Negative electrode pre-lithiation method of vacuum thermal reduction metal lithium, lithium ion battery negative electrode and lithium ion battery

Abstract

The invention relates to the technical field of lithium ion batteries, and discloses a negative electrode pre-lithiation method for vacuum thermal reduction of metal lithium, a negative electrode of a lithium ion battery and the lithium ion battery. According to the method, a metal lithium layer needs to be fixed on the surface of an electrode by adopting metal as a reducing agent and adopting a physical vapor deposition device under a vacuum condition, the pre-lithiation degree of the negative electrode can be accurately controlled by controlling the thickness of the deposited metal lithium, and the pre-lithiation process of the electrode can be completed by standing the electrode deposited with the metal lithium for a period of time. According to the pre-lithiation method, the first-circle coulombic efficiency of the negative electrode can be obviously improved, and the first-circle irreversible capacity loss of the whole lithium ion battery can be reduced, so that the energy density of the lithium ion battery is improved.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion batteries, in particular to a negative electrode pre-lithiation method for vacuum thermal reduction of metallic lithium, a lithium ion battery negative electrode and a lithium ion battery. Background Art

[0002] Pre-lithiation is a method to improve the energy density and cycle life of lithium-ion batteries, especially for silicon-based high-capacity negative electrode materials. Due to the low first-cycle coulombic efficiency (less than 90%), the formation process will be accompanied by a capacity decay of more than 10%. By introducing metallic lithium or lithium-containing compounds and active substances into the positive or negative electrode to undergo chemical reactions, active lithium ions can be introduced to compensate for the loss of active lithium during the formation or cycle process.

[0003] Positive electrode pre-lithiation usually involves the introduction of some lithium-containing compounds into the positive electrode. During the charging process, the compounds decompose to produce active lithium ions that are added to the negative electrode, such as binary lithium compounds, such as Li 2 O. Li 2 O 2 , Li 2 S. Li 3 P and Li 3 N, ternary Li 2 NiO 2 , Li 5 FeO 4 and Li 6 CoO 4 , and nanocomposite Li based on the reverse conversion reaction 2 S / M, Li 2 O / M, LiF / M (M is Co or Fe, etc.). The decomposition process of these compounds is accompanied by the oxidation of the electrolyte. The gas or solid produced after decomposition will affect the electron / lithium ion transmission in the positive electrode material, increase the internal resistance of the positive electrode, and the specific capacity (usually less than 1000mAh / g) is lower than that of metallic lithium (3860mAh / g), which has limited effect on improving the energy density of the battery after lithium supplementation.

[0004] Negative electrode lithium replenishment usually uses a chemical reaction between metallic lithium and the negative electrode. Due to the strong reducing property of metallic lithium, the chemical reaction between the two can proceed spontaneously, which is a more direct and effective way to replenish lithium. Since there is no introduction of other heteroatoms, the negative impact on the battery is smaller than the positive electrode lithium replenishment process. The forms of metallic lithium used include: lithium foil, lithium sheet, lithium powder, etc. However, the strong reducing property of metallic lithium is very dangerous, and the cost of raw materials is high (about 800,000 yuan / ton), which greatly increases the production cost of the lithium replenishment process. Summary of the invention

[0005] The technical problem to be solved by the present invention is: to overcome the deficiencies in the prior art and provide a method for pre-lithiation of a negative electrode by vacuum thermal reduction of metallic lithium, a negative electrode of a lithium ion battery and a lithium ion battery. In the present invention, metallic lithium is prepared by reducing a lithium-containing compound in a vacuum by a reducing agent, and the metallic lithium is deposited on the negative electrode to directly react with the negative electrode in a biochemical manner, and the pre-lithiation negative electrode is obtained after standing for a period of time. The present invention avoids the introduction of metallic lithium raw materials in the process of replenishing the negative electrode lithium, reduces the cost of replenishing the negative electrode lithium, and improves the safety of replenishing the negative electrode lithium.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A method for pre-lithiation of negative electrode by vacuum thermal reduction of metallic lithium comprises the following steps:

[0008] Step S1, preparation of the negative electrode to be lithiated,

[0009] The negative electrode active material, the conductive agent, the binder and water are mixed evenly to prepare a negative electrode slurry, and then the negative electrode slurry is coated on the surface of the negative electrode, and dried at 80° C. to obtain a negative electrode to be pre-lithiated;

[0010] Step S2, preparation of reduction mixture mass,

[0011] The reducing agent and the lithium-containing compound are uniformly mixed to obtain a reducing mixture, and then the reducing mixture is pressed into a mass to obtain a reducing mixture mass;

[0012] Step S3, preparation of pre-lithiation,

[0013] The reduced mixture mass obtained in step S2 is placed in a container, and the negative electrode to be pre-lithiated obtained in step S1 is placed on the reduced mixture mass. The reduced mixture mass is vacuum heated, and the metallic lithium in the lithium-containing compound is reduced and deposited on the surface of the negative electrode to be pre-lithiated, thereby obtaining a preliminary product of the pre-lithiated negative electrode;

[0014] Step S4, cooling the pre-lithiated negative electrode obtained in step S3 to room temperature, taking it out, and placing it in an inert atmosphere for more than 48 hours to complete the negative electrode lithium replenishment process.

[0015] Furthermore, in step S1, the negative electrode active material is one or more of graphite, silicon, silicon oxide, and porous silicon carbon, the conductive agent is one or more of acetylene black, Ketjen black, Super P superconducting carbon black, graphene, and carbon nanotubes, and the binder is one or more of sodium carboxymethyl cellulose, styrene-butadiene rubber, sodium alginate, lithium polyacrylate, polyacrylic acid, polyvinylidene fluoride, poly(vinylidene fluoride-co-hexafluoropropylene), and polytetrafluoroethylene.

[0016] Furthermore, in the negative electrode slurry of step S1, the mass percentage of the negative electrode active material is 70% to 96%, the mass percentage of the conductive agent is 2% to 15%, and the mass percentage of the binder is 2% to 15%.

[0017] Furthermore, in step S2, the molar ratio of the reducing agent to the lithium-containing compound in the reduction mixture is 1:(1-2.4).

[0018] Furthermore, in step S2, the reducing agent is one or more of Al, Mg, Si, Ti, V, Cr, Mn, Fe, Co, Zn, Zr, Nb, Ta, Mo, and W, preferably one or more of Al, Mg, Si, Ti, Mn, and V;

[0019] The lithium-containing compound is Li 2 O. Li 2 O 2 , Li 2 CO 3 , Li 2 C 2 O 4 、LiAlO 2 , Li 2 SiO 3 , Li 4 SiO 4 , Li 2 Si 2 O 5 、LiOH、LiAlSi 2 O 6 、LiAISiO 4 , CH 3 One or more of COOLi, preferably Li 2 O. Li 2 CO 3 、LiAlO 2 , LiOH.

[0020] Furthermore, in the vacuum heating in step S3, the heating temperature is 500-1000° C. and the vacuum degree is 0.002-0.2 Pa.

[0021] Furthermore, the vacuum heating method in step S3 is one of vacuum resistance heating evaporation, vacuum electron beam evaporation, vacuum high frequency heating evaporation, vacuum laser heating evaporation, and vacuum arc heating evaporation; preferably, vacuum electron beam evaporation or vacuum resistance heating evaporation.

[0022] Furthermore, in step S3, the deposition thickness of the metallic lithium on the surface of the negative electrode to be pre-lithiated is 1 to 10 μm.

[0023] Furthermore, the inert atmosphere in step S4 is one or more of argon, nitrogen, helium, and carbon dioxide; preferably argon or carbon dioxide; and the standing time in step S4 is determined according to the amount of deposited metallic lithium.

[0024] A lithium ion battery negative electrode is prepared by the negative electrode pre-lithiation method of vacuum thermal reduction of metallic lithium.

[0025] A lithium ion battery comprises the above-mentioned lithium ion battery negative electrode.

[0026] The beneficial effects of the present invention are as follows: the present invention has a reasonable design and a simple method. The lithium-containing compound is reduced by a reducing agent in a vacuum to prepare metallic lithium. The metallic lithium is deposited on the surface of the negative electrode to be pre-lithiated. Due to the strong reducing property of metallic lithium, it will spontaneously react with the active material in the negative electrode in a solid state chemical reaction. The reaction product of metallic lithium and graphite is a lithium-graphite intercalation chemical (LiC 6 ,LiC 12 ,LiC 24 The reaction product of metallic lithium and silicon dioxide is lithium silicate (Li 2 SiO 3 ,Li 2 Si 2 O 5 ,Li 4 SiO 4 ) and lithium oxide, the reaction product of metallic lithium and silicon is lithium silicon alloy (Li x Si, x≤3.75); the pre-lithiated negative electrode product is left to stand for a period of time, and the metallic lithium directly reacts with the negative electrode to be pre-lithiated to obtain a pre-lithiated lithium-ion battery negative electrode; the present invention can avoid the introduction of lithium metal as a raw material, and can reduce the danger and production cost of the lithium replenishment process. Since the process of reducing the metallic lithium is carried out in a vacuum, the safety hazard is greatly avoided. The capacity of the lithium replenishment can be accurately controlled by controlling the deposition thickness of the metallic lithium, and the energy density of the lithium-ion battery can be increased by 5% to 20%, which is of great significance to promoting the development of high-energy and low-cost lithium-ion battery technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 1 is the first cycle charge and discharge curve of the half-cell of Examples 1, 2, 3 and Comparative Example 1;

[0029] Figure 2 is the XRD pattern of the reduced slag in the crucible of Example 1;

[0030] Figure 3 is the XRD pattern of the reduced slag in the crucible of Example 2;

[0031] Figure 4 This is the XRD diagram of the reduced slag in the crucible of Example 3. DETAILED DESCRIPTION

[0032] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0033] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form also includes the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this description, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0034] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1

[0036] A method for pre-lithiation of negative electrode by vacuum thermal reduction of metallic lithium comprises the following steps:

[0037] Step S1, preparation of the negative electrode to be lithiated,

[0038] Graphite, porous silicon carbon, acetylene black, sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber and water are mixed uniformly in a weight ratio of 75:15:5:3:2:100 to prepare a negative electrode slurry, and then the negative electrode slurry is coated on the surface of a copper foil and dried at 80° C. to obtain a pre-lithiation negative electrode;

[0039] Step S2, preparation of reduction mixture mass,

[0040] The reducing agent Al and the lithium-containing compound Li 2 CO 3 The mixtures are uniformly mixed in a molar ratio of 1:2 to obtain a reduced mixture, and then the reduced mixture is pressed into a mass to obtain a reduced mixture mass;

[0041] Step S3, preparation of pre-lithiation,

[0042] The reduction mixture mass obtained in step S2 is placed in a crucible, and the negative electrode to be lithiated obtained in step S1 is placed on the reduction mixture mass. The mixture is heated by vacuum electron beam evaporation, the vacuum degree is 0.005-0.1 Pa, the crucible is heated to 500°C, and the reduction is heated for 1 hour. During the reduction process, Li 2 CO 3 First decompose to generate Li 2 O and CO 2 gas, then metal Al and Li 2 O undergoes chemical reaction to produce LiAlO 2 and metallic lithium gas, the gaseous metallic lithium condenses on the surface of the low-temperature negative electrode, completing the process of depositing metallic lithium, the deposition thickness of the metallic lithium is 1 μm, and the pre-lithiated negative electrode is obtained; the chemical reaction occurring in this step is as follows:

[0043] Li 2 CO 3 =Li 2 O+CO 2 ;

[0044] Al+2Li 2 O=LiAlO 2 +3Li;

[0045] Step S4, cooling the pre-lithiated negative electrode obtained in step S3 to room temperature, taking it out, and placing it in an argon atmosphere for 48 hours to allow the chemical reaction between the metallic lithium and the negative electrode to be complete, completing the negative electrode lithium replenishment process, and obtaining a finished lithium-ion battery negative electrode.

[0046] A lithium-ion battery, which uses metallic lithium and a lithium-supplemented negative electrode to assemble a CR2032 type half-cell, a diaphragm using Celgard2400, and an electrolyte containing LiPF with a molar concentration of 1 mol / L 6 solution, EC (diethyl carbonate) in a mass ratio of 1:1:1), a mixture of EMC (ethyl methyl carbonate) and DMC (dimethyl carbonate), and FEC (fluoroethylene carbonate) with a mass fraction of 2%.

[0047] Example 2

[0048] A method for pre-lithiation of negative electrode by vacuum thermal reduction of metallic lithium comprises the following steps:

[0049] Step S1, preparation of the negative electrode to be lithiated,

[0050] Graphite, porous silicon carbon, acetylene black, sodium carboxymethyl cellulose, styrene-butadiene rubber and water are mixed uniformly in a weight ratio of 75:15:5:3:2:100 to prepare a negative electrode slurry, and then the negative electrode slurry is coated on the surface of a copper foil and dried at 80° C. to obtain a negative electrode to be pre-lithiated;

[0051] Step S2, preparation of reduction mixture mass,

[0052] The reducing agent Ti and the lithium-containing compound LiOH are uniformly mixed in a molar ratio of 1:2.4 to obtain a reducing mixture, and then the reducing mixture is pressed into a mass to obtain a reducing mixture mass;

[0053] Step S3, preparation of pre-lithiation,

[0054] The reduction mixture mass obtained in step S2 is placed in a crucible, and the negative electrode to be lithiated obtained in step S1 is placed on the reduction mixture mass. Vacuum resistance heating is performed for evaporation. The vacuum degree is 0.003-0.2 Pa. The crucible is heated at 850°C and heated for reduction for 1 hour. During the reduction process, LiOH first decomposes to generate gaseous H 2 O and Li 2 O, gaseous H 2 O is exhausted by vacuum pump, and then metal Ti and Li 2 O undergoes a chemical reaction to produce Ti oxide and metallic lithium gas, and the gaseous metallic lithium condenses on the surface of the low-temperature negative electrode to complete the process of depositing metallic lithium. The deposition thickness of the metallic lithium is 1.5 μm, and a pre-lithiated negative electrode is obtained;

[0055] Step S4, cooling the pre-lithiated negative electrode obtained in step S3 to room temperature, taking it out, and placing it in an argon atmosphere for 50 hours to allow the chemical reaction between the metal lithium and the negative electrode to be complete, completing the negative electrode lithium replenishment process, and obtaining a finished lithium-ion battery negative electrode.

[0056] A lithium-ion battery, which uses metallic lithium and a lithium-supplemented negative electrode to assemble a CR2032 type half-cell, a diaphragm using Celgard2400, and an electrolyte containing LiPF with a molar concentration of 1 mol / L 6 solution, a mixture of EC, EMC and DMC in a mass ratio of 1:1:1, and FEC with a mass fraction of 2%.

[0057] Example 3

[0058] A method for pre-lithiation of negative electrode by vacuum thermal reduction of metallic lithium comprises the following steps:

[0059] Step S1, preparation of the negative electrode to be lithiated,

[0060] Graphite, porous silicon carbon, acetylene black, sodium carboxymethyl cellulose, styrene-butadiene rubber and water are mixed uniformly in a weight ratio of 75:15:5:3:2:100 to prepare a negative electrode slurry, and then the negative electrode slurry is coated on the surface of a copper foil and dried at 80° C. to obtain a negative electrode to be pre-lithiated;

[0061] Step S2, preparation of reduction mixture mass,

[0062] The reducing agent Mn and the lithium-containing compound Li 2 O are mixed uniformly in a molar ratio of 1:1 to obtain a reduced mixture, and then the reduced mixture is pressed into a mass to obtain a reduced mixture mass;

[0063] Step S3, preparation of pre-lithiation,

[0064] The reduction mixture mass obtained in step S2 is placed in a crucible, and the negative electrode to be lithiated obtained in step S1 is placed on the reduction mixture mass, and the mixture is evaporated by vacuum resistance heating. The crucible is heated to 1000°C at a vacuum degree of 0.002-0.05 Pa and the reduction is carried out for 1 hour. During the reduction process, the metal Mn directly reacts with Li 2 O undergoes a chemical reaction to produce Mn oxide and metallic lithium gas. The gaseous metallic lithium condenses on the surface of the low-temperature negative electrode to complete the process of depositing metallic lithium. The deposition thickness of the metallic lithium is 2 μm, and a pre-lithiated negative electrode product is obtained.

[0065] Step S4, cooling the pre-lithiation negative electrode obtained in step S3 to room temperature and then taking it out, placing it in an argon atmosphere for 72 hours to allow the chemical reaction between the metal lithium and the negative electrode to be complete, completing the negative electrode lithium replenishment process, and obtaining a finished lithium-ion battery negative electrode.

[0066] A lithium-ion battery, which uses metallic lithium and a lithium-supplemented negative electrode to assemble a CR2032 type half-cell, a diaphragm using Celgard2400, and an electrolyte containing LiPF with a molar concentration of 1 mol / L 6 solution, a mixture of EC, EMC and DMC in a mass ratio of 1:1:1, and FEC with a mass fraction of 2%.

[0067] Comparative Example 1

[0068] Preparation of the negative electrode to be lithiated in this comparative example: Graphite, porous silicon carbon, acetylene black, sodium carboxymethyl cellulose, styrene-butadiene rubber and water are uniformly mixed in a weight ratio of 75:15:5:3:2:100 to prepare a negative electrode slurry, which is then coated on the surface of a copper foil and dried at 80°C to obtain a negative electrode to be pre-lithiated.

[0069] In this comparative example, a lithium-ion battery is assembled with metallic lithium and the above-mentioned non-lithium-supplemented negative electrode into a CR2032 half-cell, the separator is Celgard2400, and the electrolyte is a LiPF 6 solution, a mixture of EC, EMC and DMC in a mass ratio of 1:1:1, and FEC with a mass fraction of 2%.

[0070] The lithium ion batteries prepared in Examples 1, 2, 3 and Comparative Example 1 were subjected to a half-cell first cycle charge and discharge test. The test results are shown in Table 1. The test curves are shown in Figure 1 shown.

[0071] Table 1 First cycle charge and discharge data of half-cells of Examples 1, 2, 3 and Comparative Example 1

[0072] From Table 1 and Figure 1 It can be seen that compared with Comparative Example 1, the first-cycle coulombic efficiency of the negative electrode half-cells of Examples 1 to 3 is increased by 3.6%, 5.9% and 7.8%, respectively, and the corresponding first-cycle irreversible capacity loss is reduced from 49.9 mAh / g without lithium supplementation to 26.9 mAh / g, 13.8 mAh / g and 3.3 mAh / g, respectively. When the negative electrode after lithium supplementation is matched with the positive electrode of the full battery, the lithium loss of the positive electrode of the full battery will also be reduced, and the reversible capacity of the battery will be increased, thereby improving the energy density of the lithium-ion battery.

[0073] The XRD patterns of the reduced slag in the crucibles of Example 1, Example 2 and Example 3 are as follows: Figure 2 , Figure 3 and Figure 4 shown.

[0074] Depend on Figure 2 to Figure 4 It can be seen that lithium salts can be reduced by using metals with strong reducing properties such as Al, Ti, and Mn, and the products are metallic lithium and high-valent lithium-containing metal oxides. When Al is used as a reducing agent, the product is LiAlO 2 , the Al in the reducing agent is oxidized to +3. When Ti is used as the reducing agent, the product components are Li 4 TiO 4 , Li 2 TiO 3 and Ti 2 O mixture, Ti valence is +4, +3 and +0.5 respectively. When metal Mn is used as a reducing agent, the product is MnO and Li 6 MnO 4 , Mn is oxidized to +2.

[0075] In summary, the present invention has a reasonable design and a simple method. A lithium-containing compound is reduced by a reducing agent in a vacuum to prepare metallic lithium, and the metallic lithium is deposited on the surface of the negative electrode to be pre-lithiated to obtain a pre-lithiated negative electrode initial product; after the pre-lithiated negative electrode initial product is left to stand for a period of time, the metallic lithium directly reacts with the negative electrode to be pre-lithiated to obtain a pre-lithiated lithium-ion battery negative electrode; the present invention can avoid the introduction of lithium metal as a raw material, and can reduce the danger and production cost of the lithium replenishment process. Since the process of reducing the metallic lithium is carried out in a vacuum, safety hazards are greatly avoided. The capacity of the lithium replenishment can be accurately controlled by controlling the deposition thickness of the metallic lithium, and the energy density of the lithium-ion battery can be increased by 5% to 20%, which is of great significance for promoting the development of high-energy and low-cost lithium-ion battery technology.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for negative electrode pre-lithiation by vacuum thermal reduction of metallic lithium, characterized in that: The specific steps include: Step S1, preparation of the negative electrode to be lithiated, The negative electrode active material, the conductive agent, the binder and water are mixed evenly to prepare a negative electrode slurry, and then the negative electrode slurry is coated on the surface of the negative electrode, and dried at 80° C. to obtain a negative electrode to be pre-lithiated; Step S2, preparation of reduction mixture mass, The reducing agent and the lithium-containing compound are uniformly mixed to obtain a reducing mixture, and then the reducing mixture is pressed into a mass to obtain a reducing mixture mass; Step S3, preparation of pre-lithiation, The reduced mixture mass obtained in step S2 is placed in a container, and the negative electrode to be pre-lithiated obtained in step S1 is placed on the reduced mixture mass, and vacuum heating is performed, so that the metallic lithium in the lithium-containing compound is reduced and deposited on the surface of the negative electrode to be pre-lithiated, thereby obtaining a preliminary product of the pre-lithiated negative electrode; Step S4, cooling the pre-lithiated negative electrode obtained in step S3 to room temperature, taking it out, and placing it in an inert atmosphere for more than 48 hours to complete the negative electrode lithium replenishment process.

2. The method for negative electrode pre-lithiation by vacuum thermal reduction of metallic lithium according to claim 1, characterized in that: In step S1, the negative electrode active material is one or more of graphite, silicon, silicon oxide, and porous silicon carbon, the conductive agent is one or more of acetylene black, Ketjen black, Super P superconducting carbon black, graphene, and carbon nanotubes, and the binder is one or more of sodium carboxymethyl cellulose, styrene-butadiene rubber, sodium alginate, lithium polyacrylate, polyacrylic acid, polyvinylidene fluoride, poly(vinylidene fluoride-co-hexafluoropropylene), and polytetrafluoroethylene.

3. The method for negative electrode pre-lithiation by vacuum thermal reduction of metallic lithium according to claim 1, characterized in that: In the negative electrode slurry of step S1, the mass percentage of the negative electrode active material is 70% to 96%, the mass percentage of the conductive agent is 2% to 15%, and the mass percentage of the binder is 2% to 15%.

4. The method for negative electrode pre-lithiation by vacuum thermal reduction of metallic lithium according to claim 1, characterized in that: In the step S2, the molar ratio of the reducing agent to the lithium-containing compound in the reduction mixture is 1:(1-2.4).

5. The method for negative electrode pre-lithiation by vacuum thermal reduction of metallic lithium according to claim 1, characterized in that: In step S2, the reducing agent is one or more of Al, Mg, Si, Ti, V, Cr, Mn, Fe, Co, Zn, Zr, Nb, Ta, Mo, and W; the lithium-containing compound is one or more of Li2O, Li2O2, Li2CO3, Li2C2O4, LiAlO2, Li2SiO3, Li4SiO4, Li2Si2O5, LiOH, LiAlSi2O6, LiAISiO4, and CH3COOLi.

6. The method for negative electrode pre-lithiation by vacuum thermal reduction of metallic lithium according to claim 1, characterized in that: In the vacuum heating of step S3, the heating temperature is 500-1000° C. and the vacuum degree is 0.002-0.2 Pa; The vacuum heating method in step S3 is one of vacuum resistance heating evaporation, vacuum electron beam evaporation, vacuum high frequency heating evaporation, vacuum laser heating evaporation, and vacuum arc heating evaporation.

7. The method for negative electrode pre-lithiation by vacuum thermal reduction of metallic lithium according to claim 1, characterized in that: In the step S3, the deposition thickness of the metallic lithium on the surface of the negative electrode to be pre-lithiated is 1 to 10 μm.

8. The method for negative electrode pre-lithiation by vacuum thermal reduction of metallic lithium according to claim 1, characterized in that: In step S4, the inert atmosphere is one or more of argon, nitrogen, helium, and carbon dioxide.

9. A negative electrode for a lithium ion battery, characterized in that: The lithium-ion battery negative electrode is prepared by the negative electrode pre-lithiation method of vacuum thermal reduction of metallic lithium as described in any one of claims 1 to 8.

10. A lithium ion battery, characterized in that: The lithium-ion battery comprises the lithium-ion battery negative electrode as claimed in claim 9.

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