CN114026727B

CN114026727B - All-solid-state lithium secondary battery and method for manufacturing all-solid-state lithium secondary battery

Info

Publication number: CN114026727B
Application number: CN202080047305.1A
Authority: CN
Inventors: 佐藤一; 朴甲相; 上田博幸
Original assignee: Dell Japan Co ltd
Current assignee: Dell Japan Co ltd
Priority date: 2019-10-15
Filing date: 2020-10-13
Publication date: 2024-05-07
Anticipated expiration: 2040-10-13
Also published as: JPWO2021075420A1; JP7275300B2; WO2021075420A1; CN114026727A

Abstract

An all-solid-state lithium secondary battery (1) is provided with: an oxide solid electrolyte layer (11) containing oxide solid electrolyte particles (11 a) having lithium ion conductivity, a positive electrode active material layer (13) disposed on one surface side of the oxide solid electrolyte layer (11), a negative electrode active material layer (16) disposed on the other surface side of the oxide solid electrolyte layer (11), and a solid electrolyte dispersion polymer layer disposed between the oxide solid electrolyte layer (11) and at least one of the positive electrode active material layer (13) and the negative electrode active material layer (16), wherein the oxide solid electrolyte particles are dispersed in a lithium ion conductive polymer material having lithium ion conductivity; the positive electrode active material layer (13), the negative electrode active material layer (16), the solid electrolyte dispersion polymer layer, and the oxide solid electrolyte layer (11) are integrally formed.

Description

All-solid-state lithium secondary battery and method for manufacturing all-solid-state lithium secondary battery

Technical Field

The present invention relates to an all-solid-state lithium secondary battery and a method for manufacturing the same.

Background

In general, lithium ion batteries using nonaqueous electrolytes are popular. However, since the lithium ion battery is flammable in the electrolyte, there is a risk of ignition or the like, or an organic solvent is used, and thus there is a limit in the use temperature. Accordingly, an all-solid lithium secondary battery using a polymer electrolyte is being developed. However, the polymer electrolyte has low ionic conductivity at low temperature, and the use temperature range is narrower than that of a lithium ion battery using the above nonaqueous electrolyte. Accordingly, an all-solid lithium secondary battery using a sulfide-based solid state electrolyte is being developed. However, the reaction of sulfides with water may produce hydrogen sulfide, so the range of use temperatures is limited. Therefore, it is desired to develop an all-solid-state battery using an oxide-based solid-state electrolyte, which can compensate for such drawbacks of polymer electrolytes and sulfide-based electrolytes.

For example, patent document 1 below describes an all-solid-state lithium secondary battery as follows: the lithium ion secondary battery is formed by sandwiching a composite solid electrolyte layer having lithium ion conductive oxide particles and lithium ion conductive amorphous portions interposed between the oxide particles between a positive electrode having a positive electrode active material and a negative electrode having a negative electrode active material.

Patent document 2 describes a solid electrolyte for an all-solid lithium ion secondary battery using an oxide solid electrolyte. In the solid electrolyte, an adhesive layer having lithium ion conductivity is provided on the surface of the solid electrolyte body for the purpose of reducing the resistance of the interface between the solid electrolyte body and the electrode.

Patent document 1: japanese patent application laid-open No. 2015-138741

Patent document 2: japanese patent laid-open publication No. 2017-069036

Disclosure of Invention

An all-solid-state lithium secondary battery using the oxide solid-state electrolyte as described in patent document 1 is difficult to produce hydrogen sulfide by reaction with water and is easy to handle, but has higher internal resistance and lower conductivity than an all-solid-state lithium secondary battery using the sulfide electrolyte.

In addition, the adhesive layer of the solid electrolyte described in patent document 2 is preferably as thin as possible because the ionic conductivity (ionic conductance) is one order of magnitude lower than that of the solid electrolyte body. However, if the adhesive layer is thinned, the gap between the electrode and the solid electrolyte body may not be filled, and instead, the internal resistance may be increased.

Therefore, in all-solid-state lithium secondary batteries using an oxide solid-state electrolyte that is easy to handle, it is desirable to reduce the internal resistance and realize a large current.

Accordingly, an object of the present invention is to provide an all-solid-state lithium secondary battery which is easy to handle and can realize a large current, and a method for manufacturing the all-solid-state lithium secondary battery.

In order to solve the above problems, an all-solid-state lithium secondary battery according to the present invention includes: an oxide solid electrolyte layer including oxide solid electrolyte particles having lithium ion conductivity, a positive electrode active material layer disposed on one surface side of the oxide solid electrolyte layer, a negative electrode active material layer disposed on the other surface side of the oxide solid electrolyte layer, and a solid electrolyte dispersion polymer layer disposed between the oxide solid electrolyte layer and at least one of the positive electrode active material layer and the negative electrode active material layer, wherein the solid electrolyte dispersion polymer layer is formed by dispersing the oxide solid electrolyte particles in a lithium ion conductive polymer material having lithium ion conductivity; the positive electrode active material layer, the negative electrode active material layer, the solid electrolyte dispersion polymer layer, and the oxide solid electrolyte layer are integrally formed.

Unlike the above sulfides, oxides do not generate gases that require attention in terms of handling, such as hydrogen sulfide, even if they react with water. Therefore, the all-solid lithium secondary battery of the present invention using the oxide solid electrolyte is easy to handle.

In the present specification, the state in which the layers are integrally formed means a state in which the layers cannot be peeled off and are broken when forced peeling is required. Therefore, in the all-solid-state lithium secondary battery of the present invention, the positive electrode active material layer, the negative electrode active material layer, the solid electrolyte dispersion polymer layer, and the oxide solid electrolyte layer are in a state of being unable to be peeled off. As described above, the resistance between the cathode active material layer, the anode active material layer, the solid electrolyte dispersion polymer layer, and the oxide solid electrolyte layer, which are integrated, is lower than the resistance between the cathode active material layer, the anode active material layer, the solid electrolyte dispersion polymer layer, and the oxide solid electrolyte layer, which are simply and adjacently arranged without being integrated.

In the all-solid-state lithium secondary battery of the present invention, the solid electrolyte dispersion polymer layer contains a lithium ion conductive polymer material having lithium ion conductivity and oxide solid electrolyte particles dispersed in the material. In general, since the lithium ion conductivity of the oxide solid electrolyte particles is higher than that of the lithium ion conductive polymer material, the ion conductivity of the solid electrolyte dispersion polymer layer is higher than that of a layer composed only of the lithium ion conductive polymer material, such as the adhesive layer of patent document 2. Therefore, the solid electrolyte dispersion polymer layer of the present invention can be formed thicker than the adhesive layer of patent document 2, which is made of only lithium ion conductive polymer material. Therefore, it is possible to suppress a situation in which the gap between the electrode and the solid electrolyte body cannot be filled up and the internal resistance becomes high, as in the adhesive layer of patent document 2. Therefore, according to the all-solid-state lithium secondary battery of the present invention, the internal resistance is reduced, and a large current can be realized.

The method for manufacturing an all-solid-state lithium secondary battery according to the present invention is characterized by comprising: a disposing step of disposing the oxide solid electrolyte layer, the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte dispersion polymer layer in the following manner: the positive electrode active material layer is disposed on one surface side of an oxide solid electrolyte layer containing oxide solid electrolyte particles and having lithium ion conductivity, the negative electrode active material layer is disposed on the other surface side of the oxide solid electrolyte layer, and the solid electrolyte dispersion polymer layer is disposed between the oxide solid electrolyte layer and at least one of the positive electrode active material layer and the negative electrode active material layer, the solid electrolyte dispersion polymer layer is formed by dispersing the oxide solid electrolyte particles in a lithium ion conductive polymer material having lithium ion conductivity, and the positive electrode active material layer, the negative electrode active material layer, the solid electrolyte dispersion polymer layer, and the oxide solid electrolyte layer are integrated in an integrating step.

According to the method for manufacturing an all-solid lithium secondary battery, the internal resistance is reduced by using an oxide solid electrolyte which is easy to handle, and an all-solid lithium secondary battery which can realize large current can be manufactured.

As described above, according to the present invention, an all-solid-state lithium secondary battery that is easy to handle and can realize large current, and a method for manufacturing the all-solid-state lithium secondary battery can be provided.

Drawings

Fig. 1 is a view showing a cross-sectional view of an all-solid lithium secondary battery according to an embodiment of the present invention.

Fig. 2 is an enlarged view of fig. 1 from the positive electrode active material layer to the oxide solid electrolyte layer.

Fig. 3 is an enlarged view of the anode active material layer to the oxide solid electrolyte layer in fig. 1.

Fig. 4 is a flowchart of a method of manufacturing an all-solid lithium secondary battery according to an embodiment of the present invention.

Fig. 5 is a diagram showing a form of the preparation step.

Fig. 6 is a diagram showing a configuration of the arrangement process.

Fig. 7 is a diagram showing a mode of the integration process.

FIG. 8 is a Cole plot (Cole-Cole plot) showing the measurement results of the examples.

Detailed Description

Hereinafter, preferred embodiments of the all-solid lithium secondary battery and the method for manufacturing the all-solid lithium secondary battery according to the present invention will be described in detail with reference to the accompanying drawings. The following exemplary embodiments are provided to facilitate understanding of the present invention, and are not intended to limit the present invention. The present invention is capable of modification and improvement without departing from the spirit thereof. In addition, some of the drawings are exaggerated in order to facilitate understanding.

Fig. 1 is a view showing a cross-sectional view of an all-solid lithium secondary battery according to an embodiment of the present invention. As shown in fig. 1, an all-solid lithium secondary battery 1 according to the present embodiment has a battery body 1b disposed in a packaging material 10. The battery body 1b has an oxide solid-state electrolyte layer 11, a positive-side solid-state electrolyte dispersion polymer layer 12, a positive electrode active material layer 13, a positive electrode current collector layer 14, a negative-side solid-state electrolyte dispersion polymer layer 15, a negative electrode active material layer 16, and a negative electrode current collector layer 17 as main structures.

< Oxide solid electrolyte layer >)

Fig. 2 is an enlarged view from the positive electrode active material layer 13 to the oxide solid electrolyte layer 11 in fig. 1. As shown in fig. 2, the oxide solid electrolyte layer 11 has the following structure: at least a part of the lithium ion conductive polymer material 11b enters between the particles of the oxide solid electrolyte particles 11a, that is, at least a part of the lithium ion conductive polymer material 11b is disposed between the particles of the oxide solid electrolyte particles 11 a.

The oxide solid electrolyte constituting the oxide solid electrolyte particles 11a is not particularly limited as long as it is an oxide solid electrolyte having lithium ion conductivity, but examples thereof include Lithium Aluminum Titanium Phosphate (LATP), lithium Lanthanum Zirconium Oxide (LLZO), lithium Lanthanum Titanium Oxide (LLTO), and Lithium Aluminum Germanium Phosphate (LAGP). Further, silicon (Si) and germanium (Ge) may be added to the LATP.

The average particle diameter of the oxide solid electrolyte particles 11a is, for example, 0.1 μm or more and 5 μm or less. In the present specification, the particle diameter refers to an average particle diameter measured by a 1090L-type laser diffraction particle diameter distribution measuring apparatus manufactured by CILAS corporation, for example.

The lithium ion conductive polymer material 11b interposed between the particles of the oxide solid electrolyte particles 11a has lithium ion conductivity. As such a lithium ion conductive polymer material 11b, a polymer material having lithium ion conductivity can be cited. Examples of such polymer materials include polyethylene oxide (PEO), polyethylene glycol (PEG), and polyvinylidene fluoride (PVDF). The lithium ion conductive polymer material 11b may be a polymer containing a lithium salt. That is, the polymer does not have lithium ion conductivity, and the polymer contains a lithium salt as a supporting salt (supporting electrolyte: supporting electrolyte), thereby having lithium ion conductivity. Examples of such lithium salts include lithium hexafluorophosphate (LiPF ₆), lithium borofluoride (LiBF ₄), lithium bis (oxalato) borate (LiBOB), lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), and lithium bis (fluorosulfonyl) imide (LiFSI). Further, a polymer having lithium ion conductivity such as PEO, PEG, PVDF may have a lithium salt-containing structure. Further, it is preferable that lithium ion conductive oxide solid electrolyte particles are mixed with a polymer having lithium ion conductivity. As the oxide solid-state electrolyte particles in this case, particles similar to those of the oxide solid-state electrolyte that can be used for the oxide solid-state electrolyte particles 11a can be cited. In particular, since lithium ion conductive oxides such as LATP and LLZO tend to have a high lithium ion conductive polymer ion conductivity, lithium ion conductivity can be further increased by mixing.

As described above, the oxide solid electrolyte layer 11 according to the present embodiment is configured such that the lithium ion conductive polymer material 11b is interposed between the oxide solid electrolyte particles 11a, and therefore, compared with a case where the oxide solid electrolyte layer 11 is configured only by the oxide solid electrolyte particles 11a, the lithium ion conductive polymer material 11b is not interposed between the oxide solid electrolyte particles 11a, the resistance can be reduced. The oxide solid electrolyte layer 11 of this structure is sometimes referred to as a composite solid electrolyte layer.

< Positive electrode active material layer >)

The positive electrode active material layer 13 of the present embodiment has a structure in which a lithium ion conductive polymer material 13b enters between the positive electrode active materials 13a, and has lithium ion conductivity.

The material constituting the positive electrode active material 13a is not particularly limited as long as it contains lithium and can absorb and release lithium ions, and examples thereof include Lithium Manganate (LMO), lithium Cobaltate (LCO), lithium Nickelate (LNO), ternary system (NMC or NCA), lithium iron phosphate (LFP), vanadium phosphate oxide (LVP), cobalt manganese phosphate oxide (LCMP), and mixtures thereof. The ternary element as referred to herein means a material containing, for example, nickel, manganese, or aluminum, cobalt.

The lithium ion conductive polymer material 13b that enters between the positive electrode active materials 13a is the same as that which can be used for the lithium ion conductive polymer material 11 b. In the present embodiment, the lithium ion conductive polymer material 13b that enters between the positive electrode active materials 13a and the lithium ion conductive polymer material 11b that enters between the particles of the oxide solid electrolyte particles 11a may be the same material or may be different materials.

In addition, a conductive auxiliary agent such as acetylene black may be dispersed in the lithium ion conductive polymer material 13b of the positive electrode active material layer 13.

< Positive electrode side solid electrolyte dispersed Polymer layer >)

In the present embodiment, a positive electrode side solid electrolyte dispersion polymer layer 12, which is a solid electrolyte dispersion polymer layer in which oxide solid electrolyte particles 12a are dispersed in a lithium ion conductive polymer material 12b, is sandwiched between a positive electrode active material layer 13 and an oxide solid electrolyte layer 11. The lithium ion conductive polymer material 12b constituting the positive electrode side solid electrolyte dispersion polymer layer 12 is the same as the lithium ion conductive polymer material 11b that can be used for the oxide solid electrolyte layer 11.

The oxide solid electrolyte of the oxide solid electrolyte particles 12a constituting the positive electrode side solid electrolyte dispersion polymer layer 12 may be the same as the oxide solid electrolyte of the oxide solid electrolyte particles 11a that can be used for the oxide solid electrolyte layer 11. Further, from the viewpoint of reducing contact resistance, it is preferable that the oxide solid electrolyte particles 12a of the positive electrode side solid electrolyte dispersion polymer layer 12 and the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11 are composed of the same oxide solid electrolyte. The oxide solid electrolyte particles 12a of the positive electrode side solid electrolyte dispersion polymer layer 12 and the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11 may be composed of oxide solid electrolytes different from each other. In this case, for example, LAGP and LLZO are used as the oxide solid electrolytes of the oxide solid electrolyte particles 11a constituting the oxide solid electrolyte layer 11, and LATP is used as the oxide solid electrolytes of the oxide solid electrolyte particles 12a constituting the positive electrode side solid electrolyte dispersion polymer layer 12. If the combination is used, the reduction resistance of the oxide solid electrolyte can be improved.

The particle diameter of the oxide solid electrolyte particles 12a of the positive electrode side solid electrolyte dispersion polymer layer 12 may be the same as the particle diameter of the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11. In this case, the average particle diameter of the oxide solid electrolyte particles 12a is, for example, 0.1 μm or more and 5 μm or less. However, the particle diameter of the oxide solid electrolyte particles 12a of the positive electrode side solid electrolyte dispersion polymer layer 12 may be different from the particle diameter of the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11. For example, if the particle size of the oxide solid electrolyte particles 12a of the positive electrode side solid electrolyte dispersion polymer layer 12 is smaller than the particle size of the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11, the positive electrode side solid electrolyte dispersion polymer layer 12 can be thinned, which is preferable because it contributes to the low resistance of the all-solid-state lithium secondary battery 1. As will be described later, when the positive electrode side solid electrolyte dispersion polymer layer 12 is formed by coating, the oxide solid electrolyte particles 12a and the lithium ion conductive polymer material 12b can be made to enter between the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11. However, the particle diameter of the oxide solid electrolyte particles 12a of the positive electrode side solid electrolyte dispersion polymer layer 12 may be larger than the particle diameter of the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11.

Further, the average thickness of the positive electrode side solid electrolyte dispersion polymer layer 12 may be smaller than the particle diameter of the oxide solid electrolyte particles 12 a. In this case, the positive electrode side solid electrolyte dispersion polymer layer 12 becomes thicker at the portion where the oxide solid electrolyte particles 12a are located and becomes thinner at the portion where the oxide solid electrolyte particles 12a are not present. Therefore, the oxide solid electrolyte particles 12a are easily brought into contact with the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11 and the positive electrode active material 13 a.

In the positive electrode side solid electrolyte dispersion polymer layer 12, the volume ratio of the oxide solid electrolyte particles 12a is preferably larger than the volume ratio of the lithium ion conductive polymer material 12 b. In this way, the resistance of the positive electrode side solid electrolyte dispersion polymer layer 12 can be made smaller.

In the present embodiment, the oxide solid electrolyte layer 11 and the positive electrode side solid electrolyte dispersion polymer layer 12 are formed integrally, and further, the positive electrode active material layer 13 and the positive electrode side solid electrolyte dispersion polymer layer 12 are formed integrally, and therefore, the oxide solid electrolyte layer 11 and the positive electrode active material layer 13 are formed integrally by the positive electrode side solid electrolyte dispersion polymer layer 12. Therefore, when the oxide solid electrolyte layer 11 and the positive electrode active material layer 13 are peeled off, the battery structure is broken.

In addition, from the viewpoint of improving the strength of integration of the positive electrode side solid electrolyte dispersion polymer layer 12 and the oxide solid electrolyte layer 11, it is preferable that the lithium ion conductive polymer material 15b constituting the positive electrode side solid electrolyte dispersion polymer layer 12 and the lithium ion conductive polymer material 11b interposed between the oxide solid electrolyte particles 11a are the same material as each other. In addition, this case is also preferable in that the positive electrode side solid electrolyte dispersion polymer layer 12 and the lithium ion conductive polymer material 11b interposed between the oxide solid electrolyte particles 11a can be formed simultaneously by coating. However, the lithium ion conductive polymer material 12b of the positive electrode side solid state electrolyte dispersion polymer layer 12 and the lithium ion conductive polymer material 11b that enters between the oxide solid state electrolyte particles 11a may be provided with the positive electrode side solid state electrolyte dispersion polymer layer 12 on the surface of the positive electrode side of the oxide solid state electrolyte layer 11 in a state where the lithium ion conductive polymer material 11b enters between the oxide solid state electrolyte particles 11a, even though they are the same material as each other. The lithium ion conductive polymer material constituting the positive electrode side solid electrolyte dispersion polymer layer 12 and the lithium ion conductive polymer material 11b interposed between the oxide solid electrolyte particles 11a may be different materials from each other. In this case, for example, PVDF is preferably used as the lithium ion conductive polymer material constituting the positive electrode side solid electrolyte dispersion polymer layer 12, and PEO is preferably used as the lithium ion conductive polymer material 11b interposed between the oxide solid electrolyte particles 11 a. In such a combination, PVDF, which is more difficult to decompose than PEO, is used on the high potential side, so that the battery voltage can be increased. Therefore, the high-potential and high-energy of the all-solid-state lithium secondary battery 1 can be facilitated.

In addition, from the viewpoint of improving the strength of integration of the positive electrode side solid electrolyte dispersion polymer layer 12 and the positive electrode active material layer 13, it is preferable that the lithium ion conductive polymer material constituting the positive electrode side solid electrolyte dispersion polymer layer 12 and the lithium ion conductive polymer material 13b interposed between the positive electrode active materials 13a are the same material as each other. The lithium ion conductive polymer material constituting the positive electrode side solid electrolyte dispersion polymer layer 12 and the lithium ion conductive polymer material 13b interposed between the positive electrode active materials 13a may be materials that are not used for each other. In this case, for example, PEO is preferably used as the lithium ion conductive polymer material 12b constituting the positive electrode side solid electrolyte dispersion polymer layer 12, and PVDF is preferably used as the lithium ion conductive polymer material 13b interposed between the positive electrode active materials 13 a. In such a combination, PVDF, which is more difficult to decompose than PEO, is used on the high potential side, so that the battery voltage can be increased. Therefore, the high-potential and high-energy of the all-solid-state lithium secondary battery 1 can be facilitated.

< Positive electrode collector layer >)

The positive electrode collector layer 14 is disposed on the surface side of the positive electrode active material layer 13 opposite to the side of the oxide solid electrolyte layer 11, and is formed integrally with the positive electrode active material layer 13. The positive electrode collector layer 14 is made of a conductive and nonionic conductive material. Examples of such a material include a metal and a carbon sheet, and examples of such a metal include copper, aluminum, and an iron-nickel alloy.

< Negative electrode active material layer >)

Fig. 3 is an enlarged view from the anode active material layer 16 to the oxide solid electrolyte layer 11 in fig. 1. The negative electrode active material layer 16 of the present embodiment has a structure in which the lithium ion conductive polymer material 16b enters between the negative electrode active materials 16a, and has lithium ion conductivity.

The material constituting the negative electrode active material 16a is not particularly limited as long as it can absorb and release lithium ions, and examples thereof include easily graphitizable carbon, hard graphitizable carbon, LTO, LMO, si, li, and mixtures thereof.

As the lithium ion conductive polymer material 16b that enters between the negative electrode active materials 16a, a material that can be used for the lithium ion conductive polymer material 11b can be cited. In the present embodiment, the lithium ion conductive polymer material 16b that enters between the negative electrode active materials 16a and the lithium ion conductive polymer material 11b that enters between the particles of the oxide solid electrolyte particles 11a may be the same material or may be different materials. The lithium ion conductive polymer material 16b interposed between the negative electrode active materials 16a and the lithium ion conductive polymer material 13b interposed between the positive electrode active materials 13a may be the same material or different materials.

In addition, a conductive auxiliary agent such as acetylene black may be dispersed in the lithium ion conductive polymer material 16b of the negative electrode active material layer 16.

< Cathode side solid electrolyte dispersed Polymer layer >)

In the present embodiment, the negative electrode side solid electrolyte dispersion polymer layer 15 is sandwiched between the negative electrode active material layer 16 and the oxide solid electrolyte layer 11, and the negative electrode side solid electrolyte dispersion polymer layer 15 is formed as a solid electrolyte dispersion polymer layer in which the oxide solid electrolyte particles 15a are dispersed in the lithium ion conductive polymer material 15 b. As the lithium ion conductive polymer material 15b constituting the negative electrode side solid electrolyte dispersion polymer layer 15, a material that can be used for the lithium ion conductive polymer material 11b can be cited.

The oxide solid electrolyte of the oxide solid electrolyte particles 15a constituting the negative electrode side solid electrolyte dispersion polymer layer 15 may be the same as the oxide solid electrolyte of the oxide solid electrolyte particles 11a that can be used for the oxide solid electrolyte layer 11. Further, from the viewpoint of reducing contact resistance, it is preferable that the oxide solid electrolyte particles 15a of the negative electrode side solid electrolyte dispersion polymer layer 15 and the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11 are composed of the same oxide solid electrolyte. The oxide solid electrolyte particles 15a of the negative electrode side solid electrolyte dispersion polymer layer 15 and the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11 may be composed of oxide solid electrolytes different from each other. In this case, for example, LATP is used in the oxide solid electrolyte constituting the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11, and LAGP and LLZO are used in the oxide solid electrolyte constituting the oxide solid electrolyte particles 15a of the negative electrode side solid electrolyte-dispersed polymer layer 15. In such a combination, the reduction resistance of the negative electrode can be improved.

In addition, the particle diameter of the oxide solid electrolyte particles 15a of the negative electrode side solid electrolyte dispersion polymer layer 15 may be the same as the particle diameter of the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11. However, the particle diameter of the oxide solid electrolyte particles 15a of the negative electrode side solid electrolyte dispersion polymer layer 15 may be different from the particle diameter of the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11. For example, if the particle size of the oxide solid electrolyte particles 15a of the negative electrode side solid electrolyte dispersion polymer layer 15 is smaller than the particle size of the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11, the negative electrode side solid electrolyte dispersion polymer layer 15 can be made thinner, and the low resistance of the all-solid lithium secondary battery 1 can be facilitated, which is preferable. In addition, when the negative electrode side solid electrolyte dispersion polymer layer 15 is formed by coating as will be described later, the oxide solid electrolyte particles 15a and the lithium ion conductive polymer material 15b can be made to enter between the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11 together. However, the particle diameter of the oxide solid electrolyte particles 15a of the negative electrode side solid electrolyte dispersion polymer layer 15 may be larger than the particle diameter of the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11.

The average thickness of the negative electrode side solid electrolyte dispersion polymer layer 15 may be smaller than the particle diameter of the oxide solid electrolyte particles 15 a. In this case, the negative electrode side solid electrolyte dispersion polymer layer 15 becomes thicker at the portion where the oxide solid electrolyte particles 15a are located and becomes thinner at the portion where the oxide solid electrolyte particles 15a are not present. Therefore, the oxide solid electrolyte particles 15a easily come into contact with the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11 and the positive electrode active material 13 a.

In the negative electrode side solid electrolyte dispersion polymer layer 15, the volume ratio of the oxide solid electrolyte particles 15a is preferably larger than the volume ratio of the lithium ion conductive polymer material 15 b. In this way, the resistance of the negative electrode side solid electrolyte dispersion polymer layer 15 can be made smaller.

In the present embodiment, the oxide solid electrolyte layer 11 and the negative electrode side solid electrolyte dispersion polymer layer 15 are formed integrally, and the negative electrode active material layer 16 and the negative electrode side solid electrolyte dispersion polymer layer 15 are formed integrally, so the oxide solid electrolyte layer 11 and the negative electrode active material layer 16 are formed integrally by the negative electrode side solid electrolyte dispersion polymer layer 15. Therefore, when the oxide solid electrolyte layer 11 and the anode active material layer 16 are peeled off, damage occurs.

In addition, from the viewpoint of improving the strength of integration of the anode-side solid electrolyte dispersion polymer layer 15 and the oxide solid electrolyte layer 11, it is preferable that the lithium ion conductive polymer material 15b constituting the anode-side solid electrolyte dispersion polymer layer 15 and the lithium ion conductive polymer material 11b interposed between the oxide solid electrolyte particles 11a are the same material as each other. In addition, this is also preferable from the viewpoint that the negative electrode side solid electrolyte dispersion polymer layer 15 and the lithium ion conductive polymer material 11b interposed between the oxide solid electrolyte particles 11a can be formed simultaneously by coating. However, the lithium ion conductive polymer material 15b of the negative electrode side solid electrolyte dispersion polymer layer 15 and the lithium ion conductive polymer material 11b interposed between the oxide solid electrolyte particles 11a may be provided with the negative electrode side solid electrolyte dispersion polymer layer 15 on the negative electrode side surface of the oxide solid electrolyte layer 11 in a state in which the lithium ion conductive polymer material 11b is interposed between the oxide solid electrolyte particles 11a, even if the materials are the same as each other. The lithium ion conductive polymer material constituting the negative electrode side solid electrolyte dispersion polymer layer 15 and the lithium ion conductive polymer material 11b interposed between the oxide solid electrolyte particles 11a may be different materials from each other. In this case, for example, PVDF, SBR, acrylic ester, or the like can be suitably used as the lithium ion conductive polymer material constituting the negative electrode side solid electrolyte dispersion polymer layer 15, and PEO can be used as the lithium ion conductive polymer material 11b interposed between the oxide solid electrolyte particles 11 a.

In addition, from the viewpoint of improving the strength of integration of the negative electrode side solid electrolyte dispersion polymer layer 15 and the negative electrode active material layer 16, it is preferable that the lithium ion conductive polymer material constituting the negative electrode side solid electrolyte dispersion polymer layer 15 and the lithium ion conductive polymer material 16b interposed between the negative electrode active materials 16a are the same material as each other. The lithium ion conductive polymer material constituting the negative electrode side solid electrolyte dispersion polymer layer 15 and the lithium ion conductive polymer material 16b interposed between the negative electrode active materials 16a may be different materials from each other. In this case, for example, PVDF is preferably used as the lithium ion conductive polymer material constituting the negative electrode side solid electrolyte dispersion polymer layer 15, and a mixture of PEO and PVDF is preferably used as the lithium ion conductive polymer material 13b interposed between the negative electrode active materials 16 a. In such a combination, the adhesion between the negative electrode side solid electrolyte dispersion polymer layer 15 and the negative electrode active material layer 16 can be improved.

< Negative electrode collector layer >)

The negative electrode current collector layer 17 is disposed on the surface side of the negative electrode active material layer 16 opposite to the side of the oxide solid electrolyte layer 11, and is formed integrally with the negative electrode active material layer 16. As a material of the negative electrode current collector layer 17, for example, the same material as the positive electrode current collector layer 14 can be cited.

< Packing Material >)

The packaging material 10 is a member that houses and seals the positive electrode current collector layer 14, the positive electrode active material layer 13, the positive electrode side solid electrolyte dispersion polymer layer 12, the oxide solid electrolyte layer 11, the negative electrode side solid electrolyte dispersion polymer layer 15, the negative electrode active material layer 16, and the negative electrode current collector layer 17. A part of the positive electrode collector layer 14 and the negative electrode collector layer 17 is led out of the package 10 as an electrode.

The structure of the package material 10 is not particularly limited as long as it can inhibit external oxygen, moisture, and the like from entering into the region surrounded by the package material 10 and from conducting with the region, and for example, a structure in which a metal foil such as aluminum is laminated on a resin layer can be used.

As described above, the all-solid-state lithium secondary battery 1 of the present embodiment uses the oxide solid electrolyte, and since the oxide is different from the sulfide, the gas requiring attention such as hydrogen sulfide is not generated even when it reacts with water, and thus the treatment is easy. In the all-solid-state lithium secondary battery 1 according to the present embodiment, the positive electrode active material layer 13, the negative electrode active material layer 16, the positive electrode side solid electrolyte dispersion polymer layer 12, the negative electrode side solid electrolyte dispersion polymer layer 15, and the oxide solid electrolyte layer 11 are integrated to such an extent that they cannot be peeled off. The resistance between the layers integrated in this way is lower than the resistance between the layers which are not integrated but simply arranged adjacently.

In the all-solid-state lithium secondary battery 1 of the present embodiment, the positive electrode side solid-state electrolyte dispersion polymer layer 12 interposed between the positive electrode current collector layer 14 and the oxide solid-state electrolyte layer 11 is formed by dispersing the oxide solid-state electrolyte particles 12a in the lithium ion conductive polymer material 12 b. In the all-solid-state lithium secondary battery 1 according to the present embodiment, the negative electrode side solid-state electrolyte dispersion polymer layer 15 interposed between the negative electrode active material layer 16 and the oxide solid-state electrolyte layer 11 is formed by dispersing the oxide solid-state electrolyte particles 15a in the lithium ion conductive polymer material 15 b. In general, since the oxide solid electrolyte particles have higher lithium ion conductivity than the lithium ion conductive polymer material, the positive electrode side solid electrolyte dispersion polymer layer 12 and the negative electrode side solid electrolyte dispersion polymer layer 15 have higher ion conductivity than the layer made of only the lithium ion conductive polymer material. Therefore, the positive electrode side solid electrolyte dispersion polymer layer 12 and the negative electrode side solid electrolyte dispersion polymer layer 15 of the present embodiment can be formed thicker than in the case where a layer made of only lithium ion conductive polymer material is disposed between the positive electrode active material layer 13 and the oxide solid electrolyte layer 11 and between the negative electrode active material layer 16 and the oxide solid electrolyte layer 11. Therefore, it is possible to suppress an increase in internal resistance due to the inability to fill the gaps between the positive electrode active material layer 13 and the negative electrode active material layer 16 and the oxide solid electrolyte layer 11.

As described above, according to the all-solid-state lithium secondary battery 1 of the present embodiment, the internal resistance can be reduced, and a large current can be realized.

Next, a method for manufacturing the all-solid lithium secondary battery 1 according to the present embodiment will be described.

Fig. 4 is a flowchart of a method for manufacturing the all-solid lithium secondary battery 1 according to the embodiment. As shown in fig. 4, the method for manufacturing the all-solid lithium secondary battery 1 according to the present embodiment includes a preparation step P1, an arrangement step P2, an integration step P3, and a sealing step P4.

< Preparation Process P1 >)

The present step is a step of mainly preparing the oxide solid electrolyte layer 11, the positive electrode active material layer 13, the positive electrode current collector layer 14, the negative electrode active material layer 16, and the negative electrode current collector layer 17. Fig. 5 is a diagram showing a form of the preparation step.

(Preparation of oxide solid electrolyte layer)

In the preparation of the oxide solid electrolyte layer 11, first, a green sheet (GREEN SHEET) in which the oxide solid electrolyte particles 11a are dispersed in a binder is prepared, and then, a porous sheet-like member that becomes the oxide solid electrolyte layer 11 in which the oxide solid electrolyte particles 11a are integrated with each other is obtained by firing. Alternatively, the oxide solid electrolyte particles 11a may be placed in a mold, and a porous sheet-like member to be the oxide solid electrolyte layer 11 may be obtained by firing the molded sheet-like member with a predetermined pressure applied thereto. Further alternatively, the oxide solid electrolyte particles 11a may be dispersed in a binder, and then molded into a sheet shape and the binder is cured. The binder may be made of the lithium ion conductive polymer material 11 b. Alternatively, the binder may not be composed of the lithium ion conductive polymer material 11b, but in the present embodiment, since the lithium ion conductive polymer material 11b is incorporated between the oxide solid electrolyte particles 11a, the amount of the binder in this case is such that voids can be formed between the oxide solid electrolyte particles 11 a. Thus, a sheet member containing the oxide solid electrolyte particles 11a was obtained.

Next, a dispersion liquid in which the oxide solid electrolyte particles are dispersed in the lithium ion conductive polymer material is applied to both surfaces of the sheet member containing the oxide solid electrolyte particles 11a and cured. At this time, the coated lithium ion conductive polymer material enters between the oxide solid electrolyte particles 11a, and becomes the lithium ion conductive polymer material 11b disposed between the oxide solid electrolyte particles 11 a. Thus, the lithium ion conductive polymer material 11b shown in fig. 5 is obtained to enter the oxide solid electrolyte layer 11 between the oxide solid electrolyte particles 11 a. In this case, it is more preferable that the oxide solid electrolyte particles in the dispersion liquid enter between the oxide solid electrolyte particles 11a from the viewpoint of lowering the resistance. In this case, as long as the particle diameter of the oxide solid electrolyte particles in the dispersion is smaller than the particle diameter of the oxide solid electrolyte particles 11a of the sheet-like member, the oxide solid electrolyte particles in the dispersion easily enter between the oxide solid electrolyte particles 11a, and thus are preferable. In addition, as described above, after the oxide solid-state electrolyte particles 11a are dispersed in the binder made of the lithium ion conductive polymer material 11b, the binder is cured by molding into a sheet shape to form the sheet-like member, and in this case, the lithium ion conductive polymer material 11b is allowed to enter between the oxide solid-state electrolyte particles 11a before the application, and therefore, the lithium ion conductive polymer material applied by the application may not enter between the oxide solid-state electrolyte particles 11 a.

In the present embodiment, when the lithium ion conductive polymer material is coated on both surfaces of the sheet member composed of the oxide solid electrolyte particles 11a, the lithium ion conductive polymer material is coated on each of both surfaces of the sheet member to such an extent that the lithium ion conductive polymer material becomes a layer. As a result, the lithium ion conductive polymer material on one surface of the oxide solid electrolyte layer 11 is cured to form the positive electrode side solid electrolyte dispersion polymer layer 12 shown in fig. 5, and the lithium ion conductive polymer material on the other surface of the oxide solid electrolyte layer 11 is cured to form the negative electrode side solid electrolyte dispersion polymer layer 15 shown in fig. 5.

(Preparation of cathode active material layer and cathode collector)

In the preparation of the positive electrode active material layer and the positive electrode current collector, the positive electrode active material 13a and the conductive auxiliary agent as needed are dispersed in the lithium ion conductive polymer material 13b, and the mixture is applied to the positive electrode current collector layer 14 and dried. In this way, the positive electrode active material layer 13 is provided on the positive electrode current collector layer 14.

(Preparation of negative electrode active material layer, negative electrode collector)

In the preparation of the anode active material layer and the anode current collector, the anode active material 16a and the conductive auxiliary agent as needed are dispersed in the lithium ion conductive polymer material 16b, and coated on the anode current collector layer 17 and dried. In this way, the anode active material layer 16 is provided on the anode current collector layer 17.

< Configuration procedure P2 >)

Fig. 6 is a diagram showing the mode of the present step. As shown in fig. 6, after the preparation step P1, the laminate of the positive electrode active material layer 13 and the positive electrode current collector layer 14 is arranged on one surface side of the oxide solid electrolyte layer 11 so that the positive electrode active material layer 13 faces the oxide solid electrolyte layer 11 side. However, as described above, the positive electrode side solid electrolyte dispersion polymer layer 12 is located on one surface of the oxide solid electrolyte layer 11, and thus the positive electrode active material layer 13 is disposed on the positive electrode side solid electrolyte dispersion polymer layer 12.

Further, on the other surface side of the oxide solid electrolyte layer 11, a laminate of the anode active material layer 16 and the anode current collector layer 17 is arranged so that the anode active material layer 16 faces the oxide solid electrolyte layer 11 side. However, as described above, since the negative electrode side solid electrolyte dispersion polymer layer 15 is located on the other surface of the oxide solid electrolyte layer 11, the negative electrode active material layer 16 is disposed on the negative electrode side solid electrolyte dispersion polymer layer 15.

As a result, as shown in fig. 6, a battery body 1b is obtained in which the oxide solid electrolyte layer 11, the positive electrode side solid electrolyte dispersion polymer layer 12, the positive electrode active material layer 13, the positive electrode current collector layer 14, the negative electrode side solid electrolyte dispersion polymer layer 15, the negative electrode active material layer 16, and the negative electrode current collector layer 17 are laminated.

< Integrated Process P3 >)

After the disposing step P2, the stacked oxide solid electrolyte layer 11, cathode-side solid electrolyte dispersion polymer layer 12, cathode active material layer 13, cathode current collector layer 14, anode-side solid electrolyte dispersion polymer layer 15, anode active material layer 16, and anode current collector layer 17 are integrated. The oxide solid electrolyte layer 11, the positive-electrode-side solid electrolyte dispersion polymer layer 12, and the negative-electrode-side solid electrolyte dispersion polymer layer 15 have been integrated, the positive electrode active material layer 13 and the positive electrode current collector layer 14 have been integrated, and the negative electrode active material layer 16 and the negative electrode current collector layer 17 have been integrated. Therefore, in this step, the positive electrode side solid electrolyte dispersion polymer layer 12 and the positive electrode active material layer 13 are integrated, and the negative electrode side solid electrolyte dispersion polymer layer 15 and the negative electrode active material layer 16 are integrated.

Fig. 7 is a diagram showing this step. As shown in fig. 7, in the present embodiment, the integration is performed by thermocompression bonding. Specifically, the battery body 1b is sandwiched between the pair of heated thermocompression bonding dies 21, 22. Then, the respective thermocompression bonding dies 21, 22 are pressure bonded in a heated state. At this time, the temperature of the thermocompression bonding dies 21, 22 is preferably a temperature higher than the temperature at which the lithium ion conductive polymer material constituting the positive electrode side solid electrolyte dispersion polymer layer 12 and the negative electrode side solid electrolyte dispersion polymer layer 15 softens. For example, if the lithium ion conductive polymer material is PEO, the softening temperature is approximately 100 ℃, and therefore, the temperature of the thermocompression bonding dies 21, 22 is preferably higher than this temperature. In addition, for example, as described above, in the case where the lithium ion conductive polymer material is PEO, the temperature is preferably 130 ℃ or lower in view of suppressing the outflow of the lithium ion conductive polymer material due to the increased fluidity. In addition, for example, as described above, in the case where the lithium ion conductive polymer material is PEO, it is more preferable that the temperature of the thermocompression bonding dies 21, 22 is between 110 ℃ and 120 ℃. In addition, from the viewpoint of firmly integrating the respective layers and suppressing the outflow of the lithium ion conductive polymer material, the pressure for pressing the battery body 1b is preferably, for example, 1MPa to 50 MPa.

In this step, a part of the lithium ion conductive polymer material constituting the positive electrode side solid electrolyte dispersion polymer layer 12 may enter the positive electrode active material layer 13, and a part of the lithium ion conductive polymer material constituting the negative electrode side solid electrolyte dispersion polymer layer 15 may enter the negative electrode active material layer 16.

In this way, the positive electrode side solid electrolyte dispersion polymer layer 12 and the positive electrode active material layer 13 are integrated, and the negative electrode side solid electrolyte dispersion polymer layer 15 and the negative electrode active material layer 16 are integrated, thereby obtaining the battery body 1b in the pack 10 shown in fig. 1.

< Sealing Process P4 >)

Next, the integrated battery body 1b is placed in the package material 10, and the package material 10 is sealed. The sealing is preferably performed by thermal fusion or the like.

Thus, the all-solid lithium secondary battery 1 shown in fig. 1 was obtained.

As described above, according to the method of manufacturing the all-solid lithium secondary battery 1 of the present embodiment, the positive electrode active material layer 13, the negative electrode active material layer 16, and the oxide solid electrolyte layer 11 are integrally formed. Therefore, using an oxide solid electrolyte that is easy to handle, the resistance between the positive electrode active material layer 13 and the oxide solid electrolyte layer 11 and between the negative electrode active material layer 16 and the oxide solid electrolyte layer 11 is reduced, and an all-solid-state lithium secondary battery 1 that can realize large current can be manufactured.

In the present embodiment, the integration step P3 is performed by thermocompression bonding. Therefore, for example, the integration process P3 can be performed more easily than in the case where the integration process P3 is performed using ultrasonic waves.

The present invention has been described above by way of example of embodiments, but the present invention is not limited thereto.

For example, in the above embodiment, the oxide solid electrolyte layer 11 has a structure in which the lithium ion conductive polymer material 11b enters at least a part between particles of the oxide solid electrolyte particles 11 a. However, in the present invention, the oxide solid electrolyte layer 11 may not have the lithium ion conductive polymer material 11b as long as the oxide solid electrolyte layer 11 has lithium ion conductivity. However, from the viewpoint of the oxide solid-state electrolyte layer 11 maintaining good lithium ion conductivity, it is preferable that the lithium ion conductive polymer material 11b enters at least a part between particles of the oxide solid-state electrolyte particles 11 a.

The lithium ion conductive polymer material 12b constituting the positive electrode side solid electrolyte dispersion polymer layer 12, the lithium ion conductive polymer material 15b constituting the negative electrode side solid electrolyte dispersion polymer layer 15, and the lithium ion conductive polymer material 11b between the particles that enter the oxide solid electrolyte particles 11a may be different materials. In this case, in the preparation step P1, the lithium ion conductive polymer material 11b between the particles entering the oxide solid electrolyte particles 11a is coated so that the lithium ion conductive polymer material 11b does not form a layer on the sheet member of the oxide solid electrolyte particles 11a, thereby obtaining the oxide solid electrolyte layer 11. Then, a lithium ion conductive polymer material to be the positive electrode side solid electrolyte dispersion polymer layer 12 or the negative electrode side solid electrolyte dispersion polymer layer 15 may be applied to the obtained oxide solid electrolyte layer 11.

The lithium ion conductive polymer material 13b may not enter between the positive electrode active materials 13a of the positive electrode active material layer 13, and the lithium ion conductive polymer material 16b may not enter between the negative electrode active materials 16a of the negative electrode active material layer 16.

In the above embodiment, the integration step P3 is performed by thermocompression bonding, but the integration step P3 may be performed by a method other than thermocompression bonding, such as ultrasonic welding.

Next, the polymer arranged between the particles of the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11 is a polymer having lithium ion conductivity, and the amount of lithium salt in the case where the lithium salt is dispersed in the polymer was studied.

Example 1

To produce the battery body 1b, a laminate body in which solid electrolyte dispersion polymer layers are provided on both surfaces of the oxide solid electrolyte layer 11 is prepared. In this preparation, first, a porous oxide solid electrolyte particle bonding layer to which the oxide solid electrolyte particles 11a are bonded is prepared. The oxide solid electrolyte particles are composed of LLZO.

Next, a coating liquid composed of a lithium ion conductive polymer material in which oxide solid electrolyte particles and a lithium salt are dispersed is coated on both sides of the oxide solid electrolyte particle bonding layer. PEO was used as a lithium ion conductive polymer material, liFSI was used as a lithium salt, and particles composed of LLZO were used as oxide solid electrolyte particles. In addition, the weight ratio of PEO to LiFSI was set to 1:1. by this coating, at least the lithium ion conductive polymer material and the lithium salt are made to enter between the oxide solid electrolyte particles in the oxide solid electrolyte particle bonding layer, the oxide solid electrolyte layer 11 shown in fig. 2 and 3 is produced, the positive electrode side solid electrolyte dispersion polymer layer 12 is produced from the layer composed of the coating liquid formed on one surface of the oxide solid electrolyte layer 11, and the negative electrode side solid electrolyte dispersion polymer layer 15 is produced from the layer composed of the coating liquid formed on the other surface of the oxide solid electrolyte layer 11.

A laminate in which the positive electrode active material layer 13 was provided on one surface of the positive electrode current collector layer 14 was prepared. Specifically, as the positive electrode current collector layer 14, aluminum foil is used, and a solution in which lithium Nickelate (NCA), carbon black, acrylic ester, and carboxymethyl cellulose (CMC) are dispersed is applied to one surface of the positive electrode current collector layer 14, and the positive electrode active material layer 13 is obtained by drying, as the laminate.

A laminate in which the anode active material layer 16 was provided on one surface of the anode current collector layer 17 was prepared. Specifically, a copper foil is used as the negative electrode current collector layer 17, and a solution in which graphitizable carbon, styrene butadiene block copolymer (SBR), and CMC are dispersed is applied to one surface of the negative electrode current collector layer 17, and the negative electrode active material layer 16 is obtained by drying, as the laminate.

Next, the 3 laminated bodies are stacked and integrated. Specifically, the positive electrode side solid electrolyte dispersion polymer layer 12 provided on one surface of the oxide solid electrolyte layer 11 and the positive electrode active material layer 13 provided on one surface of the positive electrode current collector layer 14 are superimposed, and the negative electrode side solid electrolyte dispersion polymer layer 15 provided on the other surface of the oxide solid electrolyte layer 11 and the negative electrode active material layer 16 provided on one surface of the negative electrode current collector layer 17 are superimposed. Next, the stacked laminate is integrally formed by thermocompression bonding.

Thus, the battery body 1b is obtained.

Next, an ac voltage is applied to the positive electrode collector layer 14 and the negative electrode collector layer 17 of the battery body 1b while sweeping the frequency, and impedance measurement is performed. A cole plot of this result is shown in fig. 8.

In fig. 8, the horizontal axis represents the resistance component, and the vertical axis represents the reactance component. As a result, the resistance of the battery body of example 1 was about 50Ω.

Example 2

Except that the weight ratio of PEO to LiFSI was 4: except for 1, a battery body 1b was produced in the same manner as in example 1. In general all-solid-state lithium secondary batteries other than the present invention, the weight ratio of PEO to LiFSI was the same as that of the present example. The impedance measurement was performed on the battery body 1b in the same manner as in example 1. A cole plot of this result is shown in fig. 8. As a result, the resistance of the battery body of the reference example was approximately 2000 Ω.

Even the resistance of example 2 is a very practical low resistance, but the result of the resistance of example 1 is approximately 1 to 40 times the resistance of example 2. Therefore, the lithium ion conductive polymer material 11b, the positive electrode side solid electrolyte dispersion polymer layer 12, and the lithium ion conductive polymer material 13b which enter between the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11 are PEO, and it is found that when LiFSI is dispersed in the lithium ion polymer material, it is preferable that LiFSI is 1 time or more by weight relative to PEO.

In addition, if the weight of LiFSI relative to PEO is greater than 2 times, there is a concern about strength, so that it is preferable that the weight of LiFSI relative to PEO is 2 times or less.

As described above, according to the present invention, an all-solid-state lithium secondary battery which can be handled easily and can realize a large current, and a method for manufacturing an all-solid-state lithium secondary battery can be provided, and can be expected to be used in the fields of batteries for automobiles, batteries for industrial equipment, batteries for consumer equipment, and the like.

Claims

1. An all-solid-state lithium secondary battery characterized by comprising:

An oxide solid electrolyte layer having an oxide solid electrolyte particle bonding layer bonded with oxide solid electrolyte particles having lithium ion conductivity,

A positive electrode active material layer disposed on one surface side of the oxide solid electrolyte layer,

A negative electrode active material layer disposed on the other surface side of the oxide solid electrolyte layer, and

A solid electrolyte dispersion polymer layer disposed between the positive electrode active material layer and the negative electrode active material layer and the oxide solid electrolyte layer, and configured such that a coating liquid made of a lithium ion conductive polymer material in which the oxide solid electrolyte particles and lithium salts are dispersed is coated on both surfaces of the oxide solid electrolyte particle bonding layer;

The positive electrode active material layer, the negative electrode active material layer, the solid electrolyte dispersion polymer layer, and the oxide solid electrolyte layer are integrally formed,

The oxide solid electrolyte layer is also provided with a lithium ion conductive polymer material which enters between the oxide solid electrolyte particles from the coating liquid,

The lithium ion conductive polymer material between the oxide solid electrolyte particles entering the oxide solid electrolyte layer and the lithium ion conductive polymer material of the solid electrolyte dispersion polymer layer are the same material,

The solid electrolyte dispersion polymer layer is disposed between the positive electrode active material layer and the oxide solid electrolyte layer and between the negative electrode active material layer and the oxide solid electrolyte layer,

The lithium salt is dispersed in the lithium ion conductive polymer material of the oxide solid electrolyte layer and the lithium ion conductive polymer material of the solid electrolyte dispersion polymer layer,

The lithium ion conductive polymer material of the oxide solid electrolyte layer and the lithium ion conductive polymer material of the solid electrolyte dispersion polymer layer are polyethylene oxide,

The lithium salt is lithium bis (fluorosulfonyl) imide,

In the coating liquid, the weight of the lithium salt is 1 to 2 times the weight of the lithium ion conductive polymer material.

2. The all-solid lithium secondary battery according to claim 1, wherein,

The lithium ion conductive polymer material of the solid electrolyte dispersion polymer layer enters at least a part between the oxide solid electrolyte particles of the oxide solid electrolyte layer.

3. A method for manufacturing an all-solid-state lithium secondary battery, comprising:

A disposing step of disposing the oxide solid electrolyte layer, the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte dispersion polymer layer in the following manner: the positive electrode active material layer is disposed on one surface side of an oxide solid electrolyte layer having lithium ion conductivity and having an oxide solid electrolyte particle bonding layer bonded with oxide solid electrolyte particles, the negative electrode active material layer is disposed on the other surface side of the oxide solid electrolyte layer, and the solid electrolyte dispersion polymer layer is disposed between the positive electrode active material layer and the negative electrode active material layer and the oxide solid electrolyte layer, the solid electrolyte dispersion polymer layer is formed by coating both surfaces of the oxide solid electrolyte particle bonding layer with a coating liquid composed of a lithium ion conductive polymer material in which the oxide solid electrolyte particles and lithium salts are dispersed, and

An integration step of integrating the positive electrode active material layer, the negative electrode active material layer, the solid electrolyte dispersion polymer layer, and the oxide solid electrolyte layer,

The lithium salt is lithium bis (fluorosulfonyl) imide,

4. The method for manufacturing an all-solid-state lithium secondary battery according to claim 3, wherein,

The integrating step is performed by thermocompression bonding.