Electrode foil edge tensioning

Abstract

Aspects of the present disclosure include electrode calendering systems that utilize electrode foil edge tensioning to reduce calendering wrinkles and methods of making electrodes using the electrode calendering systems. An exemplary system includes a calendering module having a pair of calendering rollers separated by a gap. The gap includes a distance selected to receive the current collector. The current collector includes an exposed portion and a coated portion having an active electrode material having a first thickness thereon. The system includes an unwinding module upstream of a calendering module, a collector module downstream of the calendering module, and one or more idle rollers. A freewheeling roller of the one or more freewheeling rollers includes a tensioning sleeve having a second thickness selected based on the first thickness to over-tension an underlying portion of the current collector, the tensioning sleeve aligned with an exposed portion of the current collector.

Description

Technical Field

[0001] The present disclosure relates to battery cell manufacturing, and more particularly to an electrode calendaring system that utilizes electrode foil edge tensioning to reduce calendaring wrinkling. Background Art

[0002] Electrodes are widely used in a range of devices that store electrical energy, including primary (non-rechargeable) battery cells, secondary (rechargeable) battery cells, fuel cells, and capacitors. An ideal electrode needs to balance various energy storage properties, such as energy density, power density, maximum charge rate, internal leakage current, equivalent series resistance (ESR), charge-discharge cycle durability, high conductivity, and low tortuosity. Electrodes often include current collectors to supplement or otherwise improve these energy storage properties. The current collector can provide higher specific conductivity and can increase the available contact area to minimize the interfacial contact resistance between the electrode and its terminals.

[0003] The current collector is typically a sheet of conductive material to which the active electrode material is attached. Aluminum foil, aluminum alloys, copper alloys, stainless steel, and titanium foil are commonly used as current collectors for electrodes. In some electrode manufacturing processes, for example, a film containing activated carbon powder (i.e., the active electrode material) is attached to a thin aluminum or copper foil using an adhesive layer. In order to improve the interfacial bonding quality between the active electrode material film and the current collector, the combination of the film and the current collector is processed in a pressure laminator, such as a calender. This process is commonly referred to as calendering. Therefore, the manufacture of electrodes typically involves producing a film of active electrode material and laminating the film to the current collector. Summary of the Invention

[0004] In one exemplary embodiment, an electrode calendering system for manufacturing an electrode is provided that utilizes electrode foil edge tensioning to reduce calendering wrinkling. The roll-to-roller system includes a calendering module having a pair of calendering rollers separated by a gap. The gap includes a distance selected to accommodate a current collector. The current collector includes an exposed portion and a coated portion having a first thickness of active electrode material thereon. The system includes an unwinding module upstream of the calendering module, a collector module downstream of the calendering module, and one or more idle rollers located between the unwinding module and the collector module. An idle roller of the one or more idle rollers includes a tensioning sleeve having a second thickness selected based on the first thickness to over-tension a lower portion of the current collector. The tensioning sleeve is aligned with the exposed portion of the current collector.

[0005] In addition to one or more features described herein, in some embodiments, the calendering pressure generated during the calendering module is used to correct for excessive tension applied to the exposed portion of the current collector, thereby reducing wrinkling of the foil after calendering.

[0006] In some embodiments, the tensioning sleeve is secured to a corresponding idler roller of the one or more idler rollers using at least one of a press fit and an adhesive. In some embodiments, the tensioning sleeve is secured to a corresponding idler roller of the one or more idler rollers using one or more set screws. In some embodiments, the tensioning sleeve is secured to a corresponding idler roller of the one or more idler rollers using one or more leaf springs.

[0007] In some embodiments, the tensioning sleeve is tapered.

[0008] In some embodiments, the tensioning sleeve includes at least one of a patterned texture comprising one or more protrusions, one or more dimples, or one or more grooves.

[0009] In some embodiments, at least one of the line speed and the tension of the current collector is adjusted to tune the excess tension applied to the exposed portion of the current collector.

[0010] In some embodiments, one or more dancer rollers are positioned between the unwinder module and the collector module. In some embodiments, the tension of the current collector is adjusted by shifting the position of at least one of the one or more dancer rollers.

[0011] In another exemplary embodiment, a method for manufacturing an electrode is provided. The method includes providing a calendering module having a pair of calendering rollers separated by a gap. The gap includes a distance selected to accommodate a current collector. The current collector includes an exposed portion and a coated portion having a first thickness of active electrode material thereon. The method includes providing an unwinding module upstream of the calendering module, a collector module downstream of the calendering module, and one or more idle rollers located between the unwinder module and the collector module. An idle roller of the one or more idle rollers includes a tensioning sleeve having a second thickness selected based on the first thickness to over-tension a lower portion of the current collector. The tensioning sleeve is aligned with the exposed portion of the current collector.

[0012] In addition to one or more features described herein, in some embodiments, the calendering pressure generated during the calendering module is used to correct for excessive tension applied to the exposed portion of the current collector, thereby reducing wrinkling of the foil after calendering.

[0013] In some embodiments, the tensioning sleeve is secured to a corresponding idler roller of the one or more idler rollers using at least one of a press fit and an adhesive. In some embodiments, the tensioning sleeve is secured to a corresponding idler roller of the one or more idler rollers using one or more set screws. In some embodiments, the tensioning sleeve is secured to a corresponding idler roller of the one or more idler rollers using one or more leaf springs.

[0014] In some embodiments, an additional idler roller of the one or more idler rollers is located above the coated portion of the current collector.The additional idler roller may include an additional tensioning sleeve having a diameter 1 to 4 microns larger than the diameter of the additional idler roller.

[0015] In some embodiments, the tensioning sleeve includes at least one of a patterned texture comprising one or more protrusions, one or more dimples, or one or more grooves.

[0016] In some embodiments, at least one of the line speed and the tension of the current collector is adjusted to tune the excess tension applied to the exposed portion of the current collector.

[0017] In some embodiments, one or more dancer rollers are positioned between the unwind module and the collector module. In some embodiments, the tension of the current collector is adjusted by shifting the position of at least one of the one or more dancer rollers. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Additional features, advantages, and details appear, by way of example only, in the following detailed description, which refers to the accompanying drawings.

[0019] Figure 1 is a vehicle configured according to one or more embodiments;

[0020] Figure 2 is an exemplary configuration of an electrode calendaring system according to one or more embodiments;

[0021] Figure 3A According to one or more embodiments Figure 2 An exemplary configuration of an idler roller of an electrode calendaring system;

[0022] Figure 3B 、 3C and 3D illustrate a schematic diagram of a device according to one or more embodiments. Figure 3A An exemplary mounting configuration for a tensioning sleeve of an idler roller;

[0023] Figure 4A According to one or more embodiments Figure 2 An exemplary configuration of an idler roller of an electrode calendaring system;

[0024] Figure 4B 、 Figure 4C 、 Figure 4D and Figure 4E According to one or more embodiments, Figure 4A An exemplary profile configuration of a tensioning sleeve of an idler roller; and

[0025] Figure 5is a flow chart according to one or more embodiments. DETAILED DESCRIPTION

[0026] The following description is merely exemplary in nature and is in no way intended to limit the present disclosure, its application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0027] Electrode is usually combined with current collector to supplement or otherwise improve the energy storage characteristics of the final integrated device (e.g., battery). Current collector usually includes a conductive material sheet (e.g., aluminum foil, copper foil, etc.) to which the active electrode material is attached. In order to improve the quality of the interface bonding between the film of the active electrode material and the current collector, the combination of the film and the current collector is processed in a pressure laminator. Therefore, the manufacture of the electrode usually involves the production of the active electrode material film and laminating the film to the current collector (so-called calendering process).

[0028] Calendering can generally be defined as the compression of dry electrodes (the latter typically resulting from the coating and drying of electrode slurries) to reduce their porosity, improve particle contact, and enhance energy or power density. Conventional calendering processes have been used to improve various aspects of battery technology by providing, for example, higher conductivity, larger contact area, and lower contact resistance in electrodes. However, there are several challenges in optimizing the calendering process.

[0029] For example, one such challenge is the wrinkling defects that occur when rolling an electrode (e.g., a cathode) onto a current collector substrate (e.g., a foil substrate such as aluminum, stainless steel, and titanium) when targeting a lower porosity. Wrinkling defects (also known as uneven elongation) are found at the interface between the coated portion of the current collector (i.e., those portions with the pressed electrode film) and the uncoated portion (i.e., the exposed portion of the current collector) and are due to the different material properties and thicknesses of the electrode and substrate materials. These defects worsen as the resulting porosity decreases, meaning that relatively low-porosity electrodes themselves suffer from more prevalent wrinkling defects.

[0030] While there are several approaches to mitigate wrinkling defects, each has some tradeoffs. For example, a naive approach is to increase the porosity target, resulting in a proportional reduction in wrinkling defects, but with a reduction in electrode conductivity. Another approach is to completely cover the substrate so that there are no interfaces where wrinkling defects can occur. The tradeoff here is that the bare foil portions of the current collector (i.e., those portions not covered by active electrode material) are ideal for use as battery terminals, and simply removing the bare foil portions reduces battery efficiency.

[0031] This disclosure describes a novel electrode calendaring system that utilizes electrode foil edge tensioning to reduce calendaring wrinkling, and a method for manufacturing electrodes using the electrode calendaring system. Rather than increasing porosity targets or removing (or reducing) the bare foil portion of the electrode, the electrode calendaring system described herein is configured to intentionally overstretch the foil during the roll-to-roll drawing process. The foil edge pressure generated during the calendaring process is used to correct (reverse, undo, etc.) this overtensioning (rather than introducing new wrinkles), thereby reducing wrinkling in the foil after calendaring. In short, foil edge overtensioning creates a localized elongation that is evened out during calendaring. Although primarily referred to as "pre-tensioning" when referring to overtensioning schemes, in which the foil edge is pre-tensioned prior to calendaring, in some embodiments, foil edge overtensioning can occur after calendaring in a so-called post-tensioning scheme. Foil edge overtensioning can be ensured by adding tensioning sleeves to idler (or pull) rolls before or after the calendaring rolls, by controlling dancer rolls and line speed to tension the electrode, or by a combination of both.

[0032] Utilizing an electrode calendaring system with a foil edge tensioning scheme according to one or more embodiments provides several technical advantages over existing designs. Notably, the modified electrode manufacturing system and associated processes described herein can be used to produce electrodes that are free of (or greatly reduced in) wrinkling defects and have relatively improved elongation. Batteries constructed from electrodes that are free of wrinkles and have more uniform elongation provide a range of improved battery characteristics because these defects can reduce electrode integrity (e.g., wrinkles can result in poor adhesion between the coated electrode film and the current collector, resulting in relatively weak adhesion areas that are prone to delamination or peeling), increase resistance (wrinkles and thickness variations can create gaps or areas of reduced contact between the electrode material and the current collector that can hinder the flow of electrons). Increased degradation and reduced cycle life (electrodes with wrinkles and / or uneven elongation may experience increased stress and strain during charge-discharge cycles due to inconsistent mechanical properties, which may lead to accelerated degradation, cracking, or even electrode failure), increased thermal instability (wrinkles may trap electrolyte and inhibit heat dissipation, resulting in localized hot spots that may degrade the electrolyte), and reduced capacity and energy density (wrinkles and elongation defects may result in uneven thickness distribution across the electrode surface, and these unevenness may result in reduced active material utilization, reduced capacity, and compromised energy density in the battery). Other advantages are possible. For example, existing roll-to-roll processes can be modified in a somewhat simple manner to reduce wrinkle defects by incorporating a tensioning sleeve and / or by adjusting the line speed and dancer roll position without redesigning the main rolls / calendering rolls. Furthermore, reducing wrinkle and elongation defects as described herein eliminates the need for foil annealing and foil stiffening steps and the need to introduce ridges in the current collector, each of which is a technique commonly relied upon for defect mitigation but is known to weaken the foil. Furthermore, the annealing and foil stiffening steps are energy consuming and expensive.

[0033] According to an exemplary embodiment, the vehicle Figure 1 100. Vehicle 100 is shown in the form of an automobile having a body 102. Body 102 includes a passenger compartment 104 within which a steering wheel, front seats, and rear passenger seats (not separately shown) are located. Within body 102 are various components, including, for example, an electric motor 106 (shown as a projection beneath the front hood). Electric motor 106 is shown for ease of illustration and discussion only. It should be understood that the configuration, location, size, arrangement, etc. of electric motor 106 are not intended to be particularly limited, and that all such configurations (including multi-motor configurations) are contemplated within the present disclosure.

[0034] The electric motor 106 is powered via a battery pack 108 (shown by a projection near the rear of the vehicle 100). The battery pack 108 is shown for ease of illustration and discussion only. It should be understood that the configuration, location, size, arrangement, etc. of the battery pack 108 are not meant to be particularly limited, and all such configurations (including split configurations) are within the intended scope of the present disclosure. Furthermore, while the present disclosure is primarily discussed in the context of a battery pack 108 configured for use with the electric motor 106 of the vehicle 100, the aspects described herein may be similarly incorporated within any system (vehicle, building, or other) having an energy storage system (e.g., one or more battery packs or modules), and all such configurations and applications are within the intended scope of the present disclosure.

[0035] As will be described in detail herein, the battery pack 108 includes one or more battery cells having electrodes with enhanced edge quality (i.e., even elongation and reduced or eliminated wrinkles). In some embodiments, the electrode calendaring system is modified by incorporating a tensioning sleeve on an idler (or pull) roll before or after the calendaring roll, or by tensioning the electrode by controlling the dancer roll and line speed, or by a combination of both (see Figure 2 A variety of installation techniques are available (see Figure 3A 、 Figure 3B 、 Figure 3C and Figure 3D ) in combination with a tensioning sleeve. The design of the shape and profile of the tensioning sleeve itself can be customized for further optimization (see Figure 4A 、 Figure 4B 、 Figure 4C 、 Figure 4D and Figure 4E ).

[0036] Figure 2 1 shows an exemplary configuration of an electrode calendaring system 200 according to one or more embodiments. Figure 2As shown, the electrode calendaring system 200 can include a coated current collector 202 (itself made of a current collector foil and an electrode coating, not separately shown) that is transferred from an unwind module 204 to a current collector module 206 via a plurality of idler rollers 208 (also known as pulling rollers or positioning rollers). The number and position of the idler rollers 208 are illustrative only and are not meant to be particularly limiting.

[0037] The idler roller 208 guides the coated current collector 202 between a pair of calendering rollers 210 (also referred to as an upper roller press and a lower roller press) of a calendering module 212 (also referred to as a roller press system) for calendering. In some embodiments, the electrode calendering system 200 includes a feed module 214 located between the unwinding module 204 and the calendering module 212. In some embodiments, the electrode calendering system 200 includes a discharge module 216 located between the calendering module 212 and the collector module 206. In some embodiments, the electrode calendering system 200 may include a metering thickness module 218 located before or after the calendering module 212 (as shown).

[0038] In some embodiments, the feed module 214 and / or the discharge module 216 include one or more dancer rollers 220. The dancer rollers 220 can be displaced vertically and / or horizontally (e.g., actuated via a spring, lever, cam, and / or pneumatic device) to change the travel length of the coated current collector 202, thereby changing the amount of tension applied to the coated current collector 202. It should be understood that the electrode calendaring system 200 has been simplified for the sake of clarity and simplicity. The electrode calendaring system 200 can include any number of additional rollers (e.g., guide rollers, positioning rollers, dancer rollers, etc.) and other roll-to-roll equipment (e.g., monitoring equipment such as high-speed cameras, foil guide and tracking systems, support structures such as steel frames, etc.), and all of these configurations are within the intended scope of the present disclosure.

[0039] In some embodiments, coated current collector 202 comprises a current collector coated with an active electrode material (see Figure 3A Although not intended to be particularly limiting, the active electrode material may include, for example, various cathode or anode materials (depending on the requirements of the specific 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 rich manganese (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).

[0040] Similarly, the current collector (also referred to as mesh or bare foil) is not meant to be particularly limited, but may include, for example, conductive metal sheets such as aluminum foil, stainless steel, and titanium foil. Other materials are possible, such as, for example, semi-metals (e.g., tin, graphite), alloys of metals and / or semi-metals, conductive 2D meshes, conductive 3D meshes, conductive foams, etc.

[0041] In some embodiments, the calendering rollers 210 are positioned to apply pressure to the coated current collector 202. This process (referred to as calendering) is designed to improve the density, uniformity, and overall performance of the resulting pressed electrode (not shown separately) by compressing and compacting the electrode material onto a portion of the current collector. The calendering rollers 210 can be made of durable materials (e.g., steel) and can be manufactured to have precision surfaces (e.g., sub-10 micron tolerances) to ensure uniform pressure distribution. In some embodiments, the gap between the calendering rollers 210 can be adjusted by (e.g., hydraulically) moving one or two of the calendering rollers 210 to control the amount of pressure applied.

[0042] In some embodiments, the electrode calendering system 200 includes several control parameters, such as roller temperature (top and / or bottom), calendering pressure, gap distance, and line speed. In some embodiments, the roller temperature is at most 150 degrees Celsius, the pressure is at most 10 MPa, and the line speed is 110 meters per minute, although other calendering configurations are also within the contemplation of the present disclosure. In some embodiments, the gap between the calendering rollers 210 can be adjusted (hydraulically or otherwise) to the desired thickness of the pressed electrode.

[0043] In some embodiments, the line speed and / or tension of the electrode calendaring system 200 is adjusted to target a predetermined over-tensioning of the coated current collector 202. In some embodiments, the predetermined over-tensioning is an amount of over-tensioning that is known empirically (via, for example, a previous run of a roll-to-roll process) or predicted by simulation (via, for example, finite element analysis (FEA)) to achieve a wrinkle-free pressed electrode after calendaring. It has been observed that the line speed and / or tension required to achieve a wrinkle-free pressed electrode (i.e., after calendaring) will vary based on the load (e.g., mg / cm2) and density of the electrode material, the material selected for the current collector, and the target thickness of the pressed electrode. The line speed and / or tension may also vary based on additional factors, including, but not limited to, electrode formulation, surface roughness, tensile properties, and the like.

[0044] The tension of the electrode calendaring system 200 can be adjusted by moving one or more dancer rollers 220 vertically and / or horizontally, as described herein. For example, in some embodiments, the linear speed of the electrode calendaring system 200 is 10 m / s and the tension of the electrode calendaring system 200 is 22 kg, but the tension and linear speed can be varied according to the needs of the current configuration (e.g., electrode thickness, composition, etc.). All of these configurations are within the intended scope of the present disclosure. In some embodiments, the degree of deformation (pre-tensioning) can be observed (i.e., can be empirically checked) for multiple tension and linear speed combinations for known electrode configurations.

[0045] Figure 3A According to one or more embodiments, Figure 2 An exemplary configuration of the idler roller 208 of the electrode calendaring system 200 is shown. Figure 3A As shown, the idle roller 208 (which itself may represent Figure 2 Any one or more of the idler rollers 208 in the apparatus may include one or more tensioning sleeves 302. In some embodiments, the additional thickness of the tensioning sleeves 302 on the idler rollers 208 is used to over-tension the lower portion of the coated current collector 202.

[0046] In some embodiments, the coated current collector 202 includes one or more bare foil portions 304 and one or more coated portions 306, and the tensioning sleeve 302 is positioned to align with the bare foil portions 304. In this manner, the tensioning sleeve 302 can be utilized to over-tension the bare foil portions 304 of the coated current collector 202. Advantageously, this over-tensioning of the bare foil portions 304 of the coated current collector 202 is fully or partially recovered during the calendaring process (see FIG. Figure 2 ), because calendaring naturally applies asymmetric stresses to the bare foil portion 304 and the coated portion 306 of the coated current collector 202.

[0047] The number of tensioning sleeves 302 can be adjusted according to the number of bare foil portions 304 of the coated current collector 202. For example, for single-sided or double-sided coating applications, a pair of tensioning sleeves 302 can be positioned to cover both exposed edges of the coated current collector 202. In a roller coating application (as shown), any number of tensioning sleeves 302 can be positioned to accommodate any number of coating rollers (as shown, three rollers, although 4, 5, 10 rollers, etc. are possible). In some embodiments, the number of tensioning sleeves 302 can be greater than the number of bare foil portions 304 of the coated current collector 202. In particular, one or more additional tensioning sleeves 302 can be positioned, for example, to help prevent warping of the electrode web (coated current collector 202). In some embodiments, three tensioning sleeves 302 can be positioned so that the middle tensioning sleeve is placed on the coated portion 306 of the coated current collector 202. In this case, the diameter of the intermediate tensioning sleeve (and any other sleeves of the tensioning sleeve 302) can be several microns (e.g., 1 to 4 microns) larger than the pulling roller (e.g., idler roller 208), thereby allowing the intermediate tensioning sleeve to apply additional traction to the corresponding area of the coated current collector 202. In this way, the overall warping of the electrode web can be reduced.

[0048] Figure 3B 、 Figure 3C and Figure 3D According to one or more embodiments, Figure 3A 2. An exemplary mounting configuration of the tensioning sleeve 302 for the idler roller 208. Figure 3B Press fit and / or adhesive mounting options are shown. Figure 3C A set screw installation scheme is shown. Figure 3D A leaf spring mounting solution is shown. Regardless of the configuration, in some embodiments, the tensioning sleeve 302 can be dynamically adjusted. For example, adjustment can be performed using smart materials, adjustable elliptical springs, expansion of the sleeve by heating or cooling the sleeve, etc.

[0049] like Figure 3B As shown, tensioning sleeve 302 can be secured to idler roller 208 using a press fit and / or adhesive 308. Press fit and / or adhesive 308 are not meant to be particularly limited and can be selected, for example, based on the material, thickness, and / or other characteristics of tensioning sleeve 302 and / or idler roller 208. For example, press fit and / or adhesive 308 can include a polyurethane blend for metal-to-polymer applications.

[0050] like Figure 3C As shown, the tensioning sleeve 302 may be secured to the idler roller 208 using one or more set screws 310. The number and type of set screws 310 are not meant to be particularly limited, and all such configurations are within the contemplated scope of the present disclosure.

[0051] like Figure 3D As shown, the tensioning sleeve 302 can be secured to the idler roller 208 using one or more leaf springs 312. The number and type of leaf springs 312 are not intended to be particularly limited, and all such configurations are within the contemplated scope of the present disclosure. Advantageously, the tensioning sleeve 302 can be dynamically adjusted in this configuration by adjusting the tension in the leaf springs 312.

[0052] Figure 4A According to one or more embodiments, Figure 2 1 and 2. An exemplary configuration of the idler roll 208 of the electrode calendaring system 200 is shown. Figure 4B 、 Figure 4C 、 Figure 4D and Figure 4E A method for Figure 4A Detailed view 400 of FIG. 4 illustrates an exemplary profile configuration of the tensioning sleeve 302 .

[0053] Figure 4B A relatively rapid taper 402 of the tensioning sleeve 302 is shown. As used herein, a relatively rapid taper means a taper that is accomplished within less than 20% or 10% of the width of the tensioning sleeve 302. In this manner, the tensioning sleeve 302 provides a flat profile suitable for applications having a consistent electrode coating thickness.

[0054] Figure 4C A relatively slow taper 404 of the tensioning sleeve 302 is shown. As used herein, a relatively slow taper means a taper that occurs over at least 50%, 60%, 75%, 90%, or 100% (as shown) of the width of the tensioning sleeve 302. In this manner, the tensioning sleeve 302 provides a concave (or alternatively, convex) profile that is suitable for applications where the electrode coating thickness increases (or decreases) along the width of the coated current collector 202.

[0055] Figure 4D Shown is a patterned texture 406 rather than Figure 4B and Figure 4C3. The tensioning sleeve 302 is shown with a smooth texture. The patterned texture 406 can include any number of protrusions and / or recesses arranged in any desired configuration, and all such configurations are within the contemplation of the present disclosure. In some embodiments, the patterned texture 406 is uniform across the tensioning sleeve 302 (within tool limitations). In some embodiments, the patterned texture 406 is asymmetrical across the tensioning sleeve 302. For example, the number, size, location, spacing, and / or orientation of the protrusions and / or recesses of the patterned texture 406 can be varied across the tensioning sleeve 302 to address any desired over-tensioning geometry, and all such configurations are within the contemplation of the present disclosure.

[0056] Figure 4E The tensioning sleeve 302 is shown having a plurality of grooves 408 disposed thereon. The number, size, location, spacing, and / or orientation of the grooves 408 can be varied as desired to address any desired over-tensioning geometry, and all such configurations are within the contemplated scope of the present disclosure.

[0057] Although Figure 4B 、 Figure 4C 、 Figure 4D and Figure 4E The exemplary configuration of the tensioning sleeves 302 shown in FIG is depicted as having substantially the same width, but this is for convenience only. The tensioning sleeves 302 of the idler roller 208 do not need to have the same width. Similarly, the tensioning sleeves 302 do not need to have the same thickness and / or taper, and all such configurations are within the contemplation of the present disclosure. Furthermore, any tapering (if any) may be symmetrical or limited to a single side of the tensioning sleeve 302 (e.g., outer edge, inner edge).

[0058] In some embodiments, the thickness of the tensioning sleeve 302 for a given application is selected to target a predetermined over-tension of the coated current collector 202. In some embodiments, the predetermined over-tension is the amount of over-tension that is empirically known (e.g., via a previous run of a roll-to-roll process) or predicted by simulation (e.g., via finite element analysis (FEA)) to achieve a wrinkle-free pressed electrode after calendaring. It has been observed that the thickness required to achieve a wrinkle-free pressed electrode (i.e., after calendaring) will vary based on the loading (e.g., mg / cm2) and density of the electrode material, the material selected for the current collector, and the target thickness of the pressed electrode. Furthermore, the tape thickness can be selected based on any of a number of design and / or target parameters, such as bending strength, strain, elongation, electrode thickness, and / or yield strength. The tape thickness can also vary based on additional factors, including but not limited to electrode formulation, surface roughness, tensile properties, etc. In some embodiments, for example, the tensioning sleeve 302 can be formed to a thickness of 50 to 100 microns, such as 70 microns, but other thicknesses are also within the contemplated scope of the present disclosure. In some embodiments, the tensioning sleeve 302 can be placed on the idler roller 208 by wrapping the material around the idler roller 208. In some embodiments, the tensioning sleeve 302 is wrapped around the idler roller 208 at a wrap angle greater than 90 degrees.

[0059] The tensioning sleeve 302 can be made of a material having known elasticity selected according to the designed calendering pressure. For example, although not particularly limiting, the tensioning sleeve 302 can be made of a metal such as aluminum, stainless steel, steel alloy, etc., or a polymer and / or elastomer such as silicon mixed with a polymer such as polypropylene, a thermoplastic polymer such as polyethylene terephthalate (PET) and polyvinylidene fluoride (PVDF), polyethylene (PE) including low-density polyethylene (LDPE) and high-density polyethylene (HDPE), polytetrafluoroethylene (PTFE), polyamide such as nylon, synthetic rubber such as neoprene, a hybrid material with glass fiber, silica, etc., a polymer and metal laminate with rubber, etc.

[0060] Now refer to Figure 5 , generally shows a flow chart 500 for manufacturing an electrode using an electrode calendaring system that utilizes electrode foil edge tensioning to reduce calendaring wrinkling, according to an embodiment. Figure 1-4E Flowchart 500 is described and may include Figure 5 Additional steps not depicted in the . Although depicted in a specific order, Figure 5 The blocks depicted in the drawings may be rearranged, subdivided, and / or combined.

[0061] At block 502, the method includes providing a calendering module having a pair of calendering rollers separated by a gap. The gap comprises a distance selected to accommodate a current collector. The current collector comprises a bare portion and a coated portion having a first thickness of active electrode material thereon.

[0062] At block 504, the method includes providing an unwind module upstream of the calendering module.At block 506, the method includes providing a collector module downstream of the calendering module.

[0063] At block 508, the method includes providing one or more idler rollers positioned between the unwind module and the collector module. In some embodiments, one of the one or more idler rollers includes a tensioning sleeve having a second thickness. In some embodiments, the second thickness is selected based on the first thickness to overstretch a lower portion of the current collector. In some embodiments, the tensioning sleeve is aligned with an exposed portion of the current collector (i.e., the exposed portion is overstretched).

[0064] In some embodiments, the calendering pressure generated during the calendering module is used to correct for excess tension applied to the exposed portion of the current collector, thereby reducing wrinkling of the calendered foil.

[0065] In some embodiments, the tensioning sleeve is secured to a corresponding idler roller of the one or more idler rollers using at least one of a press fit and an adhesive. In some embodiments, the tensioning sleeve is secured to a corresponding idler roller of the one or more idler rollers using one or more set screws. In some embodiments, the tensioning sleeve is secured to a corresponding idler roller of the one or more idler rollers using one or more leaf springs.

[0066] In some embodiments, the tensioning sleeve is tapered.

[0067] In some embodiments, the tensioning sleeve includes a sleeve having one or more protrusions (see Figure 4D ), one or more pits (see Figure 4D ) or one or more grooves (see Figure 4E )'s patterned textures.

[0068] In some embodiments, at least one of the line speed and the tension of the current collector is adjusted to tune the excess tension applied to the exposed portion of the current collector.

[0069] In some embodiments, the method includes providing one or more dancer rollers between the unwind module and the collector module. In some embodiments, the tension of the current collector is adjusted by shifting the position of at least one of the one or more dancer rollers.

[0070] The terms "a" and "an" do not indicate a limitation of quantity, but rather indicate the presence of at least one of the referenced item. Unless the context clearly indicates otherwise, the term "or" means "and / or". References to "aspects" throughout this specification mean that a particular element (e.g., a feature, structure, step, or characteristic) described in conjunction with that aspect is included in at least one aspect described herein and may or may not be present in other aspects. In addition, it should be understood that the described elements may be combined in any suitable manner in the various aspects.

[0071] When an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present.

[0072] Unless otherwise indicated herein, all test standards are the most current standards in effect as of the filing date of this application, or, if priority is claimed, the filing date of the earliest priority application in which the test standards appear.

[0073] Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0074] Although the above disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope thereof. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the basic scope of the present disclosure. Therefore, it is intended that the present disclosure is not limited to the particular embodiments disclosed, but is intended to include all embodiments falling within its scope.

Claims

1. A roll-to-roll system for manufacturing an electrode, the system comprising: a calendering module comprising a pair of calendering rollers separated by a gap, the gap comprising a distance selected to accommodate a current collector comprising a bare portion and a coated portion having an active electrode material thereon at a first thickness; an unwinding module upstream of the calendering module; a collector module downstream of the calendering module; as well as one or more idler rollers positioned between the unwind module and the collector module; Wherein, an idle roller of the one or more idle rollers includes a tensioning sleeve, the tensioning sleeve including a second thickness selected based on the first thickness to over-tension a lower portion of the current collector, the tensioning sleeve being aligned with an exposed portion of the current collector.

2. The roll-to-roll system according to claim 1, wherein: The calendering pressure generated during the calendering module is used to correct excessive tension applied to the exposed portion of the current collector, thereby reducing wrinkling of the calendered foil. 3 . The roll-to-roll system of claim 1 , wherein the tensioning sleeve is secured to a corresponding one of the one or more idler rollers using at least one of a press fit and an adhesive.

4. The roll-to-roll system of claim 1 , wherein the tensioning sleeve is secured to a corresponding idler roller of the one or more idler rollers using one or more set screws.

5. The roll-to-roll system of claim 1, wherein the tensioning sleeve is secured to a corresponding idler roller of the one or more idler rollers using one or more leaf springs.

6. The roll-to-roll system of claim 1 , wherein the tensioning sleeve is tapered.

7. The roll-to-roll system of claim 1, wherein the tensioning sleeve comprises at least one of a patterned texture comprising one or more protrusions, one or more dimples, or one or more grooves.

8. The roll-to-roll system of claim 1, wherein at least one of a linear velocity and a tension of the current collector is adjusted to tune the over-tension applied to the exposed portion of the current collector.

9. The roll-to-roll system of claim 8, further comprising one or more dancer rollers positioned between the unwind module and the collector module.

10. The roll-to-roll system of claim 9, wherein the tension of the current collector is adjusted by shifting the position of at least one of the one or more dancer rollers.

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