Battery, negative electrode material, and multilayer body

Abstract

Disclosed is a battery which comprises: a negative electrode that has a negative electrode active material layer; and a solid electrolyte layer that is in contact with the negative electrode active material layer. The negative electrode active material layer contains a negative electrode active material that contains phosphorus, and occludes or releases ions of an alkali metal when the alkali metal is used as a counter electrode and 0.1 V or more is applied thereto. Either or both of the negative electrode active material layer and the solid electrolyte layer contain a halogen-based solid electrolyte. The halogen-based solid electrolyte contains an alkali metal element, a metalloid element or a metal element other than alkali metal elements, and a halogen element.

Description

Battery, negative electrode material and laminate

[0001] This application claims priority to Japanese Patent Application No. 2023-127805, filed on August 4, 2023, the contents of which are incorporated herein by reference.

[0002] In batteries such as lithium-ion batteries, an electrolyte having metal ion conductivity is disposed between a positive electrode active material and a negative electrode active material. Each active material exchanges metal ions through the electrolyte to charge or discharge. Solid electrolytes, which are highly safe and easy to handle, have been investigated as such electrolytes (see, for example, Patent Documents 1 and 2).

[0003] Solid electrolytes have a higher hardness than conventional electrolyte solutions, which can suppress the growth of lithium dendrites that can form in the negative electrode active material. Therefore, batteries using solid electrolytes are expected to improve the durability of the battery.

[0004] Chinese Patent Application No. 112448100 Chinese Patent Application No. 110247111

[0005] On the other hand, in conventional batteries, there is still room for improvement in the peripheral structure of the negative electrode active material in order to improve the performance of lithium secondary batteries.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a battery that ensures good ionic conduction with the negative electrode active material and has high durability. Another aim is to provide a negative electrode material and a laminate that can easily ensure good ionic conduction with the negative electrode active material.

[0007] In order to solve the above problems, one aspect of the present invention includes the following: [1] A battery comprising: a negative electrode having a negative electrode active material layer; and a solid electrolyte layer in contact with the negative electrode active material layer, wherein the negative electrode active material layer contains phosphorus and a negative electrode active material that occludes or releases ions of the alkali metal when a voltage of 0.1 V or more is applied using an alkali metal as a counter electrode, and either or both of the negative electrode active material layer and the solid electrolyte layer contain a halogen-based solid electrolyte, wherein the halogen-based solid electrolyte contains an alkali metal element, a metal element or a metalloid element other than the alkali metal element, and a halogen element. [2] The battery according to [1], wherein both the negative electrode active material layer and the solid electrolyte layer contain the halogen-based solid electrolyte. [3] The battery according to [1] or [2], wherein the negative electrode active material is a phosphorus-carbon composite material containing a phosphorus atom and a carbon atom. [4] The phosphorus atom content in the phosphorus-carbon composite material is 10% by mass or more and 95% by mass or less, the carbon atom content in the phosphorus-carbon composite material is 5% by mass or more and 90% by mass or less, and the weight loss rate WL at a measurement temperature of 620°C obtained by thermogravimetry under the following conditions is ６２０ and the weight loss rate WL at a measurement temperature of 780 ° C. ７８０ Relative to WL ６２０ / WL ７８０ The battery according to [3], wherein is 0.1 or more and 0.9 or less. (Thermogravimetric Measurement) 10 mg of the phosphorus-carbon composite material is precisely weighed out as a sample, and a thermogravimetric measuring device is used to measure the change in weight when heated from 50°C to 780°C at a temperature increase rate of 10°C / min under a nitrogen gas flow. (Weight Loss Rate) The ratio of the weight of the sample at the measurement temperature to the weight of the precisely weighed sample is defined as the weight loss rate (wt%) at the measurement temperature. [5] The weight loss rate WL at a measurement temperature of 300°C determined by the above thermogravimetric measurement ３００ and the weight loss rate WL at a measurement temperature of 600 ° C. ６００ Relative to WL ３００ / WL ６００ [6] The battery according to [4], wherein the XPS spectrum has a peak indicating a bond between a phosphorus atom and a carbon atom. [7] In an XRD profile measured using CuKα radiation, the intensity I at 2θ=20° is ２０, intensity I at 2θ=26.3° ２６．３ , and the intensity at 2θ=40° I ４０ The battery according to [4], wherein |P| / |B|<2 (1) satisfies the following formulas (1) to (3): ２６．３ -I ４０ ...(2) B = (I ２０ -I ４０ )×(26.3−40) / (20−40) …(3) [8] The battery according to [4], which has a core particle containing a phosphorus atom and a carbon coating covering the surface of the core particle. [9] An anode material comprising an anode active material and a halogen-based solid electrolyte, wherein the anode active material contains phosphorus and absorbs or releases ions of the alkali metal when a voltage of 0.1 V or more is applied using an alkali metal as a counter electrode, and the halogen-based solid electrolyte contains an alkali metal element, a metal element or a metalloid element other than the alkali metal element, and a halogen element.

[10] A laminate comprising: a negative electrode having a negative electrode active material layer; and a solid electrolyte layer in contact with the negative electrode active material layer, wherein the solid electrolyte layer contains a halogen-based solid electrolyte, the halogen-based solid electrolyte contains an alkali metal element, a metal element or a metalloid element other than the alkali metal element, and a halogen element, and the negative electrode active material contained in the negative electrode active material layer absorbs or releases ions of the alkali metal when a voltage of 0.1 V or more is applied using an alkali metal as a counter electrode.

[0008] According to the present invention, it is possible to provide a battery that ensures good ionic conduction with the negative electrode active material and has high durability. Also, it is possible to provide a negative electrode material and a laminate that can easily ensure good ionic conduction with the negative electrode active material.

[0009] In this embodiment, whether or not a battery has high durability is evaluated by a charge-discharge test and a charge-discharge cycle test of the battery described in the Examples.

[0010] FIG. 1 is a schematic diagram showing an example of an all-solid-state lithium secondary battery. FIG. 2 is a graph showing the results of thermogravimetric measurements of a PC material and a PC mixture. FIG. 3 is an XPS spectrum of the PC material and the PC mixture. FIG. 4 is a transmission electron microscope (TEM) photograph of the PC material. FIG. 5 is an XRD profile of the PC material and the PC mixture. FIG. 6 is a charge / discharge curve showing the results of a charge / discharge test (measurement condition 1) of Example 1. FIG. 7 is a charge / discharge curve showing the results of a charge / discharge test (measurement condition 2) of Example 1. FIG. 8 is a plot of the charge / discharge capacity and coulombic efficiency for each cycle of Example 1. FIG. 9 is a charge / discharge curve showing the results of a charge / discharge test of Example 2. FIG. 10 is a charge / discharge curve showing the results of a charge / discharge test of Example 3. FIG. 11 is a charge / discharge curve showing the results of a charge / discharge test of Example 4. FIG. 12 is a charge / discharge curve showing the results of a charge / discharge test of Example 5. FIG. 13 is a graph showing the results of the charge and discharge operation in Comparative Example 1.

[0011] The battery, negative electrode material, and laminate according to this embodiment will be described below with reference to Figures 1 to 5. Note that in all of the following figures, the dimensions and proportions of the components have been appropriately changed to make the drawings easier to understand.

[0012] <Battery and Laminate> The battery of this embodiment has a positive electrode, a negative electrode having a negative electrode active material layer, and a solid electrolyte layer disposed between the positive electrode and the negative electrode. The solid electrolyte layer is in contact with the negative electrode active material layer. Each of these components will be described below.

[0013] Fig. 1 is a schematic diagram showing an all-solid-state lithium secondary battery, which is an example of a battery. The all-solid-state lithium secondary battery 1000 shown in Fig. 1 includes a laminate 100 having a positive electrode 110, a negative electrode 120, and a solid electrolyte layer 130, and an exterior body 200 that houses the laminate 100. The all-solid-state lithium secondary battery 1000 may also have a bipolar structure in which a positive electrode active material and a negative electrode active material are disposed on both sides of a current collector. A specific example of a bipolar structure is the structure described in JP-A-2004-95400.

[0014] The positive electrode 110 has a positive electrode active material layer 111 and a positive electrode current collector 112. The positive electrode active material layer 111 contains a positive electrode active material and a solid electrolyte. The positive electrode active material layer 111 may also contain a conductive material and a binder. The solid electrolyte that the positive electrode active material may contain is not particularly limited, and any known solid electrolyte can be used. From the viewpoint of ensuring good ion conduction, the solid electrolyte is preferably the same as the solid electrolyte contained in the negative electrode active material layer and the solid electrolyte layer, and specifically, a halogen-based solid electrolyte is preferred.

[0015] The negative electrode 120 has a negative electrode active material layer 121 and a negative electrode current collector 122. The negative electrode active material layer 121 contains a negative electrode active material. The negative electrode active material layer 121 also contains a halogen-based solid electrolyte, and may also contain a solid electrolyte other than the halogen-based solid electrolyte or a conductive material.

[0016] The laminate 100 may have an external terminal 113 connected to the positive electrode current collector 112 and an external terminal 123 connected to the negative electrode current collector 122. In addition, the all-solid-state lithium secondary battery 1000 may have a separator between the positive electrode 110 and the negative electrode 120.

[0017] The all-solid-state lithium secondary battery 1000 further includes an insulator (not shown) that insulates the laminate 100 from the exterior body 200 , and a sealing body (not shown) that seals the opening 200 a of the exterior body 200 .

[0018] The exterior body 200 may be a container molded from a highly corrosion-resistant metal material such as aluminum, stainless steel, or nickel-plated steel. Alternatively, the exterior body 200 may be a bag-shaped container made of a laminate film having corrosion resistance on at least one surface.

[0019] The shape of the all-solid-state lithium secondary battery 1000 may be, for example, a coin type, a button type, a paper type (or a sheet type), a cylindrical type, a square type, or a laminate type (pouch type).

[0020] Although the all-solid-state lithium secondary battery 1000 is illustrated as having one laminate 100 as an example, the present embodiment is not limited to this. The all-solid-state lithium secondary battery 1000 may have a configuration in which the laminate 100 is used as a unit cell, and a plurality of unit cells (laminated bodies 100) are sealed inside an exterior body 200.

[0021] For the all-solid-state lithium secondary battery, for example, the configuration, materials and manufacturing method described in paragraphs

[0141] to

[0181] of WO2022 / 113904A1 can be used.

[0022] <<Active Material>> Examples of the positive electrode active material include lithium-containing composite metal oxides containing lithium (Li) and at least one transition metal selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, and Al. Examples of such lithium composite metal oxides include LiCoO ２ , LiNiO ２ , LiMn ２ 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 Examples include:

[0023] <Negative Electrode> The negative electrode of a lithium ion battery is not particularly limited, and may include a negative electrode active material containing phosphorus that can absorb or release lithium ions when a voltage of 0.1 V or more is applied using lithium as a counter electrode, and may also include a conductive additive, a binder, etc. as necessary. Examples of the negative electrode include an alloy of phosphorus and a metal element, a composite containing phosphorus, a carbon material containing phosphorus, and a substance in which lithium ions are inserted between layers of the carbon material. Examples of the metal element include elements such as Li, Si, Sn, Si—Mn, Si—Co, Si—Ni, In, and Au.

[0024] [Phosphorus-Carbon Composite Material] Furthermore, the negative electrode active material is preferably a phosphorus-carbon composite material containing phosphorus atoms and carbon atoms. In the following description, the "phosphorus-carbon composite material" may be simply abbreviated as "P-C material." One embodiment of the P-C material is a phosphorus-carbon material containing phosphorus atoms and carbon elements. One embodiment of the P-C material is a composite material containing phosphorus atoms, carbon elements, and a resin component.

[0025] When the PC material is a composite material, the resin component is preferably a material used as a binder resin in secondary batteries, specifically a thermoplastic resin binder or a water-based binder.

[0026] Examples of the thermoplastic binder include fluororesins such as polyvinylidene fluoride, polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymers, hexafluoropropylene-vinylidene fluoride copolymers, and tetrafluoroethylene-perfluorovinyl ether copolymers; polyolefin resins such as polyethylene and polypropylene; and amide resins such as polyimide and polyamideimide. The thermoplastic binder is preferably a fluororesin, and more preferably polyvinylidene fluoride.

[0027] An example of the water-based binder is styrene butadiene rubber (SBR).

[0028] When the PC material is a composite material, the content of the resin component is preferably 0.5% by mass or more and 12% by mass or less, more preferably 2% by mass or more and 10% by mass or less, and even more preferably 3% by mass or more and 7% by mass or less, relative to the total amount of the composite material.

[0029] The PC material has a phosphorus atom content of 10% by mass or more and 95% by mass or less. The carbon atom content of the PC material is 5% by mass or more and 90% by mass or less. When the PC material is composed of phosphorus atoms and carbon atoms, the sum of the carbon atom content and the phosphorus atom content in the PC material is 100% by mass. Even when the PC material is composed of carbon atoms and phosphorus atoms, impurities that are inevitably mixed in from the raw materials and manufacturing process of the PC material are permitted.

[0030] The PC material is composed of 60 mass% or more of phosphorus atoms and carbon atoms, and may further contain elements other than phosphorus atoms and carbon atoms. Examples of elements other than phosphorus atoms and carbon atoms contained in the PC material include lithium, silicon, germanium, tin, aluminum, zinc, magnesium, transition metals, nitrogen, oxygen, fluorine, silicon, titanium, niobium, sulfur, and chlorine. These can be obtained from metal oxides, composite metal oxides, metal fluorides, metal sulfides, metal chlorides, silicon oxides, silicates, titanates, and aluminates.

[0031] The content of phosphorus atoms, the content of carbon atoms, and the content of other atoms that may be contained in the PC material can be determined by known ICP analysis.

[0032] In the PC material, the content of the phosphorus atoms is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 50% by mass or more. A higher phosphorus content increases the initial charge / discharge capacity of the PC material. Furthermore, in the PC material, the content of the phosphorus atoms is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less. This is because if the content of phosphorus atoms is too high, the cycle characteristics of the PC material will deteriorate. The upper and lower limits of the content of phosphorus atoms can be combined arbitrarily.

[0033] In the PC material, the carbon atom content is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more. A higher carbon atom content improves the cycle characteristics of the PC material. Furthermore, in the PC material, the carbon atom content is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 50% by mass or less. This is because if the carbon atom content is too high, the initial charge / discharge capacity of the PC material decreases. The upper and lower limits of the carbon atom content can be combined arbitrarily.

[0034] As will be described in detail later, the PC material can be produced by ball milling phosphorus and a carbon material, or by ball milling a phosphorus material, a carbon raw material, and a binder resin. The inventors conducted detailed analysis and investigation of the obtained PC material and confirmed that the PC material is not a simple mixture of the raw materials, phosphorus and a carbon material, but rather that the phosphorus atoms and carbon atoms in the PC material are chemically bonded (covalently bonded), resulting in a novel material with physical properties different from those of the raw materials, phosphorus and carbon materials. Even when the phosphorus material, the carbon raw material, and the binder resin are ball milled, a negative electrode active material in which the phosphorus atoms and carbon atoms are chemically bonded (covalently bonded) is produced.

[0035] The physical properties of PC materials will be described in detail below, comparing them with a mixture of phosphorus and a carbon material (hereinafter sometimes referred to as a "PC mixture").

[0036] The following explanation compares an example of a PC material with an example of a mixture obtained by mixing the same raw materials as the PC material in a mortar. In the example shown below, the raw materials for the PC material and the PC mixture both contain black phosphorus and a carbon material in a mass ratio of 6:4. In both the PC material and the PC mixture, CSCNT (cup-stacked carbon nanotubes) are used as the carbon material.

[0037] [Heat behavior] The PC material has a weight loss rate WL at a measurement temperature of 620°C, which is determined by thermogravimetry under the following conditions: ６２０ and the weight loss rate WL at a measurement temperature of 780 ° C. ７８０ Relative to WL ６２０ / WL ７８０ is 0.1 or more and 0.9 or less. (Thermogravimetric Measurement) 10 mg of the phosphorus-carbon composite material is precisely weighed out as a sample, and a thermogravimetric measuring device is used to measure the change in weight when heated from 50°C to 780°C at a temperature increase rate of 10°C / min in a nitrogen stream. (Weight Loss Rate) The ratio of the weight of the sample at the measurement temperature to the weight of the precisely weighed sample is defined as the weight loss rate (wt %) at the measurement temperature.

[0038] Figure 2 is a graph showing the results of the thermogravimetric measurements of the PC material and the PC mixture. In Figure 2, the horizontal axis represents the heating temperature (°C) and the vertical axis represents the weight loss rate (wt%) relative to the sample weight. In Figure 2, the symbol A represents the behavior of the PC material, and the symbol X represents the behavior of the PC mixture.

[0039] As shown in FIG. 2, for the PC mixture, the weight loss rate WL at the measurement temperature of 620°C was ６２０ (Indicated by symbol X1 in FIG. 2) and the weight loss rate WL at a measurement temperature of 780°C ７８０ (indicated by symbol X2 in FIG. 2) ６２０ / WL ７８０ The PC mixture exhibited a steep weight loss at measurement temperatures of around 350°C to 450°C, and at 620°C, the sample had lost approximately 60% of its initial weight.

[0040] This weight loss is thought to correspond to the weight of the raw material black phosphorus. In the case of the PC mixture, it is thought that the black phosphorus contained in the PC mixture was lost due to heating. It is known that black phosphorus changes into its allotrope, red phosphorus, when heated to 125°C. It is also known that red phosphorus sublimes at 416°C under normal pressure.

[0041] On the other hand, the weight loss rate of the PC material at a measurement temperature of 620°C is WL ６２０ (Indicated by symbol A1 in FIG. 2) and the weight loss rate WL at a measurement temperature of 780°C ７８０ (indicated by symbol A2 in FIG. 2) ６２０ / WL ７８０ is included in the range of 0.1 to 0.9.

[0042] In addition, the PC material has a weight loss rate WL at a measurement temperature of 300°C obtained by the above thermogravimetry. ３００ (Indicated by symbol A3 in FIG. 2) and the weight loss rate WL at a measurement temperature of 600°C ６００ (shown as symbol A4 in FIG. 2) ３００ / WL ６００ is preferably in the range of −0.1 to 0.1.

[0043] That is, unlike the PC mixture, the PC material shows almost no weight loss up to a measurement temperature of 300°C and is thermally stable at the measurement temperature of 300°C.

[0044] W.L. ６２０ / WL ７８０ is preferably 0.1 or more, more preferably 0.3 or more, and even more preferably 0.5 or more. ６２０ / WL ７８０ is preferably 0.9 or less, more preferably 0.8 or less. ６２０ / WL ７８０ The upper and lower limits can be combined arbitrarily.

[0045] W.L. ３００ / WL ６００ is preferably −0.1 or more, more preferably −0.08 or more. ３００ / WL ６００ is preferably 0.1 or less, more preferably 0.08 or less. ３００ / WL ６００ The upper and lower limits can be combined arbitrarily.

[0046] From the results shown in Figure 2, it is believed that the black phosphorus used as a raw material in the PC material changes, resulting in a substance that behaves differently from black phosphorus in response to heat.

[0047] [Presence or absence of P-C bond] A P-C material has a peak indicative of a bond between a phosphorus atom and a carbon atom in an XPS spectrum. It is known that the "peak indicative of a bond between a phosphorus atom and a carbon atom" appears in the range of 132 to 136 eV in an XPS spectrum. In the following description, the bond between a phosphorus atom and a carbon atom may be simply referred to as a "P-C bond."

[0048] Figure 3 shows XPS spectra of the PC material and the PC mixture. In Figure 3, the horizontal axis represents binding energy (eV) and the vertical axis represents the number of detected photoelectrons (cps (counts per second)). In Figure 3, symbol A represents the PC material, and symbol X represents the PC mixture.

[0049] (XPS Spectrum Measurement Conditions) XPS spectra are measured under the following measurement conditions: Measuring instrument: XPS device, ESCA-3400 (manufactured by Shimadzu Corporation) Radiation source: Mg Kα radiation (20 mA, 10 kV) If a peak is detected in the range of 132 to 136 eV, it is determined that a P—C bond is present.

[0050] As shown in FIG. 3, no peak indicating a P—C bond was detected in the range of 132 to 136 eV in the P—C mixture, but a peak indicating a P—C bond (denoted by the symbol α) was detected in the P—C material.

[0051] From the results shown in FIG. 3, it is believed that the PC material is a substance having a chemical bond between the phosphorus atom and the carbon atom.

[0052] [Appearance] The PC material has a core particle containing phosphorus atoms and a carbon coating covering the surface of the core particle.

[0053] Fig. 4 is a transmission electron microscope (TEM) photograph of the PC material. As shown in Fig. 4, a particle 50 of the PC material has a core-shell structure in which the surface of a core particle 51 containing phosphorus atoms is covered with a carbon coating 52.

[0054] The presence of phosphorus atoms and carbon atoms in the PC material can be confirmed by using EDX (Energy Dispersive X-ray Spectroscopy).

[0055] Furthermore, when the PC material is composed only of phosphorus atoms and carbon atoms, the heavier phosphorus atoms appear darker in the TEM photograph, and therefore, based on the TEM photograph, it can be easily determined that the PC material has a core-shell structure in which core particles 51 contain phosphorus atoms and are covered with carbon coatings 52 containing carbon atoms.

[0056] (TEM photographing conditions) TEM photographs are taken under the following photographing conditions: TEM device: Transmission electron microscope H-9000NAR (manufactured by Hitachi, Ltd.) Field of view: maximum 500 nm x 500 nm At least a part of the particles of the PC material is included in the field of view when photographing.

[0057] According to the above-described TEM photographing conditions, the core-shell structure can be similarly confirmed whether the PC material is made of a phosphorus-carbon material containing phosphorus atoms and carbon elements or a composite material containing a PC material and a resin component.

[0058] In addition to satisfying the requirements for thermal behavior described above, the PC material preferably has the core-shell structure described above.

[0059] [Crystalline state] Figure 5 shows XRD profiles of the PC material and the PC mixture. In Figure 5, the horizontal axis represents the diffraction angle (2θ, °) and the vertical axis represents the diffracted X-ray intensity (a.u.). In Figure 5, the symbol A represents the PC material and the symbol X represents the PC mixture.

[0060] (XRD Profile Measurement Conditions) The XRD profile is measured under the following measurement conditions: Measurement equipment: horizontal sample multipurpose X-ray diffractometer Ultima IV (manufactured by Rigaku Corporation) Radiation source: Cu Kα radiation Measurement range (2θ): 10° to 90° Scan speed: 4° / min Sampling: 0.02° Voltage: 40 kV, current: 40 mA

[0061] As shown in Figure 5, in the PC mixture, the carbon material and black phosphorus each have a certain degree of crystallinity and exhibit diffraction peaks. In contrast, in the PC material, the diffraction peaks seen in the PC mixture were not observed, and only noise was confirmed throughout the measurement range. In other words, from the results shown in Figure 5, it is believed that in the PC material, the crystallinity of the carbon material used as a raw material has been lost and it has become amorphous, or the carbon material has become so fine that the crystalline state cannot be confirmed.

[0062] Here, when the XRD profile of the PC material is measured under the above conditions, the intensity I at 2θ=20° in the XRD profile measured under the above conditions is２０ , intensity I at 2θ=26.3° ２６．３ , and the intensity at 2θ=40° I ４０ satisfies the following relational expressions (1) to (3): |P| / |B|<2 (1) P=I ２６．３ -I ４０ ...(2) B = (I ２０ -I ４０ ) × (26.3 - 40) / (20 - 40) ... (3)

[0063] When the XRD profile of a raw carbon material is measured, a peak of the carbon material appears at 2θ = 26.3°, which corresponds to the graphite (002) peak. On the other hand, the XRD profile of a normal carbon material does not have peaks at 2θ = 20° or 2θ = 40°. Therefore, in the above formula (1), 2θ = 40°, where no peak of the carbon material exists, is set as the reference point, and the state of the carbon material can be determined by comparing the intensity of the reference point in the XRD profile with the intensity at the position (2θ = 26.3°) where the peak of the raw carbon material exists.

[0064] "P" expressed in the above formula (2) is the intensity I of the reference point ４０ and the intensity I at the position where the peak of the carbon material exists. ２６．３ and indicates the difference of the peak from the reference point.

[0065] "B" in the above formula (3) indicates the baseline intensity at 2θ=26.3°, estimated from two positions (2θ=20° and 2θ=40°) where there are no peaks.

[0066] The ratio of the baseline intensity from the reference point to the peak intensity can be calculated from the ratio of the absolute values ​​of P and B (|P| / |B|) expressed by the above formula (1). When |P| / |B| is 2 or more, it indicates the presence of a peak of the carbon material.

[0067] On the other hand, when |P| / |B| is less than 2 and satisfies formula (1), the peak of the carbon material is reduced, and it can be determined that the crystallinity of the carbon material has decreased and the carbon material is amorphous or has become so fine that the crystalline state cannot be confirmed. Therefore, it is preferable that the P-C material satisfies the above-mentioned requirements for [thermal behavior] as well as the above-mentioned relational expressions (1) to (3).

[0068] As described above, the PC material is a novel substance that differs from the mixture of the raw material phosphorus (black phosphorus in Figures 2 to 5) and a carbon material in its thermal behavior, bonding state, appearance, and crystalline state.

[0069] <<Method 1 for Producing Phosphorus-Carbon Composite Material>> As described above, the PC material can be produced by a production method including a step of compounding a carbon material and phosphorus by a mixing and grinding process accompanied by compression.

[0070] In the above-mentioned production method, the carbon material as a raw material may be amorphous carbon, graphite, porous carbon, mesocarbon microbeads (MCMB), fullerene, carbon nanotube, graphene, graphene oxide, carbon nitrite (C ３ N ４ ), and laminated carbon nanofibers (Carbon nanofiber platelets). All of these carbon materials have a graphite structure.

[0071] Examples of amorphous carbon include carbon black (CB), acetylene black (AB), ketjen black, hard carbon, and soft carbon.

[0072] As fullerenes, C ６０ , C ７２ , C ８４ The following can be mentioned:

[0073] Examples of carbon nanotubes include single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), cup-stacked carbon nanotubes (CSCNTs), and vapor-grown carbon fibers (VGCFs).These have a structure extending in one axial direction (one-dimensional structure).

[0074] Graphene, graphene oxide, carbon nitrite (C ３ N ４ ), laminated carbon nanofibers (carbon nanofiber platelets) have a structure that extends in the plane direction (two-dimensional structure).

[0075] In carbon materials, the edges (edge ​​sites) of the graphite structure are more active than non-edge sites. Therefore, it is assumed that most of the P-C bonds are formed at the edge sites of the carbon material. Therefore, from the viewpoint of facilitating the formation of P-C bonds, it is preferable to use a carbon material that has many edge sites.

[0076] Carbon materials with many edge sites include CSCNT, graphite, mesocarbon microbeads (MCMB), graphene, graphene oxide, and carbon nitrite (C ３ N ４ Among them, CSCNT is preferred as the carbon material.

[0077] In the above-mentioned production method, any of the known phosphorus allotropes can be used as the raw material phosphorus. Among the phosphorus allotropes, black phosphorus is preferred as it is the most chemically stable and a good conductor of electricity.

[0078] In the above manufacturing method, the "mixing and grinding process with compression" refers to a process in which a compressive force is applied to multiple types of powder raw materials, thereby mixing and grinding the raw materials. By subjecting the carbon material and phosphorus to the mixing and grinding process with compression, a strong impact force is applied to the carbon material and phosphorus, which is thought to cause a chemical change that cannot be achieved with a normal mixture while mixing and grinding the raw material powders. As a result, it is thought that a P-C bond that is not present in the raw materials is formed as a product, and a P-C material that does not exhibit the crystalline state seen in the raw materials is obtained.

[0079] The "mixing and grinding treatment accompanied by compression" may be carried out until the peaks derived from the raw materials disappear in the XRD profile of the mixed material, or until the formation of P-C bonds can be confirmed in the XPS spectrum of the mixed material.

[0080] Examples of processing devices (pulverizers) capable of performing mixing and pulverization accompanied by compression include roller mills, jet mills, hammer mills, pin mills, disk mills, rod mills, ball mills, vibration mills, attritors, and bead mills. In the production of PC materials, it is preferable to use an agitation type pulverizer equipped with a grinding vessel and a rotor, particularly because mixing and pulverization can be performed simultaneously. Examples of agitation type pulverizers include pin mills, disk mills, rod mills, ball mills, vibration mills, attritors, and bead mills.

[0081] Furthermore, as the processing device, a media-agitation type mill is preferred because it can mix and pulverize the raw material powder while simultaneously applying a strong impact force to the carbon material and phosphorus. Examples of media-agitation type mills include a ball mill, a vibration mill, an attritor, and a bead mill. Among these, a ball mill is particularly preferred from the viewpoint of easily controlling the property conditions.

[0082] It is believed that the ball mill mixing first causes atomization of phosphorus and decomposition of the carbon material, followed by the formation of P—C bonds. During this ball mill mixing process, phosphorus becomes the core particles described above.

[0083] It is believed that the carbon film is then formed around the core particles containing phosphorus atoms, resulting in a composite, thereby obtaining a PC material.

[0084] During ball mill mixing, the production conditions can be controlled by adjusting the rotation speed of the ball mill, the amount of media (balls) relative to the raw materials (ball powder ratio), and the mixing time. That is, by adjusting the conditions such as increasing the rotation speed of the ball mill, increasing the amount of media relative to the raw materials, and lengthening the mixing time, the mixing of phosphorus and carbon material is promoted, making it easier to obtain a P-C material. By controlling the above production conditions, the formation of P-C bonds is promoted, and WL ６２０ / WL ７８０ It is easy to produce a PC material that satisfies the following:

[0085] Balls are grinding media for grinding metal materials. The diameter of the balls is the average particle size of the balls. The balls flow at high speed within the grinding container as the grinding container of the grinder rotates, colliding with the powder raw material containing the carbon material and phosphorus, thereby grinding the raw material into particles with a smaller average particle size. In the grinding process, it is preferable that the grinding container and beads are not excessively worn. Therefore, the shape of the balls is preferably spherical or ellipsoidal.

[0086] The diameter of the balls is preferably larger than the average particle size of the PC material after pulverization. By using such balls, a large amount of pulverization energy can be applied to the metal material, allowing metal particles to be obtained efficiently in a short time. On the other hand, if the diameter of the balls is too large, re-agglomeration of the PC material is promoted, resulting in a PC material with a wide particle size distribution.

[0087] The diameter of the balls is preferably 0.1 to 10 mm, more preferably 1 to 10 mm. When the diameter of the balls is within this range, the formation of P—C bonds is promoted and re-agglomeration can be suppressed. The diameter of the balls placed in the grinding container may be uniform or may vary.

[0088] Examples of materials for the balls include glass, agate, alumina, zirconia, stainless steel, chrome steel, tungsten carbide, silicon carbide, and silicon nitride. Among these, zirconia is preferred because it has a relatively high hardness and is therefore resistant to wear, and its relatively high specific gravity allows for the generation of large pulverization energy. By using these balls, the raw powder of the PC material can be pulverized efficiently.

[0089] The weight ratio of the balls to the raw powder of the PC material is called the ball powder ratio. By increasing the ball powder ratio, a strong impact force can be applied to the raw powder of the PC material with high frequency, which further promotes the formation of PC bonds. If the ball powder ratio is too high, the production amount of the PC material per unit operation decreases. Therefore, the ball powder ratio is preferably 0.5 to 500, more preferably 1 to 200, and even more preferably 10 to 200.

[0090] After the ball mill mixing is completed, the balls are separated from the PC material using a filter or the like.

[0091] The fact that the above-described PC material has been obtained by ball mill mixing can be confirmed by measuring the XRD profile of the mixed material and checking that the peaks derived from the raw materials disappear, as shown in Figure 5. The duration of ball mill mixing can be determined by conducting a preliminary experiment to determine the correspondence between the mixing time and the time required for the peaks derived from the raw materials to disappear. In other words, ball mill mixing should be carried out until the peaks derived from the raw materials disappear in the XRD profile of the mixed material.

[0092] Alternatively, the formation of P-C bonds can be confirmed by measuring the XPS spectrum of the mixed material, as shown in Figure 3. In this case, the duration of ball mill mixing can be determined by conducting a preliminary experiment to determine the relationship between the mixing time and the time required for the formation of P-C bonds. In other words, ball mill mixing should be carried out until the formation of P-C bonds can be confirmed in the XPS spectrum of the mixed material.

[0093] During ball mill mixing, strong localized impacts (pressure) are applied to the carbon material and phosphorus due to collisions between media and between the media and the ball mill container. Although the details are unknown, it is thought that the application of such impacts causes chemical changes that cannot be achieved with normal mixtures, forming P-C bonds that are not present in the raw materials, resulting in a P-C material that does not exhibit the crystalline state seen in the raw materials.

[0094] Therefore, according to the manufacturing method of this embodiment, the carbon material and phosphorus are mixed and crushed while being compressed, so that the above-mentioned PC material can be easily manufactured.

[0095] Furthermore, according to the manufacturing method of this embodiment, the above-mentioned PC material can be easily manufactured by the simple method of mixing a carbon material and phosphorus in a ball mill.

[0096] <<Production Method 2 for Phosphorus-Carbon Composite Material>> When the PC material is a composite material containing a resin component, the PC material can be produced by a production method including a step of mixing a PC material obtained by a method similar to Production Method 1 for Phosphorus-Carbon Composite Material with a composite material to obtain a mixed powder, a step of mixing the obtained mixed powder with a solvent, and a subsequent drying step.

[0097] [Step of Obtaining Mixed Powder] The obtained PC material and a resin component are mixed to obtain a mixed powder. The step of mixing the PC material and the resin component is preferably carried out using a mixer such as a Henschel mixer, a planetary mixer, a microspeed mixer, or a Loedige mixer, or by a method similar to the mixing and grinding process accompanied by compression described above.

[0098] Examples of the resin component include fluororesins such as polyvinylidene fluoride, polytetrafluoroethylene, ethylene tetrafluoride-propylene hexafluoride-vinylidene fluoride copolymers, propylene hexafluoride-vinylidene fluoride copolymers, and ethylene tetrafluoride-perfluorovinyl ether copolymers; and polyolefin resins such as polyethylene and polypropylene.

[0099] The resin component is preferably a fluorine-based resin, more preferably polyvinylidene fluoride.

[0100] The mixing ratio of the resin component is preferably adjusted in consideration of the battery characteristics, with the content ratio of other components being in the range of 1% by mass or more and 15% by mass or less, 2% by mass or more and 12% by mass or less, or 2.5% by mass or more and 8% by mass or less, relative to the total amount of other components other than phosphorus atoms and carbon atoms.

[0101] [Step of Mixing the Obtained Mixed Powder with a Solvent] The obtained mixed powder is mixed with a solvent. The solvent is preferably an organic solvent, and examples of the organic solvent include amine solvents such as N,N-dimethylaminopropylamine and diethylenetriamine, ether solvents such as tetrahydrofuran, ketone solvents such as methyl ethyl ketone, ester solvents such as methyl acetate, and amide solvents such as dimethylacetamide and N-methyl-2-pyrrolidone (hereinafter sometimes referred to as NMP).

[0102] The mixing ratio of the mixed powder to the solvent can be adjusted appropriately within the range of 1:9 to 9:1. A higher solvent ratio allows for more uniform coating, but a larger amount of solvent increases the time required for drying, so a range of 2:8 to 6:4 is preferred.

[0103] [Drying Step] After mixing with the solvent, the resin component is easily fixed by drying. The drying conditions are a drying temperature of 40°C to 280°C and a drying time of 1 minute to 24 hours.

[0104] <<Production Method 3 of Phosphorus-Carbon Composite Material>> The P-C material can be produced by a production method including a step of producing a mixed powder containing a phosphorus material, a carbon material, and a resin component, a step of mixing the obtained mixed powder with a solvent, and a subsequent drying step.

[0105] The phosphorus material, the carbon material, and the resin component are mixed by the method described in the above-mentioned mixing and grinding treatment accompanied by compression to obtain a mixed powder.

[0106] The mixing ratio of the resin component is preferably adjusted in consideration of the battery characteristics, with the content ratio of other components being in the range of 1% by mass or more and 15% by mass or less, 2% by mass or more and 12% by mass or less, or 2.5% by mass or more and 8% by mass or less, relative to the total amount of other components other than phosphorus atoms and carbon atoms.

[0107] [Step of Mixing the Mixed Powder with the Solvent] This is carried out in the same manner as in the method for producing the phosphorus-carbon composite material 2 described above.

[0108] [Drying Step] This is carried out in the same manner as in the method for producing the phosphorus-carbon composite material 2 described above.

[0109] <<Method 4 for Producing a Phosphorus-Carbon Composite Material>> In the method for producing a phosphorus-carbon composite material, an aqueous binder resin can be used as the resin component. The aqueous binder resin is an aqueous dispersion of a binder resin, such as styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), or acrylic resin.

[0110] When using an aqueous binder, it is preferable to produce a PC material by the method described in the above-mentioned "Production Method 1 of Phosphorus-Carbon Composite Material," and then coat the PC material with the aqueous binder. In this case, a high concentration of the aqueous binder resin dispersion is preferable because it shortens the drying time, but it is also preferable to adjust the concentration of the aqueous binder resin dispersion to a viscosity that allows it to be easily mixed with the admixture.

[0111] The mixing ratio of the mixed powder to the aqueous binder resin can be adjusted appropriately within the range of 1:99 to 90:10. The higher the solvent ratio, the more uniform the coating can be. From the viewpoint of shortening the drying time, the mixing ratio of the mixed powder to the aqueous binder resin is preferably within the range of 2:8 to 6:4.

[0112] [Drying Step] After mixing with the solvent, the PC negative electrode material is obtained by drying. The drying conditions are, for example, a drying temperature of 40° C. to 280° C. and a drying time of 1 minute to 24 hours.

[0113] By mixing with a solvent and then drying, the binder resin becomes more easily fixed.

[0114] <Halogen-Based Solid Electrolyte> In the battery of the present embodiment, either or both of the negative electrode active material layer and the solid electrolyte layer contain a halogen-based solid electrolyte. In the battery of the present embodiment, it is preferable that both the negative electrode active material layer and the solid electrolyte layer contain a halogen-based solid electrolyte.

[0115] Solid electrolytes have a higher hardness than conventional electrolyte solutions, which can suppress the growth of lithium dendrites that can form in the negative electrode active material. Therefore, batteries using solid electrolytes are expected to improve the durability of the battery.

[0116] The halogen-based solid electrolyte contains an alkali metal element, a metal element or a metalloid element other than the alkali metal element, and a halogen element. Because the halogen element has a large ionic radius per valence, a solid electrolyte containing a halogen element allows lithium ions to flow easily and tends to have high ionic conductivity. As a result, the use of a halogen-based solid electrolyte makes it easier to ensure good ionic conductivity with the negative electrode active material, and thus makes it easier to obtain a battery with high durability.

[0117] When the negative electrode active material layer contains a halogen-based solid electrolyte, the negative electrode active material and the halogen-based solid electrolyte come into contact with each other inside the negative electrode active material layer, making it easier to ensure an ion-conductive state. Also, when the solid electrolyte layer contains a halogen-based solid electrolyte, the negative electrode active material and the halogen-based solid electrolyte come into contact with each other at the interface between the negative electrode active material layer and the solid electrolyte layer, making it easier to ensure an ion-conductive state. Furthermore, when both the negative electrode active material layer and the solid electrolyte layer contain a halogen-based solid electrolyte, the above-mentioned effects are simultaneously exhibited.

[0118] In a battery having a halogen-based solid electrolyte as the solid electrolyte, a good ionic conduction state is ensured at the interface with the negative electrode active material, and the battery is likely to exhibit higher durability than batteries using conventionally known electrolytic solutions.

[0119] The alkali metal element contained in the halogen-based solid electrolyte may be any of Li, Na, K, Rb, and Cs, but may contain at least one of Li, Na, and K, may contain at least one of Li and Na, or may contain Li.

[0120] The proportion of one type of alkali metal element among the alkali metal elements contained in the halogen-based solid electrolyte may be 80 mol % or more, 90 mol % or more, or 95 mol % or more. The one type of alkali metal element may be at least one of Li, Na, and K, at least one of Li and Na, or Li.

[0121] The content of the alkali metal element in the halogen-based solid electrolyte 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 halogen-based solid electrolyte.

[0122] Examples of the metal elements or metalloid elements other than alkali metal elements include divalent to pentavalent elements, and may include one or more elements selected from the group consisting of trivalent elements and tetravalent elements. The halogen-based solid electrolyte may include one or more metal elements or metalloid elements other than alkali metal elements. Hereinafter, "metal elements or metalloid elements other than alkali metal elements" may be referred to as "element group 1."

[0123] Among element group 1, 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. 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. Tetravalent elements include Zr, Ti, Hf, and Sn, and may be Zr. Pentavalent metal elements include Nb and Ta.

[0124] Element group 1 may include at least one of In and Zr. In this case, the content of element group 1 in the halogen-based solid electrolyte 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 halogen-based solid electrolyte.

[0125] In the halogen-based solid electrolyte, the total amount of Zr and In may be greater than the total amount of alkali metal elements, and metal elements or metalloid elements other than Zr and In. The "total amount of substance" here is, in other words, the total amount of substance of element group 1 other than alkali metal elements, Zr, and In. Note that, when the halogen-based solid electrolyte contains only one of Zr and In, this total amount of substance is the content of the contained element. The total amount of substance of Zr and In in the halogen-based solid electrolyte may be 60 mol % or more, 70 mol % or more, 80 mol % or more, or 90 mol % or more of the total amount of substance of metal elements or metalloid elements other than alkali metal elements.

[0126] In a halogen-based solid electrolyte, when element group 1 includes Y, the content of Y in terms of the amount of substance may be less than the total amount of substance of Zr and In. Note that, when the halogen-based solid electrolyte includes only one of Zr and In, this total amount of substance is the content of the included element. The content of Y in the halogen-based 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 amount of substance of element group 1. The halogen-based solid electrolyte may be substantially free of Y.

[0127] Element group 1 preferably includes a base element and a dopant element X1. The base element is one element of element group 1, and may be a trivalent or tetravalent element, such as In or Zr. The content of the base element relative to the total amount of element group 1 is, for example, 70 mol % or more, 75 mol % or more, or 80 mol % or more.

[0128] The dopant element X1 is an element different from the base element. When the base 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 at least one element selected from the group consisting of Zr, Sn, Nb, and Ta. When the base 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.

[0129] The halogen element contained in the halogen-based solid electrolyte may be any one of F, Cl, Br, and I, or may contain at least one of Cl, Br, and I, or may contain at least one of Cl and Br, or may contain Cl. From the viewpoint of improving the ion-conductivity of the material, the halogen-based solid electrolyte may contain only one halogen element, or may contain two or more halogen elements.

[0130] The content of the halogen element in the halogen-based solid electrolyte is preferably 40 to 70 mol %, more preferably 45 to 68 mol %, based on the total amount of elements contained in the halogen element.

[0131] The halogen elements constituting the halogen-based solid electrolyte preferably include a base halogen element and a dopant element X2. The base halogen element may be Cl or Br, or may be Cl. The dopant element X2 is a halogen element other than the base halogen element. For example, when the base halogen element is Cl, the dopant element X2 may be at least one of Br and I, or may be Br.

[0132] The content of the base halogen element relative to the total amount of halogen elements is, for example, 80 mol % or more, 85 mol % or more, or 90 mol % or more.

[0133] The halogen-based solid electrolyte may contain a dopant element X3. The dopant element X3 is at least one of P and S. The content of the dopant element X3 in the halogen-based solid electrolyte 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 halogen-based solid electrolyte.

[0134] When the halogen-based solid electrolyte contains a dopant element X3, the halogen-based solid electrolyte may contain a tetravalent metal element or a semi-metal element as element group 1. Examples of the tetravalent metal element or semi-metal element include Zr, Ti, Hf, etc., and Zr may be used. In addition, the dopant element X2 may contain at least one of Hf and Mg.

[0135] The content of the dopant element X3 in the halogen-based solid electrolyte 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 semi-metal element. The content of the dopant element X3 in the halogen-based solid electrolyte 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 semi-metal element.

[0136] The halogen-based solid electrolyte may have a hexagonal crystal structure and a space group of P6 ３ The halogen-based solid electrolyte 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.

[0137] The halogen-based solid electrolyte 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 element group 1, 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.

[0138] Examples of the compound represented by formula (A) include compounds represented by the following formulas (1) to (3): α１ M1 β１ Z ６－δ１ X1 ε１１ X2 ε１２ ... (1) A α２ M2 β２ X2 ε２１ Z ６－γ２ X1 ε２２ ... (2) A α３ M2 β３ X1 ε３１ Z δ3 X3 ζ O η ...(3)

[0139] In formula (1), A is an alkali metal element, M1 is a trivalent metal element or a metalloid element, and Z is a halogen element. M1 preferably contains In. X1 and X2 are dopant elements X1 and X2, respectively, and specific examples thereof include those described above.

[0140] In formula (1), 2≦α1≦3.5 may be satisfied, or 2.5≦α1≦3 may be satisfied. 0.5≦β1≦1.1 may be satisfied, or 0.5≦β1≦1 may be satisfied. 0≦δ1≦1 may be satisfied, or 0≦δ1≦0.5 may be satisfied. 0≦ε11≦0.7 may be satisfied, or 0<ε11≦0.5 may be satisfied, or 0.01≦ε11≦0.3 may be satisfied. 0≦ε12≦0.7 may be satisfied, or 0<ε11≦0.5 may be satisfied, or 0.01≦ε11≦0.3 may be satisfied.

[0141] In formulas (2) and (3), A is an alkali metal element, M2 is a tetravalent metal element or semimetal element, and Z is a halogen element. M2 preferably contains Zr. X1 and X2 are dopant elements X1 and X2, respectively, and specific examples thereof include those described above.

[0142] In formula (2), 1.6≦α2≦2.5 may be satisfied, 1.8≦α2≦2.4 may be satisfied, or 2≦α2≦2.3 may be satisfied. 0<β2≦1.1 may be satisfied, 0.5≦β2≦1 may be satisfied, or 0.8≦β2≦1 may be satisfied. 0≦γ2<1 may be satisfied, 0.01≦γ2≦0.8 may be satisfied, 0.02≦γ2≦0.7 may be satisfied, 0.1≦γ2≦0.6 may be satisfied, or 0.2≦γ2≦0.6 may be satisfied. 0≦ε21≦0.7 may be satisfied, 0<ε21≦0.5 may be satisfied, or 0.01≦ε21≦0.3 may be satisfied. 0≦ε22≦0.8 may be satisfied, or 0<ε21≦0.6 may be satisfied. When X2 is iodine, 0.01≦ε21≦0.3 may be satisfied, or 0.015≦ε21≦0.1 may be satisfied.

[0143] In formula (3), X1 and X3 are the dopant element X1 and the dopant element X3, respectively, and specific examples thereof include those mentioned above.

[0144] In formula (3), 1.5≦α3≦3 may be satisfied, 1.8≦α3≦2.5 may be satisfied, 1.9≦α3≦2.3 may be satisfied, or 1.95≦α3≦2.2 may be satisfied. 0.5≦β3≦2 may be satisfied, 0.7≦β3≦1.4 may be satisfied, 0.8≦β3≦1.2 may be satisfied, or 0.9≦β3≦1.1 may be satisfied. 0.005≦ζ≦0.5 may be satisfied, 0.01≦ζ≦0.2 may be satisfied, 0.02≦ζ≦0.15 may be satisfied, or 0.025≦ζ≦0.10 may be satisfied. 3.5≦δ3≦5 may be satisfied, 3.7≦δ3≦4.3 may be satisfied, or 3.8≦δ3≦4.1 may be satisfied. 0.7≦η≦1.5 may be satisfied, 0.8≦η≦1.3 may be satisfied, or 0.9≦η≦1.1 may be satisfied.

[0145] The halogen-based solid electrolyte may be in the form of particles. In this case, the average particle size of the halogen-based solid electrolyte may be 1 to 50 μm. Furthermore, the particles of the halogen-based solid electrolyte may have an uneven structure with a size of 0.5 to 2 μm.

[0146] The method for producing a halogen-based solid electrolyte is not particularly limited, but may include, for example, a method including a step of ball milling raw materials. The product after ball milling may be annealed. Furthermore, when obtaining a hexagonal solid electrolyte material, the method for producing a halogen-based solid electrolyte may include a step of heating raw materials under a pressure of 1 GPa or more.

[0147] The raw materials are not particularly limited and may be, for example, alkali metal halides, chlorides of element group 1, 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).

[0148] The conditions for the ball mill are not particularly limited, but can be a rotation speed of 200 to 700 rpm and 10 to 100 hours. The rotation speed may be 250 to 600 rpm or 300 to 500 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. It is preferable to combine two or more sizes of balls, large and small. For example, balls with a diameter of 4 mm and balls with a diameter of 8 mm can be combined. In this case, it is preferable that the total weight of the 4 mm balls is greater than the total weight of the 8 mm balls. By performing the ball milling for the above time, the raw materials are thoroughly mixed, promoting the mechanochemical reaction and improving the ionic conductivity of the resulting compound.

[0149] 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.

[0150] 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.

[0151] <<Other Solid Electrolytes>> The solid electrolyte layer may contain a solid electrolyte other than the above-mentioned halogen-based solid electrolyte. A solid electrolyte other than the above-mentioned halogen-based solid electrolyte is referred to as an ion-conductive inorganic solid electrolyte. The ion-conductive inorganic solid electrolyte 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.

[0152] (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.

[0153] 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).

[0154] 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 M １ 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.

[0155] 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.

[0156] 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).

[0157] The oxide-based solid electrolyte may be a crystalline material or an amorphous material.

[0158] The oxide-based solid electrolyte is Li ６．６ La ３ Zr １．６ Ta ０．４ O １２ , Li ０．３３ La ０．５５ TiO ３ etc.

[0159] (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:

[0160] 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 Li２ S and P ２ S ５ The solid electrolyte also includes a mixture ratio of different.

[0161] 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).

[0162] 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 , Li ２ S-SiS ２ -Li ｘ MO ｙ (x and y are positive numbers; M is P, Si, Ge, B, Al, Ga, or In).

[0163] Li ２ S-GeS ２ Li-based compounds include ２ S-GeS ２ , Li ２ S-GeS ２ -P ２ S ５ Examples include:

[0164] The sulfide-based solid electrolyte may be a crystalline material or an amorphous material.

[0165] (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:

[0166] Examples of the ion-conductive inorganic solid electrolyte include compounds in which part or all of the Li in the compounds listed as specific examples of the oxide-based solid electrolyte, sulfide-based solid electrolyte, or hydride-based solid electrolyte is replaced with Na, K, Rb, or Cs.

[0167] The solid electrolyte layer may be formed from a solid electrolyte composition. The solid electrolyte composition essentially contains a halogen-based solid electrolyte, and may optionally contain an ion-conductive inorganic solid electrolyte other than the halogen-based solid electrolyte, and, as necessary, a polymer electrolyte, a binder resin, an organic solvent, an ionic liquid, etc.

[0168] The content of the halogen-based solid electrolyte may be 50% by mass or more, 55% by mass or more, 60% by mass or more, 65% by mass or more, or 70% by mass or more, relative to the total amount of the solid electrolyte composition. The content of the halogen-based solid electrolyte may be 95% by mass or less, 90% by mass or less, or 85% by mass or less, relative to the total amount of the solid electrolyte composition. The content of the halogen-based solid electrolyte may be 50 to 95% by mass, 55 to 90% by mass, or 60 to 85% by mass, relative to the total amount of the solid electrolyte composition.

[0169] The content of the halogen-based solid electrolyte may be 15 vol% or more, 25 vol% or more, 35 vol% or more, 40 vol% or more, 45 vol% or more, or 50 vol% or more, relative to the total amount of the solid electrolyte composition. The content of the halogen-based solid electrolyte may be 90 vol% or less, 80 vol% or less, 70 vol% or less, or 60 vol% or less, relative to the total amount of the solid electrolyte composition. The content of the halogen-based solid electrolyte may be 15 to 90 vol%, 25 to 80 vol%, or 35 to 60 vol%, relative to the total amount of the solid electrolyte composition. Unless otherwise specified, in this specification, volume percent is calculated based on the volume of each component contained in the solid electrolyte composition before mixing. When the mass percentage of each component contained in the solid electrolyte composition is known, volume percent may be the value obtained by dividing the mass percentage of each component by the density.

[0170] The halogen-based solid electrolyte may be one whose particle surface has been treated. Specific examples include treatment with an acid to remove the surface non-conductive layer or treatment to form a covalent bond with atoms. Examples of the acid include, but are not limited to, hydrochloric acid, nitric acid, and phosphoric acid.

[0171] (Other Materials) The solid electrolyte layer may contain a metal salt in a halogen-based solid electrolyte. The metal salt may be at least one of an alkali metal salt and an alkaline earth metal salt, and may be an alkali metal salt. The alkali metal salt is not particularly limited, but may be MF, MCl, MBr, MI, or MClO, where M is an alkali metal. ４ , MPF ６ , MBF ４ , M ２ SO ４ , M[(C ｈ F ２ｈ＋１ ) SO ３ ] (h is 0 to 3), M[(C ｈ F ２ｈ＋１ ) SO ２ ] ２ N (h is 0 to 3). When the polymer has the structural unit (A), M may be the same alkali metal element as the alkali metal element contained in the structural unit (A). M may be lithium, sodium, or potassium, or may be lithium.

[0172] The solid electrolyte layer may be a composite further containing other resins such as fluororesins, fabrics such as nonwoven fabrics, porous materials, viscosity adjusters, etc. As the fluororesin, a resin having a carbon chain as the main chain is preferred. 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).

[0173] <Negative Electrode Material> One aspect of the present invention is a negative electrode material including a negative electrode active material and a halogen-based solid electrolyte. The negative electrode active material in the negative electrode material includes phosphorus and absorbs or releases alkali metal ions when a voltage of 0.1 V or more is applied using an alkali metal as a counter electrode. The halogen-based solid electrolyte in the negative electrode material contains an alkali metal element, a metal element or a metalloid element other than the alkali metal element, and a halogen element.

[0174] The content of the negative electrode active material in the negative electrode material is not particularly limited, but is preferably in the range of 20% by mass or more and 80% by mass or less, and more preferably in the range of 35% by mass or more and 75% by mass or less, based on the total mass of the negative electrode active material, the solid electrolyte including the halogen-based solid electrolyte, the conductive additive, and the binder.

[0175] The halogen-based solid electrolyte in the negative electrode material can be the same as the halogen-based solid electrolyte in the description of the battery of this embodiment above. The content of the halogen-based solid electrolyte in the negative electrode material is not particularly limited, but is preferably in the range of 20% by mass to 80% by mass, more preferably 25% by mass to 70% by mass, based on the total mass of the negative electrode active material, the solid electrolyte containing the halogen-based solid electrolyte, the conductive additive, and the binder.

[0176] The negative electrode material may also contain an organic solvent. The organic solvent may be an aprotic solvent, such as at least one selected from the group consisting of carbonate-based solvents, fluorine-based solvents, and ether-based solvents.

[0177] Examples of carbonate solvents include chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; and cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate.

[0178] Examples of the ether solvent include cyclic ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, and 1,3-dioxolane; and chain ethers such as 1,2-diethoxyethane and ethoxymethoxyethane.

[0179] Examples of the fluorine-based solvent include hydrofluorocarbons such as perfluorooctane; hydrofluoroethers such as methyl nonafluorobutyl ether and ethyl nonafluorobutyl ether; and hydrofluoroolefins such as 1,3,3,3-tetrafluoropropene.

[0180] Examples of the solvent include aprotic solvents such as dimethyl sulfoxide (DMSO); amide solvents such as dimethylformamide (DMF) and dimethylacetamide (DMA).

[0181] The organic solvent may be used alone or as a mixed solvent containing two or more organic solvents. When a mixed solvent is used, for example, the organic solvent may be a mixed solvent containing two or more carbonate solvents, a mixed solvent containing two or more cyclic carbonates, or a mixed solvent containing ethylene carbonate and propylene carbonate.

[0182] The content of the organic solvent may be 1 to 45% by mass, 4 to 40% by mass, or 7 to 30% by mass, based on the total amount of the inorganic material. The content of the organic solvent may be 1 to 70% by volume, 4 to 60% by volume, or 20 to 50% by volume, based on the total amount of the inorganic material. The mass ratio of the polymer to the organic solvent in the inorganic material may be 1:0.5 to 1:3, or 1:1 to 1:2.5.

[0183] The battery having the above-described configuration ensures good ionic conduction with the negative electrode active material, resulting in a highly durable battery. Furthermore, the negative electrode material and laminate having the above-described configuration provide a negative electrode material and laminate that can easily ensure good ionic conduction with the negative electrode active material.

[0184] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to these examples. The shapes and combinations of the components shown in the above examples are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0185] For example, although the above embodiment has been described with reference to a lithium ion secondary battery, an alkali metal may be used as the metal ion absorbed or released by the negative electrode active material. The alkali metal to be used is preferably lithium or sodium, and more preferably lithium.

[0186] When sodium is used as the alkali metal, the negative electrode active material is a material that absorbs or releases sodium ions when a voltage of 0.1 V or more is applied using metallic sodium as the counter electrode.

[0187] Even if the metal species is changed from lithium to another alkali metal such as sodium, the halogen-based solid electrolyte has the ability to preferentially conduct alkali metal ions, and therefore the movement of alkali metal ions is less likely to be hindered, and a reaction with the negative electrode occurs smoothly. This makes it possible to provide a battery that ensures good ion conduction with the negative electrode active material and is highly durable, as well as a negative electrode material and a laminate that easily ensure good ion conduction with the negative electrode active material.

[0188] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0189] <Production of each material>

[0190] (Production of Negative Electrode Active Material 1) Black phosphorus manufactured by Rasa Industries and CSCNT (cup-stacked carbon nanotubes: manufactured by GSI Creos Co., Ltd.) were weighed out in a mass ratio of P:C = 6:4 (total amount 0.5 g) and mixed using a ball mill under the following conditions to obtain PC material 1. A TEM photograph of the obtained PC material 1 was taken, and it was confirmed that it had a core-shell structure in which the surface of a core particle containing phosphorus atoms was covered with a carbon film, as shown in FIG.

[0191] (Ball mill mixing conditions) Apparatus: Retsch PM-100 Container: ZrO ２ 50 mL container Media: ZrO ２ 5 mm diameter ball manufactured by 60 g Atmosphere: Argon gas sealed Sample amount: 0.5 g as a mixture of raw materials Ball / powder ratio: 120 (weight ratio) Mixing time: 12 hours

[0192] (Production of Negative Electrode Active Material 2) Black phosphorus manufactured by Rasa Industries, CSCNT (cup-stacked carbon nanotubes: manufactured by GSI Creos Co., Ltd.), and PVdF (KF polymer #9300: manufactured by Kureha) were weighed out in a mass ratio of P:C:PVdF = 6:4:0.75 (total amount 0.5 g), and mixed using a ball mill under the following conditions to obtain a PVdF-containing PC material.

[0193] (Ball mill mixing conditions) Apparatus: Retsch PM-100 Container: ZrO ２ 50 mL container Media: ZrO ２ 5 mm diameter ball manufactured by 60 g Atmosphere: Argon gas sealed Sample amount: 0.5 g as a mixture of raw materials Ball / powder ratio: 120 (weight ratio) Mixing time: 12 hours

[0194] 0.2 g of NMP was added to the obtained PVdF-containing PC material, and the mixture was kneaded in an agate mortar so that the PVdF was dissolved and uniformly mixed, and then the mixture was dried in vacuum at 80°C to obtain a powdered PC material 2 coated with PVdF.

[0195] The obtained PC material 2 was charged at a charge rate of 0.2 C using lithium metal as the counter electrode. As a result, the average charge potential of PC material 2 relative to the capacity (mAh / g) during charging was 0.1 V or more. It was confirmed that the obtained PC material 2 is a material that absorbs lithium ions when lithium (alkali metal) is used as the counter electrode and a voltage of 0.1 V or more is applied.

[0196] The resulting PC material 2 had a phosphorus atom content of 60% by mass and a carbon atom content of 40% by mass. Because the container used in the above-mentioned production was extremely airtight, it was determined that the content of each atom in PC material 2 was equal to the raw material ratio.

[0197] Furthermore, the obtained PC material 1 or PC material 2 has a weight loss rate WL at a measurement temperature of 620°C obtained by thermogravimetry under the following conditions: ６２０ and the weight loss rate WL at a measurement temperature of 780 ° C. ７８０ Relative to WL ６２０ / WL ７８０However, it was 0.58.

[0198] (Thermogravimetric Measurement) 10 mg of PC material 1 or PC material 2 was precisely weighed to prepare a sample, and the weight change was measured using a thermogravimetric measuring device when the sample was heated from 50°C to 780°C at a temperature increase rate of 10°C / min under a nitrogen gas flow.

[0199] (Weight Loss Rate) The ratio of the weight of the sample at the measurement temperature to the weight of the precisely weighed sample is defined as the weight loss rate (wt %) at the measurement temperature.

[0200] Furthermore, the obtained PC material 1 or PC material 2 has a weight loss rate WL at a measurement temperature of 300°C obtained by the above-mentioned thermogravimetry. ３００ and the weight loss rate WL at a measurement temperature of 600 ° C. ６００ Relative to WL ３００ / WL ６００ However, it was -0.02.

[0201] The obtained PC material 1 or PC material 2 was measured according to the above-mentioned (XPS spectrum measurement conditions), and a peak indicating a bond between a phosphorus atom and a carbon atom was confirmed in each case.

[0202] The obtained PC material 1 or PC material 2 was measured according to the above-mentioned (XRD profile measurement conditions), and in the XRD profile, the intensity I at 2θ=20° was ２０ is 3680, and the intensity I at 2θ = 26.3° ２６．３ is 3350, and the intensity at 2θ = 40° is I ４０ was 2008. In addition, |P| / |B| was 1.17. PC material 1 or PC material 2 exhibiting these values ​​satisfies the following formulas (1) to (3): |P| / |B|<2 ... (1) P=I ２６．３ -I ４０ ...(2) B = (I ２０ -I ４０ ) × (26.3 - 40) / (20 - 40) ... (3)

[0203] (Halogen-based solid electrolyte) The following halogen-based solid electrolyte 1 was used as the halogen-based solid electrolyte. ３ ScCl ６ (γ-Li３ ScCl ６ ) was synthesized by the following method. ３ ScCl ６ To synthesize ３ The mixture was mixed in a glove box under a nitrogen atmosphere. Then, the mixture was pressed into a pellet with gold foil as a protective material. The pellet was inserted into a sleeve tube with a handmade gold crucible and a boron nitride (BN) lid. Next, the sample and the sleeve were inserted into a graphite tube and sealed in a pyrophyllite cube for high-pressure reaction. The sample cell was pressed to reach 5 GPa in 1 hour and then heated to 1000 °C in 3 hours. After holding at this temperature for 3 hours, the sample was quenched to room temperature within 5 minutes, and then the pressure was released and reached atmospheric pressure in 2 hours. This resulted in the production of a halogen-based solid electrolyte 1, a lithium-containing chloride (γ-Li ３ ScCl ６ ) was obtained.

[0204] <Powder X-ray Diffraction Measurement> The crystal structure of the obtained halogen-based solid electrolyte 1 was evaluated by powder X-ray diffractometry at 25° C. As a result, the halogen-based solid electrolyte 1 was found to belong to the space group P6 ３ It was confirmed that the sample had a diffraction peak attributable to the mc crystal structure. The powder X-ray diffraction measurement was carried out under the following conditions. The sample space was protected with polyimide tape in a glove box to prevent the sample from coming into direct contact with the atmosphere. Measurement equipment: SmartLab (manufactured by Rigaku Corporation) X-ray generator: CuKα radiation source, voltage 40 kV, current 50 mA X-ray detector: Semiconductor detector Measurement range: Diffraction angle 2θ = 5° to 80° Scan speed: 2.5° / min

[0205] [Halogen-based solid electrolyte 2] As the halogen-based solid electrolyte 2, Li ２．８９ In ０．９１ Zr ０．０９６ Cl ６was produced by the following method: Ball mill: First, 0.4257 g of LiCl, 0.4257 g of InCl were mixed in an argon atmosphere having a dew point of −70° C. or less (hereinafter referred to as a dry argon atmosphere). ３ 0.7044 g, ZrCl ４ The raw material was prepared by weighing 0.0784 g. The raw material was placed in a zirconia pot for a planetary ball mill described below, and 65 g of zirconia balls with a diameter of 4 mm were added. The raw material was treated for 48 hours at 380 rpm to cause a mechanochemical reaction, thereby obtaining a crude composition. Planetary ball mill apparatus: PM 400 manufactured by Verder Scientific K.K. Annealing The crude composition obtained above was heated in an argon atmosphere at 230°C for 5 hours, so that the charged composition became Li ２．８９ In ０．９１ Zr ０．０９６ Cl ６ Thus, a halogen-based solid electrolyte 2 was obtained.

[0206] <Evaluation of Crystal Structure> The crystal structure of the obtained halogen-based solid electrolyte 2 was evaluated by powder X-ray diffraction measurement at 25°C. The powder X-ray diffraction measurement was carried out under the following conditions. Measurement apparatus: Ultima IV (manufactured by Rigaku Corporation) X-ray generator: CuKα radiation source, voltage 40 kV, current 40 mA X-ray detector: Scintillation counter Measurement range: Diffraction angle 2θ = 10° to 80° Scan speed: 4° / min Sample preparation: Powdered by mortar grinding As a result of the analysis, the crystal structure of the halogen-based solid electrolyte 2 was assigned to the monoclinic space group C2 / m. The half-width of the reflection peak having the largest peak height in the 2θ range of 10 to 18° was 0.25°.

[0207] [Halogen-based solid electrolyte 3] As the halogen-based solid electrolyte 3, Li ２．１ Zr ０．９５ Mg ０．０５ Cl ３．９ O (PO ４ ) ０．０３３ was produced by the following method. ２ O, ZrCl ４ , MgCl ２ , and Li３ P.O. ４ Using Li ２．１ Zr ０．９５ Mg ０．０５ Cl ３．９ O (PO ４ ) ０．０３３ The compounding ratio of the raw materials was adjusted so as to obtain the composition of the feed, and ball milling was carried out under the following conditions: Ball mill: In an argon atmosphere having a dew point of −70° C. or less (hereinafter referred to as a dry argon atmosphere), Li was used as the raw material. ２ O, ZrCl ４ , MgCl ２ , and Li ３ P.O. ４ Using Li ２．１ Zr ０．９５ Mg ０．０５ Cl ３．９ O (PO ４ ) ０．０３３ The raw materials were prepared by adjusting the blending ratio of the raw materials and weighing them so that the total amount was 1.2 g. The raw materials were placed in a 50 ml zirconia pot for the planetary ball mill described below, and 65 g of zirconia balls with a diameter of 4 mm were added. The raw materials were treated for a mechanochemical reaction at 300 rpm for 24 hours, yielding a halogen-based solid electrolyte 3. 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.

[0208] [Oxide-based solid electrolyte 4] The oxide-based solid electrolyte is a garnet-type oxide solid electrolyte Li manufactured by Toshima Manufacturing Co., Ltd. ６．６ La ３ Zr １．６ Ta ０．４ O １２ was used.

[0209] [Example 1] (Preparation of Evaluation Battery) (1) Preparation of Negative Electrode 1 The PC material 1 obtained in the above (Preparation of Negative Electrode Active Material), conductive material, and binder were weighed to prepare a mixture of [PC material 1]:[conductive material]:[binder]:=84:10:6 (mass ratio). The materials used were as follows. Binder: vinylidene fluoride PVdF (Solef 5130 (manufactured by Solvay)) Conductive material: carbon nanofiber VGCF (vapor grown carbon fiber)

[0210] The mixture was kneaded with a solvent (N-methyl-2-pyrrolidone (NMP)) using an agate mortar to prepare a negative electrode slurry. Since the viscosity of the slurry changes depending on the temperature of the slurry, the amount of solvent (slurry concentration) was adjusted to adjust the viscosity. At this time, the allowable range for the content of solids in the negative electrode slurry (the total of the PC material 1, the conductive material, and the binder) was set to 30 to 60 mass%.

[0211] The negative electrode slurry was applied to a copper foil current collector using a doctor blade, and then dried at 80°C for 1 hour to remove the solvent, obtaining a laminate. The obtained laminate was pressed at 10 MPa for 10 seconds and then further dried in vacuum at 150°C for 12 hours to obtain a negative electrode.

[0212] The preparation of the negative electrode slurry and the preparation of the negative electrode were carried out in a glove box in an argon atmosphere.

[0213] (2) Fabrication of Lithium Ion Secondary Battery A lithium secondary battery (coin-type battery R2032) of Example 1 was fabricated by the following method by combining a negative electrode 1, a counter electrode (Li—In alloy), and a halogen-based solid electrolyte 1. The lithium secondary battery was assembled in a glove box under an argon atmosphere.

[0214] <Fabrication of Lithium Secondary Battery> 100 mg of the halogen-based solid electrolyte 1 and the negative electrode 1 were stacked in this order in an insulating cylinder with an inner diameter of 10 mm to obtain a laminate. A pressure of 370 MPa was applied to the laminate to form a first electrode (a layer of the negative electrode 1) and a first solid electrolyte layer (a layer of the solid electrolyte 1). Next, the first solid electrolyte layer and the sulfide solid electrolyte Li ６ P.S. ５A laminate was obtained by applying a pressure of 370 MPa to the laminate, forming a second solid electrolyte layer. 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 then 2 mg of Li foil was placed in contact with the In foil, forming a laminate. A pressure of 370 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 lithium secondary battery of Example 1 was thus obtained.

[0215] [Example 2] (1) Preparation of Negative Electrode 2 The PC material 2 obtained in the above (Production of Negative Electrode Active Material) and the conductive material were weighed to prepare a mixture of [PC material 2]:[Conductive material] = 90:10 (mass ratio). The materials used were as follows. Conductive material: carbon nanofiber VGCF (vapor grown carbon fiber)

[0216] The mixture was kneaded with a solvent (N-methyl-2-pyrrolidone (NMP)) using an agate mortar to prepare a negative electrode slurry. Since the viscosity of the slurry changes depending on the temperature of the slurry, the amount of solvent (slurry concentration) was adjusted to adjust the viscosity. At this time, the allowable range for the content of solids in the negative electrode slurry (the total of the PC material 2, the conductive material, and the binder) was set to 30 to 60 mass%.

[0217] The negative electrode slurry was applied to a copper foil current collector using a doctor blade, and then dried at 80°C for 1 hour to remove the solvent, obtaining a laminate. The obtained laminate was pressed at 10 MPa for 10 seconds and then further dried in vacuum at 150°C for 12 hours to obtain a negative electrode.

[0218] The preparation of the negative electrode slurry and the preparation of the negative electrode were carried out in a glove box in an argon atmosphere.

[0219] A lithium secondary battery was obtained in the same manner as in Example 1, except that the negative electrode 2 was used.

[0220] Example 3 A lithium secondary battery of Example 3 was produced under the same conditions as in Example 2, except that halogen-based solid electrolyte 2 was used.

[0221] Example 4 A lithium secondary battery of Example 4 was produced under the same conditions as in Example 2, except that Solid Electrolyte 3 was used for the halogen-based solid electrolyte layer.

[0222] [Example 5] <Preparation of Secondary Battery> In a dry argon atmosphere, the halogen-based solid electrolyte 1, the PC material 1 obtained in the above (Production of Negative Electrolyte Active Material), and the conductive material were weighed to prepare a mixture of [halogen-based solid electrolyte 1]:[PC material 1]:[conductive material]=50:45:5 (mass ratio). The materials used were as follows. Conductive material: carbon nanofiber VGCF (vapor grown carbon fiber)

[0223] In an insulating cylinder with an inner diameter of 10 mm, 100 mg of halogen-based solid electrolyte 1 and the above mixture were stacked in this order to obtain a laminate. A pressure of 370 MPa was applied to the laminate to form a first electrode and a first solid electrolyte layer (a layer of halogen-based solid electrolyte 1). Next, the first solid electrolyte layer and the sulfide solid electrolyte Li ６ P.S. ５ A laminate was obtained by applying a pressure of 370 MPa to the laminate, forming a second solid electrolyte layer. 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 so that it was in contact with the second solid electrolyte layer, and then 2 mg of Li foil was placed so that it was in contact with the In foil, forming a laminate. A pressure of 370 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 5 was thus obtained.

[0224] Comparative Example 1 A lithium secondary battery of Comparative Example 1 was produced under the same conditions as in Example 2, except that oxide solid electrolyte 4 was used.

[0225] (Measurement of charge / discharge capacity: Measurement condition 1) Using the fabricated lithium secondary battery, a charge / discharge test was carried out under the following conditions while maintaining the temperature at 25°C. Here, the theoretical capacity of phosphorus was set to 1800 mAh / g, and the 1C current for charging or discharging the electrode capacity in 1 hour was set to 1800 mA / g. In the charge / discharge test, the 1C current was calculated from the mass of phosphorus contained in the negative electrode. The definition of 1C in the examples is the same hereinafter.

[0226] Minimum charging voltage: -0.6 (minus 0.6) V Charging current: 0.1 C (1 C = 1800 mA / g) Maximum discharging voltage: 1.9 V Discharging current: 0.1 C (1 C = 1800 mA / g) The temperature was 60°C, and three cycles were performed.

[0227] 6 is a charge / discharge curve showing the results of a charge / discharge test carried out under measurement condition 1 of Example 1. As shown in FIG. 6, it was confirmed that the lithium secondary battery of Example 1 had a charge / discharge capacity exceeding 1000 mAh / g in each cycle (cycles 1 to 3).

[0228] (Measurement of charge / discharge capacity: Measurement condition 2) Using the fabricated lithium secondary battery, a charge / discharge test was carried out under the following conditions while maintaining the temperature at 25°C. Here, the theoretical capacity of phosphorus was set to 1800 mAh / g, and the 1C current for charging or discharging the electrode capacity in 1 hour was set to 1800 mA / g. In the charge / discharge test, the 1C current was calculated from the mass of phosphorus contained in the negative electrode. The definition of 1C in the examples is the same hereinafter.

[0229] Minimum charging voltage: -0.1 (minus 0.1) V Charging current: 0.1 C (1 C = 1800 mA / g) Maximum discharging voltage: 1.9 V Discharging current: 0.1 C (1 C = 1800 mA / g) The temperature was 60°C, and the cycle characteristics were evaluated for each example.

[0230] In the graphs showing the results of the charge / discharge tests below, the horizontal axis represents capacity (unit: mAh / g) and the vertical axis represents applied voltage (unit: V).

[0231] Fig. 7 shows charge / discharge curves showing the results of the charge / discharge test under measurement condition 2 in Example 1. Fig. 7 shows excerpts of the charge / discharge curves, 1st cycle, 5th cycle, and 10th cycle, showing the results of the charge / discharge test under measurement condition 2 in Example 1. As shown in Fig. 7, it was confirmed that the lithium secondary battery of Example 1 had a charge / discharge capacity of more than 500 mAh / g in each cycle.

[0232] 8 is a plot of the charge / discharge capacity and coulombic efficiency for each cycle in the cycle test under measurement condition 2. It was confirmed that charge / discharge capacity was obtained up to 10 cycles.

[0233] 9 shows the results of a charge-discharge test of the lithium secondary battery of Example 2 under Measurement Condition 2. As shown in FIG. 9, the lithium secondary battery of Example 2 was confirmed to be functional, with a charge-discharge capacity of 900 mAh / g or more up to 10 cycles.

[0234] 10 shows the results of the first cycle of the charge-discharge test for the lithium secondary battery of Example 3, which was performed under the conditions of measurement condition 2. As shown in FIG. 10, the lithium secondary battery of Example 3 obtained a discharge capacity of 42.5 mAh / g, and it was confirmed that the battery performed charge and discharge operations.

[0235] 11 shows the results of operation of the lithium secondary battery of Example 4 under the conditions of measurement condition 2. As shown in FIG. 11, the lithium secondary battery of Example 4 obtained a charge / discharge capacity exceeding 100 mAh / g through 10 cycles.

[0236] Fig. 12 shows the results of operation of the lithium secondary battery of Example 5 under the conditions of measurement condition 2. As shown in Fig. 12, it was confirmed that the lithium secondary battery of Example 5 could be charged and discharged, and a charge / discharge capacity exceeding 1500 mAh / g was obtained.

[0237] 13 shows the results of charging and discharging the lithium secondary battery of Comparative Example 1 under Measurement Condition 2. The obtained charge and discharge capacity was 0.01 mAh / g or less, and the battery was hardly able to perform charge and discharge operations.

[0238] As is clear from FIGS. 6 to 12, the lithium secondary battery of Comparative Example 1 had a charge / discharge capacity of 0.01 mAh / g or less, whereas the lithium secondary batteries of Examples 1 to 5 were able to obtain comparatively good charge / discharge capacities.

[0239] From the above, it was confirmed that the present invention is useful.

[0240] 50...particle, 51...core particle, 52...carbon film, 100...laminated body, 120...negative electrode, 121...negative electrode active material layer, 130...solid electrolyte layer

Claims

1. A battery comprising: a negative electrode having a negative electrode active material layer; and a solid electrolyte layer in contact with the negative electrode active material layer, wherein the negative electrode active material layer contains a negative electrode active material that contains phosphorus and that absorbs or releases ions of an alkali metal when a voltage of 0.1 V or more is applied using an alkali metal as a counter electrode, and either or both of the negative electrode active material layer and the solid electrolyte layer contain a halogen-based solid electrolyte, and the halogen-based solid electrolyte contains an alkali metal element, a metal element or a metalloid element other than an alkali metal element, and a halogen element.

2. The battery according to claim 1, wherein both the negative electrode active material layer and the solid electrolyte layer contain the halogen-based solid electrolyte.

3. The battery according to claim 1 or 2, wherein the negative electrode active material is a phosphorus-carbon composite material containing phosphorus atoms and carbon atoms.

4. The phosphorus atom content in the phosphorus-carbon composite material is 10% by mass or more and 95% by mass or less, the carbon atom content in the phosphorus-carbon composite material is 5% by mass or more and 90% by mass or less, and the weight loss rate WL at a measurement temperature of 620°C obtained by thermogravimetry under the following conditions is ６２０ and the weight loss rate WL at a measurement temperature of 780°C ７８０ Relative to WL ６２０ / WL ７８０ is 0.1 or more and 0.9 or less. (Thermogravimetric measurement) 10 mg of the phosphorus-carbon composite material is precisely weighed out to prepare a sample, and a thermogravimetric measuring device is used to measure the change in weight when the sample is heated from 50° C. to 780° C. at a temperature increase rate of 10° C. / min in a nitrogen stream. (Weight reduction rate) The ratio of the weight of the sample at the measurement temperature to the weight of the precisely weighed sample is defined as the weight reduction rate (wt %) at the measurement temperature.

5. Weight loss rate WL at a measurement temperature of 300°C obtained by the above thermogravimetry ３００ and the weight loss rate WL at a measurement temperature of 600°C ６００ Relative to WL ３００ / WL ６００ The battery according to claim 4, wherein the value is greater than or equal to -0.1 and less than or equal to 0.

1.

6. The battery according to claim 4, having a peak in an XPS spectrum indicating a bond between a phosphorus atom and a carbon atom.

7. In the XRD profile measured using CuKα radiation, the intensity I at 2θ = 20° ２０ , Intensity I at 2θ=26.3° ２６．３ , and the intensity I at 2θ=40° ４０ The battery according to claim 4, wherein |P| / |B|<2 ... (1) P=I satisfies the following formulas (1) to (3). ２６．３ -I ４０ ... (2) B = (I ２０ -I ４０ ) × (26.3 − 40) / (20 − 40) … (3) 8. The battery according to claim 4, comprising: a core particle containing a phosphorus atom; and a carbon coating covering the surface of the core particle.

9. A negative electrode material comprising a negative electrode active material and a halogen-based solid electrolyte, wherein the negative electrode active material contains phosphorus and absorbs or releases ions of the alkali metal when a voltage of 0.1 V or more is applied using an alkali metal as a counter electrode, and the halogen-based solid electrolyte contains an alkali metal element, a metal element or a metalloid element other than the alkali metal element, and a halogen element.

10. A laminate comprising: a negative electrode having a negative electrode active material layer; and a solid electrolyte layer in contact with the negative electrode active material layer, wherein the solid electrolyte layer contains a halogen-based solid electrolyte, the halogen-based solid electrolyte contains an alkali metal element, a metal element or a metalloid element other than an alkali metal element, and a halogen element, and the negative electrode active material contained in the negative electrode active material layer absorbs or releases ions of the alkali metal when a voltage of 0.1 V or more is applied using an alkali metal as a counter electrode.

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