Electrode for energy storage device

Abstract

The invention relates to an electrode for an energy storage device. The disclosed electrode active layer includes a network of high aspect ratio carbon elements (e.g., carbon nanotubes, carbon nanotube bundles, graphene sheets, etc.) that provides a highly conductive scaffold wound or entangled with the active material, thereby supporting the layer. A surface treatment may be applied to the high aspect ratio carbon element to promote adhesion to the active material and any underlying electrode layer, thereby improving overall adhesion and mechanical stability of the active layer. The surface treatment forms only a thin (in some cases even monomolecular) layer on the network, leaving a large void space without any bulk binder material, and thus may alternatively be filled with the active material. The resulting active layer can be formed with excellent mechanical stability even under large thickness and high active material mass loading.

Description

[0001] This patent application is a divisional application of the patent application filed on July 6, 2020, with international application number PCT / US2020 / 040943, application number 202080056350.3 after entering the Chinese national phase, and entitled "Electrode for Energy Storage Device".

[0002] Cross-reference to related applications

[0003] This application claims the benefit and priority of U.S. Provisional Patent Application Serial No. 63 / 041801, filed June 19, 2020; U.S. Provisional Patent Application Serial No. 62 / 954771, filed December 30, 2019; U.S. Provisional Patent Application Serial No. 62 / 871041, filed July 5, 2019; and U.S. Provisional Patent Application Serial No. 63 / 003341, filed April 1, 2020, the entire contents of each of the foregoing references being incorporated herein by reference. Technical Field

[0004] This invention relates to electrodes for energy storage devices. Background Technology

[0005] Lithium-ion batteries are used in a variety of products, including medical devices, electric vehicles, aircraft, and consumer products such as laptops, mobile phones, and cameras. Due to their high energy density, high operating voltage, and low self-discharge, lithium-ion batteries have expanded beyond the secondary battery market and continue to find new applications in products and evolving industries.

[0006] 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 a solvent to form a paste or slurry, which is then coated and dried onto a current collector (such as aluminum or copper) to form a 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.

[0007] In conventional electrodes, the adhesive possesses sufficient adhesiveness and chemical properties to ensure that the film coated on the current collector remains in contact with it even when being manipulated for assembly into a pressurized battery casing. Since this film contains the electrode active materials, failure to maintain adequate contact with the current collector can significantly interfere with the battery's electrochemical performance. Furthermore, it is crucial to select an adhesive that is mechanically compatible with the electrode active materials, enabling it to withstand the expansion and contraction of these materials during battery charging and discharging.

[0008] Therefore, adhesives (such as cellulose adhesives or crosslinked polymer adhesives) have been used to provide good mechanical properties. However, such adhesive materials have adverse effects. For example, most of the adhesive fills the volume in the electrode active layer that would otherwise be used to increase the mass loading of the active material and reduce the conductivity of the electrode. Moreover, the adhesive tends to undergo electrochemical reactions with the electrolyte used in the battery (especially in high-voltage, high-current, and / or high-temperature applications), leading to a deterioration in battery performance. Summary of the Invention

[0009] The applicant has recognized that electrodes can be constructed to exhibit excellent mechanical stability without requiring a large volume of polymer binder. In one aspect, this disclosure describes embodiments of an electrode active layer comprising a network of high aspect ratio carbon elements (e.g., carbon nanotubes, carbon nanotube bundles, graphene sheets, etc.) that provides a highly conductive scaffold for entanglement or winding of the active material, thereby supporting the layer. As detailed below, a surface treatment can be applied to the high aspect ratio carbon elements to promote adhesion to the active material and any underlying electrode layer (e.g., current collector layer), thereby improving the overall adhesion 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 allowing for alternative filling with the active material. Even with large thicknesses and high active material mass loads, the resulting active layer can be formed with excellent mechanical stability.

[0010] On the other hand, this disclosure describes a method comprising: dispersing high aspect ratio carbon elements and surface treatment materials in a solvent to form an initial slurry, wherein the dispersion step results in the formation of a surface treatment 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.

[0011] Various embodiments may include any features or elements described herein, individually or in any suitable combination. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of an electrode characterized by an active material layer.

[0013] Figure 2 This is a detailed illustration of an embodiment of the active material layer.

[0014] Figure 3 This is a detailed illustration of the active material layer in another embodiment.

[0015] Figure 4 These are electron micrographs of the type of active material described in this article.

[0016] Figure 5 This is a schematic diagram of an energy storage battery.

[0017] Figure 6 It shows the manufacturing process. Figure 1 The flowchart shows the method for using electrodes.

[0018] Figure 7 A schematic diagram of a pouch cell is shown.

[0019] Figure 8 A summary of the functional parameters of pouch cells for EV applications is shown.

[0020] Figure 9 A summary of the functional parameters of the pouch battery is shown.

[0021] Figure 10 The results of a comparative performance evaluation of a pouch cell featuring a binderless cathode (left) and a pouch cell featuring a binder-based cathode (right) are shown.

[0022] Figure 11 The results of a comparative performance evaluation of a pouch cell characterized by a binderless cathode (upper trace) and a pouch cell characterized by a binder-based cathode (lower trace) are shown.

[0023] Figure 12 This is a schematic diagram of a half-cell lithium battery device.

[0024] Figure 13 This is a graph showing the potential (reference Li / Li+ potential) versus specific capacity of a binderless cathode half-cell (solid trace) and a reference binder-based cathode half-cell (dashed trace) at different current densities.

[0025] Figure 14 This is a graph showing the potential (reference Li / Li+ potential) versus volumetric capacity of a binderless cathode half-cell (solid trace) and a reference binder-based cathode half-cell (dashed trace) at different current densities.

[0026] Figure 15 The volumetric capacity versus current density is shown for a binderless cathode half-cell (upper trace) and a cathode half-cell based on a reference binder (lower trace).

[0027] Figure 16 Nyquist plots generated from the electrochemical impedance spectroscopy of several binderless cathode half-cells (traces marked with squares, circles, and triangles) and a reference binder-based cathode half-cell are shown. The binderless cathode half-cells exhibit significantly better performance than the reference cell. Detailed Implementation

[0028] refer to Figure 1 The diagram illustrates an electrode 10 including an active layer 100 disposed on a current collector 101. Some embodiments may include an optional adhesion layer 102 disposed between the active layer 101 and the current collector 102. In other embodiments, the adhesion layer 102 may be omitted.

[0029] Current collector 101 may be a conductive layer, such as a metal foil. An optional adhesion layer 102 (which may be omitted in some embodiments) may be a material layer that promotes adhesion between current collector 102 and active layer 100. Examples of suitable materials for current collector 101 and optional adhesion layer 102 are described in International Patent Publication No. WO / 2018 / 102652, published on June 7, 2018.

[0030] Electrode active layer

[0031] In some embodiments, the active layer 100 may include a three-dimensional network 200 of high aspect ratio carbon elements 201, defining 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 wrapped in the network 200, thereby improving the adhesion of the active layer 100.

[0032] 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 The surface treatment promotes adhesion between the high aspect ratio carbon elements and the active material particles 300. The surface treatment also promotes adhesion between the high aspect ratio carbon elements and the current collector 100 (also referred to herein as the “conductive layer”) and / or the optional adhesion layer 102.

[0033] As used in this article, the term "high aspect ratio carbon" refers to a carbon element whose size in one or more dimensions ("primary dimensions") is significantly larger than its size in the horizontal dimension ("secondary dimensions").

[0034] For example, in some embodiments, the high aspect ratio carbon element 201 may include a sheet or plate-like element having two primary dimensions and one secondary dimension. For example, in some such embodiments, the length ratio of each of the primary dimensions 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.

[0035] For example, in some embodiments, the high aspect ratio carbon element 201 may include an elongated rod-like or fibrous element 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.

[0036] 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 curved flakes, and / or formed as high aspect ratio cones, rods, etc.

[0037] In some embodiments, the electrode active layer 100 may contain little or no bulk binder material, thereby leaving more space in the network 200 occupied by the active material particles 300. For example, in some embodiments, the active layer 200 contains less than 10%, less than 1%, less than 0.1%, less than 0.01% or less by weight of binder material (e.g., polymeric or cellulose binder material) disposed in the void spaces.

[0038] For example, in some embodiments, the electrode active layer contains no or substantially no polymeric material or any material other than the active material 300, and the network 200 is composed of high aspect ratio carbon elements 201 and surface treatments 202 disposed thereon.

[0039] In some embodiments, network 200 is primarily or even entirely composed of carbon. For example, in some embodiments, network 200 is at least 90% carbon by weight, at least 95% carbon by weight, at least 96% carbon by weight, at least 97% carbon by weight, at least 98% carbon by weight, at least 99% carbon by weight, at least 99.5% carbon by weight, at least 99.9% carbon by weight, or more.

[0040] In some embodiments, the size (e.g., average size, median size, or minimum size) of the high aspect ratio carbon elements 201 forming the network 200 along one or two major dimensions 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 greater. For example, in some embodiments, the size (e.g., average size, median size, or minimum size) of the elements 201 forming the network 200 can be in the range of 1 μm to 1000 μm, or any subrange thereof (such as 1 μm to 600 μm).

[0041] In some embodiments, the size of the elements can be relatively uniform. For example, in some embodiments, 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 main dimensions.

[0042] The applicant has discovered that an active layer 100 of the type described herein can provide exemplary properties (e.g., high conductivity, low resistance, high voltage performance, and high energy and power density) even when the mass fraction of the elements 201 constituting network 200 in layer 100 is very low, thereby allowing for a high-quality loading of the active material particles 300. 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 the active material particles 300.

[0043] In some embodiments, network 200 forms an interconnect network of highly conductive paths for the transport of current (e.g., electrons or ions) through active layer 100. For example, in some embodiments, highly conductive junctions may appear at points where the elements 201 of the network intersect each other, or at points where they are close enough to allow quantum tunneling of charge carriers (e.g., electrons or ions) 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, in the range of 0.5 wt% to 10 wt% or any subrange thereof, such as 1 wt% to 5.0 wt%), the interconnect network of highly conductive paths formed in network 200 can provide long conductive paths to facilitate the flow of current within and through the active layer 100 (e.g., conductive paths on the order of the thickness of active layer 100).

[0044] For example, in some embodiments, network 200 may include one or more structures of interconnect elements 201, wherein the total length of the structure along one or more dimensions is 2, 3, 4, 5, 10, 20, 50, 100, 500, 1,000, 10,000 or more times the average length of the constituent elements 201 constituting the structure. For example, in some embodiments, network 200 may include one or more structures of interconnect elements 200, wherein the total length of the structure is 2 to 10,000 times (or any subrange thereof) the average length of the constituent elements 201 constituting the structure. For example, in some embodiments, network 200 may include highly conductive paths with lengths greater than 100 μm, 500 μm, 1,000 μm, 10,000 μm or larger (e.g., in the range of 100 μm to 10,000 μm in any of its subranges).

[0045] As used herein, the term “highly conductive path” should be understood as a path formed by interconnect element 201, which has a higher conductivity than the active material particles embedded in network 200.

[0046] To avoid being bound by theory, in some embodiments, network 200 can be characterized as an electrically interconnected network of elements 201 exhibiting connectivity exceeding a percolation threshold. The percolation threshold is a mathematical concept related to percolation theory, which describes the form of long-range connectivity in a stochastic system. Below the threshold, there are no so-called "giant" connections on the order of the system size; above the threshold, giant connections on the order of the system size exist.

[0047] In some embodiments, the percolation threshold can be determined by increasing the mass fraction of element 201 in the active layer 100 while measuring the conductivity of the layer, while keeping all other properties of the layer constant. In some such cases, the threshold can be identified by the mass fraction of the layer whose conductivity increases sharply and / or the mass fraction of the layer whose conductivity increases slowly only with the addition of more element 201. Such behavior indicates the threshold required to form interconnect structures that provide conductive paths with lengths on the order of the size of the active layer 100.

[0048] Figure 2 A network 200 (e.g., located near several active material particles 300) is shown. Figure 1 A detailed view of a high aspect ratio carbon element 201 is 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 having a hydrophobic end 211 and a hydrophilic end 212, wherein the hydrophobic end is disposed near the surface of carbon element 201 and the hydrophilic end 212 is disposed far from the surface.

[0049] In some embodiments where carbon element 201 is hydrophobic (such as the typical case of nano-shaped carbon elements, 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 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 the electrostatic interaction between elements 201 and 210 within the slurry.

[0050] In some embodiments, the 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 region of the surface of element 201 is covered with surfactant element 210, additional surfactant elements 210 will not be attracted to that region. In some embodiments, once the surface of element 201 is covered with surfactant element 202, other elements are repelled from the layer, resulting in a self-confining process. For example, in some embodiments, the surface treatment 202 may be formed during the self-confining process, thereby ensuring that the layer is thin, such as a single molecule or a few molecules thick.

[0051] In some embodiments, at least a portion of the hydrophilic ends 212 of the surfactant elements form bonds with the active material particles 300. Therefore, the surface treatment 202 can provide good adhesion between the elements 201 of the network 200 and the active material particles. In some embodiments, the bonds can be covalent or non-covalent, such as π-π bonds, hydrogen bonds, electrostatic bonds, or combinations thereof.

[0052] For example, in some embodiments, the hydrophilic end 212 of the surfactant element 210 has a first polarity of polar charge, while the surface of the active material particles 300 carries a second polarity of polar charge opposite to the first polarity of polar charge, and thus they attract each other.

[0053] For example, in some embodiments, during the formation of layer 100, the active material particles 300 are bonded in a solvent to the carbon elements 201 carrying the surface treatment 202 (as described in more detail below), and the outer surface of the active material particles 300 can be characterized by a zeta potential having a sign opposite to that of the outer surface of the surface treatment 202 (as is known in the art). Therefore, in some such embodiments, the attractive force between the carbon elements 201 carrying the surface treatment 202 and the active material product 300 facilitates the self-assembly of the structure, wherein the active material particles 300 are entangled with the carbon elements 201 of the network 200.

[0054] In some embodiments, at least a portion of the hydrophilic ends 212 of the surfactant elements form bonds with the current collector layer or adhesion layer beneath the active material layer 100. Therefore, the surface treatment 202 can provide good adhesion between the elements 201 of the network 200 and such underlying layers. In some embodiments, the bonds can be covalent or non-covalent, such as π-π bonds, hydrogen bonds, electrostatic bonds, or combinations thereof. In some embodiments, this arrangement provides excellent mechanical stability for the electrode 10, as discussed in more detail below.

[0055] In various embodiments, the surfactant used to form the surface treatment 202 as described above may include any suitable material. For example, in some embodiments, the surfactant may include one or more of the following: hexadecyltrimethylammonium hexafluorophosphate (CTAP), hexadecyltrimethylammonium tetrafluoroborate (CTAB), hexadecyltrimethylammonium acetate, hexadecyltrimethylammonium nitrate, cocamidopropyl betaine, N-(cocarboxy)-N,N,N-trimethylmethylammonium sulfate, and cocamidopropyl betaine. Other suitable materials are described below.

[0056] In some embodiments, the surfactant layer 202 can be formed by dissolving a compound in a solvent such that the surfactant layer is formed from ions from the compound (e.g., in a self-confining 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.

[0057] In some embodiments, these surfactant counterions 214 are selected to be compatible with use in electrochemical batteries. For example, in some embodiments, the counterions are selected to not react or react mildly with materials used in the battery, such as electrolytes, separators, casings, etc. For example, if an aluminum casing is used, the counterions may be selected to not react with the aluminum casing or react mildly with the aluminum casing.

[0058] For example, in some embodiments, the residual counter ion contains no or substantially no halogen groups. For example, in some embodiments, the residual counter ion contains no or substantially no bromine.

[0059] In some embodiments, the residual counterions can be selected to be compatible with the electrolyte used in the energy storage battery comprising the active layer 200. For example, in some embodiments, the residual counterions can be the same kind of ions used in the electrolyte itself. For example, if the electrolyte comprises a dissolved Li PF6 salt, the electrolyte anion is PF6. In such cases, the surfactant can be selected as, for example, CTA PF6, such that the surface treatment 202 is formed as an anionic layer from CTA PF6, and the residual surfactant counterions are PF6 anions from CTA PF6 (thus matching the electrolyte anions).

[0060] 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 solvent properties, such as low-boiling-point additives, such as acetonitrile (ACN), deionized water, and tetrahydrofuran.

[0061] For example, if a low-boiling-point solvent is used in the formation of the surface-treated material 202, the solvent can be quickly removed using a thermal drying process performed at a relatively low temperature (e.g., 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.

[0062] For example, in some embodiments, the surface treatment 202 is formed of a material that is soluble in a solvent with 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.

[0063] 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, toxicity comparable to that of alcohols such as isopropanol.

[0064] It is noteworthy that this contrasts with processes used to form conventional electrode active layers, which are characterized by bulky binder materials such as polyvinylidene fluoride or polyvinylidene fluoride (PVDF). Such bulky binders require corrosive solvents, typically characterized by high boiling points. One such example is n-methyl-2-pyrrolidone (NMP). Using NMP (or other pyrrolidone-based solvents) as a solvent requires a high-temperature drying process to remove the solvent. Moreover, NMP is expensive, requires complex solvent recovery systems, and is highly toxic, posing serious safety concerns. Conversely, 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.

[0065] While an exemplary surface treatment 202 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. Functional groups selectively applied to element 201 may be used to promote adhesion between the active material particles 300 and the network 200. For example, in various embodiments, the functional groups may include carboxyl groups, hydroxyl groups, amino groups, silyl groups, or combinations thereof.

[0066] 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 nano-shaped carbon and functionalized 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.

[0067] refer to Figure 3In some embodiments, the surface treatment 202 on the high aspect ratio carbon element 201 includes a thin polymer layer disposed on the carbon element, which promotes adhesion of the active material to the network. In some such embodiments, the thin polymer layer includes a self-assembled and / or self-confined polymer layer. In some embodiments, the thin polymer layer is bonded to the active material, for example, via hydrogen bonding.

[0068] In some embodiments, the thin polymer layer may have a thickness of 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.

[0069] In some embodiments, the thin polymer layer includes functional groups (e.g., side functional groups) that are bonded to the active material via non-covalent bonds (such as π-π bonds). In some such embodiments, the thin polymer layer may form a stable capping layer on at least a portion of element 201.

[0070] In some embodiments, a thin polymer layer on some 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 side functional groups bonded to the surface of the current collector 101 or the adhesion layer 102, 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 on at least a portion of element 201. In some embodiments, this arrangement provides excellent mechanical stability of the electrode 10, as discussed in more detail below.

[0071] In some embodiments, the polymeric material may be miscible in solvents of the types described in the examples above. For example, in some embodiments, the polymeric material may be 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 solvent properties, such as low-boiling-point additives, such as acetonitrile (ACN), deionized water, and tetrahydrofuran.

[0072] 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.

[0073] In some embodiments, the polymeric 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 lower.

[0074] Note that the thin polymer layer described above differs in nature from the bulk polymer binder used in conventional electrodes. Instead of filling most of the volume of the active layer 100, the thin polymer layer resides on the surface of the high aspect ratio carbon elements, thus leaving the majority of the void space within the network 200 available to accommodate the active material particles 300.

[0075] For example, in some embodiments, the thin polymer layer has a maximum thickness less than or equal to 1, 0.5, 0.25, or less than the size of carbon element 201 along its secondary dimension in the 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). Therefore, 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 using the thin polymer layer.

[0076] In yet another exemplary embodiment, the surface treatment 202 may be formed of a carbonaceous material layer produced by the pyrolysis of a polymeric material disposed on high aspect ratio carbon elements 201. This carbonaceous material layer (e.g., graphite or amorphous carbon) may adhere (e.g., via covalent bonds) to the active material particles 300 or otherwise promote adhesion to the active material particles. 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 use in this technique is polyacrylonitrile (PAN).

[0077] In various embodiments, the active material particles 300 may include any active material suitable for use in energy storage devices, including metal oxides such as lithium metal oxides. For example, the active material particles 300 may include lithium cobalt oxide (LCO, sometimes called "lithium cobaltate" or "lithium cobaltite"), a chemical compound with one possible variant of the chemical formula LiCoO2; lithium nickel manganese cobalt oxide (NMC, with variants LiNiMnCo); lithium manganese oxide (LMO, with variants LiMn2O4, Li2MnO3, and others); lithium nickel cobalt aluminum oxide (LiNiCoAlO2 and its variants such as NCA); and lithium titanate oxide (LTO, one variant of which is Li4Ti5O). 12 ); lithium iron phosphate oxide (LFP, one variant of which is LiFePO4), lithium nickel cobalt aluminum oxide (and its variants such as NCA), and other similar materials. Other variants of the foregoing may be included.

[0078] In some embodiments where NMC is used as the active material, nickel-rich NMC can be used. 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 foregoing formula, x is about 0.8 and y is about 0.1.

[0079] In some embodiments, the active material includes other forms of lithium nickel manganese cobalt oxide (LiNi). x Mn y Co2O2). For example, common variants include, but are not limited to: NMC111(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 other variants can be used.

[0080] In some embodiments, such as when the electrode is used as an anode, the active material may include graphite, hard carbon, activated carbon, carbon nanoparticles, silicon, silicon oxide, or carbon-encapsulated silicon nanoparticles. In some such embodiments, the active layer 100 may be intercalated with lithium, for example, using pre-lithiation methods known in the art.

[0081] In some embodiments, the techniques described herein can allow the active layer 100 to be made of a majority of the material in the active layer, for example, greater than 75%, 80%, 85%, 90%, 95%, 99%, 99.5%, 99.8% or more by weight, 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 more), while still exhibiting excellent mechanical properties (e.g., no delamination during operation in an energy storage device of the type described herein).

[0082] The active material particles 201 in the active layer 100 may be characterized by median particle sizes in the range of, for example, 0.1 μm and 50 μm, or any subrange thereof. The active material particles 201 in the active layer 100 may be characterized by a unimodal, bimodal, or multimodal particle size distribution. The active material particles 201 may have a particle size distribution of 0.1 m² / g (m² / g). 2 / g) and 100 square meters per gram (m 2 Specific surface area within the range of / g or any subrange thereof.

[0083] In some embodiments, the active layer 100 may have, for example, at least 20 mg / cm³. 2 30 mg / cm 2 40 mg / cm 2 50 mg / cm 2 60 mg / cm 2 70 mg / cm 2 80 mg / cm 2 90 mg / cm 2 100 mg / cm 2 Or a mass loading of 300 or larger active material particles.

[0084] refer to Figure 4 An electron micrograph of an exemplary active material layer of the type described herein is shown. Tendril-like high aspect ratio carbon elements 201 (formed from CNT bundles) are clearly shown as entangled active material particles 300. Note that there is no bulk polymeric material occupying the space within this layer.

[0085] Energy storage battery

[0086] refer to Figure 5 The diagram illustrates an energy storage battery 500, which includes a first electrode 501, a second electrode 502, a permeable separator 503 disposed between the first electrode 501 and the second electrode 502, and an electrolyte 504 that wets the first and second electrodes. One or both of the electrodes 501 and 502 may be of the type described herein.

[0087] In some embodiments, the energy storage battery 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, such as the type of lithium salt described in Qi Li, Juner Chen, Lei Fan, Xueqian Kong, and 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.

[0088] In some such embodiments, the energy storage battery may have an operating voltage in the range of 1.0 V to 5.0 V or any subrange thereof, such as 2.3 V to 4.3 V.

[0089] In some such embodiments, the energy storage battery 500 may have an operating temperature range including -40°C to 100°C or any subrange thereof, such as -10°C to 60°C.

[0090] In some such embodiments, the energy storage battery 500 may have a gravimetric energy density of at least 100 Wh / kg, 200 Wh / kg, 300 Wh / kg, 400 Wh / kg, 500 Wh / kg, 1000 Wh / kg or higher.

[0091] In some such embodiments, the energy storage battery 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.

[0092] In some such embodiments, the energy storage battery 500 may have a C rate in the range of 0.1 to 50.

[0093] In some such embodiments, the energy storage battery 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.

[0094] In some embodiments, the energy storage battery 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.

[0095] In some such embodiments, the energy storage battery 500 may have an operating temperature range including -60°C to 100°C or any subrange thereof, such as -40°C to 85°C.

[0096] In some such embodiments, the energy storage battery 500 may have a weight energy density of at least 10 Wh / kg, 15 Wh / kg, 20 Wh / kg, 30 Wh / kg, 40 Wh / kg, 50 Wh / kg or higher.

[0097] In some such embodiments, the energy storage battery 500 may have a volumetric energy density of at least 20 Wh / L, 30 Wh / L, 40 Wh / L, 50 Wh / L, 60 Wh / L, 70 Wh / L, 80 Wh / L or higher.

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

[0099] In some such embodiments, the energy storage battery 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.

[0100] In some such embodiments, the energy storage battery 500 may have a C rate in the range of 1.0 to 100.

[0101] In some such embodiments, the energy storage battery 500 may have a cycle life of at least 100,000, 500,000, 1,000,000 or more charge-discharge cycles.

[0102] Manufacturing method

[0103] The electrode 10, characterized by the active layer 100 described herein, can be manufactured using any suitable manufacturing process. As those skilled in the art will understand, in some embodiments, and further in light of the teachings described herein, 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.

[0104] refer to Figure 6In some embodiments, the active layer 100 of electrode 10 may be formed using method 1000. In step 1001, high aspect ratio carbon element 201 and surface treatment material (e.g., surfactants or polymeric materials described herein) are combined with a solvent (solvents of the type described herein) to form an initial slurry.

[0105] In step 1002, the initial slurry is treated to ensure good dispersion of the solid material within the slurry. In some embodiments, this treatment includes introducing mechanical energy into the mixture of solvent and solid material (e.g., using an ultrasonic generator, which is sometimes also referred to as an "ultrasonic crusher") or other suitable mixing equipment (e.g., a high-shear mixer). In some embodiments, the mechanical energy introduced into the mixture is at least 0.4 kWh / kg, 0.5 kWh / kg, 0.6 kWh / kg, 0.7 kWh / kg, 0.8 kWh / kg, 0.9 kWh / kg, 1.0 kWh / kg, or more. For example, the mechanical energy introduced into the mixture per kilogram of mixture can be in the range of 0.4 kWh / kg to 1.0 kWh / kg or any subrange thereof, such as 0.4 kWh / kg to 0.6 kWh / kg.

[0106] In some embodiments, an ultrasonic bath mixer may be used. In other embodiments, a probe ultrasonic generator may be used. Probe ultrasonication can be significantly more powerful and efficient than ultrasonic baths used for nanoparticle applications. The high shear forces generated by ultrasonic cavitation have the ability to break up particle agglomerates and result in smaller and more uniform particle sizes. Among other things, ultrasonication can result in a stable and homogeneous suspension of solids in a slurry. Typically, this leads to dispersion, deagglomeration, and other decomposition of solids. Examples of probe ultrasonication devices include the Q-series probe ultrasonic generator, available from QSonica LLC, Newtown, Connecticut. Another example includes the Branson Digital SFX-450 ultrasonic generator, commercially available from Thomas Scientific, Switzboro, New Jersey.

[0107] However, in some embodiments, the local properties 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 overcome by using a setup with continuous flow units and proper mixing. That is, with such a setup, the slurry will be mixed to achieve reasonably uniform dispersion.

[0108] In some embodiments, the initial slurry, once processed, 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.

[0109] In step 1003, the surface treatment 202 may be formed entirely or partially on the high aspect ratio carbon elements 201 in the initial slurry. In some embodiments, at this stage, the surface treatment 202 may be as referenced above. Figure 2 and Figure 3 As described in the detailed description, it self-assembles. The resulting surface treatment 201 may include functional groups or other features that, as described in the following additional steps, can promote adhesion between the high aspect ratio carbon element 201 and the active material particles 300.

[0110] In step 1004, the active material particles 300 may be combined with the initial slurry to form a final slurry, which includes the active material particles 300 and high aspect ratio carbon elements 201 on which surface treatment 202 is formed.

[0111] In some embodiments, the active material 300 may be added directly to the initial slurry. In other embodiments, the active material 300 may first be dispersed in a solvent (e.g., using the techniques described above regarding the initial solvent) to form an active material slurry. This active material slurry may then be combined with the initial slurry to form a final slurry.

[0112] In step 1005, the final slurry is treated to ensure good dispersion of the solid material 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 reference to step 1002. In some embodiments, a planetary mixer, such as a multi-axis (e.g., triaxial or multi-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 disk dispersing blades.

[0113] In some embodiments, during step 1005, the matrix 200 of the entangled active material 300 may be fully or partially self-assembled, as referenced above. Figure 2 and Figure 3 As described in detail. In some embodiments, the interaction between the surface treatment 202 and the active material 300 facilitates the self-assembly process.

[0114] In some embodiments, the final slurry, once processed, 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.

[0115] In step 1006, the active layer 100 is formed from the final slurry. In some embodiments, the final slurry may be directly wet-cast onto the current collector conductive layer 101 (or optionally the adhesion layer 102) and dried. For example, casting can be performed by applying at least one of heat and vacuum until substantially all solvent and any other liquid is 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, it may be desirable to protect the underside of the conductive layer 101, where the electrode 10 is intended for bilateral operation. Protection may include, for example, shielding certain areas from solvents or providing drainage channels to guide the solvent away.

[0116] In other embodiments, the final slurry may be at least partially dried elsewhere and then transferred to the adhesion layer 102 or conductive layer 101 using any suitable technique (e.g., roll-to-roll coating) to form the active layer 100. In some embodiments, a wet-combination slurry may be placed onto an intermediate material having a suitable surface and dried to form the layer (i.e., the active layer 100). While any material with a suitable surface can be used as the intermediate material, exemplary intermediate materials include PTFE, as its properties facilitate subsequent removal from the surface. In some embodiments, the specified layer is formed in a press to provide a layer exhibiting the desired thickness, area, and density.

[0117] In some embodiments, the final slurry can be formed into a sheet and suitably coated onto the adhesion layer 102 or the conductive layer 101. For example, in some embodiments, the final slurry can be applied using a stencil to control the thickness of the applied layer. In other embodiments, the slurry can be applied and then leveled to the desired thickness, for example, using a doctor blade. A variety of other techniques can be used to apply the slurry. For example, coating techniques may include, but are not limited to: comma coating; comma reverse coating; doctor blade coating; stencil coating; direct gravure coating; air doctor blade coating (air knife); indoor doctor blade coating; offset gravure coating; one-roll matching coating; reverse matching coating using a small-diameter gravure roller; bar coating; three-roll reverse coating (top feed); three-roll reverse coating (injection die); reverse roller coating and others.

[0118] The final viscosity of the slurry can vary depending on the application technique. For example, for a comma coating, the viscosity can range from about 1,000 cps to about 200,000 cps. Lip molding coating provides a coating using a slurry exhibiting a viscosity from about 500 cps to about 300,000 cps. Anti-matching coating provides a coating using a slurry exhibiting a viscosity from about 5 cps to 1,000 cps. In some applications, the corresponding layers can be formed in multiple passes.

[0119] In some embodiments, the active layer 100 formed from the final slurry may be compressed (e.g., using a calendering apparatus) before or after being applied 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 less than 90%, 80%, 70%, 50%, 40%, 30%, 20%, 10% or less of its uncompressed thickness (e.g., in the direction normal to the current collector layer 101).

[0120] 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 of the solvent is removed from the active layer 100.

[0121] In some embodiments, the solvent used to form the slurry is recovered and recycled back into the slurry manufacturing process.

[0122] In some embodiments, the active layer may be compressed, for example, to break up a portion of the high aspect ratio carbon elements or other carbonaceous materials, thereby increasing the surface area of ​​the respective layer. In some embodiments, this compression treatment may increase one or more of the following: interlayer adhesion, intralayer ion transport rate, and layer surface area. In various embodiments, compression may be applied before or after the respective layer is applied to or formed on the electrode 10.

[0123] In some embodiments where calendering is used to compress the active layer 100, the calendering apparatus may be configured to have a gap spacing equal to or less than 90%, 80%, 70%, 50%, 40%, 30%, 20%, 10% or less of the layer's pre-compression thickness (e.g., set to about 33% of the layer's pre-compression thickness). 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 in a temperature 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.

[0124] Once the electrode 10 is assembled, the electrode 100 can be used to assemble the energy storage device 10. The assembly of the energy storage device 10 can follow conventional steps for assembling the electrode with the separator and placing it in a housing such as a tank or bag, and may also include additional steps for adding electrolyte and sealing the housing.

[0125] In various embodiments, process 1000 may include any one of the following features (alone or in any suitable combination).

[0126] In some embodiments, the initial slurry has a solids content in the range of 0.1% to 20.0% (or any subrange thereof) by weight. In some embodiments, the final slurry has a solids content in the range of 10.0% to 80% (or any subrange thereof) by weight.

[0127] In various embodiments, the solvent used can be any of those solvents 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 solvent properties, such as low-boiling-point additives, such as acetonitrile (ACN), deionized water, and tetrahydrofuran.

[0128] 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.

[0129] 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, toxicity comparable to that of alcohols such as isopropanol.

[0130] In some embodiments, during the formation of the active layer, the material forming the surface treatment may be dissolved in a solvent that is substantially free of pyrrolidone compounds. In some embodiments, the solvent is substantially free of n-methyl-2-pyrrolidone.

[0131] In some embodiments, the surface treatment 201 is formed of a material comprising surfactants of the type described herein.

[0132] In some embodiments, dispersing high aspect ratio carbon elements and surface treatment materials in a solvent to form an initial slurry involves applying a force to the aggregated carbon elements to cause them to slide apart from each other along a direction transverse to their short axes. In some embodiments, in view of the teachings described herein, techniques for forming such dispersions can be adapted to those disclosed in International Patent Publication No. WO / 2018 / 102652, published on June 7, 2018.

[0133] In some embodiments, the high aspect ratio carbon element 201 may 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; drying the initial slurry to remove substantially all moisture, thereby obtaining a dry powder of high aspect ratio carbon having the surface treatment thereon. In some embodiments, the dry powder may be combined with a slurry, for example, a solvent and an active material, to form a final solvent of the type described above with reference to method 1000.

[0134] In some embodiments, the dried initial slurry includes a lyophilized (freeze-dried) initial slurry. In some embodiments, the aqueous solvent and the initial slurry are substantially free of substances that would impair 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, a surface treatment material, and water.

[0135] Some embodiments further include dispersing a dry powder of high aspect ratio carbon with a surface treatment in a solvent and adding an active material to form a second slurry; coating the second slurry onto a substrate; and drying the second slurry to form an electrode active layer. In some embodiments, in view of the teachings described herein, the foregoing steps may be performed using techniques disclosed in International Patent Publication No. WO / 2018 / 102652, published on June 7, 2018.

[0136] In some embodiments, the final slurry may include polymeric additives such as polyacrylic acid (PAA), polyvinyl alcohol (PVA), polyvinyl 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 a heat-pyrolyzing additive, such that the surface treatment 202 can form a carbonaceous material layer produced by the pyrolysis of the polymeric additive. This carbonaceous material layer (e.g., graphite or amorphous carbon) may adhere (e.g., via covalent bonds) to the active material particles 300 or otherwise promote adhesion to the active material particles. The heat treatment may be performed 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.

[0137] surfactants

[0138] The aforementioned techniques include using surfactants to form a surface treatment 202 on high aspect ratio carbon nanotubes 201 to promote adhesion to the active material particles 300. While several advantageously suitable surfactants have been described, it should be understood that other surfactant materials can be used, including the following.

[0139] Surfactants are molecules or groups of molecules that have surface activity, including wetting agents, dispersants, emulsifiers, detergents, and foaming agents. A variety of surfactants can be used to prepare the surface-treated products described herein. Typically, the surfactants used contain lipophilic nonpolar hydrocarbon groups and polar functional hydrophilic groups. The polar functional group can be a carboxylic acid ester, ester, amine, amide, imide, hydroxyl group, ether, nitrile, phosphate, sulfate, or sulfonate. Surfactants can be used alone or in combination. Therefore, combinations of surfactants can include anionic, cationic, nonionic, zwitterionic, amphoteric, and amphoteric surfactants, provided that a net positive or net negative charge is present in the head region of the group of surfactant molecules. In some cases, a single negatively or positively charged surfactant is used in the preparation of this electrode composition.

[0140] The surfactants used to prepare this electrode composition may 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; phosphate esters; and carboxylates such as fatty acids, alkylalkoxycarboxylates, sarcosine salts, hydroxyethyl sulfonates, and taurine salts. Specific examples of carboxylates are sodium oleate, sodium cocoyl hydroxyethyl sulfonate, sodium methyl oleoyl taurate, sodium lauryl polyoxyethylene ether carboxylate, sodium tridecyl carboxylate, sodium dodecyl sarcosinate, lauroyl sarcosinate, and cocoyl sarcosinate. Specific examples of sulfates include sodium dodecyl sulfate (SDS), sodium lauryl sulfate, sodium lauryl ether sulfate, sodium tridecyl sulfate, sodium cocoyl sulfate, and sodium monoglyceride sulfate.

[0141] 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 2 to 20 carbons and can also be ethoxylated to have up to about 8 units of ethylene oxide, preferably up to about 6 units, with an average of, for example, 2, 3, or 4 units of ethylene oxide. Illustrative examples of alkyl and aryl sulfonates are sodium tridecylbenzenesulfonate (STBS) and sodium dodecylbenzenesulfonate (SDBS).

[0142] Illustrative examples of sulfosuccinates include, but are not limited to, polydimethylsiloxane copolyol sulfosuccinate, dipentyl sulfosuccinate, didecyl sulfosuccinate, dicyclohexyl sulfosuccinate, diheptyl sulfosuccinate, dihexyl sulfosuccinate, diisobutyl sulfosuccinate, dioctyl sulfosuccinate, C12-15 parental sulfosuccinate, cetyl sulfosuccinate, cocoyl polydextrose sulfosuccinate, cocoyl butyl glucose polyether-10 sulfosuccinate, decanol polyether-5 sulfosuccinate, decanol polyether-6 sulfosuccinate, thiodiethylene glycol sulfosuccinoyl undecylene salt, hydrogenated cottonseed glyceryl ester sulfosuccinate, isodecanyl sulfosuccinate, and isostearyl sulfosuccinate. Sulfates, lanolin alcohol polyether-5 sulfosuccinate, lauryl ether sulfosuccinate, lauryl ether-12 sulfosuccinate, lauryl ether-6 sulfosuccinate, lauryl ether-9 sulfosuccinate, dodecyl sulfosuccinate, nonyl alcohol ether-10 sulfosuccinate, oleyl alcohol polyether-3 sulfosuccinate, oleyl alcohol polyether sulfosuccinate, PEG-10 lauryl citrate sulfosuccinate, sitosereth-14 sulfosuccinate, stearoyl sulfosuccinate, tallow, tridecyl sulfosuccinate, ditridecyl sulfosuccinate, diethylene glycol castor sulfosuccinate, bis(1,3-bis-methylbutyl) sulfosuccinate, and silicone copolyol sulfosuccinate.

[0143] Illustrative examples of sulfosuccinates include, but are not limited to, lauramide-MEA sulfosuccinate, oleamide-PEG-2 sulfosuccinate, cocamidoyl MIPA-sulfosuccinate, cocamidoyl 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-P... EG-2 sulfosuccinate, palmamide-based PEG-2 sulfosuccinate, palm oleamide-based PEG-2 sulfosuccinate, PEG-4 cocoamide MIPA-sulfosuccinate, castoramide-based MEA-sulfosuccinate, stearamide MEA-sulfosuccinate, stearyl sulfosuccinate, tallow oleamide MEA-sulfosuccinate, tallow oleamide MEA-sulfosuccinate, undecyleneamide MEA-sulfosuccinate, undecyleneamide PEG-2 sulfosuccinate, wheat germ oleamide MEA-sulfosuccinate, and wheat germ oleamide PEG-2 sulfosuccinate.

[0144] 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., Westhill, Ontario, Canada). AEROSOL® OT-S is sodium dioctyl sulfosuccinate in a petroleum fraction. AEROSOL® OT-MSO also contains sodium dioctyl sulfosuccinate. AEROSOL® TR70% is sodium ditridecyl sulfosuccinate in a mixture of ethanol and water. NaSul CA-HT3 is a calcium nonylnaphthalene sulfonate / calcium carboxylate complex. C500 is an oil-soluble calcium sulfonate.

[0145] Alkyl or alkyl groups refer to saturated hydrocarbons having one or more carbon atoms, including straight-chain alkyl groups (e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, etc.), cyclic alkyl groups (or cycloalkyl, alicyclic, or carbocyclic groups) (e.g., cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, etc.), branched alkyl groups (e.g., isopropyl, tert-butyl, sec-butyl, isobutyl, etc.), and alkyl-substituted alkyl groups (e.g., alkyl-substituted cycloalkyl groups and cycloalkyl-substituted alkyl groups).

[0146] Alkyl groups can include unsubstituted alkyl groups and substituted alkyl groups. A substituted alkyl group is an alkyl group having a substituent that replaces one or more hydrogen atoms on one or more carbons of the hydrocarbon backbone. Such substituents may include alkenyl, alkynyl, halogen, hydroxyl, alkyl carbonyloxy, aryl carbonyloxy, alkoxy carbonyloxy, aryloxy, aryloxy carbonyloxy, carboxyl, alkyl carbonyl, aryl carbonyl, alkoxy carbonyl, amino carbonyl, alkyl amino carbonyl, dialkyl amino carbonyl, alkyl thioamino, alkoxy, phosphate, phosphonoyl, phosphonite, cyano, amino (including alkylamino, dialkylamino, arylamino, diarylamino and alkylarylamino), acylamino (including alkyl carbonylamino, aryl carbonylamino, carbamoyl and urea), imino, mercapto, alkylthio, arylthio, thiocarboxylic acid ester, sulfate, alkyl sulfinyl, sulfonate, sulfonyl, sulfonamide, nitro, trifluoromethyl, cyano, azide, heterocyclic, alkyl acyl or aromatic (including heteroaromatic) groups.

[0147] In some embodiments, the substituted alkyl group may include a heterocyclic group. The heterocyclic group includes a closed-ring structure similar to a carbocyclic group, wherein one or more of the 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 aziridine, ethylene oxide (epoxide, ethylene oxide), cyclothioethane (cyclosulfide), dicyclothioethane, aziridine, oxobutane, thiobutane, dioxobutane, dithiobutane, dithiocyclobutene, pyrrolidine, tetrahydropyrrole, pyrrololine, oxopentane, dihydrofuran, and furan.

[0148] For anionic surfactants, the counterion is typically sodium, but can alternatively be potassium, lithium, calcium, magnesium, ammonium, amines (primary, secondary, tertiary, or quaternary), or other organic bases. Exemplary amines include isopropylamine, ethanolamine, diethanolamine, and triethanolamine. Mixtures of the above-mentioned cations can also be used.

[0149] The surfactant used to prepare the materials of this invention can be cationic. Such cationic surfactants include, but are not limited to, compounds containing pyridinium, and primary, secondary, tertiary, or quaternary organic amines. For cationic surfactants, counterions can be, for example, chlorides, bromides, methyl sulfate, glycol sulfate, lactate, saccharin, acetate, and phosphate. Examples of cationic amines include polyethoxylated oleyl alcohol / stearyl amine, ethoxylated tallow amine, cocoyl alkyl amine, oleyl amine, and tallow alkyl amine, and mixtures thereof.

[0150] Examples of quaternary ammonium compounds having a single long alkyl group are hexadecyltrimethylammonium bromide (CTAB), benzyldodecyldimethylammonium bromide (BddaBr), benzyldimethylhexadecylammonium chloride (BdhaCl), dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, stearyldimethylbenzylammonium chloride, oleyldimethylbenzylammonium chloride, dodecyltrimethylmethylammonium sulfate (also known as cocoyl methyl hydrogen sulfate), hexadecyl-dimethylhydroxyethyl dihydrogen phosphate, and palm oil. Aminopropyl dimethyl benzyl ammonium chloride, cocoyl trimethyl ammonium chloride, dioctadecyl dimethyl ammonium chloride, maltopropyl dimethyl benzyl ammonium chloride, methyl sulfate octadecyl octyl dimethyl ammonium, isooctadecylaminopropyl dimethyl benzyl ammonium chloride, dihydroxypropyl PEG-5 linseed oil methyl ammonium chloride, PEG-2 octadecyl dimethyl ammonium chloride, benzyl trimethyl ammonium chloride, dihexadecyl dimethyl ammonium chloride, tallow-based trimethyl ammonium chloride, and ethyl sulfate benzylaminopropyl ethyl dimethyl ammonium.

[0151] Examples of quaternary ammonium compounds having two long alkyl groups are bis(dodecyl)dimethylammonium bromide (DDAB), distearyldimethylammonium chloride, bis(hexadecyl)dimethylammonium chloride, stearyloctyldimethylmethoxysulfate, palmityl ethyl hydroxyethyl methylammonium sulfate, palmitoyl methyl methyl methyl ammonium sulfate, dipalmitoyl ethyl hydroxyethyl methyl ammonium sulfate, and hydroxypropyl bis(octadecyl)dimethylammonium chloride.

[0152] Quaternary ammonium compounds of imidazoline derivatives include, for example, isooctadecylbenzylimidazoline hydrochloride, cocoylbenzylhydroxyethylimidazoline hydrochloride, cocoylhydroxyethylimidazoline PG-hydrochloride phosphate, and octadecylhydroxyethylimidazoline hydrochloride. Other heterocyclic quaternary ammonium compounds, such as dodecylpyridine chloride, aminopropylline hydrochloride (AH), and benzyl chloride (BH), may also be used.

[0153] The surfactants used to prepare the materials of this invention can be nonionic, including but not limited to polyepoxyalkylene carboxylates, fatty acid esters, fatty alcohols, ethoxylated fatty alcohols, poloxamers, alkanolamides, alkoxylated alkanolamides, polyethylene glycol monoalkyl ethers, and alkyl polysaccharides. Polyepoxyalkylene carboxylates have one or two carboxyl ester moieties each having about 8 to 20 carbons and a polyoxyalkylene moieties comprising about 5 to 200 alkylene oxide units. Ethoxylated fatty alcohols comprise an ethylene oxide moieties containing about 5 to 150 ethylene oxide units and a fatty alcohol moieties having about 6 to about 30 carbons. The fatty alcohol moieties can be cyclic, linear, or branched, saturated or unsaturated. Some examples of ethoxylated fatty alcohols include oleyl alcohol, stearyl alcohol, lauryl alcohol, and ethylene glycol ethers of isoacetyl alcohol. Poloxamers are ethylene oxide and propylene oxide block copolymers having about 15 to about 100 moles of ethylene oxide. Alkyl polysaccharide (“APS”) surfactants (such as alkyl polyglycosides) comprise a hydrophobic group having about 6 to about 30 carbons and a polysaccharide (such as a polyglycoside) as a hydrophilic group. An example of a commercially available nonionic surfactant is FOA-5 (Octel Starreon LLC, Littleton, Colorado).

[0154] 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, cocamidoamine oxide, cocamidopropylamine oxide, and laurylaminepropylamine oxide; sorbitan laurate, sorbitan distearate, fatty acids, or fatty acid esters, such as lauric acid, isostearic acid, and PEG-150 distearate; fatty alcohols or ethoxylated fatty alcohols, such as lauryl alcohol; and alkyl polysaccharides, such as alkyl glucoside, lauryl glucoside, and cocoyl glucoside.

[0155] The surfactant used to prepare the materials of this invention can be zwitterionic, having both a positive and a negative charge on the same molecule. The positively charged group can be quaternary ammonium, phosphorus, or sulfonium, while the negatively charged group can be carboxylate, sulfonate, sulfate, phosphate, or phosphonate. Similar to other types of surfactants, the hydrophobic portion can contain one or more long, straight, cyclic, or branched aliphatic chains of about 8 to 18 carbon atoms. Specific examples of zwitterionic surfactants include alkyl betaines, such as cocodimethylcarboxymethyl betaine, lauryldimethylcarboxymethyl betaine, lauryldimethylα-carboxyethyl betaine, hexadecyldimethylcarboxymethyl betaine, lauryl bis-(2-hydroxyethyl)carboxymethyl betaine, stearyl bis-(2-hydroxypropyl)carboxymethyl betaine, oleoyldimethylγ-carboxypropyl betaine, lauryl bis-(2-hydroxypropyl)α-carboxyethyl betaine, and amamidopropyl betaine; and alkyl sulfonyl betaines, such as cocodimethylsulfonyl betaine, stearyl dimethylsulfonyl betaine, lauryl dimethylsulfonyl ethyl betaine, lauryl bis-(2-hydroxyethyl)sulfonyl betaine, and alkylamidopropyl hydroxysulfonyl betaine.

[0156] The surfactant used to prepare the materials of the present invention can be amphoteric. Examples of suitable amphoteric surfactants include ammonium salts or substituted ammonium salts of alkyl amphoteric carboxylic acid glycine esters and alkyl amphoteric carboxylic acid propionates, alkyl amphoteric dipropionates, alkyl amphoteric diacetates, alkyl amphoteric glycine esters and alkyl amphoteric propionates, and alkyl imino propionates, alkyl imino dipropionates and alkyl amphoteric propyl sulfonates. Specific examples are cocoamphoacetate, cocoamphoacetate, cocoamphoacetate, lauroyl amphoteric diacetate, lauroyl amphoteric dipropionate, lauroyl amphoteric diacetate, cocoamphoacetate propyl sulfonate, hexamethylene amphoteric diacetate, hexamethylene amphoteric dipropionate and cocoamphoacetate.

[0157] The surfactant used to prepare the materials of the present invention can also be a polymer, such as N-substituted polyisobutylene succinimide and succinate, alkyl methacrylate vinylpyrrolidone copolymer, alkyl methacrylate-dimethylaminoethyl methacrylate copolymer, alkyl methacrylate polyethylene glycol methacrylate copolymer, polystearamide and polyethyleneimine.

[0158] The surfactant used to prepare the material 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).

[0159] The surfactant used to prepare the materials of this invention can be an oil-based dispersant, including alkyl succinimides, succinates, high molecular weight amines, and Mannich bases and phosphoric acid derivatives. Some specific examples are polyisobutylene succinimid-polyethylene polyamine, polyisobutylene succinate, polyisobutylene hydroxybenzyl-polyethylene polyamine, and dihydroxypropyl phosphate.

[0160] The surfactant used to prepare the materials of this invention can be a combination of two or more surfactants of the same or different types selected from anionic, cationic, nonionic, zwitterionic, amphoteric, and ampholytic 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 zwitterionic surfactants, mixtures of three zwitterionic surfactants, mixtures of four zwitterionic surfactants, mixtures of two amphoteric surfactants, mixtures of three zwitterionic surfactants, mixtures of four zwitterionic surfactants, mixtures of two amphoteric surfactants, mixtures of three zwitterionic surfactants, mixtures of four amphoteric surfactants, mixtures of two amphoteric surfactants, mixtures of three zwitterionic surfactants, and mixtures of four zwitterionic surfactants.

[0161] Thin polymer layer material

[0162] The aforementioned techniques 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 advantageously suitable polymers have been described, it should be understood that other polymeric materials can be used, including the following.

[0163] The polymer used to prepare the materials of this invention can be a polymeric material, such as a water-processable polymeric material. In various embodiments, any one (and combinations thereof) of the following polymers can be used: polyacrylic acid (PAA), polyvinyl alcohol (PVA), polyvinyl 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 latex (TRD202A) and is supplied by JSR Corporation.

[0164] Example

[0165] The following non-limiting examples further illustrate the application of the teachings of this disclosure. In the examples below, the term "binder-free" or "adhesive-free" electrode refers to the type of electrode described in detail above, characterized by a 3D matrix or scaffold of high aspect ratio carbon, on which surface treatments promote adhesion of the active material to the scaffold without requiring a large volume of polymeric adhesive, such as PVDF.

[0166] As used below, the term C-rate refers to a measure of the rate at which a battery discharges relative to its maximum capacity. A 1C rate means that the discharge current will discharge the entire battery in one hour. For a 100 Amp-hrs battery, this is equivalent to a discharge current of 100 Amps.

[0167] Example 1 - Electric Vehicle Battery

[0168] The following battery is suitable for electric vehicles (“EVs”). This battery combines the type of cathode and anode technologies described herein for applications such as EVs. Key benefits include lower manufacturing costs, higher energy density, excellent power density, and a wider operating temperature range. These benefits stem from the method described herein for manufacturing the battery electrodes, which eliminates the use of PVDF polymer binders and toxic solvents such as N-methyl-2-pyrrolidone (NMP). As a result, end users experience significant performance advantages in driving range, charging speed, and acceleration, with a lower-cost, less capital-intensive manufacturing process that is also safer for battery manufacturers.

[0169] The teachings in this paper provide a technological platform for fabricating electrodes for energy storage that can exhibit the following advantages: reduced manufacturing costs and lower LIB 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 in this paper also provide a scalable technique for improving power density in energy storage by removing conventional polymer binders from the active material coating.

[0170] Conventional electrodes for LiB are manufactured by mixing active materials, conductive additives, and polymer binders into a slurry. Conventional cathodes are made using NMP-based slurries and PVDF polymer binders. These binders have very high molecular weights and promote the adhesion of active material particles and their bonding with 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, polymer binder-based methods have significant performance drawbacks: power density, energy density, and manufacturing cost.

[0171] The teachings in this paper provide electrodes without PVDF binders in the cathode or other conventional binders in the anode. Alternatively, as described above, a 3D carbon scaffold or matrix holds the active material particles together to form a binder layer that is also firmly attached to the metal current collector. Such active material structures are generated during slurry preparation and subsequently during roll-to-roll (“R2R”) coating and drying processes. One of the main advantages of this technology is its scalability and “insertion” capability, as it is compatible with conventional electrode manufacturing processes.

[0172] Forming a 3D carbon matrix during slurry preparation using the techniques described herein: employing, for example, a two-step slurry preparation process (as referenced above). Figure 6 The high aspect ratio carbon material (of the type described) is appropriately dispersed and chemically functionalized. Chemical functionalization is designed to form an organized self-assembled structure with the surface of the active material particles, such as NMC particles used in cathodes or silicon (“Si”) or silicon oxide (“SiOx”) particles in the anode case. The slurry thus formed can be based on an alcohol solvent for the cathode and water for the anode, and such solvents are very easy to evaporate and handle during manufacturing. Electrostatic interactions promote the self-organized structure in the slurry, and after the drying process, the bonding between the carbon matrix with the active material particles thus formed and the surface of the current collector is promoted by surface treatments (e.g., functional groups on the matrix) and the strong entanglement of the active material in the carbon matrix.

[0173] As those skilled in the art will understand, the mechanical properties of the electrodes can be readily altered by tuning surface functionalization and the winding effect, depending on the application and mass load requirements.

[0174] After coating and drying, the electrode undergoes a calendering step to control the density and porosity of the active material. In the NMC cathode electrode, a density of 3.5 g / cc or higher and a porosity of 20% or higher can be achieved. The porosity can be optimized according to the mass loading and LIB cell requirements. As for the SiOx / Si anode, the porosity is specifically controlled to accommodate the expansion of the active material during the lithiation process.

[0175] In some typical applications, the teachings in this paper can provide reductions of up to 20% in terms of $ / kWh. Higher electrode flux is achieved through the use of readily evaporable, environmentally friendly solvents, and, more importantly, energy consumption from long dryers is significantly reduced. Conventional NMP recovery systems are also greatly simplified when using alcohols or other solvent mixtures.

[0176] The teachings in this paper provide a 3D matrix that significantly improves electrode conductivity by 10 to 100 times compared to electrodes using conventional binders such as PVDF, enabling rapid charging at battery levels. Using this technology, thick electrode coatings of up to 150 μm in the cathode on each side (or more) of the current collector are possible. The solvent used in the slurry, combined with a robust 3D carbon matrix, is designed to achieve thick wet coatings without cracking during the drying step. Thick cathodes combined with high-capacity anodes result in significant improvements in energy density, achieving 400 Wh / kg or higher.

[0177] Fast charging is achieved by combining a high-capacity anode lithiated through an alloying process (Si / SiOx) and by reducing the overall impedance of the battery when combining an anode and cathode as described herein. The teachings herein provide fast charging by having highly conductive electrodes, and in particular, highly conductive cathode electrodes.

[0178] An exemplary embodiment includes a Li-ion battery energy storage device in the form of a pouch cell, which combines a NiNMC-rich active material in the cathode and a mixture of SiOx and graphite active material in the anode, wherein both the anode and cathode are fabricated using the 3D carbon matrix process described herein.

[0179] Figure 7A schematic diagram of the electrode arrangement of a pouch cell device is shown. As shown, a double-sided cathode with a polymer-free binder cathode layer is disposed between two single-sided anodes on opposite sides of an aluminum foil current collector. Each single-sided anode has a polymer-free binder anode layer disposed on a copper foil current collector. The electrodes are separated by a permeable separator material (not shown) wetted by an electrolyte (not shown). This arrangement can be accommodated in pouch cells of types known in the art.

[0180] These devices may be characterized by high-mass-loaded Ni-rich NMC cathode electrodes and their manufacturing methods: mass load = 20-30 mg / cm³ 2 Specific capacity ≥210 mAh / g. Synthesis and manufacturing method of SiOx / graphite anode (SiOx content approximately 20 wt.%) base electrode and its materials: mass loading 8-14 mg / cm³. 2 Reversible specific capacity ≥ 550 mAh / g. Specifically, the long life performance of the SiQx / graphite anode-based Li-ion electrolyte: from -30 to 60℃, high energy, high power density and long cycle life of the Ni-rich NMC cathode / SiOx+graphite / carbon+lithium-ion-based soft-pack battery: capacity ≥ 5 Ah, specific energy ≥ 300Wh / kg, energy density ≥ 800 Wh / L, cycle life of more than 500 cycles at 1C rate charge and discharge, and ultra-high power fast charge and discharge C rate capability (maximum 5C rate). Figure 8 The paper summarizes the performance parameters of this type of pouch battery.

[0181] Example 2 - Comparative Performance of NMC811 Lithium-ion Batteries

[0182] As detailed above, the teachings in this paper provide electrodes configured with advanced 3D high aspect ratio carbon-bonded structures that eliminate the need for polymer binders, offering higher power, energy density (e.g., through thicker electrodes and higher active material mass loading), and performance in extreme environments compared to conventional battery electrode designs. High-performance Li-ion battery energy storage devices are designed and manufactured with binder-free cathode / anode electrodes, pre-lithiated anode electrodes, and electrolytes with wide operating temperature ranges (e.g., -30 to 60 °C) optimized capacity ratio designs, as well as optimized test formation processes.

[0183] As described herein, electrodes are fabricated 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 embodiments, a 3D nanoscale carbon matrix acts as a mechanical scaffold for the electrode active material and mimics polymer chain entanglement. Chemical bonds are also present on the carbon surface, between the active material, and the current collector, promoting adhesion and bonding. 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 better suited for producing thicker electrode active materials, a powerful pathway to increasing the energy density of LiB batteries.

[0184] In this example, a binderless cathode was produced according to the teachings of this disclosure, characterized by NMC811 as the active material and incorporated into a Li-ion battery (LIB). This battery is characterized by a graphite anode of a conventional type known in the prior art. Figure 9 The parameters summarized above are for reference. Figure 7 The battery was constructed using a conventional electrolyte consisting of 1M LiPF6 in a solvent mixture of ethylene carbonate, dimethyl carbonate, and 1% ethylene carbonate additive by weight. In contrast, another identical battery was produced using a PVDF-based binder-coated cathode. The performance of the compared batteries, as described below, demonstrates the significant advantages of the binder-free cathode battery.

[0185] like Figure 10 The results summarized show that, based on a 20 Ah battery design and a graphite anode with a cycle life exceeding 2,000 cycles at a 2C charge / discharge rate, binderless batteries can achieve a specific energy of up to 320 Wh / kg. In contrast, conventional binder-based cathode batteries only achieve a specific energy of 100-250 Wh / kg at the battery level.

[0186] The binderless cathode cell exhibits ultra-high power fast charge / discharge C-rates, up to 5C-rates with >50% capacity retention. Figure 10 A comparison of charge-discharge curves for a binderless cathode cell (left) and a conventional binder-based cathode cell (right) at different C rates is shown. The binderless cathode cell charge-discharge curve shows a capacity retention of over 60% at a combined charge-discharge rate of 5C. Therefore, individual discharge or charge will exhibit even higher capacity retention. Note that in this example, initial experimental results show that a 10C charge rate can be achieved when a Si-based anode is combined with the NMC811 cathode used in this example, with the use of a conventional graphite anode.

[0187] Figure 11A comparison of the cycle life of the above batteries is shown. At 25°C, the batteries were repeatedly cycled between voltages of 2.75 V and 4.2 V, and the discharge capacity was recorded. The binder-free cathode battery exhibited a lifespan of over 2,000 cycles with less than 20% discharge capacity loss. In contrast, the binder-based cathode battery experienced more than 20% discharge capacity loss after only about 1,000 cycles.

[0188] Example 3 - Comparison of Soft-pack Half-cells

[0189] The binderless cathode electrode of the type described herein can advantageously achieve high-quality loading, for example, 45 mg / cm² of NMC811 active material per side. 2 Mass loading is possible. This example illustrates the following experimental results, which demonstrate the performance of a high-mass-loaded binder-free electrode compared to a control electrode characterized by PVDF binder and NMC811 active material.

[0190] 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 for the battery. The half-cell underwent charging rate testing at various current densities, and the results are summarized below.

[0191] Figure 13 This is a graph showing the potential (reference Li / Li+ potential) versus specific capacity of a binderless cathode half-cell (solid trace) and a reference binder-based cathode half-cell (dashed trace) at different current densities. At all current densities (and therefore at all C rates), the binderless cathode half-cell exhibits better performance (as indicated by the relative rightward shift of the trace).

[0192] Figure 14 This is a graph showing the potential (reference Li / Li+ potential) versus volumetric capacity of a binderless cathode half-cell (solid trace) and a reference binder-based cathode half-cell (dashed trace) at different current densities. At all current densities (and therefore at all C rates), the binderless cathode half-cell exhibits better performance (as indicated by the relative rightward shift of the trace).

[0193] Figure 15 The volumetric capacity versus current density is shown for a binderless cathode half-cell (upper trace) and a reference binder-based cathode half-cell (lower trace). The binderless cathode half-cell exhibits better performance at all current densities (and therefore at all C-rates), while the relative performance gap widens at higher C-rates.

[0194] Figure 16Nyquist plots generated from the electrochemical impedance spectroscopy of several binderless cathode half-cells (traces marked with squares, circles, and triangles) and a reference binder-based cathode half-cell are shown. The binderless cathode half-cells exhibit significantly better performance than the reference cell.

[0195] As can be seen from the figure, when the current density increases from 0.5 to 10 mA / cm², 2 At a rate of 1.2C, the binder-free NMC811 electrode exhibited a significantly higher discharge capacity retention compared to the binder-based PVDF control NMC811 electrode, even though both electrodes had the same discharge capacity retention of 45 mg / cm³. 2 Mass load. Note that this C-rate test at different current densities is presented as a relative comparison between conventional binder-based PVDF cathodes and binder-free cathodes, and does not reflect the absolute C-rate performance in full-cell configurations, such as those shown in Examples 1 and 2 above.

[0196] in conclusion

[0197] Any orientation terminology provided herein is for illustrative purposes only and does 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 terms and arrangements may be used without limiting the teachings herein.

[0198] Various other components may be included and invoked to provide aspects of the teachings herein. For example, additional material, combinations of materials, and / or omissions of materials may be used to provide additional embodiments within the scope of the teachings herein.

[0199] Various modifications to the teachings in this document are possible. Typically, 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 that party. Similarly, the acceptability of the performance will be evaluated by the appropriate users, designers, manufacturers, or other similar stakeholders.

[0200] While some chemicals may be listed in this article as providing a certain function, a given chemical may be used for other purposes.

[0201] When describing elements of the invention or embodiments thereof, the articles “a,” “an,” and “the” are intended to indicate the presence of one or more elements. Similarly, the adjective “another,” when used to describe an element, is intended to indicate one or more elements. The terms “comprising” and “having” are intended to be inclusive, such that additional elements may be present in addition to those listed. As used herein, the term “exemplary” is not intended to mean a superlative example. Rather, “exemplary” refers to an embodiment that is one of a plurality of possible embodiments. The entire contents of each of the above-mentioned publications and patent applications are incorporated herein by reference. In the event of any conflict between any of the referenced documents and this disclosure, this disclosure shall prevail.

[0202] Note that unless explicitly stated in the corresponding claims using the terms “means for…” or “steps for…”, any functional language used in the appended claims is not intended to be interpreted as “means plus function” language, as referenced in 35 USC §112(f).

[0203] While the invention has been described with reference to exemplary embodiments, it should be understood that various changes may be made without departing from the scope of the invention, and its elements may be substituted with equivalents. For example, in some embodiments, one of the foregoing layers may include multiple layers therein. Furthermore, many modifications will be understood to adapt particular instruments, 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 for carrying out the invention, but rather the invention will include all embodiments falling within the scope of the appended claims.

[0204] This invention provides the following inventive concept:

[0205] 1. An apparatus comprising:

[0206] Electrode active layer, the electrode active layer comprising:

[0207] A high aspect ratio carbon network, wherein the high aspect ratio carbon network defines void spaces within the network;

[0208] Multiple electrode active material particles, wherein the multiple electrode active material particles are disposed in the void spaces within the network and are entangled in the network; and

[0209] A surface treatment material located on the surface of the high aspect ratio carbon element, the surface treatment material promoting adhesion between the high aspect ratio carbon element and the active material particles.

[0210] 2. The apparatus according to any of the foregoing inventive concepts, wherein the high aspect ratio carbon element comprises elements each having two primary dimensions and one secondary dimension, wherein the length ratio of each of the primary dimensions is at least 10 times the length ratio of the secondary dimension.

[0211] 3. The apparatus according to any of the foregoing inventive concepts, wherein the high aspect ratio carbon element comprises elements each having two primary dimensions and one secondary dimension, wherein the length ratio of each of the primary dimensions is at least 100 times the length ratio of the secondary dimension.

[0212] 4. The apparatus according to any of the foregoing inventive concepts, wherein the high aspect ratio carbon element comprises elements each having two primary dimensions and one secondary dimension, wherein the length ratio of each of the primary dimensions is at least 1,000 times the length ratio of the secondary dimension.

[0213] 5. The apparatus according to any of the foregoing inventive concepts, wherein the high aspect ratio carbon element comprises elements each having two primary dimensions and one secondary dimension, wherein the length ratio of each of the primary dimensions is at least 10,000 times the length ratio of the secondary dimension.

[0214] 6. The apparatus according to any of the foregoing inventive concepts, 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.

[0215] 7. The apparatus according to any of the foregoing inventive concepts, 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 100 times the length ratio of each of the secondary dimensions.

[0216] 8. The apparatus according to any of the foregoing inventive concepts, wherein the high aspect ratio carbon element comprises elements each having a primary dimension and two secondary dimensions, wherein the length ratio of each of the primary dimensions is at least 1,000 times the length ratio of each of the secondary dimensions.

[0217] 9. The apparatus according to any of the foregoing inventive concepts, wherein the high aspect ratio carbon element comprises elements each having a primary dimension and two secondary dimensions, wherein the length ratio of each of the primary dimensions is at least 10,000 times the length ratio of each of the secondary dimensions.

[0218] 10. The apparatus according to any of the foregoing inventive concepts, wherein the high aspect ratio carbon element comprises carbon nanotubes or carbon nanotube bundles.

[0219] 11. The apparatus according to any of the foregoing inventive concepts, wherein the high aspect ratio carbon element comprises graphene sheets.

[0220] 12. The device according to any of the foregoing inventive concepts, wherein the electrode active layer comprises less than 10% by weight of a polymeric adhesive disposed in the void space.

[0221] 13. The device according to any of the foregoing inventive concepts, wherein the electrode active layer comprises less than 1% by weight of a polymer binder disposed in the void space.

[0222] 14. The device according to any of the foregoing inventive concepts, wherein the electrode active layer comprises less than 1% by weight of a polymer binder disposed in the void space.

[0223] 15. The apparatus according to any of the foregoing inventive concepts, wherein the electrode active layer is substantially free of polymeric material, except for the surface treatment.

[0224] 16. The device according to any of the foregoing inventive concepts, wherein the electrode active layer is substantially free of polymeric material.

[0225] 17. The apparatus according to any of the foregoing inventive concepts, wherein the surface-treated material comprises a material soluble in a solvent with a boiling point below 202°C.

[0226] 18. The apparatus according to any of the foregoing inventive concepts, wherein the surface-treated material comprises a material soluble in a solvent with a boiling point below 185°C.

[0227] 19. An apparatus according to any of the foregoing inventive concepts, 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.

[0228] 20. The apparatus according to any of the foregoing inventive concepts, 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.

[0229] 21. The apparatus according to any of the foregoing inventive concepts, wherein during the formation of the active layer, the material forming the surface treatment is dissolved in a solvent containing isopropanol.

[0230] 22. The apparatus according to any of the foregoing inventive concepts, wherein during the formation of the active layer, the material forming the surface treatment is dissolved in a solvent that is substantially free of n-methyl-2-pyrrolidone.

[0231] 23. The apparatus according to any of the foregoing inventive concepts, 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.

[0232] 24. The device according to any of the foregoing inventive concepts, wherein the network is at least 90% carbon by weight.

[0233] 25. The device according to any of the foregoing inventive concepts, wherein the network is at least 95% carbon by weight.

[0234] 26. The device according to any of the foregoing inventive concepts, wherein the network is at least 99% carbon by weight.

[0235] 27. The device according to any of the foregoing inventive concepts, wherein the network is at least 99.9% carbon by weight.

[0236] 28. The apparatus according to any of the foregoing inventive concepts, wherein the network comprises an electrical interconnection network of carbon elements exhibiting connectivity exceeding a percolation threshold.

[0237] 29. The apparatus according to any of the foregoing inventive concepts, wherein the network defines one or more highly conductive paths.

[0238] 30. The apparatus according to inventive concept 29, wherein the path has a length greater than 100 μm.

[0239] 31. The apparatus according to inventive concept 29, wherein the path has a length greater than 1,000 μm.

[0240] 32. The apparatus according to inventive concept 29, wherein the path has a length greater than 10,000 μm.

[0241] 33. The apparatus according to any of the foregoing inventive concepts, wherein the network comprises one or more structures formed of carbon elements, the structures comprising a total length of at least ten times the length of the maximum dimension of the carbon elements.

[0242] 34. The apparatus according to any of the foregoing inventive concepts, wherein the network comprises one or more structures formed of carbon elements, the structures comprising a total length of at least 100 times the length of the maximum dimension of the carbon elements.

[0243] 35. The apparatus according to any of the foregoing inventive concepts, wherein the network comprises one or more structures formed of carbon elements, the structures comprising a total length of at least 1,000 times the length of the maximum dimension of the carbon elements.

[0244] 36. The apparatus according to any of the foregoing inventive concepts, wherein the surface-treated material comprises a surfactant layer disposed on the carbon element.

[0245] 37. The apparatus according to inventive concept 36, wherein the surfactant layer is bonded to the carbon element.

[0246] 38. The apparatus according to inventive concept 36 or 37, wherein the surfactant layer comprises a plurality of surfactant elements, each having a hydrophobic end and a hydrophilic end, wherein the hydrophobic end is disposed proximal to the surface of one of the carbon elements, and the hydrophilic end is disposed distal to the surface of one of the carbon elements.

[0247] 39. The apparatus according to inventive concept 38, wherein at least a portion of the hydrophilic end of the surfactant element forms a bond with the active material particle.

[0248] 40. The apparatus according to inventive concept 39, wherein the bonds include ionic bonds.

[0249] 41. The apparatus according to inventive concept 39, wherein the bond comprises a covalent bond.

[0250] 42. The apparatus according to inventive concept 39, wherein the bonds comprise at least one of the following: π-π bonds, hydrogen bonds, and electrostatic bonds.

[0251] 43. The apparatus according to inventive concept 38, wherein:

[0252] The hydrophilic end of the surfactant element has a first polar charge; and

[0253] The active material particles carry a second polarity charge that is opposite to the first polarity charge.

[0254] 44. The apparatus according to any one of inventive concepts 36 to 43, wherein the surfactant layer comprises a water-soluble surfactant.

[0255] 45. The apparatus according to any one of inventive concepts 36 to 44, wherein the surfactant layer comprises ions from hexadecyltrimethylammonium hexafluorophosphate.

[0256] 46. ​​The apparatus according to any one of inventive concepts 36 to 45, wherein the surfactant layer comprises an ion from at least one of the following compositions: hexadecyltrimethyltetrafluoroborate ammonium, N-(cocoyl)-N,N,N-trimethylmethylammonium sulfate, cocamidopropyl betaine hexadecyltrimethylacetate ammonium, and hexadecyltrimethylammonium nitrate.

[0257] 47. The apparatus according to any one of inventive concepts 36 to 46, wherein the surfactant layer comprises a surfactant ionic layer formed by dissolving an ionic compound in a solvent.

[0258] 48. The apparatus according to inventive concept 47, wherein the active layer comprises residual counterions of the surfactant ions formed by dissolving the ionic surfactant compound in a solvent.

[0259] 49. The apparatus according to inventive concept 48, wherein the counterion is selected to be compatible with use in an electrochemical cell.

[0260] 50. The apparatus according to inventive concept 49, wherein the counterion is substantially free of halogen groups.

[0261] 51. The apparatus according to any one of inventive concepts 48 to 50, wherein the residual counterions are substantially free of bromine.

[0262] 52. The apparatus according to any one of inventive concept 51, wherein the ionic surfactant compound comprises at least one selected from the list of the following: hexadecyltrimethyltetrafluoroborate ammonium, hexadecyltrimethyltetrafluoroborate ammonium, N-(cocoyl)-N,N,N-trimethylmethylammonium sulfate, cocamidopropyl betaine hexadecyltrimethylacetate ammonium, and hexadecyltrimethyl nitrate ammonium.

[0263] 53. The apparatus according to any of the foregoing inventive concepts, wherein the carbon element is functionalized.

[0264] 54. The apparatus according to inventive concept 53, wherein the carbon element is functionalized using a surfactant material.

[0265] 55. The apparatus according to inventive concept 53 or 54, wherein the carbon element is functionalized with functional groups having functional groups that promote the adhesion of the active material particles to the network.

[0266] 56. The apparatus according to inventive concept 55, wherein the functional group comprises at least one of the following groups: carboxyl group, hydroxyl group, amino group and silyl group.

[0267] 57. The apparatus according to any one of inventive concepts 48 to 56, wherein the functionalized carbon element is formed from a dried aqueous dispersion comprising nano-shaped carbon and a surfactant.

[0268] 58. The apparatus according to inventive concept 57, wherein the functionalized carbon element is formed from a freeze-dried aqueous dispersion comprising nano-shaped carbon and a surfactant.

[0269] 59. The apparatus according to any one of inventive concepts 57 to 58, wherein the aqueous dispersion is substantially free of acid.

[0270] 60. An apparatus according to any of the foregoing inventive concepts, wherein the surface treatment comprises a thin polymer layer disposed on the carbon element, the thin polymer layer promoting adhesion between the active material and the network.

[0271] 61. The apparatus according to inventive concept 60, wherein the thin polymer layer comprises a self-assembling polymer.

[0272] 62. The apparatus according to any one of inventive concepts 60 to 61, wherein the thin polymer layer is bonded to the active material by hydrogen bonding.

[0273] 63. The apparatus according to any one of inventive concepts 60 to 62, wherein the thin polymer layer has a maximum thickness of less than or equal to 1 nm in a direction normal to the outer surface of the network.

[0274] 64. The apparatus according to any one of inventive concepts 60 to 63, wherein the thin polymer layer has a maximum thickness of less than or equal to 10 nm in a direction normal to the outer surface of the network.

[0275] 65. The apparatus according to any one of inventive concepts 60 to 64, wherein the thin polymer layer has a maximum thickness of less than or equal to 50 nm in a direction normal to the outer surface of the network.

[0276] 66. The apparatus according to any one of inventive concepts 60 to 65, wherein less than 1% by volume of the void space defined by the network is filled by the thin polymer layer.

[0277] 67. The apparatus according to any one of inventive concepts 60 to 66, wherein less than 0.1% by volume of the void space defined by the network is filled by the thin polymer layer.

[0278] 68. The apparatus according to any one of inventive concepts 60 to 67, wherein less than 0.1% by volume of the void space defined by the network is filled by the thin polymer layer.

[0279] 69. The apparatus according to any one of inventive concepts 1 to 35, wherein the surface-treated material comprises a carbonaceous material layer formed of a pyrolytic polymer.

[0280] 70. The apparatus according to inventive concept 69, wherein the carbonaceous material layer formed of the pyrolytic polymeric material promotes the adhesion of the active material particles to the network.

[0281] 71. The apparatus according to any of the foregoing inventive concepts, wherein the active material particles comprise metal oxides.

[0282] 72. The apparatus according to any of the foregoing inventive concepts, wherein the active material particles comprise lithium metal oxide.

[0283] 73. The device according to any of the foregoing inventive concepts, wherein the active material is wound in the network.

[0284] 74. The apparatus according to any of the foregoing inventive concepts, wherein the surface treatment promotes the adhesion of the active material layer and the current collector layer.

[0285] 75. The apparatus according to inventive concept 74, wherein the surface treatment material includes functional groups bonded to the current collector layer.

[0286] 76. The device according to inventive concept 75, wherein the functional group is bonded to the current collector layer via non-covalent bonds.

[0287] 77. The device according to inventive concept 75, wherein the functional group is bonded to the current collector layer by at least one selected from the list of: π-π bonds, hydrogen bonds, and ionic bonds.

[0288] 78. The device according to any one of inventive concepts 74 to 77, wherein the current collector comprises a metal foil.

[0289] 79. The device according to any one of inventive concepts 74 to 77, wherein the active material layer has a thickness of at least 200 μm in the direction normal to the current collector.

[0290] 80. The device according to any one of inventive concepts 74 to 77, wherein the active material layer has a thickness of at least 300 μm in the direction normal to the current collector.

[0291] 81. The device according to any one of inventive concepts 74 to 77, wherein the active material layer has a thickness of at least 400 μm in the direction normal to the current collector.

[0292] 82. The device according to any of the foregoing inventive concepts further includes an energy storage battery, said energy storage battery comprising:

[0293] A first electrode, the first electrode comprising the active material layer;

[0294] Second electrode;

[0295] A permeable septum, wherein the permeable septum is disposed between the first electrode and the second electrode; and

[0296] An electrolyte that wets the first and second electrodes.

[0297] 83. A method comprising:

[0298] High aspect ratio carbon elements and surface treatment materials are dispersed in a solvent to form an initial slurry, wherein the dispersion step results in the formation of a surface treatment on the high aspect ratio carbon.

[0299] The active material is mixed into the first slurry to form the final slurry;

[0300] The final slurry is then applied to the substrate; and

[0301] The final slurry is dried to form the electrode active layer.

[0302] 84. The method according to inventive concept 83, wherein the high aspect ratio carbon element comprises elements each having two primary dimensions and one secondary dimension, wherein the length ratio of each of the primary dimensions is at least 10 times the length ratio of the secondary dimension.

[0303] 85. The method according to inventive concept 83 or 84, wherein the high aspect ratio carbon element comprises elements each having two primary dimensions and one secondary dimension, wherein the length ratio of each of the primary dimensions is at least 100 times the length ratio of the secondary dimension.

[0304] 86. The method according to any one of inventive concepts 83 to 85, wherein the high aspect ratio carbon element comprises elements each having two primary dimensions and one secondary dimension, wherein the length ratio of each of the primary dimensions is at least 1,000 times the length ratio of the secondary dimension.

[0305] 87. The method according to any one of inventive concepts 83 to 86, wherein the high aspect ratio carbon element comprises elements each having two primary dimensions and one secondary dimension, wherein the length ratio of each of the primary dimensions is at least 10,000 times the length ratio of the secondary dimension.

[0306] 88. The method according to any one of inventive concepts 83 to 87, 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.

[0307] 89. The method according to any one of inventive concepts 83 to 88, 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 100 times the length ratio of each of the secondary dimensions.

[0308] 90. The method according to any one of inventive concepts 83 to 89, 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 1,000 times the length ratio of each of the secondary dimensions.

[0309] 91. The method according to any one of inventive concepts 83 to 90, wherein the high aspect ratio carbon element comprises elements each having a primary dimension and two secondary dimensions, wherein the length ratio of each of the primary dimensions is at least 10,000 times the length ratio of each of the secondary dimensions.

[0310] 92. The method according to any one of inventive concepts 83 to 91, wherein the high aspect ratio carbon element comprises carbon nanotubes or carbon nanotube bundles.

[0311] 93. The method according to any one of inventive concepts 83 to 92, wherein the high aspect ratio carbon element comprises graphene sheets.

[0312] 94. The method according to any one of inventive concepts 83 to 93, wherein the initial slurry has a solids content in the range of 0.1% to 20.0% by weight.

[0313] 95. The method according to any one of inventive concepts 83 to 94, wherein the final slurry has a solids content in the range of 10.0% to 80% by weight.

[0314] 96. The method according to any one of inventive concepts 83 to 95, wherein the solvent has a boiling point below 202°C.

[0315] 97. The method according to any one of inventive concepts 83 to 96, wherein the solvent has a boiling point below 185°C.

[0316] 98. The method according to any one of inventive concepts 83 to 97, wherein the solvent has a boiling point below 125°C.

[0317] 99. The method according to any one of inventive concepts 83 to 98, wherein the solvent has a boiling point of less than or equal to 100°C.

[0318] 100. The method according to any one of inventive concepts 83 to 99, wherein the solvent comprises at least one from the list of the following: methanol, ethanol, 2-propanol and water.

[0319] 101. The apparatus according to any one of inventive concepts 83 to 100, 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.

[0320] 102. The method according to any one of inventive concepts 83 to 101, wherein the solvent is substantially free of n-methyl-2-pyrrolidone.

[0321] 103. The method according to any one of inventive concepts 83 to 102, wherein the surface treatment material comprises a surfactant.

[0322] 104. The method according to inventive concept 103, wherein the surfactant is substantially free of halogen groups.

[0323] 105. The method according to inventive concept 104, wherein the surfactant is substantially bromine-free.

[0324] 106. The method according to any one of inventive concepts 83 to 105, wherein forming the surface-treated material includes forming a surfactant layer disposed on the carbon element.

[0325] 107. The method according to any one of inventive concepts 83 to 106, wherein the surface-treated material is a self-assembled layer.

[0326] 108. The method according to inventive concept 106 or 107, wherein forming the surfactant layer comprises disposing of a plurality of surfactant elements on the surface of the carbon element, each of the surfactant elements having a hydrophobic end and a hydrophilic end, wherein the hydrophobic end is disposed proximal to the surface of one of the carbon elements, and the hydrophilic end is disposed distal to the surface of one of the carbon elements.

[0327] 109. The method according to inventive concept 108 further includes forming a bond between at least a portion of the hydrophobic end of the surfactant element and the active material particle.

[0328] 110. The method according to inventive concept 109, wherein the bond comprises an ionic bond.

[0329] 111. The method according to inventive concept 109, wherein the bond comprises a covalent bond.

[0330] 112. The method according to inventive concept 109, wherein the bond comprises at least one of the following: π-π bond, hydrogen bond and electrostatic bond.

[0331] 113. The method according to inventive concept 108, wherein:

[0332] The hydrophilic end of the surfactant element has a first polar charge;

[0333] The active material particles carry a second polarity charge that is opposite to the first polarity charge.

[0334] 114. The method according to any one of inventive concepts 103 to 113, wherein the surfactant material comprises at least one selected from the list of the following: hexadecyltrimethyltetrafluoroborate ammonium, hexadecyltrimethyltetrafluoroborate ammonium, N-(cocoyl)-N,N,N-trimethylmethylammonium sulfate, cocamidopropyl betaine hexadecyltrimethylacetate ammonium, and hexadecyltrimethyl nitrate ammonium.

[0335] 115. The method according to any one of inventive concepts 83 to 114, wherein dispersing high aspect ratio carbon elements and surface treatment materials in a solvent to form an initial slurry includes applying a force to the aggregated carbon elements to cause the elements to slide apart from each other in a direction transverse to the short axis of the elements.

[0336] 116. The method according to any one of inventive concepts 83 to 114, comprising drying the final slurry at a temperature below 202°C.

[0337] 117. The method according to any one of inventive concepts 83 to 114, comprising drying the final slurry at a temperature below 185°C.

[0338] 118. The method according to any one of inventive concepts 83 to 114, comprising drying the final slurry at a temperature below 125°C.

[0339] 119. The method according to any one of inventive concepts 83 to 114, comprising drying the final slurry at a temperature below or equal to 100°C.

[0340] 120. The method according to any one of inventive concepts 83 to 119 further includes calendering the active layer to promote adhesion between the active material and the network.

[0341] 121. A method comprising:

[0342] High aspect ratio carbon elements and surface treatment materials are dispersed 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

[0343] The initial slurry is dried to remove substantially all moisture, thereby obtaining a dried powder of the high aspect ratio carbon having the surface treatment thereon.

[0344] 122. The method according to inventive concept 121, wherein drying the initial slurry comprises freeze-drying the initial slurry.

[0345] 123. The method according to inventive concept 121 or inventive concept 122, wherein the aqueous solvent and the initial slurry are substantially free of substances that would impair the high aspect ratio carbon element.

[0346] 124. The method according to inventive concept 123, wherein the aqueous solvent and the initial slurry are substantially free of acid.

[0347] 125. The method according to inventive concept 124, wherein the initial slurry is substantially composed of the high aspect ratio carbon element, the surface treatment material and water.

[0348] 126. The method according to any one of inventive concepts 121 to 125, further comprising:

[0349] The dry powder of the high aspect ratio carbon having the surface treatment is dispersed in a solvent, and an active material is added to form a second slurry;

[0350] The second slurry is coated onto the substrate; and

[0351] The second slurry is dried to form the electrode active layer.

[0352] 127. The method according to any one of inventive concepts 121 to 126, wherein the high aspect ratio carbon element comprises elements each having two primary dimensions and one secondary dimension, wherein the length ratio of each of the primary dimensions is at least 10 times the length ratio of the secondary dimension.

[0353] 128. The method according to any one of inventive concepts 121 to 127, wherein the high aspect ratio carbon element comprises elements each having two primary dimensions and one secondary dimension, wherein the length ratio of each of the primary dimensions is at least 100 times the length ratio of the secondary dimension.

[0354] 129. The method according to any one of inventive concepts 121 to 128, wherein the high aspect ratio carbon element comprises elements each having two primary dimensions and one secondary dimension, wherein the length ratio of each of the primary dimensions is at least 1,000 times the length ratio of the secondary dimension.

[0355] 130. The method according to any one of inventive concepts 121 to 129, wherein the high aspect ratio carbon element comprises elements each having two primary dimensions and one secondary dimension, wherein the length ratio of each of the primary dimensions is at least 10,000 times the length ratio of the secondary dimension.

[0356] 131. The method according to any one of inventive concepts 121 to 130, wherein the high aspect ratio carbon element comprises elements each having a 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.

[0357] 132. The method according to any one of inventive concepts 121 to 131, 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 100 times the length ratio of each of the secondary dimensions.

[0358] 133. The method according to any one of inventive concepts 121 to 132, wherein the high aspect ratio carbon element comprises elements each having a primary dimension and two secondary dimensions, wherein the length ratio of each of the primary dimensions is at least 1,000 times the length ratio of each of the secondary dimensions.

[0359] 134. The method according to any one of inventive concepts 121 to 133, wherein the high aspect ratio carbon element comprises carbon nanotubes or carbon nanotube bundles.

[0360] 135. The method according to any one of inventive concepts 121 to 134, wherein the high aspect ratio carbon element comprises graphene sheets.

[0361] 136. The method according to any one of inventive concepts 121 to 135, wherein the solvent has a boiling point below 202°C.

[0362] 137. The method according to any one of inventive concepts 121 to 135, wherein the solvent has a boiling point below 185°C.

[0363] 138. The method according to any one of inventive concepts 121 to 135, wherein the solvent has a boiling point below 125°C.

[0364] 139. The method according to any one of inventive concepts 121 to 135, wherein the solvent has a boiling point of less than or equal to 100°C.

[0365] 140. The method according to inventive concepts 121 to 139, wherein the second solvent comprises at least one from the list of the following: methanol, ethanol, 2-propanol and water.

[0366] 141. The method according to any one of inventive concepts 121 to 140, wherein the second solvent is substantially free of pyrrolidone compounds.

[0367] 142. The method according to any one of inventive concepts 121 to 141, wherein the second solvent is substantially free of n-methyl-2-pyrrolidone.

[0368] 143. The method according to any one of inventive concepts 121 to 142, wherein the surface treatment material comprises a surfactant.

[0369] 144. The method according to inventive concept 143, wherein the surfactant is substantially free of halogen groups.

[0370] 145. The method according to inventive concept 144, wherein the surfactant is substantially bromine-free.

[0371] 146. The method according to any one of inventive concepts 121 to 145, wherein forming the surface-treated material includes forming a surfactant layer disposed on the carbon element.

[0372] 147. The method according to inventive concept 146, wherein the surfactant layer is a self-assembled layer.

[0373] 148. The method according to any one of inventive concepts 126 to 147, comprising drying the second slurry at a temperature below 202°C.

[0374] 149. The method according to any one of inventive concepts 126 to 147, comprising drying the second slurry at a temperature below 185°C.

[0375] 150. The method according to any one of inventive concepts 126 to 147, comprising drying the second slurry at a temperature below 125°C.

[0376] 151. The method according to any one of inventive concepts 126 to 147, comprising drying the second slurry at a temperature below or equal to 100°C.

[0377] 152. The method according to any one of inventive concepts 121 to 151 further includes calendering the active layer to promote adhesion.

Claims

1. An electrode, comprising: A current collector, on which an electrode active layer is disposed; The electrode active layer includes: A network of high aspect ratio carbon elements, wherein the network of high aspect ratio carbon elements defines a void space within the network; wherein the network of high aspect ratio carbon elements comprises elongated rod-shaped or fibrous elements having one primary dimension and two secondary dimensions, and wherein the length ratio of the primary dimension is at least 5 times or more the length ratio of each of the secondary dimensions. Multiple electrode active material particles, wherein the multiple electrode active material particles are disposed in the void spaces within the network and are entangled in the network; and A surface treatment material located on the surface of the high aspect ratio carbon element, the surface treatment material promoting adhesion between the high aspect ratio carbon element and the active material particles; wherein the surface treatment material comprises a surfactant; and wherein the surfactant is an ionic surfactant compound comprising at least one selected from the list consisting of: hexadecyltrimethylammonium hexafluorophosphate, hexadecyltrimethylammonium tetrafluoroborate, cocamidopropyl betaine hexadecyltrimethylacetate, and hexadecyltrimethylammonium nitrate.

2. The electrode according to claim 1, wherein the active material particles comprise lithium metal oxide.

3. The electrode according to claim 2, 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, or lithium iron phosphate oxide.

4. The electrode according to claim 3, wherein the lithium cobalt oxide is LiCoO2, the lithium nickel manganese cobalt oxide is LiNiMnCoO2, 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.

5. The electrode according to claim 3, wherein the lithium nickel manganese cobalt oxide is LiNi x Mn y Co 1-x-y O2, where x is equal to or greater than 0.7, and y is 0.

1.

6. The electrode according to claim 3, wherein the lithium nickel manganese cobalt oxide 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.

7. The electrode according to claim 1, wherein the high aspect ratio carbon element comprises at least one of carbon nanotubes and carbon nanotube bundles.

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

9. The electrode of claim 1, wherein the surfactant forms a surfactant layer, the surfactant layer is bound to the carbon element and includes a plurality of surfactant elements each 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.

10. The electrode of claim 1, wherein the surfactant provides functional groups that promote adhesion between the active material particles and the network.

11. The electrode of claim 1, wherein the surfactant includes a hydrophilic end having a first polar charge, and wherein the active material particles carry a second polar charge opposite to the first polar charge.

12. The electrode of claim 1, wherein the surfactant comprises ions formed by dissolving an ionic compound in a solvent.

13. The electrode of claim 1, wherein the electrode active layer comprises residual counterions of surfactant ions obtained from the surfactant; wherein the surfactant is an ionic surfactant, and wherein the surfactant ions are formed by dissolving the ionic surfactant compound in a solvent.

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