Pre-lithiation method and apparatus for implementing same

Abstract

The present disclosure relates to a pre-lithiation process and an apparatus for implementing the same. The pre-lithiation method includes evaporating lithium onto a surface of the negative electrode to form a lithium layer thereon and heat treating the negative electrode.

Description

Technical Field

[0001] The present invention relates to a method for depositing lithium on the surface of a battery negative electrode before battery assembly and a device for implementing the same. Background Art

[0002] In recent years, secondary batteries using lithium or other alkali metals as energy storage technologies have been receiving attention. The storage and release of energy occur during the charging and discharging processes of the battery, but the insertion and extraction of alkali metals are not completely reversible. Therefore, depending on the irreversible reactions that occur, the capacity of the battery decreases as the charge / discharge cycles progress.

[0003] To solve this problem, a technology called prelithiation has been proposed during the manufacturing process of lithium-ion batteries.

[0004] Prelithiation is the process of adding lithium to the battery negative electrode before the completion of battery manufacturing, and it can improve the energy density of the battery and extend its cycle life. The irreversible capacity refers to the lithium capacity consumed by the solid-electrolyte interphase (SEI) formed on the negative electrode, which is mainly due to the decomposition of the electrolyte during the initial charging. The formation of SEI is inevitable in secondary lithium batteries.

[0005] Here, the technology using physical vapor deposition (PVD) is an excellent production method in the thin film field and is expected to be a method for improving the energy density of lithium-ion batteries because it can precisely control the amount of lithium required for prelithiation without being affected by moisture and oxygen (since the deposition of lithium is carried out in a vacuum). This method is expected to improve the energy density of lithium-ion batteries.

[0006] However, the reaction efficiency of prelithiation is related to the electrode structure. Since there is no electrolyte before battery assembly, the diffusion path of lithium is the contact points between the electrode active materials. Therefore, the performance of prelithiation is affected by the electrode density. In addition, during the assembly process after prelithiation, the electrodes are generally processed in a dry chamber but are affected by moisture and oxygen, thereby reducing the effect of prelithiation. The surface of the electrode active material is unstable due to being covered by a lithium film or reacting with lithium.

[0007] Currently, various prelithiation methods have been reported, but due to their respective defects, large-scale commercial applications have not been achieved. Summary of the Invention

[0008] [Technical Problem]

[0009] In view of the above problems, especially that the reaction efficiency of prelithiation is related to the structure of the negative electrode active material (such as the compaction density), and the prelithiated negative electrode is unstable before the assembly of the lithium-ion battery and is vulnerable to the atmospheric environment (such as O in dry air 2 and less H 2The present invention has been completed in view of the influence of (O).

[0010] The present invention aims to provide a prelithiation method that can be implemented with high reaction efficiency and can form a passivation layer for stabilizing the electrode surface, and an apparatus for realizing this method.

[0011] [Technical Solution]

[0012] One aspect of the present invention provides a prelithiation method, which includes evaporating lithium onto the surface of a negative electrode to form a lithium layer thereon and performing heat treatment on the negative electrode.

[0013] Another aspect of the present invention provides an apparatus for realizing the prelithiation method.

[0014] [Beneficial Effects]

[0015] The present invention can provide a prelithiation method that can be implemented with high reaction efficiency and can form a passivation layer for stabilizing the electrode surface, and an apparatus for realizing this method. Description of the Drawings

[0016] The following drawings attached to this specification are intended to illustrate exemplary embodiments of the present invention, and the spirit of the present invention can be more clearly understood from the drawings and the following description of the present invention. Therefore, the descriptions in the drawings should not be construed as limiting the scope of the present invention.

[0017] Figure 1 A scatter plot showing the relationship between ICE and the thickness of the Li film in the examples.

[0018] Figure 2 A flowchart showing the examples, a comparative example without a protective layer, and a comparative example without a protective layer and without heat treatment from left to right.

[0019] Figure 3 A diagram illustrating the activation (heating) treatment.

[0020] Figure 4 A diagram showing graphite (1) with a tap density of about 1.61 g / cm 3 graphite (2) with a tap density of about 1.29 g / cm 3 and SiO / C with a tap density of about 1.16 g / cm 3 SEM images of cross-sections (magnification of graphite (1) and (2): ×5K, magnification of SiO / C: ×3K).

[0021] Figure 5 A diagram showing the surface roughness of graphite (1), graphite (2), and SiO / C respectively, where Ra refers to the arithmetic mean roughness.

[0022] Figure 6For the layout of a mass production device, and Figure 7 For another layout of a mass production device, where the number 1 refers to the reaction chamber, the number 2 refers to the heating and winding chamber, the number 3 refers to the unwinding chamber, and the number 4 refers to the evaporation chamber. Detailed implementation

[0023] The prelithiation method of the present invention includes the formation of a lithium layer and heat treatment. The prelithiation method of the present invention further includes the formation of a surface protection layer carried out between the formation and heat treatment of the lithium layer.

[0024] <A: Formation of lithium layer>

[0025] The deposition system consists of a glove box, a transfer chamber, and a deposition chamber. The negative electrode target substrate is placed on a sample holder in the glove box with an argon atmosphere having a dew point of -50°C or lower, and is transferred to the deposition chamber through the transfer chamber. In order to obtain a high-quality lithium deposition film, the vacuum degree in the deposition chamber is set to H 2 O and O 2 The partial pressures of are less than 1E-4 Pa. The metallic lithium in the crucible placed in the deposition chamber is heated by a lamp heater, and the lithium deposition process is carried out while rotating the sample holder. The deposition rate and thickness are controlled using a thickness monitor with a quartz crystal microbalance (QCM). The deposition rate is set to and the thickness is set as needed.

[0026] <B: Formation of surface protection layer>

[0027] B-1: Using nitrogen

[0028] Lithium nitride is formed on the surface of the lithium layer by introducing nitrogen into the reaction chamber while rotating the substrate holder and maintaining the pressure at 150 Pa. A lithium nitride layer with a thickness of 100 nm is formed after 10 minutes.

[0029] B-2: Using nitrogen active species (such as an ion source)

[0030] Nitrogen is introduced while rotating the substrate holder in the deposition chamber, and nitrogen active species (ions and free radicals) are irradiated onto the substrate using an ion source unit (eH400, manufactured by KRI) under the conditions of a discharge voltage (Vf) of 150 V and a discharge current (If) of 1.0 A. The voltage during discharge is about 1E-2 Pa, and the distance between the emission source and the substrate is 200 mm. A lithium nitride layer of about 100 nm is formed after 1 minute.

[0031] <C: Heat treatment>

[0032] After forming the surface protective layer, evacuate the deposition chamber to 1E-4 Pa or lower, and heat the substrate to be processed to 130 °C using an infrared lamp heater to activate the prelithiation reaction. Considering the thermal damage to the binder compound in the negative electrode, a processing temperature of 130 °C or lower is desirable.

[0033] From the perspectives of cost and environmental load, an aqueous binder is used. Specifically, the heat-resistant temperatures of the binder based on styrene-butadiene rubber (SBR) and the binder based on polyacrylic acid (PAA) are 150 °C and 130 °C, respectively.

[0034] For the negative electrode current collector, a composite current collector having copper thin films on both sides of a resin film can be used in addition to copper foil, and the temperature should be considered according to the material of the resin film.

[0035] Regarding the specific materials of the resin film and their heat-resistant temperatures, polypropylene (PP) is 120 °C to 160 °C, polyethylene terephthalate (PET) is 150 °C, polyethylene naphthalate (PEN) is 180 °C, polyphenylene sulfide (PPS) is 200 °C to 240 °C, and polyimide (PI) is 300 °C or higher. However, from the perspective of cost, PP and PET are more practical (and are actually used).

[0036] In addition, the melting point of metallic lithium is 180 °C, so it cannot be processed, for example, at a temperature higher than 175 °C.

[0037] Meanwhile, since there is no Li-ion conductive electrolyte in the negative electrode, a processing temperature of 80 °C or higher is required to exceed the diffusion barrier between the grains of the negative electrode active material. Especially in the case of a low-density electrode, if the processing temperature is low, the diffusion barrier between the grains will not be exceeded, and lithium will remain in the pores and become inactivated, so the lithium required to form SEI cannot spread throughout the electrode.

[0038] The surface protective layer has a thickness of 20 nm to 2000 nm, depending on the roughness of the surface on which the surface protective layer is formed. In the surface treatment using N 2 gas, a uniform protective layer can be formed regardless of whether the surface to be treated is rough or thin, but the reaction rate is slow. In the surface treatment using plasma (ions), it is difficult to form a uniform protective film when the surface is rough, especially in the parts with surface shapes, so a thick film is required to form a film with high protective performance. However, due to the use of plasma, the reaction rate is very fast. The minimum film thickness required to obtain protective performance needs to be at least 20 nm, and since the surface roughness Ra of the negative electrode is about 1.0 μm, the maximum film thickness is considered to be 2000 nm.

[0039] The surface protective layer includes Li 3 N.

[0040] The surface protective layer is formed in a region that maintains a span longer than the main roller when observed horizontally or vertically, and the conveying speed is 1 m / min to 20 m / min.

[0041] The surface protective layer is formed in an atmosphere containing nitrogen or by irradiation with nitrogen ions.

[0042] The heat treatment is carried out in an annealing chamber equipped with a preheating mechanism and a winding roller with heat control. The lithium layer has a thickness of 0.5 μm to 10 μm, preferably 0.5 μm to 6 μm, and more preferably 0.5 μm to 2 μm.

[0043] The active material in the negative electrode includes or consists of the following substances: natural or artificial graphite, silicon, silicon oxide SiO x (0.5 ≤ x ≤ 1.5) or a combination thereof.

[0044] The heat treatment is carried out at a temperature of 80°C to 130°C in an atmosphere of rare gas or in an air atmosphere.

[0045] When the negative electrode has a tap density of 1.3 g / cm 3 to 1.6 g / cm 3 the heat treatment is maintained at 80°C for at least 6 minutes.

[0046] When the negative electrode has a tap density of 1.0 to 1.3 g / cm 3 the heat treatment is maintained at 130°C for at least 90 minutes.

[0047] In addition, the prelithiation method can be carried out in the device shown in Figure 6 or Figure 7 . In Figure 6 , the formation of the surface protective layer is carried out in the reaction chamber 1 and then the heat treatment is carried out in the heating and winding chamber 2 filled with rare gas. In Figure 7 , N 2 and rare gas are introduced simultaneously to carry out the formation of the surface protective layer and the heat treatment. As a result, the interlayer heat conduction is improved by heating in a higher pressure atmosphere.

[0048] The film is deposited in the main roller in the unwinding chamber 3. It should be clearly stated that the unwinding chamber 3 has the function of rolling out the flattened web.

[0049] When the surface protective layer is formed by gas reaction or plasma reaction, in order to carry out the surface treatment at a relatively fast film conveying speed, the winding roller and the unwinding roller are arranged on the same side, so it becomes a favorable device with a small footprint.

[0050] The wall surface of the reaction chamber 1 has a path, which should be an opening for the inflow or outflow of the web.

[0051] The heating and winding chamber 2 has Figure 6 and Figure 7 the heater elements shown as panel heaters. The rectangular panel heaters located above and below the winder (WD) are configured for temperature control by electricity or a cooling medium.

[0052] At the center of the winder in the heating and winding chamber 2, there is a shaft (not shown) that applies tension to the web and enables the web to be transported and rewound. A similar shaft also exists at the center of the unwinder in the unwinding chamber 3.

[0053] In the unwinding chamber 3, there is a main roller (MR) directly above the evaporator. Each main roller is configured such that the web can be transported at a deposition speed after providing the necessary tension to the web in cooperation with the shaft.

[0054] N 2 and rare gas should be introduced into the heating and winding chamber 2 where the atmosphere dew point is controlled to be below, for example, -50°C (as described above). This will limit the generation of H 3 O amount in the Li 2 N film and will also allow the reaction and heat treatment to be faster. The rare gas should be inert to Li and is typically an inert gas.

[0055] It is preferable to provide a differential pumping mechanism at the opening. This is because the differential pumping mechanism prevents nitrogen from flowing into the unwinding chamber 3 to maintain the purity of the Li layer as an evaporation film, and also enables the nitrogen partial pressure in the reaction chamber 1 to be increased compared to the unwinding chamber 3, enabling a faster nitriding reaction. This result allows for a smaller footprint.

[0056] A heating function can be imparted to the shaft in the winder section, as in the heating and winding chamber 2. As a result, the web wound in a coil shape in the winder section can have a cooling and heating source not only on the surface side but also on the core side. In other words, the web can be heated not only outside the three-dimensional shape coil but also inside it, so that each layer of the web forming the coil can have a uniform temperature, which achieves uniform heat treatment.

[0057] Examples

[0058] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The examples of the present invention can be modified into various forms, and the scope of the present invention should not be construed as being limited to the examples described in detail below. The examples of the present invention are provided to more comprehensively describe the present invention to those skilled in the art.

[0059] Example 1A: Preparation of the negative electrode sheet

[0060] The negative electrode sheet is prepared by coating the surface of a copper foil serving as a current collector with the following active material slurry, followed by heating, drying, and rolling steps.

[0061] The active material slurry is composed of graphite (1) as an active material, styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC) as binders, and carbon black as a conductive aid. The coating film is formed on one side of the copper foil with a thickness of 9 μm. After measuring the thickness and weight of the electrode, the electrode tap density is calculated to be 1.609 g / cm 3 .

[0062] Graphite (1) with a capacity density ≥ 300 mAh / g is purchased from Shenzhen Kejing Star Technology Co., Ltd.

[0063] B: Formation of the lithium layer

[0064] No lithium layer is formed on the negative electrode surface in Comparative Example 1-0. Lithium layers with thicknesses of 0.5 μm, 1.0 μm, 1.5 μm, 1.0 μm, or 1.0 μm are respectively formed on the negative electrode surfaces in Comparative Example 1-1, Comparative Example 1-2, Comparative Example 1-3, Comparative Example 1-4, or Comparative Example 1-5 via vacuum evaporation of lithium metal.

[0065] C: Formation of the surface protective layer

[0066] No surface protective layer is formed in Comparative Examples 1-0 to 1-5.

[0067] D: Heat treatment

[0068] No heat treatment is carried out in Comparative Examples 1-0 to 1-3. The heat treatment shown in Table 1 is achieved in Comparative Examples 1-4 and 1-5.

[0069] Evaluation process of battery performance

[0070] <Preparation of half-cell>

[0071] The negative electrodes prepared in Comparative Examples 1-0 to 1-5 are each cut into a size with a diameter of 14 mm and used as the working electrode, and a lithium foil (with a thickness of 50 μm) is cut into a size with a diameter of 16 mm and used as the positive electrode. The electrolyte is obtained by dissolving LiPF 6 at a concentration of 1 mol / L into a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) (mixing ratio is 50:50, and both are purchased from DoDo Chem. Inc.). A porous material made of polypropylene (Celgard: #2325) is used as the separator. Thus, half-cells are prepared.

[0072] <Performance Evaluation of Half-Cell>

[0073] The first discharge is carried out at a constant current of C / 10 (where 1C represents the current at which the battery can be fully discharged after one hour) until a cut-off voltage of 0.01 V is reached. The first charge is carried out at a low constant current of C / 10 until a cut-off voltage of 1.5 V is reached. The initial coulombic efficiency (ICE) of the half-cell is evaluated and obtained according to the following formula:

[0074] ICE (%) = (first charge capacity / first discharge capacity) × 100

[0075] The evaluation results in Comparative Examples 1-0 to 1-5 are shown in Table 1. As can be seen from Comparative Examples 1-0 to 1-3, when using a negative electrode material with a high tap density such as 1.609 g / cm 3 ³, the ICE increases with the increase in the lithium layer thickness. In Comparative Example 1-2, an ICE of 104.2% was obtained even without heat treatment through a lithium layer thickness of 1.0 μm, which is close to the theoretical value corresponding to 100% ICE. In addition, as can be seen from Comparative Examples 1-4 to 1-5, heat treatment has no significant effect on ICE.

[0076] Example 2

[0077] A: Preparation of Negative Electrode Sheet

[0078] The negative electrode sheet was prepared in the same manner as in Example 1 except that graphite (2) was used as the negative electrode active material.

[0079] Graphite (2) with a capacity density of ~330 mAh / g was purchased from Hefei Kejing Material Technology Co., Ltd.

[0080] The resulting negative electrode had a tap density of 1.285 g / cm 3 ³.

[0081] B: Formation of Lithium Layer

[0082] No lithium layer was formed on the surface of the negative electrode in Comparative Example 2-0. Lithium layers with thicknesses of 0.5 μm, 1.0 μm, 1.5 μm, or 3.0 μm were respectively formed on the surface of the negative electrode in Examples 2-1, 2-2, 2-3, or 2-4 via vacuum evaporation of lithium metal. Lithium layers with a thickness of 1.0 μm were formed in all of Examples 2-5 to 2-9.

[0083] C: Formation of Surface Protective Layer

[0084] No surface protective layer was formed in Comparative Example 2-0 and Examples 2-1 to 2-9.

[0085] D: Heat treatment

[0086] In Comparative Example 2-0 and Examples 2-1 to 2-4, heat treatment was not carried out. In Examples 2-5 to 2-9, heat treatment as shown in Table 1 was carried out.

[0087] Half-cells using the negative electrodes of Comparative Example 2-0 and Examples 2-1 to 2-9 were prepared and evaluated in the same manner as in Example 1. The ICE results of Comparative Example 2-0 and Examples 2-1 to 2-9 are shown in Table 1.

[0088] The following conclusions can be drawn from the ICE results in Comparative Example 2-0 and Examples 2-1 to 2-9.

[0089] In Example 2-2 where the formed lithium layer had a thickness of 1.0 μm and no heat treatment was carried out, the ICE was only 72.9%, even lower than that of Comparative Example 2-0.

[0090] In Example 2-4, an ICE of 105.5% was obtained by increasing the lithium layer thickness to 3.0 μm. This shows that although the ICE can be increased by increasing the lithium layer thickness, the prelithiation efficiency is low.

[0091] Compared with Example 2-2, in Example 2-8 or Example 2-9, even when the formed lithium layer had a thickness of 1.0 μm, ICE values as high as 105.9% or 104.0% were obtained by heat treatment at a heating temperature of 130 °C for 3 minutes or 10 minutes, respectively. This means that compared with Example 2-2, improved prelithiation efficiency has been obtained in Example 2-8 or Example 2-9.

[0092] Furthermore, it can be seen from Examples 2-5, 2-6, and 2-7 that when the thickness of the lithium layer was set to 1.0 μm and heat treatment was carried out at 80 °C, the ICE value could be increased by extending the heat treatment time. In Example 2-7, an ICE value of 103.3% was obtained by setting the heat treatment time to 20 minutes.

[0093] It is considered that in the negative electrode with a low tap density, the lithium formed on the electrode surface is difficult to diffuse into the electrode interior (due to the low diffusion coefficient between grains), causing lithium to precipitate and deactivate in the electrode pores, thus reducing the prelithiation efficiency. It has been further demonstrated that even for a negative electrode with a low tap density, the prelithiation efficiency can be improved by heat treatment.

[0094] Example 3

[0095] A: Preparation of negative electrode sheet

[0096] Using a tap density of 1.285 g / cm 3Graphite (2) is used as the negative electrode active material.

[0097] B: Formation of the lithium layer

[0098] Similar to other embodiments, in Examples 3-1 to 3-6, a lithium layer with a thickness of 0.5 μm, 1.0 μm, or 1.5 μm is formed by vacuum evaporating lithium metal onto the surface of the negative electrode, as shown in Table 2 below.

[0099] C: Formation of the surface protection layer

[0100] Then, in Examples 3-1 to 3-3, a lithium nitride protection layer of about 100 nanometers is formed by irradiating the negative electrode obtained in Step B with nitrogen ions.

[0101] In addition, in Examples 3-4 to 3-6, a lithium nitride protection layer of about 100 nm is also formed by exposing the negative electrode obtained in Step B to a nitrogen atmosphere of 150 Pa for 10 minutes.

[0102] Therefore, in Examples 3-1 to 3-6, a part of the lithium layer is nitrided, and a 100-nm Li 3 N protection film is formed, making the total thickness of the lithium layer and the lithium nitride protection layer in Examples 3-1 to 3-6 larger.

[0103] D: Heat treatment

[0104] In Examples 3-1 to 3-6, heat treatment is carried out at 130 °C for 10 minutes in a vacuum below 1E-4 Pa.

[0105] Half-cells using the negative electrodes in Examples 3-1 to 3-6 are prepared and evaluated in the same manner as in Example 1. The ICE results in Examples 3-1 to 3-6 are shown in Table 2.

[0106] For comparison, Comparative Example 2-0, Examples 2-1 to 2-4, and Examples 2-8 to 2-9 listed in Table 1 are also listed in Table 2.

[0107] It can be inferred from Table 2 that in the case of having a surface protection layer, ICE can increase with the increase in the thickness of the lithium layer. See Examples 3-1 to 3-3 or Examples 3-4 to 3-6.

[0108] In addition, from Examples 2-8, 3-2, and 3-5 in Table 2, it can be seen that when the thickness of the lithium layer is the same, forming a surface protection layer on the lithium layer has no significant effect on ICE, which means that even if a surface protection layer is formed on the lithium layer, comparable ICE results can be obtained.

[0109] Example 4 (batch type)

[0110] Graphite with a compaction density of 1.285 g / cm 3 is used as the negative electrode active material. A lithium layer with a thickness of 0.5 μm, 1.0 μm, or 1.5 μm is formed on the electrode surface by chemical vapor deposition. Then, the lithium layer is irradiated with nitrogen ions for 1 minute at a pressure of 1E-2 Pa, a discharge voltage of 150 V, and a discharge current of 1 A.

[0111] Example 5

[0112] A: Preparation of the negative electrode sheet

[0113] The negative electrode sheet is prepared by coating the surface of a copper foil serving as a current collector with the following active material slurry, followed by heating, drying, and rolling steps.

[0114] The active material slurry is prepared by mixing SiO / C as the active material, polyacrylic acid (PAA) as the binder, carbon black as the conductive additive, and distilled water.

[0115] The capacity density of SiO / C is 450 mAh / g.

[0116] The compaction density of the obtained negative electrode is 1.16 g / cm 3 .

[0117] B: Formation of the lithium layer

[0118] In Comparative Example 5-0, no lithium layer is formed on the negative electrode surface. In Examples 5-1 to 5-3, a lithium layer with a thickness of 3.5 μm is formed by vacuum evaporating lithium metal onto the negative electrode surface. In Examples 5-4 to 5-5, a lithium layer with a thickness of 4.5 μm or 6 μm is formed.

[0119] C: Formation of the surface protective layer

[0120] No surface protective layer is formed.

[0121] D: Heat treatment

[0122] In Examples 5-1 to 5-5, the heat treatment shown in Table 1 is carried out.

[0123] Half-cells using the negative electrodes of Comparative Example 5-0 and Examples 5-1 to 5-5 are prepared and evaluated in the same manner as in Example 1. The ICE results in Comparative Example 5-0 and Examples 5-1 to 5-5 are shown in Table 1.

[0124] As can be seen from Comparative Example 5-0 and Examples 5-1 to 5-5 in Table 1, the ICE value can be increased by increasing the thickness of the lithium layer. It is estimated that a lithium layer thickness of about 4.8 μm is required to obtain a 100% ICE value. In addition, in Example 5-1, even when heat-treated at 130 °C for 10 minutes, the prelithiation efficiency is low.

[0125] Table 1

[0126]

[0127] Table 2

[0128]

[0129] Certain embodiments and features are described using a set of numerical upper limits and a set of numerical lower limits. It should be understood that ranges including combinations of any two values (e.g., combinations of any lower limit value and any upper limit value, combinations of any two lower limit values, and / or combinations of any two upper limit values) are contemplated unless otherwise stated. Certain lower limits, upper limits, and ranges appear in one or more claims.

Claims

1. A pre-lithiation method comprising: evaporating lithium onto the surface of the negative electrode to form a lithium layer on the surface of the negative electrode; and The negative electrode is heat treated.

2. The pre-lithiation method according to claim 1, wherein the pre-lithiation method further comprises: After the lithium layer is formed and before the heat treatment, a surface protection layer is formed on the lithium layer.

3. The pre-lithiation method of claim 2, wherein the surface protection layer has a thickness of 20 nm to 2000 nm, depending on the roughness of the surface on which the surface protection layer is formed.

4. The pre-lithiation method of claim 2 or 3, wherein the surface protection layer comprises Li3N.

5. The pre-lithiation method according to any one of claims 2 to 4, wherein the surface protection layer is formed in a region maintaining a longer span than a main roller when viewed horizontally or vertically, and a conveying speed is 1 m / min to 20 m / min. 6 . The pre-lithiation method according to claim 2 , wherein the surface protection layer is formed in an atmosphere containing nitrogen or by irradiation with nitrogen ions.

7. The pre-lithiation method according to any one of claims 1 to 6, wherein the heat treatment is carried out in an annealing chamber equipped with a pre-heating mechanism and a winding roller with thermal control.

8. The pre-lithiation method of any one of claims 1 to 7, wherein the lithium layer has a thickness of 0.5 μm to 10 μm, preferably 0.5 μm to 6 μm, and more preferably 0.5 μm to 2 μm.

9. The pre-lithiation method according to any one of claims 1 to 8, wherein the active material in the negative electrode comprises or consists of the following: Natural or artificial graphite, silicon, silicon oxide SiO x (0.5≤x≤1.5) or a combination thereof. 10 . The pre-lithiation method according to claim 1 , wherein the heat treatment is performed at a temperature of 80° C. to 130° C. in an atmosphere of a rare gas or in an air atmosphere.

11. The pre-lithiation method of claim 10, wherein when the negative electrode has a 3 Up to 1.6g / cm 3 When the compaction density reaches 80°C, the heat treatment is maintained at 80°C for at least 6 minutes.

12. The pre-lithiation method of claim 10, wherein when the negative electrode has a 3 When the compaction density reaches 1000 Nm, the heat treatment is maintained at 130° C. for at least 90 minutes.

13. A device for implementing the pre-lithiation method according to any one of claims 1 to 12.

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