CN115117303A - Lithium metal negative electrode, preparation method thereof and lithium secondary battery - Google Patents

Lithium metal negative electrode, preparation method thereof and lithium secondary battery Download PDF

Info

Publication number
CN115117303A
CN115117303A CN202110290078.1A CN202110290078A CN115117303A CN 115117303 A CN115117303 A CN 115117303A CN 202110290078 A CN202110290078 A CN 202110290078A CN 115117303 A CN115117303 A CN 115117303A
Authority
CN
China
Prior art keywords
lithium metal
dimensional conductive
lithium
negative electrode
conductive framework
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202110290078.1A
Other languages
Chinese (zh)
Inventor
杨成林
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Evergrande New Energy Technology Shenzhen Co Ltd
Original Assignee
Evergrande New Energy Technology Shenzhen Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Evergrande New Energy Technology Shenzhen Co Ltd filed Critical Evergrande New Energy Technology Shenzhen Co Ltd
Priority to CN202110290078.1A priority Critical patent/CN115117303A/en
Publication of CN115117303A publication Critical patent/CN115117303A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0416—Methods of deposition of the material involving impregnation with a solution, dispersion, paste or dry powder
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/663—Selection of materials containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Composite Materials (AREA)
  • Dispersion Chemistry (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention belongs to the technical field of negative electrode materials, and particularly relates to a lithium metal negative electrode, a preparation method thereof and a lithium secondary battery. In the lithium metal cathode, the surface of a three-dimensional conductive framework is modified with amino (-NH) 2 ) Due to the strong amino groupThe polarity has stronger adsorption effect on lithium ions, thereby promoting the lithium metal to be uniformly distributed along the surface of the three-dimensional conductive framework in the charging and discharging process, avoiding the lithium metal from being locally aggregated to form lithium dendrite on the three-dimensional conductive framework and ensuring that the lithium metal cathode has good cycle performance. Meanwhile, the wettability of the three-dimensional conductive framework with the amino modified on the surface to the lithium metal is enhanced, so that the contact area of the lithium metal and the three-dimensional conductive framework is larger, the electron transfer resistance is reduced, and the electrochemical performance of the lithium metal cathode is improved.

Description

Lithium metal negative electrode, preparation method thereof and lithium secondary battery
Technical Field
The invention belongs to the technical field of cathode materials, and particularly relates to a lithium metal cathode, a preparation method thereof and a lithium secondary battery.
Background
The lithium metal negative electrode is widely concerned due to the advantages of high capacity and low potential, and the main difficulty of limiting the industrialization application of the lithium metal negative electrode at present is the safety problem caused by the growth of lithium dendrite.
One of the existing schemes for relieving the growth of lithium dendrites in a lithium metal negative electrode is to deposit lithium metal on the surface of a three-dimensional conductive framework, so that the growth of the lithium dendrites is inhibited, and the volume expansion in the charging and discharging process can be relieved. However, the materials of the three-dimensional conductive framework commonly used at present are all carbon materials, and have the problem of poor wettability to lithium metal, so that the deposition uniformity of the lithium metal is poor, and the poor contact between the lithium metal and the carbon materials can cause the loss of contact between the lithium metal and a current collector, and the blockage of an electron path and the formation of dead lithium. Therefore, if the wettability of the lithium metal to the three-dimensional conductive skeleton can be improved, the electrochemical performance of the lithium metal negative electrode can be improved.
Disclosure of Invention
The invention aims to provide a lithium metal negative electrode, a preparation method thereof and a lithium secondary battery, and aims to solve the technical problem of poor wettability between lithium metal and a three-dimensional conductive framework in the conventional lithium metal negative electrode.
In order to achieve the above object, in one aspect, the present invention provides a lithium metal negative electrode, which includes a three-dimensional conductive skeleton and lithium metal, wherein the lithium metal is loaded on the three-dimensional conductive skeleton, and an amino group is modified on the surface of the three-dimensional conductive skeleton.
In the lithium metal negative electrode provided by the invention, amino (-NH) is modified on the surface of the three-dimensional conductive framework 2 ) The amino has stronger polarity and has stronger adsorption effect on lithium ions, so that the lithium metal is promoted to be uniformly distributed along the surface of the three-dimensional conductive framework in the charging and discharging process, the lithium metal is prevented from being locally aggregated to form lithium dendrites on the three-dimensional conductive framework, and the lithium metal cathode has good cycle performance. Meanwhile, the wettability of the three-dimensional conductive framework with the amino modified on the surface to the lithium metal is enhanced, so that the lithium metal is enabled to beThe contact area with the three-dimensional conductive framework is larger, the electron transfer resistance is reduced, and the electrochemical performance of the lithium metal cathode is further improved.
As a preferred technical scheme of the lithium metal cathode, the modification area of the amino accounts for 60-100% of the surface area of the three-dimensional conductive framework.
As a preferred technical scheme of the lithium metal cathode, silver oxide particles are modified on the surface of the three-dimensional conductive framework, and the modified area of the silver oxide particles accounts for 0-40% of the surface area of the three-dimensional conductive framework.
As a preferred technical scheme of the lithium metal negative electrode, the capacity of the metal lithium on the three-dimensional conductive framework is 2mAh/cm 2 -10mAh/cm 2 。
As a preferred technical solution of the lithium metal negative electrode of the present invention, the three-dimensional conductive skeleton is at least one selected from a carbon fiber film, a carbon nanotube film, and a graphene film.
As a preferable technical scheme of the lithium metal negative electrode, the thickness of the three-dimensional conductive framework is 20-100 mu m.
In another aspect of the present invention, a method for preparing a lithium metal negative electrode is provided, which includes the following steps:
providing a three-dimensional conductive framework and liquid metal lithium, wherein the surface of the three-dimensional conductive framework is modified with amino;
and infiltrating the three-dimensional conductive framework into liquid metal lithium to obtain the lithium metal cathode.
In the preparation method of the lithium metal cathode provided by the invention, the amino modified on the surface of the three-dimensional conductive framework improves the wettability to the lithium metal, so that the lithium metal can be uniformly distributed on the surface of the three-dimensional conductive framework by a simple wetting method, the lithium metal cathode with good electrochemical performance is obtained, and the preparation method has the advantages of simple steps, easiness in implementation and contribution to realizing industrial production.
As a preferable technical scheme of the preparation method of the lithium metal cathode, the method for modifying the amino group on the surface of the three-dimensional conductive framework comprises the following steps:
providing a three-dimensional conductive framework and ammonia water;
and soaking the three-dimensional conductive framework in ammonia water, and carrying out heat treatment to obtain the three-dimensional conductive framework with the surface modified with amino.
In a more preferable embodiment of the method for producing a lithium metal negative electrode according to the present invention, a silver salt is further added to the amino group-containing compound solution.
As a further preferable embodiment of the method for producing a lithium metal negative electrode of the present invention, the concentration of the aqueous ammonia is 20 wt.% to 30 wt.%.
As a further preferable embodiment of the method for producing a lithium metal negative electrode of the present invention, the concentration of the silver salt is 2mmol/L to 5 mmol/L.
As a further preferable technical scheme of the preparation method of the lithium metal cathode, the heat treatment is carried out in protective atmosphere, the temperature of the heat treatment is 300-400 ℃, and the time of the heat treatment is 10-30 min.
In a final aspect of the present invention, a lithium secondary battery is provided, which includes a positive electrode, a negative electrode, and an electrolyte disposed between the positive electrode and the negative electrode, wherein the negative electrode is the lithium metal negative electrode provided in the present invention, or the lithium metal negative electrode prepared by the method for preparing the lithium metal negative electrode provided in the present invention.
In the lithium secondary battery provided by the invention, the negative electrode is the lithium metal negative electrode provided by the invention, and the amino group is modified on the surface of the three-dimensional conductive framework of the lithium metal negative electrode so as to improve the wettability to the lithium metal, so that the lithium metal can be uniformly distributed on the surface of the three-dimensional conductive framework, lithium dendrite is avoided, the contact area can be increased, the electron transfer resistance is reduced, and the lithium metal negative electrode has good electrochemical performance. Therefore, the lithium secondary battery containing the lithium metal negative electrode also has good electrochemical performance and good application prospect.
Drawings
FIG. 1 is a schematic diagram of a three-dimensional conductive skeleton according to an embodiment of the present invention before and after amino group modification on the surface of the three-dimensional conductive skeleton;
fig. 2 is a schematic view of the effect of loading lithium metal before and after modifying an amino group on the surface of a three-dimensional conductive framework according to an embodiment of the present invention;
FIG. 3 is an electron micrograph of a lithium metal negative electrode obtained in example 1 of the present invention;
FIG. 4 is a graph showing the comparison of the cycle performance of a symmetrical battery composed of the lithium metal negative electrode obtained in example 1 of the present invention and the lithium metal negative electrode provided in comparative example 1;
fig. 5 is a graph showing the comparison of the cycle performance of the full cell composed of the lithium metal negative electrode obtained in example 1 of the present invention and the lithium metal negative electrode provided in comparative example 1.
Detailed Description
In order to make the objects, technical solutions and technical effects of the embodiments of the present invention clearer and more completely describe the technical solutions in the embodiments of the present invention, the embodiments described below are a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art without any inventive step in connection with the embodiments of the present invention shall fall within the scope of protection of the present invention. Those whose specific conditions are not specified in the examples are carried out according to conventional conditions or conditions recommended by the manufacturer; the reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
In the description of the present invention, the term "and/or" describing an association relationship of associated objects means that there may be three relationships, for example, a and/or B, may mean: a is present alone, A and B are present simultaneously, and B is present alone. Wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.
In the description of the present invention, "at least one" means one or more, and "a plurality" means two or more. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, "at least one (a), b, or c", or "at least one (a), b, and c", may each represent: a. b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple respectively.
It should be understood that the weight of the related components mentioned in the embodiments of the present invention may not only refer to the specific content of each component, but also represent the proportional relationship of the weight among the components, and therefore, it is within the scope of the disclosure that the content of the related components is scaled up or down according to the embodiments of the present invention. Specifically, the weight described in the embodiments of the present invention may be a unit of mass known in the chemical field, such as μ g, mg, g, kg, etc.
In addition, unless the context clearly uses otherwise, an expression of a word in the singular is to be understood as including the plural of the word. The terms "comprises" or "comprising" are intended to specify the presence of stated features, quantities, steps, operations, elements, portions, or combinations thereof, but are not intended to preclude the presence or addition of one or more other features, quantities, steps, operations, elements, portions, or combinations thereof.
The embodiment of the invention provides a lithium metal negative electrode which comprises a three-dimensional conductive framework and metal lithium, wherein the metal lithium is loaded on the three-dimensional conductive framework, and amino groups are modified on the surface of the three-dimensional conductive framework.
The lithium metal negative electrode provided by the embodiment of the present invention will be described in detail below with reference to fig. 1 and 2. Fig. 1 shows schematic diagrams before and after modifying an amino group on the surface of a three-dimensional conductive skeleton (a part of one of the skeletons), and it can be seen that the amino group is linked to the skeleton surface of the three-dimensional conductive skeleton through a C — N covalent bond by the modification. Fig. 2 is a schematic view showing the effect of loading lithium metal before and after the surface modification of amino groups on the three-dimensional conductive skeleton, and it can be seen that the lithium metal is easily aggregated at the intersections of the three-dimensional skeleton and forms lithium dendrites when the lithium metal is loaded on the three-dimensional conductive skeleton before the surface modification of amino groups on the three-dimensional conductive skeleton; after the surface of the three-dimensional conductive framework is modified with amino, the loaded lithium metal is uniformly distributed on the surface of the framework under the adsorption of the amino. Therefore, in the lithium metal negative electrode provided by the embodiment of the invention, the surface of the three-dimensional conductive framework is modified by amino (-NH) 2 ) Because the amino has stronger polarity and has stronger adsorption effect on lithium ions, the lithium metal is promoted to be uniformly distributed along the surface of the three-dimensional conductive framework in the charging and discharging process, the lithium metal is prevented from being locally aggregated to form lithium dendrites on the three-dimensional conductive framework, and the lithium metal is made to be negativeHas excellent cycle performance. Meanwhile, the wettability of the three-dimensional conductive framework (namely the amino modified three-dimensional conductive framework) with the amino modified on the surface to the lithium metal is enhanced, so that the contact area of the lithium metal and the three-dimensional conductive framework is larger, the electron transfer resistance is reduced, and the electrochemical performance of the lithium metal cathode is improved.
In some embodiments, in the three-dimensional conductive skeleton modified with amino groups, the amino groups are uniformly distributed on the surface of the three-dimensional conductive skeleton and completely cover the surface of the three-dimensional conductive skeleton. Through the distribution mode, the uniformity of lithium metal deposition can be further promoted, and the cycle performance of the lithium metal negative electrode is improved. In some embodiments, the modified area of the amino groups comprises 60% to 100% of the surface area of the three-dimensional conductive scaffold. If the modification area of the amino group is too small, it is difficult to sufficiently adsorb lithium ions, and the effect of suppressing lithium dendrites is not significant. Specifically, the modified area of the amino group typically, but not by way of limitation, comprises 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100% of the surface area of the three-dimensional conductive scaffold.
In some embodiments, the three-dimensional conductive framework surface is modified with silver oxide particles in addition to amino groups. At this time, the amino group and the silver oxide particles together completely cover the surface of the three-dimensional conductive skeleton. The silver oxide particles are combined with the three-dimensional conductive framework through Van der Waals force, so that the wettability of the three-dimensional conductive framework material to lithium metal can be further improved, lithium ions are deposited more uniformly in the circulation process, and the generation of lithium dendrites is inhibited. The silver oxide particles and the amino group modify the three-dimensional conductive framework together, so that the problem that the silver oxide particles are difficult to uniformly distribute on the surface of the three-dimensional conductive framework when only modified by the silver oxide particles is solved, and meanwhile, the production cost is also reduced. In some embodiments, the modified area of the silver oxide particles comprises 0-40% of the surface area of the three-dimensional conductive framework. If the modification area of the silver oxide particles is too high, not only the modification area of amino groups can be influenced, but also excessive silver oxide is easily gathered at the crossing position of the three-dimensional conductive framework, and the uniform deposition of lithium ions is not facilitated. Specifically, the modified area of the silver oxide particles typically, but not by way of limitation, comprises 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% of the surface area of the three-dimensional conductive framework.
In some embodiments, the lithium metal negative electrode has a lithium metal loading of 2mAh/cm on the three-dimensional conductive skeleton 2 -10mAh/cm 2 . If the loading capacity of the metal lithium is too low, the lithium cannot be sufficiently supplemented; if the loading of metallic lithium is too high, the energy density of the battery is affected. Specifically, a typical, but non-limiting, loading is 2mAh/cm 2 、3mAh/cm 2 、4mAh/cm 2 、5mAh/cm 2 、6mAh/cm 2 、7mAh/cm 2 、8mAh/cm 2 、9mAh/cm 2 、10mAh/cm 2 。
The three-dimensional conductive framework in the embodiment of the present invention is a conductive material having a three-dimensional network structure, and in some embodiments, the three-dimensional conductive framework is selected from at least one of a carbon fiber film, a carbon nanotube film, and a graphene film. The materials are all three-dimensional conductive carbon materials, have good conductivity, and are beneficial to improving the uniform distribution effect of lithium metal after amino modification.
Further, the thickness of the three-dimensional conductive framework is 20-100 μm. If the thickness of the three-dimensional conductive framework is too thin, the mechanical strength is low, the stability of the lithium metal negative electrode is influenced, and meanwhile, the electrode is not easy to manufacture; if the thickness of the three-dimensional conductive skeleton is too thick, the resistance of the lithium metal negative electrode is easily too high, and the electrochemical performance of the lithium metal negative electrode is further affected. In particular, typical, but not limiting, three-dimensional conductive scaffolds have thicknesses of 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm.
The lithium metal negative electrode provided by the embodiment of the invention can be prepared by the following method.
Correspondingly, the embodiment of the invention provides a preparation method of a lithium metal negative electrode, which comprises the following steps:
s1, providing a three-dimensional conductive framework and liquid metal lithium, wherein the surface of the three-dimensional conductive framework is modified with amino;
and S2, soaking the three-dimensional conductive framework in liquid metal lithium to obtain the lithium metal negative electrode.
In the preparation method of the lithium metal cathode provided by the embodiment of the invention, due to the fact that the wettability of the lithium metal is improved by the amino modified on the surface of the three-dimensional conductive framework, the lithium metal can be uniformly distributed on the surface of the three-dimensional conductive framework through a simple soaking method, the lithium metal cathode with good electrochemical performance is obtained, and the preparation method has the advantages of being simple in steps, easy to implement and beneficial to industrial production. It should be noted that, the preparation process of the lithium metal negative electrode provided in the embodiment of the present invention should be performed in a protective atmosphere, so as to avoid oxidation and other phenomena of the active lithium metal, which affect the performance of the lithium metal negative electrode, and avoid the inhibition of decomposition of the silver salt due to the presence of oxygen.
Specifically, in S1, the selection of the three-dimensional conductive skeleton and the thickness thereof are as described above, and are not described herein again. In some embodiments, the method for surface modification of amino groups on a three-dimensional conductive skeleton comprises the following steps:
s11, providing a three-dimensional conductive framework and ammonia water;
and S12, soaking the three-dimensional conductive framework in ammonia water, and performing heat treatment to obtain the three-dimensional conductive framework with the surface modified with amino.
The three-dimensional conductive skeleton modified with amino groups prepared by the method has good stability and better affinity to lithium metal, and is beneficial to promoting the uniform loading of the lithium metal.
In S11, ammonia was used in the present example to react with C in the three-dimensional conductive skeleton to generate an amino group. In some embodiments, the concentration of aqueous ammonia is 20 wt.% to 30 wt.%. If the concentration of ammonia is too low, sufficient amino groups cannot be provided, and the problem that the amino groups modified on the surface of the three-dimensional conductive skeleton are too few and are difficult to uniformly distribute is easily caused. If the concentration of ammonia is too high, an excessive amount of amino groups tend to aggregate at the crossing positions of the three-dimensional conductive skeleton, resulting in the deposition of lithium metal. Specifically, the typical, but not limiting, concentration of aqueous ammonia is 20 wt.%, 21 wt.%, 22 wt.%, 23 wt.%, 24 wt.%, 25 wt.%, 26 wt.%, 27 wt.%, 28 wt.%, 29 wt.%, 30 wt.%.
Further, a silver salt is added to the ammonia water provided by the embodiment of the invention. The silver salt is added, so that the silver oxide particles can be decomposed in the subsequent heat treatment process and are positioned on the surface of the three-dimensional conductive framework together with the amino, the wettability of the three-dimensional conductive framework material on lithium metal is further improved, the lithium ions are more uniformly deposited in the circulation process, and the generation of lithium dendrites is inhibited. In one embodiment, the preparation method is to mix and disperse the silver salt and ammonia water in the solvent to form a mixed solution containing both amino and silver salt for the subsequent reaction. Wherein the concentration of the silver salt in the mixed solution is preferably 2mmol/L-5mmol/L, and the silver salt is preferably silver nitrate. If the concentration of the silver salt is too low, sufficient silver oxide particles cannot be formed, and the silver oxide particles on the surface of the three-dimensional conductive framework are too few, so that the promotion effect of further improving the wettability of the three-dimensional conductive framework on lithium metal cannot be achieved; if the concentration of silver salt is too high, the excessive silver oxide is easily gathered at the crossing position of the three-dimensional conductive skeleton, which is not favorable for the uniform deposition of lithium ions. Specifically, typical, but non-limiting, concentrations of the silver salt are 2mmol/L, 2.5mmol/L, 3mmol/L, 3.5mmol/L, 4mmol/L, 4.5mmol/L, 5 mmol/L.
And S12, soaking the three-dimensional conductive framework in ammonia water, and performing heat treatment to connect amino groups to the framework surface of the three-dimensional conductive framework through covalent bonds.
It will be appreciated that the heat treatment process of the embodiments of the present invention should be carried out in a protective atmosphere since the presence of oxygen inhibits the decomposition of silver salts, such as silver nitrate. Protective atmospheres include, but are not limited to, inert gases such as nitrogen, argon, and the like.
In some embodiments, when the ammonia contains a silver salt, after the heat treatment, the amino group is bonded to the skeleton surface of the three-dimensional conductive skeleton by a covalent bond, and the silver salt is decomposed to produce silver oxide and is bonded to the skeleton surface of the three-dimensional conductive skeleton by van der waals force.
In some embodiments, the three-dimensional conductive framework is immersed in ammonia water and left for 3h to 10h before the heat treatment. Because some three-dimensional conductive frameworks have poor hydrophilicity, the ammonia water can fully wet the three-dimensional conductive frameworks by standing. In particular, typical but not limiting standing times are 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10 h.
In some embodiments, the temperature of the heat treatment is 300 ℃ to 400 ℃ and the time of the heat treatment is 10min to 30 min. If the temperature of the heat treatment is too low or the time is too short, the silver salt is difficult to sufficiently decompose into silver oxide; such as too high temperature or too long time for heat treatment, not only causes waste of resources, but also easily introduces excessive impurities. Specifically, typical but not limiting heat treatment temperatures are 300 deg.C, 310 deg.C, 320 deg.C, 330 deg.C, 340 deg.C, 350 deg.C, 360 deg.C, 370 deg.C, 380 deg.C, 400 deg.C; typical but non-limiting heat treatment times are 10min, 15min, 20min, 25min, 30 min.
In some embodiments, in order to improve the lithium metal loading effect of the amino-modified three-dimensional conductive skeleton, in S12, after the amino-modified three-dimensional conductive skeleton is obtained, a cleaning process and a drying process are further performed to remove residual ammonia water. The cleaning process may be performed by a conventional method in the art, and in some embodiments, the three-dimensional conductive skeleton modified with amino groups is cleaned with deionized water. The drying process may also be performed by methods conventional in the art, and in some embodiments, sufficient drying at 80 ℃ is preferred to obtain good performance of the amino-modified three-dimensional conductive backbone.
The liquid metal lithium in S1 is used to be supported on the amino-modified three-dimensional conductive skeleton in the embodiment of the present invention. In some embodiments, the metallic lithium may be optionally heated to a molten state to obtain liquid metallic lithium.
In S2, the three-dimensional conductive framework is soaked in the liquid metal lithium to load the metal lithium on the three-dimensional conductive framework, and meanwhile, the surface of the framework of the three-dimensional conductive framework is uniformly modified with amino groups, so that the affinity to the metal lithium is high, and the metal lithium can be uniformly loaded on the three-dimensional conductive framework under the adsorption action, and the lithium metal cathode is obtained. In the lithium metal negative electrode, because of uniform loading of the metal lithium, the problem that the metal lithium generates lithium dendrites because of being gathered at the positions of a cross point and the like of the three-dimensional conductive framework can be avoided, and the lithium metal negative electrode has better cycle stability. In addition, the wettability of the amino-modified three-dimensional conductive framework on the metal lithium is enhanced, so that the metal lithium and the three-dimensional conductive framework have larger contact area, the electron transfer resistance is reduced, and the electrochemical performance of the obtained lithium metal cathode is improved.
In order to make the above implementation details and operations of the present invention clearly understood by those skilled in the art, and to make the progress of the lithium metal negative electrode, the method for manufacturing the same, and the lithium secondary battery of the embodiments of the present invention remarkably appear, the above technical solutions are illustrated by the following examples.
Example 1
The embodiment provides a preparation method of a lithium metal negative electrode, which comprises the following steps:
(21) taking a 28% ammonia solution;
(22) dissolving silver nitrate in ammonia water to obtain a mixed solution, wherein the concentration of the silver nitrate in the mixed solution is 2 mmol/L;
(23) soaking a commercial carbon fiber film with the thickness of 50 mu m into the mixed solution, keeping the temperature of 300 ℃ for 10-30 min under the nitrogen atmosphere, then cleaning the treated carbon fiber film by using deionized water, and drying the carbon fiber film at 80 ℃ to obtain a modified carbon fiber film, wherein amino and silver oxide particles are uniformly distributed on the surface of the film, the amino accounts for 80% of the total surface area of the film, and the silver oxide accounts for 20% of the total surface area of the film;
(24) heating a lithium belt with the weight 2 times that of the carbon fiber film to 260 ℃ to obtain molten lithium metal;
(25) immersing the carbon fiber film modified by the amino into molten lithium metal to ensure that the lithium metal fully wets the carbon fiber film modified by the amino, and cooling to obtain the carbon fiber film with the metallic lithium load of 3mAh/cm 2 Fig. 3 is an electron micrograph of the lithium metal negative electrode of (1).
Example 2
The embodiment provides a preparation method of a lithium metal negative electrode, which comprises the following steps:
(31) taking a 28% ammonia solution;
(32) dissolving silver nitrate in ammonia water to obtain a mixed solution, wherein the concentration of the silver nitrate in the mixed solution is 5 mmol/L;
(33) soaking a commercial carbon fiber film with the thickness of 20-100 microns into the mixed solution, keeping the temperature at 400 ℃ for 10-30 min under the nitrogen atmosphere, then cleaning the treated carbon fiber film by using deionized water, and drying the carbon fiber film at 80 ℃ to obtain a modified carbon fiber film, wherein amino and silver oxide particles are uniformly distributed on the surface of the film, the amino accounts for 60% of the total surface area of the film, and the silver oxide accounts for 40% of the total surface area of the film;
(34) heating a lithium belt with the weight 2 times that of the carbon fiber film to 260 ℃ to obtain molten lithium metal;
(35) immersing the carbon fiber film modified by the amino into molten lithium metal to ensure that the lithium metal fully wets the carbon fiber film modified by the amino, and cooling to obtain the carbon fiber film with the lithium metal loading capacity of 5mAh/cm 2 The lithium metal negative electrode of (1).
Comparative example 1
The method comprises the following steps:
(41) heating a lithium belt with the weight 2 times that of the carbon fiber film to 260 ℃ to obtain molten lithium metal;
(42) the carbon fiber film is immersed in molten lithium metal, which cannot sufficiently wet the carbon fiber film.
Comparative example 2
The comparative example provides a method of making a lithium metal anode, comprising the steps of:
(51) heating the lithium belt to 260 ℃ to obtain molten lithium metal;
(52) and (2) immersing the three-dimensional conductive framework with the N doping amount of 0.91% and the S doping amount of 1.03% into molten lithium metal to enable the lithium metal to fully wet the three-dimensional conductive framework, and cooling to obtain the lithium metal negative electrode, wherein the lithium metal loading capacity of the lithium metal negative electrode is 53%. The test shows that the capacity retention rate of the lithium metal negative electrode is 80% after 490 weeks of cyclic charge and discharge at 25 ℃ and 0.5 ℃.
Comparative example 3
This comparative example is substantially identical to example 1 except that the resulting modified carbon fiber film has amino groups and silver oxide particles uniformly distributed on the surface thereof, and the amino groups account for 50% of the total surface area of the film and the silver oxide accounts for 50% of the total surface area of the film. The test shows that the capacity retention rate of the obtained lithium metal negative electrode after 490 weeks of cyclic charge and discharge at 25 ℃ and 0.5 ℃ is 71%.
Comparative example 4
The comparative example is substantially the same as example 1, except that the carbon fiber film is immersed in the mixed solution and then kept at 250 ℃ for 15min, and the carbon fiber film is immersed in molten lithium metal, which cannot sufficiently wet the carbon fiber film.
Experimental example 1
The lithium metal negative electrode obtained in example 1 and the lithium metal negative electrode obtained in comparative example 1 were respectively formed into symmetrical batteries and subjected to cycle performance tests, and the results are shown in fig. 4. As can be seen from fig. 4, the symmetrical cell composed of the lithium metal negative electrode obtained in comparative example 1 exhibited a rise in overpotential after 100 hours of cycling, severe polarization, and a sudden drop in voltage after 200 hours of cycling, indicating the occurrence of short-circuiting. The symmetric battery composed of the lithium metal negative electrode obtained in the embodiment 1 of the invention can stably cycle for more than 500 hours, and the overpotential is about 0.2V, which shows that the battery prepared from the lithium metal negative electrode has good cycle stability by selecting the three-dimensional conductive framework modified by the amino group to load the lithium metal.
Experimental example 2
The lithium metal negative electrode obtained in example 1 and the lithium metal negative electrode obtained in comparative example 1 were respectively combined into a full cell to perform cycle performance tests, wherein the positive electrode material was NMC622, and the results are shown in table 1 and fig. 5. As can be seen from table 1 and fig. 5, even though the full cell of the lithium metal negative electrode composition obtained in comparative example 1 employs a higher N/P ratio, the cycle life thereof is only ten or more weeks; the full battery composed of the lithium metal cathode obtained in the embodiment 1 of the invention can still realize stable cycle for 500 weeks under a smaller N/P ratio, and the capacity retention rate is more than 83%. The embodiment of the invention selects the amino-modified three-dimensional conductive framework to load the lithium metal, and the battery made of the lithium metal cathode has good electrochemical performance.
Table 1 results of cycle performance test of lithium metal negative electrode obtained in example 1
Average discharge voltage Discharge capacity Capacity retention rate
Week
1 3.84V 185mAh/g N/A
At week 50 3.80V 179mAh/g 96.8％
Week
100 3.78V 175mAh/g 94.6％
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. The lithium metal negative electrode is characterized by comprising a three-dimensional conductive framework and metal lithium, wherein the metal lithium is loaded on the three-dimensional conductive framework, and amino groups are modified on the surface of the three-dimensional conductive framework.
2. The lithium metal anode of claim 1, wherein the modified area of the amino group is 60% to 100% of the surface area of the three-dimensional conductive framework.
3. The lithium metal negative electrode as claimed in claim 1 or 2, wherein the surface of the three-dimensional conductive framework is further modified with silver oxide particles, and the modified area of the silver oxide particles accounts for 0-40% of the surface area of the three-dimensional conductive framework.
4. The lithium metal anode of claim 1 or 2, wherein the metallic lithium is supported on the three-dimensional conductive skeleton at a capacity of 2mAh/cm 2 -10 mAh/cm 2 (ii) a And/or
The three-dimensional conductive framework is selected from at least one of a carbon fiber membrane, a carbon nanotube membrane and a graphene membrane; and/or
The thickness of the three-dimensional conductive framework is 20-100 μm.
5. A preparation method of a lithium metal negative electrode is characterized by comprising the following steps:
providing a three-dimensional conductive framework and liquid metal lithium, wherein the surface of the three-dimensional conductive framework is modified with amino;
and infiltrating the three-dimensional conductive framework into the liquid metal lithium to obtain the lithium metal cathode.
6. The preparation method of the lithium metal anode according to claim 5, wherein the method for modifying the surface of the three-dimensional conductive framework with the amino group comprises the following steps:
providing a three-dimensional conductive framework and ammonia water;
and soaking the three-dimensional conductive framework in the ammonia water, and performing heat treatment to obtain the three-dimensional conductive framework with the surface modified with amino.
7. The method of claim 6, wherein a silver salt is further added to the ammonia water.
8. The method for producing a lithium metal negative electrode according to claim 7, wherein the concentration of the aqueous ammonia is 20 wt.% to 30 wt.%; and/or
The concentration of the silver salt is 2mmol/L-5 mmol/L.
9. The method for preparing a modified three-dimensional conductive skeleton according to any one of claims 6 to 8, wherein the heat treatment is performed in a protective atmosphere, the temperature of the heat treatment is 300 ℃ to 400 ℃, and the time of the heat treatment is 10min to 30 min.
10. A lithium secondary battery comprising a positive electrode and a negative electrode, and an electrolyte disposed between the positive electrode and the negative electrode, wherein the negative electrode is the lithium metal negative electrode according to any one of claims 1 to 4, or the lithium metal negative electrode produced by the method for producing the lithium metal negative electrode according to any one of claims 5 to 9.
CN202110290078.1A 2021-03-18 2021-03-18 Lithium metal negative electrode, preparation method thereof and lithium secondary battery Pending CN115117303A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110290078.1A CN115117303A (en) 2021-03-18 2021-03-18 Lithium metal negative electrode, preparation method thereof and lithium secondary battery

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110290078.1A CN115117303A (en) 2021-03-18 2021-03-18 Lithium metal negative electrode, preparation method thereof and lithium secondary battery

Publications (1)

Publication Number Publication Date
CN115117303A true CN115117303A (en) 2022-09-27

Family

ID=83323505

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110290078.1A Pending CN115117303A (en) 2021-03-18 2021-03-18 Lithium metal negative electrode, preparation method thereof and lithium secondary battery

Country Status (1)

Country Link
CN (1) CN115117303A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115528213A (en) * 2022-10-31 2022-12-27 南昌大学 Lithium metal composite negative electrode material and preparation method thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115528213A (en) * 2022-10-31 2022-12-27 南昌大学 Lithium metal composite negative electrode material and preparation method thereof
CN115528213B (en) * 2022-10-31 2024-02-09 南昌大学 Lithium metal composite anode material and preparation method thereof

Similar Documents

Publication Publication Date Title
JP6006789B2 (en) battery
CN104518205B (en) The preparation method and zinc load and battery of zinc load
CN113054183A (en) Preparation method of CoNi bimetal organic framework derived carbon-sulfur composite material
CN111106310A (en) Preparation method of composite lithium metal negative electrode and battery containing composite lithium metal negative electrode
CN106058167A (en) Porous silicon-based alloy composite
CN111193005A (en) Copper foil current collector and preparation method and application thereof
CN112713260B (en) Flexible lithium metal battery cathode, preparation method thereof and lithium metal battery
CN106935838B (en) The method for preparing the LiFePO4 quaternary composite material of unidirectional preferential growth high electrochemical activity
CN112582610A (en) Flexible zinc ion battery based on conductive MOFs (metal-organic frameworks) based nano material
CN111646459A (en) Preparation method and application of boron-doped graphene material
CN106450509A (en) Electrolyte and battery
CN105070923A (en) Co3O4/Ru composite electrode with nano structure and preparation method and application of Co3O4/Ru composite electrode
CN114284475B (en) Preparation method of three-dimensional structured composite lithium metal anode and product thereof
CN115117303A (en) Lithium metal negative electrode, preparation method thereof and lithium secondary battery
CN114050226A (en) Negative electrode material and preparation method thereof, negative plate and lithium ion battery
CN110474023B (en) Fibrous nickel-bismuth battery and preparation method thereof
CN113488656A (en) 3D lithium-philic composite porous metal alloy current collector and preparation method and application thereof
CN115231622A (en) Method for preparing manganese cobalt oxygen by inducing low-temperature heat treatment of nanofiber template
CN115347140A (en) Surface-modified composite zinc-based negative electrode, preparation method and battery
CN109509879A (en) Clad anode material, preparation method and lithium ion battery altogether
CN115207304A (en) Graphite cathode composite material, preparation method thereof and lithium ion battery
CN108448069A (en) A kind of nickelic modification of lithium ion battery anode material method
CN111653724A (en) Surface-modified lithium nickel manganese oxide positive electrode material and preparation method thereof
CN114725347B (en) Three-dimensional porous carbon composite material for lithium-sulfur battery and preparation method thereof
CN117543038B (en) Modification preparation process of bipolar plate of proton exchange membrane fuel cell

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination