Method for manufacturing all-solid-state battery, and laminate for manufacturing all-solid-state battery

Abstract

The present invention provides a method for manufacturing an all-solid-state battery and a laminate for manufacturing an all-solid-state battery in which, even when a short circuit occurs in a battery cell containing an Li metal or an Li alloy in a negative electrode during manufacture, it is possible to ensure a large current will not flow in the cell having the short circuit. The present invention comprises a lamination crimping step for pressing a laminate in which a negative electrode containing a lithium metal or a lithium alloy, a solid electrolyte layer, and a positive electrode are positioned to form an all-solid-state battery laminate in which a plurality of battery cells are laminated. Prior to performing the pressing in the lamination crimping step, an insulation member is detachably attached to a current collector of the negative electrode and / or the positive electrode. After performing the lamination crimping step and before performing a bonding step of bonding a tab lead to the current collector, the insulation member is removed from the collector.

Description

Manufacturing method of all-solid-state battery, laminate for manufacturing all-solid-state battery

[0001] The present invention relates to a method for producing an all-solid-state battery and a laminate for use in producing an all-solid-state battery.

[0002] Patent Document 1 discloses an all-solid-state battery including a positive electrode formed by laminating a first current collector layer and a first active material layer, a negative electrode formed by laminating a second current collector layer containing at least copper and a second active material layer, and a solid electrolyte layer disposed between the first active material layer and the second active material layer. In this all-solid-state battery, a second tab lead is joined to an end of the second current collector layer after lamination by a fastening means, and a removable insulating cover is provided on the second tab lead joined by the fastening means.

[0003] Japanese Patent Application Laid-Open No. 2023-149424

[0004] In an all-solid-state battery that contains lithium (Li) metal or a Li alloy in the negative electrode during manufacturing, there is a need for a technology that prevents a large current from flowing through a short-circuited battery cell (hereinafter also referred to as a short-circuited cell) even if a short circuit occurs in the battery cell during manufacturing.

[0005] The present invention has been made in view of the above circumstances, and aims to provide a method for manufacturing an all-solid-state battery that can prevent a large current from flowing through a short-circuited cell even if a short circuit occurs in a battery cell containing Li metal or a Li alloy in the negative electrode during manufacturing, and a laminate for use in manufacturing an all-solid-state battery.

[0006] A method for manufacturing an all-solid-state battery according to one aspect of the present invention includes a lamination and compression bonding step of pressing a laminate including a negative electrode containing lithium metal or a lithium alloy, a solid electrolyte layer, and a positive electrode to form an all-solid-state battery laminate including a plurality of stacked battery cells. Prior to the pressing step in the lamination and compression bonding step, an insulating member is removably attached to the current collector of at least one of the negative electrode and the positive electrode. After the lamination and compression bonding step, and prior to a joining step of joining a tab lead to the current collector, the insulating member is removed from the current collector.

[0007] According to one aspect of the present invention, it is possible to provide a method for manufacturing an all-solid-state battery and a laminate for manufacturing an all-solid-state battery, which can prevent a large current from flowing through a short-circuited cell even if a short circuit occurs in a battery cell containing Li metal or a Li alloy in the negative electrode during manufacturing.

[0008] FIG. 1 is a cross-sectional view showing an example of the configuration of an all-solid-state battery manufactured by a manufacturing method according to the first embodiment. FIG. 2 is a flowchart showing a method for manufacturing an all-solid-state battery according to the first embodiment. FIG. 3A is a plan view showing an example of attaching an insulating member to a positive electrode current collector. FIG. 3B is a cross-sectional view showing an example of attaching an insulating member to a positive electrode current collector. FIG. 4A is a plan view showing an example of attaching an insulating member to a negative electrode current collector 3. FIG. 4B is a cross-sectional view showing an example of attaching an insulating member to a negative electrode current collector 3. FIG. 5 is a schematic diagram for explaining in detail steps ST1 to ST6 of the flowchart shown in FIG. 2. FIG. 6 is a comparative example of the present invention, and is a diagram schematically showing the flow of current when current collectors come into contact with each other while an internal short circuit occurs in a battery cell. FIG. 7 is a flowchart showing an example of a lamination and pressure bonding process according to the second embodiment. FIG. 8 is a cross-sectional view showing an attachment example 1 of an insulating member according to the third embodiment. FIG. 9 is a cross-sectional view showing an attachment example 2 of an insulating member according to the third embodiment. FIG. 10 is a cross-sectional view showing an attachment example 3 of an insulating member according to the third embodiment. Fig. 11 is a cross-sectional view showing an attachment example 4 of an insulating member according to the third embodiment. Fig. 12 is a schematic diagram showing the relationship between the distance between current collectors of the same polarity and the thickness of the insulating member in the third embodiment. Fig. 13A is a plan view showing the relationship between the insulating member according to the third embodiment and the uncoated portion of the negative electrode current collector covered with the insulating member. Fig. 13B is a plan view and a cross-sectional view showing the relationship between the insulating member according to the third embodiment and the uncoated portion of the negative electrode current collector covered with the insulating member. Fig. 14 is a cross-sectional view showing the relationship between the distance between current collectors according to the third embodiment and the distance between the end of the coated portion and the insulating member.

[0009] An embodiment of the present invention (the present embodiment) will be described below. In the following drawings, identical or similar parts are designated by identical or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratios of each device and each component, and the like may differ from the actual ones. Therefore, specific thicknesses and dimensions should be determined with reference to the following description. It goes without saying that the dimensional relationships and ratios of parts included in the drawings may differ from one another. The definitions of directions such as up and down in the following description are merely for the convenience of explanation and do not limit the technical concept of the present invention. For example, if an object is rotated 90 degrees and observed, up and down are read as being converted to left and right, and if it is rotated 180 degrees and observed, up and down are read as being reversed.

[0010] <Embodiment 1> (Configuration Example) Fig. 1 is a cross-sectional view showing a configuration example of an all-solid-state battery 1 manufactured by a manufacturing method according to the present embodiment 1. As shown in Fig. 1, the all-solid-state battery 1 manufactured by the manufacturing method according to the present embodiment 1 includes an anode 4 having an anode layer 2 and an anode current collector 3, a cathode 7 having a cathode layer 5 and a cathode current collector 6, a solid electrolyte layer 8 disposed between the anode 4 and the positive electrode 7, an anode tab lead 11 joined to the anode current collector 3, and a cathode tab lead 12 joined to the cathode current collector 6.

[0011] The negative electrode layer 2 is provided on both surfaces in the thickness direction of the negative electrode current collector 3 (top and bottom surfaces in FIG. 1 ). For example, the negative electrode 4 can be obtained by pressure-bonding lithium (Li) metal or a Li alloy to both surfaces of the negative electrode current collector 3 as the negative electrode layer 2. For the negative electrode current collector 3 and the negative electrode tab lead 11, for example, a metal foil such as copper (Cu), a Cu alloy, nickel, or a nickel alloy can be used, but is not limited to these. The negative electrode layer 2 is made of Li metal or a Li alloy. More specifically, examples of Li alloys include, but are not limited to, a Li-Mg alloy, a Li-Si alloy, a Li-Al alloy, a Li-Zn alloy, a Li-Sn alloy, and a Li-Bi alloy.

[0012] The positive electrode layer 5 is provided on both surfaces in the thickness direction of the positive electrode current collector 6 (top and bottom surfaces in FIG. 1 ). For example, a positive electrode 7 can be obtained by preparing a slurry by weighing and mixing predetermined amounts of a positive electrode active material, a sulfide solid electrolyte, a conductive additive, a binder, and an organic solvent, applying the slurry to both surfaces of the positive electrode current collector 6, and then drying the slurry. The positive electrode current collector 6 and the positive electrode tab lead 12 can be made of, for example, aluminum (Al) foil, but are not limited to these. The positive electrode layer 5 can be made of, for example, manganese dioxide, sulfide, or fluoride, but are not limited to these.

[0013] The solid electrolyte layer 8 may be made of any material as long as it functions as an electrolyte layer in a secondary battery. For example, the solid electrolyte layer 8 may include a sulfide solid electrolyte. Examples of sulfide solid electrolytes include materials containing Li, phosphorus (P), sulfur (S), and a halide. For example, the solid electrolyte layer 8 can be obtained by weighing and mixing predetermined amounts of the sulfide solid electrolyte, a binder, and an organic solvent to prepare a slurry, which is then applied to a substrate and dried.

[0014] The negative electrodes 4 and positive electrodes 7 are alternately stacked with solid electrolyte layers 8 interposed therebetween to form an all-solid-state battery stack 10. The solid electrolyte layer 8 is interposed between the negative electrode 4 and the positive electrode 7 to form one battery cell 9. The all-solid-state battery stack 10 includes a plurality of battery cells 9. In each battery cell 9, charging and discharging are performed by exchange of alkali metal ions (e.g., Li ions) between the negative electrode 4 and the positive electrode 7 via the solid electrolyte layer 8.

[0015] (Manufacturing Method) Next, a manufacturing method of the all-solid-state battery 1 according to the first embodiment will be described. FIG. 2 is a flowchart showing a manufacturing method of the all-solid-state battery 1 according to the first embodiment. Note that other steps may be included between the steps in the flowchart of FIG. 2. FIGS. 3A and 3B are a plan view and a cross-sectional view showing an example of attaching an insulating member 35 to a positive electrode current collector 6. The cross-section of the plan view shown in FIG. 3A taken along line X1-X1′ corresponds to the cross-section of FIG. 3B. FIGS. 4A and 4B are a plan view and a cross-sectional view showing an example of attaching an insulating member 35 to a negative electrode current collector 3. The cross-section of the plan view shown in FIG. 4A taken along line X2-X2′ corresponds to the cross-sectional view of FIG. 4B. FIG. 5 is a schematic diagram for explaining in detail steps ST1 to ST6 of the flowchart shown in FIG. 2. The all-solid-state battery 1 is manufactured using various types of equipment, such as an equipment for stacking the negative electrode 4, the positive electrode 7, and the solid electrolyte layer 8, a press equipment for pressing the all-solid-state battery stack 10, an equipment for performing a discharge process on the all-solid-state battery stack 10, and a welding equipment for welding the current collector and the tab lead, etc. Hereinafter, these equipment will be collectively referred to as manufacturing equipment.

[0016] In step ST1 of FIG. 2 , the manufacturing apparatus places a cathode 7 with a solid electrolyte layer 8. For example, the cathode 7 with a solid electrolyte layer 8 is placed, in which the solid electrolyte layer 8 is pre-laminated on the cathode layer 5. The manufacturing method involves stacking the cathode 7 and the solid electrolyte layer 8 so that the cathode layer 5 and the solid electrolyte layer 8 are in contact with each other and applying pressure. After pressing, the substrate of the solid electrolyte layer 8 is removed, thereby transferring the solid electrolyte layer 8 to the cathode 7. The cathode 7 with the solid electrolyte layer 8 can be obtained by this manufacturing method. Note that the manufacturing method according to the first embodiment is not limited to this. For example, the solid electrolyte layer 8 may be provided on the anode 4 instead of the cathode 7. In this case, step ST1 simply becomes a step of placing the cathode 7, and step ST3, described later, becomes a step of placing the anode 4 with the solid electrolyte layer 8. Alternatively, the solid electrolyte layer 8 may be prepared separately from the cathode 7 and the anode 4. In this case, for example, a step of disposing the solid electrolyte layer 8 may be provided between the step of disposing the positive electrode 7 (step ST1) and the step of disposing the negative electrode 4 (step ST3).

[0017] Next, in step ST2 of FIG. 2 , the manufacturing apparatus removably attaches an insulating member 35 to the positive electrode 7. The insulating member 35 is a component made of an insulating material. For example, the insulating member 35 is a cover made of insulating resin formed by injection molding, and is molded into a shape that can be detachably attached to the uncoated portion of the current collector. Examples of insulating resins include polypropylene (PP) and polyethylene terephthalate (PET). As shown in FIGS. 3A and 3B , the positive electrode current collector 6 has a coated portion 61 coated with the positive electrode layer 5 and an uncoated portion 62 that is not coated with the positive electrode layer 5. The manufacturing apparatus removably attaches the insulating member 35 to the uncoated portion 62 of the positive electrode current collector 6. The uncoated portion 62 of the positive electrode current collector 6 protrudes from the laminate 10′ and is exposed from the positive electrode layer 5. The manufacturing apparatus removably attaches insulating member 35 to at least a part of uncoated portion 62, and covers both surfaces (upper surface 62a, lower surface 62b) in the thickness direction of uncoated portion 62, end surface 62c located at the tip in the protruding direction from laminate 10′ (left-right direction in FIGS. 3A and 3B), and side surface 62d with insulating member 35. Side surface 62d is, for example, an end surface in the width direction (up-down direction in FIG. 3A) perpendicular to the protruding direction.

[0018] Next, in step ST3 of Fig. 2 , the manufacturing equipment places the negative electrode 4 at a position facing the positive electrode 7 with the solid electrolyte layer 8 interposed therebetween in the stacking direction. Next, in step ST4 of Fig. 2 , the manufacturing equipment removably attaches an insulating member 35 to the negative electrode 4. For example, as shown in Figs. 4A and 4B , the negative electrode current collector 3 has a coated portion 31 coated with the negative electrode layer 2 and an uncoated portion 32 not coated with the negative electrode layer 2. The manufacturing equipment removably attaches the insulating member 35 to the uncoated portion 32 of the negative electrode current collector 3. The uncoated portion 32 of the negative electrode current collector 3 protrudes from the laminate 10' and is exposed from the negative electrode layer 2. The manufacturing apparatus removably attaches an insulating member 35 to at least a part of the uncoated portion 32, and covers both surfaces (upper surface 32a, lower surface 32b) in the thickness direction of the uncoated portion 32, an end surface 32c located at the tip in the protruding direction from the laminate 10' (the left-right direction in FIGS. 4A and 4B), and a side surface 32d with the insulating member 35. The side surface 32d is, for example, an end surface in the width direction (the up-down direction in FIG. 4A) perpendicular to the protruding direction.

[0019] Steps ST1 to ST4 in FIG. 2 are the stacking process for one battery cell. Steps ST1 to ST4 are repeated a preset number of times (i.e., a predetermined number of times). The predetermined number of times is the number of stacked battery cells 9 (see FIG. 1). As a result, as shown in FIG. 5, an unbonded laminate 10' is formed in which an anode 4 containing Li metal or a Li alloy as an anode layer 2, a solid electrolyte layer 8, and a cathode 7 are repeatedly arranged in the stacking direction. Next, in step ST5 in FIG. 2, the manufacturing apparatus performs a pressurizing process on the unbonded laminate 10'. For example, as shown in FIG. 5, the manufacturing apparatus presses the laminate 10' at a press pressure (i.e., a first surface pressure) P1 at least in the stacking direction. The press pressure P1 shown in FIG. 5 is equal to or greater than the yield stress of Li metal, e.g., 5 MPa or greater. The yield stress of Li metal refers to the stress at which plasticity of Li metal begins. This pressing causes the negative electrode layer 2 and the solid electrolyte layer 8, and the solid electrolyte layer 8 and the positive electrode layer 5, to be pressure-bonded together at high pressure, thereby forming the all-solid-state battery stack 10.

[0020] By this molding, the anode layer 2 made of Li metal or Li alloy is pressure-bonded to the solid electrolyte layer 8. Therefore, each battery cell 9 included in the all-solid-state battery stack 10 is formed in a charged state. For example, each battery cell 9 included in the all-solid-state battery stack 10 is formed in a state of 100% SOC (State of Charge) or a high SOC (for example, 95%, 90%, or 85%). Next, in step ST6 of FIG. 2 , the manufacturing apparatus performs an internal short-circuit inspection on the all-solid-state battery stack 10. For example, as shown in FIG. 5 , the manufacturing apparatus inspects whether or not a short circuit exists between the anode 4 and the cathode 7 for each of the plurality of battery cells 9 included in the all-solid-state battery stack 10. 5 , the insulating member 35 is removed from the battery cell 9 to be inspected, a resistance measuring device 23 is connected to the negative electrode current collector 3 and the positive electrode current collector 6, and a DC voltage is applied between the negative electrode current collector 3 and the positive electrode current collector 6 to measure the value of the current flowing through the battery cell 9. The internal resistance of the battery cell 9 is detected from this measurement value.

[0021] For example, if the detected internal resistance is equal to or greater than a preset value, the negative electrode current collector 3 and the positive electrode current collector 6 are insulated from each other, and the manufacturing device (inspection device) determines that there is no abnormality (i.e., OK). On the other hand, if the detected internal resistance is lower than a preset value (i.e., NG), there is a possibility that a short circuit has occurred between the negative electrode current collector 3 and the positive electrode current collector 6, and the manufacturing device determines that there is an abnormality (i.e., NG). An all-solid-state battery stack 10 including a battery cell 9 determined to have an abnormality is treated as a defective product, and the manufacturing process is terminated.

[0022] Next, in step ST7 of FIG. 2 , if the insulating members 35 remain on at least some of the positive electrode current collectors 6 or at least some of the negative electrode current collectors 3, the manufacturing equipment removes the insulating members 35 from the positive electrode current collectors 6 or the negative electrode current collectors 3. If all of the insulating members 35 have been removed in the internal short-circuit inspection process of step ST6, step ST7 is skipped and the process proceeds to step ST8. In step ST8 of FIG. 2 , the manufacturing equipment performs tab joining. For example, the manufacturing equipment joins the negative electrode current collector 3 to the negative electrode tab lead 11 (see FIG. 1 ). The manufacturing equipment also joins multiple positive electrode current collectors 6 to the positive electrode tab lead 12 (see FIG. 1 ). This joining is, for example, by welding. The welding method is not particularly limited, but examples include welding using an ultrasonic welder and laser welding. Through the above processes, the all-solid-state battery 1 shown in FIG. 1 is completed.

[0023] In the manufacturing method according to the first embodiment, a sealing process, a discharging process, and a charging process may be performed following step ST8 of the flowchart shown in FIG. 2 . In the sealing process, the manufacturing apparatus seals the all-solid-state battery stack 10 with an insulating sheet, excluding the negative electrode tab lead 11 and the positive electrode tab lead 12. The joint (welded portion) between the negative electrode tab lead 11 and the negative electrode current collector 3 and the joint (welded portion) between the positive electrode tab lead 12 and the positive electrode current collector 6 are also sealed with an insulating sheet (not shown). In the discharging process, the manufacturing apparatus performs a discharging operation on the all-solid-state battery stack 10 formed in a charged state. For example, a discharging operation is performed on all battery cells 9 included in the all-solid-state battery stack 10 via the negative electrode tab lead 11 and the positive electrode tab lead 12 shown in FIG. 1 . In this discharging operation, Li ions move from the negative electrode 4 to the positive electrode 7 via the solid electrolyte layer 8 in each battery cell 9 and are occluded in the positive electrode layer 5. When a discharge operation is performed, the Li metal or Li alloy in the anode layer 2 decreases as the discharge progresses. When the discharge progresses to an SOC of 0%, the Li metal or Li alloy in the anode layer 2 is almost gone. In the charging step, the manufacturing equipment performs an initial charging operation on the discharged all-solid-state battery stack 10. This charging operation is performed via the anode tab lead 11 and the cathode tab lead 12. In this charging operation, in each battery cell 9, Li ions that had been occluded in the cathode layer 5 move to the anode current collector 3 via the solid electrolyte layer 8, and Li metal or Li alloy is deposited as the anode layer 2.

[0024] Effect of First Embodiment As described above, the manufacturing method of the all-solid-state battery 1 according to the first embodiment includes a lamination and compression step of pressing a laminate 10′ in which a negative electrode 4 containing Li metal or a Li alloy, a solid electrolyte layer 8, and a positive electrode 7 are repeatedly arranged in one direction (stacking direction) at least in the stacking direction to form an all-solid-state battery laminate 10 in which a plurality of battery cells 9 are stacked in the stacking direction, and a joining step of joining tab leads (e.g., a negative electrode tab lead 11, a positive electrode tab lead 12) to current collectors (e.g., a negative electrode current collector 3, a positive electrode current collector 6) of at least one of the negative electrode 4 and the positive electrode 7. Before pressing in the lamination and compression step, an insulating member 35 is removably attached to the current collector. After the lamination and compression step and before the joining step, the insulating member 35 is removed from the current collectors.

[0025] This makes it possible to prevent the current collector of one battery cell 9 adjacent to the other battery cell 9 in the stacking direction from coming into contact with the current collector of the other battery cell 9 and becoming electrically conductive when forming the all-solid-state battery stack 10 (for example, in the stacking and pressing process) that includes Li metal or Li alloy in the negative electrode 4. This makes it possible to prevent the formation of an external parallel circuit due to contact between the current collectors. Even if a short circuit occurs in the battery cells 9 during the stacking and pressing process, it is possible to prevent a large current from flowing through the short-circuited battery cell (i.e., the short-circuited cell). This effect will be described in more detail using a comparative example.

[0026] FIG. 6 is a comparative example of the present invention, and is a diagram schematically illustrating the flow of current I when current collectors come into contact with each other when an internal short circuit occurs in a battery cell 109. During the lamination and compression process in which a negative electrode containing Li metal or a Li alloy, a solid electrolyte layer, and a positive electrode are stacked and pressed, an internal short circuit may occur in the battery cell 109. FIG. 6 illustrates a case in which a short circuit occurs between the negative electrode 4 and the positive electrode 7 in one battery cell (short-circuited cell) 109S among the multiple battery cells 109 included in the all-solid-state battery stack 110. In this state, when the negative electrode current collectors 3 come into contact with each other and the positive electrode current collectors 6 come into contact with each other, an external parallel circuit is formed. In this external parallel circuit, current I flows from all of the non-shorted battery cells 109 to the short-circuited cell 109S, resulting in a large current. A large current flowing through the short-circuited cell 109S may cause the short-circuited cell 109S to generate a large amount of heat, which is undesirable.

[0027] In contrast, in the manufacturing method according to the first embodiment, an insulating member 35 is placed on the uncoated portions of the current collectors (for example, the uncoated portion 32 of the negative electrode current collector 3 and the uncoated portion 62 of the positive electrode current collector 6), and the uncoated portions 32, 62 are insulated. This makes it possible to prevent the formation of an external parallel circuit due to contact between adjacent current collectors in the stacking direction in the stacking pressure bonding process. Even if a short-circuited cell is included in the all-solid-state battery stack 10, the short-circuited cell is insulated from the other battery cells 9 by the insulating member 35, so that no current flows into the short-circuited cell from the other battery cells 9. Since no large current flows in the short-circuited cell and only a current equivalent to the charge capacity of the short-circuited cell flows, heat generation in the short-circuited cell can be suppressed.

[0028] Furthermore, the manufacturing method according to the first embodiment may further include an inspection step between the lamination and pressure bonding step and the bonding step, in which an internal short circuit of the battery cell 9 is inspected. After the inspection step and before the bonding step, the insulating member 35 may be removed from the current collector. This makes it possible to inspect whether or not the all-solid-state battery stack 10 includes a short-circuited cell, while preventing the formation of an external parallel circuit due to contact between the current collectors.

[0029] In the laminate for manufacturing an all-solid-state battery according to the first embodiment (for example, the laminate 10′ or the all-solid-state battery laminate 10), an anode 4 containing Li metal or a Li alloy, a solid electrolyte layer 8, and a cathode 7 are repeatedly arranged in one direction (stacking direction). A tab lead is not joined to an uncoated portion of the current collector of at least one of the anode 4 and the cathode 7, which is not coated with an electrode layer. An insulating member 35 is removably attached to the uncoated portion. This makes the laminate for manufacturing an all-solid-state battery suitable for use in the manufacturing method according to the present embodiment. Even if a short-circuited cell occurs in the stacking and compression bonding process, it is possible to prevent a large current from flowing through the short-circuited cell.

[0030] (Variation of Embodiment 1) In the above-described embodiment 1, the insulating member 35 is attached to each of the positive electrode current collector 6 and the negative electrode current collector 3. However, this embodiment is not limited to this. In this embodiment, the insulating member 35 may be attached to one of the positive electrode current collector 6 and the negative electrode current collector 3, and the insulating member 35 may not be attached to the other. Even in this embodiment, the insulating member 35 is located between one current collector and the other current collector adjacent in the stacking direction on the side where the insulating member 35 is attached, thereby preventing contact between adjacent current collectors in the stacking direction. This prevents the formation of an external parallel circuit due to contact between the current collectors. Therefore, even if a short-circuited cell occurs, it is possible to prevent a large current from flowing into the short-circuited cell.

[0031] <Embodiment 2> In the above-described embodiment 1, as shown in FIG. 2, the positive electrode 7 is disposed, the insulating member 35 is attached to the disposed positive electrode 7, and then the negative electrode 4 is disposed, and the insulating member 35 is attached to the disposed negative electrode 4. However, in this embodiment, the order in which the insulating member 35 is attached to the positive electrode 7 and the negative electrode 4 is not limited to this. FIG. 7 is a flowchart showing an example of a lamination and compression bonding process according to embodiment 2. As shown in FIG. 7, in embodiment 2 as well, the manufacturing apparatus disposes the positive electrode 7 (first positive electrode; an example of the "first electrode" in the present invention) with a solid electrolyte layer in step ST11, disposes the negative electrode 4 (first negative electrode; an example of the "second electrode" in the present invention) in step ST12, disposes the positive electrode 7 (second positive electrode) with a solid electrolyte layer in step ST13, and disposes the negative electrode 4 (second negative electrode) in step ST14. Then, after repeating steps ST11 to ST14 a predetermined number of times, the manufacturing apparatus performs the pressurizing process of step ST5 shown in FIG. 2. The subsequent steps are the same as those in embodiment 1.

[0032] In the second embodiment, the insulating member 35 is attached to the first positive electrode 7 between the placement of the first positive electrode 7 and the placement of the second positive electrode 7 (i.e., between the end of step ST11 and the start of step ST13). The insulating member 35 may be attached to the first positive electrode 7 after the placement of the first negative electrode 4. The insulating member 35 is removably attached to the uncoated portion 62 of the positive electrode current collector 6 of the first positive electrode 7, on the surface facing the second positive electrode 7. The insulating member 35 is attached to the first negative electrode 4 between the placement of the first negative electrode 4 and the placement of the second negative electrode 4 (i.e., between the end of step ST12 and the start of step ST14). The insulating member 35 may be attached to the second negative electrode 4 after the placement of the second positive electrode 7. An insulating member 35 is removably attached to the uncoated portion 32 of the negative electrode current collector 3 of the first negative electrode 4, on the surface facing the second negative electrode 4. In the second embodiment, the same effects as those in the first embodiment can be achieved.

[0033] <Embodiment 3> In the above-described embodiment 1, both surfaces (e.g., upper and lower surfaces) of the uncoated portion 62 of the positive electrode current collector 6 and both surfaces (e.g., upper and lower surfaces) of the uncoated portion 32 of the negative electrode current collector 3 are covered with the insulating member 35, as shown in FIGS. 3B, 4B, and 5. However, in the present embodiment, the insulating member 35 may be attached to only one surface of each of the uncoated portions 62, 32, rather than both surfaces (both surfaces) in the thickness direction. That is, the insulating member 35 may cover one of the upper and lower surfaces and not the other. In embodiment 3, the insulating member 35 may be an insulating sheet, rather than the insulating cover formed by injection molding as described in embodiment 1. Examples of insulating materials constituting the sheet include insulating resins such as PP and PET. Alternatively, the insulating sheet is not limited to insulating resin, and may be made of low-dust-generating insulating paper or a composite material in which paper is coated with an insulating resin. The insulating sheet may be provided with a low-adhesion adhesive layer that is peelable from the uncoated portion, or may not have an adhesive layer. From the viewpoint of workability in attaching and detaching the insulating sheet to and from the current collector, the insulating sheet is preferably stronger (less flexible) than the current collector.

[0034] Fig. 8 is a cross-sectional view showing a first attachment example of the insulating member 35 according to the third embodiment. In the lamination and pressure bonding step described with reference to Fig. 1 or 7, the manufacturing apparatus may attach the insulating member 35 only to the upper surface 62a of the uncoated portion 62 of the positive electrode current collector 6, as shown in Fig. 8. Similarly, the insulating member 35 may be attached only to one surface in the thickness direction of the uncoated portion 32 of the negative electrode current collector 3, for example, the upper surface 32a.

[0035] 9 is a cross-sectional view showing a second attachment example of the insulating member 35 according to the third embodiment. As shown in Fig. 9, the manufacturing apparatus may attach the insulating member 35 so as to continuously cover the uncoated portion 62 of the positive electrode current collector 6 from the upper surface 62a to the end surface 62c. Similarly, the insulating member 35 may be attached so as to continuously cover the uncoated portion 32 of the negative electrode current collector 3 from the upper surface 32a to the end surface 62c.

[0036] 10 is a cross-sectional view showing a third example of attachment of the insulating member 35 according to the third embodiment. As shown in FIG. 10 , the manufacturing apparatus may attach the insulating member 35 only to the lower surface 62 b of the uncoated portion 62 of the positive electrode current collector 6. Similarly, the insulating member 35 may be attached only to the upper surface 32 a of the uncoated portion 32 of the negative electrode current collector 3.

[0037] 11 is a cross-sectional view showing a fourth example of attachment of the insulating member 35 according to the third embodiment. As shown in Fig. 11 , the manufacturing apparatus may attach the insulating member 35 so as to continuously cover the uncoated portion 62 of the positive electrode current collector 6 from the lower surface 62b to the end surface 62c. Similarly, the insulating member 35 may be attached so as to continuously cover the uncoated portion 32 of the negative electrode current collector 3 from the lower surface 32b to the end surface 62c.

[0038] 12 is a schematic diagram showing the relationship between the distance T1 between current collectors of the same polarity and the thickness T2 of the insulating member in Embodiment 3. As shown in Fig. 12, the distance T1 between current collectors is, for example, the distance between a first negative electrode current collector 3 (an example of the "first electrode" of the present invention) and a second negative electrode current collector 3 (an example of the "second electrode" of the present invention) that are adjacent in the stacking direction in the all-solid-state battery stack 10 after the stacking and compression bonding step shown in Fig. 2 has been performed. This distance T1 between current collectors is also the total thickness of each layer (negative electrode layer 2, solid electrolyte layer 8, positive electrode 7, solid electrolyte layer 8, and negative electrode layer 2) located between the first negative electrode current collector 3 and the second negative electrode current collector 3.

[0039] In the third embodiment, it is preferable that the inter-collector distance T1 and the thickness T2 of the insulating member 35 satisfy the relationship T1 ≥ T2. This prevents the insulating member 35 from interfering with the compression bonding of the stack 10' in the stacking and compression bonding step shown in Fig. 2. If T1 < T2, the insulating member 35 will push up or down the negative electrode current collector 3 of other battery cells adjacent in the stacking direction, making it difficult to compress the stack 10'.

[0040] 12, the inter-collector distance T1 is shown as the distance between adjacent negative electrode current collectors 3 in the stacking direction, but this is merely an example. When an insulating member 35 is attached to a positive electrode current collector 6, the inter-collector distance T1 may be the distance between adjacent positive electrode current collectors 6 in the stacking direction. That is, the inter-collector distance T1 may be the total thickness of each layer (positive electrode layer 5, solid electrolyte layer 8, negative electrode 4, solid electrolyte layer 8, positive electrode layer 5) located between the first positive electrode current collector 6 and the second positive electrode current collector 6, and in this case, it is also preferable that T1≧T2. This prevents the insulating member 35 from interfering with the compression bonding of the stack 10′.

[0041] 13A and 13B are a plan view and a cross-sectional view showing the relationship between the insulating member 35 according to the third embodiment and the uncoated portion 32 of the negative electrode current collector 3 covered by the insulating member 35. FIG. 13B shows a cross-section of the plan view shown in FIG. 13A taken along line X3-X3′. As shown in FIG. 13A , the insulating member 35 preferably has a larger area than the uncoated portion 32 of the negative electrode current collector 3 (an example of a “current collector” according to the present invention) in a plan view from the stacking direction. This makes it easier for the insulating member 35 to cover and insulate the end (including the end surface 32 c) of the negative electrode current collector 3. This makes it possible to more reliably prevent the ends of adjacent negative electrode current collectors 3 in the stacking direction from contacting each other and becoming conductive.

[0042] As shown in FIGS. 13A and 13B , the distance between the end of the insulating member 35 and the end of the uncoated portion 32 of the negative electrode current collector 3 (e.g., end surface 32c) is defined as A, and the thickness of the uncoated portion 32 is defined as t. The distance A is preferably equal to or greater than the thickness t of the uncoated portion 32. In other words, it is preferable to satisfy the relationship A≧t. This more reliably prevents the end of the uncoated portion 32 from contacting the end of another uncoated portion 32 adjacent in the stacking direction and establishing electrical continuity. The insulating member 35 may be flexible enough that the portion extending beyond the uncoated portion 32 (the portion of distance A) bends downward under its own weight. In this case, the portion of distance A sags, covering the end surface 32c (the portion of thickness t) of the uncoated portion 32.

[0043] FIG. 14 is a cross-sectional view showing the relationship between the inter-collector distance T1 and the distance L between the end of the coated portion 31 and the insulating member 35 according to the third embodiment. As shown in FIG. 12 , the inter-collector distance (e.g., the distance between the first negative electrode current collector 3 and the second negative electrode current collector 3) is designated as T1. Also, as shown in FIG. 14 , the distance between the end of the coated portion 31 coated with the negative electrode layer 2 and the insulating member 35 is designated as L. The distance L is preferably equal to or less than half the inter-collector distance T1. In other words, it is preferable to satisfy the relationship L≦T1×½. This makes it possible to more reliably prevent the negative electrode current collectors 3 from contacting each other and becoming electrically conductive, even when adjacent negative electrode current collectors 3 are closest to each other in the stacking direction.

[0044] 13A, 13B, and 14 illustrate the relationship between the negative electrode current collector 3 and the insulating member 35, but this relationship may also be applied to the positive electrode current collector. In this case, the positive electrode current collector 6 is an example of the "current collector" of the present invention.

[0045] <Other Embodiments> As described above, the present invention has been described with reference to embodiments and modifications. However, the descriptions and drawings that form part of this disclosure should not be understood as limiting the present invention. Various alternative embodiments and modifications will be apparent to those skilled in the art from this disclosure. For example, in embodiments of the present invention, insulating members may be removably attached to some, but not all, of the negative electrode current collectors 3 constituting the laminate 10′. For example, insulating members 35 may be removably attached to every other negative electrode current collector 3 in the stacking direction. The same applies to the positive electrode current collector 6. Furthermore, in not only Embodiment 3 but also Embodiments 1 and 2, the insulating member 35 may be the insulating sheet described in Embodiment 3 rather than an insulating cover. In Embodiments 1 and 2, insulating sheets may be removably attached to both surfaces (e.g., top and bottom surfaces) of the uncoated portion of the current collector as the insulating member 35. As such, the present technology naturally includes various embodiments not described herein. Various omissions, substitutions, and / or modifications of components may be made without departing from the spirit and scope of the above-described embodiments. Furthermore, the effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0046] DESCRIPTION OF SYMBOLS 1... all-solid-state battery, 2... negative electrode layer, 3... negative electrode current collector, 4... negative electrode, 5... positive electrode layer, 6... positive electrode current collector, 7... positive electrode, 8... solid electrolyte layer, 9, 109... battery cell, 10'... laminate, 10, 110... all-solid-state battery laminate, 11... negative electrode tab lead, 12... positive electrode tab lead, 23... resistance measuring device, 31, 61... coated portion, 32, 62... uncoated portion, 32a, 62a... upper surface, 32b, 62b... lower surface, 32c, 62c... end surface, 32d, 62d... side surface, 35... insulating member, 109S... short-circuit cell

Claims

1. A method for manufacturing an all-solid-state battery, comprising: a lamination and compression step of pressing a laminate in at least one direction, in which a negative electrode containing lithium metal or a lithium alloy, a solid electrolyte layer, and a positive electrode are repeatedly arranged in the same direction, to form an all-solid-state battery laminate in which a plurality of battery cells are stacked in the same direction; and a joining step of joining a tab lead to a current collector of at least one of the negative electrode and the positive electrode, in which an insulating member is removably attached to the current collector before the pressing in the lamination and compression step, and the insulating member is removed from the current collector after the lamination and compression step is performed and before the joining step is performed.

2. The method for manufacturing an all-solid-state battery according to claim 1, further comprising an inspection step between the lamination and pressure bonding step to inspect the battery cell for internal short circuits, and removing the insulating member from the current collector after the inspection step and before the bonding step.

3. The method for manufacturing an all-solid-state battery according to claim 1 or 2, further comprising a step of preparing the laminate, wherein, during the step between arranging a first electrode as the electrode and arranging a second electrode having the same polarity as the first electrode and adjacent to the first electrode in the one direction, the insulating member is removably attached to an uncoated portion of a current collector of the first electrode that is not coated with an electrode layer.

4. The method for manufacturing an all-solid-state battery according to claim 3, wherein the insulating member is attached to the uncoated portion on the surface facing the second electrode, between the placement of the first electrode and the placement of the second electrode.

5. The method for producing an all-solid-state battery according to claim 1 or 2, wherein the insulating member is attached to one surface in the thickness direction of an uncoated portion of the current collector that is not coated with an electrode layer.

6. The method for manufacturing an all-solid-state battery according to claim 5, wherein the electrodes include a first electrode and a second electrode having the same polarity as the first electrode and adjacent to the first electrode in the one direction, and in the all-solid-state battery stack after the pressing, when a total thickness of each layer located between the current collector of the first electrode and the current collector of the second electrode is T1 and a thickness of the insulating member is T2, T1 is equal to or greater than T2.

7. The method for manufacturing an all-solid-state battery according to claim 1 or 2, wherein the insulating member is attached to an uncoated portion of the current collector that is not coated with an electrode layer, and the insulating member has a larger area than the uncoated portion in a plan view from the one direction.

8. The method for producing an all-solid-state battery according to claim 7, wherein the distance between the end of the insulating member and the end of the uncoated portion is equal to or greater than the thickness of the uncoated portion.

9. The method for manufacturing an all-solid-state battery according to claim 1 or 2, wherein the insulating member is provided in an uncoated portion of the current collector that is not coated with an electrode layer, the electrodes include a first electrode and a second electrode that has the same polarity as the first electrode and is adjacent to the first electrode in the one direction, and wherein L is the distance between the insulating member and an end of the coated portion that is coated with the electrode layer, and T1 is the total thickness of each layer located between the current collector of the first electrode and the current collector of the second electrode in the all-solid-state battery stack after the pressing, and L is not more than 1 / 2 of T1.

10. A laminate for manufacturing an all-solid-state battery, in which a negative electrode containing lithium metal or a lithium alloy, a solid electrolyte layer, and a positive electrode are repeatedly arranged in one direction, a tab lead is not joined to an uncoated portion of a current collector of at least one of the negative electrode and the positive electrode, which is not coated with an electrode layer, and an insulating member is removably attached to the uncoated portion.

Images