Sulfide solid electrolyte, method for producing sulfide solid electrolyte, and power storage element

Abstract

To provide a sulfide solid electrolyte that has high ionic conductivity, a method for manufacturing such a sulfide solid electrolyte, and a power storage element using such as sulfide solid electrolyte.SOLUTION: A sulfide solid electrolyte has a composition represented by the following formula 1, and in an X-ray diffraction diagram with a Cu-Kα ray, has crystalline phases having a diffraction peak at respective positions with diffraction angles 2θ of 19.80°±0.50°, 20.10°±0.50°, 26.60°±0.50°, and 29.30°±0.50°. Formula 1: LiuAvMwP2SyXz. A method for manufacturing a sulfide solid electrolyte includes processing a raw material composition having the composition represented by the formula 1 with a mechanochemical method, and heating the raw material composition processed with the mechanochemical method.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a sulfide solid electrolyte, a method for producing the sulfide solid electrolyte, and an energy storage element.

Background Art

[0002] Lithium-ion secondary batteries are widely used in electronic devices such as personal computers and communication terminals, and automobiles, etc., because of their high energy density. Generally, the above lithium-ion secondary battery has a pair of electrodes electrically isolated by a separator and a non-aqueous electrolyte interposed between the electrodes, and is configured to charge and discharge by transferring lithium ions between both electrodes. Further, as an energy storage element other than the lithium-ion secondary battery, capacitors such as lithium-ion capacitors are also widely spread.

[0003] In recent years, as a non-aqueous electrolyte, an energy storage element using a solid electrolyte such as a sulfide solid electrolyte has been proposed instead of a non-aqueous electrolyte solution in which an electrolyte salt is dissolved in a liquid such as an organic solvent. As one of the sulfide solid electrolytes, Patent Document 1 describes a sulfide solid electrolyte material containing M 1 element, M 2 element and S element, wherein the M 1 is at least one selected from the group consisting of Li, Na, K, Mg, Ca, Zn, and the M 2 is at least one selected from the group consisting of P, Sb, Si, Ge, Sn, B, Al, Ga, In, Ti, Zr, V, Nb, and having a peak at a position of 2θ = 29.58° ± 0.50° in X-ray diffraction measurement using CuKα rays. Such a solid electrolyte is known as an LGPS (Li 10 GeP 2 S 12 ) type sulfide solid electrolyte.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] From the viewpoint of increasing the output of energy storage elements and the like, the development of solid electrolytes having high ionic conductivity is desired.

[0006] The present invention has been made based on the above circumstances, and an object thereof is to provide a sulfide solid electrolyte having high ionic conductivity, a method for producing such a sulfide solid electrolyte, and an energy storage element using such a sulfide solid electrolyte.

Means for Solving the Problems

[0007] The sulfide solid electrolyte according to one aspect of the present invention has a composition represented by the following formula 1, and has a crystal phase having diffraction peaks at positions where the diffraction angle 2θ is 19.80° ± 0.50°, 20.10° ± 0.50°, 26.60° ± 0.50°, and 29.30° ± 0.50° in an X-ray diffraction pattern using CuKα rays. Li u A v M w P 2 S y X z ···1 In formula 1, A is at least one selected from the group consisting of Na and K. M is at least one selected from the group consisting of B, Al, Si, Ti, V, Cu, Zn, Ga, Ge, Zr, Nb, Mo, In, Sn, Sb, Hf, Ta, W, Tl, Pb, and Bi. X is at least one selected from the group consisting of O, F, Cl, Se, Br, and I. u, v, w, y, and z are numbers satisfying 6 ≦ u ≦ 14, 0 ≦ v ≦ 1, 0.8 ≦ w ≦ 2, 8 ≦ y ≦ 14, 0 < z ≦ 1, and (u + v) / w ≧ 8.0, respectively.

[0008] The manufacturing method of a sulfide solid electrolyte according to another aspect of the present invention includes treating a raw material composition having a composition represented by the following formula 1 by a mechanochemical method, and heating the raw material composition treated by the mechanochemical method. Li u A v M w P 2 S y X z ···1 In formula 1, A is at least one selected from the group consisting of Na and K. M is at least one selected from the group consisting of B, Al, Si, Ti, V, Cu, Zn, Ga, Ge, Zr, Nb, Mo, In, Sn, Sb, Hf, Ta, W, Tl, Pb, and Bi. X is at least one selected from the group consisting of O, F, Cl, Se, Br, and I. u, v, w, y, and z are numbers satisfying 6 ≦ u ≦ 14, 0 ≦ v ≦ 1, 0.8 ≦ w ≦ 2, 8 ≦ y ≦ 14, 0 < z ≦ 1, and (u + v) / w ≧ 8.0, respectively.

[0009] The power storage element according to another aspect of the present invention contains the sulfide solid electrolyte according to one aspect of the present invention.

Advantages of the Invention

[0010] According to one embodiment of the present invention, it is possible to provide a sulfide solid electrolyte having high ionic conductivity, a manufacturing method of such a sulfide solid electrolyte, and a power storage element using such a sulfide solid electrolyte.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0012] First, the sulfide solid electrolyte, the method for manufacturing the sulfide solid electrolyte, and the outline of the power storage element disclosed by this specification will be described.

[0013] The sulfide solid electrolyte according to one aspect of the present invention has a composition represented by the following formula 1 and has a crystal phase having diffraction peaks at positions where the diffraction angle 2θ is 19.80° ± 0.50°, 20.10° ± 0.50°, 26.60° ± 0.50°, and 29.30° ± 0.50° in an X-ray diffraction pattern using CuKα rays. Li u A v M w P 2 S y X z ···1 In formula 1, A is at least one selected from the group consisting of Na and K. M is at least one selected from the group consisting of B, Al, Si, Ti, V, Cu, Zn, Ga, Ge, Zr, Nb, Mo, In, Sn, Sb, Hf, Ta, W, Tl, Pb, and Bi. X is at least one selected from the group consisting of O, F, Cl, Se, Br, and I. u, v, w, y, and z are numbers satisfying 6 ≤ u ≤ 14, 0 ≤ v ≤ 1, 0.8 ≤ w ≤ 2, 8 ≤ y ≤ 14, 0 < z ≤ 1, and (u + v) / w ≥ 8.0, respectively.

[0014] The sulfide solid electrolyte has high ionic conductivity. The reason why the sulfide solid electrolyte exhibits such an effect is not clear, but the following reasons are speculated. The sulfide solid electrolyte is an LGPS-type sulfide solid electrolyte having a predetermined crystal structure, and a part of the sulfur element in the crystal structure is substituted with a predetermined element X (at least one selected from the group consisting of O, F, Cl, Se, Br, and I). It is speculated that the substitution with this element X weakens the Coulomb interaction between atoms in the crystal structure and improves the ionic conductivity. Further, in the sulfide solid electrolyte, (u + v) / w ≥ 8.0 is satisfied, the content ratio of elements (Li and A) that can be conducted as ions is high, w is 0.8 or more, and an element M (at least one selected from the group consisting of B, Al, Si, Ti, V, Cu, Zn, Ga, Ge, Zr, Nb, Mo, In, Sn, Sb, Hf, Ta, W, Tl, Pb, and Bi) necessary for forming the LGPS-type sulfide solid electrolyte is present in a sufficient content ratio. It is also speculated that this enhances the ionic conductivity.

[0015] The "X-ray diffraction pattern using CuKα radiation" is obtained by the following powder X-ray diffraction measurement. A sample holder for airtight X-ray diffraction measurement is filled with a sulfide solid electrolyte powder to be measured under an argon atmosphere with a dew point of -50°C or lower. Powder X-ray diffraction measurement is performed using an X-ray diffractometer ("MiniFlex II" manufactured by Rigaku). The radiation source is CuKα radiation, the tube voltage is 30 kV, the tube current is 15 mA, and the diffracted X-rays are detected by a high-speed one-dimensional detector (model number: D / teX Ultra 2) through a Kβ filter with a thickness of 30 μm. The sampling width is 0.01°, the scan speed is 5° / min, the divergence slit width is 0.625°, the receiving slit width is 13 mm (OPEN), and the scattering slit width is 8 mm.

[0016] It is preferable that the above M contains Sn and the above X contains at least one selected from the group consisting of Cl, Br, and I. In such a case, the ionic conductivity of the sulfide solid electrolyte is further increased.

[0017] The intensity I of the diffraction peak at the position where the diffraction angle 2θ is 29.30° ± 0.50° A to the intensity I of the diffraction peak at the position where the diffraction angle 2θ is 34.10° ± 0.50° B The ratio I B / I A is preferably less than 0.75. When the ratio I B / I A is less than 0.75, the ionic conductivity of the sulfide solid electrolyte is further increased. The diffraction peak at the position where the diffraction angle 2θ is 34.10° ± 0.50° tends to appear when the sulfide solid electrolyte is synthesized by a liquid phase method or the like and the elemental composition is not suitable. It is considered that the lower the amount of the crystal phase having such a diffraction peak, the higher the ionic conductivity.

[0018] A method for producing a sulfide solid electrolyte according to another aspect of the present invention includes treating a raw material composition having a composition represented by the following formula 1 by a mechanochemical method, and heating the raw material composition treated by the mechanochemical method. Li u A v M w P 2 S y X z ···1 In formula 1, A is at least one selected from the group consisting of Na and K. M is at least one selected from the group consisting of B, Al, Si, Ti, V, Cu, Zn, Ga, Ge, Zr, Nb, Mo, In, Sn, Sb, Hf, Ta, W, Tl, Pb, and Bi. X is at least one selected from the group consisting of O, F, Cl, Se, Br, and I. u, v, w, y, and z are numbers satisfying 6 ≤ u ≤ 14, 0 ≤ v ≤ 1, 0.8 ≤ w ≤ 2, 8 ≤ y ≤ 14, 0 < z ≤ 1, and (u + v) / w ≥ 8.0, respectively.

[0019] The method for producing the sulfide solid electrolyte can easily produce a sulfide solid electrolyte having high ionic conductivity.

[0020] An energy storage element according to another aspect of the present invention contains the sulfide solid electrolyte according to one aspect of the present invention.

[0021] Since the energy storage element uses a sulfide solid electrolyte with high ionic conductivity, good energy storage element performance is exhibited.

[0022] The sulfide solid electrolyte, the method for manufacturing the sulfide solid electrolyte, the energy storage element, the energy storage device, the method for manufacturing the non-aqueous electrolyte energy storage element, and other embodiments according to one embodiment of the present invention will be described in detail. Note that the names of the respective constituent members (each constituent element) used in each embodiment may be different from the names of the respective constituent members (each constituent element) used in the background art.

[0023] <Solid electrolyte> (Composition) The sulfide solid electrolyte according to one embodiment of the present invention has a composition represented by the following formula 1. Li u A v M w P 2 S y X z ···1 In formula 1, A is at least one selected from the group consisting of Na and K. M is at least one selected from the group consisting of B, Al, Si, Ti, V, Cu, Zn, Ga, Ge, Zr, Nb, Mo, In, Sn, Sb, Hf, Ta, W, Tl, Pb, and Bi. X is at least one selected from the group consisting of O, F, Cl, Se, Br, and I. u, v, w, y, and z are numbers that satisfy 6 ≦ u ≦ 14, 0 ≦ v ≦ 1, 0.8 ≦ w ≦ 2, 8 ≦ y ≦ 14, 0 < z ≦ 1, and (u + v) / w ≧ 8.0, respectively.

[0024] The above M is an element necessary to form an LGPS-type sulfide solid electrolyte together with Li, P, and S. As the above M, it is preferable to include at least one selected from the group consisting of Si, Ge, and Sn, which are Group 14 elements, and more preferably to include Sn. Further, the above M is preferably at least one selected from the group consisting of Si, Ge, and Sn, which are Group 14 elements, and more preferably Sn. In particular, sulfur atoms (sulfide ions: S 2-When a part of is replaced with an element X having a larger ionic radius (for example, Br, I), it is preferable that the above M contains Sn. Si 4+ or Ge 4+ Sn having a larger ionic radius than Si 4+ and Ge

[0025] By containing , a solid electrolyte with a new composition can be obtained while maintaining the crystal structure. The above X preferably contains at least one selected from the group consisting of F, Cl, Br, and I, more preferably contains at least one selected from the group consisting of Cl, Br, and I, and even more preferably contains at least one selected from the group consisting of Br and I. Further, the above X is preferably at least one selected from the group consisting of F, Cl, Br, and I, more preferably at least one selected from the group consisting of Cl, Br, and I, and even more preferably at least one selected from the group consisting of Br and I. When a part of the sulfur atoms (sulfide ions: S 2- ) in the crystal structure is replaced with a halogen that can exist as a monovalent anion with a lower valence, and further when it is replaced with Br (Br - ) or I (I - ) having an ionic radius larger than that of the sulfide ion, the ionic conduction path in the crystal structure expands, and the ionic conductivity increases because the Coulomb interaction between atoms is particularly sufficiently weakened.

[0026] The lower limit of the above u is preferably 7, more preferably 8, even more preferably 9.0, and even more preferably 9.5. By setting the above u to be equal to or higher than the lower limit, the lithium content ratio increases, and the ionic conductivity further increases. The upper limit of the above u is preferably 12, more preferably 11, and even more preferably 10.

[0027] The upper limit of the above v is preferably 0.2, more preferably 0.1, and even more preferably 0.01.

[0028] The lower limit of the above w is preferably 0.9, more preferably 0.95. The upper limit of the above w is preferably 1.5, more preferably 1.2, even more preferably 1.1, and still more preferably 1.05. By setting the above w to be equal to or less than the above upper limit, the ionic conductivity is further increased.

[0029] The lower limit of the above y is preferably 9, more preferably 10, and even more preferably 11. The upper limit of the above y is preferably 13, more preferably 12.

[0030] The lower limit of the above z is preferably 0.01, more preferably 0.03, even more preferably 0.05, and in some cases may be even more preferably 0.1, 0.15, 0.2 or 0.25. The upper limit of the above z is preferably 0.5, more preferably 0.4, and even more preferably 0.35.

[0031] By setting the above u, v, w, y and z to be equal to or greater than the above lower limit or equal to or less than the above upper limit, the ionic conductivity and the like tend to be further increased.

[0032] The lower limit of the above (u + v) / w is preferably 8.5, more preferably 9.0, and even more preferably 9.5. By setting the above (u + v) / w to be equal to or greater than the above lower limit, the ionic conductivity is further increased. The upper limit of the above (u + v) / w is preferably 15, more preferably 12, even more preferably 11, and still more preferably 10.

[0033] The lower limit of the above u / w is preferably 8.0, more preferably 8.5, even more preferably 9.0, and still more preferably 9.5. By setting the above u / w to be equal to or greater than the above lower limit, the conductivity of lithium ions is increased. The upper limit of the above u / w is preferably 15, more preferably 12, even more preferably 11, and still more preferably 10.

[0034] (Crystal structure) The sulfide solid electrolyte has a crystal phase having diffraction peaks at positions where the diffraction angle 2θ is 19.80° ± 0.50°, 20.10° ± 0.50°, 26.60° ± 0.50°, and 29.30° ± 0.50° in the X-ray diffraction pattern using CuKα radiation. These diffraction peaks are characteristic peaks of the LGPS type sulfide solid electrolyte. That is, the sulfide solid electrolyte is an LGPS type sulfide solid electrolyte.

[0035] In the sulfide solid electrolyte, the intensity I of the diffraction peak at the position where the diffraction angle 2θ is 29.30° ± 0.50° A with respect to the intensity I of the diffraction peak at the position where the diffraction angle 2θ is 34.10° ± 0.50° B of the ratio I B / I A is preferably less than 0.75, and more preferably less than 0.65. When the ratio I B / I A is less than 0.75, the ionic conductivity of the sulfide solid electrolyte is further increased. On the other hand, the lower limit of the ratio I B / I A may be 0 or may be 0.05.

[0036] (Physical properties, uses, etc.) As the lower limit of the ionic conductivity of the sulfide solid electrolyte at 25°C, 3.0 mS / cm is preferable, and 3.2 mS / cm is more preferable. When the ionic conductivity of the sulfide solid electrolyte at 25°C is equal to or higher than the above lower limit, the charge and discharge performance of the energy storage element can be improved. The upper limit of the ionic conductivity may be, for example, 10 mS / cm or may be 6 mS / cm.

[0037] The ionic conductivity of the sulfide solid electrolyte is determined by measuring the AC impedance by the following method. In an argon atmosphere with a dew point of -50°C or lower, 120 mg of sample powder is put into a powder molding machine with an inner diameter of 10 mm, and then uniaxially pressed and formed at 50 MPa or lower using a hydraulic press. After releasing the pressure, 120 mg of SUS316L powder is put on the upper surface of the sample as a current collector, and then uniaxially pressed and formed again at 50 MPa or lower using a hydraulic press. Next, 120 mg of SUS316L powder is put on the lower surface of the sample as a current collector, and a pellet for measuring ionic conductivity is obtained by uniaxially pressing and forming at 360 MPa for 5 minutes. This pellet for measuring ionic conductivity is inserted into an HS cell manufactured by Hokuden Co., Ltd., and AC impedance measurement is performed at a predetermined temperature. The measurement conditions are an applied voltage amplitude of 20 mV, a frequency range of 1 MHz to 100 mHz, and a measurement temperature of 25°C.

[0038] As the upper limit of the electronic conductivity of the sulfide solid electrolyte at 25°C, 1×10 -6 S / cm is preferable, 1×10 -7 S / cm is more preferable, 1×10 -8 S / cm is even more preferable. When the electronic conductivity of the sulfide solid electrolyte is below the above upper limit, the charge and discharge performance of the power storage element including the sulfide solid electrolyte can be further enhanced.

[0039] The shape of the sulfide solid electrolyte is not particularly limited, and is usually granular, massive, etc. The solid electrolyte can be suitably used as an electrolyte of a power storage element such as a lithium ion secondary battery, particularly a lithium ion power storage element. Among them, it can be particularly suitably used as an electrolyte of an all-solid-state battery. Incidentally, the solid electrolyte can be used for any of the positive electrode layer, the separator layer, the negative electrode layer, etc. in the power storage element.

[0040] <Manufacturing method of sulfide solid electrolyte> The method for producing a sulfide solid electrolyte according to an embodiment of the present invention is not particularly limited, but the following method is preferred. That is, the method for producing a solid electrolyte according to an embodiment of the present invention includes treating a raw material composition having a composition represented by the following formula 1 by a mechanochemical method (mechanochemical treatment step), and heating the raw material composition treated by the mechanochemical method (heating step). Li u A v M w P 2 S y X z ···1 In Formula 1, A is at least one selected from the group consisting of Na and K. M is at least one selected from the group consisting of B, Al, Si, Ti, V, Cu, Zn, Ga, Ge, Zr, Nb, Mo, In, Sn, Sb, Hf, Ta, W, Tl, Pb, and Bi. X is at least one selected from the group consisting of O, F, Cl, Se, Br, and I. u, v, w, y, and z are numbers satisfying 6 ≦ u ≦ 14, 0 ≦ v ≦ 1, 0.8 ≦ w ≦ 2, 8 ≦ y ≦ 14, 0 < z ≦ 1, and (u + v) / w ≧ 8.0, respectively.

[0041] Note that the "raw material composition" means a mixture obtained by mixing two or more compounds or simple substances used as raw materials (hereinafter, the compounds and simple substances are collectively referred to as compound equivalents). It is sufficient that the composition of the entire raw material composition, that is, the composition based on all the elements contained in the raw material composition, satisfies Formula 1.

[0042] (Mechanochemical treatment step) The raw material composition used in this project has the composition represented by the above formula (1). The raw material composition can include, for example, a compound containing lithium, a compound containing element A (at least one selected from the group consisting of Na and K), a compound containing element M (at least one selected from the group consisting of B, Al, Si, Ti, V, Cu, Zn, Ga, Ge, Zr, Nb, Mo, In, Sn, Sb, Hf, Ta, W, Tl, Pb, and Bi), a compound containing phosphorus, a compound containing sulfur, and a compound containing element X (at least one selected from the group consisting of O, F, Cl, Se, Br, and I), etc. The raw material composition may contain a compound containing two or more of lithium, element A, element M, phosphorus, sulfur, and element X.

[0043] Examples of the compound containing lithium include Li 2 S, Li 2 O, Li 2 CO 3 , lithium halides (LiBr, LiI, etc.), metallic lithium, etc. The compound containing lithium may be used alone or in combination of two or more.

[0044] Examples of the compound containing element A include sulfides, oxides, halides, carbonates, etc. of element A. The compound containing element A may be used alone or in combination of two or more.

[0045] Examples of the compound containing element M include sulfides, oxides, etc. of element M. For example, when element M is Sn, SnS 2 , SnO, SnO 2 , SnO 3 , etc. can be used, and SnS 2 is preferred. The compound containing element M may be used alone or in combination of two or more.

[0046] Examples of the compound containing phosphorus include P 2 S 3 , P 2 S 5 , P 2 O 5, examples include elemental phosphorus and the like. Compounds containing phosphorus and the like may be used alone or in combination of two or more.

[0047] Examples of compounds containing sulfur include, for example, Li 2 S, P 2 S 3 , P 2 S 5 , Al 2 S 3 , SiS 2 , SnS 2 , examples include elemental sulfur and the like. Compounds containing sulfur and the like may be used alone or in combination of two or more.

[0048] Examples of compounds containing element X include halides, oxides, or selenides of lithium, element A, element M, phosphorus, sulfur, and the like. Among these, lithium halides (LiBr, LiI, etc.) are preferred. Compounds containing element X may be used alone or in combination of two or more.

[0049] The specific content and preferred content of each element in the raw material composition are the same as those of each element in the sulfide solid electrolyte according to the above-described embodiment of the present invention.

[0050] In this step, the raw material composition is treated by the mechanochemical method. The mechanochemical method (also referred to as mechanochemical treatment, etc.) refers to a synthesis method using a mechanochemical reaction. The mechanochemical reaction refers to a chemical reaction such as an amorphization reaction, a crystallization reaction, a solid solution reaction, or a phase transition reaction that utilizes high energy locally generated by mechanical energy such as friction or compression during the crushing process of a solid substance.

[0051] Examples of devices for performing treatment by the mechanochemical method include grinding and dispersing machines such as ball mills, bead mills, vibration mills, turbo mills, mechanofusion, and disk mills. Among these, a ball mill is preferred. As the balls and mill containers used in the ball mill, those made of tungsten carbide (WC) or zirconium oxide (ZrO 2)Pre-made products and the like can be preferably used.

[0052] When processing by a ball mill, the mill rotation speed during processing can be, for example, 100 rpm or more and 1,000 rpm or less. Also, the processing time can be, for example, 0.1 hour or more and 100 hours or less.

[0053] From the viewpoint of preventing compositional deviation due to raw material volatilization in the heating process, the raw material composition processed by the mechanochemical method is preferably a sulfide glass having a certain degree of crystal structure of the raw material rather than a sulfide glass having no crystal structure of the raw material at all. By heating the raw material composition that has become a sulfide glass having a certain degree of crystal structure of the raw material, precipitation of impurity phases is less, and the target LGPS-type sulfide solid electrolyte can be obtained.

[0054] (Heating process) In this step, the raw material composition that has undergone the mechanochemical treatment step is heated. As a result, at least a part of the raw material composition is crystallized, and the target LGPS-type sulfide solid electrolyte is obtained. The temperature range of the above heating is preferably, for example, 300°C or more and 600°C or less, more preferably 325°C or more and 500°C or less, and even more preferably 350°C or more and 450°C or less. The heating time is preferably, for example, 1 hour or more and 24 hours or less, and more preferably 3 hours or more and 16 hours or less.

[0055] <Energy storage element> As an embodiment of the energy storage element of the present invention, a all-solid-state battery will be described below as a specific example. The energy storage element 10 shown in FIG. 1 is a all-solid-state battery, which is a secondary battery in which a positive electrode layer 1 and a negative electrode layer 2 are arranged via a separator layer 3. The positive electrode layer 1 has a positive electrode substrate 4 and a positive electrode active material layer 5, and the positive electrode substrate 4 is the outermost layer of the positive electrode layer 1. The negative electrode layer 2 has a negative electrode substrate 7 and a negative electrode active material layer 6, and the negative electrode substrate 7 is the outermost layer of the negative electrode layer 2. In the energy storage element 10 shown in FIG. 1, a negative electrode active material layer 6, a separator layer 3, a positive electrode active material layer 5, and a positive electrode substrate 4 are laminated in this order on the negative electrode substrate 7.

[0056] The storage element 10 contains a sulfide solid electrolyte according to an embodiment of the present invention in at least one of the positive electrode layer 1, the negative electrode layer 2, and the separator layer 3. More specifically, a sulfide solid electrolyte according to an embodiment of the present invention is contained in at least one of the positive electrode active material layer 5, the negative electrode active material layer 6, and the separator layer 3.

[0057] The storage element 10 may also be used in combination with other solid electrolytes other than the sulfide solid electrolyte according to an embodiment of the present invention. Examples of other solid electrolytes include sulfide solid electrolytes other than the sulfide solid electrolyte according to an embodiment of the present invention, oxide solid electrolytes, dry polymer electrolytes, gel polymer electrolytes, pseudo solid electrolytes, etc., and sulfide solid electrolytes are preferred. Also, a plurality of different types of solid electrolytes may be contained in one layer in the storage element 10, or different solid electrolytes may be contained for each layer.

[0058] Examples of sulfide solid electrolytes other than the sulfide solid electrolyte according to an embodiment of the present invention include, for example, Li 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 -Li 3 N、Li 2 S-SiS 2 、Li 2 S-SiS 2 -LiI、Li 2 S-SiS 2 -LiBr、Li 2 S-SiS2 - LiCl, Li 2 S - SiS 2 - B 2 S 3 - LiI, Li 2 S - SiS 2 - P 2 S 5 - LiI, Li 2 S - B 2 S 3 , Li 2 S - P 2 S 5 - Z m S 2n (However, m and n are positive numbers, and Z is any one of Ge, Zn, and Ga.), Li 2 S - GeS 2 , Li 2 S - SiS 2 - Li 3 PO 4 , Li 2 S - SiS 2 - Li x MO y (However, x and y are positive numbers, and M is any one of P, Si, Ge, B, Al, Ga, and In.), Li 10 GeP 2 S 12 etc. can be cited.

[0059] [Positive electrode layer] The positive electrode layer 1 has a positive electrode substrate 4 and a positive electrode active material layer 5 disposed directly or via an intermediate layer on the positive electrode substrate 4.

[0060] (Positive electrode substrate) The positive electrode substrate 4 has conductivity. Whether it has "conductivity" is determined by the volume resistivity measured in accordance with JIS - H - 0505 (1975) being 10 7It is determined using Ω·cm as the threshold value. As the material of the positive electrode substrate 4, metals such as aluminum, titanium, tantalum, and stainless steel, or alloys thereof are used. Among these, aluminum or an aluminum alloy is preferable from the viewpoints of corrosion resistance, high conductivity, and cost. Examples of the positive electrode substrate 4 include a foil, a vapor deposition film, a mesh, and a porous material, and a foil is preferable from the viewpoint of cost. Therefore, as the positive electrode substrate 4, an aluminum foil or an aluminum alloy foil is preferable. Examples of the aluminum or aluminum alloy include A1085, A3003, A1N30, etc. defined in JIS-H-4000 (2014) or JIS-H4160 (2006).

[0061] The average thickness of the positive electrode substrate 4 is preferably 3 μm or more and 50 μm or less, more preferably 5 μm or more and 40 μm or less, still more preferably 8 μm or more and 30 μm or less, and particularly preferably 10 μm or more and 25 μm or less. By setting the average thickness of the positive electrode substrate 4 within the above range, it is possible to increase the strength of the positive electrode substrate 4 and increase the energy density per unit volume of the energy storage element 10. The "average thickness" of the positive electrode substrate 4 and the negative electrode substrate 7 described later refers to the value obtained by dividing the mass of the substrate of a predetermined area by the true density and area of the substrate.

[0062] (Intermediate layer) The intermediate layer is a layer disposed between the positive electrode substrate 4 and the positive electrode active material layer 5. The intermediate layer contains a conductive agent such as carbon particles to reduce the contact resistance between the positive electrode substrate 4 and the positive electrode active material layer 5. The configuration of the intermediate layer is not particularly limited, and for example, it contains a binder and a conductive agent.

[0063] (Positive electrode active material layer) The positive electrode active material layer 5 contains a positive electrode active material. The positive electrode active material layer 5 can be formed from a so-called positive electrode mixture containing a positive electrode active material. The positive electrode active material layer 5 may contain a mixture or composite containing a positive electrode active material and a solid electrolyte or the like. The positive electrode active material layer 5 contains optional components such as a conductive agent, a binder (binding agent), a thickener, and a filler as necessary. One or more of these optional components may not be substantially contained in the positive electrode active material layer 5.

[0064] As the positive electrode active material contained in the positive electrode active material layer 5, it can be appropriately selected from known positive electrode active materials commonly used in lithium ion secondary batteries and all-solid-state batteries. As the positive electrode active material, a material that can usually occlude and release lithium ions is used. As the positive electrode active material, for example, α-NaFeO 2 Lithium transition metal composite oxides having a type crystal structure, lithium transition metal composite oxides having a spinel type crystal structure, polyanion compounds, chalcogen compounds, sulfur, etc. can be mentioned. As the lithium transition metal composite oxide having an α-NaFeO 2 type crystal structure, for example, Li[Li x Ni (1-x) O 2 (0 ≦ x < 0.5), Li[Li x Ni γ Co (1-x-γ) O 2 (0 ≦ x < 0.5, 0 < γ < 1), Li[Li x Co (1-x) O 2 (0 ≦ x < 0.5), Li[Li x Ni γ Mn (1-x-γ) O 2 (0 ≦ x < 0.5, 0 < γ < 1), Li[Li x Ni γ Mn β Co (1-x-γ-β) O 2 (0 ≦ x < 0.5, 0 < γ, 0 < β, 0.5 < γ + β < 1), Li[Li x Ni γ Co β Al (1-x-γ-β) O 2 (0 ≦ x < 0.5, 0 < γ, 0 < β, 0.5 < γ + β < 1), etc. can be mentioned. As the lithium transition metal composite oxide having a spinel type crystal structure, Li x Mn 2 O 4 , Li x Ni γ Mn (2-γ) O 4 etc. can be mentioned. As the polyanion compound, LiFePO 4 , LiMnPO 4 , LiNiPO 4 , LiCoPO 4, Li 3 V 2 (PO 4 ) 3 , Li 2 MnSiO 4 , Li 2 CoPO 4 F, etc. Examples of chalcogen compounds include titanium disulfide, molybdenum disulfide, molybdenum dioxide, etc. Atoms or polyanions in these materials may be partially substituted with atoms or anion species composed of other elements. The surfaces of these materials may be coated with other materials. In the positive electrode active material layer 5, one of these materials may be used alone, or two or more of them may be mixed and used.

[0065] The positive electrode active material is usually in the form of particles (powder). The average particle size of the positive electrode active material is preferably, for example, 0.1 μm or more and 20 μm or less. By setting the average particle size of the positive electrode active material to be not less than the above lower limit, the production or handling of the positive electrode active material becomes easy. By setting the average particle size of the positive electrode active material to be not more than the above upper limit, the electron conductivity of the positive electrode active material layer 5 is improved. When using a composite of the positive electrode active material and other materials, the average particle size of the composite is taken as the average particle size of the positive electrode active material. The "average particle size" means a value at which the volume-based cumulative distribution calculated in accordance with JIS-Z-8819-2 (2001) based on the particle size distribution measured by the laser diffraction / scattering method for a diluted solution in which particles are diluted with a solvent conforms to JIS-Z-8825 (2013) and is 50%.

[0066] To obtain powder with a predetermined particle size, a pulverizer, a classifier, etc. are used. Examples of pulverization methods include methods using a mortar, a ball mill, a sand mill, a vibration ball mill, a planetary ball mill, a jet mill, a counter jet mill, a swirling air flow type jet mill, or a sieve. During pulverization, wet pulverization with water or an organic solvent such as hexane coexisting can also be used. As classification methods, sieves, air classifiers, etc. are used as needed for both dry and wet processes.

[0067] As the content of the positive electrode active material in the positive electrode active material layer 5, it is preferably 10% by mass or more and 95% by mass or less, more preferably 30% by mass or more, and even more preferably 50% by mass or more. By setting the content of the positive electrode active material within the above range, the capacitance of the power storage element 10 can be increased.

[0068] When the positive electrode active material layer 5 contains a solid electrolyte, the content of the solid electrolyte is preferably 5% by mass or more and 90% by mass or less, more preferably 20% by mass or more and 70% by mass or less, and in some cases, even more preferably 50% by mass or less. By setting the content of the solid electrolyte within the above range, the capacitance of the power storage element 10 can be increased. When using the sulfide solid electrolyte according to an embodiment of the present invention for the positive electrode active material layer 5, the content of the sulfide solid electrolyte according to an embodiment of the present invention with respect to the total solid electrolyte in the positive electrode active material layer 5 is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and even more preferably substantially 100% by mass.

[0069] The above mixture of the positive electrode active material and the solid electrolyte, etc. is a mixture produced by mixing the positive electrode active material and the solid electrolyte, etc. by mechanical milling or the like. For example, the mixture of the positive electrode active material and the solid electrolyte, etc. can be obtained by mixing the particulate positive electrode active material and the particulate solid electrolyte, etc. Examples of the above composite of the positive electrode active material and the solid electrolyte, etc. include a composite having a chemical or physical bond between the positive electrode active material and the solid electrolyte, etc., and a composite obtained by mechanically composite the positive electrode active material and the solid electrolyte, etc. The above composite is one in which the positive electrode active material and the solid electrolyte, etc. are present within one particle. For example, those in which the positive electrode active material and the solid electrolyte, etc. form an aggregated state, and those in which a solid electrolyte-containing film is formed on at least a part of the surface of the positive electrode active material.

[0070] The conductive agent is not particularly limited as long as it is a material having conductivity. Examples of such conductive agents include carbonaceous materials, metals, conductive ceramics, and the like. Examples of carbonaceous materials include graphite, non-graphitic carbon, graphene-based carbon, and the like. Examples of non-graphitic carbon include carbon nanofibers, pitch-based carbon fibers, carbon black, and the like. Examples of carbon black include furnace black, acetylene black, ketjen black, and the like. Examples of graphene-based carbon include graphene, carbon nanotubes (CNTs), fullerenes, and the like. Examples of the shape of the conductive agent include powder form, fibrous form, and the like. As the conductive agent, one of these materials may be used alone, or two or more thereof may be mixed and used. Further, these materials may be used in a composite form. For example, a material in which carbon black and CNTs are combined may be used. Among these, carbon black is preferable from the viewpoints of electron conductivity and coatability, and among them, acetylene black is particularly preferable.

[0071] The content of the conductive agent in the positive electrode active material layer 5 is preferably 1% by mass or more and 10% by mass or less, and more preferably 3% by mass or more and 9% by mass or less. By setting the content of the conductive agent within the above range, the energy density of the power storage element 10 can be increased.

[0072] Examples of the binder include thermoplastic resins such as fluororesins (polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), etc.), polyethylene, polypropylene, polyacrylic, polyimide; elastomers such as ethylene-propylene-diene rubber (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber; polysaccharide polymers, and the like.

[0073] The content of the binder in the positive electrode active material layer 5 is preferably 1% by mass or more and 10% by mass or less, and more preferably 3% by mass or more and 9% by mass or less. By setting the content of the binder within the above range, the active material can be stably held.

[0074] Examples of the thickener include polysaccharide polymers such as carboxymethyl cellulose (CMC) and methyl cellulose. When the thickener has a functional group that reacts with lithium or the like, this functional group may be deactivated in advance by methylation or the like.

[0075] The filler is not particularly limited. Examples of the filler include polyolefins such as polypropylene and polyethylene, inorganic oxides such as silicon dioxide, alumina, titanium dioxide, calcium oxide, strontium oxide, barium oxide, and magnesium oxide, hydroxides such as magnesium hydroxide, calcium hydroxide, and aluminum hydroxide, carbonates such as calcium carbonate, sparingly soluble ionic crystals such as calcium fluoride, barium fluoride, and barium sulfate, nitrides such as aluminum nitride and silicon nitride, and mineral resource-derived substances such as talc, montmorillonite, boehmite, zeolite, apatite, kaolin, mullite, spinel, olivine, sericite, bentonite, and mica, or artificial products thereof.

[0076] The positive electrode active material layer 5 may contain typical non-metal elements such as B, N, P, F, Cl, Br, and I, typical metal elements such as Li, Na, Mg, Al, K, Ca, Zn, Ga, Ge, Sn, Sr, and Ba, and transition metal elements such as Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Zr, and Nb as components other than the positive electrode active material, solid electrolyte, conductive agent, binder, thickener, and filler.

[0077] The average thickness of the positive electrode active material layer 5 is preferably 30 μm or more and 1,000 μm or less, and more preferably 60 μm or more and 500 μm or less. By setting the average thickness of the positive electrode active material layer 5 to be equal to or greater than the above lower limit, a power storage element 10 having a high energy density can be obtained. By setting the average thickness of the positive electrode active material layer 5 to be equal to or less than the above upper limit, miniaturization of the power storage element 10 can be achieved. The average thickness of the positive electrode active material layer 5 is the average value of the thicknesses measured at any five locations. The same applies to the average thicknesses of the negative electrode active material layer 6 and the separator layer 3 described later.

[0078] [Negative electrode layer] The negative electrode layer 2 includes a negative electrode substrate 7 and a negative electrode active material layer 6 disposed directly or via an intermediate layer on the negative electrode substrate 7. The configuration of the intermediate layer is not particularly limited and can be selected, for example, from the configurations exemplified in the positive electrode layer 1.

[0079] (Negative electrode substrate) The negative electrode substrate 7 has conductivity. As the material of the negative electrode substrate 7, metals such as copper, nickel, stainless steel, nickel-plated steel, aluminum or alloys thereof, carbonaceous materials, etc. are used. Among these, copper or a copper alloy is preferable. Examples of the negative electrode substrate 7 include a foil, a vapor deposition film, a mesh, a porous material, etc., and a foil is preferable from the viewpoint of cost. Therefore, as the negative electrode substrate 7, a copper foil or a copper alloy foil is preferable. Examples of the copper foil include a rolled copper foil, an electrolytic copper foil, etc.

[0080] The average thickness of the negative electrode substrate 7 is preferably 2 μm or more and 35 μm or less, more preferably 3 μm or more and 30 μm or less, still more preferably 4 μm or more and 25 μm or less, and particularly preferably 5 μm or more and 20 μm or less. By setting the average thickness of the negative electrode substrate 7 within the above range, the strength of the negative electrode substrate 7 can be increased while increasing the energy density per volume of the power storage element 10.

[0081] (Negative electrode active material layer) The negative electrode active material layer 6 contains a negative electrode active material. The negative electrode active material layer 6 can be formed from a so-called negative electrode binder containing a negative electrode active material. The negative electrode active material layer 6 may contain a mixture or composite containing a negative electrode active material and a solid electrolyte, etc. The negative electrode active material layer 6 contains optional components such as a conductive agent, a binder, a thickener, a filler, etc. as required. The optional components such as a conductive agent, a binder, a thickener, a filler, etc. can be selected from the materials exemplified in the positive electrode active material layer 5. One or more of these optional components may not be substantially contained in the negative electrode active material layer 6.

[0082] The negative electrode active material layer 6 may contain, as components other than the negative electrode active material, solid electrolyte, conductive agent, binder, thickening agent, and filler, typical non-metal elements such as B, N, P, F, Cl, Br, and I, typical metal elements such as Li, Na, Mg, Al, K, Ca, Zn, Ga, Ge, Sn, Sr, and Ba, and transition metal elements such as Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Zr, Ta, Hf, and Nb.

[0083] As the negative electrode active material contained in the negative electrode active material layer 6, it can be appropriately selected from known negative electrode active materials commonly used in lithium-ion secondary batteries and all-solid-state batteries. As the negative electrode active material, a material that can usually occlude and release lithium ions is generally used. Examples of the negative electrode active material include metallic Li; metals or semi-metals such as Si and Sn; metal oxides or semi-metal oxides such as Si oxide, Ti oxide, and Sn oxide; Li 4 Ti 5 O 12 , LiTiO 2、 TiNb 2 O 7 and other titanium-containing oxides; polyphosphoric acid compounds; silicon carbide; carbon materials such as graphite (graphite) and non-graphitic carbon (easily graphitizable carbon or hardly graphitizable carbon). Among these materials, graphite and non-graphitic carbon are preferred. In the negative electrode active material layer 6, one of these materials may be used alone, or two or more of them may be mixed and used.

[0084] "Graphite" refers to a carbon material having an average lattice plane spacing (d 002 ) of the (002) plane determined by X-ray diffraction method of 0.33 nm or more and less than 0.34 nm before charge and discharge or in the discharged state. Examples of graphite include natural graphite and artificial graphite. From the viewpoint of obtaining a material with stable physical properties, artificial graphite is preferred.

[0085] "Non-graphitic carbon" refers to the average lattice plane spacing (d 002) refers to a carbon material having a d of 0.34 nm or more and 0.42 nm or less. Examples of non-graphitic carbon include non-graphitizable carbon and graphitizable carbon. Examples of non-graphitic carbon include, for example, resin-derived materials, petroleum pitch or petroleum pitch-derived materials, petroleum coke or petroleum coke-derived materials, plant-derived materials, alcohol-derived materials, and the like.

[0086] Here, the "discharged state" means a state in which lithium ions that can be occluded and released during charge and discharge are sufficiently released from the carbon material that is the negative electrode active material. For example, in a single electrode battery using a negative electrode containing a carbon material as the working electrode and metallic Li as the counter electrode, it is a state in which the open circuit voltage is 0.7 V or more.

[0087] "Non-graphitizable carbon" refers to a carbon material having a d 002 of 0.36 nm or more and 0.42 nm or less.

[0088] "Graphitizable carbon" refers to a carbon material having a d 002 of 0.34 nm or more and less than 0.36 nm.

[0089] The negative electrode active material is usually particles (powder). The average particle size of the negative electrode active material can be, for example, 1 nm or more and 100 μm or less. When the negative electrode active material is a carbon material, a titanium-containing oxide, or a polyphosphoric acid compound, the average particle size thereof may be 1 μm or more and 100 μm or less. When the negative electrode active material is Si, Sn, a Si oxide, or a Sn oxide, etc., the average particle size thereof may be 1 nm or more and 1 μm or less. By setting the average particle size of the negative electrode active material to be equal to or greater than the above lower limit, the production or handling of the negative electrode active material becomes easy. By setting the average particle size of the negative electrode active material to be equal to or less than the above upper limit, the electron conductivity of the negative electrode active material layer 6 is improved. To obtain powder having a predetermined particle size, a pulverizer, a classifier, or the like is used. The pulverization method and the classification method can be selected, for example, from the methods exemplified in the positive electrode active material layer 5. When the negative electrode active material is a metal such as metallic Li, the negative electrode active material may be in the form of a foil.

[0090] As the content of the negative electrode active material in the negative electrode active material layer 6, it is preferably 10% by mass or more and 95% by mass or less, more preferably 30% by mass or more, and even more preferably 50% by mass or more. By setting the content of the negative electrode active material within the above range, the capacitance of the power storage element 10 can be increased.

[0091] When the negative electrode active material layer 6 contains a solid electrolyte, the content of the solid electrolyte is preferably 5% by mass or more and 90% by mass or less, more preferably 20% by mass or more and 70% by mass or less, and in some cases, even more preferably 50% by mass or less. By setting the content of the solid electrolyte within the above range, the capacitance of the power storage element 10 can be increased. When using the sulfide solid electrolyte according to an embodiment of the present invention for the negative electrode active material layer 6, the content of the sulfide solid electrolyte according to an embodiment of the present invention with respect to the total solid electrolyte in the negative electrode active material layer 6 is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and even more preferably substantially 100% by mass.

[0092] The mixture or composite of the above negative electrode active material and solid electrolyte, etc. can be obtained by replacing the positive electrode active material with the negative electrode active material in the mixture or composite of the positive electrode active material and solid electrolyte, etc. described above.

[0093] The average thickness of the negative electrode active material layer 6 is preferably 30 μm or more and 1,000 μm or less, more preferably 60 μm or more and 500 μm or less. By setting the average thickness of the negative electrode active material layer 6 to be equal to or greater than the above lower limit, a power storage element 10 having a high energy density can be obtained. By setting the average thickness of the negative electrode active material layer 6 to be equal to or less than the above upper limit, miniaturization of the power storage element 10 can be achieved.

[0094] [Separator layer] The separator layer 3 contains a solid electrolyte. As the solid electrolyte contained in the separator layer 3, various solid electrolytes can be used in addition to the sulfide solid electrolyte according to one embodiment of the present invention described above. Among them, it is preferable to use a sulfide solid electrolyte. As the content of the solid electrolyte in the separator layer 3, 70% by mass or more is preferable, 90% by mass or more is more preferable, 99% by mass or more is further preferable, and in some cases, it is even more preferable to be substantially 100% by mass. Further, when using the sulfide solid electrolyte according to one embodiment of the present invention for the separator layer 3, the content of the sulfide solid electrolyte according to one embodiment of the present invention in all the solid electrolytes in the separator layer 3 is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 90% by mass or more, and even more preferably substantially 100% by mass.

[0095] The separator layer 3 may contain oxides such as Li 3 PO 4 and optional components such as halogen compounds, binders, thickeners, and fillers. The optional components such as binders, thickeners, and fillers can be selected from the materials exemplified in the positive electrode active material layer 5.

[0096] As the average thickness of the separator layer 3, 1 μm or more and 50 μm or less is preferable, and 3 μm or more and 20 μm or less is more preferable. By setting the average thickness of the separator layer 3 to be equal to or greater than the above lower limit, it becomes possible to reliably insulate the positive electrode layer 1 and the negative electrode layer 2. By setting the average thickness of the separator layer 3 to be equal to or less than the above upper limit, it becomes possible to increase the energy density of the power storage element 10.

[0097] The power storage element of the present embodiment can be mounted as a power storage unit (battery module) configured by aggregating a plurality of power storage elements in a power source for automobiles such as electric vehicles (EVs), hybrid vehicles (HEVs), plug-in hybrid vehicles (PHEVs), a power source for electronic devices such as personal computers and communication terminals, or a power source for power storage. In this case, the technology of the present invention may be applied to at least one power storage element included in the power storage unit.

[0098] FIG. 2 shows an example of a power storage device 30 formed by further aggregating power storage units 20 in which two or more electrically connected power storage elements 10 are aggregated. The power storage device 30 may include a bus bar (not shown) that electrically connects two or more power storage elements 10, a bus bar (not shown) that electrically connects two or more power storage units 20, and the like. The power storage unit 20 or the power storage device 30 may include a state monitoring device (not shown) that monitors the state of one or more power storage elements.

[0099] <Method for manufacturing a power storage element> The method for manufacturing a power storage element according to an embodiment of the present invention can be carried out by a generally known method, except that a sulfide solid electrolyte according to an embodiment of the present invention is used as at least a part of a solid electrolyte in the production of at least one of a positive electrode layer, a separator layer, and a negative electrode layer. Specifically, the manufacturing method includes, for example, (1) preparing a positive electrode mixture, (2) preparing a material for the separator layer, (3) preparing a negative electrode mixture, and (4) laminating the positive electrode layer, the separator layer, and the negative electrode layer. Hereinafter, each step will be described in detail.

[0100] (1) Positive electrode mixture preparation step In this step, a positive electrode mixture for forming a positive electrode layer (positive electrode active material layer) is usually produced. The method for producing the positive electrode mixture is not particularly limited and can be appropriately selected according to the purpose. For example, mechanical milling of the material of the positive electrode mixture, pressure molding of the positive electrode active material, sputtering using a target material of the positive electrode active material, and the like can be mentioned. When the positive electrode mixture contains a mixture or composite including a positive electrode active material and a solid electrolyte, etc., this step may include, for example, mixing the positive electrode active material and the solid electrolyte, etc. using a mechanical milling method or the like to produce a mixture or composite of the positive electrode active material and the solid electrolyte, etc.

[0101] (2) Separator layer material preparation step In this process, generally, a material for the isolation layer is produced to form the isolation layer. When the energy storage element is a lithium-ion energy storage element, the material for the isolation layer can be a solid electrolyte. The solid electrolyte as the material for the isolation layer can be produced by a conventionally known method. For example, it can be obtained by treating a predetermined material by the mechanical milling method. The material for the isolation layer may also be produced by heating a predetermined material above the melting temperature by the melt quenching method, melt-mixing it at a predetermined ratio, and then quenching. Other methods for synthesizing the material for the isolation layer include, for example, the solid-phase method of firing under reduced pressure encapsulation, the liquid-phase method such as dissolution precipitation, the vapor-phase method (PLD), and firing in an argon atmosphere after mechanical milling.

[0102] (3) Preparation process of negative electrode binder In this process, generally, a negative electrode binder for forming a negative electrode layer (negative electrode active material layer) is produced. The specific production method of the negative electrode binder is the same as that of the positive electrode binder. When the negative electrode binder contains a mixture or composite containing a negative electrode active material and a solid electrolyte, etc., this process may include, for example, mixing the negative electrode active material and the solid electrolyte, etc. using the mechanical milling method, etc., to produce a mixture or composite of the negative electrode active material and the solid electrolyte, etc.

[0103] (4) Lamination process In this process, for example, a positive electrode layer having a positive electrode substrate and a positive electrode active material layer, an isolation layer, and a negative electrode layer having a negative electrode substrate and a negative electrode active material layer are laminated to form a laminate. In this process, the positive electrode layer, the isolation layer, and the negative electrode layer may be sequentially formed in this order, or vice versa, and the order of formation of each layer is not particularly limited. The above positive electrode layer is formed, for example, by pressure molding a positive electrode substrate and a positive electrode binder, the above isolation layer is formed by pressure molding a material for the isolation layer, and the above negative electrode layer is formed by pressure molding a negative electrode substrate and a negative electrode binder. The positive electrode layer, the isolation layer, and the negative electrode layer may be laminated by pressure molding the positive electrode substrate, the positive electrode binder, the isolation layer material, the negative electrode binder, and the negative electrode substrate at once. The positive electrode layer and the negative electrode layer may be pre-formed respectively, and then pressure molded and laminated with the isolation layer.

[0104] <Other embodiments> Furthermore, the energy storage element of the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the gist of the present invention. For example, the configuration of one embodiment can be added to the configuration of another embodiment, and a part of the configuration of one embodiment can be replaced with the configuration of another embodiment or a well-known technique. Furthermore, a part of the configuration of one embodiment can be deleted. Also, a well-known technique can be added to the configuration of one embodiment.

[0105] In the above embodiment, the case where the energy storage element is used as an all-solid battery capable of charge and discharge has been described. However, the type, shape, dimensions, capacity, etc. of the energy storage element are arbitrary. The present invention can also be applied to various secondary batteries, electric double layer capacitors, or capacitors such as lithium ion capacitors.

[0106] The energy storage element according to the present invention may include other layers other than the positive electrode layer, the isolation layer, and the negative electrode layer. Also, the energy storage element according to the present invention may contain a liquid. Examples of such an energy storage element include an energy storage element in which an ionic liquid or the like is filled in voids such as the positive electrode active material layer 5, the isolation layer 3, and the negative electrode active material layer 6 in the above-described energy storage element 10. The sulfide solid electrolyte according to the present invention may be manufactured by a method other than the above-described method, for example, a liquid phase method or the like.

[0107] <Example> Hereinafter, the present invention will be described more specifically by way of examples. However, the present invention is not limited to the following examples.

[0108] [Example 1] By the following process, a sulfide solid electrolyte represented by the composition formula Li 9.95 Sn 1.00 P 2 S 11.95 I 0.05 was synthesized. In a glove box with an argon atmosphere having a dew point of -50°C or lower, Li 2 S (manufactured by Mitsuwa Chemical Co., Ltd.), P 2 S 5 (manufactured by Aldrich), SnS2 (High-purity chemical product) and LiI (manufactured by Aldrich) were weighed so that the composition of the raw material composition composed of these compounds was Li 9.95 Sn 1.00 P 2 S 11.95 I 0.05 and mixed in an agate mortar for 10 minutes. Specifically, Li 2 S, P 2 S 5 , SnS 2 and LiI were weighed at a molar ratio of 4.95:1:1:0.05. The total mass of the weighed compounds, that is, the mass of the raw material composition, was set to 1.5 g. This raw material composition was put into a sealed 80 mL zirconia pot containing 160 g of zirconia balls with a diameter of 4 mm, and treated by mechanochemical method at a revolution speed of 370 rpm for 20 hours using a planetary ball mill (manufactured by FRITSCH, model number Premium line P-7). Then, after heating to 400 °C at a heating rate of 2 °C / min, heating was performed at 400 °C for 8 hours to obtain the sulfide solid electrolyte of Example 1.

[0109] [Examples 2 to 5, Comparative Examples 1, 3 to 6] Except that the mixing ratio of each compound used in the raw material composition was adjusted so that the composition of the obtained sulfide solid electrolyte was as shown in Table 1, and the heating temperature was as shown in Table 1, the same procedure as in Example 1 was carried out to obtain the sulfide solid electrolytes of Examples 2 to 5 and Comparative Examples 1, 3 to 6. In Examples 4 and 5 and Comparative Examples 3 and 6, LiBr (manufactured by Aldrich) was used instead of LiI, and in Comparative Example 1, neither LiI nor LiBr was used.

[0110] [Comparative Example 2] By the following treatment, a sulfide solid electrolyte represented by the composition formula Li 8.65 Sn 1.09 P 2 S 11.36 Br 0.29 was synthesized. In a glove box with an argon atmosphere having a dew point of -50 °C or lower, Li 2 S (1.0 mole part) and P 2 S 5(0.5 mol portion) and were dissolved in acetonitrile as a solvent and stirred at room temperature for 12 hours. Next, P 2 S 5 (0.5 mol portion) was added and stirred at room temperature for 12 hours. At this time, the total concentration of the solutes (Li 2 S and P 2 S 5 ) was adjusted to 10% by mass. Next, LiBr (0.29 mol portion) and SnS 2 (1.09 mol portion) were added to the above solution and stirred at room temperature for 12 hours. Next, Li 2 S (3.18 mol portion) was added to the above solution and stirred at room temperature for 24 hours. Then, the above solution was vacuum dried at 200 °C for 3 hours to remove the solvent. The obtained raw material composition was heated to 475 °C at a heating rate of 2 °C / min and then heated at 475 °C for 8 hours to obtain the sulfide solid electrolyte of Comparative Example 2.

[0111] [Evaluation] (1) Powder X-ray diffraction measurement Powder X-ray diffraction measurements were performed on the sulfide solid electrolytes of Examples 1 to 5 and Comparative Examples 1 to 6. For the airtight X-ray diffraction measurement sample holder, the product name "General-purpose atmosphere separator" manufactured by Rigaku was used. Fig. 3 shows the X-ray diffraction patterns of the sulfide solid electrolytes of Examples 1 to 5. Fig. 4 shows the X-ray diffraction patterns of the sulfide solid electrolytes of Comparative Examples 1 to 6. In the sulfide solid electrolytes of Examples 1 to 5 and Comparative Examples 1, 2, 4 to 6, diffraction peaks appeared at the positions of diffraction angles 2θ of 19.80° ± 0.50°, 20.10° ± 0.50°, 26.60° ± 0.50°, and 29.30° ± 0.50° respectively, and it was confirmed that an LGPS-type sulfide solid electrolyte was obtained. On the other hand, in the sulfide solid electrolyte of Comparative Example 3, diffraction peaks did not appear at the positions of 19.80° ± 0.50°, 20.10° ± 0.50°, 26.60° ± 0.50°, and 29.30° ± 0.50°, and an LGPS-type sulfide solid electrolyte was not obtained. The intensity I of the diffraction peak at the position of diffraction angle 2θ of 29.30° ± 0.50° in the X-ray diffraction patterns of the sulfide solid electrolytes of Examples 1 to 5 and Comparative Examples 1, 2, 4 to 6 AThe intensity I of the diffraction peak at the position where the diffraction angle 2θ with respect to [object] is 34.10° ± 0.50° B of the ratio I B / I A is shown in Table 1.

[0112] (2) Ionic conductivity The ionic conductivity (σ 25 ) at 25°C of each sulfide solid electrolyte of Examples 1 to 5 and Comparative Examples 1 to 6 was measured and obtained by the above-described method using "VMP-300" manufactured by Bio-Logic. The measurement results are shown in Table 1.

[0113]

Table 1

[0114] As shown in Table 1, each of the sulfide solid electrolytes of Examples 1 to 5 has an ionic conductivity of 3.0 mS / cm or more, and it can be confirmed that they have high ionic conductivity.

Industrial Applicability

[0115] The solid electrolyte according to the present invention is suitably used as a solid electrolyte of a power storage element such as an all-solid-state battery.

Explanation of Signs

[0116] 1 Positive electrode layer 2 Negative electrode layer 3 Separation layer 4 Positive electrode substrate 5 Positive electrode active material layer 6 Negative electrode active material layer 7 Negative electrode substrate 10 Power storage element (all-solid-state battery) 20 Power storage unit 30 Power storage device

Claims

1. having a composition represented by the following formula (1), a sulfide solid electrolyte having a crystal phase having diffraction peaks at positions where diffraction angle 2θ is 19.80° ± 0.50°, 20.10° ± 0.50°, 26.60° ± 0.50°, and 29.30° ± 0.50° in an X-ray diffraction pattern using CuKα rays. Li ｕ A ｖ M ｗ P ２ S ｙ X ｚ ...1 In formula (1), A is at least one selected from the group consisting of Na and K. M is at least one selected from the group consisting of B, Al, Si, Ti, V, Cu, Zn, Ga, Ge, Zr, Nb, Mo, In, Sn, Sb, Hf, Ta, W, Tl, Pb, and Bi. X is at least one selected from the group consisting of F, Cl, Br, and I, and includes at least one selected from the group consisting of Br and I. u, v, w, y, and z are numbers satisfying 6 ≤ u ≤ 14, 0 ≤ v ≤ 1, 0.8 ≤ w ≤ 2, 8 ≤ y ≤ 14, 0 < z ≤ 1, and 9.0 ≤ (u + v) / w ≤ 10, respectively.

2. having a composition represented by the following formula (1), a sulfide solid electrolyte having a crystal phase having diffraction peaks at positions where diffraction angle 2θ is 19.80° ± 0.50°, 20.10° ± 0.50°, 26.60° ± 0.50°, and 29.30° ± 0.50° in an X-ray diffraction pattern using CuKα rays. Li ｕ A ｖ M ｗ P ２ S ｙ X ｚ ...1 In formula (1), A is at least one selected from the group consisting of Na and K. M is at least one selected from the group consisting of B, Al, Ti, V, Cu, Zn, Ga, Ge, Zr, Nb, Mo, In, Sn, Sb, Hf, Ta, W, Tl, Pb, and Bi. X is at least one selected from the group consisting of F, Cl, Br, and I, and includes at least one selected from the group consisting of Br and I. u, v, w, y, and z are numbers satisfying 6 ≤ u ≤ 14, 0 ≤ v ≤ 1, 0.8 ≤ w ≤ 2, 8 ≤ y ≤ 14, 0 < z ≤ 1, and (u + v) / w ≥ 9.0, respectively.

3. having a composition represented by the following formula (1), a sulfide solid electrolyte having a crystal phase having diffraction peaks at positions where diffraction angle 2θ is 19.80° ± 0.50°, 20.10° ± 0.50°, 26.60° ± 0.50°, and 29.30° ± 0.50° in an X-ray diffraction pattern using CuKα rays. Li ｕ A ｖ M ｗ P ２ S ｙ X ｚ ...1 In Formula 1, A is at least one selected from the group consisting of Na and K. M is at least one selected from the group consisting of B, Al, Si, Ti, V, Cu, Zn, Ga, Ge, Zr, Nb, Mo, In, Sn, Sb, Hf, Ta, W, Tl, Pb, and Bi and contains Sn. X is at least one selected from the group consisting of F, Cl, Br, and I and contains at least one selected from the group consisting of Br and I. u, v, w, y, and z are numbers that satisfy 6 ≤ u ≤ 14, 0 ≤ v ≤ 1, 0.8 ≤ w ≤ 2, 8 ≤ y ≤ 14, 0 < z ≤ 1, and (u + v) / w ≥ 9.0, respectively.

4. having a composition represented by the following Formula 1 A sulfide solid electrolyte having a crystal phase with diffraction peaks at positions where the diffraction angle 2θ is 19.80° ± 0.50°, 20.10° ± 0.50°, 26.60° ± 0.50°, and 29.30° ± 0.50° in an X-ray diffraction pattern using CuKα radiation (provided that the composition formula: Li ｘ Si ｙ P ｚ S ａ Ha ｗ (wherein Ha contains any one or more of Br, Cl, I, and F; 2.4 < (x - y) / (y + z) < 3.3), excluding a crystalline solid electrolyte characterized in that the sulfur content is 55 to 73% by mass, the silicon content is 2 to 11% by mass, and the content of the Ha element is 0.02% by mass or more).). Li ｕ A ｖ M ｗ P ２ S ｙ X ｚ ...1 In Formula 1, A is at least one selected from the group consisting of Na and K. M is at least one selected from the group consisting of B, Al, Si, Ti, V, Cu, Zn, Ga, Ge, Zr, Nb, Mo, In, Sn, Sb, Hf, Ta, W, Tl, Pb, and Bi. X is at least one selected from the group consisting of F, Cl, Br, and I and contains at least one selected from the group consisting of Br and I. u, v, w, y, and z are numbers that satisfy 6 ≤ u ≤ 14, 0 ≤ v ≤ 1, 0.8 ≤ w ≤ 2, 8 ≤ y ≤ 14, 0 < z ≤ 1, and (u + v) / w ≥ 9.0, respectively.

5. The sulfide solid electrolyte according to claim 1, claim 2, or claim 4, wherein M contains Sn.

6. The intensity I of the diffraction peak at the position where the diffraction angle 2θ is 29.30° ± 0.50° Ａ to the intensity I of the diffraction peak at the position where the diffraction angle 2θ is 34.10° ± 0.50° Ｂ of the ratio I Ｂ / I Ａ is less than 0.

75. The sulfide solid electrolyte according to any one of claims 1 to 5

7. processing a raw material composition having a composition represented by the following Formula 1 by a mechanochemical method, and heating the raw material composition processed by the mechanochemical method A method for producing a sulfide solid electrolyte, comprising: Li ｕ A ｖ M ｗ P ２ S ｙ X ｚ ...1 In Formula 1, A is at least one selected from the group consisting of Na and K. M is at least one selected from the group consisting of B, Al, Si, Ti, V, Cu, Zn, Ga, Ge, Zr, Nb, Mo, In, Sn, Sb, Hf, Ta, W, Tl, Pb, and Bi. X is at least one selected from the group consisting of F, Cl, Br, and I and contains at least one selected from the group consisting of Br and I. u, v, w, y, and z are numbers that satisfy 6 ≤ u ≤ 14, 0 ≤ v ≤ 1, 0.8 ≤ w ≤ 2, 8 ≤ y ≤ 14, 0 < z ≤ 1, and 9.0 ≤ (u + v) / w ≤ 10, respectively.

8. processing a raw material composition having a composition represented by the following Formula 1 by a mechanochemical method, and heating the raw material composition treated by the above mechanochemical method A method for producing a sulfide solid electrolyte comprising: Li ｕ A ｖ M ｗ P ２ S ｙ X ｚ ...1 In Formula 1, A is at least one selected from the group consisting of Na and K. M is at least one selected from the group consisting of B, Al, Ti, V, Cu, Zn, Ga, Ge, Zr, Nb, Mo, In, Sn, Sb, Hf, Ta, W, Tl, Pb, and Bi. X is at least one selected from the group consisting of F, Cl, Br, and I, and includes at least one selected from the group consisting of Br and I. u, v, w, y, and z are numbers satisfying 6 ≦ u ≦ 14, 0 ≦ v ≦ 1, 0.8 ≦ w ≦ 2, 8 ≦ y ≦ 14, 0 < z ≦ 1, and (u + v) / w ≧ 9.0, respectively.

9. treating a raw material composition having a composition represented by the following Formula 1 by a mechanochemical method, and heating the raw material composition treated by the above mechanochemical method A method for producing a sulfide solid electrolyte comprising: Li ｕ A ｖ M ｗ P ２ S ｙ X ｚ ...1 In Formula 1, A is at least one selected from the group consisting of Na and K. M is at least one selected from the group consisting of B, Al, Si, Ti, V, Cu, Zn, Ga, Ge, Zr, Nb, Mo, In, Sn, Sb, Hf, Ta, W, Tl, Pb, and Bi and includes Sn. X is at least one selected from the group consisting of F, Cl, Br, and I, and includes at least one selected from the group consisting of Br and I. u, v, w, y, and z are numbers satisfying 6 ≦ u ≦ 14, 0 ≦ v ≦ 1, 0.8 ≦ w ≦ 2, 8 ≦ y ≦ 14, 0 < z ≦ 1, and (u + v) / w ≧ 9.0, respectively.

10. A raw material composition having a composition represented by the following formula 1 (however, the composition formula: Li ｘ Si ｙ P ｚ S ａ Ha ｗ (In the formula, Ha includes any one or more of Br, Cl, I, and F. 2.4 < (x - y) / (y + z) < 3.3), and excluding the case where the content of S is 55 to 73% by mass, the content of Si is 2 to 11% by mass, and the content of the Ha element is 0.02% by mass or more.) treating () by a mechanochemical method, and heating the raw material composition treated by the above mechanochemical method A method for producing a sulfide solid electrolyte comprising: Li ｕ A ｖ M ｗ P ２ S ｙ X ｚ ・・・1 In Formula 1, A is at least one selected from the group consisting of Na and K. M is at least one selected from the group consisting of B, Al, Si, Ti, V, Cu, Zn, Ga, Ge, Zr, Nb, Mo, In, Sn, Sb, Hf, Ta, W, Tl, Pb, and Bi. X is at least one selected from the group consisting of F, Cl, Br, and I, and includes at least one selected from the group consisting of Br and I. u, v, w, y, and z are numbers satisfying 6 ≦ u ≦ 14, 0 ≦ v ≦ 1, 0.8 ≦ w ≦ 2, 8 ≦ y ≦ 14, 0 < z ≦ 1, and (u + v) / w ≧ 9.0, respectively.

11. A power storage element containing a sulfide solid electrolyte according to any one of claims 1 to 6.

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