i
`
`Patentamt
`Eurspaisches
`European
`Patent Office
`Office européen |
`des brevets
`
`(1 9)
`
`(12)
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`(11)
`
`EP 3 496 202 A1
`
`EUROPEAN PATENT APPLICATION
`published in accordancewith Art. 153(4) EPC
`
`Int Cl.:
`(51)
`(43) Date of publication:
`12.06.2019 Bulletin 2019/24
`HO1M 10/0562 (2979.01)§=—HO1B 1/06 (2006.01)
`HO1M 4/13 (2970.91)
`HO1M 101052 (2010.91)
`HO1M 10/0585 (2070-01)
`
`(21) Application number: 17836689.4
`
`(22) Date offiling: 07.07.2017
`
`(86)
`
`International application number:
`PCT/JP2017/024934
`
`(84) Designated Contracting States:
`AL AT BE BG CH CY CZ DE DK EE ES FI FR GB
`GR HR HU IEISIT LILT LU LV MC MK MT NL NO
`PL PT RO RSSE SI SK SMTR
`
`Designated Extension States:
`BA ME
`
`Designated Validation States:
`MA MD
`
`(30) Priority: 04.08.2016 JP 2016153736
`08.06.2017 JP 2017113102
`
`(71) Applicant: Panasonic Intellectual Property
`Management Co., Ltd.
`Osaka-shi, Osaka 540-6207 (JP)
`
`(72) Inventors:
`* ASANO Tetsuya
`Osaka 540-6207 (JP)
`
`
`
`(87)
`
`International publication number:
`WO 2018/025582 (08.02.2018 Gazette 2018/06)
`
`SAKAIAkihiro
`
`Osaka 540-6207 (JP)
`OHUCHI Satoru
`
`Osaka 540-6207 (JP)
`SAKAIDA Masashi
`
`Osaka 540-6207 (JP)
`MIYAZAKI Akinobu
`
`Osaka 540-6207 (JP)
`HASEGAWAShinya
`Osaka 540-6207 (JP)
`
`Representative: Eisenfilhr Speiser
`Patentanwalte Rechtsanwalte PartGmbB
`Postfach 10 60 78
`
`28060 Bremen (DE)
`
`(54)
`
`SOLID ELECTROLYTE MATERIAL, AND CELL
`
`(57)
`In known technologies, it is desired to realize a solid electrolyte material having a high lithium ion conductivity.
`A solid electrolyte material according to an aspect of the present disclosure is represented by the following Com-
`positional Formula (1):
`
`Lig37¥7X6
`
`Formula (1)
`
`where, 0 < z < 2 is satisfied; and X represents Cl or Br.
`
`EP3496202A1
`
`Printed by Jouve, 75001 PARIS (FR)
`
`(Cont. next page)
`
`

`

`EP 3 496 202 A1
`
`FIG. 1
`
`

`

`EP 3 496 202 A1
`
`Description
`
`Technical Field
`
`[0001] The present disclosure relates to a solid electrolyte material and a battery.
`
`Background Art
`
`[0002]
`[0003]
`
`PTL 1 discloses an all-solid battery using a sulfide solid electrolyte.
`PTL 2 discloses an all-solid battery using a halide containing indium as a solid electrolyte.
`
`Citation List
`
`Patent Literature
`
`[0004]
`
`PTL 1: Japanese Unexamined Patent Application Publication No. 2011-129312
`PTL 2: Japanese Unexamined Patent Application Publication No. 2006-244734
`
`Summaryof Invention
`
`Technical Problem
`
`[0005]
`
`In knowntechnologies, it is desired to realize a solid electrolyte material having a high lithium ion conductivity.
`
`Solution to Problem
`
`10
`
`15
`
`20
`
`25
`
`[0006]Asolid electrolyte material according to an aspect of the present disclosure is represented by the following
`30
`Compositional Formula (1):
`
`Lig37¥7X6
`
`Formula (1)
`
`where, 0 < z < 2 is satisfied; and X represents Cl or Br.
`
`Advantageous Effects of Invention
`
`[0007] According to the present disclosure, a solid electrolyte material having a high lithium ion conductivity can be
`achieved.
`
`Brief Description of Drawings
`
`[0008]
`
`Fig. 1 is a cross-sectional viewillustrating a schematic structure of a battery 1000 in Embodiment 4.
`Fig. 2 is a perspective viewillustrating the crystal structure of a LigzErBrg structure.
`Fig. 3 is a perspective viewillustrating the crystal structure of a LizErClg structure.
`Fig. 4 is a schematic view illustrating a method for evaluating ionic conductivity.
`Fig. 5 is a graph showing temperature dependenceof the ionic conductivity of solid electrolytes.
`Fig. 6 is a graph showing XRD patterns ofsolid electrolyte materials.
`Fig. 7 is a graph showinginitial discharge characteristics.
`Fig. 8 is a perspective viewillustrating the crystal structure of a LizYbClg structure.
`Fig. 9 is a graph showing temperature dependenceof the ionic conductivity of solid electrolytes.
`Fig. 10 is a graph showing an XRDpattern of a solid electrolyte material.
`Fig. 11 is a graph showinginitial discharge characteristics.
`Fig. 12 is a graph showing an XRDpattern of a solid electrolyte material.
`
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`Description of Embodiments
`
`EP 3 496 202 A1
`
`[0009] Embodiments of the present disclosure will now be described with reference to the drawings.
`
`(Embodiment1)
`
`[0010] The solid electrolyte material in Embodiment 1
`Formula (2):
`
`10
`
`Li3¥Xg
`
`Formula (2)
`
`is a compound represented by the following Compositional
`
`15
`
`20
`
`25
`
`where, X represents Cl (chlorine) or Br (bromine).
`[0011] According to the structure mentioned above, a solid electrolyte material (halide solid electrolytic material) having
`a high lithium ion conductivity can be achieved. In addition, a solid electrolyte material having a structure stable in an
`assumed operation temperature range (e.g., a range of -30°C to 80°C) of a battery can be achieved. Thatis, the solid
`electrolyte material of Embodiment 1 does not have a structure (e.g., the structure in PTL 2) in which the phasetransition
`temperature is present within the operation temperature range of the battery. Consequently, even in an environment
`with temperature change, phase transition does not occur in the operation temperature range of the battery, and a high
`ionic conductivity can be stably maintained.
`[0012] According to the structure described above, an all-solid-state secondary battery having excellent charge and
`discharge characteristics can be achieved by using the solid electrolyte material of Embodiment 1. In addition, an all-
`solid-state secondary battery not containing sulfur can be achieved by using the solid electrolyte material of Embodiment
`1. Thatis, the solid electrolyte material of Embodiment 1 does not have a structure (e.g., the structure in PLT 1) generating
`hydrogen sulfide when exposed to the atmosphere. Accordingly, an all-solid-state secondary battery not generating
`hydrogen sulfide and having excellent safety can be achieved.
`[0013] The solid electrolyte material in Embodiment 1 may include a crystal phase. Examples of the crystal phase
`include a first crystal phase and a second crystal phase described below.
`[0014]
`Thatis, the solid electrolyte material in Embodiment 1 mayinclude a first crystal phase.
`
`[0015] In the first crystal phase, the arrangementof halogenXis the sameasthatof Br in Li,ErBr, (hereinafter, also
`30
`expressed as LEB) having a crystal structure belonging to space group C2/m.
`[0016] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`can be achieved. Specifically, a crystal structure like the first crystal phase allows X to be more strongly attracted to the
`periphery of Y. Consequently, a path through whichlithium ions diffuse is formed. Accordingly, the lithium ion conductivity
`is further improved.
`[0017]
`Fig. 2 is a perspective viewillustrating the crystal structure of a Li,ErBrg structure.
`[0018] As shownin Fig. 2, the Li,ErBrg structure (LEB structure) has monoclinic symmetry and is a crystal structure
`belonging to space group C2/m. The details of the atomic arrangementare available in the inorganic crystal structure
`database (ICSD).
`[0019]
`The first crystal phase having the same halogen arrangement asthat of the LEB structure includes, in a unit
`cell, two of the same compositions represented by Compositional Formula (2).
`[0020] The lattice constants of the unit cell defined by the LEB structure are a = 6.9 to 7.6 angstrom, b = 11.9 to 13.1
`angstrom, c = 6.8 to 7.5 angstrom, a = 90°, B = 109°, and y = 90°.
`[0021] The LEB structure can be identified by structural analysis using X-ray diffractometry. When the measurement
`is performed by a 8-28 method using Cu-Ka rays (wavelength: 1.5405 angstrom and 1.5444 angstrom) as the X-ray,
`strong peaks are observed within the rangesofdiffraction angle 20 values of 25° to 28°, 29° to 32°, 41° to 46°, 49° to
`55°, and 51° to 58°.
`[0022]
`Thesolid electrolyte material in Embodiment 1 maysatisfy ILeB110y/ILEB(200) < 9-01.
`[0023] Herein, ILEB(200) represents the X-ray diffraction intensity of a first crystal phase plane corresponding to the
`(200) plane in the crystal structure of LizErBrg.
`[0024]
` ILeg(110) represents the X-raydiffraction intensity of a first crystal phase plane corresponding to the (110) plane
`in the crystal structure of Li,ErBrg.
`[0025] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`can be achieved. Specifically, irregular arrangement of Y can be achieved. Consequently, the conduction path oflithium
`ions is three-dimensionally connected. Accordingly, the lithium ion conductivity is further improved.
`[0026] As described above, the arrangement of cations of the solid electrolyte material in Embodiment 1 need not be
`the same as the arrangementof cations in the LEB structure. That is, at least part of Y (yttrium) and at least part of Li
`may beirregularly arranged.
`[0027] The irregularity of the arrangement of cations can be evaluated by the above-mentioned intensity ratio
`
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`EP 3 496 202 A1
`
`"ILEB(110)/!LEB(200)"in the XRD pattern.
`[0028] Whenthe arrangement of Yis regular, Lea 10)/ILEB(200) = about 0.02 (about 2%). The value of eB 10)/ILEB(200)
`decreases with an increase in irregularity. As described above,if I_ep(119)/ILEB@oo) < 0.01 (1%), sufficiently irregular
`arrangement of Y can be achieved.
`[0029]
`The solid electrolyte material in Embodiment 1 may satisfy FWHM,/20c, = 0.015.
`[0030] Herein, FWHM, represents the full width at half maximum of an X-ray diffraction peak ofa first crystal phase
`plane corresponding to the (200) plane in the crystal structure of Li,ErBrg.
`[0031]
`In the expression, 26c, denotes the diffraction angle at the center of the X-ray diffraction peak (peak central
`value).
`[0032] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`can be achieved. Specifically, a nonuniform lattice constant can be provided. Consequently, a region having a spread
`in the lattice is formed. Accordingly, the lithium ion conductivity is further improved.
`[0033] Asdescribed above, the lattice constantof the solid electrolyte material in Embodiment 1 need not be completely
`uniform. Thatis, the lattice constant may have some nonuniformity. Specifically, the lattice constant distribution may
`have a full width at half maximum of about 1% or more.
`
`In the solid electrolyte material of Embodiment 1, the structure of the first crystal phase may be distorted, and
`[0034]
`the atoms maybe arrangedatslightly different atomic positions.
`[0035] The solid electrolyte material in Embodiment 1 may include a heterogeneous crystal phase having a crystal
`structure different from that of the first crystal phase.
`[0036]
`In such a case, the heterogeneous crystal phase maylie between the first crystal phases.
`[0037] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`can be achieved. Specifically, the conduction oflithium ions between the first crystal phases is enhanced bythe heter-
`ogeneouscrystal phase. Accordingly, the lithium ion conductivity is further improved.
`[0038] The solid electrolyte material in Embodiment 1 may include an amorphous phase.
`[0039]
`In such a case, the amorphous phase maylie between the first crystal phases.
`[0040] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`canbe achieved. Specifically, the conduction of lithium ions between thefirst crystal phases is enhanced by the amorphous
`phase. Accordingly, the lithium ion conductivity is further improved.
`[0041] The solid electrolyte material in Embodiment 1 may include a second crystal phase.
`[0042]
`In the second crystal phase, the arrangementof halogen X is the same asthat of Cl in Li,ErClg (hereinafter,
`also expressed as LEC) having a crystal structure belonging to space group P-3m1.
`[0043] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`can be achieved. Specifically, a crystal structure like the second crystal phase allows X to be more strongly attracted to
`the periphery of Y. Consequently, a path through which lithium ions diffuse is formed. Accordingly, the lithium ion
`conductivity is further improved.
`[0044]
`Fig. 3 is a perspective viewillustrating the crystal structure of a LizErCl, structure.
`[0045] As shownin Fig. 3, the LiszErClg structure (LEC structure) has trigonal symmetry and is a crystal structure
`belonging to space group P-3m1. The details of the atomic arrangement are available in the inorganic crystal structure
`database (ICSD).
`[0046] The second crystal phase having the same halogen arrangement as that of the LEC structure includes, ina
`unit cells, three of the same compositions represented by Compositional Formula (2).
`[0047] The lattice constants of the unit cell defined by the LEC structure are a = 10.97 to 11.5 angstrom, b = a, c=
`5.9 to 6.2 angstrom, « = 90°, B = 90°, and y = 120°.
`[0048]
`TheLECstructure can be identified by structural analysis using X-ray diffractometry. When the measurement
`is performed by a 9-28 method using Cu-Ka rays (wavelength: 1.5405 angstrom and 1.5444 angstrom) as the X-ray,
`strong peaks are observed within the rangesofdiffraction angle 20 values of 29.8° to 32°, 38.5° to 41.7°, 46.3° to 50.4°,
`and 50.8° to 55.4°.
`
`Thesolid electrolyte material in Embodiment 1 maysatisfy ILEc(110)/ILEc(303) < 9.3.
`[0049]
`[0050] Herein, |_Ec(303) is the X-ray diffraction intensity of a second crystal phase plane corresponding to the (303)
`plane in the crystal structure of LizErClg.
`[0051]
` ILEc(110) is the X-ray diffraction intensity of a second crystal phase plane correspondingto the (110) plane of
`the crystal structure of LizErClg.
`[0052] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`can be achieved. Specifically, irregular arrangement of Y can be achieved. Consequently, the conduction path oflithium
`ions is three-dimensionally connected. Accordingly, the lithium ion conductivity is further improved.
`[0053] As described above, the arrangement of cations of the solid electrolyte material in Embodiment 1 need not be
`the same as the arrangement of cations of the LEC structure. That is, at least part of Y and at least part of Li may be
`irregularly arranged.
`
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`

`EP 3 496 202 A1
`
`The irregularity of the arrangement of cations can be evaluated by the above-mentioned intensity ratio
`[0054]
`“ILEB(1 10)/ILEB(303)" in the XRD pattern.
`[0055] Whenthe arrangement of Yis regular, ILec 4 oy'ILEc(303) > about 0.45 (about 45%). The value of ILec(t 4 0)/ILEc(303)
`decreases with an increase in irregularity. As described above,if ILec(110y/lLEc(303) < 0-30 (80%), sufficiently irregular
`arrangement of Y can be achieved.
`[0056]
`The solid electrolyte material in Embodiment 1 may satisfy FWHM,/20c, = 0.015.
`[0057] Herein, FWHM, representsthefull width at half maximum of an X-ray diffraction peak of a second crystal phase
`plane corresponding to the (303) plane in the crystal structure of Li,ErCl,.
`[0058]
`In the expression, 20c, denotesthe diffraction angle at the center of the X-ray diffraction peak (peak central
`value).
`[0059] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`can be achieved. Specifically, a nonuniform lattice constant can be provided. Consequently, a region havingalattice
`spread is formed. Accordingly, the lithium ion conductivity is further improved.
`[0060] Asdescribed above, the lattice constantof the solid electrolyte material in Embodiment 1 need not be completely
`uniform. Thatis, the lattice constant may have some nonuniformity. Specifically, the lattice constant distribution may
`have a full width at half maximum of about 1% or more.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`In the solid electrolyte material of Embodiment 1, the structure of the second crystal phase maybe distorted,
`[0061]
`and the atoms maybe arrangedatslightly different atomic positions.
`[0062]
`The solid electrolyte material in Embodiment 1 may include a heterogeneous crystal phase having a crystal
`structure different from that of the second crystal phase.
`[0063]
`In such a case, the heterogeneous crystal phase maylie between the second crystal phases.
`[0064] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`can be achieved. Specifically, the conduction oflithium ions between the second crystal phases is enhanced by the
`heterogeneouscrystal phase. Accordingly, the lithium ion conductivity is further improved.
`[0065] The solid electrolyte material in Embodiment 1 may include an amorphous phase.
`[0066]
`In sucha case, the second crystal phase maylie between the second crystal phases.
`[0067] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`can be achieved. Specifically, the conduction oflithium ions between the second crystal phases is enhanced by the
`amorphous phase. Accordingly, the lithium ion conductivity is further improved.
`[0068]
`The solid electrolyte material in Embodiment 1 may have any shape, such as an acicular, spherical, or oval
`spherical shape. For example, the solid electrolyte material in Embodiment 1 may bein a particle form. A plurality of the
`particles may be laminated and then formedinto a pellet or plate by pressurization.
`[0069]
`For example, when the solid electrolyte material in Embodiment 1 is in a particle (e.g., spherical) form, the
`median diameter may be 0.1 ~m or more and 100 p.m or less.
`[0070]
`In Embodiment 1, the median diameter may be 0.5 wm or more and 10 wm or less.
`[0071] According to the structure described above, the ionic conductivity can be further increased. In addition, a more
`satisfactory dispersion state of the solid electrolyte material of Embodiment 1 and an active material or the like can be
`formed.
`
`40
`
`[0072]
`material.
`
`In Embodiment 1, the solid electrolyte material may have a median diameter smaller than that of the active
`
`[0073] According to the structure described above, a moresatisfactory dispersion state of the solid electrolyte material
`of Embodiment 1 and an active material or the like can be formed.
`
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`
`<Method for producing solid electrolyte material>
`
`[0074] The solid electrolyte material in Embodiment 1 can be producedby, for example, the following method.
`[0075] Raw material powders of binary halides are prepared at a blending ratio giving a target composition. For
`example, in the case of producing Li3Y¥Clg, LiCl and YCl, are prepared at a molar ratio of 3: 1.
`[0076]
`In such a case, X in Compositional Formula (2) can be determined by selecting the types of the raw material
`powders. The raw material powders are sufficiently mixed and are then mixed, pulverized, and reacted with each other
`using a mechanochemical milling process. Alternatively, the raw material powders are sufficiently mixed and may be
`then sintered in vacuum.
`
`[0077] Consequently, a solid electrolyte material having a crystal phase described aboveis given.
`[0078]
`The structure of the crystal phase (crystal structure) of the solid electrolyte material can be determined by
`adjusting the reaction method and reaction conditions for the raw material powders.
`
`

`

`(Embodiment2)
`
`EP 3 496 202 A1
`
`[0079] Embodiment 2 will now be described. The description overlapping with Embodiment 1 described above is
`omitted as appropriate.
`[0080] The solid electrolyte material in Embodiment 2 is a compound represented by Compositional Formula (1):
`
`Lig.,Y,Xg
`
`Formula (1)
`
`where, 0 < z < 2 is satisfied; and X represents Cl or Br.
`[0081] According to the structure mentioned above, a solid electrolyte material (halide solid electrolytic material) having
`a high lithium ion conductivity can be achieved. In addition, a solid electrolyte material having a structure being stable
`in the assumed operation temperature range (e.g., a range of -30°C to 80°C) of the battery can be achieved. Thatis,
`the solid electrolyte material of Embodiment 2 does not have a structure (e.g., the structure in PTL 2) in which the phase
`transition temperature is present within the operation temperature range of the battery. Consequently, even in an envi-
`ronment with temperature change, phase transition does not occur in the operation temperature range of the battery,
`and a high ionic conductivity can be stably maintained.
`[0082] According to the structure described above, an all-solid-state secondary battery having excellent charge and
`discharge characteristics can be achieved by using the solid electrolyte material of Embodiment 2. In addition, an all-
`solid-state secondary battery not containing sulfur can be achieved by using the solid electrolyte material Embodiment
`2. Thatis, the solid electrolyte material of Embodiment 2 does not have a structure (e.g., the structure in PLT 1) generating
`hydrogen sulfide when exposed to the atmosphere. Accordingly, an all-solid-state secondary battery not generating
`hydrogen sulfide and having excellent safety can be achieved.
`[0083] The solid electrolyte material in Embodiment 2 satisfies 0.75 < z < 1.5.
`[0084] According to the structure described above, a solid electrolyte material (halide solid electrolytic material) having
`a higherlithium ion conductivity can be achieved. In addition, an all-solid-state secondary battery having more excellent
`charge and discharge characteristics can be achieved.
`[0085] The solid electrolyte material in Embodiment 2 satisfies 1 < z < 1.25.
`[0086] According to the structure described above, a solid electrolyte material (halide solid electrolytic material) having
`a higherlithium ion conductivity can be achieved. In addition, an all-solid-state secondary battery having more excellent
`charge and discharge characteristics can be achieved.
`[0087] The solid electrolyte material in Embodiment 2 may include a crystal phase. Examples of the crystal phase
`include a first crystal phase and a third crystal phase described below.
`[0088]
`Thatis, the solid electrolyte material in Embodiment 2 mayinclude a first crystal phase.
`[0089]
`In the first crystal phase, the arrangementof halogen X is the sameasthat of Br in LizErBrg (hereinafter, also
`expressed as LEB) having a crystal structure belonging to space group C2/m.
`[0090] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`can be achieved. Specifically, a crystal structure like the first crystal phase allows X to be more strongly attracted to the
`periphery of Y. Consequently, a path through whichlithium ions diffuse is formed. Accordingly, the lithium ion conductivity
`is further improved.
`[0091] As shownin Fig. 2, the LizErBrg structure (LEB structure) has monoclinic symmetry and is a crystal structure
`belonging to space group C2/m. The details of the atomic arrangementare available in the inorganic crystal structure
`database (ICSD).
`[0092]
`The first crystal phase having the same halogen arrangement asthat of the LEB structure includes, in a unit
`cell, two of the same composition represented by Compositional Formula (1).
`[0093] The lattice constants of the unit cell defined by the LEB structure are a = 6.9 to 7.6 angstrom, b = 11.9 to 13.1
`angstrom, c = 6.8 to 7.5 angstrom, a = 90°, B = 109°, and y = 90°.
`[0094]
`TheLEB structure can be identified by structural analysis using X-ray diffractometry. When the measurement
`is performed by a 9-28 method using Cu-Ka rays (wavelength: 1.5405 angstrom and 1.5444 angstrom) as the X-ray,
`strong peaks are observed within the rangesofdiffraction angle 20 values of 25° to 28°, 29° to 33, 41° to 47°, 49° to
`55°, and 51° to 58°.
`[0095]
`Thesolid electrolyte material in Embodiment 2 maysatisfy I_EB(110y/ILEB(200) < 9-01.
`[0096] Herein, I_EB(200) represents the X-ray diffraction intensity of a first crystal phase plane corresponding to the
`(200) plane in the crystal structure of Li,ErBrg.
`[0097]
`les 10) represents the X-raydiffraction intensity of a first crystal phase plane corresponding to the (110) plane
`in the crystal structure of Li,ErBrg.
`[0098] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`can be achieved. Specifically, irregular arrangement of Y can be achieved. Consequently, the conduction path oflithium
`ions is three-dimensionally connected. Accordingly, the lithium ion conductivity is further improved.
`
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`EP 3 496 202 A1
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`[0099] As described above, the arrangement of cations of the solid electrolyte material in Embodiment 2 need not be
`the same as the arrangementof cations of the LEB structure. That is, at least part of Y and at least part of Li may be
`irregularly arranged.
`[0100] The irregularity of the arrangement of cations can be evaluated by the above-mentioned intensity ratio
`"ILeB(1 10)lLeB(2oo)" in the XRD pattern.
`[0101] Whenthe arrangementof Y is regular, |,Eg(110y/!LeB(2oo) = about 0.02 (about 2%). The value of |,EB(110)/!LEB200)
`decreases with an increase in irregularity. As described above,if I,eB(110y/lLeBio0) < 9-01 (1%), sufficiently irregular
`arrangement of Y can be achieved.
`[0102] The solid electrolyte material in Embodiment 2 may satisfy FWHM,/20c, = 0.015.
`[0103] Herein, FWHM, represents the full width at half maximum of an X-ray diffraction peak ofa first crystal phase
`plane corresponding to the (200) planein the crystal structure of Li,ErBrg.
`[0104]
`In the expression, 26c, denotes the diffraction angle at the center of the X-ray diffraction peak (peak central
`value).
`[0105] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`15
`can be achieved. Specifically, a nonuniform lattice constant can be provided. Consequently, a region havingalattice
`spread is formed. Accordingly, the lithium ion conductivity is further improved.
`[0106] Asdescribed above, the lattice constantof the solid electrolyte material in Embodiment 2 need not be completely
`uniform. Thatis, the lattice constant may have some nonuniformity. Specifically, the lattice constant distribution may
`have a full width at half maximum of about 1% or more.
`
`10
`
`20
`
`In the solid electrolyte material of Embodiment 2, the structure of the first crystal phase may be distorted, and
`[0107]
`the atoms maybe arrangedatslightly different atomic positions.
`[0108] The solid electrolyte material in Embodiment 2 may include a heterogeneous crystal phase having a crystal
`structure different from that of the first crystal phase.
`[0109]
`In such a case, the heterogeneous crystal phase maylie between the first crystal phases.
`[0110] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`can be achieved. Specifically, the conduction oflithium ions between the first crystal phases is enhanced bythe heter-
`ogeneouscrystal phase. Accordingly, the lithium ion conductivity is further improved.
`[0111] The solid electrolyte material in Embodiment 2 may include an amorphous phase.
`[0112]
`In such a case, the amorphous phase maylie between the first crystal phases.
`[0113] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`canbe achieved. Specifically, the conduction of lithium ions between thefirst crystal phases is enhanced by the amorphous
`phase. Accordingly, the lithium ion conductivity is further improved.
`[0114] The solid electrolyte material in Embodiment 2 mayinclude a third crystal phase.
`
`[0115] Inthe third crystal phase, the arrangement of halogenXis the sameasthat of Cl in LizYbClg (hereinafter, also
`35
`expressed as LYC) having a crystal structure belonging to space group Pnma.
`[0116] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`can be achieved. Specifically, a crystal structure like the third crystal phase allows X to be morestrongly attracted to
`the periphery of Y. Consequently, a path through which lithium ions diffuse is formed. Accordingly, the lithium ion
`conductivity is further improved.
`[0117]
`Fig. 8 is a perspective view illustrating the crystal structure of a LizYbClg structure.
`[0118] As shownin Fig. 8, the LizYbClg structure (LYC structure) has orthorhombic symmetry and is a crystal structure
`belonging to space group Pnma. The details of the atomic arrangementare available in the inorganic crystal structure
`database (ICSD).
`[0119] The third crystal phase having the same halogen arrangementasthat of the LYC structure includes, in a unit
`cell, three of the same compositions represented by Compositional Formula (1).
`[0120] The lattice constants of the unit cell defined by the LYC structure are a = 12.8 to 13.5 angstrom, b = 11.1 to
`12.0 angstrom, and c = 5.90 to 6.10 angstrom.
`[0121] TheLYC structure can be identified by structural analysis using X-ray diffractometry. When the measurement
`is performed by a 9-29 method using Cu-Ka rays (wavelength: 1.5405 angstrom and 1.5444 angstrom) as the X-ray,
`strong peaks are observed within the rangesofdiffraction angle 20 values of 29.8° to 32°, 38.5° to 41.7°, 46.3° to 50.4°,
`and 50.8° to 55.4°.
`
`40
`
`25
`
`30
`
`45
`
`50
`
`[0122] The solid electrolyte material in Embodiment 2 may satisfy FWHM./20c3 = 0.015.
`[0123] Herein, FWHMz, represents the full width at half maximum of an X-raydiffraction peak of a third crystal phase
`plane corresponding to the (231) planein the crystal structure of Li,YbClg.
`[0124]
`In the expression, 26c, denotes the diffraction angle at the center of the X-ray diffraction peak (peak central
`value).
`[0125] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`can be achieved. Specifically, a nonuniform lattice constant can be provided. Consequently, a region havingalattice
`
`55
`
`

`

`EP 3 496 202 A1
`
`spread is formed. Accordingly, the lithium ion conductivity is further improved.
`[0126] Asdescribed above, the lattice constantof the solid electrolyte material in Embodiment 2 need not be completely
`uniform. That is, the lattice constant may have some nonuniformity. Specifically, the lattice constant distribution may
`have a full width at half maximum of about 1% or more.
`
`In the solid electrolyte material of Embodiment 2, the structure of the third crystal phase may bedistorted, and
`[0127]
`the atoms maybe arrangedatslightly different atomic positions.
`[0128] The solid electrolyte material in Embodiment 2 may include a heterogeneous crystal phase having a crystal
`structure different from that of the third crystal phase.
`[0129]
`In such a case, the heterogeneous crystal phase maylie between the third crystal phases.
`[0130] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`can be achieved. Specifically, the conduction of lithium ions between the third crystal phases is enhancedby the heter-
`ogeneouscrystal phase. Accordingly, the lithium ion conductivity is further improved.
`[0131] The solid electrolyte material in Embodiment 2 may include an amorphous phase.
`[0132]
`In such a case, the amorphous phase maylie betweenthe third crystal phases.
`[0133] According to the structure described above, a solid electrolyte material having a higherlithium ion conductivity
`can be achieved. Specifically, the conduction oflithium ions between the third crystal phases is enhanced by the amor-
`phous phase. Accordingly, the lithium ion conductivity is further improved.
`[0134] The solid electrolyte material in Embodiment 2 may have any shape, such as an acicular, spherical, or oval
`spherical shape. For example, the solid electrolyte material in Embodiment 2 may bein a particle form. A plurality of the
`particles may be laminated and then formedinto a pellet or plate by pressurization.
`[0135]
`For example, when the solid electrolyte material of Embodiment 2 is in a particle (e.g., spherical) form, the
`median diameter may be 0.1 ~m or more and 100 p.m or less.
`[0136]
`In Embodiment 2, the median diameter may be 0.5 wm or more and 10 wm or less.
`[0137] According to the structure described above, the ionic conductivity can be further increased. In addition, a more
`satisfactory dispersion state of the solid electrolyte material of Embodiment 2 and an active material or the like can be
`formed.
`
`[0138]
`material.
`
`In Embodiment 2, the solid electrolyte material may have a median diameter smaller than that of the active
`
`[0139] According to the structure described above, a more satisfactory dispersion state of the solid electrolyte material
`of Embodiment 2 and an active material or the like can be formed.
`
`