Electrode for energy storage equipment

Abstract

The application discloses an electrode for an energy storage device. The electrode includes an active layer. The active layer comprises a network structure formed by carbon elements with high aspect ratio, the carbon elements define void spaces in the network, electrode active material particles are distributed in the void spaces in the network, and the active material particles comprise silicon and a polymer additive. The polymer additive comprises at least one of polyolefin, polyacrylic acid or styrene butadiene rubber (SBR).

Description

Cross-references to related applications

[0001] This application claims priority to U.S. Patent Application No. 18,220,050, filed July 10, 2023, which is a continuation-in-part of U.S. Patent Application No. 18 / 081,057, filed December 14, 2022, which claims the benefit of U.S. Patent Application No. 63 / 290,284, filed December 16, 2021, the entire contents of which are incorporated herein by reference. Background Technology

[0002] Lithium-ion batteries are widely used in various products, including medical devices, electric vehicles, aircraft, and consumer products such as laptops, mobile phones, and cameras. With their high energy density, high operating voltage, and low self-discharge characteristics, lithium-ion batteries have dominated the rechargeable battery market and continue to expand into new application areas across various products and emerging industries.

[0003] Typically, lithium-ion batteries (LIBs or LiBs) consist of a negative electrode, a positive electrode, and an electrolyte material (such as an organic solvent containing lithium salts). More specifically, the negative and positive electrodes (collectively referred to as "electrodes") are made by mixing any of the following materials: a negative or positive electrode active material is mixed with a binder and a solvent to form a paste or slurry, which is then coated onto a current collector such as aluminum or copper and dried to form a thin film on the current collector surface. The negative and positive electrodes are then layered or wound together and placed in a pressurized casing containing the electrolyte material, ultimately forming a lithium-ion battery.

[0004] Traditional electrodes employ adhesives with sufficient adhesion and chemical properties to ensure that the thin film coated on the current collector remains in contact with it even when installed in a pressurized battery casing. Since the film contains the electrode active materials, insufficient contact with the current collector will significantly affect the battery's electrochemical performance. Furthermore, selecting an adhesive that mechanically interacts with the electrode active materials is crucial; it must be able to withstand the expansion and contraction of the active materials during battery charging and discharging. Therefore, materials such as cellulose adhesives or cross-linked polymer adhesives are currently used to provide excellent mechanical properties. However, in traditional electrodes, the adhesives selected often require processing with environmentally unfriendly or toxic solvents.

[0005] Another key area for improving the performance of energy storage devices in such electronic devices lies in the application of silicon-based anodes in lithium-ion batteries. Although silicon exhibits excellent charge storage properties, it undergoes significant mechanical expansion during charging, which can lead to electrode structure failure and render it unsuitable for application requirements.

[0006] Therefore, researchers have been working to utilize silicon-carbon composite structures to fabricate high-performance electrodes that exhibit good mechanical stability during charge and discharge. For example, see international patent application PCT / US2019 / 013261 entitled "Silicon Microreactor for Lithium-ion Rechargeable Batteries," the entire contents of which are hereby incorporated by reference, which discloses a method for fabricating a composite silicon-carbon anode. Another example is US Patent No. 10,340,520, published July 2, 2019, entitled "Nanocomposite Battery Electrode Particles with Variable Permeability," the entire contents of which are hereby incorporated by reference, which discloses silicon-carbon nanoshell particles for use as electrodes.

[0007] However, in many cases, such methods are not suitable for rapid, low-cost manufacturing and may have several other disadvantages. For example, electrodes prepared using these methods sometimes require the addition of polymer binders, which can reduce electrode performance and may make them unsuitable for operating conditions such as high pressure or high temperature.

[0008] The demand for power and energy from energy storage devices such as batteries and capacitors continues to grow. An urgent priority is to drive advancements in the physics and chemistry of electrode technology to achieve these performance improvements.

[0009] The production of lithium-ion batteries typically relies on toxic and expensive components such as solvents and fluoropolymers to ensure the final energy storage device achieves the required stability and performance. Recovering toxic and / or expensive solvents during manufacturing increases costs and process complexity. Furthermore, fluorinated binders (such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE)) belong to the perfluorinated and polyfluoroalkyl substances (PFAS), whose decomposition products are toxic and can accumulate in organisms.

[0010] The field of energy storage device electrode manufacturing still urgently needs more environmentally friendly, economical, and PFAS-free solutions. Attached Figure Description

[0011] The following is a brief description of the accompanying drawings, in which the same elements are numbered the same. These drawings are intended to illustrate the exemplary embodiments disclosed in this application and are not intended to limit the scope thereof.

[0012] Figure 1A This is a schematic diagram of electrodes according to various implementation methods;

[0013] Figure 1B This is a schematic diagram of electrodes according to various implementation methods;

[0014] Figure 1C This is a schematic diagram of electrodes according to various implementation methods;

[0015] Figure 2 This is a schematic diagram of electrodes according to various implementation methods;

[0016] Figure 3 This is a schematic diagram of electrodes according to various implementation methods;

[0017] Figure 4 Examples of electron microscope images of the active layer according to various embodiments;

[0018] Figure 5 This is a schematic diagram of an energy storage device;

[0019] Figure 6 This is a flowchart of electrode fabrication methods according to various implementation methods;

[0020] Figure 7 This is a schematic diagram of a pouch cell battery;

[0021] Figure 8 It is a cross-sectional schematic diagram showing part of the structure of the energy storage device (ESD);

[0022] Figure 9 yes Figure 8 A cross-sectional schematic diagram of an existing energy storage cell for medium-voltage energy storage devices (ESD);

[0023] Figures 10 to 19 This is a schematic diagram of the electrical performance of an energy storage cell assembled according to various implementation methods;

[0024] Figure 20 This is a schematic diagram of an energy storage cell assembled according to various implementation methods;

[0025] Figure 21 This is a schematic diagram of an energy storage battery assembled according to various embodiments;

[0026] Figure 22 These are electrical performance diagrams of energy storage cells assembled according to various implementation methods;

[0027] Figures 23 to 29 This is a schematic diagram of the electrical performance of an energy storage cell assembled according to various implementation methods;

[0028] Figure 30 These are electrical performance charts of energy storage batteries assembled according to various embodiments;

[0029] Figure 31 These are electrical performance diagrams of energy storage cells assembled according to various implementation methods;

[0030] Figures 32 to 33 This is a schematic diagram of the electrical performance of energy storage cells assembled according to various implementation methods;

[0031] Figures 34 to 36 This is a schematic diagram of the electrical performance of an energy storage cell assembled according to various implementation methods;

[0032] Figures 37 to 41 It is a specific capacity diagram for energy storage cells with different positive and negative electrode compositions in their respective cells. Detailed Implementation

[0033] The components, processes, and apparatus described in this application can be more fully understood by referring to the accompanying drawings. These drawings are merely illustrative representations for convenience and to facilitate the explanation of the application, and are therefore not intended to indicate the relative dimensions and specifications of the apparatus or its components, nor are they intended to define or limit the scope of the exemplary embodiments. Although specific terms are used in the following description for clarity, these terms refer only to the specific structures of the embodiments selected in the illustrations and are not intended to define or limit the scope of this application. In the drawings and the following description, it should be understood that the same numbering corresponds to components with the same function.

[0034] Various embodiments provide an energy storage device including a negative electrode with a high silicon particle loading. Silicon is low in cost and has a high specific capacity, thus it can be used to increase the capacity of energy storage devices. However, during the charging phase of the energy storage device, silicon expands. This expansion of silicon during charging can generate mechanical stress on the negative electrode. Embodiments of this application provide a robust carbon network structure that provides strong mechanical support for the negative electrode, ensuring that the energy storage device maintains electrical connectivity and mechanical toughness during charge-discharge cycles.

[0035] Various embodiments provide an electrode with robust electrical properties and mechanical stability, comprising a polymeric additive that facilitates safe and clean manufacturing processes and improves energy storage devices. Various embodiments provide an electrode that does not (e.g., is free from) polymeric additives insoluble in one or more alcohols such as water or ethanol. In some embodiments, the electrode is substantially free of polymeric additives insoluble in one or more alcohols such as water or ethanol. In some embodiments, the active layer of the electrode is free of or substantially free of polymeric additives insoluble in one or more alcohols such as water or ethanol. For example, according to various embodiments, any polymeric additive added to the electrode is soluble in one or more water and alcohol solvents.

[0036] According to various embodiments, the electrode includes an active layer. In some embodiments, the active layer includes: (i) a network of high aspect ratio carbon elements defining void spaces within the network; (ii) a plurality of electrode active material particles disposed within the void spaces of the network, wherein the active material particles comprise silicon; and (iii) a polymer additive. In some embodiments, the silicon contained in the active material particles comprises one or more of silicon oxide and microsilicon. In some embodiments, the polymer additive is water-treatable.

[0037] This application also discloses a semi-dry process for preparing electrode slurry, which includes mixing carbonaceous conductive material, solvent, active material and polymer binder to form electrode slurry, wherein the fluorine content of the electrode slurry is less than 900 ppm.

[0038] This application also discloses a battery cell comprising a positive electrode having a positive current collector and a positive electrode active layer, wherein the positive electrode active layer comprises one or more of the following materials: LFP, LiCoO2, LiNiO2, LiNiMnCoO2, LiNiO2, LiMn2O4, LiFePO4, LiNixMnyCo 1-x-y O2, nickel cobalt manganese (NCM), nickel cobalt manganese aluminum (NCMA), or combinations thereof, wherein the x-value is 0.7 to 0.85 and the y-value is greater than 0.1; the negative electrode comprises a negative electrode current collector and a negative electrode active layer; wherein the negative electrode active layer comprises a negative electrode active material, which is composed of graphite and Li x Si y O z The mixture is composed of x, y, z, and z, where x is 1 to 15, y is 1 to 4, and z is 1 to 9; the negative electrode active layer is in contact with the negative electrode current collector; both the negative electrode active layer and the positive electrode active layer contain carbon elements with a high aspect ratio; the fluorine content of the battery cell is less than 900 ppm.

[0039] In one embodiment, the positive electrode active layer comprises lithium manganese iron phosphate (LMFP). Its chemical formula is LiMn. x Fe 1-x The LMFP of PO4 (where x values ​​are 0.03 to 0.95, preferably 0.1 to 0.7, more preferably 0.25 to 0.5) combines the high safety of LiFePO4 with the high energy density of LiMnPO4. Variants of LMFP, such as LiMnPO4, can also be used. 1-y Fe y PO4, (where the y value ranges from 0.05 to 0.4).

[0040] Adding manganese to the LFP cathode can achieve higher energy density without significantly increasing cost. Therefore, LMFP cells offer higher energy density than LFP cells, but their cost remains far lower than NCM or NCA cells. In one embodiment, the anode layer of the cell contains SiO2. x (as the active material), while the positive electrode layer uses LMFP as the active material.

[0041] This application also discloses an energy storage device, including: a shell; a diaphragm; and a positive electrode and a negative electrode disposed within the shell; wherein the negative electrode and the positive electrode are respectively disposed on opposite sides of the diaphragm; and each of the positive electrode and the negative electrode includes a current collector, on which an active layer is disposed; the active layer includes a carbonaceous conductive material, an active substance and a binder; wherein the fluorine content of the active layer is less than 900 ppm.

[0042] In one exemplary embodiment, this application discloses an energy storage device including a negative electrode and a positive electrode disposed on opposite sides of a diaphragm. The active layer used in the negative electrode (i.e., the negative electrode active layer) comprises the negative electrode active material SiO. x (Where x is 1 to 4, preferably 3 to 4) and a binder with a fluorine content of less than 900 ppm. Based on the total weight of the negative electrode active layer, SiO x The content can be 5-80wt%, preferably 10-70wt%, and more preferably 20-60wt%.

[0043] In one embodiment, the negative electrode active layer may also comprise graphite. Preferably, graphite-SiO2 is used. x Composite anode active material, calculated by the total weight of the anode active layer, wherein SiO x The content of the active material accounts for 5-80% of the total weight of the negative electrode active material, preferably 10-70%, more preferably 20-60%, with the remainder being graphite. The content of the active material in the negative electrode active layer is greater than 85 wt%, preferably greater than 90 wt%, more preferably greater than or equal to 95 wt%, with the remainder being a fluorine-free binder. The fluorine-free binder contains less than 900 ppm of fluorine, as detailed in other parts of this application. The negative electrode layer may also contain conductive additives, the details of which are provided in other parts of this document.

[0044] The active layer used in the positive electrode comprises a mixture of LMFP and NCM, with a mixing ratio between 0-100 wt% based on the total weight of LMFP and NCM. In a preferred embodiment, the LMFP is LiMn. x Fe 1-x PO4 (where x is 0.03-0.4, preferably 0.1-0.3). NCM is NCM811 (containing 80wt% nickel, 10wt% cobalt and 10wt% manganese in a ratio of 8:1:1). Other forms of NCM, such as NCM111, NCM523, and NCM622, can also be used. Any of the above NCM combinations can be used in conjunction with LMFP.

[0045] In one embodiment, the content of LMFP in the positive electrode active material, calculated by total weight, is 0.05-100 wt%, preferably 1-30 wt%, more preferably 10-25 wt%, with the remainder being NMC. In one embodiment, the positive electrode active layer comprises the positive electrode active material and a fluorine-free binder. The fluorine-free binder contains less than 900 ppm of fluorine, as detailed in other parts of this application. The positive electrode layer may also contain conductive additives, the details of which are provided in other parts of this application.

[0046] In some embodiments, the polymer additive comprises one or more of polyolefins, polyacrylic acid, and styrene-butadiene rubber (SBR). In some embodiments, the amount of polymer material contained in the active layer is approximately 8% of the weight of the active layer. In some embodiments, the amount of polymer material contained in the active layer is equal to or less than 8% of the weight of the active layer. In some embodiments, the amount of polymer material contained in the active layer is approximately 10% of the weight of the active layer. In some embodiments, the amount of polymer material contained in the active layer is equal to or less than 10% of the weight of the active layer. In some embodiments, the amount of polymer material contained in the active layer is less than 12% of the weight of the active layer. In some embodiments, the amount of polymer material contained in the active layer is less than 15% of the weight of the active layer.

[0047] According to various embodiments, the active layer comprises a polymer additive comprising a polyolefin. In some embodiments, the polyolefin has an average particle size of 1 µm or less. In some embodiments, the polyolefin comprises an unsaturated hydrocarbon having 3 to 6 carbon atoms, and at least one of a propylene component or a 1-butene component. In some embodiments, the polymer additive comprising the polyolefin is prepared from a polyolefin resin comprising 50-95% by mass of an unsaturated hydrocarbon having 3 to 6 carbon atoms, and 0.5-20% by mass of an unsaturated carboxylic acid unit. In some embodiments, the polyolefin comprises an ethylene component. In some embodiments, the polyolefin comprises: (i) an unsaturated hydrocarbon having 3 to 6 carbon atoms, and at least one of a propylene component and a 1-butene component, and (ii) an ethylene component. In some embodiments, the polyolefin comprises a crosslinking agent and / or a tackifier. In some embodiments, the polyolefin comprises at least one selected from maleic anhydride, acrylic acid, and methacrylic acid.

[0048] According to various embodiments, the electrode includes an active layer. In some embodiments, the active layer includes: (i) a network of high aspect ratio carbon elements defining void spaces within the network; (ii) a plurality of electrode active material particles disposed within the void spaces of the network; and (iii) a polymer additive. In some embodiments, the polymer additive includes one or more of polyolefins, polyacrylic acid, and styrene-butadiene rubber (SBR). In some embodiments, the silicon contained in the active material particles includes one or more of silicon oxide and microsilicon.

[0049] In some embodiments, the active layer comprises silicon-based particles accounting for 20%-95% of its weight. In some embodiments, the active layer comprises silicon-based particles accounting for 50%-95% of its weight. In some embodiments, the active layer comprises silicon-based particles accounting for more than 75% of its weight. In some embodiments, the active layer comprises silicon-based particles accounting for more than 80% of its weight. In some embodiments, the active layer comprises silicon-based particles accounting for 20%-75% of its weight. In some embodiments, the active layer comprises silicon particles (e.g., microsilicon) accounting for more than 20% of its weight. In some embodiments, the active layer comprises silicon particles (e.g., microsilicon) accounting for 20%-40% of its weight. In some embodiments, the active layer comprises silicon particles (e.g., microsilicon) accounting for 30%-40% of its weight. In some embodiments, the active layer comprises silicon oxide particles accounting for more than 50% of its weight. In some embodiments, the active layer comprises silicon oxide particles accounting for 60%-70% of its weight.

[0050] In other embodiments, the negative electrode active material may comprise microparticles or nanoparticles of elemental silicon, which may be in their raw state or processed, and may be used alone or in combination with other negative electrode active materials. In one embodiment, the negative electrode layer comprises SiO₂. x The negative electrode active material exists in the form of an x-value between 2.5 and 5, preferably 3 to 4. Based on the total weight of the negative electrode active layer, SiO... x The negative electrode mass fraction is between 0.05 and 0.4%. In other words, the SiO₂ content in the negative electrode active layer... x The content of it can account for 5-40 wt% of the total weight of the active layer, preferably 10-30 wt%.

[0051] According to various embodiments, the active layer comprises silicon-based particles. In some embodiments, the active layer comprises both microsilicon particles and silicon oxide particles. In some embodiments, the active layer comprises microsilicon particles and is substantially free of silicon oxide particles (e.g., the active layer does not contain any silicon oxide particles). The expansion of silicon oxide particles appears to be less than that of microsilicon (such as pure silicon). For example, the oxide layer surrounding silicon is large enough that the expansion of silicon in the silicon oxide typically does not result in a significant increase in the volume of the silicon oxide. In contrast, microsilicon expands and contracts more than silicon oxide, which makes maintaining the electrical and / or mechanical properties of the electrode (e.g., the negative electrode) more challenging. For example, the expansion of microsilicon may disrupt electrical connections within the electrode (such as within the active layer) or affect the mechanical stability of the electrode. Various embodiments maintain electrical connections and mechanical support during charge-discharge cycles by constructing a high aspect ratio carbon network. In one embodiment, the negative electrode layer comprises SiO₂. x The negative electrode active material exists in the form of an x-value between 2.5 and 5, preferably 3 to 4. Based on the total weight of the negative electrode active layer, SiO...x The negative electrode mass fraction is between 0.05 and 0.4.

[0052] According to various embodiments, the electrode includes an active layer. In some embodiments, the active layer includes: (i) a network of high aspect ratio carbon elements defining void spaces within the network; (ii) a plurality of electrode active material particles disposed within the void spaces of the network, the plurality of electrode active material particles comprising a plurality of silicon-based particles (e.g., microsilicon, silicon oxide, etc.); and (iii) a polymer additive. The polymer additive has a high molecular weight. In some embodiments, the molecular weight of the polymer additive is at least 400,000 g / mol. In some embodiments, the molecular weight of the polymer additive is at least 1,000,000 g / mol. In some embodiments, the molecular weight of the polymer additive is at least 1,500,000 g / mol. In some embodiments, the molecular weight of the polymer additive is between 700,000 g / mol and 1,500,000 g / mol. In some embodiments, the molecular weight of the polymer additive is between 500,000 g / mol and 1,000,000 g / mol.

[0053] According to various embodiments, the electrode includes an active layer. In some embodiments, the active layer includes: (i) a network of high aspect ratio carbon elements defining void spaces within the network; (ii) a plurality of electrode active material particles disposed within the void spaces of the network, the plurality of electrode active material particles comprising a plurality of silicon-based particles (e.g., microsilicon, silicon oxide, etc.); and (iii) a polymer additive. The polymer additive has high tensile strength. For example, the polymer additive comprises a polymer that is not easily stretched. In some embodiments, the polymer additive has high tensile strength and can be processed in water or alcohol. In some embodiments, the polymer additive has high tensile strength and can be processed in water (e.g., it is relatively easy to process using water). In some embodiments, the polymer exhibits a stress greater than 20 MPa at a strain of approximately 10%. In some embodiments, the polymer exhibits a stress greater than 30 MPa at a strain of approximately 10%. In some embodiments, the polymer exhibits a stress of 30-35 MPa at a strain of approximately 10%. In some embodiments, the polymer exhibits a stress greater than 10 MPa at a strain of approximately 20%. In some embodiments, the polymer exhibits a stress greater than 20 MPa at a strain of approximately 20%. In some embodiments, the polymer exhibits a stress greater than 25 MPa at a strain of approximately 20%. In some embodiments, the polymer exhibits a stress of 25-30 MPa at a strain of approximately 20%. In some embodiments, the polymer exhibits a stress greater than 15 MPa at a strain of 5%. In some embodiments, the polymer exhibits a stress greater than 18 MPa at a strain of 5%. In some embodiments, the polymer exhibits a stress greater than 20 MPa at a strain of 5%. In some embodiments, the polymer exhibits a stress of 15-25 MPa at a strain of 5%. In some embodiments, the polymer additive comprises a polymer with a maximum strength greater than 20 MPa. In some embodiments, the polymer additive comprises a polymer with a maximum strength greater than 25 MPa. In some embodiments, the polymer additive comprises a polymer with a maximum strength greater than 30 MPa. In some embodiments, the polymer additive comprises a polymer with a maximum strength between 30 MPa and 35 MPa. In some embodiments, the polymer additive comprises a polymer with a maximum strength of approximately 33 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus greater than 5.5 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus greater than 7 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus greater than 7.5 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus of approximately 8 MPa.In some embodiments, the polymer additive comprises a polymer with a Young's modulus between 5.5 MPa and 10 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus between 7 MPa and 10 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus between 7 MPa and 8.5 MPa.

[0054] According to various embodiments, the electrode includes an active layer. In some embodiments, the active layer includes: (i) a network of high aspect ratio carbon elements defining void spaces within the network; (ii) a plurality of electrode active material particles disposed within the void spaces of the network; and (iii) a polymer additive. In some embodiments, the silicon contained in the active material particles comprises one or more of silicon oxide and microsilicon. In some embodiments, the polymer additive comprises one or more of polyolefins, polyacrylic acid, and styrene-butadiene rubber (SBR). In some embodiments, the high aspect ratio carbon element network defining the void spaces within the network comprises a first group of carbon nanotubes and a second group of carbon nanotubes. In some embodiments, the high aspect ratio carbon element network further comprises a third group of carbon elements. The third group of carbon elements may comprise graphite. The first group of carbon nanotubes comprises a plurality of first carbon nanotubes or a plurality of first carbon nanotube bundles. The second group of carbon nanotubes comprises a plurality of second carbon nanotubes or a plurality of second carbon nanotube bundles. The second group of carbon nanotubes has one or more properties different from those of the first group of carbon nanotubes. According to various embodiments, the first group of carbon nanotubes comprises multi-walled nanotubes, and the second group of carbon nanotubes comprises single-walled nanotubes. For example, the weight ratio of the first group of carbon nanotubes to the second group of carbon nanotubes is approximately 2:1. In some embodiments, the multi-walled carbon nanotubes have the following parameters: an average diameter of 6-10 nm; an average wall thickness of 6-7 nm; and an average length of 13-17 μm. In some embodiments, the average length of the multi-walled carbon nanotubes is approximately 13 μm. In some embodiments, the average length of the multi-walled carbon nanotubes is approximately 15 μm. In some embodiments, the average length of the multi-walled carbon nanotubes is approximately 16 μm. In some embodiments, the average diameter of the single-walled carbon nanotubes is between 1 nm and 2 nm, and the average length is approximately 5 μm. In some embodiments, the average diameter of the single-walled carbon nanotubes is between 3 nm and 5 nm, and the average length is between 7 and 8 μm.

[0055] According to various embodiments, the high aspect ratio carbon network contained in the electrode active layer is composed of a first group of carbon nanotubes and a second group of carbon nanotubes. The first group of carbon nanotubes comprises a plurality of first carbon nanotubes or a plurality of first carbon nanotube bundles. The second group of carbon nanotubes comprises a plurality of second carbon nanotubes or a plurality of second carbon nanotube bundles. The second group of carbon nanotubes has one or more properties different from those of the first group of carbon nanotubes. In some embodiments, the weight ratio of the first group of carbon nanotubes to the second group of carbon nanotubes is approximately 2:1. In some embodiments, the weight ratio of the first group of carbon nanotubes to the second group of carbon nanotubes is approximately 9:1. In some embodiments, the weight ratio of the first group of carbon nanotubes to the second group of carbon nanotubes is at least 5:1. In some embodiments, the weight ratio of the first group of carbon nanotubes to the second group of carbon nanotubes is at least 7:1.

[0056] In some embodiments, the high aspect ratio carbon network further includes a third group of carbon elements. This third group may include graphite. Graphite can be used to improve coulombic efficiency. Graphite is conductive and prevents expansion and deformation. In some embodiments, the active layer of the electrode comprises at least 5% graphite by weight. In some embodiments, the active layer of the electrode comprises approximately 5% graphite by weight. In some embodiments, the active layer of the electrode comprises at least 10% graphite by weight. In some embodiments, the active layer of the electrode comprises at least 15% graphite by weight. In some embodiments, the active layer of the electrode comprises at least 20% graphite by weight.

[0057] According to various embodiments, the electrode includes an active layer. In some embodiments, the active layer includes: (i) a network of high aspect ratio carbon elements defining void spaces within the network; (ii) a plurality of electrode active material particles disposed within the void spaces of the network; and (iii) a polymer additive soluble in at least one of (a) water or (b) an alcohol. The high aspect ratio carbon network defining the internal void structure may include a set of multi-walled carbon nanotubes. According to various embodiments, the length distribution of the set of multi-walled carbon nanotubes is biased towards the nominal length of the multi-walled carbon nanotubes. For example, breakage or fracture of the multi-walled carbon nanotubes can be reduced or minimized through specific processing and / or application methods. In a high aspect ratio carbon network, the length of the multi-walled carbon nanotubes is typically close to their nominal length or exhibits a more significant tendency to deviate towards the nominal length. In some embodiments, at least 75% of the multi-walled carbon nanotubes in the high aspect ratio carbon network have a length within ±10% of the nominal length (e.g., from 13.4 μm to about 15 μm). In some embodiments, at least 75% of the multi-walled carbon nanotubes in the high aspect ratio carbon network have a length of at least 12 micrometers. In some embodiments, at least 75% of the multi-walled carbon nanotubes in the high aspect ratio carbon network have a length of at least 13 micrometers. In some embodiments, at least 50% of the multi-walled carbon nanotubes in the high aspect ratio carbon network have a length within ±10% of the nominal length (e.g., from 13.4 micrometers to about 15 micrometers). In some embodiments, at least 50% of the multi-walled carbon nanotubes in the high aspect ratio carbon network have a length of at least 12 micrometers. In some embodiments, at least 50% of the multi-walled carbon nanotubes in the high aspect ratio carbon network have a length of at least 13 micrometers.

[0058] According to various embodiments, the electrode includes an active layer. In some embodiments, the active layer includes: (i) a network of high aspect ratio carbon elements defining void spaces within the network; (ii) a plurality of electrode active material particles disposed within the void spaces of the network; and (iii) a water- or alcohol-soluble polymer additive, wherein the adhesion of the active layer to the electrode foil is at least 75 N / m. In some embodiments, the adhesion of the active layer to the electrode foil is at least 90 N / m. In some embodiments, the adhesion of the active layer to the electrode foil is at least 100 N / m. In some embodiments, the adhesion of the active layer to the electrode foil is approximately 100 N / m. In some embodiments, the adhesion of the active layer to the electrode foil is at least 125 N / m. In some embodiments, the adhesion of the active layer to the electrode foil is at least 150 N / m. The high aspect ratio carbon element network may comprise multi-walled carbon nanotubes. The adhesion of the active layer to the electrode foil can be determined according to the peel test described in this application. In some embodiments, the foil comprises copper and / or a copper alloy. According to various embodiments, the foil can be coated on both sides (e.g., opposite sides). Coating both sides of the foil prevents folding of the foil during the drying process of the active layer (e.g., after the active layer is coated on the foil). For example, drying of the active layer causes it to shrink, thereby stressing the foil and causing corresponding folding / wrinkling. To avoid foil wrinkling, a thicker foil or coating on opposite sides of the foil can be used. In some embodiments, the foil (e.g., the thickness of the foil) depends at least in part on its tensile strength, which must be sufficient to withstand the forces exerted by the shrinkage of the active layer during drying and / or the forces generated by charge-discharge cycles (e.g., the forces generated by the expansion / contraction of silicon material during charge-discharge). In various embodiments, the thickness of the foil is less than 10 micrometers. In various embodiments, the thickness of the foil is less than 8 micrometers. In various embodiments, the thickness of the foil is less than 7 micrometers. In various embodiments, the thickness of the foil is less than 6 micrometers. In various embodiments, the thickness of the foil is less than 5 micrometers. In various embodiments, the thickness of the foil is approximately 6 micrometers.

[0059] According to various embodiments, the electrode includes an active layer. In some embodiments, the active layer includes: (i) a network of high aspect ratio carbon elements defining void spaces within the network; (ii) a plurality of electrode active material particles disposed within the void spaces of the network; and (iii) a water- or alcohol-soluble polymer additive, wherein the active layer does not crack when the electrode is wound around a mandrel with a diameter of at least 6 mm. The high aspect ratio carbon network may include multi-walled carbon nanotubes. In some embodiments, the determination of whether the active layer is cracked is based on visual observation of the active layer (e.g., the surface of the active layer). In some embodiments, visual observation of the active layer is performed by analyzing the electrode under a microscope. An example of a test method for detecting whether cracks have appeared in the active layer is as follows: the sample electrode is wound sequentially around a set of mandrels (e.g., from the smallest diameter to the largest diameter), the sample electrode is unfolded and the crack condition on both sides is observed, and then the above test is repeated using a mandrel with a larger diameter until no cracks are observed.

[0060] According to various embodiments, the electrode includes an active layer. In some embodiments, the active layer includes: (i) a network of high aspect ratio carbon elements defining void spaces within the network; (ii) a plurality of electrode active material particles disposed within the void spaces of the network; and (iii) a polymer additive processable in water or alcohol, wherein the active layer expands by less than 50% when immersed in an electrolyte. The polymer additive is soluble in water or alcohol. In some embodiments, the active layer expands by less than 40% when immersed in an electrolyte. In some embodiments, the active layer expands by less than 30% when immersed in an electrolyte. In some embodiments, the active layer expands by less than 10% when immersed in an electrolyte. In some embodiments, the active layer expands by less than 10% when immersed in an electrolyte. In some embodiments, the active layer expands by between 5% and 20% when immersed in an electrolyte. In some embodiments, the active layer expands by between 5% and 15% when immersed in an electrolyte. In some embodiments, the active layer expands by 5% to 10% when immersed in the electrolyte. The high aspect ratio carbon network may comprise multi-walled carbon nanotubes.

[0061] The "peel test" referred to in this application refers to a 90-degree peel test. A sample measuring 2.54 cm x 10 cm is used (e.g., an electrode with an active layer adhered to a foil). The peel test procedure includes: (i) cutting the double-sided positive electrode sample into 10 cm × 2.54 cm dimensions; (ii) attaching double-sided tape to one side and fixing it to the metal plate of the tester; one end of the transparent tape is fixed with a clamp, and the other end is flat against the electrode surface at a 90-degree angle; (iii) system zeroing: setting the motion mode to "cycle mode"; (iv) opening the test file named "sw-lx-v3", selecting the "com 5" port in the settings menu; (v) clicking "clear all data" in the left-hand menu list, setting the "sampling rate" to 0.2 seconds, selecting "continuous sampling", and starting the tester; (vi) selecting "stop sampling" in the left-hand menu list and terminating the tester operation; saving the file.

[0062] As used in this application, the term "high aspect ratio carbon element" refers to a carbon element whose size of one or more dimensions ("major dimensions") is significantly larger than the size of its lateral dimensions ("minor dimensions").

[0063] According to various embodiments, the electrode includes an active layer. In some embodiments, the active layer includes: (i) a network of high aspect ratio carbon elements defining void spaces within the network; (ii) a plurality of electrode active material particles disposed within the void spaces of the network, wherein the active material particles comprise silicon; and (iii) a polymer additive comprising a polymer material as described in U.S. Patent No. 8,124,277, the entire disclosure of which is hereby incorporated herein by reference for all purposes. In some embodiments, the silicon contained in the active material particles comprises one or more of silicon oxide and microsilicon. In some embodiments, the active material particles may comprise one or more of the following: graphite, hard carbon, activated carbon, nanocarbon, silicon, silicon oxide, and carbon-coated silicon nanoparticles. In some embodiments, the active layer of the electrode may be lithium-ion intercalated by a lithium-doping treatment, for example, using a pre-lithiation method known in the art.

[0064] Figure 1A This is a schematic diagram of an electrode according to various embodiments. In the illustrated example, an electrode 100 is provided. According to various embodiments, the electrode 100 includes a current collector 102 and an active layer 106. The electrode 100 may optionally include an adhesive layer 104. For example, the adhesive layer 104 is made of a material that promotes adhesion between the current collector 102 and the active layer 106.

[0065] In some embodiments, the current collector 102 is a conductive layer. For example, the current collector 102 may be a metal, a metal alloy, etc. As another example, the current collector 102 is a metal foil. In some embodiments, the current collector 102 is an aluminum foil or an aluminum alloy foil. In some embodiments, the current collector 102 is a copper foil or a copper alloy foil. The thickness of the current collector 102 is less than 15 µm. The thickness of the current collector 102 is less than 10 µm. The thickness of the current collector 102 is less than 8 µm. The thickness of the current collector 102 is less than 5 µm. The thickness of the current collector 102 is less than 15 µm. In some preferred embodiments, the thickness of the current collector 102 is between about 6 µm and about 8 µm. In some preferred embodiments, the thickness of the current collector 102 is between about 5 µm and about 8 µm. In some embodiments, the current collector 102 is an aluminum foil or an aluminum alloy foil with a thickness of about 6 µm. In some embodiments, the electrode comprises a foil with active layers on both opposite sides.

[0066] In some embodiments, the active layer 106 may comprise a three-dimensional network of high aspect ratio carbon elements 108 defining the void spaces within the network. Multiple active material particles 110 are distributed within the void spaces of the network. Therefore, the active material particles 110 are encapsulated or entangled by the network, thereby enhancing the cohesion of the active layer 106. In some embodiments, the three-dimensional network of high aspect ratio carbon elements 108 provides mechanical support for the active material particles 110.

[0067] According to various embodiments, the three-dimensional network of high aspect ratio carbon elements 108 comprises one or more of the following components: single-walled carbon nanotubes, multi-walled carbon nanotubes, a group of carbon nanotubes with fewer walls (e.g., fewer than 6 walls), and a group of carbon nanotubes with more walls (e.g., more than 6 walls), carbon nanostructures, single-walled carbon nanotube fragments, multi-walled carbon nanotube fragments, carbon nanostructure fragments, carbon black, etc. Other types of high aspect ratio carbon elements may also be used. The three-dimensional network of high aspect ratio carbon elements 108 maintains electrical connections between high aspect ratio carbon elements (such as carbon nanotubes) during electrode charge-discharge cycles. For example, when silicon particles in the active layer expand / contract during charge-discharge cycles, the three-dimensional network of high aspect ratio carbon elements 108 can maintain the electrical connections between these high aspect ratio carbon elements (such as carbon nanotubes). Multi-walled carbon nanotubes (or carbon nanotubes with more walls) can provide good encapsulation or coverage for silicon particles (such as silicon oxide) to accommodate silicon expansion (e.g., silicon particles can expand by approximately 300%). Single-walled carbon nanotubes (or carbon nanotubes with fewer walls) can expand along with silicon during charge / discharge cycles, so these types of carbon nanotubes generally do not reduce energy transfer efficiency.

[0068] According to various embodiments, the active layer 106 (e.g., a three-dimensional network of high aspect ratio carbon elements 108) comprises multi-walled carbon nanotubes or a group of carbon nanotubes with a large number of walls (e.g., more than 5 walls, or 5 layers of walls, etc.). In some embodiments, the content of multi-walled carbon nanotubes (or carbon nanotubes with a large number of walls) in the active layer 106 accounts for 2% to 5% of the weight of the active layer. In some embodiments, the content of multi-walled carbon nanotubes (or carbon nanotubes with a large number of walls) in the active layer 106 accounts for 3% to 5% of the weight of the active layer. In some embodiments, the content of multi-walled carbon nanotubes (or carbon nanotubes with a large number of walls) in the active layer 106 accounts for 3.75% to 5% of the weight of the active layer. In some embodiments, the content of multi-walled carbon nanotubes (or carbon nanotubes with a large number of walls) in the active layer 106 accounts for about 4% of the weight of the active layer.

[0069] The average thickness of the active layer 106 is between 10 micrometers and 200 micrometers. In some embodiments, the average thickness of the active layer 106 is between 15 micrometers and 50 micrometers. In some embodiments, the average thickness of the active layer 106 is between 10 micrometers and 25 micrometers. In some embodiments, the average thickness of the active layer 106 is approximately 100 micrometers. In some embodiments, the average thickness of the active layer 106 is approximately 50 micrometers. In some embodiments, the average thickness of the active layer 106 is between 25 micrometers and 50 micrometers. Typically, the active layer expands upon electrolyte wetting. Example methods for measuring the amount of expansion (e.g., expansion at least in the thickness direction) include: obtaining a sample electrode with a diameter of 1 inch (e.g., cutting a sample from a large electrode sheet using a 1-inch circular punch), measuring and recording the active layer thickness, placing the sample electrode inside a coin cell casing, injecting sample electrolyte, allowing the sample (including the injected electrolyte) to stand for 1 hour, measuring and recording the thickness after 1 hour, and then placing the electrolyte-wetted electrode in a drying chamber, covering it with a metal tray for 48 hours, and measuring and recording the electrode thickness after standing for 48 hours. According to various embodiments, the volume expansion (e.g., swelling) of the active layer 106 when immersed in the electrolyte is less than 10%. For example, the thickness of the active layer 106 after being immersed in the electrolyte is less than 110% of its thickness in the state without electrolyte. According to various embodiments, the volume expansion (e.g., swelling) of the active layer 106 when immersed in the electrolyte is less than 20%. For example, the thickness of the active layer 106 after being immersed in the electrolyte is less than 120% of its thickness in the state without electrolyte.

[0070] According to various embodiments, when the active layer 106 comprises multi-walled carbon nanotubes and single-walled carbon nanotubes, the expansion degree of the multi-walled carbon nanotubes when wetted with electrolyte in the energy storage device including the electrode 100 is greater than that of the single-walled carbon nanotubes. In some embodiments, the expansion degree of the multi-walled carbon nanotubes when wetted with electrolyte in the energy storage device including the electrode 100 is at least 15% higher than that of the single-walled carbon nanotubes. For example, when wetted with electrolyte, a segment of multi-walled carbon nanotube elongates at least 15% more than a single-walled carbon nanotube of the same length. In some embodiments, the expansion degree of the multi-walled carbon nanotubes when wetted with electrolyte in the energy storage device including the electrode 100 is at least 25% higher than that of the single-walled carbon nanotubes. For example, when wetted with electrolyte, a segment of multi-walled carbon nanotube elongates at least 25% more than a single-walled carbon nanotube of the same length. In some embodiments, the expansion degree of the multi-walled carbon nanotubes when wetted with electrolyte in the energy storage device including the electrode 100 is at least 50% higher than that of the single-walled carbon nanotubes. For example, when wetted with an electrolyte, a segment of multi-walled carbon nanotube can extend at least 50% more than a single-walled carbon nanotube of the same length. In some embodiments, the multi-walled carbon nanotube expands by up to 50% after wetting (e.g., the length of the multi-walled carbon nanotube increases by 50% after wetting with an electrolyte, and / or the diameter of the multi-walled carbon nanotube increases by 50% after wetting, etc.).

[0071] According to various embodiments, the three-dimensional network of high aspect ratio carbon element 108 comprises carbon nanotubes, wherein the carbon nanotubes are only multi-walled carbon nanotubes and / or carbon nanotube fragments. For example, the three-dimensional network of high aspect ratio carbon element 108 does not contain single-walled carbon nanotubes or single-walled carbon nanotube fragments. According to various embodiments, the three-dimensional network of high aspect ratio carbon element 108 comprises at least 99.9% (by weight) carbon. In some embodiments, the three-dimensional network of high aspect ratio carbon element 108 constitutes an electrically interconnected carbon element network with connectivity exceeding a percolation threshold, and the network defines one or more highly conductive pathways with a length greater than 100 µm. In some embodiments, the three-dimensional network of high aspect ratio carbon element 108 maintains electrical connectivity when silicon particles in the active layer expand or contract during charge-discharge cycles of electrode 100.

[0072] According to various embodiments, a network of high aspect ratio carbon elements defines the void spaces within the network, and the high aspect ratio carbon element network includes a first group of carbon nanotubes and a second group of carbon nanotubes. In some embodiments, the first group of carbon nanotubes includes multiple first carbon nanotubes or multiple bundles of first carbon nanotubes, and the second group of carbon nanotubes includes multiple second carbon nanotubes or multiple bundles of second carbon nanotubes. The second group of carbon nanotubes has one or more properties that are different from those of the first group of carbon nanotubes. For example, the number of layers (e.g., the number of walls) of the second group of carbon nanotubes is different from that of the first group of carbon nanotubes. In some embodiments, the first group of carbon nanotubes includes multi-walled carbon nanotubes. In some embodiments, the second group of carbon nanotubes includes single-walled carbon nanotubes. For example, the network of high aspect ratio carbon element 108 includes a group of multi-walled carbon nanotubes and a group of single-walled carbon nanotubes. The group of multi-walled carbon nanotubes may contain fragments of multi-walled carbon nanotubes, and / or the group of single-walled carbon nanotubes may contain fragments of multi-walled carbon nanotubes. According to various embodiments, the weight of multi-walled carbon nanotubes in the active layer is greater than that of single-walled carbon nanotubes. In some embodiments, the weight ratio of the first group of carbon nanotubes to the second group of carbon nanotubes in the active layer is approximately 1.5:1. In some embodiments, the weight ratio of the first group of carbon nanotubes to the second group of carbon nanotubes in the active layer is at least 1.5:1. In some embodiments, the weight ratio of the first group of carbon nanotubes to the second group of carbon nanotubes in the active layer is approximately 2:1. In some embodiments, the weight ratio of the first group of carbon nanotubes to the second group of carbon nanotubes in the active layer is at least 5:1. In some embodiments, the weight ratio of the first group of carbon nanotubes to the second group of carbon nanotubes in the active layer is approximately 9:1.

[0073] In existing energy storage devices, the carbon network comprises fragmented carbon nanotubes, such as fragmented multi-walled carbon nanotubes. In existing electrode manufacturing methods, for example, the fragmented multi-walled carbon nanotubes used in existing electrodes typically have an average length significantly shorter than the nominal length of the multi-walled carbon nanotubes (i.e., the original length of the carbon nanotube before entering the electrode manufacturing process—such as preparing or coating the active layer onto the current collector). The average length of the fragmented multi-walled carbon nanotubes in existing electrodes is typically significantly less than half the nominal length of the multi-walled carbon nanotubes. The average length of the fragmented multi-walled carbon nanotubes in existing electrodes is typically significantly less than one-third of the nominal length of the multi-walled carbon nanotubes. The manufacturing processes of existing electrodes are not gentle enough in handling the multi-walled carbon nanotubes or in preparing / manufacturing / coating the active layer, causing the multi-walled carbon nanotubes to break or fragment. Longer multi-walled carbon nanotubes typically provide better mechanical support for the active material particles within the active layer. For example, as the active material particles expand / contract during charge-discharge cycles, longer multi-walled carbon nanotubes can provide stronger mechanical support for the particles (e.g., the active material particles can form a tighter entanglement between relatively long multi-walled carbon nanotubes). Furthermore, longer multi-walled carbon nanotubes can form longer interconnect networks, where the highly conductive paths formed provide long conductive paths, facilitating current flow within and through the active layer (e.g., the size of the conductive paths can be on the order of the active layer thickness, such as...). Figure 1A The active layer 106 of the electrode 100 shown.

[0074] According to various embodiments, the electrode comprises multi-walled carbon nanotubes (MWCs) that are longer than those contained in prior art electrodes. It has been found that using relatively long MWCs in electrodes has beneficial mechanical and / or electrical properties. For example, MWCs can provide relatively good power performance at low densities. Another example is that shorter MWCs typically do not expand as significantly as longer MWCs. Therefore, using shorter MWCs results in the loss (or reduction) of some of the beneficial properties associated with carbon nanotube expansion. As an extreme example, carbon black does not expand because it is merely carbon particles and does not possess the entangled structure exhibited by a group of MWCs. One characterization of whether a specific amount of MWCs exceeds a threshold length to possess sufficient expansion properties can be observed in a calendering process—the relatively large pressure or force required to coat the slurry onto the foil indicates that the overall degree of expansion (e.g., average expansion rate) of the MWCs in the active layer will meet a specific performance threshold. However, MWCs are generally difficult to process. In the fabrication / formation of the active layer and / or electrode, the processing technology for multi-walled carbon nanotubes is gentler than that of prior art electrode processing technologies. Therefore, processes according to various embodiments can retain longer multi-walled carbon nanotubes (e.g., reducing crushing, fragmentation, breakage, etc.). In some embodiments, the active layer of the electrode comprises a set of multi-walled carbon nanotubes with an average length greater than the average length of multi-walled carbon nanotubes in prior art electrodes. According to various embodiments, the length distribution of the set of multi-walled carbon nanotubes is biased towards the nominal length of the multi-walled carbon nanotubes. For example, the nominal length of the multi-walled carbon nanotubes is approximately 16 micrometers. For example, breakage or fracture of the multi-walled carbon nanotubes can be reduced or minimized through specific processing and / or application methods. In high aspect ratio carbon networks, the length of the multi-walled carbon nanotubes is typically close to their nominal length or exhibits a more significant tendency to shift towards the nominal length. In some embodiments, at least 75% of the multi-walled carbon nanotubes in a high aspect ratio carbon network have a length within ±10% of the nominal length (e.g., from 13.4 micrometers to approximately 15 micrometers). In some embodiments, at least 75% of the multi-walled carbon nanotubes in the high aspect ratio carbon network have a length of at least 12 micrometers. In some embodiments, at least 75% of the multi-walled carbon nanotubes in the high aspect ratio carbon network have a length of at least 13 micrometers. In some embodiments, at least 50% of the multi-walled carbon nanotubes in the high aspect ratio carbon network have a length within ±10% of the nominal length (e.g., from 13.4 micrometers to about 15 micrometers). In some embodiments, at least 50% of the multi-walled carbon nanotubes in the high aspect ratio carbon network have a length of at least 12 micrometers. In some embodiments, at least 50% of the multi-walled carbon nanotubes in the high aspect ratio carbon network have a length of at least 8 micrometers.In some embodiments, at least 50% of the multi-walled carbon nanotubes in the high aspect ratio carbon network have a length of at least 13 micrometers. In some embodiments, at least 50% of the multi-walled carbon nanotubes in the high aspect ratio carbon network have a length within the range of ±50% of the nominal length (e.g., from 13.4 micrometers to about 15 micrometers). In some embodiments, at least 50% of the multi-walled carbon nanotubes in the high aspect ratio carbon network have a length within the range of ±60% of the nominal length (e.g., from 13.4 micrometers to about 15 micrometers). In some embodiments, at least 50% of the multi-walled carbon nanotubes in the high aspect ratio carbon network have a length within the range of ±75% of the nominal length (e.g., from 13.4 micrometers to about 15 micrometers). In some embodiments, the content of multi-walled carbon nanotubes with a length less than half the nominal length is less than 50% of the active layer weight. In some embodiments, the content of multi-walled carbon nanotubes with a length less than half the nominal length is less than 30% of the active layer weight. In some embodiments, the content of multi-walled carbon nanotubes with a length less than half the nominal length is less than 25% of the active layer weight.

[0075] The multi-walled carbon nanotubes (MWCNTs) contained in the electrode have an average higher aspect ratio (e.g., a longer length), which is superior to MWCNTs in prior art electrodes. A high-viscosity slurry is prepared and a low shear force is applied during processing to maintain the aspect ratio of the MWCNTs. In some embodiments, at least a portion of the MWCNTs contained in the active layer are branched carbon nanotubes. In some embodiments, at least a portion of the MWCNTs contained in the active layer exhibits a branched, interlocked, entangled, and / or shared-wall structure. The properties of the MWCNTs can be obtained by scanning electron microscopy (SEM). According to various embodiments, the average length of the MWCNTs is at least 5 micrometers. In some embodiments, the average length of the MWCNTs is at least 10 micrometers. According to various embodiments, the average length of the MWCNTs is between 10 and 15 micrometers. According to various embodiments, the average diameter of the MWCNTs is between 6 and 15 nanometers. In some embodiments, the average diameter of the MWCNTs is between 6 and 10 nanometers. According to various embodiments, the average number of MWCNT layers is between 3 and 15 layers. In some embodiments, the average number of multi-walled carbon nanotubes is between 3 and 15 layers. In some embodiments, the average number of multi-walled carbon nanotubes is between 5 and 10 layers. In some embodiments, the average number of multi-walled carbon nanotubes is between 6 and 7 layers. In some embodiments, the multi-walled carbon nanotubes contain an average of at least 6 layers. In some embodiments, the average aspect ratio of the multi-walled carbon nanotubes (e.g., a group of carbon nanotubes with a large number of walls) is at least 100. In some embodiments, the average aspect ratio of the multi-walled carbon nanotubes is between 200 and 1000. In some embodiments, high aspect ratio carbon elements may comprise sheet-like or plate-like elements having two primary dimensions and one secondary dimension. For example, in some such embodiments, the ratio of the length of each primary dimension to the length of the secondary dimension may be at least 5, 10, 100, 500, 1000, 5000, 10000, or higher.

[0076] According to various embodiments, the electrode comprises particles of a silicon-based active material. In some embodiments, the electrode comprises at least one material selected from silicon (e.g., microsilicon) and silicon oxide (e.g., SiO₂). x ), SiO x The electrode active material is a powder (Shin-Etsu 7131). Other types of silicon-based particles may also be used. In some embodiments, the active material comprises one or more of graphite, hard carbon, activated carbon, nano-carbon, silicon, silicon oxide, and carbon-coated silicon nanoparticles.

[0077] According to various embodiments, the plurality of active material particles 110 comprise microsilicon.

[0078] The active layer 106 contains a significant amount of active material particles. In some embodiments, the active layer 106 contains at least 50.0% active material particles by weight. In some embodiments, the active layer 106 contains 70.0% to 90.0% active material particles by weight. In some embodiments, the active layer 106 contains more than 80% active material particles by weight.

[0079] According to various embodiments, the active layer 106 comprises a polymer additive. This polymer additive can provide mechanical support for at least a portion of the plurality of active material particles 110 and / or at least a portion of the three-dimensional network of high aspect ratio carbon elements 108. For example, the polymer additive can bind to or adhere to the active material particles or carbon elements (such as carbon nanotubes, including multi-walled carbon nanotubes and / or single-walled carbon nanotubes). According to various embodiments, polymers with electrochemical stability have been found to have beneficial properties as polymer additives for the active layer 106. The polymer additive may be selected as a polymer that is completely soluble or highly soluble in the solvent used to process the electrode 100. For example, the polymer additive may be soluble in or highly soluble in alcohol solvents such as water or ethanol. In some embodiments, the polymer additive may be processed in water.

[0080] According to various embodiments, the polymer additive has relatively high tensile strength. For example, the polymer additive comprises a polymer that is not easily stretched. In some embodiments, the polymer additive has high tensile strength and can be processed in water or alcohol. In some embodiments, the polymer additive has high tensile strength and can be processed in water (e.g., it is relatively easy to process using water). In some embodiments, the polymer exhibits a stress greater than 20 MPa at a strain of about 10%. In some embodiments, the polymer exhibits a stress greater than 30 MPa at a strain of about 10%. In some embodiments, the polymer exhibits a stress of 30-35 MPa at a strain of about 10%. In some embodiments, the polymer exhibits a stress greater than 10 MPa at a strain of about 20%. In some embodiments, the polymer exhibits a stress greater than 20 MPa at a strain of about 20%. In some embodiments, the polymer exhibits a stress greater than 25 MPa at a strain of about 20%. In some embodiments, the polymer exhibits a stress of 25-30 MPa at a strain of about 20%. In some embodiments, the polymer exhibits a stress greater than 15 MPa at a strain of 5%. In some embodiments, the polymer exhibits a stress greater than 18 MPa at a strain of 5%. In some embodiments, the polymer exhibits a stress greater than 20 MPa at a strain of 5%. In some embodiments, the polymer exhibits a stress of 15-25 MPa at a strain of 5%. In some embodiments, the polymer additive comprises a polymer with a maximum strength greater than 20 MPa. In some embodiments, the polymer additive comprises a polymer with a maximum strength greater than 25 MPa. In some embodiments, the polymer additive comprises a polymer with a maximum strength greater than 30 MPa. In some embodiments, the polymer additive comprises a polymer with a maximum strength between 30 MPa and 35 MPa. In some embodiments, the polymer additive comprises a polymer with a maximum strength of approximately 33 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus greater than 5.5 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus greater than 7 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus greater than 7.5 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus of about 8 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus between 5.5 MPa and 10 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus between 7 MPa and 10 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus between 7 MPa and 8.5 MPa.

[0081] In some embodiments, the polymer additive comprises one or more of polyolefins, polyacrylic acid, and styrene-butadiene rubber (SBR). In some embodiments, the polymer additive comprises AquaChaige adhesive.

[0082] According to various embodiments, the electrode comprises 89 wt% Wacker microsilica powder, 1 wt% pre-dispersed Neocarbonix ethanol-based suspension of single-walled carbon nanotubes, and 10 wt% AquaCharge binder (10 wt% aqueous solution). AQUACHARGE is a trademark name for an aqueous binder for electrodes that utilizes water-soluble resin technology. AQUACHARGE is manufactured by Sumitomo Seika Co., Ltd., Hyogo Prefecture, Japan. A similar example can be found in U.S. Patent No. 8,124,277, entitled “Binder for Electrode Formation, Electrode Forming Slurry Using the Binder, Electrode Using the Slurry, Rechargeable Battery Using the Electrode, and Capacitor Using the Electrode,” the entire contents of which are incorporated herein by reference. Other examples include polyacrylic acid (PAA, a synthetic polymer of acrylic acid) and sodium polyacrylate (sodium salt of polyacrylic acid).

[0083] Existing electrodes typically employ polymer binders that are soluble only in toxic or environmentally harmful solvents. These polymer binders are used to disperse, adhere, and bind particles, and to maintain stability in harsh environments. The capacity of batteries in energy storage devices may gradually decrease after hundreds to thousands of charge-discharge cycles. Polymer binders help maintain the capacity stability of energy storage devices throughout their entire lifespan.

[0084] According to various embodiments, electrode 100 and / or active layer 106 do not include (e.g., are free from) polymer additives that are insoluble or cannot be processed in one or more alcohols such as water or ethanol. In some embodiments, the electrode is substantially free of polymer additives that are insoluble or cannot be processed in one or more alcohols such as water or ethanol. In some embodiments, electrode 100 and / or active layer 106 of electrode 100 do not include or are substantially free of polymer additives that are insoluble in one or more alcohols such as water or ethanol. For example, according to various embodiments, any polymer additive added to the electrode is soluble in one or more water and alcohol solvents (such as methanol, ethanol, etc.).

[0085] The polymer additive may be selected based at least in part on its reaction to a specific electrolyte used in the energy storage device containing electrode 100. In some embodiments, polymer additives with high (e.g., very high) molecular weights are selected because such polymer additives typically have good solvent resistance. For example, high molecular weight polymer additives do not dissolve in solvents, while low molecular weight polymers will form a paste. In some embodiments, polymers that do not soften when mixed with the electrolyte (e.g., soften to a degree below a softening threshold) are selected as polymer additives. In some embodiments, polymers that do not significantly expand when wetted / mixed with the electrolyte used in the energy storage device (e.g., expand or increase beyond a predefined expansion threshold) are selected as polymer additives.

[0086] The active layer 106 may comprise a polymer additive that is processable or soluble in water and / or alcohols such as ethanol. In some embodiments, the polymer additive has a high molecular weight. For example, the molecular weight of the polymer additive is greater than 200 g / mol. In some embodiments, the molecular weight of the polymer additive is greater than 400,000 g / mol. In some embodiments, the molecular weight of the polymer additive is greater than 500,000 g / mol. In some embodiments, the molecular weight of the polymer additive is greater than 1,000,000 g / mol. In some embodiments, the molecular weight of the polymer additive is between 500,000 g / mol and 1,500,000 g / mol.

[0087] The specific gravity of this polymer additive is between 1.0 g / cm³. 3 Up to 2.5 g / cm 3 Between. In some embodiments, the molecular weight of the polymer additive is greater than 1.135 g / cm³. 3 In some embodiments, the polymer additive has a molecular weight greater than 1.20 g / cm³. 3 The specific gravity of the polymer additive can be measured according to the ASTM D792 test method.

[0088] The specific heat capacity of the polymer additive at 23°C can be between 1.5 J / g°C and 3.5 J / g°C. In some embodiments, the specific heat capacity of the polymer additive at 23°C is greater than 2.0 J / g°C. In some embodiments, the specific heat capacity of the polymer additive at 23°C is greater than 2.2 J / g°C. In some embodiments, the specific heat capacity of the polymer additive at 23°C is approximately 2.4 J / g°C. The specific heat capacity of the polymer additive can be determined based on differential scanning calorimetry (DSC) measurements.

[0089] When the polymer additive is in a dry state, its tensile strength can be between 4 MPa and 100 MPa. For example, when the polymer additive is in a dry state, its tensile strength is between 4 MPa and 70 MPa. In some embodiments, the tensile strength of the polymer additive, measured when it is in a dry state, is less than 70 MPa. In some embodiments, the tensile strength of the polymer additive, measured when it is in a dry state, is less than 50 MPa. In some embodiments, the polymer exhibits a stress of 15-25 MPa at a strain of 5%. In some embodiments, the polymer additive comprises a polymer with a maximum strength greater than 20 MPa. In some embodiments, the polymer additive comprises a polymer with a maximum strength greater than 25 MPa. In some embodiments, the polymer additive comprises a polymer with a maximum strength greater than 30 MPa. In some embodiments, the polymer additive comprises a polymer with a maximum strength between 30 MPa and 35 MPa. In some embodiments, the polymer additive comprises a polymer with a maximum strength of approximately 33 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus greater than 5.5 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus greater than 7 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus greater than 7.5 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus of approximately 8 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus between 5.5 MPa and 10 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus between 7 MPa and 10 MPa. In some embodiments, the polymer additive comprises a polymer with a Young's modulus between 7 MPa and 8.5 MPa. The tensile strength of the polymer additive can be determined according to ASTM D638 test method.

[0090] The yield elongation of the polymer additive can be greater than 4%. For example, when measured in a dry state, the yield elongation is greater than 4% and less than 50%. In some embodiments, when measured in a dry state, the yield elongation is greater than 5%. In some embodiments, when measured in a dry state, the yield elongation is greater than 10%. In some embodiments, when measured in a dry state, the yield elongation is greater than 20%. In some embodiments, when measured in a dry state, the yield elongation is greater than 25%. In some embodiments, when measured in a dry state, the yield elongation is between 20% and 30%. The yield elongation of the polymer additive can be measured according to ASTM D638 test method.

[0091] According to various embodiments, the active layer 106 comprises a polymer additive selected from the polyamide family, or a modified polyamide or polyamide derivative. The polymer additive is soluble in water or alcohol solvents such as ethanol. In some embodiments, the polymer additive has a high molecular weight. The polymer additive at least partially fills at least one void space defined by a network structure composed of high aspect ratio carbon elements. In some embodiments, the polymer additive is used as a polymer binder. When the polymer additive is mixed with an ethyl cellulose solvent and cooled, the polymer additive may gel. For example, the polymer additive may be completely soluble in water, ethylene glycol, benzyl alcohol, acetic acid, and isobutanol. For example, the polymer additive may be completely soluble in N-methylpyrrolidone. The solubility of the polymer additive can be determined by adding 10 grams of the polymer additive to 100 ml of a specific solvent, stirring at 80°C for approximately 3 hours, cooling the mixture to room temperature after stirring, and then observing the state of the mixture.

[0092] Because the polymer additive provides mechanical support to the electrode 100 (e.g., mechanical support for the active material particles and / or carbon elements), the glass transition temperature of the selected polymer additive should generally be outside the operating temperature range of the energy storage device. In some embodiments, the glass transition temperature of the polymer additive is below 0°C. In some embodiments, the glass transition temperature of the polymer additive is below -10°C. In some embodiments, the glass transition temperature of the polymer additive is below -25°C. In some embodiments, the glass transition temperature of the polymer additive is below -30°C. In some embodiments, the glass transition temperature of the polymer additive is below -40°C. In some embodiments, the glass transition temperature of the polymer additive is below -45°C. In some embodiments, the glass transition temperature of the polymer additive is between -50°C and -40°C. The glass transition temperature of the polymer additive can be determined based on differential scanning calorimetry (DSC) measurements.

[0093] According to various embodiments, the 5% weight loss temperature of the polymer additive is between 375°C and 400°C. According to various embodiments, the 5% weight loss temperature of the polymer additive is approximately 385°C. A polymer additive may be selected that satisfies the following condition: when the concentration of the aqueous solution formed by the polymer additive with water and at least one of alcohols is approximately 50% (by weight), its viscosity reaches at least 60 Pa·s.

[0094] The active layer 106 may contain less than 5% polymer additives by weight of the active layer. In some embodiments, the amount of polymer material contained in the active layer 106 is approximately 8% by weight of the active layer. In some embodiments, the amount of polymer material contained in the active layer 106 is equal to or less than 8% by weight of the active layer. In some embodiments, the amount of polymer material contained in the active layer 106 is approximately 10% by weight of the active layer. In some embodiments, the amount of polymer material contained in the active layer 106 is equal to or less than 10% by weight of the active layer. In some embodiments, the amount of polymer material contained in the active layer 106 is less than 12% by weight of the active layer. In some embodiments, the amount of polymer material contained in the active layer 106 is less than 15% by weight of the active layer.

[0095] Examples of polymer additives include polyolefins, polyacrylic acid, styrene-butadiene rubber (SBR), polyethylene oxide (PEO), polyethers, polyethylene glycol (PEG) derivatives, fluoropolymers (especially polyvinylidene fluoride (PVDF)), polyurethane (PU), polytetrafluoroethylene (PTFE), alginate (Alg), refolded DNA / Alg, Alg-catechol complexes, PAA-catechol complexes, carboxymethyl chitosan, guar gum, agarose, konjac glucomannan, carboxymethyl gellan gum, PDA-PAA-PEO, pectin / polyacrylic acid complexes, partially lithium-ionized polyacrylic acid and perfluorosulfonic acid polymers, sequence-defined peptides, PMDOPA, branched polyacrylic acid, NaPAA-g-CMC, CS-g-PAANa, PVA-g-PAA, GC-g-LiPAA, PVDF-g-PAA, branched PAA-PEG, C S-g-PANI, hyperbranched β-cyclodextrin, double-helix natural xanthan gum, lithium-ionized perfluorosulfonic acid resin, PAA / CMC, cross-linked PAA / PVA, glycerol cross-linked polyPEDOT:PSS, maleic anhydride cross-linked corn starch, maleic anhydride cross-linked carboxymethyl cellulose, cross-linked natural guar gum polymer, cross-linked chitosan, chitosan-guar gum complex + glutaraldehyde cross-linking system, cross-linked dextrin, cross-linked carboxymethyl cellulose-polyethylene glycol complex, cross-linked hyperbranched polyethyleneimine, cross-linked polyacrylamide hydrogel, cross-linked polyurethane elastomer, cross-linked polyvinyl alcohol-polyvinylimine complex, trimethylolpropane functionalized polyvinyl alcohol network, polyamide-containing polymers (such as nylon), functionalized polyamides, copolymers of polyethylene oxide and polyamide, self-healing polymers, polyacrylic acid-ureidopyrimidinone supramolecular system, self-healing PAU-g-PEG, calcium ion cross-linked SA hydrogel, (Fe 3+ Crosslinking (PANa) 0.8 Fe y ), Sn 4+ Crosslinked PEDOT: PSS, PAA-PEG-PBI, crosslinked CMC-CPAM, metal polymers, Si@Fe3+ -PDA-PAA, β-CDp / 6 AD, slip ring PR-PAA, conductive PFFOMB, PEG-grafted PFP, PF-COONa, PFPQ-COONa, pyrene-based (PPyE), pyrene-based (PPyMAA), pyrene-based (PPyMADMA), PANI, FA-doped PEDOT:PSS, stretchable conductive adhesive, polyphenanthroline quinone, cyclized polyacrylonitrile, PAA-P (HEA-co-DMA), PEDOT:PSS / PEO / PEI, PAA / PVA + elastic gel polymer electrolyte, PAA + BFPU, mixtures of polyurethane and polyacrylic acid (PAA), copolymers of any subset thereof, etc. Zhao Yongming et al. (2021, Other polymers that can be used as polymer additives, Information Materials, Vol. 3, No. 5, pp. 460-501) described various polymers that can be used as polymer additives. The entire contents of this study are hereby included for all purposes.

[0096] In some embodiments, a surface treatment layer 202 (not shown, see FIG. 2) is coated on the surface of the high aspect ratio carbon element 108 of the network. This surface treatment layer promotes adhesion between the high aspect ratio carbon element and the active material particles 110. The surface treatment layer also promotes adhesion between the high aspect ratio carbon element and the current collector 102 (also referred to herein as the “conductive layer”), the optional adhesion layer 104, and / or at least a portion of the active material particles 110. The surface treatment layer may include a surfactant layer bonded to the high aspect ratio carbon element 108, the surfactant layer comprising a plurality of surfactant molecules, each surfactant molecule having a hydrophobic end and a hydrophilic end, wherein the hydrophobic end is disposed adjacent to the surface of the high aspect ratio carbon element 108, and the hydrophilic end is disposed away from the surface of the high aspect ratio carbon element 108. In some embodiments, the surface treatment layer 202 comprises at least a portion of a polymer additive. In some embodiments, the surface treatment layer comprises a material soluble in a solvent with a boiling point below 202°C. In some embodiments, the surface treatment layer comprises a material soluble in a solvent with a boiling point below 185°C.

[0097] In some embodiments, the surface treatment layer 202 may be composed of a carbonaceous material layer formed by the pyrolysis of a polymer material disposed on the surface of a high aspect ratio carbon element. This carbonaceous material layer (e.g., graphitic carbon or amorphous carbon) may adhere to the active material particles via covalent bonds or otherwise promote adhesion to the active material particles. Examples of suitable pyrolysis techniques are detailed in U.S. Patent Application No. 63 / 028,982, filed May 22, 2020. One of the polymer materials that can be used in this technique is polyacrylonitrile (PAN).

[0098] According to various embodiments, the active layer 106 comprises a dispersant. The dispersant may be selected based on its compatibility with alcohol solvents such as water and / or ethanol. In some embodiments, the dispersant is a water-soluble polymer. In some embodiments, the dispersant is an alcohol-soluble polymer. In some embodiments, the dispersant is a polymer that can be processed in water or alcohol. In some embodiments, the dispersant corresponds to or comprises polyvinylpyrrolidone (PVP). The PVP used in the dispersant may be a higher molecular weight PVP.

[0099] According to various embodiments, the active layer 106 comprises a dispersant comprising approximately 25% by weight of the active layer 106. In some embodiments, the amount of dispersant contained in the active layer 106 is between 10% and 50% by weight of the active layer 106. In some embodiments, the amount of dispersant contained in the active layer 106 is between 15% and 40% by weight of the active layer 106. In some embodiments, the amount of dispersant contained in the active layer 106 is between 20% and 30% by weight of the active layer 106.

[0100] Figure 1B This is a schematic diagram of an electrode according to various embodiments. In the illustrated example, an electrode 125 is provided. According to various embodiments, the electrode 125 includes a current collector 128 and an active layer 132. The electrode 125 may optionally include an adhesion layer 130. For example, the adhesion layer 130 is made of a material that promotes adhesion between the current collector 128 and the active layer 132. In some embodiments, the current collector 128 corresponds to (or is similar to) [the specific embodiment]. Figure 1A The current collector 102 in the middle.

[0101] In some embodiments, the active layer 132 corresponds to (or is similar to) Figure 1A The current active layer 106 is shown. According to various embodiments, the active layer of the electrode comprises a group of multi-walled carbon nanotubes (e.g., labeled 134 and shown as a solid line) and a group of single-walled carbon nanotubes (e.g., labeled 136 and shown as a dashed line). In some embodiments, the average aspect ratio of the multi-walled carbon nanotube group is greater than the average aspect ratio of the single-walled carbon nanotube group.

[0102] According to various embodiments, the active layer 132 comprises multi-walled carbon nanotubes and single-walled carbon nanotubes. In some embodiments, the amount of multi-walled carbon nanotubes in the active layer 132 is between 0.25% and 4% of the weight of the active layer. In some embodiments, the amount of single-walled carbon nanotubes in the active layer 136 is between 0.01% and 2% of the weight of the active layer. In some embodiments, the amount of single-walled carbon nanotubes in the active layer 136 is between 0.5% and 1.5% of the weight of the active layer. According to various embodiments, the weight ratio of multi-walled carbon nanotubes to single-walled carbon nanotubes in the active layer 132 is approximately 2:1. In some embodiments, the weight ratio of multi-walled carbon nanotubes to single-walled carbon nanotubes in the active layer 132 is approximately 5:1. In some embodiments, the weight ratio of multi-walled carbon nanotubes to single-walled carbon nanotubes in the active layer 132 is approximately 9:1. According to various embodiments, the weight ratio of multi-walled carbon nanotubes to single-walled carbon nanotubes in the active layer 132 is at least 7:1.

[0103] In some embodiments, the amount of multi-walled carbon nanotubes contained in the active layer 132 is between 0.25% and 5% of the weight of the active layer. In some embodiments, the amount of single-walled carbon nanotubes contained in the active layer 132 is between 0.01% and 2% of the weight of the active layer. In some embodiments, the amount of multi-walled carbon nanotubes contained in the active layer 132 is between 3% and 6% of the weight of the active layer. In some embodiments, the amount of multi-walled carbon nanotubes contained in the active layer 132 is between 3% and 5% of the weight of the active layer. In some embodiments, the amount of multi-walled carbon nanotubes contained in the active layer 132 is between 4% and 5% of the weight of the active layer. In some embodiments, the amount of multi-walled carbon nanotubes contained in the active layer 132 is approximately 4% of the weight of the active layer.

[0104] In some embodiments, the active layer 132 further comprises graphite. Graphite can be used to improve coulombic efficiency. Graphite is conductive and prevents expansion and deformation. In some embodiments, the active layer 132 of the electrode comprises at least 5% by weight of graphite. In some embodiments, the active layer 132 of the electrode comprises at least 4% to 7% by weight of graphite. In some embodiments, the active layer 132 of the electrode comprises about 5% by weight of graphite. In some embodiments, the active layer 132 of the electrode comprises at least 10% by weight of graphite. In some embodiments, the active layer 132 comprises at least 15% by weight of graphite. In some embodiments, the active layer 132 comprises at least 20% by weight of graphite.

[0105] The electrode contains single-walled carbon nanotubes with an average length greater than those in prior art electrodes. By preparing a high-viscosity slurry and applying low shear force during processing, the properties of multi-walled carbon nanotubes can be obtained using scanning electron microscopy (SEM). According to various embodiments, the length of the single-walled carbon nanotubes ranges from 1 nm to 34 nm. The average length of the single-walled carbon nanotubes can be between 7 μm and 8 μm. In some embodiments, the average diameter of the single-walled carbon nanotubes is between 1 nm and 2 nm, and the average length is approximately 5 μm. In some embodiments, the average diameter of the single-walled carbon nanotubes is between 3 nm and 5 nm, and the average length is at least 200 μm. In some embodiments, the average diameter of the single-walled carbon nanotubes is between 3 nm and 5 nm, and the average length is between 7 and 8 μm. In some embodiments, the average diameter of the single-walled carbon nanotubes is between 5 nm and 6 nm, and the average length is between 7 and 8 μm. In some embodiments, the average number of layers in the multi-walled carbon nanotubes is one or two.

[0106] Figure 1C This is a schematic diagram of an electrode according to various embodiments. In the example shown, the active layer of electrode 150 comprises functionalized carbon elements. For example, the functionalized carbon elements may be based at least on… Figure 1A The electrode 100 is obtained by treating the active layer 106 of the electrode with high aspect ratio carbon elements 108 (e.g., a group of multi-walled carbon nanotubes and / or a group of single-walled carbon nanotubes, etc.).

[0107] In some embodiments, the functionalized carbon elements are formed from a dried (e.g., freeze-dried) aqueous dispersion containing nano-sized carbon and functionalized materials (such as surfactants). In some such embodiments, the aqueous dispersion is substantially free of substances that could damage the carbon elements (such as acids).

[0108] In some embodiments, the surface-treated layer of high aspect ratio carbon elements includes a thin polymer layer disposed on the carbon elements, which promotes adhesion of the active material to the network. In some such embodiments, the thin polymer layer comprises a self-assembled and / or self-limiting polymer layer. In some embodiments, the thin polymer layer is bonded to the active material via hydrogen bonds or the like.

[0109] In some embodiments, the thickness of the thin polymer layer in the direction perpendicular to the outer surface of the carbon element may be less than 3 times, 2 times, 1 time, 0.5 times or 0.1 times (or less) the secondary size of the carbon element.

[0110] In some embodiments, the thin polymer layer contains functional groups (e.g., side-chain functional groups) that bind to the active material, for example, through 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 the carbon element.

[0111] In some embodiments, a thin polymer layer on certain elements may be bonded to a current collector or adhesive layer disposed thereon and below an active layer containing energy storage (i.e., active) material. For example, in some embodiments, the thin polymer layer contains side-chain functional groups that can be bonded to the surface of the current collector or adhesive layer via non-covalent bonding (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 the element. In some embodiments, this structure can provide the electrode with excellent mechanical stability.

[0112] In some embodiments, the polymeric material may be miscible with solvents of the types described in the examples above. For example, in some embodiments, the polymeric material may be miscible with solvents containing alcohols (such as methanol, ethanol, or 2-propanol (isopropanol, sometimes referred to as IPA)) or combinations thereof. In some embodiments, the solvent may contain one or more additives for further improving solvent properties, such as low-boiling-point additives (such as acetonitrile (ACN), deionized water, and tetrahydrofuran). In this example, the mixture is formed in an NMP-free solvent.

[0113] In a further exemplary embodiment, the surface treatment layer may consist of a carbonaceous material layer formed by the pyrolysis of a polymeric material disposed on the surface of a high aspect ratio carbon element. This carbonaceous material layer (e.g., graphitic carbon or amorphous carbon) may adhere to the active material particles via covalent bonds or otherwise facilitate adhesion to the active material particles. Examples of suitable pyrolysis techniques are detailed in U.S. Patent Application No. 63 / 028,982, filed May 22, 2020, the entire contents of which are incorporated herein by reference for all purposes. One of the polymeric materials that may be used in this technique is polyacrylonitrile (PAN).

[0114] According to various embodiments, the active layer 106 comprises a dispersant. The dispersant may be selected based on its compatibility with alcohol solvents such as water and / or ethanol. In some embodiments, the dispersant is a water-soluble polymer. In some embodiments, the dispersant corresponds to or comprises polyvinylpyrrolidone (PVP). The PVP used in the dispersant may be a higher molecular weight PVP.

[0115] Dispersants and additives can be added to the mixture. An example of a dispersant is PVP. Polyvinylpyrrolidone (PVP), also commonly known as "povidone" or "iodophor," is a water-soluble polymer made from the monomer N-vinylpyrrolidone. Dispersants typically act as emulsifiers and disintegrants in solution polymerization, and as surfactants, reducing agents, shape control agents, and dispersants in nanoparticle synthesis and their self-assembly. Another example of a dispersant is AQUACHARGE, a trademark name for a water-based adhesive for electrodes that utilizes water-soluble resin technology. AQUACHARGE is manufactured by Sumitomo Seika Co., Ltd., Hyogo Prefecture, Japan. A similar example can be found in U.S. Patent No. 8,124,277, entitled "An adhesive for electrode formation, an electrode formation slurry using the adhesive, an electrode using the slurry, a rechargeable battery using the electrode, and a capacitor using the electrode," the entire contents of which are incorporated herein by reference. Other examples include polyacrylic acid (PAA, a synthetic polymer of acrylic acid) and sodium polyacrylate (a sodium salt of polyacrylic acid). Table III Adding and mixing dispersants Table IV Target viscosity range of slurry

[0116] Figure 2 This is a schematic diagram of an electrode according to various embodiments. In the example shown, high aspect ratio carbon elements 201 (such as carbon 201) located near multiple active material particles 300 are shown in detail. Figure 1A and 1B The network structure 200 is shown. In the illustrated embodiment, the surface treatment layer 202 of element 201 is a surfactant layer bonded to the outer layer of the surface of element 201. As shown, the surfactant layer contains a plurality of surfactant molecules 210, each molecule having a hydrophobic end 211 and a hydrophilic end 212, wherein the hydrophobic end 211 is disposed adjacent to the surface of carbon element 201, while the hydrophilic end 212 is disposed away from the surface.

[0117] In some embodiments, when carbon element 201 is hydrophobic (as is typically a property of nano-carbon elements such as carbon nanotubes, carbon nanotube bundles, and graphene sheets), the hydrophobic end 211 of surfactant molecule 210 will be attracted by carbon element 201. Therefore, in some embodiments, surface treatment layer 202 can employ a self-assembled layer structure. For example, as described below, in some embodiments, when carbon element 201 and surfactant molecule 210 are mixed in a solvent to form a slurry, surface treatment layer 202 can self-assemble on the surface due to the electrostatic interaction between carbon element 201 and surfactant molecule 210 within the slurry.

[0118] In some embodiments, the surface treatment layer 202 is applied to the surface of a three-dimensional network of high aspect ratio carbon elements (e.g., Figure 1A The electrode 100 shown has a high aspect ratio carbon element 108. This surface treatment layer can promote the interaction of the high aspect ratio carbon element with the active material particles 300 (e.g., high aspect ratio carbon element 108). Figure 1A The adhesion between the active material particles 110 of the intermediate electrode 100. This surface treatment layer can also promote the adhesion between high aspect ratio carbon elements and the current collector (also referred to herein as the "conductive layer"), for example... Figure 1A The current collector 102 of the electrode 100 shown, and / or an optional adhesion layer (e.g. Figure 1A The adhesion layer 104 of the electrode 100 shown.

[0119] In some embodiments, the surface treatment layer 202 may be a self-limiting layer. For example, as described below, in some embodiments, when carbon element 201 and surfactant molecules 210 are mixed in a solvent to form a slurry, the surface treatment layer 202 can self-assemble on the surface due to the electrostatic interaction between carbon element 201 and surfactant molecules 210 within the slurry. In some such embodiments, once a region of the carbon element 201 surface is covered by surfactant molecules 210, other surfactant molecules 210 will not be attracted to that region. In some embodiments, once the carbon element 201 surface is covered by surfactant molecules 202, subsequent molecules are repelled by the layer, thus forming a self-limiting process. For example, in some embodiments, the surface treatment layer 202 can be formed by a self-limiting process, thereby ensuring that the layer remains extremely thin (e.g., at the single-molecule or multi-molecule level).

[0120] In some embodiments, at least a portion of the hydrophilic ends 212 of the surfactant molecules are bonded to the active material particles 300. Therefore, the surface treatment layer 202 can promote good adhesion between the carbon elements 201 of the network 200 and the active material particles. In some embodiments, this bonding can be covalent or non-covalent, such as π-π bonds, hydrogen bonds, electrostatic bonds, or combinations thereof.

[0121] For example, in some embodiments, the hydrophilic end 212 of the surfactant molecule 210 carries a first polarity charge; while the surface of the active material particle 300 carries a second polarity charge opposite to the first polarity, and thus they attract each other.

[0122] For example, in some embodiments, during the formation of layer 100, when the active material particles 300 are bonded to the carbon elements 201 with the surface treatment layer 202 in a solvent (as detailed below), the outer surface of the active material particles 300 may exhibit a Zeta potential opposite to that of the outer surface of the surface treatment layer 202 (as is known in the art). Therefore, in some such embodiments, the attractive force between the carbon elements 201 with the surface treatment layer 202 and the active material particles 300 promotes the self-assembly of the structure, causing the active material particles 300 to embed into the carbon elements 201 of the network 200.

[0123] In some embodiments, at least a portion of the hydrophilic ends 212 of the surfactant molecules are bonded to a current collector layer or adhesive layer beneath the active material layer. Therefore, the surface treatment layer 202 enables good adhesion between the carbon elements 201 of the network 200 and such an underlying layer. In some embodiments, this bonding can be covalent or non-covalent, such as π-π bonds, hydrogen bonds, electrostatic bonds, or combinations thereof. In some embodiments, as detailed below, this structure can provide excellent mechanical stability to the electrode 10.

[0124] In various embodiments, the surfactant used to form the surface treatment layer 202 described above may comprise any suitable material. For example, in some embodiments, the surfactant may comprise one or more of the following: hexadecyltrimethylhexafluorophosphate (CTAP), hexadecyltrimethyltetrafluoroborate (CTAB), hexadecyltrimethylacetate, hexadecyltrimethylnitrate, cocamidopropyl betaine, N-(cocoyl)-N,N,N-triisopropylmethylammonium sulfate, and cocamidopropyl betaine. Other suitable materials will be described below.

[0125] In some embodiments, the surfactant layer 202 can be formed by dissolving the compound in a solvent, such that the surfactant layer is composed of ions dissociated from the compound (e.g., formed by the self-confining process described above). In some such embodiments, the active layer 100 will contain residual counterions 214 corresponding to the surfactant ions constituting the surface treatment layer 202.

[0126] In some embodiments, these surfactant counterions 214 are selected to be suitable for the operating environment of the electrochemical cell. For example, in some embodiments, the counterions are selected to be ions that do not react or only slightly react with the materials used in the cell (such as electrolyte, separator, casing, etc.). For example, if an aluminum casing is used, the counterions may be selected to be ions that do not react or only slightly react with the aluminum casing.

[0127] For example, in some embodiments, the residual counterion contains no or substantially no halogen groups. For example, in some embodiments, the residual counterion contains no or substantially no bromine.

[0128] In some embodiments, the residual counterion may be selected from those compatible with the electrolyte used in the energy storage cell containing the active layer 200. For example, in some embodiments, the residual counterion may be the same type of ion used in the electrolyte itself. For example, if the electrolyte contains dissolved Li PF6 salt, then the electrolyte anion is PF6. In this case, a surfactant such as CTA PF6 may be selected, so that the anion layer generated by CTA PF6 forms the surface treatment layer 202, and the residual surfactant counterion is the PF6 anion in CTA PF6 (thus matching the electrolyte anion).

[0129] In some embodiments, the surfactant material used is soluble in solvents with excellent properties. For example, in some embodiments, the solvent may comprise water or alcohols (such as methanol, ethanol, or 2-propanol (isopropanol, sometimes referred to as IPA)) or combinations thereof. In some embodiments, the solvent may comprise one or more additives for further improving solvent properties, such as low-boiling-point additives (such as acetonitrile (ACN), deionized water, and tetrahydrofuran).

[0130] For example, if a low-boiling-point solvent is used when forming the surface treatment layer 202, the solvent can be quickly removed by using a thermal drying process (such as the type described in detail below) at a relatively low temperature. Those skilled in the art will understand that this can increase the manufacturing speed of the surface treatment layer 202 and / or reduce its manufacturing cost.

[0131] For example, in some embodiments, the surface treatment layer 202 is formed of a material that is soluble in solvents with boiling points below 250°C, 225°C, 202°C, 200°C, 185°C, 180°C, 175°C, 150°C, 125°C or lower (e.g., less than or equal to 100°C).

[0132] In some embodiments, the solvent may exhibit other beneficial properties. In some embodiments, the solvent may have low viscosity, for example, a viscosity at 20°C less than or equal to 3.0 centipoise, 2.5 centipoise, 2.0 centipoise, 1.5 centipoise, or lower. In some embodiments, the solvent may have low surface tension, for example, a surface tension at 20°C less than or equal to 40 mN / m, 35 mN / m, 30 mN / m, 25 mN / m, or lower. In some embodiments, the solvent may have low toxicity, for example, its toxicity may be comparable to that of alcohols such as isopropanol.

[0133] It is noteworthy that this contrasts with the traditional process for forming the active layer of an electrode using a monolithic binder material such as polyvinylidene fluoride (PVDF) or polyvinylidene fluoride (PVDF). These monolithic binders require solvents with strong dissolving power, typically exhibiting high boiling points, such as N-methyl-2-pyrrolidone (NMP). When using NMP (or other pyrrolidone solvents) as a solvent, a high-temperature drying process is required to remove the solvent. Furthermore, NMP is expensive, requires a complex solvent recovery system, and is highly toxic, posing significant safety hazards. In contrast, as further detailed below, in various embodiments, the active layer 200 can be formed without the use of NMP or similar compounds.

[0134] While an exemplary surface treatment layer 202 has been described above, it should be understood that other treatment layers may also be employed. For example, in various embodiments, the surface treatment layer 202 may be formed by functionalizing the high aspect ratio carbon element 201 using any suitable technique described herein or known in the art. Functional groups applied to element 201 may be selected to promote adhesion between the active material particles 300 and the network 200. For example, in various embodiments, the functional groups may include carboxyl, hydroxyl, amino, silyl, or combinations thereof.

[0135] As will be described in more detail below, in some embodiments, the functionalized carbon element 201 is formed from a dried (e.g., freeze-dried) aqueous dispersion containing nano-sized carbon and functionalized materials (such as surfactants). In some such embodiments, the aqueous dispersion is substantially free of substances (such as acids) that could damage the carbon element 201.

[0136] Figure 3 This is a schematic diagram of electrodes according to various implementation methods.

[0137] Reference Figure 3 In some embodiments, the surface treatment layer 202 on the high aspect ratio carbon element 201 comprises polymer particles disposed on the carbon element, which can promote the adhesion of the active material to the network. In some embodiments, the polymer particles comprise a self-assembled and / or self-limiting polymer layer. In some embodiments, the polymer particles are bonded to the active material via hydrogen bonds or other mechanisms.

[0138] In some embodiments, the polymer particles contain functional groups (e.g., side-chain functional groups) that bind to the active substance, for example, through non-covalent bonds (such as π-π bonds). In some such embodiments, the polymer particles may form a stable capping layer on at least a portion of the carbon element 201.

[0139] In some embodiments, polymer particles on certain carbon elements 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 polymer particles contain side-chain functional groups that are bonded to the surface of the current collector 101 or the adhesion layer 102 via non-covalent bonds (e.g., π-π bonds). In some such embodiments, the polymer particles may form a stable capping layer on at least a portion of the carbon elements 201. In some embodiments, as detailed below, this structure may provide excellent mechanical stability to the electrode 10.

[0140] In some embodiments, the polymeric material may be miscible with solvents of the types described in the examples above. For example, in some embodiments, the polymeric material may be miscible with solvents containing alcohols (such as methanol, ethanol, or 2-propanol (isopropanol, sometimes referred to as IPA)) or combinations thereof. In some embodiments, the solvent may contain one or more additives for further improving solvent properties, such as low-boiling-point additives (such as acetonitrile (ACN), deionized water, and tetrahydrofuran).

[0141] Suitable examples of materials that can be used for polymer particles include water-soluble polymers, such as polyvinylpyrrolidone.

[0142] Figure 4 Examples of electron microscope images of active layers according to various embodiments.

[0143] Reference Figure 4 An electron micrograph of a typical active material layer of the type described in this application. The image clearly shows vine-like high aspect ratio carbon elements (composed of carbon nanotube bundles) entwined between the active material particles. In some embodiments, there is no bulk polymer material occupying the space within the active layer.

[0144] Figure 5 This is a schematic diagram of an energy storage device.

[0145] Reference Figure 5 The energy storage cell 500 includes a first electrode 501, a second electrode 502, a permeable membrane 503 disposed between the first electrode 501 and the second electrode 502, and an electrolyte 504 impregnating the first electrode and the second electrode. One or both of electrodes 501 and 502 may be of the type described in this application.

[0146] In some embodiments, the energy storage cell 500 may be a battery, such as a lithium-ion battery. In some such embodiments, the electrolyte may be a lithium salt dissolved in a solvent, such as the type of electrolyte described in "Research Progress of Electrolytes for Rechargeable Lithium-Based Batteries and Other Batteries" published by Qi Li, Juner Chen, Lei Fan, Xueqian Kong, and Yingying Lu in Green Energy & Environment, Volume 1, Issue 1, pp. 18-42, the entire text of which is incorporated herein by reference.

[0147] In some such implementations, the operating voltage range of the energy storage cell may be 1.0V to 5.0V, or any subrange thereof (e.g., 2.3V to 4.3V).

[0148] In some such embodiments, the operating temperature range of the energy storage cell 500 may be -40°C to 100°C, or any sub-range thereof (e.g. -10°C to 60°C).

[0149] In some of these implementations, the energy storage cell 500 may have a weight 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.

[0150] In some of these implementations, the volumetric energy density of the energy storage cell 500 can reach 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.

[0151] In some such implementations, the C-rate of the energy storage cell 500 can range from 0.1 to 50.

[0152] In some such implementations, the energy storage cell 500 can 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.

[0153] In some embodiments, the energy storage cell 500 may be a lithium-ion capacitor of the type described in U.S. Patent Application No. 63 / 021492, filed May 8, 2020, the entire contents of which are incorporated herein by reference.

[0154] In some such embodiments, the operating temperature range of the energy storage cell 500 may be -60°C to 100°C, or any sub-range thereof (e.g. -40°C to 85°C).

[0155] In some of these implementations, the energy storage cell 500 can 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.

[0156] In some of these implementations, the volumetric energy density of the energy storage cell 500 can reach at least 20 Wh / L, 20 Wh / L, 40 Wh / L, 50 Wh / L, 60 Wh / L, 70 Wh / L, 80 Wh / L or higher.

[0157] In some of these implementations, the gravimetric energy density of the energy storage cell 500 can reach at least 5 kW / kg, 7.5 W / kg, 10 kW / kg, 12.5 kW / kg, 14 kW / kg, 15 kW / kg or higher.

[0158] In some of these implementations, the volumetric energy density of the energy storage cell 500 can reach 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.

[0159] In some such implementations, the C-rate of the energy storage cell 500 can range from 1.0 to 100.

[0160] In some such implementations, the energy storage cell 500 can have a cycle life of at least 100,000, 500,000, 1,000,000 or more charge-discharge cycles. Manufacturing method

[0161] As described in this application, it includes Figure 1A The electrode 100 with active layer 106 shown and the electrode 125 including active layer 132 shown in FIG1B can be manufactured using any suitable manufacturing process. Those skilled in the art will understand that, based on the teachings described herein and in conjunction with the wet coating technique described in International Patent Publication No. WO / 2018 / 102652 published on June 7, 2018, the electrode 10 can be prepared in some embodiments.

[0162] Figure 6 This is a flowchart illustrating electrode fabrication methods according to various implementation methods. (Combined with...) Figure 1A Electrode 100 provides a description of process 600. According to various embodiments disclosed herein, including... Figure 1B Electrode 125 can be processed similarly using process 600.

[0163] refer to Figure 6In some embodiments, process 600 may be used to form the active layer of the electrode (e.g., active layer 106 of electrode 100). Methods for manufacturing or processing the active layer and / or electrode are further described in U.S. Patent Application PCT / US2021 / 53519, filed October 5, 2021, the entire contents of which are hereby incorporated by reference for all purposes.

[0164] In step 610, high aspect ratio carbon element 201 and surface treatment material (such as surfactants or polymeric materials described herein) are combined with a solvent (of the type described herein) to form an initial slurry.

[0165] In step 620, 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 instrument, sometimes also referred to as an "ultrasonic device," or other suitable mixing equipment such as a high-shear mixer). In some embodiments, the mechanical energy introduced into the mixture is at least 0.4 kWh / kg, 0.5 kWh / kg, 0.6 kWh / kg, 0.7 kWh / kg, 0.8 kWh / kg, 0.9 kWh / kg, 1.0 kWh / kg, or higher. For example, the mechanical energy introduced per kilogram of mixture may 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.

[0166] In some implementations, an ultrasonic bath mixer may be used. In other implementations, a probe-type ultrasonic instrument may be used. When used for nanoparticles, probe-type ultrasound can be significantly more powerful and effective than an ultrasonic bath. The high shear forces generated by ultrasonic cavitation can break up particle agglomerates, resulting in smaller and more uniform particle sizes. Furthermore, ultrasonic treatment can also cause solids to form a stable and homogeneous suspension in a slurry. Typically, this leads to dispersion, deagglomeration, and other structural damage of solid particles. Examples of probe-type ultrasonic instruments include the Q-series probe-type ultrasonic instruments available from QSonica LLC in Newtown, Connecticut. Another example is the Branson Digital SFX-450 ultrasonic instrument, commercially available from Thomas Scientific in Switzboro, New Jersey.

[0167] However, in some implementations, the localized action of each probe within the probe assembly can lead to uneven mixing and suspension. This may occur, for example, with large-volume samples. This problem can be addressed by employing a device equipped with a continuous flow cell and appropriate mixing. For example, in such a configuration, the slurry mixing will achieve a fairly uniform dispersion.

[0168] In some embodiments, the viscosity of the treated initial slurry will be in the range of 5,000 to 25,000 centipoise or any sub-range thereof, such as 6,000 to 19,000 centipoise.

[0169] In step 630, a surface treatment layer 202 can be formed completely or partially on the high aspect ratio carbon element 201 in the initial slurry. In some embodiments, the surface treatment layer 202 at this stage can be as follows: Figure 2 and Figure 3 The self-assembly process is described in detail. The resulting surface treatment layer 201 may contain functional groups or other features that will promote adhesion between the high aspect ratio carbon element 201 and the active material particles 300 in subsequent steps.

[0170] In step 640, the active material particles 300 are mixed with the initial slurry to form a final slurry containing the active material particles 300 and the attached surface treatment layer 202 with high aspect ratio carbon elements 201.

[0171] In some embodiments, the active material 300 can be directly added to the initial slurry. In other embodiments, the active material 300 can be first dispersed in a solvent (e.g., using the aforementioned dispersion technique for the initial solvent) to form an active material slurry, and then this active material slurry can be mixed with the initial slurry to obtain the final slurry.

[0172] In step 650, the final slurry is treated to ensure good dispersion of the solid material. In various embodiments, any suitable mixing process known in the art can be used. In some embodiments, the treatment may be performed with reference to the technique described in step 620. In some embodiments, a planetary mixer, such as a multi-axis (three-axis or more-axis) planetary mixer, may be used. In some of these embodiments, such a planetary mixer may be equipped with multiple sets of blades, such as two or more mixing blades, and one or more (e.g., two, three, or more) dispersing blades (e.g., disc dispersing blades).

[0173] In some implementations, as described above Figure 2 and Figure 3 As detailed, in step 650, the substrate 200 encapsulating the active material 300 may fully or partially self-assemble. In some embodiments, the interaction between the surface treatment layer 202 and the active material 300 may facilitate the self-assembly process.

[0174] In some embodiments, the final viscosity of the treated slurry will be in the range of 1,000 to 10,000 centipoise or any sub-range thereof, such as 2,500 to 6,000 centipoise.

[0175] In step 660, the final slurry forms the active layer 106. In some embodiments, the final slurry can be directly wet-coated onto the current collector conductive layer 102 (or optionally the adhesion layer 104) and dried. For example, coating can be performed by at least one of heating and vacuuming until substantially all solvent and other liquids are removed, thereby forming the active layer 106. In such embodiments, it may be necessary to protect the underlying components. For example, if the electrode 100 is designed for double-sided operation, the bottom surface of the conductive layer 102 needs to be protected. For example, protection measures may include masking specific areas to prevent contact with the solvent, or providing flow-guiding structures to guide the solvent.

[0176] In other embodiments, any suitable technique (e.g., roll-to-roll lamination) may be used to first dry the final slurry at least partially in another location before transferring it onto the adhesive layer 104 or conductive layer 102 to form the active layer 106. In some embodiments, a wet mixed slurry may be placed on an intermediate material with a suitable surface and dried to form the layer (e.g., active layer 106). While any material with a suitable surface can be used as the intermediate material, exemplary intermediate materials include polytetrafluoroethylene (PTFE) due to its material properties that facilitate subsequent peeling from the surface. In some embodiments, the specified layer is formed by compression molding to obtain a layer with the desired thickness, area, and density.

[0177] In some embodiments, the final slurry can be sheeted and coated onto the adhesion layer 104 or the conductive layer 102 as needed. For example, in some embodiments, the thickness of the coated layer can be controlled by slot die coating. In other embodiments, the slurry can be smoothed to the desired thickness using a doctor blade after coating. A variety of other techniques can also be used for slurry coating. For example, coating techniques include, but are not limited to: comma coating; comma reverse coating; doctor blade coating; slot die coating; direct gravure coating; air knife coating; chamber doctor blade coating; transfer gravure coating; single-roll matching coating; small-diameter gravure roller reverse matching coating; rod coating; three-roll reverse coating (top feed); three-roll reverse coating (fountain die); reverse roller coating, etc.

[0178] Depending on the coating technique, the final slurry viscosity may vary. For example, comma coating has a viscosity range of approximately 1,000 to 200,000 centipoise. Lip die coating is suitable for slurries with viscosities of approximately 500 to 300,000 centipoise. Reverse coincidence coating is suitable for slurries with viscosities of approximately 5 to 1,000 centipoise. In some applications, the corresponding layers can be formed through multiple coatings.

[0179] In some embodiments, the active layer 106 formed from the final slurry may be compressed (e.g., using a calendering apparatus) before or after being applied to the electrode 100. In some embodiments, the slurry may be partially or completely dried (e.g., by heating, vacuuming, or a combination thereof) before or during the compression process. For example, in some embodiments, the active layer may be compressed to a final thickness (e.g., in a direction perpendicular to the current collector layer 102) that is less than 90%, 80%, 70%, 50%, 40%, 30%, 20%, 10%, or lower than its uncompressed thickness.

[0180] In various embodiments, when a partially dried layer is formed during coating or compression, the layer can then be completely dried (e.g., by heating, vacuuming, or a combination thereof). In some embodiments, substantially all solvent is removed from the active layer 106.

[0181] In some implementations, the solvent used to prepare the slurry is recovered and recycled for use in the slurry manufacturing process.

[0182] In some embodiments, the active layer 106 can be compressed, for example, by breaking down a portion of the high aspect ratio carbon elements or other carbonaceous materials, thereby increasing the surface area of ​​the layer. In some embodiments, this compression treatment can increase one or more of interlayer adhesion, intralayer ion transport rate, and / or layer surface area. In many embodiments, compression can be performed before or after the respective layer is applied to or formed on the electrode 100.

[0183] In some embodiments using calendered compression of the active layer 106, the gap spacing of the calendering apparatus can be set to be equal to or less than 90%, 80%, 70%, 50%, 40%, 30%, 20%, 10% or lower of the layer's uncompressed thickness (e.g., set to about 33% of the layer's uncompressed thickness). The calendering rolls can be configured to provide suitable pressure, for example, greater than 1 ton per centimeter roll length, greater than 1.5 tons per centimeter roll length, greater than 2.0 tons per centimeter roll length, greater than 2.5 tons per centimeter roll length, or higher. In some embodiments, the density of the compressed active layer will be in the range of 1 g / cc to 10 g / cc, or any sub-range thereof, for example, 2.5 g / cc to 4.0 g / cc. In some embodiments, the calendering process can be carried out in a temperature range of 20°C to 140°C, or any sub-range thereof. In some embodiments, the active layer 106 can be preheated before calendering, for example, in a temperature range of 20°C to 100°C, or any sub-range thereof.

[0184] Once the electrode 100 is assembled, it can be used to assemble an energy storage device. The assembly of the energy storage device can follow the conventional steps of assembling the electrode and the diaphragm and placing them in a housing (such as a tank or pouch), and may further include additional steps of adding electrolyte and sealing the housing.

[0185] In various embodiments, process 600 may include any of the following features (alone or in any suitable combination):

[0186] In some embodiments, the initial slurry has a solids content of 0.1% to 20.0% by weight (or any sub-range thereof). In some embodiments, the final slurry has a solids content of 10.0% to 80% by weight (or any sub-range thereof).

[0187] In various embodiments, the solvent used may be any of the solvents described herein for forming the surface treatment layer 202. In some embodiments, the surfactant material used to form the surface treatment layer 202 is soluble in a solvent with excellent properties. For example, in some embodiments, the solvent may comprise water or alcohols (such as methanol, ethanol, or 2-propanol (isopropanol, sometimes referred to as IPA)) or combinations thereof. In some embodiments, the solvent may comprise one or more additives for further improving solvent properties, such as low-boiling-point additives (such as acetonitrile (ACN), deionized water, and tetrahydrofuran).

[0188] In some embodiments, if a low-boiling-point solvent is used, the solvent can be rapidly removed by thermal drying at a lower temperature. Those skilled in the art will understand that this can increase the manufacturing speed of electrode 100 and / or reduce manufacturing costs. For example, in some embodiments, the boiling point of the solvent may be below 250°C, 225°C, 202°C, 200°C, 185°C, 180°C, 175°C, 150°C, 125°C, or lower, such as less than or equal to 100°C.

[0189] In some embodiments, the solvent may exhibit other beneficial properties. In some embodiments, the solvent may have low viscosity, for example, a viscosity at 20°C less than or equal to 3.0 centipoise, 2.5 centipoise, 2.0 centipoise, 1.5 centipoise, or lower. In some embodiments, the solvent may have low surface tension, for example, a surface tension at 20°C less than or equal to 40 mN / m, 35 mN / m, 30 mN / m, 25 mN / m, or lower. In some embodiments, the solvent may have low toxicity, for example, its toxicity may be comparable to that of alcohols such as isopropanol.

[0190] In some embodiments, during the formation of the active layer, the materials constituting the surface treatment layer are soluble in a solvent that is substantially free of pyrrolidone compounds. In some embodiments, the solvent is substantially free of N-methyl-2-pyrrolidone.

[0191] In some embodiments, the surface treatment layer 201 is formed of a material containing a surfactant of the type described in this application.

[0192] In some embodiments, high aspect ratio carbon elements and surface treatment materials are dispersed in a solvent to form an initial slurry, including applying force to cause the aggregated carbon elements to slide apart from each other in a direction perpendicular to their minor axis. In some embodiments, the technique for forming such dispersions can be referenced from the disclosure in International Patent Publication No. WO / 2018 / 102652, published on June 7, 2018, which is incorporated herein by reference in its entirety for all purposes based on the teachings herein.

[0193] In some embodiments, the high aspect ratio carbon element 201 may be functionalized prior to the formation of the slurry used to form the electrode 100. For example, one aspect of this application discloses a method 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 layer on the high aspect ratio carbon element; and drying the initial slurry to substantially remove all moisture, thereby obtaining a dry powder of the high aspect ratio carbon element having the surface treatment layer thereon. In some embodiments, the dry powder may be combined, for example, with a slurry of a solvent and an active material to form a final slurry of the type described above with reference to method 600.

[0194] In some embodiments, drying the initial slurry includes freeze-drying the initial slurry. In some embodiments, the aqueous solvent and the initial slurry are substantially free of substances that would damage the high aspect ratio carbon. In some embodiments, the aqueous solvent and the initial slurry are substantially free of acid. In some embodiments, the initial slurry is primarily composed of high aspect ratio carbon, surface treatment materials, and water.

[0195] Some embodiments further include: dispersing a dry powder of high aspect ratio carbon with surface treatment in a solvent, and adding an active material to form a secondary slurry; coating the secondary slurry onto a substrate; and drying the secondary slurry to form an electrode active layer. In some embodiments, the above steps may be performed using the technology disclosed in International Patent Publication No. WO / 2018 / 102652 published on June 7, 2018 (and based on the teachings herein).

[0196] In some embodiments, the final slurry may contain 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 pyrolyzing the additives, such that the surface treatment layer 202 can be formed as a carbonaceous material layer produced by the pyrolysis of the polymeric additives. This carbonaceous material layer (e.g., graphite or amorphous carbon) may adhere (e.g., via covalent bonds) to or otherwise promote adhesion to the active material particles 300. 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 / 028,982, filed May 22, 2020, which is hereby incorporated herein by reference in its entirety for all purposes. surfactants

[0197] The aforementioned techniques include using a surfactant to form a surface treatment layer 202 on the high aspect ratio carbon nanotubes 201 to promote adhesion to the active material particles 300. While several particularly suitable surfactants have been described, it should be understood that other surfactant materials, including the following types, may also be used.

[0198] Surfactants are surface-active molecules or groups, including wetting agents, dispersants, emulsifiers, detergents, and foaming agents. A variety of surfactants can be used to prepare surface treatment layers as described herein. Typically, the surfactants used contain lipophilic nonpolar hydrocarbon groups and polar functional hydrophilic groups. The polar functional groups can be carboxylates, esters, amines, amides, imides, hydroxyl groups, ethers, nitriles, phosphates, sulfates, or sulfonates. Surfactants can be used alone or in combination. Therefore, combinations of surfactants can include anionic, cationic, nonionic, zwitterionic, amphoteric, and facultative zwitterionic surfactants, provided that the head region of the surfactant molecular group has a net positive or net negative charge. In some cases, a single negatively or positively charged surfactant is used to prepare the electrode compositions of this application.

[0199] The surfactants used to prepare the electrode compositions of this application can be anionic, including but not limited to: sulfonates, such as alkyl sulfonates, alkylbenzene sulfonates, α-olefin sulfonates, paraffin sulfonates, and alkyl ester sulfonates; sulfates, such as alkyl sulfates, alkylalkoxy sulfates, and alkylalkoxylated sulfates; phosphates, such as monoalkyl phosphates and dialkyl phosphates; phosphonates; and carboxylates, such as fatty acids, alkylalkoxycarboxylates, sarcosine salts, hydroxyethanesulfonates, and taurine salts. Specific examples of carboxylates include sodium oleate, sodium cocoyl hydroxyethanesulfonate, sodium methyl oleoyl taurate, sodium lauryl ether carboxylate, sodium tridecyl ether carboxylate, sodium lauroyl sarcosinate, lauroyl sarcosinate, and sodium cocoyl sarcosinate. Specific examples of sulfates include sodium dodecyl sulfate (SDS), sodium lauryl sulfate, sodium lauryl ether sulfate, sodium tridecyl ether sulfate, sodium tridecyl sulfate, sodium cocoyl sulfate, and sodium monolaurate sulfate.

[0200] Suitable sulfonate surfactants include, but are not limited to, alkyl sulfonates, aryl sulfonates, monoalkyl and dialkyl sulfosuccinates, and monoalkyl and dialkyl sulfosuccinamides. Each alkyl group independently contains about 2 to 20 carbon atoms, and each alkyl group may also be ethoxylated to have an average of up to about 8 units (preferably up to about 6 units) of ethylene oxide, such as 2, 3, or 4 units. Exemplary examples of alkyl and aryl sulfonates are sodium tridecylbenzenesulfonate (STBS) and sodium dodecylbenzenesulfonate (SDBS).

[0201] Exemplary examples of sulfosuccinates include, but are not limited to: polydimethylsiloxane copolyol sulfosuccinate, pentyl sulfosuccinate, octyl sulfosuccinate, dicyclohexyl sulfosuccinate, diheptyl sulfosuccinate, dihexyl sulfosuccinate, diisobutyl sulfosuccinate, dioctyl sulfosuccinate, C12-15 alkylphenol polyether sulfosuccinate, cetearyl alcohol sulfosuccinate, cocoyl polydextrose sulfosuccinate, cocoyl butyl glucoside polyether-10 sulfosuccinate, decyl polyether-5 sulfosuccinate, decyl polyether-6 sulfosuccinate, dihydroxyethyl sulfosuccinoyl undecenoate, hydrogenated cottonseed oil glyceride sulfosuccinate, isodel sulfosuccinate, and isostearyl... Sodium sulfosuccinate, lanolin alcohol polyether-5 sulfosuccinate, lauryl alcohol polyether sulfosuccinate, lauryl alcohol polyether-12 sulfosuccinate, lauryl alcohol polyether-6 sulfosuccinate, lauryl alcohol polyether-9 sulfosuccinate, lauryl sulfosuccinate, nonylphenol polyether-10 sulfosuccinate, oleyl alcohol polyether-3 sulfosuccinate, oleyl sulfosuccinate, PEG-10 lauryl citrate sulfosuccinate, sitosterol polyether-14 sulfosuccinate, stearyl sulfosuccinate, tallow, tridecyl sulfosuccinate, sodium didecyl sulfosuccinate, diethylene glycol ricinoleate sulfosuccinate, di(1,3-dimethylbutyl) sulfosuccinate, and silicone copolyol sulfosuccinate.

[0202] Exemplary examples of sulfosuccinates include, but are not limited to: lauramide MEA sulfosuccinate, oleamide PEG-2 sulfosuccinate, cocamide MIPA sulfosuccinate, cocamide 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, oleamide PEG-2 Sulfosuccinate, palmamide PEG-2 sulfosuccinate, palm oleamide PEG-2 sulfosuccinate, PEG-4 cocoamide MIPA sulfosuccinate, castor oil oleamide MEA sulfosuccinate, stearamide MEA sulfosuccinate, stearyl sulfosuccinate, tallow oleamide MEA sulfosuccinate, tallow sulfosuccinate, undecyleneamide MEA sulfosuccinate, undecyleneamide PEG-2 sulfosuccinate, wheat germ amide MEA sulfosuccinate, and wheat germ amide PEG-2 sulfosuccinate.

[0203] Some examples of commercially available sulfonates are AEROSOL® OT-S, AEROSOL® OT-MSO, AEROSOL® TR70% (Cytec, West Paterson, New Jersey, USA), NaSul CA-HT3 (King Industries, Novak, Connecticut, USA), and C500 (Crompton, West Hill, Ontario, Canada). AEROSOL® OT-S is sodium dioctyl sulfosuccinate in petroleum fractions. 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 dinonylnaphthalene sulfonate / carboxylate complex. C500 is an oil-soluble calcium sulfonate.

[0204] Alkyl or alkyl group refers to a saturated hydrocarbon having one or more carbon atoms, including straight-chain alkyl (e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, etc.), cyclic alkyl (or cycloalkyl or alicyclic or carbocyclic) (e.g., cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, etc.), branched alkyl (e.g., isopropyl, tert-butyl, sec-butyl, isobutyl, etc.), and alkyl-substituted alkyl (e.g., alkyl-substituted cycloalkyl and cycloalkyl-substituted alkyl).

[0205] 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 thiocarbonyl, alkoxy, phosphate, phosphonate, hypophosphite, cyano, amino (including alkylamino, dialkylamino, arylamino, diarylamino and alkylarylamino), amide (including alkyl carbonylamino, aryl carbonylamino, carbamoyl and urea), imino, mercapto, alkylthio, arylthio, thiocarboxylate, sulfate, alkyl sulfinyl, sulfonate, aminosulfonyl, sulfonamide, nitro, trifluoromethyl, cyano, azide, heterocyclic, alkylaryl or aromatic (including heteroaromatic) groups.

[0206] In some embodiments, the substituted alkyl group may comprise a heterocyclic group. A heterocyclic group is a closed-ring structure similar to a carbide ring, wherein one or more carbon atoms in the ring are elements other than carbon, such as nitrogen, sulfur, or oxygen. The heterocyclic group may be saturated or unsaturated. Exemplary heterocyclic groups include aziridine, ethylene oxide (epoxide, oxetane), thiohexacyclopropane, dioxetane, azirone, oxetane, thiohexacyclobutane, dioxetane, dithiohexacyclobutane, dithiohexacyclobutene, azirone, pyrrolidine, dihydropyrrole, oxetane, dihydrofuran, and furan.

[0207] For anionic surfactants, the counterion is typically sodium, but can also be potassium, lithium, calcium, magnesium, ammonium, amines (primary, secondary, tertiary, or quaternary ammonium), or other organic bases. Exemplary amines include isopropylamine, ethanolamine, diethanolamine, and triethanolamine. Mixtures of the above-mentioned cations may also be used.

[0208] The surfactant used to prepare the materials of this application may 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 may be, for example, chlorides, bromides, methyl sulfates, ethyl sulfates, lactates, saccharin salts, acetates, and phosphates. Examples of cationic amines include polyethoxylated oleyl / stearyl amines, ethoxylated tallow amines, cocoyl alkyl amines, oleylamines, and tallow alkyl amines, and mixtures thereof.

[0209] Examples of quaternary ammonium salts having a single long alkyl group include: cetyltrimethylammonium bromide (CTAB), benzyldodecyldimethylammonium bromide (BddaBr), benzyldimethylhexadecylammonium chloride (BdhaCl), dodecyltrimethylammonium bromide, myristyltrimethylammonium bromide, stearyldimethylbenzylammonium chloride, oleyldimethylbenzylammonium chloride, lauryltrimethylammonium methyl methyl sulfate (also known as cocoa oil trimethylammonium methyl methyl sulfate), cetyldimethylhydroxyethylammonium phosphate dihydrogen phosphate, bassulamamide propylammonium chloride, cocoa oil trimethylammonium chloride, distearate dimethylammonium chloride, wheat germ amide propylammonium chloride, stearyl octyl dimethyl methyl ammonium sulfate, isostearamide propylammonium chloride, dihydroxypropyl PEG-5 linoleamide ammonium chloride, PEG-2 stearoyl ammonium chloride, behenyltrimethylammonium chloride, dicetyldimethylammonium chloride, tallow trimethylammonium chloride, and behenamide propyl ethyl dimethyl ethyl methyl ammonium sulfate.

[0210] Examples of quaternary ammonium salts having two long alkyl groups include: didodecyl dimethyl ammonium bromide (DDAB), distearyl dimethyl ammonium chloride, diceryl dimethyl ammonium chloride, stearyl octyl dimethyl ammonium methyl sulfate, dihydropalmitoyl ethyl hydroxyethyl ammonium methyl sulfate, dipalmitoyl ethyl hydroxyethyl ammonium methyl sulfate, dioleoyl ethyl hydroxyethyl ammonium methyl sulfate, and hydroxypropyl distearyl dimethyl ammonium chloride.

[0211] Quaternary ammonium compounds of imidazoline derivatives include, for example, isostearylbenzylimidazoline chloride, cocoylbenzylhydroxyethylimidazoline chloride, cocoylhydroxyethylimidazoline PG-chloride phosphate, and stearylhydroxyethylimidazoline chloride. Other heterocyclic quaternary ammonium compounds, such as dodecylpyridinium chloride, aminopropylline hydrochloride (AH), and benzylamine hydrochloride (BH), may also be used.

[0212] The surfactants used to prepare the materials of this application may be nonionic, including but not limited to: polyoxyalkylene carboxylate, fatty acid ester, fatty alcohol, ethoxylated fatty alcohol, poloxamer, alkanolamide, alkoxylated alkanolamide, polyethylene glycol monoalkyl ether, and alkyl polysaccharides. Polyoxyalkylene carboxylate has one or two carboxylate moieties, each moiety having about 8 to 20 carbons, and a polyoxyalkylene moiety containing about 5 to 200 alkylene oxide units. Ethoxylated fatty alcohol comprises an ethylene oxide moiety containing about 5 to 150 ethylene oxide units and a fatty alcohol moiety having about 6 to about 30 carbons. The fatty alcohol moiety may be cyclic, linear, or branched, saturated or unsaturated. Some examples of ethoxylated fatty alcohols include glycol ethers of oleyl alcohol, stearyl alcohol, lauryl alcohol, and isocetyl alcohol. Poloxamer is a block copolymer of ethylene oxide and propylene oxide, having about 15 to about 100 moles of ethylene oxide. Alkyl polysaccharide (“APS”) surfactants (e.g., alkyl polyglucosides) comprise a hydrophobic group having about 6 to about 30 carbons and a polysaccharide (e.g., polyglucosides) as a hydrophilic group. An example of a commercially available nonionic surfactant is FOA-5 (Octel Starreon LLC, Littleton, Colorado, USA).

[0213] 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 lauramide oxide, cocamidoamine oxide, cocamidopropylamine oxide, and lauramidepropylamine oxide; sorbitan laurate and sorbitan distearate; fatty acids or fatty acid esters, such as lauric acid, isostearic acid, and PEG-150 distearate; fatty alcohols or ethoxylated fatty alcohols, such as lauryl alcohol; and alkyl polyglucosides, such as decyl glucoside, lauryl glucoside, and cocoyl glucoside.

[0214] The surfactant used to prepare the materials of this application may be zwitterionic, having both positive and negative charges on the same molecule. The positively charged group may be quaternary ammonium, phosphonium, or sulfonium, while the negatively charged group may be carboxylate, sulfonate, sulfate, phosphate, or phosphonate. Similar to other classes of surfactants, the hydrophobic portion may contain one or more straight-chain, 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, cetyldimethylcarboxymethyl betaine, lauryl bis-(2-hydroxyethyl)carboxymethyl betaine, stearyl bis-(2-hydroxypropyl)carboxymethyl betaine, oleyldimethylγ-carboxypropyl betaine, and lauryl bis-(2-hydroxypropyl)α-carboxyethyl betaine; amamidopropyl betaine; and alkyl sulfonyl betaines, such as cocodimethylsulfonyl betaine, stearyldimethylsulfonyl betaine, lauryldimethylsulfonylethyl betaine, lauryl bis-(2-hydroxyethyl)sulfonyl betaine, and alkylamidopropylhydroxysulfonyl betaine.

[0215] The surfactant used to prepare the materials of this application may be amphoteric. Examples of suitable amphoteric surfactants include: ammonium salts or substituted ammonium salts of alkyl amphoteric carboxyglycinate and alkyl amphoteric carboxypropionate, alkyl amphoteric dipropionate, alkyl amphoteric diacetate, alkyl amphoteric glycinate, alkyl amphoteric propionate, and alkyl iminopropionate, alkyl imino dipropionate, and alkyl amphoteric propyl sulfonate. Specific examples are cocoamphoacetate, cocoamphopropionate, cocoamphodiacetate, lauryl amphoteric acetate, lauryl amphoteric diacetate, lauryl amphoteric dipropionate, lauryl amphoteric diacetate, cocoamphopropyl sulfonate, hexanoic acid amphoteric diacetate, hexanoic acid amphoteric dipropionate, and stearyl amphoteric acetate.

[0216] The surfactant used to prepare the materials of this application may also be a polymer, such as N-substituted polyisobutylene succinimide and succinate, alkyl methacrylate vinylpyrrolidone copolymer, alkyl methacrylate-dialkylaminoethyl methacrylate copolymer, alkyl methacrylate polyethylene glycol methacrylate copolymer, polystearamide and polyethyleneimine.

[0217] The surfactant used to prepare the materials of this application may 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).

[0218] The surfactant used to prepare the materials of this application 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.

[0219] The surfactant used to prepare the materials of this application may be a combination of two or more surfactants of the same or different types, wherein the type is selected from anionic, cationic, nonionic, amphoteric, facultative, and zwitterionic 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 zwitterionic surfactants, mixtures of three zwitterionic surfactants, mixtures of four zwitterionic surfactants; mixtures of two zwitterionic surfactants, mixtures of three zwitterionic surfactants, mixtures of four zwitterionic surfactants; mixtures of two facultative zwitterionic surfactants, mixtures of three zwitterionic surfactants, and mixtures of four facultative zwitterionic surfactants. polymer particles

[0220] The aforementioned techniques include using a polymer to form a surface treatment layer 201 on high aspect ratio carbon nanotubes to promote adhesion to the active material particles 300. While several particularly suitable polymers have been described, it should be understood that other polymeric materials, including the following types, may also be used.

[0221] The polymer used to prepare the materials of this application can be a polymeric material, such as a water-processable polymeric material and / or an alcohol-processable polymeric material. In various embodiments, any of the following polymers (and combinations thereof) 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 hybrid latex (TRD202A), provided by JSR Corporation.

[0222] Figure 7This is a schematic diagram of a pouch cell battery.

[0223] According to various embodiments, the teachings of this document provide electrodes free of PVDF binders in the positive electrode and free of other conventional binders in the negative electrode. Instead, as detailed above, a three-dimensional carbon scaffold or matrix binds the active material particles together to form a cohesive layer that also adheres firmly to the metal current collector. This active material structure is formed during slurry preparation and subsequently finalized in a roll-to-roll (“R2R”) coating and drying process. One of the key advantages of this technology is its scalability and “plug-and-play” nature, as various embodiments are compatible with conventional electrode manufacturing processes.

[0224] The three-dimensional carbon matrix is ​​formed during slurry preparation using the techniques described herein: high aspect ratio carbon materials are appropriately dispersed and chemically functionalized, for example, using a two-step slurry preparation process (as described above). Figure 6 The process described in process 600 is of the type described above. The chemical functionalization aims to form an organized self-assembled structure with the surface of the active material particles, such as NMC particles for the positive electrode or silicon particles (“Si”) or silicon oxide (“SiO”) for the negative electrode. x The resulting slurry can be used for the positive electrode based on water and / or alcohol solvents, and for the negative electrode based on water. These solvents are very easy to evaporate and handle during the manufacturing process. Electrostatic interactions promote self-organized structures in the slurry, and after the drying process, the bonding between the carbon matrix thus formed and the active material particles and the current collector surface is promoted through surface treatment layers (e.g., functional groups on the matrix) and the strong entanglement of the active material in the carbon matrix.

[0225] As those skilled in the art will understand, the mechanical properties of the electrode can be easily adjusted by adjusting the balance between surface functionalization and entanglement effect, depending on the application and the required active material loading per unit area.

[0226] After coating and drying, the electrode undergoes a calendering step to control the density and porosity of the active material. In NMC cathode electrodes, densities of 3.5 g / cc or higher and porosities of 20% or higher can be achieved. Porosity can be optimized based on the load per unit area and lithium-ion cell requirements. For SiO2... x / Si anode, the porosity is specifically controlled to accommodate the expansion of the active material during the lithiation process.

[0227] In some typical applications, the teachings in this paper can reduce the cost per kilowatt-hour by up to 20%. Electrode production is more efficient by using readily evaporating, environmentally friendly solvents, and more importantly, energy consumption from lengthy drying processes is significantly reduced. Traditional NMP recovery systems are also greatly simplified when using alcohols or other solvent mixtures.

[0228] This paper teaches a three-dimensional matrix that can significantly improve electrode conductivity by 10 to 100 times compared to electrodes using conventional binders such as PVDF, thereby enabling fast charging at the battery level. This technology allows for thick-coated positive electrodes with a single-sided coating thickness of up to 150 micrometers (or more). The solvent used in the slurry, combined with a robust three-dimensional carbon matrix, is designed to achieve a thick wet coating that does not crack during the drying process. The combination of a high-capacity negative electrode and a thick positive electrode results in a significant leap in energy density, reaching 400 Wh / kg or higher.

[0229] Fast charging is achieved through an alloying process (Si / SiO). x This is achieved by using a high-capacity negative electrode for lithiation, and by reducing the overall cell impedance when combining positive and negative electrodes as described in this paper. The teachings of this paper enable fast charging by providing highly conductive electrodes, particularly highly conductive positive electrodes.

[0230] One exemplary embodiment includes a lithium-ion battery energy storage device using a pouch cell, wherein the positive electrode uses a nickel-rich NMC active material and the negative electrode uses SiO2. x The active material is a mixture of graphite and other materials, wherein both the positive and negative electrodes are made using the three-dimensional carbon matrix process described herein.

[0231] A schematic diagram of a pouch cell device with electrode arrangement is shown below. Figure 7 As shown, a double-sided positive electrode 700 (using a positive electrode layer 760 (e.g., an active layer according to various embodiments disclosed herein)) is positioned between two single-sided negative electrodes 720 and 730, each negative electrode having a negative electrode layer 740 and 750 disposed on a copper foil current collector (e.g., an active layer comprising a carbon network as disclosed herein). The electrodes are separated by a porous membrane material (not shown) permeated with electrolyte (not shown). This structure can be accommodated within a pouch cell housing well known in the art.

[0232] These devices may have the following characteristics: high areal loading of nickel-rich NMC cathode electrodes and their manufacturing methods: areal loading = 20-30 mg / cm² 2 Specific capacity >210mAh / g. Based on SiO x / Graphite anode (SiO) x Electrode and its material synthesis and manufacturing method with a content ≈ 20 wt.% (electrode content ≈ 20 wt.%): area loading 8-14 mg / cm² 2 Reversible specific capacity ≥ 550mAh / g. Specifically designed for SiO₂. x Long-term performance of electrolytes in graphite anode-based lithium-ion battery designs: operating temperature range -30 to 60°C. High energy density and long cycle life of nickel-rich NMC cathode / SiO₂.x + Graphite / carbon+ based lithium-ion battery pouch cells: capacity ≥ 5 Ah, specific energy ≥ 300 Wh / kg, energy density ≥ 800 Wh / L, cycle life exceeding 500 cycles at 1C charge / discharge rate, and ultra-high power fast charge / discharge rate capability (up to 5C rate).

[0233] Figure 8 This is a cross-sectional schematic diagram showing part of the structure of an energy storage device (ESD).

[0234] Generally, the energy storage (ESD) examples disclosed herein are illustrative. That is, energy storage (ESD) devices are not limited to the embodiments disclosed herein.

[0235] More specific examples of energy storage devices (ESD) include supercapacitors such as electric double-layer capacitors (devices that store charge electrostatically), pseudocapacitors (devices that store charge electrochemically), and hybrid capacitors (devices that store charge electrostatically and electrochemically). Typically, electrostatic double-layer capacitors (EDLCs) use carbon electrodes or their derivatives, whose electrostatic double-layer capacitance is much higher than that of electrochemical pseudocapacitance, achieved through charge separation via the Helmholtz double layer at the interface between the conductive electrode surface and the electrolyte. Electrochemical pseudocapacitors typically use metal oxide or conductive polymer electrodes, exhibiting significant electrochemical pseudocapacitance in addition to double-layer capacitance. Pseudocapacitance is achieved through Faraday electron charge transfer accompanying redox reactions, intercalation, or electroadsorption. Hybrid capacitors, such as lithium-ion capacitors, use electrodes with different characteristics: one primarily exhibiting electrostatic capacitance, and the other primarily exhibiting electrochemical capacitance.

[0236] Other examples of energy storage devices (ESD) include rechargeable batteries, accumulators, or secondary batteries, which are battery types that can be charged, discharged to a load, and recharged multiple times. During charging, the positive electrode active material is oxidized, generating electrons, while the negative electrode material is reduced, consuming electrons. These electrons constitute the current in the external circuit. Typically, the electrolyte acts as a buffer medium for the internal ion flow between the electrodes (e.g., the negative and positive electrodes). Battery charging and discharging rates are usually discussed using a “C” rate of reference current. The C rate refers to the current that theoretically allows the battery to be fully charged or discharged within one hour. “Depth of Discharge” (DOD) is typically expressed as a percentage of the nominal ampere-hour capacity. For example, zero percent (0%) DOD means no discharge.

[0237] exist Figure 8The image shows a cross-sectional view of an energy storage device (ESD) 810. The energy storage device (ESD) 810 includes a housing 811. Two terminals 800 are provided on the exterior of the housing 811. The terminals 800 provide internal electrical connections to the energy storage cells 812 housed within the housing 811, and external electrical connections to external devices (such as loads or charging devices, not shown).

[0238] Figure 9 yes Figure 8 A cross-sectional schematic diagram of a conventional energy storage cell for medium-energy storage devices (ESD).

[0239] Figure 9 A cross-sectional view of the energy storage cell 912 is depicted. As shown, the energy storage cell 912 comprises multiple layers of wound energy storage material. That is, sheet-like or strip-like energy storage material is wound together to form a rolled structure. The wound energy storage material includes opposing electrodes, referred to as "negative electrode 930" and "positive electrode 940". The negative electrode 930 and positive electrode 940 are separated by a separator 950. An electrolyte, not shown in the figure but part of the energy storage cell 912, is also present. Typically, the electrolyte permeates or wets the positive electrode 940 and negative electrode 930, and promotes ion migration within the energy storage cell 912. According to various embodiments, the positive electrode 940 corresponds to or is similar to... Figure 1A Electrode 100, or Figure 1B Electrode 125. In some embodiments, positive electrode 940 corresponds to an electrode comprising a high aspect ratio carbon network disclosed herein and / or polymer additives disclosed herein.

[0240] Figures 10 to 19 This is a schematic diagram of the electrical performance of an energy storage cell assembled according to various implementation methods.

[0241] Figure 10 The C-rate diagram of a half-cell constructed according to the technical solution of this application is shown. The areal loading of NCM active material in this half-cell is 22.5 mg / cm². 2 In this example, the "Best Process" curve represents a binderless electrode manufactured according to the teachings of this document. The "Older Process" curve represents a binderless electrode manufactured without the surfactants and dispersants disclosed herein. The "PVDF" curve represents cell performance using electrodes manufactured with existing technology. In this example, the half-cell employs a pouch cell structure. The table below provides the initial specific capacity and C-rate test results. The working electrode size is 45x45 mm, and the lithium counter electrode size is 46x46 mm. The electrolyte is 1M LiPF6, and the solvent is EC / DMC (volume ratio 1:1) containing 1% VC. Figure 10 data:

[0242] exist Figure 11The paper presents test results for a complete pouch cell. In this example, the positive electrode is nickel-rich NMC, measuring 45 x 45 mm; the negative electrode is a graphite electrode, measuring 46 x 46 mm. The electrolyte is 1 M LiPF6, with EC / DMC (volume ratio 1:1) and 1% VC as the solvent. The N / P ratio is ~1.1. It can be seen that its hybrid pulsed power characteristic (HPPC) resistance is significantly lower than that of the traditional PVDF process. As shown in the figure, the positive electrode prepared according to the teachings of this paper exhibits lower charging resistance, thus achieving superior performance at a 10% charge state. Figure 13 The results show that cycle stability is improved by manufacturing the positive electrode according to the teachings of this paper.

[0243] Another pouch cell was constructed for testing. In this embodiment, the cathode was nickel-rich NMC, with dimensions of 45 x 45 mm and an areal loading of 28-30 mg / cm². 2 The negative electrode uses graphite / SiO2. x (SiO) x Composite electrode (45% purity), size 46x46mm, mass loading 8-9mg / cm³ 2 The electrolyte is 1.1M LiPF6, with a solvent composition of PC:FEC:EMC:DEC = 20:10:50:20. The negative / positive electrode capacity ratio (N / P) is approximately 1.04 to 1.10. The cathode is composed of NMC and 45% SiO2. x The negative electrode is manufactured using the process described herein, employing a mixture of surfactants and dispersants combined with a three-dimensional nano-carbon matrix (e.g., NX electrode). The specific energy of this lithium-ion battery cell is approximately 332 Wh / kg (with a pouch cell packaging efficiency of 90%), which can reach 351 Wh / kg if the packaging efficiency is increased to 95%. The energy density is approximately 808 Wh / L (based on 90% packaging efficiency and 10% pouch volume expansion), which can reach approximately 853 Wh / L if the packaging efficiency is increased to 95% (with the volume expansion rate remaining at 10%). Based on the proposed electrode manufacturing process, the initial charge specific capacity of the positive and negative electrodes is approximately 228 mAh / g and 852 mAh / g, respectively; the initial discharge specific capacity is approximately 210 mAh / g and 750 mAh / g, respectively. In this example, the initial charge capacity of the lithium-ion battery cell is 240 mAh, and the initial discharge capacity at a 0.1C constant current charge / discharge rate and a voltage range of 4.2V to 2.5V is 216 mAh. The initial coulombic efficiency is approximately 90%. Some data and electrical performance characteristics of the battery cell are as follows: Figures 15 to 19 As shown.

[0244] The characteristics of an example cell using the fabricated electrodes are shown in the table below. Furthermore, this example cell did not exhibit cracking or stress problems commonly seen in certain physical tests.

[0245] Figure 20 An example cell using the electrodes described herein (e.g., NX electrodes) is shown. The cell dimensions are approximately 46.5 mm x 48.5 mm x 7.14 mm. Figure 20 The battery cell shown corresponds to a 1.5-3.5Ah battery cell. The illustrated cell (e.g., with NX NMC811 electrodes) has an initial charge specific capacity greater than or equal to 210mAh / g and an areal capacity of approximately 5.6mAh / cm². 2 .

[0246] Figure 21 Another example cell using the electrodes described herein (e.g., an NX electrode comprising a three-dimensional carbon nanofiber matrix) is shown. The cell measures approximately 62 mm x 107 mm x 5.4 mm. Figure 21 The battery cell shown corresponds to a 9.0-12.0 Ah battery cell. The illustrated cell (e.g., with NX NMC811 electrodes) has an initial charge specific capacity greater than or equal to 1116 mAh / g and an areal capacity of approximately 6.5 mAh / cm². 2 .

[0247] Figure 22 Performance graphs are presented for various cell examples (e.g., pouch cells). These cells are approximately 46 mm x 46 mm x 3 mm in size. For a cell containing 9 layers of NMC811 positive electrode and 10 layers of silicon negative electrode (e.g., a 1.5 Ah cell), the packaging efficiency is approximately 86%; however, in larger pouch cells with capacities greater than 5 Ah and more layers, the packaging efficiency can be increased to 95%. The results indicate that, for the same small pouch cell specifications and number of layers, the silicon negative electrode (5.5-5.0 mg / cm³) achieves significantly higher efficiency. 2 Compared to graphite anodes (16 mg / cm³), 2 To match 24mg / cm 2 The NX NMC811 cathode can increase the specific energy by at least 30% and improve the energy density.

[0248] Figure 23 A performance comparison chart is shown, illustrating the interaction between a battery cell containing a positive electrode according to various embodiments and a control cell with a conventional PVDF positive electrode. (Example) Figure 23 As shown, using a positive electrode with a three-dimensional nano-carbon matrix (e.g., NX NMC811) can reduce the resistance by at least 20%.

[0249] Figure 24 A performance comparison chart is shown, illustrating the interaction between a battery cell containing a positive electrode according to various embodiments and a control cell with a conventional PVDF positive electrode. (Example) Figure 24As shown, using a positive electrode with a three-dimensional nano-carbon matrix (e.g., NX NMC811) can reduce the resistance by at least 20%.

[0250] Figure 25 A performance comparison graph is shown, showing a battery cell containing a positive electrode according to various embodiments and a control battery cell with a conventional PVDF positive electrode. Figure 25 The battery cell compared in this study includes an NX Si-C negative electrode (e.g., an electrode with a three-dimensional nano-carbon matrix), is a 1.5Ah cell, and was tested under 1C / 1C cycling conditions within a voltage range of 4.2–2.8V. Figure 25 As shown, the cathode using a three-dimensional carbon nanofiber matrix (e.g., NX NMC811) exhibits a higher discharge capacity density, and the difference in discharge capacity density increases with increasing cycle number. After 250 cycles, the discharge capacity of the cell according to various embodiments (e.g., a cell having a cathode comprising a three-dimensional carbon nanofiber matrix) is at least 1275 mAh, preferably at least 1375 mAh. After 250 cycles, the discharge capacity of the cell according to various embodiments (e.g., a cell having a cathode comprising a three-dimensional carbon nanofiber matrix) exceeds that of the control cell (e.g., a cell having a cathode comprising a PVDF matrix) by approximately 10%.

[0251] Figure 26 Performance diagrams of a battery cell comprising electrodes according to various embodiments are shown. Figure 26 The battery cell measured includes an NX Si-C negative electrode (e.g., an electrode with a three-dimensional nano-carbon matrix) and a positive electrode (e.g., a positive electrode with a three-dimensional nano-carbon matrix) according to various embodiments, and is a 1.5Ah battery cell, tested under 1C / 1C cycles within a voltage range of 4.2-2.8V. Figure 26 As shown, the cell containing a three-dimensional carbon nanofiber substrate cathode (e.g., NX NMC811) retains approximately 82.7% of its discharge capacity after 500 cycles. The discharge capacity of the cell containing a three-dimensional carbon nanofiber substrate cathode (e.g., NX NMC811) decreases by less than 300 mAh after 500 cycles.

[0252] Figure 27 Performance diagrams of a battery cell comprising electrodes according to various embodiments are shown. Figure 27 A fast charging cycle performance graph is provided. Figure 27 The battery cell measured includes an NX Si-C negative electrode (e.g., an electrode with a three-dimensional nano-carbon matrix) and a positive electrode according to various embodiments (e.g., a positive electrode with a three-dimensional nano-carbon matrix), and is a 1.5Ah battery cell (e.g., a pouch cell). Test conditions are performed at 4.2-2.8V voltage range, with 1C / 1C (3 cycles) + 3.5C (CCCV 15 minutes) / 1C (1 cycle) every 4 cycles. Figure 27 As shown, a battery cell containing a three-dimensional carbon nanofiber substrate cathode (e.g., NX NMC811) retains at least 87% of its discharge capacity after 500 cycles. In some embodiments, the battery cell containing a three-dimensional carbon nanofiber substrate cathode (e.g., NX NMC811) retains 87%-88% of its discharge capacity after 500 cycles. The discharge capacity of a battery cell containing a three-dimensional carbon nanofiber substrate cathode (e.g., NX NMC811) decreases by less than 300 mAh after 270 cycles.

[0253] Figure 28 Performance diagrams of a battery cell comprising electrodes according to various embodiments are shown. Figure 28 A graph showing the change in discharge energy over time is provided. Figure 28 The battery cell measured in the study includes an NX Si-C negative electrode (e.g., an electrode with a three-dimensional carbon nanofiber matrix) and a positive electrode according to various embodiments (e.g., a positive electrode with a three-dimensional carbon nanofiber matrix), with the positive electrode having a capacity of 5.6 mAh / cm³. 2 The electrode density was 3.5 g / cc, and the test conditions were 1C / 1C cycling within a voltage range of 4.2-3.0V. For example... Figure 28 As shown, a battery cell comprising a three-dimensional carbon nanofiber substrate cathode (e.g., NX NMC811) retains at least 70% of its discharge capacity after 600 cycles, preferably at least 80%. In some embodiments, the battery cell comprising a three-dimensional carbon nanofiber substrate cathode (e.g., NX NMC811) retains approximately 70% of its discharge capacity after 1000 cycles. In some embodiments, the battery cell comprising a three-dimensional carbon nanofiber substrate cathode (e.g., NX NMC811) retains between 80% and 90% of its discharge capacity after 600 cycles.

[0254] Figure 29 Performance diagrams of a battery cell comprising electrodes according to various embodiments are shown. Figure 29 A graph showing how capacity changes over storage time is provided. For example, the cell was tested for calendar life at 50 degrees Celsius and 100% state of charge (SOC100). Figure 29 The battery cell measured was a 1.5Ah pouch cell, comprising an NX Si-C negative electrode (e.g., an electrode having a three-dimensional carbon nanofiber matrix) and a positive electrode (e.g., a positive electrode having a three-dimensional carbon nanofiber matrix) according to various embodiments. Figure 29As shown, a cell containing a three-dimensional carbon nanofiber substrate cathode (e.g., NX NMC811) exhibits a capacity retention of at least 95% after 21 days. In some embodiments, the cell containing a three-dimensional carbon nanofiber substrate cathode (e.g., NX NMC811) exhibits a capacity retention of at least approximately 95% after 28 days. In some embodiments, the cell containing a three-dimensional carbon nanofiber substrate cathode (e.g., NX NMC811) exhibits a capacity retention of at least approximately 96% after 28 days. In some embodiments, the cell containing a three-dimensional carbon nanofiber substrate cathode (e.g., NX NMC811) exhibits a capacity retention of at least 1% higher than a control 1.5Ah pouch cell with a PVDF cathode after 28 days.

[0255] Figure 30 and Figure 31 The performance of a cell incorporating electrodes according to various embodiments of this application is demonstrated. Figure 30 and Figure 31 The cell for which performance data is provided is a pouch cell with dimensions of 46.5 mm x 46.5 mm x 7.14 mm, and the positive electrode contains a three-dimensional nano-carbon matrix (e.g., NX NMC811). Figure 30 A chart is provided that indicates the cell capacity design, specific energy, and energy density. Figure 31 A graph of cell voltage versus capacity is provided.

[0256] Figure 32 The weight distribution of the battery cells according to various implementation methods is shown. Figure 32 The cell whose weight distribution was measured was a 3.4Ah pouch cell with a positive electrode containing a three-dimensional nano-carbon matrix (e.g., NX NMC811).

[0257] Figure 33 and Figure 34 The performance of a cell incorporating electrodes according to various embodiments of this application is demonstrated. Figure 33 and Figure 34 The cell for which performance data is provided is a pouch cell with dimensions of 62 mm x 107 mm and 5.4 mm, and the positive electrode contains a three-dimensional nano-carbon matrix (e.g., NX NMC811). Figure 33 A chart is provided that indicates the cell capacity design, specific energy, and energy density. Figure 34A graph showing capacity versus DST (Dynamic Stress Testing) cycle count is provided. According to various embodiments, the cell has a specific energy greater than or equal to 315 Wh / kg, an energy density greater than or equal to 820 Wh / L, and a cell capacity of 9 Ah. The cell, according to various embodiments, exhibits DST cycle stability of at least approximately 70% at 1000 cycles, at least 92.5% at 225 cycles, and / or greater than 90% at 300 cycles.

[0258] Figure 35 and Figure 36 Performance graphs of a battery cell incorporating electrodes from various embodiments of this application are shown. For example... Figure 36 As shown, according to various embodiments, the cell (e.g., a 9Ah pouch cell comprising a three-dimensional nano-carbon matrix cathode) exhibits a volume expansion rate of less than 10% during charging from 0% to 100%. In some embodiments, such a cell exhibits a volume expansion rate of less than 9% during charging from 0% to 100%. In some embodiments, such a cell exhibits a volume expansion rate of approximately 8.8% during charging from 0% to 100%. Example

[0259] This embodiment demonstrates the use of graphite / SiO₂ in a battery cell without a fluorinated binder. x The cell performance is assessed when the negative electrode contains lithium iron manganese phosphate (LMFP) active material and the positive electrode contains lithium iron manganese phosphate (LMFP) active material. The binders used in both the positive and negative electrodes are relatively fluorine-free, with a fluorine content below 900 ppm. Based on the total weight of the cell, the amount of fluorine used in the cell is less than 900 ppm. The polymer binders used are free of perfluorinated and polyfluoroalkyl substances (PFASs).

[0260] The cathode active material (CAM) is a mixture of NCM811 and LMFP, and its content in the cathode layer is greater than 95 wt% based on the total weight of the cathode active layer. In all the figures below, the content of the cathode active material is greater than 95 wt% based on the total weight of the cathode active layer.

[0261] Figure 37 This demonstrates the specific energy variation with the SiO content in the negative electrode active layer. x A graph showing the change in SiO₂ content. During specific energy measurement, the battery's discharge capacity per unit area ranged from 3.5 to 5.0 mAh / cm². The graph shows that, relative to graphite in the negative electrode active layer, the higher the voltage, the higher the SiO₂ content. x The higher the content, the higher the specific energy. This cell exhibits a high energy density exceeding 275 Wh / kg and even exceeding 280 Wh / kg. With an initial capacity retention of 80%, the cell demonstrates a long cycle life of over 1000 cycles.

[0262] Figure 38 The graph shows the specific energy as a function of the LMFP content in the positive electrode. As mentioned above, the positive electrode active layer contains a mixture of NCM811 and LMFP. The negative electrode contains SiO2. x The content relative to graphite is 10 wt%. From Figure 38 As can be seen, the battery's discharge capacity per unit area ranges from 3.5 to 6.0 mAh / cm² during specific energy measurement. The figure shows that, relative to the NMC in the positive electrode active layer, higher voltage and lower LMFP content result in higher specific energy. This cell exhibits high energy densities exceeding 305 Wh / kg and even exceeding 320 Wh / kg. With an initial capacity retention of 80%, the cell demonstrates a long cycle life exceeding 1000 cycles.

[0263] Figure 39 The graph shows the specific energy as a function of the LMFP content in the positive electrode. As mentioned above, the positive electrode active layer contains a mixture of NCM811 and LMFP. The negative electrode contains SiO2. x The graphite content is 30 wt%. Figure 39 As can be seen, the battery's discharge capacity per unit area ranges from 3.0 to 6.0 mAh / cm² during specific energy measurement. The figure shows that, relative to the NMC in the positive electrode active layer, higher voltage and lower LMFP content result in higher specific energy. This cell exhibits high energy densities exceeding 330 Wh / kg and even exceeding 360 Wh / kg. With an initial capacity retention of 80%, the cell demonstrates a long cycle life exceeding 1000 cycles.

[0264] Figure 40 The graph shows the specific energy as a function of the LMFP content in the positive electrode. As mentioned above, the positive electrode active layer contains a mixture of NCM811 and LMFP. The negative electrode contains SiO2. x The graphite content is 40 wt%. Figure 40 As can be seen, the battery's discharge capacity per unit area ranges from 3.0 to 6.0 mAh / cm² during specific energy measurement. The figure shows that, relative to the NMC in the positive electrode active layer, higher voltage and lower LMFP content result in higher specific energy. This cell exhibits a high energy density exceeding 360 Wh / kg, and even exceeding 370 Wh / kg. With an initial capacity retention of 80%, the cell demonstrates a long cycle life exceeding 1000 cycles.

[0265] Figure 41 This demonstrates the specific energy variation with the SiO content in the negative electrode active layer. xA graph showing the change in SiO₂ content. During specific energy measurement, the battery's discharge capacity per unit area ranged from 4.0 to 6.0 mAh / cm². The graph shows that, relative to graphite in the negative electrode active layer, the higher the voltage, the higher the SiO₂ content. x The higher the content, the higher the specific energy. This cell exhibits a high energy density exceeding 350 Wh / kg, and even exceeding 360 Wh / kg. With an initial capacity retention of 80%, the cell demonstrates a long cycle life of over 1000 cycles.

[0266] from Figures 37 to 41 It can be seen that when SiO x When the content (based on the total weight of the negative electrode active material) is greater than 50 wt%, preferably greater than 70 wt%, and more preferably greater than 80 wt%, the performance of the energy storage cell is improved. As mentioned above, the negative electrode active material contains SiO x (where x is 1 to 4) and graphite.

[0267] At the same time, from Figures 37 to 41 It can be seen that when the content of LMFP (based on the total weight of the positive electrode active material) is less than 50 wt%, preferably less than 30 wt%, and more preferably less than 20 wt% (the remainder being NCM), the performance of the energy storage cell is improved.

[0268] Various other components can be provided and utilized to implement the various aspects of the teachings herein. For example, additional materials, combinations of materials, and / or the omission of certain materials can be used to provide more implementations within the scope of the teachings herein. Many modifications can be made to the teachings herein. Typically, designs can be tailored to the needs of users, designers, manufacturers, or other similarly interested parties. The purpose of modifications may be to meet specific performance criteria deemed important by that party.

[0269] Unless the terms "means for..." or "steps for..." are used explicitly in a particular claim, the appended claims or elements thereof should not be construed as invoking the provisions of 35 USC §112(f).

[0270] When introducing elements of this application or its embodiments, the articles "an," "a," and "described" are intended to indicate the presence of one or more of that element. Similarly, the adjective "another," when used to introduce an element, is intended to indicate one or more elements. The terms "comprising" and "having" are intended to be inclusive, meaning that other elements may be present in addition to those listed. As used herein, the term "exemplary" is not intended to imply a best or most prominent example. Rather, "exemplary" refers to an example of an embodiment as one of many possible implementations.

[0271] The following examples are for illustrative purposes only and are not intended to limit the scope of this application. Unless otherwise stated, all examples are based on simulations.

[0272] In general, this application may alternatively consist of, or substantially consist of, any suitable components disclosed herein.

Claims

1. An energy storage device, comprising: an electrolyte; an active layer, comprising: a negative active material comprising silicon and graphite: a positive active layer, comprising: a positive active material comprising a mixture of LMFP and NCM; wherein the content of NCM is higher than LMFP; wherein each of the negative active material and the positive active material comprises a polymer binder having a fluorine content lower than 900 ppm.

2. The energy storage device of claim 1, wherein the silicon comprises SiO x particles in the form of SiOx, where x is 1 to 4.

3. The energy storage device of claim 1, wherein the silicon is micro-silicon.

4. The energy storage device of claim 2, wherein, The content of SiO x is greater than 50 wt% based on the total weight of the negative active material.

5. The energy storage device of claim 1, wherein, The content of SiO x is greater than 80 wt% based on the total weight of the negative active material.

6. The energy storage device of claim 1, wherein, the content of the LMFP is less than 50 wt% based on the total weight of the positive active material.

7. The energy storage device of claim 1, wherein, the content of the negative active material in the negative active layer is greater than or equal to 90 wt% based on the total weight of the negative active layer.

8. The energy storage device of claim 1, wherein, the content of the negative active material in the negative active layer is greater than or equal to 95 wt% based on the total weight of the negative active layer.

9. The energy storage device of claim 1, wherein, the content of the positive active material in the positive active layer is greater than or equal to 90 wt% based on the total weight of the negative active layer.

10. The energy storage device of claim 1, wherein, the content of the positive active material in the positive active layer is greater than or equal to 95 wt% based on the total weight of the negative active layer.

11. The energy storage device of claim 1, wherein the negative active layer further comprises a conductive additive.

12. The energy storage device of claim 1, wherein the positive active layer further comprises a conductive additive.

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