Energy Storage Devices

Abstract

Electrode active layers are disclosed that contain a network of high aspect ratio carbon elements (e.g., carbon nanotubes, carbon nanotube bundles, graphene flakes, etc.), which provide a highly electrically conductive scaffold onto which active material can be entangled or hooked to support the layer. A surface treatment can be applied to the high aspect ratio carbon elements to promote adhesion between the active material and the underlying electrode layer, improving the overall connectivity and mechanical stability of the active layer. The surface treatment forms a very thin (possibly monomolecular) layer on the network, leaving large void spaces without bulk binder material, which can instead be filled with active material. The resulting active layers can be formed with excellent mechanical stability, even at high thicknesses and mass loadings of active material.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of Ser. No. 63 / 224,237, filed July 21, 2021, the disclosure of which is incorporated by reference in its entirety herein. [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 dominated the secondary battery market and continue to drive the industry forward as new uses in products are explored.

[0003] 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, the anode and cathode (collectively "electrodes") are formed by mixing 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 stacked or wound and then housed in a pressurized casing containing the electrolyte material, all together forming the lithium ion battery.

[0004] Conventional (or conventional) electrode binders are used that have sufficient adhesion and chemical properties so that the film coated on the current collector will maintain contact with the current collector even when manipulated to fit within a pressurized battery casing. Because the film contains the electrode active material, if the film cannot maintain sufficient contact with the current collector, significant interference with the electrochemical performance of the battery will occur. Additionally, it has been important to select a binder that is mechanically compatible with the electrode active material so as to withstand the degree of expansion and contraction of the electrode active material during charging and discharging of the battery.

[0005] Therefore, binders such as cellulosic binders or crosslinked polymer binders have been used to provide good mechanical properties. However, such binder materials have detrimental effects. For example, the bulk binder fills a volume in the electrode active layer that could otherwise be used to increase the mass loading of the active material and reduce the electrical conductivity of the electrode. Furthermore, the binder tends to react electrochemically with the electrolyte used in the cell (or battery) (especially in high voltage, high current and / or high temperature applications), thus degrading the performance of the cell. Summary of the Invention

[0006] The present application has realized the construction of electrodes that exhibit excellent mechanical stability without the need for bulk polymer binders. In one aspect, the present disclosure describes an embodiment of an electrode active layer that contains a network of high aspect ratio carbon elements (e.g., carbon nanotubes, carbon nanotube bundles, graphene flakes, etc.), which provides a highly electrically conductive scaffold onto which active material can be entangled or hooked to support the layer. As described in more detail below, a surface treatment (or surface treatments) can be applied to the high aspect ratio carbon elements to promote adhesion of the active material to the underlying electrode layer (e.g., current collector layer) and improve the overall connectivity and mechanical stability of the active layer. The surface treatment forms a very thin (possibly monomolecular) layer on the network, leaving large void spaces without bulk binder material, which can instead be filled with active material. The resulting active layer can be formed with excellent mechanical stability, even at high thicknesses and high mass loadings of active material.

[0007] In another aspect, the disclosure describes a method that includes dispersing high aspect ratio carbon elements and a surface treatment material in a solvent to form an initial slurry, the dispersing step forming a surface treatment on the high aspect ratio carbon; mixing an active material into the initial slurry to form a final slurry; coating the final slurry on a substrate; and drying the final slurry to form an electrode active layer.

[0008] The various embodiments may include the features or elements described herein individually or in any suitable combination. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of an electrode featuring an active material layer. [Diagram 2] FIG. 2 is a diagram illustrating in detail one embodiment of the active material layer. [Diagram 3] FIG. 3 is a diagram illustrating in detail another embodiment of the active material layer. [Figure 4]FIG. 4 is an electron micrograph of an active material of the type described herein. [Diagram 5] FIG. 5 is a schematic diagram of an energy storage cell. [Figure 6] FIG. 6 is a flow chart illustrating a method for fabricating the electrode of FIG. [Figure 7] FIG. 7 shows a schematic diagram of a pouch cell battery. [Figure 8] FIG. 8 shows a summary of performance parameters for pouch cell batteries in EV applications. [Figure 9] FIG. 9 shows a summary of performance parameters for the pouch cell battery. [Figure 10] FIG. 10 shows the results of a comparative performance evaluation of a pouch cell battery featuring a binder-free cathode (left plot) and a pouch cell battery featuring a binder-based cathode (right plot). [Figure 11] FIG. 11 shows the results of a comparative performance evaluation of a pouch cell battery featuring a binder-free cathode (upper trace) and a pouch cell battery featuring a binder-based cathode (lower trace). [Figure 12] FIG. 12 is a schematic diagram of a half-cell lithium battery device. [Figure 13] FIG. 13 is a plot of specific capacity versus potential (referenced to Li / Li+ potential) at various current densities for a binder-free cathode half-cell (solid trace) and a reference binder-based cathode half-cell (dotted trace). [Figure 14] FIG. 14 is a plot of potential (referenced to the Li / Li+ potential) versus volumetric capacity at various current densities for a binder-free cathode half-cell (solid trace) and a reference binder-based cathode half-cell (dotted trace). [Figure 15] FIG. 15 shows a plot of volumetric capacity versus current density for a binder-free cathode half-cell (upper trace) and a reference binder-based cathode half-cell (lower trace). [Figure 16] Figure 16 shows Nyquist plots obtained by electrochemical impedance spectroscopy for several vanadium-free cathode half-cells (circle, square and triangle traces) and a reference vanadium-based cathode half-cell. The vanadium-free cathode half-cells show significantly better performance than the reference cell. [Figure 17] FIG. 17 shows the ("NX") NMC811 cathode electrode coating process and roll of the electrode. [Figure 18] FIG. 18 shows the Si—C anode electrode coating process and rolling of the electrode. [Figure 19A] FIG. 19 shows a summary of the mechanical adhesion tests for both NMC811 and Si—C electrodes. [Figure 19B] (see above) [Figure 20] FIG. 20 shows the structure of a pouch cell for evaluating electrode performance. [Figure 21A] FIG. 21 shows the results of half-cell (cathode vs Li / Li+) C-rate fast charge tests for the (NX) cathode electrodes based on various active materials and the PVDF control NMC811 electrode. [Figure 21B] (see above) [Figure 21C] (see above) [Figure 21D] (see above) [Figure 21E] (see above) [Figure 21F] (see above) [Figure 21G] (see above) [Fig. 21H] (see above) [Figure 22A] FIG. 22 shows full cell (NX NMC811||Si-C system) 3.5C rate CC-CV fast charging test results for cathode electrodes based on various active materials. [Figure 22B] (see above) [Diagram 23]FIG. 23 shows the 1C1C cycle life at 30° C. and 50° C. SOC100 calendar life test results for the disclosed battery electrodes for a full cell (NX NMC811||Si-C system). [Figure 24] FIG. 24 shows the cycling performance for the NX NMC811||Si-C1.5Ah pouch cell. [Figure 25A] FIG. 25A shows the 9Ah NMC811||Si-C battery size. [Figure 25B] FIG. 25B shows the initial charge and discharge capacity for the battery in FIG. 25A. [Figure 26] FIG. 26 shows the 9Ah NMC811||Si-C battery energy density calculation and analysis. [Figure 27] Figure 27 shows the volume expansion and fast charging performance of a 9 Ah NMC811||Si-C battery from SOC0 to SOC100. [Figure 28A] FIG. 28A shows the first cycle voltage profile. [Figure 28B] FIG. 28B shows the full cell discharge energy retention after 100 cycles. [Figure 28C] FIG. 28C shows the specific capacity of the anode active layer (coated mass) after 100 cycles of a full cell constructed from a NX NMC811 cathode and a microsilicon dominant anode. [Figure 28D] FIG. 28D shows the capacity of the full cell described above at different C-rates (CC region only). [Figure 29] FIG. 29 shows the cycling performance of NX89% micro-Si anode vs Li / Li+ half-cell with a new type of ionic liquid (IL) electrolyte additive. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 1, an electrode 10 is shown that contains an active layer 100 disposed on a current collector 101. Some embodiments may contain an optional adhesion layer 102 disposed between the active layer 101 and the current collector 102. In other embodiments, the adhesion layer 102 may be absent.

[0011] Current collector 101 can be an electrically conductive layer such as, for example, a metal foil. Optional adhesion layer 102 (which may be absent in some embodiments) can be a layer of a material that promotes adhesion between current collector 102 and active layer 100. Examples of suitable materials for current collector 101 and optional adhesion layer 102 are described in International Publication WO / 2018 / 102652, published June 7, 2018.

[0012] electrode active layer In some embodiments, the active layer 100 can include a three-dimensional network 200 of high aspect ratio carbon elements 201 that define void spaces within the network 200. A plurality of active material particles 300 are disposed in the void spaces within the network 200. Thus, the active material particles are enmeshed or entangled in the network 200, enhancing cohesion of the active layer 100.

[0013] In some embodiments, a surface treatment (or surface treatment) 202 (not shown, see FIG. 2) is applied to the surfaces of the high aspect ratio carbon elements 201 of the network 200. The surface treatment promotes adhesion between the high aspect ratio carbon elements and the active material particles 300. The surface treatment may also promote adhesion between the high aspect ratio carbon elements and the current collector 100 (also referred to herein as the "conductive layer") and / or optional adhesion layer 102.

[0014] As used herein, the term "high aspect ratio carbon elements" refers to carbonaceous elements that have a size in one or more dimensions ("major dimension") that is significantly greater than the size in the lateral dimensions of the element ("minor dimension").

[0015] For example, in some embodiments, the high aspect ratio carbon elements 201 may include flake or plate-shaped elements having two major dimensions and one minor dimension. For example, in some such embodiments, the ratio of the length of each of the major dimensions to the length of the minor dimension may be at least 5x, 10x, 100x, 500x, 1000x, 5000x, 10000x, or more. Exemplary elements of this type include graphene sheets or flakes.

[0016] For example, in some embodiments, the high aspect ratio carbon elements 201 may include elements in the shape of elongated rods or fibers having one long dimension and two short dimensions. For example, in some such embodiments, the ratio of the length of the long dimension to the length of each of the short dimensions may be at least 5x, 10x, 100x, 500x, 1000x, 5000x, 10000x, or more. Exemplary elements of this type include carbon nanotubes, bundles of carbon nanotubes, carbon nanorods, and carbon fibers.

[0017] In some embodiments, the high aspect ratio carbon elements 201 may include single-walled nanotubes (SWNTs), double-walled nanotubes (DWNTs), or multi-walled nanotubes (MWNTs), carbon nanorods, carbon fibers, or mixtures thereof. In some embodiments, the high aspect ratio carbon elements 201 may be formed from interconnected bundles, clusters, or aggregates of CNTs or other high aspect ratio carbon materials. In some embodiments, the high aspect ratio carbon elements 201 may include graphene in the form of sheets, flakes, curved flakes, and / or formed into high aspect ratio cones, rods, and the like.

[0018] In some embodiments, the electrode active layer 100 can include little or no bulk binder material, leaving more space in the network 200 to be occupied by the active material particles 300. For example, in some embodiments, the active layer 200 can include less than 10% by weight, less than 1% by weight, less than 0.1% by weight, less than 0.01% by weight or less of binder material (e.g., polymeric or cellulosic binder material) disposed in the void spaces.

[0019] For example, in some embodiments, the electrode active layer is free or substantially free of polymeric materials or other materials other than the active material 300 and the network 200 (consisting of the high aspect ratio carbon elements 201 and the surface treatment 202 disposed thereon).

[0020] In some embodiments, network 200 is composed largely or entirely of carbon. For example, in some embodiments, network 200 is at least 90% carbon by weight, at least 95% carbon, at least 96% carbon, at least 97% carbon, at least 98% carbon, at least 99% carbon, at least 99.5% carbon, at least 99.9% carbon, or more.

[0021] In some embodiments, the size (e.g., average size, median size, or minimum size) along one or two major dimensions of the high aspect ratio carbon elements 201 forming the network 200 can be at least 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 7000 μm, 800 μm, 900 μm, 1000 μm, or more. For example, in some embodiments, the size (e.g., average size, median size, or minimum size) of the elements 201 forming the network 200 can be in a range of from 1 μm to 1000 μm or less, or a narrower range, such as from 1 μm to 600 μm.

[0022] In some embodiments, the size of the elements may be relatively uniform, for example, in some embodiments, greater than 50%, 60%, 70%, 80%, 90%, 95%, 99% or more of the elements 201 may have a size along one or two major dimensions that is within 10% of the average size for the elements 201 that form the network 200.

[0023] Applicants have found that active layers 100 of the type described herein can have high mass loadings of active material particles 300 and exhibit exemplary performance (e.g., high conductivity, low resistance, high voltage capability, and high energy and power density) even when the mass fraction of network 200-forming elements 201 in layer 100 is very low. For example, in some embodiments, active layer 100 can be at least about 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5% or more active material particles 300 by weight.

[0024] In some embodiments, network 200 forms an interconnected network of highly electrically conductive pathways (e.g., electron or ion transport) for electrical current through active layer 100. For example, in some embodiments, highly conductive (conductive) bonds occur where elements 201 of the network cross one another or are close enough together that charge carriers (e.g., electrons or ions) can quantum tunnel from one element to the next. The interconnected network of highly electrically conductive pathways formed in network 200 creates long conductive pathways to facilitate electrical current flow in and through active layer 100, even though elements 201 make up a relatively small mass percentage of the active layer (e.g., less than 10 wt%, 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, or less, e.g., in the range of 0.5 wt% to 10 wt%, or less, e.g., 1 wt% to 5.0 wt%).

[0025] For example, in some embodiments, the network 200 may include one or more structures of interconnected elements 201 having an overall length along one or more dimensions that is 2, 3, 4, 5, 10, 20, 50, 100, 500, 1000, 10000 or more times greater than the average length of the components 201 forming the structure. For example, in some embodiments, the network 200 may include one or more structures of interconnected elements 200 having an overall length in the range of 2 to 10000 times (or less) than the average length of the components 201 forming the structure. For example, in some embodiments, the network 200 may include highly conductive pathways having lengths greater than 100 μm, 500 μm, 1000 μm, 10000 μm or more (e.g., in the range of 100 μm to 10000 μm or less).

[0026] As used herein, the term “highly conductive (or electrically conductive) pathway” should be understood as a pathway formed by interconnected elements 201 that has a higher electrical conductivity than the electrical conductivity of the active material particles trapped in the network 200.

[0027] Without being bound by theory, in some embodiments, network 200 may be characterized as an electrically interconnected network of elements 201 that exhibit conductivity above a percolation threshold. The percolation threshold is a mathematical concept related to percolation theory, which is the formation of long-range conductivity in a random system. Below the threshold, so-called "giant" connected components of the order of the system size are absent, and above the threshold, giant components of the order of the system size are present.

[0028] In some embodiments, the percolation threshold can be measured by increasing the mass fraction of element 201 in active layer 100 while holding all other properties of the active layer constant and measuring the conductivity of the layer. In some such cases, the threshold can be identified by the mass fraction at which the conductivity of the layer increases sharply and / or above which the conductivity of the layer increases only slightly with further addition of element 201. Such behavior indicates that the threshold necessary for the formation of an interconnected structure providing conductive pathways with lengths on the order of the size of active layer 100 has been crossed.

[0029] 2 is a detailed view of a high aspect ratio carbon element 201 of network 200 (shown in FIG. 1) that is located near several active material particles 300. In the embodiment shown, the surface treatment (or surface treatment) 202 on element 201 is a surfactant layer associated with an outer layer of the surface of element 201. As shown, the surfactant layer includes a plurality of surfactant elements 210, each having a hydrophobic end 211 and a hydrophilic end 212, with the hydrophobic end disposed proximal to the surface of carbon element 201 and the hydrophilic end 212 disposed distal to the surface.

[0030] In some embodiments, the carbon elements 201 are hydrophobic (e.g., typical of nano-form carbon elements such as CNTs, CNT bundles, and graphene flakes), and the hydrophobic ends 211 of the surfactant elements 210 are attracted to the carbon elements 201. Thus, in some embodiments, the surface treatment 202 can be a self-assembled layer. For example, as described in more detail below, in some embodiments, when the elements 201 are mixed with the surfactant elements 210 in a solvent to form a slurry, the surface treatment 202 layer self-assembles on the surface due to electrostatic interactions between the elements 201 and 210 in the slurry.

[0031] In some embodiments, the surface treatment 202 can be a self-limiting layer. For example, as described in more detail below, in some embodiments, when element 201 is mixed with surfactant element 210 in a solvent to form a slurry, the surface treatment 202 layer self-assembles on the surface due to electrostatic interactions between elements 201 and 210 in the slurry. In some embodiments, once an area of ​​the surface of element 201 is covered with surfactant element 210, additional surfactant elements 210 are not attracted to that area. In some embodiments, once the surface of element 201 is covered with surfactant element 202, additional elements are repelled from the layer, making it a self-limiting process. For example, in some embodiments, the surface treatment 202 forms in a self-limiting process, which ensures that the layer is thin, e.g., a single molecule or a few molecules thick.

[0032] In some embodiments, at least some of the hydrophilic ends 212 of the surfactant elements form bonds with the active material particles 300. Thus, the surface treatment 202 can provide good adhesion between the elements 201 of the network 200 and the active material particles. In some embodiments, the bonds can be covalent bonds, or non-covalent bonds, such as π-π bonds, hydrogen bonds, electrostatic bonds, or combinations thereof.

[0033] For example, in some embodiments, the hydrophilic ends 212 of the surfactant elements 210 have a polarized charge of a first polarity, while the surfaces of the active material particles 300 carry a polarized charge of a second polarity opposite the first polarity, and thus are attracted to each other.

[0034] For example, in some embodiments, during formation of layer 100, active material particles 300 are combined in a solvent with carbon elements 201 having surface treatment 202 (described in more detail below), and the outer surfaces of active material particles 300 may be characterized by a zeta potential (as known in the art) of opposite sign to the zeta potential of the outer surface of surface treatment 202. Thus, in some embodiments, the attraction between carbon elements 201 having surface treatment 202 and active material particles 300 promotes self-assembly of a structure in which active material particles 300 are hooked to carbon elements 201 of network 200.

[0035] In some embodiments, at least some of the hydrophilic ends 212 of the surfactant elements form bonds with an adhesion or current collector layer underlying the active material layer 100. Thus, the surface treatment 202 can provide good adhesion between the elements 201 of the network 200 and such underlying layers. In some embodiments, the bonds can be covalent or non-covalent, such as π-π bonds, hydrogen bonds, electrostatic bonds, or combinations thereof. In some embodiments, this configuration provides good mechanical stability of the electrode 10, as described in more detail below.

[0036] In various embodiments, the surfactant used to form the surface treatment 202 as described above may include any suitable material. For example, in some embodiments, the surfactant may include one or more of the following: hexadecyltrimethylammonium hexafluorophosphate (CTAP), hexadecyltrimethylammonium tetrafluoroborate (CTAB), hexadecyltrimethylammonium acetate, hexadecyltrimethylammonium nitrate, hocamidopropyl betaine, N-(cocoalkyl)-N,N,N-trimethylammonium methyl sulfate, and cocoamidopropyl betaine. Additional suitable materials are described below.

[0037] In some embodiments, the surfactant layer 202 may be formed by dissolving a compound in a solvent such that the surfactant layer is formed from ions derived from the compound (e.g., the self-limiting process described above). In some embodiments, the active layer 100 will thus include residual (or remaining) counter ions 214 to the surfactant ions that form the surface treatment 202.

[0038] In some embodiments, the surfactant counterion 214 is selected to be compatible with use in an electrochemical cell. For example, in some embodiments, the counterion is selected to be non-reactive or only mildly reactive with the materials used in the cell, such as the electrolyte, separator, housing, etc. For example, if an aluminum housing is used, the counterion may be selected to be non-reactive or only mildly reactive with the aluminum housing.

[0039] For example, in some embodiments, the residual counter ions are free or substantially free of halide groups. For example, in some embodiments, the residual counter ions are free or substantially free of bromine.

[0040] In some embodiments, the residual counter ions can be selected to be compatible with the electrolyte used in the energy storage cell containing the active layer 200. For example, in some embodiments, the residual counter ions can be the same species as the ions used in the electrolyte. For example, if the electrolyte contains a dissolved LiPF6 salt, the electrolyte anion is PF6. In such a case, the surfactant can be selected as, for example, CTAPF6, and the surface treatment 202 is formed as a layer of anions derived from CTAPF6, while the residual surfactant counter ions are PF6 anions derived from CTAPF6 (and thus match the anions of the electrolyte).

[0041] In some embodiments, the surfactant material used can be soluble in a solvent that exhibits advantageous properties.For example, in some embodiments, the solvent can include water, or alcohol, such as methanol, ethanol, or 2-propanol (isopropyl alcohol, often referred to as IPA), or a mixture thereof.In some embodiments, the solvent can include one or more additives that are used to further improve the properties of the solvent, such as low-boiling additives, such as acetonitrile (ACN), deionized water, and tetrahydrofuran.

[0042] For example, if a low boiling point solvent is used to form the surface treatment 202, the solvent may be quickly removed using a thermal drying process (e.g., of the type described in more detail below) carried out at a relatively low temperature. As will be appreciated by those skilled in the art, this may improve the speed and / or cost of manufacturing the active layer 202.

[0043] For example, in some embodiments, the surface treatment 202 is formed from a material that is soluble in a solvent having a boiling point below 250°C, 225°C, 202°C, 200°C, 185°C, 180°C, 175°C, 150°C, 125°C, or lower, e.g., below 100°C.

[0044] In some embodiments, the solvent may exhibit other advantageous properties. In some embodiments, the solvent may have a low viscosity, e.g., a viscosity of 3.0 centipoise, 2.5 centipoise, 2.0 centipoise, 1.5 centipoise or less at 20° C. In some embodiments, the solvent may have a low surface tension, e.g., a surface tension of 40 mN / m, 35 mN / m, 30 mN / m, 25 mN / m or less at 20° C. In some embodiments, the solvent may have low toxicity, e.g., toxicity comparable to that of alcohol, such as isopropyl alcohol.

[0045] Notably, this contrasts with processes for forming conventional electrode active layers that feature bulk binder materials such as polyvinylidene fluoride or polyvinylidene difluoride (PVDF). Such bulk binders often require aggressive solvents characterized by high boiling points. One such example is n-methyl-2-pyrrolidone (NMP). The use of NMP (or other pyrrolidone-based solvents) as a solvent requires high temperature drying processes to remove the solvent. Furthermore, NMP is expensive, requires complex solvent recovery systems, is highly toxic, and poses significant safety issues. In contrast, as described in more detail below, in various embodiments, the active layer 200 can be formed without the use of NMP or similar compounds such as pyrrolidone compounds.

[0046] While one exemplary class of surface treatment 202 is described above, it is understood that other treatments may be used. For example, in various embodiments, surface treatment 202 may be formed by functionalizing high aspect ratio carbon elements 201 using any suitable technique described herein or known in the art. The functional groups applied to elements 201 are selected to promote adhesion between active material particles 300 and network 200. For example, in various embodiments, the functional groups may include carboxyl groups, hydroxyl groups, amino groups, silano groups, and combinations thereof.

[0047] As described in more detail below, in some embodiments, the functionalized carbon elements 201 are formed from a dried (e.g., freeze-dried) aqueous dispersion that includes nanoform carbon and a functionalizing material, such as, for example, a surfactant. In some such embodiments, the aqueous dispersion is substantially free of materials that would damage the carbon elements 201, such as acids.

[0048] 3, in some embodiments, the surface treatment 202 on the high aspect ratio carbon element 201 comprises a thin polymer layer disposed on the carbon element that promotes attachment of the active material to the network. In some embodiments, the thin polymer layer comprises a self-assembled or self-limiting polymer layer. In some embodiments, the thin polymer layer bonds to the active material, for example, via hydrogen bonding.

[0049] In some embodiments, the thin polymer layer may have a thickness that is less than 3 times, 2 times, 1 time, 0.5 times, 0.1 times (or less) the minor dimension of the element 201 in a direction perpendicular to the outer surface of the carbon element.

[0050] In some embodiments, the thin polymer layer includes functional groups (e.g., side chain functional groups) that bond to the active material via non-covalent bonds, such as π-π bonds, hi some embodiments, the thin polymer layer can form a stable coating layer over at least a portion of element 201.

[0051] In some embodiments, the thin polymer layer covering some of the elements 201 may be bonded to the adhesion layer 102 or current collector 101 underlying the active layer 200. For example, in some embodiments, the thin polymer layer includes side chain functional groups that bond to the surface of the adhesion layer 102 or current collector 101 via non-covalent bonds, such as π-π bonds. In some such embodiments, the thin polymer layer may form a stable coating layer that covers at least a portion of the elements 201. In some embodiments, this configuration provides excellent mechanical stability of the electrode 10, as described in more detail below.

[0052] In some embodiments, the polymeric material is miscible in a solvent of the type described in the examples above. For example, in some embodiments, the polymeric material is miscible in a solvent that includes an alcohol, such as methanol, ethanol, 2-propanol (isopropyl alcohol, often referred to as IPA), or a combination thereof. In some embodiments, the solvent may include one or more additives that are used to further improve the properties of the solvent, such as low-boiling additives, such as acetonitrile (ACN), deionized water, and tetrahydrofuran.

[0053] Suitable examples of materials that may be used to form the polymer layer include water-soluble polymers, such as polyvinylpyrrolidone, etc. Additional exemplary materials are described below.

[0054] In some embodiments, the polymeric material has a low molecular mass, for example, up to 1,000,000 g / mol, 500,000 g / mol, 100,000 g / mol, 50,000 g / mol, 10,000 g / mol, 5,000 g / mol, 2,500 g / mol or less.

[0055] It should be noted that the polymer layers described above are qualitatively distinct from the bulk polymer binders used in conventional electrodes: rather than filling a significant portion of the volume of the active layer 100, the thin polymer layers reside on the surfaces of the high aspect ratio carbon elements, leaving most of the void space within the network 200 capable of holding the active material particles 300.

[0056] For example, in some embodiments, the thin polymer layer has a maximum thickness that is 1x, 0.5x, 0.25x or less than the size of the carbon element 201 along its minor dimension in a direction perpendicular to the outer surface of the network. For example, in some embodiments, the thin polymer layer can be a few molecules thick (e.g., 100, 50, 10, 5, 4, 3, 2, or 1 molecule thick or less). Thus, in some embodiments, less than 10%, 5%, 1%, 0.1%, 0.01%, 0.001% or less of the volume of the active layer 100 is filled with the thin polymer layer.

[0057] In still further exemplary embodiments, the surface treatment 202 may be formed from a layer of carbonaceous material derived from pyrolysis of a polymeric material disposed on the high aspect ratio carbon elements 201. Such a layer of carbonaceous material (e.g., graphitic or amorphous carbon) may adhere or facilitate attachment (e.g., via covalent bonds) to the active material particles 300. Examples of suitable pyrolysis techniques are described in U.S. Patent Application No. 63 / 028982, filed May 20, 2020. One polymeric material suitable for use with this technique is polyacrylonitrile (PAN).

[0058] In various embodiments, the active material particles 300 include any active material suitable for use in an energy storage device, including metal oxides such as lithium metal oxides. For example, the active material particles 300 may include any active material suitable for use in an energy storage device, including metal oxides such as lithium metal oxides. For example, the active material particles 300 may include any active material suitable for use in an energy storage device, including lithium cobalt oxide (LCO, a chemical compound often referred to as "lithium cobaltate" or "lithium cobaltite," with one possible variant having the formula LiCoO2; lithium nickel manganese cobalt oxide (NMC, with variants having the formula LiNiMnCo); lithium manganese oxide (LMO, with variants having the formula LiMn2O4, Li2MnO3, and others); lithium nickel cobalt aluminum oxide (LiNiCoAlO2, and variants thereof as NCA), and lithium titanate oxide (LTO, with one variant having the formula Li4Ti5O3). 12); lithium iron phosphate oxide (LFP, one variant has the formula LiFePO4), lithium nickel cobalt aluminum oxide (and its variants as NCA), and other similar materials. Other variants of the above may also be included.

[0059] In some embodiments, when NMC is used as an active material, nickel-rich NMC may be used. For example, in some embodiments, a variant of NMC is LiNi x Mn y Co 1-x-y (wherein x can be about 0.7, 0.75, 0.80, 0.85 or more). In some embodiments, so-called NMC811 (wherein x is about 0.8 and y is about 0.1) can be used.

[0060] In some embodiments, the active material is another form of lithium nickel manganese cobalt oxide (LiNi x Mn y Co z O2). For example, common variants such as NMC111 (LiNi 0.33 Mn 0.33 Co 0.33 O2);NMC532(LiNi 0.5 Mn 0.3 Co 0.2 O2;NMC622(LiNi 0.6 Mn 0.2 Co 0.2 O2) and others may be used, including but not limited to:

[0061] In some embodiments, for example when the electrode is used as an anode, the active material may include graphite, hard carbon, activated carbon, nano-formed carbon, silicon, silicon oxide, silicon nanoparticles embedded in carbon, etc. In some embodiments, the active layer 100 may be intercalated with lithium, for example using pre-lithiation methods known in the art.

[0062] In some embodiments, the techniques described herein allow active layer 100 to be constructed with a majority of the material in the active layer, e.g., greater than 75%, 80%, 85%, 90%, 95%, 99%, 99.5%, 99.9% or more by weight, while exhibiting excellent mechanical properties (e.g., no delamination during operation in an energy storage device of the type described herein). For example, in some embodiments, the active layer may have a high amount of active material as described above and a high thickness (e.g., greater than 50 μm, 100 μm, 150 μm, 200 μm, or more) while exhibiting excellent mechanical properties (e.g., no delamination during operation in an energy storage device of the type described herein).

[0063] The active material particles 201 in the active layer 100 may be characterized by a median particle size that is, for example, in the range of 0.1 μm to 50 μm or less. The active material particles 201 in the active layer 100 may be characterized by a particle size distribution that is monomial, bimodal, or multimodal particle size distribution. 2 / g or more 100m 2 / g and narrower ranges.

[0064] In some embodiments, the active layer 100 has a thickness of at least 20 mg / cm, for example. 2 , 30mg / cm 2 , 40mg / cm 2 , 50mg / cm 2 , 60 mg / cm 2 , 70mg / cm 2 , 80mg / cm 2 , 90mg / cm 2 , 100mg / cm 2 , or even more.

[0065] Referring to Figure 4, an electron microscope photograph of an exemplary active material layer of the type described herein is shown. Tendril-like, high aspect ratio carbon elements 201 (formed from CNT bundles) are clearly shown enmeshing active material particles 300. Note the absence of bulk polymeric material occupying space within the layer.

[0066] Energy Storage Cells 5, an energy storage cell (or battery) 500 is shown that includes a first electrode 501 and a second electrode 502, a permeable separator 503 disposed between the first electrode 501 and the second electrode 502, and an electrolyte 504 that wets the first electrode 501 and the second electrode 502. Either or both of the electrodes 501, 502 may be of a type described herein.

[0067] In some embodiments, the energy storage cell 500 can be a battery, such as a lithium ion battery. In some embodiments, the electrolyte can be a lithium salt dissolved in a solvent, such as the type described in Qi Li, Juner Chen, Lei Fan, Xueqian Kong, Yingyping Lu, “Progress in electrolytes for rechargeable Li-based batteries and beyond”, Green Energy & Environment, Volume 1, Issue 1, Pages 18-42, the entire contents of which are incorporated herein by reference.

[0068] In some embodiments, the energy storage cell may have an operating voltage in the range of 1.0V or more and 5.0V or less, or in a narrower range, for example, 2.3V or more and 4.3V or less.

[0069] In some embodiments, the energy storage cell 500 may have an operating temperature in the range of -40°C or more and 100°C or less, or in a narrower range, such as -10°C or more and 60°C or less.

[0070] In some embodiments, the energy storage cell 500 may have a gravimetric energy density of at least 100 Wh / kg, 200 Wh / kg, 300 Wh / kg, 400 Wh / kg, 500 Wh / kg, 1000 Wh / kg, or more.

[0071] In some embodiments, the energy storage cell 500 may have a volumetric energy density of at least 200 Wh / L, 400 Wh / L, 600 Wh / L, 800 Wh / L, 1000 Wh / L, 1500 Wh / L, 2000 Wh / L, or more.

[0072] In some embodiments, the energy storage cell 500 may have a C-rate in the range of 0.1 to 50, inclusive.

[0073] In some embodiments, the energy storage cell 500 may have a cycle life of at least 1000, 1500, 2000, 2500, 3000, 3500, 4000, or more charge / discharge cycles.

[0074] In some embodiments, the energy storage cell 500 may be a lithium ion capacitor of the type described in U.S. Patent Application No. 63 / 021492, filed May 8, 2020.

[0075] In some such embodiments, the energy storage cell 500 may have an operating temperature range including from -60°C to 100°C or a narrower range such as from -45°C to 85°C.

[0076] In some such embodiments, the energy storage cell 500 may have a gravimetric energy density of at least 10 Wh / kg, 15 Wh / kg, 20 Wh / kg, 30 Wh / kg, 40 Wh / kg, 50 Wh / kg, or more.

[0077] In some such embodiments, the energy storage cell 500 may have a volumetric energy density of at least 20 Wh / L, 30 Wh / L, 40 Wh / L, 50 Wh / L, 60 Wh / L, 70 Wh / L, 80 Wh / L, or more.

[0078] In some such embodiments, the energy storage cell 500 may have a gravimetric power density of at least 5 kW / kg, 7.5 kW / kg, 10 kW / kg, 12.5 kW / kg, 14 kW / kg, 15 kW / kg, or more.

[0079] In some such embodiments, the energy storage cell 500 may have a volumetric power density of at least 10 kW / L, 15 kW / L, 20 kW / L, 22.5 kW / L, 25 kW / L, 28 kW / L, 30 kW / L, or more.

[0080] In some such embodiments, the energy storage cell 500 may have a C-rate in the range of 1.0 to 100, inclusive.

[0081] In some such embodiments, the energy storage cell 500 may have a cycle life of at least 100,000, 500,000, 1,000,000, or more charge / discharge cycles.

[0082] How to assemble An electrode 10 featuring an active layer 100 as described herein may be fabricated using any suitable manufacturing method. As will be appreciated by those of skill in the art, in some embodiments, the electrode 10 may be fabricated using wet coating techniques of the type described in International Publication WO2018 / 102652, published June 7, 2018, in light of the further teachings described herein.

[0083] 6, in some embodiments, the active layer 100 of the electrode 10 may be formed using a method 1000. At step 1001, high aspect ratio carbon elements 201 and a surface treatment material (e.g., a polymeric material or a surfactant as described herein) are combined with a solvent (of the type described herein) to form an initial slurry.

[0084] At step 1002, the initial slurry is processed to ensure good dispersion of the solid materials in the slurry. In some embodiments, this processing can include introducing mechanical energy into the mixture of solvent and solid materials (e.g., using an ultrasonic disintegrator, which may often be referred to as 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 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 in a narrower range, such as 0.4 kWh / kg to 0.6 kWh / kg.

[0085] In some embodiments, an ultrasonic bath mixer may be used. In other embodiments, a probe sonicator (or probe ultrasonic disintegrator) may be used. Probe sonication can be significantly more powerful and effective for nanoparticle applications compared to ultrasonic baths. The high shear forces generated by ultrasonic cavitation have the ability to break down particle agglomerates, resulting in smaller and more uniform particle sizes. Among other things, sonication can obtain a stable and homogenous suspension of solids in a slurry. Generally, this results in dispersion as well as deagglomeration and other breakup of solids. Examples of probe sonication devices include the Q-series probe sonicators available from QSonia LLC (Newtown, CT). Other examples include the Branson Digital SFX-450, commercially available from Thomas Scientific (Swedesboro, NJ).

[0086] However, in some embodiments, the local nature of each probe within the probe device may result in non-uniform mixing and suspension, as may occur, for example, with large samples. This may occur when using a continuous flow cell and proper mixing setup, i.e., in such a setup, mixing of the slurry will result in a satisfactory, but not perfect, homogenous dispersion.

[0087] In some embodiments, the initial slurry, once processed, will have a viscosity in the range of from 5,000 cps to 25,000 cps, or narrower, such as from 6,000 cps to 19,000 cps.

[0088] In step 1003, a surface treatment 202 may be fully or partially formed on the high aspect ratio carbon elements 201 in the initial slurry. In some embodiments, at this stage, the surface treatment 202 may be self-assembled, as described in detail above with reference to Figures 2 and 3. The resulting surface treatment 201 may include functional groups or other features (which will be described in further steps below) that may promote adhesion between the high aspect ratio carbon elements 201 and the active material particles 300.

[0089] In step 1004, active material particles 300 may be combined with the initial slurry to form a final slurry containing active material particles 300 with high aspect ratio carbon elements 201 having surface treatments 202 formed thereon.

[0090] In some embodiments, active material 300 may be added directly to the initial slurry. In other embodiments, active material 300 may first be dispersed in a solvent (e.g., using the techniques described above in connection with the initial solvent) to form an active material slurry, which may then be combined with the initial slurry to form the final slurry.

[0091] In step 1005, 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 in connection with step 1002. In some embodiments, a planetary mixer may be used, such as a multi-shaft (e.g., three or more shaft) planetary mixer. In some embodiments, the planetary mixer may feature multiple blades, such as two or more mixing blades and one or more (e.g., two, three or more) dispersion blades, such as a disk dispersion blade.

[0092] In some embodiments, during step 1005, the matrix 200 trapping (or entrapping) the active material 300 may fully or partially self-assemble, as described in detail above with reference to Figures 2 and 3. In some embodiments, an interaction between the surface treatment 202 and the active material 300 facilitates the self-assembly process.

[0093] In some embodiments, the final slurry, upon processing, will have a viscosity in the range of from 1000 cps to 10,000 cps, or narrower, such as from 2500 cps to 6000 cps.

[0094] In step 1006, the active layer 100 is formed from the final slurry. In some embodiments, the final slurry may be cast wet directly onto the current collector conductive layer 101 (or optional adhesive layer 102) and dried. By way of example, casting may be by applying heat and / or vacuum until substantially all of the solvent and any other liquids are removed, thereby forming the active layer 100. In some such embodiments, it may be desirable to protect various portions of the underlying layers. For example, if the electrode 10 is intended for use in double-sided operation, it may be desirable to protect the underside of the conductive layer 101. Protection may include protection from the solvent, for example, by masking predetermined areas or by providing a drain for removal of the solvent.

[0095] In other embodiments, the final slurry may be at least partially dried elsewhere using any suitable technique (e.g., roll-to-roll layer application) and transferred onto the adhesive layer 102 or conductive layer 101 to form the active layer 100. In some embodiments, the combined wet slurries may be placed onto an intermediate material having a suitable surface and dried to form a layer (i.e., the active layer). Any material having a suitable surface may be used as the intermediate material, illustratively including PTFE, which by its nature is easy to subsequently remove from the surface. In some embodiments, the selected layer is formed in a press to provide a layer exhibiting a desired thickness, area, and density.

[0096] In some embodiments, the final slurry is formed into a sheet and coated onto the adhesive layer 102 or the conductive layer 101 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 leveled (e.g., using a doctor blade) to the desired thickness after it is applied. A variety of other techniques may be used to apply the slurry. For example, coating techniques 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 using a smaller diameter gravure roll; bar coating; three reverse roll coating (top feed); three reverse roll coating (fountain die); reverse roll coating, and others.

[0097] The viscosity of the final slurry may vary depending on the application technique. For example, in comma coating, the viscosity may range from about 1000 cps to about 200000 cps. Lip die coating provides coating with a slurry exhibiting a viscosity in the range of about 500 cps to about 300000 cps. Reverse kiss coating provides coating with a slurry exhibiting a viscosity in the range of about 5 cps to about 1000 cps. In some embodiments, each layer may be formed by multiple passes.

[0098] In some embodiments, the active layer 100 formed from the final slurry may be compressed (e.g., using a calendaring apparatus) before or after it is applied to the electrode 10. In some embodiments, the slurry may be partially or completely dried (e.g., by application of 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 that is less than 90%, 80%, 70%, 50%, 40%, 30%, 20%, 10%, or less (e.g., in a direction perpendicular to the current collector layer 101) of its pre-compression thickness.

[0099] 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 application of heat, vacuum, or a combination thereof). In some embodiments, substantially all of the solvent is removed from active layer 100.

[0100] In some embodiments, the solvent used to form the slurry is recovered and recycled into the slurry making process.

[0101] In some embodiments, the active layers may be compressed, for example to break down some of the constituent high aspect ratio carbon elements or other carbonaceous materials, and to increase the surface area of ​​each layer. In some embodiments, this compression process may increase one or more of the adhesion between the layers, the ionic transport rate within the layers, and the surface area of ​​the layers. In various embodiments, compression may be applied before or after each layer is applied or formed into electrode 10.

[0102] In some embodiments, when calendaring is used to compress the active layer 100, the calendaring equipment can be set with a gap spacing of 90%, 80%, 70%, 50%, 40%, 30%, 20%. 10% or less of the pre-compression thickness of the layer (e.g., set to about 33% of the pre-compression thickness of the layer). The calendar rolls can be configured to provide a suitable pressure, such as 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 can have a density in the range of 1 g / cc to 10 g / cc or less, or a narrower range, such as 2.5 g / cc to 4.0 g / cc or less. In some embodiments, the calendaring process can be carried out at a temperature in the range of 20°C to 140°C or less, or a narrower range. In some embodiments, the active layer can be preheated prior to calendering, for example at a temperature in the range of 20° C. to 100° C., or less.

[0103] Once the electrode 10 is assembled, the electrode 100 may be used to assemble an energy storage device 10. Assembly of the energy storage device 10 may follow conventional steps used for assembling an electrode with a separator and placing into a housing, such as a canister or pouch, and may further include additional steps for electrolyte addition and sealing of the housing.

[0104] In various aspects, the method 1000 may include the following features (individually or in any suitable combination).

[0105] In some embodiments, the initial slurry has a solids content in the range of from 0.1 to 20.0 wt % (or a narrower range), and in some embodiments, the final slurry has a solids content in the range of from 10.0 to 80 wt % (or a narrower range).

[0106] In various embodiments, the solvent used can be any of those described herein in connection with forming the surface treatment 202. In some embodiments, the surfactant material used to form the surface treatment 202 can be soluble in a solvent that exhibits advantageous properties. For example, in some embodiments, the solvent can include water, or an alcohol, such as methanol, ethanol, or 2-propanol (isopropyl alcohol, often referred to as IPA), or a mixture thereof. In some embodiments, the solvent can include one or more additives used to further enhance the properties of the solvent, such as low boiling additives, such as acetonitrile (ACN), deionized water, and tetrahydrofuran.

[0107] In some embodiments, when a low boiling point solvent is used, the solvent can be quickly removed using a thermal drying process carried out at a relatively low temperature. As will be appreciated by those skilled in the art, this can increase the speed and / or cost of manufacturing the electrode 10. For example, in some embodiments, the solvent can have a boiling point below 250° C., 225° C., 202° C., 200° C., 185° C., 180° C., 175° C., 150° C., 125° C., or lower, such as 100° C. or lower.

[0108] In some embodiments, the solvent may exhibit other advantageous properties. In some embodiments, the solvent may have a low viscosity, e.g., a viscosity of 3.0 centipoise, 2.5 centipoise, 2.0 centipoise, 1.5 centipoise or less at 20° C. In some embodiments, the solvent may have a low surface tension, e.g., a surface tension of 40 mN / m, 35 mN / m, 30 mN / m, 25 mN / m or less at 20° C. In some embodiments, the solvent may have low toxicity, e.g., toxicity comparable to that of alcohol, such as isopropyl alcohol.

[0109] In some embodiments, during the formation of the active layer, the material forming the surface treatment may be dissolved in a solvent that is substantially free of pyrrolidone compounds. In some embodiments, the solvent is substantially free of n-methyl-2-pyrrolidone.

[0110] In some embodiments, the surface treatment 201 is formed from a material that includes a surfactant of the type described herein.

[0111] In some embodiments, dispersing the high aspect ratio carbon elements and the surface treatment material in a solvent to form an initial slurry includes applying a force to the aggregated carbon elements to slide the elements away from each other along a direction transverse to the minor axis of the elements. In some embodiments, techniques for forming such a dispersion may be adapted from those described in International Publication WO2018 / 102652, published June 7, 2018, in light of the teachings described herein.

[0112] In some embodiments, the high aspect ratio carbon elements 201 may be functionalized prior to forming a slurry used to form the electrode 10. For example, in one aspect, a method is disclosed that includes dispersing the high aspect ratio carbon elements 201 and a surface treatment material in an aqueous solvent to form an initial slurry, the dispersing step forming a surface treatment on the high aspect ratio carbon; drying the initial slurry to remove substantially all of the water, resulting in a dry powder of the high aspect ratio carbon and the surface treatment thereon. In some embodiments, the dry powder may be combined with, for example, a slurry of solvent and active material to form a final slurry of the type described above in connection with method 1000.

[0113] In some embodiments, drying the initial slurry comprises lyophilizing (freeze-drying) the initial slurry. In some embodiments, the aqueous solvent and the initial slurry are substantially free of materials that damage the high aspect ratio carbon elements. In some embodiments, the aqueous solvent and the initial slurry are substantially free of acids. In some embodiments, the initial slurry consists essentially of the high aspect ratio carbon elements, the surface treatment material, and water.

[0114] Some embodiments further include dispersing the dry powder of high aspect ratio carbon with a surface treatment in a solvent and adding an active material to form a second slurry; coating the second slurry onto a substrate; and drying the second slurry to form an electrode active layer. In some embodiments, the preceding steps may be performed using techniques adapted from those described in International Publication WO2018 / 102652, published June 7, 2018, in light of the teachings described herein.

[0115] In some embodiments, the final slurry may include a polymer additive, such as, for example, polyacrylic acid (PAA), poly(vinyl alcohol) (PVA), poly(vinyl acetate) (PVAc), polyacrylonitrile (PAN), polyisoprene (PIpr), polyaniline (PANi), polyethylene (PE), polyimide (PI), polystyrene (PS), polyurethane (PU), polyvinyl butyral (PVB), polyvinylpyrrolidone (PVP), and the like. In some embodiments, the active layer may be treated by applying heat to pyrolyze the additive, such that the surface treatment 202 forms a layer of carbonaceous material obtained by pyrolysis of the polymer additive. Such a layer of carbonaceous material (e.g., graphitic or amorphous carbon) may adhere or promote adhesion (e.g., via covalent bonds) to the active material particles 300. The heat treatment may be applied by any suitable means, such as by applying a laser beam. Examples of suitable pyrolysis techniques are described in U.S. Patent Application No. 63 / 028982, filed May 22, 2020.

[0116] Surfactants The techniques described above involve the use of surfactants for surface treatment on the high aspect ratio carbon nanotubes 201 to promote adhesion with the active material particles 300. Although several advantageous and suitable surfactants have been described above, it will be appreciated that other surfactant materials may be used, including the following:

[0117] Surfactants are molecules or groups of molecules that have surface activity, including wetting agents, dispersants, emulsifiers, detergents, and foaming agents. A variety of surfactants can be used to prepare the surface treatments described herein. Typically, the surfactants used include a lipophilic non-polar hydrocarbon group and a polar functional hydrophilic group. The polar functional group can be a carboxylate, ester, amine, amide, imide, hydroxyl, ether, nitrile, phosphate, sulfate, or sulfone. Surfactants can be used alone or in combination. Thus, surfactant combinations can include anionic, cationic, nonionic, zwitterionic, amphoteric, and ampholytic surfactants, so long as there is a net positive or negative charge at the head region of the population of surfactant molecules. In some aspects, a single negatively or positively charged surfactant is used to prepare the electrode composition of the present disclosure.

[0118] The surfactants used in the preparation of the electrode composition of the present disclosure may be anionic, including, but not limited to, sulfonates, such as alkyl sulfonates, alkyl benzene sulfonates, alpha olefin sulfonates, paraffin sulfonates, and alkyl ester sulfonates; sulfates, such as alkyl sulfates, alkyl alkoxy sulfates, and alkyl alkoxylated sulfates; phosphates, such as monoalkyl phosphates and dialkyl phosphates; phosphonates; carboxylates, such as fatty acids, alkyl alkoxy carboxylates, sarcosinates, isethionates, and taurates. Specific examples of carboxylates include sodium oleate, sodium cocoyl isethionate, sodium methyl oleoyl taurate, sodium laureth carboxylate, sodium trideceth carboxylate, sodium lauryl sarcosinate, lauroyl sarcosinic acid, and cocoyl sarcosinate. Specific examples of sulfates include sodium dodecyl sulfate (SDS), sodium lauryl sulfate, sodium laureth sulfate, sodium trideceth sulfate, sodium tridecyl sulfate, sodium cocyl sulfate, and sodium lauryl monoglyceride sulfate.

[0119] Suitable sulfonate surfactants include, but are not limited to, alkyl sulfonates, aryl sulfonates, monoalkyl and dialkyl sulfosuccinates, and monoalkyl and dialkyl sulfosuccinamates. Each alkyl group independently contains about 2 to 20 carbons and may be ethoxylated with an average of up to about 8 units, preferably up to about 6 units, e.g., 2, 3, or 4 units of ethylene oxide per alkyl group. Representative examples of alkyl and aryl sulfonates are sodium tridecylbenzene sulfonate (STBS) and sodium dodecylbenzene sulfonate (SDBS).

[0120] Representative examples of sulfosuccinates are dimethicone copolyol sulfosuccinate, diamyl sulfosuccinate, dicapryl sulfosuccinate, dicyclohexyl sulfosuccinate, diheptyl sulfosuccinate, dihexyl sulfosuccinate, diisobutyl sulfosuccinate, dioctyl sulfosuccinate, C12-15 pareth sulfosuccinate, cetearyl sulfosuccinate, cocopolyglucose sulfosuccinate, butyl cocoyl gluceth-10 sulfosuccinate, deceth-5 sulfosuccinate, deceth-6 sulfosuccinate, dihydroxyethyl sulfosuccinate undecylenate, hydrogenated cottonseed glycerides sulfosuccinate, sulfosuccinic acid salt ... These include, but are not limited to, isodecyl sulfosuccinate, isostearyl sulfosuccinate, laneth-5 sulfosuccinate, laureth sulfosuccinate, laureth-12 sulfosuccinate, laureth-6 sulfosuccinate, laureth-9 sulfosuccinate, lauryl sulfosuccinate, nonoxynol-10 sulfosuccinate, oleth-3 sulfosuccinate, oleyl sulfosuccinate, PEG-10 lauryl citrate sulfosuccinate, sitosereth-14 sulfosuccinate, stearyl sulfosuccinate, tallow, tridecyl sulfosuccinate, ditridecyl sulfosuccinate, bisglycol ricinosulfosuccinate, di(1,3-di-methylbutyl) sulfosuccinate, and silicone copolyol sulfosuccinate.

[0121] Representative examples of sulfosuccinamates are sulfosuccinic acid lauramide MEA, sulfosuccinic acid oleamide PEG-2, sulfosuccinic acid cocamide MIPA, sulfosuccinic acid cocamide PEG-3, sulfosuccinic acid isostearamide MEA, sulfosuccinic acid isostearamide IPA, sulfosuccinic acid lauramide MEA, sulfosuccinic acid lauramide PEG-2, sulfosuccinic acid lauramide PEG-5, sulfosuccinic acid myristamide MEA, sulfosuccinic acid oleamide MEA, sulfosuccinic acid oleamide PIPA, sulfosuccinic acid oleamide PEG-2, sulfosuccinic acid palmitamide PEG-2, Examples of sulfosuccinic acid include, but are not limited to, palmitolamide PEG-2 sulfosuccinic acid, PEG-4 cocamide MIPA sulfosuccinic acid, ricinoleamide MEA sulfosuccinic acid, stearamide MEA sulfosuccinic acid, stearyl sulfosuccinamic acid, tallamido MEA sulfosuccinic acid, tallowamide MEA sulfosuccinic acid, undecyl enamide MEA sulfosuccinic acid, undecyl enamide PEG-2 sulfosuccinic acid, wheat gelamide MEA sulfosuccinic acid, and wheat gelamide PEG-2 sulfosuccinic acid.

[0122] Some examples of commercially available sulfonates are AEROSOL® OT-S, AEROSOL® OT-MSO, AEROSOL® TR 70% (Cytec Inc., West Paterson, NJ), NaSul CA-HT3 (King Industries, Norwalk, CT) and C500 (Crompton Co., West Hills, Ontario, Canada). AEROSOL® OT-S is dioctyl sodium sulfosuccinate in petroleum distillate. AEROSOL® OT-MSO also contains dioctyl sodium sulfosuccinate. AEROSOL® TR 70% is bistridecyl sodium sulfosuccinate in a mixture of ethanol and water. NaSul CA-HT3 is a calcium dinonyl naphthalene sulfonate / carboxylate complex. C500 is an oil-soluble calcium sulfonate.

[0123] Alkyl or alkyl group refers to a saturated hydrocarbon having one or more carbon atoms, including straight chain alkyl groups (e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyloctyl, nonyl, decyl, etc.), cyclic alkyl groups (or cycloalkyl or alicyclic or carbocyclic groups) (e.g., cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, etc.), branched alkyl groups (e.g., isopropyl, tert-butyl, sec-butyl, isobutyl, etc.), and alkyl substituted alkyl groups (e.g., alkyl substituted cycloalkyl groups and cycloalkyl substituted alkyl groups).

[0124] Alkyl can include both unsubstituted and substituted alkyls. Substituted alkyl refers to an alkyl group having substituents replacing one or more hydrogens on one or more carbons of the hydrocarbon backbone. Such substituents may include alkenyl, alkynyl, halogeno, hydroxyl, alkylcarbonyloxy, arylcarbonyloxy, alkoxycarbonyloxy, aryloxy, aryloxycarbonyloxy, carboxylate, alkylcarbonyl, arylcarbonyl, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, alkylthiocarbonyl, alkoxy, phosphate, phosphonato, phosphinato, cyano, amino (including alkylamino, dialkylamino, arylamino, diarylamino and alkylarylamino), acylamino (including alkylcarbonylamino, arylcarbonylamino, carbamoyl and ureido), imino, sulfhydryl, alkylthio, arylthio, thiocarboxylate, sulfate, alkylsulfinyl, sulfonate, sulfamoyl, sulfonamido, nitro, trifluoromethyl, cyano, azido, heterocyclic, alkylaryl, or aromatic (including heteroaromatic) groups.

[0125] In some embodiments, substituted alkyls may include heterocyclic groups. Heterocyclic groups include closed ring structures analogous to carbocyclic groups, in which one or more of the carbon atoms in the ring is an element other than carbon, such as nitrogen, sulfur, or oxygen. Heterocyclic groups may be saturated or unsaturated. Exemplary heterocyclic groups include aziridine, ethylene oxide (epoxide, oxirane), thiirane (episulfide), dioxirane, azetidine, oxetane, thietane, dioxetane, didiethane, dithiete, azolidine, pyrrolidine, pyrroline, oxolane, dihydrofuran, and furan.

[0126] For anionic surfactants, the counterion is typically sodium, but may alternatively be potassium, lithium, calcium, magnesium, ammonium, amines (primary, secondary, tertiary or quaternary) or other organic bases. Exemplary amines include isopropylamine, ethanolamine, diethanolamine, and triethanolamine. Mixtures of the above cations may also be used.

[0127] The surfactant used in the preparation of the material of the present disclosure can be cationic. Such cationic surfactants include, but are not limited to, pyridine-containing compounds, and primary, secondary, tertiary or quaternary organic amines. For cationic surfactants, the counter ion can be, for example, chloride, bromide, methosulfate, ethosulfate, lactate, saccharinate, acetate and phosphate. Examples of cationic amines include polyethoxylated oleyl / stearylamine, ethoxylated tallow amine, cocoalkylamine, oleylamine, and tallow alkylamine, and mixtures thereof.

[0128] Examples of quaternary amines with a single long chain alkyl group are cetyltrimethylammonium bromide (CTAB), benzyldodecyldimethylammonium bromide (BddaBr), benzyldimethylhexadecylammonium chloride (BdhaCl), dodecyltrimethylammonium bromide, myristyltrimethylammonium bromide, stearyldimethylbenzylammonium chloride, oleyldimethylbenzylammonium chloride, lauryltrimethylammonium methosulfate (also known as cocotrimonium methosulfate), cetyldimethylhydroxyethylammonium bromide, and tetramethylammonium bromide. The active ingredients are ammonium dihydrogen phosphate, bassuamidopropylkonium chloride, cocotrimonium chloride, distearyldimonium chloride, wheat germamidopropalkonium chloride, stearyl octyldimonium methosulfate, isostearaminopropalkonium chloride, dihydroxypropyl PEG-5 linoleaminonium chloride, PEG-2 stearmonium chloride, behentrimonium chloride, dicetyldimonium chloride, tallowtrimonium chloride and behenamidopropyl ethyldimonium ethosulfate.

[0129] Examples of quaternary amines with two long chain alkyl groups are didodecyldimethylammonium bromide (DDAB), distearyldimonium chloride, dicetyldimonium chloride, stearyloctyldimonium methosulfate, dihydrogenated palmoylethyl hydroxyethylmonium methosulfate, dipalmitoylethyl hydroxyethylmonium methosulfate, dioleylethyl hydroxyethylmonium methosulfate, and hydroxypropyl bisstearyldimonium chloride.

[0130] Quaternary ammonium compounds of imidazoline derivatives include, for example, isostearyl benzylimidonium chloride, cocoyl benzyl hydroxyethyl imidazolium chloride, cocoyl hydroxyethyl imidazolium PG chloride phosphate, and stearyl hydroxyethylimidonium chloride. Other heterocyclic quaternary ammonium compounds, such as dodecyl pyridinium chloride, amprolium hydrochloride (AH), and benzethonium hydrochloride (BH), may also be used.

[0131] The surfactants used in the preparation of the materials of the present disclosure may be non-ionic and include, but are not limited to, polyalkylene oxide carboxylates, fatty acid esters, fatty alcohols, ethoxylated fatty alcohols, poloxamers, alkanolamides, alkoxylated alkanolamides, polyethylene glycol monoalkyl ethers, and alkyl polysaccharides. The polyalkylene oxide carboxylates have one or more carboxylate ester moieties, each of which has about 8-20 carbons and a polyalkylene oxide moiety containing about 5-200 alkylene oxide units. The ethoxylated fatty alcohols include an ethylene oxide moiety, each of which contains about 5-150 ethylene oxide units and a fatty alcohol moiety having about 6-30 carbons. The fatty alcohol moiety may be cyclic, linear or branched, and may be saturated or unsaturated. Some examples of ethoxylated fatty alcohols include ethylene glycol ethers of oleic alcohol, steareth alcohol, lauryl alcohol, and isocetyl alcohol. Poloxamers are block copolymers of ethylene oxide and propylene oxide, having about 15 to about 100 moles of ethylene oxide. Alkyl polysaccharide (APS) surfactants (e.g., alkyl polyglycosides) contain a hydrophobic group having about 6 to about 30 carbons and a polysaccharide (e.g., polyglycoside) as the hydrophilic group. An example of a commercially available nonionic surfactant is FOA-5 (Octel Starreon LLC., Littleton, Colorado).

[0132] Specific examples of suitable nonionic surfactants include alkanolamides such as cocamide diethanolamide (DEA), cocamide monoethanolamide (MEA), cocamide monoisopropanolamide (MIPA), PEG-5 cocamide MEA, lauramide DEA, and lauramide MEA; alkylamine oxides such as lauramide oxide, cocamide oxide, cocamidopropylamine oxide, and lauramidopropylamide oxide; sorbitan laurate, sorbitan distearate, fatty acids or fatty acid esters such as lauric acid, isostearic acid, and PEG-150 distearate; fatty alcohols or ethoxylated fatty alcohols such as lauryl alcohol, alkyl polyglycosides such as decyl glucoside, lauryl glucoside, and coco glucoside.

[0133] Surfactants used in the preparation of the materials of the present disclosure may be zwitterionic, having both formal positive and negative charges in the same molecule. The positively charged group may be a quaternary ammonium, phosphonium, or sulfonium, and the negatively charged group may be a carboxylate, sulfonate, sulfate, phosphate, or phosphonate. As with other classes of surfactants, the hydrophobic moiety may contain one or more long, linear, cyclic, or branched aliphatic chains of about 8 to 18 carbon atoms. Specific examples of zwitterionic surfactants include alkyl betaines such as cocodimethyl carboxymethyl betaine, lauryl dimethyl carboxymethyl betaine, lauryl dimethyl alpha-carboxyethyl betaine, cetyl dimethyl carboxymethyl betaine, lauryl bis-(2-hydroxyethyl) carboxymethyl betaine, stearyl bis-(2-hydroxypropyl) carboxymethyl betaine, oleyl dimethyl gamma-carboxypropyl betaine, and lauryl bis-(2-hydroxypropyl) alpha carboxy-ethyl betaine, amidopropyl betaine; alkyl sultaines such as cocodimethyl sulfopropyl betaine, stearyl dimethyl sulfopropyl betaine, lauryl dimethyl sulfoethyl betaine, lauryl bis-(2-hydroxyethyl) sulfopropyl betaine, and alkyl amidopropyl hydroxysultaine.

[0134] The surfactant used in the preparation of the material of the present disclosure can be amphoteric.Examples of suitable amphoteric surfactants include ammonium or substituted ammonium salts of alkyl amphocarboxyglycinate and alkyl amphocarboxypropionate, alkyl amphodipropionate, alkyl amphodiacetate, alkyl amphoglycinate, and alkyl amphopropionate, as well as alkyl iminopropionate, alkyl iminodipropionate, and alkyl amphopropylsulfonate.Specific examples are cocoamphoacetate, cocoamphopropionate, cocoamphodiacetate, lauroamphoacetate, lauroamphodiacetate, lauroamphodipropionate, lauroamphodiacetate, cocoamphopropylsulfonate, caproamphodiacetate, caproamphoacetate, caproamphodipropionate, and stearic acid amphoacetate.

[0135] Surfactants used in preparing the materials of the present disclosure can also be polymers such as, for example, N-substituted polyisobutenyl succinimides and succinates, alkyl methacrylate vinylpyrrolidone copolymers, alkyl methacrylate-dialkylaminoethyl methacrylate copolymers, alkyl methacrylate polyethylene glycol methacrylate copolymers, polystearamides, and polyethyleneimines.

[0136] Additionally, the surfactant used in preparing the materials of the present disclosure may be a polysorbate-type non-ionic surfactant, such as, for example, polyoxyethylene (20) sorbitan monolaurate (polysorbate 20), polyoxyethylene (20) sorbitan monopalmitate (polysorbate 40), polyoxyethylene (20) sorbitan monostearate (polysorbate 60) or polyoxyethylene (20) sorbitan monooleate (polysorbate 80).

[0137] The surfactants used in the preparation of the materials of the present disclosure can be oil-based dispersions, including alkyl succinimides, succinate esters, high molecular weight amines, as well as Mannich bases and phosphoric acid derivatives. Some specific examples are polyisobutenyl succinimide-polyethylene polyamines, polyisobutenyl succinic acid esters, polyisobutenyl hydroxybenzyl-polyethylene polyamines, and bis-hydroxypropyl phosphates.

[0138] The surfactants used in the preparation of the materials of the present disclosure can be a combination of two or more surfactants of the same or different types selected from the group consisting of anionic, cationic, nonionic, zwitterionic, and amphoteric and ampholytic surfactants. Suitable examples of combinations of two or more surfactants of the same type include, but are not limited to, a mixture of two anionic surfactants, a mixture of three anionic surfactants, a mixture of four anionic surfactants, a mixture of two cationic surfactants, a mixture of three cationic surfactants, a mixture of four cationic surfactants, a mixture of two nonionic surfactants, a mixture of three nonionic surfactants, a mixture of four nonionic surfactants, a mixture of two zwitterionic surfactants, a mixture of three zwitterionic surfactants, a mixture of four zwitterionic surfactants, a mixture of two amphoteric surfactants, a mixture of three amphoteric surfactants, a mixture of four amphoteric surfactants, a mixture of two ampholytic surfactants, a mixture of three ampholytic surfactants, and a mixture of four ampholytic surfactants.

[0139] Thin Polymer Layer Materials The techniques described above involve the use of polymers to form surface treatments 201 on high aspect ratio carbon nanotubes to promote adhesion with active material particles 300. Although several convenient and suitable polymers have been described, it will be understood that other polymeric materials may be used, including the following:

[0140] The polymer used in the preparation of the materials of the present disclosure can be a polymeric material, such as a water-processable polymeric material. In various embodiments, the following polymers (and combinations thereof) can be used: polyacrylic acid (PAA), poly(vinyl alcohol) (PVA), poly(vinyl acetate) (PVAc), polyacrylonitrile (PAN), polyisoprene (PIpr), polyaniline (PANi), polyethylene (PE), polyimide (PI), polystyrene (PS), polyurethane (PU), polyvinyl butyral (PVB), polyvinylpyrrolidone (PVP). In some embodiments, another exemplary polymeric material is fluorine acrylic hybrid latex (TDR202A), supplied by JSR Corporation. EXAMPLES

[0141] The following non-limiting examples further illustrate the application of the teachings of the present disclosure. In the following examples, the term "binder-free" or "binderless" electrodes refer to the type of electrodes detailed above that are characterized by a 3D matrix or scaffold of high aspect ratio carbon on which is present a surface treatment that promotes adhesion of active material to the scaffold without a bulk polymeric binder, such as PVDF.

[0142] As used below, the term C-rate refers to a measure of the rate at which a battery is discharged relative to its maximum capacity. A 1C rate means that the discharge current will discharge a full battery in 1 hour. For a battery with a capacity of 100 amp-hours, this equates to a discharge current of 100 amps.

[0143] Example 1 - Electric Vehicle Battery Cell The following battery cell is suitable for use in electric vehicles (EVs). The cell combines cathode and anode technologies of the type described herein, for example, for use in EV applications. Key high-level advantages include lower manufacturing costs, higher energy density, excellent power density, and a wide operating temperature range. These advantages stem from the approach for battery electrode manufacturing described herein, which eliminates PVDF polymer binders and toxic solvents such as N-methyl-2-pyrrolidone (NMP). This results in substantial performance advantages in range, charge rate, and driving end users to manufacturing processes that offer lower costs, less capital intensiveness, and greater safety for battery manufacturers.

[0144] The teachings herein provide a technology platform for producing electrodes for energy storage that may exhibit the following advantages: reduction in manufacturing cost and resulting LiB dollars / kWh, increase in energy density by combining a cathode with a thick coating and a high capacity anode featuring high performance active materials such as Si or SiOx, fast charging. The teachings herein provide a scalable technology for improving power density in energy storage by removing traditional polymer binders from active material coatings.

[0145] Conventional LiB electrodes are made by mixing active materials, conductive additives and polymer binders in a slurry. Conventional cathodes are manufactured using NMP-based slurries and PVDF polymer binders. Such binders have high molecular weights and promote adhesion to the current collector foil and aggregation of active material particles by two main mechanisms: 1) entanglement (or intertwining or entanglement) promoted by long polymer chains, and 2) hydrogen bonding between the polymer, active material and current collector. However, the polymer binder-based method has significant disadvantages in terms of performance: power density, energy density, and also in terms of manufacturing costs.

[0146] The teachings herein provide electrodes that do not have a PVDF binder in the cathode or other conventional (or conventional) binders in the anode. Instead, as detailed above, a 3D carbon skeleton or matrix holds the active material particles together to form a cohesive layer that also adheres tightly to the metal current collector. Such an active material structure is formed during the slurry preparation and subsequent roll-to-roll ("R2R") coating and drying process. One of the major advantages of this technology is its scalability and "drop-in" (or part replacement) nature by being compatible with conventional electrode manufacturing processes.

[0147] The 3D carbon matrix is ​​formed during slurry preparation using the techniques described herein: for example, using a two-step slurry preparation process (such as the type described above with reference to FIG. 6), high aspect ratio carbon materials are appropriately dispersed and chemically functionalized. The chemical functionalization is designed such that organized self-assembled structures are formed with the surfaces of the active material particles (e.g., NMC particles when used in the cathode, or silicon particles ("Si") or silicon oxide ("SiOx") particles in the case of the anode). The slurries so formed can be based on alcohol solvents for the cathode and water for the anode, and such solvents are very easily evaporated and handled during the manufacturing process. Electrostatic interactions promote the self-assembled structures in the slurry, and after the drying process, the 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) as well as the strong entanglement of the active material in the carbon matrix.

[0148] As will be appreciated by those skilled in the art, the mechanical properties of the electrodes can be easily modified depending on the application and mass loading requirements by tuning surface functionalization versus entanglement effects.

[0149] After coating and drying, the electrode is subjected to a calendaring process to control the density and porosity (or porosity) of the active material. For NMC cathode electrodes, densities of 3.5 g / cc or more and porosities of 20% or more can be obtained. 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.

[0150] In some typical applications, it can provide up to 20% reduction in dollars / kWh. By using friendly solvents that are easy to evaporate, the throughput (or production capacity) of the electrodes is higher, and more importantly, the energy consumption due to long dryers is significantly reduced. Also, the conventional NMP recovery system is much simpler when using alcohol or other solvent mixtures.

[0151] The teachings described herein provide a 3D matrix that dramatically improves electrode conductivity by 10 to 100 times compared to electrodes using conventional binders such as PVDF, which allows for rapid charging at battery levels. This technology allows for thick electrode coatings in the cathode, up to 150 μm (and greater) per side of the current collector. The solvents used in the slurry with the robust 3D carbon matrix are designed to achieve a thick wet coating without cracking during the drying process. A thick cathode used with a high capacity anode allows for a substantial jump in energy density, reaching 400 Wh / kg or more.

[0152] Fast charging is achieved by combining a high capacity anode that is lithiated via an alloying process (Si / SiOx) and by reducing the total impedance of the cell when the anode and cathode are combined as described herein. The teachings herein provide fast charging by having a highly conductive electrode and in particular a highly conductive cathode electrode.

[0153] One exemplary embodiment includes a Li-ion battery energy storage device in pouch cell form combining Ni-rich NMC active material in the cathode and a blend of SiOx and graphite active material in the anode, both of which are fabricated using the 3D carbon matrix process described herein.

[0154] A schematic of the electrode arrangement pouch cell device is shown in Figure 7. As shown, a double-sided cathode using a polymeric binder-free cathode layer on opposing sides of an aluminum foil current collector is arranged between two single-sided anodes, each having a polymeric binder-free anode layer arranged on a copper foil current collector. The electrodes are separated by a permeable separator material (not shown) that is wetted with the electrolyte (not shown). This configuration is housed in a pouch cell of a type well known in the art.

[0155] These devices can be characterized by a high mass loading of Ni-rich NMC cathode electrode and its fabrication method: mass loading = 20-30 mg / cm 2 , specific capacity >210mAh / g. SiOx / graphite anode (SiOx content = ~20 wt%) based electrode and its material synthesis and manufacturing method: mass loading 8-14mg / cm 2 , reversible specific capacity ≥ 550mAh / g. Long life performance, especially for SiOx / graphite anode based Li-ion based battery electrodes: -30℃ to 60℃. High energy, high power density, and long cycle life Ni-rich cathode / SiOx+graphite / carbon+ based Li-ion battery pouch cells: capacity ≥ 5Ah, specific energy ≥ 300Wh / kg, energy density ≥ 800Wh / L, cycle life ≥ 500 cycles under 1C rate charge / discharge, and ultra-high power rapid charge / discharge C-rate (up to 5C rate) performance. A summary of the performance parameters of this type of pouch cell is summarized in Figure 8.

[0156] Example 2 - Comparative performance of NMC811 Li-ion battery As discussed above, the teachings herein provide electrodes constructed with advanced 3D high aspect ratio carbon bond structures that eliminate the need for polymer binders and provide higher power, energy density (e.g., via thicker electrodes and higher mass loading of active material), and performance in harsh environments compared to traditional battery electrode designs. High performance Li-ion battery energy storage devices are designed and fabricated with optimized capacity ratio designs of binder-free cathode / anode electrodes, anode electrode prelithiation, and wide operating temperature electrolyte (e.g., −30° C. to 60° C.), and optimized test formation processes.

[0157] As described herein, the electrodes are fabricated with the complete exclusion of high molecular weight polymers, such as PVDF, and toxic NMP solvent from the active material layer. This dramatically improves LiB performance while reducing manufacturing costs and capital investments associated with mixing, coating and drying, NMP solvent recovery, and calendaring. In the electrode embodiment, the 3D nanoscale carbon matrix acts as a mechanical skeleton for the electrode active material and mimics the entanglement of polymer chains. Also, chemical bonds exist between the carbon surface, active material, and current collector, promoting adhesion and cohesion. However, unlike polymers, the 3D nanoscale carbon matrix is ​​highly electrically conductive, which allows for very high power (high C-rate). Also, this skeleton structure is more suitable for providing thick electrode active material, which is a powerful way to increase the energy density of LiB cells.

[0158] In this example, a binder-free cathode featuring NMC811 as the active material and incorporated into a lithium-ion battery (LIB) was fabricated according to the teachings of the present disclosure. The cell used a conventional type of graphite anode known in the art. The cell was constructed using the parameters summarized in FIG. 9, as described above with reference to FIG. 7. A conventional electrolyte was used, consisting of 1 M LiPF6 in a solvent mixture of ethylene carbonate and dimethyl carbonate with 1 wt. % vinyl carbonate additive. For comparison, an identical cell was fabricated, except that a PVDF binder-based cathode was used. The cell performance was compared as described below, which showed a clear advantage for the binder-free cathode cell.

[0159] As shown in the results summarized in Figure 10, the binder-free cell achieves a specific energy as high as 320Wh / kg based on a 20Ah battery cell design and a graphite anode with a cycle life of over 2000 cycles under 2C rate charge / discharge. In comparison, conventional binder-based cathode cells only reach a specific energy of 100-250Wh / kg at the cell level.

[0160] The binder-free cathode cell exhibits ultra-high power rapid charge / discharge C-rates up to 5C rate with over 50% capacity retention. Figure 10 shows a comparison of charge / discharge curves at various C-rates for the binder-free cathode cell (left) and the conventional binder-based cathode cell (right). The charge / discharge curves of the binder-free cathode cell show over 60% capacity retention at 5C rate combined charge / discharge. Thus, separate discharge or charge will show higher capacity retention. For example, in the condition of using a conventional graphite anode, it is noted that initial experimental results show that a 10C charge rate is achieved when a Si-dominant anode is combined with the NMC811 cathode used in this example.

[0161] Figure 11 shows a comparison of the cycle life of the above cells. The cells were cycled between voltages of 2.75 V and 4.2 V at 25°C and the discharge capacity was recorded. The binder-free cathode cell shows a life of over 2000 cycles with less than 20% discharge capacity loss. In contrast, the binder-based cathode cell shows more than 20% discharge capacity loss after only 1000 cycles.

[0162] Example 3 - Pouch half-cell comparison Binder-free cathode electrodes of the type described herein advantageously achieve high mass loadings, e.g., 45 mg / cm per side of NMC811 active material. 2 This example describes experimental results that show the performance of such high mass-loading binder-free electrodes compared to a control electrode featuring a PVDF binder and NMC811 active material.

[0163] For comparison purposes, half-cells of the type shown in Figure 12 were constructed with single-sided cathodes (both binder-free and binder-based controls) and lithium foil on a copper substrate as the counter electrode for the cell. The half-cells were subjected to charge rate testing under various current densities, with the results summarized below.

[0164] FIG. 13 shows the specific capacity versus potential (Li / Li) at various current densities for the binder-free cathode half-cell (solid trace) and the reference binder-based cathode half-cell (dotted trace). + 1 is a plot showing the change in potential (with potential as reference) over time at all current densities (and therefore all C-rates) where the binder-free cathode half-cell shows superior performance (as indicated by the shift of the traces further to the right).

[0165] FIG. 14 shows the volumetric capacity versus potential (Li / Li) at various current densities for a binder-free cathode half-cell (solid trace) and a reference binder-based cathode half-cell (dotted trace). +1 is a plot showing the change in potential (with potential as reference) over time at all current densities (and therefore all C-rates) for the binder-free cathode half-cell, which shows superior performance (as indicated by the shift in the traces to the right).

[0166] Figure 15 is a plot of volumetric capacity versus current density for a binder-free cathode half-cell (top trace) and a reference binder-based cathode half-cell (bottom trace). At all current densities (and therefore all C-rates), the binder-free cathode half-cell shows superior performance, with the comparative performance gap becoming larger at higher C-rates.

[0167] Figure 16 shows Nyquist plots obtained by electrochemical impedance spectroscopy for several vanadium-free cathode half-cells (circle, square and triangle traces) and a reference vanadium-based cathode half-cell. The vanadium-free cathode half-cells show significantly better performance than the reference cell.

[0168] From the figure, the current density is 0.5 to 10 mA / cm 2 When the discharge rate was increased to 1.2C, the discharge capacity retention of the vanader-free NMC811 electrode was increased compared to the vanader-based PVDF control NMC811 electrode, with both electrodes retaining the same 45mg / cm 2 It can be seen that the C-rate performance under various current densities is shown as a relative comparison between the conventional binder-based PVDF cathode and the binder-free cathode, and does not reflect the complete C-rate performance in a full cell configuration (e.g., as shown in Examples 1 and 2 above).

[0169] Example 4 The electrode technology described herein can dramatically improve the performance of energy storage devices such as batteries, ultracapacitors, etc. Using certain materials and low-cost processes, the disclosed electrodes can be formed with advanced 3D nanoscale geometries (e.g., also referred to as the technology disclosed herein). The resulting products provide greater power, energy density, and performance in harsh environments compared to traditional energy storage designs. Battery and supercapacitor manufacturers can utilize the disclosed electrodes to optimize their manufacturing processes, aiding in productivity growth, reducing costs, and increasing compatibility with the most active materials, including recent anode and cathode materials, such as Ni-rich NMC, silicon-based anodes, and solid electrodes. In some embodiments, the disclosed electrodes are binder-free or substantially binder-free. With the development of the disclosed binder-free electrode manufacturing process, the disclosed electrode technology can be implemented in conjunction with Li-ion battery applications to achieve fundamental advantages that reduce costs and improve critical performance aspects required by automotive OEMs and battery manufacturers.

[0170] Various embodiments include low cost and fast charging (LCFC) EV battery cells that can meet or exceed several electric vehicle industry goals, such as critical USAC technology goals. In some embodiments, the cells combine the disclosed cathode and anode technologies for fast charging EV applications. Key high level benefits of using the disclosed cathode and anode technologies include low manufacturing costs, high energy density, excellent power density, and operation over a wide temperature range. These benefits come from a new approach to manufacturing battery electrodes that eliminates the use of PVDF (polyvinylidene fluoride) polymer binders and toxic solvents such as N-methyl-2-pyrrolidone (NMP). Thus, various embodiments provide substantial performance advantages in range, charging speed, and facilitating end users to manufacturing processes that offer lower costs, less capital intensiveness, and greater safety for battery manufacturers.

[0171] Various aspects include, for example, high performance LCFC EV battery cells, including: (1) development of a high specific capacity cathode electrode; (2) development of a Si-dominant anode electrode; (3) development of an electrolyte formulation that improves 50° C. calendar life and cycle life; (4) development of an LCFC-EV65Ah battery cell design and manufacturing process; and (5) LCFC-EV65Ah battery cell qualifications.

[0172] This technology facilitates: - Reduction in LiB manufacturing costs and dollars / kWh Increased energy density by combining a cathode with a thick coating with a high capacity anode, e.g. Si, Si-C or SiOx -Improved fast charging capabilities This includes scalable technology to improve current density in energy storage by removing (or reducing) traditional polymer binders from active material coatings. In some embodiments, the electrodes include a nominal amount of polymer binder. In some embodiments, the electrodes do not include polymer binders, i.e., are polymer binder-free.

[0173] Related art electrodes for LiBs are typically made by mixing active material, conductive additives, and polymer binders in a slurry. Related art cathodes are typically fabricated using NMP-based slurries and PVDF polymer binders. Such binders have very high molecular weights and promote the cohesiveness of active material particles and their attachment to the current collector foil by two main mechanisms: 1) entanglement promoted by long polymer chains, and 2) hydrogen bonding between the polymer, active material, and current collector. However, this polymer binder-based method presents significant drawbacks in performance (current density, energy density) and manufacturing costs.

[0174] According to various embodiments, these electrodes have no PVDF binder in the cathode and a reduced amount of binder in the silicon-dominant anode. In some embodiments, these electrodes include a 3D carbon matrix that holds the active material particles together to form a cohesive layer that also adheres tightly to the metal current collector. Such active material structure is formed during the slurry preparation and subsequent R2R coating and drying steps. The advantage of this technology is, in some embodiments, its scalability and "drop-in" nature since it is based on conventional electrode manufacturing processes.

[0175] The 3D carbon matrix is ​​formed during the slurry preparation: high aspect ratio 1D and 2D carbon materials are appropriately dispersed and chemically functionalized using a two-step proprietary preparation process. The chemical functionalization is designed to form organized self-assembled structures with the surface of the active material particles (e.g., NMC particles or Si / SiOx particles). The slurries thus formed are usually based on alcohol solvents for the cathode and water for the anode, and are very easy to evaporate and handle. Electrostatic interactions promote the self-assembled structures in the slurry, and after the drying process, the bonding between the carbon matrix with the so-formed active material particles and the surface of the current collector is promoted by the surface functional groups as well as strong entanglement.

[0176] The mechanical properties of the electrodes can be tailored to suit the application, as can the mass loading requirements by tuning the surface functional groups versus entanglement effects.

[0177] In some embodiments, after coating and drying, the electrode can be subjected to a calendaring process to control the density and porosity of the active material. For Ni-rich NMC cathode electrodes, densities ≧3.5g / cc and ≦20% porosity can be achieved. Depending on the mass loading and LIB cell requirements, the porosity can be optimized. In some embodiments, for SiOx / Si anodes, the porosity can be specifically controlled to accommodate the expansion of the active material during the lithiation process.

[0178] According to various embodiments, the manufacturing / electrode design-related implementation of this technology can result in up to 18% reduction in dollars / kWh. By using friendly solvents that are easily evaporated, the electrode throughput is higher, and more importantly, the energy consumption due to long dryers is significantly reduced. Also, the conventional NMP recovery system is much simpler when using alcohol or other solvent mixtures.

[0179] The 3D matrix dramatically improves the electrode conductivity by 10 to 100 times, which allows for rapid charging at battery levels. This technology allows for thick electrode coatings in the cathode (up to 150 μm per side of the current collector). The solvent used in the slurry with the robust 3D carbon matrix is ​​designed to achieve a thick wet coating without cracking during the drying process. According to various embodiments, the relatively thick cathode combined with the high capacity anode allows for a substantial jump in energy density. For example, the energy density can reach 400 Wh / kg. In some embodiments, the energy storage device exhibits an energy density of 400 Wh / kg or less. In some embodiments, the energy storage device exhibits an energy density of more than 400 Wh / kg. In some embodiments, the energy storage device exhibits an energy density of 330 Wh / kg or more.

[0180] This technology has a unique approach to fast charging, which is achieved by combining a high specific capacity anode that is lithiated via an alloying process (Si / SiOx) and by reducing the total impedance of the cell when the anode and cathode made by these methods with the disclosed materials are combined. In addition to the Si-dominant anode, the technology reduces the cell impedance by having a highly conductive electrode and especially a highly conductive cathode electrode. In addition, the electrode technology can reduce the resistance of ion transport and charge transfer for the battery cathode and anode electrodes.

[0181] According to various embodiments, a Li-ion battery energy storage device ("pouch cell") includes a Ni-rich NMC / NCMA (or other new type) cathode and a Si-dominant (Si elemental weight %≧50%) anode. Various embodiments relate to energy storage devices that exhibit one or more of the following: 1) LCFC-EV battery cell capacity at beginning of life ("BOL") ≥ 65Ah 2) LCFC-EV battery energy density at BOL: ≥ 330Wh / kg, ≥ 800Wh / L 3) LCFC-EV battery fast charging: 80% SOC in 15 minutes 4) LCFC-EV battery DST cycle life with C / 3 charging at 30℃: 1000 cycles with C / 3 capacity retention ≥ 80% 5) LCFC-EV battery DST cycle life with ≧3.5C fast charging at 30℃: 1000 cycles at C / 3 capacity retention ≧80% 6)LCFC-EV battery calendar life at 30℃: ≥ 10 years 7) LCFC-EV battery cost at BOL ≦ $79 / kWh

[0182] TIFF2024530540000002.tif67158

[0183] According to various aspects, a full battery cell is developed and evaluated in terms of its power performance, cost, rechargeability, required infrastructure, and commercial feasibility. The evaluation is based on guidelines set forth by USABC and follows a series of tests to characterize the performance and life behavior of the battery application, including voltage limits, temperature control, pressure control, battery size, and charging procedures.

[0184] According to various embodiments, this technology is reinvented to fabricate energy storage devices (e.g., energy storage devices used in EVs) by completely removing high molecular weight polymers, e.g., PVDF, and toxic NMP solvent from the active material layer. By realizing electrodes by removing high molecular weight polymers, e.g., PVDF, and toxic NMP solvent from the active material layer, LiB performance is dramatically improved while reducing manufacturing costs and capital investments associated with mixing, coating and drying, NMP solvent recovery, and calendaring.

[0185] In these electrodes, the 3D nanoscale carbon matrix acts as a mechanical skeleton for the electrode active material and mimics the entanglement of polymer chains. Also, chemical bonds exist between the carbon surface, the active material, and the current collector, promoting adhesion and cohesion. However, unlike polymers, the 3D nanoscale carbon matrix is ​​highly electrically conductive, which allows for very high power (high C-rate) rapid charging and discharging. This skeleton structure is also more suitable for providing thick electrode active material layers, which is a powerful way to increase the energy density of LiB cells.

[0186] The manufacturing process of the electrode technology includes the following steps: According to various embodiments, the disclosed (NX) battery electrode manufacturing by roll-to-roll (R2R) slot die coating process is demonstrated. Figure 17 (bottom) shows the slot die coating process for NX NMC811 cathode electrode manufacturing and a roll of finished good quality NX NMC811 electrode (e.g., an electrode including the disclosed technology). For the NX Si-C anode, as can be seen from Figure 18, there is no issue using a slot die to coat the NX Si-C anode slurry, indicating that good quality NX Si-C anode electrodes can be manufactured and reproducibly.

[0187] FIG. 19 shows a summary of mechanical adhesion tests for both NX NMC811 and Si-C electrodes. FIG. 19 shows that adhesion was 5.6 mAh / cm 2The loads shown are comparable between the NX NM811 and PVDF control NMC811 cathode electrodes. Both are in the average range of 150-170 N / m, indicating that the NX NM811 can achieve similar mechanical performance as the PVDF control NMC811 electrode. ~6.2 mAh / cm 2 For the loaded NX Si-C anode, the average adhesion force is about 235N / m, which passes the 2mm mandrel test. The thickness of the NX Si-C anode electrode is much thinner than that of NX NMC811, which can achieve higher energy density for Li-ion batteries.

[0188] To test the electrochemical performance of the electrodes, half and full cells, both of which are pouch cell types, were analyzed. The pouch cell structures for both half and full cells are shown in Figure 20. Figure 21 shows the results of the half cell (NX cathode vs Li / Li) based on various cathode active materials in NX and a PVDF control. + ) shows the initial first cycle charge-discharge specific capacity and fast charge C-rate performance. As can be seen from FIG. 21, the NX NMC811 cathode electrode shows the highest initial coulombic efficiency (ICE) among all half-cell test results, which reaches ∼95.7%. The initial discharge specific capacity for the NX NMC811 is about ∼210 mAh / g, based on the active layer weight (not the active material) including the NX nanocarbon weight in the calculation. The PVDF control NMC shows a much lower ICE, which is 88.8%, and the specific capacity is less than 200 mAh / g.

[0189] As can be seen from FIG. 21, the cathode half-cell fast charging C-rate performance is 5.6 mAh / cm 2 The load NX NMC811 can achieve 77.3% constant current (CC) region capacity retention under 3.4C rate fast charging compared to 0.1C rate charging, while 5.2mAh / cm 2The loaded PVDF control NMC811 could only maintain 35.9% CC region capacity retention under 3.4C rate fast charging, demonstrating that the NX NMC811 cathode electrode technology can improve the fast charging capability by >2 times compared to the conventional PVDF binder-based NMC811 electrode in half cells using Li as the counter electrode.

[0190] To further evaluate the performance of the NX Si-C anode electrode, a full pouch cell with an NX NMC811 / NCMA cathode and an NX Si-C anode was assembled and the fast charging performance was evaluated. + Based on the test results (1.2V~1mV), the initial 1st Li charge specific capacity is about 1234mAh / g, and the 1st Li discharge specific capacity is about 1116mAh / g, based on the active layer weight (not active material) including NX nanocarbon weight. The initial ICE of NX Si-C anode is about ~90%.

[0191] FIG. 22 shows the fast charging performance for the NX NMC811 / NCMA||Si-C cell system. As can be seen from FIG. 22, the fast charging capacity of 5.6 mAh / cm 2 The load NX NMC♯2, combined with NX Si-C anode, shows the best fast-charge performance. After 15 minutes of 3.5C rate CC-CV fast charging, the fast-charge capacity retention is >80% compared to the C / 3 CC-CV charge capacity in the 4.2~2.8V cell voltage range. This demonstrates that excellent fast-charge capability can be achieved after combining NX NMC811 and NX Si-C in a full-cell system.

[0192] FIG. 23 shows the life performance for NX NMC811||Si-C full battery cells. As can be seen from FIG. 23, NX battery cells can achieve >80% energy retention after 600 cycles 1C1C cycling and ∼70% after 1000 cycles 1C1C cycling at 30° C. For 50° C. SOC100 calendar life test, all types of electrolyte cells have approximately ∼80% capacity retention after 30 days. Various embodiments include electrolyte formulations optimized for 50° C. SOC100 calendar life performance improvement in this LCFC-EV battery development project.

[0193] After the electrochemical performance evaluation of the NX electrodes, standard R&D 1.5Ah battery cells were assembled using the NX electrodes. Table 1 (below) summarizes the NX NMC811||Si-C1.5AhLIB pouch cells. The NX NMC811 electrodes have a loading of 3.5g / cm 3 At a pressure density of about 5mAh / cm 2 areal loading. The N / P ratio for this batch of cells is about 1.10. The cell size is 46x46x3.4mm as shown below. As can be seen from Table 1, the ICE for the 1.5Ah cell is 90%-91%, respectively. The energy density is 325-329Wh / kg and 817-830Wh / L (SOC100), including stack and electrolyte, without considering the package, due to the small size of the cell format. If the stack total is increased for the cathode and anode electrodes to increase the cell capacity to >65Ah, the cell efficiency can be increased to ~95%. Also, the NX Si-C anode (5.3mg / cm 2 The mass loading was 24 mg / cm for a conventional graphite anode electrode. 2 16mg / cm to fit NX NMC811 cathode 2 It can be concluded that compared to the conventional POC, it improves the specific energy and energy density by >30% for the same R&D small format pouch cell and the same number of stacked electrode layers.

[0194] After evaluating the initial capacity and energy performance, 1C1C cycling performance at room temperature (RT) is carried out at two different voltage ranges: 4.2-2.8V and 4.2-3.0V. Excellent cycle life is achieved for the NX 1.5Ah cell. As can be seen from FIG. 24, the 1.5Ah cell can achieve ~90% energy retention after 500 cycles of 4.2-3.0V cycling under 1C1C and ~80% energy retention after 500 cycles of 4.2-2.8V cycling under 1C1C, respectively. This demonstrates that the NX NMC811||Si-C battery electrode technology can achieve stable cycling performance.

[0195] Various embodiments include a NX NMC811||Si-C9AhLIB pouch cell as shown in Figure 25. This 9Ah cell is constructed with 15 layers of NMC cathode electrodes and 16 layers of Si-C anode electrodes by a stacking cell manufacturing process. The NMC cathode mass loading is 3.12 g / cm 3 At a pressure density of about 26.5 mg / cm 2 and the Si-C anode mass loading is 1.47 g / cm 3 At a pressure density of about 5.4 mg / cm 2 . The N / P ratio of the battery cell is about 1.07-1.08. As can be seen from Fig. 25, the initial discharge capacity for the NX battery is about 9.1 Ah at ICE of 89.2%. The discharge energy is 31.2 Wh at 4.2-2.5 V and 29.8 Wh at 4.2-2.8 V.

[0196] FIG. 26 shows the 9Ah NX battery energy density calculation and drawings of the battery prototype. The energy density of the 9Ah NX battery prototype can achieve as high as 823Wh / L, which is >25% higher than the conventional (or run-of-the-mill) NMC622||graphite battery chemistry in the current industry. The current NX 9Ah pouch cell packaging efficiency is only ~86%. Therefore, in the LCFC-EV battery development project, for the larger than 65Ah cell design and manufacturing process, further development work will be carried out to increase the pouch cell packaging efficiency from 86% to ~95%.

[0197] After the initial capacity and energy evaluation of the 9Ah NX battery prototype, the volume expansion (thickness change) from SOC0 to SOC100 and fast charging capability are tested and evaluated. As can be concluded from Figure 27, the cell volume expansion is about 8.8% change when the cell is charged from SOC0 to SOC100, which is less than 10% volume expansion at the multi-layer cell level. After 3.5C rate CC-CV 15 minutes fast charging, the fast charging capacity retention is about 79.3% compared to the C / 3 CC-CV charging capacity. The R&D feasibility study process from 1.5Ah cell to 9Ah battery prototype demonstrates that there is no problem in scaling up Li-ion battery cells based on the NX NMC811||Si-C electrode technology and current Si-C anode active material chemistry.

[0198] According to various embodiments, the disclosed electrode technology can achieve an 18% reduction in dollars / kWh by reducing manufacturing costs, thereby reducing the required capital investments related to coating and calendaring equipment, and improving energy density. For coating equipment, the use of low boiling, chemically friendly, non-agglomerating solvents allows the slurry to dry more quickly, allowing roll-to-roll coating equipment with shorter ovens to be utilized. In addition, the solvent recovery system for these types of solvents can be simplified and less expensive than standard NMP recovery systems. The silicon-dominant anode design using SiOx and Si microparticles also contributes significantly to the reduction in dollars / kWh. According to various embodiments, compared to conventional battery technology, NMC811 and Si anodes (as disclosed herein) reduce dollars / kWh by 18%. The disclosed cathode process alone reduces costs by 12%.

[0199] In a Cairn Energy Research Advisors ERA (CairnERA) model, a 35 GWh factory in the US of this technology can produce lithium-ion batteries for $100.66 / kWh (COGS). With the implementation of the disclosed technology, the same factory can produce batteries for $82.59 / kWh. According to various embodiments, implementing the disclosed materials and manufacturing process technology results in a cost savings of $11.89 / kWh. An embodiment including the inclusion of 50% silicon content in the anode along with the disclosed technology can increase the cost savings to $18.07 / kWh. CairnERA projects the battery industry to grow to 706 GWh in 2025. These savings therefore represent a value of $8.4 billion to the battery industry. If 50% silicon content could be achieved with the disclosed technology, the global battery savings would be $12.8 billion. CairnERA has modeled several other battery manufacturing technologies. Other current technologies are unable to reduce the cost of battery manufacturing by more than $2, even in the most aggressive scenarios. The magnitude of potential savings with the disclosed process and electrode technology is unprecedented.

[0200] According to various aspects, implementations of the disclosed electrode technology exhibit the following: Both the disclosed NMC811 and Si-C anode battery electrode manufacturing processes were demonstrated by slot-die R2R coating and calendaring processes. The disclosed battery cell manufacturing process has been demonstrated with a standard Li-ion battery pouch cell manufacturing process. Without any development / optimization work, the disclosed battery electrodes showed excellent performance in terms of energy density (Wh / L), 1C1C cycle life, and 15 min 3.5C rate CC-CV fast charging.

[0201] Based on the points summarized above, Nanoramic has already demonstrated improvements on its electrode manufacturing technology side. Various aspects include the implementation of the disclosed technology showing: Development of Li-ion battery low cost and high capacity cathode active material (CAM) NCMA (Ni% ≥ 91%) or NCM307, for example, and Si anode active material (cheap $ / kWh and $ / kg) selection to improve battery cell energy, fast charging and cycle life performance. Development of electrolyte formulation to improve cycling performance and high temperature 50℃ SOC100 calendar life Large format ≥65Ah LCFC-EV battery cell design development, including packaging efficiency increase ≥95% and cell design modeling and manufacturing process development

[0202] Gap Table TIFF2024530540000003.tif217160

[0203] summary TIFF2024530540000004.tif65160

[0204] Various embodiments include Ni-rich NCMA (Ni%≧90%), cobalt-free (Co-free), and manganese (Mn)-rich low-cost cathode active materials. Ni-rich NCMA is one option with high specific capacity≧225-230mAh / g (reversible specific capacity) for high energy density and fast charging battery cells. Another CAM option is NCM307, which has an initial specific capacity of 270mAh / g at 92%-93% initial ICE. Potential vs Li / Li for NCM307 + The window can be increased from 4.7 to 2.5 V in combination with a high voltage electrolyte.

[0205] Various embodiments include optimization of NX cathode electrode formulations based at least in part on various CAM characteristics. The effect of various embodiment cathode formulations and processing parameters at 20-40 L batch sizes can be demonstrated through the use of a commercially available dispersive-planetary slurry mixing device.

[0206] According to various embodiments, high capacity loading ≥ 5.6 mAh / cm 2 A roll of NX cathode electrode can be produced by industrial manufacturing scale R2R slot die coating and calendering equipment. After the calendering process, the coating strength is ≥ 3.4-3.5g / cm 3 High press densities of 1000 to 2000 nm can be achieved, maximizing the energy density of the battery cell. The rheological properties of the resulting slurry are characterized and slot-die coating parameters are optimized to ensure high uniformity, coating speed, and yield from the coating process, and to ensure the commercial viability of the technology and its suitability for mass production EV market applications.

[0207] In some embodiments, the stability of the SEI in silicon-based anodes is essential for LiB cells to function. A number of different approaches to address the problems of expansion and cycling (or cyclic) stability of silicon-rich anodes have been utilized in the past two decades. However, two of the most popular approaches, optimized silicon oxide microparticles (SiOx) and nano-engineered silicon-carbon composite structures (particles, nanorods, etc.), are currently commercially uncompetitive against traditional graphite anodes for EV applications due to the cost of materials on a dollar / kWh basis. The cost in dollars / kg for both SiOx and nano-engineered silicon-carbon is still 10-20 times higher than graphite anode active materials. Micron-sized silicon particles (micro-Si) are commercially available at very low cost points (in the range of $7-10 / kg, which is comparable to graphite) while exhibiting specific capacity of +2000mAh / g from the material level. However, due to the large micron size of silicon particles, particle fracture leads to uncontrolled SEI surface growth and loss of electrical connection during cycling. These characteristics of micro-Si severely limit the application of the material where cycle stability and capacity retention are required. Materials, electrodes, and cell-level designs that can successfully prevent particle fracture and SEI growth in micro-Si should provide significant commercial opportunities by significantly increasing LiB cell energy without resorting to difficult-to-implement and commercially unproven technology concepts such as Li metal anode, sulfur cathode, and solid electrolyte cell designs, while simultaneously reducing cell-level cost on a dollar / kWh basis compared to cell designs containing competing silicon materials such as SiOx. The micro-Si selected and evaluated in this task does not require prelithiation, as the ICE for micro-Si materials is ≥93%-95%.

[0208] Various embodiments include a Si-dominant anode using commercially available off-the-shelf micro-silicon particles with particle sizes of 6-8 μm in combination with the disclosed electrode processing techniques as shown in FIG. 28 below. The electrolyte used in this study was the off-the-shelf electrolyte by FEC without special electrolyte development work. As can be seen from FIG. 28, the ICE for the NX NMC811||89% micro-Si battery system can achieve ∼95% without prelithiation. After the initial 100 cycles under 1C1C, the Si anode active layer specific capacity is higher than 1300 mAh / g, which is a very promising result for the micro-Si anode. The fast-charge C-rate performance results also show promising fast-charge performance up to 6C rate. Various embodiments improve the cycling performance of the micro-silicon dominant anode in combination with optimizing the energy storage device design based at least in part on the characteristics of some commercially available LiB-grade micro-silicon powders.

[0209] Nanoramic will evaluate three to five different grades of microsilicon materials from three major material manufacturers with various particle sizes / distributions and carbon surface treatments with the goal of determining the optimal particle morphology and surface characteristics that will provide the best coulombic efficiency when used with the disclosed 3D nanocarbon support matrix.

[0210] In various aspects, different types of Si anode active materials, including micro-Si, nano-Si and SiOx, as well as electrochemical test performances are compared.

[0211] Various aspects include optimizing the nanocarbon composite formulation using low-cost nanocarbon feedstock materials. The resulting silicon-dominant anode can contain up to 5 wt% nanocarbon matrix material, which can mechanically and electrically support up to 90 wt% silicon active material while retaining excellent mechanical and electrochemical properties. This is carried out using the disclosed techniques related to the NX nanocarbon dispersion and functionalization process. The entire process is carried out in a standard laboratory air environment and is insensitive to environmental factors and equipment setup, which can be very easily scaled up from the current kilogram-scale implementation in Nanoramics' equipment to ton-scale for commercial manufacturing.

[0212] This optimization process delivers a cost-effective nanocarbon matrix that enables a micro-silicon dominant anode with desirable electrochemical and mechanical stability through proven, scalable processing techniques developed with Nanoramics.The NX cathode || Si dominant anode full battery cost target based on the above material selection is ≦$79 / kWh, which is close to the cost target for the USAC LCFC-EV battery.

[0213] High load ≧6.2mAh / cm 2 Optimization of NX-Si-based anode electrode manufacturing process High capacity load ≧6.2mAh / cm 2 A roll of NX Si-dominant anode electrodes can be fabricated using industrial manufacturing scale R2R slot die coating and calendering equipment. The press density of the Si-dominant anode electrodes after the calendering process can be optimized to maximize the energy density and cycle life performance of the battery cells.

[0214] Development of Si-dominant anode electrolyte formulations Unlike the graphite anodes conventionally used in lithium-ion batteries, micro-Si exhibits significant volume expansion, which leads to material cracking and changes in electrode pore structure during charging and discharging. The solid electrolyte interface (SEI) generated from conventional carbonate electrolytes fails to accommodate the strain and stress of Si during lithiation, which is manifested by inhomogeneous lithiation resulting in consistently low cycling, SEI thickening, and rapid capacity fade. To solve these problems, the electrolytes according to various embodiments 1) effectively form a stable and low-resistance SEI in the initial cycle to avoid SEI thickening and inhomogeneous lithiation, and 2) easily wet the electrode to withstand the severe changes in electrode pore volume during cycling and enable full capacity utilization of micro-Si.

[0215] Various embodiments improve the SOC100 calendar life at 50°C and optimize the DST cycle life for both C / 3 and fast charging. Various embodiments include a high-performance electrolyte formulation system to form a mechanically robust and electrochemically stable solid electrolyte interface (SEI) layer on the Si-dominant anode particles. A carbonate-free room temperature ionic liquid (NC-RTIL) could be utilized as an additive to form a better SEI layer on the Si-dominant anode. The stability of the SEI layer is attributed to the chemical makeup of the NC-RTIL electrolyte and the resulting decomposition products. For example, the FSI in the proposed electrolyte system - The decomposition of the anion is F - The electrolyte releases LiF, which is known to improve the SEI stability. The initial preliminary cycle life test results shown in FIG. 29 demonstrate that the new type of electrolyte with RTIL additive can achieve a CE (coulombic efficiency)% value close to 100% in the first 90 cycles based on a NX89% micro-Si anode half cell (Li as counter electrode). After the first 90 cycles, the NX Si anode specific capacity is 50mV~1VvsLi / Li under 0.2C rate cycling. + And it can achieve ≧2250mAh / g.

[0216] Battery cell design and manufacturing process development for LCFC-EV≧65Ah disclosed: 1: 65Ah NX battery cell design, including electrode punching size, calculation of number of stacked layers, lead tab placement, and energy density calculation

[0217] 2: 65Ah NX battery multiphysics modeling and simulation to predict the electrical-chemical-thermal-mechanical behavior; the modeling focuses specifically on the fast charging capability and long term DST cycling performance of the battery cells.

[0218] The outline of the work is detailed below and specified in four parts: The first part is to establish a baseline model. Firstly, a baseline multi-physics coupled model is established, including a battery model describing the behavior of voltage, current and capacity, a solid mechanics model describing the behavior of deformation and stress generation, and a thermal model describing the temperature distribution and propagation behavior.

[0219] The second part is to validate the baseline model with the experimental data we obtained based on a 65Ah cell; the modeled deformation, temperature and voltage profiles (within one complete cycle of 0.1C, 0.33C and 3.5C, respectively) are analyzed and compared with the experimental data.

[0220] The third part is to model the cycling performance. The validated model is then used for cycling modeling under the same loading conditions as the experiment. The modeling results are compared with the experimental data to further validate the model. Based on the comparison, necessary modifications are made to improve the accuracy of the model.

[0221] The fourth part is a parametric study, which is carried out simultaneously with the third part. Based on the confirmed model, a series of parametric studies are carried out to study the effects of geometry, load density, and stacking pressure, etc., to provide guidance for battery design and optimization. 3: 65Ah NX battery manufacturing process development and optimization, including electrode punching, stacking, tab welding, three-sided heat sealing, electrolyte filling and vacuum sealing, forming and degassing, and final sealing and trimming, etc.

[0222] LCFC-EV≧65Ah NX Battery Cell Qualification: Li-ion battery pouch cell tests include: USABC Core Tests, Accelerated Calendar Tests, Cycle Life Tests [14A], and Reference Performance Tests (RPT) based on the USABC Battery Test Manual for Electric Vehicles. Detailed test plans are provided in Section 5 below.

[0223] 42 equivalent proposed 65Ah LCFC-EV batteries will be manufactured and 21 cells will be shipped to Idaho National Laboratory (INL) for cell performance evaluation. 30 months into the project (at the end), 42 equivalent proposed 65Ah LCFC-EV batteries will be manufactured and 21 cells will be shipped to Idaho National Laboratory (INL) for cell performance evaluation.

[0224] In various embodiments, technology disclosed in International Application No. PCT / US20 / 040943, a copy of which is incorporated herein by reference in its entirety, may be used in energy storage devices and / or electrodes for energy storage devices as disclosed herein.

[0225] In some embodiments, the device includes an electrode active layer including 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 hooked to the network; and a surface treatment on the surface of the high aspect ratio carbon elements, the surface treatment promoting adhesion between the high aspect ratio carbon elements and the active material particles. In some embodiments, the high aspect ratio carbon elements include elements each having two major dimensions and one minor dimension, the ratio of the length of each of the major dimensions to the length of the minor dimensions being at least 10 times. In some embodiments, the high aspect ratio carbon elements include elements each having two major dimensions and one minor dimension, the ratio of the length of each of the major dimensions to the length of the minor dimensions being at least 100 times. In some embodiments, the high aspect ratio carbon elements include elements each having two major dimensions and one minor dimension, the ratio of the length of each of the major dimensions to the length of the minor dimensions being at least 1000 times. In one embodiment, high aspect ratio carbon elements include elements each having two major dimensions and one minor dimension, with the ratio of the length of each of the major dimensions to the length of the minor dimension being at least 10,0000 times.

[0226] In some embodiments, the high aspect ratio carbon elements include elements each having one long dimension and two short dimensions, where the ratio of the length of each long dimension to the length of each short dimension is at least 10. In some embodiments, the high aspect ratio carbon elements include elements each having one long dimension and two short dimensions, where the ratio of the length of each long dimension to the length of each short dimension is at least 100. In some embodiments, the high aspect ratio carbon elements include elements each having one long dimension and two short dimensions, where the ratio of the length of each long dimension to the length of each short dimension is at least 1000. In some embodiments, the high aspect ratio carbon elements include elements each having one long dimension and two short dimensions, where the ratio of the length of each long dimension to the length of each short dimension is at least 10000.

[0227] In some embodiments, the high aspect ratio carbon elements comprise carbon nanotubes or carbon nanotube bundles. In some embodiments, the high aspect ratio carbon elements comprise graphene flakes. In some embodiments, the electrode active layer contains less than 10% by weight of a polymeric binder disposed in the void spaces. In some embodiments, the electrode active layer contains less than 1% by weight of a polymeric binder disposed in the void spaces. In some embodiments, the electrode active layer contains less than 1% by weight of a polymeric binder disposed in the void spaces. In some embodiments, the electrode active layer is substantially free of polymeric materials other than the surface treatment. In some embodiments, the electrode active layer is substantially free of polymeric materials.

[0228] In some embodiments, the surface treatment comprises a material that is soluble in a solvent having a boiling point less than 202° C. In some embodiments, the surface treatment comprises a material that is soluble in a solvent having a boiling point less than 185° C.

[0229] In some embodiments, during the formation of the active layer, the materials forming the surface treatment were dissolved in a solvent having a boiling point of less than 202° C. In some embodiments, during the formation of the active layer, the materials forming the surface treatment were dissolved in a solvent having a boiling point of less than 185° C.

[0230] In one embodiment, the material forming the surface treatment during the formation of the active layer is dissolved in a solvent containing isopropyl alcohol. In one embodiment, the material forming the surface treatment during the formation of the active layer is dissolved in a solvent that is substantially free of n-methyl-2-pyrrolidone. In one embodiment, the material forming the surface treatment during the formation of the active layer is dissolved in a solvent that is substantially free of pyrrolidone compounds.

[0231] In some embodiments, the network is at least 90% carbon by weight. In some embodiments, the network is at least 95% carbon by weight. In some embodiments, the network is at least 99% carbon by weight. In some embodiments, the network is at least 99.9% carbon by weight.

[0232] In some embodiments, the network comprises a network of electrically interconnected carbon elements that exhibits connectivity above the percolation threshold. In some embodiments, the network defines one or more highly electrically conductive pathways. In some embodiments, the pathways have a length greater than 100 μm. In some embodiments, the pathways have a length greater than 1000 μm. In some embodiments, the pathways have a length greater than 10,000 μm.

[0233] In some embodiments, the network contains one or more structures formed from carbon elements, the structures having an overall length at least 10 times the length of the largest dimension of the carbon elements, In some embodiments, the network contains one or more structures formed from carbon elements, the structures having an overall length at least 100 times the length of the largest dimension of the carbon elements.

[0234] In one embodiment, the network contains one or more structures formed of carbon elements, said structures comprising an overall length at least 1000 times the length of the largest dimension of the carbon elements.

[0235] In some embodiments, the surface treatment comprises a surfactant layer disposed on the carbon element, hi some embodiments, the surfactant layer is bonded to the carbon element.

[0236] In some embodiments, the surfactant layer includes a plurality of surfactant elements each having a hydrophobic end and a hydrophilic end, the hydrophobic end disposed proximal to surface one of the carbon element and the hydrophilic end disposed distal to said surface one of the carbon element. In some embodiments, the hydrophilic ends of at least some of the surfactant elements form bonds with the active material particles. In some embodiments, the bonds include ionic bonds. In some embodiments, the bonds include covalent bonds. In some embodiments, the bonds include at least one selected from the group consisting of π-π bonds, hydrogen bonds, and electrostatic bonds.

[0237] In some embodiments, the hydrophilic ends of the surfactant elements have a polarized charge of a first polarity; and the active material particles carry a polarized charge of a second polarity opposite to the first polarity. In some embodiments, the surfactant layer comprises a water-soluble surfactant. In some embodiments, the surfactant layer comprises ions derived from hexadecyltrimethylammonium hexafluorophosphate. In some embodiments, the surfactant layer comprises ions derived from at least one selected from the group consisting of hexadecyltrimethylammonium tetrafluoroborate, N-(cocoalkyl)-N,N,N-trimethylammonium methylsulfate, cocamidopropyl betaine hexadecyltrimethylammonium acetate, and hexadecyltrimethylammonium nitrate.

[0238] In one embodiment, the surfactant layer comprises a layer of surfactant ions formed by dissolving an ionic compound in a solvent.

[0239] In some embodiments, the active layer includes residual counter ions to the surfactant ions formed by dissolving the ionic surfactant compound in a solvent. In some embodiments, the counter ions are selected to be compatible with use in an electrochemical cell. In some embodiments, the counter ions are substantially free of halide groups. In some embodiments, the residual counter ions are substantially free of bromine.

[0240] In some embodiments, the ionic surfactant compound comprises at least one selected from the group consisting of hexadecyltrimethylammonium tetrafluoroborate, hexadecyltrimethylammonium tetrafluoroborate, N-(cocoalkyl)-N,N,N-trimethylammonium methyl sulfate, cocoamidopropyl betaine hexadecyltrimethylammonium acetate, and hexadecyltrimethylammonium nitrate. In some embodiments, the carbon element is functionalized. In some embodiments, the carbon element is functionalized with a surfactant material. In some embodiments, the carbon element is functionalized with a functional group that promotes attachment of active material particles to the network. In some embodiments, the functional group comprises at least one selected from the group consisting of a carboxyl group, a hydroxyl group, an amino group, and a silano group.

[0241] In some embodiments, the functionalized carbon elements are formed from a dried aqueous dispersion comprising nano-form carbon and a surfactant. In some embodiments, the functionalized carbon elements are formed from a freeze-dried aqueous dispersion comprising nano-form carbon and a surfactant. In some embodiments, the aqueous dispersion is substantially free of acid.

[0242] In some embodiments, the surface treatment comprises a thin polymer layer disposed on the carbon element, the polymer layer promoting attachment of the active material to the network. In some embodiments, the thin polymer layer comprises a self-assembled polymer. In some embodiments, the thin polymer layer bonds to the active material via hydrogen bonding. In some embodiments, the thin polymer layer has a maximum thickness in a direction perpendicular to the outer surface of the network of 1 nm or less. In some embodiments, the thin polymer layer has a maximum thickness in a direction perpendicular to the outer surface of the network of 10 nm or less. In some embodiments, the thin polymer layer has a maximum thickness in a direction perpendicular to the outer surface of the network of 50 nm or less.

[0243] In some embodiments, less than 1% by volume of the void space defined by the network is filled with the thin polymer layer. In some embodiments, less than 0.1% by volume of the void space defined by the network is filled with the thin polymer layer. In some embodiments, less than 0.1% by volume of the void space defined by the network is filled with the thin polymer layer. In some embodiments, the surface treatment comprises a layer of carbonaceous material formed from pyrolyzed polymeric material.

[0244] In some embodiments, a layer of carbonaceous material formed from the pyrolyzed polymeric material promotes adhesion of the active material particles to the network. In some embodiments, the active material particles comprise a metal oxide. In some embodiments, the active material particles comprise a lithium metal oxide.

[0245] In one embodiment, the active material is entangled in a network. In one embodiment, the surface treatment promotes adhesion between the active material layer and the current collector layer.

[0246] In some embodiments, the surface treatment contains a functional group bonded to the current collector layer. In some embodiments, the functional group is bonded to the current collector layer by a non-covalent bond. In some embodiments, the functional group is bonded to the current collector layer by at least one bond selected from the group consisting of a π-π bond, a hydrogen bond, and an ionic bond.

[0247] In some embodiments, the current collector comprises a metal foil. In some embodiments, the active material layer has a thickness in a direction perpendicular to the current collector of at least 200 μm. In some embodiments, the active material layer has a thickness in a direction perpendicular to the current collector of at least 300 μm. In some embodiments, the active material layer has a thickness in a direction perpendicular to the current collector of at least 400 μm.

[0248] In one embodiment, the device includes an energy storage cell, the energy storage cell including a first electrode including an active material layer; a second electrode; a permeable separator disposed between the first and second electrodes; and an electrolyte wetting the first and second electrodes. In one embodiment, the method includes dispersing high aspect ratio carbon elements and a surface treatment material in a solvent to form an initial slurry, the dispersing step forming a surface treatment on the high aspect ratio carbon; mixing active material into the initial slurry to form a final slurry; coating the final slurry on a substrate; and drying the final slurry to form an electrode active layer.

[0249] In one embodiment, the high aspect ratio carbon elements include elements each having two major dimensions and one minor dimension, with the ratio of the length of each of the major dimensions to the length of the minor dimension being at least 10 times.

[0250] In some embodiments, high aspect ratio carbon elements include elements each having two long dimensions and one short dimension, where the ratio of the length of each of the long dimensions to the length of the short dimension is at least 100. In some embodiments, high aspect ratio carbon elements include elements each having two long dimensions and one short dimension, where the ratio of the length of each of the long dimensions to the length of the short dimension is at least 1000. In some embodiments, high aspect ratio carbon elements include elements each having two long dimensions and one short dimension, where the ratio of the length of each of the long dimensions to the length of the short dimension is at least 10,0000.

[0251] In some embodiments, the high aspect ratio carbon elements include elements each having one long dimension and two short dimensions, where the ratio of the length of each long dimension to the length of each short dimension is at least 10. In some embodiments, the high aspect ratio carbon elements include elements each having one long dimension and two short dimensions, where the ratio of the length of each long dimension to the length of each short dimension is at least 100. In some embodiments, the high aspect ratio carbon elements include elements each having one long dimension and two short dimensions, where the ratio of the length of each long dimension to the length of each short dimension is at least 1000. In some embodiments, the high aspect ratio carbon elements include elements each having one long dimension and two short dimensions, where the ratio of the length of each long dimension to the length of each short dimension is at least 10000.

[0252] In one embodiment, the high aspect ratio carbon elements include carbon nanotubes or carbon nanotube bundles.

[0253] In some embodiments, the high aspect ratio carbon elements include graphene flakes. In some embodiments, the initial slurry has a solids content in the range of 0.1 to 20.0 wt.%.

[0254] In one embodiment, the final slurry has a solids content in the range of 10.0 to 80% by weight.

[0255] In some embodiments, the solvent has a boiling point less than 202° C. In some embodiments, the solvent has a boiling point less than 185° C. In some embodiments, the solvent has a boiling point less than 125° C. In some embodiments, the solvent has a boiling point of 100° C. or less.

[0256] In some embodiments, the solvent comprises at least one selected from the group consisting of methanol, ethanol, 2-propanol and water. In some embodiments, during the formation of the active layer, the material forming the surface treatment is dissolved in a solvent that is substantially free of pyrrolidone compounds. In some embodiments, the solvent is substantially free of n-methyl-2-pyrrolidone.

[0257] In some embodiments, the surface treatment material comprises a surfactant. In some embodiments, the surfactant is substantially free of halide groups. In some embodiments, the surfactant is substantially free of bromine.

[0258] In some embodiments, forming the surface treatment includes forming a surfactant layer on the carbon element. In some embodiments, the surface treatment is a self-assembled layer. In some embodiments, the surfactant layer includes disposing a plurality of surfactant elements on the surface of the carbon element, each of the surfactant elements having a hydrophobic end and a hydrophilic end, the hydrophobic end disposed proximal to surface one of the carbon element and the hydrophilic end disposed distal to said surface one of the carbon element. In some embodiments, the hydrophobic ends of at least some of the surfactant elements are caused to form bonds with the active material particles. In some embodiments, the bonds include ionic bonds. In some embodiments, the bonds include covalent bonds. In some embodiments, the bonds include at least one selected from the group consisting of π-π bonds, hydrogen bonds, and electrostatic bonds.

[0259] In one embodiment, the hydrophilic ends of the surfactant elements have a polarized charge of a first polarity; and the active material particles carry a polarized charge of a second polarity opposite to the first polarity. In one embodiment, the surfactant material comprises at least one selected from the group consisting of hexadecyltrimethylammonium tetrafluoroborate, hexadecyltrimethylammonium tetrafluoroborate, N-(cocoalkyl)-N,N,N-trimethylammonium methyl sulfate, cocoamidopropyl betaine hexadecyltrimethylammonium acetate, and hexadecyltrimethylammonium nitrate.

[0260] In some embodiments, dispersing the high aspect ratio carbon elements and the surface treatment material in a solvent to form an initial slurry includes applying a force to the aggregated carbon elements to slide the elements away from each other in a direction transverse to the minor axis of the elements. In some embodiments, drying the final slurry at a temperature less than 202° C. In some embodiments, drying the final slurry at a temperature less than 185° C.

[0261] Some embodiments include drying the final slurry at a temperature below 125° C. Some embodiments include drying the final slurry at a temperature below 100° C.

[0262] In some embodiments, the active layer is calendered to promote adhesion between the active material and the network. In some embodiments, the method includes dispersing high aspect ratio carbon elements and a surface treatment material in an aqueous solvent to form an initial slurry, said dispersing step forming a surface treatment on the high aspect ratio carbon; and drying the initial slurry to remove substantially all of the water, resulting in a dry powder of high aspect ratio carbon and the surface treatment thereon.

[0263] In some embodiments, drying the initial slurry comprises freeze-drying the initial slurry. In some embodiments, the aqueous solvent and the initial slurry are substantially free of materials that are damaging to the high aspect ratio carbon elements. In some embodiments, the aqueous solvent and the initial slurry are substantially free of acids. In some embodiments, the initial slurry consists essentially of the high aspect ratio carbon elements, the surface treatment material, and water.

[0264] In one embodiment, the method includes dispersing a dry powder of high aspect ratio carbon with a surface treatment in a solvent and adding an active material to form a second slurry; coating the second slurry on a substrate; and drying the second slurry to form an electrode active layer. In one embodiment, the high aspect ratio carbon elements include elements each having two major dimensions and one minor dimension, the ratio of the length of each of the major dimensions to the length of the minor dimension being at least 10 times.

[0265] In some embodiments, high aspect ratio carbon elements include elements each having two long dimensions and one short dimension, where the ratio of the length of each of the long dimensions to the length of the short dimension is at least 100. In some embodiments, high aspect ratio carbon elements include elements each having two long dimensions and one short dimension, where the ratio of the length of each of the long dimensions to the length of the short dimension is at least 1000. In some embodiments, high aspect ratio carbon elements include elements each having two long dimensions and one short dimension, where the ratio of the length of each of the long dimensions to the length of the short dimension is at least 10,0000.

[0266] In some embodiments, high aspect ratio carbon elements include elements each having one long dimension and two short dimensions, where the ratio of the length of each long dimension to the length of each of the short dimensions is at least 10. In some embodiments, high aspect ratio carbon elements include elements each having one long dimension and two short dimensions, where the ratio of the length of each long dimension to the length of each of the short dimensions is at least 100. In some embodiments, high aspect ratio carbon elements include elements each having one long dimension and two short dimensions, where the ratio of the length of each long dimension to the length of each of the short dimensions is at least 1000.

[0267] In some embodiments, the high aspect ratio carbon elements comprise carbon nanotubes or carbon nanotube bundles. In some embodiments, the high aspect ratio carbon elements comprise graphene flakes. In some embodiments, the solvent has a boiling point less than 202° C. In some embodiments, the solvent has a boiling point less than 185° C. In some embodiments, the solvent has a boiling point less than 125° C. In some embodiments, the solvent has a boiling point equal to or less than 100° C. In some embodiments, the secondary solvent comprises at least one selected from the group consisting of methanol, ethanol, 2-propanol, and water.

[0268] In some embodiments, the second solvent is substantially free of pyrrolidone compounds.

[0269] In some embodiments, the second solvent is substantially free of n-methyl-2-pyrrolidone. In some embodiments, the surface treatment material comprises a surfactant. In some embodiments, the surfactant is substantially free of halide groups. In some embodiments, the surfactant is substantially free of bromine.

[0270] In some embodiments, forming the surface treatment includes forming a surfactant layer on the carbon element. In some embodiments, the surfactant layer is a self-assembled layer. In some embodiments, the second slurry is dried at a temperature less than 202° C.

[0271] In some embodiments, the method includes drying the second slurry at a temperature less than 185° C. In some embodiments, the second slurry is dried at a temperature less than 125° C. In some embodiments, the second slurry is dried at a temperature equal to or less than 100° C. In some embodiments, the active layer is calendered to promote adhesion.

[0272] Any directional terminology shown herein is for introduction purposes only and is not intended to limit the invention. For example, the "top" layer may also be referred to as the second layer and the "bottom" layer may also be referred to as the first layer. Other nomenclature and arrangements may be used without limiting the teachings herein.

[0273] Various other elements may be included and named to provide the gist of the teachings herein For example, additional materials, combinations of materials and / or omissions of materials may be used to provide additional aspects that are within the scope of the teachings herein.

[0274] Various modifications of the teachings herein may be implemented. Generally, the modifications may be designed at the request of a user, designer, manufacturer, or similar party. The modifications may be intended to meet particular standards of performance deemed important by that party. Similarly, suitability of performance may be assessed by the appropriate user, designer, manufacturer, or other similar party.

[0275] Although some chemicals may be listed herein as providing a particular function, a given chemical may serve other purposes.

[0276] When describing elements of the invention or embodiments thereof, the articles "a," "an," and "the" are intended to mean one or more of the element. Similarly, the adjective "another," when used to describe an element, is intended to mean one or more of the element. The terms "including" and "having" are intended to include that there may be additional elements other than the listed elements. As used herein, the term "exemplary" is not intended to imply an exemplary example. Rather, "exemplary" refers to an embodiment that is one of many possible embodiments.

[0277] The entire contents of each of the above-mentioned publications and patent applications are incorporated herein by reference. In the event that any of the referenced documents conflicts with the present disclosure, the present disclosure shall control.

[0278] Any functional language used in the appended claims is not intended to be construed as invoking the interpretation of 35 U.S.C. §112(f) as "means-plus-function" language, unless specifically expressed in an individual claim by use of the words "means for" or "steps for."

[0279] Although the present invention has been disclosed with reference to exemplary embodiments, it will be understood that various changes may be made and equivalents may be substituted for the elements thereof without departing from the scope of the invention. For example, in some embodiments, one of the layers described above may include multiple layers therein. In addition, many modifications to the teachings of the invention will be welcomed to adapt to a particular device, situation or material without departing from the essential scope of the invention. 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 the invention includes all embodiments falling within the scope of the appended claims.

Claims

1. A network of high aspect ratio carbon elements that defines a void space within the network, a plurality of electrode active material particles disposed within the void space of the network and trapped within the network, a surface treatment on the surface of the high aspect ratio carbon element that promotes adhesion between the high aspect ratio carbon element and the active material particles, and an electrode active layer including the same.

2. The device according to claim 1, wherein the high aspect ratio carbon element includes an element having two long dimensions and one short dimension, and the ratio of the length of each long dimension to the length of the short dimension is at least 10 times.

3. The device according to claim 1 or 2, wherein the high aspect ratio carbon element includes an element having two long dimensions and one short dimension, and the ratio of the length of each long dimension to the length of the short dimension is at least 100 times.

4. The device according to claim 1 or 2, wherein the high aspect ratio carbon element includes an element having two long dimensions and one short dimension, and the ratio of the length of each long dimension to the length of the short dimension is at least 1000 times.

5. The device according to claim 1 or 2, wherein the high aspect ratio carbon element includes an element having two long dimensions and one short dimension, and the ratio of the length of each long dimension to the length of the short dimension is at least 100,000 times.

6. The device according to claim 1 or 2, wherein the high aspect ratio carbon element includes an element having one long dimension and two short dimensions, and the ratio of the length of each long dimension to the length of each short dimension is at least 10 times.

7. The device according to claim 1 or 2, wherein the high aspect ratio carbon element includes an element having one long dimension and two short dimensions, and the ratio of the length of each long dimension to the length of each short dimension is at least 100 times.

8. The device according to claim 1 or 2, wherein the high aspect ratio carbon element includes an element having one long dimension and two short dimensions, and the ratio of the length of each long dimension to the length of each short dimension is at least 1000 times.

9. The device according to claim 1 or 2, wherein the high aspect ratio carbon element includes an element having one long dimension and two short dimensions, and the ratio of the length of each long dimension to the length of each short dimension is at least 10,000 times.

10. The device according to claim 1 or 2, wherein the high aspect ratio carbon element includes a carbon nanotube or a carbon nanotube bundle.

11. 3. The device of claim 1 or 2, wherein the high aspect ratio carbon elements comprise graphene flakes.

12. 3. The device of claim 1 or 2, wherein the electrode active layer contains less than 10% by weight of a polymer binder disposed in the void spaces.

13. 3. The device of claim 1 or 2, wherein the electrode active layer contains less than 1% by weight of a polymer binder disposed in the void spaces.

14. 3. The device of claim 1 or 2, wherein the electrode active layer contains less than 1% by weight of a polymer binder disposed in the void spaces.

15. 3. The device of claim 1 or 2, wherein the electrode active layer is substantially free of polymeric materials other than the surface treatment.

16. 3. The device of claim 1 or 2, wherein the electrode active layer is substantially free of polymeric materials.

17. 3. The device of claim 1 or 2, wherein the surface treatment comprises a material that is soluble in a solvent having a boiling point below 202°C.

18. 3. The device of claim 1 or 2, wherein the surface treatment comprises a material that is soluble in a solvent having a boiling point below 185°C.

19. 3. The device according to claim 1 or 2, wherein during the formation of the active layer, the material forming the surface treatment is dissolved in a solvent having a boiling point below 202°C.

20. 3. The device according to claim 1 or 2, wherein during the formation of the active layer, the material forming the surface treatment is dissolved in a solvent having a boiling point below 185°C.

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