DE102023108128A1 - METHOD AND DEVICE FOR SEPARATING AN ACTIVE MATERIAL FROM A CURRENT CONDUCTOR - Google Patents

Abstract

The invention relates to a method, in particular a computer-implemented method, for separating an active material from a current conductor, in particular a current conductor foil, wherein the current conductor has been coated on at least one side with a material mixture of the active material and a binder, with the following automated steps: (i) heating the coated current conductor with a softening temperature of the binder; (ii) mechanically loading the heated coated current conductor, whereby the active material is at least partially broken up, thereby enabling the active material to be separated from the current conductor.

Description

The present invention relates to a method and a device for separating an active material from a current conductor.

In the field of energy storage cells, especially battery cells, especially lithium-ion battery cells, cylindrical, prismatic and pouch-shaped battery cells are known. Battery cells for storing electrical energy play a central role in the field of so-called electromobility, both in vehicles with purely electric drives and in vehicles with hybrid drives. Cylindrical lithium-ion battery cells can have an electrode winding in which the electrodes including the separator are wound spirally around a winding core in the sequence separator-anode-separator-cathode.

The electrode can be formed by a current collector to which a mixture of active material, binder and conductive additives has been applied, in particular on both sides.

During subsequent calendering, the electrode with the applied coating can be conveyed between two rollers, which exert mechanical pressure on the electrode so that it is compacted during conveyance and the mass density of the electrode is increased. A higher mass density of electrodes usually enables a higher energy density of a battery cell in which these electrodes are used.

After the battery cell's service life has expired or if there are rejects during a manufacturing process, it is desirable for economic and ecological reasons to recycle the respective components of the battery cell. This applies not least to the electrodes. For recycling, the materials must be separated, in particular the active material must be separated from the current conductor. Mechanical processes can be used in which the coated current conductor is broken down into small pieces, which are then sorted.

The object of the present disclosure is to enable an improved separation of the active material from a current conductor so that the active material and/or the current conductor can be reused.

This object is achieved according to the teaching of the independent claims. Various embodiments and developments of the invention are the subject of the subclaims.

A first aspect of the solution relates to a method, in particular a computer-implemented method, for separating an active material from a current conductor, in particular a current conductor foil, wherein the current conductor has been coated on at least one side with a material mixture of the active material and a binder, with the following automated steps: (i) heating the coated current conductor with a softening temperature of the binder; (ii) mechanically loading the heated coated current conductor, whereby the active material is at least partially broken up, thereby enabling the active material to be separated from the current conductor.

As used herein, the terms "comprises," "includes," "has," "includes," "comprising," "having," "with," or any other variation thereof are intended to cover non-exclusive inclusion. For example, a method or apparatus that comprises or has a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or that are inherent in such method or apparatus.

Furthermore, unless explicitly stated to the contrary, "or" refers to an inclusive "or" and not an exclusive "or". For example, a condition A or B is satisfied by one of the following conditions: A is true (or exists) and B is false (or absent), A is false (or absent) and B is true (or exists), and both A and B are true (or exists).

As used herein, the terms "a" or "an" are defined to mean "one or more". The terms "another" and "another" and any other variation thereof are defined to mean "at least one other".

The term “plurality” as used here is to be understood as meaning “two or more”.

The term "configured" or "set up" to fulfil a specific function (and respective variations thereof) as used here is to be understood as meaning that the corresponding device is already in a configuration or setting in which it can carry out the function or it is at least adjustable - i.e. configurable - so that it can carry out the function after the corresponding setting. The configuration can be achieved, for example, by setting the parameters of a process sequence or switches or similar for activation or deactivation. activating functionalities or settings. In particular, the device can have several predetermined configurations or operating modes, so that the configuration can be carried out by selecting one of these configurations or operating modes.

The term "active material" as used here refers in particular to a material that can be electrochemically active and that is suitable for coating electrodes for electrode windings for battery cells and in which ions, in particular lithium ions, can be stored. The active material for the cathode can in particular comprise NMC, NCA, NCMA, LCO, LFP, LMFP, LMO, LNMO or another material. The active material for the anode can in particular comprise graphite, SiOx, SiC, Si or another material.

The term "current conductor" as used here refers in particular to an element made of a current-conducting material, in particular copper or aluminum. It is used to conduct current between two geometrically separated points.

The term "binder" as used here refers in particular to an element for binding or adhering the active material to a current conductor. The binder can in particular comprise PVDF, PTFE, CMC, SBR, LiPAA or PAA.

The method according to the first aspect makes it possible to effectively separate an active material from a current conductor. Heating the current conductor coated with the active material to a softening temperature of the binder results in the binding effect of the binder deteriorating. The active material can then be broken by mechanical stress, allowing it to be detached from the current conductor, since the coating itself is brittle and the film is ductile. This means that the active material and the current conductor can each be collected separately and reused.

Preferred embodiments of the method are described below, which can be combined with each other and with the other aspects described as desired, unless this is expressly excluded or is technically impossible.

In some embodiments, the method further comprises: (i) heating at least a first roller to a softening temperature of the binder; (ii) conveying the coated current conductor over the first roller, whereby heating of the coated current conductor occurs through the heated first roller. This allows for effective heating of a longer current conductor path through the first roller. Furthermore, when producing a coated current conductor, calendering can occur using a roller arrangement. This roller arrangement can now be used for the heating step with minor modifications, thereby enabling a cost-effective process.

In some embodiments, the method further comprises: (i) heating a second roller to the softening temperature of the binder, wherein the first roller and the second roller are arranged at a distance substantially parallel to one another with respect to their respective axis of rotation, in particular at a distance substantially corresponding to a thickness of the coated current conductor; (ii) conveying the coated current conductor between the first roller and the second roller, whereby the heating of the coated current conductor takes place through the heated first roller and the heated second roller. This makes it possible to achieve rapid and homogeneous heating of the coated current conductor, since the coated current conductor is heated from two sides during conveyance between the first roller and the second roller. During the present heating, mechanical contact between the coated current conductor and one of the rollers is advantageous in order to transfer the heat effectively by means of thermal conduction. In particular, a distance between the first roller and the second roller can be set, at which a predetermined pressure is exerted by the first and second rollers on the coated current conductor, whereby a tension is introduced into the coating. This allows a subsequent separation of the coating from the current conductor. Accordingly, a roller arrangement intended for calendering can be used for the present heating and can be advantageously adapted with regard to the spacing of the first roller from the second roller.

In some embodiments, the first roller and/or the second roller comprises a heat-conducting material, in particular copper. This enables a particularly good and effective transfer of heat from the first roller and/or the second roller to the coated current conductor.

In some embodiments, heating the coated current conductor to a decomposition temperature of the binder is continued This makes it easier to separate the coating from the current conductor. In addition, subsequent separation of the binder from the active material can be avoided.

In some embodiments, the mechanical loading of the heated coated current conductor is carried out by at least one third roller, on the surface of which elevations, in particular pointed elevations, are formed, wherein the third roller and a fourth roller are arranged spaced apart substantially parallel to one another with respect to their respective axis of rotation, in particular spaced apart by a distance that is less than the thickness of the coated current conductor and greater than the thickness of the uncoated current conductor, wherein the mechanical loading is carried out by the surface with elevations when the heated coated current conductor is conveyed between the third roller and the fourth roller, thereby at least partially breaking the active material. By using at least one roller for the mechanical loading, a continuously coated current conductor, which is rolled up on a roll, for example, can be continuously conveyed. In conjunction with the previous conveying of the coated current conductor by the first roller, it is possible for the next process step of mechanical loading to be applied effectively and continuously to the already heated coated current conductor.

In some embodiments, the first roller and/or the second roller and/or the third roller and/or the fourth roller are driven by a motor, in particular an electric motor, whereby the respective roller rotates about its axis of rotation. By driving at least one of the rollers by a motor, the conveying of the coated current conductor is effectively controlled. In particular, the motor can control a rotational speed and thus the speed of conveying. For effective heat transfer through the first roller and/or the second roller, a comparatively low speed can be advantageous.

A second aspect of the solution relates to a device for separating an active material from a current conductor, wherein the current conductor has been coated on at least one side with a material mixture of the active material and a binder, wherein the device is designed to carry out the method according to one of the preceding claims.

In some embodiments, the apparatus comprises: (i) a first roller and a second roller spaced apart substantially parallel to each other with respect to their respective axes of rotation and adapted to convey a coated current conductor between the first roller and the second roller; (ii) a heating device adapted to heat the first roller and the second roller to a softening temperature of the binder, whereby the coated current conductor is heated to the softening temperature during conveyance between the first roller and the second roller.

In some embodiments, the device comprises a third roller and a fourth roller which are arranged substantially parallel to one another and spaced apart with respect to their respective axes of rotation, wherein at least one of the third roller and the fourth roller has a surface structure with elevations such that, when conveyed between the third roller and the fourth roller, the coated current conductor is mechanically loaded by the surface structure with elevations such that the active material is at least partially broken up and separation of the active material from the current conductor is made possible.

A third aspect of the solution relates to a computer program with instructions which, when executed on a device according to the second aspect, cause the device to carry out the method according to the first aspect

The features and advantages explained with regard to the first aspect of the solution also apply to the other aspects described.

Further advantages, features and possible applications emerge from the following description of preferred embodiments in connection with the figures.

• 1 schematisch ein Flussdiagramm zur Veranschaulichung einer bevorzugten Ausführungsform eines Verfahrens zum Abtrennen eines Aktivmaterials von einem Stromableiter; und
• 2 schematisch eine Vorrichtung gemäß einer Ausführungsform.

This shows

• 1 schematically a flow chart to illustrate a preferred embodiment of a method for separating an active material from a current conductor; and
• 2 schematically shows a device according to an embodiment.

Throughout the figures, the same reference numerals are used for the same or corresponding elements.

In 1 is a schematic flow chart illustrating a preferred embodiment of a method for separating an active material from a current conductor 210, wherein the current conductor 210 has been coated on at least one side with a material mixture of the active material 210 and a binder.

In a first step 110 of the method, the coated current conductor 210 is heated to a softening temperature of the binder. The binder can in particular comprise polyvinylidene fluoride (PVDF), the softening temperature of which is approximately 120°C.

In a further step 120 of the method, the heated coated current conductor 210 is subjected to mechanical stress, whereby the active material is at least partially broken up, thereby enabling the active material to be separated from the current conductor 210.

In 2 a device 200 according to an embodiment is shown schematically.

The device 200 has a housing 230 in which a first roller 250 and a second roller 255 are arranged, and which are arranged opposite one another and spaced apart from one another with respect to their axes of rotation. A heating device 240 is also arranged in the housing 230. The heating device 240 can warm or heat both the first roller 250 and the second roller 255 as well as an interior of the housing 230.

The housing 230 further has an inlet opening and an outlet opening which are at approximately the same height with respect to the plane of the drawing.

During operation, an electrode 205 is conveyed through the inlet opening between the first roller 250 and the second roller 255 in a conveying direction. The conveying direction is shown schematically by the arrow. The electrode 205 has a current conductor 210, in particular made of copper or aluminum, and a coating 220 on an upper side and a lower side of the current conductor 210. The coating 220 is composed of an active material, a binder and additives or conductive additives. The conductive additives can in particular comprise carbon black or carbon fibers. The coating 220 can be applied as a paste to both sides of the current conductor 210.

When the coated current conductor 210 is conveyed between the first roller 250 and the second roller 255, the coatings come into mechanical contact with the first roller 250 and the second roller 255, whereby heat is transferred to the coatings by means of thermal conduction. The heating device 240 is set so that the first roller 250 and the second roller 255 are heated to a softening temperature of the binder. As a result, the coatings are heated to the softening temperature when conveyed between the first roller 250 and the second roller 255. It is therefore advantageous if the first roller 250 and the second roller 255 have a material with good thermal conductivity, such as copper.

Heating the coating 220 reduces the binding effect of the binder.

The binder may comprise polyvinylidene fluoride (PVDF), for which the softening temperature is approximately 120°C and the temperature at which decomposition begins is 350°C. The temperature of the heating device 240 is controlled by a control device integrated in the heating device 240 (not shown here).

The device further comprises a third roller 260 and a fourth roller 265, which are arranged in the conveying direction after the first roller 250 and the second roller 255 and outside the housing 230. The third roller 260 and a fourth roller 265 are arranged opposite one another and spaced apart from one another with respect to their axes of rotation. The third roller 260 and a fourth roller 265 each have a surface structure such that when the coated current conductor 210 is conveyed between the third roller 260 and the fourth roller 265, the surface structure mechanically loads the coated current conductor 210, whereby the heated coatings 220 are broken and can thus be separated from the current conductor 210. In order to improve the breaking of the heated coatings 220, the surface structure has protruding elevations, in particular pointed elevations, for example pyramid-shaped, conical or tooth-shaped elevations. The spacing of the third roller 260 from the fourth roller 265 is advantageously selected such that the elevations reach approximately to the surface of the uncoated current conductor 210 during transport.

By breaking, the active material is broken down into smaller pieces and the current collector 210 into larger pieces. This allows the active material to be easily separated from the electrode material and reused.

The rollers 250, 255, 260, 265 each have a cylindrical shape and are each operated by an electric motor (not shown here), which can also control the speed of rotation of the rollers.

The present device can be used advantageously when the coated current conductor 210 is designed as a web material, since this allows the coated current conductor 210 to be effectively conveyed and processed in the roll-to-roll process.

While at least one exemplary embodiment has been described above, it should be noted that a wide variety of variations thereon exist. It should also be noted that the exemplary embodiments described are merely non-limiting examples and are not intended to limit the scope, applicability, or configuration of the devices and methods described herein. Rather, the foregoing description will provide one skilled in the art with guidance for implementing at least one exemplary embodiment, it being understood that various changes in the operation and arrangement of the elements described in an exemplary embodiment may be made without departing from the subject matter set forth in the appended claims, as well as their legal equivalents.

REFERENCE SYMBOL LIST

100

Flowchart illustrating a preferred embodiment of a method

110

Heating the coated current conductor

120

Mechanical loading of the coated current conductor

200

device

205

electrode

210

current conductor

220

Coating

230

Housing

240

heating device

250, 255

First and second roller

260, 265

third and fourth reels

Claims (11)

Method for separating an active material from a current conductor (210), wherein the current conductor (210) has been coated on at least one side with a material mixture (220) of the active material and a binder, with the following automated steps: Heating the coated current conductor (210) with a softening temperature of the binder; Mechanically loading the heated coated current conductor (210), whereby the active material is at least partially broken up, thereby enabling the active material to be separated from the current conductor (210). procedure according to Claim 1 , further comprising: heating at least a first roller (250) to a softening temperature of the binder; conveying the coated current conductor (210) over the first roller (250), whereby the heating of the coated current conductor (210) occurs by the heated first roller (250). procedure according to claim 2 , further comprising: heating a second roller (255) at the softening temperature of the binder, the first roller (250) and the second roller (255) being arranged spaced apart substantially parallel to one another with respect to their respective axes of rotation; conveying the coated current conductor (210) between the first roller (250) and the second roller (255), whereby heating of the coated current conductor (210) occurs by the heated first roller (250) and the heated second roller (255). procedure according to claim 2 or 3 , wherein the first roller (250) and/or the second roller (255) comprises a heat-conducting material. Method according to one of the preceding claims, wherein the heating of the coated current conductor takes place up to a decomposition temperature of the binder. Method according to one of the preceding claims, wherein the mechanical loading of the heated coated current conductor (210) is carried out by at least one third roller (260) on the surface of which elevations are formed, wherein the third roller (260) and a fourth roller (265) are arranged spaced apart substantially parallel to one another with respect to their respective axis of rotation, wherein the mechanical loading is carried out by the surface with elevations when the heated coated current conductor (210) is conveyed between the third roller (260) and the fourth roller (265), and whereby the active material is at least partially broken. Method according to one of the Claims 2 until 6 , wherein the first roller (250) and/or the second roller (255) and/or the third roller (260) and/or the fourth roller (265) are driven by a motor, whereby a rotation of the respective roller (250, 255, 260, 265) about its axis of rotation. Device for separating an active material from a current conductor, wherein the current conductor has been coated on at least one side with a material mixture of the active material and a binder, wherein the device is adapted to carry out the method according to one of the preceding claims. device according to claim 8 comprising: a first roller (250) and a second roller (255) which are arranged substantially parallel to one another with respect to their respective axes of rotation and are suitable for conveying a coated current conductor (210) between the first roller (255) and the second roller (260); a heating device (240) which is arranged to heat the first roller (250) and the second roller (255) to a softening temperature of the binder, whereby the coated current conductor (210) is heated to the softening temperature during conveyance between the first roller (250) and the second roller (255). device according to claim 8 or 9 comprising a third roller (260) and a fourth roller (265) which are arranged substantially parallel to one another with respect to their respective axes of rotation, wherein at least one of the third roller (260) and the fourth roller (265) has a surface structure with elevations such that when conveyed between the third roller (260) and the fourth roller (265), the coated current conductor (210) is mechanically loaded by the surface structure with elevations such that the active material is at least partially broken up and separation of the active material from the current conductor is made possible. Computer program containing instructions which, when executed on a device according to one of the Claims 8 until 10 cause them to initiate the procedure according to one of the Claims 1 until 7 to execute.

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