Dry electrode manufacturing plant and associated dry manufacturing process

Abstract

The invention relates to a manufacturing installation for implementing a process for manufacturing electrodes for battery cells, comprising at least one inspection step of at least one component selected from a calendered active electrode material film (2), a current collector foil (3), and a laminated electrode strip (1) by at least one pair of infrared cameras so as to inspect, during conveying, both the first face (1A, 2A, 3A) of the associated component and the opposite second face (1B, 2B, 3B). (Fig. 1)

Description

Title of the invention: Dry electrode manufacturing installation and associated dry manufacturing process Technical field of the invention

[0001] The invention relates, in general, to the field of non-destructive testing of materials.

[0002] The invention relates more specifically to a dry-process electrode manufacturing installation for battery cells and to an associated dry-process manufacturing method. Prior art

[0003] Motor vehicles with electric or hybrid traction or propulsion include one or more battery modules connected to a power network to supply an electric motor (traction or propulsion).

[0004] The battery modules are grouped in a casing and together form a battery block, also often referred to by the English expression "battery pack", this casing generally containing a mounting interface and connection terminals.

[0005] Each battery module is an assembly comprising several electrochemical cells generating current by chemical reaction, for example of lithium-ion (or Li-ion), Ni-Mh, Ni-Cd or lead type.

[0006] An electrochemical cell comprises, in particular, a stack of positive electrodes connected to each other and a stack of negative electrodes connected to each other, separated by a separator, known as a "stack". The positive electrodes are connected to each other at a positive terminal, and the negative electrodes are connected to each other at a negative terminal.

[0007] To obtain the electrodes for the electrode stack, there are various electrode manufacturing processes. In particular, these processes can be divided into two categories: wet coating with solvents and so-called "dry" manufacturing, that is, without the use of organic solvents. While the first option requires the preparation and use of a liquid ink that must subsequently undergo a solvent drying step, the second option eliminates this step and thus offers considerable advantages, particularly in terms of reducing manufacturing time, production costs, energy consumption, and the environmental impact of the process.

[0008] The "dry" manufacturing process for the electrodes of an electrode stack generally comprises: • a step of preparing a dry powder of active electrode material, the step consisting of mixing dry particles of active electrode material and dry particles of binder material; • a calendering step, allowing the dry powder of active electrode material to be compressed by passing it through one or more openings formed between calendering rollers with opposite directions of rotation in pairs, the calendering step allowing a film of active electrode material to be obtained from the dry powder of active material; • a step of cutting the film into a plurality of strips, so as to divide the film into strips configured to equip an electrode, said strips being obtained by cuts made in the direction of movement of the film; • a step of rolling the strips of active electrode material onto at least one side of a current collector strip, to form an electrode comprising the current collector and the plurality of strips of active electrode material rolled onto the collector; • a step of cutting the electrode with the strips of active material so as to obtain a plurality of unit electrodes of battery cells, which will have to be stacked.

[0009] A pervasive problem in the "dry" manufacturing of electrodes concerns the detection of various defects occurring during electrode fabrication. These defects can include, for example, the presence of foreign particles, holes or voids, delamination between the active layers and the current collectors, inconsistencies in charge (surface mass of material) and porosity in the calendered active material film, etc.

[0010] To check for the presence of foreign particles, holes, and voids, optical detection methods are known. Such detection methods provide satisfactory results for particles or irregularities on the surface only, but do not allow for the identification of particles, cavities, or other irregularities deep within the material being checked.

[0011] Potential material delamination, particularly in the case of delamination between the active layers and the current collectors, can be detected by sampling electrodes from mass production. However, such sampling implies that defects are identified only on sampled portions, but not all (100%) of the electrode defects.

[0012] Heterogeneities in charge and porosity can be monitored, for example, by measuring gauges, preferably non-contact gauges such as Beta transmission gauges or electromagnetic radiation gauges (X-rays, Terahertz, etc.). These measuring instruments allow for local measurements to be taken with mobile instruments. way to move around to take measurements ("travelling"). Here again, the defects are identified only on localized portions, but these measuring instruments do not allow the identification of all (100%) of the defects in the electrodes.

[0013] Another alternative technique would be to perform infrared thermographic inspections on the electrodes. However, the accuracy of detecting deep defects is rather limited, and an additional cost is incurred because its implementation generally requires the addition of electrode heating means.

[0014] Furthermore, the installations and processes for manufacturing electrodes by wet process for battery cells are not transferable to those by dry process. Indeed, the characteristic thicknesses of the active material layers of electrodes by wet and dry process can be very different, it being understood that the total thickness of the double-sided electrode is twice the thickness of the active material, to which is added the thickness of the current collector foil.

[0015] For electrodes manufactured by wet process, average thicknesses of around 80 µm are obtained, and can reach up to 120 µm. Beyond these thicknesses, process limitations (difficulty in drying the solvent) and product limitations (cell difficult to load) are generally encountered.

[0016] For electrodes manufactured by dry casting, average thicknesses of around 150 µm, and up to 240 µm, are preferentially obtained: the process has no thickness limitation (on the contrary, the thicker the electrode, the less stress is placed on the calendering rollers), and the chargeability of the electrodes—of the product—is significantly improved, allowing for thicker electrodes to optimize costs. This improved chargeability is achieved in particular by using binders that are less opaque to the active material particles and by creating porosities more favorable to ionic circulation.

[0017] There is therefore a need, especially for electrodes manufactured by dry process, on the one hand to improve the minimum size of defects to be detected in thicker electrodes and therefore more difficult to control (particularly in the core), and to carry out control of the entire electrodes and not just samples, while reducing the costs associated with quality control. Description of the invention

[0018] The invention aims to remedy all or part of the disadvantages of the prior art by proposing in particular a solution enabling more effective control of the various possible defects present during the manufacture of electrodes by dry process, in a reliable, uncomplicated and inexpensive manner.

[0019] To this end, according to a first aspect of the invention, a dry-process electrode manufacturing installation for battery cells is proposed, the installation including laminating means for laminating at least one film of active electrode material onto one face of a current-collecting strip to form a laminated electrode strip, and conveying means comprising: - upstream conveying means to convey the electrode active material film(s) and the current collector strip each along an associated upstream conveying path to the rolling means; - downstream conveying means to convey the rolled electrode strip along a downstream conveying path, from the rolling means to storage means; the conveying means comprising conveying rollers, including at least one pair of adjacent rollers rotating in opposite directions and between which circulates a portion of an associated component selected from the active electrode material film, the current collector strip and the laminated electrode strip, such that the conveying path of the associated component locally presents, against the successive rollers of the pair of adjacent rollers, a sinuous trajectory,

[0020] each of said rollers of the associated pair of adjacent rollers being configured to apply a temperature gradient locally on the associated component selected from the electrode active material film, the current collector foil and the laminated electrode strip, when said component is in contact with the associated roller,

[0021] the installation further comprising at least one pair of infrared cameras associated with a given pair of adjacent rollers, such that for the associated pair of infrared cameras: - a first infrared camera of the associated infrared camera pair is configured to monitor at least a portion of a first face among the first and second opposite faces of the component selected from the electrode active material film, the current collector foil, and the associated laminated electrode strip, when the second face is in contact with a first roll among the rolls of the associated adjacent roll pair; and - a second infrared camera of the associated infrared camera pair is configured to monitor at least a portion of a second face among the first and second opposite faces of the component selected from the electrode active material film, the current collector foil and the associated laminated electrode strip, when the first face is in contact with a second roll among the rolls of the associated adjacent roll pair.

[0022] Thanks to such a combination of features, it is possible to inspect a portion of a component selected from the active electrode material film, the current collector foil, and the laminated electrode strip simply using a pair of infrared cameras, each oriented towards a distinct side of the component. Indeed, each infrared camera inspects a distinct face of the associated component.

[0023] Both sides of the component are thus checked (and not just the two sides of the electrodes): defects in the electrodes in depth can therefore be detected more precisely (minimum detectable defect size) since the accuracy of infrared (or “IR”) thermography depends on several parameters, including the distance between the analyzed surface and the defect.

[0024] The rollers of the pair of adjacent rollers are also configured so that their cylindrical drive wall comes into contact, during conveying, with the component selected from among the active electrode material film, the current collector strip, and the laminated electrode strip. The component, locally driven by the associated conveying roller, comes into contact with it and is heated, for example, by heat transfer, in particular by thermal conduction. The configuration of the adjacent rollers, which allows the associated component to be conveyed along the associated conveying path in a sinuous trajectory, ensures a contact surface on each side of the component, on both of its faces. Each roller thus locally forms a right-angle drive of the associated conveyed component to increase the local contact surface between the conveyed component and said associated conveying roller.

[0025] An infrared camera converts infrared radiation into a visual image representing the surface temperatures of an object, for example, in shades of gray, and an embedded algorithm correlates these shades to the temperature values. The main components of an IR camera are: a detector, a lens, possibly a cooler for the detector, and the electronics. Such infrared cameras are used in combination with image processing and display modules; in other words, means for processing the images read by the IR cameras.

[0026] Thus, by controlling the associated component in a control zone at the level of the rollers of the pair of associated adjacent rollers configured to apply an associated temperature gradient with respect to the direction of conveying the component, the heating of the belt makes it possible to improve the detection of defects highlighted more easily by IR cameras because such temperature variations improve the topographic gradient of the image read by the associated IR camera.

[0027] According to one embodiment, the upstream conveying means are configured to convey two films of active electrode material and the current collector strip each along a separate upstream conveying path associated with the rolling means configured to laminate one of the two electrode active material films onto each face of a current collector strip to form a laminated electrode strip.

[0028] According to one embodiment, each film of active electrode material is calendered by associated calendering means having two main calendering rollers forming conveying rollers and configured to calender a powder of an active electrode material.

[0029] According to one embodiment, the calendering means also include complementary calendering rollers forming conveyor rollers and placed successively to the main calendering rollers along the associated upstream conveyor path.

[0030] According to one embodiment, the rollers of the pair of adjacent rollers are calendering rollers.

[0031] According to one embodiment, the rollers of the pair of adjacent rollers are downstream conveying rollers selected from the downstream conveying means.

[0032] According to one embodiment, the manufacturing installation comprises a plurality of said pairs of adjacent rollers and a plurality of pairs of infrared cameras, each associated with a given pair of adjacent rollers.

[0033] According to one embodiment, the manufacturing installation includes at least one pair of complementary infrared cameras configured to locally control a portion of an associated component selected from the electrode active material film, the current collector foil and the laminated electrode strip in a control area located at, or directly downstream of, one of the means for applying a temperature gradient with respect to the associated conveyor path.

[0034] According to one embodiment, at least one pair of complementary infrared cameras is configured to monitor a portion of current-collecting strip that is located directly downstream of preheating means and upstream of rolling means, on the associated conveyor path.

[0035] According to another aspect of the invention, it relates to a dry manufacturing process for battery cells using an installation as described above, the manufacturing process being notable in that it includes at least one control step of at least one component selected from the active electrode material film, the current collector foil and the laminated electrode strip by at least one pair of infrared cameras so as to control, during conveying, the first face of the associated component and the second opposite face in an associated control zone.

[0036] According to one embodiment, the electrode manufacturing process includes at least one control step of each of the components among the active electrode material films and the laminated electrode strip, by a pair of associated infrared cameras so as to control, during conveying, the first face of the associated component and the second opposite face in the associated control zone. Brief description of the figures

[0037] Other features and advantages of the invention will become apparent from the following description, with reference to the accompanying figures, which illustrate: • [Fig.1]: a schematic view of an installation for manufacturing electrodes for battery cells according to one embodiment; • [Fig.2]: a schematic view of an electrode manufacturing installation for battery cells according to another embodiment; • [Fig.3]: a detailed view of [Fig.2].

[0038] For clarity, identical or similar elements are identified by identical reference signs throughout the figures.

[0039] In the description and claims, to clarify the description and claims, the terminology longitudinal, transverse and vertical shall be adopted without limitation with reference to the X, Y, Z trihedron indicated in the figures, detailed description of an embodiment

[0040] Figures 1 to 3 illustrate electrode manufacturing facilities 10 for battery cells according to two embodiment variants, such facilities 10 enabling the implementation of an electrode manufacturing process.

[0041] Such an installation allows, in particular, the production of laminated electrode strips 1. The laminated electrode strips 1 obtained here are double-sided, that is to say, they have a film of active electrode material 2 arranged on both sides of a central current-collecting strip 3. In other words, a first film of active electrode material 2 is applied to one side of the current-collecting strip 3, and a second film of active electrode material 2 is applied to a second side of the current-collecting strip 3, opposite the first side. The distance between the first and second sides defines the thickness of the current-collecting strip 3. The manufacturing process here is a so-called dry process, that is to say, without the use of solvents.

[0042] A "dry manufacturing process" is defined as a process that uses a dry active electrode material for the manufacture of battery electrodes, such a process not requiring liquid components (solvents) or a drying step. "Active electrode material" is defined as a mixture of an active material, a binder, and optionally a conductive material.

[0043] In the context of the invention, an "active electrode material" refers to a material or a plurality of materials that contribute to the charging and discharging of the electrodes. For the anode, for example, the active electrode material may comprise graphite, silicon carbide (SiC), or silicon dioxide (SiOx). For the cathode, for example, the active electrode material may comprise a nickel, manganese, and cobalt (NMC) mixture, a lithium, iron, and phosphate (LFP) mixture, a lithium, manganese, iron, and phosphate (LMFP) mixture, and so on. Such active electrode materials are capable of redox reactions through the exchange of alkali ions and electrons in the environment of an electrolyte. They are therefore the active materials for electrochemical reactions used particularly in electrochemical cells such as those used in automotive batteries.

[0044] To obtain the laminated electrode strip 1, the installation 10 includes rolling means 20. The rolling means 20 are configured to laminate the two films of active electrode material 2 onto the current collector strip 3, each film of active electrode material 2 being laminated onto one of the distinct sides of the current collector strip 3.

[0045] The rolling means 20 comprise rolling elements, and more particularly two rolling rollers 22, of which a first rolling roller 22A and a second rolling roller 22B. The two rolling rollers 22 are adjacent.

[0046] Each of the rolling rollers 22 comprises a main body 16 of cylindrical shape with a circular base. Each of the rolling rollers 22 extends along a transverse axis parallel to a transverse reference axis Y and extends between two ends along a central axis of elongation of the main body 16 parallel to the transverse reference axis Y. Each of the rolling rollers 22 has a pivot joint whose axis of the pivot joint coincides with the associated central axis. In other words, the two rolling rollers 22 each have an axis of rotation parallel to the transverse reference axis Y. The two axes of rotation of the first and second rolling rollers 22A, 22B are coplanar in a horizontal plane Ph. The main body 16 of each of the first and second rolling rollers 22A, 22B comprises a continuously smooth and homogeneous cylindrical outer surface 18, in other words without holes.

[0047] The first and second rolling rollers 22A, 22B have axes of rotation parallel to the transverse axis Y and also have opposite directions of rotation, and preferably identical speeds. Rotation control means (not shown) allow the rotation of the first and second rolling rollers 22A, 22B to be controlled, which are synchronous. Furthermore, the first and second rolling rollers 22A, 22B are located at a distance from each other of in order to form a gap of predetermined width: this predetermined space separates the first 22A and second 22B rolling rollers through which the two electrode active material films 2 are laminated onto the current collector strip 3. With reference to the figures, the width of the gap is measured along an axis orthogonal to the transverse reference axis Y. Here, since the axes of rotation of the first and second rolling rollers 22A, 22B are coplanar in a horizontal plane Ph, the width of the gap is measured longitudinally. This space is predetermined so as to apply a predetermined compression to the laminated electrode active material films 2 and to the current collector strip 3. The space between the first and second rolling rollers 22A, 22B defines a lamination zone 24 within which the current collector strip 3 and the electrode active material films 2 are laminated.This rolling zone 24 is centered at the minimum distance between the two adjacent rolling rollers 22 such that: . • upstream of this rolling zone 24, the current collector strip 3 and the active electrode material films 2 are separated from each other; • downstream of this rolling zone 24, the rolled electrode strip 1 is obtained.

[0048] Upstream conveying means 30, 30A, i.e. upstream of the rolling relative to the direction of conveying, are configured to convey each of the two films of active electrode material 2 along an upstream conveying path W2A, W2B associated to the rolling means 20, in particular to the rolling zone 24.

[0049] The upstream conveying means 30, 30A are also configured to convey the current collector strip 3 along an associated upstream conveying path W3 to the rolling zone 24.

[0050] Downstream conveying means 30, 30B, i.e. downstream of the rolling relative to the direction of conveying, for conveying the rolled electrode strip 1 along a downstream conveying path Wl, from the rolling means 20 to storage means 50 for storing the rolled electrode strip 1, for example in the form of a winding around a storage roller.

[0051] The upstream and / or downstream conveying means 30, 30A, 30B include, in particular, conveying rollers 30'. These rollers may have other functions than simple conveying and include, in particular, rolling rollers and calendering rollers.

[0052] Each film of active electrode material 2 is obtained by calendering, this calendering operation being carried out by calendering means 40. The calendering means 40 are configured to calender a powder 2' of the active electrode material intended to take the form of a film of active electrode material 2.

[0053] In particular, the installation 10 is configured to produce two films of electrode active material 2, each intended to be applied to a separate side of the current collector strip 3. The calendering means 40 include, in particular, a first pair and a second pair of main calendering rollers 41, 42 for manufacturing the two films of electrode active material 2. A given pair of main calendering rollers 41, 42 is associated with the manufacture of only one of the two given films of electrode active material 2. The two main calendering rollers 41, 42 of the same pair of calendering rollers are adjacent and separated by a predetermined gap through which the powder 2' of the electrode active material is calendered. Naturally, the distance between the two main calendering rollers 41, 42 of the associated pair of rollers determines the thickness of the resulting film of electrode active material 2.This calendering step makes it possible to obtain a film of active electrode material 2 whose thickness and density depend on the distance and differential speed between the main calendering rollers 41, 42 of the same pair of calendering rollers.

[0054] The 2" powder of active material is poured by gravity into a 2" discharge hopper to feed the calendering rollers. Preferably, the 2" powder of active material comprises a mixture of electrode active material particles and binder material particles.

[0055] The 2” discharge hopper is a fixed hopper which has a funnel shape and opens into an opening formed between the two main calendering rollers 41, 42 of the associated roller pair, the width of the opening corresponding to the distance between these two main rollers 41, 42. According to another embodiment of the invention, the 2” discharge hopper can be an oscillating hopper, which makes it possible to ensure a homogeneous distribution of the powder 2' of active material in the associated opening or gap.

[0056] By passing through the opening, the powder 2' of active electrode material is compressed and sheared by the rotation in opposite directions and at different speeds of the main calendering rollers 41, 42 of the associated pair, which makes it possible to produce the film of active electrode material 2.

[0057] As mentioned, the calendering means 40 include in particular here a first pair and a second pair of main calendering rollers 41, 42, each associated with the calendering of one of the two active electrode material films 2 and each composed of a first main calendering roller 41 and a second calendering roller 42. Each calendering roller has a main body 16 of cylindrical shape with a circular base extending along a transverse axis parallel to the transverse reference axis Y.

[0058] The two central axes of the main calendering rollers 41, 42 of the same pair are coplanar to a horizontal plane, preferably in the horizontal plane Ph. In the embodiments illustrated in Figures 1 to 3, the main calendering rollers 41, 42 of the two pairs of calendering rollers are arranged so that their axes of rotation are coplanar in the horizontal reference plane Ph. The main body 16 of each calendering roller comprises a continuously smooth and homogeneous cylindrical outer surface 18, i.e., without holes.

[0059] The installation 10 also has a reference plane Pv parallel to a reference plane containing the transverse reference axis Y and a vertical reference axis Z orthogonal to the longitudinal reference axes X and transverse reference axes Y. The reference plane Pv therefore defines a vertical plane centered between the two rolling rollers 22. The reference plane Pv is orthogonal to the longitudinal plane Ph so that, during the rolling operations by the rolling means 20, the current collector strip 3 follows a path or conveying circuit locally coplanar with the plane Pv in the rolling zone 24.

[0060] The calendering means 40 for the two electrode active material films 2 and the rolling device 20 define all or part of the first conveying path W2A and the second conveying path W2B, which are separate for each of the two electrode active material films 2. More specifically: • the first pair of main calendering rollers 41, 42 and the first rolling roller 22A of the rolling means 20 are configured to drive the first electrode active material film 2 of the two electrode active material films 2 following the first conveying path W2A; and • the second pair of main calendering rollers 41, 42 and the second rolling roller 22B of the rolling means 20 are configured to drive the second electrode active material film 2 among the two electrode active material films 2 following the second conveying path W2B.

[0061] The calendering means 40 further comprise in these embodiments several additional calendering rollers 43, 44, 45, 46 placed successively along the upstream conveyor path W2A, W2B associated and successively in relation to the main calendering rollers 41, 42 along the corresponding upstream conveyor path W2A, W2B.

[0062] The complementary calendering rollers 43, 44, 45, 46 form conveying means 30, in particular conveying rollers 30', each allowing the conveying of the corresponding electrode active material film 2.

[0063] Of course, the number of additional rollers equipping the installation 10 can vary. Preferably, the axes of rotation of each of the additional calendering rollers 43, 44, 45, 46 are parallel and contained in the horizontal reference plane Ph. For example, in the embodiment of [Fig. 1], the installation 10 comprises two additional rollers 43, 44, while in the embodiment of Figures 2 and 3, the installation 10 comprises four additional rollers 43, 44, 45, 46.

[0064] Generally, a first group of rollers comprising at least the first pair of main calendering rollers 41, 42 followed by the complementary calendering rollers 43, 44, 45, 46 and then the first rolling roller 22A of the rolling means 20 ensure the conveying of the first film of active electrode material 2 among the two films of active electrode material 2 following the first conveying path W2A.

[0065] Similarly, a second group of rollers comprising at least the second main pair 41, 42 of calendering rollers followed by the complementary calendering rollers 43, 44, 45, 46 and then the second rolling roller 22 B of the rolling means 20 ensure the conveyance of the second film of active electrode material 2 between the two films of active electrode material 2 along the second conveying path W2 B.

[0066] The main calendering rollers 41, 42 of a given pair of calendering rollers have opposite directions of rotation. In particular, for each given pair of adjacent main calendering rollers 41, 42 and / or complementary rollers 43, 44, 45, 46, the two associated rollers have opposite directions of rotation.

[0067] The calendering means further include control means (not shown) for controlling the rotational speed of the calendering rollers 41, 42, 43, 44, 45, 46. The main calendering rollers 41, 42 of a given pair of calendering rollers rotate at differential speeds around their first and second axes of rotation, respectively.

[0068] The rollers for a given group of rollers are arranged successively adjacent to each other in pairs and have opposite directions of rotation. Each roller in a given group of rollers is spaced from the others by a predetermined associated gap so as to participate in the calendering process, the associated conveyor path winding between each of the rollers driven in rotation in their respective directions of rotation. The active electrode material film 2 then flows along the associated conveyor path W2A, W2B, passing successively through the given gaps, from the calendering stage to the rolling stage.

[0069] The first and second conveyor paths W2A, W2B are globally symmetrical with respect to the vertical reference plane Pv. More precisely, the The main calendering rollers 41, 42 and auxiliary rollers 43, 44, 45, 46 and the first rolling roller 22A of the first group of rollers are located on the same side of the datum plane Pv, as illustrated in [Fig. 2]. In particular, their axes of rotation are symmetrical with respect to the datum plane Pv to the axes of rotation of the main calendering rollers 41, 42 and auxiliary rollers 43, 44, 45, 46 and the second rolling roller 22B, which are located on the other side of the datum plane Pv. More generally, the central axes of each of the calendering and rolling rollers are parallel in pairs, coplanar with the horizontal datum plane Ph.

[0070] Each of the paths between the first conveyor path W2A and the second conveyor path W2B converge towards the rolling zone 24. One of the two electrode active material films 2 is intended to be conveyed along the first conveyor path W2A while the other electrode active material film 2 is intended to be conveyed along the second conveyor path W2B. The first conveyor path W2A and the second conveyor path W2B meet at the rolling zone 24, between the two rolling rollers 22, and continue downstream of the rolling zone 24 coinciding with the conveyor circuit W1 of the current collector strip 3, forming a laminated electrode strip 1.

[0071] The installation 10 also includes preheating means 26. These preheating means 26 are configured to emit a predetermined amount of heat to preheat each side of the current-collecting strip 3, upstream of the rolling zone 24, in particular before the gap between the two rolling rollers 22A, 22B. The preheating is carried out in such a way as to facilitate the rolling of the active electrode material films 2 onto the current-collecting strip 3 and thus ensure better bonding of said active electrode material films 2 to the current-collecting strip 3.

[0072] The preheating means 26 here comprise infrared lamps directed towards each of the two opposite faces of the current-collecting strip 3, at the preheating zone, through which the portion to be preheated passes on its way to the rolling zone 24. The preheating means 26 may also include, by way of non-limiting example, gas burners or induction furnaces, UV sources, and more generally may be of different types, i.e., powered electrically, by fuel, or by light energy. The preheating means 26 are arranged near a portion of the upstream conveyor path W3 along which the current-collecting strip 3 is intended to pass. The conveyor path W3 runs between the preheating means 26 and then through the rolling means 20, between the two rolling rollers 22A, 22B then continues its path towards a storage roller 50.

[0073] The installation includes means for applying a temperature gradient configured to apply a temperature gradient locally on the associated component selected from the electrode active material film 2, the current collector foil 3 and the laminated electrode strip 1.

[0074] In particular, among the upstream and / or downstream conveying means equipped with such means for applying a temperature gradient, the calendering rollers of the calendering means 40, forming conveying rollers 30', are configured to locally heat the active electrode 2 film associated with their contact. The temperature gradient applied to the associated active electrode 2 film is thus positive to ensure its heating.

[0075] The rolling rollers 22A, 22B also form conveyor rollers 30' equipped with such means for applying a temperature gradient. In other words, the rolling rollers 22A, 22B of the rolling means 20 form conveyor rollers 30' configured to locally heat the active material film of electrode 2 associated with their contact. The temperature gradient applied to the associated active material film of electrode 2 is thus positive to ensure its heating.

[0076] According to the invention, the installation 10 comprises several pairs of infrared cameras 100, 100', 100" configured to locally control an associated component selected from the active electrode material film 2, the current collector foil 3 and the laminated electrode strip 1.

[0077] Each pair of 100, 100', 100" infrared cameras comprises: • a first infrared camera 101,101', 101” of the associated infrared camera pair 100,100', 100” configured to control at least one PI portion of a first face IA, 2A, 3A from among the first and second opposite faces of the component selected from the electrode active material film 2, the current collector foil 3 and the associated laminated electrode strip 1; • a second infrared camera 102,102', 102” of the associated infrared camera pair 100,100', 100” configured to monitor at least one portion P2 of a second face IB, 2B, 3B from among the first and second opposite faces of the component selected from the electrode active material film 2, the current collector foil 3 and the associated laminated electrode strip 1, the second face IB, 2B, 3B being opposite to the first face IA, 2A, 3A.

[0078] With reference to Figures 1, 2 and 3, a first pair 100 of infrared cameras provides monitoring of one of the electrode active material films 2 circulating along of the first upstream conveyor path W2A at a control zone A located between the calendering means 40 and the rolling means 20. The first associated infrared camera 101 is oriented to inspect portions PI of the first face 2A of the associated active electrode 2 film. The second associated infrared camera 102 is oriented to inspect a portion P2 of the second face 2B, opposite the first face 2A, of the associated active electrode 2 film.

[0079] A second pair 100' of infrared cameras provides monitoring of the other electrode active material film 2 flowing along the second upstream conveyor path W2B at a control zone A' located between the calendering means 40 and the rolling means 20. The first associated infrared camera 101' is oriented to monitor portions PI' of the first face 2A of the associated electrode active material film 2. The second associated infrared camera 102' is oriented to monitor a portion P2' of the second face 2B, opposite the first face 2A, of the associated electrode active material film 2.

[0080] Thanks to the invention, it is possible to control in an improved way both sides of the two active layers, i.e. the two films of active material of electrode 2. This improves the minimum size of the defects that can be detected.

[0081] Furthermore, each of the main calendering rollers 41, 42 and the adjacent complementary rollers 43, 44, 45, 46 are configured to apply a local temperature gradient to the associated electrode active material film 2. The calendering rollers, forming conveyor rollers 30', are in particular heated, thereby improving the efficiency of image processing by the infrared cameras 101, 102, 101', 102' during the inspection of the associated portions PI, P2, PI', P2'.

[0082] The calendering rollers are configured to heat to a heating temperature greater than or equal to 80°C, preferably greater than or equal to 120°C, and even more preferably up to 200°C, in order to maximize the detection of defects in infrared thermography.

[0083] The calendering rollers, in particular the main calendering rollers 41, 42 and auxiliary rollers 43, 44, 45, 46, are adjacent in pairs in a horizontal plane Ph. These main calendering rollers 41, 42 and auxiliary rollers 43, 44, 45, 46 are arranged adjacent or side by side successively in pairs along the upstream conveyor path W2A, W2B associated with the corresponding rolling roller 22A, 22B. The corresponding control zones A, A' are therefore located at the level of the heated calendering and rolling rollers forming conveyor rollers 30'.

[0084] Depending on the distance separating each camera from the portion of active material film 2 to be controlled and depending on the field angle of the corresponding infrared cameras, several portions of the same face of active material film of electrode 2 can be controlled simultaneously.

[0085] In the illustrated embodiment, for any pair 300, 300' of adjacent rollers taken from among the main calendering rollers 41, 42 and auxiliary rollers 43, 44, 45, 46 and the associated rolling roller 22A, 22B, the two adjacent rollers of the pair rotate in opposite directions and together guide the electrode active material film 2 such that the conveying path of the associated electrode active material film 2 locally presents a sinuous trajectory against the rollers of the adjacent pair. Thus, each of the electrode active material films 2 is conveyed by the calendering and rolling rollers forming conveying rollers 30' and travels between these rollers along a sinuous path, i.e., zigzagging or winding between said rollers.

[0086] In particular, in these embodiments, the installation 10 comprises: • a first pair 300 of adjacent rollers 301, 302 rotating in opposite directions and between which a portion of one of the electrode active material films 2 circulates such that the associated conveying path W2A of the electrode active material film 2 locally presents, against the successive rollers 301, 302 of the pair 300 of adjacent rollers, a sinuous trajectory; and • a second pair 300' of adjacent rollers 301', 302' rotating in opposite directions of rotation and between which circulates a portion of one of the films of active material of electrode 2 so that the associated conveying path W2 B of the film of active material of electrode 2 presents locally against the successive rollers 301', 302' of the pair 300' of adjacent rollers, a sinuous trajectory.

[0087] As can be particularly seen in [Fig. 3], along each of the upstream conveying paths W2A, W2B the associated electrode 2 active material film flows alternately: • below the upstream adjacent conveyor roller relative to the associated conveyor path W2A, W2B, forming a second roller 302, 302' of the given pair 300, 300' of adjacent rollers: this upstream adjacent conveyor roller being constituted by the calendering roller 44 in the embodiment of [Fig. 1] or the calendering roller 46 in the embodiments of [Fig. 2] and 3; then • above one of the conveyor rollers, here rolling roller 22A, 22B, forming a first roller 301, 301' of a given pair 300, 300' of adjacent rollers.

[0088] Each of the first infrared cameras 101, 101' is positioned so that its field of view includes at least the portion PI, PI' of the first face 2A of the associated active material film of electrode 2 located above the corresponding conveyor roller(s). Each of the second infrared cameras 102, 102' is positioned so that its field of view includes at least the portion P2, P2' of the second face 2B of the associated active material film of electrode 2 located above the corresponding conveyor roller(s).

[0089] Thus, each of the first infrared cameras 101,101' of the corresponding pairs 100,100' controls portions PI, PI' of the first face 2A of the associated electrode 2 active material film when the second face 2B, opposite to the first controlled face 2A, of the associated electrode 2 active material film is in contact with one of the conveyor rollers, here calendering rollers and a rolling roller, in other words when the second face 2B is in contact with the first roller 301, 301' among the rollers of the pair 300, 300' of associated adjacent rollers.

[0090] Similarly, each of the second infrared cameras 102,102' of the corresponding pairs 100,100' controls portions P2,P2' of the second face 2B of the associated electrode 2 active material film when the first face 2A, opposite to the second face 2B being controlled, of the associated electrode 2 active material film is in contact with one of the conveyor rollers, here calendering rollers and a rolling roller, in other words when the first face 2A is in contact with the second roller 302, 302' among the rollers of the pair 300, 300' of associated adjacent rollers.

[0091] The fact that the conveying path of the associated active material film of electrode 2 locally presents a sinuous trajectory against the rollers of the pair of adjacent rollers, offers the possibility of allowing control of the associated active material film of electrode 2 on both sides of the two active layers despite the presence of the calendering rollers while controlling areas of the associated active material film of electrode 2 with heat sources opposite to the camera associated with respect to the audit of the active material film of electrode 2.

[0092] Figure 3 focuses on pairs 300, 300' of rollers. Of course, the same reasoning applies to the calendering rollers 41, 42, 43, 44, 45, 46.

[0093] Thus, in this example, the first camera 101,101' can focus on defect detection on the portion of the active material film of electrode 2 associated in contact with the calendering roller 43, or even on different portions of the active material film of electrode 2 associated with the contact of the calendering roller 43 on the one hand and also with the contact of the corresponding rolling roller 22A, 22B and where applicable also with the contact of the calendering roller 45. In this case the second camera 10 2,10 2 ' can focus on the detection of defects on the portion of the active material film of electrode 2 associated with the contact of the calendering roller 42, or even on different portions of the active material film of electrode 2 associated with the contact of the calendering roller 42 on the one hand and also with the contact of the calendering roller 44, and where applicable also with the contact of the calendering roller 46.

[0094] In the embodiment of [Fig.1], the installation includes a third pair of 100” infrared cameras.

[0095] The third pair 100” of infrared cameras 101”, 102” provides monitoring of the laminated electrode strip 1 traveling along the downstream conveyor path W1 at a control zone A” located between the rolling means 20 and the storage means 50. The first associated infrared camera 101” is oriented to monitor portions PI” of the first face IA of the laminated electrode strip 1. The second associated infrared camera 102” is oriented to monitor a portion P2” of the second face IB, opposite the first face IA, of the laminated electrode strip 1.

[0096] In particular, the installation 10 includes along this downstream conveyor path W1 conveyor rollers 30'. On this conveyor path W1, the laminated electrode strip 1 travels until it passes through a post-rolling workstation.

[0097] This downstream workstation comprises a pair 300” of adjacent rollers 301”, 302” rotating in opposite directions and between which the laminated electrode strip 1 is passed, such that the conveying path of the associated component locally presents, against the rollers 301”, 302” of the pair 300” of adjacent rollers of the downstream workstation, a sinuous trajectory. These adjacent rollers 301”, 302” form rollers 30’ participating in the conveying of the laminated electrode strip 1.

[0098] The 30' conveyor rollers of the downstream workstation are configured to apply a temperature gradient locally on the laminated electrode strip 1, this to improve the thermal contrast read by the associated pair of infrared cameras.

[0099] Analogously to the first and second pairs of infrared cameras 100, 100', the first infrared camera 101'' of the corresponding pair 100'' monitors a portion PI" of the first face IA of the laminated electrode strip 1 when the second face IB, opposite to the first monitored face IA, of the laminated electrode strip 1 is in contact with one of the two associated conveyor rollers, otherwise said when the second face IB is in contact with the first 301” roller of the associated 300” pair of adjacent rollers.

[0100] Similarly, the second infrared camera 10 2' ' of the corresponding pair 100 ' ' controls a portion P 2” of the second face IB of the laminated electrode strip 1 when the first face 1 A, opposite to the second face IB being controlled, of the laminated electrode strip 1 is in contact with the other of the two associated conveyor rollers, in other words when the first face IA is in contact with the second roller 302” of the associated pair 300” of adjacent rollers.

[0101] In summary, in this advantageous embodiment, the installation 10 comprises: • pairs 300, 300' of adjacent rollers providing a sinuous trajectory on each of the upstream conveying paths W2A, W2B of the electrode 2 active material film, the adjacent rollers being selected from the rolling rollers 22A, 22B and the calendering rollers 41, 42, 43, 44, 45, 46; and • a pair of 300” adjacent rollers giving a winding path on the downstream conveying path W1 of the rolled electrode strip 1, the adjacent rollers being 30' conveying rollers of the rolled electrode strip 1 exiting the rolling mill; Each of these pairs of adjacent rollers (300, 300', 300") giving a given sinuous trajectory is controlled by an associated pair of infrared cameras (100, 100', 100") such that: • the first infrared camera 101, 101', 101” of the associated infrared camera pair 100, 100', 100” monitors the portion PI, PI', PI” of the first face IA, 2A of the active material film of electrode 2 or the associated laminated electrode strip 1 in a control zone A, A', A” where the second face IB, 2B, opposite the first face IA, 2A being monitored, is in contact with the first roll 301, 301', 301” of the associated pair 300, 300', 300” of adjacent rolls; and • the second infrared camera 102,102', 102” of the associated infrared camera pair 100,100', 100” controls the portion P2, P2', P2” of the second face IB, 2B of the active material film of electrode 2 or of the associated laminated electrode strip 1 in the control area A, A', A” where the first face IA, 2A, opposite to the second face IB, 2B being controlled, is in contact with the second roll 302, 302', 302” of the associated pair 300, 300', 300” of adjacent rolls.

[0102] Naturally, the installation can also be equipped with pairs of complementary 100" infrared cameras configured to locally monitor a portion of an associated component selected from the electrode active material film 2, the current collector foil 3 and the laminated electrode strip 1, these camera pairs complementary differing from other pairs 100,100', 100" of infrared cameras in that they control opposite faces of a portion of the component chosen from the active electrode material film 2, the current collector foil 3 and the laminated electrode strip 1 without this associated portion of the component being in contact with one of the rollers of a given pair of adjacent rollers.

[0103] In this example, it refers to the pair of complementary infrared cameras 100"' for monitoring a portion of current collector strip 3 which is located directly downstream of the preheating means 26 on the associated conveyor path W3. This pair of complementary infrared cameras 100"' comprises a first complementary infrared camera 101"'" configured to monitor a portion of a first face 3A of the current collector strip 3 and a second complementary infrared camera 102"'" configured to monitor a portion of the second face 3B of the current collector strip 3 opposite the first face 3A.

[0104] Generally, each pair of complementary 100” infrared cameras comprises: • a first complementary infrared camera 10 1" ' of the associated complementary infrared camera pair 100" ' configured to monitor at least a portion of a first face IA, 2A, 3A from among the first and second opposite faces of the component selected from the electrode active material film 2, the current collector foil 3 and the associated laminated electrode strip 1; and • a second complementary 102” infrared camera of the associated pair of complementary 100” infrared cameras configured to monitor at least a portion of a second face IB, 2B, 3B from among the first and second opposite faces of the component selected from the electrode active material film 2, the current collector foil 3 and the associated laminated electrode strip 1.

[0105] In summary, the invention makes it possible to ensure quality control of the electrodes during their manufacture, which makes it possible to identify singularities and defects (holes, foreign particles, detachment between the active material and the current collector, heterogeneities of charge and density, etc.)

[0106] Infrared cameras are thus introduced to incorporate thermography into electrode manufacturing by intelligently utilizing the thermal stresses already applied during the manufacturing process. IR thermography is a non-destructive testing method that involves applying thermal stress to a material or part and identifying, using an IR camera, any thermal deviations in order to detect potential singularities or defects. The thermal stress can be applied in different ways depending on the state of the art: external IR heating (lamp), internal heating (induction), with analysis of the transmitted or reflected heat flow, etc.

[0107] Thanks to the invention, natural phases such as the heating phases of electrodes (which are thermal stresses) and IR cameras are used to perform IR thermography. The process is simple and the investment low, since only additional IR cameras are needed, the process naturally generating thermal stresses.

[0108] Indeed, the heat sources, or more generally the thermal stresses used in such an electrode manufacturing installation 10 and implemented in such an associated manufacturing process, are specific to electrode manufacturing, and the use of pairs of infrared cameras to inspect both sides of the same component does not require additional external sources dedicated to IR thermography. For example, the calendering rollers apply thermal stresses necessary for calendering the active material of the associated electrode 2. The same is true for at least some of the conveyor rollers. For these rollers, the thermal stresses are predetermined solely for the purposes of the associated manufacturing step, namely calendering, and it is not necessary to modify them to implement the invention.

[0109] Naturally, the invention is described above by way of example. It is understood that a person skilled in the art is able to carry out different embodiments of the invention without departing from the scope of the invention.

[0110] The invention could also be applied to a wet process for manufacturing electrodes.

[0111] It is emphasized that all features, as they are apparent to a person skilled in the art from the present description, drawings and attached claims, even if in practice they have only been described in relation to other specific features, both individually and in any combinations, can be combined with other features or groups of features disclosed herein, provided that this has not been expressly excluded or that technical circumstances render such combinations impossible or meaningless.

Claims

1. Demands Installation (10) for manufacturing electrodes by dry process for battery cells, the installation (10) comprising laminating means (20) for laminating at least one film of active electrode material (2) onto one face of a current collector strip to form a laminated electrode strip (1), and conveying means (30) comprising: - upstream conveying means (30, 30A) to convey the electrode active material film(s) (2) and the current collector strip (3) each along an associated upstream conveying path (W2A, W2B, W3) to the rolling means (20); - downstream conveying means (30, 30B) to convey the rolled electrode strip (1) along a downstream conveying path (Wl), from the rolling means (20) to storage means (50); the conveying means (30) comprising conveying rollers (30'), comprising at least one pair (300, 300', 300") of adjacent rollers rotating in opposite directions of rotation and between which circulates a portion of an associated component selected from the active electrode material film (2), the current collector strip (3) and the laminated electrode strip (1), such that the conveying path of the associated component locally presents, against the successive rollers of the pair of adjacent rollers, a sinuous trajectory, each of said rollers of the associated pair of adjacent rollers being configured to apply a temperature gradient locally on the associated component selected from the electrode active material film (2), the current collector strip (3) and the laminated electrode strip (1), when said component is in contact with the associated roller, the installation (10) further comprising at least one pair of infrared cameras (100, 100', 100”) associated with a given pair of adjacent rollers (300, 300', 300”), such that for the pair (100, 100', 100”) of associated infrared cameras: - a first infrared camera (101, 101', 101”) of the associated infrared camera pair (100, 100', 100”) is configured to control at least a portion (PI, PI', PI”) of a first face (IA, 2A, 3A) among the first and second opposite faces of the component selected from the electrode active material film (2), the current collector foil (3) and the associated laminated electrode strip (1), when the second face (IB, 2B, 3B) is in contact with a first roller (301, 301', 301”) among the rollers of the associated adjacent roller pair;and - a second infrared camera (102, 102', 102”) of the associated infrared camera pair (100, 100', 100”) is configured to monitor at least one portion (P2, P2', P2”) of a second face (IB, 2B, 3B) from among the first and second opposite faces of the component selected from among the associated active electrode material film (2), current collector foil (3) and laminated electrode strip (1), when the first face (IA, 2A, 3A) is in contact with a second roller (302, 302', 302”) from among the rollers of the associated adjacent roller pair.

2. Electrode manufacturing installation (10) according to claim 1, characterized in that the upstream conveying means (30A) are configured to convey two films of electrode active material (2) and the current collector strip (3) each along a separate upstream conveying path (W2A, W2B, W3) associated to the rolling means (20) configured to roll one of the two films of electrode active material (2) onto each of the faces of a current collector strip (3) to form a rolled electrode strip (1).

3. Electrode manufacturing installation (10) according to claim 1 or 2, characterized in that each film of electrode active material (2) is calendered by associated calendering means (40) having two main calendering rollers (41, 42) forming conveyor rollers (30'), and configured to calender a powder (2') of an electrode active material, the calendering means (40) preferably comprising complementary calendering rollers (43, 44, 45, 46), forming conveyor rollers (30'), and placed successively at the main calendering rollers (41, 42) along the associated upstream conveyor path (W2A, W2B).

4. Electrode manufacturing installation (10) according to any one of the preceding claims, characterized in that the rollers of the pair (300, 300', 300") of adjacent rollers are calendering rollers.

5. Electrode manufacturing installation (10) according to any one of the preceding claims, characterized in that the rollers of the pair (300, 300', 300") of adjacent rollers are downstream conveyor rollers selected from the downstream conveyor means (30, 30B).

6. Electrode manufacturing installation (10) according to any one of the preceding claims, characterized in that it comprises a plurality of said pairs (300, 300', 300”) of adjacent rollers and a plurality of pairs of infrared cameras (100, 100', 100”) each associated with a given pair of adjacent rollers (301, 302, 301', 302', 301”, 302”).

7. Electrode manufacturing installation (10) according to any one of the preceding claims, characterized in that it comprises at least one pair of complementary infrared cameras (100'”) configured to locally control a portion of an associated component selected from the electrode active material film (2), the current collector foil (3) and the laminated electrode strip (1) in a control zone (A”') located at, or directly downstream of, one of the means for applying a temperature gradient with respect to the associated conveyor path.

8. A method for manufacturing electrodes by dry process for battery cells by an electrode manufacturing installation (10) according to any one of the preceding claims, the manufacturing method being characterized in that it comprises at least one inspection step of at least one component selected from the active electrode material film (2), the current collector foil (3) and the laminated electrode strip (1) by at least one pair of infrared cameras so as to inspect, during conveying, the first face (IA, 2A, 3A) of the associated component and the second opposite face (IB, 2B, 3B) in an associated inspection zone (A, A', A”).

9. Method for manufacturing electrodes according to the preceding claim, characterized in that it comprises at least one control step of each of the components among the active electrode material films (2) and the laminated electrode strip (1), by a pair of infrared cameras (100, 100', 100”) associated so as to control, during conveying, the first face (IA, 2A, 3A) of the associated component and the second face (IB, 2B, 3B) opposite in the associated control zone (A, A', A”).

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