Solid electrolyte and lithium ion battery

Abstract

The solid electrolyte contains Li and M (wherein M is a metal element or a semimetal element other than Li). ) and F as the main phase, and in an X-ray diffraction pattern obtained by X-ray diffraction measurement, the content of the monoclinic phase as determined by the RIR method is 65% or more. As a result, it is possible to provide a solid electrolyte having high safety and high lithium ion conductivity.

Description

Technical Field

[0001] The invention relates to a solid electrolyte and a lithium ion battery. Background Art

[0002] In recent years, the development of solid electrolytes for all-solid batteries and the like is underway. For example, Japanese Patent Publication No. 2011-129312 (Document 1) discloses a solid electrolyte formed of a sulfide and an all-solid battery comprising the solid electrolyte. On the other hand, a solid electrolyte formed of a sulfide sometimes reacts with moisture in the atmosphere to generate toxic hydrogen sulfide gas. Therefore, International Publication No. 2021 / 161604 (Document 2) and International Publication No. 2021 / 186833 (Document 3) propose a solid electrolyte formed of a fluorine compound. Specifically, the solid electrolyte of Document 2 contains Li, Zr, Al and F. The solid electrolyte of Document 3 contains Li, Ti, Al, M and F, and M is Zr or Mg.

[0003] It should be noted that "Theoretical Design of Lithium Chloride Superionic Conductors for All-Solid-State High-Voltage Lithium-Ion Batteries" (ACS Appl. Mater. Interfaces, 2020, Vol. 12, pp. 34806-34814) (Document 4) by Dongsu Park et al. states that: 3 MCl 6 In the monoclinic (monoclinic) structure of MgO, the energy barrier for lithium ions to move is low.

[0004] However, although the solid electrolytes of Documents 2 and 3 formed of fluorine compounds have improved safety, their lithium ion conductivity is only 10 －6 S / cm is about insufficient. Summary of the invention

[0005] The present invention relates to a solid electrolyte, and an object of the present invention is to provide a solid electrolyte having high safety and high lithium ion conductivity.

[0006] The invention of Scheme 1 is a solid electrolyte comprising a monoclinic phase of a compound containing Li, M (wherein M is a metal element or a semimetal element other than Li) and F as a main phase, wherein in the X-ray diffraction pattern obtained by X-ray diffraction measurement, the content of the monoclinic phase quantified by the RIR method is greater than 65%.

[0007] According to the present invention, a solid electrolyte having high safety and high lithium ion conductivity can be provided.

[0008] The invention according to claim 2 is the solid electrolyte according to claim 1, wherein the compound further contains X which is at least one element selected from the group consisting of Cl, Br, and I.

[0009] The invention of Scheme 3 is based on the solid electrolyte of Scheme 2, and M includes Ga.

[0010] The invention of Scheme 4 is based on the solid electrolyte of Scheme 2 or 3, wherein the composition formula of the compound is Li 3 MF 6－ a X a Indicates that 0<a<6 is satisfied.

[0011] The invention of scheme 5 is based on the solid electrolyte of scheme 2 or 3, M includes Mα in the form of a trivalent cation and Mβ in the form of a tetravalent cation, and the composition formula of the compound is Li 3－b Mα 1－b Mβ b F 6－a X a It means that 0<a<6 and 0<b<1 are satisfied.

[0012] The invention according to claim 6 is based on any one of the solid electrolytes according to claims 1 to 5, wherein M includes Zr.

[0013] The invention of claim 7 is a lithium ion battery comprising the solid electrolyte of any one of claims 1 to 6.

[0014] The above-mentioned object and other objects, features, aspects and advantages will become more apparent from the following detailed description of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a longitudinal cross-sectional view showing an all-solid lithium ion secondary battery.

[0016] Figure 2 It is a figure which shows the X-ray diffraction pattern of the solid electrolyte powder. DETAILED DESCRIPTION

[0017] Figure 1 1 is a longitudinal cross-sectional view showing an all-solid lithium ion secondary battery 1 (hereinafter referred to as "all-solid secondary battery 1"). Figure 1 The positive electrode 11, the electrolyte layer 13 and the negative electrode 12 are sequentially provided above the positive electrode 11 and the negative electrode 12. That is, the electrolyte layer 13 is provided between the positive electrode 11 and the negative electrode 12. The electrolyte layer 13 is a solid electrolyte layer and also serves as a separator layer. The positive electrode 11 includes a current collector 111 and a positive electrode layer 112. The positive electrode layer 112 contains a positive electrode active material. The negative electrode 12 includes a current collector 121 and a negative electrode layer 122. The negative electrode layer 122 contains a negative electrode active material.

[0018] The positive electrode active material of the positive electrode layer 112 preferably includes a lithium composite oxide. A preferred positive electrode active material is a lithium composite oxide having a layered rock salt structure, such as NCM (Li(Ni, Co, Mn)O 2 The positive electrode active material may also be other lithium composite oxides, for example, NCA (Li(Ni, Co, Al)O 2 )、LCO(LiCoO 2 ), LNMO (LiNi 0.5 Mn 1.5 O 4 ), LFP (LiFePO 4 ) etc. The positive electrode layer 112 contains a solid electrolyte and an electron conduction aid (carbon black, etc.) described later in addition to the positive electrode active material. The positive electrode layer 112 in this embodiment is obtained by integrating these materials by pressurization and heating.

[0019] Examples of the negative electrode active material of the negative electrode layer 122 include LTO (Li 4 Ti 5 O 12 )、NTO(Nb 2 TiO 7 ), TiO 2 (titanium oxide), graphite, SiO (silicon monoxide) and other compounds. In addition to the negative electrode active material, the negative electrode layer 122 also includes a solid electrolyte described later. The negative electrode layer 122 may further include an electron conduction aid (carbon black, etc.). The negative electrode layer 122 in this embodiment is obtained by integrating these substances by pressurization and heating.

[0020] The configuration and material of the positive electrode 11 and the negative electrode 12 of the all-solid secondary battery 1 are not limited to the configuration and material described above, and other various configurations and materials may be adopted.

[0021] The electrolyte layer 13 is composed of the solid electrolyte involved in the present invention (hereinafter also referred to as "the present solid electrolyte"), or contains the solid electrolyte. The solid electrolyte is a lithium (Li) ion conductive material. The solid electrolyte contains: lithium element (Li), an element (M) that is a metal element or a semi-metal element other than Li, and a fluorine element (F). M can be only one element, or it can include more than two elements. An example of M is an element that is a trivalent cation. M preferably includes gallium (Ga), or it can be only Ga. Regarding M, other elements that are trivalent cations can also be included together with Ga, an example of which is aluminum (Al). Typically, the solid electrolyte does not contain sulfide and does not produce hydrogen sulfide gas. Therefore, a highly safe all-solid secondary battery 1 can be provided.

[0022] In this specification, the semimetal elements are boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), and tellurium (Te). The metal elements are elements included in Groups 1 to 12 of the periodic table except hydrogen and elements included in Groups 13 to 16 except the semimetals, C, N, P, O, S, and Se. That is, the metal elements are an element group that can be a cation when forming an inorganic compound with a halogen compound.

[0023] The present solid electrolyte contains a monoclinic (monoclinic) phase of a compound containing Li, M and F as a main phase. In addition, in the X-ray diffraction pattern obtained by X-ray diffraction (XRD) measurement of the solid electrolyte, the content of the monoclinic phase measured by the RIR method is 65% or more. As described later, in such a solid electrolyte, a 1×10 －5 The high lithium ion conductivity of S / cm or more is described below in detail with respect to the X-ray diffraction pattern.

[0024] The above compound preferably further contains X as at least one element selected from the group consisting of chlorine (Cl), bromine (Br) and iodine (I). X more preferably includes Cl, but may be Cl alone. Typically, X is an element that replaces a portion of F in the above compound. For example, the amount of X in the compound is less than the amount of F, but may be greater than the amount of F.

[0025] In the preferred solid electrolyte, the composition formula of the above compound is

[0026] Li 3 MF 6－a X a ···(1)

[0027] Indicates that 0<a<6 is satisfied. In the composition formula (1), 0.05<a<2 is more preferably satisfied, and 0.05<a<1.5 is further preferably satisfied. a may be 1 or less. Here, M is an element that is a trivalent cation, and may include two or more elements (for example, Ga and Al).

[0028] In another preferred solid electrolyte, the above-mentioned M includes Mα in the form of a trivalent cation and Mβ in the form of a tetravalent cation. In this case, the composition formula of the above-mentioned compound is

[0029] Li 3－b Mα 1－b Mβ b F 6－a X a ···(2)

[0030] Indicates that 0<a<6 and 0<b<1 are satisfied. In composition formula (2), similarly, it is more preferred to satisfy 0.05<a<2, and it is further preferred that 0.05<a<1.5. a may also be 1 or less. In one example of the solid electrolyte, Mα is Ga, and Mβ is zirconium (Zr). For example, the amount of Mα in the compound is greater than or equal to the amount of Mβ, but it may also be less than the amount of Mβ.

[0031] In confirming whether an unknown solid electrolyte is of composition formula (1) or (2), for example, Li, Ga, Al, and Zr can be quantified by ICP-emission spectrometry. For example, F and Cl can be quantified by ion chromatography. In the case where the solid electrolyte contains elements other than those mentioned above, a measurement method capable of quantifying the element is appropriately selected.

[0032] The molar ratio of Li, M, F and X in the above composition formula (1) is Li:M:F:X=3:1:6-a:a. In the molar ratio obtained by analyzing the unknown solid electrolyte, if the value of Li is greater than 0.90×3 and less than 1.10×3, Li is considered to satisfy the above composition formula (1). The value of Li is more preferably greater than 0.95×3 and less than 1.05×3. The same applies to M, F and X. In addition, with respect to the above composition formula (2), similarly to the above composition formula (1), if the respective values ​​of the molar ratios of Li, Mα, Mβ, F and X obtained by analysis are within the range of ±10% (preferably ±5%) of the value of the above composition formula (2), the above composition formula (2) is considered to be satisfied.

[0033] The present solid electrolyte is manufactured, for example, by the following method. First, a powder of a fluoride containing Li and a powder of a fluoride containing M are prepared. The fluoride containing Li is, for example, LiF (lithium fluoride). When M is Ga, the fluoride containing Ga is, for example, GaF 3(Gallium fluoride). When M is Ga and Al, the fluoride containing Al is, for example, AlF 3 (aluminum fluoride). When M is Ga and Zr, the fluoride containing Zr is, for example, ZrF 4 (zirconium fluoride). These powders are weighed and mixed in a prescribed molar ratio. When the solid electrolyte also contains X, for example, a powder of a halide (LiX) containing Li is prepared and mixed with the above powder. Examples of the halide (LiX) containing Li are LiCl (lithium chloride), LiBr (lithium bromide), and LiI (lithium iodide). As a raw material, a halide containing M can also be used, such as GaCl 3 (Gallium chloride), ZrCl 4 (zirconium chloride) may be a bromide containing M or an iodide containing M.

[0034] Next, the mixture is subjected to mechanical milling treatment (mechanical chemical milling). Here, in one example of mechanical milling treatment, a planetary ball mill is used. In the planetary ball mill, the tank body rotates and the worktable carrying the tank body revolves, so sometimes it generates very high impact energy. Mechanical milling treatment can also be performed using other types of pulverizers. Using the above-mentioned mechanical milling treatment, a powder of the present solid electrolyte for the positive electrode layer 112, the negative electrode layer 122 or the electrolyte layer 13 is obtained. In this treatment example, the mechanical milling treatment is performed at room temperature, but conditions such as temperature can be appropriately changed. The present solid electrolyte can also be manufactured using processes other than mechanical milling treatment, such as sintering.

[0035] Next, the experimental examples of solid electrolytes are described. The following experiments were conducted in a glove box with an argon (Ar) atmosphere at a dew point below -60°C. The conditions and measurement results of Experimental Examples 1 to 9 are shown in Table 1. Experimental Examples 2 to 9 are embodiments of the present invention in which the content of the monoclinic phase measured by the RIR method is 65% or more, and Experimental Example 1 is a comparative example in which the content of the monoclinic phase is less than 65%. The composition formula column in Table 1 also shows the composition formula of the solid electrolyte replaced by Li 3－b Ga 1－b Zr b F 6－a Cl a (In Experimental Examples 7 to 9, Al is also contained) The values ​​of a and b when expressed.

[0036] [Table 1]

[0037]

[0038] (Experimental Example 1)

[0039] As raw materials, commercially available LiF powder and commercially available GaF 3These powders are LiF:GaF 3 The two components were weighed so as to have a molar ratio of 3:1, and mechanical milling was performed using a planetary ball mill to obtain a solid electrolyte powder.

[0040] (Experimental Example 2)

[0041] In addition to LiF powder and GaF 3 In addition to the powder, commercially available LiCl powder was prepared according to the formula of LiF:LiCl:GaF 3 The same treatment as in Experimental Example 1 was carried out except that the weights were weighed so as to have a molar ratio of 2.9:0.1:1, thereby obtaining a solid electrolyte powder.

[0042] (Experimental Example 3)

[0043] Using LiF powder, LiCl powder and GaF 3 Powder, LiF:LiCl:GaF 3 The same treatment as in Experimental Example 1 was carried out except that the weights were weighed so as to have a molar ratio of 2.7:0.3:1, thereby obtaining a solid electrolyte powder.

[0044] (Experimental Example 4)

[0045] Using LiF powder, LiCl powder and GaF 3 Powder, LiF:LiCl:GaF 3 The same treatment as in Experimental Example 1 was carried out except that the weights were weighed so as to have a molar ratio of 2.4:0.6:1, thereby obtaining a solid electrolyte powder.

[0046] (Experimental Example 5)

[0047] Using LiF powder, LiCl powder and GaF 3 Powder, LiF:LiCl:GaF 3 The same treatment as in Experimental Example 1 was carried out except that the weights were weighed so as to have a molar ratio of 2:1:1, thereby obtaining a solid electrolyte powder.

[0048] (Experimental Example 6)

[0049] In addition to LiF powder, LiCl powder and GaF 3 In addition to powder, commercially available ZrF 4 Powder, LiF:LiCl:GaF 3 :ZrF 4 The same treatment as in Experimental Example 1 was carried out except that the weights were weighed so as to have a molar ratio of 2.2:0.6:0.8:0.2, thereby obtaining a solid electrolyte powder.

[0050] (Experimental Example 7)

[0051] In addition to LiF powder, LiCl powder and GaF 3 In addition to powder, commercially available AlF 3 Powder, LiF:LiCl:GaF 3 :AlF 3 The same treatment as in Experimental Example 1 was carried out except that the weights were weighed so as to have a molar ratio of 2.4:0.6:0.8:0.2, thereby obtaining a solid electrolyte powder.

[0052] (Experimental Example 8)

[0053] Using LiF powder, LiCl powder, GaF 3 Powder and AlF 3 Powder, LiF:LiCl:GaF 3 :AlF 3 The same treatment as in Experimental Example 1 was carried out except that the weights were weighed so as to have a molar ratio of 2.4:0.6:0.5:0.5, thereby obtaining a solid electrolyte powder.

[0054] (Experimental Example 9)

[0055] Using LiF powder, LiCl powder, GaF 3 Powder and AlF 3 Powder, LiF:LiCl:GaF 3 :AlF 3 The same treatment as in Experimental Example 1 was carried out except that the weights were weighed so as to have a molar ratio of 2.4:0.6:0.3:0.7, thereby obtaining a solid electrolyte powder.

[0056] <Measurement of lithium ion conductivity>

[0057] Solid electrolyte powder was placed in a mold consisting of a resin sleeve and metal upper and lower punches, and uniaxial pressing was performed at a pressure of 150 MPa. Lead wires were connected to the upper and lower punches, and impedance was measured at room temperature to calculate the lithium ion conductivity. In Table 1, the lithium ion conductivity is shown in the conductivity column.

[0058] <X-ray diffraction measurement>

[0059] For the powder obtained by adding and mixing the solid electrolyte powder and the Si powder as the internal standard sample, an X-ray diffraction pattern is obtained using an X-ray diffraction (XRD) device to identify the crystalline phase. The measurement conditions are set to: CuKα, 40kV, 40mA, and a sealed tube X-ray diffraction device (D8-ADVANCE manufactured by Bruker AXS Co., Ltd.) is used. The step size of the measurement is set to 0.02°. In the following description, the XRD analysis software "JADE" (MDI Company) is used for profile fitting to calculate the area intensity of each peak in the X-ray diffraction pattern. In addition, the XRD analysis software "EVA" (manufactured by Bruker AXS Co., Ltd.) is used to calculate the content of the monoclinic phase in the X-ray diffraction pattern using the RIR method (reference intensity ratio method).

[0060] Figure 2 : is a figure which shows the X-ray diffraction pattern of the solid electrolyte powder of Experimental Examples 1, 3 and 4. Figure 2 The top, second and third parts of the graph show the X-ray diffraction patterns of the solid electrolyte powders of Experimental Examples 1, 3 and 4, respectively. The fourth part is the card number 087-0588 (Li 3 GaF 6 The peaks shown are monoclinic phases, the lowest part of which is the peak with card number 020-0421 (Li 3 GaF 6 The unknown phase is a phase whose structure has not been determined. It should be noted that the peaks recorded as "Si" in the top part, the second part, and the third part are peaks derived from Si powder as an internal standard sample.

[0061] The X-ray diffraction patterns of the solid electrolyte powders of Experimental Examples 1 to 9 include peaks detected at substantially the same positions (diffraction angles 2θ) as the peaks shown in Card Numbers 087-0588. Thus, it was confirmed that the solid electrolyte powder of Experimental Example 1 contained Li 3 GaF 6 The solid electrolyte powders of Experimental Examples 2 to 5 contain Li 3 GaF 6 The monoclinic phase of the compound obtained by replacing part of F in the solid electrolyte powder with Cl. 3 GaF 6 The monoclinic phase of the compound in which part of Ga is replaced by Zr and part of F is replaced by Cl. In addition, it was confirmed that the solid electrolyte powders of Experimental Examples 7 to 9 contain Li 3 GaF6 The monoclinic phase of the compound in which part of Ga is replaced by Al and part of F is replaced by Cl. It should be noted that when M is an element other than Ga, the card information of the monoclinic phase of the compound containing the element, Li and F can be appropriately used.

[0062] In addition, each solid electrolyte powder contains the monoclinic phase of the above-mentioned compound as the main phase. Here, in the range of diffraction angle 2θ of 10 to 50° in the X-ray diffraction pattern, when the sum of the area intensities of all peaks belonging to the monoclinic phase of the above-mentioned compound (compound containing Li, M and F) is greater than the sum of the area intensities of all remaining peaks not belonging to the monoclinic phase, the monoclinic phase of the compound is assumed to be the main phase. In the solid electrolytes of Experimental Examples 1 to 9, the peaks belonging to the monoclinic phase of the compound are in the same range as Card No. 087-0588 (Li 3 GaF 6 In other words, the peaks not attributable to the monoclinic phase are at positions different from those of the peaks shown in card numbers 087-0588.

[0063] Next, the content (mass %) of the monoclinic phase is calculated using the RIR method in the X-ray diffraction pattern of each solid electrolyte powder. In Experimental Examples 1 to 9, the monoclinic phase is the crystalline phase shown by card number 087-0588. In addition, the crystalline phase that does not belong to the monoclinic phase is the unknown phase shown by card number 020-0421. In the RIR method, the pattern obtained by dividing the intensity of each peak of the monoclinic phase shown by card number 087-0588 by the RIR value of the monoclinic phase and the pattern obtained by dividing the intensity of each peak of the unknown phase shown by card number 020-0421 by the RIR value of the unknown phase by Vm:Vu are synthesized and fitted (Fitting) with the measured X-ray diffraction pattern. The content of the monoclinic phase is solved using (Vm / (Vm+Vu)). The same is true for the case where the solid electrolyte powder also contains other crystalline phases. The RIR value is the reference intensity ratio (sometimes written as I / Ic). The value recorded in the ICDD card information is used to calculate the content. For example, in the case of card number 087-0588, the RIR value is 1.77. In Table 1, the X-ray diffraction column shows the value of the monoclinic phase content calculated using the RIR method.

[0064] <Evaluation of experimental examples>

[0065] Figure 2 In the example, the peak at the diffraction angle 2θ near 26° and the peak at the diffraction angle 2θ near 34° ( Figure 2 The peaks indicated by arrows A1 and A2 in FIG. 1 are peaks detected only with the unknown phase (refer to Figure 2The fourth part and the bottom part of Experimental Examples 1 to 9), the intensity of these peaks decreases in the order of Experimental Examples 1, 3, and 4. On the other hand, as shown in Table 1, the lithium ion conductivity increases in the order of Experimental Examples 1, 3, and 4. In this way, it can be seen that the decrease in the peak near 26° and the peak near 34° is correlated with the increase in lithium ion conductivity. In addition, in Experimental Examples 1 to 9, there is a correlation between the content of the monoclinic phase quantified by the RIR method and the lithium ion conductivity. In the above-mentioned experimental examples, the lithium ion conductivity of Experimental Examples 2 to 9 in which the content of the monoclinic phase is larger than the value of Experimental Example 1 is greater than that of Experimental Example 1.

[0066] As described above, the peaks near 26° and 34° are included in the Li for card numbers 020-0421. 3 GaF 6 The peaks characteristically detected by the unknown phase are not contained in the peaks of card number 087-0588 (Li 3 GaF 6 Therefore, it is believed that due to the reduction of the peak near 26° and the peak near 34°, the unknown phase as a crystal structure is reduced and the content rate of the monoclinic phase is increased.

[0067] Dongsu Park et al., “Theoretical Design of Lithium Chloride Superionic Conductors for All-Solid-State High-Voltage Lithium-Ion Batteries” (ACS Appl. Mater. Interfaces, 2020, Vol. 12, pp. 34806-34814) (reference 4) states: 3 MCl 6 In the monoclinic structure, the energy barrier for lithium ion migration is low. 3 MX 6 The monoclinic phase of the compound (M is a metal element or semimetal element other than Li, and X is a halogen element) has a crystal structure in which the Li path is easily connected. Based on this, it is speculated that in a solid electrolyte based on a fluorine compound, which generally has the problem of improving ion conductivity, a high ion conductivity can be obtained by using the RIR method to measure a monoclinic phase content of 65% or more, that is, a high monoclinic phase content.

[0068] As described above, the present solid electrolyte contains a monoclinic phase of a compound containing Li, M (wherein M is a metal element or a semimetal element other than Li) and F as the main phase. In addition, in the X-ray diffraction pattern obtained by X-ray diffraction measurement, the content of the monoclinic phase quantified by the RIR method is 65% or more. Thus, in the solid electrolyte, the unknown phases can be reduced, and a solid electrolyte with a high content of the monoclinic phase and high lithium ion conductivity can be provided. The content of the monoclinic phase is preferably 68% or more, and more preferably 70% or more. In addition, the solid electrolyte does not contain sulfide, and will not produce hydrogen sulfide gas, thereby improving safety.

[0069] In a preferred solid electrolyte, M includes Ga as in Experimental Examples 2 to 9. This can more reliably improve the lithium ion conductivity.

[0070] Preferably, the compound further contains X which is at least one element selected from the group consisting of Cl, Br and I. Thus, as in Experimental Examples 2 to 9, the content of the monoclinic phase can be more reliably increased, thereby ensuring high lithium ion conductivity.

[0071] In the preferred solid electrolyte, the composition formula of the compound is

[0072] Li 3 MF 6－a X a ···(1)

[0073] Indicates that 0<a<6 is satisfied. Thus, a solid electrolyte with high lithium ion conductivity can be well realized. More preferably, as in Experimental Examples 2 to 5, 7 to 9, 0.05<a<2 is satisfied. Thus, in a solid electrolyte containing a monoclinic phase as the main phase, the lithium ion conductivity can be more reliably improved. The lower limit of a is more preferably 0.1. In addition, the upper limit of a is more preferably 1.

[0074] In another preferred solid electrolyte, M includes Mα in the form of a trivalent cation and Mβ in the form of a tetravalent cation.

[0075] Li 3－b Mα 1－b Mβ b F 6－a X a ···(2)

[0076] This indicates that 0<a<6 and 0<b<1 are satisfied. Thus, as in Experimental Example 6, a solid electrolyte having high lithium ion conductivity can be well realized.

[0077] The present solid electrolyte and all-solid secondary battery 1 can be modified in various ways.

[0078] In the present solid electrolyte, the content of the monoclinic phase may be 65% or more, and X may not be contained. The compound contained in the solid electrolyte may be a compound represented by a composition formula other than the above-mentioned composition formulas (1) and (2).

[0079] The present solid electrolyte can be mixed with other substances (which may contain Li) and used as an electrolyte material. In this case, the present solid electrolyte is preferably the component with the largest mass ratio among the components contained in the electrolyte material, i.e., the main component. The mass ratio of the main component in the electrolyte material is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more.

[0080] The present solid electrolyte used in the all-solid secondary battery 1 does not necessarily need to be contained in all of the positive electrode 11, the negative electrode 12, and the electrolyte layer 13, and may be contained in at least one of the positive electrode 11, the negative electrode 12, and the electrolyte layer 13. In addition, the present solid electrolyte can also be used in batteries other than all-solid secondary batteries, and can also be used for purposes other than batteries.

[0081] The configurations in the above-described embodiment and each modified example may be appropriately combined unless they are mutually contradictory.

[0082] Although the invention has been described and illustrated in detail, the above description is illustrative and not restrictive, and therefore, it can be understood that numerous modifications and variations may be employed without departing from the scope of the invention.

[0083] Explanation of symbols

[0084] 1…All-solid lithium-ion secondary battery

[0085] 11… Positive electrode

[0086] 12…Negative electrode

[0087] 13…Electrolyte layer

Claims

1. A solid electrolyte, in, A monoclinic phase containing a compound containing Li, M and F as a main phase, wherein M is a metal element or a semi-metal element other than Li, In the X-ray diffraction pattern obtained by X-ray diffraction measurement, the content of the monoclinic phase measured by the RIR method was 65% or more.

2. The solid electrolyte according to claim 1, in, The compound further contains X which is at least one element selected from the group consisting of Cl, Br and I.

3. The solid electrolyte according to claim 2, in, M includes Ga.

4. The solid electrolyte according to claim 2, in, The composition formula of the compound is Li 3 MF 6－a X a express, Satisfies 0<a<6.

5. The solid electrolyte according to claim 2, in, M includes Mα in the form of a trivalent cation and Mβ in the form of a tetravalent cation. The composition formula of the compound is Li 3－b Mα 1－b Mβ b F 6－a X a express, Satisfies 0<a<6 and 0<b<1.

6. The solid electrolyte according to claim 5, in, M includes Zr. 7 . A lithium ion battery comprising the solid electrolyte according to claim 1 .

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