KR20210137291A - Negative electrode for lithium secondary battery, method of preparing the saem, and lithium secondary battery using the same - Google Patents

Abstract

The present embodiments relate to a negative electrode for a lithium secondary battery, a manufacturing method thereof, and a lithium secondary battery using the same. According to an embodiment, provided is the negative electrode for a lithium secondary battery a film, including: a current collector; a negative electrode active material layer positioned on the current collector; and a film that contains fluorine (F) and is positioned on the surface of the negative electrode active material layer, wherein the negative electrode active material layer is pre-lithiated, and the film contains 0.3% by weight or more of fluorine (F) based on the entire film.

Description

Anode for lithium secondary battery, manufacturing method thereof, and lithium secondary battery using same

A negative electrode for a lithium secondary battery, a manufacturing method thereof, and a lithium secondary battery using the same.

In lithium-ion batteries, not only a solid electrolyte interface (SEI) is formed at the negative electrode during the initial charging process, but also active lithium loss occurs due to irreversible lithium plating and side reactions, so that the actual reversible capacity is reduced. A decrease occurs, which is called an initial irreversible phenomenon.

This initial irreversible phenomenon is prominent when a silicon-based material or a silicon oxide-based material is used as a negative active material compared to a carbon-based negative active material. In particular, in the case of a silicon oxide-based material, Li ₂ O, Li ₄ SiO Since it is easy to generate irreversible materials such as, the initial irreversible phenomenon is more severe, and as a result, there is a problem that the initial Coulombic Efficiency (ICE) is very low at the level of 70%.

Therefore, in order to use high-capacity silicon-based and silicon-oxide-based materials as negative active materials for lithium ion batteries, it is essential to compensate for the loss of lithium occurring during the initial charging process in advance. call it

As an essential element in the pre-lithiation process, an appropriate amount of lithium should be pre-lithiated, and pre-lithiation should be performed uniformly in the entire area. If the total lithium is insufficient compared to the quantity, the effect of the initial irreversible prevention is insignificant, and if the total lithium is excessively compared to the quantity, excess lithium is plated on the negative electrode during battery operation, which may cause safety problems such as overcharging. Since this problem may appear even in the local non-uniformity of pre-lithiation, quantitative and uniformity are very important requirements for pre-lithiation.

Therefore, it is urgent to develop a technology for a method for prelithiation of an anode active material that can solve this problem.

In this embodiment, in the prelithiation of the negative electrode, it is possible to provide an anode in which lithium is uniformly compensated in the entire region and the amount of compensated lithium is precisely controlled.

In addition, in the pre-lithiation process of the anode, by using the plating solution composition used to easily and effectively form a film containing fluorine on the surface of the anode active material layer during the pre-lithiation process to provide a lithium secondary battery with dramatically improved electrochemical performance. can

In the negative electrode for a lithium secondary battery according to an embodiment, a film containing fluorine (F) is positioned on a surface of a current collector, a negative active material layer positioned on the current collector, and the negative active material layer, and the negative electrode active material layer is prelithiated (pre-lithiation), and the film may contain 0.3 wt% or more of fluorine (F) based on the entire film.

A method of manufacturing a negative electrode for a lithium secondary battery according to another embodiment includes the steps of preparing a first electrolyte in which a lithium salt is dissolved, preparing a second electrolyte in which an additive containing fluorine is added to the first electrolyte, the first 2 Preparing a negative electrode including a negative electrode active material layer and a lithium electrode opposed thereto, impregnated in an electrolyte solution, and applying a current to the negative electrode and the lithium electrode to pre-lithiation the negative electrode And, the pre-lithiation of the negative electrode may include forming a film containing fluorine (F) on the negative electrode active material layer.

A lithium secondary battery according to another embodiment may include a positive electrode, a negative electrode according to an embodiment, and an electrolyte.

According to an embodiment, the initial irreversible problem can be effectively solved by using prelithiation.

In addition, by applying the negative electrode in which a film containing fluorine is formed on the surface of the prelithiated negative electrode active material layer to the lithium secondary battery, side reactions between the electrolyte and the negative electrode can be effectively blocked.

In addition, since such a negative electrode has high flexibility, it is possible to significantly improve the lifespan of the lithium secondary battery by suppressing dendrite growth by uniform detachment and adhesion of lithium from the surface of the negative electrode due to less film breakage.

1 is a schematic diagram of an apparatus for prelithiation according to an embodiment of the present invention.
2A shows the surface shape of a prelithiated negative electrode according to Example 3. FIG.
Figure 2b shows the results showing the EDS component analysis peak with respect to the area of the surface shown in Figure 2a.
3 shows the results of manufacturing a coin cell and evaluating charging and discharging characteristics by using a pre-lithiated negative electrode material according to each Example and Comparative Example.
4 shows the Coulombic Efficiency calculated from the charging and discharging capacities at the time of charging/discharging performance evaluation.
5 shows the results of high-speed long-term charging and discharging characteristics evaluation using the coin cell for which the evaluation of charging and discharging characteristics of FIG. 3 has been completed.

Terms such as first, second and third are used to describe, but are not limited to, various parts, components, regions, layers and/or sections. These terms are used only to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, a first part, component, region, layer or section described below may be referred to as a second part, component, region, layer or section without departing from the scope of the present invention.

The terminology used herein is for the purpose of referring to specific embodiments only, and is not intended to limit the invention. As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite. The meaning of "comprising," as used herein, specifies a particular characteristic, region, integer, step, operation, element and/or component, and includes the presence or absence of another characteristic, region, integer, step, operation, element and/or component. It does not exclude additions.

When a part is referred to as being “on” or “on” another part, it may be directly on or on the other part, or the other part may be involved in between. In contrast, when a part refers to being "directly above" another part, the other part is not interposed therebetween.

Although not defined otherwise, all terms including technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Commonly used terms defined in the dictionary are additionally interpreted as having a meaning consistent with the related technical literature and the presently disclosed content, and unless defined, they are not interpreted in an ideal or very formal meaning.

In addition, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In the negative electrode for a lithium secondary battery according to an embodiment, a film containing fluorine (F) is positioned on a surface of a current collector, a negative active material layer positioned on the current collector, and the negative active material layer, and the negative electrode active material layer is prelithiated (pre-lithiation), the film may contain 0.5 wt% or more of fluorine (F) based on the entire film.

According to the negative electrode for a lithium secondary battery according to the present embodiment, since the film containing fluorine is already located on the surface of the negative active material layer before the battery assembly step, various problems that may occur when such a film is formed during battery operation can be prevented in

Specifically, when an excessive amount of lithium salt is used in the electrolyte to form a film containing fluorine on the surface of the negative active material layer during battery operation, the concentration of the electrolyte increases and lithium ion conductivity decreases.

In addition, when FEC is used in excess as an electrolyte additive to form a film containing fluorine on the surface of the anode active material layer during battery operation, the generation of hydrogen fluoride (HF) during battery operation is further accelerated, which prevents the dissolution of the cathode active material component. There is a problem of reducing the capacity and lifespan of the battery by inducing it.

However, when the negative electrode for a lithium secondary battery according to an embodiment is applied, a lithium secondary battery having excellent electrochemical performance while preventing the above-described problems from occurring can be realized.

The negative electrode may have a structure in which the negative electrode active material layer is positioned on both surfaces of the current collector.

The current collector is for electrical connection within the battery.

The current collector may have the form of a thin film, but is not limited thereto, and for example, a mesh, a foam, a rod, a wire, and a wire, It may have the form of a sheet in which fibers) are woven.

As the material of the current collector, a material having electrical conductivity and limited reaction with lithium may be used. As the material of the current collector, for example, copper, nickel, titanium, stainless steel, gold, platinum, silver, tantalum, ruthenium, and alloys thereof, carbon, conductive polymer, non-conductive polymer coated with a conductive layer Any one of the composite fibers or a combination thereof may be used.

If the thickness of the current collector is thick, the weight of the battery increases and the energy density of the battery is lowered, and if the thickness of the current collector is thin, there is a risk of overheating damage during high current operation, and may be damaged by tension during the battery manufacturing process. Accordingly, the thickness of the current collector may be in the range of 1 μm to 50 μm.

The thickness of the negative active material layer may be 10 to 200㎛. If the anode active material layer is too thick, it is difficult to see a sufficient charging effect compared to an increase in the thickness of the battery, and peeling may occur. When it is too thin, there exists a possibility that a battery characteristic may fall.

The anode active material in the anode active material layer may include, for example, at least one of a silicon-based compound, a silicon oxide-based compound, a carbon-based compound, and a combination thereof.

Based on the entire negative active material layer, the weight ratio of carbon (C) and silicon (Si) may be in the range of 95:5 to 60:40, and more specifically, in the range of 90:10 to 70:30. When the weight ratio of carbon and silicon based on the entire anode active material layer satisfies the above range, it is possible to obtain the effect of increasing the capacity by the high-capacity silicon-based and silicon-oxide-based material, as well as during charging and discharging due to excessive use of silicon. Volume expansion can be suppressed.

In this embodiment, the anode active material layer is pre-lithiated. In this case, the lithium content at any point in the thickness direction of the negative electrode active material may be within the range of the minimum and maximum values of the lithium content within 20 length % from the surface portion of the negative electrode active material layer in the thickness direction. More specifically, the distribution of lithium from the surface portion to the lower portion of the current collector in the thickness direction of the negative electrode may be uniform.

A film containing fluorine (F) may be positioned on the surface of the anode active material layer.

The film may contain 0.3 wt% or more of fluorine (F) based on the entire film. More specifically, the film may include 0.5 to 2.8 wt% or 0.6 wt% to 2.7 wt% of fluorine based on the entire film.

Based on the entire film, the weight ratio between the sum of carbon and silicon and fluorine may be in the range of 99.5:0.5 to 97.0:3.0, and more specifically, in the range of 99.3:0.7 to 97.1 to 2.9. When the weight ratio between the sum of carbon and silicon and fluorine satisfies the above range, an effect of improving the lifespan during battery operation can be obtained due to the role of an appropriate amount of SEI as a protective film, and resistance increase due to SEI that may occur when excess LiF is generated can prevent

The thickness of the film may be, for example, 2 nm to 2 μm, more specifically, 10 nm to 500 nm.

If the thickness of the film located on the surface of the negative electrode is too thick, lithium ion conductivity may be lowered and interfacial resistance may be increased, so that charging and discharging characteristics may be deteriorated when a battery is applied. In addition, if the thickness of the film is too thin, the film may be easily lost in the process of applying the negative electrode according to the embodiment to the battery.

In this case, the film may include, for example, LiF, LiFSI, Li ₂ CO ₃ , LiOH, Li ₂ O, and the like.

As in this embodiment, when a negative electrode having a film containing fluorine on the surface of the negative electrode active material is applied to a lithium secondary battery, a side reaction between the electrolyte and the prelithiated negative electrode can be blocked. In addition, it is possible to improve the charge/discharge life of the lithium secondary battery by suppressing dendrite growth by uniformly desorption and adhesion of lithium from the surface of the anode.

In another embodiment of the present invention, preparing a first electrolyte in which a lithium salt is dissolved, preparing a second electrolyte in which an additive containing fluorine is added to the first electrolyte, impregnated in the second electrolyte, Preparing a negative electrode comprising a negative electrode active material layer and a lithium electrode facing the negative electrode, and applying a current to the negative electrode and the lithium electrode to pre-lithiation the negative electrode, comprising the steps of: The pre-lithiation may include forming a film including fluorine (F) on the anode active material layer.

First, a first electrolyte in which a lithium salt is dissolved is prepared.

The lithium salt includes, for example, at least one from the group consisting of _{LiFSI, LiTFSI, LiBF 4} , LiPF ₆ , LiAsF ₆ , LiClO ₄ and LiN(SO ₂ CF ₃ ) _{2 .} In addition, the concentration of the lithium salt in the first electrolyte may be in the range of 0.1M to 2.0M.

A step of preparing a second electrolyte in which an additive containing fluorine is added to the first electrolyte is performed.

The additive containing the fluorine is, for example, fluoroethylene carbonate (Fuoroethylene carbonate, FEC, F(C ₂ H ₃ O ₂ )CO), hydrofluoroether (Hydro Fluoro Ether, HFE, C4F ₉ OC ₂ H ₅ ), tetrafluoropropanol (Tetrafluoro Propanol, TFP, C ₃ H ₄ F ₄ O) and octafluoropentanol (Octafluoro Pentanol, OFP, C ₅ H ₄ F ₈ O) may contain at least one member from the group consisting of have.

The content of the additive containing fluorine may be in the range of 1 wt% to 40 wt% based on 100 wt% of the first electrolyte, and more specifically 1.5 wt% to 35 wt% or 2 wt% to 30 wt% can be a range. When the content of the additive containing fluorine is less than 1% by weight, it is insufficient to effectively and sufficiently form a LiF film, so that the effect of improving capacity and life is low. In addition, when the content of the additive containing fluorine exceeds 40% by weight, the viscosity of the second electrolyte is too high, so that the ionic conductivity of the second electrolyte is lowered, so that the total lithiation efficiency is lowered. cause a decrease in capacity.

Thereafter, preparing a negative electrode including a negative electrode active material layer and a lithium electrode opposed thereto, impregnated in the second electrolyte, and applying a current to the negative electrode and the lithium electrode to pre-lithiation the negative electrode ) to perform the steps.

1 schematically shows an apparatus for prelithiation according to an embodiment of the present invention.

In the prelithiation device as shown in FIG. 1 , a flat lithium electrode may be applied to maintain a constant distance between the surface of the anode active material layer and the lithium electrode (eg, a lithium metal electrode).

The smaller the distance between the surface of the anode active material layer and the lithium electrode, the more uniform current application can be obtained. In addition to causing a difference in the degree of pre-lithiation, pre-lithiation may occur only in the center of the surface of the anode active material layer.

To prevent this, an additional separator may be inserted between the anode active material layer and the lithium electrode to fundamentally prevent the contact. Therefore, whether to insert the separator can be freely selected according to the need.

More specifically, the gap between the negative electrode and the lithium electrode may be greater than 0 and less than or equal to 1,500 μm. More specifically, it may be 10 to 1,500 μm. More specifically, it may be 10 to 1,000 μm.

The current density may be 0.1 to 100 mA/cm ² based on the area of the lithium electrode. When the current density is increased, the total lithiation rate is increased, so the productivity is increased, but there is a problem in that the performance of the anode is lowered due to the deterioration of the uniformity and the properties of the film. Accordingly, the current density is preferably within the above range. In addition, the correlation between the current density and the interval is replaced with the above description.

An area of the lithium electrode may be ^{25 to 1,000 cm 2 .}

A separator may be positioned between the negative electrode and the lithium electrode. As described above, in this case, the gap between the negative electrode and the lithium electrode may be uniformly maintained.

In another embodiment of the present invention, there is provided a lithium secondary battery including a positive electrode, a negative electrode, and an electrolyte positioned between the positive electrode and the negative electrode.

The lithium secondary battery may have an initial coulombic efficiency of 85 to 100%. This can be achieved by the pre-lithiation process described above.

Since the negative electrode is the negative electrode of the above-described embodiment, a detailed description thereof will be omitted as the same as described above.

The positive electrode includes a positive electrode active material, and a compound capable of reversible intercalation and deintercalation of lithium (lithiated intercalation compound) may be used as the positive electrode active material, for example, cobalt, manganese, At least one of a complex oxide of lithium and a metal selected from nickel and combinations thereof may be used. Characteristics of such a positive active material and a positive electrode including the same are generally known in the art. Therefore, a detailed description will be omitted.

The electrolyte includes a non-aqueous organic solvent and a lithium salt.

The non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move.

The lithium salt is dissolved in an organic solvent, serves as a source of lithium ions in the battery, enables basic lithium secondary battery operation, and promotes movement of lithium ions between the positive electrode and the negative electrode.

Depending on the type of the lithium secondary battery, a separator may exist between the positive electrode and the negative electrode. As such a separator, polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof may be used, a polyethylene/polypropylene two-layer separator, a polyethylene/polypropylene/polyethylene three-layer separator, and polypropylene/polyethylene/poly It goes without saying that a mixed multilayer film such as a propylene three-layer separator or the like can be used.

Lithium secondary batteries can be classified into lithium ion batteries, lithium ion polymer batteries, and lithium polymer batteries depending on the type of separator and electrolyte used, and can be classified into cylindrical, prismatic, coin-type, pouch-type, etc. according to the shape. According to the size, it can be divided into a bulk type and a thin film type. Since the structure and manufacturing method of these batteries are well known in the art, a detailed description thereof will be omitted.

Hereinafter, embodiments of the present invention will be described in detail. However, this is provided as an example, and the present invention is not limited thereto, and the present invention is only defined by the scope of the claims to be described later.

(Example 1)

_{The electrolyte used for prelithiation was prepared by dissolving 1M concentration of LiPF 6} in a solvent of EC/EMC=30/70 to prepare a first electrolyte.

Next, a second electrolyte was prepared by adding 2% by weight of FEC, a fluorine-containing additive, to the first electrolyte based on 100% by weight of the first electrolyte.

Next, pre-lithiation was performed on the anode active material layer using a pre-lithiation apparatus as shown in FIG. 1 . Specifically, an anode and a lithium metal electrode, which is a lithium source opposed thereto, impregnated in the second electrolyte, were prepared.

As a lithium source, a lithium metal plate with a purity of 99.9% and a thickness of 500 μm was used by pressing on a copper current collector plate (Cu plate).

On the other hand, the negative electrode is a composite negative electrode material composed of 30% silicon oxide-based material and 70% graphite in a weight ratio on a flat 10㎛ thick copper foil (Cu foil), 70㎛ each of the negative electrode active material layers are applied on both sides of the copper thin plate. The negative electrode was used. The used negative electrode has a capacity of 700 mAh/g, and by passing a current of 2 mA/cm 2 for 1 hour to prelithiate the negative electrode, lithium corresponding to a capacity of 2.0 mAh/cm 2 is separated from lithium metal into ions, and the anode active material layer to be inserted.

The gap between the lithium metal electrode and the anode active material layer was maintained at 10 μm, and a separator having a thickness of 10 μm was inserted to prevent direct contact between the lithium metal and the anode active material layer over the entire area.

In this state, using a power supply, current was applied to the lithium metal electrode and the current collector as (+) and (-) electrodes, respectively, to separate lithium ions from the lithium metal and insert them into the anode material.

(Example 2)

Pre-lithiation was performed in the same manner as in Example 1, except that 15 wt% of the fluorine-containing additive FEC was added based on 100 wt% of the first electrolyte to prepare a second electrolyte.

(Example 3)

Pre-lithiation was performed in the same manner as in Example 1, except that 30% by weight of the fluorine-containing additive, FEC, was added based on 100% by weight of the first electrolyte to prepare a second electrolyte.

(Comparative Example 1)

Pre-lithiation was performed in the same manner as in Example 1, except that the second electrolyte was not prepared by adding a fluorine-containing additive to the first electrolyte. That is, all-lithiation was performed using the first electrolyte.

(Comparative Example 2)

Pre-lithiation was performed in the same manner as in Example 1, except that 50% by weight of FEC, a fluorine-containing additive, was added based on 100% by weight of the first electrolyte to prepare a second electrolyte.

Experimental example

FIG. 2a shows the surface shape of the prelithiated negative electrode according to Example 3, and FIG. 2b shows the results showing the EDS component analysis peak with respect to the surface area shown in FIG. 2a. Table 1 shows the ratio of the fluorine component of the film positioned on the surface of the negative electrode active material layer according to the amount of the fluorine-containing additive added using the above analysis method.

division FEC added amount ?t amount (wt%) for each negative electrode surface component Fluorine weight ratio (%)
(C+Si ) : F C Si F Comparative Example 1 0% 68.62 18.04 0.26 99.7 : 0.3 Example 1 2% 69.02 18.48 0.65 99.3 : 0.7 Example 2 15% 69.91 17.6 1.76 98.0 : 2.0 Example 3 30% 69.65 16.9 2.62 97.1 : 2.9 Comparative Example 2 50% 67.11 18.67 2.85 96.8:3.2

First, referring to FIGS. 2A and 2B , it can be confirmed that the fluorine component is detected on the surface of the prelithiated anode active material layer.

Next, referring to Table 1, it can be seen that when a fluorine-containing additive (FEC) is used, the fluorine component is clearly observed on the surface of the anode active material layer, and the ratio of the fluorine component in the surface film of the anode active material layer increases as the amount of addition increases. can That is, it shows that the amount of the coating component including fluorine positioned on the surface of the anode active material layer is directly affected by the amount of the fluorine-containing additive used in the plating electrolyte.

3 shows the results of manufacturing a coin cell and evaluating charging and discharging characteristics using a pre-lithiated anode material according to each of Examples and Comparative Examples.

The coin cell used in the evaluation had a size of 2032 type, and a Li _1+x (Ni _y Mn _z Co _w ) _1-x O ₂ series material was used as the cathode active material.

The charging condition was a constant current-constant voltage mixed mode, the constant current was 0.1C, the constant voltage was 4.2V, and the cutoff current was set to 0.05C. On the other hand, the discharge condition is a constant current mode, the constant current is 0.1C, and the cutoff voltage is set to 2.5V.

Referring to FIG. 3 , when the negative electrodes prepared according to Examples 1 to 3 are applied, high charging and discharging capacities are shown, thereby showing the effect of increasing the capacity according to the prelithiation of the negative electrode active material layer. In addition, it can be confirmed that the capacity retention rate is excellent compared to Comparative Examples 1 and 2.

4 shows the Coulombic Efficiency calculated from the charging and discharging capacities at the time of charging/discharging performance evaluation.

Referring to FIG. 4 , when the negative electrode prepared according to Examples 1 to 3 is applied, a high initial Coulombic Efficiency (ICE) of 89.4 to 90.7% in the first cycle, which is the first charge/discharge process, is obtained. show This is because the decrease in activated lithium due to the initial irreversible reaction was greatly alleviated by the effect of lithium compensated in advance through prelithiation. Considering that the initial coulombic efficiency when a silicon oxide-based material not subjected to pre-lithiation is used for the anode active material layer is about 70%, it can be seen that the effect of pre-lithiation is sufficiently exhibited in the anodes of Examples 1 to 3 have.

On the other hand, even when the negative electrode prepared according to Comparative Example 1 and Comparative Example 2 is applied, the initial Coulombic efficiencies are 88.2% and 89.8%, respectively, which is higher than that in the case where prelithiation is not performed. However, it can be seen that, in the charging/discharging process after the second time, a relatively low coulombic efficiency is exhibited as compared with Examples 1 to 3.

5 shows the results of high-speed long-term charging and discharging characteristics evaluation using the coin cell for which the evaluation of charging and discharging characteristics of FIG. 3 has been completed.

The charging conditions for high-speed long-term charge/discharge evaluation were constant current-constant voltage mixed mode, constant current was 1.0C, constant voltage was 4.2V, and cut-off current was set to 0.05C. On the other hand, the discharge condition was a constant current mode, a constant current of 1.0C, and a cut-off voltage of 2.5V.

Referring to FIG. 5 , when the negative electrode prepared according to Examples 1 to 3 is applied, a high capacity is very stably maintained, whereas when the negative electrode prepared according to Comparative Examples 1 to 2 is applied, Examples 1 to It can be seen that the capacity is low compared to 3 and the decrease in capacity is also large.

Therefore, from this embodiment, the negative electrode active material, particularly the negative electrode active material layer containing the silicon-based material and silicon oxide-based material having an effective capacity of 10 times or more than that of the carbon-based material, the negative electrode active material layer is formed using an electrochemical method, , by adjusting the amount of the plating solution additive used in the prelithiation process, it is possible to effectively form a film containing fluorine on the surface of the negative electrode active material layer.

In addition, when all-lithiation is performed in the same manner as in the embodiment, the initial irreversible problem, which is the basic purpose of all-lithiation, is solved, so that high capacity and high initial coulombic efficiency can be obtained. In addition, as the fluorine-containing film is formed on the surface of the negative electrode active material, when the negative electrode of one embodiment is applied, the charge and discharge life of the lithium secondary battery can be greatly increased. This is considered to be because the fluorine-containing film formed on the surface of the anode active material layer effectively blocks a side reaction between the electrolyte and the anode. In addition, since the negative electrode of one embodiment has high flexibility, there is less film breakage during the charging and discharging process, so that dendrite growth is suppressed by uniform detachment and adhesion of lithium from the surface of the negative electrode, so that a lithium secondary battery with a more improved charge and discharge life can be implemented. have.

The present invention is not limited to the above embodiments, but can be manufactured in a variety of different forms, and those of ordinary skill in the art to which the present invention pertains can take other specific forms without changing the technical spirit or essential features of the present invention. It will be understood that it can be implemented as Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (15)

current collector;
a negative active material layer positioned on the current collector; and
A film containing fluorine (F) is positioned on the surface of the anode active material layer,
The anode active material layer is pre-lithiated,
The film is a negative electrode for a lithium secondary battery comprising 0.3% by weight or more of fluorine (F) based on the entire film. According to claim 1,
The anode active material in the anode active material layer,
A negative electrode for a lithium secondary battery comprising at least one of a silicon-based compound, a silicon oxide-based compound, a carbon-based compound, and a combination thereof. 3. The method of claim 2,
Based on the entire anode active material layer,
A negative electrode for a lithium secondary battery wherein the weight ratio of carbon (C) and silicon (Si) is 95:5 to 60:40. According to claim 1,
The film is
A negative electrode for a lithium secondary battery comprising fluorine (F) in an amount of 0.5 to 2.8 wt% based on the entire film. According to claim 1,
Based on the entire film,
A negative electrode for a lithium secondary battery in which the weight ratio between the sum of carbon (C) and silicon (Si) and fluorine (F) is 99.5:0.5 to 97.0:3.0. According to claim 1,
The content of lithium at any point with respect to the entire thickness direction of the negative active material layer is,
A negative electrode for a lithium secondary battery that is a value within a range of a minimum value and a maximum value of the lithium content within 20% by length from the surface portion of the negative electrode active material layer in the thickness direction. According to claim 1,
The thickness of the negative active material layer is in the range of 10 to 200㎛ a negative electrode for a lithium secondary battery. Preparing a first electrolyte solution in which the lithium salt is dissolved;
preparing a second electrolyte in which an additive containing fluorine is added to the first electrolyte;
preparing a negative electrode including a negative electrode active material layer and a lithium electrode facing the negative electrode impregnated in the second electrolyte; and
pre-lithiation of the negative electrode by applying a current to the negative electrode and the lithium electrode;
including,
The pre-lithiation of the negative electrode includes forming a film containing fluorine (F) on the negative electrode active material layer. 9. The method of claim 8,
The lithium salt includes at least one from the group consisting of LiFSI, LiTFSI, LiBF4, LiPF ₆ , LiAsF ₆ , LiClO ₄ and LiN(SO ₂ CF ₃ ) ₂ , and the concentration of the lithium salt in the first electrolyte is 0.1 A method of manufacturing a negative electrode for a lithium secondary battery in the range of M to 2.0M. 9. The method of claim 8,
The additive containing the fluorine is, fluoroethylene carbonate (Fuoroethylene carbonate, FEC, F(C ₂ H ₃ O ₂ )CO), hydrofluoroether (Hydro Fluoro Ether, HFE, C4F ₉ OC ₂ H ₅ ), tetrafluoro Propanol (Tetrafluoro Propanol, TFP, C ₃ H ₄ F ₄ O) and octafluoropentanol (Octafluoro Pentanol, OFP, C ₅ H ₄ F ₈ O) of a negative electrode for a lithium secondary battery containing at least one from the group consisting of manufacturing method. 9. The method of claim 8,
The content of the additive containing fluorine is,
A method of manufacturing a negative electrode for a lithium secondary battery in the range of 1 to 40% by weight based on 100% by weight of the first electrolyte. 9. The method of claim 8,
The process of applying the current is
A method of manufacturing a negative electrode for a lithium secondary battery in which a current of 0.1 mA/cm 2 to 10 mA/cm 2 is applied for 0.1 hour to 100 hours. 9. The method of claim 8,
The gap between the negative electrode and the lithium electrode is greater than 0 and 1,500 μm or less. anode;
The negative electrode of any one of claims 1 to 7; and
Electrolyte positioned between the anode and cathode
A lithium secondary battery comprising a. 15. The method of claim 14,
The lithium secondary battery is a lithium secondary battery having an initial coulombic efficiency of 85 to 100%.

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