Fabrication of anodes by pattern lamination, anodes fabricated thereby, and electrochemical devices incorporating such anodes

Abstract

The present invention relates to a method of forming anodes for electrochemical devices by laminating a metal foil to a current collector and creating pieces of anode active material, composed of the metal foil, which are spaced from each other by inter-piece regions, each inter-piece region providing a location for forming one or more electrical tabs of the finished anodes. The method may further include applying pieces of conductive coating to the current collector before laminating the metal foil to the current collector, each piece of conductive coating corresponding to one of the pieces of anode active material.In some embodiments, the conductive coating pieces may assist in forming the anode active material pieces and / or may improve the cycling performance of an electrochemical device fabricated using the anodes fabricated therewith. Also provided are anodes containing anode active material and conductive coatings applied to current collectors.

Description

Title of the invention: Fabrication of anodes by pattern lamination, anodes fabricated thereby, and electrochemical devices incorporating such anodes Data concerning related applications

[0001] The present application claims the benefit of priority from US Provisional Patent Application Serial No. 63 / 170,207, filed on April 2, 2021, and entitled "Manufacture of anodes by pattern lamination, anodes so manufactured, and secondary batteries incorporating such anodes." Domain

[0002] The present invention relates, in general, to the field of electrochemical devices. In particular, the present invention relates to the fabrication of anodes by pattern lamination, anodes thus fabricated, and electrochemical devices incorporating such anodes. Background to the invention

[0003] Rechargeable or secondary lithium metal batteries offer higher volumetric and gravimetric energy densities than current lithium-ion batteries. Unlike lithium-ion batteries, which contain anodes (negative electrode) formed from an intercalating material, such as graphite, in typical secondary lithium metal batteries, a lithium foil (anode active material) is laminated on both sides of a copper foil (current collector) to form the conventional lithium-copper-lithium (Li / Cu / Li) anode structure. However, lithium is soft and sticky, and it is difficult by conventional lamination processes to produce ultra-thin lithium foils (< 50 µm thick) having a width greater than 120 mm.This width constraint therefore limits the size of the anode and cells that can be manufactured using lamination techniques.

[0004] Figures 1A and 1B illustrate a conventional approach for producing conventional Li / Cu / Li anodes (represented by dotted regions 10) using a roll-to-roll process 12 involving the continuous lamination of ultra-thin lithium foil ribbons 14A and 14B on both sides of a copper foil strip 16 to form a strip anode precursor 18. The width, Ww, of the copper foil strip 16 is usually greater than the width, Wf, of the lithium foil, and the laminated structure typically has a bare copper region 16A along at least one edge of the copper foil strip. The bare copper region 16A is intended to form electrical tabs 10A to enable electrical contact with the Li / Cu / Li anodes 10 that are die-cut from the strip anode precursor 18 when the Li / Cu / Li anodes are assembled into a stacked "roll" of an electrochemical cell. Without the electrical tabs 10A, it would be difficult to connect multiple layers of the Li / Cu / Li anodes 10 of the stacked roll to an external electrical conductor (not shown) in the finished electrochemical cell.As mentioned above, due to the physical properties of lithium, the width Wf of the lithium foil strip 16 is limited to about 120 mm when using the desired ultra-thin lithium foil, and this limits the size of Li / Cu / Li anodes, such as the Li / Cu / Li anodes 10 of Figures 1A and 1B, which can be manufactured by conventional roll-to-roll lamination techniques, which severely limits the size of lithium metal electrochemical cells (not shown), e.g., lithium metal secondary battery cells, which can be manufactured with ultra-thin lithium metal anodes. In turn, this limitation hinders the development of lithium metal secondary cells for applications that require high-capacity batteries for practical operation, such as electric vehicles, among others. Summary of the invention

[0005] In one implementation, the present disclosure relates to a method of forming anodes for one or more electrochemical devices, wherein each of the anodes has an electrical tab.The method comprises providing a current collector strip; laminating, on a first side of the current collector strip, a metal foil to the current collector strip in the form of multiple pieces of anode active material spaced apart from each other so as to provide a strip anode precursor that comprises the pieces of anode active material and inter-piece regions not containing the metal foil; and forming the anodes from the strip anode precursor such that each anode is formed from a corresponding piece of anode active material and the corresponding electrical tab is formed from one of the inter-piece regions, wherein forming the anodes comprises separating the anodes from the strip anode precursor.

[0006] In one implementation, the anode forming method may include, prior to attaching the metal foil to the current collector strip, applying an electrically conductive coating at each location where the metal foil will be attached to the current collector strip and not applying the electrically conductive coating at each inter-piece region so as to form a piece of electrically conductive coating corresponding to a respective one of the pieces of anode active material. In some embodiments, the electrically conductive coating comprises electrically conductive particles and a binder.

[0007] In one implementation, the anode forming method further comprises attaching, on a second side of the current collector strip opposite the first side, the metal foil to the current collector strip as multiple pieces of anode active material on the reverse side spaced apart from each other and in alignment with respective corresponding pieces of the pieces of anode active material on the first side of the current collector strip.

[0008] In one implementation, each anode has an active area, and the method further comprises sizing a corresponding one of the pieces of anode active material to substantially correspond to the active area of the anode.

[0009] In one implementation, the anodes are formed at a 1:1 ratio to the pieces of anode active material.

[0010] In one implementation, the anodes are formed at a 2:1 ratio to the pieces of anode active material. Brief description of the drawings

[0011] For the purpose of illustrating aspects of the disclosure, the drawings illustrate elements and / or features of one or more embodiments of the disclosure. It should be understood, however, that the present disclosure is not limited to the precise arrangements and instruments shown in the drawings, in which:

[0012] [Fig. 1A] is a plan view of a portion of a conventional strip anode precursor in a conventional roll-to-roll lamination process, illustrating Li / Cu / Li anodes before the Li / Cu / Li anodes are die-cut from the strip anode precursor;

[0013] [Fig.1B] is an enlarged exaggerated cross-sectional view of the conventional strip-like Li / Cu / Li anode precursor along line 1B-1B of [Fig.1A] before anodes are die-cut from the strip-like anode precursor;

[0014] [Fig.2] is a flowchart illustrating an exemplary lamination process for anode formation of the present disclosure;

[0015] [Fig.3A] is a partial plan view of an exemplary strip anode precursor and an exemplary anode removed therefrom that may be manufactured using the method of [Fig.2], the strip anode precursor being shown at various processing stages, from application of a piece of optional conductive coating, to lamination of a piece of anode active material, to removal of the anode from the strip anode precursor;

[0016] [Fig.3B] is an enlarged exaggerated cross-sectional view of the anode example of [Fig.3A] along line 3B-3B of [Fig.3A];

[0017] [Fig.4] is a high-level schematic view of an exemplary roll-to-roll lamination process implementing the exemplary lamination process for anode formation of [Fig.2];

[0018] [Fig.5A], [Fig.5B], [Fig.5C], [Fig.5D] and [Fig.5E] are views in plan of portions of different strip anode precursors illustrating examples of alternative arrangements of anode regions and pieces of anode active material (and pieces of conductive coating, if any) on the strip anode precursors;

[0019] [Fig.6] is a graph of discharge capacity versus cycle life comparing the cycle life performance of the exemplary Li / Cu / Li anodes fabricated with and without a conductive coating layer of the present disclosure; and

[0020] [Fig.7] is a high level cross-sectional view of an electrochemical cell fabricated using a plurality of anodes fabricated in accordance with the present disclosure. Detailed description

[0021] In some aspects, the present disclosure relates to methods of forming anodes for one or more electrochemical devices using certain lamination techniques. Examples of electrochemical devices that may benefit from a lamination method for anode formation of the present disclosure include metal-based secondary batteries and supercapacitors, among others. In this context, "metal-based" means that the electrochemical device of interest has one or more anodes each comprising at least one metal layer that is the anode active material. Examples of metals that may be used for the metal layer include, but are not limited to, lithium, sodium, potassium, magnesium, and aluminum, or an alloy containing one or more of these metals, among others.As mentioned below, in certain embodiments, the lamination methods for anode formation of the present disclosure enable metal anodes, particularly alkali metal anodes, such as lithium metal anodes, to be fabricated in larger sizes than conventionally laminated anodes fabricated using the same anode active metal. These larger sizes result, for example, in higher capacity secondary batteries that overcome the limitations of conventional secondary batteries. As will be readily appreciated by those skilled in the art, the lamination techniques disclosed herein can be cost effective, and manufacturing cost is a particularly important parameter. for the manufacture of high-capacity secondary batteries required for high-energy demand applications, such as electric vehicles.

[0022] In some aspects, the present disclosure relates to anodes that include a current collector, a metal anode active layer on one or both sides of the current collector, and an electrically conductive coating (or simply "conductive coating") located between the current collector and each metal anode active layer. In some embodiments, the conductive coating is a conductive carbon-based coating, which may include one or more forms of conductive carbon, a binder, and optionally particles of one or more metals. In other embodiments, the conductive coating may include only particles of one or more metals and a binder. In some embodiments, the conductive coating enhances the attachment of the alkali metal layer to the current collector.For example, those skilled in the art will understand that, in conventionally produced laminated anodes, metallic lithium layers applied to copper current collectors do not always adhere well to the copper current collectors, causing them to delaminate from the copper current collectors upon handling. Use of a conductive coating of the present disclosure may prevent such delamination. A conductive coating of the present disclosure may also serve to maintain contact with the metallic lithium layer when the metallic lithium layer is primarily converted to a porous foam structure upon cycling.Use of a conductive coating of the present disclosure may also aid in locating metal foil sheets of anode active material on a current collector strip and / or enable new manufacturing techniques that take advantage of the excellent adhesive properties of certain embodiments of the conductive coating. The metal-based anodes of the present disclosure that include a conductive coating may be manufactured using any suitable method, such as any of the lamination methods for anode formation disclosed herein or any suitable conventional method.

[0023] In still further aspects, the present disclosure relates to methods of manufacturing an electrochemical device using any of the methods disclosed herein and / or using any of the anodes containing a conductive coating described herein and to electrochemical devices manufactured using a method of the present disclosure and / or using any of the anodes containing a conductive coating described herein. The foregoing and other aspects of the present disclosure are described in detail below.

[0024] Before proceeding to more detailed descriptions, it should be noted that throughout the present disclosure, the term "about," when used with a corresponding numerical value, refers to ±20% of the numerical value, typically ±10% of the numerical value, often ±5% of the numerical value, and more often ±2% of the numerical value. In some embodiments, the term "about" may mean the numerical value itself.It should also be noted that the term "side" when referring to an anode, layer, coating, foil, strip, tape or other component, or region thereof, of an anode of the present disclosure or to any other structure, or region thereof, used to form an anode of the present disclosure refers to the extent of the component or structure that extends between the edges of that component or structure in a direction perpendicular to the thickness of that component or structure. In other words, for purposes of the present invention, the "sides" of a component or structure are separated by the thickness of the component or structure.

[0025] Referring now to Figures 2, 3A, 3B and 4, and correspondingly noting that the first digit of each element number corresponds to the digit where that element is first shown, [Fig. 2] illustrates an exemplary anode formation lamination process 200 for forming anodes 300 (only one is shown detached) for one or more electrochemical devices (not shown), Figures 3A and 3B illustrate a strip anode precursor 304 and the anode 300 fabricated using the process, and [Fig. 4] illustrates an exemplary roll-to-roll (R2R) processing system 400 for performing various steps of the anode formation lamination process 200. The anode formation lamination process 200 may be used to form a plurality of anodes 300 that may all be the same size or may have different sizes. different.Each anode 300 includes a current collector 308 having an active material region 308A and an electrically conductive tab, or simply "tab," 308B formed as an extension of the active material region. The active material region 308A contains an anode active material 312 laminated to the anode 300 on one or both sides of the current collector 308, depending on the requirements of the anode design. The active material region 308A has a length, La, in a direction parallel to the direction, Dt, of extension of the tab 308B from the active material region, and the length La may be any suitable length, for example, from about 50 mm to about 800 mm, from about 100 mm to about 600 mm, or about 100 mm or more, for example, when the thickness, Tarn of the active material 312 is about 50 μm or less, in a range of about 15 μm to about 25 μm, or . of about 20 μm or less. The width, Wa, of the active material region 308A in a direction perpendicular to the length La may also be any suitable width, such as from about 10 mm to about 200 mm, from about 20 mm to about 150 mm, or less than about 120 mm when, for example, the thickness Tarn is about 50 μm or less, in a range of about 15 μm to about 25 μm, or about 20 μm or less. In some embodiments, the width Wa may be the maximum sheet width at a given thickness that can be formed from the selected anode active material using conventional sheet-forming techniques, including widths greater than 200 mm.For example, the current maximum width for a lithium foil is about 120 mm with a thickness of about 50 pm or less, but future technologies may allow for larger widths, and the techniques described in this paper can easily keep pace with these technologies.

[0026] The methods of the present disclosure enable lithium anodes, such as a lithium-based version of anode 300, to be produced with, for example, up to about 150 mm (Wa ([Fig.3A])) x about 600 mm (La ([Fig.3A])) surface dimensions or more when the thickness Tarn is about 50 µm or less, particularly if the industry designs ways of manufacturing lithium foils having widths greater than 120 mm, which is effectively the current limit. In one example, a conventional lamination process yielded Li / Cu / Li anodes of about 53 mm x 45 mm surface dimension at a lithium thickness of 20 µm, while a lamination process of the present disclosure, for example, lamination process 200 of [Fig. 2], yielded anodes 300 having an active zone length La of 550 mm and an active zone width of 107 mm at the same lithium thickness (Tarn).In proportion to the anode size, the capacity (Ah) and energy (Wh) of a cell will accordingly be much higher (e.g., up to 25x more, 50x more, or more) for secondary batteries assembled with the anodes 300 manufactured in accordance with the present disclosure, with or without optional conductive coating pieces 328 (see below). Lithium metal secondary batteries with a capacity greater than 100 Ah that are required for high energy demand applications, such as electric vehicles, can be constructed using the disclosed methodologies. As a comparative example, for the same number of stack layers, a 53 mm x 45 mm anode forms a ~4 Ah cell, while a 550 mm x 107 mm anode will form a ~100 Ah cell.Additionally, because larger cells require less packaging, the gravimetric and volumetric energy densities (Wh / Kg & Wh / L, respectively) of these batteries will also be higher. For example, in the previous example of ~4Ah cells versus ~100Ah, there will be a . increase in gravimetric energy density from about 400 Wh / kg to about 410 Wh / kg from the smallest cell to the largest cell.

[0027] In some embodiments, the anode 300 may include a conductive coating 316 between the anode active material 312 and the current collector 308 on either side of the current collector where the anode active material is present. It is generally desirable that the conductive coating 316, if present, and the anode active material 312 be approximately coextensive with the active material region 308A, i.e., have approximately the same length, Lee, and width, Wcc, as, respectively, the length La and width Wa of the corresponding active material region. As seen in [Fig. 3A], the anode 300 is shown removed from the strip anode precursor 304 by having been removed from a corresponding anode region 320(1) of the strip anode precursor. [Fig.3A] also shows two additional anode regions 320(2) and 320(3) on the strip anode precursor 304 that will yield two additional anodes (not shown) once removed from the strip anode precursor. Each anode region 320(1) to 320(3) includes an active region portion 320A(1) to 320A(3) and a tab portion 320B(1) to 320B(3). In [Fig.3A], the anode region 320(2) includes the active anode material and is ready for removal of the corresponding anode, while the anode region 320(3) does not yet include the active anode material. Examples of materials for each of current collector 308, anode active material 312, and conductive coating 316 are mentioned both above and below.

[0028] At block 205, the lamination method for forming anode 200 includes providing a current collector strip 324. In one embodiment and as illustrated in [Fig. 4], the current collector strip 324 may be provided as a ribbon 404 of current collector material suitable for the R2R processing system 400 of [Fig. 4]. In other embodiments, 324 may be provided in another form, such as in sheet form, whereby the current collector material is provided in individual sheets. The current collector strip 324 may be made of any suitable electrically conductive material, such as a metal, for example, copper, nickel, titanium, or stainless steel, among others, or any suitable metal alloy. Basically, there is no limitation with respect to the type of material used for the current collector strip.The current collector strip 324 may have any variety of shapes, such as a solid sheet, a perforated sheet, a woven mesh, or an expanded mesh, among others. Basically, there is no limitation regarding the shape of the current collector strip 324. Any mesh or other open structure may have a . percentage open area to total area in a range of about 5% to about 95%. The perforated mesh, if used, may be manufactured by a variety of methods, including, but not limited to, conventional perforation, rotary die-cutting, electroforming, photoetching, and laser cutting, among others. In some embodiments, the current collector strip 324 has a width, Ww, in a range of about 20 mm to about 200 mm, in a range of about 120 mm to about 200 mm, in a range of about 150 mm to about 300 mm, or greater, particularly when the thickness of the anode active material Tarn is about 50 μm or less and the active material is an alkali metal, such as lithium.The length of the current collector strip 324 may be any suitable length to enable implementation of an anode forming lamination process of the present disclosure, such as the anode forming lamination process 200 of [Fig. 2] in a ribbon-based process or a sheet-based process.

[0029] The tabs 308B of the current collectors 308 of the anodes 300 may be formed from bare regions 304A of the current collector strip 324, i.e., regions of the current collector strip that do not contain any anode active material, and if the optional conductive coating 316 is used, that also do not contain any conductive coating material. Therefore, this requires that the tab portions 320B(1) to 320B(3) of the anode regions 320 of the strip anode precursor 304 be bare, as mentioned below.

[0030] At optional block 210, an optional piece of conductive coating 328 is applied to one or each side of current collector strip 324 depending, for example, on whether finished anode 300 has anode active material on one or both sides of the current collector strip. In [Fig. 3A], only one piece of conductive coating 328 is shown, but in this example, a similar piece of conductive coating is also on the opposite side of the current collector strip 324. If provided, the conductive coating is provided in pieces of conductive coating 328 to provide inter-piece regions 304A which are bare portions of the current collector strip 324 in which the tab portions 320B of the anode regions 320 are / will be located and from which the tabs 308B of the anode 300 are / will be formed.Each inter-piece region 304A may have a gap width, Wg, greater than or equal to the length, Lt, of the corresponding tab 308B on the respective anode 300. In some embodiments, the gap width Wg may be in a range of about 10 mm to about 30 mm based on the length Lt of the tabs 308B being of the same or similar dimension. In other embodiments, the gap width Wg of each inter-piece region 304A may be greater. to about 30 mm or less than about 10 mm to suit a particular anode design.

[0031] When conductive coating pieces 328 are provided on both sides of the current collector strip 324, the conductive coating pieces for the same anode 300 are aligned with each other such that the conductive coating pieces and the inter-piece regions 304A are in the same locations as each other along the length of the current collector strip 324. In some embodiments, the width, Wccp, of each conductive coating piece 328 is approximately equal to the width Wa of the active material region 308A of the anode 300 to minimize waste.In some embodiments, the width Wccp of each piece of conductive coating 328 is greater than the width Wa of the active material region 308A by about 1 mm to about 3 mm, or more, on each side of the active material region 308A to ensure that when the anodes 300 are removed from the strip anode precursor 304, conductive material is present at the cut edges of the anodes.

[0032] In some embodiments, the width, Wccp, of each piece of conductive coating 328 is approximately equal to the width Ww of the current collector strip 324, particularly when the method 200 is used to create the anodes 300 from a single line of anode regions 320. In some embodiments, the width Wccp of each piece of conductive coating 328 is made to be less than about 95% of the width of the current collector strip 324 so as to leave sufficient current collector strip intact to facilitate handling of the scrap. For example, with sufficient current collector strip 324 remaining after removal of the anodes 300 in an R2R system, such as the R2R system 400 of [Fig. 4], the scrap may be wound onto a scrap collection roll (not shown).In some embodiments, the width Wccp of each piece of conductive coating 328 and / or the width Waamp of the corresponding piece of anode active material 336 are made to be less than 100% of the width Ww of the current collector strip 324, such as, for example, about 0.9 Ww < Wccp and / or Waamp < Ww, about 0.95 Ww < Wccp and / or Waamp < Ww, or about 0.98 Ww < Wccp and / or Waamp < Ww, among others. In some embodiments, the length, Lccp, of each piece of current collector 328 is made to be approximately equal to the length La of the active material region 308A of the anode 300 to minimize waste. In some embodiments, the length Lccp of each piece of conductive coating 328 is greater than the length La of the active material region 308A by about 1 mm to about 3 mm on each side of the active material region 308A to ensure that when the anodes 300 are removed from the . strip anode precursor 304, conductive material will be present at the cut edges of the anodes. Along the edge of the piece of conductive coating 328 where the tab 308B is located, the conductive coating should typically be flush with or extend at most about 1 mm beyond the piece of anode active material 336. Typically, it is preferable that the piece of conductive coating 328 and the piece of anode active material 336 extend no more than about 1.5 mm onto the tab 308B. Otherwise, this “excess” material may interfere with the tab welding process.

[0033] Each piece of conductive coating 328 may act as a primer to the corresponding piece of anode active material 336 to help improve adhesion therebetween while maintaining low contact resistance between the anode active material 312 and the current collector 308 in the final anode 300. If provided, each piece of conductive coating 328 may be made of any suitable conductive material, such as a conductive carbon material that includes one or more types of conductive carbon particles and a suitable binder for binding the particles to each other and to the current collector strip 324. In other embodiments, the conductive carbon particles may be augmented with metal particles, while in still other embodiments, only metal particles may be used with a suitable binder.

[0034] If a conductive carbon material is used, it may be provided in the form of a slurry prepared by mixing a conductive carbon and a binder material in an aqueous or organic solvent medium that is ultimately dried after being applied to the current collector strip 324. Examples of conductive carbon material that may be used include carbon black, graphite, graphene, carbon fibers, carbon nanotubes, or a mixture thereof. Metals, such as silver, in powder form may also be mixed with the conductive carbon to improve electrical conductivity. Examples of binder material include, but are not limited to, PVDF (polyvinylidene fluoride), PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene), CMC (carboxymethylcellulose), and SBR (styrene-butadiene rubber), and a mixture thereof.

[0035] As noted above, the binder in the conductive coating pieces 328 can help the anode active material pieces 336 adhere well to the current collector strip 324 and prevents delamination of the anode active material from the current collector strip and the current collector 308 during handling and use. The conductive material(s) in the conductive coating help maintain low contact resistance between the active material anode 312 and current collector 308 in the finished anode 300, which, along with improved adhesion, helps to improve cell cycle performance in secondary batteries manufactured using anodes incorporating such conductive material or materials.

[0036] The thickness of each piece of conductive coating 328 may be, for example, in a range of about 0.1 μm to about 5 μm, in a range of about 0.5 μm to about 2 μm, and about 1 μm, among other ranges and values. In some embodiments, if the surface roughness (Ra, arithmetic mean roughness) of the anode active material is X μm, then the thickness of the coating may be in a range of about 0.2X μm to about 2X μm. Current evidence demonstrates that, in some embodiments (including embodiments in which lithium foil is used for the pieces of anode active material 336), a thickness of about 1 μm for each piece of conductive coating 328 may be optimal based on the following considerations. The pieces of conductive coating 328 should be sufficiently large to improve adhesion and conductivity.However, thicker coatings can generate side reactions and add unnecessary weight and volume to a cell. Additionally, there may be a minimum thickness that accommodates variation in the average surface roughness of the anode active material (e.g., lithium). The relationship may be directly or inversely proportional depending on several factors. For example, in the context of lithium, metallic lithium deforms easily, and a lithium foil with a higher roughness can easily adhere to, for example, a copper surface, and a thin conductive coating may be sufficient.However, this relationship can be further complicated by any passivation layer present on the lithium foil surface, as a pristine lithium surface may bond perfectly to the copper surface, but most lithium foils have a passivation surface layer with different chemistry and thickness values depending on the specific production process of a given supplier. Therefore, there can be variability regarding the optimal thickness depending on the particular facts involved.

[0037] In some embodiments, the surface loading of the conductive coating material in each piece of conductive coating 328 may be in a range of about 0.1 g / m2 to about 2 g / m2 and, in some embodiments, about 0.5 g / m2. In some embodiments, the surface resistance of each piece of conductive coating 328 may be less than about 30 ohms / square for a coating thickness of about 1 μm, and the surface resistivity may be less than about 3 x 103 ohm-cm. Generally, the resistance units surface resistance are ohms / square, and the surface resistance depends on the thickness of each piece of conductive coating 328, and the thicker the piece of conductive coating, the lower the resistance. Therefore, for thicknesses other than about 1 μm, the surface resistance will be other than 30 ohms / square. In some embodiments, the amount of conductive material (e.g., a conductive carbon, a conductive metal, or a combination thereof) in the conductive coating material may be in a range of about 5 wt% to about 95 wt% or in a range of about 70 wt% to about 90 wt%.

[0038] As an example of an advantage to using the conductive coating pieces 328, when the anode active material is lithium and the current collector strip 324 is copper, fresh lithium typically adheres well to the copper surface. However, the passivation layer that is typically present on the surface of conventional lithium foils inhibits its adhesion to copper. The composition of the passivation layer depends on the atmosphere to which the lithium foil was initially exposed during manufacture and is generally made of salts, such as lithium carbonate, lithium hydroxide, lithium oxide, and lithium nitride. In addition, the surface of the lithium foil may also have residual lubricants from the rolling process used to form the lithium foil.The presence of a passivation layer and / or oil residue on the surface prevents the lithium foil from adhering well to the copper during lamination. The provision of the conductive coating pieces 328 helps overcome this problem by providing a layer that adheres well to the current collector strip 324 and to which the anode active material pieces 336 adhere well.

[0039] For example, a peel test was applied to samples of lithium foil (anode active material) pressure-laminated onto copper foil (current collector) - one with the lithium foil applied directly to the copper foil and the other with a conductive carbon coating present between the lithium foil and the copper foil. A piece of SCOTCH® tape (available from 3M Corporation, St. Paul, Minnesota) was gently pressed onto the lithium foil of each sample and then slowly peeled off.Although the lamination conditions were the same between the two samples, except for the presence of the conductive coating in one of the samples, the lithium foil that was laminated directly onto the copper foil peeled off the copper foil with the tape, whereas the lithium foil laminated on the conductive carbon coating did not peel off with the tape and remained laminated on the conductive carbon coating and the copper foil under the conductive carbon coating. It should be noted that a pressure-sensitive tape other than Scotch® tape can be used. If the lithium foil adheres well to the copper foil, then the peel strength is typically greater than about 200 N / m.

[0040] To apply the optional conductive coating pieces 328 to the current collector strip 324, the exemplary R2R system 400 may include coating application equipment 408 suitable for the type of conductive coating material in question. For example, the coating application equipment 408 may include one or more coating applicators 408A(1) and 408A(2) which may be knife-type applicators, spray applicators, or roller applicators, among others. Examples of coating methods that may be used include flat die casting, strip casting, gravure printing, comma, spray coating, and dip coating, among others. Essentially, there are no limitations with respect to the manner in which the conductive coating pieces 328 may be applied.The coating application equipment 408 may also include one or more contour shaping devices 408B(l) and 408B(2), such as an open mask or a silk screen, among others, to ensure that the conductive coating pieces are of the desired size. Those skilled in the art will readily understand how to apply the optional conductive coating pieces 328 to the current collector strip 324 at the appropriate locations on the strip anode precursor 304 and the appropriate coating application equipment 408 necessary for such application, such that detailed descriptions of each are not necessary for those skilled in the art to practice the present inventions to their fullest extent without undue experimentation.

[0041] At block 215, a metal foil 332 is laminated to one or each side of the current collector strip 324 as a corresponding piece of anode active material 336 (only one is shown, but in this example another piece of anode active material is present on the opposite side of the current collector strip). Laminating the metal foil 332 may first include engaging the metal foil 332 with the current collector strip 324, with or without the conductive coating pieces 328 depending on whether they are used in a particular application. Engaging the metal foil 332 may be accomplished in any suitable manner, such as, for example, via transfer from a temporary holding substrate or via a pick and place system, among others.In some embodiments, the metal foil 332 may be pressed into firm engagement with the current collector strip 324 or, if present, with each corresponding piece of conductive coating 328. Such pressing may be performed in any suitable manner, such as, for example, using a roller press or a stationary press, among others. In some embodiments, the lamination of the metal foil 332 may be performed using a rolling mill or a calendering machine, with the lamination pressure being determined by adjusting the gap between the rollers. In some embodiments, the pressure applied by the rollers should not significantly deform the metal foil 332, i.e., there should be a negligible reduction in thickness or a negligible increase in the width and / or length of the lithium foil.For example, when a piece of conductive coating 328 is present, it is typically desirable that the metal foil 332 in the corresponding piece of anode active material 336 remains approximately within the footprint of the underlying piece of conductive coating. In some embodiments, it is desirable that the reduction in thickness of the metal foil 332 be less than about 10% of the original thickness of the metal foil and that the increase in length and / or width of the metal foil be less than about 2%. Essentially, there is no limitation as to how the metal foil 332 can be pressed onto the strip anode precursor 304.

[0042] The metal foil 332 may have a thickness in a range of about 15 µm to about 25 µm in some embodiments, about 20 µm in some embodiments, in a range of about 10 µm to about 50 µm in some embodiments, and in a range of about 1 µm to about 100 µm in some embodiments, among other ranges and values. These thicknesses may be particularly applicable to lithium-containing alkali metal foils, including pure lithium, in general, and to foils based on one or more other metals. Current evidence demonstrates that a thickness of about 20 μm for 332 metal foil, especially lithium metal foil, although increasing the thickness of an electrochemical cell fabricated using 300 anodes, may be an optimal compromise between various factors, including cycle life, workability, cost, weight, and plating, among others.In some embodiments, the thickness of the current collector strip 324 may be in a range of about 4 μm to 10 μm and, in some embodiments, about 6 μm, including the case where the current collector strip is copper foil, among other ranges and values. Current evidence demonstrates that a thickness of 6 μm for the current collector may be an optimal compromise between, for example, weight, strength, energy density, lamination complexity, cost, and thickness, among others.

[0043] In some embodiments, the metal foil 332 may be pre-sized to be approximately equal to the size of the active region portions 320A(1) to 320A(3) of the anode regions 320(1) to 320(3) or the size of the corresponding piece of conductive coating 328, or both. Such sizing could be used, for example, in a transfer process from a temporary substrate or in a pick and place process, such as a pick and place process using a suitable light vacuum. In some embodiments, the metal foil 332 may be provided as a continuous sheet or a continuous ribbon.For example, if the conductive coating pieces 328 are used and they provide significant adhesion for the metal foil relative to the bare portions of the current collector strip 324, then the anode active material pieces 336 can be formed by pressing the continuous foil or continuous tape onto the current collector strip and removing the portions of the metal foil 332 from the previously bare portions of the current collector strip where the metal foil does not adhere well. In some embodiments, the width, Waamp, of each anode active material piece 336 is approximately equal to the width Wa of the active material region 308A of the anode 300 to minimize waste.In some embodiments, the width Waamp of each piece of anode active material 336 is greater than the width Wa of the active material region 308A by about 1 mm to about 3 mm on each side of the active material region 308A to ensure that when the anodes 300 are removed from the strip anode precursor 304, conductive material will be present at the cut edges of the anodes.

[0044] In some embodiments, if conductive coating pieces 328 are used and the conductive coating material used provides the conductive coating pieces with suitable characteristics, then the method 200 may include, in an optional sub-block 215A, using the conductive coating pieces to align the sheets of metal foil 332 with the conductive coating pieces. For example, if the conductive coating piece 328 provides a machine-detectable contrast, such as an optical contrast, between the conductive coating pieces and the underlying current collector strip 324, then a suitable detection system may be provided to detect the contrast and provide location information to a control system that controls the alignment of the sheets of metal foil 332 with the conductive coating pieces.An example of a detection system is a machine vision system that can detect and locate one or more edges of each piece of conductive coating 328.

[0045] Referring to [Fig. 4] and the exemplary R2R system 400, the R2R system may include a lamination region 412 where the metal foil 332 (only some are marked in [Fig. 4]) is engaged with and laminated to the current collector strip 324. As noted above, the lamination region 412 may take any of a wide variety of shapes depending, for example, on how the metal foil 332 is delivered to the current collector strip 324, whether or not pieces of conductive coating 328 are used, and how the metal foil is pressed onto the current collector strip. In the embodiment illustrated in [Fig. 4], the metal foil 332 is delivered as individual sheets 416 (only some are marked in [Fig.4]) on a pair of temporary support tapes 420(1) and 420(2) - one for each side of the current collector strip tape 404 - which relatively loosely holds the sheets before they are laminated to the current collector strip tape. The disclosed embodiment also includes a roller press 424 which presses the sheets 416 into firm engagement with the current collector strip tape 404 to form the anode active material pieces 336.

[0046] In this embodiment, the sheets 416 are delivered to the current collector strip ribbon 404 using a pair of transfer rollers 428(1) and 428(2) which may, for example, apply a relatively small amount of pressure to effect transfer of the sheets to the current collector strip ribbon. Due to greater adhesion between the sheets 416 with the current collector strip tape 404, particularly when the conductive coating pieces 328 are present, than between the sheets and the temporary backing tape 420(1) and 420(2), the temporary backing tapes can be easily peeled off the anode active material pieces 336 that are now part of the strip anode precursor 304. In some embodiments, the spacing between the sheets 416 on the temporary backing tapes 420(1) and 420(2) precisely matches the inter-piece regions 304A.In other embodiments, the spacing between the sheets 416 on the temporary carrier tapes 420(1) and 420(2) may not correspond to the inter-piece regions 304A. In some embodiments, when the spacing between the sheets 416 on the temporary carrier tapes 420(1) and 420(2) precisely corresponds to the inter-piece regions 304A, all of the temporary carrier tapes 420(1) and 420(2) and the current collector strip tape 404 may be passed through the roller press 424. In this case, the transfer rollers 428(1) and 428(2) may be omitted.

[0047] Referring again to [Fig. 4], if the conductive coating pieces 328 are used, the exemplary R2R system 400 may optionally include a system alignment system 432 that uses the conductive coating pieces to precisely align the sheets 416 with corresponding respective ones of the conductive coating pieces. This alignment places each sheet 416 in precise and proper alignment with a corresponding one of the conductive coating pieces 328 before that sheet of anode active material is firmly laminated by the roller press 424 to create the corresponding piece of anode active material 336. When the conductive coating pieces 328 comprise a visually highly contrasting material, such as a conductive carbon coating, compared to the bare material of the current collector strip 324, the alignment system 432 may comprise one or more optical sensors, here two optical sensors 432A(1) and 432A(2), for detecting and locating at least one edge of each piece of conductive coating.The alignment system 432 may also include one or more controllers 432B (only one shown) and one or more actuators, such as stepper motors (not shown), which the controller controls to accurately advance each of the temporary carrier strips 420(1) and 420(2). The controller 432B may be programmed to use location information about one or more edges from the optical sensors 432A(1) and 432A(2) and position information for the temporary carrier strips 420(1) and 420(2) to accurately control the alignments of the sheets 416 with corresponding alignments of the conductive coating pieces 324.Those skilled in the art will understand how to implement various types of alignment systems that can utilize the conductive coating pieces 328 to assist in aligning the sheets 416 with the conductive coating pieces 328 without undue experimentation.

[0048] The exemplary method 200 further includes a block 220 at which the anodes 300 are formed from the strip anode precursor 304. The anodes may be formed from the strip anode precursor 304 in any suitable manner, such as by swaging, twisting, or otherwise cutting the strip anode precursor 304 at the anode regions, e.g., anode regions 320(1) to 320(3) to define and release the resulting anodes 300 therefrom. In this regard, [Fig. 4] illustrates an exemplary R2R system 400 including anode forming equipment 436, which may include any suitable automated swaging, twisting, or other cutting tool, which may be configured to form one or more of the anodes 300 at a time. One skilled in the art will readily understand how to implement the appropriate anode forming equipment 436 without the need for undue experimentation.The formed 300 anodes can now be ready for use in the next step of . manufacturing one or more electrochemical devices (not shown) using the anodes 300 thus formed.

[0049] Figures 5A, 5B, 5C, 5D, and 5E illustrate some examples of alternative arrangements of anode regions and pieces of anode active material (and underlying conductive coating pieces, if any) on various strip anode precursors that may be used in place of the arrangements of anode regions 320 and pieces of anode active material 336 (and if any, pieces of conductive coating 328) on the strip anode precursor 304 of [Fig. 3A]. It should be noted that alternatives to the arrangements illustrated with respect to the strip anode precursor 304 of [Fig. 3A] are not limited to the alternative arrangements of Figures 5A-5E; rather, they are example arrangements provided to illustrate the flexibility of the anode formation methods according to the present disclosure. In describing Figures 5A to 5E below, no reference is made to the pieces of conductive coating to simplify the explanation.However, as just seen, pieces of conductive coating may indeed be present beneath the corresponding pieces of anode active material, for example in a manner discussed above in connection with Figures 2-4. It should also be noted that the alternative arrangements of Figures 5A-5E are described as if the pieces of anode active material were located only on the obverse side of the strip anode precursors, as seen in the figures. While this may be the case, the reverse side of the strip anode precursors may also have corresponding pieces of anode active material (and optionally pieces of conductive coating) in alignment with the pieces of anode active material on the obverse side of the strip anode precursors.It should further be noted that, aside from the different arrangements of the anode regions and pieces of anode active material, such as materials, thicknesses, surface dimensions, and methods of creation, among others, the anode regions of Figures 5A-5E may be the same or similar to anode regions described elsewhere in this disclosure, for example, compared to anode regions 320(1)-320(3) of [Fig.3A], .

[0050] [Fig.5A] illustrates an exemplary strip anode precursor 500 in which the pieces of anode active material 504(1) to 504(5) (solid lines) are provided in a single line on the underlying current collector strip 508. In this example, each piece of anode active material 504(1) to 504(5) is provided to form a single anode region 512(1) to 512(5) (dotted lines) which will eventually be removed from the strip anode precursor 500 to form a corresponding anode (not shown, but similar to the anode 300 of Figs. 3A and 3B).

[0051] As can be seen by comparing Figures 5A to 3A, a difference between the strip anode precursor 500 of [Fig. 5A] and the strip anode precursor 304 of [Fig. 3A] is that the tab portions 512A, here 512A(2) to 512A(5), of the immediately adjacent pairs of anode regions 512(2) to 512(5) are located in the same inter-piece regions 516, here 516(1) and 516(2). This arrangement allows for reduced waste of the current collector strip 508, because the inter-piece regions 520, here 520(1) and 520(2), can be made smaller than the inter-piece regions 516 which contain the pairs of tab portions 512A(2) to 512A(5).

[0052] Generally, [Fig. 5B] is similar to [Fig. 5A], except that the feature of minimizing the size of the inter-piece regions 520 ([Fig. 5A]) is taken to an extreme in [Fig. 5B] by eliminating these inter-piece regions altogether. In this manner, the pairs of anode active material pieces 504(1) to 504(4) on opposite sides of the inter-piece regions 520 ([Fig. 5A]) are, in [Fig. 5B], effectively joined into a single anode active material piece 524, here 524(1) and 524(2), which, in this example, is approximately twice the size of each of the anode active material pieces 504(1) to 504(5) of [Fig. 5A]. With this configuration, each piece of anode active material 524 of [Fig.5B] is provided to form two anode regions 528, here anode regions 528(1) and 528(2) at piece of anode active material 524(1) and anode regions 528(3) and 528(4) at piece of anode active material 524(2).Depending on the processing limitations of the anode active material used versus the size of the anode regions needed, the configuration of [Fig. 5B] may not be feasible. For example, if the anode active material is lithium, the processing limitations may limit the length of the anode active material pieces, such as the anode active material pieces 504 and 524 of Figures 5A and 5B, respectively, that can be fabricated. In such cases, it may be necessary to use a different configuration in which there is a 1:1 correspondence between the anode active material pieces and the number of anode regions prepared from those anode active pieces, such as either of the configurations shown in Figures 3A and 5A, among others.

[0053] Figures 5C, 5D and 5E, respectively, illustrate multi-line variants 530, 550 and 570 of the example configurations shown in Figures 3A, 5A and 5B. In reviewing the multi-line variants 530, 550 and 570 of Figures 5C-5E, the reader may refer to Figures 3A, 5A and 5B and the corresponding description for further information on the corresponding single-line configuration, as each of these multi-line variants may be realized by starting with a larger (e.g., wider) current collector strip, herein 534, 554 and 574, respectively, and repeating the corresponding single-line pattern multiple times over such a larger current collector strip. It should be noted that although each of the variants 530, 550, and 570 of Figures 5C, 5D, and 5E shows two lines 538(1) and 538(2), 558(1) and 558(2), and 578(1) and 578(2) of anode active material pieces 542 (here, 542(1) to 542(6)), 562 (here, 562(1) to 562(10)), and 582 (here, 582(1) and 582(4)), in other embodiments, a larger number of lines may be provided. Generally, the only limitations on the number of 538, 558, and 578 lines implemented are the availability of sufficiently large 534, 554, and 574 current collector strips and the ability to manufacture the corresponding manufacturing equipment.It should also be noted that, like other embodiments disclosed herein, each of the current collector strips 534, 554, and 574 may be, for example, sheet-like or ribbon-like depending on the type of processing equipment used. For example, ribbon-like current collector strips readily lend themselves to R2R processing, such as in an R2R system similar to the R2R system 400 of [Fig. 4].

[0054] It should be noted that all embodiments shown in Figures 3A-5E show all anode regions and, accordingly, the pieces of anode active material, any pieces of conductive coating, if any, and the anodes formed therefrom, as being of uniform size in each figure. However, while this would be typical for a production run of electrochemical cells of a common size, this need not be the case. For example, certain embodiments of anode formation methods of the present disclosure can be adjusted to make anodes of different sizes on the same strip anode precursor.

[0055] [Fig. 6] is a graph of discharge capacity versus number of cycles comparing the cycling life performance of lithium-copper (Li / Cu) anodes (Li at 20 µm thickness, double-sided on Cu, Cu at 8 µm thickness, 1 µm thick coating composed of about 70% to about 90% carbon black and PVDF) with or without a conductive coating of the present disclosure. To generate the data for this graph, a cycling life test was conducted in multi-layer pouch cells constructed with nickel-manganese-cobalt (NMC) oxide-based cathodes and polyolefin-based microporous separators. The pores of the cathode and separator are filled with a conductive Li+ liquid electrolyte. The electrolyte typically contains a lithium salt, such as LiPF6 or LiFSI dissolved in a carbonate or ether solvent.The cells were cycled between 2.5 V and 4.3 V at a charge-discharge rate of C / 5-1C.

[0056] As shown in [Fig.6], the inclusion of a conductive coating of the present disclosure on the copper current collector was found to improve the cycling life performance of cells with a lithium anode. With increasing cycle number, the dense lithium gradually became a more porous structure, and the conductive coating helped maintain good electrical contact between the porous lithium and the copper current collector substrate. This further led to a more uniform current density distribution and uniform plating / extraction of lithium and, therefore, improved cycling life performance.Although the initial specific surface impedance (ASI) of the cells fabricated with conductive coatings on the copper current collector was higher than that of the cells containing the uncoated copper current collector (~38 ohm-cm2 with coating vs. ~28 ohm-cm2 without coating), as the number of cycles of the cells increased, the difference gradually decreased, and after 500 cycles, the relative ASI of the cells fabricated with the conductive coating was found to be lower than that of the cells containing the uncoated copper current collector (~85 ohm-cm2 with coating vs. ~92 ohm-cm2 without coating).

[0057] It should be noted that when an electrically conductive coating of the present disclosure, such as the optional conductive coating 316 of the exemplary anode 300 of [Fig. 3A], is present in an anode, the anode need not be fabricated using a lamination method of the present disclosure. For example, the anode active material, which is equivalent to the anode active material 312 of the anode 300, may be applied using another method, such as vapor deposition, among other potential techniques that are or may be under development.

[0058] [Fig. 7] illustrates an exemplary secondary battery 700 manufactured in accordance with the present disclosure. In particular, the exemplary battery 700 includes a stacked roll 704 that includes a plurality of anodes 708 that either include an electrically conductive coating (not shown) of the present disclosure, such as the conductive coating 316 of [Fig. 3A], or are manufactured using a lamination method of the present disclosure, such as the lamination method 200 of [Fig. 2], or both.The novelty of the exemplary secondary battery 700 may arise from the novelty of the anodes 708 themselves in terms of having a single layer of conductive coating (not shown, but see, for example, conductive coating 316 of Figures 3A and 3B) contained therein and / or by their areal dimension greater than the areal dimension of conventionally manufactured laminated anodes, as well as by the performances. improved cycle life and / or the resulting higher gravimetric and volumetric energy densities, compared to conventionally designed and manufactured anodes. The stacked roll 704 also includes a plurality of separator layers 716 and a plurality of cathodes 720 electrically separated from the anodes 708 by the separator layers.

[0059] In this example, the stacked roll 704 is sealed inside an envelope, here a pouch-like envelope 712, with a suitable electrolyte (not shown, but present in at least the separator layers 716 (not all labeled), which may be considered part of a polymer electrolyte if a solid or gel-like electrolyte is used). In other embodiments, the pouch-like envelope 712 may be replaced with an envelope of a different type, such as a rigid-walled housing, among others. Fundamentally, the type of envelope is important only to the extent that it provides the required functionality, including providing a sealed volume to contain the stacked roll 704 and the electrolyte. One skilled in the art is well aware of the techniques and materials for constructing the pouch-like envelope 712 or another type of envelope that a particular design may include.Therefore, further details of the casing 712 are not necessary herein for those skilled in the art to illustrate by example the secondary battery 700 without undue experimentation.

[0060] As discussed above, each anode 708 may comprise any suitable anode active metal, such as lithium, sodium, potassium, magnesium, or aluminum, or any suitable combination thereof, just as with the exemplary anode 300 discussed above. Depending on the battery type, e.g., lithium metal, sodium metal, lithium air, lithium sulfur, etc., each cathode comprises a suitable cathode active material. In one or more embodiments, the cathode has the general formula LixMyOz, where M is a transition metal such as Co, Mn, Ni, V, Fe, or Cr.

[0061] In one or more embodiments, each cathode 720 may comprise a spinel or layered oxide material selected from the group consisting of LiCoO2, Li(Nii / 3Mni / 3Coi / 3)O2, Li(Nio,8Co0,i5Alo,o5)02, LiMn2O4, Li(Mni>5Ni 0,5)204 or lithium-rich versions thereof. In one or more embodiments, each cathode 720 may have the general formula LixMyPOz, wherein M is a transition metal such as Co, Mn, Ni, V, Fe, or Cr. In one or more embodiments, each cathode 720 may be a phosphate material selected from the group consisting of LiFePO4, LiNiPO4, LiCoPO4, or LiMnPO4. In one or more embodiments, each cathode 720 may include a porous coating comprising a cathode active material powder, a polymer binder, such than a PVDF, and a conductive diluent such as a carbon black. In one or more embodiments, each cathode 720 may comprise a porous coating on an aluminum foil. In one or more embodiments, each cathode 720 may comprise a lithium cobalt oxide (or lithium cobaltate), a lithium manganese oxide (also known as lithium spinel or lithium manganate), a lithium iron phosphate, as well as a lithium nickel manganese cobalt oxide (or NMC) and / or a lithium nickel cobalt aluminum oxide (or NCA).In one or more embodiments, each cathode 720 may include a nanoscale and nanostructured sulfur-based composite, such as a sulfur-impregnated core-shell hierarchical porous carbon (HPC) composite, a sulfur / graphene nanosheet (GNS) composite, a sulfur@rGO (reduced graphene oxide) composite having a saccule-like structure, and a CS@PANi (polyaniline) composite with a structured spherical polymer network, among others. In one or more embodiments, each cathode 720 may include carbon layers sandwiched around a current collector and then covered with a polymer film, such as a PTFE film. The carbon layers may contain a metal catalyst that improves oxygen reduction kinetics and increases the specific capacity of the cathode 720.Examples of metal catalysts include, but are not limited to, manganese, cobalt, ruthenium, platinum, silver, and mixtures thereof.

[0062] In one or more embodiments, when the electrolyte is a liquid, each separator layer 716 may be made of one or more materials, at least one of which is a dielectric. For example, in one or more embodiments, each separator layer 716 may be made of a polypropylene or a polyethylene or any suitable combination (e.g., blend, layers, coating, etc.) thereof. Those skilled in the art will understand the variety of materials and constructions that may be used to fabricate each separator layer 716.

[0063] With respect to the electrolyte, in one example, the secondary battery 700 is a lithium metal battery, meaning that the anodes 708 comprise lithium metal on / from which lithium ions are deposited and extracted during, respectively, the charge and discharge cycles. Correspondingly, the electrolyte contains lithium ions (not shown) that circulate between the anodes and cathodes 720 within the stacked roll 704 during the charge and discharge cycles. Therefore, in this example, the electrolyte comprises one or more lithium-based salts in a suitable form, such as in a solution, a eutectic mixture, or a molten form, among others. In some embodiments, the electrolyte may contain one or more solvents, one or more performance and / or property enhancing additives, and / or one or more polymers, among others. The electrolyte may be in any suitable state of matter, such as a liquid, gel, or solid state. The composition of the electrolyte, whether for a lithium metal-based version of the secondary battery 700 or a version based on another type of metal (e.g., sodium, potassium, aluminum, magnesium, among others), may be any composition suitable for the particular application in question and may be determined by the designer of the particular instantiations of the secondary battery.

[0064] Examples of salts that may be used in the electrolyte include, but are not limited to, LiFSI, LiTFSI and lithium fluorosulfonyl(trifluoromethylsulfonyl)imide (LiFTFSI), LiPF6, LiAsF6, LiBF4, LiBOB and Li triflate, and any combination thereof, among others.In one or more embodiments, two or more salts may be combined in a eutectic mixture, such as a eutectic mixture that includes a first salt, Xi+Yi, and a second salt, X2+Y2, wherein each of Xl+ and X2+ is an alkali metal cation and Xl+ is different from X2+, and each of Yf and Y2 is a sulfonimide anion and Yf is different from Y2. In one or more embodiments, Yf and Y2 may be selected from the group consisting of FSO2N SO2F (FSI) and FSO2N SO2CF3 (FTFSI) and / or X / and X2+ may be selected from the group consisting of Li+, Na+, K+, Rb+, and Cs+. In one or more embodiments, the eutectic mixture may further include a third salt, X3+Y3, wherein X3+ is different from X / and X2+.In one or more embodiments, Yi, Y2, and Y3 may be selected from the group consisting of FSO2N SO2F (FSI) and FSO2N SO2CF3 (FTFSI) and / or X / , X2+, and X3+ may be selected from the group consisting of Li+, Na+, K+, Rb+, and Cs+.

[0065] In one or more embodiments, the electrolyte may comprise an imide salt, e.g., lithium bisfluorosulfonylimide (LiN(FSO2)2, and a perchlorate salt in an aprotic solvent. Other lithium imide salts having a fluorosulfonyl group (FSO2), e.g., LiN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(FSO2)(C2F5SO2), may be used instead of or in combination with lithium bisfluorosulfonylimide (LiN(FSO2)2. In one or more embodiments, the perchlorate salt may comprise LiClO4. In one or more embodiments, the perchlorate salt has a concentration between 0.05 mole / liter and 0.50 mole / liter of the organic solvent. In one or more embodiments, the perchlorate salt is selected from the group consisting of LiClO4, Ca(C104)2, Sr(ClO4 )2, Mg(C104)2, Ba(C104)2, and any combination or mixture of these.

[0066] In one or more embodiments, the electrolyte may comprise a glyme of the formula Ri-(O-CH2-CH2)nO-R2, wherein n = 1 to 4 and at least one of Ri and R2 is a hydrocarbon side chain containing at least 2 carbon atoms. In one or more embodiments, such an electrolyte may further comprise a diluent selected from the group consisting of a fluorinated glyme and a fluorinated ether.Fluorinated diluent can allow the use of more stable longer side chain glyme-based solvents, such as DEE (1,2-diethoxyethane or ethylene glycol diethyl ether), DPE (1,2-dipropoxyethane or ethylene glycol dipropyl ether), DBE (1,2-dibutoxyethane or ethylene glycol dibutyl ether), diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, triethylene glycol diethyl ether, triethylene glycol dipropyl ether, triethylene glycol dibutyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dipropyl ether, tetraethylene glycol dibutyl ether, etc. In one or more embodiments, the diluent may be fluorinated ether 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), or fluorinated ether bis(2,2,2-trifluoroethyl) ether (BTFE).In one or more embodiments, the diluent may comprise suitable hydrocarbon molecules containing at least one oxygen (-O-) bond and at least one fluorine (-F) substitution. In a specific example, DEE and TFE are combined with each other. In one or more embodiments, the solvent:diluent ratio of an electrolyte made in accordance with this paragraph may be in a range of about 10:90 to 100:0. In one or more embodiments, it may be desirable for the solvent:diluent ratio to be in a range of about 40:60 to about 90:10, and in one or more embodiments, it may be desirable for the solvent:diluent ratio to be in a range of about 60:40 to about 80:20.

[0067] In one or more embodiments, the electrolyte may be a free solvent-free liquid lithium sulfonimide salt composition consisting essentially of an adduct of molecules of a lithium sulfonimide salt and molecules of at least one anhydrous ether solvent. In this or these embodiments, examples of lithium sulfonimide salt compositions that may be used for the anhydrous lithium sulfonimide salt include, but are not limited to, LiFSI, LiTFSI, and (LiFTFSI), and examples of anhydrous ether solvents that may be used for the one or more anhydrous ether solvents include, but are not limited to, dimethoxyethane, ethoxymethoxyethane, diethoxyethane, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, dioxane, and crown ethers, among others. Generally, any ether-based solvent can be used.In this or these embodiments, substantially all of the molecules of the at least one ether-based solvent are coordinated with . molecules of the at least one lithium sulfonimide salt. In one or more embodiments, the at least one ether-based solvent is present in the free solvent-free lithium sulfonimide salt composition in an amount of less than 5% by weight of the free solvent-free lithium sulfonimide salt composition.

[0068] In one or more embodiments, the electrolyte contains a cyclic carbonate, such as ethylene carbonate or propylene carbonate, and their derivatives, as an organic solvent. In one or more embodiments, the electrolyte contains a linear carbonate, such as dimethyl carbonate, diethyl carbonate, or ethyl methyl carbonate. In one or more embodiments, the electrolyte contains a cyclic ether, such as tetrahydrofuran or tetrahydropyran, and their derivatives, as an organic solvent. In one or more embodiments, the electrolyte contains a glyme, such as dimethoxyethane, diethoxyethane, triglyme, or tetraglyme, and their derivatives, as an organic solvent. In one or more embodiments, the electrolyte contains an ether, such as diethyl ether, or methylbutyl ether, and their derivatives, as an organic solvent.In one or more embodiments, the electrolyte contains a sulfonyl solvent such as N,N-dialkyl sulfamoyl fluoride and derivatives thereof and combinations thereof, as the organic solvent. In one or more embodiments, the electrolyte contains a mixture of organic solvents of the same type or a mixture of organic solvents of two or more types.

[0069] In one or more embodiments, the electrolyte may comprise one or more inorganic electrolytes selected from the group consisting of lithium silicates, lithium borates, lithium aluminates, lithium phosphates, lithium oxynitrides, lithium oxyborides, lithium silicosulfides, lithium borosulfides, lithium aluminosulfides, lithium phosphosulfides, and any combination thereof. In one or more embodiments, the electrolyte may comprise one or more solid ceramic electrolytes such as Ai-doped LLZO garnet oxide (Lig^Al o,25La3Zr2Oi2), perovskite (Lio^Lao^TiOs), LISICON (Lii4ZnGe40i6), NASICION (Lii>3Alo,3Tii>7(P04)3), thio-LISICON (LiioGeP2Si2), or other glass-based (LiPON) or glass-ceramic (70Li2S-30P2S5) materials or mixtures thereof.In one or more embodiments, the electrolyte may comprise a solid or gel-based polymer electrolyte containing POE (polyethylene oxide), POP (polypropylene oxide), PAN (polyacrylonitrile), PMMA (polymethyl methacrylate), PVC (polyvinyl chloride), PVDF (polyvinylidene fluoride), PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene), or mixtures thereof.

[0070] Although the foregoing examples of electrolytes are largely based on lithium-based salts, those skilled in the art will understand that the lithium-based salts can be replaced by suitable lithium-free salts.

[0071] Generally, an electrolyte of the present disclosure may have a salt concentration in a range of about 0.1 M to about 10 M, while in some embodiments, the salt concentration may be desired to be in a range of about 1 M to about 5 M, and in other embodiments, the salt concentration may be desired to be in a range of about 2 M to about 3 M.

[0072] The exemplary secondary battery 700 also includes a positive terminal 724 electrically connected to each of the cathodes 720 via corresponding electrodes 728(1) to 728(5). Similarly, the lithium metal battery further includes a negative terminal 732 electrically connected to the tabs 708A of the anodes 708 via the corresponding electrodes 736(1) to 736(4).

[0073] Various modifications and additions may be made without departing from the spirit and scope of the present disclosure. Features of each of the various embodiments described above may be combined with features of other described embodiments as appropriate to provide a multiplicity of combinations of features in new and related embodiments. Furthermore, although the foregoing describes a number of separate embodiments, what has been described herein is merely illustrative of the application of the principles of the present invention. Furthermore, although particular methods may herein be illustrated and / or described as being performed in a specific order, the order is highly variable within the ordinary skill in carrying out aspects of the present disclosure.Accordingly, the present description is intended to be taken solely by way of example, and not to otherwise limit the scope of the present invention.

[0074] In some aspects, the present disclosure relates to an anode for an electrochemical device. The anode includes a current collector having a thickness and an active region, the active region having first and second sides on opposite sides of the thickness; a first metal foil attached to the current collector on the first side of the active region; and a first electrically conductive layer between the current collector and the first metal foil, the first electrically conductive layer attaching the first metal foil to the current collector.

[0075] In one or more embodiments of the anode, the first electrically conductive layer comprises a layer of electrically conductive carbon.

[0076] In one or more embodiments of the anode, the electrically conductive carbon layer consists essentially of electrically conductive carbon particles and a binder.

[0077] In one or more embodiments of the anode, the electrically conductive carbon particles are present in an amount of about 70 wt% to about 90 wt% of the electrically conductive carbon layer.

[0078] In one or more embodiments of the anode, the electrically conductive layer has a thickness in a range of about 0.1 μm to about 5 μm.

[0079] In one or more embodiments of the anode, the electrically conductive layer has a thickness in a range of about 0.5 μm to about 2 μm.

[0080] In one or more embodiments of the anode, the electrically conductive layer has a thickness of about 1 μm.

[0081] In one or more embodiments of the anode, the electrically conductive layer is present at a surface loading of about 0.1 g / m2 to about 2 g / m2.

[0082] In one or more embodiments of the anode, the current collector comprises copper and the first metal foil comprises lithium.

[0083] In one or more embodiments of the anode, the current collector has a thickness in a range of about 4 μm to about 10 μm, and the first metal foil has a thickness in a range of about 15 μm to about 25 μm.

[0084] In one or more embodiments of the anode, the electrically conductive layer consists essentially of electrically conductive carbon particles and a binder.

[0085] In one or more embodiments of the anode, the electrically conductive carbon particles are present in an amount of about 70 wt% to about 90 wt% of the electrically conductive carbon layer.

[0086] In one or more embodiments of the anode, the electrically conductive layer has a thickness in a range of about 0.1 μm to about 5 μm.

[0087] In one or more embodiments of the anode, the electrically conductive layer has a thickness in a range of about 0.5 μm to about 2 μm.

[0088] In one or more embodiments of the anode, the electrically conductive layer has a thickness of about 1 μm.

[0089] In one or more embodiments of the anode, the electrically conductive layer is present at a surface loading of about 0.1 g / m2 to about 2 g / m2.

[0090] In one or more embodiments of the anode, the anode comprises a second metal foil attached to the current collector on the second side of the active region; and a second electrically conductive layer between the current collector and the second metal foil, the second electrically conductive layer attaching the second metal foil to the current collector.

[0091] In some aspects, the present disclosure relates to an electrochemical device comprising a cathode, an electrolyte and an anode of any of the anodes recited herein.

[0092] Exemplary embodiments have been disclosed above and illustrated in the accompanying drawings. Those skilled in the art will understand that various changes, omissions, and additions may be made to what is specifically disclosed herein without departing from the spirit and scope of the present disclosure.

Claims

Claims

1. A method of forming anodes for one or more electrochemical devices, wherein each of the anodes has an electrical tab, the method comprising: providing a current collector strip; laminating, on a first side of the current collector strip, a metal foil to the current collector strip in the form of multiple pieces of anode active material spaced apart from each other so as to provide a strip anode precursor that includes the pieces of anode active material and inter-piece regions not containing the metal foil;forming the anodes from the strip anode precursor such that each anode is formed from a corresponding piece of anode active material and the corresponding electrical tab is formed from one of the inter-piece regions, wherein forming the anodes comprises separating the anodes from the strip anode precursor; and prior to attaching the metal foil to the current collector strip, applying an electrically conductive coating at each location where the metal foil will be attached to the current collector strip and not applying the electrically conductive coating at each inter-piece region so as to form a piece of electrically conductive coating corresponding to a respective one of the pieces of anode active material.;

2. The method of claim 1, wherein the electrically conductive coating comprises electrically conductive particles and a binder.

3. The method of claim 2, wherein the electrically conductive particles comprise electrically conductive carbon particles.

4. The method of claim 3, wherein the binder is selected from the group consisting of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, carboxymethylcellulose, styrene-butadiene rubber, and any mixture thereof.

5. The method of claim 1, wherein the electrically conductive coating consists essentially of a binder and conductive carbon particles in an amount of about 70 wt% to about 90 wt% of the electrically conductive coating.

6. The method of claim 1, wherein applying the electrically conductive coating comprises applying the electrically conductive coating so as to have a cured thickness of about 0.1 µm to about 5 µm.

7. The method of claim 1, wherein applying the electrically conductive coating comprises applying the electrically conductive coating so as to have a cured thickness of about 0.5 µm to about 2 µm.

8. The method of claim 1, wherein applying the electrically conductive coating comprises applying the electrically conductive coating so as to have a cured thickness of about 1 µm.

9. The method of claim 1, further comprising using the conductive coating pieces to align individual sheets (416) of the metal foil (332) with the conductive coating pieces (328), the metal foil being supplied as individual sheets, prior to attaching the metal foil to the current collector strip.

10. The method of claim 9, wherein using the conductive coating pieces to align the sheets of alkali metal foil with the conductive coating pieces comprises using an optical detector to detect an edge of each of the conductive coating pieces.

11. The method of claim 1, wherein each piece of conductive coating has a size and shape and the corresponding piece of anode active material is aligned therewith and has a size and shape substantially identical to the size and shape of the piece of conductive coating.

12. The method of claim 1, wherein the current collector strip has a width and a length, and the pieces of anode active material are spaced apart from each other along the length of the current collector strip with the interpiece regions located therebetween.

13. The method of claim 12, wherein each of the pieces of anode active material has a width in the same direction as the width of the current collector strip, and the width of each of the pieces of anode active material is at least about 95% of the width of the current collector strip.

14. The method of claim 1, wherein each electrical tab has a tab length, and the method further comprising spacing the pieces of anode active material from each other by a minimum distance greater than or equal to the tab length.

15. The method of claim 1, wherein the method is carried out in a roll-to-roll process and the current collector strip is provided in a continuous ribbon.

16. The method of claim 1, further comprising attaching, on a second side of the current collector strip opposite the first side, a second metal foil to the current collector strip in the form of multiple pieces of anode active material on the reverse side spaced apart from each other and in alignment with respective corresponding pieces of the pieces of anode active material on the first side of the current collector strip.

17. The method of claim 1, wherein each anode has an active area, and the method further comprising sizing a corresponding one of the pieces of anode active material to substantially correspond to the active area of the anode.

18. The method of claim 1, wherein the anodes are formed at a 1:1 ratio to the pieces of anode active material.

19. The method of claim 1, wherein the anodes are formed at a 2:1 ratio to the pieces of anode active material.

20. The method of claim 1, wherein each interpiece region is used to form a single electrical tab of a corresponding one of the anodes.

21. A method according to claim 1, wherein each inter-piece region is used to form two electrical tabs corresponding, respectively, to those of the pieces of anode active material defining that inter-piece region.

22.

23.

24.

25.

26.

27.

28.

29. The method of claim 1, wherein the metal foil comprises lithium, and some of the anodes each have a width of at least 20 mm and a length of at least 120 mm. The method of claim 22, wherein the current collector strip comprises copper. The method of claim 22, wherein the metal foil comprises lithium, and some of the anodes each have a width of at least 50 mm and a length of at least 150 mm. The method of claim 1, wherein the current collector strip comprises a solid metal foil. The method of claim 1, wherein the current collector strip comprises a perforated metal foil. The method of claim 1, wherein the current collector strip comprises a metal mesh. The method of claim 1, wherein the current collector strip has a thickness in a range of about 4 µm to about 10 µm. The method of claim 28, wherein each piece of anode active material has a thickness in a range of about 15 µm to about 25 µm.

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