CN114026727A

CN114026727A - All-solid-state lithium secondary battery and method for manufacturing all-solid-state lithium secondary battery

Info

Publication number: CN114026727A
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: 2022-02-08
Anticipated expiration: 2040-10-13
Also published as: CN114026727B; JPWO2021075420A1; JP7275300B2; WO2021075420A1

Abstract

An all-solid-state lithium secondary battery (1) is provided with: an oxide solid electrolyte layer (11) containing oxide solid electrolyte particles (11a) 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), the oxide solid electrolyte particles being 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 lithium secondary battery and a method for manufacturing the all-solid lithium secondary battery.

Background

Generally, lithium ion batteries using nonaqueous electrolytic solutions are widespread. However, since the electrolyte of the lithium ion battery is flammable and may cause a fire, or an organic solvent is used, the use temperature of the lithium ion battery is limited. Therefore, all solid-state lithium secondary batteries using polymer electrolytes are being developed. However, the polymer electrolyte has low ionic conductivity at low temperatures, and the range of use temperatures is narrower than that of a lithium ion battery using the above-described nonaqueous electrolytic solution. Therefore, all solid-state lithium secondary batteries using sulfide-based solid electrolytes are being developed. However, the reaction of sulfides with water may produce hydrogen sulfide, so the temperature range of use is limited. Therefore, it is desired to develop an all-solid-state battery using an oxide-based solid electrolyte that can compensate for such a disadvantage of the polymer electrolyte or the sulfide-based electrolyte.

For example, patent document 1 listed below describes an all-solid-state lithium secondary battery including: the composite solid electrolyte layer is formed by sandwiching a composite solid electrolyte layer having oxide particles having lithium ion conductivity and an amorphous portion having lithium ion conductivity 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 a surface of a solid electrolyte body for the purpose of reducing the resistance of an interface between the solid electrolyte body and an electrode.

Patent document 1: japanese patent laid-open publication 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 an oxide solid electrolyte as described in patent document 1 is difficult to produce hydrogen sulfide by reaction with water and easy to handle, but has a high internal resistance and a low conductivity as compared with an all solid-state lithium secondary battery using a sulfide electrolyte.

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

Therefore, in an all solid-state lithium secondary battery using an oxide solid electrolyte which is easy to handle, it is desired to reduce the internal resistance and increase the 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 problem, 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, the solid electrolyte dispersion polymer layer being 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-mentioned sulfide, the oxide does not generate a gas which requires attention for handling, such as hydrogen sulfide, even when it reacts with water. Therefore, the all solid-state lithium secondary battery of the present invention using the oxide solid electrolyte is easy to handle.

In the present specification, the state where the layers are formed integrally means a state where peeling is impossible and breakage occurs when peeling is to be forcibly performed. 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. In this way, the resistance between the integrated positive electrode active material layer, negative electrode active material layer, solid electrolyte dispersion polymer layer, and oxide solid electrolyte layer is lower than the resistance between the positive electrode active material layer, negative electrode active material layer, solid electrolyte dispersion polymer layer, and oxide solid electrolyte layer that are simply disposed adjacent to each other 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 oxide solid electrolyte particles have a higher lithium ion conductivity than a lithium ion conductive polymer material, the ion conductivity of the solid electrolyte dispersion polymer layer is higher than that of a layer made of only a 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 in a thickness larger than that of the adhesive layer of patent document 2 described above, which is formed only of a lithium ion conductive polymer material. Therefore, it is possible to suppress the increase in internal resistance due to the inability to fill the gap between the electrode and the solid electrolyte body, 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.

In addition, the method for manufacturing an all-solid-state lithium secondary battery according to the present invention includes: 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 such a manner that: the method for producing a lithium secondary battery includes the steps of positioning the positive electrode active material layer on one surface side of an oxide solid electrolyte layer containing oxide solid electrolyte particles and having lithium ion conductivity, positioning the negative electrode active material layer on the other surface side of the oxide solid electrolyte layer, and positioning the solid electrolyte dispersion polymer layer 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, and 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.

According to the method for manufacturing an all-solid-state lithium secondary battery, an oxide solid electrolyte which is easy to handle is used, the internal resistance is reduced, and an all-solid-state lithium secondary battery capable of realizing a large current can be manufactured.

As described above, according to the present invention, it is possible 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.

Drawings

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

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

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

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

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

Fig. 6 is a diagram showing an arrangement process.

Fig. 7 is a diagram showing an embodiment of the integration step.

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

Detailed Description

Preferred embodiments of an all solid-state lithium secondary battery and a method for manufacturing an all solid-state lithium secondary battery according to the present invention will be described below in detail with reference to the accompanying drawings. The following embodiments are provided to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention can be modified and improved without departing from the gist thereof. In addition, for the sake of easy understanding, a part of the drawings may be exaggeratedly illustrated.

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

< 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: the lithium ion conductive polymer material 11b is disposed in at least a part of the space between the particles of the oxide solid electrolyte particles 11a, that is, in at least a part of the space 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), Lithium Aluminum Germanium Phosphate (LAGP), and the like. Silicon (Si) and germanium (Ge) may be added to 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, for example, a 1090L laser diffraction particle diameter distribution measuring apparatus manufactured by CILAS corporation.

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 material having lithium ion conductivity as a polymer material can be mentioned. Examples of such a polymer material 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), thereby having lithium ion conductivity. As such a lithium salt, for example, lithium hexafluorophosphate (LiPF) can be cited₆) Lithium borofluoride (LiBF)₄) Lithium bis (oxalate) borate (LiBOB), lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium bis (fluorosulfonyl) imide (LiFSI). Further, a polymer having lithium ion conductivity such as PEO, PEG, PVDF, or the like 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 electrolyte particles in this case, the same particles as those of the oxide solid electrolyte that can be used for the oxide solid electrolyte particles 11a can be cited. In particular, lithium ion conductive oxides such as LATP and LLZO tend to have high ion conductivity of a lithium ion conductive polymer, and therefore, the lithium ion conductivity can be further increased by mixing.

As described above, since the oxide solid electrolyte layer 11 of the present embodiment is configured such that the lithium ion conductive polymer material 11b is interposed between the oxide solid electrolyte particles 11a, the resistance can be reduced as compared to a case where the oxide solid electrolyte layer 11 is configured only with the oxide solid electrolyte particles 11a and the lithium ion conductive polymer material 11b is not interposed between the oxide solid electrolyte particles 11 a. The oxide solid electrolyte layer 11 of such a 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 the lithium ion conductive polymer material 13b is interposed 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 a mixture thereof. The ternary system mentioned here is a system containing nickel, manganese, aluminum, or cobalt, for example.

The lithium ion conductive polymer material 13b inserted between the positive electrode active materials 13a can be the same material 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 interposed between the positive electrode active materials 13a and the lithium ion conductive polymer material 11b interposed between the particles of the oxide solid electrolyte particles 11a may be the same material or different materials.

Further, 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, 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 lithium ion conductive polymer material 12b, is interposed between positive electrode active material layer 13 and oxide solid electrolyte layer 11. As the lithium ion conductive polymer material 12b constituting the positive electrode-side solid electrolyte dispersion polymer layer 12, the same material as that of the lithium ion conductive polymer material 11b that can be used for the oxide solid electrolyte layer 11 can be cited.

As the oxide solid electrolyte of the oxide solid electrolyte particles 12a constituting the positive electrode-side solid electrolyte dispersion polymer layer 12, the same oxide solid electrolyte as that of the oxide solid electrolyte particles 11a that can be used in the oxide solid electrolyte layer 11 can be cited. In addition, from the viewpoint of reducing the contact resistance, it is preferable that the oxide solid electrolyte particles 12a of the positive electrode-side solid electrolyte-dispersed 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. Further, 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 formed of different oxide solid electrolytes. In this case, for example, LAGP or LLZO is used as the oxide solid electrolyte of the oxide solid electrolyte particles 11a constituting the oxide solid electrolyte layer 11, and LATP is used as the oxide solid electrolyte of the oxide solid electrolyte particles 12a constituting the positive electrode-side solid electrolyte dispersed polymer layer 12. With such a combination, the reduction resistance of the oxide solid electrolyte can be improved.

The particle diameter of oxide solid electrolyte particles 12a of positive electrode-side solid electrolyte dispersion polymer layer 12 may be the same as the particle diameter of oxide solid electrolyte particles 11a of 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 diameter of the oxide solid electrolyte particles 12a of the positive electrode-side solid electrolyte dispersion polymer layer 12 is smaller than the particle diameter 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 made thin, which is preferable because it contributes to a reduction in the resistance of the all-solid lithium secondary battery 1. As will be described later, when positive electrode-side solid electrolyte dispersion polymer layer 12 is formed by coating, oxide solid electrolyte particles 12a and lithium ion conductive polymer material 12b can be incorporated together between oxide solid electrolyte particles 11a of 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.

The average thickness of positive electrode-side solid electrolyte dispersion polymer layer 12 may be smaller than the particle diameter of oxide solid electrolyte particles 12 a. In this case, the positive electrode-side solid electrolyte dispersion polymer layer 12 becomes thicker at the portions where the oxide solid electrolyte particles 12a are present, and becomes thinner at the portions where the oxide solid electrolyte particles 12a are not present. Therefore, the oxide solid electrolyte particles 12a are likely to 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 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. This can reduce the resistance of positive electrode-side solid electrolyte dispersion polymer layer 12.

In the present embodiment, oxide solid electrolyte layer 11 and positive electrode-side solid electrolyte dispersion polymer layer 12 are formed integrally, and further, positive electrode active material layer 13 and positive electrode-side solid electrolyte dispersion polymer layer 12 are formed integrally, so that oxide solid electrolyte layer 11 and positive electrode active material layer 13 are formed integrally by positive electrode-side solid electrolyte dispersion polymer layer 12. Therefore, when oxide solid electrolyte layer 11 and 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 positive electrode-side solid electrolyte dispersion polymer layer 12 and oxide solid electrolyte layer 11, it is preferable that lithium ion conductive polymer material 15b constituting positive electrode-side solid electrolyte dispersion polymer layer 12 and lithium ion conductive polymer material 11b interposed between oxide solid electrolyte particles 11a be the same material. This is also preferable in that the positive electrode-side solid electrolyte dispersion polymer layer 12 and the lithium ion conductive polymer material 11b that has entered between the oxide solid electrolyte particles 11a can be simultaneously formed by coating. However, even if the lithium ion conductive polymer material 12b of the positive electrode-side solid electrolyte dispersion polymer layer 12 and the lithium ion conductive polymer material 11b inserted between the oxide solid electrolyte particles 11a are the same material, the positive electrode-side solid electrolyte dispersion polymer layer 12 may be provided on the surface of the oxide solid electrolyte layer 11 on the positive electrode side in a state where the lithium ion conductive polymer material 11b is inserted between the oxide solid electrolyte particles 11 a. The lithium ion conductive polymer material constituting positive electrode-side solid electrolyte dispersion polymer layer 12 and lithium ion conductive polymer material 11b inserted between oxide solid electrolyte particles 11a may be different materials from each other. In this case, for example, it is preferable to use PVDF as the lithium ion conductive polymer material constituting the positive electrode-side solid electrolyte dispersion polymer layer 12, and PEO as the lithium ion conductive polymer material 11b interposed between the oxide solid electrolyte particles 11 a. In such a combination, the battery voltage can be increased by using PVDF, which is less likely to decompose than PEO, on the high potential side. Therefore, it is possible to contribute to the increase in potential and the increase in energy of the all solid-state lithium secondary battery 1.

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. 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 different materials from each other. In this case, for example, it is preferable to use PEO as the lithium ion conductive polymer material 12b constituting the positive electrode side solid electrolyte dispersion polymer layer 12 and PVDF as the lithium ion conductive polymer material 13b interposed between the positive electrode active materials 13 a. In such a combination, the battery voltage can be increased by using PVDF, which is less likely to decompose than PEO, on the high potential side. Therefore, it is possible to contribute to the increase in potential and the increase in energy of the all solid-state lithium secondary battery 1.

< Positive electrode collector layer >

Positive electrode collector layer 14 is disposed on the surface of positive electrode active material layer 13 opposite to oxide solid electrolyte layer 11, and is formed integrally with positive electrode active material layer 13. The positive electrode collector layer 14 is made of a conductive and non-ionic 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 is interposed 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 graphitizable carbon, LTO, LMO, Si, Li, and a mixture thereof.

Examples of the lithium ion conductive polymer material 16b that is inserted between the negative electrode active materials 16a include materials that can be used for the lithium ion conductive polymer material 11 b. In the present embodiment, the lithium ion conductive polymer material 16b interposed between the negative electrode active materials 16a and the lithium ion conductive polymer material 11b interposed between the particles of the oxide solid electrolyte particles 11a may be the same material or 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 aid such as acetylene black may be dispersed in the lithium ion conductive polymer material 16b of the negative electrode active material layer 16.

< solid electrolyte dispersed polymer layer on negative electrode side >

In the present embodiment, the negative electrode-side solid electrolyte dispersion polymer layer 15 is interposed 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 a solid electrolyte dispersion polymer layer in which oxide solid electrolyte particles 15a are dispersed in a lithium ion conductive polymer material 15 b. Examples of the lithium ion conductive polymer material 15b constituting the negative electrode side solid electrolyte dispersion polymer layer 15 include materials that can be used for the lithium ion conductive polymer material 11 b.

As the oxide solid electrolyte of the oxide solid electrolyte particles 15a constituting the negative electrode-side solid electrolyte dispersion polymer layer 15, the same oxide solid electrolyte as that of the oxide solid electrolyte particles 11a that can be used in the oxide solid electrolyte layer 11 can be cited. In addition, from the viewpoint of reducing the 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. Further, 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 formed of different oxide solid electrolytes. In this case, for example, LATP is used in the oxide solid electrolyte of the oxide solid electrolyte particles 11a constituting the oxide solid electrolyte layer 11, and lag and LLZO are used in the oxide solid electrolyte of the oxide solid electrolyte particles 15a constituting the negative electrode-side solid electrolyte dispersion polymer layer 15. By combining these, the reduction resistance in 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 diameter of the oxide solid electrolyte particles 15a of the negative electrode side solid electrolyte dispersion polymer layer 15 is smaller than the particle diameter 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 thin, which is preferable because it contributes to the reduction in resistance of the all solid lithium secondary battery 1. In addition, when the negative electrode side solid electrolyte dispersion polymer layer 15 is formed by coating as described later, the oxide solid electrolyte particles 15a and the lithium ion conductive polymer material 15b can be incorporated together between 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 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 portions where the oxide solid electrolyte particles 15a are present, and becomes thinner at the portions where the oxide solid electrolyte particles 15a are not present. Therefore, the oxide solid electrolyte particles 15a 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 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. This makes it possible to reduce the resistance of the negative electrode-side solid electrolyte dispersion polymer layer 15.

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 that 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, destruction may occur.

In addition, from the viewpoint of being able to improve the strength of integration of the negative electrode-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 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 be the same material. This is also preferable in that the negative electrode side solid electrolyte dispersion polymer layer 15 and the lithium ion conductive polymer material 11b that has entered between the oxide solid electrolyte particles 11a can be simultaneously formed by coating. However, even if 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 are the same material, the negative electrode side solid electrolyte dispersion polymer layer 15 may be provided on the surface of the oxide solid electrolyte layer 11 on the negative electrode side in a state where the lithium ion conductive polymer material 11b is interposed between the oxide solid electrolyte particles 11 a. 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 inserted between the oxide solid electrolyte particles 11a may be different materials from each other. In this case, for example, PVDF, SBR, acrylate, 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 suitably used as the lithium ion conductive polymer material 11b to be incorporated 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. 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, it is preferable to use PVDF as the lithium ion conductive polymer material constituting the negative electrode side solid electrolyte dispersion polymer layer 15, and use a mixture of PEO and PVDF as the lithium ion conductive polymer material 13b that enters between the negative electrode active materials 16 a. With 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 collector layer >

The negative electrode collector layer 17 is disposed on the 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 collector layer 17, for example, the same material as that of the positive electrode collector layer 14 can be cited.

< packaging Material >

The packaging material 10 is a member that houses and seals the positive electrode 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 collector layer 17. Further, a part of the positive electrode collector layer 14 and the negative electrode collector layer 17 is led out to the outside of the packaging material 10 as an electrode.

The structure of the packing material 10 is not particularly limited as long as it can prevent external oxygen, moisture, and the like from entering the region surrounded by the packing material 10 and does not conduct electricity to 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 an oxide solid electrolyte, and unlike sulfides, oxides do not generate gases requiring attention such as hydrogen sulfide even when they react with water, and thus handling is easy. In 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, 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. The resistance between the layers thus integrated is lower than the resistance between the layers that are simply disposed adjacent to each other without being integrated.

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

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 of the present embodiment will be described.

Fig. 4 is a flowchart of a method for manufacturing the all solid-state 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, a placement step P2, an integration step P3, and a sealing step P4.

< preparation Process P1 >

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

(preparation of oxide solid electrolyte layer)

In preparation of the oxide solid electrolyte layer 11, first, a green sheet (green sheet) in which oxide solid electrolyte particles 11a are dispersed in a binder is prepared, and then, firing is performed to obtain a porous sheet-like member which becomes the oxide solid electrolyte layer 11 in which the oxide solid electrolyte particles 11a are integrated with each other. Alternatively, the oxide solid electrolyte particles 11a may be placed in a mold, and fired under a predetermined pressure in a sheet-like state to obtain a porous sheet-like member serving as the oxide solid electrolyte layer 11. Still alternatively, the oxide solid electrolyte particles 11a may be dispersed in a binder, and then formed into a sheet shape and the binder may be cured. The binder may be made of the lithium ion conductive polymer material 11 b. Alternatively, the binder may not be constituted by the lithium ion conductive polymer material 11b, but in this embodiment, the lithium ion conductive polymer material 11b is configured to be inserted between the oxide solid electrolyte particles 11a, and therefore, in this case, the amount of the binder is such that voids can be formed between the oxide solid electrolyte particles 11 a. Thus, a sheet-like member containing the oxide solid electrolyte particles 11a was obtained.

Next, a dispersion liquid in which oxide solid electrolyte particles are dispersed in a lithium ion conductive polymer material is applied to both surfaces of the sheet-like 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. In this way, the oxide solid electrolyte layer 11 in which the lithium ion conductive polymer material 11b enters between the oxide solid electrolyte particles 11a shown in fig. 5 is obtained. In this case, it is more preferable that the oxide solid electrolyte particles in the dispersion enter between the oxide solid electrolyte particles 11a from the viewpoint of lowering the resistance. In this case, it is preferable that the oxide solid electrolyte particles in the dispersion liquid easily enter between the oxide solid electrolyte particles 11a as long as the particle diameter of the oxide solid electrolyte particles in the dispersion liquid is smaller than the particle diameter of the oxide solid electrolyte particles 11a of the sheet-like member. In addition, as described above, in the case where the above-described sheet-like member is obtained by dispersing the oxide solid electrolyte particles 11a in the binder made of the lithium ion conductive polymer material 11b and then forming the sheet-like member into a shape of a sheet and curing the binder, the lithium ion conductive polymer material 11b is interposed between the oxide solid electrolyte particles 11a before the above-described coating, and therefore, the lithium ion conductive polymer material applied by the coating may not be interposed between the oxide solid electrolyte particles 11 a.

In the present embodiment, when the lithium ion conductive polymer material is applied to both surfaces of the sheet-like member made of the oxide solid electrolyte particles 11a, the lithium ion conductive polymer material is applied to each of both surfaces of the sheet-like 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 solidified to become 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 solidified to become the negative electrode-side solid electrolyte dispersion polymer layer 15 shown in fig. 5.

(preparation of Positive electrode active Material layer and Positive electrode collector)

In preparation of the positive electrode active material layer and the positive electrode current collector, the positive electrode active material 13a and, if necessary, a conductive auxiliary are dispersed in the lithium ion conductive polymer material 13b, and the resultant 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 collector layer 14.

(preparation of negative electrode active material layer and negative electrode collector)

In preparation of the negative electrode active material layer and the negative electrode current collector, the negative electrode active material 16a and, if necessary, the conductive assistant are dispersed in the lithium ion conductive polymer material 16b, and the resultant is applied to the negative electrode current collector layer 17 and dried. In this way, the negative electrode active material layer 16 is provided on the negative electrode current collector layer 17.

< Placement Process P2 >

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

On the other surface side of the oxide solid electrolyte layer 11, a laminate of the negative electrode active material layer 16 and the negative electrode current collector layer 17 is disposed so that the negative electrode active material layer 16 faces the oxide solid electrolyte layer 11. 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 shown in fig. 6, a battery body 1b was obtained in which oxide solid electrolyte layer 11, positive electrode-side solid electrolyte dispersion polymer layer 12, positive electrode active material layer 13, positive electrode collector layer 14, negative electrode-side solid electrolyte dispersion polymer layer 15, negative electrode active material layer 16, and negative electrode collector layer 17 were laminated.

< integration Process P3 >

After the disposing step P2, the stacked oxide solid electrolyte layer 11, positive electrode-side solid electrolyte dispersion polymer layer 12, positive electrode active material layer 13, positive electrode collector layer 14, negative electrode-side solid electrolyte dispersion polymer layer 15, negative electrode active material layer 16, and negative electrode 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 collector layer 14 have been integrated, and the negative electrode active material layer 16 and the negative electrode 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, integration is performed by thermocompression bonding. Specifically, the battery body 1b is sandwiched between the pair of heated thermocompression bonding dies 21 and 22. Then, the respective thermocompression bonding dies 21 and 22 are subjected to pressure bonding in a heated state. At this time, the temperature of the thermocompression bonding dies 21 and 22 is preferably higher than the temperature at which the lithium ion conductive polymer material constituting the positive electrode-side solid electrolyte dispersed polymer layer 12 and the negative electrode-side solid electrolyte dispersed polymer layer 15 softens. For example, when the lithium ion conductive polymer material is PEO, the softening temperature is approximately 100 ℃, and therefore, the temperature of the thermocompression bonding dies 21 and 22 is preferably higher than this temperature. For example, as described above, in the case where the lithium ion conductive polymer material is PEO, the temperature is preferably 130 ℃ or lower from the viewpoint of suppressing the outflow of the lithium ion conductive polymer material due to the high fluidity. For example, as described above, when the lithium ion conductive polymer material is PEO, the temperature of the thermocompression bonding dies 21 and 22 is more preferably 110 ℃ to 120 ℃. In addition, the pressure for pressing the battery body 1b is preferably, for example, 1MPa to 50MPa, from the viewpoint of firmly integrating the layers and suppressing the outflow of the lithium ion conductive polymer material.

In this step, a part of the lithium ion conductive polymer material constituting the positive electrode-side solid electrolyte dispersion polymer layer 12 may be incorporated into 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 be incorporated into the negative electrode active material layer 16.

As a result, 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, whereby the battery cell 1b in the casing 10 shown in fig. 1 is obtained.

< sealing Process P4 >

Next, the integrated battery body 1b is placed in the packing 10, and the packing 10 is sealed. The sealing is preferably performed by heat welding or the like.

In this way, the all solid-state lithium secondary battery 1 shown in fig. 1 was obtained.

As described above, according to the method for manufacturing the all solid-state 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, 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 by using the oxide solid electrolyte which is easy to handle, and the all solid lithium secondary battery 1 capable of achieving a large current can be manufactured.

In the present embodiment, the integrating step P3 is performed by thermocompression bonding. Therefore, for example, the integrating step P3 can be performed more easily than the case of performing the integrating step P3 using ultrasonic waves.

The present invention has been described above by taking the embodiments as examples, but the present invention is not limited to these.

For example, in the above embodiment, in the oxide solid electrolyte layer 11, the lithium ion conductive polymer material 11b is inserted into at least a part of the oxide solid electrolyte particles 11a between the particles. However, in the present invention, the oxide solid state electrolyte layer 11 may not have the lithium ion conductive polymer material 11b as long as the oxide solid state electrolyte layer 11 has lithium ion conductivity. However, from the viewpoint that the oxide solid electrolyte layer 11 well maintains lithium ion conductivity, it is preferable that the lithium ion conductive polymer material 11b enters at least a part between the particles of the oxide solid 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 interposed between the particles of the oxide solid electrolyte particles 11a may be different materials. In this case, in the preparation step P1, when the lithium ion conductive polymer material 11b that has entered between the particles of the oxide solid electrolyte particles 11a is coated, the oxide solid electrolyte layer 11 is obtained by coating the lithium ion conductive polymer material 11b so that the layer is not formed on the sheet member of the oxide solid electrolyte particles 11 a. 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 coated on the obtained oxide solid electrolyte layer 11.

The lithium ion conductive polymer material 13b may not be interposed 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 be interposed between the negative electrode active materials 16a of the negative electrode active material layer 16.

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

Next, the polymer disposed 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 a lithium salt is dispersed in the polymer is investigated.

(example 1)

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

Next, a coating solution made of a lithium ion conductive polymer material in which oxide solid electrolyte particles and a lithium salt are dispersed is applied to both sides of the oxide solid electrolyte seed binding layer. PEO was used as the lithium ion conductive polymer material, LiFSI was used as the lithium salt, and particles composed of LLZO were used as the oxide solid electrolyte particles. In addition, the weight ratio of PEO to LiFSI was made to be 1: 1. by this coating, an oxide solid electrolyte layer 11 shown in fig. 2 and 3 is produced by incorporating at least a lithium ion conductive polymer material and a lithium salt between the oxide solid electrolyte particles in the oxide solid electrolyte particle sub-bonding layer, and a positive electrode side solid electrolyte dispersed polymer layer 12 is produced by a layer formed from a coating liquid formed on one surface of the oxide solid electrolyte layer 11, and a negative electrode side solid electrolyte dispersed polymer layer 15 is produced by a layer formed from a 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 is provided on one surface of the positive electrode current collector layer 14 is prepared. Specifically, an aluminum foil is used as the positive electrode collector layer 14, and a solution in which lithium Nickelate (NCA), carbon black, acrylic acid ester, and carboxymethyl cellulose (CMC) are dispersed is applied to one surface of the positive electrode collector layer 14, followed by drying to obtain the positive electrode active material layer 13 as the above-described laminate.

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

Next, the 3 laminated bodies were stacked and integrated. Specifically, positive electrode-side solid electrolyte dispersed polymer layer 12 provided on one surface of oxide solid electrolyte layer 11 and positive electrode active material layer 13 provided on one surface of positive electrode collector layer 14 are stacked, and negative electrode-side solid electrolyte dispersed polymer layer 15 provided on the other surface of oxide solid electrolyte layer 11 and negative electrode active material layer 16 provided on one surface of negative electrode collector layer 17 are stacked. Next, the stacked laminated bodies are integrated 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. The results are shown in the cole plot of fig. 8.

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

(example 2)

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

The resistance of example 2 is a low resistance that is sufficiently practical, but the resistance of example 1 is approximately 40 to 1 times the resistance of example 2. Therefore, the lithium ion polymer material of the lithium ion conductive polymer material 11b, the positive electrode side solid electrolyte dispersed polymer layer 12, and the lithium ion conductive polymer material 13b that has entered between the oxide solid electrolyte particles 11a of the oxide solid electrolyte layer 11 is PEO, and it is found that, in the case where LiFSI is dispersed in this lithium ion polymer material, the weight of LiFSI relative to PEO is preferably 1 time or more.

Further, when the weight of LiFSI to PEO is more than 2 times, there is a concern about strength, and therefore, it is preferable that the weight of LiFSI to PEO is 2 times or less.

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

Claims

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

an oxide solid electrolyte layer containing 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, an

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, the solid electrolyte dispersion polymer layer being 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.

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

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

the oxide solid electrolyte layer further has a lithium ion conductive polymer material interposed between the oxide solid electrolyte particles,

the lithium ion conductive polymer material that enters between the oxide solid electrolyte particles of the oxide solid electrolyte layer and the lithium ion conductive polymer material of the solid electrolyte dispersed polymer layer are the same material.

4. The all solid-state lithium secondary battery according to claim 3,

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,

lithium salts are 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, respectively,

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,

the weight of the lithium salt is 1 to 2 times the weight of the lithium ion conductive polymer material.

5. The all solid-state lithium secondary battery according to claim 1,

the lithium ion conductive polymer material that enters between the oxide solid electrolyte particles of the oxide solid electrolyte layer and the lithium ion conductive polymer material of the solid electrolyte dispersed polymer layer are different materials.

6. The all solid-state lithium secondary battery according to any one of claims 1 to 5,

the oxide solid electrolyte particles of the solid electrolyte dispersion polymer layer have a smaller particle diameter than the oxide solid electrolyte particles of the oxide solid electrolyte layer.

7. 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 such a manner that: positioning the positive electrode active material layer on one surface side of an oxide solid electrolyte layer containing oxide solid electrolyte particles and having lithium ion conductivity, positioning the negative electrode active material layer on the other surface side of the oxide solid electrolyte layer, positioning the solid electrolyte dispersion polymer layer 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 being formed by dispersing the oxide solid electrolyte particles in a lithium ion conductive polymer material having lithium ion conductivity, and

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.

8. The method for manufacturing an all-solid lithium secondary battery according to claim 7,

the integration step is performed by thermocompression bonding.