Battery and laminate

Abstract

A battery comprising a positive electrode, a negative electrode, and electrolyte layers disposed between the positive electrode and the negative electrode, wherein: the electrolyte layers include a first electrolyte layer and a second electrolyte layer; the first electrolyte layer is disposed between the positive electrode and the second electrolyte layer; the first electrolyte layer contains a material different from that for the second electrolyte layer; the first electrolyte layer contains a solid electrolyte material containing an alkali metal element, a metalloid element or a metal element excluding alkali metal elements, and a halogen element; and the metalloid element or the metal element excluding alkali metal elements includes Zr and / or In.

Description

Battery and laminate

[0001] The present disclosure relates to batteries and laminates.

[0002] Batteries such as lithium-ion batteries, which charge and discharge through the movement of metal ions between the positive and negative electrodes, have been the subject of active research due to their high capacity. While solutions of lithium salts containing organic solvents or ionic liquids are known as electrolytes for lithium-ion batteries, research into solid electrolytes is also underway from the perspectives of safety and processability. Various types of compounds are known as solid electrolytes, including oxide-based solid electrolytes and sulfide-based solid electrolytes.

[0003] International Publication No. 2019 / 135323 International Publication No. 2021 / 002064

[0004] However, batteries equipped with conventional solid electrolytes have not been able to sufficiently reduce resistance, and are prone to microcracks and the like in the electrolyte layer.

[0005] The present disclosure has been made in view of the above circumstances, and has an object to provide a battery and a laminate in which microcracks are less likely to occur in layers including an electrolyte layer.

[0006] The present disclosure includes the following embodiments [1] to [8]. [1] A battery comprising: a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode, wherein the electrolyte layer includes a first electrolyte layer and a second electrolyte layer, wherein the first electrolyte layer is disposed between the positive electrode and the second electrolyte layer, and wherein the first electrolyte layer includes a material different from that of the second electrolyte layer, and wherein the first electrolyte layer includes a solid electrolyte material containing an alkali metal element, a metal element or a metalloid element other than the alkali metal element, and a halogen element, and wherein the metal element or the metalloid element other than the alkali metal element includes at least one of Zr and In. [2] The solid electrolyte material is A α M β Z γ D ζ O η

[0023] The battery according to [1], wherein A is an alkali metal element, M is a metal element or a metalloid element other than an alkali metal element, Z is a halogen element, D is at least one of P and S, and 1.6≦α≦3.5, 0<β≦1.2, 3≦γ≦6.5, 0≦ζ≦0.5, and 0≦η≦2. [3] The battery according to [1] or [2], wherein the second electrolyte layer contains an oxide solid electrolyte. [4] The battery according to any one of [1] to [3], wherein the thickness ratio of the first electrolyte layer to the second electrolyte layer is 1:0.2 to 1:1. [5] The battery according to any one of [1] to [4], wherein the first electrolyte layer further contains an ionic liquid. [6] The battery according to any one of [1] to [5], wherein a laminate including the positive electrode and the first electrolyte layer is sandwiched between two SUS plates, and impedance measurements are performed in the range of 0.1 Hz to 891 kHz. In the Nyquist plot obtained, the frequency at which the phase angle is smallest is 100 kHz to 891 kHz, and the ratio A / B of the resistance value (A) of the real part of the impedance measurement at the frequency at which the phase angle is smallest to the resistance value (B) of the real part of the impedance at 891 kHz is 1.0 to 3.5. [7] A laminate comprising: a positive electrode; and an electrolyte layer disposed on the positive electrode; wherein the electrolyte layer includes a first electrolyte layer and a second electrolyte layer; the first electrolyte layer is disposed between the positive electrode and the second electrolyte layer; the first electrolyte layer includes a material different from that of the second electrolyte layer; the first electrolyte layer includes a solid electrolyte material containing an alkali metal element, a metal element or a metalloid element other than the alkali metal element, and a halogen element; and the metal element or the metalloid element other than the alkali metal element includes at least one of Zr and In. [8] The laminate according to [7], wherein a Nyquist plot obtained by sandwiching a laminate made of the positive electrode and the first electrolyte layer between two SUS plates and measuring impedance in the range of 0.1 Hz to 891 kHz shows that the frequency at which the phase angle is smallest is 100 kHz to 891 kHz, and the ratio A / B of the resistance value (A) of the real part of the impedance measurement at the frequency at which the phase angle is smallest to the resistance value (B) of the real part of the impedance at 891 kHz is 1.0 to 3.5.

[0007] According to the present disclosure, it is possible to provide a battery and a laminate in which microcracks are unlikely to occur in layers including an electrolyte layer.

[0008] FIG. 1 is a diagram showing the results of a charge / discharge test of the secondary battery of Example 1. FIG. 2 is a diagram showing the results of a charge / discharge test of the secondary battery of Example 2. FIG. 3 is a scanning electron microscope image of the solid electrolyte material of Example 3. FIG. 4 is an enlarged view of a portion of FIG. 3. FIG. 5 is a scanning electron microscope image of a cross section of the laminate of Example 3. FIG. 6 is a scanning electron microscope image of the solid electrolyte material of Comparative Example 1. FIG. 7 is an enlarged view of a portion of FIG. 6. FIG. 8 is a scanning electron microscope image of a cross section of the laminate of Comparative Example 1. FIG. 9 is a Nyquist plot of the laminates of Example 3 and Comparative Example 1.

[0009] The battery of this embodiment includes a positive electrode (which may be a positive electrode layer), a negative electrode (which may be a negative electrode layer), and an electrolyte layer disposed between the positive electrode and the negative electrode. The electrolyte layer includes a first electrolyte layer and a second electrolyte layer. The first electrolyte layer is disposed between the positive electrode and the second electrolyte layer. The first electrolyte layer includes a material different from that of the second electrolyte layer. The first electrolyte layer includes a solid electrolyte material containing an alkali metal element, a metal element or a metalloid element other than the alkali metal element, and a halogen element. The metal element or metalloid element other than the alkali metal element may include at least one of Zr and In.

[0010] A laminate including a positive electrode and a first electrolyte layer may be sandwiched between two SUS plates, and the Nyquist plot obtained by measuring impedance in the range of 0.1 Hz to 891 kHz may have a frequency of 100 kHz to 891 kHz at which the phase angle is smallest, and a ratio A / B of the resistance value (A) of the impedance measurement to the resistance value (B) of the real part of the impedance at 891 kHz may be 1.0 to 3.5.

[0011] The ratio A / B may be 1.0 to 3.0, or may be 1.0 to 2.8. The frequency at which the phase angle is smallest may be 200 kHz or higher, or may be 220 kHz or higher.

[0012] The electrolyte layer includes a solid electrolyte material (halide-based solid electrolyte) containing an alkali metal element, a metal element or metalloid element other than the alkali metal element, and a halogen element. Hereinafter, a solid electrolyte material containing an alkali metal element, a metal element or metalloid element other than the alkali metal element, and a halogen element will also be referred to as a first solid electrolyte material. The first solid electrolyte material may satisfy at least one of the following (A) to (C): (A) The first solid electrolyte material contains In as the metal element other than the alkali metal element. (B) The first solid electrolyte material contains Zr as the metal element other than the alkali metal element, and contains two or more halogen elements. (C) The first solid electrolyte material further contains oxygen.

[0013] The alkali metal element contained in the first solid electrolyte material may be any of Li, Na, K, Rb, and Cs, but may include at least one of Li, Na, and K, may include at least one of Li and Na, or may include Li.

[0014] The proportion of one alkali metal element among the alkali metal elements contained in the first solid electrolyte material may be 80 mol % or more, 90 mol % or more, or 95 mol % or more. The one alkali metal element may be at least one of Li, Na, and K, at least one of Li and Na, or Li.

[0015] The content of the alkali metal element in the first solid electrolyte material may be 15 to 30 mol %, 18 to 28 mol %, or 20 to 27 mol % relative to the total amount of atoms contained in the first solid electrolyte material.

[0016] The metal element or metalloid element other than the alkali metal element is not particularly limited, but examples thereof include divalent to pentavalent elements, and may include one or more elements selected from the group consisting of trivalent elements and tetravalent elements. The first solid electrolyte material may include one or more metal elements or metalloid elements other than the alkali metal element.

[0017] Examples of divalent elements include alkaline earth metals and Zn. The alkaline earth metal may be at least one of Mg, Ca, Sr, and Ba, or may be at least one of Mg and Ca, or may be Mg. Examples of trivalent metal elements include Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Y, Al, Ga, In, Bi, and Sb. Examples of tetravalent elements include Zr, Ti, Hf, and Sn, and may be Zr. Examples of pentavalent metal elements include Nb and Ta. Examples of hexavalent or higher elements include W.

[0018] The metal element or metalloid element other than alkali metal elements may include at least one of In and Zr. The content of the metal element or metalloid element other than alkali metal elements in the first solid electrolyte material is preferably 8 to 15 mol %, more preferably 8 to 13 mol %, and even more preferably 9 to 12 mol %, based on all elements contained in the first solid electrolyte material.

[0019] In the first solid electrolyte material, the total amount of Zr and In may be greater than the total amount of alkali metal elements and metal or semi-metal elements other than Zr and In. Note that, when the first solid electrolyte material contains only one of Zr and In, this total amount of Zr and In refers to the content of the contained element. The total amount of Zr and In in the first solid electrolyte material may be 60 mol % or more, 70 mol % or more, 80 mol % or more, or 90 mol % or more of the total amount of metal or semi-metal elements other than alkali metal elements.

[0020] In the first solid electrolyte material, the content of Y in terms of substance amount may be less than the total substance amount of Zr and In. Note that, when the first solid electrolyte material contains only one of Zr and In, this total substance amount is the content of the contained element. The content of Y in the first solid electrolyte may be 40 mol% or less, 30 mol% or less, 20 mol% or less, or 10 mol% or less, relative to the total substance amount of metal elements or metalloid elements other than alkali metal elements. The first solid electrolyte material may be substantially free of Y.

[0021] The first solid electrolyte material may contain one element selected from metal elements or metalloid elements other than alkali metal elements in an amount of 70 mol% or more, 75 mol% or more, or 80 mol% or more relative to the total amount of metal elements or metalloid elements other than alkali metal elements. In this case, the one element may be a trivalent or tetravalent element, such as In or Zr. In this case, the first solid electrolyte material contains a metal element or metalloid element other than alkali metal elements (also referred to as a dopant element X1) other than the one element. The dopant element X1 is an element different from the one element. When the one element is a trivalent element, the dopant element X1 may be at least one element selected from the group consisting of Zr, Sn, Ti, Nb, Ta, Bi, and Y, or may be at least one element selected from the group consisting of Zr, Sn, Nb, and Ta. When the one element is a tetravalent element, the dopant element X1 may be at least one element selected from the group consisting of Bi, Al, Ga, In, Sc, Sm, Sb, La, Zn, Sn, and alkaline earth metals, or at least one element selected from the group consisting of Bi, La, Zn, and Sn. An example of a hexavalent or higher element is W.

[0022] The halogen element contained in the first solid electrolyte material of this embodiment may be any of F, Cl, Br, and I, but may include at least one of Cl, Br, and I, may include at least one of Cl and Br, or may include Cl. The ion-conductive substance may include only one halogen element, or may include two or more halogen elements. When the first solid electrolyte material includes Zr as a metal element other than an alkali metal element, the first solid electrolyte material may include two or more halogen elements, may include Cl and a halogen element other than Cl, or may include Cl and Br. The content of the halogen element other than Cl or Br may be 10% by mole or less, may be 0.1 to 10 mol%, or may be 1 to 8 mol% relative to the total amount of halogen elements contained in the first solid electrolyte material.

[0023] The content of the halogen element in the first solid electrolyte material is preferably 40 to 70 mol %, more preferably 45 to 68 mol %, based on the total amount of elements contained in the halogen element.

[0024] The first solid electrolyte material may contain one of the halogen elements in an amount of 80 mol% or more, 85 mol% or more, or 90 mol% or more relative to the total amount of the halogen elements. The one halogen element may be Cl or Br, and may be Cl. In this case, the first solid electrolyte material contains a halogen element (also referred to as a dopant element X2) other than the one halogen element. When the one halogen element is Cl, the dopant element X2 may be at least one of Br and I, and may be Br.

[0025] The first solid electrolyte material may contain at least one of P and S (also referred to as dopant element X3). The content of the dopant element X3 in the first solid electrolyte material may be 0.05 to 5 mol %, 0.1 to 3 mol %, 0.2 to 2 mol %, or 0.3 to 1 mol % relative to the total amount of atoms contained in the first solid electrolyte material.

[0026] When the first solid electrolyte material contains at least one of P and S, the first solid electrolyte material may contain a tetravalent metal element or metalloid element. Examples of the tetravalent metal element or metalloid element include Zr, Ti, Hf, etc., and Zr may be used. The dopant element X2 may also contain at least one of Hf and Mg. The content of the dopant element X3 in the first solid electrolyte material may be 50 mol% or less, 1 to 30 mol%, 1 to 20 mol%, or 2 to 10 mol% of the content of the tetravalent metal element or metalloid element. The content of the dopant element X in the first solid electrolyte material may be 20 mol% or less, 15 mol% or less, 10 mol% or less, or 8 mol% or less of the content of the tetravalent metal element or metalloid element.

[0027] The first solid electrolyte material may have a hexagonal crystal structure and a space group P6 ３The solid electrolyte material having a hexagonal crystal structure may contain at least one element selected from the group consisting of Sc, La, Y, Ga, In, Bi, Sb, Ge, Zr, Sn, Nb, and Ta, and may contain Sc.

[0028] The first solid electrolyte material may contain a compound represented by the following formula (A): α M β Z γ D ζ O η ...(A) Here, A is an alkali metal, M is a metal element or a metalloid element other than an alkali metal element, Z is a halogen element, D is at least one of P and S, and 1.6≦α≦3.5, 0<β≦1.2, 3≦γ<6.5, 0≦ζ≦0.5, 0≦η≦2.

[0029] Examples of the compound represented by formula (A) include compounds represented by the following formulas (1) to (3): α１ M β１ Z ６－δ１ X1 ε１１ X2 ε１２ ... (1) A α２ M β２ X2 ε２１ Z ６－γ２ X1 ε２２ ... (2) A α３ M β３ X1 ε３１ Z δ3 D ζ O η ...(3)

[0030] In formula (1), A, M, and Z are each an alkali metal element, a trivalent metal element or metalloid element, or a halogen element, specific examples of which are listed above. M preferably contains In. X1 and X2 are dopant element X1 and dopant element X2, respectively, specific examples of which are listed above. 2≦α1≦3.5, or 2.5≦α1≦3, may be satisfied. 0.5≦β1≦1.1, or 0.5≦β1≦1, may be satisfied. 0≦δ1≦1, or 0≦δ1≦0.5, may be satisfied. 0≦ε11≦0.7, or 0<ε11≦0.5, or 0.01≦ε11≦0.3, may be satisfied. 0≦ε12≦0.7, or 0<ε11≦0.5, or 0.01≦ε11≦0.3, may be satisfied.

[0031] In formula (2), A, M, and Z are each an alkali metal element, a tetravalent metal element or metalloid element, or a halogen element, specific examples of which are listed above. M preferably includes Zr. X1 and X2 are dopant element X1 and dopant element X2, respectively, specific examples of which are listed above. α2 may be 1.6≦α2≦2.5, 1.8≦α2≦2.4, or 2≦α2≦2.3. β2 may be 0<β2≦1.1, 0.5≦β2≦1, or 0.8≦β2≦1. γ2 may be 0≦γ2<1, 0.01≦γ2≦0.8, 0.02≦γ2≦0.7, 0.1≦γ2≦0.6, or 0.2≦γ2≦0.6. ε21 may be 0≦ε21≦0.7, 0<ε21≦0.5, or 0.01≦ε21≦0.3. ε22 may be 0≦ε22≦0.8, or 0<ε21≦0.6. When X2 is iodine, ε21 may be 0.01≦ε21≦0.3, or 0.015≦ε21≦0.1.

[0032] In formula (3), A, M, and Z are each an alkali metal element, a tetravalent metal element or metalloid element, or a halogen element, specific examples of which are listed above. M preferably includes Zr. X1 and D are dopant element X1 and dopant element X3, respectively, specific examples of which are listed above. α may be 1.5≦α≦3, 1.8≦α≦2.5, 1.9≦α≦2.3, or 1.95≦α≦2.2. β may be 0.5≦β≦2, 0.7≦β≦1.4, 0.8≦β≦1.2, or 0.9≦β≦1.1. ζ may be 0.005≦ζ≦0.5, 0.01≦ζ≦0.2, 0.02≦ζ≦0.15, or 0.025≦ζ≦0.10. 3.5≦δ3≦5, 3.7≦δ3≦4.3, or 3.8≦δ3≦4.1. 0.1≦η≦1.5, 0.7≦η≦1.5, 0.8≦η≦1.3, or 0.9≦η≦1.1.

[0033] The first solid electrolyte material may be in a particulate form. In this case, the average particle size of the first solid electrolyte material may be 1 to 50 μm. The particles of the first solid electrolyte material may have an uneven structure with a size of 0.5 to 2 μm. The particles of the first solid electrolyte material may be free of microcracks with a size of 0.5 μm or more.

[0034] The method for producing the first solid electrolyte material is not particularly limited, but may include, for example, a method including a step of ball milling the raw material. The product after ball milling may be annealed. Furthermore, when a hexagonal solid electrolyte material is to be obtained, the method for producing the first solid electrolyte material may include a step of heating the raw material under a pressure of 1 GPa or more.

[0035] The raw materials are not particularly limited and may be, for example, alkali metal halides, chlorides of metal elements or semimetal elements other than alkali metals, and compounds containing dopant element X1 or X2. When the dopant element is X1, the compound containing the dopant element may be a halide of X1. When the dopant element is X2, the compound containing the dopant element may be an alkali metal bromide or alkali metal iodide. The raw materials are preferably mixed before ball milling, and more preferably mixed in an inert atmosphere (e.g., an Ar atmosphere).

[0036] The conditions for the ball mill are not particularly limited, but can be 10 to 100 hours at a rotation speed of 200 to 700 rpm. The milling time is preferably 24 to 72 hours, more preferably 36 to 60 hours. The balls used in the ball mill are not particularly limited, but zirconia balls can be used. The size of the balls used is not particularly limited, but balls of 2 mm to 10 mm can be used. By performing ball milling for the above-mentioned time, the raw materials are thoroughly mixed, and the mechanochemical reaction is promoted, making it possible to improve the ionic conductivity of the resulting compound.

[0037] The ball mill may have multiple steps with different rotation speeds. For example, the ball milling process may include a first step, a second step, and a third step in this order, and the second step may have a higher rotation speed than the first and third steps. In this case, the third step may have a higher rotation speed than the first step.

[0038] The annealing is preferably carried out in an inert atmosphere or in a vacuum. The annealing temperature is, for example, preferably 150 to 300° C., more preferably 200 to 250° C. The annealing time may be, for example, 1 to 10 hours, preferably 3 to 6 hours.

[0039] The positive electrode active material is not particularly limited, and examples thereof include alkali metal composite oxides containing an alkali metal element and at least one metal element selected from the group consisting of a transition metal element and Al. The transition metal element may be at least one element selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, and Cu, and may contain Ni. For example, when the alkali metal element is lithium (i.e., in the case of a lithium composite oxide), examples of the lithium composite oxide include LiCoO ２ , LiNiO ２ , LiMn ２ O ４ , LiNi ０．５ Mn １．５ O ４ , Li ２ MnO ３ , LiNi ｘ Mn ｙ Co １－ｘ－ｙ O ２ [0<x+y<1]), LiNi ｘ Co ｙ Al １－ｘ－ｙ O ２ [0<x+y<1]), LiCr ０．５ Mn ０．５ O ２ , LiFePO ４ , Li ２ FeP ２ O ７ , LiMnPO ４ , LiFeBO ３ , Li ３ V ２ (P.O. ４ ) ３ , Li ２ CuO ２ , Li ２ FeSiO ４ , Li ２ MnSiO ４ When the positive electrode active material contains an alkali metal element other than Li, specific examples thereof include those in which Li in the above specific examples is replaced with another alkali metal. Examples of alkali metals other than Li include Na and K.

[0040] The positive electrode (positive electrode material) of this embodiment may further contain a solid electrolyte material, a binder resin, a conductive additive, and the like. Examples of the binder resin include, but are not limited to, fluororesins. Resins having a carbon chain as the main chain are preferred as fluororesins. The carbon chain may be formed by radical polymerization of an ethylenically unsaturated group. Examples of fluororesins include poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and polyvinylidene fluoride (PVDF). The content of the binder resin in the positive electrode may be 0.5 to 10% by mass, or 1 to 7% by mass. Examples of the conductive additive include graphites such as natural graphite (e.g., flake graphite) and artificial graphite; carbon blacks such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; and carbon fibers. The content of the conductive additive in the positive electrode may be 0.5 to 10 mass %, or may be 1 to 7 mass %. The solid electrolyte material contained in the positive electrode may be one or both of the first solid electrolyte material and the second solid electrolyte material described above.

[0041] The content of the positive electrode active material in the positive electrode material (or positive electrode) may be 50% by mass or more, 60% by mass or more, or 70% by mass or more, and may be 95% by mass or less, or 90% by mass or less, relative to the total amount of the positive electrode material.

[0042] The negative electrode material may contain a negative electrode active material, and, if necessary, a polymer electrolyte, a binder resin, a conductive additive, an organic solvent, an ionic liquid, and the like.

[0043] Examples of the negative electrode active material include simple substances such as alkali metal elements, Si, P, Sn, Si—Mn, Si—Co, Si—Ni, In, and Au, as well as alloys or composites containing these elements, carbon materials such as graphite, substances in which alkali metal ions are inserted between layers of the carbon material, oxides containing titanium, etc. The alkali metal element may be Li, Na, or K, or may be Li, Na, or Li.

[0044] The oxide containing titanium has the composition formula: A ｓTiO ｔ (A is an alkali metal element, and s≧0). Here, the alkali metal element A may be Li, Na, or K, or may be Li, Na, or Li.

[0045] The first electrolyte layer may be formed from a first electrolyte composition. The first electrolyte composition may contain a solid electrolyte material and, as necessary, a polymer electrolyte, a binder resin, an organic solvent, an ionic liquid, etc. The solid electrolyte material may contain at least one of the above-mentioned first solid electrolyte material and, optionally, a solid electrolyte material (second solid electrolyte material) other than the first solid electrolyte material.

[0046] The second solid electrolyte material is not particularly limited and may be an oxide (oxide-based solid electrolyte), a sulfide (sulfide-based solid electrolyte), a hydride (hydride-based solid electrolyte), or the like. The second solid electrolyte material may contain an alkali metal element.

[0047] (Oxide-Based Solid Electrolyte) Examples of oxide-based solid electrolytes include oxides such as perovskite-type oxides, NASICON-type oxides, LISICON-type oxides, and garnet-type oxides, as well as oxides doped with other cations or anions.

[0048] As the perovskite oxide, Li ａ La １－ａ TiO ３ (0<a<1) and other Li-La-Ti oxides, Li ｂ La １－ｂ TaO ３ Li-La-Ta oxides such as (0<b<1), Li ｃ La １－ｃ NbO ３ Examples include Li-La-Nb oxides such as (0<c<1).

[0049] As the NASICON type oxide, Li １＋ｄ Al ｄ Ti ２－ｄ (P.O. ４ ) ３ (0≦d≦1) and the like. NASICON-type oxides include Li ｍ M１ ｎ M ２ ｏ P ｐ O ｑ (In the formula, M １ is one or more elements selected from the group consisting of B, Al, Ga, In, C, Si, Ge, Sn, Sb and Se. ２ is one or more elements selected from the group consisting of Ti, Zr, Ge, In, Ga, Sn and Al; m, n, o, p and q are any positive numbers. １＋ｘ＋ｙ Al ｘ (Ti, Ge) ２－ｘ Si ｙ P ３－ｙ O １２ (0<x<2, 0<y<3) (LATP) and the like.

[0050] As the LISICON type oxide, Li ４ M ３ O ４ -Li ３ M ４ O ４ (M ３ is one or more elements selected from the group consisting of Si, Ge, and Ti. ４ is one or more elements selected from the group consisting of P, As and V.

[0051] Garnet-type oxides include Li ７ La ３ Zr ２ O １２ (LLZ), Li ７－ａ２ La ３ Zr ２－ａ２ Ta ａ２ O １２ Examples include Li-La-Zr oxides such as LLZT (where 0<a2<1, 0.1<a2<0.8, and 0.2<a2<0.6).

[0052] The oxide-based solid electrolyte may be a crystalline material or an amorphous material.

[0053] The oxide-based solid electrolyte is Li ６．６ La ３ Zr １．６Ta ０．４ O １２ , Li ０．３３ La ０．５５ TiO ３ etc.

[0054] (Sulfide-based solid electrolyte) As the sulfide-based solid electrolyte, Li ２ S-P ２ S ５ based compound, Li ２ S-SiS ２ based compound, Li ２ S-GeS ２ based compound, Li ２ S-B ２ S ３ based compound, Li ２ S-P ２ S ３ system compound, LiI-Si ２ S-P ２ S ５ , LiI-Li ２ S-P ２ O ５ , LiI-Li ３ P.O. ４ -P ２ S ５ , Li １０ GeP ２ S １２ Examples include:

[0055] In this specification, the expression "sulfide-based compound" referring to a sulfide-based solid electrolyte is the same as the expression "Li ２ S" "P" ２ S ５ " is used as a general term for solid electrolytes that mainly contain raw materials such as Li. ２ S-P ２ S ５ The compounds include Li ２ S and P ２ S ５ and further includes a solid electrolyte containing other raw materials. ２ S-P ２ S ５ The compounds include Li ２ S and P ２ S ５ The solid electrolyte also includes a mixture ratio of different.

[0056] Li ２ S-P ２ S ５ Li-based compounds include ２ S-P ２ S ５ , Li ２ S-P ２ S ５ - LiI, Li ２ S-P ２ S ５ -LiCl, Li ２ S-P ２ S ５ - LiBr, Li ２ S-P ２ S ５ -Li ２ O, Li ２ S-P ２ S ５ -Li ２ O-LiI, Li ２ S-P ２ S ５ -Z ｍ S ｎ (m and n are positive numbers, and Z is Ge, Zn, or Ga).

[0057] Li ２ S-SiS ２ Li-based compounds include ２ S-SiS ２ , Li ２ S-SiS ２ - LiI, Li ２ S-SiS ２ - LiBr, Li ２ S-SiS ２ -LiCl, Li ２ S-SiS ２ -B ２ S ３ - LiI, Li ２ S-SiS ２ -P ２ S ５ - LiI, Li ２ S-SiS ２ -Li ３ P.O. ４ , Li ２ S-SiS ２ -Li ２ SO ４ , Li２ S-SiS ２ -Li ｘ MO ｙ (x and y are positive numbers; M is P, Si, Ge, B, Al, Ga, or In).

[0058] Li ２ S-GeS ２ Li-based compounds include ２ S-GeS ２ , Li ２ S-GeS ２ -P ２ S ５ Examples include:

[0059] The sulfide-based solid electrolyte may be a crystalline material or an amorphous material.

[0060] (Hydride-based solid electrolyte) As the hydride-based solid electrolyte material, LiBH ４ , LiBH ４ -3KI, LiBH ４ -PI ２ , LiBH ４ -P ２ S ５ , LiBH ４ -LiNH ２ , 3LiBH ４ - LiI, LiNH ２ , Li ２ AlH ６ , Li(NH ２ ) ２ I, Li ２ NH, LiGd(BH ４ ) ３ Cl, Li ２ (BH ４ ) (NH ２ ), Li ３ (NH ２ ) I, Li ４ (BH ４ ) (NH ２ ) ３ Examples include:

[0061] Examples of the second solid electrolyte material include compounds in which part or all of the Li in the compounds listed as specific examples of oxide-based solid electrolytes, sulfide-based solid electrolytes, or hydride-based solid electrolytes is replaced with Na, K, Rb, or Cs.

[0062] The second electrolyte layer is formed from a second electrolyte composition. The second electrolyte layer may contain a material different from that of the first electrolyte layer. The second electrolyte composition may contain a solid electrolyte material and, as necessary, a polymer electrolyte, a binder resin, an organic solvent, an ionic liquid, etc. The solid electrolyte material may contain at least one of the first solid electrolyte material and the second solid electrolyte material described above, or may contain the second solid electrolyte material, or may contain at least one of a sulfide-based solid electrolyte and an oxide-based solid electrolyte.

[0063] The thickness ratio between the first electrolyte layer and the second electrolyte layer ((thickness of the first electrolyte layer):(thickness of the second electrolyte layer)) may be 1:0.2 to 1:1, may be 1:0.3 to 1:1, or may be 1:0.5 to 1:1. By providing the first electrolyte layer and the second electrolyte layer, interfaces that enable good ion conduction are formed at the interface between the positive electrode and the first electrolyte layer and the interface between the negative electrode and the second electrolyte layer. In addition, ion conduction between the first electrolyte layer and the second electrolyte layer is also good. As a result, a battery capable of good charge and discharge is obtained. This is due to the characteristic of the first electrolyte layer having small impedance distortion (mechanically, due to the characteristic of being flexible and easily forming a good interface). In addition, because the first electrolyte layer has the characteristic of having small distortion and flexibility, cracks are less likely to occur inside the battery, which also contributes to obtaining good charge and discharge characteristics in that the ion conduction path is less likely to be broken.

[0064] The first electrolyte layer may have a region within 20 μm of the interface between the positive electrode layer and the first electrolyte layer in the vertical direction (normal direction) and free from microcracks exceeding 10 μm in size. The region may have a void structure.

[0065] The battery may have a separator. The separator may be a porous material, such as a porous resin material. Specific examples of the separator include a porous polyolefin membrane and a porous ceramic membrane.

[0066] The method for manufacturing the battery of this embodiment is not particularly limited, and may include a step of pressurizing a positive electrode material to manufacture a positive electrode and a step of pressurizing a first electrolyte composition to manufacture a first electrolyte layer. The step of pressurizing a positive electrode material to manufacture a positive electrode and the step of pressurizing a first electrolyte composition to manufacture a first electrolyte may be performed simultaneously. In this case, the first electrolyte composition is disposed on the positive electrode material, and both are pressurized to manufacture a positive electrode and a first electrolyte layer. The second electrolyte layer may be formed by disposing a second electrolyte composition on the first electrolyte layer and applying pressure. The negative electrode may be formed by disposing a negative electrode on the second electrolyte layer, or by disposing a negative electrode material and applying pressure.

[0067] <Preparation of Solid Electrolyte Material> (Example 1) In an argon atmosphere having a dew point of −70° C. or less (hereinafter referred to as a dry argon atmosphere), LiCl, ZrCl ４ A raw material was prepared by mixing LiBr and LiFePO4 in a molar ratio of 1.5:1:0.5. The raw material was placed in a zirconia pot for a planetary ball mill, and 65 g of zirconia balls with a diameter of 4 mm were added. The mixture was treated in a planetary ball mill (PM 400, manufactured by Verder Scientific K.K.) for 48 hours at 380 rpm to undergo a mechanochemical reaction, thereby obtaining a solid electrolyte material (Li ２ ZrCl ５．５ Br ０．５ The ball mill was operated in a mode in which the rotation direction was alternately switched between clockwise and counterclockwise, with a 1-minute interval between rotations of 10 minutes.

[0068] <Preparation of Secondary Battery> The solid electrolyte material of Example 1 and LiNi １／３ Mn １／３ Co １／３ O ２29 parts by mass, 67 parts by mass, and 4 parts by mass of acetylene black were weighed out and mixed in a mortar to obtain a mixture. 100 mg of the solid electrolyte material of Example 1 and 15 mg of the above mixture were stacked in this order in an insulating tube with an inner diameter of 10 mm to obtain a laminate. A pressure of 200 MPa was applied to the laminate to form a first electrode (a layer of the above mixture) and a first solid electrolyte layer (a layer of the solid electrolyte material of Example 1, 0.5 mm). Next, a sulfide solid electrolyte Li ６ P.S. ５ 60 mg of Cl was placed in contact with the first electrode to obtain a laminate. A pressure of 200 MPa was applied to the laminate, forming a second solid electrolyte layer (0.3 mm). The first solid electrolyte layer was sandwiched between the first electrode and the second solid electrolyte layer. Next, 60 mg of In foil was placed in contact with the second solid electrolyte layer, and 2 mg of Li foil was placed in contact with the In foil to obtain a laminate. A pressure of 200 MPa was applied to the laminate, forming a second electrode. Stainless steel current collectors were attached to the first and second electrodes, and then lead wires were attached to the current collectors. All components were placed in a desiccator and sealed, and the secondary battery of Example 1 was thus obtained.

[0069] <Charge / Discharge Test> The following charge / discharge tester was used: Charge / discharge tester: Toyo System Co., Ltd. TOSCAT-3100 At 60°C, the secondary battery was charged at 0.1 C (0.19 mA / cm ２ ), 1C (1.9mA / cm ２ ) and 3C (5.8mA / cm ２ ) and three different C rates. Charging was performed at a constant current and constant voltage (CCCV charging) at a current density corresponding to each C rate up to 3.7 V. Discharging was performed at a current density corresponding to each C rate up to 1.9 V. FIG. 1 shows the results of the charge and discharge test of the secondary battery of Example 1.

[0070] Example 2: LiCl and ZrCl ４ In the same manner as in Example 1, except that the raw materials were prepared by mixing the above in a molar ratio of 3:1, a solid electrolyte material (Li ２ ZrCl６ 2 shows the results of the charge-discharge test of the secondary battery of Example 2.

[0071] Example 3: In an argon atmosphere having a dew point of −70° C. or less (hereinafter referred to as a dry argon atmosphere), LiCl, ZrCl ４ , BiCl ３ , ZnCl ２ and LiBr to Li ２．０５ Zr ０．９６ Bi ０．０３ Zn ０．０１ Cl ５．７ Br ０．３ The raw materials were mixed to obtain a charge composition of 1.2 g. 1.2 g of the raw materials were placed in a zirconia pot for a planetary ball mill, and 55 g of 4 mm diameter zirconia balls and 15 g of 8 mm diameter zirconia balls were added. Using the planetary ball mill, the ball milling process was carried out in this order at 300 rpm for 8 hours, 350 rpm for 8 hours, and 320 rpm for 8 hours, resulting in a mechanochemical reaction, thereby obtaining a solid electrolyte material. The ball mill was operated in a mode in which the rotation direction was alternately switched between clockwise and counterclockwise, stopping for 1 minute every 10 minutes of rotation.

[0072] Example 4 In an argon atmosphere having a dew point of −70° C. or less (hereinafter referred to as a dry argon atmosphere), ２ O, Li ３ P.O. ４ , ZrCl ４ , MgCl ２ , Li ２ Zr ０．９５ Mg ０．０５ Cl ３．９ O (PO ４ ) ０．０３３ The synthesis was carried out under the same conditions as in Example 3, except that the raw materials were mixed to obtain the composition shown below.

[0073] <Observation of Particles with a Scanning Electron Microscope (SEM)> Observation was carried out using a scanning electron microscope JCM-7000 (manufactured by JEOL Ltd.) Observation of particles of the solid electrolyte material produced under conditions of an acceleration voltage of 15 kV and high vacuum mode was carried out.

[0074] <Measurement of Resistance> In a dry argon atmosphere, the solid electrolyte material of Example 3 and LiNi １／３ Mn １／３ Co １／３ O ２ A mixture was obtained by weighing 29 parts by mass, 67 parts by mass, and 4 parts by mass of acetylene black, respectively, and mixing them in a mortar. A laminate was obtained by sequentially stacking 100 mg of the solid electrolyte material of Example 3 and 15 mg of the above mixture in an insulating tube with an inner diameter of 10 mm. A pressure of 200 MPa was applied to the laminate, forming a first electrode (a layer of the above mixture) and a first solid electrolyte layer (a layer of the solid electrolyte material of Example 3, 0.5 mm). The laminate was sandwiched between two SUS plates. Each was electrically connected to the terminal of an impedance analyzer (S11260, manufactured by Solatron Analytical). The resistance value was 274 Ω. Similarly, a laminate was prepared in the same manner as in Example 3, except that the solid electrolyte material of Example 4 was used instead of the solid electrolyte material of Example 3, and impedance measurements were performed.

[0075] A Cole-Cole diagram (Nyquist plot) was created from the impedance measurement results. In the Cole-Cole diagram, the real value of the impedance at the measurement point where the absolute value of the phase of the complex impedance was smallest was considered to be the resistance value. Table 1 also summarizes the frequency at which the phase angle is smallest in the Nyquist plot obtained by performing impedance measurements in the range of 0.1 Hz to 891 kHz, and the ratio A / B of the resistance value (A) of the impedance measurement to the resistance value (B) of the real part of the impedance at 891 kHz.

[0076] Comparative Example 1: LiCl and YCl were used as raw materials. ３ In the same manner as in Example 1, a solid electrolyte material (Li ３ YCl ６ Using the obtained solid electrolyte material, the cross section of the solid electrolyte material and the laminate were observed with a scanning electron microscope, and the impedance of the laminate was measured in the same manner as in Example 3. The resistance value was 2400 Ω.

[0077]

[0078] <Cross-section observation by scanning electron microscope (SEM)> Observation was performed using a scanning electron microscope JCM-7000 (manufactured by JEOL Ltd.). Observation was performed under conditions of an acceleration voltage of 15 kV and high vacuum mode. As a measurement sample, the laminate produced in the pressure molding die as described above was removed, cut in the thickness direction, and the cross section was observed.

[0079] Figure 3 is a scanning electron microscope image of particles of the solid electrolyte material of Example 3. Figure 4 is an enlarged view of a portion of the particle in Figure 3. As can be seen from Figures 3 and 4, the particles of the solid electrolyte material of Example 1 had an uneven structure with a size of 0.5 to 2 μm. Furthermore, Figure 5 is a scanning electron microscope image of a cross section of the laminate of Example 1. As shown in Figure 5, although voids with a diameter of about 2 to 5 μm were observed, no large microcracks were observed in either the positive electrode layer or the solid electrolyte layer.

[0080] FIG. 6 is a scanning electron microscope image of particles of the solid electrolyte material of Comparative Example 1. FIG. 7 is an enlarged view of a portion of the particle in FIG. 6. As can be seen from FIGS. 6 and 7, the particles of Comparative Example 1 did not have a clear uneven structure, and microcracks were observed in the area surrounded by a square in FIG. 7. FIG. 8 is a scanning electron microscope image of the cross section of the laminate of Comparative Example 1. As shown in FIG. 8, although voids of about 2 to 5 μm in diameter were observed, many microcracks were observed in both the positive electrode layer and the solid electrolyte layer, and the microcracks in the solid electrolyte layer were longer than 10 μm (the area surrounded by a square in FIG. 8). FIG. 9 shows Nyquist plots of the laminate of Example 3 and the laminate of Comparative Example 1.

Claims

1. It comprises a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode, The electrolyte layer includes a first electrolyte layer and a second electrolyte layer. The first electrolyte layer is disposed between the positive electrode and the second electrolyte layer. The first electrolyte layer comprises a different material from the second electrolyte layer. The first electrolyte layer comprises a solid electrolyte material containing an alkali metal element, a metal element other than an alkali metal element or a metalloid element, and a halogen element. The metal elements or metalloid elements other than the alkali metal elements include at least one of Zr and In. A battery in which a Nyquist plot is obtained by sandwiching a laminate consisting of the positive electrode and the first electrolyte layer between two SUS plates and measuring the impedance in the range of 0.1 Hz to 891 kHz, the frequency at which the phase angle is smallest is 100 kHz to 891 kHz, and the ratio A / B of the real part resistance value of the impedance measurement at the frequency at which the phase angle is smallest (A) to the real part resistance value of the impedance at 891 kHz (B) is 1.0 to 3.

5.

2. It comprises a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode, The electrolyte layer includes a first electrolyte layer and a second electrolyte layer. The first electrolyte layer is disposed between the positive electrode and the second electrolyte layer. The first electrolyte layer comprises a different material from the second electrolyte layer. The first electrolyte layer comprises a solid electrolyte material containing an alkali metal element, a metal element other than an alkali metal element or a metalloid element, and a halogen element. The metal elements or metalloid elements other than the alkali metal elements include at least one of Zr and In. A battery in which the second electrolyte layer includes at least one of an oxide-based solid electrolyte and a sulfide-based solid electrolyte.

3. It comprises a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode, The electrolyte layer includes a first electrolyte layer and a second electrolyte layer. The first electrolyte layer is disposed between the positive electrode and the second electrolyte layer. The first electrolyte layer comprises a different material from the second electrolyte layer. The first electrolyte layer comprises a solid electrolyte material containing an alkali metal element, a metal element other than an alkali metal element or a metalloid element, and a halogen element. The metal elements or metalloid elements other than the alkali metal elements include at least one of Zr and In. A battery in which the thickness ratio of the first electrolyte layer to the second electrolyte layer is 1:0.2 to 1:

1.

4. It comprises a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode, The electrolyte layer includes a first electrolyte layer and a second electrolyte layer. The first electrolyte layer is disposed between the positive electrode and the second electrolyte layer. The first electrolyte layer comprises a different material from the second electrolyte layer. The first electrolyte layer comprises a solid electrolyte material containing an alkali metal element, a metal element other than an alkali metal element or a metalloid element, and a halogen element. The metal elements or metalloid elements other than the alkali metal elements include at least one of Zr and In. The first electrolyte layer further contains an ionic liquid, forming a battery.

5. The solid electrolyte material is A α M β Z γ D ζ O η It contains a compound represented by, A battery according to any one of claims 1 to 4, wherein A is an alkali metal element, M is a metal element or metalloid element other than an alkali metal element, Z is a halogen element, D is at least one of P and S, and 1.6 ≤ α ≤ 3.5, 0 < β ≤ 1.2, 3 ≤ γ ≤ 6.5, 0 ≤ ζ ≤ 0.5, and 0 ≤ η ≤ 2.

6. The battery according to any one of claims 1 to 4, wherein the positive electrode comprises a solid electrolyte material containing an alkali metal element, a metal element or metalloid element other than an alkali metal element, and a halogen element.

7. The device comprises a positive electrode and an electrolyte layer disposed on the positive electrode, The electrolyte layer includes a first electrolyte layer and a second electrolyte layer. The first electrolyte layer is disposed between the positive electrode and the second electrolyte layer. The first electrolyte layer comprises a different material from the second electrolyte layer. The first electrolyte layer comprises a solid electrolyte material containing an alkali metal element, a metal element other than an alkali metal element or a metalloid element, and a halogen element. The metal elements or metalloid elements other than the alkali metal elements include at least one of Zr and In. A laminate comprising the positive electrode and the first electrolyte layer, sandwiched between two SUS plates, and subjected to impedance measurements in the range of 0.1 Hz to 891 kHz, the Nyquist plot obtained has the smallest phase angle at a frequency of 100 kHz to 891 kHz, and the ratio A / B of the real part resistance value (A) of the impedance measurement at the frequency with the smallest phase angle to the real part resistance value (B) of the impedance at 891 kHz is 1.0 to 3.

5.

8. The device comprises a positive electrode and an electrolyte layer disposed on the positive electrode, The electrolyte layer includes a first electrolyte layer and a second electrolyte layer. The first electrolyte layer is disposed between the positive electrode and the second electrolyte layer. The first electrolyte layer comprises a different material from the second electrolyte layer. The first electrolyte layer comprises a solid electrolyte material containing an alkali metal element, a metal element other than an alkali metal element or a metalloid element, and a halogen element. The metal elements or metalloid elements other than the alkali metal elements include at least one of Zr and In. The second electrolyte layer is a laminate comprising at least one of an oxide-based solid electrolyte and a sulfide-based solid electrolyte.

9. The device comprises a positive electrode and an electrolyte layer disposed on the positive electrode, The electrolyte layer includes a first electrolyte layer and a second electrolyte layer. The first electrolyte layer is disposed between the positive electrode and the second electrolyte layer. The first electrolyte layer comprises a different material from the second electrolyte layer. The first electrolyte layer comprises a solid electrolyte material containing an alkali metal element, a metal element other than an alkali metal element or a metalloid element, and a halogen element. The metal elements or metalloid elements other than the alkali metal elements include at least one of Zr and In. A laminate in which the thickness ratio of the first electrolyte layer to the second electrolyte layer is 1:0.2 to 1:

1.

10. The device comprises a positive electrode and an electrolyte layer disposed on the positive electrode, The electrolyte layer includes a first electrolyte layer and a second electrolyte layer. The first electrolyte layer is disposed between the positive electrode and the second electrolyte layer. The first electrolyte layer comprises a different material from the second electrolyte layer. The first electrolyte layer comprises a solid electrolyte material containing an alkali metal element, a metal element other than an alkali metal element or a metalloid element, and a halogen element. The metal elements or metalloid elements other than the alkali metal elements include at least one of Zr and In. The first electrolyte layer is a laminate containing an ionic liquid.

11. The solid electrolyte material comprises a compound represented by A α M β Z γ D ζ O η, The laminate according to any one of claims 7 to 10, wherein A is an alkali metal element, M is a metal element or metalloid other than an alkali metal element, Z is a halogen element, D is at least one of P and S, and 1.6 ≤ α ≤ 3.5, 0 < β ≤ 1.2, 3 ≤ γ ≤ 6.5, 0 ≤ ζ ≤ 0.5, and 0 ≤ η ≤ 2.

12. The laminate according to any one of claims 7 to 10, wherein the positive electrode comprises a solid electrolyte material containing an alkali metal element, a metal element or metalloid element other than an alkali metal element, and a halogen element.