JP7643302B2 - Stacked battery - Google Patents

Description

This disclosure relates to a stacked battery.

Stacked batteries in which the sides of a battery stack are covered with a resin layer are known. For example, Patent Document 1 discloses an all-solid-state battery that includes a battery stack including two or more unit cells each formed by stacking a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer in that order, and a resin layer that covers the battery stack.

JP 2020-004529 A

From the viewpoint of structural stability of the battery, good adhesion of the resin layer (insulating layer) is required. This disclosure has been made in consideration of the above-mentioned circumstances, and has as its main objective the provision of a stacked battery having good adhesion between the insulating layer and the battery stack.

In order to solve the above problem, the present disclosure provides a stacked battery including a battery stack having a positive electrode active material layer, a negative electrode active material layer, a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer, a positive electrode current collector that collects current from the positive electrode active material layer, and a negative electrode current collector that collects current from the negative electrode active material layer, and an insulating layer that covers the side surface of the battery stack, in which, in a cross-sectional view of the stacking direction of the battery stack, the solid electrolyte layer, the positive electrode current collector, and the negative electrode current collector each have an extension portion located outside the positive electrode active material layer and the negative electrode active material layer, and in the cross-sectional view, the extension portion of the solid electrolyte layer, the extension portion of the positive electrode current collector, and the extension portion of the negative electrode current collector have the same end surface position.

According to the present disclosure, the solid electrolyte layer, the positive electrode current collector, and the negative electrode current collector each have an extension portion, resulting in a stacked battery with good adhesion to the insulating layer. Furthermore, because the end faces of each extension portion are positioned at the same position, reduction in volumetric energy density due to the extension portions can be suppressed.

The present disclosure has the effect of providing a stacked battery with good adhesion between the insulating layer and the battery stack.

FIG. 1 is a schematic cross-sectional view illustrating a stacked battery according to the present disclosure. FIG. 2 is a schematic cross-sectional view illustrating a battery stack according to the present disclosure. 2 is a schematic cross-sectional view illustrating an example of a cross-sectional shape of an end surface of an active material layer in the present disclosure. FIG. 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a stacked battery in the present disclosure. 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a stacked battery in the present disclosure.

The stacked battery of this disclosure will be described in detail below with reference to the drawings. Each of the drawings shown below is a schematic illustration, and the size and shape of each part are appropriately exaggerated to make it easier to understand. In addition, hatching showing the cross section of a member is appropriately omitted in each drawing.

Figure 1 is a schematic cross-sectional view illustrating a stacked battery in the present disclosure. Also, Figure 2 is a schematic cross-sectional view illustrating a battery stack in the present disclosure, and is an enlarged view of a part of the battery stack in Figure 1. The stacked battery 100 shown in Figure 1 has a power generation unit 10a having a positive electrode active material layer 1a, a negative electrode active material layer 2a, and a solid electrolyte layer 3a arranged between the positive electrode active material layer 1a and the negative electrode active material layer 2a. Also, a positive electrode current collector 4 is arranged on the surface of the positive electrode active material layer 1a opposite to the solid electrolyte layer 3a, and a negative electrode current collector 5 is arranged on the surface of the negative electrode active material layer 2a opposite to the solid electrolyte layer 3a.

The stacked battery 100 shown in FIG. 1 includes a generating unit 10b having a positive electrode active material layer 1b, a negative electrode active material layer 2b, and a solid electrolyte layer 3b disposed between the positive electrode active material layer 1b and the negative electrode active material layer 2b. A positive electrode current collector 4 is disposed on the surface of the positive electrode active material layer 1b opposite the solid electrolyte layer 3b, and a negative electrode current collector 5 is disposed on the surface of the negative electrode active material layer 2b opposite the solid electrolyte layer 3b. The generating unit 10a and the generating unit 10b share the negative electrode current collector 5, and are connected in parallel. The stacked battery 100 also includes an insulating layer 21 that covers the side surface of the battery stack 20.

As shown in Figs. 1 and 2, in a cross-sectional view of the stacking direction of the battery stack 20, the solid electrolyte layer 3 (3a, 3b), the positive electrode collector 4, and the negative electrode collector 5 each have an extension 6 located outside (outside in a direction perpendicular to the stacking direction) the positive electrode active material layer 1 and the negative electrode active material layer 2. Specifically, the positive electrode collector 4 shown in Fig. 2 has an extension 6 located outside the adjacent positive electrode active material layer 1a. The solid electrolyte layer 3a shown in Fig. 2 has an extension 6 located outside the adjacent positive electrode active material layer 1a and the negative electrode active material layer 2a. Also, the negative electrode collector 5 shown in Fig. 2 has an extension 6 located outside the adjacent negative electrode active material layer 2a.

As shown in FIG. 2, the end faces of the extension 6 in the solid electrolyte layer 3, the extension 6 in the positive electrode current collector 4, and the extension 6 in the negative electrode current collector 5 are positioned at the same position. Note that in FIG. 1, the end faces of the extensions 6 are positioned at the same position on both sides of the cross section (both sides in the left-right direction of the paper), but the end faces of the extensions 6 may be positioned at the same position on only one side.

According to the present disclosure, the solid electrolyte layer, the positive electrode collector, and the negative electrode collector each have an extension portion, resulting in a stacked battery with good adhesion between the insulating layer and the battery stack. Specifically, the solid electrolyte layer, the positive electrode collector, and the negative electrode collector each have an extension portion, so that the insulating layer can contact the end faces of the active material layers (positive electrode active material layer, negative electrode active material layer), the upper surface of the extension portion, and the lower surface of the extension portion. As a result, the contact area between the battery stack and the insulating layer is improved, and the adhesiveness between the insulating layer and the battery stack is good. In addition, because the adhesiveness between the insulating layer and the battery stack is good, peeling of the insulating layer can be suppressed, and as a result, the occurrence of an internal short circuit is also suppressed.

Furthermore, according to the present disclosure, the end faces of each extension are positioned at the same position, so that the reduction in volumetric energy density due to the extensions can be suppressed. Since the extensions are not parts that contribute to the charging and discharging of the battery, for example, if the end faces of each extension are not positioned at the same position, the volumetric energy density of the stacked battery is likely to decrease. Furthermore, in stacked batteries, there is a risk of a phase difference occurring in the stacking direction due to stacking misalignment occurring when stacking each layer or coating misalignment occurring when forming each layer. In contrast, in the present disclosure, the end faces of each extension are positioned at the same position, so that the occurrence of a phase difference can be suppressed.

The battery stack in the present disclosure includes a positive electrode active material layer, a negative electrode active material layer, a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer, a positive electrode current collector that collects current from the positive electrode active material layer, and a negative electrode current collector that collects current from the negative electrode active material layer. Details of each component will be described later.

In a cross-sectional view of the stacking direction of the battery stack, the solid electrolyte layer, the positive electrode collector, and the negative electrode collector each have an extension located outside the positive electrode active material layer and the negative electrode active material layer. In the cross-sectional view, the extension in the solid electrolyte layer, the extension in the positive electrode collector, and the extension in the negative electrode collector have the same end surface position. Here, "the end surface positions are equal" includes not only the case where the end surface positions of the extensions in the solid electrolyte layer, the positive electrode collector, and the negative electrode collector match (are flush) in the cross-sectional view, but also the case where they are approximately flush. When the end surface positions of the extensions are approximately flush, the maximum difference in the end surface positions of the extensions is preferably 500 μm or less.

As shown in FIG. 2, the distance from the position of the end face of the positive electrode active material layer 1 to the position of the end face of the extension portion 6 is defined as the width _W1 of the extension portion 6. The value of _W1 is not particularly limited, but may be, for example, greater than 500 μm, 1 mm or more, or 3 mm or more. On the other hand, the value of _W1 is, for example, 10 mm or less. Also, as shown in FIG. 2, the distance from the position of the end face of the negative electrode active material layer 2 to the position of the end face of the extension portion 6 is defined as the width _W2 of the extension portion 6. The preferred range of _W2 is the same as the preferred range of _W1 described above.

The cross-sectional shape of the end face of the active material layer is not particularly limited. For example, as shown in FIG. 2, the cross-sectional shape of the end face of the positive electrode active material layer 1 may be linear. In FIG. 2, the cross-sectional shape of the end face of the negative electrode active material layer 2 is also linear. For example, as shown in FIG. 3(a), the cross-sectional shape of the end face of the positive electrode active material layer 1 may be curved, such as an arc. In FIG. 3(a), the cross-sectional shape of the end face of the negative electrode active material layer 2 is also arc-shaped. For example, as shown in FIG. 3(b), the cross-sectional shape of the end face of the positive electrode active material layer 1 may be zigzag. In FIG. 3(b), the cross-sectional shape of the end face of the negative electrode active material layer 2 is also zigzag.

In addition, the battery stack in the present disclosure may have only one power generation unit, or may have two or more power generation units, when a set of a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer is taken as a power generation unit. When the battery stack has two or more power generation units, the power generation units may be connected in series or in parallel. In addition, the battery stack 20 shown in FIG. 1 has a power generation element 10a and a power generation element 10b arranged on both sides of the negative electrode current collector 5. On the other hand, although not shown in particular, two power generation elements may be arranged on both sides of the positive electrode current collector. In this case, the positive electrode active material layer, the positive electrode current collector, the negative electrode active material layer, and the negative electrode current collector in FIG. 1 are replaced with the negative electrode active material layer, the negative electrode current collector, the positive electrode active material layer, and the positive electrode current collector, respectively.

(1) Positive Electrode Active Material Layer The positive electrode active material layer in the present disclosure is a layer containing at least a positive electrode active material. The positive electrode active material layer may contain at least one of a solid electrolyte, a conductive material, and a binder, as necessary.

The positive electrode active material is not particularly limited, and examples thereof include oxide active materials and sulfur-based active materials. Examples of oxide active materials include rock salt layered active materials such as _LiCoO2 , _LiMnO2 , _LiNiO2 , _LiVO2 , and LiNi1 _/3Co1 / _{3Mn1 / 3O2,} spinel active materials such as _LiMn2O4 , _Li4Ti5O12 , and _{Li ( Ni0.5Mn1.5 ) O4 ,} and olivine active materials such as _LiFePO4 , _LiMnPO4 , _LiNiPO4 , and _LiCoPO4 . As the oxide active material, a LiMn spinel active material represented by Li1 _{+xMn2 -xyMyO4 (} wherein M is at least one of Al, Mg, Co, Fe, Ni and Zn, and 0<x+y<2) or lithium titanate may be used.

In addition, a coating layer containing a Li ion conductive oxide may be formed on the surface of the oxide active material. This is because it is possible to suppress the reaction between the oxide active material and the solid electrolyte. Examples of Li ion conductive oxides include LiNbO ₃ , Li ₄ Ti ₅ O ₁₂ , and Li ₃ PO ₄ .

Examples of the solid electrolyte include inorganic solid electrolytes. Examples of the inorganic solid electrolyte include sulfide solid electrolytes, oxide solid electrolytes, nitride solid electrolytes, and halide solid electrolytes. Examples of the conductive material include carbon materials and metal materials. Examples of the carbon material include carbon black such as acetylene black (AB) and ketjen black (KB), and fibrous carbon materials such as vapor grown carbon fiber (VGCF), carbon nanotubes (CNT), and carbon nanofibers (CNF). Examples of the binder include fluorine-based resins such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), and rubber-based resins such as acrylate butadiene rubber (ABR) and styrene butadiene rubber (SBR). The thickness of the positive electrode active material layer is, for example, 0.1 μm or more and 1000 μm or less.

(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. The negative electrode active material layer may contain at least one of a solid electrolyte, a conductive material, and a binder, as necessary. The solid electrolyte, the conductive material, and the binder are the same as those described in "(1) Positive electrode active material layer".

Examples of the negative electrode active material include metal active material and carbon active material. Examples of the metal active material include In, Al, Si, and Sn. On the other hand, examples of the carbon active material include mesocarbon microbeads (MCMB), highly oriented pyrolytic graphite (HOPG), hard carbon, and soft carbon. The thickness of the negative electrode active material layer is, for example, 0.1 μm or more and 1000 μm or less.

(3) Solid electrolyte layer The solid electrolyte layer in the present disclosure is a layer disposed between the positive electrode active material layer and the negative electrode active material layer, and contains at least a solid electrolyte. The solid electrolyte layer may contain a binder as necessary. The binder is the same as that described in "(1) Positive electrode active material layer". The thickness of the solid electrolyte layer is, for example, 0.1 μm or more and 1000 μm or less.

(4) Positive electrode current collector and negative electrode current collector The battery stack in the present disclosure has a positive electrode current collector that collects the positive electrode active material layer and a negative electrode current collector that collects the negative electrode active material layer. Examples of the positive electrode current collector include Al, SUS, and Ni. Examples of the negative electrode current collector include Cu, SUS, and Ni. Examples of the shape of the positive electrode current collector and the negative electrode current collector include a foil shape, a mesh shape, and a porous shape.

2. Insulating layer The insulating layer in the present disclosure is a layer that covers the side surface of the battery stack described above. Examples of the material of the insulating layer include resins. Examples of the resin include urethane acrylate resins, epoxy resins, and olefin resins. The resin may be a thermoplastic resin or a curable resin (cured product). The curable resin may be a thermosetting resin or an ultraviolet curable resin. The insulating layer may have an adhesive portion such as a tape on the surface facing the battery stack.

From the viewpoint of insulation, the insulating layer may cover the side surface of either the positive electrode (positive electrode current collector and positive electrode active material layer) or the negative electrode (negative electrode current collector and negative electrode active material layer). On the other hand, the insulating layer may cover the side surfaces of all the components of the battery stack, as shown in FIG. 1. In this case, it is possible to prevent the components from slipping off.

3. Stacked battery The stacked battery in the present disclosure is typically a lithium secondary battery. The use of the stacked battery is not particularly limited, but examples thereof include power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric vehicles (BEVs), gasoline-powered vehicles, and diesel-powered vehicles. In particular, the stacked battery is preferably used as a driving power source for hybrid electric vehicles, plug-in hybrid electric vehicles, or electric vehicles. The stacked battery in the present disclosure may also be used as a power source for moving objects other than vehicles (e.g., railways, ships, and aircraft), and may also be used as a power source for electrical appliances such as information processing devices.

The method for manufacturing the stacked battery in the present disclosure is not particularly limited. FIG. 4 is a schematic cross-sectional view illustrating a method for manufacturing the stacked battery in the present disclosure. First, as shown in FIG. 4(a), a precursor member X having a power generation unit 10a and a positive electrode collector 4 on one side of the negative electrode collector 5 and a power generation unit 10b and a positive electrode collector 4 on the other side of the negative electrode collector 5 is prepared. Next, as shown in FIG. 4(b), both ends of the precursor member X are cut. Examples of methods for cutting both ends of the precursor member X include a method using a blade and a method using a laser. Next, as shown in FIG. 4(c), the end faces of the positive electrode active material layer 1 (1a, 1b) and the negative electrode active material layer 2 (2a, 2b) are cut to form an extension portion 6, thereby obtaining a battery stack 20. Examples of methods for cutting the end faces include irradiation of a laser such as a femtosecond laser and mechanical processing such as a file. Next, as shown in FIG. 4(d), an insulating layer 21 is formed on the side surface of the battery stack 20. This results in a stacked battery 100.

Figure 5 is a schematic cross-sectional view illustrating a method for manufacturing a stacked battery in the present disclosure. As shown in Figure 5(a), a battery stack 20 having an extension portion 6 may be produced at the stage of stacking each layer. Next, as shown in Figure 5(b), the end faces of the positive electrode active material layer 1 (1a, 1b) and the negative electrode active material layer 2 (2a, 2b) are scraped. Note that in the manufacturing method shown in Figure 5, the step of scraping the end faces is not essential and can be omitted. Next, as shown in Figure 5(c), an insulating layer 21 is formed on the side of the battery stack 20. This results in a stacked battery 100.

This disclosure is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and anything that has substantially the same configuration as the technical ideas described in the claims of this disclosure and has similar effects is included within the technical scope of this disclosure.

REFERENCE SIGNS LIST 1 positive electrode active material layer 2 negative electrode active material layer 3 solid electrolyte layer 4 positive electrode current collector 5 negative electrode current collector 6 extension portion 10 power generation unit 20 battery stack 21 insulating layer 100 stacked battery

Claims (1)

a battery stack including a positive electrode active material layer, a negative electrode active material layer, a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer, a positive electrode current collector that collects current from the positive electrode active material layer, and a negative electrode current collector that collects current from the negative electrode active material layer;
an insulating layer covering a side surface of the battery stack, the battery stack being a lithium secondary battery ,
in a cross-sectional view of the battery stack in a stacking direction, the solid electrolyte layer, the positive electrode current collector, and the negative electrode current collector each have an extension portion located outside the positive electrode active material layer and the negative electrode active material layer,
When viewed in cross section, the extending portion of the solid electrolyte layer, the extending portion of the positive electrode current collector, and the extending portion of the negative electrode current collector have end surfaces positioned at the same position,
the insulating layer is in contact with an end face of the positive electrode active material layer, an end face of the negative electrode active material layer, an upper face of the extension portion, and a lower face of the extension portion;
a distance from a position of the end face of the positive electrode active material layer to a position of the end face of the extension portion, and a distance from a position of the end face of the negative electrode active material layer to a position of the end face of the extension portion are 3 mm or more and 10 mm or less .

Images