Electrode configurations for iron-air electrochemical systems

Abstract

An iron-air battery includes: an iron electrode in contact with an anode current collector, where the iron electrode includes a plurality of channels; an oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposing second surface in contact with air; the oxygen evolution reaction electrode and the multiple channels of the iron electrode are inserted in a staggered mode, and at least one part of the oxygen evolution reaction electrode is arranged in the multiple channels in the direction perpendicular to the plane of the oxygen reduction reaction electrode; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority of U.S. Provisional Application No. 63 / 379,223, filed on October 12, 2022, and all benefits derived therefrom under 35 U.S.C.§119. The entire content of the U.S. Provisional Application is incorporated herein by reference. Background Art

[0003] Energy storage technologies are playing an increasingly important role in the power grid; at the most basic level, these energy storage assets provide a smoothing function to better match power generation and demand in the grid. The services performed by energy storage devices are beneficial to the power grid on multiple time scales from milliseconds to years. Nowadays, existing energy storage technologies can support time scales from milliseconds to hours, but there is a need for energy storage systems with long - duration and ultra - long - duration (collectively referred to as > 8h).

[0004] Iron - containing negative - electrode electrochemical systems (or, in other words, iron - containing anode electrochemical systems) are attractive options for electrochemical energy storage. There is a need to improve the design and composition of electrochemical systems with iron - containing materials, such as iron - containing negative electrodes, to enhance the performance of such systems. Summary of the Invention

[0005] Provided is an iron - air battery, comprising: an iron electrode in contact with an anode current collector, wherein the iron electrode comprises a plurality of channels; an oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air; an oxygen evolution reaction electrode interleaved with the plurality of channels of the iron electrode, wherein at least a portion of the oxygen evolution reaction electrode is disposed within the plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode.

[0006] Provided is an iron - air battery, comprising: an iron electrode comprising a plurality of anodes separated by a plurality of channels, wherein the plurality of anodes are electrically connected to each other; an oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air; an oxygen evolution reaction electrode interleaved with the plurality of channels, wherein at least a portion of the oxygen evolution reaction electrode is disposed within the plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode.

[0007] Provided is an iron-air battery, comprising: an iron electrode including a plurality of anodes separated by a plurality of channels, wherein the plurality of anodes are electrically connected to each other; an oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air; an oxygen evolution reaction electrode including a plurality of cathodes interleaved with the plurality of anodes, wherein the plurality of cathodes are disposed in the plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode, and wherein the plurality of cathodes are electrically connected to each other; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode.

[0008] Provided is an iron-air battery, comprising: an iron electrode in contact with an anode current collector, wherein the iron electrode includes a plurality of channels; an oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air; an oxygen evolution reaction electrode including a plurality of cathodes interleaved with the iron electrode, wherein the plurality of cathodes are disposed in the plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode, and wherein the plurality of cathodes are electrically connected to each other; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode.

[0009] Provided is an iron-air battery, comprising: an iron electrode in contact with an anode current collector, wherein the iron electrode and the anode current collector are arranged in a spiral configuration; an oxygen reduction reaction electrode having a first surface facing the axis of rotation of the spiral configuration and an opposite second surface in contact with air; an oxygen evolution reaction electrode arranged in a spiral configuration and interleaved with the iron electrode, wherein the iron electrode and the oxygen evolution reaction electrode are at least partially double-stranded; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, and the oxygen evolution reaction electrode.

[0010] Provided is an iron-air battery, comprising: an iron electrode in contact with an anode current collector, wherein the iron electrode and the anode current collector are arranged in a corrugated configuration; and wherein the iron electrode includes a plurality of channels between the corrugations; an oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air; an oxygen evolution reaction electrode interleaved with the plurality of channels of the iron electrode, wherein at least a portion of the oxygen evolution reaction electrode is disposed in the plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode; and wherein the oxygen evolution reaction electrode is arranged in a corrugated configuration; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode.

[0011] Provided is a method of forming an iron-air battery, comprising: forming an iron negative electrode material onto an anode current collector to form an iron electrode including a plurality of channels; disposing an oxygen evolution reaction electrode into one or more of the channels of the iron electrode; and assembling an oxygen reduction reaction electrode having a first surface facing the iron electrode and an opposite second surface in contact with air to form an electrode assembly.

[0012] The above and other features are illustrated by the following drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The following drawings are exemplary embodiments, in which like elements are identically numbered.

[0014] Figure 1 is a schematic cross-sectional view of an iron-air battery;

[0015] Figure 2 is a schematic cross-sectional view of an iron-air battery according to one or more embodiments;

[0016] Figure 3 is a schematic cross-sectional view of an iron-air battery according to one or more embodiments;

[0017] Figure 4 is a schematic cross-sectional view of an iron-air battery according to one or more embodiments;

[0018] Figure 5 is a schematic cross-sectional view of an iron-air battery according to one or more embodiments;

[0019] Figure 6 is a schematic cross-sectional view of an iron-air battery according to one or more embodiments;

[0020] Figure 7 is a schematic cross-sectional view of an iron-air battery according to one or more embodiments;

[0021] Figure 8 is according to one or more embodiments Figure 7 perspective view of the iron-air battery;

[0022] Figure 9 is a schematic cross-sectional view of an iron-air battery according to one or more embodiments;

[0023] Figure 10 is a schematic cross-sectional view of an iron-air battery according to one or more embodiments;

[0024] Figure 11 is according to one or more embodiments Figure 10 perspective view of the iron-air battery;

[0025] Figure 12 is a schematic cross-sectional view of an iron-air battery according to one or more embodiments;

[0026] Figure 13 is a schematic cross-sectional view of an iron-air battery according to one or more embodiments;

[0027] Figure 14 is a schematic cross-sectional view of an iron-air battery according to one or more embodiments;

[0028] Figure 15 is a schematic cross-sectional view of an iron-air battery according to one or more embodiments;

[0029] Figure 16 is a perspective view of an iron-air battery according to one or more embodiments;

[0030] Figure 17 is a perspective view of an iron-air battery according to one or more embodiments;

[0031] Figure 18 shows an exemplary method for fabricating an iron-air battery according to one or more embodiments;

[0032] Figure 19 is a graph of Coulombic efficiency (%) versus charge time (hours, h) according to one or more embodiments;

[0033] Figure 20 is a graph of areal specific resistance (ohm square centimeter, Ω cm 2 ) versus time (h);

[0034] Figure 21 is a graph of Coulombic efficiency (%) versus charge time (h) according to one or more embodiments;

[0035] Figure 22 is a graph of areal specific resistance (Ω cm 2 ) versus time (h);

[0036] Figure 23 is a graph of Coulombic efficiency (%) versus charge time (h) according to one or more embodiments;

[0037] Figure 24 is a graph of areal specific resistance (Ω cm 2 ) versus time (h);

[0038] Figure 25 is a graph of Coulombic efficiency (%) versus charge time (h) according to one or more embodiments; and

[0039] Figure 26 is a graph of areal specific resistance (Ω cm 2 ) versus time (h); and

[0040] Figure 27is a graph showing the relationship between battery voltage (volts, V) and capacity (ampere-hours, Ah) according to one or more embodiments. Detailed Description

[0041] An electrochemical cell, such as a battery, stores electrochemical energy by generating a voltage difference between a positive electrode and a negative electrode using an electrochemical potential difference. If 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 through external and internal resistance elements. Typically, the external element conducts electrons, and the internal element (electrolyte) conducts ions. Since charge imbalance cannot be maintained between the negative and positive electrodes, these two flow streams must provide ions and electrons at the same rate. In operation, the electric current can be used to drive an external device. A rechargeable battery can be charged by applying an opposite voltage difference that drives the electric current and the ion current in a direction opposite to that of the discharging battery in use.

[0042] A metal-air battery is an electrochemical cell that includes a metal anode, a cathode exposed to air, and an aqueous or aprotic or solid electrolyte. During discharge of the metal-air battery, a reduction reaction occurs at the cathode, and the metal anode is oxidized. Recently, there has been an increased interest in developing iron-air batteries because of their potential to provide grid-scale energy storage. Additionally, the main raw material of iron-air batteries is iron oxide, which is a material with abundant reserves, low cost, non-toxicity, and economy.

[0043] The half-cell reaction on the iron anode during discharge and oxidation in an alkaline electrolyte is as follows

[0044] Equation 1 and Equation 2 provide:

[0045]

[0046] In Equation 1, iron hydroxide can form on the surface of the iron that forms the iron electrode 120. In Equation 2, the iron hydroxide is then further oxidized to form magnetite. During discharge, a net volume increase is absorbed in the porosity of the iron anode 120. According to the anode reaction in this example, the theoretical capacity based on metallic iron is 960 milliamperes-hour per gram of Fe (mAh / g) in Step 1 and 320 mAh / g per gram of Fe in Equation 2.

[0047] Due to competition with hydrogen (H 2 ) evolution, the iron anode may be difficult to charge, which is a side reaction that does not result in battery charging because electrons are transferred to H 2, rather than being stored in a more reducible iron negative electrode. Additionally, the ability of electrons or ions to pass through a thick iron anode may also impede the charge and discharge reactions. When there is no or only limited access for electrons or ions to pass through the anode, the charge and discharge efficiency of the anode may be reduced. Therefore, an improved iron-air battery is needed.

[0048] To reduce the material cost of an iron-air battery, an iron electrode with a high areal capacity, i.e., a thick iron electrode, may be desirable. Assuming the cost of the air electrode is fixed, a thicker iron electrode may mean that the material cost of the air electrode is divided by a larger battery energy. However, compared to a thinner iron electrode, a thicker iron electrode may have a lower Coulombic efficiency and a lower voltage efficiency. Therefore, a design that can provide a high areal capacity and an iron electrode (such as a thicker iron electrode) with improved Coulombic and voltage efficiencies may be beneficial.

[0049] A thicker iron electrode has a lower voltage efficiency because a thicker iron electrode has a higher ionic resistance. A thicker iron electrode has a higher resistance because ions in the electrolyte must travel farther to reach the back of the electrode.

[0050] Hydrogen evolution may occur as a side reaction on the iron electrode, which makes the Coulombic efficiency less than 100%. A thicker iron electrode may have a lower Coulombic efficiency because current flows into the path of least resistance. The resistance of hydrogen evolution at the front of the electrode is lower compared to the resistance of the ionic current flowing to the back of the thick iron electrode.

[0051] Figure 1 An iron-air electrochemical cell including a dual-electrode configuration is shown. As used herein, the term "dual-electrode configuration" refers to an iron-air battery having separate positive electrodes for charging and discharging. When oxygen is the reactant at the positive electrode, it may be advantageous to have separate electrodes for discharging and for charging. Referring to Figure 1 , an iron-air electrochemical cell 100 is provided. The iron-air battery 100 includes a current collector 101, an iron electrode 102 (anode) disposed on the current collector 101, an oxygen reduction reaction (ORR) electrode 104, and an oxygen evolution reaction (OER) electrode 106. The iron-air battery 100 may further include a separator 108 disposed between the iron electrode 102 and the OER electrode 106. The separator 108 may include a compression frame, a porous insulator, and / or a ribbed structure to facilitate the expulsion of bubbles from the iron electrode 102. For example, the separator 108 may be a porous dielectric coating formed on the iron electrode 102 and / or the OER electrode 106. The iron-air electrochemical cell further includes an electrolyte 110 in contact with the iron electrode, the first surface of the ORR electrode 104, and the OER electrode 106. Suitable electrolytes are further described herein.

[0052] During charging of the iron-air electrochemical cell 100, the OER electrode 106 and the iron electrode 102 can be electrically connected to a power source 112 such that the iron species of the iron electrode 102 are reduced to form metallic iron Fe(0). During discharging of the iron-air electrochemical cell 100, the ORR electrode 104 and the iron electrode 102 can be electrically connected to a load 114 such that the metallic iron Fe(0) of the iron electrode 102 is oxidized to form higher-valent iron species, such as Fe 3 O 4 . The iron-air electrochemical cell 100 can also be configured to include a switch 116 to permit electrical connection between the iron electrode 102 and the power source 112, or to permit electrical connection between the iron electrode 102 and the load 114.

[0053] The coulombic efficiency of the iron electrode during charging can be affected by the construction of the electrodes used for charging. The applicant has found that the coulombic efficiency can be improved by reducing the distance that ions must travel through the iron electrode to reach unreacted iron oxide species therein. The various embodiments described herein provide an iron anode and an OER electrode having an interdigitate or channel design to provide higher voltage efficiency and higher coulombic efficiency than a simple planar electrode arrangement, such as Figure 1 the arrangement shown in. For example, in any porous iron electrode, there may be competing requirements for ion transport (the higher the porosity, the better) and electrical transport across particle-particle contacts (the lower the porosity, generally the better). Without wishing to be bound by theory, a key advantage of the interdigitate or channel electrode design may be that these two functions are decoupled: ion transport occurs in the channels, while good electrical contact between the active material particles can occur in the lower porosity features of the iron anode.

[0054] According to one aspect, there is provided an iron-air battery including an iron electrode in contact with an anode current collector, wherein the iron electrode includes a plurality of channels. The iron-air battery includes an oxygen reduction reaction (ORR) electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air. The iron-air battery includes an oxygen evolution reaction (OER) electrode interdigitated with the plurality of channels of the iron electrode, wherein at least a portion of the oxygen evolution reaction electrode is disposed within the plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode. The iron-air battery further includes an electrolyte in contact with the iron electrode, the first surface of the ORR electrode, the plurality of channels, and the OER electrode.

[0055] Figure 2 One or more embodiments of an iron-air battery 200 are shown. The iron-air battery 200 includes an iron electrode 202 in contact with an anode current collector 201. As Figure 2As shown in , the iron-air battery 200 includes a plurality of channels 220 disposed therein. When viewed in cross-section, the channels 220 can have any suitable shape, such as a rectangular prism, a cylinder, a pyramid shape, a trapezoidal prism shape, etc. Each of the channels 220 can have the same shape or different shapes.

[0056] In the iron electrode 202, one or more of the plurality of channels 220 can have an average length 216 of 3 mm to 50 mm in a direction perpendicular to the plane of the ORR electrode 204. For example, one or more of the plurality of channels 220 can have an average length 216 of 15 mm to 35 mm, or 15 mm to 30 mm, or 15 mm to 25 mm in a direction perpendicular to the plane of the ORR electrode 204.

[0057] In the iron electrode 202, one or more of the plurality of channels 220 can have an average width 218 of 1 mm to 40 mm in a direction parallel to the plane of the ORR electrode 204. For example, one or more of the plurality of channels 220 can have an average width of 2 mm to 30 mm, or 2 mm to 20 mm, or 2 mm to 15 mm in a direction parallel to the plane of the ORR electrode 204.

[0058] In the iron electrode 202, when measured between the centers of adjacent channels, one or more of the plurality of channels 220 can be spaced apart from each other by an average distance 222 of 10 mm to 50 mm in a direction parallel to the plane of the ORR electrode 204. For example, when measured between the centers of adjacent channels, one or more of the plurality of channels 220 can be spaced apart from each other by an average distance 222 of 10 mm to 30 mm, or 10 mm to 20 mm in a direction parallel to the plane of the ORR electrode 204.

[0059] In some embodiments, and as further described herein, the plurality of channels can be oriented perpendicular to the plane of the ORR electrode, i.e., can have a channel width that is constant across the electrode thickness. Alternatively, the plurality of channels can be inclined. If the plurality of channels are inclined, the channels can be wider at the side facing the ORR electrode, as described herein. In other embodiments, if the plurality of channels are inclined, the slope can be opposite, where the channels are narrower at the side facing the ORR electrode. The plurality of channels can be vertically oriented to allow hydrogen evolution reaction (HER) / oxygen evolution reaction (OER) bubbles to escape from the top of the battery, as shown below. In other embodiments, the channels can be horizontal, cross-hatched, etc.

[0060] In Figure 2In [reference], the iron-air battery 200 includes an ORR electrode 204 having a first surface 204a facing a plurality of channels 220 and an opposite second surface 204b in contact with air. The ORR electrode 204 may be as defined herein.

[0061] In Figure 2 [reference], the iron-air battery 200 includes an OER electrode 206 interleaved with a plurality of channels 220 of the iron electrode 202, wherein at least a portion of the OER electrode 206 is disposed within the plurality of channels 220 in a direction perpendicular to the plane of the ORR electrode 204. In other words, the OER electrode 206 has a portion disposed within the channels 220 in a direction perpendicular to the first surface 204a of the ORR electrode 204.

[0062] The iron electrode 202 may include a ridge portion parallel to the current collector 201 that connects the protruding portions of the iron electrode 202 that define the plurality of channels 220. Such protruding portions of the iron electrode 220 may be referred to herein as "ribs", while the non-protruding portions of the iron electrode 220 may be referred to herein as "ridges". The ridge portion may include an electrolyte volume fraction that is 2 volume % (vol%) to 20 volume % (such as 5 volume % to 15 volume %) lower than that of the rib portion. The ridge portion and the rib portion may be formed of the same iron-containing material. The thickness of the ridge portion may be 10% to 50% of the thickness of the rib portion, where the thickness direction is defined as parallel to the plurality of channels 220.

[0063] In some embodiments, the ridge portion may have a higher density and / or a lower porosity than the rib portion. For example, the porosity of the ridge portion may be at least 5 volume % less than the porosity of the rib portion. The binding of the electrode material in the ridge portion to the more dense current collector may improve adhesion. Additionally, the ridge portion is thinner than the rib portion, and thus the need to achieve high ion transport in the ridge portion relative to the rest of the iron electrode may be reduced. Therefore, the ridge portion may require a higher degree of compaction and / or a lower porosity relative to the rib portion. The porosity / compaction gradient may be continuous or may include discrete changes in porosity / compaction. The gradient of porosity is caused by the manufacturing method employed.

[0064] In other embodiments, the ridge portion and the rib portion can have substantially the same porosity and / or density in the fully charged and fully discharged states (e.g., the powder microstructure of the ridge portion and the rib portion can be uniform). For example, the porosity / density of the ridge portion can be within + / - 5% of the porosity / density of the rib portion. This design can provide a uniform transfer resistance in all regions of the iron electrode. Electrodes with non-uniform resistance may have poor Coulomb efficiency. Uniform electrode porosity can be achieved by sintering the filled electrode powder, metal injection molding, or any suitable method common in the art for assembling large amounts of powder materials and thermally or mechanically binding them together uniformly, as described further below. In some cases, the gel powder mass can be shaped by coating, dried, and then processed to form the iron electrode. In some embodiments, the binding of the powder can be performed by electrochemical sintering rather than by mechanically driven and / or thermally driven consolidation. In some embodiments, the binding of the powder can be achieved by combining with an adhesive material (such as a polymer adhesive) and then extruding, compressing, or otherwise forming the iron electrode.

[0065] In Figure 2 , the iron-air battery 200 further includes an electrolyte 210 that contacts the iron electrode 202, the first surface 204a of the ORR electrode 204, the plurality of channels 220, and the OER electrode 206. The electrolyte 210 is as described herein.

[0066] In some embodiments, the iron-air battery 200 can further include a spacer (not shown) disposed between at least a portion of the iron electrode 202 and the OER electrode 206. For example, the spacer can be disposed along each of the channels 220 of the iron electrode 202. The spacer material can be as described herein. In some embodiments, the region between the negative electrode and the OER electrode can include a frame for compression, a porous insulator as a spacer, and / or a ribbed structure that facilitates bubble expulsion. These features and materials will be further described herein.

[0067] As Figure 2 shown, the OER electrode 206 can include a backbone portion disposed between the iron electrode 202 and the ORR electrode 204, and a plurality of cathode protrusions 208 that extend from the backbone portion and are disposed within the plurality of channels 220 of the iron electrode 202. The backbone portion of the OER electrode 206 does not interleave with the plurality of channels 220 of the iron electrode 202. For example, the backbone portion of the OER electrode 206 can be parallel to the ORR electrode 204. The cathode protrusions 208 can have any suitable shape, and the cross-section can be, for example, a rectangular prism (e.g., box-shaped), a triangle (e.g., pyramid-shaped), a trapezoidal prism, an ellipse (e.g., cylindrical), etc.

[0068] In some embodiments, when measured from the backbone portion, the plurality of cathode protrusions 208 may have an average length 212 of from 3 millimeters (mm) to 50 mm. For example, when measured from the backbone portion, the plurality of cathode protrusions 208 may have an average length 212 of from 5 mm to 35 mm, or from 10 mm to 30 mm. In some embodiments, when measured in a direction parallel to the backbone portion, the plurality of cathode protrusions 208 may have a width of from 0.1 mm to 20 mm, or from 0.5 mm to 15 mm.

[0069] In some embodiments, more than 25% of the channels of the iron electrode include an OER electrode disposed therein. That is, some of the channels of the iron electrode may include an OER electrode, and some channels of the iron electrode may not include an OER electrode. As Figure 3 shown, one or more channels 220 may be without an OER electrode 206, where the OER electrode 206 is found to be located in a portion of the channels 220 of the iron electrode 202. For example, more than 40%, or more than 50%, or more than 60% of the channels of the iron electrode may include an OER electrode disposed therein.

[0070] In some embodiments, Figure 2 one or more of the plurality of channels in may also include an additive, as described herein. In some embodiments, a channel may include an additive without including an OER electrode disposed therein. In other embodiments, a channel may include both an additive and an OER electrode disposed therein.

[0071] The OER electrode may be bent or folded to conform to the profile of the iron electrode such that branches of the OER electrode are disposed closely adjacent within the plurality of channels of the iron electrode. In some embodiments, the iron-air battery may include an OER electrode disposed in a corrugated configuration within the plurality of channels. As Figure 4 shown, the OER electrode 206 may be disposed in a corrugated configuration within the plurality of channels 220. In the corrugated configuration, the plurality of cathode protrusions 208 are disposed in a continuous manner, extending from the backbone portion of the OER electrode 206 into the plurality of channels 220 rather than as protrusions from a core backbone portion.

[0072] Now referring to Figure 3 , the iron-air battery 300 may include a current collector 201 that further includes one or more branch current collectors 201a disposed parallel to the plurality of channels 220 in a direction perpendicular to the ORR electrode 204. In this arrangement, the main current collector 201 is connected to the one or more branch current collectors 201a, where the main current collector is disposed parallel to the ORR electrode 204. Although Figure 3The combination of the branched current collector 201a with another feature is shown, but it is contemplated that one or more branched current collectors 201a may be disposed within the iron electrode 202 in one or more portions parallel to the plurality of channels 220.

[0073] The plurality of channels may be inclined (e.g., having a V-shaped or trapezoidal cross-section and sidewalls extending in a plane not perpendicular to the plane of the first ORR electrode and / or the second ORR electrode). Alternative configurations may include negatively inclined sidewalls of the channels (e.g., having an inverted V-shaped or trapezoidal cross-section and sidewalls extending in a plane not perpendicular to the plane of the first ORR electrode and / or the second ORR electrode). However, in other embodiments, the channels may be non-inclined (e.g., may have a rectangular cross-section and sidewalls extending in a plane orthogonal to the plane of the first ORR electrode and / or the second ORR electrode).

[0074] In some embodiments, one or more of the channels may have a trapezoidal shape, as Figure 5 shown. In Figure 5 the width of the channel 220 measured at the point closest to the ORR electrode 204 is wider than the width of the channel 220 measured at the point farthest from the ORR electrode 204. For example, one or more of the plurality of channels 220 have an average width of 1 mm to 40 mm in a direction parallel to the plane of the ORR electrode 204, wherein a first width "a" closest to the ORR electrode is 1% to 500% greater than a second width "b" farthest from the ORR electrode.

[0075] Figure 5 An embodiment is shown in which the iron-air battery 500 may further include a spacer 209 disposed between at least a portion of the iron electrode 202 and the OER electrode 206. It should be noted that a spacer may be included in any of the embodiments described herein, wherein the spacer is disposed between at least a portion of the iron electrode and the OER electrode. The spacer is as described herein.

[0076] Figure 5 An embodiment is shown in which the OER electrode 206 is disposed within the plurality of channels 220 in a corrugated configuration. However, other configurations for the OER electrode 206 are contemplated, including a plurality of OER electrode branches extending from a central OER electrode trunk portion.

[0077] In some embodiments, the central anode current collector may have iron electrodes disposed on either side thereof to provide electrochemical cells replicated across the anode current collector. As Figure 6As shown, the anode current collector 201 may include a first surface 201a and an opposite second surface 201b. The iron electrode may include a first iron electrode 202a located on the first surface 201a of the current collector 201 and a second iron electrode 202b located on the second surface 201b of the current collector 201, wherein the first iron electrode 202a includes a first plurality of channels 220a, and the second iron electrode 202b includes a second plurality of channels 220b.

[0078] In Figure 6 it, the ORR electrode (first ORR electrode) 204a has a first surface facing the first plurality of channels 220a and an opposite second surface in contact with air. Additionally, the iron-air battery 600 further includes a second ORR electrode 204b having a first surface facing the second plurality of channels 220b and an opposite second surface in contact with air. The first ORR electrode 204a and the second ORR electrode 204b may be disposed on opposite sides of the iron electrode and equidistant from the iron electrode.

[0079] In Figure 6 it, the OER electrode (first OER electrode) 206a is interleaved with the first plurality of channels 220a of the first iron electrode 202a, wherein at least a portion of the OER electrode 206a is disposed within the first plurality of channels 220a in a direction perpendicular to the plane of the first ORR electrode 204a. Additionally, the iron-air battery 600 further includes a second OER electrode 206b that is interleaved with the second plurality of channels 220b of the second iron electrode 202b, wherein at least a portion of the second OER electrode 206b is disposed within the second plurality of channels 220b in a direction perpendicular to the plane of the second ORR electrode 204b.

[0080] In Figure 6 it, the iron-air battery 600 further includes an electrolyte (first electrolyte) 210a that contacts the first iron electrode 202a, the first surface of the first ORR electrode 204a, the first plurality of channels 220a, and the first OER electrode 206a. The first electrolyte 210a is as described herein. The iron-air battery 600 further includes a second electrolyte 210b that contacts the second iron electrode 202b, the first surface of the second ORR electrode 204b, the second plurality of channels 220b, and the second OER electrode 206b. The second electrolyte 210b is as described herein. The first electrolyte and the second electrolyte are the same or different.

[0081] The first plurality of channels 220a and the second plurality of channels 220b may be aligned with each other across the current collector 201, as Figure 6 shown. However, in other embodiments, the first plurality of channels 220a and the second plurality of channels 220b may be offset from each other with respect to the current collector 201.

[0082] In addition to rectangular prisms, the plurality of channels can have other geometries. As Figure 7 shown, the anode current collector 201 can include a first surface 201a and an opposite second surface 201b. The iron electrode can include a first iron electrode 202a located on the first surface 201a of the current collector 201 and a second iron electrode 202b located on the second surface 201b of the current collector 201, wherein the first iron electrode 202a includes a first plurality of channels 220a, and the second iron electrode 202b includes a second plurality of channels 220b.

[0083] In Figure 7 , the ORR electrode (first ORR electrode) 204a has a first surface facing the first plurality of channels 220a and an opposite second surface in contact with air. Additionally, the iron-air battery 600 further includes a second ORR electrode 204b having a first surface facing the second plurality of channels 220b and an opposite second surface in contact with air.

[0084] In Figure 7 , the OER electrode (first OER electrode) 206a is interleaved with the first plurality of channels 220a of the first iron electrode 202a, wherein at least a portion of the OER electrode 206a is disposed within the first plurality of channels 220a in a direction perpendicular to the plane of the first ORR electrode 204a. Additionally, the iron-air battery 600 further includes a second OER electrode 206b that is interleaved with the second plurality of channels 220b of the second iron electrode 202b, wherein at least a portion of the second OER electrode 206b is disposed within the second plurality of channels 220b in a direction perpendicular to the plane of the second ORR electrode 204b.

[0085] The first plurality of channels 220a and the second plurality of channels 220b can be aligned with each other across the current collector 201, as Figure 7 shown. However, in other embodiments, the first plurality of channels 220a and the second plurality of channels 220b can be offset from each other relative to the current collector 201.

[0086] Figure 8 is Figure 7 an isometric view of the iron-air battery. In Figure 8 , the anode tab 230 is shown connected to the current collector 201. Additionally, the cathode tab 240a is shown connected to the first OER electrode 206a, and the cathode tab 240b is shown connected to the second OER electrode 206b.

[0087] In some embodiments, the plurality of electrochemical cells can be arranged such that the central channels between the cells can be in contact with air. AsFigure 9 as shown in Figure 2 The iron-air battery shown in Figure 2 can be replicated across air channels that flow between the batteries. The iron-air battery 900 further includes a second iron electrode 302 that contacts a second anode current collector 301, wherein the second iron electrode 302 includes a second plurality of channels 320. The iron-air battery 900 includes a second ORR electrode 304 that has a first surface facing the second plurality of channels 320 and an opposite second surface that contacts air. As described above, an air channel 330 is disposed between the second surface of the first ORR electrode 204 and the second surface of the second ORR electrode 304.

[0088] In Figure 9 In Figure 9 , a second OER electrode 306 is interleaved with the second plurality of channels 320 of the second iron electrode 302, wherein at least a portion of the second OER electrode 306 is disposed within the second plurality of channels 320 in a direction perpendicular to the plane of the second ORR electrode 304.

[0089] The iron-air battery 900 further includes a second electrolyte 310 that contacts the second iron electrode 302, the first surface of the second ORR electrode 304, the second plurality of channels 320, and the second OER electrode 306. The (first) electrolyte 210 may be the same as or different from the second electrolyte 310. In some embodiments, the first electrolyte and the second electrolyte may be in fluid communication with each other.

[0090] As described herein, the plurality of channels may have other geometric shapes than a rectangular prism, wherein the plurality of electrochemical cells are arranged such that a central channel between the cells can contact air. As Figure 10 as shown in Figure 5 The iron-air battery shown in Figure 5 can be replicated across air channels that flow between the batteries. The iron-air battery 1000 further includes a second iron electrode 302 that contacts a second anode current collector 301, wherein the second iron electrode 302 includes a second plurality of channels 320. The iron-air battery 1000 includes a second ORR electrode 304 that has a first surface facing the second plurality of channels 320 and an opposite second surface that contacts air. An air channel 330 is disposed between the second surface of the first ORR electrode 204 and the second surface of the second ORR electrode 304.

[0091] In Figure 10 In Figure 10 , a second OER electrode 306 is interleaved with the second plurality of channels 320 of the second iron electrode 302, wherein at least a portion of the second OER electrode 306 is disposed within the second plurality of channels 320 in a direction perpendicular to the plane of the second ORR electrode 304.

[0092] The iron-air battery 1000 further includes a second electrolyte 310 that contacts the second iron electrode 302, the first surface of the second ORR electrode 304, the second plurality of channels 320, and the second OER electrode 306. The (first) electrolyte 210 may be the same as or different from the second electrolyte 310. In some embodiments, the first electrolyte and the second electrolyte may be in fluid communication with each other.

[0093] Figure 11 Is Figure 10 An isometric view 1100 of an iron-air battery. In Figure 11 it, the anode tab 230 is shown connected to the corresponding current collectors 201, 301. Additionally, the cathode tab 240a is shown connected to the first OER electrode 206, and the cathode tab 240b is shown connected to the second OER electrode 306.

[0094] In another aspect, there is provided an iron-air battery, comprising: an iron electrode including a plurality of anodes separated by a plurality of channels, wherein the plurality of anodes are in electrical communication with each other; an ORR electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air; an OER electrode interleaved with the plurality of channels, wherein at least a portion of the OER electrode is disposed within the plurality of channels in a direction perpendicular to the plane of the ORR electrode; and an electrolyte in contact with the iron electrode, the first surface of the ORR electrode, the plurality of channels, and the OER electrode.

[0095] Figure 12 One or more embodiments of an iron-air battery 1200 are shown. The iron-air battery 1200 includes an iron electrode that includes a plurality of anodes 402 separated by a plurality of channels 420, wherein the plurality of anodes 402 are in electrical communication with each other. For example, the plurality of anodes 402 may be connected by a bus bar or a current collector 401. As Figure 12 shown, the plurality of channels 420 are disposed between the plurality of anodes 402. The anodes 402 may have any suitable shape, and thus the shape of the channels 420 will correspond to the shape of the adjacent anodes 402 that define the channels 420. Each anode 402 may have the same shape or different shapes, and thus each channel 420 may have the same shape or different shapes.

[0096] One or more of the plurality of anodes 402 may have an average length of 3 mm to 50 mm in a direction perpendicular to the plane of the ORR electrode 404. For example, one or more of the plurality of anodes 402 may have an average length of 15 mm to 35 mm, or 15 mm to 30 mm, or 15 mm to 25 mm in a direction perpendicular to the plane of the ORR electrode 404.

[0097] In the iron-air battery 1200, the anodes among the plurality of anodes may have an average width of 1 mm to 40 mm in a direction parallel to the plane of the ORR electrode 404. For example, the anodes among the plurality of anodes 402 may have an average width of 2 mm to 30 mm, or 2 mm to 20 mm, or 2 mm to 15 mm in a direction parallel to the plane of the ORR electrode 404.

[0098] In the iron-air battery 1200, the anodes among the plurality of anodes 402 may be spaced apart from each other by an average distance of 10 mm to 50 mm in a direction parallel to the plane of the ORR electrode 404. For example, when measured between the centers of adjacent anodes, one or more of the plurality of anodes 404 may be spaced apart from each other by an average distance of 10 mm to 30 mm, or 10 mm to 20 mm in a direction parallel to the plane of the ORR electrode 404.

[0099] In Figure 12 the iron-air battery 1200 may further include a current collector 401, wherein the plurality of anodes 402 are in contact with the anode current collector 401. In other embodiments, the anode current collector 401 may be replaced by a bus bar (not shown) connected to each of the plurality of anodes 402.

[0100] In Figure 12 the iron-air battery 1200 includes an ORR electrode 404 having a first surface facing the plurality of channels 420 and an opposite second surface in contact with air. The ORR electrode 404 may be as defined herein.

[0101] In Figure 12 the iron-air battery 1200 includes an OER electrode 406 that is interleaved with the plurality of channels 420 of the iron electrode, wherein at least a portion of the OER electrode 406 is disposed within the plurality of channels 420 in a direction perpendicular to the plane of the ORR electrode 404. Thus, the OER electrode 406 has a portion disposed in the channels 420 in a direction perpendicular to the first surface of the ORR electrode 404 such that the OER electrode 406 is interleaved with the plurality of anodes 402.

[0102] In Figure 12 the iron-air battery 1200 further includes an electrolyte 410 in contact with the plurality of anodes 402, the first surface of the ORR electrode 404, the plurality of channels 420, and the OER electrode 406. The electrolyte 410 is as described herein.

[0103] In some embodiments, the iron-air battery 1200 may further include a spacer (not shown) disposed between at least a portion of the anode 402 and the OER electrode 406. For example, the spacer may be disposed between the anode 402 and the OER electrode 406 in each of the channels 420. The spacer material may be as described herein.

[0104] As Figure 12 shown, the OER electrode 406 may include a main body portion disposed between the plurality of anodes 402 and the ORR electrode 404, and a plurality of cathode protrusions 406a extending from the main body portion and disposed within the plurality of channels 420 between the plurality of anodes 402. The main body portion of the OER electrode 406 does not intersect and interleave with the plurality of channels 420 between the plurality of anodes 402. For example, the main body portion of the OER electrode 406 may be parallel to the ORR electrode 404. The cathode protrusions 406a may have any suitable shape, and the cross-section may be, for example, rectangular (e.g., box-shaped), triangular (e.g., pyramid-shaped), trapezoidal, elliptical (e.g., cylindrical), etc.

[0105] In some embodiments, when measured from the main body portion, the plurality of cathode protrusions 406a may have an average length of 3 mm to 50 mm. For example, when measured from the main body portion, the plurality of cathode protrusions 406a may have an average length of 5 mm to 35 mm, or 10 mm to 30 mm. In some embodiments, when measured in a direction parallel to the main body portion, the plurality of cathode protrusions 406a may have a width of 0.1 mm to 20 mm, or 0.5 mm to 15 mm.

[0106] The iron-air battery 1200 may include a current collector 401, which further includes one or more branch current collectors 401a disposed parallel to the plurality of channels 420 in a direction perpendicular to the ORR electrode 404. In this arrangement, the main current collector 401 is connected to the one or more branch current collectors 401a, wherein the main current collector is disposed parallel to the ORR electrode 404. In some embodiments, the branch current collector 401a may be electrically connected to a bus bar, for example, connected to a bus bar disposed above or below the plane of the plurality of anodes 402. In some embodiments, each anode of the plurality of anodes 402 is in contact with the branch current collector 401a, wherein each branch current collector 401a is connected to a main current collector 401 disposed parallel to the first surface of the ORR electrode 404. For example, each anode of the plurality of anodes 402 may be in contact with the branch current collector 401a, wherein each branch current collector 401a is connected to a main current collector 401 disposed parallel to the first surface of the ORR electrode 404, wherein the main current collector 401 is disposed outside the plane defining the active regions of the plurality of anodes 402, the OER electrode 406, and the ORR electrode 404.

[0107] In some embodiments, more than 25% of the plurality of channels 420 include an OER electrode 406 disposed therein. That is, some of the channels of the iron electrode may include an OER electrode, and some of the channels of the iron electrode may not include an OER electrode. As Figure 13 shown, one or more of the plurality of channels 420 may be without an OER electrode 406, where the OER electrode 406 is found to be located in a portion of the channels 420 between the plurality of anodes 402. For example, more than 40%, or more than 50%, or more than 60% of the plurality of channels 420 may include an OER electrode 406, 406a disposed therein.

[0108] In some embodiments, Figure 12 or Figure 13 one or more of the plurality of channels in may further include an additive, as described herein. In some embodiments, the channels 420 may include an additive and not include an OER electrode disposed therein. In other embodiments, the channels 420 may include both an additive and an OER electrode disposed therein.

[0109] In some embodiments, the iron-air battery may have an OER electrode disposed in a serpentine manner between the plurality of anodes. Referring to Figure 14 , the iron-air battery 1400 includes an OER electrode 406 disposed in a serpentine configuration in a plurality of channels 420 between the plurality of anodes 402. When the OER electrode is disposed in a serpentine manner, it may be beneficial to further include a second ORR electrode. In some embodiments, the iron-air battery may further include a second ORR electrode 450 having a first surface facing the plurality of channels 420 and an opposite second surface in contact with air, where the plane of the second ORR electrode 450 is parallel to the plane of the ORR electrode 404.

[0110] The anode 402 of the iron-air battery 1400 further includes a branched current collector 401a disposed parallel to a plurality of channels 420 in a direction perpendicular to the ORR electrode 404. In this arrangement, the branched current collector 401a is electrically connected to a bus bar 445, for example, to a bus bar 445 disposed above (or below) the plane of the plurality of anodes 402. In some embodiments, each of the plurality of anodes 402 includes a branched current collector 401a, wherein each branched current collector 401a is connected to a bus bar 445 disposed parallel to the first surface of the ORR electrode 404. For example, each of the plurality of anodes 402 may be in contact with a branched current collector 401a, wherein each branched current collector 401a is connected to a bus bar 445 disposed parallel to the first surface of the ORR electrode 404, wherein the bus bar 445 is disposed outside the plane defining the active regions of the plurality of anodes 402, the OER electrode 406, and the ORR electrode 404.

[0111] In another aspect, there is provided an iron-air battery, comprising: an iron electrode including a plurality of anodes separated by a plurality of channels, wherein the plurality of anodes are electrically connected to each other; an oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air; an oxygen evolution reaction electrode including a plurality of cathodes interleaved with the plurality of anodes, wherein the plurality of cathodes are disposed in the plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode, and wherein the plurality of cathodes are electrically connected to each other; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode.

[0112] Figure 15 One or more embodiments of an iron-air battery 1500 are shown. The iron-air battery 1500 includes an iron electrode that includes a plurality of anodes 402 separated by a plurality of channels 420, wherein the plurality of anodes 402 are electrically connected to each other. For example, the plurality of anodes 402 may be connected by a bus bar 445. As Figure 15 shown, the plurality of channels 420 are disposed between the plurality of anodes 402. The anodes 402 may have any suitable shape, and thus the shape of the channels 420 will correspond to the shape of the adjacent anodes 402 that define the channels 420. Each anode 402 may have the same shape or different shapes, and thus each channel 420 may have the same shape or different shapes.

[0113] In the iron-air battery 1500, one or more of the plurality of anodes 402 may have an average length of 3 mm to 50 mm in a direction perpendicular to the plane of the ORR electrode 404. For example, one or more of the plurality of anodes 402 may have an average length of 3 mm to 35 mm, or 15 mm to 30 mm, or 15 mm to 25 mm in a direction perpendicular to the plane of the ORR electrode 404.

[0114] In the iron-air battery 1500, the anodes among the plurality of anodes may have an average width of 1 mm to 40 mm in a direction parallel to the plane of the ORR electrode 404. For example, the anodes among the plurality of anodes 402 may have an average width of 2 mm to 30 mm, or 2 mm to 20 mm, or 2 mm to 15 mm in a direction parallel to the plane of the ORR electrode 404.

[0115] In the iron-air battery 1500, the anodes among the plurality of anodes 402 may be spaced apart from each other by an average distance of 10 mm to 50 mm in a direction parallel to the plane of the ORR electrode 404. For example, when measured between the centers of adjacent anodes, one or more of the plurality of anodes 404 may be spaced apart from each other by an average distance of 10 mm to 30 mm, or 10 mm to 20 mm in a direction parallel to the plane of the ORR electrode 404.

[0116] In Figure 15 the iron-air battery 1500 includes an ORR electrode 404 having a first surface facing the plurality of channels 420 and an opposite second surface in contact with air. The ORR electrode 404 may be as defined herein.

[0117] In Figure 15 the iron-air battery includes an OER electrode that includes a plurality of cathodes 506 interleaved with the plurality of anodes 402. The plurality of cathodes 506 are disposed within the plurality of channels 420 in a direction perpendicular to the plane of the ORR electrode 404, and wherein the plurality of cathodes 506 are electrically connected to each other. As described herein, each of the plurality of cathodes 506 may be electrically connected to each other by a bus bar 455. For example, the bus bar 455 may be disposed in a plane above or below the plane defined by the plurality of cathodes 506, the plurality of anodes 402, and the ORR electrode.

[0118] In some embodiments, when measured in a direction perpendicular to the plane of the ORR electrode 404, the plurality of cathodes 506 may have an average length of 3 mm to 50 mm. For example, when measured in a direction perpendicular to the plane of the ORR electrode 404, the plurality of cathodes 506 may have an average length of 5 mm to 35 mm, or 10 mm to 30 mm. In some embodiments, when measured in a direction parallel to the ORR electrode 404, the plurality of cathodes 406 may have a width of 0.1 mm to 20 mm, or 0.5 mm to 15 mm.

[0119] In Figure 15 the iron-air battery 1500 further includes an electrolyte 410 in contact with the plurality of anodes 402, the first surface of the ORR electrode 404, the plurality of channels 420, and the plurality of cathodes 506. The electrolyte 410 is as described herein.

[0120] In some embodiments, the iron-air battery 1500 may further include a separator (not shown) disposed between at least a portion of the plurality of anodes 402 and the plurality of cathodes 506. For example, the separator may be disposed between the anode 402 and the cathode 506 in each of the channels 420. The separator material may be as described herein.

[0121] The iron-air battery 1500 may include one or more branch current collectors 401a disposed parallel to the plurality of channels 420 in a direction perpendicular to the ORR electrode 404. In this arrangement, the bus bar 445 may be connected to the one or more branch current collectors 401a, where the bus bar 445 is disposed parallel to the ORR electrode 404. In some embodiments, the branch current collector 401a may be electrically connected to a bus bar, such as a bus bar disposed above or below the plane of the plurality of anodes 402. For example, where the bus bar 445 is disposed outside the plane defining the active regions of the plurality of anodes 402, the plurality of cathodes 506, and the ORR electrode 404.

[0122] In some embodiments, in the iron-air battery 1500, each of the plurality of cathodes 506 may be in contact with a cathode current collector (e.g., a bus bar), where the cathode current collector may be disposed outside the plane defining the active regions of the plurality of anodes 402, the plurality of cathodes 506, and the ORR electrode 404. The iron-air battery may include a first bus bar or wiring and a second bus bar or wiring, where the first bus bar may be electrically connected to a conductive tab of a current collector branch, and the second bus bar may be electrically connected to a conductive tab of a branch electrode. The first bus bar and the second bus bar may be disposed above the iron electrode and / or the electrolyte.

[0123] In some embodiments, in Figure 15 more than 25% of the channels among the plurality of channels 420 include cathodes among the plurality of cathodes 506 disposed therein. That is, some of the channels 420 between the plurality of anodes 402 may include cathodes among the plurality of cathodes 506, and some of the channels 420 between the anodes of the plurality of anodes 402 may not include an OER electrode (cathode). For example, more than 40%, or more than 50%, or more than 60% of the channels among the plurality of channels 420 may include cathodes among the plurality of cathodes 506 disposed therein.

[0124] In some embodiments, Figure 15One or more of the plurality of channels in [the device] may also include additives, as described herein. In some embodiments, channel 420 may include additives and not include a cathode among the plurality of cathodes 506 disposed therein. In other embodiments, channel 420 may include both additives and a cathode among the plurality of cathodes 506 disposed therein.

[0125] In some embodiments, the iron-air battery 1500 may further include a second ORR electrode 450 having a first surface facing the plurality of channels 420 and an opposite second surface in contact with air, wherein the plane of the second ORR electrode 450 is parallel to the plane of the (first) ORR electrode 404. The first ORR electrode 404 and the second ORR electrode 450 may be disposed on opposite sides of the iron electrode (anode 402) and equidistant from the iron electrode. This dual ORR electrode design can improve discharge uniformity. For example, this design can standardize the conversion of iron oxide and / or hydroxide in different parts of the plurality of anodes 402.

[0126] In some embodiments, a plurality of electrochemical cells may be arranged such that a central channel between the cells may be in contact with air. For example, Figure 15 the iron-air battery of [the device] may be replicated across the air channels flowing between the cells.

[0127] On the other hand, there is provided an iron-air battery including an iron electrode in contact with an anode current collector, wherein the iron electrode includes a plurality of channels as described herein. The iron-air battery includes an ORR electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air, and an OER electrode including a plurality of cathodes interleaved with the iron electrode. The plurality of cathodes are disposed in the plurality of channels in a direction perpendicular to the plane of the OER electrode, and wherein the plurality of cathodes are in electrical communication with each other. The iron-air battery includes an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode. As in Figure 2 the embodiments of [the device], the iron electrode is a monolith having channel portions, and the OER electrode is arranged as a series of cathodes interleaved in the channels, as Figure 15 described in the embodiments of [the device].

[0128] The iron-air battery may include a spacer disposed between at least a portion of the iron electrode and the plurality of cathodes. The spacer may be as described herein.

[0129] On the other hand, an iron-air battery is provided, including: an iron electrode in contact with an anode current collector, wherein the iron electrode and the anode current collector are arranged in a spiral configuration; an oxygen reduction reaction electrode having a first surface facing the axis of rotation of the spiral configuration and a second surface opposite thereto in contact with air; an oxygen evolution reaction electrode arranged in a spiral configuration and interleaved with the iron electrode, wherein the iron electrode and the oxygen evolution reaction electrode are at least partially double-stranded; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, and the oxygen evolution reaction electrode.

[0130] Figure 16 One or more embodiments of an iron-air battery 1600 having a spiral configuration are shown. The iron-air battery 1600 includes an iron electrode 502 in contact with an anode current collector 501, wherein the iron electrode 502 and the anode current collector 501 are arranged in a spiral configuration. The iron-air battery 1600 further includes an ORR electrode 504 having a first surface facing the axis of rotation of the spiral configuration and a second surface opposite thereto in contact with air. In the iron-air battery 1600, an OER electrode 506 is arranged in a spiral configuration and interleaved with the iron electrode 502, wherein the iron electrode 502 and the OER electrode 506 are at least partially double-stranded.

[0131] In Figure 16 , the iron-air battery 1600 further includes an electrolyte (not shown) in contact with the iron electrode 502, the first surface of the ORR electrode 504, and the OER electrode 506. The electrolyte is as described herein.

[0132] In some embodiments, the iron-air battery 1600 may further include a spacer (not shown) disposed between at least a portion of the iron electrode 502 and the OER electrode 506. For example, the spacer may be disposed between the double-stranded portions of the iron electrode 502 and the OER electrode 506. The spacer material may be as described herein.

[0133] In some embodiments, as Figure 16 shown, the iron-air battery 1600 may further include a second ORR electrode 505 having a first surface facing the axis of rotation of the spiral configuration and a second surface opposite thereto in contact with air, wherein the plane of the second ORR electrode 505 is parallel to the plane of the (first) ORR electrode 504.

[0134] According to another aspect, an iron-air battery is provided, including: an iron electrode in contact with an anode current collector, wherein the iron electrode and the anode current collector are arranged in a corrugated structure; and wherein the iron electrode includes a plurality of channels between the corrugations; an oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air; an oxygen evolution reaction electrode interleaved with the plurality of channels of the iron electrode, wherein at least a portion of the oxygen evolution reaction electrode is disposed within the plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode; and wherein the oxygen evolution reaction electrode is arranged in a corrugated structure; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode.

[0135] Figure 17 One or more embodiments of an iron-air battery 1700 having a corrugated structure are shown. The iron-air battery 1700 includes an iron electrode 602 that is in contact with an anode current collector 601, wherein the iron electrode 602 and the anode current collector 601 are arranged in a corrugated structure, as Figure 17 shown therein. The corrugated structure provides a plurality of channels 620 that are disposed between the corrugations or folds / turns of the electrode assembly.

[0136] The iron-air battery 1700 includes an ORR electrode 604 having a first surface facing the plurality of channels 620 and an opposite second surface in contact with air. In some embodiments, the iron-air battery 1700 may further include a second ORR electrode 605 having a first surface facing the plurality of channels 620 and an opposite second surface in contact with air.

[0137] The iron-air battery 1700 includes an OER electrode 606 that is interleaved with the plurality of channels 620 of the iron electrode 602, wherein at least a portion of the OER electrode 606 is disposed within the plurality of channels 620 in a direction perpendicular to the plane of the ORR electrode 604, and wherein the OER electrode 606 is arranged in a corrugated structure. In other words, the iron electrode 602, the current collector 601, and the OER electrode 606 are all arranged in a corrugated structure such that the OER electrode 606 is disposed within the plurality of channels 620 of the iron electrode 602 via the corrugations.

[0138] In Figure 17 the iron-air battery 1700 further includes an electrolyte (not shown) in contact with the iron electrode 602, the first surface of the ORR electrode 604, and the OER electrode 606. The electrolyte is as described herein.

[0139] In some embodiments, the iron-air battery 1700 may further include a spacer (not shown) disposed between at least a portion of the iron electrode 602 and the OER electrode 606, wherein the spacer is arranged in a corrugated configuration. For example, the spacer may be disposed between the corrugated portions of the iron electrode 602 and the OER electrode 606. The spacer material may be as described herein.

[0140] In some embodiments, as Figure 17 shown in, the iron-air battery 1700 may further include a second ORR electrode 605 having a first surface facing a plurality of channels and an opposite second surface in contact with air, wherein the plane of the second ORR electrode 605 is parallel to the plane of the (first) ORR electrode 604.

[0141] In some embodiments, in Figure 17 which, the OER electrode 606 is disposed on the first surface of the iron electrode 602, and the iron-air battery 1700 further includes a second OER electrode (not shown) interleaved with a plurality of channels in the iron electrode 602. The second OER electrode may be disposed at the second opposite surface of the iron electrode 602, wherein at least a portion of the second OER electrode is disposed within the plurality of channels 620 in a direction perpendicular to the plane of the ORR electrode 604, and wherein the second OER electrode is arranged in a corrugated configuration. In some embodiments, the iron electrode may be sandwiched between the first OER electrode and the second OER electrode, wherein the iron electrode, the first OER electrode, and the second OEM electrode are arranged in a corrugated configuration.

[0142] Figures 2 to 17 The components of the iron-air battery described in are interchangeable and will be described below.

[0143] In some embodiments, the electrolyte includes a solid oxide electrolyte, a solid polymer electrolyte, a molten salt, an aqueous solution, a non-aqueous solution, a gel, or a combination thereof. For example, the electrolyte may include an aqueous solution of an alkali metal hydroxide, an organic hydroxide, or a combination thereof.

[0144] The electrolyte may be an aqueous solution. In some embodiments, the electrolyte may be an alkaline solution (pH > 10), a near-neutral solution (10 > pH > 4), or an acidic solution (4 > pH > 0). In some embodiments, the electrolyte may be an alkaline solution having a high hydroxide concentration, such as a hydroxide concentration of or higher than 5 moles per liter (M) (e.g., 5M to 6M, 6M or greater, 6M to 7M, 7M or greater, 7M to 11M, 7M to 10M, 7.5M to 9.5M, greater than 7.5M to less than 9.5M, etc.). In some embodiments, the solvent in the electrolyte may be water, and preferably high-purity water, such as deionized water.

[0145] In various embodiments, the electrolyte may include 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 or a combination thereof. In some embodiments, KOH, NaOH, and / or LiOH may be combined in a ratio of [KOH] > [NaOH] > [LiOH]. For example, some 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]. Still other embodiments may include 4M NaOH, 2M KOH, 0.05M LiOH, or other combinations thereof.

[0146] Various embodiments include using an electrolyte with a high hydroxide concentration, such as a hydroxide concentration of 7M or greater. In various embodiments, an electrolyte with a high hydroxide concentration (such as a hydroxide concentration of 7M or greater) can increase the amount of charge stored in the battery (i.e., the capacity of the battery material), improve the Coulombic efficiency (i.e., increase the fraction of electrons stored in the desired charge product rather than lost in side reactions), and / or reduce the overpotential of the iron-air battery (i.e., increase the voltage).

[0147] The OER electrode may penetrate the electrolyte. For example, the OER electrode may be formed of a porous metal sheet or mesh. In some embodiments, the OER electrode may preferably be formed of a nickel mesh or a nickel-plated steel mesh. The OER electrode may include an oxygen evolution catalyst. For example, in some embodiments, the OER electrode may include a porous metal mesh and an oxygen evolution catalyst.

[0148] Exemplary oxygen evolution catalysts may include nickel, an alloy of nickel and iron, manganese oxide, iron, nickel oxide (NiO x ), nickel hydroxide (NiO x (OH) y ), iron oxide (FeO x ), iron hydroxide (FeO x (OH) y ), etc. The OER electrode is disposed closer to the iron electrode than the ORR electrode to facilitate charging. The OER may be electrically insulated from the iron electrode and the ORR electrode.

[0149] The ORR electrode is conductive and permeable to oxygen. The ORR electrode may include a conductive gas diffusion electrode (GDE) catalyst such as carbon, manganese oxide, silver, platinum, nickel foam, nickel mesh, etc., and may also include a hydrophobic material such as polytetrafluoroethylene (PTFE). For example, the ORR electrode may include a hydrophilic region and a hydrophobic region. The hydrophobic region may be exposed to air, and the hydrophilic region may be exposed to the electrolyte. In other words, the hydrophilic region exposed to the electrolyte is the side facing the multiple channels of the iron electrode.

[0150] The coulombic efficiency of the iron electrode during charging may be affected by the configuration of the OER electrode. For example, the coulombic efficiency can be increased by reducing the distance between the rear of the iron electrode and the OER electrode, thereby reducing the distance that ions must travel through the porous iron electrode to reach iron hydroxide.

[0151] The iron electrode can be a solid, including a dense or porous solid, or a mesh or foam, or a particle or collection of particles, or can be a slurry, ink, suspension or paste. For example, the iron electrode can be a bulk solid. As another example, the iron electrode can be a collection of particles within a suspension, such as small or large particles whose buoyancy is insufficient to cause the suspension to escape into the electrolyte. As another example, the iron electrode can be formed of particles that do not have buoyancy in the electrolyte.

[0152] In some embodiments, the iron electrode can be formed of a porous iron-containing material. For example, the iron electrode can include metallic iron and various iron compounds such as iron oxide, hydroxide, sulfide, carbide, or combinations thereof. In some embodiments, the iron electrode can be formed by granulating, briquetting, pressing, powdering, and / or sintering an iron-containing compound. The iron-containing compound can include one or more forms of iron, from highly reduced (more metallic) iron to highly oxidized iron (with a higher average valence). In some embodiments, the iron electrode can be sintered iron agglomerates having various shapes.

[0153] In some embodiments, atomized or sponge iron powder can be used as a raw material for forming a sintered iron electrode. For example, the iron electrode can include metallurgically bonded sponge iron particles such as direct reduced iron (DRI) or other sponge iron powder particles, wherein the microporosity of the sponge iron particles > 50% by volume, and the particle size of the sponge iron particles > 100 microns.

[0154] In some embodiments, the iron electrode can have a surface density of 1 gram of iron per square centimeter (cm 2 ) to 7 grams of iron per cm 2 relative to the direction perpendicular to the oxygen reduction reaction electrode. For example, the iron electrode can have a surface density of 2 grams of iron per cm 2 to 5 grams of iron per cm 2The surface density. In this document, the average electrode loading may refer to the mass of the iron active material per apparent area, where the apparent area is the area of the plane of the ORR electrode. The difference between the iron active material and the current collector may be that the iron active material is microporous.

[0155] The iron electrode (or multiple anodes including the iron electrode) includes multiple channels. The channels can be vertically oriented to allow the generated bubbles (such as hydrogen bubbles) to move vertically and leave the iron electrode and / or the electrolyte. In other words, the long axis of each channel can extend in the vertical direction. In some embodiments, the channels can have a rectangular cross-section such that the sidewalls of the channels can be disposed in a plane perpendicular or substantially perpendicular to the plane of the ORR electrode. Although shown as uniform channels in the figures, the channels may not all be the same. Some channels can contain an OER electrode, as discussed below. Other channels can be used to provide space for support materials, such as structural reinforcement materials and / or slightly soluble additives, and may not contain an OER electrode, as described herein.

[0156] The multiple channels can be coated with a material that promotes the removal of bubbles from the iron electrode. The channels can also include a structural material that is configured to maintain electrical contact throughout the iron electrode. In some embodiments, the channel width can be less than the width of the protrusions (or features) that define the iron electrode. In some embodiments, due to the multiple channels, the iron electrode can have a channel fraction of about 0.1 to about 0.5 (such as about 0.2 to about 0.45), where the channel fraction is defined as CW / (CW+RW), where CW is the channel width and RW is the rib width (the rib width is the width of the iron electrode feature that defines the channel).

[0157] The multiple channels include an electrolyte. In some embodiments, based on the total volume of the iron electrode when fully charged, the volume fraction of the electrolyte in the iron electrode is 0.5 to 0.9. The electrolyte volume fraction can be defined as (electrolyte volume) / (electrode volume) and can be measured, for example, by mercury porosimetry.

[0158] The current collector can be in the form of a metal plate (such as iron, nickel, stainless steel, nickel-plated stainless steel plate, etc.). The current collector can be porous or non-porous. In some embodiments, the current collector can be a mesh or a perforated sheet with void sizes (e.g., through holes) ranging from about 0.1 mm to about 10 mm to facilitate the flow of the electrolyte.

[0159] The current collector can be configured to electrically connect multiple anodes including the iron anode. In some embodiments, the multiple anodes can be welded to the current collector. In other embodiments, the multiple anodes can optionally be electrically connected by tabs extending from the multiple anodes and formed of iron, steel, or nickel-plated steel. The iron-air battery can also include busbars, wiring, etc. to electrically connect the multiple current collectors to a common electrical terminal.

[0160] The current collector may include branches extending onto or into each rib portion extending from the current collector to the iron electrode, or the iron electrode may be multiple anodes, each anode including a branched current collector disposed therein. For example, the branched current collector may be a highly conductive wire or sheet (e.g., stainless steel) extending within the rib portion or within the multiple anodes. In an alternative, the branched current collector may be in the form of a mesh or cage that surrounds and / or compresses each rib portion or each anode among the multiple anodes.

[0161] The OER electrode may be a planar mesh having a thickness of less than about 1.5 mm or less than about 1.0 mm, such as a nickel mesh or a nickel-plated stainless steel mesh. In some embodiments, the OER electrode may have a thickness of from about 1 mm to about 0.1 mm (such as from about 0.5 mm to about 0.1 mm). The OER electrode may include a catalyst configured to catalyze the oxidation of an alkaline electrolyte material to generate oxygen. When the OER electrode does not form a physical barrier between the iron electrode and the ORR electrode, the OER electrode may be formed of a solid non-mesh material. Any suitable material may be used.

[0162] The OER electrode may include a plurality of cathode protrusions extending from a main body portion into each of a plurality of channels. Thus, the cathode protrusions (or cathodes) may be interleaved with the plurality of channels (or with the plurality of anodes). The main body portion of the OER electrode may electrically connect the cathode protrusions to a charging terminal such that each cathode protrusion (or cathode) receives substantially the same potential during charging.

[0163] The channels may be coated with an inert electrical insulating material that serves to prevent electrical short circuits between the iron electrode and the OER electrode. The channels may include a material for vertically guiding bubbles out of the battery. The channels may also include a structural material for maintaining electrical contact across the iron electrode.

[0164] In some embodiments, one or more additives (including lead, tin, antimony, copper, silver, gold, etc.) may be added to one or more channels of the iron electrode. According to various embodiments, adding one or more additives may improve the charging of the iron-containing negative electrode (iron electrode). In some embodiments, one or more additives may include elements having a low hydrogen evolution reaction rate (HER) in metallic form. In some embodiments, one or more additives may include an electrolyte including one or more hydroxides. In some embodiments, one or more additives may include an electrolyte that does not include hydroxides.

[0165] In various embodiments, an additive that inhibits hydrogen evolution, such as a metal with low hydrogen evolution reaction (HER) activity (such as lead (Pb), tin (Sn), antimony (Sb), etc.), can be added to an electrochemical cell to improve the charging of an iron-based negative electrode (iron anode). In various embodiments, an additive that inhibits hydrogen evolution, such as a metal with low hydrogen evolution reaction (HER) activity (such as lead (Pb), tin (Sn), antimony (Sb), etc.), can be added to the electrolyte and / or anode of an electrochemical cell.

[0166] In some embodiments, an additive that inhibits hydrogen evolution, such as a metal with low hydrogen evolution reaction (HER) activity (such as lead (Pb), tin (Sn), antimony (Sb), etc.), can be added to improve the charging of an iron anode. In some embodiments, an additive that inhibits hydrogen evolution, such as a metal with low hydrogen evolution reaction (HER) activity (such as lead (Pb), tin (Sn), antimony (Sb), etc.), can be added to the electrolyte and / or channels of an iron-air battery.

[0167] In some embodiments, an additive that improves the conductive network in an iron electrode, such as a highly conductive metal (tin (Sn), copper (Cu), silver (Ag), gold (Au)) or its derivatives, can be added to improve the charging of an iron-containing negative electrode. In some embodiments, an additive that improves the conductive network in an iron electrode, such as a highly conductive metal (tin (Sn), copper (Cu), silver (Ag), gold (Au)) or its derivatives, can be added to the electrolyte and / or iron electrode. The highly conductive metal can be a metal element having a resistivity of less than 125 nanoohm meters (nΩ·m).

[0168] In some embodiments, sulfides can be included as an additive in the electrolyte. For example, the electrolyte can have a sulfide concentration between 0.0001 M and 0.5 M, typically sodium sulfide. Other salts can be used to add sulfides to the electrolyte, such as bismuth sulfide, copper sulfide, iron sulfide, manganese sulfide, potassium sulfide, zinc sulfide, etc., or combinations thereof. In some embodiments, no sulfide additive can be added to the electrolyte. In some embodiments, sulfides can be present in other aspects of the electrochemical cell, such as in the form of an additive to the iron electrode. As an example, when there is no sulfide in the electrolyte composition during battery assembly, sulfides or sulfide-containing compounds can be used as an additive to the iron electrode. In some embodiments, other electrolyte additives known in the art for improving the performance of iron electrodes can also be used in the electrolyte.

[0169] The separator can be a passive separator, such as a conventional diaphragm separator, or can be an active separator, such as an ion exchange membrane. In some embodiments, the separator can be selected based on the ability to allow selective transfer of desired molecules or materials while substantially restricting or preventing the transfer of undesired molecules or materials. For example, some separator membranes are ion-selective and allow the transfer of negative (or positive) ions while substantially preventing the transfer of positive (or negative) ions. In other examples, the separator material can be selected based on the ability to allow or prevent bubbles from crossing from one side (associated with one electrode) to the other side (associated with the counter electrode).

[0170] In some embodiments, the separator can be formed of a dielectric material or a porous material that is permeable to positive ions (such as Fe 2+ 、Fe 3+ 、K + 、Na + 、Cs + and / or NH 4 + ions, etc., or combinations thereof) or negative ions, such as hydroxide ions, etc. The separator may be impermeable or effectively impermeable to the active materials of the catholyte and the anolyte. In some embodiments, the separator can be a membrane, such as a membrane formed of a polymer having a tetrafluoroethylene backbone and perfluoro vinyl ether groups side chains terminated with sulfonic acid groups (e.g., sulfonated tetrafluoroethylene membrane, a membrane made of the polymer sold under the Nafion brand, etc.).

[0171] In some embodiments, the separator can include an anion exchange membrane (AEM), a cation exchange membrane (CEM), a zwitterionic membrane, a porous membrane having an average pore size of less than 10 nanometers, a membrane containing polybenzimidazole, a membrane containing polysulfone, a membrane containing polycarboxylic acid, a membrane containing water-containing polyether ketone, a membrane including an inherently microporous (PIM) polymer, etc., or combinations thereof. Preferably, the separator includes an anion exchange membrane (AEM) or a cation exchange membrane (CEM). In some embodiments, the separator can include a composite membrane that includes an inorganic material and an organic material. In some embodiments, the inorganic material can include metal oxides or ceramic materials. In some embodiments, the organic material can include polyetheretherketone (PEEK), polysulfone, polystyrene, polypropylene, polyethylene, etc., or combinations thereof.

[0172] In some embodiments, a separator that provides a physical barrier between the iron electrode and the OER electrode can be used. For example, the separator can include a porous polyolefin film, a glass fiber mat, a cotton fabric, a rayon fabric, cellulose acetate, paper, etc., or combinations thereof. In some embodiments, the separator can be a dielectric structure or frame, a ribbed structure or a porous insulator. In some embodiments, the separator can include a porous frame configured to compress the iron electrode.

[0173] In some embodiments, multiple iron-air batteries (or electrochemical cells) can be electrically connected in series to form a stack. In other embodiments, multiple iron-air batteries (or electrochemical cells) can be electrically connected in parallel. In certain other embodiments, the iron-air batteries (or electrochemical cells) are connected in a combination of series and parallel electrical connections.

[0174] Also provided is a method of preparing an iron-air battery as described herein. The method includes: forming an iron negative electrode material onto an anode current collector to form an iron electrode including a plurality of channels; disposing an oxygen evolution reaction electrode into one or more of the channels of the iron electrode; and assembling an oxygen reduction reaction electrode having a first surface facing the iron electrode and an opposite second surface in contact with air to form an electrode assembly.

[0175] As Figure 18 shown, an iron negative electrode material (e.g., iron powder 700) can be applied to the current collector 740 and then compressed to form the iron electrode, wherein the compression (or forming step) provides a plurality of channels in the iron electrode. For example, an anode powder (such as the iron electrode powder 700) can be disposed on opposite sides of the current collector 740 and fed into a pair of compression rollers 702. The compression rollers 702 can be configured to compress and form channels in the iron powder, thereby forming ribs in the iron anode along the current collector. The compression rollers 702 can be metal rollers having a channel pattern. The compression can occur at room temperature or at an elevated temperature.

[0176] In some embodiments, the iron powder can be poured into a mold having a channel configuration. The iron powder can be compacted within the mold. In some embodiments, the iron powder can be pressed at room temperature and then heated. In some embodiments, the iron powder can be pressed at an elevated temperature. In some embodiments, the iron powder can be compacted in a roll-based continuous process. In some embodiments, the iron powder can be combined with a processing aid and extruded in a continuous process. In some embodiments, the iron powder can be fabricated as a solid planar and then channels are machined therein.

[0177] In some embodiments, the iron powder can be compacted into a planar strip or other shapes (e.g., pyramid, oval, cylindrical, etc.). Then, the strip can be welded to a ridge connected to the current collector. Alternatively, the strip can be directly connected to the current collector without a ridge. Alternatively, each strip can be wrapped in a perforated / mesh steel cage. The cage provides both current collection and compression. The cage can be curled, welded, bolted, etc., or a combination thereof.

[0178] The product output from the compression rollers 702 can be picked up by a conveyor belt 704 and provided to a cutting device 706. The cutting device 706 can separate the product into individual iron electrodes 710. In some embodiments, the cutting device 706 can be configured to polish the cutting edges of the iron electrodes 710.

[0179] The formed iron electrode 710 including multiple channels can be further sintered, etc. before or after the electrode is cut into appropriate lengths. The iron electrode 710 can optionally be provided to the furnace 708 and sintered. The optionally sintered iron electrodes 710 can be stacked and / or used to construct an iron-air battery. In an alternative, multiple iron electrodes 710 can be stacked and sintered together as a group.

[0180] In some embodiments, two iron electrodes can be fabricated back-to-back on opposite sides of a current collector such that they interlock on the channel sides and can still be pressed between parallel plates and achieve uniform strain by deforming together during compaction.

[0181] In other embodiments, iron electrode strips can be formed by compressing iron electrode powder, and the compressed strips can be welded to the ridges or current collectors. In other embodiments, iron electrode powder can be made into sheets and channels can be machined therein. In an alternative, a sacrificial channel former material can be used to displace iron during assembly or compaction and then removed by dissolution, pyrolysis, etc., leaving channels of a desired shape in the fabricated iron electrode. In other embodiments, iron electrodes can be formed by additive manufacturing (e.g., laser sintering or plasma spraying of powdered active materials) to construct a desired electrode geometry. Two iron electrodes can be fabricated back-to-back such that they interlock on the channel sides and can still be pressed between parallel plates and achieve uniform strain by deforming together during compaction.

[0182] In some embodiments, a sacrificial channel former material can be used to displace iron during assembly or compaction and then removed by dissolution, burning out, etc., leaving channels of a desired shape in the fabricated iron electrode.

[0183] In some embodiments, iron electrodes can be fabricated such that the porosity in the ridge portions and the porosity in the rib portions are of substantially the same volume fraction and the pore diameters are substantially the same (i.e., the powder microstructure is uniform throughout the solid-filled portion of the iron electrode). A channel iron electrode with the same porosity in the ribs and ridges can be achieved by sintering the filled powder, metal injection molding, or any suitable method common in the art for assembling large amounts of powder materials and uniformly thermally or mechanically bonding them together. In some cases, a gel powder mass can be coated into shape, dried, and then machined. In some embodiments, the bonding of the powder can be carried out by electrochemical sintering rather than by mechanically driven and / or thermally driven consolidation.

[0184] In some embodiments, the iron electrode may have non-uniform porosity. The ridge portion may play a unique structural role in the anode assembly. The bonding of the material in the ridge portion to the current collector may facilitate the adhesion of the anode to its current collector. Additionally, the ridge portion is thinner than the rib portion, and thus the need to achieve high ion transport in the ridge portion is not as great as in the rest of the iron electrode. Without wishing to be bound by theory, the ridge portion may require a higher degree of compaction and / or a lower porosity relative to the rib portion. The porosity / compaction gradient may be continuous or approximate a discrete step function gradient. The gradient of the porosity may be determined by the manufacturing method employed. For example, roll pressing of a pelletized structure results in a low-density rib structure and a high-density ridge structure.

[0185] In some embodiments, such as Figure 14 the serpentine OER electrode shown in Figure 4 or Figure 5 or Figure 7 and Figure 10 the corrugated OER electrode shown in may be formed by bending, stamping, roll forming, and / or pleating a sheet of wire mesh to match the dimensions of the corresponding iron electrode. In an alternative, the branched electrode portions may be welded to the planar backbone portion of the OER electrode to form an interdigitated OER electrode. As an example, the wire mesh of the OER electrode may include woven mesh, expanded metal, metal foam, etc., or a combination thereof. In some embodiments, alternative fabrication of the OER electrode may include non-continuous OER. For example, the OER electrode may be prepared by welding "branches" (suitable for the anode channels) to a backing backbone portion, as described herein. In various embodiments, the OER electrode may have a catalyst applied before or after forming the OER electrode shape.

[0186] The oxygen evolution catalyst may be applied to the OER electrode before or after forming / welding. A porous dielectric material may be coated / sprayed on the OER electrode to form a spacer. In an alternative, a porous dielectric spacer may be disposed between the iron electrode and the corresponding OER electrode.

[0187] The iron electrode and the OER electrode may be assembled such that a portion of the OER electrode is disposed within the channel. The ORR electrode may be assembled adjacent to the OER electrode to form an electrode assembly. The electrode assembly may be immersed in an electrolyte such that one side of the iron electrode, the OER electrode, and the ORR electrode is in contact with the electrolyte.

[0188] The method further includes: assembling an ORR electrode having a first surface facing the iron electrode and an opposite second surface in contact with air to form an electrode assembly.

[0189] The method may further include: adding an electrolyte to the completed electrode assembly. Alternatively, when the electrolyte is not a liquid, a solid or gel electrolyte may be added to the iron-air battery at any suitable step in the manufacturing process.

[0190] In some embodiments, the separator and / or the support may be designed to facilitate bubble expulsion and prevent electrical short circuits between the iron electrode and the OER cathode. The separator and / or the support may be placed on the planar OER electrode, and then the separator and / or the support and the OER electrode may be bent or corrugated to form a desired shape. Alternatively, after the OER electrode is bent / corrugated, the separator and / or the support may be applied to the OER electrode. In some embodiments, the separator and / or the support may be applied (placed, molded, sprayed, etc.) onto the iron electrode to form a separator-node assembly. The distance between the iron electrode and the OER electrode may be configured to be large enough to allow bubbles to escape, prevent electrical short circuits, and contain the electrolyte without unduly increasing the ionic resistance. For example, in various embodiments, the distance between the iron electrode and the OER electrode may be from 0.1 mm to 5 mm, such as from 1 mm to 4 mm, but the embodiments are not limited thereto.

[0191] To prepare a sample in a charged state for performing mercury porosimetry measurements, the iron electrode may be brought to a fully charged state by charging the battery (i.e., the battery including the iron electrode and the OER electrode) at a current greater than 6 mA / g to at least twice the battery's rated capacity.

[0192] In some embodiments, the iron-air battery may be used in devices, systems, and methods for long-duration and ultra-long-duration, low-cost energy storage. As used herein, "long-duration" and / or "ultra-long-duration" may refer to an energy storage period of 8 hours or longer, such as an energy storage period of 8 hours, an energy storage period of 8 hours to 20 hours, an energy storage period of 20 hours, an energy storage period of 20 hours to 24 hours, an energy storage period of 24 hours, an energy storage period of 24 hours to one week, an energy storage period of one week to one year (e.g., from several days to several weeks to several months), etc. For example, a "long-duration" and / or "ultra-long-duration" iron-air battery may refer to an iron-air battery that may be configured to store energy over a time span of several days, weeks, or seasons. In some embodiments, the iron-air battery may be configured to store energy generated by a solar cell during the summer months when sunlight is abundant and solar power generation exceeds grid requirements, and release the stored energy during the winter months when sunlight may be insufficient to meet grid requirements.

[0193] In some embodiments, the iron-air battery can be incorporated into devices, systems, and methods for energy storage for shorter durations of less than about 8 hours. For example, the iron-air battery can be configured to store energy generated by a solar cell during a day cycle, where solar power generation at noon may exceed the grid requirements and release the stored energy during evening hours when sunlight may be insufficient to meet the grid requirements. As another example, an iron-air battery system can include an energy storage device that serves as a backup power source when the power supplied by the grid is insufficient, for facilities including homes, commercial buildings, factories, hospitals, or data centers, etc., where the required discharge duration may vary from a few minutes to several days.

[0194] The present disclosure is further illustrated by the following examples, which are non-limiting.

[0195] Examples

[0196] The following results were modeled using the battery module of COMSOL software. The iron electrode ribs were considered as porous electrode domains, and electron transport in iron, ion diffusion, and migration in the electrolyte were calculated according to Ohm's law, as well as the Butler-Volmer kinetics for the iron and hydrogen reactions. The volume fraction of iron hydroxide increases during discharge, resulting in a corresponding decrease in the volume fractions of iron and electrolyte, and vice versa during charging.

[0197] The instantaneous Coulombic efficiency is defined as (iron reaction rate) / (iron reaction rate + hydrogen reaction rate). The resistance is defined as (OCV - V) / I, where OCV is the open-circuit voltage, V is the load voltage, and I is the current per apparent area. OCV and V are measured relative to a reference electrode in the separator. The interdigitated and channel configurations have the same areal loading of 4 g Fe / cm 2 as the planar configuration; thus, due to the channels occupying some space, the interdigitated and channel configurations have thicker iron electrodes than the planar configuration. Charging was simulated at 6 mA / g_Fe, while discharging was simulated at 3 mA / g_Fe. The initial porosity of the ribs was set to 0.6. The electrolyte was 6M KOH at 303K. In this document, w_rib can be defined as half of the rib width, i.e., 0.5*RW. In the channel simulation and the interdigitated simulation, the channel fraction was 0.4, and w_rib was 5 mm.

[0198] Figure 19 and Figure 20 are graphs respectively showing the simulated instantaneous Coulombic charge efficiency and discharge resistance for an iron-air battery including planar iron and a charging positive electrode, channel iron electrodes and a planar charging positive electrode, or channel iron electrodes and an interdigitated charging positive electrode.

[0199] Figure 19It shows that the planar geometry is projected to have a low Coulomb efficiency, specifically at the end of charging. The charge reaction converts iron hydroxide to iron metal. At the start of charging, the reaction mainly occurs near the front of the electrode. When the iron hydroxide at the front is consumed, the reaction must shift to the rear of the electrode to obtain more iron hydroxide. However, the reactant for hydrogen evolution is water. Water can flow into the electrode to replenish the consumed water. Thus, hydrogen evolution can continue at the front of the electrode. There is a higher resistance to the reaction at the rear of the electrode because the ions in the electrolyte have to travel further to reach the rear of the electrode. The reaction will be distributed in a way that minimizes the overall cell resistance. If the resistance to consuming iron hydroxide at the rear of the electrode is higher than the resistance to hydrogen evolution at the front of the electrode, the reaction will preferentially shift to hydrogen evolution. The front of the electrode is the side closest to the counter electrode.

[0200] It is calculated that the channel design can moderately improve the Coulomb efficiency because the channel provides a lower resistance path for the ions to travel to the rear of the electrode. It is predicted that the staggered interdigitated design will significantly improve the Coulomb efficiency because the staggered interdigitated geometry significantly reduces the ion path length over the entire region from the charging positive electrode to the iron electrode.

[0201] Figure 20 It shows that since the two designs have the same geometry for the discharging positive electrode, it is predicted that the resistance during discharging is the same for the channel geometry and the staggered interdigitated geometry. At the start of discharging, the iron metal at the front of the iron electrode reacts to form iron hydroxide. When the iron becomes covered with iron hydroxide, the reaction shifts to the rear of the electrode. Since the ions in the electrolyte have to travel further to reach the rear of the electrode, the potential drop in the solution is greater, and thus the resistance during discharging increases over time. The resistance of the channel iron electrode at the end of discharging is lower than that of the planar iron electrode because the channel provides a lower resistance path for ion transport to the rear of the iron electrode.

[0202] Figure 21 It is a graph showing the simulated Coulomb efficiency of channel cells and staggered interdigitated cells with different rib widths. Figure 22 It is a graph showing the simulated discharging resistance during discharging of channel cells and staggered interdigitated cells with different rib widths. In the simulation, the channel fraction is 0.4, and the load is 4 g Fe / cm 2 .

[0203] Reference Figure 21 and Figure 22, The coulombic efficiency of the simulated predictive channel battery is not very sensitive to the rib width because it is more dominated by the gradient in the through-plane direction. Staggering the charging positive electrodes eliminates the through-plane gradient during charging, thus increasing the coulombic efficiency until we can see its sensitivity to the rib width. The resistance increases with time because the ions in the electrolyte must travel further through the iron electrode to reach the iron reactant. The greater travel distance results in a steeper slope of the resistance relative to the charge passed.

[0204] Figure 23 is a graph showing the predicted coulombic efficiency of the channel battery and the staggered interdigitated battery with different areal loadings. For the iron electrode, a higher loading means a thicker electrode at the same density. Figure 24 is a graph showing the predicted areal specific resistance during discharge of the staggered interdigitated battery with different areal loadings. Refer to Figure 23 and Figure 24 , The coulombic efficiency of the channel electrode is a strong function of the areal loading because a thicker electrode means the ions must travel further to reach the reactant. Since the path from the OER electrode to the iron reactant is perpendicular to the electrode thickness direction, the coulombic efficiency of the staggered interdigitated electrode is completely independent of the loading.

[0205] Figure 25 is a graph showing the predicted effect of the channel fraction on the performance of the channel iron electrode. Figure 26 is a graph showing the simulated negative electrode resistance during discharge. Refer to Figure 25 and Figure 26 , ChanFrac = CW / (CW + RW). ChanFrac is the porosity introduced by the channel. In the staggered interdigitated design, the channel must be wide enough to accommodate the charging positive electrode and optionally the separator. For a w_rib of about 5 mm, this limits the channel fraction to at least 0.4. Since a wider channel introduces the cost of additional electrolyte and additional packaging (housing) material, cost considerations may lead to the selection of a narrower channel section.

[0206] This channel is used to provide a low tortuosity path for electrolyte transport. Therefore, the rib can have a lower porosity compared to the case where there is no channel in the iron electrode. A low porosity in the rib can promote particle-to-particle contact.

[0207] Figure 27 is a graph with representative experimental data showing the discharge voltage as a function of the capacity collected from two iron-air battery cells. Both cells contain an iron negative electrode, an ORR discharge positive electrode, and an OER charging positive electrode. The cell labeled "planar" is constructed similar to the control cell shown in Figure 1 The cell labeled "staggered interdigitated" is the one with the same as Figure 15An experimental cell with a staggered interdigitated OER electrode configuration similar to that shown. Except for the configurations of the iron electrode and the OER electrode, all experimental parameters were kept constant across the two cells, including the iron electrode surface density, temperature, charge and discharge current, electrolyte composition, and the ORR electrode composition and geometry. As the discharge capacity increased, the experimental cell with the channel iron electrode and the staggered interdigitated configuration showed an extended upper voltage plateau compared to the planar control cell. This result is consistent with Figure 20 the COMSOL simulations shown therein. The extended discharge voltage plateau in the iron electrode with channels indicates a reduced increase in resistance during the discharge process compared to the planar control cell. This results in an increased average discharge voltage and an increased energy storage capacity for the experimental staggered interdigitated cell compared to the planar control cell.

[0208] The present disclosure also encompasses the following embodiments.

[0209] Aspect 1. An iron-air battery, comprising: an iron electrode in contact with an anode current collector, wherein the iron electrode includes a plurality of channels; an oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air; an oxygen evolution reaction electrode interdigitated with the plurality of channels of the iron electrode, wherein at least a portion of the oxygen evolution reaction electrode is disposed within the plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode.

[0210] Aspect 2. The iron-air battery according to aspect 1, further comprising a spacer disposed between at least a portion of the iron electrode and the oxygen evolution reaction electrode.

[0211] Aspect 3. The iron-air battery according to aspect 1 or 2, wherein the oxygen evolution reaction electrode includes: a plurality of cathode protrusions disposed within the plurality of channels; and a backbone portion connected to the plurality of cathode protrusions, wherein the backbone portion is not interdigitated with the plurality of channels of the iron electrode, and wherein the backbone portion is disposed between the iron electrode and the oxygen reduction reaction electrode.

[0212] Aspect 4. The iron-air battery according to aspect 3, wherein one or more of the plurality of cathode protrusions have an average length of 3 mm to 50 mm when measured from the backbone portion.

[0213] Aspect 5. The iron-air battery according to any one of aspects 1 to 4, wherein more than 25% of the plurality of channels include an oxygen evolution reaction electrode disposed therein.

[0214] Aspect 6. The iron-air battery according to any one of aspects 1 to 5, wherein one or more of the plurality of channels further include an additive.

[0215] Aspect 7. The iron-air battery according to any one of Aspects 1 to 6, wherein one or more of the plurality of channels have an average length of 3 mm to 50 mm in a direction perpendicular to the plane of the oxygen reduction reaction electrode and an average width of 1 mm to 40 mm in a direction parallel to the plane of the oxygen reduction reaction electrode.

[0216] Aspect 8. The iron-air battery according to any one of Aspects 1 to 7, wherein one or more of the plurality of channels have an average width of 1 mm to 40 mm in a direction parallel to the plane of the oxygen reduction reaction electrode.

[0217] Aspect 9. The iron-air battery according to any one of Aspects 1 to 8, wherein when measured between the centers of adjacent channels, one or more of the plurality of channels are spaced apart from each other by an average distance of 10 mm to 50 mm in a direction parallel to the plane of the oxygen reduction reaction electrode.

[0218] Aspect 10. The iron-air battery according to any one of Aspects 1 to 9, wherein each of the plurality of channels independently has a rectangular prism shape, a cylindrical shape, a pyramid shape, or a trapezoidal prism shape.

[0219] Aspect 11. The iron-air battery according to any one of Aspects 1 to 10, wherein the oxygen evolution reaction electrode includes a porous metal mesh and an oxygen evolution catalyst.

[0220] Aspect 12. The iron-air battery according to any one of Aspects 1 to 11, wherein the oxygen evolution reaction electrode is arranged in a corrugated structure within the plurality of channels.

[0221] Aspect 13. The iron-air battery according to any one of Aspects 1 to 12, wherein the anode current collector includes: one or more branch current collectors arranged parallel to the plurality of channels; and a main current collector connected to the one or more branch current collectors, wherein the main current collector is arranged parallel to the first surface of the oxygen reduction reaction electrode.

[0222] Aspect 14. The iron-air battery according to any one of Aspects 1 to 13, wherein the electrolyte includes a solid oxide electrolyte, a solid polymer electrolyte, a molten salt, an aqueous solution, a non-aqueous solution, a gel, or a combination thereof.

[0223] Aspect 15. The iron-air battery according to any one of Aspects 1 to 14, wherein the electrolyte includes an aqueous solution of an alkali metal hydroxide, an organic hydroxide, or a combination thereof.

[0224] Aspect 16. The iron-air battery according to any one of Aspects 1 to 15, wherein the iron electrode has a surface density of 1 g of iron per square centimeter to 7 g of iron per square centimeter with respect to a direction perpendicular to the oxygen reduction reaction electrode.

[0225] Aspect 17. The iron-air battery according to any one of Aspects 1 to 16, wherein, based on the total volume of the iron electrode when fully charged, the volume fraction of the electrolyte in the iron electrode is 0.5 to 0.9.

[0226] Aspect 18. The iron-air battery according to any one of Aspects 1 to 17, wherein the anode current collector includes a first surface and an opposite second surface, the iron electrode includes a first iron electrode located on the first surface of the first current collector and a second iron electrode located on the second surface of the first current collector, wherein the first iron electrode includes a first plurality of channels, and the second iron electrode includes a second plurality of channels; the oxygen reduction reaction electrode has a first surface facing the first plurality of channels and an opposite second surface in contact with air; the oxygen evolution reaction electrode is interleaved with the first plurality of channels of the first iron electrode, wherein at least a part of the oxygen evolution reaction electrode is disposed in the first plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode; the first electrolyte is in contact with the first iron electrode, the first surface of the oxygen reduction reaction electrode, the first plurality of channels, and the oxygen evolution reaction electrode; and wherein the iron-air battery further includes: a second oxygen reduction reaction electrode having a first surface facing the second plurality of channels and an opposite second surface in contact with air; a second oxygen evolution reaction electrode interleaved with the second plurality of channels of the second iron electrode, wherein at least a part of the second oxygen evolution reaction electrode is disposed in the second plurality of channels in a direction perpendicular to the plane of the second oxygen reduction reaction electrode; and a second electrolyte in contact with the second iron electrode, the first surface of the oxygen reduction reaction electrode, the second plurality of channels, and the second oxygen evolution reaction electrode, wherein the electrolyte and the second electrolyte are the same or different.

[0227] Aspect 19. The iron-air battery according to any one of Aspects 1 to 17, further including: a second iron electrode in contact with a second anode current collector, wherein the second iron electrode includes a second plurality of channels; a second oxygen reduction reaction electrode having a first surface facing the second plurality of channels and an opposite second surface in contact with air; a second oxygen evolution reaction electrode interleaved with the second plurality of channels of the second iron electrode, wherein at least a part of the second oxygen evolution reaction electrode is disposed in the second plurality of channels in a direction perpendicular to the plane of the second oxygen reduction reaction electrode; a second electrolyte in contact with the second iron electrode, the first surface of the second oxygen reduction reaction electrode, the second plurality of channels, and the second oxygen evolution reaction electrode; and an air channel disposed between the second surface of the oxygen reduction reaction electrode and the second surface of the second oxygen reduction reaction, wherein the electrolyte and the second electrolyte are the same or different.

[0228] Aspect 20. An iron-air battery, comprising: an iron electrode including a plurality of anodes separated by a plurality of channels, wherein the plurality of anodes are electrically connected to each other; an oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air; an oxygen evolution reaction electrode interleaved with the plurality of channels, wherein at least a part of the oxygen evolution reaction electrode is disposed in the plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode.

[0229] Aspect 21. The iron-air battery according to Aspect 20, wherein each of the plurality of anodes is in contact with an anode current collector.

[0230] Aspect 22. The iron-air battery according to Aspect 20 or 21, further comprising a spacer disposed between at least a part of the iron electrode and the oxygen evolution reaction electrode.

[0231] Aspect 23. The iron-air battery according to any one of Aspects 20 to 22, wherein the oxygen evolution reaction electrode includes: a plurality of cathode protrusions disposed in the plurality of channels; and a main body portion connected to the plurality of cathode protrusions, wherein the main body portion is not interleaved with the plurality of channels of the iron electrode, and wherein the main body portion is disposed between the iron electrode and the oxygen reduction reaction electrode.

[0232] Aspect 24. The iron-air battery according to any one of Aspects 20 to 23, wherein one or more of the plurality of cathode protrusions have an average length of 3 mm to 50 mm when measured from the main body portion.

[0233] Aspect 25. The iron-air battery according to any one of Aspects 20 to 24, wherein more than 25% of the plurality of channels include the oxygen evolution reaction electrode disposed therein.

[0234] Aspect 26. The iron-air battery according to any one of Aspects 20 to 25, wherein one or more of the plurality of channels further include an additive.

[0235] Aspect 27. The iron-air battery according to any one of Aspects 20 to 26, wherein one or more of the plurality of anodes have an average length of 3 mm to 50 mm in a direction perpendicular to the plane of the oxygen reduction reaction electrode and an average width of 1 mm to 40 mm in a direction parallel to the plane of the oxygen reduction reaction electrode.

[0236] Aspect 28. The iron-air battery according to any one of Aspects 20 to 27, wherein two or more of the plurality of anodes are spaced apart from each other by an average distance of 10 mm to 50 mm in a direction parallel to the plane of the oxygen reduction reaction electrode.

[0237] Aspect 29. The iron-air battery according to any one of Aspects 20 to 28, wherein the oxygen evolution reaction electrode comprises a porous metal mesh and an oxygen evolution catalyst.

[0238] Aspect 30. The iron-air battery according to any one of Aspects 20 to 29, wherein each of the plurality of anodes is in contact with a branch current collector, and each branch current collector is connected to a main current collector disposed parallel to the first surface of the oxygen reduction reaction electrode.

[0239] Aspect 31. The iron-air battery according to any one of Aspects 20 to 30, wherein each of the plurality of anodes is in contact with a branch current collector, and each branch current collector is connected to a main current collector disposed parallel to the first surface of the oxygen reduction reaction electrode, and the main current collector is disposed outside the plane defining the active regions of the iron electrode, the oxygen evolution reaction electrode, and the oxygen reduction reaction electrode.

[0240] Aspect 32. The iron-air battery according to any one of Aspects 20 to 31, wherein the oxygen evolution reaction electrode is disposed in a plurality of channels between the plurality of anodes in a serpentine configuration.

[0241] Aspect 33. The iron-air battery according to any one of Aspects 20 to 32, further comprising a second oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air, wherein the plane of the second oxygen reduction reaction electrode is parallel to the plane of the oxygen reduction reaction electrode.

[0242] Aspect 34. The iron-air battery according to any one of Aspects 20 to 33, wherein the electrolyte comprises a solid oxide electrolyte, a solid polymer electrolyte, a molten salt, an aqueous solution, a non-aqueous solution, a gel, or a combination thereof.

[0243] Aspect 35. The iron-air battery according to any one of Aspects 20 to 34, wherein the electrolyte comprises an aqueous solution of an alkali metal hydroxide, an organic hydroxide, or a combination thereof.

[0244] Aspect 36. The iron-air battery according to any one of Aspects 20 to 35, wherein each anode of the iron electrode has a surface density of 1 g / cm² to 7 g / cm² of iron relative to a direction perpendicular to the oxygen reduction reaction electrode.

[0245] Aspect 37. The iron-air battery according to any one of Aspects 20 to 36, wherein, based on the total volume of the iron electrode at full charge, the volume fraction of the electrolyte in the iron electrode is 0.5 to 0.9.

[0246] Aspect 38. An iron-air battery, comprising: an iron electrode including a plurality of anodes separated by a plurality of channels, wherein the plurality of anodes are electrically connected to each other; an oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air; an oxygen evolution reaction electrode including a plurality of cathodes interleaved with the plurality of anodes, wherein the plurality of cathodes are disposed in the plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode, and wherein the plurality of cathodes are electrically connected to each other; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode.

[0247] Aspect 39. The iron-air battery according to Aspect 38, wherein each of the plurality of anodes is in contact with an anode current collector.

[0248] Aspect 40. The iron-air battery according to Aspect 38 or 39, further comprising a spacer disposed between at least a portion of the plurality of anodes and the plurality of cathodes.

[0249] Aspect 41. The iron-air battery according to any one of Aspects 38 to 40, wherein one or more of the plurality of cathodes have an average length of 3 mm to 50 mm when measured in a direction perpendicular to the plane of the oxygen reduction reaction electrode.

[0250] Aspect 42. The iron-air battery according to any one of Aspects 38 to 41, wherein more than 25% of the plurality of channels include an oxygen evolution reaction electrode disposed therein.

[0251] Aspect 43. The iron-air battery according to any one of Aspects 38 to 42, wherein one or more of the plurality of channels further include an additive.

[0252] Aspect 44. The iron-air battery according to any one of Aspects 38 to 43, wherein one or more of the plurality of anodes have an average length of 3 mm to 50 mm in a direction perpendicular to the plane of the oxygen reduction reaction electrode and an average width of 1 mm to 40 mm in a direction parallel to the plane of the oxygen reduction reaction electrode.

[0253] Aspect 45. The iron-air battery according to any one of Aspects 38 to 44, wherein two or more of the plurality of anodes are spaced apart from each other by an average distance of 10 mm to 50 mm in a direction parallel to the plane of the oxygen reduction reaction electrode.

[0254] Aspect 46. The iron-air battery according to any one of Aspects 38 to 45, wherein each of the plurality of anodes is in contact with a branched current collector, and wherein each branched current collector is connected to a main current collector disposed parallel to the first surface of the oxygen reduction reaction electrode.

[0255] Aspect 47. The iron-air battery according to any one of aspects 38 to 46, wherein each of the plurality of anodes is in contact with a branched current collector, and each branched current collector is connected to a main current collector disposed parallel to the first surface of the oxygen reduction reaction electrode, and the main current collector is disposed outside the plane defining the active regions of the iron electrode, the oxygen evolution reaction electrode, and the oxygen reduction reaction electrode.

[0256] Aspect 48. The iron-air battery according to any one of aspects 38 to 47, wherein each of the plurality of cathodes is in contact with a cathode current collector, and the cathode current collector is disposed outside the plane defining the active regions of the iron electrode, the oxygen evolution reaction electrode, and the oxygen reduction reaction electrode.

[0257] Aspect 49. The iron-air battery according to any one of aspects 38 to 48, further comprising a second oxygen reduction reaction electrode having a first surface facing the plurality of channels and a second opposite surface in contact with air, wherein the plane of the second oxygen reduction reaction electrode is parallel to the plane of the oxygen reduction reaction electrode.

[0258] Aspect 50. The iron-air battery according to any one of aspects 38 to 49, wherein the electrolyte comprises a solid oxide electrolyte, a solid polymer electrolyte, a molten salt, an aqueous solution, a non-aqueous solution, a gel, or a combination thereof.

[0259] Aspect 51. The iron-air battery according to any one of aspects 38 to 50, wherein the electrolyte comprises an aqueous solution of an alkali metal hydroxide, an organic hydroxide, or a combination thereof.

[0260] Aspect 52. The iron-air battery according to any one of aspects 38 to 51, wherein each anode of the iron electrode has a surface density of 1 g / cm² to 7 g / cm² of iron relative to the direction perpendicular to the oxygen reduction reaction electrode.

[0261] Aspect 53. The iron-air battery according to any one of aspects 38 to 52, wherein based on the total volume of the iron electrode at full charge, the volume fraction of the electrolyte in the iron electrode is 0.5 to 0.9.

[0262] Aspect 54. The iron-air battery according to any one of aspects 38 to 53, wherein each of the plurality of cathodes comprises an oxygen evolution catalyst.

[0263] Aspect 55. An iron-air battery, comprising: an iron electrode in contact with an anode current collector, wherein the iron electrode includes a plurality of channels; an oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air; an oxygen evolution reaction electrode including a plurality of cathodes interleaved with the iron electrode, wherein the plurality of cathodes are disposed within the plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode, and wherein the plurality of cathodes are electrically connected to each other; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode.

[0264] Aspect 56. The iron-air battery according to aspect 55, further comprising a spacer disposed between at least a portion of the iron electrode and the plurality of cathodes.

[0265] Aspect 57. The iron-air battery according to aspect 55 or 56, wherein one or more of the plurality of cathodes have an average length of 3 mm to 50 mm when measured in a direction perpendicular to the plane of the oxygen reduction reaction electrode.

[0266] Aspect 58. The iron-air battery according to any one of aspects 55 to 57, wherein more than 25% of the plurality of channels include cathodes among the plurality of cathodes disposed therein.

[0267] Aspect 59. The iron-air battery according to any one of aspects 55 to 58, wherein one or more of the plurality of channels further include an additive.

[0268] Aspect 60. The iron-air battery according to any one of aspects 55 to 59, wherein one or more of the plurality of channels have an average length of 3 mm to 50 mm in a direction perpendicular to the plane of the oxygen reduction reaction electrode and an average width of 1 mm to 40 mm in a direction parallel to the plane of the oxygen reduction reaction electrode.

[0269] Aspect 61. The iron-air battery according to any one of aspects 55 to 60, wherein one or more of the plurality of channels have an average width of 1 mm to 40 mm in a direction parallel to the plane of the oxygen reduction reaction electrode, wherein a first width closest to the oxygen reduction reaction electrode is 1% to 500% greater than a second width farther from the oxygen reduction reaction electrode.

[0270] Aspect 62. The iron-air battery according to any one of aspects 55 to 61, wherein one or more of the plurality of channels are spaced apart from each other by an average distance of 10 mm to 50 mm in a direction parallel to the plane of the oxygen reduction reaction electrode when measured between the centers of adjacent channels.

[0271] Aspect 63. The iron-air battery according to any one of aspects 55 to 62, wherein each of the plurality of channels independently has a rectangular prism shape, a cylindrical shape, a pyramid shape, or a trapezoidal prism shape.

[0272] Aspect 64. The iron-air battery according to any one of aspects 55 to 63, wherein each of the plurality of cathodes is in contact with a cathode current collector, and the cathode current collector is disposed outside the plane defining the active regions of the iron electrode, the oxygen evolution reaction electrode, and the oxygen reduction reaction electrode.

[0273] Aspect 65. The iron-air battery according to any one of aspects 50 to 64, wherein the anode current collector includes: one or more branch current collectors disposed parallel to the plurality of channels; and a main current collector connected to the one or more branch current collectors, wherein the main current collector is disposed parallel to the first surface of the oxygen reduction reaction electrode.

[0274] Aspect 66. The iron-air battery according to any one of aspects 50 to 65, wherein the electrolyte includes a solid oxide electrolyte, a solid polymer electrolyte, a molten salt, an aqueous solution, a non-aqueous solution, a gel, or a combination thereof.

[0275] Aspect 67. The iron-air battery according to any one of aspects 55 to 66, wherein the electrolyte includes an aqueous solution of an alkali metal hydroxide, an organic hydroxide, or a combination thereof.

[0276] Aspect 68. The iron-air battery according to any one of aspects 55 to 67, wherein the iron electrode has a surface density of 1 g of iron / cm² to 7 g of iron / cm² with respect to a direction perpendicular to the oxygen reduction reaction electrode.

[0277] Aspect 69. The iron-air battery according to any one of aspects 55 to 68, wherein, based on the total volume of the iron electrode at full charge, the volume fraction of the electrolyte in the iron electrode is 0.5 to 0.9.

[0278] Aspect 70. There is provided an iron-air battery including: an iron electrode in contact with an anode current collector, wherein the iron electrode and the anode current collector are arranged in a spiral configuration; an oxygen reduction reaction electrode having a first surface facing the axis of rotation of the spiral configuration and an opposite second surface in contact with air; an oxygen evolution reaction electrode arranged in a spiral configuration and interleaved with the iron electrode, wherein the iron electrode and the oxygen evolution reaction electrode are at least partially double-stranded; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, and the oxygen evolution reaction electrode.

[0279] Aspect 71. The iron-air battery according to aspect 70 further includes a spacer disposed between at least a portion of the iron electrode and the oxygen evolution reaction electrode.

[0280] Aspect 72. The iron-air battery according to Aspect 70 or 71 further includes a second oxygen reduction reaction electrode having a first surface facing the axis of rotation of the helical structure and an opposite second surface in contact with air, wherein the plane of the second oxygen reduction reaction electrode is parallel to the plane of the oxygen reduction reaction electrode.

[0281] Aspect 73. The iron-air battery according to any one of Aspects 70 to 72, wherein the electrolyte includes a solid oxide electrolyte, a solid polymer electrolyte, a molten salt, an aqueous solution, a non-aqueous solution, a gel, or a combination thereof.

[0282] Aspect 74. The iron-air battery according to any one of Aspects 70 to 73, wherein the electrolyte includes an aqueous solution of an alkali metal hydroxide, an organic hydroxide, or a combination thereof.

[0283] Aspect 75. The iron-air battery according to any one of Aspects 70 to 74, wherein each anode of the iron electrode has a surface density of 1 g / cm² to 7 g / cm² of iron relative to the direction perpendicular to the oxygen reduction reaction electrode.

[0284] Aspect 76. The iron-air battery according to any one of Aspects 70 to 75, wherein, based on the total volume of the iron electrode when fully charged, the volume fraction of the electrolyte in the iron electrode is 0.5 to 0.9.

[0285] Aspect 77. An iron-air battery includes: an iron electrode in contact with an anode current collector, wherein the iron electrode and the anode current collector are arranged in a corrugated structure; and wherein the iron electrode includes a plurality of channels between the corrugations; an oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air; an oxygen evolution reaction electrode interleaved with the plurality of channels of the iron electrode, wherein at least a portion of the oxygen evolution reaction electrode is disposed within the plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode, and wherein the oxygen evolution reaction electrode is arranged in a corrugated structure; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode.

[0286] Aspect 78. The iron-air battery according to Aspect 77 further includes a spacer disposed between at least a portion of the iron electrode and the oxygen evolution reaction electrode.

[0287] Aspect 79. The iron-air battery according to Aspect 77 or 78, wherein the oxygen evolution reaction electrode includes a porous metal mesh and an oxygen evolution catalyst.

[0288] Aspect 80. The iron-air battery according to any one of aspects 77 to 79, wherein the oxygen evolution reaction electrode is disposed at a first surface of the iron electrode, and further includes a second oxygen evolution reaction electrode that is interleaved with a plurality of channels of the iron electrode, wherein the second oxygen evolution reaction electrode is disposed at a second opposite surface of the iron electrode, wherein at least a part of the second oxygen evolution reaction electrode is disposed within the plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode, and wherein the second oxygen evolution reaction electrode is disposed in a corrugated configuration.

[0289] Aspect 81. The iron-air battery according to any one of aspects 77 to 80, further including a second oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air, wherein the plane of the second oxygen reduction reaction electrode is parallel to the plane of the oxygen reduction reaction electrode.

[0290] Aspect 82. The iron-air battery according to any one of aspects 77 to 81, wherein the electrolyte includes a solid oxide electrolyte, a solid polymer electrolyte, a molten salt, an aqueous solution, a non-aqueous solution, a gel, or a combination thereof.

[0291] Aspect 83. The iron-air battery according to any one of aspects 77 to 82, wherein the electrolyte includes an aqueous solution of an alkali metal hydroxide, an organic hydroxide, or a combination thereof.

[0292] Aspect 84. The iron-air battery according to any one of aspects 77 to 83, wherein each anode of the iron electrode has a surface density of 1 g of iron per square centimeter to 7 g of iron per square centimeter with respect to a direction perpendicular to the oxygen reduction reaction electrode.

[0293] Aspect 85. The iron-air battery according to any one of aspects 77 to 84, wherein, based on the total volume of the iron electrode at full charge, the volume fraction of the electrolyte in the iron electrode is 0.5 to 0.9.

[0294] Aspect 86. A method of forming an iron-air battery according to any one of aspects 1 to 19, the method including: forming an iron negative electrode material onto an anode current collector to form an iron electrode including a plurality of channels; disposing an oxygen evolution reaction electrode into one or more of the channels of the iron electrode; and assembling an oxygen reduction reaction electrode having a first surface facing the iron electrode and an opposite second surface in contact with air to form an electrode assembly.

[0295] Aspect 87. The method according to aspect 86, wherein forming includes: compressing the iron negative electrode material onto the current collector to form a plurality of channels disposed in the iron electrode.

[0296] Aspect 88. The method according to aspect 87, wherein forming further includes: sintering.

[0297] Aspect 89. The method according to any one of aspects 86 to 88 further comprises: adding an electrolyte to the electrode assembly.

[0298] The compositions, methods, and articles may alternatively comprise any suitable materials, steps, or components disclosed herein, consist of any suitable materials, steps, or components disclosed herein, or consist essentially of any suitable materials, steps, or components disclosed herein. The compositions, methods, and articles may additionally or alternatively be formulated to be free or substantially free of any material (or form), step, or component that would otherwise be unnecessary for the function or goal of the composition, method, or article.

[0299] All ranges disclosed herein include the endpoints, and the endpoints can be combined independently of each other (e.g., a range of "up to 25 wt.%, or more specifically, 5 wt.% to 20 wt.%" includes the endpoints and all intermediate values within the range of "5 wt.% to 25 wt.%", etc.). "Combination" includes blends, mixtures, alloys, reaction products, etc. The terms "first", "second", etc. do not denote any order, quantity, or importance, but are used to distinguish one element from another. The terms "a" and "an" and "the" do not denote a quantity limitation, but are to be construed as covering both the singular and the plural, unless otherwise specified herein or clearly contradicted by the context. "Or" means "and / or" unless otherwise expressly stated. Throughout the specification, references to "some embodiments", "an embodiment", etc. mean that a particular element described in connection with that embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. Additionally, it should be understood that the described elements can be combined in any suitable manner in various embodiments. "Its combination" is open-ended and includes any combination, including at least one of the listed components or attributes, and optionally similar or equivalent components or attributes not listed.

[0300] Unless otherwise specified herein, all test standards are the latest standards in effect as of the filing date of this application, or, if priority is claimed, the filing date of the earliest priority application in which the test standard appears.

[0301] Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The entire contents of all cited patents, patent applications, and other references are incorporated herein by reference. However, if a term in this application conflicts or contradicts a term in the incorporated references, the term from this application shall prevail over the conflicting term from the incorporated references.

[0302] Although specific embodiments have been described, alternative, modifications, variations, improvements, and substantial equivalents may be contemplated by the applicant or other persons skilled in the art, which are currently unforeseen or may not have been foreseen at the time of filing. Accordingly, the appended claims, as submitted and as they may be amended, are intended to cover all such alternatives, modifications, variations, improvements, and substantial equivalents.

Claims

1. An iron-air battery, comprising: an iron electrode in contact with an anode current collector, wherein the iron electrode includes a plurality of channels; an oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air; an oxygen evolution reaction electrode interleaved with the plurality of channels of the iron electrode, wherein at least a portion of the oxygen evolution reaction electrode is disposed within the plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode.

2. The iron-air battery according to claim 1, further comprising a spacer disposed between at least a portion of the iron electrode and the oxygen evolution reaction electrode.

3. The iron-air battery according to claim 1 or 2, wherein, the oxygen evolution reaction electrode includes: a plurality of cathode protrusions disposed within the plurality of channels; and a main body portion connected to the plurality of cathode protrusions, wherein the main body portion is not interleaved with the plurality of channels of the iron electrode, and wherein the main body portion is disposed between the iron electrode and the oxygen reduction reaction electrode.

4. The iron-air battery according to claim 3, wherein, one or more of the plurality of cathode protrusions have an average length of 3 mm to 50 mm when measured from the main body portion.

5. The iron-air battery according to any one of claims 1 to 4, wherein, more than 25% of the plurality of channels include an oxygen evolution reaction electrode disposed therein.

6. The iron-air battery according to any one of claims 1 to 5, wherein, one or more of the plurality of channels further include an additive.

7. The iron-air battery according to any one of claims 1 to 6, wherein, one or more of the plurality of channels have an average length of 3 mm to 50 mm in a direction perpendicular to the plane of the oxygen reduction reaction electrode and an average width of 1 mm to 40 mm in a direction parallel to the plane of the oxygen reduction reaction electrode.

8. The iron-air battery according to any one of claims 1 to 7, wherein, one or more of the plurality of channels have an average width of 1 mm to 40 mm in a direction parallel to the plane of the oxygen reduction reaction electrode.

9. The iron-air battery according to any one of claims 1 to 8, wherein, when measured between the centers of adjacent channels, one or more of the plurality of channels are spaced apart from each other by an average distance of 10 mm to 50 mm in a direction parallel to the plane of the oxygen reduction reaction electrode.

10. The iron-air battery according to any one of claims 1 to 9, wherein, each of the plurality of channels independently has a rectangular prism shape, a cylindrical shape, a pyramid shape, or a trapezoidal prism shape.

11. The iron-air battery according to any one of claims 1 to 10, wherein, the oxygen evolution reaction electrode includes a porous metal mesh and an oxygen evolution catalyst.

12. The iron-air battery according to any one of claims 1 to 11, wherein, the oxygen evolution reaction electrode is arranged in the plurality of channels in a corrugated configuration.

13. The iron-air battery according to any one of claims 1 to 12, wherein, the anode current collector includes: one or more branch current collectors arranged parallel to the plurality of channels; and a main current collector connected to the one or more branch current collectors, wherein the main current collector is arranged parallel to the first surface of the oxygen reduction reaction electrode.

14. The iron-air battery according to any one of claims 1 to 13, wherein, the electrolyte includes a solid oxide electrolyte, a solid polymer electrolyte, a molten salt, an aqueous solution, a non-aqueous solution, a gel, or a combination thereof.

15. The iron-air battery according to any one of claims 1 to 14, wherein, the electrolyte includes an aqueous solution of an alkali metal hydroxide, an organic hydroxide, or a combination thereof.

16. The iron-air battery according to any one of claims 1 to 15, wherein, the iron electrode has a surface density of 1 g / cm² to 7 g / cm² of iron relative to the direction perpendicular to the oxygen reduction reaction electrode.

17. The iron-air battery according to any one of claims 1 to 16, wherein, based on the total volume of the iron electrode when fully charged, the volume fraction of the electrolyte in the iron electrode is 0.5 to 0.

9.

18. The iron-air battery according to any one of claims 1 to 17, wherein, the anode current collector includes a first surface and an opposite second surface, the iron electrode includes a first iron electrode located on the first surface of the first current collector and a second iron electrode located on the second surface of the first current collector, wherein the first iron electrode includes a first plurality of channels, and the second iron electrode includes a second plurality of channels; the oxygen reduction reaction electrode has a first surface facing the first plurality of channels and an opposite second surface in contact with air; the oxygen evolution reaction electrode is interleaved with the first plurality of channels of the first iron electrode, wherein at least a part of the oxygen evolution reaction electrode is arranged in the first plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode; a first electrolyte is in contact with the first iron electrode, the first surface of the oxygen reduction reaction electrode, the first plurality of channels, and the oxygen evolution reaction electrode; and wherein, the iron-air battery further includes: a second oxygen reduction reaction electrode having a first surface facing the second plurality of channels and an opposite second surface in contact with air; a second oxygen evolution reaction electrode interleaved with the second plurality of channels of the second iron electrode, wherein at least a part of the second oxygen evolution reaction electrode is arranged in the second plurality of channels in a direction perpendicular to the plane of the second oxygen reduction reaction electrode; and a second electrolyte in contact with the second iron electrode, the first surface of the oxygen reduction reaction electrode, the second plurality of channels, and the second oxygen evolution reaction electrode, wherein the electrolyte and the second electrolyte are the same or different.

19. The iron-air battery according to any one of claims 1 to 17, further comprises: a second iron electrode in contact with a second anode current collector, wherein the second iron electrode comprises a second plurality of channels; a second oxygen reduction reaction electrode having a first surface facing the second plurality of channels and an opposite second surface in contact with air; a second oxygen evolution reaction electrode interleaved with the second plurality of channels of the second iron electrode, wherein at least a portion of the second oxygen evolution reaction electrode is disposed within the second plurality of channels in a direction perpendicular to the plane of the second oxygen reduction reaction electrode; a second electrolyte in contact with the second iron electrode, the first surface of the second oxygen reduction reaction electrode, the second plurality of channels, and the second oxygen evolution reaction electrode; and an air channel disposed between the second surface of the oxygen reduction reaction electrode and the second surface of the second oxygen reduction reaction, wherein the electrolyte and the second electrolyte are the same or different.

20. An iron-air battery, comprises: an iron electrode comprising a plurality of anodes separated by a plurality of channels, wherein the plurality of anodes are electrically connected to each other; an oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air; an oxygen evolution reaction electrode interleaved with the plurality of channels, wherein at least a portion of the oxygen evolution reaction electrode is disposed within the plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode.

21. The iron-air battery according to claim 20, wherein each of the plurality of anodes is in contact with an anode current collector.

22. The iron-air battery according to claim 20 or 21, further comprising a spacer disposed between at least a portion of the iron electrode and the oxygen evolution reaction electrode.

23. The iron-air battery according to any one of claims 20 to 22, wherein the oxygen evolution reaction electrode comprises: a plurality of cathode protrusions disposed within the plurality of channels; and a main body portion connected to the plurality of cathode protrusions, wherein the main body portion is not interleaved with the plurality of channels of the iron electrode, and wherein the main body portion is disposed between the iron electrode and the oxygen reduction reaction electrode.

24. The iron-air battery according to any one of claims 20 to 23, wherein one or more of the plurality of cathode protrusions have an average length of 3 mm to 50 mm when measured from the main body portion.

25. The iron-air battery according to any one of claims 20 to 24, wherein more than 25% of the plurality of channels include an oxygen evolution reaction electrode disposed therein.

26. The iron-air battery according to any one of claims 20 to 25, wherein one or more of the plurality of channels further comprise an additive.

27. The iron-air battery according to any one of claims 20 to 26, wherein One or more of the plurality of anodes have an average length of 3 mm to 50 mm in a direction perpendicular to the plane of the oxygen reduction reaction electrode and an average width of 1 mm to 40 mm in a direction parallel to the plane of the oxygen reduction reaction electrode.

28. The iron-air battery according to any one of claims 20 to 27, wherein, Two or more of the plurality of anodes are spaced apart from each other by an average distance of 10 mm to 50 mm in a direction parallel to the plane of the oxygen reduction reaction electrode.

29. The iron-air battery according to any one of claims 20 to 28, wherein, The oxygen evolution reaction electrode includes a porous metal mesh and an oxygen evolution catalyst.

30. The iron-air battery according to any one of claims 20 to 29, wherein, Each of the plurality of anodes is in contact with a branch current collector, wherein each branch current collector is connected to a main current collector disposed parallel to the first surface of the oxygen reduction reaction electrode.

31. The iron-air battery according to any one of claims 20 to 30, wherein, Each of the plurality of anodes is in contact with a branch current collector, wherein each branch current collector is connected to a main current collector disposed parallel to the first surface of the oxygen reduction reaction electrode, wherein the main current collector is disposed outside the plane defining the active regions of the iron electrode, the oxygen evolution reaction electrode, and the oxygen reduction reaction electrode.

32. The iron-air battery according to any one of claims 20 to 31, wherein, The oxygen evolution reaction electrode is disposed in the plurality of channels between the plurality of anodes in a serpentine configuration.

33. The iron-air battery according to any one of claims 20 to 32, further comprising a second oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air, wherein, The plane of the second oxygen reduction reaction electrode is parallel to the plane of the oxygen reduction reaction electrode.

34. The iron-air battery according to any one of claims 20 to 33, wherein, The electrolyte includes a solid oxide electrolyte, a solid polymer electrolyte, a molten salt, an aqueous solution, a non-aqueous solution, a gel, or a combination thereof.

35. The iron-air battery according to any one of claims 20 to 34, wherein, The electrolyte includes an aqueous solution of an alkali metal hydroxide, an organic hydroxide, or a combination thereof.

36. The iron-air battery according to any one of claims 20 to 35, wherein, Each anode of the iron electrode has a surface density of 1 g of iron / cm² to 7 g of iron / cm² relative to a direction perpendicular to the oxygen reduction reaction electrode.

37. The iron-air battery according to any one of claims 20 to 36, wherein, Based on the total volume of the iron electrode when fully charged, the volume fraction of the electrolyte in the iron electrode is 0.5 to 0.

9.

38. An iron-air battery, comprising: An iron electrode including a plurality of anodes separated by a plurality of channels, wherein the plurality of anodes are electrically connected to each other; An oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air; An oxygen evolution reaction electrode including a plurality of cathodes interleaved with and inserted into the plurality of anodes, wherein the plurality of cathodes are disposed within the plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode, and wherein the plurality of cathodes are electrically connected to each other; and An electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode.

39. The iron-air battery according to claim 38, wherein, each anode of the plurality of anodes is in contact with an anode current collector.

40. The iron-air battery according to claim 38 or 39, further comprising a spacer disposed between at least a portion of the plurality of anodes and the plurality of cathodes.

41. The iron-air battery according to any one of claims 38 to 40, wherein, when measured in a direction perpendicular to the plane of the oxygen reduction reaction electrode, one or more of the plurality of cathodes have an average length of 3 mm to 50 mm.

42. The iron-air battery according to any one of claims 38 to 41, wherein, more than 25% of the plurality of channels include an oxygen evolution reaction electrode disposed therein.

43. The iron-air battery according to any one of claims 38 to 42, wherein, one or more of the plurality of channels further include an additive.

44. The iron-air battery according to any one of claims 38 to 43, wherein, one or more of the plurality of anodes have an average length of 3 mm to 50 mm in a direction perpendicular to the plane of the oxygen reduction reaction electrode and an average width of 1 mm to 40 mm in a direction parallel to the plane of the oxygen reduction reaction electrode.

45. The iron-air battery according to any one of claims 38 to 44, wherein, two or more of the plurality of anodes are spaced apart from each other by an average distance of 10 mm to 50 mm in a direction parallel to the plane of the oxygen reduction reaction electrode.

46. The iron-air battery according to any one of claims 38 to 45, wherein, each anode of the plurality of anodes is in contact with a branch current collector, wherein each branch current collector is connected to a main current collector disposed parallel to the first surface of the oxygen reduction reaction electrode.

47. The iron-air battery according to any one of claims 38 to 46, wherein, each anode of the plurality of anodes is in contact with a branch current collector, wherein each branch current collector is connected to a main current collector disposed parallel to the first surface of the oxygen reduction reaction electrode, wherein the main current collector is disposed outside the plane defining the active regions of the iron electrode, the oxygen evolution reaction electrode, and the oxygen reduction reaction electrode.

48. The iron-air battery according to any one of claims 38 to 47, wherein, Each of the plurality of cathodes is in contact with a cathode current collector, wherein the cathode current collector is disposed outside a plane defining an active region of the iron electrode, the oxygen evolution reaction electrode, and the oxygen reduction reaction electrode.

49. The iron-air battery according to any one of claims 38 to 48, further comprising a second oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air, wherein, a plane of the second oxygen reduction reaction electrode is parallel to the plane of the oxygen reduction reaction electrode.

50. The iron-air battery according to any one of claims 38 to 49, wherein, the electrolyte includes a solid oxide electrolyte, a solid polymer electrolyte, a molten salt, an aqueous solution, a non-aqueous solution, a gel, or a combination thereof.

51. The iron-air battery according to any one of claims 38 to 50, wherein, the electrolyte includes an aqueous solution of an alkali metal hydroxide, an organic hydroxide, or a combination thereof.

52. The iron-air battery according to any one of claims 38 to 51, wherein, each anode of the iron electrode has a surface density of 1 g / cm² to 7 g / cm² of iron relative to a direction perpendicular to the oxygen reduction reaction electrode.

53. The iron-air battery according to any one of claims 38 to 52, wherein, based on a total volume of the iron electrode when fully charged, a volume fraction of the electrolyte in the iron electrode is 0.5 to 0.

9.

54. The iron-air battery according to any one of claims 38 to 53, wherein, each of the plurality of cathodes includes an oxygen evolution catalyst.

55. An iron-air battery, comprising: an iron electrode in contact with an anode current collector, wherein the iron electrode includes a plurality of channels; an oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air; an oxygen evolution reaction electrode including a plurality of cathodes interleaved with the iron electrode, wherein the plurality of cathodes are disposed within the plurality of channels in a direction perpendicular to a plane of the oxygen reduction reaction electrode, and wherein the plurality of cathodes are electrically connected to each other; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode.

56. The iron-air battery according to claim 55, further comprising a spacer disposed between at least a portion of the iron electrode and the plurality of cathodes.

57. The iron-air battery according to claim 55 or 56, wherein, when measured in a direction perpendicular to a plane of the oxygen reduction reaction electrode, one or more of the plurality of cathodes have an average length of 3 mm to 50 mm.

58. The iron-air battery according to any one of claims 55 to 57, wherein, more than 25% of the plurality of channels include cathodes of the plurality of cathodes disposed therein.

59. The iron-air battery according to any one of claims 55 to 58, wherein, one or more of the plurality of channels further include an additive.

60. The iron-air battery according to any one of claims 55 to 59, wherein, one or more of the plurality of channels have an average length of 3 mm to 50 mm in a direction perpendicular to the plane of the oxygen reduction reaction electrode, and an average width of 1 mm to 40 mm in a direction parallel to the plane of the oxygen reduction reaction electrode.

61. The iron-air battery according to any one of claims 55 to 60, wherein, one or more of the plurality of channels have an average width of 1 mm to 40 mm in a direction parallel to the plane of the oxygen reduction reaction electrode, wherein a first width closest to the oxygen reduction reaction electrode is 1% to 500% greater than a second width farther from the oxygen reduction reaction electrode.

62. The iron-air battery according to any one of claims 55 to 61, wherein, when measured between the centers of adjacent channels, one or more of the plurality of channels are spaced apart from each other by an average distance of 10 mm to 50 mm in a direction parallel to the plane of the oxygen reduction reaction electrode.

63. The iron-air battery according to any one of claims 55 to 62, wherein, each of the plurality of channels independently has a rectangular prism shape, a cylindrical shape, a pyramid shape, or a trapezoidal prism shape.

64. The iron-air battery according to any one of claims 55 to 63, wherein, each of the plurality of cathodes is in contact with a cathode current collector, wherein the cathode current collector is disposed outside the plane defining the active regions of the iron electrode, the oxygen evolution reaction electrode, and the oxygen reduction reaction electrode.

65. The iron-air battery according to any one of claims 50 to 64, wherein, the anode current collector includes: one or more branch current collectors disposed parallel to the plurality of channels; and a main current collector connected to the one or more branch current collectors, wherein the main current collector is disposed parallel to the first surface of the oxygen reduction reaction electrode.

66. The iron-air battery according to any one of claims 50 to 65, wherein, the electrolyte includes a solid oxide electrolyte, a solid polymer electrolyte, a molten salt, an aqueous solution, a non-aqueous solution, a gel, or a combination thereof.

67. The iron-air battery according to any one of claims 55 to 66, wherein, the electrolyte includes an aqueous solution of an alkali metal hydroxide, an organic hydroxide, or a combination thereof.

68. The iron-air battery according to any one of claims 55 to 67, wherein, the iron electrode has a surface density of 1 g of iron / cm² to 7 g of iron / cm² with respect to a direction perpendicular to the oxygen reduction reaction electrode.

69. The iron-air battery according to any one of claims 55 to 68, wherein, based on the total volume of the iron electrode when fully charged, the volume fraction of the electrolyte in the iron electrode is 0.5 to 0.

9.

70. An iron-air battery, comprising: an iron electrode in contact with an anode current collector, wherein the iron electrode and the anode current collector are arranged in a spiral configuration; An oxygen reduction reaction electrode having a first surface facing the axis of rotation of the helical structure and an opposite second surface in contact with air; An oxygen evolution reaction electrode arranged in a helical structure and interleaved with the iron electrode, wherein at least a portion of the iron electrode and the oxygen evolution reaction electrode are bifilar; and An electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, and the oxygen evolution reaction electrode.

71. The iron-air battery according to claim 70, further comprising a spacer disposed between at least a portion of the iron electrode and the oxygen evolution reaction electrode.

72. The iron-air battery according to claim 70 or 71, further comprising a second oxygen reduction reaction electrode having a first surface facing the axis of rotation of the helical structure and an opposite second surface in contact with air, wherein, a plane of the second oxygen reduction reaction electrode is parallel to a plane of the oxygen reduction reaction electrode.

73. The iron-air battery according to any one of claims 70 to 72, wherein, the electrolyte includes a solid oxide electrolyte, a solid polymer electrolyte, a molten salt, an aqueous solution, a non-aqueous solution, a gel, or a combination thereof.

74. The iron-air battery according to any one of claims 70 to 73, wherein, the electrolyte includes an aqueous solution of an alkali metal hydroxide, an organic hydroxide, or a combination thereof.

75. The iron-air battery according to any one of claims 70 to 74, wherein, each anode of the iron electrode has a surface density of 1 g of iron per square centimeter to 7 g of iron per square centimeter relative to a direction perpendicular to the oxygen reduction reaction electrode.

76. The iron-air battery according to any one of claims 70 to 75, wherein, based on a total volume of the iron electrode when fully charged, a volume fraction of the electrolyte in the iron electrode is 0.5 to 0.

9.

77. An iron-air battery, comprising: an iron electrode in contact with an anode current collector, wherein the iron electrode and the anode current collector are arranged in a pleated structure; and wherein the iron electrode includes a plurality of channels between the pleats; an oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air; an oxygen evolution reaction electrode interleaved with the plurality of channels of the iron electrode, wherein at least a portion of the oxygen evolution reaction electrode is disposed within the plurality of channels in a direction perpendicular to a plane of the oxygen reduction reaction electrode, and wherein the oxygen evolution reaction electrode is arranged in a pleated structure; and an electrolyte in contact with the iron electrode, the first surface of the oxygen reduction reaction electrode, the plurality of channels, and the oxygen evolution reaction electrode.

78. The iron-air battery according to claim 77, further comprising a spacer disposed between at least a portion of the iron electrode and the oxygen evolution reaction electrode.

79. The iron-air battery according to claim 77 or 78, wherein, the oxygen evolution reaction electrode includes a porous metal mesh and an oxygen evolution catalyst.

80. The iron-air battery according to any one of claims 77 to 79, wherein, The oxygen evolution reaction electrode is disposed at a first surface of the iron electrode and further includes a second oxygen evolution reaction electrode that is interleaved and inserted with the plurality of channels of the iron electrode, wherein the second oxygen evolution reaction electrode is disposed at a second opposite surface of the iron electrode, wherein at least a portion of the second oxygen evolution reaction electrode is disposed within the plurality of channels in a direction perpendicular to the plane of the oxygen reduction reaction electrode, and wherein the second oxygen evolution reaction electrode is disposed in a corrugated configuration.

81. The iron-air battery according to any one of claims 77 to 80, further comprising a second oxygen reduction reaction electrode having a first surface facing the plurality of channels and an opposite second surface in contact with air, wherein, a plane of the second oxygen reduction reaction electrode is parallel to the plane of the oxygen reduction reaction electrode.

82. The iron-air battery according to any one of claims 77 to 81, wherein, the electrolyte includes a solid oxide electrolyte, a solid polymer electrolyte, a molten salt, an aqueous solution, a non-aqueous solution, a gel, or a combination thereof.

83. The iron-air battery according to any one of claims 77 to 82, wherein, the electrolyte includes an aqueous solution of an alkali metal hydroxide, an organic hydroxide, or a combination thereof.

84. The iron-air battery according to any one of claims 77 to 83, wherein, each anode of the iron electrode has a surface density of 1 g of iron / cm² to 7 g of iron / cm² relative to a direction perpendicular to the oxygen reduction reaction electrode.

85. The iron-air battery according to any one of claims 77 to 84, wherein, based on the total volume of the iron electrode when fully charged, a volume fraction of the electrolyte in the iron electrode is 0.5 to 0.

9.

86. A method of forming an iron-air battery according to any one of claims 1 to 19, the method comprising: forming an iron negative electrode material onto a current collector to form an iron electrode including a plurality of channels; disposing the oxygen evolution reaction electrode into one or more of the channels of the iron electrode; and assembling an oxygen reduction reaction electrode having a first surface facing the iron electrode and an opposite second surface in contact with air to form an electrode assembly.

87. The method according to claim 86, wherein, the forming includes pressing the iron negative electrode material onto the current collector to form the plurality of channels disposed in the iron electrode.

88. The method according to claim 87, wherein, the forming further includes: sintering.

89. The method according to any one of claims 86 to 88, further comprising: adding an electrolyte to the electrode assembly.

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