Electrode foil wrinkle removal tape

Abstract

Aspects of the disclosure include an electrode calendering system with an electrode foil wrinkle removal belt and a method for manufacturing electrodes using the same. An exemplary system comprises an upper roller press and a lower roller press separated from the upper roller press by a gap. The gap includes a distance selected to accommodate a current collector with a bare portion and a coated portion, the latter bearing an electrode active material of a first thickness. The system further comprises a wrinkle removal belt of a second thickness, selected based on the first thickness, to distribute voltage evenly over the bare and coated portions of the current collector during a calendering process to form a pressed electrode.

Description

INTRODUCTION

[0001] The present disclosure relates to the manufacture of battery cells and, more particularly, to an electrode calendering system having an electrode foil dewrinkle belt.

[0002] Electrodes are used in a variety of devices that store electrical energy, including primary (non-rechargeable) battery cells, secondary (rechargeable) battery cells, fuel cells, and capacitors. An ideal electrode must combine several electrical energy storage properties, such as energy density, power density, maximum charge rate, internal leakage current, equivalent series resistance (ESR), cycle endurance, high electrical conductivity, and low torsion. Electrodes often incorporate current collectors to complement or otherwise enhance these electrical energy storage properties. Current collectors can be added to achieve higher conductivity and increase the available contact area to minimize the interfacial contact resistance between the electrode and its terminal.

[0003] A current collector is typically a plate of conductive material to which the electrode active material is attached. Commonly used current collectors for an electrode include aluminum foil, aluminum alloy, copper alloy, stainless steel, and titanium foil. In some electrode manufacturing processes, for example, a film containing activated carbon powder (i.e., the electrode active material) is attached to a thin aluminum or copper foil with an adhesive layer. To improve the quality of the interfacial bond between the film of electrode active material and the current collector, the combined film and current collector are processed in a pressure laminator, such as a calender. This process is commonly referred to as calendering. Therefore, the manufacture of an electrode typically involves preparing a film of electrode active material and laminating this film to a current collector. SUMMARY

[0004] In an exemplary embodiment, an electrode calendering system with an electrode foil dewrinkle belt for manufacturing electrodes is provided. The system includes an upper roll press and a lower roll press separated from the upper roll press by a nip. The nip includes a distance selected to accommodate a current collector having a bare portion and a coated portion having an electrode active material having a first thickness thereon. The system further includes a dewrinkle belt having a second thickness selected based on the first thickness to evenly distribute stress across the bare portion and the coated portion of the current collector during a calendering process to form a pressed electrode.

[0005] In addition to one or more of the features described herein, in some embodiments the system includes a tape guide roller and / or a tension roller configured to align the de-wrinkle tape with the bare portion of the current collector.

[0006] In some embodiments, the system includes a servo system coupled to the tape guide roller and / or the tension roller. The servo system may include a servo motor and one or more rollers configured to reposition the de-wrinkle tape to maintain alignment with the bare portion of the current collector.

[0007] In some embodiments, the wrinkle removal tape is an upper wrinkle removal tape disposed over an upper surface of the bare portion of the current collector. In some embodiments, the wrinkle removal tape is a lower wrinkle removal tape disposed over a lower surface of the bare portion of the current collector.

[0008] In some embodiments, the wrinkle removal tape is one of an upper wrinkle removal tape disposed over an upper surface of the bare portion of the current collector and a lower wrinkle removal tape disposed over a lower surface of the bare portion of the current collector, and the system further includes a second wrinkle removal tape that is the other of the upper wrinkle removal tape and the lower wrinkle removal tape.

[0009] In some embodiments, the second thickness of the wrinkle removal band is tapered.

[0010] In some embodiments, the wrinkle removal band is disposed over a top surface of the bare portion of the current collector, and the second thickness of the wrinkle removal band includes a positive taper that increases toward an edge of the current collector.

[0011] In some embodiments, the wrinkle removal band is disposed over a lower surface of the bare portion of the current collector, and the second thickness of the wrinkle removal band includes a positive taper that increases toward an edge of the current collector.

[0012] In another exemplary embodiment, a method for manufacturing electrodes is provided. The method includes providing an upper roll press and a lower roll press separated from the upper roll press by a gap. The gap includes a distance selected to accommodate a current collector. The current collector includes a bare portion and a coated portion having an electrode active material having a first thickness thereon. The method includes providing a wrinkle removal tape having a second thickness selected based on the first thickness to evenly distribute stress across the bare portion and the coated portion of the current collector during a calendering process to form a pressed electrode.

[0013] In some embodiments, the method includes providing a tape guide roller and / or a tension roller configured to align the de-wrinkle tape with the bare portion of the current collector.

[0014] In some embodiments, the method includes providing a servo system coupled to the tape guide roller and / or the tension roller. The servo system includes a servo motor and one or more rollers configured to reposition the de-wrinkle tape to maintain alignment with the bare portion of the current collector.

[0015] In some embodiments, the wrinkle removal band comprises an upper wrinkle removal band disposed over an upper surface of the bare portion of the current collector.

[0016] In some embodiments, the wrinkle removal band comprises a lower wrinkle removal band disposed over a lower surface of the bare portion of the current collector.

[0017] In some embodiments, the wrinkle removal tape comprises one of an upper wrinkle removal tape disposed over an upper surface of the bare portion of the current collector and a lower wrinkle removal tape disposed over a lower surface of the bare portion of the current collector. In some embodiments, the method further comprises providing a second wrinkle removal tape that is the other of the upper wrinkle removal tape and the lower wrinkle removal tape.

[0018] In some embodiments, the second thickness of the wrinkle removal band is tapered.

[0019] In some embodiments, the wrinkle removal band is disposed over a top surface of the bare portion of the current collector, and the second thickness of the wrinkle removal band includes a positive taper that increases toward an edge of the current collector.

[0020] In some embodiments, the wrinkle removal band is disposed over a lower surface of the bare portion of the current collector, and the second thickness of the wrinkle removal band includes a positive taper that increases toward an edge of the current collector.

[0021] In some embodiments, the wrinkle removal tape is configured as a plurality of separate tapes disposed over the bare portion of the current collector for web coating applications.

[0022] The above features and advantages, as well as other features and advantages of the disclosure, will be readily apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Further features, advantages and details are included only as examples in the following detailed description, which refers to the drawings. Fig. 1 is a vehicle configured according to one or more embodiments; Fig. 2 is an exemplary configuration of an electrode calendering system according to one or more embodiments; Fig. 3A is a view of an electrode calendering system according to one or more embodiments; Fig. 3B is a view of an alternative electrode calendering system according to one or more embodiments; Fig. 4A is a view of an alternative electrode calendering system according to one or more embodiments; Fig. 4B is a view of an alternative electrode calendering system according to one or more embodiments; Fig. 4C is a view of an alternative electrode calendering system according to one or more embodiments; Fig. 5A is a view of an alternative electrode calendering system according to one or more embodiments; Fig. 5B is a view of an alternative electrode calendering system according to one or more embodiments; Fig. 5C is a view of an alternative electrode calendering system according to one or more embodiments; and Fig. 6 is a flowchart according to one or more embodiments. DETAILED DESCRIPTION

[0024] The following description is merely exemplary and is not intended to limit the present disclosure, its application, or uses. It should be understood that throughout the drawings, corresponding reference characters designate like or corresponding parts and features.

[0025] Electrodes often contain current collectors to complement or otherwise enhance the electrical energy storage properties of the final integrated device (e.g., a battery). A current collector typically comprises a foil of conductive material (e.g., aluminum foil, copper foil, etc.) to which an electrode active material is attached. To improve the quality of the interfacial bond between the foil of electrode active material and the current collector, the combined foil and current collector are processed in a pressure laminator. Therefore, the fabrication of an electrode typically involves fabricating a foil of electrode active material and laminating this foil to a current collector (the so-called calendering process).

[0026] Calendering can be broadly defined as the compression of a dried electrode (usually resulting from coating and drying an electrode slurry) to reduce its porosity, improve particle contact, and increase energy or power density. Conventional calendering processes have been used to improve various aspects of battery technology, for example, by providing higher specific conductivity, larger contact areas, and lower contact resistance in the electrode. However, several challenges exist in optimizing the calendering process.

[0027] One such challenge, for example, is that calendering electrodes (e.g., cathodes) onto current collector supports (e.g., foil supports such as aluminum, stainless steel, and titanium) results in a wrinkling defect when lower porosity is desired. Wrinkling (also known as uneven stretching) occurs at the interface between the coated sections of the current collector (i.e., the parts with pressed electrode foils) and the uncoated sections (i.e., the bare sections of the current collector) and is caused by the different material properties and thicknesses of the electrode and support materials. These defects worsen as the resulting porosity decreases, meaning that electrodes with relatively low porosity are inherently more affected by wrinkling.

[0028] While there are several approaches to reducing wrinkling, each carries some trade-off. For example, the naive approach is to increase the target porosity, which leads to a proportional reduction in wrinkling but at the expense of lower electrode conductivity. Another approach is to completely cover the support, so there is no interface where wrinkling defects can occur. The trade-off is that the bare foil sections of the current collector (i.e., the parts not covered by the electrode active material) are ideal for use as battery terminals, and simply removing the bare foil sections reduces battery efficiency.

[0029] This disclosure presents a novel electrode calendering system having an electrode foil de-wrinkle belt and a method for manufacturing electrodes using the same. Instead of increasing porosity targets or removing (or reducing) the bare foil portions of an electrode, an electrode calendering system described herein utilizes the electrode foil de-wrinkle belt to evenly distribute stress during the calendering process. In some embodiments, the de-wrinkle belt is placed over the bare foil portion of the current collector at the interface with the coated portion to transfer compressive forces from the calendering rolls to the bare foil, maintaining the same compression as the coated portions.Maintaining uniform compression during the calendering process reduces (or eliminates) wrinkling and results in uniform stretching across all sections of the pressed electrode. In some embodiments, the dewrinkle belt is positioned over the current collector using a system of tension rollers to improve alignment. In some embodiments, the dewrinkle belt is actively guided (positioned and repositioned) on the current collector using a servo system that tracks the position of the dewrinkle belt and / or the current collector to improve alignment.

[0030] The use of an electrode calendering system with a wrinkle removal belt configured according to one or more embodiments offers several technical advantages over previous designs. The modified manufacturing system and associated process described in this document can be used to produce electrodes without wrinkle defects (or with greatly reduced wrinkle defects) and with relatively improved elongation. Batteries made from electrodes without wrinkles and with more uniform elongation offer several improved battery properties, as these defects can compromise the integrity of the electrodes (e.g., wrinkles can lead to poor adhesion between the coated electrode foil and the current collector, resulting in areas of relatively weak attachment that are prone to delamination or delamination).increase electrical resistance (wrinkles and thickness variations can create gaps or areas of reduced contact between the electrode material and the current collector, which can impede electron flow), increase degradation and reduce cycle life (electrodes with wrinkles and / or uneven stretching can be subjected to increased stress and strain during charge-discharge cycling due to uneven mechanical properties, which can lead to accelerated degradation, cracking, or even electrode failure), increase thermal instability (wrinkles can trap electrolyte and impede heat dissipation, resulting in local hotspots that can degrade the electrolyte), and reduce capacity and energy density (wrinkle formation and stretching defects can lead to uneven thickness distribution across the electrode surface),and these non-uniformities can lead to lower utilization of the active material, lower capacity, and lower energy density in the battery). Further advantages are possible. For example, while a roller press can be redesigned to allow for the application and removal of support material, aspects of the present disclosure can be used to modify existing roller presses for reducing wrinkle defects by adding a wrinkle removal belt and some positioning and tensioning rolls without having to redesign the main roll / calendering roll. Finally, reducing wrinkle and stretch defects through the use of a wrinkle removal belt, as described herein, eliminates the need for foil annealing and foil consolidation, as well as the need to introduce ribs into the current collector, all of which are techniquesThese are typically used to reduce defects, but are known to weaken the film. Furthermore, the annealing and film consolidation steps are energy-intensive and expensive.

[0031] A vehicle according to an exemplary embodiment is shown in Fig. 1. Generally designated 100. The vehicle 100 is illustrated in the form of an automobile having a body 102. The body 102 includes a passenger compartment 104 in which a steering wheel, front seats, and rear seats (not separately indicated) are disposed. Disposed within the body 102 are a number of components, including, for example, an electric motor 106 (shown by projection under the front hood). The electric motor 106 is shown only for ease of illustration and discussion. It should be understood that the configuration, location, size, arrangement, etc., of the electric motor 106 is not intended to be particularly limited, and that all such configurations (including multiple motor configurations) are within the intended scope of this disclosure.

[0032] The electric motor 106 is powered by a battery pack 108 (shown by projection near the rear of the vehicle 100). The battery pack 108 is shown only for ease of illustration and discussion. It should be understood that the configuration, location, size, arrangement, etc., of the battery pack 108 is not intended to be particularly limited, and that all such configurations (including split configurations) fall within the intended scope of this disclosure. Although the present disclosure is primarily discussed in the context of a battery pack 108 configured for the electric motor 106 of the vehicle 100, the aspects described herein may similarly be incorporated into any system (vehicle, building, or other) having one or more energy storage systems (e.g.,one or more battery packs), and all such configurations and applications fall within the intended scope of this disclosure.

[0033] As explained in more detail below, the battery pack 108 includes one or more cells with electrodes having improved edge quality (i.e., uniform stretching and reduced or eliminated wrinkles). In some embodiments, an electrode calendering system is modified to include a wrinkle removal belt (see Fig. 2 and Fig. 3A). In some embodiments, the wrinkle removal belt is actively positioned using a servo system (see Fig. 3B). In some embodiments, the wrinkle removal tape is placed over both surfaces (top and bottom) of the current collector (see Fig. 4A). In some embodiments, the wrinkle removal tape is placed over one of the surfaces (top or bottom) of the current collector (see Fig. 4B and Fig. 4C). In some embodiments, the wrinkle removal tape is configured as a plurality of tapes that are placed over the bare foil portions of a current collector for web coating applications (see Fig. 5A). In some embodiments, the single-coat wrinkle removal tape is applied over one of the surfaces (top or bottom) of the current collector (see Fig. 5B and Fig. 5C).

[0034] Fig. 2 shows an exemplary configuration of an electrode calendering system 200 according to one or more embodiments. As shown in Fig. 2, the electrode calendering system 200 may include a coated current collector 202 that is passed between an upper roll press 204 and a lower roll press 206 for calendering. In some embodiments, the coated current collector 202 (also referred to as a coated web) is passed through the upper roll press 204 and the lower roll press 206 by means of a series of guide rolls 208. In some embodiments, the coated current collector 202 is wound into a coated electrode roll following a coating process (not separately shown). In some embodiments, the coated current collector 202 is unwound from the coated electrode roll and coupled to the guide rolls 208 for calendering. After calendering (e.g.,After passing through the upper roller press 204 and the lower roller press 206, the coated current collector 202 may be referred to as a pressed electrode 210.

[0035] In some embodiments, the coated current collector 202 comprises a current collector coated with an electrode active material. Without intending any particular limitation, the electrode active material may, for example, comprise various cathode or anode materials (depending on the requirements of a particular application), such as activated carbon powder, nickel manganese cobalt oxide (NMC), lithium iron phosphate (LFP), nickel cobalt aluminum oxide (NCA), nickel cobalt manganese aluminum oxide (NCMA), lithium manganese iron phosphate (LMFP), lithium manganese rich (LMR), lithium manganese oxide (LMO), graphite, silicon, silicon graphite composites, tin, tin oxide (SnO2), lithium titanate (Li4Ti5O 12, LTO), sulfur and lithium-sulfur (Li-S) composites, lithium metal (Li) and / or lithium alloys such as lithium antimony (Li-Sb), lithium aluminum (Li-Al) and lithium germanium (Li-Ge) and the like.

[0036] The current collector (also referred to as a sheet or bare foil) is also not particularly limited, but can, for example, comprise a sheet of conductive metal such as aluminum foil, stainless steel, and titanium foil. Other materials are possible, such as semi-metals (e.g., tin, graphite), alloys of the metals and / or semi-metals, conductive two-dimensional wire mesh, conductive three-dimensional wire mesh, conductive foam, and the like.

[0037] In some embodiments, the upper roller press 204 and the lower roller press 206 are arranged to apply pressure to the coated current collector 202. This process, referred to as calendering, is intended to improve the density, uniformity, and overall performance of the resulting pressed electrode 210 by compressing and densifying an electrode material onto a portion of a current collector. The upper roller press 204 and the lower roller press 206 can be made of a durable material such as steel and manufactured with precision surfaces (e.g., with tolerances below 10 microns) to ensure even pressure distribution. In some embodiments, the upper roller press 204 is arranged vertically above the lower roller press 206, and a gap (not separately shown) can be created by (e.g.,hydraulic) movement of the upper roller press 204 or the lower roller press 206 or both to control the strength of the applied pressure.

[0038] In some embodiments, the electrode calendering system 200 includes several control parameters, such as a roll temperature (top and / or bottom), a calendering pressure, a nip distance, and a machine speed. In some embodiments, the roll temperature is up to 150 degrees Celsius, the pressure is up to 10 MPa, and the machine speed is 110 meters per minute, although other calendering configurations are contemplated within the scope of this disclosure. In some embodiments, the nip between the upper roll press 204 and the lower roll press 206 can be adjusted (hydraulically or otherwise) to the desired thickness of the pressed electrode 210.

[0039] When the upper roller press 204 and / or the lower roller press 206 applies pressure, the coated current collector 202 is compressed. This improves the density of the pressed electrode 210, removes voids and air pockets, and improves the contact between the electrode active material and the current collector. The calendering process also results in a reduction in the thickness of the coated current collector 202 because the pressed electrode 210 is flattened under the pressure of the rollers.

[0040] In some embodiments, the electrode calendering system 200 includes an upper dewrinkle belt 212 and / or a lower dewrinkle belt 214. In some embodiments, the presence of the upper dewrinkle belt 212 and / or the lower dewrinkle belt 214 ensures that the tension applied to the bare film portions of the coated current collector 202 is the same as the tension applied to the coated portions of the coated current collector 202.

[0041] In some embodiments, the thickness of the upper dewrinkle band 212 and / or the lower dewrinkle band 214 is selected for a particular application to ensure even stress distribution. It should be noted that the thickness required for even stress distribution depends on the loading (e.g., milligrams per square centimeter) and the density of the electrode material, the material chosen for the current collector, and the desired thickness of the pressed electrode 210. Furthermore, the band thickness can be selected based on a number of design and / or target parameters, such as flexural strength, deformation, elongation, electrode thickness, and / or yield strength. The band thickness can also vary based on additional factors, including electrode formulation, surface roughness, tensile properties, and the like.

[0042] The upper dewrinkle belt 212 and / or the lower dewrinkle belt 214 may be made of a material with known elasticity under the intended calendering pressures. Without particular limitation, the upper dewrinkle belt 212 and / or the lower dewrinkle belt 214 may be made, for example, of silicon blended with a polymer such as polypropylene, thermoplastic polymers such as polyethylene terephthalate (PET) and polyvinylidene fluoride (PVDF), polyethylene (PE) including low-density polyethylene (LDPE) and high-density polyethylene (HDPE), polytetrafluoroethylene (PTFE), polyamides such as nylon, synthetic rubber such as neoprene, hybrid materials with glass fibers, silicon oxide, etc., polymers and metal laminates with rubber, and the like.In some embodiments, the upper dewrinkle belt 212 and / or the lower dewrinkle belt 214 may be made of a highly elastic material to minimize tool wear and enable continuous calendering operation over multiple cycles. The term "highly elastic" material, as used herein, refers to a material having a Young's modulus of less than 3 gigapascals (GPa). In some embodiments, the highly elastic material has a Young's modulus of less than 1 GPa, such as rubber (about 0.01 to 0.1 GPa). In some embodiments, the highly elastic material has a Young's modulus of less than 0.1 GPa, such as an elastomer (about 0.001 to 0.1 GPa).

[0043] In some embodiments, the upper de-wrinkle belt 212 and / or the lower de-wrinkle belt 214 are guided through the upper roll press 204 and the lower roll press 206 using a series of belt guide rollers 216, in a manner similar to that previously described with respect to the coated current collector 202 and the guide rollers 208. In some embodiments, the upper de-wrinkle belt 212 and the lower de-wrinkle belt 214 are guided through the upper roll press 204 and the lower roll press 206 using separate belt guide rollers 216 (as shown), although other configurations having common belt guide rollers 216 are contemplated within the scope of this disclosure.

[0044] In some embodiments, the electrode coating system 200 includes one or more tension rollers 218 coupled to the upper de-wrinkle belt 212 and / or the lower de-wrinkle belt 214 and configured to maintain a uniform and controlled tension while the upper de-wrinkle belt 212 and / or the lower de-wrinkle belt 214 undergo the calendering process. In some embodiments, each group of separate belt guide rollers 216 includes one or more tension rollers 218 (as shown).

[0045] In some embodiments, the electrode coating system 200 includes a support structure 220 for the upper roll press 204, the lower roll press 206, the guide rollers 208, the strip guide rollers 216, and / or the tension rollers 218. The support structure 220 may, for example, comprise a steel frame, but other materials are also contemplated within the scope of this disclosure.

[0046] Fig. 3A shows a view of an electrode calendering system 300 according to one or more embodiments. In some embodiments, the electrode calendering system 300 is part of a calendering system (e.g., the electrode calendering system 200 of Fig. 2). As in Fig. 3A, the electrode calendering system 300 may include the upper roller press 204, the lower roller press 206, the upper dewrinkle belt 212, and the lower dewrinkle belt 214 configured and arranged as shown.

[0047] In some embodiments, a current collector 302 is coated with an electrode active material 304 and passed between the upper roller press 204 and the lower roller press 206 for calendering. In some embodiments, both surfaces (e.g., top and bottom) of the current collector 302 are coated with the electrode active material 304 (as shown). Alternatively, a single surface (e.g., top or bottom) of the current collector 302 may be coated with the electrode active material 304 (see Fig. 5B and Fig. 5C). The current collector 302 and the electrode active material 304 applied thereto together form a coated current collector, such as that described with reference to Fig. 2 described coated current collector 202.

[0048] In some embodiments, the upper dewrinkle belt 212 and the lower dewrinkle belt 214 can be configured to have a thickness that mimics the coating thickness of the electrode active material 304 pressed onto the current collector 302. For example, the upper roller press 204 and the lower roller press 206 can be separated by a gap G, and the upper dewrinkle belt 212 and the lower dewrinkle belt 214 can each have a thickness selected based on a thickness of the bare portions of the current collector 302 to ensure that the gap G is filled (as shown). In this way, the thickness difference between the coated and uncoated portions of the current collector 302 is greatly minimized (if not eliminated), thereby reducing wrinkling and achieving uniform elongation without compromising the porosity targets and / or the bare film surface.Consequently, the upper dewrinkle belt 212 and the lower dewrinkle belt 214 serve to more evenly distribute the calendering stresses during the calendering process, resulting in improved edge quality of the resulting pressed electrode (e.g., the pressed electrode 210).

[0049] Fig. 3B shows a view of an alternative electrode calendering system 350 according to one or more embodiments. In some embodiments, the electrode calendering system 350 is part of a calendering system (e.g., the electrode calendering system 200 of Fig. 2). As in Fig. 3B, the electrode calendering system 350 may include the upper roller press 204, the lower roller press 206, the upper dewrinkle belt 212, and the lower dewrinkle belt 214 configured and arranged as shown.

[0050] In some embodiments, a current collector 302 is coated with an electrode active material 304 and passed between the upper roller press 204 and the lower roller press 206 for calendering. In some embodiments, both surfaces (e.g., top and bottom) of the current collector 302 are coated with the electrode active material 304 (as shown). Alternatively, a single surface (e.g., top or bottom) of the current collector 302 may be coated with the electrode active material 304 (see Fig. 5B and Fig. 5C). The current collector 302 and the electrode active material 304 applied thereto together form a coated current collector, such as that described with reference to Fig. 2 described coated current collector 202.

[0051] In some embodiments, the upper wrinkle removal tape 212 and the lower wrinkle removal tape 214 may be configured to have a thickness that mimics the coating thickness of the electrode active material 304 pressed onto the current collector 302, as previously described with reference to Fig. 3A. For example, the upper roller press 204 and the lower roller press 206 may be separated by a gap G, and the upper dewrinkle belt 212 and the lower dewrinkle belt 214 may each have a thickness selected based on a thickness of the bare portions of the current collector 302 to ensure that the gap G is filled (as shown). In this way, the thickness difference between the coated and uncoated portions of the current collector 302 is greatly minimized (if not eliminated), thereby reducing wrinkling and achieving uniform elongation without compromising the porosity targets and / or the bare film surface.Consequently, the upper dewrinkle belt 212 and the lower dewrinkle belt 214 serve to more evenly distribute the calendering stresses during the calendering process, resulting in improved edge quality of the resulting pressed electrode (e.g., the pressed electrode 210).

[0052] In some embodiments, the electrode calendering system 350 includes one or more servo systems 352 for actively positioning the upper dewrinkle belt 212 and the lower dewrinkle belt 214 with respect to the current collector 302 and / or the electrode active material 304. In some embodiments, the servo systems 352 may be configured to ensure (or improve within the tool limits) the alignment between two or more of the upper dewrinkle belt 212, the lower dewrinkle belt 214, the current collector 302, and the electrode active material 304.

[0053] In some embodiments, each of the servo systems 352 includes a servo motor 354 and one or more rollers 356. The servo motor 354 is responsible for driving and / or repositioning the rollers 356 and / or other guide mechanisms (not separately shown) to accurately position the upper dewrinkle belt 212 and / or the lower dewrinkle belt 214. The servo motor 354 may, without particular limitation, comprise a motor with a high torque of approximately 10 Newton meters, speed control, and precise positioning capabilities. The servo systems 352 may include one or more sensors (not separately shown) coupled to the servo motor 354 and / or the rollers 356. The sensors may, for example, be position sensors (e.g.,optical encoders or linear position sensors) that continuously and / or periodically monitor the position of the upper dewrinkle belt 212, the lower dewrinkle belt 214, the current collector 302, and / or the electrode active material 304, and voltage sensors configured to measure the voltage in the upper dewrinkle belt 212, the lower dewrinkle belt 214, and / or the current collector 302. In some embodiments, the servo systems 352 may include control electronics (not separately shown), such as a microcontroller and / or a dedicated servo controller, to process feedback from the sensors and generate control signals for the servo motor.

[0054] Fig. 4A shows a view of an alternative electrode calendering system 400 according to one or more embodiments. In some embodiments, the electrode calendering system 400 is part of a calendering system (e.g., the electrode calendering system 200 of Fig. 2). As in Fig. 4A, the electrode calendering system 400 may include the upper roller press 204, the lower roller press 206, the upper dewrinkle belt 212, and the lower dewrinkle belt 214 configured and arranged as shown. Fig. 4A shows a dual belt configuration including both the upper wrinkle removal belt 212 and the lower wrinkle removal belt 214.

[0055] Fig. 4B shows a view of an alternative electrode calendering system 410 according to one or more embodiments. In some embodiments, the electrode calendering system 410 is part of a calendering system (e.g., the electrode calendering system 200 of Fig. 2). As in Fig. 4B, the electrode calendering system 410 may include the upper roller press 204, the lower roller press 206, and the upper dewrinkle belt 212 configured and arranged as shown. Fig. Figure 4B shows a single belt configuration with only the upper wrinkle removal belt 212.

[0056] As in Fig. 4B, the upper wrinkle removal band 212 may have a tapered profile (as shown, a positive taper that increases toward an edge of the current collector 302). In some embodiments, the shape, thickness, slope, and / or taper of the upper wrinkle removal band 212 are variable to evenly distribute the stress on the bare foil and the coated portions of the current collector 302. The specific taper used in Fig. 4B is for illustration and discussion purposes only.

[0057] The upper wrinkle removal belt 212 may have a tapered profile with a positive and / or negative slope. The degree of slope, which Fig. 4B is not intended to be particularly limited. Other taper profiles are possible, including linear and non-linear profiles, and all such configurations are contemplated within the scope of this disclosure. For example, the upper wrinkle removal band 212 may have a spherical, curved, pointed, square, triangular, and / or patterned taper profile, as desired.

[0058] Fig. 4C shows a view of an alternative electrode calendering system 420 according to one or more embodiments. In some embodiments, the electrode calendering system 420 is part of a calendering system (e.g., the electrode calendering system 200 of Fig. 2). As in Fig. 4C, the electrode calendering system 420 may include the upper roll press 204, the lower roll press 206, and the lower dewrinkle belt 214 configured and arranged as shown. Fig. Figure 4C shows a single belt configuration with only the lower wrinkle removal belt 214.

[0059] As in Fig. 4C, the lower wrinkle removal band 214 may have a tapered profile (as shown, a positive taper that increases toward an edge of the current collector 302). In some embodiments, the shape, thickness, slope, and / or taper of the lower wrinkle removal band 214 are variable to evenly distribute the stress on the bare foil and the coated portions of the current collector 302. The specific taper used in Fig. 4C is for illustration and discussion purposes only. The lower wrinkle removal band 214 may have a tapered profile with a positive and / or negative slope. The degree of slope shown in Fig. 4C is not intended to be particularly limited. Other taper profiles are possible, including linear and non-linear profiles, and all such configurations are contemplated within the scope of this disclosure. For example, the lower anti-wrinkle band 214 may have a spherical, curved, pointed, square, triangular, and / or patterned taper profile, as desired.

[0060] Fig. 5A shows a view of an alternative electrode calendering system 500 according to one or more embodiments. In some embodiments, the electrode calendering system 500 is part of a calendering system (e.g., the electrode calendering system 200 of Fig. 2). As in Fig. 5A, the electrode calendering system 500 may include the upper roller press 204, the lower roller press 206, the upper dewrinkle belt 212, and the lower dewrinkle belt 214 configured and arranged as shown. Fig. 5A shows a multiple band configuration in which the upper dewrinkle band 212 and the lower dewrinkle band 214 are each split into two or more bands across their respective surfaces of the current collector 302.

[0061] Fig. 5B shows a view of an alternative electrode calendering system 510 according to one or more embodiments. In some embodiments, the electrode calendering system 510 is part of a calendering system (e.g., the electrode calendering system 200 of Fig. 2). As in Fig. 5B, the electrode calendering system 510 may include the upper roll press 204, the lower roll press 206, and the upper dewrinkle belt 212 configured and arranged as shown. Fig. 5B shows a single-band configuration with only the upper dewrinkle band 212, since the electrode active material 304 is only applied to the upper surface 502 of the current collector 302 (e.g., a single coating operation).

[0062] Fig. 5C shows a view of an alternative electrode calendering system 520 according to one or more embodiments. In some embodiments, the electrode calendering system 520 is part of a calendering system (e.g., the electrode calendering system 200 of Fig. 2). As in Fig. 5C, the electrode calendering system 520 may include the upper roll press 204, the lower roll press 206, and the lower dewrinkle belt 214 configured and arranged as shown. Fig. 5C shows a single-band configuration with only the lower dewrinkle band 214, since the electrode active material 304 is only applied to the lower surface 504 of the current collector 302 (e.g., a single coating operation).

[0063] With reference now to Fig. 6 shows a flowchart 600 for the manufacture of electrodes using an electrode calendering system with an electrode foil de-wrinkle belt according to a general embodiment. The flowchart 600 is described with reference to Fig. 1-5C and can contain further Fig. 6 steps not shown. The Fig.Although the blocks shown in Figure 6 are presented in a specific order, they can be rearranged, subdivided and / or combined.

[0064] In block 602, the method includes providing an upper roller press.

[0065] In block 604, the method includes providing a lower roller press separated from the upper roller press by a gap. In some embodiments, the gap comprises a distance selected to accommodate a current collector. In some embodiments, the current collector includes a bare portion and a coated portion having an electrode active material having a first thickness thereon.

[0066] In block 606, the method includes providing a wrinkle removal tape having a second thickness selected based on the first thickness to evenly distribute stress across the bare portion and the coated portion of the current collector during a calendering process to form a pressed electrode.

[0067] In some embodiments, the method includes providing a tape guide roller and / or a tension roller configured to align the de-wrinkle tape with the bare portion of the current collector.

[0068] In some embodiments, the method includes providing a servo system coupled to the tape guide roller and / or the tension roller. The servo system may include a servo motor and one or more rollers configured to reposition the de-wrinkle tape to maintain alignment with the bare portion of the current collector.

[0069] In some embodiments, the wrinkle removal band is a top wrinkle removal band disposed over a top surface of the bare portion of the current collector.

[0070] In some embodiments, the wrinkle removal band is a lower wrinkle removal band disposed over a lower surface of the bare portion of the current collector.

[0071] In some embodiments, the wrinkle removal tape is one of an upper wrinkle removal tape disposed over an upper surface of the bare portion of the current collector and a lower wrinkle removal tape disposed over a lower surface of the bare portion of the current collector. In some embodiments, the method further comprises providing a second wrinkle removal tape that is the other of the upper wrinkle removal tape and the lower wrinkle removal tape.

[0072] In some embodiments, the second thickness of the wrinkle removal band is tapered.

[0073] In some embodiments, the wrinkle removal band is disposed over a top surface of the bare portion of the current collector, and the second thickness of the wrinkle removal band has a positive taper that increases toward an edge of the current collector.

[0074] In some embodiments, the wrinkle removal band is disposed over a lower surface of the bare portion of the current collector, and the second thickness of the wrinkle removal band is a positive taper that increases toward an edge of the current collector.

[0075] In some embodiments, the wrinkle removal tape is configured as a plurality of separate tapes disposed over the bare foil portions of the current collector for web coating applications.

[0076] The terms "a" and "an" do not imply a limitation of quantity, but denote the presence of at least one of the stated elements. The term "or" means "and / or" unless the context clearly indicates otherwise. When reference is made throughout this specification to "an aspect," this means that a particular element (e.g., a feature, structure, step, or property) described in connection with that aspect is included in at least one of the aspects described in this specification and may or may not be present in other aspects. It is understood that the described elements in the various aspects may be combined in any suitable manner.

[0077] When an element such as a layer, film, region, or substrate is described as lying "on" another element, it may lie directly on top of the other element, or there may be intervening elements. In contrast, when an element is described as lying "directly on" another element, there are no intervening elements.

[0078] Unless otherwise indicated herein, all examination standards are the most recent standard in force on the filing date of this application or, if priority is claimed, on the filing date of the earliest priority application in which the examination standard appears.

[0079] Unless otherwise defined, technical and scientific terms used in this document have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0080] Although the above disclosure has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes may be made and equivalent elements may be substituted without departing from the scope thereof. Furthermore, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from its essential scope. Therefore, it is intended that the present disclosure not be limited to the particular embodiments disclosed, but will include all embodiments falling within its scope.

Claims

[1] System for manufacturing electrodes, the system comprising: an upper roller press; a lower roller press separated from the upper roller press by a gap, the gap having a distance selected to accommodate a current collector, the current collector comprising a bare portion and a coated portion having an electrode active material having a first thickness thereon; and a wrinkle removal tape having a second thickness selected based on the first thickness to evenly distribute stress across the bare portion and the coated portion of the current collector during a calendering process to form a pressed electrode. [2] The system of claim 1, further comprising a tape guide roller and / or a tension roller configured to align the wrinkle removal tape with the bare portion of the current collector. [3] The system of claim 2, further comprising a servo system coupled to the tape guide roller and / or the tension roller, the servo system comprising a servo motor and one or more rollers configured to reposition the de-wrinkle tape to maintain alignment with the bare portion of the current collector. [4] The system of claim 1, wherein the wrinkle removal band comprises an upper wrinkle removal band disposed over an upper surface of the bare portion of the current collector. [5] The system of claim 1, wherein the wrinkle removal band comprises a lower wrinkle removal band disposed over a lower surface of the bare portion of the current collector. [6] The system of claim 1, wherein the wrinkle removal band is one of an upper wrinkle removal band disposed over an upper surface of the bare part of the current collector and a lower wrinkle removal band disposed over a lower surface of the bare part of the current collector, and the system further comprises a second wrinkle removal band that is the other of the upper wrinkle removal band and the lower wrinkle removal band. [7] The system of claim 1, wherein the second thickness of the wrinkle removal band is tapered. [8] The system of claim 7, wherein the wrinkle removal band is disposed over a top surface of the bare portion of the current collector, and the second thickness of the wrinkle removal band includes a positive taper that increases toward an edge of the current collector. [9] The system of claim 7, wherein the wrinkle removal band is disposed over a lower surface of the bare portion of the current collector, and the second thickness of the wrinkle removal band includes a positive taper that increases toward an edge of the current collector. [10] The system of claim 1, wherein the wrinkle removal belt is configured as a plurality of separate belts disposed over the bare portion of the current collector for web coating applications.

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