Method for dry coating of electrodes using a perforated current collector with non-perpendicular hole orientation

Abstract

The present invention discloses a method for manufacturing an electrode for an energy storage device. The method comprises applying an electrode composition to a perforated current collector using a dry coating process, wherein inner wall surfaces of the collector's holes are oriented at a non-right angle relative to a longitudinal plane of the collector. This non-right angle orientation can be achieved, for example, by providing the current collector with a non-planar surface, and / or by providing holes wherein a mean hole opening area on a first surface differs from a mean hole opening area on a second surface. This angled configuration enhances the mechanical anchoring and packing density of the electrode composition within the holes. An electrode and a current collector are also provided.

Description

[0001] METHOD FOR DRY COATING OF ELECTRODES USING A PERFORATED CURRENT COLLECTOR WITH NON-PERPENDICULAR HOLE ORIENTATION

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to methods for manufacturing electrodes using a dry coating process, and more particularly to such methods employing perforated current collectors with specific structural features for use in energy storage and / or generation devices, such as lithium-ion batteries.

[0004] BACKGROUND OF THE INVENTION

[0005] Lithium-ion batteries are widely used in various applications, including consumer electronics, electric vehicles, and energy storage systems. The performance and reliability of these batteries significantly depend on the quality of the electrodes, which are typically composed of active materials coated onto current collectors. Traditional methods for applying these coatings often involve wet processes that require solvents and additional drying steps. Dry coating processes, which eliminate the need for solvents, offer advantages in terms of environmental impact, cost, and manufacturing efficiency. However, dry coating processes face challenges in achieving uniform coatings and adhesion sufficient to provide the required cycle life.

[0006] Currently available solutions that are configured to improve electrode adhesion and uniformity involve pre-treatment of a current collector. In this process, the current collector, typically in the form of a metal foil such as aluminum or copper foil, is coated with a thin layer of primer material that serves as an adhesion promoter. This primer layer can be composed of materials like conductive polymers, carbon-based substances, and / or binders, which provide a better surface for the subsequent application of dry electrode powders. While the use of primed electrodes may address the challenge of poor adhesion and facilitate a more uniform distribution of the active materials across the electrode surface, current collector priming adds complexity and cost to the manufacturing process and creates potential issues with primer material compatibility and long-term stability.Therefore, there is a need for improved electrodes that are stable for the long term, and for methods for producing the same though dry-coating of current collectors, wherein the coating is cost-effective and not complex, while maintaining a long term stable adhesion to the current collector.

[0007] SUMMARY OF THE INVENTION

[0008] The present invention addresses the challenges associated with dry coating processes for manufacturing electrodes, particularly the difficulty in achieving sufficient adhesion of the electrode material on a perforated current collector. The invention provides a method that, according to some embodiments, utilizes a specifically configured perforated current collector to enhance the mechanical integrity of the final electrode. The core of the method, according to some embodiments, involves creating a non-perpendicular interface between the inner walls of the collector's perforations and the applied electrode composition. This is achieved, according to some embodiments, by providing a perforated current collector where the inner wall surfaces of the holes are oriented at a non-right angle relative to the longitudinal plane of the collector. Without wishing to be bound by any theory or mechanism of action, when an electrode composition, such as a dry film, is applied parallel to this plane, the angled interaction promotes a more effective mechanical interlocking and denser packing of the material within the holes. Advantageously, this improves adhesion, stability, and the overall performance and reliability of the resulting electrode.

[0009] Thus, according to some embodiments, there is provided a method for manufacturing an electrode, which comprises providing a perforated current collector that includes a plurality of holes, a first surface, and an opposite second surface. According to some embodiments, the perforated current collector is configured such that inner wall surfaces of at least a portion of the plurality of holes are oriented at a non-right angle relative to a longitudinal plane of the current collector. The method further comprises, according to some embodiments, applying a first electrode composition to at least a first section of the first surface using a dry coating process while the first electrode composition is disposed generally parallel to the longitudinal plane. According to some embodiments, the method comprises bringing the first electrode composition into contact with the inner wall surfaces at the non-right angle. Advantageously, this specific angled contact enhances the mechanical anchoring of theelectrode material within the perforations, leading to improved adhesion and structural integrity of the final electrode.

[0010] As detailed herein, according to some embodiments, the method of the present invention relies on a specific geometric relationship between the applied electrode composition and the inner walls of the perforations in the current collector. The longitudinal plane of the current collector, as defined herein, may serve as a primary reference plane, representing the general plane of the foil as it moves through the manufacturing process. The electrode composition is typically provided as a dry, self-supporting sheet or film. In this context, the phrase "disposed generally parallel" means that the major surface of this electrode film is aligned with the longitudinal plane of the current collector as they are brought into contact. This alignment is characteristic of roll-to-roll lamination processes, where both the collector foil and the electrode film are fed into a pair of rollers in parallel planes.

[0011] Without wishing to be bound by any theory or mechanism of action, this parallel application is critical to realizing the benefits of the invention. In perforated collectors where the hole walls are perpendicular to the surface, a parallel-applied film would contact the hole walls at a right angle (90°). In contrast, the present invention utilizes a current collector where at least a portion of the plurality of holes have inner hole walls which are intentionally configured to be at a non-right angle to the longitudinal plane. Consequently, when the electrode film is applied parallel to this plane, it engages the slanted inner walls of the holes at an oblique, non-right angle. This angled interaction creates a more complex interface, which extends the path of the electrode material into the perforation and provides a stronger mechanical anchor compared to a simple perpendicular interface.

[0012] The phrase "at least a portion of the plurality of holes" indicates that a significant number, but not necessarily all, of the perforations in the current collector are configured with the specified non-right- angle orientation. The portion of the plurality of holes having an inner wall surface that forms a non-right angle with the longitudinal plane of the current collector may range from about 20% to about 100%, including each value and sub-range within the specified range. According to some embodiments, at least 20% of the plurality of holes are oriented at a non-right angle relative to a longitudinal plane of the current collector. According to some embodiments, at least 40% of the plurality of holes are oriented at a non-right angle relative to a longitudinalplane of the current collector. According to some embodiments, at least 50% of the plurality of holes are oriented at a non-right angle relative to a longitudinal plane of the current collector. According to some embodiments, at least 75% of the plurality of holes are oriented at a non-right angle relative to a longitudinal plane of the current collector. According to some embodiments, at least 90% of the plurality of holes are oriented at a non-right angle relative to a longitudinal plane of the current collector. According to some embodiments, essentially every hole of the current collector has an inner wall surface that forms a non-right angle with the longitudinal plane of the current collector, ensuring a consistent and uniform anchoring effect across the entire surface. According to some embodiments, the phrase "essentially every hole" refers to a condition where a substantial majority of the holes of the perforated current collector meet the specified criteria. The phrase refers to a configuration wherein both the total number, the locations and the spatial distribution of any holes that do not exhibit the non-right- angle orientation are such that their cumulative presence does not materially affect the characteristic performance of the resulting electrode, such as its overall material adhesion and packing density, when compared to an electrode prepared with a current collector in which all of the holes have the non-right- angle orientation.

[0013] The present methods may be particularly advantageous for dry coating processes, which are essentially solvent-free, typically containing less than 10 wt% of any solvent. The first electrode composition may be formed into a film by processing a dry mixture of components, which generally includes an electrode active material and a binder, such as polytetrafluoroethylene (PTFE). The binder may be fibrillated to provide the structural integrity for the film. By improving the physical anchoring of this dry film to the current collector, the method reduces the risk of delamination and enhances the overall durability and electrical performance of the resulting electrode without the need for adhesion-promoting primer layers.

[0014] According to some embodiments, the required non-right- angle orientation between the inner hole walls and the longitudinal plane is achieved by providing the perforated current collector with a non-planar surface. According to some embodiments, by distributing the plurality of through-holes over this non-planar surface, the inner wall surfaces of holes located on the sloped regions are inherently tilted. This configuration may ensure that when the electrode composition is appliedgenerally parallel to the longitudinal plane, it contacts these inner wall surfaces at the desired non-right angle, according to some embodiments.

[0015] Without wishing to being bound by theory or mechanism of action, it is contemplated that while the perforated structure of the current collector enables the mechanical interlocking of the dry-coated materials through the holes of the current collector, said non-right angle formed between the electrode composition and the inner surface of the hole wall may enable a more efficient spreading of the solventless electrode active material within the holes. This unique combination of features can enable the formation of a more compact electrode structure, further enhancing the adhesion, integrity and stability, as well as improving electrical conductivity of the dry-coated electrode formed by such process. The improved adhesion and electric conductivity may, in turn, improve the overall performance, reliability and cycle-life of lithium-ion batteries that include electrodes (e.g. cathodes) that are formed by the present method.

[0016] Moreover, this tilted configuration may provide an anchoring effect for the electrode composition, especially beneficial in single-sided coating processes. When the electrode composition meets the hole walls at a non-right angle, even if the coating is applied only to one side of the current collector, the angled interaction between the electrode composition and the hole walls may create a mechanical anchoring within the perforations by densely filling the entire hole volume and creating a close contact with the entire surface of the hole wall. This anchoring effect may improve the adhesion of the electrode composition to the current collector, reducing the likelihood of delamination and enhancing the structural integrity of the electrode layer of a singlesided electrode. Thus, a resulting electrode that includes a single-sided coated current collector will advantageously have better long-term stability.

[0017] Atypical roll-to-roll dry coating process involves a lamination step that includes applying a solid film containing an electrode active material, and, optionally a binder and a conductive additive to a current collector. The application of the electrode active material can be performed by passing the current collector and the film between a pair of rollers, wherein the foil is being positioned in parallel to the current collector at the contact region between the rollers. In order to create a non-right angle between the electrode composition and the hole walls of the perforated current collector when the electrode composition contacts the current collector, the current collector may have anon-flat surface in a longitudinal plane thereof. As current collectors are typically in the shape of an elongated sheet or foil that has two perpendicular planes, the “longitudinal plane” typically refers to the longer of the two planes the “lateral plane” typically refers to the shorter of the two planes. Similarly, the term “longitudinal direction” is used herein to refer to the direction of elongation of the current collector, and the term “longitudinal axis” is used herein to refer to an axis, which extends along the longitudinal direction, the term “lateral direction” is used herein to refer to the direction perpendicular to the direction of elongation of the current collector, and the term “lateral axis” is used herein to refer to an axis, which extends along the lateral direction.

[0018] Such perforated current collector having a non-flat or non-planar surface (also termed herein “three-dimensional perforated current collector" or “3D perforated current collector”) may, for example, include periodically alternating round bulges and depressions. In a conventional (flat) perforated current collector, an intercept angle formed by the surface of the current collector foil and the inner wall surface of a straight penetrating hole is about 90 degrees. In a 3D perforated current collector, the penetrating holes are distributed along curved lines or surfaces. The longitudinal axis of a plurality of said holes is not parallel to the longitudinal plane of the current collector. The walls of such holes form a non-right angle with respect to the longitudinal plane of the current collector, and when the electrode composition is applied in a form of the film during the lamination step it is likewise in a non-right orientation with the hole walls.

[0019] While at the beginning of the dry-coating process the current collector surface is non-planar, it should be emphasized that the three-dimensional structure does not need to be maintained throughout the entire dry coating process. Thus, the resulting electrode may include a current collector that is essentially flat, e.g., it may be flattened during the coating. Without wishing to being bound by theory or mechanism of action, it is contemplated that the flattening of the 3D perforated current collector during the lamination process may further enhance the active material packing within the holes and improve adhesion, as well as increase the uniformity of the active material distribution along the longitudinal plane of the current collector.

[0020] Thus, according to some embodiments, the first section of the first surface is non-planar. According to some embodiments, there is provided a method for manufacturing an electrode, comprising applying a first electrode composition to atleast a first section of a first surface of a perforated current collector comprising a plurality of holes, using a dry coating process, wherein at least a portion of the plurality of holes have an inner wall surface that forms a non-right angle with a longitudinal plane of the current collector.

[0021] According to some embodiments, the present invention provides a method for manufacturing an electrode, comprising applying a first electrode composition to at least a first section of a first surface of a perforated current collector comprising a plurality of holes, wherein at least a portion of the plurality of holes have an inner wall surface that forms a non-right angle with a longitudinal plane of the current collector, and wherein the first electrode composition contains less than about 10% wt. of a solvent, based on the total weight of the first electrode composition.

[0022] According to some embodiments, the present invention provides a method for manufacturing an electrode, comprising applying a first electrode composition to at least a first section of a first surface of a perforated current collector comprising a plurality of holes using a dry coating process, wherein the first section of the first surface is non-planar.

[0023] According to some embodiments, there is provided a method for manufacturing an electrode, comprising applying a first electrode composition to at least a first section of a first surface of a perforated current collector comprising a plurality of holes, wherein the first section of the first surface is non-planar, and wherein the first electrode composition contains less than about 10% wt. of a solvent, based on the total weight of the first electrode composition.

[0024] According to some embodiments, the electrode is for an energy storage and / or generation device. Each possibility represents a separate embodiment of the invention. According to some embodiments, the electrode is for a battery. According to some embodiments, the electrode is for a lithium-ion battery.

[0025] It is to be understood that sheet-shaped materials, such as foils, have two surfaces. The term “section” of a surface is used herein to define any area within a surface, including the entire surface.

[0026] According to some embodiments, the first section of the first surface is perforated. According to some embodiments, the first surface is perforated.According to some embodiments, the first section of the first surface is non-planar. According to some embodiments, the first surface is non-planar.

[0027] In contrast to a “planar” element, such a simple planar sheet or foil, the surface of which has a topography which is extended only in two dimensions of space, the term “non-planar” structure denotes a three-dimensional structure having a surface which has an extent in all three dimensions of space.

[0028] According to some embodiments, the method further comprises transforming a substantially flat current collector into a non-planar current collector, which comprises the non-planar surface.

[0029] The non-planar surface may include elements selected from the group consisting of peaks, protrusions, ridges, bulges, bumps, creases, valleys, and depressions. Each possibility represents a separate embodiment of the invention. The non-planar first section may include elements selected from the group consisting of peaks, protrusions, ridges, bulges, bumps, creases, valleys, and depressions. Each possibility represents a separate embodiment of the invention. The elements may be aligned in straight lines. In some embodiments, the elements are aligned in tilted lines, which are tilted with respect to a longitudinal axis of the perforated current collector. According to some embodiments, the elements are embossed elements.

[0030] In certain embodiments, the embossed elements comprise periodically alternating round bulges and depressions. The bulges and depressions may be arranged in a seamless repeating embossing pattern.

[0031] In this context, the term "round" means that the bulges and depressions have no corners at least in cross-section. The round shape can be oval or circular.

[0032] A horizontal distance between centers of two adjacent bulges or depressions may range from about 100 pm to about 1000 pm, including each value and sub-range within the specified range. A vertical distance between the highest point of a bulge and the lowest point of a depression adjacent thereto may range from about 20 pm to about 100 pm, including each value and sub-range within the specified range. In some embodiments, said vertical distance is about 3 to 8 times higher than a local thickness of the perforated current collector, including each value and sub-range within the specified range. In additional embodiments said vertical distance is reduced by at least about 80% following application of the first electrode composition. According to someembodiments, applying the first electrode composition to the first section of a first surface entails reducing the vertical distance by at least about 80%.

[0033] In some embodiments, the perforated current collector has a local thickness ranging from about 4 pm to about 30 pm, including each value and sub-range within the specified range. In some embodiments, the perforated current collector has a local thickness ranging from about 5 pm to about 20 pm.

[0034] The plurality of holes of the perforated current collector may be arranged in a seamless repeating perforation pattern. In some embodiments, the seamless repeating perforation pattern spans over at least 90% of the first surface of the perforated current collector. According to some embodiments, the seamless repeating perforation pattern spans over at least 90% of the first section of the perforated current collector.

[0035] According to some embodiments, the first section spans over at least 70% of the first surface. According to some embodiments, the first section spans over at least 80% of the first surface. According to some embodiments, the first section spans over at least 90% of the first surface. According to some embodiments, the first section spans over at least 95% of the first surface.

[0036] According to some embodiments, the method comprises applying the first electrode composition to at least the first surface of the perforated current collector. According to some embodiments, the method comprises applying the first electrode composition to the entire first surface of the perforated current collector.

[0037] In some embodiments, the plurality of holes have a mean opening size ranging from about 50 pm to about 500 pm, including each value and sub-range within the specified range. In further embodiments, the mean opening size ranges from about 80 pm to about 200 pm. In certain embodiments, the mean opening size is about 150 pm.

[0038] In some embodiments, a hole pitch ranges from about 100 pm to about 1000 pm, including each value and sub-range within the specified range. In further embodiments, the hole pitch ranges from about 250 pm to about 650 pm. In further embodiments, the hole pitch ranges from about 250 pm to about 350 pm. In additional embodiments, the hole pitch ranges from about 300 pm to about 400 pm. In some embodiments, the hole pitch ranges from about 600 pm to about 700 pm.In some embodiments, an open area of the perforated current collector ranges from about 1% to about 40%, including each value and sub-range within the specified range. In further embodiments, the open area ranges from about 3% to about 7%. In certain embodiments, the open area ranges from about 10% to about 20%. In additional embodiments, the open area ranges from about 20% to about 30%.

[0039] In some embodiments, an open area of the first section ranges from about 1% to about 40%, including each value and sub-range within the specified range. In further embodiments, the open area ranges from about 3% to about 7%. In certain embodiments, the open area ranges from about 10% to about 20%. In additional embodiments, the open area ranges from about 20% to about 30%.

[0040] In some embodiments, an open area of the first surface ranges from about 1% to about 40%, including each value and sub-range within the specified range. In further embodiments, the open area ranges from about 3% to about 7%. In certain embodiments, the open area ranges from about 10% to about 20%. In additional embodiments, the open area ranges from about 20% to about 30%.

[0041] The plurality of holes of the perforated current collector may have a shape selected from the group consisting of a circular, essentially circular, elliptical, oval, polygonal, rounded polygonal, irregular shape, and any combination thereof. Each possibility represents a separate embodiment of the invention.

[0042] The perforated current collector may include a metal selected from the group consisting of aluminum, copper, nickel, stainless steel, silver, zinc, tin, iron, titanium, and any combination or alloy thereof. In certain embodiments, the metal is aluminum. Each possibility represents a separate embodiment of the invention.

[0043] Application of the electrode composition may be performed in a roll-to-roll system. The application of the electrode composition may include laminating the first electrode composition and the perforated current collector between a pair of rollers, wherein the first surface of the current collector faces the first electrode composition. In some embodiments, the current collector has a second surface opposite the first surface, wherein the second surface is non-planar. The method may further include applying a second electrode composition to a second section of the second surface of the perforated current collector.In some embodiments, the dry coating process includes simultaneously laminating the first electrode composition, the second electrode composition, and the perforated current collector between the pair of rollers, wherein the first surface of the current collector faces said first electrode composition, and the second surface of the current collector faces said second electrode composition. Lamination may be performed by applying a press force of about 20 kN to about 200 kN. In some embodiments, the lamination is performed by applying a press force of about 60-150 kN. Thus, according to some embodiments, the lamination comprises applying pressure so that the first electrode composition and current collector are pressed one against the other. According to some embodiments, upon the application of pressure the first section of the first surface becomes at least partially flattened. According to further embodiments, upon the application of pressure the second section of the second surface becomes at least partially flattened.

[0044] It is to be understood that the terms “flattening” and “flattened” are relative and relate to the state of an object after an action has been taken. Specifically, the phrase “upon the application of pressure the first section of the first surface becomes at least partially flattened” should be interpreted as the first surface and / or the second surface is more flat after the application of pressure than it was before the application of pressure.

[0045] According to some embodiments, the lamination entails forming a substantially flat laminated current collector.

[0046] It is to be understood that the term “substantially flat” includes a portion that may not be perfectly flat. Substantially flat surfaces are generally defined as a having a low ratio between the total thickness and the local thickness thereof, for example, a ratio of no more than 1.1 to 1.

[0047] According to some embodiments, upon the application of pressure the vertical distance is reduced by at least about 80% following application of the first electrode composition

[0048] The first electrode composition may be present in a form of a film. In some embodiments, the first electrode composition contains less than about 10 wt% of the solvent, based on the total weight of the first electrode composition. In certainembodiments, the first electrode composition contains less than about 1 wt% of the solvent.

[0049] The term “solvent” has used herein refers to any material, which is liquid at room temperature and is capable of at least partially dissolving or dispersing solid components of the electrode composition. The term is not limited to a single liquid and may include a mixture.

[0050] The first electrode composition may include an electrode active material selected from the group consisting of lithium nickel manganese cobalt oxide (NMC), lithium iron phosphate (LFP), lithium iron manganese phosphate, lithium nickel manganese oxide, lithium cobalt oxide, lithium nickel cobalt aluminum oxide, lithium cobalt aluminum oxide, lithium titanium oxide, sulfur, lithium sulfide, graphite, silicon oxide, and any combination thereof . In some embodiments, lithium nickel manganese cobalt oxide has a nickel content of at least about 80 at% based on the total weight of nickel manganese cobalt.

[0051] The electrode active material may be present in the first electrode composition in a weight percent ranging from about 90 wt% to about 100 wt%, based of the total weight of the first electrode composition.

[0052] In some embodiments, the first electrode composition comprises a binder. The binder may be selected from the group consisting of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), cellulose and any combination and derivative thereof. The binder may be present in the first electrode composition in a weight percent of 2 wt% or less, based on the total weight of the first electrode composition. The binder may be present in the first electrode composition in a fibrilized form. In some embodiments, the binder comprises particles having a mean particle size below about 20 pm.

[0053] The first electrode composition may be obtained by dry mixing components of the first electrode composition and subjecting an obtained dry mixture to a fibrilization process, which is optionally followed by grinding and / or sieving.

[0054] A thickness of the first electrode composition applied to at least the first section of the first surface of the perforated current collector may range from about 5 pm to about 250 pm, including each value and sub-range within the specified range.According to some embodiments, the method comprises applying a second electrode composition to at least a second section of a second surface of the perforated current collector. According to some embodiments, the second surface is in an opposite side to the first surface of the current collector.

[0055] According to some embodiments, the second section of the second surface is perforated. According to some embodiments, the second surface is perforated.

[0056] According to some embodiments, the second section of the second surface is non-planar. According to some embodiments, the second surface is non-planar. Non-planar features may include embossed elements as defined herein for the first surface and first section thereof and properties (e.g., horizontal / vertical distances, local thickness) as also defined herein for the first surface and first section thereof.

[0057] According to some embodiments, the method comprises applying the second electrode composition to the second surface of the perforated current collector. According to some embodiments, the method comprises applying the second electrode composition to essentially the entire second surface of the perforated current collector.

[0058] According to some embodiments, the second section spans over at least 70% of the second surface. According to some embodiments, the second section spans over at least 80% of the second surface. According to some embodiments, the second section spans over at least 90% of the second surface. According to some embodiments, the second section spans over at least 95% of the second surface.

[0059] According to some embodiments, the second electrode composition is essentially the same as the first electrode composition.

[0060] The term “essentially the same composition” as used herein is intended to mean a composition containing at least 80%, at least 90%, at least 95% or at least 99% by weight of the same components, and with amounts of the same components in a composition containing at most 20 % compositional variance, relative to a composition with which it is compared, said percentages by weight being determined relative to the total weight of a composition.

[0061] According to some embodiments, the second electrode composition contains less than about 10 wt% of the solvent, based on the total weight of the second electrodecomposition. In certain embodiments, the second electrode composition contains less than about 1 wt% of the solvent.

[0062] The second electrode composition may include an electrode active material selected from the group consisting of lithium nickel manganese cobalt oxide (NMC), lithium iron phosphate (LFP), lithium iron manganese phosphate, lithium nickel manganese oxide, lithium cobalt oxide, lithium nickel cobalt aluminum oxide, lithium cobalt aluminum oxide, lithium titanium oxide, sulfur, lithium sulfide, graphite, silicon oxide, and any combination thereof. In some embodiments, lithium nickel manganese cobalt oxide has a nickel content of at least about 80 at% based on the total weight of nickel manganese cobalt.

[0063] The electrode active material may be present in the second electrode composition in a weight percent ranging from about 90 wt% to about 100 wt%, based of the total weight of the second electrode composition.

[0064] In some embodiments, the second electrode composition comprises a binder. The binder may be selected from the group consisting of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), cellulose and any combination and derivative thereof. The binder may be present in the second electrode composition in a weight percent of 2 wt% or less, based on the total weight of the second electrode composition. The binder may be present in the second electrode composition in a fibrilized form. In some embodiments, the binder comprises particles having a mean particle size below about 20 pm.

[0065] The second electrode composition may be obtained by dry mixing components of the second electrode composition and subjecting an obtained dry mixture to a fibrilization process, which is optionally followed by grinding and / or sieving.

[0066] A thickness of the second electrode composition applied to the second section of the second surface of the perforated current collector may range from about 5 pm to about 250 pm, including each value and sub-range within the specified range.

[0067] According to some embodiments, the second electrode composition is the same as the first electrode composition.According to some embodiments, the second electrode composition is provided in the form of a film. According to some embodiments, each one of the first electrode composition and the second electrode composition is provided in the form of a film.

[0068] According to some embodiments, the application of the second composition to the second section is performed in a roll-to-roll system. According to some embodiments, the application comprises laminating the perforated current collector and second electrode composition between a pair of rollers. According to some embodiments, the application of both electrode compositions is performed together in a roll-to-roll system, and comprises laminating the perforated current collector and electrode compositions between a pair of rollers. According to some embodiments, upon the simultaneous lamination the perforated current collector is positioned between the electrode composition films.

[0069] According to some embodiments, the lamination comprises applying pressure so that current collector is pressed between the first and second electrode compositions. According to some embodiments, upon the application of pressure, the second section of the second surface becomes at least partially flattened. According to some embodiments, upon the application of pressure, each one of the first section of the first surface and the second section of the second surface becomes at least partially flattened.

[0070] According to some embodiments, applying the second electrode composition to the second section of the second surface entails reducing the vertical distance between the highest point of a bulge and the lowest point of a depression adjacent thereto by at least about 80%.

[0071] According to some embodiments, upon application of both the first electrode composition and the second electrode composition to the perforated current collector, at least 80% of the total surface of the perforated current collector becomes covered by the electrode compositions. According to some embodiments, upon application of both the first electrode composition and the second electrode composition to the perforated current collector, at least 90% of the total surface of the perforated current collector becomes covered by the electrode compositions. According to some embodiments, upon application of both the first electrode composition and the second electrode composition to the perforated current collector, at least 95% of the total surface of the perforated current collector becomes covered by the electrode compositions. Accordingto some embodiments, upon application of both the first electrode composition and the second electrode composition to the perforated current collector, at least 97% of the total surface of the perforated current collector becomes covered by the electrode compositions.

[0072] According to some embodiments, upon application of both the first electrode composition and the second electrode composition to the perforated current collector the first electrode composition contacts the second electrode composition through at least some of the plurality of holes. According to some embodiments, upon application of both the first electrode composition and the second electrode composition to the perforated current collector the first electrode composition contacts the second electrode composition through at least 80% of the plurality of holes. According to some embodiments, upon application of both the first electrode composition and the second electrode composition to the perforated current collector the first electrode composition contacts the second electrode composition through at least 90% of the plurality of holes. According to some embodiments, upon application of both the first electrode composition and the second electrode composition to the perforated current collector the first electrode composition contacts the second electrode composition through at least 95% of the plurality of holes.

[0073] According to some embodiments, upon application of the first electrode composition or both the first electrode composition and the second electrode composition to the perforated current collector the first electrode composition and the second electrode composition occupy at least 50% of a total volume of the plurality of holes. According to some embodiments, upon application of the first electrode composition or both the first electrode composition and the second electrode composition to the perforated current collector the first electrode composition and the second electrode composition occupy at least 80% of a total volume of the plurality of holes. According to some embodiments, upon application of the first electrode composition or both the first electrode composition and the second electrode composition to the perforated current collector the first electrode composition and the second electrode composition occupy at least 90% of a total volume of the plurality of holes. According to some embodiments, upon application of the first electrode composition or both the first electrode composition and the second electrode composition to the perforated current collector the first electrode composition and thesecond electrode composition occupy at least 95% of a total volume of the plurality of holes.

[0074] According to some embodiments, the method further comprises cutting the dry-coated current collector to form a plurality of electrodes.

[0075] Further provided is an electrode prepared by the method disclosed in the aspect and embodiments hereinabove.

[0076] In some embodiments, at least about 90% of a total volume of the plurality of holes of the perforated current collector in said electrode is filled by the electrode composition. It is to be understood that the phrase “filled by the electrode composition” in the present context is intended to mean that either the first electrode composition or the first electrode composition and second electrode composition combined, depending on the embodiment, is occupying 90% or more of the hole volume.

[0077] In some embodiments, the first electrode composition is in a direct contact with at least the first surface of the perforated current collector. In further embodiments, the first surface of the perforated current collector is in a direct contact with the first electrode composition and the second surface of the perforated current collector is in a direct contact with the second electrode composition. Preferably, the first electrode composition and the second electrode composition are combined through the plurality of holes of the perforated current collector.

[0078] The volumetric density of the first electrode composition on the first surface and / or the volumetric density of the second electrode composition on the second surface may be at least about 3.1 g / cm3. In some embodiments, the volumetric density of the first electrode composition on the first surface and / or the volumetric density of the second electrode composition on the second surface is at least about 3.3 g / cm3. In certain embodiments, the volumetric density of the first electrode composition on the first surface and / or the volumetric density of the second electrode composition on the second surface is at least about 3.5 g / cm3.

[0079] The volumetric density of the first electrode composition on the first section and / or the volumetric density of the second electrode composition on the second section may be at least about 3.1 g / cm3. In some embodiments, the volumetric density of the first electrode composition on the first section and / or the volumetric density of the second electrode composition on the second section is at least about 3.3 g / cm3. Incertain embodiments, the volumetric density of the first electrode composition on the first section and / or the volumetric density of the second electrode composition on the second section is at least about 3.5 g / cm3.

[0080] According to some embodiments, the electrode formed by the present method is substantially flat.

[0081] According to some embodiments, the method achieves the required non-right-angle orientation through the specific geometry of the holes themselves. In this configuration, the method utilizes a perforated current collector with holes which have an opening size on one surface of the current collector that is different from the hole opening size on the opposite surface thereof. This unique tapered geometry, which results in slanted inner walls, enables enhanced penetration of the electrode composition into the perforations.

[0082] Advantageously this can lead to improved packing density, mechanical anchoring, and overall electrode performance. Without wishing to being bound by theory or mechanism of action, it is contemplated that the holes that have larger openings on one side of the current collector provide a funnelling effect for better electrode materials distribution and compaction. It has been surprisingly found by the inventors of the present invention that said specific design of the holes provides an improved anchoring effect for the electrode composition even in single-sided coating processes (i.e., upon application of electrode composition to one of the surface). Advantageously the method, in either double side-coated or single-sided coating variations thereof, results in densely filling the hole volume and creating a close contact with substantially the entire surface of the hole wall. Thus, a resulting electrode that includes either a single- sided coated current collector or double side-coated current collector will advantageously have better long-term stability.

[0083] Atypical roll-to-roll dry coating process involves a lamination step that includes applying a dry film containing an electrode active material, and, optionally a binder and a conductive additive to a current collector. The application of the electrode active material can be performed by passing the current collector and the film between a pair of rollers, wherein the foil is being positioned in parallel to the current collector at the contact region between the rolls. The inventors have further discovered that the use of the perforated current collectors having different opening sizes on the opposite sides ofthe current collector in a roll-to-roll dry coating process may result in uneven electrode composition thickness on the opposite sides on the current collector, possibly due to the higher penetration of the dry film that has a fixed thickness into the wider opened holes. Said imbalance, however, may be mitigated by the perforated structure of the current collector, e.g., by providing improved ionic pathways.

[0084] Thus, according to some embodiments, a mean hole opening area of the plurality of holes on the first surface differs from a mean hole opening area of the plurality of holes on a second surface of the perforated current collector, wherein the second surface is in an opposite side to the first surface of the current collector. According to some embodiments, the mean hole opening area of the plurality of holes on the first surface differs from a mean hole opening area of the plurality of holes on a second surface of the perforated current collector, by at least about 20%.

[0085] According to some embodiments, the present invention provides a method for manufacturing an electrode, comprising applying a first electrode composition to at least a first section of a first surface of a perforated current collector comprising a plurality of holes using a dry coating process, wherein a mean hole opening area of the plurality of holes on the first surface differs from a mean hole opening area of the plurality of holes on a second surface of the perforated current collector, wherein the second surface is in an opposite side to the first surface of the current collector. According to some embodiments, the mean hole opening area of the plurality of holes on the first surface is at least about 20% larger than the mean hole opening area of the plurality of holes on the second surface.

[0086] According to some embodiments, the present invention provides a method for manufacturing an electrode, comprising applying a first electrode composition to at least a first section of a first surface of a perforated current collector comprising a plurality of holes using a dry coating process, wherein a mean hole opening area of the plurality of holes on the first surface differs from a mean hole opening area of the plurality of holes on a second surface of the perforated current collector by at least about 20%, wherein the second surface is in an opposite side to the first surface of the current collector.

[0087] According to some embodiments, there is provided a method for manufacturing an electrode, comprising applying a first electrode composition to at least a first sectionof a first surface of a perforated current collector comprising a plurality of holes, wherein a mean hole opening area of the plurality of holes on the first surface differs from a mean hole opening area of the plurality of holes on a second surface of the perforated current collector, by at least about 20%, and wherein the first electrode composition contains less than about 10% wt. of a solvent, based on the total weight of the first electrode composition.

[0088] According to some embodiments, the electrode is for an energy storage and / or generation device. Each possibility represents a separate embodiment of the invention. According to some embodiments, the electrode is a cathode. According to some embodiments, the electrode is for a battery. According to some embodiments, the electrode is for a lithium-ion battery.

[0089] According to some embodiments, the first section of the first surface is perforated. According to some embodiments, the first surface is perforated.

[0090] According to some embodiments, the mean hole opening area of the plurality of holes on the first surface is at least about 20% larger than the mean hole opening area of the plurality of holes on the second surface. In further embodiments, the mean hole opening area of the plurality of holes on the first surface is at least about 25% larger than the mean hole opening area of the plurality of holes on the second surface.

[0091] According to some embodiments, the mean hole opening area on the first surface ranges from about 2,000 pm2to about 0.15 mm2, including each value and subrange within the specified range. In further embodiments, the mean hole opening area on the first surface ranges from about 5,000 pm2to about 30,000 pm2. In certain embodiments, the mean opening area on the first surface is about 13,000 pm2.

[0092] According to some embodiments, the mean hole opening area on the second surface ranges from about 1,500 pm2to about 0.12 mm2, including each value and subrange within the specified range. In further embodiments, the mean hole opening area on the second surface ranges from about 4,000 pm2to about 25,000 pm2. In certain embodiments, the mean opening area is about 10,000 pm2.

[0093] According to some embodiments, the plurality of holes on the first surface have a mean opening size ranging from about 50 pm to about 500 pm, including each value and sub-range within the specified range. In further embodiments, the mean openingsize on the first surface ranges from about 80 |am to about 200 |am. In certain embodiments, the mean opening size on the first surface is about 130 pm.

[0094] According to some embodiments, the plurality of holes on the second surface have a mean opening size ranging from about 40 pm to about 400 pm, including each value and sub-range within the specified range. In further embodiments, the mean opening size on the second surface ranges from about 65 pm to about 150 pm. In certain embodiments, the mean opening size on the second surface is about 115 pm.

[0095] The plurality of holes of the perforated current collector may be arranged in a seamless repeating perforation pattern. According to some embodiments, the seamless repeating perforation pattern spans over at least 90% of the first surface of the perforated current collector. According to some embodiments, the seamless repeating perforation pattern spans over at least 90% of the first section of the perforated current collector.

[0096] According to some embodiments, the first section spans over at least 70% of the first surface. According to some embodiments, the first section spans over at least 80% of the first surface. According to some embodiments, the first section spans over at least 90% of the first surface. According to some embodiments, the first section spans over at least 95% of the first surface.

[0097] According to some embodiments, the method comprises applying the first electrode composition to at least the first surface of the perforated current collector. According to some embodiments, the method comprises applying the first electrode composition to the entire first surface of the perforated current collector.

[0098] According to some embodiments, a hole pitch ranges from about 100 pm to about 1000 pm, including each value and sub-range within the specified range. In further embodiments, the hole pitch ranges from about 250 pm to about 650 pm. In further embodiments, the hole pitch ranges from about 250 pm to about 350 pm. In additional embodiments, the hole pitch ranges from about 300 pm to about 400 pm. In some embodiments, the hole pitch ranges from about 600 pm to about 700 pm.

[0099] According to some embodiments, an open area of the perforated current collector ranges from about 1% to about 40%, including each value and sub-range within the specified range. In further embodiments, the open area ranges from about3% to about 7%. In certain embodiments, the open area ranges from about 10% to about 20%. In additional embodiments, the open area ranges from about 20% to about 30%.

[0100] According to some embodiments, an open area of the first section ranges from about 1% to about 40%, including each value and sub-range within the specified range. In further embodiments, the open area ranges from about 3% to about 7%. In certain embodiments, the open area ranges from about 10% to about 20%. In additional embodiments, the open area ranges from about 20% to about 30%.

[0101] According to some embodiments, an open area of the first surface ranges from about 1% to about 40%, including each value and sub-range within the specified range. In further embodiments, the open area ranges from about 3% to about 7%. In certain embodiments, the open area ranges from about 10% to about 20%. In additional embodiments, the open area ranges from about 20% to about 30%.

[0102] The plurality of holes of the perforated current collector may have a shape selected from the group consisting of a circular, essentially circular, elliptical, oval, polygonal, rounded polygonal, irregular shape, and any combination thereof. Each possibility represents a separate embodiment of the invention.

[0103] According to some embodiments, the perforated current collector has a thickness ranging from about 4 pm to about 30 pm, including each value and sub-range within the specified range.

[0104] The perforated current collector may include a metal selected from the group consisting of aluminum, copper, nickel, stainless steel, silver, zinc, tin, iron, titanium, and any combination or alloy thereof. In certain embodiments, the metal is aluminum. Each possibility represents a separate embodiment of the invention.

[0105] It is to be understood that references to “electrode composition(s)” are intended to refer to the first electrode composition, the second electrode composition, and / or to the combination thereof.

[0106] Application of the electrode composition(s) may be performed in a roll-to-roll system. The application of the electrode composition may include laminating the first electrode composition and the perforated current collector between a pair of rollers, wherein the first surface of the current collector faces the first electrode composition. In some embodiments, the current collector has a second surface opposite the firstsurface. The method may further include applying a second electrode composition to a second section of second surface of the perforated current collector.

[0107] According to some embodiments, the dry coating process includes simultaneously laminating the first electrode composition, a second electrode composition, and the perforated current collector between the pair of rollers, wherein the first surface of the current collector faces said first portion, and the second surface of the current collector faces said second portion. Lamination may be performed by applying a press force of about 20 kN to about 200 kN. In some embodiments, the lamination is performed by applying a press force of about 60-150 kN. Thus, according to some embodiments, the lamination comprises applying pressure so that the first electrode composition and current collector are pressed one against the other.

[0108] The first electrode composition may be present in a form of a film. According to some embodiments, the first electrode composition contains less than about 10 wt% of the solvent, based on the total weight of the first electrode composition. In certain embodiments, the first electrode composition contains less than about 1 wt% of the solvent.

[0109] The first electrode composition(s) may include an electrode active material selected from the group consisting of lithium nickel manganese cobalt oxide (NMC), lithium iron phosphate (LFP), lithium iron manganese phosphate, lithium nickel manganese oxide, lithium cobalt oxide, lithium nickel cobalt aluminum oxide, lithium cobalt aluminum oxide, lithium titanium oxide, sulfur, lithium sulfide, graphite, silicon oxide, and any combination thereof. Each possibility represents a separate embodiment of the invention. In some embodiments, lithium nickel manganese cobalt oxide has a nickel content of at least about 80 at% based on the total weight of nickel manganese cobalt.

[0110] The electrode active material may be present in the electrode composition(s) in a weight percent ranging from about 90 wt% to about 100 wt%, based of the total weight of the electrode composition(s).

[0111] In some embodiments, the first electrode composition comprises a binder. The binder may be selected from the group consisting of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), cellulose and any combination and derivative thereof. The binder may be present in the electrode composition(s) in a weight percent of 2 wt%or less, based on the total weight of the electrode composition(s). The binder may be present in the electrode composition(s) in a fibrilized form. In some embodiments, the binder comprises particles having a mean particle size below about 20 pm.

[0112] The electrode composition(s) may be obtained by dry mixing components of the electrode composition(s) and subjecting an obtained dry mixture to a fibrilization process, which is optionally followed by grinding and / or sieving.

[0113] A thickness of the first electrode composition applied to at least the first section of the first surface of the perforated current collector may range from about 5 pm to about 250 pm, including each value and sub-range within the specified range.

[0114] According to some embodiments, the method comprises applying a second electrode composition to at least a second section of a second surface of the perforated current collector. According to some embodiments, the second surface is in an opposite side to the first surface of the current collector.

[0115] According to some embodiments, the second section of the second surface is perforated. According to some embodiments, the second surface is perforated.

[0116] According to some embodiments, the method comprises applying the second electrode composition to the second surface of the perforated current collector. According to some embodiments, the method comprises applying the second electrode composition to essentially to the entire second surface of the perforated current collector.

[0117] According to some embodiments, the second section spans over at least 70% of the second surface. According to some embodiments, the second section spans over at least 80% of the second surface. According to some embodiments, the second section spans over at least 90% of the second surface. According to some embodiments, the second section spans over at least 95% of the second surface.

[0118] According to some embodiments, the method comprises applying the first electrode composition to at least the first surface of the perforated current collector.

[0119] According to some embodiments, the second electrode composition is essentially the same as the first electrode composition.

[0120] According to some embodiments, the second electrode composition contains less than about 10 wt% of the solvent, based on the total weight of the second electrodecomposition. In certain embodiments, the second electrode composition contains less than about 1 wt% of the solvent.

[0121] The second electrode composition may include an electrode active material selected from the group consisting of lithium nickel manganese cobalt oxide (NMC), lithium iron phosphate (LFP), lithium iron manganese phosphate, lithium nickel manganese oxide, lithium cobalt oxide, lithium nickel cobalt aluminum oxide, lithium cobalt aluminum oxide, lithium titanium oxide, sulfur, lithium sulfide, graphite, silicon oxide, and any combination thereof. In some embodiments, lithium nickel manganese cobalt oxide has a nickel content of at least about 80 at% based on the total weight of nickel manganese cobalt.

[0122] The electrode active material may be present in the second electrode composition in a weight percent ranging from about 90 wt% to about 100 wt%, based of the total weight of the second electrode composition.

[0123] According to some embodiments, second electrode composition comprises a binder. The binder may be selected from the group consisting of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), cellulose and any combination and derivative thereof. The binder may be present in the second electrode composition in a weight percent of 2 wt% or less, based on the total weight of the second electrode composition. The binder may be present in the second electrode composition in a fibrilized form. In some embodiments, the binder comprises particles having a mean particle size below about 20 pm.

[0124] The second electrode composition may be obtained by dry mixing components of the second electrode composition and subjecting an obtained dry mixture to a fibrilization process, which is optionally followed by grinding and / or sieving.

[0125] A thickness of the second electrode composition applied to the second section of the second surface of the perforated current collector may range from about 5 pm to about 250 pm, including each value and sub-range within the specified range.

[0126] According to some embodiments, the second electrode composition is the same as the first electrode composition.According to some embodiments, the second electrode composition is provided in the form of a film. According to some embodiments, each one of the first electrode composition and the second electrode composition is provided in the form of a film.

[0127] According to some embodiments, the application of the second electrode composition to the second section is performed in a roll-to-roll system. According to some embodiments, the application comprises laminating the perforated current collector and second electrode composition between a pair of rollers. According to some embodiments, the application of the first electrode composition and the second electrode composition is performed together in a roll-to-roll system, and comprises laminating the perforated current collector and the electrode compositions between a pair of rollers. According to some embodiments, upon the simultaneous lamination the perforated current collector is positioned between the first electrode composition and the second electrode composition films.

[0128] According to some embodiments, the lamination comprises applying pressure so that current collector is pressed between the first and second electrode compositions.

[0129] According to some embodiments, upon application of both the first electrode composition and the second electrode composition to the perforated current collector, at least 80% of the total surface of the perforated current collector becomes covered by the electrode compositions. According to some embodiments, upon application of both the first electrode composition and the second electrode composition to the perforated current collector, at least 90% of the total surface of the perforated current collector becomes covered by the electrode compositions. According to some embodiments, upon application of both the first electrode composition and the second electrode composition to the perforated current collector, at least 95% of the total surface of the perforated current collector becomes covered by the electrode compositions. According to some embodiments, upon application of both the first electrode composition and the second electrode composition to the perforated current collector, at least 97% of the total surface of the perforated current collector becomes covered by the electrode compositions.

[0130] According to some embodiments, upon application of both the first electrode composition and the second electrode composition to the perforated current collector the first electrode composition contacts the second electrode composition through atleast some of the plurality of holes. According to some embodiments, upon application of both the first electrode composition and the second electrode composition to the perforated current collector the first electrode composition contacts the second electrode composition through at least 80% of the plurality of holes. According to some embodiments, upon application of both the first electrode composition and the second electrode composition to the perforated current collector the first electrode composition contacts the second electrode composition through at least 90% of the plurality of holes. According to some embodiments, upon application of both the first electrode composition and the second electrode composition to the perforated current collector the first electrode composition contacts the second electrode composition through at least 95% of the plurality of holes.

[0131] According to some embodiments, upon application of the first electrode composition or both the first electrode composition and the second electrode composition to the perforated current collector the first electrode composition and the second electrode composition occupy at least 50% of a total volume of the plurality of holes. According to some embodiments, upon application of the first electrode composition or both the first electrode composition and the second electrode composition to the perforated current collector the first electrode composition and the second electrode composition occupy at least 80% of a total volume of the plurality of holes. According to some embodiments, upon application of the first electrode composition or both the first electrode composition and the second electrode composition to the perforated current collector the first electrode composition and the second electrode composition occupy at least 90% of a total volume of the plurality of holes. According to some embodiments, upon application of the first electrode composition or both the first electrode composition and the second electrode composition to the perforated current collector the first electrode composition and the second electrode composition occupy at least 95% of a total volume of the plurality of holes.

[0132] According to some embodiments, the method further comprises cutting the dry-coated current collector to form a plurality of electrodes.

[0133] Further provided is an electrode prepared by the method disclosed in the aspect and embodiments hereinabove.In some embodiments, the thickness of the first electrode composition on the first surface is at least about 5% lower than the thickness of the second electrode composition on the second surface of the perforated current collector. In some related embodiments, the mean hole opening area of the plurality of holes on the first surface is at least about 20% larger than the mean hole opening area of the plurality of holes on the second surface.

[0134] According to some embodiments, the thickness of the first electrode composition on the first section of the first surface is at least about 5% lower than the thickness of the second electrode composition on the second section of the second surface of the perforated current collector. In some related embodiments, the mean hole opening area of the plurality of holes on the first section of the first surface is at least about 20% larger than the mean hole opening area of the plurality of holes on the second section of the second surface.

[0135] According to some embodiments, at least about 90% of a total volume of the plurality of holes of the perforated current collector in said electrode is filled by the electrode composition(s).

[0136] The volumetric density of the first electrode composition on the first surface and / or the volumetric density of the second electrode composition on the second surface may be at least about 3.1 g / cm3. In some embodiments, the volumetric density of the first electrode composition on the first surface and / or the volumetric density of the second electrode composition on the second surface is at least about 3.3 g / cm3. In certain embodiments, the volumetric density of the first electrode composition on the first surface and / or the volumetric density of the second electrode composition on the second surface is at least about 3.5 g / cm3.

[0137] The volumetric density of the first electrode composition on the first section and / or the volumetric density of the second electrode composition on the second section may be at least about 3.1 g / cm3. In some embodiments, the volumetric density of the first electrode composition on the first section and / or the volumetric density of the second electrode composition on the second section is at least about 3.3 g / cm3. In certain embodiments, the volumetric density of the first electrode composition on the first section and / or the volumetric density of the second electrode composition on the second section is at least about 3.5 g / cm3.According to some embodiments, the electrode formed by the present method is substantially flat.

[0138] BRIEF DESCRIPTION OF THE FIGURES

[0139] Some examples of the invention are described herein with reference to the accompanying figures. The description, together with the figures, makes apparent to a person having ordinary skill in the art how some examples may be practiced. The figures are for the purpose of illustrative description and no attempt is made to show structural details of an example in more detail than is necessary for a fundamental understanding of the invention. For the sake of clarity, some objects depicted in the figures are not to scale.

[0140] In the Figures:

[0141] Figure 1 shows a schematic representation of a cross-sectional view of a three-dimensional (3D) perforated current collector, in accordance with some embodiments of the present invention.

[0142] Figure 2A shows a schematic representation of a cross-sectional view of an electrode during a dry coating manufacturing process, wherein the electrode includes a perforated current collector having a flat surface (comparative example).

[0143] Figure 2B shows a schematic representation of a cross-sectional view of an electrode during a dry coating manufacturing process, wherein the electrode includes a perforated current collector having a nonplanar surface, in accordance with some embodiments of the present invention.

[0144] Figure 3 shows an optical microscopy image of a perforated current collector having a nonplanar surface that was used in the electrode manufacturing process.

[0145] Figure 4 graphically shows electrochemical testing results of a coin cell containing a cathode based on a perforated current collector having a nonplanar surface (squares) and of a coin cell containing a cathode based on a perforated current collector having a flat surface (triangles; comparative example).

[0146] Figure 5 schematically illustrates a top view of a section of perforated current collector, according to some embodiments of the present invention.

[0147] Figure 6A schematically represents a cross-sectional view of perforated current collectors having straight-sided, slanted holes profile with different hole openings onthe opposite surfaces thereof, in accordance with some embodiments of the present invention.

[0148] Figure 6B schematically represents a cross-sectional view of perforated current collectors having concave tapered holes profile with different hole openings on the opposite surfaces thereof, in accordance with some embodiments of the present invention.

[0149] Figure 6C schematically represents a cross-sectional view of perforated current collectors having convex tapered holes profile with different hole openings on the opposite surfaces thereof, in accordance with some embodiments of the present invention.

[0150] Figure 6D schematically represents a cross-sectional view of perforated current collectors having stepped holes profile with different hole openings on the opposite surfaces thereof, in accordance with some embodiments of the present invention.

[0151] Figure 7 graphically shows electrochemical testing results of a coin cell containing a cathode based on a perforated current collector having slanted hole walls (squares) and of a coin cell containing a cathode based on a perforated current collector having essentially straight hole walls (triangles; comparative example).

[0152] Figure 8A shows an optical microscopy image of a one-sided coated electrode manufactured through a dry-coating process using a perforated current collector having a planar surface and cylindrical holes.

[0153] Figure 8B shows an optical microscopy image of a one-sided coated electrode manufactured through a dry-coating process using a perforated current collector having a planar surface and conical holes.

[0154] Figure 8C shows an optical microscopy image of a one-sided coated electrode manufactured through a dry-coating process using a perforated current collector having a non-planar surface and conical holes.

[0155] Figure 8D shows an optical microscopy image of a dual-sided coated electrode manufactured through a dry-coating process using a perforated current collector having a planar surface and cylindrical holes.

[0156] Figure 8E shows an optical microscopy image of a dual-sided coated electrode manufactured through a dry-coating process using a perforated current collector having a non-planar surface and conical holes.Figure 9 is a schematic illustration of a coating system for producing a singlesided electrode.

[0157] Figure 10 is a schematic illustration of a coating system for producing a double -sided electrode.

[0158] DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0159] The present invention provides a perforated current collector for use in the dry coating process of manufacturing electrodes for energy storage and generation devices, such as lithium-ion batteries. The perforated current collector of the present invention is designed to address the challenges of dry coating processes by facilitating improved adhesion of the electrode composition to the current collector. In particular, the adhesion may be improved by applying an electrode composition to at least a first section of a first surface of a perforated current collector comprising a plurality of holes, wherein at least a portion of the plurality of holes have an inner wall surface that forms a non-right angle with a longitudinal plane of the current collector. As dry coating processes typically utilize electrode compositions in the form of a film applied to a current collector, the orientation of the hole walls relative to the longitudinal plane of the current collector plays a critical role. When the hole walls are not perpendicular to this plane, a non-right angle is formed between the hole walls and the electrode composition film. Advantageously, this configuration enhances the packing density of the active material within the holes, improving its anchoring for single-sided electrodes. Additionally, for double side-coated electrodes, this orientation increases the mechanical binding of the active material on opposite surfaces of the current collector through the holes, further strengthening the electrode structure.

[0160] The present invention provides a method for manufacturing an electrode, particularly for an energy storage and / or generation device, using a dry coating process and a perforated current collector. The method is designed to address the challenges of achieving sufficient electrode material adhesion to a current collector, inherent in dry coating processes. The method is based on the general inventive concept of configuring the perforated current collector such that the inner wall surfaces of the perforations are oriented at a non-right angle relative to a longitudinal plane of the collector. This specific geometry ensures that when an electrode composition is applied, it engages thehole walls at an oblique angle, thereby enhancing mechanical interlocking and creating a more robust and densely packed electrode structure.

[0161] There is thus provided a method for manufacturing an electrode for an energy storage and / or generation device, including applying an electrode composition to at least a first section of a first surface of a perforated current collector comprising a plurality of holes, using a dry coating process. At least a portion of the plurality of holes of the current collector have an inner wall surface that forms a non-right angle with a longitudinal plane of the current collector. In other words, the inner wall surface of the plurality of holes is not perpendicular to the longitudinal plane of the current collector.

[0162] The term “non-right angle”, as used herein, refers in some embodiments, to an angle that is different than about 90°, such as an angle ranging from about 0° to about 85° or from about 95° to about 180°. It is to be understood that the angle value depends on the direction from which it is measured, such that an angle of e.g., 30° defines the same hole orientation as its supplementary angle 150°, such that referring to a certain angle also encompasses the supplementary angle thereof.

[0163] The angle between the inner wall surface of the holes and the longitudinal plane of the current collector thus may range from about 0° to about 85° or from about 95° to about 180°. In some embodiments, the angle ranges from about 10° to about 90°, from about 20° to about 80°, from about 30° to about 70°, or from about 40° to about 60°.

[0164] The portion of the plurality of holes having an inner wall surface that forms a non-right angle with a longitudinal plane of the current collector may range from about 20% to about 100%. In some embodiments, at least 20% of the plurality of holes of the current collector have an inner wall surface that forms a non-right angle with a longitudinal plane of the current collector, at least 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% of the plurality of holes of the current collector have an inner wall surface that forms a non-right angle with a longitudinal plane of the current collector. In certain embodiments, essentially every hole of the current collector has an inner wall surface that forms a non-right angle with a longitudinal plane of the current collector.

[0165] The current collector for use in electrode preparation is typically provided in the form of a thin film rolled onto a spool for ease of handling during the manufacturing process. During production, the roll is unwound, and the current collector is processedthrough various steps, such as electrode composition application. Once the electrode is prepared, the coated current collector is typically re-rolled for intermediate storage or directly fed into a cutting process. The continuous film is then precision-cut into electrode sheets or strips of predetermined dimensions suitable for battery assembly.

[0166] Depending on the context, the term "current collector," as used herein, may refer to the continuous foil (either in its wound or unwound state during processing) or to the cut pieces prepared for electrode assembly. It may also refer to the current collector as part of the fully assembled electrode within a battery. The longitudinal axis of the current collector is defined as the axis running along the length of the current collector foil in its continuous or unwound state, corresponding to the direction of its primary rolling or unwinding during processing. The longitudinal plane is a plane that is parallel to the longitudinal axis and extends along the width and length of the current collector, representing its flat surface when unwound. Said axis and plane may serve as a reference for describing surface features, orientations, and the alignment of materials or patterns applied to the current collector.

[0167] In order to form a non-right angle between the hole walls and the longitudinal plane of the current collector, the perforated current collector may have a non-flat (or non-planar) surface, such that the holes are distributed along tilted or curved lines that are not parallel to the longitudinal plane of the current collector. Essentially the same non-right angle is also formed between the hole walls of the 3D perforated current collector and the electrode composition. It was demonstrated that a perforated current collector, characterized by its three-dimensional structure allows for enhanced mechanical interlocking of the electrode material and improved packing density within the perforations when employing a dry coating process, even if the 3D structure is not maintained. During the dry coating process, the degree of deviation of the perforated current collector from a planar surface may be partially reduced or flattened as a result of applied mechanical forces. Without wishing to being bound by theory or mechanism of action, it is contemplated that this reduction in surface topography can further enhance the electrode packing and interfacial contact between the electrode composition and the current collector, including within and around the perforations, which may further improve mechanical interlocking, electrical connectivity, and overall electrode integrity. The batteries containing electrodes based on the non-planarperforated current collector were shown to provide a higher discharge capacity and lower resistance in various charge and discharge cycling modes.

[0168] There is thus provided a method for manufacturing an electrode for an energy storage and / or generation device, including applying an electrode composition(s) to at least a first surface of a perforated current collector comprising a plurality of holes, using a dry coating process, wherein the first section of the first surface is non-planar.

[0169] According to some embodiments, the method alternatively or additionally achieves the required non-right- angle orientation through the specific geometry of the holes themselves. This is accomplished by utilizing a perforated current collector wherein a mean hole opening area on a first surface differs from a mean hole opening area on a second, opposite surface. The resulting tapered geometry of the holes, which inherently provides slanted inner walls, ensures the desired non-right- angle contact with the applied electrode composition. This configuration provides a funnelling effect for improved electrode material distribution and compaction, leading to enhanced mechanical anchoring and packing density. It has been found that this design provides an improved anchoring effect, particularly in dual-sided coated electrodes. It has also been discovered that while the use of such tapered holes in a roll-to-roll process may result in uneven electrode composition thickness on opposite sides, this imbalance can be mitigated by the perforated structure of the current collector, for example, by providing improved ionic pathways.

[0170] There is thus provided a method for manufacturing an electrode for an energy storage and / or generation device, including applying an electrode composition(s) to at least a first surface of a perforated current collector comprising a plurality of holes, using a dry coating process, wherein a mean hole opening area of the plurality of holes on the first surface differs from a mean hole opening area of the plurality of holes on a second, opposing, surface by at least about 20%.

[0171] Three-dimensional current collector

[0172] According to some embodiments, the method improves adhesion by applying an electrode composition to at least a first section of a first surface of the perforated current collector. In this configuration, the non-right- angle orientation is achieved because the current collector has a non-planar surface, such that holes are distributed along tilted or curved lines. As dry coating processes typically utilize electrodecompositions in the form of a film, the orientation of the hole walls on this non-planar surface relative to the longitudinal plane of the current collector plays a critical role. When the hole walls are not perpendicular to this plane, a non-right angle is formed between the hole walls and the applied electrode composition film. Advantageously, this configuration enhances the packing density of the active material within the holes, improving its anchoring for single-sided electrodes. Additionally, for double side-coated electrodes, this orientation increases the mechanical binding of the active material on opposite surfaces of the current collector through the holes, further strengthening the electrode structure.

[0173] The perforated current collector may have a nonplanar or non-flat surface, intentionally designed or modified to deviate from a perfectly planar configuration. Such surface may include three-dimensional features that alter the current collector's topography, providing functional advantages in dry electrode manufacturing. The terms "non-planar" and “non-flat”, as used herein, refer to a surface having three-dimensional qualities or having regions with a certain angle relative to the longitudinal plane of the current collector, which is greater than 0° and less than 180°, i.e., tilted regions.

[0174] According to some embodiments, the perforated current collector has a first surface and a second (opposite) surface. A shortest distance between the first surface and the second surface may be referred to as a local thickness of the perforated current collector (which is also the thickness of the current collector prior to its surface modification). In some embodiments, both the first surface and the second surface are non-flat. In further embodiments, the second surface is essentially parallel to the first surface. In yet further embodiments, the first surface conforms to the first surface. In additional embodiments, the entire thickness of the perforated current collector is perturbed to form the current collector into a 3D-structured foil.

[0175] As used herein, the term "3D foil", "3D-formed foil", “3D-shaped foil”, or "3D surface", may be used interchangeably with the term "non-flat foil / surface" and refers generally to a foil that has at least one non-flat surface. It is to be understood that the terms "3D foil", "3D-formed foil", “3D-shaped foil”, or "3D surface" are not intended to be limited by, or tied to, any specific manufacturing process unless expressly stated.

[0176] The non-flat surface(s) can be achieved through several methods, including but not limited to:Embossing: The mechanical deformation of the current collector foil to create raised or recessed features, such as peaks, ridges, valleys, dimples, or depressions, distributed in a predetermined pattern or random configuration. Embossing involves mechanically pressing a patterned tool or die onto the surface of the current collector to create raised and recessed areas. This is typically performed using an embossing press or stamping machine. For example, a patterned die may be created with the desired texture or features, such as peaks, valleys, or dimples. The current collector is then placed between the die and a backing plate and pressure is applied, deforming the current collector to replicate the pattern of the die.

[0177] Roll Embossing: A process which involves passing the current collector foil between a patterned roller and a counter roller to create a three-dimensional texture on its surface or to transform the planar foil into a three-dimensional shape. The patterned roller impresses a specific design, such as isolated peaks and depressions, or continuous ridges and valleys, into the foil, while the counter roller ensures uniform pressure and material support. Alternatively, a male and female patterned rollers may be used, for example, when patterns are desired on both sides of the foil or when exact alignment of raised and recessed areas on opposite sides are required. The pattern depth and consistency or the degree of deviation from the planar shape may be adjusted by varying the rollers geometry, rotation speed and / or pressure.

[0178] Corrugation: The creation of alternating parallel ridges and grooves across the surface of the current collector, which may run in straight, curved, or wave-like patterns. Corrugation involves passing the current collector through a set of rollers that alternately compress and release the material to form a wavy pattern. Corrugation is typically performed by feeding the current collector into a corrugating machine with two interlocking rollers. Each roller has ridges and grooves that force the material into a zigzag shape. The rollers apply consistent pressure as the collector passes through, forming uniform corrugation. The degree of corrugation (height and pitch) can be adjusted by varying the roller geometry and / or pressure.

[0179] Patterned Rolling: A process in which the current collector is passed through rollers with engraved patterns, imprinting the surface with a series of repetitive or irregular patterns that produce a non-flat topography or form the foil into a three-dimensional shape. The patterns are formed as part of the rolling process, oftenaccompanied by thickness reduction or reshaping of the foil. The pattern depth and consistency are controlled by adjusting the roller pressure and speed.

[0180] Texturing: The introduction of fine or coarse irregularities on the surface through chemical etching, electrolytic etching, electrodeposition, sandblasting, or other mechanical or chemical means, resulting in a roughened or patterned surface. For example, mechanical texturing may be performed by exposing the current collector to abrasive particles (e.g., sand or aluminum oxide) blasted at high speed through a nozzle. The impact of the particles roughens the surface, creating small indentations and increasing surface roughness. Chemical Etching may be performed by dipping the current collector into an etching solution (commonly acid-based) that selectively removes material from the surface. The depth and texture of the surface irregularities that are forced by chemical etching are controlled by the exposure time, composition, concentration and / or temperature of the etching solution.

[0181] Surface Profiling: The intentional design of varying elevations across the surface, which can include features such as bumps, protrusions, or micro-pyramids, providing distinct regions of high and low surface areas. Surface profiling is typically done using mechanical machining techniques or precision stamping to create said raised features. Surface profiling may be performed by using a stamping press or machining tool with the desired profile pattern (such as micro-pyramids or bumps) to imprint the current collector. The current collector is then passed through a series of dies or cutting tools that shape the surface with varying elevations. The surface features can be adjusted based on the required depth or height of the profile.

[0182] Laser Ablation: The use of laser technology to selectively remove material from the surface, creating pits, grooves, or other non-planar features that alter the surface morphology. A laser system (such as CO2 or fiber lasers) may be programmed to selectively target areas of the current collector. The laser pulses vaporize or burn away material to create the desired pattern. The process is highly controlled to ensure precision, with the depth of the ablation controlled by adjusting the laser power and pulse duration.

[0183] The surface modification technique, such as embossing, corrugation, texturing, surface profiling, or laser ablation can be selected based on the desired 3D pattern of the perforated current collector.The non-flat surface may be uniform or non-uniform. The term “uniform nonflat surface”, as used herein, refers to a surface that exhibits a consistent pattern of features, such as ridges, grooves, or bumps, that are evenly distributed across the entire surface of the current collector. This type of surface typically involves repetitive and predictable features that maintain similar dimensions and spacing throughout, such as, for example, a corrugated surface, wherein alternating ridges and valleys are evenly spaced, providing a regular wavy pattern or an embossed surface, wherein features such as dimples, peaks, or depressions are uniformly distributed.

[0184] In some specific embodiments, the term "3D foil", "3D-formed foil", “3D-shaped foil” or "3D surface" refers specifically to a foil having embossed elements on at least one surface thereof. In some embodiments, the 3D perforated current collector is embossed, i.e., has embossed elements. The term “embossed elements”, as used herein, refers in some embodiments, to a plurality of both embossed and debossed textural elements that bestow a patterned texture, regular surface roughness and / or regular surface undulations. An embossed current collector may combine both embossment and debossment elements, “dual-level embossing" and / or "dual-level debossing", referring to the creation of both raised and recessed textural elements within the same design on a material. In some embodiments, the embossed elements are regular in size, shape, spacing, and relative orientation. According to some embodiments, the embossed elements are arranged in a seamless repeating pattern.

[0185] As used herein, the term “seamless repeating pattern”, abbreviated herein to SRP, refers to a pattern that spans an undefined and unlimited surface without visible transitions or boundaries. An SRP is an endless repeating pattern of textural elements, that consists of repeating elements arranged in a two-dimensional format, such as a geometric shape or a decorative design. An SRP continues indefinitely in all directions, creating a seamless visual effect. This type of pattern is often used in textiles, wallpaper, flooring, and other decorative materials, as well as in graphic design, packaging, and branding. An SRP can be defined by a repeating pattern unit, whereas placing a plurality of such units intimately adjacent (juxtaposed) to each other will afford the SRP. The repeating unit is referred to herein as a tile or a motif. The motif is defined by one or more textural elements, whereas each motif blends into neighbouring motifs to achieve the SRP.The term “textural element”, as used herein, is meant to encompass both embossed elements and perforations (i.e., holes or through holes). The SRP may thus be a seamless repeating embossing pattern or a seamless repeating perforation pattern. In some embodiments, the current collector includes both a seamless repeating perforation pattern and a seamless repeating embossing pattern.

[0186] In some embodiments, the SRP is afforded by a periodic tiling, whereas some embodiments include regular tiling with regular polygonal tiles, all having the same shape, and some embodiments include semiregular tiling with regular tiles of more than one textural element shape and with every corner identically arranged.

[0187] The terms “motif’ or “tile”, as used herein, refer to the smallest and simplest single textural element, or non-repeating group of textural elements, the repetition of which forms and defines the SRP. In the context of the present invention, a motif is closely related to a unit cell in a 3D lattice (a crystal / lattice), whereas the SRP is formed by repeating the motif in the plane to any direction on the plane. Within a motif there can be one textural element, or more than one textural elements. In some embodiments, the motif includes more than one textural elements that relate to one another by symmetry operations in the 2D plane, such as translation, rotation and reflection transformation operations. In some embodiments, the motif includes more than one textural elements that are arranged non- symmetrically with respect to one-another, or more than one textural elements having different size / shape. A flat plane, or SRP, can be fully tiled (covered) with triangular, rectangular and hexagonal polygons (tiles), each having one or more textural elements arranged within. Rectangular and hexagonal tiles can be placed using the same tile orientation (only translation, no rotation), while triangular tiles are placed with a 600rotation (translation and rotation).

[0188] An example of a simple motif is a circular embossed or debossed textural element, whereas its SRP can be a square or hexagonal packing. Another example of a simple motif is a circular through hole, whereas its SRP can be a square or hexagonal packing.

[0189] An embossed element can perturb the surface on one side thereof, e.g., the first surface, and be a bulge (e.g., peak) or a depression (e.g., valley), depending on the definition of the opposite sides of the current collector (i.e., whether the first surface is a “top side” or a “bottom side”). Embossed elements may be divided into a group ofisolated elements, such that may form a single local bulge, and a group of extended elements, such that may form a ridge across the foil, ending at the edge of the foil (e.g., a corrugation pattern).

[0190] For example, an embossed element may include a combination of rounded bulges and depressions, which are arranged in a checkmate pattern, i.e., each bulge (other than bulges located at the edges of the current collector) is surrounded by four adjacent depressions and each depression (other than depressions located at the edges of the current collector) is surrounded by four adjacent bulges. Additionally, a embossed element may include a combination of rounded bulges and depressions, which are arranged in a hexagonal pattern, i.e., each bulge (other than bulges located at the edges of the current collector) is surrounded by three adjacent depressions and each depression (other than depressions located at the edges of the current collector) is surrounded by three adjacent bulges. Alternatively, an embossed element can span any length with respect to the size of the current collector, namely a valley or a peak can run from edge to edge while forming a part of an SRP of parallel waves. The longitudinal axis of the extended embossed element may be oriented perpendicular to the longitudinal axis of the current collector or may be tilted at any angle with respect to the longitudinal axis, as well as parallel to the longitudinal axis of the current collector.

[0191] In some embodiments, the isolated embossed elements are aligned in straight lines. In some embodiments, the isolated embossed elements are aligned in tilted lines, which are tilted with respect to the longitudinal axis of the current collector foil or one of its edges. In some embodiments, the isolated embossed elements are arranged in tiles / motifs.

[0192] Non-limiting examples of embossed elements include peaks, protrusions, ridges, bulges, bumps, creases, valleys, and depressions. In some embodiments, the embossed elements comprise periodically alternating peaks and valleys. In some embodiments, the embossed elements comprise periodically alternating round bulges and depressions.

[0193] The shape of an isolated embossed element may be defined by the “footprint” of the element on the surface of the current collector, e.g., as it would look like fromabove or beneath the current collector. For example, a simple round bulge / depression is an example of an isolated embossed element having a round (circular) shape.

[0194] The shape of an extended embossed element may be defined by the crosssection of the current collector perpendicular to the general direction of the element and to the longitudinal plane of the current collector. For example, undulating parallel ridges / valleys, or parallel wave in the shape of a sine (sinusoidal wave) are examples of extended embossed elements.

[0195] The embossed element can perturb the first surface and the second surface of the current collector in the same or different manner. In other words, the shape or footprint of the embossed elements of the first surface may be the same or different than on the second surface of the current collector.

[0196] The shape of an isolated or extended embossed element can be further assessed by examining its cross-sectional profile (perpendicular to the longitudinal plane of the current collector), considering parameters such as amplitude, waveform, wavelength, and symmetry. For example, a waveform of the isolated embossed elements can vary from simple sinusoidal forms to more complex shapes like triangular, rectangular, or trapezoidal forms, wherein the edges of the embossed element having said more complex shapes may be sharp or bevelled. In the case of the extended embossed elements, the waveform may also be sinusoidal or non-sinusoidal, including, inter alia, a square wave, triangular wave, sawtooth wave, rectangular wave, and trapezoidal wave. Isolated embossed elements may exhibit symmetry if their shape and size are consistent across the surface or asymmetry if the shape varies, wherein the extended embossed elements are typically symmetric along or across the longitudinal plane of the current collector.

[0197] The 3D pattern of the perforated current collector may further be defined by the height of the 3D pattern (e.g., embossing pattern), a total thickness of the three-dimensional current collector, and / or the pitch of the 3D pattern.

[0198] The height (or amplitude) of an embossed element refers to the vertical distance from a longitudinal plane of the current collector to the highest point of the embossed element, when the embossed element is a bulge (or a peak), or to the vertical distance from the longitudinal plane to the lowest point of the embossed element, when the embossed element is a depression (or a valley). The vertical distance between thehighest point of the embossed element that is a bulge (or peak) and the lowest point of the embossed element that is a depression (or valley) can be referred to as a total thickness of the three-dimensional current collector (also termed herein “3D thickness” and “embossing thickness”). The 3D thickness may also be referred to as a peak to valley vertical distance, which is the vertical distance between the top of a peak and the bottom of an adjacent valley. In this context, a valley is a depression on the surface, and a peak is the bulge between two valleys that rises above the surface.

[0199] The pitch of the embossing pattern refers to the horizontal distance between the centers of two adjacent isolated or extended embossed elements having the same direction of embossing, i.e., either raised above the longitudinal plane or recessed therebelow, along the longitudinal axis of the current collector. For example, the pitch of the embossing pattern may refer to a peak-to-peak horizontal distance (or to a valley -to- valley horizontal distance).

[0200] As used herein, the term “horizontal distance” refers to a distance measured within the longitudinal plane of the current collector (i.e., in a direction parallel to said plane), excluding any vertical component. Unless otherwise indicated, horizontal distance is measured along the longitudinal axis of the current collector.

[0201] As used herein, the term “peak-to-peak horizontal distance” refers to the horizontal distance (as defined above) between the centers of two adjacent embossed elements that are both raised above the longitudinal plane (peaks). By analogy, “valley-to-valley horizontal distance” refers to the horizontal distance between the centers of two adjacent embossed elements recessed below the longitudinal plane (valleys). These distances define the pitch of the embossing pattern.

[0202] Reference is now made to Figure 1, which schematically represents a cross-sectional view of 3D perforated current collector 101 having a seamless repeating embossing and perforation pattern, according to some embodiments of the present invention. 3D perforated current collector 101 has a sinusoidal-like cross-sectional shape that includes a plurality of embossed elements, including alternating bulges 103 and depressions 105, which form a corrugated structure along longitudinal plane A. A plurality of bulges 103 extend above longitudinal plane A, while a plurality of depressions 105 are recessed below it. Current collector 101 further includes a plurality of through-holes 107. In this design, the amplitude of an embossed element B and Crefers to the vertical distance from longitudinal plane A to highest point 103a of bulge 103 and to the vertical distance from longitudinal plane A to lowest point 105a of depression 105, respectively. The total thickness or embossing thickness refers to the vertical distance from highest point 103a of bulge 103 to lowest point 105a of adjacent depression 105, i.e., the distance between the highest and lowest points of the embossed structure or the combination of B and C. Size (i.e., horizontal span at the base) of the embossed element, which is bulge 103 is denoted herein as G. Pitch of the embossing pattern E refers to the horizontal distance between the centers of two adjacent bulges 103.

[0203] Three dimensional (3D) perforated current collector 101 further has first surface 109 and second surface 111 to which the electrode composition may be applied. Distance H between first surface 109 and second surface 111 is the local thickness of the current collector.

[0204] The embossing pattern parameters of the perforated current collector, such as pitch or amplitude, or the 3D thickness of the perforated foil may be measured using various techniques depending on the precision and embossed elements size. One of the common methods is optical microscopy. Using a microscope with calibrated measurement capabilities, the sizes of the embossed elements can be directly measured by visually observing the perforated current collector under magnification. Alternatively, an optical microscope or a scanner may be used along with a specialized image analysis software that analyzes the images obtained with the microscope or scanner and measures the amplitude and pitch of the embossed elements manually or automatically. Additionally, Scanning Electron Microscopy (SEM) that provides high-resolution imaging capabilities, may be used to precisely measure said embossing pattern parameters of the current collector. Both top view and cross-sectional current collector samples can be analyzed by optical and electron microscopy. Furthermore, confocal microscope or a profilometer may be used to provide a precise topographical image without the need to prepare a cross-sectional sample. A confocal microscope can be used to measure the amplitude of an embossed current collector by capturing detailed, high-resolution 3D images that quantify the vertical distance (height) of bulges and depressions and peaks and valleys. A profilometer can measure both the amplitude, pitch, and 3D thickness by scanning the surface of the foil, generating a surface profile that reveals peak-to-valley heights (3D amplitude) and the distance between repeatingcorrugation peaks (pitch), allowing for precise topographical mapping of the current collector.

[0205] The perforated current collector may have a local thickness (the thickness of the current collector prior to embossing) ranging from about 2 pm to about 100 pm. In some embodiments, the local thickness ranges from about 3 pm to about 50 pm. In certain embodiments, the local thickness ranges from about 4 pm to about 30 pm. In further embodiments, the local thickness ranges from about 5 pm to about 20 pm.

[0206] In some embodiments, the ratio of the total thickness of the embossed current collector to the local thickness is at least about 1.1:1, at least about 1.2:1, at least about 1.3:1, at least about 1.4:1, at least about 1.5:1, at least about 1.6:1, at least about 1.7:1, at least about 1.8:1, at least about 1.9:1, at least about 2:1, at least about 2.2:1, at least about 2.3:1, at least about 2.4:1, at least about 2.5:1, at least about 2.6:1, at least about 2.7:1, at least about 2.8:1, at least about 2.9:1, or at least about 3:1. In some embodiments, the ratio of the total thickness of the embossed current collector to the local thickness ranges about 1.1:1 - 10:1, or about 2:1 -9:1, or about 3:1 - 8:1, or about 4:1 - 6:1. Each possibility represents a separate embodiment of the invention. In some embodiments, the total thickness is about 3-8 times larger than the local thickness.

[0207] The total thickness of the embossed current collector (or the peak to valley (or bulge to depression) vertical distance) may range from about 6 pm to about 1,000 pm. In some embodiments, the total thickness ranges from about 10 pm to about 500 pm, from about 15 pm to about 300 pm, from about 20 pm to about 200 pm, from about 30 pm to about 150 pm, or from about 40 pm to about 100 pm. Each possibility represents a separate embodiment of the invention. It should be understood that the above ranges refer to the total thickness of the embossed current collector prior to application of the electrode composition in the dry coating process.

[0208] In some embodiments, the total thickness of the embossed current collector is less than about 500 pm, less than about 250 pm, less than about 100 pm, less than about 90 pm, less than about 80 pm, less than about 70 pm, less than about 60 pm, less than about 50 pm, less than about 40 pm, less than about 30 pm, less than about 20 pm, less than about 15 pm, or less than about 10 pm. In some embodiments, the total thickness is at least about 10 pm, 20 pm, 30 pm, 40 pm, 50 pm, 60 pm, 70 pm, 80 pm, 90 pm,about 100 |am, 150 |am, 200 |am, 300 |am, 400 |am, or at least about 500 |am. Each possibility represents a separate embodiment of the invention.

[0209] The size (diameter, footprint or widest horizonal span at the base of the embossed element) of isolated embossed elements may range from about 10 pm to about 5,000 pm. In some embodiments, the size of an isolated embossed element ranges from about 20 pm to about 2,500 pm, from about 30 pm to about 1,000 pm, from about 40 pm to about 500 pm, or from about 50 pm to about 200 pm. Each possibility represents a separate embodiment of the invention.

[0210] In some embodiments, the size of an isolated embossed element is less than about 400 pm, less than about 350 pm, less than about 300 pm, less than about 250 pm, less than about 200 pm, less than about 150 pm, less than about 100 pm, less than about 90 pm, less than about 90 pm, less than about 80 pm, less than about 70 pm, less than about 60 pm, less than about 50 pm, less than about 40 pm, less than about 30 pm, less than about 20 pm, or less than about 15 pm. Each possibility represents a separate embodiment of the invention.

[0211] In some embodiments, the size of an isolated embossed element is at least about 10 pm, at least about 20 pm, at least about 30 pm, at least about 40 pm, at least about 50 pm, at least about 100 pm, or at least about 200 pm. Each possibility represents a separate embodiment of the invention.

[0212] The pitch of the embossing pattern may range about 10-5000 pm, or about 50-2500 pm, or about 100-1000 pm, or about 250-750 pm, or about 400-600 pm, or about 50-100 pm, or about 100-200 pm, or about 200-300 pm, or about 300-400 pm, or about 400-500 pm, or about 500-600 pm, or about 600-700 pm, or about 700-800 pm, or about 800-500 pm, or about 900-1000 pm. In some embodiments, the pitch of the embossing pattern is less than about 1,000 pm, less than about 750 pm, less than about 500 pm, less than about 250 pm, or less than about 100 pm. In some embodiments, the pitch is at least about 10 pm, about 50 pm, about 100 pm, about 150 pm, about 200 pm, about 300 pm, about 400 pm, about 500 pm, about 600 pm, about 700 pm, about 800 pm, about 900 pm, or at least about 1,000 pm. In some embodiments, the pitch of the embossing pattern is a peak-to-peak (or bulge-to-bulge) horizontal distance along the longitudinal axis of the current collector. In certain embodiments, peak-to-peakhorizontal distance ranges from about 100 |am to about 1000 |am. Each possibility represents a separate embodiment of the invention.

[0213] The holes of a perforated current collector may be distributed throughout the nonplanar surface of the current collector such that at least a portion of the plurality of holes have a hole wall surface that is not perpendicular to the longitudinal plane. Such holes are located within the tilted regions of the current collector surface. For example, if the current collector is embossed, such holes are positioned on the slopes of the peaks and valleys (or bulges or depressions) of the embossed foil instead of being located exactly within the inversion points of the embossed surface (i.e., the highest and lowest points).

[0214] The portion of the plurality of holes located within the tilted regions of the current collector surface may range from about 20% to about 100%, including each value and sub-range within the specified range. In some embodiments, at least 20% of the plurality of holes of the current collector are located within the tilted regions, at least 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% of the plurality of holes of the current collector are located within the tilted regions of the current collector surface.

[0215] The perforated current collector having a nonplanar surface may be designed to have a controlled number of holes that are located within the tilted regions, by adjusting the 3D thickness and horizontal distance between the tilted regions (3D pitch) of the nonplanar surface with respect to the average hole size and distance between adjacent holes of the perforation pattern.

[0216] In some embodiments, the holes of the embossed current collector are smaller and arranged more densely than the embossed elements thereof (e.g., 1.5-100 times smaller). In other words, more than one hole may be included within each embossed element.

[0217] According to the various embodiments of the present invention, the current collector is designed to have a non-flat surface in order to provide such configuration of hole walls orientation relatively to the longitudinal plane of the current collector (and of the applied electrode composition). When a flat perforated current collector is used, the portion of the electrode composition that enters the holes is equal to the diameter of the hole, as the electrode composition is applied in parallel to the hole opening and theelectrode composition comes in contact with the walls of the current collector holes at a right angle. However, without wishing to be bound by any theory of mechanism of action when the perforated current collector is non-planar and the holes are tilted relatively to the electrode composition plane - the electrode composition comes in contact with the walls of the of the current collector holes at an angle that is different than 90°. In such case, the portion of the composition that enters the perforations is longer than the hole opening. This length can be represented by the hypotenuse of a right triangle formed by the angled application. In such configuration, the diameter of the hole may represent the base of this triangle and the angle between the electrode composition surface and the tilted surface of the current collector where the hole is disposed causes the electrode material to stretch into the hole, creating a hypotenuse longer than the hole diameter. In essence, the length of electrode composition entering the hole may essentially equal the hypotenuse. This longer path can affect the distribution and volume of electrode material within the holes, e.g., to provide a denser packing of the active material, thereby improving properties like electrical conductivity and mechanical adhesion.

[0218] Current Collector with Tapered Holes and Hole opening size

[0219] According to the some embodiments of the present invention, the first electrode composition is applied to at least a first surface of a perforated current collector, wherein a mean hole opening area of the plurality of holes on the first surface differs from a mean hole opening area of the plurality of holes on the second surface by at least about 20%. Typically, the first electrode composition is applied in parallel to the longitudinal plane of the current collector. Thus, in the disclosed perforated current collector in which the mean hole opening area of the plurality of holes on the first surface differs from the mean hole opening area of the plurality of holes on the second surface by at least about 20%, the plurality of holes would have slanted walls which surface is not perpendicular to the first electrode composition applied thereto. Compared to a current collector in which the holes are cylindrical and the hole walls are perpendicular to the applied first electrode composition, the disclosed design may enable enhanced material penetration and packing efficiency, resulting in high electrode density.

[0220] The mean opening area of the plurality of holes of the perforated current collector may be selected based on whether the current collector is designated for an anode or a cathode, on the type and properties of the electrode composition(s), and onthe desired battery characteristics. In general, the mean opening area may range from about 20 pm2to about 3 mm2.

[0221] In some embodiments, the mean hole opening area is less than about 1.7 mm2, less than about 0.8 mm2, less than about 0.2 mm2, less than about 50,000 pm2, less than about 30,000 pm2, less than about 18,000 pm2, less than about 13,000 pm2, or less than about 8,000 pm2.

[0222] In some embodiments, the mean hole opening area is at least about 80 pm2, at least about 300 pm2, at least about 1,200 pm2, at least about 2,000 pm2, at least about 5,000 pm2, at least about 7,500 pm2, at least about 13,000 pm2, at least about 18,000 pm2, or at least about 30,000 pm2.

[0223] In some embodiments, the mean hole opening area ranges from about 80 pm2to about 1.7 mm2, or about 300 pm2to about 0.8 mm2, or about 1,200 pm2to about 0.2 mm2, or about 2,000 pm2to about 50,000 pm2, or about 5,000 pm2to about 30,000 pm2, or about 7,500 pm2to about 18,000 pm2.

[0224] According to the principles of the present invention, a mean hole opening area of the plurality of holes on the first surface of the perforated current collector differs from a mean hole opening area of the plurality of holes on the second surface by at least about 20%. The phrase “mean hole opening area of the plurality of holes”, as used herein, refers to the area of each individual hole, such that at least about 90% of said holes have opening areas on the first surface that differ by at least about 20% from their corresponding opening areas on the second surface.

[0225] In some embodiments, at least about 95% of said holes have opening areas on the first surface that differ by at least about 20% from their corresponding opening areas on the second surface. In certain embodiments, essentially all holes have opening areas on the first surface that differ by at least about 20% from their corresponding opening areas on the second surface.

[0226] In some embodiments, the mean hole opening area of the plurality of holes on the first surface is at least about 20% larger than the mean hole opening area of the plurality of holes on the second surface. In further embodiments, the mean hole opening area of the plurality of holes on the first surface is at least about 25% larger than the mean hole opening area of the plurality of holes on the second surface. In certain embodiments, the mean hole opening area of the plurality of holes on the first surfaceis about 30% larger than the mean hole opening area of the plurality of holes on the second surface.

[0227] FIG. 5 illustrates a top view of a section of perforated current collector 101, according to some embodiments of the present invention. Current collector 101 has first (top) surface 103 and an opposite, second (bottom) surface (hidden from view). Current collector 101 includes hole 105 extending through its entire thickness, with hole opening 105 a on the first surface being larger than hole opening 105b on the second surface.

[0228] In some embodiments, the mean hole opening area on the first surface of the perforated current collector ranges from about 100 pm2to about 1.7 mm2, including each value and sub-range within the specified range. In further embodiments, the mean hole opening area on the first surface ranges from about 300 pm2to about 0.8 mm2. In yet further embodiments, the mean hole opening area on the first surface ranges from about 2,000 pm2to about 0.15 mm2. In still further embodiments, the mean hole opening area on the first surface ranges from about 5,000 pm2to about 30,000 pm2. In certain embodiments, the mean opening area on the first surface is about 13,000 pm2.

[0229] In some embodiments, the mean hole opening area on the second surface of the perforated current collector ranges from about 80 pm2to about 1.3 mm2. In further embodiments, the mean hole opening area on the second surface ranges from about 250 pm2to about 0.65 mm2. In some embodiments, the mean hole opening area on the second surface ranges from about 1,500 pm2to about 0.12 mm2. In further embodiments, the mean hole opening area on the second surface ranges from about 4,000 pm2to about 25,000 pm2. In certain embodiments, the mean opening area is about 10,000 pm2.

[0230] Measuring the hole opening area (instead of the hole opening size, as detailed hereinbelow) is particularly useful when the hole opening has an irregular shape. The area of a plurality of holes may be measured and analyzed by the various methods listed hereinbelow with respect to the measurement of hole diameter and statistical analyses may be applied to calculate mean opening area.

[0231] The hole opening may also be defined by its size (as well as its mean opening size). The term “opening size”, as used herein, refers, in some embodiments, to a value corresponding to a length of the hole in the largest dimension thereof. For example, foran essentially circular hole, the opening size should coincide with its diameter, for a square hole, the hole opening would be the length of its diagonal, and for an oval hole, the opening size would be defined as the length of its major axis. In some embodiments, the term “opening size” refers to a diameter of a circle that encloses an opening defined by its surrounding solid material.

[0232] In some instances, particularly when the hole has a well-defined geometric shape, measuring the characteristic length of the hole can be more convenient and accurate than measuring its area. This approach is especially useful in scenarios where cross-sectional samples are being analyzed, as the hole opening is typically expressed as a linear dimension rather than an area. For example, the diameter of a circular hole or the width of a rectangular or elliptical hole can provide a precise representation of the hole's size. To convert between the length and area of a hole, the specific geometry of the hole must be considered.

[0233] In general, the mean opening size of the plurality of holes of the perforated current collector may range from about 5 pm to about 2000 pm.

[0234] In some embodiments, the mean opening size is less than about 1500 pm, less than about 1000 pm, less than about 500 pm, less than about 250 pm, less than about 200 pm, less than about 150 pm, less than about 130 pm, or less than about 100 pm.

[0235] In some embodiments, the mean opening size is at least about 10 pm, at least about 20 pm, at least about 40 pm, at least about 50 pm, at least about 80 pm, at least about 100 pm, at least about 130 pm, at least about 150 pm, or at least about 200 pm.

[0236] In some embodiments, the mean opening size ranges from about 10 pm to about 1500 pm, or about 20 pm to about 1000 pm, or about 40 pm to about 500 pm, or about 50 pm to about 250 pm, or about 80 pm to about 200 pm, or about 100 pm to about 150 pm.

[0237] The term “opening size” may refer to the hole opening size at the first surface of the current collector, at the second surface of the current collector, or at any point along the thickness of the current collector. According to the principles of the present invention, the hole opening size of the plurality of holes on the first surface and the second surface of the current collector is different. Accordingly, if the position of the hole opening relatively to the current collector thickness is not indicated (e.g., “hole opening on the first surface of the current collector” or “hole opening on the secondsurface of the current collector”), the term “opening size” refers to the smallest diameter of the hole along the current collector thickness, or in other words, the opening size of the hole is measured at the narrowest part of the hole opening. In some embodiments, the narrowest part of the hole opening is on the second surface of the current collector.

[0238] In some embodiments, the mean hole opening size of the plurality of holes on the first surface is at least about 5% larger than the mean hole opening size of the plurality of holes on the second surface. In further embodiments, the mean hole opening size of the plurality of holes on the first surface is at least about 10% larger than the mean hole opening size of the plurality of holes on the second surface. In certain embodiments, the mean hole opening size of the plurality of holes on the first surface is about 15% larger than the mean hole opening size of the plurality of holes on the second surface.

[0239] In some embodiments, the plurality of holes on the first surface have a mean opening size ranging from about 15 pm to about 1500 pm, including each value and sub-range within the specified range. In further embodiments, the mean opening size on the first surface ranges from about 20 pm to about 1000 pm. In still further embodiments, the mean opening size on the first surface ranges from about 50 pm to about 500 pm. In yet further embodiments, the mean opening size on the first surface ranges from about 80 pm to about 200 pm. In certain embodiments, the mean opening size on the first surface is about 130 pm.

[0240] In some embodiments, the plurality of holes on the second surface have a mean opening size ranging from about 12 pm to about 1200 pm, including each value and sub-range within the specified range. In further embodiments, the mean opening size on the first surface ranges from about 15 pm to about 800 pm. 40 pm to about 400 pm. In further embodiments, the mean opening size on the second surface ranges from about 65 pm to about 150 pm. In certain embodiments, the mean opening size on the second surface is about 115 pm.

[0241] The hole opening size of the perforated current collector may be measured using various techniques depending on the precision and hole size, including but not limited to an optical microscope or SEM. Both top view and cross-sectional current collector samples can be analyzed by optical and electron microscopy. Particle Sizing Analysis techniques such as laser diffraction or dynamic light scattering may also be employedto indirectly measure the hole sizes by analyzing the size distribution of particles that pass through the current collector.

[0242] The above techniques allow measuring opening sizes of a plurality of individual holes, and / or an average hole opening size value of a tested number of holes. As the perforated current collector includes a plurality of holes, which sizes may differ (even if only slightly), the term “opening size” as used herein, generally refers to a mean opening size of a plurality of holes of the perforated current collector rather that to an individual hole, unless indicated otherwise. The term ’’mean opening size”, as used herein, refers to the average size of the hole openings in a perforated current collector, which may be measured as part of a size distribution analysis or calculated manually. To determine the mean hole opening, one of the methods mentioned hereinabove, such as optical microscopy, image analysis software, or SEM, can be used to measure the individual sizes of multiple holes across a sample of the perforated material. These measurements are then aggregated to calculate the average size, providing insight into the typical dimension of the holes in the current collector.

[0243] The hole opening size of a plurality of holes may also be measured by taking a picture from the surface side of the perforated current collector foil with a bottom light source of parallel or non-parallel light using an optical microscope or a camera with the suitable resolution, wherein each hole is captured with transmitted light. The entire width of the foil may be analyzed in-situ (during foil manufacturing or electrode coating) or ex-situ by image analysis software to calculate a mean opening size of the plurality of holes within a certain longitudinal section of the current collector or along the entire length thereof.

[0244] The mean opening size of the hole may also provide a quantitative measure of the size distribution of the holes. In some embodiments, the perforated current collector is characterized by narrow opening size distribution. The term “narrow opening size distribution” as used herein refers, in some embodiments, to a distribution wherein more than 90% of the holes of the perforated current collector have an opening size in the range of 0.5- 1.5 times the mean opening size. In certain embodiments, more than 95% of the holes have an opening size within this range. Even more preferably more than 99% of the holes have an opening size within this range. Thus, for a mean opening size of 100 pm, a narrow size distribution may refer to a distribution wherein more than 90%, 95% or 99% of the holes have an opening size in the range of 50-150 pm.In some embodiments, the term “narrow opening size distribution” refers to a distribution wherein more than 90% of the holes of the perforated current collector have an opening size in the range of 0.8- 1.2 times the mean opening size. In certain embodiments, more than 95% of the holes have an opening size within this range. Even more preferably more than 99% of the holes have an opening size within this range.

[0245] Opening size distribution may be defined in terms of the mean particle size and the width of the distribution. The width of the distribution curve at one half of the maximum value is termed full width at half maximum (FWHM). The relationship between the FWHM and mean opening size is used as a measure of broadness or narrowness of the distribution. For example, a distribution having a FWHM value that is larger than the mean opening size is considered relatively broad. As discussed above, the perforated current collectors used in the present invention have a narrow opening size distribution of the plurality of holes. In some embodiments, the term “narrow opening size distribution” refers to a distribution in which the FWHM of the distribution curve is equal to the difference between the mean opening size plus 20% of the mean and the mean opening size minus 40% of the mean. In particular, the FWHM of the distribution curve is equal to two times 20% of the mean, i.e. 40% of the mean. Thus, a narrow opening size distribution may refer to a distribution wherein the FWHM is less than or equal to 40% of the mean opening size. In some embodiments, the FWHM is less than or equal to 20% of the mean opening size. In further embodiments, the FWHM is less than or equal to 10% of the mean opening size.

[0246] The present disclosure pertains to a perforated current collector featuring holes that exhibit a cross-sectional configuration ensuring that the opening area on opposite sides of the current collector differs by at least about 20%. The design and geometry of the holes can vary, provided that this requirement is satisfied, and the holes are capable of contributing to the desired improved adhesion and higher density of the electrode manufactured by a dry coating process.

[0247] The reduction in the hole opening area between the first surface and the second surface may occur in a continuous manner, such as linear tapering or exponential tapering, or follow a non-linear profile. Typically, all the holes taper to the same side of the current collector.For example, the hole may have a tapered profile, where the hole opening on the first surface of the current collector is larger than the hole opening on the second surface. This tapering can be symmetric, such as when the tapering is uniform and centered around the hole's axis, or asymmetric, where the tapering is offset or slanted.

[0248] In some embodiments, the hole may have a straight- sided, slanted profile, wherein the sides of the hole are inclined rather than perpendicular to the surface of the current collector (as illustrated in Figure 6A). The angle of inclination may be at least about 5 degrees relative to a line normal (perpendicular) to the first surface and / or the second surface. In some embodiments, the angle of inclination is at least about 10 degrees. In further embodiments, the angle of inclination is at least about 20 degrees. In still further embodiments, the angle of inclination is at least about 30 degrees. In yet further embodiments, the angle of inclination is at least about 40 degrees.

[0249] Non-linearly tapered hole profiles refer to holes where the reduction in the cross-sectional area or width between the first surface and the second surface does not follow a linear or straight- sided trajectory. Instead, the tapering follows a curved, irregular, or segmented path, resulting in various geometrical shapes that can be tailored for specific functional properties.

[0250] In some embodiments, the holes have an asymmetric non-linear profile. The term “asymmetric non-linear profile", as used herein, refers in some embodiments, to the sides of the hole which taper non- symmetrically across the axis of the hole, resulting in a slanted curvature on one or more sides. The angle of curvature of the hole with an asymmetric non-linear profile may vary across different sections of the hole.

[0251] In some embodiments, the holes have a concave tapered profile (as illustrated in Figure 6B). The term “concave tapered profile”, as used herein, refers in some embodiments, to the sides of the hole which curve inward as they progress from the larger hole opening (e.g., on the first surface of the current collector) to the smaller hole opening (e.g., on the second surface of the current collector), forming a concave shape. The holes with the concave tapered profile may be characterized by a more gradual reduction in area near the larger hole opening and a steeper reduction closer to the smaller hole opening. The profile shape may be described by parabolic, hyperbolic, exponential, logarithmic, or similar mathematical functions.In some embodiments, the holes have a convex tapered profile (as illustrated in Figure 6C). The term “convex tapered profile”, as used herein, refers in some embodiments, to the sides of the hole which curve outward as they progress from the larger hole opening (e.g., on the first surface of the current collector) to the smaller hole opening (e.g., on the second surface of the current collector), forming a convex shape. The holes with the convex tapered profile may characterized by a steeper reduction in area near the larger hole opening and a steeper reduction closer to the smaller hole opening. The profile shape may be described by parabolic, hyperbolic, exponential, logarithmic, or similar mathematical functions.

[0252] In some embodiments, the holes have a compound curved profile. The term “compound curved profile”, as used herein, refers in some embodiments, to the sides of the hole which tapering follows a compound curvature, such as an S-shaped path, with alternating concave and convex regions. The holes having a compound curved profile may provide a complex transition between the first and the second surface of the current collector.

[0253] In some embodiments, the holes have a stepped or segmented profile (as illustrated in Figure 6D). The terms “stepped profile” and “segmented profile”, which may be used herein interchangeably, refer to the sides of the hole which taper in discrete steps rather than a smooth curve, creating a segmented profile with multiple levels of hole diameter reduction. For example, each step may have a flat section followed by a steep transition to the next smaller section.

[0254] According to some embodiments, the holes have a complex profile comprising two or more of the above features (e.g., a generally stepped profile, wherein one or more of the steps may be described by parabolic, hyperbolic, exponential, logarithmic, or similar mathematical functions).

[0255] In some embodiments, the holes have an irregular non-linear profile. The term “irregular non-linear profile”, as used herein, refer in some embodiments, to the sides of the hole which tapering does not follow a predictable mathematical function, resulting in irregularly- shaped profiles.

[0256] The particular hole profile design may be chosen to enable optimization for mechanical, fluidic, or functional requirements of the perforated current collector, aslong as the hole opening on the first surface and the second surface differ, in accordance with the principles of the present invention.

[0257] Another metric which may describe the perforation pattern of the current collector is hole density. Depending on the distance between adjacent holes and the arrangement of the holes along and across the current collector plane, the mean hole size may be translated into hole density. In the context of the present invention, the hole density of a current collector relates to the number of through-holes per unit area. In some embodiments, the hole density relates to the ratio between the solid (e.g., metal) area and hole opening area of the plurality of holes per unit area.

[0258] The hole density may range from about 0.1 holes per 1 mm2(square millimeter) to about 5,000 holes / mm2, including each value and sub-range within the specified range. According to some embodiments, the hole density ranges from about 0.5 holes / mm2to about 1,500 holes / mm2, from about 2.5 holes / mm2to about 250 holes / mm2, from about 15 holes / mm2to about 200 holes / mm2, from about 20 holes / mm2to about 100 holes / mm2, or from about 30 holes / mm2to about 60 holes / mm2.

[0259] The hole density is also correlated with the distance between adjacent holes, or, in other words, the width of the solid material between the holes. In some embodiments, the distance between the centers of two adjacent holes (also termed herein “pitch”) ranges about 15-2000 pm, about 20-1000 pm, 30-500 pm, 50-400 pm, 75-300, 100-250 pm, 100-1000 pm, 250-350 pm, 300-400 pm, or 600-700 pm. Each possibility represents a separate embodiment of the invention.

[0260] The term “pitch”, as used herein with respect to the holes distance, refers to the shortest distance between the centers of two adjacent holes along the longitudinal axis of the current collector.

[0261] The hole pitch may be at least 5% larger than the mean hole size. In some embodiments, the hole pitch is at least 10% larger than the mean hole size. In further embodiments, the hole pitch is at least 20% larger than the mean hole size. In yet further embodiments, the hole pitch is at least 30% larger than the mean hole size. In still further embodiments, the hole pitch is at least 40% larger than the mean hole size. In yet further embodiments, the hole pitch is at least 50% larger than the mean hole size. In additional embodiments, the hole pitch is at least 75% larger than the mean hole size. In certain embodiments, the hole pitch is at least 100% larger than the mean hole size.Perforation pattern of the current collector may further be characterized by the relative position of the holes. For example, if the holes are staggered, the perforation pattern may be characterized by a stagger angle, that may range from about 20° to about 160°. The term “stagger angle”, as used herein, refers to an angle formed between two straight lines that connect the center of a hole with the centres of holes adjacent thereto (that are not positioned along the same longitudinal or transverse axis of the current collector). In some embodiments, the stagger angle ranges from about 40° to about 90°. In further embodiments, the stagger angle ranges from about 50° to about 75°. In some embodiments, the stagger angle is about 60°.

[0262] The perforation pattern of the current collector may further be defined by an open area, i.e., a total area that the holes occupy relatively to the total geometrical area of the current collector plane. The open area of the current collector may range from about 1% to about 60%. In some embodiments, the open area of the current collector ranges from about 5% to about 50%, from about 10% to about 40%, or from about 15% to about 30%. Unless indicated otherwise, the open area refers to the total area of the holes on the current collector surface with the smaller hole openings.

[0263] The open area of the perforated current collector may be assessed by imaging a certain area of the perforated current collector by image analysis software, as described hereinabove with respect to measuring hole opening size, and calculating a ratio of the total opening area of the through-holes to an area of the imaged geometric area. Similarly, a hole density may be assessed by calculating the number of holes within said certain area and diving said number by the imaged geometric area. These operations may be performed in multiple locations (such as 2, 3, 5, 10 or more locations) by changing the observation position, and an average of the open area and of the hole density may be obtained.

[0264] Perforated current collector

[0265] The perforation pattern of the current collector, which can be applied to any of the embodiments described herein, may be further characterized by the following general features

[0266] According to some embodiments, the perforated current collector has a first surface and a second (opposite) surface. A shortest distance between the first surfaceand the second surface may be referred to as a local thickness of the perforated current collector. In further embodiments, the second surface is essentially parallel to the first surface. In yet further embodiments, the first surface conforms to the first surface.

[0267] The perforated current collector may have a local thickness ranging from about 2 pm to about 100 pm. In some embodiments, the local thickness ranges from about 3 pm to about 50 pm. In certain embodiments, the local thickness ranges from about 4 pm to about 30 pm. In further embodiments, the local thickness ranges from about 5 pm to about 20 pm.

[0268] The perforation and embossing patterns of the current collector may be aligned or misaligned.

[0269] The perforation pattern may be non-random. In some embodiments, the current collector is purposely designed to have regularly spaced and oriented holes. The perforated current collector may be further characterized by a seamless repeating pattern of through holes spanning the majority of or the entire area of the current collector without visible boundaries or irregular / arbitrary / random transitions between the repeating pattern motifs or within the motifs.

[0270] Practically, in some embodiments, the perforated current collector exhibits the seamless repeating perforation pattern over the entire area thereof, from edge to edge; in some embodiments, the SRP spans the major area of the current collector, leaving narrow margins along its edges due to technical / practical requirements of industrial processing machinery or battery application (e.g., tab welding). By margins, it is meant that the current collector does not exhibit the SRP in the area regarded as the margins, wherein the foil can be unperforated or have a different perforation pattern than the SRP. The margin may further include a combination of unperforated area and an area having a different perforation pattern than the SRP. In some embodiments, the margins extend on each edge of the metal foil, and in some embodiments, wherein the foil is a long sheet being more than 10-times longer than wide, the margins span less than 1 %, less than 2 %, less than 5 %, less than 10 %, less than 15%, or less than 20 % of the total width of the current collector.

[0271] The seamless repeating perforation pattern, according to some embodiments of the present invention, is mathematically defined or constructed. In some embodiments, the seamless repeating perforation pattern is generated by machine learning to producea desired battery capability (such as, but not limited to, high-capacity retention, inter alia, due to better active material adhesion, or high energy density).

[0272] The uniformity of the SRP of the perforation pattern may be determined by any experimental method, such as, for example, taking optical or microscopy images of different sections of the member, scanning a pre-determined area within the image or different images, identifying and digitizing the motifs in the scanned image and measuring the size and horizontal distance of a predetermined number of motifs per scanned section, and calculating the standard deviation in motif over across sections. In some embodiments, the standard deviation in motif overlap ranges 0-15 %. In some embodiments, the standard deviation in motif overlap is less than 15 %, less than 10 %, or less than 5 %.

[0273] The mean opening size of the plurality of holes of the perforated current collector may be selected based on whether the current collector is designated for an anode or a cathode, on the type and properties of the electrode composition, and on the desired battery characteristics. In general, the mean opening size may range from about 5 pm to about 2000 pm.

[0274] In some embodiments, the mean opening size is less than about 1500 pm, less than about 1000 pm, less than about 500 pm, less than about 250 pm, less than about 200 pm, less than about 150 pm, less than about 130 pm, or less than about 100 pm.

[0275] In some embodiments, the mean opening size is at least about 10 pm, at least about 20 pm, at least about 40 pm, at least about 50 pm, at least about 80 pm, at least about 100 pm, at least about 130 pm, at least about 150 pm, or at least about 200 pm.

[0276] In some embodiments, the mean opening size ranges from about 10 pm to about 1500 pm, or about 20 pm to about 1000 pm, or about 40 pm to about 500 pm, or about 50 pm to about 250 pm, or about 80 pm to about 200 pm, or about 100 pm to about 150 pm.

[0277] In some embodiments, the mean opening size ranges from about 10 pm to about 30 pm, or about 30 pm to about 50 pm, or about 50 pm to about 70 pm, or about 70 pm to about 100 pm, or about 100 pm to about 150 pm, or about 150 pm to about 250 pm, or about 250 pm to about 500 pm, or about 500 pm to about 750 pm, or about 750 pm to about 1000 pm, or about 1000 pm to about 2000 pm.The term “opening size”, as used herein, refers, in some embodiments, to a value corresponding to a length of the hole in the largest dimension thereof. For example, for an essentially circular hole, the opening size should coincide with its diameter, for a square hole, the hole opening would be the length of its diagonal, and for an oval hole, the opening size would be defined as the length of its major axis. In some embodiments, the term “opening size” refers to a diameter of a circle that encloses an opening defined by its surrounding solid material.

[0278] As the current collector has a defined local thickness, the holes have an opening on the first surface of the current collector and on the second surface of the current collector. The term “opening size” may refer to the hole opening size at the first surface of the current collector, at the second surface of the current collector, or at any point along the thickness of the current collector. When the hole walls are parallel (e.g., when the hole is cylindrical or cuboid), the hole opening size is constant along the current collector thickness, and the term “opening size” may refer to an opening at any point along the current collector thickness. If the hole walls are not parallel and the position of the hole opening relatively to the current collector thickness is not indicated (e.g., “hole opening on the first surface of the current collector” or “hole opening on the second surface of the current collector”), the term “opening size” refers to the smallest diameter of the hole along the current collector thickness. For example, if the hole has a tapered or hourglass profile, the opening size of the hole is measured at the narrowest part of the hole opening (i.e., the narrowest part along the current collector thickness).

[0279] The hole opening size of the perforated current collector may be measured using various techniques depending on the precision and hole size, including but not limited to an optical microscope or SEM. Both top view and cross-sectional current collector samples can be analyzed by optical and electron microscopy. Particle Sizing Analysis techniques such as laser diffraction or dynamic light scattering may also be employed to indirectly measure the hole sizes by analyzing the size distribution of particles that pass through the current collector.

[0280] In some embodiments, the opening size is measured using two-dimensional X-ray imaging, wherein the perforated current collector is imaged using X-ray transmission to resolve the openings through the thickness of the foil without physical sectioning.The above techniques allow measuring opening sizes of a plurality of individual holes, and / or an average hole opening size value of a tested number of holes. As the perforated current collector includes a plurality of holes, which sizes may differ (even if only slightly), the term “opening size” as used herein, generally refers to a mean opening size of a plurality of holes of the perforated current collector rather that to an individual hole, unless indicated otherwise. The term "mean opening size”, as used herein, refers to the average size of the hole openings in a perforated current collector, which may be measured as part of a size distribution analysis or calculated manually. To determine the mean hole opening, one of the methods mentioned hereinabove, such as optical microscopy, image analysis software, or SEM, can be used to measure the individual sizes of multiple holes across a sample of the perforated material. These measurements are then aggregated to calculate the average size, providing insight into the typical dimension of the holes in the current collector.

[0281] The hole opening size of a plurality of holes may also be measured by taking a picture from the surface side of the perforated current collector foil with a bottom light source of parallel or non-parallel light using an optical microscope or a camera with the suitable resolution, wherein each hole is captured with transmitted light. The entire width of the foil may be analyzed in-situ (during foil manufacturing or electrode coating) or ex-situ by image analysis software to calculate a mean opening size of the plurality of holes within a certain longitudinal section of the current collector or along the entire length thereof.

[0282] The mean opening size of the hole may also provide a quantitative measure of the size distribution of the holes. In some embodiments, the perforated current collector is characterized by narrow opening size distribution. The term “narrow opening size distribution” as used herein refers, in some embodiments, to a distribution wherein more than 90% of the holes of the perforated current collector have an opening size in the range of 0.5- 1.5 times the mean opening size. In certain embodiments, more than 95% of the holes have an opening size within this range. Even more preferably more than 99% of the holes have an opening size within this range. Thus, for a mean opening size of 100 pm, a narrow size distribution may refer to a distribution wherein more than 90%, 95% or 99% of the holes have an opening size in the range of 50-150 pm.

[0283] In some embodiments, the term “narrow opening size distribution” refers to a distribution wherein more than 90% of the holes of the perforated current collector havean opening size in the range of 0.8- 1.2 times the mean opening size. In certain embodiments, more than 95% of the holes have an opening size within this range. Even more preferably more than 99% of the holes have an opening size within this range.

[0284] Opening size distribution may be defined in terms of the mean particle size and the width of the distribution. The width of the distribution curve at one half of the maximum value is termed full width at half maximum (FWHM). The relationship between the FWHM and mean opening size is used as a measure of broadness or narrowness of the distribution. For example, a distribution having a FWHM value that is larger than the mean opening size is considered relatively broad. As discussed above, the perforated current collectors used in the present invention have a narrow opening size distribution of the plurality of holes. In some embodiments, the term “narrow opening size distribution” refers to a distribution in which the FWHM of the distribution curve is equal to the difference between the mean opening size plus 20% of the mean and the mean opening size minus 40% of the mean. In particular, the FWHM of the distribution curve is equal to two times 20% of the mean, i.e. 40% of the mean. Thus, a narrow opening size distribution may refer to a distribution wherein the FWHM is less than or equal to 40% of the mean opening size. In some embodiments, the FWHM is less than or equal to 20% of the mean opening size. In further embodiments, the FWHM is less than or equal to 10% of the mean opening size.

[0285] An area of the hole opening (as well as a mean opening area), may also be used to define hole opening size. In some instances, for example when the hole has an irregular shape, it may be easier and / or more accurate to measure the area of the hole instead of its length. The area of a plurality of holes may be measured and analyzed by the various methods listed hereinabove with respect to the measurement of hole diameter and statistical analyses may be applied to calculate mean opening area. In some embodiments, the mean opening area may range from about 20 pm2to about 3 2

[0286] mm .

[0287] In some embodiments, the mean hole opening area is less than about 1.7 mm2, less than about 0.8 mm2, less than about 0.2 mm2, less than about 50,000 pm2, less than about 30,000 pm2, less than about 18,000 pm2, less than about 13,000 pm2, or less than about 8,000 pm2. Each possibility represents a separate embodiment of the invention.In some embodiments, the mean hole opening area is at least about 80 pm2, at least about 300 pm2, at least about 1,200 pm2, at least about 2,000 pm2, at least about 5,000 pm2, at least about 7,500 pm2, at least about 13,000 pm2, at least about 18,000 pm2, or at least about 30,000 pm2. Each possibility represents a separate embodiment of the invention.

[0288] In some embodiments, the mean hole opening area ranges from about 80 pm2to about 1.7 mm2, or about 300 pm2to about 0.8 mm2, or about 1,200 pm2to about 0.2 mm2, or about 2,000 pm2to about 50,000 pm2, or about 5,000 pm2to about 30,000 pm2, or about 7,500 pm2to about 18,000 pm2. Each possibility represents a separate embodiment of the invention

[0289] In some embodiments, the mean opening area ranges from about 100 pm2to about 700 pm2, or about 700 pm2to about 2,000 pm2, or about 2,000 pm2to about 4,000 pm2, or about 4,000 pm2to about 8,000 pm2, or about 8,000 pm2to about 18,000 pm2, or about 18,000 pm2to about 50,000 pm2, or about 50,000 pm2to about 200,000 pm2, or about 200,000 pm2to about 450,000 pm2, or about 450,000 pm2to about 800,000 pm2, or about 800,000 pm2to about 3,000,000 pm2.

[0290] Another metric which may describe the perforation pattern of the current collector is hole density. Depending on the distance between adjacent holes and the arrangement of the holes along and across the current collector plane, the mean hole size may be translated into hole density. In the context of the present invention, the hole density of a current collector relates to the number of through-holes per unit area. In some embodiments, the hole density relates to the ratio between the solid (e.g., metal) area and hole opening area of the plurality of holes per unit area.

[0291] The hole density may range from about 0.1 holes per 1 mm2(square millimeter) to about 5,000 holes / mm2. According to some embodiments, the hole density ranges from about 0.5 holes / mm2to about 1,500 holes / mm2, from about 2.5 holes / mm2to about 250 holes / mm2, from about 15 holes / mm2to about 200 holes / mm2, from about 20 holes / mm2to about 100 holes / mm2, or from about 30 holes / mm2to about 60 holes / mm2. Each possibility represents a separate embodiment of the invention.

[0292] The hole density is also correlated with the distance between adjacent holes, or, in other words, the width of the solid material between the holes. In some embodiments, the distance between the centers of two adjacent holes (also termed herein “pitch”)ranges about 15-2000 |am, or about 20-1000 |am, or 30-500 |am, 50-400 |am, 75-300, 100-250 |am, 100-1000 |am, 250-350 |am, 300-400 |am, or 600-700 |am.

[0293] The term “pitch”, as used herein with respect to the holes distance, refers to the shortest distance between the centers of two adjacent holes along the longitudinal axis of the current collector.

[0294] The hole pitch may be at least 5% larger than the mean hole size. In some embodiments, the hole pitch is at least 10% larger than the mean hole size. In further embodiments, the hole pitch is at least 20% larger than the mean hole size. In yet further embodiments, the hole pitch is at least 30% larger than the mean hole size. In still further embodiments, the hole pitch is at least 40% larger than the mean hole size. In yet further embodiments, the hole pitch is at least 50% larger than the mean hole size. In additional embodiments, the hole pitch is at least 75% larger than the mean hole size. In certain embodiments, the hole pitch is at least 100% larger than the mean hole size.

[0295] Perforation pattern of the current collector may further be characterized by the relative position of the holes. For example, if the holes are staggered, the perforation pattern may be characterized by a stagger angle, that may range from about 20° to about 160°. The term “stagger angle”, as used herein, refers to an angle formed between two straight lines that connect the center of a hole with the centers of holes adjacent thereto (that are not positioned along the same longitudinal or transverse axis of the current collector). In some embodiments, the stagger angle ranges from about 40° to about 90°. In further embodiments, the stagger angle ranges from about 50° to about 75°. In some embodiments, the stagger angle is about 60°.

[0296] The perforation pattern of the current collector may further be defined by an open area, i.e., a total area that the holes occupy relatively to the total geometrical area of the current collector plane. The open area of the current collector may range from about 1% to about 60%. In some embodiments, the open area of the current collector ranges from about 3% to about 55%, from about 5% to about 50%, from about 10% to about 40%, or from about 15% to about 30%.

[0297] In some embodiments, the open area of the current collector ranges from about 3% to about 6%, from about 6% to about 10%, from about 10% to about 15%, from about 15% to about 20%, from about 20% to about 25%, from about 25% to about 30%,from about 30% to about 35%, from about 35% to about 40%, or from about 40% to about 60%.

[0298] The open area of the perforated current collector may be assessed by imaging a certain area of the perforated current collector by image analysis software, as described hereinabove with respect to measuring hole opening size, and calculating a ratio of the total opening area of the through-holes to an area of the imaged geometric area. Similarly, a hole density may be assessed by calculating the number of holes within said certain and diving said number by the imaged geometric area. These operations may be performed in multiple locations (such as 2, 3, 5, 10 or more locations) by changing the observation position, and an average of the open area and of the hole density may be obtained.

[0299] Properties of the current collector

[0300] The perforated current collector may have a tensile strength of at least about 150 MPa. In some embodiments, the perforated current collector has a tensile strength of at least about 200 MPa. In further embodiments, the perforated current collector has a tensile strength of at least about 250 MPa. In yet further embodiments, the perforated current collector has a tensile strength of at least about 300 MPa.

[0301] The perforated current collector may further have an elongation of at least about 2%. In some embodiments, the perforated current collector has an elongation of at least about 3%. In further embodiments, the perforated current collector has an elongation of at least about 4%. In yet further embodiments, the perforated current collector has an elongation of at least about 5%.

[0302] The perforated current collector may me composed of any metal that is suitable for use in energy storage and / or generation devices, such as, but not limited to, aluminum, copper, nickel, stainless steel, silver, zinc, tin, iron, titanium, and any combination or alloy thereof. In some embodiments, the metal is aluminum. In some embodiments, the metal is copper.

[0303] Dry coating process

[0304] The terms “dry coating” and “dry coating process”, as used herein, refer to a process for battery electrode manufacturing that involves applying an electrode composition containing an electrode active material, and, optionally, a binder and / orelectrically conductive additive to a current collector, wherein the electrode composition is essentially free of a solvent.

[0305] The term “essentially free”, as used herein in connection to the solvent content, is meant to encompass an electrode composition containing less than about 10 wt% solvent based on the total weight of the electrode composition. In some embodiments, the first electrode composition contains less than about 5 wt% solvent. In further embodiments, the first electrode composition contains less than about 1 wt% solvent. In yet further embodiments, the first electrode composition contains less than about 0.1 wt% solvent. In some embodiments, the second electrode composition contains less than about 5 wt% solvent. In further embodiments, the second electrode composition contains less than about 1 wt% solvent. In yet further embodiments, the second electrode composition contains less than about 0.1 wt% solvent.

[0306] According to the principles of the present invention, the first electrode composition is applied to at least a first surface of a perforated current collector, wherein at least a portion of the plurality of holes of the perforated current collector have an inner wall surface that forms a non-right angle with the longitudinal plane of the current collector. Typically, the electrode composition is applied in parallel to the longitudinal plane of the current collector. Thus, in the disclosed perforated current collector in which at least a portion of the plurality of holes have an inner wall surface that forms a non-right angle with the longitudinal plane of the current collector, said portion of the plurality of holes would have a hole wall surface that is not perpendicular to the electrode composition applied thereto. Compared to a current collector in which the hole walls are perpendicular to the applied electrode composition, the disclosed design may enable enhanced material penetration and packing efficiency.

[0307] Reference is now made to Figure 2A, which schematically illustrates a crosssection of electrode 201, during dry coating manufacturing process. Electrode 201 includes perforated current collector 203 having a flat surface to which electrode composition 205 is applied. Electrode composition 205 is provided in Figure 2A as a film. Perforated current collector 203 has multiple holes, represented by hole 207, hole opening plane J of hole 207 being aligned in parallel to longitudinal plane I of electrode composition 205. Hole walls are aligned perpendicularly (as represented by line K and angle L of 90°) to longitudinal plane I. Due to the flat surface of current collector 203, applied electrode composition enters hole 207 with a length equal to the hole openingsize, as electrode composition 205 comes into contact with the hole walls at a right angle.

[0308] Reference is now made to Figure 2B, which schematically illustrates a crosssection of electrode 301 during a dry coating manufacturing process, according to some embodiments of the present invention. Electrode 301 includes perforated current collector 303, which has a non-flat surface to which electrode composition 305 (in the form of a film) is being applied. Perforated current collector 303 has multiple holes, represented by hole 307, where hole opening plane J of hole 307 is tilted at an angle relative to longitudinal plane I of electrode composition 305 due to the non-flat nature of the current collector. The hole walls are aligned at an angle different from 90° (as represented by line K and angle L) relative to longitudinal plane I. Due to the tilted surface of current collector 303, applied electrode composition 305 enters hole 307 with a length that is greater than the hole opening size, as electrode composition 305 comes into contact with the hole walls at an angle that extends the path length. This configuration results in a longer path of electrode material within hole 307, potentially allowing for a denser packing of active material, which may improve the electrical conductivity and mechanical adhesion within the electrode.

[0309] In some embodiments, the first electrode composition is applied to the surface of the current collector in the form of a solid film. In some embodiments, the second electrode composition is applied to the surface of the current collector in the form of a solid film. The angle between the inner wall surface of the holes and the longitudinal plane of such film may range from about 0° to about 85° or from about 95° to about 180°. In some embodiments, the angle ranges from about 10° to about 90°, from about 20° to about 80°, from about 30° to about 70°, from about 40° to about 60°, from about 5° to about 50°, from about 10° to about 30°, from about 130° to about 175°, or from about 150° to about 170°. Each possibility represents a separate embodiment of the invention.

[0310] The first electrode composition may be applied to at least the first surface of the perforated current collector to be in a direct contact with said first surface. It is to be emphasized that the use of the perforated current collector having the tilted hole walls orientation obviates the need for use of adhesion promoters (such as, e.g., thermoplastic polymers and their mixtures with conductive additives), which are typically applied between the current collector and the electrode composition in dry coating processes.Electrode composition

[0311] As mentioned hereinabove, the electrode composition includes an electrode active material. The electrode active material may be selected based on the desired properties of the energy storage and / or generation device in which it is included.

[0312] The term "electrode active material", as used herein, refers to a substance within an electrochemical energy storage and / or generation device capable of either generating or receiving electrons, undergoing oxidation or reduction, or reversibly binding and releasing charge carrier species. In this context, "anode active material" denotes an electrode active material associated with an anode, while "cathode active material" refers to an electrode active material associated with a cathode.

[0313] Electrode active materials suitable for use in the electrode compositions of the present invention may be selected from, but not limited to, graphite, amorphous carbon, mesoporous carbon, graphene, silicon oxide (silicon suboxide), silicon dioxide, carbon-modified silicon-based materials, niobium titanium oxide, tin, antimony, bismuth, lead, cobalt oxide, iron oxide, tin oxide, manganese oxide, molybdenum sulfide, tungstem sulfide, tin phosphide, sodium vanadium phosphate, sodium terephthalate, sodium rhodizonate, lithium nickel manganese cobalt oxide, lithium iron phosphate, lithium iron manganese phosphate, lithium nickel manganese oxide, lithium cobalt oxide, lithium nickel cobalt aluminum oxide, lithium cobalt aluminum oxide, lithium titanium oxide, mixed niobium oxide, sulfur, lithium sulfide, iron fluoride, copper fluoride, sodium nickel oxide, sodium cobalt oxide, sodium iron oxide, sodium chromium oxide, sodium manganese oxide, sodium vanadium phosphate, sodium iron phosphate, sodium manganese phosphate, sodium iron pyrophosphate, sodium iron sulfide, zinc, NaVPCUF, Na3V2(PO4)2F3, Na2Fe(CN)6, Nai.32Mn[Fe(CN)6]o.83, Na2CoFe(CN)6, Na4Fe3(PO4)2(P2O?), and combinations thereof. Each possibility represents a separate embodiment of the invention.

[0314] In some embodiments, the electrode active material is suitable for use in a lithium-ion battery. Electrode active materials commonly employed in lithium-ion batteries can be categorized into two types: materials having a relatively high lithium chemical potential and thus being suitable for use as an anode and materials with a relatively low lithium chemical potential, which are suitable for use in cathodes. During discharge, anode materials undergo electrochemical oxidation, releasing electrons to anexternal circuit and lithium ions into the electrolyte, while cathode materials undergo electrochemical reduction by lithium ions from the electrolyte and receiving electrodes from an external circuit.

[0315] Both anode and cathode materials may belong to the class of intercalation materials, such as layered materials capable of hosting lithium ions between layers. Here, "intercalation material" refers to a substance capable of reversibly intercalating and deintercalating one or more chemical species, including alkali metals and / or alkali metal ions.

[0316] While the method according to the principles of the present invention is suitable for use in various types of electrochemical energy storage and / or generation devices, for the purpose of clarity and conciseness, the following sections will focus mostly on lithium-ion batteries.

[0317] Cathode intercalation materials in lithium-ion batteries typically comprise lithium transition metal oxides of the rock salt type, offering high energy density, such as, but not limited to, LiCoCL, or polyanionic materials with high rate capability, such as, but not limited to, LiFcPCU.

[0318] Lithium cobalt oxide is renowned for its high specific capacity and cycling stability. LiCoCL undergoes reversible lithium intercalation and deintercalation processes during charge and discharge cycles, enabling efficient energy storage and retrieval. The crystalline structure of LiCoCh provides a stable framework for lithium ions, ensuring long-term cycling stability and minimal capacity fade.

[0319] Some of the advantages of lithium iron phosphate include its high structural stability, safety, and abundance of raw materials. LiFcPCL operates via a conversion reaction mechanism, wherein lithium ions are inserted and extracted from the crystal lattice during charge and discharge processes. This results in excellent cycling performance and thermal stability, making LiFcPCL a preferred choice for applications demanding high safety standards.

[0320] Anode intercalation materials in lithium-ion batteries typically comprise carbon-based materials. For example, graphite is a commonly employed anode material in LIBs due to its exceptional electrochemical properties, including high lithium intercalation capacity and cycling stability. Graphite comprises carbon atoms arranged in parallel graphene layers, enabling the intercalation of lithium between these layers.Graphite suitable for use in the electrode of the present invention may be synthetic or natural.

[0321] The electrode active material may further be a lithium alloying material. The term "lithium alloying material", as used herein refers to one or more elements that form an alloy or an intermetallic compound with lithium. Non-limiting examples of lithium alloying materials include silicon or silicon oxide, tin, lead, zinc, magnesium, sodium, aluminum, gallium, indium, germanium, alloys, and combinations thereof.

[0322] Silicon-based anode materials, such as silicon, silicon oxide, or silicon alloy, offer substantially higher theoretical specific capacities compared to graphite. The term "silicon oxide", as used herein, refers to a compound of formula SiOx, where 0 < x < 2, encompassing compounds including Si and SiCh, a mixture of one or more compounds of formula SiOx, thereby having an average composition represented by formula SiOx. Silicon and silicon oxide exhibit a high lithium storage capacity through alloying reactions, wherein lithium ions are reversibly incorporated into the silicon lattice during charging and released during discharging. The silicon-based anode material may be combined with graphite or carbonaceous materials to enhance its mechanical stability and electrochemical performance. The silicon-based anode material may further be nanostructured.

[0323] Tin-based materials can also be employed as anode materials for LIBs, offering high lithium storage capacities and improved cycling stability. Tin undergoes alloying reactions with lithium ions, forming lithium-tin alloys with tunable compositions and electrochemical properties.

[0324] In some embodiments, the electrode active material is a cathode active material selected from cobalt oxide, iron oxide, lithium nickel manganese cobalt oxide, lithium iron phosphate, lithium iron manganese phosphate, lithium nickel manganese oxide, lithium cobalt oxide, lithium nickel cobalt aluminum oxide, lithium cobalt aluminum oxide, sulfur, lithium sulfide, iron fluoride, and copper fluoride. In some embodiments, the electrode active material includes lithium nickel manganese cobalt oxide. In some embodiments, the active material is NMC 622. In some embodiments, the active material is NMC 811. In some embodiments, lithium nickel manganese cobalt oxide has a nickel content of at least about 80 at% based on the total weight of nickelmanganese cobalt. In some related embodiments, the perforated current collector is made of aluminum.

[0325] In some embodiments, the electrode active material is an anode active material selected from graphite, amorphous carbon, mesoporous carbon, silicon, silica, carbon-modified silicon-based materials, tin, antimony, cobalt, lithium titanium oxide, and mixed niobium oxide. In certain embodiments, the electrode contains graphite as an electrode active material. In further embodiments, the graphite is an artificial graphite. In some related embodiments, the perforated current collector is made of copper.

[0326] The electrode active material may be present in the first electrode composition in a weight percent ranging from about 90 wt% to about 100 wt%, based of the total weight of the first electrode composition. According to some embodiments, the electrode active material is present in the first electrode composition at a weight percentage ranging from about 90 to 99.5, or from about 93 to about 99, or from about 92 to about 98, or from about 94 to about 96, or from about 97 to about 99, based on the total weight of the first electrode composition. The electrode active material may be present in the second electrode composition in a weight percent ranging from about 90 wt% to about 100 wt%, based of the total weight of the second electrode composition. According to some embodiments, the electrode active material is present in the second electrode composition at a weight percentage ranging from about 90 to 99.5, or from about 93 to about 99, or from about 92 to about 98, or from about 94 to about 96, or from about 97 to about 99, based on the total weight of the second electrode composition.

[0327] In some embodiments, the electrode active material is a cathode active material, which is present in the electrode at a weight percentage ranging from about 90 to 99.5, or from about 92 to about 98, or from about 94 to about 96, based on the total weight of the electrode.

[0328] In some embodiments, the electrode active material is an anode active material, which is present in the electrode at a weight percentage ranging from about 90 to 99.5, or from about 93 to about 99, or from about 97 to about 99, based on the total weight of the first electrode composition. Each possibility represents a separate embodiment of the invention. In some embodiments, the electrode active material is an anode active material, which is present in the electrode at a weight percentage ranging from about90 to 99.5, or from about 93 to about 99, or from about 97 to about 99, based on the total weight of the second electrode composition. Each possibility represents a separate embodiment of the invention.

[0329] Generally, the electrode active material is in granular form. The particles of the electrode active material may assume any shape known in the art, such as, but not limited to, spheres, substantially spherical shapes, polyhedrons, ellipsoids, plates, needles, rods, wires, ribbons, or cylinders. The average particle size of the electrode active material may range from tens of nanometers to hundreds of micrometers, for example, from about 50 nm to about 500 pm, as measured for instance, using a particle size analyzer such as Malvern's Mastersizer 3000.

[0330] In addition to the electrode active material, the electrode composition may additionally include one or more electrode additives aimed at further enhancing the electrode's performance and the efficacy of devices containing such electrodes. The proportion of the electrode additive, whether by weight or volume, may be determined based on the intended application of the energy storage and / or generation device, and a method of electrode manufacturing.

[0331] For example, the electrode composition may include a binder, such as a polymer adhesive binder, which is configured to hold the electrode active material particles together within the electrodes, thereby ensuring structural integrity and enhancing the battery's overall performance. In dry coating processes, the binder is used in its dry form, and may be processed to form a cohesive structure in the absence of solvents. The type of the binder may be selected based on their activation characteristics, either by mechanical pressure or low-temperature heat. Non-limiting examples of binders suitable for use in the electrode composition according to the various embodiments of the present invention include polytetrafluoroethylene (PTFE), poly vinylidene fluoride (PVDF), cellulose, such as, e.g., sodium carboxymethyl cellulose (CMC), and any combination and derivative thereof.

[0332] The term “derivative”, as used herein, refers to a compound that is derived from a similar compound through a chemical modification, inter alia, by replacing one or more atoms, groups of atoms, or functional groups in the original molecule with different atoms or groups while retaining the core structure of the original compound.

[0333] In certain embodiments, the binder is PTFE.The binder may be present in the electrode composition in a weight percent ranging from about 1 wt% to about 5 wt%, based on the total weight of the electrode composition According to some embodiments, the binder is present in the electrode composition at a weight percentage ranging from about 0.5 to 2, or from about 1 to about 3. In certain embodiments, the binder is present in the electrode composition in a weight percent of 2 wt% or less.

[0334] The binder may be present in the electrode composition in a fibrilized form. Such fibrilized binder may form a homogeneous network structure, enhancing the mechanical integrity of the electrode

[0335] Additionally or alternatively, the binder may be present in a particulate form. In some embodiments, the binder comprises particles having a mean particle size below about 50 pm. In further embodiments, the binder comprises particles having a mean particle size below about 40 pm. In yet further embodiments, the binder comprises particles having a mean particle size below about 30 pm. In still further embodiments, the binder comprises particles having a mean particle size below about 20 pm.

[0336] In the context of a lithium-ion battery, the electrode should facilitate the flow of both lithium ions and electrons. To establish a conductive percolation network, a conductive additive may be introduced to the electrode composition. This addition serves to diminish impedance-related energy and power losses within the battery and enables quicker charge and discharge cycles. The electrical characteristics of the electrode can vary based on the mixing ratio of the electrode active material and the conductive additive.

[0337] The conductive additive may be selected from electron-conductive materials, ion-conductive materials, or combinations thereof. Examples of electron-conductive materials include carbonaceous materials like carbon, conductive graphite, graphene, reduced graphene oxide, fullerenes, carbon nanotubes, and carbon fibers. In some embodiments, the electrode contains one or more electron-conductive materials in the form of fine particles, such as nanoscale particles, to establish a percolating network and enhance electrode conductivity. Non-limiting examples of suitable types of carbons include carbon black, acetylene black, and Ketjen black.

[0338] The electron-conductive material may be present in the electrode composition in a weight percent ranging from about 1% to about 10% wt., based on the total weightof the electrode composition. According to some embodiments, the electron-conductive material may be present in the electrode composition at a weight percentage ranging from about 2 to 8, or from about 3 to about 5. In some embodiments, the electrode composition is essentially free of a conductive additive

[0339] In some embodiments, the electrode is a cathode and the electrode composition includes about 94 to about 96 weight percent electrode active material, about 0.5 to about 2 weight percent binder, and about 3 to about 5 weight percent conductive additive.

[0340] In some embodiments, the electrode is an anode and the electrode composition includes about 97 to about 99 weight percent electrode active material and about 1 to about 3 weight percent binder.

[0341] Roll-to-roll dry coating process

[0342] Advantageously, the method of the present invention enables continuous application of the electrode composition(s) (i.e., the first and / or second electrode composition) to the perforated current collector. Such continuous application may be carried out, inter alia, by using a roll-to-roll coating system. The roll-to-roll coating system is designed to automate the unrolling, coating, and re-rolling of the current collector foil while ensuring uniform application of the electrode composition(s). Unrolling the current collector foil may be performed by placing a large spool of the current collector foil at the start of the roll-to-roll system and continuously unrolling the foil and feeding it into the processing line using tension-controlled rollers to ensure a consistent and wrinkle-free surface. The electrode composition(s) may then be applied to the current collector and laminated thereto in a continuous manner. After lamination, the coated current collector foil is continuously wound onto a take-up roll at the end of the system.

[0343] The components of the electrode composition(s) (i.e., the first and / or second electrode composition) may be mixed together in a dry state, forming a powder composition with uniform particle distribution. Advanced blending techniques, such as high-energy ball milling or dry powder mixers, may be employed to ensure that the binder, and optionally, conductive additives are evenly dispersed among the active material particles. In some embodiments, the electrode composition is obtained by dry mixing components of the electrode composition and subjecting an obtained drymixture to a fibrilization process. In some embodiments, the fibrilization process is followed by grinding and / or sieving.

[0344] The electrode composition(s) (i.e., the first and / or second electrode composition) may be processed to be in a form of a film prior to or when being applied to the at least first surface of the perforated current collector. For example, the dry powder mixture may be processed into a film using a rolling device with two rotating rolls. The rolls may be rotated at different speeds, thereby creating a shearing force that aligns the fibrils in the powder mixture and / or compacting the film. The rolling device can be configured as a calendering device. Additionally or alternatively, at least one of the rolls may be heatable.

[0345] The electrode composition in the form of a film may be prepared at a temperature ranging from about 80°C to about 120°C. The speed of foil formation may range from about 0.5 m / min to about 10 m / min. The linear force applied to the dry mixture between the two rollers may range from about 100 N / cm to about 10 kN / cm. In some embodiments, the lamination is performed by applying a press force of about 60-150 kN.

[0346] After formation, the film may be applied (laminated) onto the perforated current collector. Film formation and lamination may be performed sequentially or simultaneously. The dry film may be directly laminated onto the perforated current collector by aligning the current collector with the faster rotating roll at a speed matching the rotation of said roll. In some embodiments, the current collector is moved over the roll while the dry film is formed on the current collector, thereby simultaneously forming the dry film and laminating it to the current collector.

[0347] Preferably, both the first and the second electrode compositions are applied to both surfaces of the perforated current collector (i.e., the first surface and the second surface). In some embodiments, the electrode compositions are applied to both surfaces of the perforated current collector simultaneously. In certain such embodiments, two pairs of rollers may be used, positioned to process the electrode compositions into two dry films and apply said films to both surfaces of the current collector positioned between said two pairs of rollers. Alternatively, a single pair of rollers may be used, wherein a current collector is positioned between two rollers to form a film directly on both surfaces. This method involves pressing the perforated current collector betweentwo rollers, each carrying a layer of dry powder, so that the powder is compacted directly onto both sides of the foil in a single step.

[0348] A thickness of the first electrode composition applied to at least the first side of the perforated current collector may range from about 5 pm to about 500 pm. In some embodiments, the thickness of the first electrode composition ranges from about 5 pm to about 250 pm. In further embodiments, the thickness of the first electrode composition ranges from about 25 pm to about 200 pm, or from about 50 pm to about 150 pm. Each possibility represents a separate embodiment of the invention.

[0349] It is to be understood that following application of the electrode composition(s) to the at least one surface of the perforated current collector, having a nonplanar surface, the degree of the deviation from the planar structure is configured to be reduced, thereby optimizing the contact between the electrode composition and the perforated current collector, ensuring enhanced efficiency of the energy storage and / or generation device.

[0350] In some embodiments, the 3D thickness of the perforated current collector is reduced by at least about 10% following application of the electrode composition(s) (i.e., the first and / or second electrode composition). In further embodiments, the 3D thickness of the perforated current collector is reduced by at least about 30%. In yet further embodiments, the 3D thickness of the perforated current collector is reduced by at least about 50%. In still further embodiments, the 3D thickness of the perforated current collector is reduced by at least about 60%. In yet further embodiments, the 3D thickness of the perforated current collector is reduced by at least about 80%. In yet further embodiments, the 3D thickness of the perforated current collector is reduced by at least about 90%. In still further embodiments, the 3D thickness of the perforated current collector is reduced by at least about 99%. In certain embodiments, the 3D perforated current collector becomes essentially flat following application of the electrode composition(s).

[0351] Figure 9 schematically illustrates dry coating system 401 for producing a single-sided electrode, in accordance with some embodiments. System 401 is configured as a continuous roll-to-roll process and comprises a series of rollers and processing units arranged to compact solid components of an electrode composition and laminate a resulting standalone dry electrode film onto a perforated current collector.In the illustrated embodiment, dry electrode composition 421 is supplied to a rolling and compaction section comprising at least first roller 403 and a second roller 405, which can be configured to rotate at different speeds to apply shear forces to the dry composition. The differential roller speeds promote binder fibrilization and alignment of fibrils within the electrode composition. Additional roller 407 may further compact and densify the electrode composition, thereby forming a self-supporting solid electrode film 423. Electrode film 423 is subsequently conveyed toward lamination rollers 411 and 413, where it is laminated onto perforated current collector 425 conveyed by roller 409 under applied pressure and / or temperature to produce single- sided electrode 427.

[0352] Figure 10 schematically illustrates dry coating system 501 for producing a double-sided electrode, in accordance with some embodiments. System 501 is configured to laminate a first dry electrode film and a second dry electrode film onto opposing surfaces of a perforated current collector in a continuous roll-to-roll process.

[0353] In the illustrated embodiment, first dry electrode film 523 and second dry electrode film 525 are independently formed by compaction and fibrilization of corresponding dry electrode compositions using respective rolling assemblies (schematically shown as rollers 503 and 505). Each rolling assembly may comprise a pair of rollers rotating at different speeds to induce binder fibrilization and film formation, as well as at least one additional pair of rollers for further electrode film compaction, as described with respect to Figure 9. Perforated current collector 527 is conveyed by roller 507 between first dry electrode film 523 and second dry electrode film 525 and enters a lamination zone including a pair of rollers 509 and 511, where both films are simultaneously laminated onto opposite surfaces of the current collector under applied pressure and / or temperature, thereby forming double-sided dry-coated electrode 529.

[0354] While the perforated current collectors in Figures 9 and 10 are shown as a planar metal foil comprising a plurality of through-holes illustrated as cylindrical holes, the current collector may be non-planar and / or the holes may be tapered, in accordance with some embodiments of the invention.Electrode based on the perforated current collector and its application in the energy storage and / or generation device

[0355] Further provided is an electrode prepared by the method according to the various aspects and embodiments disclosed hereinabove. According to some embodiments, the electrode is a cathode.

[0356] In some embodiments, the electrode includes the perforated current collector and the first electrode composition applied to the first surface thereof. Preferably, the electrode includes the perforated current collector and an electrode composition applied to the first and to the second surface thereof.

[0357] As explained hereinabove, the nonplanar structure of at least the first surface of the current collector may not be maintained. However, it is important to note that the electrode is prepared using a current collector that has at least one nonplanar surface.

[0358] The electrode composition may include the components, as described hereinbelow, including, inter alia, the electrode active material, binder and, optionally, conductive additive.

[0359] In some embodiments, the thickness of the first electrode composition on the first surface is at least about 1% lower than the thickness of the second electrode composition on the second surface of the perforated current collector. In further embodiments, the thickness of the first electrode composition on the first surface is at least about 5% lower than the thickness of the second electrode composition on the second surface of the perforated current collector. In yet further embodiments, the thickness of the first electrode composition on the first surface is at least about 10% lower than the thickness of the second electrode composition on the second surface of the perforated current collector.

[0360] In some embodiments, at least about 90% of a total volume of the plurality of holes of the perforated current collector in said electrode is filled by the electrode composition(s). In certain embodiments, at least about 95% of a total volume of the plurality of holes of the perforated current collector in said electrode is filled by the electrode composition. The degree of hole occupancy by the electrode composition(s) may be assessed by optical or electronic microscopy imaging of a cross-sectioned electrode.The reference to the percentage of the total volume of the plurality of holes being filled by the electrode composition(s) (the first electrode composition, second electrode composition or combined) is made specifically to the geometrical volume of the holes in the perforated current collector that is occupied by the electrode composition. This does not include or refer to the inherent porosity of the electrode composition itself. In this context, the filled volume is measured as the volume of the open voids in the perforated current collector that is physically occupied by the electrode composition after application thereof. It should be made clear that the term “total volume of the plurality of holes being filled by the electrode composition" assumes the electrode composition as a bulk material, which may inherently have a certain level of porosity (e.g., micro- or nano-scale pores within the electrode structure), however, this porosity does not affect the calculation of whether the holes are considered "filled". In other words, if the electrode composition fills the structural voids of the perforated current collector to 90% of their geometrical volume, it is regarded as "filled," regardless of the internal porosity of the electrode material.

[0361] In some embodiments, the first electrode composition is in direct contact with at least the first surface of the perforated current collector. In further embodiments, the first surface of the perforated current collector is in a direct contact with the first electrode composition and the second surface of the perforated current collector is in a direct contact with the second electrode composition. In some currently preferred embodiments, there is no intermediate layer between the electrode compositions and the first surface and / or second surface of the perforated current collector. Preferably, the first electrode composition disposed on the first surface of the perforated current collector and the second electrode composition disposed on the second surface thereof are combined through the plurality of holes of the perforated current collector.

[0362] The density of the first electrode composition on the first surface of the perforated current collector and / or the density of the second electrode composition(s) on the second surface thereof may be at least about 3.1 g / cm3. In some embodiments, the density of the first electrode composition and / or the density of the second electrode composition is at least about 3.3 g / cm3. In certain embodiments, the density of the first electrode composition and / or the density of the second electrode composition is at least about 3.5 g / cm3.The overall thickness of the electrode may range from about 20 |am to about 1000 |am. In some embodiments, the overall thickness of the electrode ranges from about 50 |am to about 750 |am. In further embodiments, the overall thickness of the electrode ranges from about 100 |am to about 500 |am.

[0363] According to some embodiments, the perforated current collector combines the structural features of a non-planar surface with tapered holes. In this configuration, the current collector has a non-planar surface comprising embossed elements, and further comprises a plurality of holes wherein the mean hole opening area on the first surface differs from the mean hole opening area on the second surface by at least about 20%. This combination may provide a synergistic effect, where the mesoscale three-dimensional structure and the microscopic tapering of the holes work together to further enhance the anchoring and packing density of the electrode composition during the dry coating process.

[0364] Thus, according to some embodiments, there is provided a perforated current collector in a form of a metal foil comprising: a plurality of holes; a first surface, and a second surface opposite the first surface, wherein the first section of the first surface is non-planar, and a mean hole opening area of the plurality of holes on the first surface differs from a mean hole opening area of the plurality of holes on a second surface of the perforated current collector, by at least about 20%.

[0365] According to some embodiments, the electrode is prepared using a perforated current collector that is both non-planar and comprises a plurality of tapered holes. The resulting electrode benefits from both the initial non-right- angle engagement caused by the non-planar surface and the funneling effect provided by the tapered holes, leading to superior material adhesion, density, and overall electrochemical performance.

[0366] According to some embodiments, where the current collector is both non-planar and comprises tapered holes, the direction of the tapering is selected to be synergistic with the local orientation of the non-planar surface. The tapering of the holes is thereby oriented relative to the local slope of the surface such that the non-right- angle orientation of the inner wall surfaces, relative to the longitudinal plane, is maintained or enhanced. According to some embodiments, the tapering of the holes and the local slope of the non-planar surface do not contribute in opposing angular directions. According to some embodiments, the tapering of the holes and the local slope of thenon-planar surface do not contribute in opposing angular directions in a manner that would cause an inner wall surface to become substantially perpendicular to the longitudinal plane of the collector.

[0367] In view of the forgoing, there is provided an energy storage and / or generation device that includes at least one electrode, wherein the electrode is prepared by the method disclosed herein. Dry-coated electrodes can be used in a wide range of energy storage and / or generation devices, including but not limited to, batteries (or cells), capacitors, and fuel cells. Said electrodes are particularly suited for lithium-ion batteries (Li-ion) due to their high energy density requirements, solid-state batteries where solvent-free processes are critical, and sodium-ion batteries as a cost-effective alternative. Additionally, the dry coated electrodes are applicable in supercapacitors for high power density applications and redox flow batteries, which benefit from efficient electrode production.

[0368] In some embodiments, the energy storage and / or generation device includes a battery or a cell. Preferably, the battery is a secondary battery. In some embodiments, the cell or the battery includes at least one electrode that is obtained by applying an electrode composition to a perforated current collector having a plurality of holes, using a dry coating process, wherein at least a portion of the plurality of holes have an inner wall surface that forms a non-right angle with a longitudinal plane of the current collector, as described herein.

[0369] It is noted herein that while a cell is a single unit of device that converts chemical energy into electrical energy, and a battery may include a collection of cells that converts chemical energy into electrical energy, the terms “cell” and “battery” are used herein interchangeably.

[0370] Non-limiting examples of batteries which can benefit significantly from the use of dry coated electrodes include lithium-ion batteries, lithium-metal batteries, lithiumsulfur batteries, and zinc-air batteries, wherein lithium-ion batteries can include, for example, silicon-anode batteries and nickel-rich cathode batteries.

[0371] Furthermore, there is provided an electric device or system that includes the cell, an array of cells, the battery or an array of batteries, as provided herein. The electric devices or systems which are contemplated within the scope of the present invention, include any electric device or system that can use the cell or the battery provided hereinas a main, auxiliary or minor source of energy. Alternatively, an electric device or system is one that includes at least one battery according to the present invention, wherein the device uses the electricity stored in the battery as its power source.

[0372] Examples of electric devices include, without limitation, an electric vehicle for transportation in air, land, water and / or space, a smartphone, a laptop computer, a portable media player, a power tool, a toy, a heating device, a colling device, an article for illumination (e.g., flashlight), and the likes. It is to be understood that electric vehicles for transportation include both vehicles that are solely powered by electricity (e.g., via batteries) and hybrid vehicles that one of their power sources comprises a battery.

[0373] Non-limiting examples of electric systems include electric grids, such as those incorporating solar and wind generation systems, as well as other grid types such as utility-scale grids, microgrids, island grids, industrial grids, residential grids, commercial grids, smart grids, and hybrid grids.

[0374] It is expected that during the life of a patent maturing from this application many relevant tools and methods for continuous electrodeposition of electrically conducting foils will be developed and the scope of the phrase "processes for manufacturing of patterned drums and foils" is intended to include all such new technologies a priori.

[0375] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

[0376] As used herein the term “about” refers to ±10 %. For example, the term “about 100 pm” encompasses the value 100 pm, as well as the values 90 pm, 91 pm, 92 pm, 93 pm, 94 pm, 95 pm, 96 pm, 97 pm, 98 pm, 98 pm, 99 pm, 100 pm, 101 pm, 102 pm, 103 pm, 104 pm, 105 pm, 106 pm, 107 pm, 108 pm, 109 pm, and 110 pm.

[0377] The terms "comprises", "comprising", "includes", "including", “having” and their conjugates mean "including but not limited to".The term “consisting of’ means “including and limited to”.

[0378] The term "consisting essentially of" means that the composition, method or structure may include additional ingredients, steps and / or parts, but only if the additional ingredients, steps and / or parts do not materially alter the basic and novel characteristics of the claimed composition, method or structure.

[0379] As used herein, the phrase “selected from the group consisting of’ includes all members of the recited group, each member of the recited group, and all possible combinations. For example, selected from the group consisting of A, B, and C, includes A, only, as well as B, only, as well as C, only, as well as A and B, as well as A and C, as well as B and C, and as well as A, B, and C.

[0380] As used herein, and unless expressly stated otherwise, the phrase "substantially" or "substantially all" refers to at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 99%, or at least 99.9% of the condition being fulfilled. Each possibility is a separate embodiment. As an illustrative example, the phrase "substantially all of the external surface of the drum, provided in step (a), is metallic" refers to at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 99%, or at least 99.9% of the external surface being metallic.

[0381] As used herein, the phrases "substantially devoid of" and / or "essentially devoid of" in the context of a certain substance, refer to a composition that is totally devoid of this substance or includes less than about 5, 1, 0.5 or 0.1 percent of the substance by total weight or volume of the composition. Alternatively, the phrases "substantially devoid of" and / or "essentially devoid of" in the context of a process, a method, a property or a characteristic, refer to a process, a composition, a structure or an article that is totally devoid of a certain process / method step, or a certain property or a certain characteristic, or a process / method wherein the certain process / method step is affected at less than about 5, 1, 0.5 or 0.1 percent compared to a given standard process / method, or property or a characteristic characterized by less than about 5, 1, 0.5 or 0.1 percent of the property or characteristic, compared to a given standard.

[0382] When applied to an original property, or a desired property, or an afforded property of an object or a composition, the term “substantially maintaining”, as used herein, means that the property has not change by more than 20 %, 10 % or more than 5 % in the processed object or composition.The term “exemplary” is used herein to mean “serving as an example, instance or illustration”. Any embodiment described as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments and / or to exclude the incorporation of features from other embodiments.

[0383] The words “optionally” or “alternatively” are used herein to mean “is provided in some embodiments and not provided in other embodiments”. Any particular embodiment of the invention may include a plurality of “optional” features unless such features conflict.

[0384] As used herein, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise. For example, the term "a compound" or "at least one compound" may include a plurality of compounds, including mixtures thereof.

[0385] Unless stated otherwise, when reference is made herein to a percentage, fraction, average value, or mean value relating to the current collector, such value is understood to refer to a value determined over a representative portion of the current collector. In some embodiments, the perforation pattern and the three-dimensional pattern of the current collector are periodic. In such embodiments, a defined section of the foil in which the perforation pattern and / or the three-dimensional pattern repeat periodically may be used to evaluate such percentage or mean value. By way of example, the defined section may include at least 5, at least 10, at least 20, at least 100, or at least 500 repetitions of each pattern. Values determined over such a representative section are considered representative of the entire current collector.

[0386] Throughout this application, various embodiments of this invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.Whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range. The phrases “ranging / ranges between” a first indicate number and a second indicate number and “ranging / ranges from” a first indicate number “to” a second indicate number are used herein interchangeably and are meant to include the first and second indicated numbers and all the fractional and integral numerals therebetween.

[0387] As used herein the terms “process” and "method" refer to manners, means, techniques and procedures for accomplishing a given task including, but not limited to, those manners, means, techniques and procedures either known to, or readily developed from known manners, means, techniques and procedures by practitioners of the chemical, material, mechanical, computational and digital arts.

[0388] Unless otherwise defined, all technical and / or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and / or materials are described below. In case of conflict, the patent specification, including definitions, will prevail. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.

[0389] Various embodiments and aspects of the present invention as delineated hereinabove and as claimed in the claims section below find experimental support in the following examples.

[0390] EXAMPLES

[0391] Example 1 - Electrode lamination - dual sided, 3D

[0392] Aluminum 3D (embossed) perforated current collector was provided having a local thickness of about 12 pm and a 3D thickness of about 50 pm. The embossing pattern included circular embossed and debossed elements arranged in a square packing.

[0393] Dry cathode mixture containing 95 %wt NMC, 1 %wt PTFE, and 4 %wt carbon black was prepared and laminated to both surfaces of the current collector by using two pairs of calendaring rollers, wherein each pair produces a dry electrode film withfibrillated binder therebetween and the current collector is passed between the two pairs of rollers, with each electrode film being disposed between a roller surface and the current collector.

[0394] For comparison, the same procedure was applied to a flat aluminum perforated current collector that was not embossed, having the same local thickness as the 3D perforated current collector.

[0395] Example 2 - Electrode adhesion testing (3D)

[0396] Following lamination, the laminated current collector was punched into pouch cell-sized electrodes and the electrodes were visually observed and tested for delamination and adhesion.

[0397] Visual inspection of the obtained electrodes showed that the 3D and flat perforated current collectors provided a visually homogeneous and good adhesion of the electrode composition on both sides thereof.

[0398] The electrodes where then cut into circular samples having a diameter of 15 mm and an adhesion test using a stamp removal test was performed on ZwickRoell zwickiLine Z2.5 device using the following test parameters: pressure load of 68N, holding time of 10s, and test speed of 4 mm / min. It was found that the adhesion strength of the electrode based on the 3D current collector was more than 10% higher than that of the flat current collector (9 N / cm2and 8 N / cm2,respectively).

[0399] Example 3 - Electrode lamination - single sided, 3D

[0400] Single-sided electrodes were prepared as described in Example 1, except that the dry cathode film was laminated to one surface of the current collector by using two pairs of calendaring rollers, which produces a dry electrode film with fibrillated binder between one pair of rollers and the current collector is passed between the other pair of rollers together with the electrode film.

[0401] Example 4 - Electrochemical cell testing (3D)

[0402] The single sided electrodes, which preparation is described in Example 1 were used as cathodes in coin cells. Anodes were prepared by dry coating of an electrode composition containing 98 wt.% graphite and 2 wt.% PTFE on one side of a flat nonperforated copper foil primed with an adhesion-promoting coating. The electrolyteformulation was 1 M LiPFe in a 1:1 EC / DMC solvent mixture with 2 vol.% vinylene carbonate additive.

[0403] Table 1 below summarizes the characteristics of the cathodes used in the coin cells.

[0404] Table 1: cathodes characteristics

[0405]

[0406] It may be seen from Table 1 that while essentially the same electrode composition was applied to the flat (2D) and embossed (3D) current collectors, the electrode volumetric density obtained when using the embossed current collector was 9% higher than that of the electrode formed on the flat current collector, even though the active material weight of the 3D cell cathode is lower. It is therefore stipulated that the use of the perforated current collector having a non-planar surface enables higher electrode material packing of the electrode.

[0407] Table 2 outlines the cell cycling test conditions. Reference performance test (RPT) was performed by charging and discharging the cell to 50%, followed by discharging for 18 seconds at 1.5C and charging for 18 seconds at 1.5C. Cell resistance was calculated from voltage drop during the current pulse.

[0408] Table 2: coin cells cycling conditions

[0409]

[0410]

[0411] <

[0412] The results of the cell cycling as represented by discharge capacity are shown graphically in Figure 4. It may be seen that the cell which contained the cathode that was based on the perforated current collector having a nonplanar surface (squares) outperformed the cell with the cathode based on the flat perforated current collector (triangles) at every cycle, wherein the relative advantage of the 3D perforated current collector was particularly significant at charge and / or discharge rates of 1C and higher.

[0413] Assuming a discharge capacity measured at C / 10, the volumetric energy density of the cell utilizing a cathode based on the 3D perforated current collector was 10.5% higher compared to that of the cell with a flat perforated current collector.

[0414] The RPT tests showed a lower resistance for the 3D perforated current collector cell at all the RPT charge and discharge cycles as compared to the flat perforated current collector cell.

[0415] Example 5 - Electrode lamination (tapered holes)

[0416] Aluminum perforated current collector with tapered holes was provided having a thickness of about 12 pm. The mean hole opening area on the current collector surface with larger hole openings was about 13,500 pm2and on the surface with smaller hole openings the mean area was about 10,000 pm2.

[0417] Dry cathode mixture containing 95 %wt NMC, 1 %wt PTFE, and 4 %wt carbon black was prepared and laminated to both surfaces of the current collector by using two pairs of calendaring rollers, wherein each pair produces a dry electrode film with fibrillated binder therebetween and the current collector is passed between the two pairs of rollers, with each electrode film being disposed between a roller surface and the current collector.For comparison, the same procedure was applied to an aluminum perforated current collector with essentially straight (or cylindrical) hole walls, the mean hole opening area on both surfaces of the current collector being about 13,000 pm2.

[0418] Example 6 - Electrode adhesion testing (tapered holes)

[0419] Following lamination, the laminated current collector having tapered holes was punched into pouch cell-sized electrodes and the electrodes were visually observed and tested for delamination and adhesion.

[0420] Visual inspection of the obtained electrodes showed that the perforated current collector with tapered holes provided a visually homogeneous and good adhesion of the electrode composition on both sides thereof.

[0421] The electrodes were then cut into circular samples having a diameter of 15 mm and an adhesion test using a stamp removal test was performed on ZwickRoell zwickiLine Z2.5 device using the following test parameters: pressure load of 68N, holding time of 10s, and test speed of 4 mm / min. It was found that the adhesion strength of the electrode based on the current collector with tapered holes was more than 10% higher than that of the current collector with cylindrical holes (9 N / cm2and 8 N / cm2,respectively).

[0422] It was further found that the thickness of the electrode composition on the tapered current collector surface with the larger hole openings was about 55 pm and on the surface with the smaller hole openings about 70 pm.

[0423] Example 7 - Electrochemical cell testing (tapered holes)

[0424] Single-sided electrodes were prepared as described in Example 5, except that the dry cathode film was laminated to one surface of the current collector by using two pairs of calendaring rollers, which produces a dry electrode film with fibrillated binder between one pair of rollers and the current collector is passed between the other pair of rollers together with the electrode film. The electrodes were used as cathodes in coin cells.

[0425] Anodes were prepared by dry coating of an electrode composition containing 98 wt.% graphite and 2 wt.% PTFE on a single side a flat non-perf orated copper foil primed with an adhesion-promoting coating.The electrolyte formulation was 1 M LiPFe in a 1:1 EC / DMC solvent mixture with 2 vol.% vinylene carbonate additive.

[0426] Table 3 below summarizes the characteristics of the cathodes used in the coin cells.

[0427] Table 3: cathodes’ characteristics

[0428]

[0429] It may be seen from Table 3 that while essentially the same electrode composition was applied to the “tapered” and “straight” current collectors, the electrode volumetric density obtained when using the current collector with tapered holes was 9% higher than that of the electrode formed on the current collector with straight holes, even though the active material weight of the tapered cell cathode is lower. It is therefore stipulated that the use of the perforated current collector having a mean hole opening on the opposite surfaces of the current collector that differ by at least about 20% enables denser electrode material packing of the electrode.

[0430] Table 4 outlines the cell cycling test conditions. Reference performance test (RPT) was performed by charging and discharging the cell to 50%, followed by discharging for 18 seconds at 1.5C and charging for 18 seconds at 1.5C. Cell resistance was calculated from voltage drop during the current pulse.

[0431] Table 4: coin cells cycling conditions

[0432]

[0433] <

[0434]

[0435] The results of the cell cycling as represented by discharge capacity are shown graphically in FIG. 7. It may be seen that the cell which contained the cathode that was based on the perforated current collector having different hole opening areas on the opposite surfaces (squares) outperformed the cell with the cathode based on the perforated current collector with essentially similar hole openings (triangles) at every cycle, wherein the relative advantage of the “tapered” perforated current collector was particularly significant at charge and / or discharge rates of 1C and higher.

[0436] Assuming a discharge capacity measured at C / 10, the volumetric energy density of the cell utilizing a cathode based on the perforated current collector with tapered holes was up to 13.5% higher compared to that of the cell with the perforated current collector with straight holes.

[0437] The RPT tests showed a lower resistance for the tapered cell at all the RPT charge and discharge cycles as compared to the flat cell.

[0438] Example 8 - 3D electrodes having conical holes

[0439] Figures 8A-E are optical microscopy image of coated electrode manufactured through a dry-coating process using different perforated current collectors. In particular, Figure 8A shows an optical microscopy image of a one-sided coated electrode manufactured through a dry-coating process using a perforated current collector having a planar surface and cylindrical holes. Figure 8B shows an optical microscopy imageof a one-sided coated electrode manufactured through a dry-coating process using a perforated current collector having a planar surface and conical holes. Figure 8C shows an optical microscopy image of a one-sided coated electrode manufactured through a dry-coating process using a perforated current collector having a non-planar surface and conical holes. Figure 8D shows an optical microscopy image of a dual-sided coated electrode manufactured through a dry-coating process using a perforated current collector having a planar surface and cylindrical holes. Figure 8E shows an optical microscopy image of a dual-sided coated electrode manufactured through a dry-coating process using a perforated current collector having a non-planar surface and conical holes.

[0440] It can be seen that, when dry coating is applied from only one side of a planar perforated foil having cylindrical holes, the holes are substantially or completely filled by the electrode material, leaving insufficient free volume to receive electrode material applied from the opposite side. This limits through-hole interlocking and reduces mechanical anchoring between coatings on opposing sides. In contrast, in a planar or 3D-formed foil having conical holes, the tapered geometry promotes partial filling from each side, such that electrode material deposited from both sides contacts and engages the hole sidewalls, where mechanical anchoring is enhanced. The resulting interlocking of electrode material within the conical perforations improves adhesion and mechanical integrity of the coated electrode. This effect may be further observed by comparing the dual-sided coated electrodes shown in Figures 8D and 8E. While the planar current collector with cylindrical holes exhibits insufficient mechanical integrity, leading to partial detachment of the electrode layers from the current collector, the enhanced interlocking of the electrode layers within the tapered holes of the three-dimensional current collector maintains the electrode layers closely attached to the current collector surfaces.

[0441] The cross-sectional structure of the current collector prior to electrode lamination is shown in Fig. 3. It can be seen that the 3D structure of the current collector was not retained following the dry coating process.

[0442] It is the intent of the applicant(s) that all publications, patents and patent applications referred to in this specification are to be incorporated in their entirety by reference into the specification, as if each individual publication, patent or patent application was specifically and individually noted when referenced that it is to beincorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. To the extent that section headings are used, they should not be construed as necessarily limiting. In addition, any priority document(s) of this application is / are hereby incorporated herein by reference in its / their entirety.

Claims

1. CLAIMS1. A method for manufacturing an electrode, comprising:providing a perforated current collector comprisinga plurality of holes and havinga first surfaceand a second surface opposite the first surface,the perforated current collector being configured such that inner wall surfaces of at least a portion of the plurality of holes are oriented at a non-right angle relative to a longitudinal plane of the current collector; andapplying a first electrode composition to at least a first section of the first surface using a dry coating process while the first electrode composition is disposed generally parallel to the longitudinal plane, thereby bringing the first electrode composition into contact with said inner wall surfaces at said non-right angle.

2. The method of claim 1, wherein the first section of the first surface is non-planar.

3. The method of claim 2, wherein the non-planar first section comprises elements selected from the group consisting of peaks, protrusions, ridges, bulges, bumps, creases, valleys, and depressions.

4. The method of claim 3, wherein the embossed elements are aligned in straight or tilted lines relative to a longitudinal axis of the perforated current collector.

5. The method of claim 3, wherein the embossed elements comprise periodically alternating round bulges and depressions arranged in a seamless repeating embossing pattern.

6. The method of claim 5, wherein a horizontal distance between centers of two adjacent bulges or depressions ranges from about 100 pm to about 1000 pm.

7. The method of any one of claims 5 or 6, wherein a vertical distance between a highest point of a bulge and a lowest point of an adjacent depression ranges from about 20 pm to about 100 pm.

8. The method of claim 7, wherein said vertical distance is about 2 to 8 times higher than a local thickness of the perforated current collector.

9. The method of any one of claims 7 or 8, wherein a vertical distance is reduced by at least about 80% following application of the first electrode composition.

10. The method of any one of claims 1 to 9, wherein the plurality of holes of the perforated current collector are arranged in a seamless repeating perforation pattern.

11. The method of any one of claims 1 to 10, comprising applying the first electrode composition to at least the first surface of the perforated current collector.

12. The method of any one of claims 1 to 11, wherein the plurality of holes have a mean opening size ranging from about 50 pm to about 500 pm.

13. The method of any one of claims 1 to 12, wherein an open area of the perforated current collector ranges from about 1% to about 40%.

14. The method of any one of claims 1 to 13, wherein the perforated current collector is made of a metal selected from the group consisting of aluminum, copper, nickel, stainless steel, silver, zinc, tin, iron, titanium, and any combination or alloy thereof.

15. The method of any one of claims 1 to 14, wherein the application of the first electrode composition is performed in a roll-to-roll system, and comprises laminating the first electrode composition and the perforated current collector between a pair of rollers.

16. The method of any one of claims 1 to 15, wherein the first electrode composition is present in the form of a film.

17. The method of claim 15, wherein the first electrode composition is present in the form of a film, and wherein the lamination comprises applying pressure so that the first electrode composition and the perforated current collector are pressed one against the other and the first section of the first surface becomes at least partially flattened.

18. The method of any one of claims 1 to 17, wherein the first electrode composition contains less than about 10 wt% solvent, based on the total weight of the first electrode composition.

19. The method of any one of claims 1 to 18, wherein the first electrode composition comprises an electrode active material selected from the group consisting of lithium nickel manganese cobalt oxide (NMC), lithium iron phosphate (LFP), lithium iron manganese phosphate, lithium nickel manganese oxide, lithium cobalt oxide, lithium nickel cobalt aluminum oxide, lithium cobalt aluminum oxide, lithium titanium oxide, sulfur, lithium sulfide, graphite, silicon oxide, and any combination thereof20. The method of claim 19, wherein the electrode active material is present in a weight percent ranging from about 90 wt% to about 100 wt% based on the total weight of the first electrode composition.

21. The method of any one of claims 1 to 20, wherein the first electrode composition comprises a binder selected from the group consisting of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), cellulose, and any derivatives thereof.

22. The method of claim 21, wherein the binder is present in a weight percent of no more than 2 wt% based on the total weight of the first electrode composition.

23. The method of any one of claims 1 to 22, comprising applying a second electrode composition to at least a second section of a second surface of the perforated current collector, wherein the second surface is in an opposite side to the first surface of the current collector, and wherein the second section of the second surface is non-planar.

24. The method of any one of claims 22 to 23, wherein the second electrode composition is essentially the same as the first electrode composition.

25. The method of any one of claims 22 to 24,wherein each one of the first electrode composition and the second electrode composition is provided in the form of a fdm;wherein the application of both electrode compositions is performed together in a roll-to-roll system, and comprises laminating the perforated current collector, the first electrode composition, and the second electrode composition between a pair of rollers, so that the perforated current collector is positioned between the electrode composition fdms;wherein the lamination comprises applying pressure so that current collector is pressed between the electrode compositions, and each one of the first section of the first surface and the second section of the second surface becomes at least partially flattened.

26. An electrode prepared by the method of any one of claims 1 to 25.

27. The electrode of any one of claims 25 or 26, wherein the volumetric density of each of the first electrode composition and the second electrode composition is at least about 3.1 g / cm3.

28. The method of any one of claims 1 to 25, wherein:a mean hole opening area of the plurality of holes on the first surface differs from a mean hole opening area of the plurality of holes on a second surface of the perforated current collector, by at least about 20%, wherein the second surface is in an opposite side to the first surface of the current collector.

29. The method of claim 28, wherein the mean hole opening area of the plurality of holes on the first surface is at least about 25% larger than the mean hole opening area of the plurality of holes on the second surface.

30. The method of claim 28 or claim 29, wherein the mean hole opening area on the first surface ranges from about 2,000 pm2to about 0.15 mm2.

31. The method of any one of claims 28 to 30, wherein the mean hole opening area on the second surface ranges from about 1,500 pm2to about 0.12 mm2.

32. The method of any one of claims 28 to 31, wherein the plurality of holes on the first surface have a mean opening size ranging from about 50 pm to about 500 pm.

33. The method of any one of claims 28 to 32, wherein the plurality of holes on the second surface have a mean opening size ranging from about 40 pm to about 400 pm.

34. The method of any one of claims 28 to 33, wherein the plurality of holes of the perforated current collector are arranged in a seamless repeating perforation pattern.

35. The method of any one of claims 28 to 34, wherein the first electrode composition is present in the form of a film and wherein the first electrode composition is present in the form of a film, and wherein the lamination comprises applying pressure so that the first electrode composition and current collector are pressed one against the other.

36. The method of any one of claims 28 to 35, comprising applying a second electrode composition to at least a second section of the second surface of the perforated current collector.

37. The method of claim 36,wherein each one of the first electrode composition and the second electrode composition is provided in the form of a fdm;wherein the application of both electrode compositions is performed together in a roll-to-roll system, and comprises laminating the perforated current collector and electrode compositions between a pair of rollers, so that the perforated current collector is positioned between the electrode composition fdms;wherein the lamination comprises applying pressure so that current collector is pressed between the electrode compositions.

38. The method of any one of claims 36 to 37, wherein upon application of both the first electrode composition and the second electrode composition to the perforated current collector, at least 90% of the total surface of the perforated current collector becomes covered by the electrode compositions.

39. The method of any one of claims 36 to 38, wherein upon application of both the first electrode composition and the second electrode composition to the perforated current collector the first electrode composition contacts the second electrode composition through at least some of the plurality of holes.

40. An electrode prepared by the method of any one of claims 28 to 39.

41. The electrode of claim 40, wherein at least about 90% of a total volume of the plurality of holes of the perforated current collector is filled by the electrode composition.

42. The electrode of any one of claims 40 or 41, wherein the density of the electrode composition is at least about 3.1 g / cm3.

43. The electrode of any one of claims 40 to 42, wherein the first electrode composition is in a direct contact with at least the first surface of the perforated current collector.

44. The electrode of any one of claims 40 to 43, wherein the mean hole opening area of the plurality of holes on the first surface is at least about 20% larger than the mean hole opening area of the plurality of holes on the second surface and the thickness of the first electrode composition on the first surface is at least about 5% lower than the thickness of the second electrode composition on the second surface of the perforated current collector.

45. A perforated current collector in a form of a metal foil comprising:a plurality of holes;a first surfaceand a second surface opposite the first surfacewherein the first section of the first surface is non-planar, and a mean hole opening area of the plurality of holes on the first surface differs from a mean hole openingarea of the plurality of holes on a second surface of the perforated current collector, by at least about 20%.

46. The perforated current collector of claims 45, wherein inner wall surfaces of at least a portion of the plurality of holes are oriented at a non-right angle relative to a longitudinal plane of the current collector.

47. An electrode comprising the perforated current collector of any one of claims 45 to 46 and a first electrode composition, wherein the first electrode composition is in direct contact with at least the first surface of the perforated current collector.

48. The electrode of claim 47, further comprising a second electrode composition, wherein the first electrode composition is in direct contact with at least the second surface of the perforated current collector.

49. The electrode of any one of claims 47 to 48, wherein the first electrode composition, second electrode composition, or both comprises an electrode active material selected from the group consisting of lithium nickel manganese cobalt oxide (NMC), lithium iron phosphate (LFP), lithium iron manganese phosphate, lithium nickel manganese oxide, lithium cobalt oxide, lithium nickel cobalt aluminum oxide, lithium cobalt aluminum oxide, lithium titanium oxide, sulfur, lithium sulfide, graphite, silicon oxide, and any combination thereof.

50. The electrode of any one of claims 47 to 49, wherein at least about 90% of a total volume of the plurality of holes of the perforated current collector is filled by the first electrode composition, second electrode composition, or both.

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