Electrode for energy storage device

Abstract

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

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of U.S. Patent Application No. 63 / 417,206, filed on October 18, 2022, which is hereby incorporated by reference in its entirety. Background of the Invention

[0003] Lithium batteries are used in many products, including medical devices, electric vehicles, airplanes, and consumer products (such as laptop computers, mobile phones, and cameras). Due to the high energy density, high operating voltage, and low self - discharge of lithium - ion batteries, they have replaced the secondary battery market and continue to find new uses in products and emerging industries.

[0004] Generally, a lithium - ion battery (“LIB” or “LiB”) includes an anode, a cathode, and an electrolyte material, such as an organic solvent containing a lithium salt. More specifically, a paste or slurry is formed by mixing an anode active material or a cathode active material with a binder and a solvent, and then the paste or slurry is coated on a current collector (such as aluminum or copper) and dried to form a film on the current collector, thereby forming the anode and the cathode (collectively referred to as “electrodes”). Then the anode and the cathode are layered or wound, and then placed into a pressurized housing containing the electrolyte material, and together they form a lithium - ion battery.

[0005] In conventional electrodes, a binder with sufficient adhesiveness and chemical properties is used such that the film coated on the current collector will remain in contact with the current collector even when it is manipulated for assembly into the pressurized battery housing. Since the film contains the electrode active material, if the film does not maintain sufficient contact with the current collector, there may be a significant interference with the electrochemical performance of the battery. In addition, it is important to select a binder that is mechanically compatible with the electrode active material such that it can withstand the degree of expansion and contraction of the electrode active material during charging and discharging of the battery.

[0006] Accordingly, binders such as cellulose binders or cross - linked polymer binders have been used to provide good mechanical properties. However, in conventional electrodes, the binders selected typically require environmentally unfriendly or toxic solvents for processing. Summary of the Invention

[0007] The present disclosure relates to an electrode, which includes an active layer that contains a network of high aspect ratio carbon elements defining interstitial spaces within the network; a plurality of electrode active material particles disposed within the interstitial spaces of the network; and a binder component that includes: a first polymer that includes an acid functional group or a salt of such acid functional group; a polyamide; or an acrylate polymer (such as in a polyacrylic acid latex), and a second polymer that is preferably selected from cellulose-based polymers and polyvinylpyrrolidone. The first polymer and the second polymer are present in the binder component as a blend of polymers. The first polymer and the second polymer are not covalently or ionically bonded to each other.

[0008] The present disclosure relates to an energy storage device that includes a housing; an electrolyte; a first current collector; an anode active material disposed on the first current collector; wherein the anode active material contains a network of high aspect ratio carbon elements defining interstitial spaces within the network; a plurality of anode active material particles disposed within the interstitial spaces of the network; and an anode polymer binder that includes: a first anode polymer that includes at least one polymer having an acid functional group or a salt of such acid functional group or a water-soluble acrylate polymer (such as in a polyacrylic acid latex), and optionally a second anode polymer that is preferably a cellulose-based polymer; and a second current collector; a cathode active material disposed on the second current collector; wherein the cathode active material contains a network of high aspect ratio carbon elements defining interstitial spaces within the network; a plurality of cathode active material particles disposed within the interstitial spaces of the network; wherein the cathode active material contains a combination of nickel, manganese, and cobalt; and a cathode polymer binder that includes: a first cathode polymer that includes at least one of the following: a polymer containing an acid functional group or a salt of such acid functional group; a polyamide; or an acrylate polymer (such as in a polyacrylic acid latex), and optionally a second cathode polymer that preferably includes polyvinylpyrrolidone, provided that at least one of the anode polymer binder and the cathode polymer binder contains the second polymer. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The following is a brief description of the drawings, where like elements are numbered alike and the drawings are presented for the purpose of illustrating the exemplary embodiments disclosed herein and not for the purpose of limiting the exemplary embodiments.

[0010] Figure 1 is an illustration of an electrode according to various embodiments;

[0011] Figure 2 is a flowchart of a method for preparing an electrode according to various embodiments;

[0012] Figure 3 is a depiction of an electrode arrangement of a pouch cell device; and

[0013] Figure 4 is a depiction of a schematic cross-sectional view showing aspects of an energy storage device (ESD). DETAILED DESCRIPTION

[0014] A more complete understanding of the components, processes, and devices disclosed herein can be obtained by reference to the accompanying drawings. These drawings are merely schematic representations for convenience and ease of demonstrating the disclosure and are therefore not intended to indicate the relative sizes and dimensions of the device or its 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 structure of the embodiments selected for illustration in the drawings and are not intended to define or limit the scope of the disclosure. In the drawings and the following description, it should be understood that like reference numerals denote like components.

[0015] Disclosed herein is an electrolyte cell including a housing that includes electrodes (an anode and a cathode). The housing includes an electrolyte that contacts the anode and the cathode. Both electrodes (the anode and the cathode) include current collectors having active layers disposed thereon. The active layer may be disposed on an optional adhesion layer that contacts the electrode.

[0016] Figure 1 is an illustration of an electrode (anode or cathode) according to various embodiments. In the illustrated example, electrode 100 is provided. According to various embodiments, electrode 100 includes current collector 102 and active layer 106. Electrode 100 may optionally include adhesion layer 104. As an example, adhesion layer 104 includes a material that promotes adhesion between current collector 102 and active layer 106.

[0017] Anode

[0018] In one embodiment, with respect to Figure 1, the electrode (anode or cathode) includes a current collector 102 as a conductive layer. For example, the current collector 102 can be a metal, a metal alloy, etc. 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 one embodiment, the current collector 102 has a thickness of 3 μm to 15 μm. In some preferred embodiments, the current collector 102 has a thickness between about 6 μm and 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.

[0019] The active layer 106 for 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 includes a second polymer. Note that, as contemplated herein, at least one of the anode and the cathode includes two polymers in its binder material.

[0020] The anode active material can include a first anode active material and optionally a second anode active material (the first anode active material and the second anode active material are collectively referred to as electrode active material particles). The active layer for the anode (anode active layer) is manufactured by mixing the first anode conductive material, the optional second anode conductive material, the first anode binder material, the optional second anode binder material, the first anode active material, and the optional second anode active material with a solvent to form a mixture. This mixing facilitates the 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 behind the solid active material. The mixture can be dispersed on the current collector or optionally on an adhesion 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 (including the solvent) and as a function of the solid anode active layer (excluding the solvent).

[0021] At least one of the first anode conductive material and the second anode conductive material is a high aspect ratio carbon element, which includes a substantially cylindrical network of carbon atoms. The first anode conductive material may comprise a first set of carbon nanotubes or multiple bundles of first carbon nanotubes, and the second anode conductive material comprises a second set of carbon nanotubes or multiple bundles of second carbon nanotubes. The first anode conductive material and the second anode conductive material are sometimes (individually and collectively) referred to herein as high aspect ratio carbon elements. In one embodiment, the term "high aspect ratio carbon element" refers to a carbon-containing element whose dimensions in one or more dimensions ("major dimensions") are significantly greater than its dimensions in the transverse dimension ("minor dimension").

[0022] The first anode conductive material and the second anode conductive material can form a conductive percolation network that can conduct current between any two separate points on the surface of a solid active layer (which contains no solvent). In other words, by means of physical contact or electron hopping between the first anode conductive material and the second anode conductive material in the anode active layer, current can be transmitted from one surface of the active layer to the opposite surface. The percolation network includes voids between the high aspect ratio carbon elements that accommodate the anode active materials (the first anode active material and the second anode active material).

[0023] In some embodiments, the anode active layer includes: (i) a network of high aspect ratio carbon elements that define void spaces within the network, (ii) a plurality of electrode active material particles disposed in the void spaces within the network, and (iii) a polymer binder, an anode polymer binder, which comprises: a first polymer, the first polymer comprising at least one polymer having an acid functional group or a salt of such an acid functional group or a water-soluble acrylate polymer (such as in a polyacrylic acid latex), and a second polymer, the second polymer preferably being a cellulose-based polymer. The first polymer and the second polymer are blended together to form the polymer binder. The first polymer and the second polymer are not covalently or ionically bonded to each other. A copolymer (a third polymer) that facilitates the blending of the first polymer and the second polymer can be used to make the first polymer and the second polymer compatible. The third polymer (copolymer) may comprise the first polymer and the second polymer bonded to each other. Thus, the third polymer serves as a surfactant to make the first polymer and the second polymer compatible.

[0024] The first anode conductive material can include high aspect ratio carbon elements defined by single carbon walls (SWCNTs). In one embodiment, the first anode conductive material includes single-walled carbon nanotubes. The outer diameter of the single-walled carbon nanotubes is from 0.5 nanometers to 5.0 nanometers, preferably from 1.0 nanometers to 3.5 nanometers. In one embodiment, the aspect ratio (length to diameter ratio) of the single-walled carbon nanotubes is 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 an exemplary embodiment, the single-walled carbon nanotubes have an average aspect ratio of 5 to 200.

[0025] In one embodiment, the single-walled carbon nanotubes can have a length 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, and more preferably greater than 15 micrometers up to at least 200 micrometers. In an exemplary embodiment, the single-walled carbon nanotubes have an average length of 10 nanometers to 20 micrometers, preferably 20 nanometers to 15 micrometers.

[0026] Based on the total weight of the mixture, the single-walled carbon nanotubes are present in the mixture (the mixture includes the first anode conductive material, the second anode conductive material, the first anode binder material, the second anode binder material, the first anode active material, the second anode active material, and a solvent) in an amount of 0.1 wt% to 0.3 wt%, preferably 0.15 wt% to 0.25 wt%.

[0027] Based on the total weight of the solid anode active material, the single-walled carbon nanotubes are present in the solid anode active material (the solid active material includes the first anode conductive material, the second anode conductive material, the first anode binder material, and the second anode binder material, without solvent) in an amount of 0.2 wt% to 0.6 wt%, preferably 0.3 wt% to 0.5 wt%.

[0028] The second anode conductive material can include high aspect ratio carbon elements defined by multiple carbon walls. In one embodiment, the second anode conductive material includes multi-walled carbon nanotubes (MWNTs). The number of carbon walls in the multi-walled carbon nanotubes can be 2 or more, 5 or more, 10 or more, 50 or more. According to various embodiments, the multi-walled carbon nanotubes include an average between 3 and 15 layers. In some embodiments, the multi-walled carbon nanotubes include an average between 4 and 12 layers. In some embodiments, the multi-walled carbon nanotubes include an average between 5 and 10 layers. In some embodiments, the multi-walled carbon nanotubes include an average between 6 and 7 layers. In some embodiments, the multi-walled carbon nanotubes include an average of at least 6 layers.

[0029] According to various embodiments, the active layer 106 includes multi-walled carbon nanotubes and single-walled carbon nanotubes. When the multi-walled carbon nanotubes and the single-walled carbon nanotubes are wetted by an electrolyte in an energy storage device having the electrode 100, the multi-walled carbon nanotubes swell more than the single-walled carbon nanotubes. In some embodiments, when the multi-walled carbon nanotubes and the single-walled carbon nanotubes are wetted by an electrolyte in an energy storage device having the electrode 100, the multi-walled carbon nanotubes swell at least 15% more than the single-walled carbon nanotubes. For example, when the multi-walled carbon nanotubes and the single-walled carbon nanotubes are wetted by an electrolyte, the length of the multi-walled carbon nanotubes expands at least 15% more than the length of the single-walled carbon nanotubes. In some embodiments, when the multi-walled carbon nanotubes and the single-walled carbon nanotubes are wetted by an electrolyte in an energy storage device having the electrode 100, the multi-walled carbon nanotubes swell at least 25% more than the single-walled carbon nanotubes. For example, when the multi-walled carbon nanotubes and the single-walled carbon nanotubes are wetted by an electrolyte, the length of the multi-walled carbon nanotubes expands at least 25% more than the length of the single-walled carbon nanotubes. In some embodiments, when the multi-walled carbon nanotubes and the single-walled carbon nanotubes are wetted by an electrolyte in an energy storage device having the electrode 100, the multi-walled carbon nanotubes swell at least 50% more than the single-walled carbon nanotubes. For example, when the multi-walled carbon nanotubes and the single-walled carbon nanotubes are wetted by an electrolyte, the length of the multi-walled carbon nanotubes expands at least 50% more than the length of the single-walled carbon nanotubes. In some embodiments, the multi-walled carbon nanotubes swell up to 50% when wetted (e.g., the length of the multi-walled carbon nanotubes is 50% greater after wetting with an electrolyte, and / or the diameter of the multi-walled carbon nanotubes is 50% greater after wetting, etc.).

[0030] According to various embodiments, the three-dimensional network of the high aspect ratio carbon element 108 includes carbon nanotubes, and the carbon nanotubes are only multi-walled carbon nanotubes and / or fragments of carbon nanotubes. For example, the three-dimensional network of the high aspect ratio carbon element 108 does not include single-walled carbon nanotubes or fragments of single-walled carbon nanotubes. According to various embodiments, the three-dimensional network of the high aspect ratio carbon element 108 includes at least 99 wt% carbon. In some embodiments, the three-dimensional network of the high aspect ratio carbon element 108 includes an electrically interconnected network of carbon elements that exhibits connectivity above the percolation threshold, and wherein 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 between any two points on any surface across the network.

[0031] The multi-walled carbon nanotubes have an outer diameter of 2.0 nanometers to 50 nanometers, preferably 5.0 nanometers to 40 nanometers, and more preferably 6 nanometers 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, and more preferably greater than 100, and more preferably greater than 500.

[0032] In one embodiment, 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, and more preferably greater than 15 micrometers. In an exemplary embodiment, the multi-walled carbon nanotubes have an average length of 10 nanometers to 20 micrometers, preferably 20 nanometers to 15 micrometers.

[0033] According to various embodiments, the electrodes include multi-walled carbon nanotubes that are relatively long compared to the multi-walled carbon nanotubes included in related art electrodes. The use of relatively long multi-walled carbon nanotubes in the electrodes has been found to have beneficial mechanical and / or electrical properties. For example, multi-walled carbon nanotubes provide relatively good power 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. Thus, using shorter multi-walled carbon nanotubes loses (or reduces) some beneficial properties associated with carbon nanotube swelling. As an extreme example, carbon black does not exhibit swelling because carbon black is merely particles of carbon without entanglement, such as the entanglement exhibited by a group of multi-walled carbon nanotubes. An indication that a quantity of multi-walled carbon nanotubes has a length that exceeds a threshold length and thus has sufficient swelling properties is the observation during the calendering process - calendering a relatively large amount of pressure or effort applied to the slurry associated with the foil indicates that the total swelling (e.g., average swelling) of the multi-walled carbon nanotubes in the active layer will meet a specific performance threshold. However, multi-walled carbon nanotubes are generally difficult to process. The processing of multi-walled carbon nanotubes related to preparing / forming the active layer and / or the electrodes is milder than the processes used for related art electrodes. Thus, the processes according to various embodiments preserve longer multi-walled carbon nanotubes (e.g., fewer multi-walled carbon nanotubes are crushed, broken, fractured, etc.). In some embodiments, the active layer of the electrode includes a group of multi-walled carbon nanotubes having an average length greater than the average length of the multi-walled carbon nanotubes in related art electrodes. According to various embodiments, the length distribution of the group of multi-walled carbon nanotubes is skewed towards multi-walled carbon nanotubes of a nominal length. As an example, the nominal length of the multi-walled carbon nanotubes is about 16 microns. For example, the multi-walled carbon nanotubes are processed and / or applied in a manner that reduces or minimizes the rupture or breakage of the multi-walled carbon nanotubes. The length of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements is typically the nominal length of the multi-walled carbon nanotubes, or the length of such multi-walled carbon nanotubes tends to be more severely skewed towards the nominal length. In some embodiments, at least 75% of the multi-walled carbon nanotubes within the network of high aspect ratio carbon elements are within 10% of the nominal length (e.g., between 13.4 microns and about 15 microns). In some embodiments, at least 75% of the multi-walled carbon nanotubes within the 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 within the 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 within the network of high aspect ratio carbon elements are within 10% of the nominal length (e.g., between 13.4 microns and about 15 microns). In some embodiments, at least 50% of the multi-walled carbon nanotubes within the 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 within the network of high aspect ratio carbon elements have a length of at least 8 microns.In some embodiments, at least 50% of the multi-walled carbon nanotubes within the network of high aspect ratio carbon elements have a length of at least 13 microns.

[0034] According to various embodiments, the length distribution of the set of multi-walled carbon nanotubes is skewed towards the multi-walled carbon nanotubes of the nominal length. For example, the multi-walled carbon nanotubes are processed and / or applied in a manner that reduces or minimizes the breakage or fracture of the multi-walled carbon nanotubes. The length of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements is typically the nominal length of the multi-walled carbon nanotubes, or the length of such multi-walled carbon nanotubes tends to be more severely skewed towards the nominal length.

[0035] In some embodiments, at least 75% of the multi-walled carbon nanotubes within the network of high aspect ratio carbon elements are within 10% of the nominal length (e.g., between 13.4 microns and about 15 microns). In some embodiments, at least 75% of the multi-walled carbon nanotubes within the 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 within the 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 within the network of high aspect ratio carbon elements are within 10% of the nominal length (e.g., between 13.4 microns and about 15 microns). In some embodiments, at least 50% of the multi-walled carbon nanotubes within the 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 within the network of high aspect ratio carbon elements have a length of at least 13 microns.

[0036] Based on the total weight of the mixture, the multi-walled carbon nanotubes are present in the mixture (the mixture contains a first anodic conductive material, a second anodic conductive material, a first anodic binder material, a second anodic binder material, and a solvent) in an amount of 0.3 wt% to 1.0 wt%, preferably 0.4 wt% to 0.9 wt%.

[0037] Based on the total weight of the solid anodic active material, the multi-walled carbon nanotubes are present in the solid anodic active material (the solid active material contains a first anodic conductive material, a second anodic conductive material, a first anodic binder material, and a second anodic binder material, without solvent) in an amount of 0.8 wt% to 2.6 wt%, preferably 1.0 wt% to 1.8 wt%.

[0038] In one embodiment, based on the weight of the corresponding conductive material, the second anodic conductive material is present in the mixture or the solid anodic active material layer in an amount of at least twice the amount of the first conductive material. In one embodiment, the ratio of the weight of the multi-walled carbon nanotubes to the weight of the single-walled carbon nanotubes in the mixture or the solid active material layer is at least 2:1.

[0039] The first anode binder comprises at least a first polymer soluble in water, alcohol or a combination thereof. Other solvents may be used together with water or alcohol. These will be described in detail later.

[0040] A suitable first polymer may be obtained by polymerization of a monomer having structure (1):

[0041]

[0042] 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 the first polymer obtained by polymerization of a monomer having structure (1) include polyacrylic acid, polymethacrylic acid, or a combination thereof. The first polymer has a molecular weight of 5,000 g / mol to 2,000,000 g / mol, preferably 10,000 g / mol to 1,000,000 g / mol, and may be a thermoplastic or cross-linked material.

[0043] The first polymer of the anode binder can be formed from 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.

[0044] The first anode binder can be modified by blending a first polymer (obtained by polymerization of a monomer having structure (1)) with a second polymer. Desirably, the blend of the first polymer and the second polymer is also soluble in water, alcohol, or a combination thereof. It is also contemplated that one or a portion of the first polymer or the second polymer is 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 polymer material. The second anode polymer can include an organic polymer selected from a variety of thermoplastic polymers. The second polymer can include an oligomer, a homopolymer, a copolymer, a block copolymer, an alternating block copolymer, a random polymer, a random copolymer, a random block copolymer, a graft copolymer, a star block copolymer, a dendrimer, a polyelectrolyte (a polymer having some repeating groups containing an electrolyte), a polyampholyte (a polyelectrolyte having both a cationic repeating group and an anionic repeating group), an 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 g / mole, preferably greater than 20,000 g / mole, and more preferably greater than 50,000 g / mole.

[0045] Examples of organic polymers including the second polymer include polyacetal, polyacrylic acid, polycarbonate, polyalkyd, polystyrene, polyolefin, polyester, polyamide, polyaramide, polyamideimide, polyarylate, polyurethane, epoxy resin, phenol, silicone, polyarylsulfone, polyethersulfone, polyphenylene sulfide, polysulfone, polyimide, polyetherimide, polytetrafluoroethylene, polyether ketone, polyetherether ketone, polyether ketone ketone, polybenzoxazole, polyoxadiazole, polybenzothiazinophenothiazine, polybenzothiazole, polypyrazinoquinoxaline, polyisophthalimide, polyquinoxaline, polybenzimidazole, polyoxindole, polyoxoisoindoline, polydioxoisoindoline, polytriazine, polyazine, polypiperazine, polypyridine, polypiperidine, polytriazole, polyazole, polycarborane, polyoxabicyclononane, polydibenzofuran, polystyphnate, polyacetal, polyanhydride, polyethylene ether, polyethylene sulfide, 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 combinations thereof.

[0046] In a preferred embodiment, the second polymer is preferably soluble in water, alcohol, or combinations thereof. The second polymer can be polyacrylamide, polyamide, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, a cellulose-based polymer, an acrylic / maleic acid copolymer, a polyoligosaccharide, or combinations thereof. In a preferred embodiment, the second polymer of the anode polymer is a cellulose-based polymer.

[0047] The first polymer of the anode binder can be a derivative of the first polymer obtained by polymerizing the monomer of structure (1). In one embodiment, the derivative can include a salt of the first polymer. Examples of salts of the first polymer include the tetradecyldimethylbenzylammonium salt of polyacrylic acid, the benzethonium salt of polyacrylic acid, or other salts of polyacrylic acid.

[0048] Based on the total weight of the mixture (where the mixture comprises 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, and a second anode active material, as well as a solvent), the first anode polymer may be present in an amount of from 2 wt% to 3 wt%, preferably from 2.1 wt% to 2.9 wt%. Based on the total weight of the solid active layer, the first anode polymer may be present in an amount of from 5 wt% to 9 wt%, preferably from 6 wt% to 8 wt%.

[0049] The second anode polymer present in the active layer is preferably also a water-soluble polymer. The second anode binder is chemically different from the first anode polymer. In one embodiment, the second anode polymer may be a naturally occurring water-soluble polymer. Examples of naturally occurring polymers used as the second anode binder include cellulose and cellulose derivatives (e.g., hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose (CMC), sodium carboxymethylcellulose, cellulose acetate, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose acetate butyrate, and cellulose ethers such as ethylcellulose, etc., or combinations thereof), sugars (glucose, sucrose, lactose, galactose, fructose, mannitol, sorbitol, or combinations thereof), ion complexes of cellulose (gums (e.g., gum arabic, alginate, carrageenan, guar gum, tragacanth gum, pectin, ghatti gum, xanthan gum, etc., or combinations thereof).

[0050] Other examples of the second anode polymer include poly(ethylene oxide) (PEO), polyethers, derivatives of poly(ethylene glycol) (PEG), fluoropolymers especially poly(vinylidene fluoride) (PVDF), polyurethanes (PU), polytetrafluoroethylene (PTFE), alginates (Alg), renatured DNA / Alg, Alg-catechol, poly(acrylic 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 helix native xanthan gum, Li-Nafion, PAA / CMC, crosslinked PAA / PVA, glycerol-crosslinked PEDOT:PSS, maleic anhydride (MAH)-crosslinked corn starch, MAH-crosslinked CMC, crosslinked native GG polymer, crosslinked chitosan, CS-CG+GA, crosslinked dextran, crosslinked CMC-PEG, crosslinked hyperbranched PEI, crosslinked PAM gel, 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 gel, (Fe 3+ ) crosslinked (PANa 0.8 Fe y ), Sn 4+ crosslinked PEDOT:PSS, PAA-PEG-PBI, crosslinked CMC-CPAM, metal polymers, Si@Fe 3+ -PDA-PAA, β-CDp / 6AD, slip-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 adhesives, 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), copolymers of any of the foregoing subsets.

[0051] In a preferred embodiment, the second anode polymer comprises or consists of carboxymethyl cellulose (CMC).

[0052] Based on the total weight of the mixture, the second anode polymer can be present in an amount of 0.1 wt% to 1.0 wt%, preferably 0.2 wt% to 0.6 wt%. Based on the total weight of the solid active layer, the second anode binder can be present in an amount of 0.2 wt% to 2 wt%, preferably 0.4 wt% to 1.6 wt%.

[0053] In one embodiment, if the first anode polymer and the second anode polymer are not mutually compatible, they can be blended together with a third polymer that comprises a copolymer having two components - where one component (the first component) is compatible with the first anode polymer and where the second component is compatible with the second anode polymer.

[0054] The anode active material can be located in voids surrounded by a conductive network formed by 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 it has a higher capacity and longer cycle life than 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. Using carbon-coated silicon monoxide provides a high-capacity anode for the storage device that exhibits an initial Coulombic efficiency (ICE) greater than 90%.

[0055] Based on the total weight of the mixture, the first anode active material is present in the mixture in an amount of 25 wt% to 33 wt%, preferably 26 wt% to 31 wt% (where the mixture is the first anode conductive material, the second anode conductive material, the first anode binder material, the second anode binder material, the first anode active material, the second anode active material, and the solvent).

[0056] Based on the total weight of the anode active layer, the first anode active material is present in the anode active layer in an amount of 67 wt% to 95 wt%.

[0057] 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 particulate form (powder form). In one embodiment, the graphite can be intercalated.

[0058] Based on the total weight of the mixture, the graphite can be added in an amount of 0.75 wt% to 6 wt%, preferably 1 wt% to 5 wt%. Based on the total weight of the solid active layer, the graphite can be added in an amount of 2.5 wt% to 18 wt%, preferably 4 wt% to 16 wt%.

[0059] In one embodiment, an electrode based on a SiOx / graphite anode (SiOx content = about 20 wt%) and a method for synthesizing and manufacturing the same: a mass loading of 8 mg / cm 2 to 14 mg / cm 2 , with a reversible specific capacity ≥ 550 mAh / g. In particular, the long-life performance of a Li-ion-based electrolyte based on a SiOx / graphite anode for a battery: -30°C to 60°C. A pouch cell of a Ni-rich NMC cathode / SiOx + graphite / carbon / Li-ion-based battery with high energy, high power density, and long cycle life: a capacity ≥ 5 Ah, a specific energy ≥ 300 Wh / kg, an energy density ≥ 800 Wh / L, a cycle life exceeding 500 cycles at a 1C rate of charge-discharge, and an ultra-high power fast charge-discharge C rate (up to 5C rate) capability.

[0060] The mixture for manufacturing the anode active layer further contains a solvent. The solvent is preferably a solvent for dispersing the first anode polymer, the second anode polymer, the first anode conductive material, and the second conductive material to form a mixture. Then the mixture is disposed on a current collector to form an active layer.

[0061] Suitable solvents are water, alcohols, or a combination thereof. Examples of alcohols are ethanol, methanol, propanol, butanol, ethylene glycol, propylene glycol, or a combination thereof. In addition to water and alcohols, other solvents can be added to facilitate the dissolution and / or dispersion of the polymer. Other solvents include polar solvents, non-polar solvents, etc. The addition of other solvents should preferably not change the solubility of the polymer in water or alcohols. Liquid aprotic polar solvents such as propylene carbonate, ethylene carbonate, butyrolactone, acetonitrile, benzonitrile, nitromethane, nitrobenzene, sulfolane, dimethylformamide, N-methylpyrrolidone, etc., or a combination thereof can be added to water or alcohols to dissolve the polymer. Polar protic solvents such as acetonitrile, nitromethane, acetone, dimethyl sulfoxide, dimethylformamide, etc., or a combination thereof can be used. Other non-polar solvents such as benzene, toluene, dichloromethane, carbon tetrachloride, hexane, ether, tetrahydrofuran, etc., or a combination thereof can also be used. A co-solvent including at least one aprotic polar solvent and at least one non-polar solvent can also be used to change the dissolution ability of the solvent.

[0062] When water and alcohols are used as solvents for the active layer (for the anode), the ratio of water to alcohols is 80:20 to 95:5, preferably 88:12 to 92:8. In an exemplary embodiment, the ratio of water to alcohols is 90:10.

[0063] Based on the total weight of the mixture, the solvent is present in an amount of 60 wt% to 95 wt%, preferably 65 wt% to 90 wt%. The solid active layer preferably does not contain solvents (water and alcohols).

[0064] 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.

[0065] According to various embodiments, the active layer 106 swells (e.g., expands) 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.

[0066] The mixture comprising the binder, the conductive material, and the solvent may further comprise additional additives such as dispersants, surfactants, etc. or combinations thereof. Surfactants and dispersants are used to provide a surfactant layer on the high aspect ratio carbon element.

[0067] The surface treatment may include a surfactant layer that bonds to the high aspect ratio carbon element 108 and comprises a plurality of surfactant elements, each surfactant element having a hydrophobic end and a hydrophilic end, wherein the hydrophobic end is disposed proximal to the surface of one of the high aspect ratio carbon elements in the high aspect ratio carbon element 108, and the hydrophilic end is disposed distal to the surface of one of the high aspect ratio carbon elements in the high aspect ratio carbon element 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 that is soluble in a solvent having a boiling point below 200 °C. In some embodiments, the surface treatment includes a material that is soluble in a solvent having a boiling point below 185 °C.

[0068] According to various embodiments, the active layer 106 comprises a polymer that can be used as a dispersant. The dispersant can be selected based on its compatibility with water and / or an alcohol (such as ethanol). In some embodiments, the dispersant is a water-soluble polymer. In some embodiments, the dispersant corresponds to or comprises polyvinylpyrrolidone (PVP). The PVP used in the dispersant can be a PVP having a relatively high molecular weight.

[0069] According to various embodiments, the active layer 106 comprises about 25 wt% of the dispersant based on the active layer 106. In some embodiments, the amount of the dispersant comprised in the active layer 106 is between 10 wt% and 50 wt% of the active layer 106. In some embodiments, the amount of the dispersant comprised in the active layer 106 is between 15 wt% and 40 wt% of the active layer 106. In some embodiments, the amount of the dispersant comprised in the active layer 106 is between 20 wt% and 30 wt% of the active layer 106.

[0070] In various embodiments, the surfactant for forming the surface treatment comprises one or more of the following: cetyltrimethylammonium hexafluorophosphate (CTAP), cetyltrimethylammonium tetrafluoroborate (CTAB), cetyltrimethylammonium acetate, cetyltrimethylammonium nitrate, cocamidopropyl betaine, N-(cocoalkyl)-N,N,N-trimethylammonium methyl sulfate, cocamidopropyl betaine, etc. or combinations thereof.

[0071] Cathode

[0072] The cathode comprises one or more polymer binders (cathode polymer binders), one or more active materials, and a conductive material. One or more polymer binders, one or more active materials, and a conductive material are blended with a solvent to form a cathode mixture. The cathode mixture is then disposed on a current collector (usually metal) and dried to form a solid cathode active layer.

[0073] As described above, the polymer binder for at least one of the anode and cathode comprises two polymers. Thus, the cathode polymer binder (for use in the cathode) can comprise a first cathode polymer that comprises an acid functional group or a salt of such an acid functional group; a polyamide; or an acrylate polymer (such as in polyacrylic acid latex). The cathode polymer binder (for use in the cathode) preferably further comprises a second cathode polymer. The second cathode polymer preferably comprises polyvinylpyrrolidone (PVP).

[0074] The polyamide (for use 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 employed singly or in combination: Nylon-6 and nylon-6,6 are suitable polyamide resins available from various commercial sources. However, other polyamides can also be used, 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 (PA610), nylon 11 (PA11), nylon 12 (PA 12), nylon 6-3-T (PA 6-3-T), polyarylamide (PA MXD 6), polyphthalamide (PPA), and / or polyether block amide, as well as other polyamides such as amorphous nylon. Mixtures of various polyamides and various polyamide copolymers are also available.

[0075] Polyamides can be obtained by many well-known methods, such as those described in the following patents: U.S. Patent Nos. 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 the polymerization product of caprolactam. Nylon-6,6 is the condensation product of adipic acid and 1,6-diaminohexane. Similarly, nylon 4,6 is the condensation product between adipic acid and 1,4-diaminobutane. In addition to adipic acid, other available diacids for preparing nylon include azelaic acid, sebacic acid, dodecanedioic acid, and terephthalic acid and isophthalic acid, etc. Other available diamines include m-xylenediamine, bis-(4-aminophenyl)methane, bis-(4-aminocyclohexyl)methane; 2,2-bis-(4-aminophenyl)propane, 2,2-bis-(4-aminocyclohexyl)propane, etc. Copolymers of caprolactam with diacids and diamines are also available.

[0076] Polyamides are generally derived from the polymerization of organic lactams having 4 to 12 carbon atoms. In one embodiment, the lactam is represented by formula (I)

[0077]

[0078] wherein n is from 3 to 11. In one embodiment, the lactam is ε-caprolactam where n is equal to 5.

[0079] Polyamides can also be synthesized from amino acids having 4 to 12 carbon atoms. In one embodiment, the amino acid is represented by formula (II)

[0080]

[0081] wherein n is from 3 to 11. In one embodiment, the amino acid is ε-aminohexanoic acid where n is equal to 5. Polyamides can also be formed by polymerizing 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)

[0082] H2N-(CH2) n —NH2(III)

[0083] Where 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 the dicarboxylic acid to the diamine is from 0.66 to 1.5. Within this range, it is generally beneficial to have a molar ratio greater than or equal to 0.81. In another embodiment, the molar ratio is greater than or equal to 0.96. In yet another embodiment, the molar ratio is less than or equal to 1.22. In still another embodiment, the molar ratio is less than or equal to 1.04. Examples of polyamides useful in the present invention include nylon 6, nylon 6,6, nylon 4,6, nylon 6,12, nylon 10, or combinations comprising at least one of the foregoing polyamides.

[0084] The acid-functional cathode polymer can comprise polyacrylic acid, a polyacrylic acid copolymer, or combinations thereof, which are listed and described above and will not be repeated here for the sake of brevity.

[0085] The acrylate copolymer comprises a polyacrylate or polymethacrylate copolymerized with another polymer that does not have the exact chemical structure of a polyacrylate or polymethacrylate. The acrylate can be obtained by polymerization of monomers having a structure represented by formula (4) or by formula (5):

[0086]

[0087] 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 7-10 arylalkyl group. In one embodiment, the polyacrylate comprises a fluorine atom and is obtained by polymerization of a monomer having at least one fluorine atom substituent and having a structure represented by formula (5):

[0088]

[0089] where R1 is hydrogen or an alkyl group having 1 to 10 carbon atoms, and R3 is C 2-10 fluoroalkyl group. Suitable polymeric acrylates include polyacrylate, polymethyl acrylate, polymethyl methacrylate, polybutyl acrylate, or combinations thereof.

[0090] In one embodiment, polyacrylic acid (detailed above) is copolymerized with polyamide (detailed above) or with a polyacrylate (detailed above) to form a first cathode polymer binder.

[0091] Based on the weight of the cathode mixture, which comprises a cathode polymer binder (a first cathode polymer binder and a second cathode polymer binder), a cathode active material, a cathode conductive material, and a solvent, the first cathode polymer binder is present in an amount of 0.1 wt% to 0.4 wt%, preferably 0.15 wt% to 0.375 wt%. Based on the total weight of the cathode active layer, the first cathode polymer binder is present in the cathode active layer in an amount of 0.2 wt% to 0.5 wt%, preferably 0.25 wt% to 0.45 wt%.

[0092] The cathode active layer preferably comprises a second cathode polymer binder, which comprises polyvinylpyrrolidone (PVP). In addition to acting as the second cathode polymer binder, PVP can also be used as a dispersant for the cathode active material and the cathode conductive filler.

[0093] Based on the weight of the cathode mixture, which comprises a cathode polymer binder (a first cathode polymer binder and a second cathode polymer binder), a cathode active material, a cathode conductive material, and a solvent, the second cathode polymer binder is present in an amount of 0.1 wt% to 0.4 wt%, preferably 0.15 wt% to 0.375 wt%. Based on the total weight of the cathode active layer, the second cathode polymer binder is present in the cathode active layer in an amount of 0.2 wt% to 0.5 wt%, preferably 0.25 wt% to 0.45 wt%.

[0094] The cathode mixture comprises a conductive material. The conductive material can comprise a high aspect ratio carbon element. The high aspect ratio carbon element comprises single-walled carbon nanotubes, multi-walled carbon nanotubes, or a combination thereof as discussed above. For example, the cathode conductive material can comprise multi-walled carbon nanotubes, forming a percolation network having voids encapsulated by the multi-walled carbon nanotubes. The voids comprise the cathode active material. The multi-walled carbon nanotubes are described in detail above and will not be described in detail again for the sake of brevity. Based on the weight of the cathode mixture, which comprises a cathode polymer binder (a first cathode polymer binder and a second cathode polymer binder), a cathode active material, a cathode conductive material, and a solvent, the multi-walled carbon nanotubes are present in an amount of 0.1 wt% to 0.5 wt%, preferably 0.2 wt% to 0.4 wt%. Based on the total weight of the cathode active layer, the multi-walled carbon nanotubes are present in the cathode active layer in an amount of 0.2 wt% to 0.7 wt%, preferably 0.3 wt% to 0.6 wt%.

[0095] The cathode active material may comprise a nickel-rich combination of nickel, manganese, and cobalt. Lithium-nickel-manganese-cobalt-oxide (LiNiMnCoO2), abbreviated as NMC, provides strong overall performance, excellent specific energy, and the lowest self-heating rate among all mainstream cathode powders. Based on the total weight of the NMC blend, the NMC powder may comprise nickel in an amount of 20 wt% to 40 wt%, manganese in an amount of 20 wt% to 40 wt%, and cobalt in an amount of 20 wt% to 40 wt%. While the term "NMC powder" may refer to a variety of blends, it is desirable to use a blend comprising 33 wt% nickel, 33 wt% manganese, and 33 wt% cobalt. This blend (sometimes referred to as 1-1-1) is useful for applications (automotive, energy storage) that use frequent cycling because of the reduced material cost achieved by the lower cobalt content.

[0096] As described above, the cathode active material is accommodated within a network of high aspect ratio active material present in the cathode active layer. Based on the total weight of the cathode mixture (the mixture used to make the cathode active layer, which comprises a cathode polymer binder (a first cathode polymer binder and a second cathode polymer binder), a cathode active material, a cathode conductive material, and a solvent), the cathode active material is present in an amount of 55 wt% to 75 wt%, preferably 60 wt% to 70 wt%. Based on the total weight of the cathode active layer, the cathode active material is present in the cathode active layer (which is solvent-free) in an amount of 95 wt% to 98.5 wt%.

[0097] In one embodiment, a cathode polymer binder (a first cathode polymer and a second cathode polymer), a cathode active material, a cathode conductive material are blended with a solvent to form a cathode mixture in the form of a slurry. This can occur in a single step, or can first include an initial slurry of the cathode conductive material and at least a portion of one cathode polymer, and then the initial slurry is further mixed with the cathode active material and any remaining portion of the cathode polymer. The blending process facilitates the dispersion of the cathode conductive material and the cathode active material to form a percolation network through the volume of the cathode active layer upon removal of the solvent. In one embodiment, after mixing is complete, the cathode mixture (in slurry form) is disposed on a current collector. The current collector on which the cathode mixture is disposed is sheared and compressed in a roll mill. The use of the roll mill facilitates the bonding of the cathode active layer to the current collector.

[0098] Figure 2 is a flow chart of a method of preparing an electrode according to various embodiments. Regarding Figure 1 of the electrode 100 provides a description of the process 600. Referring to Figure 2, in some embodiments, the active layer 106 of the electrode 100 can be formed using process 600. At 610, a high aspect ratio carbon element and a surface treatment material (e.g., a surfactant or a polymeric material as described herein) are combined with a solvent (of the type described herein) to form an initial slurry.

[0099] At 620, the initial slurry is processed to ensure good dispersion of the solid materials in the slurry. In some embodiments, the processing includes introducing mechanical energy into the mixture of the solvent and the solid materials (e.g., using an ultrasonic device, which may sometimes also be referred to as an “ultrasonic”) or other suitable mixing devices (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 greater. For example, the mechanical energy introduced into the mixture per kilogram of the mixture can be in the range of 0.4 kWh / kg to 1.0 kWh / kg or any sub-range thereof, such as 0.4 kWh / kg to 0.6 kWh / kg.

[0100] In some embodiments, an ultrasonic bath mixer can be used. In other embodiments, a probe ultrasonic device can be used. When compared to an ultrasonic bath used for nanoparticle applications, probe sonication can be significantly more powerful and effective. The high shear forces generated by ultrasonic cavitation have the ability to break up particle agglomerates and produce smaller and more uniform particle sizes. In addition to this, sonication can achieve a stable and uniform suspension of the solids in the slurry. Generally, this causes dispersion and depolymerization of the solids and other breakdown. Examples of probe sonication devices include the Q-Series probe ultrasonic devices that can be commercially obtained from QSonica LLC, Newtown, Connecticut. Another example includes the Branson Digital SFX-450 ultrasonic device that can be commercially obtained from Thomas Scientific, Swedesboro, New Jersey.

[0101] However, in some embodiments, the local nature of each probe within the probe assembly can lead to non-uniform mixing and suspension. This may be the case for, for example, large sample scenarios. This can be addressed by using a setup with a continuous flow cell and proper mixing. For example, with such a setup, mixing of the slurry will achieve a reasonably uniform dispersion.

[0102] In some embodiments, once processed, the initial slurry will have a viscosity in the range of 5,000 cps to 25,000 cps or any sub-range thereof (e.g., 6,000 cps to 19,000 cps).

[0103] At 630, the surface treatment can be formed, either fully or in part, on the high aspect ratio carbon elements in the initial slurry. In some embodiments, at this stage, the surface treatment can self-assemble. The resulting surface treatment can include functional groups or other features, as described in further steps below, which can promote adhesion between the high aspect ratio carbon elements and the active material particles.

[0104] At 640, the active material particles can be combined with the initial slurry to form a final slurry that contains the active material particles along with the high aspect ratio carbon elements on which the surface treatment has been formed.

[0105] In some embodiments, the active material can be added directly to the initial slurry. In other embodiments, the active material can first be dispersed in a solvent (e.g., using the techniques described above with respect to the initial solvent) to form an active material slurry. Then, the active material slurry can be combined with the initial slurry to form the final slurry.

[0106] 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 can be used. In some embodiments, the processing can use the techniques described above with reference to 620. In some embodiments, a planetary mixer such as a multi-axis (e.g., three-axis or more) planetary mixer can be used. In some such embodiments, the planetary mixer can be characterized by multiple blades, e.g., two or more mixing blades and one or more (e.g., two, three, or more) dispersion blades such as disk dispersion blades.

[0107] In some embodiments, during 650, the matrix that enwraps the active material can self-assemble either fully or in part. In some embodiments, the interaction between the surface treatment and the active material promotes the self-assembly process.

[0108] In some embodiments, once processed, the final slurry will have a viscosity in the range of 1,000 cps to 10,000 cps or any sub-range thereof (e.g., 2,500 cps to 6000 cps).

[0109] At 660, the active layer 106 is formed from the final slurry. In some embodiments, the final slurry can be directly wet cast onto the current collector conductive layer 102 (or optional adhesion layer 104) and dried. As an example, casting can be performed by applying at least one of heat and vacuum until substantially all of the solvent and any other liquid has been removed, thereby forming the active layer 106. In some such embodiments, it may be desirable to protect various portions of the underlying layer. For example, in cases where the electrode 100 is intended for dual-sided operation, it may be desirable to protect the underside of the conductive layer 102. Protection can include, for example, protecting from solvents by masking certain areas or providing a drainage device to direct the solvent away.

[0110] In other embodiments, the final slurry can be at least partially dried elsewhere and then transferred onto the adhesion layer 104 or conductive layer 102 using any suitable technique (e.g., roll-to-roll layer application) to form the active layer 106. In some embodiments, the wet combined slurry can be placed on an intermediate material having a suitable surface and dried to form a layer (e.g., the active layer 106). Although any material having a suitable surface can be used as the intermediate material, exemplary intermediate materials include PTFE because its properties facilitate subsequent removal from the surface. In some embodiments, the specified layer is formed in a press to provide a layer exhibiting the desired thickness, area, and density.

[0111] In some embodiments, the final slurry can be formed into a sheet and appropriately coated onto the adhesion layer 104 or conductive layer 102. For example, in some embodiments, the final slurry can be applied by a slot die to control the thickness of the applied layer. In other embodiments, the slurry can be applied and then, for example, leveled to the desired thickness using a doctor blade. A variety of other techniques can be used to apply the slurry. For example, coating techniques can include, but are not limited to: comma coating; reverse comma coating; doctor blade coating; slot die coating; direct gravure coating; air knife coating; chamber doctor blade coating; displacement gravure coating; single-pass roll kiss coating; reverse kiss coating with a small diameter gravure roll; rod coating; three-pass reverse roll coating (top feed); three-pass reverse roll coating (feed die); reverse roll coating, etc.

[0112] The viscosity of the final slurry can vary depending on the application technique. For example, for comma coating, the viscosity can be in the range of about 1,000 cps to about 200,000 cps. Lip die coating provides coating of slurries having a viscosity of about 500 cps to about 300,000 cps. Reverse kiss coating provides coating of slurries having a viscosity between about 5 cps and 1,000 cps. In some applications, the corresponding layer can be formed by multiple passes.

[0113] In some embodiments, the active layer 106 formed from the final slurry can be compressed (e.g., using a calendering device) before or after being applied to the electrode 100. In some embodiments, the slurry is partially or fully 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 can be compressed to a final thickness that is less than 90%, 80%, 70%, 50%, 40%, 30%, 20%, 10%, or less of its thickness before compression (e.g., in a direction perpendicular to the current collector layer 102).

[0114] In various embodiments, when a partially dried layer is formed during the coating or compression process, the layer can subsequently be fully 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.

[0115] In some embodiments, the solvent used to form the slurry is recovered and recycled into the slurry preparation process.

[0116] In some embodiments, the active layer 106 can be compressed, for example, to break some of the high aspect ratio carbon elements or other carbon-containing materials of the composition to increase the surface area of the corresponding layer. In some embodiments, such a compression treatment can increase one or more of the adhesion between layers, the ion transport rate within the layer, and the surface area of the layer. In various embodiments, compression can be applied before or after applying or forming the corresponding layer on the electrode 100.

[0117] In some embodiments where calendering is used to compress the active layer 106, the calendering device can be set to a gap spacing equal to less than 90%, 80%, 70%, 50%, 40%, 30%, 20%, 10%, or less of the thickness of the layer before compression (e.g., set to approximately 33% of the thickness of the layer before compression). The calendering rolls can be configured to provide a suitable pressure, such as greater than 1 ton / cm of roll length, greater than 1.5 tons / cm of roll length, greater than 2.0 tons / cm of roll length, greater than 2.5 tons / cm of roll length, or greater. In some embodiments, the active layer after compression will have a density in the range of 1 g / cc to 10 g / cc or any sub-range thereof (such as 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 sub-range thereof. In some embodiments, the active layer 106 can be preheated (e.g., at a temperature in the range of 20°C to 100°C or any sub-range thereof) before calendering.

[0118] Once the electrode 100 has been assembled, the electrode 100 can be used to assemble an energy storage device. The assembly of the energy storage device can follow conventional steps for assembling the electrode with a separator and placing it within a housing (e.g., a can or a pouch), and can also include additional steps for adding an electrolyte and sealing the housing.

[0119] In various embodiments, process 600 can include any one of the following features, either individually or in any suitable combination.

[0120] In some embodiments, the initial slurry has a solids content in the range of from 0.1% to 20.0% (or any sub-range thereof) by weight. In some embodiments, the final slurry has a solids content in the range of from 10.0% to 80% (or any sub-range thereof) by weight.

[0121] The 3D carbon scaffold or matrix holds the active material particles together to form a cohesive layer that is also firmly attached to the metal current collector. This active material structure is generated during the slurry preparation process and subsequently during the roll-to-roll (“R2R”) coating and drying processes. 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.

[0122] A 3D carbon matrix is formed during slurry preparation using the techniques described herein: a high aspect ratio carbon material is suitably dispersed and chemically functionalized using, for example, a two-step slurry preparation process (such as the type described above with reference to Figure 2 process 600). The chemical functionalization is designed to form an organized self-assembled structure with the surface of the active material particles (e.g., NMC particles for the cathode, or Si particles (“Si”) or silicon oxide (“SiOx”) particles in the case of the anode). The slurry so formed can be based on water and / or alcohol solvents for the cathode and water for the anode, and such solvents are very easy to evaporate and handle during the manufacturing process. Electrostatic interactions promote the self-organized structure in the slurry, and after the drying process, the binding between the carbon matrix with the active material particles so formed and the surface of the current collector is promoted by surface treatment (e.g., functional groups on the matrix) and strong entanglement of the active material in the carbon matrix.

[0123] As will be understood by those skilled in the art, by modulating the surface functionalization to the entanglement effect, the mechanical properties of the electrode can be readily altered according to the application and mass loading requirements.

[0124] After coating and drying, the electrodes undergo a calendaring step to control the density and porosity of the active material. In NMC cathode electrodes, a density of 3.5 g / cc or greater and a porosity of 20% or greater can be achieved. The porosity can be optimized based on the mass loading and LIB cell requirements. As for SiOx / Si anodes, the porosity is specifically controlled to accommodate the swelling of the active material during the lithiation process.

[0125] In some typical applications, the teachings herein can provide up to a 20% reduction in $ / kWh. By using easily evaporable friendly solvents, the electrode yield is higher, and more importantly, the energy consumption of the long dryer is significantly reduced. When using alcohols or other solvent mixtures, the conventional NMP recovery system is also greatly simplified.

[0126] The teachings herein provide a 3D matrix that significantly increases the electrode conductivity by 10 to 100 times compared to electrodes using conventional binders such as PVDF, which enables fast charging at the cell level. Using this technology, thick electrode coatings in the cathode can reach 150 μm (or more) on each side of the current collector. The solvent designed for use in the slurry in combination with the strong 3D carbon matrix is capable of achieving thick wet coatings without cracking during the drying step. A thick cathode with a high-capacity anode enables a significant jump in energy density to 400 Wh / kg or higher.

[0127] An exemplary embodiment includes a lithium-ion battery energy storage device in the form of a pouch cell that combines a Ni-rich NMC active material in the cathode with a SiOx and graphite blend active material in the anode, where both the anode and cathode are fabricated using the 3D carbon matrix process as described herein.

[0128] Figure 3 A schematic illustration of the electrode arrangement of the pouch cell device is shown. As shown, a double-sided cathode 700 using a cathode layer 760 (e.g., an active layer according to various embodiments disclosed herein) is disposed between two single-sided anodes 720 and 730 on opposite sides of an aluminum foil current collector 710, each single-sided anode having an anode layer 740 and 750 (e.g., an active layer including a carbon element network such as disclosed herein) disposed on a copper foil current collector. The electrodes are separated by a permeable separator material (not shown) wetted by an electrolyte (not shown). This arrangement can be housed in a pouch cell of a type known in the art.

[0129] In Figure 4In it, a cross-section of an energy storage device (ESD) 810 is shown. 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 element 812 housed within the housing 811 and an external electrical connection to an external device such as a load or a charging device (not shown). The energy storage device disclosed herein can be a battery, a capacitor, a supercapacitor, etc.

[0130] The materials and structures disclosed herein are illustrated by the following non-limiting examples.

[0131] Example

[0132] This is a hypothetical embodiment describing how to fabricate an active anode material.

[0133] The anode can be formed from the following materials:

[0134] 27 wt% to 31 wt% of SiO-C and 1 wt% to 5 wt% of artificial graphite can be used as the anode active material. 2.2 wt% to 2.7 wt% of polyacrylic acid polymer and 0.1 wt% to 0.5 wt% of carboxymethyl cellulose can be used as the anode binder polymer. 0.0875 wt% to 0.175 wt% of single-walled carbon nanotubes and 0.35 wt% to 0.4375 wt% of multi-walled carbon nanotubes can be used as the conductive material. A water / ethanol (90 / 10 weight ratio) solvent makes up the remainder to produce 100% to form a slurry. The slurry can be prepared and mixed as described above, and coated onto a current collector and dried to form the anode.

[0135] The cathode can be formed from the following materials:

[0136] Approximately 64 wt% of Ni-rich NMC as the cathode active material. 0.1625 wt% to 0.325 wt% of polyamide or polyacrylic acid polymer and 0.1625 wt% to 0.325 wt% of polyvinylpyrrolidone are used as the cathode polymer binder. Multi-walled carbon nanotubes will be used as the cathode conductive material in an amount of 0.325 wt%. Ethanol can be used as the solvent to make up the remainder of the slurry. The slurry can be prepared and mixed as described above, and coated onto a current collector and dried to form the cathode.

[0137] Although the present invention has been described with reference to some embodiments, those skilled in the art will understand that various changes can be made and elements thereof can be replaced with equivalents without departing from the scope of the present invention. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the present invention without departing from the essential scope thereof. Therefore, the present invention is not limited to the specific embodiments disclosed as the best mode contemplated for carrying out the present invention, but the present invention will include all embodiments falling within the scope of the appended claims.

Claims

1. An electrode, the electrode comprising: An active layer, the active layer comprising: A network of high aspect ratio carbon elements, the high aspect ratio carbon elements defining void spaces within the network; A plurality of electrode active material particles, the plurality of electrode active material particles disposed within the void spaces in the network; And A polymer binder, the polymer binder comprising: a first polymer, the first polymer comprising an acid functional group or a salt of such an acid functional group; a polyamide; or an acrylate polymer, and a second polymer.

2. The electrode according to claim 1, wherein the network of high aspect ratio carbon elements comprises: A first group of carbon nanotubes, wherein the first group of carbon nanotubes comprises a plurality of first carbon nanotubes or a plurality of bundles of first carbon nanotubes; and A second group of carbon nanotubes, wherein: The second group of carbon nanotubes comprises a plurality of second carbon nanotubes or a plurality of bundles of second carbon nanotubes; and The second group of carbon nanotubes has one or more properties different from those of the first group of carbon nanotubes.

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

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

5. The electrode according to claim 2, wherein: The first group of carbon nanotubes comprises single-walled carbon nanotubes; The second group of carbon nanotubes comprises multi-walled carbon nanotubes; and The weight ratio of the first group of carbon nanotubes to the second group of carbon nanotubes is about 2:

1.

6. The electrode according to claim 1, wherein the network of high aspect ratio carbon elements comprises a group of multi-walled carbon nanotubes, preferably 0.8 wt% to 2.6 wt%, more preferably between 1 wt% and 1.8 wt%, by weight of the active layer.

7. The electrode according to claim 3, wherein the active layer comprises single-walled carbon nanotubes in an amount between 0.2 wt% and 0.6 wt%, preferably between 0.3 wt% and 0.5 wt%, by weight of the active layer.

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

9. An energy storage device, the energy storage device comprising: An electrolyte; And An electrode according to any one of the preceding claims.

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

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

12. The electrode according to claim 5, wherein the single-walled carbon nanotubes have: An average diameter between 0.5 nm and 5 nm, preferably between 3 nm and 5 nm; An average length of from about 10 nm to 20 microns, preferably between 7 microns and 8 microns.

13. The electrode according to claim 5, wherein the single-walled carbon nanotubes have: An average diameter between 3 nm and 5 nm; and An average length of at least 200 microns.

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

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

16. An energy storage device, the energy storage device comprising: A housing; An electrolyte; A first current collector; An anode active material disposed on the first current collector; Wherein the anode active material comprises a network of high aspect ratio carbon elements that define void spaces within the network; A plurality of anode active material particles disposed in the void spaces within the network; And An anode polymer binder, the polymer binder comprising a first polymer that is a polymer comprising an acid functional group or a salt of such an acid functional group or an acrylate polymer; And A second current collector; A cathode active material disposed on the second current collector; Wherein the cathode active material comprises a network of high aspect ratio carbon elements that define void spaces within the network; A plurality of cathode active material particles disposed in the void spaces within the network; Wherein the cathode active material comprises a combination of nickel, manganese, and cobalt; and A cathode polymer binder, the polymer binder comprising a first polymer that is a polymer comprising an acid functional group or a salt of such an acid functional group; a polyamide; or an acrylate polymer, Wherein at least one of the anode polymer binder and the cathode polymer binder further comprises a second polymer.

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

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

Images