JPH0837000A - Negative electrode, its manufacturing method, and lithium secondary battery - Google Patents

Abstract

PURPOSE:To efficiently produce a tapelike negative electrode superior in discharge capacity maintenance rate by applying a hot dip coating layer of lithium or lithium alloy on a current collection tape and forming a Li ion transmission film. CONSTITUTION:A current collection tape 1 is formed by laminating a diffusion barrier layer 12 such as nicked and a wet acceleration layer 13 such as silver and tin on a conductive support base material in this order. A hot dip coating layer 2 of lithium or/and lithium alloy is applied on the tape 1 so that a Li ion transmission thin film 3 is formed. The hot dip coating layer 2 which is formed under an inert atmosphere such as high-purity argon atmosphere has a clean surface state and the thin film 3 formed thereon has superior performance so that it shows superior discharge capacity maintenance rate in the case of used for the negative electrode. The Li secondary battery formed by winding the tapelike negative electrode and the positive electrode together via a separator has superiority in charge/discharge cycle life, charge/discharge capacity, and energy density.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a Li secondary battery which is excellent in the performance of a Li ion permeable thin film and is excellent in charge / discharge capacity, energy density, charge / discharge cycle life, etc., and a lithium-based negative electrode and a manufacturing method thereof. Regarding

[0002]

2. Description of the Related Art Conventionally, L is placed on a tape made of lithium or a lithium alloy formed by extrusion or rolling on a negative electrode.
There has been known a Li secondary battery including an electrolyte containing LiAsF ₆ as an electrolyte and dimethoxyethane as a solvent, which is obtained by using a Li ion permeable thin film made of iF or the like. The Li secondary battery is intended to have a high discharge capacity, and the Li ion-permeable thin film in the negative electrode has a function of preventing direct contact between lithium or a lithium alloy and the electrolytic solution.

In the above, when lithium or a lithium alloy and the electrolytic solution come into direct contact with each other, they react with each other during charging and discharging, and reaction products are deposited on the surface of the negative electrode, and the maintenance rate of the discharge capacity is gradually reduced during repeated charging and discharging. To cause a problem.
Therefore, the Li ion permeable thin film is intended to prevent such a reaction and prevent the discharge capacity retention rate from decreasing.

However, the conventional negative electrode has a problem in that the Li ion-permeable thin film provided on it is inferior in performance and is poor in the effect of preventing the reduction of the discharge capacity maintenance rate. Also, because the surface of the tape made of lithium or a lithium alloy is covered with Li ₂ O, LiOH, etc.
It is difficult to attach the ion-permeable thin film in a short time with good film quality reproducibility, and it is also difficult to form the Li ion-permeable thin film as its single-phase film, and the production efficiency of the negative electrode is poor. There was a problem.

[0005]

DISCLOSURE OF THE INVENTION The present invention has a Li ion permeable thin film having excellent performance on a layer made of lithium or a lithium alloy, and the Li ion permeable thin film can be formed in a short time with good film quality reproducibility. To obtain a tape-shaped negative electrode that can be attached as a single-phase film and is excellent in manufacturing efficiency, and to obtain a Li secondary battery that has an excellent discharge capacity maintenance rate, excellent charge / discharge cycle life, and excellent charge / discharge capacity and energy density. The purpose is to

[0006]

The present invention is characterized in that a hot-dip plated layer of lithium or / and a lithium alloy is provided on a current collector tape, and a Li ion permeable thin film is provided on the hot-dipped plated layer. And a negative electrode for a Li secondary battery, and a current collector tape are introduced into a lithium or / and lithium alloy hot-dip bath under an inert atmosphere, and lithium or / and a lithium alloy is deposited on the current collector tape. After forming a coating layer, a Li ion-permeable thin film is attached on the coating layer, and a method for producing the negative electrode for a Li secondary battery, including the above negative electrode, wherein the electrolytic solution is a non-electrolyte solution. The present invention provides a Li secondary battery characterized by comprising an aqueous solution.

[0007]

[Exemplary Embodiment] A lithium alloy contains 80% or more of lithium based on an atomic ratio, and a hot-dip layer of lithium or / and a lithium alloy is rapidly cooled at a cooling rate of 300 ° C./sec or more. And a diffusion barrier layer made of nickel, cobalt or iron, and a current collector tape made of copper, aluminum or silver tape on a conductive support substrate, and silver, copper, zinc, magnesium, aluminum, calcium. , A barium, bismuth, indium, lead, platinum, palladium, or tin sequentially has a wetting promoting layer, and each of the diffusion barrier layer and the wetting promoting layer has a thickness of 0.01 to 5 μm, and a conductive support. Each thickness of the base material and the hot-dip layer is 10 to 30 μm and 10 to 50
A battery form of a Li secondary battery in which a negative electrode for a Li secondary battery having a size of μm and a tape-shaped positive electrode and a negative electrode are wound with a separator interposed therebetween.

[0008]

Since the hot-dip plated layer is formed in an inert atmosphere such as a high-purity argon atmosphere, lithium or / or lithium having a very clean surface without a film or the like made of a different kind of material is used.
And a layer composed of a lithium alloy are obtained to have a surface state suitable for surface modification and treatment, and a Li ion permeable thin film having excellent performance can be formed on it by various methods, and the discharge capacity maintenance rate is excellent. A negative electrode is obtained. Further, the Li ion permeable thin film can be attached as a single-phase film in a short time with good film quality reproducibility, and a tape-shaped negative electrode can be obtained with good production efficiency. Therefore, a large area negative electrode such as a tape, which is excellent in thickness uniformity, surface flatness, and property homogeneity, the active material does not easily fall off, the quality is stable, and the strength is excellent and is advantageous for winding treatment, A Li secondary battery that can be easily obtained, has excellent charge / discharge cycle life, and has excellent charge / discharge capacity and energy density can be obtained.

[0009]

EXAMPLE A negative electrode of the present invention has a hot-dip layer of lithium or / and a lithium alloy on a current collector tape and a Li ion-permeable thin film on the hot-dip layer. It is used for forming a secondary battery. Examples thereof are shown in FIGS. 1 and 2. 1 is a current collector tape, 2 is a hot-dip plated layer made of lithium and / or a lithium alloy, and 3 is a Li ion permeable thin film.

As is clear from FIGS. 1 and 2, the hot-dip plating layer or the like may be provided on both sides of the current collector tape,
It may be provided on one side. The current collector tape in the illustrated example is composed of a conductive support substrate 11 on which a diffusion barrier layer 12 and a wetting promoting material layer 13 are sequentially provided.

The negative electrode of the present invention can be produced by, for example, introducing the current collector tape into a hot-dip bath of lithium or / and a lithium alloy under an inert atmosphere and depositing lithium or / and a lithium alloy on the current collector tape. After the coating layer is formed, a Li ion permeable thin film may be attached on the coating layer.

As the current collector tape, for example, a conductive support base material made of a metal having excellent conductivity such as copper, aluminum or silver, and if necessary, a diffusion barrier layer, a wetting promoting material layer and the like are provided thereon. Those provided are used. The thickness of the current collector tape is appropriately determined according to the purpose of use of the electrode and the like, and is generally 100 μm or less, especially 5 from the viewpoint of thinning.
˜50 μm, especially 10 to 30 μm.

The diffusion barrier layer, which is optionally provided on the conductive support substrate, is intended to prevent the plating component from eroding the conductive support substrate during hot dipping. In the absence of the diffusion barrier layer, the conductive support substrate may react with liquid lithium or a liquid lithium alloy to become a semi-molten state and break. In addition, a component such as lithium in the hot-dip plated layer may gradually penetrate to increase the electric resistance of the current collector tape and increase the internal resistance of the battery.

Therefore, for the formation of the diffusion barrier layer, for example, an appropriate conductor which is hard to react with liquid lithium such as nickel, cobalt, iron, and / or liquid lithium alloy or its components can be used. The formation can be performed by an appropriate method such as an electroplating method, an electroless plating method, and a physical or chemical vapor deposition method. The thickness of the diffusion barrier layer is preferably 0.01 to 5 μm, and more preferably 0.05 to 1 μm. If the thickness is less than 0.01 μm, defects such as voids and pinholes are likely to occur, and if it exceeds 5 μm, the electrical resistance of the current collector tape tends to increase.

The wetting promoter layer, which is provided on the diffusion barrier layer as necessary, promotes the wetting of liquid lithium or / and liquid lithium alloy during hot dipping to prevent deterioration of the electrode surface properties such as unevenness. The purpose is to facilitate formation of a good quality negative electrode active material layer by forming a flat and uniform coating layer by hot dipping. Also, for example, 5
The purpose is to facilitate formation of a negative electrode active material layer composed of a thin coating layer having a thickness of 0 μm or less.

By thinning the negative electrode active material layer, the area of the electrode can be increased while suppressing an increase in the amount of the negative electrode active material in the battery, and the energy density and the charge / discharge capacity can be increased by increasing the electrode area. In addition, the current density can be suppressed to a low level, the lithium precipitate during charging has a dense structure, and a long charge / discharge cycle life can be achieved. Further, by thinning the layer, the bending strain applied to the negative electrode active material layer in the winding step can be reduced, and peeling, deformation, etc. of the active material layer can be eliminated.

Therefore, in the formation of the wetting promoting material layer, a suitable conductor having an affinity with liquid lithium or a liquid lithium alloy or its components, preferably liquid lithium or a liquid lithium alloy or its components, is easily reacted with its chemical affinity. It is possible to use the one excellent in. Examples thereof include silver, copper, zinc, magnesium, aluminum, calcium, barium, bismuth, indium, lead, platinum, palladium and tin.

The wetting promoting material layer can be formed by an appropriate method such as an electroplating method or a physical or chemical vapor deposition method, and the thickness thereof is 0.01 to 5 μm, preferably 0.1. ˜1 μm is preferred. The thickness of the wetting promoter layer is 0.
If it is less than 01 μm, the effect of promoting wetting of liquid lithium or a liquid lithium alloy is poor, and if it exceeds 5 μm, it may act as an impurity of the negative electrode active material layer to reduce charge / discharge capacity, electromotive force, and the like.

The hot-dip plated layer provided on the current collector tape is formed of lithium and / or a lithium alloy and serves as an active material layer of the negative electrode. In the present invention, from the viewpoint of the characteristics of the negative electrode, the thickness is 100 μm or less, especially 5 to 50 μm.
It is preferable to provide a hot-dip plating layer having a thickness of 10 to 25 μm.

The hot-dip coating layer is formed by, for example, introducing the current collector tape into a hot-dip bath of lithium or / and a lithium alloy in an atmosphere of an inert gas such as argon gas or helium gas to form the coating layer. It can be performed by a method of forming or a method of quenching the coating layer after forming the coating layer.

When forming the hot-dip coating layer, as shown in FIGS. 3 and 4, a continuous method in which a long collector tape 4 is continuously introduced into the hot-dip plating bath 5 and passed, or a predetermined length is used. An appropriate manufacturing method such as a batch method in which the current collector tape 9 is dipped in the hot dip plating bath 5 and taken out can be adopted.
In FIG. 3 or 4, 6 is a direction change roll, 7 is a coating thickness adjusting means, 8 is a cooling gas nozzle for rapid cooling, and 10 is a weight.

The quenching treatment of the hot-dip plated layer can be carried out by an appropriate method such as a method of spraying a cooling inert gas such as argon gas or helium gas onto the coating layer having a predetermined thickness. In that case, it is preferable to perform rapid cooling at a rate of 300 ° C./sec or more from the viewpoint of improving the negative electrode characteristics by making the crystal grains finer. Such rapid cooling can be easily achieved by controlling the temperature and supply amount of the cooling gas or the like. Also, the solidification time of the hot-dip layer at room temperature is usually 2 or 3
From the viewpoint of achieving a quenching treatment of 300 ° C./sec or more, it is preferable to perform a quenching treatment within 1 second after setting a predetermined coating thickness through the thickness adjusting means, if necessary. .

In the above quenching treatment, when the quenching atmosphere such as cooling gas reaches the coating thickness adjusting means, the current collector tape is fixed to the means and the wire is broken, or the coating layer is cooled before the thickness is adjusted to a predetermined value. This may cause variations in thickness, etc., so as illustrated in FIGS. 3 and 4,
It is desirable that the quenching treatment atmosphere does not reach the coating layer before the predetermined thickness. Such a purpose can be easily achieved by a method of controlling the supply direction of the cooling gas or the like and sucking and removing the gas that has finished its role.

Lithium and / or a lithium alloy is used for forming the hot-dip plating layer (coating layer). As the lithium alloy, Li and, for example, Al, Pb, S are used.
n, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, S
Examples include alloys of binary or ternary or more with metals such as r and Te to which Si, Cd, Zn, La and the like are added, if necessary, and any known material can be used.

Incidentally, as specific examples of the above-mentioned lithium alloy, for example, a Li alloy made of an intermetallic compound of Al, Bi, Sn or In and Li and Li, or an alloy of Li and Pb to which La or the like is added is used. And a Li-X-Te-based alloy containing an X component composed of at least one of Ag, Al, Mg, Zn, and Ca.

The content of components other than lithium in the lithium alloy is 40% or less based on the atomic ratio, especially 5 to 3
0%, especially 10 to 20% is preferable. Its content is 40
If it exceeds 20%, the energy density of the negative electrode active material may significantly decrease, and if it exceeds 20%, the electromotive force may decrease. If it is less than 5%, the effect of improving the properties due to alloying may be poor.

A lithium alloy that can be particularly preferably used from the viewpoints of charge / discharge cycle life, high electromotive force, high discharge capacity, high energy density, etc. is Li: Ag: Te composed of Li-Ag-Te alloy. Atomic ratio 80-150: 1-
20: 0.001 to 30 and the like, 80% Li
It contains at least atomic%.

The Li ion permeable thin film provided on the hot-dip plated layer is not particularly limited as long as it can pass Li ions. Examples of the Li ion permeable thin film include LiF, Li ₃ PO ₄ , Li ₂ S and LiC.
1, Li ₂ CO _{3 and the} like.

The Li ion permeable thin film may be provided on the hot-dip plated layer by an appropriate method because the surface of the hot-dip plated layer formed in an inert atmosphere has excellent cleanliness. Examples thereof include a solution dipping method, an electrolytic solution additive method, a gas phase reaction method, and a low temperature vapor deposition method.

The solution immersion method is a method in which the current collector tape is subjected to the above-mentioned hot dip plating and then immersed in a non-aqueous solution in which the components for forming the Li ion permeable thin film are dissolved. Can be formed into a thin film. The dissolved concentration of the film-forming component in the non-aqueous solution is 0.001-1.
The amount is preferably 00 mmol / l, especially 0.01 to 10 mmol / l. If the concentration is less than 0.001 mmol / l, it may take a long time to form a film, and if it exceeds 100 mmol / l, a dense thin film may not be formed.

Examples of the combination of the non-aqueous solution and the dissolved component described above, and the Li ion permeable thin film formed thereby include those shown in Table 1.

[Table 1]

The electrolytic solution additive system is one in which the film forming component such as iodine is added to the electrolytic solution when the Li secondary battery is manufactured. In that case, the dissolved concentration of the film-forming component in the non-aqueous solution is 0.01 to 10 mmol / l, and especially 0.1.
It is preferably from 01 to 1 mmol / l. The concentration is 0.01m
If it is less than mol / l, a film may not be formed,
If it exceeds mol / l, a dense thin film may not be formed.

In the gas phase reaction system, the hot-dip plated layer of the current collector tape is exposed to carbon dioxide gas, dilute HF gas, dilute HCl gas, dilute H ₂ S gas or the like to make the surface layer of the hot-dip plated layer into a Li ion permeable thin film. It is a method to transform.

The low temperature vapor deposition method is an appropriate method in which a vapor deposition process is performed at a low temperature such as various sputtering methods, pulse plasma methods, ion plating methods such as cluster ion vapor deposition, etc. on the hot-dip layer of a low temperature collector tape. Is a method of forming a Li ion permeable thin film consisting of a vapor deposition film. This method has an advantage that a dense Li ion permeable thin film can be formed.

The Li ion permeable thin film is for preventing contact between the hot-dip plated layer on the current collector tape and the electrolytic solution, and therefore its thickness is not particularly limited. Generally, 1 μm or less, especially 0.5 μm or less, particularly 0.01 to
The thickness is about 0.1 μm. The Li ion permeable thin film can be formed by either a continuous method or a batch method, as in the case of the hot-dip plated layer. Therefore, the negative electrode of the present invention can be formed by either a continuous method or a batch method. .

The negative electrode of the present invention is for forming a Li secondary battery. The Li secondary battery to be formed is such a negative electrode except that a non-aqueous electrolyte solution is used as the electrolytic solution. There is no particular limitation, and the other points such as the positive electrode can be the same as the conventional one. Therefore, the form of the Li secondary battery can be appropriately determined according to the purpose of use, and a porous insulating film containing a non-aqueous electrolyte solution, such as a coin type, a button type, or a wound type, can be used. An appropriate form such as a form in which a positive electrode and a negative electrode are arranged via the above can be adopted. Incidentally, the coin type is illustrated in FIG. Reference numerals 21 and 27 are battery cans, 22 and 26 are current collecting nickel plates, 23 is a negative electrode, 24 is an electrolyte layer (a separator made of a porous insulating film), 25 is a positive electrode, and 28 is an insulating sealing material.

As the electrolytic solution, a non-aqueous solution prepared by dissolving a lithium salt in an organic solvent such as ester or ether is used. As typical examples of the organic solvent, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, dimethoxyethane, dimethylsulfoxide, sulfolane, γ-butyrolactone, 1,2-dimethoxyethane, diethyl ether, 1,3-dioxolane, methyl formate, methyl acetate,
Examples thereof include N, N-dimethylformamide, acetonitrile, a mixture thereof and the like.

Typical examples of lithium salts are LiI and Li.
CF ₃ SO ₃ , Li (CF ₂ SO ₂ ) ₂ , LiBF ₄ , LiClO
₄ , LiAlCl ₄ , Li ₂ GeF ₆ , LiPF ₆ , LiSCN, L
iAsF _{6 and the} like. The concentration of lithium salt in the electrolytic solution is generally 0.1 to 3 mol / liter, but is not limited to this. In forming the non-aqueous electrolyte, 2-methylfuran, thiophene, pyrrole, crown ether, Li complex ion forming agent, if necessary, for the purpose of improving battery characteristics such as life, discharge capacity and electromotive force. It is also possible to add organic additives such as (macrocyclic compounds).

As the positive electrode, an appropriate one such as carbon or metal type, organic conductive substance type such as conjugated polymer or the like can be used. Examples of the metal-based positive electrode include Li, Ti, Mo, Cu, Nb,
Examples thereof include complex oxides of metals such as V, Mn, Cr, Ni, Co, P, sulfides, and selenides, and typical examples thereof include LiMnO ₂ , LiCoO ₂ , and Li _w Co.
_1-xy M _x P _y O _{2 + z} (where M is one or more transition metals, w is 0 <w ≦ 2, x is 0 ≦ x <1, y is 0 <y
<1, z is −1 ≦ z ≦ 4. ), Or a phosphate containing Li to Li · Co and / or an oxide of Co to Li · Co and containing 0.1 mol or more of Co and 0.2 mol or more of P per 1 mol of Li. The active material is, for example.

The positive electrode in the form of a sheet may be formed, for example, by using an active material, if necessary, a conductive material such as acetylene black or Ketjen black, and polytetrafluoroethylene, polyethylene, polyvinylidene fluoride or ethylene / propylene / diene. It can be performed by a method such as casting with a binder such as a polymer, a compression molding method, a roll molding method, a doctor blade method, various vapor deposition methods, rolling methods, hot extrusion methods and the like. . The positive electrode sheet can also be obtained as a reinforced form obtained by adhering the positive electrode material to the current collector sheet by an appropriate method such as coating and adhering with a binder resin.

On the other hand, as the porous insulating film (separator) interposed between the positive electrode and the negative electrode, an appropriate porous material such as a porous polymer film made of polypropylene or the like, a glass filter, a non-woven fabric or the like can be used. . The porous insulating film containing the electrolytic solution can be formed by an appropriate method such as a method of impregnating or filling the porous insulating film with the electrolytic solution, or a method of filling the battery can with the electrolytic solution.

The charging of the Li secondary battery can be performed by a method in which a constant current is continuously applied or a method in which a pulse current is supplied by using an appropriate pulse power source. The charging method using a pulsed current has the advantage that dendrites are less likely to grow because the change in electrolyte concentration is suppressed because energization / stopping is repeated.

Example 1 A current collector made by electroplating nickel with a thickness of 2 μm on both sides of a long copper tape having a width of 41 mm and a thickness of 10 μm, and then electroplating silver with a thickness of 0.5 μm on it. Body tape in a high-purity argon atmosphere in a hot-dip lithium bath (2
50 ° C.) at a speed of 2 m / min and continuously passed,
Use a squeezing jig to set the coating thickness on each side to 2
After adjusting to 0 μm, it is cooled by blowing argon gas on it, and then it is dissolved in phosphoric acid (0.1 mmol / l)
Was continuously introduced into the above propylene carbonate bath at the same speed as above and passed through to obtain a negative electrode tape having a Li ₃ PO ₄ thin film on the surface continuously.

On the other hand, lithium carbonate, basic cobalt carbonate, and a phosphoric acid aqueous solution having a phosphoric acid content of 85% were mixed with Li: Co: P.
= 2: 1.5: 0.5, mixed in an atomic ratio, placed in an alumina crucible and heat-treated at 900 ° C for 24 hours to obtain lithium phosphate, lithium-cobalt phosphate and cobalt oxide. After forming a mixture (active material) of the product with a ball mill and sizing it, 46 parts by weight of powder having a particle size of 20 μm or less, 4 parts by weight of acetylene black, 2 parts by weight of polyvinylidene fluoride, and N- Methylpyrrolidone 5
0 parts by weight are mixed, and the mixture is applied onto an aluminum tape having a width of 39 mm, a length of 400 mm and a thickness of 20 μm, followed by vacuum drying to form a coating layer (positive electrode layer) having a thickness of 200 μm to obtain a positive electrode tape. It was

Next, the negative electrode tape and the positive electrode tape having a length of 400 mm described above are wound with a porous polypropylene film (separator) having a thickness of 25 μm interposed therebetween and housed in a battery can, and 3 ml of an electrolytic solution is put therein. It was injected to form an AA type secondary battery. The cross-sectional area of the wound product was about 90% of the cross-sectional area inside the battery can, and the electrolyte used was 1 liter of propylene carbonate in which 1 mol of LiClO ₄ was dissolved.

Example 2 The hot-dip plated layer had a Li: Ag: Te atomic ratio of 87: 1.
3: 0.05 Li-Ag-Te based alloy (bath temperature: 350
℃), and the surface of Li ₃ PO ₄ − with a thickness of 600 Å
A negative electrode tape was obtained in the same manner as in Example 1 except that an Ag ₃ PO ₄ thin film was provided, and a Li secondary battery was obtained using the negative electrode tape.

Comparative Example 1 Example 1 was repeated, except that a commercially available lithium tape having a thickness of 100 μm was clad on both sides of a copper tape was used as the negative electrode.
A Li secondary battery was obtained according to.

Comparative Example 2 A Li secondary battery was obtained in the same manner as in Example 2 except that a tape having no Li ₃ PO ₄ -Ag ₃ PO ₄ thin film on the surface was used as the negative electrode.

Evaluation Test The secondary batteries obtained in Examples and Comparative Examples were 4.2 V (charged) to 2.8 V at a charging current and a discharging current of 100 mA.
5 charge / discharge cycles between (Discharge: 1 hour after charging)
0 times (Example 1 and Comparative Example 1) or 400 times (Example 2)
And Comparative Example 2) The discharge capacity retention rate after repetition was examined. The results are shown in Table 2. The table also shows the discharge capacity at the first cycle.

[0050]

[Table 2]

[0051]

According to the present invention, a tape-shaped negative electrode having a good Li ion permeable thin film on a clean lithium or lithium alloy surface and having an excellent discharge capacity maintenance rate can be obtained efficiently. It is possible to obtain a Li secondary battery having excellent discharge cycle life, long life, high performance, and high reliability.

[Brief description of drawings]

FIG. 1 is a sectional view of an example.

FIG. 2 is a sectional view of another embodiment.

FIG. 3 is an explanatory diagram of a manufacturing example.

FIG. 4 is an explanatory view of another manufacturing example.

FIG. 5 is an explanatory diagram of a battery example.

[Explanation of symbols]

1, 4, 9: Current collector tape 11: Conductive supporting substrate 12: Diffusion barrier layer 1
3: Wetting promoter layer 2: Hot-dip plating layer 3: Li ion permeable thin film 5: Hot-dip plating bath 23: Negative electrode 24: Electrolyte layer (separator) 25: Positive electrode

Claims (4)

[Claims] 1. A Li tape comprising a hot-dip plated layer of lithium and / or a lithium alloy on a current collector tape, and a Li ion-permeable thin film on the hot-dipped plated layer.
Negative electrode for secondary battery. 2. The current collector tape has a diffusion barrier layer made of a conductor that does not easily react with liquid lithium or / and a liquid lithium alloy on a conductive support substrate, and the liquid lithium is placed on the diffusion barrier layer. The negative electrode according to claim 1, which further comprises a wetting promoting material layer made of a conductor having an affinity for the liquid lithium alloy and / or the liquid lithium alloy. 3. After introducing the current collector tape into a hot-dip bath of lithium or / and lithium alloy under an inert atmosphere to form a coating layer of lithium or / and lithium alloy on the current collector tape. The method for producing a negative electrode for a Li secondary battery according to claim 1 or 2, wherein a Li ion permeable thin film is provided on the coating layer. 4. The Li having the negative electrode according to claim 1 or 2, wherein the electrolytic solution comprises a non-aqueous solution of an electrolyte.
Secondary battery.