Apparatus for manufacturing battery electrodes including an extruder with a current collector

Abstract

The subject of this invention is an apparatus (1) for manufacturing an electrode strip (9) for a battery, the electrode strip comprising a current collector strip (5) and at least one layer of electrochemically active composite material (6) on either side of the current collector strip. The apparatus (1) includes an extruder (2) comprising a sheath (20), an extrusion head (23), and an extrusion screw (3). According to the invention, the extrusion screw (3) comprises an outer tube (31) and an inner tube (32) coaxially mounted to each other. The outer tube (31) is mounted to be rotatably movable relative to the sheath (20). The inner tube (32) is stationary relative to the sheath (20) and includes an outlet (330) located upstream of the extrusion head (23). Furthermore, the manufacturing apparatus (1) includes advance and unwind devices (4, 41, 42) configured to convey the current collector strip (5) through the inner tube (32) to the extrusion head (23).

Description

Technical Field

[0001] This invention relates to the field of batteries consisting of a negative electrode and a positive electrode.

[0002] More specifically, this invention relates to an apparatus for manufacturing electrodes for batteries. Background Technology

[0003] In the field of batteries (especially lithium batteries), electrodes in the form of thin plates are known to include at least one layer of electrochemically active composite material deposited on a current collector. The current collector is typically formed from a thin metal layer (e.g., an aluminum layer for the positive electrode).

[0004] WO 2004 / 051769 A2 discloses a method for forming battery electrodes using an extrusion apparatus. Specifically, this extrusion apparatus includes a co-extrusion station having two extruders and a rolling station. The co-extrusion station forms an assembly combining an electroactive composite material layer and an electrolyte layer. The assembly exiting the co-extrusion station is then rolled on a current collector in the rolling station to form an electrode unit.

[0005] The rolling station includes two counter-rotating cylindrical rollers that apply pressure to assemble the components leaving the co-extrusion station and the current collector. To ensure uniform flatness, tension rollers are installed downstream of the rolling station to maintain tension on the current collector belt.

[0006] However, the structure of the aforementioned extrusion equipment is complex. It requires two extruders and a rolling station. Therefore, the cost of installing and using this equipment is high.

[0007] Furthermore, given that the electrodes are assembled by rolling two solid elements, it is difficult to control the subsequent adhesion of these two solid elements.

[0008] In view of the above problems, one object of the present invention is to simplify the equipment used for manufacturing electrodes and thus reduce the cost of installing and maintaining said equipment. Furthermore, another object of the present invention is to ensure that the various layers of the electrode adhere firmly to each other. Summary of the Invention

[0009] With this objective in mind, the present invention provides an apparatus for manufacturing an electrode strip for a battery, the electrode strip comprising at least one layer of electrochemically active composite material on either side of a current collector strip, the manufacturing apparatus comprising:

[0010] - An extruder, comprising:

[0011] -Sheath, which defines the mixing chamber.

[0012] - An extruder that delivers the electrode strip, thereby allowing the extruder to maintain the shape of the electrode strip; and

[0013] - An extrusion screw, which is arranged in the mixing chamber.

[0014] According to the present invention, the extrusion screw comprises:

[0015] - An outer tube, which is mounted such that it rotates on its own in the mixing chamber, the outer tube including a drive device configured to mix the active composite material in the mixing chamber and move the material downstream toward the extruder;

[0016] - An inner tube, which is at least partially disposed inside the outer tube and coaxially disposed with the outer tube, the inner tube being stationary relative to the sheath and including an outlet located upstream of the extruder head.

[0017] Furthermore, according to the invention, the manufacturing apparatus includes a feeding and unwinding device configured to convey the current collector belt through the inner tube to the extrusion head.

[0018] Therefore, the deposition of this electrochemically active composite material layer on the current collector is carried out inside the extruder. Because the electrochemically active composite material layer is in liquid form in the extruder, it adheres completely to the current collector belt and is uniformly distributed on the belt. This improves the adhesion quality between the layers.

[0019] Furthermore, the structure of the proposed device is simplified because it comprises a single extruder. Although the extruder consists of two distinct tubes, these tubes are arranged so that one is inside the other to form a compact arrangement, allowing the extrusion screw to occupy the same volume in the mixing chamber as the extrusion screw of a conventional extruder.

[0020] Other features according to the invention:

[0021] - The inner tube and the propulsion and unwinding device are arranged relative to each other in such a way that the current collector is suspended inside the inner tube;

[0022] - The sheath has a rotary shape, the axis of rotation of which coincides with the main axis of the extrusion screw; and the main axis of the extrusion screw lies in a plane passing through the current collector.

[0023] - The inner tube includes an end located outside the outer tube and formed by a smooth wall;

[0024] -According to the previous point, the end includes a hemispherical portion, and the outlet is located at the tip of the hemispherical portion;

[0025] -The manufacturing equipment includes a sealing component disposed between the end and the outer tube;

[0026] -According to the previous point, the end includes a cylindrical skirt facing the annular portion of the outer tube; and a sealing device is sandwiched between the cylindrical skirt and the portion of the outer tube;

[0027] - The manufacturing equipment includes a device for tensioning the current collector belt;

[0028] - The manufacturing equipment includes a heating device arranged around the extruder;

[0029] - The manufacturing equipment includes an electrode drying unit located downstream of the extruder. Attached Figure Description

[0030] Further features and advantages of the invention will become apparent from the following detailed description, which will be understood with reference to the accompanying drawings, in which:

[0031] Figure 1 This is a schematic diagram showing a longitudinal cross-section through an electrode manufacturing apparatus according to an embodiment of the present invention;

[0032] Figure 2 is with Figure 1 The same view, and shows the formation in more detail. Figure 1 The extruder and drying unit are part of the electrode manufacturing equipment;

[0033] Figure 3 Includes three illustrations Figure 3 A through 3C respectively show the... Figure 1 Passing through the three planes AA, BB and CC shown Figure 1 The cross-section of the electrode manufacturing equipment;

[0034] Figure 4 This is a schematic diagram showing the process of forming Figure 1 The longitudinal section of an extrusion screw, which is part of the electrode manufacturing equipment. Detailed Implementation

[0035] Figure 1 and Figure 2 An electrode manufacturing apparatus 1 (hereinafter referred to as apparatus 1) is shown, which has the function of forming a continuous electrode strip 9, which is composed of a current collector strip 5 and two layers of electrochemically active composite material 6 arranged on either side of the current collector strip 5.

[0036] In the example shown, device 1 includes an extruder 2 into which the electrochemically active composite material, in liquid or powder form, is introduced. In this context, "electrochemically active composite material" means a mixture of materials comprising: one or more electrochemically active materials (e.g., LiNi). x Mn y Coz The mixture may include active materials 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 may include one or more ion-conducting materials of polymer and / or ceramic types (e.g., poly(ethylene oxide) + LiTFSI).

[0037] Electrochemically active composite materials are mixed and flow along the extruder once placed in the extruder. Figure 1 The extrusion direction indicated by arrow F is from upstream to downstream. In the remainder of the description, the electrochemically active composite material will be referred to as a composite material.

[0038] In this example, the extruder 2 includes a cylindrical sheath 20 fixed around a rotation axis L and a truncated conical extrusion head 23 formed in one piece with the sheath 20. The sheath 20 defines a 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 that provides a rectangular cross-section for the electrode strip 9. The die 230 can naturally be designed in different ways to give the electrode strip 9 other shapes.

[0039] The extruder 2 includes a feed hopper 22 that communicates with the mixing chamber 21, into which the composite material is poured to feed the extruder 2.

[0040] Additionally, the extruder 2 includes an extrusion screw 3 arranged in the mixing chamber 21 such that the main axis I of the extrusion screw 3 coincides with the rotation axis L of the sheath 20.

[0041] According to the invention and as in this example, the extrusion screw 3 includes an outer tube 31, which is mounted such that it rotates autonomously within the mixing chamber 21. The outer tube 31 includes a cylindrical main body 310 and blades 311 arranged helically around the main body 310. As the outer tube 31 rotates, the blades 311 are in motion, mixing the composite material and advancing it longitudinally downstream along the extrusion direction F. The rotation of the outer tube 31 is controlled by a motor (not shown).

[0042] In other words, the blade 311 and the motor constitute a drive device for mixing the composite material and for moving the material toward the extrusion head 23.

[0043] The extrusion screw 3 also includes an inner tube 32, which has a smaller diameter than the outer tube 31 and a longer length than the outer tube 31. Therefore, the inner tube 32 is designed to be partially arranged inside the outer tube 31 and to be arranged coaxially with the outer tube 31.

[0044] Specifically, the inner tube 32 consists of a cylindrical portion 320 and an end 33. The cylindrical portion 320, whose length is substantially equal to that of the outer tube 31, is located inside the outer tube 31. As for the end 33, it is located outside the outer tube 31. In other words, the end 33 is located after the mixing section where the outer tube 31 and its blades 311 are located.

[0045] like Figure 1 , Figure 2 and Figure 4 As shown, end 33 includes a cylindrical portion 333 followed by a hemispherical portion 331. Viewed from the side, end 33 in the example has a bullet shape.

[0046] A through slot 330 is formed in the hemispherical portion 331. The through slot 330 is oriented along a transverse direction T perpendicular to the extrusion direction F. The extrusion direction F and the transverse direction T are in a horizontal plane.

[0047] Furthermore, the inner tube 32 remains stationary relative to the sheath 20 and therefore does not follow the rotational movement of the outer tube 31. In this case, a ball bearing 34 is placed between the two tubes to allow the movement of the two tubes to be independent.

[0048] During the operation of extruder 2, the composite material moved by the outer tube 31 and its drive mechanism is at risk of entering the space between the outer tube 31 and the inner tube 32. To prevent this penetration, a sealing member is placed between the two tubes.

[0049] In this case, a sealing member 35 is placed at end 33. Specifically, as follows: Figure 4 As can be seen from the image, the end 33 includes a cylindrical skirt 332 oriented parallel to the extrusion direction F.

[0050] 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 can be a lip seal or a sealing ball bearing, thereby ensuring both the rotation of the outer tube 31 and the stationary nature of the inner tube 32.

[0051] According to the invention and as shown in the example, the device 1 further includes a feeding and unwinding device configured to convey the current collector belt 5 along the extrusion direction F through the inner tube 32 to the extrusion head 23. The current collector belt 5 exits the extruder 2 through the die 230.

[0052] In this configuration, the advance and unwinding device comprises two pairs of rotating rollers 4 arranged upstream and downstream of the extruder 2, respectively. Each of these pairs of rotating rollers 4 consists of a lower roller 41 for unwinding and an upper roller 42 for advance.

[0053] The two rotating rollers 4 are positioned at the same height to ensure that the current collector belt 5 is parallel to the extrusion direction F.

[0054] Furthermore, the multiple rotating roller pairs 4 are positioned relative to the extruder 2 such that when the current collector belt 5 enters the inner tube 32, the belt is suspended (i.e., it does not contact the wall of the inner tube 32). To facilitate the suspension of the belt 5, in addition to positioning the multiple rotating roller pairs 4 relative to the extruder 2, the dimensions of the current collector belt 5 can be determined such that its width is smaller than the diameter of the inner tube 32. In this way, friction between the current collector belt 5 and the interior of the inner tube 32 is avoided.

[0055] The suspension state of the current collector 5 in the inner tube can be Figure 3 A and Figure 3 See B.

[0056] exist Figure 3 As shown in section C, the current collector band 5 exits the inner tube 32 through a through-slot 330. The cross-section of this through-slot is slightly larger than the cross-section of the current collector band to prevent any contact between the through-slot 330 and the current collector band 5. The through-slot 330 constitutes the outlet of the inner tube 32.

[0057] The arrangement of the multiple rotating roller pairs 4 with the extruder 2 can also be configured such that the manifold 5 is in the plane of symmetry of the extruder 2. In this case, the plane of symmetry of the extruder 2 is a horizontal plane passing through the axis of rotation L of the sheath 20 and thus through the main axis I of the extrusion screw 3, since these two axes coincide. Because the manifold 5 is positioned in the plane of symmetry, both sides of the manifold 5 are covered with the same amount of composite material as soon as it leaves the inner tube 32. This ensures that the pressure is evenly distributed on each side of the manifold 5, thus preventing the manifold tangling or coiling.

[0058] Furthermore, the geometry of the end 33 also helps prevent deformation of the current collector 5 during the deposition of the composite material. Specifically, as explained above, the end 33 is formed of smooth walls. This allows for reduced rotational movement of the composite material when in contact with the end, thereby enabling the composite material to be advanced by translational movement.

[0059] Furthermore, due to the circular shape of the hemispherical portion 331, the composite material is gradually guided to the through slot 330, which serves as the outlet, from which the current collector 5 emerges. Therefore, the deposition of the composite material on the current collector is carried out in a smooth and finely tuned manner.

[0060] At the outlet of extruder 2, a double-coated electrode strip is obtained, which consists of a current collector strip 5 and two layers of composite material 6 located on either side of the current collector strip.

[0061] Optionally, to facilitate the mixing of composite materials in the mixing chamber, heating equipment 7 can be arranged around the sheath 20.

[0062] The apparatus 1 further includes a drying device 8, which is positioned downstream of the extruder 2 to secure the multilayer composite material 6 onto the manifold 5. The drying device 8 can use either cold or hot air, depending on the properties of the composite material.

[0063] Following the drying unit 8 is the rolling station 43, which includes two counter-rotating rollers through which the dried electrode strip passes.

[0064] Following this rolling step, electrode strip 9 is wound around the mandrel to form an electrode coil ready for storage. Alternatively, the double-coated electrode strip is then cut to produce individual electrodes.

[0065] The electrodes formed by electrode strip 9 allow for a reduction in the number of current collectors in the battery and thus a smaller battery size. Therefore, the smaller battery size addresses the limitations associated with increasingly limited space in engine compartments.

Claims

1. An apparatus (1) for manufacturing an electrode strip (9) for a battery, the electrode strip (9) comprising at least one layer of electrochemically active composite material (6) and a current collector strip (5), the manufacturing apparatus (1) comprising: -Extruder (2), the extruder comprising: -Sheath (20), which defines the mixing chamber (21), - An extruder (23) that delivers the electrode strip (9), thereby allowing the extruder to maintain the shape of the electrode strip; and - An extrusion screw (3) is arranged in the mixing chamber (21). The manufacturing equipment (1) is characterized by: The extrusion screw (3) includes: - Outer tube (31), which is mounted such that it rotates on its own in the mixing chamber (21), the outer tube (31) including a drive device configured to mix the active composite material in the mixing chamber (21) and move the material downstream toward the extruder (23); - An inner tube (32) is arranged at least partially inside the outer tube (31) and coaxially with the outer tube (31). The inner tube (32) is stationary relative to the sheath (20) and includes an outlet located upstream of the extruder head (23). The inner tube (32) includes an end (33) located outside the outer tube (31) and formed by a smooth wall. The manufacturing equipment includes a feed and unwind device (4, 41, 42) configured to convey the current collector belt (5) through the inner tube (32) to the extruder head (23).

2. The device (1) as claimed in claim 1, characterized in that, The extruder (2) and the feed and unwind devices (4, 41, 42) are arranged relative to each other in such a way that the current collector (5) is suspended inside the inner tube (32).

3. The device (1) as claimed in claim 1 or claim 2, characterized in that, - The sheath (20) has a rotational shape, the axis of rotation (L) of which coincides with the main axis (I) of the extrusion screw (3); and - The main axis (I) lies in the plane passing through the current collector (5).

4. The device (1) as claimed in claim 1, characterized in that, The end (33) includes a hemispherical portion (331), and the outlet is located at the tip of the hemispherical portion (331).

5. The device (1) as claimed in claim 1 or claim 4, characterized in that, The device includes a sealing member (35) disposed between the end (33) and the outer tube (31).

6. The device (1) as claimed in claim 5, characterized in that, The end (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.

7. The device (1) as claimed in claim 1 or claim 2, characterized in that, The equipment includes a heating device (7) arranged around the extruder (2).

8. The device as claimed in claim 1 or claim 2, characterized in that, The equipment includes a drying unit (8) arranged downstream of the extruder (2).

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