CN116190553A - Lithium anode and preparation method thereof - Google Patents

Lithium anode and preparation method thereof Download PDF

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Publication number
CN116190553A
CN116190553A CN202211442911.0A CN202211442911A CN116190553A CN 116190553 A CN116190553 A CN 116190553A CN 202211442911 A CN202211442911 A CN 202211442911A CN 116190553 A CN116190553 A CN 116190553A
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lithium
negative electrode
diaphragm
functional coating
metal
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王维坤
魏磊
金朝庆
曹高萍
王安邦
邱景义
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Institute Of Chemical Defense Chinese Academy Of Military Sciences
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Institute Of Chemical Defense Chinese Academy Of Military Sciences
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    • 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
    • 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
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • 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
    • 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
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H01M4/623—Binders being polymers fluorinated polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/423—Polyamide resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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Abstract

The invention discloses a lithium anode and a preparation method thereof, and belongs to the technical field of batteries. The lithium negative electrode comprises a modified diaphragm and a metal lithium negative electrode sheet, wherein the modified diaphragm is tightly attached to one side of the metal lithium negative electrode sheet, and the integrated lithium negative electrode is formed after hot-pressing treatment, so that the corrosion of the environment to the lithium negative electrode can be effectively reduced, and the storage and the processability of the lithium negative electrode are improved. The preparation method of the lithium anode has the characteristics of simple process, low cost, safety, reliability and the like, and the preparation process does not need to modify the lithium anode or a lithium metal interface, so that the preparation method is convenient for large-scale mass production. The integrated lithium cathode obtained by the invention is applied to a lithium metal battery, and the prepared lithium battery has longer cycle life and higher coulombic efficiency.

Description

Lithium anode and preparation method thereof
Technical Field
The invention discloses a lithium anode and a preparation method thereof, and belongs to the technical field of batteries.
Background
In recent years, lithium ion secondary batteries have been widely used in the fields of consumer electronics and communications. With the rapid development of electric vehicles, smart grids and large-scale energy storage fields, the performance of lithium ion batteries needs to be further improved, such as higher energy density and safety, longer cycle life and the like. However, due to its limited theoretical capacity, the current development and utilization have been approaching a limit.
The metal lithium has ultrahigh theoretical specific capacity and lowest oxidation-reduction potential, and is an ideal negative electrode material for constructing a next-generation high-specific-energy secondary battery system such as lithium oxygen, lithium sulfur, solid-state batteries and the like. But the metal lithium also has stronger activity, and is easy to react with organic electrolyte in the charge and discharge process to generate an SEI (Solid Electrolyte Interface ) film with anisotropy and instability; meanwhile, the non-uniformity of the metal lithium in the deposition process is very easy to grow into lithium dendrites, and the lithium dendrites possibly pierce through a diaphragm, so that serious potential safety hazards are brought; in addition, during the deposition process, the metal lithium will be accompanied by a huge volume expansion, and such volume expansion will lead to continuous rupture of the SEI film, so that the deposited lithium dendrites will fall off from the substrate, enter the electrolyte, expose fresh lithium, and the fresh lithium will consume the electrolyte continuously, thus the cycle is repeated, and the battery performance is reduced rapidly.
In order to solve the above technical problems, various solutions have been proposed by those skilled in the art, such as design of a novel three-dimensional current collector, electrolyte additives, solid electrolytes, or construction of a novel artificial modification layer, etc. The three-dimensional current collector can reduce the current density at the electrode surface and reduce the generation of lithium dendrites, but can reduce the utilization rate of lithium and the energy density of the battery as a whole. The electrolyte additive can participate in generating the SEI film in situ to guide the uniform distribution of lithium ions, but the electrolyte additive is continuously consumed until being completely consumed in the electrochemical circulation process, so that the original protection effect is lost. Solid-state electrolytes are expected to be safe for lithium anodes, but at present, there are still problems of large interfacial resistance and low ionic conductivity. The artificial modification layer is constructed on the surface of the lithium negative electrode, so that the growth of lithium dendrite can be effectively inhibited, and the side reaction between lithium metal and electrolyte is reduced, but the preparation process is often complex, the preparation environment is also severe, and the large-scale production is not facilitated. Therefore, those skilled in the art are required to develop a simple, feasible and low-cost method for protecting the lithium metal negative electrode, so as to improve the cycle life and the rate capability of the lithium metal battery and promote the commercial application of the lithium metal negative electrode.
Disclosure of Invention
The invention aims to solve the problems of poor storage and processability of a lithium negative electrode and provides a lithium negative electrode and a preparation method thereof. The preparation method has the advantages of simple process, low cost, safety and reliability, no need of directly processing the lithium negative electrode or modifying a lithium metal interface in the preparation process, contribution to improving the storage time and the processability of the lithium negative electrode, and convenience for large-scale application of the lithium negative electrode.
The invention solves the problems by adopting the technical scheme that: the lithium negative electrode comprises a modified diaphragm and a metal lithium negative electrode plate, wherein the modified diaphragm is tightly attached to one side of the metal lithium negative electrode plate to form an integrated lithium negative electrode;
the modified diaphragm comprises a diaphragm and a functional coating; the thickness of the diaphragm is 5-25 mu m, and the thickness of the functional coating is 0.5-20 mu m;
the membrane is one or more of PE membrane, PP/PE/PP three-layer membrane, bao Mdan coated membrane and aramid coated membrane.
The preparation method of the lithium anode comprises the following steps:
step one, a functional coating is coated on a diaphragm in advance to obtain a modified diaphragm;
step two, tightly attaching the modified diaphragm to one side of the metal lithium negative electrode, and forming the lithium negative electrode in a hot-pressing mode; the hot pressing mode is as follows: the hot pressing temperature of the double-plate hot press is regulated to be 30-80 ℃ and the hot pressing time is regulated to be 0.5-6 h; and the hot pressing pressure of the double-plate hot press is regulated to be 1-10 Mpa.
The functional coating comprises the following raw materials in parts by weight:
4-8 parts of lithium-containing compound
1 to 4 parts of organic polymer
1 part of adhesive
Wherein: the lithium-containing compound is more than one of nano-morphology lithium aluminum silicate, petalite, lepidolite, magnesium lithium silicate, hectorite, lithium lanthanum zirconium oxygen, lithium lanthanum zirconium tantalum oxygen, lithium germanium phosphorus sulfur and lithium phosphorus sulfur chlorine; or the lithium-containing compound is one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium dioxaborate, lithium difluorooxalato borate, lithium difluorophosphate, lithium difluorosulfimide, lithium bis (trifluoromethylsulfonyl) imide, lithium perchlorate, lithium nitrate, lithium nitride, lithium phosphide, lithium oxide, lithium sulfide, lithium selenide, lithium fluoride, lithium chloride, lithium bromide and lithium iodide;
the organic polymer is at least one of polyethylene oxide, polypropylene glycol, polyacrylamide, polyacrylic acid, polyacrylonitrile, polymethyl methacrylate, polyethylene carbonate, polyurethane, polydimethylsiloxane, perfluorinated sulfonic acid resin and lithiated perfluorinated sulfonic acid resin;
the binder is one or more of gelatin, acacia, chitosan, starch, cyclodextrin, polyvinylpyrrolidone, carboxymethyl cellulose, sodium carboxymethylcellulose, sodium alginate, styrene-butadiene rubber, LA133, polyvinylidene fluoride, polyethylene oxide, polyamide, polyethylene imine and polyimide.
The preparation method of the functional coating comprises the following steps:
mixing and dispersing the lithium-containing compound, the organic polymer and the binder in a solvent in a ball milling mode after the lithium-containing compound, the organic polymer and the binder are selected according to the weight ratio, and obtaining functional coating slurry after the lithium-containing compound, the organic polymer and the binder are uniformly dispersed;
uniformly coating the functional coating slurry on one surface of the diaphragm, and then drying at the temperature of 40-80 ℃ for 12-48 hours to obtain a modified diaphragm containing the functional coating;
wherein: the solvent is one or more of water, ethanol, isopropanol, acetone, ethylene glycol, tetrahydrofuran, dimethyl sulfoxide, N-methylpyrrolidone and N, N-dimethylformamide.
The invention has the beneficial effects that: the lithium negative electrode comprises a modified diaphragm and a metal lithium negative electrode sheet, wherein the modified diaphragm is tightly attached to one side of the metal lithium negative electrode sheet, and an integrated lithium negative electrode is formed after hot-pressing treatment, so that the corrosion of the environment to the lithium negative electrode can be effectively reduced, and the storage and the processability of the lithium negative electrode are improved. The preparation method of the lithium anode has the characteristics of simple process, low cost, safety, reliability and the like, and the preparation process does not need to modify the lithium anode or a lithium metal interface, so that the preparation method is convenient for large-scale mass production. The integrated lithium cathode is applied to a lithium metal battery, and the prepared lithium metal battery has longer cycle life and higher coulombic efficiency.
Drawings
FIG. 1 is a schematic flow chart of an integrated lithium anode preparation process
FIG. 2 is a lithium-lithium symmetric battery at 1mA cm -2 And a current density of 1mA h cm -2 Voltage-time curve for capacity of (2)
In the figure: a is a curve of a common lithium negative electrode, and b is a curve of an integrated lithium negative electrode;
the ordinate is the polarization voltage, unit V; the abscissa is the cycle time in h.
FIG. 3 SEM image of the surface of metallic lithium after 100 cycles of a lithium sulfur battery assembled from a common lithium negative electrode and an integrated lithium negative electrode at 0.5C
In the figure: a is an integrated lithium anode; b is a common lithium anode.
Fig. 4 SEM image of the surface of lithium negative electrode of lithium iron phosphate full battery assembled by common lithium negative electrode and integrated lithium negative electrode after 100 cycles at 0.5C magnification
In the figure: a is an integrated lithium anode; b is a common lithium anode.
FIG. 5 comparison graph of cycle performance and coulombic efficiency at 0.5C rate for a common lithium negative electrode and an integrated lithium negative electrode assembled lithium sulfur battery
In the figure: the curve a is the cycle performance of the common lithium negative electrode, the curve b is the cycle performance of the integrated lithium negative electrode, the curve c is the coulomb efficiency of the integrated lithium negative electrode, and the curve d is the coulomb efficiency of the common lithium negative electrode.
Detailed Description
The present invention will be described in detail with reference to the following examples and the accompanying drawings.
Example 1
The preparation method of the lithium anode comprises the following steps:
1) Sequentially weighing 1.2g of lithium magnesium silicate, 0.6g of lithiated perfluorinated sulfonic acid resin and 0.2g of gelatin, uniformly dispersing in water through ball milling, wherein the ball milling speed is 600r/min, and the ball milling time is 4 hours, so as to obtain uniformly mixed functional coating slurry;
2) Coating the functional coating slurry on one side of a polyethylene PE diaphragm with the thickness of 10 mu m by adopting a knife coating mode; drying for 12 hours through a vacuum oven at 60 ℃ to obtain a modified diaphragm modified by the functional coating; the functional coating can be uniformly and tightly adhered to the surface of the PE diaphragm, and the thickness of the functional coating is 2 mu m;
3) The modified diaphragm and the lithium metal negative electrode are placed on a double-plate hot press, hot pressed for 2 hours at 50 ℃ and 4Mpa, and combined together through a hot pressing mode to form the integrated lithium negative electrode.
Through testing, the prepared integrated lithium anode can be in air with the relative humidity of 20%, and the surface of the integrated lithium anode is not oxidized for 24 hours.
The functional coating material may be coated on the separator for lithium battery in one or more of spray coating, drop coating, spin coating, knife coating, roll coating, preferably knife coating.
Also provided in example 1 is a method of making a battery, comprising:
preparation of positive electrode: and taking the metal lithium sheet as a positive electrode.
Preparation of electrolyte: firstly, adding LiTFSI and LiNO into DOL/DME solution 3 Preparing electrolyte, ensuring the concentration of LiTFSI in the solution to be 1mol/L, and LiNO 3 Is 1.0wt%;
and (3) battery assembly: a CR2032 lithium symmetrical button cell was then assembled using the positive electrode, electrolyte, and lithium negative electrode prepared in example 1.
Example 2
1) Sequentially weighing 1.2g of lithium aluminum silicate, 0.4g of lithiated perfluorinated sulfonic acid resin and 0.2g of polyvinylidene fluoride, uniformly dispersing in N-methyl pyrrolidone by ball milling at a ball milling rotating speed of 800r/min for 10 hours, and obtaining the uniformly mixed functional coating slurry.
2) Coating the functional coating slurry on one side of a polypropylene PP diaphragm with the thickness of 25 mu m in a blade coating mode; drying for 12 hours through a vacuum oven at 60 ℃ to obtain a modified diaphragm modified by the functional coating; the functional coating can be uniformly and tightly adhered to the surface of the PP diaphragm, and the thickness of the functional coating is 10 mu m;
3) The modified diaphragm and the lithium metal negative electrode are placed on a double-plate hot press, hot pressed for 2 hours at 60 ℃ and 6Mpa, and combined together through a hot pressing mode to form the integrated lithium negative electrode.
The test shows that the prepared integrated negative electrode can not oxidize in the air with the relative humidity of 40% for 6 hours.
Also provided in example 2 is a method of making a battery, comprising:
preparation of positive electrode: selecting Ketjen black-sulfur composite material, conductive carbon black and polyvinylidene fluoride with the weight ratio of 41:4:5, uniformly mixing, coating, drying and obtaining the Ketjen black-sulfur positive electrode plate with the loading capacity of 2mg cm -2 The diameter is 14mm;
preparation of electrolyte: liTFSI and LiNO were first added to the DOL/DME solution 3 Preparing electrolyte, ensuring the concentration of LiTFSI in the solution to be 1mol/L, and LiNO 3 Is 1.0wt%;
and (3) battery assembly: a CR2032 lithium sulfur battery was then assembled using the positive electrode, the electrolyte, and the lithium negative electrode prepared in example 2.
Example 3
The other conditions were the same as in example 1 except that polyacrylic acid was used instead of the lithiated perfluorosulfonic acid resin. Then, the integrated lithium negative electrode prepared in example 3 was assembled together into a CR2032 lithium symmetric button cell using a metal lithium sheet as the positive electrode.
Example 4
Other conditions were the same as in example 1 except that lepidolite was used in place of lithium magnesium silicate. Then, the integrated lithium negative electrode prepared in example 4 was assembled together with a CR2032 lithium symmetrical button cell using a metal lithium sheet as the positive electrode.
Example 5
Other conditions were the same as in example 1 except that lithium nitrate was used instead of lithium magnesium silicate. Then, the integrated lithium negative electrode prepared in example 5 was assembled together with a CR2032 lithium symmetrical button cell using a metal lithium sheet as the positive electrode.
Example 6
The other conditions were the same as in example 1 except that LA133 was used instead of gelatin. Then, the integrated lithium negative electrode prepared in example 6 was assembled together with a CR2032 lithium symmetrical button cell using a metal lithium sheet as the positive electrode.
Example 7
The other conditions were the same as in example 2 except that polyvinylpyrrolidone was used instead of polyvinylidene fluoride. Then, a CR2032 lithium-sulfur battery was assembled with the integrated lithium negative electrode prepared in example 7 using the ketjen black-sulfur positive electrode sheet prepared in example 2.
Example 8
The other conditions were the same as in example 2 except that polyacrylonitrile was used instead of the lithiated perfluorosulfonic acid resin. Then, a CR2032 lithium-sulfur battery was assembled with the integrated lithium negative electrode prepared in example 8 using the ketjen black-sulfur positive electrode sheet prepared in example 2.
Example 9
Other conditions were the same as in example 2 except that laponite was used instead of lithium aluminum silicate. Then, a CR2032 lithium-sulfur battery was assembled with the integrated lithium negative electrode prepared in example 9 using the ketjen black-sulfur positive electrode sheet prepared in example 2.
Example 10
The other conditions were the same as in example 2 except that N, N-dimethylformamide was used in place of N-methylpyrrolidone. Then, a CR2032 lithium-sulfur battery was assembled with the integrated lithium negative electrode prepared in example 10 using the ketjen black-sulfur positive electrode sheet prepared in example 2.
Example 11
1) Sequentially weighing 1.0g of lithium aluminum silicate, 0.6g of lithiated perfluorinated sulfonic acid resin and 0.2g of polyvinylidene fluoride, uniformly dispersing in N-methyl pyrrolidone by ball milling at a ball milling rotating speed of 800r/min for 6 hours, and obtaining the uniformly mixed functional coating slurry.
2) Coating the functional coating slurry on one side of a polypropylene PP diaphragm with the thickness of 16 mu m by adopting a knife coating mode; drying for 12 hours through a vacuum oven at 60 ℃ to obtain a modified diaphragm modified by the functional coating; the functional coating can be uniformly and tightly adhered to the surface of the PP diaphragm, and the thickness of the functional coating is 5 mu m;
3) The modified diaphragm and the lithium metal negative electrode are placed on a double-plate hot press, hot pressed for 4 hours at 60 ℃ and 4Mpa, and combined together through a hot pressing mode to form the integrated lithium negative electrode.
Through testing, the prepared integrated negative electrode can be in air with the relative humidity of 30%, and the surface of the integrated negative electrode is not oxidized when the integrated negative electrode exists for 10 hours.
Comparative example 1
The integrated negative electrode prepared in example 1 was replaced with an unmodified general metal lithium sheet negative electrode in comparative example 1, and a CR2032 lithium symmetrical button cell was prepared according to the same battery preparation method as in example 1.
Comparative example 2
The integrated negative electrode prepared in example 2 was replaced with an unmodified general metal lithium sheet negative electrode in comparative example 2, and a CR2032 lithium symmetrical button cell was prepared according to the same battery preparation method as in example 2.
Comparative experiment 1
The CR2032 lithium symmetrical button cells prepared in example 1 and comparative example 1,the tests were performed under the same environment. Please refer to fig. 2, which shows the test cells prepared in example 1 and comparative example 1 at 1mA cm -2 And a current density of 1mAh cm -2 Voltage versus time curve for capacity of (c). It can be seen in FIG. 2b that the polarization potential of example 1 was 20mV and remained stable for more than 600h, whereas the polarization potential of comparative example 1 (FIG. 2 a) was as high as 50mV and showed a tendency of increasing polarization after 100 h. This is because the functional coating material of the integrated anode of example 1 spontaneously transfers to the surface of the lithium metal anode to form a uniform, dense, high ionic conductance SEI film, which can effectively promote lithium ion transport, guide lithium to deposit uniformly, and inhibit the formation of lithium dendrites, so that the interface structure is more stable, and the polarization potential can remain stable in long-time cycles. The SEI layer of comparative example 1 is located on the surface of lithium, repeated decomposition and generation of the SEI layer are caused by volume change of lithium in the cycling process, poor lithium ion conductors and dead lithium generated in the reaction process are mixed and attached to the surface of metal lithium, and non-uniform deposition of lithium is caused, so that polarization potential is continuously increased.
It can be seen from the above comparative experiment 1 that the cycle life of the integrated lithium negative electrode assembly prepared in example 1 is significantly improved and the interface resistance is significantly reduced, compared to the unmodified lithium metal sheet negative electrode.
Comparative experiment 2
The CR2032 lithium symmetrical button cells prepared in example 2 and comparative example 2 were tested under the same environment. Electrochemical performance of the cells was tested in a cell test system. The test temperature is 25 ℃, the test voltage interval is 1.8-2.5V, and the cyclic test is carried out under the condition of 0.5C, wherein 1 C=1675mAg -1 . Test results referring to fig. 5, fig. 5 is a graph showing comparison of cycle performance at 0.5C of lithium sulfur batteries assembled in example 2 and comparative example 2 according to the present invention. As can be seen from the comparison of fig. 5: the lithium sulfur battery using the integrated lithium cathode shows higher coulombic efficiency and better cycle stability, and the specific discharge capacity of the lithium sulfur battery is still 620mAh g after 200 times of cycle -1 450mAh g higher than ordinary lithium cathode -1 The method comprises the steps of carrying out a first treatment on the surface of the In the process of 200 cycles, the average coulombic efficiency is 99.91 percent and is higher than that of the common cycle98.1% of lithium negative electrode.
The difference in microscopic surfaces of the lithium anode of example 2 and comparative example 2 after 100 cycles can be seen by comparing fig. 3 and 4, and fig. 3 is an SEM image of the surface of the lithium anode of the assembled lithium sulfur battery of example 2 of the present invention after 100 cycles at 0.5C; fig. 4 is an SEM image of the surface of a lithium negative electrode of the lithium iron phosphate full battery assembled in comparative example 2 of the present invention after being cycled 100 times at 0.5C. As can be seen from fig. 3 and 4, the lithium metal surface using the integrated lithium negative electrode is smoother than that of the common metal lithium sheet negative electrode, and no significantly loose and porous lithium dendrite morphology is found. This again demonstrates that the use of an integrated negative electrode can accelerate lithium ion transport, effectively achieving uniform deposition of lithium, thereby inhibiting growth of lithium dendrites.
Compared with the common lithium cathode, the functional coating material of the integrated lithium cathode can be spontaneously transferred to the surface of the lithium metal cathode, so that lithium ion transmission can be effectively promoted, uniform deposition of lithium is guided, generation of lithium dendrite is inhibited, an interface structure is more stable, and polarization potential can be kept stable in long-time circulation. The preparation method is fully proved to be effective, and has important significance for processing and preparing the lithium metal negative electrode and popularizing and using the lithium metal battery.

Claims (4)

1. The lithium negative electrode is characterized by comprising a modified diaphragm and a metal lithium negative electrode plate, wherein the modified diaphragm is tightly attached to one side of the metal lithium negative electrode plate to form an integrated lithium negative electrode;
the modified diaphragm comprises a diaphragm and a functional coating; the thickness of the diaphragm is 5-25 mu m, and the thickness of the functional coating is 0.5-20 mu m;
the membrane is one or more of PE membrane, PP/PE/PP three-layer membrane, bao Mdan coated membrane and aramid coated membrane.
2. A lithium anode according to claim 1, characterized in that the method for preparing the lithium anode comprises the steps of:
step one, a functional coating is coated on a diaphragm in advance to obtain a modified diaphragm;
step two, tightly attaching the modified diaphragm to one side of the metal lithium negative electrode, and forming the lithium negative electrode in a hot-pressing mode; the hot pressing mode is as follows: the hot pressing temperature of the double-plate hot press is regulated to be 30-80 ℃ and the hot pressing time is regulated to be 0.5-6 h; and the hot pressing pressure of the double-plate hot press is regulated to be 1-10 Mpa.
3. The lithium anode of claim 1, wherein the functional coating comprises the following raw materials in parts by weight:
4-8 parts of lithium-containing compound
1 to 4 parts of organic polymer
1 part of adhesive
Wherein: the lithium-containing compound is more than one of nano-morphology lithium aluminum silicate, petalite, lepidolite, magnesium lithium silicate, hectorite, lithium lanthanum zirconium oxygen, lithium lanthanum zirconium tantalum oxygen, lithium germanium phosphorus sulfur and lithium phosphorus sulfur chlorine; or the lithium-containing compound is one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium dioxaborate, lithium difluorooxalato borate, lithium difluorophosphate, lithium difluorosulfimide, lithium bis (trifluoromethylsulfonyl) imide, lithium perchlorate, lithium nitrate, lithium nitride, lithium phosphide, lithium oxide, lithium sulfide, lithium selenide, lithium fluoride, lithium chloride, lithium bromide and lithium iodide;
the organic polymer is at least one of polyethylene oxide, polypropylene glycol, polyacrylamide, polyacrylic acid, polyacrylonitrile, polymethyl methacrylate, polyethylene carbonate, polyurethane, polydimethylsiloxane, perfluorinated sulfonic acid resin and lithiated perfluorinated sulfonic acid resin;
the binder is one or more of gelatin, acacia, chitosan, starch, cyclodextrin, polyvinylpyrrolidone, carboxymethyl cellulose, sodium carboxymethylcellulose, sodium alginate, styrene-butadiene rubber, LA133, polyvinylidene fluoride, polyethylene oxide, polyamide, polyethylene imine and polyimide.
4. The lithium anode according to claim 3, wherein the functional coating is prepared by the steps of:
mixing and dispersing the lithium-containing compound, the organic polymer and the binder in a solvent in a ball milling mode after the lithium-containing compound, the organic polymer and the binder are selected according to the weight ratio, and obtaining functional coating slurry after the lithium-containing compound, the organic polymer and the binder are uniformly dispersed;
uniformly coating the functional coating slurry on one surface of the diaphragm, and then drying at the temperature of 40-80 ℃ for 12-48 hours to obtain a modified diaphragm containing the functional coating;
wherein: the solvent is one or more of water, ethanol, isopropanol, acetone, ethylene glycol, tetrahydrofuran, dimethyl sulfoxide, N-methylpyrrolidone and N, N-dimethylformamide.
CN202211442911.0A 2022-11-18 2022-11-18 Lithium anode and preparation method thereof Pending CN116190553A (en)

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