JP2023080523A - Battery electrode manufacturing device and battery electrode manufacturing method - Google Patents

Abstract

To improve electron conductivity by forming a high-density electrode active material layer.SOLUTION: A battery electrode manufacturing device comprises: a powder supply unit for supplying a wet powder containing an electrode active material and an electrolyte to a bent-like substrate film; a conveyance unit for conveying the substrate film on which the wet powder supplied from the powder supply unit is mounted; a preliminary press unit including a pair of preliminary rollers for compressing the wet powder supplied from the powder supply unit to the substrate film; and a press unit including a pair of rollers for compressing the wet powder after the compression due to the preliminary press unit. The preliminary press unit includes a plurality of the pairs of preliminary rollers for compressing the wet powder step by step, and a gap between the pair of preliminary rollers is set larger than a gap between the pair of rollers.SELECTED DRAWING: Figure 3

Description

TECHNICAL FIELD The present invention relates to a battery electrode manufacturing apparatus and a battery electrode manufacturing method.

Lithium ion batteries are high-capacity secondary batteries and have been used in various applications in recent years. For example, an electrode of a lithium ion secondary battery has an active material layer on a current collector (see, for example, Patent Documents 1 and 2).

Patent Document 1 discloses a method for manufacturing a lithium polymer secondary battery using a lithium ion conductive gel as a solid electrolyte. In Patent Document 1, for example, a container holding an electrode (active material layer) impregnated with a precursor solution of a lithium ion conductive gel is flattened with a roller, and then the precursor solution is cured to form a flat surface on the electrode surface. It forms a lithium ion conductive gel layer.

In Patent Document 2, composite particles (granules) containing an active material and a binder are supplied as an electrode composition to a sheet-like current collector that is a strip-shaped base film, and the electrode composition is rolled by a roll press. Thus, an active material layer is formed. For example, in Patent Document 2, after the electrode composition is rolled once with a pair of rollers as a first rolling step, the electrode composition is multi-rolled with a plurality of pairs of rollers as a second rolling step to achieve a high density. active material layer.

Japanese Patent No. 4188668 Japanese Patent No. 6633866

In Patent Literature 2, the first rolling step is performed with large-diameter rollers, and the second rolling step is performed with small-diameter rollers. However, depending on the state of the electrode composition before compression, when a large-diameter roller is used in the first compression, the electrode composition may not be compacted in a flat state and may be compressed in an uneven state. . In such a case, a high-density active material layer cannot be formed, resulting in a decrease in electron conductivity.

The present invention has been made in view of the above circumstances, and provides a battery electrode manufacturing apparatus and a battery electrode manufacturing method capable of forming a high-density electrode active material layer to improve electron conductivity. intended to

In order to achieve the above object, the battery electrode manufacturing apparatus according to the present invention includes a powder supply unit that supplies wet powder containing an electrode active material and an electrolytic solution to a strip-shaped base film; and a pair of spare rollers for compressing the wet powder supplied from the powder supply unit onto the base film. A pre-press section and a press section including a pair of rollers for compressing the wet powder after compression by the pre-press section. The preliminary press section includes a plurality of the pair of preliminary rollers for compressing the wet powder in stages, and the gap between the pair of preliminary rollers is set larger than the gap between the pair of rollers.

ADVANTAGE OF THE INVENTION According to the battery electrode manufacturing apparatus and battery electrode manufacturing method of this invention, a high-density active material layer can be formed and electronic conductivity can be improved.

FIG. 1 is a schematic cross-sectional view of a single cell of a battery manufactured using the battery electrode manufacturing apparatus of the embodiment. FIG. 2 is a schematic diagram of the battery electrode manufacturing apparatus of the embodiment. FIG. 3 is a diagram showing a preliminary pressing device and a pressing device included in the battery electrode manufacturing apparatus of the embodiment. FIG. 4 is a diagram schematically showing the compression process of the electrode composition by the pre-pressing device and the pressing device. FIG. 5 is a diagram showing an example of a rotating mechanism included in the preliminary pressing device. FIG. 6 is a schematic diagram of a battery electrode manufacturing apparatus of a first modified example. FIG. 7 is a schematic diagram of a battery electrode manufacturing apparatus of a second modification.

(embodiment)
Embodiments to which the present invention is applied will be described below with reference to the drawings. In addition, in the drawings used in the following explanations, characteristic parts may be enlarged for the sake of convenience for the purpose of emphasizing the characteristic parts, and the dimensional ratios, etc. of each component may not necessarily be the same as the actual ones. do not have. Also, for the same purpose, some parts may be omitted from the drawings.

<Assembled battery (secondary battery)>
The battery electrode manufacturing apparatus and the battery electrode manufacturing method of the embodiments are applied, for example, to the manufacture of lithium ion batteries. Lithium ion batteries are assembled batteries that are modularized by combining a plurality of lithium ion single cells (also referred to as single cells or battery cells), or battery packs that are made by combining multiple such assembled batteries and adjusting the voltage and capacity. used in the form.

<Single cell (battery cell)>
FIG. 1 is a schematic cross-sectional view of a single cell 10. FIG. By combining a plurality of unit cells 10, the above assembled battery can be produced. For example, the single cell 10 has a positive electrode 20 a and a negative electrode 20 b as two electrodes 20 (battery electrodes) and a separator 30 .

The separator 30 is arranged between the positive electrode 20a and the negative electrode 20b. In the assembled battery, the plurality of unit cells 10 are stacked with the positive electrode 20a and the negative electrode 20b directed in the same direction.

The separator 30 holds an electrolyte. Thereby, the separator 30 functions as an electrolyte layer. The separator 30 is arranged between the electrode active material layers 22 of the positive electrode 20a and the negative electrode 20b to prevent them from coming into contact with each other. Thereby, the separator 30 functions as a partition wall between the positive electrode 20a and the negative electrode 20b.

The electrolyte held in the separator 30 includes, for example, an electrolytic solution or a gel polymer electrolyte. High lithium ion conductivity is ensured by using these electrolytes. Examples of the form of the separator include porous sheet separators and non-woven fabric separators made of polymers or fibers that absorb and retain the electrolyte.

The positive electrode 20 a and the negative electrode 20 b each have a current collector 21 , an electrode active material layer 22 and a frame 35 . The electrode active material layer 22 and the current collector 21 are arranged in this order from the separator 30 side. The frame 35 is frame-shaped (annular). The frame 35 surrounds the electrode active material layer 22 . The frame 35 of the positive electrode 20a and the frame 35 of the negative electrode 20b are welded together and integrated. In the following description, when distinguishing between the electrode active material layers 22 of the positive electrode 20a and the negative electrode 20b, they are referred to as a positive electrode active material layer 22a and a negative electrode active material layer 22b, respectively.

<Specific example of positive electrode current collector>
As the positive electrode current collector constituting the positive electrode current collector layer 21a, a known current collector used for a lithium ion single battery can be used. A resin current collector (such as the resin current collector described in JP-A-2012-150905 and WO 2015/005116) can be used. The positive electrode current collector constituting the positive electrode current collector layer 21a is preferably a resin current collector from the viewpoint of battery characteristics and the like.

Metal current collectors include, for example, copper, aluminum, titanium, nickel, tantalum, niobium, hafnium, zirconium, zinc, tungsten, bismuth, antimony, alloys containing one or more of these metals, and the group consisting of stainless alloys. and one or more metal materials selected from These metal materials may be used in the form of thin plates, metal foils, or the like. Alternatively, a metal current collector formed by forming the above metal material on the surface of a base material other than the above metal material by sputtering, electrodeposition, coating, or the like may be used.

The resin current collector preferably contains a conductive filler and a matrix resin. Examples of the matrix resin include polyethylene (PE), polypropylene (PP), polymethylpentene (PMP) and the like, but are not particularly limited. Also, the conductive filler is not particularly limited as long as it is selected from materials having conductivity. The conductive filler may be a conductive fiber having a fibrous shape.

The resin current collector may contain other components (dispersant, cross-linking accelerator, cross-linking agent, colorant, ultraviolet absorber, plasticizer, etc.) in addition to the matrix resin and the conductive filler. Also, a plurality of resin current collectors may be laminated and used, or a resin current collector and a metal foil may be laminated and used.

Although the thickness of the positive electrode current collector layer 21a is not particularly limited, it is preferably 5 to 150 μm. When a plurality of resin current collectors are laminated and used as the positive electrode current collector layer 21a, the total thickness after lamination is preferably 5 to 150 μm. The positive electrode current collector layer 21a can be obtained, for example, by molding a conductive resin composition obtained by melt-kneading a matrix resin, a conductive filler, and a dispersing agent for a filler used if necessary into a film by a known method. can be done.

<Specific example of positive electrode active material>
The positive electrode active material layer 22a is preferably a non-bound mixture containing a positive electrode active material. Here, the non-bound body means that the position of the positive electrode active material is not fixed in the positive electrode active material layer, and the positive electrode active materials and the positive electrode active material and the current collector are not irreversibly fixed. means When the positive electrode active material layer 22a is a non-bound body, the positive electrode active materials are not irreversibly fixed to each other. Even when stress is applied to the material layer 22a, the positive electrode active material moves, which is preferable because the destruction of the positive electrode active material layer 22a can be prevented. The positive electrode active material layer 22a, which is a non-binder, can be obtained by a method such as changing the positive electrode active material layer 22a into a positive electrode active material layer 22a containing a positive electrode active material and an electrolytic solution but not containing a binder. can. In this specification, the binder means an agent that cannot reversibly fix the positive electrode active materials together and the positive electrode active material and the current collector, and includes starch, polyvinylidene fluoride, polyvinyl alcohol, carboxyl Known solvent-drying type binders for lithium ion batteries such as methylcellulose, polyvinylpyrrolidone, tetrafluoroethylene, styrene-butadiene rubber, polyethylene and polypropylene can be used. These binders are used by dissolving or dispersing them in a solvent, and by volatilizing and distilling off the solvent, the surface solidifies without exhibiting adhesiveness, so that the positive electrode active material and the positive electrode active material and the current collector are solidified. cannot be reversibly fixed.

Examples of the positive electrode active material include, but are not particularly limited to, a composite oxide of lithium and a transition metal, a composite oxide containing two transition metal elements, and a composite oxide containing three or more metal elements. .

The positive electrode active material may be a coated positive electrode active material in which at least part of the surface is coated with a coating material containing a polymer compound. When the positive electrode active material is covered with the coating material, the volume change of the positive electrode is moderated, and the expansion of the positive electrode can be suppressed.

As the polymer compound constituting the coating material, those described as active material coating resins in JP-A-2017-054703 and WO 2015/005117 can be preferably used.

The coating material may contain a conductive agent. As the conductive agent, the same conductive filler as contained in the positive electrode current collector layer 21a can be preferably used.

The positive electrode active material layer 22a may contain an adhesive resin. As the adhesive resin, for example, a non-aqueous secondary battery active material coating resin described in JP-A-2017-054703 is mixed with a small amount of an organic solvent to adjust its glass transition temperature to room temperature or lower. Also, those described as adhesives in JP-A-10-255805 can be preferably used. In addition, adhesive resin is a resin that does not solidify even if the solvent component is volatilized and dried, and has adhesiveness (the property of adhering by applying a slight pressure without using water, solvent, heat, etc.) means On the other hand, a solution-drying type electrode binder used as a binder is one that dries and solidifies by volatilizing a solvent component, thereby firmly adhering and fixing active materials to each other. Therefore, the binder (solution-drying type electrode binder) and the adhesive resin described above are different materials.

The positive electrode active material layer 22a may contain an electrolytic solution containing an electrolyte and a non-aqueous solvent. As the electrolyte, those used in known electrolytic solutions can be used. As the non-aqueous solvent, those used in known electrolytic solutions (eg, phosphate esters, nitrile compounds, mixtures thereof, etc.) can be used. For example, a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) or a mixture of ethylene carbonate (EC) and propylene carbonate (PC) can be used.

The positive electrode active material layer 22a may contain a conductive aid. As the conductive aid, a conductive material similar to the conductive filler contained in the positive electrode current collector layer 21a can be preferably used.

Although the thickness of the positive electrode active material layer 22a is not particularly limited, it is preferably 150 to 600 μm, more preferably 200 to 450 μm, from the viewpoint of battery performance.

In the embodiment, the positive electrode composition supplied to form the positive electrode active material layer 22a is a wet powder containing a positive electrode active material and a non-aqueous electrolyte. Moreover, it is more preferable that the wet powder is in a pendular state or a funicular state.

The ratio of the non-aqueous electrolyte in the wet powder is not particularly limited, but in the case of the positive electrode, the ratio of the non-aqueous electrolyte to the entire wet powder is 0.5 to 0.5 to make the pendular state or funicular state. 15% by weight is desirable.

<Specific example of negative electrode current collector>
As the negative electrode current collector constituting the negative electrode current collector layer 21b, the same one as the positive electrode current collector can be appropriately selected and used, and can be obtained by the same method. The negative electrode current collector layer 21b is preferably a resin current collector from the viewpoint of battery characteristics and the like. Although the thickness of the negative electrode current collector layer 21b is not particularly limited, it is preferably 5 to 150 μm.

<Specific example of negative electrode active material>
The negative electrode active material layer 22b is preferably a non-bonded mixture containing a negative electrode active material. The reason why the negative electrode active material layer is preferably a non-binder, and the reason why the positive electrode active material layer 22a is preferably a non-binder , and the method for obtaining the positive electrode active material layer 22a which is a non-binder.

As the negative electrode active material, for example, a carbon-based material, a silicon-based material, a mixture thereof, or the like can be used, but the material is not particularly limited.

The negative electrode active material may be a coated negative electrode active material in which at least part of the surface is coated with a coating material containing a polymer compound. When the periphery of the negative electrode active material is covered with the coating material, the volume change of the negative electrode is moderated, and the expansion of the negative electrode can be suppressed.

As the coating material, the same coating material as that constituting the coated positive electrode active material can be suitably used.

The negative electrode active material layer 22b contains an electrolytic solution containing an electrolyte and a non-aqueous solvent. As for the composition of the electrolytic solution, an electrolytic solution similar to the electrolytic solution contained in the positive electrode active material layer 22a can be preferably used.

The negative electrode active material layer 22b may contain a conductive aid. As the conductive aid, a conductive material similar to the conductive filler contained in the positive electrode active material layer 22a can be preferably used.

The negative electrode active material layer 22b may contain an adhesive resin. As the adhesive resin, the same adhesive resin as an optional component of the positive electrode active material layer 22a can be preferably used.

Although the thickness of the negative electrode active material layer 22b is not particularly limited, it is preferably 150 to 600 μm, more preferably 200 to 450 μm, from the viewpoint of battery performance.

In the embodiment, the negative electrode composition supplied to form the negative electrode active material layer 22b is wet powder containing a negative electrode active material and a non-aqueous electrolyte. Moreover, it is more preferable that the wet powder is in a pendular state or a funicular state.

The ratio of the non-aqueous electrolyte in the wet powder is not particularly limited, but in the case of the negative electrode, the ratio of the non-aqueous electrolyte to the entire wet powder is 0.5 to 0.5 to make the pendular state or funicular state. 25% by weight is desirable.

<Specific example of separator>
Examples of the electrolyte held in the separator 30 include an electrolytic solution and a gel polymer electrolyte. By using these electrolytes, the separator 30 ensures high lithium ion conductivity. Examples of the form of the separator 30 include, but are not particularly limited to, polyethylene or polypropylene porous films.

<Specific example of frame>
The material for the frame 35 is not particularly limited as long as it is a material that is durable against the electrolytic solution. For example, a polymer material is preferable, and a thermosetting polymer material is more preferable. As a material for forming the frame 35, any material having insulating properties, sealing properties (liquid-tightness), heat resistance under the battery operating temperature, and the like may be used, and a resin material is preferably employed. More specifically, examples of the frame 35 include epoxy-based resins, polyolefin-based resins, polyurethane-based resins, and polyvinylidene fluoride resins. preferable.

<Battery Electrode Manufacturing Apparatus and Battery Electrode Manufacturing Method>
Next, a battery electrode manufacturing apparatus and a battery electrode manufacturing method (hereinafter abbreviated as a manufacturing method) of the present embodiment will be described. For example, in the battery electrode manufacturing apparatus and the battery electrode manufacturing method, the positive electrode 20a and the negative electrode 20b are first manufactured. The method of manufacturing the positive electrode 20 a and the method of manufacturing the negative electrode 20 b mainly differ in the electrode active material contained in the electrode active material layer 22 . Here, as a method for manufacturing the electrode 20, a method for manufacturing the positive electrode 20a and the negative electrode 20b will be collectively described.

FIG. 2 is a schematic diagram of the battery electrode manufacturing apparatus 1000. As shown in FIG. For example, the battery electrode manufacturing apparatus 1000 includes a chamber 100 , a transport mechanism 150 , a frame supply device 200 , a powder supply device 300 , a preliminary press device 400 and a press device 500 . The conveying mechanism 150 is an example of a conveying section, the powder supply device 300 is an example of a powder supply section, the preliminary pressing device 400 is an example of a preliminary pressing section, and the pressing device 500 is an example of a pressing section. An example. In addition, below, the case where the strip|belt-shaped base film is the strip|belt-shaped collector 21B is demonstrated as an example.

The chamber 100 is a room whose interior can be kept under a pressure lower than the atmospheric pressure. The pressure inside the chamber 100 is reduced below atmospheric pressure by a decompression pump (not shown). The standard atmospheric pressure is approximately 1013 hPa (approximately 10 ⁵ Pa).

For example, a current collector roll 21R is arranged outside the chamber 100, and a strip-shaped current collector 21B pulled out from the current collector roll 21R is transported into the chamber 100 through a slit. Hereinafter, the strip-shaped current collector 21B may be referred to as the current collector 21B. The current collector 21B is the current collector 21 before being cut into a predetermined shape. The current collector 21B is transported along the transport direction D. As shown in FIG. For example, the current collector 21B is transported at a predetermined speed by the transport mechanism 150 . Hereinafter, the direction in which the current collector 21B is conveyed will be described as the downstream side D1, and the opposite direction as the upstream side D2. The external space of the chamber 100 in which the current collector roll 21R is arranged may be at normal pressure, or may be decompressed by a chamber different from the chamber 100 .

The transport mechanism 150 shown in FIG. 2 has a driving roller and a driven roller. The drive roller is arranged above the current collector 21B, and rotates so that the current collector 21B is transported downstream D1 in the transport direction D under drive control by a control device (not shown). The driven roller is arranged below the current collector 21B, and rotates in conjunction with the movement of the current collector 21B to the downstream side D1 in the transport direction D by the rotation of the drive roller. A plurality of transport mechanisms 150 are installed spaced apart in the transport direction D in the internal space of the chamber 100 . The most upstream transport mechanism 150 sandwiches only the current collector 21B in the vertical direction and transports it to the downstream side D1 in the transport direction D. As shown in FIG. The transport mechanism 150 on the most downstream side sandwiches at least the current collector 21B and the frame 35 in the vertical direction and transports them to the downstream side D1 in the transport direction D. As shown in FIG.

The frame supply device 200 supplies the frame 35 to the conveyed current collector 21B. Although FIG. 2 shows the case where the frame supply device 200 is arranged inside the chamber 100 , the frame supply device 200 may be arranged outside the chamber 100 . For example, the frame supply device 200 has a robot arm, and places the pre-manufactured frame 35 at a predetermined position on the transported current collector 21B. After placing the frame 35 on the current collector 21B, the current collector 21B and the frame 35 may be compressed by a roll press so as to be sandwiched between them.

In addition, in FIG. 2, the prefabricated frame 35 is described as being placed on the current collector 21B, but the embodiment is not limited to this. For example, the frame 35 may be manufactured on the current collector 21B. As an example, the current collector 21B is used as a base material, and a predetermined material is discharged or applied in a predetermined shape onto the current collector 21B using a dispenser, a coater, or the like, thereby forming the frame 35 on the current collector 21B. can be formed.

The powder supply device 300 supplies the electrode composition 22c onto the current collector 21B transported within the chamber 100, as shown in FIG. As described above, in the embodiment, the electrode composition 22c (positive electrode composition , negative electrode composition) is a wet powder containing an electrode active material (positive electrode active material, negative electrode active material) and an electrolytic solution (non-aqueous electrolytic solution). That is, the powder supply device 300 supplies the wet powder containing the electrode active material and the electrolytic solution to the current collector 21B, which is a strip-shaped base film. Moreover, in the embodiment, it is more preferable that the wet powder as the electrode composition 22c is in a pendular state or a funicular state. Moreover, the electrode active material is a coated electrode active material coated with a coating material containing a polymer compound.

For example, the powder feeder 300 includes a hopper that holds the electrode composition 22c, which is wet powder, and a shutter that opens and closes the opening of the hopper. The powder supply device 300 can supply a desired amount of the electrode composition 22c to a desired position in the transport direction D on the transported current collector 21B by opening and closing the shutter. Since the electrode active material contained in the electrode composition 22c is a coated electrode active material, it is necessary to keep the electrode composition 22c in a soft state in the step of supplying it onto the current collector 21B. The transport mechanism 150 described above transports the current collector 21B on which the electrode composition 22c (wet powder) supplied from the powder supply device 300 is placed.

The preliminary pressing device 400 and the pressing device 500 compress the electrode composition 22c supplied onto the strip-shaped current collector 21B, which is an example of a strip-shaped base film, to form the electrode active material layer 22 shown in FIG. do. FIG. 3 is a diagram showing a preliminary press device 400 and a press device 500 included in the battery electrode manufacturing apparatus 1000. As shown in FIG. 4A and 4B are diagrams schematically showing the compression process of the electrode composition 22c by the preliminary press device 400 and the press device 500. FIG. 3 is an enlarged view of the preliminary press device 400 and the press device 500 shown in FIG. 2, with the frame 35 omitted.

The preliminary press device 400 includes a pair of preliminary rollers for compressing the wet powder (electrode composition 22c) supplied from the powder supply device 300 to the current collector 21B. Here, the preliminary pressing device 400 includes a plurality of pairs of preliminary rollers that compress the wet powder (electrode composition 22c) in stages. That is, the preliminary press device 400 includes at least two pairs of preliminary rollers. The preliminary pressing device 400 presses the electrode composition 22c, which is a wet powder containing an electrode active material and an electrolytic solution, placed on the current collector 21B onto a pair of preliminary rollers arranged along the conveying direction D. It is sandwiched together with the current collector 21B and compressed step by step. In the example shown in FIGS. 2 and 3, the preliminary press device 400 includes eight pairs of preliminary rollers: an upper preliminary roller 401a and a lower preliminary roller 402a, an upper preliminary roller 401b and a lower preliminary roller 402b, and an upper preliminary roller 401c. and a lower preliminary roller 402c, an upper preliminary roller 401d and a lower preliminary roller 402d, an upper preliminary roller 401e and a lower preliminary roller 402e, an upper preliminary roller 401f and a lower preliminary roller 402f, an upper preliminary roller 401g and a lower preliminary roller 402g. , an upper preliminary roller 401h and a lower preliminary roller 402h. In the following description, the upper spare rollers 401a to 401h and the lower spare rollers 402a to 402h are collectively referred to as "upper spare rollers 401" and "lower spare rollers 402" when they are not distinguished.

As shown in FIGS. 2 and 3, the upper preliminary roller 401 has the same diameter as the lower preliminary roller 402 with which it is paired. The lower preliminary rollers 402a to 402h contacting the current collector 21B from below are arranged at the same height. On the other hand, the upper preliminary rollers 401a to 401h that come into contact with the electrode composition 22c (wet powder) from above are arranged to gradually lower from the upstream side D2 toward the downstream side D1. In other words, the distance between the upper preliminary roller 401 and the lower preliminary roller 402 is gradually shortened from the upstream side D2 toward the downstream side D1. That is, the gap between the plurality of pairs of spare rollers decreases toward the downstream side D1 in the conveying direction D of the current collector 21B.

The electrode composition 22c is stepwise compressed from a thickness A to a thickness B1 by a preliminary pressing device 400, as shown in FIG. For example, the thickness A is 1000 μm and the thickness B1 is 700-800 μm. That is, the preliminary press device 400 reduces the thickness of the electrode composition 22c from 1000 μm to 700-800 μm in eight steps. For example, the pre-pressing device 400 reduces the thickness of the electrode composition 22c by 25-37.5 μm for each of eight roll-presses. The number of pairs of spare rollers (the upper spare roller 401 and the lower spare roller 402) is not limited to eight, and may be two or more. Preferably.

The pressing device 500 includes a pair of rollers that compress the electrode composition 22c (wet powder) after compression by the pre-pressing device 400 . The pressing device 500 compresses the electrode composition 22c (wet powder) with a pair of rollers having a larger diameter than the pair of preliminary rollers in the preliminary pressing device 400 . That is, the pressing device 500 sandwiches and compresses the electrode composition 22c compressed by the preliminary pressing device 400 together with the current collector 21B between a pair of rollers having a larger diameter than the pair of preliminary rollers. In the example shown in FIGS. 2 and 3, the press device 500 has an upper roller 501 and an upper roller 502 as a pair of rollers. As shown in FIGS. 2 and 3 , the upper roller 501 has the same diameter as the paired lower roller 502 , and the diameter of the upper roller 501 is larger than the diameter of the upper preliminary roller 401 . For example, the diameter of the upper preliminary roller 401 is ⅓ or less the diameter of the upper roller 501 . Also, the distance between the upper roller 501 and the lower roller 502 is shorter than the distance between the upper preliminary roller 401h and the lower preliminary roller 402h. In other words, the gap between the pair of spare rollers is set larger than the gap between the pair of rollers. The minimum gap among the gaps between the plurality of pairs of spare rollers is set larger than the gap between the pairs of rollers.

As shown in FIG. 3, the electrode composition 22c becomes the electrode active material layer 22 by being compressed from the thickness B1 to the thickness B2 by the pressing device 500. As shown in FIG. For example, the thickness B2 is 600 μm. That is, the press device 500 reduces the thickness of the electrode composition 22c from 700 to 800 μm to 600 μm in one roll press.

In the preliminary pressing step by the preliminary pressing device 400, the surface of the electrode composition 22c placed in a soft state is flattened by multistage roll pressing using small-diameter rollers (the upper preliminary roller 401 and the lower preliminary roller 402). While maintaining the state, it is gradually compressed little by little (see the left figure of FIG. 4). As a result, the gaps between the electrode active materials contained in the electrode composition 22c are gradually reduced, liquid bridges are formed, and they begin to stick to each other via the polymer compound, and are finally pressed to some extent. becomes. Then, in the pressing process by the pressing device 500, the electrode composition 22c in the compacted state is evenly distributed without being deformed by a single roll press using large-diameter rollers (upper roller 501 and lower roller 502). It is compressed to a desired thickness B2 to form an electrode active material layer 22 (see the right figure in FIG. 4). Note that the lower preliminary roller 402 and the lower roller 502 are omitted in FIG.

Here, the pair of preliminary rollers included in the preliminary pressing device 400 is rotationally driven according to the transport along the transport direction D of the current collector 21B, which is the base film. For this reason, the preliminary press device 400 preferably has a rotating mechanism 403 that rotates a plurality of pairs of preliminary rollers (the upper preliminary roller 401 and the lower preliminary roller 402) in conjunction with each other. FIG. 5 is a diagram showing an example of the rotating mechanism 403 included in the preliminary press device 400. As shown in FIG.

The rotation mechanism 403 shown in FIG. 5 transmits the rotation of the geared motor 403a to each of the upper preliminary rollers 401a to 401h rotatably held at a predetermined height by the holding member 403d via the pulley 403b and the timing belt 403c. do. A pulley 403b is provided on each of the rotating shafts of the geared motor 403a and the upper preliminary rollers 401a to 401h, and the timing belt 403c is stretched over two adjacent pulleys 403b. In this configuration, when the geared motor 403a rotates, the upper preliminary rollers 401a to 401h rotate together. The preliminary pressing device 400 has a rotating mechanism having the same configuration as the rotating mechanism 403 in order to rotate the lower preliminary rollers 402a to 402h in conjunction with each other. Here, the conveying speed along the conveying direction D of the current collector 21B, which is the base film, and the rotational speed of the pair of spare rollers are synchronized within a certain range so that the wet powder is uniformly compressed. ing. Such synchronous control is realized, for example, by controlling the rotation speed of the drive roller of the transport mechanism 150 and the rotation speed of the geared motor 403a.

After the preliminary pressing step and the pressing step, the electrode 20 (the current collector 21, the electrode active material layer 22, and the frame 35) is manufactured by appropriately cutting out the current collector layer 21 from the strip-shaped current collector 21B. be done. Also, the unit cell 10 is manufactured by laminating a pair of electrodes 20 (a positive electrode 20a and a negative electrode 20b) facing each other with a separator 30 interposed therebetween.

As described above, in the embodiment, by roll pressing using a plurality of pairs of small-diameter rollers (the upper preliminary roller 401 and the lower preliminary roller 402), the wet powder that is the electrode composition 22c is gradually compressed to deform. Preliminary pressing is performed until it becomes difficult to press. Thereafter, in the embodiment, the electrode composition 22c is compressed to a desired thickness by roll pressing using large-diameter rollers (upper roller 501 and lower roller 502). Accordingly, in the embodiment, the electron conductivity of the electrode 20 can be improved by forming the electrode active material layer 22 with a high density.

In addition, in the embodiment, the lines for the preliminary pressing process and the pressing process are lengthened by performing the multi-stage roll pressing by the preliminary pressing device 400, for example, with a small diameter roller having a diameter of ⅓ or less than the diameter of the large diameter roller. can be prevented.

Further, in the embodiment, by interlocking and rotating a plurality of pairs of preliminary rollers (upper preliminary roller 401 and lower preliminary roller 402), the electrode composition 22c can be reliably compressed little by little.

In addition, in the embodiment, the pre-pressing device 400 and the pressing device 500 are arranged in the chamber 100 whose inside pressure is reduced below atmospheric pressure. By compressing the wet powder, which is the electrode composition 22c, under reduced pressure, air can be prevented from remaining inside the electrode composition 22c, and the uniformity of the electrode active material layer 22 can be improved. In the embodiment, by performing multi-stage roll pressing with small-diameter rollers, it is possible to prevent the lines of the preliminary pressing process and the pressing process from becoming long. In the case of manufacturing electrodes in , it is also a great advantage from the viewpoint of capital investment.

Note that the electrode composition 22c tends to adhere to the roller, but in order to prevent this, the embodiment supplies the separator 30 on the electrode composition 22c and presses the electrode composition 22c through the preliminary press device 400 and the press device. 500 may be compressed. FIG. 6 is a schematic diagram of a battery electrode manufacturing apparatus 1000a of a first modified example.

In the battery electrode manufacturing apparatus 1000a shown in FIG. 6, the separator supply device 600 is arranged between the powder supply device 300 and the preliminary press device 400, and the separator recovery device 700 is arranged downstream D1 of the press device 500. be. The separator supply device 600 is an example of a separator supply section.

The separator supply device 600 supplies the separator 30 to the wet powder, which is the electrode composition 22c placed on the strip-shaped current collector 21B. For example, the separator supply device 600 is composed of a separator roll and a driving mechanism for pulling out the separator sheet 30B from the separator roll. The separator supply device 600 overlaps the electrode composition 22c conveyed along the conveying direction D at a predetermined speed while conveying the separator sheet 30B at the same predetermined speed. More specifically, the separator supply device 600 includes a roller as a driving mechanism positioned above the conveyed electrode composition 22c. By pressing, the separator 30 can be supplied to the electrode composition 22c.

A plurality of pairs of preliminary rollers (upper preliminary roller 401 and lower preliminary roller 402) and a pair of rollers (upper roller 501 and lower roller 502) spread the electrode composition 22c between the separator sheet 30B and the current collector 21. Sandwich and compress.

The separator recovery device 700 recovers the surplus portion of the separator sheet 30B. That is, the entire separator sheet 30B is not used as the separator 30, and there are cases where portions such as the ends of the separator sheet 30B are not cut out as the separator 30. FIG. The separator recovery device 600 recovers such surplus portions. When the separator supplying device 600 supplies the separator 30 to each electrode composition 22c, the battery electrode manufacturing device 1000a does not need to include the separator collecting device 700. FIG.

In the first modified example described above, the electrode composition 22c is compressed by the preliminary pressing device 400 and the pressing device 500 through the separator 30 (separator sheet 30B), so that the electrode composition 22c is applied to the upper preliminary roller 401 and the upper roller 501. Adhesion of the composition 22c can be prevented. As a result, in the first modification, the surface of the electrode active material layer 22 formed by compressing the electrode composition 22c becomes uneven, and the amount of the electrode composition 22c contained in the electrode 20 becomes unstable. can definitely be avoided.

In addition, from the viewpoint of preventing the electrode composition 22c from adhering to the roller, the embodiment supplies a release film on the electrode composition 22c, and presses the electrode composition 22c by the preliminary press device 400 and the press device 500. You can compress it. FIG. 7 is a schematic diagram of a battery electrode manufacturing apparatus 1000b of a second modification.

In the battery electrode manufacturing apparatus 1000b shown in FIG. 900 is placed. The release film supply device 800 is an example of a release film supply unit.

The release film supply device 800 supplies the release film 40B to the electrode composition 22c placed on the current collector 21B. Although the material of the release film 40B is not particularly limited, PET (Polyethylene terephthalate) can be used as an example. Also, a release agent may be applied to the surface of the release film 40B. For example, the release film supply device 400 includes a release film roll obtained by winding a belt-shaped release film 40B into a roll, and a drive mechanism for pulling out the release film from the release film roll. The release film supply device 400 superimposes the release film 40B on the electrode composition 22c transported at a predetermined speed along the transport direction D while transporting the release film 40B at the same predetermined speed. More specifically, the release film supply device 400 includes a roller as a driving mechanism positioned above the transported electrode composition 22c. By pressing against the object 22c, the release film 40B can be supplied to the electrode composition 22c.

Then, a plurality of pairs of preliminary rollers (upper preliminary roller 401 and lower preliminary roller 402) and pairs of rollers (upper roller 501 and lower roller 502) transfer the electrode composition 22c to the release film 40B and the current collector 21. sandwiched between and compressed.

The release film recovery device 600 separates and recovers the release film 40B compressed by the preliminary press device 400 and the press device 500 from the electrode active material layer 22 . For example, the release film recovery device 600 winds up the release film 40B after being compressed by the press device 500, and manages the release film 40B in a roll form that is easy to discard or reuse.

In the second modified example described above, the electrode composition 22c is compressed by the preliminary pressing device 400 and the pressing device 500 through the release film 40B, so that the electrode composition 22c is applied to the upper preliminary roller 401 and the upper roller 501. adhesion can be prevented. As a result, even in the second modification, the surface of the electrode active material layer 22 formed by compressing the electrode composition 22c becomes uneven, and the amount of the electrode composition 22c contained in the electrode 20 becomes unstable. can definitely be avoided.

In the above-described embodiment, the first modified example, and the second modified example, the case where the electrode composition 22c placed in the frame 35 is compressed by the pre-pressing device 400 and the pressing device 500 has been described. It is not limited to this. For example, the electrode composition 22c is continuously placed on the strip-shaped current collector 21B and compressed by the preliminary pressing device 400 and the pressing device 500 to form a strip-shaped electrode active material layer, and then the frame A strip-shaped electrode active material layer may be trimmed into a rectangular electrode active material layer 22 so that 35 can be arranged. Alternatively, a mask or the like having a space in which the electrode active material layer 22 can be formed is placed on the strip-shaped current collector 21B, and the electrode composition 22c is supplied to the inside thereof. may compress the electrode composition 22c. In such a case, the frame 35 is placed after the mask is removed.

Further, in the embodiment, the first modification, and the second modification described above, the strip-shaped base film on which the electrode composition 22c is placed is the strip-shaped current collector 21B. not to be For example, instead of the strip-shaped current collector 21B shown in FIG. 2, a strip-shaped separator sheet 30B or a strip-shaped release film 40B may be used as the base film.

As described above, the embodiment of the present invention has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment. is also included. Furthermore, it goes without saying that the configurations shown in the respective embodiments can be used in combination as appropriate.

10: Single cell 20: Electrode 20a: Positive electrode 20b: Negative electrode 21: Current collector 21a: Positive electrode current collector layer 21b: Negative electrode current collector layer 21B: Strip-shaped current collector 21R: Current collector roll 22: Electrode active material Layer 22a: Positive electrode active material layer 22b: Negative electrode active material layer 22c: Electrode composition (wet powder)
30: Separator 30B: Separator sheet 35: Frame 40B: Release film 100: Chamber 150: Conveying mechanism 200: Frame supply device 300: Powder supply device 400 Preliminary press device 401, 401a, 401b, 401c, 401d, 401e , 401f, 401g, 401h: upper spare rollers 402, 402a, 402b, 402c, 402d, 402e, 402f, 402g, 402h: lower spare rollers 403: rotating mechanism 403a: geared motor 403b: pulley 403c: timing belt 403d: holding member,
500: Press device 501: Upper roller 502: Lower roller 600: Separator supply device 700: Separator recovery device 800: Release film supply device 900: Release film recovery device 1000, 1000a, 1000b: Battery electrode manufacturing device D: Conveyance Direction D1: Downstream D2: Upstream

Claims (9)

A powder supply unit that supplies wet powder containing an electrode active material and an electrolytic solution to a strip-shaped base film;
a conveying unit that conveys the base film on which the wet powder supplied from the powder supply unit is placed;
a preliminary press section including a pair of preliminary rollers for compressing the wet powder supplied from the powder supply section to the base film;
a press section including a pair of rollers for compressing the wet powder after compression by the preliminary press section;
with
The preliminary press unit includes a plurality of the pair of preliminary rollers for compressing the wet powder in stages,
The battery electrode manufacturing apparatus, wherein the gap between the pair of spare rollers is set larger than the gap between the pair of rollers. The preliminary press section includes at least two of the pair of preliminary rollers,
the gap between the plurality of pairs of spare rollers decreases in the conveying direction of the base film,
A minimum gap among the gaps between the plurality of pairs of spare rollers is set larger than the gap between the pair of rollers,
The battery electrode manufacturing apparatus according to claim 1. The press section compresses the wet powder with the pair of rollers having a larger diameter than the pair of preliminary rollers in the preliminary press section.
The battery electrode manufacturing apparatus according to claim 1 or 2. The pair of preliminary rollers are rotationally driven according to the transport along the transport direction of the base film,
The preliminary press unit has a rotation mechanism that rotates the plurality of pairs of preliminary rollers in conjunction with each other,
The battery electrode manufacturing apparatus according to any one of claims 1 to 3. The conveying speed along the conveying direction of the base film and the rotational speed of the pair of preliminary rollers are synchronized within a certain range,
The battery electrode manufacturing apparatus according to any one of claims 1 to 4. A separator supply unit that supplies a separator to the wet powder,
further comprising
The plurality of pairs of preliminary rollers and pairs of rollers pinch and compress the wet powder between the separator and the base film.
The battery electrode manufacturing apparatus according to any one of claims 1 to 5. The preliminary press section and the press section are arranged in a chamber whose interior is evacuated below atmospheric pressure,
The battery electrode manufacturing apparatus according to any one of claims 1 to 6. The wet powder is a pendular or funicular wet powder,
The battery electrode manufacturing apparatus according to any one of claims 1 to 7. A supply step of supplying a wet powder containing an electrode active material and an electrolytic solution to a strip-shaped base film;
A supply step of conveying the base film on which the wet powder supplied by the supply step is placed;
A preliminary pressing step of compressing the wet powder supplied to the base film by the supplying step with a pair of preliminary rollers;
A pressing step of compressing the wet powder with a pair of rollers after compression by the preliminary pressing step;
including
The preliminary pressing step includes stepwise compression of the wet powder by a plurality of pairs of preliminary rollers,
The method for manufacturing a battery electrode, wherein the gap between the pair of spare rollers is set larger than the gap between the pair of rollers.

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