Electrodes for energy storage devices

Abstract

Disclosed herein is an electrode comprising an active layer, the active layer comprising a network of high aspect ratio carbon elements defining void spaces within the network, a plurality of electrode active material particles disposed in the void spaces within the network, and a polymeric binder, the polymeric binder comprising a first polymer, a polyamide, or an acrylate polymer, and a second polymer, the first polymer being a polymer comprising acid functional groups or salts of such acid functional groups.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Patent Application No. 63 / 417,206, filed October 18, 2022, which is incorporated herein by reference in its entirety. [Background technology]

[0002] Lithium batteries are used in many products, including medical devices, electric vehicles, airplanes, and consumer products such as laptop computers, cell phones, and cameras. Due to their high energy density, high operating voltage, and low self-discharge, lithium-ion batteries have overtaken the secondary battery market and continue to find new applications in products and evolving industries.

[0003] Generally, lithium ion batteries ("LIBs" or "LiBs") include an anode, a cathode, and an electrolyte material, such as an organic solvent containing a lithium salt. More specifically, the anode and cathode (collectively "electrodes") are formed by mixing either the anode or cathode active material with a binder and a solvent to form a paste or slurry, which is then coated onto a current collector, such as aluminum or copper, and dried to form a film on the current collector. The anode and cathode are then layered or coiled before being housed within a pressurized casing containing the electrolyte material, all of which together form the lithium ion battery.

[0004] Conventional electrodes use binders with sufficient adhesive and chemical properties to ensure that the film coated on the current collector maintains contact with the current collector, even when manipulated to fit into a pressurized battery casing. Because the film contains the electrode active material, if the film does not maintain sufficient contact with the current collector, it is likely to significantly interfere with the electrochemical performance of the battery. Furthermore, it has been important to select a binder that is mechanically compatible with the electrode active material so that it can withstand the degree of expansion and contraction of the electrode active material during battery charging and discharging.

[0005] Therefore, binders such as cellulosic binders or cross-linked polymer binders have been used to provide good mechanical properties, however, in conventional electrodes, the binders selected generally require environmentally unfriendly or toxic solvents for processing. Summary of the Invention

[0006] Disclosed herein is an electrode comprising an active layer, the active layer comprising a network of high aspect ratio carbon elements defining void spaces within the network, a plurality of electrode active material particles disposed in the void spaces within the network, and a binder component, the binder component comprising a first polymer containing an acid functional group or a salt of an acid functional group, a polyamide, or an acrylate polymer, such as in a polyacrylic latex, and a second polymer, preferably selected from a cellulose polymer and polyvinylpyrrolidone. The first polymer and the second polymer are present in the binder component as a polymer blend. The first polymer and the second polymer are not covalently or ionically bonded to each other.

[0007] Disclosed herein is an energy storage device comprising: a housing, an electrolyte, a first current collector; and an anode active material disposed on the first current collector, wherein the anode active material comprises a network of high aspect ratio carbon elements defining void spaces within the network; the energy storage device further comprises a plurality of anode active material particles disposed within the void spaces within the network; and an anode polymer binder, wherein the anode polymer binder comprises a first anode polymer comprising at least one of a polymer having acid functional groups or a polymer having a salt of such acid functional groups or a water soluble acrylate polymer such as in a polyacrylic latex; and optionally a second anode polymer, preferably a cellulosic polymer; the energy storage device further comprises a second current collector; and an anode active material disposed on the second current collector. and a cathode active material comprising a network of high aspect ratio carbon elements defining void spaces within the network; the energy storage device further comprising a plurality of cathode active material particles disposed within the void spaces within the network, wherein the cathode active material comprises a combination of nickel, manganese, and cobalt; and the energy storage device further comprising a cathode polymer binder, the cathode polymer binder comprising a first cathode polymer comprising at least one of a polymer comprising acid functional groups or a polymer comprising a salt of such acid functional groups, a polyamide, or an acrylate polymer, for example in a polyacrylic latex, and optionally a second cathode polymer preferably comprising polyvinylpyrrolidone, with the proviso that at least one of the anode polymer binder and the cathode polymer binder comprises the second polymer. [Brief explanation of the drawings]

[0008] The following is a brief description of the drawings, in which like elements are numbered alike and presented for the purpose of illustrating, but not for the purpose of limiting, exemplary embodiments disclosed herein. [Figure 1] 1A-1C are diagrams of electrodes according to various embodiments. [Figure 2]1 is a flowchart of a method for fabricating an electrode according to various embodiments. [Figure 3] FIG. 1 is a diagram of electrode placement in a pouch cell device. [Figure 4] 1 is a schematic cross-sectional depiction showing an embodiment of an energy storage device (ESD). DETAILED DESCRIPTION OF THE INVENTION

[0009] A more complete understanding of the components, processes, and apparatus disclosed herein can be obtained by reference to the accompanying drawings. These figures are merely schematic representations based on convenience and ease of illustrating the disclosure and, as such, are not intended to indicate the relative sizes and dimensions of the devices or their components and / or to define or limit the scope of the exemplary embodiments. Although specific terms are used in the following description for clarity, these terms are intended to refer only to the particular structures of the embodiments selected for illustration in the drawings and are not intended to define or limit the scope of the disclosure. It should be understood that in the drawings and the following description, like numerical designations refer to components of similar function.

[0010] Disclosed herein is an electrolysis cell comprising a housing containing electrodes (anode and cathode). The housing contains an electrolyte in contact with the anode and cathode. Both electrodes (anode and cathode) contain current collectors on which active layers are disposed. The active layers may be disposed on an optional adhesive layer in contact with the electrodes.

[0011] FIG. 1 is a diagram of an electrode (anode or cathode) according to various embodiments. In the illustrated example, an electrode 100 is provided. According to various embodiments, the electrode 100 includes a current collector 102 and an active layer 106. The electrode 100 may optionally include an adhesion layer 104. By way of example, the adhesion layer 104 includes a material that promotes adhesion between the current collector 102 and the active layer 106.

[0012] anode In an embodiment, with reference to FIG. 1 , the electrode (anode or cathode) includes a current collector 102, which is a conductive layer. For example, the current collector 102 may be a metal, a metal alloy, or the like. As another example, the current collector 102 is a metal foil. In some embodiments, the current collector 102 is an aluminum foil or an aluminum alloy foil. In some embodiments, the current collector 102 is a copper foil or a copper alloy foil. The current collector 102 has a thickness of less than 15 μm. The current collector 102 has a thickness of less than 10 μm. The current collector 102 has a thickness of less than 8 μm. The current collector 102 has a thickness of less than 5 μm. In an embodiment, the current collector 102 has a thickness of 3 to 15 μm. In some preferred embodiments, the current collector 102 has a thickness of about 6 μm to about 8 μm. In some embodiments, the current collector 102 is an aluminum foil or an aluminum alloy foil, and the current collector 102 has a thickness of about 6 μm.

[0013] The active layer 106 used in the anode can include a first anode conductive material, an optional second anode conductive material (the first anode conductive material and the second anode conductive material are sometimes collectively referred to as high aspect ratio carbon elements), an anode binder material, and an anode active material. The anode binder material includes a first polymer and preferably a second polymer. It is noted that, as contemplated herein, at least one of the anode and cathode includes two polymers in their binder material.

[0014] The anode active material can include a first anode active material and, optionally, a second anode active material (the first and second anode active materials are collectively referred to as electrode active material particles). The active layer for the anode (anode active layer) is produced by mixing a first anode conductive material, an optional second anode conductive material, a first anode binder material, an optional second anode binder material, the first anode active material, and the optional second anode active material with a solvent to form a mixture. The mixing promotes dispersion of the first anode conductive material, the second anode conductive material, the first anode active material, and the second anode active material in the mixture. The mixture is dried to remove the solvent, leaving a solid active material. The mixture may be dispersed onto a current collector or, optionally, onto an adhesive layer to form the anode active layer. The weight percentages of the various components forming the active layer are expressed as a function of the mixture (with solvent therein) and as a function of the solid anode active layer (without solvent therein).

[0015] At least one of the first anode conductive material and the second anode conductive material is a high-aspect ratio carbon element comprising a substantially cylindrical network of carbon atoms. The first anode conductive material can comprise a first set of carbon nanotubes or a plurality of bundles of first carbon nanotubes, and the second anode conductive material comprises a second set of carbon nanotubes or a plurality of bundles of second carbon nanotubes. The first anode conductive material and the second anode conductive material (individually and in combination) may be referred to herein as high-aspect ratio carbon elements. In one embodiment, the term "high-aspect ratio carbon element" refers to a carbonaceous element having one or more dimensions ("major dimension") that are significantly larger than the size of the element's lateral dimension ("minor dimension").

[0016] The first and second anode conductive materials can form a conductive permeating network that can transmit current between any two separated points located on the surface of the solid active layer (without solvent therein). In other words, physical contact or electron hopping between the first and second anode conductive materials within the anode active layer can transmit current from one surface of the active layer to the opposite surface. The permeating network includes voids between the high-aspect ratio carbon elements that house the anode active materials (first and second anode active materials).

[0017] In some embodiments, the anode active layer comprises (i) a network of high-aspect ratio carbon elements defining void spaces within the network; (ii) a plurality of electrode active material particles disposed within the void spaces within the network; and (iii) a polymer binder, an anode polymer binder, comprising a first polymer comprising at least one polymer having acid functional groups or a salt of such acid functional groups, or a water-soluble acrylate polymer, such as in a polyacrylic latex; and a second polymer, preferably a cellulose polymer. The first and second polymers are blended together to form the polymer binder. The first and second polymers are not covalently or ionically bonded to each other. A copolymer (third polymer) that facilitates blending of the first and second polymers may be used to compatibilize the first polymer with the second polymer. The third polymer (copolymer) may comprise the first and second polymers bonded to each other. Thus, the third polymer functions as a surfactant to compatibilize the first polymer with the second polymer.

[0018] The first anode conductive material can comprise high aspect ratio carbon elements bounded by a single carbon wall (SWCNT). In one embodiment, the first anode conductive material comprises single-walled carbon nanotubes. The single-walled carbon nanotubes have an outer diameter of 0.5 to 5.0 nanometers, preferably 1.0 to 3.5 nanometers. In embodiments, the single-walled carbon nanotubes have an aspect ratio (length to diameter ratio) greater than about 2.0, preferably greater than 5.0, preferably greater than 10.0, greater than 50, and more preferably greater than 100. In exemplary embodiments, the single-walled carbon nanotubes have an average aspect ratio of 5 to 200.

[0019] In one embodiment, the single-walled carbon nanotubes can have a length of greater than 6 nanometers, preferably greater than 10 nanometers, preferably greater than 15 nanometers, preferably greater than 30 nanometers, preferably greater than 50 nanometers, more preferably greater than 100 nanometers, preferably greater than 1 micrometer, preferably greater than 5 micrometers, preferably greater than 10 micrometers, more preferably greater than 15 micrometers, to at least 200 micrometers. In an exemplary embodiment, the single-walled carbon nanotubes have an average length of between 10 nanometers and 20 micrometers, preferably between 20 nanometers and 15 micrometers.

[0020] The single-walled carbon nanotubes are present in the mixture (the mixture including the first anode conductive material, the second anode conductive material, the first anode binder material, the second anode binder material, the first and second anode active materials, and the solvent) in an amount of 0.1 to 0.3 weight percent, preferably 0.15 to 0.25 weight percent, based on the total weight of the mixture.

[0021] The single-walled carbon nanotubes are present in the solid anode active material (the solid active material includes a first anode conductive material, a second anode conductive material, a first anode binder material, and a second anode binder material, and does not include a solvent) in an amount of 0.2 to 0.6 wt %, preferably 0.3 to 0.5 wt %, based on the total weight of the solid anode active material.

[0022] The second anode conductive material can comprise high aspect ratio carbon elements bounded by multiple carbon layers. In one embodiment, the second anode conductive material comprises multi-walled carbon nanotubes (MWNTs). The number of carbon layers in the multi-walled carbon nanotubes can be 2 or more, 5 or more, 10 or more, or 50 or more. According to various embodiments, the multi-walled carbon nanotubes comprise an average of 3 to 15 walls. In some embodiments, the multi-walled carbon nanotubes comprise an average of 4 to 12 walls. In some embodiments, the multi-walled carbon nanotubes comprise an average of 5 to 10 walls. In some embodiments, the multi-walled carbon nanotubes comprise an average of 6 to 7 walls. In some embodiments, the multi-walled carbon nanotubes comprise an average of at least 6 walls.

[0023] According to various embodiments, the active layer 106 includes multi-walled carbon nanotubes and single-walled carbon nanotubes. The multi-walled carbon nanotubes swell more than single-walled carbon nanotubes when wetted by an electrolyte in an energy storage device in which the electrode 100 is located. In some embodiments, the multi-walled carbon nanotubes swell at least 15% more than single-walled carbon nanotubes when wetted by an electrolyte in an energy storage device in which the electrode 100 is located. For example, the length of the multi-walled carbon nanotubes expands at least 15% more than the length of single-walled carbon nanotubes when wetted by an electrolyte in an energy storage device in which the electrode 100 is located. In some embodiments, the multi-walled carbon nanotubes swell at least 25% more than single-walled carbon nanotubes when wetted by an electrolyte in an energy storage device in which the electrode 100 is located. For example, the length of the multi-walled carbon nanotubes expands at least 25% more than the length of single-walled carbon nanotubes when wetted by an electrolyte in an energy storage device in which the electrode 100 is located. In some embodiments, the multi-walled carbon nanotubes swell at least 50% more than single-walled carbon nanotubes when wetted by an electrolyte in an energy storage device in which the electrode 100 is located. For example, the length of a multi-walled carbon nanotube expands by at least 50% more than the length of a single-walled carbon nanotube when wetted by an electrolyte. In some embodiments, the multi-walled carbon nanotube swells by up to 50% when wetted (e.g., the length of the multi-walled carbon nanotube increases by 50% after wetted by an electrolyte and / or the diameter of the multi-walled carbon nanotube increases by 50% after wetted, etc.).

[0024] According to various embodiments, the three-dimensional network of high-aspect ratio carbon elements 108 includes carbon nanotubes, where the carbon nanotubes are only multi-walled carbon nanotubes and / or carbon nanotube fragments. For example, the three-dimensional network of high-aspect ratio carbon elements 108 does not include single-walled carbon nanotubes or single-walled carbon nanotube fragments. According to various embodiments, the three-dimensional network of high-aspect ratio carbon elements 108 includes at least 99% carbon by weight. In some embodiments, the three-dimensional network of high-aspect ratio carbon elements 108 includes an electrically interconnected network of carbon elements that exhibits connectivity above a percolation threshold, where the network defines one or more highly conductive pathways having a length greater than 100 μm. The percolation threshold is the threshold at which conductive elements contact each other to provide a conductive network measured across any two points on any surface of the network.

[0025] The multi-walled carbon nanotubes have an outer diameter of 2.0 to 50 nanometers, preferably 5.0 to 40 nanometers, more preferably 6 to 10 nanometers. In one embodiment, the multi-walled carbon nanotubes have an aspect ratio (length to diameter ratio) greater than 5.0, preferably greater than 10.0, greater than 50, more preferably greater than 100, more preferably greater than 500.

[0026] In embodiments, the multi-walled carbon nanotubes have a length greater than 10 nanometers, preferably greater than 15 nanometers, preferably greater than 30 nanometers, preferably greater than 50 nanometers, preferably greater than 100 nanometers, preferably greater than 500 nanometers, preferably greater than 1 micrometer, preferably greater than 5 micrometers, preferably greater than 10 micrometers, more preferably greater than 15 micrometers. In exemplary embodiments, the multi-walled carbon nanotubes have an average length of between 10 nanometers and 20 micrometers, preferably between 20 nanometers and 15 micrometers.

[0027] According to various embodiments, the electrode includes multi-walled carbon nanotubes that are relatively long compared to those included in related art electrodes. The use of relatively long multi-walled carbon nanotubes in the electrode has been found to have beneficial mechanical and / or electrical properties. For example, multi-walled carbon nanotubes provide relatively good power output at low density. As another example, shorter multi-walled carbon nanotubes generally do not swell (e.g., expand) as much as longer multi-walled carbon nanotubes. Therefore, the use of shorter multi-walled carbon nanotubes loses (or reduces) some of the beneficial properties associated with carbon nanotube swelling. As an extreme example, carbon black does not exhibit swelling because it is merely a particle of carbon without entanglements such as those exhibited by a set of multi-walled carbon nanotubes. An indication that a certain amount of multi-walled carbon nanotubes has a length above a threshold length and therefore has sufficient swelling properties is observed during the calendering process, where a relatively large amount of pressure or effort to calender the slurry in connection with application to the foil indicates that the collective swelling (e.g., average swelling) of the multi-walled carbon nanotubes in the active layer meets a certain performance threshold. However, multi-walled carbon nanotubes are generally difficult to process. Treatment of multi-walled carbon nanotubes in connection with the preparation / formation of the active layer and / or electrode is gentler than processes for related art electrodes. Accordingly, processes according to various embodiments preserve longer multi-walled carbon nanotubes (e.g., shorter multi-walled carbon nanotubes are crushed, fragmented, broken, etc.). In some embodiments, the active layer of the electrode includes a set of multi-walled carbon nanotubes having an average length longer than the average length of the multi-walled carbon nanotubes in related art electrodes. According to various embodiments, the length distribution of the set of multi-walled carbon nanotubes is skewed toward the nominal length of the multi-walled carbon nanotubes. In one example, the nominal length of the multi-walled carbon nanotubes is about 16 microns. For example, the multi-walled carbon nanotubes are treated and / or adapted to reduce or minimize crushing or breaking of the multi-walled carbon nanotubes.The lengths of multi-walled carbon nanotubes in a network of high-aspect ratio carbon elements generally are the nominal lengths of the multi-walled carbon nanotubes, or the lengths of such multi-walled carbon nanotubes tend to be more distorted than the nominal lengths. In some embodiments, at least 75% of the multi-walled carbon nanotubes in a network of high-aspect ratio carbon elements are within 10% of the nominal length (e.g., 13.4 microns to about 15 microns). In some embodiments, at least 75% of the multi-walled carbon nanotubes in a network of high-aspect ratio carbon elements have a length of at least 12 microns. In some embodiments, at least 75% of the multi-walled carbon nanotubes in a network of high-aspect ratio carbon elements have a length of at least 13 microns. In some embodiments, at least 50% of the multi-walled carbon nanotubes in a network of high-aspect ratio carbon elements are within 10% of the nominal length (e.g., 13.4 microns to about 15 microns). In some embodiments, at least 50% of the multi-walled carbon nanotubes in a network of high-aspect ratio carbon elements have a length of at least 12 microns. In some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements have a length of at least 8 microns, hi some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements have a length of at least 13 microns.

[0028] According to various embodiments, the length distribution of the set of multi-walled carbon nanotubes is skewed toward the nominal length of the multi-walled carbon nanotubes. For example, the multi-walled carbon nanotubes are treated and / or adapted to reduce or minimize crushing or breakage of the multi-walled carbon nanotubes. The lengths of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements are generally at the nominal length of the multi-walled carbon nanotubes, or the lengths of such multi-walled carbon nanotubes tend to be more skewed toward the nominal length.

[0029] In some embodiments, at least 75% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements are within 10% of their nominal length (e.g., between 13.4 micrometers and about 15 micrometers). In some embodiments, at least 75% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements have a length of at least 12 micrometers. In some embodiments, at least 75% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements have a length of at least 13 micrometers. In some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements are within 10% of their nominal length (e.g., between 13.4 micrometers and about 15 micrometers). In some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements have a length of at least 12 micrometers. In some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements have a length of at least 13 micrometers.

[0030] The multi-walled carbon nanotubes are present in the mixture (the mixture including the first anode conductive material, the second anode conductive material, the first anode binder material, the second anode binder material, and the solvent) in an amount of 0.3 to 1.0 weight percent, preferably 0.4 to 0.9 weight percent, based on the total weight of the mixture.

[0031] The multi-walled carbon nanotubes are present in the solid anode active material (the solid active material includes a first anode conductive material, a second anode conductive material, a first anode binder material, and a second anode binder material, and does not include a solvent) in an amount of 0.8 to 2.6 wt %, preferably 1.0 to 1.8 wt %, based on the total weight of the solid anode active material.

[0032] In one embodiment, the second anode conductive material is present in the mixture or solid anode active material layer in an amount at least twice the amount of the first conductive material, based on the weight of each conductive material, hi one embodiment, the ratio of the weight of multi-walled carbon nanotubes to the weight of single-walled carbon nanotubes in the mixture or solid active material layer is at least 2:1.

[0033] The first anodic bonding agent comprises a first polymer that is at least soluble in water, alcohol, or a combination thereof. Other solvents may be used in conjunction with water or alcohol, as described in more detail below.

[0034] A suitable first polymer may be obtained from the polymerization of a monomer having structural formula (1):

[0035] [ka] wherein R1 is hydrogen or an alkyl group having 1 to 10 carbon atoms. Preferred alkyl groups have 2 to 5 carbon atoms. Examples of first polymers obtained from the polymerization of monomers having structural formula (1) include polyacrylic acid, polymethacrylic acid, or a combination thereof. The first polymer has a molecular weight of 5,000 to 2,000,000 grams / mole, preferably 10,000 to 1,000,000 grams / mole, and can be a thermoplastic material or a crosslinked material.

[0036] The first polymer of the anode binder can be formed from a latex (i.e., a dispersion of polymer particles in a solvent). Preferably, the solvent in the latex is water, alcohol, or a combination thereof. The first polymer of the anode binder can be polyacrylic acid or a salt thereof. The first anode polymer can be a homopolymer or a copolymer.

[0037] The first anode binder can be modified by blending a first polymer (obtained from the polymerization of a monomer having structural formula (1)) with a second polymer. The blend of the first and second polymers is preferably soluble in water, alcohol, or a combination thereof. It is also contemplated that one or a portion of the first or second polymer can be combined with a conductive material in a solvent (e.g., water, alcohol, or a combination thereof) to form an initial slurry. The initial slurry can then be combined with the active material and the remaining polymeric material. The second anode polymer can include an organic polymer selected from a wide variety of thermoplastic polymers. The second polymer can include an oligomer, homopolymer, copolymer, block copolymer, alternating block copolymer, random polymer, random copolymer, random block copolymer, graft copolymer, star block copolymer, dendrimer, polyelectrolyte (a polymer having some repeating groups containing an electrolyte), polyampholyte (a polyelectrolyte having both cationic and anionic repeating groups), ionomer, etc., or a combination comprising at least one of the foregoing organic polymers. The second polymer has a number average molecular weight greater than 10,000 grams / mole, preferably greater than 20,000 grams / mole, and more preferably greater than 50,000 grams / mole.

[0038] Examples of organic polymers, including the second polymer, include polyacetal, polyacrylic acid, polycarbonate, polyalkyd, polystyrene, polyolefin, polyester, polyamide, polyaramid, polyamideimide, polyarylate, polyurethane, epoxy, phenolic, silicone, polyarylsulfone, polyethersulfone, polyphenylene sulfide, polysulfone, polyimide, polyetherimide, polytetrafluoroethylene, polyetherketone, polyetheretherketone, polyetherketoneketone, polybenzoxazole, polyoxadiazole, polybenzothiazinophenothiazine, polybenzothiazole, polypyrazinoquinoxaline, polypyromellitimide, polyginoxaline, polybenzimidazole, polyoxyethylene ... Examples of the polyisoindoline include indole, polyoxoisoindoline, polydioxoisoindoline, polytriazine, polypyridazine, polypiperazine, polypyridine, polypiperidine, polytriazole, polypyrazole, polycarborane, polyoxabicyclononane, polydibenzofuran, polyphthalide, polyacetal, polyanhydride, polyvinyl ether, polyvinyl thioether, polyvinyl alcohol, polyvinyl ketone, polyvinyl halide, polyvinyl nitrile, polyvinyl ester, polysulfonate, polysulfide, polythioester, polysulfone, polysulfonamide, polyurea, polyphosphazene, polysilazane, polypropylene, polyethylene, polyethylene terephthalate, polyvinylidene fluoride, polysiloxane, or a combination thereof.

[0039] In a preferred embodiment, the second polymer is preferably soluble in water, alcohol, or a combination thereof. The second polymer may be polyacrylamide, polyamide, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, a cellulose-based polymer, an acrylic / maleic copolymer, a polyoligosaccharide, or a combination thereof. In a preferred embodiment, the second polymer of the anode polymer is a cellulose-based polymer.

[0040] The first polymer of the anode binder can be a derivative of the first polymer obtained by polymerizing a monomer of structural formula (1). In one embodiment, the derivative can include a salt of the first polymer. Examples of the salt of the first polymer include tetradecyldimethylbenzylammonium salt of polyacrylic acid, benzethonium salt of polyacrylic acid, or other salts of polyacrylic acid.

[0041] The first anode polymer can be present in an amount of 2 to 3 weight percent (wt%), preferably 2.1 to 2.9 wt%, based on the total weight of the mixture (wherein the mixture includes a first anode conductive material, a second anode conductive material, a first anode binder material, a second anode binder material, first and second anode active materials, and a solvent). The first anode polymer can be present in an amount of 5 to 9 wt%, preferably 6 to 8 wt%, based on the total weight of the solid active layer.

[0042] The second anodic polymer present in the active layer is preferably also a water-soluble polymer. The second anodic binder is chemically different from the first anodic polymer. In one embodiment, the second anodic polymer can be a water-soluble, naturally occurring polymer. Examples of naturally occurring polymers for use as the second anodic binder include cellulose and cellulose derivatives (e.g., hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose, cellulose acetate, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose acetate butyrate, and cellulose ethers such as ethyl cellulose, or combinations thereof), sugars (glucose, sucrose, lactose, galactose, fructose, mannitol, sorbitol, or combinations thereof), ionic complexes of cellulose, gums (e.g., acacia, alginate, carrageenan, guar, karaya, pectin, tragacanth, xanthan, or combinations thereof).

[0043] Other examples of second anode polymers include polyethylene oxide (PEO), polyethers, derivatives of poly(ethylene glycol) (PEG), fluorine-containing polymers, particularly poly(vinylidene difluoride) (PVDF), polyurethane (PU), polytetrafluoroethylene (PTFE), alginate (Alg), denatured DNA / Alg, Alg-catechol, polyacrylic acid (PAA)-catechol, carboxymethyl chitosan, guar gum, agarose, konjac glucomannan, carboxymethylated gellan gum, PDA-PAA-PEO, pectin / PAA, partially lithiated PAA and Nafion, sequence-defined peptoids, PMDOPA, branched PAA, NaPAA-g-CMC, CS-g-PAANa, PVA-g-PAA, GC-g-LiPAA, PVDF-g-PAA, branched PAA-PEG, CS-g-PANI, hyperbranched β-cyclodextrin, double-stranded natural xanthan gum, Li-Nafion, PAA / CMC, crosslinked PAA / PVA, glycerol-crosslinked PEDOT:PSS, maleic anhydride (MAH)-crosslinked corn starch, MAH-crosslinked CMC, crosslinked natural GG polymer, crosslinked chitosan, CS-CG+GA, crosslinked dextrin, crosslinked CMC-PEG, crosslinked hyperbranched PEI, crosslinked PAM hydrogel, crosslinked PU elastomer, crosslinked PVA-PEI, TMM-functionalized PVA network, polymers containing polyamides (e.g., nylon), functionalized polyamides, copolymers of PEO and polyamides, self-healing polymers, PAA-Upy supramolecules, self-healing PAU-g-PEG, Ca 2+ Crosslinked SA hydrogel, (Fe 3+ ) cross-linked (PANa 0.8 Fe y ), Sn 4+ Cross-linked PEDOT:PSS, PAA-PEG-PBI, cross-linked CMC-CPAM, metallopolymer, Si@Fe 3+-PDA-PAA, β-CDp / 6 AD, slide-ring PR-PAA, conductive PFFOMB, PEG-grafted PFP, PF-COONa, PFPQ-COONa, pyrene-based (PPyE), pyrene-based (PPyMAA), pyrene-based (PPyMADMA), PANI, FA-doped PEDOT:PSS, stretchable conductive adhesive, poly(phenanthrenequinone), cyclized PAN, PAA-P(HEA-co-DMA), PEDOT:PSS / PEO / PEI, PAA / PVA + elastic gel polymer electrolyte, PAA + BFPU, hybrids of PU and poly(acrylic acid) (PAA), and copolymers of any subset of the above.

[0044] In a preferred embodiment, the second anode polymer comprises or consists of carboxymethyl cellulose (CMC).

[0045] The second anode polymer can be present in an amount of 0.1 to 1.0 wt %, preferably 0.2 to 0.6 wt %, based on the total weight of the mixture. The second anode binder can be present in an amount of 0.2 to 2 wt %, preferably 0.4 to 1.6 wt %, based on the total weight of the solid active layer.

[0046] In one embodiment, if the first and second anode polymers are not miscible with each other, they can be blended together with a third polymer that comprises a copolymer having two components, one component (the first component) of the copolymer being miscible with the first anode polymer and the second component being miscible with the second anode polymer.

[0047] The anode active material can be disposed within the voids surrounded by the conductive network formed by the high-aspect ratio carbon elements. The anode active material can include a first anode active material. The first anode active material can include silicon monoxide (SiOx) because its capacity and cycle life are higher and longer than those of graphite and silicon, respectively. In one embodiment, the first anode active material includes carbon-coated silicon monoxide. In one embodiment, the carbon includes graphite or another carbonaceous material, such as carbon nanotubes, carbon black, or a combination thereof. The use of carbon-coated silicon monoxide results in a storage device with a high-capacity anode that exhibits an initial coulombic efficiency (ICE) of greater than 90%.

[0048] The first anode active material is present in the mixture (wherein the mixture is a first anode conductive material, a second anode conductive material, a first anode binder material, a second anode binder material, a first anode active material, a second anode active material, and a solvent) in an amount of 25 to 33 wt %, preferably 26 to 31 wt %, based on the total weight of the mixture.

[0049] The first anode active material is present in the anode active layer in an amount of 67 to 95% by weight, based on the total weight of the anode active layer.

[0050] The anode active material can include a second anode active material. The second anode active material can include graphite. The graphite can be natural graphite or artificial graphite. In a preferred embodiment, the graphite is artificial graphite. The graphite is added in granular form (powder state). In one embodiment, the graphite can be intercalated.

[0051] The graphite may be added in an amount of 0.75 to 6 wt %, preferably 1 to 5 wt %, based on the total weight of the mixture, and in an amount of 2.5 to 18 wt %, preferably 4 to 16 wt %, based on the total weight of the solid active layer.

[0052] In one embodiment, SiOx / graphite anode (SiOx content = about 20 wt%) based electrodes and their material synthesis and manufacturing method: mass loading 8-14 mg / cm 2 , and reversible specific capacity ≥ 550mAh / g. SiOx / graphite anode-based Li-ion-based electrolytes, especially for batteries, have long-life performance: -30 to 60°C. Ni-rich NMC cathode / SiOx + graphite / carbon +-based Li-ion battery pouch cells have high energy, high power density, and long cycle life: capacity ≥ 5Ah, specific energy ≥ 300Wh / kg, energy density ≥ 800Wh / L, and cycle life exceeding 500 cycles under 1C rate charge / discharge and ultra-high-power high-rate charge / discharge C rate (up to 5C rate).

[0053] The mixture for producing the anode active layer further includes a solvent. The solvent is preferably the same as that used to disperse the first anode polymer, the second anode polymer, the first anode conductive material, and the second conductive material to form the mixture. The mixture is then disposed on a current collector to form the active layer.

[0054] Suitable solvents are water, alcohol, or a combination thereof. Examples of alcohols include ethanol, methanol, propanol, butyl alcohol, ethylene glycol, propylene glycol, or a combination thereof. In addition to water and alcohol, other solvents may be added to facilitate solubilization and / or dispersion of the polymer. Examples of other solvents include polar solvents, nonpolar solvents, etc. The addition of other solvents should preferably not change the solubility of the polymer in water or alcohol. Liquid aprotic polar solvents, such as propylene carbonate, ethylene carbonate, butyrolactone, acetonitrile, benzonitrile, nitromethane, nitrobenzene, sulfolane, dimethylformamide, N-methylpyrrolidone, etc., or combinations thereof, can be added to water or alcohol to dissolve the polymer. Polar protic solvents, such as acetonitrile, nitromethane, acetone, dimethyl sulfoxide, dimethylformamide, etc., or combinations thereof, can also be used. Other nonpolar solvents, such as benzene, toluene, methylene chloride, carbon tetrachloride, hexane, diethyl ether, tetrahydrofuran, etc., or combinations thereof, can also be used. Co-solvents, including at least one aprotic polar solvent and at least one non-polar solvent, can also be utilized to modify the solubilizing power of the solvent.

[0055] When water and alcohol are used as the solvent for the active layer (used in the anode), the ratio of water to alcohol is 80:20 to 95:5, preferably 88:12 to 92:8. In an exemplary embodiment, the ratio of water to alcohol is 90:10.

[0056] The solvent is present in an amount of 60 to 95% by weight, preferably 65 to 90% by weight, based on the total weight of the mixture. The solid active layer is preferably free of solvents (water and alcohol).

[0057] The active layer 106 has an average thickness between 20 microns and 200 microns. In some embodiments, the active layer 106 has an average thickness between 20 microns and 30 microns. In some embodiments, the active layer 106 has an average thickness of about 100 microns.

[0058] According to various embodiments, the active layer 106 expands (e.g., swells) by less than 10% when wetted by the electrolyte. For example, the thickness of the active layer 106 (after being wetted by the electrolyte) is less than 110% of the thickness of the active layer 106 in the absence of the electrolyte.

[0059] The mixture including the binder, conductive material, and solvent may also contain additional additives, such as dispersants, surfactants, etc., or combinations thereof. The surfactants and dispersants are used to provide a surfactant layer on the high aspect ratio carbon elements.

[0060] The surface treatment can include a surfactant layer bonded to the high aspect ratio carbon elements 108 and including a plurality of surfactant elements each having a hydrophobic end and a hydrophilic end, the hydrophobic end disposed proximal to one surface of the high aspect ratio carbon elements 108 and the hydrophilic end disposed distal to that surface of the one of the high aspect ratio carbon elements 108. In some embodiments, the surface treatment includes at least a portion of a polymer additive. In some embodiments, the surface treatment includes a material soluble in a solvent having a boiling point less than 200°C. In some embodiments, the surface treatment includes a material soluble in a solvent having a boiling point less than 185°C.

[0061] According to various embodiments, the active layer 106 includes a polymer that can function as a dispersant. The dispersant can be selected based on its miscibility with water and / or alcohol, such as ethanol. In some embodiments, the dispersant is a water-soluble polymer. In some embodiments, the dispersant corresponds to or includes polyvinylpyrrolidone (PVP). The PVP used in the dispersant can be a PVP with a relatively high molecular weight.

[0062] According to various embodiments, the active layer 106 comprises about 25% dispersant by weight of the active layer 106. In some embodiments, the amount of dispersant in the active layer 106 is between 10% and 50% by weight of the active layer 106. In some embodiments, the amount of dispersant in the active layer 106 is between 15% and 40% by weight of the active layer 106. In some embodiments, the amount of dispersant in the active layer 106 is between 20% and 30% by weight of the active layer 106.

[0063] In various embodiments, the surfactant used to form the surface treatment includes one or more of hexadecyltrimethylammonium hexafluorophosphate (CTAP), hexadecyltrimethylammonium tetrafluoroborate (CTAB), hexadecyltrimethylammonium acetate, hexadecyltrimethylammonium nitrate, cocamidopropyl betaine, N-(cocoalkyl)-N,N,N-trimethylammonium methyl sulfate, cocamidopropyl betaine, and the like, or combinations thereof.

[0064] Cathode The cathode comprises one or more polymer binders (cathode polymer binders), one or more active materials, and a conductive material. The one or more polymer binders, the one or more active materials, and the conductive material are blended with a solvent to form a cathode mixture. The cathode mixture is then placed on a current collector (typically metal) and dried to form a solid cathode active layer.

[0065] As described above, the polymer binder for at least one of the anode and cathode comprises two polymers. Thus, the cathode polymer binder (used in the cathode) can comprise a first cathode polymer containing acid functional groups or salts of such acid functional groups, a polyamide, or an acrylate polymer, such as in a polyacrylic latex. The cathode polymer binder (used in the cathode) preferably also comprises a second cathode polymer. The second cathode polymer preferably comprises polyvinylpyrrolidone (PVP).

[0066] The polyamide (used in the first cathode polymer) can include aliphatic polyamides, aromatic polyamides, or combinations thereof. In one embodiment, the polyamide includes the general family of resins known as nylons, which are characterized by the presence of amide groups (—C(O)NH—). Any amide-containing polymer can be used individually or in combination, with nylon-6 and nylon-6,6 being suitable polyamide resins available from a variety of commercial sources. However, other polyamides, such as nylon-4, nylon-4,6 (PA 46), nylon-12, nylon-6,10, nylon-6,9, nylon-6,12, nylon-9T, copolymers of nylon-6,6 and nylon-6, nylon 610 (PA 610), nylon 11 (PA 11), nylon 12 (PA 12), nylon 6-3-T (PA 6-3-T), polyarylamide (PA MXD 6), polyphthalamide (PPA) and / or polyether block amides, and others, such as amorphous nylon, may also be useful. Blends of various polyamides, as well as various polyamide copolymers, may also be useful.

[0067] Polyamides can be obtained by many well-known methods, such as those described in U.S. Patents 2,071,250, 2,071,251, 2,130,523, 2,130,948, 2,241,322, 2,312,966, and 2,512,606. For example, nylon-6 is a polymerization product of caprolactam. Nylon-6,6 is a condensation product of adipic acid and 1,6-diaminohexane. Similarly, nylon 4,6 is a condensation product of adipic acid and 1,4-diaminobutane. In addition to adipic acid, other diacids useful for preparing nylons include azelaic acid, sebacic acid, dodecanedioic acid, and terephthalic and isophthalic acids. Other useful diamines include m-xylylenediamine, di-(4-aminophenyl)methane, di-(4-aminocyclohexyl)methane, 2,2-di-(4-aminophenyl)propane, 2,2-di-(4-aminocyclohexyl)propane, etc. Copolymers of caprolactam with diacids and diamines are also useful.

[0068] Polyamides are generally derived from the polymerization of organic lactams having from 4 to 12 carbon atoms. In one embodiment, the lactam is represented by formula (I):

[0069] [ka] wherein n is 3 to 11. In one embodiment, the lactam is epsilon-caprolactam, where n is equal to 5.

[0070] The polyamide may be synthesized from amino acids having 4 to 12 carbon atoms. In one embodiment, the amino acid is represented by formula (II):

[0071] [ka] wherein n is 3 to 11. In one embodiment, the amino acid is epsilon-aminocaproic acid, where n is equal to 5. The polyamide may be polymerized from an aliphatic dicarboxylic acid having 4 to 12 carbon atoms and an aliphatic diamine having 2 to 12 carbon atoms. In one embodiment, the aliphatic diamine is represented by formula (III): H2N-(CH2) n -NH2(III) wherein n is from about 2 to about 12. In one embodiment, the aliphatic diamine is hexamethylenediamine (H2N(CH2)6NH2). In one embodiment, the molar ratio of dicarboxylic acid to diamine is from 0.66 to 1.5. Within this range, it is generally beneficial for the molar ratio to be 0.81 or greater. In another embodiment, the molar ratio is 0.96 or greater. In yet another embodiment, the molar ratio is 1.22 or less. In yet another embodiment, the molar ratio is 1.04 or less. Examples of polyamides useful in the present invention include nylon 6, nylon 6,6, nylon 4,6, nylon 6,12, nylon 10, or a combination comprising at least one of the foregoing polyamides.

[0072] The acid-functional cathode polymer can include polyacrylic acid, polyacrylic acid copolymers, or combinations thereof, which are listed and described above and will not be repeated here for the sake of brevity.

[0073] Acrylate copolymers include polyacrylates or polymethacrylates copolymerized with another polymer that does not have the exact chemical structure of a polyacrylate or polymethacrylate. Acrylates can be obtained from the polymerization of monomers having the following structure, represented by formula (4) or formula (5):

[0074] [ka] where R1 is hydrogen or an alkyl group having 1 to 10 carbon atoms, and R2 is C 1~10 Alkyl, C 3~10 Cycloalkyl, or C 7~10In one embodiment, the polyacrylate contains fluorine atoms and is obtained by polymerization of a monomer having at least one fluorine atom substituent and a structure represented by formula (5):

[0075] [ka] where R1 is hydrogen or an alkyl group having 1 to 10 carbon atoms, and R3 is C 2~10 Suitable polymeric acrylates include polyacrylate, polymethyl acrylate, polymethyl methacrylate, polybutyl acrylate, or combinations thereof.

[0076] In one embodiment, polyacrylic acid (discussed in more detail above) is copolymerized with a polyamide (discussed in more detail above) or with one of the polyacrylates (discussed in more detail above) to form the first cathode polymer binder.

[0077] The first cathode polymer binder is present in an amount of 0.1 to 0.4 wt %, preferably 0.15 to 0.375 wt %, based on the weight of the cathode mixture (including the cathode polymer binders (first and second cathode polymer binders), the cathode active material, the cathode conductive material, and the solvent). The first cathode polymer binder is present in the cathode active layer in an amount of 0.2 to 0.5 wt %, preferably 0.25 to 0.45 wt %, based on the total weight of the cathode active layer.

[0078] The cathode active layer preferably includes a second cathode polymer binder comprising polyvinylpyrrolidone (PVP), which in addition to functioning as the second cathode polymer binder, can also function as a dispersing agent for the cathode active material and the cathode conductive filler.

[0079] The second cathode polymer binder is present in an amount of 0.1 to 0.4 wt %, preferably 0.15 to 0.375 wt %, based on the weight of the cathode mixture (including the cathode polymer binders (first and second cathode polymer binders), the cathode active material, the cathode conductive material, and the solvent). The second cathode polymer binder is present in the cathode active layer in an amount of 0.2 to 0.5 wt %, preferably 0.25 to 0.45 wt %, based on the total weight of the cathode active layer.

[0080] The cathode mixture includes a conductive material. This conductive material can include high-aspect ratio carbon elements. The high-aspect ratio carbon elements can include single-walled carbon nanotubes, multi-walled carbon nanotubes, or a combination thereof, as described above. For example, the cathode conductive material can include multi-walled nanotubes that form a percolated network with voids enclosed by the multi-walled carbon nanotubes. The voids contain the cathode active material. Multi-walled carbon nanotubes have been described in detail above and will not be described in detail again for the sake of brevity. The multi-walled carbon nanotubes are present in an amount of 0.1 to 0.5 wt %, preferably 0.2 to 0.4 wt %, based on the weight of the cathode mixture (including the cathode polymer binders (first and second cathode polymer binders), the cathode active material, the cathode conductive material, and the solvent). The multi-walled carbon nanotubes are present in the cathode active layer in an amount of 0.2 to 0.7 wt %, preferably 0.3 to 0.6 wt %, based on the total weight of the cathode active layer.

[0081] The cathode active material can include a nickel-rich combination of nickel, manganese, and cobalt. Lithium-nickel-manganese-cobalt-oxide (LiNiMnCoO), abbreviated as NMC, offers high overall performance, excellent specific energy, and the lowest self-heating rate of all mainstream cathode powders. NMC powder may contain 20-40 wt% nickel, 20-40 wt% manganese, and 20-40 wt% cobalt, based on the total weight of the NMC blend. While the term "NMC powder" can refer to various blends, it is desirable to use a blend containing 33 wt% nickel, 33 wt% manganese, and 33 wt% cobalt. This blend, sometimes referred to as 1-1-1, is useful for applications with frequent cycling (automotive, energy storage) due to the reduced material cost resulting from the lower cobalt content.

[0082] As described above, the cathode active material is contained within a network of high aspect ratio active material present in the cathode active layer. The cathode active material is present in an amount of 55 to 75 wt %, preferably 60 to 70 wt %, based on the total weight of the cathode mixture (the mixture used to fabricate the cathode active layer, containing the cathode polymer binders (first and second cathode polymer binders), the cathode active material, the cathode conductive material, and the solvent). The cathode active material is present in the cathode active layer (excluding the solvent) in an amount of 95 to 98.5 wt %, based on the total weight of the cathode active layer.

[0083] In one embodiment, the cathode polymer binder (first and second cathode polymers), cathode active material, cathode conductive material, and solvent are blended together to form a cathode mixture in the form of a slurry. This can be done in a single step, or it can involve first preparing an initial slurry of the cathode conductive material and at least a portion of one of the cathode polymers, which is then further mixed with the cathode active material and any remaining portions of the cathode polymer. The blending process promotes dispersion of the cathode conductive material and cathode active material to form a permeable network throughout the volume of the cathode active layer when the solvent is removed. In an embodiment, the cathode mixture (in slurry form) is placed on a current collector after mixing is complete. The current collector with the cathode mixture placed thereon is sheared and compressed in a roll mill. The use of a roll mill facilitates bonding between the cathode active layer and the current collector.

[0084] Figure 2 is a flowchart of a method of making an electrode according to various embodiments. A description of process 600 is provided with respect to electrode 100 of Figure 1. Referring to Figure 2, in some embodiments, active layer 106 of electrode 100 can be formed using process 600. As 610, high aspect ratio carbon elements and a surface treatment material (e.g., a surfactant or polymeric material described herein) are combined with a solvent (of the type described herein) to form an initial slurry.

[0085] At 620, the initial slurry is treated to ensure good dispersion of the solid materials in the slurry. In some embodiments, this treatment involves introducing mechanical energy into the mixture of solvent and solid materials (e.g., using an ultrasonicator, sometimes called a "sonifier") or other suitable mixing device (e.g., a high-shear mixer). In some embodiments, the mechanical energy introduced into the mixture is at least 0.4 kilowatt-hours per kilogram (kWh / kg), 0.5 kWh / kg, 0.6 kWh / kg, 0.7 kWh / kg, 0.8 kWh / kg, 0.9 kWh / kg, 1.0 kWh / kg, or more. For example, the mechanical energy introduced into the mixture per kilogram of mixture can be in the range of 0.4 kWh / kg to 1.0 kWh / kg, or any subrange thereof, such as 0.4 kWh / kg to 0.6 kWh / kg.

[0086] In some embodiments, an ultrasonic bath mixer may be used. In other embodiments, a probe sonicator may be used. Probe sonication can be significantly more powerful and effective when compared to an ultrasonic bath for nanoparticle applications. The high shear forces generated by ultrasonic cavitation have the ability to break down particle agglomerates, resulting in smaller, more uniform particle sizes. Among other things, sonication can result in a stable and homogeneous suspension of solids in a slurry. Generally, this results in dispersion and deagglomeration and other breakdown of solids. An example of a probe sonication device is the Q Series Probe Sonicator available from QSonica LLC (Newtown, Connecticut). Another example is the Branson Digital SFX-450 sonicator available from Thomas Scientific (Swedesboro, New Jersey).

[0087] However, in some embodiments, the localized nature of each probe within a probe assembly can result in non-uniform mixing and suspension. This can be the case, for example, with large samples. This can be addressed by using a setup with a continuous flow cell and appropriate mixing. For example, in such a setup, mixing of a slurry achieves a reasonably uniform dispersion.

[0088] In some embodiments, the initial slurry, once processed, has a viscosity in the range of 5,000 cps to 25,000 cps, or any subrange thereof, such as 6,000 cps to 19,000 cps.

[0089] At 630, a surface treatment may be fully or partially formed on the high-aspect ratio carbon elements in the initial slurry. In some embodiments, the surface treatment may self-assemble at this stage. The resulting surface treatment may include functional groups or other features that can promote adhesion between the high-aspect ratio carbon elements and the active material particles, as described in further steps below.

[0090] At 640, the active material particles may be combined with the initial slurry to form a final slurry that includes the active material particles with the high aspect ratio carbon elements having the surface treatment formed thereon.

[0091] In some embodiments, the active material may be added directly to the initial slurry. In other embodiments, the active material may first be dispersed in a solvent (e.g., using the techniques described above for the initial solvent) to form an active material slurry. This active material slurry may then be combined with the initial slurry to form the final slurry.

[0092] At 650, the final slurry is processed to ensure good dispersion of the solid materials in the final slurry. In various embodiments, any suitable mixing process known in the art may be used. In some embodiments, this processing may use techniques described above with reference to 620. In some embodiments, a planetary mixer, such as a multi-shaft (e.g., three or more) planetary mixer, may be used. In some such embodiments, the planetary mixer may feature multiple blades, for example, two or more mixing blades and one or more (e.g., two, three, or more) dispersion blades, such as a disk dispersion blade.

[0093] In some embodiments, the matrix entangled with the active material may fully or partially self-assemble during 650. In some embodiments, an interaction between the surface treatment and the active material facilitates the self-assembly process.

[0094] In some embodiments, the final slurry, once processed, has a viscosity in the range of 1,000 cps to 10,000 cps, or any subrange thereof, for example, 2,500 cps to 6000 cps.

[0095] At 660, the active layer 106 is formed from the final slurry. In some embodiments, the final slurry may be wet-cast directly onto the current collector conductive layer 102 (or optional adhesive layer 104) and dried. As an example, casting may form the active layer 106 by applying at least one of heat and vacuum until substantially all of the solvent and any other liquids are removed. In some such embodiments, it may be desirable to protect various portions of the underlying layers. For example, protecting the underside of the conductive layer 102 may be desirable if the electrode 100 is intended for double-sided operation. Protection may include, for example, protecting from the solvent by masking certain areas or providing a drain for removing the solvent.

[0096] In other embodiments, the final slurry can be at least partially dried elsewhere using any suitable technique (e.g., roll-to-roll layer application) and then transferred onto adhesive layer 104 or conductive layer 102 to form active layer 106. In some embodiments, the wet-mixed slurry may be placed onto an intermediate material having a suitable surface and dried to form a layer (e.g., active layer 106). While any material having a suitable surface can be used as the intermediate material, an exemplary intermediate material includes PTFE because its properties facilitate its subsequent removal from the surface. In some embodiments, the specified layer is formed in a press to provide a layer exhibiting a desired thickness, area, and density.

[0097] In some embodiments, the final slurry may be formed into a sheet and coated onto the adhesive layer 104 or the conductive layer 102, as appropriate. For example, in some embodiments, the final slurry may be applied through a slot die to control the thickness of the applied layer. In other embodiments, the slurry may be applied and then leveled to the desired thickness using, for example, a doctor blade. Various other techniques can be used to apply the slurry. For example, coating techniques may include, but are not limited to, comma coating, comma reverse coating, doctor blade coating, slot die coating, direct gravure coating, air doctor coating (air knife), chamber doctor coating, offset gravure coating, one-roll kiss coating, reverse kiss coating with a small diameter gravure roll, bar coating, three reverse roll coating (top feed), three reverse roll coating (fountain die), reverse roll coating, etc.

[0098] The viscosity of the final slurry can vary depending on the application technique. For example, for comma coating, the viscosity can range from about 1,000 cps to about 200,000 cps. Lip die coating provides a coating with a slurry exhibiting a viscosity of about 500 cps to about 300,000 cps. Reverse kiss coating provides a coating with a slurry exhibiting a viscosity of about 5 cps to 1,000 cps. In some applications, each layer can be formed in multiple passes.

[0099] In some embodiments, the active layer 106 formed from the final slurry may be compressed (e.g., using a calendering device) before or after being applied to the electrode 100. In some embodiments, the slurry may be partially or completely dried (e.g., by applying heat, vacuum, or a combination thereof) before or during the compression process. For example, in some embodiments, the active layer may be compressed to a final thickness (e.g., in a direction perpendicular to the current collector layer 102) that is less than 90%, 80%, 70%, 50%, 40%, 30%, 20%, or 10% or less of its pre-compression thickness.

[0100] In various embodiments, if a partially dried layer is formed during the coating or pressing process, the layer may then be completely dried (e.g., by applying heat, vacuum, or a combination thereof). In some embodiments, substantially all of the solvent is removed from the active layer 106.

[0101] In some embodiments, the solvent used to form the slurry is recovered and recycled into the slurry making process.

[0102] In some embodiments, the active layer 106 may be compressed, for example, to break down some of the constituent high aspect ratio carbon elements or other carbonaceous materials and increase the surface area of ​​each layer. In some embodiments, this compression process may increase one or more of adhesion between the layers, ion transport rates within the layers, and surface area of ​​the layers. In various embodiments, compression may be applied before or after each layer is applied or formed into the electrode 100.

[0103] In some embodiments where calendering is used to compress the active layer 106, the calendering apparatus may be set with a gap spacing equal to 90%, 80%, 70%, 50%, 40%, 30%, less than 20%, or 10% or less of the pre-compression thickness of the layer (e.g., set at about 33% of the pre-compression thickness of the layer). The calender rolls can be configured to provide a suitable pressure, for example, greater than 1 ton per cm of roll length, greater than 1.5 ton per cm of roll length, greater than 2.0 ton per cm of roll length, greater than 2.5 ton per cm of roll length, or more. In some embodiments, the compressed active layer has a density in the range of 1 g / cc to 10 g / cc, or any subrange thereof, e.g., 2.5 g / cc to 4.0 g / cc. In some embodiments, the calendering process can be carried out at a temperature in the range of 20°C to 140°C, or any subrange thereof. In some embodiments, the active layer 106 can be preheated prior to calendering, for example, to a temperature in the range of 20° C. to 100° C., or any subrange thereof.

[0104] Once the electrode 100 is assembled, it can be used to assemble an energy storage device. Assembly of the energy storage device may follow conventional steps used to assemble an electrode with a separator and place it into a housing, such as a canister or pouch, and may further include additional steps to add electrolyte and seal the housing.

[0105] In various embodiments, the process 600 may include any of the following features (individually or in any suitable combination):

[0106] In some embodiments, the initial slurry has a solids content in the range of 0.1% to 20.0% by weight (or any subrange thereof), hi some embodiments, the final slurry has a solids content in the range of 10.0% to 80% by weight (or any subrange thereof).

[0107] A 3D carbon scaffold or matrix holds the active material particles together, forming a cohesive layer that is also strongly attached to the metal current collector. Such an active material structure is created during slurry preparation, followed by a roll-to-roll ("R2R") coating and drying process. One of the main advantages of this technology is its scalability and "drop-in" nature, as various embodiments are compatible with conventional electrode manufacturing processes.

[0108] The 3D carbon matrix is ​​formed during slurry preparation using the techniques described herein, where the high-aspect ratio carbon material is appropriately dispersed and chemically functionalized, for example, using a two-step slurry preparation process (e.g., of the type described above with reference to process 600 in Figure 2). The chemical functionalization is designed to form an organized self-assembled structure with the surface of active material particles, such as NMC particles for use in a cathode, or silicon particles ("Si") or silicon oxide ("SiOx") particles for an anode. The slurry so formed may be based on water and / or alcohol solvents for the cathode and water for the anode, where such solvents evaporate very easily during the manufacturing process and are handled during the manufacturing process. Electrostatic interactions promote the self-assembled structure in the slurry, and after the drying process, bonding between the carbon matrix with the so-formed active material particles and the surface of the current collector is promoted by the surface treatment (e.g., functional groups on the matrix) and the strong entanglement of the active material in the carbon matrix.

[0109] As will be appreciated by those skilled in the art, the mechanical properties of the electrode can be easily modified depending on the application and mass loading requirements by tuning the surface functionalization versus the entanglement effect.

[0110] After coating and drying, the electrode undergoes a calendaring process to control the density and porosity of the active material. Densities of 3.5 g / cc or higher and porosities of 20% or higher can be achieved for NMC cathode electrodes. Depending on the mass loading and LIB cell requirements, the porosity can be optimized. For SiOx / Si anodes, the porosity is specifically controlled to accommodate the expansion of the active material during the lithiation process.

[0111] In some typical applications, the teachings herein can result in savings of up to 20% in $ / kWh. The use of a friendly solvent that evaporates easily allows for higher electrode throughput, and more importantly, significantly reduces energy consumption from long dryers. Conventional NMP recovery systems are also much simpler when alcohol or other solvent mixtures are used.

[0112] The teachings herein provide a 3D matrix that dramatically increases electrode conductivity by 10 to 100 times compared to electrodes using conventional binders such as PVDF, enabling rapid charging at the battery level. This technology enables thick electrode coatings on the cathode, up to 150 μm (or more) per side of the current collector. The solvent used in the slurry, combined with the strong 3D carbon matrix, is designed to achieve a thick wet coating without cracking during the drying process. The thick cathode with a high-capacity anode enables a substantial jump in energy density, reaching 400 Wh / kg or more.

[0113] One exemplary embodiment includes a Li-ion battery energy storage device in a pouch cell format that combines a Ni-rich NMC active material in the cathode and a SiOx and graphite blend active material in the anode, where both the anode and cathode are fabricated using the 3D carbon matrix process described herein.

[0114] A schematic diagram of the electrode arrangement of a pouch cell device is shown in Figure 3. As shown, a double-sided cathode 700, using cathode layers 760 (e.g., active layers according to various embodiments disclosed herein) on either side of an aluminum foil current collector 710, is disposed between two single-sided anodes 720 and 730, each having anode layers 740 and 750 (e.g., active layers comprising a network of carbon elements as disclosed herein) disposed on a copper foil current collector. The electrodes are separated by a permeable separator material (not shown) wetted with an electrolyte (not shown). This arrangement can be housed within a pouch cell of a type well known in the art.

[0115] 4 shows a cross section of an energy storage device (ESD) 810. The energy storage device (ESD) 810 includes a housing 811. The housing 811 has two terminals 800 disposed on its exterior. The terminals 800 provide an internal electrical connection to a storage cell 812 contained within the housing 811 and an external electrical connection to an external device, such as a load or charging device (not shown). The energy storage devices disclosed herein can be batteries, capacitors, ultracapacitors, etc.

[0116] The materials and structures disclosed herein are illustrated by the following non-limiting examples. [Example]

[0117] This is a prophetic example showing how an active anode material can be manufactured.

[0118] The anode can be formed from the following materials:

[0119] 27 to 31 weight percent (wt%) SiO—C and 1 to 5 wt% artificial graphite can be used as the anode active material. 2.2 to 2.7 wt% polyacrylic acid polymer and 0.1 to 0.5 wt% carboxymethyl cellulose can be used as the anode binder polymer. 0.0875 to 0.175 wt% single-walled carbon nanotubes and 0.35 to 0.4375 wt% multi-walled carbon nanotubes can be used as the conductive material. The remainder is made up of a water / ethanol (90 / 10 wt. ratio) solvent to form a 100% slurry. The slurry can be prepared and mixed as described above, coated onto a current collector, and dried to form an anode.

[0120] The cathode can be formed from the following materials:

[0121] Approximately 64 wt% Ni-rich NMC is used as the cathode active material. 0.1625-0.325 wt% polyamide or polyacrylic acid polymer and 0.1625-0.325 wt% polyvinylpyrrolidone are used as the cathode polymer binder. Multi-walled carbon nanotubes are used as the cathode conductive material in an amount of 0.325 wt%. Ethanol may be used as a solvent to make up the remainder of the slurry. The slurry can be prepared and mixed as described above, coated onto a current collector, and dried to form a cathode.

[0122] While the present invention has been described with reference to several embodiments, those skilled in the art will recognize that various changes can be made and equivalents can be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is not intended that the invention be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but rather that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. An electrode comprising an active layer, The active layer is a network of high aspect ratio carbon elements defining void spaces within the network; a plurality of electrode active material particles disposed in the voids within the network; a polymeric binder, the polymeric binder comprising a first polymer, a polyamide, or an acrylate polymer, comprising acid functional groups or salts of such acid functional groups, and a second polymer.

2. 10. The electrode of claim 1, wherein the network of high aspect ratio carbon elements comprises: a first set of carbon nanotubes, the first set of carbon nanotubes comprising a plurality of first carbon nanotubes or a plurality of bundles of first carbon nanotubes; a second set of carbon nanotubes; a second set of carbon nanotubes comprising a plurality of second carbon nanotubes or a plurality of bundles of second carbon nanotubes; An electrode, wherein the second set of carbon nanotubes has one or more properties that are different from the first set of carbon nanotubes.

3. The electrode of claim 2 , wherein the first set of carbon nanotubes comprises single-walled carbon nanotubes.

4. The electrode of claim 2 , wherein the second set of carbon nanotubes comprises multi-walled carbon nanotubes.

5. 3. The electrode of claim 2, the first set of carbon nanotubes comprises single-walled carbon nanotubes; the second set of carbon nanotubes comprises multi-walled carbon nanotubes; and an electrode wherein the weight ratio of the amount of the first set of carbon nanotubes to the second set of carbon nanotubes is about 2:1;

6. 2. The electrode of claim 1, wherein the network of high aspect ratio carbon elements comprises a set of multi-walled carbon nanotubes, preferably comprising 0.8 to 2.6 wt. %, more preferably 1 to 1.8 wt. % of multi-walled carbon nanotubes relative to the weight of the active layer.

7. 4. The electrode of claim 3, wherein the active layer comprises 0.2 to 0.6 wt. %, preferably 0.3 to 0.5 wt. % of single-walled carbon nanotubes relative to the weight of the active layer.

8. The electrode of any one of claims 1 to 7, wherein the second polymer comprises polyvinylpyrrolidone or a cellulose polymer.

9. 1. An energy storage device, comprising: Electrolytes, An energy storage device comprising the electrode according to any one of claims 1 to 8.

10. 10. The energy storage device of claim 9, wherein the electrode is the electrode of claim 5, and the multi-walled nanotubes swell more than the single-walled carbon nanotubes when wetted with the electrolyte.

11. 6. The electrode according to claim 5, wherein the multi-walled carbon nanotubes are: an average diameter of 6 nm to 10 nm; an average layer thickness of 6 nm to 7 nm, and The electrode has an average length of about 10 nanometers to 20 micrometers.

12. 6. The electrode according to claim 5, wherein the single-walled carbon nanotubes are: an average diameter of 0.5 nm to 5 nm, preferably 3 to 5 nm; The electrodes have an average length of about 10 nm to 20 micrometers, preferably 7 to 8 micrometers.

13. 6. The electrode according to claim 5, wherein the single-walled carbon nanotubes are: an average diameter of 3 nm to 5 nm, and An electrode having an average length of at least 200 micrometers.

14. 6. The electrode of claim 5, wherein the average thickness of the electrode increases by less than 10% after being wetted with electrolyte.

15. The electrode of claim 5 , wherein the average aspect ratio of the second set of carbon nanotubes is greater than the average aspect ratio of the first set of carbon nanotubes.

16. 1. An energy storage device, comprising: Housing and Electrolytes, a first current collector; an anode active material disposed on the first current collector, the anode active material comprising a network of high aspect ratio carbon elements defining void spaces within the network; a plurality of anode active material particles disposed in the void spaces within the network; an anode polymer binder, the anode polymer binder comprising a first polymer that is a polymer containing acid functional groups or salts of such acid functional groups, or an acrylate polymer; a second current collector; and a cathode active material disposed on the second current collector, the cathode active material comprising a network of high aspect ratio carbon elements defining void spaces within the network; and a plurality of cathode active material particles disposed in the void spaces within the network, the plurality of cathode active material particles comprising a combination of nickel, manganese, and cobalt; a cathode polymer binder, the cathode polymer binder comprising a first polymer that is a polymer containing acid functional groups or salts of such acid functional groups, a polyamide, or an acrylate polymer; 1. An energy storage device, wherein at least one of the anode polymer binder and the cathode polymer binder further comprises a second polymer.

17. 17. The energy storage device of claim 16, wherein the anode polymer binder comprises a second polymer, preferably a cellulose polymer, more preferably carboxymethyl cellulose.

18. 17. The energy storage device of claim 16, wherein the cathode polymer binder comprises a second polymer, preferably polyvinylpyrrolidone.

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