Electrode for an energy storage device

Abstract

Disclosed herein is an apparatus comprising an electrode active layer comprising: a network of high aspect ratio carbon elements defining interstitial spaces within the network; a plurality of electrode active material particles disposed in the interstitial spaces within the network and entangled in the network; and a surface treatment on surfaces of the high aspect ratio carbon elements that promotes adhesion between the high aspect ratio carbon elements and the active material particles.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 596,694, filed November 7, 2023, which is incorporated herein by reference in its entirety. Background Technology

[0003] Lithium-ion batteries are used in many products, including medical devices, electric vehicles, aircraft, and consumer products such as laptops, 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 find new applications in products and emerging industries.

[0004] Typically, a lithium-ion battery (“LIB” or “LiB”) comprises an anode, a cathode, and an electrolyte material, such as an organic solvent containing lithium salts. More specifically, the anode and cathode (collectively referred to as “electrodes”) are formed by mixing the anode or cathode active material with a binder and solvent to form a paste or slurry, then coating the paste or slurry onto a current collector (such as aluminum or copper) and drying it, thereby forming a thin film on the current collector. The anode and cathode are then layered or coiled before being housed in a pressurized casing containing the electrolyte material, all of which together form the lithium-ion battery.

[0005] In conventional electrodes, adhesives with sufficient adhesive and chemical properties are used to ensure that the film coated on the current collector remains in contact with it even when manipulated to fit a pressurized battery casing. Since the film contains the electrode active material, insufficient contact between the film and the current collector can significantly interfere with the battery's electrochemical characteristics. Furthermore, it is important to select an adhesive that is mechanically compatible with the electrode active material, enabling it to withstand the expansion and contraction of the active material during battery charging and discharging.

[0006] Therefore, adhesives such as cellulose binders or cross-linked polymer binders have been used to provide good mechanical properties. However, such adhesive materials have adverse effects. For example, the bulk of the adhesive fills the volume in the electrode active layer, which can further increase the mass loading of the active material and reduce the conductivity of the electrode. In addition, the adhesive tends to react electrochemically with the electrolyte used in the battery cell (especially in high-voltage, high-current and / or high-temperature applications), leading to a degradation in the battery cell performance. Summary of the Invention

[0007] The applicant has recognized that electrodes can be constructed to exhibit excellent mechanical stability without the need for a bulk polymer binder. In one aspect, this disclosure describes an embodiment of an electrode active layer comprising a network of high aspect ratio carbon elements (e.g., carbon nanotubes, carbon nanotube bundles, graphene sheets, etc.) providing a highly conductive scaffold, which entangles or wraps around the active material, thereby supporting the layer. As detailed below, surface treatments can be applied to the high aspect ratio carbon elements to promote their adhesion to the active material and any underlying electrode layer (e.g., current collector layer), thereby improving the overall cohesion and mechanical stability of the active layer. This surface treatment forms only a thin (in some cases even monomolecular) layer on the network, leaving large void spaces without any bulk binder material and thus instead capable of being filled with the active material. The resulting active layer can be formed with excellent mechanical stability, even under large thicknesses and high active material mass loads.

[0008] In another aspect, this disclosure describes a method comprising: dispersing high aspect ratio carbon elements and a surface treatment material in a solvent to form an initial slurry, wherein the dispersion step causes a surface treatment to be formed on the high aspect ratio carbon; mixing an active material into the first slurry to form a final slurry; coating the final slurry onto a substrate; and drying the final slurry to form an electrode active layer.

[0009] Various implementations may include any feature or element described herein individually or any suitable combination of any feature or element described herein. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of an electrode characterized by an active material layer.

[0011] Figure 2 This is a detailed illustration of the implementation scheme for the active material layer.

[0012] Figure 3 This is a detailed illustration of the active material layer in another implementation scheme.

[0013] Figure 4 These are electron micrographs of the type of active material described in this article.

[0014] Figure 5 This is a schematic diagram of an energy storage battery unit.

[0015] Figure 6 This shows the preparation Figure 1 The flowchart shows the method for using electrodes.

[0016] Figure 7 A schematic diagram of a pouch cell battery is shown.

[0017] Figure 8 A summary of the functional parameters of the pouch cell battery for EV applications is shown.

[0018] Figure 9 A summary of the functional parameters of the pouch cell battery is shown.

[0019] Figure 10 The results of a comparative performance evaluation of a pouch cell featuring a binder-free cathode (left figure) and a pouch cell featuring a binder-based cathode (right figure) are shown.

[0020] Figure 11 The results of a comparative performance evaluation of a pouch cell featuring a binder-free cathode (upper trace) and a pouch cell featuring a binder-based cathode (lower trace) are shown.

[0021] Figure 12 This is a schematic diagram of a half-cell lithium battery device.

[0022] Figure 13 This is a graph showing the potential (with Li / Li+ potential as a reference) of a binder-free cathode half-cell (solid trace) and a reference binder-based cathode half-cell (dashed trace) at various current densities, relative to specific capacity.

[0023] Figure 14 This is a graph showing the potential (with Li / Li+ potential as a reference) of a binder-free cathode half-cell (solid trace) and a reference binder-based cathode half-cell (dashed trace) at various current densities, relative to the volumetric capacity.

[0024] Figure 15 A graph showing the volumetric capacity versus current density of a binder-free cathode half-cell (upper trace) and a reference binder-based cathode half-cell (lower trace) is presented.

[0025] Figure 16 The Nyquist plots of electrochemical impedance spectroscopy for several binder-free cathode half-cell units (traces marked with squares, circles, and triangles) and a reference binder-based cathode half-cell unit are shown. The binder-free cathode half-cell units exhibit significantly better performance than the reference cell unit. Detailed Implementation

[0026] refer to Figure 1The image shows an electrode 10, which includes an active layer 100 disposed on a current collector 101. Some embodiments may include an optional adhesive layer 102 disposed between the active layer 100 and the current collector 101. In other embodiments, the adhesive layer 102 may be omitted.

[0027] Current collector 101 may be a conductive layer, such as a metal foil. Optional adhesive layer 102 (which may be omitted in some embodiments) may be a material layer that promotes adhesion between current collector 101 and active layer 100. Examples of materials suitable for current collector 101 and optional adhesive layer 102 are described in International Patent Publication No. WO / 2018 / 102652, published on 7 June 2018.

[0028] Electrode active layer

[0029] exist Figure 2 In some embodiments depicted, the active layer 100 may include a three-dimensional network 200 of high aspect ratio carbon elements 201, which define void spaces within the network 200. A plurality of active material particles 300 are disposed within the void spaces of the network 200. Therefore, the active material particles are entangled or bound together in the network 200, thereby increasing the cohesion of the active layer 100.

[0030] In some embodiments, a surface treatment 202 (not shown, see reference) is applied to the surface of the high aspect ratio carbon element 201 of the network 200. Figure 2 Surface treatment promotes adhesion between high aspect ratio carbon elements and active material particles 300. Surface treatment can also promote adhesion between high aspect ratio carbon elements and current collector 101 (also referred to herein as the “conductive layer”) and / or optional adhesion layer 102.

[0031] As used herein, the term "high aspect ratio carbon element" refers to a carbonaceous element that has a size in one or more dimensions ("major dimensions") that is significantly larger than the size of the element in the lateral dimension ("minor dimensions").

[0032] For example, in some embodiments, the high aspect ratio carbon element 201 may comprise an element having a sheet or plate shape having two primary dimensions and one secondary dimension. For example, in some such embodiments, the length ratio of each primary dimension may be at least 5, 10, 100, 500, 1,000, 5,000, 10,000, or more times the length ratio of the secondary dimension. Exemplary elements of this type include graphene sheets or flakes.

[0033] For example, in some embodiments, the high aspect ratio carbon element 201 may comprise an element having an elongated rod or fiber shape having one primary dimension and two secondary dimensions. For example, in some such embodiments, the length ratio of the primary dimension may be at least 5, 10, 100, 500, 1,000, 5,000, 10,000, or more times the length ratio of each of the secondary dimensions. Exemplary elements of this type include carbon nanotubes, carbon nanotube bundles, carbon nanorods, and carbon fibers.

[0034] In some embodiments, the high aspect ratio carbon element 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 element 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 element 201 may include graphene in the form of sheets, flakes, or bent flakes and / or formed as high aspect ratio cones, rods, etc.

[0035] In some embodiments, the electrode active layer 100 may contain very little or no bulk binder material, thereby leaving more space in the network 200 for the active material particles 300 to occupy. For example, in some embodiments, the active layer 200 contains less than 10% by weight, less than 1% by weight, less than 0.1% by weight, less than 0.01% by weight, or less binder material (e.g., polymeric or cellulose binder material) disposed in the void spaces.

[0036] For example, in some embodiments, the electrode active layer contains no or substantially no polymer material or any material other than the active material 300, and the network 200 is composed of high aspect ratio carbon elements 201 and a surface treatment 202 disposed on the high aspect ratio carbon elements.

[0037] In some implementations, network 200 is composed mostly or even entirely of carbon. For example, in some implementations, network 200 is at least 90% by weight of carbon, at least 95% by weight of carbon, at least 96% by weight of carbon, at least 97% by weight of carbon, at least 98% by weight of carbon, at least 99% by weight of carbon, at least 99.5% by weight of carbon, at least 99.9% by weight of carbon, or more of carbon.

[0038] In some embodiments, the size of the high aspect ratio carbon elements 201 forming the network 200 along one or two principal dimensions (e.g., average size, median size, or minimum size) 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 larger. For example, in some embodiments, the size of the elements 201 forming the network 200 (e.g., average size, median size, or minimum size) can be in the range of 1 μm to 1000 μm or any subrange thereof, such as within 1 μm to 600 μm.

[0039] In some implementations, the size of the elements can be relatively uniform. For example, in some implementations, more than 50%, 60%, 70%, 80%, 90%, 95%, 99% or more of the elements 201 can have a size within 10% of the average size of the elements 201 constituting the network 200 along one or two major dimensions.

[0040] The applicant has discovered that the active layer 100 of this type can provide exemplary properties (e.g., high conductivity, low resistance, high voltage performance, and high energy density and high power density) even when the mass fraction of the high aspect ratio carbon element 201 constituting the network 200 in the layer 100 is relatively low, thereby allowing the active material particles 300 to have a high mass loading. For example, in some embodiments, the active layer 100 may be at least about 50 wt%, 60 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, 99.5 wt% or more of active material particles 300.

[0041] In some embodiments, network 200 forms an interconnect network for highly conductive paths of current flow (e.g., electron or ion transport) through active layer 100. For example, in some embodiments, highly conductive junctions may appear at points where elements 201 of the network intersect each other or are close enough to allow charge carriers (e.g., electrons or ions) to quantum tunnel from one element to the next. While elements 201 may constitute a relatively low mass fraction 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 in any of its subranges, such as 1 wt% to 5.0 wt%), the interconnect network of highly conductive paths formed in network 200 can provide long conductive paths (e.g., conductive paths approximately the thickness of active layer 100) to facilitate current flow within and through active layer 100.

[0042] For example, in some embodiments, network 200 may include one or more structures of interconnect elements 201, wherein the one or more structures have a total length along one or more dimensions that is 2, 3, 4, 5, 10, 20, 50, 100, 500, 1,000, 10,000, or more times the average length of the component elements 201 constituting the structure. For example, in some embodiments, network 200 may include one or more structures of interconnect elements 200, wherein the one or more structures have a total length in the range of 2 to 10,000 times (or any subrange thereof) the average length of the component elements 201 constituting the structure. For example, in some embodiments, network 200 may include highly conductive paths having a length greater than 100 μm, 500 μm, 1,000 μm, 10,000 μm, or longer, for example, in the range of 100 μm to 10,000 μm in any subrange thereof.

[0043] As used herein, the term “high conductivity path” should be understood as a path formed by interconnecting elements 201 that has a conductivity higher than that of active material particles entangled in network 200.

[0044] To avoid being bound by theory, in some implementations, network 200 may be characterized by exhibiting an electrical interconnection network of elements 201 with connectivity above a percolation threshold. The percolation threshold is a mathematical concept related to percolation theory, which describes the formation of long-range connectivity in stochastic systems. Below the threshold, there are no so-called "giant" connected branches approximately the size of the system; above the threshold, giant branches approximately the size of the system exist.

[0045] In some embodiments, the percolation threshold can be determined by increasing the mass fraction of element 201 in the layer while simultaneously measuring the conductivity of the active layer 100, thereby keeping all other properties of the layer constant. In some such cases, the threshold can be identified by adding more element 201 when the mass fraction of the layer's conductivity increases sharply and / or is higher than the mass fraction where the layer's conductivity increases only slowly with increasing conductivity. This behavior indicates that the threshold required to form an interconnect structure providing a conductive path with a length approximately the size of the active layer 100 has been crossed.

[0046] Figure 2 Network 200 (e.g.) is shown Figure 1A detailed view of a high aspect ratio carbon element 201 located near several active material particles 300 (shown). In the illustrated embodiment, the surface treatment 202 on element 201 is a surfactant layer bonded to the outer layer of the surface of element 201. As shown, the surfactant layer comprises a plurality of surfactant elements 210, each surfactant element having a hydrophobic end 211 and a hydrophilic end 212, wherein the hydrophobic end is disposed proximal to the surface of carbon element 201, and the hydrophilic end 212 is disposed distal to the surface.

[0047] In some embodiments where carbon element 201 is hydrophobic (as is typically the case with carbon elements in nanoforms, such as CNTs, CNT bundles, and graphene sheets), the hydrophobic end 211 of surfactant element 210 will be attracted to carbon element 201. Therefore, in some embodiments, surface treatment 202 can be a self-assembled layer. For example, as detailed below, in some embodiments, when element 201 and surfactant element 210 are mixed in a solvent to form a slurry, the surface treatment 202 layer will self-assemble on the surface due to the electrostatic interactions between elements 201 and 210 within the slurry.

[0048] In some embodiments, surface treatment 202 may be a self-confining layer. For example, as detailed 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 within the slurry. In some such embodiments, once a surface region of element 201 is covered by surfactant element 210, additional surfactant element 210 will not be attracted to said region. In some embodiments, once the surface of element 201 is covered by surfactant element 202, additional elements are repelled away from the layer, thus forming a self-confining process. For example, in some embodiments, surface treatment 202 may be formed during a self-confining process, thereby ensuring that the layer will be thin, for example, as thick as a single molecule or a few molecules.

[0049] In some embodiments, at least a portion of the hydrophilic end 212 of the surfactant element forms a bond with the active material particle 300. Therefore, surface treatment 202 can provide good adhesion between the elements 201 of the network 200 and the active material particles. In some embodiments, the bond can be a covalent bond or a non-covalent bond, such as a π-π bond, a hydrogen bond, an electrostatic bond, or a combination thereof.

[0050] For example, in some embodiments, the hydrophilic end 212 of the surfactant element 210 has a first polar charge; while the surface of the active material particles 300 has a second polar charge, which is opposite to the first polarity, and thus they are attracted to each other.

[0051] For example, in some embodiments where the active material particles 300 and the carbon elements 201 carrying the surface treatment 202 are combined in a solvent during the formation of layer 100 (as described in more detail below), the outer surface of the active material particles 300 may be characterized by having a zeta potential (as is known in the art) with an opposite sign to that of the zeta potential of the outer surface of the surface treatment 202. Therefore, in some such embodiments, the attractive force between the carbon elements 201 carrying the surface treatment 202 and the active material product 300 promotes the self-assembly of a structure in which the active material particles 300 and the carbon elements 201 of the network 200 are entangled.

[0052] In some embodiments, at least a portion of the hydrophilic end 212 of the surfactant element forms a bond with the current collector layer or adhesion layer beneath the active material layer 100. Therefore, surface treatment 202 can provide good adhesion between the elements 201 of the network 200 and such underlying layers. In some embodiments, the bond can be a covalent or non-covalent bond, such as a π-π bond, hydrogen bond, electrostatic bond, or a combination thereof. In some embodiments, this arrangement provides excellent mechanical stability for the electrode 10, as discussed in more detail below.

[0053] In various embodiments, the surfactant used to form the surface treatment 202 described above may comprise any suitable material. For example, in some embodiments, the surfactant may comprise one or more of the following: hexadecyltrimethylammonium hexafluorophosphate (CTAP), hexadecyltrimethylammonium tetrafluoroborate (CTAB), hexadecyltrimethylammonium acetate, hexadecyltrimethylammonium nitrate, cocamidopropyl betaine, N-(cocarbamoyl)-N,N,N-trimethylammonium methyl sulfate, and cocamidopropyl betaine. Additional suitable materials are described below.

[0054] In some embodiments, the surfactant layer 202 can be formed by dissolving a compound in a solvent, such that ions from the compound form a layer of surfactant (e.g., a self-limiting process as described above). In some such embodiments, the active layer 100 then includes residual counterions 214 comprising the surfactant ions that formed the surface treatment 202.

[0055] In some embodiments, these surfactant counterions 214 are selected to be compatible with the use of the electrochemical battery cell. For example, in some embodiments, counterions that are non-reactive or only slightly reactive with the materials used in the battery cell, such as the electrolyte, separator, and casing, are selected. For example, if an aluminum casing is used, counterions that are non-reactive or only slightly reactive with the aluminum casing can be selected.

[0056] For example, in some embodiments, the residual counter ion contains no or substantially no halide groups. For example, in some embodiments, the residual counter ion contains no or substantially no bromine.

[0057] In some embodiments, residual counterions compatible with the electrolyte used in the energy storage battery cell containing the active layer 200 can be selected. For example, in some embodiments, the residual counterions may be the same ionic species used in the electrolyte itself. For example, if the electrolyte comprises a dissolved Li PF6 salt, the electrolyte anion is PF6. In this case, a surfactant such as CTA PF6 can be selected, such that the surface treatment 202 forms an anionic layer from CTA PF6, and the residual surfactant counterions are PF6 anions from CTA PF6 (thus matching the anions of the electrolyte).

[0058] In some embodiments, the surfactant material used is soluble in a solvent that exhibits advantageous properties. For example, in some embodiments, the solvent may include water or an alcohol, such as methanol, ethanol, or 2-propanol (isopropanol, sometimes referred to as IPA), or combinations thereof. In some embodiments, the solvent may include one or more additives for further improving the properties of the solvent, such as low-boiling-point additives, such as acetonitrile (ACN), deionized water, and tetrahydrofuran.

[0059] For example, if a low-boiling-point solvent is used in the formation of surface treatment 202, the solvent can be quickly removed using a thermal drying process performed at a relatively low temperature (e.g., a thermal drying process of the type described in more detail below). As those skilled in the art will understand, this can improve the manufacturing speed and / or cost of the active layer 202.

[0060] For example, in some embodiments, the surface treatment 202 is formed of a material that is soluble in a solvent having a boiling point of less than 250°C, 225°C, 202°C, 200°C, 185°C, 180°C, 175°C, 150°C, 125°C or lower, for example, less than or equal to 100°C.

[0061] In some embodiments, the solvent may exhibit other advantageous properties. In some embodiments, the solvent may have a low viscosity, such as less than or equal to 3.0 centipoise, 2.5 centipoise, 2.0 centipoise, 1.5 centipoise, or lower at 20°C. In some embodiments, the solvent may have a low surface tension, such as less than or equal to 40 mN / m, 35 mN / m, 30 mN / m, 25 mN / m, or lower at 20°C. In some embodiments, the solvent may have low toxicity, for example, comparable to that of alcohols such as isopropanol.

[0062] It is noteworthy that this contrasts with the process used to form conventional electrode active layers, which are characterized by bulk binder materials such as polyvinylidene fluoride (PVDF) or polyvinylidene fluoride (PVDF). Such bulk binders require aggressive solvents, typically 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 a high-temperature drying process to remove the solvent. Furthermore, NMP is expensive, requires complex solvent recovery systems, and is highly toxic, posing serious safety concerns. In contrast, as further detailed below, in various embodiments, the active layer 200 can be formed without the use of NMP or similar compounds such as pyrrolidone compounds.

[0063] While an exemplary surface treatment 202 of one type has been described above, it should be understood that other treatments may also be used. For example, in various embodiments, surface treatment 202 may be formed by functionalizing a high aspect ratio carbon element 201 using any suitable technique described herein or known in the art. The functional groups applied to element 201 may be selected to promote adhesion between the active material particles 300 and the network 200. For example, in various embodiments, the functional groups may include carboxyl, hydroxyl, amino, silyl, or combinations thereof.

[0064] As will be described in more detail below, in some embodiments, the functionalized carbon element 201 is formed from a dried (e.g., lyophilized) aqueous dispersion comprising nanoform carbon and functionalizing materials such as surfactants. In some such embodiments, the aqueous dispersion is substantially free of materials that would damage the carbon element 201, such as acids.

[0065] refer to Figure 3 In some embodiments, the surface treatment 202 of the high aspect ratio carbon element 201 includes a thin polymer layer disposed on the carbon element, said thin polymer layer promoting adhesion of the active material to the network. In some such embodiments, the thin polymer layer comprises a self-assembled polymer layer and / or a self-confining polymer layer. In some embodiments, the thin polymer layer is bonded to the active material, for example, through hydrogen bonding.

[0066] In some embodiments, the thin polymer layer may have a thickness of less than 3 times, 2 times, 1 time, 0.5 times, 0.1 times (or less) the secondary size of element 201 in the direction normal to the outer surface of the carbon element.

[0067] In some embodiments, the thin polymer layer includes functional groups (e.g., side functional groups) bonded to the active material, for example, by non-covalent bonding such as π-π bonding. In some such embodiments, the thin polymer layer may form a stable capping layer over at least a portion of element 201.

[0068] In some embodiments, a thin polymer layer on some elements of element 201 may be bonded to the current collector 101 or the adhesion layer 102 beneath the active layer 200. For example, in some embodiments, the thin polymer layer includes surface bonds to the current collector 101 or the adhesion layer 102, for example, through non-covalent bonding, such as π-π bonded side functional groups. In some such embodiments, the thin polymer layer may form a stable capping layer over at least a portion of element 201. In some embodiments, this arrangement provides superior mechanical stability to the electrode 10, as discussed in more detail below.

[0069] In some embodiments, the polymeric material is miscible in solvents of the types described in the examples above. For example, in some embodiments, the polymeric material is miscible in solvents including alcohols such as methanol, ethanol, or 2-propanol (isopropanol, sometimes referred to as IPA) or combinations thereof. In some embodiments, the solvent may include one or more additives for further improving the properties of the solvent, such as low-boiling-point additives such as acetonitrile (ACN), deionized water, and tetrahydrofuran.

[0070] Suitable examples of materials that can be used to form polymer layers include water-soluble polymers such as polyvinylpyrrolidone. Additional exemplary materials are provided below.

[0071] In some embodiments, the polymer material has a low molecular weight, for example, less than or equal 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.

[0072] Note that the thin polymer layer described above differs in quality from the bulk polymer binder used in conventional electrodes. Instead of filling a large portion of the volume of the active layer 100, the thin polymer layer resides on the surface of the high aspect ratio carbon elements, thereby leaving voids within the network 200 that can be used to retain the vast majority of the active material particles 300.

[0073] For example, in some embodiments, the thin polymer layer has a maximum thickness of less than or equal to 1, 0.5, 0.25, or less than the size of the carbon element 201 along its secondary dimension in a direction normal to the outer surface of the network. For example, in some embodiments, the thin polymer layer may be only a few molecules thick (e.g., less than or equal to 100, 50, 10, 5, 4, 3, 2, or even 1 molecule thick). 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 by the thin polymer layer.

[0074] In yet another exemplary embodiment, surface treatment 202 may form a carbonaceous material layer produced by the pyrolysis of a polymeric material disposed on high aspect ratio carbon elements 201. This carbonaceous material (e.g., graphite or amorphous carbon) layer may adhere (e.g., via covalent bonds) to or otherwise facilitate adhesion to the active material particles 300. Examples of suitable pyrolysis techniques are described in U.S. Patent Application Serial No. 63 / 028982, filed May 22, 2020. A suitable polymeric material for this technique is polyacrylonitrile (PAN).

[0075] In various embodiments, the active material particles 300 may include any active material suitable for energy storage devices, including metal oxides such as lithium metal oxide.

[0076] For example, the active material particles 300 may include lithium cobalt oxide (LCO, sometimes referred to as "lithium cobaltate / lithium cobaltite"), a chemical compound in which a possible formulation is a variant of LiCoO2; lithium nickel manganese cobalt oxide (NMC, a variant of which has the chemical formula LiNiMnCo); lithium manganese oxide (LMO, a variant of which has the chemical formula LiMn2O4, Li2MnO3, etc.); lithium nickel cobalt aluminum oxide (LiNiCoAlO2 and its variants, such as NCA); and lithium titanate oxide (LTO, a variant of which has the chemical formula Li4Ti5O). 12 ); lithium iron phosphate oxide (LFP, one variant of which has the chemical formula LiFePO4); lithium nickel cobalt aluminum oxide (and its variants, such as NCA); and other similar materials. Other variants of the foregoing may also be included.

[0077] In some embodiments, nickel-rich NMC can be used when NMC is used as the active material. For example, in some embodiments, a variant of NMC may be LiNi. x Mn y Co 1-x-y, where x is equal to or greater than about 0.7, 0.75, 0.80, 0.85 or greater. In some embodiments, so-called NMC811 may be used, where in the aforementioned chemical formula, x is about 0.8 and y is about 0.1.

[0078] In some implementations, the active material includes other forms of lithium nickel manganese cobalt oxide (LiNi). x Mn y Co z O2). For example, common variants can be used, such as, but not limited to: NMC 111 (LiNi). 0.33 Mn 0.33 Co 0.33 O2); NMC 532 (LiNi) 0.5 Mn 0.3 Co 0.2 O2); NMC 622 (LiNi) 0.6 Mn 0.2 Co 0.2 O2); and others.

[0079] In some embodiments, for example when the electrode is used as an anode, the active material may include graphite, hard carbon, activated carbon, nano-carbon, silicon, silicon oxide, or carbon-encapsulated silicon nanoparticles. In some such embodiments, the active layer 100 may be lithium-intercalated, for example using pre-lithiation methods known in the art.

[0080] In some embodiments, the techniques described herein can allow the active layer 100 to be made substantially of materials from the active layer, for example, greater than 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, 99 wt%, 99.5 wt%, 99.8 wt%, or greater, while still 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 can have such a large amount of active material and a large thickness (e.g., greater than 50 µm, 100 µm, 150 µm, 200 µm, or greater) while still exhibiting excellent mechanical properties (e.g., no delamination during operation in an energy storage device of the type described herein).

[0081] The active material particles 201 in the active layer 100 are characterized by an average particle size set in, for example, a range of 0.1 µm to 50 µm or any subrange thereof. The active material particles 201 in the active layer 100 are also characterized by a particle size distribution, which is a unimodal, bimodal, or multimodal particle size distribution. The active material particles 201 may have a size distribution of 0.1 m² / g (m³ / g). 2 / g) and 100 square meters / gram (m 2Specific surface area within the range of / g or any subrange thereof.

[0082] In some embodiments, the active layer 100 may have, for example, at least 20 mg / cm³. 2 30mg / cm 2 40mg / cm 2 50mg / cm 2 60mg / cm 2 70mg / cm 2 80mg / cm 2 90mg / cm 2 100mg / cm 2 The active material particles have a mass loading of 300.

[0083] refer to Figure 4 An electron micrograph of an exemplary active material layer of the type described herein is shown. The tendril-like high aspect ratio carbon elements 201 (formed from CNT bundles) are clearly shown entangled with active material particles 300. Note that there are no bulk polymer materials occupying space within the layer.

[0084] Energy storage battery unit

[0085] refer to Figure 5 The diagram illustrates an energy storage battery cell 500, which includes a first electrode 501, a second electrode 502, a permeable membrane 503 disposed between the first electrode 501 and the second electrode 502, and an electrolyte 504 that wets the first and second electrodes. One or both of electrodes 501 and 502 may be of the type described herein.

[0086] In some embodiments, the energy storage battery cell 500 may be a battery, such as a lithium-ion battery. In some such embodiments, the electrolyte may be a lithium salt dissolved in a solvent, for example, a dielectric of the type described in: QiLi, Juner Chen, Lei Fan, Xueqian Kong, Yingying Lu, Progress in electrolytes for rechargeable Li-based batteries and beyond, Green Energy & Environment, Vol. 1, No. 1, pp. 18-42, the entire contents of which are incorporated herein by reference.

[0087] In some such implementations, the energy storage battery cell may have an operating voltage in the range of 1.0V to 5.0V or any subrange thereof, such as 2.3V to 4.3V.

[0088] In some such implementations, the energy storage battery cell 500 may have an operating temperature range including -40°C to 100°C or any subrange thereof, such as -10°C to 60°C.

[0089] In some such implementations, the energy storage battery cell 500 may have a gravimetric energy density of at least 100Wh / kg, 200Wh / kg, 300Wh / kg, 400Wh / kg, 500Wh / kg, 1000Wh / kg or higher.

[0090] In some such implementations, the energy storage battery cell 500 may have a volumetric energy density of at least 200 Wh / L, 400 Wh / L, 600 Wh / L, 800 Wh / L, 1,000 Wh / L, 1,500 Wh / L, 2,000 Wh / L or higher.

[0091] In some such implementations, the energy storage battery cell 500 may have a C-rate in the range of 0.1 to 50.

[0092] In some such implementations, the energy storage battery cell 500 may have a cycle life of at least 1,000, 1,500, 2,000, 2,500, 3,000, 3,500, 4,000 or more charge-discharge cycles.

[0093] In some embodiments, the energy storage battery cell 500 may be a lithium-ion capacitor of the type described in U.S. Patent Application Serial No. 63 / 021492, filed May 8, 2020, the entire contents of which are incorporated herein by reference.

[0094] In some such implementations, the energy storage battery cell 500 may have an operating temperature range including -60°C to 100°C or any subrange thereof, such as -40°C to 85°C.

[0095] In some such implementations, the energy storage battery cell 500 may have a weight energy density of at least 10Wh / kg, 15Wh / kg, 20Wh / kg, 30Wh / kg, 40Wh / kg, 50Wh / kg or higher.

[0096] In some such implementations, the energy storage battery cell 500 may have a volumetric energy density of at least 20Wh / L, 30Wh / L, 40Wh / L, 50Wh / L, 60Wh / L, 70Wh / L, 80Wh / L or higher.

[0097] In some such implementations, the energy storage battery cell 500 may have a weight power density of at least 5 kW / kg, 7.5 W / kg, 10 kW / kg, 12.5 kW / kg, 14 kW / kg, 15 kW / kg or higher.

[0098] In some such implementations, the energy storage battery 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 higher.

[0099] In some such implementations, the energy storage battery cell 500 may have a C-rate in the range of 1.0 to 100.

[0100] In some such implementations, the energy storage battery cell 500 may have a cycle life of at least 100,000, 500,000, 1,000,000 or more charge-discharge cycles.

[0101] Manufacturing method

[0102] The electrode 10, characterized by the active layer 100, as described herein can be manufactured using any suitable manufacturing process. As those skilled in the art will understand, in some embodiments, the electrode 10 can be manufactured using a wet coating technique of the type described in International Patent Publication No. WO / 2018 / 102652, published on June 7, 2018, with further consideration of the teachings herein.

[0103] refer to Figure 6 In some embodiments, the active layer 100 of electrode 10 can be formed using method 1000. In step 1001, high aspect ratio carbon element 201 and surface treatment material (e.g., surfactant or polymer material as described herein) are combined with a solvent (solvent of the type described herein) to form an initial slurry.

[0104] In step 1002, the initial slurry is treated to ensure good dispersion of the solid material within it. In some embodiments, this treatment includes introducing mechanical energy into the mixture of solvent and solid material (e.g., using an ultrasonic instrument, sometimes also referred to as an "ultrasonic disruptor") 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 higher. For example, the mechanical energy introduced per kilogram of mixture into the mixture can be in the range of 0.4 kWh / kg to 1.0 kWh / kg or any subrange thereof, such as 0.4 kWh / kg to 0.6 kWh / kg.

[0105] In some implementations, an ultrasonic bath mixer may be used. In other implementations, a probe sonicator may be used. For nanoparticle applications, probe sonication can be significantly more powerful and efficient compared to an ultrasonic bath. The high shear forces generated by ultrasonic cavitation can be used to break down particle agglomerates and produce smaller and more uniform particle sizes. Among other things, sonication can produce a stable and homogeneous suspension of solids in a slurry. Typically, this results in solid dispersion, as well as deagglomeration and other decomposition. Examples of probe sonication apparatus include the Q-series probe sonicators available from QSonica LLC, Newtown, Connecticut. Another example includes the Branson Digital SFX-450 sonicator available from Thomas Scientific, Swedesboro, New Jersey.

[0106] However, in some implementations, the localized nature of each probe within the probe assembly can lead to uneven mixing and suspension. This may be the case, for example, with large samples. This can be addressed by using a setup with a continuous flow cell and proper mixing. That is, in such a setup, the slurry will achieve a fairly uniform dispersion.

[0107] In some embodiments, the initial slurry, after processing, will have a viscosity in the range of 5,000 cps to 25,000 cps or any subrange thereof, such as 6,000 cps to 19,000 cps.

[0108] In step 1003, surface treatment 202 may be formed entirely or partially on the high aspect ratio carbon element 201 as an initial slurry. In some embodiments, at this stage, surface treatment 202 may be as described above. Figure 2 and 3 Detailed description of self-assembly. The resulting surface treatment 201 may include functional groups or other features, as described in the additional steps below, which may promote adhesion between the high aspect ratio carbon element 201 and the active material particles 300.

[0109] In step 1004, the active material particles 300 may be combined with the initial slurry to form a final slurry containing the active material particles 300 and high aspect ratio carbon elements 201 on which a surface treatment 202 is formed.

[0110] In some embodiments, the active material 300 can be added directly to the initial slurry. In other embodiments, the active material 300 can first be dispersed in a solvent (e.g., using the techniques described above relative to the initial solvent) to form an active material slurry. This active material slurry can then be combined with the initial slurry to form the final slurry.

[0111] In step 1005, the final slurry is treated to ensure that the solid material is well dispersed in the final slurry. In various embodiments, any suitable mixing process known in the art can be used. In some embodiments, this treatment can use the techniques described above with respect to step 1002. In some embodiments, a planetary mixer, such as a multi-axis (e.g., three-axis or more-axis) planetary mixer, can be used. In some such embodiments, the planetary mixer may have multiple blades, such as two or more mixing blades, and one or more (e.g., two, three, or more) dispersing blades, such as disc dispersing blades.

[0112] In some embodiments, during this step 1005, the matrix 200 to which the active material 300 is entangled can be fully or partially self-assembled, as referenced above. Figure 2 and 3 Detailed description. In some embodiments, the interaction between surface treatment 202 and active material 300 promotes the self-assembly process.

[0113] In some implementations, the final slurry, after processing, will have a viscosity in the range of 1,000 cps to 10,000 cps or any subrange thereof, such as 2,500 cps to 6,000 cps.

[0114] In step 1006, the active layer 100 is formed from the final slurry. In some embodiments, the final slurry can be directly wet-cast onto the current collector conductive layer 101 (or optionally the adhesion layer 102) and allowed to dry. As an example, casting can be performed by applying at least one of heat and vacuum until substantially all solvent and any other liquid has been 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 bilateral operation, it may be desirable to protect the bottom side of the conductive layer 101. Protection may include, for example, by covering certain areas or providing a drain to divert the solvent away.

[0115] In other embodiments, the final slurry may be dried at least partially elsewhere and then transferred onto the adhesive layer 102 or conductive layer 101 using any suitable technique (e.g., roll-to-roll application) to form the active layer 100. In some embodiments, the wet-assembled slurry may be placed onto an intermediate material having a suitable surface and dried to form a layer (i.e., the active layer 100). While any material having a suitable surface can be used as the intermediate material, exemplary intermediate materials include PTFE because its properties facilitate its subsequent removal from the surface. In some embodiments, a specified layer is formed in a pressing process to provide a layer exhibiting the desired thickness, area, and density.

[0116] In some embodiments, the final paste can be formed into a sheet and coated onto the adhesion layer 102 or the conductive layer 101 as appropriate. For example, in some embodiments, the final paste can be applied using a slit die to control the thickness of the applied layer. In other embodiments, the paste can be applied and then leveled to a desired thickness, for example, using a doctor blade. Various other techniques can be used to apply the paste. For example, coating techniques can include, but are not limited to: doctor blade coating; doctor blade reverse coating; doctor blade coating; slit die coating; direct gravure coating; air knife coating; chamber doctor blade coating; offset gravure coating; single-roll kiss-knife coating; reverse kiss-knife coating using a small-diameter gravure roller; bar coating; three-roll reverse coating (top feed); three-roll reverse coating (fountain die); reverse roller coating, etc.

[0117] The final slurry viscosity can vary depending on the application technique. For example, for blade coating, the viscosity can range from about 1,000 cps to about 200,000 cps. Lip die coating provides a coating with a slurry exhibiting a viscosity between about 500 cps and about 300,000 cps. Reverse kiss coating provides a coating with a slurry exhibiting a viscosity between about 5 cps and 1,000 cps. In some applications, the corresponding layers can be formed in multiple passes.

[0118] In some embodiments, the active layer 100 formed from the final slurry may be compressed (e.g., using a calendering apparatus) before or after application to the electrode 10. In some embodiments, the slurry may be partially or completely dried before or during the compression process (e.g., by applying heat, vacuum, or a combination thereof). For example, in some embodiments, the active layer may be compressed to a final thickness of less than 90%, 80%, 70%, 50%, 40%, 30%, 20%, 10%, or less of its pre-compression thickness (e.g., in the direction normal to the current collector layer 101).

[0119] In various embodiments, when a partially dried layer is formed during the coating or compression process, the layer can then be completely dried (e.g., by applying heat, vacuum, or a combination thereof). In some embodiments, substantially all solvent is removed from the active layer 100.

[0120] In some implementations, the solvents used to form the slurry are recovered and recycled back into the slurry preparation process.

[0121] In some embodiments, the active layer may be compressed, for example, to decompose some of the constituent high aspect ratio carbon elements or other carbonaceous materials, in order to increase the surface area of ​​the corresponding layer. In some embodiments, this compression process may increase one or more of the following: adhesion between layers, ion transport rate within the layer, and surface area of ​​the layer. In various embodiments, compression may be applied before or after the corresponding layer is applied to the electrode 10 or formed on the electrode.

[0122] In some embodiments, when calendering is used to compress the active layer 100, the calendering equipment may be configured with a gap spacing equal to less than 90%, 80%, 70%, 50%, 40%, 30%, 20%, 10% or less of the uncompressed thickness of the layer (e.g., set to about 33% of the uncompressed thickness of the layer). The calendering rolls may be configured to provide suitable pressure, for example, greater than 1 ton / cm roll length, greater than 1.5 ton / cm roll length, greater than 2.0 ton / cm roll length, greater than 2.5 ton / cm roll length, or greater. In some embodiments, the compressed active layer will have a density in the range of 1 g / cc to 10 g / cc or any subrange thereof, such as 2.5 g / cc to 4.0 g / cc. In some embodiments, the calendering process may be carried out at a temperature in the range of 20°C to 140°C or any subrange thereof. In some embodiments, the active layer may be preheated prior to calendering, for example, at a temperature in the range of 20°C to 100°C or any subrange thereof.

[0123] After the electrode 10 is assembled, the energy storage device 10 can be assembled using the electrode 100. The assembly of the energy storage device 10 can follow conventional steps for assembling the electrode with the diaphragm and placing it in a housing such as a can or bag, and may further include additional steps for adding electrolyte and sealing the housing.

[0124] In various embodiments, process 1000 may include any of the following features (individual features or any suitable combination of said features).

[0125] In some embodiments, the initial slurry has a solids content in the range of 0.1 wt% to 20.0 wt% (or any subrange thereof). In some embodiments, the final slurry has a solids content in the range of 10.0 wt% to 80 wt% (or any subrange thereof).

[0126] In various embodiments, the solvent used can be any solvent described herein with respect to the formation of surface treatment 202. In some embodiments, the surfactant material used to form surface treatment 202 is soluble in a solvent exhibiting advantageous properties. For example, in some embodiments, the solvent may include water or an alcohol, such as methanol, ethanol, or 2-propanol (isopropanol, sometimes referred to as IPA), or combinations thereof. In some embodiments, the solvent may include one or more additives for further improving the properties of the solvent, such as low-boiling-point additives, such as acetonitrile (ACN), deionized water, and tetrahydrofuran.

[0127] In some embodiments, if a low-boiling-point solvent is used, the solvent can be rapidly removed using a thermal drying process performed at a relatively low temperature. As those skilled in the art will understand, this can improve the manufacturing speed and / or cost of electrode 10. For example, in some embodiments, the solvent may 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 below or equal to 100°C.

[0128] In some embodiments, the solvent may exhibit other advantageous properties. In some embodiments, the solvent may have a low viscosity, such as less than or equal to 3.0 centipoise, 2.5 centipoise, 2.0 centipoise, 1.5 centipoise, or lower at 20°C. In some embodiments, the solvent may have a low surface tension, such as less than or equal to 40 mN / m, 35 mN / m, 30 mN / m, 25 mN / m, or lower at 20°C. In some embodiments, the solvent may have low toxicity, for example, comparable to that of alcohols such as isopropanol.

[0129] In some embodiments, during the formation of the active layer, the material forming the surface treatment can 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.

[0130] In some embodiments, surface treatment 201 is formed of a material including surfactants of the type described herein.

[0131] In some embodiments, dispersing high aspect ratio carbon elements and surface treatment materials in a solvent to form an initial slurry involves applying forces to the agglomerated carbon elements to cause the elements to slide and separate from each other in a direction transverse to their minor axes. In some embodiments, the technique used to form such a dispersion can be adapted from the technique disclosed in International Patent Publication No. WO / 2018 / 102652, published on 7 June 2018, with further consideration of the teachings described herein.

[0132] In some embodiments, the high aspect ratio carbon element 201 can be functionalized prior to forming a slurry for forming the electrode 10. For example, in one aspect, a method is disclosed comprising dispersing the high aspect ratio carbon element 201 and a surface treatment material in an aqueous solvent to form an initial slurry, wherein the dispersion step results in the formation of a surface treatment on the high aspect ratio carbon; and drying the initial slurry to remove substantially all moisture, thereby producing a dried powder of the high aspect ratio carbon having the surface treatment thereon. In some embodiments, the dried powder can be combined, for example, with a slurry of solvent and active material to form a final solvent of the type described above with reference to method 1000.

[0133] In some embodiments, drying the initial slurry involves lyophilizing the initial slurry (freeze-drying). In some embodiments, the aqueous solvent and the initial slurry are substantially free of substances that would damage the high aspect ratio carbon. In some embodiments, the aqueous solvent and the initial slurry are substantially free of acid. In some embodiments, the initial slurry is substantially composed of high aspect ratio carbon, surface treatment materials, and water.

[0134] Some embodiments further include dispersing a dried powder of surface-treated, high aspect ratio carbon in a solvent and adding an active material to form a secondary slurry; coating the secondary slurry onto a substrate; and drying the secondary slurry to form an electrode active layer. In some embodiments, the foregoing steps can be performed using techniques adapted from those disclosed in International Patent Publication No. WO / 2018 / 102652, published June 7, 2018, with further consideration of the teachings described herein.

[0135] In some embodiments, the final slurry may include polymeric additives such as 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), and polyvinylpyrrolidone (PVP). In some embodiments, the active layer may be treated by applying heat to pyrolyze the additives, such that surface treatment 202 can form a carbonaceous material layer produced by the pyrolysis of the polymeric additives. This carbonaceous material (e.g., graphite or amorphous carbon) layer may adhere (e.g., via covalent bonds) to or otherwise promote adhesion 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 Serial No. 63 / 028982, filed May 22, 2020.

[0136] surfactants

[0137] The techniques described above include the use of surfactants for surface treatment 202 on high aspect ratio carbon nanotubes 201 to promote adhesion to active material particles 300. While several advantageous and suitable surfactants have been described, it should be understood that other surfactant materials, including the following, may also be used.

[0138] 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 in the preparation of surface treatments as described herein. Typically, the surfactants used contain lipophilic nonpolar hydrocarbon groups and polar hydrophilic functional groups. The polar functional groups can be carboxyl groups, ester groups, amine groups, amide groups, imide groups, hydroxyl groups, ether groups, nitrile groups, phosphate groups, sulfate groups, or sulfonic acid groups. Surfactants can be used alone or in combination. Therefore, combinations of surfactants can include anionic surfactants, cationic surfactants, nonionic surfactants, zwitterionic surfactants, amphoteric surfactants, and ampholytic surfactants, provided that a net positive or net negative charge exists in the head region of the surfactant molecule group. In some cases, a single negatively charged or positively charged surfactant is used in the preparation of the electrode compositions of the present invention.

[0139] The surfactants used in the preparation of the electrode compositions of this invention can be anionic, including but not limited to sulfonates such as alkyl sulfonates, alkylbenzene sulfonates, α-olefin sulfonates, paraffin sulfonates, and alkyl ester sulfonates; sulfates such as alkyl sulfates, alkylalkoxy sulfates, and alkylalkoxylated sulfates; phosphates such as monoalkyl phosphates and dialkyl phosphates; phosphonates; and carboxylates such as fatty acids, alkylalkoxycarboxylates, sarcosine salts, hydroxyethanesulfonates, and taurine salts. Specific examples of carboxylates are sodium oleate, sodium cocoyl hydroxyethyl sulfonate, sodium methyl oleoyl taurate, sodium lauryl ether carboxylate, sodium tridecyl ether carboxylate, sodium lauroyl sarcosine, lauroyl sarcosine, and cocoyl sarcosine. Specific examples of sulfates include sodium dodecyl sulfate (SDS), sodium lauryl sulfate, sodium lauryl ether sulfate, sodium tridecyl ether sulfate, sodium tridecyl sulfate, sodium cocoyl sulfate, and sodium monolaurate sulfate.

[0140] Suitable sulfonate surfactants include, but are not limited to, alkyl sulfonates, aryl sulfonates, monoalkyl and dialkyl sulfosuccinates, and monoalkyl and dialkyl sulfosuccinates. Each alkyl group independently contains about two to twenty carbons and can also be ethoxylated with ethylene oxide containing up to about eight units per alkyl group (preferably up to about six units, with an average of, for example, two, three, or four units). Illustrative examples of alkyl sulfonates and aryl sulfonates are sodium tridecylbenzenesulfonate (STBS) and sodium dodecylbenzenesulfonate (SDBS).

[0141] Illustrative examples of sulfosuccinates include, but are not limited to, polydimethylsiloxane copolyol sulfosuccinate, dipentyl sulfosuccinate, didecyl sulfosuccinate, dihexyl sulfosuccinate, diheptyl sulfosuccinate, dihexyl sulfosuccinate, diisobutyl sulfosuccinate, dioctyl sulfosuccinate, C12-15 alkanol polyether sulfosuccinate, cetearyl sulfosuccinate, cocoyl glucoside sulfosuccinate, cocoyl butyl glucoside-10 sulfosuccinate, decanol polyether-5 sulfosuccinate, decanol polyether-6 sulfosuccinate, dihydroxyethyl sulfosuccinoyl undecenoate, hydrogenated cottonseed oil glyceryl ester sulfosuccinate, isodecanyl sulfosuccinate, and isobutyl sulfosuccinate. Sulfosinate, lanolin ether-5 sulfosuccinate, lauryl ether sulfosuccinate, lauryl ether-12 sulfosuccinate, lauryl ether-6 sulfosuccinate, lauryl ether-9 sulfosuccinate, lauryl sulfosuccinate, nonyl alcohol ether-10 sulfosuccinate, oleyl alcohol ether-3 sulfosuccinate, oleyl alcohol sulfosuccinate, PEG-10 lauryl citrate sulfosuccinate, sitosterol ether-14 sulfosuccinate, stearyl alcohol sulfosuccinate, tallow, tridecyl alcohol sulfosuccinate, triglyceride sulfosuccinate, diethylene glycol ricinoleate sulfosuccinate, di(1,3-dimethylbutyl) sulfosuccinate, and silicone copolyol sulfosuccinate.

[0142] Illustrative examples of sulfosuccinates include, but are not limited to, lauramide-MEA sulfosuccinate, oleamide-PEG-2 sulfosuccinate, cocamido-MIPA-sulfosuccinate, cocamido-PEG-3 sulfosuccinate, isostearamide-MEA-sulfosuccinate, isostearamide-MIPA-sulfosuccinate, lauramide-MEA-sulfosuccinate, lauramide-PEG-2 sulfosuccinate, lauramide-PEG-5 sulfosuccinate, myristamide-MEA-sulfosuccinate, oleamide-MEA sulfosuccinate, oleamide-PIPA sulfosuccinate, and oleamide-PE G-2 sulfosuccinate, palmamide-based PEG-2 sulfosuccinate, palm oleamide-based PEG-2 sulfosuccinate, PEG-4 cocoamide-based MIPA-sulfosuccinate, castor oil oleamide-based MEA-sulfosuccinate, stearamide-based MEA-sulfosuccinate, stearyl sulfosuccinate, tallow oleamide-based MEA-sulfosuccinate, tallow sulfosuccinate, tallow oleamide-based MEA-sulfosuccinate, undecyleneamide MEA-sulfosuccinate, undecyleneamide PEG-2 sulfosuccinate, wheat germ oleamide MEA-sulfosuccinate, and wheat germ oleamide PEG-2 sulfosuccinate.

[0143] Some examples of commercially available sulfonates are AEROSOL® OT-S, AEROSOL® OT-MSO, AEROSOL® TR70% (Cytec Inc., West Paterson, NJ), NaSul CA-HT3 (King Industries, Norwalk, Connecticut), and C500 (Crompton Co., West Hill, Ontario, Canada). AEROSOL® OT-S is sodium dioctyl sulfosuccinate in petroleum distillate form. AEROSOL® OT-MSO also contains sodium dioctyl sulfosuccinate. AEROSOL® TR70% is a mixture of ethanol and water containing sodium ditridecyl sulfosuccinate. NaSul CA-HT3 is a dinonylnaphthalenesulfonic acid / calcium carboxylate complex. C500 is an oil-soluble calcium sulfonate.

[0144] Alkyl or alkyl refers to a saturated hydrocarbon having one or more carbon atoms, including straight-chain alkyl (e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, etc.), cyclic alkyl (or cycloalkyl, or alicyclic or carbocyclic group) (e.g., cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, etc.), branched alkyl (e.g., isopropyl, tert-butyl, sec-butyl, isobutyl, etc.), and alkyl-substituted alkyl (e.g., alkyl-substituted cycloalkyl and cycloalkyl-substituted alkyl).

[0145] Alkyl groups can include both unsubstituted alkyl groups and substituted alkyl groups. A substituted alkyl group is an alkyl group having a substituent that replaces one or more hydrogens on one or more carbons of the hydrocarbon backbone. Such substituents may include, for example, alkenyl, alkynyl, halogen, hydroxyl, alkyl carbonyloxy, aryl carbonyloxy, alkoxy carbonyloxy, aryloxy, aryloxy carbonyloxy, carboxylic acid ester, alkyl carbonyl, aryl carbonyl, alkoxy carbonyl, amino carbonyl, alkyl amino carbonyl, dialkyl amino carbonyl, alkyl thio carbonyl, alkoxy, phosphate ester, phosphonic acid, phosphonite, cyano, amino (including alkyl amino, dialkyl amino, aryl amino, diaryl amino and alkyl aryl amino), amide (including alkyl carbonyl amino, aryl carbonyl amino, carbamoyl and urea), imino, mercapto, alkyl thio, aryl thio, thiocarboxylic acid ester, sulfate ester, alkyl sulfinyl, sulfonate, amino sulfonyl, sulfonamide, nitro, trifluoromethyl, cyano, azide, heterocyclic, alkyl aryl or aromatic (including heteroaromatic) groups.

[0146] In some embodiments, the substituted alkyl group may include a heterocyclic group. The heterocyclic group comprises a closed-ring structure similar to a carbocyclic group, wherein one or more carbon atoms in the ring are elements other than carbon, such as nitrogen, sulfur, or oxygen. The heterocyclic group may be saturated or unsaturated. Exemplary heterocyclic groups include azirropropane, ethylene oxide (epoxide, oxirane), thiohexacyclopropane (cyclic sulfide), diazirropropane, azirrobutane, oxicyclobutane, thiohexacyclobutane, dioxicyclobutane, dithicyclobutene, azopyridine, pyrrolidine, pyrrololine, oxicyclopentane, dihydrofuran, and furan.

[0147] For anionic surfactants, the counterion is typically sodium, but can alternatively be potassium, lithium, calcium, magnesium, ammonium, amines (primary, secondary, tertiary, or quaternary amines), or other organic bases. Exemplary amines include isopropylamine, ethanolamine, diethanolamine, and triethanolamine. Mixtures of the above cations can also be used.

[0148] The surfactants used in the preparation of the materials of this invention can be cationic. Such cationic surfactants include, but are not limited to, compounds containing pyridinium ions and organic primary, secondary, tertiary, or quaternary amines. For cationic surfactants, counterions can be, for example, chloride, bromine, methyl sulfate, ethyl sulfate, lactate, saccharinate, acetate, and phosphate. Examples of cationic amines include polyethoxylated oleylamine / stearylamine, ethoxylated tallow amine, cocoyl alkylamine, oleylamine, and tallow alkylamine, and mixtures thereof.

[0149] Examples of quaternary ammonium compounds with a single long alkyl group are hexadecyltrimethylammonium bromide (CTAB), benzyldodecyldimethylammonium bromide (BddaBr), benzyldimethylhexadecylammonium chloride (BdhaCl), dodecyltrimethylammonium bromide, myristyltrimethylammonium bromide, stearyldimethylbenzylammonium chloride, oleyldimethylbenzylammonium chloride, lauryltrimethylammonium methyl methyl sulfate (also known as cocoyltrimethylammonium methyl methyl sulfate), hexadecyl-dimethylhydroxyethylammonium dihydrogen phosphate, and barium sulfate. Basu oleamidopropyl benzyl dimethyl ammonium chloride, cocoyl trimethyl ammonium chloride, distearyl dimethyl ammonium chloride, wheat germ oleamidopropyl benzyl dimethyl ammonium chloride, stearyl octyl dimethyl ammonium sulfate, isostearamidopropyl benzyl dimethyl ammonium chloride, dihydroxypropyl PEG-5 linoleyl ammonium chloride, PEG-2 stearyl methyl ammonium chloride, behenyl trimethyl ammonium chloride, diceryl dimethyl ammonium chloride, tallow trimethyl ammonium chloride, and behenamidopropyl ethyl dimethyl ethyl ammonium sulfate.

[0150] Examples of quaternary ammonium compounds having two long alkyl groups are didodecyl dimethylammonium bromide (DDAB), distearyl dimethylammonium chloride, diceryl dimethylammonium chloride, stearyl octyl dimethylammonium sulfate, dihydropalmitoyl ethyl hydroxyethyl methylammonium methyl sulfate, dipalmitoyl oxyethyl hydroxyethyl methylammonium methyl sulfate, dioleoyl ethyl hydroxyethyl methylammonium methyl sulfate, and hydroxypropyl distearyl dimethylammonium chloride.

[0151] Quaternary ammonium compounds of imidazoline derivatives include, for example, isostearylbenzylimidazoline nitrogen chloride, cocoylbenzylhydroxyethylimidazoline nitrogen chloride, cocoylhydroxyethylimidazoline nitrogen PG-chloride phosphate, and stearylhydroxyethylimidazoline nitrogen chloride. Other heterocyclic quaternary ammonium compounds, such as dodecylpyridine chloride, amprolium hydrochloride (AH), and benzenethonium hydrochloride (BH), may also be used.

[0152] The surfactants used in the preparation of the materials of this invention can be nonionic, including but not limited to polyalkylene oxide carboxylate, fatty acid ester, fatty alcohol, ethoxylated fatty alcohol, poloxamer, alkanolamide, alkoxylated alkanolamide, polyethylene glycol monoalkyl ether, and alkyl polysaccharides. Polyalkylene oxide carboxylate has one or two carboxylate moieties and a polyalkylene oxide moiety, each carboxylate moiety having about 8 to 20 carbons, and the polyalkylene oxide moiety containing about 5 to 200 alkylene oxide units. Ethoxylated fatty alcohols contain an ethylene oxide moiety and a fatty alcohol moiety, the ethylene oxide moiety containing about 5 to 150 ethylene oxide units, and the fatty alcohol moiety having about 6 to about 30 carbons. The fatty alcohol moiety can be cyclic, linear, or branched, and can be saturated or unsaturated. Some examples of ethoxylated fatty alcohols include oleyl alcohol polyether alcohol, stearyl alcohol polyether alcohol, lauryl alcohol, and isocetyl alcohol glycol ethers. Poloxamer is a block copolymer of ethylene oxide and propylene oxide, having about 15 moles to about 100 moles of ethylene oxide. Alkyl polysaccharide (“APS”) surfactants (e.g., alkyl polysaccharide glycosides) contain a hydrophobic group having about 6 to about 30 carbons and a polysaccharide (e.g., a polysaccharide glycoside) as a hydrophilic group. An example of a commercial nonionic surfactant is FOA-5 (Octel Starreon LLC., Littleton, Colorado).

[0153] Specific examples of suitable nonionic surfactants include alkanolamides such as cocamidodiethanolamide (“DEA”), cocamidomonoethanolamide (“MEA”), cocamidomonoisopropanolamide (“MIPA”), PEG-5 cocamidoamide MEA, lauramide DEA, and lauramide MEA; alkylamine oxides such as laurylamine oxide, cocamidoamide oxide, cocamidopropylamine oxide, and lauramidepropylamine oxide; sorbitan laurate and 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; and alkyl polyglycosides such as decyl glucoside, lauryl glucoside, and coco-glucoside.

[0154] The surfactant used in the preparation of the materials of this invention can be zwitterionic, that is, having both positive and negative charges on the same molecule. The positively charged group can be quaternary ammonium, quaternary phosphorus, or quaternary sulfonium, while the negatively charged group can be carboxylate, sulfonate, sulfate, phosphate, or phosphonate. Similar to other classes of surfactants, the hydrophobic portion can contain one or more long straight-chain cyclic or branched aliphatic chains consisting of about 8 to 18 carbon atoms. Specific examples of zwitterionic surfactants include alkyl betaines, such as cocodimethylcarboxymethyl betaine, lauryldimethylcarboxymethyl betaine, lauryldimethylα-carboxyethyl betaine, cetyldimethylcarboxymethyl betaine, lauryl bis-(2-hydroxyethyl)carboxymethyl betaine, stearyl bis-(2-hydroxypropyl)carboxymethyl betaine, oleyldimethylγ-carboxypropyl betaine, lauryl bis-(2-hydroxypropyl)α-carboxyethyl betaine, and amamidopropyl betaine; and alkyl dimethyl sulfonyl betaines, such as cocodimethyl sulfonyl betaine, stearyl dimethyl sulfonyl betaine, lauryl dimethyl sulfonyl betaine, lauryl bis-(2-hydroxyethyl)sulfonyl betaine, and alkylamidopropyl hydroxydimethyl sulfonyl betaine.

[0155] The surfactants used in the preparation of the materials of the present invention can be amphoteric. Examples of suitable amphoteric surfactants include ammonium salts or substituted ammonium salts of alkyl amphoteric carboxyglycinate and alkyl amphoteric carboxypropionate, alkyl amphoteric dipropionate, alkyl amphoteric diacetate, alkyl amphoteric glycinate and alkyl amphoteric propionate, and alkyl iminopropionate, alkyl imino dipropionate and alkyl amphoteric propyl sulfonate. Specific examples are cocoamphoacetate, cocoamphoacetate, cocoamphoacetate, lauroyl amphoteric diacetate, lauroyl amphoteric dipropionate, lauroyl amphoteric diacetate, cocoamphoacetic propyl sulfonate, hexanoyl amphoteric diacetate, hexanoyl amphoteric diacetate, hexanoyl amphoteric dipropionate and stearoyl amphoteric acetate.

[0156] The surfactants used in the preparation of the materials of the present invention can also be polymers, such as N-substituted polyisobutylene succinimide and succinate, alkyl methacrylate vinylpyrrolidone copolymer, alkyl methacrylate-dialkylaminoethyl methacrylate copolymer, alkyl methacrylate polyethylene glycol methacrylate copolymer, polystearamide and polyethyleneimine.

[0157] The surfactant used in the preparation of the materials of the present invention can also be a polysorbate type nonionic surfactant, such as 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).

[0158] The surfactants used in the preparation of the materials of this invention can be oil-based dispersants, including alkyl succinimides, succinates, high molecular weight amines, Mannich bases, and phosphoric acid derivatives. Some specific examples are polyisobutylene succinimid-polyethylene polyamine, polyisobutylene succinate, polyisobutylene hydroxybenzyl-polyethylene polyamine, and bis-hydroxypropyl phosphate.

[0159] The surfactants used in the preparation of the materials of the present invention can be combinations of two or more surfactants of the same or different types, wherein the surfactants are selected from the group consisting of: anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, amphoteric surfactants, and charged amphoteric surfactants. Suitable examples of combinations of two or more surfactants of the same type include, but are not limited to, mixtures of two anionic surfactants, mixtures of three anionic surfactants, mixtures of four anionic surfactants, mixtures of two cationic surfactants, mixtures of three cationic surfactants, mixtures of four cationic surfactants, mixtures of two nonionic surfactants, mixtures of three nonionic surfactants, mixtures of four nonionic surfactants, mixtures of two amphoteric surfactants, mixtures of three amphoteric surfactants, mixtures of four amphoteric surfactants, mixtures of two amphoteric surfactants, mixtures of three amphoteric surfactants, mixtures of four amphoteric surfactants, mixtures of two charged amphoteric surfactants, mixtures of three charged amphoteric surfactants, and mixtures of four charged amphoteric surfactants.

[0160] Thin polymer layer material

[0161] The techniques described above include using polymers to form a surface treatment 201 on high aspect ratio carbon nanotubes to promote adhesion to the active material particles 300. While several advantageous and suitable polymers have been described, it should be understood that other polymeric materials, including the following, may also be used.

[0162] The polymers used in the preparation of the materials of this invention can be polymeric materials, such as water-treatable polymeric materials. In various embodiments, any of 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), and polyvinylpyrrolidone (PVP). In some embodiments, another exemplary polymeric material is a fluoroacrylic acid mixed lactic acid (TRD202A), supplied by JSR Corporation.

[0163] Example

[0164] The following non-limiting embodiments further illustrate the application of the teachings of this disclosure. In the following embodiments, the term "binder-free" or "binder-free" electrode, of the type described in detail above, characterized by a 3D matrix or scaffold of high aspect ratio carbon, is used as a reference, referring to a surface treatment on the high aspect ratio carbon that promotes adhesion of the active material to the scaffold without the need for a bulk polymer binder such as PVDF.

[0165] As used below, the term C-rate refers to a measure of the rate at which the battery discharges relative to its maximum capacity. A 1C-rate means that the discharge current will cause the entire battery to discharge in one hour. For a battery with a capacity of 100 ampere-hours, this is equivalent to a discharge current of 100 amperes.

[0166] Example 1 - Electric Vehicle Battery Unit

[0167] The following battery cell is suitable for electric vehicles (“EVs”). This battery cell combines cathode and anode technologies of the type described herein for use in applications such as EVs. Key high-level benefits include lower manufacturing costs, higher energy density, excellent power density, and wide operating temperature range. These benefits stem from the methods described herein for manufacturing the battery electrodes, which eliminate the use of PVDF polymer binders and toxic solvents such as N-methyl-2-pyrrolidone (NMP). As a result, significant performance advantages in range, charging speed, and acceleration are achieved for the end user through a lower-cost, less capital-intensive manufacturing process that is safer for battery manufacturers.

[0168] The teachings of this paper provide a technological platform for manufacturing electrodes for energy storage, which can exhibit the following advantages: reduced manufacturing costs and the resulting LIB's power density per kWh; increased energy density achieved by combining a cathode with a thick coating and a high-capacity anode characterized by high-performance active materials such as Si or SiOx; and fast charging. The teachings of this paper also provide a scalable technique for improving the power density of energy storage by removing conventional polymer binders from the active material coating.

[0169] Conventional electrodes for LiB are manufactured by mixing active materials, conductive additives, and polymer binders in a slurry. Conventional cathodes are manufactured using NMP-based slurries and PVDF polymer binders. These binders have very high molecular weights and promote the cohesion of active material particles and their adhesion to the current collector foil through two main mechanisms: 1) entanglement promoted by long polymer chains, and 2) hydrogen bonding between the polymer, the active material, and the current collector. However, the polymer binder-based approach has significant performance drawbacks: power density, energy density, and manufacturing cost.

[0170] The teachings of this article provide for electrodes without PVDF binders in the cathode or other conventional binders in the anode. Instead, as detailed above, a 3D carbon scaffold or matrix holds the active material particles together to form a cohesive layer that is also firmly attached to the metal current collector. This type of active material structure is produced during slurry preparation and subsequently during roll-to-roll (“R2R”) coating and drying processes. One of the main advantages of this technique is its scalability and “drop-in” nature, as it is compatible with conventional electrode manufacturing processes.

[0171] The 3D carbon matrix is ​​formed during slurry preparation using the techniques described herein: appropriately dispersing high aspect ratio carbon materials, and employing, for example, a two-step slurry preparation process (as referenced above). Figure 6 The slurry (of the aforementioned type) undergoes chemical functionalization. This chemical functionalization is designed to form a self-assembled structure with a surface composed of active material particles, such as NMC particles for the cathode or silicon (“Si”) or silicon oxide (“SiOx”) particles in the anodic case. The slurry thus formed can be based on an alcohol solvent for the cathode and water for the anode, and this solvent is readily evaporated and disposed of during the manufacturing process. Electrostatic interactions promote the self-organized structure in the slurry, and after the drying process, surface treatment (e.g., functional groups on the matrix) and the strong entanglement of the active material in the carbon matrix promote bonding between the carbon matrix with the active material particles and the current collector surface.

[0172] As those skilled in the art will understand, the mechanical properties of the electrode can be readily altered by tuning surface functionalization relative to the entanglement effect, depending on the application and mass load requirements.

[0173] After coating and drying, the electrode undergoes a rolling process to control the density and porosity of the active material. In the NMC cathode electrode, a density of 3.5 g / cc or greater and a porosity of 20% or greater can be achieved. The porosity can be optimized according to the mass loading and LIB cell requirements. For the SiOx / Si anode, its porosity is specifically controlled to accommodate the expansion of the active material during the lithiation process.

[0174] In some typical applications, the teachings in this paper can provide a reduction of up to 20% in energy consumption per kWh. Higher electrode flux is achieved through the use of readily evaporable, environmentally friendly solvents, and, more importantly, a significant reduction in energy consumption is realized through long dryers. Conventional NMP recovery systems are also greatly simplified when using alcohols or other solvent mixtures.

[0175] This paper teaches the use of a 3D matrix that significantly enhances electrode conductivity by 10 to 100 times compared to electrodes using conventional binders such as PVDF, enabling rapid charging at certain battery levels. Using this technique, thick electrode coatings of up to 150 μm (or greater) per side can be achieved in the cathode of a current collector. The combination of the solvent used in the slurry with the strong 3D carbon matrix is ​​designed to achieve a thick wet coating that does not crack during the drying step. The thick cathode combined with the high-capacity anode is what allows for a significant leap in energy density, reaching 400 Wh / kg or higher.

[0176] Fast charging is achieved by combining high-capacity anodes (Si / SiOx) that have been lithium-ionized through an alloying process and by reducing the overall impedance of the battery cell when combining the anode and cathode, as described herein. The teachings of this paper provide fast charging through electrodes with high conductivity, and particularly high-conductivity cathode electrodes.

[0177] An exemplary embodiment includes a Li-ion battery energy storage device in the form of a pouch cell, the Li-ion battery energy storage device combining a Ni-rich NMC active material in the cathode with a SiOx and graphite blended active material in the anode, wherein both the anode and cathode are manufactured using a 3D carbon matrix process as described herein.

[0178] Figure 7A schematic diagram of an electrode arrangement for a pouch cell assembly is shown. As illustrated, a double-sided cathode, using a polymer-free cathode layer on opposite sides of an aluminum foil current collector, is positioned between two single-sided anodes. Each single-sided anode has a polymer-free anode layer disposed on a copper foil current collector. The electrodes are separated by a permeable membrane material (not shown) wetted with an electrolyte (not shown). This arrangement can be incorporated into pouch cell units of a type well-known in the art.

[0179] These devices may be characterized by: a high-mass-loaded Ni-rich NMC cathode electrode and its manufacturing method: mass load = 20-30 mg / cm³ 2 Specific capacity > 210 mAh / g. Electrode based on SiOx / graphite anode (SiOx content = approximately 20 wt.%) and its material synthesis and manufacturing method: mass loading 8-14 mg / cm³. 2 Reversible specific capacity ≥ 550mAh / g. Long-life performance of Li-ion based electrolyte with SiOx / graphite anode specifically designed for batteries: -30℃ to 60℃. High energy, high power density and long cycle life Ni-rich NMC cathode / SiOx + graphite / carbon + based Li-ion battery pouch cell: capacity ≥ 5Ah, specific energy ≥ 300Wh / kg, energy density ≥ 800Wh / L, and cycle life of over 500 cycles at 1C charge-discharge rate and ultra-high power fast charge-discharge C rate (up to 5C rate) capability. Figure 8 This document summarizes the performance parameters of this type of pouch cell.

[0180] Example 2 – Comparative Performance of NMC811 Lithium-ion Batteries

[0181] As detailed above, the teachings of this paper provide electrodes configured with advanced 3-D high aspect ratio carbon-bonded structures that eliminate the need for polymer binders, providing greater power, energy density (e.g., through thicker electrodes and higher mass loading of active materials), and performance in extreme environments compared to conventional battery electrode designs. High-performance Li-ion battery energy storage devices are designed and manufactured with an optimized capacity ratio design consisting of binder-free cathode / anode electrodes, pre-lithiated anode electrodes, a wide operating temperature electrolyte (e.g., -30 to 60°C), and an optimized test-forming process.

[0182] As described herein, the electrode is manufactured by completely removing high molecular weight polymers (such as PVDF) and toxic NMP solvents from the active material layer. This significantly improves LiB performance while reducing manufacturing costs and capital expenditures associated with mixing, coating and drying, NMP solvent recovery, and calendering. In the electrode implementation, a 3D nanoscale carbon matrix acts as a mechanical scaffold for the electrode active material and mimics polymer chain entanglement. Chemical bonds also 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 conductive, enabling the achievement of very high power (high C-rate). This scaffold structure is also more suitable for producing thick electrode active materials, a powerful way to increase the energy density of LiB battery cells.

[0183] In this embodiment, in accordance with the teachings of this disclosure, a binder-free cathode characterized by NMC811 as the active material is produced, and said cathode is incorporated into a Li-ion battery (LIB). The battery cell is characterized by a graphite anode of a conventional type known in the art. (Refer to the above...) Figure 7 Use of description Figure 9 The parameters summarized in the text are used to construct the battery cell. A conventional electrolyte is used, which consists of a solvent mixture of ethylene carbonate and dimethyl carbonate containing 1M LiPF6 with 1% ethylene carbonate additive. In comparison, a battery cell identical in all other respects was produced using a PVDF-based binder. The performance of the battery cells is compared below, demonstrating the significant advantages of the binder-free cathode battery cell.

[0184] like Figure 10 The results summarized show that, based on a 20Ah cell design and a graphite anode, binder-free cell structures can achieve a specific energy of up to 320Wh / kg and a cycle life of over 2,000 cycles at a 2C charge / discharge rate. In contrast, at the cell level, conventional binder-based cathode cells can only achieve 100-250Wh / kg in terms of specific energy.

[0185] The binder-free cathode cell exhibits an ultra-high power fast charge-discharge C-rate of up to 5C and a capacity retention of >50%. Figure 10A comparison of charge-discharge curves at different C rates is shown for a binder-free cathode cell (left) and a conventional binder-based cathode cell (right). The binder-free cathode cell charge-discharge curve shows that at a 5C rate, the combined charge-discharge capacity retention exceeds 60%. Therefore, individual discharge or charge will exhibit even higher capacity retention. Note that in the provided embodiment, a conventional graphite anode is used, and preliminary experimental results show that a 10C charging rate can be achieved when a Si-dominant anode is combined with the NMC811 cathode used in this embodiment.

[0186] Figure 11 A comparison of the cycle life of the battery cells described above is shown. The battery cells were repeatedly cycled between 2.75V and 4.2V at 25°C, and the discharge capacity was recorded. The binder-free cathode battery cell exhibited a lifespan of over 2,000 cycles and a discharge capacity loss of less than 20%. In contrast, the binder-based cathode battery cell showed a discharge capacity loss of over 20% after only about 1,000 cycles.

[0187] Example 3 – Comparison of Pocket-Type Half-Cell Cells

[0188] The binder-free cathode electrode of the type described herein can advantageously achieve high-quality loading; for example, 45 mg / cm² can be achieved on each side of the NMC811 active material. 2 The mass loading. This embodiment illustrates the experimental results, which demonstrate the performance of this high-mass-loaded, binder-free electrode compared to the performance of a control electrode characterized by PVDF binder and NMC811 active material.

[0189] For comparison, Figure 12 The type of half-cell shown is constructed using a single-sided cathode (without binder or binder-based control) and lithium foil on a copper substrate as the counter electrode of the cell. The half-cell was subjected to charge rate tests at various current densities, and the results are summarized below.

[0190] Figure 13 This is a graph showing the potential (with Li / Li+ potential as a reference) versus specific capacity of a binder-free cathode half-cell (solid trace) and a reference binder-based cathode half-cell (dashed trace) at various current densities. At all current densities (and therefore all C-rates), the binder-free cathode half-cell exhibits better performance (as indicated by the relative rightward shift of the traces).

[0191] Figure 14This is a graph showing the potential (with Li / Li+ potential as a reference) versus volumetric capacity of a binder-free cathode half-cell (solid trace) and a reference binder-based cathode half-cell (dashed trace) at various current densities. At all current densities (and therefore all C-rates), the binder-free cathode half-cell exhibits better performance (as indicated by the relative rightward shift of the traces).

[0192] Figure 15 A graph showing the volumetric capacity versus current density for a binder-free cathode half-cell (upper trace) and a reference binder-based cathode half-cell (lower trace) is presented. The binder-free cathode half-cell exhibits better performance at all current densities (and therefore all C-rates), with the relative performance gap widening at higher C-rates.

[0193] Figure 16 The Nyquist plots of electrochemical impedance spectroscopy for several binder-free cathode half-cell units (traces marked with squares, circles, and triangles) and a reference binder-based cathode half-cell unit are shown. The binder-free cathode half-cell units exhibit significantly better performance than the reference cell unit.

[0194] As can be seen from the figure, when the current density increases from 0.5 mA / cm², the... 2 Increased to 10 mA / cm 2 At (1.2 C rate), the discharge capacity retention of the binder-free NMC811 electrode is significantly higher than that of the binder-based PVDF control NMC811 electrode, even though both electrodes have the same 45 mg / cm³ discharge capacity retention. 2 The same applies to the mass load. Note that this C-rate test, conducted at various current densities, presents a relative comparison between a conventional binder-based PVDF cathode and a binder-free cathode, and that the C-rate test does not reflect the absolute C-rate performance in a full cell configuration, such as that presented in Examples 1 and 2 above.

[0195] Example 4

[0196] In this embodiment, the energy storage device comprises an electrode that is PVDF-free and does not use NMP as a solvent to promote the formation of the active layer. The anode comprises a silicon-rich anode active material. The active material of the anode is a SiOx / graphite anode (SiOx content = about 20 wt.%) (referred to as SiGr). Lithium iron phosphate oxide (LFP, one variant of which has the chemical formula LiFePO4) is used in some cathodes. High-quality, Ni-rich NMC active material is used in some other cathodes. The battery cell has an energy density of 220 Wh / kg to 350 Wh / kg, preferably 2330 Wh / kg to 320 Wh / kg. The battery cell has a volumetric energy density of 500 Wh / L to 900 Wh / L, preferably 550 Wh / L to 860 Wh / L.

[0197] The electrode slurry is manufactured using a water-based electrode slurry. No PVDF binder and no NMP are used in the formation of the slurry, which ultimately forms the active layer of the electrode.

[0198] The energy storage device (with an LFP cathode) has a concentration of 16 mg / cm³. 2 Up to 35 mg / cm 2 The areal density of the electrode active material is high, and it can be coated without cracking. A capacity of 2.0 mAh / cm² can be achieved. 2 Up to 5.8mAh / cm 2 The area capacity, preferably, is 2.4 mAh / cm². 2 Up to 5.4mAh / cm 2 The area capacity. Battery cell capacity can vary from 1600mAh to 1700mAh.

[0199] Compared to cathodes containing LFP and graphite, combining an LFP cathode electrode with a silicon-graphite anode in an energy storage device increases the energy density by 30%. Pouch cell units based on LFP (cathode) and SiGr (anode) can achieve energy densities greater than 220 Wh / kg, preferably greater than 250 Wh / kg, and volumetric energy densities greater than 540 Wh / L, preferably greater than 550 Wh / L.

[0200] As can be seen from the results shown above, the energy storage device containing an anode comprising 10 wt% to 30 wt%, preferably 15 wt% to 25 wt% SiOx (silicon dioxide) (where x ranges from 1.2 to 3.5, preferably 1.75 to 2.5) based on the electrode active layer (e.g., the anode) and 60 wt% to 90 wt%, preferably 65 wt% to 85 wt% based on the anode active layer, exhibits excellent energy density. The cathode contains LFP, and the energy storage device does not contain PVDF binder. It also does not contain any solvents containing NMP. Water is used to manufacture the slurry used in the energy storage device.

[0201] Graphite (graphite of SiGr) is any carbonaceous material described herein. It may include graphite particles, carbon nanotubes, carbon black, graphene, as described above.

[0202] in conclusion

[0203] Any orientation terms provided herein are for illustrative purposes only and do not limit the invention. For example, a “top” layer may also be referred to as a second layer, and a “bottom” layer may also be referred to as a first layer. Other names and arrangements may be used without limiting the teachings herein.

[0204] Various other components may be included and invoked when providing aspects of the teachings herein. For example, additional materials, combinations of materials, and / or the omission of materials may be used to provide additional implementations within the scope of the teachings herein.

[0205] The various modifications taught in this paper can be implemented. Generally, modifications can be designed to meet the needs of users, designers, manufacturers, or other similar stakeholders. Modifications may be designed to meet specific performance criteria deemed important by these parties. Similarly, the acceptability of performance should be evaluated by appropriate users, designers, manufacturers, or other similar stakeholders.

[0206] While some chemicals may be listed in this article for providing a certain function, a given chemical may also be used for another purpose.

[0207] When describing elements of the invention or embodiments thereof, the articles “a,” “an,” and “the” are intended to refer to one or more of the elements present. Similarly, the adjective “another” is intended to refer to one or more elements when used to describe an element. The terms “including” and “having” are intended to be inclusive, allowing for the presence of additional elements besides those listed. As used herein, the term “exemplary” is not intended to imply a superlative example. Rather, “exemplary” refers to an embodiment that is one of many possible embodiments.

[0208] The entire contents of each of the publications and patent applications mentioned above are incorporated herein by reference. In the event of any conflict between any cited document and the contents of this disclosure, the contents of this disclosure shall prevail.

[0209] Note that, unless expressly indicated by the use of the words “means for” or “steps for” in the respective claims, any functional language used in the appended claims is not intended to be construed as “means plus function” language in accordance with 35 USC §112(f).

[0210] Although the invention has been described with reference to exemplary embodiments, it should be understood that various changes can be made and elements of the invention can be substituted with equivalents without departing from the scope of the invention. For example, in some embodiments, one of the foregoing layers may include multiple layers therein. Furthermore, many modifications will be understood to adapt particular apparatus, situations, or materials to the teachings of the invention without departing from the basic scope of the invention. Therefore, the invention is not intended to be limited to the specific embodiments disclosed as the best mode contemplated for carrying out the invention, but rather the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. An apparatus comprising: Electrode active layer, the electrode active layer comprising: A network of high aspect ratio carbon elements, wherein the high aspect ratio carbon elements define the void space within the network; Multiple electrode active material particles, said multiple electrode active material particles being disposed in the void spaces within the network and entangled in the network; and A surface treatment on the surface of the high aspect ratio carbon element promotes adhesion between the high aspect ratio carbon element and the active material particles.

2. The device of claim 1, wherein the high aspect ratio carbon element comprises elements each having two primary dimensions and one secondary dimension, wherein the length ratio of each primary dimension is at least 10 times the length ratio of the secondary dimension.

3. The device of claim 1, wherein the high aspect ratio carbon element comprises elements each having one primary dimension and two secondary dimensions, wherein the length ratio of each of the primary dimensions is at least 10 times the length ratio of each of the secondary dimensions.

4. The device according to claim 1, wherein the high aspect ratio carbon element comprises carbon nanotubes or carbon nanotube bundles.

5. The device according to claim 1, wherein the high aspect ratio carbon element comprises graphene sheets.

6. The device according to claim 1, wherein the electrode active layer contains less than 10% by weight of a polymer binder, the polymer binder being disposed in the void space.

7. The device according to claim 1, wherein the electrode active layer contains less than 1% by weight of a polymer binder, the polymer binder being disposed in the void space.

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

9. The device according to claim 1, wherein the electrode active layer is substantially free of polymer material.

10. The apparatus of claim 1, wherein the surface treatment comprises a material soluble in a solvent with a boiling point below 202°C.

11. The apparatus of claim 1, wherein the surface treatment comprises a material soluble in a solvent with a boiling point below 185°C.

12. The apparatus of claim 1, wherein during the formation of the active layer, the material forming the surface treatment is dissolved in a solvent with a boiling point below 202°C.

13. The apparatus of claim 1, wherein during the formation of the active layer, the material forming the surface treatment is dissolved in a solvent with a boiling point below 185°C.

14. The apparatus of claim 1, wherein during the formation of the active layer, the material forming the surface treatment is dissolved in a solvent containing isopropanol.

15. The apparatus of claim 1, wherein 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.

16. The device of claim 1, wherein the active material particles comprise lithium metal oxide.

17. The device according to claim 16, wherein the lithium metal oxide is lithium cobalt oxide, lithium nickel manganese cobalt oxide, lithium manganese oxide, lithium nickel cobalt aluminum oxide, lithium titanate oxide, lithium iron phosphate oxide, or lithium nickel cobalt aluminum oxide.

18. The apparatus of claim 17, wherein the lithium cobalt oxide is LiCoO2, the lithium nickel manganese cobalt oxide is LiNiMnCo; the lithium manganese oxide is LiMn2O4 or Li2MnO3, the lithium nickel cobalt aluminum oxide is LiNiCoAlO2, and the lithium titanate oxide is Li4Ti5O4. 12 Furthermore, the lithium iron phosphate oxide is LiFePO4.

19. The device according to claim 18, wherein the LiNiMnCo is LiNi x Mn y Co 1-x-y , where x is equal to or greater than about 0.7, and where y is about 0.

1.

20. The device according to claim 18, wherein the LiNiMnCo is LiNi 0.33 Mn 0.33 Co 0.33 O2, LiNi 0.5 Mn 0.3 Co 0.2 O2 or LiNi 0.6 Mn 0.2 Co 0.2 O2.

21. The device of claim 1, wherein the network is at least 99% by weight carbon and exhibits electrical connectivity above a percolation threshold, wherein the network defines one or more highly conductive paths having a length greater than 100 µm.

22. The apparatus of claim 1, wherein the surface treatment comprises a surfactant forming a surfactant layer bonded to the carbon element and comprising a plurality of surfactant elements, each surfactant element having a hydrophobic end and a hydrophilic end, wherein the hydrophobic end is disposed proximal to the surface of the carbon element and the hydrophilic end is disposed distal to the surface of the carbon element.

23. The device of claim 22, wherein the surfactant is an ionic surfactant compound comprising at least one selected from the list of: hexadecyltrimethylammonium tetrafluoroborate, hexadecyltrimethylammonium tetrafluoroborate, N-(cocoyl)-N,N,N-trimethylammonium methyl sulfate, cocamidopropyl betaine, hexadecyltrimethylammonium acetate, and hexadecyltrimethylammonium nitrate.

24. The device of claim 22, wherein the surfactant provides functional groups that promote the adhesion of the active material particles to the network.

25. The apparatus of claim 1, wherein the cathode active material comprises lithium iron phosphate oxide, and wherein the anode active material comprises a combination of silicon oxide and graphite.

26. The apparatus of claim 25, wherein the silicon oxide is present in an amount of 15 wt% to 25 wt% based on the total weight of the anodic active material.

27. The apparatus of claim 25, wherein the apparatus is free of polyvinylidene fluoride and wherein the slurry used to manufacture the anode active material is free of N-methyl-2-pyrrolidone (NMP).

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