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`JP2OUSSS0094 LITHIUM CELL ELEMENT
`
`Applicants: TOKYO INST TECH
`
`inventors: SONDO SHIGEO, SUGANO RIYOL YAMADA ATSUD
`
`Classiioagtions:
`
`BS
`
`HOIMIQOQS2: HOTMIO/GSE2; HOTMAG\G58; HOTT GG58S8, NOMA: HOT M48a;
`ORCS y HOUMTGSS: HOUM4/G2: NOTM482:
`
`Publication: JP2O0505930
`
`Pubtshad aa: JP20093S32004] P8078 124 R2
`
`LITHIUM CELL ELEMENT
`
`Abstract
`
`«P> PROBLEM TO BE SOLVED: To improve cycie degradation property, mechanical sirangth or short ciroust
`nature of an inorganic all solid state batiery. <P>SOLUTION: A ithium cel elernent inchucies « Hthlum fon
`conductive solic siectrotyle layer provided befiween a palr of a oosilive electrode layer and a neqalive
`siectrode fayer which cen oenlude end discharge ithium. in the ithiura cell element, an intermediate hayer for
`forming @ material isyyer having a higher electrode potential than the Bihhum in reaction with tie bihhunmis
`provided befween the negative electrode layer and the siectroijie layer. The Hihtum cell clament includes a
`Sthiurn fom caorductive inorganic sold electrode layar prodded belween the pair of fhe positive electrode and
`
`the nesedive shectrods layer which can occlude and diechargue the Wthiurn. At feast ons of the positive
`alsctrods Layer and the negative electrode layer containe powder mld filed in the opening of a mesh.
`<PoCOPYRIGHT: (032006, JPOSNCIF!
`
`worldwide.espacenet.conypatentsearch’fanuly/03 55876 | 4/nublication/IP2008....
`
`
`2O20/O3{12
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`

`

`
`
`Notice
`This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
`complete, reHable or fit for specific purposes. Critical decisions, such as commercially relevant or
`financial decisions. should not be based on machine-translation output.
`
`CLAIMS JP2003353309
`
`1.
`A lithium battery element comprising a lithium ion conductive inorganic solid electrolyte layer
`provided between a pair of a positive electrode layer and a negative electrode layer capable of
`inserting and extracting lithium, wherein ithium reacts with Ithiumbetween the negative
`electrode layer and the electrolyte layer. And an intermediate layer for forming a material layer
`having an electrode potential higher than that of ithium,
`
`2.
`The lithium battery clement according to claim 1, wherein the inorganic solid electrolyte includes
`a sulfide-based inorganic solid electrolyte.
`
`2 +
`
`The lithium battery element according to claim 2, wherein the sulfide-based inorganic solid
`electrolyte includes crystalline lithiumgermaniumthiophosphate.
`
`4.
`
`The Hthium battery element according to any one of claims 1 to 3. wherein the intermediate layer
`contains aluminum.
`
`3.
`
`A lithium battery element comprising an inorganic solid electrolyte layer containing a sintered
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`badyof crystalline lithium germaniumthiophosphate provided betweena pair of a pasitive
`electrode layer and a negative electrade layer capable of inserting and extracting lithium,
`
`5.
`A lithium battery element having a lithium ion conductive Inorganic solid electrolyte layer
`provided betweena pair of a positive electrode layer and a negative electrode layer capable of
`inserting and extracting lithium, wherein at least one of the positive electrode layer and the
`negative electrode layer has an opening of a mesh. A lithhum battery element comprising a
`powder molded bodyfilled in a part.
`
`7.
`A lithium battery element comprising a lithium ion conductive inorganic solid electrolyte layer
`provided between a pair of a positive electrodelayer ane a negative electrode layer capable of
`inserting and extracting lithiurn, wherein a mesh is arrariged between the negative electrode
`layer and the electrolyte layer. A lithium battery clement, characterized in that the opening of the
`mesh is fled with the electrolyte.
`
`8.
`
`A lithium battery element comprising a lithiumion conductive inorganic solid electrolyte layer
`provided betweena pair of a positive electrodelayer and a negative electrode layer capable of
`inserting and extracting lithiurn, wherein Hthiumreacts with lithiumbetween the negative
`electrode layer and the electrolyte layer. An intermediate layer for forming a material layer
`having an electrode potential higher than thatof lithiumis provided, and a meshis further
`arranged between the intermediate layer and the electrolyte layer to fill an opening of the mesh
`with the electrolyte. Lithium battery element.
`
`8.
`
`The lidhium battery element according to claim 6, whereinat least one peripheral portion ofthe
`meshis filled with the inorganic sold electrolyte,
`
`10.
`
`The lithium battery element according to any one of claims 6 to G, wherein the meshis
`electronically conductive.
`
`it.
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`The lithium battery element according to any one of claims 6 to 9. wherein the mesh is Nthivm
`ion conductive.
`
`12.
`
`The Uthium battery element according to any one of claims | to 11, wherein at least one of the
`pasitive electrode layer, the inorganicsolid electrolyte layer, and the negative electrode layer
`contains a polymer binder.
`
`13.
`
`The Hthiumbattery clement according to claim 12, wherein the polymer binder coruprises a
`cured product.
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`
`
`Notice
`This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
`complete, reHable or fit for specific purposes. Critical decisions, such as commercially relevant or
`financial decisions. should not be based on machine-translation output.
`
`DESCRIPTIONJP2005353309
`
`PROBLEM TO BE SOLVED: To Smprove the oycle deterioration property, mechanical strength or
`short-circuit property of an inorgartic all solid state battery. SOLUTION: This lithium batrery
`element comprises a lithium ion conductive inorganic solid electrolyte layer provided between a
`pair of a positive electrode layer and a negative electrode layer capable of inserting and
`extracting lithium, wherein a lithium ion conductive inorganic solid electrolyte layer is provided
`between the negative electrode layer and the electrolyte layer. And an intermediatelayer that
`reacts with lithiumto form a material layer having a higher electrode potential than Hthium. A
`Hthiumbattery element having a lithhim ion canductive inorganic solid electrolyte layer provided
`between a pair of a positive electrode layer and a negative electrode layer capable of inserting
`and extracting lithium, wherein at least one of the positive electrade layer and the negative
`electrode layer has an opening of a mesh. A lithiumbattery element comprising a powder molded
`bodyfilled in a part. [Selection diagram| Fig.
`|
`
`Lithiumbattery element
`
`{O001}
`The present invention relates to a lithium battery using a lithium ion conductive inorganic solid
`electrolyte in which a mobile ion species is lithium jon.
`
`foGO2])
`
`In recent years, with the develapment of portable devices such as personal computers and mobile
`phones, the demand for batteries as power sources has become extremelylarge.
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`In particular, lithiumbatteries are substances that have a low atomic weight of lithivun and a high
`ionization energy. and thus have been actively studied as batteries capable of obtaining high
`energy densities, and are now widely used as power sources for portable devices. Have been.
`
`{OGO3]
`
`In recent years, as the performance of a device using a Hthiumbattery has been improved,
`demands for not only battery capacity and charge / discharge cycle life but also a variety of
`shapes have become apparent. For example, a thinnercell structure has been required. On the
`other hand, due to an increase in internal energy due to an increase in the amountof active
`material contained and an increase in the cornent of an organic solvent which is a flammable
`substance used in the electrolyte, dangers suchas ipnition of batteries have recently been
`highlighted. I have.
`
`{OO04]
`
`In view ofthe above, there is an increasing demand for ithiumbatteries to be thin anid more
`desirablyall-solid type containing no organic solvent. Therefore, as a lithhum battery having
`excellent shape processability and / or high safety, all-salid-state batteries using a solid
`electrolyte in which the organic solvent-basedelectrolyte is replaced with a solid have been
`actively studied. Among these, as a solid electrolyte type, research on a polymergel electrolyte
`confined in a three-dimensional netwark structure of a polymer, a polymerelectrolyte containing
`no organic solvent at all, and an inorganic solid electrolyte has been actively advanced.
`
`{O00S}
`
`Amonp these materials, the polymer pel electrolyte still contains an organic solvent, so that its
`safety is not perfect. Further, in the case of a polymerelectrolyte containing no organic solvent,
`practical conductivity has not yet been obtained due to lowHthiumjon conductivity and / or low
`lithiumion trarmsport number. In terms of conduction characteristics, inorganic solid electrolytes
`are cansidered to be most suitable.
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`{OQ06}
`
`Regardless ofthetype of electrolyte used, these electralytes have both the role of an electrolyte
`in a conventional lithiumion battery and the role of a separator separating an electrode from a
`positive electrode and a negative electrode. Therefore, the basic structure ofa solid batteryis a
`laminated structure in which a solid electralyte is provided betweena pair of a pasitive electrode
`and a negative electrade, and when the positive and negative electrodes are powder molded
`badies, the solid electrolyte is also contained in the molded bodies. That is conmnon.
`
`{OGO07}
`
`Although research into thinning of solid-state batteries is progressing, lamination of electrodes
`and electrolytes becomes extremely difficult as each becames thirmer. As a specific problemthat
`occurs, for example, fa hole is forrned m the electrolyte layer during the operation of the
`battery, a short circuit occurs immediately between the positive electrode and the negative
`electrode. Since a large current flows at the time of shortcircuit, intense heat peneration occurs,
`which is extremely dangerous. In the case of a system containing anelectrolyte, such heat
`generation not only raises the battery temperature ta a region exceeding the ignition point of the
`electrolyte, but also promotes the decomposition reaction of the electrode material to induce
`further heat generation, which sometimes causes the battery to explode. Reach.
`
`{0008}
`
`Even with a polymer electrolyte containing no electrolyte, a high temperature at the time of a
`shortcircuit maycause the polymer to decompose and melt, leading to an increase in imernal
`pressure, Some inorganic solid electrolytes are stable up to about GOO” C., and there is no
`danger as described above, However, if they are short-circuited, they no longer function as a
`battery, leading to shutdownorfailure of mounted equipment. Therefore, although the solid
`electrolyte should originally have the function of a separator, it is necessaryto take extra
`measures such as introducing an extra separator material,
`
`{OGO9}
`
`However, the separator is still applicable as long as it is a polymer gel electrolyte system
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`containing an organic solvent.However, in an electrolyte system with a view to drastic safety, that
`is. a polymer electrolyte containing no organic solvent or an inorganic solid electrolyte, the
`separatoris high. It can be a resistance layer. In order to prevent such a short circuit without
`relying on the separator, it is desirable to adopt a method of stably forming the electrolyte
`directly on the smooth electrode layer.
`
`{OG LO]
`
`As a manuacturing method in. which a solid battery using an inorganic solid electrolyte has been
`actively researched recently, a thin film laminated battery by a vacuumevaporation method can
`be memioned (Abe, Electrochemistry and Industrial Physical Chemistry, 71 (2003) 728). These
`are extremely promising, with the expectation of realizing an on-chip battery with a view to
`applications in special Helds such as space applications {US Pat.No. 6,558,836).
`
`jOOL1)
`
`However. a solid-state battery using an inorganic solid electrolyte has a problem of cycle
`deterioration in which the resistance increases at the interface between the negative electrode
`and the electrolyte as charging and discharging are repeated, and as a result, the capacity of the
`battery decreases. In addition, thin-film solid-state batteries have high potential, but are not onhy
`experisive at present, but are not realistic for obtaining large-sized batteries applicable to vehicle-
`mourned applications such as electric vehicles and hybrid vehicles. Absent. In order to be useful
`in a wide range of industries, it is inexpensive if an electrode layer or an electrolyte layer can be
`formed by a very versatile coating method such as dipping, doctor blade, or screen printing, and
`a large-area film can be obtained. So desirable. Such a solid state battery is generally called a bulk
`type solid state battery (Abe, Electrochemical and Industrial Physical Chemistry, 71 (2003) 728
`Bulk-type solid batteries are already being evaluated for their characteristics in coin batteries,
`etc, (K. Takada, T. Inada, A. Kajiyama, H. Sasaki, S$, Kondo, M. Watanabe, M. Murayama, and R
`Kanno, Solid State Ionics, 158 (2003) 269.) Whenthe size is increased, the electrode and the
`electrolyte material are generally inorganic powders, and there is a concern thatstrengthis
`reduced dueto its high brittleness.
`
`[OG12]
`forest,
`US. PatWNo. 6.598,836 Abe, Electrochemistry and Industrial Physical Chentistry. Vol. 71. 728,
`2003. Journal of Electrochemical Society, Volume 148, Issue 7, Pages A742-A746, 2001
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`{OO1S}
`
`An object of the present invention is to provide an inorganic solid electrolyte-based lithium
`battery element in which cycle deterioration is suppressed.
`
`Anatherobject of the present invention is to provide a highly safe and reliable bulk type all-solid
`lithium clectrode having excellent mechanical strength even when a uniformelectrode /
`electrolyte laminatedlithium battery element having high ion diffusivity is manufactured bya
`general-purpose coating method, An object of the present invention is to provide a battery
`element configuration from which a battery can be obtained,
`
`{OO1A]
`
`‘The present inventors have conducted intensive studies and as a result, by providing an
`intermediate layer between the negative electrade layer and the electrolyte layer to forma
`material layer having a higher electrode potential than lithiumby reacting withlithium, it is
`possible to suppress cycle deterioration of the battery. | found that. In addition, by employing a
`configuration in which a mesh is provided in the electrode layer and the opening of the meshis
`Hled with an electrode mixture, a battery element can be manufactured by a general-purpose
`coating method, and the strength of the battery element is dramatically increased. Found to
`improve. Furthermore, it has been found that a structure for preventing a short circuit between
`the positive and negative electrodes is obtained by filling the peripheryof the electrode filler in
`the mesh with the electrolyte material, and the battery can be easily thinned.
`
`fOO1 5]
`
`That is, the present invention is as follows. (1) A lithium battery element comprising a lithiumjon
`conductive inorpanic solid electrolyte layer provided between a pair of a positive electrode layer
`and a negative electrode layer capable of inserting and extracting lithium, wherein a lithium fon
`conductive inorganic soHd electrolyte layer is provided between the negative electrode layer and
`the electrolyte layer. A lithium battery element comprising an intermediate layer that reacts with
`Hthivan to form a material layer having a higher electrode potential than lithium. (2) The lithtum
`battery clement according to (1), wherein the inorganic solid electrolyte inchides a sulfide-based
`inorganic solid electrolyte. (3) The lithium battery element according to (2), wherein the sulfide-
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`based inorganic solid electrolyte contains crystalline lithium germaniumthiophosphate. (4) The
`lithium battery element according to any one of (1) to (3), wherein the intermediate layer
`contains aluminum. (5) A lithium battery element having an inorganic solid electrolyte layer
`including a sintered bodyof crystalline lithium: germaniumthiophosphate provided between a
`pair of a positive electrode layer and a negative electrode layer capable of inserting and
`extracting lithium. (6) A lithiumbattery element comprising a lithium ion conductive inorganic
`solid electrolyte layer provided betweena pair of a positive electrode layer capable of inserting
`and extracting lithium and a negative electrode layer, wherein at least one of the positive
`electrode layer and the negative electrode layer is provided. A lithiumbattery element
`comprising a powder compact filled in an opening of a mesh. (7} A lithium battery clement
`having a lithium ion conductive inorganic solid electrolyte layer provided between a pair of a
`positive electrode layer and a negative electrode layer capable of inserting and extracting lithium,
`wherein a meshis provided between the negative electrode layer and the electrolyte layer.
`Wherein the electrolyte is filled in the openings of the mesh. (8) A lithium battery element
`comprising a lithiurn ion conductive Inorganic solid electrolyte layer provided between a pair of a
`positive electrode layer capable of inserting and extracting lithiumand a negative electrade layer,
`wherein a lithiumjon conductive inorganic solid electrolyte layer is provided between the
`negative electrode layer and the electrolyte layer. An intermediate layer that reacts with lithium
`to form a material layer having a higherelectrode potential than lithium is provided, and a mesh
`is arranged between the intermediate layer and the electrolyte layer to fl an opening of the
`mesh with the electrolyte: A Hthium battery element comprising: (9) The lithium battery element
`according to (6), wherein af least one peripheral portion of the mesh is filled with the inorganic
`solid electrolyte. (10) The lithiumbattery element according to ary one of(6) to (9), wherein the
`mesh is electronically conductive. (11) The lithium battery elemern. according to any one of(6) to
`{9}, wherein the meshis lithium ion conductive, (12) The lithiumbattery element according to
`any one of (1} to (11), wherein at least one of the positive electrode layer, the inorganic solid
`electrolyte layer, and the negative electrode layer contains a polymerbinder.
`
`(13) The lithium battery element according to (12), wherein the polymer binder comprises a
`cured product.
`
`fOo16)
`
`By providing the intermediate layer between the negative electrode layer and the electrolyte
`layer according to the present invention, cycle deterioration of the inorganic solid electrolyte
`Hthivan battery element can be suppressed. Further, by providing theelectrode layer with a mesh
`according to the present invention, a bulk-type inorganic all-solid battery having excellent
`mechanical streneth can be manufactured by a general-purpose coating method. At this time, by
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`filling the periphery of the electrode filler in the mesh with the electrolyte material, a short
`circuit between the positive and negative electrodes can be prevented.
`
`{OOL 7}
`
`As the material of the Hthiumion conductive inorganic solid electrolyte layer according to the
`present Invention, an inorganic solid electrolyte having a lithtum ion transport number of1,
`particularly a sulfide-based inorganicsolid electrolyte having a high lithium ion conductivity and
`a high decomposition potential is preferable. . The electrolyte can be used alone or in
`combination of two or more, The lithiumion transport number will be described later in detail in
`the description of the polymer binder. The sulfide-based inorganic solid electrolyte contains
`sulfur as one of the constituent elements, and is generally synthesized by combining Li2S and at
`least onesulfide selected from P2S5, GeS2, Sind, BeS3, and the like. Also, a material obtained by
`doping the sulfide with a small amount of an orthoacid such as LiSPO4 ar a material coraining a
`Hthium halide such as Lilis known. These may be used alone oar in combination.
`
`{OOLS}
`
`Morespecifically, LOPLISPO-4.0.631Li1280.3645iS2 (N. Aotani, K. lwarmoto, K. Takada, andS.
`Kondo, Solid State Ionics, 68, (1994) 35.); 451310.55 (0.69Li2S. 0.31 P2S5) (R. Mercier, FP
`Malugani, B. Fahys, and G. Robert, Solid State tonics, 5, (1981) 663.}, Q45LiL 55
`{0.691128.0.31B283) CH. Wada, M. Menetrier, A. Levasseur, and P. Hagentmuller, Mat. Res. Bill,
`18 (1983) 189), and lithium germaniumthiophosphate having a composition such as
`LiS.25Ge0.25P0.75584 (RK. Kanno and M. Murayama, J. Electrochemical Soc, 148 (20014) A742. ).
`In particular, the lithium germanium thiophosphate has a structure of y -LISPO4type, and has a
`general composition formula Lid-xM1-yM’yS4 @where M and M‘are Ge or Siand P, Al or Ga,
`respectively. Wherein x ranges from -] to +] and y ranges from 0 to 1).
`
`fOo19)
`
`Inorganic solid electrolytes are roughlyclassified into amorphous ones and crystalline ones.
`Amorphous materials are crystallized by heating and their ionic conductivity is reduced, but
`crystalline electrolytes do not undergo such deterioration and have high thermal stability. It is
`positioned as having a wide range, which is more desirable. As such a crystalline electrolyte, the
`above-mentioned lithium germanium thiophosphate (eg, Li3.25Ge0.25P0.75S84) exhibits a high
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`

`ionic conductivity as high as 2 =< 1Q<-3> 8 / cm at roomtemperature. And it is stable up to
`about 600° C. In addition, lithium germanium thiophosphate has a lowactivation energyfor
`ion conduction and is expected to have good low-temperature characteristics.
`
`{0020}
`
`The inorganic solid electrolyte is used after being pulverized to about | to 5 yom. In the case of a
`sulfide-based material, it is pulverized in an atmosphere of dry argon or the like because it has a
`strong hydrolysis property. Examples of the pulverizing method include a vibration mill and a
`planetary ball mill, In the present invention, the particle diameter is visually observed by SEM
`observation, but it is also passible to evaluate by a method of classifying with an electroform
`sieve or a net sieve, or by an optical methodsuch aslaser scattering.
`
`{O02 1}
`
`The pulverized inorganic solid electrolyie is put into a solvent to prepare a Slurry oftheinorganic
`solid electrolyte, and the electrolyte layer can be formed by a general-purpose coating method
`such as a dipping method, a doctor blade method, or a screen printing method. As the solvent, it
`is necessary to select a solvent that does not easily deteriorate the Inorganic solid electrolyte. In
`particular, since sulfide-based inorganic solid electrolytes generally have strong hydrolyzability,
`use nonpolar aprotic salvents represented by hydrocarbon solvents such as hexane, heptane,
`octane, nonane, decane, decalin, toluene, and xylene. Is preferred. in addition, the water content
`of the solvent is reduced to 10 ppm or less, preferably 1 ppmor less by a known method (for
`example, Guide to Organic Chemistry Experiment 1 Chapter 5 (Chemical Doujinshi}), and slurry
`preparation and coating operation are performed using argon. It is desirable to performin an
`environment where the amount of moisture is controlled, such as a replacement glove box, Here,
`the material to be coated maybe an imtermediate layer material ar a mesh material according to
`an embodiment of the present invention. After the coating, the solvent is sufficiently removed
`under reduced pressure to form an electrolyte layer.
`
`{0022}
`
`Thethickness of the electrolyte layer is in the range of 10 to 200 jm, preferably 15 to SOQ yom.
`If itis too thin, problems such as a short circudl occurring during operation, a reduction in
`product yield, and the like occur. On the other hand, if the thickness is too large, the proportion
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`

`of the electrolyte layer in the battery increases, which causes a problem that the energy density
`of the battery decreases.
`
`{OG23])
`
`Next, the electrode material will be described. The positive electrodeis usually a powder mixture,
`and is a mixture containing a positive electrode active material capable of Inserting and
`extracting lithium ions and at least one kind of lithium ion conductive solid electrolyte. As the
`type of the positive electrode active material, any potential can be applied as long as the potential
`at the thne of charge and dischargeis lower than the oxidative decomposition potential ofthe
`electrolyte and higher than the potential of the negative electrode active material described later.
`Transition metal oxides such as lithium oxide, lithium manganate, and lithium nickelate, or solid
`solutions thereof, for example, lithium cobalt nickelate, and the Eke. Also, polyanion compounds
`such as LiFePO4 olivine compounds and their analogs are applicable. Further, transition metal
`sulfides such as Mo6S8 chevrel compounds andanalogs (for example, Cu2MoGS8) cari be
`mentioned. Further, a layered sulfide such as TiSe is also applicable.
`
`[Q024|
`
`As the solid electrolyte contained in the positive electrode, one or more of the materials used for
`the electrolyte layer can be selected and applied, and among them, a crystalline sulfide-based
`inorganic solid electrolyte is most preferable. The positive electrode mixture maycontain a
`conductive additive.Examples of the type ofthe conductive additive include a carbon material
`and a metal material Examples of the carbon material include carbon black such as acetylene
`black and Ketjen black, anda graphite material, Examples of the metal material include a metal
`and a conductive oxide. It is desirable that all of the materials have a fine particle or beaded
`structure and are dispersed in the positive electrode layer in a state of being dispersed or
`forming a network, In that respect, carbon black and structured metal nanoparticies are
`desirable,
`
`{0025}
`
`Thepositive electrade layer can be formed in the same manner as the above-described Inorganic
`solid electrolyte layer. That is, a powder mixture of the posiive electrode material may be
`prepared ina slurry with the salvent described above for forming the electrolyte layer, and then
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`formed into a film bythe same coating method. Here, the material to be coated is a current
`collector sheet or a mesh thereon according to the embadimentof the present invention. The
`thickness of the positive clectrade layer is in the range of 1 to 1000 jem, preferably 30 to 500
`
`pm.
`
`jO026)
`
`The negative clectrode is, for example, lithium, a metal capable of occluding lithium, or an alloy
`containing lithium, or a material obtained by filling these materials in a porous material such as
`Sic, a carbon material, a LiCoN-based ceramic material (hereinafter, referred to as LiCoN}, or the
`like, Is mentioned. Examples of the carbon material include graphite and hard carbon. Lithium
`may be used as it is. Lithium often has a carbonic acidlayer or an oxide layer on the surface.
`Therefore, it is desirable to use the lithiumJayer affer removing the surface layer by a mechanical
`method such as polishing as much as possible.
`
`{0027
`
`Examples of the metal capable ofstoring lithiuminchide indium, aluminum, tin, germanium, and
`silicon. These maybe preliminarily bonded with lithium on the main surface opposite to the main
`surface in contact with the electrolyte. Examples of the alloy containing lithiuminclude alloys of
`indium, aluminum, tin, germanium, andsilicon. These materials may be surface-modified with a
`material whose surface has a higher potential than that of the material. In general, an impurity
`layer maybe present on the very surface layer of these materials, andit is desirable to use the
`material after polishing the surface. On the other hand, tin and silicon oxides are also applicable.
`
`fOO28]
`
`A negative electrode using a powderedactive material may includea solid electrolyte. One or
`more solid electrolytes can be selected from the group of materials used for the electrolyte layer
`and used, In consideration of the conductive performance and the thermal stability performance,
`a crystalline sulfide-based inorganic solid electrolyte is desirable, but recently, a sulfide-based
`inorganic solid electrolyte containing no Group 14 element has been proposed. Further, the
`negative electrode using the powdered active material may include a conductive additive. One or
`more conductive assistants can be selected from the graup of conductive assistants that may be
`included in the positive electrode and used.
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`

`{O029|
`
`Whenthe negative clectrode layer is a powder molded body, the negative electrode layer can be
`formed in the same manner as the inorganic solid electrolyte layer described above. Thatis, a
`powder mixture of the negative electrode material may be prepared in a shurry with the solvent
`described above for forming the electrolyte layer. and then formedinto a film by the same
`coating method. Here, the material to be coated is a current collector sheet or a mesh thereon
`according to the embodiment of the present invention. The material to be coated is a current
`collector sheet or a mesh thereon, according to an embodiment of the preserit invention, When
`the negative electrode layer is in the formof a foil, it can be simply arranged so as to be in
`contact with the main surface of the electrolyte layer or can be filled in a mesh according to the
`embodiment of the present invention. The thickness of the negative electrode layeris in the
`range of lio L000 gm, preferably 10 to 100 pm.
`
`{OOSO}
`
`According to one embodiment of the present invention, an intermediate layer which reacts with
`Hthivsnto form a material layer having an electrode potential higher than that of inhiumis
`provided between the negative electrodelayer ane the electrolyte layer. By forming such a
`material layer, the interface between the material layer and the electrolytelayeris stabilized, and
`cycle deterioration (resistancerise) due to lithium being in contact with the electrolyte layer is
`suppressed. As a mechanism for stabilizing the imerface as described above,it is consilered that
`the potential of the material layer derived framthe intermediate layer becomes higher than the
`reduction potential of the electrolyte. However, the present invention is not limited to such a
`theory.
`
`{OOS 1}
`
`The electrode potential of the formed material layer is preferably Q.1 to 1.6 volts. more
`preferably 0.15 to 0.9 volts higher than lithium. [f the electrode potential is higher than 1.6 volis.
`the battery voltage decreases, and a sufficient energy density cannot be obtained, which is not
`desirable. Conversely, if the electrode patential is lower than Q.1 volt, the desired stabilizing
`effect cannot be obtained sufficienthy,
`
`02-03-2020
`
`11
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`

`

`{O032]
`
`Materials for forming the intermediate layer accordingto the present inventioninclude
`aluminum (Al), Li4TiSO'2, Lil-xCoxN, CoO, NiO, FeO, SnS2, Si. MedSi, MedSn, Ag. Bi, Sb, CoSn5,
`In. InSb. . Sn. ane the like, a metal material, an alloy material, or an inorganic material that reacts
`withlithium fo form an intended material layer. Of these, aluminumis preferably used as the
`material for forming the intermediate layer, because aluminumis low in cost, easy to make into a
`foil, and the position of the generated potential is appropriate.
`
`{0033}
`
`The thickness of the intermediate layer is preferably in the range of 0.1 to 500 gm, preferably |
`to 200 pom. Ef the thickness of the intermediate layer is larger than SOO pm,the intermediate
`layer becomes a resistance layer against lithiurn ions and lowers the energy density of the
`battery, which is not desirable. Conversely, if the thickness of the intermediate layeris less than
`O.1 jem, the desired stabilizing effect cannot be obtained sufficiently.
`
`{OO3 4}
`
`1 shows an example of a battery clement havingan intermediate layer according to the
`FIG.
`present invention. Battery element | includes, in arder, first current collector 2, positive
`electrode layer 3, inorganic solid electrolyte layer 4, intermediate layer 5. negative electrade
`layer 6, and second current collector 7, Each of the first current collector 2 and the second
`current collector 7 is provided with an energizing terminal tag (not shown). The intermediate
`layer S reacts with lithium during and / or after the fabrication of the battery element to form a
`material layer having a higher electrode potential than lithium, After the battery element is
`manufactured, before and after the start of charging and discharging are included. Althoughthe
`second