JP7127235B2 - Solid electrolyte sheet and manufacturing method thereof, all-solid battery, and manufacturing method of all-solid battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to a solid electrolyte sheet and its manufacturing method, an all-solid battery, and a manufacturing method of an all-solid battery.

In recent years, the rapid spread of information and telecommunications equipment, and the development of electric and hybrid vehicles is being actively promoted. It is For example, it is known that a lithium ion battery has at least three layers of a positive electrode, a separator, and a negative electrode, and is formed in a structure in which these layers are covered with an electrolyte. Organic solvents, which are combustible substances, are generally used as electrolytes, but recently, all-solid-state batteries have attracted attention in order to develop safer batteries. An all-solid-state battery replaces a combustible organic electrolyte with a non-combustible inorganic solid electrolyte or the like, and has improved safety compared to conventional batteries. In addition, in such an all-solid-state battery, it is expected that the performance of the battery will be further improved. For example, it is expected that the energy density of the battery will be increased.

In the all-solid-state battery as described above, for example, it is known that a solid electrolyte layer is formed by press-molding a material having high ion conductivity (see, for example, Patent Document 1, etc.). It has also been proposed to mold solid electrolyte glass particles containing an element such as Li into a sheet and apply this to a solid electrolyte (see, for example, Patent Document 2).

JP 2014-41723 A JP 2010-250982 A

However, as in the above-mentioned technology, the solid electrolyte formed only of powder materials is designed to conduct by contacting powders, so the contact area is small, compared to lithium batteries using electrolyte solution. However, there is a problem that the output characteristics tend to be inferior. In addition, when a powder material is used, it is difficult to form a thin film sheet consisting of a layer formed of a single material, and there is a problem that the manufacturing process tends to be complicated.

The present invention has been made in view of the above, and can provide an all-solid-state battery with excellent energy density and output characteristics, and enables the mass production of all-solid-state batteries by a continuous process. An object of the present invention is to provide a solid electrolyte sheet and a manufacturing method thereof. Another object of the present invention is to provide an all-solid-state battery including the solid electrolyte sheet and a method for manufacturing the same.

As a result of intensive studies to achieve the above object, the inventors of the present invention found that the above object can be achieved by filling the through-holes formed in the support with a solid electrolyte in the solid electrolyte sheet. was completed.

That is, the present invention relates to the following solid electrolyte sheet and method for producing the same, all-solid battery, and method for producing an all-solid battery.
Section 1. comprising a solid electrolyte and a support,
The support has a plurality of through holes,
A solid electrolyte sheet, wherein the through holes are filled with the solid electrolyte.
Section 2. Item 2. The solid electrolyte sheet according to Item 1, wherein the solid electrolyte contains at least lithium element.
Item 3. 3. The solid electrolyte sheet according to Item 1 or 2, wherein the solid electrolyte further contains at least one of elemental sulfur and elemental phosphorus.
Section 4. 4. The solid electrolyte sheet according to any one of items 1 to 3 above, wherein the solid electrolyte includes a glass solid electrolyte.
Item 5. 5. The solid electrolyte sheet according to any one of items 1 to 4, wherein the support is made of an organic material.
Item 6. 6. The solid electrolyte sheet according to any one of items 1 to 5, wherein the through-holes are formed so that the opening ratio of the support is 50 to 99%.
Item 7. A method for producing a solid electrolyte sheet according to any one of items 1 to 6 above,
a step of filling a plurality of through-holes formed on the support with a solid electrolyte;
pressing a support in which the through-holes are filled with the solid electrolyte;
A method for producing a solid electrolyte sheet.
Item 8. 8. The method for producing a solid electrolyte sheet according to Item 7, further comprising the step of forming the support by etching an organic material.
Item 9. An all-solid battery comprising the solid electrolyte sheet according to any one of items 1 to 6 above.
Item 10. A method for producing an all-solid-state battery, comprising a step of pressing a laminate formed including the solid electrolyte sheet according to any one of Items 1 to 6 above.
Item 11. 11. The method for producing an all-solid-state battery according to Item 10, wherein the laminate is pressurized at a pressure of 1000 MPa or less.
Item 12. The method for producing an all-solid-state battery according to Item 10 or 11, further comprising a step of treating at an ambient temperature of 800° C. or lower.

By incorporating the solid electrolyte sheet according to the present invention into an all-solid battery such as a lithium battery, the energy density and output characteristics of the battery can be improved. Moreover, by using the solid electrolyte sheet, it is possible to mass-produce all-solid-state batteries through a continuous process.

The method for producing a solid electrolyte sheet according to the present invention is suitable for producing the above solid electrolyte sheet. The solid electrolyte sheet obtained by the above production method can improve the energy density and output characteristics of the battery by incorporating it into an all-solid battery such as a lithium battery.

Since the all-solid-state battery according to the present invention includes the above-described solid electrolyte sheet, it is excellent in energy density and output characteristics.

The method for manufacturing an all-solid-state battery according to the present invention is a method suitable for manufacturing the above-described all-solid-state battery. In particular, by using the above-described solid electrolyte sheet, it is possible to mass-produce all-solid-state batteries by a continuous process. is.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows an example of embodiment of the solid electrolyte sheet of this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an example of an embodiment of a method for producing a solid electrolyte sheet of the present invention and is a schematic diagram of a production flow. It is a scanning ion microscope (SIM) image in which a part of the surface of the solid electrolyte sheet produced in Example is enlarged. 4 is a graph showing the results of charge/discharge characteristics.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail.

FIG. 1 shows an example of an embodiment of the present invention, and (A) is a schematic diagram showing an example of an embodiment of a solid electrolyte sheet.

The solid electrolyte sheet A of this embodiment includes a solid electrolyte 1 and a support 2. The support 2 has a plurality of through holes 3, 3, . is filled to

The type of solid electrolyte 1 is not particularly limited, and for example, a material that can be used as a solid electrolyte for an all-solid battery can be used. For example, the solid electrolyte may include a glass solid electrolyte. Examples of glass solid electrolytes include glass solid electrolytes that are solid at room temperature (for example, 25° C.) and have ion conductivity. A glass solid electrolyte is a solid electrolyte that does not contain a crystalline phase, ie, no peaks are observed by X-ray diffraction measurement.

Examples of glass solid electrolytes include substances containing at least lithium (Li) element. In particular, the glass solid electrolyte preferably contains at least one of sulfur (S) element and phosphorus (P) element as constituent elements in addition to lithium (Li) element.

Specific examples of glass solid electrolytes include Li ₂ S—SiS ₂ , Li ₂ S—GeS ₂ , Li ₂ SP ₂ S ₅ , Li ₂ S—B ₂ S ₃ , Li ₂ S—SiS ₂ —Li ₃ PO ₄ , Li ₂ S—SiS ₂ —Li ₂ SO ₄ , Li ₂ SP ₂ S ₅ —LiI, Li ₂ SP 2S ₅ —P ₂ O ₅ —LiI, Li ₂ S _— B ₂ S ₃ — LiI, Li ₂ SP ₂ S ₅ --Li ₂ O--LiI, Li ₂ S--SiS ₂ --B ₂ S ₃ --LiI and the like.

Note that the glass solid electrolyte may contain other elements.

The glass solid electrolytes exemplified above are manufactured by known manufacturing methods. For example, it can be produced using lithium sulfide (Li ₂ S), diphosphorus pentasulfide (P ₂ S ₅ ), elemental phosphorus, elemental sulfur, etc. as raw materials. Specifically, the glass solid electrolyte is produced by a method of melt-reacting one or a mixture of two or more of the above raw materials and then quenching, or a method of processing by a so-called mechanical milling method. By heat-treating the glass solid electrolyte thus obtained, a crystalline solid electrolyte, a so-called glass-ceramic solid electrolyte, can be obtained.

When the glass solid electrolyte is produced by using lithium sulfide and diphosphorus pentasulfide, the molar ratio of the two (lithium sulfide: diphosphorus pentasulfide) can be 60:40 to 85:15, which is preferable. is 70:30 to 80:20.

The solid electrolyte 1 may be other than a glass solid electrolyte, and other examples include semi-solid polymer electrolytes such as polyethylene oxide, polypropylene oxide, polyvinylidene fluoride, or polyacrylonitrile containing lithium salts. The solid electrolyte 1 is a so-called gel-type solid electrolyte in which an electrolytic solution is retained in a polymer solid electrolyte such as a polymer containing at least one selected from a polyethylene oxide polymer, a polyorganosiloxane chain and a polyoxyalkylene chain. It may be an electrolyte. _In addition, the solid electrolyte ₁ can also include a _sulfide crystalline solid _electrolyte , such as _{Li3.25Ge0.25P0.75S4} , _{Li10GeP2S12 , Li6PS5Cl} , _etc. However, the sulfide crystalline solid electrolyte is not limited to these elemental compositions.

The form of the solid electrolyte 1 is not particularly limited, and can be powdered, for example. Also, the shape of the solid electrolyte 1 is not particularly limited, and examples thereof include a spherical shape, an oval spherical shape, a needle shape, a flake shape, and the like.

The particle size of the solid electrolyte 1 is not particularly limited, and can be, for example, 0.01 μm or more and 50 μm or less. Since a sufficient contact area with the substance can be secured, a decrease in ionic conductivity can be suppressed. In particular, by being finely divided into the above range, it is possible to suppress reaggregation, reduction in bulk density, and increase in interfacial resistance due to excessive fineness, and when forming a film, a uniform and thin solid electrolyte with less unevenness. Easy to get layers. Moreover, when the battery is formed, a large contact area with the active material in the electrode layer can be ensured, an increase in the internal resistance of the battery can be easily suppressed, and the charge/discharge rate can be improved. A more preferable particle size of the solid electrolyte 1 is 0.1 μm or more and 10 μm or less. The particle size can be obtained by a laser diffraction particle size distribution measuring method or the like.

The support 2 is, for example, a member formed in the shape of a sheet, film, or thin film.

The material constituting such a support 2 is not particularly limited, but from the viewpoint of imparting excellent mechanical properties, electrical properties and durability to the all-solid-state battery, mechanical strength, heat resistance and chemical stability are required. It is preferable to have

Materials constituting the support 2 include polyimide, polyether ether ketone (PEEK), polyamideimide, polyetherimide (PEI), polytetrafluoroethylene (PTFE), and tetrafluoroethylene-perfluoroalkyl vinyl ether polymer. (PFA), nylon (polyamide), polyethylene (PE), polyacetal, polyester, polyethylene terephthalate (PET), polycarbonate (PC), polypropylene (PP), acrylic, triacetate (TAC), polyphenylene sulfide (PPS), polyethylene naphthalate (PEN), polystyrene, cellophane, and the like. Polyimide is preferably used as the material for the support 2 because it has excellent mechanical, electrical and chemical properties over a wide temperature range. The support 2 may be composed of one kind of material, or may be composed of two or more kinds of materials.

Also, the material constituting the support 2 may be an organic material having ion conductivity, glass, ceramics, or the like.

The support 2 is preferably made of an etchable material. In this case, since the through-holes 3 can be formed by etching, as will be described later, the support 2 can be easily obtained, and there is also the advantage that the number and shape of the through-holes 3 to be formed can be easily controlled. be.

The thickness of the support 2 is not limited, and can be, for example, 1 to 500 μm. More preferably, the thickness of the support 2 is 5 to 50 μm. Within this range, reduction in weight and thickness of the all-solid-state battery is less likely to be hindered, and deterioration in output characteristics is less likely to occur.

The shape of the support 2 in a plan view is not particularly limited, and can usually be a rectangular shape, but is not limited to this. The size of the support 2 is also not particularly limited, and can be appropriately set according to the size of the all-solid-state battery.

A plurality of through holes 3 , 3 , . . . are formed in the support 2 . These through holes 3 are holes formed through the support 2 in the thickness direction.

The size of the opening surface of the through-hole 3 is not particularly limited as long as it is large enough to be filled with the solid electrolyte 1 . For example, if the opening surface area of the through hole 3 is in the range of 0.01 μm ² to 1 mm ² , the solid electrolyte 1 can be easily filled. More specifically, if the opening surface of the through-hole 3 is square, the length of one side can be in the range of 10 to 1000 μm. In that case, the diameter (major axis) can be in the range of 10 to 1000 μm. Within this range, the through holes 3 can be filled with a sufficient amount of the solid electrolyte 1 .

The aperture ratio of the support 2 can be 50 to 99%. Within this range, it becomes easier to prevent the solid electrolyte 1 filled in the through-holes 3 from coming off, and a decrease in the ionic conductivity of the solid electrolyte sheet A can be suppressed. A more preferable aperture ratio of the support 2 can be 80 to 99%.

The aperture ratio of the support 2 referred to here can be calculated by the following equation.
Aperture ratio (%) of support 2 = (A/B) x 100
Here, A is the total opening area of the through holes 3, and B is the projected area of the support 2 (that is, the apparent area of the support 2).

Therefore, the aperture ratio of the support 2 can be said to be the ratio of the through holes 3 occupying the surface of the support 2 .

The number of through-holes 3 formed in the support 2 is also appropriately set according to the target value of the aperture ratio, and the number is not limited.

The through-holes 3 may be formed uniformly over the entire surface of the support 2, for example, may be arranged regularly, or may be arranged irregularly. Also, all of the plurality of through holes 3 may be formed with the same shape and size, or some or all of the through holes 3 may be formed with different shapes or sizes.

In the solid electrolyte sheet A of the present embodiment, the solid electrolyte 1 described above exists in a state in which the through holes 3 are filled. That is, the solid electrolyte 1 exists in a state of being embedded in the through holes 3 .

It is preferable that the solid electrolyte 1 is filled in all the through-holes 3, so that high output characteristics can be imparted to the all-solid-state battery. Moreover, in this case, it is easy to prevent a decrease in ionic conductivity.

The solid electrolyte 1 is preferably densely filled in the through-holes 3. In this case, it becomes easier to prevent the solid electrolyte 1 from dropping out of the through-holes 3, thereby preventing deterioration of the output characteristics of the all-solid-state battery. easier. However, as long as the solid electrolyte 1 does not drop out of the through hole 3, the through hole 3 is not necessarily densely filled with the solid electrolyte 1.

For example, in the solid electrolyte sheet A, the volume ratio of the support 2 to the solid electrolyte 1 can be in the range of 1:0.5 to 1:500. Within this range, it becomes easier to prevent the solid electrolyte 1 from dropping out of the through-hole 3, and it becomes easier to prevent the deterioration of the output characteristics of the all-solid-state battery. Preferably, the volume ratio of the support 2 to the solid electrolyte 1 is in the range of 1:1 to 1:300.

The solid electrolyte 1 is preferably filled in a state in which the powders thereof are fused together. The presence of the solid electrolyte 1 in such a fused state facilitates the formation of a solid electrolyte sheet A having excellent ionic conductivity, and also facilitates the prevention of the solid electrolyte 1 from falling out of the through-holes 3.

The solid electrolyte sheet A formed as described above may further contain a binder. However, since the solid electrolyte 1 is held by the support 2 by being filled in the through-holes 3, the solid electrolyte sheet A of the present embodiment does not necessarily require a binder. That is, the solid electrolyte sheet A of the present embodiment can be made binderless. If the solid electrolyte powder has excellent wettability, it is easier to achieve binderless.

When a binder is included, the binder is not particularly limited, and polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyimide (PI), polyamideimide (PAI), polyethylene, polypropylene, ethylene propylene Polymer materials such as diene rubber (EPDM), natural butyl rubber (NBR), polyvinyl alcohol, cellulosic materials, polyvinylpyrrolidone, and styrene-butadiene rubber (SBR) are exemplified. These exemplified polymeric materials can be used alone or in combination of two or more.

The amount of the binder compounded can be, for example, 0.1 to 10 parts by mass per 100 parts by mass of the solid electrolyte. Within this range, the through holes 3 can be easily filled with the solid electrolyte 1 densely, and the solid electrolyte 1 can be easily dropped. is easily prevented, and the flexibility of the solid electrolyte sheet A is easily maintained.

The solid electrolyte sheet A is formed by filling the through holes 3 of the support 2 with the solid electrolyte 1 . Therefore, by incorporating such a solid electrolyte sheet A into an all-solid-state battery, the all-solid-state battery can be made thinner than the conventional one, and the size of the all-solid-state battery can be increased and laminated easily.

In particular, since the through-holes 3 of the support 2 are filled with the solid electrolyte 1, the solid electrolyte 1 is less likely to come off. For example, when inorganic fibers such as non-woven glass paper are used as a support, the inorganic fibers tend to form a non-uniform and highly variable network structure, resulting in a low aperture ratio and a long ion conduction path. There is a possibility that the ionic conductivity and the output characteristics of the battery may deteriorate. On the other hand, in the support 2 of the present embodiment, the aperture ratio of the through-holes 3 is high, and the solid electrolyte 1 can be easily filled into the through-holes 3 densely, thereby easily preventing the solid electrolyte 1 from coming off. properties and output characteristics.

Furthermore, since the through-holes 3 are formed in the support 2 with excellent dimensional accuracy and a large opening ratio, the existence distribution of the solid electrolyte 1 and the support 2 is highly controlled. In addition, in the solid electrolyte sheet of the present embodiment, since the solid electrolyte 1 itself has a continuous self-supporting structure, the introduction of the support 2 is less likely to reduce the ionic conductivity, and the ionic conduction path is less than the thickness of the sheet. It can be made as short as possible, and as a result, excellent output characteristics are exhibited.

Further, the solid electrolyte sheet A has performance as an electronic insulating sheet in an all-solid battery, and thus also serves as a separator. As a result, a short-circuit current is less likely to occur, and the internal resistance can be lowered. Moreover, such an all-solid-state battery is also excellent in safety.

By incorporating the solid electrolyte sheet A into an all-solid-state battery such as a lithium battery, the energy density and output characteristics of the battery can be improved. In addition, since the solid electrolyte sheet A is configured as described above, it can be easily laminated with a large area and a bipolar structure, and can be applied to various all-solid-state batteries. Moreover, by using the solid electrolyte sheet, it is possible to mass-produce all-solid-state batteries through a continuous process.

The solid electrolyte sheet A is applied to the solid electrolyte layer of an all-solid battery (for example, an all-solid secondary battery). An all-solid battery is formed by including a positive electrode, a negative electrode, and a solid electrolyte sheet A, for example. In this case, the solid electrolyte sheet A is arranged so as to be interposed between the positive electrode and the negative electrode. The all-solid-state battery can have a known structure as long as it has the solid electrolyte sheet A.

The types of positive and negative electrodes used in the all-solid-state battery are not particularly limited. For example, an all-solid-state battery may be composed of a known positive electrode and negative electrode, but is not limited to these.

The positive electrode has a positive electrode active material-containing layer and a positive electrode current collector, and for example, a known positive electrode can be used, but it is not limited to these. For example, if the all-solid-state battery is a lithium-ion secondary battery, the positive electrode is preferably made of a material capable of intercalating and deintercalating lithium. Examples of positive electrode current collectors include aluminum and the like. The positive electrode active material and conductive agent are also not particularly limited.

The negative electrode is formed by having a negative electrode current collector and a negative electrode active material-containing layer, and for example, a known negative electrode can be used, but the present invention is not limited to these. For example, if the all-solid-state battery is a lithium-ion secondary battery, metal lithium, metal indium, or a material capable of intercalating and deintercalating lithium can be used as the negative electrode active material.

The all-solid-state battery as described above is provided with the solid electrolyte sheet A and is excellent in energy density and output characteristics. In addition, since the all-solid-state battery described above is formed with the solid electrolyte sheet A, it can be made thinner and lighter than before. In addition, in the all-solid-state battery described above, although the support 2 is interposed, the through holes 3 of the support 2 are filled with the solid electrolyte 1, so that the ionic conductivity is less likely to decrease. is.

The type of all-solid-state battery is not particularly limited, and it can be formed into, for example, a lithium-ion secondary battery, a sodium-ion secondary battery, or the like, by selecting materials that constitute the all-solid-state battery.

The all-solid-state battery can be used, for example, as a storage battery for mobile communication devices, portable electronic devices, electric bicycles, electric two-wheeled vehicles, electric vehicles, small household power storage devices, and the like.

Next, a method for manufacturing a solid electrolyte sheet and an all-solid battery will be described. Although the method for manufacturing the solid electrolyte sheet is not particularly limited, one example thereof is shown here.

FIG. 2 schematically shows the manufacturing flow of the solid electrolyte sheet A. As shown in FIG.

The method for producing a solid electrolyte sheet according to the present embodiment comprises a step of filling a plurality of through holes 3 formed on a support 2 with a solid electrolyte 1 (hereinafter abbreviated as a "filling step"), and filling the through holes 3 with and a step of pressing the support 2 filled with the solid electrolyte 1 (hereinafter abbreviated as “pressing step”).

In the filling step, the solid electrolyte 1 is applied onto the support 2 , and the through holes 3 formed in the support 2 are filled with the solid electrolyte 1 . The support 2 used here is the same as the support 2 described above, and the solid electrolyte 1 used here is the same as the solid electrolyte 1 described above. Moreover, the form of the through-holes 3 formed in the support 2 is also as described above.

The solid electrolyte 1 is applied to the support 2 by, for example, coating a dry powder of the solid electrolyte 1 on the support 2, preparing a dispersion of the solid electrolyte 1 in advance, and applying this onto the support 2. It can be done by a method that causes The method of application is not particularly limited, and examples thereof include application by a doctor blade, bar coater, applicator, spray coating, electrostatic coating, brush coating, electrostatic printing, electrostatic spray deposition, and aerosol deposition. etc., known means can be employed.

When the solid electrolyte 1 is applied to the support 2 , at least the through holes 3 formed in the support 2 are filled (embedded) with the solid electrolyte 1 . In this case, the solid electrolyte 1 may cover portions of the support 2 other than the through holes 3 . In this case, for example, if the solid electrolyte 1 having a particle size smaller than the size of the opening surface is used, the filling efficiency is improved, and the thinner the support 2 is, the better the filling efficiency is.

Alternatively, the through holes 3 can be filled with the solid electrolyte 1 by preparing a dispersion of the solid electrolyte 1 in advance and immersing the support 2 in this dispersion.

In the filling step, when the dispersion of the solid electrolyte 1 is used to apply the solid electrolyte 1 to the support 2, the solid content concentration of the solid electrolyte 1 contained in the dispersion is, for example, 20 to 80% by mass. be able to. Examples of the dispersion medium in this case include dehydrated toluene and dehydrated heptane. The method of preparing the dispersion is not particularly limited, either, and it may be prepared by blending predetermined amounts of a dispersion medium, a solid electrolyte, a binder added as necessary, and the like.

After the above application, a treatment for drying the dispersion medium may be performed as necessary. A drying means is not limited, and a known method can be adopted.

In the filling step, it is preferable that all of the plurality of through-holes 3 are filled with the solid electrolyte 1. In this case, the obtained solid electrolyte sheet A can impart excellent output characteristics to the all-solid-state battery. .

A method for forming the support will now be described.

A method for forming the through holes 3 in the support 2 is not particularly limited. First, a sheet member, a film member, or the like for forming the support 2 is prepared, and the through holes 3 can be formed by etching this member. Such a member is preferably made of an insulating organic material. In this case, the through-holes 3 can be easily formed by etching, and the size of the through-holes 3, the locations where they are formed, the aperture ratio, and the like can be easily controlled. Examples of insulating organic materials include polyimide (PI), polycarbonate (PC), polyphenylene sulfide (PPS), nylon (polyamide), polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (TFE -PFA) and the like are exemplified.

A particularly preferred method for forming the through holes 3 is to selectively perform etching using lithography. Thus, when the support 2 is formed by selective etching based on lithography, it can be designed to have various penetrating structures and aperture ratios, and can be obtained as a continuously penetrating perforated sheet with high dimensional accuracy. It is possible to manufacture a sheet having a thickness of 5 μm or more. Conditions for the etching treatment are not particularly limited, and known methods such as wet etching and dry etching may be employed. The size and aperture ratio of the through-holes can be controlled, for example, by the pattern structure drawn on the photomask.

The support 2 having the through holes 3 as described above may be included in the method for manufacturing the solid electrolyte sheet A of the present embodiment. That is, the method for manufacturing the solid electrolyte sheet A of the present embodiment may further include a step of forming the support 2 by etching the organic material. As a result, the support 2 having the through holes 3 formed by etching can be obtained. The step of forming such a support 2 may be included in the filling step described above, or may precede the filling step.

In the pressing step, the support 2 in which the solid electrolyte 1 is filled in the through holes 3 obtained in the filling step is pressed. A known device such as a heating press, a heating roll press, or the like can be used for pressing.

The pressure in the pressing step can be, for example, 0.1 to 500 MPa. Within this range, the filled solid electrolyte 1 is less likely to fall off, damage to the support 2 can be suppressed, and the solid electrolyte It is easy to improve the strength and electrical conductivity (conductivity) of the electrolyte sheet A. A more preferred pressure is 10 to 400 MPa, and a particularly preferred pressure is 30 to 360 MPa.

The heating temperature in the pressing step can be, for example, 10 to 400° C. Within this range, the filled solid electrolyte 1 is less likely to fall off, and damage to the support 2 can be suppressed. It is easy to improve the strength and electrical conductivity (conductivity) of the solid electrolyte sheet A. A more preferred temperature is 25 to 360°C, and a particularly preferred temperature is 25 to 300°C.

In the pressing step, the pressure and heat may be applied simultaneously, or the pressure and heat may be applied independently. For example, pressurization may be followed by heating, or vice versa.

The pressing time in the pressing step is not particularly limited, but can be, for example, 0.0001 minute to 5 hours. Within this range, the manufacturing process does not become too long, and falling off of the filled solid electrolyte 1 can be easily suppressed.

Further, when the above-described pressing step is performed by a heated roll press, the rotation speed of the rolls can be 0.1 to 10.0 m/min, and the pressure load applied by the rolls can be 1 to 80 kN.

Through the pressing process, the solid electrolyte sheet A described above is manufactured.

According to the manufacturing method described above, the solid electrolyte sheet A can be stably manufactured because it is constituted by a simple process.

In particular, the production method uses the support 2, so that the process window for battery production is wide. For example, since the strength of the support 2 is high and the operating temperature range can be widened, there is an advantage that the pressure and temperature range in the manufacturing process can be set wider. In addition, since it is possible to increase the area and reduce the thickness, it is advantageous as a process, and since a continuous process is possible, it is easy to divert to a battery manufacturing process.

Furthermore, since the support 2 is formed by selective etching of an organic material, for example, it has a highly controlled through-pore structure, so that a thin and strong solid electrolyte sheet A can be manufactured. In particular, since the obtained solid electrolyte sheet is smooth and has high strength, it is easy to manufacture a sheet-like battery using a positive electrode and a negative electrode, and a continuous process such as a so-called roll-to-roll method can be realized.

Next, a method for manufacturing an all-solid battery using the solid electrolyte sheet A or the solid electrolyte sheet A manufactured by the manufacturing method described above will be described.

The method for manufacturing an all-solid-state battery according to the present embodiment includes a step of pressing a laminate formed including the solid electrolyte sheet A described above.

The laminate is formed by laminating, for example, a positive electrode active material layer, a solid electrolyte sheet A, and a negative electrode active material layer in this order. Current collectors may be formed on the surfaces of the positive electrode active material layer and the negative electrode active material layer opposite to the solid electrolyte sheet A, respectively. The positive electrode active material layer, the negative electrode active material layer, and the current collector that constitute such a laminate can be made of known materials, for example.

The laminate is formed by laminating at least a positive electrode active material layer, a solid electrolyte sheet A, and a negative electrode active material layer in this order. By pressurizing such a laminate, an all-solid battery can be formed. Alternatively, the positive electrode active material layer, the solid electrolyte sheet A, and the negative electrode active material layer, which are formed in a sheet shape, are fed independently by rolls or the like, and these layers are joined to form a laminate, and the laminate is formed. A so-called roll-to-roll method, which is a method of manufacturing a laminate by pressing with rolls, may be employed. In such a roll-to-roll method, since the laminate can be continuously formed, there is an advantage that all-solid-state batteries can also be continuously produced.

The pressure when pressing the laminate can be, for example, 1000 MPa or less. Within this range, the performance of the solid electrolyte sheet A is unlikely to deteriorate, and an all-solid battery with good characteristics can be obtained. The pressure is preferably 0.1-1000 MPa, more preferably 10-500 MPa.

The method for manufacturing an all-solid-state battery of the present embodiment can further include a step of processing at an ambient temperature of 800° C. or less. In this case, the adhesion between the layers is improved and a dense interface is obtained, thereby increasing the contact area and improving the internal resistance and output characteristics. Such a step may be performed before or after the step of pressing the laminate, or may be performed simultaneously with the step of pressing the laminate. A preferable ambient temperature is 25 to 500°C, more preferably 25 to 360°C.

According to the method for manufacturing an all-solid-state battery described above, an all-solid-state battery can be easily manufactured. In particular, since the solid electrolyte sheet A is used as a layer for forming the solid electrolyte, a large amount of all-solid-state batteries can be manufactured by a continuous process, and the method is excellent in manufacturing efficiency.

All-solid-state batteries such as lithium-ion secondary batteries and sodium-ion secondary batteries can be produced by the above production method, for example, by selecting materials to be used.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the embodiments of these examples.

(Example 1)
Li ₂ S and P ₂ S ₅ were prepared as starting materials, and 1.5 g of a mixture prepared with a molar ratio of 75:25 and 90 g of zirconia balls having a diameter of 4 mm were placed in a 45 mL zirconia pot, A sulfide glass powder having an average particle size of about 10 μm was obtained by performing mechanical milling for 24 hours in an argon atmosphere using a planetary ball mill apparatus at a rotation speed of 510 rpm. Vitrification of the obtained powder was confirmed by powder X-ray diffraction measurement, and it was confirmed that a glass solid electrolyte (sulfide solid electrolyte) was produced.

Next, the glass solid electrolyte, dehydrated heptane, and dehydrated butyl ether were placed in a planetary ball mill pot, zirconia balls with a diameter of 2 mmΦ were added, and the mixture was stirred at 250 rpm for 20 hours to obtain an electrolyte slurry. The slurry was dried to obtain a solid electrolyte powder having an average particle size of about 1-5 μm. The ionic conductivity of the obtained solid electrolyte powder at room temperature (25° C.) was 2.0×10 ⁻⁴ S·cm ⁻¹ .

On the other hand, a polyimide sheet (polyimide film Kapton (registered trademark), manufactured by Toray DuPont Co., Ltd.) is fixed on a glass substrate, chromium is vapor-deposited on the surface, and then a photoresist (OFPR-800LB, manufactured by Tokyo Ohka Kogyo Co., Ltd.). was applied. After that, photolithography was performed using a mask having a pattern with an aperture ratio of 88% and having holes of 800 μm square on each side. The chromium was removed by wet etching, and the polyimide portion was removed by dry etching. Thereafter, unnecessary chromium was removed again by wet etching to obtain a polyimide support having through-holes of 800 μm square. The aperture ratio of the support was 88%.

After bonding the aluminum foil electrostatically printed with the solid electrolyte powder obtained as described above on both sides of the support, using a heating roll press (SA-602-S manufactured by Takumi Giken Co., Ltd.), 100 ° C. Heating and pressure treatment were performed under conditions of 20 kN and a roll rotation speed of 0.4 m/min. After that, the aluminum foil was peeled off to obtain a solid electrolyte sheet with a thickness of 50 μm. Next, the solid electrolyte sheet was punched out to have a diameter of 10 mm, and was arranged into a circular sheet shape. The ionic conductivity of the obtained solid electrolyte sheet at room temperature (25° C.) was measured by the AC impedance method (AC amplitude 10 mV, frequency 10 MHz to 100 Hz) and was 1.6×10 ⁻⁴ S·cm ⁻¹ . rice field. In addition, this sheet is a self-supporting sheet with good handleability and strength that allows it to be moved without chipping of the periphery or falling off of powder from the through-holes even if it is sandwiched with tweezers or punched with a punch. there were.

(Example 2)
A polyimide support was obtained in the same manner as in Example 1, except that the through-holes were formed to be 200 μm square. The aperture ratio of the support was 80%.

On the other hand, prepare an aluminum foil electrostatically printed with a solid electrolyte powder obtained in the same manner as in Example 1, place the polyimide support on the printed surface, electrostatically print the solid electrolyte thereon, and then , After placing the aluminum foil, a heating roll press was used to heat and pressurize under the conditions of 100° C., 20 kN, and a roll rotation speed of 0.4 m/min. After that, the aluminum foil was peeled off to obtain a solid electrolyte sheet with a thickness of 37 μm. Next, the solid electrolyte sheet was punched out to have a diameter of 10 mm, and was arranged into a circular sheet shape.

(Example 3)
A solid electrolyte powder obtained in the same manner as in Example 1 was dispersed in dehydrated heptane to prepare a solid electrolyte slurry having a solid concentration of 30 wt %. Next, the prepared slurry was applied using a bar coater onto the polyimide support (opening ratio 80%) having 200 μm square through-holes prepared in Example 2, and dried by heating at about 120°C. After that, a heating roll press was used to heat and pressurize under conditions of 100° C., 30 kN, and a roll rotation speed of 0.4 m/min to obtain a solid electrolyte sheet with a thickness of 93 μm.

(Example 4)
A polyimide support was obtained in the same manner as in Example 1, except that the opening ratio was 80%.

A solid electrolyte powder obtained in the same manner as in Example 1 was placed on both sides of the polyimide support and pressed with a mold press at 360 MPa for 5 minutes to obtain a solid electrolyte sheet with a thickness of 138 μm.

(Comparative example 1)
A solid electrolyte powder prepared in the same manner as in Example 1 was pressed with a press to form pellets. When the pellet was checked, cracks were found, and when the pellet was lifted with tweezers, it was broken. When the thickness of the damaged one was measured, it was 122 μm. Even when the thickness of the pellet was 295 μm, breakage still occurred.

(Observation of solid electrolyte sheet)
FIG. 3 is an enlarged SIM image of a part of the surface of the solid electrolyte sheet produced in Example. From this figure, it was found that the through-holes of the support were filled with the solid electrolyte powder.

(Production of battery)
Using the solid electrolyte sheet of each example obtained as described above, a battery was produced by the following procedure.

Lithium nickel manganese cobaltate (LiNi _1/3 Mn _1/3 Co _1/3 O ₂ (NMC)) coated with lithium niobate (LiNbO ₃ ) was used as the positive electrode material, and a 0.1 mm thick Indium (In) or graphite was prepared.

Formation of positive electrode The above LiNbO3 _- coated NMC, the solid electrolyte glass powder prepared in Example 1, the conductive material (acetylene black) and the binder (SBR) were mixed in a solvent ( A positive electrode mixture slurry dispersed in dehydrated heptane) was applied to a positive electrode current collector foil (aluminum foil, thickness 18 μm) using a doctor blade, and air dried at room temperature to form a positive electrode.

Formation of Negative Electrode 1 Indium was used as the negative electrode.

The forming active material (graphite) of the negative electrode 2, the solid electrolyte glass powder prepared above, the conductive material (acetylene black) and the binder (SBR) were added to the solvent (dehydrated heptane ) was applied to a negative electrode collector foil (electrolytic copper foil, thickness 10 μm) using a doctor blade, and dried naturally at room temperature to form a negative electrode.

Production of Battery 1 The above positive electrode and the solid electrolyte sheet of Example 4 were superimposed and pressed at 360 MPa by a pressing device. Thus, battery 1 (In negative electrode/solid electrolyte sheet/NMC positive electrode) was obtained.

Manufacture of Battery 2 Using the negative electrode 2 and the positive electrode described above, the solid electrolyte sheet of Example 1 was sandwiched between them, laminated, and pressed at 180 MPa with a press to obtain battery 2 . The obtained battery 2 is formed by laminating a current collector, a negative electrode mixture, a solid electrolyte sheet, a positive electrode mixture, and a current collector in this order. The thickness of the battery 2 was 160 μm.

(Charge/discharge evaluation)
The batteries (batteries 1 and 2) produced as described above were attached to a charge/discharge measuring device, and charge/discharge evaluation was performed.

Charge/discharge conditions of battery 1 Measurement temperature: 25°C
Current density: 20 μA/cm ²
Voltage range: 3.7-2.5V
As a result, the initial charge capacity was 145 mAh/g (converted to the weight of the positive electrode active material), the 2nd discharge capacity was 88 mAh/g (converted to the weight of the positive electrode active material), and the 2nd charge/discharge efficiency was 88%.

Charge/discharge conditions of battery 2 Measurement temperature: 25°C
Current density: 60 μA/cm ²
Voltage range: 4.2-3.0V
As a result, the initial charge capacity was 68 mAh/g (converted to the weight of the positive electrode active material), the 2nd discharge capacity was 49 mAh/g (converted to the weight of the positive electrode active material), and the 2nd charge/discharge efficiency was 88%.

FIG. 4(a) shows the results of the charge/discharge evaluation of Battery 1, and FIG. 4(b) shows the results of the above charge/discharge evaluation of Battery 2, respectively.

A solid electrolyte sheet 1 solid electrolyte 2 support 3 through hole

Claims (8)

comprising a solid electrolyte and a support,
The support has a plurality of through holes,
The solid electrolyte is filled in the through holes,
The support is formed of an organic material other than a photosensitive resin,
The organic material other than the photosensitive resin is polyimide,
The thickness of the support is 5 to 50 μm.the law of nature,
The solid electrolyte contains at least lithium element , solid electrolyte sheet. comprising a solid electrolyte and a support,
The support has a plurality of through holes,
The solid electrolyte is filled in the through holes,
The support is formed of an organic material other than a photosensitive resin,
The organic material other than the photosensitive resin is polyimide,
The thickness of the support is 5 to 50 μm,
wherein the solid electrolyte comprises a glass solid electrolyte; Solid electrolyte sheet. comprising a solid electrolyte and a support,
The support has a plurality of through holes,
The solid electrolyte is filled in the through holes,
The support is formed of an organic material other than a photosensitive resin,
The organic material other than the photosensitive resin is polyimide,
The thickness of the support is 5 to 50 μm,
The through-holes are formed such that the opening ratio of the support is 50 to 99%. Solid electrolyte sheet. 3. The solid electrolyte sheet according to claim 1, wherein said solid electrolyte further contains at least one of elemental sulfur and elemental phosphorus. A method for producing a solid electrolyte sheet according to any one of claims 1 to 4 ,
a step of filling a plurality of through-holes formed by etching on the support with a solid electrolyte;
pressing a support in which the through-holes are filled with the solid electrolyte;
A method for producing a solid electrolyte sheet. An all-solid battery comprising the solid electrolyte sheet according to any one of claims 1 to 4 . A method for manufacturing an all-solid-state battery, comprising a step of pressing a laminate formed by including the solid electrolyte sheet according to any one of claims 1 to 4 . 8. The method for producing an all-solid-state battery according to claim 7 , wherein the laminate is pressurized at a pressure of 1000 MPa or less.

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