Dry manufacturing process for electrodes and associated assembly

Abstract

The invention relates to a dry manufacturing process for electrodes (90) for battery cells, the manufacturing process being characterized in that it comprises at least: (i) a step of cutting lateral edges (51) of a film (50) of active electrode material so as to obtain a pre-cut film (60) of predetermined width measured between its lateral edges (51); (ii) a step of cutting the pre-cut film (60) of active electrode material so as to divide the pre-cut film (60) into a plurality of cut strips (70) of active electrode material, each of said cut strips (70) of active electrode material being configured to equip one or two electrodes (90), the predetermined width of the pre-cut film (60) being equal to the sum of the widths of each of the cut strips (70) in the pre-cut film (60);(iii) a step of rolling at least one diced strip (70) of electrode active material from the plurality of diced strips (70) onto at least one face of a current collector strip (75), to form a laminated electrode strip (80). (Fig. 1);

Description

Title of the invention: Dry manufacturing process for electrodes and associated assembly Technical field of the invention

[0001] The invention relates, in general, to the technical field of battery cells.

[0002] The invention relates more specifically to a dry manufacturing process for battery cell electrodes, and to an associated assembly for manufacturing the electrodes. 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, the latter being described in the remainder of this application. 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] A "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 main strips configured to equip an electrode, each separated by intermediate strips, by cuts made in the direction of movement of the film, so as to obtain a plurality of main strips of active electrode material spaced two by two with a predetermined width corresponding to the space previously occupied by the intermediate strips cut and removed, the main strips being wider than the intermediate strips cut; • a step of rolling the plurality of main strips of electrode active material onto at least one side of a current collector strip, to form an electrode comprising the current collector and the plurality of main strips of electrode active material rolled onto the collector and spaced two by two of the predetermined width; • a step of cutting the electrode with the main bands of active material, in the direction of movement of the electrode, on either side and in the middle of each main band of active material of the electrode, and finally in a direction perpendicular to the direction of movement of the electrode, so as to obtain a plurality of unitary electrodes of battery cells, which will have to be stacked.

[0009] However, such a process, while offering considerable advantages over wet coating manufacturing processes, requires, during the step of cutting the film into a plurality of strips, the removal of intermediate strips of predetermined width to form the plurality of main strips of electrode active material. This removal results in considerable losses of electrode active material film, which could be used to produce electrodes. More specifically, the cut intermediate strips must be recycled or discarded, which significantly increases the cost of manufacturing the electrodes.

[0010] Furthermore, to facilitate the rolling step, it is common to add primary coating strips to the current collector strip, allowing the main strips of electrode active material to adhere more easily to the strip. current collector. Preferably, the width of the primary coating strips is equal to the width of the main strips.

[0011] However, with the removal of the intermediate strips of the active material film, simultaneous alignment between the plurality of main strips of electrode active material and the primary coating strips formed on the current collector strip is difficult to ensure, because the main strips are conveyed on a roller on which they can become misaligned

[0012] Furthermore, the intermediate strips cut are narrow, ranging from 10 to 80 mm depending on the final cell design and the requirements for connecting the electrodes to the cell terminals. Therefore, precise cutting tools placed close together are necessary for the cutting step, resulting in high installation and maintenance costs, as well as increased misalignment of the cutting tools on the active electrode material film. These cutting tools are generally circular knives in contact with the calendering rollers, which presents risks of generating metallic particles as the knives and rollers wear, thus increasing the risk of contamination in the electrodes and cells. This can potentially lead to internal short circuits (self-discharge) or even unintended events (thermal runaway) in the cell.

[0013] Finally, this process requires, particularly for the calendering step, wide calendering rollers. However, a significant width of these rollers increases their deflection and therefore impacts the flatness and homogeneity of the electrode active material films formed during this step. Furthermore, the cost of using wider calendering rollers and their maintenance must be taken into account. Description of the invention

[0014] The invention aims to remedy all or part of the disadvantages of the prior art by proposing in particular a dry manufacturing process for electrodes for battery cells, the process making it possible to reduce the cost of manufacturing the electrodes and to limit material losses.

[0015] Another problem addressed by the invention is to improve the individual alignments of the active material strips on the primary coatings of the current collector strip.

[0016] Finally, another problem addressed by the invention is to guarantee the homogeneity between each electrode produced.

[0017] To this end, according to a first aspect of the invention, a dry manufacturing process for electrodes for battery cells is proposed, the manufacturing process being characterized in that it comprises at least: • (i) a step of cutting the lateral edges of an active material film electrode so as to obtain a pre-cut film of predetermined width measured between its lateral edges; • (ii) a step of cutting the pre-cut film of active electrode material so as to divide the pre-cut film into a plurality of cut strips of active electrode material, each of said cut strips of active electrode material being configured to equip at least one electrode, the predetermined width of the pre-cut film being equal to the sum of the widths of each of the strips cut in the pre-cut film; • (iii) a step of rolling at least one cut strip of active electrode material from the plurality of cut strips on at least one face of a current collector strip, to form a laminated electrode strip.

[0018] 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.

[0019] 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.

[0020] Furthermore, the term "lateral edge" refers to a lateral end portion of the electrode active material film that is bonded to the electrode active material film on only one side. In this sense, after step (i) of cutting the lateral edges of the active material film, no further step of cutting intermediate strips of electrode active material involving the removal of material from the electrode active material film is necessary to obtain the plurality of cut strips of electrode active material.

[0021] In particular, the lateral edges of the active material film of electrodes have a width of less than 20 mm, preferably less than 12 mm, for example a maximum width of 10 mm.

[0022] Such an invention therefore has the technical advantage of reducing the amount of electrode active material film cut and removed from the electrode active material film during the cutting step (i). Indeed, by forming a single electrode active material film, there are only two lateral edges to cut, which reduces the amount of electrode active material to be recycled or discarded and the costs associated with these operations.

[0023] According to the invention, the width of the pre-cut film of active electrode material is equal to the sum of the widths of the strips of the plurality of cut strips of active electrode material, so that the entire width of said pre-cut film is used to manufacture the plurality of cut strips, which further reduces the quantities of active material to be recycled or discarded.

[0024] In practice, the pre-cut film presents: • a width less than or equal to 2m, preferably less than or equal to 1.6m, for example equal to 1m; and / or • a thickness less than or equal to 300pm, preferably less than or equal to 150pm, for example equal to 100pm.

[0025] The cut strip of active electrode material has a width of less than 500 mm. Generally, each of the cut strips has the same width. Furthermore, and generally, the cut strips of active electrode material each have a width greater than or equal to 50 mm, preferably greater than or equal to 80 mm and / or less than or equal to 300 mm, preferably less than or equal to 200 mm, for example equal to 150 mm.

[0026] According to one embodiment, the cuts made in the cutting steps (i) and (ii) are along a so-called longitudinal direction of the film, that is to say in the direction of movement of the film.

[0027] According to a preferred embodiment, step (iii) of the manufacturing process allows the plurality of cut strips on both sides of the current-collecting strip to be laminated, that is, the plurality of laminated strips to be pressed against the current-collecting strip so as to bond them together to form the laminated electrode strip. Thus, after step (iii) of the process, the laminated strip comprises the plurality of cut strips of active electrode material pressed against the current-collecting strip and separated laterally from each other by a predetermined distance.

[0028] According to one embodiment, the current collector strip is for example an aluminum strip or a copper strip, preferably having a length equal to the length of the plurality of cut strips of active electrode material and a width greater than or equal to, preferably strictly greater than, the width of the pre-cut film of active electrode material.

[0029] In practical terms, the current collector strip has: • a width less than or equal to 2.2m, preferably less than or equal to 1.8m, for example equal to 1.2m; and / or • a thickness less than or equal to 15 µm, preferably less than or equal to 12 µm, and preferably less than or equal to 1 µm. This thickness can be adapted according to the material of the strip. A thickness less than or equal to 15 µm is preferred for aluminum and 1 µm for copper, preferably less than or equal to 12 µm for aluminum and 8 µm for copper, for example, 1 µm for aluminum and 6 µm for copper.

[0030] According to one embodiment, a plurality of primary coatings are formed on the current-collecting strip to facilitate the adhesion of the cut strips to the current-collecting strip. These primary coatings are applied to coating areas corresponding to the areas intended to be covered by the cut strips. In this way, the laminated electrode strip is obtained precisely and in a controlled manner.

[0031] According to one embodiment, the cutting steps (i) and (ii) are carried out successively. Advantageously, to accelerate the manufacturing process, the cutting steps (i) and (ii) are carried out simultaneously.

[0032] According to one embodiment, the process includes, upstream of the cutting steps (i) and (ii), a preliminary step of calendering an active electrode material powder, to obtain the active electrode material film.

[0033] The term "electrode active material powder" means a mixture of electrode active material particles and binder material particles, the binder material promoting the cohesion of said dry powder.

[0034] The calendering step allows the dry powder to be compressed and compacted to obtain a film of active electrode material having a precise and controlled thickness and density, which facilitates the execution of the process and makes it possible to obtain the desired characteristics for the cell electrodes.

[0035] According to one embodiment, the process includes, subsequent to the rolling step (iii), a further step of cutting the rolled electrode strip so as to obtain a plurality of electrodes.

[0036] According to one embodiment, the laminated electrode strip is cut along a longitudinal direction and along a transverse direction perpendicular to the transverse direction, so as to form a plurality of electrodes or unit electrodes. The electrodes thus obtained have a length less than or equal to 300 mm, preferably less than or equal to 150 mm, and / or a width less than or equal to 700 mm, preferably less than or equal to 200 mm.

[0037] According to one embodiment, the cutting step (ii) of the pre-cut film of active electrode material is carried out in a first piece of equipment and the rolling step (iii) is carried out in a second piece of equipment, separate from the first piece of equipment.

[0038] The use of a first and a second distinct and separate piece of equipment to carry out steps (ii) and (iii) of the process respectively allows the plurality of cut strips to be positioned precisely before laminating them onto the current collector strip.

[0039] In particular, the process includes, prior to the rolling step (iii) and subsequent to the cutting step (ii), a step of storing the plurality of cut strips on a storage system of the first piece of equipment, the storage system preferably comprising a plurality of winding axes.

[0040] According to one embodiment, the storage system of the first piece of equipment comprises a plurality of winding shafts for retrieving, winding, and temporarily storing the plurality of cut strips of active electrode material pending their use in step (iii) of the rolling process. In particular, the storage system may comprise a plurality of winding rollers installed on the plurality of winding shafts and supporting the windings of the plurality of cut strips.

[0041] Preferably, there are as many strips of the plurality of cut strips as there are winding rollers and winding shafts, so that each cut strip is wound around a winding roller.

[0042] More particularly, the process includes, prior to the rolling step (iii) and subsequent to the storage step, a step of moving the plurality of cut strips of active electrode material from the storage system of the first piece of equipment to a destocking system of the second piece of equipment, in which the cut strips are preferably at least spaced two by two.

[0043] The unstorage system of the second piece of equipment includes a plurality of unwinding axes allowing the plurality of cut strips of active electrode material to be unspooled while awaiting their use in the rolling step (iii) of the process.

[0044] According to one embodiment, there are as many cut strips wound around winding rollers as there are unwinding axes of the unwinding system. Thus, each winding roller supporting a cut strip is moved from a winding axis to an unwinding axis to form an unwinding roller of the unwinding system.

[0045] According to one embodiment, the unwinding axes are spaced by a longitudinal spacing, that is to say measured along the width of the second piece of equipment, predetermined and regular, so that the cut strips enter the laminating plant with a regular spacing between them two by two.

[0046] The storage and handling steps for the plurality of cut strips allow the first and second pieces of equipment to be used independently of each other. Thus, the cut strips produced by the first piece of equipment can be stored for an extended period before being used by the second piece of equipment, without hindering the operation of either. This also allows for intermediate quality control and makes it easy to reject and recycle the strips cut by the first piece of equipment if, for example, characteristics such as thickness or density are not compliant, or if contamination is detected. This recycling of active material strips is much easier than recycling laminated electrode strips, which also contain current-collecting aluminum or copper strips bonded to the active material.

[0047] Such a configuration also allows for precise and optimized parameterization of both the first and second equipment.

[0048] According to another aspect of the invention, it relates to a set of equipment configured to implement the manufacturing process as described above.

[0049] In particular, such a set of equipment is remarkable in that the preliminary calendering stage is implemented by a calendering installation of the first piece of equipment, the calendering installation comprising at least a first calendering roller and a second calendering roller having opposite directions of rotation and differential speeds.

[0050] Advantageously, the calendering installation comprises more than two calendering rollers, for example four rollers having opposite directions of rotation in pairs, so as to precisely control the thickness of the electrode active material film by its passage between a plurality of calendering rollers.

[0051] According to one embodiment, the calendering rollers of the calendering installation have a shorter length than the length of calendering rollers known from the prior art, which reduces the amplitude of roller bending when in use.

[0052] According to one embodiment, the calendering installation includes a discharge hopper for the active electrode material powder, allowing the powder to be discharged into at least one first opening formed between the first calendering roller and the second calendering roller.

[0053] The discharge hopper can be a static hopper or an oscillating hopper. Preferably, the discharge hopper is automated so as to discharge the powder regularly and consistently into the first opening formed between The first and second adjacent calendering rollers. In addition, the calendering installation may include a second opening formed between the second and a third adjacent calendering roller, this second opening allowing for further refinement of the electrode active material film to obtain a film with the desired properties. The calendering installation may also include a third opening formed between the third and a fourth adjacent calendering roller, this third opening allowing for further refinement of the electrode active material film.

[0054] The cutting steps (i) and (ii) are carried out by a cutting installation of the first piece of equipment, the cutting installation comprising at least cutting means.

[0055] According to one embodiment, the cutting means comprise a plurality of blades, or any other means for cutting the film of active electrode material, for example laser knives.

[0056] The rolling step (iii) is carried out by a rolling installation of the second piece of equipment, the rolling installation comprising at least a first rolling roll and a second rolling roll having opposite directions of rotation and identical speeds.

[0057] According to one embodiment, the rolling mill comprises a gap formed between the first and second rolling rolls. Preferably, the rolling mill comprises means for conveying the current-carrying strip into the gap in the mill. Advantageously, the rolling mill is configured to perform vertical rolling, that is, the strip flows locally vertically through the gap formed between the first and second rolling rolls.

[0058] According to one embodiment, the equipment set includes means for controlling the rotation speed of the calendering installation and the rolling installation, the control means being configured so that the rotation speed of the first and second rolling rollers is greater than the rotation speed of the first and second calendering rollers.

[0059] A higher rotation speed for the rolling mill than for the calendering mill allows for cost optimization with a reduced number of rolling equipment compared to the number of calendering equipment.

[0060] Furthermore, the use of means for controlling the rotation speed makes it possible to automate and synchronize the calendering and rolling installations for an assembly line execution of the manufacturing process.

[0061] According to one embodiment, • the first roll of the cutting installation allows the pre-cut film of active electrode material to be recovered; • the cutting means of the cutting installation make it possible to carry out steps (i) and (ii) of the manufacturing process, so as to obtain the plurality of cut strips of active electrode material; • The second roller of the cutting installation allows for the recovery of a portion of the plurality of cut strips of active electrode material, each strip of the plurality of strips being positioned on an inlet path of the second roller. Brief description of the figures

[0062] Other features and advantages of the invention will become apparent from the following description, with reference to the accompanying figures, which illustrate: • [Fig-1]: an isometric view of a first piece of equipment in a set of equipment for implementing a first part of a dry manufacturing process for electrodes for battery cells, according to an embodiment of the invention; • [Fig.2]: an isometric view repeating [Fig.1] but from a different angle; • [Fig. 3]: a close-up isometric view showing a detail of the first equipment of the [Fig.1]; • [Fig.4]: a schematic isometric view of a second piece of equipment in the set of equipment to implement a second part of the dry manufacturing process of electrodes, according to the same embodiment; • [Fig.5]: a front view showing a detail of the second piece of equipment according to this embodiment; • [Fig.6]: a schematic representation of a third part of the dry manufacturing process of electrodes, according to this embodiment.

[0063] For clarity, identical or similar elements are identified by identical reference signs throughout the figures.

[0064] In the description and claims, to clarify the description and claims, the terminology longitudinal, transverse and vertical will be adopted without limitation with reference to the trihedron X, Y, Z indicated in the figures. Detailed description of an implementation method

[0065] Figures 1 to 3 illustrate a first piece of equipment 10 of a set of equipment, the first piece of equipment 10 enabling the implementation of a first part of a dry manufacturing process of electrodes for a battery cell.

[0066] According to this first embodiment of the invention, the first equipment 10 mainly comprises a calendering installation 10 0, a cutting installation 2 0 0, and a storage system 300 shown in [Fig.1].

[0067] In particular, the calendering installation 100 includes a discharge hopper (not shown), a first calendering roller 101 and a second calendering roller 102.

[0068] The first and second calendering rollers 101,102 are cylinders comprising respectively a first axis of rotation and a second axis of rotation, the first and second axes of rotation extending along a longitudinal direction X of the first equipment 10 and being parallel to each other, so that the first and second rollers 101,102 extend parallel along the longitudinal direction X of the first equipment 10.

[0069] The first and second calendering rollers 101, 102 have opposite directions of rotation. The calendering installation 100 further includes control means (not shown) for controlling the rotational speed of the first and second calendering rollers 101, 102. The first and second calendering rollers 101, 102 rotate at differential speeds around their first and second axes of rotation, respectively.

[0070] Furthermore, the calendering installation 100 includes a first opening 103 formed between the first roll 101 and the second roll 102 of the calendering unit. Preferably, the first opening 103 corresponds to the smallest distance between the first roll 101 and the second roll 102, and is adjustable. As shown in Figures 1 to 3, the width of the first opening 103 is measured transversely, that is, along the transverse direction Y of the equipment 10, but it is understood that this width can be measured vertically or longitudinally depending on the arrangement of the first equipment 10.More specifically, the translation of the first calendering roller 101 along the transverse axis of the equipment 10 is blocked, and the second calendering roller 102 is movable along the transverse axis of the equipment 10, so as to allow an operator to adjust the width of the first opening by translation of the second calendering roller 102 relative to the first calendering roller 101. In practice, for satisfactory operation of the calendering installation 100, the width of the first opening 103 is less than or equal to 1 mm, preferably less than or equal to 0.5 mm, for example equal to 0.3 mm.

[0071] The calendering installation 100 as described above makes it possible to carry out a preliminary calendering step of a powder 40 of electrode active material, this step making it possible to obtain a film 50 of electrode active material whose thickness and density depend on the distance (i.e., the width of the first opening) 103) and the differential speed between the calendering rollers 101, 102, The implementation of this preliminary step of the manufacturing process, according to the first embodiment of the invention, is described below.

[0072] The active material powder 40 is poured by gravity into the discharge hopper of the calendering installation 100. Preferably, the active material powder 40 comprises a mixture of electrode active material particles and binder material particles.

[0073] The discharge hopper is a fixed hopper which has a funnel shape and opens into the first opening 103 of the calendering installation 100. According to another embodiment of the invention, the discharge hopper can be an oscillating hopper, which makes it possible to guarantee a homogeneous distribution of the powder 40 of active material in the first opening 103.

[0074] By passing through the first opening 103, the powder 40 of active electrode material is compressed and sheared by the rotation in opposite directions and at different speeds of the first and second calendering rollers 101,102, which makes it possible to produce the film 50 of active electrode material.

[0075] The film 50 of electrode active material, after passing through the first opening 103, has so-called "rough" dimensions, that is, non-final dimensions. In particular, the film 50 has irregular lateral edges 51, that is, uneven lateral edges 51, as illustrated in [Fig. 3]. Consequently, the width of the film 50 of electrode active material, measured longitudinally between its lateral edges 51, is not constant along the film 50.

[0076] Upon exiting the first opening 103, the film 50 of active electrode material adheres to the second calendering roller 102. In particular, the differential speed applied between the first and second calendering rollers 101, 102—here, a higher rotational speed of the second calendering roller 102 compared to the first calendering roller 101—allows the 50 of active electrode material to adhere to the faster of the two rollers. The second calendering roller 102 then conveys the film 50 of active electrode material by rotation into the cutting unit 200. The unit 200 comprises a first "cutting" roller 201, a second "separating" roller 202, and cutting means 205.

[0077] The first and second rollers 201, 202 have the shape of cylinders which have axes of rotation parallel to the axes of rotation of the first and second calendering rollers 101, 102. The cutting installation 200 also includes means for controlling the rotation of the first and second rollers 201, 202, which allow the rotation speed of the cutting installation 200 to be adjusted in particular according to the rotation speed of the calendering installation 100.

[0078] Furthermore, the second calendering roller 102 of the calendering unit 100 and the first cutting roller 201 of the cutting unit 200 are spaced apart by a distance forming a second opening 203 between the calendering unit 100 and the cutting unit 200. According to this embodiment, the width of the second opening 203 is adjustable and measured transversely. In particular, to allow modification of the width of the second opening 203, it could be provided, for example, that the translation of the first cutting roller 201 of the cutting unit 200 along the transverse axis of the equipment 10 is fixed, and the translation of the second calendering roller 102 of the calendering unit 100 is free to move along this same transverse axis.However, the modification of the width of the second opening 203 must be compatible with the modification of the width of the first opening 103: in this case, this modification of the width can be made by translating the first calendering roller 101 relative to the second calendering roller 102. Naturally, several possible configurations exist. In particular, only one of the rollers, among the calendering rollers 101, 102 and the cutting rollers 201 and separating roller 202, will be chosen to be fixed, and the other rollers to be mobile relative to the fixed roller relative to the installation. Here, it is preferable to have the cutting roller 201 fixed, and the other rollers mobile, given the absence of transverse alignment between the separating roller 202 and the three other calendering rollers 101, 102 and cutting roller 201.

[0079] Preferably, to reduce and control the thickness of the electrode active material film 50, the second aperture 203 is narrower than the width of the first aperture 103. Thus, the first aperture 103 allows the dimensions, in particular a first thickness, of the electrode active material film 50 to be determined, and the second aperture 203 allows the thickness and density of the film 50 to be adjusted to achieve one of the predetermined characteristics of the electrode active material film 50. In practice, the width of the second aperture 203 is less than or equal to 0.8 mm, preferably less than or equal to 0.4 mm, for example, equal to 0.1 mm.

[0080] After the passage of the film 50 of active electrode material through the second opening 203, the manufacturing process comprises: • a cutting step (i) of the lateral edges 51 of the film 50 of active electrode material so as to obtain a pre-cut film 60 of predetermined width measured between its lateral edges 51 (see the [Fig.3] of detail); • a cutting step (ii) of the pre-cut film 60 of electrode active material so as to divide the pre-cut film 60 into a plurality of cut strips 70 of active electrode material, each of said cut strips 70 of active electrode material being configured to equip at least one electrode 90, here two electrodes 90, the predetermined width of the pre-cut film 60 being equal to the sum of the widths of each of the cut strips 70 in the pre-cut film 60; the cutting steps (i) and (ii) being carried out by the cutting means 205 of the cutting installation 200.

[0081] According to the first embodiment of the invention, the cutting means 205 comprise a plurality of blades 206 for cutting the film 50 of active electrode material. In particular, the blades of the plurality of blades 206 are located vertically above the first cutting roller 201 of the cutting unit 200, such that at least part, preferably half, of the plurality of cut strips 70 is recovered by the second roller 202 of the cutting unit 200. This is achieved by the fact that the second roller 202 of the cutting unit 200, referred to as the "separation roller" 202, has a speed strictly, but very slightly, higher than that of the first roller 201 of the cutting unit 200, referred to as the cutting roller 201, and a non-perfectly cylindrical shape which allows it to grasp every other strip upon contact.

[0082] The blades of the plurality of blades 206 of the cutting unit 200 are spaced equidistant along an axis parallel to the longitudinal axis X of the equipment 10, so as to obtain a plurality of cut strips 70 of active material of equal widths. In particular, as illustrated in Figures 2 and 3, the plurality of blades 206 comprises at least two end blades 208 that cut the lateral edges 51 of the film 50 of electrode active material to obtain the pre-cut film 60 of predetermined dimensions, in particular of predetermined width, and central blades 209 that cut said pre-cut film 60 into the plurality of cut strips 70 of electrode active material. Thus, only the lateral edges 51 are removed from the film 50 of electrode active material, thereby reducing losses of electrode active material.Advantageously, the side edges 51 are recycled and reused in other production batches.

[0083] Preferably, during the execution of the process, the plurality of blades 206 is supported by a frame (not shown) and is movable relative to the frame by means of pressure which allows controlled pressure to be applied by the rotating blades to an outer surface of the first cutting roller 201 of the cutting installation 200. According to one embodiment, the longitudinal spacing between the blades of the plurality of blades 206 is adjustable, which allows the installation to be adapted cutting 200 to 50 films of active electrode material of variable dimensions.

[0084] It is understood that the cutting means 205 may include any other tool or set of tools for cutting the film 50 of active electrode material.

[0085] To carry out the cutting steps (i) and (ii) of the manufacturing process, the film 50 of active electrode material, exiting the first opening 103, is rotated by the second calendering roller 102 until it reaches the second opening 203, where it is compressed and refined. The thickness and density of the film 50 of active electrode material can thus be adjusted. Next, the film 50 is rotated by the first cutting roller 201 and is cut by the plurality of blades 206. According to the first embodiment of the invention, as illustrated in Figures 1 to 3, the cutting step (i) of the lateral edges 51 of the film 50 is carried out simultaneously with the cutting step (ii) of the pre-cut film 60 of active electrode material into a plurality of cut strips 70.Performing the cutting steps (i) and (ii) of the process simultaneously reduces the process execution time without increasing the technical complexity or manufacturing costs. According to the first embodiment of the invention, the cutting means 205 form four cut strips 70.

[0086] The plurality of cut strips 70 is then conveyed to the storage system 300 of the first piece of equipment 10. The storage system 300 of the first piece of equipment 10 comprises a plurality of winding axes 310, the axes being capable of rotation with a predetermined rotational speed and strip tension. According to the first embodiment, illustrated in Figures 1 and 2, the plurality of winding axes 310 comprises a first and a second upper winding axis 312, 314 and a first and a second lower winding axis 311, 313.

[0087] More specifically, the first and second upper winding shafts 312, 314 and the lower shafts 311, 313 are rotationally movable shafts connected to a frame of the storage system 300. A winding roller (not shown) can be installed on each winding shaft, around which at least one die-cut strip 70 is wound to form a winding. Thus, once a die-cut strip 70 is wound around the winding roller, said roller supporting the winding of the strip 70 can be removed from the winding shaft and replaced by a new winding roller.

[0088] The strips 70 of the plurality of strips 70 are conveyed to the storage system 300 via the second separation roller 202 and the first cutting roller 201. In particular, after the cutting steps (i) and (ii), a The first half of the plurality of strips 70 adheres to the second separating roller 202 and is retrieved by the winding rollers of the first and second upper winding axes 312, 314, and a second half of the plurality of strips 70 adheres to the first cutting roller 201 and is retrieved by the winding rollers of the first and second lower winding axes 311, 313 of the storage system 300. The strips 70 are then wound around the winding rollers of the first and second lower winding axes 311, 313 and upper 312, 314 to form windings. This distinction or separation of the strips 70 towards one path or another depending on their adhesion to the first cutting roller 201 or second separating roller 202 is carried out by a particular configuration of the cutting rollers 201 and separating rollers 202 themselves.In particular, the separation roller 202 is axisymmetric but not perfectly cylindrical: said separation roller 202 has raised edges on the strips it is meant to grip. Furthermore, at a slightly higher speed than the first cutting roller 201, the strips 70 that are touched or brought into contact by these raised edges will adhere to the separation roller 202.

[0089] Preferably, the strips 70 of the plurality of strips 70 are alternately led to the first cutting roller 201 and the second separating roller 202. Thus, for each pair of adjacent cut strips 70, a first strip 70 of the pair of strips 70 passes through the first cutting roller 201 to be wound around a winding roller of one of the lower winding axes 311, 313, and a second strip 70 of the pair of strips 70 passes through the second separating roller 202 to be wound around a winding roller of one of the upper winding axes 312, 314.

[0090] According to the first embodiment of the invention, the second separation roller 202 is located vertically above the first cutting roller 201.

[0091] Furthermore, the second separation roll 202 includes a plurality of raised edges 210. These raised edges facilitate in particular the adhesion of the second half of the plurality of cut strips 70 onto the second separation roll 202.

[0092] The first and second upper winding axes 312, 314 and the lower 311, 313 are located at a distance from the first cutting roller 201 and the second separating roller 202. In particular: • The first and second upper winding shafts 312, 314 are located vertically above the second separation roller 202, the first roller installed on the first upper winding shaft 312 being vertically above the second roller installed on the second upper winding axis 314; • the first and second lower winding axes 311, 313 are located vertically below the first cutting roller 201, the first roller installed on the first lower winding axis 311 being vertically below the second roller installed on the second lower winding axis 313.

[0093] Thus, by rotating and tensioning the strips of the plurality of winding axes 310, the strips 70 of the plurality of cut strips 70 which come from the first cutting roller 201 and the second separating roller 202 wind around the winding rollers of the plurality of winding axes 310, each cut strip 70 winds around a winding roller of a winding axis 310, and are temporarily stored.

[0094] Figures 4 and 5 illustrate a second piece of equipment 20 of a set of equipment, the second piece of equipment 20 enabling the implementation of a second part of the dry manufacturing process of electrodes 90 for a battery cell.

[0095] The second piece of equipment 20 includes a stockpiling system 400 and a rolling installation 500.

[0096] The unwinding system 400 comprises a plurality of unwinding shafts 410 capable of rotation at a predetermined speed and web tension. The plurality of unwinding shafts 410 is mounted around a frame of the unwinding system 400. Furthermore, an unwinding roller can be installed on each shaft of the plurality of unwinding shafts 410 for unwinding a coil of a cut web 70.

[0097] It should be noted that the schematic view of [Fig.4] is simplified. Indeed, since the rolling of the current collector is carried out on both sides of the strip, and since a first part of the equipment illustrated here only produces material for one side of a given strip, the unwinding system 400 actually comprises twice as many axes in a second part of the equipment in [Fig.4], behind each reel there is actually another reel so as to have eight reels in total or unwinding axes.

[0098] According to the first embodiment of the invention, the unwinding system 400 comprises four pairs of two unwinding shafts, of which only two pairs 411, 411' and 413, 413' are shown in [Fig. 4]. For each pair of shafts, a first shaft 411, 413 of the pair of shafts 411, 411', 413, 413' is located transversely on a first side of the rolling mill 500 and a second shaft 411', 413' of the pair of shafts 411, 411', 413, 413' is located transversely on a second side of the rolling mill 500. Thus, the unwinding system 400 comprises eight unwinding axes facing each other transversely and in pairs, on either side of the rolling mill 500 and more precisely on either side of a vertical rolling plane located between a first rolling roll 501 and a second rolling roll 502 of the rolling mill 500. In addition, as shown in [Fig.5], to facilitate the arrangement of the unwinding system, the pairs of axes are aligned vertically in pairs.

[0099] Furthermore, the pairs of axes are arranged so as to be distributed equidistantly along the longitudinal axis X of the second equipment 20. This distribution makes it possible to maintain a regular longitudinal spacing between two windings of cut strips 70 positioned on longitudinally adjacent unwinding axes.

[0100] It is agreed that the arrangements of the unwinding system 400 and the rolling installation 500 may vary, without departing from the scope of this application. For example, according to other embodiments, the eight unwinding axes may face each other in pairs vertically or longitudinally, and / or the rolling plane may be transverse or longitudinal.

[0101] The rolling mill 500 comprises a first rolling roller 501 and a second rolling roller 502, the first and second rollers 501, 502 having axes of rotation parallel to the longitudinal axis X of the second piece of equipment 20. The first and second rolling rollers 501, 502 also have opposite directions of rotation. Rotation control means (not shown) control the rotation of the first and second rolling rollers 501, 502, which are synchronous. Furthermore, the first and second rolling rollers 501, 502 are positioned at a distance from each other to form a gap 503 of predetermined width. As illustrated in Figures 4 and 5, the width of the gap 503 is measured transversely.

[0102] In particular, the rolling installation 500 is located vertically, i.e. along a vertical direction Z of the second equipment 20, below the destocking system 400, in this way, on each transverse side of the rolling installation 500, a first and a second unwinding axis 411, 412 are located vertically above a third and a fourth unwinding axis 413, 414, which are themselves located vertically above the first and second rolling rollers 501, 502 of the rolling installation 500.

[0103] The second piece of equipment 20 also includes means (not shown) for conveying a current-collecting strip 75 into the gap 503 of the rolling installation 500, the strip 75 having a width, measured longitudinally, greater than the sum of the widths of each of the strips cut 70 in the pre-cut film 60.

[0104] The implementation of a rolling step (iii) successive to the cutting steps (i) and (ii) carried out by the first equipment 10 is described below.

[0105] Once wound around the plurality of winding axes 310, the windings of cut strips 70 and the winding rollers that support them are removed from said winding axes 310 and mounted on the plurality of unwinding axes 410 of the unwinding system 400. In practice, the winding rollers supporting the windings of strips 70 can be retained so as to allow the movement of a given winding roller from the storage system 300 of the first equipment 10 to the unwinding system 400 to become an associated unwinding roller.

[0106] As the current collector strip 75 passes through the gap 503, in the direction indicated by the arrows in [Fig.4], the unwinding axes 410 gradually unwind so that the cut strips 70 are positioned on the strips with primary coatings on the strip 75. By their rotation in opposite directions, the first and second rolling rollers 501, 502 press each cut strip 70 against the strip 75 and its primary coatings, so as to form a laminated electrode strip 80 comprising the strip 75 on which are laminated, on each transverse side, the cut strips 70 of the plurality of strips 70, two adjacent strips 70 being spaced longitudinally by the predetermined spacing e.

[0107] The current-collecting strip 75 is formed from a metal sheet, such as a flexible aluminum or copper sheet, a few microns thick. Where the active material is to adhere, primer coatings (for example, including a suitable adhesive) have been applied and cured onto the strip. In this way, the current-collecting strip has coated areas which are covered with primer coatings that facilitate the adhesion of the cut strips 70 onto the current-collecting strip 75.

[0108] Figure 6 illustrates the implementation of a subsequent cutting step of the laminated electrode strip 80. The laminated electrode strip 80, which comprises the strips 70 of the plurality of cut strips 70 laminated onto the current collector 75, is cut along a longitudinal direction, shown in dashed lines in Figure 6, so as to obtain a plurality of electrodes 90. In particular, the cutting of the laminated electrode strip 80 is carried out in one or more longitudinal and transverse cutting steps and by cutting means, for example, blades. The electrodes 90 of the plurality of electrodes 90 thus obtained have standardized dimensions, which allows them to be used in a battery cell manufacturing process.

[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] 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 make such combinations impossible or meaningless.

Claims

Demands

1. A dry manufacturing process for electrodes (90) for battery cells, the manufacturing process being characterized in that it comprises at least: - (i) a step of cutting lateral edges (51) of a film (50) of electrode active material so as to obtain a pre-cut film (60) of predetermined width measured between its lateral edges (51); - (ii) a step of cutting the pre-cut film (60) of electrode active material so as to divide the pre-cut film (60) into a plurality of cut strips (70) of electrode active material, each of said cut strips (70) of electrode active material being configured to equip at least one electrode (90), the predetermined width of the pre-cut film (60) being equal to the sum of the widths of each of the cut strips (70) in the pre-cut film (60);- (iii) a step of rolling at least one diced strip (70) of electrode active material from the plurality of diced strips (70) onto at least one face of a current collector strip (75), to form a laminated electrode strip (80).;

2. A manufacturing method according to claim 1, characterized in that the cutting steps (i) and (ii) are carried out successively or simultaneously.

3. A manufacturing process according to claim 1 or 2, characterized in that it comprises, upstream of the cutting steps (i) and (ii), a preliminary step of calendering a powder (40) of active electrode material, to obtain the film (50) of active electrode material.

4. A manufacturing method according to any one of the preceding claims, characterized in that it comprises, subsequent to the rolling step (iii), a further step of cutting the rolled electrode strip (80) so as to obtain a plurality of electrodes (90).

5. A manufacturing method according to any one of the preceding claims, characterized in that the cutting step (ii) of the pre-cut film (60) of electrode active material is carried out in a first equipment (10) and in that the rolling step (iii) is carried out in a second piece of equipment (20), separate from the first piece of equipment (10).

6. A manufacturing method according to the preceding claim, characterized in that it comprises, prior to the rolling step (iii) and subsequent to the cutting step (ii), a step of storing the plurality of cut strips (70) on a storage system (300) of the first equipment (10), the storage system (300) preferably comprising a plurality of winding axes (310).

7. A manufacturing method according to claim 6, characterized in that it comprises, prior to the rolling step (iii) and subsequent to the storage step, a step of moving the plurality of cut strips (70) of active electrode material from the storage system (300) of the first piece of equipment (10) to a destocking system (400) of the second piece of equipment (20), in which the cut strips (70) are preferably at least spaced two by two.

8. Set of equipment configured to implement the manufacturing process according to any one of the preceding claims.

9. Equipment set configured to implement the manufacturing process according to any one of the preceding claims in combination with claim 8, the equipment set being characterized in that: - the preliminary calendering step is implemented by a calendering installation (100) of the first piece of equipment (10), the calendering installation (100) comprising at least a first calendering roller (101) and a second calendering roller (102) having opposite directions of rotation and differential speeds; and - the cutting steps (i) and (ii) are carried out by a cutting unit (200) of the first piece of equipment (10), the cutting unit (200) comprising at least cutting means (205), and - the rolling step (iii) is carried out by a rolling unit (500) of the second piece of equipment (20), the rolling unit (500) comprising at least a first rolling roller (501) and a second rolling roller (502) having opposite directions of rotation and identical speeds.

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