JP7613437B2 - Manufacturing method for all-solid-state batteries - Google Patents

Description

This disclosure relates to a method for manufacturing an all-solid-state battery.

As a high-voltage, high-capacity all-solid-state battery, a stacked type all-solid-state battery in which multiple unit cells are stacked is known. A unit cell generally consists of a negative electrode collector layer, a negative electrode active material layer, a solid electrolyte layer, a positive electrode active material layer, and a positive electrode collector layer stacked in this order.

In such stacked solid-state batteries, the current collector tabs of each stacked unit battery are bundled together for each positive and negative electrode tab, thereby reducing the space occupied by the current collector tabs and increasing the volumetric energy of the entire battery. However, when the current collector tabs of the positive electrode current collector layer are folded to bundle them together, there is a risk that the current collector tabs of the positive electrode current collector layer may come into electrical contact with the negative electrode current collector layer or the negative electrode active material layer, causing a short circuit.

To prevent such short circuits from occurring, a method for manufacturing a stacked solid-state battery is known in which a coating device is used to immerse desired portions of a unit battery in an insulating coating liquid to form an insulating portion (hereinafter also referred to as an "electrical insulating layer") (see, for example, Patent Document 1).

JP 2018-049696 A

However, with conventional manufacturing methods, the operation of the coating device may take time.

The present disclosure has been made in consideration of the above circumstances. The problem that one embodiment of the present disclosure aims to solve is to provide a method for manufacturing an all-solid-state battery that can efficiently and stably form an electrical insulation layer to prevent the occurrence of a short circuit between a current collector tab of one current collector layer and the other current collector layer or active material layer.

Means for solving the above problems include the following embodiments.
<1> Preparing an electrode assembly in which at least a first current collector layer, a first active material layer, a first solid electrolyte layer, and a second active material layer are laminated in this order;
and sandwiching at least a portion of at least one edge of a main surface of the electrode body between a pair of elastic rollers that rotate while in contact with each other, and forming an electrical insulating layer that covers at least the first current collector layer and the first active material layer on a side surface of the one edge in a region that is sandwiched between the pair of elastic rollers.
<2> The formation of the electrical insulating layer includes
applying a photocurable resin composition to the side surface so as to cover at least the first current collector layer and the first active material layer, thereby forming a photocurable coating film;
and forming the electrical insulating layer by irradiating the photocurable coating film with light.
<3> The method includes laminating a second current collector layer on the second active material layer after forming the electrical insulation layer,
The method for producing an all-solid-state battery according to <1> or <2>, wherein the second current collector layer has a current collector tab extending from the one edge portion to a side of the electrode body.
<4> The method for producing an all-solid-state battery according to <3>, wherein the electrical insulating layer is formed at least in an area of the side surface corresponding to a position of the current collecting tab.
<5> The electrode body is formed by stacking a third active material layer, a second solid electrolyte layer, a fourth active material layer, the first current collector layer, the first active material layer, the first solid electrolyte layer, and the second active material layer in this order,
The method for producing an all-solid-state battery according to any one of <1> to <4>, wherein the electrical insulating layer covers at least the fourth active material layer, the first current collector layer, and the first active material layer.

The present disclosure provides a method for manufacturing an all-solid-state battery that can efficiently and stably form an electrical insulation layer to prevent the occurrence of a short circuit between the current collector tab of one current collector layer and the current collector layer or active material layer of the other current collector layer.

FIG. 1 is a perspective view of an all-solid-state battery according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view taken along line C2-C2 in FIG. FIG. 3 is a top view for explaining the method for manufacturing an all-solid-state battery according to an embodiment of the present disclosure. FIG. 4 is a side view for explaining the method for manufacturing an all-solid-state battery according to an embodiment of the present disclosure. FIG. 5 is a side view for explaining the method for manufacturing an all-solid-state battery according to an embodiment of the present disclosure.

(1) The manufacturing method of the all-solid-state battery of the present disclosure (hereinafter also simply referred to as the "manufacturing method of the present disclosure") includes preparing an electrode body in which at least a first current collector layer, a first active material layer, a first solid electrolyte layer, and a second active material layer are laminated in this order (hereinafter also referred to as the "preparation step"); and sandwiching at least a portion (hereinafter also referred to as the "prescribed portion") of at least one edge of the main surface of the electrode body between a pair of elastic rollers rotating while in contact with each other, and forming an electrical insulating layer that covers at least the first current collector layer and the first active material layer on the side surface (hereinafter also referred to as the "formation surface") of the region of the one edge that is sandwiched between the pair of elastic rollers (hereinafter also referred to as the "sandwich region") (hereinafter also referred to as the "formation step").

The "second active material layer" refers to an active material layer having a different polarity (positive or negative) from that of the first active material layer. The "principal surface" refers to the surface having the largest area, and is usually perpendicular to the stacking direction of the electrode body (hereinafter also referred to as the "stacking direction"). The "edge portion" includes the area near the edge (peripheral end) of the electrode body in a plan view from the stacking direction of the electrode body (hereinafter also simply referred to as the "planar view"), and may or may not include the edge of the electrode body. The "elastic roller" has a core metal and an elastically deformable elastic layer laminated on the outer peripheral surface of the core metal. The hardness of the elastic layer is softer than that of the electrode body, for example, about Shore hardness A5.

Since the manufacturing method of the present disclosure has the above-mentioned configuration, it can efficiently and stably form an electrical insulation layer for preventing the occurrence of a short circuit between the current collecting tab of one current collector layer and the other current collector layer or active material layer.
This effect is believed to be due to, but not limited to, the following reasons.
In order to form an electrical insulating layer more efficiently than the conventional method (e.g., Patent Document 1), it is effective to form the electrical insulating layer while transporting the electrode body using a pair of transport rollers. The electrode body usually has undulations in the stacking direction (i.e., thickness direction). The position (hereinafter also referred to as the "forming position") of the device (e.g., the application nozzle) that forms the electrical insulating layer is usually fixed. Therefore, in order to stably form the electrical insulating layer, it is necessary to guide the forming surface to the forming position so that the position of the forming surface does not vary with respect to the forming position.
However, when the pair of conveying rollers is a pair of metal rollers, the area sandwiched between the pair of metal rollers of the electrode body may not be easily corrected to be flat. This is considered to be because the electrode body and the pair of metal rollers are likely to be in line contact due to the first and second factors. The first factor is that the pair of metal rollers are installed at a predetermined interval to prevent damage to the electrode body. The second factor is that the interval between the pair of metal rollers may change due to the vibration of the rotating metal rollers. In other words, the position of the surface to be formed is likely to vary with respect to the formation position. As a result, there is a risk that the electrical insulation layer cannot be stably formed on the electrode body.
On the other hand, in the present disclosure, at least a part of at least one edge of the main surface of the electrode body is sandwiched between a pair of elastic rollers that rotate while in contact with each other. As a result, the electrode body comes into surface contact with the pair of elastic rollers, and the area of the electrode body sandwiched between the pair of elastic rollers is easily corrected to be flat. Therefore, the position of the surface to be formed is less likely to vary relative to the formation position. As a result, it is presumed that the manufacturing method of the present disclosure can efficiently and stably form an electrical insulation layer.

The all-solid-state battery obtained by the manufacturing method of the present disclosure is a laminated type. The all-solid-state battery has at least one unit all-solid-state battery. The unit all-solid-state battery is formed by laminating a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in this order. A positive electrode current collector layer having a current collector tab may be laminated on the positive electrode active material layer, and a negative electrode current collector layer having a current collector tab may be laminated on the negative electrode active material layer. In the present disclosure, an electrical insulating layer is formed on the side of at least one edge of the main surface of the electrode body, thereby preventing the occurrence of a short circuit.

(1.1) Preparation Step In the preparation step, an electrode body is prepared. The first current collector layer, the first active material layer, the first solid electrolyte layer, and the second active material layer included in the electrode body will be described later.

The method for preparing the electrode body may be any known manufacturing method for the electrode body (e.g., a wet-on-dry manufacturing method, a wet-on-wet manufacturing method, a lamination press manufacturing method, etc.). For the method for preparing the electrode body, refer to Patent Document 1.

The first current collector layer may or may not have a first current collector tab. When the first current collector layer does not have a first current collector tab, the manufacturing method of the present disclosure may include a first bonding step after the forming step. In the first bonding step, the first current collector tab is bonded to the first current collector layer. The bonding method may be any known method, such as laser welding.

The electrode body may have a second current collector layer laminated on the second active material layer, or may not have a second current collector layer laminated thereon. When the electrode body has a second current collector layer, the second current collector layer may have a second current collector tab, or may not have a second current collector layer. When the second current collector layer does not have a second current collector tab, the manufacturing method of the present disclosure may have a second bonding step after the formation step. In the second bonding step, the second current collector tab is bonded to the second current collector layer. The bonding method is the same as the method exemplified as the bonding method for the first bonding step.

The electrode body may have a configuration in which a third active material layer, a second solid electrolyte layer, a fourth active material layer, a first current collector layer, a first active material layer, a first solid electrolyte layer, and a second active material layer are laminated in this order (hereinafter also referred to as a "double-sided configuration"). The polarity of the third active material layer is the same as the polarity of the second active material layer. The configuration of the third active material layer may be the same as or different from the configuration of the second active material layer. The polarity of the fourth active material layer is the same as the polarity of the first active material layer. The configuration of the fourth active material layer may be the same as or different from the configuration of the first active material layer. The configuration of the second solid electrolyte layer may be the same as or different from the configuration of the first solid electrolyte layer.

(1.2) Forming process In the forming process, a predetermined portion of the electrode body is sandwiched between a pair of elastic rollers, and an electrical insulating layer is formed on the side of the sandwich region of the electrode body. As a result, even if the electrode body has undulations in the stacking direction, the sandwich region of the electrode body is corrected to be flat. In other words, the formation surface is likely to be flat in the transport direction of the electrode body. As a result, the electrical insulating layer is stably formed on the desired formation surface.

The pair of elastic rollers need only sandwich a specific portion, and depending on the size of the elastic rollers, they may sandwich the entire main surface of the electrode body, or may sandwich an entire edge of the main surface of the electrode body. Examples of materials for the elastic layers of the pair of elastic rollers include polyurethane rubber.

The electrical insulation layer needs to cover at least the first current collector layer and the first active material layer, and may cover the first current collector layer, the first active material layer, the first solid electrolyte layer, and the second active material layer. When the electrode body has a double-sided structure, the electrical insulation layer needs to cover the fourth active material layer, the first current collector layer, and the first active material layer, and may cover the third active material layer, the second solid electrolyte layer, the fourth active material layer, the first current collector layer, the first active material layer, the first solid electrolyte layer, and the second active material layer. The electrical insulation layer needs to be formed on at least a portion of the side surface of one edge of the main surface of the electrode body, and may be formed on the entire side surface of one edge of the main surface of the electrode body.

The method for forming the electrical insulating layer is not particularly limited, and examples thereof include the first method, the second method, and the like.
The first method includes applying a photocurable resin composition that covers at least the first current collector layer and the first active material layer to the side surface to form a photocurable coating film (hereinafter also referred to as the "application step"); and irradiating the photocurable coating film with light to form the electrical insulation layer (hereinafter also referred to as the "light irradiation step").
The second method includes applying a known electrically insulating composition that covers at least the first current collector layer and the first active material layer to form an electrically insulating coating, and drying the electrically insulating coating to form the insulating layer.

Among them, the first method is preferred as the method for forming the electrical insulation layer. This allows the electrical insulation layer to be formed more stably at the desired position. The photocurable resin composition contains, for example, a compound having a plurality of photopolymerizable carbon-carbon double bonds (e.g., (meth)acrylic resin composition, epoxy resin composition, fluorine resin composition, olefin resin composition, etc.), and may contain a photopolymerization initiator (e.g., benzophenone-based, anthraquinone-based, benzoyl-based, sulfonium salt, diazonium salt, onium salt, etc.) as necessary. The method for applying the photocurable resin composition is not particularly limited, and examples include a method using a dispenser, a method using an inkjet device, and a spray application method. The light for light irradiation may be active energy rays (e.g., visible light, ultraviolet light, X-rays, electron beams, etc.), and is appropriately selected depending on the type of photocurable resin composition, etc. Light sources include metal halide lamps, high-pressure mercury lamps, xenon lamps, halogen lamps, pulsed xenon lamps, black lights (wavelength: approximately 365 nm), ultraviolet light-emitting diodes (hereinafter also referred to as "UV-LEDs") (wavelength: approximately 375 nm), light-emitting diode lamps (wavelength: approximately 405 nm), etc.

(1.3) Attachment step The manufacturing method of the present disclosure includes laminating a second current collector layer on the second active material layer after forming the electrical insulation layer (hereinafter also referred to as the "attachment step"), and the second current collector layer preferably has a current collector tab extending from the one edge portion to the side of the electrode body. This makes it possible to more efficiently form the electrical insulation layer on the electrode body.
The method for laminating the second current collector layer is not particularly limited, and examples thereof include a method using a known adhesive (for example, a hot melt adhesive).

When the manufacturing method of the present disclosure includes an attachment step, it is preferable that the electrical insulation layer is formed at least in the region of the side surface that corresponds to the position of the current collecting tab. The "position of the current collecting tab" refers to the region at the base of the part of the current collecting tab that extends to the side of the electrode body in a plan view. This makes it possible to efficiently prevent the occurrence of short circuits in the obtained all-solid-state battery. From the viewpoint of more reliably preventing the occurrence of short circuits, it is preferable that the electrical insulation layer is formed on the entire side surface of one edge portion of the main surface of the electrode body.

(1.4) Lamination process The manufacturing method of the present disclosure may include laminating a plurality of electrode bodies in the lamination direction of the electrode bodies (hereinafter, also referred to as the "lamination process"). This results in an all-solid-state battery having a plurality of unit all-solid-state batteries. The method for laminating the electrode bodies may be any known method (for example, a method of applying pressure to the electrode bodies while heating them, etc.).

(1.5) Layers of the electrode body When the first current collector layer is a negative current collector layer, the first active material layer is a negative active material layer, the second active material layer is a positive active material layer, and the second current collector layer is a positive current collector layer. When the electrode body has a double-sided structure and the first current collector layer is a negative current collector layer, the third active material layer is a positive active material layer, and the fourth active material layer is a negative active material layer.
When the first current collector layer is a positive electrode current collector layer, the first active material layer is a positive electrode active material layer, the second active material layer is a negative electrode active material layer, and the second current collector layer is a negative electrode current collector layer. When the electrode body has a double-sided structure and the first current collector layer is a positive electrode current collector layer, the third active material layer is a negative electrode active material layer, and the fourth active material layer is a positive electrode active material layer.

(1.5.1) Current collector layer Examples of materials constituting the positive electrode current collector layer include stainless steel (SUS), Ni, Cr, Au, Pt, Al, Fe, Ti, Zn, etc. Examples of materials constituting the negative electrode current collector layer include SUS, Cu, Ni, Fe, Ti, Co, Zn, etc.

(1.5.2) Positive Electrode Active Material Layer The positive electrode active material layer includes a positive electrode active material, and may further include a solid electrolyte, a binder, and a conductive material. The positive electrode active material may be a known positive electrode active material (e.g., lithium cobalt oxide, etc.). The solid electrolyte may be a known solid electrolyte (e.g., a sulfide-based solid electrolyte, etc.). The binder may be a known binder (e.g., polyvinylidene fluoride, etc.). The conductive material may be a known conductive material (e.g., carbon nanofiber, etc.).

(1.5.3) Negative electrode active material layer The negative electrode active material layer includes a negative electrode active material, and may further include a solid electrolyte, a binder, and a conductive material. The negative electrode active material may be a known negative electrode active material (e.g., graphite, etc.). The solid electrolyte and the binder may be appropriately selected from the materials described above as being usable in the positive electrode active material layer. The conductive material may be a known conductive material (e.g., acetylene black, etc.).

(1.5.4) Solid electrolyte layer The solid electrolyte layer includes a solid electrolyte and may further include a binder. As the solid electrolyte, the materials described above as usable for the positive electrode active material layer can be used. The binder may be any known binder (e.g., butadiene rubber, etc.).

(2) Embodiment Hereinafter, a method for manufacturing an all-solid-state battery according to an embodiment of the present disclosure will be described with reference to Fig. 1 to Fig. 5. In Fig. 3 to Fig. 5, the symbol "D1" indicates the conveying direction of the electrode body 11 sandwiched between a pair of elastic rollers 910. The symbol "D2" indicates the rotation direction of the first elastic roller 911. The symbol "D3" indicates the rotation direction of the second elastic roller 912.

The method for manufacturing an all-solid-state battery according to the embodiment includes a preparation step, a formation step, an attachment step, and a lamination step. The preparation step, formation step, attachment step, and lamination step are performed in this order. In this way, an all-solid-state battery 2 is obtained.

(2.1) All-solid-state battery As shown in Fig. 1, the all-solid-state battery 2 is formed by stacking a plurality of unit all-solid-state batteries 1. The unit all-solid-state battery 1 includes an electrode body 10 with an electrically insulating layer, and a positive electrode current collector layer 20 stacked on the electrode body 10 with an electrically insulating layer. The electrode body 10 with an electrically insulating layer has a negative electrode current collector tab 10T. The positive electrode current collector layer 20 has a positive electrode current collector tab 20T. The shape of the unit all-solid-state battery 1 is rectangular in a plan view.

The side of the positive electrode current collector tab 20T in the longitudinal direction of the unit all-solid-state battery 1 is defined as the X-axis positive direction, and the opposite side is defined as the X-axis negative direction. The side of the positive electrode current collector tab 20T in the lateral direction of the unit all-solid-state battery 1 is defined as the Y-axis positive direction, and the opposite side is defined as the Y-axis negative direction. One side of the thickness direction of the unit all-solid-state battery 1 is defined as the Z-axis positive direction, and the opposite side is defined as the Z-axis negative direction.

As shown in Fig. 2, the electrode body 10 with an electrical insulation layer has an electrode body 11 and an electrical insulation layer 12C. The electrical insulation layer 12C is formed on the entire surface of one side surface of the electrode body 11 (i.e., the side surface on the positive side of the X-axis). The thickness (length in the X-direction) of the electrical insulation layer 12C is, for example, 5 µm to 95 µm. The length (length in the Y-direction) of the electrical insulation layer 12C is, for example, 65.2 mm to 69.2 mm. The width (length in the Z-direction) of the electrical insulation layer 12C is, for example, 140 µm or less.
The electrode body 11 is formed by stacking a positive electrode active material layer 114, a solid electrolyte layer 113, a negative electrode active material layer 112, a negative electrode current collector layer 111, a negative electrode active material layer 112, a solid electrolyte layer 113, and a positive electrode active material layer 114 in this order along the Y direction.

(2.2) Preparation Step In the preparation step, the electrode body 11 is prepared. The method for preparing the electrode body 11 may be any known method for manufacturing an electrode body.

(2.3) Forming Step In the forming step, a predetermined portion of the electrode body 11 is sandwiched between a pair of elastic rollers 910, and an electrical insulating layer 12C is formed on the side surface S11 of the sandwich region of the electrode body 11.

The forming process is performed using an electrical insulation layer forming apparatus shown in Figures 3 to 5. The electrical insulation layer forming apparatus includes a pair of elastic rollers 910 (see Figure 5), a drive device (not shown) for the pair of elastic rollers, a dispenser 920, a storage container (not shown), a UV light source 930, and a transfer stage 940.
The pair of elastic rollers 910 includes a first elastic roller 911 and a second elastic roller 912. The first elastic roller 911 and the second elastic roller 912 are disposed in contact with each other so as to form a pressure contact region R, as shown in FIG.
The dispenser 920 is connected to a storage container. The storage container stores a photocurable resin composition and supplies the photocurable resin composition to the dispenser 920. As shown in Figs. 3 and 5, the dispenser 920 is disposed on one side of the pair of elastic rollers 910 and at approximately the center of the pressure contact region R in the Y-axis direction.
3, the UV light source 930 is disposed on one side of the pair of elastic rollers 910 and downstream of the dispenser 920 in the pressure contact region R in the transport direction D1.
The transport stage 940 is, for example, a belt conveyor. As shown in Fig. 4, the transport stage 940 is disposed on one side of the pair of elastic rollers 910. The transport stage 940 transports the portion of the electrode body 11 that is not sandwiched between the pair of elastic rollers 910 along the transport direction D1.

Specifically, a portion of one edge E11 (see FIG. 4) of the electrode body 11 is sandwiched between a pair of elastic rollers 910. The portion of the one edge E11 of the electrode body 11 sandwiched between the pair of elastic rollers 910 is corrected to be flat in the pressure contact region R. Next, the dispenser 920 ejects droplets D (see FIG. 3) of a photocurable resin composition to form a photocurable coating film 12U (see FIG. 3) on the side surface S11 of the portion of the one edge E11. The photocurable coating film 12U indicates an uncured product of the photocurable resin composition. Next, the UV light source 930 irradiates the photocurable coating film 12U with ultraviolet light L (see FIG. 3) to cure the photocurable coating film 12U to form an electrical insulating layer 12C. The electrical insulating layer 12C is a cured product of the photocurable resin composition. This results in an electrode body 10 with an electrical insulating layer.

(2.4) Attachment Step In the attachment step, the positive electrode current collector layer 20 is laminated on at least one of the two positive electrode active material layers 114 included in the electrode body with an electrical insulation layer 10. The method for laminating the positive electrode current collector layer 20 may be a method using a known adhesive.

(2.5) Stacking Step In the stacking step, a plurality of unit all-solid-state batteries 1 are stacked in the stacking direction (i.e., Z direction) of the electrode body 11. This results in an all-solid-state battery 2. The method for stacking the unit all-solid-state batteries 1 may be a known method.

(2.6) Effects The method for manufacturing an all-solid-state battery according to the embodiment includes preparing an electrode body 11, sandwiching at least a part of one edge E11 of the main surface of the electrode body 11 between a pair of elastic rollers 910, and forming an electrical insulating layer 12C on the side surface S11 of the region of the one edge E11 sandwiched between the pair of elastic rollers 910. As a result, the electrode body 11 is in surface contact with the pair of elastic rollers 910, and the region of the electrode body 11 sandwiched between the pair of elastic rollers 910 is easily corrected to be flat. Therefore, the position of the formation surface E11 is unlikely to vary with respect to the position of the dispenser 920. As a result, the method for manufacturing an all-solid-state battery according to the embodiment can efficiently and stably form an electrical insulating layer 12C for preventing the occurrence of a short circuit between the positive electrode current collector tab 20T of the positive electrode current collector layer 20 and the negative electrode current collector layer 111 or the negative electrode active material layer 112.

Claims (5)

preparing an electrode assembly in which at least a first current collector layer, a first active material layer, a first solid electrolyte layer, and a second active material layer are laminated in this order;
and sandwiching at least a portion of at least one edge of a main surface of the electrode body between a pair of elastic rollers that rotate while in contact with each other, and forming an electrical insulating layer that covers at least the first current collector layer and the first active material layer on a side surface of the one edge in a region that is sandwiched between the pair of elastic rollers. Forming the electrical insulation layer includes:
applying a photocurable resin composition to the side surface so as to cover at least the first current collector layer and the first active material layer, thereby forming a photocurable coating film;
and forming the electrical insulating layer by irradiating the photocurable coating film with light. laminating a second current collector layer on the second active material layer after forming the electrical insulation layer;
3. The method for producing an all-solid-state battery according to claim 1, wherein the second current collector layer has a current collector tab extending from the one edge portion to a side of the electrode body. The method for manufacturing an all-solid-state battery according to claim 3, wherein the electrical insulation layer is formed at least in an area of the side surface that corresponds to the position of the current collecting tab. the electrode body is formed by laminating a third active material layer, a second solid electrolyte layer, a fourth active material layer, the first current collector layer, the first active material layer, the first solid electrolyte layer, and the second active material layer in this order,
The method for producing an all-solid-state battery according to claim 1 , wherein the electrical insulating layer covers at least the fourth active material layer, the first current collector layer, and the first active material layer.