Lithium secondary battery

Abstract

The purpose of the present invention is to provide a means making it possible to suppress a decrease in battery capacity or the occurrence of short-circuiting in a lithium deposition-based lithium secondary battery. One embodiment of the present invention pertains to a lithium secondary battery provided with a power generation element comprising: a positive electrode formed by arranging, on the surface of a positive electrode current collector, a positive electrode active material layer containing a positive electrode active material allowing for intercalation / deintercalation of lithium ions; a negative electrode which has a negative electrode current collector and in which lithium metal is deposited onto the negative electrode current collector during charging; a solid electrolyte layer that is interposed between the positive electrode and the negative electrode and contains a solid electrolyte. This lithium secondary battery is characterized in that: an ion-conducting reaction-suppressing layer that has lithium ion conductivity and suppresses a reaction between the lithium metal and the solid electrolyte is provided to at least part of a region where the positive electrode active material layer faces opposite the negative electrode current collector, on a principal surface where the solid electrolyte layer faces opposite the negative electrode current collector; the solid electrolyte extends as far as a plane direction end on the positive electrode side of the solid electrolyte layer; an ion permeation-suppressing layer for suppressing permeation of lithium ions is provided to the negative electrode-side plane direction end of the solid electrolyte layer; and at least part of the ion permeation-suppressing layer overlaps with the ion-conducting reaction-suppressing layer in plan view.

Description

Lithium secondary battery

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

[0002] In recent years, there has been a strong desire to reduce carbon dioxide emissions in order to combat global warming. In the automotive industry, there is growing hope for a reduction in carbon dioxide emissions through the introduction of electric vehicles (EVs) and hybrid electric vehicles (HEVs), and non-aqueous electrolyte secondary batteries, such as secondary batteries for driving motors, which hold the key to their practical application, have been actively developed.

[0003] Secondary batteries for driving motors are required to have extremely high output characteristics and high energy compared to consumer lithium-ion secondary batteries used in mobile phones, laptops, etc. Therefore, lithium-ion secondary batteries, which have the highest theoretical energy of all practical batteries, have attracted attention and are currently being rapidly developed.

[0004] Currently widely used lithium-ion secondary batteries use flammable organic electrolytes, and these liquid-based lithium-ion secondary batteries require stricter safety measures against leakage, short circuits, overcharging, and other issues than other batteries.

[0005] Therefore, in recent years, research and development on all-solid-state lithium secondary batteries using oxide-based or sulfide-based solid electrolytes has been actively conducted. Solid electrolytes are materials composed primarily of ionic conductors that can conduct ions in a solid state. Therefore, all-solid-state lithium secondary batteries do not, in principle, encounter the various problems associated with flammable organic electrolytes that occur in conventional liquid-based lithium-ion secondary batteries. Furthermore, the use of high-potential, high-capacity positive electrode materials and high-capacity negative electrode materials generally leads to significant improvements in the output density and energy density of the battery.

[0006] Conventionally, one type of all-solid-state lithium secondary battery known is a so-called lithium deposition type, in which lithium metal is deposited on a negative electrode current collector during charging. During the charging process of such a lithium deposition type all-solid-state lithium secondary battery, lithium metal is deposited between the solid electrolyte layer and the negative electrode current collector. U.S. Patent Application Publication No. 2019 / 0157723 discloses a technology in which a fine particle layer made of fine particles of amorphous carbon, silicon, silver, tin, aluminum, bismuth, or the like is disposed between the negative electrode current collector and the solid electrolyte layer, which constitute the power generating element of the lithium secondary battery. According to U.S. Patent Application Publication No. 2019 / 0157723, this configuration serves as a protective layer for the lithium metal layer when lithium metal is deposited between the fine particle layer and the negative electrode current collector during charging, and suppresses the growth of dendrites from the lithium metal layer, thereby preventing short circuits in the lithium secondary battery and resulting capacity reductions.

[0007] However, according to the investigations of the present inventors, it has been found that even if the technology described in U.S. Patent Application Publication No. 2019 / 0157723 is used, it may still not be possible to prevent a decrease in battery capacity or the occurrence of a short circuit due to dendrite growth.

[0008] Therefore, an object of the present invention is to provide a means for suppressing the decrease in battery capacity and the occurrence of short circuits in lithium deposition type lithium secondary batteries.

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result, have found that the above-mentioned problems can be solved by providing an ion-conductive reaction-inhibiting layer that has lithium ion conductivity and inhibits a reaction between lithium metal and the solid electrolyte on the negative electrode current collector side of the surface of the solid electrolyte layer facing the negative electrode current collector and in a region of the positive electrode active material layer facing the negative electrode current collector, and by providing an ion-permeation-inhibiting layer that inhibits the permeation of lithium ions at an end of the solid electrolyte layer in a surface direction on the negative electrode side, and by extending the solid electrolyte layer to the end of the surface direction on the positive electrode side, and by covering at least a portion of the ion-permeation-inhibiting layer with the ion-conductive reaction-inhibiting layer, thereby completing the present invention.

[0010] That is, one aspect of the present invention relates to a lithium secondary battery including a power generating element including: a positive electrode including a positive electrode active material layer disposed on a surface of a positive electrode current collector, the positive electrode active material layer containing a positive electrode active material capable of absorbing and releasing lithium ions; a negative electrode including a negative electrode current collector and in which lithium metal is deposited on the negative electrode current collector during charging; and a solid electrolyte layer interposed between the positive electrode and the negative electrode and containing a solid electrolyte. The lithium secondary battery is characterized in that an ion-conductive reaction-suppressing layer having lithium ion conductivity and suppressing a reaction between the lithium metal and the solid electrolyte is provided on at least a portion of a region of the main surface of the solid electrolyte layer facing the negative electrode current collector, the region being in a region where the positive electrode active material layer faces the negative electrode current collector, the solid electrolyte extending to a surface end of the solid electrolyte layer on the positive electrode side, and an ion-permeation-suppressing layer that suppresses permeation of lithium ions is provided on a surface end of the solid electrolyte layer on the negative electrode side, and at least a portion of the ion-permeation-suppressing layer overlaps with the ion-conductive reaction-suppressing layer in a plan view.

[0011] Fig. 1 is a perspective view showing the appearance of a flat stacked type all-solid-state lithium secondary battery according to one embodiment of the present invention. Fig. 2 is a cross-sectional view taken along line 2-2 shown in Fig. 1. Fig. 2 shows a cross-sectional view of the stacked secondary battery during charging. Fig. 3 is an enlarged cross-sectional view of a cell layer of a stacked secondary battery according to one embodiment of the present invention. Fig. 4 is an enlarged cross-sectional view of a cell layer of a stacked secondary battery according to another embodiment of the present invention. Fig. 5 is an enlarged cross-sectional view of a cell layer of a stacked secondary battery according to another embodiment of the present invention.

[0012] One embodiment of the present invention is a lithium secondary battery comprising: a power generating element including: a positive electrode including a positive electrode active material layer disposed on a surface of a positive electrode current collector, the positive electrode active material layer containing a positive electrode active material capable of absorbing and releasing lithium ions; a negative electrode having a negative electrode current collector, wherein lithium metal is deposited on the negative electrode current collector during charging; and a solid electrolyte layer interposed between the positive electrode and the negative electrode and containing a solid electrolyte, wherein an ion-conductive reaction-suppressing layer having lithium ion conductivity is provided on at least a portion of a region of the main surface of the solid electrolyte layer facing the negative electrode current collector, where the positive electrode active material layer faces the negative electrode current collector, the region being where the positive electrode active material layer faces the negative electrode current collector; the solid electrolyte layer extending to an end of the solid electrolyte layer in a planar direction on the positive electrode side; and an ion-permeation-suppressing layer that suppresses permeation of lithium ions is provided on an end of the solid electrolyte layer in a planar direction on the negative electrode side, and at least a portion of the ion-permeation-suppressing layer overlaps with the ion-conductive reaction-suppressing layer in a planar view. According to this embodiment, in a lithium deposition type lithium secondary battery, it is possible to suppress a decrease in battery capacity and the occurrence of a short circuit.

[0013] The present embodiment will be described below with reference to the drawings. However, the technical scope of the present invention should be determined based on the claims and is not limited to the following embodiments. Note that the dimensional ratios in the drawings are exaggerated for the convenience of explanation and may differ from the actual ratios. Hereinafter, when it is described that the surfaces of various parts are "flush with each other" or that the sizes of various parts are "the same (equal)," unless otherwise specified, it is sufficient that these are substantially the same, and manufacturing errors (for example, about ±5%) are included.

[0014] Fig. 1 is a perspective view showing the appearance of a flat stacked-type all-solid-state lithium secondary battery (hereinafter also simply referred to as a "stacked-type secondary battery") according to one embodiment of the present invention. Fig. 2 is a cross-sectional view taken along line 2-2 shown in Fig. 1. Fig. 2 shows a cross-sectional view of the stacked-type secondary battery during charging.

[0015] As shown in Fig. 1, the stacked secondary battery 10a has a flat rectangular shape, with a negative current collector 25 and a positive current collector 27 extending from both sides for extracting power. The power generating element 21 is wrapped in the battery exterior material (laminate film 29) of the stacked secondary battery 10a, and the periphery is heat-sealed, sealing the power generating element 21 with the negative current collector 25 and the positive current collector 27 extending to the outside. Note that the current collectors (25, 27) shown in Fig. 1 may be configured so that the negative current collector 25 and the positive current collector 27 extend from the same side, or the negative current collector 25 and the positive current collector 27 may each be divided into multiple plates and extended from each side.

[0016] As shown in FIG. 2 , the power generating element 21 of the stacked secondary battery 10 a of this embodiment has a configuration in which a negative electrode in which a negative electrode active material layer 13 containing lithium metal is disposed on both sides of a negative electrode current collector 11′, a solid electrolyte layer 17, and a positive electrode in which a positive electrode active material layer 15 containing a lithium transition metal composite oxide is disposed on both sides of a positive electrode current collector 11″ are laminated. Specifically, the negative electrode, solid electrolyte layer, and positive electrode are laminated in this order such that one negative electrode active material layer 13 and an adjacent positive electrode active material layer 15 face each other with the solid electrolyte layer 17 interposed therebetween. As a result, adjacent negative electrode, solid electrolyte layer, and positive electrode constitute one unit cell layer 19. Therefore, the stacked secondary battery 10 a shown in FIG. 2 can also be said to have a configuration in which a plurality of unit cell layers 19 are laminated and electrically connected in parallel.

[0017] A negative electrode current collector 25 and a positive electrode current collector 27 that are electrically connected to the respective electrodes (negative and positive electrodes) are attached to the negative electrode current collector 11′ and the positive electrode current collector 11″, respectively, and are configured to be sandwiched between the ends of the laminate film 29 and led out of the laminate film 29. The negative electrode current collector 25 and the positive electrode current collector 27 may be attached to the negative electrode current collector 11′ and the positive electrode current collector 11″ of the respective electrodes by ultrasonic welding, resistance welding, or the like, via a negative electrode terminal lead and a positive electrode terminal lead (not shown), respectively, as necessary.

[0018] In the above description, an embodiment of the lithium secondary battery according to the present invention has been described using a stacked (internal parallel connection) all-solid-state lithium secondary battery as an example. However, the type of lithium secondary battery to which the present invention is applicable is not particularly limited, and the present invention can also be applied to a bipolar lithium secondary battery.

[0019] FIG. 3 is an enlarged cross-sectional view of a cell layer 19 of a stacked secondary battery according to one embodiment of the present invention. As shown in FIG. 3 , the cell layer 19 constituting the stacked secondary battery 10 a according to this embodiment has a positive electrode composed of a positive electrode current collector 11″ and a positive electrode active material layer 15 disposed on the positive electrode current collector 11″. A solid electrolyte layer 17 containing a solid electrolyte is disposed on the surface of the positive electrode active material layer 15 opposite the positive electrode current collector 11″. In the embodiment shown in FIG. 3 , a carbon black layer 18 a containing carbon black nanoparticles is disposed on the main surface of the solid electrolyte layer 17 facing the negative electrode current collector 11′, in a region including the entire region where the positive electrode active material layer 15 faces the negative electrode current collector 11′ (in other words, a region slightly larger than the positive electrode active material layer 15 when the power generating element 21 is viewed from above). The carbon black constituting this carbon black layer 18 a has lithium ion conductivity, and therefore the carbon black layer 18 a can conduct lithium ions. Therefore, the provision of the carbon black layer 18 a does not impede the progress of the battery reaction. The carbon black layer 18a also has the function of suppressing a reaction between the lithium metal (negative electrode active material layer 13) deposited on the negative electrode current collector 11′ during charging and the solid electrolyte contained in the solid electrolyte layer 17. Therefore, the carbon black layer 18a can be said to function as an ion-conductive reaction suppression layer.

[0020] As shown in FIG. 3 , in the cell layer 19 constituting the stacked secondary battery 10 a according to this embodiment, the solid electrolyte layer 17 extends to the end of the positive electrode side (upper side in FIG. 3 ) of the solid electrolyte layer 17 in the planar direction. Meanwhile, a resin layer 18 b made of a resin sheet is provided around the end of the negative electrode side (lower side in FIG. 3 ) of the solid electrolyte layer 17 in the planar direction around the end. The resin constituting the resin layer 18 b is a material that does not have lithium ion conductivity. Therefore, the resin layer 18 b functions as an ion permeation suppression layer that suppresses the permeation of lithium ions. The resin layer 18 b (ion permeation suppression layer) is disposed so as to overlap the carbon black layer 18 a (ion-conductive reaction suppression layer) around the entire periphery in a plan view (viewed in the stacking direction) of the power generating element 21 (cell layer 19). In this manner, by arranging the resin layer 18b (ion permeation suppressing layer) so that at least a portion thereof overlaps with the carbon black layer 18a (ion-conductive reaction-suppressing layer), no gaps are formed in the in-plane direction between the ion-conductive reaction-suppressing layer and the ion permeation suppressing layer, thereby suppressing localized precipitation of lithium metal (dendrite formation). Furthermore, by providing the ion permeation suppressing layer at the end portions, dendrite growth at the end portions of the ion-conductive reaction-suppressing layer can be suppressed. Furthermore, by providing the ion permeation suppressing layer at the end portions in the in-plane direction on the negative electrode side of the solid electrolyte layer, while extending the solid electrolyte layer to the end portions in the in-plane direction on the positive electrode side, dendrite formation due to cracks in the ion-conductive reaction-suppressing layer that occur during the roll-pressing process in fabricating the unit cell layers can be prevented.

[0021] As described above, in the embodiment shown in FIG. 3 , the positive electrode active material layer 15 is provided between the solid electrolyte layer 17 and the positive electrode current collector 11″. In other words, the solid electrolyte layer 17 faces the positive electrode current collector 11″ with the positive electrode active material layer 15 therebetween. Furthermore, the negative electrode active material layer 13 and the carbon black layer 18a (ion-conductive reaction-suppressing layer) are provided between the solid electrolyte layer 17 and the negative electrode current collector 11′. In other words, the solid electrolyte layer 17 faces the negative electrode current collector 11′ with the negative electrode active material layer 13 and the carbon black layer 18a (ion-conductive reaction-suppressing layer) therebetween.

[0022] In the stacked secondary battery 10a according to this embodiment, the power generating element 21 sealed in the laminate film 29 shown in FIG. 1 is preferably sandwiched between two plate-shaped members and further fastened using a fastening member. As a result, the plate-shaped members and fastening members function as pressure members that pressurize (restrain) the power generating element 21 in the stacking direction. Examples of the plate-shaped members include metal plates and resin plates. Examples of the fastening members include bolts and nuts. However, the pressure members are not particularly limited as long as they can pressurize the power generating element 21 in the stacking direction. A typical pressure member is a combination of a plate made of a rigid material, like the plate-shaped members, and the fastening members described above. Furthermore, the fastening members may be not only bolts and nuts, but also tension plates or the like that secure the ends of the plate-shaped members so as to restrain the power generating element 21 in the stacking direction. The lower limit of the load applied to the power generating element 21 (constraint pressure in the stacking direction of the power generating element) is, for example, 0.1 MPa or more, preferably 1 MPa or more, more preferably 3 MPa or more, and even more preferably 5 MPa or more. The upper limit of the constraint pressure in the stacking direction of the power generating element is, for example, 100 MPa or less, preferably 70 MPa or less, more preferably 40 MPa or less, and even more preferably 10 MPa or less.

[0023] The main components of the stacked secondary battery 10a will be described below.

[0024] [Current Collectors (Positive Electrode Current Collector and Negative Electrode Current Collector)] The positive electrode current collector and the negative electrode current collector are conductive members that function as electron flow paths during battery reactions (charging and discharging), and have, for example, a thin plate (foil) shape. The negative electrode current collector faces the positive electrode current collector with the power generating element (solid electrolyte layer) in between. There are no particular restrictions on the materials that make up the positive electrode current collector and the negative electrode current collector. For example, metals or conductive resins are used as materials for the positive electrode current collector and the negative electrode current collector.

[0025] Examples of metals include aluminum (Al), nickel (Ni), iron (Fe), stainless steel (SUS), titanium (Ti), and copper (Cu). Other examples include clad materials of nickel and aluminum, and clad materials of copper and aluminum. Foils in which aluminum is coated on a metal surface may also be used. Among these, aluminum, stainless steel, copper, and nickel are preferred from the viewpoints of electronic conductivity, battery operating potential, and the like. Examples of conductive resins include resins in which a conductive filler is added to a non-conductive polymeric material.

[0026] There is no particular limitation on the thickness of the positive electrode current collector and the negative electrode current collector, but it is, for example, 10 to 100 μm.

[0027] The positive electrode current collector and the negative electrode current collector may have a single layer structure made of a single material, or may have a laminate structure made of an appropriate combination of layers made of these materials. From the viewpoint of weight reduction, the positive electrode current collector and the negative electrode current collector preferably contain a conductive resin made of at least a resin having electrical conductivity. Furthermore, from the viewpoint of blocking the movement of lithium ions between the single cell layers, a metal layer may be provided on a portion of the positive electrode current collector and the negative electrode current collector. The planar shape of the positive electrode current collector and the negative electrode current collector is, for example, a rectangular shape, a circle, an ellipse, or the like. The planar shape of the positive electrode current collector and the negative electrode current collector is, for example, approximately the same size.

[0028] [Positive Electrode Active Material Layer] The positive electrode constituting the lithium secondary battery according to this embodiment has a positive electrode active material layer containing a positive electrode active material capable of absorbing and releasing lithium ions. The positive electrode active material layer 15 is made of, for example, NMC811 (lithium nickel cobalt manganese oxide; LiNi ０．８ Co ０．１ Mn ０．１ O ２Preferably, the cathode active material layer 15 is formed using an NMC composite oxide such as CrNbO3 as a main raw material. The cathode active material layer 15 also preferably includes a cathode active material layer containing sulfur. The type of sulfur-containing cathode active material is not particularly limited, but examples include elemental sulfur (S), as well as particles or thin films of organic sulfur compounds or inorganic sulfur compounds. Any material may be used as long as it utilizes the oxidation-reduction reaction of sulfur to release lithium ions during charging and absorb lithium ions during discharging.

[0029] The thickness (size in the stacking direction) of the positive electrode active material layer 15 varies depending on the intended configuration of the lithium secondary battery, but is preferably within the range of 0.1 to 1000 μm, and more preferably 40 to 100 μm.

[0030] The content of the positive electrode active material in the positive electrode active material layer is not particularly limited, but is preferably within a range of 30 to 99% by mass, more preferably within a range of 40 to 90% by mass, and even more preferably within a range of 45 to 80% by mass.

[0031] In the lithium secondary battery according to this embodiment, the positive electrode active material layer 15 preferably further contains a solid electrolyte. Examples of the solid electrolyte include a sulfide solid electrolyte, a resin solid electrolyte, and an oxide solid electrolyte. In this specification, the term "solid electrolyte" refers to a material mainly composed of an ion conductor capable of conducting ions in a solid state, and in particular, a material having a lithium ion conductivity of 1×10 at room temperature (25° C.). −５ S / cm or more, and this lithium ion conductivity is preferably 1×10 −４ The ionic conductivity is 200 S / cm or more. Here, the value of the ionic conductivity can be measured by an AC impedance method.

[0032] In another preferred embodiment of the secondary battery according to the present aspect, the solid electrolyte is preferably a sulfide solid electrolyte containing an S element, from the viewpoint of exhibiting excellent lithium ion conductivity and being able to better follow the volume change of the electrode active material that accompanies charge and discharge, more preferably a sulfide solid electrolyte containing a Li element, an M element, and an S element, wherein the M element contains at least one element selected from the group consisting of P, Si, Ge, Sn, Ti, Zr, Nb, Al, Sb, Br, Cl, and I, and even more preferably a sulfide solid electrolyte containing an S element, a Li element, and a P element.

[0033] The sulfide solid electrolyte is Li ３ P.S. ４ It may have a Li framework. ４ P ２ S ７ It may have a Li framework. ４ P ２ S ６ It may have a Li skeleton. ３ P.S. ４ Examples of sulfide solid electrolytes having a framework include LiI-Li ３ P.S. ４ , LiI-LiBr-Li ３ P.S. ４ , Li ３ P.S. ４ In addition, Li ４ P ２ S ７ Examples of sulfide solid electrolytes having a skeleton include Li-P-S solid electrolytes called LPS. （４−ｘ） Ge （１−ｘ） P ｘ S ４ (x satisfies 0<x<1) or the like. More specifically, for example, LPS (Li ２ S-P ２ S ５ ), Li ７ P ３ S １１ , Li ３．２ P ０．９６ S., Li. ３．２５ Ge ０．２５ P ０．７５ S４ , Li １０ GeP ２ S １２ , or Li ６ P.S. ５ X (wherein X is Cl, Br or I). ２ S-P ２ S ５ " is written by Li ２ S and P ２ S ５ The same applies to other descriptions. Among them, the sulfide solid electrolyte is preferably LPS (Li ２ S-P ２ S ５ ), Li ６ P.S. ５ X (wherein X is Cl, Br or I), Li ７ P ３ S １１ , Li ３．２ P ０．９６ S and Li ３ P.S. ４ is selected from the group consisting of:

[0034] The content of the solid electrolyte in the positive electrode active material layer is not particularly limited, but is preferably in the range of 1 to 70 mass %, more preferably in the range of 10 to 60 mass %, and even more preferably in the range of 20 to 55 mass %.

[0035] The positive electrode active material layer may further contain at least one of a conductive additive and a binder in addition to the positive electrode active material and the solid electrolyte. The thickness of the positive electrode active material layer varies depending on the configuration of the intended lithium secondary battery, but is preferably within a range of 0.1 to 1000 μm, and more preferably 40 to 100 μm.

[0036] [Solid Electrolyte Layer] The solid electrolyte layer is a layer interposed between the positive electrode active material layer and the negative electrode current collector, and contains a solid electrolyte (usually as a main component).

[0037] The solid electrolyte layer interposed between the positive electrode active material layer and the ion-conductive reaction suppression layer contains a solid electrolyte as a main component. Examples of this solid electrolyte include sulfide solid electrolytes and oxide solid electrolytes, but sulfide solid electrolytes are preferred. Examples of sulfide solid electrolytes include LPS-based (e.g., Argyrodite (Li ６ P.S. ５ Cl), LGPS system (e.g. Li １０ GeP ２ S １２ ) materials can be mentioned.

[0038] The content of the solid electrolyte in the solid electrolyte layer is, for example, preferably in the range of 10 to 100 mass %, more preferably in the range of 50 to 100 mass %, and even more preferably in the range of 90 to 100 mass %, relative to the total mass of the solid electrolyte layer.

[0039] The thickness of the solid electrolyte layer varies depending on the intended configuration of the lithium secondary battery, but is preferably within the range of 0.1 to 1000 μm, and more preferably 10 to 40 μm.

[0040] [Negative Electrode Active Material Layer] The lithium secondary battery according to this embodiment is a so-called lithium deposition type in which lithium metal is deposited on the negative electrode current collector during the charging process. The layer of lithium metal deposited on the negative electrode current collector during this charging process is the negative electrode active material layer of the lithium secondary battery according to this embodiment. Therefore, the thickness of the negative electrode active material layer increases as the charging process progresses, and the thickness of the negative electrode active material layer decreases as the discharging process progresses. Although the negative electrode active material layer does not need to be present during full discharge, in some cases, a negative electrode active material layer composed of a certain amount of lithium metal may be present during full discharge. Furthermore, the thickness of the negative electrode active material layer (lithium metal layer) during full charge is not particularly limited, but is typically 0.1 to 1000 μm.

[0041] [Ion-Conductive Reaction-Inhibiting Layer] In the lithium secondary battery according to this embodiment, as shown in FIG. 3 , an ion-conductive reaction-inhibiting layer (carbon black layer 18a) is provided on at least a portion (preferably the entirety) of the region of the main surface of the solid electrolyte layer 17 facing the negative electrode current collector 11′ where the positive electrode active material layer 15 faces the negative electrode current collector 11′. This ion-conductive reaction-inhibiting layer has lithium ion conductivity and inhibits the reaction between lithium metal (negative electrode active material layer) and the solid electrolyte. Therefore, by providing the ion-conductive reaction-inhibiting layer, it is possible to prevent degradation of the solid electrolyte and a decrease in battery capacity caused by the reaction between lithium metal (negative electrode active material layer) and the solid electrolyte without impeding the progress of the battery reaction.

[0042] Here, a material "has lithium ion conductivity" means that the lithium ion conductivity of the material at 25°C is 1×10 −４ On the other hand, when a material "does not have lithium ion conductivity," it means that the lithium ion conductivity of the material at 25°C is 1 × 10 −４ In the lithium secondary battery according to the present embodiment, the lithium ion conductivity of the constituent material of the ion-conductive reaction suppression layer at 25° C. is less than 1×10 −４ [S / cm] or more, preferably 1.5 × 10 −４ [S / cm] or more, more preferably 2.0 × 10 −４ [S / cm] or more, and more preferably 2.5 × 10 −４ [S / cm] or more, and particularly preferably 3.0 × 10 −４ [S / cm] or more.

[0043] The constituent material of the ion-conductive reaction suppression layer is not particularly limited, and various materials capable of exhibiting the above-mentioned functions can be employed. One example of a constituent material of the ion-conductive reaction suppression layer is nanoparticles having lithium ion conductivity (herein, nanoparticles as a constituent material of the ion-conductive reaction suppression layer are also simply referred to as "first nanoparticles"). By including the first nanoparticles in the ion-conductive reaction suppression layer, a lithium secondary battery with particularly excellent ion-conductive reaction suppression layer functionality can be provided. Here, "nanoparticles" refers to particles having an average particle diameter on the nanometer (nm) scale. The "average particle diameter" of nanoparticles refers to the 50% cumulative diameter (D50) of the particle diameter (the maximum distance between any two points on the outline of the observed particle) measured by observing the cross section of a layer containing the nanoparticles with a scanning electron microscope (SEM). The average particle diameter of the first nanoparticles is preferably 500 nm or less, more preferably 300 nm or less, even more preferably 150 nm or less, particularly preferably 100 nm or less, and most preferably 60 nm or less. In particular, when the average particle size of the first nanoparticles is 60 nm or less, a lithium secondary battery having a particularly excellent dendrite growth suppression effect can be provided. Note that there is no particular limit on the lower limit of the average particle size of the first nanoparticles, but it is usually 10 nm or more, and preferably 20 nm or more.

[0044] From the viewpoint of particularly excellent function as an ion-conductive reaction suppression layer, such first nanoparticles preferably contain one or more elements selected from the group consisting of carbon, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, and zinc, and more preferably comprise one or more of these elements as simple substances or alloys. Furthermore, the first nanoparticles preferably contain carbon, and more preferably comprise simple carbon. Examples of such materials comprised of simple carbon include acetylene black, Vulcan (registered trademark), Black Pearl (registered trademark), carbon nanofiber, Ketjen Black (registered trademark), carbon nanotubes, carbon nanohorns, carbon nanoballoons, and fullerenes. When the ion-conductive reaction suppression layer contains such nanoparticles, the layer may further contain a binder.

[0045] There are no particular limitations on the method for forming the ion-conductive reaction suppression layer containing the first nanoparticles described above on the surface of the solid electrolyte layer facing the negative electrode current collector. For example, a method can be used in which a slurry containing the nanoparticles and, if necessary, a binder dispersed in an appropriate solvent is applied to the surface of the solid electrolyte layer facing the negative electrode current collector, and the solvent is then dried. Alternatively, the slurry can be applied to the surface of a support such as stainless steel foil, the solvent is dried, and the resulting coating is bonded to the surface of the solid electrolyte layer facing the negative electrode current collector using a method such as hydrostatic pressing, and the support is then peeled off to form the ion-conductive reaction suppression layer. In some cases, the ion-conductive reaction suppression layer can be formed by forming a continuous layer containing any of the above-mentioned materials by a method such as sputtering, rather than in the form of nanoparticles.

[0046] The first nanoparticles as the constituent material of the ion-conductive reaction-suppressing layer have been described above, but the ion-conductive reaction-suppressing layer containing the first nanoparticles described above usually has electronic conductivity. If the ion-conductive reaction-suppressing layer has electronic conductivity, it is preferable because it can further improve the resistance to rapid charging.

[0047] However, in another preferred embodiment, the ion-conductive reaction suppression layer is electronically insulating. Examples of electronically insulating constituent materials for the ion-conductive reaction suppression layer include lithium halides (lithium fluoride (LiF), lithium chloride (LiCl), lithium bromide (LiBr), and lithium iodide (LiI)), composite metal oxides represented by Li-M-O (wherein M is one or more metal elements selected from the group consisting of Mg, Au, Al, Sn, and Zn), and Li-Ba-TiO ３ Examples of suitable lithium-containing compounds include one or more lithium-containing compounds selected from the group consisting of composite oxides. All of these materials are more stable than solid electrolytes with respect to reductive decomposition upon contact with lithium metal. That is, when comparing the tendency of the solid electrolyte constituting the solid electrolyte layer to undergo reductive decomposition upon contact with lithium metal with the tendency of the lithium-containing compound constituting the ion-conductive reaction suppression layer to undergo reductive decomposition upon contact with lithium metal, the latter tendency is smaller. Therefore, the lithium-containing compound can also function as an ion-conductive reaction suppression layer. There are no particular limitations on the method for forming the ion-conductive reaction suppression layer containing such a lithium-containing compound. For example, the ion-conductive reaction suppression layer can be formed by forming a continuous layer containing the lithium-containing compound by a method such as sputtering.

[0048] The average thickness of the ion-conductive reaction suppression layer is not particularly limited, as long as it is disposed at a thickness that allows the above-described functions to be exhibited. For example, when the ion-conductive reaction suppression layer is a layer containing first nanoparticles, the average thickness is preferably 300 nm to 20 μm, more preferably 500 nm to 15 μm, and even more preferably 1 to 10 μm. Furthermore, when the layer is a continuous layer made of a lithium-containing compound formed by a technique such as sputtering, the average thickness is preferably 0.5 to 20 nm. The "average thickness" of the ion-conductive reaction suppression layer refers to the value calculated as the arithmetic mean value of thickness measurements taken at several to several dozen different locations on the ion-conductive reaction suppression layer constituting a lithium secondary battery.

[0049] The Young's modulus of the ion-conductive reaction suppression layer is preferably 2 GPa or more, more preferably 5 GPa or more, particularly preferably 8 GPa or more, and particularly preferably 10 GPa or more. When the ion-conductive reaction suppression layer exhibits such a high Young's modulus, even if dendrites are generated from lithium metal precipitated during rapid charging, the occurrence of an internal short circuit due to the dendrites penetrating the solid electrolyte layer and reaching the positive electrode active material layer can be effectively prevented. In this specification, the Young's modulus value is a value measured in accordance with JIS K 7161-1:2014.

[0050] [Ion Permeation Suppressing Layer] The lithium secondary battery according to this embodiment is also characterized in that an ion permeation suppressing layer (resin layer 18b) is provided on at least a portion (preferably the entire periphery) of the end portion of the solid electrolyte layer 17 in the surface direction on the negative electrode side, as shown in Fig. 3 . This ion permeation suppressing layer is a layer that suppresses the permeation of lithium ions. Therefore, by providing the ion permeation suppressing layer, even if dendrites are generated from the lithium metal in the negative electrode active material layer 13, it is possible to effectively prevent the occurrence of a short circuit caused by the dendrites growing while bypassing the periphery of the solid electrolyte layer 17.

[0051] There are no particular limitations on the material of the ion permeation suppression layer, and various materials capable of exhibiting the above-mentioned functions can be used. The material of the ion permeation suppression layer is preferably a material that does not have lithium ion conductivity. In the lithium secondary battery according to this embodiment, the material of the ion permeation suppression layer has a lithium ion conductivity of 1×10 at 25° C. −４ [S / cm], but preferably less than 1×10 −５ [S / cm] or less, more preferably 1×10 −６ [S / cm] or less, and more preferably 1×10 −７ [S / cm] or less, and particularly preferably 1×10 −８[S / cm] or less. When the lithium ion conductivity of the constituent material of the ion permeation suppressing layer is within these ranges, the effect of suppressing lithium ion permeation is particularly high. Furthermore, as the relative relationship between the lithium ion conductivity of the constituent material of the ion-conductive reaction suppressing layer and the lithium ion conductivity of the constituent material of the ion permeation suppressing layer, the lithium ion conductivity (25°C) of the constituent material of the ion-conductive reaction suppressing layer is preferably 10 times or more, more preferably 100 times or more, even more preferably 300 times or more, and particularly preferably 500 times or more than the lithium ion conductivity (25°C) of the constituent material of the ion permeation suppressing layer. When the lithium ion conductivities of the respective materials differ by this extent, it can be said that the constituent materials of each layer exhibit lithium ion conductivities that are preferable.

[0052] Examples of materials that can be used to form the ion permeation suppression layer include resin materials, rubber materials, and inorganic powders such as S-B-Na-based glass frit. Among these, resin materials and rubber materials (particularly resin materials) have elasticity, so that even if internal stress occurs in the region where the ion permeation suppression layer is formed, the ion permeation suppression layer can stretch without breaking, thereby effectively preventing the occurrence of a short circuit.Examples of such resin materials or rubber materials include 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, 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, styrene-isoprene-styrene block copolymer and hydrogenated products thereof, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene, and the like. Fluorine resins such as ethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polyvinyl fluoride (PVF), etc., vinylidene fluoride-hexafluoropropylene fluororubber (VDF-HFP fluororubber), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene fluororubber (VDF-HFP-TFE fluororubber), vinylidene fluoride-pentafluoropropylene fluororubber (VDF-PFP fluororubber), etc. vinylidene fluoride-based fluororubbers such as vinylidene fluoride-pentafluoropropylene-tetrafluoroethylene-based fluororubbers (VDF-PFP-TFE-based fluororubbers), vinylidene fluoride-perfluoromethylvinyl ether-tetrafluoroethylene-based fluororubbers (VDF-PFMVE-TFE-based fluororubbers) and vinylidene fluoride-chlorotrifluoroethylene-based fluororubbers (VDF-CTFE-based fluororubbers), and epoxy resins.

[0053] Nanoparticles without lithium ion conductivity (herein, nanoparticles serving as a constituent material of the ion permeation suppression layer are also simply referred to as "second nanoparticles") may be used as a constituent material of the ion permeation suppression layer. The average particle diameter of the second nanoparticles is preferably 500 nm or less, more preferably 300 nm or less, even more preferably 150 nm or less, even more preferably 100 nm or less, particularly preferably 70 nm or less, and most preferably 40 nm or less. In particular, when the average particle diameter of the second nanoparticles is 40 nm or less, a lithium secondary battery having a particularly excellent dendrite growth suppression effect can be provided. Note that there is no particular limit on the lower limit of the average particle diameter of the second nanoparticles, but it is usually 10 nm or more, preferably 20 nm or more.

[0054] From the viewpoint of low lithium ion conductivity and effective suppression of dendrite growth, the second nanoparticles preferably contain a metal oxide or nitride. Examples of such metal oxides or nitrides include oxides or nitrides of metals such as aluminum, silicon, magnesium, calcium, potassium, tin, sodium, boron, titanium, lead, zirconium, and yttrium. Among these, the second nanoparticles preferably contain an oxide of these metals, more preferably an oxide of aluminum (aluminum oxide; alumina) or an oxide of silicon (silicon oxide; silica), and even more preferably alumina. When the ion permeation suppression layer contains such nanoparticles, the layer may further contain a binder.

[0055] Furthermore, the Young's modulus of the ion permeation suppression layer is preferably approximately the same as that of the solid electrolyte layer (within ±10%), which can prevent cracking of the ion-conductive reaction suppression layer during processes such as roll pressing during cell manufacturing.

[0056] There are no particular limitations on the method for forming the ion permeation suppression layer on the surface of the negative electrode-side end of the solid electrolyte layer. For example, a method may be used in which a slurry containing the nanoparticles and, if necessary, a binder dispersed in an appropriate solvent is applied to the surface of the end of the solid electrolyte layer, and the solvent is then dried and rolled using a roll press to embed the ion permeation suppression layer in the surface of the end of the solid electrolyte layer. Alternatively, the slurry may be applied to the surface of a support such as stainless steel foil, the solvent is dried, and the resulting coating is bonded to the surface of the end of the solid electrolyte layer using a method such as a hydrostatic press, and then rolled with or without the support to form the ion permeation suppression layer. Furthermore, instead of applying or transferring the slurry, the ion permeation suppression layer may be formed by disposing an insulating film such as a resin film and then similarly rolling the film. Alternatively, the surface of the end of the solid electrolyte layer may be countersunk in advance, and the ion permeation suppression layer may be disposed or coated on top of the countersunk film.

[0057] In a preferred embodiment of the present invention, the solid electrolyte layer is composed of a sheet integrated with the ion permeation suppression layer. In this case, it is more preferable that the solid electrolyte layer includes a fibrous support, thereby configuring the solid electrolyte layer as a self-supporting sheet integrated with the ion permeation suppression layer. With this configuration, the solid electrolyte layer integrated with the ion permeation suppression layer can be subjected to a rolling process to produce a laminate with other layers, thereby simplifying the manufacturing process and improving productivity.

[0058] 3, the outer peripheral edge of the ion-conductive reaction-suppressing layer is located inside the outer peripheral edge of the ion permeation-suppressing layer in a plan view. This configuration can suppress Li precipitation at the outer peripheral edge of the ion permeation-suppressing layer, thereby suppressing capacity degradation due to Li precipitation (dendrites). However, in some cases, the outer peripheral edge of the ion-conductive reaction-suppressing layer may coincide with the outer peripheral edge of the ion permeation-suppressing layer in a plan view.

[0059] 3 , the outer peripheral edge of the solid electrolyte layer coincides with the outer peripheral edge of the ion permeation suppressing layer in a plan view. This configuration can suppress Li precipitation from the outer peripheral edge of the ion permeation suppressing layer, thereby suppressing capacity degradation due to Li dendrites at the end of the solid electrolyte layer. However, in some cases, the outer peripheral edge of the solid electrolyte layer may be located inside (or outside) the outer peripheral edge of the ion permeation suppressing layer in a plan view.

[0060] In the embodiment shown in Figure 3, the inner peripheral edge of the ion permeation suppression layer is located outside the outer peripheral edge of the positive electrode active material layer in a plan view. This configuration can suppress an increase in internal resistance at the end of the positive electrode active material layer. In other words, by having the inner peripheral edge of the ion permeation suppression layer located outside the outer peripheral edge of the positive electrode active material layer, the positive electrode active material layer can be more effectively utilized. However, in some cases, the inner peripheral edge of the ion permeation suppression layer may coincide with the outer peripheral edge of the positive electrode active material layer in a plan view, or may be located inside this.

[0061] In the embodiment shown in FIG. 3 , the main surface of the solid electrolyte layer facing the negative electrode current collector and the negative electrode-side surface of the ion permeation suppression layer are flush with each other. This configuration can suppress cracking due to shear stress at the interface between the ion permeation suppression layer and the solid electrolyte layer during processes such as roll pressing during cell fabrication. As a result, the growth of Li dendrites due to cracking can be suppressed. However, in some cases, the main surface of the solid electrolyte layer facing the negative electrode current collector and the negative electrode-side surface of the ion permeation suppression layer do not need to be flush with each other. For example, the negative electrode-side surface of the ion permeation suppression layer may protrude toward the negative electrode beyond the main surface of the solid electrolyte layer.

[0062] The thickness of the ion permeation suppression layer is preferably half or less than the thickness of the solid electrolyte layer. Here, in the cell manufacturing process, the thicker the ion permeation suppression layer, the more likely it is that cracks will occur due to the difference in elastic modulus between the ion permeation suppression layer and the solid electrolyte layer during processes such as roll pressing. Therefore, the thickness of the ion permeation suppression layer is more preferably 25% or less of the thickness of the solid electrolyte layer, more preferably 20% or less, even more preferably 15% or less, and particularly preferably 10% or less.

[0063] 4 and 5 are enlarged cross-sectional views of unit cell layers of a stacked secondary battery according to another embodiment of the present invention. In the embodiment shown in Fig. 4 and Fig. 5, the thickness of the ion permeation suppression layer (resin layer 18b) is greater at the outer peripheral end of the surface direction of the negative electrode side than at the inner peripheral end of the surface direction of the negative electrode side. This configuration can further suppress Li dendrites at the end, thereby further improving cycle characteristics.

[0064] The lithium secondary battery according to this embodiment is preferably an all-solid-state lithium secondary battery. All-solid-state lithium secondary batteries operate, for example, under a predetermined confining pressure applied in the stacking direction of the power generating element. When the all-solid-state battery is charged, a negative electrode active material layer made of lithium metal is formed between the negative electrode current collector and the ion-conductive reaction-suppressing layer. This negative electrode active material layer is formed when lithium (Li) ions in the positive electrode active material layer pass through the solid electrolyte layer and are deposited as lithium metal on the surface of the negative electrode current collector. Meanwhile, when the all-solid-state lithium secondary battery is discharged, lithium ions pass through the solid electrolyte layer from the negative electrode active material layer and are absorbed into the positive electrode active material. Therefore, the negative electrode active material layer usually disappears at an SOC of 0% (SOC of 100% is a fully charged state).

[0065] The lithium secondary battery according to the present embodiment does not have to be an all-solid-state type. That is, the solid electrolyte layer may further contain a conventionally known liquid electrolyte (electrolytic solution). There is no particular limitation on the amount of liquid electrolyte (electrolytic solution) that can be contained in the solid electrolyte layer, but it is preferably an amount that maintains the shape of the solid electrolyte layer formed by the solid electrolyte and prevents leakage of the liquid electrolyte (electrolytic solution). As the liquid electrolyte (electrolytic solution), a solution in the form of a conventionally known lithium salt dissolved in a conventionally known organic solvent is used. The liquid electrolyte (electrolytic solution) may further contain additives other than the organic solvent and the lithium salt. These additives may be used alone or in combination of two or more. Furthermore, when an additive is used in the electrolyte solution, the amount used can be adjusted appropriately.

[0066] The present invention will be described in more detail below with reference to examples. However, the technical scope of the present invention is not limited to the following examples. Note that the following operations were performed in a glove box. Furthermore, the instruments and devices used in the glove box were thoroughly dried beforehand.

[0067] [Example of Fabrication of All-Solid-State Lithium Secondary Battery] First, LiNi as a positive electrode active material ０．８ Mn ０．１ Co ０．１ O ２ , acetylene black as a conductive additive, and a sulfide solid electrolyte (LPS(Li ２ S-P ２ S ５ )) were weighed out to a mass ratio of 70:5:25, mixed in an agate mortar in a glove box, and then further mixed and stirred in a planetary ball mill. 2 parts by mass of styrene-butadiene rubber (SBR) was added to 100 parts by mass of the resulting mixed powder, and mesitylene was added as a solvent to prepare a positive electrode active material slurry. The positive electrode active material slurry prepared above was then applied to the surface of a stainless steel (SUS) foil serving as a positive electrode current collector and dried to form a positive electrode active material layer, thereby producing a positive electrode.

[0068] Sulfide solid electrolyte (LPS (Li ２ S-P ２ S５ )) 2 parts by mass of the same styrene-butadiene rubber (SBR) as above was added to 100 parts by mass of the above-mentioned styrene-butadiene rubber (SBR), and mesitylene was added as a solvent to prepare a solid electrolyte slurry. The solid electrolyte slurry prepared above was then coated on the surface of a stainless steel foil as a support and dried to prepare a solid electrolyte layer on the surface of the stainless steel foil. An insulating film (PET film) was then placed on the prepared solid electrolyte layer as an ion permeation suppression layer, and the thickness was made uniform by roll pressing to prepare a solid electrolyte layer in which an ion permeation suppression layer made of PET film was placed around the entire periphery of the negative electrode side end of the solid electrolyte layer.

[0069] Next, the positive electrode and the solid electrolyte layer prepared above were stacked so that the surfaces thereof on which the ion permeation suppression layer was not disposed faced each other, and then they were bonded together using a hydrostatic press (700 MPa, 25°C, 1 minute). The stainless steel foil on the solid electrolyte layer side was peeled off, and a laminate of positive electrode current collector / positive electrode active material layer / solid electrolyte layer (including the ion permeation suppression layer) was obtained.

[0070] On the other hand, carbon black nanoparticles were prepared as a constituent material of the ion-conductive reaction suppression layer. 10 parts by mass of the same styrene-butadiene rubber (SBR) as described above was added to 100 parts by mass of these carbon black nanoparticles, and mesitylene was added as a solvent to prepare a carbon black nanoparticle slurry. The carbon black nanoparticle slurry prepared above was then applied to the surface of a stainless steel foil support and dried to form a carbon black layer as an ion-conductive reaction suppression layer on the surface of the stainless steel foil. The outer periphery of the carbon black layer (ion-conductive reaction suppression layer) was slightly larger than the region where the positive electrode active material layer faces the negative electrode current collector, as shown in FIG. 3, and slightly smaller than the outer periphery of the solid electrolyte layer.

[0071] The cathode current collector / cathode active material layer / solid electrolyte layer (including the ion permeation suppression layer) laminate was then stacked so that the solid electrolyte layer and the carbon black layer (ion-conductive reaction-suppressing layer) faced each other, and the two were then bonded together using a hydrostatic press (700 MPa, 25°C, 1 minute). The stainless steel foil on the carbon black layer side was peeled off, forming a carbon black layer in the center of the solid electrolyte layer. Finally, stainless steel foil was placed as an anode current collector to cover the carbon black layer formed above, thereby producing the lithium deposition-type all-solid-state lithium secondary battery shown in Figure 3, except that the anode active material layer was not present.

Claims

1. a positive electrode including a positive electrode active material layer disposed on a surface of a positive electrode current collector, the positive electrode active material layer containing a positive electrode active material capable of absorbing and releasing lithium ions; a negative electrode having a negative electrode current collector on which lithium metal is deposited during charging; a solid electrolyte layer interposed between the positive electrode and the negative electrode so as to be in direct contact with the positive electrode active material layer, the solid electrolyte layer containing a solid electrolyte; A power generating element having an ion-conductive reaction-suppressing layer having lithium ion conductivity and suppressing a reaction between the lithium metal and the solid electrolyte is provided in at least a part of a region of a main surface of the solid electrolyte layer facing the negative electrode current collector, the region being where the positive electrode active material layer faces the negative electrode current collector; a lithium secondary battery, wherein the solid electrolyte layer extends to an end in a planar direction on the positive electrode side of the solid electrolyte layer, and an ion permeation suppression layer made of a material that does not have lithium ion conductivity and suppressing permeation of lithium ions is provided on the end in the planar direction on the negative electrode side of the solid electrolyte layer, and at least a portion of the ion permeation suppression layer overlaps with the ion-conductive reaction suppression layer in a planar view.

2. 2. The lithium secondary battery according to claim 1, wherein the material not having lithium ion conductivity comprises nanoparticles containing a metal oxide or nitride, a resin material, a rubber material, or an S-B-Na based glass frit.

3. a positive electrode including a positive electrode active material layer disposed on a surface of a positive electrode current collector, the positive electrode active material layer containing a positive electrode active material capable of absorbing and releasing lithium ions; a negative electrode having a negative electrode current collector on which lithium metal is deposited during charging; a solid electrolyte layer interposed between the positive electrode and the negative electrode and containing a solid electrolyte; A power generating element having an ion-conductive reaction suppression layer that has lithium ion conductivity and contains nanoparticles containing one or more elements selected from the group consisting of carbon, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, and zinc, or contains one or more lithium-containing compounds selected from the group consisting of lithium halides and composite metal oxides represented by Li-M-O (M is one or more metal elements selected from the group consisting of Mg, Au, Al, Sn, and Zn), and suppresses a reaction between the lithium metal and the solid electrolyte, is provided on at least a part of a region of a main surface of the solid electrolyte layer that faces the negative electrode current collector, where the positive electrode active material layer faces the negative electrode current collector; a solid electrolyte layer extending to an end in a planar direction on the positive electrode side of the solid electrolyte layer, an ion permeation suppression layer that suppresses permeation of lithium ions being provided at the end in the planar direction on the negative electrode side of the solid electrolyte layer, and at least a portion of the ion permeation suppression layer overlaps with the ion-conductive reaction suppression layer in a planar view.

4. 4 . The lithium secondary battery according to claim 1 , wherein at least a portion of an outer circumferential edge of the ion-conductive reaction-suppressing layer is located more inward than an outer circumferential edge of the ion permeation-suppressing layer in a plan view.

5. 4. The lithium secondary battery according to claim 1, wherein at least a part of an outer circumferential edge of the solid electrolyte layer coincides with an outer circumferential edge of the ion permeation suppression layer in a plan view.

6. 4. The lithium secondary battery according to claim 1, wherein at least a part of an inner circumferential edge of the ion permeation suppression layer is located outside an outer circumferential edge of the positive electrode active material layer in a plan view.

7. 4. The lithium secondary battery according to claim 1, wherein a main surface of the solid electrolyte layer facing the negative electrode current collector and a surface of the ion permeation suppression layer facing the negative electrode are disposed flush with each other.

8. 4. The lithium secondary battery according to claim 1, wherein the thickness of the ion permeation suppression layer is half or less of the thickness of the solid electrolyte layer.

9. 4. The lithium secondary battery according to claim 1, wherein the ion permeation suppression layer has a thickness greater at an outer circumferential end at the end in the surface direction on the negative electrode side than at an inner circumferential end at the end in the surface direction on the negative electrode side.

10. 4. The lithium secondary battery according to claim 1, wherein the ion permeation suppression layer is made of a resin material.

11. 4. The lithium secondary battery according to claim 1, wherein the Young's modulus of the solid electrolyte layer and the Young's modulus of the ion permeation suppression layer are substantially the same.

12. 4. The lithium secondary battery according to claim 1, wherein the solid electrolyte layer comprises a fibrous support and is constituted by a self-supporting sheet integrated with the ion permeation suppression layer.