Secondary battery

Abstract

To provide means capable of preventing the electrodeposition of lithium at the end of a battery and the resulting growth of dendrite and the occurrence of an internal short circuit of the battery in a secondary battery provided with a lithium-containing negative electrode and a solid electrolyte layer.SOLUTION: In a secondary battery including a power generation element including a positive electrode, a negative electrode containing a negative electrode active material layer containing a negative electrode active material containing metallic lithium or a lithium-containing alloy, and a solid electrolyte layer intervening between these electrodes and containing a solid electrolyte, in at least a part of the outer peripheral edge of the interface between the negative electrode active material layer and the solid electrolyte layer, a low reactivity region is provided in which the value of the ratio of the lithium ion partial molar volume of the solid electrolyte layer to the lithium partial molar volume of the negative electrode active material layer is larger than the inside of the outer peripheral edge at the interface.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a secondary battery.

Background Art

[0002] In recent years, in order to address global warming, reduction of carbon dioxide emissions has been urgently desired. In the automotive industry, expectations are focused on reducing carbon dioxide emissions by introducing electric vehicles (EVs) and hybrid electric vehicles (HEVs), and development of non-aqueous electrolyte secondary batteries such as secondary batteries for motor drive, which hold the key to their practical use, has been actively carried out.

[0003] As a secondary battery for motor drive, it is required to have extremely high output characteristics and high energy compared with consumer lithium-ion secondary batteries used in mobile phones, notebook computers, etc. Therefore, lithium-ion secondary batteries having the highest theoretical energy among all realistic batteries have attracted attention and are currently being rapidly developed.

[0004] Here, currently widely used lithium-ion secondary batteries use a flammable organic electrolyte as the electrolyte. In such liquid-based lithium-ion secondary batteries, safety measures against liquid leakage, short circuit, overcharging, etc. are more strictly required than for other batteries.

[0005] Therefore, in recent years, research and development on all-solid-state batteries such as all-solid-state lithium-ion secondary batteries using oxide-based or sulfide-based solid electrolytes as the electrolyte have been actively carried out. A solid electrolyte is a material mainly composed of an ion conductor capable of ion conduction in a solid. For this reason, in all-solid-state lithium-ion secondary batteries, various problems caused by a flammable organic electrolyte as in conventional liquid-based lithium-ion secondary batteries do not occur in principle. Also, generally, when using a high-potential and large-capacity positive electrode material and a large-capacity negative electrode material, a significant improvement in the output density and energy density of the battery can be achieved. All-solid-state lithium-ion secondary batteries using sulfur monomer (S) or sulfide-based materials as the positive electrode active material are promising candidates.

[0006] Incidentally, in a lithium-ion secondary battery, the negative electrode potential decreases as charging progresses. When the negative electrode potential decreases below 0 V (vs. Li / Li+), metallic lithium is deposited on the negative electrode and dendrite (branched) crystals are deposited (this phenomenon is also referred to as the electrodeposition of metallic lithium). In particular, in an all-solid-state battery using metallic lithium or a lithium-containing alloy as a negative electrode active material, the electrodeposition of metallic lithium is the charging reaction itself. Here, when the electrodeposition of metallic lithium occurs excessively in an all-solid-state battery and the deposited dendrites reach the positive electrode active material layer, an internal short circuit of the battery may be caused. Such electrodeposition of metallic lithium is likely to occur at the end (edge portion) of the battery, and a short circuit due to the growth of dendrites is also likely to occur along the side surface of the end of the battery.

[0007] For the purpose of preventing such electrodeposition of metallic lithium and the resulting internal short circuit of the battery in an all-solid-state battery, for example, Patent Document 1 discloses a technique of making the negative electrode slightly smaller than the outer circumference of the solid electrolyte layer to cut off the supply of electrons to the negative electrode and prevent the occurrence of electrodeposition of metallic lithium at the end of the battery.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, there is still room for improvement even with the technique described in Patent Document 1.

[0010] Therefore, an object of the present invention is to provide a means capable of preventing the electrodeposition of lithium, the growth of dendrites resulting therefrom, and the occurrence of an internal short circuit of the battery at the end of the battery in a secondary battery including a lithium-containing negative electrode and a solid electrolyte layer.

Means for Solving the Problem

[0011] The inventors of the present invention conducted intensive studies to solve the above problems. As a result, in a secondary battery including metallic lithium or a lithium-containing alloy as a negative electrode active material and having a solid electrolyte layer, at least a part of the outer peripheral edge of the interface between the negative electrode active material layer and the solid electrolyte layer has a lower reactivity region where the value of the ratio of the lithium ion partial molar volume of the solid electrolyte layer to the lithium partial molar volume of the negative electrode active material layer is larger compared to the inside of the outer peripheral edge at the above interface. The inventors found that the above problems can be solved by providing such a region, and thus completed the present invention.

[0012] That is, according to one aspect of the present invention, there is provided a secondary battery including a positive electrode in which a positive electrode active material layer containing a positive electrode active material 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 including metallic lithium or a lithium-containing alloy is disposed on the surface of a negative electrode current collector, and a power generation element having a solid electrolyte layer containing a solid electrolyte interposed between the positive electrode active material layer and the negative electrode active material layer. In the secondary battery, at least a part of the outer peripheral edge of the interface between the negative electrode active material layer and the solid electrolyte layer has a lower reactivity region where the value of the ratio of the lithium ion partial molar volume of the solid electrolyte layer to the lithium partial molar volume of the negative electrode active material layer is larger compared to the inside of the outer peripheral edge at the above interface.

Advantages of the Invention

[0013] In the secondary battery according to the present invention, the reactivity of lithium at the interface corresponding to the lower reactivity region of the outer peripheral edge is lower compared to the inside of the outer peripheral edge. Therefore, according to the present invention, in a secondary battery including a lithium-containing negative electrode and a solid electrolyte layer, it is possible to effectively prevent the deposition of lithium at the end of the battery, the growth of dendrites caused thereby, and the occurrence of an internal short circuit of the battery.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

MODE FOR CARRYING OUT THE INVENTION

[0015] One embodiment of the present invention includes a positive electrode in which a positive electrode active material layer containing a positive electrode active material is disposed on the surface of a positive electrode current collector, and a negative electrode in which a negative electrode active material layer containing a negative electrode active material including metallic lithium or a lithium-containing alloy is disposed on the surface of a negative electrode current collector, and a solid electrolyte layer including a solid electrolyte interposed between the positive electrode active material layer and the negative electrode active material layer. A secondary battery, in which at least a part of the outer peripheral edge of the interface between the negative electrode active material layer and the solid electrolyte layer has a low reactivity region where the value of the ratio of the lithium ion partial molar volume of the solid electrolyte layer to the lithium partial molar volume of the negative electrode active material layer is larger than that inside the outer peripheral edge at the interface.

[0016] Hereinafter, embodiments of the above-described embodiment will be described with reference to the drawings. However, the technical scope of the present invention should be determined based on the description in the claims and is not limited only to the following embodiments. Note that the dimensional ratios in the drawings are exaggerated for convenience of explanation and may be different from the actual ratios.

[0017] FIG. 1 is a perspective view showing the appearance of a flat laminated all-solid-state battery which is an embodiment of a secondary battery according to the present invention. FIG. 2 is a cross-sectional view taken along line 2-2 shown in FIG. 1. By making it a laminated type, the battery can be made compact and have a high capacity. In this specification, a flat laminated non-bipolar all-solid-state lithium-ion secondary battery (hereinafter, also simply referred to as "laminated battery") shown in FIGS. 1 and 2 will be taken as an example and described in detail. However, when viewed from the electrical connection form (electrode structure) inside the all-solid-state battery according to this embodiment, it can be applied to both non-bipolar (internal parallel connection type) batteries and bipolar (internal series connection type) batteries.

[0018] As shown in FIG. 2, the laminated battery 10 has a rectangular flat shape, and a positive electrode current collector plate 25 and a negative electrode current collector plate 27 for extracting electric power are drawn out from both side portions thereof. The power generation element 21 is wrapped by a battery exterior material (laminate film 29) of the laminated battery 10, and the periphery thereof is heat-sealed. The power generation element 21 is sealed in a state where the positive electrode current collector plate 25 and the negative electrode current collector plate 27 are drawn out to the outside.

[0019] Note that the all-solid-state battery according to this embodiment is not limited to a flat laminated shape. In the case of a wound all-solid-state battery, it may have a cylindrical shape, or it may be a deformed cylindrical shape such as a rectangular flat shape, and is not particularly limited. In the case of the above cylindrical shape, a laminate film may be used for its exterior material, or a conventional cylindrical can (metal can) may be used, and is not particularly limited. Preferably, the power generation element is housed inside a laminate film containing aluminum. By this form, weight reduction can be achieved.

[0020] Regarding the extraction of the current collectors (25, 27) shown in FIG. 1, there are no particular restrictions either. The positive electrode current collector 25 and the negative electrode current collector 27 may be drawn out from the same side, or the positive electrode current collector 25 and the negative electrode current collector 27 may be divided into a plurality of each and drawn out from each side, etc., and it is not limited to those shown in FIGS. 1 and 2. Further, in a wound lithium ion battery, for example, a cylindrical can (metal can) may be used to form terminals instead of tabs.

[0021] As shown in FIG. 2, the laminated battery 10 of the present embodiment has a structure in which a flat substantially rectangular power generation element 21 in which a charge and discharge reaction actually proceeds is sealed inside a laminate film 29 which is a battery exterior material. Here, the power generation element 21 has a configuration in which a positive electrode, a solid electrolyte layer 17, and a negative electrode are laminated. In the present embodiment, the solid electrolyte layer 17 contains LGPS (Li 10 GeP2S 12 ) which is one kind of sulfide solid electrolyte. The positive electrode has a structure in which positive electrode active material layers 13 containing a positive electrode active material are disposed on both surfaces 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 (here, metallic lithium) are disposed on both surfaces 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 interposed therebetween, and the positive electrode, the solid electrolyte layer, and the negative electrode are laminated in this order. Thereby, the adjacent positive electrode, solid electrolyte layer, and negative electrode constitute one single battery layer 19. Therefore, it can be said that the laminated battery 10 shown in FIG. 2 has a configuration in which a plurality of single battery layers 19 are laminated and electrically connected in parallel.

[0022] As shown in FIG. 2, in the outermost positive electrode current collectors located on both outermost layers of the power generation element 21, the positive electrode active material layers 13 are disposed only on one side, but active material layers may be provided on both sides. That is, instead of using a current collector dedicated to the outermost layer with an active material layer provided only on one side, a current collector having active material layers on both sides may be used as the outermost layer current collector as it is.

[0023] The positive current collector 11 and the negative current collector 12 are each provided with a positive current collector plate (tab) 25 and a negative current collector plate (tab) 27 that are electrically connected to the respective electrodes (positive electrode and negative electrode), and are structured to be led out to the outside of the laminate film 29 so as to be sandwiched between the ends of the laminate film 29 which is the battery exterior material. The positive current collector plate 25 and the negative current collector plate 27 may each be attached to the positive current collector 11 and the negative current collector 12 of the respective electrodes by ultrasonic welding, resistance welding, etc. via positive and negative leads (not shown) as necessary.

[0024] Figure 3 is an enlarged cross-sectional view of a single cell layer 19 that constitutes the power generation element 21 of the laminated battery 10 shown in FIGS. 1 and 2.

[0025] In the present embodiment, as shown in FIG. 3, over the entire circumference of the outer peripheral edge portion P of the interface between the negative electrode active material layer 15 and the solid electrolyte layer 17, in the region of the negative electrode active material layer 15 on the solid electrolyte layer 17 side corresponding to the outer peripheral edge portion P, a region 15a is provided where the partial molar volume of lithium is smaller than that in the region corresponding to the inside of the outer peripheral edge portion P of the negative electrode active material layer 15. Specifically, this region 15a is formed by arranging gold instead of metallic lithium.

[0026] Also, in the present embodiment shown in FIG. 3, over the entire circumference of the outer peripheral edge portion P of the interface between the negative electrode active material layer 15 and the solid electrolyte layer 17, in the region of the solid electrolyte layer 17 on the negative electrode active material layer 15 side corresponding to the outer peripheral edge portion P, a region 17a is provided where the partial molar volume of lithium ions is larger than that in the region corresponding to the inside of the outer peripheral edge portion P of the solid electrolyte layer 17. Specifically, this region 17a is formed by arranging a mixture of an oxymethylene bond PEG400 and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) instead of LGPS.

[0027] Thus, in the embodiment shown in FIG. 3, the region 15a in the negative electrode active material layer 15 and the region 17a in the solid electrolyte layer 17 are configured to be adjacent to each other over the entire outer peripheral edge P of the interface between the negative electrode active material layer 15 and the solid electrolyte layer 17. As a result, in the embodiment shown in FIG. 3, over the entire outer peripheral edge P of the interface between the negative electrode active material layer 15 and the solid electrolyte layer 17, there exists a region where the value of the ratio of the lithium ion partial molar volume of the solid electrolyte layer 17 to the lithium partial molar volume of the negative electrode active material layer 15 is larger as compared with the inside of the outer peripheral edge P of the interface. In such a region existing at the outer peripheral edge P of the interface, the reactivity of lithium at the interface is lower as compared with the inside of the outer peripheral edge P. Therefore, in this specification, such a region is referred to as a "low reactivity region". Due to the relationship of the reactivity of lithium at such an interface, according to the present invention, in a secondary battery including a lithium-containing negative electrode and a solid electrolyte layer, it is possible to effectively prevent the electrodeposition of lithium at the end of the battery, the growth of dendrites caused thereby, and the occurrence of an internal short circuit of the battery. The mechanism by which such an effect is achieved will be described below.

[0028] Referring to the literature (C. Monroe, J. Newman, Journal of The Electrochemical Society, 152 (2) A396 - A404 (2005)), the electrochemical reaction formula thermodynamically interpreted for a secondary battery including a lithium-containing negative electrode is represented as in the following Equation 1.

[0029]

Equation

[0030] In Equation 1, i BV represents the reactivity of lithium at the interface, and Δμ e-represents the electrochemical potential of lithium at the interface. As is clear from Equation 1, the reactivity of lithium at the interface is positively correlated with the electrochemical potential of lithium at the interface. Here, the electrochemical potential Δμ of lithium at the interface e- is expressed as in Equation 2 below.

[0031]

Equation

[0032] Therefore, according to Equation 2, in a region where the value of the ratio of the partial molar volume of lithium ions in the solid electrolyte layer 17 to the partial molar volume of lithium in the negative electrode active material layer 15 is larger compared to the inside of the outer peripheral edge at the interface, the electrochemical potential Δμ of lithium at the interface e- has a smaller value compared to the inside of the outer peripheral edge. In other words, it can be said that this region is a region where the reactivity (i BV ) of lithium at the interface is lower (i.e., a low reactivity region). In the present invention, in a secondary battery including a lithium-containing negative electrode and a solid electrolyte layer, the presence of such a low reactivity region at the end (outer peripheral edge) of the battery can effectively prevent the deposition of lithium at the end (outer peripheral edge), the growth of dendrites caused thereby, and the occurrence of internal short circuit of the battery.

[0033] Note that the value of the partial molar volume of lithium in the negative electrode active material layer 15 and the value of the partial molar volume of lithium ions in the solid electrolyte layer 17 can be measured by appropriately referring to conventionally known knowledge. For example, in the literature (Koerver, R. et al., Chemo-Mechanical Expansion of Lithium Electrode Materials - On the Route to Mechanically Optimized All-Solid-State Batteries. Energy Environ. Sci. 2018, 11, 2142 - 2158), a detailed discussion on the partial molar volume of lithium is made.

[0034] In the embodiment shown in FIG. 3, the low-reactivity region is configured to exist over the entire outer peripheral edge portions of the negative electrode active material layer 15 and the solid electrolyte layer 17, but is not limited to such a form. For example, even in a form in which the low-reactivity region exists only in a part of the outer peripheral edge portion, as long as the region satisfies the definition of the low-reactivity region described above, it is included in the technical scope of the present invention. In the embodiment shown in FIG. 3, the outer peripheral edge portion P is provided so as to include the end portions of the negative electrode active material layer 15 and the solid electrolyte layer 17, but may be provided slightly inside the end portions in some cases. However, from the viewpoint of effectively preventing the electrodeposition of metallic lithium at the end portions and the growth of dendrites and the occurrence of internal short circuit of the battery due thereto, the outer peripheral edge portion P is provided so as to include the end portions of the negative electrode active material layer 15 and the solid electrolyte layer 17. Further, the width at which the outer peripheral edge portion P is provided as viewed from the end portions of the negative electrode active material layer 15 and the solid electrolyte layer 17 (the length of the outer peripheral edge portion P shown in FIG. 3) is not particularly limited, and may be provided at a width at which the operational effects of the present invention can be obtained. As an example, the width at which the outer peripheral edge portion P is provided (the length of the outer peripheral edge portion P shown in FIG. 3) is preferably 1 mm to 5 cm, more preferably 3 mm to 3 cm, and still more preferably 5 mm to 2 cm.

[0035] Also, in the embodiment shown in FIG. 3, in both the negative electrode active material layer 15 and the solid electrolyte layer 17, the lithium ion partial molar volume and the lithium partial molar volume of the outer peripheral edge portion are controlled so as to constitute the low-reactivity region, respectively, but are not limited to such a form. For example, as shown in FIGS. 4 and 5, a form in which only one of these is controlled may be used.

[0036] FIG. 4 is an enlarged cross-sectional view showing a modified example of the single cell layer shown in FIG. 3. Further, FIG. 5 is an enlarged cross-sectional view showing another modified example of the single cell layer shown in FIG. 3.

[0037] In the embodiment shown in FIG. 4, similar to the embodiment shown in FIG. 3, over the entire outer peripheral edge of the interface between the negative electrode active material layer 15 and the solid electrolyte layer 17, in the region of the negative electrode active material layer 15 on the solid electrolyte layer 17 side corresponding to the outer peripheral edge, a region 15a is provided where the lithium partial molar volume is smaller than in the region corresponding to the inside of the outer peripheral edge of the negative electrode active material layer 15. On the other hand, with respect to the outer peripheral edge of the solid electrolyte layer 17, no control is particularly performed to change the lithium ion partial molar volume. That is, in the embodiment shown in FIG. 4, the constituent material of the negative electrode active material layer 15 is the same in the region corresponding to the outer peripheral edge and the region corresponding to the inside of the outer peripheral edge. It can be said that in the embodiment shown in FIG. 4 having such a configuration, there is a low reactivity region similar to the embodiment shown in FIG. 3. In the embodiment shown in FIG. 3, the region 15a is formed by arranging gold instead of metallic lithium, but the lithium partial molar volume of the negative electrode active material layer 15 corresponding to the outer peripheral edge may be controlled by other methods. For example, if the lithium concentration in the region 15a decreases, it is possible to provide the region 15a using a metal other than gold. Also, the region 15a may be provided by arranging materials having the same composition except for different lithium contents.

[0038] Also, in the embodiment shown in FIG. 5, similar to the embodiment shown in FIG. 3, over the entire outer peripheral edge of the interface between the negative electrode active material layer 15 and the solid electrolyte layer 17, in the region of the solid electrolyte layer 17 on the negative electrode active material layer 15 side corresponding to the outer peripheral edge, a region 17a is provided where the partial molar volume of lithium ions is larger than that in the region corresponding to the inside of the outer peripheral edge of the solid electrolyte layer 17. On the other hand, with respect to the outer peripheral edge of the negative electrode active material layer 15, no control is particularly performed to change the partial molar volume of lithium. That is, in the embodiment shown in FIG. 5, the constituent material of the negative electrode active material layer 15 is the same in the region corresponding to the outer peripheral edge and the region corresponding to the inside of the outer peripheral edge. Even in the embodiment shown in FIG. 5 having such a configuration, it can be said that there is a low reactivity region similar to the embodiment shown in FIG. 3. In the embodiment shown in FIG. 3, the region 17a is formed by disposing a mixture of an oxymethylene bond PEG400 and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) instead of LGPS, but the partial molar volume of lithium ions in the solid electrolyte layer 17 corresponding to the outer peripheral edge may be controlled by other methods. For example, if the lithium ion concentration in the region 17a decreases, it is possible to provide the region 17a using lithium salts and diluents other than the materials described above.

[0039] Hereinafter, the main constituent members of the secondary battery according to this embodiment will be described.

[0040] [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 limitation on the material constituting the current collector. As the constituent material of the current collector, for example, metals and conductive resins can be adopted.

[0041] Specifically, examples of the metal include aluminum, nickel, iron, stainless steel, titanium, copper, etc. In addition to these, a clad material of nickel and aluminum, a clad material of copper and aluminum, etc. may also be used. Further, a foil in which the metal surface is coated with aluminum may also be used. Among these, from the viewpoints of electron conductivity, battery operating potential, adhesion of the negative electrode active material to the current collector by sputtering, etc., aluminum, stainless steel, copper, and nickel are preferable.

[0042] In addition, examples of the resin having the latter conductivity include a resin in which a conductive filler is added to a non-conductive polymer material as necessary.

[0043] Examples of the non-conductive polymer material include polyethylene (PE; such as high-density polyethylene (HDPE) and low-density polyethylene (LDPE)), polypropylene (PP), polyethylene terephthalate (PET), polyether nitrile (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), etc. Such non-conductive polymer materials can have excellent potential resistance or solvent resistance.

[0044] A conductive filler can 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 a non-conductive polymer, a conductive filler is inevitably essential to impart conductivity to the resin.

[0045] The conductive filler can be used without particular limitation as long as it is a substance having conductivity. For example, metals and conductive carbon etc. can be mentioned as materials excellent in conductivity, potential resistance, or lithium ion blocking property. Although there is no particular limitation on the metal, it preferably contains at least one metal selected from the group consisting of Ni, Ti, Al, Cu, Pt, Fe, Cr, Sn, Zn, In, and Sb, or an alloy or metal oxide containing these metals. Also, there is no particular limitation on the conductive carbon. Preferably, it contains at least one selected from the group consisting of acetylene black, Vulcan (registered trademark), Black Pearl (registered trademark), carbon nanofiber, Ketjen black (registered trademark), carbon nanotube, carbon nanohorn, carbon nanoballon, and fullerene.

[0046] The addition amount of the conductive filler is not particularly limited as long as it can impart sufficient conductivity to the current collector, and generally it is 5 to 80% by mass based on 100% by mass of the total mass of the current collector.

[0047] Note that the current collector may have a single-layer structure composed of a single material, or may have a laminated structure in which layers made of these materials are appropriately combined. From the viewpoint of weight reduction of the current collector, it preferably contains a conductive resin layer made of at least a resin having conductivity. Also, from the viewpoint of blocking the movement of lithium ions between single battery layers, a metal layer may be provided on a part of the current collector.

[0048] [Negative electrode active material layer] The negative electrode active material layer contains a negative electrode active material. In the present invention, the negative electrode active material essentially contains metallic lithium alone (Li) or a lithium-containing alloy. The types of these negative electrode active materials are not particularly limited, but examples of the lithium-containing alloy include an alloy of lithium and at least one material that can be alloyed with lithium. Here, examples of the material that can be alloyed with lithium include Si, Au, In, Ge, Sn, Pb, Al, Zn, H, Ca, Sr, Ba, Ru, Rh, Ir, Pd, Pt, Ag, Cd, Hg, Ga, Tl, C, N, Sb, Bi, O, S, Se, Te, Cl, etc. Among these, from the viewpoint of being able to construct a battery excellent in capacity and energy density, the material that can be alloyed with lithium preferably contains at least one element selected from the group consisting of Si, Au, In, Ge, Sn, Pb, Al, and Zn, and more preferably contains Si, Au, or In. In some cases, two or more negative electrode active materials may be used in combination. Of course, as long as metallic lithium or a lithium-containing alloy is essentially contained, negative electrode active materials other than the above may be used.

[0049] Examples of the shape of the negative electrode active material include particulate (spherical, fibrous), thin film, etc., and a thin film shape is preferred. When the negative electrode active material has a particulate shape, its average particle diameter (D 50 ) is preferably in the range of, for example, 1 nm to 100 μm, more preferably in the range of 10 nm to 50 μm, still more preferably in the range of 100 nm to 20 μm, and particularly preferably in the range of 1 to 20 μm. In this specification, the value of the average particle diameter (D 50 ) of the active material can be measured by the laser diffraction scattering method.

[0050] The content of the negative electrode active material in the negative electrode active material layer is not particularly limited, but is preferably in the range of, for example, 40 to 100% by mass, and more preferably in the range of 50 to 100% by mass.

[0051] The negative electrode active material layer may further contain a solid electrolyte. By including a 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, with sulfide solid electrolytes being preferred.

[0052] Examples of the sulfide solid electrolyte include LiI-Li2S-SiS2, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li2S-P2S5, LiI-Li3PS4, LiI-LiBr-Li3PS 4、 Li3PS 4、 Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (where m and n are positive numbers, and Z is any one of Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li x MO y (where x and y are positive numbers, and M is any one of P, Si, Ge, B, Al, Ga, and In), etc. Note that the description of "Li2S-P2S5" means a sulfide solid electrolyte formed using a raw material composition containing Li2S and P2S5, and the same applies to other descriptions.

[0053] The sulfide solid electrolyte may, for example, have a Li3PS4 skeleton, a Li4P2S7 skeleton, or a Li4P2S6 skeleton. Examples of the sulfide solid electrolyte having a Li3PS4 skeleton include LiI-Li3PS4, LiI-LiBr-Li3PS 4、 Li3PS4. Also, examples of the sulfide solid electrolyte having a Li4P2S7 skeleton include a Li-P-S-based solid electrolyte called LPS (for example, Li7P3S 11) can be mentioned. Further, as the sulfide solid electrolyte, for example, LGPS represented by Li (4-x) Ge (1-x) P x S4 (where x satisfies 0 < x < 1) may be used. Among them, the sulfide solid electrolyte contained in the active material layer is preferably a sulfide solid electrolyte containing P element, and the sulfide solid electrolyte is more preferably a material mainly composed of Li2S - P2S5. Further, the sulfide solid electrolyte may contain halogen (F, Cl, Br, I). In a preferred embodiment, the sulfide solid electrolyte contains Li6PS5X (where X is Cl, Br or I, preferably Cl).

[0054] When the sulfide solid electrolyte is of the Li2S - P2S5 system, the ratio of Li2S and P2S5 is preferably in the range of Li2S:P2S5 = 50:50 to 100:0 in terms of molar ratio, and more preferably Li2S:P2S5 = 70:30 to 80:20.

[0055] The sulfide solid electrolyte may be a sulfide glass, a crystallized sulfide glass, or a crystalline material obtained by a solid phase method. The sulfide glass can be obtained, for example, by performing mechanical milling (such as a ball mill) on the raw material composition. The crystallized sulfide glass can be obtained, for example, by heat - treating the sulfide glass at a temperature above the crystallization temperature. The ionic conductivity (for example, Li ion conductivity) of the sulfide solid electrolyte at room temperature (25 °C) is preferably, for example, 1×10 -5 S / cm or more, and more preferably 1×10 -4 S / cm or more. The value of the ionic conductivity of the solid electrolyte can be measured by the alternating current impedance method.

[0056] Examples of the oxide solid electrolyte include compounds having a NASICON - type structure. As an example of a compound having a NASICON - type structure, the general formula Li 1+x Al x Ge 2-xCompounds represented by (PO4)3 (0 ≤ x ≤ 2) (LAGP), general formula Li 1+x Al x Ti 2-x (PO4)3 (0 ≤ x ≤ 2) (LATP), etc. Examples of other oxide solid electrolytes include LiLaTiO (e.g., Li 0.34 La 0.51 TiO3), LiPON (e.g., Li 2.9 PO 3.3 N 0.46 ), LiLaZrO (e.g., Li7La3Zr2O 12 ), etc.

[0057] Examples of the shape of the solid electrolyte include particle shapes such as true spherical and elliptical spherical shapes, and thin film shapes. When the solid electrolyte is in 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, and more preferably 0.1 μm or more.

[0058] The content of the solid electrolyte in the negative electrode active material layer is preferably in the range of 0 to 60% by mass, and more preferably in the range of 0 to 50% by mass.

[0059] In addition to the above-mentioned negative electrode active material and solid electrolyte, the negative electrode active material layer may further contain at least one of a conductive assistant and a binder.

[0060] Examples of the conductive aid include, but are not limited to, 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-based carbon fibers, pitch-based carbon fibers, rayon-based carbon fibers, activated carbon fibers, etc.), carbon nanotubes (CNT), and carbons such as carbon black (specifically, acetylene black, Ketjen black (registered trademark), furnace black, channel black, thermal lamp black, etc.). Further, those obtained by coating the above metal materials around particulate ceramic materials or resin materials by plating or the like can also be used as the conductive aid. Among these conductive aids, from the viewpoint of electrical stability, it is preferably included at least one selected from the group consisting of aluminum, stainless steel, silver, gold, copper, titanium, and carbon, more preferably included at least one selected from the group consisting of aluminum, stainless steel, silver, gold, and carbon, and even more preferably included at least one kind of carbon. These conductive aids may be used alone or in combination of two or more kinds.

[0061] The shape of the conductive aid is preferably particulate or fibrous. When the conductive aid is particulate, the shape of the particles is not particularly limited and may be any shape such as powdery, spherical, rod-shaped, needle-shaped, plate-shaped, columnar, irregular-shaped, flaky, spindle-shaped, etc.

[0062] When the conductive aid is particulate, the average particle diameter (primary particle diameter) is not particularly limited, but from the viewpoint of the electrical characteristics of the battery, it is preferably 0.01 to 10 μm. In this specification, the "particle diameter of the conductive aid" means the maximum distance L among the distances between any two points on the contour line of the conductive aid. As the value of the "average particle diameter of the conductive aid", the value calculated as the average value of the particle diameters of the particles observed in several to several tens of fields of view using observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM) shall be adopted.

[0063] When the negative electrode active material layer contains a conductive assistant, the content of the conductive assistant in the negative electrode active material layer is not particularly limited, but is preferably 0 to 10% by mass, more preferably 2 to 8% by mass, and still more preferably 4 to 7% by mass with respect to the total mass of the negative electrode active material layer. Within such a 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 the improvement of battery characteristics.

[0064] On the other hand, the binder is not particularly limited, and examples thereof include the following materials.

[0065] Thermoplastic polymers such as polybutylene terephthalate, polyethylene terephthalate, polyvinylidene fluoride (PVDF) (including compounds in which hydrogen atoms are substituted with other halogen elements), polyethylene, polypropylene, polymethylpentene, polybutene, polyether nitrile, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, ethylene-vinyl acetate copolymer, polyvinyl chloride, styrene-butadiene rubber (SBR), ethylene-propylene-diene copolymer, styrene-butadiene-styrene block copolymer and its hydrogenated product, styrene-isoprene-styrene block copolymer and its hydrogenated product, etc.; fluororesins such as tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polyvinyl fluoride (PVF), etc.; 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 (VDF-PFMVE-TFE-based fluororubber), vinylidene fluoride-chlorotrifluoroethylene-based fluororubber (VDF-CTFE-based fluororubber), etc., vinylidene fluoride-based fluororubbers; epoxy resins, etc. Among them, polyimide, styrene-butadiene rubber, carboxymethyl cellulose, polypropylene, polytetrafluoroethylene, polyacrylonitrile, and polyamide are more preferred.

[0066] The thickness of the negative electrode active material layer varies depending on the configuration of the intended all-solid-state battery. For example, it is preferably in the range of 0.1 to 1000 μm.

[0067] [Positive electrode active material layer] The positive electrode active material layer contains a positive electrode active material. The type of the positive electrode active material is not particularly limited, but elemental sulfur (S8) or a reduction product of sulfur containing lithium (any of the compounds of Li2S8 to Li2S) is preferably used. Here, for example, elemental sulfur (S8) has an extremely large theoretical capacity of about 1670 mAh / g and has the advantages of low cost and abundant resources. In this case, when the all-solid-state battery is provided in a charged state, it contains elemental sulfur (S8) as the positive electrode active material. Further, when the all-solid-state battery is provided in a discharged state, it contains a reduction product of sulfur containing lithium (any of the compounds of Li2S8 to Li2S described above) as the positive electrode active material.

[0068] Note that the positive electrode active material layer may contain a positive electrode active material other than the above-described elemental sulfur (S8) or a reduction product of sulfur containing lithium (any of the compounds of Li2S8 to Li2S described above). However, the ratio of the elemental sulfur or the reduction product of sulfur containing lithium in the positive electrode active material contained in the positive electrode active material layer is preferably 50 to 100% by mass, more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, even more preferably 95 to 100% by mass, particularly preferably 98 to 100% by mass, and most preferably 100% by mass.

[0069] Examples of cathode active materials other than sulfur monomers or reduced products of sulfur containing lithium include disulfide compounds, sulfur-modified polyacrylonitrile represented by the compounds described in WO 2010 / 044437 pamphlet, sulfur-modified polyisoprene, rubane acid (dithiooxamide), polysulfurized carbon, etc. Inorganic sulfur compounds such as S-carbon composite, TiS2, TiS3, TiS4, NiS, NiS2, CuS, FeS2, MoS2, MoS3 can also be used. Further, examples of cathode active materials containing no sulfur include layered rock salt type active materials such as LiCoO2, LiMnO2, LiNiO2, LiVO2, Li(Ni-Mn-Co)O2, spinel type active materials such as LiMn2O4, LiNi 0.5 Mn 1.5 O4 and other spinel type active materials, olivine type active materials such as LiFePO4, LiMnPO4, Si-containing active materials such as Li2FeSiO4, Li2MnSiO4, etc. Examples of oxide active materials other than the above include, for example, Li4Ti5O 12 and the like. In some cases, two or more cathode active materials may be used in combination. Of course, cathode active materials other than the above may be used.

[0070] Examples of the shape of the cathode active material include particulate (spherical, fibrous), thin film, etc. When the cathode active material is in particulate form, its average particle size (D 50 ) is preferably in the range of, for example, 1 nm to 100 μm, more preferably in the range of 10 nm to 50 μm, still more preferably in the range of 100 nm to 20 μm, and particularly preferably in the range of 1 to 20 μm. In this specification, the value of the average particle size (D 50 ) of the active material can be measured by the laser diffraction scattering method.

[0071] The content of the cathode active material in the cathode active material layer is not particularly limited, but is preferably in the range of, for example, 40 to 99% by mass, and more preferably in the range of 50 to 90% by mass.

[0072] The positive electrode active material layer may also further contain a conductive aid and / or a binder, similar to the negative electrode active material layer.

[0073] [Solid electrolyte layer] The solid electrolyte layer of the all-solid-state battery according to this embodiment contains a solid electrolyte as a main component and is a layer interposed between the above-described positive electrode active material layer and negative electrode active material layer. Further, from the viewpoint of excellent ionic conductivity and durability, the solid electrolyte layer of the all-solid-state battery according to this embodiment preferably contains a sulfide solid electrolyte as an essential component, and in this case, other solid electrolytes may also be contained. However, the proportion of the sulfide solid electrolyte in the solid electrolyte contained in the solid electrolyte layer is preferably 50 to 100% by mass, more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, even more preferably 95 to 100% by mass, particularly preferably 98 to 100% by mass, and most preferably 100% by mass. Note that since the specific forms of the sulfide solid electrolyte and other solid electrolytes contained in the solid electrolyte layer are the same as those described above, detailed description thereof is omitted here.

[0074] The content of the solid electrolyte in the solid electrolyte layer is preferably in the range of, for example, 10 to 100% by mass, more preferably in the range of 50 to 100% by mass, and still more preferably in the range of 90 to 100% by mass.

[0075] In addition to the above-described solid electrolyte, the solid electrolyte layer may further contain a binder. Since the specific forms of the binder that can be contained in the solid electrolyte layer are the same as those described above, detailed description thereof is omitted here.

[0076] The thickness of the solid electrolyte layer varies depending on the configuration of the target all-solid-state battery, but is preferably in the range of, for example, 1 to 1000 μm, and more preferably in the range of 10 to 300 μm.

[0077] [Positive electrode current collector and negative electrode current collector] The material constituting the current collectors (25, 27) is not particularly limited, and known highly conductive materials conventionally used as current collectors for secondary batteries can be used. As the constituent material of the current collector, 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 preferable, and aluminum is particularly preferable. Note that the same material may be used for the positive electrode current collector 25 and the negative electrode current collector 27, or different materials may be used.

[0078] [Positive electrode lead and negative electrode lead] Although not shown, the current collectors (11, 12) and the current collectors (25, 27) may be electrically connected via a positive electrode lead or a negative electrode lead. As the constituent material of the positive electrode and the negative electrode leads, materials used in known lithium-ion secondary batteries can be similarly adopted. Note that the portion taken out from the exterior is preferably coated with a heat shrinkable tube having heat insulation properties or the like so as not to come into contact with peripheral devices, wiring, etc. and cause leakage and affect the product (for example, automotive parts, particularly electronic devices, etc.).

[0079] [Battery exterior material] As the battery exterior material, a known metal can case can be used, and in addition, as shown in FIGS. 1 and 2, a bag-shaped case using a laminate film 29 containing aluminum that can cover the power generation element can be used. For the laminate film, for example, a laminate film having a three-layer structure formed by laminating PP, aluminum, and nylon in this order can be used, but it is not limited thereto. From the viewpoint of excellent high output and cooling performance and being suitably used for large-sized device batteries for EV and HEV, a laminate film is desirable. Further, since the external pressure applied to the power generation element can be easily adjusted, the exterior body is more preferably a laminate film containing aluminum.

[0080] The laminated battery according to the embodiment shown in FIG. 2 has a configuration in which a plurality of single battery layers are connected in parallel, and thus has a high capacity and excellent cycle durability. Therefore, the laminated battery according to the present embodiment is suitably used as a driving power source for EVs and HEVs.

[0081] As described above, one embodiment of the secondary battery has been described. However, the present invention is not limited to the configuration described in the above-described embodiment, and can be appropriately changed based on the description of the claims.

[0082] For example, as the type of battery to which the secondary battery according to the present invention is applied, a bipolar battery including a positive electrode active material layer electrically coupled to one surface of a current collector and a negative electrode active material layer electrically coupled to the opposite surface of the current collector is also included.

[0083] Further, the secondary battery according to the present embodiment does not have to be an all-solid type. That is, the solid electrolyte layer may further contain a conventionally known liquid electrolyte (electrolyte solution). There is no particular limitation on the amount of the liquid electrolyte (electrolyte solution) that can be contained in the solid electrolyte layer, but it is preferable that the amount is such that the shape of the solid electrolyte layer formed by the solid electrolyte is maintained and liquid leakage of the liquid electrolyte (electrolyte solution) does not occur.

[0084] The liquid electrolyte that can be used has a form in which a lithium salt is dissolved in an organic solvent. Examples of the organic solvent used include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propionate (MP), methyl acetate (MA), methyl formate (MF), 4-methyldioxolane (4MeDOL), dioxolane (DOL), 2-methyltetrahydrofuran (2MeTHF), tetrahydrofuran (THF), dimethoxyethane (DME), propylene carbonate (PC), butylene carbonate (BC), dimethyl sulfoxide (DMSO), and γ-butyrolactone (GBL). Among them, from the viewpoint of being able to further improve the rapid charging characteristics and output characteristics, the organic solvent is preferably a chain carbonate, more preferably at least one selected from the group consisting of diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC), and more preferably selected from ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC).

[0085] Examples of the lithium salt include Li(FSO2)2N (lithium bis(fluorosulfonyl)imide; LiFSI), Li(C2F5SO2)2N, LiPF6, LiBF4, LiClO4, LiAsF6, LiCF3SO3, etc. Among them, from the viewpoint of battery output and charge-discharge cycle characteristics, the lithium salt is preferably Li(FSO2)2N (LiFSI).

[0086] The liquid electrolyte may further contain additives other than the components described above. Specific examples of such compounds include, for example, ethylene carbonate, vinylene carbonate, methyl vinylene carbonate, dimethyl vinylene carbonate, phenyl vinylene carbonate, diphenyl vinylene carbonate, ethyl vinylene carbonate, diethyl vinylene carbonate, vinyl ethylene carbonate, 1,2-divinyl ethylene carbonate, 1-methyl-1-vinyl ethylene carbonate, 1-methyl-2-vinyl ethylene carbonate, 1-ethyl-1-vinyl ethylene carbonate, 1-ethyl-2-vinyl ethylene carbonate, vinyl vinylene carbonate, allyl ethylene carbonate, vinyloxy methyl ethylene carbonate, allyloxy methyl ethylene carbonate, acryloxy methyl ethylene carbonate, methacryloxy methyl ethylene carbonate, ethynyl ethylene carbonate, propargyl ethylene carbonate, ethynyloxy methyl ethylene carbonate, propargyloxy ethylene carbonate, methylene ethylene carbonate, 1,1-dimethyl-2-methylene ethylene carbonate, and the like. These additives may be used alone or in combination of two or more. Also, the amount of the additive used when used in the electrolyte can be adjusted as appropriate.

[0087] [Battery pack] A battery pack is formed by connecting a plurality of batteries. Specifically, at least two or more are used and it is configured by series connection, parallel connection, or both. By series and parallel connection, it becomes possible to freely adjust the capacity and voltage.

[0088] A plurality of batteries can also be connected in series or in parallel to form a small-sized assembled battery that can be detachably attached. Then, a plurality of such small-sized assembled batteries that can be detachably attached are further connected in series or in parallel to form an assembled battery with a large capacity and a large output suitable for a vehicle drive power source or an auxiliary power source that requires a high volumetric energy density and a high volumetric output density. The number of batteries to be connected to form the assembled battery and the number of stages of small-sized assembled batteries to be stacked to form a large-capacity assembled battery may be determined according to the battery capacity and output of the vehicle (electric vehicle) to be mounted.

[0089] [Vehicle] The secondary battery according to the present invention maintains its discharge capacity even after long-term use and has good cycle characteristics. Furthermore, it has a high volumetric energy density. In vehicle applications such as electric vehicles, hybrid electric vehicles, fuel cell vehicles, and hybrid fuel cell vehicles, compared with applications for electric and portable electronic devices, a high capacity and a large size are required, and a long service life is necessary. Therefore, the above non-aqueous electrolyte secondary battery can be suitably used as a power source for vehicles, for example, as a vehicle drive power source or an auxiliary power source.

[0090] Specifically, a battery or an assembled battery formed by combining a plurality of these can be mounted on a vehicle. In the present invention, since a high-life battery with excellent long-term reliability and output characteristics can be configured, mounting such a battery can configure a plug-in hybrid electric vehicle with a long EV driving range or an electric vehicle with a long single-charge driving range. A battery or an assembled battery formed by combining a plurality of these is used, for example, in an automobile such as a hybrid vehicle, a fuel cell vehicle, or an electric vehicle (all four-wheeled vehicles (commercial vehicles such as passenger cars, trucks, buses, and light automobiles), including two-wheeled vehicles (motorcycles) and three-wheeled vehicles), resulting in a high-life and highly reliable automobile. However, the application is not limited to automobiles. For example, it can also be applied to various power sources of other vehicles, such as trains, and can also be used as a mounting power source for an uninterruptible power supply device.

Example

[0091] [Example 1] (Fabrication of Solid Electrolyte Layer) Weighed 80 mg of sulfide solid electrolyte (Li 10 GeP2S 12 ; LGPS), placed it in an SLD sleeve (Φ10), clamped both ends with SLD pins plated with hard Cr, and pressed it at a pressure of 390 MPa for 1 minute at room temperature to obtain an electrolyte pellet.

[0092] Next, an SLD sleeve (Φ8) with a smaller diameter than the above SLD sleeve was placed at one end of the above electrolyte pellet, and sulfide solid electrolyte (Li 10 GeP2S 12 ) was weighed 12.8 mg and placed in the Φ8 sleeve, and pressed in the same manner as above for 1 minute to obtain an electrolyte pellet with the thickness of the outer peripheral edge portion on one end side being thinner than the inside of the outer peripheral edge portion.

[0093] Subsequently, the Φ8 sleeve was taken out, and 7.2 mg of a mixture of oxymethylene-bonded PEG400 and solid electrolyte (lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)) (the mixing ratio was controlled so that the molar ratio of lithium atoms contained in the solid electrolyte to oxygen atoms contained in oxymethylene-bonded PEG400 (Li / O) was 1 / 15) was weighed and placed in the depression of the outer peripheral edge portion of one end portion of the electrolyte pellet obtained above. Then, it was clamped again with SLD pins plated with hard Cr at both ends and pressed at a pressure of 390 MPa for 1 minute at room temperature to fabricate an electrolyte pellet (the solid electrolyte layer of this example).

[0094] (Fabrication of Anode Active Material Layer) A shielding plate was placed on the exposed portion of the solid electrolyte (LGPS) on the side where LiTFSI was arranged at the outer peripheral edge portion of the solid electrolyte layer fabricated above, and gold was deposited on the portion corresponding to the outer peripheral edge portion using a vacuum evaporation method. Subsequently, the shielding plate was removed, and metallic lithium was deposited on the exposed surface of the solid electrolyte layer and the front surface of the gold-deposited surface by a vacuum evaporation method. Then, both ends of the obtained laminate were clamped with SLD pins plated with hard Cr, and pressed at a pressure of 20 MPa for 3 hours at 60 °C to obtain a laminate of the solid electrolyte layer and the anode active material layer of this example (having the configuration shown in Figure 3).

[0095] [Example 2] First, a solid electrolyte layer of this example having a uniform composition made of LGPS was prepared without providing a region using a mixture of an oxymethylene-bonded PEG400 and a solid electrolyte (LiTFSI).

[0096] Next, in the same manner as in Example 1 described above, gold and lithium were vapor-deposited on one end side of the solid electrolyte layer to obtain a laminate of the solid electrolyte layer of this example and a negative electrode active material layer (having the configuration shown in FIG. 4).

[0097] [Example 3] First, a solid electrolyte layer of this example having a region using a mixture of an oxymethylene-bonded PEG400 and a solid electrolyte (LiTFSI) at the outer peripheral edge portion was prepared in the same manner as in Example 1 described above.

[0098] Next, a negative electrode active material layer of this example having a uniform composition made of metallic lithium was prepared without vapor-depositing gold, and a laminate of the solid electrolyte layer of this example and the negative electrode active material layer (having the configuration shown in FIG. 5) was obtained. [Explanation of Signs]

[0099] 10 All-solid-state lithium-ion secondary battery 11 Positive electrode current collector 12 Negative electrode current collector 13 Positive electrode active material layer 15 Negative electrode active material layer 15a Region where the partial molar volume of lithium in the region on the solid electrolyte layer side of the negative electrode active material layer corresponding to the outer peripheral edge portion is smaller than the region corresponding to the inside of the outer peripheral edge of the negative electrode active material layer 17 Electrolyte layer 17a Region where the partial molar volume of lithium ions in the region on the negative electrode active material layer side of the solid electrolyte layer corresponding to the outer peripheral edge portion is larger than the region corresponding to the inside of the outer peripheral edge of the solid electrolyte layer 19 Single cell layer 21 Power generation element 25 Positive electrode current collector plate (positive electrode tab) 27 Negative electrode current collector (negative electrode tab), 29 Laminate film, The outer peripheral edge of the interface between the P negative electrode active material layer and the solid electrolyte layer.

Claims

1. A positive electrode in which a positive electrode active material layer containing a positive electrode active material 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 containing metallic lithium or a lithium-containing alloy is disposed on the surface of a negative electrode current collector; A solid electrolyte layer containing a solid electrolyte, interposed between the positive electrode active material layer and the negative electrode active material layer; A power generation element having the above; In at least a part of the outer peripheral edge portion of the interface between the negative electrode active material layer and the solid electrolyte layer, in a region that does not extend to the end face of the negative electrode active material layer, the ratio of the lithium ion partial molar volume of the solid electrolyte layer to the lithium partial molar volume of the negative electrode active material layer has a value that is larger than that in the inner side of the outer peripheral edge portion at the interface, and there is a low reactivity region; The lithium ion partial molar volume of the region corresponding to the outer peripheral edge portion of the solid electrolyte layer is larger than that of the region corresponding to the inner side of the outer peripheral edge portion; A secondary battery in which the lithium partial molar volume of the region corresponding to the outer peripheral edge portion of the negative electrode active material layer is smaller than that of the region corresponding to the inner side of the outer peripheral edge portion.

2. A positive electrode in which a positive electrode active material layer containing a positive electrode active material 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 containing metallic lithium or a lithium-containing alloy is disposed on the surface of a negative electrode current collector; A solid electrolyte layer containing a solid electrolyte, interposed between the positive electrode active material layer and the negative electrode active material layer; A power generation element having the above; In at least a part of the outer peripheral edge portion of the interface between the negative electrode active material layer and the solid electrolyte layer, there is a low reactivity region where the ratio of the lithium ion partial molar volume of the solid electrolyte layer to the lithium partial molar volume of the negative electrode active material layer has a value that is larger than that in the inner side of the outer peripheral edge portion at the interface; The constituent material of the negative electrode active material layer is the same in the region corresponding to the outer peripheral edge portion and the region corresponding to the inner side of the outer peripheral edge portion; In the secondary battery, the partial molar volume of lithium ions in the region corresponding to the outer peripheral edge of the solid electrolyte layer is larger than that in the region corresponding to the inside of the outer peripheral edge, and the region corresponding to the outer peripheral edge of the solid electrolyte layer contains a lithium salt and a diluent.

3. A positive electrode in which a positive electrode active material layer containing a positive electrode active material 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 containing metallic lithium or a lithium-containing alloy is disposed on the surface of a negative electrode current collector; A solid electrolyte layer containing a solid electrolyte, interposed between the positive electrode active material layer and the negative electrode active material layer; And a power generation element having the above; At least a part of the outer peripheral edge of the interface between the negative electrode active material layer and the solid electrolyte layer, in a region that does not extend to the end face of the negative electrode active material layer, there is a low reactivity region where the value of the ratio of the partial molar volume of lithium ions in the solid electrolyte layer to the partial molar volume of lithium in the negative electrode active material layer is larger compared to the inside of the outer peripheral edge at the interface; The constituent material of the solid electrolyte layer is the same in the region corresponding to the outer peripheral edge and the region corresponding to the inside of the outer peripheral edge; In the secondary battery, the partial molar volume of lithium in the region corresponding to the outer peripheral edge of the negative electrode active material layer is smaller than that in the region corresponding to the inside of the outer peripheral edge.

4. The secondary battery according to any one of claims 1 to 3, wherein the solid electrolyte contains a sulfide solid electrolyte.

5. The secondary battery according to any one of claims 1 to 4, which is an all-solid-state lithium ion secondary battery.

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