Method of producing an electrode for a battery cell

Abstract

The invention relates to an apparatus for production of an electrode for a battery cell, wherein the electrode has a current collector coated on both sides with a coating of a material mixture composed of an active material and a binder, wherein the current collector has an uncoated region, wherein the apparatus has: (i) a first compression device through which the electrode can be conducted in a conveying direction and at the same time compressed, (ii) a heating device for irradiating the electrode with thermal energy, where the heating device is disposed upstream or downstream of the first compression device in relation to the conveying direction, (iii) wherein the heating device has a first part-element and a second part-element, wherein the first part-element is positioned at a first distance from one of the coatings, and the second part-element is positioned at a second distance from the uncoated region of the current collector; (iv) wherein the first distance and the second distance are essentially the same.

Description

[0001] DEVICE FOR PRODUCING AN ELECTRODE FOR A BATTERY CELL

[0002] The present invention relates to a device for producing an electrode for a battery cell, in particular for a lithium-ion battery cell, as well as to an electrode and a battery cell.

[0003] In the field of energy storage cells, especially battery cells, especially lithium-ion battery cells, cylindrical, prismatic, and pouch-shaped battery cells are the most common. Battery cells for storing electrical energy play a central role in the field of electromobility, both in purely electric vehicles and in hybrid vehicles. Cylindrical lithium-ion battery cells can have an electrode winding in which the electrodes, including the separator, are spirally wound around a winding core in the sequence separator-anode-separator-cathode.

[0004] The electrode can have a current collector on which a mixture of active material, binder and conductive additives has been applied, in particular on both sides.

[0005] Calendering is a well-known process in the production of electrodes. This involves subjecting the electrodes to high mechanical stress to achieve a high mass density, particularly in the active material. The electrodes are passed between two rollers, which exert mechanical pressure on the electrode, causing the electrode to compress as it passes through, thus increasing its mass density. A higher mass density of electrodes typically enables a higher energy density of a battery cell in which these electrodes are used.

[0006] Due to the high mechanical pressure on the electrode during the compaction process, mechanical stresses often build up within the electrode, which can lead to deformation of the electrode. This is detrimental to further processing, such as further compaction or subsequent winding of the electrode onto a roll. In particular, a deformed area of ​​the electrode can negatively impact this further manufacturing process or even make it impossible. To reduce or relieve these stresses, heat can be applied to the electrode. In this case, it is advantageous to apply heat as evenly as possible to the affected areas of the electrode in order to achieve the most homogeneous stress relief possible.

[0007] The present invention is based on the object of enabling an improved homogeneous heat supply to an electrode during the manufacture of the electrode.

[0008] This object is achieved according to the teaching of the independent claims. Various embodiments and developments of the present invention are the subject of the dependent claims.

[0009] A first aspect of the solution relates to a device for producing an electrode for a battery cell, wherein the electrode has a current collector coated on both sides with a coating of a material mixture of an active material and a binder, wherein the current collector has an uncoated region, wherein the device comprises: (i) a first compaction device through which the electrode can be passed in a conveying direction and thereby compacted, (ii) a heating device for irradiating the electrode with thermal energy, wherein the heating device is arranged upstream or downstream of the first compaction device with respect to the conveying direction, (iii) wherein the heating device has a first sub-element and a second sub-element, wherein the first sub-element is arranged at a first distance from one of the coatings,and the second sub-element is arranged at a second distance from the uncoated region of the current collector; (iv) wherein the first distance and the second distance are substantially equal.

[0010] The terms "comprises," "includes," "has," "has," "having," or any other variation thereof, as used herein, 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. Further, unless expressly 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 present) and B is false (or absent), A is false (or absent) and B is true (or present), and both A and B are true (or present).

[0011] The terms "a" or "an" as used herein are defined as "one or more." The terms "another" and "another," and any other variations thereof, are defined as "at least one other."

[0012] The term "plurality" as used here is to be understood as meaning "two or more".

[0013] The term “configured” or “set up” to fulfil a specific function (and respective variations thereof) as used here means that the corresponding device is already in a design or setting in which it can carry out the function or is at least adjustable – i.e. configurable – so that it can carry out the function after being set accordingly. The configuration can be carried out, for example, by appropriately setting parameters of a process sequence or of switches or the like for activating or deactivating functionalities or settings. In particular, the device can have a plurality of predetermined configurations or operating modes, so that the configuration can be carried out by selecting one of these configurations or operating modes.

[0014] The term "electrode" as used here refers, in particular, to an electrically conductive component comprising a current collector, particularly made of copper or aluminum, and a coating on a top and bottom side of the current collector. The coating is composed, in particular, of an active material, a binder, and additives or conductive additives.

[0015] The term "active material" as used here refers in particular to a material that can be electrochemically active and is suitable for coating electrodes for electrode windings for battery cells, and into which ions, in particular lithium ions, can be embedded. The active material for the cathode can comprise, in particular, NMC, NCA, NCMA, LCO, LFP, LMFP, LMO, LNMO, or another material. The active material for the anode can comprise, in particular, graphite, SiOx, SiC, Si, or another material.

[0016] The term "current conductor" as used here refers in particular to an element made of a conductive material, especially copper or aluminum. It serves to conduct current between two geometrically separated points.

[0017] The term "binder" as used here refers in particular to an element for binding or adhering the active material to a current collector. The binder can, in particular, comprise PVDF, PTFE, CMC, SBR, LiPAA, or PAA.

[0018] The term “essentially the same” as used here means in particular that two values, in particular distance values, do not differ from each other by more than 10%, in particular not more than 5%.

[0019] The device according to the first aspect makes it possible to achieve improved homogeneity in the irradiation of the electrode with heat. This makes it possible to reduce mechanical stresses within the electrode that were created by mechanical compaction. In particular, mechanical stresses can develop between the coated and the adjacent uncoated region of the current collector, since these regions have different thicknesses and are therefore compacted differently. If the distance between a heating device and the electrode or a coating of the electrode is too small, the irradiation with heat or thermal energy can lead to damage to the electrode. If, on the other hand, the distance between the heating device and the current collector is too large, the irradiation, i.e. its intensity, may be insufficient to achieve a reduction in the mechanical stresses.This can be improved by the present heating device with the first sub-element and the second sub-element, which ultimately have equal distances between the first distance and the uncoated current conductor, on the one hand, and the second distance and the coating, on the other. This is because the equal distances enable comparable irradiation of the uncoated current conductor and the coating, or the current conductor underneath. It can be advantageous if the heating device is arranged upstream of the first compaction device, and thus before the initial compaction of the electrode or an electrode section, since heat-treated electrodes can be deformed more easily.

[0020] Preferred embodiments of the device are described below, which can be combined with each other as well as with the other aspects described, unless this is expressly excluded or is technically impossible.

[0021] In some embodiments, the heating device comprises an electromagnetic induction device, in particular with one or more electrical coils. An electromagnetic induction device is also known as an induction heater. The heat or thermal energy can be supplied to the electrode by means of an electromagnetic interaction between the electrode and the electromagnetic induction device. Electrical energy, in turn, can be supplied to the electromagnetic induction device via an electrical energy source. The generation and supply of heat or thermal energy by means of electromagnetic induction enables high efficiency, whereby the induction heater itself does not heat up directly.

[0022] In some embodiments, the heating device comprises an infrared lamp heater. An infrared lamp heater can heat the ambient air, creating a heated airflow that can be directed to the desired area of ​​the electrode. An infrared lamp heater can be used freestanding, i.e., without direct contact with the electrode.

[0023] In some embodiments, the heating device is formed as a single piece. In particular, the first sub-element and the second sub-element can be integrated into a single component. This has the advantage of a more compact design, which can ultimately save installation space. Furthermore, a simpler arrangement with improved flexibility is possible, since only one component needs to be arranged instead of two sub-elements, and coordination of the two sub-elements with each other can also be eliminated.

[0024] In some embodiments, the heating device has a cross-section that is perpendicular to the conveying orientation of the electrode and is Z-shaped. This allows a first spacing and a second spacing for homogeneous irradiation to be achieved with a relatively simple shape.

[0025] In some embodiments, the device comprises a second compaction device, wherein the heating device is arranged between the first compaction device and the second compaction device. This enables further compaction after the heat supply by the heating device. In particular, compaction can be achieved with lower mechanical stresses because the electrode was heated prior to compaction.

[0026] A second aspect of the solution relates to an electrode produced using the device according to the first aspect, wherein the electrode has a current collector coated on both sides with a coating, wherein the current collector has an uncoated region.

[0027] In some embodiments, a tensile strength distribution can be determined for the uncoated region that has a profile different from a Gaussian curve. In particular, the tensile strength distribution can have more than one local maximum value or a broader maximum than a Gaussian curve.

[0028] A third aspect of the solution relates to an energy storage cell, in particular a battery, in particular a lithium-ion battery, comprising an electrode according to the second aspect.

[0029] A fourth aspect of the solution relates to a motor vehicle with an electric drive or a hybrid drive and an energy storage cell according to the third aspect. The features and advantages explained with regard to the first aspect of the solution also apply accordingly to the other aspects described.

[0030] Further advantages, features and possible applications emerge from the following description of preferred embodiments in conjunction with the figures.

[0031] This shows

[0032] Fig. 1 shows schematically a calendering device with a heating device of a first embodiment in a side view;

[0033] Fig. 2A schematically shows a heating device of the first embodiment in a front view;

[0034] Fig. 2B schematically shows the heating device according to the first embodiment of Fig. 2A in a plan view;

[0035] Fig. 3 schematically shows a heating device according to a second embodiment in a front view; and

[0036] Fig. 4 schematically shows a heating device according to a fourth embodiment in a front view.

[0037] Throughout the figures, the same reference numerals are used for the same or corresponding elements.

[0038] Figure 1 schematically shows a calendering device 100 with a first heating device of a first embodiment in a side view.

[0039] The calendering device 100 has a first compaction device 120 with a first roller 110 and a second roller 115, as well as a second compaction device 140 with a third roller 130 and a fourth roller 135. The four rollers 110, 115, 130, 135 each rotate about an axis parallel to the y-axis of the schematically illustrated coordinate system. The first roller 110 is spaced apart from the second roller 115 in the z-direction. Likewise, the third roller 130 is spaced apart from the fourth roller 135 in the z-direction. The first compaction device 120 is spaced apart from the second compaction device 140 in the x-direction.

[0040] The distances in the z-direction between the first roller 110 and the second roller 115 on the one hand, and between the third roller 130 and the fourth roller 135 on the other hand, are selected such that when an electrode 200 is passed through these spaced rollers in a conveying direction z, a desired compaction of the electrode 200 can be achieved.

[0041] The electrode 200 has a current collector 210, in particular made of copper or aluminum, and a coating 220 on a top side and a bottom side of the current collector 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 collector 210.

[0042] In the present electrode 200, the current collector 210 protrudes beyond the coatings 220 in the y-direction. This is further illustrated in Figures 2A and 2B. During a compaction process by one or both of the compaction devices 120, 140, a different mechanical stress therefore acts on the coated and uncoated regions of the current collector 210.

[0043] Furthermore, the calendering device 100 has a heating device 250 according to a first embodiment, with a first electrical coil 230 and a second electrical coil. The heating device 250 is arranged in the x-direction between the first compacting device 120 and the second compacting device 140. The electrode 200 can be warmed or heated in sections by the heating device 250. Electrical energy is supplied to the first electrical coil 230 and / or the second electrical coil 240 by an electrical energy source (not shown here), whereby heat is supplied to the electrode 200 and the current collector via the electrical coils 230, 240 by means of electrical induction. The first electrical coil 230 is spaced from the second electrical coil 240 in the x-direction, the y-direction, and the z-direction. The spacing in the x-direction and in the z-direction can be seen in Fig. 1. The spacing orDisplacement in the y-direction is illustrated in Figures 2A and 2B, which show the first heater 250 and the electrode 200 according to the first embodiment in a front view and a top view, respectively.

[0044] The rollers 110, 115, 130, 135 each have a cylindrical shape extending in the y-direction and are each driven by an electric motor (not shown here), which can also control the speed of rotation of the rollers 110, 115, 130, 135.

[0045] The present calendering device 100 can be used advantageously if the coated current collector 210, i.e. the electrode 200, is designed as a web material, since this allows the electrode 200 to be effectively conveyed and processed in the roll-to-roll process.

[0046] Likewise, in the calendering device 100, alternatively or cumulatively to the first heating device 250 according to the described first embodiment, a heating device 300, 400 according to one or more of the described further embodiments according to Figures 3 to 5 can be provided.

[0047] Furthermore, the heating device 250, i.e., the first electrical coil 230 and the second electrical coil 240, can also be arranged in the x-direction upstream of the first compression device 120 and / or downstream of the second compression device 140. However, arranging the heating device 250 upstream of the first compression device 120, and thus before the initial compression of the electrode 200 or a portion of the electrode 200, is advantageous because heat-treated electrodes can be deformed more easily.

[0048] Figure 2A schematically shows a front view of a heating device 250 of the first embodiment, comprising the first coil 230 and the second electrical coil 240, and an electrode 200 according to the first embodiment. The spacing or offset of the first coil 230 relative to the second electrical coil 240 in the z-direction and the y-direction is schematically illustrated. Furthermore, the illustration shows that the current collector 210 protrudes beyond the coatings 220 in the y-direction, thereby forming an uncoated region of the current collector 210. During a compaction process by one or both of the compaction devices 120, 140, a different mechanical stress acts on the coated and uncoated regions of the current collector 210.

[0049] It is further shown that the first electrical coil 230 is arranged at a first distance D1 from an uncoated region of the current collector 210, and the second electrical coil 240 is arranged at a second distance D2 from the coating 220 lying above the current collector 210 in the z-direction.

[0050] The first coil 230 and the second electrical coil 240 are arranged such that the first distance D1 and the second distance D2 are substantially equal. This is advantageous for achieving homogeneous heat radiation onto the electrode 200 or onto the illustrated heat-treated region 160. This heat-treated region extends over the uncoated region and partially onto the coated region of the current collector 210. This allows the overall mechanical stresses to be reduced, particularly in a boundary region between the coated and uncoated regions.

[0051] If the distance between an electrical coil and the electrode 200 or the coating is too small, this may result in damage to the electrode 200 due to the irradiation. However, if the distance between an electrical coil and the current collector 210 is too large, the irradiation intensity may be insufficient.

[0052] This is avoided by arranging the first electrical coil 230 and the second electrical coil 240 with the described distances D1, D2.

[0053] In the present illustration, the heat-treated region 165 of the current collector 210 is marked in the y-direction, and the heating device 250 is shown only on one side of the electrode 200. Likewise, a heat-treated region 165, which has an uncoated region, can be formed on the other side of the electrode 200 in the y-direction, and the heating device 250 can also be arranged there alternatively or cumulatively. The same applies to the illustration in the following figures or embodiments.

[0054] Figure 2B schematically shows the heating device 250 according to the first embodiment and the electrode 200 according to the first embodiment in a plan view. This additionally illustrates that the first electrical coil 230 is offset from the second electrical coil 240 in the y-direction and spaced apart in the x-direction.

[0055] Figure 3 schematically shows a heating device 300 according to a second embodiment and an electrode 200 in a front view. According to this embodiment, the heating device 300 is designed as a single piece. Therefore, there is no spacing, particularly not in the x-direction. The distances D1, D2, as described in the first embodiment, are achieved here by a "z-shape" in the cross-section, which is perpendicular to the x-axis, of the heating device 300, which is designed as a single piece.

[0056] Figure 4 schematically shows a heating device 400 according to a third embodiment and a further electrode 450 in a front view. In this embodiment, the further electrode 450 has an uncoated region in a central region in the y-direction, so that a further current collector 460 is coated with a further coating 470 laterally thereto. The heating device 400 has a "T-shape" in cross-section and, according to the present embodiment, is composed of three separate electrical coils. Likewise, the heating device 400 can be formed in one piece as a "T-shaped" coil. A region 170 heat-treated by the heating device 400 extends into a central region in the y-direction and partially on both sides into a coated region.

[0057] While at least one exemplary embodiment has been described above, it should be appreciated that a wide variety of variations exist. It should also be understood that the described exemplary embodiments are only 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 a guide to 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 as defined in the appended claims, as well as their legal equivalents.

[0058] LIST OF REFERENCE SYMBOLS

[0059] 100 calendering device

[0060] 110, 115 First, second roller

[0061] 130, 135 Third, fourth reel

[0062] 120, 140 First, second compression device

[0063] 160, 165, 170 Heat-treated area

[0064] 200 electrodes

[0065] 210 current arresters

[0066] 220 coating

[0067] 230, 240 First, second electrical coil

[0068] 250 Heating device of a first embodiment

[0069] 300 Heating device of a second embodiment

[0070] 400 Heating device of a third embodiment

[0071] 450 Additional electrode

[0072] 460 Additional current collector

[0073] 470 Additional coating

Claims

CLAIMS 1. Device (100) for producing an electrode (200, 450) for a battery cell, wherein the electrode (200, 450) has a current collector (210, 460) which has a coating (220) made of a material mixture of an active material and a binder on both sides, wherein the current collector (210, 460) has an uncoated area, wherein the device comprises: a first compaction device (120) through which the electrode (200, 450) can be passed in a conveying direction (x) and thereby compacted, a heating device (250, 300, 400) for irradiating the electrode (200, 450) with thermal energy, wherein the heating device (250, 450) is arranged upstream or downstream of the first compaction device (110, 115) with respect to the conveying direction (x). is;wherein the heating device (250, 300, 400) comprises a first sub-element (230) and a second sub-element (240), wherein the first sub-element (230) is arranged at a first distance (D1) from one of the coatings (220), and the second sub-element (240) is arranged at a second distance (D2) from the uncoated region of the current collector (210, 460); wherein the first distance (D1) and the second distance (D2) are substantially equal.

2. Device (100) according to claim 1, wherein the heating device comprises an electromagnetic induction device (250, 300, 400).

3. Device (100) according to claim 1 or 2, wherein the heating device comprises an infrared lamp heater (250, 300, 400).

4. Device (100) according to one of the preceding claims, wherein the heating device (250, 300, 400) is formed in one piece.

5. Device (100) according to one of the preceding claims, wherein the heating device (250, 300) has a cross section which is perpendicular to the conveying orientation of the electrode (200, 450) and which is z-shaped.

6. Device (100) according to one of the preceding claims, comprising a second compression device (140), wherein the heating device (250, 300, 400) is arranged between the first compression device (120) and the second compression device (140).

7. An electrode (200, 450) produced using the device according to any one of the preceding claims, wherein the electrode comprises a current collector (210, 460) coated on both sides with a coating (220) made of a material mixture of an active material and a binder, the current collector having an uncoated region.

8. Electrode (200, 450) according to claim 7, wherein a tensile strength distribution can be determined for the uncoated region which has a course different from a Gaussian curve.

9. Energy storage cell comprising an electrode according to claim 7 or 8.

10. Motor vehicle with an electric drive or a hybrid drive and an energy storage cell according to claim 9.

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