Method for manufacturing iron electrodes and articles and systems derived from said electrodes

Abstract

Iron electrode materials, iron electrodes, and methods for making the iron electrode materials and iron electrodes by high-temperature thermomechanical processing of porous particulate iron materials are described. For example, as part of iron electrode manufacturing, a particulate iron material may be provided to an apparatus, and pressure and / or heat may be applied to the particulate iron material within the apparatus for a period of time to form an electrode having conductive connections between particles of the particulate iron material.

Description

Technical Field

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 112,539, filed November 11, 2020, entitled "METHOD OF IRON ELECTRODE MANUFACTURE AND ARTICLES AND SYSTEMS THEREFROM" and U.S. Provisional Patent Application No. 63 / 193,424, filed May 26, 2021, entitled "METHOD OF IRON ELECTRODE MANUFACTURE AND ARTICLES AND SYSTEMS THEREFROM", the entire contents of both applications being incorporated herein by reference for all purposes.

Background Art

[0002] [[ID=~12]]Energy storage technologies are playing an increasingly important role in the power grid. At the most basic level, such energy storage assets provide smoothing to better match generation and demand in the distribution network. The services performed by energy storage devices are beneficial to the power grid over multiple time scales, from milliseconds to years. Today, there are energy storage technologies that can support time scales from milliseconds to hours, but long-term and ultra-long-term (collectively, >8 hours) energy storage systems are needed.

[0003] Direct reduced iron (DRI) is an inexpensive form of iron produced by reducing iron ore mainly to its metallic oxidation state. DRI is mainly available in pellet or lump form, with a characteristic size of 6 - 16 mm, which can vary depending on the pellets and lumps fed into the reduction process.

[0004] Iron anodes for energy storage applications (i.e., battery anodes) require high levels of microporosity (generally over 40% by volume), high specific surface area (generally around 0.05 square meters / g), and reasonably high purity (generally over 80% by weight of iron). Directly reduced iron satisfies all of the above material property requirements at an attractive price.

[0005] Other methods for producing highly porous iron materials (e.g., sponge iron) are often available at a price that is quite attractive for the manufacture of battery electrodes. These sponge irons may be produced in the form of fine particles. The contents of this disclosure may be useful for the consolidation of any iron-containing fine particle electrode material that is expected to benefit from creating electrical connections between particles for battery applications. Hereinafter, the term porous iron particles is used to describe any material having a high level of microporosity that can be arranged to be useful for electrical connections in order to form a battery material.

[0006] Battery electrodes must be conductive both ionically and electrically in order to function. While porous iron microparticles in particulate form are advantageous for bulk handling and manufacturing processes, the size and shape factors of the microparticles can pose problems when attempting to form a conductive material mass while substantially maintaining the porosity and microstructure within the porous iron microparticles. That is, electron transport through electrodes based on porous iron microparticles can be so difficult, for example, due to point contact resistance, that the performance of the electrode is limited by electron transport through the electrode. Often, electron transport through these electrodes can be enhanced by a suitable combination of conductive additives, compression to reduce contact resistance, or other techniques. However, these techniques for enhancing electrical conductivity within and outside the electrodes are often so expensive that the attractive applications of iron electrodes are no longer technically and economically appealing. Therefore, there is a need for economical techniques to provide electrical connectivity between porous iron microparticles for iron battery electrodes. [Overview of the project] [Problems that the invention aims to solve]

[0007] Techniques that succeed in connecting particles within an electrode not only produce electrodes with electrical conductivity and low cost, but also electrodes with low packaging cost and low current collector cost, providing a sufficiently robust battery in which the battery exhibits sufficient life for various applications. The methods, systems, and articles disclosed herein have unique potential to simultaneously address the above needs.

[0008] The background art above introduces various aspects of the art that may be associated with embodiments of the present disclosure. Thus, the above discussion provides a framework for better understanding the various disclosure aspects herein and should not be considered an admission of prior art.

Means for Solving the Problems

[0009] Without being limited to any particular theory or model regarding the reactivity of iron electrodes, a conceivable scheme for the oxidation of iron electrodes in an alkaline electrolyte can proceed according to the following two reaction steps, namely Reaction 1 and Reaction 2. Additional or different reaction products may occur (one of which is described in Reaction 3 below), but the characteristics of the volume change through the reaction may be common to any oxidation product regarding metallic iron. Reaction 1: Fe + 2OH - → Fe(OH)2 + 2e - E 0 = -0.88V vs SHE Reaction 2: 3Fe(OH)2 + 2OH - → Fe3O4 + 4H2O + 2e - E 0 = -0.76V vs SHE Reaction 3: Fe(OH)2 + OH - → FeOOH + H2O + e - E 0 = -0.61V vs SHE

[0010] Various embodiments include iron electrode materials, iron electrodes, and methods for producing the iron electrode materials and iron electrodes by high-temperature thermomechanical treatment of porous iron microparticles. Generally, the above techniques involve supplying, providing, or otherwise receiving the porous iron microparticles into an apparatus. Pressure and / or heat may be applied to the porous iron microparticles in the apparatus for a period of time to form electrodes having conductive connections between the particles of the iron microparticles. In some embodiments, the apparatus may apply pressure and high temperature to the material simultaneously to create strong conductive connections between the particles via metallurgical bonding. This thermomechanical treatment can yield a material composed of porous iron microparticles having metallurgical bonding at the contact points between the particles. Materials produced by the disclosed methods can be used as components of battery electrodes. Electrodes produced by this method can be low-cost, mechanically robust, highly scalable for mass production, and high-performance. The materials and electrodes manufactured by the methods disclosed herein are particularly suitable for iron battery applications for grid-scale energy storage, thereby potentially enabling large-scale adoption of renewable energy from intermittent energy sources such as wind and solar power. Electrodes manufactured by these methods are particularly attractive for commercial use in long-term energy storage due to the low number of components required for electrode assembly. Under appropriate processing conditions, electrodes manufactured by these methods may not require external current collection or packaging, and can rather be used as ready-to-use assemblies in electrochemical systems, potentially saving component and assembly costs compared to conventional electrode designs. In some embodiments, the disclosed methods can be scaled to very high production volumes with only minor modifications to existing manufacturing equipment already in place, with potential production volumes of several million tons per year in a single plant. This level of productivity is unattainable with other battery electrode manufacturing methods. The combination of cost, performance, and manufacturing scalability of the disclosed methods grants the right to store energy at hundreds of gigawatt-hours scale using these battery electrodes in existing manufacturing equipment, representing a shortcut to true grid-scale energy storage.

[0011] Various embodiments include an iron electrode comprising metallurgically bonded sponge iron particles, wherein the microporosity of the sponge iron particles is >50% by volume and the particle size of the sponge iron particles is >100 μm.

[0012] The accompanying drawings incorporated herein and constituting part of this specification illustrate exemplary embodiments of the claims and, together with the general description set forth above and the detailed description set forth below, serve to illustrate the features of the claims. [Brief explanation of the drawing]

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[0026] [Figure 1] This shows a comparison of the levels of deformation. [Figure 2] This describes an embodiment of hot rolling and densification in which mechanically and electrically connected materials are produced. [Figure 3] An example comparing unimodal and bimodal packing is shown. [Figure 4]The relationship between electrode thickness, DRI pellet size, and layer size is illustrated. [Figure 5] These are Ellingham diagrams of various elements. [Figure 6] This is an iron-carbon phase diagram. [Figure 7] Examples of tooling and pressing operations for forming channeled electrodes are shown according to various embodiments. [Figure 8] Examples of tooling and pressing operations for forming channeled electrodes are shown according to various embodiments. [Figure 9] Examples of toothed rollers suitable for forming channeled electrodes, according to various embodiments, are shown. [Figure 10] An overview of examples of channeled electrodes according to various embodiments is shown. [Figure 11] Examples of texture rollers and examples of operations for forming channeled electrodes according to various embodiments using such texture rollers are shown. [Figure 12] A side view of an example of a cutting or separation mechanism used to separate the formed electrode sheets is shown. [Figure 13] Examples of electrode connections according to various embodiments are shown. [Figure 14] This is an example of a structural surface (facing) application method using various embodiments. [Figure 15] This figure shows various exemplary systems in which one or more of the various embodiments can be used as part of a bulk energy storage system. [Figure 16] This figure shows various exemplary systems in which one or more of the various embodiments can be used as part of a bulk energy storage system. [Figure 17] This figure shows various exemplary systems in which one or more of the various embodiments can be used as part of a bulk energy storage system. [Figure 18]This figure shows various exemplary systems in which one or more of the various embodiments can be used as part of a bulk energy storage system. [Figure 19] This figure shows various exemplary systems in which one or more of the various embodiments can be used as part of a bulk energy storage system. [Figure 20] This figure shows various exemplary systems in which one or more of the various embodiments can be used as part of a bulk energy storage system. [Figure 21] This figure shows various exemplary systems in which one or more of the various embodiments can be used as part of a bulk energy storage system. [Figure 22] This figure shows various exemplary systems in which one or more of the various embodiments can be used as part of a bulk energy storage system. [Figure 23] This figure shows various exemplary systems in which one or more of the various embodiments can be used as part of a bulk energy storage system. [Modes for carrying out the invention]

[0027] Various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts. References to specific examples and implementations are illustrative and not intended to limit the scope of the claims. The following description of embodiments of the present invention is not intended to limit the invention to these embodiments, but rather to enable those skilled in the art to manufacture and use the invention. Unless otherwise noted, the accompanying drawings are not drawn to scale.

[0028] Where used herein, unless otherwise stated, room temperature is 25°C, and standard temperature and standard pressure are 25°C and 1 atm. Unless otherwise expressly stated, all tests, test results, physical properties, and values ​​that are temperature-dependent, pressure-dependent, or both are provided at standard ambient temperature and pressure.

[0029] Generally, the term “approximately” and the symbol “~(approximately)” as used herein, unless otherwise specified, mean to include a variation or range of ±10%, experimental error or instrument error associated with obtaining the stated value, preferably the greater of these.

[0030] Where used herein, unless otherwise specified, the enumeration of value ranges herein is intended merely as a simplified way of referring individually to each separate value that falls within the range. Unless otherwise indicated herein, each individual value within the range is incorporated herein as if it were individually enumerated herein.

[0031] As used herein, unless otherwise specified, the terms “%”, “weight%”, and “mass%” are used synonymously and refer to the weight of a first component as a percentage of the total weight of, for example, a formulation, mixture, particles, pellets, agglomerates, material, structure, or product. As used herein, unless otherwise specified, “volume%”, “% volume”, and similar terms refer to the volume of a first component as a percentage of the total volume of, for example, a formulation, mixture, particles, pellets, agglomerates, material, structure, or product.

[0032] As used herein, the term "microporous" refers to a material having pores (i.e., porosity) with a characteristic length scale of tens of microns or less.

[0033] The expression "volume % microporosity within a particle," as used herein, refers to the volume fraction of three-dimensionally penetrating voids within a microporous particle (i.e., the particle's geometric envelope). After thermomechanical treatment, this term is used to mean the volume fraction of three-dimensionally penetrating voids within the region occupied by the material of the deformed original particle. More simply, the particle is deformed, but in most cases, the original single particle can be identified to some extent where the deformation is not particularly severe. Volume % microporosity within a particle after thermomechanical treatment is the porosity within the identifiable region of the original particle.

[0034] The following examples are provided to illustrate various embodiments of the system and method of the present invention. These examples are illustrative, may be predictive, and should not be considered limiting, nor should they limit the scope of the invention in any way.

[0035] It should be noted that it is not necessary to provide or express the theories underlying any novel, groundbreaking processes, materials, performances, or other beneficial features and properties that are the subject matter of or associated with embodiments of the present invention. Nevertheless, various theories are provided herein to further advance the art of the art. The theories presented herein do not in any way limit, restrict, or narrow the scope of protection granted to the claimed invention unless otherwise expressly stated. Such theories may not be necessary for or in practice for the use of the present invention. Furthermore, it is understood that the present invention may be linked to new and previously unknown theories for describing the functional characteristics of embodiments of the methods, articles, materials, devices, and systems of the present invention. Such subsequently developed theories do not limit the scope of protection granted to the present invention.

[0036] Various embodiments of the systems, equipment, techniques, methods, activities, and operations shown herein can be used in various other activities and fields in addition to those shown herein. In addition, such embodiments can be used, for example, with other equipment or activities that may be developed in the future, and with existing equipment or activities that may be partially modified based on the teachings herein. Furthermore, the various embodiments and examples shown herein can be used together, whole or in part, and in various different combinations. Thus, the configurations provided in the various embodiments herein can be used together. For example, elements of an embodiment having A, A', and B, and elements of an embodiment having A'', C, and D can be used together in various combinations according to the teachings herein, for example, A, C, D, and A, A'', C, D, etc. Thus, the scope of protection given to the present invention should not be limited to specific embodiments, examples, or specific embodiments, configurations, or arrangements shown in specific figures.

[0037] Where used herein, unless otherwise specified, the term “specific gravity,” also known as apparent density, should be given the broadest possible meaning and generally refer to the weight per unit volume of a structure, such as the volumetric shape of a material. This property will include the internal porosity of the particles as part of their volume. This can be measured, among other techniques, with a low-viscosity fluid that wets the particle surface.

[0038] Where used herein, unless otherwise specified, the term “actual density,” sometimes also called true density, should be given the broadest possible meaning, generally referring to the weight per unit volume of a material when no voids are present in the material. This measurement and property essentially eliminates internal porosity from the material and does not include, for example, any voids in the material.

[0039] Therefore, the relationship between the three density properties can be explained using an aggregate of porous foam balls (e.g., Nerf® balls). The weight of the balls filling the container would be the bulk density of the balls.

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[0040] The weight of a single ball per unit spherical volume is likely its apparent density.

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[0041] The skeletal structure of the ball per unit volume of the remaining material, that is, the weight of the material constituting the ball after all void volume has been removed, would be the skeletal density.

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[0042] As used herein, unless otherwise specified, the terms agglomerates and aggregates should be given the broadest possible meaning, generally referring to aggregates of powdery particles.

[0043] Embodiments of the present invention include apparatus, systems, and methods for long-term and ultra-long-term low-cost energy storage. In this specification, “long-term” and “ultra-long-term” and similar terms should be given the broadest possible meaning unless otherwise expressly stated, and would include energy storage periods of 8 hours or longer, such as 8-hour energy storage periods, energy storage periods ranging from 8 to 20 hours, 20-hour energy storage periods, energy storage periods ranging from 20 to 24 hours, 24-hour energy storage periods, energy storage periods ranging from 24 hours to 1 week, and energy storage periods ranging from 1 week to 1 year (e.g., from a few days to several weeks, up to several months), and would include LODES systems. Furthermore, the terms “long-term” and “ultra-long-term,” “energy storage cell” including “electrochemical cell,” and similar terms should be given the broadest possible interpretation unless otherwise expressly stated, and would include electrochemical cells that may be configured to store energy over time ranges of several days, several weeks, or seasons.

[0044] In general, in embodiments, the long-term energy storage cell may be a long-term electrochemical cell. Generally, this long-term electrochemical cell can store electricity generated by a power generation system if: (i) the power source or fuel for that power generation is available, abundant, inexpensive, and combinations and variations thereof; (ii) the power needs or electricity demand of the grid, customers, or other users is less than the amount of electricity generated by the power generation system, the price paid to provide such power to the grid, customers, or other users is below the economically efficient point for generating such power (e.g., the cost of generation exceeds the market price of electricity), and combinations and variations thereof; and (iii) combinations and variations of (i) and (ii) and other reasons. This electricity stored in the long-term electrochemical cell can then be distributed to the grid, customers, or other users at an economically or otherwise required time. For example, an electrochemical cell may be configured to store energy generated by a solar cell during the summer months when sunlight is abundant and solar power generation exceeds the needs of the power grid, and to discharge the stored energy during the winter months when sunlight may be insufficient to meet the needs of the power grid.

[0045] Various embodiments of the use of directly reduced iron (DRI) as a material for batteries (or cells), as a component of batteries (or cells), and as combinations and variations thereof are considered. In various embodiments, DRI may be produced from or be a material obtained from the reduction of natural or processed iron ore, and such reduction is carried out without reaching the melting temperature of iron. In various embodiments, the iron ore may be taconite or magnetite or hematite or goethite, etc. In various embodiments, DRI may be in the form of pellets that are spherical or substantially spherical. In various embodiments, DRI may be porous and may contain open and / or closed pores. In various embodiments, DRI may include material that has been further treated by hot or cold briquetting. In various embodiments, DRI is obtained by reducing iron ore pellets to iron metal (Fe 0DRI can be produced by forming more metallic (more reduced, less oxidized) materials such as wustite (FeO), or composite pellets containing iron metal and residual oxide phases. In various non-limiting embodiments, DRI may be reduced iron ore taconite, directly reduced ("DR") taconite, reduced "blast furnace (BF) grade" pellets, reduced "electric arc furnace (EAF) grade" pellets, "cold directly reduced iron (CDRI)" pellets, DRI pellets, hot briquette iron (HBI), or any combination thereof. In the iron and steel industry, DRI is sometimes called "sponge iron," and its use is common, particularly in India. Embodiments of iron materials, including exemplary embodiments of DRI materials for use in the various embodiments described herein, including use as electrode materials, may have one, two or more, or all of the material properties listed in Table 1 below. As used herein, including in Table 1, the following terms have the following meanings unless otherwise expressly stated: “Specific surface area” means the total surface area of ​​the material per unit mass, including the surface area of ​​pores in porous structures; “Carbon content” or “Carbon (weight %)” means the mass of total carbon as a percentage of the total mass of DRI; “Cementite content” or “Cementite (weight %)” means the mass of Fe3C as a percentage of the total mass of DRI; “Total Fe (weight %)” means the mass of all iron as a percentage of the total mass of DRI; “Metallic Fe (weight %)” means the mass of Fe3C as a percentage of the total mass of DRI. 0 It means the mass of iron in its state; "metallized" is the percentage of the total mass of iron, Fe 0 This refers to the mass of iron in its state. As used herein, weight percentages, volume percentages, and apparent densities are understood to exclude any electrolytes or transient additives present in the pores unless otherwise stated. [Table 1]

[0046] *The specific surface area is preferably determined by the Brunauer-Emmett-Teller adsorption method ("BET"), more preferably BET as described in ISO 9277 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as methylene blue (MB) staining, ethylene glycol monoethyl ether (EGME) adsorption, electrokinetic analysis of complex ion adsorption, and protein retention (PR) methods, can provide results that can be correlated with BET results.

[0047] ** The actual density is preferably determined by the helium (He) gravity bottle method, more preferably as shown in ISO 12154 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests can be used to provide results that can be correlated with the results of the He gravity bottle method. The actual density may also be referred to in the art as “true density” or “skeleton density.”

[0048] *** The apparent density is preferably determined by immersion in water, and more preferably as shown in ISO 15968 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests can be used to provide results that can be correlated with the results of the He specific gravity bottle method. Porosity can be defined as the ratio of the apparent density to the actual density.

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[0049] **** d 孔、90%容積 This is preferably determined by mercury (Hg) intrusion porosimetry, more preferably as shown in ISO 15901-1 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as gas adsorption, can be used to provide results that can be correlated with the Hg intrusion results. d 孔、90%容積This is the pore diameter at which 90% of the total pore volume is located.

[0050] ***** d 孔、50%表面積 This is preferably determined by mercury (Hg) intrusion porosimetry, more preferably as shown in ISO 15901-1 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as gas adsorption, can be used to provide results that can be correlated with the Hg intrusion results. d 孔、50%表面積 This is the pore diameter at which 50% of the free surface area exists.

[0051] #Total Fe (wt%) is preferably determined by dichromate titration, more preferably as shown in ASTM E246-10 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as titration after tin(II) chloride reduction, titration after titanium(III) chloride reduction, and inductively coupled plasma (ICP) spectroscopy, can provide results that can be correlated with those obtained by dichromate titration.

[0052] ##Metallic Fe (wt%) is preferably determined by iron(III) chloride titration, more preferably as shown in ISO 16878 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as bromine-methanol titration, can be used to provide results that can be correlated with those obtained by iron(III) chloride titration.

[0053] ### The metallization (%) is preferably determined by the ratio of metallic Fe to total Fe, each of which is preferably determined by the method described above.

[0054] #### Carbon (wt%) is preferably determined by infrared absorption after combustion in an induction furnace, and more preferably as shown in ISO 9556 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as various combustion and inert gas melting techniques, including those shown in ASTM E1019-18, can provide results that can be correlated with infrared absorption after combustion in an induction furnace.

[0055] #####Fe 2+ The (wt%) is preferably determined by titration, and more preferably as shown in ASTM D3872-05 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as Mössbauer spectroscopy and X-ray absorption spectroscopy, can be used to provide results that can be correlated with those obtained by titration.

[0056] $Fe 3+ (Weight %) is preferably total Fe (weight %), metallic Fe (weight %), Fe 2+ (weight %) and Fe 3+ It is determined by the material balance relationships between (weight %) or within these. Specifically, Total Fe (weight %) = Metallic Fe (weight %) + Fe 2+ (Weight%)+Fe 3+ The equation (weight %) must be true by the law of conservation of mass, and therefore Fe 3+ (By weight %) is Fe 3+ (weight %) = Total Fe (weight %) - Metallic Fe (weight %) - Fe 2+ It can be calculated as a percentage (by weight).

[0057] $$SiO2 (wt%) is preferably determined by gravimetric methods, and more preferably as shown in ISO 2598-1 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as reduced molybdosilicate spectrophotometrics and X-ray diffraction (XRD), can provide results that can be correlated with gravimetric methods. In certain methods, SiO2 wt% is not determined directly, but rather the Si concentration (including neutral and ionic species) is measured and SiO2 wt% is calculated based on the stoichiometry of SiO2. That is, it is assumed that the molar ratio of Si:O is 1:2.

[0058] The ferrite (weight %) is preferably determined by X-ray diffraction (XRD).

[0059] $$$$Wustite (FeO, wt%, XRD) is preferably determined by X-ray diffraction (XRD).

[0060] Goethite (FeOOH, wt%), XRD is preferably determined by X-ray diffraction (XRD).

[0061] +Cementite (Fe3C, wt%, XRD) is preferably determined by X-ray diffraction (XRD).

[0062] In addition, embodiments of iron materials (including, for example, embodiments of DRI materials) for use in the various embodiments described herein, including use as electrode materials, may have one or more of the following properties, features, or characteristics, as shown in Table 2 (note that a value in one row or column may exist together with values ​​in a different row or column). [Table 2]

[0063] The total Fe (wt%) is preferably determined by dichromate titration, more preferably as shown in ASTM E246-10 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as titration after tin(II) chloride reduction, titration after titanium(III) chloride reduction, and inductively coupled plasma (ICP) spectroscopy, can provide results that can be correlated with those obtained by dichromate titration.

[0064] SiO2 (wt%) is preferably determined by gravimetric methods, and more preferably as shown in ISO 2598-1 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as reduced molybdosilicate spectrophotometrics and X-ray diffraction (XRD), can provide results that can be correlated with gravimetric methods. In certain methods, SiO2 wt% is not determined directly, but rather the Si concentration (including neutral and ionic species) is measured and SiO2 wt% is calculated based on the stoichiometry of SiO2. That is, it is assumed that the molar ratio of Si:O is 1:2.

[0065] Al2O3 (wt%) is preferably determined by flame atomic absorption spectrometry, more preferably as shown in ISO 4688-1 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as X-ray diffraction (XRD), can be used to provide results that can be correlated with flame atomic absorption spectrometry. In certain methods, Al2O3 wt% is not determined directly, but rather the Al concentration (including neutral and ionic species) is measured and Al2O3 wt% is calculated based on the stoichiometry of Al2O3. That is, it is assumed that the molar ratio of Al:O is 2:3.

[0066] !!!!MgO (wt%) is preferably determined by flame atomic absorption spectrometry, more preferably as shown in ISO 10204 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as X-ray diffraction (XRD), can be used to provide results that can be correlated with flame atomic absorption spectrometry. In certain methods, MgO wt% is not determined directly, but rather the Mg concentration (including neutral and ionic species) is measured and the MgO wt% is calculated assuming the stoichiometry of MgO. That is, it is assumed that the molar ratio of Mg:O is 1:1.

[0067] CaO (wt%) is preferably determined by flame atomic absorption spectrometry, more preferably as shown in ISO 10203 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as X-ray diffraction (XRD), can be used to provide results that can be correlated with flame atomic absorption spectrometry. In certain methods, CaO wt% is not determined directly, but rather the Ca concentration (including neutral and ionic species) is measured and the CaO wt% is calculated assuming a stoichiometry of CaO. That is, it is assumed that the molar ratio of Ca:O is 1:1.

[0068] TiO2 (wt%) is preferably determined by diantipyrimethane spectrophotometry, more preferably as shown in ISO 4691 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as X-ray diffraction (XRD), can be used to provide results that can be correlated with diantipyrimethane spectrophotometry. In certain methods, TiO2 wt% is not determined directly, but rather the Ti concentration (including neutral and ionic species) is measured and TiO2 wt% is calculated based on the stoichiometry of TiO2. That is, it is assumed that the molar ratio of Ti:O is 1:2.

[0069] The actual density is preferably determined by the helium (He) gravity bottle method, more preferably as shown in ISO 12154 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests can be used to provide results that can be correlated with the results of the He gravity bottle method. The actual density may also be referred to in the art as “true density” or “skeleton density”.

[0070] The apparent density is preferably determined by immersion in water, and more preferably as shown in ISO 15968 (the disclosure in this document is incorporated herein by reference in its entirety). It is recognized that other tests can be used to provide results that can be correlated with the results of the He specific gravity bottle method.

[0071] &&&&Bulk density (kg / m 3 ) is preferably determined by measuring the mass of a test portion introduced into a container of known volume until its surface is filled to the brim, and more preferably as shown in Method 2 of ISO 3852 (the disclosure of this document is incorporated herein by reference in its entirety). It is recognized that other tests can be used to provide results that can be correlated with the results of the mass measurement method.

[0072] Porosity is preferably determined by the ratio of apparent density to actual density.

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[0073] Furthermore, the characteristics shown in Table 1 may be present in embodiments, in addition to or instead of, the characteristics in Table 2. Larger and smaller values ​​of these characteristics may also exist in various embodiments.

[0074] In this embodiment, the specific surface area of ​​the pellet is approximately 0.05 m². 2 / g ~ approx. 35m 2 / g, approx. 0.1m 2 / g~about 5m 2 / g, approx. 0.5m 2 / g~about 10m 2 / g, approx. 0.2m 2 / g~about 5m 2 / g, approx. 1m 2 / g~about 5m 2 / g, approx. 1m 2 / g~about 20m 2 It may also be / g, which is about 1m 2 It can be larger than / g, approximately 2m 2 It can be larger than / g, approximately 5m 2 It may be less than / g, approximately 15m 2 It may be less than / g, approximately 20m 2 It may be less than / g, as well as combinations and variations thereof, as well as larger and smaller values.

[0075] Generally, iron ore pellets are produced by crushing, grinding, or milling iron ore into a fine powder form, and then concentrated by removing impurity phases (so-called "gangues") released during the grinding process. Generally, grinding the ore to a finer (smaller) particle size increases the purity of the resulting concentrate. The concentrate is then formed into pellets by a pelletizing or balling process (e.g., using drum or disc pelletizers). Generally, producing higher purity ore pellets requires more energy input. Iron ore pellets are generally commercially available or sold in two main categories: blast furnace (BF) grade pellets and direct reduction (DR) grade (sometimes also called electric arc furnace (EAF) grade). The main difference is the SiO2 content, with other impurity phases being more abundant in BF grade pellets compared to DR grade pellets. Typical and important specifications for DR grade pellets or feedstock are that the total Fe content by mass percentage is in the range of 63-69% (e.g., 67% by mass), and the SiO2 content by mass percentage is less than 3% (e.g., 1% by mass). Typical and important specifications for BF grade pellets or feedstock are that the total Fe content by mass percentage is in the range of 60-67% (e.g., 63% by mass), and the SiO2 content by mass percentage is in the range of 2-8% (e.g., 4% by mass).

[0076] In certain embodiments, DRI can be produced by the reduction of "blast furnace" pellets, in which case the resulting DRI may have the material properties described in Table 3 below. The use of reduced BF grade DRI may be advantageous because it requires less input energy to produce the pellets, which in other words means a lower cost for the finished product. [Table 3]

[0077] *The specific surface area is preferably determined by the Brunauer-Emmett-Teller adsorption method ("BET"), more preferably BET as described in ISO 9277 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as methylene blue (MB) staining, ethylene glycol monoethyl ether (EGME) adsorption, electrokinetic analysis of complex ion adsorption, and protein retention (PR) methods, can provide results that can be correlated with BET results.

[0078] ** The actual density is preferably determined by the helium (He) gravity bottle method, more preferably as shown in ISO 12154 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests can be used to provide results that can be correlated with the results of the He gravity bottle method. The actual density may also be referred to in the art as “true density” or “skeleton density.”

[0079] *** The apparent density is preferably determined by immersion in water, and more preferably as shown in ISO 15968 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests can be used to provide results that can be correlated with the results of the He specific gravity bottle method. Porosity can be defined as the ratio of the apparent density to the actual density.

number

[0080] **** d 孔、90%容積 This is preferably determined by mercury (Hg) intrusion porosimetry, more preferably as shown in ISO 15901-1 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as gas adsorption, can be used to provide results that can be correlated with the Hg intrusion results. d 孔、90%容積This is the pore diameter at which 90% of the total pore volume is located.

[0081] ***** d 孔、50%表面積 This is preferably determined by mercury (Hg) intrusion porosimetry, more preferably as shown in ISO 15901-1 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as gas adsorption, can be used to provide results that can be correlated with the Hg intrusion results. d 孔、50%表面積 This is the pore diameter at which 50% of the free surface area exists.

[0082] #Total Fe (wt%) is preferably determined by dichromate titration, more preferably as shown in ASTM E246-10 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as titration after tin(II) chloride reduction, titration after titanium(III) chloride reduction, and inductively coupled plasma (ICP) spectroscopy, can provide results that can be correlated with those obtained by dichromate titration.

[0083] ##Metallic Fe (wt%) is preferably determined by iron(III) chloride titration, more preferably as shown in ISO 16878 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as bromine-methanol titration, can be used to provide results that can be correlated with those obtained by iron(III) chloride titration.

[0084] ### The metallization (%) is preferably determined by the ratio of metallic Fe to total Fe, each of which is preferably determined by the method described above.

[0085] #### Carbon (wt%) is preferably determined by infrared absorption after combustion in an induction furnace, and more preferably as shown in ISO 9556 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as various combustion and inert gas melting techniques, including those shown in ASTM E1019-18, can provide results that can be correlated with infrared absorption after combustion in an induction furnace.

[0086] #####Fe 2+ The (wt%) is preferably determined by titration, and more preferably as shown in ASTM D3872-05 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as Mössbauer spectroscopy and X-ray absorption spectroscopy, can be used to provide results that can be correlated with those obtained by titration.

[0087] Fe 3+ (Weight %) is preferably total Fe (weight %), metallic Fe (weight %), Fe 2+ (weight %) and Fe 3+ It is determined by the material balance relationships between (weight %) or within these. Specifically, Total Fe (weight %) = Metallic Fe (weight %) + Fe 2+ (Weight%)+Fe 3+ The equation (weight %) must be true by the law of conservation of mass, and therefore Fe 3+ (By weight %) is Fe 3+ (weight %) = Total Fe (weight %) - Metallic Fe (weight %) - Fe 2+ It can be calculated as a percentage (by weight).

[0088] $$SiO2 (wt%) is preferably determined by gravimetric methods, and more preferably as shown in ISO 2598-1 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as reduced molybdosilicate spectrophotometrics and X-ray diffraction (XRD), can provide results that can be correlated with gravimetric methods. In certain methods, SiO2 wt% is not determined directly, but rather the Si concentration (including neutral and ionic species) is measured and SiO2 wt% is calculated based on the stoichiometry of SiO2. That is, it is assumed that the molar ratio of Si:O is 1:2.

[0089] The ferrite (weight %) is preferably determined by X-ray diffraction (XRD).

[0090] $$$$Wustite (FeO, wt%, XRD) is preferably determined by X-ray diffraction (XRD).

[0091] Goethite (FeOOH, wt%), XRD is preferably determined by X-ray diffraction (XRD).

[0092] +Cementite (Fe3C, wt%, XRD) is preferably determined by X-ray diffraction (XRD).

[0093] Furthermore, the characteristics shown in Table 3 may be present in embodiments, in addition to or instead of, the characteristics in Tables 1 and / or 2. Larger and smaller values ​​of these characteristics may also exist in various embodiments.

[0094] In certain embodiments, DRI can be produced by reducing DR-grade pellets, in which case the resulting DRI may have the material properties described in Table 4 below. The use of reduced DR-grade DRI may be advantageous because it has a higher Fe content in the pellets, thereby increasing the energy density of the battery. [Table 4]

[0095] * The specific surface area is preferably determined by the Brunauer-Emmett-Teller adsorption method ("BET"), more preferably BET as described in ISO 9277 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as methylene blue (MB) staining, ethylene glycol monoethyl ether (EGME) adsorption, electrokinetic analysis of complex ion adsorption, and protein retention (PR) methods, can provide results that can be correlated with BET results.

[0096] ** The actual density is preferably determined by the helium (He) gravity bottle method, more preferably as shown in ISO 12154 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests can be used to provide results that can be correlated with the results of the He gravity bottle method. The actual density may also be referred to in the art as “true density” or “skeleton density.”

[0097] *** The apparent density is preferably determined by immersion in water, and more preferably as shown in ISO 15968 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests can be used to provide results that can be correlated with the results of the He specific gravity bottle method. Porosity can be defined as the ratio of the apparent density to the actual density.

number

[0098] **** d 孔、90%容積This is preferably determined by mercury (Hg) intrusion porosimetry, and more preferably as shown in ISO 1 5901-1 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as gas adsorption, can be used to provide results that can be correlated with the Hg intrusion results. d 孔、90%容積 This is the pore diameter at which 90% of the total pore volume is located.

[0099] ***** d 孔、50%表面積 This is preferably determined by mercury (Hg) intrusion porosimetry, more preferably as shown in ISO 15901-1 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as gas adsorption, can be used to provide results that can be correlated with the Hg intrusion results. d 孔、50%表面積 This is the pore diameter at which 50% of the free surface area exists.

[0100] #Total Fe (wt%) is preferably determined by dichromate titration, more preferably as shown in ASTM E246-10 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as titration after tin(II) chloride reduction, titration after titanium(III) chloride reduction, and inductively coupled plasma (ICP) spectroscopy, can provide results that can be correlated with those obtained by dichromate titration.

[0101] ##Metallic Fe (wt%) is preferably determined by iron(III) chloride titration, more preferably as shown in ISO 16878 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as bromine-methanol titration, can be used to provide results that can be correlated with those obtained by iron(III) chloride titration.

[0102] ### The metallization (%) is preferably determined by the ratio of metallic Fe to total Fe, each of which is preferably determined by the method described above.

[0103] #### Carbon (wt%) is preferably determined by infrared absorption after combustion in an induction furnace, and more preferably as shown in ISO 9556 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as various combustion and inert gas melting techniques, including those shown in ASTM E1019-18, can provide results that can be correlated with infrared absorption after combustion in an induction furnace.

[0104] #####Fe 2+ The (wt%) is preferably determined by titration, and more preferably as shown in ASTM D3872-05 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as Mössbauer spectroscopy and X-ray absorption spectroscopy, can be used to provide results that can be correlated with those obtained by titration.

[0105] $Fe 3+ (Weight %) is preferably total Fe (weight %), metallic Fe (weight %), Fe 2+ (weight %) and Fe 3+ It is determined by the material balance relationships between (weight %) values, or within these values. Specifically, Total Fe (weight %) = Metallic Fe (weight %) + Fe 2+ (Weight%)+Fe 3+ The equation (weight %) must be true by the law of conservation of mass, and therefore Fe 3+ (By weight %) is Fe 3+ (weight %) = Total Fe (weight %) - Metallic Fe (weight %) - Fe 2+ It can be calculated as a percentage (by weight).

[0106] $$SiO2 (wt%) is preferably determined by gravimetric methods, and more preferably as shown in ISO 2598-1 (the disclosures in this document are incorporated herein by reference in their entirety). It is recognized that other tests, such as reduced molybdosilicate spectrophotometrics and X-ray diffraction (XRD), can provide results that can be correlated with gravimetric methods. In certain methods, SiO2 wt% is not determined directly, but rather the Si concentration (including neutral and ionic species) is measured and SiO2 wt% is calculated based on the stoichiometry of SiO2. That is, it is assumed that the molar ratio of Si:O is 1:2.

[0107] The ferrite (weight %) is preferably determined by X-ray diffraction (XRD).

[0108] $$$$Wustite (FeO, wt%, XRD) is preferably determined by X-ray diffraction (XRD).

[0109] Goethite (FeOOH, wt%), XRD is preferably determined by X-ray diffraction (XRD).

[0110] +Cementite (Fe3C, wt%, XRD) is preferably determined by X-ray diffraction (XRD).

[0111] Furthermore, the characteristics shown in Table 4 may be present in embodiments in addition to, or instead of, the characteristics in Tables 1, 2, and / or 3. Larger and smaller values ​​of these characteristics may also be present in various embodiments.

[0112] Electrochemical cells, such as batteries, store electrochemical energy by generating a voltage difference between the positive and negative electrodes using the difference in electrochemical potential. If the electrodes are connected by a conductive element, this voltage difference generates an electric current. In a battery, the negative and positive electrodes are connected in parallel by external and internal conductive elements. Generally, the external element conducts electrons, and the internal element (electrolyte) conducts ions. Since charge imbalance between the negative and positive electrodes is unacceptable, these two flows must supply ions and electrons at the same rate. During operation, the electron current can be used to drive external devices. Rechargeable batteries can be recharged by applying an opposite voltage difference that drives the electron and ion currents to flow in the opposite direction to the discharged battery.

[0113] Generally, electrodes and electrode materials that are low-cost and easy to manufacture are desired, especially for long-term storage applications. Production and / or manufacturing processes can be evaluated and selected based on multiple criteria, including capital costs, material supply capacity, labor costs, number of unit operations, number of material transfers, number of material handling steps, required energy input, and the amount of waste and / or by-products generated.

[0114] Electrochemical cells, such as batteries, store electrochemical energy by generating a voltage difference between the positive and negative electrodes using the difference in electrochemical potential. When the electrodes are connected by a conductive element, this voltage difference generates an electric current. In a battery, the negative and positive electrodes are connected in parallel by external and internal conductive elements. Generally, the external element conducts electrons, and the internal element (electrolyte) conducts ions. Since charge imbalance is not permitted between the negative and positive electrodes, these two flows must supply ions and electrons at the same rate. During operation, the electron current can be used to drive external devices. Rechargeable batteries can be recharged by applying an opposite voltage difference that drives the electron and ion currents to flow in the opposite direction to the discharged battery.

[0115] Iron is an ideal electrode material due to its low cost, very high yield, recyclability, and high theoretical and practical energy storage capacity in terms of energy stored per unit mass of material. The low material cost and high energy storage capacity result in a large amount of energy stored per unit of raw material. These factors, particularly the cost per unit of stored energy and yield, are crucial for long-term grid-scale energy storage applications that are cost-sensitive and require the storage of very large amounts of energy. Iron is also inherently electrically conductive, which can simplify the problems associated with charge uptake and downtake in battery electrode materials encountered in many battery systems.

[0116] A central issue in the design of all battery electrodes is enabling the transport of electrons and ions to and from the reaction site. Generally, this requires interconnected pores in the electrolyte for ion transport and a permeable, electrically conductive network. In the iron battery electrodes disclosed herein, porous iron microparticles provide pores filled with a caustic electrolyte. The permeable, electrically conductive network is provided by the iron material itself, which has conductive metallurgical junctions formed by thermomechanical treatment. Metallurgical junctions can occur through a combination of solid-phase diffusion by mechanically induced plasticity and bonding. In particular, iron forms far more discharge products than iron metal itself. Therefore, to accommodate the microscopic formation of large amounts of discharge products, iron electrodes generally need to have a large amount (>40%, more preferably) of microscopic porosity. Porous iron microparticle materials satisfy the requirements of being inherently conductive and having a larger amount of microporosity. The methods described herein describe how these materials are effectively bonded so that high-performance electrodes can be obtained at low cost.

[0117] The use of iron as a conductor is ideal for iron electrodes because it does not involve additional parts, assemblies, joints, or other design elements that add cost and complexity to the material; iron itself is the ideal conductor. The central problem with forming metallurgical joints between porous iron microparticle materials is that many of the techniques used to join these metals are either not well suited to joining porous materials, or they cause a densification of microporosity, or have other related problems. For example, arc welding results in evaporation of the porous iron material, sintering results in overall densification and the resulting loss of microporosity, and mechanical compaction at low temperatures can result in a decrease in electrical connectivity due to the densification of the material and lack of interdiffusion between particles. The problems associated with low-temperature mechanical compaction become more pronounced as the particle size of the microparticle material increases, because the material has a greater tendency to flow / relax compaction. High-temperature thermomechanical treatment is particularly suitable for joining porous iron microparticles for battery applications because stress concentration at the contact points between particles can localize deformation (and the resulting joint) while simultaneously creating a metallurgical joint. Local deformation avoids the loss of microporosity at points away from the contact points between particles.

[0118] Several forms of high-temperature thermomechanical processing are already in large-scale use, including uniaxial hot pressing, hot briquetting, and hot isostatic pressing.

[0119] Generally, high-temperature thermomechanical treatment involves simultaneously applying high temperature and pressure to a material in order to deform and / or integrate the material. In this context, high temperature and pressure are used to achieve metallurgical bonding between porous, fine-grained iron materials. For typical embodiments, the process conditions, along with the range of process parameters, are shown in Table 5 below. [Table 5]

[0120] Similarly, various materials can be used. These materials generally inherit their material composition and properties from the processing techniques used in their manufacture. For example, directly reduced iron materials have a porosity of 50-70% by volume within the particles and an iron content of ≥85% by weight. Higher purity is generally preferred for more consistent and higher-performance electrodes. Porous particulate iron materials have a moderately high specific surface area (>0.003 m²). 2 A value of / g is preferable, and a higher value is preferable to a certain extent. If the surface area is very high, the reactivity will be too high both during processing and use, and the specific surface area > 3m² 2 / g is too high. On the other hand, sponge iron used in powder metallurgy for automotive parts manufacturing has much higher purity but substantially lower porosity. Generally, electrode materials manufactured by the methods described herein can produce satisfactory performance when the total microporosity in the final manufactured part is >50%. The above porosity may be derived from the microporosity in particles supplied to a high-temperature thermomechanical process, or it may be obtained from a combination of microporosity in particles and microporosity resulting from bonding formation between particles.

[0121] Guidance on adjusting process parameters based on material input characteristics and process changes

[0122] Given the various mechanical properties achievable with porous iron particulate materials and the degree to which these properties can vary with thermomechanical treatment, those skilled in the art will understand that the pressure and temperature ranges described herein may need to be modified based on the specific material being used. Some guidance is provided herein to assist in process modifications. If the porous iron particulate material contains hardened phases or elements such as carbon, the required pressure may be higher than those described herein to overcome the increase in yield stress. The pressure roughly increases or decreases with the yield and / or press hardness of the material at the processing temperature. Similarly, the lower the porosity of the porous iron particulate material, the higher the stress may be required for integration.

[0123] Preferred compacted body morphology

[0124] The deformation required for sufficient interparticle bonding varies depending on the type of input material used. For materials input as relatively large particles (>1 mm), the microporosity generated by particle bonding may be negligible compared to the microporosity within the particles. This is the case, for example, with directly reduced iron materials. In this case, to maintain sufficient porosity within the material, the consolidation process may be controlled so that the volume reduction of pores is sufficiently low and the material maintains >50 volume percent of microporosity within the particles after the consolidation process. Initially, this can be calculated from basic volume conservation and the volumetric engineering strain applied to the material. Therefore, input materials with high initial porosity within the particles can accommodate large deformations while maintaining >50 volume percent of microporosity within the particles. In many cases, particles do not have sufficient initial porosity to warrant large bulk deformation. If excessive bulk deformation is undesirable, deformation may occur only at the contact points through appropriate adjustment of the process, as schematically shown in Figures 1(A), 1(B), and 1(C).

[0125] An extremely desirable inert atmosphere

[0126] In many cases, porous iron particulate matter can be insulating when handled as bulk particulate matter. It may be preferable to preheat the material in equipment designed to heat insulating material uniformly (a heated kiln or blender). Otherwise, porous iron particulate matter may be produced using a high-temperature method, or the material may be supplied to a compaction apparatus at an already high temperature. Such heating and supply equipment may contain a substantially non-oxidizing atmosphere.

[0127] In many cases, the high surface area of ​​porous iron particulate matter allows undesirable oxidation to occur when the material is exposed to oxygen or other oxidizing agents at high temperatures. Therefore, a non-oxidizing atmosphere (e.g., an inert or reducing atmosphere) may be preferable during any part of the process that occurs at high temperatures, and the manufactured parts are typically cooled to a temperature where the reaction is slow (e.g., below 100°C) before exposure to oxygen or other oxidizing agents. In some examples, passivation of the material by exposure to small amounts of oxygen before exposure to large amounts of oxygen occurs may be useful. It should be further noted that electrical connections between particles also function as thermal connections between particles. Therefore, the compacted material may be effectively convectively cooled from one side after manufacturing (e.g., by passing it under a fan), although one-sided convection is not a useful cooling technique for bulk particulate matter materials that are not in thermal communication with each other. Therefore, in some embodiments, the parts may be manufactured in an inert or reducing atmosphere, transferred to a belt after manufacturing, and cooled by convection while maintaining a substantially non-oxidizing atmosphere. Passivation may occur simultaneously with or after cooling. In some embodiments, the manufactured compacted body may be discharged at high temperatures into a storage room or other container filled with a substantially non-oxidizing atmosphere, cooled, and possibly passivated.

[0128] In some cases, preventing oxidation during or after high-temperature thermomechanical treatment may not be possible to the desired extent. In such cases, oxidation may be removed from these surfaces by suitable means after electrode formation. For example, in some embodiments, surface oxides formed during or after treatment may be electrochemically reduced within the battery system before or during the cycle. In some embodiments, surface oxides formed during or after treatment may be thermochemically reduced in a reducing gas stream before being incorporated into the battery system. In some embodiments, surface oxides may be chemically reduced by introducing a suitable reducing solution. Suitable acids for reducing iron surface oxides include solutions containing nitric acid, sulfuric acid, and acetic acid, which are used for etching or pickling steel.

[0129] High-temperature thermomechanical treatment may be carried out by appropriate application. Thus, in various embodiments, pressure and / or heat may be applied by one or more of the following processing techniques: hot isostatic pressing (HIP), uniaxial hot pressing, hot rolling and densification (which may be uniaxial or biaxial), hot briquetting (using rolling in some embodiments, and sometimes by uniaxial densification), or hot forging. Below, specific methods for producing geometric shapes suitable for use as battery electrodes will be discussed for each processing technique, with particular attention to electrodes suitable for long-term energy storage.

[0130] Using a hot isostatic press, large billets of material can be economically manufactured with precise densification levels by appropriately selecting the time-temperature-pressure schedule. The application of HIP differs in that, in this context, the goal is not complete or near-complete densification, but rather to integrate the material in an economical way. In some embodiments, the electrode shape is constructed in a can used for integrating the material, and the output of the HIP process yields a useful electrode. In some embodiments, a very large can is manufactured to reduce the cost of can manufacturing and cut from the billet obtained from the HIP process. The above temperature and pressure conditions can be used as a starting point for tuning the HIP process to suit a given material and electrode application.

[0131] When low consolidation pressures are required, large billets can be manufactured using a uniaxial hot press. Often, the required consolidation pressure, as well as the required temperature, is much lower than that for typical hot press applications. Therefore, the unit cost of hot pressing can be substantially reduced compared to typical applications. In some embodiments, a steel hot press may be inserted, the material may be fed into the press by material measurement, and the material may be pressed automatically. This process may resemble uniaxial hot pressing in terms of the size of the articles manufactured, but may resemble hot briquetting in terms of the parts manufactured per unit time and the time scale required for pressing. In some embodiments, the particulate material may be consolidated quickly and in a very short time, and as a result, the hot uniaxial consolidation process is most similar to hot forging.

[0132] Integrated technology

[0133] Thermal spraying

[0134] Thermal spraying may be used to produce large billets from particles. The bonding, density, and other properties of the resulting compacted material can be advantageously controlled by controlling process parameters such as speed, temperature, and direction, as well as the adhesion rate of the sprayed particles. In one embodiment, porous particulate iron particles are sprayed onto a substrate. The substrate can function as a current collector or as structural reinforcement for the resulting billet. In another embodiment, bonding particles can be sprayed together with the porous particulate iron particles or onto a bed of prepared DRI particles to bond the porous particulate iron particles.

[0135] Porous iron particulate matter particles may be joined together using additive manufacturing methods such as DRI laser sintering or laser melting (e.g., direct metal laser sintering (DMLS)) to form or add large billets. In some embodiments, a layer-by-layer process may be used, in which case one or more layers of particulate material are deposited and laser energy is applied to the entire layer or a selected area within the layer. In some embodiments, one or more galvanometers, positioning systems, and / or optical components may be used to direct the laser energy to the desired area. In some embodiments, other directed energy application strategies, such as digital light processing (DLP) projection techniques, microwave radiation, resistance heating, and electric arc heating, may be used instead of or in conjunction with the laser. Such methods can also be used for localized modification of one or more areas of an existing billet.

[0136] Welding technology

[0137] In some embodiments, porous iron particulate matter particles may be joined or integrated using one or more welding techniques (for example, by forming metallurgical joints between the particles of porous iron particulate matter, thereby making the particles into a mechanically and / or electrically continuous billet). Such methods include AC resistance welding, DC resistance welding, arc welding, explosion welding, forge welding, high-frequency (HF) welding, capacitive discharge welding, friction stir welding, and other conventional fusion welding techniques. In some embodiments, filler materials and / or flux materials may be used, for example, to enhance the joint or reduce or eliminate the tendency to oxidize in the weld.

[0138] Ultrasonic compaction vibration, comprising ultrasonic vibration, may be used alone or in combination with other heating and stirring methods herein as one method for thermally or mechanically agitating porous iron particles. Vibration may also be used in combination with other pressing processes to assist with consistency, speed, bonding strength, or other aspects of the compaction process.

[0139] Manufacturing of larger or simpler compacted bodies, and their slicing or post-machining: In some embodiments, the formed billet may be larger than or otherwise different from the desired geometric shape of the electrode or its components, and the billet may be subsequently processed by sectioning, machining, assembly, or other methods to obtain a suitable intermediate or end-use shape. This can be advantageous in that it can achieve low cost and high yield when forming the billet by adjusting the shape of the billet to suit the compaction method used. Such billets may be formed using one or more suitable compaction methods. The initial shape may be similar to or substantially different from the desired shape. In some embodiments, the initial shape may include to some extent the desired geometric shape (e.g., a 2D profile extending in a third dimension) extending along one or more axes, and the desired shape may be obtained by cutting the billet into slices. In other embodiments, the billet may require only local machining or reshaping to achieve the desired shape. This sectioning or shaping may be achieved by using one or more cutting, splitting, milling, or grinding processes. Such processes include cutting by water jet, plasma, laser, oxygen-fueled torch, and / or mechanical sawing. The billet material may also be shredded, sheared, scraped, snapped, bent, or shaped into a favorable geometric form. The resulting geometric form may represent one or more complete electrodes or components of an electrode, one or more of which may be assembled with other components to form an electrode.

[0140] Cold compaction. In some embodiments, the above-described integration processes, particularly rolling compaction, isotropic pressing, and uniaxial pressing, may be carried out at room temperature or substantially lower than the temperatures typically used in a given compaction process in industry. Such low-temperature billet formation is advantageous in that it reduces or eliminates the complexity and cost associated with heating the material to high temperatures and the equipment required for high-temperature processing. This low-temperature processing can be achieved by appropriate adjustment of process parameters such as time or pressure, and by formulation of porous iron particles or other modifications. In some embodiments, the composition, microstructure, and / or shape of the iron particles may be formulated to facilitate billet formation at lower temperatures. In some embodiments, physical, chemical, or other surface treatments may be used to facilitate billet formation at lower temperatures.

[0141] As an alternative to cold bonding, cold extrusion can be used to form shapes designed to enhance electrode performance by increasing the usable surface area of ​​the electrodes. Cold extrusion can be used to produce 3D meandering blocks from ore slurry. The slurry passes through the DRI reactor as a block and is reduced to a high-surface-area iron block. The shape can be a sphere, a cylinder, or any 3D shape that flows freely within the reduction reactor. The surface area can be further increased by adding surface textures such as pores, depressions, and ribs. In some embodiments, additive materials that burn up at high temperatures during reduction, such as binders, may be used.

[0142] Alternatively, the above shape may be formed by reducing iron oxide to iron and then using cold extrusion.

[0143] Another method for creating complex 3D shapes with added porosity involves drying an iron ore slurry using techniques common in the ceramics industry, such as plaster casting or mold casting, and then curing it in a high-temperature oven. In other embodiments, such techniques can be used in combination with reduced iron.

[0144] Non-uniform compaction temperature

[0145] In some embodiments, one or more regions of the material may be at one or more different temperatures, potentially having larger areas of higher and lower temperatures at different points in shape and time. This non-uniform temperature profile can be used to modify the behavior and properties of porous iron materials in a way that is advantageous in promoting desirable bonding, porosity, deformation, or other important properties. In some embodiments, the material is hottest on the surface of a flat electrode, thereby producing maximum strength at the edges and only slight deformation in the interior. The resulting electrode exhibits a useful combination of high bending strength from deformation near the high-temperature surface, while maintaining porosity in the lower-temperature interior away from the surface.

[0146] Combinations of multiple billets, particle addition to existing billets. In some embodiments, the densification and joining methods can also be applied to the billets, or some combination of porous iron particles and their billets, including those described herein as methods for integrating porous iron particles. Such methods can be used, for example, to join one or more billets to another billet, or to join additional porous iron particles to an existing billet. Any such heating, pressing, welding, spraying, or other techniques may be used one or more times in various orders.

[0147] Shape of the electrode or billet

[0148] Any billet or electrode must have sufficient mechanical and electrical robustness to avoid damage throughout its entire lifecycle, including any manufacturing, assembly, transportation, operation, service provision, and disposal procedures. The geometric shape of the electrode or billet may be selected in a manner that promotes its robustness. In some embodiments, the dimensions, thickness, and aspect ratio of the billet or electrode may be selected so that its geometric shape is sufficiently robust against various forms of fracture or degradation.

[0149] Channeled electrode with enhanced performance characteristics

[0150] In general, for many battery electrodes, especially thick-format electrodes, ion transport can limit the electrode's rate capacity. In hot-compacted and pressed and sintered electrodes, particles deform to form a dense structure, resulting in reduced macroporosity for ion transport through the anode thickness. Furthermore, the resulting macroporosity may have high meandering and an unfavorable alignment with respect to the direction of ion transport. Therefore, there is a need for apparatus designs and processing methods to enhance ion transport through the electrode thickness. Moreover, in some hot-rolling processes for porous electrodes, it can be difficult to provide a surface for pressing the material against the electrode grip when low compaction is desired. Protruding features can mechanically engage the rollers and the material, allowing rolling to occur with less force. Textured or channeled electrodes with varying degrees of compaction and / or metallurgical bonding across the entire electrode area can usefully exhibit enhanced mechanical robustness and electrical conductivity.

[0151] Variable-thickness channels and other similar patterns of designed shapes within metallurgically bonded electrodes can be formed by various methods.

[0152] The tool for manufacturing the electrode may be patterned with multiple protruding features (spikes, cones, rods, etc.), which create macroporosities that extend through the electrode thickness by removing material during the pressing process. This tool may then be used to mechanically manufacture the electrode by pressing, rolling, or other methods. The electrode may be pressed for subsequent sintering, and the tool may remain on the electrode for at least part of the sintering process, or the tool may be used to press the electrode (in a hot or cold pressing operation) for subsequent use. In some embodiments, the area ratio and spacing of the protruding features may be optimally calculated to yield a compromise between rate capacity and area capacity that is best suited to the particular application. In some embodiments, a rolling and densification process may be used. The rolling and densification process may use high temperatures above 300°C to metallurgically bond the electrode material. The input material for electrode manufacturing may be iron or a derivative thereof. More specifically, the electrode material may be sponge iron, direct reduced iron, or any other similar highly porous metallic iron material. Conical protrusions may be used to ensure adequate material flow around the protrusions and to minimize tool wear. The projection angle may be selected to provide a surface to press into, or otherwise optimized. Figures 7, 8(A), and 8(B) show examples of tooling and pressing operations for forming channeled electrodes according to various embodiments.

[0153] Toothed rollers can also be used to create patterns with channels within electrodes. Figure 9 shows examples of toothed rollers that may be suitable for forming channeled electrodes according to various embodiments.

[0154] In a hot rolling press, the rollers may be textured to intentionally increase the density of the hot-compressed material in specific locations. This increased material density serves two purposes: (1) adding areas of higher strength and improving handling; and (2) adding areas of higher conductivity and providing a highway for electron flow. These features act as integrated / formed busbars. Steel busbars can then be welded directly to these areas to carry current out of the electrode. Figure 10(A) provides an overview of examples of channeled electrodes according to various embodiments. Figure 10(B) shows a cross-section of a portion of the channeled electrode example in Figure 10(A). Figure 11(A) shows an example of a textured roller, and Figure 11(B) shows an example of the operation of forming a channeled electrode according to various embodiments using two of the textured rollers in Figure 11(A). In a hot rolling press, the rollers may be textured to intentionally increase the density of the hot-compressed material in specific locations. This increased material density serves two purposes. In other words, areas of high strength are added to improve handling; and areas of high conductivity are added to provide a highway for electron flow. These feature areas can act as integrated / formed busbars. For example, steel busbars can then be welded directly to these areas to carry current out of the electrodes.

[0155] In the rolling and densification process, the electrodes may be separated into sheets by cutting or separating features incorporated into rollers, which periodically cut the sheets or provide features to a continuous sheet for later separation. The rollers may be densification rollers, and the applied pressure may be generated at least partially by the densification rollers. Figures 12(A) to 12(C) show side views of an example of a cutting or separating mechanism used to separate the sheets of formed electrodes. In Figures 12(A) to 12(C), the formed electrode sheets are fed between the rollers (downward in the direction shown in the figures). Figure 12(A) shows the formed electrode sheets being fed between the rollers for the first time. Figure 12(B) shows a cutting mechanism in which two rollers rotate in opposite directions and meet to cut the formed electrodes. Figure 12(C) shows the formed electrode sheets still being fed between the rollers, but the section below the rollers is now being cut.

[0156] In some embodiments, porous particulate iron material may be joined together to form sheets of electrically conductive material using hot rolling, densification, or hot briquetting with rollers. For example, Figure 2 shows an embodiment of hot rolling and densification in which mechanically and electrically connected material is produced. According to various embodiments, electrodes may be supplied to an electrochemical system without the application of external current collectors or filling of electrodes. The sheets may be patterned or cut during the rolling process either in a direction that creates a geometry desirable for incorporation into battery electrodes, or to facilitate the subsequent formation of the above geometry. High-density briquettes are produced from porous particulate iron, particularly DRI, using hot rolling and densification techniques such as hot briquetting. The process of hot briquetting DRI is called the hot briquetized iron (HBI) process. The HBI process aims to make the DRI as high-density as possible (i.e., increase its density) in order to reduce the amount of microporosity and thereby reduce the reactivity of the material for safer loading and handling. To produce battery materials, it can be useful to reverse the idea of ​​increasing the density of HBI: such a briquetting process minimizes the densification of the material while obtaining strong conductive metallurgical bonds between the materials. Such a modification of the hot briquetting iron process has several significant advantages. Firstly, in the case of an in-line briquetting unit in a DRI plant, the material is already at a high temperature and in a reducing / protective atmosphere. This essentially eliminates the costs associated with these aspects of thermomechanical treatment. Secondly, the process is continuous and high-capacity (some HBI plants produce >1 million tons of HBI per year). Thirdly, the briquetting process is inexpensive, adding only a small amount to the cost of steelmaking inputs. Finally, hot briquetting machines already incorporate a cutting mechanism into the process to convert continuous sheets of briquetting material into sets of separate electrodes. To avoid the collapse of microporosity, the briquetting process generally occurs under different operating conditions than those typically applied to the production of high-density HBI products. The parameters are specific to the geometric shape of the electrode being fabricated and the material being compacted, but may also be determined empirically.Firstly, the DRI temperature during pressing may be reduced to limit the softening of the iron and maintain internal porosity. Secondly, the pressure applied to the rolls may be reduced and may vary up to a certain limit. Thirdly, the rolling speed may be reduced to increase the time the iron is under pressure and enhance its ability to form interparticle bonds. Fourthly, the gap between the rolls may be controlled to a higher tolerance to ensure uniform thickness in the compacted electrode.

[0157] Material handling and modification before integration of iron electrodes

[0158] There are several challenges in handling materials for the fabrication of metallurgically bonded iron electrodes. First, the materials must be blended and maintained throughout the supply process. Second, the weight and volume of the materials must be controlled to minimize heterogeneity within and between electrodes. Third, the materials must be properly treated and prepared for bonding via any applicable heating and any desired chemical reactions. Fourth, any other applicable materials that need to be incorporated into the electrodes must be supplied to appropriate equipment for bonding particulate materials.

[0159] Surface preparation: The surface of the material may optionally be prepared by the following surface preparation methods. Surface preparation may be carried out at numerous points during material processing and handling. In order to achieve the desired bonding between iron particles, it may be necessary to remove impurities or harmful phases from the surface that interfere with, delay, or prevent metallic bonding. Of particular importance are oxide coatings, which are often associated with DRI production, and these inorganic compounds are designed to prevent adhesion during DRI production and therefore interfere with bonding in subsequent operations. Commonly used techniques such as solvent cleaning, acid etching, and sand / shot blasting may be used before heating and integration.

[0160] Heating: In many integration and / or metallurgical joining processes, it may be desirable or necessary to heat the materials before the joining or integration step itself. For example, achieving a metallurgical joint by a hot consolidation process often requires temperatures >400°C. Similarly, in many welding processes (e.g., resistance welding), preheating the material enhances the consistency and quality of the joint. Iron materials can be heated in numerous ways. In some cases, porous iron materials may be heated by radiation and / or electric heaters, by inductive bonding to the porous iron material itself, or by being placed in the presence of a combustion gas atmosphere. Porous iron materials may also self-heat by introducing oxygen into the process atmosphere and reacting with the porous iron material. Mechanical actions such as crushing, rotating, stirring, and ultrasonic stirring can also be used as means of heating, whether or not other purposes are achieved by using these actions. Materials may be preheated and stored in insulated storage containers in bulk to maintain a moisture-free state and eliminate the need for rapid heating. Heating may be carried out in a continuous furnace such as a rotary hearth furnace, rotary kiln, linear hearth furnace, tunnel furnace, or linear grate furnace. In some cases, the heating atmosphere may be designed to achieve a chemical change in the porous iron material.

[0161] Particle Size Control and Blending: Porous particulate iron materials may be reduced in size, classified according to size, and blended to achieve optimal particle properties for the formation of metallurgically bonded electrodes. Particle size reduction may be achieved through any one of the techniques known in the art for reducing the particle size of particulate materials, including but not limited to high-pressure grinding rolls, jaw crushing, gyratory milling, and / or hammer milling. In some cases, porous particulate iron materials may be combined from two separate sources or manufacturing processes to produce an optimal blend or particle size distribution. In some cases, a single input material may be divided into various parts, which may undergo different size reduction and classification processes to achieve the desired size distribution. A suitable size distribution can be ensured by the use of sieving, air classifiers, or other particle sizing and classification techniques known in the art for handling particulate metal materials. Such sizing operations may be operated in-line and continuously with the material processing, or in separate batches. Blending or homogenization may be performed to ensure product quality and homogenization. Blending may be carried out through various blending and splitting techniques suitable for the particle size used. For example, finer particulate materials can be blended in a double-cone or V-type blender, while coarser particulate materials can be better blended through a series of ruffle and mixing steps.

[0162] Weighing, Conveying, and Dosing: Porous particulate iron material may be conveyed, weighed, and dosed using techniques appropriate to the applicable particle size and mass processing volume. In some embodiments, screw conveyors or other volumetric techniques can be used to provide material at a uniform volumetric flow rate. In some embodiments, vibrating gravimetric feeders or loss-in-weight feeders can be used to provide a constant feed rate per unit time. In some examples, volumetric and gravimetric conveying may be combined at various points in the material feeding process. When flow rate control is not critical, conveying using pneumatic, magnetic, or slurry may be utilized between different processing units. Blending may be performed at the beginning of conveying, at the end of conveying, or periodically throughout the material transport to ensure material homogeneity.

[0163] Processing and upgrading of materials during transport: In some cases, dust associated with the material may interfere with bonding during subsequent processing. In such cases, the porous particulate iron material may be dusted. In some embodiments, dusting may be carried out by jet blasting air over the particles. In some embodiments, dusting may be carried out by supplying the material through a chamber at a sufficient air velocity to allow for the transport and removal of the generated dust, for example, a vibrating surface may mechanically remove the dust from the surface by agitation, and remove it from certain porous iron materials.

[0164] Customization of material shape and properties in integrated processes: In some cases, materials used for metallurgical bonding to iron electrodes may have shapes different from the spherical shapes commonly used in direct reduction processes. In such cases, more suitable shapes can be created by extrusion, modification of pelletizing techniques, pressing, or other suitable processes. Cylinders, hexagons, octagons, or other shapes may be used in the manufacture of porous particulate materials.

[0165] Use of particle size reduction technology in the manufacture of iron electrodes

[0166] Metallurgical joining of DRI can be difficult because the pellets are often coated to prevent sticking during the various heating, handling, and reduction processes carried out to manufacture DRI. This joining process can also be achieved by increasing and applying heat, temperature, pressure, or other appropriate process variables—essentially, increasing the degree of melting, deformation, or densification and microstructural modification ultimately results in a satisfactory joint. However, microstructural modification by welding usually leads to a decrease in electrochemical performance. This is due to densification and the resulting loss of microporosity and specific surface area necessary for electrode performance.

[0167] The inventors have found that some particle size reduction processes result in the preservation of most of the microporosity in porous iron fine particle materials. Reducing the particle size of the material exposes fresh surface areas not covered by the anti-adhesion coating used in the previous processing step to prevent material adhesion. These fresh surface areas can then be metallurgically bonded relatively easily. Very large particle size reductions are not necessary to have a significant impact on the enhancement of adhesion. As a very rough approximation, consider spherical particles where 75% of the surface area is uncoated. Reducing the particle size to one-quarter results in 93.75% of the surface area being uncoated. Therefore, even a slight reduction in particle size can lead to significant changes in material behavior during metallurgical bonding.

[0168] The use of necessary particle size reduction techniques not only usefully enhances the quality of electrode adhesion and electrical connection, but also ensures that electrodes are less susceptible to fluctuations in upstream processes from suppliers, and the relaxation of regulations and constraints on the type and amount of coating broadens the range of potential suppliers that can supply materials for electrodes. Thus, the use of reduced particle size is useful in enhancing process robustness, reducing electrode variability, and increasing the flexibility of material production suppliers.

[0169] Particle size reduction techniques include jaw crushing, hammer milling, gyratory milling, and grinding using parallel plate grinders.

[0170] Metallurgical joining techniques may include welding, sintering, or pressing, or combinations of these with other techniques, and combinations between the listed techniques. Welding may include DC resistance welding and AC high-frequency resistance welding. Sintering may include sintering under low pressure and pressing before sintering. Pressing may include hot or cold pressing. Pressing may include the application of pressure along one or more axes.

[0171] Use of a wide or engineered size distribution for iron electrode manufacturing

[0172] Several factors motivate the use of a designed size distribution in iron electrodes fabricated from porous particulate materials. Firstly, battery electrodes require active material to maintain an electrical connection with the current collector so that the electrodes can pass through the external circuit. Electrical insulation of the active material is a major form of capacity loss in many battery systems. This is particularly important in metal electrode systems where the active material often acts as its own current collector through the thickness of the electrode. Therefore, a system or method that ensures increased contact or increased robustness of electrical contact between active materials in a metal electrode is useful in enhancing the robustness of the battery electrode in terms of mishandling and / or active material degradation. Secondly, compression and / or compaction of porous metallic materials is one method of producing electrically connected, highly porous materials for battery electrodes. However, such compaction processes are inherently limited in that porosity is desirable for battery electrodes, and compaction processes often lead to mechanical degradation due to densification or plastic deformation and rearrangement of the particles being compacted. At the same time, battery electrodes need to be mechanically robust to enable handling, installation in assemblies, and maintaining excellent performance and connectivity throughout their lifespan. While mechanical robustness increases with increasing compaction, battery performance often decreases with increasing compaction. These two desirable characteristics for a battery directly conflict in electrode manufacturing processes using compaction. Therefore, methods and / or systems to avoid this technical conflict are extremely useful in the manufacture of compressed metal electrodes.

[0173] Broad and / or designed particle size distributions, including multimodal packing, can often increase contact per unit volume within the particle packing and increase the packing density of the material contained within the packing compared to narrower particle size distributions. Therefore, broad and designed particle size distributions are useful for designing the robustness of particles in contact with a compression electrode (where the active material is also a conductive phase, simultaneously increasing the packing density). Higher packing density leads to lower thickness and a lower overall system cost (e.g., due to less electrolyte required in the cell).

[0174] A problem induced by broad and / or designed particle packing is that smaller particles can rattle around in the spaces between larger particles. The volume fraction of such rattling particles is strongly related to the particle size distribution, shape, and packing method of the material, suggesting that broad and designed packing can lead to a lack of reproducibility in electrode characteristics from batch to batch and from run to run. However, the spaces in which these particles move are often very small, usually less than 1% of the particle diameter.

[0175] Therefore, a combination of a broad and / or designed particle size distribution and an electrode compaction method capable of achieving >1% uniaxial plastic deformation can significantly enhance electrode reproducibility and performance. By increasing density by a small amount (approximately 1%), the plastic deformation can lead to a substantial increase in the number and weight fraction of interconnected active materials, greatly increasing the robustness of the connections between active materials. For iron electrode materials made from materials with high internal porosity (e.g., iron sponge powder), this deformation can be achieved by applying very large forces (approximately 0.5–50 MPa) near room temperature, or by hot compaction of iron at relatively low pressures (approximately 0.1–10 MPa) but considerably high temperatures (>400°C and <1200°C). Naturally, a continuum of temperature and pressure combinations exists between these two extremes. Compaction techniques other than uniaxial compaction are possible.

[0176] It has been further discovered that when a broad and / or designed particle size distribution is used as the feedstock for the compaction process, the mechanical robustness of the resulting electrode material is far greater at the same degree of compaction (e.g., the same applied pressure and / or the same densification uniaxial strain).

[0177] Therefore, the use of broad and / or designed particle size distributions is useful for 1) generating a more robust conductive network between particles, 2) increasing packing density and reducing electrode thickness and system cost, and 3) enhancing the mechanical robustness of the resulting product. Figures 3(A) and 3(B) illustrate an example of comparison between unimodal packing shown in Figure 3(A) and bimodal packing shown in Figure 3(B), showing that bimodal packing has a different particle size distribution, with smaller particles filling the gaps between larger particles.

[0178] Some non-limiting considerations regarding the size ranges and manufacturing methods associated with various forms of DRI are given below. A key consideration is to maintain the microporosity of sponge iron while reducing particle size. These particle size reduction techniques have been shown to reduce particle size while substantially maintaining the internal microporosity of sponge iron. As one non-limiting example, DRI may be in the form of whole pellet DRI, e.g., pellets of about 6 mm to 20 mm formed from a shaft furnace. Other processes may have different preferred size ranges. For example, some DR processes, such as fluidized bed processes, inherently produce smaller DRI particles. As one non-limiting example, a fluidized bed may be used to obtain particles having an exclusive size of less than 6 mm. As another non-limiting example, DRI may also be in the form of crushed DRI, which is usually less than half the size of whole pellet DRI (e.g., about 3 mm to about 10 mm), and often at least one-third to one-fifth (e.g., 1 mm to 6 mm). As an unspecified example, such DRI may be formed by methods such as jaw crushers, gyratory crushers, high-pressure grinding rolls, and / or low-energy hammer mills. In some cases, the particle size of the DRI may be reduced by non-contact or limited-contact methods, such as spinning the DRI at a speed fast enough to break it down. As an unspecified example, the DRI may be in the form of finely crushed DRI or pulverized DRI, such as having a size of about 0.1 mm to about 2 mm. As an unspecified example, such DRI may be produced using higher-energy hammer mills, vertical grinding mills, and / or other finer grinding processes. As another unspecified example, other forms of sponge iron may also be used, such as sponge iron produced for the powder metallurgy industry by the Höganäs sponge iron production method, for example. Some specific details of the designed size distribution embodiment include whole pellet DRI mixed with crushed DRI and / or DRI fine powder, where the crushed DRI is one-third to one-seventh the size of the whole pellet DRI.Some specific details of the designed size distribution embodiment include whole pellet DRI mixed with crushed DRI and / or DRI fine powder, where DRI fine powder is waste product from DR facilities that could not proceed to electric arc furnaces. Some specific details of the designed size distribution embodiment include whole pellet DRI from shaft furnaces mixed with much finer-sized fluidized bed DRI. Some specific details of the designed size distribution embodiment include crushed DRI achieving different particle size distributions by incorporating DRI crushed by different processes. Some specific details of the designed size distribution embodiment include crushing processes, where the crushing process is designed to have an essentially broad size distribution.

[0179] In some embodiments, a target electrode thickness may be desirable. In such embodiments, the particle size may be selected such that the particle size is much smaller than the total thickness of the electrode, or the particles form an integer number of layers in the thickness direction of the electrode. This is shown in Figure 4, which illustrates desirable (horizontal solid line) and undesirable (horizontal dotted line) anode thicknesses for integer increments of layers of porous iron particulate matter (e.g., DRI) particles. To ensure consistent packing within the anode, it may be beneficial to adjust the relationship between the anode thickness and the particle diameter of the porous iron particulate matter. Furthermore, adding a certain proportion of crushed porous iron particulate matter mediates this effect by reducing the gradual increase in the desired thickness regardless of the overall pellet diameter. Figure 4 shows examples of desirable (horizontal lines 2 and 4) and undesirable (dotted lines 1 and 3) anode thicknesses for integer increments of layers of DRI particles. To ensure consistent packing within the anode, it may be beneficial to adjust the relationship between the anode thickness and the DRI particle diameter. Furthermore, adding a certain proportion of crushed DRI mediates this effect by reducing the gradual increase in thickness, regardless of the whole pellet diameter.

[0180] In certain embodiments, the iron electrode material and iron electrode disclosed herein can be used as a negative electrode in an alkaline electrochemical cell or Fe-air cell such as Fe-Ni or Fe-MnO2; other positive electrodes known to those skilled in the art may be paired with the iron (negative) electrode.

[0181] Reheating and controlled cooling of the DRI to achieve phase separation

[0182] DRI and other porous particulate iron materials represent inexpensive forms of iron for use in iron anodes of batteries, but DRI and other porous particulate iron materials often contain large amounts of iron carbide (often called cementite). Cementite and iron exhibit complex electrochemical behavior when paired as galvanic pairs, and as a result, it has been found that fabricating steel iron anodes from both iron and cementite starting materials is difficult. However, electrodes with similar amounts of graphite can be easier to fabricate due to the simpler reaction pathway. Such low-cementite electrodes can actually be more high-performance.

[0183] The inventors have discovered that higher-performance iron electrodes containing carbon can be designed using the metastability of iron carbide. More specifically, the performance of porous iron microparticle material containing cementite can be improved by heating it to a temperature at which the iron carbide decomposes to produce iron and graphite. The general requirement for heating is to maintain the material at a sufficiently high temperature for the metastable iron carbide phase to convert into iron and graphite. The kinetics of this decomposition reaction are complex but have been well studied in the steelmaking field. The microstructure length scale of the iron and graphite phases can be manipulated by manipulating temperature and time. Generally, the phase separation length scale may be a function of the battery electrode application, with lower temperatures promoting finer phase separation and higher temperatures promoting coarser microstructure. Generally, the processing temperature should be from about 300°C to around 727°C, the iron-carbon eutectoid temperature. Above this temperature, a considerable amount of carbon becomes soluble in iron, thereby limiting the amount of cementite that can be phase-separated. The preferred temperature range is 500 to 650°C, depending on the material used.

[0184] To separate cementite in porous iron particulate material without the need for reheating, or to reduce the time and energy required to reheat the material to the phase separation temperature, the porous iron particulate material can be kept at a high temperature after being discharged from the reduction furnace. This process is sometimes called "hot discharge." The concepts of hot discharge and reheating can be combined: the porous iron particulate material can be cooled to an intermediate temperature, reheated, and held at the reheating temperature to achieve phase separation. The cooling profile of the process may be controlled to control the microstructural properties of the remaining cementite.

[0185] Method for purifying carbon from iron electrodes

[0186] In general terms, reducing impurity levels in electrodes for secondary batteries is often crucial for improving electrode performance, but this generally involves costs, such as additional processing. Inventions that offer low-cost methods for purifying electrodes are important for many types of electrodes. In some embodiments, having low levels of carbon in iron anodes for secondary storage applications can be advantageous. This is for reasons such as electrochemical or cell performance, or manufacturability, such as the ability to integrate and bond the DRI with the anode by hot compaction. The final carbon content of the DRI may vary depending on the input materials, and it would be desirable to be able to reduce the carbon level in the DRI through manipulation of processing parameters and / or additional processes.

[0187] The carbon content of iron materials can be altered using chemical reactions of porous iron particulate materials accompanied by a gaseous atmosphere. Some of these are described below. These reactions may occur through reduction processes, selective changes in the processing atmosphere during sintering processes, or as separate, dedicated chemical processing processes.

[0188] Use of trace amounts of oxygen to reduce the carbon content of porous iron particulate materials: One possible method to reduce the carbon level of porous iron particulate materials is to deliberately expose sponge iron to an oxygen-containing atmosphere while it is at a high temperature, for example, by introducing trace amounts of oxygen into the atmosphere surrounding the DRI. The purpose is to oxidize the carbon in the sponge iron so that carbon is removed from the sponge iron material. The reaction that occurs is either C + O2 → CO2 or 2C + O2 → CO. According to the Ellingham diagram in Figure 5, the temperature at which these reactions spontaneously begin is approximately 700°C (depending on the purity of the atmosphere). The free energies of the oxidation of carbon and iron cross around this temperature (approximately 700°C), indicating that carbon can reduce iron as long as the carbon-containing gaseous byproducts are blown away as the reduction reaction proceeds. The reaction takes the form of: Fe3O4 + 4C → 3Fe + 4CO (or, depending on the temperature, Fe3O4 + 2C → 3Fe + 2CO2; similar other reduction reactions exist for other iron oxides). This reaction produces either CO2 or CO as a gaseous byproduct, which must be blown away for the reduction reaction to continue.

[0189] Use of oxygen in DRI for carbon removal in porous iron particulate matter: If the temperature is appropriately selected, carbon can reduce iron oxide even when both are in a solid state. Generally, this occurs at temperatures above about 700°C, at which point the oxidation of carbon begins to become thermodynamically favorable compared to the oxidation of iron, resulting in a reaction of the form FeO + CFe + COg or 2FeO + CFe + CO2,g. This results in the removal of carbon impurities from porous iron particulate matter and the formation of more metallic iron instead of iron oxide, both of which are desirable from the standpoint of electrochemical behavior. A flow of an inert gas such as argon or nitrogen is necessary to ensure the reduction reaction proceeds correctly. The amount of flow can be selected based on the amount of gaseous product that needs to be removed as the reduction process progresses. Using oxygen already present in the porous iron particulate matter is advantageous in that the reaction is self-limiting and therefore easily controllable, without the need to strictly control the total oxygen content of the atmosphere. Since oxygen is not introduced, undesirable oxidation of iron is essentially avoided.

[0190] The preferred temperature range for this method of removing carbon from iron may be selected such that the solubility of carbon in iron is high, and therefore the dissolution rates of Fe3C and graphite are rapid (i.e., above approximately 723°C for Fe-C eutectoid). The upper limit of the temperature range is limited by heating costs, densification, and the adhesion of porous iron particles in the material supply that can occur at high temperatures. Therefore, temperatures that are not high enough to allow the above phenomena are desirable. Generally, the optimal operating temperature for decarburization of iron by oxides of the iron itself is approximately 700°C to approximately 900°C.

[0191] In some embodiments, sponge iron may be used directly from a DRI manufacturing plant, utilizing the latent heat trapped in the material. In such cases, additional inert gas supply and heating may be used to adjust the temperature and atmosphere of the material to enable decarburization.

[0192] The iron-carbon phase diagram is shown in Figure 6. The rate-limiting step in the FeO-C reduction reaction below Fe-C eutectoid at approximately 723°C is the dissolution and diffusion of carbon in the iron, such that carbon reaches and reduces adjacent oxides. To allow this reduction to proceed more rapidly, the material must be heated higher than at eutectoid, where the solubility of carbon in iron increases by approximately 40 times, thereby allowing the diffusion of carbon into oxides in sponge iron and the resulting reduction to proceed much faster.

[0193] Depending on the use of a low-oxidizing, chemically active gas to promote decarburization without oxidizing iron, it can be difficult to achieve sufficient decarburization of sponge iron without oxidation. In such situations, a third method for achieving decarburization is to add a chemically active gas to the atmosphere holding the sponge iron to remove carbon. In some cases, this is preferable because it has a lower tendency to oxidize iron than pure iron. In some embodiments, hydrogen can be used to remove carbon by the following form of reaction: Cs + 2H2,g → CH4,g (this is effective for both cementite and graphitic carbon). The kinetics and thermodynamics of this reaction are most effective at intermediate temperatures between 300 and 800°C, and the decarburization reaction is stoichiometrically limited at high temperatures (>800°C) and kinetically slow at low temperatures (<300°C). In some embodiments, carbon dioxide can be used to decarburize sponge iron at high temperatures (typically above 700°C). The temperature and partial pressure at which CO undergoes decarburization have been well studied in steelmaking and are governed by the Boudouard reaction: CO2,g + Cs ↔ 2COg. The addition of CO2 advances this reaction to the right, forming CO through the oxidation of carbon. Since CO2 has lower oxidative activity than oxygen, it usually limits the amount of iron oxidation that occurs. In some embodiments, water can be used as the decarburization gas to obtain a reaction of the form Cs + H2Og → COg + H2,g. Water is a kinetically more effective decarburizing agent than hydrogen, and its reaction with carbon produces a reducing gas that can limit or prevent iron oxidation, and in some cases, can lead to the reduction of iron oxide. Water can be added as an effective decarburizing agent in a temperature range similar to that used for hydrogen. The concentration of water may be controlled by bubbling the gas into a water column at a controlled temperature, thereby controlling the dew point.

[0194] The inventors have found that some forms of carbon present in DRI exhibit faster decarburization rates than other forms of carbon. In some cases, DRI with a high graphitic carbon content may decarburize faster than DRI with nearly the same total carbon content but a higher cementite carbon content. Therefore, to minimize the amount of gas, time, and temperature required for processing, DRI with a high graphitic carbon content can typically be used as input to the decarburization process. Decarburization reactions that can proceed more easily to completion (or where it is reasonably predictable that the reaction will proceed to completion) exhibit more stable product properties and uniformity. Uniformity of material properties between and within powder particles is a highly advantageous property for battery active materials, and a uniform starting composition prevents current concentration and accelerated degradation at specific points in the electrode. In some embodiments, the decarburized material is included in metallurgically connected electrodes. In some embodiments, the decarburized material is included in electrodes that are not metallurgically connected, but may be included in a design having, for example, compressed active material between two current collectors.

[0195] In some embodiments, chemical reactions may be controlled using a combination of process gases. For example, H2 / H2O and CO / CO2 mixtures may be used for controlled decarburization of porous iron particulate materials. Such mixtures can set the oxygen potential of the process atmosphere so that, for example, oxygen can oxidize the carbon present in the iron without oxidizing the iron itself. The composition of such process gases may be calculated from thermodynamic data or determined empirically.

[0196] Decarburization may be carried out in various material processing devices such as kilns, tunnel furnaces, pusher furnaces, or rotary hearth furnaces.

[0197] Post-treatment of metallurgically bonded electrodes:

[0198] Following bonding and decarburization, the formed electrodes may be subjected to a series of processes including (1) rapid cooling, (2) cutting, (3) surface cleaning, and (4) application of a protective layer.

[0199] Various techniques can be applied to the rapid cooling of compacted electrodes. Rapid cooling is preferable to minimize the risk of re-oxidation and phase transformation that may occur during cooling. In some embodiments, this can be carried out by blasting cooling air or an inert gas, in which case the flow of gaseous species is sufficient in volume and velocity to enhance the heat transfer of the gas from the compacted electrode: the gas can be recycled via a heat exchanger or other means as needed, and the heat extracted from the compacted anode can be reused. Other embodiments include liquid cooling, such as spraying or immersion in a tank; continuous operation requires transport in and out of the liquid cooling area by means such as gravity incline, conveyor belt, or other commonly used methods. The liquid should be selected to enhance cooling and prevent oxidation of the electrode either by chemical incompatibility or by exceeding the oxidation reaction rate; liquids such as water, oil, nitrogen, or battery electrolytes can be used alone or in combination. In some embodiments, the coolant can also function as a protective coating.

[0200] After cooling, it may be necessary to adjust the electrode dimensions to conform to the battery's tolerances.

[0201] Surface cleaning of the formed electrodes may be necessary for removing compaction residue and subsequent processes. Commonly used techniques such as solvent washing, acid etching, and sand / shot blasting may be used before heating and integration.

[0202] The final step in anode processing is to coat the electrodes with a protective layer to prevent re-oxidation of the electrodes during transport, storage, handling, and battery assembly. In some embodiments, the coating may consist of forming a thin layer of iron oxide (also known as passivation) in a controlled, oxidizing atmosphere. Other embodiments include spraying a rust inhibitor or a liquid compatible with the electrical electrolyte onto the compacted anode, or immersing the anode. Still other embodiments include applying a sealing film or casing under vacuum.

[0203] Handling and automation of handling

[0204] Integrated porous microparticle iron electrodes, due to their mechanical properties, tend to have limited strength and increased mass and bulk, depending on the carbon content and integration process. This strength limitation means that these materials are difficult to handle, potentially requiring new features, processes, and mechanisms for handling battery electrodes. Means can be used to enhance the strength and handling of the electrodes, such as a material backing bonded to one or both sides of the electrode. The backing may be a permeable iron-containing material that secondarily acts as a conductive substrate. The backing material may be in the center of the electrode, with the porous microparticle iron material integrated on both sides. There may be areas of the integrated electrode that are densely packed and specially manufactured, processed to increase strength at load-bearing locations, providing increased strength and conductivity and facilitating current flow. Protective frames may be applied to one or more edges of the electrode, which may serve to increase handling strength in addition to providing locations for electrical connections. The electrode itself or these protective frames may have features that allow the electrode to be fixed, positioned, restrained, or suspended within an electrochemical assembly. These features can be manifested by holes, grooves, tracks, and shelves, and may allow the electrodes to contact only their mechanical support and current conduction paths via a protective frame, rather than the material itself derived from the DRI. The electrode design may include specific features that allow the electrodes to be densely and tightly packed in a transport container that is later returned to the manufacturing site for reuse. Electrode integration may be carried out at the site of reduction or decarburization of the material, and the electrodes may be cooled and passivated by immersion in the electrolyte itself in a container that serves as liquid containment for the electrochemical device.

[0205] A method for separating iron electrode units that have been metallurgically joined.

[0206] There are several challenges in processing thick or brittle electrodes. This is because such electrodes cannot be densely packaged by celluloid or other similar techniques (such as those used in lithium-ion batteries) due to bending or other reasons. Therefore, thick or brittle electrodes must be cut or shaped to the desired size and form. Such a process should produce electrodes of consistent shape and weight. In continuous processing, difficulties arise because the brittle material must be cut and shaped without damaging the rest of the electrode. Such a cutting process becomes even more difficult when the brittle electrode is made from metal, particularly metallurgically bonded metal particles such as iron. Such metallurgically bonded electrodes tend to be made from microscopically hard and heat-resistant materials, but can be macroscopically brittle, for example, due to the size of the contact points between particles being substantially smaller than the flow support, and the resulting stress concentration at the contact points. The microstructure of metallurgically bonded metal electrodes tends to be highly engineered to achieve the appropriate combination of porosity, surface area, and mechanical robustness for a given application. To minimize material loss or underutilization, a cutting method that preserves this designed microstructure with as many electrodes as possible is desirable.

[0207] System Architecture: In some cases, metallurgically joined electrodes may be manufactured in such a manner that they are formed to the desired shape and size during the joining operation, thus eliminating the need for further separation. In some cases, the manufacturing of individual electrodes may be carried out via any number of incorporated cutting, stress concentration, or other operations during the joining operation itself, such as stress concentration features contained in rollers used for the hot briquetting of direct reduced iron. In some cases, electrodes may be formed continuously and separated at a later stage of the process. If electrodes are formed continuously, the electrodes can be made to the desired size by cutting or other separation operations positioned along the electrode path. Separation operations may be stationary or may move in series with the electrodes using infrastructure such as a cam system.

[0208] Separation Mechanisms: In some cases, metallurgically joined iron electrodes may be cut or separated by any method common for cutting metals and other materials, especially brittle materials, including, but not limited to, shearing or other pressing actions, abrasive saws, diamond saws, chainsaws or other rotary cutting tools, water jets, bead blast streams, torches, lasers, or by scraping and snapping. In some cases, these cutting or separation methods may be used in combination, for example, scraping the electrodes with a rotary cutter followed by a snapping mechanism. In some cases, the electrodes may be separated by the use of a high-speed fluid, such as an air knife or oxygen knife, designed to achieve specific mechanical and / or thermal conditions on the electrodes. In some cases, the electrodes may be designed with a thermal profile favorable for cutting or separation by means of introducing oxygen to the electrodes, including but not limited to this method. In some cases, oxygen may be introduced into the cutting process to induce a local heating reaction where the reaction between the metal and oxygen of the electrodes produces heating. In some cases, oxygen introduction or other heat sources may be used to induce a thermal gradient and local softening of the electrode at points where separation usually occurs, for example, by cracking, melting, or a combination thereof.

[0209] Strengthening: In some cases, the cutting mechanism can be strengthened, which can occur through thermal or mechanical means. In some cases, the strengthening process may be included before, during, or after cutting.

[0210] System architecture of a hot compression anode manufacturing equipment

[0211] Hot-compressed electrodes can be manufactured at a very low cost and in high-capacity equipment. This is especially true when the equipment is integrated into a DRI manufacturing facility. TDRI can be moved directly from the DRI furnace to the hot-compression unit. This interface is very similar to the DRI furnace-HBI interface (where high-temperature material flows directly from the furnace to hot briquetting). This configuration eliminates the need to reheat the DRI before it enters the hot-compression unit. This saves cost and energy and ultimately increases the capacity of the manufacturing equipment.

[0212] Hot-compressed anodes can be manufactured at very low cost and with high-capacity equipment. To reduce loading and handling costs during manufacturing, the hot-compressed anode production line can be located alongside the DRI production facility. However, this hot-compressed anode equipment does not need to be integrated into the DRI production equipment. It may be advantageous to separate the two equipment sets described above so that the material can be pre-treated with DRI before being sent to the hot-compressed equipment to improve material properties related to porosity, shape, and adhesion.

[0213] Hot compression anode manufacturing equipment can be designed to be containerized (i.e., modular and mobile). This can be very advantageous, given that the equipment can be very expensive, and is likely to be used in specific projects where DRI is expected to be received from the nearest DRI plant to reduce loading and handling costs. Containerized hot compression anode manufacturing equipment can be described, but is not limited to, a heating, pressing, or rolling system fixed within a standard 40ft container(s); manufacturing equipment within a 45ft container(s), which may be equipped with a standard interface for integration into a DRI furnace, DRI handling equipment, and automated hot compression anode handling equipment. This allows for land or sea transport to the project or DRI manufacturing site. The equipment can be easily loaded to a DRI manufacturing site as close as possible to the form energy's energy storage facility. This containerized equipment may include decarburization capabilities.

[0214] The mechanisms used in hot compression anode manufacturing equipment can be described as, but are not limited to, the following design methodologies. A continuous roller system similar to those found in the architecture of hot briquetting equipment may be used. A semi-continuous process, such as a uniaxial press system, may be used. This may include automated material handling at the inlet and outlet of the uniaxial press to increase the capacity of the equipment. The press system may utilize the following actuation systems: hydraulic or pneumatic pistons; cam-driven actuation; lead screw-driven actuation; electromagnetic actuation. The mechanism may include guided parallel plates to ensure dimensional uniformity and stability of the compacted body.

[0215] The mechanisms used in hot compression anode manufacturing equipment can be described as, but are not limited to, the following design methodologies. A conveyor belt-like drive mechanism can be used to supply material to the press. This may be a standalone conveyor or a conveyor belt later incorporated into the anode electrode for current collection.

[0216] The mechanisms used in hot compression anode manufacturing apparatus can be described as, but are not limited to, the following design methodologies: a linear or rotary press (similar to a pill press) using multiple hot press zones and material handling that accommodates multiple parallel or stepped hot press zones; this apparatus can produce electrodes in shape factors or in the form of small (10cm x 10cm) tiles or large (100cm x 100cm) panels.

[0217] The anode assembly may include an integrated current collector.

[0218] An actuation method for pressing materials together can also function as an actuation method for cutting an integrated current collector from a continuous sheet.

[0219] System architecture for an embodiment of a hot-compression anode

[0220] The reactor architecture ideally utilizes large-area (approximately 1 m²) metallurgically bonded anode electrodes fabricated directly from the DRI or upstream material of the steelmaking process. Large-area electrodes are difficult to manufacture by press or roller manufacturing processes, as they require very large and rigid press equipment. It may be advantageous to construct large-area electrodes from smaller pieces fabricated with smaller, simpler automated equipment. Hot-compressed anodes may be assembled using smaller hot-compressed anode units, which are then joined. Methods of assembly include, but are not limited to, direct electromechanical welding, forging, thermal bonding, or electrochemical sintering to either the DRI compacted body or any incorporated and / or protruding current collectors.

[0221] When using a large roller with a cutting feature for forming a sheet-like compacted material, the anode electrode can be manufactured in panel or small piece (30cm x 30cm) form using the hot roller method. The material is formed in the void portion of the roller's cutting section. As the roller rotates and cuts off the segments at the ends of the roller, the sheet-like compacted material is "caught" and cut into a sheet shape.

[0222] The method described above can also be used to create an anode assembly when multiple DRI consolidation bodies are formed and connected to a single steel mesh current collector. This string assembly can then be handled in a continuous form or cut at a later stage for easier handling.

[0223] Conversely, a continuous process can produce continuous sheets of material. This material can be continuously pulled for a continuous or semi-continuous press system and cut in a later processing step in the manufacturing process line.

[0224] Including DRI can be difficult and costly, and a simple way to circumvent this problem is to create small packets of DRI for handling and containment. These packets can then be compressed directly in a hot press. These packets can be made from either a metal mesh-like material or a plastic material. If made from plastic, the packet casing may burn out thermally in later stages of the anode manufacturing process.

[0225] Current collection method from metallurgically joined electrodes

[0226] Collecting current from some metallurgically joined iron electrode architectures, particularly iron electrodes manufactured by welding or hot compaction, is difficult. More specifically, the high currents generated from such electrodes often require welded connections, which can be difficult to weld directly to electrodes made of highly porous iron materials. In some examples, current-collecting material that can be easily connected to busbars or terminals can be embedded within or on the surface of the electrode, or at the ends of the electrode that must be connected to an external circuit. The current-collecting material may consist of metal strips, mesh sheets, perforated sheets, non-uniform branched metal fabrics, or wires. In some embodiments, the current-collecting material may be incorporated into the electrode during the same metallurgical joining process that joins the porous fine-grained iron material to itself, while in other embodiments, the current-collecting body may be incorporated into or joined to the electrode in a second joining step. The current-collecting material may consist of any material suitable for manufacturing electrode current-collecting bodies in the art. In some embodiments, the current-collecting body is made of steel, nickel, and / or copper. In some embodiments, a less expensive current collector material, such as nickel-plated steel, may be coated with a corrosion-resistant material.

[0227] In some embodiments, the current collector material can spread over the entire surface of the electrode, while in other embodiments, the current collector may be embedded only in the vicinity of the part of the electrode close to the terminal in order to facilitate welding to adjacent external circuit elements. When the current collector is embedded only in a part of the electrode, the current collector may be embedded in the side of the electrode manufactured by the rolling process. For example, as shown in FIG. 13, the electrode may be connected to an external circuit through the current collector embedded in this side. The hopper may be installed above the roller and may create a slot to allow the passage of the "tab-strand". The tab-strand may be compressed by iron in the nip at a desired frequency. Also, the downstream of the slitter can remove the carrier. If the tab-strand needs to be the length of the slab, a similar cutout may be made on the opposite side.

[0228] In some embodiments, the metallurgically joined electrode may have holes for attaching bolts and ring terminals for current collection.

[0229] In some embodiments, the busbar is metallurgically joined directly to the metallurgically joined electrode.

[0230] In some embodiments, the current collector can function as a basket for containing the material during a pressing or welding operation, enabling material containment and further allowing the current collector to be joined to the active material.

[0231] In some embodiments, the structural surface layer 1410 may be applied to one or both sides of the anode. This is similar to the paper surface on a drywall panel, without which the drywall sheet would be very weak and nearly impossible to handle. The surface layer 1410 may be fabricated from a suitable metallic material (such as steel or nickel) in a suitable format (such as wire mesh, expanded metal, or perforated sheet). In some cases, the surface layer 1410 may be fabricated from plastic or another non-metallic material. The surface layer 1410 may be bonded to the DRI 1420 as part of a bonding process (regardless of the use of rollers 1430, a uniaxial press, or another process), so that the surface layer is bonded integrally to the surface of the anode. The surface layer 1410 may be conceived out of the potential need for additional mechanical robustness, but it may also serve as a current collector. Furthermore, it can also function as a retaining screen to ensure that loose particles of DRI1420 (whether they failed to bond during hot consolidation or loosened after the cycle) do not move from the anode envelope and interfere with the cell's function. The surface layer 1410 can also serve as a mechanical interface structure, thereby allowing the anode to be attached to other elements of the cell during assembly. During anode manufacturing, the surface layer 1410 can function, for example, by acting as a conveyor that can weigh and transport DRI1420 to the consolidation process. In some embodiments, perforated steel mesh may be bonded to both sides of the electrode to form a sandwich structure with a current-collecting structural element on the surface that simultaneously enhances current collection, mechanical integrity, and handling. The structural surface of the electrode does not have to be a current-collecting element and may be made of plastic or other suitable material. An example of how a structural surface is applied to an electrode is shown in Figure 14.

[0232] Various embodiments can provide devices and / or methods for use in bulk energy storage systems, such as long-term energy storage (LODES) systems and short-term energy storage (SDES) systems. For example, various embodiments can provide batteries for bulk energy storage systems, such as batteries for LODES systems. Renewable energy sources are becoming increasingly widespread and cost-effective. However, many renewable energy sources face intermittency issues that hinder their adoption. The impact of the intermittency tendency of renewable energy sources can be mitigated by pairing them with bulk energy storage systems, such as LODES systems and SDES systems. To support the adoption of combined power generation, transmission, and storage systems (e.g., renewable power sources paired with bulk energy storage systems, and power plants having transmission equipment in either the power plant or the bulk energy storage system), devices and methods are needed to support the design and operation of such combined power generation, transmission, and storage systems, including the various embodiments of devices and methods described herein.

[0233] A combined-use power generation, transmission, and storage system may be a power plant comprising one or more power sources (e.g., one or more renewable power sources, one or more non-renewable power sources, or a combination of renewable and non-renewable power sources), one or more transmission facilities, and one or more bulk energy storage systems. The transmission facilities in either the power plant or / or bulk energy storage system may be optimized concurrently with the power generation and storage systems, or they may impose constraints on the design and operation of the power generation and storage systems. A combined-use power generation, transmission, and storage system can be configured to meet various output targets under various design and operational constraints.

[0234] Figures 15-23 illustrate various exemplary systems in which one or more aspects of the various embodiments can be used as part of a bulk energy storage system such as a LODES system or an SDES system. For example, the various embodiments described herein with reference to Figures 1-32 can be used as batteries for a bulk energy storage system such as a LODES system or an SDES system, and / or the various electrodes described herein can be used as components of a bulk energy storage system. As used herein, the term “LODES system” means a bulk energy storage system configured to have a rated duration (energy / power ratio) of 24 hours (h) or longer, such as a 24-hour duration, a 24-to-50-hour duration, a duration longer than 50 hours, a 24-to-150-hour duration, a duration longer than 150 hours, a 24-to-200-hour duration, a duration longer than 200 hours, a 24-to-500-hour duration, or a duration longer than 500 hours.

[0235] Figure 15 shows an exemplary system in which one or more aspects of various embodiments can be used as part of a bulk energy storage system. Specifically, a bulk energy storage system incorporating one or more aspects of various embodiments may be the LODES system 1504. For example, the LODES system 1504 may include batteries of various embodiments described herein, various electrodes described herein, and the like. The LODES system 1504 may be electrically connected to a wind power station 1502 and one or more power transmission facilities 1506. The wind power station 1502 may be electrically connected to the power transmission facility 1506. The power transmission facility 1506 may be electrically connected to a power distribution network 1508. The wind power station 1502 can generate electricity and output the generated electricity to the LODES system 1504 and / or the power transmission facility 1506. The LODES system 1504 can store the electricity received from the wind power station 1502 and / or the power transmission facility 1506. The LODES system 1504 can output the stored power to the transmission equipment 1506. The transmission equipment 1506 can output power received from either or both of the wind power station 1502 and the LODES system 1504 to the distribution network 1508, and / or can receive power from the distribution network 1508 and output that power to the LODES system 1504. Together, the wind power station 1502, the LODES system 1504, and the transmission equipment 1506 can constitute a power plant 1500, which may be a combined power generation, transmission, and storage system. Power generated by the wind power station 1502 may be directly transmitted to the distribution network 1508 via the transmission equipment 1506, or it may first be stored in the LODES system 1504. In certain cases, the electricity supplied to the power distribution network 1508 may be entirely from the wind power station 1502, entirely from the LODES system 1504, or from a combination of the wind power station 1502 and the LODES system 1504.The distribution of electricity from the combined wind power base 1502 and the LODES system 1504 power plant 1500 may be controlled according to a predetermined long-term (multiple days or even more years) schedule, or according to the day-ahead (15-hour prior notice) market, or according to the hour-ahead market, or according to actual pricing factors.

[0236] As one example of the operation of power plant 1500, the LODES system 1504 can be used to reshape and "stabilize" the power produced by wind turbine 1502. In one such example, wind turbine 1502 may have a peak power output (capacity) of 260 megawatts (MW) and a capacity factor (CF) of 41%. The LODES system 1504 may have a power rating (capacity) of 106 MW, a rated duration (energy / power ratio) of 150 hours (h), and a rated energy of 15,900 megawatt-hours (MWh). In another such example, wind turbine 1502 may have a peak power output (capacity) of 300 MW and a capacity factor (CF) of 41%. The LODES system 1504 may have a power rating (capacity) of 106 MW, a rated duration (energy / power ratio) of 200 hours, and a rated energy of 21,200 MWh. In another such example, wind power station 1502 may have a peak power output (capacity) of 176 MW and a capacity factor (CF) of 53%. LODES system 1504 may have a power rating (capacity) of 88 MW, a rated duration (energy / power ratio) of 150 hours, and a rated energy of 13,200 MWh. In yet another such example, wind power station 1502 may have a peak power output (capacity) of 277 MW and a capacity factor (CF) of 41%. LODES system 1504 may have a power rating (capacity) of 97 MW, a rated duration (energy / power ratio) of 50 hours, and a rated energy of 4,850 MWh. In yet another such example, wind power station 1502 may have a peak power output (capacity) of 315 MW and a capacity factor (CF) of 41%. The LODES system 1504 may have a power rating (capacity) of 110 MW, a rated duration (energy / power ratio) of 25 hours, and a rated energy of 2,750 MWh.

[0237] Figure 16 shows an exemplary system in which one or more aspects of various embodiments can be used as part of a bulk energy storage system. Specifically, a bulk energy storage system incorporating one or more aspects of various embodiments may be a LODES system 1504. For example, the LODES system 1504 may include batteries of various embodiments described herein, various electrodes described herein, and the like. The system in Figure 16 may be similar to the system in Figure 15, except that a photovoltaic (PV) base station 1602 may be used instead of a wind power base station 1502. The LODES system 1504 may be electrically connected to the PV base station 1602 and one or more power transmission facilities 1506. The PV base station 1602 may be electrically connected to the power transmission facility 1506. The power transmission facility 1506 may be electrically connected to the power distribution network 1508. The PV base station 1602 can generate electricity, and the PV base station 1602 can output the generated electricity to the LODES system 1504 and / or power transmission facility 1506. The LODES system 1504 can store electricity received from the PV base station 1602 and / or the transmission equipment 1506. The LODES system 1504 can output the stored electricity to the transmission equipment 1506. The transmission equipment 1506 can output electricity received from either or both of the PV base station 1602 and the LODES system 1504 to the distribution network 1508, and / or can receive electricity from the distribution network 1508 and output that electricity to the LODES system 1504. Together, the PV base station 1602, the LODES system 1504, and the transmission equipment 1506 can constitute a power plant 1600, which may be a combined power generation, transmission, and storage system. Electricity generated by the PV base station 1602 may be directly supplied to the distribution network 1508 via the transmission equipment 1506, or it may first be stored in the LODES system 1504. In certain cases, the power supplied to the distribution network 1508 may be entirely from the PV base station 1602, entirely from the LODES system 1504, or from a combination of the PV base station 1602 and the LODES system 1504.The distribution of electricity from the combined PV base station 1602 and the LODES system 1504 power plant 1600 may be controlled according to a predetermined long-term (multiple days or even more years) schedule, or according to the day-ahead (24-hour prior notice) market, or according to the hour-ahead market, or according to real-time pricing signals.

[0238] As one example of the operation of power plant 1600, the LODES system 1504 can be used to reshape and "stabilize" the power produced by PV base station 1602. In one such example, PV base station 1602 may have a peak power output (capacity) of 490 MW and a capacity factor (CF) of 24%. The LODES system 1504 may have a power rating (capacity) of 340 MW, a rated duration (energy / power ratio) of 150 hours, and a rated energy of 51,000 MWh. In another such example, PV base station 1602 may have a peak power output (capacity) of 680 MW and a capacity factor (CF) of 24%. The LODES system 1504 may have a power rating (capacity) of 410 MW, a rated duration (energy / power ratio) of 200 hours, and a rated energy of 82,000 MWh. In another such example, PV base station 1602 may have a peak power output (capacity) of 330 MW and a capacity factor (CF) of 31%. LODES system 1504 may have a power rating (capacity) of 215 MW, a rated duration (energy / power ratio) of 150 hours, and a rated energy of 32,250 MWh. In another such example, PV base station 1602 may have a peak power output (capacity) of 510 MW and a capacity factor (CF) of 24%. LODES system 1504 may have a power rating (capacity) of 380 MW, a rated duration (energy / power ratio) of 50 hours, and a rated energy of 19,000 MWh. In yet another such example, PV base station 1602 may have a peak power output (capacity) of 630 MW and a capacity factor (CF) of 24%. The LODES system 1504 may have a power rating (capacity) of 380 MW, a rated duration (energy / power ratio) of 25 hours, and a rated energy of 9,500 MWh.

[0239] Figure 17 shows an exemplary system in which one or more aspects of various embodiments can be used as part of a bulk energy storage system. Specifically, a bulk energy storage system incorporating one or more aspects of various embodiments may be the LODES system 1504. For example, the LODES system 1504 may include batteries of various embodiments described herein, electrodes of various embodiments described herein, and the like. The system in Figure 17 may be similar to the systems in Figures 15 and 16, except that both the wind power station 1502 and the photovoltaic (PV) station 1602 may be power generation devices operating together in the power plant 1700. The PV station 1602, the wind power station 1502, the LODES system 1504, and the transmission equipment 1506 together can constitute the power plant 1700, which may be a combined power generation, transmission, and storage system. The electricity generated by the PV base station 1602 and / or the wind power station 1502 may be directly supplied to the distribution network 1508 via the transmission equipment 1506, or it may first be stored in the LODES system 1504. In certain cases, the electricity supplied to the distribution network 1508 may be all from the PV base station 1602, all from the wind power station 1502, all from the LODES system 1504, or from a combination of the PV base station 1602, the wind power station 1502, and the LODES system 1504. The distribution of electricity from the combined wind power station 1502, PV base station 1602, and LODES system 1504 power plant 1700 may be controlled according to a predetermined long-term (multiple days or even more years) schedule, or according to the day-ahead (24-hour prior notice) market, or according to the hour-ahead market, or according to real-time pricing signals.

[0240] As one example of the operation of power plant 1700, the LODES system 1504 can be used to reshape and "stabilize" the power produced by wind turbine 1502 and PV turbine 1602. In one such example, wind turbine 1502 may have a peak power output (capacity) of 126 MW and a capacity factor (CF) of 41%, and PV turbine 1602 may have a peak power output (capacity) of 126 MW and a capacity factor (CF) of 24%. The LODES system 1504 may have a power rating (capacity) of 63 MW, a rated duration (energy / power ratio) of 150 hours, and a rated energy of 9,450 MWh. In another such example, wind power station 1502 may have a peak power output (capacity) of 170 MW and a capacity factor (CF) of 41%, and PV station 1602 may have a peak power output (capacity) of 110 MW and a capacity factor (CF) of 24%. LODES system 1504 may have a power rating (capacity) of 57 MW, a rated duration (energy / power ratio) of 200 hours, and a rated energy of 11,400 MWh. In another such example, wind power station 1502 may have a peak power output (capacity) of 105 MW and a capacity factor (CF) of 51%, and PV station 1602 may have a peak power output (capacity) of 70 MW and a capacity factor (CF) of 31%. LODES system 1504 may have a power rating (capacity) of 61 MW, a rated duration (energy / power ratio) of 150 hours, and a rated energy of 9,150 MWh. In another such example, wind power station 1502 may have a peak power output (capacity) of 135 MW and a capacity factor (CF) of 41%, and PV station 1602 may have a peak power output (capacity) of 90 MW and a capacity factor (CF) of 24%. LODES system 1504 may have a power rating (capacity) of 68 MW, a rated duration (energy / power ratio) of 50 hours, and a rated energy of 3,400 MWh. In another such example, wind power station 1502 may have a peak power output (capacity) of 144 MW and a capacity factor (CF) of 41%, and PV station 1602 may have a peak power output (capacity) of 96 MW and a capacity factor (CF) of 24%.The LODES system 1504 may have a power rating (capacity) of 72 MW, a rated duration (energy / power ratio) of 25 hours, and a rated energy of 1,800 MWh.

[0241] Figure 18 shows an exemplary system in which one or more aspects of various embodiments can be used as part of a bulk energy storage system. Specifically, a bulk energy storage system incorporating one or more aspects of various embodiments may be the LODES system 1504. For example, the LODES system 1504 may include batteries of the various embodiments described herein, electrodes of the various embodiments described herein, etc. The LODES system 1504 may be electrically connected to one or more power transmission facilities 1506. In this way, the LODES system 1504 can operate in a “standalone” manner to arbitrage energy near market prices and / or avoid power transmission constraints. The LODES system 1504 may be electrically connected to one or more power transmission facilities 1506. The power transmission facilities 1506 may be electrically connected to a distribution network 1508. The LODES system 1504 can store power received from the power transmission facilities 1506. The LODES system 1504 can output the stored power to the power transmission facilities 1506. The power transmission equipment 1506 can output power received from the LODES system 1504 to the distribution network 1508, and / or receive power from the distribution network 1508 and output that power to the LODES system 1504.

[0242] The LODES system 1504 and the transmission equipment 1506 together can constitute a power plant 900. As an example, the power plant 900 may be located downstream of the transmission constraints, closer to power consumption. In such an exemplary downstream power plant 1800, the LODES system 1504 may have a duration of 24 to 500 hours and may undergo one or more full discharges per year to support peak power consumption at times when transmission capacity is insufficient to serve customers. In addition, in such an exemplary downstream power plant 1800, the LODES system 1504 may undergo several shallow discharges (daily or more frequently) to arbitrage the difference between nighttime and daytime electricity prices and reduce the overall cost of electricity services to customers. As a further example, the power plant 1800 may be located upstream of the transmission constraints, closer to power generation. In such exemplary upstream power plants 1800, the LODES system 1504 may have a duration of 24 to 500 hours and may undergo full charges once or more times a year to absorb excess power generation when transmission capacity is insufficient to distribute electricity to customers. In addition, in such exemplary upstream power plants 1800, the LODES system 1504 may undergo several shallow charge-discharge cycles (daily or more frequently) to arbitrage the difference between nighttime and daytime electricity prices and maximize the value of the power generation equipment's output.

[0243] Figure 19 shows an exemplary system in which one or more aspects of various embodiments can be used as part of a bulk energy storage system. Specifically, a bulk energy storage system incorporating one or more aspects of various embodiments may be the LODES system 1504. For example, the LODES system 1504 may include batteries of the various embodiments described herein, various electrodes described herein, and the like. The LODES system 1504 may be electrically connected to commercial and industrial (C&I) customers 1902, such as data centers and factories. The LODES system 1504 may be electrically connected to one or more power transmission facilities 1506. The power transmission facilities 1506 may be electrically connected to a power distribution network 1508. The power transmission facilities 1506 can receive power from the power distribution network 1508 and output that power to the LODES system 1504. The LODES system 1504 can store the power received from the power transmission facilities 1506. The LODES system 1504 can output the stored power to the C&I customers 1902. In this way, the LODES system 1504 can reshape the electricity purchased from the distribution network 1508 to match the consumption patterns of the C&I customer 1902.

[0244] The LODES system 1504 and the transmission equipment 1506 can together constitute a power plant 1900. As an example, the power plant 1900 may be located near electricity consumption, i.e., near C&I customer 1902, such as between the distribution network 1508 and C&I customer 1902. In such an example, the LODES system 1504 may have a duration of 24 to 500 hours and may purchase electricity from the market when electricity is cheaper, thereby charging the LODES system 1504. The LODES system 1504 can then discharge when market prices are high to provide electricity to C&I customer 1902, thus offsetting C&I customer 1902's market purchases. As an alternative configuration, the power plant 1900 may be located not between the distribution network 1508 and C&I customer 1902, but between renewable resources such as PV bases and wind power bases and the transmission equipment 1506 which may be connected to renewable resources. In such alternative examples, the LODES system 1504 may have a duration of 24 to 500 hours, and the LODES system 1504 may be charged at a time when renewable output may be available. The LODES system 1504 can then discharge to cover part or all of the C&I customer 1902's electricity needs, thereby providing the C&I customer 1902 with renewable generated electricity.

[0245] Figure 20 shows an exemplary system in which one or more aspects of the various embodiments can be used as part of a bulk energy storage system. Specifically, a bulk energy storage system incorporating one or more aspects of the various embodiments may be the LODES system 1504. For example, the LODES system 1504 may include batteries of the various embodiments described herein, various electrodes described herein, and the like. The LODES system 1504 may be electrically connected to a wind power station 1502 and one or more power transmission facilities 1506. The wind power station 1502 may be electrically connected to the power transmission facility 1506. The power transmission facility 1506 may be electrically connected to a C&I customer 1902. The wind power station 1502 can generate electricity, and the wind power station 1502 can output the generated electricity to the LODES system 1504 and / or the power transmission facility 1506. The LODES system 1504 can store the electricity received from the wind power station 1502.

[0246] The LODES system 1504 can output the stored power to the transmission equipment 1506. The transmission equipment 1506 can output the power received from either or both of the wind turbine 1502 and the LODES system 1504 to the C&I customer 1902. Together, the wind turbine 1502, the LODES system 1504, and the transmission equipment 1506 can constitute a power plant 2000, which may be a combined power generation, transmission, and storage system. The power generated by the wind turbine 1502 may be supplied directly to the C&I customer 1902 via the transmission equipment 1506, or it may be first stored in the LODES system 1504. In certain cases, the power supplied to the C&I customer 1902 may be supplied entirely from the wind turbine 1502, entirely from the LODES system 1504, or from a combination of the wind turbine 1502 and the LODES system 1504. The LODES system 1504 may be used to reshape the electricity generated by the wind turbine 1502 to match the consumption patterns of the C&I customer 1902. In one such example, the LODES system 1504 may have a duration of 24 to 500 hours and may be charged when renewable power generation by the wind turbine 1502 exceeds the load of the C&I customer 1902. The LODES system 1504 may then be discharged when renewable power generation by the wind turbine 1502 falls below the load of the C&I customer 1902 to provide the C&I customer 1902 with a stable renewable profile that offsets some or all of the C&I customer 1902's electricity consumption.

[0247] Figure 21 shows an exemplary system in which one or more aspects of various embodiments can be used as part of a bulk energy storage system. Specifically, a bulk energy storage system incorporating one or more aspects of various embodiments may be the LODES system 1504. For example, the LODES system 1504 may include batteries of the various embodiments described herein, various electrodes described herein, and the like. The LODES system 1504 integrates a large amount of renewable energy into a microgrid, for example, harmonizing the output of renewable energy from PV bases 1602 and wind power bases 1502 with existing thermal power from, for example, a thermal power plant 2102 (e.g., a gas plant, coal plant, diesel generator set, etc., or a combination of thermal power methods), and may be part of a power plant 2100 that supplies C&I customer 1902 loads when the availability rate is high. A microgrid such as the one composed of power plant 2100 and thermal power plant 2102 can provide an availability rate of 90% or higher. The electricity generated by PV base station 1602 and / or wind power base station 1502 may be supplied directly to C&I customer 1902, or it may first be stored in LODES system 1504.

[0248] In certain cases, the electricity supplied to C&I customer 1902 may be supplied entirely from PV terminal 1602, entirely from wind terminal 1502, entirely from LODES system 1504, entirely from thermal power plant 2102, or from any combination of PV terminal 1602, wind terminal 1502, LODES system 1504, and / or thermal power plant 2102. As an example, the LODES system 1504 of power plant 2100 may have a duration of 24 to 500 hours. In a specific example, the load on C&I customer 1902 may have a peak of 100 MW, the LODES system 1504 may have a power rating of 14 MW and a duration of 150 hours, the cost of natural gas may be $6 per million British pound thermal energy (MMBTU), and the renewable occupancy rate may be 58%. As another specific example, the C&I customer 1902 load may have a peak of 100 MW, the LODES system 1504 may have a power rating of 25 MW and a duration of 150 hours, the cost of natural gas may be $8 per million British pound thermal energy (MMBTU), and the renewable occupancy rate may be 65%.

[0249] Figure 22 shows an exemplary system in which one or more aspects of the various embodiments can be used as part of a bulk energy storage system. Specifically, a bulk energy storage system incorporating one or more aspects of the various embodiments may be the LODES system 1504. For example, the LODES system 1504 may include batteries of the various embodiments described herein, various electrodes described herein, and the like. Using the LODES system 1504, a nuclear power plant 2202 (or other inflexible power generation facilities such as thermal, biomass, and / or any other type of power plant with a ramp speed of less than 50% of rated power per hour and a capacity factor of 80% or higher) can be enhanced to add flexibility to the combined output of the power plant 2200, which is comprised of the combined LODES system 1504 and the nuclear power plant 2202. The nuclear power plant 2202 can operate at a high capacity factor and at its highest efficiency point, and the LODES system 1504 can be charged and discharged to effectively reshape the output of the nuclear power plant 2202 to match customer electricity consumption and / or market prices for electricity. For example, the LODES system 1504 of power plant 2200 may have a duration of 24 to 500 hours. In one specific example, nuclear power plant 2202 may have a rated output of 1000 MW, and nuclear power plant 2202 may be forced to perform minimum stable power generation or even shutdown for a long period due to a decline in the market price of electricity. The LODES system 1504 can avoid facility shutdown when market prices fall and can be charged, and then the LODES system 1504 can discharge when market prices rise and restore total power generation.

[0250] Figure 23 shows an exemplary system in which one or more aspects of various embodiments can be used as part of a bulk energy storage system. Specifically, a bulk energy storage system incorporating one or more aspects of various embodiments may be the LODES system 1504. For example, the LODES system 1504 may include batteries of the various embodiments described herein, various electrodes described herein, and the like. The LODES system 1504 can operate in conjunction with the SDES system 2302. Together, the LODES system 1504 and the SDES system 2302 may constitute a power plant 2300. For example, the LODES system 1504 and the SDES system 2302 can be optimized simultaneously, thereby enabling the LODES system 1504 to provide various services, including long-term backup and / or bridging, over multi-day fluctuations (e.g., market prices, renewable power generation, electricity consumption, etc.). The SDES system 2302 can provide a range of services, including rapid auxiliary services (e.g., voltage control, frequency regulation, etc.) and / or bridging, across daytime fluctuations (e.g., daytime fluctuations such as market prices, renewable power generation, and electricity consumption). The SDES system 2302 may have a duration of less than 10 hours and a round-trip efficiency greater than 80%. The LODES system 1504 may have a duration of 24 to 500 hours and a round-trip efficiency greater than 40%. In one such example, the LODES system 1504 may have a duration of 150 hours and can support customer electricity consumption for up to one week of renewable power shortages. The LODES system 1504 can also enhance the capacity of the SDES system 2302 to support customer electricity consumption during daytime power shortage events. Furthermore, the SDES system 2302 can supply customers during daytime power shortage events and provide quality services such as power regulation, voltage control, and frequency regulation.

[0251] Various embodiments may include a battery including a first electrode, an electrolyte, and a second electrode, wherein at least one of the first electrode and the second electrode includes an iron mass product. In some embodiments, the electrolyte includes a soluble sulfide. In some embodiments, at least one of the first electrode and the second electrode further includes a solid sulfide. In some embodiments, at least one of the first electrode or the second electrode is under a compressive load. In some embodiments, the compressive load is applied by a current collector member to one side of at least one of the first electrode or the second electrode. In some embodiments, the iron mass product includes at least one of magnetite, hematite, or wustite. In some embodiments, the electrolyte includes a corrosion inhibitor. In some embodiments, the iron mass product has an average length in the range of about 50 μm to about 50 mm. In some embodiments, the iron mass product has an average internal porosity in the range of about 10% to about 90% by volume. In some embodiments, the iron mass product has an average specific surface area in the range of about 0.1 m 2 / g to about 25 m 2 / g. In some embodiments, the electrolyte is infiltrated between the iron mass products. In some embodiments, the electrolyte includes 1-octanethiol. In some embodiments, the electrolyte includes molybdate anions and sulfide anions. In some embodiments, the iron mass product is supported within a metallic woven mesh that provides compressive force and current collection to the iron mass product. In some embodiments, the iron mass products are joined to each other and joined to a current collector.

[0252] Various embodiments include a battery comprising a first electrode, an electrolyte, and a second electrode, wherein at least one of the first and second electrodes contains atomized metal powder. In some embodiments, the electrolyte contains a soluble sulfide. In some embodiments, at least one of the first and second electrodes further contains a solid sulfide. In some embodiments, at least one of the first or second electrode is subjected to a compressive load. In some embodiments, the compressive load is applied by a current collector to one side of at least one of the first or second electrode. In some embodiments, the atomized metal powder contains at least one of magnetite, hematite, or wustite. In some embodiments, the electrolyte contains a corrosion inhibitor. In some embodiments, the electrolyte is impregnated between the atomized metal powder particles. In some embodiments, the electrolyte contains 1-octanthiol. In some embodiments, the electrolyte contains molybdate anions and sulfide anions. In some embodiments, the atomized metal powder is supported within a metal woven mesh that provides compressive force and current collection to the atomized metal powder. In some embodiments, the atomized metal powder is bonded together and bonded to a current collector.

[0253] Various embodiments may include methods for fabricating electrodes, comprising electrochemically producing a metal powder and forming the metal powder into an electrode. In some embodiments, the electrochemical production of the metal powder includes, at least in part, the production of the metal powder using molten salt electrochemistry. In some embodiments, the electrochemical production of the metal powder includes, at least in part, the production of the metal powder using a gas atomization method. In some embodiments, the electrochemical production of the metal powder includes, at least in part, the production of the metal powder using a water atomization method.

[0254] Various embodiments include a bulk energy storage system including one or more batteries, wherein at least one of the one or more batteries includes a first electrode, an electrolyte, and a second electrode, and at least one of the first electrode and the second electrode includes an iron mass composition. In some embodiments, the bulk energy storage system is a long-term energy storage (LODES) system. In some embodiments, the electrolyte includes a soluble sulfide. In some embodiments, at least one of the first electrode and the second electrode further includes a solid sulfide. In some embodiments, at least one of the first electrode or the second electrode is under a compressive load. In some embodiments, the compressive load is applied by a current collector member to one side of at least one of the first electrode or the second electrode. In some embodiments, the iron mass composition includes at least one of magnetite, hematite, or wustite. In some embodiments, the electrolyte includes a corrosion inhibitor. In some embodiments, the iron mass composition has an average length in the range of about 50 um to about 50 mm. In some embodiments, the iron mass composition has an average internal porosity in the range of about 10 volume % to about 90 volume %. In some embodiments, the iron mass composition has an average specific surface area in the range of about 0.1 m 2 / g to about 25 m 2 / g. In some embodiments, the electrolyte is infiltrated between the iron mass compositions. In some embodiments, the electrolyte includes 1-octanethiol. In some embodiments, the electrolyte includes molybdate anions and sulfide anions. In some embodiments, the iron mass composition is supported within a metallic woven mesh that provides a compressive force and current collection to the iron mass composition. In some embodiments, the iron mass compositions are joined to each other and joined to a current collector.

[0255] Various embodiments include a bulk energy storage system comprising one or more batteries, where at least one of the batteries comprises a first electrode, an electrolyte, and a second electrode, and at least one of the first electrode and the second electrode comprises atomized metal powder. In some embodiments, the bulk energy storage system is a long-term energy storage (LODES) system. In some embodiments, the electrolyte comprises a soluble sulfide. In some embodiments, at least one of the first electrode and the second electrode further comprises a solid sulfide. In some embodiments, at least one of the first electrode or the second electrode is subjected to a compressive load. In some embodiments, the compressive load is applied by a current collector to one side of at least one of the first electrode or the second electrode. In some embodiments, the atomized metal powder comprises at least one of magnetite, hematite, or wustite. In some embodiments, the electrolyte comprises a corrosion inhibitor. In some embodiments, the electrolyte is impregnated between the atomized metal powder particles. In some embodiments, the electrolyte comprises 1-octanthiol. In some embodiments, the electrolyte comprises molybdate anions and sulfide anions. In some embodiments, the atomized metal powder is supported within a metal woven mesh that provides compressive force and current collection to the atomized metal powder. In some embodiments, the atomized metal powders are bonded together and bonded to a current collector.

[0256] Implementation examples are described in the following paragraphs. Some of the following implementation examples are described in terms of illustrative methods, but further illustrative implementations may include the illustrative methods discussed in the following paragraphs that are implemented to form iron electrodes and / or electrochemical systems.

[0257] Example 1. A method for manufacturing an iron electrode, comprising the steps of: providing a particulate iron material to an apparatus; and applying pressure and / or heat to the particulate iron material in the apparatus over a period of time to form an electrode having conductive connections between the particles of the particulate iron material.

[0258] Example 2. The method according to Example 1, further comprising the step of providing electrodes into an electrochemical system without applying an external current collector or filling the electrodes.

[0259] Example 3. The apparatus according to Example 1 or 2, wherein the apparatus includes a compaction roller, and the applied pressure is generated at least partially by the compaction roller.

[0260] Example 4. The method according to Example 1 or 2, wherein pressure and / or heat are applied in a hot isostatic pressing (HIP) process, uniaxial hot pressing, hot rolling densification process, hot briquetting process, or hot forging process.

[0261] Example 5. The method according to any one of Examples 1 to 4, wherein the applied heat produces a high temperature in the range of about 300 to about 1000°C; the applied pressure is in the range of about 0.1 to about 200 MPa; the applied pressure is applied by uniaxial, biaxial, triaxial, isotropic and / or roller methods; and / or the time is in the range of about 1 second to about 24 hours.

[0262] Example 6. The method according to Example 5, wherein the applied pressure is in the range of approximately 1 to approximately 100 MPa.

[0263] Example 7. The method according to any one of Examples 1 to 6, wherein the microporosity of more than 50 volume percent within the particles of the fine iron material is maintained after the application of pressure and high temperature.

[0264] Example 8. The electrode is the method according to any one of Examples 1 to 7, wherein the electrode has more than 50 volume percent microporosity within the particles of the fine iron material after the application of pressure and high temperature.

[0265] Example 9. The method according to any one of Examples 1 to 8, wherein pressure and / or heat are applied in a non-oxidizing atmosphere.

[0266] Example 10. The method according to any one of Examples 1 to 8, further comprising the step of removing oxidation after electrode formation.

[0267] Example 11. The method according to any one of Examples 1 to 10, further comprising the step of forming a texture on an iron electrode.

[0268] Example 12. The texture is the method according to Example 11, comprising channels of variable thickness.

[0269] Example 13. The method according to any one of Examples 1 to 12, wherein the apparatus comprises a tool portion having a conical projection.

[0270] Example 14. The apparatus is the method according to any one of Examples 1 to 12, wherein the apparatus comprises a toothed roller.

[0271] Example 15. The apparatus is the method according to any one of Examples 1 to 12, wherein the apparatus comprises a textured roller.

[0272] Example 16. The method according to any one of Examples 1 to 15, further comprising the step of performing surface cleaning of the particulate iron material before providing the particulate iron material to the apparatus.

[0273] Example 17. The method according to any one of Examples 1 to 16, further comprising the steps of preheating the particulate iron material and / or mechanically modifying one or more aspects of the particulate iron material before providing it to the apparatus.

[0274] Example 18. The method according to any one of Examples 1 to 17, further comprising the step of controlling the particle size of the iron particulate material before providing the iron particulate material to the apparatus.

[0275] Example 19. The method according to Example 18, wherein the step of controlling the particle size of the fine iron particles includes reducing the particle size of the fine iron particles from a first particle size to a second particle size.

[0276] Example 20. The method according to Example 19, wherein the second particle size is half the size of the first particle size.

[0277] Example 21. The method according to Example 19, wherein the second particle size is one-quarter of the first particle size.

[0278] Example 22. The particle size reduction technique is the method according to any one of Examples 19 to 21, comprising one or more of jaw crushing, hammer milling, gyratory milling, and parallel plate pulverizing.

[0279] Example 23. The method according to any one of Examples 1 to 22, wherein the step of providing particulate iron material to the apparatus includes at least partially a thermal spraying process that causes a portion of the particulate iron material to adhere onto the substrate and / or the floor of the DRI.

[0280] Example 24. The method according to any one of Examples 1 to 22, wherein the step of providing the particulate iron material to the apparatus includes at least partially the use of an additive manufacturing process.

[0281] Example 25. The method according to any one of Examples 1 to 24, wherein the step of forming the electrode further comprises ultrasonic compaction / vibration, slicing, machining, cold compaction, cold extrusion, casting, differential temperature compaction, and at least one of bonding and compaction that at least partially form the electrode.

[0282] Example 26. The method according to any one of Examples 1 to 25, wherein the step of applying pressure and / or heat includes applying a pressure of about 0.5 to 50 MPa at room temperature or applying about 0.1 to 10 MPa at a temperature of >400°C and <1200°C.

[0283] Example 27. The method according to any one of Examples 1 to 26, comprising the step of applying heat to a particulate iron material, wherein iron carbide decomposes to produce iron and graphite.

[0284] Example 28. The method according to Example 27, wherein the applied heat is at a temperature of 300 to 727°C.

[0285] Example 29. The method according to any one of Examples 1 to 28, further comprising the step of applying pressure and / or heat in an oxygen atmosphere at a temperature of 700 to 900°C.

[0286] Example 30. An iron electrode manufactured by any of the methods described in Examples 1 to 29.

[0287] Example 31. An iron electrode comprising metallurgically bonded sponge iron particles, wherein the microporosity of the sponge iron particles is >50% by volume and the particle size of the sponge iron particles is >100 μm.

[0288] Example 32. The iron electrode according to Example 31, manufactured by the method described in any one of Examples 1 to 29.

[0289] Example 33. An electrochemical system comprising an iron electrode manufactured by the method described in any one of Examples 1 to 29, and / or an iron electrode described in any one of Examples 30 to 32.

[0290] Example 34. The electrochemical system described in Example 33, which is a long-term energy storage system.

[0291] The descriptions of the methods described above are provided merely as illustrative examples and are not intended to require or suggest that the steps of the various embodiments must be carried out in the order presented. As those skilled in the art will understand, the order of the steps in the embodiments described above can be carried out in any order. Words such as “then,” “next,” and “then” are not necessarily intended to limit the order of the steps, and such words may be used to guide the reader throughout the description of the method. Furthermore, all references to singular claim elements using, for example, the articles “a,” “an,” or “the” (“one” or “the aforementioned”) should not be construed as limiting the element to the singular form. Moreover, any step of any embodiment described herein can be used in any other embodiment.

[0292] The preceding descriptions of the embodiments of this disclosure are provided to enable those skilled in the art to manufacture or use the invention. Various modifications to these embodiments will be immediately apparent to those skilled in the art, and the basic principles set forth herein can be applied to other embodiments without departing from the scope of the invention. Accordingly, the invention is not intended to be limited to the embodiments shown herein, and the broadest scope should be given that is consistent with the principles and novel features disclosed herein.

Claims

1. A method for manufacturing an iron electrode, The process of supplying fine iron particles to the apparatus, The process includes applying pressure to the fine iron particles in the apparatus for a period of time to form electrodes having conductive connections between the particles of the fine iron particles, The step of providing the fine iron particle material to the apparatus includes at least in part a thermal spraying process that directly deposits a portion of the fine iron particle material onto a reduced iron bed and / or onto a substrate. method.

2. The method according to claim 1, wherein the apparatus includes a compaction roller, and the pressure applied to the apparatus is generated at least partially by the compaction roller.

3. The pressure applied to the apparatus is in the range of 0.1 to 200 MPa, The pressure applied to the apparatus is applied by a uniaxial, biaxial, triaxial, isotropic and / or roller method. The method according to claim 1.

4. The method according to claim 3, wherein the pressure applied to the apparatus is in the range of 1 to 100 MPa.

5. The method according to claim 1, wherein the electrode has more than 50 volume percent of microporosity within the particles of the fine iron material after the pressure is applied.

6. The method according to claim 1, wherein the pressure is applied in a non-oxidizing atmosphere.

7. The method according to claim 1, further comprising the step of removing oxide after the formation of the electrode.

8. The method according to claim 1, further comprising the step of forming a texture on the iron electrode.

9. The method according to claim 8, wherein the texture comprises channels of variable thickness.

10. The method according to claim 1, wherein the apparatus comprises a tool portion having a conical projection, a toothed roller, or a textured roller.

11. The method according to claim 1, further comprising the step of performing surface cleaning of the fine iron particles before applying the pressure to the fine iron particles in the apparatus.

12. The method according to claim 1, further comprising the steps of preheating the fine iron particles and controlling the particle size of the fine iron particles before providing the fine iron particles to the apparatus.

13. The method according to claim 1, further comprising the step of controlling the particle size of the fine iron material before providing it to the apparatus.

14. The method according to claim 13, wherein the step of controlling the particle size of the fine iron material before providing the fine iron material to the apparatus includes the step of reducing the particle size of the fine iron material from a first particle size to a second particle size.

15. The method according to claim 14, wherein the second particle size is one-quarter of the first particle size.

16. The method according to claim 14, wherein the step of reducing the particle size of the fine iron material from a first particle size to a second particle size includes one or more of jaw crushing, hammer milling, gyratory milling, and grinding by a parallel plate type pulverizer.

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