Electrolyte Formulations and Additives for Iron Anode Electrochemical Systems

Abstract

Various embodiments of the system, method, and device include using tin and / or antimony as additives to the electrolyte and / or electrodes in an electrochemical system, such as a battery, having an iron-based anode. In some embodiments, the addition of tin and / or antimony can improve the cyclability of the iron-based anode. Various embodiments of the system, method, and device include using a high hydroxide concentration electrolyte in an electrochemical system, such as a battery. In some embodiments, the high hydroxide concentration electrolyte may increase the amount of storage charge stored in the cell (i.e., the capacity of the battery material) and / or reduce the overvoltage of the battery (i.e., increase the voltage).

Description

[Technical field]

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 181,757, entitled “ELECTROLYTE FORMULATIONS AND ADDITIVES FOR IRON ANODE ELECTROCHEMICAL SYSTEMS,” filed April 29, 2021, the contents of which are incorporated by reference in their entirety and for all purposes. [Background technology]

[0002] Energy storage technologies are playing an increasingly important role in the power grid. At the most basic level, these energy storage assets provide smoothing to better match generation and demand in the grid. The services performed by energy storage devices benefit the power grid over multiple timescales, from milliseconds to years. Today, energy storage technologies exist that can support timescales from milliseconds to hours, but long-term and ultra-long-term (collectively, >8 hours) energy storage systems are needed.

[0003] Iron-based anode electrochemical systems (or the alternative iron-based anode electrochemical systems described above) are an attractive option for electrochemical energy storage. However, achieving high performance with iron-based anodes can be challenging, especially at low discharge rates, e.g., discharge rates where the full charge time is greater than about 8 hours, e.g., 8 hours, >8 hours, 8-16 hours, 16 hours, >16 hours, 16-24 hours, 24 hours, >24 hours, 24-30 hours, 30 hours, >30 hours, etc. Direct reduced iron ("DRI") is an excellent candidate for an iron-based anode because of the cost of DRI, but electrodes made from DRI can face challenges in achieving improved performance despite the promising material properties of DRI.

[0004] Iron-based alkaline electrochemical systems are an attractive option for long-term energy storage at grid scale due to the low rights cost of iron and alkaline electrolyte components. However, iron-based materials suffer from several drawbacks in alkaline electrolytes, particularly competition with the hydrogen evolution reaction and self-discharge. In addition, grid-scale energy storage requires the use of lower cost, and therefore potentially lower purity, raw materials than traditional iron electrode materials. As a result, cycling iron electrode materials can be difficult, especially the metallic iron-iron hydroxide reaction (step 1 reaction). In most iron electrode systems, this step 1 reaction can be crucial to achieving high round-trip efficiency of the battery.

[0005] Therefore, there is a need for improvements in the design and composition of electrochemical systems having iron-based materials, such as iron-based anodes, to improve the performance of the systems.

[0006] This "Background" section is intended to introduce various aspects of the art that may be related to embodiments of the present invention. As such, the discussion above in this section is intended to provide a framework for better understanding the present invention, and should not be construed as admissions of prior art. Summary of the Invention

[0007] Various embodiments of the systems, methods, and devices include using tin and / or antimony as additives to electrolytes and / or electrodes in electrochemical systems, such as batteries, having iron-based anodes. In some embodiments, the tin and / or antimony can improve the cyclability of the iron-based anodes.

[0008] An embodiment may include a battery including a first electrode including direct reduced iron (DRI) or another sponge iron powder, an electrolyte, and a second electrode, where the first electrode or electrolyte includes an additive containing an element that has low hydrogen evolution reaction (HER) activity and / or improves charging (reduction) of the first electrode. In some embodiments, the element includes tin and / or antimony.

[0009] Various embodiments of the systems, methods, and devices include the use of high hydroxide concentration electrolytes in electrochemical systems such as batteries. In some embodiments, the high hydroxide concentration electrolytes may increase the amount of stored charge stored in the cell (i.e., the capacity of the battery materials) and / or reduce the overpotential of the battery (i.e., increase the voltage).

[0010] An embodiment may include a battery including a first electrode including direct reduced iron (DRI) or another sponge iron powder, an electrolyte including a hydroxide, and a second electrode, the electrolyte further including an additive, the additive including at least one of tin, lead, or antimony. In some embodiments, the total hydroxide concentration in the electrolyte may be about 6M or greater.

[0011] Various embodiments may include alkyl polyglucosides used as co-additives with metal HER inhibitors. Various embodiments may include the incorporation of tin into the current collector. Various embodiments may include the incorporation of tin into sponge iron. Various embodiments may include hydrogen oxidation catalysts and / or hydrogen getters as additives to the anode of an electrochemical cell. Various embodiments may include lignosulfonates used as electrolyte additives and / or anion selective membranes.

[0012] The accompanying drawings, which are incorporated in and constitute a 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 explain the features of the claims. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram of an electrochemical cell according to various embodiments of the present disclosure.

[0014] [Figure 2A] This is a Pourbaix diagram of tin. [Figure 2B] This is a Pourbaix diagram of tin. [Figure 2C] This is a Pourbaix diagram of tin.

[0015] [Diagram 3] Pourbaix diagram of antimony.

[0016] [Figure 4] 1 is a graph showing experimental results of different DRI types using different hydroxide concentrations, according to various embodiments.

[0017] [Diagram 5] FIG. 1 is a graph showing the relationship between the solubility of KOH and temperature.

[0018] [Figure 6] This is a phase diagram for the K2Sn(OH)6-KOH-H2O system at 25.0°C.

[0019] [Figure 7] FIG. 1 illustrates aspects of an electrochemical cell including a lignosulfonate membrane, according to various embodiments.

[0020] [Figure 8] 1A-1D illustrate various exemplary systems in which one or more aspects of various embodiments may be used as part of a bulk energy storage system. [Figure 9] 1A-1D illustrate various exemplary systems in which one or more aspects of various embodiments may be used as part of a bulk energy storage system. [Figure 10]1A-1D illustrate various exemplary systems in which one or more aspects of various embodiments may be used as part of a bulk energy storage system. [Figure 11] 1A-1D illustrate various exemplary systems in which one or more aspects of various embodiments may be used as part of a bulk energy storage system. [Figure 12] 1A-1D illustrate various exemplary systems in which one or more aspects of various embodiments may be used as part of a bulk energy storage system. [Figure 13] 1A-1D illustrate various exemplary systems in which one or more aspects of various embodiments may be used as part of a bulk energy storage system. [Figure 14] 1A-1D illustrate various exemplary systems in which one or more aspects of various embodiments may be used as part of a bulk energy storage system. [Figure 15] 1A-1D illustrate various exemplary systems in which one or more aspects of various embodiments may be used as part of a bulk energy storage system. [Figure 16] 1A-1D illustrate various exemplary systems in which one or more aspects of various embodiments may be used as part of a bulk energy storage system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or similar parts. References to specific examples and implementations are for illustrative purposes only and are not intended to limit the scope of the claims. The following description of embodiments of the invention is not intended to limit the invention to such embodiments, but rather to enable one of ordinary skill in the art to make and use the invention. Unless otherwise noted, the accompanying drawings are not drawn to scale.

[0022] As used herein, unless otherwise specified, room temperature is 25° C. and standard temperature and pressure are 25° C. and 1 atmosphere. Unless expressly stated otherwise, all tests, test results, physical properties, and values ​​that are temperature dependent, pressure dependent, or both, are provided at standard ambient temperature and pressure.

[0023] In general, the term "about," as used herein, unless otherwise specified, is meant to encompass a variation or range of ±10%, the experimental or instrumental error associated with obtaining a stated value, preferably whichever is greater.

[0024] As used herein, unless otherwise stated, recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise stated herein, each individual value within a range is incorporated herein as if it were individually recited herein.

[0025] As used herein, unless otherwise specified, the terms "%", "weight % (abbreviated wt%)", and "mass %" are used interchangeably and refer to the weight of a first component as a percentage of the weight of a total, e.g., formulation, mixture, particle, pellet, agglomerate, material, structure, or product. As used herein, unless otherwise specified, "volume %" and "% volume" and similar such terms refer to the volume of a first component as a percentage of the volume of a total, e.g., formulation, mixture, particle, pellet, agglomerate, material, structure, or product.

[0026] As used herein, unless otherwise specified, the term "molar" (abbreviated "M") is used to refer to molar concentration, also called molarity, and is defined as the number of moles per liter of a substance in solution. For example, a substance at a concentration of 1 mol / L in solution is referred to herein as 1M or a concentration of 1M. Similarly, 1 millimolar (mM) is used herein to mean one thousandth of a mole per liter.

[0027] It should be noted that it is not necessary to provide or express the theory underlying the novel and innovative process, material, performance, or other beneficial features and characteristics that are the subject of or associated with embodiments of the present invention. Nevertheless, various theories are provided herein to further advance the art in the field. The theories presented herein are not intended to limit, restrict, or narrow in any way the scope of protection afforded to the claimed invention unless expressly stated otherwise. Such theories may not be necessary or practiced to utilize the present invention. Furthermore, it is understood that the present invention may be coupled with new and previously unknown theories to explain the function-characteristics of embodiments of the methods, articles, materials, devices, and systems of the present invention. Such subsequently developed theories shall not limit the scope of protection afforded to the present invention.

[0028] The various embodiments of the systems, facilities, 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 facilities or activities that may be developed in the future and with existing facilities or activities that may be modified in part based on the teachings herein. Furthermore, the various embodiments and examples shown herein can be used with each other, in whole or in part, and in various different combinations. Thus, the configurations provided in the various embodiments herein can be used with each other. For example, elements of an embodiment having A, A', and B, and elements of an embodiment having A", C, and D can be used with each other in various combinations, such as A, C, D, and A, A", C, and D, in accordance with the teachings herein. Thus, the scope of protection given to the present invention should not be limited to the specific embodiments, configurations, or arrangements shown in the specific embodiments, examples, or in the specific illustrated embodiments.

[0029] As used herein, unless otherwise specified, the term "specific gravity", also called apparent density, should be given the broadest possible meaning and is generally intended to mean the weight per unit volume of a structure, e.g., a volumetric form of a material. This property will include the internal porosity of the particle as a fraction of its volume. It can be measured, among other techniques, with a low viscosity fluid that wets the particle surface.

[0030] As used herein, unless otherwise specified, the term "actual density," which may also be referred to as true density, should be given the broadest possible meaning and generally refers to the weight per unit volume of a material if no voids were present in that material. This measurement and characterization essentially excludes internal porosity from the material, e.g., does not include any voids in the material.

[0031] Therefore, a collection of porous foam balls (e.g., Nerf® balls) can be used to illustrate the relationship between the three density properties: The weight of the ball filling a container would be the bulk density of the ball.

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[0032] The weight of a single ball per spherical volume of the ball would be its apparent density.

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[0033] The weight of the material that makes up the ball's skeleton, i.e., with all void volume removed, per remaining volume of that material would be the skeleton density.

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[0034] As used herein, unless otherwise specified, the terms agglomerate and aggregate should be given the broadest possible meaning and generally refer to an aggregation of powder-like particles.

[0035] The following examples are provided to illustrate various embodiments of the present systems and methods of the present invention. Such examples are intended to be illustrative and may be prophetic, and should not be considered limiting or in any way limit the scope of the present invention.

[0036] Various embodiments are discussed regarding the use of direct reduced iron (DRI) as a battery (or cell) material, as a battery (or cell) component, and combinations and variations thereof. In various embodiments, DRI may be produced from or may be material resulting from the reduction of natural or processed iron ore 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 may be spherical or substantially spherical. In various embodiments, DRI may be porous and may contain open and / or closed internal pores. In various embodiments, DRI may include material that has been further processed by hot or cold briquetting. In various embodiments, DRI is produced by reducing iron ore pellets to produce ferrous metal (Fe 0 DRI can be produced by forming more metallic (more reduced, less oxidized) materials such as reduced iron ore taconite, wustite (FeO), or composite pellets containing iron metal and residual oxide phases. In various non-limiting embodiments, DRI may be reduced iron ore taconite, direct reduced ("DR") taconite, reduced "blast furnace (BF) grade" pellets, reduced "electric arc furnace (EAF) grade" pellets, "cold direct reduced iron (CDRI)" pellets, direct reduced iron ("DRI") pellets, hot briquetted iron (HBI), or any combination thereof. In the steel and iron industry, DRI is sometimes referred to as "sponge iron" and its use is particularly common in India.

[0037]

[0023] An embodiment of an iron material, including exemplary embodiments of a DRI material for use in various embodiments described herein, including for use as an electrode material, may have one, more than one, or all of the material properties as set forth in Table 1 below. As used herein, including in Table 1, the following terms have the following meanings unless expressly stated otherwise: "specific surface area" means the total surface area of ​​a material per unit mass, including the surface area of ​​pores in a porous structure; "carbon content" or "carbon (wt%)" means the mass of total carbon as a percentage of the total mass of the DRI; "cementite content" or "cementite (wt%)" means the mass of FeC as a percentage of the total mass of the DRI; "total Fe (wt%)" means the mass of all iron as a percentage of the total mass of the DRI; "metallic Fe (wt%)" means the mass of FeC as a percentage of the total mass of the DRI. 0 "Metallization" means the mass of iron in the Fe state as a percentage of the total mass of iron. 0 As used herein, weight and volume percentages and apparent densities are understood to exclude any electrolyte infiltrating the pores or any transient additives within the pores, unless otherwise stated. [Table 1]

[0038] * The specific surface area is preferably determined by the Brunauer-Emmett-Teller adsorption method ("BET"), more preferably BET as set forth in ISO 9277, the disclosure of which is incorporated herein by reference in its 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 be used to obtain results that can be correlated with the BET results.

[0039] **Actual density is preferably determined by helium (He) pycnometer method, more preferably as set forth in ISO 12154, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests can be used to obtain results that can be correlated with He pycnometer results. Actual density is sometimes also referred to in the art as "true density" or "skeletal density."

[0040] *** Apparent density is preferably determined by immersion in water, more preferably as set forth in ISO 15968, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests can be used to obtain results that can be correlated with He pycnometer results. Porosity can be defined as the ratio of apparent density to actual density.

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[0041] **** d 孔、90%容積 is preferably determined by mercury (Hg) intrusion porosimetry, more preferably as set forth in ISO 15901-1, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as gas adsorption, can be used to provide results that can be correlated with Hg intrusion results. 孔、90%容積 is the pore diameter above which 90% of the total pore volume resides.

[0042] ***** d 孔、50%表面積 is preferably determined by mercury (Hg) intrusion porosimetry, more preferably as set forth in ISO 15901-1, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as gas adsorption, can be used to provide results that can be correlated with Hg intrusion results. 孔、50%表面積 is the pore diameter above which 50% of the free surface area lies.

[0043] #Total Fe (wt%) is preferably determined by dichromate titration, more preferably as set forth in ASTM E246-10, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as tin(II) chloride reduction titration, titanium(III) chloride reduction titration, and inductively coupled plasma (ICP) spectroscopy, can be used to obtain results that can be correlated to the dichromate titration.

[0044] ##Metallic Fe (wt%) is preferably determined by iron(III) chloride titration, more preferably as set forth in ISO 16878, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as bromine-methanol titration, can be used to obtain results that can be correlated to iron(III) chloride titration.

[0045] ### Metallization (%) is preferably determined by the ratio of metallic Fe to total Fe, each preferably determined by the methods described above.

[0046] ####Carbon (wt%) is preferably determined by infrared absorption after firing in an induction furnace, and more preferably as set forth in ISO 9556, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as various combustion and inert gas fusion techniques, such as those set forth in ASTM E1019-18, can be used to produce results that can be correlated to infrared absorption after firing in an induction furnace.

[0047] #####Fe 2+ (wt %) is preferably determined by titration, and more preferably as set forth in ASTM D3872-05, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as Mössbauer spectroscopy, X-ray absorption spectroscopy, and the like, can be used to provide results that can be correlated to the titration method.

[0048] $Fe 3+ (wt%) is preferably total Fe (wt%), metallic Fe (wt%), Fe 2+ (wt%), and Fe 3+ It is determined by the mass balance relationship between or within these (wt%). Specifically, total Fe (wt%) = metallic Fe (wt%) + Fe 2+ (Weight%)+Fe 3+ (wt%) must be true due to the law of conservation of mass; therefore, Fe 3+ (wt%) is Fe 3+ (wt%) = total Fe (wt%) - metallic Fe (wt%) - Fe 2+ It can be calculated as a percentage by weight.

[0049] $$SiO2 (wt%) is preferably determined gravimetrically, more preferably as set forth in ISO 2598-1, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as reduced molybdosilicate spectrophotometry, X-ray diffraction (XRD), etc., can be used to obtain results that can be correlated to gravimetric methods. In certain methods, SiO2 wt% is not determined directly, rather the Si concentration (including neutral and ionic species) is measured and SiO2 wt% is calculated assuming SiO2 stoichiometry, i.e., a molar ratio of Si:O is assumed to be 1:2.

[0050] $$$Ferrite (wt%, XRD) is preferably determined by X-ray diffraction (XRD).

[0051] $$$$Wüstite (FeO, wt%, XRD) is preferably determined by X-ray diffraction (XRD).

[0052] $$$$$Goethite (FeOOH, wt%, XRD) is preferably determined by X-ray diffraction (XRD).

[0053] + Cementite (Fe3C, wt%, XRD) is preferably determined by X-ray diffraction (XRD).

[0054] Additionally, embodiments of ferrous materials, including, for example, embodiments of DRI materials, for use in various embodiments described herein, including for use as an electrode material, may have one or more of the following properties, characteristics, or features, as shown in Table 1A (note that values ​​in a row or a column may be present with values ​​in different rows or columns): [Table 1A]

[0055] Total Fe (wt%) is preferably determined by dichromate titration, more preferably as set forth in ASTM E246-10, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as tin(II) chloride reduction titration, titanium(III) chloride reduction titration, and inductively coupled plasma (ICP) spectroscopy, can be used to obtain results that can be correlated to the dichromate titration.

[0056] !!SiO2 (wt%) is preferably determined gravimetrically, more preferably as set forth in ISO2598-1, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as reduced molybdosilicate spectrophotometry, X-ray diffraction (XRD), etc., can be used to obtain results that can be correlated to 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 assuming SiO2 stoichiometry. That is, it is assumed that the molar ratio of Si:O is 1:2.

[0057] !!!Al2O3 (wt%) is preferably determined by flame atomic absorption spectrometry, more preferably as set forth in ISO 4688-1, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as X-ray diffraction (XRD), may be used to obtain results that can be correlated to flame atomic absorption spectrometry. In certain methods, Al2O3 wt% is not determined directly, rather the Al concentration (including neutral and ionic species) is measured and Al2O3 wt% is calculated assuming Al2O3 stoichiometry, i.e., a molar ratio of Al:O is assumed to be 2:3.

[0058] !!!!MgO (wt%) is preferably determined by flame atomic absorption spectrometry, more preferably as set forth in ISO 10204, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as X-ray diffraction (XRD), may be used to obtain results that can be correlated to flame atomic absorption spectrometry. In certain methods, MgO wt% is not determined directly, rather the Mg concentration (including neutral and ionic species) is measured and the MgO wt% is calculated assuming MgO stoichiometry, i.e., a 1:1 molar ratio of Mg:O is assumed.

[0059] !!!!!CaO (wt%) is preferably determined by flame atomic absorption spectrometry, more preferably as set forth in ISO 10203, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as X-ray diffraction (XRD), may be used to obtain results that can be correlated to flame atomic absorption spectrometry. In certain methods, CaO wt% is not determined directly, rather the Ca concentration (including neutral and ionic species) is measured and CaO wt% is calculated assuming CaO stoichiometry, i.e., a 1:1 molar ratio of Ca:O is assumed.

[0060] &TiO2 (wt%) is preferably determined by diantipyrylmethane spectrophotometry, more preferably as set forth in ISO 4691, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as X-ray diffraction (XRD), can be used to obtain results that can be correlated to diantipyrylmethane spectrophotometry. In certain methods, TiO2 wt% is not determined directly, rather the Ti concentration (including neutral and ionic species) is measured and TiO2 wt% is calculated assuming TiO2 stoichiometry, i.e., a molar ratio of Ti:O is assumed to be 1:2.

[0061] && Actual density is preferably determined by helium (He) pycnometer method, more preferably as set forth in ISO 12154, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests can be used to obtain results that can be correlated with He pycnometer results. Actual density is sometimes also referred to in the art as "true density" or "skeletal density."

[0062] &&& Apparent density is preferably determined by immersion in water, more preferably as set forth in ISO 15968, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests may be used to obtain results that can be correlated with He pycnometer results.

[0063] &&&&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, more preferably as set forth in Method 2 of ISO 3852, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests can be used to obtain results that can be correlated with the results of the gravimetric method.

[0064] &&&&&Porosity is preferably determined by the ratio of apparent density to actual density.

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[0065] Also, the properties shown in Table 1 may be present in embodiments along with, in addition to, or instead of the properties in Table 1A, and greater and lesser values ​​of such properties may be present in various embodiments.

[0066] In an embodiment, the specific surface area of ​​the pellet is about 0.05 m 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 / g, and about 1m 2 / g, and is about 2m 2 / g, about 5m 2 / g, and may be less than about 15m 2 / g, and may be less than about 20m 2 / g, as well as combinations and variations thereof, and larger and smaller values.

[0067] Generally, iron ore pellets are produced by crushing, grinding, or milling iron ore into a fine powder-like form, which is then concentrated (concentrated) by removing impurity phases (so-called "gangue") liberated by the grinding operation. Generally, grinding the ore to finer (smaller) particle sizes increases the purity of the resulting concentrate. The concentrate is then formed into pellets by a pelletizing or balling process (e.g., using a drum or disk pelletizer). Generally, more energy input is required to produce higher purity ore pellets. Iron ore pellets are generally commercially or sold in two main categories: blast furnace (BF) grade pellets and direct reduction (DR grade), sometimes also called electric arc furnace (EAF) grade, with the main difference being the content of SiO2 and other impurity phases, which are higher in BF grade pellets compared to DR grade pellets. Typical critical specifications for DR grade pellets or feedstock are a total Fe content by mass in the range of 63-69 wt%, such as 67 wt%, and a SiO2 content by mass of less than 3 wt%, such as 1 wt%. Typical critical specifications for BF grade pellets or feedstock are a total Fe content by mass in the range of 60-67 wt%, such as 63 wt%, and a SiO2 content by mass in the range of 2-8 wt%, such as 4 wt%.

[0068] In certain embodiments, DRI can be produced by the reduction of "blast furnace" pellets, in which case the resulting DRI may have material properties as set forth below in Table 2. The use of reduced BF grade DRI can be advantageous because less input energy is required to produce the pellets, which translates into a lower cost finished product. [Table 2]

[0069] *The specific surface area is preferably determined by the Brunauer-Emmett-Teller adsorption method ("BET"), more preferably BET as set forth in ISO 9277, the disclosure of which is incorporated herein by reference in its 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 be used to obtain results that can be correlated with the BET results.

[0070] ** Actual density is preferably determined by helium (He) pycnometer method, more preferably as set forth in ISO 12154, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests can be used to obtain results that can be correlated with He pycnometer results. Actual density is sometimes also referred to in the art as "true density" or "skeletal density."

[0071] *** Apparent density is preferably determined by immersion in water, more preferably as set forth in ISO 15968, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests can be used to obtain results that can be correlated with He pycnometer results. Porosity can be defined as the ratio of apparent density to actual density.

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[0072] **** d 孔、90%容積 is preferably determined by mercury (Hg) intrusion porosimetry, more preferably as set forth in ISO 15901-1, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as gas adsorption, can be used to provide results that can be correlated with Hg intrusion results. 孔、90%容積is the pore diameter above which 90% of the total pore volume resides.

[0073] ***** d 孔、50%表面積 is preferably determined by mercury (Hg) intrusion porosimetry, more preferably as set forth in ISO 15901-1, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as gas adsorption, can be used to provide results that can be correlated with Hg intrusion results. 孔、50%表面積 is the pore diameter above which 50% of the free surface area lies.

[0074] #Total Fe (wt%) is preferably determined by dichromate titration, more preferably as set forth in ASTM E246-10, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as tin(II) chloride reduction titration, titanium(III) chloride reduction titration, and inductively coupled plasma (ICP) spectroscopy, can be used to obtain results that can be correlated to the dichromate titration.

[0075] ##Metallic Fe (wt%) is preferably determined by iron(III) chloride titration, more preferably as set forth in ISO 16878, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as bromine-methanol titration, can be used to obtain results that can be correlated to iron(III) chloride titration.

[0076] ### Metallization (%) is preferably determined by the ratio of metallic Fe to total Fe, each preferably determined by the methods described above.

[0077] ####Carbon (wt%) is preferably determined by infrared absorption after firing in an induction furnace, and more preferably as set forth in ISO 9556, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as various combustion and inert gas fusion techniques, such as those set forth in ASTM E1019-18, can be used to produce results that can be correlated to infrared absorption after firing in an induction furnace.

[0078] #####Fe 2+ (wt %) is preferably determined by titration, and more preferably as set forth in ASTM D3872-05, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as Mössbauer spectroscopy, X-ray absorption spectroscopy, and the like, can be used to provide results that can be correlated to the titration method.

[0079] Fe 3+ (wt%) is preferably total Fe (wt%), metallic Fe (wt%), Fe 2+ (wt%), and Fe 3+ It is determined by the mass balance relationship between or within these (wt%). Specifically, total Fe (wt%) = metallic Fe (wt%) + Fe 2+ (Weight%)+Fe 3+ (wt%) must be true due to the law of conservation of mass; therefore, Fe 3+ (wt%) is Fe 3+ (wt%) = total Fe (wt%) - metallic Fe (wt%) - Fe 2+ It can be calculated as a percentage by weight.

[0080] $$SiO2 (wt%) is preferably determined gravimetrically, more preferably as set forth in ISO 2598-1, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as reduced molybdosilicate spectrophotometry, X-ray diffraction (XRD), etc., can be used to obtain results that can be correlated to gravimetric methods. In certain methods, SiO2 wt% is not determined directly, rather the Si concentration (including neutral and ionic species) is measured and SiO2 wt% is calculated assuming SiO2 stoichiometry, i.e., a molar ratio of Si:O is assumed to be 1:2.

[0081] $$$Ferrite (wt%, XRD) is preferably determined by X-ray diffraction (XRD).

[0082] $$$$Wüstite (FeO, wt%, XRD) is preferably determined by X-ray diffraction (XRD).

[0083] $$$$$Goethite (FeOOH, wt%, XRD) is preferably determined by X-ray diffraction (XRD).

[0084] + Cementite (Fe3C, wt%, XRD) is preferably determined by X-ray diffraction (XRD).

[0085] Also, the properties shown in Table 2 may be present in embodiments along with, in addition to, or instead of the properties in Table 1 and / or Table 1A, and greater and lesser values ​​of such properties may be present in various embodiments.

[0086] In certain embodiments, the DRI can be produced by reduction of DR grade pellets, where the resulting DRI can have material properties as set forth below in Table 3. The use of reduced DR grade DRI can be advantageous due to the higher Fe content in the pellets, thereby increasing the energy density of the battery. [Table 3]

[0087] * The specific surface area is preferably determined by the Brunauer-Emmett-Teller adsorption method ("BET"), more preferably BET as set forth in ISO 9277, the disclosure of which is incorporated herein by reference in its 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 be used to obtain results that can be correlated with the BET results.

[0088] ** Actual density is preferably determined by helium (He) pycnometer method, more preferably as set forth in ISO 12154, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests can be used to obtain results that can be correlated with He pycnometer results. Actual density is sometimes also referred to in the art as "true density" or "skeletal density."

[0089] *** Apparent density is preferably determined by immersion in water, more preferably as set forth in ISO 15968, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests can be used to obtain results that can be correlated with He pycnometer results. Porosity can be defined as the ratio of apparent density to actual density.

number

[0090] **** d 孔、90%容積is preferably determined by mercury (Hg) intrusion porosimetry, more preferably as set forth in ISO 15901-1, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as gas adsorption, can be used to provide results that can be correlated with Hg intrusion results. 孔、90%容積 is the pore diameter above which 90% of the total pore volume resides.

[0091] ***** d 孔、50%表面積 is preferably determined by mercury (Hg) intrusion porosimetry, more preferably as set forth in ISO 15901-1, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as gas adsorption, can be used to provide results that can be correlated with Hg intrusion results. 孔、50%表面積 is the pore diameter above which 50% of the free surface area lies.

[0092] #Total Fe (wt%) is preferably determined by dichromate titration, more preferably as set forth in ASTM E246-10, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as tin(II) chloride reduction titration, titanium(III) chloride reduction titration, and inductively coupled plasma (ICP) spectroscopy, can be used to obtain results that can be correlated to the dichromate titration.

[0093] ##Metallic Fe (wt%) is preferably determined by iron(III) chloride titration, more preferably as set forth in ISO 16878, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as bromine-methanol titration, can be used to obtain results that can be correlated to iron(III) chloride titration.

[0094] ### Metallization (%) is preferably determined by the ratio of metallic Fe to total Fe, each preferably determined by the methods described above.

[0095] ####Carbon (wt%) is preferably determined by infrared absorption after firing in an induction furnace, and more preferably as set forth in ISO 9556, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as various combustion and inert gas fusion techniques, such as those set forth in ASTM E1019-18, can be used to produce results that can be correlated to infrared absorption after firing in an induction furnace.

[0096] #####Fe 2+ (wt %) is preferably determined by titration, and more preferably as set forth in ASTM D3872-05, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as Mössbauer spectroscopy, X-ray absorption spectroscopy, and the like, can be used to provide results that can be correlated to the titration method.

[0097] $Fe 3+ (wt%) is preferably total Fe (wt%), metallic Fe (wt%), Fe 2+ (wt%), and Fe 3+ It is determined by the mass balance relationship between or within these (wt%). Specifically, total Fe (wt%) = metallic Fe (wt%) + Fe 2+ (Weight%)+Fe 3+ (wt%) must be true due to the law of conservation of mass; therefore, Fe 3+ (wt%) is Fe 3+ (wt%) = total Fe (wt%) - metallic Fe (wt%) - Fe 2+ It can be calculated as a percentage by weight.

[0098] $$SiO2 (wt%) is preferably determined gravimetrically, more preferably as set forth in ISO 2598-1, the disclosure of which is incorporated herein by reference in its entirety. It is recognized that other tests, such as reduced molybdosilicate spectrophotometry, X-ray diffraction (XRD), etc., can be used to obtain results that can be correlated to gravimetric methods. In certain methods, SiO2 wt% is not determined directly, rather the Si concentration (including neutral and ionic species) is measured and SiO2 wt% is calculated assuming SiO2 stoichiometry, i.e., a molar ratio of Si:O is assumed to be 1:2.

[0099] $$$Ferrite (wt%, XRD) is preferably determined by X-ray diffraction (XRD).

[0100] $$$$Wüstite (FeO, wt%, XRD) is preferably determined by X-ray diffraction (XRD).

[0101] $$$$$Goethite (FeOOH, wt%, XRD) is preferably determined by X-ray diffraction (XRD).

[0102] + Cementite (Fe3C, wt%, XRD) is preferably determined by X-ray diffraction (XRD).

[0103] Also, the properties shown in Table 3 may be present in an embodiment along with, in addition to, or instead of the properties in Tables 1, 1A, and / or 2. Also, greater and lesser values ​​of such properties may be present in various embodiments.

[0104] Electrochemical cells, such as batteries, store electrochemical energy by using the difference in electrochemical potential to create a voltage difference between the positive and negative electrodes. When the electrodes are connected by a conductive element, this voltage difference produces an electric current. In a battery, the negative and positive electrodes are connected in series by an external and an internal resistive element. Generally, the external element conducts electrons and the internal element (the electrolyte) conducts ions. Since no charge imbalance is allowed between the negative and positive electrodes, the two must supply ions and electrons at the same rate. In operation, the electronic current can be used to power an external device. Rechargeable batteries can be charged by applying an opposing voltage difference, which manipulates the current and ion flow in the opposite direction to the battery discharging during operation.

[0105] Embodiments of the present invention include devices, systems, and methods for long-term and ultra-long-term low-cost energy storage. As used herein, "long-term" and / or "ultra-long-term" may refer to energy storage periods of 8 hours or more, such as an 8-hour energy storage period, an energy storage period ranging from 8 hours to 20 hours, an energy storage period ranging from 20 hours to 24 hours, an energy storage period ranging from 24 hours to 1 week, an energy storage period ranging from 1 week to 1 year (e.g., from days to weeks to months). In other words, "long-term" and / or "ultra-long-term" energy storage cells refer to electrochemical cells that may be configured to store energy for days, weeks, or seasons. For example, an electrochemical cell may be configured to store energy generated by a solar cell during summer months when sunlight is abundant and solar power generation exceeds power grid needs, and discharge the stored energy during winter months when sunlight may be insufficient to meet power grid needs.

[0106] Generally, in an embodiment, the long-term energy storage cell may be a long-term electrochemical cell. Generally, this long-term electrochemical cell can store electricity generated in the power generation system when: (i) the power source or fuel for the generation is available, abundant, cheap, and combinations and variations thereof; (ii) the power needs or demands of the grid, customer, or other users are less than the amount of electricity generated by the power generation system, the price paid to provide such electricity to the grid, customer, or other users is below the economically efficient point for generating such electricity (e.g., the generation cost 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, customer, or other users when it is economical or otherwise needed. For example, the electrochemical cell may be configured to store energy generated by solar cells during summer months when sunlight is abundant and solar power generation exceeds power grid needs, and to discharge the stored energy during winter months when sunlight may be insufficient to meet power grid needs.

[0107] According to other embodiments, the invention includes devices, systems, and methods for storing energy for short durations of less than about 8 hours. For example, the electrochemical cells may be configured to store energy generated by the solar cells during a diurnal cycle when solar generation exceeds grid needs at noon, and release the stored energy later in the evening when sunlight may be insufficient to meet grid needs. As another example, the invention includes energy storage for use as a backup power source when electricity provided by the grid is insufficient in facilities such as homes, commercial buildings, factories, hospitals, or data centers where required discharge times vary from a few minutes to a few days.

[0108] In some embodiments, an electrochemical cell includes a negative electrode, a positive electrode, an electrolyte, and a separator disposed between the positive and negative electrodes (e.g., as shown in FIG. 1). FIG. 1 illustrates an example of an electrochemical cell 100, such as a battery, including a negative electrode and electrolyte 102 separated from a positive electrode and electrolyte 103 by a separator 104. The separator 104 may be supported by a polypropylene mesh 105 and a polyethylene frame 108 of the cell 100. Current collectors 107 may be attached to each of the negative electrode 102 and positive electrode 103 and supported by a polyethylene backing plate 106. In some embodiments, the temperature of the electrochemical cell 100 may be controlled, such as by insulation around the cell 100 and / or a heater 150. For example, the heater 150 may increase the temperature of the cell 100 and / or certain components of the cell, such as the electrolytes 102, 103. The configuration of the electrochemical cell 100 in FIG. 1 is merely an example of one electrochemical cell configuration according to various embodiments and is not intended to be limiting. Other configurations, such as electrochemical cells with different types of meshes and / or without polypropylene mesh 105, electrochemical cells with different types of frames and / or without polyethylene frames 108, electrochemical cells with different types of current collectors and / or without current collectors, electrochemical cells with different types of backing plates and / or without polyethylene backing plates 106, electrochemical cells with different types of insulators and / or without insulators, electrochemical cells with different types of heaters and / or without heaters 150, may be substituted for the example configuration of electrochemical cell 100 shown in FIG. 1 , and other configurations are in accordance with various embodiments.

[0109] In some embodiments, multiple electrochemical cells 100 of Figure 1 may be electrically connected in series to form a stack. In certain other embodiments, multiple electrochemical cells 100 may be electrically connected in parallel. In certain other embodiments, multiple electrochemical cells 100 are connected in a mixed series-parallel electrical configuration to provide a preferred combination of current and voltage.

[0110] According to various embodiments, the anode is comprised of pelletized, briquette, pressed, or sintered iron-bearing compounds. Such iron-bearing compounds may contain one or more forms of iron ranging from highly reduced (more metallic) to highly oxidized (more ionic) iron. In various embodiments, the pellets may contain various iron compounds such as iron oxide, iron hydroxide, iron sulfide, iron carbide, or combinations thereof. In various embodiments, the anode may be sintered iron agglomerates having various shapes. In some embodiments, atomized iron powder or sponge iron powder may be used as a feed material to form the sintered iron electrode. In some embodiments, the green body may further include a binder such as a polymer or an inorganic clay-like material. In various embodiments, the agglomerated sintered iron pellets may be formed in a furnace such as a continuous feed calcining furnace, a batch feed calcining furnace, a blast furnace, a rotary calcining furnace, or a rotary hearth. In various embodiments, the pellets may include a form of reduced and / or sintered iron-bearing precursor known to those skilled in the art as direct reduced iron (DRI) and / or its by-product materials. Various embodiments may include processing the pellets, including DRI pellets, using electrical, electrochemical, mechanical, chemical, and / or thermal processes prior to introducing the pellets into an electrochemical cell.

[0111] According to various embodiments, an electrochemical cell, such as cell 100 of FIG. 1, includes a negative electrode (also called an anode), a positive electrode (also called a cathode), and an electrolyte. The negative electrode may be a ferrous material. The electrolyte may be an aqueous solution. In certain embodiments, the electrolyte may be an alkaline solution (pH>10). In certain embodiments, the electrolyte may be a near-neutral solution (10>pH>4).

[0112] In one example, the half-cell reactions at the negative electrode during discharge and oxidation in an alkaline electrolyte are: Step 1) Fe + 2OH -←→Fe(OH)2+2e - ; and step 2) 3Fe(OH)2 + 2OH - ←→Fe3O4+4H2O+2e - In step 1, iron hydroxide may form on the surface of the iron forming the anode. In step 2, the iron hydroxide is further oxidized to form magnetite. Upon discharge, there is a net volume increase, which is incorporated into the porosity of the anode. The theoretical capacity based on metallic iron from the anode reaction in this example is 960 mAh / gFe in step 1 and 320 mAh / gFe in step 2.

[0113] Iron-based electrodes (also called Fe anodes) are difficult to recharge because of competition with hydrogen (H2) evolution. Hydrogen evolution is a side reaction that does not lead to recharging the battery because electrons are diverted to H2 instead of being stored in the more reduced iron-bearing anode. Additionally, the ability of electrons to move through the anode can also impede the charge and discharge reactions. If there is no or limited pathway for electrons to move through the anode, the anode may charge and discharge less efficiently. Another issue that can impede recharging of iron-based electrodes is pore clogging. In some cases, methods to increase the surface area of ​​iron-based anodes can also lead to clogging of the anode pores. When the anode pores are clogged, ions cannot enter or leave the anode, and the anode cannot be recharged. This clogging, combined with the difficulty of recharging the Fe anode, leads to a significant loss of specific discharge capacity.

[0114] In various embodiments, one or more additives, such as lead (Pb), tin (Sn), antimony (Sb), copper (Cu), silver (Ag), gold (Au), etc., may be added to the electrochemical cell. The addition of one or more additives according to various embodiments may improve charging of an iron-based negative electrode (Fe anode). In various embodiments, the one or more additives may include an element that has a low hydrogen evolution reaction (HER) in its metallic form. In various embodiments, the electrochemical cell to which the one or more additives are added may include an electrolyte that includes one or more hydroxides. In various embodiments, the electrochemical cell to which the one or more additives are added may include an electrolyte that does not include hydroxides.

[0115] In various embodiments, additives that inhibit hydrogen evolution, such as metals with low hydrogen evolution reaction (HER) activity (e.g., lead (Pb), tin (Sn), antimony (Sb), etc.), may be added to the electrochemical cell to improve charging of iron-based negative electrodes (Fe anodes). In various embodiments, additives that inhibit hydrogen evolution, such as metals with low hydrogen evolution reaction (HER) activity (e.g., lead (Pb), tin (Sn), antimony (Sb), etc.), may be added to the electrolyte and / or anode of the electrochemical cell.

[0116] An additive with low hydrogen evolution reaction (HER) activity can be defined relative to the HER activity of iron. In a first example, an additive with a lower hydrogen evolution reaction (HER) exchange current density than that of iron can be considered to have low hydrogen evolution reaction (HER) activity. In a second example, a cell containing an additive with low HER activity has a lower rate of hydrogen evolution in the cell compared to a cell without an additive with low HER activity (e.g., as measured by in situ detection of hydrogen evolution). In a third example, a cell containing an additive with low HER activity generates less hydrogen at a given state of charge than a comparable cell without an additive with low HER activity. In one set of examples, a significantly lower HER activity can be a reduction in HER activity of 50% or more. In a further set of examples, a significantly lower hydrogen generation can be a reduction in HER activity of 10% or more.

[0117] The additive with low HER activity may also be defined by the coulombic efficiency of the iron anode-containing cell. The additive with low HER activity causes the coulombic efficiency of the cell to be higher than the coulombic efficiency of a cell containing only the anode material. A significantly higher coulombic efficiency may be ≧5% higher efficiency than a cell containing only the anode material. In various embodiments, the additive with low HER activity may be added to the electrochemical cell in a solid form (e.g., metallic form) and / or in a liquid form.

[0118] In various embodiments, additives that improve the conductive network, such as highly conductive metals (tin (Sn), copper (Cu), silver (Ag), gold (Au)) or derivatives in the iron anode, may be added to the electrochemical cell, thereby improving charging of the iron-based negative electrode (Fe anode). In various embodiments, additives that improve the conductive network, such as highly conductive metals (tin (Sn), copper (Cu), silver (Ag), gold (Au)) or derivatives in the iron, may be added to the electrolyte and / or anode of the electrochemical cell. The highly conductive metal may be a metallic element having an electrical resistance of less than 125 nanoohm·meter (nΩ·m).

[0119] In various embodiments, tin (Sn) and / or tin-containing compounds may be included (e.g., added, present, etc.) in the electrochemical cell, for example, in the electrolyte, as part of an electrode, as a reservoir in the electrochemical cell, etc. The inclusion of tin and / or tin-containing compounds can reduce the tendency for hydrogen evolution at the iron anode, thereby facilitating a more efficient recharge of the iron electrode. That is, upon recharge, more of the step 1 reaction volume is reversed and more metallic iron is available in the charged state. This results in a larger step 1 reaction volume in the subsequent discharge step. Without being bound to a particular scientific interpretation or a particular theory of operation, it is believed that the increase in hydrogen evolution overpotential may result from the deposition of tin on the iron anode, resulting in a reduced HER activity of the iron anode compared to the HER activity in the absence of tin. The reduced HER activity may also result from alloying, formation of surface phases, or complexation of tin with the iron anode material. Regardless of the mechanism of action, the above-mentioned advantage of cells containing tin is that the charging efficiency of the iron anode is increased compared to the charging efficiency in the absence of tin. Tin may have high solubility in alkaline solutions (pH>10) electrolytes, and the inclusion of tin and / or tin-containing compounds in the electrolyte may result in the inclusion of tin in the electrolyte used to plate the iron anode. For example, Figure 6 is a phase diagram for the K2Sn(OH)6-KOH-H2O system at 25.0 °C. The black circles in Figure 6 represent the solution composition, and the dark circles represent the wet residue composition. As shown in Figure 6, the maximum solubility at 25.0 °C is 0.272 M K2Sn(OH)6 for 6 M KOH and close to 6 mM K2Sn(OH)6 for 10-13 M OH. The deposition of tin on the iron anode results in the formation of tin in the step 1 reaction volume, i.e., Fe+2OH - ←→Fe(OH)2+2e - increases, which is due to the new phase FeSnO x This inclusion of tin in the iron anode may be due to the formation of FeSn+nOH, which may allow for improved recharging of the iron anode. - ←→FeSnOx+me -, which may lead to a more efficient or altered charging mechanism, improving the overall high potential discharge capacity. The inclusion of tin and / or tin-containing compounds may improve the cyclability of the iron anode in the electrochemical cell. In various embodiments, the tin and / or tin-containing compounds include metallic tin, stannate, and / or any other source of tin. Specific examples include metallic tin (Sn), sodium stannate trihydrate (Na2SnO3·3H2O), potassium stannate trihydrate (K2SnO3·3H2O), tin oxide (SnO2), stannite (Pb3Sn4FeSb2S), and tin oxide (Pb3Sn4FeSb2S). 14 ), copper iron tin sulfide (Cu2FeSnS4), lead-tin alloys (60 / 40 Sn / Pb solder, 63 / 37 Sn / Pb solder, Terne I alloy: 10-20% Sn, balance Pb), zinc-tin alloys (Terne II alloy: 10-20% Sn, balance Zn), or tin sulfides (SnS or SnS2) may be included in the electrochemical cell, for example, in the electrolyte and / or electrodes. In various embodiments, the tin source may be a solid source or a soluble source of tin and / or tin. Figures 2A-2C are Pourbaix diagrams of tin.

[0120] In various embodiments, the tin and / or tin-containing compound may be included as part of the electrolyte of the electrochemical cell. For example, the tin and / or tin-containing compound may be added to the electrolyte in an amount such that the added tin and / or tin-containing compound is present in the electrolyte from about 0.1 millimolar (mM) to the saturation limit of the tin and / or tin-containing compound.As specific examples, tin and / or tin-containing compounds are contained in the electrolyte at concentrations of 0.1 mM, 0.1 mM to 10 mM, 0.1 mM to 100 mM (or 0.1 M), 10 mM, 10 mM to 100 mM (or 0.1 M), 10 mM to 50 mM, 50 mM, 50 mM to 100 mM (or 0.1 M), 100 mM (or 0.1 M), 100 mM (or 0.1 M) to 1 M, 1 M, 100 mM (or 0.1 M) to 750 mM (or 0.75 M), 750 mM (or 0.75 M), 100 mM (or 0.1 M) to 500 mM (or 0.5M), 500mM (or 0.5M), 100mM (or 0.1M) to 600mM (or 0.6M), 600mM (or 0.6M), 100mM (or 0.1M) to 670mM (or 0.67M), 670mM (or 0.67M), 500mM (or 0.5M) to 670mM (or 0.67M), 600mM (or 0.6M) to 670mM (or 0.67M), 650mM (or 0.65M) to 670mM (or 0.67M), 650mM (or 0.65M), 0.1mM to in electrolyte Saturation limit of tin and / or tin-containing compounds, saturation limit of tin and / or tin-containing compounds in electrolytes from 10 mM, saturation limit of tin and / or tin-containing compounds in electrolytes from 50 mM, saturation limit of tin and / or tin-containing compounds in electrolytes from 100 mM (or 0.1 M), saturation limit of tin and / or tin-containing compounds in electrolytes from 500 mM (or 0.5 M), saturation limit of tin and / or tin-containing compounds in electrolytes from 600 mM (or 0.6 M), saturation limit of tin and / or tin-containing compounds in electrolytes from 650 mM (or 0.65 M) ) ~ the saturation limit of tin and / or tin-containing compounds in the electrolyte, 650 mM (or 0.65M) ~ the saturation limit of tin and / or tin-containing compounds in the electrolyte, 670 mM (or 0.67M) ~ the saturation limit of tin and / or tin-containing compounds in the electrolyte, 750 mM (or 0.75M) ~ the saturation limit of tin and / or tin-containing compounds in the electrolyte, less than the saturation limit of tin and / or tin-containing compounds in the electrolyte, the saturation limit of tin and / or tin-containing compounds in the electrolyte, etc.As a further example, tin and / or tin-containing compounds may be added to the electrolyte in an amount such that the added tin and / or tin-containing compounds are from about 0.01% to about 20% by weight of the electrolyte. As specific examples, the tin and / or tin-containing compounds may be present in the electrolyte at 0.01% by weight, 0.01% to 0.1% by weight, 0.1% by weight, 0.01% to 5% by weight, 0.1% to 5% by weight, 0.1% to 20% by weight, 5% by weight, 5% to 20% by weight, 20% by weight, etc.

[0121] In various embodiments, tin and / or tin-containing compounds may be included as part of the anode of an electrochemical cell. For example, tin and / or tin-containing compounds may be incorporated into the anode by mixing with an iron source for the anode, depositing on the surface of the anode, incorporating into the bed of the anode, etc. By way of example, tin and / or tin-containing compounds may be added to the anode in an amount such that the added tin and / or tin-containing compounds are from about 0.1% to about 20% by weight based on the dry weight of the anode (this weight percent figure does not include the electrolyte). As specific examples, tin and / or tin-containing compounds can be present in the anode in an amount of 0.1 wt%, 0.1 wt% to 6 wt%, 0.1 wt% to 1 wt%, about 1 wt%, about 1 wt% to about 3 wt%, about 3 wt%, about 3 wt% to about 6 wt%, about 1 wt% to about 6 wt%, about 6 wt%, 6 wt% to 20 wt%, 0.1 wt% to 5 wt%, 0.1 wt% to 0.5 wt%, about 0.5 wt%, 0.5 wt% to 5 wt%, about 5 wt%, 5 wt% to 6 wt%, 5 wt% to 7 wt%, 6 wt% to 7 wt%, about 7 wt%, about 20 wt%, etc. Further, the tin and / or tin-containing compound may be present in an amount such that the amount of tin incorporated in the anode is, based on the weight of the active material of the anode (e.g., based on the weight of the iron active material of the anode), from about 0.044 weight percent tin to about 20 weight percent tin, e.g., from about 0.044 weight percent tin, 0.044 weight percent tin to 0.1 weight percent tin, from about 0.1 weight percent tin, 0.1 weight percent tin to 6 weight percent tin, 0.1 weight percent tin to 1 weight percent tin, from about 1 weight percent tin, from about 1 weight percent tin to about 3 weight percent tin, or from about 3 weight percent tin. tin, about 3% tin to about 6% tin, about 1% tin to about 6% tin, about 6% tin, 6% tin to 20% tin, 0.1% tin to 5% tin, about 5% tin, 5% tin to 6% tin, 5% tin to 7% tin, 6% tin to 7% tin, about 7% tin, 6% tin to 10% tin, about 10% tin, 10% tin to 20% tin, about 20% tin, etc.

[0122] In various embodiments, a stannate salt, such as sodium stannate trihydrate (Na2SnO3·3H2O), potassium stannate trihydrate (K2SnO3·3H2O), or the like, may be added to or present in an electrochemical cell. In various embodiments, a stannate salt, such as sodium stannate trihydrate (Na2SnO3·3H2O), potassium stannate trihydrate (K2SnO3·3H2O), or the like, may be added to or present in an Fe anode or electrolyte of an electrochemical cell, such as a battery, in an amount of about 0.1% to about 20% by weight. By way of example, stannates, such as sodium stannate trihydrate (Na2SnO3·3H2O), potassium stannate trihydrate (K2SnO3·3H2O), etc., may be added or present in an Fe anode or electrolyte of an electrochemical cell, such as a battery, in an amount of about 0.1 wt.%, about 0.1 wt.% to about 15 wt.%, about 15 wt.%, about 15 wt.% to about 20 wt.%, about 20 wt.%, etc.

[0123] In one experiment, 0.1 M sodium stannate (Na2SnO3·3H2O) was dissolved in a 6 M potassium hydroxide-based electrolyte to provide a source of tin for incorporation into the anode. Specifically, after dissolving the sodium stannate, the composition of the electrolyte to which sodium stannate was added was 5.95 M KOH, 0.05 M LiOH, 0.007 M Na2S, and 0.1 M Na2SnO3·3H2O, and the experiment showed that tin was incorporated, adsorbed, or coexisted in the anode. The cells showed improved total capacity, step 1 capacity, and voltaic efficiency, which results in extended round trip efficiency over the full cycle (20+ cycles). In various embodiments, when adjusting the electrolyte composition by using NaOH in addition to or instead of KOH as part of the electrolyte, molar concentrations similar to those obtained from the weight percentages above in the potassium hydroxide-based electrolyte may be used to achieve similar levels of performance. Other experiments have shown that sulfides such as Na2S do not need to be included in the electrolyte if sulfides can be included in the anode or electrochemical cell. In such experiments, sodium stannate was added after dissolving sodium stannate and the composition of the electrolyte before contact with the anode or other electrode was 5.95 M KOH, 0.05 M LiOH, and 0.04 M Na2SnO3 3H2O.

[0124] In a separate experiment, 5 wt% sodium stannate (Na2SnO3·3H2O) (representing 2.22 wt% Sn relative to the iron active material) was mixed with the iron source to the anode prior to testing. Specifically, after dissolving the sodium stannate, the composition of the electrolyte with added sodium stannate was 5.95M KOH, 0.05M LiOH, 0.01M Na2S, 5 wt% Na2SnO3·3H2O, and the experiment showed that in addition to increasing the total capacity and step 1 capacity, tin was incorporated into the anode.

[0125] In some embodiments, tin oxide (SnO2) may be dissolved in the electrolyte at a concentration of 0.01% to 20% by weight. In some aspects, the SnO2 source may be cassiterite ore. In some aspects, the SnO2 source may be smelted and / or purified SnO2 as opposed to mined cassiterite ore.

[0126] In some embodiments, cassiterite (Pb3Sn4FeSb2S 14 ) may be added to the electrolyte and / or the electrodes.

[0127] In some embodiments, copper iron tin sulfide (Cu2FeSnS4) may be added to the electrolyte and / or electrodes.

[0128] In some embodiments, tin metal may be added to the electrolyte and / or the electrodes.

[0129] In some embodiments, tin sulfide (SnS or SnS2) may be added to the electrolyte and / or electrodes.

[0130] In certain embodiments in which the tin or tin-containing compound is a solid, the specific surface area of ​​the solid (measured by Brunauer-Emmett-Teller gas adsorption, m 2 / g) can be optimized to provide a particular level of reactivity such that there is a constant flux of tin entering the liquid phase, or to maintain the tin concentration in the liquid electrolyte phase above a particular critical concentration.

[0131] In some embodiments, electrolytes for use with iron negative electrodes may contain tin-containing ions. The particular type of ion or tin-containing ions may vary based on the pH and potential of the solution. In alkaline electrolytes, tin ions are present in the form of SnO3 2- or Sn(OH)6 2- In some embodiments, the concentration of the tin-containing ions may be selected so that the tin dissolved in the solution is between 0.01 and 20 percent by weight of the iron active material of the negative electrode.

[0132] In various embodiments, the tin and / or tin-containing compounds may be included in the electrochemical cell in any suitable manner that results in the incorporation of tin into the iron anode. By way of example, the tin and / or tin-containing compounds may be provided to the electrochemical cell in any of the various manners discussed with respect to the addition of additives to the electrochemical cell.

[0133] In some embodiments, tin and / or tin-containing compounds may be deposited on the anode and / or cathode of the electrochemical cell, for example, by electroless deposition. In some embodiments, a tin reservoir may be provided in the electrochemical cell. The tin reservoir allows more tin to be added to the electrochemical cell than the solubility limit would allow. In some embodiments, the tin reservoir may be connected to a source of oxidizing potential to promote dissolution of the tin through the formation of soluble tin-containing ionic species. In some embodiments, the tin and / or tin-containing compounds may be supersaturated in the electrolyte. In some embodiments, the tin and / or tin-containing compounds may be placed in the electrolyte as a foil, rod, or other form factor and may dissolve in the electrolyte over time. In certain embodiments, the electrode held at a more positive (more anodic) potential may be tin-coated first. As a non-limiting example, in an iron-air battery, the positive air electrode is first coated with tin, and the tin species are electrically driven away from the positive electrode into solution. In certain embodiments, the air electrode may be an oxygen evolution reaction (OER) electrode. The tin (or tin-bearing) coating may be applied by a process known to those skilled in the art, such as, for example, "hot dip." When the tin-coated electrode is first polarized to an anodic potential while in contact with an alkaline electrolyte, the tin species electrochemically dissolves into solution and produces a stannate in the electrolyte. In various embodiments, the tin coating may be applied to any portion of the oxidized surface. In some embodiments, there is a block or other shaped structure of tin attached to the OER electrode and / or the oxygen reduction reaction (ORR) electrode that corrodes away, thereby adding tin to the electrolyte.

[0134] In various embodiments, tin and / or tin-containing compounds may be added to the electrochemical cell as the electrochemical cell is operated. For example, a tin and / or tin-containing compound insert may be placed in the electrochemical cell, additional tin and / or tin-containing compounds may be pumped and / or otherwise added to the electrochemical cell, and / or tin and / or tin-containing compounds may be added in other ways such that a selected molar amount and / or weight percentage of tin and / or tin-containing compounds is maintained in the electrolyte and / or electrodes.

[0135] In various embodiments, antimony (Sb) and / or antimony-containing compounds may be included (e.g., added, present, etc.) in the electrochemical cell, for example, in the electrolyte, as part of an electrode, as a reservoir in the electrochemical cell, etc. Antimony and / or antimony-containing compounds may be substituted for the tin and / or tin-containing compounds described above and may operate in a similar manner to coat an iron anode and help improve the charging / recharging of an electrochemical cell by reducing or stopping the HER reaction. Figure 3 is a Pourbaix diagram for antimony.

[0136] Various embodiments include the use of tin- and / or antimony-containing compounds as additives to electrolytes and / or electrodes in electrochemical systems, such as batteries, having iron-based anodes. In various embodiments, the addition of stannates can improve the total capacity, step 1 capacity, coulombic efficiency, voltage efficiency, and cyclability of iron-based anodes.

[0137] Various embodiments may include an electrochemical cell including an iron anode having an electrolyte with a high hydroxide concentration, for example, an electrolyte with a hydroxide concentration of about 6M or more (e.g., about 6M, 6M, about 6M or more, about 6M to about 7M, 6M to 7M, about 7M or more, about 7M to about 11M, about 7M to about 10M, about 7.5M to about 9.5M, greater than 7.5M but less than 9.5M, etc.). An electrolyte with a high hydroxide concentration may provide better step 1 reaction, i.e., Fe+2OH - ←→Fe(OH)2+2e -Various embodiments may include a highly concentrated alkaline electrolyte having a high hydroxide concentration, e.g., about 6M or more (e.g., about 6M, 6M, about 6M or more, about 6M to about 7M, 6M to 7M, about 7M or more, about 7M to about 11M, about 7M to about 10M, about 7.5M to about 9.5M, greater than 7.5M but less than 9.5M, etc.) for an iron electrode electrochemical cell, such as an iron anode battery. In various embodiments, the hydroxide in the electrolyte may be KOH, NaOH, LiOH, RbOH, CsOH, FrOH, Be(OH), Ca(OH), Mg(OH), Sr(OH), Ra(OH), 2、 The mixture may include any one or more of Ba(OH)2 and mixtures thereof. In various embodiments, KOH, NaOH, and LiOH are combined in a ratio of [KOH]>[NaOH]>[LiOH]. Various embodiments may include approximately 4M KOH, 2M NaOH, 0.05M LiOH, or other combinations thereof. In various embodiments, KOH, NaOH, and LiOH are combined in a ratio of [NaOH]>[KOH]>[LiOH]. Various embodiments may include approximately 4M NaOH, 2M KOH, 0.05M LiOH, or other combinations thereof.

[0138] Traditionally, iron-based batteries have not been operated for more than about 16 hours, with 4-12 hours of duration being typical. In other words, traditionally, iron-based batteries have been operated in discharge mode for more than about 16 hours, with 4-12 hours of discharge mode time being typical. Thus, traditionally, iron-based batteries have been tested at relatively high discharge rates, e.g., 1-8 hours to discharge the full capacity of a traditional iron-based battery. These relatively short traditional discharge times and the relatively high discharge rates of traditional testing have led to the effects of longer discharge times, such as >24 hours, 24-30 hours, >30 hours, 30-100 hours, >100 hours, 100-150 hours, >150 hours, on unexplored iron-based electrochemical cells. In particular, the effects of high hydroxide electrolytes, such as hydroxide electrolytes having about 6M or more hydroxide in the electrolyte, have not been previously investigated for iron-based electrochemical cells having long discharge times, such as >24 hours, 24 hours to 30 hours, >30 hours, 30 hours to 100 hours, >100 hours, 100 hours to 150 hours, and >150 hours.

[0139] The inventors have found through experimentation that hydroxide concentrations below about 6M for a particular anode material result in lower performance than higher hydroxide concentrations, e.g., about 6M, 6M, or greater, for that particular anode material. The inventors have particularly found that hydroxide content has a much stronger impact on performance than would be expected from prior literature when using lower purity (and therefore lower cost) materials and cycling at lower rates. Thus, in the context of long-term, ultra-low-cost, grid-scale energy storage, high hydroxide content has unique and unexpected benefits to battery performance, useful not only for increasing the storage of charge stored in the cell (i.e., the capacity of the battery material), but also usefully reducing the overvoltage of the battery (i.e., increasing the voltage). High hydroxide concentrations, e.g., about 6M or greater, are not intuitively driven by the fact that they result in electrolytes with lower conductivity, higher viscosity, and higher cost than low hydroxide electrolytes. The inventors have found that for durations greater than 24-30 hours, the hydroxide content has a very strong effect on battery capacity, with the preferred hydroxide concentration being greater than 7M in the electrolyte. Hydroxide concentrations up to about 11M have been tested, with improved performance even at these very high concentrations. The upper limit on hydroxide concentration is the solubility limit, which is displayed in FIG. 5 for KOH. The solubility limit is temperature dependent, and electrochemical cells such as batteries may be insulated and / or otherwise heated to achieve higher operating temperatures and achieve higher hydroxide solubility. In some embodiments, exceeding the solubility limit to obtain an excess supply of solid hydroxide may be beneficial to maintain as high a concentration of hydroxide as possible when side reactions in the electrolyte result in a net loss of hydroxide. In various embodiments, hydroxide replenishment may also be achieved by dosing hydroxide salts in the electrolyte throughout the life of the battery.

[0140] Various embodiments may include an electrochemical cell, such as a battery, having an iron negative electrode (also referred to as an iron anode) and an electrolyte having a total hydroxide concentration of greater than 7M. In some embodiments, the electrolyte may have a total hydroxide concentration of greater than 7M, equal to or greater than the solubility limit of hydroxide in the electrolyte. In some embodiments, the total hydroxide concentration is greater than 7M, including greater than 6M KOH+NaOH and greater than 0.05M LiOH. In some embodiments, the electrolyte may have a total hydroxide concentration of 11M or less therein. In some embodiments, the electrolyte may have a total hydroxide concentration of 11M or less, including 1M or less LiOH and 10M or less KOH therein. In some embodiments, if the electrolyte is KOH-based, the total hydroxide concentration may be greater than 7M and less than 10M. In some embodiments, if the electrolyte is KOH-based, the total hydroxide concentration may be greater than 7.5M and less than 9.5M.

[0141] In some embodiments, sulfide may be included as an additional additive in the electrolyte, typically as sodium sulfide, at a sulfide concentration of 0.001M to 0.5M. Other salts, such as potassium sulfide, may be used to add sulfide to the electrolyte. In some embodiments, no additional sulfide may be added to the electrolyte. For example, the electrolyte may have no sulfide therein. In some embodiments, sulfide may be present in other aspects of the electrochemical cell, such as in the form of an additive to the anode. As an example, sulfide or a sulfide-containing compound may be an additive to the anode when the electrolyte does not include sulfide. In various embodiments, other electrolyte additives known in the art to improve performance or iron electrodes may also be used in the electrolyte. In various embodiments, the solvent for the electrolyte is generally water, and may preferably be high purity water, e.g., deionized water.

[0142] 4 is a graph showing experimental results of different DRI types using different hydroxide concentrations, according to various embodiments. Cycling with the anode half-cell at different hydroxide electrolyte concentrations confirmed that 6M hydroxide in the electrolyte produced poorer performance than higher hydroxide concentrations (e.g., 7M hydroxide or higher) for several different low-purity iron materials (labeled as "DRI types" in FIG. 4, specifically four different low-purity iron materials labeled "1," "2," "3," and "4" in FIG. 4). More specifically, increasing electrolyte hydroxide content increases the iron oxidation reaction that follows, namely, step 1 reaction Fe+2OH - ←→Fe(OH)2+2e - It has been found that increasing the capacity achieved by the Step 1 reaction not only increases the total energy stored in the battery, but also increases the voltage efficiency of the cell, resulting in an increase in the overall round trip efficiency.

[0143] Various embodiments include the use of electrolytes with high hydroxide concentrations, such as hydroxide concentrations of 7 Molar (M) or greater, in electrochemical systems such as batteries. In various embodiments, electrolytes with high hydroxide concentrations, such as hydroxide concentrations of 7 M or greater, may increase the amount of charge stored in the cell (i.e., the capacity of the battery materials), improve coulombic efficiency (i.e., increase the proportion of electrons that are stored in the intended charge product rather than wasted in side reactions), and / or reduce the overpotential of the battery (i.e., increase the voltage).

[0144] In various embodiments, alkyl polyglucosides may be used as co-additives with metal HER inhibitors.

[0145] Various additives are used in batteries to optimize performance across a range of metrics, especially accessible capacity and coulombic efficiency. Some classes of additives that are good HER inhibitors can also be electrochemically active at the same or similar potential window as the target electrode (e.g., metallic HER inhibitors or conductive additives). These additives can reversibly deposit on the electrode, causing the electrode microstructure to change over time, forming dendrites or passivation films that can short out the cell or cause other failures.

[0146] In various embodiments, organic additives, such as a class of compounds known as alkyl polyglucosides (APGs), can be used to control the chemical or electrochemical deposition of metal ions to prevent the formation of dendrites or to develop and maintain a specific structure on the surface of the electrode. APGs are organic surfactants derived from glucose and aliphatic alcohols. The alcohol functional groups of APGs can improve solubility in aqueous solutions. It is believed that APG molecules adsorb to the iron surface, limiting the rate of deposition of additives on the surface and promoting the formation of a uniform and controlled deposit on the surface. In some embodiments, organic additives, including but not limited to APGs, may be included in the electrolyte as additional additives. In some embodiments, organic additives may be included in the electrolyte after the first charge (i.e., "dosing" the cell). In some embodiments, organic additives may include other surfactant chemicals, including but not limited to linear alkyl benzene sulfonates, lignin sulfonates, aliphatic alcohol ethoxylates, and / or alkyl phenol ethoxylates.

[0147] Various embodiments may include the incorporation of tin into the current collector.

[0148] To improve the efficiency of iron oxide reduction, additives that slow hydrogen evolution or reduce HER activity on the iron electrode may be used. These additives may be incorporated in various ways and with different form factors to maximize their interaction and effect with the electrode of interest. In various embodiments, additives that reduce HER activity may be incorporated into the current collector.

[0149] Various embodiments may include incorporating tin or other metals / species into the current collector. In various embodiments, the metals / species incorporated into the current collector may be HER-inhibiting metals / species or metals / species that reduce HER activity. In some embodiments, the metals / species, including but not limited to tin, are plated onto the current collector. In some embodiments, the metals / species, including but not limited to tin, are plated onto the current collector in a layer of sufficient thickness to provide an amount of tin or other HER inhibitors of 0.1 M or less when dissolved in the electrolyte. In some embodiments, the metals / species, including but not limited to tin, are coated by hot tin dip on one or both sides of the current collector that contacts the anode. In some embodiments, the metals / species, including but not limited to tin, are electroplated onto the current collector. In some embodiments, the current collector is stainless steel, carbon steel, or nickel. In some embodiments, a mixture of metals / species, including but not limited to tin and lead, is used.

[0150] Various embodiments may include the incorporation of tin into the sponge iron.

[0151] Tin can be a performance enhancing additive in electrochemical energy storage systems using iron anodes. More homogeneous incorporation of tin-containing additives is expected to improve the performance of iron electrodes. Low-cost iron sponge-based materials cannot be produced with tin incorporation, and heterogeneous incorporation may limit the performance of these materials. Similarly, sulfide additives have been shown to improve the performance of iron anodes, including Na2S, FeS, SnS, SnS2, MnS, and ZnS. Homogeneous incorporation of any solid-state additive into sponge iron precursors can be difficult, especially in a cost-effective manner.

[0152] In various embodiments, the desired additives may be incorporated into the powder mixture used to make sponge iron prior to reduction of the sponge iron. In various embodiments, the additives may be incorporated in such a way that the final product arrives in the desired state (rather than evaporating or changing state in a way that irreversibly causes loss of functionality of the additive).

[0153] In some embodiments, cassiterite ore concentrate or some other tin oxide source, e.g., SnO2, may be incorporated into the iron ore concentrate for use in making direct reduced iron (DRI), so that the tin oxide source is not vaporized during the combustion step and is then co-reduced with the iron oxide to produce a tin-containing sponge after the reduction process is completed. In some embodiments, sodium, zinc, or manganese sulfide is added to the iron oxide powder, which is reduced to form a spongy iron oxide containing sodium sulfide, zinc sulfide, or manganese sulfide. In some embodiments, multiple desired solid state additives, e.g., cassiterite (PbSn4FeSb2S 14 A material or combination of materials containing tin or other desired solid state additives are incorporated into the iron ore concentrate prior to reduction. In some embodiments, tin or other desired solid state additives are incorporated into the iron ore concentrate prior to reduction.

[0154] In various embodiments, if the solid-state additive is soluble in the electrolyte, the solid-state additive may be a pore former to increase the porosity of the iron electrode. In one example, a tin-based additive may be provided that dissolves in the electrolyte for the iron negative electrode. In such cases, the additive serves multiple design roles at once.

[0155] Various embodiments may include a hydrogen oxidation catalyst and / or a hydrogen getter as an additive to the anode of the electrochemical cell.

[0156] During operation of an electrochemical energy storage (ESS), the electrodes of the ESS participate in electrochemical reduction and oxidation reactions. Hydrogen is a possible product of the reduction reaction of the ESS from the protic electrolyte or the aqueous electrolyte produced at the negative electrode (negode). In some embodiments, hydrogen generation by electrolysis of the electrolyte may be desirable (e.g., in flow batteries where the anolyte contains soluble hydrogenation products). However, in other embodiments, such as metal-air batteries, hydrogen generation (e.g., during charging of the metal negode) may have undesirable effects on the operation and health of the ESS.

[0157] The first undesirable consequence of hydrogen generation in a metal negode during charging can be the formation of hydrogen bubbles. The formation of bubbles in the electrolyte can adversely affect the performance of the ESS by limiting the contact between the electrolyte and the negode surface. The limited contact between the electrolyte and the negode surface can have knock-on adverse effects, such as limiting the rate performance of the ESS and causing inhomogeneity in the current distribution (hot spots) on the negode surface. The generation of hydrogen gas can result in a pressure increase, for example in an ESS that is composed of a closed or semi-closed compartment, the compartment further contains a reduced metal negode (iron negode). Furthermore, the pressure increase can adversely affect the safety and health of the ESS by causing a leak in the compartment or by being a fuel source for uncontrolled combustion or reduction side reactions in the ESS.

[0158] A second undesirable consequence of hydrogen evolution in metal negode during charging is that charge is converted into parasitic by-products, which, for example, reduce the efficiency of the ESS and are useless for productive charging and discharging.

[0159] Various embodiments may mitigate adverse effects resulting from hydrogen generation. In some embodiments, adverse effects resulting from hydrogen generation may be mitigated by including a molecular hydrogen getter to trap hydrogen in a soluble or semi-soluble form. The getter may be a degasser, absorber, or scavenger. Examples of reversible getters include zirconium, magnesium-nickel alloys, AB5 lanthanide-nickel alloys, graphitic materials (graphite, graphene, low-dimensional carbon materials), phenylpropargyl ether, and dimerized phenylpropargyl ether. Additionally, irreversible getters may be used in various embodiments in combination with or in place of reversible getters. In various embodiments, the getter may be a surface in contact with the electrolyte. In various embodiments, the getter may be a filler mixed into the anode composite. In various embodiments, the getter may be a molecular component of the electrolyte. The purpose of the getter may be to sequester H2 - suppress bubbles (mechanical / surface blocking effect), to sequester H2 to prevent it from being consumed in the combustion reaction or as fuel in side reactions, to capture hydrogen so that it is consumed when adding HOR up to the reversible capacity of the ESS.

[0160] In some embodiments, the adverse effects due to hydrogen evolution may be mitigated by including a HOR catalyst, the purpose of which is to enable consumption of hydrogen in productive oxidation (HOR) during discharge, increase the reversible capacity of the ESS, and improve the coulombic efficiency (and thus the round-trip energy efficiency of the ESS system).

[0161] Various embodiments may include lignosulfonates used as electrolyte additives and / or anion selective membranes.

[0162] Irreversible loss of sulfides from iron anodes during cycling or calendar aging in electrochemical cells is one of the main causes of the loss of accessible capacity of iron anodes over time. Sulfides may be added to the anode or electrolyte of iron-based batteries to activate the anode material. Reduction of iron during charging can release some amount of sulfide. After being released from the iron surface, sulfide migrates to the positive electrode and is rapidly and irreversibly oxidized. Even when no potential is applied, oxidation can still occur in the presence of an electrode with a sufficiently positive open circuit potential or an oxidizing agent (such as oxygen). This oxidation leads to the accumulation of oxidized sulfur species such as sulfate in the electrolyte and on the positive electrode. In certain electrolytes, sulfate precipitates as alkali sulfates and occludes the active area of ​​the electrode by clogging pores by chemisorption or physisorption, or by physically blocking the diffusion pathway to the electrode surface by accumulation of precipitates in the electrolyte.

[0163] In various embodiments, additives can be added to the anode or electrolyte to reduce sulfide migration to the positive electrode or to consume sulfides or sulfates released from the anode. In various embodiments, anion selective membranes or separators can be introduced between the negative and positive electrodes to prevent (or further impede) the migration of certain ions.

[0164] In various embodiments, lignin and its derivatives, such as lignosulfonates, can be used as additives in the electrolyte, as part of the membrane, and / or as sulfide sinks in batteries containing iron anodes. In caustic solutions, lignin reacts with sulfides and their oxidation byproducts to produce lignosulfonates, which can react with sulfides before they reach the positive electrode, thereby preventing the migration of sulfides to the positive electrode. The resulting lignosulfonates then chelate impurities in the electrolyte, preventing potentially harmful chemicals or ions from interacting with either electrode. In various embodiments, lignosulfonates can be incorporated into the system in the electrical connection to the anode, in a permeable container adjacent to the anode, and / or in the electrolyte.

[0165] In some embodiments, lignin, lignosulfonate, or a mixture of the two may be added directly to the electrolyte solution prior to, immediately prior to, or during cycling in the range of 0.1% to 10% by volume (e.g., 5.95 M KOH, 0.05 M LiOH, 0.01 M Na2S). In some embodiments, a lignosulfonate type additive, including but not limited to sodium lignosulfonate, may be included in the electrolyte as an additional additive in a concentration of 0.1% to 10% by volume. In some embodiments, the lignosulfonate type may be included in a concentration of 0.1% to 1% by volume. In some embodiments, the lignosulfonate type additive may be included in a concentration of 1% to 10% by volume. In some embodiments, the lignosulfonate type additive may be included in the electrolyte after a period of formation cycling (i.e., "dosing" the cell). In some embodiments, a lignosulfonate type additive may be included in the electrolyte after sulfides in solution are determined to be below a certain threshold (e.g., <1.0E-3M or <1.0E-6M). In some embodiments, the lignosulfonate type additive may include other chemistries, including but not limited to other functionalized sulfonic acids.

[0166] In some embodiments, lignin, lignosulfonate, or a mixture of the two may be added directly to the anode. In some embodiments, a lignosulfonate type additive, including but not limited to sodium lignosulfonate, may be included directly in the anode as an additive. In some embodiments, a lignosulfonate type may be included directly in the anode as an additive. In some embodiments, a lignosulfonate type additive may be included in the anode as an additive. In some embodiments, a lignosulfonate type additive may be included in the anode before it is assembled into an electrode. In some embodiments, a lignosulfonate type additive may be incorporated on the outside of the anode after formation.

[0167] In various embodiments, the lignin, lignosulfonate, or a mixture of the two may be coated onto a membrane that is placed in an electrochemical cell. FIG. 7 shows an aspect of an electrochemical cell including a lignosulfonate membrane, according to various embodiments. In some embodiments, the lignin, lignosulfonate, or a mixture of the two may be coated onto a membrane (e.g., cellulose, Celgard, etc.), which is then placed between an Fe negative electrode and a Ni positive electrode. The cell may then be filled with a sulfide-containing electrolyte solution (e.g., 5.95 M KOH, 0.05 M LiOH, 0.01 M Na2S) and cycled normally. In some embodiments, the lignin, lignosulfonate, or a mixture of the two may be coated onto a membrane (e.g., cellulose, Celgard, etc.), which is then placed between an Fe negative electrode and a Ni positive electrode that contains a sulfide source. The cell may then be filled with a sulfide-free electrolyte solution (5.95 M KOH, 0.05 M LiOH, etc.) and cycled normally. In some embodiments, lignin, lignosulfonate, or a mixture of the two is coated onto a membrane (e.g., cellulose, Celgard, etc.), which is then placed between an Fe anode containing a sulfide source and a Ni cathode. The cell may then be filled with a sulfide-containing electrolyte solution (e.g., 5.95 M KOH, 0.05 M LiOH, 0.01 M Na2S) and cycled normally.

[0168] Various embodiments may provide devices and / or methods for use in bulk energy storage systems, such as long-term energy storage (LODES) systems, short-term energy storage (SDES) systems, etc. As an example, various embodiments may provide batteries for bulk energy storage systems, such as batteries for LODES systems. Renewable energy sources are becoming increasingly prevalent and cost-effective. However, many renewable energy sources face intermittency issues that hinder the adoption of renewable energy sources. The impact of renewable energy sources being prone to intermittency can be mitigated by pairing them with bulk energy storage systems, such as LODES systems, SDES systems, etc. To support the adoption of combined generation, transmission, and storage systems (e.g., renewable generation sources paired with bulk energy storage systems, and power plants with transmission facilities in either the power plant and / or the bulk energy storage system), devices and methods are needed to support the design and operation of such combined generation, transmission, and storage systems, such as the various embodiment devices and methods described herein.

[0169] A combined generation, transmission, and storage system may be a power plant that includes one or more generation sources (e.g., one or more renewable generation sources, one or more non-renewable generation sources, a combination of renewable and non-renewable generation sources, etc.), one or more transmission facilities, and one or more bulk energy storage systems. The transmission facilities in either the power plant and / or the bulk energy storage systems may be co-optimized with the generation and storage systems or may impose constraints on the design and operation of the generation and storage systems. The combined generation, transmission, and storage system may be configured to meet various output targets under various design and operational constraints.

[0170] 8-16 illustrate various exemplary systems in which one or more aspects of various embodiments can be used as part of a bulk energy storage system, such as a LODES system, an SDES system, etc. For example, various embodiments described herein with reference to FIGS. 1-16 can be used as batteries for a bulk energy storage system, such as a LODES system, an SDES system, etc., and / or various electrodes described herein can be used as components of a bulk energy storage system. As used herein, the term "LODES system" refers to a bulk energy storage system configured to have a rated duration (energy / power ratio) of 24 hours (h) or longer, such as a duration of 24 hours, a duration of 24 hours to 50 hours, a duration of more than 50 hours, a duration of 24 hours to 150 hours, a duration of more than 150 hours, a duration of 24 hours to 200 hours, a duration of more than 200 hours, a duration of 24 hours to 500 hours, a duration of more than 500 hours, etc.

[0171] FIG. 8 illustrates an exemplary system in which one or more aspects of the various embodiments may be used as part of a bulk energy storage system. As a specific example, a bulk energy storage system incorporating one or more aspects of the various embodiments may be a LODES system 2404. As an example, the LODES system 2404 may include various embodiment batteries described herein, various electrodes described herein, and the like. The LODES system 2404 may be electrically connected to a wind farm 2402 and one or more transmission facilities 2406. The wind farm 2402 may be electrically connected to the transmission facility 2406. The transmission facility 2406 may be electrically connected to a power grid 2408. The wind farm 2402 may generate power, and the wind farm 2402 may output the generated power to the LODES system 2404 and / or the transmission facility 2406. The LODES system 2404 may store the power received from the wind farm 2402 and / or the transmission facility 2406. The LODES system 2404 can output the stored power to a transmission facility 2406. The transmission facility 2406 can output power received from one or both of the wind farm 2402 and the LODES system 2404 to a grid 2408 and / or can receive power from the grid 2408 and output the power to the LODES system 2404. The wind farm 2402, the LODES system 2404, and the transmission facility 2406 can together comprise a power plant 2400, which may be a combined power, transmission, and storage system. Power generated by the wind farm 2402 may be fed directly to the grid 2408 via the transmission facility 2406 or may first be stored in the LODES system 2404. In certain cases, the power supplied to the power grid 2408 may be provided entirely from the wind farm 2402, entirely from the LODES system 2404, or from a combination of the wind farm 2402 and the LODES system 2404.The distribution of power from the combined wind farm 2402 and LODES system 2404 power plant 2400 may be controlled according to a predetermined long-term (multi-day or even multi-year) schedule, or according to a day-ahead (24-hour notice) market, or according to an hour-ahead market, or in response to real-time pricing signals.

[0172] As one example of the operation of the power plant 2400, the LODES system 2404 can be used to reshape and "stabilize" the power produced by the wind farm 2402. In one such example, the wind farm 2402 may have a peak power output (capacity) of 260 megawatts (MW) and a capacity factor (CF) of 41%. The LODES system 2404 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, the wind farm 2402 may have a peak power output (capacity) of 300 MW and a capacity factor (CF) of 41%. The LODES system 2404 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, the wind farm 2402 may have a peak power output (capacity) of 176 MW and a capacity factor (CF) of 53%. The LODES system 2404 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 another such example, the wind farm 2402 may have a peak power output (capacity) of 277 MW and a capacity factor (CF) of 41%. The LODES system 2404 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 another such example, the wind farm 2402 may have a peak power output (capacity) of 315 MW and a capacity factor (CF) of 41%. The LODES system 2404 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.

[0173] FIG. 9 illustrates an exemplary system in which one or more aspects of the various embodiments may be used as part of a bulk energy storage system. As a specific example, a bulk energy storage system incorporating one or more aspects of the various embodiments may be a LODES system 2404. As an example, the LODES system 2404 may include various embodiment batteries described herein, various electrodes described herein, and the like. The system of FIG. 9 may be similar to the system of FIG. 8, except that a photovoltaic (PV) station 2502 may be used instead of the wind power station 2402. The LODES system 2404 may be electrically connected to the PV station 2502 and one or more transmission facilities 2406. The PV station 2502 may be electrically connected to the transmission facility 2406. The transmission facility 2406 may be electrically connected to the power grid 2408. The PV station 2502 may generate power, and the PV station 2502 may output the generated power to the LODES system 2404 and / or the transmission facility 2406. The LODES system 2404 can store power received from the PV station 2502 and / or the transmission facility 2406. The LODES system 2404 can output the stored power to the transmission facility 2406. The transmission facility 2406 can output power received from one or both of the PV station 2502 and the LODES system 2404 to the grid 2408 and / or can receive power from the grid 2408 and output the power to the LODES system 2404. The PV station 2502, the LODES system 2404, and the transmission facility 2406 together can comprise a power plant 2500, which may be a combined power, transmission, and storage system. Power generated by the PV station 2502 may be fed directly to the grid 2408 via the transmission facility 2406 or may first be stored in the LODES system 2404. In certain cases, the power supplied to the power grid 2408 may be provided entirely from the PV stations 2502, entirely from the LODES systems 2404, or from a combination of the PV stations 2502 and the LODES systems 2404.The distribution of power from the combined PV base 2502 and LODES system 2404 power plant 2500 may be controlled according to a predetermined long-term (multi-day or even multi-year) schedule, or according to a day-ahead (24-hour notice) market, or according to an hour-ahead market, or in response to real-time pricing signals.

[0174] As one example of the operation of the power plant 2500, the LODES system 2404 can be used to reshape and "balance" the power produced by the PV station 2502. In one such example, the PV station 2502 may have a peak power output (capacity) of 490 MW and a capacity factor (CF) of 24%. The LODES system 2404 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, the PV station 2502 may have a peak power output (capacity) of 680 MW and a capacity factor (CF) of 24%. The LODES system 2404 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, the PV station 2502 may have a peak power output (capacity) of 330 MW and a capacity factor (CF) of 31%. The LODES system 2404 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, the PV station 2502 may have a peak power output (capacity) of 510 MW and a capacity factor (CF) of 24%. The LODES system 2404 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 another such example, the PV station 2502 may have a peak power output (capacity) of 630 MW and a capacity factor (CF) of 24%. The LODES system 2404 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.

[0175] FIG. 10 illustrates an exemplary system in which one or more aspects of the various embodiments can be used as part of a bulk energy storage system. As a specific example, the bulk energy storage system incorporating one or more aspects of the various embodiments may be a LODES system 2404. As an example, the LODES system 2404 may include various embodiment batteries described herein, various electrodes described herein, and the like. The system of FIG. 10 may be similar to the systems of FIG. 8 and FIG. 9, except that the wind farm 2402 and the photovoltaic (PV) farm 2502 may both be power generating devices operating together in a power plant 2600. The PV farm 2502, the wind farm 2402, the LODES system 2404, and the transmission facility 2406 together may comprise a power plant 2600, which may be a combined generation, transmission, and storage system. Electricity generated by the PV sites 2502 and / or wind farms 2402 may be fed directly to the grid 2408 via the transmission facility 2406 or may first be stored in the LODES system 2404. In certain cases, the electricity provided to the grid 2408 may be fed entirely from the PV sites 2502, entirely from the wind farms 2402, entirely from the LODES system 2404, or from a combination of the PV sites 2502, the wind farms 2402, and the LODES system 2404. The delivery of electricity from the combined wind farms 2402, the PV sites 2502, and the LODES system 2404 power plant 2600 may be controlled according to a predetermined long-term (multi-day or even multi-year) schedule, or according to a day-ahead (24-hour advance notice) market, or according to an hour-ahead market, or in response to real-time pricing signals.

[0176] As one example of the operation of the power plant 2600, the LODES system 2404 may be used to reshape and "stabilize" the power produced by the wind farm 2402 and the PV farm 2502. In one such example, the wind farm 2402 may have a peak power output (capacity) of 126 MW and a capacity factor (CF) of 41%, and the PV farm 2502 may have a peak power output (capacity) of 126 MW and a capacity factor (CF) of 24%. The LODES system 2404 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, the wind farm 2402 may have a peak power output (capacity) of 170 MW and a capacity factor (CF) of 41%, and the PV farm 2502 may have a peak power output (capacity) of 110 MW and a capacity factor (CF) of 24%. The LODES system 2404 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, the wind farm 2402 may have a peak power output (capacity) of 105 MW and a capacity factor (CF) of 51%, and the PV farm 2502 may have a peak power output (capacity) of 70 MW and a capacity factor (CF) of 31%. The LODES system 2404 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, the wind farm 2402 may have a peak power output (capacity) of 135 MW and a capacity factor (CF) of 41%, and the PV farm 2502 may have a peak power output (capacity) of 90 MW and a capacity factor (CF) of 24%. The LODES system 2404 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, the wind farm 2402 may have a peak power output (capacity) of 144 MW and a capacity factor (CF) of 41%, and the PV farm 2502 may have a peak power output (capacity) of 96 MW and a capacity factor (CF) of 24%.The LODES system 2404 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.

[0177] FIG. 11 illustrates an exemplary system in which one or more aspects of the various embodiments can be used as part of a bulk energy storage system. As a specific example, the bulk energy storage system incorporating one or more aspects of the various embodiments may be a LODES system 2404. As an example, the LODES system 2404 may include various embodiment batteries described herein, various electrodes described herein, etc. The LODES system 2404 may be electrically connected to one or more transmission facilities 2406. In this manner, the LODES system 2404 may operate in a "standalone" manner to arbitrate energy near market prices and / or avoid transmission constraints. The LODES system 2404 may be electrically connected to one or more transmission facilities 2406. The transmission facilities 2406 may be electrically connected to a distribution grid 2408. The LODES system 2404 may store power received from the transmission facilities 2406. The LODES system 2404 may output the stored power to the transmission facilities 2406. The power transmission facility 2406 may output power received from the LODES system 2404 to the power distribution grid 2408 and / or may receive power from the power distribution grid 2408 and output the power to the LODES system 2404.

[0178] The LODES system 2404 and the transmission facility 2406 together can constitute a power generation plant 900. As an example, the power generation plant 900 may be located downstream of the transmission constraints, close to the power consumption. In such an exemplary downstream power generation plant 2700, the LODES system 2404 may have a duration of 24 to 500 hours and may perform full discharges once or multiple times per year to support peak power consumption at times when the transmission capacity is not sufficient to serve customers. In addition, in such an exemplary downstream power generation plant 2700, the LODES system 2404 may perform several shallow discharges (daily or more frequently) to arbitrage the difference between nighttime and daytime electricity prices and reduce the overall cost of electricity service to customers. As a further example, the power generation plant 2700 may be located upstream of the transmission constraints, close to the power generation. In such an exemplary upstream power plant 2700, the LODES system 2404 may have a duration of 24 hours to 500 hours and may fully charge once or multiple times per year to absorb excess generation at times when transmission capacity is insufficient to distribute electricity to customers. In addition, in such an exemplary upstream power plant 2700, the LODES system 2404 may shallowly charge and discharge several times (daily or more frequently) to arbitrage the difference between nighttime and daytime electricity prices and maximize the value of the power generation facility's output.

[0179] FIG. 12 illustrates an exemplary system in which one or more aspects of the various embodiments may be used as part of a bulk energy storage system. As a specific example, a bulk energy storage system incorporating one or more aspects of the various embodiments may be a LODES system 2404. As an example, the LODES system 2404 may include various embodiment batteries described herein, various electrodes described herein, and the like. The LODES system 2404 may be electrically connected to commercial and industrial (C&I) customers 2802, such as data centers, factories, and the like. The LODES system 2404 may be electrically connected to one or more transmission facilities 2406. The transmission facilities 2406 may be electrically connected to a distribution grid 2408. The transmission facilities 2406 may receive power from the distribution grid 2408 and output the power to the LODES system 2404. The LODES system 2404 may store the power received from the transmission facilities 2406. The LODES system 2404 may output the stored power to the C&I customers 2802. In this manner, the LODES system 2404 can operate to reshape the power purchased from the grid 2408 to match the consumption patterns of the C&I customers 2802 .

[0180] The LODES system 2404 and the transmission facility 2406 together may comprise a power generation plant 2800. As an example, the power generation plant 2800 may be located near the electricity consumption, i.e., near the C&I customers 2802, such as between the power distribution grid 2408 and the C&I customers 2802. In such an example, the LODES system 2404 may have a duration of 24 hours to 500 hours and may purchase power from the market at a time when power is cheaper, thereby charging the LODES system 2404. The LODES system 2404 may then discharge and provide power to the C&I customers 2802 at a time when the market price is higher, thus offsetting the market purchases of the C&I customers 2802. As an alternative configuration, the power generation plant 2800 may be located not between the power distribution grid 2408 and the C&I customers 2802, but between a renewable resource, such as a PV site, a wind farm, etc., and the transmission facility 2406, which may be connected to the renewable resource. In such an alternative example, the LODES system 2404 may have a duration between 24 hours and 500 hours, and the LODES system 2404 may be charged at times when renewable output may be available. The LODES system 2404 may then discharge to cover a portion or all of the C&I customer 2802 power needs and provide the C&I customer 2802 with renewable generated electricity.

[0181] FIG. 13 illustrates an exemplary system in which one or more aspects of the various embodiments may be used as part of a bulk energy storage system. As a specific example, a bulk energy storage system incorporating one or more aspects of the various embodiments may be a LODES system 2404. As an example, the LODES system 2404 may include various embodiment batteries described herein, various electrodes described herein, and the like. The LODES system 2404 may be electrically connected to a wind farm 2402 and one or more transmission facilities 2406. The wind farm 2402 may be electrically connected to the transmission facility 2406. The transmission facility 2406 may be electrically connected to a C&I customer 2802. The wind farm 2402 may generate power, and the wind farm 2402 may output the generated power to the LODES system 2404 and / or the transmission facility 2406. The LODES system 2404 may store the power received from the wind farm 2402.

[0182] The LODES system 2404 can output the stored power to the transmission facility 2406. The transmission facility 2406 can output the power received from one or both of the wind farm 2402 and the LODES system 2404 to the C&I customers 2802. The wind farm 2402, the LODES system 2404, and the transmission facility 2406 can together comprise a power plant 2900, which may be a combined generation, transmission, and storage system. The power generated by the wind farm 2402 may be delivered directly to the C&I customers 2802 via the transmission facility 2406, or may first be stored in the LODES system 2404. In certain cases, the power provided to the C&I customers 2802 may be delivered entirely from the wind farm 2402, entirely from the LODES system 2404, or from a combination of the wind farm 2402 and the LODES system 2404. The LODES system 2404 may be used to reshape electricity generated by the wind farm 2402 to match the consumption patterns of the C&I customers 2802. In one such example, the LODES system 2404 may have a duration of 24 hours to 500 hours and may charge when renewable generation by the wind farm 2402 exceeds the C&I customers 2802 loads. The LODES system 2404 may then discharge when renewable generation by the wind farm 2402 falls below the C&I customers 2802 loads to provide the C&I customers 2802 with a stable renewable profile that offsets some or all of the C&I customers 2802 electricity consumption.

[0183] FIG. 14 illustrates an exemplary system in which one or more aspects of the various embodiments can be used as part of a bulk energy storage system. As a specific example, the bulk energy storage system incorporating one or more aspects of the various embodiments can be a LODES system 2404. As an example, the LODES system 2404 can include various embodiment batteries described herein, various electrodes described herein, and the like. The LODES system 2404 can be part of a power plant 3000 that integrates a large amount of renewable generation into a microgrid, for example, blending the output of renewable generation by PV site 2502 and wind power site 2402 with existing thermal generation by thermal power plant 3002 (e.g., gas plant, coal plant, diesel generator set, etc., or a combination of thermal generation methods), where the renewable generation and thermal generation are used to supply C&I customer 2802 loads when availability is high. A microgrid such as the microgrid composed of power plant 3000 and thermal power plant 3002 can provide an availability of 90% or higher. Electricity generated by the PV site 2502 and / or wind farm 2402 may be delivered directly to C&I customers 2802 or may first be stored in the LODES system 2404 .

[0184] In a particular case, the power provided to the C&I customers 2802 may be entirely from the PV sites 2502, entirely from the wind farms 2402, entirely from the LODES systems 2404, entirely from the thermal power plants 3002, or any combination of the PV sites 2502, the wind farms 2402, the LODES systems 2404, and / or the thermal power plants 3002. As an example, the LODES systems 2404 of the power plant 3000 may have a duration of 24 hours to 500 hours. As a specific example, the C&I customers 2802 load may be 100 MW peak, the LODES systems 2404 may have a power rating of 14 MW and a duration of 150 hours, the cost of natural gas may be $6 / million British thermal units (MMBTU), and the renewable occupancy may be 58%. As another specific example, the C&I customer 2802 load may be 100 MW peak, the LODES system 2404 may have a power rating of 25 MW and a duration of 150 hours, the cost of natural gas may be $8 / million British thermal units (MMBTU), and the renewable occupancy may be 65%.

[0185] FIG. 15 illustrates an exemplary system in which one or more aspects of the various embodiments can be used as part of a bulk energy storage system. As a specific example, the bulk energy storage system incorporating one or more aspects of the various embodiments may be a LODES system 2404. As an example, the LODES system 2404 may include the various embodiment batteries described herein, the various electrodes described herein, and the like. The LODES system 2404 can be used to enhance the nuclear power plant 3102 (or other inflexible power generation facilities such as thermal, biomass, and / or any other type of power plant with a ramp rate of less than 50% of rated power in one hour and a capacity factor of 80% or higher) to add flexibility to the combined output of the power plant 3100 composed of the combined LODES system 2404 and the nuclear power plant 3102. The nuclear power plant 3102 can be operated at a high capacity factor and at its highest efficiency point, and the LODES system 2404 can be charged and discharged to effectively reshape the output of the nuclear power plant 3102 to match customer electricity consumption and / or the market price of electricity. As an example, the LODES system 2404 of the power plant 3100 may have a duration of 24 hours to 500 hours. In one specific example, the nuclear power plant 3102 may have a rated power output of 1,000 MW, and the nuclear power plant 3102 may be forced to operate at minimum stable power generation or even shut down for long periods of time due to a drop in the market price of electricity. The LODES system 2404 can charge to avoid shutting down the facility when the market price drops, and then the LODES system 2404 can discharge when the market price rises, increasing the total power generation.

[0186] FIG. 16 illustrates an exemplary system in which one or more aspects of the various embodiments can be used as part of a bulk energy storage system. As a specific example, the bulk energy storage system incorporating one or more aspects of the various embodiments may be a LODES system 2404. As an example, the LODES system 2404 may include various embodiment batteries described herein, various electrodes described herein, and the like. The LODES system 2404 may operate in conjunction with an SDES system 3202. The LODES system 2404 and the SDES system 3202 together may comprise a power plant 3200. As an example, the LODES system 2404 and the SDES system 3202 may be co-optimized, such that the LODES system 2404 can provide various services including long-term backup and / or bridging over multi-day variations (e.g., multi-day variations in market prices, renewable generation, electricity consumption, and the like). The SDES system 3202 can provide various services including rapid support services (e.g., voltage control, frequency regulation, etc.) and / or bridging across diurnal variations (e.g., diurnal variations in market prices, renewable generation, electricity consumption, etc.). The SDES system 3202 may have a duration of less than 10 hours and a round trip efficiency of greater than 80%. The LODES system 2404 may have a duration of 24 hours to 500 hours and a round trip efficiency of greater than 40%. In one such example, the LODES system 2404 may have a duration of 150 hours and can support customer electricity consumption for up to one week of renewable generation shortage. The LODES system 2404 can also support customer electricity consumption during a diurnal generation shortage event to enhance the capacity of the SDES system 3202. Additionally, the SDES system 3202 can supply customers during a diurnal generation shortage event and provide quality services such as power conditioning and voltage control and frequency regulation.

[0187] Various examples of aspects of various embodiments are described in the following paragraphs.

[0188] Example 1. A battery comprising a first electrode comprising iron, an electrolyte, and a second electrode, the first electrode or the electrolyte comprising an additive. Example 2. The battery of Example 1, wherein the additive comprises an element that has low hydrogen evolution reaction (HER) activity and / or improves charging of the first electrode. Example 3. The battery of Example 1 or 2, wherein the iron comprises direct reduced iron (DRI) and / or another sponge iron powder. Example 4. The battery of any of Examples 1-3, wherein the element comprises tin and / or antimony. Example 5. The battery of any of Examples 1-3, wherein the additive comprises sodium stannate trihydrate (Na2SnO3·3H2O), metallic tin, potassium stannate trihydrate (K2SnO3·3H2O), tin oxide (SnO2), stannite (Pb3Sn4FeSb2S 14), copper iron tin sulfide (Cu2FeSnS4), lead-tin alloy (60 / 40 Sn / Pb solder, 63 / 37 Sn / Pb solder, Terne I alloy: 10-20% Sn, balance Pb), zinc-tin alloy (Terne II alloy: 10-20% Sn, balance Zn), or tin sulfide (SnS or SnS2). Example 6. The battery of any of Examples 1-5, wherein the additive is at a concentration of 0.1 mM or more in the electrolyte. Example 7. The battery of Example 6, wherein the additive is at a concentration of about 10 mM in the electrolyte. Example 8. The battery of Example 6, wherein the additive is at a concentration of about 100 mM in the electrolyte. Example 9. The battery of Example 6, wherein the additive is at a concentration of about 10 mM to about 100 mM in the electrolyte. Example 10. The battery of Example 6, wherein the additive is at a concentration of about 650 mM in the electrolyte or wherein the additive is at a concentration of about 50 mM in the electrolyte. Example 11. The battery of Example 6, wherein the additive is at a concentration of about 670 mM in the electrolyte. Example 12. The battery of Example 6, wherein the additive is at a concentration of about 750 mM in the electrolyte. Example 13. The battery of Example 6, wherein the additive is below the saturation limit in the electrolyte. Example 14. The battery of any of Examples 1-5, wherein the additive is at a concentration in the first electrode between about 0.1% by weight of the first electrode and about 20% by weight of the first electrode. Example 15. The battery of Example 14, wherein the additive is at a concentration of about 1% by weight in the first electrode. Example 16. The battery of Example 14, wherein the additive is at a concentration of about 6% by weight in the first electrode. Example 17. The battery of Example 14, wherein the additive is at a concentration of about 1% by weight to about 10% by weight in the first electrode. Example 18. The battery of any of Examples 1-17, wherein the electrolyte comprises lithium hydroxide (LiOH), potassium hydroxide (KOH) and / or sodium hydroxide (NaOH), and optionally sodium sulfide (Na2S). Example 19. The battery of any of Examples 1-18, wherein the additive is plated on the second electrode. Example 20. The battery of any of Examples 1-19, wherein the additive is disposed in a reservoir suspended in the electrolyte. Example 21. The battery of any of Examples 1-3 and 18-20, wherein the additive comprises antimony.Example 22. The battery of any one of Examples 1-21, wherein the electrolyte comprises one or more hydroxides, and the total hydroxide concentration in the electrolyte is about 6M or more. Example 23. The battery of any one of Examples 1-21, wherein the electrolyte comprises one or more hydroxides, and the total hydroxide concentration in the electrolyte is greater than 7M. Example 24. The battery of Example 23, wherein the total hydroxide concentration in the electrolyte is greater than 7M and is less than or equal to 11M. Example 25. The battery of Example 24, wherein the electrolyte comprises a combination of KOH and NaOH greater than 6M and LiOH greater than or equal to 0.05M. Example 26. The battery of Example 24, wherein the electrolyte comprises higher concentrations of KOH, NaOH, and LiOH, such that the molar concentration of KOH is greater than the molar concentration of NaOH, and the molar concentration of NaOH is greater than the molar concentration of LiOH. Example 27. The battery of Example 23, wherein the total hydroxide concentration in the electrolyte is greater than 7M and less than 10M. Example 28. The battery, for example, described in item 23, in which the total hydroxide concentration in the electrolyte is greater than 7.5M and less than 9.5M. Example 29. The battery, for example, described in example 27 or 28, in which the electrolyte contains KOH. Example 30. The battery, for example, described in example 22-29, in which the electrolyte contains at least 0.05M LiOH. Example 31. The battery, for example, described in example 22-30, in which the electrolyte contains any one or more of KOH, NaOH, LiOH, RbOH, CsOH, FrOH, Be(OH)2, Ca(OH)2, Mg(OH)2, Sr(OH)2, Ra(OH)2, Ba(OH)2, and mixtures thereof. Example 32. The battery, for example, described in example 22-31, in which the electrolyte contains sulfide. Example 33. The battery, for example, described in example 32, in which the sulfide concentration in the electrolyte is 0.001M to 0.5M. Example 34. The battery of any of Examples 21-30, wherein the electrolyte does not contain a sulfide. Example 35. The battery of any of Examples 1-34, wherein the additive is at least partially solid. Example 36. The battery of Example 35, wherein the surface area of ​​the solid is selected to provide a level of reactivity such that there is a constant flux of the additive into the liquid electrolyte phase and / or such that the additive concentration in the liquid electrolyte phase is maintained at or above a selected concentration.

[0189] Example 37. A battery comprising a first electrode comprising iron, an electrolyte, and a second electrode, wherein the electrolyte comprises one or more hydroxides.

[0190] Example 38. The battery of example 37, wherein the iron is direct reduced iron (DRI) or another sponge iron powder.

[0191] Example 39. A battery comprising a first electrode comprising direct reduced iron (DRI) or another sponge iron powder, an electrolyte comprising a hydroxide, and a second electrode, wherein the first electrode or the electrolyte further comprises an additive, the additive comprising at least one of tin, lead, or antimony.

[0192] Example 40. The battery of any of Examples 37-39, wherein the total hydroxide concentration in the electrolyte is about 6M or more. Example 41. The battery of any of Examples 37-39, wherein the total hydroxide concentration in the electrolyte is greater than 7M. The battery of Example 41, wherein the total hydroxide concentration in the electrolyte is greater than 7M and less than or equal to 11M. Example 43. The battery of Example 42, wherein the electrolyte comprises a combination of KOH and NaOH greater than 6M and LiOH greater than or equal to 0.05M. Example 44. The battery of Example 42, wherein the electrolyte comprises higher concentrations of KOH, NaOH, and LiOH such that the molar concentration of KOH is greater than the molar concentration of NaOH, and the molar concentration of NaOH is greater than the molar concentration of LiOH. Example 45. The battery of any of Examples 37-39, wherein the total hydroxide concentration in the electrolyte is greater than 7M and less than 10M. Example 46. The battery of any one of Examples 37-39, wherein the total hydroxide concentration in the electrolyte is greater than 7.5M and less than 9.5M. Example 47. The battery of Example 45 or 46, wherein the electrolyte comprises KOH. Example 48. The battery of any one of Examples 37-47, wherein the electrolyte comprises at least 0.05M LiOH. Example 49. The battery of any one of Examples 37-48, wherein the electrolyte comprises any one or more of KOH, NaOH, LiOH, RbOH, CsOH, FrOH, Be(OH)2, Ca(OH)2, Mg(OH)2, Sr(OH)2, Ra(OH)2, Ba(OH)2, and mixtures thereof. Example 50. The battery of any one of Examples 37-49, wherein the electrolyte comprises a sulfide. Example 51. The battery of Example 50, wherein the sulfide concentration in the electrolyte is 0.001M to 0.5M. Example 52. The battery according to any one of Examples 37 to 49, wherein the electrolyte does not contain sulfide.

[0193] Example 53. A bulk energy storage system comprising a stack of one or more batteries, at least one of the one or more batteries comprising a battery according to any of Examples 1 to 52. Example 54. The bulk energy storage system according to Example 53, wherein the bulk energy storage system is a long term energy storage (LODES) system. Example 55. The bulk energy storage system according to Example 54, wherein the LODES system is configured to discharge for a period of time greater than 24 hours. Example 56. The bulk energy storage system according to Example 55, wherein the LODES system is configured to discharge for a period of time greater than 30 hours. Example 57. The bulk energy storage system according to Example 55, wherein the LODES system is configured to discharge for a period of time greater than 100 hours. Example 58. The bulk energy storage system according to Example 55, wherein the LODES system is configured to discharge for a period of time greater than 150 hours.

[0194] Example 59. A method of operating a battery having an iron-based electrode, comprising adding to the battery an additive as described in any of Examples 1-36; and / or adding to the battery a hydroxide as described in any of Examples 37-52. Example 60. The method of Example 59, wherein the iron-based electrode comprises DRI or another sponge iron powder. Example 61. The method of Example 59, further comprising adding one or more organic additives to the battery's electrolyte. Example 62. The method of Example 61, wherein the one or more organic additives comprise one or more alkyl polyglucosides. Example 63. The method of any of Examples 59-62, further comprising incorporating tin into the battery's current collector. Example 64. The method of any of Examples 59-62, further comprising incorporating the selected additive into the powder mixture used to produce the sponge iron prior to reduction of the sponge iron. Example 65. The method of any of Examples 59-64, further comprising adding a HOR catalyst to the battery. Example 66. The method of any of Examples 59-65, further comprising trapping hydrogen in a soluble or semi-soluble form. Example 67. The method of any of Examples 59-66, further comprising adding an additive to the anode and / or electrolyte to reduce migration of sulfides to the positive electrode or to consume sulfides or sulfates released from the anode; and / or adding an anion selective membrane or separator to prevent migration of certain ions. Example 68. The method of Example 67, wherein the additive and / or anion selective membrane or separator comprises lignin and its derivatives, such as lignosulfonates.

[0195] Example 69. A method comprising adding one or more organic additives to an electrolyte of a battery. Example 70. The method of example 69, wherein the one or more organic additives comprise one or more alkyl polyglucosides.

[0196] Example 71. A method comprising incorporating tin into a current collector of a battery.

[0197] Example 72. A method comprising the steps of incorporating a selected additive into a powder mixture used to produce sponge iron prior to reduction of the sponge iron, and forming a battery electrode from the produced sponge iron.

[0198] Example 73. A method comprising adding an HOR catalyst to a battery.

[0199] Example 74. A method comprising trapping hydrogen in a soluble or semi-soluble form.

[0200] Example 75. A method comprising adding an additive to the anode and / or electrolyte of the battery to reduce migration of sulfides to the positive electrode or to consume sulfides or sulfates released from the anode; and / or adding an anion selective membrane or separator to the battery to prevent migration of certain ions. Example 76. The method of claim 75, wherein the additive and / or the anion selective membrane or separator comprises lignin and its derivatives, such as lignosulfonates.

[0201] Example 77. The battery of any of Examples 1-52 and / or the bulk energy storage system of any of Examples 53-58, wherein the electrolyte comprises one or more organic additives. Example 78. The battery and / or bulk energy storage system of Example 77, wherein the one or more organic additives comprise one or more alkyl polyglucosides.

[0202] Example 79. The battery of any of Examples 1-52, 77, and 78, and / or the bulk energy storage system of any of Examples 53-58, 77, and 78, further comprising a current collector having tin incorporated therein.

[0203] Example 80. The battery of any of Examples 1-52, and 77-79, and / or the bulk energy storage system of any of Examples 53-58, and 77-79, wherein the DRI or other sponge iron powder includes a selected additive incorporated into the powder mixture used to manufacture the DRI or other sponge iron powder.

[0204] Example 81. The battery of any one of Examples 1-52, and 77-80, and / or the bulk energy storage system of any one of Examples 53-58, and 77-80, further comprising a HOR catalyst and / or a hydrogen getter.

[0205] Example 82. The battery of any of Examples 1-52 and 77-81, and / or the bulk energy storage system of any of Examples 53-58 and 77-81, further comprising an additive in the first electrode and / or electrolyte to reduce migration of sulfide to the second electrode or to consume sulfide or sulfate released from the first electrode; and / or an anion selective membrane or separator to prevent migration of certain ions. Example 83. The battery and / or bulk energy storage system of Example 82, wherein the additive and / or the anion selective membrane or separator comprises lignin and its derivatives, e.g., lignosulfonates.

[0206] Example 84. A battery and / or bulk energy storage system, wherein the electrolyte comprises one or more organic additives. Example 85. The battery and / or bulk energy storage system of Example 84, wherein the one or more organic additives comprise one or more alkyl polyglucosides.

[0207] Example 86. A battery and / or bulk energy storage system, wherein a current collector has tin incorporated therein.

[0208] Example 87. A battery and / or bulk energy storage system having electrodes comprising DRI or another sponge iron powder, with selected additives incorporated into the powder mixture used to manufacture the DRI or another sponge iron powder.

[0209] Example 88. A battery and / or bulk energy storage system comprising a HOR catalyst and / or a hydrogen getter.

[0210] Example 89. A battery and / or bulk energy storage system comprising an additive in the first electrode and / or electrolyte to reduce migration of sulfides to the second electrode or to consume sulfides or sulfates released from the first electrode; and / or an anion selective membrane or separator to prevent migration of certain ions. Example 90. The battery and / or bulk energy storage system of example 89, wherein the additive and / or anion selective membrane or separator comprises lignin and its derivatives, e.g., lignosulfonates.

[0211] The above method descriptions are provided only as illustrative examples and are not intended to require or imply that the steps of the various embodiments must be performed in the order presented. As one skilled in the art would understand, the order of steps in the above embodiments may be performed in any order. Words such as "then," "then," and "next" are not necessarily intended to limit the order of steps, and such words may be used to guide the reader through the method description. Additionally, any reference to a claim element in the singular, for example, using the article "a," "an," or "the," should not be construed as limiting the element to the singular.

[0212] The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the described embodiments. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the basic principles defined herein may be applied to other embodiments without departing from the scope of the present disclosure. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the following claims and the principles and novel features disclosed herein.

Claims

1. A method for producing a catalytic converter comprising: a first electrode comprising direct reduced iron (DRI); An electrolyte; A second electrode; and A battery comprising:

14. A battery, wherein the first electrode or the electrolyte comprises an additive containing an element that has low hydrogen evolution reaction (HER) activity and / or improves charging of the first electrode.

2. 10. The battery of claim 1, wherein the element comprises tin and / or antimony.

3. The additive is sodium stannate trihydrate (Na ２ SnO ３ ・3H ２ O), metallic tin, potassium stannate trihydrate (K ２ SnO ３ ・3H ２ O), tin oxide (SnO ２ ), cylindrical stannite (Pb ３ Sn ４ FeSb ２ S １４ ), Copper iron tin sulfide (Cu ２ FeSnS ４ ), a lead-tin alloy, a zinc-tin alloy, or tin sulfide.

4. The battery of claim 1 , wherein the additive is present in the electrolyte at a concentration of 0.1 mM or greater.

5. 2. The battery of claim 1, wherein the additive is in the first electrode in an amount from 0.1% by weight of the first electrode to 20% by weight of the first electrode.

6. The electrolyte may be lithium hydroxide (LiOH), potassium hydroxide (KOH) and / or sodium hydroxide (NaOH), and optionally sodium sulfide (Na ２ S).

7. 10. The battery of claim 1, wherein the additive is plated onto the second electrode.

8. 10. The battery of claim 1, wherein the additive is disposed in a reservoir suspended in the electrolyte.

9. 10. The battery of claim 1, wherein the electrolyte comprises a sulfide.

10. The battery of claim 1 , wherein the additive is at least partially solid.

11. A method for producing a catalytic converter comprising: a first electrode comprising direct reduced iron (DRI); an electrolyte solution containing a hydroxide; A second electrode; and A battery comprising: The first electrode or the electrolyte further comprises an additive, the additive comprising at least one of tin, lead, or antimony; battery.

12. 12. The battery of claim 11, wherein the total concentration of the hydroxide in the electrolyte is 6M or greater.

13. 12. The battery of claim 11, wherein the total concentration of the hydroxide in the electrolyte is greater than 7M and less than 10M.

14. 12. The battery of claim 11, wherein the total concentration of the hydroxide in the electrolyte is greater than 7.5M and less than 9.5M.

15. 12. The battery of claim 11, wherein the electrolyte comprises KOH.

16. 12. The battery of claim 11, wherein the electrolyte comprises at least 0.05M LiOH.

17. The electrolyte is KOH, NaOH, LiOH, RbOH, CsOH, FrOH, Be(OH) ２ , Ca(OH) ２ , Mg(OH) ２ , Sr(OH) ２ , Ra(OH) ２ , Ba(OH) ２ and mixtures thereof.

18. 12. The battery of claim 11, wherein the electrolyte comprises a sulfide.

19. adding an additive to the anode and / or electrolyte of the battery to reduce migration of sulfides to the positive electrode or to consume sulfides or sulfates released from said anode; and / or adding an anion selective membrane or separator to the battery to prevent migration of specific ions; A method comprising:

20. 20. The method of claim 19, wherein the additive and / or the anion selective membrane or the separator comprises lignin and its derivatives.

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