SYSTEM FOR CONTINUOUSLY MANUFACTURING AN ELECTRODE AND METHOD FOR THIS

Description

technical field

[0001] The present invention relates to a method for the continuous manufacture of an electrode, for example for a metal-ion battery. Previous techniques

[0002] A metal-ion battery has two electrodes, a positive electrode and a negative electrode, commonly referred to as the cathode and anode respectively, separated by a separator that is electrically insulating but ionically conductive. In the case of a lithium-ion battery, the separator is impregnated with a liquid electrolyte containing lithium ions.

[0003] The positive and negative electrodes are classically manufactured by coating, by continuously depositing an ink containing an active material, a solvent, a binder and possibly an electrically conductive additive, onto the current collectors.

[0004] Traditionally, a drive roller combined with a metering blade roller is used to apply the coating to one side of the collector. Document 2002JP-0073467 discloses a gravity-fed ink coating process using a metering blade roller, also known as a "knife" or "comma bar." The drawback of this process is that it is not possible to coat both sides of the collector simultaneously. To obtain a coating layer on both sides, it is necessary to first coat one side, then repeat all the steps of the process, reversing the direction of the collector, to coat the second side.

[0005] In order to optimize production time by simultaneously coating both sides of a collector, the most commonly used technique is the so-called slot die coating technique.

[0006] US patent 905-06-18-B2 illustrates this technology. Although the process described in this patent allows for coating both faces in a single step, it uses two dedicated coating sources, each located on an opposite face of the collector. This multiplication of dedicated coating sources increases the complexity of the manufacturing system as well as the energy required for its operation. US patent 2010 / 247993 discloses a process for the continuous manufacturing of an electrode. Description of the invention

[0007] The invention aims to reduce the number of dedicated coating sources used for manufacturing electrodes while allowing the continuous and simultaneous creation of a coating layer on each of the two opposite faces of a current collector.

[0008] The invention relates to a continuous manufacturing process for an electrode comprising the following steps carried out simultaneously and continuously: continuous scrolling of a current collector, said current collector having a first face and a second face opposite the first face, continuous deposition of ink on the first face of the current collector from an ink reservoir, said ink comprising at least a solvent and an active material, continuous deposition of ink on the second face of the current collector, continuous drying of the deposited ink to remove the solvent, by a drying device.

[0009] According to this process, the ink deposit on the second side of the collector is achieved by coating it with ink deposited on the first side of the collector.

[0010] Such a process makes it possible to use the same formulation for both sides of the collector from the same ink production and the same dedicated coating source, which promotes better homogeneity of production.

[0011] Such a process makes it possible to reduce the number of dedicated coating sources, thereby reducing the complexity of the manufacturing system as well as the energy expenditure required for its operation.

[0012] According to one feature, the coating of the second face B is carried out in such a way as to transfer half of the ink deposited on the first face of a first collector segment to the second face of a second collector segment located downstream of the first segment in the direction of the collector's movement.

[0013] For example, the coating of the second side is achieved by a simultaneous passage of the collector segments between two rollers spaced at a distance corresponding to the sum of the thicknesses of the segments, the thickness of the dried ink layer on the first side of the second segment, and half the thickness of the ink layer deposited on the first side of the first segment.

[0014] Advantageously, the two segments of the collector form an exit angle of the two rollers ranging from 5 to 45 degrees. Such an exit angle facilitates the separation of the two segments of the collector and allows the gap between the two segments to be maintained for drying in the same drying device.

[0015] Advantageously, the ink is deposited on the first face of the current collector by coating using a metering blade. This coating method is energy-efficient and avoids ink losses caused by the use of pumping systems required by technologies such as slot-die printing.

[0016] For example, the deposited ink layer has a thickness ranging from 50 µm to 400 µm.

[0017] According to another characteristic, the drying device is located downstream of the ink deposition areas, in the direction of the collector's movement.

[0018] For example, ink has a viscosity ranging from 0.001 Pa.s to 10 Pa.s.

[0019] In another aspect, the invention relates to a system for the continuous manufacturing of an electrode comprising: means for continuously scrolling a current collector, said current collector having a first face and a second face opposite the first face, means for continuously depositing ink on the first face of the current collector from an ink reservoir, said ink comprising at least a solvent and an active material, means for continuously depositing ink on the second face of the current collector, a device for continuously drying the ink deposited on the current collector to remove the solvent.

[0020] The ink deposit on the second side of the collector is achieved by coating it with ink deposited on the first side of the collector.

[0021] Preferably, the drying device comprises a single oven associated with an air extraction device. Brief description of the drawings

[0022] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings in which: [ Fig.1 ] schematically illustrates a continuous manufacturing system for an electrode according to an embodiment of the invention; [ Fig. 2 ] is a detailed view of the system of the [ Fig.1 ] ; And [ Fig.3 ] illustrates a flowchart of a continuous manufacturing process for an electrode according to an embodiment of the invention. Detailed description of at least one embodiment

[0023] We have represented on the [ Fig.1 ] a system 1 for the continuous manufacture of an electrode 2 according to an embodiment of the invention.

[0024] The manufacturing system 1 includes means for continuously scrolling 3 a current collector 4 from a first coil 5 located upstream to a second coil 6 located downstream.

[0025] The current collector 4 comprises a first face A and a second face B opposite face A. The current collector 4 is made from a metal sheet or strip. A strip is defined as a plate or band formed from several superimposed films or layers. For example, the current collector 4 is made of copper or aluminum. For example, the current collector 4 has a thickness ranging from 5 µm to 25 µm.

[0026] The manufacturing system 1 includes means for continuously depositing ink 7, 8 onto the current collector 4.

[0027] The deposition means 7 are configured to continuously deposit ink 9 onto the first face A of the current collector 4 from an ink reservoir 10. Preferably, the deposition means 7 include a roller 11 equipped with a metering blade for adjusting the thickness of the ink layer 9 deposited by coating. Preferably, the thickness of the ink layer 9 ranges from 50 µm to 400 µm.

[0028] The ink 9 comprises at least one solvent, one active material, and one polymeric binder enabling the active material to adhere to the current collector. The solvent may be organic or aqueous. The active material may be a positive or negative electrode active material. Preferably, the ink 9 also includes an additive, in particular a carbon-based one. Alternatively, the ink 9 may not contain such an additive.

[0029] For example, the ink has a viscosity ranging from 0.001 Pa.s to 10 Pa.s, and preferably, a viscosity ranging from 0.01 Pa.s to 10 Pa.s.

[0030] The deposition means 8 are configured to continuously deposit ink 9 onto the second face B of the current collector 4, by coating with ink 9 already deposited on the first face A of the current collector 4.

[0031] The deposit means 8 are located downstream of the deposit means 7, in the direction of the flow of the collector 4.

[0032] Such a manufacturing system makes it possible to reduce the number of dedicated coating sources. Thus, in the illustrated example, there is only one dedicated coating source, namely the ink reservoir 10.

[0033] The coating of the second face B is carried out in such a way as to transfer ink 9 deposited on the first face A of a first collector segment 12 to the second face B of a second collector segment 13 located downstream of the first segment in the direction of travel of the current collector 4. Preferably, the coating of the second face allows approximately half of the ink 9 deposited on the first face A of the first collector segment 12 to be transferred to the second face B of the second collector segment 13. Such a coating ensures that the deposited ink layers are of equal thickness between the two faces A and B, within tolerances. Alternatively, it remains possible for the deposited ink layers to have different thicknesses between the two faces A and B of the current collector 4.

[0034] It should be noted that although the first face A of the first segment 12 participates in the coating of the second face B of the second segment 13, it does not constitute a dedicated source of coating.

[0035] Preferably, the coating is achieved by the simultaneous passage of the collector segments 12, 13 between two associated rollers 14a, 14b. The rollers 14a, 14b are spaced at a distance corresponding to the sum of the thicknesses of the segments 12, 13, the thickness of the dried ink layer on the first face A of the second segment 13, and half the thickness of the ink layer deposited on the first face A of the first segment 12.

[0036] Preferably, the distance between rollers 14a, 14b can be adjusted to take into account the manufacturing tolerances of the different elements of the manufacturing system 1, so as to control the thickness of the ink layer 9 deposited on the faces A, B of the current collector 4.

[0037] The manufacturing system 1 further includes a drying device 15 for drying the ink 9 deposited on the current collector 4 so as to remove the solvent from the ink 9. The drying device 15 is located downstream of the ink deposition zones, in the direction of travel of the collector. The ink deposition zones correspond to the locations of the deposition means 7 and 8.

[0038] Preferably, the drying device 15 comprises a single oven 16 associated with an air extraction device (not shown). The temperature of the oven chamber 16 is set constant and ranges from 50 °C to 150 °C. Alternatively, depending on the desired drying dynamics, it is possible to provide for a temperature variation inside the oven chamber 16. Alternatively, it is also possible to provide for several ovens 16.

[0039] The two segments 12, 13 of the current collector 4 form an output angle α of the two rollers 14a, 14b ranging from 5 to 45 degrees ([ Fig. 2 ]), in order to facilitate the separation of the two segments of the collector and to be able to dry them in the same oven 16.

[0040] Alternatively, manufacturing system 1 may include means for calendering and / or cutting (not shown) the electrode formed from the current collector and the active material.

[0041] There [ Fig.3 ] illustrates a flowchart of a continuous manufacturing process for an electrode, according to an embodiment of the invention.

[0042] Although the [ Fig.3 ] illustrates successive steps, it is understood that the steps of the process are carried out simultaneously and continuously.

[0043] The process thus includes a step 17 of continuous scrolling of a current collector, a step 18 of continuous deposition of ink on a first face A of the collector, a step 19 of continuous deposition of ink on a second face B of the collector opposite to the first face A and a step 20 of continuous drying allowing to obtain an electrode.

[0044] In a later step, the electrode can be calendered. This step reduces the electrode's porosity to improve its performance in a battery and increase its energy density.

[0045] The electrode formed by the current collector and the active material can be wound and / or cut to the desired dimensions. This step can be performed at any point in the process once the active material has been deposited on the current collector and the solvent has been removed by drying. For example, this step can be performed before or after calendering. Preferably, the cutting and / or winding steps are performed after the calendering step.

Claims

1. Method for continuously manufacturing an electrode (2), comprising the following steps carried out simultaneously and continuously: - continuously moving a current collector (4), said current collector having a first face (A) and a second face (B) opposite the first face (A), - continuously depositing an ink (9) on the first face (A) of the current collector (4) from a reservoir (10) of ink (9), said ink comprising at least one solvent and one active material, - continuously depositing ink (9) on the second face (B) of the current collector (4), - continuously drying the deposited ink (9) to remove the solvent, using a drying device (15), characterized in that ink is deposited on the second face (B) of the collector (4) by coating with ink deposited on the first face (A) of the collector (4).

2. Method according to Claim 1, wherein the second face B is coated so as to transfer half of the ink deposited on the first face (A) of a first collector segment (12) to the second face (B) of a second collector segment (13) situated downstream of the first segment (12) in the direction of movement of the collector (4).

3. Method according to Claim 2, wherein the second face (B) is coated by simultaneous passage of said segments (12, 13) of the collector between two rollers (14a, 14b) that are spaced apart by a distance corresponding to the sum of the thicknesses of the segments (12, 13), a thickness of a dried ink layer of the first face (A) of the second segment (13) and a half-thickness of a layer of ink deposited on the first face (A) of the first segment (12).

4. Method according to Claim 3, wherein the two segments (12, 13) of the collector (4) form an output angle (α) from the two rollers (14a, 14b) that ranges from 5 to 45 degrees.

5. Method according to any one of the preceding claims, wherein ink is deposited on the first face (A) of the current collector (4) by coating using a metering blade.

6. Method according to any one of the preceding claims, wherein the deposited ink layer has a thickness ranging from 50 µm to 400 µm.

7. Method according to one of the preceding claims, wherein the drying device (15) is situated downstream of the ink deposition zones, in the direction of movement of the collector.

8. Method according to any one of the preceding claims, wherein the ink (9) has a viscosity ranging from 0.001 Pa.s to 10 Pa.s.

9. System for continuously manufacturing an electrode (2), comprising: - means (3) for continuously moving a current collector (4), said current collector having a first face (A) and a second face (B) opposite the first face (A), - means (7) for continuously depositing an ink (9) on the first face (A) of the current collector (4) from a reservoir (10) of ink (9), said ink comprising at least one solvent and one active material, - means (8) for continuously depositing ink (9) on the second face (B) of the current collector (4), - a device (15) for continuously drying the ink deposited on the current collector (4) to remove the solvent, characterized in that ink is deposited on the second face (B) of the collector by coating with ink deposited on the first face (A) of the collector.

10. System according to Claim 9, wherein the drying device (15) comprises a single oven (16) associated with an air extraction device.