Electrodes for energy storage devices comprising copolymerized binders

Abstract

An electrode useful in an energy storage device, the electrode comprising a current collector and an active layer on the current collector wherein the active layer comprises electrode active particles, a conductive material and a binder wherein the binder comprises a copolymer comprising a first repeating unit and a second repeating unit; wherein the first repeating unit is derived from polymerization of a first monomer, the first monomer being an ethylenically unsaturated monomer having a hydrophilic pendant group, and the second repeating unit is derived from polymerization of a second monomer having an ethylenically unsaturated property.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of U.S. Patent Application No. 63 / 417,124, filed on October 18, 2022, which is hereby incorporated by reference in its entirety. Technical Field

[0003] The present invention relates to an energy storage device, particularly supercapacitors and lithium - ion batteries, and electrodes used therein. Background Art

[0004] Lithium batteries are used in many products, including medical devices, electric vehicles, aircraft, and consumer products (such as laptop computers, mobile phones, and cameras). Due to the high energy density, high operating voltage, and low self - discharge of lithium - ion batteries, they have replaced the secondary battery market and continue to find new uses in products and emerging industries.

[0005] Generally, a lithium - ion battery (“LIB” or “LiB”) includes an anode, a cathode, and an electrolyte material, such as an organic solvent containing a lithium salt. More specifically, a paste or slurry is formed by mixing an anode active material or a cathode active material with a binder and a solvent, and then the paste or slurry is coated on a current collector (such as aluminum or copper) and dried to form a film on the current collector, thereby forming the anode and the cathode (collectively referred to as “electrodes”). Then the anode and the cathode are layered or wound, and then placed in a pressurized housing containing the electrolyte material, and together they form a lithium - ion battery.

[0006] Binders are used to adhere the active material in a suitable coating to the current collector. Importantly, the binder helps to maintain sufficient contact between the active material and the current collector. In addition, it is important to select a binder that is mechanically compatible with the electrode active material so that it can withstand the degree of expansion and contraction of the electrode active material during charging and discharging of the battery. The binder must also be sufficient to withstand the manipulation of the electrode when assembling the electrode into the battery housing.

[0007] Therefore, binders such as cellulose binders or cross - linked polymer binders have been used to provide good mechanical properties. However, in conventional electrodes, the selected binder typically requires environmentally unfriendly or toxic solvents for processing. Summary of the Invention

[0008] The present disclosure relates to an electrode comprising a current collector and an active layer on the current collector, wherein the active layer comprises electrode active particles, a conductive material, and a binder, wherein the binder comprises a copolymer, the copolymer comprising a first repeating unit and a second repeating unit; wherein the first repeating unit is derived from the polymerization of a first monomer, the first monomer being an ethylenically unsaturated monomer having a hydrophilic side group, and the second repeating unit is derived from the polymerization of a second monomer having ethylenic unsaturation.

[0009] The present disclosure also relates to an energy storage device comprising such an electrode.

[0010] The present disclosure also relates to a method of making such an electrode, the method comprising providing a slurry comprising a conductive element, a binder, and an electrode active material, the slurry in water, an alcohol, or a combination thereof, applying the slurry to a current collector, and drying to remove the solvent. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The following is a brief description of the drawings, in which like elements are numbered alike and are presented for the purpose of illustrating the exemplary embodiments disclosed herein and not for the purpose of limiting the exemplary embodiments.

[0012] Figure 1 is a diagram of an example of an electrode as disclosed herein;

[0013] Figure 2 is a flowchart showing an example of a method that can be used to make an electrode as disclosed herein;

[0014] Figure 3 is a depiction of an electrode arrangement of a pouch cell device; and

[0015] Figure 4 is a depiction of a schematic cross-sectional view showing aspects of an energy storage device (ESD). DETAILED DESCRIPTION

[0016] A more complete understanding of the components, processes, and devices disclosed herein can be obtained by reference to the drawings. These drawings are merely schematic representations for convenience and ease of demonstrating the present disclosure and are, therefore, not intended to indicate the relative size and dimensions of the device or its components and / or to define or limit the scope of the exemplary embodiments. Although specific terms are used in the following description for clarity, these terms are intended to refer only to the particular structure of the embodiments selected for illustration in the drawings and are not intended to limit or define the scope of the present disclosure. In the drawings and the following description, it should be understood that like reference numerals denote like components.

[0017] Disclosed herein is an electrolyte cell including a housing that includes electrodes (an anode and a cathode). The housing includes an electrolyte that contacts the anode and the cathode. Both electrodes (the anode and the cathode) include current collectors having an active layer disposed thereon. The active layer may be disposed on an optional adhesion layer that contacts the electrode.

[0018] Figure 1 FIG. is an example of an electrode (anode and cathode) as disclosed herein. In the example shown, electrode 100 includes a current collector 102 and an active layer 106. Electrode 100 may optionally include an adhesion layer 104. As an example, adhesion layer 104 includes a material that promotes adhesion between current collector 102 and active layer 106. Active layer 106 includes an electrode active material 110 and a conductive element 108 in a binder. The conductive element may include a high aspect ratio element.

[0019] Current collector 102 is a conductive element. The current collector may include a metal (e.g., a substantially pure metal or a metal alloy, etc.). As another example, current collector 102 may be in the form of a metal strip or a metal foil. For example, current collector 102 may be an aluminum foil or an aluminum strip, an aluminum alloy foil or an aluminum alloy strip, a copper foil or a copper strip, or a copper alloy foil or a copper alloy strip. Current collector 102 may have a thickness of no more than 15 μm (micrometers), no more than 10 μm, no more than 8 μm, or no more than 5 μm. In some embodiments, while the current collector may have a thickness of at least 3 μm. For example, current collector 102 may have a thickness of 3 μm to 15 μm or 6 μm to about 8 μm. As another example, current collector 102 is an aluminum foil or an aluminum alloy foil having a thickness of 5 μm to 7 μm.

[0020] Active layer 106 includes a conductive material, a binder material, and an electrode active material. The active layer may be manufactured by mixing a conductive material, a binder material, and an electrode active material with a solvent to form a mixture. The mixture may be applied directly to the current collector or to an adhesion layer that can adhere to the current collector. If an adhesion layer is used, it may be conductive. The mixture may be dried to remove the solvent, leaving a solid active layer.

[0021] Conductive element

[0022] The conductive element (also referred to as the conductive material) may include carbon. For example, the conductive element may be a high aspect ratio carbon element. The term "high aspect ratio carbon element" refers to a carbon-containing element having dimensions in one or more dimensions ("major dimensions") that are significantly greater than the dimensions of the element in the transverse dimension ("minor dimensions"). The high aspect ratio carbon element may include a substantially cylindrical network of carbon atoms. The conductive material may include carbon nanotubes or a plurality of first carbon nanotube bundles.

[0023] The conductive material can form a conductive percolation network that can conduct current between any two separate points on the surface of a solid active layer (where there is no solvent). In other words, by means of physical contact or electron hopping between conductive elements in the electrode active layer, current can be transmitted from one surface or end of the active layer to the opposite surface or end. The percolation network can include voids between high aspect ratio carbon elements that can contain or accommodate the electrode active material. The high aspect ratio conductive material can be oriented substantially in the direction parallel to the current collector in the electrode active layer 106 to facilitate conduction of current from one end of the electrode to the other end, while also maintaining some minor orientation through the thickness of the active layer.

[0024] Based on the total weight of the mixture (the mixture contains the conductive material, the electrode active material, the binder material, and the solvent), the conductive material can be present in the mixture in an amount of 0.1 wt% to 1.3 wt%, or 0.15 wt% to 1.2 wt%, or 0.3 wt% to 1 wt%. Based on the total weight of the solids in the active layer (the total weight of the solids contains the conductive material, the binder material, the electrode active material, and does not contain the solvent), the conductive material can be present in the active layer in an amount of 0.2 wt% to 3.5 wt%, or 0.3 wt% to 3 wt%, or 0.5 wt% to 2 wt%.

[0025] The high aspect ratio carbon elements can be single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWNTs), or a mixture of both.

[0026] The single-walled carbon nanotubes can have an outer diameter of 0.5 nanometers to 5.0 nanometers, preferably 1.0 nanometers to 3.5 nanometers. The single-walled carbon nanotubes can have an aspect ratio (length to diameter ratio) greater than about 2.0, preferably greater than 5.0, preferably greater than 10.0, greater than 50, and even more preferably greater than 100. In one exemplary embodiment, the single-walled carbon nanotubes can have an average aspect ratio of 5 to 200.

[0027] The single-walled carbon nanotubes can have a length greater than 6 nanometers, preferably greater than 10 nanometers, preferably greater than 15 nanometers, preferably greater than 30 nanometers, preferably greater than 50 nanometers, more preferably greater than 100 nanometers, preferably greater than 1 micrometer, preferably greater than 5 micrometers, preferably greater than 10 micrometers, and even more preferably greater than 15 micrometers up to at least 200 micrometers. In one exemplary embodiment, the single-walled carbon nanotubes can have an average length of 10 nanometers to 20 micrometers, preferably 20 nanometers to 15 micrometers.

[0028] Based on the total weight of the mixture, single-walled carbon nanotubes can be present in the mixture of the conductive material, the binder material, the electrode active material, and the solvent in an amount of 0.1 wt% to 2 wt%. For example, the amount of single-walled carbon nanotubes in the mixture can be 0.1 wt% to 0.3 wt% or 0.15 wt% to 9.25 wt%. As another example, the amount of single-walled carbon nanotubes in the mixture can be 0.4 wt% to 2 wt%.

[0029] Based on the total weight of the electrode active layer, single-walled carbon nanotubes can be present in the electrode active layer (the conductive material, the binder material, and the electrode active material, excluding the solvent) in an amount of 0.2 wt% to 4 wt% (wt%). For example, the amount of single-walled carbon nanotubes in the electrode active layer can be 0.2 wt% to 0.6 wt% or 0.3 wt% to 0.5 wt%. As another example, the amount of single-walled carbon nanotubes in the electrode active layer can be 0.5 wt% to 4 wt%.

[0030] The number of carbon walls in the multi-walled carbon nanotubes can be 2 or more, 5 or more, 10 or more, 50 or more. The multi-walled carbon nanotubes can include an average of 3 to 15 layers, 4 to 12 layers, 5 to 10 layers, 6 to 8 layers.

[0031] The active layer 106 can include multi-walled carbon nanotubes and single-walled carbon nanotubes. When the multi-walled carbon nanotubes and the single-walled carbon nanotubes are wetted by the electrolyte in the energy storage device having the electrode 100, the multi-walled carbon nanotubes swell more than the single-walled carbon nanotubes. For example, when the multi-walled carbon nanotubes and the single-walled carbon nanotubes are wetted by the electrolyte in the energy storage device in which the electrode 100 is located, the multi-walled carbon nanotubes can swell at least 15%, or at least 25%, or at least 50% more than the single-walled carbon nanotubes. For example, when the multi-walled carbon nanotubes and the single-walled carbon nanotubes are wetted by the electrolyte, the length of the multi-walled carbon nanotubes swells at least 15%, or at least 25%, or at least 50% more than the length of the single-walled carbon nanotubes. As another example, the multi-walled carbon nanotubes swell up to 50% when wetted (for example, the length of the multi-walled carbon nanotubes is 50% greater after being wetted by the electrolyte, and / or the diameter of the multi-walled carbon nanotubes is 50% greater after wetting, etc.).

[0032] Multi-walled carbon nanotubes can have an outer diameter of from 2.0 nanometers to 50 nanometers, from 5.0 nanometers to 40 nanometers, or from 6 nanometers to 10 nanometers. Multi-walled carbon nanotubes can have a length greater than 10 nanometers, greater than 15 nanometers, greater than 30 nanometers, greater than 50 nanometers, greater than 100 nanometers, greater than 500 nanometers, greater than 1 micrometer, greater than 5 micrometers, greater than 10 micrometers or greater than 15 micrometers. At the same time, multi-walled carbon nanotubes can have an average length of up to 25 micrometers or up to 20 micrometers. In an exemplary embodiment, the multi-walled carbon nanotubes have an average length of from 10 nanometers to 20 micrometers or from 20 nanometers to 15 micrometers. Multi-walled carbon nanotubes can have an aspect ratio (length to diameter ratio) greater than 5.0, greater than 10.0, greater than 50, greater than 100 or greater than 500.

[0033] The electrode includes multi-walled carbon nanotubes that can be relatively long compared to the multi-walled carbon nanotubes included in related art electrodes. The use of relatively long multi-walled carbon nanotubes in the electrode has been found to have beneficial mechanical and / or electrical properties. For example, multi-walled carbon nanotubes provide relatively good power at low density. As another example, shorter multi-walled carbon nanotubes generally do not swell (e.g., expand) as much as longer multi-walled carbon nanotubes. Thus, the use of shorter multi-walled carbon nanotubes loses (or reduces) some of the beneficial properties associated with carbon nanotube swelling. As an extreme example, carbon black does not exhibit swelling because carbon black is merely particles of carbon without entanglement, such as the entanglement exhibited by a set of multi-walled carbon nanotubes. An indication that a quantity of multi-walled carbon nanotubes has a length exceeding a threshold length and thus has sufficient swelling properties is the observation during the calendering process - calendering with a relatively large amount of pressure or effort applied to the slurry related to the foil indicates that the total swelling (e.g., average swelling) of the multi-walled carbon nanotubes in the active layer will meet a specific property threshold. However, multi-walled carbon nanotubes are generally difficult to process.

[0034] The processing of multi-walled carbon nanotubes related to the preparation / formation of the active layer and / or the electrode is milder than the processes for electrodes in the related art. Accordingly, longer multi-walled carbon nanotubes are maintained according to the processes in various embodiments (e.g., fewer multi-walled carbon nanotubes are crushed, broken, fractured, etc.). In some embodiments, the active layer of the electrode comprises a set of multi-walled carbon nanotubes having an average length greater than the average length of the multi-walled carbon nanotubes in electrodes of the related art. According to various embodiments, the length distribution of the set of multi-walled carbon nanotubes is skewed towards multi-walled carbon nanotubes of a nominal length. As an example, the nominal length of the multi-walled carbon nanotubes is about 16 microns. For example, the multi-walled carbon nanotubes are processed and / or applied in a manner that reduces or minimizes breakage or fracture of the multi-walled carbon nanotubes. The length of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements is typically the nominal length of the multi-walled carbon nanotubes, or the length of such multi-walled carbon nanotubes tends to be more severely skewed towards the nominal length. In some embodiments, at least 75% of the multi-walled carbon nanotubes within the network of high aspect ratio carbon elements are within 10% of the nominal length (e.g., between 13.4 microns and about 15 microns). In some embodiments, at least 75% of the multi-walled carbon nanotubes within the network of high aspect ratio carbon elements have a length of at least 12 microns. In some embodiments, at least 75% of the multi-walled carbon nanotubes within the network of high aspect ratio carbon elements have a length of at least 13 microns. In some embodiments, at least 50% of the multi-walled carbon nanotubes within the network of high aspect ratio carbon elements are within 10% of the nominal length (e.g., between 13.4 microns and about 15 microns). In some embodiments, at least 50% of the multi-walled carbon nanotubes within the network of high aspect ratio carbon elements have a length of at least 12 microns. In some embodiments, at least 50% of the multi-walled carbon nanotubes within the network of high aspect ratio carbon elements have a length of at least 8 microns. In some embodiments, at least 50% of the multi-walled carbon nanotubes within the network of high aspect ratio carbon elements have a length of at least 13 microns.

[0035] According to various embodiments, the length distribution of the set of multi-walled carbon nanotubes is skewed towards multi-walled carbon nanotubes of a nominal length. For example, the multi-walled carbon nanotubes are processed and / or applied in a manner that reduces or minimizes breakage or fracture of the multi-walled carbon nanotubes. The length of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements is typically the nominal length of the multi-walled carbon nanotubes, or the length of such multi-walled carbon nanotubes tends to be more severely skewed towards the nominal length.

[0036] In some embodiments, at least 75% of the multi-walled carbon nanotubes within the network of high aspect ratio carbon elements are within 10% of the nominal length (e.g., between 13.4 microns and about 15 microns). In some embodiments, at least 75% of the multi-walled carbon nanotubes within the network of high aspect ratio carbon elements have a length of at least 12 microns. In some embodiments, at least 75% of the multi-walled carbon nanotubes within the network of high aspect ratio carbon elements have a length of at least 13 microns. In some embodiments, at least 50% of the multi-walled carbon nanotubes within the network of high aspect ratio carbon elements are within 10% of the nominal length (e.g., between 13.4 microns and about 15 microns). In some embodiments, at least 50% of the multi-walled carbon nanotubes within the network of high aspect ratio carbon elements have a length of at least 12 microns. In some embodiments, at least 50% of the multi-walled carbon nanotubes within the network of high aspect ratio carbon elements have a length of at least 13 microns.

[0037] Based on the total weight of the mixture, the multi-walled carbon nanotubes may be present in the mixture (the mixture comprising a conductive material, an electrode active material, a binder material, and a solvent) in an amount of 0.3 wt% to 1.0 wt%, preferably 0.4 wt% to 0.9 wt%. Based on the total weight of the solid anode active material, the multi-walled carbon nanotubes are present in the solid anode active layer (the solid active layer comprising a conductive material, a binder material, an electrode active material, and no solvent) in an amount of 0.8 wt% to 2.6 wt%, preferably 1.0 wt% to 1.8 wt%.

[0038] In an example where both multi-walled carbon nanotubes and single-walled carbon nanotubes are used, the ratio of the weight of the multi-walled carbon nanotubes to the weight of the single-walled carbon nanotubes in the mixture or in the solid active material layer may be at least 2:1.

[0039] In one example, the three-dimensional network of the high aspect ratio carbon element 108 comprises carbon nanotubes, and the carbon nanotubes are only multi-walled carbon nanotubes and / or fragments of such carbon nanotubes.

[0040] In another example, based on the weight of the conductive material, the multi-walled carbon nanotubes are present in the mixture or in the solid anode active material layer in an amount of at least twice the amount of the single-walled carbon nanotubes.

[0041] The network of the three-dimensional network of the high aspect ratio carbon element 108 may comprise at least 99 wt% carbon.

[0042] The three-dimensional network of the high aspect ratio carbon element 108 may include an electrical interconnect network of carbon elements presenting connectivity above the percolation threshold, and wherein the network defines one or more highly conductive pathways having a length greater than 100 μm. The percolation threshold is the threshold at which conductive elements contact each other to provide a conductive network measured between any two points on any surface across the network.

[0043] Electrode active material

[0044] The active material will typically be different for the anode and for the cathode.

[0045] For example, the anode active material can include silicon (Si), germanium (Ge), tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), titanium (Ti), nickel (Ni), cobalt (Co), cadmium (Cd); alloys of two or more of them or alloys of them with other elements; oxides, carbides, nitrides, sulfides, phosphides, selenides, and tellurides of these metals and their mixtures or lithium-containing composites; salts and hydroxides of Sn; lithium titanate, lithium manganate, lithium aluminate, lithium-containing titanium oxides, lithium transition metal oxides; their prelithiated forms; Li, Li alloys or particles of surface-stabilized Li having at least 60 wt% lithium; or combinations thereof. The active material can include graphite instead of or in addition to the anode active material. As an example, the anode active material can include silicon oxide and / or carbon silicon oxide. Such anode active material containing silicon oxide or carbon silicon oxide can further include graphite.

[0046] For example, the cathode active material can include lithium cobalt oxide (LCO, sometimes referred to as "lithium cobaltate" or "lithium cobalite"). Examples of LCO formulations include LiCoO2; lithium nickel manganese cobalt oxide (NMC, having the variant formula LiNiMnCO); lithium manganese oxide (LMO having variant formulas such as LiMn2O4, Li2MnO3, etc. or combinations thereof); lithium titanium oxide (LTO, where one variant formula is Li4Ti5O 12 ); lithium iron phosphate oxide (LFP, where one variant formula is LiFePO4), lithium nickel cobalt aluminum oxide (and its variants as NCA), and other similar materials. Other variants of the foregoing can be included.

[0047] In the case where NMC is used as the active material, nickel-rich NMC can be used. For example, a variant of NMC can be LiNi x Mn y Co (1-x-y) , where x is equal to or greater than about 0.7, 0.75, 0.80, 0.85 or greater, y is equal to or greater than 0.1, 0.15, 0.2 or 0.25, and x + y is less than 1. For example, NMC811 can be used, where x is about 0.8 and y is about 0.1. Alternatively, the active material can include an oxide of lithium nickel manganese cobalt (LiNi x Mn y Co zO2). Variants of this formula that can be used in the active material layer include NMC 111 (detailed below), NMC532 (LiNi 0.5 Mn 0.3 Co 0.2 O2), NMC622 (LiNi 0.6 Mn 0.2 Co 0.2 O2), or combinations thereof.

[0048] In one embodiment, the active material used in both electrodes (anode and / or cathode) can also comprise a nickel-rich combination of nickel, manganese, and cobalt. Lithium-nickel-manganese-cobalt-oxide (LiNiMnCoO2), abbreviated as NMC, provides strong overall performance, excellent specific energy, and the lowest self-heating rate among all mainstream cathode powders. Based on the total weight of the NMC blend, the NMC powder can contain nickel in an amount of 20 wt% to 40 wt%, manganese in an amount of 20 wt% to 40 wt%, and cobalt in an amount of 20 wt% to 40 wt%. While the term "NMC powder" can refer to a variety of blends, it is desirable to use a blend comprising 33 wt% nickel, 33 wt% manganese, and 33 wt% cobalt. This blend (sometimes referred to as 1-1-1 (NMC 111)) is useful for applications that use frequent cycling (automotive, energy storage) because of the reduced material cost achieved by the lower cobalt content (nickel-rich combination of nickel, manganese, and cobalt (NMC)). Based on the total weight of the NMC blend, the NMC powder can contain nickel in an amount of 20 wt% to 40 wt%, manganese in an amount of 20 wt% to 40 wt%, and cobalt in an amount of 20 wt% to 40 wt%. While the term "NMC powder" can refer to a variety of blends, it is desirable to use a blend comprising 33 wt% nickel, 33 wt% manganese, and 33 wt% cobalt. This blend (sometimes referred to as 1-1-1) is useful for applications that use frequent cycling (automotive, energy storage) because of the reduced material cost achieved by the lower cobalt content. Lithium-nickel-manganese-cobalt-oxide (LiNiMnCoO2) provides strong overall performance, excellent specific energy, and the lowest self-heating rate among all mainstream cathode powders.

[0049] As described above, the active material can be contained or accommodated within a network of high aspect ratio active material present in the electrode active layer. Based on the total weight of the electrode mixture (the mixture used to fabricate the electrode active layer, which contains an electrode polymer binder material, an electrode active material, a conductive material, and a solvent), the active material can be present in the mixture used to form the electrode in an amount of 35 wt% to 75 wt%, preferably 40 wt% to 70 wt%. Based on the total weight of the cathode active layer, the electrode active material is present in the electrode active layer (which does not contain solvent) in an amount of 95 wt% to 98.5 wt%.

[0050] Binder

[0051] The binders described herein can provide the ability to fabricate electrodes using water and / or alcohol as solvents. These binders can also provide good adhesion bonding, good dispersion of the slurry components (i.e., electrode active material, binder, and conductive material), and / or good stability during battery charging and discharging. The binders described herein comprise a copolymer, consist essentially of a copolymer, or consist of a copolymer. For example, the copolymer can be the polymerization reaction product of a first monomer and a second monomer. The first monomer can provide hydrophilic side groups on the copolymer binder, which at least contribute to handling in water and / or alcohol and good dispersion of the slurry components, while reducing the solubility of the binder in carbonate-based electrolytes. When used in an energy storage device (e.g., a battery, particularly a lithium-ion battery), the second monomer can provide enhanced mechanical properties and / or electrochemical and chemical stability. Thus, the polymerized first monomer can provide carboxylic acid groups, carboxylate groups, acetate groups, ester groups, nitrile groups, hydroxyl groups, or amide groups as hydrophilic side groups for the polymer, which can enhance solubility in water and / or alcohol. The second monomer can provide flexibility, thereby avoiding rigidity that may cause the binder material to break.

[0052] The copolymer comprises a first repeating unit A and a second repeating unit B having different and distinct formulas. Unit A can be represented by the following formula:

[0053]

[0054] wherein R is independently H, an alkyl group of 1 to 3 carbon atoms each time it appears, or one of the Rs can be the same as P defined below. R can be H. P represents a hydrophilic side group. P can be -LCOOR 1 , wherein R 1 is H, a monovalent metal ion (such as Na + , K + or Li + ), or a hydrocarbon group of 1 to 3 carbon atoms (preferably a divalent alkyl group), preferably R 1 is H or a monovalent metal ion; -LC(O)N(R 2 )2, wherein R 2 is independently H or an alkyl group of 1 to 3 carbon atoms, preferably 1 carbon atom, each time it appears; -OC(O)-R 3 , wherein R 3 is H or an alkyl group of 1 to 3, preferably 1 carbon atom; -LCN; or LOH; wherein each time it appears, L represents a direct bond or a divalent linking group, such as a hydrocarbon of 1 to 3 carbon atoms, preferably a divalent alkyl group of 1 to 3 carbon atoms, and L is preferably a direct bond. P is preferably -COOR1 。

[0055] Unit B can be represented by the following formula:

[0056]

[0057] wherein each occurrence of R' is independently H; a hydrocarbon having 1 to 3 carbon atoms (preferably a divalent alkyl group), such as methyl; a nitrile group, such as -CN; -LOH; -LCOOR 4 , wherein R 4 is a hydrocarbon group having 1 to 3 carbon atoms, wherein L represents a direct bond or a divalent linking group, such as a hydrocarbon having 1 to 3 carbon atoms, preferably a divalent alkyl group having 1 to 3 carbon atoms, L is preferably a direct bond; or a 4-, 5- or 6-membered lactam ring bonded to the main chain of the repeating unit through a nitrogen atom, preferably at least three of the R's are H. The remaining R' can be a hydrocarbon having 1 to 3 carbon atoms, such as methyl; -COOR 4 , wherein R 4 is a hydrocarbon group having 1 to 3 carbon atoms; or a 4-, 5- or 6-membered lactam ring bonded to the main chain of the repeating unit through a nitrogen atom. If R' is a lactam ring, it preferably has the following structure:

[0058]

[0059] The copolymer can comprise two or more different A repeating units, or two or more different B repeating units. The copolymer can be a random copolymer, a block copolymer or an alternating copolymer. For example, the copolymer can be a random copolymer of a single type of A repeating unit and a single type of B repeating unit, or can be a random copolymer of two different A repeating units and one or two types of B repeating units.

[0060] The copolymer can be prepared by known polymerization techniques for ethylenically unsaturated monomers (e.g., addition polymerization). The polymerization can be, for example, solution polymerization or emulsion polymerization.

[0061] Monomers useful for forming repeating unit A include ethylenically unsaturated carboxylic acid functional monomers, such as acrylic acid, methacrylic acid and salts of such acids; ethylenically unsaturated acetates, such as vinyl acetate; ethylenically unsaturated esters, such as vinyl esters, e.g., alkyl acrylates, such as methyl methacrylate; tert-butyl methacrylate, ethylenically unsaturated amides, such as acrylamide; ethylenically unsaturated diacids, such as itaconic acid; ethylenically unsaturated nitriles, such as acrylonitrile; ethylenically unsaturated alcohols, such as vinyl alcohol.

[0062] Monomers that can be used to form repeating unit B include ethylenically unsaturated acetates such as vinyl acetate, provided that it is not used as repeating unit A; ethylenically unsaturated esters such as vinyl esters, for example alkyl acrylates such as methyl methacrylate, provided that it is not used as repeating unit A; ethylene; propylene; butylene; and vinylpyrrolidone. Ethylene and vinylpyrrolidone are preferred.

[0063] Specific examples of such copolymers include acrylic acid / vinylpyrrolidone copolymers (e.g., available commercially as Ultrathix TM from Ashland Chemical), vinyl acetate / vinylpyrrolidone copolymers (e.g., available commercially from Shanghai Dexiang Medicine Tech), ethylene / acrylic acid copolymers (e.g., available commercially from Dow Chemical, DuPont, or BASF), vinyl acetate / vinylpyrrolidone / itaconic acid terpolymers (e.g., available commercially from Dayang Chem (Hangzhou) Co., Ltd), methacrylic acid / methyl methacrylate copolymers (available commercially from Alfa Chemistry), acrylic acid / acrylonitrile copolymers, and methyl methacrylate / N,N-dimethylacrylamide copolymers.

[0064] The molar ratio of repeating unit A to repeating unit B can be from 1:9 to 9:1, 2:8 to 8:2, 3:7 to 7:3, 4:6 to 6:4, or about 1:1.

[0065] The weight-average molecular weight of the polymer determined by gel permeation chromatography can be from 5,000 g / mol to 2,000,000 g / mol, or from 10,000 g / mol to 1,000,000 g / mol.

[0066] If desired, the polymer can contain crosslinking functional groups or a crosslinking agent can be added such that the adhesive polymer can be crosslinked before completion of the production of the electrode active layer.

[0067] The polymers described above can be used as the sole polymer in an adhesive. Alternatively, the polymers described above can be used in a blend with a different second polymer as described above. As another alternative, the polymers described above can be blended with one or more other known polymer adhesives. However, to take full advantage of the polymers described above, the additional polymers are preferably also soluble or dispersible in water, alcohol, or a combination thereof. When used in a blend, based on the total weight of the polymers in the blend, the polymers described above preferably make up at least 10 wt%, at least 20 wt%, at least 30 wt%, at least 40 wt%, at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, or at least 99 wt% of the blend.

[0068] Form an electrode

[0069] An electrode can be produced by first preparing a mixture (sometimes referred to as a slurry) of a conductive element, an active material, and an adhesive in a solvent. The advantage of the adhesives described herein is that water, alcohol, or a combination thereof can be used as the solvent to form a useful slurry. The slurry can then be directly coated onto a current collector or applied to a current collector having an intermediate adhesion layer.

[0070] The slurry can be prepared in a single step. Alternatively, the slurry can be prepared according to a multi-step method as shown in the flowchart of Figure 2 which depicts an example of method 600 provided for electrode 100 of Figure 1 At 610, a conductive material (e.g., a high aspect ratio carbon element) and a surface treatment material (e.g., a surfactant, an adhesive material as described herein, or both) are combined with a solvent (e.g., water, alcohol, or a combination thereof) to form an initial slurry.

[0071] At 620, the initial slurry is processed to ensure good dispersion of the solid materials in the slurry. This processing can include introducing mechanical energy into the mixture of the solvent and the solid materials (e.g., using an ultrasonic device, which is sometimes also referred to as an "ultrasonic") or other suitable mixing devices (e.g., a high shear mixer). For example, the mechanical energy introduced into the mixture can be at least 0.4 kilowatt-hours per kilogram (kWh / kg), 0.5 kWh / kg, 0.6 kWh / kg, 0.7 kWh / kg, 0.8 kWh / kg, 0.9 kWh / kg, 1.0 kWh / kg, or greater. For example, the mechanical energy introduced per kilogram of the mixture into the mixture can be in the range of 0.4 kWh / kg to 1.0 kWh / kg or any sub-range thereof, such as 0.4 kWh / kg to 0.6 kWh / kg.

[0072] As an example, an ultrasonic bath mixer can be used. As another example, a probe sonicator can be used. Probe sonication can be significantly more powerful and effective when compared to an ultrasonic bath for nanoparticle applications. The high shear forces generated by ultrasonic cavitation have the ability to break up particle aggregates and produce smaller and more uniform particle sizes. In addition to this, sonication can achieve a stable and uniform suspension of solids in a slurry. Typically, this causes dispersion and depolymerization of the solids and other breakdown. Examples of probe sonication devices include the Q-Series probe sonicators that are commercially available from QSonica LLC, Newtown, Connecticut. Another example includes the Branson Digital SFX-450 sonicator that is commercially available from Thomas Scientific, Swedesboro, New Jersey.

[0073] The local properties of each probe within the probe assembly may occasionally result in non-uniform mixing and suspension. This may be the case for, for example, large sample situations. This can be addressed by using a setup with a continuous flow cell and proper mixing. For example, with such a setup, mixing of the slurry will achieve a reasonably uniform dispersion.

[0074] Once processed, the initial slurry can have a viscosity in the range of 5,000 cps to 25,000 cps or any sub-range thereof (e.g., 6,000 cps to 19,000 cps).

[0075] The viscosity can be measured at 25 °C at a shear rate of 0.1 s -1 to 100 s -1 using a suitable commercial rheometer such as a TA Instruments model HR10.

[0076] At an optional step 630 (e.g., if no binder was added in step 610), a binder or additional binder can be applied as the surface treatment can form, in whole or in part, on the conductive material (e.g., high aspect ratio carbon elements) in the initial slurry. In some embodiments, at this stage, the surface treatment can self-assemble.

[0077] The resulting surface treatment can contain functional groups or other features, as described in further steps below, that can promote adhesion between the high aspect ratio carbon elements and the active material particles. For example, the functional groups on the binder can provide the surface treatment described.

[0078] At 640, the active material particles can be combined with the initial slurry to form a final slurry that contains the active material particles together with the high aspect ratio carbon elements having a surface treatment formed thereon.

[0079] The active material can be added directly to the initial slurry. Alternatively, the active material can first be dispersed in a solvent (e.g., water, alcohol, or a combination thereof, using the techniques described above for the initial solvent) to form an active material slurry. Then, the active material slurry can be combined with the initial slurry to form the final slurry.

[0080] At 650, the final slurry is processed to ensure good dispersion of the solid materials in the final slurry. Any suitable mixing process known in the art can be used. For example, the processing can use the techniques described above for 620. Alternatively, a planetary mixer, such as a multi-axis (e.g., three-axis or more) planetary mixer, can be used. The planetary mixer can be characterized by a plurality of blades, such as two or more mixing blades and one or more (e.g., two, three, or more) dispersion blades, such as disk dispersion blades.

[0081] During 650, due to the interaction between the surface treatment (e.g., binder) and the active material promoting the self-assembly process, the matrix entangled with the active material can self-assemble completely or partially.

[0082] In some embodiments, once processed, the final slurry will have a viscosity of 1,000 cps to 10,000 cps or any sub-range thereof (e.g., 2,500 cps to 6,000 cps).

[0083] At 660, the active layer 106 is formed from the final slurry. In some embodiments, the final slurry can be directly wet cast onto the current collector conductive layer 102 (or optional adhesion layer 104) and dried. As an example, casting can be performed by applying at least one of heat and vacuum until substantially all of the solvent and any other liquid have been removed, thereby forming the active layer 106. It may be desirable to protect various portions of the underlying layer. For example, in the case where the electrode 100 is intended for single-sided operation, it may be desirable to protect the underside of the conductive layer 102. Protection can include, for example, protecting from the solvent by masking certain areas or providing a drainage device to direct the solvent away.

[0084] In another example, the final slurry can be at least partially dried elsewhere and then transferred to the adhesion layer 104 or the conductive layer 102 using any suitable technique (e.g., roll-to-roll layer application) to form the active layer 106. As another example, the wet combined slurry can be placed on an intermediate material having a suitable surface and dried to form a layer (e.g., the active layer 106). Although any material having a suitable surface can be used as the intermediate material, exemplary intermediate materials include PTFE because its properties facilitate subsequent removal from the surface. The layer can be formed in a press to provide a layer exhibiting the desired thickness, area, and density.

[0085] In yet another example, the final slurry can be formed into a sheet and suitably coated onto the adhesion layer 104 or the conductive layer 102. For example, the final slurry can be applied through a slot die to control the thickness of the applied layer. As another example, the slurry can be applied and then leveled to the desired thickness, for example, using a doctor blade. A variety of other techniques can be used to apply the slurry. For example, coating techniques can include, but are not limited to: comma coating; reverse comma coating; doctor blade coating; slot die coating; direct gravure coating; air knife coating; chamber doctor blade coating; offset gravure coating; single-pass roll kiss coating; reverse kiss coating with a small diameter gravure roll; rod coating; three-pass reverse roll coating (top feed); three-pass reverse roll coating (feed die); reverse roll coating, etc.

[0086] The viscosity of the final slurry can vary according to the application technique. For example, for comma coating, the viscosity can be in the range of about 1,000 cps to about 200,000 cps. Lip die coating provides coating of a slurry having a viscosity of about 500 cps to about 300,000 cps. Reverse kiss coating provides coating of a slurry having a viscosity between about 5 cps and 1,000 cps. In some applications, the corresponding layer can be formed by multiple passes.

[0087] If desired, the active layer 106 formed from the final slurry can be compressed (e.g., using calendering equipment) before or after being applied to the electrode 100. The slurry can be partially or fully dried (e.g., by applying heat, vacuum, or a combination thereof) before or during the compression process. For example, in some embodiments, the active layer can be compressed to a final thickness that is less than 90%, 80%, 70%, 50%, 40%, 30%, 20%, 10%, or less of its thickness before compression (e.g., in a direction perpendicular to the current collector layer 102).

[0088] When a partially dried layer is formed during the coating or compression process, the layer can subsequently be fully dried (e.g., by applying heat, vacuum, or a combination thereof). In some embodiments, substantially all of the solvent is removed from the active layer 106.

[0089] The solvent used to form the slurry can be recovered and recycled into the slurry preparation process.

[0090] The active layer 106 can be compressed, for example, to break some of the constituent high aspect ratio carbon elements or other carbon-containing materials to increase the surface area of the corresponding layer. This compression treatment can increase one or more of the adhesion between layers, the ion transport rate within the layer, and the surface area of the layer. In various embodiments, the compression can be applied before or after applying or forming the corresponding layer onto the electrode 100.

[0091] In the case of using calendering to compress the active layer 106, the calendering equipment can be set to a gap spacing equal to less than 90%, 80%, 70%, 50%, 40%, 30%, 20%, 10% or less of the thickness of the layer before compression (e.g., set to about 33% of the thickness of the layer before compression). The calendering roll can be configured to provide a suitable pressure, such as greater than 1 ton / cm of roll length, greater than 1.5 ton / cm of roll length, greater than 2.0 ton / cm of roll length, greater than 2.5 ton / cm of roll length or greater. The compressed active layer can have a density in the range of 1 g / cc to 10 g / cc or any sub-range thereof (such as 2.2 g / cc (grams per cubic centimeter) to 4.0 g / cc). The calendering process can be carried out at a temperature in the range of 20 °C to 140 °C or any sub-range thereof. In some embodiments, the active layer 106 can be preheated (e.g., at a temperature in the range of 20 °C to 100 °C or any sub-range thereof) before calendering.

[0092] Process 600 can include any one of the following features (individually or in any suitable combination):

[0093] The initial slurry has a solids content in the range of 0.1 wt% to 20.0 wt% (or any sub-range thereof), and / or the final slurry has a solids content in the range of 10.0 wt% to 80 wt% (or any sub-range thereof).

[0094] As described, the conductive and binder scaffold or matrix can hold the active material particles together to form a cohesive layer that is also firmly attached to the metal current collector. Such an active material structure can be produced during slurry preparation and subsequently during roll-to-roll ("R2R") coating and drying processes. One of the main advantages of this technique is its scalability and "drop-in" nature, as various embodiments are compatible with conventional electrode manufacturing processes.

[0095] The techniques described herein can be used to form the matrix during slurry preparation: the high aspect ratio carbon materials are properly dispersed, and as needed, for example, as described above with respect to Figure 2The techniques described in process 600 are used for chemical functionalization. The chemical functionalization is designed to form an organized self-assembled structure on the surface of the active material particles (e.g., NMC particles for the cathode, or silicon particles ("Si") or silicon oxide ("SiOx") particles in the case of the anode). The slurry thus formed can be based on water and / or alcohol solvents for the cathode and water for the anode, and such solvents are very easy to evaporate and handle during the manufacturing process. Electrostatic interactions promote the self-organized structure in the slurry, and after the drying process, the binding between the carbon matrix with the active material particles and the surface of the current collector is promoted through surface treatment (e.g., functional groups on the matrix) and strong entanglement of the active material in the carbon matrix.

[0096] By adjusting the entanglement effect through surface functionalization, the mechanical properties of the electrode can be varied according to the application and mass loading requirements.

[0097] After coating and drying, the electrode can undergo a calendaring step to control the density and porosity of the active material. In the NMC cathode electrode, a density of 3.5 g / cc or greater and a porosity of 20% or greater can be achieved. The porosity can be optimized according to the mass loading and battery requirements of the lithium-ion battery. For anodes based on silicon oxide or silicon, the porosity can be specifically controlled to accommodate the expansion of the active material during the lithiation process.

[0098] The teachings herein can provide a reduction of up to about 20% in $ / kWh. By using water, alcohol, or a mixed water / alcohol as the solvent, which is easy to evaporate, the electrode production rate can be higher, and more importantly, the energy consumption of the long dryer can be significantly reduced. The conventional recovery system required when using NMP or similar compounds as the solvent is also greatly simplified when using water, alcohol, or their combination.

[0099] The teachings herein provide an active layer with a 3D matrix, which can significantly increase the electrode conductivity by 10 to 100 times compared to electrodes using conventional binders such as PVDF, enabling fast charging at the battery level. Using this technique, thick electrode coatings in the cathode can reach 150 μm (or more) on each side of the current collector. The solvent used in the slurry in combination with the strong 3D carbon matrix is designed to achieve thick wet coatings without cracking during the drying step. Thick cathodes with high-capacity anodes can achieve a significant jump in energy density up to 400 Wh / kg or higher.

[0100] Energy storage device

[0101] Once the electrode 100 has been assembled, the electrode 100 can be used to assemble an energy storage device. The assembly of the energy storage device can follow conventional steps for assembling the electrode with a separator and placing them within an enclosure (e.g., a can or a pouch), and can also include additional steps for adding an electrolyte and sealing the enclosure.

[0102] One exemplary embodiment includes a lithium-ion battery energy storage device in the form of a pouch cell that combines a Ni-rich NMC active material in the cathode with a SiOx and graphite blend active material in the anode, where both the anode and the cathode are fabricated using the 3D carbon matrix process as described herein.

[0103] Figure 3 A schematic diagram of an electrode arrangement of an example of a pouch cell device is shown. As shown, a cathode active layer 760 (e.g., an active layer according to various embodiments disclosed herein) is on the opposite side of a current collector 710 (e.g., an aluminum foil current collector) to form a bi-sided cathode disposed between two single-sided anodes. Each single-sided anode has an anode layer 740 or 750 (e.g., an active layer including a network of carbon elements such as those disclosed herein) disposed on a current collector 720 or 730 (e.g., a copper current collector). The electrodes are separated by a permeable separator material 780 wetted with an electrolyte (not shown). This arrangement can be housed in a pouch cell of a type known in the art.

[0104] In Figure 4 a cross-section of an energy storage device (ESD) 810 is shown. The energy storage device (ESD) 810 includes an enclosure 811. The enclosure 811 has two terminals 800 disposed on its exterior. The terminals 800 provide an internal electrical connection to a storage element 812 housed within the enclosure 811 and an external electrical connection to an external device such as a load or a charging device (not shown). The energy storage devices disclosed herein can be batteries, capacitors, supercapacitors, etc.

[0105] Embodiment

[0106] Embodiment 1 :

[0107] The solubility of a copolymer of methacrylic acid and methyl methacrylate in ethanol was tested and found to be soluble in an amount greater than 10 wt% based on the total weight of the solution.

[0108] Embodiment 2 (hypothetical) :

[0109] A solution of a copolymer having a polymer concentration of 10 wt% in water, alcohol, or a combination thereof (such as from Example 1) is combined with a slurry of a conductive polymer in water, alcohol, or a combination thereof, an active material, and an additional solvent (water, alcohol, or both). Based on the dry weight (i.e., excluding the weight of water and alcohol), the amount of the copolymer in the mixture is 1%. Additional mixing occurs. The slurry is coated onto a metal foil and dried.

[0110] The present disclosure also encompasses the following aspects.

[0111] Aspect 1: An electrode comprising a current collector and an active layer on the current collector, wherein the active layer comprises electrode active particles, a conductive material, and a binder, wherein the binder comprises a copolymer comprising a first repeating unit and a second repeating unit; wherein the first repeating unit is derived from the polymerization of a first monomer, the first monomer being an ethylenically unsaturated monomer having a hydrophilic side group, and the second repeating unit is derived from the polymerization of a second monomer having ethylenic unsaturation.

[0112] Aspect 2: The electrode according to Aspect 1, wherein the hydrophilic side group comprises a carboxylic acid group, a carboxylate group, an acetate group, an ester group, a nitrile group, a hydroxyl group, or an amide group.

[0113] Aspect 3. The electrode according to Aspect 1 or 2, wherein the first repeating unit has the following formula:

[0114]

[0115] where P is -LCOOR 1 , where R 1 is H, a monovalent metal ion (such as Na + , K + or Li + ), or a hydrocarbon group having 1 to 3 carbon atoms, preferably R 1 is H or a monovalent metal;

[0116] -LC(O)N(R 2 ), where R 2 is independently H or an alkyl group having 1 to 3 carbon atoms, preferably 1 carbon atom, each time it appears; or -LOC(O)-R 3 , where R 3 is H or an alkyl group having 1 to 3, preferably 1 carbon atom; LCN; or -LOH, where L is independently a direct bond or a hydrocarbon group having 1 to 3 carbon atoms, preferably L is a direct bond each time it appears; preferably P is -COOR 1 , where R 1is a monovalent metal ion or H; and R is independently, each time it appears, H, an alkyl group of 1 to 3 carbon atoms, or one of the Rs can be P as defined below, preferably R is H;

[0117] and the second repeating unit has the following formula:

[0118]

[0119] wherein R' is independently, each time it appears, H; a hydrocarbon of 1 to 3 carbon atoms, such as methyl; -LCOOR 4 , where R 4 is a hydrocarbon group of 1 to 3 carbon atoms; -LCN, where L is independently, each time it appears, a direct bond or a hydrocarbon group of 1 to 3 carbon atoms, preferably L is a direct bond each time it appears; or a 4-, 5- or 6-membered lactam ring bonded to the main chain of the repeating unit through a nitrogen atom, preferably at least three of the R's are H, and the fourth R' is a hydrocarbon of 1 to 3 carbon atoms, such as methyl; -COOR 4 , where R 4 is a hydrocarbon group of 1 to 3 carbon atoms; or a 4-, 5- or 6-membered lactam ring bonded to the main chain of the repeating unit through a nitrogen bond, provided that R' is different from P in the A repeating unit.

[0120] Aspect 4. The electrode according to aspect 3, wherein three of the R's are hydrogen, and one R' has the following structure:

[0121]

[0122] Aspect 5. The electrode according to any one of the preceding aspects, wherein the hydrophilic side group includes a carboxylic acid or its salt.

[0123] Aspect 6. The electrode according to any one of the preceding aspects, wherein the conductive elements form a network.

[0124] Aspect 7. The electrode according to any one of the preceding aspects, wherein the conductive element is a high aspect ratio carbon element.

[0125] Aspect 8. The electrode according to aspect 7, wherein the high aspect ratio carbon element comprises carbon nanotubes.

[0126] Aspect 9. An energy storage device, the energy storage device comprising an electrode according to any one of aspects 1 to 7.

[0127] Aspect 10. The energy storage device according to aspect 9, wherein the energy storage device is a pouch cell device.

[0128] Aspect 11. The energy storage device according to aspect 9 or 10, the energy storage device includes a bilateral cathode disposed between two unilateral anodes, wherein at least one of the cathode or the anode is an electrode according to any one of claims 1 to 6.

[0129] Aspect 12: The energy storage device according to any one of aspects 9 to 11, the energy storage device includes an electrolyte between two electrodes, for example, between the cathode and the anode.

[0130] Aspect 13: The energy storage device according to any one of aspects 9 to 12, the energy storage device further includes a permeable separator material between the electrodes, for example, between the cathode and the anode.

[0131] Aspect 14: The energy storage device according to any one of aspects 9 to 13, the energy storage device includes a housing.

[0132] Aspect 15: The energy storage device according to aspect 14, the energy storage device further includes one terminal, preferably two terminals, on the outside of the housing to provide electrical connection to the electrodes.

[0133] Aspect 16: A method of making an electrode according to any one of aspects 1 to 8, the method includes: providing a slurry containing a conductive element, a binder, and an electrode active material, the slurry in water, alcohol, or a combination thereof, and coating the slurry onto a current collector, and drying to remove the solvent.

[0134] All ranges disclosed herein include endpoints, and the endpoints can be combined with each other independently (e.g., the range "up to 25 wt%, or more specifically, 5 wt% to 20 wt%" includes the endpoints and all intermediate values of the range "5 wt% to 25 wt%", etc.). In addition, the upper and lower limits can be combined to form a range (e.g., "at least 1 wt% or at least 2 wt%" and "up to 10 wt% or 5 wt%" can be combined into the range "1 wt% to 10 wt%", or "1 wt% to 5 wt%", or "2 wt% to 10 wt%", or "2 wt% to 5 wt%").

[0135] The present disclosure may alternatively include any suitable components disclosed herein, consist of or consist essentially of the same. The present disclosure may additionally or alternatively be formulated to be free of or substantially free of any components, materials, ingredients, adjuvants or substances used in prior art compositions or not necessary for achieving the functions or objectives of the present disclosure.

[0136] All cited patents, patent applications, and other references are hereby incorporated by reference in their entirety. However, if a term in this patent application conflicts or collides with a term in an incorporated reference, the term from this patent application shall control over the conflicting term from the incorporated reference.

[0137] Unless otherwise indicated herein, all test standards are the latest standards in effect as of the filing date of this application, or, if priority is claimed, the filing date of the earliest priority application in which the test standard appears.

Claims

1. An electrode, the electrode comprising a current collector, and an active layer on the current collector, wherein the active layer comprises electrode active particles, a conductive material, and a binder, wherein the binder comprises a copolymer, the copolymer comprising a first repeating unit and a second repeating unit; wherein the first repeating unit is derived from the polymerization of a first monomer, the first monomer being an ethylenically unsaturated monomer having a hydrophilic side group, and the second repeating unit is derived from the polymerization of a second monomer having ethylenic unsaturation.

2. The electrode according to claim 1, wherein the hydrophilic side group comprises a carboxylic acid group, a carboxylate group, an acetate group, an ester group, a nitrile group, or a hydroxyl group, or an amide group.

3. The electrode according to claim 1 or 2, wherein the first repeating unit has the following formula: where P is -LCOOR 1 , where R 1 is H, a monovalent metal ion or a hydrocarbon group having 1 to 3 carbon atoms; -LC(O)N(R 2 )2, where R 2 is, independently at each occurrence, H or an alkyl group having 1 to 3 carbon atoms; -LOC(O)-R 3 , where R 3 is H or an alkyl group having 1 to 3 carbon atoms; -LCN; or -LOH, wherein L is independently, each time it appears, a direct bond or a hydrocarbon group of 1 to 3 carbon atoms; and R is independently, each time it appears, H, an alkyl group of 1 to 3 carbon atoms, or one of the Rs can be P; and the second repeating unit has the following formula: wherein each occurrence of R' is independently H; a hydrocarbon having 1 to 3 carbon atoms; -LCOOR 4 , where R 4 is a hydrocarbon group having 1 to 3 carbon atoms; -LCN, or a 4-, 5- or 6-membered lactam ring bonded to the main chain of the repeating unit through a nitrogen atom, where L is a direct bond or a hydrocarbon group having 1 to 3 carbon atoms, provided that R' is different from P in the A repeating unit.

4. The electrode according to claim 3, wherein three R's are hydrogen, and one R' has the following structure:

5. The electrode according to any one of the preceding claims, wherein the hydrophilic side group comprises a carboxylic acid or its salt.

6. The electrode according to any one of the preceding claims, wherein the conductive elements form a network.

7. The electrode according to any one of the preceding claims, wherein the conductive element is a high aspect ratio carbon element.

8. The electrode according to claim 7, wherein the high aspect ratio carbon element comprises carbon nanotubes.

9. An energy storage device, the energy storage device comprising an electrode according to any one of claims 1 to 7.

10. A method of making an electrode according to any one of claims 1 to 8, the method comprising providing a slurry comprising the conductive element, the binder, and an electrode active material, the slurry in water, an alcohol, or a combination thereof; and coating the slurry onto a current collector and drying to remove the solvent.

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