battery

Abstract

This invention relates to batteries. Batteries using a positive electrode composite material containing a sulfur-based positive electrode active material have potential for improved cycle characteristics. The battery of this invention comprises a positive electrode composite material layer, an electrolyte layer, and a negative electrode. The positive electrode composite material layer comprises a sulfur-based active material, a phosphorus-containing sulfide, and carbon. The carbon has a BET specific surface area of ​​350 m². 2 / g or more. The molar ratio of P to S in the positive electrode composite material layer is greater than 0.06 and less than 0.24.

Description

Technical Field

[0001] This application discloses a battery. Background Technology

[0002] Patent document 1 discloses a battery using a positive electrode composite material containing a sulfur-based positive electrode active material.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-212615 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] Batteries using cathode composite materials containing sulfur-based cathode active materials have room for improvement in cycle characteristics.

[0008] Methods for solving problems

[0009] As a method for solving the above problems, this application discloses the following multiple methods.

[0010] <Method 1>

[0011] A battery comprising a positive electrode composite material layer, an electrolyte layer, and a negative electrode, wherein the positive electrode composite material layer comprises a sulfur-based active material, a phosphorus-containing sulfide, and carbon, and the carbon has a BET specific surface area of ​​350 m². 2 / g or more, the molar ratio of P to S in the above-mentioned positive electrode composite material layer is greater than 0.06 and less than 0.24.

[0012] <Method 2>

[0013] According to the battery of method 1, the carbon mentioned above is carbon nanotubes.

[0014] <Method 3>

[0015] According to the battery of method 1 or 2, the BET specific surface area of ​​the aforementioned carbon is 1000 m². 2 / g or more.

[0016] <Method 4>

[0017] According to any one of methods 1 to 3, the electrolyte layer comprises a solid electrolyte.

[0018] <Method 5>

[0019] According to any one of the methods 1 to 4, the negative electrode is accompanied by the deposition of metallic lithium during charging and the dissolution of metallic lithium during discharging.

[0020] Invention Effects

[0021] The battery of the present invention has excellent cycle characteristics. Attached Figure Description

[0022] Figure 1 This is a simplified illustration of an example of battery construction.

[0023] Figure 2 The configuration of the compressed battery cells in the comparative examples and embodiments is shown in a schematic manner. Detailed Implementation

[0024] Hereinafter, one embodiment of the battery of the present invention will be described, but the battery of the present invention is not limited to the embodiment described below.

[0025] 1. Battery

[0026] like Figure 1 As shown, a battery 100 according to one embodiment includes a positive electrode composite material layer 11, an electrolyte layer 20, and a negative electrode 30. The positive electrode composite material layer 11 comprises a sulfur-based active material, a phosphorus-containing sulfide, and carbon. The carbon has a BET specific surface area of ​​350 m². 2 / g or more. The molar ratio of P to S in the above-mentioned positive electrode composite material layer 11 is greater than 0.06 and less than 0.24.

[0027] 1.1 Positive electrode

[0028] like Figure 1 As shown, the positive electrode 10 of the battery 100 may, for example, include a positive electrode composite material layer 11 and a positive electrode current collector 12 in contact with the positive electrode composite material layer 11. The positive electrode composite material layer 11 may be formed on the surface of the positive electrode current collector 12.

[0029] 1.1.1 Positive electrode composite material layer

[0030] The positive electrode composite layer 11 comprises a sulfur-based active material, a phosphorus-containing sulfide, and carbon. In addition to the sulfur-based active material, phosphorus-containing sulfide, and carbon, the positive electrode composite layer 11 may also contain one or more of other active materials, other electrolytes, other conductive materials, and binders. By including a sulfur-based active material and a phosphorus-containing sulfide in the positive electrode composite layer 11 and satisfying a specified molar ratio P / S, the ionic conductivity of the positive electrode composite layer 11 is improved. Furthermore, by including a sulfur-based active material and carbon in the positive electrode composite layer 11 and having a BET specific surface area of ​​carbon of a specified value or higher, the electronic conductivity of the positive electrode composite layer 11 is improved. As a result, the utilization rate of the sulfur-based active material in the positive electrode composite layer 11 is improved, and the cycle characteristics of the battery are easily improved.

[0031] 1.1.1.1 Sulfur-based active substances

[0032] The sulfur-based active material contained in the positive electrode composite layer 11 only needs to react with Li ions (which act as charge compensation ions) during discharge to generate compounds containing sulfur and lithium (such as sulfides like Li₂S) as discharge products, and be able to release Li ions during charging. The sulfur-based active material can contain elemental sulfur or be composed entirely of elemental sulfur. Elemental sulfur can be octasulfide (S₈) or other elemental sulfur. Octasulfide (S₈) can be α-sulfur, β-sulfur, γ-sulfur, or a combination thereof. The sulfur-based active material contained in the positive electrode composite layer 11 can be dissolved in solid solution with P-containing sulfides (described later) or chemically bonded to P-containing sulfides. For example, the S in the sulfur-based active material can chemically bond with the S in the P-containing sulfide. The shape of the sulfur-based active material contained in the positive electrode composite layer 11 is not particularly limited; for example, it can be particulate or amorphous. Whether the cathode composite layer 11 contains sulfur-based active materials can be determined by performing various analyses such as XAFS, XRD, and NMR on the cathode composite material constituting the cathode composite layer 11. For example, when the cathode composite layer 11 is composed of a cathode composite material containing elemental sulfur, when an X-ray diffraction pattern is obtained for this cathode composite material using CuKα as the X-ray source, diffraction peaks originating from elemental sulfur are confirmed in the X-ray diffraction pattern. Diffraction peaks originating from elemental sulfur typically appear at 2θ = 23.05°±0.50°, 25.84°±0.50°, and 27.70°±0.50°.

[0033] The amount of sulfur-based active material contained in the cathode composite material layer 11 is not particularly limited, and can be appropriately determined according to the target battery performance. In one embodiment, the content of sulfur-based active material in the cathode composite material layer 11 can be more than 20% by mass and less than 70% by mass, or more than 30% by mass and less than 60% by mass.

[0034] 1.1.1.2 P-containing sulfides

[0035] The P-containing sulfide contained in the positive electrode composite layer 11 contains at least P and S as constituent elements, and may further contain other elements M. Examples of other elements M include one or more of Ge, Sn, Si, B, and Al. Alternatively, the P-containing sulfide may contain P, S, and optional element M as constituent elements, but not Li. The P-containing sulfide may contain sulfides that are compounds of P and S (e.g., P2S5). Furthermore, the P-containing sulfide may have a positive P structure (PS4 structure). Additionally, the P-containing sulfide may combine with the aforementioned sulfur-based active materials to undergo amorphization, such as P2S6. 4- P2S7 4-The form of the P-containing sulfide in the cathode composite layer 11 is not particularly limited; for example, it can be granular or amorphous. Whether the cathode composite layer 11 contains P-containing sulfides can be determined by performing various analyses such as XAFS, XRD, and NMR on the cathode composite material constituting the cathode composite layer 11. For example, when the cathode composite layer 11 is composed of a composite material containing P2S5, when an X-ray diffraction pattern is obtained for this composite material using CuKα as the X-ray source, diffraction peaks originating from P2S5 are identified in the X-ray diffraction pattern. Diffraction peaks originating from P2S5 typically appear at 2θ = 25.84° ± 0.50°, 30.35° ± 0.50°, and 31.32° ± 0.50°. Furthermore, when the cathode composite material is measured using XAFS, peaks originating from P2S5 are identified. Furthermore, when the cathode composite material is measured using NMR, peaks originating from P2S5 are identified.

[0036] The molar ratio (P / S) of phosphorus (P) to sulfur (S) in the cathode composite layer 11 is greater than 0.06 and less than 0.24. Therefore, the cathode composite layer 11 readily exhibits high ionic conductivity. This molar ratio (P / S) can be 0.07 or higher, 0.08 or higher, 0.09 or higher, 0.10 or higher, 0.11 or higher, 0.12 or higher, 0.13 or higher, 0.14 or higher, or 0.15 or higher, and can be less than 0.23, less than 0.22, less than 0.21, less than 0.20, less than 0.19, or less than 0.18. In one embodiment, this molar ratio (P / S) can be 0.10 or higher and less than 0.21, or 0.15 or higher and less than 0.20. Here, the denominator of the molar ratio (P / S) refers to the total amount of sulfur (S) contained in the cathode composite layer 11. In the case where the positive electrode composite layer 11 contains sulfur-based active materials, P-containing sulfides and other sulfides described later, since they all contain S element, the total amount of these S elements is used as the denominator of the molar ratio P / S.

[0037] The amount of P-containing sulfides contained in the positive electrode composite material layer 11 can be appropriately determined according to the target battery performance within the range of the above-mentioned molar ratio P / S. In one embodiment, the content of P-containing sulfides in the positive electrode composite material layer 11 can be 20% by mass or more and 70% by mass or less, or 30% by mass or more and 60% by mass or less.

[0038] 1.1.1.2 Carbon

[0039] The carbon contained in the cathode composite layer 11 only needs to have a specified or higher BET specific surface area. This carbon can be, for example, carbon nanotubes, porous carbon such as activated carbon, or a combination thereof. Especially when the carbon contained in the cathode composite layer 11 is carbon nanotubes, high performance is easily ensured as a battery. The carbon nanotubes can be single-layer carbon nanotubes, multi-layer carbon nanotubes, or a combination thereof. Especially when using single-layer carbon nanotubes, higher performance is easily ensured as a battery. The diameter (outer diameter) of the single-layer carbon nanotubes can be, for example, less than 4 nm, or more than 1 nm and less than 3 nm. Conversely, the diameter (outer diameter) of the multi-layer carbon nanotubes can be, for example, greater than 4 nm, or more than 5 nm or more than 10 nm. The aspect ratio (length / outer diameter) of the carbon nanotubes is not particularly limited. Whether the cathode composite layer 11 contains carbon nanotubes can be determined, for example, by observation of the cathode composite layer 11 using SEM or the like, and by elemental analysis of the cathode composite layer 11.

[0040] The BET specific surface area of ​​the carbon contained in the positive electrode composite layer 11 is 350 m². 2 / g or more. The cathode composite layer 11, containing carbon with such a high specific surface area, exhibits high electronic conductivity. The BET specific surface area of ​​the carbon contained in the cathode composite layer 11 can be 400 m². 2 / g or more, 450m 2 / g or more, 500m 2 / g or more, 550m 2 / g or more, 600m 2 / g or more, 650m 2 / g or more, 700m 2 / g or more, 750m 2 / g or more, 800m 2 / g or more, 850m 2 / g or more, 900m 2 / g or more, 950m 2 / g or more, 1000m 2 / g or more, 1050m 2 / g or more, 1100m 2 / g or more or 1150m 2 / g or more. There is no specific upper limit to the BET specific surface area. For example, the BET specific surface area could be 2000 m². 2 / g or less, 1900m 2 / g or less, 1800m 2 / g or less, 1700m 2 / g or less, 1600m 2 / g or less, 1550m 2 / g or less, 1500m2 / g or less, 1450m 2 / g or less, 1400m 2 / g or less, 1350m 2 / g or less, 1300m 2 / g or less, 1250m 2 / g or less or 1200m 2 / g or less. In one embodiment, the BET specific surface area of ​​the carbon contained in the positive electrode composite layer 11 can be 1000m². 2 / g or more and 1600m 2 / g or less, or 1100m 2 / g or more and 1550m 2 / g or less. It should be noted that the BET specific surface area of ​​the carbon contained in the positive electrode composite layer 11 can be determined by the BET method using nitrogen as the adsorbed gas. Specifically, after the carbon used in the positive electrode composite layer 11 is vacuum dried at 120°C for 12 hours, the BET specific surface area (m²) of the carbon is measured, for example, according to JIS Z8830:2013, using a specific surface area measuring device (BERSORP-MAX (MicrotracBEL Co., Ltd.)). 2 / g).

[0041] The amount of carbon contained in the positive electrode composite material layer 11 is not particularly limited, and can be appropriately determined according to the target battery performance. In one embodiment, the carbon content in the positive electrode composite material layer 11 can be 10% by mass or more and 40% by mass or less, or 15% by mass or more and 30% by mass or less.

[0042] 1.1.1.4 Other components

[0043] The positive electrode composite layer 11 may contain other active materials, other sulfides, other conductive materials, binders, and other components. The content of these other components in the positive electrode composite layer 11 is not particularly limited. Other active materials may be, for example, various lithium-containing compounds. These lithium-containing compounds may be lithium cobalt oxide, lithium nickel oxide, or Lithium oxide. 1±α Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O 2±δ Lithium manganese oxide, spinel-based lithium compounds (Li 1+x Mn 2-x-y M yVarious lithium oxides, such as lithium titanate and lithium metal phosphate (LiMPO4, etc., where M is selected from one or more of Al, Mg, Co, Fe, Ni, and Zn), are used. It should be noted that the higher the proportion of sulfide active material in the overall positive electrode active material, the more easily the expansion and contraction of the positive electrode composite layer 11 during charging and discharging becomes, and the more easily the cycle characteristics decrease. However, according to this embodiment, by satisfying the above-mentioned molar ratio P / S and BET specific surface area, the cycle characteristics can be easily improved. Regarding this, the proportion of sulfide active material in the overall active material contained in the positive electrode composite layer can be 50% by mass or more and 100% by mass or less, 70% by mass or more and 100% by mass or less, 90% by mass or more and 100% by mass or less, or 95% by mass or more and 100% by mass or less. Other sulfides may contain at least element M (M being one or more of Ge, Sn, Si, B, and Al) and S as constituent elements. Other sulfides may also contain a normal structure of element M. Examples of normal structures of element M include one or more of GeS4, SnS4, SiS4, BS3, and AlS3 structures. Additionally, other sulfides may contain sulfides that are compounds of elements M and S (M... x S y Here, x and y are integers assigned electrical neutrality to S according to the kind of M. As M x S y For example, one or more of GeS2, SnS2, SiS2, B2S3, and Al2S3 can be listed. Other conductive materials can include various carbon or metal materials other than carbon nanotubes. In the positive electrode composite material layer 11, the conductive material can contain only carbon or only carbon nanotubes. The binder can be, for example, one or more selected from butadiene rubber (BR) based binders, butene rubber (IIR) based binders, acrylate butadiene rubber (ABR) based binders, styrene butadiene rubber (SBR) based binders, polyvinylidene fluoride (PVdF) based binders, polytetrafluoroethylene (PTFE) based binders, and polyimide (PI) based binders.

[0044] The shape and thickness of the positive electrode composite layer 11 are not particularly limited, and can be appropriately determined by considering the target battery performance. The positive electrode composite layer 11 can be a sheet with a generally flat surface. The thickness of the positive electrode composite layer 11 can be, for example, 0.1 μm or more, 1 μm or more, 10 μm or more, or 30 μm or more, and can be less than 2 mm, less than 1 mm, less than 500 μm, or less than 100 μm.

[0045] 1.1.2 Positive Current Collector

[0046] like Figure 1 As shown, the positive electrode 10 of the battery 100 may have a positive electrode current collector 12 in contact with the positive electrode composite material layer 11. The constituent material, shape, and size of the positive electrode current collector 12 are not particularly limited. The positive electrode current collector 12 may be, for example, foil or plate-shaped. The positive electrode current collector 12 may be a metal foil. Alternatively, the positive electrode current collector 12 may have a layer formed of a resin composition comprising a resin and a conductive material. Alternatively, the positive electrode current collector 12 may comprise a combination of a metal foil and a layer formed of a resin composition. The positive electrode current collector 12 may be composed of two or more foils or sheets. As the metal constituting the metal foil serving as the positive electrode current collector 12, at least one selected from Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, V, Mg, Pb, Ge, In, Sn, Zr, and stainless steel may be included. Particularly from the viewpoint of ensuring oxidation resistance, the positive electrode current collector 12 may contain Al. The positive current collector 12 can be a positive current collector on which the aforementioned metal is plated or vapor-deposited onto a metal foil or substrate. Furthermore, when the positive current collector 12 is composed of two or more metal foils, a layer may be formed between the two or more metal foils. The thickness of the positive current collector 12 is not particularly limited. For example, the thickness of the positive current collector 12 can be 1 μm or more and 1 mm or less.

[0047] 1.2 Electrolyte Layer

[0048] like Figure 1As shown, the electrolyte layer 20 is disposed between the positive electrode composite layer 11 and the negative electrode 30. The electrolyte layer 20 contains at least an electrolyte. The electrolyte layer 20 may contain at least one of a solid electrolyte and a liquid electrolyte (electrolyte), and may optionally further contain a binder, etc. In particular, when the electrolyte layer 20 contains a solid electrolyte, it is easy to ensure higher performance. The electrolyte layer 20 may be a solid electrolyte layer without liquid electrolyte. According to the technology of the present invention, the utilization rate of the sulfur-based active material in the positive electrode composite layer 11 can be improved, local expansion of the positive electrode composite layer 11 during battery charging and discharging can be suppressed, and cracking of the solid electrolyte layer is less likely to occur. Alternatively, the electrolyte layer 20 may also have a separator, etc., for holding the liquid electrolyte and preventing contact between the positive electrode composite layer 11 and the negative electrode 30. The thickness of the electrolyte layer 20 is not particularly limited, for example, it may be 0.1 μm or more or 1 μm or more, or 2 mm or less or 1 mm or less. The electrolyte layer 20 may be composed of one layer or two or more layers. For example, the electrolyte layer 20 may have a first layer disposed on the positive electrode composite material layer 11 side and a second layer disposed on the negative electrode 30 side, or the first layer may contain a first electrolyte and the second layer may contain a second electrolyte. The first electrolyte and the second electrolyte may be different types from each other. The first electrolyte and the second electrolyte may each be at least one selected from oxide solid electrolytes, sulfide solid electrolytes, and ion-bound solid electrolytes described later. For example, the first layer may contain an ion-bound solid electrolyte, and the second layer may contain at least one of ion-bound solid electrolytes and sulfide solid electrolytes.

[0049] 1.2.1 Solid Electrolytes

[0050] Solid electrolytes can be inorganic solid electrolytes or organic polymer electrolytes. In particular, inorganic solid electrolytes exhibit excellent ionic conductivity and heat resistance. Examples of inorganic solid electrolytes include oxide solid electrolytes, sulfide solid electrolytes, and ion-bound inorganic solid electrolytes. Among inorganic solid electrolytes, sulfide solid electrolytes, and especially those containing at least Li, S, and P as constituent elements, exhibit high performance. Alternatively, among inorganic solid electrolytes, ion-bound solid electrolytes, and especially those containing at least Li, Y, and a halogen (at least one of Cl, Br, I, and F) as constituent elements, exhibit high performance. Solid electrolytes can be amorphous or crystalline. Solid electrolytes can be in particulate form. The average particle size (D50) of solid electrolytes can, for example, be 10 nm or more and 10 μm or less.

[0051] The oxide solid electrolyte can be selected from lithium lanthanum zirconate, LiPON, Li 1+X Al X Ge 2-XOne or more of the following: (PO4)3, Li-SiO glass, and Li-Al-SO glass. Furthermore, combining oxide solid electrolytes with liquid electrolytes can improve ionic conductivity.

[0052] Sulfide solid electrolytes can be glass-based (sulfide glass), glass-ceramic-based, or crystalline. Sulfide glass is amorphous. Sulfide glass can have a glass transition temperature (Tg). Furthermore, when the sulfide solid electrolyte has a crystalline phase, examples of such crystalline phases include the thio-lithium superionic conductor (Thio-LISICON) type, the LGPS type, and the sulfide-germanium ore type. Sulfide solid electrolytes can be in particulate form. The average particle size (D50) of the sulfide solid electrolyte can be, for example, 10 nm or more and 100 μm or less.

[0053] Sulfide solid electrolytes may contain, for example, Li, X (where X is at least one of P, As, Sb, Si, Ge, Sn, B, Al, Ga, and In), and S. Additionally, sulfide solid electrolytes may also contain at least one of O and a halogen. Furthermore, sulfide solid electrolytes may contain S as the main component of the anionic element.

[0054] Sulfide solid electrolytes can be selected from, for example, Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-GeS2, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-P2S5-LiI-LiBr, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-ZmSn (where m and n are positive numbers, and Z is any one of Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, and Li2S-SiS2-Li x MO y (where x and y are positive numbers, and M is any one of P, Si, Ge, B, Al, Ga, and In).

[0055] The composition of sulfide solid electrolytes is not particularly limited; examples include xLi₂S·(100-x)P₂S₅ (70≤x≤80) and yLiI·zLiBr·(100-yz)(xLi₂S·(1-x)P₂S₅) (0.7≤x≤0.8, 0≤y≤30, 0≤z≤30). Alternatively, sulfide solid electrolytes can also have the general formula: Li 4-x Ge 1-x P x The composition shown in S4 (0 < x < 1) is as follows. In the above general formula, at least a portion of Ge can be substituted with at least one of Sb, Si, Sn, B, Al, Ga, In, Ti, Zr, V, and Nb. In the above general formula, at least a portion of P can be substituted with at least one of Sb, Si, Sn, B, Al, Ga, In, Ti, Zr, V, and Nb. In the above general formula, a portion of Li can be substituted with at least one of Na, K, Mg, Ca, and Zn. In the above general formula, a portion of S can be substituted with at least one halogen (F, Cl, Br, and I). Alternatively, the sulfide solid electrolyte can have Li 7- a PS 6-a X a The composition shown is as follows: (X is at least one of Cl, Br, and I, and a is a number greater than 0 and less than 2). a can be 0 or greater than 0. In the latter case, a can be greater than 0.1, greater than 0.5, or greater than 1. Additionally, a can be less than 1.8 or less than 1.5.

[0056] Ion-bound solid electrolytes may, for example, contain at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Zn, Sn, Al, Sc, Ga, Bi, Sb, Zr, Hf, Ti, Ta, Nb, W, Y, Gd, Tb, and Sm. These elements can generate cations in water. Additionally, ion-bound solid electrolyte materials may also contain at least one halide element selected from the group consisting of Cl, Br, I, and F. These elements can generate anions in water. Ion-bound solid electrolytes may contain at least one element selected from the group consisting of Gd, Ca, Zr, and Y, at least one element selected from the group consisting of Cl, Br, I, and F, and Li. Furthermore, ion-bound solid electrolytes may contain Li and Y, and may contain at least one element selected from the group consisting of Cl, Br, I, and F. More specifically, ion-bound solid electrolytes may contain Li, Y, Cl, and Br, or Li, Ca, Y, Gd, Cl, and Br, or Li, Zr, Y, and Cl. More specifically, ion-bound solid electrolytes can be Li3YBr2Cl4, Li 2.8 Ca 0.1Y 0.5 Gd 0.5 Br2Cl4 and Li 2.5 Y 0.5 Zr 0.5 At least one of Cl6.

[0057] Ion-bound solid electrolytes can be halide solid electrolytes. Halide solid electrolytes exhibit excellent ionic conductivity. Examples of halide solid electrolytes include, for instance, formula (A): Li α M β X γ …(A) shows the composition. Here, α, β, and γ are each independently a value greater than 0, M is at least one selected from the group consisting of metallic elements other than Li and half-metallic elements, and X is at least one selected from the group consisting of Cl, Br, and I. It should be noted that "half-metallic element" can be at least one selected from the group consisting of B, Si, Ge, As, Sb, and Te. In addition, "metallic element" can include (i) all elements contained in Groups 1 to 12 of the periodic table (except hydrogen) and (ii) all elements contained in Groups 13 to 16 of the periodic table (except B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se). Metallic elements can form inorganic compounds with halide ions, and can form cations.

[0058] In formula (A), M may contain Y (i.e., yttrium). Halide solid electrolytes containing Y can have Li a Me b Y c X6 (where a+mb+3c=6, c>0, Me is at least one selected from the group consisting of metallic and half-metallic elements other than Li and Y, and m is the valence of Me) is the composition shown. Me can, for example, be at least one selected from the group consisting of Mg, Ca, Sr, Ba, Zn, Sc, Al, Ga, Bi, Zr, Hf, Ti, Sn, Ta and Nb.

[0059] Halogenated solid electrolytes can have the formula (A1): Li 6-3d Y d The composition shown in X6. In formula (A1), X is one or more elements selected from the group consisting of Cl, Br, and I. d can satisfy 0 < d < 2, or d = 1. Halogen solid electrolytes can have the following composition: Li 3-3δ Y 1+δ The composition shown in Cl6. In formula (A2), 0 < δ ≤ 0.15. Halide solid electrolytes can have formula (A3): Li 3-3δ Y 1+δThe composition shown for Br6. In formula (A3), 0 < δ ≤ 0.25. Halide solid electrolytes can have formula (A4): Li 3-3δ+a Y 1+δ-a Me a Cl 6-x-y Br x I y The composition is shown. In formula (A4), Me can be at least one selected from the group consisting of Mg, Ca, Sr, Ba, and Zn. In formula (A4), for example, -1 < δ < 2, 0 < a < 3, 0 < (3 - 3δ + a), 0 < (1 + δ - a), 0 ≤ x ≤ 6, 0 ≤ y ≤ 6, and (x + y) ≤ 6 are satisfied. Halide solid electrolytes can have formula (A5): Li 3-3δ Y 1+δ-a Me a Cl 6-x-y Br x I y The composition is shown. In formula (A5), Me can be at least one selected from the group consisting of Al, Sc, Ga, and Bi. In formula (A5), it can be -1 < δ < 1, 0 < a < 2, 0 < (1 + δ - a), 0 ≤ x ≤ 6, 0 ≤ y ≤ 6, and (x + y) ≤ 6. The halide solid electrolyte can have formula (A6): Li 3-3δ-a Y 1+δ-a Me a Cl 6-x-y Br x I y The composition is shown. In formula (A6), Me can be at least one selected from the group consisting of Zr, Hf, and Ti. In formula (A6), it can be -1 < δ < 1, 0 < a < 1.5, 0 < (3 - 3δ - a), 0 < (1 + δ - a), 0 ≤ x ≤ 6, 0 ≤ y ≤ 6 and (x + y) ≤ 6. The halide solid electrolyte can have formula (A7): Li 3-3δ-2a Y 1+δ-a Me a Cl 6-x-y Br x I y The composition is shown. In equation (A7), Me can be at least one of the groups consisting of Ta and Nb. In equation (A7), it can be -1 < δ < 1, 0 < a < 1.2, 0 < (3 - 3δ - 2a), 0 < (1 + δ - a), 0 ≤ x ≤ 6, 0 ≤ y ≤ 6 and (x + y) ≤ 6.

[0060] Ion-bound solid electrolytes can be complex hydride solid electrolytes. Complex hydride solid electrolytes can be composed of Li ions and a complex ion containing H. The H-containing complex ion can, for example, have an element M containing at least one of a nonmetallic element, a half-metallic element, and a metallic element, and H bound to that element M. Furthermore, in the H-containing complex ion, the element M as the central element and the H surrounding element M can be covalently bonded together. Alternatively, the H-containing complex ion can also be composed of (M... m H n ) α- This indicates that m is any positive number, and n and α can be any positive numbers depending on m, the valence of element M, etc. Element M can be any nonmetallic or metallic element capable of forming a complex ion. For example, element M can contain at least one of B, C, and N as a nonmetallic element, or it can contain B. Alternatively, element M can contain at least one of Al, Ni, and Fe as a metallic element. Especially when the complex ion contains B, or contains both C and B, it is easier to ensure higher ionic conductivity. A specific example of a complex ion containing H is (CB9H). 10 ) - (CB) 11 H 12 ) - (B) 10 H 10 ) 2- (B) 12 H 12 ) 2- (BH4) - (NH2) - (AlH4) - And their combinations. Especially when using (CB9H) 10 ) - (CB) 11 H 12 ) - In the case of a combination of these, higher ionic conductivity can be easily ensured. That is, complexed hydride solid electrolytes can contain Li, C, B, and H.

[0061] 1.2.2 Liquid Electrolytes

[0062] The liquid electrolyte (electrolyte) is a liquid containing lithium ions as charge carrier ions. The electrolyte can be aqueous or non-aqueous. Its composition should be the same as that known for electrolytes used in lithium-ion batteries. The electrolyte can be an electrolyte in which lithium salts are dissolved in water or a non-aqueous solvent. Examples of non-aqueous solvents include various carbonate solvents. Examples of lithium salts include lithium amide and LiPF6. The separator holding the liquid electrolyte can be any separator commonly used in batteries, such as separators made of resins like polyethylene (PE), polypropylene (PP), polyester, and polyamide. The separator can be a single-layer or multi-layer structure. Examples of multi-layer separators include two-layer PE / PP separators, or three-layer PP / PE / PP or PE / PP / PE separators. The separator can also be made of non-woven fabrics such as cellulose non-woven fabric, resin non-woven fabric, or glass fiber non-woven fabric.

[0063] 1.3.3 Other ingredients

[0064] The binder that may be included in the electrolyte layer 20 may be appropriately selected from the binders exemplified above as binders that may be included in the positive electrode composite layer 11. A single binder may be used, or two or more may be used in combination. The electrolyte layer 20 may contain various additives.

[0065] 1.3 Negative electrode

[0066] like Figure 1 As shown, the negative electrode 30 of the battery 100 may, for example, include a negative electrode active material layer 31 and a negative electrode current collector 32 in contact with the negative electrode active material layer 31. In one embodiment, the negative electrode 30 may be accompanied by the deposition of lithium metal during charging and the dissolution of lithium metal during discharging. In this case, lithium metal is considered to constitute the negative electrode active material layer 31. In addition, in this case, in order to homogenize the deposition and dissolution of lithium metal, an intermediate layer may exist between the electrolyte layer 20 and the negative electrode 30. There is no particular limitation on the type of intermediate layer, which may be a layer containing elements that can alloy with lithium metal.

[0067] 1.3.1 Negative Electrode Active Material Layer

[0068] As described above, the negative electrode active material layer 31 can be accompanied by the deposition and dissolution of metallic lithium. That is, the battery 100 can be configured such that, during charging, metallic lithium is deposited between the electrolyte layer 20 and the negative electrode current collector 32, and during discharging, the metallic lithium between the electrolyte layer 20 and the negative electrode current collector 32 dissolves (ionizes) and returns to the positive electrode. In this case, "metallic lithium" refers to lithium alloys in addition to elemental lithium. That is, in the battery 100, metallic lithium can be deposited in the form of elemental lithium or in an alloy form with other metals. Examples of lithium alloys include Li-Mg, Li-Sn, Li-Al, Li-B, Li-C, Li-Si, Li-Ca, Li-Ga, Li-Ge, Li-As, Li-Se, Li-Ru, Li-Rh, Li-Pd, Li-Ag, Li-Au, Li-Cd, Li-In, Li-Sb, Li-Ir, Li-Pt, Li-Hg, Li-Pb, Li-Bi, Li-Zn, Li-Tl, Li-Te, and Li-At. A single lithium alloy or two or more alloys can be used. The amount of metallic lithium deposited between the electrolyte layer 20 and the negative electrode current collector 32 is not particularly limited and can be adjusted appropriately according to the target battery performance. However, excessive deposited metallic lithium may lead to pressure concentration, etc. In this regard, a target for the amount of metallic lithium deposited could be to achieve a charging capacity of the battery 100 of, for example, 1 mAh / cm³. 2 Above and 5mAh / cm 2 The following quantities.

[0069] Alternatively, the negative electrode active material layer 31 may contain negative electrode active material, and optionally may also contain electrolyte, conductive additives, binders, and various additives. The content of each component in the negative electrode active material layer 31 can be appropriately determined according to the target battery performance. For example, if the solid content of the negative electrode active material layer 31 is set to 100% by mass, the content of the negative electrode active material can be 40% by mass or more, 50% by mass or more, 60% by mass or more, or 70% by mass or more, or it can be less than 100% by mass, less than 100% by mass, less than 95% by mass, or less than 90% by mass. In this case, the shape of the negative electrode active material layer 31 is not particularly limited, for example, it can be a sheet with a generally planar surface. In this case, the thickness of the negative electrode active material layer 31 is not particularly limited, for example, it can be 0.1 μm or more, 1 μm or more, 10 μm or more, or 30 μm or more, or it can be less than 2 mm, less than 1 mm, less than 500 μm, or less than 100 μm. The negative electrode active material can be any of the materials known as negative electrode active materials for batteries. For example, silicon-based active materials such as Si, Si alloys, and silicon oxide; carbon-based active materials such as graphite and hard carbon; various oxide-based active materials such as lithium titanate; and the aforementioned metallic lithium and lithium alloys can be used. A single negative electrode active material can be used alone, or two or more can be used in combination. The shape of the negative electrode active material can be the general shape of a negative electrode active material used in a battery. For example, the negative electrode active material can be in particle form. These particles can be primary particles or secondary particles formed by the aggregation of multiple primary particles. The average particle size (D50) of the negative electrode active material particles can be, for example, 1 nm or more, 5 nm or more, or 10 nm or more; alternatively, it can be 500 μm or less, 100 μm or less, 50 μm or less, or 30 μm or less. Alternatively, as mentioned above, the negative electrode active material can also be foil-shaped or film-shaped metallic lithium. That is, the negative electrode active material layer 31 can be composed of sheets of negative electrode active material. The electrolyte that can be included in the negative electrode active material layer 31 can be, for example, the aforementioned solid electrolytes, electrolyte solutions, or combinations thereof. The conductive material that may be included in the negative electrode active material layer 31 can be appropriately selected from carbon and other metal materials, as exemplified above as conductive materials that may be included in the positive electrode composite material layer 11. The binder that may be included in the negative electrode active material layer 31 can be appropriately selected from the binders exemplified above as binders that may be included in the positive electrode composite material layer 11. The electrolyte, conductive additive, and binder may each be used individually, or two or more may be used in combination.

[0070] 1.3.2 Negative current collector

[0071] The negative electrode current collector 32 can be any material capable of functioning as a negative electrode current collector in a battery. The negative electrode current collector 32 can be a metal foil or metal mesh, or it can be a carbon sheet. Metal foils, in particular, offer excellent operability. The negative electrode current collector 32 can be composed of two or more metal foils or sheets. Examples of metals constituting the negative electrode current collector 32 include Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, and stainless steel. Specifically, from the viewpoint of ensuring reduction resistance and preventing alloying with lithium, the negative electrode current collector 32 can be a current collector containing at least one metal selected from Cu, Ni, and stainless steel, particularly a current collector containing at least one metal selected from Ni and stainless steel. The negative electrode current collector 32 can have a coating on its surface. For example, the negative electrode current collector 32 can have a protective layer on its surface. In one embodiment, the negative electrode current collector 32 can have a conductive substrate selected from the aforementioned metal foil, metal mesh, or carbon sheet, and a protective layer formed on the surface of the conductive substrate. The protective layer may, for example, contain Mg. It is believed that by having a Mg-containing protective layer on the negative electrode current collector 32, the diffusion of Li on the surface of the negative electrode current collector 32 is promoted, the affinity of metallic lithium for the negative electrode current collector 32 is increased, the voids between the negative electrode current collector 32 and metallic lithium are suppressed, and metallic lithium is deposited more uniformly on the surface of the negative electrode current collector 32. Furthermore, when the negative electrode current collector 32 is composed of two or more metal foils, a layer may be formed between the two or more metal foils. The thickness of the negative electrode current collector 32 is not particularly limited. For example, it may be 0.1 μm or more, or 1 μm or less, or 1 mm or less, or 100 μm or less.

[0072] 1.4 Other components

[0073] In addition to the above-described configuration, the battery 100 may also have a general battery configuration, such as tabs and terminals. The battery 100 may be a battery in which the above-described configurations are housed within an outer casing. The outer casing may be any type of known battery casing. Furthermore, two or more batteries 100 may be arbitrarily electrically connected, or arbitrarily stacked to form a battery pack. In this case, the battery pack can be housed within a known battery casing. Examples of battery 100 shapes include coin-shaped, laminated, cylindrical, and square. The battery 100 may have a constraint member for constraining the above-described configurations along the thickness direction. By applying constraint pressure through the constraint member, the internal resistance of the battery can be easily reduced. There are no particular limitations on the constraint pressure based on the constraint member. The constraint pressure based on the constraint member may be 5 MPa or less, 3 MPa or less, or 1 MPa or less. The battery 100 may be a rechargeable battery. Alternatively, the battery 100 may be a lithium-sulfur battery (LiS battery). Furthermore, the battery 100 may be a completely solid-state battery that substantially does not contain a liquid electrolyte. In addition, battery 100 can be an all-solid-state lithium-sulfur battery.

[0074] 2. Battery manufacturing method

[0075] In addition to using the aforementioned positive electrode composite material, battery 100 can be manufactured by applying known methods. In one embodiment, battery 100 can be manufactured as follows. However, the manufacturing method of battery 100 is not limited to the following methods; for example, the layers can also be formed by dry forming or the like.

[0076] (1) A slurry for the positive electrode layer is obtained by dispersing sulfur-based active materials, etc., constituting the positive electrode composite material layer in a solvent. There are no particular limitations on the solvent used at this time, and various organic solvents can be used. The slurry for the positive electrode layer is applied to the roughened surface (contact surface) of the positive electrode current collector using a doctor blade or the like, and then dried, thereby forming a positive electrode composite material layer on the roughened surface (contact surface) of the positive electrode current collector, and a positive electrode is produced.

[0077] (2) Prepare a lithium metal foil as the negative electrode active material and combine it with a negative electrode current collector to form a negative electrode. Alternatively, disperse the negative electrode active material constituting the negative electrode active material layer in a solvent to obtain a slurry for the negative electrode layer. There are no particular limitations on the solvent used at this time; water or various organic solvents can be used. Apply the slurry for the negative electrode layer to the surface of the negative electrode current collector using a doctor blade or the like, and then let it dry, thereby forming a negative electrode active material layer on the surface of the negative electrode current collector to form a negative electrode.

[0078] (3) The layers are stacked in such a way that the electrolyte layer (solid electrolyte layer or membrane) is sandwiched between the negative electrode and the positive electrode to obtain a laminate having a negative electrode current collector, a negative electrode active material layer, an electrolyte layer, a positive electrode composite material layer and a positive electrode current collector in sequence. Other components such as terminals are installed on the laminate as needed.

[0079] (4) The laminate is housed in a battery casing. In the case of an electrolyte battery, electrolyte is filled into the battery casing, the laminate is immersed in the electrolyte, and the laminate is sealed in the battery casing to make a battery.

[0080] 3. Vehicles

[0081] As described above, the battery of the present invention has excellent cycle characteristics. Such a battery can be suitably used, for example, in at least one vehicle selected from hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs). Specifically, the technology of the present invention is a vehicle having a battery, characterized in that the battery has a positive electrode composite material layer, an electrolyte layer, and a negative electrode, wherein the positive electrode composite material layer comprises a sulfur-based active material, a P-containing sulfide, and carbon, and the carbon has a BET specific surface area of ​​350 m². 2 / g or more, the molar ratio of P to S in the above-mentioned positive electrode composite material layer is greater than 0.06 and less than 0.24. The battery components are as described above.

[0082] [Example]

[0083] As described above, one embodiment of the battery, etc., has been explained; however, the technology of the present invention can be modified in various ways beyond the above-described embodiment without departing from its spirit. Hereinafter, embodiments are shown and the technology of the present invention is described in more detail, but the technology of the present invention is not limited to the following embodiments.

[0084] 1. Fabrication of positive electrode composite materials

[0085] Elemental sulfur (vacuum-dried at 80°C), a sulfur-containing sulfide (P₂S₅), and carbon (vacuum-dried at 120°C), a conductive material, were weighed in a specified mass ratio and mixed using a mortar to obtain a mixture. 1.7 g of this mixture was then added to each ball mill jar. 80g of 4mm zirconia balls were mixed at 400rpm using a planetary ball mill for 36 hours. After mixing using the planetary ball mill, the mixture was dry-graded using a 38μm sieve to obtain the cathode composite material. It should be noted that any of the following can be used as carbon: single-layer carbon nanotubes (single-layer CNTs), multi-layer carbon nanotubes (multi-layer CNTs), or porous carbon. Furthermore, two types of multi-layer CNTs with different specific surface areas were prepared, and any one of them was used.

[0086] 2. Fabrication of pressed battery cells

[0087] Using the positive electrode composite material prepared as described above, follow these steps to produce... The pressed battery cell is 11.28mm thick. The structure of the manufactured pressed battery cell is as follows: Figure 2 As shown.

[0088] (1) Add 100mg of sulfide solid electrolyte to the battery cell and press it with 1 ton.

[0089] (2) 7.6 mg of positive electrode composite material was added to the upper side of the sulfide solid electrolyte layer in the battery cell and pressed with 1 ton.

[0090] (3) Apply a solution to the upper side of the positive electrode composite material layer inside the battery cell. Al foil cut to 11.28mm is pressed with 6 tons.

[0091] (4) Add the following to the lower side of the sulfide solid electrolyte layer in the battery cell in sequence: Li-10 wt% Mg alloy foil (100μm thick) and Ni foil, cut from 11.28mm, are pressed at 1 ton.

[0092] (5) A fixed-size constraint of 2 Nm (equivalent to about 30 MPa) is applied to obtain the pressed battery cell for evaluation.

[0093] 3. Evaluation Methods

[0094] 3.1BET specific surface area

[0095] The BET specific surface area of ​​the carbon used in the cathode composite material was determined. It can be said that the BET specific surface area of ​​this carbon is substantially the same before and after mixing using a planetary ball mill. The results show that the BET specific surface area of ​​monolayer CNTs is 1188 m². 2 / g, the BET specific surface area of ​​multilayer CNT(1) is 275m². 2 / g, the BET specific surface area of ​​multilayer CNT(2) is 387m². 2 / g, the BET specific surface area of ​​porous carbon is 1517m². 2 / g.

[0096] 3.2 molar ratio P / S

[0097] The molar ratio P / S in the cathode composite material layer is determined by the mixing ratio of elemental sulfur and P2S5 during the production of the cathode composite material.

[0098] 3.3 Electrochemical Measurement

[0099] For pressed battery cells manufactured as described above, at a cutoff potential of 3.1V-1.2V vs Li + The range of / Li is set to 1C = 5.84mA / cm. 2 The constant current charge-discharge test shall be carried out at 60°C in accordance with the following procedure.

[0100] Adjustment (1.2V discharge) and cycles 1-3: Current density 0.584 mA / cm² 2 This is equivalent to 0.1C; After this point: current density 1.168 mA / cm² 2 This is equivalent to 0.2C.

[0101] 4. Evaluation Results

[0102] Table 1 below shows the types of carbon contained in the positive electrode composite layer, the BET specific surface area of ​​the carbon contained in the positive electrode composite layer, the mass ratio of elemental sulfur and P2S5 to carbon in the positive electrode composite layer, the molar ratio P / S in the positive electrode composite layer, the discharge capacity C0 when the battery cell is pressed, the discharge capacity C1 in the first charge-discharge cycle, and the discharge capacity C20 in the 20th charge-discharge cycle.

[0103] [Table 1]

[0104] According to the results shown in Table 1, batteries that have a positive electrode composite layer, an electrolyte layer and a negative electrode and satisfy the following (1) to (3) can be said to have excellent cycle characteristics.

[0105] (1) The above positive electrode composite material layer contains sulfur-based active materials, P-containing sulfides and carbon.

[0106] (2) The BET specific surface area of ​​the carbon mentioned above is 350 m². 2 / g or more.

[0107] (3) The molar ratio of P to S in the above positive electrode composite material layer is greater than 0.06 and less than 0.24.

[0108] It should be noted that in the above embodiments, the cathode composite material layer is illustrated as containing sulfur-based active materials, P2S5 as a P-containing sulfide, and carbon as a conductive material, and does not contain any other components. However, the composition of the cathode composite material layer is not limited to this. It is believed that as long as the cathode composite material layer satisfies the above (1) to (3), excellent cycle characteristics can be ensured.

[0109] Symbol Explanation

[0110] 100 batteries

[0111] 10 Positive electrode

[0112] 11 Positive electrode composite material layer

[0113] 12 Positive current collector

[0114] 20 Electrolyte layer

[0115] 30 Negative electrode

[0116] 31 Negative Electrode Active Material Layer

[0117] 32 Negative current collector

Claims

1. A battery comprising a positive electrode composite material layer, an electrolyte layer, and a negative electrode. The positive electrode composite material layer contains sulfur-based active materials, P-containing sulfides, and carbon. The BET specific surface area of the carbon is 350 m 2 / g or more, The molar ratio of P to S in the positive electrode composite material layer is greater than 0.06 and less than 0.

24.

2. The battery of claim 1, wherein, The carbon is carbon nanotubes.

3. The battery of claim 1, wherein, The BET specific surface area of the carbon is 1000 m 2 / g or more.

4. The battery of claim 1, wherein, The electrolyte layer contains a solid electrolyte.

5. The battery according to any one of claims 1 to 4, wherein The negative electrode undergoes lithium metal deposition during charging and lithium metal dissolution during discharging.

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