JP7454336B2 - An all-solid-state lithium-ion secondary battery and its manufacturing method, an all-solid-state lithium-ion secondary battery system using the same, and a charging method for an all-solid-state lithium-ion secondary battery - Google Patents

Description

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

In recent years, in order to combat global warming, it has been strongly desired to reduce the amount of carbon dioxide. In the automobile industry, expectations are high for reducing carbon dioxide emissions through the introduction of electric vehicles (EVs) and hybrid electric vehicles (HEVs), and non-aqueous batteries such as secondary batteries for motor drives hold the key to their practical application. Electrolyte secondary batteries are actively being developed.

Secondary batteries for motor drives are required to have extremely high output characteristics and high energy compared to consumer lithium ion secondary batteries used in mobile phones, notebook computers, and the like. Therefore, lithium ion secondary batteries, which have the highest theoretical energy of all practical batteries, are attracting attention and are currently being rapidly developed.

Here, lithium ion secondary batteries that are currently in widespread use use a flammable organic electrolyte as an electrolyte. Such liquid-based lithium ion secondary batteries require more stringent safety measures against leakage, short circuits, overcharging, etc. than other batteries.

Therefore, in recent years, research and development on all-solid-state batteries such as all-solid lithium ion secondary batteries using oxide-based or sulfide-based solid electrolytes as electrolytes has been actively conducted. A solid electrolyte is a material mainly composed of an ion conductor capable of ion conduction in a solid state. Therefore, in principle, all-solid-state lithium ion secondary batteries do not suffer from various problems caused by flammable organic electrolytes, unlike conventional liquid-based lithium ion secondary batteries. Furthermore, in general, the use of high-potential, large-capacity positive electrode materials and large-capacity negative electrode materials can significantly improve the output density and energy density of the battery. All-solid-state lithium-ion secondary batteries using elemental sulfur (S) or sulfide-based materials as positive electrode active materials are promising candidates.

By the way, in a lithium ion secondary battery, the negative electrode potential decreases as the charging progresses. When the negative electrode potential decreases below 0 V (vs. Li/Li ⁺ ), metallic lithium is precipitated at the negative electrode and dendrite crystals are deposited (this phenomenon is also referred to as metallic lithium electrodeposition). When metal lithium electrodeposition occurs, there is a problem in that the deposited dendrites penetrate the electrolyte layer, causing an internal short circuit in the battery.

For the purpose of preventing such electrodeposition of metallic lithium, for example, Patent Document 1 discloses that a solid electrolyte layer of an all-solid-state lithium ion secondary battery is formed by a vapor phase method, and pinholes in the solid electrolyte layer are formed. discloses a technique in which a liquid substance such as an ionic liquid is present which reacts with metallic lithium to inactivate the metallic lithium. According to Patent Document 1, with such a configuration, even if metallic lithium dendrites grow through pinholes in the solid electrolyte layer, they can be inactivated, and internal short circuits in the battery can be reliably prevented. It is said that

Japanese Patent Application Publication No. 2009-218005

Here, in the technique disclosed in Patent Document 1, a liquid substance such as an ionic liquid is used to inactivate dendrites of metallic lithium. For this reason, the battery configured in this manner has a problem in that the operating temperature range is limited and cannot be operated in a wide temperature range.

Therefore, an object of the present invention is to provide a means for preventing the growth of dendrites of metallic lithium while enabling operation in a wide temperature range in an all-solid-state lithium ion secondary battery.

According to one embodiment of the present invention, there is provided a positive electrode in which a positive electrode active material layer containing a positive electrode active material capable of intercalating and deintercalating lithium ions is disposed on the surface of a positive electrode current collector, and a negative electrode active material capable of intercalating and deintercalating lithium ions. a negative electrode in which a negative electrode active material layer containing a substance is disposed on the surface of a negative electrode current collector; and a solid electrolyte layer interposed between the positive electrode active material layer and the negative electrode active material layer and containing a solid electrolyte. An all-solid-state lithium ion secondary battery including a power generation element having the following is provided. The battery is characterized in that the solid electrolyte layer has an electrodeposition growth inhibiting layer containing a solid material having a higher electrode potential than metallic lithium.

According to another aspect of the present invention, a solid electrolyte material is powder-molded to produce a sheet-like first sub-solid electrolyte layer, and at least one of the first sub-solid electrolyte layers. A solid electrolyte material and a solid material having a higher electrode potential than metallic lithium are powder-molded on the exposed surface of the metal lithium to produce a sheet-like electrodeposition growth inhibiting layer, and the exposed surface of the electrodeposition growth inhibiting layer is Also provided is a method for manufacturing a solid electrolyte layer for an all-solid-state lithium ion secondary battery, which includes producing a sheet-like second sub-solid electrolyte layer by compacting a solid electrolyte material. Ru.

According to the present invention, in an all-solid lithium ion secondary battery, it is possible to prevent the growth of metallic lithium dendrites while enabling operation in a wide temperature range.

FIG. 1 is a perspective view showing the appearance of a flat stacked battery, which is an embodiment of an all-solid-state battery according to the present invention. FIG. 2 is a sectional view taken along line 2-2 shown in FIG. FIG. 3 is a cross-sectional view of a single cell layer that constitutes the power generation element of the stacked battery shown in FIGS. 1 and 2. FIG. 4 is a cross-sectional view showing a modified example of the laminated battery according to the embodiment shown in FIG. FIG. 5 is an explanatory diagram for explaining a method for manufacturing the solid electrolyte layer 17 according to the embodiment shown in FIG. FIG. 6 is an explanatory diagram for explaining a method of manufacturing the solid electrolyte layer 17 according to the embodiment shown in FIG. FIG. 7 is a block diagram for explaining the configuration of an all-solid-state lithium ion secondary battery system according to an embodiment of the present invention. FIG. 8 is a flowchart showing the procedure of charging processing in the secondary battery system. FIG. 9 is a subroutine flowchart of step S109 in FIG. FIG. 10 is an equivalent circuit diagram of a secondary battery. FIG. 11 is a subroutine flowchart of step S111 (electrodeposition detection control) in FIG.

《All-solid-state lithium ion secondary battery》
One form of the present invention includes a positive electrode in which a positive electrode active material layer containing a positive electrode active material capable of intercalating and deintercalating lithium ions is disposed on the surface of a positive electrode current collector, and a negative electrode active material capable of intercalating and deintercalating lithium ions. a negative electrode including a negative electrode active material layer disposed on the surface of a negative electrode current collector; and a solid electrolyte layer interposed between the positive electrode active material layer and the negative electrode active material layer and containing a solid electrolyte. The present invention is an all-solid-state lithium ion secondary battery including a power generation element, wherein the solid electrolyte layer has an electrodeposition growth inhibiting layer containing a solid material having a higher electrode potential than metallic lithium.

Hereinafter, the embodiments of the present embodiment described above will be described with reference to the drawings, but the technical scope of the present invention should be determined based on the claims, and is not limited to only the following embodiments. Note that the dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios.

FIG. 1 is a perspective view showing the appearance of a flat stacked battery, which is an embodiment of an all-solid-state battery according to the present invention. FIG. 2 is a sectional view taken along line 2-2 shown in FIG. By using a stacked structure, the battery can be made more compact and have a higher capacity. In this specification, a flat stacked non-bipolar lithium ion secondary battery (hereinafter also simply referred to as a "stacked battery") shown in FIGS. 1 and 2 will be described in detail as an example. However, when looking at the internal electrical connection form (electrode structure) of the all-solid-state battery according to this embodiment, both non-bipolar (internal parallel connection type) batteries and bipolar (internal series connection type) batteries It is applicable.

As shown in FIG. 1, the stacked battery 10 has a flat rectangular shape, and a positive current collector plate 25 and a negative current collector plate 27 for extracting power are pulled out from both sides of the battery. There is. The power generation element 21 is surrounded by the battery exterior material (laminate film 29) of the stacked battery 10, and its periphery is heat-sealed. It is sealed when pulled out.

Note that the all-solid-state battery according to this embodiment is not limited to a stacked flat battery. A wound type all-solid-state battery may have a cylindrical shape, or may be a cylindrical shape transformed into a rectangular flat shape, etc. There are no particular restrictions. The above-mentioned cylindrical shape is not particularly limited, and a laminate film or a conventional cylindrical can (metal can) may be used for the exterior material. Preferably, the power generation element is housed inside a laminate film containing aluminum. With this form, weight reduction can be achieved.

Moreover, there is no particular restriction on the removal of the current collector plates (25, 27) shown in FIG. The positive electrode current collector plate 25 and the negative electrode current collector plate 27 may be drawn out from the same side, or the positive electrode current collector plate 25 and the negative electrode current collector plate 27 may be divided into a plurality of parts and taken out from each side. However, the present invention is not limited to what is shown in FIG. Further, in a wound type lithium ion battery, the terminals may be formed using, for example, a cylindrical can (metal can) instead of a tab.

As shown in FIG. 2, the stacked battery 10 of this embodiment has a structure in which a flat, substantially rectangular power generation element 21 in which charge and discharge reactions actually proceed is sealed inside a laminate film 29 that is a battery exterior material. has. Here, the power generation element 21 has a structure in which a positive electrode, a solid electrolyte layer 17, and a negative electrode are laminated. The positive electrode has a structure in which positive electrode active material layers 13 containing a positive electrode active material are disposed on both sides of a positive electrode current collector 11. The negative electrode has a structure in which negative electrode active material layers 15 containing a negative electrode active material are disposed on both sides of a negative electrode current collector 12. Specifically, one positive electrode active material layer 13 and the adjacent negative electrode active material layer 15 face each other with the solid electrolyte layer 17 in between, and the positive electrode, the solid electrolyte layer, and the negative electrode are stacked in this order. ing. Thereby, the adjacent positive electrode, solid electrolyte layer, and negative electrode constitute one single cell layer 19. Therefore, it can be said that the stacked battery 10 shown in FIG. 1 has a configuration in which a plurality of cell layers 19 are stacked and electrically connected in parallel.

As shown in FIG. 2, the positive electrode active material layer 13 is disposed on only one side of the outermost positive electrode current collectors located on both outermost layers of the power generation element 21, but active material layers are provided on both surfaces. It's okay to be hit. That is, instead of using a current collector exclusively for the outermost layer with an active material layer provided on only one side, a current collector with active material layers on both sides may be used as it is as the outermost layer current collector.

The positive electrode current collector 11 and the negative electrode current collector 12 are each attached with a positive electrode current collector plate (tab) 25 and a negative electrode current collector plate (tab) 27 that are electrically connected to each electrode (positive electrode and negative electrode), and are made of battery exterior material. It has a structure in which it is sandwiched between the ends of a certain laminate film 29 and led out to the outside of the laminate film 29 . The positive electrode current collector plate 25 and the negative electrode current collector plate 27 are ultrasonically welded to the positive electrode current collector 11 and the negative electrode current collector 13 of each electrode via a positive electrode lead and a negative electrode lead (not shown), respectively, as necessary. It may be attached by resistance welding or the like.

FIG. 3 is a cross-sectional view of the unit cell layer 19 that constitutes the power generation element 21 of the stacked battery 10 shown in FIGS. 1 and 2. FIG. In FIG. 3, the positive electrode current collector 11, the positive electrode active material layer 13, the solid electrolyte layer 17, the negative electrode active material layer 15, and the negative electrode current collector 12 constituting the unit cell layer 19 are laminated in this order. ing. Further, the solid electrolyte layer 17 includes a first sub-solid electrolyte layer 17a made of a solid electrolyte material, an electrodeposition growth suppression layer 17b made of vapor grown carbon fiber (VGCF) and a solid electrolyte material, and a solid electrolyte material. and the second sub-solid electrolyte layer 17c are laminated in this order.

In the embodiment shown in FIG. 3, for example, when charging the stacked battery 10, dendrites made of metallic lithium may be generated in the negative electrode active material layer 15 by electrodeposition. This dendrite grows toward the positive electrode active material layer 13 side, but when it comes into contact with the vapor grown carbon fiber (VGCF) constituting the electrodeposition growth inhibiting layer, further growth is inhibited. This is because the electrode potential of the vapor grown carbon fiber (VGCF) is higher than that of the metallic lithium that makes up the dendrite, so the metallic lithium that comes into contact with the vapor grown carbon fiber (VGCF) is oxidized and turns into lithium ions. This is because it is converted to That is, in the embodiment shown in FIG. 3, vapor grown carbon fiber (VGCF), which is a solid material with a higher electrode potential than metal lithium, exhibits the function of suppressing the growth of dendrites. Since the all-solid-state lithium ion secondary battery according to this embodiment does not use a liquid component unlike the technology described in Patent Document 1, it is possible to operate in a wide temperature range while allowing the growth of metallic lithium dendrites. It has the advantage of being able to prevent

The main constituent members of the all-solid-state battery according to this embodiment will be explained below.

[Current collector]
The current collector has a function of mediating the movement of electrons from one surface in contact with the positive electrode active material layer to the other surface in contact with the negative electrode active material layer. There is no particular restriction on the material constituting the current collector. As the constituent material of the current collector, for example, metal or conductive resin may be used.

Specifically, examples of the metal include aluminum, nickel, iron, stainless steel, titanium, and copper. In addition to these, a cladding material of nickel and aluminum, a cladding material of copper and aluminum, etc. may be used. Alternatively, it may be a foil whose metal surface is coated with aluminum. Among these, aluminum, stainless steel, copper, and nickel are preferred from the viewpoints of electron conductivity, battery operating potential, adhesion of the negative electrode active material to the current collector by sputtering, and the like.

Furthermore, examples of the latter resin having electrical conductivity include resins in which a conductive filler is added to a non-conductive polymer material as necessary.

Examples of non-conductive polymer materials include polyethylene (PE; high-density polyethylene (HDPE), low-density polyethylene (LDPE), etc.), polypropylene (PP), polyethylene terephthalate (PET), polyethernitrile (PEN), polyimide. (PI), polyamideimide (PAI), polyamide (PA), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA) , polyvinyl chloride (PVC), polyvinylidene fluoride (PVdF), or polystyrene (PS). Such non-conductive polymeric materials can have excellent potential or solvent resistance.

A conductive filler may be added to the above-mentioned conductive polymer material or non-conductive polymer material as necessary. In particular, when the resin serving as the base material of the current collector consists only of non-conductive polymers, a conductive filler is inevitably required to impart conductivity to the resin.

The conductive filler can be used without particular limitation as long as it is a substance that has conductivity. For example, metals, conductive carbon, and the like are examples of materials with excellent conductivity, potential resistance, or lithium ion blocking properties. The metal is not particularly limited, but includes at least one metal selected from the group consisting of Ni, Ti, Al, Cu, Pt, Fe, Cr, Sn, Zn, In, and Sb, or containing these metals. Preferably, it contains an alloy or a metal oxide. Furthermore, there are no particular limitations on the conductive carbon. Preferably, it is selected from the group consisting of acetylene black, Vulcan (registered trademark), Black Pearl (registered trademark), carbon nanofiber, Ketjenblack (registered trademark), carbon nanotube, carbon nanohorn, carbon nanoballoon, and fullerene. It contains at least one kind.

The amount of conductive filler added is not particularly limited as long as it can impart sufficient conductivity to the current collector, and is generally 5 to 80% by mass based on 100% by mass of the total mass of the current collector. It is.

Note that the current collector may have a single-layer structure made of a single material, or may have a laminated structure in which layers made of these materials are appropriately combined. From the viewpoint of reducing the weight of the current collector, it is preferable to include at least a conductive resin layer made of a resin having conductivity. Further, from the viewpoint of blocking the movement of lithium ions between the cell layers, a metal layer may be provided on a part of the current collector.

[Negative electrode active material layer]
The negative electrode active material layer contains a negative electrode active material. The type of negative electrode active material is not particularly limited, but includes carbon materials, metal oxides, and metal active materials. Examples of carbon materials include natural graphite, artificial graphite, mesocarbon microbeads (MCMB), highly oriented graphite (HOPG), hard carbon, and soft carbon. Furthermore, examples of metal oxides include Nb ₂ O ₅ and Li ₄ Ti ₅ O ₁₂ . Furthermore, a silicon-based negative electrode active material or a tin-based negative electrode active material may be used. Here, silicon and tin belong to Group 14 elements, and are known to be negative electrode active materials that can greatly improve the capacity of nonaqueous electrolyte secondary batteries. Since these simple substances can absorb and release a large number of charge carriers (lithium ions, etc.) per unit volume (mass), they become high-capacity negative electrode active materials. Here, it is preferable to use simple Si as the silicon-based negative electrode active material. Similarly, it is also preferable to use a silicon oxide such as SiO _x (0.3≦x≦1.6) that is disproportionated into two phases, a Si phase and a silicon oxide phase. At this time, the range of x is more preferably 0.5≦x≦1.5, and even more preferably 0.7≦x≦1.2. Furthermore, an alloy containing silicon (silicon-containing alloy negative electrode active material) may be used. On the other hand, examples of negative electrode active materials containing the tin element (tin-based negative electrode active materials) include Sn alone, tin alloys (Cu--Sn alloys, Co--Sn alloys), amorphous tin oxides, tin-silicon oxides, and the like. Among these, SnB _0.4 P _0.6 O _3.1 is exemplified as the amorphous tin oxide. Moreover, SnSiO ₃ is exemplified as the tin silicon oxide. Furthermore, a metal containing lithium may be used as the negative electrode active material. Such a negative electrode active material is not particularly limited as long as it is an active material containing lithium, and examples thereof include metal lithium and lithium-containing alloys. Examples of lithium-containing alloys include alloys of Li and at least one of In, Al, Si, and Sn. In some cases, two or more types of negative electrode active materials may be used together. Note that, of course, negative electrode active materials other than those mentioned above may be used. The present invention exhibits particularly excellent effects when the negative electrode active material expands and contracts significantly during charging and discharging. From this point of view and in terms of high capacity, the negative electrode active material preferably contains metallic lithium, a silicon-based negative electrode active material, or a tin-based negative electrode active material, and particularly preferably contains metallic lithium.

Examples of the shape of the negative electrode active material include particulate (spherical, fibrous), thin film, and the like. When the negative electrode active material has a particle shape, the average particle size (D ₅₀ ) is, for example, preferably within the range of 1 nm to 100 μm, more preferably within the range of 10 nm to 50 μm, and even more preferably 100 nm. 20 μm, particularly preferably 1 to 20 μm. Note that in this specification, the value of the average particle diameter (D ₅₀ ) of the active material can be measured by a laser diffraction scattering method.

The content of the negative electrode active material in the negative electrode active material layer is not particularly limited, but for example, it is preferably within the range of 40 to 99% by mass, and preferably within the range of 50 to 90% by mass. More preferred.

Preferably, the negative electrode active material layer further includes a solid electrolyte. By including the solid electrolyte in the negative electrode active material layer, the ionic conductivity of the negative electrode active material layer can be improved. Examples of the solid electrolyte include sulfide solid electrolytes and oxide solid electrolytes, and sulfide solid electrolytes are preferred.

Examples of the sulfide solid electrolyte include LiI-Li ₂ S-SiS ₂ , LiI-Li ₂ SP ₂ O ₅ , LiI-Li ₃ PO ₄ -P ₂ S ₅ , Li ₂ SP ₂ S ₅ , LiI-Li ₃ PS ₄ , LiI-LiBr-Li ₃ PS _4, Li ₃ PS _4, Li ₂ SP ₂ S ₅ , Li ₂ SP ₂ S ₅ -LiI, Li ₂ SP ₂ S ₅ - Li ₂ O, Li ₂ S-P ₂ S ₅ -Li ₂ O-LiI, Li ₂ S-SiS ₂ , Li ₂ S-SiS ₂ -LiI, Li ₂ S-SiS ₂ -LiBr, Li ₂ S-SiS ₂ -LiCl, Li ₂ S-SiS ₂ -B ₂ S ₃ -LiI, Li ₂ S-SiS ₂ -P ₂ S ₅ -LiI, Li ₂ S-B ₂ S ₃ , Li ₂ S-P ₂ S ₅ -Z _m S _n (where m and n are positive numbers, and Z is either Ge, Zn, or Ga), Li ₂ S-GeS ₂ , Li ₂ S-SiS ₂ -Li ₃ PO ₄ , Li ₂ S-SiS ₂ -Li _x MO _y (where x and y are positive numbers, and M is any one of P, Si, Ge, B, Al, Ga, In), etc. . Note that the description “Li ₂ SP ₂ S ₅ ” means a sulfide solid electrolyte made using a raw material composition containing Li ₂ S and P ₂ S ₅ , and the same applies to other descriptions.

The sulfide solid electrolyte may have, for example, a Li ₃ PS ₄ skeleton, a Li ₄ P ₂ S ₇ skeleton, or a Li ₄ P ₂ S ₆ skeleton. . Examples of the sulfide solid electrolyte having a Li ₃ PS ₄ skeleton include LiI-Li ₃ PS ₄ , LiI-LiBr-Li ₃ PS _{4, and} Li ₃ PS ₄ . Furthermore, examples of the sulfide solid electrolyte having a Li ₄ P ₂ S ₇ skeleton include a Li--P--S solid electrolyte (eg, Li ₇ P ₃ S ₁₁ ) called LPS. Further, as the sulfide solid electrolyte, for example, LGPS expressed by Li _(4-x) Ge _(1-x) P _x S ₄ (x satisfies 0<x<1) or the like may be used. Among these, the sulfide solid electrolyte is preferably a sulfide solid electrolyte containing the element P, and more preferably the sulfide solid electrolyte is a material containing Li ₂ SP ₂ S ₅ as a main component. Furthermore, the sulfide solid electrolyte may contain halogen (F, Cl, Br, I).

In addition, when the sulfide solid electrolyte is Li ₂ S-P ₂ S ₅ system, the ratio of Li ₂ S and P ₂ S ₅ is a molar ratio of Li ₂ S:P ₂ S ₅ =50:50 to 100. :0, and particularly preferably Li ₂ S:P ₂ S ₅ =70:30 to 80:20.

Further, the sulfide solid electrolyte may be sulfide glass, crystallized sulfide glass, or a crystalline material obtained by a solid phase method. Note that sulfide glass can be obtained, for example, by performing mechanical milling (ball mill, etc.) on a raw material composition. Further, crystallized sulfide glass can be obtained, for example, by heat-treating sulfide glass at a temperature equal to or higher than the crystallization temperature. Further, the ionic conductivity (for example, Li ion conductivity) of the sulfide solid electrolyte at room temperature (25° C.) is preferably 1×10 ⁻⁵ S/cm or more, and 1×10 ⁻⁴ S/cm or more. More preferably, it is at least cm. Note that the ionic conductivity value of the solid electrolyte can be measured by an AC impedance method.

Examples of the oxide solid electrolyte include compounds having a NASICON type structure. Examples of compounds having a NASICON type structure include a compound represented by the general formula Li _1+x Al _x Ge _2-x (PO ₄ ) ₃ (0≦x≦2) (LAGP), and a general formula Li _1+x Al _x Ti _{2 -x} (PO ₄ ) ₃ (0≦x≦2) (LATP) and the like. In addition, other examples of oxide solid electrolytes include LiLaTiO (e.g., Li _0.34 La _0.51 TiO ₃ ), LiPON (e.g., Li _2.9 PO _3.3 N _0.46 ), LiLaZrO (e.g. , Li ₇ La ₃ Zr ₂ O ₁₂ ), and the like.

Examples of the shape of the solid electrolyte include particle shapes such as true spheres and ellipsoids, thin film shapes, and the like. When the solid electrolyte has a particle shape, its average particle diameter (D ₅₀ ) is not particularly limited, but is preferably 40 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. On the other hand, the average particle diameter (D ₅₀ ) is preferably 0.01 μm or more, more preferably 0.1 μm or more.

The content of the solid electrolyte in the negative electrode active material layer is, for example, preferably in the range of 1 to 60% by mass, more preferably in the range of 10 to 50% by mass.

In addition to the above-described negative electrode active material and solid electrolyte, the negative electrode active material layer may further contain at least one of a conductive additive and a binder.

Examples of conductive aids include metals such as aluminum, stainless steel (SUS), silver, gold, copper, and titanium; alloys or metal oxides containing these metals; carbon fibers (specifically, vapor-grown carbon fibers); (VGCF), polyacrylonitrile carbon fiber, pitch carbon fiber, rayon carbon fiber, activated carbon fiber, etc.), carbon nanotubes (CNT), carbon black (specifically, acetylene black, Ketjen black (registered trademark)) , furnace black, channel black, thermal lamp black, etc.), but are not limited to these. Further, a particulate ceramic material or resin material coated with the above metal material by plating or the like can also be used as a conductive aid. Among these conductive additives, from the viewpoint of electrical stability, it is preferable to include at least one selected from the group consisting of aluminum, stainless steel, silver, gold, copper, titanium, and carbon; , silver, gold, and carbon, and more preferably carbon. These conductive aids may be used alone or in combination of two or more.

The shape of the conductive aid is preferably particulate or fibrous. When the conductive additive is in the form of particles, the shape of the particles is not particularly limited, and may be any shape such as powder, sphere, rod, needle, plate, column, irregular shape, flake, spindle, etc. I don't mind.

The average particle diameter (primary particle diameter) when the conductive additive is in the form of particles is not particularly limited, but from the viewpoint of the electrical characteristics of the battery, it is preferably 0.01 to 10 μm. In addition, in this specification, "particle diameter of a conductive aid" means the maximum distance L among the distances between arbitrary two points on the outline of a conductive aid. The value of the "average particle diameter of the conductive aid" is the particle diameter of particles observed in several to several dozen fields of view using observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The value calculated as the average value shall be adopted.

When the negative electrode active material layer contains a conductive additive, the content of the conductive additive in the negative electrode active material layer is not particularly limited, but is preferably 0 to 10% by mass based on the total mass of the negative electrode active material layer. , more preferably 2 to 8% by weight, and still more preferably 4 to 7% by weight. Within this range, it becomes possible to form a stronger electron conduction path in the negative electrode active material layer, and it is possible to effectively contribute to improving battery characteristics.

On the other hand, the binder is not particularly limited, but examples include the following materials.

Polybutylene terephthalate, polyethylene terephthalate, polyvinylidene fluoride (PVDF) (including compounds in which hydrogen atoms are substituted with other halogen elements), polyethylene, polypropylene, polymethylpentene, polybutene, polyethernitrile, polytetrafluoroethylene, Polyacrylonitrile, polyimide, polyamide, ethylene-vinyl acetate copolymer, polyvinyl chloride, styrene-butadiene rubber (SBR), ethylene-propylene-diene copolymer, styrene-butadiene-styrene block copolymer and hydrogenated products thereof , thermoplastic polymers such as styrene/isoprene/styrene block copolymers and their hydrogenated products, tetrafluoroethylene/hexafluoropropylene copolymers (FEP), tetrafluoroethylene/perfluoroalkyl vinyl ether copolymers (PFA) , fluororesins such as ethylene/tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene/chlorotrifluoroethylene copolymer (ECTFE), polyvinyl fluoride (PVF), vinylidene fluoride- Hexafluoropropylene-based fluororubber (VDF-HFP-based fluororubber), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene-based fluororubber (VDF-HFP-TFE-based fluororubber), vinylidene fluoride-pentafluoropropylene-based fluororubber (VDF-PFP-based fluororubber), vinylidene fluoride-pentafluoropropylene-tetrafluoroethylene-based fluororubber (VDF-PFP-TFE-based fluororubber), vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene-based fluororubber ( Examples include vinylidene fluoride-based fluororubbers such as VDF-PFMVE-TFE-based fluororubber), vinylidene fluoride-chlorotrifluoroethylene-based fluororubber (VDF-CTFE-based fluororubber), and epoxy resins. Among these, polyimide, styrene-butadiene rubber, carboxymethyl cellulose, polypropylene, polytetrafluoroethylene, polyacrylonitrile, and polyamide are more preferred.

The thickness of the negative electrode active material layer varies depending on the structure of the intended all-solid-state battery, but is preferably within the range of 0.1 to 1000 μm, for example.

[Cathode active material layer]
The positive electrode active material layer preferably contains a positive electrode active material containing sulfur. The type of positive electrode active material containing sulfur is not particularly limited, but in addition to elemental sulfur (S), particles or thin films of organic sulfur compounds or inorganic sulfur compounds may be used. Any material may be used as long as it can release lithium ions at times and occlude lithium ions during discharge. Examples of the organic sulfur compound include disulfide compounds, sulfur-modified polyacrylonitrile represented by the compound described in International Publication No. 2010/044437 pamphlet, sulfur-modified polyisoprene, rubeanic acid (dithiooxamide), polysulfide carbon, and the like. Among these, disulfide compounds, sulfur-modified polyacrylonitrile, and rubeanic acid are preferred, and sulfur-modified polyacrylonitrile is particularly preferred. As the disulfide compound, those having a dithiobiurea derivative, a thiourea group, a thioisocyanate, or a thioamide group are more preferable. Here, the sulfur-modified polyacrylonitrile is a modified polyacrylonitrile containing sulfur atoms, which is obtained by mixing sulfur powder and polyacrylonitrile and heating the mixture under an inert gas or reduced pressure. The estimated structure can be found, for example, in Chem. Mater. As shown in 2011, 23, 5024-5028, polyacrylonitrile is ring-closed to become polycyclic, and at least a part of S is bonded to C. The compound described in this document has strong peak signals near 1330 cm ^-1 and 1560 cm ^-1 in the Raman spectrum, and peaks near 307 cm ^-1 , 379 cm ^-1 , 472 cm ^-1 , and 929 cm ^-1 do. On the other hand, inorganic sulfur compounds are preferable because of their excellent stability, and specifically, sulfur element (S), S-carbon composite, TiS ₂ , TiS ₃ , TiS ₄ , NiS, NiS ₂ , CuS, FeS ₂ , Li ₂ S, MoS ₂ , MoS ₃ , and the like. Among these, S, S-carbon composite, TiS ₂ , TiS ₃ , TiS ₄ , FeS ₂ and MoS ₂ are preferred, elemental sulfur (S), S-carbon composite, TiS ₂ and FeS 2 are more preferred, and elemental sulfur (S), S-carbon composite, TiS 2 and FeS ₂ are more preferred; S) is particularly preferred. Here, the S-carbon composite includes sulfur powder and a carbon material, and is in a composite state by subjecting them to heat treatment or mechanical mixing. In more detail, sulfur is distributed on the surface and within the pores of carbon materials, sulfur and carbon materials are uniformly dispersed at the nano level, and they aggregate to form particles, fine sulfur This is a state in which carbon material is distributed on the surface or inside of the powder, or a state in which a plurality of these states are combined.

The positive electrode active material layer may include a sulfur-free positive electrode active material instead of the sulfur-containing positive electrode active material. Examples of sulfur-free positive electrode active materials include layered rock salt active materials such as LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , LiVO ₂ , and Li(Ni-Mn-Co)O ₂ , LiMn ₂ O ₄ , LiNi _0. Examples include spinel-type active materials such as ₅ Mn _1.5 O ₄ , olivine-type active materials such as LiFePO ₄ and LiMnPO ₄ , and Si-containing active materials such as Li ₂ FeSiO ₄ and Li ₂ MnSiO ₄ . Further, examples of oxide active materials other than those mentioned above include Li ₄ Ti ₅ O ₁₂ .

In some cases, two or more types of positive electrode active materials may be used together. Note that, of course, positive electrode active materials other than those mentioned above may be used.

Examples of the shape of the positive electrode active material include particulate (spherical, fibrous), thin film, and the like. When the positive electrode active material is in the form of particles, the average particle size (D ₅₀ ) is, for example, preferably within the range of 1 nm to 100 μm, more preferably within the range of 10 nm to 50 μm, and even more preferably 100 nm. 20 μm, particularly preferably 1 to 20 μm. Note that in this specification, the value of the average particle diameter (D ₅₀ ) of the active material can be measured by a laser diffraction scattering method.

The content of the positive electrode active material in the positive electrode active material layer is not particularly limited, but for example, it is preferably within the range of 40 to 99% by mass, and preferably within the range of 50 to 90% by mass. More preferred.

The positive electrode active material layer may also further contain a conductive additive and/or a binder, similar to the negative electrode active material layer.

[Solid electrolyte layer]
In the all-solid lithium ion secondary battery according to this embodiment, the solid electrolyte layer is a layer that contains a solid electrolyte as a main component and is interposed between the above-described positive electrode active material layer and negative electrode active material layer. Since the specific form of the solid electrolyte contained in the solid electrolyte layer is the same as that described above, detailed explanation will be omitted here. The solid electrolyte layer may further contain a binder in addition to the solid electrolyte described above. Since the specific form of the binder that can be contained in the solid electrolyte layer is the same as that described above, detailed explanation will be omitted here.

The all-solid-state lithium ion secondary battery according to this embodiment is characterized in that the solid electrolyte layer has an electrodeposition growth inhibiting layer containing a solid material having a higher electrode potential than metallic lithium.

There are no particular limitations on the solid material having a higher electrode potential than metallic lithium, and any material that has a higher electrode potential than metallic lithium and exists in a solid state at the operating temperature of the battery may be used. Examples of the solid materials include metals such as aluminum, stainless steel (SUS), silver, gold, copper, and titanium; alloys or metal oxides containing these metals; graphite and carbon fiber (specifically is vapor grown carbon fiber (VGCF), polyacrylonitrile carbon fiber, pitch carbon fiber, rayon carbon fiber, activated carbon fiber, etc.), carbon nanotube (CNT), carbon black (specifically, acetylene black, Examples include carbon materials such as Ketjen Black (registered trademark), furnace black, channel black, thermal lamp black, etc.). Alternatively, a ceramic material or a resin material coated with the metal material by plating or the like may be used. Furthermore, layered rock salts such as Li ₄ Ti ₅ O ₁₂ (lithium titanate), Li ₂ TiO ₃ (lithium metatitanate), LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , LiVO ₂ , and Li(Ni-Mn-Co)O ₂ type oxides, spinel type oxides such as LiMn ₂ O ₄ and LiNi _0.5 Mn _1.5 O ₄ , olivine type oxides such as LiFePO ₄ and LiMnPO ₄ , and lithium oxides such as Li ₂ FeSiO ₄ and Li ₂ MnSiO ₄ (lithium-containing metal oxide) can also be used as the solid material. Among these, from the viewpoint of making it possible to control the determination of the presence or absence of electrodeposition, which will be described later, a conductive material is preferably used, and a carbon material is more preferably used. Note that when a certain material is "a solid material", it means that the material exists in a solid state at the operating temperature of the battery. In addition, when a material is said to have a higher electrode potential than metallic lithium, it means that the standard electrode potential value with reference to the hydrogen standard electrode (HSE) is higher than that of metallic lithium (-3.045V). It means big.

There is no particular restriction on the form in which the solid electrolyte layer includes the electrodeposition growth inhibiting layer. For example, the solid electrolyte layer may include the solid material in a dispersed state throughout the solid electrolyte layer, so that the entire solid electrolyte layer is configured as an electrodeposition growth inhibiting layer. However, from the viewpoint of minimizing the amount of solid material used to reduce manufacturing costs and increasing the content ratio of solid electrolyte constituting the solid electrolyte layer, the electrodeposition growth inhibiting layer should not contain the above-mentioned solid material. It is preferable that the solid electrolyte layer be included in the solid electrolyte layer as a separate layer from the layer containing the solid electrolyte (herein also referred to as "sub-solid electrolyte layer"). An example of such a configuration is a configuration in which an electrodeposition growth suppression layer is sandwiched between a pair of sub-solid electrolyte layers, as in the embodiment shown in FIG.

Here, in the embodiment shown in FIG. 3, the sub solid electrolyte layers (17a, 17c) may have the same composition as a conventionally known solid electrolyte layer. On the other hand, it is preferable that the electrodeposition growth inhibiting layer 17b contains the above solid material together with a solid electrolyte. With such a configuration, lithium ions can be transferred smoothly between the positive and negative electrodes via the solid electrolyte layer during charging and discharging of the battery without being blocked by the presence of the electrodeposition growth inhibiting layer. .

Another preferred embodiment in which the solid electrolyte layer is composed of an electrodeposition growth inhibiting layer and a pair of sub-solid electrolyte layers is the embodiment shown in FIG. 4. In FIG. 4, at least a part of the outer peripheral edge of the electrodeposition growth suppression layer 17b protrudes toward the negative electrode active material layer 15, thereby forming a second sub-solid electrolyte layer located on the negative electrode active material layer 15 side. It is configured to cover the outer periphery of 17c. Since the generation of dendrites made of metallic lithium due to electrodeposition is particularly likely to occur at the outer peripheral edge of the negative electrode active material layer 15, according to the embodiment shown in FIG. This is preferable because the growth of dendrites and the occurrence of internal short circuits caused by this can be more reliably prevented.

When the solid material constituting the electrodeposition growth inhibiting layer is a conductive material, the solid electrolyte layer preferably includes a structure in which the solid material is three-dimensionally connected. As an example of such a form, as in the embodiment shown in FIG. 3, the electrodeposition growth inhibiting layer includes conductive fibers, and the conductive fibers are in electrical contact with each other as the electrodeposition growth inhibiting layer. An example is a form in which a structure is formed. However, the present invention is not limited to such a configuration, and the solid material constituting the electrodeposition growth inhibiting layer may have a shape such as a mesh or expanded metal to constitute a three-dimensionally connected structure. In any of the above-mentioned forms, the solid material forms the electrodeposition growth inhibiting layer together with the solid electrolyte, so that the exchange of lithium ions between the positive and negative electrodes via the solid electrolyte layer during charging and discharging of the battery is prevented by electrodeposition. It can be prevented from being blocked by the growth inhibiting layer.

The thickness of the solid electrolyte layer varies depending on the structure of the intended all-solid-state battery, but for example, it is preferably within the range of 0.1 to 1000 μm, including the thickness of the electrodeposition growth inhibiting layer. More preferably, the thickness is within the range of 1 to 300 μm. Furthermore, the effects of the present invention can be more pronounced as the thickness of the solid electrolyte layer becomes smaller. Therefore, the thickness of the solid electrolyte layer, including the thickness of the electrodeposition growth inhibiting layer, is preferably 0.1 to 100 μm, more preferably 0.1 to 50 μm.

Hereinafter, with reference to FIG. 5, a method for manufacturing a solid electrolyte layer (solid electrolyte layer for an all-solid lithium ion secondary battery) used in an all-solid-state battery according to one embodiment of the present invention will be described. FIG. 5 is an explanatory diagram for explaining a method for manufacturing the solid electrolyte layer 17 according to the embodiment shown in FIG.

Referring to FIG. 5, the method for manufacturing the solid electrolyte layer 17 according to the embodiment shown in FIG. Producing a sub-solid electrolyte layer 17a) located on the positive electrode active material layer side (step S11), and applying a solid electrolyte material to the exposed surface of at least one of the first sub-solid electrolyte layer (sub-solid electrolyte layer 17a). and powder forming a solid material having a higher electrode potential than metallic lithium to produce a sheet-like electrodeposition growth inhibiting layer 17b (step S12), and on the exposed surface of the electrodeposition growth inhibiting layer 17b, The step S13 includes compacting the solid electrolyte material to produce a sheet-like second sub-solid electrolyte layer (sub-solid electrolyte layer 17c located on the negative electrode active material layer side). According to the manufacturing method having such a configuration, a solid electrolyte layer for an all-solid-state lithium ion secondary battery including an electrodeposition growth inhibiting layer having a desired configuration can be manufactured by a simple method.

Here, as the solid electrolyte material used in steps S11 to S13, conventionally known materials are similarly employed, and specific examples thereof are also as described above. Furthermore, the "solid material having a higher electrode potential than metallic lithium" used in step S12 is also as described above. In this specification, "powder compacting" refers to a molding method in which a powdered raw material is filled into a mold and then pressure-molded. At this time, during pressure molding, the raw material or the object to be formed may be heated within a range that does not adversely affect the object to be formed. However, preferably, pressure molding is performed without heating the raw material or the object to be molded.

After the solid electrolyte layer 17 used in the all-solid lithium ion secondary battery is obtained through steps S11 to S13 shown in FIG. 5 described above, each surface of the solid electrolyte layer 17 is A positive electrode active material layer 13 and a negative electrode active material layer 15 can be formed thereon. Specifically, first, a positive electrode mixture constituting a positive electrode active material layer is powder-molded on the surface of one sub-solid electrolyte layer 17a constituting the solid electrolyte layer 17 obtained in steps S11 to S13 described above. Then, a sheet-like positive electrode active material layer 13 is produced (step S14). At this time, the positive electrode mixture may include, in addition to the positive electrode active material, a solid electrolyte material, a conductive additive, a binder, and the like. Subsequently, the negative electrode mixture constituting the negative electrode active material layer is powder-molded on the surface of the other sub-solid electrolyte layer 17c constituting the laminate obtained in step S14 described above to form a sheet-like negative electrode active material layer. A material layer 15 is produced (step S15). At this time, the negative electrode mixture may include, in addition to the negative electrode active material, a solid electrolyte material, a conductive additive, a binder, and the like. Finally, the positive electrode current collector 11 is bonded to the exposed surface of the positive electrode active material layer 13, and the negative electrode current collector 12 is bonded to the exposed surface of the negative electrode active material layer 15. Thereby, the unit cell layer 19 according to the embodiment shown in FIG. 3 can be manufactured.

Hereinafter, with reference to FIG. 6, a method for manufacturing a solid electrolyte layer (solid electrolyte layer for an all-solid lithium ion secondary battery) used in an all-solid-state battery according to one embodiment of the present invention will be described. FIG. 6 is an explanatory diagram for explaining a method of manufacturing the solid electrolyte layer 17 according to the embodiment shown in FIG.

Referring to FIG. 6, the method for manufacturing the solid electrolyte layer 17 according to the embodiment shown in FIG. Producing a sub-solid electrolyte layer 17a) located on the positive electrode active material layer side (step S21), and applying a solid electrolyte material to the exposed surface of at least one of the first sub-solid electrolyte layer (sub-solid electrolyte layer 17a). and pre-compacting a solid material having a higher electrode potential than metallic lithium to produce a sheet-like precursor 17b' of the electrodeposition growth inhibiting layer (step S22); The electrodeposition growth inhibiting layer 17b having a concave portion surrounded by at least a portion of the outer circumferential edge is formed by compacting a portion excluding at least a portion of the outer circumferential edge (step S23); A solid electrolyte material is compacted into the concave portion of the growth inhibiting layer 17b, and a second sub-solid electrolyte layer (containing negative electrode active material and producing a sub-solid electrolyte layer 17c) located on the layer side (S24).

Here, the "preliminary powder compacting" in step S22 is performed prior to the "main compacting" in step S23. In the powder compaction preliminary molding in step S22, the compacting pressure is set lower than that in the powder compaction main molding in step S23. Thereby, when the main compacting process is performed in step S23, the thickness of the electrodeposition growth inhibiting layer 17b can be reduced in the area where the main forming process has been performed. For this reason, by performing powder compaction processing on the region excluding at least a part of the outer peripheral edge of the precursor 17b' of the electrodeposition growth inhibiting layer, the electrodeposition having the shape shown in FIGS. 4 and 6 is formed. Thus, the growth inhibiting layer 17b can be produced.

Once the solid electrolyte layer 17 used in the all-solid-state lithium ion secondary battery is obtained through steps S21 to S24 shown in FIG. 6 described above, each active material layer and each current collector are arranged using the same method as above. By doing so, the unit cell layer 19 according to the embodiment shown in FIG. 4 can be manufactured (steps S25 to S26).

[Positive current collector plate and negative current collector plate]
The material constituting the current collector plates (25, 27) is not particularly limited, and known highly conductive materials conventionally used as current collector plates for secondary batteries may be used. As the constituent material of the current collector plate, for example, metal materials such as aluminum, copper, titanium, nickel, stainless steel (SUS), and alloys thereof are preferable. From the viewpoints of light weight, corrosion resistance, and high conductivity, aluminum and copper are more preferred, and aluminum is particularly preferred. Note that the positive electrode current collector plate 27 and the negative electrode current collector plate 25 may use the same material or different materials.

[Positive lead and negative lead]
Although not shown, the current collectors (11, 12) and the current collector plates (25, 27) may be electrically connected via a positive lead or a negative lead. As constituent materials for the positive electrode and negative electrode leads, materials used in known lithium ion secondary batteries can be similarly employed. In addition, the parts taken out from the exterior are covered with heat-resistant insulating heat-shrinkable material to prevent them from contacting peripheral equipment or wiring and causing electrical leakage, which may affect products (e.g., automobile parts, especially electronic equipment, etc.). Preferably, it is covered with a tube or the like.

[Battery exterior material]
As the battery exterior material, a well-known metal can case can be used, or a bag-shaped case using a laminate film 29 containing aluminum that can cover the power generation element as shown in FIGS. 1 and 2 can be used. It can be done. The laminate film may be, for example, a laminate film having a three-layer structure in which PP, aluminum, and nylon are laminated in this order, but is not limited thereto. A laminate film is desirable from the viewpoint that it has high output and excellent cooling performance, and can be suitably used in batteries for large equipment such as EVs and HEVs. Moreover, the exterior body is more preferably a laminate film containing aluminum because the group pressure applied to the power generation element from the outside can be easily adjusted.

The stacked battery according to this embodiment has a configuration in which a plurality of cell layers are connected in parallel, and thus has high capacity and excellent cycle durability. Therefore, the stacked battery according to this embodiment is suitably used as a power source for driving EVs and HEVs.

Although one embodiment of the all-solid-state battery has been described above, the present invention is not limited to only the configuration described in the embodiment described above, and can be modified as appropriate based on the description of the claims. be.

For example, in the embodiments shown in FIGS. 2 to 4, all of the plurality of solid electrolyte layers 17 have the electrodeposition growth inhibiting layer 17b. However, in a battery including a plurality of solid electrolyte layers, it is within the technical scope of the present invention as long as at least one solid electrolyte layer has an electrodeposition growth inhibiting layer.

In the embodiment shown in FIG. 4, the outer peripheral edge of the solid electrolyte layer 17 protrudes toward the negative electrode active material layer 15 over the entire outer periphery of the solid electrolyte layer 17, so that the outer peripheral edge of the solid electrolyte layer 17 is located on the negative electrode active material layer 15 side. The solid electrolyte layer 17c is configured to cover the outer periphery of the sub-solid electrolyte layer 17c. With such a configuration, it is possible to more reliably prevent the growth of dendrites generated at the outer peripheral edge of the negative electrode active material layer 15 and the occurrence of internal short circuits caused by this. However, the present invention is not limited to such a configuration, and the outer peripheral edge of the solid electrolyte layer 17 protrudes toward the negative electrode active material layer 15 to form a sub-solid electrolyte located on the negative electrode active material layer 15 side. It is sufficient that the portion covering the outer periphery of the layer 17c exists at least in part of the outer periphery of the solid electrolyte layer.

[Assembled battery]
A battery pack is made up of multiple batteries connected together. Specifically, it is configured by using at least two or more, serially or parallelly, or both. By connecting them in series or parallel, it becomes possible to freely adjust the capacity and voltage.

A plurality of batteries can be connected in series or in parallel to form a small detachable battery pack. By connecting multiple small, removable battery packs in series or in parallel, high-capacity, high-capacity power supplies suitable for vehicle drive power sources and auxiliary power sources that require high volumetric energy density and high volumetric power density can be created. It is also possible to form an assembled battery (battery module, battery pack, etc.) that has an output. How many batteries to connect to make a battery pack, and how many stages of small battery packs to stack to make a large-capacity battery pack depends on the battery capacity of the vehicle (electric vehicle) in which it will be mounted. You can decide according to the output.

[vehicle]
A battery or a battery pack made by combining a plurality of batteries can be mounted on a vehicle. In the present invention, it is possible to configure a long-life battery with excellent long-term reliability, so when such a battery is installed, a plug-in hybrid electric vehicle with a long EV mileage or an electric vehicle with a long mileage per charge can be configured. Batteries or assembled batteries made by combining multiple of these can be used, for example, in the case of automobiles, such as hybrid vehicles, fuel cell vehicles, electric vehicles (all four-wheeled vehicles (passenger cars, commercial vehicles such as trucks, buses, light vehicles, etc.), etc. , two-wheeled vehicles (including motorcycles, and three-wheeled vehicles)) can provide long-life and highly reliable vehicles. However, the application is not limited to automobiles; for example, it can be applied to various power sources for other vehicles, such as trains, and on-board power sources such as uninterruptible power supplies. It is also possible to use it as

《All-solid-state lithium-ion secondary battery system》
According to yet another aspect of the present invention, an all-solid-state lithium-ion secondary battery system including the above-described all-solid-state lithium-ion secondary battery is also provided.

The all-solid-state lithium ion secondary battery system according to this embodiment includes the above-described all-solid-state lithium ion secondary battery according to one embodiment of the present invention, and an impedance measuring section that measures AC impedance of the all-solid lithium ion secondary battery. Based on the capacity (electric double layer) component of the negative electrode calculated from the AC impedance measured by the impedance measuring section, the electrodeposition of metallic lithium generated in the negative electrode active material layer of the all-solid-state lithium ion secondary battery is determined. The apparatus further includes a control section that determines whether or not the electrodeposition growth inhibiting layer has been reached.

FIG. 7 is a block diagram for explaining the configuration of an all-solid-state lithium ion secondary battery system according to an embodiment of the present invention.

This all-solid lithium ion secondary battery system (hereinafter also referred to as "secondary battery system 1") includes an all-solid lithium ion secondary battery (hereinafter also referred to as "secondary battery 2"). Then, charging power is supplied to the voltage sensor 3 that measures the cell voltage (voltage between terminals) of the secondary battery 2, the temperature sensor 4 that measures the outer surface temperature (environmental temperature) of the secondary battery 2, and the secondary battery 2. A voltage and current adjustment section 5, a current sensor 6 that measures the charging and discharging current of the secondary battery 2, an impedance measuring section 7 that measures the AC impedance of the secondary battery 2, and a control section 8 that controls the charging and discharging of the secondary battery 2. Be prepared. Further, the voltage and current adjustment unit 5 is connected to an external power supply 9 and receives power during charging, while discharging to the external power supply 9 via the voltage and current adjustment unit 5 during discharging (details will be described later).

The details of each part will be explained below.

The secondary battery 2 is an all-solid-state lithium ion secondary battery according to one embodiment of the present invention described above, in that the solid electrolyte layer has an electrodeposition growth inhibiting layer containing a solid material having a higher electrode potential than metallic lithium. It has characteristics. Here, the solid material that constitutes the electrodeposition growth inhibiting layer in the solid electrolyte layer of the all-solid-state lithium ion secondary battery according to this embodiment is a material that has electrical conductivity. Further, the electrodeposition growth inhibiting layer includes a structure in which the solid material made of the above-mentioned conductive material is three-dimensionally connected. By constructing an all-solid-state lithium-ion secondary battery system using an all-solid-state lithium-ion secondary battery having such a configuration, the negative electrode capacity (electrical secondary battery) calculated from the AC impedance of the all-solid-state lithium-ion secondary battery can be Based on the multilayer component, it can be determined whether the electrodeposition of metallic lithium generated in the negative electrode active material layer of the all-solid-state lithium ion secondary battery has reached the electrodeposition growth inhibiting layer.

The voltage sensor 3 may be, for example, a voltmeter, and measures the cell voltage (voltage between terminals) between the positive electrode and the negative electrode of the secondary battery 2. The mounting position of the voltage sensor 3 is not particularly limited, and may be any position as long as it can measure the cell voltage between the positive electrode and the negative electrode within the circuit connected to the secondary battery 2.

Temperature sensor 4 measures the outer surface temperature (environmental temperature) of secondary battery 2 . The temperature sensor 4 is attached, for example, to the surface of the case (exterior body, housing) of the secondary battery 2. In this embodiment, the temperature of the secondary battery 2 is determined by measuring the outer surface temperature of the secondary battery 2. Although the outer surface temperature cannot accurately represent the inner temperature, it is at least almost the same as the temperature of the unit cell layer near the outermost layer of the secondary battery.

When charging the secondary battery 2, the voltage/current adjustment unit 5 adjusts the voltage and current of the power from the external power source 9 based on a command from the control unit 8, and supplies the power to the secondary battery 2. Further, when the secondary battery 2 is discharged, the voltage/current adjustment section 5 releases the electricity discharged from the secondary battery 2 to the external power source 9.

Here, the external power source 9 is a power source for electric vehicles, called a so-called power grid, used for charging electric vehicles, etc., and outputs direct current. Such a power source for an electric vehicle converts commercial power (alternating current) into direct current of the voltage and current necessary for charging the secondary battery 2 and provides it. Further, the external power source 9 is equipped with a power regeneration function, and when the secondary battery 2 discharges, it can convert direct current to alternating current and regenerate it to the commercial power source. Note that a well-known power supply with a power regeneration function may be used as a device constituting such an external power supply 9, so a detailed explanation will be omitted here (as a power supply with a power regeneration function, For example, there are those disclosed in JP-A-7-222369, JP-A-10-080067, etc.).

When the external power source 9 is not connected to an external power supply device such as a commercial power source, for example, when charging the secondary battery 2 using another externally installed secondary battery as a power source, the power discharged from the secondary battery 2 It is preferable to store the battery in another secondary battery. This can reduce energy waste.

The current sensor 6 is, for example, an ammeter. The current sensor 6 measures the current value of the power supplied from the voltage/current adjustment unit 5 to the secondary battery 2 when charging the secondary battery 2, and the current value of the power supplied from the secondary battery 2 to the voltage/current adjustment unit 5 during discharging. Measures the power current value. The mounting position of the current sensor 6 is not particularly limited, and it may be placed in a circuit that supplies power from the voltage/current adjustment unit 5 to the secondary battery 2 and can measure current values during charging and discharging. good.

The impedance measuring section 7 is configured to measure the AC impedance of the secondary battery 2. Therefore, as long as the impedance measurement unit 7 can measure the AC impedance of the secondary battery 2, it may be connected to a single cell of the secondary battery 2, or it may be connected to a plurality of single cells electrically connected to each other. Depending on the situation, the battery module may be connected to a battery module housed in a case, or multiple battery modules may be electrically connected and further connected to a battery pack housed in a case as necessary. good. Such an impedance measuring section 7 can be arbitrarily selected from those commonly used as general AC impedance measuring devices. For example, the impedance measuring section 7 may measure the impedance of the battery at a plurality of frequencies using an AC impedance method. The measurement method in the AC impedance method is not particularly limited. For example, analog methods such as the Lissajous method and the AC bridge method, and digital methods such as the digital Fourier integral method and the fast Fourier transform method using noise application may be appropriately employed. The plurality of frequencies measured by the impedance measurement section 7 may be within a range that allows the value of the capacity (electric double layer) component of the negative electrode of the secondary battery 2 to be calculated. For example, the plurality of frequencies are typically about 1 MHz to 0.1 Hz, preferably about 1 kHz to 0.1 Hz. Thereby, the value of the capacitance (electric double layer) component of the negative electrode can be calculated with high precision. There is no particular restriction on the amplitude of the alternating current signal applied to the battery, and it can be set as appropriate. The AC impedance measurement result measured by the impedance measurement section 7 is sent to the control section 8 as an output of the impedance measurement section 7 .

The control unit 8 is a so-called computer that includes, for example, a CPU 81 and a storage unit 82. The control unit 8 determines whether metal lithium is electrodeposited in the negative electrode active material layer of the secondary battery 2 (preferably when charging the secondary battery 2) according to the procedure described below. Implement. Furthermore, when performing this determination when performing charging processing on the secondary battery 2, the control unit 8 determines that metal lithium electrodeposition has occurred in the negative electrode active material layer of the secondary battery 2. Sometimes, the conditions of the charging process are changed so that the electrodeposition is less likely to occur (electrodeposition detection control). As such a control unit 8, in an electric vehicle, for example, an ECU (Electronic Control Unit) or the like may be used.

Here, the storage unit 82 includes a nonvolatile memory in addition to a RAM that the CPU 81 uses as a working area. The non-volatile memory stores a program for determining whether or not electrodeposition has occurred, controlling when electrodeposition is detected, etc. in this embodiment. Furthermore, the storage unit 82 stores the value of the capacity (electric double layer) component of the negative electrode of the secondary battery 2 calculated by the control unit 8 over time.

[Charging process]
The procedure of charging processing in the secondary battery system 1 configured in this way will be explained.

This charging process is performed in a state where the secondary battery system 1 is connected to the external power supply 9 and charging power can be supplied to the secondary battery 2. Furthermore, the charging process in this embodiment is controlled by a constant current charging method until the voltage of the secondary battery 2 reaches a predetermined voltage, and after the voltage of the secondary battery 2 reaches a predetermined voltage, a constant voltage charging method is used. A constant current/constant voltage (CC-CV) charging method is used.

In the charging process in this embodiment, when charging the secondary battery 2, the AC impedance (complex impedance) of the secondary battery 2 is measured, and the capacity of the negative electrode (electric double layer ) Based on the components, it is determined whether metal lithium electrodeposition has occurred in the negative electrode active material layer of the secondary battery 2, and when it is determined that the electrodeposition has occurred, the electrodeposition has occurred. The charging process conditions are changed to make it more difficult to charge. Note that this charging process is performed by the control unit 8 unless otherwise specified. The procedure of this charging process will be explained below with reference to FIG. FIG. 8 is a flowchart showing the procedure of charging processing in the secondary battery system 1.

First, the control unit 8 acquires the current temperature from the temperature sensor 4 and the current voltage from the voltage sensor 3 (S101).

Subsequently, the control unit 8 starts controlling the charging process of the secondary battery 2. Specifically, power is introduced from the external power supply 8 to the voltage/current adjustment unit 5 to start the charging process (normally, constant current (CC) charging is started) (S102). At the same time, the control unit 8 controls the impedance measuring unit 7 to start superimposing an alternating current for measuring the alternating current impedance of the secondary battery 2 (S102). At this time, by using the principle of an AC bridge, as in the internal resistance measuring device described in Figure 2 of the International Publication No. 2012/077450 pamphlet, the superimposed current can wrap around the path that is not the measurement target. It is preferable to prevent With such a configuration, it is possible to reduce the influence of the load etc. connected to the secondary battery 2 on the AC impedance measurement results, and it is possible to measure AC impedance with high accuracy.

As described above, the charging process in this embodiment is controlled using a constant current/constant voltage (CC-CV) charging method. Therefore, after starting the charging process, the control unit 8 determines that the current voltage acquired from the voltage sensor 3 is determined in advance as an index indicating the timing of switching from constant current (CC) charging to constant voltage (CV) charging. It is determined whether the voltage is equal to or higher than a predetermined voltage (threshold voltage) (S103). If the current voltage is not equal to or higher than the threshold voltage (S103: NO), the control unit 8 continues charging using the constant current (CC) charging method (S104). In this case, the control unit 8 performs control according to the present invention (determining whether metal lithium is electrodeposited in the negative electrode active material layer of the secondary battery 2), which will be described later.

On the other hand, in step S103, if the current voltage is equal to or greater than the threshold voltage (S103: YES), the control unit 8 performs charging using the constant voltage (CV) charging method (S105). In this case, the control unit 8 determines whether the current current (charging current) acquired from the current sensor 6 is equal to or less than a predetermined current (end current) that is determined in advance as an indicator of the timing for ending constant current (CV) charging (S106). Here, if the current current (charging current) is equal to or less than the end current (S106: YES), the control unit 8 ends this process. Thereafter, the charging process is also ended as necessary.

On the other hand, in step S106, if the current current (charging current) is larger than the final current (S106: NO), the control unit 8 also performs control according to the present invention (described later) (in the negative electrode active material layer of the secondary battery 2). (determination of whether or not metal lithium electrodeposition has occurred).

When performing constant current charging of the secondary battery 2 (S104), or when performing constant voltage charging of the secondary battery 2 and the current current (charging current) is larger than the final current (S106: NO), The control unit 8 determines whether the elapsed time from the start of charging (charging time) obtained from a built-in timer (not shown) is equal to or longer than a predetermined time (first threshold time). (S107). If the charging time is not longer than the first threshold time (S107: NO), the control unit 8 repeatedly makes this determination until the charging time is equal to or longer than the first threshold time. Here, the current value is not stable at the initial stage of application of the charging current, and transient changes in the current value may affect the control (determination of presence or absence of electrodeposition) according to the present invention. The reason for performing step S107 is to improve the accuracy of determining the presence or absence of electrodeposition by eliminating this influence. Note that the specific value of the first threshold time can be set as appropriate, and is, for example, several tens to several hundred milliseconds.

Subsequently, in step S107, if the charging time exceeds the first threshold time (S107: YES), the control unit 8 calculates the elapsed time from the start of superimposition of the alternating current obtained from the built-in timer (not shown). It is determined whether (AC current superimposition time) is equal to or longer than a predetermined predetermined time (second threshold time) (S108). If the alternating current superimposition time is not longer than the second threshold time (S108: NO), the control unit 8 repeatedly performs this determination until the alternating current superimposition time becomes equal to or longer than the second threshold time. Here, regarding the alternating current that is superimposed to measure alternating current impedance, the current value is not stable at the initial stage of its application, and transient changes in the current value are caused by the control according to the present invention (with or without electrodeposition). judgment). The reason why this step S108 is performed is to improve the accuracy of determining the presence or absence of electrodeposition by eliminating this influence. Note that the specific value of the second threshold time can be set as appropriate, and is, for example, several tens to several hundred milliseconds.

Subsequently, in step S108, when the alternating current superimposition time becomes equal to or longer than the second threshold time (S108: YES), the control unit 8 calculates the negative electrode capacitance (electrical Based on the component (double layer), it is determined whether metal lithium is electrodeposited in the negative electrode active material layer of the secondary battery 2 (S109).

FIG. 9 is a subroutine flowchart of step S109 in FIG.

In the subroutine shown in FIG. 9, the control unit 8 first obtains the measurement result of the AC impedance measured by the impedance measurement unit 7 as an output of the impedance measurement unit 7. At this time, the control unit 8 uses a low-pass filter (LPF) or the like to remove noise caused by high frequency components in the output from the impedance measurement unit 7 (S201).

Next, based on the output from the impedance measurement unit 7 from which noise has been removed in step S201, the capacity (electric double layer) component (herein simply referred to as "capacity component") of the negative electrode of the secondary battery 2 is determined. is the capacitance (electric double layer) component of the negative electrode) is calculated (S202). By monitoring the occurrence of electrodeposition using the value of the capacitance (electric double layer) component of the negative electrode as an index, it is possible to detect electrodeposition that can specifically occur in the negative electrode active material layer with high accuracy. In addition, as will be described later, an electrodeposition growth inhibiting layer (herein, a three-dimensional layer containing a conductive solid material) is a characteristic structure of the solid electrolyte layer included in an all-solid-state lithium ion secondary battery according to an embodiment of the present invention. By also using a structure (having a structure in which the electrodes are connected to each other), the accuracy of detecting electrodeposition can be further improved.

Here, an equivalent circuit diagram of the secondary battery 2 is shown in FIG. As shown in FIG. 10, a positive electrode (consisting of a reaction resistance R _{act, c} and a capacitance (electric double layer) component C _{dl, c} ), an electrolyte (consisting of a resistance component R _sep ), a negative electrode (a reaction resistance R _{act, a} and a capacitance (electric double layer) component C _dl,a ). By obtaining in advance the most suitable frequency (optimum frequency) for evaluating the negative electrode characteristics of the secondary battery 2, the influence of the positive electrode on the equivalent circuit diagram can be ignored and only the negative electrode characteristics of the secondary battery 2 can be evaluated. It is possible to extract Therefore, in the following explanation, the reaction resistance (R _act,a ) and the capacitance (electric double layer) component C _dl,a ) of the negative electrode are also simply referred to as "R _act " and "C _dl ", respectively.

Here, the AC impedance Z of the secondary battery 2 calculated based on the AC current superimposed by the impedance measurement unit 7 is composed of the following real part component Z _re and imaginary part component Z _im . In addition, in the following formula, R _mem is the resistance component of the electrolyte portion. Moreover, ω is an angular frequency, and is expressed as ω=2πf using the applied frequency f.

Among these, for example, if we focus on the imaginary component Z _im of the AC impedance Z and transform it, the following equation is derived.

Here, ω is a known parameter calculated from the applied frequency, and Z _im is a known component obtained as the imaginary component of AC impedance. Therefore, the values of (1/ω ² ) and (-1/ωZ _im ) obtained from the first applied frequency (f1) and the second applied frequency (f2) are respectively plotted on the horizontal axis (x-axis) and the vertical axis ( y axis), it is possible to uniquely obtain a linear function expressed as y=ax+b. Here, the slope (a) of the linear function is a value equivalent to (1/(C _dl * (R _act ) ² ). Also, the y-intercept (b) of the linear function is equivalent to C _dl Therefore, the value of C _dl can be calculated as the value of the capacity (electric double layer) component of the negative electrode of the secondary battery 2.The capacity of the negative electrode of the secondary battery 2 calculated in this way The value of the (electric double layer) component is stored over time in the third storage section included in the storage section 82. Note that even when focusing on the real component Z _re of the AC impedance Z, a known method is used. By doing so, it is possible to calculate the value of C _dl as the capacity (electric double layer) component of the negative electrode of the secondary battery 2.

Subsequently, the control unit 8 compares the value of the capacity (electric double layer) component of the negative electrode of the secondary battery 2 calculated in step S202 with the measured value obtained by the previous measurement. Specifically, the slope (increase rate per unit time) of the value of the capacitance (electric double layer) component of the negative electrode is calculated (S203). Note that the amount of increase in the value of the capacitance (electric double layer) component of the negative electrode calculated at predetermined intervals may be calculated.

Then, the control unit 8 determines whether the slope (increase rate per unit time) of the value of the capacitance (electric double layer) component of the negative electrode calculated as described above is equal to or higher than a predetermined threshold value. It is determined whether or not (S204). In step S203, when the amount of increase in the value of the capacitance (electric double layer) component of the negative electrode calculated at predetermined intervals is calculated, it is determined whether the amount of increase is equal to or greater than a predetermined threshold value. to decide. In this way, by setting an appropriate threshold for the amount or rate of increase in the value of the capacity (electric double layer) component of the negative electrode, it is possible to accurately grasp the occurrence of metal lithium electrodeposition at this point. I can do it. Here, the value (C _dl ) of the capacitance (electric double layer) component of the negative electrode increases as the surface area of the negative electrode increases. When the dendrites of metallic lithium grown from the negative electrode active material layer by electrodeposition come into contact with the conductive solid material constituting the electrodeposition growth inhibiting layer, the negative electrode active material layer and the depositing growth inhibiting layer form dendrites of metallic lithium. electrically conductive through. This can be regarded as an apparent sudden increase in the surface area of the negative electrode, and is reflected in the AC impedance measurement results as an increase in the value of the negative electrode's capacitance (electric double layer) component. . In the control according to the present invention, the presence or absence of electrodeposition is determined using this increase in the capacity (electric double layer) component of the negative electrode as an index. That is, it can be said that the electrodeposition growth inhibiting layer not only has the function of inhibiting the growth of electrodeposition, but also has the function of a detection section (sensor) for detecting the occurrence of electrodeposition.

Here, if it is determined in step S204 that the slope (increase rate per unit time) of the value of the capacity (electric double layer) component of the negative electrode of the secondary battery 2 is less than the threshold value (S204: NO) At that point, it is determined that metal lithium is not deposited in the negative electrode active material layer of the secondary battery 2. On the other hand, if it is determined in step S204 that the slope (increase rate per unit time) of the value of the capacity (electric double layer) component of the negative electrode of the secondary battery 2 is equal to or higher than the threshold value (S204: YES), At that point, it is determined that metal lithium electrodeposition has occurred in the negative electrode active material layer of the secondary battery 2 .

Referring to the flowchart shown in FIG. 8, if it is determined in step S204 that electrodeposition has not occurred (S110: NO), the control unit 8 restarts the process from step S103. On the other hand, if it is determined in step S204 that electrodeposition has occurred (S110: YES), the control unit 8 performs electrodeposition detection control (S111).

Although the specific form of control at the time of electrodeposition detection is not particularly limited, it is preferable that the control at the time of electrodeposition detection is a process of changing the conditions of the charging process so that electrodeposition is less likely to occur.

FIG. 11 is a subroutine flowchart of step S111 (electrodeposition detection control) in FIG.

In the subroutine shown in FIG. 11, the control unit 8 first performs control to stop charging (step S301). This makes it possible to prevent further growth of dendrites caused by continuing the charging process under the same conditions even after the occurrence of electrodeposition, as well as the occurrence of internal short circuits and deterioration of the battery due to this. At this time, the user may be notified that charging has stopped, if necessary. Next, the control unit 8 performs a discharge process at a predetermined current value (C rate) for a predetermined time (step S302). At this time, the user may be notified of this, if necessary. When implementing such control at the time of electrodeposition detection, by setting the conditions for the discharge process (current value (C rate) and time) appropriately in advance, the charge of metallic lithium can be controlled in the subsequent charge/discharge process. This can prevent problems such as internal short circuits caused by analysis.

After starting the discharging process in step S302, the control unit 8 controls the AC impedance measured by the impedance measuring unit in the same way as the control for determining whether or not electrodeposition occurs during the charging process described above (steps S201 to S204). Based on the capacity (electric double layer) component of the negative electrode calculated from , it is determined whether or not the metallic lithium dendrites generated by electrodeposition in the negative electrode active material layer of the secondary battery 2 have been dissolved.

Specifically, in the subroutine shown in FIG. 11, the control unit 8 first obtains the measurement result of the AC impedance measured by the impedance measurement unit 7 as the output of the impedance measurement unit 7. At this time, the control unit 8 uses a low-pass filter (LPF) or the like to remove noise caused by high frequency components in the output from the impedance measurement unit 7 (S303).

Next, the value of the capacity (electric double layer) component of the negative electrode of the secondary battery 2 is calculated based on the output from the impedance measuring section 7 from which noise has been removed in step S303 (S304).

Subsequently, the control unit 8 compares the value of the capacity (electric double layer) component of the negative electrode of the secondary battery 2 calculated in step S304 with the measured value obtained by the previous measurement. Specifically, the slope (decrease rate per unit time) of the value of the capacity (electric double layer) component of the negative electrode is calculated (S305). Note that the amount of decrease in the value of the capacitance (electric double layer) component of the negative electrode calculated at predetermined intervals may be calculated.

Then, the control unit 8 determines whether the slope (decrease rate per unit time) of the value of the capacitance (electric double layer) component of the negative electrode, calculated as described above, is equal to or higher than a predetermined threshold value. It is determined whether or not (S306). In step S305, when the amount of decrease in the value of the capacitance (electric double layer) component of the negative electrode calculated at predetermined intervals is calculated, it is determined whether the amount of decrease is equal to or greater than a predetermined threshold value. to decide. In this way, by setting an appropriate threshold for the amount or rate of decrease in the value of the capacity (electric double layer) component of the negative electrode, it is possible to accurately determine whether or not metallic lithium dendrites are dissolving at this point. be able to. Here, as described above, the value (C _dl ) of the capacitance (electric double layer) component of the negative electrode increases as the surface area of the negative electrode increases. When the metallic lithium dendrites that were in contact with the electrodeposition growth inhibiting layer are dissolved by the above-mentioned discharge treatment, electrical conduction between the negative electrode active material layer and the depositing growth inhibiting layer via the metallic lithium dendrites is interrupted. be done. This can be regarded as an apparent sudden decrease in the surface area of the negative electrode, and is reflected in the AC impedance measurement results as a decrease in the value of the negative electrode's capacitance (electric double layer) component. . In this control, the presence or absence of dissolution of metallic lithium dendrites is determined using the decrease in the capacity (electric double layer) component of the negative electrode as an index. That is, in this embodiment, it can be said that the electrodeposition growth inhibiting layer also has a function as a detection section (sensor) for detecting dissolution of dendrites. By detecting the dissolution of this dendrite, it becomes possible to perform further charging processing on the secondary battery 2, so that the potential capacity of the secondary battery 2 can be fully utilized. becomes possible.

Here, if it is determined in step S306 that the slope (decrease rate per unit time) of the value of the capacity (electric double layer) component of the negative electrode of the secondary battery 2 is less than the threshold value (S306: NO) , at that point, it is determined that no dissolution of metallic lithium dendrites has occurred.

On the other hand, if it is determined in step S306 that the slope (decrease rate per unit time) of the value of the capacity (electric double layer) component of the negative electrode of the secondary battery 2 is equal to or higher than the threshold value (S306: YES), At that point, it is determined that dissolution of the metallic lithium dendrite has occurred.

Referring to the flowchart shown in FIG. 11, if it is determined in step S306 that the dissolution of metallic lithium dendrites has not occurred, the control unit 8 restarts the process from step S304. On the other hand, if it is determined in step S306 that electrodeposition has occurred, the control unit 8 starts the charging process (S307) at a charging current or C rate smaller than the charging process (step S102). In conjunction with this, the control unit 8 restarts the process from step S103. In this way, by restarting the charging process at a charging current or C rate lower than the previous charging process, charging can be performed in a state where the risk of electrodeposition occurring in the negative electrode active material layer of the secondary battery 2 is reduced. It becomes possible to continue processing.

In the above, the process of changing the conditions of the charging process has been described as an example of control at the time of electrodeposition detection. Alternatively, the restraining pressure applied in the stacking direction of the secondary battery 2 may be increased.

The control according to the present invention has been described in detail above, but the embodiment described with reference to the drawings is merely an example, and the present invention may be practiced by making appropriate modifications within the scope of the technical concept of the invention described in the claims.

In addition, according to another aspect of the present invention, a secondary battery charging method for charging the above-described secondary battery 2 is also provided. A method for charging a secondary battery is that when charging the secondary battery using a charging power source (external power source 9) capable of supplying power for charging the secondary battery 2, an alternating current of the secondary battery is charged. By measuring the impedance and based on the capacity (electric double layer) component of the negative electrode calculated from the measured AC impedance, it is determined whether metal lithium is electrodeposited in the negative electrode active material layer of the secondary battery. This includes the following:

1 All-solid-state lithium ion secondary battery system,
2 All-solid-state lithium ion secondary battery,
3 voltage sensor,
4 temperature sensor,
5 voltage and current adjustment section,
6 current sensor,
7 Impedance measurement section,
8 control unit,
9 External power supply,
10 Stacked battery,
11 positive electrode current collector,
12 negative electrode current collector,
13 positive electrode active material layer,
15 negative electrode active material layer,
17 solid electrolyte layer,
17a first sub-solid electrolyte layer,
17b electrodeposition growth inhibition layer,
17c second sub-solid electrolyte layer,
19 cell layer,
21 Power generation element,
25 positive electrode current collector plate,
27 negative electrode current collector plate,
29 Laminating film,
81 CPU,
82 Memory section.

Claims (18)

a positive electrode in which a positive electrode active material layer containing a positive electrode active material capable of intercalating and deintercalating lithium ions is disposed on the surface of a positive electrode current collector;
a negative electrode in which a negative electrode active material layer containing a negative electrode active material capable of intercalating and deintercalating lithium ions is disposed on the surface of a negative electrode current collector;
a solid electrolyte layer interposed between the positive electrode active material layer and the negative electrode active material layer and containing a solid electrolyte;
Equipped with a power generation element having
An all-solid lithium ion secondary battery in which the solid electrolyte layer has an electrodeposition growth inhibiting layer containing a solid material having a higher electrode potential than metal lithium, located between the sub-solid electrolyte layers (however, an all-solid lithium ion secondary battery including A porous sheet-like support member containing pores is embedded in the solid electrolyte layer, and at least a portion of the surface of the support member is covered with a metal salt derived from a metal having a lower ionization tendency than lithium and/or its metal ions. (except those coated). The all-solid-state lithium ion secondary battery according to claim 1, wherein the electrodeposition growth inhibiting layer is a layer containing the solid material and the solid electrolyte. The all-solid lithium ion diode according to claim 1 or 2, wherein the solid electrolyte layer is composed of the electrodeposition growth inhibiting layer and a pair of sub-solid electrolyte layers sandwiching the electrodeposition growth inhibiting layer. Next battery. At least a part of the outer periphery of the electrodeposition growth inhibiting layer is configured to protrude toward the negative electrode active material layer to cover the outer periphery of the sub-solid electrolyte layer located on the negative electrode active material layer side. The all-solid-state lithium ion secondary battery according to claim 3, wherein the all-solid-state lithium ion secondary battery is The all-solid lithium ion secondary battery according to claim 1, wherein the solid material is a conductive material. The all-solid-state lithium ion secondary battery according to claim 5, wherein the electrodeposition growth inhibiting layer includes a structure in which the solid material is three-dimensionally connected. The all-solid-state lithium ion secondary battery according to claim 6,
an impedance measurement unit that measures AC impedance of the all-solid-state lithium ion secondary battery;
Based on the capacity (electric double layer) component of the negative electrode calculated from the AC impedance measured by the impedance measuring section, it is determined whether or not metal lithium is deposited in the negative electrode active material layer. a control unit;
An all-solid-state lithium-ion secondary battery system. The control unit performs the determination when performing charging processing on the all-solid-state lithium ion secondary battery,
At this time, when the control unit determines that metal lithium electrodeposition has occurred in the negative electrode active material layer, it changes the conditions of the charging process so that the electrodeposition is less likely to occur. The all-solid-state lithium ion secondary battery system described in . The all-solid-state lithium ion secondary battery system according to claim 8, wherein the control unit stops charging when determining that metal lithium electrodeposition has occurred in the negative electrode active material layer. The control unit, when determining that metal lithium electrodeposition has occurred in the negative electrode active material layer, stops charging and then performs a discharging process on the all-solid-state lithium ion secondary battery. 9. The all-solid-state lithium ion secondary battery system according to 9. When performing the discharge treatment, the control unit is configured to control the amount of electricity generated by electrodeposition in the negative electrode active material layer based on the capacity (electric double layer) component of the negative electrode calculated from the AC impedance measured by the impedance measurement unit. The all-solid-state lithium ion secondary battery system according to claim 10, wherein a determination is made as to whether or not dendrites of metallic lithium that had been dissolved have been dissolved. When the control unit determines that metallic lithium dendrites generated by electrodeposition in the negative electrode active material layer have been dissolved, the control unit stops discharging, and then controls the all-solid-state lithium ion secondary battery to The all-solid-state lithium ion secondary battery system according to claim 11, wherein the charging process is performed at a charging current or a C rate that is smaller than the charging current during the charging process. a positive electrode in which a positive electrode active material layer containing a positive electrode active material capable of intercalating and deintercalating lithium ions is disposed on the surface of a positive electrode current collector;
a negative electrode in which a negative electrode active material layer containing a negative electrode active material capable of intercalating and deintercalating lithium ions is disposed on the surface of a negative electrode current collector;
a solid electrolyte layer interposed between the positive electrode active material layer and the negative electrode active material layer and containing a solid electrolyte;
Equipped with a power generation element having
The solid electrolyte layer has an electrodeposition growth inhibiting layer containing a solid material having a higher electrode potential than metallic lithium, located between the sub-solid electrolyte layers,
The solid material is a conductive material,
The electrodeposition growth inhibiting layer is an all-solid-state lithium ion secondary battery including a structure in which the solid material is three-dimensionally connected (provided that a porous sheet-like support member containing a plurality of pores is connected to the solid electrolyte layer). lithium, wherein at least a portion of the surface of the support member is coated with a metal salt and/or metal ions thereof derived from a metal embedded in the support member and having a lower ionization tendency than lithium, the method comprising:
When performing charging processing on the all-solid-state lithium-ion secondary battery using a charging power source capable of supplying power for charging the all-solid-state lithium-ion secondary battery, the AC impedance of the all-solid-state lithium-ion secondary battery to measure and
Determining whether or not metal lithium is electrodeposited in the negative electrode active material layer based on the capacity (electric double layer) component of the negative electrode calculated from the measured AC impedance;
A method for charging an all- solid-state lithium-ion secondary battery, including: Powder forming a solid electrolyte material to produce a sheet-like first sub-solid electrolyte layer;
A sheet-like electrodeposition growth inhibiting layer is produced by compacting a solid material having a higher electrode potential than the solid electrolyte material and metallic lithium on the exposed surface of at least one of the first sub-solid electrolyte layers. and,
Pressing a solid electrolyte material onto the exposed surface of the electrodeposition growth inhibiting layer to produce a sheet-like second sub-solid electrolyte layer;
A method for producing a solid electrolyte layer for an all-solid lithium ion secondary battery, comprising: Powder forming a solid electrolyte material to produce a sheet-like first sub-solid electrolyte layer;
Preliminarily compacting a solid material having a higher electrode potential than the solid electrolyte material and metallic lithium on the exposed surface of at least one of the first sub-solid electrolyte layers to produce a precursor for the electrodeposition growth inhibiting layer. and,
A portion of the precursor excluding at least a portion of the outer periphery is subjected to powder compaction to produce an electrodeposition growth inhibiting layer having a recessed portion surrounded by at least a portion of the outer periphery;
A solid electrolyte material is compacted into the recessed portion of the electrodeposition growth suppression layer to produce a second sub-solid electrolyte layer whose outer periphery is covered with at least a portion of the outer peripheral edge of the electrodeposition growth suppression layer. And,
A method for producing a solid electrolyte layer for an all-solid lithium ion secondary battery, comprising: The method for manufacturing a solid electrolyte layer for an all-solid-state lithium ion secondary battery according to claim 14 or 15, wherein the solid material is a conductive material. 17. The method for manufacturing a solid electrolyte layer for an all-solid-state lithium ion secondary battery according to claim 16, wherein the electrodeposition growth inhibiting layer includes a structure in which the solid material is three-dimensionally connected. a positive electrode in which a positive electrode active material layer containing a positive electrode active material capable of intercalating and deintercalating lithium ions is disposed on the surface of a positive electrode current collector;
a negative electrode in which a negative electrode active material layer containing a negative electrode active material capable of intercalating and deintercalating lithium ions is disposed on the surface of a negative electrode current collector;
a solid electrolyte layer interposed between the positive electrode active material layer and the negative electrode active material layer and containing a solid electrolyte;
A method for manufacturing an all-solid-state lithium ion secondary battery comprising a power generation element having the following steps:
A method for manufacturing an all-solid lithium ion secondary battery, comprising manufacturing the solid electrolyte layer by the manufacturing method according to any one of claims 14 to 17.