Electrodes for energy storage devices comprising copolymer binders

Abstract

An electrode useful in an energy storage device includes a current collector and an active layer on the current collector, the active layer including electrode active particles, a conductive material, and a binder, the binder including a copolymer including first repeat units and second repeat units, the first repeat units derived from polymerization of a first monomer that is an ethylenically unsaturated monomer having a hydrophilic pendant group, and the second repeat units derived from polymerization of a second monomer having ethylenic unsaturation.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Patent Application No. 63 / 417,124, filed October 18, 2022, which is incorporated herein by reference in its entirety.

[0002] FIELD OF THE INVENTION The present invention relates to energy storage devices, particularly ultracapacitors and lithium ion batteries, and electrodes used therein. [Background technology]

[0003] Lithium batteries are used in many products, including medical devices, electric vehicles, airplanes, and consumer products such as laptop computers, cell phones, and cameras. Due to their high energy density, high operating voltage, and low self-discharge, lithium-ion batteries have overtaken the secondary battery market and continue to find new applications in products and evolving industries.

[0004] Generally, a lithium ion battery ("LIB" or "LiB") includes an anode, a cathode, and an electrolyte material, such as an organic solvent containing a lithium salt. More specifically, the anode and cathode (collectively "electrodes") are formed by mixing either the anode or cathode active material with a binder and a solvent to form a paste or slurry, which is then coated onto a current collector, such as aluminum or copper, and dried to form a film on the current collector. The anode and cathode are then layered or coiled before being housed within a pressurized casing containing the electrolyte material, all of which together form the lithium ion battery.

[0005] The binder serves to adhere the active material to the current collector with a suitable coating. It is important that the binder facilitates maintaining good contact between the active material and the current collector. Furthermore, it was 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 battery charging and discharging. The binder must also be strong enough to withstand the manipulation of the electrode when it is fitted into the battery casing.

[0006] Therefore, binders such as cellulosic binders or cross-linked polymer binders have been used to provide good mechanical properties, however, in conventional electrodes, the binders selected generally require environmentally unfriendly or toxic solvents for processing. Summary of the Invention

[0007] Disclosed herein is an electrode comprising: a current collector; and an active layer on the current collector, the active layer comprising electrode active particles, a conductive material, and a binder, the binder comprising a copolymer comprising first repeat units and second repeat units, wherein the first repeat units are derived from polymerization of a first monomer, the first monomer being an ethylenically unsaturated monomer having a hydrophilic pendant group, and the second repeat units are derived from polymerization of a second monomer having ethylenic unsaturation.

[0008] Also disclosed herein are energy storage devices comprising such electrodes.

[0009] Also disclosed herein is a method of making such an electrode, comprising providing a slurry comprising a conductive element, a binder, and an electrode active material in water, an alcohol, or a combination thereof, coating the slurry onto a current collector, and drying to remove the solvent. [Brief explanation of the drawings]

[0010] The following is a brief description of the drawings, in which like elements are numbered alike and which are presented for the purpose of illustrating exemplary embodiments disclosed herein, but not for the purpose of limiting same. [Figure 1] FIG. 1 is a diagram of an example of an electrode disclosed herein. [Figure 2] 1 is a flow chart illustrating an example of a method that may be used to fabricate the electrodes disclosed herein. [Figure 3] FIG. 1 is a diagram of electrode placement in a pouch cell device. [Figure 4] 1 is a schematic cross-sectional depiction showing an embodiment of an energy storage device (ESD). DETAILED DESCRIPTION OF THE INVENTION

[0011] A more complete understanding of the components, processes, and apparatus disclosed herein can be obtained by reference to the accompanying drawings. These figures are merely schematic representations based on convenience and ease of illustrating the disclosure and, as such, are not intended to indicate the relative sizes and dimensions of the devices or their 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 structures of the embodiments selected for illustration in the drawings and are not intended to define or limit the scope of the disclosure. It should be understood that in the drawings and the following description, like numerical designations refer to components of similar function.

[0012] Disclosed herein is an electrolysis cell that includes a housing containing electrodes (anode and cathode). The housing contains an electrolyte in contact with the anode and cathode. Both electrodes (anode and cathode) include current collectors on which an active layer is disposed. The active layer may be disposed on an optional adhesive layer that contacts the electrodes.

[0013] 1 is a diagram of an example of an electrode (anode or cathode) 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. By way of example, adhesion layer 104 includes a material that promotes adhesion between current collector 102 and active layer 106. Active layer 106 includes electrode active material 110 in a binder and conductive elements 108. The conductive elements can include high aspect ratio elements.

[0014] The current collector 102 is a conductive element. The current collector can include a metal (e.g., a substantially pure metal or a metal alloy). As another example, the current collector 102 can be in the form of a metal strip or foil. For example, the current collector 102 can be an aluminum foil or strip, an aluminum alloy foil or strip, a copper foil or strip, or a copper alloy foil or strip. The current collector 102 can have a thickness of 15 μm (micrometers) or less, 10 μm or less, 8 μm or less, or 5 μm or less. In some embodiments, the current collector can have a thickness of at least 3 μm. For example, the current collector 102 can have a thickness of 3 to 15 μm, or between 6 μm and about 8 μm. As another example, the current collector 102 is an aluminum foil or aluminum alloy foil having a thickness of 5 to 7 μm.

[0015] The active layer 106 includes a conductive material, a binder material, and an electrode active material. The active layer can be made by mixing the conductive material, the binder material, and the electrode active material with a solvent to form a mixture. The mixture can be applied directly to a current collector or onto an adhesive layer that can adhere to the current collector. If an adhesive layer is used, it can be conductive. The mixture can be dried to remove the solvent and leave a solid active layer.

[0016] Conductive element The conductive elements (also referred to as conductive materials) can include carbon. For example, the conductive elements can be high aspect ratio carbon elements. The term "high aspect ratio carbon elements" refers to carbonaceous elements having a size in one or more dimensions ("major dimensions") that is significantly larger than the size of the element in the transverse dimension ("minor dimension"). The high aspect ratio carbon elements can include a substantially cylindrical network of carbon atoms. The conductive material can include carbon nanotubes or bundles of carbon nanotubes.

[0017] The conductive material can form a conductive permeating network capable of transmitting current between any two separated points located on the surface of the solid active layer (without solvent therein). In other words, current can be transmitted from one surface or end of the active layer to the opposite surface or end by physical contact or electron hopping between the conductive elements in the electrode active layer. The permeating 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 substantially oriented within the electrode active layer 106 in a direction substantially parallel to the current collector, facilitating current conduction from one end of the electrode to the other while still maintaining some reduced orientation through the thickness of the active layer.

[0018] The conductive material can be present in the mixture in an amount of 0.1 to 1.3, or 0.15 to 1.2, or 0.3 to 1 weight percent, based on the total weight of the mixture (the mixture including the conductive material, electrode active material, binder material, and solvent). The conductive material can be present in the active layer in an amount of 0.2 to 3.5, or 0.3 to 3, or 0.5 to 2 weight percent, based on the total weight of solids in the active layer (the total weight of solids excludes solvent and includes the conductive material, binder material, and electrode active material).

[0019] The high aspect ratio carbon elements can be single wall carbon nanotubes (SWCNTs), multiwall carbon nanotubes (MWNTs), or a mixture of both.

[0020] The single-walled carbon nanotubes can have an outer diameter of 0.5 to 5.0 nanometers, preferably 1.0 to 3.5 nanometers. The single-walled carbon nanotubes can have an aspect ratio (length to diameter ratio) of greater than about 2.0, preferably greater than 5.0, preferably greater than 10.0, greater than 50, and more preferably greater than 100. In an exemplary embodiment, the single-walled carbon nanotubes can have an average aspect ratio of 5 to 200.

[0021] The single-walled carbon nanotubes can have a length of 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, more preferably greater than 15 micrometers, up to at least 200 micrometers. In an exemplary embodiment, the single-walled carbon nanotubes can have an average length of 10 nanometers to 20 micrometers, preferably 20 nanometers to 15 micrometers.

[0022] The single-walled carbon nanotubes can be present in the mixture of the conductive material, binder material, electrode active material, and solvent in an amount of 0.1 to 2 weight percent, based on the total weight of the mixture. For example, the amount of single-walled nanotubes in the mixture can be 0.1 to 0.3, or 0.15 to 9.25 weight percent. As another example, the amount of single-walled nanotubes in the mixture can be 0.4 to 2 weight percent.

[0023] The single-walled carbon nanotubes can be present in the electrode active layer (the conductive material, binder material, and electrode active material excluding the solvent) in an amount of 0.2 to 4 weight percent (wt %), based on the total weight of the electrode active layer. For example, the amount of single-walled nanotubes in the electrode active layer can be 0.2 to 0.6, or 0.3 to 0.5 wt %. As another example, the amount of single-walled nanotubes in the electrode active layer can be 0.5 to 4 wt %.

[0024] The number of carbon layers in a multi-walled carbon nanotube can be 2 or more, 5 or more, 10 or more, or 50 or more. Multi-walled carbon nanotubes can contain an average of 3 to 15 layers, 4 to 12 layers, 5 to 10 layers, or 6 to 8 layers.

[0025] The active layer 106 can include multi-walled carbon nanotubes and single-walled carbon nanotubes. The multi-walled carbon nanotubes swell more than single-walled carbon nanotubes when wetted by an electrolyte in an energy storage device in which the electrode 100 is located. For example, the multi-walled carbon nanotubes can swell at least 15%, or at least 25%, or at least 50% more than single-walled carbon nanotubes when wetted by an electrolyte in an energy storage device in which the electrode 100 is located. For example, the length of the multi-walled carbon nanotubes can expand at least 15%, or at least 25%, or at least 50% more than the length of single-walled carbon nanotubes when wetted by the electrolyte. As another example, the multi-walled carbon nanotubes swell up to 50% when wetted (e.g., the length of the multi-walled carbon nanotubes increases by 50% after wetting with the electrolyte and / or the diameter of the multi-walled carbon nanotubes increases by 50% after wetting).

[0026] The multi-walled carbon nanotubes can have an outer diameter of 2.0 to 50 nanometers, 5.0 to 40 nanometers, or 6 to 10 nanometers. The multi-walled carbon nanotubes can have a length of 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, the multi-walled carbon nanotubes can have an average length of up to 25 micrometers or up to 20 micrometers. In exemplary embodiments, the single-walled carbon nanotubes have an average length of 10 nanometers to 20 micrometers or 20 nanometers to 15 micrometers. The multi-walled carbon nanotubes can have an aspect ratio (length-to-diameter ratio) of greater than 5.0, greater than 10.0, greater than 50, greater than 100, or greater than 500.

[0027] The electrode includes multi-walled carbon nanotubes that can be relatively long compared to multi-walled carbon nanotubes contained in prior 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 output 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. Therefore, 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 it is merely a particle of carbon without entanglements such as those exhibited by a set of multi-walled carbon nanotubes. An indication that a certain amount of multi-walled carbon nanotubes has a length exceeding a threshold length and therefore has sufficient swelling properties is observed during the calendering process, where a relatively large amount of pressure or effort to calender the slurry in connection with application to the foil indicates that the collective swelling (e.g., average swelling) of the multi-walled carbon nanotubes in the active layer meets a certain performance threshold. However, multi-walled carbon nanotubes are generally difficult to process.

[0028] Processing of multi-walled carbon nanotubes in connection with the preparation / formation of the active layer and / or electrode is gentler than processes for prior art electrodes. As such, processes according to various embodiments preserve longer multi-walled carbon nanotubes (e.g., fewer crushed, fragmented, or destroyed multi-walled carbon nanotubes). In some embodiments, the active layer of the electrode includes a set of multi-walled carbon nanotubes having an average length longer 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 skewed toward the nominal length of the multi-walled carbon nanotubes. In one example, the nominal length of the multi-walled carbon nanotubes is about 16 micrometers. For example, the multi-walled carbon nanotubes are treated and / or adapted to reduce or minimize breakage or fracture of the multi-walled carbon nanotubes. The lengths of the multi-walled carbon nanotubes in a network of high aspect ratio carbon elements are generally the nominal length of the multi-walled carbon nanotubes, or the lengths of such multi-walled carbon nanotubes tend to be more skewed relative to the nominal length. In some embodiments, at least 75% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements are within 10% of their nominal length (e.g., 13.4 micrometers to about 15 micrometers). In some embodiments, at least 75% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements have a length of at least 12 micrometers. In some embodiments, at least 75% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements have a length of at least 13 micrometers. In some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements are within 10% of their nominal length (e.g., 13.4 micrometers to about 15 micrometers). In some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements have a length of at least 12 micrometers.In some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements have a length of at least 8 micrometers, hi some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements have a length of at least 13 micrometers.

[0029] According to various embodiments, the distribution of lengths of a set of multi-walled carbon nanotubes is skewed toward the nominal length of the multi-walled carbon nanotubes. For example, the multi-walled carbon nanotubes are treated and / or adapted to reduce or minimize breakage or fracture of the multi-walled carbon nanotubes. The lengths of the multi-walled carbon nanotubes in a network of high aspect ratio carbon elements are generally at the nominal length of the multi-walled carbon nanotubes, or the lengths of such multi-walled carbon nanotubes tend to be more skewed relative to the nominal length.

[0030] In some embodiments, at least 75% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements are within 10% of their nominal length (e.g., 13.4 micrometers to about 15 micrometers). In some embodiments, at least 75% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements have a length of at least 12 micrometers. In some embodiments, at least 75% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements have a length of at least 13 micrometers. In some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements are within 10% of their nominal length (e.g., 13.4 micrometers to about 15 micrometers). In some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements have a length of at least 12 micrometers. In some embodiments, at least 50% of the multi-walled carbon nanotubes in the network of high aspect ratio carbon elements have a length of at least 13 micrometers.

[0031] The multi-walled carbon nanotubes can be present in the mixture (the mixture including the conductive material, the electrode active material, the binder material, and the solvent) in an amount of 0.3 to 1.0 weight percent, preferably 0.4 to 0.9 weight percent, based on the total weight of the mixture. The multi-walled carbon nanotubes are present in the solid anode active layer (the solid active layer including the conductive material, the binder material, and the electrode active material without the solvent) in an amount of 0.8 to 2.6 weight percent, preferably 1.0 to 1.8 weight percent, based on the total weight of the solid anode active layer.

[0032] In instances where both multi-walled and single-walled carbon nanotubes are used, the ratio of the weight of multi-walled carbon nanotubes to the weight of single-walled carbon nanotubes in the mixture or solid active material layer can be at least 2:1.

[0033] In one embodiment, the three-dimensional network of high aspect ratio carbon elements 108 includes carbon nanotubes, which may be multi-walled carbon nanotubes and / or fragments of such carbon nanotubes only.

[0034] In another example, the multi-walled carbon nanotubes are present in the mixture or solid anode active material layer in an amount at least twice the amount of single-walled carbon nanotubes, based on the weight of the conductive material.

[0035] The network of the three-dimensional network of high aspect ratio carbon elements 108 can comprise at least 99% carbon by weight.

[0036] The three-dimensional network of high aspect ratio carbon elements 108 can include an electrically interconnected network of carbon elements that exhibits connectivity above a percolation threshold, where the network defines one or more highly conductive pathways having lengths greater than 100 μm. The percolation threshold is the threshold at which conductive elements contact each other to provide a conductive network measured across any two points on any surface of the network.

[0037] electrode active material The active materials are typically different in the anode and cathode.

[0038] For example, the anode active material may 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 thereof, alloys of two or more of these, or alloys of these with other elements; oxides, carbides, nitrides, sulfides, phosphides, selenides, tellurides of these metals, and mixtures or lithium-containing complexes thereof; salts and hydroxides of Sn; lithium titanate, lithium manganate, lithium aluminate, lithium-containing titanium oxide, lithium transition metal oxide; prelithiated versions thereof; particles of Li, Li alloys, or surface-stabilized Li having at least 60% lithium by weight; or combinations thereof. The active material may include graphite instead of or in addition to the anode active material. For example, the anode active material may include silicon oxide and / or silicon carbon oxide. Such anode active materials comprising silicon oxide or silicon carbon oxide can further comprise graphite.

[0039] For example, the cathode active material can include lithium cobalt oxide (LCO, sometimes referred to as "lithium cobaltate" or "lithium cobaltite"). Examples of LCO formulations include LiCoO, lithium nickel manganese cobalt oxide (NMC, having a formula variant of LiNiMnCo), lithium manganese oxide (LMO, having a formula variant of LiMnO, LiMnO, etc., or combinations thereof), lithium titanate oxide (LTO, one variant of which is LiTiO), and lithium cobalt oxide (LCO). 12 Lithium iron phosphate oxide (LFP, one variant is LiFePO4), lithium nickel cobalt aluminum oxide (and its variants as NCA), and other similar other materials. Other variants of the foregoing may also be included.

[0040] When NMC is used as the active material, nickel-rich NMC can be used. For example, a variant of NMC is 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 more, 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 be lithium nickel manganese cobalt oxide (LiNi x Mn y Co z O2). Variations of this formula that can be used in the active material layer include NMC111 (discussed in more detail below), NMC532 (LiNi 0.5 Mn 0.3 Co 0.2 O2), NMC622(LiNi 0.6 Mn 0.2 Co 0.2 O2), or a combination thereof.

[0041] In embodiments, the active material used in both electrodes (anode and / or cathode) can also include a nickel-rich combination of nickel, manganese, and cobalt. Lithium-nickel-manganese-cobalt-oxide (LiNiMnCoO), abbreviated as NMC, offers high overall performance, excellent specific energy, and the lowest self-heating rate of all mainstream cathode powders. NMC powders may contain 20-40 wt. % nickel, 20-40 wt. % manganese, and 20-40 wt. % cobalt, based on the total weight of the NMC blend. While the term "NMC powder" can refer to various blends, it is desirable to use a blend containing 33 wt. % nickel, 33 wt. % manganese, and 33 wt. % cobalt. This blend, sometimes referred to as 1-1-1 (NMC111), is useful for applications with frequent cycling (automotive, energy storage) due to the reduced material cost resulting from the lower cobalt content and nickel-rich combination of nickel, manganese, and cobalt (NMC). The NMC powder may contain 20-40 wt. % nickel, 20-40 wt. % manganese, and 20-40 wt. % cobalt, based on the total weight of the NMC blend. While the term "NMC powder" can refer to various blends, it is desirable to use a blend containing 33 wt. % nickel, 33 wt. % manganese, and 33 wt. % cobalt. This blend, sometimes referred to as 1-1-1, is useful for applications with frequent cycling (automotive, energy storage) due to the reduced material cost resulting from the lower cobalt content. Lithium-nickel-manganese-cobalt-oxide (LiNiMnCoO2) offers strong overall performance, excellent specific energy, and the lowest self-heating rate of all mainstream cathode powders.

[0042] As described above, the active material can be contained or housed in a high aspect ratio active material network present in the electrode active layer. The active material can be present in the mixture used to form the electrode in an amount of 35 to 75 wt. %, preferably 40 to 70 wt. %, based on the total weight of the electrode mixture (the mixture used to prepare the electrode active layer, which contains the electrode polymer binder material, the electrode active material, the conductive material, and the solvent). The electrode active material is present in the electrode active layer (excluding the solvent) in an amount of 95 to 98.5 wt. %, based on the total weight of the cathode active layer.

[0043] Binder The binders described herein can provide the ability to fabricate electrodes using water and / or alcohol as a solvent. These binders can also provide good adhesive bond strength, good dispersion of slurry components (i.e., electrode active material, binder, and conductive material), and / or good stability during battery charging and discharging. The binders described herein can comprise, consist essentially of, 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 pendant groups on the copolymer binder that facilitate processing in at least water and / or alcohol and good dispersion of the slurry components while reducing the solubility of the binder in carbonate-based electrolytes. The second monomer can provide improved mechanical properties and / or electrochemical and chemical stability when used in energy storage devices (e.g., batteries, particularly lithium-ion batteries). Thus, the first monomer after polymerization can provide the polymer with hydrophilic pendant groups such as carboxylic acid groups, carboxylate groups, acetate groups, ester groups, nitrile groups, hydroxyl groups, or amide groups, which can improve solubility in water and / or alcohol, and the second monomer can provide flexibility to avoid stiffness that can cause cracking of the binder material.

[0044] The copolymer comprises a first repeat unit A and a second repeat unit B having distinct and different formulas. Unit A can be represented by the formula:

[0045] [ka] wherein R, independently in each occurrence, is H, an alkyl group of 1 to 3 carbon atoms, or one of R can be the same as P, as defined below. R can be H. P represents a hydrophilic pendant group. P can be -LCOOR 1 (In the formula, R 1 H, Na + , K. + , or Li + or a hydrocarbon group (preferably a divalent alkyl group) of 1 to 3 carbon atoms, preferably R 1 is H or a monovalent metal ion); -LC(O)N(R 2 )2(wherein, R 2 is independently in each occurrence H or an alkyl group of 1 to 3 carbon atoms, preferably 1 carbon atom; —OC(O)—R 3 (In the formula, R 3 is H or an alkyl group of 1 to 3, preferably 1, carbon atoms; -LCN; or LOH, where in each occurrence, L represents a direct bond or a divalent linking group, for example, 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 -COOR 1- is.

[0046] The unit B can be represented by the formula:

[0047] [ka] wherein R' is independently in each occurrence H; a hydrocarbon (preferably a divalent alkyl) group of 1 to 3 carbon atoms such as methyl; a nitrile group such as -CN; -LOH; LCOOR 4 (In the formula, R 4is a hydrocarbon group of 1 to 3 carbon atoms, L is a direct bond or a divalent linking group such as a hydrocarbon group of 1 to 3 carbon atoms, preferably a divalent alkyl group of 1 to 3 carbon atoms, L is preferably a direct bond; or a 4-, 5-, or 6-membered lactam ring attached to the backbone of the repeat unit through a nitrogen atom, preferably at least three of the R's are H. The remaining R's are hydrocarbon groups of 1 to 3 carbon atoms, such as methyl; -COOR 4 (In the formula, R 4 is a hydrocarbon group of 1 to 3 carbon atoms); or it can be a 4-, 5-, or 6-membered lactam ring attached to the backbone of the repeat unit through a nitrogen atom. When R' is a lactam ring, it preferably has the following structure:

[0048] [ka]

[0049] A copolymer can contain two or more different A repeat units or two or more different B repeat 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 repeat unit and a single type of B repeat unit, or a random copolymer of two different A repeat units and one or two types of B repeat units.

[0050] The copolymers can be made by known polymerization techniques for ethylenically unsaturated monomers, such as addition polymerization, which can be, for example, solution polymerization or emulsion polymerization.

[0051] Monomers that can be used to form repeat 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; ethylenically unsaturated amides such as tert-butyl methacrylate, acrylamide; ethylenically unsaturated diacids such as itaconic acid; ethylenically unsaturated nitriles such as acrylonitrile; and ethylenically unsaturated alcohols such as vinyl alcohol.

[0052] Monomers that can be used to form the repeat unit B include ethylenically unsaturated acetates such as vinyl acetate (provided that they are not used as A repeat units); ethylenically unsaturated esters such as vinyl esters, e.g., alkyl acrylates such as methyl methacrylate (provided that they are not used as A repeat units); ethylene; propylene; butylene; and vinylpyrrolidone. Ethylene and vinylpyrrolidone are preferred.

[0053] Specific examples of such copolymers include acrylic acid / vinylpyrrolidone copolymers (commercially available, for example, from Ashland Chemical under the trademark Ultrathix), vinyl acetate / vinylpyrrolidone copolymers (commercially available, for example, from Shanghai Dexiang Medicine Tech), ethylene / acrylic acid copolymers (commercially available, for example, from Dow Chemical, DuPont, or BASF), vinyl acetate / vinylpyrrolidone / itaconic acid terpolymers (commercially available, for example, from Dayang Chem (Hangzhou) Co. Ltd), methacrylic acid / methyl methacrylate copolymers (commercially available, for example, from Alfa Chemistry), acrylic acid / acrylonitrile copolymers, and methyl methacrylate / N,N-dimethylacrylamide copolymers.

[0054] The molar ratio of A repeat units to B repeat units can be 1:9 to 9:1, 2:8 to 8:2, 3:7 to 7:3, 4:6 to 6:4, or about 1:1.

[0055] The weight average molecular weight of the polymer, as determined by gel permeation chromatography, can be from 5,000 to 2,000,000 grams per mole, or from 10,000 to 1,000,000 grams per mole.

[0056] If desired, the polymer can contain crosslinkable functional groups or a crosslinking agent can be added so that the binder polymer can be crosslinked before fabrication of the electrode active layer is complete.

[0057] The polymer can be used as the only polymer in the binder. Alternatively, the polymer can be used in a blend with a second, different polymer. As yet another alternative, the polymer can be blended with one or more other known polymer binders. However, to maximize the value of the polymer, the additional polymer is preferably soluble or dispersible in water, alcohol, or a combination thereof. When used in a blend, the polymer preferably comprises at least 10, at least 20, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, at least 90, at least 95, or at least 99 weight percent of the blend, based on the total weight of the polymers in the blend.

[0058] Electrode formation An electrode can be produced by first preparing a mixture (sometimes referred to as a slurry) of conductive elements, active material, and binder in a solvent. An advantage of binders as described herein is that useful slurries can be formed using water, alcohol, or a combination thereof as the solvent. The slurry can then be coated directly onto a current collector or applied to a current collector with an intermediate adhesive layer.

[0059] The slurry can be prepared in a single step. Alternatively, the slurry can be prepared according to a multi-step process such as that shown in the flowchart of Figure 2, which illustrates an example process 600 for providing the electrode 100 of Figure 1. At 610, a conductive material, such as high aspect ratio carbon elements, and a surface treatment material (e.g., a surfactant, a binder material as described herein, or both) are combined with a solvent (e.g., water, alcohol, or a combination thereof) to form an initial slurry.

[0060] At 620, the initial slurry is treated to ensure good dispersion of the solid materials in the slurry. This treatment can include introducing mechanical energy into the mixture of solvent and solid materials (e.g., using an ultrasonicator, sometimes referred to as a "sonifier") or other suitable mixing device (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 more. For example, the mechanical energy introduced into the mixture per kilogram of mixture can be in the range of 0.4 kWh / kg to 1.0 kWh / kg, or any subrange thereof, such as 0.4 kWh / kg to 0.6 kWh / kg.

[0061] 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 ultrasonic baths for nanoparticle applications. The high shear forces generated by ultrasonic cavitation have the ability to break down particle agglomerates, resulting in smaller, more uniform particle sizes. Among other things, sonication can result in a stable and homogeneous suspension of solids in a slurry. Generally, this results in dispersion and deagglomeration and other breakdown of solids. An example of a probe sonication device is the Q Series Probe Sonicator available from QSonica LLC (Newtown, Connecticut). Another example is the Branson Digital SFX-450 sonicator available from Thomas Scientific (Swedesboro, New Jersey).

[0062] The localized nature of each probe within the probe assembly can sometimes result in non-uniform mixing and suspension. This can be the case, for example, with large samples. This can be addressed by using a setup with a continuous flow cell and appropriate mixing. For example, in such a setup, mixing of a slurry achieves a reasonably uniform dispersion.

[0063] The initial slurry, once processed, can have a viscosity in the range of 5,000 cps to 25,000 cps, or any subrange thereof, such as, for example, 6,000 cps to 19,000 cps.

[0064] Viscosity was measured at 25°C using a suitable commercially available rheometer such as the TA Instruments Model HR10, with a temperature of 0.1 to 100 s. -1 It can be measured at a shear rate of .

[0065] In optional step 630 (e.g., used if no binder was added in step 610), a binder or additional binder may be applied so that a surface treatment may be fully or partially formed on the conductive material (e.g., high aspect ratio carbon elements) in the initial slurry. In some embodiments, at this stage, the surface treatment may self-assemble.

[0066] The resulting surface treatment can include functional groups or other features that can promote adhesion between the high aspect ratio carbon elements and the active material particles, as described in further steps below. For example, functional groups on a binder can provide the surface treatment described above.

[0067] At 640, the active material particles can be combined with the initial slurry to form a final slurry containing the active material particles with the high aspect ratio carbon elements having the surface treatment formed thereon.

[0068] 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 with respect to the initial solvent) to form an active material slurry. The active material slurry can then be combined with the initial slurry to form the final slurry.

[0069] 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 may be used. For example, this processing may use the techniques described above with reference to 620. Alternatively, a planetary mixer, such as a multi-shaft (e.g., three or more) planetary mixer, may be used. The planetary mixer may feature multiple blades, for example, two or more mixing blades and one or more (e.g., two, three, or more) dispersion blades, such as a disk dispersion blade.

[0070] During 650, the matrix entangled with the active materials may fully or partially self-assemble as interactions between the surface treatment (eg, binder) and the active materials facilitate the self-assembly process.

[0071] In some embodiments, the final slurry, once processed, has a viscosity in the range of 1,000 cps to 10,000 cps, or any subrange thereof, for example, 2,500 cps to 6000 cps.

[0072] At 660, the active layer 106 is formed from the final slurry. In some embodiments, the final slurry may be wet cast directly onto the current collector conductive layer 102 (or optional adhesive layer 104) and dried. As an example, casting may form the active layer 106 by applying at least one of heat and vacuum until substantially all of the solvent and any other liquids are removed. It may be desirable to protect various portions of the underlying layers. For example, protecting the underside of the conductive layer 102 may be desirable if the electrode 100 is intended for double-sided operation. Protection may include, for example, protecting from the solvent by masking certain areas or providing a drain for removing the solvent.

[0073] In another example, the final slurry can be at least partially dried elsewhere using any suitable technique (e.g., roll-to-roll layer application) and then transferred onto adhesive layer 104 or conductive layer 102 to form active layer 106. In another example, the wet consolidated slurry can be placed onto an intermediate material having a suitable surface and dried to form a layer (e.g., active layer 106). While any material having a suitable surface can be used as the intermediate material, an exemplary intermediate material includes PTFE because its properties facilitate its subsequent removal from the surface. Layers can be formed in a press to provide a layer exhibiting a desired thickness, area, and density.

[0074] In yet another embodiment, the final slurry can be formed into a sheet and coated onto the adhesive layer 104 or the conductive layer 102, as appropriate. For example, the final slurry can be applied through a slot die to control the thickness of the applied layer. In another embodiment, the slurry can be applied and then leveled to the desired thickness using, for example, a doctor blade. Various other techniques can be used to apply the slurry. For example, coating techniques can include, but are not limited to, comma coating, comma reverse coating, doctor blade coating, slot die coating, direct gravure coating, air doctor coating (air knife), chamber doctor coating, offset gravure coating, one-roll kiss coating, reverse kiss coating with a small diameter gravure roll, bar coating, three reverse roll coating (top feed), three reverse roll coating (fountain die), reverse roll coating, etc.

[0075] The viscosity of the final slurry can vary depending on the application technique. For example, for comma coating, the viscosity can range from about 1,000 cps to about 200,000 cps. Lip die coating provides a coating with a slurry exhibiting a viscosity of about 500 cps to about 300,000 cps. Reverse kiss coating provides a coating with a slurry exhibiting a viscosity of about 5 cps to 1,000 cps. In some applications, each layer can be formed in multiple passes.

[0076] If desired, the active layer 106 formed from the final slurry may be compressed (e.g., using a calendaring device) before or after application to the electrode 100. The slurry may be partially or completely 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 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%, or 10% or less of its pre-compression thickness.

[0077] If a partially dried layer is formed during the coating or pressing process, the layer may then be completely dried (e.g., by applying heat, vacuum, or a combination thereof). In some embodiments, substantially all of the solvent is removed from the active layer 106.

[0078] The solvent used in forming the slurry can be recovered and recycled into the slurry making process.

[0079] The active layer 106 may be compressed, for example, to break down some of the constituent high aspect ratio carbon elements or other carbonaceous materials and increase the surface area of ​​each layer. This compression process may increase one or more of adhesion between the layers, ion transport rates within the layers, and surface area of ​​the layers. In various embodiments, compression may be applied before or after each layer is applied or formed into the electrode 100.

[0080] If calendering is used to compress the active layer 106, the calendering apparatus can be set with a gap spacing equal to less than 90%, 80%, 70%, 50%, 40%, 30%, 20%, 10%, or less of the pre-compression thickness of the layer (e.g., about 33% of the pre-compression thickness of the layer). The calender rolls can be configured to provide a suitable pressure, for example, greater than 1 ton per cm of roll length, greater than 1.5 tons per cm of roll length, greater than 2.0 tons per cm of roll length, greater than 2.5 tons per cm of roll length, or more. The compressed active layer can have a density in the range of 1 g / cc (grams per cubic centimeter) to 10 g / cc, or any subrange thereof, such as 2.2 g / cc 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 subrange thereof. In some embodiments, the active layer 106 can be preheated prior to calendering, for example, to a temperature in the range of 20° C. to 100° C., or any subrange thereof.

[0081] The process 600 may include any of the following features (individually or in any suitable combination).

[0082] The initial slurry has a solids content in the range of 0.1% to 20.0% by weight (or any subrange thereof), and / or the final slurry has a solids content in the range of 10.0% to 80% by weight (or any subrange thereof).

[0083] As mentioned above, a scaffold or matrix of conductive material and binder can hold the active material particles together to form a cohesive layer that is also strongly attached to the metal current collector. Such an active material structure can be created during slurry preparation and then in a roll-to-roll ("R2R") coating and drying process. One of the main advantages of this technology is its scalability and "drop-in" nature, as various embodiments are compatible with conventional electrode manufacturing processes.

[0084] The matrix can be formed during slurry preparation using the techniques described herein, in which the high-aspect ratio carbon material is appropriately dispersed and, if desired, chemically functionalized using, for example, the method described above with reference to process 600 in FIG. 2 . The chemical functionalization is designed to form an organized self-assembled structure with the surface of the active material particles, e.g., NMC particles for use in the cathode, or silicon ("Si") particles or silicon oxide ("SiOx") particles in the case of the anode. The slurry so formed can be based on water and / or alcohol solvents for the cathode and water for the anode, where such solvents are very easily evaporated and handled during the manufacturing process. Electrostatic interactions promote the self-assembled structure in the slurry, and after the drying process, bonding between the carbon matrix with the so-formed active material particles and the surface of the current collector is promoted by the surface treatment (e.g., functional groups on the matrix) and the strong entanglement of the active material in the carbon matrix.

[0085] The mechanical properties of the electrodes can be tailored depending on the application and mass loading requirements by tuning the surface functionalization versus the entanglement effect.

[0086] After coating and drying, the electrode can undergo a calendaring process to control the density and porosity of the active material. Densities of 3.5 g / cc or greater and porosities of 20% or greater can be achieved for NMC cathode electrodes. Porosity can be optimized depending on the mass loading and lithium-ion battery cell requirements. For silicon oxide or silicon-based anodes, porosity can be specifically controlled to accommodate the expansion of the active material during the lithiation process.

[0087] The teachings herein can provide up to a 20% reduction in $ / kWh. By using water, alcohol, or a water / alcohol mixture as the solvent, these solvents evaporate easily, allowing for higher throughput in electrode production, and more importantly, significantly reducing energy consumption from long dryers. The traditional recovery systems required when using NMP or similar compounds as the solvent are also greatly simplified when using water, alcohol, or a combination thereof.

[0088] The teachings herein provide an active layer with a 3D matrix that can dramatically increase electrode conductivity by 10 to 100 times compared to electrodes using conventional binders such as PVDF, enabling rapid charging at the battery level. This technology enables thick electrode coatings in the cathode, up to 150 μm thick per side (or more) of the current collector. The solvent used in the slurry, combined with the strong 3D carbon matrix, is designed to achieve a thick wet coating without cracking during the drying process. A thick cathode with a high-capacity anode enables a substantial leap in energy density, reaching 400 Wh / kg or more.

[0089] Energy Storage Devices Once the electrode 100 is assembled, it can be used to assemble an energy storage device. Assembly of the energy storage device may follow conventional steps used to assemble an electrode with a separator and place it into a housing, such as a canister or pouch, and may further include additional steps to add electrolyte and seal the housing.

[0090] One exemplary embodiment includes a pouch cell format Li-ion battery energy storage device that combines a Ni-rich NMC active material in the cathode and a SiOx and graphite blend active material in the anode, where both the anode and cathode are fabricated using the 3D carbon matrix process as described herein.

[0091] A schematic diagram of one example of an electrode arrangement for a pouch cell device is shown in FIG. 3. As shown, cathode active layers 760 (e.g., active layers according to various embodiments disclosed herein) on either side of a current collector 710 (e.g., an aluminum foil current collector) form a double-sided cathode disposed between two single-sided anodes. Each single-sided anode has an anode layer 740 or 750 (e.g., an active layer comprising a network of carbon elements as 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 by the electrolyte (not shown). This arrangement can be housed within a pouch cell of a type well known in the art.

[0092] 4 shows a cross section of an energy storage device (ESD) 810. The energy storage device (ESD) 810 includes a housing 811. The housing 811 has two terminals 800 disposed on its exterior. The terminals 800 provide an internal electrical connection to a storage cell 812 contained within the housing 811 and an external electrical connection to an external device, such as a load or charging device (not shown). The energy storage devices disclosed herein can be batteries, capacitors, ultracapacitors, etc. [Example]

[0093] Example 1: The solubility of the copolymer of methacrylic acid and methyl methacrylate was tested for solubility in ethanol and was found to be soluble in amounts greater than 10 weight percent, based on the total weight of the solution.

[0094] Example 2 (Prophetic): A copolymer solution (such as that from Example 1) in water, alcohol, or a combination thereof at a polymer concentration of 10 weight percent is combined with a slurry of conductive polymer, active material, and additional solvent (water, alcohol, or both) in water, alcohol, or a combination thereof. The amount of copolymer in the mixture is 1% based on dry weight (i.e., excluding the weight of water and alcohol). Additional mixing occurs. The slurry is coated onto a metal foil and allowed to dry.

[0095] The present disclosure further includes the following aspects.

[0096] Aspect 1: An electrode comprising: a current collector; and an active layer on the current collector, the active layer comprising electrode active particles, a conductive material, and a binder, the binder comprising a copolymer comprising first repeat units and second repeat units, wherein the first repeat units are derived from polymerization of a first monomer, the first monomer being an ethylenically unsaturated monomer having a hydrophilic pendant group, and the second repeat units are derived from polymerization of a second monomer having ethylenic unsaturation.

[0097] Embodiment 2: The electrode of embodiment 1, wherein the hydrophilic pendant group comprises a carboxylic acid group, a carboxylate salt group, an acetate group, an ester group, a nitrile group, a hydroxyl group, or an amide group.

[0098] Embodiment 3. The first repeat unit has the formula:

[0099] [ka] P is -LCOOR 1(In the formula, R 1 H, Na + , K. + , or Li + or a hydrocarbon group of 1 to 3 carbon atoms, preferably R 1 is H or a monovalent metal ion; -LC(O)N(R 2 )2(wherein, R 2 is independently in each occurrence H or an alkyl group of 1 to 3 carbon atoms, preferably 1 carbon atom; or -LOC(O)-R 3 (In the formula, R 3 is H or an alkyl group of 1 to 3, preferably 1, carbon atoms; LCN; or -LOH, wherein L, in each occurrence, is independently a direct bond or a hydrocarbon group of 1 to 3 carbon atoms, preferably L, in each occurrence, is a direct bond, and preferably P is -COOR 1 - where R 1 is a monovalent metal ion or H, R is independently in each occurrence H, an alkyl group of 1 to 3 carbon atoms, or one of the R's can be P as defined below, preferably R is H; The second repeat unit has the formula:

[0100] [ka] wherein R' is independently in each occurrence H; a hydrocarbon of 1 to 3 carbon atoms such as methyl; -LCOOR 4 (In the formula, R 4 is a hydrocarbon group of 1 to 3 carbon atoms; -LCN (wherein L in each occurrence is independently a direct bond or a hydrocarbon group of 1 to 3 carbon atoms, preferably L in each occurrence is a direct bond); or a 4-, 5-, or 6-membered lactam ring attached to the backbone of the repeat unit through a nitrogen atom, preferably wherein at least three of the R's are H and the fourth R' is a hydrocarbon group of 1 to 3 carbon atoms, such as methyl; -COOR 4 (In the formula, R 4is a hydrocarbon group of 1 to 3 carbon atoms); or a 4-, 5-, or 6-membered lactam ring attached to the backbone of the repeat unit through a nitrogen, with the proviso that R' is not identical to P in the A repeat unit.

[0101] Embodiment 4. The electrode of embodiment 3, wherein three R' are hydrogen and one has the following structure:

[0102] [ka]

[0103] Embodiment 5. The electrode of any one of Embodiments 1-4, wherein the pendant hydrophilic group comprises a carboxylic acid or a salt thereof.

[0104] Embodiment 6. The electrode of any one of embodiments 1 to 5, wherein the conductive elements form a network.

[0105] Embodiment 7. The electrode of any one of embodiments 1-6, wherein the conductive elements are high aspect ratio carbon elements.

[0106] Embodiment 8. The electrode of embodiment 7, wherein the high aspect ratio carbon elements comprise carbon nanotubes.

[0107] Embodiment 9. An energy storage device comprising the electrode of any one of embodiments 1-7.

[0108] Embodiment 10. The energy storage device of embodiment 9, wherein the energy storage device is a pouch cell device.

[0109] Embodiment 11. The energy storage device of embodiment 9 or 10, comprising a double-sided cathode disposed between two single-sided anodes, wherein at least one of the cathodes or anodes is an electrode according to any one of claims 1 to 6.

[0110] Embodiment 12: The energy storage device of any one of embodiments 9-11, comprising an electrolyte between two electrodes, e.g., a cathode and an anode.

[0111] Embodiment 13: The energy storage device of any one of embodiments 9-12, further comprising a permeable separator material between the electrodes, e.g., the cathode and the anode.

[0112] Embodiment 14: The energy storage device of any one of embodiments 9 to 13, comprising a housing.

[0113] Embodiment 15: The energy storage device of embodiment 14, further comprising one, and preferably two, terminals on the exterior of the housing to provide electrical connection to the electrodes.

[0114] Embodiment 16: A method of making an electrode according to any one of embodiments 1 to 8, comprising: providing a slurry comprising a conductive element, a binder, and an electrode active material in water, an alcohol, or a combination thereof; coating the slurry onto a current collector; and drying to remove the solvent.

[0115] All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with respect to each other (e.g., the range "up to 25% by weight, or more specifically, 5% to 20% by weight" includes the endpoints and all intermediate values ​​in the range "5% to 25% by weight", etc.). In addition, the stated upper and lower limits may be combined to form ranges (e.g., "at least 1 or at least 2% by weight" and "up to 10 or 5% by weight" may be combined as the ranges "1 to 10% by weight," or "1 to 5% by weight," or "2 to 10% by weight," or "2 to 5% by weight").

[0116] The present disclosure may alternatively comprise, consist of, or consist essentially of any suitable components disclosed herein. The disclosure may additionally or alternatively be formulated to be devoid of or substantially free of any component, material, compounding ingredient, adjuvant, or species used in prior art compositions or that is not otherwise necessary to achieve the function and / or purpose of the present disclosure.

[0117] All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in this application contradicts or conflicts with a term in an incorporated reference, the term from this application takes precedence over the conflicting term from the incorporated reference.

[0118] Unless otherwise stated herein, all test specifications are the latest specifications 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 specifications appear.

Claims

1. An electrode, A current collector; an active layer on the current collector, the active layer comprising electrode active particles, a conductive material, and a binder, the binder comprising a copolymer comprising first repeat units and second repeat units, the first repeat units derived from polymerization of a first monomer, the first monomer being an ethylenically unsaturated monomer having a hydrophilic pendant group, and the second repeat units derived from polymerization of a second monomer having ethylenic unsaturation.

2. 2. The electrode of claim 1, wherein the hydrophilic pendant group comprises a carboxylic acid group, a carboxylate salt group, an acetate group, an ester group, a nitrile group, a hydroxyl group, or an amide group.

3. The first repeat unit has the formula: 【Chemistry 1】 In the formula, P is -LCOOR １ (In the formula, R １ is H, a monovalent metal ion, or a hydrocarbon group of 1 to 3 carbon atoms; -LC(O)N(R ２ ) ２ (In the formula, R ２ is independently in each occurrence H or an alkyl group of 1 to 3 carbon atoms; -LOC(O)-R ３ (In the formula, R ３ is H or an alkyl group of 1 to 3 carbon atoms; -LCN; or -LOH, where L is independently in each occurrence a direct bond or a hydrocarbon group of 1 to 3 carbon atoms; R is independently in each occurrence H, an alkyl group of 1 to 3 carbon atoms, or one of the R's can be P; the second repeat unit has the formula: 【Chemistry 2】 wherein R' is independently in each occurrence H; a hydrocarbon of 1 to 3 carbon atoms; -LCOOR ４ (In the formula, R ４ -LCN, or a 4-, 5-, or 6-membered lactam ring attached to the backbone of the repeat unit through a nitrogen atom, where L is a direct bond or a hydrocarbon group of 1 to 3 carbon atoms, with the proviso that R' is not the same as P in the A repeat unit.

4. 4. The electrode of claim 3, wherein three R' are hydrogen and one has the following structure: 【Transformation 3】

5. The electrode of any one of claims 1 to 4, wherein the pendant hydrophilic group comprises a carboxylic acid or salt thereof.

6. 6. The electrode according to claim 1, wherein the conductive elements form a network.

7. 7. The electrode of claim 1, wherein the conductive elements are high aspect ratio carbon elements.

8. The electrode of claim 7 , wherein the high aspect ratio carbon elements comprise carbon nanotubes.

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

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

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