CN114142013A - Lithium-loaded composite framework material and preparation method and application thereof - Google Patents

Lithium-loaded composite framework material and preparation method and application thereof Download PDF

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CN114142013A
CN114142013A CN202111442827.4A CN202111442827A CN114142013A CN 114142013 A CN114142013 A CN 114142013A CN 202111442827 A CN202111442827 A CN 202111442827A CN 114142013 A CN114142013 A CN 114142013A
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lithium
overpotential
film layer
layer
carbon
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赖延清
洪波
姜怀
赖俊全
李劼
周言根
张治安
张凯
覃富荣
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Central South University
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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Abstract

The invention discloses a lithium-carrying composite framework material and a preparation method and application thereof, wherein the lithium-carrying composite framework material is a film packaging structure with a plurality of hollow thin-wall carbon nanospheres packaged inside, the inner walls of the hollow thin-wall carbon nanospheres are compounded with low-lithium-separation overpotential nanoparticles, the film is a high-lithium-separation overpotential film layer, the film layer is a single layer or multiple layers, 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-evolution overpotential nano-particle is defined as a simple substance or a compound with a reaction potential of more than 0V with lithium; the high lithium extraction overpotential film layer is defined as a film layer which enables lithium to have an electrodeposition potential of less than 0V on the surface thereof. Compared with a film, the inner wall of the lithium-loaded composite framework material has lower lithium precipitation potential, so that lithium ions can only penetrate through the carbon wall to preferentially nucleate and deposit in the hollow carbon sphere, and the encapsulation and continuous and uniform deposition/dissolution of lithium metal are realized.

Description

Lithium-loaded composite framework material and preparation method and application thereof
Technical Field
The invention belongs to the technical field of lithium metal battery electrode materials, and particularly relates to a lithium-loaded composite framework material and a preparation method and application thereof.
Background
The negative electrode of a lithium metal battery is usually a metallic lithium simple substance or an electrode containing a metallic lithium simple substance, different from a conventional lithium ion battery, in the lithium metal battery, the negative electrode is charged and discharged in a deposition and dissolution manner instead of being inserted and removed, and the charging and discharging mechanism is as follows: charging of Li++ e ═ Li; discharge Li-e ═ Li+. Therefore, lithium metal batteries are a completely new battery system with a different mechanism of action than lithium ion batteries.
The lithium metal has extremely high theoretical specific capacity of 3860mAh g-1The lowest electrochemical potential, 3.04V (relative to a standard hydrogen electrode), has been considered to be the most potential negative electrode material for next generation high energy secondary battery systems. However, lithium metal has strong activity, side reaction is easy to occur with electrolyte, the formed SEI film is uneven and unstable, SEI is increased and thickened continuously in the repeated deposition/dissolution process, and the coulombic efficiency is reduced; on the other hand, the non-skeleton nature of lithium metal is easy to generate huge volume effect and uncontrollable lithium dendrite in the process of repeated charge and discharge, thereby causing potential safetyHidden troubles hinder the practical use of the composition.
The construction of 3D carbon materials as host frameworks for lithium metal has been demonstrated to be an effective means of inhibiting the volume effect and reducing lithium dendrite growth. Particularly, the nano carbon spheres with the closed structures can effectively isolate the interface effect of lithium metal and electrolyte, and can provide abundant cavities to bear the lithium metal. For example, erect et al [ Yan K, Lu Z, Lee H W, et al.Selective deposition and stable encapsulation of lithihi μm through Graphene feedstock [ J ]. Nature Energy,2016,1:16010 ] ], [ Wang H, LiY., Li Y., et al.Wrinkled Graphene catalysts as Hosts for High-Capacity Li Metal Anodes Shown by Cryogenic Electron Microscopy [ J ]. NaNO applicators, 2019,19: 1326-. Wang Ming et al [ Y W., P F, L X., et al, Stable Nano-Encapsulation for High-Performance Li batteries Materials [ J ]. Advanced Energy Materials,2020,10:1902956 ] obtained lithium metal negative electrode with low interface effect and long cycle stability by Nano-Encapsulation of lithium metal Through nitrogen-doped hollow carbon spheres. Although current research can obtain a stable lithium metal negative electrode to a certain extent, under practical current density and high lithium loading capacity, the volume effect and the interface side reaction of the lithium metal negative electrode are still serious, high coulombic efficiency and stable circulation cannot be maintained, and the performance requirement of a commercial lithium metal negative electrode is difficult to meet.
Disclosure of Invention
The invention provides a lithium-carrying composite framework material aiming at solving the problems of serious interface side reaction and large volume effect of the conventional lithium metal negative electrode in the circulating process, and aims to selectively induce lithium to be uniformly deposited in an inner cavity of a carbon composite framework, improve the deposition nonuniformity of the lithium under large current, reduce the volume effect and the interface side reaction and improve the circulating performance of the lithium metal negative electrode.
The second purpose of the invention is to provide a preparation method of the lithium-loaded composite framework material.
The third purpose of the invention is to provide the application of the lithium-carrying composite framework material.
A lithium-carrying composite skeleton material is a film packaging structure with a plurality of hollow thin-wall carbon nanospheres packaged inside, the inner walls of the hollow thin-wall carbon nanospheres are compounded with low-lithium-evolution overpotential nanoparticles, the film is a high-lithium-evolution overpotential film layer, the film layer is a single layer or a plurality of layers, 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 extraction overpotential nanoparticles are defined as having a reaction potential with lithium greater than 0V (Vs. Li/Li)+) The simple substance or compound of (a);
the high lithium extraction overpotential film layer is defined to make the electrodeposition potential of lithium on the surface of the film layer less than 0V (Vs+) The film layer of (2).
The invention provides a lithium-carrying composite framework material, and relates to a high-lithium-separation overpotential film layer, hollow thin-wall carbon nanospheres and gaps among the carbon nanospheres, wherein the relationship between the high-lithium-separation overpotential film layer and the carbon nanospheres (primary particles) is an inclusion relationship, the carbon nanospheres (primary particles) are firstly stacked into secondary particles, and then the high-lithium-separation overpotential film layer encapsulates the secondary particles to form a whole. The gaps are shown between the carbon nanospheres and the outer high lithium-extraction overpotential film layer. Researches show that the gap has the function of effectively buffering the volume change of the hollow thin-wall carbon nanospheres in the lithium metal deposition/dissolution process, and the volume effect of the lithium metal cathode is fundamentally solved.
Preferably, the hollow thin-walled carbon nanospheres contain lithium-philic functional groups, and the lithium-philic functional groups are one or a combination of more of nitrogen-containing functional groups, oxygen-containing functional groups, fluorine-containing functional groups and sulfur-containing functional groups; further preferred are combinations of one or more of nitrogen-containing and oxygen-containing functional groups, and still further preferred are nitrogen-containing functional groups.
More preferably, the content of the lithium-philic functional group in the hollow thin-wall carbon nanospheres is 1-20.5 at%; further preferably 2 to 15 at.%. Research shows that under the control of the range, the gradient lithium affinity is good with the low lithium extraction overpotential nano particles in the inner layer, and the initial coulombic efficiency and the cycle performance can be obviously improved.
The research of the invention finds that the high lithium extraction overpotential film compounded on the outer layer of the secondary particles has higher nucleation overpotential, which is not beneficial to the nucleation and growth of lithium on the film; the functional groups of the low-lithium-evolution overpotential nano particles and the hollow thin-wall nano carbon spheres have obvious lithium affinity to lithium metal, and further research finds that the lithium affinity functional groups can induce lithium to be uniformly dispersed on the surfaces of the particles, and the lithium-evolution potential on the inner wall of the primary particles is lower than the lithium-evolution potential on the outer layer of the secondary particles, so that lithium ions are selectively induced to enter a carbon cavity and are uniformly deposited in the nano carbon spheres and the inner cavity of the whole secondary particle. The multi-confinement composite framework with gradient lithium affinity can realize uniform deposition of metal lithium and effectively inhibit formation of lithium dendrites.
Preferably, the hollow thin-wall carbon nanospheres are in at least one of a spherical shape, an rugby shape, a disc shape, a persimmon cake shape and a red blood cell shape, and more preferably are in a spherical shape.
Preferably, the number of the hollow thin-walled carbon nanocapsules stacked is 1 or more, and the number of the hollow thin-walled carbon nanocapsules in the present invention is not limited, and may be 1 or more.
Preferably, the particle size of the hollow thin-wall carbon nanospheres is 10-990 nm; more preferably 50 to 950nm, and still more preferably 100 to 900 nm.
Preferably, the thickness of the shell of each of the high lithium extraction overpotential film layer and the hollow thin-wall carbon nanospheres is 0.1-100 nm, more preferably 0.5-90 nm, and still more preferably 1-80 nm.
Preferably, the low lithium extraction over-potential nanoparticles are lithium intercalatable compounds or simple substances capable of being alloyed with lithium;
the lithium embeddable compound is Ag2O,Co3O4,NiO,ZnO,CuxO,MgO,Ag2S,Cu2S,NixN,Cu3N2,Ni2P,Cu3P,CoP,ZnP,SnP,FePO4,LixMn2O4,LixCoO2More preferably Co3O4、ZnO、CuxO, more preferably ZnO;
the simple substance is one or a combination of more of graphite, boron, silver, gold, platinum, zinc, magnesium, cobalt, tin, germanium, silicon, aluminum, indium and calcium, more preferably one or a combination of more of silver, gold and zinc, and even more preferably silver.
More preferably, the particle size of the low-lithium-evolution overpotential nanoparticles is 0.1 to 100nm, preferably 0.5 to 60nm, and even more preferably 0.8 to 30 nm.
Preferably, the content of the low-lithium-extraction overpotential nanoparticles is 2 to 20 at.%, more preferably 4 to 10 at.%.
Preferably, the low-lithium-evolution overpotential nanoparticles and the inner wall of the hollow thin-wall carbon nanosphere are compounded in a decoration, embedding or penetrating mode, and further preferably in an embedding mode.
Preferably, the film layer is a polymer film layer or an oxide film layer, and more preferably a polymer film layer.
Preferably, the carbon layer is one or a combination of graphitized carbon layer and amorphous carbon layer, and more preferably is an amorphous carbon layer.
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, poly (vinylidene fluoride-CO-hexafluoropropylene); further preferably one or more of CMC-Li, lithium polyacrylate, zinc polyacrylate, magnesium polyacrylate and aluminum polyacrylate; still more preferably one or a combination of more of CMC-Li and zinc polyacrylate.
Preferably, the oxide is an oxide having a lithium ion conducting ability, and is selected from one or more of alumina, titania, zirconia, and germania, more preferably from one or more of alumina and titania, and still more preferably from alumina.
Preferably, the solid electrolyte is lithium aluminum germanium phosphateLi1.5Al0.5Ge1.5(PO4)3Garnet type Li7La3Zr2O12、Li1.4Al0.4Ti1.6(PO4)3One or a combination of more of lithium niobate, lithium zirconate, lithium phosphide, lithium nitride, lithium fluoride and lithium titanate, and more preferably lithium aluminum germanium phosphate Li1.5Al0.5Ge1.5(PO4)3Garnet type Li7La3Zr2O12A combination of one or more of lithium phosphide, lithium nitride and lithium fluoride, more preferably lithium aluminum germanium phosphate Li1.5Al0.5Ge1.5(PO4)3And lithium phosphide.
Preferably, the ion/electron mixed conductor is LiC6、Li22Si5、Li9All4、Li15Ge4、Li22Sn5、CuLixMore preferably LiC6And CuLixOne or more of the above.
The invention also provides a preparation method of the lithium-carrying composite framework material, which comprises the following steps:
the method comprises the following steps: template activation
Placing the template in a solution of a surfactant for surface activation, and separating to obtain a surface activated template;
the template is at least one of simple substance silicon, silicon dioxide, titanium dioxide, zinc oxide, magnesium oxide, calcium oxide and Polyacrylamide (PAM), and is further preferably silicon dioxide; the average diameter of the silicon dioxide is 5-1000 nm, and the preferable range is 5-600 nm;
the surface active agent is sodium hydroxide, stannous chloride and PbCl2At least one of mercaptopropyl-trimethoxysilane, and more preferably at least one of sodium hydroxide and stannous chloride;
the concentration of the surfactant in the solution of the surfactant is 0.005-0.5 mol/L, and more preferably 0.01-0.2 mol/L;
step two: template surface composite low-precipitation lithium overpotential nano-particles
Compounding the low-lithium-extraction overpotential nanoparticles on the surface of the surface-activated template to obtain surface-activated template @ low-lithium-extraction overpotential nanoparticles;
the low lithium-separation overpotential nano particle compound mode in the invention adopts the existing conventional method. For example, the compounding mode of the Ag nano particles is as follows: surface-activated SiO2Template and AgNO3The solution is deposited with even silver nano particles under the action of a reducing agent to obtain SiO2@ Ag; the AgNO3The concentration of the solution is 0.002-0.1 mol/L; the reducing agent is at least one of formaldehyde, acetaldehyde, propionaldehyde and glucose;
for another example, the compounding mode of the ZnO nanoparticles is as follows: adding a surface activated template to Zn (NO)3)2Followed by addition of a low concentration of alkali solution to the polyethylene glycol solution of (2) to obtain a surface-activated template @ ZnO, said Zn (NO)3)2The concentration of (A) is 0.00001-0.1 mol/L;
and then for example Ni2The compounding mode of the P nano particles is as follows: surface-activated SiO2Template addition to Ni (NO)3)2In the aqueous solution of (A), Ni @ SiO is obtained by depositing uniform nickel nano particles under the action of a reducing agent2Further at pH3Phosphating in the gas phase to obtain SiO2@Ni2P, said Ni (NO)3)2The concentration of (A) is 0.005-0.5 mol/L;
e.g. CuxThe compounding mode of the N nano particles is as follows: surface-activated SiO2Template addition to Cu (NO)3)2In the aqueous solution of (A), depositing uniform Cu nanoparticles under the action of a reducing agent to obtain SiO2@ Cu, further at H2/N2Under the mixed atmosphere, the SiO is obtained after the plasma treatment at 400-500 ℃ for 2-5h2@CuxN, said Cu (NO)3)2The concentration of (A) is 0.001-0.1 mol/L;
e.g. Cu2The compounding mode of the S nano particles is as follows: surface-activated SiO2Template addition to Cu (NO)3)2In the aqueous solution of (A), depositing uniform Cu nanoparticles under the action of a reducing agent to obtain SiO2@ Cu, further treated with aqueous NaOH solution and then treated with Na2S solution reacts to obtain SiO2@Cu2S, said Cu (NO)3)2The concentration of (b) is 0.001-0.5 mol/L.
Step three: carbon coating
Carrying out surface coating on the surface-activated template @ low-analysis lithium overpotential nano particle with a precursor carbon source to obtain the surface-activated template @ low-analysis lithium overpotential nano particle @ carbon source;
the carbon coating method in the invention adopts the conventional method, such as a solution method, a gas phase method and the like, to coat the precursor carbon source, and for example, the dopamine hydrochloride coating method comprises the following steps: mixing SiO2The method comprises the following steps of putting @ Ag into a mixed solution of dopamine hydrochloride and trihydroxyaminomethane for in-situ polymerization, adjusting the pH to 8.5, wherein the concentration of dopamine hydrochloride monomer is 0.1-100 g/L, preferably 0.5-80 g/L, and the temperature of in-situ polymerization is 10-100 ℃, preferably 20-50 ℃; the time of in-situ polymerization is 5-100 h, and preferably 10-48 h; finally obtaining SiO2@ Ag @ carbon source;
for another example, the resorcinol coating method comprises the following steps: mixing SiO2The @ Ag is put in a resorcinol solution for in-situ polymerization, the concentration of resorcinol monomer is 0.1-10 g/L, more preferably 0.2-5 g/L, and SiO is obtained2@ Ag @ carbon source;
step four: roasting
Roasting the surface-activated template @ low-lithium-extraction overpotential nano particle @ carbon source in a protective atmosphere to obtain a surface-activated template @ low-lithium-extraction overpotential nano particle @ C;
step five: stripper plate
Placing the surface-activated template @ low-lithium-extraction overpotential nano particle @ C in an etchant solution for template etching, and performing template stripping treatment to obtain hollow thin-wall carbon nanospheres with low-lithium-extraction overpotential nano particles compounded on the inner walls;
step six: hollow thin-wall nano carbon ball packaged by high-precipitation lithium overpotential film layer
Stacking the hollow thin-wall carbon nanospheres into secondary particles, and compounding the high-lithium-separation overpotential film layer on the surface of the secondary particles to encapsulate the secondary particles to obtain single-layer high-lithium-separation overpotential film layer encapsulated hollow thin-wall carbon nanospheres; or the high lithium extraction overpotential film layer is repeatedly compounded on the single-layer high lithium extraction overpotential film layer to form the hollow thin-wall carbon nanosphere packaged by the multiple-layer high lithium extraction overpotential film layers.
The composite packaging mode of the high lithium extraction overpotential film layer in the invention can be realized by adopting the conventional method, and different composite packaging modes can be adopted according to different film layers. For example, when the high lithium extraction overpotential film layer is a single-layer polypropylene zinc layer, the hollow thin-wall carbon nanospheres are firstly stacked into secondary particles by kneading, spray drying and other modes, and then the secondary particles are packaged by the polypropylene zinc high lithium extraction overpotential film layer, wherein the mass ratio of zinc acetate to polyacrylic acid is controlled to be 0.5-10, and the preferable range is 1-8 in the packaging process; the concentration of the zinc acetate solution is 0.1-4 g/L, and the concentration of the polyacrylic acid solution is 0.1-4 g/L;
for example, when the high lithium extraction overpotential film layer is a single-layer CMC-Li, firstly stacking hollow thin-wall carbon nanospheres into secondary particles by kneading, spray drying and other modes, then acidifying CMC-Na by adopting a 5-10% HCl ethanol solution for 1-10h, filtering, washing and drying, then replacing by using a 5-15% LiOH solution by mass for 5-20h to obtain a CMC-Li substitution degree of 0.5-0.8, filtering, washing and drying; dissolving CMC-Li in water at a concentration of 0.5-10%, mixing the solvent of water or acetonitrile with the secondary particles, spraying out by spray drying, controlling the temperature of the spray drying at 150-;
for example, when the high lithium-precipitating overpotential film layer is a single layer of Al2O3When in lamination, the hollow thin-wall carbon nanospheres are firstly stacked into secondary particles by adopting the modes of kneading, spray drying and the like, and Al is deposited by using an atomic layer2O3An electronic insulation thin layer is arranged on the surface of the secondary particles, and the atomic layer deposition temperature is 100-500 ℃, and further preferably 100-400 ℃; the deposition time is 1-120 s, and more preferably 1-100 s;
for example, when the high lithium-evolution overpotential film layer isWhen the single-layer solid electrolyte layer is formed, hollow thin-wall carbon nanospheres are stacked into secondary particles by kneading, spray drying and the like, and Li is used1.5Al0.5Ge1.5(PO4)3Compounding on the surface of the secondary particles, wherein the compounding method is one or more of soaking, kneading, electrodeposition and evaporation, and further preferably soaking, electrodeposition and evaporation; the mass ratio of the secondary particles to the solid electrolyte is 10-50%, and the preferable mass ratio is 15-45%;
for example, when the high lithium extraction overpotential film layer is a single-layer carbon layer, hollow thin-wall carbon nanospheres are stacked into secondary particles by kneading, spray drying and the like, and resorcinol or dopamine hydrochloride is further used for in-situ polymerization to coat the closed thin-wall carbon layer, wherein the thickness is 0.1-100 nm, and the preferable thickness is 5-80 nm;
for example, when the high lithium extraction overpotential film layer is a double-layer composite film layer, hollow thin-wall carbon nanospheres are stacked into secondary particles by kneading, spray drying and the like, resorcinol or dopamine hydrochloride is further used for in-situ polymerization to coat the closed thin-wall carbon layer, and CMC-Li, polypropylene zinc and Al are further used2O3Any one of the solid electrolyte, the mixed ion/electronic conductor layer and the like is continuously compounded on the surface of the carbon layer to form a double-layer composite film layer structure.
The invention also provides the application of the lithium-carrying composite framework material, and the lithium-carrying composite framework material is used as a lithium-free negative electrode material after being pretreated and is used for a lithium ion primary or secondary battery;
or the lithium metal is loaded to be used as a lithium negative electrode material or a lithium supplement material for a lithium metal primary or secondary battery.
In the invention, the pretreatment is to remove functional groups which are easy to cause lithium loss on the surface of the lithium-carrying composite framework material by a physical or chemical method, and conventional methods such as an electrochemical method, a molten lithium immersion method and the like can be adopted, for example, the lithium-carrying composite framework material is used as a counter electrode, lithium metal foil is used as a sacrificial electrode, and the pretreatment (charge-discharge activation) of charge-discharge cycle is carried out, wherein the charge-discharge voltage range is 0-1V, and the number of charge-discharge cycles is 1-10, and more preferably 1-5; then, soaking the lithium-carrying composite framework material with the molten liquid lithium for 1-20 s, and preferably for 1-10 s; or a molten lithium atomization activation method can be adopted, namely molten liquid lithium is sprayed and atomized to rapidly react with the lithium-carrying composite framework material in a fluidized bed for 1-20 s, and the further optimization is 1-10 s.
The lithium metal complex is formed by physically or chemically complexing the lithium metal in the internal space of the lithium-loaded composite skeleton material by conventional methods such as electrochemical method and molten lithium infiltration method, for example, the lithium-loaded composite skeleton material is used as a counter electrode, the lithium metal foil is used as a sacrificial electrode, and the discharge cutoff capacity is 1-100 mAh/cm2More preferably 1 to 50mAh/cm2(ii) a The discharge current is 0.1-10 mA/cm2More preferably 0.2 to 5mA/cm2(ii) a Then, for example, the molten liquid lithium is infiltrated into the lithium-carrying composite framework material for 20 to 600 seconds, and the preferable time is 20 to 300 seconds; or a molten lithium atomization infiltration method can be adopted, namely molten liquid lithium is sprayed and atomized and then reacts with the lithium-carrying composite framework material in a fluidized bed for 20-600 s in a circulating manner, and the preferable time is 20-300 s.
The construction of the lithium-carrying composite framework material can effectively solve the most troublesome problems of the lithium metal negative electrode at present, namely the problems of uncontrollable lithium dendrites and low coulombic efficiency caused by huge volume effect and serious interface side reaction in the electrode circulation process. The inner wall of the lithium-philic thin-wall nano hollow carbon sphere in the composite framework is embedded with the nano particles with low lithium extraction overpotential, so that lithium metal is effectively induced to be selectively deposited in the carbon cavity, the carbon shell can play a good role in packaging the lithium metal, the corrosion of electrolyte is refused, and the interface side reaction is reduced. Meanwhile, various lithium-philic functional groups are compounded on the carbon shell, so that the deposition of lithium can be uniform. The carbon nanospheres are aggregated into secondary micron particles through secondary granulation, so that higher coating performance and lithium capacity are facilitated. The high-precipitation lithium overpotential film encapsulates secondary particles, so that volume change in the circulation process of primary particles can be inhibited, and overpotential difference of internal and external lithium deposition is formed to force lithium metal to be deposited in the carbon cavity. The large amount of gaps in the secondary particles can provide good buffer for the expansion of the primary particles, and basically ensure the stability of the electrode.
The invention has the beneficial effects that:
1. the lithium-carrying composite framework material has stable structure and large specific surface, can effectively reduce local current density, and can realize high coulomb efficiency and long cycle life of an electrode under high current density as a host material of a lithium metal cathode.
2. The lithium-carrying composite framework material can play a role in induced deposition and multiple encapsulation on the lithium metal, the high lithium-precipitation overpotential film layer is equivalent to an artificial SEI film, the contact of elemental lithium and electrolyte is greatly reduced, the occurrence of cross-section side reaction is avoided, and the electrochemical performance, particularly the cycling stability, of the lithium metal battery is remarkably improved.
3. The lithium-carrying composite framework material has good gradient lithium affinity, rich inner cavity low-lithium-precipitation overpotential nano particles can effectively reduce lithium nucleation overpotential, and in addition, the high-lithium-precipitation overpotential of the outer film layer refuses nucleation growth of lithium, so that lithium ions are promoted to enter the cavity by the internal and external high-lithium-precipitation overpotential difference, and nucleation and uniform deposition of lithium metal in the cavity of the hollow carbon framework are realized. In addition, the skeletal structure provides rich gaps that greatly slow down the volume effect.
Drawings
Fig. 1 is an SEM image of the hollow thin-walled nanocarbon sphere prepared in example 1.
FIG. 2 is a graph showing electrochemical properties of the lithium-loaded composite scaffold material prepared in example 1 and the hollow carbon composite scaffold material prepared in comparative examples 1-2 without low-precipitation lithium overpotential nanoparticles.
Detailed Description
The following is a detailed description of the preferred embodiments of the invention and is not intended to limit the invention in any way, i.e., the invention is not intended to be limited to the embodiments described below, and modifications and alternative compounds that are conventional in the art are intended to be included within the scope of the invention as defined in the claims
Example 1
SiO with an average diameter of 500nm2The ball is prepared into 10g/L sol, stannous chloride solution with the concentration of 0.05mol/L and SiO are used2The volume ratio of the sol to the stannous chloride solution is 1:2, normal temperature activation treatment is carried out for 3 hours, suction filtration is carried out, deionized water is dispersed in 100ml of deionized water after being washed, 100ml of 0.025mol/L AgNO is added3Adding ammonia water solution dropwise to obtain silver ammonia solution, adding 125ml 0.01mol/L glucose solution dropwise at 50 deg.C, stirring for 2 hr to obtain SiO2@Ag。SiO2Cleaning @ Ag, dispersing in 50ml water, adding 0.25g dopamine and 0.25g trihydroxy aminomethane, stirring at normal temperature for 24h with pH of 8.5 to obtain SiO2@ Ag @ carbon source; filtering, mixing with water to obtain a suspension with a solid-to-liquid ratio of 40%, and spraying at 200 deg.C to obtain secondary particles stacked with hollow thin-wall carbon nanospheres. Cleaning the secondary particles, preparing 10g/L suspension, adding resorcinol monomer to prepare 1g/L suspension, and carrying out in-situ polymerization under formaldehyde reduction to obtain the precursor of the lithium-loaded composite framework material. Then heating to 400 ℃ at the speed of 5 ℃/min under high-purity argon, heating to 800 ℃ at the speed of 1 ℃/min, and roasting for 3 h. And finally stirring the mixture for 12 hours in 5mol/L NaOH solution in water bath at 70 ℃, filtering, washing and drying to obtain the lithium-carrying composite framework material (wherein the low lithium-separation overpotential nano particles are Ag with the average particle size of 25nm, and the high lithium-separation overpotential film layer is a carbon layer). In the lithium-loaded composite framework material prepared in this example, the Ag loading was 10 at.%, the N loading was 10.4 at.%, and the carbon layer thickness was 30 nm.
Comparative examples 1 to 1
The difference from example 1 is only SiO2The surface activation treatment was not performed on the spheres, and the results showed that SiO was not performed2During activation of the ball surface, SiO2The surface of the template is almost free of silver nano particles, and the inner wall of the hollow thin-wall carbon nanosphere in the finally prepared material is also almost free of silver nano particles.
Comparative examples 1 to 2
The only difference from example 1 is that SiO2The surface of the template is not compounded with silver nano particles, so that the inner wall of the hollow thin-wall carbon nanosphere in the finally prepared material is also not compounded with any silver nano particles.
Comparative examples 1 to 3
The difference from example 1 is that dopamine coating is not performed, and the result shows that Ag nanoparticles are scattered in the inner cavity of the carbon layer and are not embedded on the carbon wall. The absence of dopamine coating easily causes the incomplete synthesis of carbon spheres, and lithium metal cannot be completely encapsulated, so that the occurrence of subsequent interface side reactions is easily caused.
Comparative examples 1 to 4
The only difference from example 1 is that the secondary particles were not coated by in situ polymerization of resorcinol. The secondary particles do not include a carbon layer, and the volume effect and the interfacial side reaction are not effectively inhibited.
Comparative examples 1 to 5
The same as example 1, except that the secondary granulation was not performed by spray drying, the nano carbon spheres were in a monodisperse state.
Comparative examples 1 to 6
The difference from example 1 was only that Ag nanoparticles were replaced with Cu nanoparticles, and the result showed that little lithium metal was deposited in the nanocarbon spheres.
Comparative examples 1 to 7
The only difference from example 1 is that the encapsulation film layer of the secondary particles is a thin film plating layer of Au, and the results show that lithium metal tends to be deposited on the outer side of the secondary particles, and there is almost no lithium metal in the carbon spheres.
The materials prepared in example 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 PVDF and acetylene black, respectively, in a mass ratio of 8:1:1, NMP was added to the mixture to form a slurry, the slurry was uniformly coated on a copper foil, the slurry was dried to form a working electrode, a lithium metal sheet was used as a counter electrode, and LiNO LiFSI/DOL DME (volume ratio of 1:1) containing 2 wt% of LiNO was used as a working electrode3And assembling a button half cell for the electrolyte, and performing charge-discharge cycle test after the cell is activated. At 3mA/cm2The current density and the electric quantity of (1 mAh/cm)2The charge and discharge cycle test was performed, and the test results are shown in table 1 below:
TABLE 1 results of electrochemical Properties of materials prepared in example 1, comparative examples 1-2, comparative examples 1-3, comparative examples 1-4, comparative examples 1-5, comparative examples 1-6 and comparative examples 1-7
Figure BDA0003383268480000111
Example 2
SiO with an average diameter of 500nm2The ball is prepared into 10g/L sol, stannous chloride solution with the concentration of 0.05mol/L and SiO are used2The volume ratio of the sol to stannous chloride solution is 1:2, normal temperature activation treatment is carried out for 3 hours, suction filtration is carried out, deionized water is dispersed in 100ml of deionized water after being washed, and Zn (NO) with the concentration of 0.1mol/L is added into the activated template3)2Adding polyethylene glycol solution, adding 0.0001mol/L KOH solution, stirring for 2h to obtain ZnO nanoparticles, adding 0.5g dopamine and 0.5g trihydroxy aminomethane, adjusting pH to 8.5, stirring at room temperature for 24h to obtain the SiO2@ ZnO @ carbon source; filtering, mixing with water to obtain a suspension with a solid-to-liquid ratio of 40%, and spraying at 200 deg.C to obtain secondary particles stacked with hollow thin-wall carbon nanospheres. Cleaning the secondary particles, preparing 10g/L suspension, adding resorcinol monomer to prepare 1g/L suspension, and carrying out in-situ polymerization under formaldehyde reduction to obtain the precursor of the lithium-loaded composite framework material. Then heating to 400 ℃ at the speed of 5 ℃/min under high-purity argon, heating to 800 ℃ at the speed of 1 ℃/min, and roasting for 3 h. And finally stirring the mixture for 12 hours in 5mol/L NaOH solution in water bath at 70 ℃, filtering, washing and drying to obtain the lithium-carrying composite framework material (wherein the low-lithium-separation overpotential nano particles are ZnO with the average particle size of 30nm, and the high-lithium-separation overpotential film layer is a carbon layer). In the lithium-loaded composite framework material prepared in this example, the loading amounts of ZnO and N were 15 at.%, 12 at.%, respectively, and the carbon layer thickness was 40 nm.
Comparative example 2-1
The difference from example 2 is only that no ZnO nanoparticles doping was performed, and the results show that the inner cavity surface of the synthesized material does not have any ZnO particles.
Comparative examples 2 to 2
The only difference from example 2 is that spray drying and secondary granulation were not performed.
Comparative examples 2 to 3
The difference from example 2 is only that coating by in situ polymerization of resorcinol is not performed.
The materials prepared in example 2, comparative example 2-1, comparative example 2-2 and comparative example 2-3 were mixed with PVDF and acetylene black as binders, respectively, in a mass ratio of 8:1:1, NMP was added to the mixture to prepare a slurry, the slurry was uniformly coated on a copper foil, the slurry was dried to obtain a working electrode, a lithium metal sheet was used as a counter electrode, and LiNO was contained in an amount of 2 wt% in a volume ratio of 1MLiTFSI/DOL: DME (1: 1)3And assembling a button half cell for the electrolyte, and performing charge-discharge cycle test after the cell is activated. At 3mA/cm2The current density and the electric quantity of (1 mAh/cm)2The charge-discharge cycle test was performed, and the test results are shown in table 2 below:
TABLE 2 results of electrochemical properties of the materials prepared in example 2, comparative example 2-1, comparative example 2-2 and comparative example 2-3
Figure BDA0003383268480000121
Example 3
SiO with an average diameter of 500nm2The ball is prepared into 10g/L sol, stannous chloride solution with the concentration of 0.05mol/L and SiO are used2The volume ratio of the sol to stannous chloride solution is 1:2, normal temperature activation treatment is carried out for 3 hours, suction filtration is carried out, deionized water is dispersed in 100ml of deionized water after being washed, and the activated template is added into Cu (NO) with the concentration of 0.1mol/L3)2Then adding aqueous solution, then adding formaldehyde solution, stirring for 2h to obtain SiO2@ Cu, at H2/N2Plasma is carried out for 2h at 450 ℃ under mixed atmosphere to obtain SiO2@CuxN, adding 0.5g of dopamine and 0.5g of trihydroxy aminomethane, stirring at normal temperature for 24 hours to obtain the SiO2@CuxN @ carbon source; filtering, mixing with water to obtain a suspension with a solid-to-liquid ratio of 40%, and spraying at 200 deg.C to obtain secondary particles stacked with hollow thin-wall carbon nanospheres. Cleaning the secondary particles, preparing 10g/L suspension, adding resorcinol monomer to prepare 1g/L suspension, and carrying out in-situ polymerization under formaldehyde reduction to obtain the precursor of the lithium-loaded composite framework material. Then heating to 400 ℃ at a speed of 5 ℃/min under high-purity argon, heating to 800 ℃ at a speed of 1 ℃/min, and roasting 3h. Finally stirring the mixture for 12 hours in 5mol/L NaOH solution in water bath at 70 ℃, filtering, washing and drying to obtain the lithium-loaded composite framework material (wherein the low-precipitation lithium overpotential nano particles are Cu with the average particle size of 35 nm)xAnd N, the high lithium-extraction overpotential film layer is a carbon layer). In the lithium-carrying composite framework material prepared in this example, CuxThe N loading was 18 at.%, the N loading was 11 at.%, respectively, and the carbon layer thickness was 45 nm.
Comparative example 3-1
The only difference from example 2 is that Cu was not usedxN nano-particle doping, and the result shows that the inner cavity surface of the synthesized material does not contain any CuxAnd N particles.
Comparative examples 3 to 2
The only difference from example 2 is that spray drying and secondary granulation were not performed.
Comparative examples 3 to 3
The difference from example 2 is only that coating by in situ polymerization of resorcinol is not performed.
The materials prepared in example 3, comparative example 3-1, comparative example 3-2 and comparative example 3-3 were mixed with PVDF and acetylene black as binders, respectively, in a mass ratio of 8:1:1, NMP was added to the mixture to prepare a slurry, the slurry was uniformly coated on a copper foil, the slurry was dried to obtain a working electrode, a lithium metal sheet was used as a counter electrode, and LiNO was contained in an amount of 2 wt% in a volume ratio of 1MLiTFSI/DOL: DME (1: 1)3And assembling a button half cell for the electrolyte, and performing charge-discharge cycle test after the cell is activated. At 3mA/cm2The current density and the electric quantity of (1 mAh/cm)2The charge-discharge cycle test was performed, and the test results are shown in table 3 below:
TABLE 3 results of electrochemical Properties of the materials obtained in example 3, comparative example 3-1, comparative example 3-2 and comparative example 3-3
Figure BDA0003383268480000141
Example 4
SiO with an average diameter of 500nm2The ball is prepared into 10g/L sol, stannous chloride solution with the concentration of 0.05mol/L and SiO are used2Sol and stannous chloride solutionThe volume ratio of the template to the template is 1:2, the activation treatment is carried out for 3 hours at normal temperature, the filtration is carried out, deionized water is dispersed in 100ml of deionized water after being washed, and the activated template is added into Ni (NO) with the concentration of 0.1mol/L3)2Then adding aqueous solution, then adding formaldehyde solution, stirring for 2h to obtain SiO2@ Ni, drying, and decomposing and phosphorizing for 2h by taking sodium hypophosphite as a phosphorus source at 350 ℃ to obtain SiO2@Ni2P, adding 0.5g of dopamine and 0.5g of trihydroxy aminomethane into the mixture, stirring the mixture for 24 hours at normal temperature to obtain the SiO, wherein the pH value is 8.52@Ni2P @ carbon source; filtering, mixing with water to obtain a suspension with a solid-to-liquid ratio of 40%, and spraying at 200 deg.C to obtain secondary particles stacked with hollow thin-wall carbon nanospheres. Cleaning the secondary particles, preparing 10g/L suspension, adding resorcinol monomer to prepare 1g/L suspension, and carrying out in-situ polymerization under formaldehyde reduction to obtain the precursor of the lithium-loaded composite framework material. Then heating to 400 ℃ at the speed of 5 ℃/min under high-purity argon, heating to 800 ℃ at the speed of 1 ℃/min, and roasting for 3 h. Finally stirring the mixture for 12 hours in 5mol/L NaOH solution in water bath at 70 ℃, filtering, washing and drying to obtain the lithium-loaded composite framework material (wherein the low-precipitation lithium overpotential nano particles are Ni with the average particle size of 33 nm)2P, the high lithium deposition overpotential film layer is a carbon layer). In the lithium-carrying composite skeleton material prepared in this example, Ni2The P loading was 19 at.%, the N loading was 12 at.%, respectively, and the carbon layer thickness was 34 nm.
Comparative example 4-1
The only difference from example 2 is that Ni is not added2P nano-particle doping, and the result shows that the inner cavity surface of the synthesized material does not contain any Ni2P particles.
Comparative examples 4 to 2
The only difference from example 2 is that spray drying and secondary granulation were not performed.
Comparative examples 4 to 3
The difference from example 2 is only that coating by in situ polymerization of resorcinol is not performed.
The materials prepared in example 4, comparative example 4-1, comparative example 4-2 and comparative example 4-3 are respectively mixed with PVDF and acetylene black as binders according to the mass ratio of 8:1:1, NMP is added for slurrying, and then the materials are uniformly coatedOn a copper foil, dried to serve as a working electrode, a metallic lithium sheet as a counter electrode, and LiNO containing 2 wt% of 1MLiTFSI/DOL: DME (volume ratio of 1:1)3And assembling a button half cell for the electrolyte, and performing charge-discharge cycle test after the cell is activated. At 3mA/cm2The current density and the electric quantity of (1 mAh/cm)2The charge-discharge cycle test was performed, and the test results are shown in table 4 below:
TABLE 4 results of electrochemical properties of the materials prepared in example 4, comparative example 4-1, comparative example 4-2 and comparative example 4-3
Figure BDA0003383268480000151
Example 5
SiO with an average diameter of 500nm2The ball is prepared into 10g/L sol, stannous chloride solution with the concentration of 0.05mol/L and SiO are used2The volume ratio of the sol to stannous chloride solution is 1:2, normal temperature activation treatment is carried out for 3 hours, suction filtration is carried out, deionized water is dispersed in 100ml of deionized water after being washed, and the activated template is added into Cu (NO) with the concentration of 0.1mol/L3)2Then adding aqueous solution, then adding formaldehyde solution, stirring for 2h to obtain SiO2@ Cu, further treating heel Na in 0.005mol/L NaOH aqueous solution for 10min2S solution reacts to obtain SiO2@Cu2S, adding 0.5g of dopamine and 0.5g of trihydroxy aminomethane into the mixture, stirring the mixture for 24 hours at normal temperature to obtain the SiO2@Cu2S @ carbon source; filtering, mixing with water to obtain a suspension with a solid-to-liquid ratio of 40%, and spraying at 200 deg.C to obtain secondary particles stacked with hollow thin-wall carbon nanospheres. Cleaning the secondary particles, preparing 10g/L suspension, adding resorcinol monomer to prepare 1g/L suspension, and carrying out in-situ polymerization under formaldehyde reduction to obtain the precursor of the lithium-loaded composite framework material. Then heating to 400 ℃ at the speed of 5 ℃/min under high-purity argon, heating to 800 ℃ at the speed of 1 ℃/min, and roasting for 3 h. Finally stirring the mixture for 12 hours in 5mol/L NaOH solution in water bath at 70 ℃, filtering, washing and drying to obtain the lithium-loaded composite skeleton material (wherein the low-lithium-separation overpotential nano particles are C with the average particle size of 25 nm)u2And S, the high lithium extraction overpotential film layer is a carbon layer). In the lithium-carrying composite framework material prepared in this example, Cu2The S loading was 15 at.%, the N loading was 10 at.%, respectively, and the carbon layer thickness was 40 nm.
Comparative example 5-1
The only difference from example 5 is that Cu was not used2S nano-particle doping, and the result shows that the surface of the inner cavity of the synthesized material does not contain any Cu2And (4) S particles.
Comparative examples 5 to 2
The only difference from example 5 is that spray drying and secondary granulation were not performed.
Comparative examples 5 to 3
The difference from example 5 is only that coating by in situ polymerization of resorcinol is not performed.
The materials prepared in example 5, comparative example 5-1, comparative example 5-2 and comparative example 5-3 were mixed with PVDF and acetylene black as binders, respectively, in a mass ratio of 8:1:1, NMP was added to the mixture to prepare a slurry, the slurry was uniformly coated on a copper foil, the slurry was dried to obtain a working electrode, a lithium metal sheet was used as a counter electrode, and LiNO was contained in an amount of 2 wt% in a volume ratio of 1MLiTFSI/DOL: DME (1: 1)3And assembling a button half cell for the electrolyte, and performing charge-discharge cycle test after the cell is activated. At 3mA/cm2The current density and the electric quantity of (1 mAh/cm)2The charge-discharge cycle test was performed, and the test results are shown in table 5 below:
TABLE 5 results of electrochemical Properties of the materials obtained in example 5, comparative example 5-1, comparative example 5-2 and comparative example 5-3
Figure BDA0003383268480000161
Example 6
The lithium-loaded composite framework material prepared in example 1 (sample of example 1, wherein the low-lithium-evolution overpotential nanoparticles are Ag, and the high-lithium-evolution overpotential film layer is a single-layer carbon layer) is continuously compounded with a zinc polyacrylate film layer:
adding 0.2g of the sample in the embodiment 1 into 100ml of zinc acetate solution with the concentration of 0.1g/L and 4g/L respectively, violently stirring and dispersing, slowly dropwise adding polyacrylic acid solution with the concentration of 0.1g/L and 4g/L respectively, controlling the mass ratio of the zinc acetate to the polyacrylic acid to be 183:144, performing suction filtration and drying after reaction and precipitation, and preparing the lithium-carrying composite framework material (wherein the high-precipitation lithium overpotential film layer is a double-layer structure of a carbon layer and a zinc polyacrylate film layer). The results show that the zinc polyacrylate film layer of the composite framework material synthesized by the zinc acetate and the polyacrylic acid solution with the concentrations of 0.1g/L and 4g/L is uniform and compact, and the thicknesses of the zinc acetate and the polyacrylic acid solution are respectively 20nm and 50 nm.
Example 7
The difference from example 6 is that, without secondary carbon coating, the polypropylene zinc is directly coated on the surface of the stacked secondary particles, and the polypropylene layer is uniform, continuous and compact.
The materials prepared in example 6 and example 7 were mixed with binders PVDF and acetylene black at a mass ratio of 8:1:1, respectively, NMP was added to the mixture to make a slurry, the slurry was uniformly coated on a copper foil, the dried slurry was used as a working electrode, a metal lithium sheet was used as a counter electrode, and 1M LiTFSI/DOL: DME (volume ratio of 1:1) containing 2 wt% of LiNO3And assembling a button half cell for the electrolyte, and performing charge-discharge cycle test after the cell is activated. At 3mA/cm2The current density and the electric quantity of (1 mAh/cm)2The charge-discharge cycle test was performed, and the test results are shown in table 6 below:
table 6 electrochemical performance results for the materials prepared in example 6 and example 7
Figure BDA0003383268480000171
Example 8
The lithium-loaded composite framework material prepared in example 1 (sample of example 1, wherein the low-precipitation lithium overpotential nanoparticles are Ag, and the high-precipitation lithium overpotential film layer is a single-layer carbon layer) is continuously compounded with a CMC-Li film layer:
and acidifying CMC-Na by using an 8% HCl ethanol solution for 3 hours, filtering, washing and drying, then replacing by using a 10% LiOH solution for 5 hours and 10 hours respectively, filtering, washing and drying. The degree of substitution of CMC-Li was 0.66, 0.77. CMC-Li with a mass fraction of 5% and a mass fraction of 30% of the sample of example 1 was mixed with the sample of example 1 to prepare a homogeneous slurry, which was dispersed in water and sprayed out by spray drying with a droplet-discharging speed of 5 ml/min. The coating thickness of the CMC-Li can be controlled to be 100 nm. Preparing a lithium-loaded composite framework material (wherein the high lithium-separation overpotential film layer is a double-layer structure of a carbon layer and a CMC-Li film layer).
Table 7 electrochemical performance results for the material prepared in example 8
Figure BDA0003383268480000181
At different degrees of substitution, half-cells were assembled at 1mAcm under test conditions-2,1mAh cm-2Has better cycle life and high coulombic efficiency.
Example 9
The lithium-loaded composite framework material prepared in example 1 (wherein the low-lithium-evolution overpotential nanoparticles are Ag, and the high-lithium-evolution overpotential film layer is a single-layer carbon layer) is continuously compounded with solid electrolyte lithium aluminum germanium phosphate Li1.5Al0.5Ge1.5(PO4)3Film layer:
solid electrolyte lithium aluminum germanium phosphate Li1.5Al0.5Ge1.5(PO4)3(LAGP) particle size 200nm and coating thickness 20 μm; mixing Lithium Aluminum Germanium Phosphate (LAGP) and polyvinylidene fluoride (PVDF) according to a mass ratio of 80:20, adding the mixture into a N-methyl pyrrolidone (NMP) solution, grinding and stirring to obtain uniform slurry, coating the uniform slurry on the surface of a pole piece of a sample in example 1, drying the surface of the pole piece in a drying oven at 60 ℃ for 8 hours to serve as a working electrode, taking a metal lithium piece as a counter electrode, and taking 1M LiTFSI/DOL: DME (volume ratio of 1:1) containing 5 wt.% LiNO3And assembling the button cell for the electrolyte, and performing charge-discharge cycle test after the cell is activated. At 3mA/cm2The current density and the electric quantity of (1 mAh/cm)2And carrying out charge-discharge cycle test.
Table 8 electrochemical performance results for the material prepared in example 9
Figure BDA0003383268480000182
Example 10
The lithium-loaded composite framework material prepared in example 1 (sample of example 1, in which the low-precipitation lithium overpotential nanoparticles are Ag and the high-precipitation lithium overpotential film layer is a single-layer carbon layer) was continuously compounded with Al2O3Film layer:
mixing 0.2g of the sample in the example 1 with PVDF and acetylene black as binders according to the mass ratio of 8:1:1, adding NMP to prepare slurry, uniformly coating the slurry on a copper foil, drying the slurry in a hollow mode, placing the dried slurry in an atomic deposition system (Savannah S100ALD system), and placing the dried slurry in a mixed electrolyte of trimethylaluminum and deionized water at the temperature of 150 ℃ for a pulse time of 0.015-15S-40S-0.015-15S-40S to prepare a lithium-loaded composite framework material (wherein a high-precipitation lithium overpotential film layer is a carbon layer and Al2O3A bilayer structure of the film layer). The results show that the vein 110s synthesized composite skeleton material, its Al2O3The thickness of the film layer is 20nm, and the film layer is uniform and compact.
Example 10-1
The only difference from example 10 is that, in the absence of secondary carbon coating, Al2O3The film layer is directly coated on the surface of the stacked secondary particles, Al2O3The film layer is uniform, continuous and compact.
The electrode sheets obtained in example 10 and example 10-1 were dried and used as working electrodes, lithium metal sheets as counter electrodes, and LiNO 2 wt% in 1M LiTFSI/DOL DME (volume ratio 1:1)3And assembling a button half cell for the electrolyte, and performing charge-discharge cycle test after the cell is activated. At 3mA/cm2The current density and the electric quantity of (1 mAh/cm)2The charge-discharge cycle test was performed, and the test results are shown in table 9 below:
TABLE 9 results of electrochemical properties of the materials obtained in example 10 and example 10-1
Figure BDA0003383268480000191
Example 11
The lithium-loaded composite framework material prepared in example 1 (sample of example 1, wherein the low-lithium-evolution overpotential nanoparticles are Ag, and the high-lithium-evolution overpotential film layer is a single-layer carbon layer) is continuously compounded with an ion/electron mixed conductor layer:
0.2g of the sample of example 1 was mixed with PVDF and acetylene black as binders in a mass ratio of 8:1:1, NMP was added to the mixture to form a slurry, the slurry was uniformly coated on a copper foil, the copper foil was dried in the air and placed in an atomic deposition system (Savannah S100ALD system) in a silicon tetrachloride electrolyte at a temperature of 120 ℃ for a pulse time of 1S-15S-30S-1S-15S-30S, the electrode was cleaned with ethanol and then used as a working electrode, a lithium metal sheet was used as a counter electrode, and 1M LiTFSI/DOL: DME (volume ratio of 1:1) containing 2 wt% LiNO3Assembling a button-type half cell for electrolyte, activating at a voltage of 0-1V, and embedding lithium to obtain a lithium-loaded composite framework material (wherein the high lithium-separation overpotential film layer is a carbon layer and Li)22Si5A bilayer structure of a mixed ion/electron conductor layer). The results show that the composite framework material synthesized by the pulse 92s, Li thereof22Si5The thickness of the film layer is 25nm, and the film layer is uniform and compact.
Example 11-1
The only difference from example 11 is that, without secondary carbon coating, Li22Si5The film layer is directly coated on the surface of the stacked secondary particles, Li22Si5The film layer is uniform, continuous and compact.
The electrode sheets obtained in example 11 and example 11-1 were dried and used as working electrodes, lithium metal sheets as counter electrodes, and LiNO 2 wt% in 1M LiTFSI/DOL DME (volume ratio 1:1)3And assembling a button half cell for the electrolyte, and performing charge-discharge cycle test after the cell is activated. At 3mA/cm2The current density and the electric quantity of (1 mAh/cm)2The charge-discharge cycle test was performed, and the test results are shown in table 10 below:
TABLE 10 results of electrochemical Properties of materials obtained in example 11 and example 11-1
Figure BDA0003383268480000201
Example 12
Mixing the lithium-loaded composite framework material prepared in example 1, polyvinylidene fluoride (PVDF) and conductive carbon according to the mass ratio of 8:1:1, adding the mixture into a N-methyl pyrrolidone (NMP) solution, grinding and stirring to obtain uniform slurry, coating the uniform slurry on a copper foil, drying the uniform slurry in a drying oven at 60 ℃ for 8 hours to obtain a working electrode, taking a metal lithium sheet as a counter electrode, and taking 1.0M LiPF6And in 89 vol% of 1:1w/wEC: DEC +10 vol% of FEC +1 vol% of VC as electrolyte for button cell assembly, discharging the cell after 0-1V pretreatment for 5 circles until 0V fully embeds lithium, disassembling the cell to take down a pole piece, matching with a lithium iron phosphate positive pole material, assembling a full cell, and simultaneously, performing corresponding charge-discharge cycle test by taking the non-pretreated lithium-carrying composite framework material as a comparison sample. Charge and discharge cycle tests were performed at 1C.
Table 11 electrochemical performance results for the material prepared in example 12
Figure BDA0003383268480000202
Example 13
Mixing the lithium-loaded composite framework material prepared in example 1, polyvinylidene fluoride (PVDF) and conductive carbon according to the mass ratio of 8:1:1, adding the mixture into a N-methyl pyrrolidone (NMP) solution, grinding and stirring to obtain uniform slurry, coating the uniform slurry on a copper foil, drying the uniform slurry in a drying oven at 60 ℃ for 8 hours to obtain a working electrode, taking a metal lithium sheet as a counter electrode, and taking 1.0M LiPF6in 89 vol% 1:1w/wEC: DEC +10 vol% FEC +1 vol% VC. Assembling button cell with electrolyte, activating the cell at 0-1V for 5 circles, discharging, and respectively depositing 5 and 10mAh/cm2Lithium metal. And (3) disassembling the battery, taking down the pole piece, matching with the lithium iron phosphate positive pole material, assembling the full battery, and simultaneously, carrying out corresponding charge-discharge cycle test by taking the pure metal lithium piece as a reference sample. Charge and discharge cycle tests were performed at 1C.
Table 12 electrochemical performance results for the material prepared in example 13
Figure BDA0003383268480000211

Claims (10)

1. A lithium-carrying composite framework material is characterized in that: the membrane is a thin-wall carbon nanosphere packaging structure with a plurality of hollow thin-wall carbon nanospheres packaged inside, low-lithium-evolution overpotential nanoparticles are compounded on the inner walls of the hollow thin-wall carbon nanospheres, the membrane is a high-lithium-evolution overpotential membrane layer, the membrane layer is a single layer or multiple layers, and the membrane layer is selected from a carbon layer, a polymer membrane layer, a solid electrolyte membrane layer, an oxide membrane layer or an ion/electron mixed conductor membrane layer;
the low lithium extraction overpotential nanoparticles are defined as having a reaction potential with lithium greater than 0V (Vs. Li/Li)+) The simple substance or compound of (a);
the high lithium extraction overpotential film layer is defined to make the electrodeposition potential of lithium on the surface of the film layer less than 0V (Vs+) The film layer of (2).
2. The lithium-bearing composite scaffolding material of claim 1, wherein: the hollow thin-wall carbon nanospheres contain lithium-philic functional groups, and the lithium-philic functional groups are one or a combination of more of nitrogen-containing functional groups, oxygen-containing functional groups, fluorine-containing functional groups and sulfur-containing functional groups;
the hollow thin-wall carbon nanospheres are at least one of spherical, rugby-ball, disc-shaped, persimmon cake-shaped and red blood cell-shaped; the hollow thin-wall carbon nanospheres have the particle size of 10-990 nm and the number of 1 or more;
the thickness of the shell of the hollow thin-wall carbon nanosphere and the thickness of the high lithium extraction overpotential film layer are both 0.1-100 nm.
3. The lithium-bearing composite scaffolding material of claim 1, wherein: the low-lithium-evolution overpotential nano particles are lithium-intercalatable compounds or simple substances capable of being alloyed with lithium;
the lithium embeddable compound is Ag2O,Co3O4,NiO,ZnO,CuxO,MgO,Ag2S,Cu2S,NixN,CuxN,Ni2P,Cu3P,CoP,ZnP,SnP,FePO4,LixMn2O4,LixCoO2One or more combinations of;
the simple substance is one or a combination of more of graphite, boron, silver, gold, platinum, zinc, magnesium, cobalt, tin, germanium, silicon, aluminum, indium and calcium.
4. The lithium-bearing composite scaffolding material according to claim 3, wherein: the low-lithium-evolution overpotential nano particles and the inner wall of the hollow thin-wall carbon nanosphere are compounded in a decoration, embedding or penetrating mode.
5. The lithium-bearing composite scaffolding material of claim 1, wherein: the carbon layer is one or the combination of more of a graphitized carbon layer and an amorphous carbon layer;
the polymer is 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 one or the combination of more of alumina, titanium oxide, zirconium oxide and germanium oxide;
the solid electrolyte is lithium aluminum germanium phosphate (Li)1.5Al0.5Ge1.5(PO4)3) Garnet type Li7La3Zr2O12、Li1.4Al0.4Ti1.6(PO4)3One or more of lithium niobate, lithium zirconate, lithium phosphide, lithium nitride, lithium fluoride and lithium titanate;
the mixed ion/electron conductor is LiC6、Li22Si5、Li9Al4、Li15Ge4、Li22Sn5、CuLixOne or more of (a) or (b).
6. The method for preparing the lithium-carrying composite framework material according to any one of claims 1 to 5, comprising the following steps:
the method comprises the following steps: template activation
Placing the template in a solution of a surfactant for surface activation, and separating to obtain a surface activated template;
the template is at least one of simple substance silicon, silicon dioxide, titanium dioxide, zinc oxide, magnesium oxide, calcium oxide and polyacrylamide;
the surface active agent is sodium hydroxide, stannous chloride and PbCl2At least one of mercaptopropyl-trimethoxysilane;
step two: template surface composite low-precipitation lithium overpotential nano-particles
Compounding the low-lithium-extraction overpotential nanoparticles on the surface of the surface-activated template to obtain surface-activated template @ low-lithium-extraction overpotential nanoparticles;
step three: carbon coating
Carrying out surface coating on the surface-activated template @ low-analysis lithium overpotential nano particle with a precursor carbon source to obtain the surface-activated template @ low-analysis lithium overpotential nano particle @ carbon source;
step four: roasting
Roasting the surface-activated template @ low-lithium-extraction overpotential nano particle @ carbon source in a protective atmosphere to obtain a surface-activated template @ low-lithium-extraction overpotential nano particle @ C;
step five: stripper plate
Placing the surface-activated template @ low-lithium-extraction overpotential nano particle @ C in an etchant solution for template etching, and performing template stripping treatment to obtain hollow thin-wall carbon nanospheres with low-lithium-extraction overpotential nano particles compounded on the inner walls;
step six: hollow thin-wall nano carbon ball packaged by high-precipitation lithium overpotential film layer
Stacking the hollow thin-wall carbon nanospheres into secondary particles, and compounding the high-lithium-separation overpotential film layer on the surface of the secondary particles to encapsulate the secondary particles to obtain single-layer high-lithium-separation overpotential film layer encapsulated hollow thin-wall carbon nanospheres; or the high lithium extraction overpotential film layer is repeatedly compounded on the single-layer high lithium extraction overpotential film layer to form the hollow thin-wall carbon nanosphere packaged by the multiple-layer high lithium extraction overpotential film layers.
7. The method of claim 6, wherein: in the third step, the carbon source is at least one of dopamine hydrochloride, resorcinol, glucose, sucrose, polyvinylpyrrolidone and tannic acid;
in the fourth step, the protective atmosphere is Ar and N2Or He atmosphere; the temperature rise rate in the roasting process is 1-10 ℃/min, the roasting temperature is 500-950 ℃, and the roasting time is 1-8 h;
in the fifth step, the etching agent is an acidic etching agent, an alkaline etching agent or an organic etching agent; the acidic etching agent is HF and HNO3、H2SO4At least one of HCl; the alkaline etchant is NaOH, KOH, LiOH, Ca (OH)2At least one of; the organic etchant is ammonium bifluoride and CF4、C4F8At least one of; the etching temperature of the template etching is 30-80 ℃, and the etching time is 6-24 h.
8. Use of the lithium-loaded composite scaffold material according to any one of claims 1 to 5 or the lithium-loaded composite scaffold material prepared by the preparation method according to any one of claims 6 to 7, wherein: the lithium-carrying composite framework material is pretreated to be used as a lithium-free negative electrode material and is used for a lithium ion primary or secondary battery;
or the lithium metal loaded lithium metal is used as a lithium negative electrode material or a lithium supplement material for a lithium metal primary or secondary battery.
9. Use according to claim 8, characterized in that: the pretreatment is to remove functional groups which are easy to cause lithium loss on the surface of the lithium-carrying composite framework material by a physical or chemical method, and the method is selected from one of an electrochemical method, a molten lithium infiltration method and a molten lithium atomization activation method; the molten lithium atomization activation method is to spray and atomize molten liquid lithium and then rapidly react with the lithium-carrying composite framework material in a fluidized bed so as to remove functional groups which are easy to cause lithium loss on the surface of the lithium-carrying composite framework material.
10. Use according to claim 8, characterized in that: the loaded metal lithium is formed by compounding lithium metal into the internal space of the lithium-loaded composite framework material by a physical or chemical method, and is 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 inject and atomize molten liquid lithium and then to circularly react with the lithium-carrying composite framework material in a fluidized bed so as to compound lithium metal into the inner space of the lithium-carrying composite framework material.
CN202111442827.4A 2021-11-30 2021-11-30 Lithium-loaded composite framework material and preparation method and application thereof Pending CN114142013A (en)

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