Battery and method for manufacturing the same

Abstract

A battery (100) according to one embodiment of the present invention is provided with: a power storage element (10) which is provided with a positive electrode (11), a negative electrode (13) and a solid electrolyte layer (15) that is arranged between the positive electrode (11) and the negative electrode (13); and an outer package (20) which covers the power storage element (10). At least one of the positive electrode (11), the negative electrode (13) and the solid electrolyte layer (15) contains a solid electrolyte that is represented by formula (1) Li3+a-eE1-bGbDcXd-e; and the internal pressure within a housing space (K) that is enclosed by the outer package (20) is less than 101.3 kPa.

Description

[Technical Field]

[0001] The present invention relates to a battery and a method for manufacturing the same. This application claims priority based on Japanese Patent Application No. 2021-005776, filed in Japan on January 18, 2021, and the contents of that application are incorporated herein by reference. [Background technology]

[0002] In recent years, advancements in electronics technology have been remarkable, leading to the miniaturization, weight reduction, thinning, and increased functionality of portable electronic devices. Consequently, there is a strong demand for smaller, lighter, thinner batteries, and improved reliability for the batteries that power these devices, and all-solid-state batteries, which use solid electrolytes, are attracting attention.

[0003] Two methods for manufacturing all-solid-state batteries are sintering and powder molding. In the sintering method, the negative electrode, solid electrolyte layer, and positive electrode are stacked and then sintered to form an all-solid-state battery. In the powder molding method, the negative electrode, solid electrolyte layer, and positive electrode are stacked and then pressure is applied to form an all-solid-state battery. The materials that can be used for the solid electrolyte layer vary depending on the manufacturing method. Known solid electrolytes include oxide-based solid electrolytes, sulfide-based solid electrolytes, and complex hydride-based solid electrolytes (such as LiBH4).

[0004] Patent Document 1 describes a positive electrode, a negative electrode, and the general formula Li 3-2X M X In 1-Y M' Y L 6-Z L' Z A solid-state electrolyte secondary battery is disclosed having a solid electrolyte composed of a compound represented by the following general formula: In the above general formula, M and M' are metallic elements, and L and L' are halogen elements. Also, X, Y, and Z independently satisfy 0 ≤ X < 1.5, 0 ≤ Y < 1, and 0 ≤ Z ≤ 6. The positive electrode comprises a positive electrode layer containing a positive electrode active material including the element Li and a positive electrode current collector. The negative electrode comprises a negative electrode layer containing a negative electrode active material and a negative electrode current collector.

[0005] Patent Document 2 discloses a solid electrolyte material represented by the following compositional formula (1). Li 6-3Z Y Z X₆···Formula (1) Here, 0<Z<2 is satisfied, and X is Cl or Br. Patent Document 2 also describes a battery in which at least one of a negative electrode and a positive electrode contains the solid electrolyte material.

[0006] Patent Document 3 describes an all-solid battery including an electrode active material layer having a first solid electrolyte material and a second solid electrolyte material. The first solid electrolyte material is a single-phase mixed electron-ion conductor, and is a material that is in contact with an active material and has an anion component different from the anion component of the active material. The second solid electrolyte material is an ionic conductor that is in contact with the first solid electrolyte material, has the same anion component as the first solid electrolyte material, and does not have electron conductivity. The first solid electrolyte material is Li₂ZrS₃.

[0007] However, none of the solid electrolytes described in Patent Documents 1 to 3 have been able to provide sufficient cycle characteristics in some cases. [Prior Art Documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Unexamined Patent Publication No. 2006-244734 [Patent Document 2] International Publication No. WO 2018 / 025582 [Patent Document 3] Japanese Unexamined Patent Publication No. 2013-257992 [Summary of the Invention] [Problem to be Solved by the Invention]

[0009] The present invention has been made in view of the above problem, and an object of the present invention is to provide a battery having high cycle characteristics. [Means for Solving the Problem]

[0010] The inventors of the present invention have conducted intensive studies to solve the above problem. As a result, the inventors found that when an electricity storage element is left standing in the atmosphere, metals such as a current collector contained in the electricity storage element corrode, leading to a decrease in the performance of the electricity storage element. That is, to solve the above problem, the following means are provided.

[0011] (1) The battery according to the first aspect comprises: an electricity storage element including a positive electrode, a negative electrode, and a solid electrolyte layer provided between the positive electrode and the negative electrode; and an exterior body covering the electricity storage element, wherein at least one of the positive electrode, the negative electrode, and the solid electrolyte layer contains a solid electrolyte represented by the following formula (1), Li 3+a-e E 1-b G b D c X d-e ···(1) In formula (1), E is at least one element selected from the group consisting of Al, Sc, Y, Zr, Hf and lanthanoids; G is at least one element selected from the group consisting of Na, K, Rb, Cs, Mg, Ca, Sr, Ba, B, Si, Al, Ti, Cu, Sc, Y, Zr, Nb, Ag, In, Sn, Sb, Hf, Ta, W, Au and Bi; D is at least one group selected from the group consisting of CO3, SO4, BO3, PO4, NO3, SiO3, OH and O2; X is at least one element selected from the group consisting of F, Cl, Br and I; when n=(valence of E)-(valence of G), a=nb, 0≦b<0.5, 0≦c≦5, 0<d≦7.1, 0≦e≦2, and 0<d-e; and an internal pressure in an accommodation space surrounded by the exterior body is less than 101.3 kPa.

[0012] (2) In the battery according to the above aspect, the internal pressure may be lower than an external pressure applied to the exterior body, and a pressure difference between the external pressure and the internal pressure may be 30 kPa or more and 100 kPa or less.

[0013] (3) A battery manufacturing method according to the second embodiment includes an element manufacturing step of sandwiching a solid electrolyte layer between a positive electrode and a negative electrode and press-molding them to produce an energy storage element, A step of preparing an exterior body having an opening, The process of housing the energy storage element inside the outer casing, The process includes the steps of vacuuming the inside of the outer casing to reduce the internal pressure in the containment space to less than 101.3 kPa, and sealing the opening of the outer casing. At least one of the positive electrode, the negative electrode, and the solid electrolyte layer includes a solid electrolyte represented by the following formula (1): Li 3+a-e E 1-b G b D c X d-e ...(1) In equation (1), E is at least one element selected from the group consisting of Al, Sc, Y, Zr, Hf, and lanthanides. G is at least one element selected from the group consisting of Na, K, Rb, Cs, Mg, Ca, Sr, Ba, B, Si, Al, Ti, Cu, Sc, Y, Zr, Nb, Ag, In, Sn, Sb, Hf, Ta, W, Au, and Bi. D is at least one selected from the group consisting of CO3, SO4, BO3, PO4, NO3, SiO3, OH, and O2. X is at least one element selected from the group consisting of F, Cl, Br, and I, and when n = (valence of E) - (valence of G), a = nb, 0 ≤ b < 0.5, 0 ≤ c ≤ 5, 0 <d≦7.1、0≦e≦2、0<d-eである。 [Effects of the Invention]

[0014] The battery according to the above embodiment has excellent cycle characteristics. [Brief explanation of the drawing]

[0015] [Figure 1] This is a perspective view of the all-solid-state battery according to this embodiment. [Figure 2] This is a cross-sectional view of the all-solid-state battery according to this embodiment. [Modes for carrying out the invention]

[0016] The present embodiment will be described in detail below with reference to the drawings as appropriate. The drawings used in the following description may be enlarged for convenience to clearly illustrate the features of the present invention, and the dimensional ratios of each component may differ from those in reality. The materials, dimensions, etc., exemplified in the following description are examples only, and the present invention is not limited to them. It can be implemented with appropriate modifications without altering its essence.

[0017] Figure 1 is a perspective view of the all-solid-state battery 100 according to this embodiment. The all-solid-state battery 100 shown in Figure 1 comprises an energy storage element 10 and an outer casing 20. The energy storage element 10 is housed in a housing space K within the outer casing 20. For ease of understanding, Figure 1 illustrates the state immediately before the energy storage element 10 is housed in the outer casing 20. The energy storage element 10 has external terminals 12 and 14 that are electrically connected to the outside.

[0018] The outer casing 20 has, for example, a metal foil 22 and a resin layer 24 laminated on both sides of the metal foil 22 (see Figure 2). The outer casing 20 is a metal laminate film in which the metal foil 22 is coated on both sides with a polymer film (resin layer 24). The metal foil 22 is, for example, aluminum foil. The resin layer 24 is, for example, a polymer film such as polypropylene. The resin layer 24 may be the same on the inside and the outside, or it may be different. For example, a polymer with a high melting point, such as polyethylene terephthalate (PET) or polyamide (PA), can be used as the outer resin layer, and materials with high heat resistance, oxidation resistance, reduction resistance, corrosion resistance, and weather resistance can be used as the inner resin layer, such as polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), tetrafluoroethylene resin (PTFE or TFE), fluoroethylene propylene resin (FEP), trifluoroethylene chloride resin (CTFE), vinylidene fluoride resin, polyimide, or perfluorinated alkoxy resin (PFA). From the viewpoint of further improving heat resistance, oxidation resistance, reduction resistance, corrosion resistance, and weather resistance, a resin layer obtained by molding two or more types of resins in a matrix or a multilayer resin layer with two or more layers may be used.

[0019] The internal pressure of the containment space K surrounded by the outer casing 20 is less than 101.3 kPa. The internal pressure of the containment space K is less than atmospheric pressure. Internal pressure refers to the pressure inside the containment space K. The internal pressure of the outer casing 20 is lower than the external pressure acting on the outer casing 20. The external pressure acting on the outer casing 20 is, for example, atmospheric pressure. The difference between the external pressure acting on the outer casing 20 and the internal pressure is, for example, 30 kPa or more and 100 kPa or less, preferably 50 kPa or more and 100 kPa or less. The internal pressure of the outer casing 20 is, for example, 30 kPa or less lower than the external pressure, preferably 50 kPa or less lower than the external pressure, and 100 kPa or more lower than the external pressure.

[0020] This method suppresses the formation of spaces between the positive electrode current collector 11A and the positive electrode active material layer 11B, or between the negative electrode current collector 13A and the negative electrode active material 13B. Halogenated gases generated by the decomposition of the solid electrolyte tend to accumulate in these spaces. By suppressing the formation of spaces between these layers, contact between the halogenated gases and the current collectors in these spaces can be suppressed. This suppresses a localized decrease in current collection function and enables a uniform electrochemical reaction. As a result, the cycle characteristics (maintenance rate) of the all-solid-state battery 100 are improved.

[0021] At the same time, suppressing the formation of the aforementioned space improves the adhesion between the positive electrode current collector 11A and the positive electrode active material layer 11B, or between the negative electrode current collector 13A and the negative electrode active material 13B. It also suppresses the occurrence of uneven current flow that bypasses the aforementioned space. As a result, the electrochemical reaction becomes more uniform, and the cycle characteristics (maintenance rate) of the all-solid-state battery 100 are improved.

[0022] The internal pressure inside the outer casing 20 can be measured by housing the all-solid-state battery 100 in a vacuum container and gradually lowering the pressure inside the vacuum container. When the pressure inside the vacuum container drops below a certain value, the internal pressure of the outer casing 20 becomes greater than the external pressure, and the outer casing 20 begins to expand. The pressure at which the outer casing 20 begins to expand is defined as the internal pressure inside the outer casing 20.

[0023] By creating a vacuum inside the outer casing 20 and reducing the amount of gas and moisture present inside the casing 20, the probability of the solid electrolyte reacting with the gas and moisture is reduced, thereby suppressing the generation of halogenated gases. Halogenated gases cause corrosion in the metal parts of the energy storage element 10 (such as the positive electrode current collector 11A and the negative electrode current collector 13A, described later), which is one of the causes of reduced current collection function. In other words, by creating a vacuum inside the outer casing 20 and reducing the amount of gas and moisture present inside the casing 20, corrosion of the positive electrode current collector 11A or the negative electrode current collector 13A in the all-solid-state battery 100 is suppressed, and the cycle characteristics (maintenance rate) of the all-solid-state battery 100 are improved.

[0024] Furthermore, creating a vacuum inside the outer casing 20 reduces the amount of gas and moisture present inside the casing 20, thereby reducing side reactions between the solid electrolyte and the gas and moisture. These side reactions of the solid electrolyte are reactions associated with the decomposition of the solid electrolyte, and consume a portion of the energy used for charging or discharging. Suppressing these side reactions of the solid electrolyte improves the electrochemical stability of the solid electrolyte. In addition, the use of a portion of the energy used for charging or discharging in the decomposition of the solid electrolyte is suppressed, improving the cycle characteristics (maintenance rate) of the all-solid-state battery 100.

[0025] The gas contained within the outer casing 20 is, for example, at least one selected from argon, nitrogen, oxygen, carbon dioxide, neon, helium, and hydrogen. By controlling the gas contained within the outer casing 20, the generation of halogenated gases can be further suppressed.

[0026] Figure 2 is a cross-sectional view of an all-solid-state battery 100 according to this embodiment. The all-solid-state battery 100 has a positive electrode 11, a negative electrode 13, a solid electrolyte layer 15, external terminals 12 and 14, and a housing space K. The positive electrode 11 has a positive electrode current collector 11A and a positive electrode active material layer 11B. The negative electrode 13 has a negative electrode current collector 13A and a negative electrode active material layer 13B. The solid electrolyte layer 15 is, for example, located between the positive electrode active material layer 11B and the negative electrode active material layer 13B.

[0027] The all-solid-state battery 100 is charged or discharged by the exchange of electrons via the positive electrode current collector 11A and the negative electrode current collector 13A, and by the exchange of lithium ions via the solid electrolyte layer 15. The all-solid-state battery 100 may be a laminate in which the positive electrode 11, the negative electrode 13, and the solid electrolyte layer 15 are stacked, or it may be a winding of these components. The all-solid-state battery 100 is used, for example, in laminate batteries, prismatic batteries, cylindrical batteries, coin-type batteries, button-type batteries, etc.

[0028] The amount of water contained in the energy storage element 10 is preferably 0.01 mg / g or more and 1 mg / g or less per unit mass, and more preferably 0.01 mg / g or more and 0.5 mg / g or less. The amount of water contained in the energy storage element 10 per unit mass can be determined by dividing the weight of the water contained in the energy storage element 10 by the weight of the energy storage element 10. The amount of water contained in the energy storage element 10 can be measured, for example, using the Karl Fischer method.

[0029] When the amount of water contained in the energy storage element 10 is between 0.01 mg / g and 1 mg / g per unit mass, the particles constituting the energy storage element 10 flow during pressure molding, which can suppress the occurrence of cracks in the energy storage element 10. Suppressing cracks within the energy storage element 10 improves the cycle characteristics (maintenance rate) of the all-solid-state battery 100. This is because it makes it difficult for current and lithium ions to bypass cracks, thus suppressing localized non-uniformity in the charging and discharging reactions.

[0030] If the energy storage element 10 contains a large amount of moisture, the jig and the energy storage element 10 may adhere tightly during pressure molding. As a result, cracks are more likely to occur when removing the energy storage element 10 from the jig. As described above, cracks within the energy storage element 10 can cause locally uneven charging and discharging reactions.

[0031] Conversely, if the amount of moisture contained in the energy storage element 10 is too low, the particles constituting the energy storage element 10 will not flow easily during pressure molding, resulting in uneven adhesion between particles and making the energy storage element 10 more prone to cracking. As described above, cracks within the energy storage element 10 cause locally uneven charge / discharge reactions, leading to a decrease in the cycle characteristics (maintenance rate) of the all-solid-state battery 100.

[0032] The moisture content in the containment space K is, for example, 1100 ppmv or less. Preferably, the moisture content in the containment space K is, for example, 0.5 ppmv or more and 600 ppmv or less. If the moisture content in the containment space K is within the above range, the generation of halogenated gas due to the reaction between the solid electrolyte and moisture can be suppressed. Halogenated gas causes corrosion in the metal parts of the energy storage element 10 (current collector, conductive additive, storage container, etc.), which is one of the causes of reduced current collection function. Suppressing the generation of halogenated gas can suppress localized non-uniformity of the electrochemical reaction, and the cycle characteristics (maintenance rate) of the all-solid-state battery 100 can be further improved.

[0033] "Solid electrolyte layer" The solid electrolyte layer 15 contains a solid electrolyte. The solid electrolyte layer 15 contains, for example, a solid electrolyte represented by the following formula (1). Li 3+a-e E 1-b G b D c X d-e ...(1)

[0034] In formula (1) above, E is a trivalent or tetravalent element. E is, for example, at least one element selected from the group consisting of Al, Sc, Y, Zr, Hf, and lanthanides. The lanthanides are La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. When the solid electrolyte contains the element E, the potential window of the solid electrolyte is broadened. E preferably contains Sc or Zr, and is particularly preferably Zr. When E contains Sc or Zr, the ionic conductivity of the solid electrolyte is increased.

[0035] In the solid electrolyte represented by formula (1) above, G is an element that may be included as needed. G is at least one element selected from the group consisting of Na, K, Rb, Cs, Mg, Ca, Sr, Ba, B, Si, Al, Ti, Cu, Sc, Y, Zr, Nb, Ag, In, Sn, Sb, Hf, Ta, W, Au, and Bi. When the solid electrolyte contains the element G, the amount of lithium ions, which are carrier ions, increases or decreases, and the ionic conductivity increases.

[0036] In formula (1), G may be a monovalent element selected from Na, K, Rb, Cs, and Ag. When G is a monovalent element, the solid electrolyte has high ionic conductivity and a wide potential window on the reducing side. Na and / or Cs are particularly preferred for G.

[0037] In formula (1), G may be a divalent element selected from Mg, Ca, Ba, Sr, Cu, and Sn. When G is a divalent element, the number of carrier ions increases, resulting in a solid electrolyte with high ionic conductivity and a wide potential window on the reducing side. Mg and / or Ca are particularly preferred for G.

[0038] In formula (1), G may be a trivalent element selected from Al, Y, In, Au, and Bi. When G is a trivalent element, the number of carrier ions increases, resulting in a solid electrolyte with high ionic conductivity. G is particularly preferably one selected from the group consisting of In, Au, and Bi.

[0039] In formula (1), G may be one of the tetravalent elements listed above: Zr, Hf, or Sn. When G is a tetravalent element, it results in a solid electrolyte with high ionic conductivity. G is particularly preferably Hf and / or Zr.

[0040] In formula (1), G may be a pentavalent element selected from Nb, Sb, and Ta. When G is a pentavalent element, holes are formed, making it easier for carrier ions to move, resulting in a solid electrolyte with high ionic conductivity. G is particularly preferably Sb and / or Ta.

[0041] In equation (1), G may be W, which is a hexavalent element from the above list. When G is a hexavalent element, it becomes a solid electrolyte with high ionic conductivity.

[0042] In formula (1), D is included as needed. D is at least one selected from the group consisting of CO3, SO4, BO3, PO4, NO3, SiO3, OH, and O2. When the solid electrolyte contains D, the potential window on the reducing side of the solid electrolyte becomes wider. D is preferably at least one selected from the group consisting of SO4, CO3, PO4, and O2, and is particularly preferably SO4. If the covalent bond between D and E is strong, the ionic bond between E and X will also become stronger. For this reason, it is presumed that E in the compound is less likely to be reduced, resulting in a compound with a wide potential window on the reducing side.

[0043] In formula (1), X is an essential element. X is at least one element selected from the group consisting of F, Cl, Br, and I. X has a large ionic radius per valence. The presence of X in the solid electrolyte increases the conductivity of lithium ions within the solid electrolyte. To increase the ionic conductivity of the solid electrolyte, it is preferable that X contains Cl. To improve the balance between oxidation resistance and reduction resistance of the solid electrolyte, it is preferable that X contains F. To enhance the reduction resistance of the solid electrolyte, it is preferable that X contains I.

[0044] In equation (1), when n = (valence of E) - (valence of G), a = nb. In equation (1), when b = 0 (i.e., G is not included), a = 0. In equation (1), a is the above value determined according to the valence of G.

[0045] In formula (1), b is between 0 and less than 0.5. The solid electrolyte represented by formula (1) contains E as an essential element, but does not necessarily contain G. If b is 0.1 or greater, the effects obtained by including G in the solid electrolyte can be fully obtained. Furthermore, from the viewpoint of suppressing the decrease in the ionic conductivity of the solid electrolyte, b is preferably less than 0.5. It is more preferable that b is 0.45 or less.

[0046] In formula (1), c is 0 or more and 5 or less. Therefore, D does not need to be contained in the solid electrolyte. When D is contained in the compound represented by formula (1), c is preferably 0.1 or more. When c is 0.1 or more, the effect of widening the potential window on the reduction side of the solid electrolyte obtained by containing D can be sufficiently obtained. If the content of D is too high, there is a concern that the ionic conductivity of the solid electrolyte will decrease due to the narrowing of the space through which carrier ions move. From the viewpoint of suppressing such a decrease, c is 5 or less, and preferably 2.5 or less.

[0047] In formula (1), d is greater than 0 and 7.1 or less. When d is 7.1 or less, the binding force to carrier ions caused by an excessively high content of X is suppressed, and a decrease in the ionic conductivity of the solid electrolyte can be suppressed, which is preferable.

[0048] In formula (1), e is 0 or more and 2 or less. In addition, 0 < d-e is satisfied. When formula (1) satisfies 0 ≦ e ≦ 2 and 0 < d-e, the Li content and X content contained in the compound represented by formula (1) become appropriate, and the ionic conductivity of the solid electrolyte increases.

[0049] In order to obtain a solid electrolyte having a wide potential window and high ionic conductivity, in the solid electrolyte represented by formula (1), it is preferable that E is Zr and X is Cl. Specifically, as the compound represented by formula (1), Li₂ZrCl₆, Li₂ZrCl₄SO₄, or Li₂ZrOCl₄ are preferable as solid electrolytes having a good balance between ionic conductivity and potential window.

[0050] The solid electrolyte layer 15 may contain other substances together with the solid electrolyte represented by formula (1). Examples of the other substances include Li₂O, Li₂CO₃, LiX (where X is at least one selected from the group consisting of F, Cl, Br and I), Sc₂O₃, ScX₃ (where X is at least one element selected from the group consisting of F, Cl, Br and I), GO n(G is at least one element selected from the group consisting of Na, K, Rb, Cs, Mg, Ca, Sr, Ba, B, Si, Al, Ti, Cu, Y, Zr, Nb, Ag, In, Sn, Sb, Hf, Ta, W, Au, and Bi. When the valence of G is m, n = m / 2.) It is at least one compound selected from the group consisting of (G is at least one element selected from the group consisting of Na, K, Rb, Cs, Mg, Ca, Sr, Ba, B, Si, Al, Ti, Cu, Y, Zr, Nb, Ag, In, Sn, Sb, Hf, Ta, W, Au, and Bi. When the valence of G is m, n = m / 2.)

[0051] When the solid electrolyte layer 15 contains the above-mentioned other substances, the ionic conductivity of the solid electrolyte layer 15 increases. The detailed reason for this is unknown, but it is thought to be as follows: In the solid electrolyte layer 15, the above-mentioned other substances have the function of facilitating ionic connections between particles made up of the solid electrolyte represented by equation (1). As a result, the grain boundary resistance between particles of the solid electrolyte represented by equation (1) decreases, and it is presumed that the ionic conductivity of the solid electrolyte layer 15 as a whole increases.

[0052] The content of other substances in the solid electrolyte layer 15 is, for example, between 0.1% by mass and 1.0% by mass, from the viewpoint of obtaining the effect of reducing grain boundary resistance between particles. Furthermore, if the content of other substances exceeds 1.0% by mass, cracks are more likely to occur in the solid electrolyte layer 15, and the ionic connection between particles is hindered.

[0053] The solid electrolyte layer 15 may contain a binder. The solid electrolyte layer 15 may contain, for example, fluororesins such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), cellulose, imide resins such as styrene-butadiene rubber, ethylene-propylene rubber, polyimide resin, and polyamide-imide resin, and ion-conductive polymers. The ion-conductive polymer is, for example, a compound obtained by compounding a monomer of a polymer compound (polyether polymer compounds such as polyethylene oxide and polypropylene oxide, polyphosphozene, etc.) with a lithium salt such as LiCl4, LiBF4, LiPF6, LiTFSI, or an alkali metal salt mainly composed of lithium. The binder content is preferably 0.1% to 30% by volume of the total solid electrolyte layer 15. The binder helps maintain good bonding between the solid electrolytes in the solid electrolyte layer 15, prevents the occurrence of cracks between the solid electrolytes, and suppresses a decrease in ion conductivity and an increase in grain boundary resistance.

[0054] "Positive electrode" As shown in Figure 2, the positive electrode 11 includes, for example, a positive electrode current collector 11A and a positive electrode active material layer 11B containing positive electrode active material.

[0055] (Positive electrode current collector) The positive electrode current collector 11A preferably has high conductivity. For example, metals such as silver, palladium, gold, platinum, aluminum, copper, nickel, titanium, stainless steel and their alloys, or conductive resins can be used. The positive electrode current collector 11A may be in the form of powder, foil, punched, or expanded. From the viewpoint of not degrading the current collecting function of the positive electrode current collector 11A, it is preferable to dehydrate it by heating and vacuum drying in a glove box with circulating argon gas, and then store the positive electrode current collector 11A in a glass bottle or aluminum laminate bag. The dew point inside the glove box should be, for example, -30°C or lower and -90°C or higher.

[0056] (Cathode active material layer) The positive electrode active material layer 11B is formed on one or both sides of the positive electrode current collector 11A. The positive electrode active material layer 11B contains positive electrode active material. The positive electrode active material layer 11B may also contain, for example, a solid electrolyte represented by the above formula (1). The positive electrode active material layer 11B may also contain a conductive additive and a binder.

[0057] The positive electrode mixture used in the positive electrode active material layer 11B is prepared by mixing it in a glove box with circulating argon gas using an agate mortar and pestle, a pot mill, a blender, a hybrid mixer, etc. From the viewpoint of ensuring good pressure molding of the energy storage element 10, the dew point inside the glove box is preferably -30°C or lower and -90°C or higher. The oxygen concentration inside the glove box is, for example, 1 ppm or lower.

[0058] (Cathode active material) The positive electrode active material contained in the positive electrode active material layer 11B is, for example, a lithium-containing transition metal oxide, a transition metal fluoride, a polyanion, a transition metal sulfide, a transition metal oxyfluoride, a transition metal oxysulfide, or a transition metal oxynitride.

[0059] The positive electrode active material is not particularly limited as long as it can reversibly release and intercalate lithium ions, and desorption and insertion lithium ions. Any positive electrode active material used in known lithium-ion secondary batteries can be used. Examples of positive electrode active materials include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese spinel (LiMn2O4), and LiNi (general formula: LiNi). x Co y Mn z M a Composite metal oxides represented by O2 (x+y+z+a=1, 0≦x≦1, 0≦y≦1, 0≦z≦1, 0≦a≦1, M is one or more elements selected from Al, Mg, Nb, Ti, Cu, Zn, Cr), lithium vanadium compounds (LiV2O5, Li3V2(PO4)3, LiVOPO4), olivine-type LiMPO4 (where M is one or more elements selected from Co, Ni, Mn, Fe, Mg, V, Nb, Ti, Al, Zr), lithium titanate (Li4Ti5O 12), LiNi x Co y Al z O₂ (0.9<x+y+z<1.1) and other composite metal oxides. From the viewpoint of achieving favorable pressure molding, it is preferable that the positive electrode active material used in the positive electrode active material layer 11B is dehydrated by heating vacuum drying or the like in a glove box with circulating argon gas, and then stored in a glass bottle, an aluminum laminate bag or the like. The dew point in the glove box is preferably -30°C or lower and -90°C or higher.

[0060] In addition, if a negative electrode active material doped with metallic lithium or lithium ions is disposed on the negative electrode in advance, a positive electrode active material that does not contain lithium can also be used by starting the battery from discharge. Examples of such positive electrode active materials include lithium-free metal oxides (such as MnO₂ and V₂O₅), lithium-free metal sulfides (such as MoS₂), and lithium-free fluorides (such as FeF₃ and VF₃).

[0061] "Negative Electrode" As shown in Figure 2, the negative electrode 13 includes, for example, a negative electrode current collector 13A and a negative electrode active material layer 13B containing a negative electrode active material.

[0062] (Negative Electrode Current Collector) The negative electrode current collector 13A preferably has high electrical conductivity. For example, it is preferable to use metals such as silver, palladium, gold, platinum, aluminum, copper, nickel, stainless steel, iron, alloys thereof, or conductive resins. The negative electrode current collector 13A may be in any form of powder, foil, punching metal, or expanded metal. From the viewpoint of not reducing the current collecting function of the negative electrode current collector 13A, it is preferable that the negative electrode current collector 13A is dehydrated by heating vacuum drying or the like in a glove box with circulating argon gas, and then stored in a glass bottle, an aluminum laminate bag or the like. The dew point in the glove box is, for example, -30°C or lower and -90°C or higher.

[0063] (Negative Electrode Active Material Layer) The negative electrode active material layer 13B is formed on one or both sides of the negative electrode current collector 13A. The negative electrode active material layer 13B contains a negative electrode active material. The negative electrode active material layer 13B may, for example, contain the solid electrolyte represented by the above formula (1). Further, the negative electrode active material layer 13B may contain a conductive aid and a binder.

[0064] The negative electrode mixture used for the negative electrode active material layer 13B is prepared by mixing, for example, in a glove box with circulated argon gas using an agate mortar, pot mill, blender, hybrid mixer, or the like. From the viewpoint of favorably performing pressure molding of the electricity storage element 10, the dew point in the glove box is preferably -30°C or lower and -90°C or higher. The oxygen concentration in the glove box is, for example, 1 ppm or less.

[0065] (Negative Electrode Active Material) The negative electrode active material contained in the negative electrode active material layer 13B only needs to be a compound capable of inserting and extracting mobile ions, and negative electrode active materials used in known lithium ion secondary batteries can be used. Examples of the negative electrode active material include simple alkali metals, alkali metal alloys, graphite (natural graphite, artificial graphite), carbon nanotubes, non-graphitizable carbon, graphitizable carbon, carbon materials such as low-temperature calcined carbon, metals capable of combining with metals such as alkali metals including aluminum, silicon, tin, germanium and alloys thereof, SiO x (0 < x < 2), oxides such as iron oxide, titanium oxide, and tin dioxide, lithium titanate (Li4Ti5O 12 ) and other lithium metal oxides. From the viewpoint of favorably performing pressure molding, the negative electrode active material used for the negative electrode active material layer 13B is preferably dehydrated by heating vacuum drying or the like in a glove box with circulated argon gas, and then stored using a glass bottle, an aluminum laminate bag, or the like. The dew point in the glove box is preferably -30°C or lower and -90°C or higher.

[0066] (Conductive Aid) The conductive additive is not particularly limited as long as it improves the electronic conductivity of the positive electrode active material layer 11B and the negative electrode active material layer 13B, and known conductive additives can be used. Examples of conductive additives include carbon-based materials such as graphite, carbon black, graphene, and carbon nanotubes, metals such as gold, platinum, silver, palladium, aluminum, copper, nickel, stainless steel, and iron, conductive oxides such as ITO, or mixtures thereof. The conductive additive may be in the form of a powder or fibers. Furthermore, from the viewpoint of not degrading the current-collecting function of the conductive additive, it is preferable to dehydrate it by heating and vacuum drying in a glove box with circulating argon gas, and then store the conductive additive in a glass bottle or aluminum laminate bag. The dew point inside the glove box is preferably -30°C or lower and -90°C or higher.

[0067] (Binding agent) The binder joins the positive electrode current collector 11A to the positive electrode active material layer 11B, the negative electrode current collector 13A to the negative electrode active material layer 13B, the positive electrode active material layer 11B, and the negative electrode active material layer 13B to the solid electrolyte layer 15, the various materials constituting the positive electrode active material layer 11B, and the various materials constituting the negative electrode active material layer 13B.

[0068] The binder is preferably used within a range that does not impair the functions of the positive electrode active material layer 11B and the negative electrode active material layer 13B. The binder can be any material capable of the above-mentioned bonding, such as polyvinylidene fluoride (PVDF) or fluororesins such as polytetrafluoroethylene (PTFE). Furthermore, in addition to the above, other binders such as cellulose, styrene-butadiene rubber, ethylene-propylene rubber, polyimide resin, and polyamide-imide resin may also be used. Alternatively, conductive polymers with electronic conductivity or ionic conductive polymers may be used as binders. Examples of conductive polymers with electronic conductivity include polyacetylene. In this case, since the binder also functions as conductive additive particles, it is not necessary to add a conductive additive. Examples of ionic conductive polymers that conduct lithium ions include monomers of polymer compounds (polyether-based polymer compounds such as polyethylene oxide and polypropylene oxide, polyphosphonates, etc.) and LiClO4, LiBF4, LiPF 6、 Examples include composites of lithium salts such as LiTFSI and LiFSI, or alkali metal salts mainly composed of lithium. Polymerization initiators used in the composites include, for example, photopolymerization initiators or thermal polymerization initiators compatible with the above monomers. Required properties for the binder include oxidation / reduction resistance and good adhesion.

[0069] The binder content in the positive electrode active material layer 11B is not particularly limited, but it is preferable that it be 0.5 to 30 volume percent from the viewpoint of lowering the resistance of the positive electrode active material layer 11B. Furthermore, from the viewpoint of improving energy density, it is preferable that the binder content in the positive electrode active material layer 11B be 0 volume percent.

[0070] The binder content in the negative electrode active material layer 13B is not particularly limited, but it is preferable that it be 0.5 to 30 volume percent from the viewpoint of lowering the resistance of the negative electrode active material layer 13B. Furthermore, from the viewpoint of improving energy density, it is preferable that the binder content in the negative electrode active material layer 13B be 0 volume percent.

[0071] At least one of the positive electrode active material layer 11B, the negative electrode active material layer 13B, and the solid electrolyte layer 15 may be mixed with a non-aqueous electrolyte, an ionic liquid, or a gel electrolyte for the purpose of improving the rate characteristics, which are one of the battery characteristics.

[0072] "Method for manufacturing solid electrolytes" A method for producing a solid electrolyte represented by formula (1) will be described. The solid electrolyte is obtained by mixing and reacting raw material powders in a predetermined molar ratio to achieve the desired composition. The reaction method is not limited, but methods such as mechanochemical milling, sintering, melting, liquid phase, and solid phase can be used.

[0073] Solid electrolytes can be manufactured, for example, by mechanochemical milling. First, a planetary ball mill apparatus is prepared. A planetary ball mill apparatus is a device that places media (hard balls to promote grinding or mechanochemical reactions) and materials into a dedicated container, rotates and revolves, and grinds the materials or causes mechanochemical reactions between the materials.

[0074] The solid electrolyte is prepared, for example, in a glove box with circulating argon gas. From the viewpoint of stably synthesizing the target compound, the dew point inside the glove box is preferably -20°C or lower and -90°C or higher, and more preferably -30°C or lower and -80°C or higher. The oxygen concentration inside the glove box is, for example, 1 ppm or lower.

[0075] Next, the raw materials are prepared in a zirconia container in a predetermined molar ratio to achieve the desired composition, and the container is sealed with a zirconia lid. A predetermined amount of zirconia balls are placed in the zirconia container. The raw materials may be in powder or liquid form. For example, titanium chloride (TiCl4) and tin chloride (SnCl4) are liquids at room temperature. Then, a mechanochemical reaction is induced by performing mechanochemical milling for a predetermined time at predetermined rotation and revolution speeds. By this method, a powdered solid electrolyte consisting of a compound having the desired composition can be obtained.

[0076] "Manufacturing method for all-solid-state batteries" Next, a method for manufacturing the all-solid-state battery according to this embodiment will be described. The all-solid-state battery according to this embodiment is manufactured, for example, using a powder molding method. The powder molding method is also performed in a glove box. The dew point inside the glove box is preferably, for example, -20°C or lower and -90°C or higher. The oxygen concentration inside the glove box is, for example, 1 ppm or lower.

[0077] (Powder molding method) First, a resin holder with a through hole in the center, a lower punch, and an upper punch are prepared. To improve moldability, a metal holder made of die steel may be used instead of the resin holder. The diameter of the through hole in the resin holder is, for example, 10 mm, and the diameters of the lower and upper punches are, for example, 9.99 mm. The lower punch is inserted from below the through hole in the resin holder, and powdered solid electrolyte is put in from the opening side of the resin holder. Next, the upper punch is inserted on top of the powdered solid electrolyte that has been put in, and the machine is placed on a press and pressed. The pressing pressure is, for example, 373 MPa. The powdered solid electrolyte is pressed by the upper and lower punches inside the resin holder to form a solid electrolyte layer 15.

[0078] Next, the upper punch is temporarily removed, and the material for the positive electrode active material layer is placed on the upper punch side of the solid electrolyte layer 15. Then, the upper punch is reinserted and pressed. The pressing pressure is, for example, 373 MPa. The material for the positive electrode active material layer becomes the positive electrode active material layer 11B through pressing.

[0079] Next, the lower punch is temporarily removed, and the material for the negative electrode active material layer is placed on the lower punch side of the solid electrolyte layer 15. For example, the sample is turned upside down, and the material for the negative electrode active material layer is placed on the solid electrolyte layer 15 so that it faces the positive electrode active material layer 11B. After that, the lower punch is inserted again and pressed. The pressing pressure is, for example, 373 MPa. The material for the negative electrode active material layer becomes the negative electrode active material layer 13B after pressing.

[0080] Next, the upper punch is removed, and the positive electrode current collector 11A and the upper punch are inserted on top of the positive electrode active material layer 11B in that order. The lower punch is also removed, and the negative electrode current collector 13A and the lower punch are inserted on top of the negative electrode active material layer 13B in that order. The positive electrode current collector 11A and the negative electrode current collector 13A are, for example, 10 mm diameter aluminum foil or copper foil. After the above procedure, the energy storage element 10 of this embodiment is obtained, consisting of the positive electrode current collector 11A / positive electrode active material layer 11B / solid electrolyte layer 15 / negative electrode active material layer 13B / negative electrode current collector 13A.

[0081] The energy storage element 10 may, if necessary, be made of a stainless steel disc and a bakelite disc, each having four screw holes, and may be stacked in the order of stainless steel disc / bakelite disc / upper punch / energy storage element 10 / lower punch / bakelite disc / stainless steel disc, with the four screws tightened. With this configuration, the bonding between the upper punch and the positive electrode current collector 11A, between the positive electrode current collector 11A and the positive electrode active material 11B, between the lower punch and the negative electrode current collector 13A, and between the negative electrode current collector 13A and the negative electrode active material 13B is improved. The energy storage element 10 may also be a similar mechanism with a shape-retaining function.

[0082] Next, screws are inserted into the screw holes provided on the sides of the upper and lower punches, and then inserted into the casing to which the external terminals 12 and 14 are attached. The screws attached to the sides of the upper and lower punches are then connected to the external terminals 12 and 14 with lead wires or the like. After that, the casing is housed inside the casing 20. The casing 20 improves the weather resistance of the all-solid-state battery 100.

[0083] Next, all but one opening of the outer casing 20 is heat-sealed. Then, while vacuuming the inside of the outer casing 20, the remaining opening is heat-sealed. Specifically, the internal pressure in the containment space K of the outer casing 20 is kept below 101.3 kPa, and the opening of the outer casing 20 is sealed while maintaining this state. By heat-sealing the inside of the outer casing 20 while vacuuming, it is possible to seal it while suppressing the formation of a space between the positive electrode current collector 11A and the positive electrode active material layer 11B, or between the negative electrode current collector 13A and the negative electrode active material 13B. In addition, the outer casing 20 can be sealed with a low level of gas and moisture present in the containment space K.

[0084] The manufacturing method for the energy storage element 10 described above was explained using powder molding as an example, but it may also be manufactured using a sheet molding method containing resin. The sheet molding method is also carried out inside the glove box. The glove box is preferably manufactured in an environment where the dew point is between -20°C and -90°C.

[0085] For example, first, a solid electrolyte paste containing a powdered solid electrolyte is prepared. The prepared solid electrolyte paste is applied to a PET film or a fluororesin film, dried, pre-molded, and peeled off to create a solid electrolyte layer 15. A positive electrode 11 is then prepared by applying a positive electrode active material paste containing a positive electrode active material onto a positive electrode current collector 11A, drying, and pre-molding to form a positive electrode active material layer 11B. A negative electrode 13 is then prepared by applying a paste containing a negative electrode active material onto a negative electrode current collector 13A, drying, and pre-molding to form a negative electrode active material layer 13B. The positive electrode 11, negative electrode 13, and solid electrolyte layer 15 can be punched out to the required size and shape.

[0086] Next, the solid electrolyte layer 15 is sandwiched between the positive electrode 11 and the negative electrode 13 so that the positive electrode active material layer 11B and the negative electrode active material layer 13B face each other, and the whole is pressed and bonded together. Through these steps, the energy storage element 10 of this embodiment is obtained.

[0087] In this embodiment, the all-solid-state battery 100 has a difference between the external pressure and the internal pressure applied to the outer casing 20, which suppresses the deterioration of the current collection function due to corrosion of the positive electrode current collector 11A or the negative electrode current collector 13AA by halogenated gas, enabling a uniform electrochemical reaction and improving the cycle characteristics (maintenance rate) of the all-solid-state battery 100.

[0088] Although embodiments of the present invention have been described in detail above with reference to the drawings, the configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications to the configurations are possible without departing from the requirements of the present invention. [Examples]

[0089] (Example 1) -Synthesis of Solid Electrolytes- Solid electrolyte synthesis, positive electrode active material layer mixing, negative electrode active material layer mixing, and all-solid-state battery fabrication were carried out in a glove box under a dew point of -90°C, oxygen concentration of 1 ppm, and atmospheric pressure environment with circulating argon gas. First, Li2SO4 and ZrCl4 were weighed as raw material powders in a molar ratio of 1:1. Next, the weighed raw material powders were placed in a Zr container along with Zr balls with a diameter of 5 mm, and mechanochemical milling was performed using a planetary ball mill. The process involved mixing at a rotation speed of 500 rpm for 50 hours, followed by sieving through a 200 μm mesh. This yielded Li2ZrSO4Cl4 powder as the solid electrolyte.

[0090] -Synthesis of positive electrode mixture- Next, the cathode mixture was weighed and mixed in a glove box with a dew point of -85°C and an oxygen concentration of 1 ppm, circulating argon gas. The lithium cobalt oxide (LiCoO2):solid electrolyte (Li2ZrSO4Cl4):carbon black was weighed to a ratio of 77:18:5 parts by weight, and mixed in an agate mortar for 5 minutes to obtain the cathode mixture.

[0091] - Preparation of the negative electrode mixture - Next, the negative electrode mixture was weighed and mixed in a glove box with circulating argon gas, a dew point of -85°C, and an oxygen concentration of 1 ppm. (Lithium titanate (Li4Ti5O)) 12 The solid electrolyte (Li2ZrSO4Cl4) and carbon black were weighed in a ratio of 72:22:6 parts by weight and mixed in an agate mortar for 5 minutes to obtain the negative electrode mixture.

[0092] -Molding process- Using the above-mentioned solid electrolyte, positive electrode mixture, and negative electrode mixture, a power storage element consisting of a positive electrode current collector, a positive electrode mixture layer, an electrolyte layer, a negative electrode mixture layer, and a negative electrode current collector was fabricated by powder molding. The power storage element was fabricated in a glove box with a dew point of -90°C and an oxygen concentration of 1 ppm, with argon gas circulating.

[0093] First, a resin holder with a 10mm diameter through-hole in the center, a 9.99mm diameter lower punch made of SKD11 material, and an upper punch were prepared. The lower punch was inserted from below the through-hole in the resin holder, and 110mg of solid electrolyte was added from the opening side of the resin holder. Next, the upper punch was inserted on top of the solid electrolyte. This first unit was placed on a press machine and pressed at a pressure of 373MPa to form the solid electrolyte layer. The first unit was removed from the press machine, and the upper punch was removed.

[0094] Next, 12 mg of positive electrode compound was added to the solid electrolyte layer (upper punch side) from the opening side of the resin holder, and the upper punch was inserted on top of it. This second unit was placed in a press machine and molded at a pressure of 373 MPa. Then the second unit was removed, inverted, and the lower punch was removed.

[0095] Next, 10 mg of negative electrode compound was added to the solid electrolyte layer (lower punch side), the lower punch was inserted on top of it, and this third unit was placed in a press machine and molded at a pressure of 373 MPa.

[0096] Next, the upper punch was removed, and the positive electrode current collector (aluminum foil, 10 mm in diameter, 20 μm thick) and the upper punch were inserted on top of the positive electrode active material layer in that order. The lower punch was also removed, and the negative electrode current collector (copper foil, 10 mm in diameter, 10 μm thick) and the lower punch were inserted on top of the negative electrode active material layer in that order to obtain the fourth unit. In this way, an energy storage element consisting of a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector was fabricated.

[0097] Next, a stainless steel disc and a bakelite disc, both 50 mm in diameter and 5 mm thick, each with four screw holes, were prepared, and the battery elements were assembled as follows: The stainless steel disc / bakelite disc / fourth unit / bakelite disc / stainless steel disc were stacked in that order, and the four screws were tightened to create the fifth unit. Screws for connecting external terminals were inserted into the screw holes on the sides of the upper and lower punches.

[0098] -Storage Process- Next, the obtained energy storage elements were housed in an outer casing. The housing of the energy storage elements was carried out in a dry room with a dew point of -50°C.

[0099] A4-sized aluminum laminate bag was prepared as the outer casing for enclosing the fifth unit. On one side of the opening of the aluminum laminate bag, an aluminum foil (4mm wide, 40mm long, 100μm thick) wrapped with maleic anhydride-grafted polypropylene (PP) and a nickel foil (4mm wide, 40mm long, 100μm thick) were heat-bonded together with a gap to prevent short circuits, serving as external terminals. The fifth unit was inserted into the aluminum laminate bag with the external terminals attached, and the screws on the side of the upper punch and the aluminum terminals extending into the outer casing, as well as the screws on the side of the lower punch and the nickel terminals extending into the outer casing, were connected with lead wires.

[0100] Finally, the inside of the outer casing was evacuated to a vacuum of -50kPa (calculated with atmospheric pressure as 0kPa), and the opening was heat-sealed to create an all-solid-state battery. The internal pressure inside the outer casing was 51.3kPa. The difference between the external and internal pressures was 50kPa.

[0101] After performing the following charge-discharge tests, the positive and negative electrode current collectors were removed, and the surfaces of the contact points with the positive or negative electrode active material layer were observed using an optical microscope (50x objective lens). The area of ​​the region with a different contrast from the unused positive or negative electrode current collector was determined. This contrast change is presumed to be due to cracks.

[0102] Next, charge and discharge tests were performed on the fabricated all-solid-state battery. The charge and discharge tests were conducted in a constant temperature chamber at 25°C. Charging was performed at 0.05C to 2.8V using constant current and constant voltage (CCCV). Charging was completed when the current was reduced to 1 / 40C. Discharging was performed at 0.05C to 1.3V using constant current discharge. 50 cycles of charging and discharging were performed under the above conditions, and the maintenance rate after 50 cycles was calculated using the following formula (2).

[0103] Maintenance rate [%] = (Discharge capacity at 50th cycle [Ah] / Charge capacity at 1st cycle [Ah]) × 100 ... (2)

[0104] The results of Example 1 are summarized in Tables 1-5 below.

[0105] (Examples 2-10) Examples 2-10 differ from Example 1 in that the vacuum level inside the outer casing was changed. Other conditions were the same as in Example 1, and the discoloration of the positive electrode current collector and negative electrode current collector was observed, and the maintenance rate of the all-solid-state battery was measured. The results of Examples 2-10 are summarized in Table 1 below.

[0106] (Comparative Example 1) Comparative Example 1 differs from Example 1 in that the inside of the outer casing was not vacuumed when the opening of the outer casing was heat-sealed. The internal pressure was 101.3 kPa. The difference between the external and internal pressures was 0 kPa. Other conditions were the same as in Example 1, and the discoloration of the positive electrode current collector and the negative electrode current collector were observed, and the maintenance rate of the all-solid-state battery was measured. The results for Comparative Example 1 are summarized in Table 1 below.

[0107] (Example 11) Example 11 differed from Example 1 in that it used Li2ZrCl6, a solid electrolyte synthesized by weighing LiCl and ZrCl4 as raw material powders in a molar ratio of 2:1 and performing mechanochemical milling. Other conditions were the same as in Example 1, and the discoloration of the positive electrode current collector and the negative electrode current collector, as well as the maintenance rate of the all-solid-state battery, were measured. The results for Example 11 are summarized in Table 1 below.

[0108] (Examples 12-20) Examples 12-20 differ from Example 11 in that the vacuum level inside the outer casing was changed. Other conditions were the same as in Example 11, and the discoloration of the positive electrode current collector and the negative electrode current collector were observed, and the maintenance rate of the all-solid-state battery was measured. The results of Examples 12-20 are summarized in Table 1 below.

[0109] (Comparative Example 2) Comparative Example 2 differs from Example 11 in that the inside of the outer casing was not vacuumed when heat-sealing the opening of the outer casing. The internal pressure was 101.3 kPa. The difference between the external and internal pressures was 0 kPa. Other conditions, such as the observation of discoloration of the positive electrode current collector and the negative electrode current collector, were the same as in Example 11, and the maintenance rate of the all-solid-state battery was measured. The results for Comparative Example 2 are summarized in Table 1 below.

[0110] (Example 21) Example 21 differed from Example 1 in that it used Li2ZrOCl4, a solid electrolyte synthesized by weighing Li2O and ZrCl4 as raw material powders in a molar ratio of 1:1 and performing mechanochemical milling. Other conditions were the same as in Example 1, and the discoloration of the positive electrode current collector and the negative electrode current collector, as well as the maintenance rate of the all-solid-state battery, were measured. The results for Example 21 are summarized in Table 2 below.

[0111] (Examples 22-30) Examples 22-30 differ from Example 21 in that the vacuum level inside the outer casing was changed. Other conditions were the same as in Example 21, and the discoloration of the positive electrode current collector and the negative electrode current collector were observed, and the maintenance rate of the all-solid-state battery was measured. The results of Examples 22-30 are summarized in Table 2 below.

[0112] (Comparative Example 3) Comparative Example 3 differs from Example 21 in that the inside of the outer casing was not vacuumed when the opening of the outer casing was heat-sealed. The internal pressure was 101.3 kPa. The difference between the external and internal pressures was 0 kPa. Other conditions, such as the observation of discoloration of the positive electrode current collector and the negative electrode current collector, were the same as in Example 21, and the maintenance rate of the all-solid-state battery was measured. The results for Comparative Example 3 are summarized in Table 2 below.

[0113] (Example 31) Example 31 involved changing the composition of the solid electrolyte. In Example 31, Li3PO4 and ZrCl4 were weighed as raw material powders in a molar ratio of 1:3 and the solid electrolyte LiZr(PO4) was synthesized by mechanochemical milling. 0.33The difference from Example 1 is that Cl4 was used. Other conditions were the same as in Example 1, and the discoloration of the positive electrode current collector and the negative electrode current collector, and the maintenance rate of the all-solid-state battery were measured. The results of Example 31 are summarized in Table 2 below.

[0114] (Examples 32-40) Examples 32-40 differ from Example 31 in that the vacuum level inside the outer casing was changed. Other conditions were the same as in Example 31, and the discoloration of the positive electrode current collector and the negative electrode current collector were observed, and the maintenance rate of the all-solid-state battery was measured. The results of Examples 32-40 are summarized in Table 2 below.

[0115] (Comparative Example 4) Comparative Example 4 differs from Example 31 in that the inside of the casing was not vacuumed when the opening of the casing was heat-sealed. The internal pressure was 101.3 kPa. The difference between the external and internal pressures was 0 kPa. Other conditions, such as the observation of discoloration of the positive electrode current collector and the negative electrode current collector, were the same as in Example 31, and the maintenance rate of the all-solid-state battery was measured. The results for Comparative Example 4 are summarized in Table 2 below.

[0116] (Example 41) Example 41 involved changing the composition of the solid electrolyte. In Example 41, Li3PO4 and YCl3 were weighed as raw material powders in a molar ratio of 1:3 and the solid electrolyte LiY(PO4) was synthesized by mechanochemical milling. 0.33 The difference from Example 1 is that Cl3 was used. Other conditions were the same as in Example 1, and the discoloration of the positive electrode current collector and the negative electrode current collector, and the maintenance rate of the all-solid-state battery were measured. The results of Example 41 are summarized in Table 3 below.

[0117] (Examples 42-50) Examples 42-50 differ from Example 41 in that the vacuum level inside the outer casing was changed. Other conditions were the same as in Example 41, and the discoloration of the positive electrode current collector and the negative electrode current collector were observed, and the maintenance rate of the all-solid-state battery was measured. The results of Examples 42-50 are summarized in Table 3 below.

[0118] (Comparative Example 5) Comparative Example 5 differs from Example 41 in that the inside of the outer casing was not vacuumed when the opening of the outer casing was heat-sealed. The internal pressure was 101.3 kPa. The difference between the external and internal pressures was 0 kPa. Other conditions, such as the observation of discoloration of the positive electrode current collector and the negative electrode current collector, were the same as in Example 41, and the maintenance rate of the all-solid-state battery was measured. The results of Comparative Example 5 are summarized in Table 3 below.

[0119] (Example 51) Example 51 involved changing the composition of the solid electrolyte. In Example 51, Li3PO4, ZrCl4, and AlCl3 were weighed as raw material powders in a molar ratio of 4.3:7:3, and the solid electrolyte Li was synthesized by mechanochemical milling. 1.3 Al 0.3 Zr 0.7 (PO4) 0.43 Cl 3.7 The difference from Example 1 is the use of [specific component / method]. Other conditions were the same as in Example 1, and the discoloration of the positive electrode current collector and the negative electrode current collector, as well as the maintenance rate of the all-solid-state battery, were measured. The results of Example 51 are summarized in Table 3 below.

[0120] (Examples 52-60) Examples 52-60 differ from Example 51 in that the vacuum level inside the outer casing was changed. Other conditions were the same as in Example 51, and the discoloration of the positive electrode current collector and the negative electrode current collector were observed, and the maintenance rate of the all-solid-state battery was measured. The results of Examples 52-60 are summarized in Table 3 below.

[0121] (Comparative Example 6) Comparative Example 6 differs from Example 51 in that the inside of the casing was not vacuumed when the opening of the casing was heat-sealed. The internal pressure was 101.3 kPa. The difference between the external and internal pressures was 0 kPa. Other conditions, such as the observation of discoloration of the positive electrode current collector and the negative electrode current collector, were the same as in Example 51, and the maintenance rate of the all-solid-state battery was measured. The results for Comparative Example 6 are summarized in Table 3 below.

[0122] (Example 61) Example 61 involved changing the composition of the solid electrolyte. In Example 61, Li2SO4 and ZrCl4 were weighed as raw material powders in a molar ratio of 0.9:1 and the solid electrolyte Li was synthesized by mechanochemical milling. 1.8 Zr(SO4) 0.9 The difference from Example 1 is that Cl4 was used. Other conditions were the same as in Example 1, and the discoloration of the positive electrode current collector and the negative electrode current collector, and the maintenance rate of the all-solid-state battery were measured. The results of Example 61 are summarized in Table 4 below.

[0123] (Examples 62-70) Examples 62-70 differ from Example 61 in that the vacuum level inside the outer casing was changed. Other conditions were the same as in Example 61, and the discoloration of the positive electrode current collector and the negative electrode current collector were observed, and the maintenance rate of the all-solid-state battery was measured. The results of Examples 62-70 are summarized in Table 4 below.

[0124] (Comparative Example 7) Comparative Example 7 differs from Example 61 in that the inside of the casing was not vacuumed when the opening of the casing was heat-sealed. The internal pressure was 101.3 kPa. The difference between the external and internal pressures was 0 kPa. Other conditions, such as the observation of discoloration of the positive electrode current collector and the negative electrode current collector, were the same as in Example 61, and the maintenance rate of the all-solid-state battery was measured. The results for Comparative Example 7 are summarized in Table 4 below.

[0125] (Example 71) Example 71 involved changing the composition of the solid electrolyte. In Example 71, Li2SO4 and ZrCl4 were weighed as raw material powders in a molar ratio of 1.1:1 and the solid electrolyte Li was synthesized by mechanochemical milling. 2.2 Zr(SO4) 1.1 The difference from Example 1 is that Cl4 was used. Other conditions were the same as in Example 1, and the discoloration of the positive electrode current collector and the negative electrode current collector, and the maintenance rate of the all-solid-state battery were measured. The results of Example 71 are summarized in Table 4 below.

[0126] (Examples 72-80) Examples 72-80 differ from Example 71 in that the vacuum level inside the outer casing was changed. Other conditions were the same as in Example 71, and the discoloration of the positive electrode current collector and the negative electrode current collector were observed, and the maintenance rate of the all-solid-state battery was measured. The results of Examples 72-80 are summarized in Table 4 below.

[0127] (Comparative Example 8) Comparative Example 8 differs from Example 71 in that the inside of the casing was not vacuumed when the opening of the casing was heat-sealed. The internal pressure was 101.3 kPa. The difference between the external and internal pressures was 0 kPa. Other conditions, such as the observation of discoloration of the positive electrode current collector and the negative electrode current collector, were the same as in Example 71, and the maintenance rate of the all-solid-state battery was measured. The results of Comparative Example 8 are summarized in Table 4 below.

[0128] (Example 81) Example 81 involved a change in the composition of the solid electrolyte. In Example 81, Li2SO4 and ZrCl4 were weighed as raw material powders in a molar ratio of 1.5:1 and the solid electrolyte Li3Zr(SO4) was synthesized by mechanochemical milling. 1.5 The difference from Example 1 is that Cl4 was used. Other conditions were the same as in Example 1, and the discoloration of the positive electrode current collector and the negative electrode current collector, and the maintenance rate of the all-solid-state battery were measured. The results of Example 81 are summarized in Table 5 below.

[0129] (Examples 82-90) Examples 82-90 differ from Example 81 in that the vacuum level inside the outer casing was changed. Other conditions were the same as in Example 81, and the discoloration of the positive electrode current collector and the negative electrode current collector were observed, and the maintenance rate of the all-solid-state battery was measured. The results of Examples 82-90 are summarized in Table 5 below.

[0130] (Comparative Example 9) Comparative Example 9 differs from Example 81 in that the inside of the outer casing was not vacuumed when the opening of the outer casing was heat-sealed. The internal pressure was 101.3 kPa. The difference between the external and internal pressures was 0 kPa. Other conditions, such as the observation of discoloration of the positive electrode current collector and the negative electrode current collector, were the same as in Example 81, and the maintenance rate of the all-solid-state battery was measured. The results for Comparative Example 9 are summarized in Table 5 below.

[0131] [Table 1]

[0132] [Table 2]

[0133] [Table 3]

[0134] [Table 4]

[0135] [Table 5]

[0136] In Tables 1-5, the vacuum level inside the outer casing is calculated using atmospheric pressure as 0 kPa. In Examples 1-90, the internal pressure in the containment space K was less than 101.3 kPa, discoloration of the positive and negative electrode current collectors was suppressed, and the maintenance rate after 50 cycles was better than that of the all-solid-state batteries in Comparative Examples 1-9. The solid electrolytes used were Li2ZrSO4Cl4, Li2ZrOCl4, and Li 1.8 Zr(SO4) 0.9 Cl4, Li 2.2 Zr(SO4) 1.1 Cl4, Li3Zr(SO4) 1.5 When Cl4 was used, the retention rate was good at over 80% at 30 kPa or higher. Solid electrolytes included Li2ZrCl6 and LiZr(PO4). 0.33 Cl4, LiY(PO4) 0.33 Cl3, Li 1.3 Al 0.3 Zr 0.7 (PO4) 0.43 Cl 3.7When using this method, the maintenance rate was good, exceeding 80% at 40kPa or higher. [Industrial applicability]

[0137] The battery of this embodiment has excellent cycle characteristics and is suitably applied as a power source for portable electronic devices where miniaturization, weight reduction, thinning, and improved reliability are strongly desired. [Explanation of Symbols]

[0138] 11...Positive electrode, 11A...Positive electrode current collector, 11B...Positive electrode active material layer, 12...External terminal, 13...Negative electrode, 13A...Negative electrode current collector, 13B...Negative electrode active material layer, 14...External terminal, 15...Solid electrolyte layer, 10...Energy storage element, 20...Outer casing, 22...Metal foil, 24...Resin layer 24, K...Housing space, 100...All-solid-state battery

Claims

1. The energy storage element comprises a positive electrode, a negative electrode, and a solid electrolyte layer between the positive electrode and the negative electrode, and an outer casing covering the energy storage element, wherein at least one of the positive electrode, the negative electrode, and the solid electrolyte layer contains a solid electrolyte represented by the following formula (1), Li ３＋ａ－ｅ E １－ｂ G ｂ D ｃ X ｄ－ｅ ・・・(1) In equation (1), E is at least one element selected from the group consisting of Al, Sc, Y, Zr, Hf, and lanthanides. G is at least one element selected from the group consisting of Na, K, Rb, Cs, Mg, Ca, Sr, Ba, B, Si, Al, Ti, Cu, Sc, Y, Zr, Nb, Ag, In, Sn, Sb, Hf, Ta, W, Au, and Bi. D is CO ３ , SO ４ , BO ３ , PO ４ , NO ３ , SiO ３ , OH, O ２ is at least one selected from the group consisting of, X is at least one element selected from the group consisting of F, Cl, Br, and I, and when n = (valence of E) - (valence of G), then a = nb, 0 ≤ b < 0.5, 0 ≤ c ≤ 5, 0 < d ≤ 7.1, 0 ≤ e ≤ 2, 0 < d - e, In equation (1), when b = 0 (i.e., G is not included), a = 0, The internal pressure within the containment space surrounded by the aforementioned outer casing is less than 101.3 kPa. The internal pressure is less than the external pressure acting on the outer casing, and the pressure difference between the external pressure and the internal pressure is 30 kPa or more and 100 kPa or less. The gas contained within the outer casing is one selected from argon, nitrogen, oxygen, carbonic acid, neon, helium, and hydrogen. A battery in which the amount of moisture in the containment space surrounded by the outer casing is 1100 ppmv or less.

2. A device manufacturing process involves sandwiching a solid electrolyte layer between a positive electrode and a negative electrode, and then press-molding these together to produce an energy storage element. A step of preparing an exterior body having an opening, The process of housing the energy storage element inside the outer casing, The process includes the steps of vacuuming the inside of the outer casing to reduce the internal pressure in the containment space to less than 101.3 kPa, and sealing the opening of the outer casing. At least one of the positive electrode, the negative electrode, and the solid electrolyte layer includes a solid electrolyte represented by the following formula (1): Li ３＋ａ－ｅ E １－ｂ G ｂ D ｃ X ｄ－ｅ ・・・(1) In equation (1), E is at least one element selected from the group consisting of Al, Sc, Y, Zr, Hf, and lanthanides. G is at least one element selected from the group consisting of Na, K, Rb, Cs, Mg, Ca, Sr, Ba, B, Si, Al, Ti, Cu, Sc, Y, Zr, Nb, Ag, In, Sn, Sb, Hf, Ta, W, Au, and Bi. D is CO ３ SO ４ , BO ３ , PO ４ NO ３ SiO ３ , OH, O ２ It is at least one selected from the group consisting of, X is at least one element selected from the group consisting of F, Cl, Br, and I, and when n = (valence of E) - (valence of G), then a = nb, 0 ≤ b < 0.5, 0 ≤ c ≤ 5, 0 < d ≤ 7.1, 0 ≤ e ≤ 2, 0 < d - e, In equation (1), when b = 0 (i.e., G is not included), a = 0, In the sealing process described above, the internal pressure acting on the outer casing is less than the external pressure, and the pressure difference between the external pressure and the internal pressure is 30 kPa or more and 100 kPa or less. A method for manufacturing a battery, wherein the gas contained within the outer casing is selected from argon, nitrogen, oxygen, carbon dioxide, neon, helium, and hydrogen.

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