JP2022183500A - Solid-state battery and manufacturing method thereof - Google Patents

Abstract

To provide a solid-state battery which is capable of reducing an environmental load during manufacture and can be made lightweight.SOLUTION: In a solid-state battery 10, a part of a positive electrode collector 12, a positive electrode mixture layer 13, a solid electrolyte layer 14, a negative electrode mixture layer 15 and a part of a negative electrode collector 16 are successively laminated between a first encapsulation sheet 11A and a second encapsulation sheet 11B. In the solid-state battery 10, an insulation spacer 17 is present around the solid electrolyte layer 14, a first hot-melt adhesive 18A is interposed between the first encapsulation sheet 11A and the insulation spacer 17, and a second hot-melt adhesive 18B is interposed between the second encapsulation sheet 11B and the insulation spacer 17. In the solid-state battery 10, a third hot-melt adhesive is interposed between the first encapsulation sheet 11A and a positive electrode tab, and a fourth hot-melt adhesive is interposed between the second encapsulation sheet 11B and a negative electrode tab.SELECTED DRAWING: Figure 1

Description

The present invention relates to a solid-state battery and a method for manufacturing a solid-state battery.

Conventionally, lithium-ion secondary batteries have been widely used as solid-state batteries with high energy density. As an example of a lithium ion secondary battery, a solid lithium ion battery is known in which a positive electrode current collector, a positive electrode mixture layer, a solid electrolyte layer, a negative electrode mixture layer, and a negative electrode current collector are sequentially laminated. It is

As a method for producing a solid lithium ion battery, a positive electrode current collector, a positive electrode mixture layer, a solid electrolyte layer, a negative electrode mixture layer, and a negative electrode current collector are sequentially laminated and pressed to form a cell. A method is known in which, after obtaining, the cell is sandwiched between stainless steel support plates and sealed with a laminate film (see, for example, Patent Document 1). Also, a stainless steel support plate, a positive electrode current collector, a positive electrode mixture layer, a solid electrolyte layer, a negative electrode mixture layer, a negative electrode current collector, and a stainless steel support plate are sequentially laminated. A method of sealing with a laminate film after obtaining a cell by pressing with is also known.

JP 2017-10786 A

However, when the cell is not sealed, the positive electrode mixture layer, the solid electrolyte layer, and the negative electrode mixture layer are not sealed. will be required, and the environmental load will increase. Moreover, since a support plate made of stainless steel is used when sealing with a laminate film, the weight of the solid state lithium ion battery is increased.

SUMMARY OF THE INVENTION An object of the present invention is to provide a solid-state battery that can reduce the environmental load during manufacturing and can be made lighter.

In one aspect of the present invention, in a solid battery, a part of a positive electrode current collector, a positive electrode mixture layer, a solid electrolyte layer, and a negative electrode are placed between a first sealing sheet and a second sealing sheet. A mixture layer and a part of the negative electrode current collector are sequentially laminated, an insulating spacer is present around the solid electrolyte layer, and the first sealing sheet and the insulating spacer are separated from each other. A first hot-melt adhesive is interposed between the second sealing sheet and the insulating spacer, a second hot-melt adhesive is interposed between the second sealing sheet and the insulating spacer, and the positive electrode current collector A third hot melt adhesive is interposed between the region where the positive electrode mixture layer is not formed and the first sealing sheet, and the negative electrode mixture layer of the negative electrode current collector is A fourth hot melt adhesive is interposed between the unformed region and the second sealing sheet.

The insulating spacer may also exist around the positive electrode mixture layer.

Another aspect of the present invention is a method for manufacturing the solid-state battery, wherein a part of the positive electrode current collector is placed between the first sealing sheet and the second sealing sheet, The positive electrode mixture layer, the solid electrolyte layer, the negative electrode mixture layer, and part of the negative electrode current collector are sequentially arranged, and the first hot-melt adhesive and the insulating spacer are disposed. , and the second hot-melt adhesive are sequentially arranged, and the first sealing sheet is not formed with the positive electrode mixture layer of the positive electrode current collector. The third hot-melt adhesive is formed in a part of the region facing the region, and the second sealing sheet is formed in the region where the negative electrode mixture layer of the negative electrode current collector is not formed. The fourth hot-melt adhesive is formed on part of the region facing the .

Advantageous Effects of Invention According to the present invention, it is possible to provide a solid-state battery that can reduce the environmental load during manufacturing and can be made lighter.

It is a figure which shows an example of the solid-state battery of this embodiment. 2 is a diagram showing a method of manufacturing the solid-state battery of FIG. 1; FIG. FIG. 2 is a diagram showing a manufacturing method of the solid-state battery of Example 1; FIG. 2 is a diagram showing a manufacturing method of the solid-state battery of Example 1;

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of the solid battery of this embodiment.

Solid-state battery 10 includes part of positive electrode current collector 12, positive electrode mixture layer 13, solid electrolyte layer 14, and negative electrode mixture between first sealing sheet 11A and second sealing sheet 11B. The material layer 15 and part of the negative electrode current collector 16 are sequentially laminated. Here, in the solid battery 10, an insulating spacer 17 exists around the solid electrolyte layer 14, and a first hot melt adhesive 18A is provided between the first sealing sheet 11A and the insulating spacer 17. A second hot-melt adhesive 18B is interposed between the second sealing sheet 11B and the insulating spacer 17. As shown in FIG.

Here, the region of the positive electrode current collector 12 where the positive electrode mixture layer 13 is formed functions as a positive electrode, and the region of the positive electrode current collector 12 where the positive electrode mixture layer 13 is not formed functions as a positive electrode tab. do. A region of the negative electrode current collector 16 where the negative electrode mixture layer 15 is formed functions as a negative electrode, and a region of the negative electrode current collector 16 where the negative electrode mixture layer 15 is not formed functions as a negative electrode tab. .

A third hot-melt adhesive is interposed between the first sealing sheet 11A and the positive electrode tab, and a fourth hot-melt adhesive is interposed between the second sealing sheet 11B and the negative electrode tab. Adhesive intervenes.

The insulating spacer 17 may also exist around the positive electrode mixture layer 13 .

Moreover, the solid-state battery 10 may be sealed with a laminate film.

Examples of materials constituting the laminate film include aluminum and the like.

FIG. 2 shows an example of a method for manufacturing the solid-state battery 10. As shown in FIG.

The method for manufacturing the solid battery 10 includes placing a part of the positive electrode current collector 12, the positive electrode mixture layer 13, and the solid electrolyte layer 14 between the first sealing sheet 11A and the second sealing sheet 11B. , the negative electrode mixture layer 15 and part of the negative electrode current collector 16 are sequentially arranged, and the first hot melt adhesive 18A, the insulating spacer 17, and the second hot melt adhesive 18B are applied. It includes a step of heat-pressing in a state of sequential arrangement. Here, when heat-pressing in an atmospheric environment, it is necessary to seal in advance with a PPS film or the like.

Here, the first sealing sheet 11A has a third hot-melt adhesive 21A formed in part of the region facing the positive electrode tab, and the second sealing sheet 11B faces the negative electrode tab. A fourth hot-melt adhesive 21B is formed in part of the region where the

The cell obtained as described above includes the first sealing sheet 11A, the second sealing sheet 11B, the insulating spacer 17, the first hot-melt adhesive 18A, and the second hot-melt adhesive. The positive electrode mixture layer 13, the solid electrolyte layer 14, and the negative electrode mixture layer 15 are sealed by 18B. For this reason, in subsequent processes, an ultra-low dew point environment is no longer required, and the environmental load is reduced. Moreover, since the first sealing sheet 11A and the second sealing sheet 11B are used, the weight of the solid-state battery 10 is reduced.

The pressure during heat pressing is not particularly limited, but is, for example, 100 MPa or more and 2000 MPa or less.

The temperature during heat pressing is not particularly limited, but is, for example, 100° C. or higher and 2000° C. or lower.

The heat press time is not particularly limited, but is, for example, 5 seconds or more and 600 seconds or less.

When heat-pressing, press cushioning materials may be placed above the first sealing sheet 11A and below the second sealing sheet 11B. As a result, damage to the solid-state battery 10 is suppressed.

Examples of materials that constitute the first sealing sheet 11A and the second sealing sheet 11B include resins such as polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), and aluminum. be done.

Specific examples of the sealing sheet include, for example, an aluminum laminate film.

In addition, the first sealing sheet 11A and the second sealing sheet 11B may be the same or different.

Examples of the insulating material forming the insulating spacer 17 include resins such as polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), glass prepreg, and the like.

Examples of the shape of the insulating spacer 17 include a frame shape.

The first hot melt adhesive 18A and the second hot melt adhesive 18B contain thermoplastic resin.

The thermoplastic resin is not particularly limited as long as it can bond the first sealing sheet 11A (or the second sealing sheet 11B) and the insulating spacer 17, but examples include polypropylene and polyethylene. is mentioned.

Commercially available thermoplastic polypropylenes include, for example, PPa-F (manufactured by DNP).

The glass transition point of the thermoplastic resin is preferably -30°C or higher and 100°C or lower, more preferably -20°C or higher and 50°C or lower. When the glass transition point of the thermoplastic resin is −30° C. or higher, it becomes difficult to flow out during heat pressing, and when it is 100° C. or less, it becomes easy to adhere during heat pressing.

The first hot-melt adhesive 18A and the second hot-melt adhesive 18B may be the same or different.

Examples of the shape of the first hot-melt adhesive 18A and the second hot-melt adhesive 18B include a frame shape.

The third hot melt adhesive 21A and the fourth hot melt adhesive 21B contain thermoplastic resin.

The thermoplastic resin is not particularly limited as long as it can bond the first sealing sheet 11A (or the second sealing sheet 11B) and the positive electrode tab (or the negative electrode tab). , polyethylene and the like.

Commercially available thermoplastic polypropylenes include, for example, PPa-F (manufactured by DNP).

The glass transition point of the thermoplastic resin is preferably -30°C or higher and 100°C or lower, more preferably -20°C or higher and 50°C or lower. When the glass transition point of the thermoplastic resin is −30° C. or higher, it becomes difficult to flow out during heat pressing, and when it is 100° C. or less, it becomes easy to adhere during heat pressing.

The third hot-melt adhesive 21A and the fourth hot-melt adhesive 21B may be the same or different. Also, the third hot melt adhesive 21A and the fourth hot melt adhesive 21B may be the same as or different from the first hot melt adhesive 18A or the second hot melt adhesive 18B. good too.

Examples of the shape of the third hot-melt adhesive 21A and the fourth hot-melt adhesive 21B include a rod shape.

Note that the method for manufacturing the solid-state battery 10 may further include a step of sealing the cell with a laminate film.

Examples of materials constituting the laminate film include aluminum and the like.

Examples of the solid-state battery 10 include a semi-solid lithium ion battery, an all-solid lithium ion battery, an all-solid fluoride ion battery, and the like.

Well-known materials can be used as the materials constituting the positive electrode current collector 12, the positive electrode mixture layer 13, the solid electrolyte layer 14, the negative electrode mixture layer 15, and the negative electrode current collector 16, respectively.

A case where the solid-state battery 10 is an all-solid-state lithium-ion battery will be described below.

The positive electrode current collector 12 is not particularly limited, and examples thereof include metal foil.

Examples of the metal forming the metal foil include aluminum.

The positive electrode mixture layer 13 contains a positive electrode active material and may further contain other components.

Other components include, for example, solid electrolytes, conductive aids, binders, and the like.

The positive electrode active material is _{not particularly} limited as long _as it _is capable of intercalating and deintercalating lithium ions _. Ni6 _/10Co2 / _{10Mn2 /10} )O2 _{, Li} (Ni8 _{/ 10Co1} / _{10Mn1 /10} )O2 _, Li( _{Ni0.8Co0.15Al0.05} )O _2, Li(Ni1 _/6Co4 / _{6Mn1/ 6} )O2 _, Li(Ni1/ _{3Co1 / 3Mn1/3} )O2 _{, LiCoO4} , _{LiMn2O4 ,} LiNiO2 _, LiFePO ₄ , lithium sulfide, sulfur, and the like.

The solid electrolyte constituting the solid electrolyte layer 14 is not particularly limited as long as it is a material capable of conducting lithium ions. Examples thereof include oxide-based electrolytes and sulfide-based electrolytes.

The negative electrode mixture layer 15 contains a negative electrode active material and may further contain other components.

Other components include, for example, solid electrolytes, conductive aids, binders, and the like.

The negative electrode active material is not particularly limited as long as it is capable of intercalating and deintercalating lithium ions. materials and the like.

Examples of carbon materials include artificial graphite, natural graphite, hard carbon, and soft carbon.

The negative electrode current collector 16 is not particularly limited, but examples thereof include metal foil.

Examples of the metal forming the metal foil include copper and the like.
A case where the solid-state battery 10 is a solid-state lithium-ion battery will be described below.

A case where the solid-state battery 10 is an all-solid-state fluoride ion battery will be described below.

The positive electrode current collector 12 is not particularly limited, and examples thereof include metal foil.

Examples of the metal forming the metal foil include aluminum.

The positive electrode mixture layer 13 contains a positive electrode active material and may further contain other components.

Other components include, for example, solid electrolytes, conductive aids, binders, and the like.

The positive electrode active material is not particularly limited as long as it can occlude and release fluoride ions, but examples thereof include Pb, Cu, Sn, Bi and Ag.

The solid electrolyte forming the solid electrolyte layer 14 is not particularly limited as long as it is a material capable of conducting fluoride ions. Examples thereof include LaF ₃ and PbSnF ₄ .

The negative electrode mixture layer 15 contains a negative electrode active material and may further contain other components.

Other components include, for example, solid electrolytes, conductive aids, binders, and the like.

The negative electrode active material is not particularly limited as long as it can occlude and release fluoride ions, but examples thereof include CeF ₃ and PbF ₂ .

The negative electrode current collector 16 is not particularly limited, but examples thereof include metal foil.

Examples of the metal forming the metal foil include gold.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and the above embodiments may be changed as appropriate within the scope of the present invention.

Examples of the present invention will be described below, but the present invention is not limited to the examples.

[Example 1]
Under an ultra-low dew point environment with a dew point of −70° C., a portion of the positive electrode current collector 12 and the positive electrode mixture layer 13 are placed between the first sealing sheet 11A and the second sealing sheet 11B. , the solid electrolyte layer 14, the negative electrode mixture layer 15, and part of the negative electrode current collector 16 are sequentially arranged, and the first hot melt adhesive 18A, the insulating spacer 17, and the second hot melt and adhesive 18B were sequentially placed and sealed with a PPS film. At this time, the first sealing sheet 11A has the third hot-melt adhesive 21A formed in the region facing the positive electrode tab, and the second sealing sheet 11B has the region facing the negative electrode tab. , a fourth hot-melt adhesive 21B is formed (see FIG. 3). A member in which the positive electrode mixture layer 13 is formed on a part of the positive electrode current collector 12, and a member in which the negative electrode mixture layer 15 and the solid electrolyte layer 14 are sequentially laminated on a part of the negative electrode current collector 16. and used

Next, in an atmospheric environment, press cushioning materials 42 were fixed on the first sealing sheet 11A and under the second sealing sheet 11B with heat-resistant tapes 41 (see FIG. 4). It was heat-pressed under heat-press conditions to obtain a cell.

Pressure: 382MPa
Temperature: 150°C
Time: 30 seconds Heat-resistant tape 41: Kapton adhesive tape (manufactured by Teraoka Seisakusho)
Press cushioning material 42: 80mm x 80mm paco pad (manufactured by Pacotan Technology)
As a result, the insulating spacer 17 existed around the positive electrode mixture layer 13 and the solid electrolyte layer 14 . A third hot melt adhesive 21A is interposed between the first sealing sheet 11A and the positive electrode tab, and a fourth hot melt adhesive is interposed between the second sealing sheet 11B and the negative electrode tab. A melt adhesive 21B was interposed.

Next, after removing the PPS film, the heat-resistant tape 41 and the press cushioning material 42 from the cell in an atmospheric environment, tab leads were welded to the positive electrode tab and the negative electrode tab. In addition, the cell was sandwiched between aluminum laminate films for batteries, and after the two sides were welded, the cell was placed in a vacuum sealer and vacuum-sealed to produce an all-solid-state lithium ion battery.

Here, the members used when producing the solid lithium ion battery are as follows.

First sealing sheet 11A: 60 mm × 60 mm × 50 µm PET film (manufactured by Toray)
Second sealing sheet 11B: 60 mm × 60 mm × 50 µm PET film (manufactured by Toray)
Positive electrode current collector 12: 15 μm thick aluminum foil Positive electrode mixture layer 13: 50 m×50 mm×80 μm mixture of ternary lithium ion battery positive electrode material, sulfide solid electrolyte, conductive aid, and binder Solid electrolyte layer 14 : 54 m × 54 mm × 300 μm non-woven fabric manufactured by Mitsubishi Paper Mills, a sulfide-based solid electrolyte, and a binder mixture Negative electrode mixture layer 15: 54 m × 54 mm × 80 μm graphite, a sulfide-based solid electrolyte, a conductive aid, and a binder mixture Materials Negative electrode current collector 16: 10 μm thick copper foil Insulating spacer 17: 50 μm thick PET frame (manufactured by Toray)
First hot melt adhesive 18A: 50 μm thick PPa-F frame (manufactured by DNP)
Second hot melt adhesive 18B: 50 μm thick PPa-F frame (manufactured by DNP)
Third hot melt adhesive 21A: PPa-F hanger-shaped member with a thickness of 50 μm (manufactured by DNP)
Fourth hot melt adhesive 21B: PPa-F hanger-shaped member with a thickness of 50 μm (manufactured by DNP)

[Comparative Example 1]
Under an ultra-low dew point environment with a dew point of −70° C., a support plate made of stainless steel, a positive electrode current collector 12, a positive electrode mixture layer 13, a solid electrolyte layer 14, a negative electrode mixture layer 15, and a negative electrode A current collector 16 and a support plate made of stainless steel were sequentially laminated and sealed with a PPS film.

Next, the cell was pressed in an atmospheric environment while still sealed with the PPS film to obtain a cell.

Next, under an ultra-low dew point environment with a dew point of −70° C., after removing the PPS film from the cell, tab leads were welded to the positive and negative electrode tabs. In addition, the cell was sandwiched between aluminum laminate films for batteries, and after the two sides were welded, the cell was placed in a vacuum sealer and vacuum-sealed to produce an all-solid-state lithium ion battery.

Next, we evaluated the characteristics of the all-solid-state lithium-ion battery.

[Discharge capacity and specific capacity]
The all-solid lithium ion battery was assembled in a jig, restrained with a restraining pressure of 60 MPa, left at the measurement temperature (25° C.) for 1 hour, and then charged at a constant current of 8.4 mA to 4.2 V. Next, after leaving the all-solid-state lithium ion battery to stand for 15 minutes, it was subjected to constant current discharge to 2.6 V at a current value of 8.4 mA. Next, the above operation was repeated twice. Next, the confining pressure was lowered to 1 MPa and the above operation was performed. The discharge capacity during discharge at a confining pressure of 1 MPa was defined as the discharge capacity (mAh). Also, the discharge capacity was divided by the mass of the positive electrode active material of the all-solid lithium ion battery to obtain the specific capacity (mAh/g).

A current value at which discharge can be completed in 1 hour was defined as 1C with respect to the obtained discharge capacity.

[DC resistance]
After measuring the discharge capacity, the all-solid-state lithium ion battery was left at the measurement temperature (25 ° C.) for 1 hour, and then subjected to constant current charging at a charging rate of 0.2 C, and the charge level (SOC (State of Charge)). It was adjusted to 50% and left for 10 minutes. Next, pulse discharge was performed for 10 seconds at a discharge rate of 0.5 C, and the voltage was measured after 10 seconds of discharge. Then, with the horizontal axis representing the current value and the vertical axis representing the voltage, the voltage when the battery was discharged for 10 seconds was plotted against the discharge rate of 0.5C. Next, after leaving the all-solid lithium ion battery for 10 minutes, supplementary charging was performed to return the SOC to 50%, and the all-solid lithium ion battery was left for 10 minutes. Next, the above operation was performed at each discharge rate of 1.0C, 1.5C, 2.0C, 2.5C, and 3.0C, and the voltage when discharging for 10 seconds was calculated for each discharge rate. plotted. Then, the slope of the approximate straight line obtained from each plot by the method of least squares was defined as the DC resistance (mΩ).

[Coulomb efficiency]
The coulombic efficiency was obtained by dividing the discharge capacity at the time of discharge at a confining pressure of 1 MPa by the charge capacity.

Table 1 shows the evaluation results of the characteristics of the all-solid lithium ion battery.

From Table 1, the all-solid-state lithium ion battery of Example 1 has the same discharge capacity, specific capacity, DC resistance and coulombic efficiency as the all-solid-state lithium ion battery of Comparative Example 1, and is within a practical range. I understand.

10 solid battery 11A first sealing sheet 11B second sealing sheet 12 positive electrode current collector 13 positive electrode mixture layer 14 solid electrolyte layer 15 negative electrode mixture layer 16 negative electrode current collector 17 insulating spacer 18A first hot melt Adhesive 18B Second hot melt adhesive 21A Third hot melt adhesive 21B Fourth hot melt adhesive

Claims (3)

Between the first sealing sheet and the second sealing sheet, a part of the positive electrode current collector, a positive electrode mixture layer, a solid electrolyte layer, a negative electrode mixture layer, and a part of the negative electrode current collector and are stacked in order,
An insulating spacer is present around the solid electrolyte layer,
A first hot melt adhesive is interposed between the first sealing sheet and the insulating spacer,
A second hot melt adhesive is interposed between the second sealing sheet and the insulating spacer,
A third hot-melt adhesive is interposed between a region of the positive electrode current collector where the positive electrode mixture layer is not formed and the first sealing sheet,
A solid-state battery, wherein a fourth hot-melt adhesive is interposed between a region of the negative electrode current collector where the negative electrode mixture layer is not formed and the second sealing sheet. 2. The solid-state battery according to claim 1, wherein said insulating spacer also exists around said positive electrode mixture layer. A method for manufacturing the solid-state battery according to claim 1 or 2,
Between the first sealing sheet and the second sealing sheet, a part of the positive electrode current collector, the positive electrode mixture layer, the solid electrolyte layer, the negative electrode mixture layer, and the A part of the negative electrode current collector is sequentially arranged, and the first hot-melt adhesive, the insulating spacer, and the second hot-melt adhesive are sequentially arranged and then heat-pressed. including the process,
The first encapsulating sheet has the third hot-melt adhesive formed in a part of the region facing the region where the positive electrode mixture layer of the positive electrode current collector is not formed,
The second encapsulating sheet is a solid body in which the fourth hot-melt adhesive is formed in part of a region facing a region of the negative electrode current collector where the negative electrode mixture layer is not formed. Battery manufacturing method.

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