JP2015216077A - Method for manufacturing all-solid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a sulfide-based all-solid battery, by which the short circuit between current collectors can be suppressed further in comparison to a conventional manner, without the need for an additional member.SOLUTION: A method for manufacturing an all-solid battery comprises the steps of: (A)preparing, in a first atmosphere, an electrode body including a positive electrode layer, a negative electrode layer, a solid electrolytic layer disposed between the positive and negative electrode layers and including a sulfide-based solid electrolyte, a positive electrode current collector disposed in contact with the positive electrode layer, and a negative electrode current collector disposed in contact with the negative electrode layer. At least one of the positive and negative electrode current collectors is composed of a copper current collector, and the positive and negative electrode current collectors each have an uncoated portion; (B)putting the electrode body in a container which can be sealed hermetically; (C)making an atmosphere in the container a second atmosphere having a dew point temperature higher than the first atmosphere; and (D)sealing the container hermetically. In the all-solid battery, the sulfide-based solid electrolyte is reacted with moisture in the second atmosphere to generate hydrogen sulfide; and the hydrogen sulfide is reacted with the uncoated portion of the copper current collector to sulfuret at least a part of the surface of the uncoated portion of the copper current collector, thereby producing copper sulfide.

Description

  The present invention relates to a method for manufacturing an all-solid battery.

  In recent years, a secondary battery has become an indispensable component as a power source for personal computers, video cameras, mobile phones, and the like, or as a power source for automobiles and power storage.

  Among secondary batteries, a lithium ion secondary battery has a feature that it has a higher capacity density than other secondary batteries and can operate at a high voltage. Therefore, it is used in information-related equipment and communication equipment as secondary batteries that are easy to reduce in size and weight. In recent years, high-output and high-capacity lithium-ion secondary batteries for electric vehicles and hybrid vehicles as low-pollution vehicles have been used. Development is underway.

  A lithium ion secondary battery or a lithium secondary battery includes a positive electrode layer and a negative electrode layer, and an electrolyte containing a lithium salt disposed between the positive electrode layer and the negative electrode layer, and the electrolyte is constituted by a non-aqueous liquid or solid. . When a non-aqueous liquid electrolyte is used for the electrolyte, the electrolyte solution penetrates into the positive electrode layer, so that an interface between the positive electrode active material constituting the positive electrode layer and the electrolyte is easily formed, and performance is easily improved. . However, since widely used electrolytes are flammable, it is necessary to install a system for ensuring safety such as attachment of a safety device that suppresses temperature rise at the time of short circuit and prevention of short circuit. In contrast, an all-solid battery in which the liquid electrolyte is changed to a solid electrolyte to make the battery all solid does not use a flammable organic solvent in the battery, so the safety device can be simplified, and manufacturing costs and productivity can be reduced. It is considered excellent and is being developed.

  As an all-solid battery, an all-solid battery using a sulfide-based solid electrolyte having high lithium ion conductivity has been studied (Patent Document 1).

JP 2011-154902 A

  Conventionally, when producing an all-solid-state battery as described in Patent Document 1, a current collector has a complicated structure such as bundling or bending a current collector. In order to suppress a short circuit due to contact with the body, the uncovered portion of the current collector is subjected to insulation treatment.

  As a conventional insulating treatment method, there is a method of disposing an insulating member such as attaching an insulating tape to an uncoated portion of a current collector or performing resin coating. However, when the insulating tape is used, the position where the insulating tape is applied may be shifted, and when the resin coating is used, the coating position may be shifted. Thus, when the arrangement position of the insulating member is deviated, the uncovered portion of the current collector is exposed, and there is a possibility that a short circuit occurs. Moreover, in order to suppress a short circuit, another member was required and there existed the subject which cost and a man-hour increase.

  Therefore, there is a demand for a method for producing a sulfide-based all-solid-state battery that can suppress a short circuit between current collectors as compared with the related art without requiring a separate member.

The present invention is an all-solid battery manufacturing method,
(A) In a first atmosphere, a positive electrode layer, a negative electrode layer, a solid electrolyte layer including a sulfide-based solid electrolyte disposed between the positive electrode layer and the negative electrode layer, a positive electrode current collector disposed in contact with the positive electrode layer, And an electrode body including a negative electrode current collector disposed in contact with the negative electrode layer,
At least one of the positive electrode current collector and the negative electrode current collector is a copper current collector, and the positive electrode current collector and the negative electrode current collector have an uncoated portion,
(B) placing the electrode body in a sealable container;
(C) The process which makes the inside of a container the 2nd atmosphere which has a dew point temperature higher than a 1st atmosphere, and (D) The process of sealing a container,
Including
Surface of the uncovered portion of the copper current collector by reacting the sulfide-based solid electrolyte with moisture in the second atmosphere to generate hydrogen sulfide, and reacting the hydrogen sulfide with the uncovered portion of the copper current collector At least a portion of
It is a manufacturing method of an all-solid-state battery.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the sulfide type all-solid-state battery which can suppress the short circuit between collectors conventionally can be provided, without requiring another member.

FIG. 1 is a schematic cross-sectional view of an all-solid battery in which a plurality of electrode bodies are stacked. FIG. 2 is a schematic top view of an electrode body in which uncovered portions of the positive electrode current collector and the negative electrode current collector are drawn out. FIG. 3 is a schematic top view of an electrode body having an uncoated portion to which a tab lead is connected. FIG. 4 is a schematic cross-sectional view of an all-solid battery in which a plurality of electrode bodies are stacked. FIG. 5 is a schematic top view of an electrode body having an uncoated portion in which a portion where a tab lead is to be attached is covered with a cover that is resistant to hydrogen sulfide. FIG. 6 is a schematic perspective view of a laminate in which a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a negative electrode current collector are laminated. FIG. 7 is a schematic perspective view of the electrode body after the laminated body is press-molded. FIG. 8 is a schematic cross-sectional view showing an aspect in which a negative electrode current collector drawn out of the electrode body is molded using a molded plate. FIG. 9 is a schematic perspective view of an electrode body in which a tab lead is attached to a current collector. FIG. 10 is a schematic view showing an aspect in which the electrode body is disposed in the laminate. FIG. 11 shows a mode in which after the laminate is heat-sealed leaving the position where the uncovered portion can be held, the gas in the second atmosphere is injected from the place where the heat-sealing is left, and the atmosphere inside the laminate is changed to the second atmosphere. FIG. FIG. 12 is a schematic view of an electrode body sealed in a laminate. FIG. 13 is a schematic cross-sectional view of the surface of a copper current collector. FIG. 14 is a schematic cross-sectional view of an uneven portion on the surface of a copper current collector. FIG. 15 is a schematic top view of an electrode body having a copper sulfide generation portion on a part of the surface of the uncovered portion of the copper current collector. FIG. 16 is a schematic perspective view of an uncovered portion of the copper current collector shown in FIG. FIG. 17 is a schematic cross-sectional view of the copper current collector of FIG. FIG. 18 is a graph showing the relationship between the generated thickness (one side) of copper sulfide and the volume resistivity of the copper current collector. FIG. 19 is a graph showing the relationship between the generated thickness (one side) of copper sulfide and the surface resistivity of the copper current collector.

  The present invention is directed to a method for manufacturing an all-solid battery, and the all-solid battery includes one or more electrode bodies. FIG. 1 is a schematic cross-sectional view of an all-solid battery 100 in which a plurality of electrode bodies 10 are stacked. As shown in FIG. 1, one or more electrode bodies 10 including a positive electrode layer 1, a negative electrode layer 2, a solid electrolyte layer 3, a positive electrode current collector 4, and a negative electrode current collector 5 are laminated to produce an all-solid battery 100. can do. The positive electrode current collector 4 and the negative electrode current collector 5 are drawn out of the electrode body 10. FIG. 1 illustrates a state where the negative electrode current collector 5 is drawn out of the electrode body 10. Similarly, the positive electrode current collector 4 is drawn out of the electrode body 10, but is omitted in FIG.

  In FIG. 1, of the positive electrode current collector 4 and the negative electrode current collector 5 drawn from the electrode body 10, a portion where the surface is not covered and the surface of the current collector is exposed is an uncoated portion. It is called 6. As described above, conventionally, in order to prevent a short circuit between the positive electrode current collector 4 and the negative electrode current collector 5, an uncoated portion such as applying an insulating tape to the uncoated portion 6 or applying a resin coating, etc. Although the method of arranging the insulating member on the surface of 6 is used, there is a possibility that a short circuit may still occur due to the displacement of the arrangement position of the insulating member. There was a problem that man-hours increased.

  The present inventor has intensively studied to solve such a problem, and is a method for producing an all-solid battery including a sulfide-based solid electrolyte, wherein a copper current collector is provided on at least one of a positive electrode current collector and a negative electrode current collector. The hydrogen sulfide gas is generated by utilizing the reaction between the sulfide-based solid electrolyte and the moisture in the atmosphere, and the uncovered portion of the copper current collector is reacted with the hydrogen sulfide gas. A manufacturing method has been found that includes sulfiding at least a portion of the surface to produce copper sulfide. Copper sulfide has a higher resistance value than copper, and when this is generated on the surface of a copper current collector, short-circuiting can be prevented when it comes into contact with the other current collector.

  According to the present invention, it is not necessary to arrange another member for preventing a short circuit such as an insulating tape or a resin coating. It becomes possible to suppress. Moreover, since this invention does not require short-circuit prevention members, such as an insulating tape and resin coating, cost and a man-hour can be reduced rather than before.

  In the present invention, only the surface layer of the copper current collector is an insulating improvement layer, and the inner layer of the copper current collector is less affected by hydrogen sulfide and can substantially maintain the conductivity of the copper current collector. Therefore, the insulation property of the surface of the copper current collector can be improved without greatly affecting the performance of the all solid state battery.

  For example, when using a copper current collector as the negative electrode current collector, the uncovered portion of the copper current collector is made of copper sulfide, so that even if the negative electrode current collector is in contact with the positive electrode current collector, a short circuit is caused. It can suppress more than before. Further, when a copper current collector is used as the negative electrode current collector, even if the negative electrode current collector is in contact with the positive electrode layer, a short circuit can be suppressed as compared with the conventional case.

  Similarly, when a copper current collector is used as the positive electrode current collector, the short circuit can be suppressed more than ever even if the positive electrode current collector is in contact with the negative electrode current collector or the negative electrode layer.

  Hydrogen sulfide is generated and supplied by the reaction between the sulfide solid electrolyte contained in the all-solid battery and the moisture in the atmosphere around the electrode body. By the reaction between the generated hydrogen sulfide and copper in the uncovered portion, copper sulfide can be generated on at least a part of the surface of the uncovered portion, and an insulating improvement layer can be formed. Since the generated hydrogen sulfide is a gas, it can be supplied substantially uniformly to the surface of the uncoated portion of the copper current collector by diffusion. Moreover, since the generated hydrogen sulfide is generated in the vicinity of the solid electrolyte layer, that is, in the vicinity of the uncoated portion of the current collector, it can be easily supplied to the uncoated portion. Hereinafter, steps included in the manufacturing method according to the present invention will be described.

Process (A)
The manufacturing method according to the present invention includes a step (A) of producing an electrode body. In the step (A), in the first atmosphere, a positive electrode layer, a negative electrode layer, a solid electrolyte layer including a sulfide-based solid electrolyte disposed between the positive electrode layer and the negative electrode layer, a positive electrode disposed in contact with the positive electrode layer An electrode body including a current collector and a negative electrode current collector disposed in contact with the negative electrode layer is manufactured.

  The first atmosphere only needs to have a dew point at which the sulfide-based solid electrolyte does not substantially deteriorate during the production of the electrode body, preferably −60 ° C. or less, more preferably −70 ° C. or less, and further preferably −80 ° C. It has the following dew point temperature.

The electrode body produced in the step (A) has an outer dimension of an arbitrary area such as ¹ to 3000 cm ² and 10 to 1000 cm ² , and 20 to 2500 μm and 50 to 50 to, for example, depending on required battery characteristics. It can have any thickness such as 300 μm.

  The electrode body can be manufactured by a method similar to a conventionally used method, and includes a positive electrode layer, a negative electrode layer, a solid electrolyte layer including a sulfide-based solid electrolyte disposed between the positive electrode layer and the negative electrode layer, a positive electrode As long as the positive electrode current collector disposed in contact with the layer and the negative electrode current collector disposed in contact with the negative electrode layer are included, the structure can have any structure that can function as an all-solid battery. FIG. 1 is a schematic cross-sectional view showing an example of the electrode body 10.

  As illustrated in FIG. 1, the electrode body 10 can include a positive electrode layer 1, a negative electrode layer 2, and a solid electrolyte layer 3 disposed therebetween. A positive electrode current collector 4 is electrically connected to the positive electrode layer 1, and a negative electrode current collector 5 is electrically connected to the negative electrode layer 2.

The solid electrolyte layer 3 contains a sulfide-based solid electrolyte. As a material for the sulfide-based solid electrolyte, a material that can be used as a sulfide-based solid electrolyte for an all-solid battery can be used. For example, Li ₂ S—SiS ₂ , LiI—Li ₂ S—SiS ₂ , LiI—Li ₂ S—P ₂ S ₅ , LiI—Li ₂ S—B ₂ S ₃ , Li ₃ PO ₄ —Li ₂ S—Si ₂ S, Li ₃ PO ₄ —Li ₂ S—SiS ₂ , LiPO ₄ —Li ₂ S—SiS, LiI—Li ₂ S—P ₂ O ₅ , LiI—Li ₃ PO ₄ —P ₂ S ₅ , or Li ₂ A sulfide-based solid electrolyte such as S—P ₂ S ₅ can be used. Moreover, glass ceramics obtained by heat-treating an amorphous sulfide-based solid electrolyte can also be used as the solid electrolyte.

Each of the positive electrode layer 1 and the negative electrode layer 2 contains an electrode active material, and a material that can be used as an electrode active material of an all-solid battery can be used as the electrode active material. Examples of the active material include lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ ), LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ , Li _{1 + x Mn 2-xy M y} O 4 (M is, Al, Mg, Co, Fe, Ni, and one or more metal elements selected from Zn) different element substituted Li-Mn spinel composition represented by, Transition metal oxidation such as lithium titanate (Li _x TiO _y ), lithium metal phosphate (LiMPO ₄ , M is Fe, Mn, Co, or Ni), vanadium oxide (V ₂ O ₅ ), and molybdenum oxide (MoO ₃ ) things, titanium sulfide (TiS _2), carbon materials such as graphite and hard carbon, lithium-cobalt nitride (LiCoN), lithium silicon oxide _{(Li x Si y O z)} , lithium metal (L ), Lithium alloy (LiM, M is, Sn, Si, Al, Ge, Sb, or P), lithium storage intermetallic compound (Mg _x M or NySb, M is Sn, Ge or Sb, N is an In,,, Cu, or Mn) and the like, and derivatives thereof.

  In the present invention, there is no clear distinction between the positive electrode active material and the negative electrode active material, and the two types of charge / discharge potentials are compared. Can be used as a negative electrode to form a battery having an arbitrary voltage.

  At least one of the positive electrode layer 1 and the negative electrode layer 2 may contain a sulfide-based solid electrolyte. When the sulfide-based solid electrolyte is included in at least one of the positive electrode layer 1 and the negative electrode layer 2, the materials mentioned as the sulfide-based solid electrolyte contained in the solid electrolyte layer can be used, and preferably included in the solid electrolyte layer. The same sulfide-based solid electrolyte can be used. The mixing ratio of the electrode active material and the solid electrolyte is not particularly limited. For example, the electrode active material: solid electrolyte volume ratio can be 20:80 to 90:10, or 40:60 to 70:30. . When the sulfide-based solid electrolyte is contained in one or both of the positive electrode layer 1 and the negative electrode layer 2, moisture in the second atmosphere and the sulfide-based solid electrolyte in the bulb layer are reacted to form hydrogen sulfide. Can be generated.

In the case where the positive electrode layer 1 contains a sulfide-based solid electrolyte, the high resistance layer is hardly formed at the interface between the positive electrode active material and the sulfide-based solid electrolyte, thereby making it easy to prevent battery resistance from increasing. Therefore, the positive electrode active material is preferably coated with an ion conductive oxide. As the lithium ion conductive oxide covering the positive electrode active material, for example, the general formula LixAOy (A is B, C, Al, Si, P, S, Ti, Zr, Nb, Mo, Ta or W, x and y are positive numbers)). Specifically, Li ₃ BO ₃ , Li _B O ₂ , Li ₂ CO ₃ , LiAlO ₂ , Li ₄ SiO ₄ , Li ₂ SiO ₃ , Li ₃ PO ₄ , Li ₂ SO ₄ , Li ₂ TiO ₃ , Li ₄ Examples thereof include Ti ₅ O ₁₂ , Li ₂ Ti ₂ O ₅ , Li ₂ ZrO ₃ , LiNbO ₃ , Li ₂ MoO ₄ , Li ₂ WO _{4 and the} like. The lithium ion conductive oxide may be a complex oxide.

As the composite oxide covering the positive electrode active material, any combination of the above lithium ion conductive oxides can be employed. For example, Li ₄ SiO ₄ —Li ₃ BO ₃ , Li ₄ SiO ₄ —Li ₃ PO ₄ etc. can be mentioned.

  When the surface of the positive electrode active material is coated with an ion conductive oxide, the ion conductive oxide only needs to cover at least part of the positive electrode active material, and may cover the entire surface of the positive electrode active material. . The thickness of the ion conductive oxide that coats the positive electrode active material is, for example, preferably from 0.1 nm to 100 nm, and more preferably from 1 nm to 20 nm. The thickness of the ion conductive oxide can be measured using, for example, a transmission electron microscope (TEM).

  Each of the positive electrode layer 1 and the negative electrode layer 2 may contain a binder. The material of the binder is not particularly limited, and polytetrafluoroethylene, polybutadiene rubber, hydrogenated butylene rubber, styrene butadiene rubber, polysulfide rubber, polyvinyl fluoride, polyvinylidene fluoride, and the like can be used.

  Each of the positive electrode layer 1 and the negative electrode layer 2 may contain conductive aid particles as desired. The conductive aid particles are not particularly limited, and graphite, carbon black and the like can be used.

  At least one of the positive electrode current collector 4 and the negative electrode current collector 5 is a copper current collector, and when a current collector other than copper is used as the other positive electrode current collector or negative electrode current collector, the material is conductive. And having a function as a positive electrode current collector or a negative electrode current collector can be used. Preferably, the negative electrode current collector is a copper current collector, and more preferably, both the positive electrode current collector and the negative electrode current collector are copper current collectors.

  Examples of the material of the positive electrode current collector 4 include SUS, aluminum, copper, nickel, iron, titanium, and carbon. Furthermore, examples of the shape of the positive electrode current collector 4 include a foil shape, a plate shape, and a mesh shape. Among these, a foil shape is preferable.

  Examples of the material for the negative electrode current collector 5 include SUS, copper, nickel, and carbon. Furthermore, examples of the shape of the negative electrode current collector 5 include a foil shape, a plate shape, and a mesh shape. Among these, a foil shape is preferable.

  The thickness of the positive electrode current collector 4 and the negative electrode current collector 5 is not particularly limited, and can be, for example, about 5 to 500 μm.

  The manufacturing method of an all-solid battery is not particularly limited, and a method similar to a general manufacturing method of an all-solid battery can be used. As an example of a method for producing an all-solid battery, a positive electrode layer, a solid electrolyte layer, and a negative electrode layer are stacked, pressed as desired to produce an electrode body, and this electrode body is housed inside a battery case. A method of caulking the battery case can be given as desired.

  The positive electrode layer and the negative electrode layer can be prepared by forming on a substrate. Forming the positive electrode layer and the negative electrode layer on the substrate can be performed using a slurry coating process, a blast method, an aerosol deposition method, a cold spray method, a sputtering method, a vapor phase growth method, or a thermal spray method. The positive electrode layer and the negative electrode layer can be obtained by a simple process and a slurry coating process, which is preferably used.

  The substrate is not particularly limited as long as the positive electrode layer and the negative electrode layer can be formed thereon, and is a metal current collector that can be used as a current collector, a film-like flexible group. A material, a hard substrate, or the like can be used. For example, a substrate such as a metal foil, a metal plate, or a polyethylene terephthalate (PET) film can be used.

  The positive electrode layer and the negative electrode layer are preferably formed using a current collector as a base material. After forming an electrode layer on a base material, you may press.

  When forming an electrode layer on a substrate other than a metal foil used as a current collector, the electrode layer is peeled off from the substrate and the electrode layer and the current collector are laminated, or the electrode layer is transferred to the current collector. May be. You may further press after lamination | stacking or transcription | transfer.

  Examples of the slurry coating process include a dam type slurry coater, a doctor blade method, a gravure transfer method, and a reverse roll coater. By such a slurry coating process, a slurry containing an active material can be coated and dried on a substrate to obtain an electrode layer.

  The slurry containing an active material can be prepared by a conventionally known method by mixing an active material and a solvent, and preferably a solid electrolyte, a conductive aid, and a binder. The prepared slurry can be applied and dried on a substrate.

  The solvent used for the preparation of the slurry is not particularly limited as long as it does not adversely affect the performance of the active material. Examples thereof include hydrocarbon organic solvents such as heptane, toluene, and hexane. A hydrocarbon-based organic solvent having a low content is used.

For example, LiNi _1/3 Co _1/3 Mn _1/3 O ₂ as a positive electrode active material, VGCF as a conductive additive, Li ₂ S—P ₂ S ₅ as a sulfide-based solid electrolyte, polyvinylidene fluoride as a binder, and What mixed heptane as a solvent in the ratio generally used can be apply | coated to the aluminum foil as a positive electrode electrical power collector, and what dried can be used as a positive electrode coating film. The aluminum foil current collector has an uncoated portion for tab lead bonding.

For example, graphite mixed as a negative electrode active material, Li ₂ S—P ₂ S ₅ as a sulfide-based solid electrolyte, polyvinylidene fluoride as a binder, and heptane as a solvent are mixed in a proportion generally used. The negative electrode coating film can be formed by coating on a copper foil as an electric body and drying it. The copper foil current collector has an uncoated portion for tab lead bonding.

  The solid electrolyte layer includes a sulfide-based solid electrolyte, and may include a binder or the like as desired. Examples of the binder material that can be included in the solid electrolyte layer include the same materials that can be included in the electrode layer, and are not particularly limited.

  The solvent used for the preparation of the slurry containing the solid electrolyte is not particularly limited as long as it does not adversely affect the performance of the solid electrolyte, and examples thereof include hydrocarbon-based organic solvents such as heptane, toluene, and hexane, preferably dehydration. Hydrocarbon organic solvents that have been treated to reduce the water content are used.

For example, 38.28 g of Li ₂ S (Nippon Chemical Industry) and 61.72 g of P ₂ S ₅ (Aldrich) are weighed as a sulfide-based solid electrolyte, mixed for 5 minutes in an agate mortar, and 200 g of heptane as a solvent. And then using a planetary ball mill, mechanical milling at 500 rpm for 20 hours, heating at 110 ° C. for 1 hour to remove heptane, weighing 900 mg, and containing 5 wt% butadiene rubber (BR) as a binder A mixture of 180 mg of heptane solution and 1515 mg of heptane is applied to an aluminum foil, dried, and the aluminum foil is peeled off to form a solid electrolyte coating film.

  The all solid state battery produced according to the present invention can be a primary battery or a secondary battery, preferably a secondary battery. This is because it can be repeatedly charged and discharged and is useful, for example, as a vehicle-mounted battery. Examples of the shape of the all solid state battery include a coin type, a laminate type, a cylindrical type, and a square type.

  The uncoated portion 6 is a portion where the surfaces of the positive electrode current collector 4 and the negative electrode current collector 5 are exposed, and a tab lead can be joined thereto. FIG. 2 is a schematic top view of the electrode body 10 from which the uncovered portions 6 of the positive electrode current collector 4 and the negative electrode current collector 5 are drawn, and FIG. 3 has the uncovered portions 6 to which the tab leads 7 are connected. The upper surface schematic diagram of the electrode body 10 is shown. The uncoated portion 6 is a part of the positive electrode current collector 4 and the negative electrode current collector 5 (hereinafter also referred to as a current collector), has a shape protruding from the electrode body 10, and is joined to the tab lead 7. be able to. An insulating film may be disposed on the open surface of the tab lead 7 (the surface not in contact with the uncoated portion 6) to prevent a short circuit. When the electrode body 10 is put into an exterior body such as a laminate, the tab lead can be pulled out of the exterior body.

  As shown in FIG. 3, the tab lead 7 may be attached to the uncoated portion 6, and then copper sulfide may be generated on the surface of the uncovered portion 6 of the copper current collector that is not coated with the tab lead 7.

  Before connecting the uncoated portion 6 to the tab lead 7, copper sulfide may be formed on at least a part of the surface of the uncoated portion 6. In this case, after producing copper sulfide on the copper current collector, in order to electrically connect the copper current collector and the tab lead, the copper sulfide is polished by polishing or the like from the surface of the copper current collector where the tab lead is to be attached. Can be removed.

  As shown in FIG. 5, the tab lead attachment planned portion is covered with a cover 8 that is resistant to hydrogen sulfide so as not to react with hydrogen sulfide, and copper sulfide is generated on the surface of the remaining uncoated portion 6. May be. In this case, it is possible to remove the cover 8 after generating copper sulfide on the copper current collector and attach the tab lead so as to completely cover the portion covered with the cover 8.

  As shown in FIG. 1, when the current collector is disposed between the positive electrode layer 1 or the negative electrode layer 2 in the electrode body 10, a portion drawn out of the electrode body 10 becomes an uncovered portion. As shown in FIG. 4, when the current collector is disposed on the uppermost layer or the lowermost layer of the electrode body 10, the released surface (the surface not in contact with the positive electrode layer or the negative electrode layer) and the electrode body 10. The part drawn out to the outside becomes an uncoated part.

  When the current collector is disposed on the uppermost layer or the lowermost layer of the electrode body 10, in steps (B) to (D), not only the part of the current collector drawn out of the electrode body 10 but also the released surface. Copper sulfide may be formed on at least a part of the surface of the uncoated part of the metal, or coated with a material resistant to hydrogen sulfide so that the exposed surface of the current collector is not exposed. From this, copper sulfide may be generated in the uncoated portion. For example, a sheet resistant to hydrogen sulfide, such as polyethylene, may be disposed and adhered to the released surface of the current collector, or the electrode body may be disposed inside a laminate resistant to hydrogen sulfide. The inner surface of the laminate may be brought into close contact with the released surface of the current collector.

  As shown in FIGS. 6 and 7, the positive electrode layer, the negative electrode layer, the positive electrode layer, and the negative electrode layer are disposed in contact with the solid electrolyte layer, the positive electrode current collector disposed in contact with the positive electrode layer, and the negative electrode layer. An electrode body can be obtained by laminating a negative electrode current collector and forming an interface between layers by press molding. 6 is a schematic perspective view of a laminate in which a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a negative electrode current collector are laminated. FIG. 7 is an electrode body after the laminate is press-molded. 10.

  As shown in FIG. 8, the negative electrode current collector 5 drawn out of the electrode body 10 can be molded using a molding plate 11 such as a bakelite plate so as to follow the shape of the end face of the electrode body 10. FIG. 8 is a schematic cross-sectional view showing a mode in which the negative electrode current collector 5 drawn out of the electrode body 10 using the molded plate 11 is molded, and the positive electrode current collector 4 is omitted. The electric body can be molded in the same manner as the negative electrode current collector.

  As shown in FIG. 9, a copper tab lead can be attached to the molded copper current collector, and a tab lead made of the same material as the current collector, such as a copper tab lead or an aluminum tab lead, can be attached to the other current collector. The tab lead can be attached to the current collector by a conventionally used method such as ultrasonic bonding. The attachment of the tab lead to the current collector may be performed after the steps (B) to (D).

Process (B)-(D)
In the present invention, the step (B) of putting the electrode body in a sealable container, the step (C) of making the inside of the container a second atmosphere having a dew point temperature higher than the first atmosphere, and the step of sealing the container (D )including. The order of steps (B) and (C) can be varied as desired, and may be performed simultaneously or sequentially. For example, the electrode body may be placed in a sealable container, and the atmosphere in the container may be changed to the second atmosphere, or after the atmosphere in the container is changed to the second atmosphere, the electrode body may be put in the container.

  The second atmosphere is an atmosphere having a dew point temperature higher than that of the first atmosphere, preferably −50 ° C. or higher, more preferably −30 ° C. or higher, further preferably −10 ° C. or higher, and even more preferably 10 ° C. or higher. Has dew point temperature. In the dew point temperature range, the reaction between the sulfide-based solid electrolyte and moisture can be further promoted.

  The moisture concentration of the second atmosphere is preferably a concentration range corresponding to the above dew point temperature range. Table 1 shows the relationship between the dew point temperature and the moisture concentration in the gas phase (in the air).

  The upper limit of the dew point temperature of the second atmosphere is not particularly limited, but can be, for example, 20 ° C. or less.

  Similarly to the first atmosphere, the second atmosphere is preferably an air atmosphere or an inert gas atmosphere, and more preferably an inert gas atmosphere. Examples of the inert gas include argon or nitrogen.

In steps (B) to (D), the electrode body placed in the container is reacted with moisture in the second atmosphere to generate hydrogen sulfide, and at least a part of the surface of the uncovered portion of the copper current collector is formed. It can be sulfided to produce copper sulfide. The resulting copper sulfide can be a compound in which Cu and S are in any ratio, preferably CuS, Cu ₂ S, or a combination thereof.

  The exposure time to the second atmosphere is not limited, but can be determined according to the dew point temperature, the configuration of the electrode body and the container, the desired copper sulfide formation thickness, etc., for example, the lower limit is 5 minutes or more, It can be 1 hour or more, or 10 hours or more, and the upper limit can be 1000 hours or less, 500 hours or less, or 100 hours or less. After sealing, the amount of moisture in the second atmosphere is consumed by the reaction and gradually decreases. When an electrode body is put in the laminate and the inside of the laminate is sealed in a second atmosphere, the all-solid battery can be completed as it is without taking out the electrode body.

  In the step (D), the container is sealed at the same time as or after the exposure of the electrode body to the second atmosphere, but is preferably sealed at the same time or immediately after the exposure. By sealing the container, the generated hydrogen sulfide gas can be efficiently supplied to the surface of the uncoated portion of the current collector. In addition, since the volume of the second atmosphere is determined by sealing the container, the amount of hydrogen sulfide generated and the amount of copper sulfide generated can be estimated from the amount of water in the second atmosphere.

  The container has a shape in which an electrode body can be put therein, and is preferably made of a material resistant to hydrogen sulfide, such as aluminum, stainless steel, polyethylene, polystyrene, It is made of a material containing epoxy resin, polycarbonate resin, acrylic resin, vinyl chloride or the like.

  The container is preferably a glow box, a desiccator or a laminate, more preferably a laminate, and further preferably an aluminum laminate whose inner surface is covered with a heat-sealable resin. Any two or all of a glow box, a desiccator, and a laminate may be used in combination.

  When the container is a glow box, for example, an electrode body is produced in a glow box having a first atmosphere, and the inside of the glow box is replaced with a second atmosphere having a dew point temperature higher than that of the first atmosphere. Can be sealed. In another method, for example, an electrode body is produced in a first glow box having a first atmosphere, and the electrode body is moved to a second glow box having a second atmosphere having a dew point temperature higher than that of the first atmosphere. The second glow box can be sealed.

  When the container is a desiccator, for example, an electrode body is produced in a glow box having a first atmosphere, the electrode body is placed in the desiccator, and the interior of the desiccator is replaced with a second atmosphere having a dew point temperature higher than that of the first atmosphere. The desiccator can be sealed.

  When the container is a laminate, for example, an electrode body is produced in a glow box having a first atmosphere, the electrode body is placed in the laminate, and a second dew point temperature higher than that in the first atmosphere is placed in the glow box. By substituting with the atmosphere, the atmosphere inside the laminate can also be replaced with the second atmosphere, and the laminate can be sealed. When the container is a laminate, another method is to produce an electrode body in a first glow box having a first atmosphere, place the electrode body in the laminate, and place the electrode body in the laminate from the first atmosphere. The laminate can be hermetically sealed by moving to a second glow box having a second atmosphere having a high dew point temperature and the atmosphere inside the laminate also being a second atmosphere. When the container is a laminate, another method is to produce an electrode body in a glow box having a first atmosphere, place the electrode body in the laminate, and inject a gas in the second atmosphere into the laminate using a hose or the like. Thus, the laminate can be sealed by setting the atmosphere inside the laminate to the second atmosphere.

  When the container is a laminate, as one embodiment, for example, as shown in FIG. 10, after the electrode body 10 is arranged in the laminate 30, as shown in FIG. After heat-sealing the laminate 30 leaving a position where the heat seals, the gas in the second atmosphere is injected from the place where the heat seal is left, and the atmosphere inside the laminate 30 is changed to the second atmosphere, as shown in FIG. The laminate 30 can be sealed. By arranging a heat-fusible resin layer on the surface of the tab lead 7, when the laminate 30 is sealed, the heat-fusible resin layer on the surface of the tab lead 7 is heat-sealed so that the periphery of the tab lead 7 is also sealed. can do. The laminate 30 can be a conventionally used laminate such as one using two laminates as shown in FIG. 10 or one using a single laminate folded.

  While using a glow box or a desiccator as a container, an electrode body may be placed in the laminate. For example, an electrode body is produced in a glow box having a first atmosphere, the electrode body is placed in a laminate, and the inside of the glow box is replaced with a second atmosphere having a dew point temperature higher than that of the first atmosphere. And the laminate may be sealed after the treatment for improving the insulation of the surface of the non-current-collecting portion. In this case, the moisture to be reacted with the copper current collector can be supplied not only from the moisture in the atmosphere contained in the laminate but also from the moisture in the atmosphere contained in the glow box.

  When the laminate is used as a container, the laminate can be sealed after copper sulfide is formed on the uncovered portion of the current collector, or the laminate can be sealed immediately after the atmosphere in the laminate is changed to the second atmosphere. . When the laminate is sealed after the copper sulfide is generated in the uncovered portion of the current collector, the gas in the second atmosphere can be continuously sent into the laminate using a hose or the like. When the laminate is sealed immediately after the atmosphere in the laminate is changed to the second atmosphere, the generated hydrogen sulfide can be kept in the laminate, and the generated hydrogen sulfide can be efficiently used for producing copper sulfide. Moreover, when unreacted hydrogen sulfide exists after producing | generating copper sulfide in the uncoated part of an electrical power collector, according to the conventionally performed method, unreacted hydrogen sulfide can be processed.

(Change in volume resistivity of copper current collector when copper sulfide is produced)
In the following manner, the volume resistivity change of the copper current collector was measured when at least part of the surface of the copper current collector was sulfided to produce copper sulfide.

A copper foil having a length of 50 mm, a width of 80 mm, and a thickness of 10 μm was prepared as a copper current collector, and this copper foil was subjected to a hydrogen sulfide gas corrosion test under conditions of 100% H ₂ S and 50 ° C. for 24 hours. The volume resistivity of the copper foil was measured before and after the test. Table 2 shows the measurement results of the volume resistivity before and after the copper foil test.

  The volume resistivity was changed 14 times by the hydrogen sulfide gas corrosion test.

(Lower limit of copper sulfide formation thickness)
The lower limit value of the copper sulfide production thickness is preferably such that copper is not substantially exposed on the surface of the copper current collector. On the surface of the copper current collector, copper sulfide is formed so that the copper is not substantially exposed, so that the copper current collector is a conductive part other than the copper current collector, for example, the other current collector. Even if it contacts with the electrode layer, it becomes difficult to short-circuit.

  As shown in FIG. 13, the surface of the copper current collector 9 has minute irregularities having a surface roughness Rz. FIG. 13 is a schematic cross-sectional view of the surface of the copper current collector 9. The surface roughness Rz is the ten-point average roughness, and only the reference length was extracted from the roughness curve in the direction of the average line, and measured in the direction of the vertical magnification from the average line of the extracted portion. Calculate the sum of the average absolute value of the elevation (Yp) from the highest peak to the fifth and the average absolute value of the lowest elevation (Yv) from the lowest valley to the fifth. This is expressed in micrometers (μm). The surface roughness Rz can be confirmed by a scanning electron microscope (SEM).

  The lower limit of the thickness of the copper sulfide so that copper is not substantially exposed on the surface of the copper current collector is preferably the same as Rz on one side of the copper current collector from the viewpoint of substantially eliminating the portion not covered with copper sulfide. That is, it is preferably the same thickness as twice Rz on both sides of the copper current collector.

  In the vicinity of the surface of the copper current collector, copper sulfide is generated, and copper and copper sulfide having different resistance values are mixed. In the present application, the generated thickness of copper sulfide is the equivalent thickness of a region in which copper sulfide existing together with copper in the copper current collector is collected only on the surface side of the copper current collector. It is the thickness 13 from the reference position 12 of the conversion region 19 where only the copper sulfides shown in 13 and 14 are collected. FIG. 14 is a schematic cross-sectional view of an uneven portion on the surface of a copper current collector. As shown in FIGS. 13 and 14, the reference position 12 is the average position of the altitude (Yp) of the highest peak from the highest peak in the definition of Rz on the surface of the copper current collector. The total thickness of the copper current collector is the thickness between the reference positions 12 on both sides of the copper current collector. The formed thickness of copper sulfide can be measured using WDX, EDX, or the like for the cross section of the sulfided copper current collector. Further, by knowing in advance the correlation between the sulfurization treatment conditions and the copper sulfide production thickness, the production conditions of the copper sulfide can be changed by appropriately controlling the treatment conditions during production.

  The surface roughness Rz of the copper current collector can vary depending on the manufacturer and the product number of the copper current collector, but the Rz of the copper foil generally used as the current collector material is generally 0.4 μm to 1 μm. When a copper current collector with Rz of 0.4 μm is used, the lower limit value of the copper sulfide formation thickness on one side can be set to 0.4 μm or more.

(Upper limit value of copper sulfide formation thickness)
The upper limit value of the copper sulfide formation thickness is preferably such that the resistivity in the length direction 15 of the uncovered portion 6 of the copper current collector shown in FIG. 15 is compared with the resistivity before sulfidation treatment (when untreated). The thickness is doubled. This is the minimum electrical conductivity required for securing the performance required for actual use as a vehicle-mounted cell.

  The thickness of the copper current collector 15 in the longitudinal direction 15 is 20 mm × 20 mm × 10 μm, as shown in FIG. 16, with a thickness that doubles the resistivity before the sulfurization treatment (when not treated). The calculation was performed as follows using a model in which copper sulfide was formed on the surface of a portion 18 having a length of 1 mm, a width of 20 mm, and a thickness of 10 μm. The model shown in FIG. 16 is a schematic perspective view of the copper current collector shown in FIG. 15 extracted from the uncoated portion 6 of 20 mm × 20 mm × 10 μm, and the copper sulfide generation portion 18 is disposed inside the electrode body 10. Exists at a position in contact with the current collector.

  FIG. 17 is a schematic cross-sectional view of the copper current collector of FIG. In the copper sulfide generation portion 18 of FIG. 17, since a region in which copper and copper sulfide having different resistance values are mixed is formed, the resistance of this portion is represented as a parallel circuit, and the combined resistance of this portion is expressed as Ra. And The copper current collector has a region where only copper is present inside the copper current collector, and the resistance of this portion is Rb. The inner portion of the copper current collector is only copper (resistance Rb), and the resistance value of this portion varies depending on the copper sulfide formation thickness.

The volume resistivity of copper sulfide is 2.7 × 10 ⁻⁷ (Ω · m), which is the volume resistivity after the hydrogen sulfide gas corrosion test of the copper foil. .67 × 10 ⁻⁸ (Ω · m) was used.

  The relationship between the thickness of copper sulfide (one side) and the volume resistivity of the copper current collector was calculated under the condition that both sides of a 10 μm thick copper current collector were sulfided to produce copper sulfide of the same thickness on both sides. . The calculation results are shown in FIG.

  As shown in FIG. 18, the volume resistivity of the copper current collector increases as the ratio of the copper sulfide production thickness increases. That is, as the ratio of the copper sulfide generation thickness increases, the conductivity in the direction 15 in FIG. 17 decreases and it becomes difficult to collect current from the electrode body. When the copper sulfide generation thickness is 27% on one side with respect to the entire thickness of the copper current collector, that is, when the thickness is 54% on both sides, the volume of the copper current collector on which copper sulfide is generated on the surface The resistivity is about twice the volume resistivity before copper sulfide formation. Accordingly, the upper limit of the copper sulfide production thickness is preferably 27% of the total thickness of the copper current collector on one side and 54% of the total thickness of the copper current collector on both sides.

(Short-circuit suppression effect)
In the model shown in FIG. 17, as the thickness of the copper sulfide generation portion 18 increases, the resistance in the thickness direction 16 of the copper current collector increases, and a short circuit between the copper current collector and the other current collector hardly occurs. can do.

  The thickness of copper sulfide generated under the condition that both sides of a copper current collector having a thickness of 10 μm and a surface roughness Rz of 0.4 μm are sulfided, and both surfaces of the copper current collector are uniformly sulfided to produce copper sulfide. The relationship of the surface resistivity of the copper current collector with respect to (one side) was calculated. The calculation results are shown in FIG.

  As shown in FIG. 19, the surface resistivity of the copper current collector increases as the copper sulfide generation thickness of the surface portion of the copper current collector increases.

From the graph of FIG. 19, the surface resistivity of the copper current collector when the surface is untreated (copper) is 8.35 × 10 ⁻⁹ Ω. When the copper sulfide formation thickness on one side of the copper current collector is 0.4 μm (0.8 μm on both sides), which is the same as the surface roughness Rz, the surface resistivity of the copper current collector is 1.85 × 10 ⁻⁸ ( Ω). It can be seen that when copper sulfide having the same thickness as the surface roughness Rz is generated, the surface resistivity is approximately doubled compared to the initial untreated surface.

Further, from the graph of FIG. 19, when the copper sulfide generation thickness on one side of the copper current collector is 2.7 μm (5.4 μm on both sides), which is 27% of the total thickness of the copper current collector, The surface resistivity of the body is 6.74 × 10 ⁻⁸ (Ω). When the surface resistivity of the copper current collector when not treated (copper) is 8.35 × 10 ⁻⁹ Ω, and the copper sulfide thickness is 27% of the total thickness of the copper current collector on one side. Is about 8 times the surface resistivity compared to that of copper alone.

  In this way, by producing copper sulfide on the surface of the copper current collector, the increase in volume resistivity is reduced, the surface resistivity is increased, and the other current collector and the active material layer are short-circuited. Can be suppressed.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

DESCRIPTION OF SYMBOLS 100 All-solid-state battery 10 Electrode body 1 Positive electrode layer 2 Negative electrode layer 3 Solid electrolyte layer 4 Positive electrode current collector 5 Negative electrode current collector 6 Uncoated part 7 Tab lead 8 Corrosion-resistant cover 9 Copper current collector 11 Molded plate 12 Copper sulfide Thickness reference position 13 Thickness of copper sulfide 15 Length direction of current collector made of copper 16 Thickness direction of current collector made of copper 18 Copper sulfide produced portion 19 Conversion region in which only copper sulfide was collected 30 Laminate

Claims (6)

A method of manufacturing an all-solid battery,
(A) In a first atmosphere, a positive electrode layer, a negative electrode layer, a solid electrolyte layer including a sulfide-based solid electrolyte disposed between the positive electrode layer and the negative electrode layer, and a positive electrode collector disposed in contact with the positive electrode layer A step of producing an electrode body including a current collector and a negative electrode current collector disposed in contact with the negative electrode layer,
At least one of the positive electrode current collector and the negative electrode current collector is a copper current collector, and the positive electrode current collector and the negative electrode current collector have an uncoated portion;
(B) placing the electrode body in a sealable container;
(C) a step of making the inside of the container a second atmosphere having a dew point temperature higher than the first atmosphere; and (D) a step of sealing the container,
Including
The sulfide solid electrolyte is reacted with moisture in the second atmosphere to generate hydrogen sulfide, and the hydrogen sulfide and the uncovered portion of the copper current collector are reacted to produce the copper current collector. Sulfiding at least a part of the surface of the uncoated portion of copper to produce copper sulfide,
Manufacturing method of all solid state battery.   The manufacturing method according to claim 1, wherein the first atmosphere has a dew point temperature of −60 ° C. or lower.   The manufacturing method according to claim 1, wherein the second atmosphere has a dew point temperature of −50 ° C. or higher.   The manufacturing method as described in any one of Claims 1-3 whose said container is a glow box, a desiccator, or a laminate.   The manufacturing method as described in any one of Claims 1-4 whose production | generation thickness of the said copper sulfide in the single side | surface of the said copper electrical power collector is the same as or more than the surface roughness Rz of the said copper electrical power collector.   The manufacturing method as described in any one of Claims 1-5 whose production | generation thickness of the said copper sulfide in the single side | surface of the said copper electrical power collector is 27% or less of the whole thickness of the said copper electrical power collector.

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