Fluoride ion battery and method for manufacturing the same

Abstract

To provide a fluoride ion battery having a negative electrode active material capable of achieving high charge / discharge capacity, and a manufacturing method thereof.SOLUTION: A disclosed fluoride ion battery has LaxC(1.00-x) as negative electrode active material and 0.00<x<1.00. A disclosed manufacturing method includes a step of discharging a fluoride ion battery precursor that has LaxC(1.00-x) as a negative electrode active material, and 0.00<x<1.00 until the upper limit potential of the negative electrode becomes 2.5 to 3.5 V vs Pb / PbF2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a fluoride ion battery and a method for manufacturing the fluoride ion battery.

Background Art

[0002] Patent Document 1 discloses a fluoride ion battery having a positive electrode active material layer, a negative electrode active material layer, and an electrolyte layer formed between the positive electrode active material layer and the negative electrode active material layer, wherein the negative electrode active material layer contains a negative electrode active material containing Si element and La element, and a solid electrolyte containing La element, Ba element, and F element.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a fluoride ion battery, it is required to achieve a high charge-discharge capacity.

[0005] An object of the present disclosure is to provide a fluoride ion battery having a negative electrode active material capable of achieving a high charge-discharge capacity and a method for manufacturing the same.

Means for Solving the Problems

[0006] The inventor has found that the above problems can be achieved by the following means: 《Aspect 1》 La as a negative electrode active material x C (1.00-x) A fluoride ion battery having and 0.00 < x < 1.00. 《Aspect 2》 The fluoride ion battery according to Embodiment 1, wherein 0.30 ≦ x ≦ 0.45. <<Embodiment 3>> The fluoride ion battery according to Embodiment 1 or 2, having a lanthanoid fluoride as a solid electrolyte. <<Embodiment 4>> The fluoride ion battery according to any one of Embodiments 1 to 3, having a charge-discharge capacity of 300 mAh / g or more. <<Embodiment 5>> La as a negative electrode active material x C (1.00-x) A method for manufacturing a fluoride ion battery, comprising discharging a fluoride ion battery precursor having 0.00 < x < 1.00 until the upper limit potential of the negative electrode becomes 2.5 to 3.5 V vs Pb / PbF2. <<Embodiment 6>> Before performing the discharge until the upper limit potential of the negative electrode becomes 2.5 V to 3.5 V vs Pb / PbF2, charging and discharging are performed so that the upper limit potential of the negative electrode becomes -0.5 V to 0.5 V vs Pb / PbF2 and the lower limit potential of the negative electrode becomes -3.0 V to -2.0 V vs Pb / PbF2. A method for manufacturing a fluoride ion battery according to Embodiment 5.

Advantages of the Invention

[0007] According to the present disclosure, it is possible to provide a fluoride ion battery having a negative electrode active material capable of realizing a high charge-discharge capacity and a method for manufacturing the same.

Brief Description of the Drawings

[0008] [Figure 1] FIG. 1 is a schematic diagram of a fluoride ion battery according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a graph showing the charge-discharge characteristics of the fluoride ion battery of Example 1. [Diagram 3] FIG. 3 is a graph showing the charge-discharge characteristics of the fluoride ion battery of Example 2. [Figure 4] FIG. 4 is a graph showing the charge-discharge characteristics of the fluoride ion battery of Comparative Example 1. [Diagram 5]FIG. 5 is a graph showing the charge / discharge characteristics of the fluoride ion battery of Example 3. [Figure 6] FIG. 6 is a graph showing the charge / discharge characteristics of the fluoride ion battery of Example 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present disclosure will be described in detail. Note that the present disclosure is not limited to the following embodiments, and various modifications can be made within the scope of the present disclosure.

[0010] Fluoride-ion battery The disclosed fluoride ion battery uses La as a negative electrode active material. x C (1.00-x) and 0.00 <x<1.00である。

[0011] The fluoride ion battery of the present disclosure has La as a negative electrode active material. x C (1.00-x) has a higher charge / discharge capacity than lanthanum alone.

[0012] In addition, La as the negative electrode active material x C (1.00-x) can undergo an oxidation-reduction reaction at a more noble potential than lanthanum alone. The oxidation-reduction reaction of the active material at a more noble potential can broaden the range of options for the type of solid electrolyte when the solid electrolyte is contained in the negative electrode.

[0013] The charge / discharge capacity of the fluoride ion battery of the present disclosure can be 300 mAh / g or more. x C (1.00-x) A fluoride ion battery having a charge / discharge capacity of 300 mAh / g or more can be manufactured, for example, by the manufacturing method of the present disclosure.

[0014] FIG. 1 is a schematic diagram of a fluoride-ion battery 1 according to a first embodiment of the present disclosure.

[0015] The fluoride ion battery 1 according to the first embodiment of the present disclosure has a structure in which a positive electrode current collector layer 10, a positive electrode active material layer 20, an electrolyte layer 30, a negative electrode active material layer 40, and a negative electrode current collector layer 50 are laminated in this order. Here, the negative electrode active material layer 40 contains La as a negative electrode active material x C (1.00-x) and has it.

[0016] Note that the fluoride ion battery of the present disclosure may be a liquid battery or a solid battery, particularly an all-solid battery. Further, the fluoride ion battery in the present disclosure may be a primary battery or a secondary battery. Examples of the shape of the fluoride ion battery in the present disclosure include coin type, laminate type, cylindrical type, and rectangular type.

[0017] 〈Negative electrode active material〉 The fluoride ion battery of the present disclosure contains La as a negative electrode active material x C (1.00-x) and has it. Here, 0.00 < x < 1.00. Usually, the negative electrode active material in a fluoride ion battery releases fluorine during charging and absorbs fluorine during discharging. In other words, the negative electrode active material contained in the fluoride ion battery of the present disclosure is La x C (1.00-x) in a completely defluorinated state, and depending on the charge and discharge state of the fluoride ion battery, it can further contain F.

[0018] La x C (1.00-x) In, it is particularly preferable that 0.30 ≦ x ≦ 0.45.

[0019] When x is 0.30 to 0.45, La x C (1.00-x) has a particularly high charge and discharge capacity. This is because when x is in this range, the proportion of the metal carbide part in the La x C (1.00-x) particles increases. When x is less than 0.30 or more than 0.45, the proportion of single carbon or single lanthanum present in the crystal increases. In particular, the closer x is to 1.00, the closer its properties are to those of single La.

[0020] x may be 0.30 or more, 0.31 or more, 0.32 or more, or 0.33 or more, and may be 0.45 or less, 0.43 or less, 0.41 or less, or 0.40 or less.

[0021] The negative electrode active material may be in the form of particles, for example.

[0022] The average particle size (D50) of the negative electrode active material may be, for example, 0.01 to 50 μm. The average particle size (D50) of the negative electrode active material may be 0.01 μm or more, 0.05 μm or more, or 0.10 μm or more, and may be 50 μm or less, 25 μm or less, or 10 μm or less.

[0023] The average particle size (D50) of the negative electrode active material can be determined, for example, from the results of particle size distribution measurement by a laser diffraction scattering method.

[0024] The method for producing the negative electrode active material may be, for example, an arc melting method using La and C as raw materials, but is not limited thereto.

[0025] <Solid electrolyte> Fluoride ion batteries of the present disclosure can contain a solid electrolyte. The solid electrolyte can be any solid electrolyte that can be used in a fluoride ion battery.

[0026] Examples of the solid electrolyte include fluorides of lanthanoid elements such as La and Ce, fluorides of alkali metal elements such as Li, Na, K, Rb, Cs, and fluorides of alkaline earth elements such as Ca, Sr, Ba, etc. The solid electrolyte may also be a fluoride containing a plurality of lanthanoid elements, alkali metal elements, and alkaline earth elements.

[0027] Specific examples of solid electrolytes include La (1-x) Ba x F (3-x) (0≦x≦1), Pb (2-x) Sn xF4(0≦x≦2), Ca (2-x) Ba x F4(0≦x≦2) and Ce (1-x) BaxF (3-x) (0≦x≦1). Each of the x's may be greater than 0, greater than or equal to 0.3, greater than or equal to 0.5, or greater than or equal to 0.9. Each of the x's may be smaller than 1, less than or equal to 0.9, less than or equal to 0.5, or less than or equal to 0.3. Note that "x" described in the specific examples of the solid electrolyte is of course the same as La, which is the negative electrode active material of the present disclosure. x C (1.00-x) are different and independent values ​​from "x" in

[0028] The shape of the solid electrolyte is not particularly limited, but may be, for example, particulate.

[0029] The fluoride ion batteries of the present disclosure are particularly useful when they have a lanthanide fluoride as a solid electrolyte, i.e., a fluoride of a lanthanide element.

[0030] Lanthanide fluorides have relatively high fluoride ion conductivity, but they are reductively decomposed at the same potential as lanthanum to precipitate metallic lanthanum. Therefore, when a lanthanide fluoride is further used as a solid electrolyte in a fluoride ion battery using metallic lanthanum as the negative electrode active material, the ion conduction path is easily blocked.

[0031] In contrast, the fluoride ion battery of the present disclosure uses, as the negative electrode active material, La, which exhibits an oxidation-reduction reaction at a more noble potential than metallic lanthanum. x C (1.00-x) By adopting this, it is possible to suppress the reductive decomposition of the lanthanide fluoride during the use of the battery.

[0032] The lanthanoid fluoride as the solid electrolyte may be present in any of the positive electrode active material layer, the electrolyte layer, and the negative electrode active material layer, but is particularly preferably present in the negative electrode active material layer.

[0033] <Other configurations> In addition to the above configuration, the fluoride ion battery of the present disclosure may have, for example, a positive electrode collector layer, a positive electrode active material layer, an electrolyte layer, a negative electrode active material layer, and a negative electrode collector layer. The fluoride ion battery of the present disclosure may also have a battery case that houses these components.

[0034] (Positive electrode current collector layer) Examples of the material of the positive electrode current collector layer include stainless steel (SUS), aluminum, nickel, iron, titanium, platinum, and carbon. Examples of the shape of the positive electrode current collector layer include a foil shape, a mesh shape, and a porous shape.

[0035] (Cathode active material layer) The positive electrode active material layer in the present disclosure contains a positive electrode active material, and optionally a solid electrolyte, a conductive additive, and a binder.

[0036] The positive electrode active material in the present disclosure is usually an active material that is defluorinated during discharge. Examples of the positive electrode active material include simple metals, alloys, metal oxides, and fluorides thereof. Examples of the metal elements contained in the positive electrode active material include Cu, Ag, Ni, Co, Pb, Ce, Mn, Au, Pt, Rh, V, Os, Ru, Fe, Cr, Bi, Nb, Sb, Ti, Sn, and Zn. Among them, the positive electrode active material is preferably FeF3, CuF2, BiF3, or AgF.

[0037] From the viewpoint of capacity, the content of the positive electrode active material in the positive electrode active material layer is preferably as large as possible. The ratio of the mass of the positive electrode active material to the mass of the positive electrode active material layer may be 10 to 90 mass%, and preferably 20 to 80 mass%.

[0038] As the solid electrolyte, the solid electrolyte described above in "<Solid Electrolyte>" may be used.

[0039] The conductive assistant is not particularly limited as long as it has the desired electronic conductivity, and examples of the conductive assistant include carbon materials, such as carbon blacks such as acetylene black, ketjen black, furnace black, and thermal black, and carbon nanotubes.

[0040] The ratio of the mass of the conductive assistant to the mass of the positive active material electrode layer may be 1 to 70 mass %, and is preferably 5 to 40 mass %.

[0041] There are no particular limitations on the binder as long as it is chemically and electrically stable, and examples of the binder include fluorine-based binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE).

[0042] The thickness of the positive electrode layer varies greatly depending on the configuration of the battery, and is not particularly limited.

[0043] (electrolyte layer) When the fluoride ion battery of the present disclosure is a liquid-based battery, the electrolyte layer can be composed of, for example, an electrolyte solution and an optional separator.

[0044] The electrolyte may contain, for example, a fluoride salt and an organic solvent. Examples of the fluoride salt include inorganic fluoride salts, organic fluoride salts, and ionic liquids. An example of the inorganic fluoride salt is XF (X is Li, Na, K, Rb, or Cs). An example of the cation of the organic fluoride salt is an alkyl ammonium cation such as a tetramethylammonium cation. The concentration of the fluoride salt in the electrolyte is, for example, 0.1 mol% or more and 40 mol% or less, and preferably 1 mol% or more and 10 mol% or less.

[0045] The organic solvent of the electrolyte is usually a solvent that dissolves a fluoride salt. Examples of the organic solvent include glymes such as triethylene glycol dimethyl ether (G3) and tetraethylene glycol dimethyl ether (G4), cyclic carbonates such as ethylene carbonate (EC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), propylene carbonate (PC), and butylene carbonate (BC), and chain carbonates such as dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC). In addition, an ionic liquid may be used as the organic solvent.

[0046] The separator is not particularly limited as long as it has a composition that can withstand the range of use of fluoride ion batteries. Examples of the separator include polymer nonwoven fabrics such as polypropylene nonwoven fabrics and polyphenylene sulfide nonwoven fabrics, and microporous fillers of olefin resins such as polyethylene and polypropylene.

[0047] When the fluoride ion battery of the present disclosure is a solid-state battery, the electrolyte layer may be, for example, a layer of solid electrolyte.

[0048] As the solid electrolyte, the solid electrolyte described above in "<Solid Electrolyte>" may be used.

[0049] (Negative electrode active material layer) The negative electrode active material layer in the present disclosure contains a negative electrode active material, and optionally a solid electrolyte, a conductive additive, and a binder.

[0050] The negative electrode active material layer contains at least the above-mentioned La as the negative electrode active material. x C (1.00-x) Contains:

[0051] From the viewpoint of capacity, the content of the negative electrode active material in the negative active material electrode layer is preferably as high as possible. The ratio of the mass of the negative electrode active material to the mass of the negative electrode active material layer may be 10 to 90 mass%, and preferably 20 to 80 mass%.

[0052] For the solid electrolyte, conductive assistant, and binder, those similar to the descriptions in the above “(positive electrode active material layer)” may be adopted.

[0053] (Negative electrode current collector layer) Examples of the material of the negative electrode current collector layer include stainless steel (SUS), copper, nickel, iron, titanium, platinum, and carbon. Examples of the shape of the negative electrode current collector layer include foil shape, mesh shape, and porous shape.

[0054] (Battery case) The battery case may have any shape capable of accommodating the members of the fluoride ion battery, and a battery case used for a general battery can be adopted.

[0055] 《Manufacturing method of fluoride ion battery》 The manufacturing method of the fluoride ion battery of the present disclosure includes discharging a fluoride ion battery precursor having La as a negative electrode active material x C (1.00-x) until the upper limit potential of the negative electrode becomes 2.5 V to 3.5 V vs Pb / PbF2.

[0056] La as a negative electrode active material x C (1.00-x) itself can achieve a high charge-discharge capacity. However, by discharging a fluoride ion battery precursor having La x C (1.00-x) until the upper limit potential of the negative electrode becomes 2.5 V to 3.5 V vs Pb / PbF2, the charge-discharge capacity can be further improved.

[0057] When the potential of the negative electrode is discharged to a high potential of 2.5 V to 3.5 V vs Pb / PbF2, the crystal structure of La x C (1.00-x) changes and becomes at least partially amorphous, or the particles of La x C (1.00-x) are broken and micronized, whereby Lax C (1.00-x) It is believed that the reactivity of the fluorine ions with the fluorine ions is improved.

[0058] In addition, the La x C (1.00-x) may be synthesized, for example, by an arc melting method using La and C as raw materials, and optionally pulverized before use.

[0059] The upper limit potential of the negative electrode in discharging the fluoride ion battery precursor may be 2.5 V vs Pb / PbF2 or more, 2.6 V vs Pb / PbF2 or more, 2.7 V vs Pb / PbF2 or more, or 2.8 V vs Pb / PbF2 or more, and may be 3.5 V vs Pb / PbF2 or less, 3.4 V vs Pb / PbF2 or less, 3.3 V vs Pb / PbF2 or less, or 3.2 V vs Pb / PbF2 or less.

[0060] In the manufacturing method of the fluoride ion battery of the present disclosure, it is preferable to include charging and discharging so that the upper limit potential of the negative electrode is -0.5 V to 0.5 V vs. Pb / PbF2 and the lower limit potential of the negative electrode is -3.0 V to -2.0 V vs. Pb / PbF2, before discharging until the upper limit potential of the negative electrode is 2.5 V to 3.5 V vs. Pb / PbF2.

[0061] The upper limit potential of the negative electrode in charging and discharging before discharging until the upper limit potential of the negative electrode becomes 2.5V to 3.5V vs Pb / PbF2 may be -0.5V vs Pb / PbF2 or more, -0.4V vs Pb / PbF2 or more, -0.3V vs Pb / PbF2 or more, or -0.2V vs Pb / PbF2 or more, and may be 0.5V vs Pb / PbF2 or less, 0.4V vs Pb / PbF2 or less, 0.3V vs Pb / PbF2 or less, or 0.0V vs Pb / PbF2 or less.

[0062] In addition, the lower limit potential of the negative electrode in charging and discharging before discharging until the upper limit potential of the negative electrode becomes 2.5V to 3.5V vs Pb / PbF2 may be -3.0V vs Pb / PbF2 or more, -2.9V vs Pb / PbF2 or more, -2.7V vs Pb / PbF2 or more, or -2.5V vs Pb / PbF2 or more, and may be -2.0V vs Pb / PbF2 or less, -2.2V vs Pb / PbF2 or less, -2.3V vs Pb / PbF2 or less, or -2.4V vs Pb / PbF2 or less. EXAMPLES

[0063] Examples 1 and 2 and Reference Example 1 Example 1 La and C were weighed out so that the molar ratio of La:C was 0.33:0.67, and La was dissolved by an arc melting method to obtain a negative electrode active material. 0.33 C 0.67 was synthesized.

[0064] Next, CaF2 and BaF2 were mixed in a ball mill at 600 rpm for 20 hours to obtain CaF2 as a solid electrolyte. 0.5 Ba 0.5 F2 was synthesized.

[0065] Next, the synthesized La 0.33 C 0.67 The powder was crushed in a mortar to a size of 100 μm or less. 0.33 C 0.67 and Ca 0.5 Ba 0.5 F2 and vapor grown carbon fiber (VGCF) as a conductive additive were mixed in a ball mill at 200 rpm for 10 hours so that the weight ratio was 3:6:1, to prepare a negative electrode mixture.

[0066] The positive electrode mixture was prepared by weighing out PbF2 as a positive electrode active material and acetylene black as a conductive additive in a weight ratio of 95:5 and mixing them in a ball mill at 600 rpm for 3 hours.

[0067] The fluoride ion battery of Example 1 was prepared by laminating, in this order, Pt foil as the negative electrode current collector layer, the above-mentioned negative electrode composite as the negative electrode active material layer, the above-mentioned solid electrolyte as the solid electrolyte layer, the above-mentioned positive electrode composite as the positive electrode active material layer, and Pt foil as the positive electrode current collector layer.

[0068] Example 2 A fluoride ion battery of Example 2 was produced in the same manner as in Example 1, except that La and C were weighed out to have a molar ratio of La:C=0.40:0.60. That is, the negative electrode active material used in the fluoride ion battery of Example 2 was La 0.40 C 0.60 It is.

[0069] <Reference example 1> A fluoride ion battery of Reference Example 1 was produced in the same manner as in Example 1, except that La was used as the negative electrode active material.

[0070] <Charge / Discharge Test> The fluoride ion batteries of Examples 1 and 2 and Reference Example 1 were charged and discharged at a constant current of 50 μA and 200° C. for three cycles so that the upper limit potential of the negative electrode was 0.00 V vs. Pb / PbF2 and the lower limit potential of the negative electrode was −2.5 V vs. Pb / PbF2.

[0071] The charge / discharge curves of the fluoride ion batteries of each example are shown in Figures 2 to 4. Figure 2 is a graph showing the charge / discharge characteristics of the fluoride ion battery of Example 1. Figure 3 is a graph showing the charge / discharge characteristics of the fluoride ion battery of Example 2. Figure 4 is a graph showing the charge / discharge characteristics of the fluoride ion battery of Reference Example 1.

[0072] As shown in Figs. 2 to 4, La was used as the negative electrode active material. 0.33 C 0.67 The fluoride ion battery of Example 1 using La as the negative electrode active material 0.40 C 0.60 The fluoride ion battery of Example 2 using La had a higher charge / discharge capacity than the fluoride ion battery of Reference Example 1 using La as the negative electrode active material.

[0073] Examples 3 and 4 <Charge / discharge process> The fluoride ion battery of Example 1 after the charge / discharge test was charged until the upper limit potential of the negative electrode reached 3.00 V vs. Pb / PbF2, to obtain a fluoride ion battery of Example 3.

[0074] Similarly, the fluoride ion battery of Example 2 after the charge / discharge test was charged until the upper limit potential of the negative electrode reached 3.00 V vs. Pb / PbF2, to obtain a fluoride ion battery of Example 4.

[0075] <Charge / Discharge Test> The fluoride ion batteries of Examples 3 and 4 were subjected to the above-mentioned charge / discharge test.

[0076] The charge / discharge curves of the fluoride ion battery of Example 3 are shown in Fig. 5. The charge / discharge curves of the fluoride ion battery of Example 4 are shown in Fig. 6.

[0077] As shown in FIGS. 5 and 6, the fluoride ion batteries of Examples 3 and 4 in which charging was performed until the upper limit potential of the negative electrode reached 3.00 V vs Pb / PbF2 had a charge / discharge capacity of 300 mAh / g or more, and had a higher charge / discharge capacity than the fluoride ion batteries of Examples 1 and 2 in which charging was not performed until the upper limit potential of the negative electrode reached 3.00 V vs Pb / PbF2. [Explanation of symbols]

[0078] 1. Fluoride-ion battery 10 Positive electrode current collector layer 20 Cathode active material layer 30 Electrolyte layer 40 Negative electrode active material layer 50 Negative electrode current collector layer

Claims

1. La as a negative electrode active material ｘ C （１．００－ｘ） and 0.00<x<1.

00.

2. 2. The fluoride ion battery of claim 1, wherein 0.30≦x≦0.

45.

3. 3. The fluoride ion battery according to claim 1 or 2, comprising a lanthanide fluoride as a solid electrolyte.

4. 3. The fluoride ion battery according to claim 1 or 2, having a charge / discharge capacity of 300 mAh / g or more.

5. La as a negative electrode active material ｘ C （１．００－ｘ） and 0.00<x<1.00, the upper limit potential of the negative electrode is 2.5 to 3.5 V vs. Pb / PbF ２ and discharging the battery until

6. The upper limit potential of the negative electrode is 2.5V to 3.5V vs. Pb / PbF ２ Before the discharge is performed until the upper limit potential of the negative electrode reaches −0.5 V to 0.5 V vs. Pb / PbF ２ , and the lower limit potential of the negative electrode is −3.0V to −2.0V vs. Pb / PbF ２ The method for producing the fluoride ion battery according to claim 5, comprising charging and discharging the battery so that:

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