A device for manufacturing an electrode for a battery, comprising an extruder having a current collector device

Abstract

The subject of the present invention is a device (1) for manufacturing an electrode strip (9) for a battery, the electrode strip (9) comprising a current collector strip (5) and at least one layer of an electrochemically active composite material (6) on either side of the current collector strip. The device (1) comprises an extruder (2), which in turn comprises a sheath (20), an extrusion head (23), and an extrusion screw (3). According to the present invention, the extrusion screw (3) comprises an outer tube (32) and an inner tube (31) that are coaxial and mounted within each other. The outer tube (31) is mounted so that it can rotate and move relative to the sheath (20). The inner tube (32) is stationary relative to the sheath (20) and has an outlet (330) located upstream of the extrusion head (23). Furthermore, the manufacturing device (1) comprises advancing and unwinding means (4, 41, 42) configured to transport the current collector strip (5) through the inner tube (32) to the extrusion head (23).

Description

Technical Field

[0001] The present invention relates to the field of electric batteries composed of a negative electrode and a positive electrode.

[0002] More specifically, the present invention relates to a device for manufacturing electrodes for batteries.

Background Art

[0003] Specifically, in the field of electric batteries such as lithium batteries, electrodes in the form of thin plates are known that comprise at least one layer of an electrochemically active composite material adhered onto a current collector device. The current collector device is generally formed of a thin layer of metal, such as a layer of aluminum for the positive electrode.

[0004] WO2004 / 051769A2 discloses a method for forming battery electrodes using an extrusion device. Specifically, this extrusion device comprises a co-extrusion station with two extruders and a rolling station. The co-extrusion station forms an assembly that combines a layer of electroactive composite material and a layer of electrolyte. The assembly leaving the co-extrusion station is then rolled on the current collector device within the rolling station to form an electrode unit.

[0005] The rolling station comprises two counter-rotating cylindrical rollers that apply pressure to assemble the assembly leaving the co-extrusion station and the current collector device. To ensure uniform flatness, a tension roller for maintaining the tension applied to the current collector device strip is mounted below the rolling station.

[0006] However, the structure of the above-described extrusion device is complex. The structure of this extrusion device requires two extruders and even a rolling station. Therefore, the installation and use costs of this device are high.

[0007] Furthermore, considering that the electrode is assembled by rolling two solid elements, it is difficult to control the subsequent adhesion of the electrode.

[0008] In view of the problems mentioned above, one object of the present invention is to simplify the device for manufacturing the electrode, and thus reduce the cost of installing and manufacturing the above device. Furthermore, another object of the present invention is to ensure that the various layers of the electrode are firmly adhered to each other.

Summary of the Invention

[0009] With this object in mind, the present invention proposes a device for manufacturing an electrode strip for a battery, the electrode strip comprising at least one layer of a composite material that is electrochemically active on either side of a current collector strip, and this manufacturing device comprises - an extruder, - a sheath defining the boundary of the mixing chamber, - an extrusion head for shaping the electrode strip as it exits the extruder, and - an extrusion screw disposed within the mixing chamber comprising an extruder is provided.

[0010] According to the present invention, the extrusion screw comprises - an outer tube installed to rotate within the mixing chamber, the outer tube comprising drive means configured to mix the active composite material within the mixing chamber and move the material downstream towards the extrusion head, an outer tube, and - an inner tube disposed at least partially inside the outer tube and coaxial with the outer tube, the inner tube being stationary relative to the sheath and having an outlet located upstream of the extrusion head, an inner tube, and is provided.

[0011] Furthermore, according to the present invention, the manufacturing device comprises advancing and feeding means configured to convey the current collector strip through the inner tube to the extrusion head.

[0012] Thus, the deposition of the layer of the composite material electrochemically active with respect to the current collector is carried out inside the extruder. Due to the fact that the composite material electrochemically active is in liquid form inside the extruder, the layer of the composite material adheres perfectly to the current collector strip and is uniformly distributed on said strip. Thereby, the quality of the adhesion between the layers is improved.

[0013] Furthermore, the structure of the proposed device is simplified. The reason is that the structure of the proposed device comprises a single extruder. Although the extruder is constructed with two different tubes, the extruder is arranged such that one extruder is placed inside the other extruder, thereby forming a compact arrangement that enables the extrusion screw to occupy the same volume as the extrusion screw of a conventional extruder in the mixing chamber.

[0014] According to another feature of the present invention, - the inner tube and the advancing and feeding means are arranged relative to each other so as to arrange the current collector strip in a floating state inside the inner tube, - the sheath has a rotating body shape, the rotation axis of the sheath coincides with the main axis of the extrusion screw, and the main axis of the extrusion screw is in the plane passing through the current collector strip, - the inner tube has an end head formed by a smooth wall located outside the outer tube, - according to the above point, the end head comprises a hemispherical portion, and the outlet is arranged at the tip of the hemispherical portion, - the manufacturing device comprises a sealing member arranged between the end head and the outer tube, - according to the above point, the end head comprises a cylindrical skirt facing the annular portion of the outer tube, and the sealing means is sandwiched between the cylindrical skirt and the above portion of the outer tube, - The manufacturing device comprises means for applying tension to the current collector strip. - The manufacturing device comprises heating means arranged around the extruder. - The manufacturing device comprises electrode drying means arranged downstream of the extruder.

[0015] Other features and advantages of the present invention will become apparent by reading the following detailed description while referring to the accompanying drawings, which can be understood.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0017] FIGS. 1 and 2 show an electrode manufacturing device 1, hereinafter referred to as device 1, which has the function of forming a continuous electrode strip 9 composed of two layers of a composite material 6 that is electrochemically active and is arranged on either side of the current collector strip 5 and the current collector strip 5.

[0018] In the illustrated embodiment, device 1 comprises an extruder 2 into which a composite material that is electrochemically active in liquid or powder form is introduced. In this case, the "composite material that is electrochemically active" is one or more composite materials that are electrochemically active (by way of example: LiNi x Mn y COz It means a mixture of materials including an active material such as O2 or graphite, one or more electronically conductive additives (e.g., carbon black), and one or more polymer binders (e.g., polyvinylidene fluoride). In the case of all-solid-state batteries, the mixture can include one or more ion-conductive materials of the polymer type and / or ceramic type (e.g., poly(ethylene oxide) + LiTFSI).

[0019] The composite material that is electrochemically active, after being placed in the extruder, is mixed and pushed from upstream to downstream in the extrusion direction indicated by arrow F in Figure 1. In the remainder of this description, the composite material that is electrochemically active is referred to as the composite.

[0020] In this embodiment, the extruder 2 includes a cylindrical sheath 20 fixed around the rotation axis L and a frustoconical extrusion head 23 formed as a single piece with the sheath 20. The sheath 20 defines the boundary of the mixing chamber 21 and is oriented such that the rotation axis L of the sheath 20 is parallel to the extrusion direction F. The extrusion head 23 includes a die 230, and the die 230 gives the electrode strip 9 a rectangular cross-section. Of course, the die 230 may be designed in different forms to give other shapes to the electrode strip 9.

[0021] The extruder 2 has a supply hopper 22 communicating with the mixing chamber 21, and the composite for supplying the extruder 2 is injected into the mixing chamber 21. In addition, the extruder 2 includes an extrusion screw 3 disposed in the mixing chamber 21, and as a result, the main axis I of the extrusion screw 3 coincides with the rotation axis L of the sheath 20.

[0022] According to the present invention, as in this embodiment, the extrusion screw 3 includes an outer tube 31 installed to rotate within the mixing chamber 21. The outer tube 31 includes a cylindrical trunk 310 and blades 311 spirally arranged around the cylindrical trunk 310. When the outer tube 31 rotates, the blades 311 move, mixing the composite material and advancing the mixed material longitudinally downstream in the extrusion direction F. The rotation of the outer tube 31 is controlled by a motor not shown in the figure.

[0023] In other words, the blades 311 and the motor constitute driving means for mixing the composite material and for moving the said material towards the extrusion head 23.

[0024] The extrusion screw 3 further includes an inner tube 32 having a diameter smaller than that of the outer tube 31 and a length greater than that of the outer tube 31. Thus, the inner tube 32 designed in this way will be partially disposed inside the outer tube 31 and will be coaxially arranged with the said outer tube 31.

[0025] Specifically, the inner tube 32 is composed of a cylindrical portion 320 and an end head 33. The cylindrical portion 320 having a length substantially equal to the length of the outer tube 31 is located inside the outer tube 31. Regarding the end head 33, the end head 33 is located outside the outer tube 31. In other words, the end head 33 is located subsequent to the mixing section where the outer tube 31 and its blades 311 are located.

[0026] As shown in FIGS. 1, 2, and 4, the end head 33 includes a cylindrical portion 333, and a hemispherical portion 331 is located subsequent to the cylindrical portion 333. When viewed from the side, the end head 33 of this embodiment has a bullet shape.

[0027] A through slot 330 is made in the tip portion 331. The through slot 330 is oriented in the transverse direction T perpendicular to the extrusion direction F. The extrusion direction F and the transverse direction T are in a horizontal plane.

[0028] Furthermore, the inner tube 32 is stationary with respect to the sheath 20 and thus does not follow the rotational movement of the outer tube 31. In this case, a ball bearing 34 is arranged between the two tubes, thereby allowing the two tubes to move independently.

[0029] During the operation of the extruder 2, there is a risk that the composite material moved by the outer tube 31 and by the driving means of the outer tube 31 reaches the space between the outer tube 31 and the inner tube 32. To prevent such ingress, a sealing member is arranged between the two tubes.

[0030] In this case, the sealing member 35 is arranged on the end head 33. Specifically, as can be seen in FIG. 4, the end head 33 comprises a cylindrical skirt 332 oriented parallel to the extrusion direction F.

[0031] The cylindrical skirt 332 faces the annular portion 312 of the outer tube 31. The sealing member 35 is inserted between the cylindrical skirt 332 and the annular portion 312. In this case, the sealing member 35 may be a lip seal or a sealed ball bearing that allows both the rotation of the outer tube 31 and the immobility of the inner tube 32 to be observed.

[0032] According to the present invention, as in the illustrated embodiment, the device 1 further comprises advancing and feeding means configured to convey the current collecting device strip 5 in the extrusion direction F through the inner tube 32 to the extrusion head 23. The current collecting device strip 5 leaves the extruder 2 through the die 230.

[0033] In this case, the advancing and feeding means comprises two pairs 4 of rotating rollers arranged upstream and downstream of the extruder 2 respectively. Each of the pairs 4 consists of a lower roller 41 for feeding and an upper roller 42 for advancing.

[0034] Two pairs 4 of rotating rollers are positioned at equal height, thereby ensuring that the current collector strip 5 is parallel to the extrusion direction F.

[0035] Furthermore, the pairs 4 of rotating rollers are positioned relative to the extruder 2 such that when the current collector strip 5 enters the inner tube 32, this strip is in a floating state as a result, i.e., the strip is not in contact with the wall of the inner tube 32. In addition to the positioning of the pairs 4 of rotating rollers relative to the extruder 2, the current collector strip 5 can be dimensioned such that its width is less than the diameter of the inner tube 32 in order to facilitate the floating of the strip 5. By doing so, friction between the current collector strip 5 and the interior of the inner tube 32 is avoided.

[0036] The floating state of the current collector strip 5 within the inner tube can be seen in FIGS. 3A and 3B.

[0037] In FIG. 3C, it can be seen that the current collector strip 5 leaves the inner tube 32 through the through slot 330, and the cross-section of the through slot 330 is slightly larger than the cross-section of the strip, thereby preventing any contact between the slot 330 and the strip 5. The through slot 330 constitutes the outlet of the inner tube 32. Furthermore, the arrangement between the pairs 4 of rotating rollers and the extruder 2 can be made such that the current collector strip 5 is placed within the symmetry plane of the extruder 2. In this case, the symmetry plane of the extruder 2 is a horizontal plane passing through the rotation axis L of the sheath 20 and thus the main axis I of the screw 3. The reason is that these two axes coincide. Due to the current collector strip 5 being positioned within the symmetry plane, the current collector strip 5 is covered on both sides by an equal amount of composite material when leaving the inner tube 32. This ensures a balanced pressure distribution on each side of the current collector strip 5, thereby making it possible to prevent the sliding device strip from twisting or becoming coiled.

[0038] Furthermore, the geometry of the end head 33 also helps to prevent deformation of the current collector strip 5 during the adhesion of the composite material on the current collector strip 5. Specifically, as described above, the end head 33 is formed of a smooth wall. This makes it possible to reduce the rotational movement of the composite material when the composite material contacts the end head, and as a result, the composite material is advanced by translational movement.

[0039] Furthermore, due to the circular shape of the hemispherical portion 331, the composite material is guided little by little towards the outlet 330, and the current collector strip 5 emerges from the outlet 330. Therefore, the adhesion of the composite material on the current collector strip is carried out in a fluid and precisely adjusted manner.

[0040] At the outlet of the extruder 2, a double-coated electrode strip is obtained, which is composed of the current collector strip 5 and two layers of the composite material 6 located on either side of the current collector strip.

[0041] Optionally, a heating device 7 can be arranged around the sheath 20 to promote the mixing of the composite material in the mixing chamber.

[0042] The device 1 further comprises a drying means 8 arranged downstream of the extruder 2 for fixing the layer of the composite material 6 on the current collector strip 5. The drying means 8 can use low-temperature air or high-temperature air depending on the properties of the composite material.

[0043] A rolling station 43 is located after the drying means 8. The rolling station 43 comprises two counter-rotating rollers, and the dried electrode strip passes between the two counter-rotating rollers.

[0044] After this rolling step, the electrode strip 9 is wound around a mandrel, thereby forming an electrode coil ready for power storage. Alternatively, the double-coated electrode strip is cut to produce individual electrodes.

[0045] The electrodes formed from the electrode strip 9 enable reducing the number of current collectors within the battery, and thus enable reducing the size of the battery. Accordingly, a smaller-sized battery also addresses the constraints associated with increased restrictions on the space available within the engine compartment.

Claims

1. A device (1) for manufacturing an electrode strip (9) for a battery, wherein the electrode strip (9) comprises at least one layer of a composite material (6) that is electrochemically active and a current collector strip (5), and the device (1) comprises An extruder (2), A sheath (20) defining the boundary of a mixing chamber (21), An extrusion head (23) for shaping the electrode strip (9) as it exits the extruder, and An extrusion screw (3) disposed within the mixing chamber (21) The extruder (2) comprising In the device (1) comprising The extrusion screw (3) is An outer tube (31) installed to rotate within the mixing chamber (21), the outer tube (31) comprising drive means (310, 311) configured to mix the active composite material within the mixing chamber (21) and to move the composite material downstream towards the extrusion head (23); and An inner tube (32) disposed at least partially within the outer tube (31) and coaxial with the outer tube (31), the inner tube (32) being stationary relative to the sheath (20) and having an outlet (330) located upstream of the extrusion head (23); and Comprising The device (1) comprises forward / feeding means (4, 41, 42) configured to convey the current collector strip (5) through the inner tube (32) to the extrusion head (23) The device (1) being characterized in that.

2. The extruder (2) and the advancing / feeding means (4, 41, 42) are arranged relative to each other such that the current collector strip (5) is arranged in a floating state inside the inner tube (32), the device (1) according to claim 1, characterized in that.

3. The sheath (20) has a rotating body shape, and the rotation axis (L) of the sheath (20) coincides with the main axis (l) of the extrusion screw (3), The main axis (l) is in a plane passing through the current collector strip (5) The device (1) according to claim 1 or claim 2, characterized in that.

4. The inner tube (32) is located outside the outer tube (31) and has an end head (33) formed by a smooth wall, the device (1) according to any one of claims 1 to 3, characterized in that.

5. The end head (33) includes a hemispherical portion (331), and the outlet (330) is arranged at the tip of the hemispherical portion (331), the device (1) according to claim 4, characterized in that.

6. The device (1) according to claim 4 or claim 5, characterized in that it includes a sealing member (35) arranged between the end head (33) and the outer tube (31).

7. The end head (33) includes a cylindrical skirt (332) facing the annular portion (312) of the outer tube (31), and the sealing member (35) is inserted between the cylindrical skirt (332) and the annular portion (312) of the outer tube, the device (1) according to claim 6, characterized in that.

8. The device (1) according to any one of claims 1 to 7, characterized in that it includes heating means (7) arranged around the extruder (2).

9. The device according to any one of claims 1 to 8, characterized in that it comprises drying means (8) arranged downstream of said extruder (2).

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