JP2005190902A - Manufacturing method for lithium precursor battery and lithium secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium precursor battery having a large battery capacity and an excellent cycle property. <P>SOLUTION: In the lithium precursor battery or the lithium secondary battery provided with a positive electrode, a negative electrode comprising a thin film layer of an amorphous material or a microcrystal consisting essentially of silicon and a nonaqueous electrolyte, the negative electrode includes an outermost layer 52 not containing lithium and a layer 51 containing lithium intervening between a negative electrode current collector and the outermost layer. The amount of lithium contained in the layer containing lithium is 1 to 50 per 100 silicon atoms. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an improvement of a lithium secondary battery, and more particularly to an improvement of a negative electrode for a lithium secondary battery.

  A lithium secondary battery using a carbon material that occludes and releases lithium ions as a negative electrode active material is free of dendritic (dendritic) lithium deposition because lithium does not exist in a metallic state, and has excellent safety and cycle life. Because of its high energy density and high capacity, it is widely used as a driving power source for mobile information terminals and the like.

  In recent years, however, mobile information terminals have become more multifunctional and sophisticated, and power consumption has increased accordingly. For this reason, a battery having a higher capacity than before has been demanded.

  Against this background, silicon having lithium storage capacity and having a larger amount of lithium storage than carbon materials has attracted attention as an active material for a negative electrode that can replace carbon materials. However, since silicon has a large volume fluctuation due to insertion and extraction of lithium and a short cycle life, there has been a problem that performance sufficient for use as a practical battery cannot be obtained.

  Various proposals have been made as means for solving this problem. For example, Patent Document 1 proposes a technique using amorphous silicon or microcrystalline silicon.

JP 2002-83594 A (Abstract)

  In this technique, for example, an active material layer mainly composed of amorphous silicon or microcrystalline silicon is deposited on a roughened current collector, and a columnar active material layer is formed by charging and discharging. According to this means, the high capacity negative electrode having excellent cycle performance can be obtained by absorbing the expansion and contraction of the active material and preventing the active material from falling off the electrode.

  However, even with this technique, the initial charge / discharge efficiency does not reach 100%, and the electrode plate gradually expands during the charge / discharge cycle, which causes cycle deterioration.

  On the other hand, techniques for improving initial characteristics by adding lithium in advance to a negative electrode including a metal alloyed with lithium have been proposed (Patent Documents 2 to 4).

JP 2003-217574 A (Abstract) JP-A-7-326345 (abstract) JP-A-4-255667 (abstract)

  However, in each of the above technologies, metallic lithium or a lithium alloy is used. However, metallic lithium and the like have high reactivity, so that handling is bad, and when an oxide film is formed on the surface by reacting with air, conductivity is reduced. There is a problem in that initial characteristics and cycle characteristics are degraded due to a significant decrease.

  The inventors have conducted intensive research to solve the above-mentioned problems. As a result, the alloy layer containing lithium and silicon was used, and the lithium-silicon alloy layer was used as the negative electrode current collector and lithium. By providing an outermost layer not included and interposing between the outermost layer, lithium can be included in the negative electrode while reliably suppressing the reaction between air and lithium, thereby improving initial characteristics and cycle characteristics. I found.

  The present invention has been completed on the basis of the above knowledge, and has a large battery capacity and a lithium precursor battery that is a predecessor of a lithium secondary battery excellent in cycle characteristics, and a lithium secondary battery that has undergone a lithium precursor battery. An object is to provide a method of manufacturing a battery.

  A lithium precursor battery for solving the above problems is a lithium precursor battery comprising a positive electrode, a negative electrode composed of an amorphous or microcrystalline thin film layer containing silicon as a main component, and a non-aqueous electrolyte. The negative electrode includes an outermost layer that does not include lithium, and a layer that includes lithium interposed between the negative electrode current collector and the outermost layer.

  Here, the “lithium precursor battery” means a battery after battery assembly in which charging / discharging has never been performed.

  Further, “having silicon as a main component” means that when the amount of silicon atoms is 100, the total amount of other elements is 50 or less.

  "Lithium is included" means that the silicon layer is intentionally included with lithium, and "does not include lithium" means that the silicon layer is not intentionally included with lithium. Means. Therefore, the “outermost layer not containing lithium” contains a very small amount of lithium as an impurity derived from the silicon raw material, and the outermost layer intentionally does not contain lithium in the silicon layer. Corresponds to “the outermost layer not containing lithium”.

  Further, “amorphous or microcrystalline” means amorphous and microcrystal having a crystallite size of 100 nm or less. The determination of whether or not it is amorphous and the measurement of the crystallite size in the microcrystalline thin film can be performed by applying the presence or absence of a peak in the X-ray diffraction spectrum and the half-width of the peak to the Scherrer equation. it can.

  In the invention of the lithium precursor battery, the lithium-containing layer may be directly formed on the negative electrode current collector.

  Moreover, when the amount of lithium contained in the layer containing lithium is 100, the structure may be 1 or more and 50 or less.

  The arithmetic mean roughness Ra of the negative electrode current collector surface may be 0.1 μm or more. The arithmetic average roughness Ra is defined in Japanese Industrial Standard (JIS B 0601-1994). The arithmetic average roughness Ra can be measured by, for example, a stylus type surface roughness meter.

  Further, the lithium-containing layer may have a thickness of 0.5 μm or more.

  The outermost layer may have a thickness of 0.5 μm or more.

  The negative electrode may include a different element other than silicon and lithium. Different elements (added to amorphous or microcrystalline thin film layers containing silicon as a main component (layers containing lithium, outermost layer, etc.)) include carbon, aluminum, silicon, phosphorus, zinc, gallium, Germanium, arsenic, cadmium, indium, tin, antimony, mercury, thallium, lead, bismuth, specifically scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium And at least one element selected from molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, lanthanoid elements, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, mercury, and the like. Of these, cobalt is preferably used.

  The present invention according to a method for manufacturing a lithium secondary battery for solving the above-described problem includes a negative electrode manufacturing step of depositing an amorphous or microcrystalline thin film layer mainly composed of silicon on a negative electrode current collector. In the method for manufacturing a lithium secondary battery, the negative electrode manufacturing step includes a first step of manufacturing a layer containing lithium, and a second step of manufacturing an outermost layer not containing lithium after the first step. It is characterized by that.

  Here, the meanings of “silicon-based”, “amorphous or microcrystalline”, “layer containing lithium”, and “outermost layer not containing lithium” in the invention relating to the lithium precursor battery Same as the case.

  In the method for producing a lithium secondary battery, the first step may be a step in which a layer containing silicon is directly formed on the negative electrode current collector.

  Further, the second step may be performed immediately after the first step.

  Moreover, it can be set as the structure whose arithmetic mean roughness Ra of the collector surface of the said negative electrode is 0.1 micrometer or more.

  Further, the step of producing the layer containing lithium and the step of producing the outermost layer may be a method in which a raw material is supplied and deposited in a vacuum.

In addition, a configuration in which the raw material is supplied and deposited in the vacuum may be either a vapor deposition method or a sputtering method.

  A layer containing lithium in silicon reacts violently when it comes into contact with air, but according to the method for producing a lithium secondary battery of the present invention, the layer containing lithium is covered with the outermost layer not containing lithium. There is no contact. . For this reason, the handleability is not lowered, and lithium can be previously contained in the negative electrode. In the lithium precursor battery having this configuration, since lithium is smoothly inserted into the entire negative electrode by the first charge / discharge, a lithium secondary battery excellent in initial charge / discharge characteristics and cycle characteristics can be easily realized.

  In addition, the volume of silicon greatly fluctuates due to occlusion and desorption of lithium ions associated with charge / discharge, but when the lithium-containing layer is directly formed on the negative electrode current collector, the lithium-containing layer is in a state of being charged in advance. Therefore, the stress between the active material and the current collector due to the expansion / contraction of the active material accompanying charge / discharge can be reduced. Thereby, peeling of the active material from the current collector due to charge / discharge is suppressed, and as a result, the cycle characteristics are remarkably improved.

  Further, it is necessary to appropriately change the amount of lithium added depending on the amount of active material at the counter electrode, the battery configuration, etc. However, if the amount added is too small, the effect of the present invention is hardly obtained, while the amount of lithium is excessively large. If it is, the cycle characteristics are not sufficiently improved. Therefore, when the amount of silicon atoms is 100, the amount of lithium atoms is preferably 1 or more and 50 or less. More preferably, it is 5 or more and 30 or less, and more preferably 10 or more and 20 or less.

  Moreover, when the uneven structure is formed on the surface of the negative electrode current collector, the columnar structure 53 mainly composed of lithium-silicon shown in FIG. 5 is formed by charge and discharge. When this columnar structure is formed, desorption from the current collector of the active material due to expansion and contraction of the negative electrode accompanying charge / discharge is remarkably suppressed. Therefore, cycle characteristics are further improved. Further, when the arithmetic average roughness Ra of the concavo-convex structure is 0.1 μm or more, this effect is sufficiently exhibited.

  In addition, when the layer thickness of the layer containing lithium is 0.5 μm or more, a sufficient amount of lithium to be previously contained in the negative electrode can be secured, and as a result, cycle deterioration is further reduced.

  The outermost layer only needs to be capable of preventing the oxidation of lithium, and theoretically, the outermost layer only needs to be thicker than oxygen penetrated by oxidation near the surface of silicon (which is expected to be several nm). From the viewpoint of production and reliability, the thickness of the outermost layer is preferably 0.5 μm or more.

  Further, when a different element is added to the amorphous or microcrystalline thin film layer containing silicon as a main component, the different element acts to improve cycle characteristics.

  Further, if the amount of the different element added is too small, the effect of improving the cycle characteristics cannot be sufficiently obtained. On the other hand, if the amount is too large, the amount of silicon as the active material is reduced and the capacity is reduced. The amount of element added is preferably in the range of 5 to 50 parts by mass and more preferably in the range of 10 to 30 parts by mass when silicon is 100 parts by mass.

  According to this invention concerning the manufacturing method of a lithium secondary battery, this invention lithium precursor battery of a 1st aspect and the lithium secondary battery formed by charging / discharging this can be manufactured efficiently.

  Here, the first step does not need to be a step of directly forming a silicon-containing layer on the negative electrode current collector, and a silicon layer (which may contain a different element) is formed on the negative electrode current collector. Thereafter, a step of forming a layer containing lithium may be used. However, in order to relieve the volume fluctuation of the active material accompanying the insertion and extraction of lithium ions and the stress on the negative electrode current collector, it is preferable to directly form a layer containing lithium on the negative electrode current collector.

  Further, the second step does not need to be performed immediately after the first step, and after the first step, a silicon layer containing a different element and not containing lithium is produced, and then silicon containing no different element or lithium is used. It may be a step of providing the outermost layer. However, even if another layer is provided between the layer containing lithium and the outermost layer, an effect such as improvement in cycle characteristics cannot be obtained. Therefore, it is easy to manufacture the second step immediately after the first step.

  Further, when the arithmetic average roughness Ra of the surface of the negative electrode current collector is 0.1 μm or more, a lithium-silicon columnar structure is formed by charging / discharging, and the active material is collected by expansion / contraction of the negative electrode accompanying charging / discharging. No longer detaches from the body. Therefore, cycle characteristics are improved. It is preferable that the arithmetic average roughness Ra of the concavo-convex structure is 0.1 μm or more because this effect can be sufficiently exhibited.

In addition, when the step of manufacturing the negative electrode is performed by a method in which a raw material is supplied and deposited in a vacuum, a layer containing lithium can be manufactured in a state where lithium does not come into contact with air.
Examples of such a method include a vapor deposition method and a sputtering method.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within a range that does not change the gist thereof.

  FIG. 1 is a perspective view of a lithium precursor battery (a lithium secondary battery after charge / discharge, hereinafter referred to as a lithium secondary battery) using a laminate outer body according to an embodiment of the present invention, and FIG. 2 is a lithium secondary battery. It is a sealing part expanded sectional view of a battery.

  In the lithium secondary battery of the present invention, as shown in FIG. 2, the negative electrode current collector 41 and the negative electrode active material layer 42, the positive electrode current collector 43 and the positive electrode active material layer 44, and both electrodes are separated in the outer package 40. A separator 45 is provided. In the exterior body 40, a nonaqueous electrolyte 46 in which a lithium salt (electrolyte salt) is dissolved in a nonaqueous solvent is accommodated.

  Further, a negative electrode tab 47 is attached to the negative electrode current collector 41 and protrudes to the outside from the sealing portion 40a. Although not shown, the positive electrode tab 48 is attached to the positive electrode current collector 43, and the structure protrudes from the sealing portion 40 a in the same manner as the negative electrode tab 47. In this way, chemical energy generated inside the battery can be taken out as electrical energy.

  Here, for example, an aluminum laminate film having a five-layer structure in which a resin layer, an adhesive layer, an aluminum layer, an adhesive layer, and a resin layer are bonded can be used as the outer package.

  Next, a battery manufacturing method for carrying out the present invention will be described.

<Preparation of negative electrode>
Copper particles were adhered to the rolled copper foil (thickness: 18 μm) by electrolytic treatment, the arithmetic average roughness Ra was set to 0.1 or more, and the negative electrode current collector 41 was produced. This was disposed so as to pass around the main roller from the supply roller of the electron beam vapor deposition apparatus shown in FIG.
Further, lithium was put in the crucible of the electron beam evaporation source 1, cobalt was put in the crucible of the electron beam evaporation source 2, and silicon was put in the crucible of the electron beam evaporation source 3.

First, the inside of the chamber is evacuated to 1 × 10 ⁻⁴ Pa or less by a vacuum pump, and the electron beam current is applied to the crucible of the electron beam evaporation source of lithium and silicon while moving the current collector from the supply roller to the take-up roller. Was adjusted to form a Li-Si layer 51 shown in FIG.
Subsequently, the silicon outermost layer 52 was formed by adjusting the electron beam current applied to the crucible of the silicon electron beam evaporation source.
Thereafter, by adjusting the electron beam current applied to the crucible of each electron beam evaporation source and changing the evaporation rate of the material in the crucible, the composition and thickness of the deposited thin film are adjusted, and the outermost layer (active material) Layer).
In addition, when a thin film is formed by electron beam evaporation, the current collector is heated and deformed, and there is a problem that the strength is lowered. Therefore, the current collector is cooled by circulating water through the main roller. . However, the cooling method is not limited to this.

  The obtained thin film was cut into a size of 2.5 × 2.5 cm together with the current collector, and a negative electrode tab 47 was attached to complete the negative electrode.

Note that, in addition to the vapor deposition method, the sputtering method can be manufactured by substantially the same process. The difference between the vapor deposition method and the sputtering method will be described below.
In the vapor deposition method, the material is evaporated and deposited on the substrate by applying an electron beam, whereas in the sputtering method, a high frequency or current is applied and the material is scattered by applying Ar plasma to deposit the material on the substrate.

<Preparation of positive electrode>
90 parts by mass of lithium cobaltate, 5 parts by mass of a conductive agent made of artificial graphite, 5 parts by mass of a binder made of polytetrafluoroethylene, and N-methyl-2-pyrrolidone (NMP) are mixed to obtain an active material A slurry was obtained.

  This active material slurry was applied to a 2 × 2 cm region of a positive electrode current collector 43 made of an aluminum foil having a thickness of 18 μm with a doctor blade and then dried to remove the organic solvent necessary for the preparation of the slurry. Subsequently, the positive electrode tab 48 was attached to the active material non-application part of this electrode plate, and the positive electrode was produced.

<Preparation of electrolyte>
LiPF ₆ as an electrolyte salt was dissolved to 1 M (mol / liter) in a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 3: 7 to prepare an electrolytic solution.

<Production of electrode body>
The positive and negative electrodes were overlapped with a separator made of a microporous film (thickness: 0.025 mm) made of an olefin resin in between, and the center lines in the width direction of the electrode plates were aligned to produce an electrode body.

  A sheet-like laminate material having a five-layer structure composed of a resin layer-adhesive layer-aluminum layer-adhesive layer-resin layer was prepared, the aluminum laminate material was folded in two, and the upper end and the left and right ends were combined. Next, the positive and negative electrode tabs 47 and 48 are inserted into the storage space so that the upper end portion of the cylindrical aluminum laminate material protrudes, and then the positive and negative electrode tabs 47 and 48 protrude. The upper end 40a and one end were welded. Next, an electrolytic solution was injected from an opening that was not yet welded (portion that becomes the sealing portion 4c after sealing), and then the sealing portion was welded. A high frequency induction welding apparatus was used for sealing each end.

  Hereinafter, the present invention will be described in more detail with reference to examples.

(Examples 1-4, Comparative Examples 1 and 2)
As shown in Table 1 below, the same as in the above embodiment, except that the thickness of the layer containing lithium, the thickness of the active material layer (outermost layer), and the conditions of other elements contained in the active material layer were changed. Thus, a battery was produced.
In Example 4, 30% by mass of cobalt is added to the outermost silicon layer.
Further, the Li ratio of the Li—Si layer is all 20 atoms of lithium with respect to 100 atoms of silicon.

  Moreover, the battery produced as mentioned above was charged / discharged under the following conditions, and the cycle characteristics were measured. The test conditions are described below, and the test results are shown in Table 1 below.

Cycle characteristic test Charging conditions: constant current 13 mA, final voltage 4.2 V, 25C
Discharge conditions: constant current 13 mA, final voltage 2.75 V, 25 ° C.
Cycle characteristics (cycle capacity retention rate) (%): (100th cycle discharge capacity / maximum discharge capacity) × 100

  From Table 1 above, in Examples 1 to 4 in which a layer containing lithium was formed between the outermost layer and the negative electrode current collector, the initial capacity was 5.3 to 8.6 mAh, and the capacity retention ratio was 46 to 78. On the other hand, in Comparative Example 1 in which the layer containing lithium was not formed, it was found that the initial capacity was 3.8 mAh and the capacity retention rate was 32%.

  This is presumably because, in Comparative Example 1, lithium was not added to the negative electrode in advance, so that the amount of lithium trapped in the negative electrode and no longer contributing to charge / discharge increased.

  Further, from Table 1 above, in Examples 1 to 4 in which a layer containing lithium was formed between the outermost layer and the negative electrode current collector, the initial capacity was 5.3 to 8.6 mAh, and the capacity retention ratio was 46. On the other hand, in Comparative Example 2 in which the layer containing lithium was formed as the outermost layer, it was found that the initial capacity was 1.2 mAh and the capacity retention rate was 17%.

  This is presumably because, in Comparative Example 2, lithium was added to the outermost layer, so that the outermost layer was oxidized when contacted with oxygen or the like, and the conductivity of the negative electrode was significantly reduced.

  Also, from Table 1 above, in Examples 2 to 4 where the amount of lithium was 1.0 atomic% or more, the initial capacity was 6.9 to 8.6 mAh, and the capacity retention rate was 63 to 78%. On the other hand, in Example 1 in which the amount of lithium is 0.5 atomic%, it can be seen that the initial capacity is 5.3 mAh and the capacity retention rate is 46%.

  This is presumably because Example 1 has too little lithium pre-added to the negative electrode, so that the amount of lithium in the negative electrode contributing to charge / discharge is too small.

  From Table 1 above, in Example 4 in which cobalt was added to the outermost layer, the capacity retention rate was 78%, whereas in Examples 1 to 3 in which cobalt was not added to the outermost layer. Then, it turns out that a capacity | capacitance maintenance factor has a remarkable difference with 46 to 63%.

  This is considered because Example 4 acts so that cobalt added to the negative electrode improves the cycle characteristics.

[Other matters]
In the above embodiment, the laminate outer package is used. However, it is a matter of course that various shapes such as a cylindrical shape, a coin shape, and a square shape can be used. The present invention can also be applied to a battery in which positive and negative electrodes are alternately stacked, and a battery in which a positive and negative electrode and a separator are wound.

  Further, as the positive electrode active material, one kind of compound selected from lithium-containing transition metal composite oxides, or a mixture of two or more kinds of compounds can be used. For example, lithium cobaltate, lithium nickelate, manganate Lithium, lithium ferrate, or an oxide obtained by substituting part of the transition metal contained in these oxides with another element can be used.

  In addition, as the non-aqueous solvent used for the electrolyte, a kind of compound selected from carbonates, lactones, ethers, ketones, nitriles, amides, sulfone compounds, esters, aromatic hydrocarbons, Or it can use in mixture of 2 or more types. Among these, carbonates, lactones, ethers, ketones, and nitriles are preferable, and carbonates are more preferable. Specific examples thereof include ethylene carbonate, propylene carbonate, butylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, anisole, 1,4-dioxane, 4-methyl. -2-pentanone, cyclohexanone, acetonitrile, propionitrile, dimethylformamide, sulfolane, methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, ethyl propionate and the like.

The electrolyte salt is selected from lithium salts such as LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ , LiCF ₃ SO ₃ , LiPF ₆ , LiBF ₄ , LiAsF ₆ and LiClO _4. These compounds can be used alone or in combination of two or more. The amount of electrolyte salt dissolved in the non-aqueous solvent is preferably 0.5 to 2.0 mol / liter.

  Moreover, although slurry was apply | coated with the doctor blade in said embodiment, it can also apply | coat by a die-coater and the roller coating method. Moreover, even if it uses an aluminum mesh instead of an aluminum foil, it can produce similarly.

  As is clear from the above results, according to the present invention, there is an excellent effect that a lithium secondary battery having excellent cycle characteristics and a large capacity can be provided. Therefore, industrial applicability is great.

It is a front view of the lithium secondary battery which concerns on this invention. It is a fragmentary sectional view of the lithium secondary battery which concerns on this invention. It is a conceptual diagram which shows the outline of the vapor deposition apparatus used in order to produce the lithium secondary battery which concerns on this invention. It is a cross-sectional conceptual diagram of the negative electrode of the lithium precursor battery which concerns on this invention. It is a cross-sectional conceptual diagram of the negative electrode after charging / discharging with respect to the lithium precursor battery which concerns on this invention.

Explanation of symbols

40 exterior body 41 negative electrode current collector 42 negative electrode active material layer 43 positive electrode current collector 44 positive electrode active material layer 45 separator 46 nonaqueous electrolyte 47 negative electrode tab 48 positive electrode tab 51 Si-Li layer 52 active material layer (outermost layer)
53 Lithium-silicon columnar structure

Claims (13)

In a lithium precursor battery comprising a positive electrode, a negative electrode composed of an amorphous or microcrystalline thin film layer mainly composed of silicon, and a non-aqueous electrolyte,
The negative electrode has an outermost layer that does not contain lithium,
A layer containing lithium interposed between the negative electrode current collector and the outermost layer;
A lithium precursor battery comprising: The lithium precursor battery according to claim 1,
The lithium-containing layer is formed directly on the negative electrode current collector;
The lithium precursor battery characterized by the above-mentioned. The lithium precursor battery according to claim 1 or 2,
When the amount of lithium contained in the layer containing lithium is 100, the amount of silicon atoms is 1 or more and 50 or less.
The lithium precursor battery characterized by the above-mentioned. The lithium precursor battery according to claim 1, 2, or 3,
Arithmetic mean roughness Ra of the negative electrode current collector surface is 0.1 μm or more,
The lithium precursor battery characterized by the above-mentioned. The lithium precursor battery according to claim 1, 2, 3 or 4,
The layer thickness of the layer containing lithium is 0.5 μm or more,
The lithium precursor battery characterized by the above-mentioned. The lithium precursor battery according to claim 1, 2, 3, 4 or 5,
The outermost layer has a layer thickness of 0.5 μm or more.
The lithium precursor battery characterized by the above-mentioned. The lithium precursor battery according to claim 1, 2, 3, 4, 5 or 6,
The negative electrode includes a different element other than silicon and lithium.
The lithium precursor battery characterized by the above-mentioned. In a method for producing a lithium secondary battery comprising a negative electrode preparation step of depositing an amorphous or microcrystalline thin film layer mainly composed of silicon on a negative electrode current collector,
The negative electrode manufacturing step, a first step of manufacturing a layer containing lithium,
After the first step, a second step of producing an outermost layer that does not contain lithium;
A method for producing a lithium secondary battery, comprising: In the manufacturing method of the lithium secondary battery according to claim 8,
The first step is a step of producing a layer containing silicon directly on the negative electrode current collector,
A method for producing a lithium secondary battery. In the manufacturing method of the lithium secondary battery according to claim 8 or 9,
The second step is performed immediately after the first step;
A method for producing a lithium secondary battery. In the manufacturing method of the lithium secondary battery according to claim 8, 9 or 10,
Arithmetic mean roughness Ra of the negative electrode current collector surface is 0.1 μm or more,
A method for producing a lithium secondary battery. In the manufacturing method of the lithium secondary battery according to claim 8, 9, 10 or 11,
The step of producing the negative electrode is performed by a method of supplying and depositing a raw material in a vacuum,
A method for producing a lithium secondary battery. In the manufacturing method of the lithium secondary battery according to claim 12,
The method of supplying and depositing the raw material in the vacuum is an evaporation method or a sputtering method.
A method for producing a lithium secondary battery.

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