Electrode slurry

Abstract

The present disclosure generally relates to an electrode paste composition comprising an electrode paste composition comprising: an electrode active material; a binder; the present invention relates to an electrode slurry composition comprising an electrode active material and a binder, and a microemulsion comprising an aqueous phase, a water immiscible phase, and an amphiphile wherein the electrode active material and the binder are incorporated within the microemulsion, which electrode slurry composition can be used to make electrodes, including for producing electrochemical cells.

Description

Technical Field

[0001] The present disclosure generally relates to electrode slurry compositions. Specifically, the present disclosure relates to electrode slurry compositions, which can be used to prepare electrodes, including for producing electrochemical cells. The present disclosure also relates to methods for preparing electrode slurry compositions, and methods for preparing electrodes from electrode slurry compositions. The present disclosure also relates to the use of electrode slurry compositions for preparing electrodes for electrochemical cells. The present disclosure also relates to electrochemical cells including electrodes prepared from electrode slurry compositions. Background Art

[0002] Energy consumption / generation that relies on the burning of fossil fuels is expected to have a serious future impact on the world economy and ecology. Electrochemical energy generation is being seriously considered as an alternative energy / power source, as long as this energy consumption is designed to be more sustainable and more environmentally friendly (Winter et al., "Chemical Review (Chem. Rev.)" 2004,104,10,4245-4270). Systems for electrochemical energy storage and conversion include electrochemical cells such as batteries (such as lithium-ion batteries), fuel cell units and supercapacitors. Although energy storage and conversion mechanisms are different, there is "electrochemical similarity" between these electrochemical cells. The common feature is that each requires a positive electrode and a negative electrode, and the energy providing process occurs at the phase boundary of the electrode / electrolyte interface, and electronic and ion transport are separated.

[0003] A key step that is almost universally used in the production of electrochemical cells such as batteries (e.g., lithium-ion batteries), fuel cell cells, and supercapacitors is to prepare electrodes by pasting a slurry made of electrode active materials, optional conductive agents, binders, and solvents onto a metal current collector. This coated current collector is then passed through an oven at high temperature to remove the solvent and leave only a film of solid material. Ideally, this film is robust, uniform, and has good adhesion to metals.

[0004] The solvent commonly used in industry is almost entirely N-methylpyrrolidone (NMP), and is widely used in industry and academic research because it gives the best results in terms of the desired electrode properties described above. NMP is an expensive, moisture-sensitive, environmentally harmful organic solvent, so finding a substitute for it is a top priority. Industry practice is to incorporate NMP recovery systems into production lines to recover evaporated NMP so that it can be recycled. The recovery of NMP is an energy-intensive process, and these systems are expensive. Therefore, there is a need for alternative or improved electrode slurry compositions for producing electrodes and electrodes for electrochemical cells that can solve one or more of the above-mentioned problems and / or provide the public with useful alternatives.

[0005] It should be understood that reference to any prior art publication herein does not constitute an admission that any of those documents forms part of the common general knowledge in the art, in Australia or any other country. Summary of the invention

[0006] The present disclosure provides specific electrode slurry compositions that can be used to prepare electrodes. The electrode slurry compositions described herein contain electrode active materials and microemulsions, rather than NMP as a solvent. Although water is an ideal solvent for use, this typically results in poor dispersibility of solid materials and poor film quality that breaks during drying. After extensive research and development, the inventors were surprised to find that microemulsions can be used in electrode slurry compositions to prepare high-quality electrodes. Advantageously, microemulsions replace expensive and dangerous NMP in electrode slurry compositions, thereby providing a cheaper and more environmentally friendly alternative. In addition, the physical and / or chemical properties of the microemulsions can be adjusted to develop specifically designed electrode slurry compositions to produce high-quality films for given electrode active materials, providing a general system for preparing a variety of electrodes.

[0007] In one aspect, an electrode slurry composition is provided, comprising: an electrode active material; a binder; and a microemulsion, wherein the microemulsion comprises an aqueous phase, a water-immiscible phase, and an amphiphile, wherein the electrode active material and the binder are incorporated into the microemulsion.

[0008] In another aspect, a method for preparing the electrode slurry composition described herein is provided, the method comprising mixing the microemulsion, an active material, and a binder under conditions effective to form the electrode slurry composition.

[0009] On the other hand, a method for preparing an electrode is provided, the method comprising the following steps: coating a first surface of a current collector with the electrode slurry composition described herein; heating the electrode slurry composition at a temperature and for a time period effective to dry the electrode slurry composition to form an electrode layer on the surface of the current collector, wherein the electrode layer comprises the electrode active material, a conductive material and a binder.

[0010] In another aspect, there is provided a use of the electrode slurry composition described herein in preparing an electrode for an electrochemical cell.

[0011] In another aspect, an electrochemical cell is provided, comprising a positive electrode (eg, cathode), a negative electrode (eg, anode), and an electrolyte, wherein the positive electrode and / or the negative electrode is prepared using the electrode slurry composition described herein.

[0012] These and other aspects and embodiments related to the present disclosure are further described herein. It should be understood that any one or more of the aspects, embodiments and examples described herein for the electrode slurry composition may also be suitable for any one or more of the aspects, embodiments and examples of the methods for preparing electrode slurry compositions, methods for preparing electrodes, electrode slurry compositions, electrodes and / or electrochemical cells described herein, and vice versa. Unless otherwise expressly stated, any embodiment, aspect or example described herein shall be deemed to be applicable to each other embodiment, aspect or example after making necessary modifications. It should also be understood that other aspects, embodiments and examples of electrode slurry compositions, methods, uses, electrodes and / or electrochemical cells are described herein.

[0013] It should also be understood that some features of the electrode slurry compositions, methods, uses, electrodes and / or electrochemical cells in some aspects, embodiments or examples as described herein may not be required for all aspects, embodiments or examples as described herein, and this specification will be read in this context. It should also be understood that in various aspects, embodiments or examples, the order of method or process steps may not be required and may vary. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The preferred embodiments of the present disclosure will now be further described and explained as follows, by way of example only, with reference to the accompanying drawings, in which

[0015] In the figure:

[0016] Figure 1 : Voltage-time diagram using the electrodes prepared in Table 2.

[0017] Figure 2 : Voltage-time diagram using the electrodes prepared in Table 3. DETAILED DESCRIPTION

[0018] The present disclosure describes the following various non-limiting embodiments, which relate to electrode slurry compositions that can be used to produce electrodes and electrochemical cells. The electrode slurry compositions described herein include electrode active materials and microemulsions, which are further described below according to various non-limiting embodiments and examples. Surprisingly, the electrode slurry compositions described herein provide one or more advantages, including the preparation of high-quality electrodes for electrochemical cells.

[0019] Those skilled in the art will appreciate that many changes and / or modifications may be made to the embodiments described above without departing from the general broad scope of the present disclosure. Therefore, the embodiments of the present invention should be considered to be illustrative and not restrictive in all aspects.

[0020] the term

[0021] In the following description, reference is made to the accompanying drawings, which form a part of the description and in which are shown by way of illustration several embodiments. It should be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present disclosure.

[0022] With respect to the definitions provided herein, unless otherwise stated or implied from the context, the defined terms and phrases include the meanings provided. Unless otherwise expressly stated or apparent from the context, the following terms and phrases do not exclude the meanings of the terms or phrases as acquired by those skilled in the relevant art. These definitions are provided to help describe specific embodiments, and these definitions are not intended to limit the claimed disclosure, as the scope of the present disclosure is limited only by the claims. In addition, unless the context otherwise requires, singular terms shall include the plural and plural terms shall include the singular.

[0023] All publications discussed and / or cited herein are incorporated herein in their entirety.

[0024] Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the present disclosure. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application.

[0025] Throughout this disclosure, references to individual steps, compositions of matter, groups of steps, or groups of compositions of matter shall be deemed to encompass one and multiple (i.e., one or more) of these steps, compositions of matter, groups of steps, or groups of compositions of matter, unless otherwise specifically stated or the context requires otherwise. Thus, as used herein, the singular forms "a," "an," and "the" include plural aspects unless the context clearly indicates otherwise. For example, reference to "a" includes a single as well as two or more; reference to "a" includes a single as well as two or more; reference to "the" includes a single as well as two or more, and so forth.

[0026] Those skilled in the art will appreciate that changes and modifications may be made to the disclosure herein, in addition to those specifically described. It should be understood that the disclosure includes all such changes and modifications. The disclosure also includes all examples, steps, features, methods, compositions, coatings, processes and coated substrates mentioned or indicated in this specification, individually or collectively, and any and all combinations of any two or more of the steps or features.

[0027] The term "and / or", such as "X and / or Y" should be understood to mean "X and Y" or "X or Y", and should be considered to provide clear support for both or either meanings.

[0028] Unless otherwise indicated, the terms "first," "second," and the like are used herein merely as labels and are not intended to impose ordinal, positional, or hierarchical requirements on the items to which these terms refer. Furthermore, reference to a "second" item does not require or preclude the presence of a lower-numbered item (e.g., a "first" item) and / or a higher-numbered item (e.g., a "third" item).

[0029] As used herein, when used with a list of items, the phrase "at least one of..." means that different combinations of one or more of the listed items may be used, and only one of each item in the list may be required. An item may be a specific object, thing, or category. In other words, "at least one of..." means that any combination of items or numbers of items in the list may be used, but not all items in the list may be required. For example, "at least one of item A, item B, and item C" may mean item A; item A and item B; item B; item A, item B, and item C; or item B and item C. In some cases, "at least one of item A, item B, and item C" may mean, for example, but not limited to, two of item A, one of item B, and ten of item C; four of item B and seven of item C; or some other suitable combination.

[0030] As used herein, unless stated to the contrary, the term "about" generally means + / - 10% of a specified value, such as + / - 5%.

[0031] It should be understood that, for the sake of clarity, certain features described herein in the context of separate embodiments may also be provided in a single embodiment in combination. Conversely, for the sake of brevity, various features described in the context of a single embodiment may also be provided individually or in any sub-combination.

[0032] Throughout this specification, various aspects and compositions of the present disclosure may be presented in a range format. The inclusion of a range format is for convenience and should not be interpreted as a fixed limitation on the scope of the present invention. Therefore, unless otherwise stated, the description of a range should be deemed to have explicitly disclosed all possible sub-ranges and individual numerical values ​​within the range. For example, the description of a range such as from 1 to 5 should be deemed to have specifically disclosed sub-ranges such as from 1 to 3, 1 to 4, 1 to 5, 2 to 4, 2 to 5, 3 to 5, etc., and single and partial numbers within the range, for example, 1, 2, 3, 4, 4.5 and 5, unless an integer or an implicit integer is needed in the context. No matter how wide the disclosed range is, this applies. When specific values ​​are needed, these values ​​will be indicated in the specification.

[0033] Throughout this specification, the word "comprise" or variations such as "comprises" or "comprising" should be understood to imply the inclusion of stated elements, integers or steps or groups of elements, integers or steps, but not the exclusion of any other elements, integers or steps or groups of elements, integers or steps.

[0034] Reference to "substantially free" generally means that the compound or component is not present in the composition, except for any trace amounts or impurities that may be present, for example, this may be an amount of less than about 1%, 0.1%, 0.01%, 0.001% or 0.0001% by weight of the total composition.

[0035] With respect to two or more materials, the term "immiscible" means that one material will not dissolve or combine with another material. With respect to immiscible liquids in a two-phase system, such as the microemulsions described herein, "immiscible" means that the liquids are either insoluble in each other, or so soluble in each other that for all practical purposes the liquids are generally considered to be immiscible in each other. When two immiscible liquids are combined in a system, a two-phase system of immiscible liquids is formed.

[0036] The terms "water" and "oil" (e.g., as used to refer to oil-in-water microemulsions and water-in-oil microemulsions) are understood to refer to an aqueous phase and a water-immiscible phase. The term "water-immiscible phase" is used to describe any liquid that is immiscible with the aqueous phase. As used herein, "water phase" and "aqueous phase" can be used interchangeably.

[0037] The term "slurry" refers to a liquid mixture containing solid particles.

[0038] Electrode slurry composition

[0039] The present disclosure covers various research and development related to identifying electrode slurry compositions that can be used to prepare electrodes, including electrodes for electrochemical cells. The electrode slurry compositions of the present disclosure include an electrode active material; a binder; and a microemulsion, the microemulsion comprising an aqueous phase, a water-immiscible phase, and an amphiphile, wherein the electrode active material, the binder are incorporated into the microemulsion. According to some embodiments or examples, the microemulsion and / or the electrode slurry composition are substantially free of N-methyl-2-pyrrolidone (NMP).

[0040] According to at least some embodiments or examples as described herein, one or more advantages of the present disclosure are that microemulsions can replace expensive and dangerous NMP in electrode slurry compositions, thereby providing a cheaper and more environmentally friendly system for preparing high-quality electrodes. The physical and / or chemical properties of the microemulsions can be adjusted to develop specifically designed electrode slurry compositions, thereby producing high-quality films for given electrode active materials, providing a general system for preparing a variety of electrodes.

[0041] Due to the presence of at least the electrode active material, binder and optional conductive material incorporated (e.g., dissolved / suspended / dispersed) in the microemulsion, the slurry has a solid content. In one embodiment, the solid content (% w / w) of the slurry is at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80 or 90 based on the total weight of the slurry. In one embodiment, the solid content (% w / w) of the slurry is less than about 90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2 or 1 based on the total weight of the slurry. The solid content can be a range provided by any two of these upper and / or lower limits, for example, based on the total weight of the slurry, the solid content (% w / w) of the slurry can be between about 1 to about 90, between about 10 to about 90, between about 20 to about 60, between about 30 to about 50, between about 1 to about 50, or between about 1 to about 10.

[0042] Although any amount of electrode active material can be used to prepare the slurries described herein, in one embodiment, the slurry contains between about 25% w / w to about 90% w / w of electrode active material based on the total weight of solids incorporated into the microemulsion. The slurry may contain at least about 25, 50, 55, 60, 65, 70, 75, 80, 85, or 90% w / w electrode active material based on the total weight of solids incorporated into the microemulsion. The slurry may contain less than about 90, 85, 80, 75, 70, 65, 60, 55, 50, or 25% w / w electrode active material based on the total weight of solids incorporated into the microemulsion. Based on the total weight of the solids incorporated in the microemulsion, the %w / w of the electrode active material can be a range provided by any two of these upper and / or lower limits, for example, based on the total weight of the solids incorporated in the microemulsion, the slurry can contain between about 50%w / w to about 90%w / w or between about 80%w / w to about 90%w / w of the electrode active material. Although any amount of binder can be used to prepare the slurries described herein, in one embodiment, based on the total weight of the solids incorporated in the microemulsion, the slurry contains a binder between about 1%w / w to about 20%w / w. Based on the total weight of the solids incorporated in the microemulsion, the slurry can contain at least about 1, 2, 4, 6, 8, 10, 12, 14, 16, 18 or 20%w / w binder. Based on the total weight of the solids incorporated in the microemulsion, the slurry can contain less than about 20, 18, 16, 14, 12, 10, 8, 6, 4, 2 or 1%w / w binder. The % w / w of binder based on the total weight of solids incorporated into the microemulsion can be a range provided by any two of these upper and / or lower limits, for example, the slurry can contain between about 1% w / w to about 10% w / w of binder based on the total weight of solids incorporated into the microemulsion.

[0043] If present, although any amount of conductive material can be used to prepare the slurries described herein, in one embodiment, the slurry contains between about 1% w / w to about 30% w / w of conductive material based on the total weight of solids incorporated into the microemulsion. The slurry can contain at least about 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 25, or 30% w / w conductive material based on the total weight of solids incorporated into the microemulsion. The slurry can contain less than about 30, 25, 20, 18, 16, 14, 12, 10, 8, 6, 4, 2, or 1% w / w conductive material based on the total weight of solids incorporated into the microemulsion. The % w / w of conductive material based on the total weight of solids incorporated into the microemulsion can be a range provided by any two of these upper and / or lower limits, for example, based on the total weight of solids incorporated into the microemulsion, the slurry can contain between about 5% w / w to about 20% w / w of conductive material.

[0044] microemulsion

[0045] The electrode slurry composition comprises a microemulsion. Electrode active materials, binders and other optional additives such as conductive agents are incorporated into the microemulsion. As used herein, the term "incorporation" generally refers to the ability of the microemulsion to serve as a suitable carrier for one or more of the components. For example, the electrode active material can be dispersed in the microemulsion as solid particles (e.g., suspended). Depending on its properties, the binder can be dissolved in the microemulsion (e.g., dissolved in the aqueous phase and / or water-immiscible phase of the microemulsion). Nevertheless, components dissolved or suspended in the microemulsion should be understood as "incorporated", as used herein.

[0046] As used herein, the term "microemulsion" refers to a thermodynamically stable mixture of two immiscible liquid phases. Microemulsions can be "oil-in-water" (O / W), "water-in-oil" (W / O) or "bicontinuous"; these terms that define the structure of microemulsions are well known in the art. In an oil-in-water microemulsion, a water-immiscible phase is dispersed in a continuous aqueous phase. In a water-in-oil microemulsion, an aqueous phase is dispersed in a continuous water-immiscible phase. In a bicontinuous microemulsion, the aqueous phase and the water-immiscible phase are each interconnected and dispersed throughout the mixture. Typically, a microemulsion has a microscopically heterogeneous liquid biphase structure that appears homogeneous at a macroscopic level. The aqueous phase and the water-immiscible phase of a microemulsion are immiscible at a desired operating temperature (usually room temperature or about room temperature). Microemulsions are thermodynamically stable and are therefore able to form spontaneously (without applying energy) and once formed will not separate into their constituent phases over time.

[0047] It should be emphasized that 'emulsions' are very different from microemulsions, despite their similar naming. Emulsions are thermodynamically unstable (kinetically stable) mixtures of immiscible liquids. This means that, in contrast to microemulsions, the two immiscible phases of the emulsion will separate over time. Unlike existing surfactant-free microemulsions, emulsions of immiscible liquids almost always require the presence of stabilizers to prevent phase separation, specifically surfactants or viscosity modifiers. For example, viscosity modifiers (e.g., thickeners such as polysaccharides) have previously been used to stabilize emulsions by slowing down droplet coalescence when the immiscible phases separate, which makes such viscosity modifiers referred to as emulsifiers or stabilizers, even though they are not surfactants / amphiphilic as understood in the art. Such highly viscous and thick emulsions may be more stable, but it is generally difficult to evenly disperse electrode active materials and binders therein, and once these components are incorporated, the entire slurry may have such a high viscosity due to the thickener that it is difficult to scrape onto the current collector, resulting in an uneven, non-uniform electrode layer, which results in a decrease in performance.

[0048] The microemulsion comprises an aqueous phase and a water-immiscible phase. In one embodiment, the microemulsion is an oil-in-water (O / W) microemulsion (i.e., the water-immiscible phase is dispersed in the aqueous phase, and the aqueous phase is a continuous phase). In an alternative embodiment, the microemulsion is a bicontinuous microemulsion (i.e., the water-immiscible phase and the aqueous phase are bicontinuous). In another embodiment, the microemulsion is an oil-in-oil (W / O) microemulsion (i.e., the water-immiscible phase is a continuous phase, and the aqueous phase is a dispersed phase). The type of microemulsion (e.g., O / W, W / O, or bicontinuous) can depend on the properties of the electrode active material, and is adjusted to develop a specifically designed electrode slurry composition, thereby producing a high-quality film for a given electrode active material. According to some embodiments or examples, it has been found that the electrode slurry composition comprising an oil-in-water (O / W) microemulsion can be used to prepare a high-quality electrode, as shown in the examples.

[0049] The solvent used as the water-immiscible phase of the microemulsion can include a water-immiscible solvent or a combination of two or more water-immiscible solvents. In one embodiment, the water-immiscible phase includes an organic solvent (e.g., a water-immiscible organic solvent). As an example only, a non-limiting list of solvents suitable for use as the water-immiscible phase of the microemulsion includes aliphatic solvents (e.g., cyclic and non-cyclic, branched and non-branched alkanes, such as hexane, cyclohexane and petroleum ether, olefins, alkynes); aromatic solvents (e.g., benzene, toluene, p-xylene, 1,2-dichlorobenzene); halogenated solvents (e.g., dichloromethane, chloroform, ethylene dichloride); ether solvents (e.g., ether, diphenyl ether); ketone solvents (e.g., acetophenone); ester solvents (e.g., ethyl benzoate, ethyl acetate); or combinations thereof.

[0050] In one embodiment, the organic solvent is selected from the group consisting of: an aliphatic solvent; an aromatic solvent; a halogenated solvent; a substantially water-immiscible ketone solvent; a substantially water-immiscible ether solvent; a substantially water-immiscible ester solvent, or a combination thereof.

[0051] In one embodiment, the organic solvent is selected from the group consisting of hexane, cyclohexane, petroleum ether, benzene, toluene, p-xylene, 1,2-dichlorobenzene, dichloromethane, chloroform, dichloroethane, ethyl acetate and diethyl ether, or a combination thereof.

[0052] In some embodiments, the boiling point of the organic solvent is less than about 150°C, close to the boiling point of water (a preferred component of the aqueous phase), and relatively lower than other higher boiling long chain compounds used to prepare the emulsion. In some embodiments, the boiling point of the organic solvent (in °C) is between about 20 and about 150.

[0053] In some embodiments, the boiling point difference between the water-immiscible phase and the water-miscible phase is between about 1° C. and about 100° C. (i.e., the difference between the boiling points of each phase). For example, if the water-miscible phase is water (boiling point of about 100° C.) and the water-immiscible phase is toluene (boiling point of about 110° C.), the boiling point difference is about 10° C. In some examples, the boiling point difference (in ° C.) between the water-immiscible phase and the water-miscible phase is between about 1 and about 100, between 1 and about 80, and between 10 and about 70.

[0054] In some examples, the microemulsion is prepared by using a water-immiscible phase having a boiling point close to or lower than the boiling point of water, which is a preferred component of the aqueous phase, providing additional advantages, such as the formation of a uniform electrode coating due to the lower heat required during the drying step described herein. In some preferred cases, the boiling point of the organic solvent as the water-immiscible phase can be similar to or lower than the boiling point of water, which is a preferred component of the aqueous phase.

[0055] According to some embodiments or examples described herein, organic solvents with relatively low boiling points and suitable aqueous phases such as water, once the electrode slurry is coated on the surface of the current collector, can be heated at a relatively low temperature and still effectively dried, thereby forming a uniform electrode layer on the surface of the current collector. Specifically, the inventors of the present application were surprised to find that using such low-boiling point organic solvents as water-immiscible phases, lower drying temperatures (e.g., less than about 200°C) can provide more uniform electrodes. In contrast, compared to water, water-immiscible phases containing long-chain higher alkanes, carboxylic acids or fatty acids, for example, have significantly higher boiling points (e.g., boiling points greater than 300°C), which means that the temperature required to dry the electrode slurry containing these long-chain compounds is much higher and will affect the integrity of the electrode, and therefore a more uniform electrode cannot be obtained at a lower drying temperature. Additionally, having one or more water-immiscible phases with similar boiling points means that the microemulsion composition remains similar throughout the drying process (e.g., no one phase is primarily removed before the other), in contrast to emulsions containing phases with very different boiling points, such as water and long-chain carboxylic acids, where the water will be removed first, leaving behind the long-chain carboxylic acids that take longer to remove (if at all) and may affect how the electrode progresses as it dries. Having a slurry in which the microemulsion phases dry at approximately the same rate (due to similar boiling points) will keep the formation of the electrode layer occurring under the same conditions throughout the drying process, rather than undergoing a stepwise drying regimen (i.e., a water removal regimen followed by a significantly higher boiling point phase removal regimen). In one embodiment, the concentration (% w / w) of the water-immiscible phase is at least about 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 99, based on the total weight of the microemulsion. In one embodiment, the concentration (% w / w) of the water-immiscible phase is less than about 99, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, 5 or 1 based on the total weight of the microemulsion. The % w / w concentration of the water-immiscible phase in the microemulsion can be a range provided by any two of these upper and / or lower limits, for example, the concentration (% w / w) of the water-immiscible phase can be between about 5 and about 95, between about 25 and about 75, or between about 40 and about 60 based on the total weight of the microemulsion. It should be understood that the concentration of the water-immiscible phase will vary depending on the type of microemulsion. For example, an O / W microemulsion will contain less water-immiscible phase than a W / O emulsion.

[0056] In embodiments where the microemulsion is an O / W microemulsion, the concentration (% w / w) of the water-immiscible phase can be between about 1 to about 60, between about 1 to about 50, between about 1 to about 40, or between about 1 to about 20, based on the total weight of the microemulsion.

[0057] In embodiments where the microemulsion is a bicontinuous microemulsion, the concentration (% w / w) of the water-immiscible phase may be between about 20 and about 80 based on the total weight of the microemulsion.

[0058] In embodiments where the microemulsion is a W / O microemulsion, the concentration of the water-immiscible phase (% w / w) can be between about 40 to about 99, between about 50 to about 99, between about 60 to about 99, or between about 80 to about 99, based on the total weight of the microemulsion.

[0059] In one embodiment, the aqueous phase comprises water. In another embodiment, the aqueous phase comprises a water-miscible solvent. In one embodiment, the aqueous phase comprises a mixture of water and a water-miscible solvent. The water-miscible solvent can be an alcohol, such as methanol, ethanol, propanol or amyl alcohol or a mixture thereof. It should be understood that the aqueous phase of the microemulsion electrolyte composition must be immiscible with the water-immiscible phase.

[0060] In one embodiment, the concentration (% w / w) of the aqueous phase is at least about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or 99 based on the total weight of the microemulsion. In one embodiment, the concentration (% w / w) of the aqueous phase is less than about 99, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10 or 5 based on the total weight of the microemulsion. The % w / w concentration of the aqueous phase in the microemulsion can be a range provided by any two of these upper and / or lower limits, for example, the concentration (% w / w) of the aqueous phase can be between about 5 and about 95, between about 25 and about 75, or between about 40 and about 60. It should be understood that the concentration of the aqueous phase will vary depending on the type of microemulsion. For example, an O / W microemulsion will contain more aqueous phase than a W / O emulsion.

[0061] In embodiments where the microemulsion is an O / W microemulsion, the concentration of the aqueous phase (% w / w) can be between about 40 to about 99, between about 50 to about 99, between about 60 to about 99, or between about 80 to about 99, based on the total weight of the microemulsion.

[0062] In embodiments where the microemulsion is a bicontinuous microemulsion, the concentration of the aqueous phase (% w / w) may be between about 20 and about 80 based on the total weight of the microemulsion.

[0063] In embodiments where the microemulsion is a W / O microemulsion, the concentration of the aqueous phase (% w / w) can be between about 1 to about 60, between about 1 to about 50, between about 1 to about 40, or between about 1 to about 20, based on the total weight of the microemulsion.

[0064] The relative proportion of the aqueous phase and the water-immiscible phase in the microemulsion is naturally limited by the overall thermodynamic stability of the mixture of the components that make up the microemulsion (e.g., aqueous phase, water-immiscible phase). There are natural restrictions on the relative proportion of each phase, where it is thermodynamically advantageous for the composition to exist as a microemulsion. There are other natural restrictions on the relative proportion of each phase, to obtain an oil-in-water microemulsion or a bicontinuous microemulsion. The relative proportion of each phase can be determined by those skilled in the art through theory or routine experiments. It should also be understood that the relative proportion of the aqueous phase and the water-immiscible phase includes any and all proportions and ranges in which a microemulsion is formed. Since oil-in-water and bicontinuous microemulsion systems are preferred, the preferred ratio of the aqueous phase and the water-immiscible phase is the ratio that produces oil-in-water and bicontinuous microemulsions.

[0065] The microemulsion further comprises one or more amphiphiles. As understood in the art, an amphiphile is a molecule with both a hydrophobic region and a hydrophilic region that stabilizes the microemulsion. Suitable amphiphiles are described herein, and selected amphiphiles are used in the examples, but the disclosure is not limited to these specific compounds. As understood by those skilled in the art, the selection of amphiphiles depends on the type of microemulsion desired (e.g., O / W, W / O, or bicontinuous), and / or the chemical properties and composition of the microemulsion or its components, and / or the specific identity and ratio of the components in the electrode slurry composition. In some cases, a suitable target microemulsion phase diagram can help identify the appropriate amount of phase and / or the type / amount of amphiphile to be used.

[0066] The amphiphile can be a surfactant, a co-surfactant or a co-solvent. In one embodiment, the microemulsion further comprises a surfactant. As understood in the art, a surfactant is a chemical compound that can reduce the surface or interfacial tension between the water-miscible phase and the water-immiscible phase of the microemulsion due to the presence of both a hydrophobic region and a hydrophilic region.

[0067] In one embodiment, the microemulsion further comprises a cosolvent. The cosolvent is generally fully or at least partially miscible with each of the phases of the microemulsion, thereby improving phase stability.

[0068] Suitable surfactants, co-surfactants and cosolvents that can be used as amphiphiles for preparing microemulsions will be known to those skilled in the art. Examples of suitable surfactants include anionic surfactants, cationic surfactants, zwitterionic surfactants and nonionic surfactants. Examples of preferred surfactants include Triton X-100, cetyltrimethylammonium bromide (CTAB), cetyltrimethylammonium chloride (CTAC), cetylpyridinium chloride (CPC), benzalkonium chloride, benzethonium chloride, sodium dodecyl sulfate (SDS) and sodium dodecyl ether sulfate (SLES). Examples of suitable co-surfactants or cosolvents include fatty alcohols such as C2-C6 alcohols, amines such as C2-C6 alkylamines and short chain carboxylic acids (C2-C6). Preferred co-surfactants and / or cosolvents of the present disclosure include ethanol, propanol, butanol and amyl alcohol. As will be appreciated by those skilled in the art, the selection of amphiphiles depends on the type of microemulsion desired (oil-in-water, bicontinuous or water-in-oil), and the specific identity and proportion of the components in the electrode slurry composition (e.g., electrode active material, binder, optional conductive material, etc.).

[0069] The factor used to determine the preferred relative proportions of the aqueous phase and the water-immiscible phase is the goal of achieving the desired incorporation of the electrode active material, binder material, and, if present, conductive material in the microemulsion.

[0070] As is clear from the foregoing description, the amounts of the various components in the microemulsion (e.g., aqueous phase, water-immiscible phase, and amphiphile, etc.) can be formulated or adjusted to optimize parameters so that the microemulsion can be customized according to the physical and chemical properties of the microemulsion, thereby developing a microemulsion specifically designed to achieve the desired incorporation of electrode active materials, binder materials, and, if present, conductive materials in the microemulsion. This customizability is advantageous because it can allow for the production of high-quality films of a variety of materials. Such optimization will be a matter of routine experimentation and is within the scope of the present disclosure.

[0071] Microemulsions can be prepared according to known methods for preparing microemulsions familiar to those skilled in the art. Microemulsions of the present disclosure can be prepared by combining the individual components. Since microemulsions are thermodynamically stable, they can form spontaneously. However, the microemulsion components can be agitated so that the microemulsion is formed in a suitably short period of time. For example, the combined components can be agitated by stirring, shaking, or ultrasonic treatment.

[0072] Microemulsions can be prepared under ambient conditions, ie, at room temperature and in the presence of ambient moisture, oxygen, carbon dioxide, and other atmospheric constituents.

[0073] In one embodiment, the concentration (% w / w) of the microemulsion is at least about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or 99, based on the total weight of the electrode slurry composition. In one embodiment, the concentration (% w / w) of the microemulsion is less than about 99, 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10 or 5, based on the total weight of the electrode slurry composition. The %w / w concentration of the microemulsion in the electrode slurry composition can be a range provided by any two of these upper and / or lower limits, for example, based on the total weight of the electrode slurry composition, the concentration of the microemulsion (%w / w) can be between about 5 and about 99, between about 10 and about 90, between about 40 and about 80, between about 50 and about 70, between about 50 and about 99, between about 60 and about 99, between about 70 and about 99, between 80 and about 99, or between about 90 and about 99.

[0074] Electrode active materials

[0075] The electrode slurry composition comprises an electrode active material, which is incorporated (e.g., dispersed) in a microemulsion. The electrode active material can be any electrochemically active substance that can be used as an electrode (e.g., a positive electrode or a negative electrode, such as a cathode or an anode) in an electrochemical cell. The electrode active material can be selected from any material known in the art. In one embodiment, the electrode active material comprises a positive electrode material (e.g., a cathode material). In one embodiment, the electrode active material comprises a negative electrode material (e.g., an anode material).

[0076] In one embodiment, the electrode active material can be selected from the group consisting of transition metal oxides or mixed metal oxides (e.g., lithium cobaltate, sodium metatitanate, lithium titanate, vanadium pentoxide), transition metal salts including transition metal phosphates and sulfates (e.g., lithium iron phosphate, sodium iron sulfate), vanadates (e.g., ammonium metavanadate), simple substances (e.g., sulfur), main group nitrides (e.g., boron nitride), main group oxides (e.g., boric anhydride), perylene and other organics (e.g., 3,4,9,10-perylene tetracarboxylic anhydride), Prussian blue, its analogs (e.g., iron (III) ferrocyanide), and carbon-based materials (e.g., carbon black, graphite, and activated carbon). However, it should be understood that the electrode slurry composition can contain essentially any electrode active material and represents a general system for preparing a variety of electrodes.

[0077] In one embodiment, the concentration (% w / w) of the electrode active material is at least about 1, 2, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 or 95, based on the total weight of the electrode slurry composition. In one embodiment, the concentration (% w / w) of the electrode active material is less than about 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, 10, 5, 4, 2 or 1, based on the total weight of the electrode slurry composition. The %w / w concentration of the electrode active material in the electrode slurry composition can be a range provided by any two of these upper and / or lower limits, for example, based on the total weight of the electrode slurry composition, the concentration of the electrode active material (%w / w) can be between about 1 to about 90, between about 8 to about 60, between about 10 to about 50, between about 1 to about 50, between about 1 to about 20, or between about 1 to about 10.

[0078] Adhesives

[0079] The electrode slurry composition includes a binder that is incorporated (e.g., dissolved) in a microemulsion. The binder holds the electroactive material together and helps adhere the electrode active material to the current collector. According to some embodiments or examples described herein, the introduction of the binder into the microemulsion allows the electrode coating to start directly from the slurry formation, and requires a single drying step that removes the microemulsion and cures the binder and adheres the electrode active material to the current collector, thereby providing a direct method for preparing an electrode layer.

[0080] The adhesive can be selected from any adhesive known in the art. In one embodiment, the adhesive is a polymer adhesive. In one embodiment, the adhesive is selected from the group consisting of: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR) or a combination thereof (such as a mixture of SBR and CMC).

[0081] In one embodiment, the concentration (% w / w) of the binder is at least about 0.01, 0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10, 12, 14, 16, 18, 20, or 30, based on the total weight of the electrode slurry composition. In one embodiment, the concentration (% w / w) of the binder is less than about 30, 20, 18, 16, 14, 12, 10, 5, 2, 1, 0.5, 0.2, 0.1, 0.05, or 0.01, based on the total weight of the electrode slurry composition. The %w / w concentration of the binder in the electrode slurry composition can be a range provided by any two of these upper and / or lower limits, for example, based on the total weight of the electrode slurry composition, the concentration of the binder (%w / w) can be between about 0.1 to about 30, between 0.2 to about 30, between about 0.5 to about 20, between about 0.7 to about 15, between about 0.1 to about 20, between about 0.1 to about 10, between about 0.1% to about 5, or between 0.1 to about 1.

[0082] In one embodiment, the binder is dissolved in the aqueous phase or the water-immiscible phase of the microemulsion. The advantage of having a slurry system based on a microemulsion is that the binder can be dissolved in the aqueous phase or the water-immiscible phase. This allows the use of a variety of possible binders and binder amounts. For example, binders with different solubility properties can be used without having to change the entire solvent system of the slurry, as long as it is soluble in at least one phase of the microemulsion.

[0083] Conductive Materials

[0084] The electrode slurry composition may further comprise a conductive material, which, if present, is incorporated (e.g., dispersed) in the microemulsion. Typically, the conductive material is added to improve the charge and discharge performance of the resulting electrode by forming a percolation network for electron transport in the electrode, which greatly improves the conductivity of the electrode. However, when the electrode active material is also conductive (e.g., graphite), a conductive material may not be required.

[0085] The conductive material can be selected from any material known in the art. In one embodiment, the conductive material is a carbon-based material. In another embodiment, the conductive material is carbon black. Carbon black can be of various types, such as "super-P" or "Ketjen black 600JD". Carbon black is particularly useful for increasing the conductivity of the electrode and reducing the resistance of the interaction. In another embodiment, the conductive material is graphite.

[0086] In one embodiment, the concentration (% w / w) of the conductive material is at least about 0.01, 0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10, 12, 14, 16, 18, 20, or 30, based on the total weight of the electrode slurry composition. In one embodiment, the concentration (% w / w) of the conductive material is less than about 30, 20, 18, 16, 14, 12, 10, 5, 2, 1, 0.5, 0.2, 0.1, 0.05, or 0.01, based on the total weight of the electrode slurry composition. The %w / w concentration of the conductive material in the electrode slurry composition can be a range provided by any two of these upper and / or lower limits, for example, based on the total weight of the electrode slurry composition, the concentration of the conductive material (%w / w) can be between about 0.2 to about 30, between about 0.5 to about 20, between about 0.7 to about 15, between 0.1 to about 30, between about 0.1 to about 10, between about 0.1 to about 5, or between about 0.1 to about 2.

[0087] additive

[0088] The electrode slurry composition may further comprise one or more additional additives. The additives may be added as a component of the microemulsion or as a separate component.

[0089] In one embodiment, the microemulsion may further comprise dissolved salts. The dissolved salts may be selected from the group comprising: Group 1 salts, Group 2 salts, transition metal salts, aluminum salts or combinations thereof. Examples of dissolved salts include, but are not limited to, LiCl, NaCl, KCl, LiOH, NaOH, KOH, MgSO4, MgCl2, Zn(NO3)2 and AlCl3. The aqueous phase may comprise dissolved salts. The aqueous phase may also comprise dissolved Group 1 ions, Group 2 ions, transition metal ions, aluminum ions or combinations thereof. Examples of dissolved ions include lithium, sodium, potassium, magnesium, aluminum, calcium, chromium, manganese, iron, cobalt, copper, nickel, zinc, silver, halogen ions (e.g., fluoride, chloride, chlorate, bromide, bromate, iodide, iodate), sulfate ions, nitrate ions and combinations thereof. The concentration of dissolved salts or ions in the aqueous phase may be between 0% and a saturated aqueous solution. Exemplary ranges of dissolved salts or ions include between 0M and 10M, more preferably between about 0.01M and 5M, more preferably between 0.05M and 1M, and most preferably between about 0.05M and 0.5M.

[0090] In one embodiment, the salt is added to the microemulsion once the microemulsion has been formed, or may be added to the aqueous component prior to preparing the microemulsion. In one embodiment, the salt is added to the aqueous component prior to preparing the microemulsion.

[0091] Method for preparing electrode slurry composition

[0092] In another aspect of the present disclosure, a method for preparing an electrode slurry composition is provided. The method for preparing an electrode slurry composition comprises mixing a microemulsion, an electrode active material, a binder, and a conductive agent if present, and mixing under conditions effective to form an electrode slurry composition.

[0093] The microemulsion, binder, electrode active material, and conductive material, if present, can be mixed at any suitable temperature to effectively form a slurry. For example, mixing can be carried out at a temperature (°C) of at least about 10, 15, 20, 25, 30, 35, 40, 45, or 50. Mixing can be carried out at a temperature (°C) of less than about 50, 45, 40, 35, 30, 25, 20, 15, or 10. The mixing temperature can be a range provided by any two of these upper and / or lower limits, such as the microemulsion, electrode active material, binder, and conductive agent, if present, can be mixed at a temperature (°C) between about 10 and about 50.

[0094] Microemulsion, adhesive, electrode active material and conductive material if present can be mixed to continue to effectively form the time period of slurry. For example, mixing can continue at least about 5,10,15,20,30,60 or 120 time periods (minutes). Mixing can continue to be less than about 120,60,30,20,15,10 or 5 time periods (minutes). Mixing time can be the scope provided by any two of these upper and / or lower limits, for example microemulsion, electrode active material, adhesive and conductive agent if present can be mixed to continue the time period (minutes) between about 5 to 120.

[0095] In one embodiment, the microemulsion, electrode active material, binder, and conductive agent, if present, are mixed for a period of time effective to form a homogeneous dispersion of the electrode active material, binder, and conductive agent, if present, within the microemulsion.

[0096] In one embodiment, the method comprises adding the microemulsion to the electrode active material, the binder, and the conductive agent, if present, and mixing under conditions effective to form an electrode slurry composition. In an alternative embodiment, the method comprises dissolving / suspending the binder in the microemulsion, then adding the microemulsion to the electrode active material and the conductive agent, if present, and mixing under conditions effective to form an electrode slurry composition.

[0097] Any suitable method may be used for mixing, such as magnetic stirring, planetary mixing or manual mixing. Alternatively or additionally, the slurry may be mixed under vacuum, or placed under vacuum after preparation. By doing so, additional advantages are provided, such as removing any dissolved gas present in the slurry (i.e., degassing). In one embodiment, the method comprises degassing the slurry.

[0098] electrode

[0099] The present disclosure also provides electrodes prepared using the electrode slurry compositions described herein.

[0100] In one aspect, a method for preparing an electrode is provided, the method comprising the following steps:

[0101] coating a first surface of a current collector with an electrode slurry composition comprising: an electrode active material; a binder; an optional conductive material; and a microemulsion comprising an aqueous phase and a water-immiscible phase, wherein the electrode active material, the binder, and, if present, the conductive material are incorporated into the microemulsion; and

[0102] The electrode slurry composition is heated at a temperature and for a time period effective to dry the electrode slurry composition to form an electrode layer on the surface of the current collector, wherein the electrode layer comprises the electrode active material, a binder, and, if present, a conductive agent.

[0103] The electrode may function as a positive electrode (eg, cathode) and / or a negative electrode (eg, anode).

[0104] The electrode slurry composition can be applied to the first surface of the current collector by any suitable method. In one embodiment, the electrode slurry composition is applied to the first surface of the current collector by transfer coating, slot die coating, scraping, dipping, screen printing, spraying or brushing. Coating is usually carried out at ambient temperature. If it is necessary to obtain an electrode slurry coating of suitable thickness, one or more coatings can be performed. In one embodiment, the electrode slurry composition is applied to the first surface of the current collector to provide an electrode slurry coating having a thickness (μm) of at least about 1, 2, 5, 10, 20, 50, 100, 200, 500, 1000, 5000 or 10,000. In one embodiment, the electrode slurry composition is applied to the first surface of the current collector to provide an electrode slurry coating with a certain thickness (μm). The thickness of the electrode slurry coating can be a range provided by any two of these upper and / or lower limits, for example, between about 1 μm and about 1 mm, preferably between about 50 μm and about 200 μm.

[0105] The electrode slurry composition and the current collector are typically heated together (e.g., by placing the coated current collector in an oven). The electrode slurry composition can be heated at a temperature and time period effective to form an electrode layer. This can include a temperature effective to cure the binder and / or dry and remove the microemulsion. The heating step can substantially remove at least the aqueous phase of the microemulsion (i.e., substantially remove water). In one embodiment, the electrode layer is substantially free of water.

[0106] In one embodiment, the electrode slurry composition is heated at a temperature (°C) of at least about 50, 70, 100, 110, 130, 150, 180 or 200. In one embodiment, the electrode slurry composition is heated at a temperature (°C) of less than about 200, 180, 150, 130, 110, 70 or 50. The heating temperature can be a range provided by any two of these upper and / or lower limits, such as between about 50 to about 200 or between about 100 to about 150. Such lower temperatures can provide a more uniform electrode. It should be understood that the duration of heating will depend on the temperature, wherein lower temperatures require longer heating times, and higher temperatures require shorter heating times. In one embodiment, the electrode slurry composition is heated for a period of time (hours) of at least about 0.1, 0.5, 1, 2, 4, 6, 9, 12, 18, 24 or 48. In one embodiment, the electrode slurry composition is heated for a period of time (hours) of less than about 48, 24, 18, 12, 9, 6, 4, 2, 1, 0.5 or 0.1. The heating time can be a range provided by any two of these upper and / or lower limits, such as between about 0.1 to about 48 hours or between about 6 to about 48 hours. In one embodiment, the slurry can be heated under vacuum.

[0107] It should be understood that the electrodes can be provided in any shape, size, thickness or configuration. Depending on the application, the electrodes can be provided within a certain thickness range. The thickness of the electrode can be controlled in part by the thickness of the electrode slurry coating.

[0108] The amount of slurry coating the first surface of the current collector can vary depending on the total target thickness of the electrode layer. In one embodiment, the thickness (μm) of the electrode layer is at least about 1, 2, 5, 10, 20, 50, 100, 200, 500, 1000, 5000 or 10,000. In one embodiment, the thickness (μm) of the electrode layer is less than about 10,000, 5000, 1000, 500, 200, 100, 50, 20, 10, 5, 2 or 1. The thickness of the electrode layer can be a range provided by any two of these upper and / or lower limits, for example, between about 1 μm and about 1 mm, preferably between about 50 μm and about 200 μm.

[0109] In one embodiment, in the method for preparing an electrode, the electrode layer and the current collector are compressed under a pressure that effectively increases the density of the electrode layer and / or promotes the contact between the surface of the current collector and the electrode layer. The electrode layer and the current collector can be compressed under a pressure (MPa) of at least about 0.1, 1, 2, 5, 10, 20, 40, 60, 80 or 100. The electrode layer and the current collector can be compressed under a pressure (MPa) of less than about 100, 80, 60, 40, 20, 10, 5, 2, 1 or 0.1. The compression pressure can be a range provided by any two of these upper and / or lower limits, such as a pressure (MPa) of about 0.1 to about 100.

[0110] The current collector can be any suitable current collector for preparing an electrode. The current collector can have a morphology and / or properties that effectively support the electrode slurry composition. In one embodiment, the current collector is a metal (e.g., steel) or carbon-based (e.g., graphite) current collector. In one embodiment, the current collector comprises an aluminum or copper current collector. In one embodiment, the current collector comprises aluminum or copper. In one embodiment, the current collector is in the form of a foil.

[0111] The current collector can have any suitable thickness. In one embodiment, the thickness of the current collector is between about 10 μm and about 1000 μm. The thickness of the current collector (in μm) can be at least about 10, 20, 50, 70, 100, 120, 150, 200, 250, 300, 350, 400, 500, 600, 800 or 1000. The thickness of the current collector (in μm) can be less than about 1000, 800, 600, 500, 400, 350, 300, 250, 200, 150, 120, 100, 70, 50, 20 or 10. The thickness can be a range provided by any two of these upper and / or lower limits, for example, between about 50 μm and about 500 μm.

[0112] The current collector may have a rough or textured surface that may provide an increased surface area, which facilitates the dispersion, incorporation or embedding of the electrode layer on or into the current collector. It should be understood that such surface roughening or texturing is understood to mean that the surface of the current collector has been manipulated (i.e., roughened or textured), and does not encompass a naturally "super flat" or polished surface that may have some form of microscopic roughness. In other words, the surface roughening is achieved by performing some physical or mechanical processing on the substrate surface, such as by grinding.

[0113] The current collector may initially be a sheet which, after forming the electrode layer on the surface of the current collector, is subsequently cut into appropriate sizes to form electrodes capable of being incorporated into an electrochemical cell.

[0114] In some embodiments, at least about 50, 60, 70, 80, 90, 95, or 98% of the surface of the current collector is covered with the electrode slurry composition / electrode layer.

[0115] In one embodiment, the method further comprises forming an electrochemical cell using the electrode.

[0116] Electrochemical battery cell

[0117] In another aspect of the present disclosure, an electrochemical cell is provided. It should be understood that the electrochemical cell comprises a positive electrode (e.g., a cathode) and a negative electrode (e.g., an anode) in fluid communication with an electrolyte. The positive electrode and / or the negative electrode can be prepared using the electrode slurry composition described herein.

[0118] In one aspect, an electrochemical cell is provided, the electrochemical cell comprising a positive electrode (e.g., a cathode), a negative electrode (e.g., an anode), and an electrolyte, wherein the anode and / or the cathode are prepared using the electrode slurry composition and method described herein. For example, the positive electrode and / or the negative electrode may comprise a current collector coated with an electrode layer prepared using the electrode slurry composition described herein.

[0119] The electrochemical cell can be suitable for any type of battery. For example, the electrochemical cell can be an ion battery or a flow battery. In one embodiment, the electrochemical cell is a lithium ion battery, a magnesium ion battery, a sodium ion battery, an aluminum ion battery or a supercapacitor.

[0120] In one embodiment, the electrochemical cell may be an ion battery or a flow battery. Preferably, the electrochemical cell may be a lithium ion battery, a magnesium ion battery, a sodium ion battery, an aluminum ion battery or a redox flow battery.

[0121] Electrochemical cells can be prepared using the electrodes described herein according to known methods. For example, a typical battery comprises a battery case of any suitable shape, standard or otherwise, made of a suitable material such as aluminum or steel for containing an electrolyte, and typically not plastic; battery terminals of a typical configuration; a positive electrode; a negative electrode; a separator for separating the positive and negative electrodes; and an electrolyte.

[0122] The electrode comprises a current collector. At least one of the positive electrode and / or the negative electrode comprises an electrode layer on the current collector, the electrode layer being prepared using the electrode slurry composition described herein.

[0123] Plasma cells such as lithium ion batteries can be constructed under ambient conditions using at least one electrode prepared by the method described herein. For example, a first electrode comprising an electrode layer on the surface of a current collector is placed in a main body (e.g., a plastic battery cell) with the electrode layer facing the inside. A glass microfiber filter is cut to a certain size and then placed on top of the first electrode as a separator. For small batteries, a suitable electrolyte between about 0.1 mL to about 1 mL is added on top of the glass microfiber before a second electrode comprising an electrode layer on the surface of a current collector is placed in the battery cell and the electrode layer faces the inside of the battery cell. The components are fixed and the battery cell is closed, for example, by tightening the closed battery cell.

[0124] Typically the battery will be in the form of a single cell, although multiple cells are possible. One or more cells may be in the form of a plate or spiral, or any other form. The positive and negative electrodes are electrically connected to the battery terminals.

[0125] The electrolyte may be any suitable electrolyte known to the skilled person and may be selected according to the type of electrochemical cell being developed. In one embodiment, the electrolyte comprises or consists of a microemulsion as described herein. Microemulsion electrolytes are also disclosed in PCT / NZ2019 / 050164, the contents of which are incorporated herein by reference. Alternatively, the electrolyte may comprise water, an organic solvent, or a mixture thereof. In one embodiment, the electrolyte may comprise water or one or more solvents selected from water, ethers, esters, carbonates, and acetals. In one example, the one or more electrolyte solvents are selected from 1,2-dimethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene carbonate, propylene carbonate, dimethyl carbonate, tetrahydrofuran, acetonitrile, and dioxolane, or a mixture thereof.

[0126] In one aspect, a use of the electrode slurry composition described herein in preparing an electrode for an electrochemical cell is provided. In another aspect, an electrode slurry composition described herein for preparing an electrochemical cell is provided.

[0127] This application claims priority to AU2022902023 filed on July 20, 2022, the entire contents of which are incorporated herein by reference.

[0128] Examples

[0129] The present disclosure is further described by the following examples. It should be understood that the following description is only for the purpose of describing specific embodiments and is not intended to limit the above description.

[0130] Example 1: Microemulsion

[0131] Microemulsion samples were prepared according to the following method. Each microemulsion sample contained an aqueous component and a water-immiscible component, optionally a cosolvent, optionally a surfactant and / or optionally a cosurfactant. The components of each microemulsion sample are shown in Table 1.

[0132] The surfactant is weighed into an Erlenmeyer flask, to which the water-immiscible component and the cosurfactant are added. The mixture is stirred thoroughly to form a uniform slurry, and then the aqueous component is added. The mixture is turbid and white, and when sonicated or stirred in an ultrasonic bath, a transparent microemulsion is formed.

[0133] ME2 and ME2i were prepared according to the method described in Menger, FM and Elrington, AR "Organic reactivity in microemulsion systems" Journal of the American Chemical Society (J.Am.Chem.Soc.) 113, 9621-9624 (1991), and the method for preparing ME2i is based on the present disclosure. ME4 was prepared according to the method described in Mukherjee, K., Mukherjee, DC and Moulik, SP "Thermodynamics of Microemulsion Formation" Journal of Colloid and Interface Science (J.ColloidInterface Sci.) 187, 327-333 (1997). ME14a and ME14b were prepared according to the method described in Gorel, F. "Assessment of agar gel loaded with microemulsion for the cleaning of porous surfaces" CeROArt Conserv. Expo. Restaur. D'Objets D'Art (2010).

[0134] For microemulsions containing dissolved salt, the required amount of salt was weighed and added to the prepared microemulsion.

[0135] Table 1: Microemulsion compositions for electrode slurry compositions

[0136] ME2i ME4 ME14a ME14b water 60 82 72.07 65.52 Toluene 15 - Cyclohexane - - 1.33 10.3 n-Butanol 16.67 10 Hexane - 3 SDS 8.33 - Triton X-100 - - 26.6 24.18 CTAB - 5

[0137] Example 2: Electrode slurry preparation

[0138] First, 300 mg of the dry slurry components were weighed out and added to a dry sample vial. The microemulsion was then added to the same vial along with a magnetic stirring bar. The resulting slurry was stirred vigorously until the desired consistency was reached and all materials were properly dispersed. This was all done under ambient conditions. The % w / w of the electrode active material, conductive carbon, and binder constituting the total 300 mg of dry slurry components, and the mL volume of the microemulsion used to prepare the slurry are listed in Tables 2-5.

[0139] Example 3: Electrode fabrication

[0140] The slurry was then coated onto graphite foil using a knife coater (MSK-AFA-HC100, MTI Corp.) to a wet film thickness of 200 microns. This was done with the help of a mask. The coated film was then placed in an extraction oven (UT20P, Heraeus Instruments) at 80°C for 2 hours and then in a vacuum oven (AI, PRDC3000, MTI Corp.) at 180°C for 12 hours. Appropriately sized electrodes were then cut from the larger sheets and weighed to determine the mass of electrode slurry on the electrodes. These electrodes were then stored until needed or used immediately.

[0141] Example 4: Test battery cell manufacturing

[0142] All cells prepared were Swagelok type cells. First, the electrode was placed on a glassy carbon current collector inside the cell housing with the active material facing the inside of the cell. Then, 1 or 2 glass microfiber (Whatman, GF-D) separators that had been cut to size were placed on top of the first electrode inside the cell housing. The appropriate electrolyte was then added, typically between 1 ml and 2 ml. The final electrode was then placed on top of the glass separator with the active material facing the inside of the cell. The second current collector was then placed on top of the second electrode and the entire cell was compressed to ensure good contact and a sealed closure.

[0143] Example 5: Electrode Performance

[0144] The assembled battery cell is connected to a battery analyzer capable of "constant current charge and discharge" experiments (Neware BTS4000 series 5V12A). The positive lead is connected to the positive electrode, and the negative lead is connected to the negative electrode. The battery cell is cycled 10 times with 500 mA per gram of electrode material (MW1, MW2) and 100 mA per gram of electrode material (MW3). The results are then analyzed to obtain suitable performance. The performance of the test battery cells containing the manufactured electrodes is summarized in Tables 2-5.

[0145]

[0146]

[0147]

[0148]

[0149] refer to Figure 1 and 2 , the voltage versus time plots show that the test cells containing the fabricated electrodes are stable and can be repeatedly charged to a voltage of 2.5V without visible signs of degradation, which would be observed as long irregular plateaus at or near the maximum voltage. The absence of any visible degradation highlights the stability of the fabricated electrodes. Additionally, the time taken for the charge-discharge cycle is constant over the test period, which also highlights the electrode stability. Poor quality electrodes will degrade and will quickly lose capacity, resulting in shorter cycles over time.

Claims

1. An electrode slurry composition comprising: Electrode active materials; Adhesives; and A microemulsion comprising an aqueous phase, a water-immiscible phase and an amphiphile, The electrode active material and the binder are incorporated into the microemulsion. 2 . The electrode slurry composition according to claim 1 , wherein the electrode slurry composition further comprises a conductive material.

3. An electrode slurry composition according to claim 1 or claim 2, wherein the microemulsion is substantially free of N-methyl-2-pyrrolidone (NMP).

4. The electrode slurry composition according to any one of claims 1 to 3, wherein the solid content (% w / w) of the electrode slurry is between about 1 to about 90, between about 1 to about 50, or between about 1 to about 10, based on the total weight of the slurry. 5 . The electrode slurry composition according to claim 1 , wherein the microemulsion is an oil-in-water (O / W) microemulsion, a water-in-oil (W / O) microemulsion, or a bicontinuous microemulsion.

6. The electrode slurry composition according to any one of claims 1 to 5, wherein the aqueous phase is water.

7. The electrode slurry composition according to any one of claims 1 to 6, wherein the water-immiscible phase comprises an organic solvent.

8. The electrode slurry composition according to any one of claims 1 to 7, wherein the organic solvent is selected from the group consisting of: an aliphatic solvent; an aromatic solvent; a halogenated solvent; a substantially water-immiscible ketone solvent; a substantially water-immiscible ether solvent; a substantially water-immiscible ester solvent; or a combination thereof.

9. The electrode slurry composition according to any one of claims 1 to 8, wherein the organic solvent is selected from the group consisting of hexane, cyclohexane, petroleum ether, benzene, toluene, p-xylene, 1,2-dichlorobenzene, dichloromethane, chloroform, dichloroethane, ethyl acetate and diethyl ether or a combination thereof.

10. The electrode slurry composition according to any one of claims 1 to 9, wherein the difference in boiling points between the water-immiscible phase and the water-miscible phase is between about 1°C and about 100°C.

11. The electrode slurry composition according to claim 10, wherein the amphiphile is a surfactant or a co-solvent or a mixture thereof. 12 . The electrode slurry composition according to claim 1 , wherein the surfactant is a cationic surfactant, an anionic surfactant, a zwitterionic surfactant or a nonionic surfactant.

13. The electrode slurry composition according to any one of claims 1 to 12, wherein the surfactant is selected from the group consisting of Triton X-100, cetyltrimethylammonium bromide (CTAB), cetyltrimethylammonium chloride (CTAC), cetylpyridinium chloride (CPC), benzalkonium chloride, benzethonium chloride, sodium dodecyl sulfate (SDS) and sodium lauryl ether sulfate (SLES).

14. The electrode slurry composition according to claim 13, wherein the co-solvent is an alcohol, an amine or a short-chain carboxylic acid.

15. The electrode slurry composition of claim 13 or claim 14, wherein the co-solvent is selected from the group consisting of ethanol, propanol, butanol and pentanol.

16. The electrode slurry composition according to any one of claims 1 to 15, wherein the microemulsion further comprises a dissolved salt, preferably selected from the group consisting of lithium salts, sodium salts, potassium salts, magnesium salts, calcium salts and aluminum salts.

17. The electrode slurry composition of any one of claims 1 to 16, wherein the amount of electrode active material (% w / w) in the electrode slurry composition is between about 1 to about 90, between about 1 to about 50, between about 1 to about 20, or between about 1 to about 10, based on the total weight of the slurry.

18. The electrode slurry composition of any one of claims 1 to 17, wherein the electrode active material comprises a positive electrode material (eg, a cathode material).

19. The electrode slurry composition according to any one of claims 1 to 18, wherein the electrode active material comprises a negative electrode material (eg, an anode material).

20. The electrode slurry composition according to any one of claims 1 to 19, wherein the electrode active material is selected from the group consisting of transition metal oxides or mixed metal oxides, transition metal salts, vanadates, simple substances, main group nitrides, main group oxides, perylene and other organics, Prussian blue, its analogs and carbon-based materials.

21. The electrode slurry composition of any one of claims 1 to 20, wherein the amount of binder in the electrode slurry composition (% w / w) is between about 0.1 to about 30, between about 0.1 to about 20, between about 0.1 to about 10, or between 0.1 to about 5, based on the total weight of the electrode slurry composition.

22. The electrode slurry composition of any one of claims 1 to 21, wherein the binder is dissolved in the aqueous phase or the water-immiscible phase.

23. The electrode slurry composition according to any one of claims 1 to 22, wherein the binder is selected from the group consisting of polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene butadiene rubber, or a mixture of styrene butadiene rubber and carboxymethyl cellulose, or a combination thereof.

24. The electrode slurry composition of any one of claims 1 to 23, wherein the amount of conductive material in the electrode slurry (% w / w) is between about 0.1 to about 30, between about 0.1 to about 10, or between about 0.1 to about 5, based on the total weight of the electrode slurry composition.

25. The electrode slurry composition of any one of claims 2 to 24, wherein the conductive material is a carbon-based conductive material.

26. The electrode slurry composition of claim 25, wherein the carbon-based conductive material is carbon black or a derivative thereof or graphene or a combination thereof.

27. A method for preparing an electrode slurry composition according to any one of claims 1 to 26, the method comprising mixing the microemulsion, electrode active material, binder and, if present, conductive agent under conditions effective to form the electrode slurry composition.

28. The method for preparing an electrode slurry composition according to claim 27, wherein the microemulsion, electrode active material, binder and conductive agent, if present, are mixed at a temperature between about 10°C to about 50°C.

29. A method for preparing an electrode slurry composition according to claim 27 or claim 28, wherein the microemulsion, electrode active material, binder and, if present, conductive agent are mixed for a period of time effective to form a homogeneous dispersion of the electrode active material, binder and, if present, conductive agent within the microemulsion.

30. A method for preparing an electrode slurry composition according to any one of claims 27 to 29, wherein the microemulsion, electrode active material, binder and, if present, conductive agent are mixed for a period of time between about 5 minutes to about 120 minutes.

31. A method for preparing an electrode, the method comprising the steps of: coating a first surface of a current collector with an electrode slurry composition according to any one of claims 1 to 26; heating the electrode slurry composition at a temperature and for a time effective to dry the electrode slurry composition to form an electrode layer on the surface of the current collector, The electrode layer comprises the electrode active material, a binder and, if present, a conductive material.

32. The method for preparing an electrode according to claim 31, wherein the thickness of the electrode layer is between about 1 μm and about 1 mm, preferably between about 50 μm and about 200 μm.

33. A method for preparing an electrode according to claim 31 or claim 32, wherein the electrode layer is substantially free of water.

34. A method for preparing an electrode according to any one of claims 31 to 33, wherein the electrode slurry composition is applied to the first surface of the current collector by transfer coating, slot die coating, doctor blading, dip coating, screen printing, spraying or brushing.

35. The method for preparing an electrode according to any one of claims 31 to 34, wherein the electrode slurry composition is heated at a temperature between about 50°C and 200°C.

36. The method for preparing an electrode according to any one of claims 31 to 35, wherein the electrode slurry composition is heated for a period of time (hours) between about 0.1 to about 48 hours.

37. A method for preparing an electrode according to any one of claims 31 to 36, wherein the electrode layer and current collector are compressed under a pressure effective to increase the density of the electrode layer and / or promote contact between the surface of the current collector and the electrode layer.

38. A method for preparing an electrode according to any one of claims 31 to 37, wherein the electrode layer and current collector are compressed at a pressure between about 0.1 MPa to about 100 MPa.

39. A method for preparing an electrode according to any one of claims 31 to 38, wherein the current collector is a metal or carbon based current collector.

40. A method for preparing an electrode according to any one of claims 31 to 39, wherein the metal-based current collector comprises aluminum or copper.

41. A method for preparing an electrode according to any one of claims 31 to 40, wherein the carbon-based current collector comprises graphite or graphene.

42. A method for preparing an electrode according to any one of claims 31 to 41, wherein the current collector is in the form of a foil.

43. A method for preparing an electrode according to any one of claims 31 to 42, wherein the electrode is a positive electrode (eg a cathode).

44. A method for preparing an electrode according to any one of claims 31 to 43, wherein the electrode is a negative electrode (eg, an anode).

45. Use of the electrode slurry composition according to 1 to 26 in preparing an electrode for an electrochemical cell.

46. ​​An electrochemical cell comprising a cathode, an anode and an electrolyte, wherein the positive electrode and / or the negative electrode is prepared using the method according to 31 to 44.

47. The electrochemical cell of claim 46, wherein the electrochemical cell is a lithium ion battery, a magnesium ion battery, a sodium ion battery, an aluminum ion battery, or a supercapacitor.

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