JP7650415B2 - Manufacturing method of stacked battery - Google Patents

Description

This disclosure relates to a method for manufacturing a stacked battery.

From the standpoint of production efficiency and the like, stacked batteries are often produced by first fabricating a large-sized stacked battery and then cutting it to the desired size.
When attempting to cut a stacked battery as is with a cutting blade, the conductor contained in the cutting blade may fly off as chips and adhere to the cut surface of the stacked battery. When chips of the conductor adhere to the cut surface of the stacked battery, the chips act as connections that can cause current to leak and short circuits.

Patent Document 1 proposes a method for cutting stacked batteries using a cutting blade made of a ceramic material that is less likely to produce cutting chips.
Patent Documents 2 and 4 propose a method of cutting stacked batteries using a cutting blade whose cutting edge is coated with a material such as diamond-like carbon.
Patent Document 3 proposes a method of cutting a stacked battery from above and below using a pair of cutting blades known as gang blades.

JP 2003-308834 A JP 2010-238490 A International Publication No. 2021/193738 JP 2014-42951 A

As described above, in conventional manufacturing methods for stacked batteries, the type of cutting blade has been adjusted to reduce the amount of chips scattered from the cutting blade, and there is room for improvement in terms of manufacturing costs, etc. In view of the above situation, the objective of the present disclosure is to provide a manufacturing method for stacked batteries that suppresses short circuits caused by the adhesion of chips that occur when cutting stacked batteries.

Means for solving the above problems include the following means.
<1> A battery preparation step of preparing a stacked battery;
a polishing layer preparation step of providing a polishing layer on at least one end surface in the stacking direction of the stacked battery;
a cutting step of cutting the stacked battery having the abrasive layer thereon in a stacking direction with a cutting blade;
A method for manufacturing a stacked battery, comprising:
<2> The method for producing a stacked battery according to <1>, wherein the polishing layer contains at least one material selected from the group consisting of alumina, zirconia, silicon nitride, and magnesium oxide, and has a volume resistivity of 1×10 ¹² (Ω·m) or more.
<3> The method for manufacturing a stacked battery according to <1> or <2>, wherein the polishing layer preparation step is a step of providing a polishing layer on both end surfaces in a stacking direction of the stacked battery.
<4> The method for producing a stacked battery according to any one of <1> to <3>, wherein the cutting blade is a round blade having an outer circumferential edge that is a saw blade.
<5> The method for producing a stacked battery according to any one of <1> to <4>, wherein the stacked battery is an all-solid-state battery.

The present disclosure provides a method for manufacturing a stacked battery that prevents short circuits caused by the adhesion of cutting chips that occur when cutting a stacked battery.

4 is a schematic cross-sectional view of a stacked battery in a cutting step according to the present disclosure taken along a stacking direction thereof; FIG. 3A is a schematic cross-sectional view in the stacking direction of a stacked battery during an abrasive layer preparation step in Example 1, and FIG. 3B is a schematic cross-sectional view in the stacking direction of a stacked battery during a cutting step in Example 1. 1A is a schematic cross-sectional view in the stacking direction of a stacked battery during an abrasive layer preparation step in Example 2, and FIG. 1B is a schematic cross-sectional view in the stacking direction of a stacked battery during a cutting step in Example 2.

Hereinafter, an embodiment that is an example of the present disclosure will be described. These descriptions and examples are merely illustrative of the embodiment, and are not intended to limit the scope of the invention.
Each component may contain multiple types of the corresponding substance.

<Laminated Battery Manufacturing Method>
The manufacturing method of a stacked battery according to the present disclosure includes a battery preparation step of preparing a stacked battery, an abrasive layer preparation step of providing an abrasive layer on at least one end surface in the stacking direction of the stacked battery, and a cutting step of cutting the stacked battery with the abrasive layer provided thereon in the stacking direction with a cutting blade.

In the manufacturing method of a stacked battery according to the present disclosure, a stacked battery provided with an abrasive layer is cut in the stacking direction with a cutting blade. Therefore, chips generated when cutting the stacked battery are adhered to the abrasive layer and removed from the cutting blade, or the cutting blade is polished with the abrasive layer, thereby reducing chips adhering to the cutting blade. As a result, it is believed that short circuits caused by chips generated when cutting the stacked battery adhering to the cut surface inside the battery are suppressed.

Each step of the manufacturing method for the stacked battery according to the present disclosure will be described in detail below.

[Battery preparation process]
In the battery preparation step, a stacked battery is prepared.
The laminated battery may be, for example, a battery cell in which a positive electrode, a solid electrolyte layer, and a negative electrode are laminated in this order. In order to cut a plurality of battery cells together, a laminated battery may be prepared in which a plurality of battery cells are stacked. The laminated battery may also be a stack in which a plurality of battery cells are electrically joined.
The type of stacked battery is not particularly limited, and any known stacked battery such as a lithium secondary battery, a sodium ion secondary battery, or an all-solid-state battery can be used.

In particular, when the stacked battery is an all-solid-state battery, since all the materials are solid, cutting tends to generate chips, which also tends to cause short circuits due to the adhesion of chips to the inner cross section of the battery. However, in the manufacturing method of the stacked battery disclosed herein, even in the case of an all-solid-state battery having the above configuration, the cutting blade passes through the polishing layer to cut the stacked battery, so that adhesion of chips to the inner cross section of the battery is kept to a minimum, and short circuits due to the adhesion of chips can be suppressed.

[Polishing layer preparation process]
In the abrasive layer preparation step, an abrasive layer is provided on at least one end surface in the stacking direction of the stacked battery. In the abrasive layer preparation step, cutting chips adhering to the cutting blade can be removed.

The polishing layer preparation step is preferably a step of providing a polishing layer on both end surfaces in the stacking direction of the stacked battery. When the polishing layers are provided on both end surfaces, the effect of removing chips attached to the cutting blade is enhanced, and short circuits caused by the adhesion of chips during cutting of the stacked battery are further suppressed.
When providing the abrasive layer, a fixing jig may be further provided to fix the stacked battery. The order of the fixing jig and the abrasive layer is not particularly limited.

The material of the polishing layer is not particularly limited as long as it can polish and remove the chips attached to the cutting blade, but for example, a material with high electrical insulation is preferable. The polishing layer preferably has a volume resistivity of 1×10 ¹⁰ (Ω·m) or more, more preferably 1×10 ¹¹ (Ω·m) or more, even more preferably 1×10 ¹² (Ω·m) or less, and particularly preferably 1×10 ¹² (Ω·m) or more and 1×10 ¹⁷ (Ω·m) or less. When the volume resistivity of the polishing layer is within the above range, short circuits caused by adhesion of chips generated when cutting the stacked battery are further suppressed. The volume resistivity of the polishing layer is in accordance with the measurement method described in JIS C2139-3.

The polishing layer preferably contains at least one material selected from the group consisting of alumina, zirconia, silicon nitride, and magnesium oxide, and more preferably contains at least one material selected from the group consisting of zirconia, silicon nitride, and magnesium oxide. When the polishing layer contains at least one material selected from the above group, a material with higher insulating properties adheres to the stacked battery, ensuring insulation, thereby further suppressing short circuits caused by the adhesion of cutting chips generated when cutting the stacked battery.

In one embodiment, from the viewpoint of further suppressing short circuits caused by the adhesion of cutting chips generated when cutting the stacked battery, the polishing layer preferably contains at least one material selected from the group consisting of alumina, zirconia, silicon nitride and magnesium oxide and has a volume resistivity of 1×10 ¹² (Ω·m) or more, and more preferably contains alumina and has a volume resistivity of 1×10 ¹² (Ω·m) or more.

The thickness of the polishing layer is not particularly limited, but from the viewpoint of further suppressing short circuits caused by the adhesion of cutting chips generated when cutting a stacked battery, it is preferable that the thickness is 0.5 mm or more, and more preferably 1 mm to 50 mm.

[Cutting process]
In the cutting step, the stacked battery having the abrasive layer is cut in the stacking direction with a cutting blade, which reduces adhesion of cutting chips to the cut surface that occurs when the stacked battery is cut.

The type of cutting blade is not particularly limited as long as it can cut the stacked battery, and any known cutting blade can be used, including round blades such as slitter, gang blade, and circular saw blade, and flat blades such as cutter blade, push cutter blade, razor blade, and rotary cutter. The cutting blade may be of one type alone or in combination of two or more types.
The material of the cutting blade is not particularly limited as long as it can cut the laminated battery, and known materials such as alloys, ceramics, diamond-like carbon, and combinations of these can be used. The material of the cutting blade may be one type alone or two or more types in combination.
For example, from the viewpoint of further suppressing short circuits caused by adhesion of cutting chips generated when cutting the stacked battery, the cutting blade may have a blade portion (i.e., the cutting portion) coated with a material that is unlikely to generate cutting chips, such as diamond-like carbon. For example, from the viewpoint of cutting performance, the cutting blade may have a blade portion (i.e., the cutting portion) shaped like a saw blade.

The cutting blade may be a round blade with a saw blade at its outer periphery. In a conventional cutting process for stacked batteries, when a round blade with a saw blade at its outer periphery (i.e., the cutting blade portion) is used, cutting chips are likely to be generated during the cutting process, and short circuits due to the adhesion of the chips are also likely to occur. However, in the manufacturing method for stacked batteries disclosed herein, even when a round blade with a saw blade at its outer periphery is used, the cutting blade passes through the polishing layer to cut the stacked battery, so short circuits due to the adhesion of the chips can be suppressed.

An example of a cutting step in the manufacturing method of a stacked battery according to the present disclosure will be described with reference to the drawings.
FIG. 1 is an example of a schematic cross-sectional view of a stacked battery in a stacking direction in a cutting step of the present disclosure.
In FIG. 1, an abrasive layer 11 is provided on a surface at one end in the stacking direction of a stacked battery 10 (more specifically, on the surface opposite the side where a cutting blade enters).
In FIG. 1, the stacked battery 10 is sandwiched between a fixing jig 12A and a fixing jig 12B.
1, for convenience, only a portion of the cutting blade 14 is shown, but the cutting blade 14 is a round blade with a saw blade at its outer circumferential edge. The cutting blade 14 is disposed opposite to the surface of the stacked battery 10 in the stacking direction. The cutting blade 14 may be connected to a pressing member.

In the cutting process in the configuration shown in FIG. 1, the cutting blade 14 is rotated in the direction of the arrow F while being pressed in the stacking direction to cut the stacked battery 10.
Although not shown, the fixing jig 12A has an insertion opening through which the cutting blade 14 is inserted into the region where the cutting blade will cut.
Although not shown, the abrasive layer 11 may or may not have an insertion opening for inserting the cutting blade 14 into the region to be cut by the cutting blade 14. If the abrasive layer 11 does not have an insertion opening in the region to be cut by the cutting blade 14, the cutting blade 14 cuts the stacked battery 10 together with the abrasive layer 11 in the stacking direction.

The positional relationship between the fixing jig 12A or the fixing jig 12B and the polishing layer 11 is not limited to any particular one, and the fixing jig 12A or the fixing jig 12B may be arranged to contact the stacked battery 10 in the order of the polishing layer 11, or the fixing jig 12A or the fixing jig 12B may be arranged to contact the stacked battery 10 in the order of the polishing layer 11, and the fixing jig 12A or the fixing jig 12B.
The stacked battery may be cut, for example, by cutting the polishing layer together with the stacked battery as shown in FIG. 2, or by providing an insertion opening in the polishing layer in advance for inserting a cutting blade and inserting the cutting blade into the insertion opening as shown in FIG. 3.

[Other steps]
The method for producing a stacked battery according to the present disclosure may include other steps in addition to the battery preparation step, the abrasive layer preparation step, and the cutting step.

The following examples are provided, but the present disclosure is not limited to these examples.

Example 1
In Example 1, a polishing layer having no voids in the cutting area of the laminated battery was used, and the laminated battery was cut together with the polishing layer to obtain the laminated battery of Example 1. Details are given below.

Battery Preparation Step A stacked battery described in paragraphs 0013 to 0019 of JP 2021-140948 A was prepared. The stacked battery is an all-solid-state battery in which a positive electrode, a positive electrode active material layer, a solid electrolyte, a negative electrode active material layer, and a negative electrode are stacked in this order.

Polishing Layer Preparation Step FIG. 2A is a schematic cross-sectional view in the stacking direction of the stacked battery during the polishing layer preparation step in Example 1, and FIG. 2B is a schematic cross-sectional view in the stacking direction of the stacked battery during the cutting step.
2A, from the side where the cutting blade 14 cuts in during the cutting process, the polishing layer 21A, the fixing jigs 22A and 22B, the stacked battery 20, the polishing layer 21B, and the fixing jig 22C were stacked in this order to prepare a stacked battery provided with a polishing layer. An insertion port (not shown) for the cutting blade 14 to enter was provided between the fixing jigs 22A and 22B, and alumina (purity 99.5%) with a thickness of 3 mm and a volume resistivity of 1×10 ¹⁵ (Ω·m) was used as the polishing layers 21A and 21B.

Cutting Step A round blade made of cemented carbide with a saw blade at the outer periphery was used for the cutting etc. 14 (also called a "metal saw"). The cutting blade 14 was pressed while rotating, and the stacked battery was cut together with the polishing layers 21A and 21B, as shown in FIG. 2(B). After cutting, the rotation of the cutting blade 14 was stopped, and the cutting blade 14 was slowly lifted up. Then, the fixing jigs 22A, 22B, and 22C and the cut polishing layers 21A and 21B were removed, and the stacked battery of Example 1 was obtained.

Example 2
In Example 2, a stacked battery of Example 2 was obtained in the same manner as in Example 1, except that a polishing layer having an insertion opening for inserting a cutting blade into the cutting area of the stacked battery was used instead of the polishing layer of Example 1. Details are shown below.

Battery Preparation Step A stacked battery was prepared similarly to that in Example 1. The stacked battery was an all-solid-state lithium ion battery in which a positive electrode, a positive electrode active material layer, a solid electrolyte, a negative electrode active material layer, and a negative electrode were stacked in this order.

FIG. 3A is a schematic cross-sectional view in the stacking direction of a stacked battery during an abrasive layer preparation step in Example 2, and FIG. 3B is a schematic cross-sectional view in the stacking direction of a stacked battery during a cutting step in Example 2.
3A, a stacked battery having a polishing layer was prepared by stacking polishing layers 31A and 31B, fixing jigs 32A and 32B, stacked battery 30, polishing layers 31C and 31D, and fixing jig 32C in this order from the side where cutting blade 14 cuts in. An insertion port for inserting cutting blade 14 was provided between polishing layers 31A and 31B, and alumina (purity 99.5%) having a thickness of 3 mm and a volume resistivity of 1×10 ¹⁵ (Ω·m) was used as polishing layers 31A, 31B, 31C, and 31D.

Cutting Step A round blade (also called a "metal saw") made of cemented carbide with a saw blade at the outer periphery was used for the cutting etc. 14. The cutting blade 14 was pressed while rotating, and cut the stacked battery so as to pass between the polishing layers 31A and 31B and between the polishing layers 31C and 31D as shown in FIG. 3B. After cutting, the rotation of the cutting blade 14 was stopped, and the cutting blade 14 was slowly lifted up. Then, the fixing jigs 22A, 22B, and 22C, and the polishing layers 31A, 31B, 31C, and 31D were removed, and the stacked battery of Example 2 was obtained.

<Short circuit evaluation>
The stacked battery of each example was charged by a constant current, constant voltage charging method (CCCV charging method) until the SOC (State of charge) reached 85% in a 25°C environment. Then, the cell voltage V1 when the battery was left to stand for 48 hours in a 25°C environment immediately after charging, and the cell voltage V2 when the battery was left to stand for 24 hours in a 25°C environment immediately after charging were measured in a 25°C environment. Since the difference between the obtained voltages (V1-V2) was less than 5.0 mV, it was determined that the stacked battery of the example did not have a short circuit due to the adhesion of cutting chips generated when cutting the stacked battery.

The stacked battery obtained by the manufacturing method of the embodiment was found to suppress short circuits caused by the adhesion of cutting chips generated when cutting the stacked battery.

REFERENCE SIGNS LIST 10 Stacked battery 11 Polishing layer 12A Fixing jig 12B Fixing jig 14 Cutting blade F Arrow direction 20 Stacked battery 21A, 21B Polishing layer 22A, 22B, 22C Fixing jig 30 Stacked battery 31A, 31B, 31C, 31D Polishing layer 32A, 32B, 32C Fixing jig

Claims (4)

a battery preparation step of preparing a stacked battery;
a polishing layer preparation step of providing a polishing layer on at least one end surface in the stacking direction of the stacked battery;
a cutting step of pressing a cutting blade in a stacking direction while rotating the cutting blade to cut the stacked battery provided with the abrasive layer in the stacking direction with the cutting blade;
Including ,
The method for producing a stacked battery , wherein the polishing layer contains at least one material selected from the group consisting of alumina, zirconia, silicon nitride, and magnesium oxide, and has a volume resistivity of 1×10 ¹² (Ω·m) or more . The method for manufacturing a stacked battery according to claim 1, wherein the polishing layer preparation step is a step of providing a polishing layer on both end surfaces in the stacking direction of the stacked battery. The method for manufacturing a stacked battery according to claim 1, wherein the cutting blade is a round blade whose outer periphery is a saw blade. The method for manufacturing a stacked battery according to claim 1, wherein the stacked battery is an all-solid-state battery.