BR102018074749A2 - METHOD FOR PRODUCING A SULFET SOLID STATE BATTERY - Google Patents

Abstract

When depositing an anode mixture containing a silicon-based active material and a solid sulfide electrolyte on a surface of an anode-containing copper current collector in the form of an anode, the solid sulfide electrolyte reacts with the copper together. to the ocv of the silicon-based active material, and copper diffuses from the anode current collector via the solid sulfide electrolyte towards one side of the cathode, causing short circuits of smaller proportions from the cathode and anode. . When the anode mixture is formed, lithium is diffused into the silicon-based active material to reduce the potential. specifically, a sulphide solid state battery is produced via a first doping step of at least one material selected from graphite and lithium-containing lithium titanate to obtain the pre-doped material; a second step of mixing the solid sulfide electrolyte, the silicon-based active material, and the pre-doped material to obtain the anode mixture; and a third step of depositing the anode mixture over the surface of the copper containing anode current collector to obtain the anode.

Description

METHOD FOR PRODUCING A SULFIDE SOLID STATE BATTERY FIELD

The present application describes a method for producing a solid state battery of sulfide.

FUNDAMENTALS

Patent Literatures 1 to 3 describe solid-state sulfide batteries including positive electrodes, negative electrodes, and solid electrolyte layers provided between the positive and negative electrodes. In the Patent Literature 1 art, a mixture of negative electrode including a solid electrolyte of sulfide, a carbon-based active material is deposited over a surface of a negative electrode current collector formed of copper, for obtaining of the negative electrode. In the Patent Literature 2 technique, lithium is supplied from the cathode to the anode by doping an anode active material with lithium before the solid state battery of sulfide displays the use voltage next to the first charge. In the Art of Patent Literature 3, a sulphidation resistant layer is provided along a surface of an anode current collector prior to the deposition of an anode mixture containing a solid electrolyte of sulfide above said surface.

List of References Patent Literature Patent Literature 1: JP 2017-054720 A

Patent Literature 2: JP 2017-147158 A

Patent Literature 3: WO 2014/156638 A1 SUMMARY

Technical Problem [003] The standard electrode potential of a solid-state sulfide battery with respect to lithium is equivalent to the OCV of an active material before being charged and discharged. For example, when an anode mixture containing an active silicon-based material is deposited over a surface of an anode current collector to form an anode, the standard potential of the anode with respect to lithium is approximately 2.8 V .

On the other hand, according to the findings of the inventor of this report, when an anode mixture containing a solid sulfide electrolyte is deposited over a surface of an anode current collector containing copper for the formation of an anode , the solid sulfide state electrolyte reacts with the copper in front of a base potential base of 2.8 V, forming the CuS exhibiting conductivity, etc.

That is, upon deposition of an anode mixture containing a silicon-based active material and a solid sulfide electrolyte over a surface of an anode current collector containing copper for the formation of an anode, the electrolyte of solid sulfide reacts with the copper in front of the OCV of the silicon-based active material, with the copper being diffused from the anode current collector via the solid sulfide electrolyte towards one side of the cathode. The production of a solid state battery of sulfide using such anode may lead to self-discharges induced by short circuits of smaller proportions from a cathode and anode, etc.

Problem Solution [006] The present descriptive report presents as a mechanism for solving the above problem, a method of producing a solid-state sulfide battery, the method comprising: a first step of doping of at least one selected material from the graphite and lithium titanate with lithium, to obtain a pre-doped material, a second step of mixing a solid sulfide electrolyte, an active silicon-based material, and the pre-doped material, for obtaining an anode mixture, and a third step of depositing the anode mixture over a surface of an anode current collector containing copper, to obtain an anode.

In the production method of this report, a ratio (X / Y) of a converted value (X) obtained by converting into capacity a total amount of lithium from which the pre-doped material included in the anode mixture is to be doped, by the total capacity (Y) of the silicon-based active material contained in the anode mixture, preferably, is not less than 0.0005.

In the production method of this report, in the first step, at least said material is preferably doped with lithium by using an electrochemical reaction on a lithium ion battery.

Advantageous Effects [010] In the production method of this report, there is provided the formation of an anode mixture by mixing a predetermined pre-doped material together with a silicon-based active material. In this case, soon after the anode mixture has been formed, the lithium diffuses from the pre-doped material next to the silicon-based active material, which leads to a lowered potential when the anode mixture is employed for an anode . That is, a reaction of a solid electrolyte of sulfide with copper can be eliminated, and diffusion of the copper from an anode current collector via the solid electrolyte of sulfide via the solid electrolyte of sulphide in one side of the cathode and self-discharges caused by short circuits of smaller proportions of a cathode and the anode, etc. can be eliminated. In addition, once existing at the anode for the preservation of its electricity and / or conductivity, the pre-doped material will hardly have negative effects on battery properties.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 comprises a flowchart explaining a method of producing a solid state battery of sulfide 100 S10; Fig.

Figures 2A through 2C are schematic views explaining a flow of the production method of the solid state battery of sulfide 100 S10; and Fig. 3 is a schematic explanatory view of a structure of the solid state battery of sulfide 100.

DETAILED DESCRIPTION OF THE MODES 1. Method of producing the solid state battery of sulfide The flow of a method for the production of a solid state battery of sulfide 100 S10 will be described below with reference to Figures 1 to 3. The method for the production of the solid state battery of sulfide 100 S10 comprises: a first step S1 of doping at least of a material 1 selected from graphite and lithium titanate with lithium to obtain a pre- doped 2; a second step S2 for mixing a solid electrolyte of sulfide 3, a silicon-based active material 4, and the pre-doped material 2, to obtain an anode mixture 5; and a third step S3 for depositing the anode mixture 5 over a surface of an anode current collector 6 containing copper, to obtain an anode 10. 1.1. First step [015] As shown in Fig. 2A, in the first step S1, at least one material 1 selected from the graphite and lithium titanate is doped with lithium, to obtain the pre-doped material 2. 1.1 .1. Material 1 [016] Material 1 consists of at least graphite and lithium titanate (LTO)> both graphite and lithium titanate comprise materials which can store and release lithium, and are known as an active material of anode to a lithium-ion battery. When graphite and LTO are compared, graphite is preferable because the anode potential of the graphite is low, which makes the effect of this report more relevant. This is also due to the greater capacity of graphite. This is also due to the graphite being able to perform well also the conductive additive function. Any type of artificial and natural graphite may consist of material 1. The composition of lithium titanate does not find specific limits, and for example, it may be preferably L140T12. The material 1 format has no specific limits. The shape of a particle consists of the spatial preference for material 1. 1.1.2. Any mode may be employed for doping the lithium material 1 to obtain the pre-doped material 2. Examples thereof include a way of physically mixing material 1 and a source of lithium. lithium for the doping of the lithium material 1, and a method of electrochemical insertion of the lithium next to the material 1. From the viewpoint that the amount of lithium doping in the material 1 can be easily controlled, the material 1 of preference, it comes to be doped with lithium if making use of an electrochemical reaction in a battery of lithium ions. For example, it is preferable to combine material 1, a cathode active material which charges and discharges the lithium ions at a more noble potential than material 1, and some electrolyte incorporating lithium ion conductivity, for the formation of a lithium-ion battery, and doping the material 1 with lithium using a charge reaction on the lithium-ion battery. The lithium ion battery employed in this case may be a battery of a solution system, and may be a solid state battery. Specifically, from the viewpoint that the pre-doped material 2 can be easily separated after doping of the lithium material 1, it is preferred to use a battery of a solution system (battery of a solution system non-aqueous electrolyte or an aqueous battery). That is, one may preferably combine material 1, a cathode active material which loads and discharges the titanium ions at a more noble potential than that of the material 1, an electrolyte incorporating lithium ion conductivity such as LiPF6), and solvent for the dissolution of the electrolyte (water or an organic solvent) to form a lithium ion battery of a solution system, and dope the material 1 with lithium using a reaction of charge the lithium-ion battery. After lithium material 1 has been doped with the use of an electrochemical reaction in the lithium-ion battery, for example, the lithium-ion battery is disassembled for separation of the pre-doped material 2, doped 2 washed and grounded if necessary.

[018] The amount of lithium doping in material 1 has no specific limitations. It is believed that as the amount of lithium doping in the material 1 is increased, the amount of the pre-doped material 2 in the anode mixture 5 described below can be reduced. When material 1 is doped with lithium using a charge reaction in the lithium ion battery, preferably material 1 is doped with lithium until the charged capacity is not less than 10 mAh / g, which , more preferably not less than 50 mAh / g, even more preferably not less than 80 mAh / g, and especially preferably not less than 100 mAh / g. The upper limit has no specific limitations, preferably not greater than 200 mAh / g, more preferably not more than 180 mAh / g, and most preferably not greater than 150 mAh / g. Or, when the lithium-doped material 1 employing a charge reaction on the lithium-ion battery, the battery preferably charges until the SOC is not less than 5%, and more preferably is not less than 8%, and even more preferably not less than 10%. The upper limit has no specific limitations, and is preferably not more than 50%. 1.2. Second Stage [019] As shown in Fig. 2B, in the second step S2, the solid electrolyte of sulfide 3, the silicon-based active material 4, and the pre-doped material 2 are mixed, to obtain the anode mixture 5. 1.2.1. Any sulfide used as a solid electrolyte for a solid-state sulfide battery can be employed as the solid electrolyte of sulfide 3. Examples include U2S-P2S5, Li2S-SiS2, LiI-Li2S-SiS2 , LiI-Li2O-Li2S-P2S5, UI-U2S-P2O5, UI-U3PO4-P2S5, and U2S-P2S5-GeS2. Specifically, a solid sulfide electrolyte containing L12S-P2S5 is most preferably among them. A solid sulfide electrolyte may be used individually, or at least two solid sulfide electrolytes may be mixed to be employed as the solid electrolyte of sulphide 3. In the second step S2, the amount of solid electrolyte of sulphide 3 has no specific limitations, and can be determined appropriately according to the performance of the intended battery. For example, the solid electrolyte content of sulphide 3 is preferably 10% by mass to 60% by mass, if the total of the anode mixture 5 is 100% by mass (the total solid content after drying for removal of the solvent in the case of a humidified mixture. Hereinafter the same.). The lower limit is more preferably not less than 20% by weight, and the upper limit is more preferably not more than 50% by weight. 1.2.2. Silicon-based active material 4 [021] The silicon-based active material 4 must contain only Si as a constituent element, and function as an anode active material in the solid-state sulfide battery. For example, at least Si, a Si alloy, and a silicon oxide may be employed. Specifically, preferably Si or a silicon oxide. The format of the silicon-based active material 4 does not encounter specific limitations, and for example, it is preferably silicon-based active material 4 in the form of a particle. In the second step S2, the amount of silicon-based active material 4 has no specific limitations, and can be determined appropriately according to the performance of the desired battery. For example, the silicon-based active material content 4 is preferably from 30% by weight to 90% by weight if the entire anode mixture 5 is 100% by weight. The lower limit, more preferably, being not less than 50 mass%, and the upper limit being most preferably not more than 80 mass%. 1.2.3. Pre-doped material 2 In the second stage S2, the amount of the pre-doped material 2 has no specific limitations, and can be suitably determined according to the amount of doping in the first step S1, etc. Specifically, in the second stage S2, the mixing ratio of the pre-doped material by the silicon-based active material 4 is preferably determined so that the ratio (X / Y) of the converted value (X) obtained by the conversion in the capacity of the total amount of lithium, where the pre-doped material 2 included in the anode mixture 5 is being doped, the total capacity (Y) of the silicon-based active material 4 contained in the anode mixture 5 is not lower to 0.0005. The ratio (X / Y) most preferably is not less than 0.0008. According to the inventors' findings of the present application, the (X / Y) ratio of not less than 0.0005 may lead to the diffusion of a sufficient amount of lithium together with the silicon-based active material 4, which makes it possible to suppress further self-discharge when forming the solid state battery of sulfide 100.

The expression "converted value (X) obtained by converting the total amount of lithium with which the pre-doped material 2 included in the anode mixture 5 is to be doped" means a value obtained by converting the total amount of lithium lithium which may diffuse in capacity from the pre-doped material 2 next to the silicon-based active material 4 in the anode mixture 5. When material 1 is doped with lithium using a charge reaction on the lithium-ion battery to obtain the pre-doped material 2, the converted value (X) can be obtained from the charged capacity (Ah / g). The expression "Total capacity (Y) of the silicon-based active material 4 contained in the anode mixture 5" consists of the capacity exhibited by the silicon-based active material 4 contained in the anode mixture 5 when encountering under an uncharged state . Specifically, Y may be a chargeability of an active material to be obtained from the initial chargeability obtained when a separately prepared Y-scavenging mixture is charged and discharged into a cell using an electrode opposite Li 1.2.4. Other constituents [024] In the second step S2, preferably the further mixing of a conductive additive in the anode mixture 5 is provided, provided that the problem can be solved. Any skilled person is aware of a conductive additive employed in a solid-state sulfide battery. Examples thereof include a carbon material, such as acetylene black (AB), Ketjen black (KB), a steam-aged carbon fiber (VGCF), carbon nanotubes (CNT), a carbon nanofiber ( CNF), and graphite; and a metallic material, such as nickel, aluminum, and stainless steel. Especially, preference is given to a carbon material. There may be the individual use of a conductive additive, or two or more conductive additives which may be mixed together for use. Any shape, such as powder or fiber, can be employed as the conductive additive shape. In the second step S2, the amount of the conductive additive has no specific limitations and can be determined appropriately according to the intended performance of the battery. For example, the conductive additive content preferably ranges from 0.5% by weight to 20% by weight if the total solid content of the anode mixture 5 is 100% by weight. The lower limit of preference should not be less than 15 by weight, and the upper limit preferably should not exceed 10% by mass.

[025] In the second step S2, preferably the binder is further mixed in the anode mixture 5 as long as the problem can be solved. Any type of agglutinator known to function on a solid-state sulfide battery may be used. For example, at least one of those selected from styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), acrylonitrile-butadiene rubber (ABR), butadiene rubber (BR), polyvinylidene fluoride ( PVDF), polytetrafluoroethylene (PTFE), etc. In the second step S2, the amount of agglutinator has no specific limitations, and can be determined appropriately according to the performance of the battery to be obtained. For example, the agglutinator content preferably ranges from 1% by weight to 30% by weight, if the entire solid content of the anode mixture 5 is 100% by weight. The lower limit, more preferably, being not less than 2% by mass, and the upper limit, more preferably not greater than 15% by mass.

[026] In the second step S2, a solid electrolyte, other than the solid electrolyte of sulfide 3, may be further mixed in the anode mixture 5 as long as the problem can be solved. Examples thereof include a solid oxide electrolyte, such as lithium lanthanum zirconate, LiPON, Li 1 + XAlXGe 2 -o x (PO 4) 3, Li-SiO-based glass, and Li-Al based glass -ONLY.

[027] In the second step S2, an anode active material, other than the silicon-based active material 4, may be further mixed into the anode mixture 5, provided that the problem can be solved. Examples thereof include a carbon material, such as graphite and hard carbon, various oxides, such as lithium titanate, and lithium metal or a lithium alloy. 1.2.5. In the second step S2, the way of mixing the solid electrolyte of sulphide 3, the silicon-based active material 4, and the pre-doped material 2 for the formation of the anode mixture 5 has no limitations specific. The second step S2 may be performed employing a known mixing mechanism. The mixture in the second step S2 may be a humidified mixture using solvent, or dry mixing without the solvent (mixing granular materials together). From the point of view that the materials can be mixed more evenly, and that the lithium can diffuse more suitably from the pre-doped material 2 next to the silicon-based active material 4, the humidified mixture employing the solvent comes to be preferable. Specifically, preference may be given to mixing the solid electrolyte of sulfide 3, the silicon-based active material 4, and the pre-doped material 2 together with the solvent, to obtain the mixture of anode 5 in the form of a or a slurry. The solvent employed in this case has no specific limitations. Preferred examples thereof include butyl butyrate and N-methylpyrrolidone (NMP). 1.3. Third stage [029] As shown in Fig. 2C, in the third step S3, the anode mixture 5 is deposited over the surface of the anode current collector 6 containing the copper, to obtain the anode 10. 1.3.1. Anode current collector 6 containing copper [030] The anode current collector 6 only has to contain copper. Examples thereof include the metal blade and a metal mesh containing the copper or a copper alloy. Or, the anode current collector 6 may be one whose base material is galvanized with copper or a copper alloy, or next to a base material where the deposition of copper or a copper alloy occurs. Specifically, the metal sheet formed of copper (copper sheet) is preferred. The thickness of the anode current collector 6 has no specific limitations, for example, preferably 0.1 to 1 mm, and more preferably 1 to 100 Âμm. 1.3.2. Method of deposition [031] The manner of depositing the anode mixture 5 over the surface of the anode current collector 6 has no specific restrictions. The anode mixture 5 may be applied to the surface of the anode current collector 6 rm with a humidification process, and to dry and optionally press-mold the manifold 6, adjacent to the layer of the anode mixture 5 over the surface of the anode current collector 6. It may also be press-formed 5 in conjunction with the anode current collector 6 in a drying process, to form the anode mixture 5 over the surface of the collector anode stream 6. In the case of a humidification process, preferably the anode mixture 5 is dispersed over the solvent or the like, into a paste or a semi-fluid mixture, as previously described. Pressure molding in the third step S3 is believed to lead to improved contact between the solid electrolyte of sulfide 3, the silicon active material 4, and the pre-doped material 2, in the anode mixture 5, which makes it possible the diffusion of the lithium more evenly from the pre-doped material 2 together with the silicon-based active material 4, exerting a more relevant effect.

The layer thickness of the anode mixture 5 is to be deposited over the surface of the anode current collector 6 via the third step S3 (thickness after drying, removing the solvent in the case of a humidification process) has specific limitations, and is preferably, for example, from 0.1 to 1 mm, and more preferably from 1 to 100 .mu.m. Or, the layer thickness of the anode mixture 5 is preferably determined so that the capacity of the anode 10 is greater than that of the cathode 20.

[033] According to the foregoing description, the anode 10 of the solid state battery of sulfide 100 can be produced via the steps of S1 to S3. At the anode 10, a layer of an anode mixture differentiated from the anode mixture 5 may further be provided over a garnish of the anode mixture layer 5, appearing on the side opposite the anode current collector 6 (gasket adjacent a cathode side if the anode 10 is used in the battery). Examples thereof include layers containing only an active material, as long as it is not a silicon-based active material (such as a carbon-based active material) in the function of the anode active material. 1.4. Addition [034] As shown in Fig. 3, the solid state battery of sulfide 100 includes the cathode 20 and a layer of solid electrolyte 30 in addition to the anode 10 produced according to steps S1 to S3. The methods of producing the cathode 20 and the solid electrolyte layer 30 are commercially known. That is, the solid state battery of sulfide 100 can be produced by the same conventional method, with the exception that the method includes the production method S10. 1.4.1. Cathode 20 [035] Although the structure of the cathode 20 in the solid state battery of sulphide 100 is obvious to the person skilled in the art, the following is an example. The cathode 20 generally includes an active cathode material, and a cathode blend layer 22 containing, as optional constituents, a solid electrolyte, binder, a conductive additive, and other additives (thickeners, etc.). Preferably, there is included a cathode current collector 21 which is in contact with the cathode mixing layer 22.

The cathode current collector 21 may be formed of metal foil, a metal mesh, or the like. The metal blade is especially preferred. Examples of metal which may constitute the cathode current collector include stainless steel, nickel, chromium, gold, platinum, aluminum, iron, titanium, zinc, etc. The cathode current collector 21 may also be a metal blade where, or whose base material is galvanized with such metal or where the base material of such type of metal is to be deposited.

[037] Any known type for the cathode active material function for a sulfide solid state battery can be employed as the active cathode material contained in the cathode blend layer 22. Among such known active materials, a material exhibiting a higher charge and discharge potential than that silicon based active material 4, as a function of the cathode active material. Examples thereof include an oxide-containing lithium, such as lithium cobaltate, lithium nickelate, Li (Ni, Mn, Co) O 2 (Li 1 + aNi 1/3 Mn 1/3 Co 1/3 O 2), lithium manganate, lithium titanate, and a lithium metal phosphate (LiMPO 4 where M is at least one element selected from Fe, Mn, Co and Ni). An active cathode material may be employed individually, or two or more cathode active materials which may be mixed may be used. The active cathode material may have a coating layer of lithium niobate, lithium titanate, lithium phosphate, or the like over its surface. The format of the active cathode material does not encounter specific limitations, and is preferably the active cathode material, for example in the form of a particle or a thin film. The content of the cathode active material in the cathode blend layer has no specific limitations, and may be equivalent to the amount of active cathode material contained in a cathode mixture layer of a solid state sulfide battery.

[038] Any solid electrolyte known to work with a solid state battery of sulphide may be employed. Preferred examples thereof include a solid sulfide electrolyte, according to the foregoing description. A solid inorganic electrolyte, other than a solid sulfide electrolyte, may be incorporated in addition to the solid sulfide electrolyte, provided a desired effect is obtained. The same elements employed for the conductive addition and binder may also be used in the function of the anode 10 as well. A solid electrolyte (conductive additive, binder) may be used individually, or two or more solid electrolytes (conductive additives, binders) may be mixed for use. The solid electrolyte and the conductive additive formats do not find particular limitations, for example preferably in the form of a particle. The contents of the solid electrolyte, the conductive additive, and the binder in the cathode blend layer do not encounter any particular limitations, and those relating to a solid electrolyte, a conductive additive, and binder in a cathode blend layer of a solid-state battery of conventional sulfide.

The cathode 20 incorporating the structure described above can be easily produced by going through the steps, such as the placement of the active cathode material, and the solid electrolyte, the binder, and the conductive additive, which are optionally included, together with the solvent, being kneaded to obtain a semi-fluid electrode composition, and subsequently applying this electrode composition to a surface of the cathode current collector, and drying the surface. The cathode can be produced, not only through this humidification process, but also through a drying process. When the cathode mixture layer in the form of a sheet is formed by on the surface of the cathode current collector, as described above, the thickness of the cathode blend layer is, for example, preferably from 0.1 to 1 mm, and most preferably 1 to 100 Âμm. 1.4.2. While the structure of the solid electrolyte layer 30 in the solid state battery of sulfide 100 becomes a truism to the person skilled in the art, the following is an example. The solid electrolyte layer 30 contains a solid electrolyte, and optionally, a binder. For example, a solid sulfide electrolyte, according to the foregoing description, is preferably employed as the solid electrolyte. For example, a solid inorganic electrolyte, other than a solid sulfide electrolyte, may be contained in addition to the solid sulfide electrolyte, provided that a desired effect can be achieved. The binder, identical to that described above, may be suitably selected for use. The contents of the constituents in the solid electrolyte layer 30 may be the same as in the conventional manner. The shape of the solid electrolyte layer 30 may also be the same as the conventional one. Specifically, the layer of solid electrolyte 30 in the form of a sheet is preferred. The solid electrolyte layer 30 in the form of a sheet can be easily produced by going through the steps, such as placing the solid electrolyte, and optionally the binder together with the solvent, by kneading the parts to obtain a semi-fluid electrolyte composition , this electrolyte composition being subsequently applied to a surface of a base material or together with (a) surface (s) of the cathode mixture layer and / or anode mixing layer 30, by drying the s) surface (s). In this case, the thickness of the solid electrolyte layer 30, for example, is preferably 0.1 to 300 Âμm, and most preferably 0.1 Âμm to 100 Âμm. 1.4.3. Other members [041] It goes without saying that the solid state battery of sulfide 100 may include the necessary terminals, the battery casing, etc., in addition to the anode 10, the cathode 20, and the solid electrolyte layer 30. These members are commercially known, and the detailed descriptions thereof are omitted. 1.5. Solid-state sulfide battery 100 [042] For example, the solid-state sulfide battery 100 produced via production method S10 of this disclosure has a structural aspect as follows: ie the solid state battery of sulfide 100 includes the anode 10, the cathode 20, and the solid electrolyte layer 30 provided between the anode 10 and the cathode 20, wherein the anode 10 includes a layer formed of the anode current collector 6 containing the copper, and the mixture of the anode 5 provided over the surface of the anode current collector 6, the anode mixture 5 contains the solid electrolyte of sulfide 3, the silicon-based active material 4, and the pre-doped material 2, the material being pre- -dopate 2 obtained by the doping of the material 1, which is selected from at least from graphite and lithium titanate (preferably material 1 consists of graphite) with lithium. The limb structures are described above, and the detailed description thereof is omitted presently.

[043] According to the above description, in the production method S1 of this report, the predetermined pre-doped material 2 is prepared in the first stage S1, and the pre-doped material 2 is mixed together with the active material a silicon base 4 producing the anode mixture 5 in the second step S2. In this case, soon after the anode mixture is made, the lithium diffuses from the pre-doped material 2 next to the silicon-based active material 4, which leads to a lowered standard potential with respect to lithium if the mixture 5 is used for the anode 10. That is, the reaction of the solid electrolyte of sulfide 3 with copper (copper in the anode current collector 6) can be eliminated, the diffusion of the copper from the anode current collector 6 via the solid electrolyte of sulphide 3 in the direction next to the cathode 20 can be eliminated, and self-discharges caused by minor short-circuits of the cathode 20 and the anode 10 etc. can be disposed of in the solid state battery of sulfide. Furthermore, since there is preservation of its electronic characteristics and / or ion conductivity at the anode 10, the pre-doped material 2 hardly has the negative effects on the properties of the solid state battery of sulfide 100. 2. Advantageous addition in the production method of this descriptive report. [044] The same effect seems to be obtained by the doping of a silicon-based active material used as an anode active material already containing lithium using an electrochemical reaction in a battery of ions of lithium before an anode mixture is made. However, it is believed that this is not feasible from the point of view of costs; in this case, for example, a much larger amount of an active material has to be doped than in the case of production method S10.

The problem of CuS formation seems to be solved by employing an anode current collector which is to be formed from a metal other than copper. However, in this case, some battery properties, including cycle characteristics, etc., may deteriorate. 3. Market Evidence [046] For example, it can be confirmed by the following way whether a solid-state sulfide battery is to be produced by the production method of this descriptive report or not. That is, it can be confirmed whether a solid-state sulfide battery is being produced by the production method of this report or not, by means of a solid-state sulfide battery, by analyzing part of an anode active material, which does not contact a cathode or an anode, or by checking the balance of cathode and anode potentials in a three electrode cell. Or, when a pre-doped material is to be obtained by using an electrochemical reaction on a battery of a solution system, an SEI is formed by on a surface of the pre-doped material. Therefore, it can be confirmed whether a solid-state battery of sulfide is produced by the production method of this report or not, as well as by confirming whether the graphite or lithium titanate contained in an anode exhibits an SEI above the its surface or not. Examples of compounds that may constitute an SEI include LiF, LiCO3, and a phosphate ester. Examples of how to confirm the presence or absence of the compounds that may constitute an SEI include elemental analysis using TEM-EELS, ICP, and EPS, mass spectrometry using TOF-SIMS, and analysis of the combination thereof. For example, if this modality is performed or can not be determined by the confirmation that an element, such as fluorine, which does not contain raw materials of a solid electrolyte, is only contained in an SEI which is formed by a surface of a pre-doped material. examples <Example 1> 1. Producing the solid state battery of sulfide 1.1. Producing the cathode active material The LiNi1 / 3Mn1 / 3Co1 / 302 particles (average particle size (D50): 6 pm) were prepared. LiNbO3 was coated on the surfaces of the particles by the sol-gel process. Specifically, a solution of ethanol that dissolved the equimolar UOC2H5 and Nb (OC2H5) 5 was coated onto the surfaces of the particles under atmospheric pressure employing a drum fluid coating machine (SFP-01 manufactured by Powrex Corporation). The processing time was adjusted such that the thickness of this coating was 5 nm. The coated particles were then heated thermally at 350 ° C under atmospheric pressure for 1 hour to obtain an active cathode material. 1.2. The cathode active material obtained, and a solid sulfide electrolyte (Lil-L 2 O-L 2 S-P 2 S 5, average particle size (D 50): 2.5 μm) were weighed so that their mass ratios were of cathode active material: solid sulfide electrolyte = 75:25. In addition, 100 parts by mass of active cathode material, 4 parts by mass of a PVDF based binder (manufactured by Kureha Corporation) and 6 parts by mass of acetylene black in the form of a conductive additive. They were prepared in butyl butyrate so that the solid content was 70% by mass, being kneaded with a stirrer, to obtain a cathode paste. The 15 mm thick aluminum foil was coated with the cathode slurry obtained by a vane coating method using an applicator such that the weight of the slurry was 30 mg / cm 2, with the slurry being dried 120 ° C for 3 minutes to obtain a cathode including a layer of cathode mixture over the aluminum foil. 1.3. Producing the solid electrolyte layer In a heptane solvent, 95 parts by weight of the solid electrolyte of sulfide were weighed as above and 5 parts by weight of butylene rubber as a binder were prepared so that the solid content came to be 70% by mass. The parts were agitated via an ultrasonic dispersion device (UH-50 manufactured by SMT Corporation) for 2 minutes to obtain a solid electrolyte slurry. A base material (aluminum foil) was coated with the solid electrolyte slurry obtained in the same manner as in the case of the cathode slurry, so that the weight of the slurry was 60 mg / cm 2, the base material being dried with air, and subsequently dried at 100 ° C for 30 minutes to obtain the base material including a layer of solid electrolyte. 1.4. Producing the anode 1.4.1. In the water for ion exchange, 99.7 parts by mass of refined particles of natural graphite (average particle size (D50): 15 μm) and 0.3 parts by mass of carboxymethyl cellulose, prepared so that the solid content became 60% by mass, being kneaded by means of a planetary mixer to obtain the pulp. The obtained slurry was uniformly applied to the copper foil according to a vane coating method, the copper foil being dried at 120 ° C for 5 minutes to obtain an electrode. The obtained electrode was punched to have a diameter of 16 mm, incorporating a cell in disk employing metal Li as an opposite electrode, a PE separator incorporating a thickness of 20 μm in the form of a separator, and a non-aqueous electrolytic solution ( mixed solvent of EC and DEC (EC: DEC = 1: 1) dissolved in mol / kg of LiPFe in concentration) as an electrolyte solution. This cell on disk has been loaded by a loading and unloading device. The loaded capacity was adjusted to be 100 mAh / kg by the total weight of the graphite contained in the disc cell. After loading, the disk cell was disassembled before an argon atmosphere and the electrode was removed. After the EMC electrode was washed, the graphite was separated from the copper foil by means of a spatula to obtain a pre-doped material. 1.4.2. Production of the anode mixture and deposition of the anode mixture over the copper foil The solid sulfide electrolyte, according to the foregoing description, were refined the silicon refined particles (average particle size (D50): 6 pm), and the pre-doped material to give the solid electrolyte mass ratio of sulfide by refined silicon particles: pre-doped material = 45: 53.4: 1.6 (silicon-based active material : pre-doped material = 97: 3). In addition, they were weighed to 100 parts by mass of the refined silicon particles, 6 parts by mass of a PVDF based binder (manufactured by Kureha Corporation) and 6 parts by mass of acetylene black as a conductive additive. They were prepared in the butyl butyrate so that the solid content was 70% by mass, being kneaded with a stirrer, to obtain a pasty anode mixture. The copper foil of thickness of 15 Âμm was uniformly coated with the slurry obtained according to a vane coating method using an applicator, the copper foil being dried at 120Â ° C for 3 minutes to obtain an anode including an anode blend layer over the copper blade. 1.5. Deposition of the cathode, solid electrolyte layer, and anode [052] The solid electrolyte layer described above was punctured to have an area of 1 cm2, being pressed at 1 ton / cm2. The cathode was connected next to a liner of the pressed solid electrolyte layer (trim along the opposite side of the base material), being pressed at 1 ton / cm2. The base material was separated from the assembly. The anode was connected to the separate trim, being pressed at 6 ton / cm2, to obtain a laminate formed by: cathode / solid electrolyte / anode layer. The obtained laminate was hermetically sealed in an aluminum laminated film incorporating terminals, to obtain a solid state battery of sulfide to be evaluated. The battery specifications obtained are shown in Table 1 below. 2. Self-discharge test on a solid-state sulfide battery [053] As described above, there is a case where the copper blade reaction, consisting of an anode current collector with a solid electrolyte of sulfide, leads to the formation of CuS incorporating high conductivity, Cu diffuses from the anode current collector towards one side of the cathode, minor short-circuits being caused between a cathode and an anode, and the voltage of a battery solid state of sulfide is lowered spontaneously. In order to evaluate this condition, the solid state battery of sulfide was subjected to the self-discharge test by the following procedures. That is, first, after loading of the solid-state sulfide battery (charging conditions: 4.4 V ccv, current rate 2 mA, cut-off current 0.1 mA), the battery was allowed to remain in a constant temperature oven at 25 ° C for 25 hours, the voltage (ÁV) being evaluated during the stay. The results are shown in Table 1 below. 3. Evaluation of cycle characteristics [054] It is expected that when a carbon-based active material is used in conjunction with an active silicon-based material, the rate of expansion in the entire anode active material is facilitated and the characteristics of the cycle of a solid-state sulfide battery are improved in charge / discharge, compared to the case where only a silicon-based active material is used as an anode active material. In order to confirm this effect, the cycling test was conducted under the following conditions. The calculation was performed using a discharge capacity after the one hundred and fiftieth cycle next to the first discharge capacity as a capacity retention (5). This cycling test was conducted so that the battery was delimited by means of a restriction template containing a load cell so that a pressure of 5 MPa was evenly applied to guaranty the anode and the cathode. The result is shown in Table 1 below. (Conditions for the cycle test) load: 4.4V cccv, current rating 10 mA, cut-off current 0.5 mA discharge: 3.0 V dc, current rating 10 mA temperature: 25 ° C 2 to 4 and Comparative Example 1>

[055] A solid state battery of sulfide subjected to self-discharge testing and evaluation of cycle characteristics was developed in the same manner as in Example 1, except that the mixing ratio of the anode active material by the pre-doped material was changed as shown in Table 1 below. The specifications of the battery, and the results of the self-discharge tests and cycle characteristics are presented in Table 1 below. <Example 5>

[056] A solid state battery of sulfide subjected to self-discharge tests and evaluation of cycle characteristics was developed in the same manner as in Example 1, except that the capacity charged during the formation of the pre-doped material was changed to 150 mAh / g. The specifications of the battery, and the results of the self-discharge tests and evaluation of the cycle characteristics are presented in Table 1 below. <Example 6>

[057] A solid state sulfide battery subjected to self-discharge testing and evaluation of cycle characteristics was developed in the same manner as in Example 1, except that the material used as the pre-doped material was changed from graphite to the lithium titanate (mean particle size of (D 50): 2 pm) was used to obtain the pre-doped material by the following procedures. The specifications of the battery, and the results of the self-discharge tests and evaluation of the cycle characteristics are presented in Table 1 below.

[058] In NMP, 92 parts by weight of lithium titanate, 3 parts by mass of a PVDF-based binder, and 5 parts by mass of acetylene black were weighed and prepared, so that the solids content being 70% by mass, being kneaded by means of a planetary mixer to obtain the paste. The obtained paste was applied to the copper blade according to a vane coating method, the copper blade being dried to obtain an electrode in the same manner as in Example 1. A disk cell was formed by employing the electrode obtained in the same manner as in Example 1. The cell on disk was charged in the same manner as in Example 5 (charged capacity of 150 mAh / g). After disassembling the cell to disk and effecting its separation from the copper foil, in the same manner as in Example 1, the separated powder was dispersed next to the NMP in an approximate volume 10 times greater than the original powder, being subjected to centrifugation three times for the removal of the PVDF-based binder, etc. fixed together with lithium titanate. Refined particles obtained after centrifugation were used as the pre-doped material. <Example 7>

A solid state battery of sulfide was subjected to self-discharge tests and evaluation of cycle characteristics in the same manner as in Example 1, except that the silicon was exchanged for the silicon oxide (average particle size of (D50): 5 pm), and the weight of the pulp obtained at the anode was altered. The specifications of the battery, and the results of the self-discharge test and evaluation of the cycle characteristics are presented in Table 1 below. <Example 8>

A solid state battery of sulfide subjected to self-discharge testing and evaluation of cycle characteristics was developed in the same manner as in Example 1, except that the capacity charged during the formation of the pre-doped material was changed to 10 mAh / g, and the mixing ratio of the anode active material by the pre-doped material was changed as given in Table 1 below. The specifications of the battery, and the results of the self-discharge tests and evaluation of the cycle characteristics are presented in Table 1 below. <Comparative Example 2>

[061] A solid state battery of sulfide subjected to self-discharge tests and evaluation of cycle characteristics was developed in the same manner as in Comparative Example 1, except that the stainless steel blade of the same thickness was used as the collector of anode current rather than the copper blade. The specifications of the battery, and the results of the self-discharge tests and evaluation of the cycle characteristics are presented in Table 1 below. <Reference Example 1>

[062] A solid state battery of sulfide was developed undergoing self-discharge tests and evaluation of cycle characteristics in the same manner as in Example 1, except for the use of a stainless steel blade of the same thickness as that of anode current collector replacing the copper blade. The technical specifications of the battery, and the results of the self-discharge tests and evaluation of the cycle characteristics are shown in Table 1 below.

Table 1 [063] As evident from the results presented in Table 1, the containment of the pre-doped material in the anode mixture led to a significant reduction of self-discharge. The pre-doped material is believed to have promoted the reduction of the initial anode potential of the solid-state sulfide battery, suppressing the reaction of the copper foil and the solid sulfide electrolyte. While there was no pre-doped material contained in the specifically limited anode mixture and a certain effect was exerted, if not with only a slight amount of the pre-doped material present in the anode mixture, from the Examples of 1 to 8, it can be stated that the ratio (X / Y) of a converted value (X) obtained by converting into capacity the total amount of lithium with which the pre-doped material included in the anode mixture is doped, by the total capacity (Y) of the silicon-based active material contained in the anode mixture, is preferably not less than 0.0005. Specifically, if X / Y is not less than 0.0008, when the self-discharge is suppressed to approximately 0.18, V, this represents the limit of the elimination effect of the self-discharge. Or, from Examples 1 to 8, an anode active material is preferably not less than 70 mass% and less than 100 mass%, and a pre-doped material is preferably larger than 0% by mass and not more than 30% by mass if the total of the anode active material and the pre-doped material is 100% by mass. In view, for example, of an anode capacity, etc. an anode active material may be preferably not less than 90 mass%, still more preferably not less than 93 mass%, and specifically, preferably not less than 96 mass%, and a pre-doped material may be more preferably not more than 10% by weight, even more preferably not more than 7% by weight, and specifically, preferably not more than 4% by weight.

[064] As is evident from the results of Examples 1 to 8 and Comparative Example 1, when the copper foil was used as the anode current collector, containing the pre-doped material in the anode mixture there were improvements in characteristics of the solid-state battery cycle of sulfide.

[065] Furthermore, as is evident from the results of Examples 6 and 7, the same effect was obtained even if the anode active material and / or the pre-doped material had been / were changed.

[066] Changing a material from an anode current collector to a metal other than copper (such as stainless steel) as given in Comparative Example 2 and Reference Example 1 also makes it possible to avoid the formation of CuS, and reduce self-discharge. However, in this case, some of the properties of a battery, other than self-discharge deteriorate. For example, as shown in Comparative Example 2, the characteristics of the battery cycle deteriorate. As is evident from the results of Comparative Example 2 and Reference Example 1, when using the stainless steel blade as the anode current collector, it was difficult to improve the cycle characteristics even if there was the presence of the pre- in the anode mixture. This is believed to be due to the fact that the stainless steel blade is coarser than the copper blade, and therefore being hard to accompany the expansion / contraction of an anode active material at the loading / unloading.

[067] From the above description it may be said that when an anode mixture layer containing an active silicon-based material and a solid electrolyte of sulphide is provided on a surface of an anode current collector , it is advantageous to use the copper-containing anode current collector, and then to contain a predetermined pre-doped material in an anode mixture, to eliminate CuS formation, as compared to employing the collector of anode stream formed of material other than copper to prevent formation of CuS.

Industrial Applicability [068] A solid state battery of sulfide produced according to the production method of this descriptive report can be used in a wide variety of power supplies such as a small power supply for portable devices and a large internal power supply.

List of Reference Elements 10 anode 1 material consisting of graphite and / or lithium titanate 2 pre-doped material 3 solid electrolyte of sulphide 4 silicon-based active material 5 anode mixture 6 anode current collector 20 cathode 21 collector cathode current layer 22 cathode mix layer 30 solid electrolyte layer 100 solid state sulfide battery

Claims (3)

A method for producing a solid-state sulfide battery CHARACTERIZED in that the method comprises: a first step of doping of at least one material selected from graphite and lithium titanate with lithium to obtain a pre-filled material -doped; a second step of mixing a solid sulfide electrolyte, an active silicon-based material, and the pre-doped material, to obtain an anode mixture; and a third step of depositing the anode mixture on a surface of an anode current collector containing copper, to obtain an anode. A method according to claim 1, characterized in that a ratio (X / Y) of a converted value (X) obtained by the conversion of a total amount of lithium, with which the pre-doped material included in the mixture of anode is being doped, in capacity, by the total capacity (Y) of the silicon-based active material contained in the anode mixture is not less than 0.0005. A method according to claim 1 or 2, CHARACTERIZED by the fact that in the first step, said at least one material is doped with lithium using an electrochemical reaction on a lithium ion battery.