(NO3)2 is 0.005-0.5 mol / L;

[0042] Another example is Cu x The composite method of N nanoparticles is as follows: the surface activated SiO2 template is added to the aqueous solution of Cu(NO3)2, and the uniform Cu nanoparticles are deposited under the action of a reducing agent to obtain SiO2@Cu, which is further treated with plasma at 400-500℃ for 2-5h in a H2 / N2 mixed atmosphere to obtain SiO2@Cu. x N, the concentration of Cu(NO3)2 is 0.001-0.1 mol / L;

[0043] For example, the composite method of Cu2S nanoparticles is: adding a surface-activated SiO2 template to an aqueous solution of Cu(NO3)2, uniformly depositing Cu nanoparticles under the action of a reducing agent to obtain SiO2@Cu, further treating it in an aqueous NaOH solution and reacting it with a Na2S solution to obtain SiO2@Cu2S, where the concentration of Cu(NO3)2 is 0.001~0.5mol / L.

[0044] Step 3: Carbon coating

[0045] The surface activated template@low lithium deposition overpotential nanoparticles are coated with a precursor carbon source to obtain surface activated template@low lithium deposition overpotential nanoparticles@carbon source;

[0046] The carbon coating method in the present invention adopts existing conventional methods, such as solution method, gas phase method, etc. to coat the precursor carbon source. For example, the dopamine hydrochloride coating method is as follows: SiO2@Ag is placed in a mixed solution of dopamine hydrochloride and trihydroxyaminomethane for in-situ polymerization, the pH is adjusted to 8.5, the dopamine hydrochloride monomer concentration is 0.1-100 g / L, more preferably 0.5-80 g / L, the in-situ polymerization temperature is 10-100°C, more preferably 20-50°C; the in-situ polymerization time is 5-100h, more preferably 10-48h; finally, SiO2@Ag@carbon source is obtained;

[0047] Another example of a resorcinol coating method is: SiO2@Ag is placed in a resorcinol solution for in-situ polymerization, with the resorcinol monomer concentration being 0.1-10 g / L, more preferably 0.2-5 g / L, to obtain SiO2@Ag@carbon source;

[0048] Step 4: Firing

[0049] Calcinate the surface activated template@low lithium deposition overpotential nanoparticles@carbon source under a protective atmosphere to obtain surface activated template@low lithium deposition overpotential nanoparticles@C;

[0050] Step 5: Remove the template

[0051] The surface activated template @ low lithium overpotential nanoparticles @C is placed in an etchant solution for template etching, and the template is removed to obtain hollow thin-walled nanocarbon spheres with low lithium overpotential nanoparticles composited on the inner wall;

[0052] Step 6: High lithium overpotential film encapsulates hollow thin-walled nanocarbon balls

[0053] Hollow thin-walled nano-carbon balls are stacked into secondary particles, and then a high lithium deposition overpotential film layer is compounded on the surface of the secondary particles to encapsulate them, thereby obtaining hollow thin-walled nano-carbon balls encapsulated by a single layer of high lithium deposition overpotential film layer; or high lithium deposition overpotential film layers are repeatedly compounded on a single layer of high lithium deposition overpotential film layer to form hollow thin-walled nano-carbon balls encapsulated by multiple layers of high lithium deposition overpotential film layers.

[0054] The composite packaging method of the high lithium overpotential film layer in the present invention can adopt existing conventional methods, and different composite packaging methods can be adopted according to the different film layers. For example, when the high lithium overpotential film layer is a single-layer polypropylene zinc layer, the hollow thin-walled nanocarbon spheres are first stacked into secondary particles by kneading, spray drying, etc., and then the particles are packaged with the polypropylene zinc high lithium overpotential film layer. During the packaging process, the mass ratio of zinc acetate to polyacrylic acid is controlled at 0.5 to 10, and more preferably 1 to 8; the concentration of the zinc acetate solution is 0.1 to 4 g / L, and the concentration of the polyacrylic acid solution is 0.1 to 4 g / L;

[0055] For example, when the high lithium overpotential film layer is a single-layer CMC-Li, the hollow thin-walled nanocarbon spheres are first stacked into secondary particles by kneading, spray drying, etc., and then the CMC-Na is acidified with a 5%-10% HCl ethanol solution for 1-10 hours, filtered, washed, and dried, and then replaced with a 5%-15% by mass LiOH solution for 5-20 hours to obtain a CMC-Li substitution degree of 0.5-0.8, which is filtered, washed, and dried; CMC-Li is dissolved in water at a concentration of 0.5%-10%, the solvent is water or acetonitrile, mixed with the secondary particles, and sprayed out by spray drying, the spray drying temperature is controlled to be 150-400°C, and the slurry upload speed is controlled to be 1-60mL / min;

[0056] For example, when the high lithium overpotential film layer is a single Al2O3 layer, the hollow thin-walled nanocarbon spheres are first stacked into secondary particles by kneading, spray drying, etc., and an Al2O3 electronic insulating thin layer is deposited on the surface of the secondary particles by atomic layer deposition. The atomic layer deposition temperature is 100-500°C, more preferably 100-400°C; the deposition time is 1-120s, more preferably 1-100s;

[0057] For example, when the high lithium overpotential membrane layer is a single-layer solid electrolyte layer, the hollow thin-walled nanocarbon spheres are first stacked into secondary particles by kneading, spray drying, etc., and then Li 1.5 Al 0.5 Ge 1.5 (PO4)3 is compounded on the surface of the secondary particles, and the compounding method is one or more combinations of immersion, kneading, electrodeposition, and evaporation, more preferably immersion, electrodeposition, and evaporation; the mass ratio of the secondary particles to the solid electrolyte is 10-50%, more preferably 15-45%;

[0058] For example, when the high lithium overpotential film layer is a single carbon layer, the hollow thin-walled nanocarbon spheres are first stacked into secondary particles by kneading, spray drying, etc., and then in situ polymerized with resorcinol or dopamine hydrochloride to form a closed thin-walled carbon layer with a thickness of 0.1 to 100 nm, more preferably 5 to 80 nm.

[0059] For example, when the high lithium overpotential membrane layer is a double-layer composite membrane layer, the hollow thin-walled nanocarbon balls are first stacked into secondary particles by kneading, spray drying, etc., and then the closed thin-walled carbon layer is in situ polymerized with resorcinol or dopamine hydrochloride, and then any one of CMC-Li, polypropylene zinc, Al2O3, solid electrolyte, mixed ion / electronic conductor layer, etc. is further used to continue compounding on the surface of the carbon layer to form a double-layer composite membrane structure.

[0060] The present invention also provides the application of the above-mentioned lithium-loaded composite skeleton material, which is used as a lithium-free negative electrode material for lithium-ion primary or secondary batteries after pretreatment;

[0061] Or after being reloaded with lithium metal, it can be used as a lithium negative electrode material or lithium supplement material for lithium metal primary or secondary batteries.

[0062] In the present invention, the pretreatment is to remove functional groups on the surface of the lithium-loaded composite skeleton material that are likely to cause lithium loss by physical or chemical methods. Conventional methods such as electrochemical methods and molten lithium infiltration methods can be used. For example, the lithium-loaded composite skeleton material is used as the counter electrode and the lithium metal foil is used as the sacrificial electrode to perform charge and discharge cycle pretreatment (charge and discharge activation). The charge and discharge voltage range is 0 to 1V, and the number of charge and discharge cycles is 1 to 10 times, and more preferably 1 to 5 times; for example, the molten liquid lithium is infiltrated into the lithium-loaded composite skeleton material for 1 to 20 seconds, and more preferably 1 to 10 seconds; the molten lithium atomization activation method can also be used, that is, the molten liquid lithium is sprayed and atomized and then rapidly reacted with the lithium-loaded composite skeleton material in a fluidized bed for 1 to 20 seconds, and more preferably 1 to 10 seconds.

[0063] The lithium metal is composited into the internal space of the lithium-loaded composite skeleton material by physical or chemical methods. Conventional methods such as electrochemical method and molten lithium infiltration method can be used. For example, the lithium-loaded composite skeleton material is used as the counter electrode and the lithium metal foil is used as the sacrificial electrode for discharge operation. The discharge cut-off capacity is 1 to 100 mAh / cm 2 , more preferably 1 to 50 mAh / cm 2 ;Discharge current is 0.1~10mA / cm 2 , more preferably 0.2 to 5 mA / cm 2 ; For example, the molten liquid lithium is infiltrated into the lithium-loaded composite skeleton material for 20 to 600 seconds, more preferably 20 to 300 seconds; the molten lithium atomization infiltration method can also be adopted, that is, the molten liquid lithium is sprayed and atomized and then circulated with the lithium-loaded composite skeleton material in a fluidized bed for 20 to 600 seconds, more preferably 20 to 300 seconds.

[0064] The construction of a lithium-loaded composite framework material effectively addresses the most challenging issues currently facing lithium metal anodes: the significant volume effect and severe interfacial side reactions during electrode cycling, which in turn lead to uncontrollable lithium dendrites and low Coulombic efficiency. The composite framework comprises thin-walled, internally lithiophilic hollow carbon nanospheres embedded with nanoparticles with a low lithium deposition overpotential, effectively inducing the selective deposition of lithium metal into the carbon cavity. The carbon shell effectively encapsulates the lithium metal, resisting electrolyte attack and minimizing interfacial side reactions. Furthermore, the carbon shell is incorporating various lithiophilic functional groups, enabling uniform lithium deposition. Secondary granulation aggregates the carbon nanospheres into secondary micronized particles, facilitating enhanced coating performance and lithium capacity. A high lithium deposition overpotential film encapsulates the secondary particles, suppressing volume changes in the primary particles during cycling while also creating an overpotential difference between the internal and external lithium deposition regions, forcing lithium metal deposition into the carbon cavity. The abundant voids within the secondary particles effectively buffer the expansion of the primary particles, ultimately ensuring electrode stability.

[0065] Beneficial effects of the present invention:

[0066] 1. The lithium-loaded composite skeleton material of the present invention has a stable structure and a large specific surface area, which can effectively reduce the local current density. As the host material of the lithium metal negative electrode, it can achieve high coulombic efficiency and long cycle life of the electrode at high current density.

[0067] 2. The lithium-loaded composite skeleton material of the present invention can induce deposition and multiple encapsulation of metallic lithium. The high lithium deposition overpotential film layer is equivalent to an artificial SEI film, which greatly reduces the contact between elemental lithium and the electrolyte, avoids the occurrence of cross-sectional side reactions, and significantly improves the electrochemical performance of lithium metal batteries, especially the cycle stability.

[0068] 3. The lithium-loaded composite skeleton material of the present invention has a good gradient lithium affinity. The abundant low lithium deposition overpotential nanoparticles in the inner cavity can effectively reduce the lithium nucleation overpotential. In addition, the high lithium deposition overpotential of the outer film layer inhibits the nucleation and growth of lithium. This high lithium deposition overpotential difference between the inner and outer layers encourages lithium ions to enter the cavity, achieving nucleation and uniform deposition of lithium metal within the hollow carbon skeleton cavity. In addition, the abundant interstices provided by the skeleton structure greatly mitigate the volume effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 This is the SEM image of the hollow thin-walled nanocarbon spheres prepared in Example 1.

[0070] Figure 2 Graphs showing the electrochemical performance of the lithium-loaded composite skeleton material prepared in Example 1 and the hollow carbon composite skeleton material containing no low lithium deposition overpotential nanoparticles prepared in Comparative Examples 1-2. DETAILED DESCRIPTION

[0071] The following is a detailed description of the preferred embodiments of the present invention, which does not constitute any limitation to the present invention. That is, the present invention is not limited to the following embodiments, and common modifications or replacement compounds in the art are included in the scope defined by the claims of this application.

[0072] Example 1

[0073] SiO2 spheres with an average diameter of 500 nm were configured into a 10 g / L sol, and a 0.05 mol / L stannous chloride solution was used. The volume ratio of SiO2 sol to stannous chloride solution was 1:2. The sol was activated at room temperature for 3 h, filtered, rinsed with deionized water, and dispersed in 100 ml of deionized water. 100 ml of 0.025 mol / L AgNO3 solution was added, and ammonia solution was added dropwise to prepare a silver ammonia solution. Then 125 ml of 0.01 mol / L glucose solution was added dropwise and stirred in a water bath at 50 ° C for 2 h to prepare SiO2@Ag. After cleaning, the SiO2@Ag was dispersed in 50ml of water, and 0.25g of dopamine and 0.25g of trihydroxyaminomethane were added. The pH was adjusted to 8.5, and the mixture was stirred at room temperature for 24 hours to obtain the SiO2@Ag@ carbon source. After filtration and cleaning, the mixture was mixed with water to form a suspension with a solid-to-liquid ratio of 40%. The spray temperature was set to 200°C to prepare secondary particles composed of stacked hollow thin-walled nanocarbon spheres. The secondary particles were cleaned and prepared into a 10g / L suspension. Resorcinol monomer was added to a concentration of 1g / L, and in situ polymerization was carried out under formaldehyde reduction to obtain a lithium-loaded composite skeleton material precursor. The temperature was then increased to 400°C at 5°C / min, then to 800°C at 1°C / min under high-purity argon, and calcined for 3 hours. Finally, the mixture was stirred in a 5 mol / L NaOH solution at 70°C in a water bath for 12 hours, filtered, washed, and dried to obtain a lithium-loaded composite skeleton material (wherein the low lithium deposition overpotential nanoparticles were Ag with an average particle size of 25 nm, and the high lithium deposition overpotential film layer was a carbon layer). In the lithium-loaded composite skeleton material prepared in this embodiment, the Ag loading was 10 at.%, the N loading was 10.4 at.%, and the carbon layer thickness was 30 nm.

[0074] Comparative Example 1-1

[0075] The same as Example 1, except that the SiO2 spheres were not subjected to surface activation treatment. The results showed that when the SiO2 spheres were not subjected to surface activation treatment, there were almost no silver nanoparticles on the surface of the SiO2 template, and in the final material, there were almost no silver nanoparticles on the inner wall of the hollow thin-walled nanocarbon spheres.

[0076] Comparative Example 1-2

[0077] The same as Example 1, the only difference is that the surface of the SiO2 template is not compounded with silver nanoparticles, and thus in the final material, there are no silver nanoparticles on the inner wall of the hollow thin-walled nanocarbon spheres.

[0078] Comparative Examples 1-3

[0079] The results were the same as in Example 1, except that no dopamine coating was performed. The Ag nanoparticles were scattered throughout the carbon layer cavity and not embedded in the carbon walls. The absence of dopamine coating can easily lead to incomplete carbon spheres, which cannot fully encapsulate lithium metal and can easily lead to subsequent interfacial side reactions.

[0080] Comparative Examples 1-4

[0081] The same as Example 1, except that the secondary particles are not coated with resorcinol in situ polymerization. The secondary particles are not coated with a carbon layer, so the volume effect and interface side reactions cannot be effectively suppressed.

[0082] Comparative Examples 1-5

[0083] The same as Example 1, except that the spray drying secondary granulation was not performed. The results showed that the nano-carbon spheres were in a monodisperse state.

[0084] Comparative Examples 1-6

[0085] The same as Example 1, except that the Ag nanoparticles were replaced with Cu nanoparticles, the results showed that there was little lithium metal deposition in the nanocarbon spheres.

[0086] Comparative Examples 1-7

[0087] The same as Example 1, except that the encapsulation film layer of the secondary particles is a thin film coating of Au. The results show that lithium metal tends to be deposited on the outside of the secondary particles, and there is almost no lithium metal in the carbon spheres.

[0088] The materials prepared in Example 1, Comparative Example 1-1, Comparative Example 1-2, Comparative Example 1-3, Comparative Example 1-4, Comparative Example 1-5, Comparative Example 1-6 and Comparative Example 1-7 were mixed with binder PVDF and acetylene black in a mass ratio of 8:1:1, and NMP was added to form a slurry and evenly coated on a copper foil. After drying, they were used as working electrodes, a metal lithium sheet was used as a counter electrode, and a button half-cell was assembled using 1M LiTFSI / DOL:DME (volume ratio = 1:1) containing 2% wt LiNO3 as the electrolyte. After activation, the battery was subjected to a charge and discharge cycle test. At 3 mA / cm 2 The current density is 1 mAh / cm 2 The charge and discharge cycle test was carried out, and the test results are shown in Table 1 below:

[0089] Table 1 Electrochemical performance results of materials obtained from Example 1, Comparative Example 1-1, Comparative Example 1-2, Comparative Example 1-3, Comparative Example 1-4, Comparative Example 1-5, Comparative Example 1-6 and Comparative Example 1-7

[0090]

[0091] Example 2

[0092] SiO2 balls with an average diameter of 500nm are configured into a 10g / L sol, and a stannous chloride solution with a concentration of 0.05mol / L is used. The volume ratio of SiO2 sol to stannous chloride solution is 1:2. The mixture is activated at room temperature for 3h, filtered, rinsed with deionized water, and dispersed in 100ml deionized water. The activated template is added to Zn(NO3)2 with a concentration of 0.1mol / L, and then polyethylene glycol solution is added. Subsequently, 0.0001mol / L KOH solution is added and stirred for 2h to obtain ZnO nanoparticles. 0.5g dopamine and 0.5g trihydroxyaminomethane are added, the pH is 8.5, and the SiO2@ZnO@ carbon source is obtained by stirring at room temperature for 24h. After filtration and cleaning, the mixture is prepared into a suspension with a solid-liquid ratio of 40% with water, and the spray temperature is set to 200℃ to prepare secondary particles of stacked hollow thin-walled nanocarbon balls. The secondary particles are cleaned and prepared into a 10g / L suspension, and resorcinol monomer is added to prepare its concentration of 1g / L, and in-situ polymerization is carried out under formaldehyde reduction to obtain a lithium-loaded composite skeleton material precursor. Then, the temperature is raised to 400°C at 5°C / min under high-purity argon, and then raised to 800°C at 1°C / min, and roasted for 3h. Finally, the mixture is stirred in a water bath at 70°C in a 5mol / L NaOH solution for 12h, filtered, washed, and dried to obtain a lithium-loaded composite skeleton material (wherein, the low lithium overpotential nanoparticles are ZnO with an average particle size of 30nm, and the high lithium overpotential film layer is a carbon layer). In the lithium-loaded composite skeleton material obtained in this embodiment, the ZnO loading is 15at.%, the N loading is 12at.%, and the carbon layer thickness is 40nm.

[0093] Comparative Example 2-1

[0094] The same as Example 2, except that no ZnO nanoparticle doping was performed. The results showed that there were no ZnO particles on the inner surface of the synthesized material.

[0095] Comparative Example 2-2

[0096] The same as Example 2, except that the spray drying secondary granulation is not performed.

[0097] Comparative Examples 2-3

[0098] The same as Example 2, except that the resorcinol in-situ polymerization coating is not performed.

[0099] The materials prepared in Example 2, Comparative Example 2-1, Comparative Example 2-2 and Comparative Example 2-3 were mixed with binder PVDF and acetylene black in a mass ratio of 8:1:1, and NMP was added to form a slurry and evenly coated on a copper foil. After drying, they were used as working electrodes, a metal lithium sheet was used as a counter electrode, and a button-type half-cell was assembled using 1MLiTFSI / DOL:DME (volume ratio = 1:1) containing 2% wt LiNO3 as the electrolyte. After activation, the battery was subjected to a charge and discharge cycle test. At 3 mA / cm 2 The current density is 1 mAh / cm 2 The charge and discharge cycle test was carried out, and the test results are shown in Table 2 below:

[0100] Table 2 Electrochemical performance results of the materials obtained in Example 2, Comparative Example 2-1, Comparative Example 2-2 and Comparative Example 2-3

[0101]

[0102] Example 3

[0103] SiO2 balls with an average diameter of 500nm were configured into a 10g / L sol, and a 0.05mol / L stannous chloride solution was used. The volume ratio of SiO2 sol to stannous chloride solution was 1:2. The mixture was activated at room temperature for 3h, filtered, rinsed with deionized water, and dispersed in 100ml deionized water. The activated template was added to a 0.1mol / L Cu(NO3)2 solution, and then an aqueous solution was added. Then, a formaldehyde solution was added and stirred for 2h to obtain SiO2@Cu. SiO2@Cu was obtained by plasma treatment at 450℃ for 2h in a H2 / N2 mixed atmosphere. x N, add 0.5g dopamine, 0.5g trihydroxyaminomethane, pH 8.5, stir at room temperature for 24h to obtain the SiO2@Cu x N@carbon source; after filtering and cleaning, it is mixed with water to form a suspension with a solid-liquid ratio of 40%, and the spray temperature is set to 200°C to prepare secondary particles of stacked hollow thin-walled nano-carbon balls. The secondary particles are washed and prepared into a 10g / L suspension, and resorcinol monomer is added to prepare its concentration of 1g / L. In situ polymerization is carried out under formaldehyde reduction to obtain a lithium-loaded composite skeleton material precursor. Then, the temperature is raised to 400°C at 5°C / min under high-purity argon, and then to 800°C at 1°C / min, and calcined for 3h. Finally, it is stirred in a water bath at 70°C in a 5mol / L NaOH solution for 12h, filtered, washed, and dried to obtain a lithium-loaded composite skeleton material (wherein, the low lithium overpotential nanoparticles are Cu with an average particle size of 35nm x N, the high lithium deposition overpotential film layer is a carbon layer). In the lithium-loaded composite skeleton material prepared in this embodiment, Cu x The N loading is 18 at.%, and the N loading is 11 at.%, respectively. The thickness of the carbon layer is 45 nm.

[0104] Comparative Example 3-1

[0105] Same as Example 2, except that Cu x N nanoparticle doping results show that there is no Cu on the inner surface of the synthesized material. x N particles.

[0106] Comparative Example 3-2

[0107] The same as Example 2, except that the spray drying secondary granulation is not performed.

[0108] Comparative Example 3-3

[0109] The same as Example 2, except that the resorcinol in-situ polymerization coating is not performed.

[0110] The materials obtained in Example 3, Comparative Example 3-1, Comparative Example 3-2 and Comparative Example 3-3 were mixed with binder PVDF and acetylene black in a mass ratio of 8:1:1, and then slurried with NMP and evenly coated on copper foil. After drying, they were used as working electrodes, and metal lithium sheets were used as counter electrodes. 1MLiTFSI / DOL:DME (volume ratio = 1:1) containing 2% wt LiNO3 was used as the electrolyte to assemble button-type half-cells. After activation, the cells were subjected to charge and discharge cycle tests. At 3 mA / cm 2 The current density is 1 mAh / cm 2 The charge and discharge cycle test was carried out, and the test results are shown in Table 3 below:

[0111] Table 3 Electrochemical performance results of the materials obtained in Example 3, Comparative Example 3-1, Comparative Example 3-2 and Comparative Example 3-3

[0112]

[0113] Example 4

[0114] SiO2 balls with an average diameter of 500nm are configured into a 10g / L sol, and a stannous chloride solution with a concentration of 0.05mol / L is used. The volume ratio of SiO2 sol to stannous chloride solution is 1:2. The solution is activated at room temperature for 3h, filtered, rinsed with deionized water, and dispersed in 100ml deionized water. The activated template is added to Ni(NO3)2 with a concentration of 0.1mol / L, and then an aqueous solution is added. Then, formaldehyde solution is added and stirred for 2h to obtain SiO2@Ni. After drying, sodium hypophosphate is used as a phosphorus source to decompose and phosphate at 350℃ for 2h to obtain SiO2@Ni2P. 0.5g dopamine and 0.5g trihydroxyaminomethane are added, the pH is 8.5, and the solution is stirred at room temperature for 24h to obtain the SiO2@Ni2P@carbon source. After filtering and washing, the solution is prepared into a suspension with a solid-liquid ratio of 40% with water, and the spray temperature is set to 200℃ to prepare secondary particles of stacked hollow thin-walled nanocarbon balls. The secondary particles are cleaned and prepared into a 10g / L suspension, and resorcinol monomer is added to prepare its concentration of 1g / L. In-situ polymerization is carried out under formaldehyde reduction to obtain a lithium-loaded composite skeleton material precursor. Then, the temperature is raised to 400°C at 5°C / min under high-purity argon, and then raised to 800°C at 1°C / min, and roasted for 3h. Finally, the mixture is stirred at 70°C in a water bath in a 5mol / L NaOH solution for 12h, filtered, washed, and dried to obtain a lithium-loaded composite skeleton material (wherein, the low lithium overpotential nanoparticles are Ni2P with an average particle size of 33nm, and the high lithium overpotential film layer is a carbon layer). In the lithium-loaded composite skeleton material obtained in this embodiment, the Ni2P loading is 19at.%, the N loading is 12at.%, and the carbon layer thickness is 34nm.

[0115] Comparative Example 4-1

[0116] The same as Example 2, except that no Ni2P nanoparticle doping was performed. The results showed that there were no Ni2P particles on the inner cavity surface of the synthesized material.

[0117] Comparative Example 4-2

[0118] The same as Example 2, except that the spray drying secondary granulation is not performed.

[0119] Comparative Example 4-3

[0120] The same as Example 2, except that the resorcinol in-situ polymerization coating is not performed.

[0121] The materials obtained in Example 4, Comparative Example 4-1, Comparative Example 4-2 and Comparative Example 4-3 were mixed with binder PVDF and acetylene black in a mass ratio of 8:1:1, and NMP was added to form a slurry and evenly coated on a copper foil. After drying, they were used as working electrodes, and a metal lithium sheet was used as a counter electrode. 1MLiTFSI / DOL:DME (volume ratio = 1:1) containing 2% wt LiNO3 was used as the electrolyte to assemble button-type half-cells. After activation, the battery was subjected to charge and discharge cycle tests. At 3 mA / cm 2 The current density is 1 mAh / cm 2 The charge and discharge cycle test was carried out, and the test results are shown in Table 4 below:

[0122] Table 4 Electrochemical performance results of the materials obtained in Example 4, Comparative Example 4-1, Comparative Example 4-2 and Comparative Example 4-3

[0123]

[0124] Example 5

[0125] SiO2 spheres with an average diameter of 500 nm were configured into a 10 g / L sol, and a 0.05 mol / L stannous chloride solution was used. The volume ratio of SiO2 sol to stannous chloride solution was 1:2. The SiO2 sol was activated at room temperature for 3 h, filtered, rinsed with deionized water, and dispersed in 100 ml of deionized water. The activated template was added to 0.1 mol / L Cu(NO3)2, and then the aqueous solution was added, followed by the formaldehyde solution. The SiO2@Cu was obtained by stirring for 2 h. The SiO2@Cu was further prepared at 0.005 mol / L After being treated in a NaOH aqueous solution for 10 minutes, it reacted with a Na2S solution to produce SiO2@Cu2S. 0.5g dopamine and 0.5g trihydroxyaminomethane were added, the pH was adjusted to 8.5, and the mixture was stirred at room temperature for 24 hours to obtain the SiO2@Cu2S@carbon source. After filtration and cleaning, the mixture was mixed with water to form a 40% solid-to-liquid suspension. The spray temperature was set at 200°C to produce secondary particles composed of stacked hollow thin-walled nanocarbon spheres. The secondary particles were cleaned and prepared into a 10g / L suspension. Resorcinol monomer was added to a concentration of 1g / L. In situ polymerization was carried out under formaldehyde reduction to obtain a lithium-loaded composite skeleton material precursor. The temperature was then increased to 400°C at 5°C / min, then to 800°C at 1°C / min under high-purity argon, and calcined for 3 hours. Finally, the mixture was stirred in a 5 mol / L NaOH solution at 70°C in a water bath for 12 h, filtered, washed, and dried to obtain a lithium-loaded composite skeleton material (wherein the low lithium deposition overpotential nanoparticles were Cu2S with an average particle size of 25 nm, and the high lithium deposition overpotential film layer was a carbon layer). In the lithium-loaded composite skeleton material prepared in this embodiment, the Cu2S loading was 15 at.%, the N loading was 10 at.%, and the carbon layer thickness was 40 nm.

[0126] Comparative Example 5-1

[0127] The same as Example 5, except that no Cu2S nanoparticle doping was performed. The results showed that there were no Cu2S particles on the inner surface of the synthesized material.

[0128] Comparative Example 5-2

[0129] The same as Example 5, except that the spray drying secondary granulation is not performed.

[0130] Comparative Example 5-3

[0131] The same as Example 5, except that the resorcinol in-situ polymerization coating is not performed.

[0132] The materials prepared in Example 5, Comparative Example 5-1, Comparative Example 5-2 and Comparative Example 5-3 were mixed with binder PVDF and acetylene black in a mass ratio of 8:1:1, and NMP was added to form a slurry and evenly coated on a copper foil. After drying, they were used as working electrodes, and a metal lithium sheet was used as a counter electrode. 1MLiTFSI / DOL:DME (volume ratio = 1:1) containing 2% wt LiNO3 was used as the electrolyte to assemble button-type half-cells. After activation, the battery was subjected to a charge and discharge cycle test. At 3 mA / cm 2 The current density is 1 mAh / cm 2 The charge and discharge cycle test was carried out, and the test results are shown in Table 5 below:

[0133] Table 5 Electrochemical performance results of the materials obtained in Example 5, Comparative Example 5-1, Comparative Example 5-2 and Comparative Example 5-3

[0134]

[0135] Example 6

[0136] The lithium-loaded composite skeleton material prepared in Example 1 (referred to as Example 1 sample, wherein the low lithium deposition overpotential nanoparticles are Ag and the high lithium deposition overpotential film layer is a single carbon layer) is further composited with a polyacrylate zinc film layer:

[0137] 0.2g of the sample from Example 1 was added to 100ml of a solution containing 0.1g / L and 4g / L zinc acetate, respectively. The mixture was vigorously stirred and dispersed, and polyacrylic acid solutions containing 0.1g / L and 4g / L were slowly added dropwise. The mass ratio of zinc acetate to polyacrylic acid was controlled at 183:144. After reaction and precipitation, the mixture was filtered and dried to obtain a lithium-loaded composite skeleton material (wherein the high lithium overpotential membrane layer was a double-layer structure of a carbon layer and a zinc polyacrylate membrane layer). The results showed that the composite skeleton materials synthesized with zinc acetate and polyacrylic acid solution concentrations of 0.1g / L and 4g / L had uniform and dense zinc polyacrylate membrane layers with thicknesses of 20nm and 50nm, respectively.

[0138] Example 7

[0139] The same as Example 6, except that no secondary carbon coating is performed, and the polypropylene zinc is directly coated on the surface of the stacked secondary particles, and the polypropylene layer is uniform, continuous and dense.

[0140] The materials prepared in Example 6 and Example 7 were mixed with binder PVDF and acetylene black in a mass ratio of 8:1:1, added with NMP to form a slurry, and evenly coated on a copper foil. After drying, they were used as working electrodes, and a metal lithium sheet was used as a counter electrode. A button-type half-cell was assembled using 1MLiTFSI / DOL:DME (volume ratio = 1:1) containing 2% wt LiNO3 as the electrolyte. After activation, the battery was subjected to a charge and discharge cycle test. 2 The current density is 1 mAh / cm 2 The charge and discharge cycle test was carried out, and the test results are shown in Table 6 below:

[0141] Table 6 Electrochemical performance results of the materials obtained in Example 6 and Example 7

[0142]

[0143] Example 8

[0144] The lithium-loaded composite skeleton material prepared in Example 1 (referred to as Example 1 sample, wherein the low lithium deposition overpotential nanoparticles are Ag and the high lithium deposition overpotential film layer is a single carbon layer) is further composited with a CMC-Li film layer:

[0145] CMC-Na was acidified with 8% HCl ethanol solution for 3h, filtered, washed and dried, and then replaced with 10% LiOH solution for 5h and 10h respectively, filtered, washed and dried. The substitution degree of CMC-Li was 0.66 and 0.77. CMC-Li was mixed with the sample of Example 1 to prepare a uniform slurry, wherein the mass fraction of CMC-Li was 5% and the mass fraction of the sample of Example 1 was 30%, dispersed in water, and sprayed out by spray drying, and the droplet upload speed was controlled to be 5ml / min. The CMC-Li coating thickness can be controlled to be 100nm. A lithium-loaded composite skeleton material was prepared (wherein the high lithium overpotential membrane layer was a double-layer structure of a carbon layer and a CMC-Li membrane layer).

[0146] Table 7 Electrochemical performance results of the materials obtained in Example 8

[0147]

[0148] Under different substitution degrees, half-cells were assembled and tested at 1 mA cm -2 ,1mAh cm -2 Under the conditions of good cycle life and high coulombic efficiency.

[0149] Example 9

[0150] The lithium-loaded composite skeleton material prepared in Example 1 (wherein the low lithium deposition overpotential nanoparticles are Ag and the high lithium deposition overpotential film layer is a single carbon layer) is further composited with a solid electrolyte lithium germanium aluminum phosphate Li 1.5 Al 0.5 Ge 1.5 (PO4)3 membrane layer:

[0151] Solid electrolyte lithium germanium aluminum phosphate Li 1.5 Al 0.5 Ge 1.5 The particle size of (PO4)3(LAGP) is 200nm and the coating thickness is 20μm; lithium aluminum germanium phosphate (LAGP) and polytetrafluoroethylene (PVDF) are mixed in a mass ratio of 80:20 and added to a nitrogen methyl pyrrolidone (NMP) solution. After grinding and stirring, a uniform slurry is obtained and coated on the surface of the electrode of the sample of Example 1. After drying in a drying oven at 60℃ for 8h, it is used as the working electrode, the metal lithium sheet is used as the counter electrode, and 1M LiTFSI / DOL:DME (volume ratio = 1:1) containing 5wt.% LiNO3 is used as the electrolyte for button cell assembly. After the battery is activated, the charge and discharge cycle test is carried out. At 3mA / cm 2 The current density is 1 mAh / cm 2 Perform charge and discharge cycle tests.

[0152] Table 8 Electrochemical performance results of the materials obtained in Example 9

[0153]

[0154] Example 10

[0155] The lithium-loaded composite skeleton material prepared in Example 1 (referred to as Example 1 sample, wherein the low lithium deposition overpotential nanoparticles are Ag and the high lithium deposition overpotential film layer is a single carbon layer) is further composited with an Al2O3 film layer:

[0156] 0.2g of the sample from Example 1 was mixed with a binder, PVDF, and acetylene black, in a mass ratio of 8:1:1. The mixture was slurried with NMP and evenly coated on copper foil. After drying in a hollow chamber, the mixture was placed in an atomic deposition system (Savannah S100 ALD system) in a mixed electrolyte of trimethylaluminum and deionized water at a temperature of 150°C and a pulse duration of 0.015s–15s–40s–0.015s–15s–40s to produce a lithium-loaded composite skeleton material (wherein the high lithium overpotential membrane layer comprises a double-layer structure of a carbon layer and an Al2O3 membrane layer). Results showed that the Al2O3 membrane layer of the composite skeleton material synthesized within a pulse duration of 110s had a thickness of 20nm and was uniform and dense.

[0157] Example 10-1

[0158] The same as Example 10, except that no secondary carbon coating is performed, and the Al2O3 film layer is directly coated on the surface of the stacked secondary particles. The Al2O3 film layer is uniform, continuous and dense.

[0159] The electrode sheets prepared in Example 10 and Example 10-1 were dried and used as working electrodes, and the metal lithium sheet was used as the counter electrode. 1M LiTFSI / DOL:DME (volume ratio = 1:1) containing 2% wt LiNO3 was used as the electrolyte to assemble button-type half-cells. After activation, the charge-discharge cycle test was carried out. 2 The current density is 1 mAh / cm 2 The charge and discharge cycle test was carried out, and the test results are shown in Table 9 below:

[0160] Table 9 Electrochemical performance results of the materials obtained in Example 10 and Example 10-1

[0161]

[0162] Example 11

[0163] The lithium-loaded composite skeleton material prepared in Example 1 (denoted as Example 1 sample, wherein the low lithium deposition overpotential nanoparticles are Ag and the high lithium deposition overpotential film layer is a single carbon layer) is further composited with an ion / electron mixed conductor layer:

[0164] 0.2 g of the sample of Example 1 was mixed with a binder PVDF and acetylene black in a mass ratio of 8:1:1, and NMP was added to form a slurry, and then the slurry was evenly coated on a copper foil. After hollow drying, the slurry was placed in an atomic deposition system (Savannah S100ALD system). In a silicon tetrachloride electrolyte, the temperature was 120 ° C, the pulse time was 1s–15s–30s–1s–15s–30s, and the electrode was cleaned with ethanol. It was used as a working electrode, a metal lithium sheet was used as a counter electrode, and a button half-cell was assembled with 1M LiTFSI / DOL:DME (volume ratio = 1:1) containing 2% wtLiNO3 as the electrolyte. After activation and lithium insertion at a voltage between 0-1V, a lithium-loaded composite skeleton material (wherein the high lithium overpotential film layer is a carbon layer and Li 22 The results show that the composite skeleton material synthesized by pulse 92s has a Li 22 The Si5 film layer is 25nm thick and is uniform and dense.

[0165] Example 11-1

[0166] Same as Example 11, except that no secondary carbon coating was performed.22 The Si5 film is directly coated on the surface of the stacked secondary particles, and the Li 22 The Si5 film layer is uniform, continuous and dense.

[0167] The electrode sheets prepared in Example 11 and Example 11-1 were dried and used as working electrodes, and the metal lithium sheet was used as the counter electrode. 1M LiTFSI / DOL:DME (volume ratio = 1:1) containing 2% wt LiNO3 was used as the electrolyte to assemble button-type half-cells. After activation, the cells were subjected to charge and discharge cycle tests. 2 The current density is 1 mAh / cm 2 The charge and discharge cycle test was carried out, and the test results are shown in Table 10 below:

[0168] Table 10 Electrochemical performance results of the materials obtained in Example 11 and Example 11-1

[0169]

[0170] Example 12

[0171] The lithium-loaded composite skeleton material prepared in Example 1 was mixed with polytetrafluoroethylene (PVDF) and conductive carbon in a mass ratio of 8:1:1 and added to a nitrogen-methylpyrrolidone (NMP) solution. A uniform slurry was obtained by grinding and stirring, and then coated on copper foil. After drying in a 60°C drying oven for 8 hours, it was used as the working electrode, a metal lithium sheet was used as the counter electrode, and a button cell was assembled using 1.0M LiPF6 in 89vol% 1:1w / wEC:DEC+10vol%FEC+1vol%VC as the electrolyte. After the battery was pretreated at 0-1V for 5 cycles and discharged to 0V to fully insert lithium, the battery was disassembled, the electrode was removed, and matched with the lithium iron phosphate positive electrode material to assemble a full battery. At the same time, the unpretreated lithium-loaded composite skeleton material was used as a control sample for corresponding charge and discharge cycle tests. The charge and discharge cycle test was carried out at 1C.

[0172] Table 11 Electrochemical performance results of the materials obtained in Example 12

[0173]

[0174] Example 13

[0175] The lithium-loaded composite skeleton material prepared in Example 1 was mixed with polytetrafluoroethylene (PVDF) and conductive carbon in a mass ratio of 8:1:1 and added to a nitrogen-methylpyrrolidone (NMP) solution. After grinding and stirring, a uniform slurry was obtained, which was coated on a copper foil and dried in a drying oven at 60°C for 8 hours as a working electrode. A metal lithium sheet was used as a counter electrode. A button cell was assembled with 1.0M LiPF6 in 89vol% 1:1w / wEC:DEC+10vol%FEC+1vol%VC as the electrolyte. After 5 cycles of activation at 0-1V, the battery was discharged to deposit 5 and 10mAh / cm 2 Lithium metal. The battery was disassembled, the electrodes removed, and then matched with lithium iron phosphate cathode material to assemble a full battery. Meanwhile, a pure metal lithium sheet was used as a control sample for corresponding charge and discharge cycle tests. The charge and discharge cycle tests were conducted at 1C.

[0176] Table 12 Electrochemical performance results of the materials obtained in Example 13

[0177]

Claims

1. A lithium-loaded composite skeleton material, characterized in that: The thin film packaging structure encapsulates a plurality of hollow thin-walled nano-carbon balls, wherein the inner wall of the hollow thin-walled nano-carbon balls is compounded with nanoparticles with low lithium deposition overpotential, and the thin film is a high lithium deposition overpotential film layer, wherein the film layer is a single layer or a multilayer, and the film layer is selected from a carbon layer, a polymer film layer, a solid electrolyte film layer, an oxide film layer or an ion / electron mixed conductor film layer; The low lithium overpotential nanoparticles are defined as lithium-intercalable compounds or single substances that can alloy with lithium and have a reaction potential with lithium greater than 0V (Vs.Li / Li+); wherein the lithium-intercalable compounds are Ag2O, Co3O4, NiO, ZnO, Cu x O, MgO, Ag2S, Cu2S, Ni x N, Cu x N, Ni2P, Cu3P, CoP, ZnP, SnP, FePO4, Li x Mn2O4、Li x A combination of one or more of CoO2; the element is a combination of one or more of graphite, boron, silver, gold, platinum, zinc, magnesium, cobalt, tin, germanium, silicon, aluminum, indium, and calcium; The hollow thin-walled nanocarbon spheres contain lithium-philic functional groups, which are nitrogen-containing functional groups. The high lithium deposition overpotential film layer is defined as a film layer that makes the electrodeposition potential of lithium on its surface less than 0V (Vs.Li / Li+); The carbon layer is a combination of one or more of a graphitized carbon layer and an amorphous carbon layer; The polymer is a combination of one or more of CMC-Li, lithium polyacrylate, zinc polyacrylate, magnesium polyacrylate, aluminum polyacrylate, lithium carboxymethyl cellulose, polyvinylidene fluoride, and poly(vinylidene fluoride-CO-hexafluoropropylene); The oxide is a combination of one or more of aluminum oxide, titanium oxide, zirconium oxide, and germanium oxide; The solid electrolyte is lithium germanium aluminum phosphate Li 1.5 Al 0.5 Ge 1.5 (PO4)3, garnet-type Li7La3Zr2O 12 、Li 1.4 Al 0.4 Ti 1.6 (PO4)3, one or more combinations of lithium niobate, lithium zirconate, lithium phosphide, lithium nitride, lithium fluoride, and lithium titanate; The ion / electron mixed conductor is LiC6, Li 22 Si5、Li9Al4、Li 15 Ge4、Li 22 Sn5、CuLi x one or more combinations of .

2. The lithium-loaded composite skeleton material according to claim 1, wherein: The hollow thin-walled carbon nanospheres are at least one of spherical, rugby, disc, persimmon, and red blood cell shapes; the particle size of the hollow thin-walled carbon nanospheres is 10 to 990 nm, and the number is one or more; The thickness of the shell of the hollow thin-walled nano-carbon sphere and the high lithium deposition overpotential film layer are both 0.1-100 nm.

3. The lithium-loaded composite skeleton material according to claim 1, wherein: The composite form of the low lithium deposition overpotential nanoparticles and the inner wall of the hollow thin-walled nanocarbon spheres is in the form of embellishment, inlay or penetration.

4. The lithium-loaded composite skeleton material according to claim 1, wherein: The carbon layer is obtained by carbonizing resorcinol-formaldehyde after polymerization.

5. A method for preparing the lithium-loaded composite skeleton material according to any one of claims 1 to 4, characterized in that: The steps include: Step 1: Template activation placing the template in a surfactant solution for surface activation, and separating to obtain a surface-activated template; The template is at least one of elemental silicon, silicon dioxide, titanium dioxide, zinc oxide, magnesium oxide, calcium oxide, and polyacrylamide; The surfactant is at least one of sodium hydroxide, stannous chloride, PbCl2, and mercaptopropyl-trimethoxysilane; Step 2: Composite low lithium deposition overpotential nanoparticles on the template surface Compounding low lithium deposition overpotential nanoparticles on the surface of a surface-activated template to obtain surface-activated template@low lithium deposition overpotential nanoparticles; Step 3: Carbon coating The surface activated template@low lithium deposition overpotential nanoparticles are coated with a precursor carbon source to obtain surface activated template@low lithium deposition overpotential nanoparticles@carbon source; the carbon source is dopamine hydrochloride; Step 4: Firing Calcinate the surface activated template@low lithium deposition overpotential nanoparticles@carbon source under a protective atmosphere to obtain surface activated template@low lithium deposition overpotential nanoparticles@C; Step 5: Remove the template The surface activated template @ low lithium overpotential nanoparticles @C is placed in an etchant solution for template etching, and the template is removed to obtain hollow thin-walled nanocarbon spheres with low lithium overpotential nanoparticles composited on the inner wall; Step 6: High lithium overpotential film encapsulates hollow thin-walled nanocarbon balls Hollow thin-walled nano-carbon balls are stacked into secondary particles, and then a high lithium deposition overpotential film layer is compounded on the surface of the secondary particles to encapsulate them, thereby obtaining hollow thin-walled nano-carbon balls encapsulated by a single layer of high lithium deposition overpotential film layer; or high lithium deposition overpotential film layers are repeatedly compounded on a single layer of high lithium deposition overpotential film layer to form hollow thin-walled nano-carbon balls encapsulated by multiple layers of high lithium deposition overpotential film layers.

6. The preparation method according to claim 5, characterized in that: In step 4, the protective atmosphere is Ar, N2 or He atmosphere; the heating rate of the calcination process is 1 to 10°C / min, the calcination temperature is 500 to 950°C, and the calcination time is 1 to 8 hours; In step five, the etchant is an acidic etchant, an alkaline etchant or an organic etchant; the acidic etchant is at least one of HF, HNO3, H2SO4, and HCl; the alkaline etchant is at least one of NaOH, KOH, LiOH, and Ca(OH)2; the organic etchant is at least one of ammonium bifluoride, CF4, and C4F8; the etching temperature of the template etching is 30 to 80°C, and the etching time is 6 to 24 hours.

7. Use of the lithium-loaded composite skeleton material according to any one of claims 1 to 4 or the lithium-loaded composite skeleton material prepared by the preparation method according to any one of claims 5 to 6, characterized in that: The lithium-loaded composite skeleton material is used as a lithium-free negative electrode material after pretreatment for lithium-ion primary or secondary batteries; Or after being loaded with metallic lithium, it can be used as a lithium negative electrode material or lithium supplement material for lithium metal primary or secondary batteries.

8. The use according to claim 7, characterized in that: The pretreatment is to remove functional groups on the surface of the lithium-loaded composite skeleton material that are prone to lithium loss by physical or chemical methods, and is selected from one of the following methods: electrochemical method, molten lithium infiltration method, and molten lithium atomization activation method; the molten lithium atomization activation method is to spray and atomize molten liquid lithium and then react it with the lithium-loaded composite skeleton material in a fluidized bed to quickly react to remove functional groups on the surface of the lithium-loaded composite skeleton material that are prone to lithium loss.

9. The use according to claim 7, characterized in that: The loaded metallic lithium is compounded into the internal space of the lithium-loaded composite skeleton material by a physical or chemical method, selected from one of an electrochemical method, a molten lithium infiltration method, and a molten lithium atomization infiltration method; the molten lithium atomization infiltration method is to spray and atomize molten liquid lithium and then react it with the lithium-loaded composite skeleton material in a fluidized bed in a cycle to compound the lithium metal into the internal space of the lithium-loaded composite skeleton material.

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