JP2000340257A - Lithium secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium secondary battery restraining a short circuit caused by a generation of dendrite from a negative electrode, having a high energy density, and providing an excellent charging/discharging characteristic. SOLUTION: A lithium secondary battery has an electrolyte layer, a positive electrode, and a negative electrode made of a material containing lithium. The electrolyte layer is made of an inorganic solid electrolyte, and the positive electrode contains an organic macromolecules. The electrolyte layer preferably contains at least one type selected from a group comprising oxygen, sulfur, nitrogen, sulfide, and oxynitride. The conductivity of lithium ion of organic electrolyte of the positive electrode is preferably lower than that of the inorganic solid electrolyte of the electrolyte layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a high capacity, high safety lithium secondary battery. In particular, the present invention relates to a lithium secondary battery capable of suppressing a short circuit due to generation of dendrite from a negative electrode, having a high energy density, and having excellent charge / discharge cycle characteristics.

[0002]

2. Description of the Related Art Practical use of lithium ion secondary batteries using an organic electrolyte is progressing. The feature is that the energy output per unit volume or unit weight is higher than other batteries. In particular, practical application and development are being promoted as power supplies for mobile communications, notebook computers, and even electric vehicles.

[0003] Such lithium secondary batteries include an organic electrolyte type in which a porous polymer separator is impregnated with an organic electrolyte, and a gel polymer type in which a gel polymer containing a large amount of an organic electrolyte is used. .

However, both the organic electrolytic solution type and the gel polymer type use a large amount of the organic electrolytic solution, and there is a problem caused by the organic electrolytic solution. That is, there are voltage resistance, instability with respect to electrode materials, particularly carbon, which is usually used for a negative electrode, and generation of gas. In addition, these organic electrolytes are basically flammable substances, and have a risk of explosion due to short-circuit due to temperature rise or impact due to some cause.

[0005] Further, in the battery of the organic electrolyte type and the gel polymer type, increasing the energy density is a major technical problem. At present, about 300Wh / 1 is the limit, 400Wh
It is eager to improve to more than / 1 /. The use of lithium metal for the negative electrode has been studied as an effective means.

However, when a lithium-containing material is used as the negative electrode, the thickness of the lithium metal used for charging and discharging and the change in the shape of the negative electrode during charging and discharging affect the electrolyte layer.
In particular, this effect appears in high cycles of several hundred cycles or more. Further, lithium metal easily reacts with moisture in the air, so that a device for shutting off the atmosphere in the film formation process is required.

Further, in a lithium battery containing an organic electrolyte, during repeated charging and discharging, dendrite-like lithium metal grows on the surface of the lithium metal, which may cause an internal short circuit between the electrodes and cause an explosion. is there.

The following technique has been proposed as a technique for suppressing this danger. 1: A compound layer is formed by surface-treating lithium metal to be a negative electrode. The compound layer includes a polymer film, a fluoride film, a carbonate compound film, an oxide film, and the like.

2: An all-solid-state battery that does not contain an organic electrolyte that may cause an explosion. For example, an organic polymer, an inorganic crystal, or the like is used for the electrolyte.

[0010]

However, each of the above techniques has the following problems. 1-1: In the technology of surface treatment of lithium metal, a treatment is performed before forming a battery, and a compound is formed by spontaneously reacting with a compound in an electrolytic solution and a cathode material when forming a battery. What forms a layer is known.

1-2: In the former, an acid treatment or a plasma treatment forms a lithium fluoride, carbonate, or oxide layer, which has the effect of suppressing the growth of lithium dendrites during charge and discharge. It is said that. However, there is a problem that vacancies are generated at the interface during charge / discharge, the compound layer is separated, and cracks in the compound layer and intensive growth of lithium metal on pinholes occur.

1-3: Regarding the latter, since a substance which forms a compound layer by reacting with lithium metal in the organic electrolyte is added, as long as the lithium metal is in contact with the electrolyte, the interface is constantly maintained. To form a compound layer. For this reason, the problem such as peeling is more likely to be avoided, but the compound layer formed on the lithium metal surface becomes non-uniform due to the influence of impurity components in the unavoidably contained organic electrolyte solution, The effect of suppressing the growth of lithium metal dendrite is thin.

2-1: In the all solid type, since the electrolyte is solid, there is a problem in contact between the electrode and the electrolyte. The impedance is increased due to a decrease in the contact area, and the current value which can be taken out cannot be increased.

2-2: It is difficult to handle the solid electrolyte, and there is a limit in the form of use. As the material of the solid electrolyte, a sulfide-based material, an oxide-based material, a nitride-based material, and an oxynitride-based material or an oxysulfide-based material, which is a mixture thereof, can be considered. However, compounds containing sulfide have high lithium ion conductivity, but also have disadvantages of high hygroscopicity and hydrolyzability. Therefore, it is difficult to handle the electrolyte layer after film formation, and when assembling it into a battery, it is necessary to enclose it in an inert atmosphere for transportation, and equipment such as a glove box is required. Becomes

2-3: Examination of the use of a lithium ion conductive solid electrolyte is mainly in the form of a bulk sintered body or powder, which has a limit in the form of use, lowers the overall ionic conductivity, The performance is also low. On the other hand, when a thin-film electrolyte is used, it is difficult to suppress the formation of pinholes and cracks. In particular, when a positive electrode containing an organic electrolyte is used, the electrolytic solution from the positive electrode enters the negative electrode surface along the pinholes and cracks, and dendrites grow intensively at the pinholes and cracks due to the reaction with the negative electrode. As a result, there is a problem that a short circuit occurs between the electrodes. In addition, the volume of the negative electrode changes during charging and discharging. However, if the current capacity per unit area is increased, the negative electrode cannot fully withstand the stress due to the strain at that time, and the electrolyte layer is easily broken.

Accordingly, it is a primary object of the present invention to provide a lithium secondary battery which suppresses a short circuit due to generation of dendrites from a negative electrode, has a high energy density, and has excellent charge / discharge cycle characteristics.

[0017]

According to the present invention, the above object is achieved in that the electrolyte layer is composed of an inorganic solid electrolyte and the positive electrode contains an organic polymer. That is, while charging and discharging, the dendrite growth on the lithium metal is prevented, the reaction between the organic electrolyte and the negative electrode is suppressed, and even during overcharging, the temperature rise inside the battery is suppressed, and an explosion can be avoided. . Hereinafter, each of the electrolyte layer, the positive electrode, the negative electrode, and the battery configuration will be described in detail. These conditions can be used alone or in combination.

(Electrolyte Layer) <Material> It is effective that the electrolyte layer is an inorganic solid electrolyte. This is because the inorganic solid electrolyte forms a graded compositional interface layer with lithium metal at the interface with lithium metal. In other words, while an organic polymer has a clear interface between lithium metal and an organic polymer layer, an inorganic solid electrolyte forms a layer containing a mixture of lithium metal and a lithium-containing inorganic compound at the interface and peels off. Is preventing.

Specific examples of the inorganic solid electrolyte include sulfides, oxides, nitrides, and oxynitrides and oxysulfides which are a mixture thereof. Examples of the sulfide include Li ₂ S and a compound of Li ₂ S and SiS ₂ , GeS ₂ , and Ga ₂ S ₃ . Also, as the oxynitride,
_{Li 3 PO 4-X N 2X} / 3, Li 4 SiO 4-X N 2X / 3, Li
_{4 GeO 4-X N 2X /} 3 (0 <X <4), Li 3 BO 3-X N
_{2X / 3} (0 <X <3).

In particular, the inclusion of sulfur facilitates the formation of a gradient composition layer on the surface of lithium metal.
This prevents a gap from being formed at the interface between the lithium metal and the solid electrolyte layer during the deposition and dissolution of the lithium metal at the negative electrode during charge and discharge, and prevents the solid electrolyte layer from peeling due to intrusion of the organic electrolyte solution. be able to.

It has also been found that the effect is enhanced by containing at least one of oxygen and nitrogen in addition to sulfur. This is because oxygen or nitrogen has high reactivity with the lithium metal and more strongly bonds the inorganic solid electrolyte layer and the lithium metal. Also, 10 ^-3
A high ionic conductivity of 1010 ⁻² S / cm can be realized.
This is considered to be caused by the polarity between the constituent elements and the effect of introducing strain. In addition, these materials, especially,
It has the effect of suppressing the high hygroscopicity, which is a drawback of oxysulfides.

It is desirable that the lithium element content in these inorganic electrolyte layers is not less than 30 atomic% and not more than 65 atomic%. If it is less than 30 atomic%, the ionic conductivity becomes low and the resistance becomes high. Further, the adhesion between the inorganic solid electrolyte layer and the lithium metal layer is reduced. On the other hand, when the composition exceeds 65 atomic%, the adhesion between the inorganic solid electrolyte layer and the lithium metal layer is improved, but the inorganic solid electrolyte layer is polycrystallized and becomes porous, so that a dense inorganic solid electrolyte continuous film is formed. It becomes difficult to form. In addition, electron conductivity develops and causes an internal short circuit when a battery is constructed, thereby lowering battery performance. Therefore, the electrolyte layer is preferably an amorphous body.

In the inorganic solid electrolyte, other than lithium, one or more elements selected from the group consisting of phosphorus, silicon, boron, aluminum, germanium and gallium (hereinafter, these elements are referred to as "additional elements") )
, And preferably contains sulfur. It is effective that the inorganic solid electrolyte is an amorphous body, but the “additional element” can form a network structure through sulfur to form this amorphous skeleton, and Sites of optimal size for the conduction of ions can be provided. Also, "additive element"
Can charge a terminal sulfur atom of an amorphous skeleton to a negative charge having an optimum intensity for capturing a positively charged lithium ion. In other words, the negatively charged terminal sulfur atoms function to moderately and slowly capture the positively charged lithium ions, and serve to assist the conduction of lithium ions without being unnecessarily firmly fixed.

Further, as a content component other than lithium of the inorganic solid electrolyte, at least one of oxygen and nitrogen in addition to the "additional element" and sulfur is exemplified. The inclusion of oxygen or nitrogen makes it possible to exhibit higher lithium ion conductivity. This is presumably because the inclusion of oxygen atoms or nitrogen atoms has the effect of widening the gaps between the formed amorphous skeletons, thereby reducing the hindrance of lithium ion migration.

In addition, the effect of containing the "additional element" in the inorganic solid electrolyte is to improve the adhesion between the inorganic solid electrolyte layer and the lithium metal. When the inorganic solid electrolyte contains the “additional element”, the inorganic solid electrolyte has a performance of further improving the affinity with lithium metal. As already described, the inclusion of lithium, sulfur, oxygen, and nitrogen improves the adhesion between lithium metal and the inorganic solid electrolyte layer,
Conversely, when an element other than the "additional element" is contained, the affinity between the inorganic solid electrolyte layer and the lithium metal is impaired, which tends to facilitate peeling.

<Ionic conductivity> The constituent material of the electrolyte layer is as follows:
Its ionic conductivity is important. That is, in the conventional techniques, the ionic conductivity of the compound layer formed on the surface of lithium metal was extremely low at room temperature, ie, 10 ⁻⁷ S / cm or less. Therefore, even though this compound layer is a thin film of several nm (nanometers) through an unavoidable pinhole or crack, an organic electrolyte having an ion conductivity of the order of 10 ⁻³ S / cm. Penetrate into the interface between the lithium metal and the compound layer, and the flow of lithium ions leans toward the organic electrolyte having high ionic conductivity. Therefore, it was found that the interface between the lithium metal and the compound layer was eroded, so that the compound layer was easily peeled off, and the coating effect was thin.

On the other hand, in the present invention, by forming an electrolyte layer having high ion conductivity, the flow of lithium ions is mainly passed through the electrolyte layer, and the above-mentioned problem is solved. The lithium ion conductivity of such an electrolyte layer is
It is preferably at least 10 ⁻⁵ S / cm at 25 ° C. Even if pinholes or cracks are present in the electrolyte layer (thin film), carbon dioxide ions inevitably contained as impurities in the electrolyte,
Oxygen gas, water molecules or fluorine ions react with lithium metal in pinholes and cracks to form a low ion conductive layer of lithium carbonate, lithium oxide, lithium fluoride, or the like on the surface of the lithium metal. Therefore, pinholes and cracks are protected by the low ion conductive layer to suppress dendrite growth, and lithium ions mainly pass through the electrolyte layer. More preferably, the ionic conductivity of the solid electrolyte layer is set to 10 times the ionic conductivity of the organic electrolyte.
% 5 × 10 ⁻⁴ S / cm or more (at 25 ° C.). An even more preferable lithium ion conductivity (25 ° C.) is 1 × 10
⁻³ S / cm or more.

In order to effectively form the lithium ion and the low ion conductive compound, it is preferable to combine at least one of the following conditions.

Carbon dioxide, a halide, an anionic polymerizable organic monomer, or an organic molecule which forms a compound with lithium is positively contained in the organic electrolyte in advance.

As an electrolytic salt (solute) of the organic electrolytic solution, an imide-based organic lithium or the like which can easily elute a fluorine compound is used.

As the positive electrode material, a disulfide-based organic material or the like which elutes a sulfur compound into an organic electrolyte is used.

<Two-layer structure> The above-mentioned inorganic solid electrolyte layer
With the layer structure, the handling is further facilitated. As a material for the electrolyte layer, a sulfide-containing lithium ion conductive compound has high lithium ion conductivity, but also has disadvantages of high hygroscopicity and hydrolyzability. On the other hand, a lithium ion conductive compound containing an oxide has chemical stability to the atmosphere but has a low ion conductivity and a compound chemically unstable to lithium metal of the negative electrode. Has become. Therefore, the electrolyte layer is composed of two layers, a negative electrode side layer and a positive electrode side layer. The negative electrode side layer is a thin film of a lithium ion conductive compound containing sulfide (lithium sulfide or silicon sulfide), and the positive electrode side layer is an oxide. When a thin film of a lithium ion conductive compound containing is used, it is possible to form an electrolyte layer that is stable to the atmosphere and has high ion conductivity.

The positive electrode side layer functions as a protective film for preventing the reaction with moisture in the air, and dissolves in the organic electrolyte when the battery is constructed. Further, the dissolved constituent elements of the positive electrode side layer react with lithium metal in pinholes and cracks in the electrolyte to form a low ionic conductive layer, thereby suppressing intensive growth of dendrites.

The positive electrode side layer serving as a protective film contains phosphorus,
Further, a lithium ion conductor containing at least one of oxygen and nitrogen is effective. That is, a phosphoric acid compound or a phosphate nitrogen compound is a suitable material.

The Li component of the positive electrode side layer is 30 atomic% or more and 50 atomic% or more.
It is effective that the ratio is at most atomic%. If it is less than 30 atomic%, the possibility of remaining undissolved during dissolution increases. Also, 50
If the composition exceeds atomic%, hygroscopicity appears, and the composition does not serve as a protective film.

The thickness of the positive electrode side layer is preferably thin. However, if the thickness is too small, the effect of shielding the sulfide-containing negative electrode side layer from the atmosphere is reduced. Therefore, 10 nm or more or 1% or more of the thickness of the negative electrode side layer is preferable. Conversely, if the positive electrode side layer is too thick, it will be difficult to maintain high ionic conductivity or it will be difficult to dissolve. Therefore, the thickness is preferably 25 μm or less or 50% or less of the thickness of the negative electrode side layer. In particular, when the negative electrode side layer is a thin film of a lithium ion conductive compound containing a sulfide and the positive electrode side layer is a thin film of a lithium ion conductive compound containing an oxide, the thickness of the positive electrode side layer is 0.1 μm.
m or more and 2 μm or less is preferable in terms of battery characteristics.

<Thickness> The total thickness of the electrolyte layer is preferably 50 nm or more and 50 μm or less. When the thickness exceeds 50 μm, the coating effect is further enhanced, but the ionic conductivity is deteriorated and the battery performance is reduced. In addition, the time and energy required to form the film are too large, which is not practical. In particular, the ion conduction resistance of the electrolyte layer is increased, and a problem arises in that the output current cannot be increased. If the thickness is less than 50 nm, the electron-conductive component becomes large, causing a problem that self-discharge is likely to occur. In addition, it becomes difficult to suppress the formation of pinholes in the electrolyte of the thin film, and when a positive electrode containing an organic electrolyte is used, the electrolyte from the positive electrode penetrates the negative electrode surface through the pinholes and contacts the negative electrode. The reaction causes the problem of dendrite formation.

In particular, in the case of the two-layer structure, a preferable total thickness of the electrolyte layer is 2 μm or more and 22 μm or less.
When the thickness is less than 2 μm, it is difficult to suppress the formation of pinholes and cracks in the electrolyte of the thin film. In other words, when an anode containing an organic electrolyte is used, the electrolyte from the anode penetrates into the negative electrode surface through pinholes and cracks, and forms dendrites through the pinholes and cracks by reaction with the negative electrode, and short-circuits between the electrodes. Happens.
In addition, the volume of the negative electrode changes during charging and discharging. However, if the current capacity per unit area is increased, the negative electrode cannot fully withstand the stress due to the strain at that time, and the electrolyte layer is easily broken. On the other hand, if the thickness exceeds 22 μm, the ion conduction resistance of the electrolyte layer becomes high, and a current density per unit area cannot be increased, resulting in a problem that efficiency is deteriorated.

(Positive electrode) <Material>

As the material of the positive electrode, a material containing an active material in a binder of an organic polymer is preferable. As the binder, at least one selected from the group consisting of a polyacrylonitrile-based polymer, a polyethylene oxide-based polymer, and a polyvinylidene fluoride-based polymer containing an organic solvent such as ethylene carbonate, propylene carbonate, or dimethyl carbonate is preferable. It is. The active materials include LixCoO ₂ , LixMn ₂ O ₄ , LixNiO ₂
At least one of (0 <X <1) is preferable. Further, it is desirable to mix a carbon powder in order to impart electronic conductivity.

In addition, the organic polymer in the positive electrode material may be a polyaniline-containing disulfide polymer or polypyrrole polymer having both ionic conductivity and electron conductivity.

When any of the above is used as the organic polymer,
It is important to contain any lithium salt of LiPF ₆ and LiCF ₃ SO ₃ . As a result, good contact between the electrolyte layer and the positive electrode can be obtained, and the resistance at the interface with the positive electrode, which has been a problem in the solid electrolyte, can be significantly reduced. Therefore, a large output current can be obtained. Further, the generation of gas and the deterioration of battery performance due to application of an overvoltage during charging and leaving the battery in a charged state, which have been a problem in the past, are greatly reduced.

Further, by adding a lithium ion conductive solid electrolyte powder to the positive electrode, the amount of the organic electrolyte component can be further reduced, and the problems caused by the organic electrolyte can be reduced. As this solid electrolyte,
It is preferable to use the high ion conductive material described above, but any material having an ion conductivity of 10 ⁻³ S / cm or more may be used.

<Organic Electrolyte in Positive Electrode> It is difficult to completely remove the organic electrolyte from the practical viewpoint of battery performance. However, the organic electrolyte is contained mainly around the active material in the positive electrode, and lithium metal is used as the negative electrode.
Forming an inorganic lithium ion conductive thin film on the negative electrode,
These can be combined into a high-performance battery. The advantages of this type of lithium secondary battery include a reduction in the amount of organic electrolyte, suppression of dendritic growth of metallic lithium on the anode, suppression of contact with the cathode due to the effect of covering the anode surface, and suppression of reaction with the electrolyte. .

Although there are still some unclear points regarding the mechanism of generation of gas caused by the organic electrolyte, the content of the organic electrolyte can be improved by using the battery of the present invention when the organic electrolyte is contained. Can be greatly reduced to 10% or less of the conventional one. Further, it has been found that even when the battery is left in a charged state, the phenomenon that the electrolytic solution is decomposed and deteriorated as in the related art and the battery characteristics are greatly reduced can be suppressed as much as possible.

When pinholes or cracks are formed in the solid electrolyte thin film, lithium metal is intensively grown along the site during charging, and an internal short circuit is likely to occur. Therefore, a method for preparing stable organic charge / discharge characteristics and safety even in the presence of these pinholes and cracks by preparing an organic electrolyte solution contained in the positive electrode will be described below.

First, the ionic conductivity of the organic electrolytic solution is suppressed to less than that of the solid electrolyte thin film. This is a pinhole,
Even if cracks are present and the organic electrolyte penetrates into them and forms an ion conduction path, Li ions are mainly transmitted through the solid electrolyte thin film layer having high ionic conductivity. Supply of Li ions is suppressed, and the growth of metallic lithium is suppressed. From the beginning, of course, the organic electrolyte of the lithium ion conductivity is lower than that of the inorganic solid electrolyte, and the organic electrolyte of the positive electrode comes into contact with the lithium-containing material of the negative electrode. The ion conductivity may be lower than that of the inorganic solid electrolyte.

There are various methods for reducing the ionic conductivity of the organic electrolyte. For example, reducing the amount of solute in the electrolyte component, or Sulfolan
e; Tetrahydrothiophene1,1-dioxide) Solvents with high viscosity and high ionic conductivity, such as solvents, may be used.

Second, an organic electrolyte containing an organic solvent that is reduced and decomposed when the organic electrolyte comes into contact with lithium metal is used. This is due to the effect of being decomposed by reduction and partially gasifying, blocking the Li ion conduction path in pinholes and cracks, and reducing the ion conductivity. Specifically, when a carboxylic acid ester is used as an organic solvent, this effect is high, and methyl formate or the like is used.

Third, when the organic electrolytic solution comes into contact with lithium metal, the organic solvent in the organic electrolytic solution is polymerized by the catalytic action or polymerization initiation action of lithium metal, and solidifies or becomes highly viscous. Lowering the Li ion conductivity and suppressing the growth of lithium metal by the mechanical action of the produced polymer or high-viscosity material. Here, even if the solid electrolyte thin film is peeled off, the organic electrolyte solution leaches out, and these polymers and high-viscosity materials constantly cover the pinholes and cracks on the lithium metal surface. It is possible to construct a safe battery.

As an organic solvent which solidifies and becomes highly viscous upon contact with lithium metal, an anionic polymerizable monomer having an olefin bond such as styrenes, acrylonitriles, methyl acrylates, butadienes, isoprenes and the like can be used. Use or use what is included. It is also possible to use a solvent which solidifies and vitrifies by the action of lithium metal, like acetonitrile having a nitrile group.

(Negative Electrode) <Material> The lithium-containing material used for the negative electrode includes not only lithium metal itself but also a lithium alloy. Specific examples of the lithium alloy include alloys with In, Ti, Zn, Bi, Sn, and the like.

Further, on the surface of the lithium-containing material, a metal thin film such as Al, In, Bi, Zn, or Pb which forms an alloy or an intermetallic compound with lithium may be formed. By using the negative electrode made of the metal thin film and the lithium-containing material, the movement of the lithium metal during charging and discharging is smooth, and the thickness of the lithium metal used is increased. In addition, the deformation of the negative electrode during charge and discharge becomes uniform, and strain on the electrolyte layer can be reduced. This is probably because the interface in contact with the electrolyte layer was stabilized. The effect of smooth movement of lithium metal and reduction of distortion to the electrolyte layer is exhibited if the negative electrode has a multilayer or inclined structure. Furthermore, Al, In, B
Since i, Zn, Pb, etc. are relatively stable to the atmosphere, and this covers the negative electrode serving as a substrate when forming the electrolyte layer,
It is possible to stabilize production and simplify the process.

The above-mentioned lithium-containing material may be used without any pretreatment when forming the electrolyte layer. However, in general, a thin oxide layer is often formed on the surface of a metal containing lithium, and it is more preferable to remove this oxide layer once and form a nitride layer or a sulfide layer. Thereby, the electrolyte layer can be directly formed into a lithium alloy material, and the impedance between the lithium-containing metal and the solid electrolyte layer can be further reduced.
As a means for removing the oxide layer, there is an argon plasma treatment. In addition, as a method of forming nitride or sulfide,
Exposing the surface of the lithium-containing material to high-frequency plasma in a nitrogen gas atmosphere or a hydrogen sulfide atmosphere includes, but is not limited to. Further, even if the film is heated to a temperature equal to or higher than the melting point of lithium metal after film formation, removal of the oxide layer on the surface of the lithium metal and formation of the sulfide layer are possible.

<Surface Roughness> The surface roughness (Rmax) of the negative electrode also greatly affects the performance of the battery. Rmax value of 0.01 or more and 5μ
m or less is preferable. When Rmax is less than 0.01 μm, good bonding with the electrolyte layer cannot be obtained, and peeling tends to occur. In addition, during charge and discharge, smooth deposition and ionization of lithium metal may not be performed. This seems to be related to the adhesion to the electrolyte. On the other hand, if Rmax exceeds 5 μm, it is difficult to form a dense electrolyte layer without pinholes, which is not preferable.

(Battery Shape / Structure) A battery having the above-described positive and negative electrodes and an electrolyte layer has a laminated structure in which an electrolyte layer is sandwiched between a positive electrode and a negative electrode, and this laminate is housed in a battery case. It is composed by closing. More specifically, first, the negative electrode current collector and the negative electrode are joined, and an inorganic solid electrolyte thin film containing no organic electrolyte is formed on the lithium-containing material to be the negative electrode, and the joined body of the negative electrode and the electrolyte is formed. Make it. Further, a positive electrode material containing an organic polymer is formed on a positive electrode current collector (for example, copper or aluminum foil) to obtain a positive electrode. These junctions and the positive electrode are combined to produce a lithium secondary battery. Thereby, the contact resistance between the negative electrode and the positive electrode and the electrolyte layer can be reduced, and good charge / discharge characteristics can be obtained. In addition to the button-type battery stacked in this way, a negative electrode, an electrolyte layer, and a positive electrode may be stacked and wound into a cylindrical shape.

Further, a separator may be provided between the positive electrode and the solid electrolyte layer. As the material of the separator, a material which has pores through which lithium ions can move and which is insoluble and stable in the organic electrolyte solution is used. For example, a nonwoven fabric or a porous material formed from polypropylene, polyethylene, a fluorine resin, a polyamide resin, or the like can be used. In addition, a metal oxide film having pores may be used.

It is not necessary to provide a lithium-containing material in the negative electrode from the beginning. Even if the structure has an inorganic solid electrolyte layer formed directly on the current collector of the negative electrode, the performance of the lithium secondary battery can be sufficiently improved. Demonstrate. That is, a sufficient lithium component is contained in the positive electrode, and lithium metal can be stored between the negative electrode current collector and the inorganic solid electrolyte layer during charging.

[0059]

Embodiments of the present invention will be described below. (Example 1-1) 100 μm thick, 100 mm × 50 mm serving as a current collector
And a lithium metal foil having a thickness of 50 μm and the same size was bonded to the copper foil. As a method of bonding, rolling may be performed by twin rolls. In this case, the surface accuracy of the roll needs to be smooth enough to achieve the target surface roughness of lithium. Also, good bonding can be obtained by raising the temperature to around the melting point of lithium metal. The surface accuracy of this lithium metal was Rmax = 0.1 μm as measured by an STM (scanning tunneling microscope).

On this lithium metal, an RF magnetron
Li by sputtering₂S-SiS₂-Li ₄SiO₄A mixture of
The target is a solid electrolyte in a nitrogen gas atmosphere.
A thin film was formed. The thickness is 10 μm, and the composition of the thin film is
EPMA (Electron Probe Micro Analyzer) analysis results
As a result, in molar ratio, Li (0.42) ・ Si (0.13) ・ N (0.01) ・ O (0.0
1) · S (0.43) Also, by X-ray diffraction
Was amorphous only in the halo pattern.

A mixture of ethylene carbonate (EC) and propylene carbonate (PC) is heated to cool polyacrylonitrile (PAN) at a high concentration, and the mixture is cooled to form a mixture of EC and PC in which LiPF ₆ is dissolved. A PAN containing a large amount of is prepared. In this PAN, LiCoO ₂ particles serving as an active material and carbon particles for imparting electron conductivity are mixed, and applied on an aluminum foil having a thickness of 100 μm to a thickness of 300 μm to prepare a positive electrode.

A lithium metal having a solid electrolyte membrane formed thereon,
A battery was fabricated by joining the above positive electrode, and a lead wire was drawn out and sealed in an aluminum laminate.

The charge / discharge characteristics were evaluated under the condition of a current value of 100 mA. As a result, the charging voltage is 4.2V and the discharging voltage is
The capacity at 3.0 V was 0.5 Ah (ampere hour). The energy density was 490 Wh (watt hours) / l (liter).

Further, when the charge and discharge were repeated 1,000 times under the same conditions, the deterioration of these characteristics was suppressed to 2%, and no trace of dendritic growth from the lithium metal of the negative electrode was observed at all. In addition, no gas or the like was generated, and extremely good stability was exhibited.

As the active material in the positive electrode, LixMn ₂ O ₄ , Li
Almost the same results were obtained using xNiO ₂ . Similarly, good results were obtained even when a polyethylene oxide-based polymer or a polyvinylidene fluoride-based polymer was used as the material in the positive electrode. Further, the same results were obtained with propylene carbonate or dimethyl carbonate containing any of LiBF ₄ , LiClO ₄ and LiCF ₃ SO ₃ as the electrolyte.

(Example 1-2) In the battery configuration shown in Example 1-1, a polyaniline-containing disulfide-based polymer was used as the positive electrode material instead of the PAN-based material. Further, the polymer material has a particle size of 0.1 μm to 0.5 μm, Li
(0.42) ・ Si (0.13) ・ O (0.01) ・ S (0.44)
% By volume. These fine particles are Li ₂ S—SiS ₂ —Li ₄ SiO
The mixed melt of No. ₄ was produced by spray quenching and solidification by an atomizing method in a dry nitrogen gas atmosphere. The thickness of the positive electrode was 350 μm.

The charge / discharge characteristics of this prototype battery were evaluated. As a result, the charging voltage was set to 4.2 V, and 50 mA was discharged.
The capacity at a discharge voltage of 3.0 V was 0.49 Ah (ampere hour). The energy density is 400Wh (watt-hour) / l
(Liter). Furthermore, when the charge / discharge cycle was performed 1000 times under the same conditions, the deterioration of these characteristics was 2%.
And no trace of dendritic growth from the lithium metal of the negative electrode was observed. In addition, no gas or the like was generated, and extremely good stability was exhibited.

(Example 1-3) Table 1 shows the results of evaluating the charge / discharge characteristics of the battery configuration shown in Example 1-1 by changing the thicknesses of the positive electrode, the electrolyte, and the negative electrode. By increasing the thickness of the electrode layer, it is possible to increase the output per unit area, but the time required for charging is correspondingly increased, and the practicality is increased. In particular, the thickness of the positive electrode is 2 μm or more and 10
The thickness of the negative electrode is preferably 1 μm or more and 200 μm or less, and the thickness of the electrolyte layer is suitably 1 μm or more and 50 μm or less.

[0069]

[Table 1]

(Example 1-4) Table 2 shows the results of evaluating the charge / discharge characteristics of the battery configuration shown in Example 1-1 while changing the surface roughness of the negative electrode. It is understood that the surface roughness affects the film quality of the electrolyte layer formed on the upper portion. That is, when the surface roughness of the negative electrode exceeds 5 μm, pinholes occur in the electrolyte layer, and the charge and discharge cycle is short-circuited 300 times.

[0071]

[Table 2]

(Example 1-5) In the battery configuration shown in Example 1-2, the surface of the lithium-indium alloy of the negative electrode was previously nitrided to form a nitride layer, and then the solid electrolyte membrane was similarly formed. Was formed to produce a battery. Observation and analysis of this nitride layer by TEM (Transmission Electron Microscope) and the like revealed that the composition was Li ₃ N and its thickness was about 100 Å. This nitride layer was obtained by exposing the surface with RF plasma in a nitrogen atmosphere before forming the solid electrolyte layer.

The charge / discharge characteristics of this prototype battery were evaluated. As a result, even when the charging voltage was 4.2 V and the current was as high as 200 mA, the capacity until the voltage dropped to 3.0 V was as high as 0.49 Ah (ampere hours). The energy density was 400 Wh (watt hours) / l (liter). Furthermore, when 1000 cycles of charge and discharge were performed under the same conditions, the deterioration of these characteristics was suppressed to 3%,
No trace of dendrite-like growth from lithium metal of the negative electrode was observed.

(Example 2-1) A current collector made of a copper foil having a thickness of 20 μm and 100 mm × 50 mm was bonded to a lithium metal foil (negative electrode) having a thickness of 10 μm and the same size as a base material. On this lithium metal foil surface, a thin film of a lithium ion conductive compound containing a sulfide is formed, and a thin film of a lithium ion conductive compound containing an oxide is further laminated to form an electrolyte layer having a two-layer structure. . The electrolyte layer was formed by an in-line type RF magnetron sputtering method.

Making Li-ion Conductive Containing Sulfide
To form the compound thin film, Li₂S-SiS ₂Target mixture
The solid electrolyte thin film in an argon gas atmosphere.
A film was formed. The thickness is 10 μm and the composition of the thin film is EP
MA (Electron Probe MicroAnalyzer) analysis results
Li: Si: S = 0.42: 0.13: 0.45
Do you get it. Also, in X-ray diffraction, only the halo pattern
It was in an amorphous state.

To form a thin film of a lithium ion conductive compound containing an oxide, a thin film of a lithium ion conductive compound containing a sulfide is further formed on a thin film of a lithium ion conductive compound in a nitrogen atmosphere by using Li ₃ PO ₄ as a target. Formed, but the thickness is 1
μm.

The negative electrode and the electrolyte layer were exposed to air for 6 hours.
After leaving for a while, no change in the composition of the sulfide layer was observed, and it was found that the composition was extremely stable. In addition, the ion conductivity showed good performance without substantially lowering the high ion conductivity of the sulfide layer.

A mixture of ethylene carbonate (EC) and propylene carbonate (PC) was heated to dissolve a high concentration of polyacrylonitrile (PAN) and cooled to obtain LiP.
EC of F ₆ is dissolved to prepare a PAN containing a large amount of your PC. In this PAN, LiCoO ₂ particles as an active material and carbon particles for imparting electron conductivity were mixed, and applied on a 20 μm-thick aluminum foil (positive electrode current collector) with a thickness of 300 μm to form an anode. The joined body of the negative electrode and the electrolyte layer and the anode were joined to form a battery, and its performance was tested.

As a result, assuming that the charging voltage is 4.2 V, 100 mA
0.5A capacity until voltage drops to 3.0V by discharge
h (ampere hours). The energy density is 4
It was 90 Wh (watt hours) / 1 (liter). further,
After 1000 cycles of charge and discharge under the same conditions, the deterioration of these characteristics was suppressed to 2%, and no trace of dendrite-like growth from lithium metal of the negative electrode was observed. In addition, no gas or the like was generated, and extremely good stability was exhibited.

(Comparative Example 2-1) In Example 2-1, the thickness of the thin film of the sulfide-containing lithium ion conductive compound was changed.
The thickness of the thin film of the lithium ion conductive compound containing an oxide was set to 0.5 μm, and the thickness of the thin film of the lithium ion conductive compound containing the oxide was set to 5 μm. A battery with performance was not obtained.

In the structure of Example 2-1, a thin film of a lithium ion conductive compound containing an oxide was formed as a lithium titanate-based amorphous to a thickness of 1.8 μm, and the other parts were the same as those of Example 2. A battery having the same structure as that of -1 was produced and its performance was tested, and good results were obtained.

(Example 2-3)

In Example 2-1, a battery was manufactured by changing the thickness of the sulfide layer and the oxide layer variously by changing the thin film of the oxide-containing lithium ion conductive compound to lithium phosphate-based amorphous. Table 3 shows the results of testing the performance. In the “Battery Characteristics” in the table, ◎ indicates that the property was stable even at 1000 cycles or more, ○ indicates that the property was stable even at 500 cycles or more, and x indicates that the performance was reduced by 5% or more at less than 500 cycles.

[0084]

[Table 3]

(Example 2-4) Rolling by twin rolls
A negative electrode was produced by laminating a 5 μm thick indium metal foil on a 50 μm thick lithium metal foil. As a result of the analysis, the interface between the two metals was diffused with each other and the composition was graded, but the surface was indium alone.

Using this as a substrate, an electrolyte layer was formed by the method described in Example 1 to produce a battery, and a charge / discharge experiment was performed under the conditions of 1 mA / cm ² (milliampere / square centimeter). The current capacity was 20 mAh / cm ² (milliamp-hour / square centimeter), and almost all lithium metal was used for charging and discharging, including lithium ions present in the anode. Further, the charge / discharge cycle was performed up to 1000 cycles under the same conditions, but the charge / discharge curve was stable with no significant change. Also, generation of dendrites and the like was not observed.

Example 3-1 A ferrite-based stainless steel foil (negative electrode current collector) having a thickness of 20 μm and a size of 100 mm × 50 mm was coated with a thickness of 10 mm.
A lithium metal foil (negative electrode) of the same size with a thickness of μm was bonded. Rolling was performed using a roll as a bonding method.

[0088] On the lithium metal foil, by laser ablation, with a mixture of _{Li 2 S-SiS 2 -Li 4} Si0 4 to the target, in argon gas atmosphere to form a solid electrolyte thin film. The thickness was 10 μm, and the composition of the thin film was Li: Si: O: S = 0.4 in molar ratio as a result of EPMA analysis.
It turned out to be 2: 0.13: 0.02: 0.43. In the X-ray diffraction, only the halo pattern was in an amorphous state.
Furthermore, the lithium ion conductivity of the solid electrolyte thin film is 1 ×
It was 10 ⁻³ S / cm (room temperature: the same applies hereinafter).

A vinylidene fluoride monomer, acetonitrile, LiPF ₆ , LiCoO ₂ particles, and carbon particles of a conductive additive were mixed, and a polymerization initiator (oxygenated triisobutylboron) was mixed. A current collector) is coated to a thickness of 100 μm and polymerized to produce a gelled positive electrode. The lithium ion conductivity of the organic electrolyte in the positive electrode was 5 × 10 ⁻² S / cm.

A battery was fabricated by joining the lithium metal foil on which the solid electrolyte membrane was formed and the above-mentioned anode, and a lead wire was taken out and sealed in an aluminum laminate.

The charge and discharge characteristics were evaluated and a crack test was performed. In the crack test, a battery once produced is bent to cause a crack in the solid electrolyte layer, and a change in charge / discharge characteristics is observed.

As a result, in the charge / discharge curve of the normal operation, a decrease in current efficiency (80%) which was considered to be caused by weak internal leak caused by pinholes in the solid electrolyte thin film was conventionally observed. The example battery had nearly 100% current efficiency. On the other hand, in the crack test, no internal short circuit was observed, and almost no decrease in current efficiency was observed. For comparison, using a mixed solvent of propylene carbonate and dimethyl carbonate as the organic solvent, similarly prepared a battery,
A crack test was performed, but it was considered that there was almost no voltage rise during charging, charging was impossible, and an internal short circuit occurred.

As the active material in the positive electrode, LixMn ₂ O ₄ , LixN
Almost the same results were obtained using iO ₂ . Also,
Similarly, good results were obtained when a polyethylene oxide polymer or a polyacrylonitrile polymer was used as the material in the positive electrode. Further, good results were obtained with any of LiBF ₄ , LiClO ₄ and LiCF ₃ SO ₃ as the electrolyte.

(Example 3-2) In the battery configuration shown in Example 3-1, an N, N-dimethylformamide solvent (DMF) containing acrylonitrile was used instead of acetonitrile. The lithium ion conductivity of the organic electrolyte using this solvent was 2 × 10 ⁻² S / cm.

As a result, the same good characteristics as in Example 3-1 were obtained. The same results were obtained when styrene, acrylate, methacrylonitrile, methacrylate, butadiene derivative and isoprene derivative were used.

(Example 3-3) In the battery configuration shown in Example 3-1, an organic electrolyte solution was prepared in which the dissolved mass of the organic electrolyte solution was reduced to 25% of the ordinary amount. In the same manner as in the above, a lithium battery was produced. Due to the above reduction in the dissolved mass, the lithium ion conductivity was lowered to 5 × 10 ⁻⁴ S / cm.

A charge / discharge characteristic and a crack test of this battery were performed. According to the charge / discharge curve, a current density of 95% or more was obtained. In the crack test, the current density was slightly reduced, but the characteristics were almost maintained. Further, even with the cycle characteristics of 500 times, the current density was decreased due to the cracks of the solid electrolyte thin film layer caused by the charge and discharge in the past, but the performance of the battery of the configuration of the present example was almost decreased. Was not observed, indicating good cycle characteristics.

(Example 3-4) In the battery configuration shown in Example 3-1, a separator was provided between the negative electrode and the positive electrode, and methylsulfolane was used instead of acetonitrile. Produced. The lithium ion conductivity in the separator of the organic electrolyte using this solvent is 7 × 10
^-4 S / cm. As a result, the same good characteristics as in Example 1 were obtained, and the cycle characteristics also showed good results.

Example 3-5 A lithium battery was fabricated in the same manner as in Example 3-1 except that methyl formate was used instead of acetonitrile. The lithium ion conductivity of the organic electrolyte using this solvent is 1 × 10 ⁻³ S /
cm. As a result, good characteristics similar to those in Example 3-1 were obtained, and the cycle characteristics also showed good results.

Example 4-1 A 200 μm (micron meter) thick lithium metal was laminated on a current collector made of nickel metal having a diameter of 1 inch to form a negative electrode. Li ₂ S, P ₂ S ₅ , Li ₃ PO by RF magnetron sputtering
_Using the mixture of No. ₄ as a target, a solid electrolyte thin film was formed on the negative electrode. As a result of the analysis, the solid electrolyte membrane was composed of 34 atom% of lithium, 14 atom% of phosphorus, 51 atom% of sulfur,
It turned out to be amorphous consisting of 1 atomic% of oxygen. The thickness of this thin film was 800 nm (nanometer).

The lithium ion conductivity of this amorphous thin film was 7 × 10 ⁻⁴ S / cm. The ionic conductivity was measured by forming a comb-shaped gold electrode on a glass substrate containing no alkali ions, forming the same thin film thereon, and using the complex impedance method.

LiCoO ₂ particles as an active material, carbon particles for imparting electron conductivity, and polyvinylidene fluoride were mixed together with an organic solvent, and coated on an aluminum foil to obtain a positive electrode. The thickness of the active material layer was 80 μm, the capacity density was 3.5 mAh (milliamp-hour) / cm ² (square centimeter), and the total capacity was 17.2 mAh.

Under an argon gas atmosphere having a dew point of −60 ° C. or less,
The negative electrode, the separator (porous polymer film), and the positive electrode each having the solid electrolyte thin film formed thereon are placed in a stainless steel sealed container so as to be stacked, and further added to a mixed solution of ethylene carbonate and propylene carbonate as an electrolytic salt at 1 mol%.
An organic electrolyte solution in which LiPF ₆ was dissolved was dropped to prepare a lithium secondary battery.

The charge / discharge cycle experiment was carried out between a charge of 4.2 V and a discharge of 3.0 V under a constant current condition of 8.6 mA. The results of the cycle life are shown in Table 4. Even after 500 cycles, no internal short circuit occurred and no reduction in capacity was observed.

[0105]

[Table 4]

(Examples 4-2 to 4-10) Experiments were conducted with the same configuration as in Example 4-1 and changing the composition and ionic conduction characteristics of the inorganic solid electrolyte. The cycle characteristics of this battery were investigated under the following conditions. In addition, for the addition of nitrogen atoms and adjustment of the content in the inorganic solid electrolyte thin film,
The adjustment was performed by adjusting the nitrogen gas concentration in the introduced gas in the RF magnetron sputtering method. Table 4 shows the results.

(Comparative Example 4-1 to Comparative Example 4-5) As a comparative experiment, the same configuration as in Example 4-1 was used except that a lithium metal having no solid electrolyte layer was used as a negative electrode. A charge / discharge experiment was performed with the configuration described above. The results are shown in Comparative Example 4-1 of Table 4. From the beginning of charging and discharging, the current efficiency was as low as 90% or more, and after 78 cycles, a voltage drop caused by a small internal short circuit began to be seen, and the capacity further decreased significantly .

In addition, similar experiments were conducted for batteries having different compositions of the inorganic solid electrolyte and ionic conduction characteristics.
The cycle characteristics of the battery were investigated. The results are similarly shown in Table 4. It can be seen that Comparative Examples 4-2 to 4-5 also have low cycle characteristics.

(Examples 4-11 to 4-15) An experiment was conducted by changing the thickness of the inorganic solid electrolyte thin film in the same configuration and the inorganic solid electrolyte composition as in Example 4-1. Was investigated for cycle characteristics. Table 5 shows the results. As long as the thickness of the solid electrolyte layer was in the range from 50 nm to 50 μm, no internal short-circuit occurred even after 500 cycles, and no reduction in capacity was observed.

[0110]

[Table 5]

(Comparative Example 4-6 to Comparative Example 4-8) The same experiment as in Example 4-1 was performed, except that the thickness of the inorganic solid electrolyte layer was changed except for the thickness of the inorganic solid electrolyte layer. The cycle characteristics of the battery were investigated. Table 5 shows the results. When the thickness of Comparative Example 8 was 60 μm, the current efficiency was insufficient at about 95% from the beginning of the charge / discharge cycle.
There was no change in its performance after 0 cycles.

(Examples 4-16 to 4-18) The inorganic solid electrolyte layer was formed into a two-layer structure, and the composition of the positive electrode side layer of the amorphous inorganic solid electrolyte layer was changed. The stability under was investigated. Further, with the same configuration as the battery described in Example 4-1, the battery characteristics were also investigated. The composition of the inorganic solid electrolyte layer on the negative electrode side was the same as that of Example 4-7. The thicknesses of the positive electrode side layer and the negative electrode side layer are 50 nm and 1 μm, respectively. Table 6 shows the results. In each case, extremely high stability is shown. Also, the battery characteristics showed the expected battery performance, no internal short circuit occurred even after 500 cycles, and no reduction in capacity was observed.

[0113]

[Table 6]

(Comparative Examples 4-9 to 4-10) The inorganic solid electrolyte layer was made into a two-layer structure, and the composition of the positive electrode side layer in the amorphous inorganic solid electrolyte layer was the same as in Examples 4-16 to 18-18. Alternately, the stability of the inorganic solid electrolyte in air was investigated. Further, the battery characteristics were also investigated with the same configuration as the battery described in Example 4-1. The composition of the inorganic solid electrolyte on the negative electrode side was the same as that of Example 4-7. Table 6 shows the results. In each of these cases, it became extremely unstable, and the battery characteristics were significantly reduced.

(Examples 4-19 to 4-20) The stability of the inorganic solid electrolyte in the air was investigated by changing the thickness of the solid electrolyte layer on the positive electrode side in the two inorganic solid electrolyte layers. Further, with the same configuration as in Example 4-16, the battery characteristics were examined. The composition of the inorganic solid electrolyte on the negative electrode side was the same as that of Example 4-7. Table 7 shows the results. In each of these cases, extremely high stability was exhibited. Also, the battery characteristics showed the expected battery performance, no internal short circuit occurred even after 500 cycles, and no reduction in capacity was observed.

[0116]

[Table 7]

(Comparative Examples 4-11 to 4-12) As comparative examples, the inorganic solid electrolyte layer was formed into a two-layer structure, and
The stability of the inorganic solid electrolyte in the air was investigated by changing the thickness of the amorphous inorganic solid electrolyte layer on the positive electrode side from 20. Further, with the same configuration as in Example 4-16, the battery characteristics were also investigated. The composition of the inorganic solid electrolyte layer on the negative electrode side was the same as that of Example 4-7. Table 7 shows the results. In each of these cases, it became extremely unstable, and the battery performance was significantly reduced.

(Example 4-21) The lithium metal surface of the negative electrode was once pre-sputtered in an argon gas atmosphere in an RF magnetron sputtering apparatus to remove an oxide layer inevitably on the lithium metal surface. did. Thereafter, an inorganic solid electrolyte thin film was formed on the surface. The composition of the electrolyte layer is as follows: Li: 39.4 at%, P: 0.3 at%, B: 16.0 at%, S: 43.3 at%, O: 1.1 at%, and the film thickness is 2.5 μm. Using the negative electrode, a lithium secondary battery was manufactured in the same configuration as in Example 1, and the cycle characteristics of the battery were investigated. The cycle test was performed under the constant current condition of 17.2 mA, but even after 500 cycles, no internal short circuit occurred.
No decrease in capacity was observed.

(Example 4-22) The lithium metal surface of the negative electrode was once pre-sputtered in an RF magnetron sputtering apparatus in an atmosphere containing H ₂ S, and an oxide unavoidably present on the surface was pre-sputtered. At the same time as removing the layer, a lithium sulfide layer was formed. Thereafter, an inorganic solid electrolyte thin film was formed on the surface. The composition of this electrolyte layer is as follows: Li: 38.2 at%, P: 12.2 at%, S: 48.6 at%, O: 1.0 at%, and film thickness: 10 μm. Using the negative electrode, a lithium secondary battery was fabricated in the same configuration as in Example 4-1 and the cycle characteristics of the battery were investigated. The cycle test was performed under a constant current condition of 17.2 mA. However, even after 500 cycles, no internal short circuit occurred and no reduction in capacity was observed.

(Example 4-23) The lithium metal surface of the negative electrode was once pre-sputtered in an N ₂ atmosphere in an RF magnetron sputtering apparatus to remove an oxide layer inevitably existing on the surface. At the same time, a lithium nitride layer was formed. Thereafter, an inorganic solid electrolyte thin film was formed on the surface. The composition of this electrolyte layer is as follows: Li: 42.3 atomic%, P: 0.
3 atomic%, Si: 11.8 atomic%, S: 44.3 atomic%, O: 1.3 atomic%, and the film thickness is 1 μm. Example 4 using the negative electrode
A lithium secondary battery was fabricated with the same configuration as that of -1, and the cycle characteristics of the battery were investigated. The cycle test is 17.2
The test was performed under the constant current condition of mA. However, even after 500 cycles, no internal short circuit occurred and no reduction in capacity was observed.

[0121]

As described above, according to the present invention,
A short circuit due to generation of dendrites from the lithium metal negative electrode can be suppressed, and a lithium secondary battery having high energy density, excellent charge / discharge cycle characteristics, and high stability and safety can be obtained.

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[Procedure amendment]

[Submission date] June 28, 2000 (2006.2.
8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H003 AA02 AA04 BB02 BB03 BC05 5H014 AA02 EE01 HH01 5H029 AJ03 AJ05 AJ12 AK16 AL01 AL12 AM12 DJ09 EJ03 HJ02 HJ04 HJ20

Claims (33)

[Claims] 1. A lithium secondary battery including an electrolyte layer, a positive electrode, and a negative electrode made of a lithium-containing material, wherein the electrolyte layer is made of an inorganic solid electrolyte, and the positive electrode contains an organic polymer. A rechargeable lithium battery. 2. A lithium ion conductivity at 25 ° C. of the electrolyte layer, 1 × 10 ^{- 5} lithium secondary battery according to claim 1, characterized in that ^S / cm or more. 3. A lithium ion conductivity at 25 ° C. of the electrolyte layer, 5 × 10 ^{- 4} A rechargeable lithium battery according to claim 1, characterized in that ^S / cm or more. 4. The lithium secondary battery according to claim 1, wherein the electrolyte layer is an amorphous body. 5. The lithium secondary battery according to claim 1, wherein the component of the electrolyte layer includes at least one selected from the group consisting of oxygen, nitrogen, sulfide, and oxynitride. 6. The sulfide is Li ₂ S, and Li ₂ S and SiS ₂ , Ge
A compound of at least one selected from the group consisting of S _2, Ga ₂ S _{3, oxynitride, Li 3 PO 4-X N} 2X / 3, Li 4 SiO 4-X N 2X / 3, Li ₄ GeO
_4-X N _{2X / 3} (0 <X <4) and Li ₃ BO _3-X N _{2X / 3} (0 <X <
The lithium secondary battery according to claim 5, wherein the lithium secondary battery is at least one selected from the group consisting of (3). 7. The lithium secondary battery according to claim 1, wherein the electrolyte layer contains the following components. A: Li component of 30 atomic% or more and 65 atomic% or less B: One or more elements selected from the group consisting of phosphorus, silicon, boron, germanium, and gallium C: sulfur 8. The lithium secondary battery according to claim 7, wherein the electrolyte layer further contains at least one of oxygen and nitrogen. 9. The lithium secondary battery according to claim 1, wherein the thickness of the electrolyte layer is 50 nm or more and 50 μm or less. 10. An electrolyte layer comprising a positive electrode side layer and a negative electrode side layer.
The lithium secondary battery according to claim 1, comprising a layer. 11. The negative electrode side layer is a thin film of a lithium ion conductive compound containing a sulfide, and the positive electrode side layer is a thin film of a lithium ion conductive compound containing an oxide. 4. The lithium secondary battery according to 1. 12. A two-layer electrolyte layer having a thickness of 2 μm
The lithium secondary battery according to claim 10, wherein the thickness is not less than 22 µm and the thickness of the positive electrode side layer is not less than 0.1 µm and not more than 2 µm. 13. The lithium secondary battery according to claim 10, wherein the negative electrode side layer contains lithium sulfide and silicon sulfide, and the positive electrode side layer contains at least one of a phosphate compound and a titanate compound. . 14. The lithium secondary battery according to claim 10, wherein the positive electrode side layer contains the following components. A: Li component of 30 atomic% or more and 50 atomic% or less B: phosphorus C: at least one of oxygen and nitrogen 15. The thickness of the positive electrode side layer is one of the thickness of the negative electrode side layer.
The lithium secondary battery according to claim 10, wherein the content is not less than 50% and not more than 50%. 16. The lithium secondary battery according to claim 10, wherein the thickness of the positive electrode side layer is 10 nm or more and 25 μm or less. 17. The lithium secondary battery according to claim 1, wherein the positive electrode further contains lithium ion conductive solid electrolyte particles, and the ion conductivity of the electrolyte particles is 10 ⁻³ S / cm or more. . 18. The lithium secondary battery according to claim 1, wherein the organic polymer of the positive electrode is a polysulfide-containing disulfide polymer. 19. The organic polymer of the positive electrode comprises LiPF ₆ and LiC
The lithium secondary battery according to claim 1, characterized by containing one of the lithium salt of F ₃ SO _3. 20. The lithium secondary battery according to claim 1, wherein the positive electrode contains an organic electrolyte. 21. The lithium secondary battery according to claim 21, wherein the lithium ion conductivity of the organic electrolyte of the positive electrode is lower than the lithium ion conductivity of the inorganic solid electrolyte of the electrolyte layer. 22. The method according to claim 20, wherein the organic electrolyte of the positive electrode contacts the lithium-containing material of the negative electrode, so that the ionic conductivity of the organic electrolyte is lower than the ionic conductivity of the inorganic solid electrolyte in the vicinity of the contact portion. Item 21. The lithium secondary battery according to Item 21. 23. The lithium secondary battery according to claim 21, wherein the organic solvent component in the organic electrolytic solution of the positive electrode contacts the lithium-containing material of the negative electrode to gasify in the vicinity of the contact portion. 24. The lithium secondary battery according to claim 21, wherein the organic solvent component in the organic electrolyte of the positive electrode contacts the lithium-containing material of the negative electrode, thereby solidifying in the vicinity of the contact portion. 25. The method according to claim 21, wherein the organic solvent component in the organic electrolyte of the positive electrode comes into contact with the lithium-containing material of the negative electrode, thereby increasing the viscosity of the organic electrolyte near the contact portion. Lithium secondary battery. 26. The lithium secondary battery according to claim 21, wherein the organic solvent component in the organic electrolyte of the positive electrode contains a sulfolane compound. 27. The lithium secondary battery according to claim 21, wherein the organic solvent component in the organic electrolyte of the positive electrode contains a chain carboxylic acid ester. 28. The lithium secondary battery according to claim 21, wherein the organic solvent component in the organic electrolyte of the positive electrode contains at least one of a compound having a nitrile group and a compound having an olefin bond. Next battery. 29. The lithium secondary battery according to claim 1, wherein the negative electrode has a surface roughness of 0.01 to 5 μm in Rmax value. 30. The lithium secondary battery according to claim 1, wherein a metal layer forming an alloy or an intermetallic compound with lithium is formed on the electrolyte layer side of the negative electrode, and the negative electrode has a multilayer or gradient composition. Next battery. 31. The lithium secondary battery according to claim 1, wherein the negative electrode has no oxide layer on the surface and has a sulfide layer or a nitride layer on the surface. 32. The lithium secondary battery according to claim 1, wherein an electrolyte layer is formed directly on the surface of the negative electrode without an intervening oxide layer. 33. The method according to claim 1, wherein a current collector is provided on each of the positive and negative electrodes, and an electrolyte layer is formed directly on the current collector of the negative electrode without providing a lithium-containing material on the negative electrode. The lithium secondary battery according to the above.