Battery manufacturing method

Abstract

To stabilize the battery quality.SOLUTION: A battery manufacturing method includes the steps of measuring a predetermined weight of each of a plurality of electrode materials A to C and placing them in a container 31, placing the plurality of electrode materials A to C placed in the container 31 into a supplying machine 40, supplying the plurality of electrode materials A to C from the supplying machine 40 to a twin-screw kneader 50, and kneading the plurality of electrode materials A to C in the twin-screw kneader 50.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Japanese Patent Application Laid-Open Publication No. 2011-233380 discloses a manufacturing apparatus for electrode composite slurry for secondary batteries. The manufacturing apparatus is connected to a measuring device. The measuring device measures the materials corresponding to the respective components constituting the powder battery material in a supply section of the manufacturing apparatus so that the material has a predetermined blend ratio, and then charges the materials into the supply section of the manufacturing apparatus. This configuration is said to enable the powder battery material to be continuously supplied to the supply section at the predetermined blend ratio.

[0003] In an embodiment disclosed in JP 2011-233380 A, a metering feeder is used as a measuring device. Raw materials are supplied to a manufacturing apparatus from two metering feeders. One of the two metering feeders supplies an active material, and the other supplies a conductive additive. The metering feeders supply a predetermined amount of raw material to a continuous manufacturing apparatus. The metering feeder includes a raw material hopper for storing the raw material, a load cell for measuring the raw material, a spiral feeder for feeding the raw material toward the feed section of the manufacturing apparatus, and a connecting cylinder communicating with the powder feeding end of the spiral feeder. The connecting cylinder is erected from the periphery of the raw material receiving port of the manufacturing apparatus. Each of the spiral feeders of the two metering feeders feeds a predetermined amount of raw material. The raw material is supplied into the casing of the manufacturing apparatus via the connecting cylinder. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-233380 Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors want to stabilize the quality of the battery. [Means for solving the problem]

[0006] The battery manufacturing method disclosed herein includes the steps of weighing out a plurality of electrode materials by a predetermined weight and placing them in a container, placing the plurality of electrode materials in the container into a feeder, feeding the plurality of electrode materials from the feeder to a multi-screw kneader, and kneading the plurality of electrode materials in the multi-screw kneader.

[0007] This battery manufacturing method ensures stable battery quality. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a flowchart of a method for manufacturing a battery. [Figure 2] FIG. 2 is a schematic diagram of the slurry production apparatus 10. [Figure 3] FIG. 3 is a schematic diagram of the feeder 40. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the technology disclosed herein will be described below with reference to the drawings. The embodiment described here is, of course, not intended to limit the present invention. The drawings are schematic and do not necessarily reflect the actual product. Furthermore, the same reference numerals are appropriately used for components and parts that perform the same function, and redundant explanations will be omitted where appropriate.

[0010] <Battery manufacturing method> Fig. 1 is a flowchart of a battery manufacturing method. As shown in Fig. 1, the battery manufacturing method includes step S1 of measuring a plurality of electrode materials by a predetermined weight and placing the materials in a container, step S3 of placing the plurality of electrode materials in the container into a feeder, step S5 of feeding the plurality of electrode materials from the feeder to a multi-screw kneader, and step S7 of kneading the plurality of electrode materials in the multi-screw kneader. The battery manufacturing method will be described below using a method of manufacturing a battery using a slurry manufacturing apparatus 10 as an example.

[0011] <Slurry manufacturing device 10> FIG. 2 is a schematic diagram of a slurry production apparatus 10. In FIG. 2, the direction in which materials are supplied or conveyed is indicated by an arrow. In the slurry production apparatus 10, an electrode material and a solvent are mixed together to produce an electrode composite slurry. In this embodiment, the slurry production apparatus 10 produces a positive electrode composite slurry containing a positive electrode composite. As shown in FIG. 2, the slurry production apparatus 10 includes a material supply device 20, a reversing feeder 30, a supply device 40, and a twin-screw kneader 50.

[0012] First, a plurality of electrode materials A to C are weighed to predetermined weights in the material supply device 20 and placed in the container 31 (S1).

[0013] <Material supply device 20> The material supply device 20 includes feeders 21 to 23 and measuring devices 27 to 29. The feeders 21 to 23 supply powder electrode materials A to C, respectively. Known devices capable of supplying a fixed amount of powder material can be used as the feeders 21 to 23. The feeders 21 to 23 can be a circle feeder, a screw feeder, a rotary feeder, a belt feeder, or the like.

[0014] The feeders 21 and 23 contain electrode materials A and C. In this embodiment, the electrode materials A and C are lithium nickel cobalt manganese composite oxides as positive electrode active materials. Here, the electrode material A has an average particle diameter of 4 μm and a tap density of 2.2 g / cm. 3Electrode material C is a lithium nickel cobalt manganese composite oxide with an average particle size of 17 μm and a tap density of 2.4 g / cm 3 The electrode material B is a lithium nickel cobalt manganese composite oxide. The feeder 22 contains an electrode material B. In this embodiment, the electrode material B is polyvinylidene difluoride (PVDF) as a binder. Here, the electrode material B has a density of 1 g / cm 3 It is PVDF.

[0015] The positive electrode active material and binder are not particularly limited, and various materials conventionally used as positive electrode active materials and binders for lithium ion secondary batteries can be used without particular limitations. For example, the positive electrode active material may be lithium nickel oxide (e.g., LiNiO2), lithium cobalt oxide (e.g., LiCoO2), lithium manganese oxide (e.g., LiMn2O4), or a composite thereof (e.g., LiNi 0.5 Mn 1.5 O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 Particles of oxides (lithium transition metal oxides) containing lithium and transition metal elements as constituent metal elements, such as lithium manganese phosphate (LiMnPO4) and lithium iron phosphate (LiFePO4), and particles of phosphates containing lithium and transition metal elements as constituent metal elements, such as lithium manganese phosphate (LiMnPO4) and lithium iron phosphate (LiFePO4), can be used. Examples of binders that can be used include acrylic resins such as (meth)acrylic acid ester polymers, vinyl halide resins such as polyvinylidene fluoride (PVDF), and polyalkylene oxides such as polyethylene oxide (PEO). In addition, from the viewpoint of ease of stirring and kneading in subsequent processes, the density (or tap density) of the powder electrode material supplied from the feeder should be 0.5 to 3.0 g / cm. 3 It is preferable that:

[0016] The weighing devices 27 to 29 are devices for weighing the electrode materials A to C supplied from the feeders 21 to 23. The weighing devices 27 to 29 each carry a container 31 that holds the electrode materials A to C supplied from the feeders 21 to 23. The containers 31 are arranged on an index table 25. The index table 25 can accommodate a plurality of containers 31 (six in the embodiment shown in FIG. 2). The index table 25 is rotated in a predetermined direction at a predetermined timing by a drive device 25b connected to an axis 25a. As the index table 25 rotates, the container 31 sequentially moves to positions where the electrode materials A to C are supplied from the feeders 21 to 23. At this time, the weighing devices 27 to 29 measure the weights of the electrode materials A to C supplied to the container 31, respectively. When the container 31 moves to the positions where the electrode materials A to C are supplied, the other containers 31 also move in the same direction and at the same timing. When the material is supplied to one container 31, the material is sequentially supplied to other containers 31 following that container 31.

[0017] In the weighing devices 27 to 29, the electrode materials A to C are weighed by predetermined weights, respectively. As the weighing devices 27 to 29, for example, a balance, a load cell, etc. can be used. First, the container 31 moves to a position where the electrode material A is supplied. The container 31 is set in the weighing device 27. The weighing device 27 measures the weight of the electrode material A supplied from the feeder 21 to the container 31. Next, the container 31 moves to a position where the electrode material B is supplied. The container 31 is set in the weighing device 28. The weighing device 28 measures the weight of the electrode material B supplied from the feeder 22 to the container 31. Next, the container 31 moves to a position where the electrode material C is supplied. The container 31 is set in the weighing device 29. The weighing device 29 measures the weight of the electrode material C supplied from the feeder 23 to the container 31.

[0018] The weights of the electrode materials A to C measured by the measuring devices 27 to 29 are appropriately set depending on the composition of the target electrode mixture slurry. The weight ratio of the positive electrode active material, binder, and conductive material contained in the positive electrode mixture slurry can be set to, for example, approximately positive electrode active material:binder:conductive material = 96.0 to 99.0:0.5 to 2.0:0.5 to 2.0. In this embodiment, the weight ratio of the positive electrode active material, binder, and conductive material contained in the positive electrode mixture slurry is set to positive electrode active material:binder:conductive material = 97.5:1.0:1.5. The measuring devices 27 to 29 measure the electrode materials A to C in each container 24 to 26 so that the weight ratio of electrode material A (positive electrode active material):electrode material B (binder):electrode material C (positive electrode active material) = 48.75:1.0:48.75. In this embodiment, acetylene black (AB) is used as the conductive material. Acetylene black as a conductive material is placed in a paste state into a twin-screw kneader 50, which will be described later.

[0019] In this embodiment, electrode material A, electrode material B, and electrode material C are placed in container 31 in this order. Electrode material A (positive electrode active material), electrode material B (binder), and electrode material C (positive electrode active material) are placed in container 31 in this order from the bottom of container 31 toward the opening. In step S1 of placing materials in container 31, a positive electrode active material with a relatively high density is placed in container 31, followed by a binder with a relatively low density in container 31, and then another positive electrode active material with a relatively high density is placed in container 31.

[0020] The method for putting the electrode materials A to C into the reversing feeder 30 is not particularly limited. For example, the electrode materials A to C may be weighed in different containers and then put into the container 31. The order in which the electrode materials A to C are put into the container 31 is not limited to the above-mentioned form. For example, the electrode materials A to C may be put into the container 31 in the order of electrode material C, electrode material B, and electrode material A. The order in which the materials are put into the container 31 may be set as appropriate depending on the physical properties, number, etc. of the materials.

[0021] <Reversing machine 30> The reversing inserter 30 includes an arm 32 and a drive unit 33. The arm 32 is configured to be able to grip the container 31. The drive unit 33 is a device that drives the arm 32 around a fulcrum 32a set on the arm 32 as an axis. The drive unit 33 can be realized by, for example, a motor, a sprocket, etc.

[0022] The electrode materials A to C contained in the container 31 are fed into the feeder 40 by the inverting feeder 30 (S3).

[0023] In this embodiment, the drive device 33 rotates the arm 32 toward the feeder 40 around the fulcrum 32a. The drive device 33 stops the arm 32 after it has rotated approximately 180 degrees. As a result, the opening of the container 31 is inverted from an upward-facing state (shown by a dashed line in FIG. 2) to a downward-facing state. The positions of the inverting feeder 30 and the feeder 40 are set so that the container 31 is inverted above the hopper 41 (see FIG. 3) of the feeder 40. An inlet 41a (see FIG. 3) through which the materials are fed is provided at the top of the hopper 41. The electrode materials A to C fall from the inverted container 31 and are fed into the hopper 41 from the inverted container 31 through the inlet 41a. The electrode materials A to C are fed from the container 31 to the hopper 41 in the following order: electrode material C, electrode material B, and electrode material A. Note that a device other than the inverting feeder 30 may be used to feed the electrode materials A to C into the feeder 40. For example, a lifting type inverting machine may be used in which the container is lifted and inverted along a lifting axis.

[0024] After the electrode materials A to C have been placed in the feeder 40, the arm 32 is driven in the reverse direction by the drive device 33. The container 31 is returned to the index table 25. Thereafter, the container 31 moves as the index table 25 rotates. At this time, a new container 31 containing the weighed electrode materials A to C is sent to the reversing feeder 30. By repeating this process, the containers 31 containing the electrode materials A to C are sent to the reversing feeder 30 at regular intervals.

[0025] The electrode materials A to C are intermittently charged into the supply machine 40 by the reversing charger 30. The weighing of the electrode materials A to C by the material supply device 20 and the reversing charging of the electrode materials A to C by the reversing charger 30 can be performed in conjunction with each other. In this embodiment, the charging of the electrode materials A to C into the container 31 by the reversing charger 30 and the reversing charging from the reversing charger 30 to the supply machine 40 are repeated in a cycle of approximately 30 seconds. Therefore, a substantially constant amount of the electrode materials A to C is charged into the supply machine 40 at substantially constant intervals. In other words, step S1 of weighing the electrode materials A to C and charging them into the container 31 and step S3 of charging the electrode materials A to C from the container 31 into the supply machine 40 are repeatedly performed. The electrode materials A to C, the weight ratios of which have been adjusted, can be supplied into the supply machine 40 at predetermined intervals. Since the electrode materials A to C are weighed each time they are fed into the feeder 40, the weight ratio of the electrode materials A to C in the feeder 40 is likely to be stable. Even when a plurality of electrode materials A to C are used, the compounding ratio of the mixed powder material fed into the feeder 40 is likely to be guaranteed.

[0026] <Feeder 40> FIG. 3 is a schematic diagram of the feeder 40. In FIG. 3, the direction in which the electrode materials A to C are fed and the direction in which the agitator 45 rotates are indicated by arrows. FIG. 3 also shows a schematic cross section of the feeder 40 along its height direction. In this embodiment, a constant volume feeder (hereinafter referred to as constant volume feeder 40) that continuously supplies a predetermined amount of material is used as the feeder 40. As shown in FIG. 3, the constant volume feeder 40 includes hoppers 41 and 42, blades 43 and 44, an agitator 45, and a drive device 46. In this embodiment, the constant volume feeder 40 is a so-called circle feeder.

[0027] The hoppers 41 and 42 are portions that store the electrode materials A to C. In this embodiment, the constant volume feeder 40 is provided with two hoppers 41 and 42. The hopper 41 is provided with a blade 43 and a stirring member 45. The hopper 42 is provided with a blade 44. A drive device 46 is connected to the blades 43 and 44.

[0028] The hopper 41 is generally cylindrical. An inlet 41a is formed in the top of the hopper 41, through which the electrode materials A to C are introduced. An opening 41b1 is formed in a portion of the bottom 41b of the hopper 41. The hopper 41 is connected to the hopper 42 via the opening 41b1. An intermediate plate 41c is provided above the opening 41b1. The intermediate plate 41c is generally disk-shaped except for an opening 41c1 formed in a portion of the plate. The intermediate plate 41c is sized to cover at least the upper portion of the opening 41b1. The opening 41c1 of the intermediate plate 41c and the opening 41b1 of the bottom 41b are formed at different positions in a plan view. The opening 41c1 of the intermediate plate 41c and the opening 41b1 of the bottom 41b are provided on opposite sides of the shaft 43a of the blade 43, which is provided in the approximate center of the bottom 41b.

[0029] The blade 43 includes a shaft 43a and feed blades 43b and 43c attached to the shaft 43a. The shaft 43a extends upward from approximately the center of the bottom portion 41b. The feed blade 43b extends radially outward from the shaft 43a along the upper surface of the intermediate plate 41c. In this embodiment, two feed blades 43b extend from the shaft 43a. The feed blades 43c extend radially outward from the shaft 43a along the bottom portion 41b. In this embodiment, four feed blades 43c extend from the shaft 43a. A drive unit 46 is connected to the shaft 43a. The drive unit 46 is, for example, a motor. The drive unit 46 may be connected to the shaft 43a via a reducer, a transmission, or the like. The drive unit 46 rotates the shaft 43a, causing the feed blades 43b and 43c to rotate.

[0030] In this embodiment, an agitator 45 is provided on the upper portion of the shaft 43a of the blade 43. Therefore, the agitator 45 rotates in conjunction with the rotation of the blade 43. The agitator 45 includes a shaft 45a and an agitator plate 45b. The shaft 45a extends upward from the upper end of the shaft 43a of the blade 43. Two spiral agitator plates 45b are wound around the shaft 45a. Each of the two spiral agitator plates 45b is wound around the shaft 45a from the base end to the tip end. The agitator plate 45b is sized to cover the entire shaft 45a except for the ends of the intermediate plate 41c and the bottom 41b. The agitator 45 is not limited to this form and may be, for example, a rod-shaped member or a plate-shaped member attached to the shaft 45a. The angle, number, etc. of the agitator plates 45 are not particularly limited.

[0031] The hopper 42 is generally cylindrical and shorter than the hopper 41. The hopper 42 is provided with blades 44. The blades 44 include a shaft 44a and a feed blade 44b attached to the shaft 44a. The shaft 44a extends upward from approximately the center of the bottom 42a. The feed blade 44b curves and extends radially outward from the shaft 44a along the bottom 42a. The shape of the feed blade 44b facilitates stable feeding of the electrode materials A to C. The height of the feed blade 44b decreases radially outward. In this embodiment, four feed blades 44b extend from the shaft 44a. The shape, number, etc. of the feed blades 44b are not particularly limited and can be appropriately determined depending on the type of material, etc. A drive unit 46 is connected to the shaft 44a. Therefore, the blades 43 and 44 rotate at the same time. A discharge port 42a1 is formed in the bottom 42a of the hopper 42. The supply of the electrode materials A to C to the constant volume feeder 40 and the discharge from the constant volume feeder 40 will be described below.

[0032] By inverting the container 31 above the hopper 41, the electrode materials A to C introduced through the introduction port 41a are introduced into the constant volume feeder 40 in the reverse order of the order in which they were introduced into the container 31 (in this embodiment, the order of electrode materials C, B, A). The introduced electrode materials A to C are agitated by the rotating agitator 45. This makes it easier for the electrode materials A to C to be uniformly dispersed within the constant volume feeder 40. As the agitator 45 rotates, the electrode materials A to C are fed toward the outer wall 41d of the hopper 41. The electrode materials A to C that have reached the intermediate plate 41c are gradually fed toward the opening 41c1 of the intermediate plate 41c by the feed blade 43b.

[0033] The electrode materials A to C that pass through the opening 41c1 of the intermediate plate 41c fall onto the bottom 41b of the hopper 41. The electrode materials A to C are gradually fed toward the opening 41b1 of the bottom 41b by the feed blade 43c. The electrode materials A to C are fed to the hopper 42 through the opening 41b1. The electrode materials A to C fed to the hopper 42 are gradually fed toward the discharge port 42a1 by the feed blade 44b and discharged from the constant volume feeder 40. The amount of the electrode materials A to C discharged from the discharge port 42a1 is set according to the rotation speed of the blades 43 and 44. The blades 43 and 44 are rotated at a constant speed by the drive device 46, so that an approximately constant amount of the electrode materials A to C can be continuously discharged from the discharge port 42a1. The rotation speed of the blades 43 and 44 is not particularly limited, but can be set appropriately according to the intervals at which the electrode materials A to C are reversely charged, the amount, and the like.

[0034] In this way, in constant volume feeder 40, by rotating blades 43, 44 and stirring member 45, the electrode materials A to C in hoppers 41, 42 are stirred and the electrode materials A to C are discharged from constant volume feeder 40 simultaneously.

[0035] The electrode materials A to C are discharged from the discharge port 42a1 of the constant volume feeder 40 and supplied to the twin-screw kneader 50 (S5).

[0036] <Twin-screw kneader 50> The twin-screw kneader 50 (see FIG. 2) is an apparatus for kneading electrode materials A to C while applying shear force to them. The electrode materials A to C are kneaded while being conveyed through the twin-screw kneader 50 along the conveying direction. As shown in FIG. 2, the twin-screw kneader 50 includes a barrel 51, a shaft 52 provided within the barrel 51, and a drive device 53 for driving the shaft 52. The twin-screw kneader 50 may be provided with a thermometer for measuring the temperature of the material within the barrel 51, a chiller for adjusting the temperature of the material within the barrel 51, and the like. Note that the apparatus for kneading the electrode materials is not limited to the twin-screw kneader and may be, for example, a multi-screw kneader such as a four-screw kneader.

[0037] The barrel 51 is cylindrical and has a space therein for containing electrode materials, a solvent, and the like. One end of the barrel 51 is provided with a powder supply port 51a through which electrode materials A to C are supplied. The powder supply port 51a is connected to an outlet 42a1 of the constant volume feeder 40. A plurality of solvent supply ports 51b are provided downstream of the powder supply port 51a. A solvent supply device 55 is connected to the solvent supply port 51b. A monopump for maintaining a constant discharge rate may be connected to the solvent supply device 55. A constant discharge rate of the solvent is continuously supplied from the solvent supply port 51b. For example, water, N-methyl-2-pyrrolidone (NMP), or the like is used as the solvent. A paste inlet 51c is provided downstream of the plurality of solvent supply ports 51b. A paste supply device 56 is connected to the paste inlet 51c. Similar to the solvent supply device 55, the paste supply device 56 may be connected to a mono pump for maintaining a constant discharge rate. The mono pump may be provided with a flow meter for measuring the flow rates of the supplied solvent and paste. To stabilize the discharge rate, the rotation of the mono pump rotor may be controlled according to the flow rate measured by the flow meter. A constant discharge rate of paste is continuously supplied from the paste inlet 51c. In this embodiment, a paste-like conductive material (acetylene black in this embodiment) is introduced from the paste inlet 51c. In this manner, the materials for the positive electrode composite slurry are supplied into the barrel 51 in the order of electrode materials A to C, the solvent, and the conductive material. An outlet 51d is provided downstream of the paste inlet 51c. The outlet 51d is provided at the end of the barrel 51 opposite the powder supply port 51a. The completed positive electrode composite slurry is discharged from the outlet 51d.

[0038] A shaft 52 extending in the conveying direction is provided within the barrel 51. A screw 52a and a paddle 52b are provided on the shaft 52. A plurality of screws 52a and paddles 52b are provided along the conveying direction. The screws 52a and paddles 52b are provided on the outer circumferential surface of the shaft 52. The screw 52a has spirally wound blades. The paddle 52b is a plate-like member with its wide surface facing the conveying direction. Although not particularly limited, the paddle 52b has a polygonal shape (e.g., a triangle, a square, a hexagon, etc.) with curved corners. The side circumferential surface of the paddle 52b may also be curved. A predetermined gap is formed between the side circumferential surface of the paddle 52b and the inner circumferential surface of the barrel 51.

[0039] The driving device 53 may be a motor or the like that drives the shaft 52 to rotate. As the shaft 52 rotates, the screw 52a and the paddle 52b rotate in the circumferential direction of the shaft 52. The material in the barrel 51 is pushed by the blades of the screw 52a and transported in the transport direction. A shear force is applied to the material in the barrel 51 between the side circumferential surface of the paddle 52b and the inner circumferential surface of the barrel 51. The twin-screw kneader 50 may be provided with a pressure gauge that measures the pressure in the barrel 51. The driving of the driving device 53 may be controlled so that the pressure in the barrel 51 measured by the pressure gauge falls within a required pressure range.

[0040] The electrode materials A to C are kneaded using the above-mentioned twin-screw kneader 50 (S7).

[0041] The electrode materials A to C stirred in the constant volume feeder 40 are supplied from the powder supply port 51a into the barrel 51 of the twin-screw kneader 50. The electrode materials A to C are continuously supplied into the barrel 51 at approximately constant amounts per unit time by the constant volume feeder 40.

[0042] The electrode materials A to C are conveyed in the conveying direction by the screw 52a. The electrode materials A to C are conveyed while being subjected to shear force as they pass between the side circumferential surface of the paddle 52b and the inner circumferential surface of the barrel 51. The electrode materials A to C conveyed inside the barrel 51 are mixed with a solvent supplied from a solvent supply port 51b. The solvent is introduced into the barrel 51 separately from multiple solvent supply ports 51b provided along the conveying direction. Therefore, the electrode materials A to C and the solvent are mixed in stages. This makes it less likely that unevenness will occur in the mixed materials. The materials conveyed inside the barrel 51 (here, the electrode materials A to C and the solvent) are mixed with a paste-like conductive material. The paste-like conductive material is introduced into the barrel 51 through a paste inlet 51c. The electrode materials A to C, the solvent, and the conductive material are conveyed while being mixed, and a positive electrode composite slurry is completed. The produced positive electrode composite slurry is discharged from a discharge port 51d.

[0043] A battery can be manufactured using the produced positive electrode mixture slurry by a known method. For example, the positive electrode mixture slurry is applied to both sides of a positive electrode current collector and dried. This is cut to a predetermined size and rolled using a roll press to prepare a positive electrode sheet with a positive electrode active material layer on both sides of the positive electrode current collector. A negative electrode mixture slurry is produced, and a negative electrode sheet with a negative electrode active material is prepared using a procedure similar to that used to prepare the positive electrode sheet. The positive electrode sheet and the negative electrode sheet are laminated with a separator sheet interposed between them to produce an electrode body. The electrode body is then housed in a battery case to produce a battery assembly. An electrolyte is poured into the battery assembly, and initial charging and aging are performed to produce a battery.

[0044] The present inventors wish to improve the uniformity of the materials contained in the electrode mixture slurry in order to stabilize the quality of batteries. To stabilize the quality of batteries, it is necessary to precisely adjust the mixing ratio of the materials contained in the electrode mixture slurry. Furthermore, according to the inventors' findings, by kneading the materials in the limited space inside the barrel of a multi-shaft kneader, the materials can be mixed while applying high shear force and diluted with a solvent, etc. As a result, a slurry with high material uniformity is produced. However, for example, the materials contained in the electrode mixture slurry may contain materials that are difficult to uniformly disperse in the electrode mixture slurry. Examples of materials that are difficult to uniformly disperse include binders and thickeners. In order to uniformly disperse these materials in the electrode mixture slurry, they must be kneaded with high shear force. However, when high shear force is applied to the materials in the multi-shaft kneader, the load on the shaft may also increase. If the shaft of the multi-shaft kneader is long, there is a concern that the shaft may not be able to withstand the load.

[0045] In the above-described embodiment, the process includes step S1 of weighing out a plurality of electrode materials A to C by a predetermined weight and placing them in container 31; step S3 of feeding the plurality of electrode materials A to C from container 31 to constant volume feeder 40; step S5 of feeding the plurality of electrode materials A to C from constant volume feeder 40 to twin-screw kneader 50; and step S7 of kneading the plurality of electrode materials A to C in twin-screw kneader 50. Each of electrode materials A to C is weighed out by a predetermined weight and placed in container 31, which is then placed in constant volume feeder 40. Therefore, the weight ratio of electrode materials A to C in constant volume feeder 40 is precisely adjusted. Electrode materials A to C, whose weight ratios are precisely adjusted, are continuously fed to twin-screw kneader 50 at a substantially constant amount per unit time. This facilitates kneading electrode materials A to C, adjusted to the desired mixing ratio, in twin-screw kneader 50. As a result, a slurry in which the materials are uniformly dispersed is easily prepared, resulting in stable battery quality. The electrode materials A to C are placed in a container 31 and then fed into the twin-screw kneader 50 all at once.

[0046] In the above-described embodiment, the electrode materials A to C are supplied from the constant volume feeder 40 to the powder supply port 51a of the twin-screw kneader 50. In other words, the electrode materials A to C are supplied collectively from one location to the twin-screw kneader 50. Therefore, the lengths of the barrel 51 and shaft 52 of the twin-screw kneader 50 can be shortened compared to, for example, a slurry production apparatus including a multi-screw kneader in which the electrode materials are supplied separately to multiple locations. By shortening the shaft 32, the load on the shaft 32 is reduced even when a high shear force is applied to the electrode materials A to C. As a result, the electrode materials can apply a high shear force to A to C, making it easier to uniformly disperse the materials contained in the slurry.

[0047] In addition, the step S1 of weighing out a plurality of electrode materials A to C by a predetermined weight and placing them in the container 31 may include a step of weighing the electrode materials A to C and a step of placing the weighed electrode materials A to C in the container 31.

[0048] In the above-described embodiment, the constant volume feeder 40 is a circle feeder including blades 43, 44 and a drive device 46 that rotates and drives the blades 43, 44. By using the circle feeder, the electrode materials A to C are continuously supplied to the twin-screw kneader 50. This can stabilize the supply amounts of the electrode materials A to C. Furthermore, the equipment can be made smaller than when, for example, a screw feeder or the like is used.

[0049] In the embodiment described above, constant volume feeder 40 further includes a stirring member 45. Supplying step S5 includes stirring the electrode materials A to C placed in constant volume feeder 40. This allows the electrode materials A to C to be preliminarily mixed within constant volume feeder 40 before being kneaded in twin-screw kneader 50. This makes it easier to uniformly disperse the electrode materials A to C contained in the positive electrode mixture slurry. In addition, stirring member 45 is attached to blades 43 of constant volume feeder 40. Therefore, there is no need to provide separate equipment for stirring the electrode materials A to C, and the equipment can be made smaller.

[0050] In the above-described embodiment, the plurality of electrode materials A to C include a first electrode material (in this embodiment, PVDF as electrode material B) and a second electrode material (in this embodiment, positive electrode active materials as electrode materials A and C) having a density higher than that of the first electrode material. In the step of placing the materials in the container 31, a portion of the second electrode material (electrode material A) is placed in the container 31, followed by the first electrode material (electrode material B), and then the remainder of the second electrode material (electrode material C) is placed in the container 31. In the container 31, the electrode material B, which has a relatively low density, is sandwiched between the electrode materials A and C, which have a relatively high density. This can reduce the flying up of the electrode material B when the electrode materials A to C are placed in the container 31 and when the electrode materials A to C are placed from the container 31 to the constant volume feeder 40. As a result, the weight ratio of the electrode materials A to C supplied to the twin-screw kneader 50 is likely to be stable.

[0051] Although the method for producing a positive electrode composite slurry has been described as an example here, the present invention is not limited to this. The slurry producing apparatus 10 may also produce a negative electrode composite slurry.

[0052] The negative electrode mixture slurry may contain, for example, a negative electrode active material, a thickener, and a binder. The materials contained in the negative electrode mixture slurry are not particularly limited, and various materials conventionally used as materials for lithium-ion secondary batteries can be used without particular limitation. Examples of the negative electrode active material include carbon materials such as artificial graphite, natural graphite, amorphous carbon, and composites thereof (e.g., amorphous carbon-coated graphite), as well as materials that form alloys with lithium, such as silicon (Si), and lithium-storing compounds such as silicon compounds (e.g., SiO). Examples of the thickener include carboxymethyl cellulose (CMC). Examples of the binder include styrene butadiene rubber (SBR). The weight ratio of the negative electrode active material, thickener, and binder contained in the negative electrode mixture slurry may be set to, for example, approximately 96.0 to 99.0:0.5 to 2.0:0.5 to 2.0 (negative electrode active material:thickener:binder).

[0053] When producing a negative electrode composite slurry, containers 24 and 26 of material supply device 20 may contain a negative electrode active material, and container 25 may contain CMC as a thickener. SBR as a binder may be added from paste inlet 51c, similar to the paste-like acetylene black used when producing a positive electrode composite slurry. The process for producing a negative electrode composite slurry is similar to the process for producing a positive electrode composite slurry, and therefore a detailed description thereof will be omitted.

[0054] The technology disclosed herein has been described in various ways. Unless otherwise specified, the embodiments and the like described herein do not limit the present invention. Furthermore, the technology disclosed herein can be modified in various ways, and the components and processes described herein can be omitted or combined as appropriate, unless a particular problem arises.

[0055] This specification also includes the disclosures described in the following sections.

[0056] Section 1: a step of measuring a plurality of electrode materials by a predetermined weight and placing the electrode materials in a container; placing the plurality of electrode materials contained in the container into a feeder; supplying the plurality of electrode materials from the supply machine to a multi-shaft kneader; kneading the plurality of electrode materials in the multi-screw kneader; A method for manufacturing a battery, comprising:

[0057] Section 2: Item 2. The battery manufacturing method according to item 1, wherein the feeder is a circle feeder having blades and a drive device for rotating the blades.

[0058] Section 3: The feeder further includes a stirring member, Item 3. The method for manufacturing a battery according to item 2, wherein the supplying step includes stirring the plurality of materials placed in the supplying machine.

[0059] Section 4: Item 4. The method for manufacturing a battery according to item 3, wherein the stirring member is attached to the blade of the feeder.

[0060] Section 5: the plurality of electrode materials include a first electrode material and a second electrode material having a density greater than that of the first electrode material; Item 5. The method for manufacturing a battery according to any one of items 1 to 4, wherein in the step of placing in a container, a part of the second electrode material is placed in the container, and then the first electrode material is placed in the container, and further the remainder of the second electrode material is placed in the container. [Explanation of symbols]

[0061] 10. Slurry manufacturing equipment 20 Material supply device 21~23 Feeder 25 Index Table 27~29 Measuring device 30 Reversing machine 31 Container 32 Arm 33 Drive unit 40 Quantitative feeding machine (feeding machine) 41,42 Hopper 41a Inlet 41b,42a bottom 41b1,41c1 opening 41c intermediate plate 42a1 Outlet 43,44 Feathers 43a, 44a, 45a shaft 43b, 43c Feed blade 45 stirring member 45b Stirring plate 46 Drive unit 50 Twin-screw mixer 51 barrels 51a Powder supply port 51b Solvent supply port 51c Paste inlet 51d outlet 52 Shaft 52a screw 52b Paddle 53 Drive unit 55 Solvent supply device 56 Paste supply device A~C Electrode material

Claims

1. A step of measuring a plurality of electrode materials by a predetermined weight and placing the materials in a container; placing the plurality of electrode materials contained in the container into a feeder; supplying the plurality of electrode materials from the supply machine to a multi-shaft kneader; kneading the plurality of electrode materials in the multi-screw kneader; Including, The feeder is a circle feeder having a blade and a drive device that rotates the blade. How batteries are manufactured.

2. The feeder further includes a stirring member, The method of claim 1 , wherein the step of feeding includes agitating the materials placed in the feeder.

3. The method for manufacturing a battery according to claim 2 , wherein the stirring member is attached to the blade of the feeder.

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