METHOD FOR PRODUCING A CATHOD ELECTRODE FOR A BATTERY CELL

Abstract

Method for manufacturing a cathode electrode (20) for a battery cell (10), comprising: Providing a dry powder mixture (130) comprising an active material (62), a conductive additive (64) and a binder (66) to a first extruder; Mixing the active material (62), the conductive additive (64) and the binder (66) in the first extruder (110); Partial fibrillation of the binder (66) in the first extruder (110); Feeding a mixture from the first extruder (110) to a first inlet (144) of a second extruder (120); Supplying a solvent to a second inlet (150) of the second extruder (120); Mixing the active material (62), the conductive additive (64), the binder (66) and the solvent in the second extruder (120); Fibrillation of the binder (66) in the second extruder (120); and Forming an active material layer (24, 160, 250, 352) using an extrusion nozzle (124) located at an outlet of the second extruder (120).

Description

INTRODUCTION

[0001] The present invention relates to a method for producing a cathode electrode for a battery cell. The present disclosure relates to battery cells and, in particular, to a method for producing active material layers and / or electrodes for battery cells using a semi-dry powder.

[0002] The publication DE 10 2022 105 662 A1 describes a process for the continuous production of a battery electrode from an electrode powder mixture.

[0003] Publication US 2008 / 0268334A1 describes a process for producing multilayer laminates of polymeric electrolyte material containing one or more electrode layers.

[0004] Publication WO 2023 / 190 939 A1 describes a process for the production of battery electrodes that enables the continuous generation of an electrode composition.

[0005] Publication EP 4 362 121 A1 describes a method for producing an electrode suspension.

[0006] The publication JP 2005 - 222 772 A describes a method for manufacturing a high-capacity electrode for a lithium-ion secondary battery.

[0007] Electric vehicles (EVs), such as battery electric vehicles (BEVs), hybrid vehicles, and / or fuel cell vehicles, comprise one or more electric motors and a battery system with one or more battery cells, modules, and / or packs. A power control system is used to manage the charging and / or discharging process of the battery system during charging and / or driving.

[0008] Battery cells comprise cathode electrodes, anode electrodes, and separators. The cathode electrodes comprise a layer of cathode active material (comprising cathode active material) arranged on a cathode current collector. The anode electrodes comprise a layer of anode active material (comprising anode active material) arranged on an anode current collector. SUMMARY

[0009] A method according to the invention for producing a cathode electrode of a battery cell comprises supplying a dry powder mixture comprising an active material, a conductive additive and a binder to a first extruder; mixing the active material, the conductive additive and the binder in the first extruder; partially fibrillating the binder in the first extruder; feeding a mixture from the first extruder to a first inlet of a second extruder; feeding a solvent to a second inlet of the second extruder; mixing the active material, the conductive additive, the binder and the solvent in the second extruder; fibrillating the binder in the second extruder; and forming an active material layer using an extrusion die arranged at an outlet of the second extruder.

[0010] In other characteristics, the first temperature of the first extruder is in the range of 19 °C to 70 °C and the second temperature of the second extruder is greater than 70 °C.

[0011] In other respects, the binder is selected from a group consisting of polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), perfluoroalkoxyalkane (PFA), ethylenetetrafluoroethylene (ETFE), polyethylene (PE), and combinations thereof. One particle size of the binder ranges from 1 µm to 1000 µm. Another particle size of the binder ranges from 1 µm to 50 µm.

[0012] In other characteristics, the solvent is selected from a group consisting of alcohols, esters, and combinations thereof. The solvent constitutes 5 to 20 wt% of the mixture. Partial fibrillation of the binder in the first extruder involves fibrillation of the binder in the range of 10% to 40%. Fibrillation of the binder in the second extruder involves fibrillation of more than 90% of the binder.

[0013] In other characteristics, the second temperature of the mixture in the second extruder is less than 150 °C. The process includes dispensing the active material layer onto a carrier film. The process includes dispensing the active material layer as a self-supporting film. The process includes pressing and heating the active material layer and laminating the active material layer onto a current collector.

[0014] A method for manufacturing a cathode electrode of a battery cell, not independently claimed, comprises supplying a dry powder mixture comprising a cathode active material, a conductive additive, and a binder to a first inlet of an extruder; mixing the cathode active material, the conductive additive, and the binder in a first section of the extruder; partially fibrillating the binder in the first section of the extruder; supplying a first solvent to a second section of the extruder; further, partially fibrillating the binder in the second section of the extruder; supplying a second solvent to a third section of the extruder; fibrillating the binder in the third section of the extruder; and forming an active material layer using a slotted die arranged at an outlet of the third section of the extruder.

[0015] In other respects, the binder is selected from a group consisting of polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), perfluoroalkoxyalkane (PFA), ethylenetetrafluoroethylene (ETFE), polyethylene (PE) and / or mixtures thereof. The particle size of the binder ranges from 1 µm to 1000 µm.

[0016] In other characteristics, the first solvent is selected from a group consisting of alcohols, esters, and combinations thereof. The first solvent constitutes 5 to 10 wt% of a mixture in the second section of the extruder. The second solvent is selected from a group consisting of alcohols, esters, and combinations thereof. The second solvent constitutes 5 to 10 wt% of a mixture in the third section of the extruder.

[0017] In other features, the process includes that the partial fibrillation of the binder in the first section of the extruder comprises fibrillation of the binder in a range of 20% to 40%, the partial fibrillation of the binder in the second section of the extruder comprises fibrillation of the binder in a range of 60% to 80%, and the fibrillation of the binder in the third section of the extruder comprises fibrillation of the binder to more than 90%.

[0018] Other characteristics include an extruder temperature greater than 70 °C and less than 150 °C. The process includes applying the active material layer to a carrier film. The process includes applying the active material layer as a self-supporting film. The process includes pressing and heating the active material layer. The process includes laminating the active material layer onto a current collector.

[0019] Further applications of the present disclosure will become apparent from the detailed description, the claims, and the drawings. The detailed description and the specific examples serve only for illustration. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present disclosure will be better understood with the help of the detailed description and the accompanying drawings, whereby: Fig. 1 a side cross-section of an example of a battery cell with C cathode electrodes, A anode electrodes and S separators according to the present disclosure; Fig. 2A and Fig. 2B lateral cross-sections of examples of a cathode electrode or an anode electrode according to the present disclosure are; Fig. 3 a functional block diagram of an example of a stepwise extrusion process for producing a self-supporting active material layer according to the present disclosure; Fig. 4 Functional block diagram of another example of a stepwise extrusion process for producing a self-supporting active material layer according to the present disclosure is; Fig. 5 is a functional block diagram of an example for rolling and heating the active material layer according to the present disclosure; and Fig. 6 is a functional block diagram illustrating an example of laminating the active material layer onto a current collector according to the present disclosure.

[0021] Reference symbols can be reused in the drawings to identify similar and / or identical elements. DETAILED DESCRIPTION

[0022] Although battery cells are shown in connection with electric vehicles according to the present disclosure, the battery cells can be used in stationary applications and / or other applications.

[0023] The present disclosure relates to a roll-to-roll (R2R) process for producing an active material layer for anode and / or cathode electrodes of a battery cell using a semi-dry powder. In some examples, a stepwise extrusion process is used to produce a thick electrode, in which a dry powder containing cathode or anode active material, a conductive additive (such as carbon), a binder (such as polytetrafluoroethylene (PTFE)), and a manufacturable solvent (such as alcohol) is used as a processing solvent.

[0024] In some examples, the dry powder is actively premixed in a first extruder to ensure uniform blending of the components and partial fibrillation of the binder. The mixture from the first extruder is fed to the inlet of a second extruder. A processing solvent is also added to the second extruder, and the binder is further fibrillated. In some examples, the second extruder outputs a self-supporting active material layer, the film thickness of which is controlled by a nozzle located at the outlet of the second extruder. In some examples, the second extruder outputs an active material layer onto a carrier film (e.g., a polyester (PET) film).

[0025] With the following reference to Fig. 1 comprises a battery cell 10, cathode electrodes 20, anode electrodes 40, and separators 32, arranged in a predetermined order in a battery cell stack 12, where C, S, and A are integers greater than zero. The battery cell stack 12 is arranged in a housing 50. The housing 50 contains a liquid electrolyte 52.

[0026] The C cathode electrodes 20-1, 20-2, ... and 20-C comprise a cathode active material layer 24 arranged on one or both sides of a cathode current collector 26. The A anode electrodes 40-1, 40-2, ... and 40-A comprise anode active material layers 42 arranged on one or both sides of the anode current collectors 46. The S separators 32-1, 32-2 ... and 32-S are arranged between the C cathode electrodes 20 and the A anode electrodes 40.

[0027] In some examples, the A anode electrodes 40 and the C cathode electrodes 20 exchange lithium ions during charging / discharging. In some examples, the cathode active material layers 24 and / or the anode active material layers 42 comprise coatings with one or more active materials, one or more conductive additives, and / or one or more binder materials, which are cast or applied to one or both sides of the current collectors 26 and / or 46.

[0028] In some examples, the cathode current collector 26 and / or the anode current collector 46 comprise metal foil, metal mesh, perforated metal, three-dimensional (3D) metal foam, and / or expanded metal. In some examples, the current collectors are made of one or more materials selected from the group consisting of copper, stainless steel, brass, bronze, zinc, aluminum, and / or their alloys. External tabs 28 and 48 are connected to the current collectors of the cathode and anode electrodes and may be located on the same or different sides of the battery cell stack 12. The external tabs 28 and 48 are connected to the terminals of the battery cells.

[0029] With the following reference to Fig. 2A and Fig. Figure 2B shows examples of the electrodes. Fig. 2A shows one of the C cathode electrodes 20 in more detail. The cathode active material layer 24 comprises a cathode active material 62, a conductive additive 64, and a binder 66. Fig. Figure 2B shows one of the anode electrodes 40 in more detail. The anode active material layer 42 comprises an anode active material 72, a conductive additive 74, and a binder 76.

[0030] With the following reference to Fig. Figure 3 shows a stepwise extrusion process with two or more extruders connected in series. A first extruder 110 comprises a screw 112 rotatably mounted in a housing 115. A die 114 may be arranged at the outlet of the first extruder 110. A mixture discharged from the first extruder 110 is fed to a second extruder 120, which comprises a screw 122 mounted in a housing 125. A die 124 (such as a slot die) is arranged at the outlet of the second extruder 120.

[0031] A dry powder 130, comprising a mixture of cathode or anode active material, a conductive filler, and a binder, is fed to an inlet 134 of the first extruder 110. The screw 112 of the first extruder 110 rotates within the housing 115 to mix and / or shear the dry powder. The first extruder 110 fibrillates the binder, at least partially.

[0032] The mixture discharged from the first extruder 110 is fed to a first inlet 144 of the second extruder 120. A liquid feed 148 supplies solvent to a second inlet 150 of the second extruder 120. In some examples, the solvent is selected from a group consisting of alcohols, esters, and combinations thereof. The screw 122 of the second extruder 120 rotates within the housing 125 to mix and further shear the dry powder. The second extruder 120 fibrillates the binder. The die 124 of the second extruder 120 discharges an active material layer 160 as a self-supporting film, or the active material layer 160 is discharged onto a carrier film 172 fed from a roll 170.

[0033] In some examples, the first extruder 110 fibrillates the binder to a degree of 10% to 40%. In some examples, the temperature of the mixture in the first extruder 110 is within a specified temperature range of 19°C to 70°C. In some examples, the solvent content is between 5% and 20% by weight of the mixture. In some examples, the temperature of the mixture in the second extruder 120 is maintained within a specified temperature range of 70°C to 150°C. In some examples, the binder is fibrillated to a degree greater than 90% (e.g., 100%) in the second extruder 120. Heaters (not shown) can be used to control the temperature of the first extruder 110 and / or the second extruder 120.

[0034] With the following reference to Fig. Figure 4 shows another stepwise extrusion process using a single extruder. An extruder 210 comprises a screw 212 rotatably mounted in a housing 213. The screw 212 of the extruder 210 rotates within the housing 213 to mix and shear the dry powder and to fibrillate the binder stepwise. A die 214, for example a slot die, is arranged at an outlet of the extruder 210.

[0035] A dry powder 220, comprising an anode or cathode active material, a conductive filler, and a binder, is fed to an inlet 224 of a first section of the extruder 210. In the first section, the dry powder is mixed and the binder is partially fibrillated. A first liquid feed 230 supplies solvent to a second inlet 234 in a second section of the extruder 210. In the second section of the extruder 210, the mixture is mixed / sheared and the binder is further fibrillated. A second liquid feed 240 supplies solvent to a second inlet 234 in a third section of the extruder 210. In the third section of the extruder 210, the mixture is mixed / sheared and the binder is further fibrillated. The nozzle 214 of the extruder 210 outputs an active material layer 250 as a self-supporting film, or the active material layer 250 is output onto a carrier film 262 supplied from a roll 260.

[0036] In some examples, the first solvent is selected from a group consisting of alcohols, esters, and combinations thereof. The first solvent constitutes 5 to 10 wt% of the mixture in the second section of extruder 210. The second solvent is selected from a group consisting of alcohols, esters, and combinations thereof. In some examples, the first and second solvents are identical. The second solvent constitutes 5 to 10 wt% of the mixture in the third section of extruder 210.

[0037] The binder is fibrillated in stages. In other words, the binder is fibrillated successively in the sections of extruder 210. In some examples, the binder is partially fibrillated in the first section of extruder 210 to a degree of 20% to 40%. In the second section of extruder 210, the binder is partially fibrillated to a degree of 60% to 80%. In the third section of extruder 210, the binder is fibrillated to more than 90% (e.g., 100%). In some examples, the mixture temperature in extruder 210 is more than 70°C and less than 150°C. A heater (not shown) can be used to control the temperature of extruder 210.

[0038] With the following reference to Fig. 5. In some examples, the active material layers 160 / 250 pass through a first set of rollers 310 and 312 and a second set of rollers 320 and 322 to reduce the film thickness. After rolling and pressing, the active material layer is heated in an oven 330 to a temperature in the range of 19 °C to 150 °C and collected on a roll 334. In some examples, the active material layers 160 / 250 are heated to a temperature in the range of 80 °C to 100 °C.

[0039] With the following reference to Fig. 6. A roller 350 feeds an active material layer 352 between rollers 366 and 368. Roller 360 feeds a current collector 364 between rollers 366 and 368. Rollers 366 and 368 press and / or heat the active material layer 352 and the current collector 364 to form an electrode 372 (which is collected on roller 374). In some examples, a heat-sensitive adhesive can be applied to one or both opposing surfaces to fix the active material layer 352 and the current collector 364 in place.

[0040] In some examples, the binder is selected from a group consisting of polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), perfluoroalkoxyalkane (PFA), ethylenetetrafluoroethylene (ETFE), polyethylene (PE), or combinations thereof. In some examples, the particle size of the binder ranges from 1 µm to 1000 µm. In some examples, the particle size of the binder ranges from 100 µm to 170 µm (e.g., 110 µm or 150 µm). In some examples, the particle size of the binder ranges from 1 µm to 50 µm.

[0041] In some examples, the solids content of the mixture ranges from 75 to 95 wt.%. In some examples, the solids content of the mixture ranges from 80 to 90 wt.%.

[0042] In some examples, the solvent is selected from a group consisting of alcohols, esters, and combinations thereof. In some examples, the solvent is easy to manufacture. In some examples, the solvent constitutes 5 to 40% by mass. In some examples, the solvent is fed into extruder 210 twice, either in equal or unequal proportions. Fig. 4 given.

[0043] It is understood that one or more steps within a process may be carried out in a different order (or simultaneously) without deviating from the fundamental concept of this disclosure. Even though each of the embodiments described above has certain features, one or more of these features, described in relation to any embodiment of the disclosure, may be implemented in any other embodiment and / or combined with features of any other embodiment, even if such combination is not expressly described. In other words, the described embodiments are not mutually exclusive, and combinations of one or more embodiments remain within the scope of this disclosure.

[0044] Spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including "connected," "interlocking," "coupled," "adjacent," "next to," "on," "above," "below," and "arranged." Unless a relationship between a first and a second element is explicitly described as "direct" in the above disclosure, this relationship may be a direct relationship, in which no other intervening elements exist between the first and the second element, or it may be an indirect relationship, in which one or more intervening elements (either spatial or functional) exist between the first and the second element.As used herein, the phrase “A, B and / or C” should be interpreted using a non-exclusive logical OR operation as logical (A OR-connected with B OR-connected with C) and not as “at least one of A, at least one of B and at least one of C”.

Claims

[1] Method for manufacturing a cathode electrode (20) for a battery cell (10), comprising: Providing a dry powder mixture (130) comprising an active material (62), a conductive additive (64) and a binder (66) to a first extruder; Mixing the active material (62), the conductive additive (64) and the binder (66) in the first extruder (110); Partial fibrillation of the binder (66) in the first extruder (110); Feeding a mixture from the first extruder (110) to a first inlet (144) of a second extruder (120); Supplying a solvent to a second inlet (150) of the second extruder (120); Mixing the active material (62), the conductive additive (64), the binder (66) and the solvent in the second extruder (120); Fibrillation of the binder (66) in the second extruder (120); and Forming an active material layer (24, 160, 250, 352) using an extrusion nozzle (124) located at an outlet of the second extruder (120). [2] Method according to claim 1, wherein: a first temperature of the first extruder (110) is in a range of 19 °C to 70 °C, and a second temperature of the second extruder (120) is greater than 70 °C. [3] Method according to claim 1, wherein: the binder (66) is selected from a group consisting of polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), perfluoroalkoxyalkane (PFA), ethylenetetrafluoroethylene (ETFE), polyethylene (PE) and combinations thereof, and a particle size of the binder (66) is in a range of 1 µm to 1000 µm. [4] Method according to claim 3, wherein the particle size of the binder (66) is in a range of 1 µm to 50 µm. [5] Method according to claim 1, wherein: the solvent is selected from a group consisting of alcohols, esters and combinations thereof, and The solvent makes up 5 to 20 wt.% of the mixture. [6] Method according to claim 1, wherein: the partial fibrillation of the binder (66) in the first extruder (110) includes fibrillation of the binder (66) in a range of 10% to 40%, and the fibrillation of the binder (66) in the second extruder (120) includes fibrillation of the binder (66) to more than 90%. [7] Method according to claim 2, wherein the second temperature of the mixture in the second extruder (120) is less than 150 °C. [8] Method according to claim 1, further comprising applying the active material layer (24, 160, 250, 352) onto a carrier film (172, 262). [9] Method according to claim 1, further comprising outputting the active material layer (24, 160, 250, 352) as a self-supporting film. [10] Method according to claim 1, further comprising: Pressing and heating the active material layer (24, 160, 250, 352); and Laminating the active material layer (24, 160, 250, 352) onto a current collector (26, 364).

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