Battery manufacturing method

Abstract

A method for manufacturing a battery having a current collector foil, an electrode layer, a separator, an electrode layer, and a current collector foil in this order, the method comprising: a step (A) in which the electrode layer is formed on the current collector foil using an electrode material; a step B in which an electrode layer is formed on the separator using an electrode material; and a step (C) in which a collector foil is placed on the electrode layer, each of the electrode materials containing an electrode active material, a conductive auxiliary agent, and an electrolyte solution, and the solid content concentration being 30-80 vol%.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a battery. Background Art

[0002] In recent years, the development of semi-solid batteries has been studied.

[0003] An electrode applicable to a semi-solid battery is manufactured, for example, using an electrode material containing at least a powder-based electrode active material and an electrolytic solution.

[0004] For example, Japanese Patent Application Laid-Open No. 2021-530829 discloses a method for manufacturing a battery, which includes the steps of: continuously dispensing a semi-solid electrode paste onto a current collector; separating the semi-solid electrode paste into individual portions; and cutting the current collector to form a completed electrode, and the method for manufacturing a battery further includes a step of forming a completed electrochemical cell by bringing the completed electrode into contact with a second completed electrode intervened by a separator. Further, FIG. 7 of Japanese Patent Application Laid-Open No. 2021-530829 describes a method of inclining the completed electrodes of the positive electrode and the negative electrode by 90 degrees respectively and continuously bonding the two via a separator. Summary of the Invention

[0005] Technical Problem to be Solved by the Invention

[0006] In the method described in Japanese Patent Application Laid-Open No. 2021-530829, since a battery can be continuously manufactured, the productivity is excellent.

[0007] On the other hand, when a large-area (large-sized) battery is to be obtained, the weights of the electrode layers of the positive electrode and the negative electrode also increase. In the case of a semi-solid battery, since the electrode layers of the positive electrode and the negative electrode both contain a large amount of powder as a solid component, when the electrode layers of the positive electrode and the negative electrode are inclined by 90 degrees (vertically) and continuously bonded via a separator as in the method described in Japanese Patent Application Laid-Open No. 2021-530829, collapse of the electrode layers sometimes occurs.

[0008] Therefore, the present invention has been completed in view of the above circumstances.

[0009] An object of an embodiment of the present invention is to provide a method for manufacturing a battery, which includes a step of forming an electrode layer using an electrode material containing an electrode active material, a conductive assistant, and an electrolytic solution, and can manufacture a large-area battery without causing collapse of the electrode layer.

[0010] Here, the "large-area battery" means a battery having an electrode layer area of 50000 cm 2 (for example, 100 mm × 500 mm) or more.

[0011] Means for Solving the Technical Problem

[0012] The present invention includes the following forms.

[0013] <1> A method for manufacturing a battery, the battery having a first current collector foil, a first electrode layer, a separator, a second electrode layer, and a second current collector foil in sequence, the method for manufacturing the battery including:

[0014] Step A of forming a first electrode layer on the first current collector foil using a first electrode material;

[0015] Step B of forming a second electrode layer on the separator using a second electrode material; and

[0016] Step C of placing the second current collector foil on the second electrode layer,

[0017] Both the first electrode material and the second electrode material include an electrode active material, a conductive additive, and an electrolytic solution, and the solid component concentration is 30% to 80% by volume.

[0018] <2> The method for manufacturing a battery according to <1>, wherein

[0019] Step A is a step of forming a positive electrode layer as the first electrode layer on the positive electrode current collector foil as the first current collector foil,

[0020] Step B is a step of forming a negative electrode layer as the second electrode layer on the separator placed on the positive electrode layer,

[0021] Step C is a step of placing the negative electrode current collector foil as the second current collector foil on the negative electrode layer.

[0022] <3> The method for manufacturing a battery according to <1>, wherein

[0023] Step A is a step of forming a negative electrode layer as the first electrode layer on the negative electrode current collector foil as the first current collector foil,

[0024] Step B is a step of forming a positive electrode layer as the second electrode layer on the separator placed on the negative electrode layer,

[0025] Step C is a step of placing the positive electrode current collector foil as the second current collector foil on the positive electrode layer.

[0026] <4> The method for manufacturing a battery according to <1>, wherein

[0027] Step A is a step of forming a positive electrode layer as the first electrode layer on the positive electrode current collector foil as the first current collector foil,

[0028] Step B is a step of forming a negative electrode layer as the second electrode layer on the separator,

[0029] Step C is a step of placing a current collector foil for the negative electrode, which is the second current collector foil, on the negative electrode layer.

[0030] The method for manufacturing the battery further includes a step D1 of placing a separator together with the negative electrode layer formed on the separator on the positive electrode layer.

[0031] <5> According to the method for manufacturing a battery according to <1>, wherein

[0032] Step A is a step of forming a negative electrode layer as the first electrode layer on a current collector foil for the negative electrode, which is the first current collector foil.

[0033] Step B is a step of forming a positive electrode layer as the second electrode layer on the separator.

[0034] Step C is a step of placing a current collector foil for the positive electrode, which is the second current collector foil, on the positive electrode layer.

[0035] The method for manufacturing the battery further includes a step D2 of placing a separator together with the positive electrode layer formed on the separator on the negative electrode layer.

[0036] <6> According to the method for manufacturing a battery according to any one of <1> to <5>, wherein

[0037] Step A is a step of intermittently or continuously supplying a first electrode material to the first current collector foil and restricting the thickness of the supplied first electrode material to form the first electrode layer.

[0038] When the mass of the first electrode material supplied to the first current collector foil is set to G D1 [g], and the mass of the formed first electrode layer is set to G L1 [g], it satisfies G L1 ≤G D1 ≤G L1 ×1.2.

[0039] <7> According to the method for manufacturing a battery according to any one of <1> to <6>, wherein

[0040] Step B is a step of intermittently or continuously supplying a second electrode material to the separator and restricting the thickness of the supplied second electrode material to form the second electrode layer.

[0041] When the mass of the second electrode material supplied to the separator is set to G D2 [g], and the mass of the formed second electrode layer is set to G L2 [g], it satisfies G L2 ≤G D2 ≤G L2 ×1.2.

[0042] Advantages of the Invention

[0043] According to an embodiment of the present invention, a method for manufacturing a battery can be provided, which includes a step of forming an electrode layer using an electrode material containing an electrode active material, a conductive assistant, and an electrolyte, and can manufacture a large-area battery without collapsing the electrode layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 FIG. is a schematic process diagram showing an example of the method for manufacturing a battery according to the present invention.

[0045] Figure 2 FIG. is a schematic diagram showing an example of the method for forming an electrode layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited by any of the following embodiments, and within the scope of the object of the present invention, modifications can be appropriately made and implemented. Components denoted by the same reference numerals in the respective drawings are the same components. Regarding the components and reference numerals that are repeated in the respective drawings, the description may sometimes be omitted. The ratio of the dimensions in the drawings does not necessarily represent the ratio of the actual dimensions.

[0047] In the present invention, the numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. In the numerical ranges described stepwise in the present invention, the upper limit value or the lower limit value described in a certain numerical range can be replaced with the upper limit value or the lower limit value of other stepwise described numerical ranges. And, in the numerical ranges described in the present invention, the upper limit value or the lower limit value described in a certain numerical range can also be replaced with the value shown in the examples.

[0048] In the present invention, the term "step" includes not only independent steps, but also includes this term even in cases where it cannot be clearly distinguished from other steps as long as the intended purpose of the step can be achieved.

[0049] In the present invention, regarding the amount of each component in the composition, when there are multiple substances corresponding to each component in the composition, unless otherwise specified, it means the total amount of the multiple substances present in the composition.

[0050] In the present invention, the combination of two or more preferred forms or modes is a more preferred form or mode.

[0051] In the present invention, "solid component" means a component that is solid at 25°C and one atmosphere, and "liquid component" means a component that is liquid at 25°C and one atmosphere.

[0052] <Battery Manufacturing Method>

[0053] The manufacturing method of the battery according to the present invention is a manufacturing method of a battery having a first current collector foil, a first electrode layer, a separator, a second electrode layer, and a second current collector foil in this order, and includes: Step A of forming a first electrode layer on the first current collector foil using a first electrode material; Step B of forming a second electrode layer on the separator using a second electrode material; and Step C of placing the second current collector foil on the second electrode layer. Moreover, both the first electrode material and the second electrode material contain an electrode active material, a conductive assistant, and an electrolytic solution, and the solid component concentration is 30% by volume to 80% by volume.

[0054] In the manufacturing method of the battery according to the present invention, as preferred embodiments, the following First-1 Embodiment and First-2 Embodiment can be cited.

[0055] The First-1 Embodiment is as follows: Step A is a step of forming a positive electrode layer as the first electrode layer on the positive electrode current collector foil as the first current collector foil, Step B is a step of forming a negative electrode layer as the second electrode layer on the separator placed on the positive electrode layer, and Step C is a step of placing the negative electrode current collector foil as the second current collector foil on the negative electrode layer.

[0056] The First-2 Embodiment is as follows: Step A is a step of forming a negative electrode layer as the first electrode layer on the negative electrode current collector foil as the first current collector foil, Step B is a step of forming a positive electrode layer as the second electrode layer on the separator placed on the negative electrode layer, and Step C is a step of placing the positive electrode current collector foil as the second current collector foil on the positive electrode layer.

[0057] Moreover, in the manufacturing method of the battery according to the present invention, as preferred embodiments, the following Second-1 Embodiment and Second-2 Embodiment can be cited.

[0058] The Second-1 Embodiment is as follows: Step A is a step of forming a positive electrode layer as the first electrode layer on the positive electrode current collector foil as the first current collector foil, Step B is a step of forming a negative electrode layer as the second electrode layer on the separator, Step C is a step of placing the negative electrode current collector foil as the second current collector foil on the negative electrode layer, and further includes Step D1 of placing the separator and the negative electrode layer formed on the separator together on the positive electrode layer.

[0059] The Second-2 Embodiment is as follows: Step A is a step of forming a negative electrode layer as the first electrode layer on the negative electrode current collector foil as the first current collector foil, Step B is a step of forming a positive electrode layer as the second electrode layer on the separator, Step C is a step of placing the positive electrode current collector foil as the second current collector foil on the positive electrode layer, and further includes Step D2 of placing the separator and the positive electrode layer formed on the separator together on the negative electrode layer.

[0060] Preferably, both the first electrode layer formed in the above-mentioned step A and the second electrode layer formed in step B contain an electrode active material, a conductive additive, and an electrolytic solution, have a thickness of 50 μm to 500 μm, and a solid component concentration of 30 vol% to 80 vol%. That is, in the method for manufacturing a battery according to the present invention, it is preferable to form a first electrode layer having a thickness of 50 μm to 500 μm and a solid component concentration of 30 vol% to 80 vol% in step A, and to form a second electrode layer having a thickness of 50 μm to 500 μm and a solid component concentration of 30 vol% to 80 vol% in step B.

[0061] In addition, in this specification, when simply referred to as "current collector foil" without special designation, both the first current collector foil and the second current collector foil are described. Similarly, when simply referred to as "electrode layer" without special designation, both the first electrode layer and the second electrode layer are described. Similarly, when simply referred to as "electrode material", both the first electrode material and the second electrode material are described. Further, the "first electrode material and the second electrode material containing an electrode active material, a conductive additive, and an electrolytic solution, and having a solid component concentration of 30 vol% to 80 vol%" are simply collectively referred to as "electrode material".

[0062] Here, the thickness of the electrode layer is set to the arithmetic average of the thicknesses of three portions measured by cross-sectional observation. In cross-sectional observation, a known microscope (for example, a scanning electron microscope) can be used.

[0063] Moreover, the solid component concentration of the electrode layer is calculated based on the composition ratio of each component contained in the electrode layer and the specific gravity of these components.

[0064] As described above, when a large-area (large-sized) battery is to be obtained, the mass of the electrode layers of the positive electrode and the negative electrode also increases. Therefore, when the electrode layers of the positive electrode and the negative electrode are respectively tilted by 90 degrees (vertically) and continuously laminated via a separator as described in Patent Document 1, collapse of the electrode layer sometimes occurs.

[0065] Therefore, the present inventors have found a method including the following steps: step A of forming an electrode layer on a current collector foil using an electrode material, step B of forming an electrode layer on a separator using an electrode material, and step C of placing a current collector foil on the electrode layer. According to this method, a battery having a layer structure of a positive electrode current collector foil, a positive electrode layer, a separator, a negative electrode layer, and a negative electrode current collector foil in sequence can be manufactured without tilting either the positive electrode layer or the negative electrode layer. As a result, a large-area (large-sized) battery can be manufactured without collapse of the positive electrode layer and the negative electrode layer.

[0066] Reference Figure 1 An example of the method for manufacturing a battery according to the present invention will be described. Here, Figure 1(a) to Figure 1 (e) is a schematic process diagram showing an example of the manufacturing method of the battery according to the present invention.

[0067] As Figure 1 shown in (a), first, the first current collector foil 30 with the resin film 32 is adsorbed onto the adsorption mechanism 20 placed on the stage 10. At this time, the resin film 32 is brought into contact with the adsorption mechanism 20.

[0068] Then, as Figure 1 shown in (a), the first electrode layer 40 is formed on the first current collector foil 30 using the electrode layer forming device 100A (process A). At this time, the electrode layer forming device 100A intermittently or continuously supplies the electrode material onto the first current collector foil 30 and limits the thickness of the supplied electrode material to form the first electrode layer 40.

[0069] Next, as Figure 1 shown in (b), the separator 50 is placed on the obtained first electrode layer 40.

[0070] Next, as Figure 1 shown in (c), the second electrode layer 60 is formed on the separator 50 using the electrode layer forming device 100B (process B).

[0071] Then, as Figure 1 shown in (d), the second current collector foil 70 is placed on the obtained second electrode layer 60 (process C). In addition, the second current collector foil 70 has a resin film (not shown) on its outermost surface. That is, at this stage, a laminate composed of resin film / first current collector foil / first electrode layer / separator / second electrode layer / second current collector foil / resin film can be obtained.

[0072] Then, as Figure 1 shown in (e), the laminate is pressed from above the resin film using the pressing member 110, and the resin films at the outer peripheral portions of the first electrode layer and the second electrode layer are heat-sealed to each other using the heat sealer 120.

[0073] By going through such processes, a battery having a first current collector foil, a first electrode layer, a separator, a second electrode layer, and a second current collector foil in sequence can be obtained.

[0074] 〔Process A〕

[0075] In process A, the first electrode layer is formed on the first current collector foil using the first electrode material.

[0076] In this process, as in the first - 1 form and the second - 1 form described above, a positive electrode layer can be formed as the first electrode layer on the positive - electrode current - collecting foil as the first current - collecting foil, or as in the first - 2 form and the second - 2 form, a negative electrode layer can be formed as the first electrode layer on the negative - electrode current - collecting foil as the first current - collecting foil.

[0077] The method of forming the first electrode layer on the first current - collecting foil is not particularly limited, and a method capable of forming a first electrode layer with a desired thickness and a continuous layer on the first current - collecting foil can be applied.

[0078] As a method of forming the first electrode layer on the first current - collecting foil, Figure 1 the method using the electrode - layer forming device 100A shown in (a) will be described. The electrode - layer forming device 100A forms the first electrode layer 40 while intermittently or continuously supplying the first electrode material to the first current - collecting foil 30 and restricting the thickness of the supplied first electrode material. Therefore, the electrode - layer forming device 100A has an electrode - material supply unit for supplying the first electrode material to the first current - collecting foil and a restricting member.

[0079] Hereinafter, Figure 2 a more specific description of the method of forming the first electrode layer will be given. Here, Figure 2 is a schematic diagram showing an example of the method of forming the electrode layer.

[0080] As Figure 2 shown, the electrode - layer forming device 100A has five restricting members 102 arranged in the arrow Y direction. An opening is provided in each restricting member 102 facing the first current - collecting foil 30, and the first electrode material is supplied to the current - collecting foil 30 through the opening. At this time, the first electrode material with the supply amount adjusted is supplied to the first current - collecting foil 30 through the opening by using one main screw 104 and branch screws 106 provided for the five restricting members 102 respectively.

[0081] Moreover, the restricting member 102 is arranged such that its front end maintains a certain distance from the surface of the first current - collecting foil 30. Preferably, the restricting member 102 also maintains a certain distance in the state of contacting the first electrode material and in the state of being conveyed and moving in the arrow X direction. That is, preferably, the restricting member 102 applies pressure to maintain a certain distance from the surface of the first current - collecting foil 30 against the repulsive force (i.e., the force pushing the restricting member 102 away) from the contacted first electrode material.

[0082] If the first electrode material is supplied between the current collector foil 30 and the restricting member 102 and the restricting member 102 is transported and moved in the direction of arrow X, the electrode material will pass through the gap between the restricting member 102 and the surface of the first current collector foil 30. When the first electrode material passes through this gap, the thickness of the first electrode material is restricted by contact with the restricting member 102. Furthermore, the first electrode material is applied to the surface of the first current collector foil 30, and thus the first electrode layer 40 is formed of the first electrode material on the first current collector foil 30.

[0083] In addition, the contact portion of the restricting member 102 with the first electrode material is preferably vibrated. Since the contact portion of the restricting member 102 with the first electrode material vibrates, this vibration is transmitted to the first electrode material to apply a shearing force, and thus a decrease in the viscosity of the first electrode material and an increase in fluidity may occur. As a result, it is easy to form the first electrode layer as a continuous layer on the current collector foil 30 without applying a large pressure to the first electrode material, and the planar shape of the surface of the formed first electrode layer also becomes flat.

[0084] In this method of forming the first electrode layer, for example, it is preferable to use the main screw 104 and the branch screw 106 described above to adjust the supply amount of the first electrode material onto the first current collector foil 30 to form the first electrode layer 40 that matches the size of the first current collector foil 30.

[0085] Moreover, when forming the first electrode layer on the first current collector foil, the screen printing method can be applied.

[0086] For example, a screen is pre-arranged on the first current collector foil, and the first electrode material is supplied onto the first current collector foil from above it. Then, the screen is removed, and the first electrode material supplied onto the first current collector foil is leveled using the restricting member, whereby a first electrode layer with excellent thickness uniformity can be formed.

[0087] As described above, in the case where this step is a step of intermittently or continuously supplying the first electrode material onto the first current collector foil and restricting the thickness of the supplied first electrode material to form the first electrode layer, when the mass of the first electrode material supplied onto the first current collector foil is set to G D1 [g] and the mass of the formed first electrode layer is set to G L1 [g], it is preferably satisfied that G L1 ≤G D1 ≤G L1 ×1.2, and more preferably satisfied that G L1 ≤G D1 ≤G L1 ×1.1.

[0088] By satisfying G L1 ≤G D1 ≤G L1×1.2 can suppress excessive supply of the first electrode material onto the first current collector foil, and can form the first electrode layer corresponding to the size of the first current collector foil with high precision.

[0089] The first current collector foil, the first electrode material, the supply mechanism of the first electrode material onto the first current collector foil, the restricting member, etc. used in this process will be described later.

[0090] In the above manner, in this process, the first electrode layer is formed on the first current collector foil from the first electrode material containing the electrode active material, the conductive assistant, and the electrolytic solution.

[0091] 〔Process B〕

[0092] In Process B, the second electrode layer is formed on the separator using the second electrode material.

[0093] In this process, as in the above-described First-1 form, the negative electrode layer can be formed as the second electrode layer on the separator placed on the positive electrode layer as the first electrode layer formed in Process A, or as in the First-2 form, the positive electrode layer can be formed as the second electrode layer on the separator placed on the negative electrode layer as the first electrode layer formed in Process A. That is, in the cases of the First-1 form and the First-2 form, this process (Process B) is carried out after Process A.

[0094] Moreover, in this process, as in the above-described Second-1 form, the negative electrode layer can be formed as the second electrode layer on the separator in a state where it is not placed on the positive electrode layer, or as in the Second-2 form, the positive electrode layer can be formed as the second electrode layer on the separator in a state where it is not placed on the negative electrode layer. That is, in the cases of the Second-1 form and the Second-2 form, this process (Process B) is not limited to being carried out after Process A.

[0095] As a method for forming the second electrode layer on the separator, it is not particularly limited, and a method capable of forming a second electrode layer with a desired thickness and a continuous layer on the separator can be applied.

[0096] In particular, in the cases of the First-1 form and the First-2 form, since the first electrode layer exists under the separator, in this process, it is preferable that the pressure applied to the separator and the electrode material during the formation of the first electrode layer is small.

[0097] Moreover, in the cases of the Second-1 form and the Second-2 form, it is preferable to use another device (for example, another stage) different from the device used in Process A to form the second electrode layer on the separator.

[0098] As a method for forming the electrode layer on the separator, as Figure 1As shown in (c), similar to Process A, it is preferable to use the method of the electrode layer forming apparatus 100B.

[0099] As a method of forming an electrode layer on the separator using the electrode layer forming apparatus 100B, the same method as the method of forming an electrode layer on the current collector foil in Process A can be applied, and the preferred embodiments are also the same.

[0100] In addition, as a method of placing the separator on the first electrode layer as in the above-described First-1 Embodiment and First-2 Embodiment, for example, a sheet feeder can be used.

[0101] As described above, this process is a process of intermittently or continuously supplying the second electrode material onto the separator and restricting the thickness of the supplied second electrode material to form the second electrode layer. When the mass of the second electrode material supplied onto the separator is G D2 [g] and the mass of the formed second electrode layer is G L2 [g], it is preferable to satisfy G L2 ≤ G D2 ≤ G L2 × 1.2, and more preferably satisfy G L2 ≤ G D2 ≤ G L2 × 1.1.

[0102] By satisfying G L2 ≤ G D2 ≤ G L2 × 1.2, excessive supply of the electrode material onto the separator can be suppressed, and an electrode layer corresponding to the size of the separator can be formed with high precision.

[0103] The separator and the like used in this process will be described later.

[0104] [Process C]

[0105] In Process C, a second current collector foil is placed on the second electrode layer.

[0106] In this process, as in the above-described First-1 Embodiment and Second-1 Embodiment, a negative current collector foil for the negative electrode can be placed on the negative electrode layer as the second electrode layer as the second current collector foil, or as in the First-2 Embodiment and Second-2 Embodiment, a positive current collector foil for the positive electrode can be placed on the positive electrode layer as the second electrode layer as the second current collector foil.

[0107] In addition, in the Second-1 Embodiment, it is preferable to perform this process after performing the following Process D1. That is, in Process D1, it is preferable to place the separator together with the negative electrode layer formed on the separator in Process B on the positive electrode layer formed in Process A, and then place the negative current collector foil on the negative electrode layer.

[0108] Further, in the second - second form, it is preferable to perform this step after performing step D2 described later. That is, in step D2, it is preferable to place the separator together with the positive electrode layer formed on the separator in step B on the negative electrode layer formed in step A, and then place the positive current collector foil on the positive electrode layer.

[0109] 〔Steps D1 and D2〕

[0110] In the case of the second - first form, it is preferable to further include step D1 of placing the separator together with the negative electrode layer as the second electrode layer formed on the separator in step B on the positive electrode layer as the first electrode layer formed in step A.

[0111] In the case of the second - second form, it is preferable to further include step D2 of placing the separator together with the positive electrode layer as the second electrode layer formed on the separator in step B on the negative electrode layer as the first electrode layer formed in step A.

[0112] As a method of moving the separator together with the second electrode layer formed on the separator, for example, a method of gripping the end of the separator (i.e., the unformed part of the electrode layer) and lifting it for transportation, a method of inserting a transport fork under the separator and lifting it for transportation, etc. can be cited.

[0113] Moreover, steps D1 and D2 can also be carried out as follows: The first current collector foil formed with the first electrode layer obtained in step A is conveyed by a belt conveyor, and downstream of the belt conveyor, the separator formed with the second electrode layer that has been previously lifted is placed on the first electrode layer of the conveyed first current collector foil.

[0114] As a mechanism for moving the separator formed with the second electrode layer, there is no particular limitation, and a mechanism that can align on the first electrode layer without damaging the formed second electrode layer is preferable. As a specific mechanism, a mechanism that adsorbs the end of the separator, a mechanism that grips the end of the separator, a mechanism such as a transport fork that lifts the separator from below, etc. can be used.

[0115] In the manufacturing method of the battery according to the present invention, in order to improve productivity, the apparatuses for performing step A, step B, step C, and step D1 or D2 can be respectively arranged in the process sequence and connected by a conveying mechanism to continuously perform these steps.

[0116] For example, in the case of the 1-1 form and the 1-2 form, while transporting the first current collector foil using a conveyor or the like, a first electrode layer is formed on the first current collector foil, a separator is placed on the formed first electrode layer, a second electrode layer is formed on the separator placed on the first electrode layer, and a second current collector foil is placed on the formed second electrode layer, whereby an electrode can be manufactured with high productivity.

[0117] 〔Preferred form〕

[0118] In the method for manufacturing a battery according to the present invention, it is preferable to select the 1-1 form among the 1-1 form and the 1-2 form.

[0119] This is because the electrode material for obtaining a positive electrode layer having a desired solid component concentration has a tendency to be higher in viscosity and harder than the electrode material for obtaining a negative electrode layer having the same solid component concentration. An electrode material with high viscosity and hardness is difficult to form an electrode layer with excellent thickness uniformity. However, even when using an electrode material for obtaining a positive electrode layer with high viscosity and hardness, when forming the positive electrode layer as the first electrode layer, a large pressure can be applied to the electrode material without considering the influence on the underlying layer as in the case of forming the second electrode layer, and thus a first electrode layer (i.e., positive electrode layer) with excellent in-plane uniformity of thickness can be formed. As a result, the first electrode layer (i.e., positive electrode layer) obtained by applying a large pressure also has excellent shape retention and can suppress collapse.

[0120] In the case of the 1-1 form, after forming the positive electrode layer, a separator is placed on the formed positive electrode layer, and a negative electrode layer is formed on the separator. The separator can hold the electrolyte in its structure or allow the electrolyte to pass through. Therefore, for example, the liquid component (mainly electrolyte) concentration of the electrode material for forming the positive electrode layer can be increased by the holding amount or passing amount of the separator. As a result, the solid component concentration of the electrode material for forming the positive electrode layer can be reduced, and in step A, an effect of easily forming a positive electrode layer with excellent in-plane uniformity of thickness can also be obtained.

[0121] In addition, as described above, since the electrolyte can move through the separator, sometimes the electrolyte is homogenized (averaged) between the formed positive electrode layer and the negative electrode layer.

[0122] From such a viewpoint, it is preferable to select the 1-1 form among the 1-1 form and the 1-2 form.

[0123] In addition, the steps of increasing the holding amount and the excess amount of the separator by increasing the concentration of the liquid component (mainly the electrolyte) of the electrode material used to form the positive electrode layer can also be applied to the first and second forms. That is, in the first and second forms, the concentration of the liquid component (mainly the electrolyte) of the electrode material used to form the negative electrode layer in process A can be increased to increase the holding amount and the excess amount of the separator.

[0124] Moreover, in the method for manufacturing a battery according to the present invention, by selecting the second - 1 form and the second - 2 form, the thickness uniformity of the electrode layer can be improved.

[0125] This is because, in the case of the second - 1 form and the second - 2 form, there is no electrode layer under the separator for forming the electrode layer.

[0126] In the case of the first - 1 form and the first - 2 form, the separator is placed on the electrode layer, and the electrode layer is formed on this separator. Therefore, when forming the second electrode layer on the separator, the pressure applied to the electrode material may affect the thickness of the first electrode layer as the lower layer. On the other hand, in the case of the second - 1 form and the second - 2 form, when forming the second electrode layer on the separator, since there is no electrode layer under the separator, the pressure applied to the electrode material does not affect the thickness of the first electrode layer as the lower layer, and an electrode layer with excellent thickness uniformity can be obtained.

[0127] 〔Other processes〕

[0128] The method for manufacturing a battery according to the present invention may include other processes.

[0129] As other processes, for example, a process of pressing the second current collector foil toward the second electrode layer side after process C (hereinafter, also referred to as process E), a process of thermally welding resin films to each other when using a current collector foil with a resin film as the current collector foil (hereinafter, also referred to as process F), etc. can be cited.

[0130] (Process E)

[0131] In process E, after placing the second current collector foil on the second electrode layer in process C, the second current collector foil is pressed toward the second electrode layer side.

[0132] As the pressing mechanism used in this process, for example, a squeegee, a pressing roller, a press, etc. can be cited. In addition, vibration can be applied during pressing. That is, when pressing the second current collector foil toward the second electrode layer side using the pressing mechanism, the pressing mechanism can vibrate.

[0133] In this step, the pressure when pressing the second current collector foil toward the second electrode layer side is preferably 0.01 MPa to 100 MPa, more preferably 0.1 MPa to 50 MPa, and particularly preferably 0.2 MPa to 10 MPa.

[0134] In this step, it is preferable to perform the pressing by relatively moving the pressing mechanism with respect to the electrode layer.

[0135] Moreover, in this step, multiple pressing mechanisms can be used to perform pressing step by step.

[0136] In this step, it is also possible to press, for example, the second current collector foil and the second electrode layer heated at 30°C to 100°C.

[0137] (Step F)

[0138] In Step F, in the case of using a current collector foil with a resin film as the current collector foil, for the laminate composed of resin film / first current collector foil / first electrode layer / separator / second electrode layer / second current collector foil / resin film, the resin films at the outer peripheral portions of the first electrode layer and the second electrode layer are heat-sealed to each other.

[0139] Specifically, as shown in Figure 1 (e), a heat sealer 120 is used to heat, for example, the resin films at the outer peripheral portions of the first electrode layer and the second electrode layer to a temperature higher than the glass transition temperature (Tg) of the resin film to heat-seal the resin films to each other.

[0140] As a method for heat-sealing the resin films to each other, it is not limited to a heat sealer, and any mechanism that can heat a desired region of the resin film to a desired temperature (for example, a temperature higher than the glass transition temperature (Tg) of the resin film) can be used. As a mechanism for heat-sealing the resin films to each other, for example, in addition to a hot plate frame, an infrared (IR) heater, a carbon dioxide gas laser (CO 2 laser), etc., a mechanism that can perform heat-sealing while scanning can also be used.

[0141] Hereinafter, details of the current collector foil, electrode material, separator, etc. used in the method for manufacturing the battery according to the present invention will be described.

[0142] Moreover, details of the mechanism for forming the electrode layer will also be described.

[0143] [Current Collector Foil]

[0144] As the current collector foil, there is no particular limitation, and known current collector foils (positive current collector foil and negative current collector foil) can be used.

[0145] As the positive current collector foil, for example, foils of aluminum, aluminum alloy, stainless steel, nickel, and titanium (i.e., metal layers) can be cited. The positive current collector foil is preferably aluminum or aluminum alloy. The positive current collector foil can also be aluminum having a coating layer containing one or more of carbon, nickel, titanium, silver, gold, platinum, and vanadium on the surface.

[0146] As the negative current collector foil, for example, foils of aluminum, copper, copper alloy, stainless steel, nickel, and titanium (i.e., metal layers) can be cited. The negative current collector foil is preferably aluminum, copper, copper alloy, or stainless steel, and more preferably copper or copper alloy. The negative current collector foil can also be copper or stainless steel having a coating layer containing one or more of carbon, nickel, titanium, silver, and lithium on the surface.

[0147] As the current collector foil, aluminum foil (including aluminum foil having the above coating layer on the surface) and copper foil (including copper foil having the above coating layer on the surface) are preferred. Aluminum foil is usually used as the positive current collector foil. Copper foil is usually used as the negative current collector foil.

[0148] And, as already described, the current collector foil can be provided with a resin film.

[0149] As the resin film, polyethylene terephthalate (PET) film, polypropylene (PP) film, polyethylene (PE) film, cyclic olefin polymer (COP, COC) film, triacetyl cellulose (TAC) film, polyimide (PI) film, and polyamide (PA) film can be cited.

[0150] From the viewpoints of transportability and the like, the thickness of the current collector foil (also including the case of a laminate) is preferably 3 μm or more, more preferably 5 μm or more, and particularly preferably 10 μm or more.

[0151] From the viewpoints of flexibility and light weight, the thickness of the current collector foil is preferably 100 μm or less, more preferably 70 μm or less, and particularly preferably 50 μm or less.

[0152] The thickness of the current collector foil is set as the arithmetic average of the thicknesses at three places measured by cross-sectional observation. In cross-sectional observation, a known microscope (for example, a scanning electron microscope) can be used.

[0153] [Electrode Material]

[0154] The electrode material contains an electrode active material, a conductive additive, and an electrolytic solution, and the solid component concentration is 30 vol% to 80 vol%.

[0155] In addition to the above three components, the electrode material can also contain additives as needed.

[0156] (Electrode Active Material)

[0157] The electrode active material is a material capable of inserting and releasing ions of a metal element belonging to Group 1 or Group 2 of the periodic table. The electrode active material is included in the solid component.

[0158] As the electrode active material, for example, a positive electrode active material and a negative electrode active material can be cited.

[0159] - Positive electrode active material -

[0160] As the positive electrode active material, there is no limitation, and a known electrode active material used in the positive electrode can be used. As the positive electrode active material, a positive electrode active material capable of reversibly inserting and releasing lithium ions is preferred.

[0161] As the positive electrode active material, specifically, for example, transition metal oxides and elements capable of being complexed with lithium (for example, sulfur) can be cited. Among the above, the positive electrode active material is preferably a transition metal oxide.

[0162] The transition metal oxide is preferably a transition metal oxide containing at least one transition metal element selected from the group consisting of Co (cobalt), Ni (nickel), Fe (iron), Mn (manganese), Cu (copper), and V (vanadium) (hereinafter referred to as "element Ma").

[0163] When the transition metal oxide contains Li and element Ma, the molar ratio of Li to Ma (Li / Ma) is preferably 0.3 to 2.2.

[0164] In addition, the transition metal oxide may contain at least one transition metal element selected from the group consisting of Group 1 elements, Group 2 elements, Al (aluminum), Ga (gallium), In (indium), Ge (germanium), Sn (tin), Pb (lead), Sb (antimony), Bi (bismuth), Si (silicon), P (phosphorus), and B (boron) other than lithium (hereinafter referred to as "element Mb"). The content of element Mb is preferably 0 mol% to 30 mol% relative to the amount of substance of element Ma.

[0165] As the transition metal oxide, for example, a transition metal oxide having a layered rock salt structure, a transition metal oxide having a spinel structure, a lithium-containing transition metal phosphate compound, a lithium-containing transition metal halophosphate compound, and a lithium-containing transition metal silicate compound can be cited.

[0166] As the transition metal oxide having a layered rock salt structure, for example, LiCoO 2 (lithium cobaltate [LCO]), LiNi 2 O 2 (lithium nickelate), LiNi 0.85 Co 0.10 Al0.05 O 2 (lithium nickel cobalt aluminum oxide [NCA]), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 (lithium nickel manganese cobalt oxide [NMC]) and LiNi 0.5 Mn 0.5 O 2 (lithium manganese nickel oxide).

[0167] Examples of transition metal oxides having a spinel structure include LiCoMnO 4 , Li 2 FeMn 3 O 8 , Li 2 CuMn 3 O 8 , Li 2 CrMn 3 O 8 Li 2 NiMn 3 O 8 .

[0168] Examples of lithium-containing transition metal phosphate compounds include olivine-type iron phosphates (e.g., LiFePO 4 Li 3 Fe 2 (PO 4 ) 3 ), ferric pyrophosphate (e.g., LiFeP 2 O 7 ), cobalt phosphates (e.g., LiCoPO 4 ), monoclinic NASICON-type vanadium phosphate salts (e.g., Li 3 V 2 (PO 4 ) 3 (lithium vanadium phosphate)).

[0169] Examples of lithium-containing transition metal halophosphate compounds include fluoroferric phosphates (e.g., Li 2 FePO 4 F), manganese fluorophosphate salts (e.g., Li 2 MnPO 4 F) and cobalt fluorophosphate salts (e.g., Li 2 CoPO 4 F).

[0170] Examples of lithium-containing transition metal silicate compounds include Li 2 FeSiO 4 , Li 2MnSiO 4 and Li 2 CoSiO 4 .

[0171] The transition metal oxide is preferably a transition metal oxide having a layered rock salt structure, more preferably at least one compound selected from the group consisting of LiCoO 2 (lithium cobalt oxide [LCO]), LiNi 0.85 Co 0.10 Al 0.05 O 2 (lithium nickel cobalt aluminum oxide [NCA]) and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 (lithium nickel manganese cobalt oxide [NMC]).

[0172] The positive electrode active material can be a commercially available product or a synthetic product manufactured by a known method (for example, a calcination method). For example, the positive electrode active material obtained by the calcination method can be washed with water, an acidic aqueous solution, a basic aqueous solution, or an organic solvent.

[0173] In addition, the positive electrode active material may have a carbon coating on its surface.

[0174] The shape of the positive electrode active material is not limited, but from the viewpoint of operability, it is preferably in the form of particles.

[0175] The volume average particle diameter of the positive electrode active material is not limited, and can be set to 0.1 μm to 50 μm, for example. The volume average particle diameter of the positive electrode active material is preferably 0.3 μm to 40 μm, more preferably 0.5 μm to 30 μm.

[0176] By the volume average particle diameter of the positive electrode active material being 0.3 μm or more, it is possible to suppress the splashing of the positive electrode active material during operation. By the volume average particle diameter of the positive electrode active material being 40 μm or less, it is possible to easily adjust the thickness of the electrode layer and suppress the generation of voids during the molding process.

[0177] The volume average particle diameter of the positive electrode active material is measured by the following method.

[0178] A dispersion containing 0.1% by mass or less of the positive electrode active material is prepared by mixing the positive electrode active material with a solvent (e.g., pure water, ethanol, heptane, octane, toluene, or xylene). The dispersion irradiated with ultrasonic waves at 1 kHz for 10 minutes is used as the measurement sample. Using a laser diffraction / scattering particle size distribution measuring device (e.g., LA-960 manufactured by HORIBA, Ltd.), 50 data readings are taken under the condition of a temperature of 25°C, and the volume average particle diameter is obtained based on the volume frequency particle size distribution. A quartz cuvette is used as the measurement cuvette. The above measurement is performed using 5 samples, and the average of the measured values is taken as the volume average particle diameter of the positive electrode active material. For other detailed conditions, refer to "JIS Z 8828:2013" as needed.

[0179] As a method for adjusting the particle diameter of the positive electrode active material, for example, a method using a crusher, disintegrator, or classifier can be cited. And, as a method for adjusting the particle diameter of the positive electrode active material, a known milling method can be applied.

[0180] The positive electrode active material can be used alone or in combination of two or more.

[0181] And, even in the case of using one positive electrode active material, positive electrode active materials with different particle diameters can be used in combination.

[0182] The content rate of the positive electrode active material relative to the total volume of the electrode material is preferably 30% to 60% by volume, more preferably 35% to 55% by volume, and further preferably 40% to 50% by volume.

[0183] In the method for manufacturing the electrode layer according to the present invention, the usage amount of the positive electrode active material is determined so that the content rate in the electrode layer is within the above range.

[0184] - Negative electrode active material -

[0185] As the negative electrode active material, there is no limitation, and known electrode active materials used in the negative electrode can be used. The negative electrode active material is preferably a negative electrode active material capable of reversibly inserting and releasing lithium ions.

[0186] As the negative electrode active material, for example, carbonaceous materials, metal oxides (e.g., tin oxide), silicon oxide, metal composite oxides, lithium monomers, lithium alloys (e.g., lithium aluminum alloy), and metals capable of forming alloys with lithium (e.g., Sn, Si, and In) can be cited. Among the above, from the viewpoint of reliability, the negative electrode active material is preferably a carbonaceous material or a lithium composite oxide.

[0187] The carbonaceous material is a material substantially composed of carbon.

[0188] As the carbonaceous material, examples thereof may include petroleum pitch, carbon black (e.g., acetylene black), graphite (e.g., natural graphite and artificial graphite (e.g., vapor-grown graphite)), hard carbon, and carbonaceous materials obtained by calcining synthetic resins (e.g., polyacrylonitrile (PAN) and furfuryl alcohol resin).

[0189] As the carbonaceous material, examples thereof may further include carbon fibers (e.g., polyacrylonitrile-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, dehydrated PVA (polyvinyl alcohol)-based carbon fiber, lignin carbon fiber, glassy carbon fiber, and activated carbon fiber). As the graphite, examples thereof may further include mesophase microspheres, graphite whiskers, and plate-like graphite.

[0190] In the present invention, "plate-like" means a shape having two main planes facing in opposite directions.

[0191] As the metal composite oxide, a metal composite oxide capable of occluding and releasing lithium is preferred.

[0192] From the viewpoint of the charge-discharge characteristics at a high current density, the metal composite oxide capable of occluding and releasing lithium preferably contains at least one element selected from the group including titanium and lithium.

[0193] The metal oxide and the metal composite oxide are particularly preferably amorphous oxides.

[0194] The metal oxide and the metal composite oxide are also preferably chalcogenides. Chalcogenides are reaction products of metal elements and Group 16 elements in the periodic table.

[0195] Among the compound groups including amorphous oxides and chalcogenides, amorphous oxides and chalcogenides of semi-metal elements are preferred, and oxides and chalcogenides containing at least one element selected from the group including Group 13 to 15 elements, Al, Ga, Si, Sn, Ge, Pb, Sb, and Bi in the periodic table are more preferred.

[0196] It is also preferred that the negative electrode active material further contains titanium. From the viewpoint of excellent rapid charge-discharge characteristics due to small volume change during occlusion and release of lithium ions and improving the life of the lithium ion secondary battery by suppressing electrode deterioration, the negative electrode active material containing titanium is preferably Li 4 Ti 5 O 12 (lithium titanate [LTO]).

[0197] The negative electrode active material can be a commercially available product or a synthetic product manufactured by a known method (for example, a calcination method). For example, the negative electrode active material obtained by the calcination method can be washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.

[0198] The negative electrode active material can be obtained, for example, as CGB20 (Nippon Graphite Industries Co., Ltd.).

[0199] The composition of the negative electrode active material is determined by inductively coupled plasma (ICP) emission spectrometry.

[0200] The shape of the negative electrode active material is not limited, but from the viewpoints of easy handling and easy management of uniformity during mass production, etc., it is preferably in the form of particles.

[0201] The volume average particle diameter of the negative electrode active material is preferably 0.1 μm to 60 μm, more preferably 0.3 μm to 50 μm, and particularly preferably 0.5 μm to 40 μm.

[0202] The volume average particle diameter of the negative electrode active material is measured by a method based on the method for measuring the volume average particle diameter of the positive electrode active material described above.

[0203] As a method for adjusting the particle diameter of the negative electrode active material, for example, a method using a pulverizer or a classifier can be cited.

[0204] The negative electrode active material can be used alone or in combination of two or more.

[0205] Moreover, even when using one kind of negative electrode active material, negative electrode active materials with different particle diameters can be used in combination.

[0206] The content rate of the negative electrode active material relative to the total volume of the electrode material is preferably 30% by volume to 60% by volume, more preferably 35% by volume to 57% by volume, and further preferably 45% by volume to 55% by volume.

[0207] In the method for manufacturing the electrode layer according to the present invention, the usage amount of the negative electrode active material is determined so that the content rate in the electrode layer is within the above range.

[0208] The surfaces of the positive electrode active material and the negative electrode active material can be respectively coated with a surface coating agent. As the surface coating agent, for example, metal oxides containing Ti, Nb, Ta, W, Zr, Si, or Li can be cited. As the above metal oxides, for example, spinel titanate, tantalum-based oxides, niobium-based oxides, and lithium niobate-based compounds can be cited.

[0209] (Conductive additive)

[0210] From the viewpoint of improving the electron conductivity of the electrode active material, the electrode layer contains a conductive additive. As the conductive additive, there is no limitation, and known conductive additives can be used.

[0211] The conductive additive is included in the solid component.

[0212] As the conductive additive, for example, graphite (e.g., natural graphite and artificial graphite), carbon black (e.g., acetylene black, Ketjen black, and furnace black), amorphous carbon (e.g., needle coke), carbon fiber (e.g., vapor grown carbon fiber and carbon nanotube), other carbonaceous materials (e.g., graphene and fullerene), metal powder (e.g., copper powder and nickel powder), metal fiber (e.g., copper fiber and nickel fiber), and conductive polymer (e.g., polyaniline, polypyrrole, polythiophene, polyacetylene, and polyphenylene derivative) can be cited.

[0213] The conductive additive can be used alone or in combination of two or more.

[0214] The content rate of the conductive additive relative to the total volume of the electrode material is preferably 0.05 vol% to 5 vol%, more preferably 0.1 vol% to 4 vol%, and further preferably 0.5 vol% to 3 vol%.

[0215] In the manufacturing method of the electrode layer according to the present invention, the usage amount of the conductive additive is determined so that the content rate in the electrode layer is within the above range.

[0216] (Electrolyte solution)

[0217] As the electrolyte solution, there is no particular limitation, and known electrolyte solutions can be used. As the electrolyte solution, for example, an electrolyte solution containing an electrolyte and a solvent can be cited. As a specific electrolyte solution, for example, an electrolyte solution containing a lithium salt compound as the electrolyte and a carbonate compound as the solvent can be cited.

[0218] As the lithium salt compound, for example, lithium hexafluorophosphate can be cited. The electrolyte solution can contain a single lithium salt compound or two or more lithium salt compounds.

[0219] As the carbonate compound, for example, chain carbonate compounds such as ethyl methyl carbonate (also called EMC), dimethyl carbonate (also called DMC), and diethyl carbonate (DEC), and cyclic carbonate compounds such as ethylene carbonate (also called EC) and propylene carbonate (also called PC) can be cited. The electrolyte solution can contain a single carbonate compound, two or more carbonate compounds, or can also use one or more chain carbonate compounds and one or more cyclic carbonate compounds in combination.

[0220] As the electrolyte contained in the electrolyte solution, for example, a known inorganic solid electrolyte can also be used.

[0221] As a component of the electrolyte solution, for example, an ionic liquid can be used. The ionic liquid can be used as an electrolyte or as a solvent.

[0222] The content rate of the electrolyte solution relative to the total volume of the electrode material is preferably 70% by volume or less, can also be 50% by volume or less, and can further be 40% by volume or less. The lower limit of the content rate of the electrolyte solution relative to the total volume of the electrode material is not limited and can be 20% by volume or more, or can also be 30% by volume or more.

[0223] The content rate of the electrolyte solution relative to the total volume of the electrode material is, for example, preferably 30% by volume to 50% by volume.

[0224] (Solvent)

[0225] In the electrode layer, as a liquid component, a solvent other than the solvent contained as a component of the electrolyte solution (hereinafter, also simply referred to as "solvent") can be included.

[0226] Examples of the solvent include an alcohol compound solvent, an ether compound solvent, an amide compound solvent, an amino compound solvent, a ketone compound solvent, an aromatic compound solvent, an aliphatic compound solvent, and a nitrile compound solvent.

[0227] The boiling point of the solvent is preferably 50°C or higher, more preferably 70°C or higher under normal pressure (i.e., one atmospheric pressure). The upper limit of the boiling point of the solvent is preferably 250°C or lower, more preferably 220°C or lower under normal pressure (i.e., one atmospheric pressure).

[0228] The solvent can be used alone or in combination of two or more.

[0229] The content rate of the liquid component (i.e., the electrolyte solution and the solvent) relative to the total volume of the electrode material is preferably 70% by volume or less, can also be 50% by volume or less, and can further be 40% by volume or less. The lower limit of the content rate of the liquid component relative to the total volume of the electrode material is not limited and can be 20% by volume or more, or can also be 30% by volume or more.

[0230] The content rate of the liquid component relative to the total volume of the electrode material is preferably 30% by volume to 50% by volume.

[0231] In addition, the liquid component contained in the electrode layer, that is, the component that is liquid at 25°C in the electrode layer, is preferably liquid even at -10°C and preferably liquid even at -20°C. That is, the component that is liquid at 25°C in the electrode layer is preferably a component that does not solidify at -10°C and preferably a component that does not solidify even at -20°C.

[0232] (Other components)

[0233] In addition to the above components, the electrode layer may further contain a binder, a dispersant, other additives, etc. Further, from the viewpoint of improving the energy density, the electrode layer preferably has a low content rate of the binder (also referred to as a resin component), preferably 1% by mass or less, and particularly preferably does not contain (0% by mass).

[0234] As the binder, it refers to components known as rheology modifiers and dispersants other than the binder in a known electrode layer, and examples thereof may include fluororesins, hydrocarbon-based thermoplastic resins, acrylic resins, and urethane resins.

[0235] And, as the dispersant, any known dispersant capable of dispersing the object to be dispersed may be used.

[0236] Moreover, as other additives, known additives that can be added to the electrode can be used.

[0237] [Separator]

[0238] As the separator, a known separator applicable to a semi-solid battery can be used.

[0239] Specifically, as the separator, porous membranes containing resin materials such as polyethylene, polypropylene, polybutene, polyvinyl chloride, polyethylene terephthalate, polyethersulfone, polyamide, polyimide, polyimide amide, polyaramide, polycycloolefin, nylon, and polytetrafluoroethylene can be cited.

[0240] The thickness of the separator is not particularly limited and can be set to 0.5 μm to 40 μm.

[0241] [Restricting member]

[0242] As the restricting member, a scraper and a roller can be cited as preferred examples.

[0243] As described above, by using a molding member that can vibrate or oscillate when in contact with the electrode material, the scraper and the roller as the molding members can vibrate the electrode material.

[0244] (Scraper)

[0245] The scraper is a member having a plate-like shape, and the shape, size, material, etc. of the contact portion in contact with the electrode material can be appropriately determined according to various physical properties of the electrode material (type of electrode active material, solid component concentration, composition of the electrolyte (viscosity, surface tension), etc.), the size and thickness of the formed electrode layer, etc.

[0246] And, it is preferable that the contact portion of the scraper with the electrode material is not easily adhered with the electrode material, and for example, it is preferable that at least the surface of the scraper exhibits mold release properties.

[0247] For example, as the doctor blade, it can be made of fluororesins such as polytetrafluoroethylene (PTFE), resins such as polyetheretherketone (PEEK), metals such as stainless steel, aluminum, iron, and cemented carbide, or ceramics.

[0248] Moreover, in order to impart mold release properties to the surface, the doctor blade may have a surface layer that exhibits mold release properties (for example, a surface layer containing a fluororesin, a surface layer containing silicon particles and a resin).

[0249] Furthermore, from the viewpoint of improving wear resistance, the doctor blade may have a high-hardness coating such as titanium oxide, titanium nitride (TiN), or tungsten carbide on a doctor blade body made of metal or ceramics.

[0250] (Roller)

[0251] The roller is a member whose outer peripheral surface can rotate. Regarding its size, material, etc., it can be appropriately determined according to various physical properties of the electrode material (such as the type of electrode active material, the solid component concentration, the composition of the electrolyte (viscosity, surface tension), etc.), the size, thickness, etc. of the formed electrode layer.

[0252] As the material constituting the outer peripheral surface of the roller, it can be the same as that of the doctor blade, and it may have a surface layer that exhibits mold release properties.

[0253] There is no particular limitation on the outer diameter of the roller. For example, it can be 20 mm to 30 mm.

[0254] Moreover, since the roller rotates, the friction coefficient between its outer peripheral surface and the electrode material can be regarded as 0. However, as a result, the adhesion to the electrode material may sometimes increase. Therefore, it is preferable to interpose a thin film between the electrode material and the outer peripheral surface of the roller.

[0255] [Electrode material supply mechanism]

[0256] As the supply mechanism for the electrode material to the current collector foil or the separator, in addition to the screw feeder described above, a disk feeder, a vibratory feeder, etc. can also be used.

[0257] Moreover, when the electrode material is applied to the current collector foil or the separator, a limiting frame can also be used from the viewpoint of making the application of the electrode material uniform.

[0258] Examples

[0259] Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to these.

[0260] In addition, each process in the following examples is carried out in a drying chamber (low dew point chamber) at 22°C.

[0261] [Preparation of Positive Electrode Active Material (P1)]

[0262] (1) 13.4 g of LiPF 6 (electrolyte) was mixed in a mixed solution of 45 g of ethylene carbonate (EC), 10 g of propylene carbonate (PC), and 45 g of diethyl carbonate (DEC), and then 2.3 g of vinylene carbonate (VC) was further mixed. 64 g was taken out of the obtained 115.7 g of the mixed solution and used as electrolyte X1.

[0263] (2) Using a mixer (Awatori Rentaro ARE-310, manufactured by THINKY CORPORATION, the same hereinafter), 2 g of a conductive additive (Ketjenblack: "Carbon ECP600JD" manufactured by Lion Specialty Chemicals Co., Ltd.) and 174 g of a positive electrode active material (lithium iron phosphate: "LFP NCO M121" manufactured by Aleees Corporation) were stirred at 1500 rpm (revolutions per minute) for 30 seconds to prepare a kneaded product Y1 (176 g).

[0264] (3) Electrolyte X1 (64 g) was added to the kneaded product Y1 (176 g), and the mixture was stirred at 1500 rpm for 120 seconds using a mixer (Awatori Rentaro ARE-310) to obtain a positive electrode active material (P1).

[0265] The obtained positive electrode active material (P1) is a Bingham fluid with a yield value of 45 kPa, and the volume ratio of the solid component to the liquid component is 48:52.

[0266] [Preparation of Positive Electrode Active Material (P2)]

[0267] (1) 43 g was taken out of the 115.7 g of the mixed solution obtained in (1) of the positive electrode active material (P1) and used as electrolyte X2.

[0268] (2) Using a mixer (Awatori Rentaro ARE-310), 2 g of a conductive additive (Ketjenblack: "Carbon ECP600JD" manufactured by Lion Specialty Chemicals Co., Ltd.) and 195 g of a positive electrode active material (lithium iron phosphate: "LFP NCO M121" manufactured by Aleees Corporation) were stirred at 1500 rpm for 30 seconds to prepare a kneaded product Y2 (197 g).

[0269] (3) Electrolyte X2 (43 g) was added to the kneaded material Y2 (197 g), and the mixture was stirred at 1500 rpm for 120 seconds using a mixer (Awatori Rentaro ARE-310) to obtain a positive electrode active material (P2).

[0270] The obtained positive electrode active material (P2) is a Bingham fluid with a yield value of 200 kPa, and the volume ratio of the solid component to the liquid component is 60:40.

[0271] [Preparation of negative electrode active material (P3)]

[0272] (1) Electrolyte X1 (64 g) identical to the electrolyte used in the positive electrode active material (P1) was prepared.

[0273] (2) A conductive additive (carbon black: "C-NERGY SUPERC45" manufactured by Imerys Graphite&Carbon) and a negative electrode active material ("MESOPHASEGRAPHITE POWDER A (MGP-A)" manufactured by China Steel Chemical Corporation) were weighed in a total amount of 159 g at a mass ratio of 2.7:63.4, and the two were stirred at 900 rpm for 18 seconds using a mixer (Awatori Rentaro ARE-310) to prepare a kneaded material Z1.

[0274] (3) Electrolyte X1 (64 g) was added to the kneaded material Z1 (159 g), and the mixture was stirred at 900 rpm for 30 seconds using a mixer (Awatori Rentaro ARE-310) to obtain a negative electrode active material (P3).

[0275] The obtained negative electrode active material (P3) is a Bingham fluid with a yield value of 20 kPa, and the volume ratio of the solid component to the liquid component is 52:48.

[0276] [Preparation of negative electrode active material (P4)]

[0277] (1) 50 g was taken out from the 115.7 g of the mixed solution obtained in (1) of the positive electrode active material (P1) and used as electrolyte X3.

[0278] (2) The conductive additive (carbon black: "C-NERGY SUPERC45" manufactured by Imerys Graphite&Carbon) and the negative electrode active material ("MESOPHASEGRAPHITE POWDER A (MGP-A)" manufactured by China Steel Chemical Corporation) were weighed in a total amount of 190 g such that the mass ratio was 2.7:63.4, and the two were stirred at 900 rpm for 18 seconds using a mixer (Awatori Rentaro ARE-310) to prepare a kneaded mixture Z2.

[0279] (3) Electrolyte X3 (50 g) was added to the kneaded mixture Z2 (190 g), and the mixture was stirred at 900 rpm for 30 seconds using a mixer (Awatori Rentaro ARE-310) to obtain an electrode material for the negative electrode (P4).

[0280] The obtained electrode material for the negative electrode (P4) is a Bingham fluid with a yield value of 150 kPa, and the volume ratio of the solid component to the liquid component is 68:32.

[0281] [Preparation of current collector foils (S1) and (S2)]

[0282] Current collector foil (S1): A current collector foil obtained by thermally bonding the thermally bondable layer of a PET film having a thermally bondable layer containing an ethylene-vinyl acetate copolymer (EVA) to the back surface of a positive current collector foil (aluminum foil, average thickness 20 μm, Ra 0.5 μm, EAA-218D, a carbon-coated product manufactured by Korea JCC).

[0283] Current collector foil (S2): A current collector foil obtained by thermally bonding the thermally bondable layer of a PET film having a thermally bondable layer containing an ethylene-vinyl acetate copolymer (EVA) to the back surface of a negative current collector foil (copper foil, average thickness 10 μm, Ra 0.55 μm, manufactured by Nippon Electro-Silicon Manufacturing Co., Ltd.).

[0284] In addition, Ra of the above current collector refers to the arithmetic mean roughness Ra on the formation surface of the electrode material film.

[0285] [Preparation of separator]

[0286] A polyethylene separator with a thickness of 20 μm (manufactured by Senior, porosity 47%) was prepared.

[0287] [Preparation of squeegee (B1)]

[0288] Squeegee (B1): A squeegee made of stainless steel

[0289] <Example 1>

[0290] In the first form, a battery was manufactured as follows.

[0291] Using the electrode layer forming apparatus 100A shown in Figure 1 (a), a positive electrode layer was formed of the positive electrode material (P1) on the aluminum foil of the current collector foil (S1) (process A). At this time, G L1 = G D1 . The size of the formed positive electrode layer was 540 mm × 500 mm, the thickness was 330 μm, and the solid component concentration was 48 vol%.

[0292] Next, a polyethylene separator was placed on the positive electrode layer.

[0293] Next, using the electrode layer forming apparatus 100B shown in Figure 1 (c), a negative electrode layer was formed of the negative electrode material (P3) on the separator (process B). At this time, G L2 = G D2 . The size of the formed negative electrode layer was 542 mm × 502 mm, the thickness was 345 μm, and the solid component concentration was 52 vol%.

[0294] Then, the copper foil of the current collector foil (S2) was placed in contact on the negative electrode layer (process C).

[0295] For the obtained laminate composed of a PET film / aluminum foil / positive electrode layer (lower layer) / separator / negative electrode layer (upper layer) / copper foil / PET film, pressing was performed as shown in Figure 1 (e), and the outer peripheral portion of the electrode layer was heat-sealed using a heat sealer.

[0296] Thereby, a battery was obtained.

[0297] <Example 2>

[0298] In the first - 2 form, a battery was manufactured as follows.

[0299] Using the electrode layer forming apparatus 100A shown in Figure 1 (a), a negative electrode layer was formed of the negative electrode material (P3) on the copper foil of the current collector foil (S2) (process A). At this time, G L1 = G D1 . The size of the formed negative electrode layer was 542 mm × 502 mm, the thickness was 345 μm, and the solid component concentration was 52 vol%.

[0300] Next, a polyethylene separator was placed on the negative electrode layer.

[0301] Next, using the electrode layer forming apparatus 100B as shown in Figure 1 (c), a positive electrode layer (process B) was formed on the separator with the positive electrode material (P1). At this time, G L2 =G D2 . The size of the formed positive electrode layer was 540 mm × 500 mm, the thickness was 330 μm, and the solid content concentration was 48 vol%.

[0302] Then, an aluminum foil of the current collector foil (S1) was placed in contact with the positive electrode layer (process C).

[0303] As shown in Figure 1 (e), the obtained laminate composed of a PET film / copper foil / negative electrode layer (lower layer) / separator / positive electrode layer (upper layer) / aluminum foil / PET film was pressed and heat-sealed using a heat sealer.

[0304] Thus, a battery was obtained.

[0305] <Example 3>

[0306] In the second - 1 form, a battery was manufactured as follows.

[0307] Using the electrode layer forming apparatus 100A as shown in Figure 1 (a), a positive electrode layer (process A) was formed on the aluminum foil of the current collector foil (S1) with the positive electrode material (P1). At this time, G L1 =G D1 . The size of the formed positive electrode layer was 540 mm × 500 mm, the thickness was 330 μm, and the solid content concentration was 48 vol%.

[0308] And, a stage having an adsorption mechanism identical to the stage shown in Figure 1 was prepared, and a separator was placed on the adsorption mechanism of this stage. Then, using the same electrode layer forming apparatus 100B as the electrode layer forming apparatus shown in Figure 1 (c), a negative electrode layer (process B) was formed on the separator with the negative electrode material (P3). At this time, G L2 =G D2 . The size of the formed negative electrode layer was 542 mm × 502 mm, the thickness was 345 μm, and the solid content concentration was 52 vol%.

[0309] The separator on which the negative electrode layer was formed was removed from the stage and placed on the positive electrode layer (process D1).

[0310] Then, a copper foil of the current collector foil (S2) was placed in contact with the negative electrode layer (process C).

[0311] As Figure 1 (e) shows, the laminate composed of PET film / aluminum foil / positive electrode layer (lower layer) / separator / negative electrode layer (upper layer) / copper foil / PET film obtained by pressing was heat-sealed using a heat sealer.

[0312] A battery was thus obtained.

[0313] <Example 4>

[0314] In the 2-2 form, a battery was manufactured in the following manner.

[0315] Using the electrode layer forming apparatus 100A as shown in Figure 1 (a), a negative electrode layer was formed from the negative electrode material (P3) on the copper foil of the current collector foil (S2) (process A). At this time, G L1 = G D1 . The size of the formed negative electrode layer was 542 mm × 502 mm, the thickness was 345 μm, and the solid component concentration was 52 vol%.

[0316] And, a stage having an adsorption mechanism identical to the stage shown in Figure 1 was prepared, and a separator was placed on the adsorption mechanism of this stage. Then, using the same electrode layer forming apparatus 100B as the electrode layer forming apparatus shown in Figure 1 (c), a positive electrode layer was formed from the positive electrode material (P1) on the separator (process B). At this time, G L2 = G D2 . The size of the formed positive electrode layer was 540 mm × 500 mm, the thickness was 330 μm, and the solid component concentration was 48 vol%.

[0317] The separator formed with the positive electrode layer was removed from the stage and placed on the negative electrode layer (process D2).

[0318] Then, the aluminum foil of the current collector foil (S1) was placed in contact on the positive electrode layer (process C).

[0319] As Figure 1 (e) shows, the laminate composed of PET film / copper foil / negative electrode layer (lower layer) / separator / positive electrode layer (upper layer) / aluminum foil / PET film obtained by pressing was heat-sealed using a heat sealer.

[0320] A battery was thus obtained.

[0321] <Comparative Example 1>

[0322] In the same manner as in Example 1, using as shown in Figure 1The electrode layer forming apparatus 100A shown in (a) formed a positive electrode layer on the aluminum foil of the current collector foil (S1) using the positive electrode material (P1).

[0323] And, in the same manner as in Example 2, using as Figure 1 the electrode layer forming apparatus 100A shown in (a), a negative electrode layer was formed on the copper foil of the current collector foil (S2) using the negative electrode material (P3).

[0324] After placing the separator on the positive electrode layer, the negative electrode layer formed on the current collector foil (S2) was inverted so that the negative electrode layer was placed on the separator.

[0325] When inverting the current collector foil (S2), a part of the negative electrode layer collapsed from the copper foil of the current collector foil (S2), and a laminate composed of a PET film / aluminum foil / positive electrode layer (lower layer) / separator / negative electrode layer (upper layer) / copper foil / PET film could not be obtained.

[0326] <Examples 5 - 8>

[0327] As shown in Table 1 below, the positive electrode material (P1) was replaced with the positive electrode material (P2), and the negative electrode material (P3) was replaced with the negative electrode material (P4). Except for this, batteries were manufactured in the same manner as in Examples 1 - 4, respectively.

[0328] <Example 9>

[0329] The positive electrode material (P1) was replaced with the positive electrode material (P2). Except for this, batteries were manufactured in the same manner as in Example 1, respectively.

[0330] <Example 10>

[0331] The negative electrode material (P3) was replaced with the positive electrode material (P4). Except for this, batteries were manufactured in the same manner as in Example 2, respectively.

[0332] <Example 11>

[0333] The positive electrode material (P1) was replaced with the positive electrode material (P2). Except for this, batteries were manufactured in the same manner as in Example 3, respectively.

[0334] <Example 12>

[0335] The negative electrode material (P3) was replaced with the positive electrode material (P4). Except for this, batteries were manufactured in the same manner as in Example 4, respectively.

[0336] [Evaluation of collapse]

[0337] Using a CCD camera and illumination, the collapse of the electrode layer formed in Process B (i.e., the negative electrode layer with a size of 542 mm × 502 mm as the upper layer or the positive electrode layer with a size of 540 mm × 500 mm) was observed from the upper side of the electrode layer and evaluated.

[0338] Since the electrode layer in the part covered by the current collector foil cannot be observed for collapse, the collapse of the electrode layer as the upper layer can be observed by observing the electrode material splashing around the current collector foil (around the electrode layer).

[0339] Regarding the observation itself, 728 images of the entire surface (the entire upper surface) of the electrode layer were taken with a field of view of 20 mm square.

[0340] Through the above method, the captured images (728 images) of the entire surface of the electrode were obtained, and the number of the captured images in which collapse was observed was counted. The ratio of the number of the captured images in which collapse was observed to the total number of the captured images (728 images) was obtained, and the formability was evaluated according to the following criteria. The results are shown in Table 1.

[0341] -Evaluation Criteria-

[0342] AA: The ratio of the number of the captured images in which collapse was observed is 1% or less.

[0343] A: The ratio of the number of the captured images in which collapse was observed exceeds 1% and is 3% or less.

[0344] B: The ratio of the number of the captured images in which collapse was observed exceeds 3% and is 5% or less.

[0345] C: The ratio of the number of the captured images in which collapse was observed exceeds 5% and is 10% or less.

[0346] D: The ratio of the number of the captured images in which collapse was observed exceeds 10%.

[0347] [Evaluation of In-Plane Uniformity of Thickness]

[0348] The thickness of the obtained electrode layer was measured in the following manner, and the in-plane uniformity of the thickness was evaluated.

[0349] The total thickness TA1 of the current collector foil placed on the stage and the electrode layer as the lower layer was measured using a multi-color laser coaxial displacement meter manufactured by KEYENCE CORPORATION. Additionally, regarding the measurement positions, the laminate was equally divided into six parts in the width direction ( Figure 1 the Y direction), and the central part was respectively divided along the length direction ( Figure 1The X-direction) was set to 500 mm. Then, the thickness TA2 of only the current collector foil was measured in advance using the same apparatus and measurement site as described above, and the measured value of TA2 of only the current collector foil was subtracted from the measured value of the total thickness TA1 of the current collector foil and the electrode layer obtained by the above method, thereby obtaining the thickness of the electrode layer as the lower layer.

[0350] Moreover, in the cases of Form 1-1 and 1-2, the total thickness TB1 of the electrode layer as the upper layer and the layer below this electrode layer (current collector foil, electrode layer as the lower layer, and separator) was measured using the apparatus and measurement site of the above method. Then, before forming the electrode layer as the upper layer, the thickness TB2 of the current collector foil, the electrode layer as the lower layer, and the separator was measured in advance using the same apparatus and measurement site as described above, and the measured value of TB2 was subtracted from the measured value of the total thickness TB1 obtained by the above method, thereby obtaining the thickness of the electrode layer as the upper layer.

[0351] Moreover, in the cases of Form 2-1 and 2-2, the total thickness TC1 of the separator placed on the stage and the electrode layer as the upper layer was measured using the apparatus and measurement site of the above method. Then, before forming the electrode layer as the upper layer, the thickness TC2 of only the separator was measured in advance using the same apparatus and measurement site as described above, and the measured value of TC2 was subtracted from the measured value of the total thickness TC1 obtained by the above method, thereby obtaining the thickness of the electrode layer as the upper layer.

[0352] Based on the obtained measured values, the rate of change in the thickness of the laminate was obtained in the following manner. Regarding the rate of change in thickness, the maximum value X obtained from the measured values was selected Max and the minimum value X Min in which the difference from the average value X Ave was larger, and it was calculated using the following formula 1.

[0353] Formula 1: Rate of change in thickness (%) = |Maximum value X Max or minimum value X Min - Average value X Ave |÷Average value X Ave ×100

[0354] Here, in Formula 1, the maximum value X Max is the maximum value among the measured values, the minimum value X Min is the minimum value among the measured values, and the average value X Ave is the arithmetic average of the measured values.

[0355] Based on the obtained value of the rate of change in thickness, the in-plane uniformity of the thickness was evaluated according to the following criteria.

[0356] - Criteria -

[0357] AA: The rate of change in thickness is 2% or less.

[0358] A: The rate of change in thickness exceeds 2% and is 3% or less.

[0359] B: The rate of change in thickness exceeds 3% and is 4% or less.

[0360] C: The rate of change in thickness exceeds 4% and is 5% or less.

[0361] D: The rate of change in thickness exceeds 5%.

[0362]

[0363] As shown in Table 1, in the method for manufacturing the battery of the embodiment, no collapse of the electrode layer was observed.

[0364] (Symbol description)

[0365] 10 - stage, 20 - adsorption mechanism, 30 - first current collector foil, 32 - resin film, 40 - first electrode layer, 50 - separator, 60 - second electrode layer, 70 - second current collector foil (with a resin film not shown), 100A, 100B - electrode layer forming device, 102 - restricting member, 104 - main screw, 106 - branch screw, 110 - pressing member, 120 - heat sealer, X - moving direction of the electrode layer forming device, Y - arranging direction of the restricting member.

[0366] The entire content of the invention of Japanese Patent Application 2022 - 183461 filed on November 16, 2022 is incorporated herein by reference.

[0367] All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each document, patent application, and technical standard were specifically and separately described by reference.

Claims

1. A method for manufacturing a battery, the battery sequentially having a first current collector foil, a first electrode layer, a separator, a second electrode layer, and a second current collector foil, the method for manufacturing the battery comprises: Step A of forming a first electrode layer on the first current collector foil using a first electrode material; Step B of forming a second electrode layer on the separator using a second electrode material; and Step C of placing the second current collector foil on the second electrode layer, wherein both the first electrode material and the second electrode material contain an electrode active material, a conductive additive, and an electrolytic solution, and the solid component concentration is 30% to 80% by volume.

2. The method for manufacturing a battery according to claim 1, wherein, Step A is a step of forming a positive electrode layer as the first electrode layer on a positive electrode current collector foil as the first current collector foil, Step B is a step of forming a negative electrode layer as the second electrode layer on the separator placed on the positive electrode layer, Step C is a step of placing a negative electrode current collector foil as the second current collector foil on the negative electrode layer.

3. The method for manufacturing a battery according to claim 1, wherein, Step A is a step of forming a negative electrode layer as the first electrode layer on a negative electrode current collector foil as the first current collector foil, Step B is a step of forming a positive electrode layer as the second electrode layer on the separator placed on the negative electrode layer, Step C is a step of placing a positive electrode current collector foil as the second current collector foil on the positive electrode layer.

4. The method for manufacturing a battery according to claim 1, wherein, Step A is a step of forming a positive electrode layer as the first electrode layer on a positive electrode current collector foil as the first current collector foil, Step B is a step of forming a negative electrode layer as the second electrode layer on the separator, Step C is a step of placing a negative electrode current collector foil as the second current collector foil on the negative electrode layer, the method for manufacturing the battery further includes Step D1 of placing the separator and the negative electrode layer formed on the separator together on the positive electrode layer.

5. The method for manufacturing a battery according to claim 1, wherein, Step A is a step of forming a negative electrode layer as the first electrode layer on a negative electrode current collector foil as the first current collector foil, Step B is a step of forming a positive electrode layer as the second electrode layer on the separator, Step C is a step of placing a positive electrode current collector foil as the second current collector foil on the positive electrode layer, the method for manufacturing the battery further includes Step D2 of placing the separator and the positive electrode layer formed on the separator together on the negative electrode layer.

6. The method for manufacturing a battery according to claim 1, wherein, Step A is a step of intermittently or continuously supplying the first electrode material to the first current collector foil and restricting the thickness of the supplied first electrode material to form the first electrode layer, When the mass of the first electrode material supplied to the first collector foil is G D1 [g], the mass of the formed first electrode layer is G L1 [g], satisfies G L1 ≤G D1 ≤G L1 ×1.

2.

7. The method for manufacturing a battery according to claim 1, wherein, Step B is a step of intermittently or continuously supplying the second electrode material to the separator and restricting the thickness of the supplied second electrode material to form the second electrode layer, When the mass of the second electrode material supplied to the diaphragm is set to G D2 [g] and the mass of the formed second electrode layer is set to G L2 [g], it satisfies G L2 ≤G D2 ≤G L2 ×1.2.

Images