Self-supporting electrode film for dry electrode manufacturing

Abstract

An apparatus for manufacturing electrodes for an energy storage device includes at least one laminator for simultaneously laminating two self-supporting electrode films on both sides of a current collector, and a pair of mill lines each operable to produce the two films and simultaneously feed the two films to the laminator. Each mill line may include at least one press including a work roll horizontally disposed for pressing a powder mixture into each of the films, and at least one press including a work roll (typically vertically disposed) for reducing the thickness of each of the films. The apparatus may include a mill line expansion module insertable into the mill line and having at least one additional press including a work roll for reducing the thickness of each of the films and controlling other major parameters. The films may have an elongation of less than 4% and a tensile strength of less than 250 kPa.

Description

Technical Field

[0001] Cross - reference to related applications None applicable

[0002] Description of research and development funded by the federal government None applicable

Background Art

[0003] 1. Technical field

[0004] This disclosure generally relates to the manufacture of energy storage devices such as Li - ion batteries, and more specifically to dry processes for the manufacture of electrodes for energy storage devices.

[0005] 2. Related art

[0006] Due to the increasing demand for inexpensive energy storage devices, various methods for manufacturing electrodes have been proposed. Among these, in particular, there are so-called "dry" processes that can manufacture self-supporting electrode films while avoiding the costs and drying times associated with solvents and aqueous solutions typically used in slurry coating and extrusion processes. After the self-supporting electrode film is formed, it is laminated onto a current collector to form an electrode. Although there have been several attempts to devise a continuous process that performs both the generation of the self-supporting electrode film and the lamination of the self-supporting electrode film onto the current collector (see, for example, German Patent Application Publication DE 10 2017 208 220), the success of such processes has been limited, partly due to the difficulty in producing a uniform electrode film and handling the self-supporting electrode film without damaging it. This difficulty is particularly pronounced in the case of thinner electrode films, or less flexible electrode films made from materials such as lithium nickel manganese cobalt oxide (NCM), lithium nickel cobalt aluminum oxide (NCA), lithium iron phosphate (LFP), graphite, and silicon, which may be more difficult to work with than activated carbon, for example. [Overview of the Initiative]

[0007] This disclosure intends to provide various apparatuses and methods, as well as related products, for overcoming the aforementioned drawbacks associated with the related technologies. One embodiment of the embodiments of this disclosure is an apparatus for manufacturing electrodes for an energy storage device. The apparatus may comprise at least one laminator for simultaneously laminating two self-supporting electrode films on both sides of a current collector, and a pair of mill lines, each capable of producing the two self-supporting electrode films and simultaneously feeding the two self-supporting electrode films to the laminator. Each mill line may comprise at least one first press including a horizontally positioned work roll for pressing a powder mixture into each of the self-supporting electrode films, and at least one second press including a work roll (typically positioned vertically) for reducing the thickness of each self-supporting electrode film.

[0008] The apparatus may include a mill line extension module. The mill line extension module may be insertable into one of the pair of mill lines and may have at least one additional second press, including a work roll (typically positioned vertically) for reducing the thickness of each of the self-supporting electrode films. Generally, the number of presses can be directly related to the final electrode film thickness, porosity, and density, and the corresponding mechanical strength of the film, e.g., fracture, elongation, and tensile strength, as well as the mill line speed. By employing a modular system rather than having a fixed number of presses, the apparatus can accommodate these parameters for various material types with different electrode specifications.

[0009] Each of the mill lines may include one or more conveyors arranged to support each of the self-supporting electrode films as they are fed from at least one second press of the mill line to the laminator. The one or more conveyors may be arranged to support each of the self-supporting electrode films as they are fed from the first of the at least one second presses of the mill line to the second of the at least one second presses. The speed of the one or more conveyors between the at least one second press of the mill line and the laminator may be controlled to be different from the speed of the one or more conveyors between the first of the at least one second presses of the mill line and the second of the at least one second presses. The one or more conveyors may be further arranged to support each of the self-supporting electrode films as they are fed from at least one first press of the mill line to at least one second press. The conveyor speeds between each stage, including between the first press and one of the second presses, between any adjacent second presses, and between the second press and the laminator, may be controlled differently. Each mill line may be equipped with one or more tension sensors positioned to measure the tension of the self-supporting electrode film. The speeds of one or more conveyors in the mill line and / or the speeds of the work rolls of at least one second press in the mill line may be controlled based on the measured tension, for example, to prevent film breakage. The one or more conveyors may include at least one vacuum conveyor.

[0010] Another embodiment of the embodiments of the present disclosure is a method for manufacturing electrodes for an energy storage device. The method may comprise the steps of: providing the apparatus described above; preparing a first powder mixture having an electrode active material and a fibrillable binder; fibrillating the fibrillable binder in the first powder mixture by subjecting the first powder mixture to a shear force; pressing the first powder mixture into a first self-supporting electrode film using the at least one first press of the first mill line of the pair of mill lines; reducing the thickness of the first self-supporting electrode film using the at least one second press of the first mill line; and laminating the first self-supporting electrode film onto the first side of a current collector using the at least one laminator.

[0011] The method may include the steps of: preparing a second powder mixture having an electrode active material and a fibrillable binder; fibrillating the fibrillable binder in the second powder mixture by subjecting the second powder mixture to a shear force; pressing the second powder mixture into a second self-supporting electrode film using at least one first press of the second mill line of the pair of mill lines; reducing the thickness of the second self-supporting electrode film using at least one second press of the second mill line; and simultaneously with the lamination of the first self-supporting electrode film onto the first side of the current collector, laminating the second self-supporting electrode film onto the second side of the current collector opposite the first side using at least one laminator.

[0012] Another embodiment of the embodiments of the present disclosure is a method for manufacturing electrodes for an energy storage device. The method may comprise the steps of: preparing a first powder mixture having an electrode active material and a fibrillable binder; fibrillating the fibrillable binder in the first powder mixture by subjecting the first powder mixture to a shear force; preparing a second powder mixture having an electrode active material and a fibrillable binder; fibrillating the fibrillable binder in the second powder mixture by subjecting the second powder mixture to a shear force; and simultaneously producing a first self-supporting electrode film from the first powder mixture and a second self-supporting electrode film from the second powder mixture using a pair of mill lines, each of which mill lines has at least one first press including a horizontally positioned work roll for pressing the respective powder mixtures into the respective self-supporting electrode films, and at least one second press including a (typically vertically positioned) work roll for reducing the thickness of the respective self-supporting electrode films. The method may further include, following the step of generating the first and second self-supporting electrode films, feeding the first and second self-supporting electrode films from their respective mill lines to a laminator, thereby laminating the first and second self-supporting electrode films on both sides of the current collector.

[0013] The method may include a step of using one or more conveyors to support the first self-supporting electrode film as it is fed from each of the mill lines to the laminator. The method may include a step of using one or more conveyors to support the first self-supporting electrode film as it is fed from the first of the at least one second presses of each mill line to the second of the at least one second presses. The method may include a step of controlling the speed of the one or more conveyors between each of the mill lines and the laminator to be different from the speed of the one or more conveyors between the first of the at least one first presses and the second of the at least one first presses of each mill line. The method may include a step of using one or more conveyors to support the first self-supporting electrode film as it is fed from the at least one first press to the at least one second press on each mill line. The method may include a step of controlling the conveyor speed to be different between each step, including between the first press and one of the second presses, between any adjacent second presses, and between the second press and the laminator. The method may include a step of measuring the tension of the first self-supporting electrode film and controlling the speed of the one or more conveyors and / or the speed of the work rolls of the at least one second press based on the measured tension to prevent, for example, film breakage. The one or more conveyors may include at least one vacuum conveyor.

[0014] Another embodiment of the embodiments of the present disclosure is a self-supporting electrode film. The self-supporting electrode film may comprise an electrode active material and a fibrillable binder. The mechanical elongation of the self-supporting electrode film may be less than 4%. The mechanical elongation of the self-supporting electrode film may be less than 2%. The mechanical tensile strength of the self-supporting electrode film may be greater than 450 kPa. The porosity of the self-supporting electrode film may be less than 32%. [Brief explanation of the drawing]

[0015] These and other features and advantages of the various embodiments disclosed in this specification will be better understood with reference to the following description and drawings, in which like numerals refer to like parts throughout.

[0016] [Figure 1] An apparatus for manufacturing an electrode for an energy storage device is shown.

[0017] [Figure 2] A partial view of an apparatus in which a mill line expansion module is inserted into its mill line is shown.

[0018] [Figure 3] An operation flow for manufacturing an electrode for an energy storage device is shown.

[0019] [Figure 4] An exemplary sub - operation flow of step 330 in FIG. 3 is shown.

[0020] [Figure 5] Active material loading according to the film thickness for an activated dry NCM811 electrode is shown.

[0021] [Figure 6] C - rate performance of wet vs. activated dry NCM811 electrodes is shown.

Embodiments for Carrying Out the Invention

[0022] This disclosure encompasses apparatus for manufacturing electrodes for energy storage devices, as well as various embodiments of the manufacturing method and intermediate and final products thereof. In relation to the accompanying drawings, the detailed description below is intended as a description of several currently contemplated embodiments and is not intended to represent the only form in which the disclosed invention may be developed or utilized. This description describes the functions and features in relation to the exemplary embodiments. However, it should be understood that identical or equivalent functions may be achieved by different embodiments which are similarly intended to be included within the scope of this disclosure. It should be further understood that the use of related terms such as First, Second, etc., is used simply to distinguish one subject from another, without necessarily requiring or implying any actual such relationship or order between such subjects.

[0023] FIG. 1 shows an apparatus 100 for manufacturing electrodes for energy storage devices such as Li-ion batteries, solid-state batteries, Li-ion capacitors (LICs), or ultracapacitors. The final energy storage device may comprise one or more electrodes assembled by laminating a first self-supporting electrode film 10a and a second self-supporting electrode film 10b on both sides of a current collector 20 such as an aluminum metal sheet in the case of the cathode electrode films 10a, 10b, or a copper metal sheet in the case of the anode electrode films 10a, 10b. The apparatus 100 may comprise at least one laminator 110 for simultaneously laminating two self-supporting electrode films 10a, 10b on both sides of the current collector 20. The laminator 110 may have, for example, work rolls 112-1, 112-2 arranged horizontally as shown, although vertical arrangements are also contemplated. The apparatus 100 may further comprise a pair of mill lines 120a, 120b (e.g., arranged in the wings of the apparatus 100) operable to each generate two self-supporting electrode films 10a, 10b and feed them simultaneously to the laminator 110. The laminator 110 may then laminate the two self-supporting electrode films 10a, 10b on either side of the current collector 20 when unwound from the first spool 130 and then wound onto the second spool 140 (or alternatively sent to a cutter) together with the laminated films 10a, 10b. By the apparatus 100 and associated methods described herein, efficient handling of the relatively thin self-supporting electrode films 10a, 10b (e.g., less than 200 μm or less than 100 μm), and / or even those formed from less flexible materials (e.g., battery active materials) such as NCM, NCA, LFP, graphite, and silicon, which enable the manufacture of a wide variety of energy storage devices for different purposes, may be enabled. In some embodiments, as described in more detail below, the apparatus 100 may have a modular design that allows the same apparatus 100 to be used to efficiently manufacture electrodes for energy storage devices having different specifications as needed.

[0024] Depending on the specific application of the energy storage device to be manufactured, the dry powder mixtures 12a and 12b used to produce the self-supporting electrode films 10a and 10b may have various formulations and may be produced according to various methods. Several exemplary dry powder formulations and methods that may be used to produce the dry powder mixtures 12a and 12b are described in the inventor's own patents and patent applications, including U.S. Patent No. 10,069,131 entitled "Electrode for Energy Storage Devices and Method of Making Same," U.S. Patent Application Publication 2020 / 0388822 entitled "Dry Electrode Manufacture by Temperature Activation Method," U.S. Patent Application Publication 2022 / 0077453 entitled "Dry Electrode Manufacture with Lubricated Active Material Mixture," U.S. Patent Application No. 17 / 097,200 entitled "Dry Electrode Manufacture with Composite Binder," and U.S. Patent Application No. 17 / 492,458 entitled "Dry Electrode Manufacture for Solid State Energy Storage Devices," the entirety of each of these disclosures is fully incorporated herein by reference. Typically, since the first and second self-supporting electrode films 10a and 10b will be arranged on the same current collector 20 by the apparatus 100, both the dry powder mixtures 12a and 12b will be formulated and produced in the same manner (and therefore, in practice, may be divided, for example, from the same manufacturing batch).

[0025] Each of the mill lines 120a, 120b may be provided with at least one first press 122a, 122b for pressing one of the powder mixtures 12a, 12b into their respective self-supporting electrode films 10a, 10b. Referring to mill line 120a as an example (in the case of mill line 120b, the equivalent reference number uses the letter "b" instead of "a"), the first press 122a may include horizontally positioned work rolls 123a-1, 123a-2, as shown, such that the powder mixture 12a can be poured (e.g., from a powder feeding conveyor 13a) onto the top of the work rolls 123a-1, 123a-2 and discharged from the bottom therefrom in the form of a continuous film subjected to pressure and heat by the work rolls 123a-1, 123a-2. For this purpose, the work rolls 123a-1 and 123a-2 of the first press 122a may have elevated surface temperatures (e.g., higher than 70°C). Advantageously, the work rolls 123a-1 and 123a-2 may be controlled to rotate at the same speed relative to each other, such that the gap between them can be freely adjusted, affecting the film density and porosity as desired for the specific material and application. In this regard, it should be noted that if the powder mixture 12a is produced by one of the exemplary methodologies referenced above, for example, by subjecting the powder mixture 12a to shear force using a jet mill, it may be unnecessary for the first press 122a to generate a shear effect through the operation of the work rolls 123a-1 and 123a-2 at different speeds.

[0026] Each of the mill lines 120a, 120b may further comprise at least one second press 124a, 124b for reducing the thickness of their respective self-supporting electrode films 10a, 10b. Referring again to mill line 120a as an example, the second press 124a may include work rolls 125a-1, 125a-2 that are typically (but not necessarily) arranged vertically as shown. Similar to the work rolls 123a-1, 123a-2 of the first press 122a, the work rolls 125a-1, 125a-2 of the second press 124a may have elevated surface temperatures (e.g., higher than 70°C) and may be controlled to rotate at the same speed relative to each other, with the gap between the work rolls 125a-1, 125a-2 freely adjustable as desired. Although only a single second press 124a is shown in Figure 1, it is intended that any number of second presses 124a may be provided in a row, each further reducing the thickness of the self-supporting electrode film 10a through the application of heat and pressure (for example, the gap between the work rolls 125a-1, 125a-2 in contact with the film 10a and the work rolls 125a-1, 125a-2 becomes successively smaller with each second press 124a) until a desired film thickness for a given application is achieved. To best suit manufacturing operations that use only a single second press 124a, 124b in each mill line 120a, 120b, such as when producing relatively thick self-supporting electrode films 10a, 10b, it may be most advantageous for each mill line 120a, 120b to include only a single second press 124a, 124b as part of the foundation of the apparatus 100 (as shown in Figure 2, the apparatus 100 is expandable using one or more mill line expansion modules 150). Along the same line, in some implementations, the foundation of each mill line 120a, 120b may include only one or more first presses 122a, 122b, and not any second press 124a, 124b.

[0027] As newer applications for energy storage devices require electrodes made from thinner self-supporting electrode films 10a, 10b, and as the potential of active materials comes to include materials that produce less flexible and more fragile self-supporting electrode films 10a, 10b, conventional roll-to-roll processing and methods may become unsuitable for handling the self-supporting electrode films 10a, 10b without breakage. Therefore, in order to better support each self-supporting electrode film 10a, 10b as it passes through its respective mill lines 120a, 120b toward the laminator 110 (the self-supporting electrode films 10a, 10b will then be supported by a more robust current collector 20 and will no longer be self-supporting), each mill line 120a, 120b may be equipped with one or more conveyors 126a, 126b, such as vacuum conveyors. Referring to mill line 120a as an example, one or more conveyors 126a may be arranged to support the self-supporting electrode film 10a at any of various positions, including, for example, i) when the self-supporting electrode film 10a is fed from the second press 124a of mill line 120a to the laminator 110, ii) when the self-supporting electrode film 10a is fed from the first of the second presses 124a to the second of the second presses 124a, and / or iii) when the self-supporting electrode film 10a is fed from the first press 122a to the second press 124a. The speed of the conveyor 126a may be controlled according to the thickness and tension of the self-supporting electrode film 10a at each particular position, which may be determined by the arrangement of the presses 122a, 124a and their roller speeds, as well as the granule laminator 110. For example, the speed of the conveyor 126a between the second press 124a and the laminator 110 may be controlled differently from the speed of the conveyor between subsequent second presses 124a, which in turn may be different from the speed of the conveyor between the first press 122a and the second press 124a. In practice, the speed of the conveyor 126a may be controlled in a cascading manner, where the final laminator speed 110 determines the speed at each upstream position of each mill line 120a, 120b.As feedback to the control process, each mill line 120a, 120b may be equipped with one or more tension sensors 128a, 128b positioned to measure the tension on the self-supporting electrode films 10a, 10b. Load cells or other proximity sensors may be employed to maintain optimal tension control by adjusting the rotational speed of the conveyors and work rolls. To enable the lamination speed to remain constant and prevent tearing of the films 10a, 10b, the variable speed and / or speed ratio of one or more conveyors 126a, 126b may be controlled so that the speed between presses is appropriately matched based on the tension measured using any of a variety of algorithms, including machine learning models.

[0028] Figure 2 shows a partial view of the apparatus 100 with the mill line extension module 150 inserted into its mill line 120a. The mill line extension module 150 may include at least one additional second press 154a for reducing the thickness of each self-supporting electrode film 10a, 10b (in this case, electrode film 10a as shown). As shown, for example, the mill line 120a of the base apparatus 100 may include a single second press 124a, and the mill line extension module 150 may introduce one or more additional second presses 154a (two additional second presses 154a as shown). The additional second presses 154a may be insertable into the mill line 120a, for example, immediately before the second press 124a of the base apparatus 100. (Note that if the mill line 120a does not include the second press 124a, the additional second press 154a introduced by the mill line extension module 150 may be the only thickness reduction press in the apparatus 100.) The dashed arrow in Figure 2 shows one possible insertion procedure, in which the first press 122a is moved further away from the laminator 110 (to the left in Figure 2), and the mill line extension module 150 is inserted into the space created thereby (up in Figure 2), and the dashed line shows the mill line extension module 150 before being inserted into the mill line 120a.

[0029] Similar to the second presses 124a, 124b of each mill line 120a of the base device 100, each additional second press 154a introduced by the mill line extension module 150 may include work rolls 155a-1, 155a-2 arranged vertically (but not necessarily) as typically shown. The work rolls 155a-1, 155a-2 of each additional second press 154a may have elevated surface temperatures (e.g., higher than 70°C) and may be controlled to rotate at the same speed relative to each other, with the gap between the work rolls 155a-1, 155a-2 freely adjustable as desired. The mill line extension module 150 is intended to further include one or more additional conveyors 156a that can be inserted between the conveyors 126a of the mill line 120a as shown. The millline extension module 150 may further include one or more additional tension sensors 158a arranged to measure the tension on the self-supporting electrode film 10a as it passes (e.g., before and after) an additional second press 154a of the millline extension module 150. The additional conveyor 156a and additional tension sensors 158a may be connected to the same speed control system as the conveyor 126a and tension sensors 128a of the base device 100. Note that the millline extension module 150 may be designed symmetrically for insertion into millline 120b rather than millline 120a as shown (and equivalent reference numbers using the letter "b" instead of "a" may be referred to in this case, but these are not shown separately).

[0030] The mill line expansion module 150 allows the same apparatus 100 to be easily customized for different manufacturing operations with different specifications for the energy storage devices to be produced. Manufacturers of energy storage devices made using relatively thick self-supporting electrode films 10a, 10b may use only the base apparatus 100 which does not have a mill line expansion module 150 in each mill line 120a, 120b, or which has only a single mill line expansion module 150, while manufacturers that need to produce thinner self-supporting electrode films 10a, 10b may insert several mill line expansion modules 150 (or, in some cases, mill line expansion modules 150 with a larger number of additional second presses 154a, 154b, although standard mill line expansion modules 150 may be preferred). The same apparatus 100 can meet the needs of both manufacturers, enabling efficient manufacturing and use of the apparatus 100 and the mill line expansion modules 150. Without modular design, it would be necessary to either i) market and produce various different sizes of equipment 100, or custom build equipment 100 for each manufacturer (both of which would involve inefficiencies and costs), or ii) produce only the largest possible equipment 100 with the maximum possible number of second presses 124a, 124b that could be used. In the latter case, equipment 100 could be prohibitively expensive, both in terms of purchase price and also in terms of maintenance of such a large piece of equipment 100 and the personnel required to supervise and operate it, for manufacturers who do not need to significantly reduce the thickness of the self-supporting electrode films 10a, 10b. Furthermore, because it lies in the path to the laminator 110, any unused second presses 124a, 124b in a given operation would increase the risk of damaging the self-supporting electrode films 10a, 10b, reducing the yield of operations, and a large number of unused second presses 124a, 124b would become a liability for the manufacturer.

[0031] A manufacturer producing various different products along the same line can be better serviced by the modular equipment 100, which allows the manufacturer to increase or decrease the number of presses by installing or removing mill line extension modules 150 as needed. The equipment 100 may be used with several mill line extension modules 150 for some operations and with fewer or no mill line extension modules 150 for other operations, thereby reducing the associated costs of these operations in terms of personnel and yield. Alternatively, a mill line extension module 150 may be used as a replacement in the event that presses 154a, 154b of another mill line extension module 150 require repair. Rather than shutting down the entire production line while waiting for the damaged press station to be repaired, the problematic mill line extension module 150 can simply be replaced with a new one. In this way, the manufacturing process can continue after only a temporary delay. Damaged mill line extension module 150 can be repaired without significantly disrupting production, even while the manufacturing process is in progress.

[0032] Figure 3 shows a workflow for manufacturing electrodes for an energy storage device using the disclosed innovation. In particular, the workflow in Figure 3 may be performed using the apparatus 100 described in relation to Figures 1 and 2. The workflow may begin with preparing first and second powder mixtures 12a and 12b (step 310) and fibrillating the binder contained in the powder mixtures 12a and 12b (step 320). For example, as described in the inventor's own patents and patent applications incorporated by reference above, the powder mixtures 12a, 12b may include, in addition to at least one type of electrode active material (e.g., lithium metal oxide in the case of the cathode, or graphite or silicon in the case of the anode), at least one type of fibrillable binder, for example, protetrafluoroethylene (polytetrafluoroethylene: PTFE), polyvinylpyrrolidone (polyvinylpyrrolidone: PVP), polyvinylidene fluoride (polyvinylidene fluoride: PVDF), polyethylene oxide (polyethylene: PEO), polyethylene (polyethylene: PE), or carboxymethylcellulose (carboxymethylcellulose: CMC), or a combination of the above binders or copolymers. The fibrillable binders may be characterized by their soft, flexible stiffness and, in particular, their extensibility, becoming longer and thinner and exhibiting a fibrous state when subjected to shear forces. By using one or more fibrillating binders that can be further chemically or thermally activated to enhance their flexibility, as described in the inventor's patents and patent applications, the powder mixture can be pressed into a self-supporting membrane without rupture and without the excessive use of toxic and expensive solvents such as N-methylpyrrolidone (NMP).The binder can be fibrillated by subjecting the powder mixtures 12a and 12b to shear force, for example, by using a kitchen blender, industrial blender, coffee grinder, grain mill grinder, high-speed mixer, cyclone paint mixer, rotary mixer, planetary mixer, high-shear disperser such as the Admix Rotosolver, high-shear granulator such as the Diosna P1-6, high-shear micronizer such as the Jet Mill, high-shear emulsifier, high-shear mixer such as the Ross Megashear mixer, or a soundproof mixer. As described above, in practice, the powder mixtures 12a and 12b may be divided from the same production batch. In this regard, it should be noted that steps 310 and 320 may be combined, or equivalently, step 310 may include preparing the first and second powder mixtures 12a and 12b without separating them (i.e., preparing enough powder mixture for two mill lines 120a and 120b).

[0033] The operation flow in Figure 4 may proceed to simultaneously produce first and second self-supporting electrode films 10a, 10b from powder mixtures 12a, 12b using a pair of mill lines 120a, 120b, such as those described in relation to Figures 1 and 2 (step 330). Figure 4 shows an exemplary sub-operation flow of this step, which may begin by inserting one or more mill line extension modules 150 into the mill lines 120a, 120b as needed to achieve specific specifications for each self-supporting electrode film 10a, 10b for the electrodes to be manufactured (e.g., thickness, density, and porosity, and mechanical strength such as tensile strength and elongation of the film) (step 410). With the mill lines 120a and 120b of the apparatus 100 appropriately expanded, the suboperation flow in Figure 4 may proceed to press the powder mixture 12a and 12b into their respective self-supporting electrode films 10a and 10b using their respective first presses 122a and 122b (step 420), support the self-supporting electrode films 10a and 10b as they pass through the mill lines 120a and 120b using the conveyors 126a and 126b (step 430), and reduce the thickness of their respective self-supporting electrode films 10a and 10b using any second presses 124a and 124b that are part of the base apparatus 100, and any additional second presses 154a and 154b added by the mill line expansion module 150 (step 440). The innovative design of the apparatus 100 allows the two self-supporting electrode films 10a and 10b to be simultaneously produced and properly thinned, thereby enabling subsequent feeding to the laminator 110 and simultaneous lamination onto the current collector 20.

[0034] In particular, referring again to Figure 3, the operation flow may proceed to feeding the first and second self-supporting electrode films 10a and 10b from their respective mill lines 120a and 120b to the laminator 110 (step 340). This may be done while continuing to support the self-supporting electrode films 10a and 10b on appropriately speed-controlled conveyors 126a and 126b, so that the possibility of breakage at the thinnest, lowest breaking strength, or most fragile locations of the films 10a and 10b is minimized. In this regard, the operation flow may further include measuring the tension of the self-supporting electrode films 10a, 10b at one or more locations using tension sensors 128a, 128b, 158a, 158b (step 350), and appropriately controlling the speed of the mill line as described above, in particular by adjusting the speed of the conveyors 126a, 126b, 156a, 156b (step 360) and / or the rotational speed of the work rolls. As the self-supporting electrode films 10a, 10b exit their respective mill lines 120a, 120b, the laminator 110 may laminate them on both sides of the current collector 20, which in some cases is pre-treated by chemical etching, coated with a conductive binder layer, or both (step 370). The completed electrodes may be wound onto a second spool 140 or cut by a cutting machine. By simultaneously producing self-supporting electrode films 10a, 10b using a pair of mill lines 120a, 120b and feeding the self-supporting electrode films 10a, 10b into a laminator 110 in a continuous process (particularly when the mill lines 120a, 120b are arranged as upstream wings of a separate central press functioning as the laminator 110), the disclosed manufacturing process can proceed at twice the speed of a process using the same single mill line to produce both films. In such a process, between film formation and lamination on the current collector, two rolls of the produced active material films and one roll of current collector must be loaded into a separate laminator machine, resulting in a final electrode lamination speed of up to half the speed of the mill line. The apparatus 100 of the disclosure is capable of twice the speed of such a multi-stage process.

[0035] Exemplary data for self-supporting electrode films 10a and 10b made from three different active materials are provided in Table 1 below.

[0036] Table 1 [Table 1]

[0037] To produce each group of films of a specified thickness ("Group of Films" column), the apparatus 100 of the disclosure may be equipped with a suitable number of presses ("Number of Presses" column). In this regard, the number of presses shown in Table 1 (ranging from 1 to 15 in this data) should be understood to refer to all presses in a given mill line 120a, including the first press 122a and the second press 124a, as well as any additional second presses 154a added using one or more mill line extension modules 150. For example, a 250 μm NCM cathode film group (number of presses = 1) can be produced using apparatus 100 which has a single first press 122a in the mill line 120a used to produce the film and does not have a second press 124a, while a 65 μm NCM cathode film group (number of presses = 15) can be produced using the same apparatus 100 which has a single first press 122a in the mill line 120a and 14 additional second presses 154a added by a mill line extension module 150. Table 1 shows the average thickness ("Average Thickness" column) illustrating the actual measured thicknesses corresponding to each film group in practice.

[0038] The last five columns of Table 1 show exemplary data for such membranes, where it can be seen that the tensile strength and density of the membrane are higher for thinner membranes and vary for different materials, while the elongation (maximum mechanical elongation before break) and porosity of the membrane are lower for thinner membranes and vary similarly for each material. The elongation can be determined by a tensile test (where mechanical direction may refer to the direction in which the membrane is stretched by the movement of the work rolls). An exemplary tensile test may measure the distance stretched before break of a strip of membrane 2.5 cm wide and 10 cm long (mechanical direction) at an initial tension of 5 gf, for example. It should be noted that NCM cathode and graphite anode membranes are more difficult to work with than activated carbon membranes, in particular, due to their significantly lower flexibility (and therefore lower elongation). As can be seen, this difficulty is even more apparent for thinner membranes. The apparatus 100 and associated processes described herein are intended to enable the successful and efficient production of a wide variety of self-supporting electrode films 10a, 10b in the same apparatus 100. For example, the self-supporting electrode films 10a, 10b may be made from various materials including NCM graphite or activated carbon, and may have thicknesses ranging from a maximum of 300 μm to a minimum of 50 μm or less. For each operation of apparatus 100, the mill lines 120a, 120b are appropriately configured for the desired thickness or other parameters and may be expanded as needed by inserting mill line expansion modules 150 to increase the number of thickness reduction presses. Furthermore, by an innovative design of the apparatus 100, which preferably includes conveyors 126a, 126b, 156a, 156b to support the fragile films 10a, 10b as they pass through the mill lines 120a, 120b before they are laminated onto the current collector 20, the resulting self-supporting electrode films 10a, 10b are intended to have tensile strengths ranging from 40 kPa to over 100 kPa, over 450 kPa, or even over 600 kPa (for NCM or graphite), or over 1100 kPa for very thin graphite anode films.Simultaneously, the elongation in the mechanical direction can range from 10% to as low as less than 4%, or even less than 2%, and sometimes as low as 0.50% or even 0.20% (in the case of NCM or graphite). Efficient handling of such fragile, self-supporting electrode films 10a, 10b would be impossible without the disclosed innovations of the apparatus 100 and associated processes.

[0039] Generally, self-supporting membranes having a tensile strength higher than 100 kPa and an elongation of less than 10% along the mechanical direction are intended to require a unique tension control design to enable a high-speed manufacturing process. The use of intended conveyors 126a, 126b, 156a, and 156b, combined with sensors 128a and 128b strategically placed along the self-supporting membrane (sometimes using multiple measurement methods), can provide the necessary control for handling the sensitive battery active material electrode membranes 10a and 10b. The difficulty in producing dry battery electrodes in self-supporting membranes stems from the inherently brittle nature of the active material, which makes conventional web handling methods impossible. By using conveyors 126a, 126b, 156a, and 156b to support the self-supporting electrode membranes 10a and 10b and transport them through an automated self-screw-in process through each press station, the apparatus 100 and methods of the disclosure can overcome these difficulties.

[0040] Advantageously, the multiple press designs of apparatus 100 can allow for greater flexibility in matching the final electrode properties, such as thickness uniformity, density, and porosity, compared to other dry process electrodes produced with or without self-supporting films. As shown in Table 1 above, for example, the film density may be selected as desired (e.g., between 3.02 g / cc and 3.40 g / cc for NCM cathodes, or between 1.21 g / cc and 1.71 g / cc for graphite anodes), and similarly, the film porosity may be selected as desired (e.g., between 25.9% and 34.2% for NCM cathodes, or between 23.5% and 46.0% for graphite anodes). Low porosity (e.g., less than 32%) is achievable through the efficient handling of brittle self-supporting electrode films 10a and 10b using apparatus 100. In general, dry battery electrode technology requires the ability to control the loading, porosity, and uniformity of the active material layer. Other dry battery electrode process technologies do not allow for precise control of these parameters. For example, dry spray or dry deposition electrode processes that do not produce self-supporting films may have limited ability to control thickness uniformity because the powder sits on top of the current collector and cannot flow along multiple axes during pressing. Also, density and porosity may be limited by the amount of powder that can be applied to the current collector before pressing and the limitations on the pressing force that can be used without damaging the current collector. The disclosed innovation can address all of these requirements by using multiple pressing stations that work together to simultaneously produce self-supporting electrode films 10a, 10b on both sides of the current collector 20. Furthermore, having thickness reduction pressing stations in the system in a modular configuration (with freely insertable mill line extension modules 150) rather than a fixed number of presses allows for customization based on different material types, such as anode material or custom cathode material.

[0041] Figure 5 shows the loading of the active material according to the film thickness of the activated dry NCM811 electrode (having a nickel:cobalt:manganese ratio of 8:1:1). As shown, the discharge capacity per unit area (mAh / cm²)2 The degree of loading of the active material, expressed as ), can be determined at least partially by the film thickness (μm). Electrodes made from thinner films (e.g., less than 90 μm) can have a capacitance of, for example, 6 mAh / cm². 2 Electrodes may exhibit a discharge capacity of less than 1 / cm² per unit area, which is typically suitable as a drop-in technique for high power density applications such as electric vehicles (EVs). On the other hand, electrodes made from thicker films (e.g., greater than 80 μm) may exhibit a discharge capacity of, for example, 6 mAh / cm². 2 It may exhibit a larger discharge capacity per unit area, which can typically be suitable for high-energy-density applications such as energy storage systems (ESS). Using conventional methods, such a wide range of applications would require different manufacturing equipment specialized for each application, which would result in significant costs and inefficiencies for manufacturers. In contrast, the embodiments of the apparatus 100 described herein advantageously allow a wide variety of electrodes to be produced using the same apparatus 100, and the thickness of the self-supporting films 10a, 10b and other parameters can be freely selected by modifying the number of thickness reduction presses 124a, 124b, 154a, 154b using the mill line extension module 150, thereby enabling the manufacture of batteries for, for example, EVs, ESSs, and other applications at relatively low cost and with high efficiency.

[0042] Figure 6 shows the C-rate performance of wet versus activated dry NCM811 electrodes (ADEs). Activated dry electrodes may refer to those produced by activated dry methods, such as those described herein and incorporated by reference, while intended wet electrodes (WET REFs) may be produced, for example, by conventional slurry coating methods. As can be seen, the performance of the electrodes at a given C-rate, expressed as discharge capacity retention (%), may depend on the thickness of the activated dry electrode film, with thinner ADE films (e.g., 54 μm) exhibiting better performance at higher C-rates than thicker ADE films (e.g., 78 μm) or wet electrodes. Therefore, manufacturers may desire to be able to freely adjust the electrode film thickness according to the desired C-rate of the battery being produced, but this is not easily done and is often not possible using conventional manufacturing equipment. However, with the embodiment of apparatus 100 described herein, the thickness of the self-supporting films 10a, 10b may be customizable as needed for the desired C-rate or other parameters of the energy storage device being produced.

[0043] In the example above, it was explained how the apparatus 100 could be used to produce a double-sided electrode by operating both mill lines 120a and 120b simultaneously and laminating two self-supporting electrode films 10a and 10b on both sides of the current collector 20. However, the processes described herein are not intended to be limited to using the apparatus 100 in this manner. For example, to produce a single-sided electrode, a single mill line 120a of the apparatus 100 may be operated, and the laminator 110 may laminate only a single self-supporting electrode film 10a onto the current collector 20. Furthermore, it should be understood that any of the work rolls 112-1, 112-2 of the laminator 110, work rolls 123a-1, 123a-2, 125a-1, 125a-2 of the mill line 120a, work rolls 155a-1, 155a-2 of the mill line extension module 150, and any corresponding work rolls provided in connection with the mill line 120b may be supported by one or more backing rolls, such as 4HI, 6HI, or cluster roll configurations.

[0044] The above description is provided as an example and is not limiting. Given the above disclosure, those skilled in the art can devise variations that fall within the spirit and scope of the invention disclosed herein. Furthermore, the various features of the embodiments disclosed herein can be used individually or in various combinations with each other and are not intended to be limited to the specific combinations described herein. Thus, the scope of the claims is not limited by the exemplary embodiments.

Claims

1. Apparatus for manufacturing electrodes for energy storage devices, wherein the apparatus: At least one laminator for simultaneously laminating two self-supporting electrode films on both sides of a current collector; and A pair of mill lines, each capable of generating the two self-supporting electrode films and simultaneously feeding the two self-supporting electrode films to the laminator, each of the mill lines is: A first press comprising at least one horizontally positioned work roll for pressing the powder mixture onto each of the self-supporting electrode films; and A second press including a work roll for reducing the thickness of each of the self-supporting electrode films. has A device equipped with the following features.

2. The apparatus according to claim 1, further comprising a mill line extension module, the mill line extension module being insertable into one of the pair of mill lines, and having at least one additional second press including a work roll for reducing the thickness of each of the self-supporting electrode films.

3. The apparatus according to claim 1, wherein each of the mill lines further comprises one or more conveyors arranged to support each of the self-supporting electrode films as they are fed from the at least one second press of the mill line to the laminator.

4. The apparatus according to claim 3, wherein the one or more conveyors are further arranged to support each of the self-supporting electrode films as it is fed from the first of the at least one second presses of the mill line to the second of the at least one second presses.

5. The apparatus according to claim 4, wherein the speed of the one or more conveyors between the at least one second press and the laminator of the mill line is controlled to be different from the speed of the one or more conveyors between the first of the at least one second press and the second of the at least one second press of the mill line.

6. The apparatus according to claim 4, wherein the one or more conveyors are further arranged to support each of the self-supporting electrode films as they are fed from the at least one first press to the at least one second press of the mill line.

7. The apparatus according to claim 3, wherein each of the mill lines further comprises one or more tension sensors arranged to measure the tension of the self-supporting electrode film, and the speed of the one or more conveyors of the mill line is controlled based on the measured tension.

8. The apparatus according to claim 7, wherein the tension measured by the one or more tension sensors of each mill line is further used to control the speed of the work roll of the at least one second press of the mill line.

9. The apparatus according to claim 3, wherein the one or more conveyors include at least one vacuum conveyor.

10. The apparatus according to claim 1, wherein the work rolls of at least one second press are arranged vertically.

11. A method for manufacturing electrodes for an energy storage device, wherein the method is: A step of providing the apparatus according to claim 1; A step of preparing a first powder mixture having an electrode active material and a fibrillable binder; A step of fibrillating the fibrillable binder in the first powder mixture by subjecting the first powder mixture to a shearing force; A step of pressing the first powder mixture onto a first self-supporting electrode film using at least one first press of the first mill line of the pair of mill lines; A step of reducing the thickness of the first self-supporting electrode film using the at least one second press of the first mill line; and The step of laminating the first self-supporting electrode film onto the first side of the current collector using at least one of the laminators. A method that includes [a certain feature].

12. A step of preparing a second powder mixture having an electrode active material and a fibrillable binder; A step of fibrillating the fibrillable binder in the second powder mixture by subjecting the second powder mixture to a shearing force; A step of pressing the second powder mixture onto a second self-supporting electrode film using at least one first press of the second mill line of the pair of mill lines; A step of reducing the thickness of the second self-supporting electrode film using the at least one second press of the second mill line; and Simultaneously with the lamination of the first self-supporting electrode film onto the first side of the current collector, the step of laminating the second self-supporting electrode film onto the second side of the current collector opposite the first side using at least one laminator. The method according to claim 11, further comprising:

13. A method for manufacturing electrodes for an energy storage device, wherein the method is: A step of preparing a first powder mixture having an electrode active material and a fibrillable binder; A step of fibrillating the fibrillable binder in the first powder mixture by subjecting the first powder mixture to a shearing force; A step of preparing a second powder mixture having an electrode active material and a fibrillable binder; A step of fibrillating the fibrillable binder in the second powder mixture by subjecting the second powder mixture to a shearing force; A step of simultaneously producing a first self-supporting electrode film from the first powder mixture and a second self-supporting electrode film from the second powder mixture using a pair of mill lines, each of the mill lines having at least one first press including a horizontally positioned work roll for pressing the respective powder mixtures into the respective self-supporting electrode films, and at least one second press including a work roll for reducing the thickness of the respective self-supporting electrode films; and Following the step of generating the first self-supporting electrode film and the second self-supporting electrode film, the first self-supporting electrode film and the second self-supporting electrode film are fed from their respective mill lines to a laminator, and the first self-supporting electrode film and the second self-supporting electrode film are laminated on both sides of the current collector. A method that includes [a certain feature].

14. The method according to claim 13, further comprising the step of supporting the first self-supporting electrode film using one or more conveyors when the first self-supporting electrode film is fed from each of the mill lines to the laminator.

15. The method according to claim 14, further comprising the step of supporting the first self-supporting electrode film using the one or more conveyors when the first self-supporting electrode film is fed from the first of the at least one second presses of each mill line to the second of the at least one second presses.

16. The method according to claim 15, further comprising the step of controlling the speed of the one or more conveyors between each mill line and the laminator so as to be different from the speed of the one or more conveyors between the first of the at least one first presses and the second of the at least one first presses of each mill line.

17. The method according to claim 15, further comprising the step of supporting the first self-supporting electrode film using one or more conveyors when the first self-supporting electrode film is fed from the at least one first press to the at least one second press on each of the mill lines.

18. The method according to claim 14, further comprising the steps of measuring the tension of the first self-supporting electrode film and controlling the speed of the one or more conveyors based on the measured tension.

19. The method according to claim 18, further comprising the step of controlling the speed of the work roll of the at least one second press based on the measured tension.

20. The method according to claim 14, wherein the one or more conveyors include at least one vacuum conveyor.

21. The method according to claim 13, wherein the work rolls of at least one second press are arranged vertically.

22. A self-supporting electrode film, Electrode active material; and Fibrillable binder A self-supporting electrode film comprising the above, wherein the mechanical elongation rate of the self-supporting electrode film is less than 2%.

23. The self-supporting electrode film according to claim 22, wherein the tensile strength of the self-supporting electrode film in the mechanical direction is greater than 100 kPa.

24. The self-supporting electrode film according to claim 22, wherein the porosity of the self-supporting electrode film is less than 32%.

25. A self-supporting electrode film, Electrode active material; and Fibrillable binder A self-supporting electrode film comprising the above, wherein the porosity of the self-supporting electrode film is less than 32%.

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