JP6988683B2 - All solid state battery - Google Patents

Description

The present disclosure relates to an all-solid-state battery having a high coating layer resistance at high temperatures.

An all-solid-state battery is a battery having a solid electrolyte layer between a positive electrode active material layer and a negative electrode active material layer, and has a simplified safety device as compared with a liquid-based battery having an electrolytic solution containing a flammable organic solvent. Easy to plan.

On the other hand, although it is not an all-solid-state battery, for example, Patent Document 1 discloses a negative electrode plate for a lithium secondary battery, which uses aluminum as a part of a metal foil and has a conductive carbon coating layer on the surface. In this lithium battery, the arrival of lithium ions on the aluminum foil during the charging reaction is suppressed by intercalating the coat layer, and when the lithium ions reach the aluminum foil and precipitate as metallic lithium, the aluminum alloy is used. This prevents the precipitation of metallic lithium dentrite.

Further, Patent Document 2 discloses a non-aqueous electrolyte secondary battery in which the negative electrode current collector additionally has a carbon coat layer.

Japanese Unexamined Patent Publication No. 2012-174577 Japanese Unexamined Patent Publication No. 2017-212110

A coat layer may be provided on the surface of the negative electrode current collector on the negative electrode active material layer side. By providing the coat layer, for example, when the temperature of the all-solid-state battery becomes high, the resistance of the all-solid-state battery can be increased. On the other hand, depending on the type of carbon material contained in the coat layer and the thickness of the coat layer, the resistance of the coat layer may be low at high temperatures. The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide an all-solid-state battery having a high resistance of a coat layer at a high temperature.

In order to solve the above problems, in the present disclosure, a negative electrode body having a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector, and a positive electrode current collector and the positive electrode current collector are used. The positive electrode body having the formed positive electrode active material layer and the solid electrolyte layer formed between the negative electrode active material layer and the positive electrode active material layer are provided, and the negative electrode current collector is at least partially aluminum. A metal foil containing the above metal foil and a coat layer formed on the negative electrode active material layer side of the metal foil are included, and the coat layer contains a spherical carbon material and a resin, and also contains a fibrous carbon material. However, the present invention provides an all-solid-state battery characterized in that the ratio of the thickness of the coat layer to the thickness of the metal foil is in the range of 0.26 to 1.05.

According to the present disclosure, it is possible to provide an all-solid-state battery having a high resistance of a coat layer at a high temperature.

It is a schematic sectional drawing which shows an example of the all-solid-state battery of this disclosure. It is a schematic cross-sectional view which shows the negative electrode body shown in FIG. It is a schematic cross-sectional view which shows the negative electrode body to compare. It is sectional drawing of the all-solid-state battery of Example 10. It is sectional drawing of the all-solid-state battery of the comparative example 13. It is a graph which shows the result of charge / discharge measurement of the all-solid-state battery obtained in Example 10 and Comparative Example 13. 6 is a graph comparing the energy densities (Wh / kg) of the all-solid-state batteries obtained in Example 10 and Comparative Example 13.

Hereinafter, the all-solid-state battery of the present disclosure will be described in detail.

The all-solid-state battery of the present disclosure includes a negative electrode body having a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector, and a positive electrode active body formed on the positive electrode current collector and the positive electrode current collector. The negative electrode current collector includes a positive electrode body having a material layer and a solid electrolyte layer formed between the negative electrode active material layer and the positive electrode active material layer, and the negative electrode current collector is a metal foil containing at least a part of aluminum. And the coating layer formed on the negative electrode active material layer side of the metal foil, the coating layer contains a spherical carbon material and a resin, and does not contain a fibrous carbon material. The ratio of the thickness of the coat layer to the thickness of the metal foil is in the range of 0.26 to 1.05.

The all-solid-state battery of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of the all-solid-state battery of the present disclosure. FIG. 2 is a schematic cross-sectional view showing the negative electrode body shown in FIG. 1, and FIG. 3 is a schematic cross-sectional view showing the negative electrode body to be compared.

As shown in FIG. 1, the all-solid-state battery 100 of the present disclosure includes a negative electrode body 30 including a negative electrode current collector 10 and a negative electrode active material layer 20, and a positive electrode body including a positive electrode current collector 50 and a positive electrode active material layer 60. It has a 70 and a solid electrolyte layer 40 formed between the negative electrode active material layer 20 and the positive electrode active material layer 60.

In the negative electrode body 30 shown in FIG. 1, the negative electrode current collector 10 includes an aluminum foil 12 and a coat layer 14 formed on the aluminum foil 12, as shown in FIG. The coat layer 14 contains a spherical carbon material 2, a resin 4, and an inorganic filler 6. The coat layer 14 does not contain the fibrous carbon material, and has an embodiment in which the spherical carbon material 2 and the inorganic filler 6 are dispersed and mixed in the resin 4. The negative electrode active material layer 20 is formed on the coat layer 14.

On the other hand, as shown in FIG. 3, the negative electrode body 30 to be compared is different from the negative electrode body 30 of the present disclosure, and the coat layer 14 contains the fibrous carbon material 2'.

Like the coat layer 14 shown in FIGS. 2 and 3, the coat layer having an embodiment in which the carbon materials are dispersed and mixed in the resin has an action of separating the carbon materials from each other due to the expansion of the resin with the temperature rise. In some cases, the effect of cutting the electron conduction bus can be obtained. As a result, the coat layer has PTC characteristics. PTC means Positive Temperature Coefficient, and refers to a characteristic in which resistance changes with a positive coefficient as the temperature rises. For example, when the temperature of the all-solid-state battery becomes high, the resistance of the coat layer can be increased by exhibiting good PTC characteristics of the coat layer.

However, in the coat layer in which the carbon material is fibrous like the coat layer 14 shown in FIG. 3, even if the resin expands, the carbon materials are not easily separated from each other, so that the action of cutting the electron conduction path is unlikely to occur. .. Therefore, for example, when the temperature of the all-solid-state battery becomes high, the coat layer may not exhibit good PTC characteristics, and the resistance of the coat layer may not be sufficiently increased. Further, depending on the thickness of the coat layer, the coat layer may not exhibit good PTC characteristics.

On the other hand, in the coat layer in which the carbon material is spherical like the coat layer 14 shown in FIG. 2, the carbon materials are easily separated from each other when the resin expands, so that the electron conduction path is cut. easy. Further, by setting the ratio of the thickness of the coat layer to the thickness of the metal foil within a specific range, the coat layer tends to exhibit good PTC characteristics. Therefore, for example, when the temperature of the all-solid-state battery becomes high, the resistance of the coat layer can be sufficiently increased. Therefore, according to the present disclosure, it is possible to provide an all-solid-state battery having a high resistance of the coat layer at a high temperature. Hereinafter, the all-solid-state battery of the present disclosure will be described for each configuration.

1. 1. Negative electrode body The negative electrode body in the present disclosure has a negative electrode current collector and a negative electrode active material layer.

(1) Negative electrode current collector The negative electrode current collector includes a metal foil and a coat layer formed on the metal foil.

a. Coat layer The coat layer contains a spherical carbon material and a resin, and does not contain a fibrous carbon material. Further, the coat layer may contain only a spherical carbon material as the carbon material.

Here, the spherical carbon material means a particulate carbon material having an aspect ratio (minor axis / major axis) of 1/100 or more, which is the ratio of the minor axis to the major axis. The spherical carbon material includes, for example, an elliptical spherical carbon material in addition to the true spherical carbon material. For the above aspect ratio, for at least 100 carbon materials, the minor axis / major axis of each carbon material was obtained by image analysis using, for example, a scanning electron microscope (SEM) or a transmission electron microscope (TEM), and the minor axis / major axis thereof was calculated and averaged. It means a value (arithmetic average value).

As the spherical carbon material, a material having an aspect ratio of 1/50 or more is preferable, and a material having an aspect ratio of 1/10 or more is particularly preferable. This is because the action of cutting the electron conduction path is particularly likely to occur.

The average primary particle size of the spherical carbon material is, for example, in the range of 10 nm to 20 μm. Here, as the average primary particle diameter, for example, 30 or more primary particle diameters (average of minor axis and major axis) are measured based on image analysis using an electron microscope such as SEM (scanning electron microscope), and they are measured. The value obtained as the arithmetic mean of can be adopted.

Examples of the spherical carbon material include furnace black, carbon black, activated carbon, carbon, carbon fiber, graphite and the like. Of these, furnace black, carbon black, carbon, graphite and the like are preferable. In particular, furnace black, carbon black and the like are preferable. This is because the action of cutting the electron conduction path is particularly likely to occur. The content of the spherical carbon material in the coat layer is, for example, in the range of 5% by volume to 95% by volume, and more preferably in the range of 5% by volume to 90% by volume.

The fibrous carbon material means a carbon material having an aspect ratio (minor axis / major axis) of less than 1/100, which is the ratio of the minor axis to the major axis. For the above aspect ratio, for at least 100 carbon materials, the minor axis / major axis of each carbon material was obtained by image analysis using, for example, a scanning electron microscope (SEM) or a transmission electron microscope (TEM), and the minor axis / major axis thereof was calculated and averaged. It means a value (arithmetic average value).

Examples of the fibrous carbon material include gas phase grown carbon fibers (VGCF), carbon nanotubes, carbon nanofibers and the like.

Examples of the resin contained in the coat layer include thermoplastic resins and the like. The content of the resin in the coat layer is, for example, in the range of 5% by volume to 90% by volume.

The coat layer may further contain an inorganic filler as in the coat layer 14 shown in FIG. In an all-solid-state battery, a restraining pressure is usually applied along the thickness direction, so that the resin may be deformed or flowed under the influence of the restraining pressure, and good PTC characteristics may not be exhibited. This is because by adding a hard inorganic filler, good PTC characteristics can be exhibited even when affected by the restraining pressure.

Examples of the inorganic filler include metal oxides and metal nitrides. Examples of the metal oxide include alumina, zirconia, silica and the like, and examples of the metal nitride include silicon nitride. The average particle size (D ₅₀ ) of the inorganic filler is, for example, in the range of 50 nm to 5 μm. The content of the inorganic filler in the coat layer is, for example, 50% by volume or more. On the other hand, the content of the inorganic filler in the coat layer is, for example, 85% by volume or less.

The ratio of the thickness of the coat layer (thickness of the coat layer / thickness of the metal foil) to the thickness of the metal foil described later is in the range of 0.26 to 1.05. The ratio of the thickness of the coat layer to the thickness of the metal foil is preferably in the range of 0.53 to 0.78. This is because if the ratio of the thickness of the coat layer is too small, the resistance may not be sufficiently increased even if the resin expands. Further, if the ratio of the thickness of the coat layer is too large, the resistance may not be sufficiently increased.

The thickness of the coat layer is preferably in the range of 3.9 μm to 15.7 μm, and more preferably in the range of 8.0 μm to 11.7 μm. This is because if it is too thin, the resistance may not be sufficiently increased even if the resin expands. Further, even if it is too thick, the resistance may not be sufficiently increased.

The method for forming the coat layer is not particularly limited, and examples thereof include a method of applying a slurry containing a spherical carbon material and a resin. The slurry may further contain other conductive materials or inorganic fillers.

b. Metal Foil The metal foil in the present disclosure contains at least a part of aluminum.

As the metal foil, in addition to the aluminum foil, a metal foil such as SUS, Cu, Ni, Fe, Ti, Co, or Zn, a metal such as SUS, Cu, Ni, Fe, Ti, Co, or Zn, and Al. Examples thereof include a foil using the clad material of the above, and a foil having a metal surface coated with Al. As the metal foil, an aluminum foil is preferable. This is because it is lightweight, has excellent conductivity, and is advantageous in terms of cost and availability.

Further, it is preferable to appropriately select the thickness and shape of the metal foil according to the use of the all-solid-state battery and the like. The thickness of the metal foil is, for example, in the range of 5 μm to 20 μm, and more preferably in the range of 10 μm to 15 μm.

(2) Negative electrode active material layer The negative electrode active material layer in the present disclosure is a layer containing at least a negative electrode active material, and further contains at least one of a solid electrolyte, a conductive material, and a binder, if necessary. You may be doing it.

The negative electrode active material is not particularly limited as long as it can occlude and release metal ions, and examples thereof include carbon active materials, metal active materials, and oxide active materials. The shape of the negative electrode active material can be, for example, particles. The content of the negative electrode active material in the negative electrode active material layer is not particularly limited, and may be, for example, 40% by mass or more and 100% by mass or less.

Examples of the solid electrolyte include an inorganic solid electrolyte such as a sulfide solid electrolyte. Examples of the shape of the solid electrolyte include particles. The average particle size (D ₅₀ ) of the particulate solid electrolyte is preferably in the range of, for example, 0.1 μm to 50 μm. The weight ratio (active material / solid electrolyte) of the negative electrode active material and the solid electrolyte in the negative electrode active material layer is, for example, in the range of 30/70 to 85/15.

Examples of the conductive material include carbon materials such as acetylene black (AB), Ketjen black (KB), gas phase growth carbon fiber (VGCF), carbon nanotube (CNT), and carbon nanofiber (CNF). can. By adding the conductive material, the electron conductivity of the negative electrode active material layer can be improved. Examples of the binder include polyvinylidene fluoride (PVDF), butylene rubber (BR), styrene-butadiene rubber (SBR) and the like. By adding a binder, the moldability of the negative electrode active material layer can be improved.

The thickness of the negative electrode active material layer is, for example, in the range of 1 μm to 100 μm.

2. 2. Positive electrode body The positive electrode body in the present disclosure has a positive electrode current collector and a positive electrode active material layer.

(1) Positive electrode current collector The positive electrode current collector has a function of collecting current from the positive electrode active material layer.

Examples of the material of the positive electrode current collector include SUS, Ni, Cr, Au, Pt, Al, Fe, Ti, Zn and the like. A coat layer of Ni, Cr, C or the like may be formed on the surface of the positive electrode current collector. The coat layer may be, for example, a plating layer or a thin-film deposition layer. It is preferable to appropriately select the thickness, shape, etc. of the positive electrode current collector according to the application of the all-solid-state battery.

(2) Positive Electrode Active Material Layer The positive electrode active material layer is a layer containing at least a positive electrode active material, and may contain at least one of a solid electrolyte, a conductive material, and a binder, if necessary. good.

The type of the positive electrode active material is not particularly limited, and examples thereof include an oxide active material and a sulfide active material. The shape of the positive electrode active material can be, for example, particles. The content of the positive electrode active material in the positive electrode active material layer is not particularly limited, and may be, for example, 40% by mass or more and 99% by mass or less.

The solid electrolyte, the conductive material, and the binder used for the positive electrode active material layer are the same as those described in the above item “1. Negative electrode body (2) Negative electrode active material layer”. The thickness of the positive electrode active material layer is, for example, in the range of 1 μm to 100 μm.

3. 3. Solid Electrolyte Layer The solid electrolyte layer in the present disclosure is a layer formed between a positive electrode active material layer and a negative electrode active material layer. The solid electrolyte layer is a layer containing at least a solid electrolyte, and may further contain a binder, if necessary. The solid electrolyte layer preferably contains a sulfide solid electrolyte. The solid electrolyte and the binder are the same as those described in the above item “1. Negative electrode body (2) Negative electrode active material layer”.

The proportion of the solid electrolyte contained in the solid electrolyte layer is, for example, in the range of 10% by volume to 100% by volume. The thickness of the solid electrolyte layer is, for example, in the range of 0.1 μm to 1000 μm. Moreover, as a method of forming a solid electrolyte layer, for example, a method of compression molding a solid electrolyte and the like can be mentioned.

4. All-solid-state battery In the all-solid-state battery of the present disclosure, any battery case such as a SUS battery case can be used. The all-solid-state battery of the present disclosure may be a primary battery or a secondary battery, but is preferably a secondary battery. This is because it can be repeatedly charged and discharged and is useful as an in-vehicle battery, for example. Examples of the shape of the all-solid-state battery include a coin type, a laminated type, a cylindrical type, a square type, and the like.

The present disclosure is not limited to the above embodiment. The above embodiment is an example, and any one having substantially the same structure as the technical idea described in the claims of the present disclosure and having the same effect and effect is the present invention. Included in the technical scope of the disclosure.

The present disclosure will be described in more detail with reference to Examples below.

[Example 1]
As a carbon material, furnace black (manufactured by Tokai Carbon) having an average primary particle size of 66 nm was prepared. PVDF (KF polymer L # 9130 manufactured by Kureha Corporation) was prepared as a resin.

The carbon material and the resin were mixed in a volume ratio of carbon material: resin = 92: 8. Then, the obtained mixture and N-methyl-2-pyrrolidone (NMP) were placed in a container and kneaded using an ultrasonic homogenizer to obtain a slurry for a coat layer.

Using an applicator, the coat layer slurry was applied onto an aluminum foil (metal foil) having a thickness of 15 μm by the blade method. This was dried at 100 ° C. for 1 hour in a stationary drying oven to form a 3.9 μm-thick coat layer on the aluminum foil. As a result, an aluminum foil with a coated layer was produced as a negative electrode current collector.

[Examples 2 to 9]
In Examples 2 to 9, the thicknesses of 5.0 μm, 6.1 μm, 6.7 μm, 8.0 μm, 10.1 μm, 11.7 μm, 13.8 μm, and 15.7 μm were set when forming the coat layer. An aluminum foil with a coated layer was produced as a negative electrode current collector in the same manner as in Example 1.

[Comparative Example 1]
Except for the fact that the carbon material and the resin were mixed in a volume ratio of carbon material: resin = 20:80 when the slurry for the coat layer was obtained, and the thickness was 0.3 μm when the coat layer was formed. An aluminum foil with a coated layer was produced as a negative electrode current collector in the same manner as in Example 1.

[Comparative Example 2 to Comparative Example 5]
Comparative Examples 2 to 5 are the same as in Example 1 except that the thicknesses of the coat layer are 1.5 μm, 2.1 μm, 3.0 μm, and 17.9 μm, respectively. An aluminum foil with a coated layer was produced as a negative electrode current collector.

[Comparative Example 6]
As a carbon material, a mixture of furnace black (manufactured by Tokai Carbon) having an average primary particle size of 66 nm and VGCF in a volume ratio of furnace black: VGCF = 73: 27 was prepared. PVDF (KF polymer L # 9130 manufactured by Kureha Corporation) was prepared as a resin.

The carbon material and the resin were mixed in a volume ratio of furnace black: VGCF: resin = 67: 25: 8. Then, the obtained mixture and N-methyl-2-pyrrolidone (NMP) were placed in a container and kneaded using an ultrasonic homogenizer to obtain a slurry for a coat layer.

Using an applicator, the coat layer slurry was applied onto an aluminum foil (metal foil) having a thickness of 15 μm by the blade method. This was dried at 100 ° C. for 1 hour in a stationary drying oven to form a coat layer having a thickness of 2.4 μm on the aluminum foil. As a result, an aluminum foil with a coated layer was produced as a negative electrode current collector.

[Comparative Examples 7 to 12]
In Comparative Examples 7 to 12, the comparative examples were made except that the thicknesses were 4.5 μm, 6.0 μm, 8.0 μm, 11.5 μm, 20.5 μm, and 22.0 μm when the coat layer was formed. Similar to No. 6, an aluminum foil with a coated layer was produced as a negative electrode current collector.

[Evaluation (resistance measurement)]
The negative electrode current collectors obtained in Examples 1 to 9 and Comparative Examples 1 to 12 ^{were punched into a circle (1 cm 2} ) having a diameter of 11.28 mm, sandwiched between columnar terminals having the same diameter, and the terminals were constrained at 10 MPa. .. Each terminal sandwiching the negative electrode current collector was placed in a constant temperature bath, heated to 25 ° C., and then held for 1 hour. After that, a constant current of 1 mA was applied between the terminals, the voltage between the terminals was measured, and the resistance value was calculated. Further, each terminal sandwiching the negative electrode current collector was installed in a constant temperature bath, heated to 200 ° C., and then held for 1 hour. After that, a constant current of 1 mA was applied between the terminals, the voltage between the terminals was measured, and the resistance value was calculated. The results are shown in Table 1.

As shown in Table 1, in Examples 1 to 9, the DC resistance after heating at 200 ° C. for 1 hour was larger than that in Comparative Examples 1 to 12.

[Example 10]
(Manufacturing of negative electrode body)
An aluminum foil with a coated layer was produced as a negative electrode current collector in the same manner as in Example 5.

Graphite (manufactured by Mitsubishi Chemical Corporation) was prepared as the negative electrode active material.

The _{starting materials were Li 2} S (manufactured by Nippon Chemical Industrial Co., Ltd.), P ₂ S ₅ (manufactured by Aldrich) and LiBr (manufactured by Nippoh Chemicals). Each material was mixed in an agate mortar for 5 minutes so that the molar ratio was 20 LiBr · 80 (0.75Li ₂ S · 0.25P ₂ S _5). 2 g of the mixture is put into a container of a planetary ball mill (45 cc, _{manufactured by ZrO 2} ), dehydrated heptane (water content of 30 ppm or less, 4 g) is put into it, and ZrO ₂ balls (φ = 5 mm, 53 g) are put into the container. Was completely sealed. This container was attached to a planetary ball mill machine (P7 manufactured by Fritsch), and mechanical milling was performed for 2 hours at a base rotation speed of 500 rpm. Then, heptane was removed by drying at 110 ° C. for 1 hour to obtain a sulfide solid electrolyte (sulfide glass).

Negative electrode active material, sulfide solid electrolyte, binder (PVDF), conductive agent (VGCF), negative electrode active material: sulfide solid electrolyte: binder: conductive agent = 100: 77.6 The mixture was mixed in a weight ratio of 2: 8. Then, the obtained mixture and the dispersion medium (butyl acetate) were placed in a container and kneaded using an ultrasonic homogenizer to obtain a slurry for a negative electrode.

Using an applicator, the negative electrode slurry was applied onto the coated layer of the coated aluminum foil by the blade method. This was dried on a hot plate at 100 ° C. for 30 minutes to form a negative electrode active material layer on the coated layer of the aluminum foil with a coated layer.

A laminated body in which the aluminum foil with a coat layer and the negative electrode active material layer are laminated in the order of the negative electrode current collector, the coat layer, and the negative electrode active material layer is set in a roll press machine, and the press line pressure is 20 kN / cm and the press temperature is 25. Pressing at ° C to obtain a negative electrode body.

(Preparation of positive electrode body)
Lithium nickel cobalt manganate (Li _{1 + x} Ni _1/3 Co _1/3 Mn _1/3 O ₂ ) was prepared as the positive electrode active material. A sulfide solid electrolyte similar to the sulfide solid electrolyte used for producing the negative electrode body was prepared.

A coat layer (average thickness 10 nm) of _{LiNbO 3} was formed on the surface of the positive electrode active material by using a rolling flow coating device (MP01, manufactured by Paulek Co., Ltd.).
Then, the positive electrode active material, the sulfide solid electrolyte, the binder (PVDF), and the conductive agent (VGCF) are used, and the positive electrode active material: sulfide solid electrolyte: binder: conductive agent = 100: 12. The mixture was mixed in a weight ratio of: 1.5: 1.5. Then, the obtained mixture and the dispersion medium (butyl acetate) were placed in a container and kneaded using an ultrasonic homogenizer to obtain a slurry for a positive electrode.

Using an applicator, the positive electrode slurry was applied onto an aluminum foil as a positive electrode current collector by the blade method. This was dried on a hot plate at 100 ° C. for 30 minutes to form a positive electrode active material layer on the positive electrode current collector.

A laminated body in which a positive electrode current collector and a positive electrode active material layer were laminated in this order was set in a roll press machine and pressed at a press line pressure of 20 kN / cm and a press temperature of 25 ° C. to obtain a positive electrode body.
The positive electrode body and the negative electrode body were manufactured so that the area of the positive electrode body was smaller than the area of the negative electrode body. The area ratio of the positive electrode body and the negative electrode body was 1.00: 1.08.

(Preparation of solid electrolyte layer)
A sulfide solid electrolyte similar to the sulfide solid electrolyte used for producing the negative electrode body and the positive electrode body was prepared.

An electrolyte mixture containing a sulfide solid electrolyte, a dispersion medium (heptane), and a binder (a heptane solution of a BR-based binder, 5% by mass) was placed in a polypropylene (PP) container. This is stirred with an ultrasonic disperser (manufactured by SMT, model: UH-50) for 30 seconds, and shaken with a shaker (manufactured by Shibata Scientific Technology, model: TTM-1) for 30 minutes. A solid electrolyte slurry was prepared.

Using an applicator, the solid electrolyte slurry was applied onto the aluminum foil as a release sheet by the blade method. This was dried on a hot plate at 100 ° C. for 30 minutes to obtain a release sheet and a transfer sheet having a solid electrolyte layer.

(Manufacturing of all-solid-state battery)
The positive electrode body and the negative electrode body having the solid electrolyte layer were laminated so that the positive electrode active material layer of the positive electrode body and the solid electrolyte layer faced each other. This laminate was set in a flat uniaxial press machine and pressed at a press line pressure of 200 MPa and a press temperature of 120 ° C. for 1 minute. This gave an all-solid-state battery. A cross-sectional photograph of the all-solid-state battery is shown in FIG.

[Comparative Example 13]
A negative electrode body, a positive electrode body, and a solid electrolyte layer were prepared in the same manner as in Example 10, except that a copper foil (metal foil) having a thickness of 15 μm was prepared as the negative electrode current collector instead of the aluminum foil with a coated layer. did. Then, in the same manner as in Example 10, the laminated body in which these were laminated was pressed to obtain an all-solid-state battery. A cross-sectional photograph of the all-solid-state battery is shown in FIG.

[Evaluation (charge / discharge measurement)]
Charge / discharge measurements were performed using the all-solid-state batteries obtained in Example 10 and Comparative Example 13. First, as conditioning, it was adjusted to 4.55V by CCCV charging at 0.1C rate, and then 3.0V by CCCV discharge at 1C rate. In the subsequent charge / discharge, CCCV was charged / discharged at a 1/3 C rate. The voltage range was 3.0-4.35V and the measurement temperature was 25C. The results are shown in FIG.

As shown in FIG. 6, the all-solid-state battery obtained in Example 10 has the same performance as the all-solid-state battery obtained in Comparative Example 13. That is, an all-solid-state battery using an aluminum foil with a coated layer, which is lighter than a copper foil, as a negative electrode current collector has the same performance as an all-solid-state battery using a copper foil as a negative electrode current collector. FIG. 7 shows the results of comparing the energy density (Wh / kg) of the battery per unit weight of the negative electrode current collector between the aluminum foil with the coated layer and the copper foil.

30 ... Negative electrode body 10 ... Negative electrode current collector 12 ... Aluminum foil 14 ... Coat layer 2 ... Spherical carbon material 2'... Fibrous carbon material 4 ... Resin 6 ... Inorganic filler

Claims (1)

A negative electrode body having a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector, and a positive electrode body having a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector. A solid electrolyte layer formed between the negative electrode active material layer and the positive electrode active material layer is provided.
The negative electrode current collector includes a metal foil containing at least a part of aluminum and a coat layer formed on the negative electrode active material layer side of the metal foil.
The coat layer contains a spherical carbon material and a thermoplastic resin , and does not contain a fibrous carbon material.
The spherical carbon material is furnace black having an average primary particle size of 10 nm or more and 66 nm or less.
The content of the thermoplastic resin in the coat layer is 5% by volume or more and 8% by volume or less, and the content of the spherical carbon material is 92% by volume or more and 95% by volume or less.
An all-solid-state battery characterized in that the ratio of the thickness of the coat layer to the thickness of the metal foil is in the range of 0.26 to 1.05.

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