Lithium-air battery

Abstract

We provide metal-air batteries with improved performance. [Solution] The metal-air battery comprises a carbonaceous cathode having one or more cathode surfaces exposed to ambient air, wherein the one or more cathode surfaces contain a catalyst; an anode positioned opposite the cathode; a first electrolyte positioned between the anode and the cathode; an inorganic passivation layer formed as a film in contact with the anode; and an outer layer positioned on the passivation layer, wherein the outer layer contains one or more of the following: an ion-conducting salt or a solid second electrolyte encapsulated in a polymer.

Description

[Technical Field]

[0001] Cross-reference of related applications This patent application is a continuation-in-part application of U.S. Patent Application No. 17 / 485,888, entitled “LITHIUM-AIR BATTERY,” filed on 27 September 2021, claiming priority to said application, which in turn claims priority to U.S. Provisional Patent Application No. 63 / 211,445, entitled “LITHIUM-AIR BATTERY,” filed on 16 June 2021, all of which are assigned to the assignee of this application. The disclosures of the prior applications are incorporated herein by reference in their entirety.

[0002] Technical field This disclosure relates in general to lithium-air batteries, and more particularly to lithium-air batteries having a cathode with a pore pathway. [Background technology]

[0003] Lithium-air batteries can be used to power a wide variety of loads, from portable communication devices to electric vehicles. Lithium-air batteries use oxygen as the cathode active material, for example, oxidizing lithium at the anode during the battery discharge cycle and reducing oxygen to lithium oxide at the cathode during the same cycle. The reverse occurs during the battery charge cycle. By using oxygen supplied from the ambient air as the cathode active material, lithium-air batteries do not need to store cathode active material. While lithium-air batteries have extremely high theoretical specific energy (e.g., over 11,000 Wh / kg), the actual specific energy may be lower due to the slow rate of electron transfer and / or incomplete utilization of the cathode porous shape for oxidation-reduction reactions. Furthermore, the accumulation of lithium oxide and other by-products in the cathode during the operating cycle of a lithium-air battery can restrict oxygen inflow into the cathode and oxygen flow throughout the cathode, resulting in reduced performance. Therefore, further improvements to lithium-air batteries are desired. [Overview of the project]

[0004] This summary of the present invention is provided in a simplified form to introduce some of the concepts further described in the embodiments for carrying out the invention described below. This summary of the present invention is not intended to identify any important or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter.

[0005] An innovative embodiment of the subject matter described herein may be implemented in a lithium-air battery. This lithium-air battery may include an anode, a cathode positioned opposite the anode, an electrolyte dispersed throughout the cathode, and one or more openings configured to selectively expose the cathode to ambient air. In some embodiments, the cathode may be formed from an array of carbonaceous structures and may include a plurality of pores defined by a first group of carbonaceous structures, a plurality of interconnected pathways defined by a second group of carbonaceous structures, and one or more cavities formed within or accompanying each of the pathways. In some examples, the pores may be configured to allow oxygen supplied from ambient air to enter the cathode, the interconnected pathways may be configured to diffuse oxygen throughout the cathode, and each of the cavities may be configured to store lithium metal. In some embodiments, the anode is composed of lithium metal.

[0006] In various embodiments, each carbonaceous structure may be based on an aggregate of carbon nanoonion (CNO) particles of a corresponding group. In some examples, each carbonaceous structure may comprise multiple interconnected graphene flakes. In other examples, each carbonaceous structure may comprise one or more of flat graphene, wrinkled graphene, curved graphene, or porous non-hollow spherical particles. In some embodiments, the CNO particles have a radius between approximately 5 nanometers and 500 nanometers. In other embodiments, at least some of the CNO particles of the first group of carbonaceous structures have a radius greater than 100 nanometers and contain multiple cavities. In some other examples, each carbonaceous structure comprises a three-dimensional (3D) stack of graphene nanosheets.

[0007] In some embodiments, at least a portion of the CNO particles of the first group with carbonaceous structures may be configured to be hydrophobic. In some examples, the hydrophobic CNO particles of the first group with carbonaceous structures inhibit the movement of water droplets along the surface toward one or more of the pores. In other embodiments, at least a portion of the CNO particles of the second group with carbonaceous structures may be configured to be hydrophilic. In some examples, the hydrophilic CNO particles of the second group with carbonaceous structures allow water droplets to form a continuous water film along each surface of the hydrophilic CNO particles. In some embodiments, the continuous water film may be in equilibrium due to cohesive forces within the continuous water film and adhesive forces between the continuous water film and each surface of the hydrophilic CNO particles. The surface tension associated with the continuous water film prevents water droplets in the continuous water film from accumulating on the cathode.

[0008] In some examples, the lithium-air battery may also include a plurality of other interconnected pathways defined by a third group of carbonaceous structures. In some examples, the plurality of other interconnected pathways may be configured to remove undesirable by-products from at least a portion of the interconnected pathways defined by a second group of carbonaceous structures. In other examples, the lithium-air battery may include a separator positioned between the anode and the cathode.

[0009] In some other embodiments, the lithium-air battery may also comprise a protective layer disposed on the anode. In some examples, the protective layer may comprise: a polymer network deposited on one or more exposed surfaces of the anode, wherein the polymer network comprises a carbonaceous structure grafted with a plurality of fluorinated polymer chains cross-linked to each other; and a lithium fluoride (LiF) film formed from the polymer network and lithium supplied by the anode. In some aspects, the lithium-air battery may also comprise an outer layer deposited on the lithium fluoride film. The outer layer may comprise one or more of a polymer or an epoxy-encapsulated ionic conductor.

[0010] The details of one or more embodiments of the subject matter described in the present disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will be apparent from the description, the drawings, and the claims. It should be noted that the relative dimensions in the following drawings may not be drawn to scale.

[0011] The drawings described below are for illustrative purposes only. The drawings are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] [Figure 1] A diagram illustrating an exemplary battery according to some embodiments is shown. [Figure 2] A diagram illustrating a cathode of the battery of FIG. 1 according to some embodiments is shown. [Figure 3] A diagram of a polymer network according to some embodiments is shown. [Figure 4] A and B show micrographs of various carbonaceous materials according to some embodiments. [Figure 5A] An SEM micrograph of graphene powder according to some embodiments is shown. [Figure 5B]Shows SEM micrographs of nodular carbon produced by a thermal process, according to some embodiments. [Figure 5C] Shows SEM micrographs of carbon dioxide (CO₂)-treated carbon, according to some embodiments. [Figure 5D] Shows SEM micrographs of carbon dioxide (CO₂)-treated carbon, according to some embodiments. [Figure 6] Shows micrographs of three-dimensional (3D) graphene after carbon dioxide (CO₂) treatment, according to some embodiments. [Figure 7] Shows a graph illustrating an exemplary distribution of pore volume versus pore width of exemplary carbonaceous particles, according to some embodiments. [Figure 8A] Shows an illustration illustrating the hydrophobic behavior of few-layer graphene (FLG) having 3 to 15 carbon atom layers. [Figure 8B] Shows an illustration illustrating exemplary flooding of a lithium-air battery. [Figure 9A] Shows an illustration illustrating a charged state of a lithium-air battery. [Figure 9B] Shows an illustration illustrating a discharged state of a lithium-air battery. [Figure 10] Shows an illustration illustrating various types of FLG. [Figure 11] Shows 1100, an illustration illustrating an aggregate formed from a plurality of single particles. DETAILED DESCRIPTION OF EMBODIMENTS FOR CARRYING OUT THE INVENTION

[0013] Like reference numerals and reference signs in different drawings refer to like elements.

[0014] The following description covers several exemplary embodiments for the purpose of illustrating the innovative aspects of this disclosure. However, those skilled in the art will readily recognize that the teachings herein can be applied in numerous different ways. The embodiments described may be implemented in any type of electrochemical cell, battery, or battery pack and may be used to compensate for various performance-related defects. Accordingly, the embodiments disclosed should not be limited to the examples provided herein, but rather encompass all embodiments intended by the appended claims. Furthermore, well-known elements of this disclosure will not be described in detail or will be omitted in order not to obscure the relevant details of this disclosure.

[0015] As used herein, “porosity” refers to the ratio of the volume of pores or voids in a material to its geometric volume. Porosity can be measured using appropriate methods, including, but not limited to, the BET method and gas permeability measurements. As used herein, the terms “about” and “near” are used to allow for margins, for example, to indicate that a given value at an endpoint of a numerical range may be “slightly above” or “slightly below” the endpoint. The degree of margin for a particular variable can be readily determined by a person skilled in the art based on the context. As used herein with respect to an identified characteristic or situation, “substantially” means a degree of deviation that is small enough not to impair the identified characteristic or situation to a measurable degree. The exact degree of acceptable deviation may depend on the specific context in some cases.

[0016] Furthermore, numerical data such as concentration and quantity may be presented in range form in this specification. It should be understood that such range forms are used solely for convenience and conciseness, and should be interpreted flexibly to include not only the numerical limits explicitly stated as range restrictions, but also all individual numerical values ​​or subranges contained within that range, as if each numerical value and subrange were explicitly stated. For example, a numerical range of approximately 1 to approximately 2.5 should be interpreted to include not only the explicitly stated limit of 1 to approximately 2.5, but also individual numerical values ​​such as 2, 3, and 4, and subranges such as 1 to 3, 2 to 4, etc. The same principle applies to ranges that specify only one number, such as "less than approximately 2.5," which should be interpreted as encompassing all of the above values ​​and ranges. Furthermore, such interpretation should apply regardless of the breadth of the range or characteristic described.

[0017] A battery typically (but not limited to) includes several electrochemical cells that can be connected in series and / or parallel networks to power a wide variety of devices such as mobile phones, laptop computers, electric vehicles (EVs), factories, and buildings. The electrolyte is a key component in electrochemical cells and all types of batteries, particularly lithium-based batteries, and its performance can be limited by the type of electrolyte used or by uncontrolled battery side reactions. Consequently, optimizing the electrolyte can improve the overall performance of each battery, including its cycle life, specific discharge capacity, discharge capacity retention, safety, and lifespan.

[0018] Lithium-air batteries use oxygen supplied from the ambient air as the cathode active material and lithium metal as the anode. The use of a porous cathode in a lithium-air battery allows gaseous oxygen supplied from the ambient air to diffuse throughout the cathode and react with lithium ions during the battery's discharge reaction, and allows the gaseous oxygen to return to the ambient air during the battery's charging process. By using oxygen as the cathode active material, lithium-air batteries, whether primary or rechargeable, can offer greater energy storage capacity than other types of batteries due to the abundance of oxygen available in the cathode. In other words, by using oxygen as the cathode active material, lithium-air batteries do not need to store cathode active material, and therefore their specific energy and energy storage capacity are not limited by the amount of cathode active material that can be stored in the cathode.

[0019] In conjunction with the cycle of a lithium-air battery, oxygen reduction can occur at the three-phase boundary where the solid (cathode), liquid (electrolyte), and gaseous (oxygen) are in contact with each other. In an alternative configuration, such a configuration provides available pathways for lithium ions to move and / or be transported through the liquid electrolyte, available pathways for gaseous oxygen to move and / or be transported through the porous pathways in the cathode, and available pathways for electrons to be conducted through the carbonaceous material in the cathode. Thus, in a lithium-air battery, a highly porous cathode structure can be used to increase the available electrochemical reaction area, thereby increasing the current conduction from the lithium-air battery.

[0020] During continuous discharge and charge cycles of a lithium-air battery, discharge products generated at the cathode can kinetically affect battery performance, potentially reducing the battery's specific energy, energy capacity, and lifespan. For example, chemical reactions between lithium ions and oxygen at the cathode can produce lithium dioxide (Li2O) and lithium superoxide (Li2O2). Lithium dioxide, and in some cases lithium superoxide, are insoluble in certain types of electrolytes used in lithium-air batteries and therefore cannot diffuse away from the cathode through the electrolyte. Instead, these lithium oxide products can become trapped within the cathode and accumulate in various pores, particularly pore inlets (e.g., pore "mouths") and pathways, which are involved in supplying oxygen to the cathode from ambient air during the battery's operating cycle. The unending accumulation of such by-products can clog or block these pores and / or pathways, thereby reducing the amount of oxygen available at the cathode to participate in the chemical reactions related to current generation within the lithium-air battery.

[0021] Aspects of this disclosure relate to situations in conventional lithium-air batteries where lithium oxide products may not be able to be removed from the cathode, and therefore, within the pores and / or pathways of the cathode... It is recognized that the accumulation of these lithium oxide products may not be controllable. According to various embodiments of the subject disclosed herein, an interconnected network of storage pathways and storage cavities of various dimensions may be provided within the cathode of a lithium-air battery to extract or remove the accumulation of these products from pores and / or pathways involved in drawing oxygen supplied from the ambient air into the cathode, thereby increasing the amount of oxygen that these pores and / or pathways can deliver to the cathode during the charge-discharge cycle of the lithium-air battery. By increasing the amount of oxygen available in the cathode to react with lithium oxide and lithium ions during the charge-discharge cycle of the battery, respectively, embodiments of the subject disclosed herein may increase the specific energy capacity and effective life of the lithium-air battery. In some examples, the shape, size, and orientation of these pathways may be defined by porous, non-hollow carbonaceous spherical particles that coalesce with each other within the cathode to form a larger porous carbonaceous structure.

[0022] Figure 1 shows a diagram illustrating an exemplary battery 100 according to several embodiments. The battery 100 may be a lithium-air battery that fluidly communicates with ambient air 170 accompanying the environment outside the battery 100. In some embodiments, the battery 100 has a body 105 which may include a cathode 110, an anode 120 positioned opposite the cathode 110, an electrolyte 130, a solid electrolyte interphase interface (SEI) layer 140, a polymer network 150, and a barrier layer 160. In some other embodiments, one or more of the SEI layer 140 or the polymer network 150 may be omitted from the battery 100. Although not shown in Figure 1 for simplicity, the battery 100 may include a first substrate positioned adjacent to the cathode 110, on which the cathode 110 may be placed, and may further include a second substrate positioned adjacent to the anode 120, on which the anode 120 may be placed. In some embodiments, the first and second substrates may be solid copper metal foils that are selectively etchable, coatable with carbonaceous materials, and / or treatable with materials suitable for changing or adjusting the energy capacity and specific energy of the battery 100. In other embodiments, the first and second substrates may include, or be formed from, a selection of aluminum, copper, nickel, titanium, stainless steel, and / or one or more carbonaceous materials.

[0023] In some other embodiments, the first and second substrates may be at least partially foam-based, selected from one or more of the following: metal foam, metal web, metal screen, perforated metal, or sheet-based 3D structures. In some embodiments, the first and second substrates may be metal fiber mats, metal nanowire mats, conductive polymer nanofiber mats, conductive polymer foams, conductive polymer coated fiber foams, carbon foams, graphite foams, or carbon aerogels. In some other embodiments, the first and second substrates may be carbon xerogels, graphene foams, graphene oxide foams, reduced graphene oxide foams, carbon fiber foams, graphite fiber foams, exfoliated graphite foams, or any combination thereof. The specific composition and configuration of the first and second substrates may vary depending on the specific end-use application and / or performance requirements of the battery 100.

[0024] The cathode 110 can function as the positive electrode of the battery 100. In some embodiments, the cathode 110 may include a plurality of interconnected pores 112 and pathways 114 that can diffuse or distribute oxygen supplied from the ambient air 170 throughout the cathode 110 during the operating cycle of the battery 100. The pores 112 and pathways 114 may be defined by various porous non-hollow carbonaceous spherical particles that are positioned, distributed, or otherwise arranged across one or more portions of the cathode 110. The group of porous non-hollow carbonaceous spherical particles may coalesce to form a larger carbonaceous structure within the cathode 110 (for simplicity, both the porous non-hollow carbonaceous spherical particles and the larger carbonaceous structure are shown in Figure 1). (Not done). Porous non-hollow carbonaceous spheres (NHCS) can bond to each other at various concentration levels to form larger carbonaceous structures, with higher concentration levels associated with higher electrical conductivity. In various embodiments, the first group of pores 112 and pathways 114 may be arranged and sized to allow oxygen supplied from ambient air 170 to enter and diffuse throughout the cathode 110, and the second group of pathways 114 and cavities 116 may be arranged and sized to remove undesirable chemical byproducts 180 from the first group of pores 112 and pathways 114. In some examples, the second group of pathways 114 and cavities 116 can retain or store the byproducts 180 removed from the first group of pores 112 and pathways 114. In this way, the second group of pathways 114 and cavities 116 can separate by-products 180 that may accumulate in the cathode 110 and / or by-products 180 that may adhere to the surface of the first group of pores 112 and pathways 114 from the first group of pores 112 and pathways 114. When used herein, as will be described in more detail with respect to Figure 2, the terms “transport pores” and “transport pathways” may refer to the first group of pores 112 and pathways 114, and the terms “storage pathways” and “storage cavities” may refer to the second group of pathways 114 and cavities 116.

[0025] In various embodiments, the cathode 110 may include one or more metal catalysts that can improve the reaction rate of the oxygen reduction process within the battery 100, for example, to increase the specific capacity of the battery 100. For example, in some embodiments, manganese, cobalt, ruthenium, platinum, silver, or a mixture of cobalt and manganese can be used as catalysts for the cathode 110, either in pure metallic form or as compounds formed with additional metals or other elements. In some examples, the use of a manganese oxide catalyst within the cathode 110 can result in a specific capacity of carbon of approximately 3,137 mA·H / g.

[0026] The anode 120 can function as the negative electrode of the battery 100. In some embodiments, the anode 120 may be formed as a single layer of lithium metal (e.g., element lithium) that does not contain any carbon or carbonaceous material. That is, unlike the anodes used in many conventional lithium-air batteries, the anode 120 of the battery 100 does not contain a carbon scaffold or other carbonaceous material, but instead contains lithium metal. As a result, the anode 120 may supply more lithium for oxidation than a carbon-based anode of similar size, thereby increasing the energy capacity and specific energy of the battery 100 compared to such conventional lithium-air batteries. In some examples, the anode 120 may function with a solid electrolyte configured to suppress the formation and growth of lithium dendrites from the anode 120.

[0027] The electrolyte 130 may be dispersed throughout the cathode 110 or in contact with one or more surfaces of the anode 120. The electrolyte 130 can be any suitable material or mixture capable of transporting lithium ions between the anode 120 and the cathode 110 during the operating cycle of the battery 100. In some embodiments, the electrolyte 130 may be a liquid-phase electrolyte (e.g., an aprotic liquid-phase electrolyte solution). In some other embodiments, the electrolyte 130 may be a solid polymer, a gel polymer (such as an inorganic glassy or ceramic electrolyte), among several examples. In some examples, the electrolyte 130 may start in a gel phase state and then solidify after activation of the battery 100.

[0028] The SEI layer 140 may be placed on one or more surfaces of the anode 120, adjacent to or in contact with the electrolyte 130. In some examples, the SEI layer 140 may be formed on the anode 120 in response to the reaction between lithium supplied by the anode 120 and the electrolyte 130 during the operating cycle of the battery 100. The SEI layer 140 may contain tin, manganese, molybdenum, and / or fluorine compounds. Molybdenum provides... The cation interacts with the anion provided by the fluorine compound to form tin(II) fluoride (SnF2), manganese(II) fluoride (MnF2), silicon nitride (Si3N4), lithium nitride (Li3N), lithium nitrate (LiNO3), lithium phosphate (Li3PO4), manganese oxide, or lithium lanthanum zirconium oxide (LLZO,Li7La3Zr2O). 12 ) and others (but not limited to) may be produced as one or more types or structures of salts.

[0029] In some embodiments, the SEI layer 140 may include a mechanical strength enhancer (not shown for simplicity) that provides structural support for the battery 100. In some examples, the mechanical strength enhancer may also prevent lithium dendrites from forming on and / or growing from the anode 120. The mechanical strength enhancer may be formed as a protective coating on the anode 120 and may include one or more carbon allotropes, carbon nanoonions (CNOs), nanotubes (CNTs), reduced graphene oxide, graphene oxide (GO), and / or carbon nanodiamonds. In some other embodiments, the SEI layer 140 may not include any mechanical strength enhancer.

[0030] The polymer network 150 may be deposited or formed on one or more exposed surfaces of the anode 120. In some embodiments, the polymer network 150 may be evenly distributed across one or more portions of the SEI layer 140 and may include various carbonaceous structures grafted with crosslinked fluorinated polymer chains (for simplicity, neither the carbonaceous structures nor the fluorinated polymer chains are shown in Figure 1). Specifically, a carbonaceous material may be grafted with fluorinated polymer chains and deposited on one or more exposed surfaces of the anode 120. The fluorinated polymer chains can be crosslinked to form the polymer network 150 when they complex with lithium metal from the anode 120 via a Wurtz reaction. Once formed in this way, the polymer network 150 is formed on the anode 1The formation of lithium dendrites from 20 can be suppressed. In some embodiments, the carbonaceous material forming at least a portion of the polymer network 150 may include (but not limited to) graphene, multilayer graphene, multilayer graphene, graphene nanoparticles, 3D graphene scaffolds, etc. The carbonaceous material may be chemically grafted with fluorinated polymer chains via carbon-fluorine (CF) bonds. In some embodiments, these CF bonds may chemically react with lithium metal from anode 120 to produce highly ionic carbon-lithium bonds (C-Li). These C-Li bonds may react with CF bonds between the carbonaceous material and the fluorinated polymer chains to form new carbon-carbon bonds. These novel carbon-carbon bonds may also be used to crosslink polymer chains to form the polymer network 150.

[0031] In some embodiments, the polymer network 150 may include a layer of lithium fluoride (not shown for simplicity). The lithium fluoride layer may be formed in accordance with the chemical bonding between lithium ions 122 and fluoride ions. In some embodiments, the lithium fluoride layer may also include lithium fluoride produced by the “novel” carbon-carbon bonding described above. In some examples, the lithium fluoride layer may be uniformly distributed along the outer periphery of the polymer network 150 so that lithium ions 122 are less likely to bond and / or react with each other, and more likely to bond and / or react with fluorine atoms utilized by the fluorinated polymer chains embedded in the polymer network 150. In some other embodiments, the battery 100 may not include the polymer network 150.

[0032] The barrier layer 160 may be detachably placed on the outer surface of the battery body 105 near the cathode 110. When the battery 100 is in a dormant state (for example, in a warehouse or on a product shelf before purchase and activation by a user), the barrier layer 160 can be removed from the battery body 105. The barrier layer 160 may be attached and arranged such that the pores 112 and pathways 114 associated with the cathode 110 are sealed to the ambient air 170. In this way, the barrier layer 160 can prevent oxygen supplied from the ambient air 170 from entering the cathode 110 and reacting with the lithium in the battery 100. In this way, the barrier layer 160 can prevent accidental activation of the battery 100 while it is in a dormant state.

[0033] In some embodiments, the user can activate the battery 100 by removing the barrier layer 160 from the outer surface of the battery body 105. For example, if the barrier layer 160 is removed or absent for any other reason, oxygen supplied from the ambient air 170 can enter the pores 112 and pathways 114 formed in the cathode 110 and diffuse throughout the cathode 110. As already mentioned, oxygen can be used to oxidize the lithium supplied from the anode 120 during the battery discharge cycle and can be used for oxygen reduction reactions during the battery discharge cycle. Therefore, by removing the barrier layer 160 from the outer surface of the battery body 105, the battery 100 is activated so that oxygen supplied from the ambient air 170 can enter the cathode 110 and participate in various chemical reactions inside the battery 100.

[0034] In some embodiments, the battery 100 may include a separator (not shown for simplicity) that can further suppress dendrite formation on the anode 120 and dendrite growth from the anode 120. The separator may have ionic conductivity similar to that of the electrolyte 130, and nevertheless still suppress lithium dendrite formation. In some embodiments, the separator may be formed from a ceramic-containing material that does not chemically react with metallic lithium, and as a result may be used to control lithium ion transport through the separator while preventing short circuits by obstructing the flow or passage of electrons through the electrolyte 130.

[0035] As already mentioned, if battery 100 is configured to operate as a lithium-air battery, the oxygen supplied from the ambient air 170 Cathode active material It is used as follows. By using oxygen supplied from the ambient air 170, it is possible to ensure a sufficient supply of active material to operate the lithium-air battery 100 without storing any active material in the cathode 110. Specifically, during the battery discharge cycle, lithium supplied from the anode 120 is oxidized by the ambient air 170 to produce lithium ions 122 and free electrons 124. The half-reactions that occur at the anode 120 can be expressed as follows. Li⇔Li + +e - (Formula 1)

[0036] Lithium ions 124 move from the anode 120 to the cathode 110 via the electrolyte 130. Oxygen gas (O2) supplied from the ambient air 170 enters the transport pore 112 of the cathode 110 and diffuses throughout the cathode 110 through the transport pathway 114. The oxygen gas reacts with lithium ions 122 in the cathode 110 to produce lithium oxide. Free electrons 124 move from the anode 120 to the cathode 110 via the external circuit, thereby supplying a current that can power the load 190 coupled to the external circuit. The half-reactions occurring in the cathode 110 can be expressed as follows: 4Li + O2 → 2Li2O(E 0 =2.9V) (Formula 2) 2Li + O2 → Li2O2(E 0 =3.1V) (Formula 3)

[0037] Between each battery charging cycle, the above process is reversed. That is, oxygen supplied from the ambient air 170 donates electrons to at least some of the lithium oxide in the cathode 110, generating lithium ions 122 and electrons 124. The electrochemical potential between the anode 120 and the cathode 110 can return these lithium ions 122 from the cathode 110 through the electrolyte 130 to the anode 120. The lithium ions 122 are is accumulated in the node 120, and lithium is plated on the anode 120, whereby the lithium supply to the anode 120 can be replenished.

[0038] As already mentioned, the chemical reaction between lithium ions 122 and oxygen at the cathode 110 produces lithium oxide as an unwanted by-product, such as lithium peroxide (Li₂O₂) and lithium superoxide (Li₂O). Lithium oxide is insoluble in aprotic electrolytes and therefore cannot be dispersed from the cathode 110 through the electrolyte 130. Instead, these undesired by-products are confined within the cathode 110 and may adhere to the transport pores 112 and transport paths 114 in the cathode 110 after each discharge cycle of the battery 100. Over time, these by-products accumulate on and / or in the various transport pores 112 and transport paths 114 that are involved in diffusing oxygen from ambient air 170 throughout the cathode 110, which may clog or block the various transport pores 112 and transport paths 114, thus reducing the amount of oxygen available to react with lithium supplied from the anode 120. The resulting reduction in the amount of available oxygen may reduce the amount of lithium ions 122 and free electrons 124 generated during the operating cycle of the battery 100, and therefore may reduce the amount of current that can be delivered to the load 190.

[0039] In some aspects, the formation of these by-products can be expressed as follows. Li + +e - +O₂+ * →LiO₂ (Equation 4) Li + +e - +LiO₂ * →Li₂O₂ * (Equation 5) Here, "*" represents a neutral Li vacancy on the surface of the lithium peroxide (Li₂O₂) by-product.

[0040] Various embodiments of the subject disclosed herein may remove lithium oxide and lithium peroxide generated during the operation of the battery 100 from the transport pores 112 and transport paths 114 during the operating cycle of the battery 100, thereby enabling the transport pores 112 and transport paths 114 to supply a sufficient amount of oxygen to generate lithium ions and free electrons during the battery 100 cycle. In some embodiments, the cathode 110 may include a network of storage paths and storage cavities that are in fluid communication with the network of transport pores 112 and transport paths 114. In some embodiments, the network of storage paths may remove undesirable by-products from the transport pores 112 and transport paths 114, as will be described in more detail with reference to Figure 2, and the network of storage cavities may store or otherwise retain the undesirable by-products removed from the network of transport pores 112 and transport paths 114. In this way, lithium oxide and lithium peroxide generated during the operation of the battery 100 cannot accumulate in or near the openings of the pores 112, and therefore may not interfere with the supply of oxygen provided from the ambient air 170 to activate and / or operate the battery 100.

[0041] Figure 2 shows diagrams illustrating cathode 200 according to several embodiments. Cathode 200 may be an example of cathode 110 in Figure 1, or it may be formed from a scaffolding carbonaceous material 224 (e.g., a composite aggregate of several layers of graphene other than a plurality of carbonaceous structures 225 and / or a group of porous non-hollow carbonaceous spherical (NHCS) particles 226). In some embodiments, the scaffolding carbonaceous material 224 and / or plurality of carbonaceous structures 225 associated with cathode 110 may exhibit increased resistance to oxidation during battery charging cycles (compared to conventional lithium-air batteries), which may result in longer operating times for lithium-air batteries. In some examples, the graphenized material associated with the carbonaceous structures 225 may be functionalized with polar groups to improve surface wetting within each carbonaceous structure 225.

[0042] In some embodiments, the cathode 200 may include a plurality of pores 210a-210b, a plurality of transport pathways 220, a plurality of storage pathways 221, and a plurality of cavities 230a-230d formed throughout the cathode 200. In some embodiments, the pores 210a-210b may be examples of pores 112 in Figure 1, the pathways 220 and 221 may be examples of pathways 114 in Figure 1, and the cavities 230a-230d may be examples of cavities 116 in Figure 1. That is, the pores 210a-210b and pathways 220 may be transport holes and transport pathways, respectively, through which oxygen 171 from the ambient air 170 can enter the inner portion of the cathode 200. The pores 210a-210b and pathways 220 may also be used to return oxygen 172 to the ambient air 170. The pathways 221 and cavities 230a-230d may also be transport pathways and transport cavities, respectively, through which undesirable by-products can be removed from transport pores 210a-210b and transport pathway 220. The example in Figure 2 shows only two transport pores 210a-210b, several transport pathways 220 and storage pathway 221, and four cavities 230a-230d, but in other embodiments, the cathode 200 may include a different number of transport pores 210a-210b, transport pathways 220, storage pathways 221, and cavities 230a-230d.

[0043] In some embodiments, the transport holes 210a-210b and transport pathway 220 may form a transport network that is in fluid communication with a storage network formed by the storage pathway 221 and storage cavities 230a-230d. For example, during the operating cycle of the battery 100, oxygen 171 supplied from the ambient air 170 may enter the cathode 200 through the transport hole 210a and be distributed throughout the cathode 200 by the transport pathway 220. Oxygen 172 released from the cathode 200 may return to the ambient air 170 via the transport pathway 220 and transport hole 210b. In this way, the transport holes 210 and transport pathway 220 may supply oxygen from the ambient air 170 to the cathode 200 to ensure that a sufficient amount of oxygen is available for the oxidation and reduction processes associated with the operating cycle of the battery 100. The storage pathway 221 may remove undesirable by-products (e.g., lithium dioxide and lithium superoxide) from the transport holes 210 and transport pathway 220. In some examples, the storage pathway 221 may direct these undesirable by-products toward one or more of the storage cavities 230a to 230d that can hold or store these undesirable by-products. In this way, the storage pathway 221 and the storage cavities 230a to 230d can prevent the undesirable by-products from accumulating in the cathode 200 and blocking one or more transport pores 210 and / or transport pathways 220.

[0044] The transport pores 210a-210b, transport pathway 220, storage pathway 221, and storage cavities 230a-230d may have their shape, size, and / or orientation defined by a plurality of carbonaceous structures 225 distributed throughout the cathode 200. In various embodiments, some of the carbonaceous structures 225 may be tuned to exhibit hydrophilic properties, for example, to attract and / or retain water vapor associated with the operation of a lithium-air battery. In some examples, the exposed surfaces of the first group or plurality of carbonaceous structures 225 may be tuned to hydrophilicity using a “bottom-up” synthesis procedure, such as autonucleation from a carbon-containing vapor stream in a reaction vessel. As already mentioned, each of the carbonaceous structures 225 may be formed by the accretion of corresponding groups of porous non-hollow carbonaceous spherical (NHCS) particles 226. In some embodiments, the transport pores 210 may have main dimensions (e.g., width or diameter) in an approximate range of 0.6 nanometers (nm) to 6.6 nm to hold reaction byproducts, and the transport pathways 220 may each have dimensions of about 5.0 to 10.0 microns (or other suitable dimensions that allow oxygen gas supplied from the ambient air 170 to flow into the cathode 200 and diffuse throughout the cathode 200). The disclosed dimensions can be adapted to wetting (e.g., by condensation of vapor onto each surface) of the exposed surfaces (e.g., 3.0 nm to 5.5 nm, 5.5 nm to 6.0 nm, etc.) of at least some of the carbonaceous structures 225. In addition, the polarity of the exposed surfaces of at least some of the carbonaceous structures 225 Controlling this can facilitate and / or reduce the evaporation of the solvent (e.g., carbonates, ethers, and / or esters, and / or aprotic solvents). In this way, the surface interaction between at least a portion of the solvent introduced into cathode 200 and the exposed surface of carbonaceous structure 225 can be adjusted or regulated.

[0045] Each storage pathway 221 may have a diameter of approximately 0.1 to 5.0 microns (or other suitable dimensions that allow lithium oxide byproducts to be removed from the transport pathway 220 and deposited in one or more of the cavities 230a to 230d). In some embodiments, one or more of the transport pathways 220 may be connected to one or more of the storage pathways 221 associated with the storage site network. For example, as shown in Figure 2, each of the storage cavities 230a to 230d associated with the storage site network may be connected to the pores 210 and / or transport pathways 220 via the corresponding storage pathways 221 that extend throughout the cathode 110. In some embodiments, the discharge capacity of the battery 100 may be based at least in part on the diameter of the storage pathways 221 relative to the diameter of the transport pathways 220. For example, a transport pathway 220 with a relatively large diameter may induce more oxygen 171 per unit time than a transport pathway 220 with a relatively small diameter.

[0046] Aspects of the present disclosure recognize that some undesirable by-products (e.g., lithium oxide) may remain within a certain distance after being generated during battery operation and therefore may not travel a sufficient distance to reach one of the transport paths 220 (or storage paths 221). These undesirable by-products may remain on the outer portion of the cathode 120 and clog the openings of the pores 210a-210b. Therefore, in some embodiments, the width or diameter of the openings of the pores 210a-210b may be increased, for example, to reduce the possibility of clogging by these undesirable by-products, thereby increasing the discharge rate of a lithium-air battery, such as battery 100 in Figure 1.

[0047] In some embodiments, each carbonaceous structure 225 may comprise a plurality of NHS particles 226, and each NHS particle 226 may comprise a stack of 3 to 15 graphene nanosheets (not shown in Figure 2) and / or be formed from such stacks. Each graphene nanosheet may have a major dimension of less than 1 μm, and some graphene nanosheets may contain mesopores. For example, each mesopore may be approximately 1cc / g (For example, 1.5 cc / g ~2.0 cc / g ) may have a larger volume. During manufacturing, cathode 200 may be formed from carbon-containing free radical species that self-nucleate without requiring seed particles to form an intrinsic 3D carbonaceous structure containing nitrogen and / or sulfur-doped graphene nanosheets. In some embodiments, cathode 200 may be treated with ozone (O3) during manufacturing to define a carbonaceous structure therein, thereby the cathode may have a volume greater than 5m 2 / g ~3,000m 2 / g The surface area will be within an approximate range. In addition, the cathode 200 may include one or more surfaces exposed to ambient air 170 so that catalysts (e.g., manganese oxide, nickel oxide, cobalt, platinum, gold, etc.) can be deposited on the surface.

[0048] Heteroatom doping of graphene used to generate NHCS particles 225 in Figure 2 can improve the overall electroactivity of cathode 200. For example, nitrogen-doped carbon nanotubes with up to 10.2 atomic percent (at%) of nitrogen may be used as the fabrication cathode material for NHCS particles 225 of cathode 200. Furthermore, pyridine-type nitrogen-rich carbon materials can be used to form NHCS particles 225 and provide oxygen adsorption. For example, in-plane pyridine-type nitrogen may exhibit higher activity in promoting lithium peroxide cluster nucleation compared to original nitrogen and / or graphite nitrogen. By doping the carbonaceous material of the cathode with multiple types of heteroatoms, many bifunctional cathode materials such as nitrogen-doped carbon nanotubes (CNTs), nitrogen-doped graphene, sulfur-doped graphene, and nitrogen-, sulfur-co-doped graphene can be used as cathodes. This may also be applied to Code 200. Nitrogen doping may improve the catalytic activity of carbonaceous materials by manipulating the local electronic structure, thereby providing a higher concentration of electroactive sites per unit volume. Sulfur-doped graphene may also provide cycle stability for the stability of the -CSC- and -C==S- structures.

[0049] NHS particles 222 for cathode 110 may be synthesized using 3D nanoporous undoped, N-doped, and S-doped graphene materials by nanoporous metal-based chemical vapor deposition (CVD) using benzene, pyridine, or thiophene as carbon, nitrogen, and sulfur sources, respectively. Alternatively, NHCS particles 225 for cathode 200 may be produced using metal-free graphene, providing capacities of 10,400 mAh / g and capacities of up to 300 cycles at 1,000 mAh / g. When composed of such nanoporous graphene, the charge overpotential of cathode 200 may be relatively high, resulting in relatively low energy efficiency. This problem can be addressed by tuning the surface chemistry of the nanoporous graphene and / or integrating it with compatible redox mediators that facilitate charging.

[0050] Figure 3 shows an exemplary polymer network 310 in several embodiments. In some embodiments, the polymer network 310 may be an example of the polymer network 150 in Figure 1. The polymer network 310 may be nonconductive and may be located on the anode 302. Thus, the polymer network 310 can avoid additional lithium plating on exposed lithium-containing surfaces (e.g., surfaces raised relative to the bulk of the anode 302). The anode 302 may be formed as an alkali metal layer having one or more exposed surfaces containing any number of alkali metal-containing nanostructures or microstructures. The alkali metals may include (but are not limited to) lithium, sodium, zinc, indium, and / or gallium. The anode 302 may release alkali ions during the battery's operating cycle.

[0051] A layer of carbonaceous material 314 may be deposited on one or more exposed surfaces of the anode 302 by grafting it with fluorinated polymer chains. Grafting may be based on activating the carbonaceous material with one or more radical initiators, such as benzoyl peroxide (BPO) or azobisisobutyronitrile (AIBN), and then reacting it with monomer molecules. The polymer network 310 may be based on the mutually crosslinked fluorinated polymer chains and carbonaceous material of layer 314, such that layer 314 is consumed during the generation of the polymer network 310. In some embodiments, the polymer network 310 may have a thickness of about 0.001 μm to 5 μm and may contain about 0.001% to 2% by weight of fluorinated polymer chains. In some other embodiments, the polymer network 310 may comprise, in between about 5% to 100% by weight, a plurality of carbonaceous materials grafted with fluorinated polymer chains, and the remaining fluorinated polymer, or one or more non-fluorinated polymers, or one or more crosslinkable monomers, or a combination thereof. In one embodiment, the carbonaceous material grafted with fluorinated polymer chains may comprise 5% to 50% by weight of fluorinated polymer chains and the remaining carbonaceous material.

[0052] During the battery cycle, carbon-fluorine bonds within the polymer network 310 can chemically react with lithium metal to convert into carbon-lithium bonds (C-Li). These C-Li bonds then further crosslink the polymer network by successively reacting with other carbon-fluorine bonds within the polymer network 310 via the Wurtz reaction 350 to form new carbon-carbon (CC) bonds, thereby generating alkali metal-containing fluorides, such as lithium fluoride (LiF). The additional polymer network crosslinking resulting in the uniform formation of alkali metal-containing fluorides suppresses alkali metal dendrite formation 340 associated with the anode 302, thereby improving battery performance and lifespan. In one embodiment, the grafting of fluorinated m / acrylate (FMA) onto one or more exposed graphene surfaces of the carbonaceous material within layer 314 may be carried out in an organic solution resulting in, for example, graphene-grafted-poly-FMA and / or similar. The incorporation of carbon-fluorine bonds into the exposed graphene surfaces may enable a Wurtz reaction 350 to occur between the carbon-fluorine bonds and the metallic surface of the alkali metal (e.g., lithium) supplied by the anode 302. Thus, the completion of the Wurtz reaction 350 may result in the formation of a polymer network 330. In some embodiments, the polymer network 330 may include a density gradient 316 following the completion of the Wurtz reaction 350. The density gradient 316 may include interconnected graphene flakes and may be implanted with one or more metal fluoride salts formed in situ. Furthermore, the porosity and / or mechanical properties of the layer may be tuned by combinations of supported and / or functionalized carbons, each having its own and / or distinct physical structure.

[0053] In some embodiments, the carbonaceous material in the density gradient 316 may include one or more of the following: flat graphene, wrinkled graphene, carbon nanotubes (CNTs), or carbon nanoonions (CNOs) in the form of spherical non-hollow structures (e.g., as shown in Figures 4A and 4B). In one embodiment, the graphene nanoplatelets may be dispersed throughout the polymer network 310 and separated from one another. The dispersion of graphene nanoplatelets includes one or more different concentration levels. In one embodiment, the dispersion of graphene nanoplatelets may include at least a portion of the carbonaceous material functionalized by at least a portion of the fluorinated polymer chains.

[0054] For example, the fluorinated polymer chain may contain one or more acrylate or methacrylate monomers, including vinyl monomers such as 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl acrylate (DFHA), 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl methacrylate (HDFDMA), 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate (OFPMA), tetrafluoropropyl methacrylate (TFPM), 3-[3,3,3-trifluoro-2-hydroxy-2-(trifluoromethyl)propyl]bicyclo[2.2.1]hept-2-yl methacrylate (HFA monomer), or 2,3,4,5,6-pentafluorostyrene (PFSt).

[0055] In some embodiments, fluorinated polymer chains are grafted onto the surface of a layer of carbonaceous material, thereby allowing them to chemically interact with one or more surfaces of an alkali metal anode via the Wurtz reaction 350. In organic chemistry, organometallic chemistry, and inorganic main polymers, the Wurtz reaction is a coupling reaction in which two alkyl halides react with a sodium metal (or some other metal) in a dry ether solution to form a higher alkane. In this reaction, alkyl halides are treated with an alkali metal, e.g., sodium metal, in a dry ether (water-free) solution to produce a higher alkane. In the case of a lithium intermediate product of the Wurtz reaction, a highly polar and reactive carbon-lithium metallic bond is formed, which chemically reacts with a halogenated carbon (e.g., fluoride) bond to obtain a newly formed CC bond and lithium fluoride. The formation of the new CC bond makes it possible to use the Wurtz reaction to produce higher alkanes containing an even number of carbon atoms, for example. C-F + 2Li → C-Li + +LiF (Equation 4) C-Li + +CF→C-C+LiF (Formula 5)

[0056] Other metals, particularly silver, zinc, iron, activated copper, indium, and mixtures of manganese and copper chloride, are also used to affect the Wurtz bond. The related reaction involving aryl halides is called the Wurtz-Fittig reaction. This is because of the Friedrich The formation of a dikal intermediate and subsequent disproportionation can be explained by the generation of an alkene. The Wurtz reaction 350 occurs via a free radical mechanism that enables side reactions that produce alkene byproducts. In some embodiments, the chemical interactions associated with the above Wurtz reaction may form alkali metal fluorides, such as lithium fluoride.

[0057] In one embodiment, the polymer network 310 may include an interface layer 318 in contact with the anode 302. The protective layer 320 may be placed on top of the interface layer 318, which may be based on a Wurtz reaction 350 at the interface between the anode 302 and the polymer network 310. The interface layer 318 may have a relatively high crosslinking density (e.g., of a fluorinated polymer and / or similar), a high metal fluoride concentration, and a relatively low carbon-fluorine bond concentration. In contrast to the interface layer 318, the protective layer 320 may have a relatively low crosslinking density, a low metal fluoride concentration, and a high carbon-fluorine bond concentration.

[0058] In some embodiments, the interfacial layer 318 may contain crosslinkable monomers such as methacrylate (MA), acrylate, vinyl functional groups, or combinations of epoxy and amine functional groups. In one embodiment, the protective layer 320 may be characterized by a density gradient 316. Thus, the density gradient 316 may be related to one or more self-healing properties of the protective layer 320 and / or can reinforce the polymer network 310. In some embodiments, the reinforced protective layer 320 may further suppress alkali metal dendrite formation 340 from the anode 302 during battery cycling.

[0059] In terms of operation, the interface layer 318 can suppress alkali metal dendrite formation 340 associated with the anode 302 by uniformly generating metal fluoride, such as lithium fluoride, at the interface along the length of the anode 302. The uniform generation of metal fluoride ultimately suppresses alkali metal dendrite formation 340 by causing, for example, dissolution of the dendrite surface due to conversion to metal fluoride. Furthermore, alkali metal dendrite formation 340 can be further suppressed by crosslinking of fluorinated polymer chains on the remaining dendrites. In some embodiments, the density gradient 316 can be adjusted to control the degree of crosslinking between fluorinated polymer chains.

[0060] Figure 4A shows micrographs 400 of several carbonaceous spherical particles 402 according to several embodiments. In some examples, the carbonaceous spherical particles 402 may be the same as the NHCS particles 226 in Figure 2. Each carbonaceous spherical particle 402 may contain a non-hollow core region with a relatively low carbon density surrounded by various monolithic carbon growths and / or layerings with a relatively high carbon density. The carbonaceous spherical particles 402 may contain multiple concentric multilayer fullerenes and / or similar shaped carbonaceous structures organized at various levels of density and / or concentration. For example, the final shape, size, and graphene composition of each carbonaceous spherical particle 402 may depend on various manufacturing processes. In some embodiments, the carbonaceous spherical particles 402 may exhibit poor water solubility. Therefore, in some embodiments, non-covalent functionalization may be used to alter one or more dispersibility properties of the carbonaceous spherical particles 402 without affecting the intrinsic properties of the underlying carbon nanomaterial. In some embodiments, the underlying carbon nanomaterial may be sp 2 Carbon nanomaterials may be formed. In some embodiments, each of the carbonaceous spherical particles 402 may have a diameter of about 20 to 500 nm. In various embodiments, a group of carbonaceous spherical particles 402 may coalesce and / or aggregate to form a carbonaceous structure 404. In some examples, the carbonaceous structure 404 may be an example of the carbonaceous structure 225 in Figure 2. Furthermore, a group of carbonaceous structures 404 may coalesce and / or bond to form an aggregate 406.

[0061] Figure 4B shows micrographs 450 of carbonaceous structure 460 according to several embodiments. In some examples, carbonaceous structure 460 may be an example of carbonaceous structure 404 in Figure 4A. In some embodiments, the external carbonaceous shell-type structures 442, 444, and 446 may fuse to form a carbonaceous structure 460. The group of carbonaceous structures 460 may accrete and / or join to form an aggregate 406 in Figure 4A. In some embodiments, the core region 448 of each carbonaceous shell-type structure 446 may be adjustable, for example, in that the core region 448 may contain various defined concentration levels of interconnected graphene structures. In some embodiments, each carbonaceous shell-type structure 446 may have a first concentration of interconnected carbon of about 0.1 g / cc to 2.3 g / cc in or near each carbonaceous shell-type structure 446. Each carbonaceous shell-type structure may have pores for transporting lithium ions that extend inward toward the core region 448.

[0062] In some embodiments, the pores of the carbonaceous shell-type structures 442, 444, and 446 may have widths or dimensions of approximately 0.0 nm to 0.5 nm, approximately 0.0 to 0.1 nm, approximately 0.0 to 6.0 nm, or approximately 0.0 to 35 nm. Each of the carbonaceous shell-type structures 442, 444, and 446 may also have a second concentration different from the first concentration in or near the core region 448. For example, the second concentration may include a plurality of relatively low-density carbonaceous regions arranged concentrically. In one embodiment, the second concentration may be lower than the first concentration, in the range of approximately 0.0 g / cc to 1.0 g / cc or approximately 1.0 g / cc to 1.5 g / cc. In some embodiments, the relationship between the first and second concentrations may be used to maximize lithium ion transport and gaseous oxygen uptake while simultaneously providing a suitable retention location for lithium oxide.

[0063] In some embodiments, at least a portion of the carbonaceous shell-type structures 442, 444, and 446 may contain carbon nanoonion (CNO) oxides organized as monolithic growth and / or interconnected growth and produced in a thermal reactor. In one embodiment, the carbonaceous shell-type structures 442, 444, and 446 may be decorated with cobalt nanoparticles according to the following example recipe: cobalt(II) acetate (C4H6CoO4), which is the cobalt salt of acetate (often found as the tetrahydrate Co(CH3CO2)24H2O, sometimes abbreviated as Co(OAc)2·4H2O), is poured into a thermal reactor at a ratio of about 59.60 wt% corresponding to 40.40 wt% carbon (referring to carbon in the form of CNO), thereby allowing the active sites of the CNO oxide to be functionalized with cobalt. In some embodiments, a suitable gas mixture used for the production of cobalt-decorated CNO may include the following steps. • 30 minutes of Ar purging at 0.75 standard cubic feet / minute (scfm); • Ar purge changed to 0.25scfm for execution; • A temperature increase from 25°C to 300°C in 20 minutes; and • Temperature increase from 300°C to 500°C in 15 minutes; It may include

[0064] The carbonaceous materials described with reference to Figures 4A and 4B may include one or more examples of graphene, or may be formed from one or more examples of graphene in other ways, which may include monolayers of carbon atoms in which each atom is bonded to three adjacent atoms within a honeycomb structure. This monolayer may be a one-dimensionally constrained discrete material, such as within or on the surface of a condensed phase. For example, graphene may grow outward only in the x and y planes (but not the z plane). Thus, graphene may be a two-dimensional (2D) material containing one or more layers in which the atoms of each layer are strongly bonded to adjacent atoms in the same layer (by multiple carbon-carbon bonds, for example).

[0065] In some embodiments, the graphene nanoplatelets (e.g., the formed structures included in carbonaceous shell-type structures 442, 444, and 446, respectively) are decorative and inherent. To form the 3D carbonaceous structure, the graphene may include multiple examples of graphene, such as a first graphene layer, a second graphene layer, and a third graphene layer, all stacked vertically on top of each other. Each of the graphene nanoplatelets, which may be called GNPs, may have a thickness of 1 nm to 3 nm and a lateral dimension in the range of about 100 nm to 100 μm. In some embodiments, the graphene nanoplatelets may be produced by roll-to-roll (R2R) production using multiple plasma spray torches arranged in a continuous line. In some embodiments, R2R production may include deposition onto a continuous substrate which is processed as a rolled sheet, including the transfer of 2D material(s) onto separate substrates. The plasma spray torches used in the R2R process may spray carbonaceous material at different concentration levels to produce specific concentration levels of graphene nanoplatelets, thereby providing fine-level tunability for cathode 110 in Figure 1 and / or cathode 200 in Figure 2.

[0066] Figure 5A shows SEM micrographs 500A of graphene powder according to several embodiments. The adjacent graphene sheets and / or layers in micrograph 500A have a complex 3D structure to prevent graphene re-layering, which can avoid some of the drawbacks of using 2D graphene.

[0067] Figure 5B shows SEM micrographs 500B of nodular carbon produced by a thermal process according to several embodiments. The nodular carbon shown in micrograph 500B can be used to generate NHS particles 222 in the cathode 110 in Figure 1 and / or Figure 2. Thus, the nodular carbon in micrograph 500B can create a unique double-pore system that can simultaneously retain lithium oxide while facilitating the free passage of gaseous oxygen into the internal region of the cathode 110 when necessary for optimal lithium-air battery operation. The nodular carbon shown in micrograph 500B may be characterized by pores, each having a diameter between approximately 0.6 nanometers (nm) and 6.6 nm, thereby enabling the retention of lithium oxide within these pores.

[0068] Figure 5C shows SEM micrographs 500C of carbon treated with carbon dioxide (CO2) according to several embodiments. The 3D graphene-formed and / or carbonaceous material shown in micrograph 500C can be produced by CO2 treatment and may be used to generate the cathode 110 in Figure 1 and / or the NHS particles 222 in Figure 2 of the battery 100 in Figure 1.

[0069] Figure 5D shows SEM micrographs 500D of carbon treated with carbon dioxide (CO2) according to several embodiments. The 3D graphenized and / or carbonaceous material shown in micrograph 500C is produced by CO2 treatment and can be used to produce the cathode 110 in Figure 1 of the battery 100 in Figure 1 and / or the NHCS particles 226 in Figure 2.

[0070] Figure 6 shows micrographs 600 of three-dimensional (3D) graphene after carbon dioxide (CO2) treatment according to several embodiments. In some examples, the treated 3D graphene can be used to generate NHCS particles 226 for the cathodes 110 of lithium-air batteries 100 and 200, respectively, as shown in Figures 1 and 2.

[0071] Figure 7 shows Graph 700 illustrating the exemplary distribution of pore volume as a function of pore width in graphenized nanosheets of NHCS particles 226 of cathode 110 in Figure 2 or other carbonaceous materials described herein, according to several embodiments. As shown in Graph 700, pores associated with relatively high pore volumes may have relatively low pore widths, for example, such that the pore width generally increases as the pore volume decreases. In some embodiments, pores with a pore width of less than about 1.0 nm may be referred to as micropores, pores with a pore width of about 3 to 11 nm may be referred to as mesopores, and pores larger than about 24 nm may be referred to as mesopores. Pores that have a pore width are sometimes referred to as macropores.

[0072] See also Figure 1, the lithium-air battery 100 can be activated by allowing oxygen supplied from ambient air 170 to enter the interior of the lithium-air battery 100 through various pores 112 and pathways 114 formed in the cathode 110. As already mentioned, the oxygen supplied to the lithium-air battery 100 reacts with lithium supplied by the anode 120 to produce lithium ions and free electrons at or near the anode 120. The lithium ions move from the anode 120 to the cathode 110 through the electrolyte 130 and react with oxygen at or near the cathode 110 to produce lithium oxide. The free electrons move from the anode 120 to the cathode 110 through the external circuit, thereby generating an electric current through the external circuit. During the battery charging cycle, oxygen supplied from ambient air 170 donates electrons to the lithium oxide present at or near the cathode 110 to produce lithium ions and electrons. The electrochemical potential between the anode 120 and the cathode 110 causes lithium ions to return to the anode 120, and these returning lithium ions accumulate, allowing lithium to be plated onto the anode 120.

[0073] As illustrated with reference to Figure 2, lithium oxide (and other undesirable by-products) generated during the operation of the battery 100 can clog the openings of pores 210a-210b, which are involved in delivering oxygen from the ambient air 170 to the interior of the battery 100. In some embodiments, the width or diameter of the openings of pores 210a-210b may be increased to reduce the likelihood of blockage by lithium oxide (and other undesirable by-products). However, aspects of the present disclosure also recognize that increasing the width or diameter of the pore openings may unintentionally allow water droplets and / or water vapor to enter the cathode 110 through pores 112 and pathway 114, as illustrated with reference to Figure 1. Furthermore, the hydrophilicity of at least a portion of the carbonaceous structures 225 that define the transport pores 210 and transport pathways 220 within the cathode 110 allows these carbonaceous structures 225 to attract or retain water vapor associated with various chemical reactions within the battery 100. However, the hydrophilicity of these carbonaceous structures 225 may allow water droplets to accumulate on the surface of these carbonaceous structures 225. In some cases, the accumulated water droplets can enter the pore pathways 114 formed within the cathode 110, diffuse through at least some portions of the cathode 110, and react with lithium in the battery in undesirable ways. This phenomenon, commonly referred to as "flooding," can not only reduce the specific capacity of the battery 100 but may also shorten the battery's lifespan.

[0074] Figure 8A shows an example 800 illustrating water droplets formed or placed on the outer surface of a multi-layer graphene (FLG) 810. The FLG 810 may contain 3 to 15 layers of carbon atoms and can be used to form a carbonaceous structure 225 that defines various pores 210 and pathways 220 formed within the cathode 110 of the battery 100 in Figure 1. Specifically, several examples of FLG 810 (and / or porous non-hollow carbonaceous spherical (NHCS) particles 226 described with reference to Figure 2) can coalesce to form aggregates of carbonaceous material that define the shape, size and / or orientation of the pores 210 and pathways 220 formed throughout the cathode 110. A first pore 811 having a first diameter (d1) is formed on the upper surface 801 of the FLG 810 and may be in fluid communication with one or more pathways and / or cavities (not shown for simplicity) formed throughout the FLG 810. A second pore 812 having a second diameter (d2) is formed in the lower surface 802 of the FLG 810 and may be in fluid communication with one or more paths and / or cavities (not shown for simplicity) formed throughout the FLG 810. The first pore and the second pores 811 and 812 may be separated by a pore spacing distance. In some embodiments, for example, the first diameter d1 is greater than the second diameter d2 such that the opening of the first pore 811 is wider than the opening of the second pore 812.

[0075] In the example shown in Figure 8A, a first water droplet 821 is formed or positioned on the upper surface 801 of the FLG810, and a plurality of second water droplets 822 are formed or positioned on the lower surface 802 of the FLG810. For the sole purpose of illustrating the tunability of the FLG810, the upper part of the FLG810 may be tuned to exhibit hydrophobic properties, and the lower part of the FLG810 may be tuned to exhibit hydrophilic properties. The hydrophobic properties of the upper part of the FLG810 can prevent the water droplet 821 from moving along the upper surface 801 of the FLG810 and entering the first pore 811. On the other hand, the hydrophilic properties of the lower part of the FLG810 can prevent the plurality of water droplets 8 2It may be possible for 2 to form a continuous water film along the lower surface 802 of FLG 810. In some examples, the continuous film of water droplets 822 may be in equilibrium due to cohesive forces within the water film and adhesive forces between the water droplets and the FLG surface. As illustrated, the surface tension of the continuous film of water droplets 822 may prevent the water droplets 822 from entering the second pore 812, at least in part due to the relatively small diameter d2 of the second pore 812 (compared to, for example, the relatively large diameter d1 of the first pore 811).

[0076] Figure 8B shows an example 850 illustrating exemplary flooding (not shown for simplicity) of a lithium-air battery, including a cathode at least partially formed by the FLG 810 described with reference to Figure 8A. As discussed with reference to Figure 8A, the first pore 811 has a relatively large pore opening (indicated by a first diameter d1), and the second pore 812 has a relatively small pore opening (indicated by a second diameter d2, where d1 > d2). In some examples, the relatively large opening of the first pore 811 may allow water droplets 821 collected on the upper surface 801 of the FLG 810 to enter the interior portion of the first pore 811, causing them to flood. Similarly, the larger diameter d2 of the second pore 812 in the example of Figure 8B may allow some of the water droplets 822 in the continuous film to enter the interior portion of the second pore 812, causing them to flood.

[0077] In some embodiments, the FLG810 (and other carbon-based structures) defining various pores 210 and pathways 220 throughout the cathode 110 can be tuned in such a way that lithium can be deposited in pores and / or cavities formed within the FLG801, which are less susceptible to flooding. Specifically, in some examples, the FLG810 may be tuned such that the diameters of the first pore 811(d1) and the second pore 812(d2) are both small enough to prevent flooding of the respective first and second pores 811 and 812.

[0078] Figure 9A shows an example 900 illustrating the charged state of a lithium-air battery. In some embodiments, FLG810 may be used to form at least a portion of the cathode of a lithium-air battery. More specifically, FLG810 may be a constituent unit for a carbonaceous structure defining various pores 210 and pathways 220 within the cathode 110 of battery 100 in Figure 1. As already mentioned, FLG810 (and / or other carbonaceous materials, particularly porous NHCS particles 226 or CNO particles in Figure 2, among other examples) may coalesce with each other to form aggregates of carbonaceous material throughout the cathode 110 that define the shape, size, and / or orientation of the pores 210 and pathways 220.

[0079] FLG810 has pores 910 containing several Li2O crystals 912 and hexagonal LiO x The crystal 914 and three water droplets 921-923 collected on the upper surface 801 of the FLG 810 are included. Each of the three droplets 921-923 is positioned at a corresponding first angle (θ1) with respect to the upper surface 801 of the FLG 810. The middle droplet 922 is positioned above the pore 910 at a second angle (θ2) with respect to the upper surface 801 of the FLG 810, and the pore 910 has a diameter (d2). In various embodiments, the diameter d2 of the pore 910 may be small enough to prevent water from entering or accumulating within the pore 910.

[0080] Hexagonal LiO x Crystal 914 is hexagonal LiO x The crystal 914 is positioned at a distance of a first distance (L1) from the wall of the pore 910 so that it does not come into contact with the carbon material inside the pore 910. In some examples, the first distance (L1) is the electron tunneling distance (therefore, electrons generated during the oxidation reaction (e) -) is smaller than (it is possible to tunnel through FLG810 to pore 910). The resulting transfer of electrons to pore 910 allows the electrons to react with Li2O912 to convert Li2O912 into lithium metal, thereby providing an active material for the operation of the associated lithium-air battery. In this way, a stoichiometric Li2O crystal (such as Li2O crystal 912) electrochemically connected to graphene can react with electrons to form lithium metal. In some embodiments, pore 910 may be considered hydrophilic when the angle θ2 is greater than 90 degrees, and pore 910 may be considered hydrophobic when the angle θ2 is less than 90 degrees.

[0081] Figure 9B shows an example illustrating the discharge state of a lithium-air battery. In some embodiments, FLG810 can be used to form at least a portion of the cathode of a lithium-air battery. More specifically, FLG810 can be used to form a carbonaceous structure that defines various pores 210 and pathways 220 formed in the cathode 110 of battery 100 in Figure 1. As described, various porous non-hollow carbonaceous spherical (NHCS) particles 226 described with reference to FLG810 and / or Figure 2 can coalesce to form aggregates of carbonaceous material that define the shape, size, and / or orientation of the pores 210 and pathways 220 throughout the cathode 110.

[0082] FLG810 is Li2O crystal 912, hexagonal LiO x The crystal 914 and the pore 910 containing three water droplets 921-923 as described with reference to Figure 9A are shown. In the example in Figure 9B, hexagonal LiO x Crystal 914 is a hexagonal LiO crystal as shown in Figure 9A. x It is rotated relative to crystal 914 and positioned at a distance (L2) from the wall of pore 910, in which case distance L2 is greater than distance L1 in Figure 9A. Specifically, hexagonal LiO in Figure 9B x Due to the arrangement of crystal 914, the distance L2 becomes greater than the electron tunneling distance, causing electrons to tunnel through FLG810 into pore 910, resulting in hexagonal LiOx This may prevent the reaction with crystal 914. In this way, non-stoichiometric LiO x Crystal (LiO x Crystals (such as 914) are formed when, for example, electrons tunnel through pores 910, resulting in non-stoichiometric LiO x Since it cannot react with the crystal, it is not converted to lithium metal. In some embodiments, the pores 910 may be considered hydrophilic when the angle θ2 is greater than 90 degrees, and the pores 910 may be considered hydrophobic when the angle θ2 is less than 90 degrees.

[0083] Figure 10 shows an example 1000 illustrating various types of FLGs. Specifically, in example 1000, FLG model 1010 is shown as a flat sheet, and a curved FLG 1020 is shown as an arched surface. Example 1000 also shows multilayer fullerene 1030 as spherical CNO particles with internal pores not exposed to ambient air, which can prevent the multilayer fullerene 1030 from reacting with oxygen (or water) provided by the ambient air. Example 1000 also shows treated CNO particles 1040 having tuned or configured pore openings 1042 through which ambient air can enter and diffuse throughout the cathode formed by the treated CNO particles 1040.

[0084] Figure 11 illustrates carbonaceous aggregates 1100 according to several embodiments. The carbonaceous aggregate 1100 contains a plurality of CNO particles 1110 and 1120 (only two CNO particles 1110-1120 are shown for simplification). In some examples, the carbonaceous aggregate 1100 may be an example of the carbonaceous structure 225 described with reference to Figure 2. Each of the CNO particles 1110 and 1120 has an opening 1 The particles 111 and 1121 may be processed and adjusted to achieve a desired width. As shown in the figure, oxygen (O2) supplied by the ambient air can enter the interior of the carbonaceous aggregate 1100 through the walls of the carbonaceous aggregate 1100. In some embodiments, the CNO particles 1110 and 1120 can be adjusted to exhibit hydrophobic properties that can repel water droplets (H2O), such as water vapor or water droplets, from entering the interior of the carbonaceous aggregate 1100. In some embodiments, the hydrophobic adjusted CNO particles 1110 and 1120 can retain water in various transport pathways between the CNO particles 1110-1120 (not shown for simplicity). Adjusting the CNO particles 1110 and 1120 to exhibit hydrophobic properties in this way can prevent water from entering the battery through the pore openings and reacting with lithium (which is undesirable).

[0085] In some examples, each of the CNO particles 1110 and 1120 may have a radius of about 5 nm to 25 nm. In other examples, the radii of the CNO particles 1110 and 1120 may be about 5 nm to 50 nm. In some other examples, the radii of the CNO particles 1110 and 1120 may be between about 3 nm and 500 nm. The aspects of the subject disclosed herein recognize that when the radius of each CNO particle is less than about 100 nm, a single cavity may be formed during the formation of each CNO particle. The formation and adjustment of a single cavity within the CNO particles 1110 and 1120 may have the advantage of being relatively easy to control (compared to the formation and adjustment of multiple cavities). On the other hand, when the radius of each CNO particle reaches or exceeds about 100 nm, multiple cavities may be formed during the formation of each CNO particle. Multiple cavities within CNO particles can make the pathways formed within the CNO particles (e.g., pathway 220 as described in Figure 2) more meandering than pathways formed within CNO particles with a single cavity. In addition, providing multiple cavities within CNO particles can increase the amount of lithium that can be stored within the cavities of the CNO particles, thereby increasing the specific capacity of the associated lithium-air battery.

[0086] For example, as shown in Figure 11, the first CNO particle 1110 has a radius R1 of less than approximately 100 nm, and the second CNO particle 1120 has a radius R2 of greater than approximately 100 nm. Thus, the first CNO particle 1110 may include a single cavity (not shown for simplicity) associated with a relatively less meandering path 1113 between the opening 1111 of the first CNO particle 1110 and the core 1112, and the second CNO particle 1120 may include multiple cavities (not shown for simplicity) associated with a relatively more meandering path 1123 between the opening 1121 of the second CNO particle 1120 and the core 1122. The relatively less meandering path 1113 formed in the first CNO particle 1110 allows oxygen supplied by the ambient air to propagate through the CNO particle 1110 toward the core 1112. However, the relatively less meandering pathway 1113 also allows water (such as water droplets or water vapor) to enter the interior of the first CNO particle 1110, which, as mentioned above, could lead to flooding of the associated lithium-air battery (such as lithium-air battery 100 in Figure 1).

[0087] Conversely, the relatively meandering pathways 1123 formed in the second CNO particle 1120 may prevent water droplets from entering the interior of the second CNO particle 1120 (for example, due to an increased travel distance between the pore opening 1121 and the core 1122 through the relatively meandering pathways 1123), thereby preventing flooding of the associated lithium-air battery. However, the relatively meandering pathways 1123 may also limit or suppress oxygen supplied by the ambient air from flowing through the second CNO particle 1120 and diffusing throughout the corresponding anode, which, as mentioned above, may reduce the specific capacity of the associated lithium-air battery.

[0088] Aspects of the subject matter disclosed herein relate to the optimal performance of lithium-air batteries, It is recognized that achieving a desired balance may involve enabling sufficient oxygen to propagate into the CNO particles forming the cathode of the battery and preventing (or at least suppressing) the propagation of water into such CNO particles. In some embodiments, this desired balance can be achieved by selectively tuning the carbonaceous material in the cathode of the lithium-air battery (such as the CNO particles 1110 and 1120 in Figure 11) to exhibit a certain level of hydrophilic behavior or a certain level of hydrophobic behavior. In some examples, these carbonaceous materials can be tuned to allow lithium to react in various cavities of the CNO particles that are less susceptible to flooding.

[0089] Specifically, in various embodiments, the CNO particles 1110 and 1120 (and other carbonaceous materials or structures) may be etched to configure the width or diameter of their respective pore openings 1111 and 1121 to be less than a critical dimension associated with preventing water droplets from entering each path 1113 and 1123. In some examples, as described with reference to Figure 8A, at least some exposed surfaces of the CNO particles in the cathode may be tuned to exhibit hydrophobic properties that can prevent water droplets from moving along the cathode surface or towards nearby pore openings of the CNO particles. In addition, or alternatively, as described with reference to Figure 8A, the exposed surfaces of some other CNO particles in the cathode may be tuned to exhibit hydrophilic properties that allow the formation of a continuous water film with sufficient surface tension to prevent arranged water droplets from entering the pore openings and flooding the lithium-air battery. In some examples, multiple CNO particles (and / or other carbonaceous materials or structures) forming the cathode can be selectively etched to create winding transport pathways (such as the winding pathway 1123 formed in CNO particle 1120) that allow oxygen supplied by the ambient air to penetrate and diffuse throughout the cathode, while simultaneously suppressing the propagation of water droplets within or throughout the cathode.

[0090] As already mentioned, groups of CNO particles (such as CNO particles 1110 and 1120) or porous non-hollow carbonaceous spherical particles can coalesce to form larger carbonaceous structures that define various pores, pathways, and cavities within the cathode of a lithium-air battery. In various embodiments, the size and porosity of these relatively large carbonaceous structures can be controlled and / or tuned to ensure a certain level of meandering of the pathways and / or to ensure that the openings of their respective pores are smaller than critical dimensions. In this way, the hierarchical pore structure, configured porosity, and tuned behavior of CNO particles 1110 and 1120 (and / or other carbonaceous materials) used in the cathode of a lithium-air battery can prevent water from entering the pore openings and causing the lithium-air battery to flood, while at the same time allowing a sufficient amount of oxygen supplied by the ambient air to propagate through the various pores and pathways of the cathode and participate in the chemical reactions related to the generation of the output current (or voltage) of the lithium-air battery. Furthermore, by increasing the degree to which the lithium-air battery can prevent water droplets from entering and spreading throughout the cathode, embodiments of the subject disclosed herein can extend the shelf life of the lithium-air battery by preventing, for example, inadvertent activation of the lithium-air battery caused by exposure to rain, sprinklers, or other sources of water droplets.

[0091] When used herein, expressions referring to “at least one” or “one or more” in a list of items refer to any combination of those items that include a single member. “At least one of a, b, or c” is intended to cover the possibilities of a only, b only, c only, a and b combination, a and c combination, b and c combination, and a, b, and c combination.

[0092] This specification includes structures and their structural equivalents. The various exemplary components, logic circuits, logic blocks, modules, circuits, operations, and algorithmic processes described in relation to the embodiments may be executed as electronic hardware, firmware, software, or a combination of hardware, firmware, or software. Hardware, firmware, and software compatibility is generally described in terms of functionality, as illustrated in the various exemplary components, blocks, modules, and processes described above. Whether such functionality is executed in hardware, firmware, or software depends on the application and the design constraints imposed on the overall system.

[0093] Various modifications to the embodiments described herein may be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the spirit or scope of this disclosure. Accordingly, the claims are not intended to be limited to the embodiments shown herein, but the broadest scope that is consistent with this disclosure, the principles disclosed herein, and novel features is permitted.

[0094] Furthermore, various features described herein in the context of separate embodiments may be implemented in combination in a single embodiment. Furthermore, various features described in the context of a single embodiment may be implemented separately or in preferred partial combinations in multiple embodiments. Thus, features may be described above in combination with one another, and may even be initially claimed to be so, but one or more features from the claimed combination may, in some cases, be extracted from the combination, and the claimed combination may be a partial combination or a variation of a partial combination.

[0095] Similarly, while operations are shown in a specific order in the diagrams, this should not be understood as requiring that such operations be performed in a specific or sequential order shown, or that all illustrated operations be performed, in order to achieve the desired result. Furthermore, the diagrams may schematically illustrate another exemplary process in the form of a flowchart or flow diagram. However, other operations not illustrated can be incorporated into the exemplary process that is schematically described. For example, one or more additional operations can be performed before, after, simultaneously with, or in between the operations shown in the diagrams. Depending on the circumstances, multitasking and parallel processing may be advantageous. Furthermore, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single product or encompassed in multiple products.

Claims

1. It is a metal-air battery, A carbonaceous cathode comprising one or more cathode surfaces exposed to ambient air, wherein the one or more cathode surfaces contain a catalyst, An anode positioned opposite the cathode, A first electrolyte disposed between the anode and the cathode, An inorganic passivation layer formed as a film in contact with the anode, An outer layer disposed on the passivation layer, wherein the outer layer comprises one or more solid second electrolytes encapsulated in an ion-conducting salt or polymer. Includes, A metal-air battery in which the anode contains one or more of lithium, sodium, zinc, indium, or gallium.

2. The inorganic passivation layer is lithium fluoride (LiF) or lithium oxide (Li ２ A metal-air battery according to claim 1, comprising one or more of the following:

3. The metal-air battery according to claim 1, wherein the solid second electrolyte comprises lithium lanthanum zirconium oxide.

4. The metal-air battery according to claim 1, further comprising a separator disposed between the anode and the cathode.

5. The metal-air battery according to claim 4, wherein the separator includes a ceramic-containing material that does not react with metallic lithium.

6. The metal-air battery according to claim 1, wherein the catalyst comprises one or more of manganese, nickel oxide, cobalt, ruthenium, platinum, silver, gold, or a mixture thereof.

7. The metal-air battery according to claim 1, wherein the catalyst comprises one or more compounds selected from manganese, nickel oxide, cobalt, ruthenium, platinum, silver, or mixtures thereof.

8. The metal-air battery according to claim 1, wherein the carbonaceous cathode includes a three-dimensional (3D) graphene structure formed from a stack of graphene nanosheets.

9. The metal-air battery according to claim 8, wherein each graphene nanosheet in the stack of graphene nanosheets has a major dimension of less than 1 μm.

10. The metal-air battery according to claim 8, wherein at least one graphene nanosheet in the stack of graphene nanosheets comprises a plurality of mesopores.

11. The cathode is 5m ２ / g and 3,000m ２ The metal-air battery according to claim 1, having a surface area in an approximate range between / g.

12. The metal-air battery according to claim 1, wherein the cathode comprises graphene doped with one or more nitrogen or sulfur.

13. The metal-air battery according to claim 1, wherein the first electrolyte comprises one or more of aprotic liquid electrolytes, solid polymer electrolytes, or gel polymer electrolytes.

14. The metal-air battery according to claim 1, wherein the first electrolyte comprises a non-aqueous organic solvent.

15. The metal-air battery according to claim 1, wherein the first electrolyte comprises an organic solvent containing an ether-based solvent.

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