Binders for energy conversion and storage devices

Abstract

Described herein is an electrode active layer for an energy conversion or energy storage device, such as a supercapacitor or battery, comprising an active material and a binder comprising a salt of a sulfonated polymer. Also described herein are a slurry for producing such an active layer, a composite electrode comprising such an active layer, and the use of such an active layer in an energy conversion or energy storage device, as well as a method for fabricating such an active layer.

Description

[Technical Field]

[0001] The present invention relates to binders for use in energy conversion and energy storage devices. In particular, the present invention relates to polymeric materials containing ionically charged functional groups that function as binders. The binders herein can be used to provide improved performance in energy conversion and energy storage devices, such as supercapacitors, although the invention herein is not limited to that particular use. [Background technology]

[0002] Any discussion of prior art throughout this specification should not be taken as an admission that such prior art is well known or forms part of the common general knowledge in the art.

[0003] Energy conversion and storage devices are widely used in a variety of devices and applications. Capacitors are one such device, allowing for fast, high-power delivery of energy, but the amount of energy delivered is extremely low (i.e., they have low capacitance). Batteries are another, adept at storing even larger amounts of energy than capacitors, but compromise their design to allow for functionally sufficient power delivery. In between these devices, in terms of energy versus power, are supercapacitors, which generally allow for fast, high-power delivery of relatively large amounts of energy.

[0004] Supercapacitors (also known as ultracapacitors) can be generalized as either electric double-layer capacitors (EDLCs), pseudocapacitors, or hybrid capacitors. EDLCs store energy through electrostatic charge separation; pseudocapacitors (also known as electrochemical capacitors) store energy through a redox process but have the charge-discharge characteristics of capacitors; and hybrid capacitors store energy as a mixture of redox and electrostatic charge. Like batteries, supercapacitors generally contain two opposing electrodes electrically isolated by an intermediate, electrically insulating separator that is porous and permeated with an electrolyte. Two current collecting terminals typically connect to and extend from each electrode, allowing external access to the electrodes, and the entire unit is sealed in a package to prevent water and air ingress and electrolyte release.

[0005] Capacitance, or the ability to store an electric charge, is proportional to the overlap area of ​​charged plates and inversely proportional to the distance between the plates. Therefore, the performance of capacitors using conventional materials is limited by their size. To overcome this challenge, the present applicant has disclosed supercapacitor devices that overcome size issues by using ultra-high surface area carbon as the plate coating material; see WO 98 / 054739, WO 99 / 053510, WO 00 / 016352, WO 00 / 034964, WO 01 / 004920, WO 01 / 089058, and WO 12 / 151618, the contents of each of which are incorporated herein by reference. The electrodes are composed of metal current collectors, and the coating material is typically formed from particulate carbon and a binder used to adhere the carbon to itself and to the corresponding current collector. The coated electrodes are separated by separators, stacked or wound together, and placed within a housing containing the electrolyte.

[0006] The power performance of a supercapacitor is strongly affected by the internal resistance or equivalent series resistance (ESR) of the device, and a lower ESR of the device results in better power performance. ESR is the sum of the resistances of all materials, such as the current collector, active material, binder, separator, electrolyte, and all internal and external contact resistances.

[0007] As a component of the overall system, the binder used in supercapacitors has a strong influence on the ESR and, therefore, device performance. Binders are chemicals that provide the cohesive strength to hold the materials comprising the electrode active layer together, the adhesive strength to hold the electrode active layer to the current collector, and the means for electrical connection for charging and discharging the electrode. An ideal binder should interfere as little as possible with the functionality of the materials in the electrode active layer while still providing the necessary cohesive and adhesive functions. The binder also needs to be flexible so that the electrode active layer is not adversely affected by mechanical stresses, such as bending or vibration, that the device may experience over its operational lifetime. Typical binders used in the field include carboxymethyl cellulose (CMC), styrene butadiene (SBR), polytetrafluoroethylene (PTFE), poly(vinylidene fluoride) (PVDF), poly(tetrafluoroethylene), polyvinyl fluoride, ethylene-propylene-diene copolymer, and styrene-butadiene rubber, or copolymers and / or variants thereof. Many of the binders used in supercapacitors are also used as binders in battery electrodes.

[0008] The binder is generally mixed with the materials that make up the electrode active layer in a liquid carrier, such as water or an organic solvent, and the resulting slurry or suspension is then coated onto a substrate and dried to evaporate the liquid carrier.

[0009] Due to environmental concerns, there is a significant demand for binders that are compatible with aqueous coating processes. While CMC, polyacrylic acid (PAA), and polyvinyl alcohol (PVA) are each compatible with aqueous processes, they suffer from the drawbacks of containing reactive hydroxyl groups that reduce stability and result in gas generation, containing impurities such as chlorides, and / or having poor dispersion quality. Other water-dispersible binders in the form of latex particles, such as SBR, PTFE, and PVDF, require dispersants to stabilize the latex particles, which can reduce device performance and often necessitate the addition of adhesion promoters. These challenges for binders in supercapacitors also apply to battery energy storage applications.

[0010] As the field of energy conversion and storage devices evolves and applications become more demanding, there is a continuing need for new components, such as binders, that exhibit better stability and operational characteristics, such as improved ESR performance, and / or are compatible with environmentally friendly processing methods. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] International Publication No. 98 / 054739 [Patent Document 2] International Publication No. 99 / 053510 [Patent Document 3] International Publication No. 00 / 016352 [Patent Document 4] International Publication No. 00 / 034964 [Patent Document 5] International Publication No. 01 / 004920 [Patent Document 6] International Publication No. 01 / 089058 [Patent Document 7] International Publication No. 12 / 151618 [Non-patent literature]

[0012] [Non-Patent Document 1] Khomein et al., “Sulfonated aromatic polymer as a future proton exchange membrane: A review of sulfonation and crosslinking methods,” Renewable and Sustainable Energy Reviews, 2021, 137 Summary of the Invention [Problem to be solved by the invention]

[0013] It is an object of the present invention to at least overcome or ameliorate one or more of the disadvantages of the prior art, or to provide a useful alternative. [Means for solving the problem]

[0014] According to a first aspect of the present invention, there is provided an electrode active layer for an energy conversion or energy storage device, comprising an active material and a binder comprising a salt of a sulfonated polymer.

[0015] The following features may be used according to the first aspect above, either alone or in any suitable combination.

[0016] The sulfonated polymer may comprise a substituted C2-C6 linear or branched alkene monomer. The substituted C2-C6 linear or branched alkene monomer may have, as a substituent, -R1SO3 - , -R1ArSO3 - , -ArR1SO3 - , -ArSO3 - , or -C(=O)NHR1SO3 - , -C(=O)NHR1ArSO3 - , -C(=O)NHArR1SO3 -(wherein R1=C1-C6 linear or branched alkyl group or bond; and Ar=aryl group). Ar may be a phenyl group. The sulfonated polymer may contain benzenesulfonate groups.

[0017] The sulfonated polymer may comprise a monomer containing one sulfonate group per monomer. In some embodiments, the sulfonated polymer comprises a monomer containing one benzenesulfonate group per monomer. The sulfonated polymer may comprise one or more monomers selected from styrene sulfonate, vinyl sulfonate, 2-acrylamido-2-methyl-1-propanesulfonate, 2-propene-1-sulfonate, or 2-methyl-2-propene-1-sulfonate. In one embodiment, the monomer is styrene sulfonate.

[0018] The salts of the sulfonated polymers may include one or more counterions selected from Group I metal cations, Group II metal cations, transition metal cations, quaternary ammonium cations, or nitrogen-containing heterocyclic cations. The salts of the sulfonated polymers may include one or more counterions selected from lithium cations, potassium cations, sodium cations, cesium cations, magnesium cations, and calcium cations.

[0019] The salts of sulfonated polymers may include one or more counterions selected from optionally substituted alkylammonium cations, such as tetramethylammonium, tetraethylammonium, tetrapropylammonium, or tetrabutylammonium, or 2-(methylthio)ethylammonium cations, or nitrogen-containing heterocyclic cations, such as spiro-bis-pyrrolidinium (SBP), N,N-dimethylpyrrolidinium, N-methyl-N'-propylpyrrolidinium, N,N'-dimethylimidazolium, N-methyl-N'-ethylimidazolium, or N-methyl-N'-propylimidazolium.

[0020] The sulfonated polymer can have an average molecular weight of about 20,000 g / mol to about 2,000,000 g / mol. In one embodiment, the sulfonated polymer has an average molecular weight of about 20,000 g / mol to about 1,000,000 g / mol. In one embodiment, the sulfonated copolymer has an average molecular weight of about 20,000 g / mol to about 2,000,000 g / mol.

[0021] The binder may comprise at least 30% by weight of the salt of a sulfonated polymer. In one embodiment, the binder comprises at least 50% by weight of the salt of a sulfonated polymer. In one embodiment, the binder comprises at least 90% by weight of the salt of a sulfonated polymer.

[0022] The sulfonate polymer may be a copolymer comprising two or more different sulfonated monomers, or may be a copolymer comprising one or more sulfonated monomers and at least one other monomer, wherein the sulfonated monomers contain one sulfonate group per monomer, optionally one benzenesulfonate group per monomer, and the at least one other monomer has no sulfonate groups, and optionally the at least one other monomer is selected from one or more of 1,2-difluoroethylene, tetrafluoroethylene, styrene, butadiene, maleic anhydride, maleic acid or a salt thereof, acrylic acid or a salt thereof, methacrylic acid or a salt thereof, or butylacrylic acid or a salt thereof.

[0023] The binder may comprise a mixture of two or more different salts of a sulfonated polymer, or a mixture of a salt of a sulfonated polymer and at least one other polymer. The other polymer may be selected from PVDF, PTFE, SBR, or an acrylic polymer. The active material may be amorphous carbon, such as activated carbon.

[0024] The electrode active layer may further comprise a conductive material, for example conductive carbon.

[0025] According to a second aspect of the present invention, there is provided a composite electrode comprising an electrode active layer according to the first aspect above on a conductive surface.

[0026] According to a third aspect of the present invention, there is provided an energy storage device comprising the composite electrode according to the second aspect above. The energy storage device may be a supercapacitor or a battery. Accordingly, there is provided herein a supercapacitor comprising the composite electrode according to the second aspect above. There is also provided herein a battery comprising the composite electrode according to the second aspect above.

[0027] According to a fourth aspect of the present invention, there is provided the use of a salt of a sulfonated polymer as a binder in an electrode active layer of a composite electrode.

[0028] According to a fifth aspect of the present invention, there is provided an electrode slurry for producing an electrode active layer, the electrode slurry comprising an active material, a binder containing a salt of a sulfonated polymer, and a solvent.

[0029] The following features may be used in accordance with the fifth aspect above, either alone or in any suitable combination.

[0030] The electrode slurry may contain 50 wt% to 95 wt% of a solvent. The solvent may be water. The electrode slurry may contain 1 wt% to 30 wt%, for example 2 wt% to 20 wt%, of a binder on a solids basis. The slurry may be a substantially uniform dispersion of the active material.

[0031] According to a sixth aspect of the present invention, there is provided a method for fabricating an electrode active layer, the method comprising the steps of applying the electrode slurry according to the fifth aspect above to a current collector, and drying the electrode slurry to remove the solvent.

[0032] Unless the context clearly requires otherwise, throughout the description and claims, the words "comprises," "including," and the like are to be construed in an inclusive sense, i.e., "including, but not limited to," as opposed to an exclusive or exhaustive sense.

[0033] It should be understood that any numerical range recited herein is intended to include all subranges subsumed therein. For example, a range "from x to y" or "between x and y" is intended to include all subranges between x and y, and to extend to the endpoints x and y.

[0034] As used herein, the singular forms "a," "an," and "the" may refer to plural unless otherwise indicated.

[0035] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0036] [Figure 1] FIG. 1 shows the percent increase in ESR versus time for a supercapacitor containing an electrode with a sodium polystyrene sulfonate polymer (MW=100000 g / mol) binder according to one embodiment of the present invention compared to the percent increase in ESR for an equivalent supercapacitor containing a conventional CMC binder. [Figure 2] FIG. 2 shows the capacitance increase rate versus time for the same supercapacitor as in FIG. 1. [Figure 3] FIG. 2 shows the capacitance frequency response (Bode magnitude plot) of the same supercapacitor as in FIG. 1. [Figure 4] FIG. 2 shows a Bode phase plot of the same supercapacitor as in FIG. 1. [Figure 5] FIG. 2 shows the internal pressure of the same supercapacitor as in FIG. 1. [Figure 6] FIG. 2 shows the ESR increase rate versus time for a supercapacitor containing an electrode with a polystyrene sodium sulfonate polymer (MW=70000 g / mol) binder according to one embodiment of the present invention compared to the ESR increase rate of the PSS supercapacitor in FIG. 1 . [Figure 7] FIG. 7 shows the capacitance increase rate versus time for the same supercapacitor as in FIG. 6. [Figure 8] FIG. 1 shows the percentage increase in ESR versus time for supercapacitors containing electrodes comprising polystyrene sulfonate polymer (MW=75000 g / mol) binder with either Ca or Mg counterions, according to certain embodiments of the present invention. [Figure 9] FIG. 9 shows the capacitance increase rate versus time for the same supercapacitor as in FIG. 8. [Figure 10] FIG. 1 shows the percentage increase in ESR versus time for supercapacitors containing electrodes comprising polystyrene sulfonate polymer (MW=75000 g / mol) binder with either Li, K, or Cs counterions, according to certain embodiments of the present invention. [Figure 11] FIG. 11 shows the capacitance increase rate versus time for the same supercapacitor as in FIG. 10. [Figure 12] FIG. 1 shows the capacitance growth rate versus time for an asymmetric supercapacitor containing an electrode with a polystyrene sulfonate polymer binder according to one embodiment of the present invention and an electrode containing a conventional binder SBR. [Figure 13] FIG. 13 shows the rate of increase in ESR versus time for the same supercapacitor as in FIG. 12. [Figure 14] FIG. 13 shows the EIS Nyquist plot of the same supercapacitor as in FIG. 12. [Figure 15] FIG. 13 shows the Bode phase plot for the same supercapacitor as in FIG. 12. [Figure 16]FIG. 13 shows an EIS resistance Bode plot of the same supercapacitor as in FIG. 12. [Figure 17] FIG. 13 shows an EIS capacitance Bode plot of the same supercapacitor as in FIG. 12. [Figure 18] FIG. 1 shows the percentage increase in ESR versus time for a supercapacitor containing an electrode with a polystyrene sulfonic acid-maleic acid copolymer (MW=20000 g / mol) binder according to certain embodiments of the present invention. [Figure 19] FIG. 19 shows the capacitance increase rate versus time for the same supercapacitor as in FIG. 18. DETAILED DESCRIPTION OF THE INVENTION

[0037] The invention described herein relates to binders comprising polymeric materials containing sulfonate functional groups for use in electrode active layers as components of energy conversion and energy storage devices. More specifically, the disclosure herein encompasses electrode active layers for energy conversion or energy storage devices comprising an active material and a binder comprising a salt of a sulfonated polymer.

[0038] The inventors have found that sulfonated polymer salts are particularly useful as binders in electrode active layers. Furthermore, when used as binders, the ESR increase in otherwise equivalent devices is significantly lower with sulfonated polymer salts than with the standard binder CMC. Surprisingly, the inventors have also found that sulfonated polymer salts have comparable active material dispersion properties in aqueous systems compared to CMC. Dispersion properties are an important characteristic of binders, as conventional methods generally involve applying a slurry containing a binder, solvent, and active material to a conductive surface. Therefore, any non-uniformity and aggregation / agglomeration of particles in the slurry may be reflected in the deposited electrode active layer. In electrode slurries containing a mixture of particles, such as active material and conductive material, even dispersion and dispersion of the materials in the slurry can optimize electrode / electrolyte contact and conductivity through the dry electrode active layer, thereby providing performance benefits for energy conversion / energy storage devices. Without wishing to be bound by any particular theory, the superior dispersion quality of the binders described herein significantly improves the life performance of supercapacitors utilizing such binders compared to supercapacitors using CMC as the binder, as measured by both the rate of ESR increase and capacity loss over time, and improved frequency response. Furthermore, the chemical composition of the binders herein advantageously avoids chemical side reactions during charge-discharge cycling, provides good adhesion to the current collector, and / or provides good cohesion between the binder and the active material.

[0039] In some embodiments, the salts of the sulfonated polymers described herein are soluble in water, thereby allowing for the manufacture of electrode active layers using more environmentally friendly aqueous processing.

[0040] Finally, when used as binders, the sulfonated polymer salts described herein advantageously reduce gas buildup during use compared to conventional CMC binders. Gas buildup can lead to premature equipment failure. Further advantages of the binders described herein will become apparent in the following description.

[0041] While certain sulfonated polymers are known for their ionic properties and have therefore been used to date in charge transfer or thin film applications, the present inventors have for the first time discovered the utility of sulfonated polymers as binders, particularly in composite electrodes useful in energy conversion and energy storage devices. The unexpected properties of the salts of the sulfonated polymers of this particular application, in the form of better dispersion characteristics in aqueous electrode active material mixtures and advantageous effects with respect to lower ESR and reduced gas generation compared to standard binders in the art, have not previously been fully appreciated.

[0042] For the following discussion, the term "supercapacitor" refers to devices also known as ultracapacitors, electrochemical double layer capacitors (EDLCs), and electrochemical capacitors, pseudocapacitors, and hybrid supercapacitors, among others. All such devices are considered devices within the scope of this disclosure. Furthermore, while the invention described herein is primarily developed for supercapacitors and will be described with reference to that application, it will be understood that the binders described herein may also be suitable for other energy storage devices, such as batteries. All such devices are considered energy conversion or energy storage devices for the purposes of this disclosure.

[0043] As used herein, the term "electrode active layer" refers to a layer containing materials active in the storage and / or conversion of chemical and / or electrical energy. The electrode active layer comprises at least one active material and a binder. The conductive surface acting as a current collector forms part of the overall composite electrode, of which the electrode active layer is a part.

[0044] As used herein, the term "substantially" refers to within + / - 5%, within + / - 4%, within + / - 3%, within + / - 2%, or within + / - 1%.

[0045] [Electrode active layer] Described herein is an electrode active layer for an energy conversion or energy storage device comprising an active material and a binder comprising a salt of a sulfonated polymer. The sulfonate group has the formula -SO3 - and has the following structure as a functional group, in which R is an organic group.

[0046] [ka]

[0047] As used herein, the term "sulfonate" refers to a sulfonate anion functional group, which is the deprotonated form of sulfonic acid. Any reference to sulfonate herein implicitly refers to a sulfonate salt (as opposed to an ester), with the salt being understood to be distinguished by the inclusion of a non-hydrogen cation that is a counterion to the negative charge carried by the sulfonate anion. A sulfonated polymer is one that contains a sulfonate functional group. For the avoidance of doubt, sulfonic acid polymers in their acid form are outside the scope of the term sulfonate salt.

[0048] In one embodiment, the binder herein includes a partially fluorinated sulfonate polymer, which refers to a sulfonate polymer in which all hydrogens bonded to carbons of the organic polymer have been replaced with fluorine. In such cases, it can be understood that fluorination of some, but not all, of the organic carbons of the polymer is acceptable. In another embodiment, the binder herein may include a non-fluorinated sulfonate polymer. "Non-fluorinated" means that the sulfonate polymer does not contain any fluorine atoms. In one embodiment, the binder herein, whether sulfonated or not, is free of perfluorinated polymers and perfluorinated monomers. In one embodiment, the binder herein, whether sulfonated or not, is free of fluorinated polymers and fluorinated monomers.

[0049] In some embodiments, the binder herein comprises a non-chemically crosslinked sulfonate polymer. "Non-chemically crosslinked" means that the polymer does not contain chemical, i.e., covalent, crosslinking bonds, and no chemical, i.e., covalent, crosslinking agents are used.

[0050] It will be understood that cations, such as metal cations, can have a physical (e.g., ionic) cross-linking effect in negatively charged polymers. This type of physical cross-linking is permitted in polymers, including binders, herein.

[0051] The sulfonated polymer can have any suitable structure. In one embodiment, the sulfonated polymer is derived from at least some monomers that contain sulfonate groups. In other embodiments, the polymer is post-synthetically modified to contain sulfonate groups, for example, by reacting other functional groups on the polymer to form sulfonate groups. Those skilled in the art will be familiar with methods for producing various sulfonate polymers, for example, as described in Khomein et al., "Sulfonated aromatic polymers as a future proton exchange membrane: A review of sulfonation and crosslinking methods," Renewable and Sustainable Energy Reviews, 2021, 137, the contents of which are incorporated herein by cross-reference, or can utilize commercially available sulfonate polymers, such as poly(4-styrenesulfonic acid) solution, 2-propene-1-sulfonic acid (allylsulfonic acid), or 2-acrylamido-2-methyl-1-propanesulfonic acid, each of which can be reacted with a base to form its salt, such as a hydroxide or carbonate, or poly(sodium 4-styrenesulfonate), vinylsulfonic acid, sodium salt, or 2-methyl-2-propene-1-sulfonic acid sodium salt, all of which can be obtained from Sigma-Aldrich.

[0052] In one embodiment, the sulfonated polymer is derived from a monomer containing one sulfonate group per monomer. In one embodiment, the sulfonated polymer is derived from a monomer containing a substituted C2-C6 linear or branched alkene. The alkene preferably contains one vinyl (C=C) group. In one embodiment, the substituted C2-C6 linear or branched alkene is a C2 alkene (C=C), a C3 alkene (C=CC), a C4 alkene (C=CCC), (CC=CC), (C=C(C)-C), etc., a C5 alkene, or a C6 alkene (hydrogen and substituents not shown). Substitution may occur on any carbon in the C2-C6 linear or branched alkene.

[0053] The C2-C6 linear or branched alkene may include any suitable substituent, but in one embodiment, the substituent is -R1SO3 - , -R1ArSO3 - , -C(=O)NHR1SO3 - , -C(=O)NHR1ArSO3 - , -C(=O)NHArR1SO3 - , -ArR1SO3 - , or -ArSO3 - wherein R1=C1-C6 linear or branched alkyl group or a bond and Ar=aryl group. In one embodiment, the aryl group is a phenyl group.

[0054] In one embodiment, the monomer is H2C=CH-R1SO3 - , H2C=CH-R1ArSO3 - , H2C=CH-ArR1SO3 - , or H2C=CH-ArSO3 - where R1=C1-C6 linear or branched alkyl group or a bond and Ar=aryl group. In one embodiment, the monomer is (C3H5)-R1SO3 - , (C3H5)-R1ArSO3 - , (C3H5)-ArR1SO3 - , or (C3H5)-ArSO3 -where R1=C1-C6 linear or branched alkyl group or a bond and Ar=aryl group. In another embodiment, the monomer is H2C=CH-CH2-R1SO3 - , H2C=CH-CH2-R1ArSO3 - , H2C=CH-CH2-ArR1SO3 - , or H2C=CH-CH2-ArSO3 - where R1=C1-C6 linear or branched alkyl group or a bond and Ar=aryl group. In one embodiment, the monomer is (C4H7)-R1SO3 - , (C4H7)-R1ArSO3 - , (C4H7)-ArR1SO3 - , or (C4H7)-ArSO3 - (wherein R1=C1 to C6 linear or branched alkyl group or a bond and Ar=aryl group).

[0055] In another embodiment, the monomer is H2C=CH-CH2-R1SO3 - , H2C=CH-CH2-R1ArSO3 - , H2C=CH-CH2-ArR1SO3 - , or H2C=CH-CH2-ArSO3 - where R1=C1-C4 linear or branched alkyl group or a bond and Ar=phenyl group. In another embodiment, the monomer is H2C=CH-R1SO3 - , H2C=CH-R1ArSO3 - , H2C=CH-ArR1SO3 - , or H2C=CH-ArSO3 - where R1=C1 or C2 linear alkyl group or a bond and Ar=phenyl group.

[0056] In a further embodiment, the monomer is —C(═O)NHR1SO3 - , -C(=O)NHR1ArSO3 - , or -C(=O)NHArR1SO3 -where R1=C1-C6 linear or branched alkyl group or a bond and Ar=phenyl group. In a further embodiment, the monomer is -C(=O)NHR1SO3 - (In the formula, R1=C 3~5 branched alkyl group and Ar=phenyl group, or where R1=-C(CH3)2CH2- and Ar=phenyl group).

[0057] In one embodiment, the sulfonate-bearing groups in the polymer are benzenesulfonate groups, for example, as shown below.

[0058] [ka]

[0059] In one embodiment, the sulfonated polymer is derived from monomers containing one benzenesulfonate group per monomer, hi one embodiment, the sulfonated groups in the polymer comprise benzenesulfonate groups.

[0060] In one embodiment, the binder comprises a salt of poly(styrene sulfonate), poly(vinyl sulfonate), poly(2-acrylamido-2-methyl-1-propanesulfonate), poly(2-propene-1-sulfonate), or poly(2-methyl-2-propene-1-sulfonate). In one embodiment, the binder is comprised of a salt of poly(styrene sulfonate), poly(vinyl sulfonate), poly(2-acrylamido-2-methyl-1-propanesulfonate), poly(2-propene-1-sulfonate), or poly(2-methyl-2-propene-1-sulfonate). In one embodiment, the binder comprises a salt of poly(styrene sulfonate). In one embodiment, the binder comprises a salt of poly(2-acrylamido-2-methyl-1-propanesulfonate). In one embodiment, the binder comprises a salt of poly(2-propene-1-sulfonate). In one embodiment, the binder comprises a salt of poly(2-methyl-2-propene-1-sulfonate). In one embodiment, the binder does not comprise a salt of poly(vinyl sulfonate).

[0061] The salt of the sulfonated polymer may include any suitable cation. In one embodiment, the polymer includes a Group I metal cation, a Group II metal cation, a transition metal cation, or an ammonium-based cation as a counterion. The salt of the sulfonated polymer may include one or more counterions selected from Group I metal cations or Group II metal cations. This embodiment may be preferred when water solubility for processing is highly desirable. Such cations include lithium cations, potassium cations, sodium cations, cesium cations, magnesium cations, and calcium cations. In one embodiment, the salt of the sulfonated polymer may include a Group I metal cation. In one embodiment, the salt of the sulfonated polymer may include a Group II metal cation. In some embodiments, the salt of the sulfonated polymer includes sodium cations, lithium cations, magnesium cations, or calcium cations, such as sodium salts, lithium salts, magnesium salts, or calcium salts. In some embodiments, mixtures of various cations, such as a mixture of Li cations and Na cations or a mixture of Ca cations and Mg cations, may be used as counterions for the same polymer chain. Other cation combinations will be apparent to those skilled in the art. In other embodiments, the salt of the sulfonated polymer may include one or more transition metal cations, such as zinc cations, iron cations, and / or nickel cations. In one embodiment, the binder is comprised of one salt of the sulfonated polymer. In another embodiment, the binder comprises a mixture of two or more different salts of the sulfonated polymer.

[0062] In some embodiments, cations can be selected to match the ionic system of an energy storage and / or energy conversion device. Ionic uniformity between the electrochemically active materials in the device and binder can suppress competing redox reactions. By way of non-limiting example only, a hybrid Li-ion / supercapacitor device may include a lithium salt of a sulfonated polymer, and a hybrid K-ion / supercapacitor device may include a potassium salt of a sulfonated polymer. Other energy storage and energy conversion devices utilizing elements such as sodium, zinc, iron, or nickel can utilize sodium, zinc, iron, or nickel salts of a sulfonated polymer.

[0063] In one embodiment, the salt of the sulfonated polymer may include an ammonium-based cation. Such cations are often used as cationic components in EDLCs and include, but are not limited to, primary alkylammonium cations, secondary alkylammonium cations, tertiary alkylammonium cations, or quaternary alkylammonium cations, and their substituted equivalents, such as 2-(methylthio)ethylammonium cations. Quaternary ammonium cations are known to be particularly stable at typical operating voltages of supercapacitors. Quaternary ammonium cations are the most commonly used cations in EDLC electrolytes and are suitable for use as the cation of the salt in the binder described herein. Suitable quaternary ammonium cations include, but are not limited to, tetramethylammonium cation, methyltriethylammonium cation, tetraethylammonium cation, tetrapropylammonium cation, or tetrabutylammonium cation. In one embodiment, the quaternary ammonium cation has the following chemical structure: [ka] In the formula, R 1 , R 2 , R 3 , and R 4Each is an alkyl substituent. 1 , R 2 , R 3 , and R 4 are each independently a C1 to C7 linear or branched alkyl chain. 1 , R 2 , R 3 , and R 4 is independently a C1 to C4 linear or branched alkyl chain. 1 , R 2 , R 3 , and R 4 is independently a C1-C2 linear alkyl chain. 1 is R 2 , R 3 , and R 4 In one embodiment, R 1 , R 2 , R 3 , and R 4 are different from each other.

[0064] In another embodiment, the salt of the sulfonated polymer may include a nitrogen-containing heterocyclic cation. Suitable examples are spiro-bis-pyrrolidinium (SBP), N,N-dimethylpyrrolidinium, N-methyl-N'-propylpyrrolidinium, N,N'-dimethylimidazolium, N-methyl-N'-ethylimidazolium, and N-methyl-N'-propylimidazolium. In one embodiment, the quaternary ammonium cation is a nitrogen-containing heterocyclic cation having the following chemical structure: [ka] In the formula, R 5 and R 6 Each is an alkyl substituent. 5 and R 6 each independently comprises a C1 to C7 linear or branched alkyl chain. 5 is R 6 is different from.

[0065] The sulfonated polymers described herein can have any suitable average molecular weight, referring to the average molecular weight of each polymer chain. In one embodiment, the average molecular weight of the polymer is from about 20,000 g / mol to about 2,000,000 g / mol, or from 20,000 to 100,000 g / mol, or from 70,000 g / mol to 125,000 g / mol, or from 85,000 g / mol to 140,000 g / mol, or from 100,000 g / mol to 500,000 g / mol, or from 250,000 g / mol to 750,000 g / mol, or from 500,000 g / mol to 1,000,000 g / mol, or from 1,000,000 g / mol to 1,500,000 g / mol, or from 1,250,000 g / mol to 2,000,000 g / mol, or from 700,000 g / mol to 2,000,000 g / mol. 0,000 g / mol to 1,250,000 g / mol, or 50,000 g / mol, 60,000 g / mol, 70,000 g / mol, 75,000 g / mol, 80,000 g / mol, 90,000 g / mol, 100,000 g / mol, 110,000 g / mol, 120,000 g / mol, 130,000 g / mol, 140,000 g / mol, 150,000 g / mol, 250,000 g / mol, 500,000 g / mol, 1,000,000 g / mol, 1,250,000 g / mol, 1,500,000 g / mol, 1,750,000 g / mol, or 2,000,000 g / mol. This molecular weight may be the molecular weight of the protonated form of the polymer before the polymer is converted to a salt.Alternatively, in other embodiments, the average molecular weight of the polymeric salt is from about 50,000 g / mol to about 2,000,000 g / mol, or from 50,000 to 10,000 g / mol, or from 70,000 g / mol to 125,000 g / mol, or from 85,000 g / mol to 140,000 g / mol, or from 100,000 g / mol to 500,000 g / mol, or from 250,000 g / mol to 750,000 g / mol, or from 500,000 g / mol to 1,000,000 g / mol, or from 1,000,000 g / mol to 1,500,000 g / mol, or from 1,250,000 g / mol to 2,000,000 g / mol, or is 70,000 g / mol to 1,250,000 g / mol, or 50,000 g / mol, 60,000 g / mol, 70,000 g / mol, 75,000 g / mol, 80,000 g / mol, 90,000 g / mol, 100,000 g / mol, 110,000 g / mol, 120,000 g / mol, 130,000 g / mol, 140,000 g / mol, 150,000 g / mol, 250,000 g / mol, 500,000 g / mol, 1,000,000 g / mol, 1,250,000 g / mol, 1,500,000 g / mol, 1,750,000 g / mol, or 2,000,000 g / mol. In such embodiments, the molecular weight includes the counterion of the salt when the polymer is converted to a salt. In one embodiment, the molecular weight of the polymer is about 70,000 g / mol to about 100,000 g / mol. In one embodiment, the molecular weight of the polymer salt is about 70,000 g / mol to about 100,000 g / mol. In one embodiment, the molecular weight of the polymer salt is about 100,000 g / mol to about 1,000,000 g / mol. In one embodiment, the molecular weight of the polymer salt is about 70,000 g / mol to about 900,000 g / mol.

[0066] The binder may comprise any suitable wt % of the salt of the sulfonated polymer, hi some embodiments, the binder is a pure salt of the sulfonated polymer, such that the binder comprises about 100 wt %, or at least 99%, at least 98%, at least 95%, or at least 90% of the salt of the sulfonated polymer.

[0067] In another embodiment, the binder comprises a copolymer derived from two or more different sulfonated monomers, or one or more sulfonated monomers and at least one other monomer. The nature of the copolymer is not particularly limited, although random copolymers may be preferred over block copolymers.

[0068] When the copolymer includes two or more different sulfonated monomers, each monomer may be as described above, or other sulfonated monomers may be utilized, such as 2-acrylamido-2-methyl-1-propanesulfonate (PAMP).

[0069] When the copolymer includes at least one other monomer, the at least one other monomer may or may not be sulfonated. The at least one other monomer may not be fluorinated. The at least one other monomer may not be perfluorinated. In one embodiment, the at least one other monomer includes an optionally substituted C2-C6 cyclic linear or branched alkene, such as a C2 alkene (C═C), a C3 alkene (C═CC), a C4 alkene (C═CCC), (CC═CC), (C═C(C)-C), a C5 alkene, or a C6 alkene (hydrogen and substituents not shown). The optional substituent may be a phenyl group, a C1-C6 linear or branched alkyl group, a carboxylic acid, a carbonyl, or an amide. In one embodiment, the at least one other monomer is a substituted alkene, such as 1,2-difluoroethylene, tetrafluoroethylene, or maleic acid or a salt thereof. In one embodiment, the at least one other monomer is styrene and butadiene. In one embodiment, the at least one other monomer is an acrylic monomer, such as acrylic acid or a salt thereof, methacrylic acid or a salt thereof, or butylacrylic acid or a salt thereof. In one embodiment, the C2-C6 linear or branched alkene is unsubstituted. In one embodiment, the at least one other monomer is a cyclic anhydride having a C=C bond, such as maleic anhydride. In one embodiment, the sulfonated monomer contains one sulfonate group per monomer, optionally one benzenesulfonate group per monomer, and the at least one other monomer has no sulfonate groups.

[0070] In one embodiment, when the binder comprises two or more different sulfonated monomers, or a copolymer derived from one or more sulfonated monomers and at least one other monomer, the copolymer comprises 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% sulfonated monomer, or 30-99 wt%, or 30-50 wt%, or 50-75 wt%, or 70-90 wt%, or 60-99 wt% sulfonated monomer, or 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt%, 95 wt%, 9 ... 0 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt%, 95 wt%, or 99 wt% of sulfonated monomers, at least 30 mol%, at least 40 mol%, at least 50 mol%, at least 60 mol%, at least 70 mol%, at least 80 mol%, at least 90 mol%, at least 95 mol%, or at least 99 mol% of sulfonated monomers, or 30 to 99 mol%, or 30 to 50 mol%, or 50 to 75 mol%, or 70 to 90 mol%, or 60 to 99 mol% of sulfonated monomers, or 30 mol%, 40 mol%, 50 mol%, 60 mol%, 70 mol%, 80 mol%, 90 mol%, 95 mol%, or 99 mol% of sulfonated monomers.

[0071] In one embodiment, the binder comprises a mixture of a salt of a sulfonated polymer and at least one other polymer, such as a polymer made from at least one other monomer as described above. In one embodiment, the at least one other polymer may be PVDF, PTFE, SBR, or an acrylic polymer. In such an embodiment, the mixture may comprise 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 sulfonated polymer or salt thereof, or 30-99 wt%, or 30-50 wt%, or 50-75 wt%, or 70-90 wt%, or 60-99 wt% of the sulfonated polymer or salt thereof. In one embodiment, the binder herein comprises a salt of a sulfonated polymer in a mixture or blend with conventional compounds used as binders in energy storage devices. Suitable conventional compounds for use in mixtures or blends with the salts of the sulfonated polymers described herein include, but are not limited to, PVDF, PTFE, SBR, or acrylic binders.

[0072] In one embodiment, the binders herein are completely soluble in water or have a solubility of at least 0.02 g / mL in water. In one embodiment, the binders herein comprising sulfonated polymers are completely soluble in water or have a solubility of at least 0.1 g / mL in water.

[0073] In one embodiment, the binder herein has a pH of about 7, or 6-8, e.g., 6.5-7.5, or 6.8-7.2, or about 6, about 6.25, about 6.5, about 6.75, about 7.0, about 7.25, about 7.5, about 7.75, or about 8. In some embodiments, the pH of the binder can be adjusted using a base, such as a metal hydroxide, or an acid, such as tetrafluoroboric acid, TFSI acid, or methylsulfonic acid.

[0074] Electrode active layers for the energy conversion or energy storage devices described herein include active materials, including but not limited to cathode materials, anode materials, and electrochemically active materials, which may include solvents, additives, and / or electrolyte salts, depending on the application.

[0075] The active material in the electrode active layer described herein is not particularly limited. In one embodiment, the active material is carbon-based. In one embodiment, the active material is amorphous carbon, carbon nanotubes, graphene, graphene oxide, reduced graphene oxide, or activated carbon.

[0076] Activated carbon has a high surface area and porosity that makes it particularly suitable for use in EDLC supercapacitor devices; its high surface area and porous nature increases the effective area of ​​the capacitor plate and therefore the maximum achievable capacitance. Thus, in one embodiment, the active material is activated carbon. In one embodiment, the activated carbon has a surface area of ​​at least 1200 m 2 In another embodiment, the carbon-based material has a surface area of ​​at least 400 m 2 / g. In one embodiment, the activated carbon has a surface area of ​​1200 m 2 / g to 3000m 2 / g。 In another embodiment, the activated carbon has a particle size D50 between 3 μm and 10 μm, and D10 > 1 μm and D90 < 30 μm. In another embodiment, the activated carbon is a microporous carbon, with more than 50% of the pore volume less than 2 nm in size. Examples of commercially available microporous activated carbons suitable for use as the active material herein include MSP20 (Kansai Thermochemical Co., Ltd.), MSC-30 (Kansai Thermochemical Co., Ltd.), FAR01X (Kansai Thermochemical Co., Ltd.), YP-80F (Kuraray Co., Ltd.), RP-25 (Kuraray Co., Ltd.), RP-20 (Kuraray Co., Ltd.), NY1151 (Kuraray Chemical Co., Ltd.), NK261H (Kuraray Co., Ltd.), HDLC 20B STUW (Haycarb PLC), DLC 30 (Haycarb PLC), DLC 20P (Haycarb PLC), HCE-201 (Haycarb PLC), HCE-202 (Haycarb PLC), ACS20 (China Steel Chemical Corporation), ACS25 (China Steel Chemical Corporation), Yec-200E (IHUAN Carbon), YEC-8A (IHUAN Carbon Co., Ltd.), YEC-8B (IHUAN Carbon Co., Ltd.), Y-Carbon (Y-Carbon Inc.), ZL-302 (Huzhou Sensheng Activated Carbon Co., Ltd.), MCSP 2005 (Calgon Mitsubishi Chemical Corporation), MCSP 1805A (Calgon Mitsubishi Chemical Corporation), and MCSP 1805-1 (Calgon Mitsubishi Chemical Corporation).

[0077] In another embodiment, the activated carbon may be classified as a mesoporous carbon, in which more than 50% of the pore volume has a pore size greater than 2 nm. Examples of commercially available mesoporous carbons suitable for use as the active material herein are P2-15 (EnerG2), MSA-20 (Kansai Coke Chemicals), YP-50F (Kuraray Co., Ltd.), NY1251H (Kuraray Co., Ltd.), YPS (Kuraray Co., Ltd.), ACS15 (China Steel Chemical Corporation), TDA 60 (TDA Research), SO-15A (TDA Research), and ACC (Xiamen All Carbon Corporation).

[0078] In other embodiments, the active material may be oxide-based, such as a transition metal oxide. These oxide materials are often used as cathode active materials in batteries or supercapacitors, and sometimes as anodes. Examples of transition metal oxides can include NiO, ZnO, RuO, MnO, CoO, WO, VO, LiTiO, and mixed metal oxides such as XCoO (X = Mn, Cu, Ni) and AMoO (A = Co, Mn, Ni, Zn). Other cathode materials typically used in batteries, hybrid capacitors, or pseudocapacitors include layered oxides, oxoanions, polyanions, and Prussian blue and its analogs LiCoO2, LiMn2O4, LiFePO4, lithium nickel manganese cobalt oxide (NCM), commonly denoted as LiNiMnCoO2, lithium nickel cobalt aluminum oxide (NCA), commonly denoted as LiNiCoAlO2, lithium nickel cobalt manganese aluminum oxide (NCMA) LiNiCoMnAlO2, LiNiO2, NaFeMnO2, NaMnMgO2, NaNiMnMgO2, KMnO2, KCoO2, etc.

[0079] In one embodiment, a carbon-based anode battery-type material may be used as the active material. In another embodiment, the active material is graphite, hard carbon, or soft carbon. In one embodiment, the anode may be silicon-based.

[0080] In certain embodiments, the active material is a composite of a carbon-based and oxide-based system, such as graphene oxide or an activated carbon / metal oxide composite. Suitable commercial sources of active materials, such as activated carbon, are known to those skilled in the art.

[0081] The electrode active layer herein can have any suitable thickness. In one embodiment, the electrode active layer has a thickness of 5 μm to 200 μm, or 5 μm to 100 μm, 5 μm to 80 μm, 5 μm to 60 μm, or 5 μm to 50 μm when dried.

[0082] The binder can be present in any suitable amount in the electrode active layer. The amount of binder in the electrode active layer can be calculated as a weight percentage of the total solid components in the electrode active layer, excluding the electrolyte. In one embodiment, the binder is present in an amount of 1 to 30 wt% of the electrode active layer, or 1 to 10 wt%, or 5 to 20 wt%, or 10 to 25 wt%, or 15 to 30 wt%, or 2 to 20 wt% of the electrode active layer, or 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 12.5 wt%, 15 wt%, 17.5 wt%, 20 wt%, 25 wt%, or 30 wt% of the electrode active layer. Wt% is defined as [mass]. バインダー / (mass バインダー +mass 活物質 +mass 存在する場合、他の固形分 )]×100.

[0083] In one embodiment, the electrode active layer further comprises a conductive material. A conductive material is generally required when the active material has insufficient conductivity in an energy storage / energy conversion device or when it is desired to increase the conductivity within the electrode active layer. In some embodiments, the use of a carbon-based active material, such as activated carbon, may require the addition of a conductive material.

[0084] The nature of the conductive material is not particularly limited. In some embodiments, the conductive material is conductive carbon, such as carbon black, graphite, graphene, carbon nanotubes, etc. In one embodiment, the conductive material is conductive carbon or carbon black. In one embodiment, the carbon black has a viscosity of about 100 to 500 mPa. 2 / g BET(N2) surface area. In another embodiment, the carbon black has a submicron primary particle size between 10 nm and 100 nm. Carbon black particles often agglomerate, requiring high shear to adequately disperse them in the electrode slurry. Suitable commercially available sources of conductive materials, such as conductive carbon, are known to those skilled in the art and include Printex carbon black, e.g., L6 (Orion Carbons), PRINTEX® kappa 100 (Orion Engineered Carbons), PRINTEX® XE2 (Orion Engineered Carbons), ENSACO 150G (IMERYS), ENSACO 210G (IMERYS), ENSACO 250G (IMERYS), ENSACO 250F (IMERYS), ENSACO 260G (IMERYS), ENSACO 350G (IMERYS), Super C65 (IMERYS), LITX® HP (CABOT), LITX300 (CABOT), LITX200 (CABOT), VXC72R (CABOT), BP 700 (CABOT), BP 2000 (CABOT), SC2A (CABOT), TPX1278 (CABOT), Lump Black (Degussa), Ketjenblack EC300J (Akzo Noble), Ketjenblack EC600JD (Akzo Noble), E-MM-198G (Timcal), and Super P (Timcal).

[0085] [Composite electrode] Described herein is a composite electrode comprising an electrode active layer on a conductive surface, the electrode active layer comprising an active material and a binder comprising a salt of a sulfonated polymer.

[0086] Also described herein is the use of salts of sulfonated polymers described herein as binders in the electrode active layer of a composite electrode.

[0087] The electrode active layer in a composite electrode is in contact with the current collector and is generally produced in situ to maximize adhesion of the electrode active layer to the current collector. In such embodiments, the binder and active material are processed into an electrode slurry in a solvent, and the electrode slurry is applied to the current collector using any suitable application means. The solvent is then evaporated by a drying process, leaving the electrode active layer, including the binder and active material, on the current collector.

[0088] Suitable methods for making composite electrodes are described elsewhere herein. The current collector is not particularly limited and may generally comprise any conductive material, although in some embodiments, the current collector is a metal foil. Suitable metal foils may include aluminum foil or copper foil, although other metal foils may also be suitable.

[0089] [Device] An energy storage device including the composite electrode described above is also described herein. The energy storage device is not particularly limited, but in one embodiment, the energy storage device is a supercapacitor or a battery. In one embodiment, the energy storage device is a supercapacitor. The supercapacitor may be a prismatic supercapacitor or a cylindrical supercapacitor. In one embodiment, the energy storage device is a battery. In one embodiment, the battery is a Li-ion battery, a Na-ion battery, a K-ion battery, an Al-ion battery, or a Ca-ion battery. In one embodiment, the energy storage device is a supercapacitor-battery hybrid. In one embodiment, the hybrid device is a Li-ion / supercapacitor hybrid, a K-ion / supercapacitor hybrid, a Na-ion / supercapacitor hybrid, an Al-ion / supercapacitor hybrid, or a Ca-ion / supercapacitor hybrid.

[0090] The binders of the present invention can be used to fabricate either symmetric or asymmetric energy storage devices. In symmetric devices, each electrode utilizes the same binder. In asymmetric devices, the binder composition is varied so that the first and second electrodes have different binders. Asymmetric electrodes enable higher voltages and higher energy densities in supercapacitors. Higher voltage operation is possible by varying the energy density at each electrode to ensure that the voltage drop across the electrode interface is optimal for the electrode's energy access and energy stability. Batteries are inherently asymmetric devices because the chemistry of each electrode is optimized for oxidation or reduction. In such cases, the binder is selected to be stable in the electrochemical environment at each electrode.

[0091] Thus, in one embodiment, the energy storage device includes at least two composite electrodes, each of which includes the same binder. This embodiment is particularly suitable for supercapacitors.

[0092] In another embodiment, the energy storage device includes two composite electrodes, each of which includes a different binder. This embodiment is suitable for supercapacitors, batteries, and hybrid devices.

[0093] In the energy storage and energy conversion devices described herein, the free space between the electrodes generally contains an electrolyte, which is often a solvent containing dissolved salts. In supercapacitors, the electrolyte not only provides the ion source necessary to form a bilayer on the surface of the carbon-containing electrode active layer, but also enables ionic conductivity between the opposing electrodes. The electrolyte in the devices described herein is not particularly limited. Those skilled in the art are familiar with electrolytes suitable for use in energy storage and energy conversion devices, and are familiar with electrolytes suitable for use in the devices described herein. In one embodiment, the electrolyte comprises an ionic liquid, or an organic sulfur compound, such as sulfolane, an organic carbonate, such as propylene carbonate or gamma-butyrolactone, and at least one organic salt, such as an organic tetrafluoroborate.

[0094] In some energy conversion and storage devices, a separator may be required to physically separate the electrodes and prevent short circuits. In supercapacitors, the separator is generally a porous material, such as a porous polymer, which allows for electrolyte storage and ion migration from the anode to the cathode during charging and discharging. The separator herein is not particularly limited, and those skilled in the art will be familiar with separators suitable for use in the devices herein. In one embodiment, the separator is made of a polymer, such as high-density polyethylene, polypropylene, PTFE, PET, or PTFE. In another embodiment, the separator is made of fibers, such as cellulose fibers, glass fibers, or aramid fibers.

[0095] [Method for producing slurry and electrode] Described herein is an electrode slurry for producing an electrode active layer, the electrode slurry comprising an active material, a binder comprising a salt of a sulfonated polymer, and a solvent.

[0096] The electrode slurry may include any suitable amount of solvent, for example, an amount sufficient to disperse the active material and achieve a viscosity that allows the electrode slurry to be spreadable on the conductive surface. In one embodiment, the electrode slurry includes about 60 to about 95 wt% solvent, or 60 to 80 wt%, or 75 to 90 wt%, or 80 to 95 wt% solvent, or 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, or 95 wt% solvent. The solvent is not particularly limited herein, but for environmental reasons, water is a preferred solvent. In one embodiment, the solvent is an organic solvent, such as methanol, ethanol, or X. In another embodiment, the solvent is water. In another embodiment, the solvent is a mixture of methanol or ethanol in water. Other suitable solvents will be apparent to those skilled in the art.

[0097] The electrode slurries herein may include any suitable weight percent of binder on a solids basis. In one embodiment, the electrode slurries herein include 1-30 wt%, or 1-10 wt%, or 5-20 wt%, or 10-25 wt%, or 15-30 wt%, or 2-20 wt%, or 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 12.5 wt%, 15 wt%, 17.5 wt%, 20 wt%, 25 wt%, or 30 wt%, of the binder on a solids basis.

[0098] As described elsewhere herein, the active material of the slurry may be the same as the active material of the electrode active layer.

[0099] The electrode slurry in this specification may contain any suitable weight percentage of active material based on a solid basis. In one embodiment, the electrode slurry in this specification contains 50-99 wt%, or 50-75 wt%, or 70-90 wt%, or 80-99 wt%, or 55-85 wt%, or 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, or 99 wt% of active material based on a solid basis.

[0100] In one embodiment, the electrode slurry is a substantially uniform dispersion of the active material. In one embodiment, the electrode slurry contains a substantially uniform dispersion of active material particles. In one embodiment, the electrode slurry contains a substantially uniform dispersion of active material particles and conductive particles. In one embodiment, the electrode slurry substantially has no agglomeration and aggregation of active material particles and / or conductive material particles. In one embodiment, the active material has a particle size distribution of D10>1 μm to D90<20 μm and 3 μm<D50<10 μm, or has a particle size distribution of D10>1 μm to D90<50 μm and 5 μm<D50<20 μm.

[0101] The electrode slurry may contain any suitable weight percentage of conductive material based on a solid basis. In one embodiment, the electrode slurry contains 5-25 wt%, or 5-10 wt%, or 7-15 wt%, or 10-20 wt%, or 15-25 wt%, or 10-25 wt% of conductive material based on a solid basis, or contains 5 wt%, 10 wt%, 15 wt%, 20 wt%, or 25 wt% of conductive material based on a solid basis.

[0102] The electrode slurry can be synthesized using any suitable technique in the art. In one embodiment, the binder is first dispersed in a solvent, such as water, followed by the addition of the active material and blending the resulting mixture. Blending conditions can include using a magnetic stirrer or other mechanical mixing device, and the blending step can be for any suitable time, such as from 1 minute to 48 hours, or from 1 hour to 24 hours, or from 5 minutes to 1 hour, or from 1 hour to 36 hours. In some embodiments, if a conductive material is used, the conductive material can be added after mixing / blending the active material, and the mixture can be blended for an additional time period of from 1 minute to 48 hours, or from 1 hour to 24 hours, or from 5 minutes to 1 hour, or from 1 hour to 36 hours.

[0103] In one embodiment, the mixture is dispersed using a high shear mixer for a period of 2 to 30 seconds, or 30 seconds to 5 minutes, or 2 minutes to 10 minutes, or 2 seconds to 30 minutes. The high shear dispersion may be suitably carried out after an initial mixing or blending step.

[0104] In other embodiments, the active material and conductive material are simultaneously dispersed in a binder / solvent mixture, for example in water, and subjected to one mixing step and an optional subsequent high shear dispersion step.

[0105] Also described herein is a method of fabricating an electrode active layer, comprising the steps of applying an electrode slurry described herein to an assembly; and drying the electrode slurry to remove the solvent.

[0106] The current collector is not particularly limited and may generally comprise any conductive material. In some embodiments, the current collector is a metal foil. Suitable metal foils may include aluminum foil or copper foil, although other metal foils may also be suitable. The current collector may have any suitable thickness. In some embodiments, the current collector is a metal foil having a thickness of 1 μm to 100 μm.

[0107] The applying step may include any suitable technique known in the art. In one embodiment, the applying step includes using screen printing, gravure printing, inkjet printing, slot die printing, K-bar coating, or the like to apply the electrode slurry to the current collector. In one embodiment, the electrode slurry is applied to the current collector in a thin layer, for example, a layer having a thickness of 1 μm to 100 μm, or a layer having a thickness of 10 μm to 1000 μm. In one embodiment, the layer is applied at substantially the same thickness across the current collector.

[0108] The drying step may include any suitable technique known in the art. In one embodiment, the electrode slurry on the current collector is dried in a vacuum oven, for example, at a temperature of 80-160°C for a period of 5 minutes to 24 hours under a reduced pressure of less than 200 mbar. During drying, the solvent evaporates, leaving the binder and active material, including any conductive materials, on the current collector. In some embodiments, about 100% of the solvent is removed during the drying step, or at least 90%, at least 95%, or at least 99% of the solvent is removed during the drying step.

[0109] [Embodiment] The following embodiments are disclosed herein: Embodiment 1. An active material, and a binder comprising a salt of a sulfonated polymer. Embodiment 2. The electrode active layer of embodiment 1, wherein the sulfonated polymer comprises substituted C2-C6 linear or branched alkene monomers. Embodiment 3. The sulfonated polymer comprises a substituted C2-C6 linear or branched alkene monomer, wherein the substituted C2-C6 linear or branched alkene has as a substituent -R1SO3 - , -R1ArSO3 - , -ArR1SO3 - , -ArSO3 - , or -C(=O)NHR1SO3 - , -C(=O)NHR1ArSO3 -, -C(=O)NHArR1SO3 - ; (Wherein R1=C1-C6 linear or branched alkyl group or bond; and 3. The electrode active layer of embodiment 1 or embodiment 2, comprising one or more of: Embodiment 4. The electrode active layer of embodiment 3, wherein Ar=phenyl group. Embodiment 5. The electrode active layer of any one of embodiments 1-4, wherein the sulfonated polymer comprises benzenesulfonate groups. Embodiment 6. The electrode active layer of any one of embodiments 1-5, wherein the sulfonated polymer comprises monomers containing one sulfonate group per monomer, optionally, monomers containing one benzenesulfonate group per monomer. Embodiment 7. The electrode active layer of any one of embodiments 1-6, wherein the sulfonated polymer comprises a monomer selected from styrene sulfonate, vinyl sulfonate, 2-acrylamido-2-methyl-1-propane sulfonate, 2-propene-1-sulfonate, or 2-methyl-2-propene-1-sulfonate. Embodiment 8. The electrode active layer of embodiment 7, wherein the sulfonated polymer comprises styrene sulfonate monomers. Embodiment 9. The electrode active layer of any one of embodiments 1-8, wherein the salt of the sulfonated polymer comprises one or more counterions selected from a Group I metal cation, a Group II metal cation, a transition metal cation, a quaternary ammonium cation, or a nitrogen-containing heterocyclic cation. Embodiment 10. The electrode active layer of any one of embodiments 1-9, wherein the salt of the sulfonated polymer comprises one or more counterions selected from lithium cations, potassium cations, sodium cations, cesium cations, magnesium cations, and calcium cations. Embodiment 11. The electrode active layer of any one of embodiments 1 to 10, wherein the salt of the sulfonated polymer comprises sodium cations, potassium cations, lithium cations, magnesium cations, and / or calcium cations. Embodiment 12. The electrode active layer of any one of embodiments 1-9, wherein the salt of the sulfonated polymer comprises one or more counterions selected from an optionally substituted alkylammonium cation, such as tetramethylammonium, tetraethylammonium, tetrapropylammonium, or tetrabutylammonium, or a 2-(methylthio)ethylammonium cation, or a nitrogen-containing heterocyclic cation, such as spiro-bis-pyrrolidinium (SBP), N,N-dimethylpyrrolidinium, N-methyl-N'-propylpyrrolidinium, N,N'-dimethylimidazolium, N-methyl-N'-ethylimidazolium, or N-methyl-N'-propylimidazolium. Embodiment 13. The electrode active layer of any one of embodiments 1 to 12, wherein the sulfonated polymer has an average molecular weight of about 50,000 g / mol to about 2,000,000 g / mol. Embodiment 14. The electrode active layer of embodiment 13, wherein the sulfonated polymer has an average molecular weight of about 70,000 g / mol to about 1,000,000 g / mol. Embodiment 15. The electrode active layer of any one of embodiments 1 to 14, wherein the binder comprises at least 30% by weight of a salt of a sulfonated polymer. Embodiment 16. The electrode active layer of embodiment 15, wherein the binder comprises at least 50% by weight of a salt of a sulfonated polymer. Embodiment 17. The electrode active layer of embodiment 15 or embodiment 16, wherein the binder comprises at least 90% by weight of a salt of a sulfonated polymer. Embodiment 18. The electrode active layer of any one of embodiments 1 to 17, wherein the sulfonate polymer is a copolymer comprising two or more different sulfonated monomers. Embodiment 19. The sulfonate polymer is a copolymer comprising one or more sulfonated monomers and at least one other monomer; the sulfonated monomer contains one sulfonate group per monomer; 19. The electrode active layer of any one of embodiments 1 to 18, wherein at least one other monomer does not have a sulfonate group. Embodiment 20. The electrode active layer of embodiment 19, wherein the sulfonated monomers contain one benzenesulfonate group per monomer. Embodiment 21. The electrode active layer of embodiment 19 or 20, wherein the at least one other monomer is selected from one or more of 1,2-difluoroethylene, tetrafluoroethylene, styrene, butadiene, maleic anhydride, maleic acid or a salt thereof, acrylic acid or a salt thereof, methacrylic acid or a salt thereof, or butylacrylic acid or a salt thereof. Embodiment 22. The electrode active layer of any one of embodiments 1 to 21, wherein the sulfonated polymer is a sulfonated partially fluorinated polymer. Embodiment 23. The electrode active layer of any one of embodiments 1 to 22, wherein the sulfonated polymer is a sulfonated non-fluorinated polymer. Embodiment 24. The electrode active layer of any one of embodiments 1 to 23, wherein the sulfonated polymer is not chemically crosslinked. Embodiment 25. The electrode active layer of any one of embodiments 1 to 24, wherein the binder comprises a mixture of two or more different salts of a sulfonated polymer, or a mixture of a salt of a sulfonated polymer and at least one other polymer. Embodiment 26. The electrode active layer of embodiment 25, wherein the other polymer is selected from PVDF, PTFE, SBR, or an acrylic polymer. Embodiment 27. The electrode active layer of any one of embodiments 1 to 26, wherein the active material is amorphous carbon. Embodiment 28. The electrode active layer of embodiment 27, wherein the active material is activated carbon. Embodiment 29. The electrode active layer of any one of embodiments 1 to 28, further comprising a conductive material. Embodiment 30. The electrode active layer of embodiment 29, wherein the conductive material is conductive carbon. Embodiment 31. The electrode active layer of any one of embodiments 1 to 30, having a thickness of 1 μm to 20 μm. Embodiment 32. The electrode active layer of any one of embodiments 1 to 31, wherein the binder is present in an amount of 1 to 30 wt % of the electrode active layer. Embodiment 33. The electrode active layer of embodiment 32, wherein the binder is present in an amount of 2 to 20 wt % of the electrode active layer. Embodiment 34. A composite electrode having an electrode active layer according to any one of embodiments 1 to 33 on a conductive surface. Embodiment 35. An energy storage device comprising the composite electrode according to embodiment 34. Embodiment 36. The energy storage device of embodiment 34, which is a supercapacitor. Embodiment 37. The energy storage device of embodiment 34, which is a battery. Embodiment 38. The energy storage device of any one of embodiments 35-37, comprising two composite electrodes, each composite electrode comprising a different binder. Embodiment 39. The energy storage device of embodiment 38, wherein the different binders comprise different sulfonated polymers. Embodiment 40. Use of a salt of a sulfonated polymer as a binder in the electrode active layer of a composite electrode. Embodiment 41. An electrode slurry for producing an electrode active layer, comprising: An active material; a binder comprising a salt of a sulfonated polymer; an electrode slurry comprising: a solvent; Embodiment 42. The electrode slurry of embodiment 41, comprising 50 to 95 wt % of a solvent. Embodiment 43. The electrode slurry of embodiment 41 or embodiment 42, wherein the solvent is water. Embodiment 44. The electrode slurry of any one of embodiments 41 to 43, comprising, on a solids basis, 1 to 30 wt % of the binder. Embodiment 45. The electrode slurry of embodiment 41, comprising 2 to 20 wt % of the binder on a solids basis. Embodiment 46. The electrode slurry of any one of embodiments 41-45, wherein the active material is amorphous carbon. Embodiment 47. The electrode slurry of embodiment 46, wherein the active material is activated carbon. Embodiment 48. The electrode slurry of any one of embodiments 41 to 47, comprising 50 to 99 wt % active material on a solids basis. Embodiment 49. The electrode slurry of any one of embodiments 41-47, wherein the slurry is a substantially uniform dispersion of the active material. Embodiment 50. The electrode slurry of any one of embodiments 41 to 49, further comprising a conductive material. Embodiment 51. The electrode slurry of embodiment 50, wherein the conductive material is conductive carbon. Embodiment 52. The electrode slurry of embodiment 50 or embodiment 51, comprising 5 to 25 wt % of the conductive material on a solids basis. Embodiment 53. The electrode slurry of any one of embodiments 41-52, wherein the sulfonated polymer is as in any one of embodiments 2-8, embodiments 13-14, or embodiments 18-24. Embodiment 54. The electrode slurry of any one of embodiments 41 to 53, wherein the salt of the sulfonated polymer is as in any one of embodiments 9 to 12. Embodiment 55: A process for applying the electrode slurry according to any one of embodiments 41 to 54 to a current collector; drying the electrode slurry to remove the solvent; A method for fabricating an electrode active layer, comprising: [Example]

[0110] The present invention is now described with reference to the following examples, which are to be considered in all respects as illustrative and not restrictive.

[0111] The effective capacitance is calculated using Equation 1:

[0112]

number

[0113] The effective ESR is calculated using Equation 2. Effective ESR (mΩ.cm 2 ) = ESR of the device (mΩ) × area of ​​one active electrode (cm 2 ) Equation 2

[0114] Example 1 [Polystyrene sulfonate binder mixture (NaPSS-100)] Water (3270 g), sodium polystyrene sulfonate (PSS; 46 g, MW = 1,000,000 g / mol, Sigma-Aldrich), carbon black (366 g), and activated carbon (1,338 g) were mixed and suspended, then physically coated onto aluminum foil using a K-bar, doctor blade, or slot die. Typical coating thicknesses applied ranged from 1 μm to 100 μm, depending on the equipment specifications.

[0115] [Test results and discussion] The coatings prepared from the binder mixtures described above were applied to a thickness of about 50 μm at 130° C. under a vacuum of less than 30 mbar, and the coated electrodes were formed into supercapacitors in a laminated package. The samples were tested in a test cell configuration at 70° C. and 2.5 V.

[0116] An equivalent coating prepared with CMC was also prepared in another identical supercapacitor. The initial effective ESR and capacitance for the PSS sample showed a significant decrease in effective ESR compared to the CMC sample, as shown in Table 1 below.

[0117] [Table 1]

[0118] The ESR and capacitance of the supercapacitors were tested by normal discharge measurements (see Figures 1 and 2). As these data reveal, with PSS as the binder, the ESR increases much slower and the capacitance is lost more slowly than with CMC. After 600 hours, the PSS capacitors performed better than the CMC capacitors operated at 50 hours.

[0119] The PSS supercapacitor also exhibits an improved frequency response of capacitance compared to another identical CMC supercapacitor (see Figure 3). The PSS supercapacitor -45° phase transition occurred at approximately 1.1 Hz compared to the equivalent CMC transition at 0.5 Hz (see Figure 4).

[0120] PSS-coated supercapacitors also exhibited improved gas release characteristics compared to identical CMC supercapacitors. Electrodes fabricated with either PSS or CMC as the binder were assembled in a two-electrode configuration and charged to 2.5 V in a sealed laminate package at 65 °C. The laminate cell was placed between two flat plates, one fixed and the other allowed to slide on a bearing. A load cell was attached to the free-moving flat plate. Gas release in the laminate cell was monitored as the force applied to the load cell increased as gas evolved in the laminate package; the results are shown in Figure 5. Less gas evolved in the supercapacitor cell using the PSS binder, as judged by the lower force applied to the load cell at 100 hours than in the equivalent CMC capacitor at 10 hours.

[0121] The NaPSS binder was most effective at a pH close to 7.

[0122] Example 2 [Polystyrene sulfonate binder mixture (NaPSS-70)] Water (2250 g), sodium polystyrene sulfonate (PSS; 74.1 g, MW = 70,000 g / mol), carbon black (147 g), and activated carbon (526 g) were mixed and suspended, then physically coated onto aluminum foil using a slot die. Typical coating thicknesses applied ranged from 1 μm to 100 μm, depending on the equipment specifications.

[0123] [Test results and discussion] The life tests of supercapacitors containing 70,000 g / mol of PSS binder and 1,000,000 g / mol of PSS binder were very similar, and both showed significant advantages over CMC supercapacitors in terms of ESR increase rate and C-loss rate (see Figures 6 and 7). The consistency of the data across various molecular weights of PSS indicates that the advantages of PSS are independent of polymer molecular weight in this range.

[0124] Example 3 [Polystyrene sulfonate binder mixture (X-PSS-75)] The electrode active layers were fabricated using various PSS salt binders: Ca-PSS-75, Mg-PSS-75, Li-PSS-75, K-PSS-75, and Cs-PSS-75.

[0125] PSS (acid, 75000 MW, 18% in HO) (7.52 g) was dissolved in deionized water (29.7 g) with magnetic stirring. The mixture was adjusted to pH 7 using Ca(OH) (saturated solution) and tetrafluoroboric acid. Methanol (0.83 g) was added and stirred for 10 minutes. Carbon black (2.72 g) was added and the mixture was stirred for 2 hours. Activated carbon (9.45 g) was added and stirred overnight, and finally the mixture was dispersed for 1 minute.

[0126] PSS (acid, 75000 MW, 18% in H2O) (3.82 g) was dissolved in deionized water (14.8 g) with magnetic stirring. The mixture was pH adjusted to 7 by adding Mg(OH)2 (approximately 0.14 g suspended in minimal water). Methanol (0.44 g) was added and stirred for 10 minutes. Carbon black (1.30 g) was added and the mixture was stirred for 2 hours. Activated carbon (4.72 g) was added and stirred overnight, and finally the mixture was dispersed for 1 minute.

[0127] PSS (acid, 75000 MW, 18% in HO) (3.74 g) was diluted in deionized water (16.32 g) with magnetic stirring. The mixture was pH adjusted to 8 with LiOH (approximately 0.088 g dissolved in minimal water). Tetrafluoroboric acid (48% in water) was added dropwise to adjust the pH to 8. Methanol (0.41 g) was added and stirred for 10 minutes. Carbon black (1.29 g) was added and the mixture was stirred for 2 hours. Activated carbon (4.65 g) was added and stirred overnight, and finally the mixture was dispersed for 1 minute.

[0128] PSS (acid, 75000 MW, 18% in HO) (3.76 g) was dissolved in deionized water (16.31 g) with magnetic stirring. The mixture was pH adjusted to 7-8 using KOH (approximately 0.21 g dissolved in minimal water) and tetrafluoroboric acid. Methanol (0.41 g) was added and stirred for 10 minutes. Carbon black (1.28 g) was added and the mixture was stirred for 2 hours. Activated carbon (4.61 g) was added and stirred overnight. Finally, the mixture was dispersed for 1 minute.

[0129] PSS (acid, 75000 MW, 18% in HO) (3.75 g) was dissolved in deionized water (16.59 g) using a magnetic stir bar. The mixture was pH adjusted to 7 using CsOH (added separately as a solid) and tetrafluoroboric acid. Methanol (0.42 g) was added and stirred for 10 minutes. Carbon black (1.32 g) was added and the mixture was stirred for 2 hours. Activated carbon (4.73 g) was added and stirred overnight, and finally the mixture was dispersed for 1 minute.

[0130] Each of the above mixtures was then physically coated onto aluminum foil using a K-bar. Typical coating thicknesses applied were on the order of 1 μm to 100 μm, depending on the equipment specifications.

[0131] [Test results and discussion] The initial effective capacitance and ESR results for a range of metal cations, including sodium, calcium, magnesium, potassium, cesium, and lithium cations, are shown in Table 2 below.

[0132] [Table 2]

[0133] Life tests of supercapacitors containing X-PSS-75 binder (X = K, Li, Cs, Mg, Ca) have ESR increase rates and C-loss rates as shown in Figures 8-9 (Ca, Mg) and Figures 10-11 (Li, K, Cs).

[0134] The data in Tables 2 and 1 and Figures 1-11 suggest that Na, Li, Mg, and Ca are particularly suitable counterions for PSS binders in supercapacitor devices that include activated carbon as the active electrode material.

[0135] Example 3 [Asymmetric / mixed binder equipment] Capacitors were constructed with PSS (NaPSS-70) as the binder in the positive electrode and SBR binder in the negative electrode (PSS-SBR) and vice versa (SBR-PSS).

[0136] [Test results and discussion] The C-loss rate and ESR increase rate are shown in Figures 12 and 13, respectively, for the asymmetric device. Other data in Figures 14-17 indicate that PSS can be used on either the positive or negative side, either alone or in combination with existing binders, without significant adverse effects on device life or performance.

[0137] Example 4 [Polystyrene sulfonic acid maleic anhydride copolymer binder mixture (NaPSS-coMA-20)] Poly(4-styrenesulfonic acid-co-maleic acid) sodium salt (MW 20000, Sigma-Aldrich) (2.31 g) was dissolved in deionized water (50.12 g) with magnetic stirring. The mixture was stirred for 1 hour. Carbon black (9.74 g) was added, and the mixture was mixed for 1 hour, then dispersed in a high-shear mixer for 1 minute. Activated carbon (20.24 g) was mixed and dispersed by adding water (12.58 g). The coating was then coated with a 20 μm K bar.

[0138] [Test results and discussion] Final thickness: 33.6±4.9 μm. Resistivity: 6.53 mΩ. The system passed a 1000 hour life test at 2.5 V. Poly(4-styrenesulfonic acid-co-maleic acid) sodium salt is a viable binder, with leakage results consistent with existing PSS data.

[0139] Although the present invention has been described in some detail for purposes of clarity and understanding, it will be apparent to those skilled in the art that various modifications and changes can be made to the embodiments and methods described herein without departing from the scope of the inventive concepts disclosed herein.

Claims

1. An active material; a binder comprising a salt of a sulfonated polymer; 1. An electrode active layer for an energy conversion or energy storage device, comprising:

2. The sulfonated polymer may be a substituted C ２ ~C ６ and optionally, the substituted C ２ ~C ６ The linear or branched alkene of the formula (I) is １ SO ３ － , -R １ ArSO ３ － , -ArR １ SO ３ － , -ArSO ３ － or —C(═O)NHR １ SO ３ － , -C(=O)NHR １ ArSO ３ － , -C(=O)NHArR １ SO ３ － ; (In the formula, R １ =C １ ~C ６ a straight or branched alkyl group or bond of 10. The electrode active layer of claim 1, wherein Ar=aryl group, optionally a phenyl group.

3. The electrode active layer of claim 1 , wherein the sulfonated polymer comprises benzenesulfonate groups.

4. 10. The electrode active layer of claim 1, wherein the sulfonated polymer comprises monomers containing one sulfonate group per monomer, optionally one benzenesulfonate group per monomer.

5. 2. The electrode active layer of claim 1, wherein the sulfonated polymer comprises one or more monomers selected from styrene sulfonate, vinyl sulfonate, 2-acrylamido-2-methyl-1-propane sulfonate, 2-propene-1-sulfonate, or 2-methyl-2-propene-1-sulfonate, optionally styrene sulfonate.

6. 2. The electrode active layer of claim 1, wherein the salt of the sulfonated polymer comprises one or more counterions selected from Group I metal cations, Group II metal cations, transition metal cations, quaternary ammonium cations, or nitrogen-containing heterocyclic cations.

7. 10. The electrode active layer of claim 1, wherein the salt of the sulfonated polymer comprises one or more counterions selected from lithium cations, potassium cations, sodium cations, cesium cations, magnesium cations, and calcium cations.

8. 2. The electrode active layer of claim 1, wherein the salt of the sulfonated polymer comprises one or more counterions selected from optionally substituted alkylammonium cations, such as tetramethylammonium, tetraethylammonium, tetrapropylammonium, or tetrabutylammonium, or 2-(methylthio)ethylammonium cations, or nitrogen-containing heterocyclic cations, such as spiro-bis-pyrrolidinium (SBP), N,N-dimethylpyrrolidinium, N-methyl-N'-propylpyrrolidinium, N,N'-dimethylimidazolium, N-methyl-N'-ethylimidazolium, or N-methyl-N'-propylimidazolium.

9. 10. The electrode active layer of claim 1, wherein the sulfonated polymer has an average molecular weight of from about 20,000 g / mol to about 2,000,000 g / mol, optionally from about 20,000 g / mol to about 1,000,000 g / mol.

10. 2. The electrode active layer of claim 1, wherein the binder comprises at least 30% by weight of the salt of the sulfonated polymer, optionally at least 50% by weight of the salt of the sulfonated polymer, or optionally at least 90% by weight of the salt of the sulfonated polymer.

11. 10. The electrode active layer of claim 1, wherein the sulfonate polymer is a copolymer comprising two or more different sulfonated monomers.

12. the sulfonate polymer is a copolymer comprising one or more sulfonated monomers and at least one other monomer; the sulfonated monomers contain one sulfonate group per monomer, optionally one benzenesulfonate group per monomer; 2. The electrode active layer of claim 1, wherein the at least one other monomer does not have a sulfonate group, and optionally the at least one other monomer is selected from one or more of 1,2-difluoroethylene, tetrafluoroethylene, styrene, butadiene, maleic anhydride, maleic acid or a salt thereof, acrylic acid or a salt thereof, methacrylic acid or a salt thereof, or butylacrylic acid or a salt thereof.

13. 2. The electrode active layer of claim 1, wherein the binder comprises a mixture of two or more different salts of a sulfonated polymer, or a mixture of a salt of a sulfonated polymer and at least one other polymer, optionally the other polymer being selected from PVDF, PTFE, SBR, or an acrylic polymer.

14. 10. The electrode active layer of claim 1, wherein the active material is amorphous carbon, optionally activated carbon.

15. The electrode active layer of claim 1 further comprising a conductive material, optionally conductive carbon.

16. A composite electrode comprising an electrode active layer according to any one of claims 1 to 15 on a conductive surface.

17. An energy storage device comprising the composite electrode of claim 16.

18. 18. The energy storage device of claim 17, which is a supercapacitor or a battery.

19. Use of a salt of a sulfonated polymer as a binder in the electrode active layer of a composite electrode.

20. An electrode slurry for producing an electrode active layer, An active material; a binder comprising a salt of a sulfonated polymer; an electrode slurry comprising: a solvent;

21. 21. The electrode slurry of claim 20 comprising 50 wt% to 95 wt% solvent, optionally wherein the solvent is water.

22. 21. The electrode slurry of claim 20, comprising, on a solids basis, from 1 wt % to 30 wt %, optionally from 2 wt % to 20 wt % of the binder.

23. 21. The electrode slurry of claim 20, wherein the slurry is a substantially uniform dispersion of the active material.

24. A step of applying the electrode slurry according to any one of claims 20 to 23 to a current collector; drying the electrode slurry to remove the solvent; A method for fabricating an electrode active layer, comprising:

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