阅读说明：本技术 电池 (Battery with a battery cell ) 是由 汉述仁 D·B·法梅 D·吴 H·T·莫内 C·埃克根 E·埃克卡 G·德米西 于 2018-06-13 设计创作，主要内容包括：电池及其形成方法包括锂阳极、对锂离子和氧具有高溶解度的电解质以及在衬底上形成的薄石墨烯阴极。锂离子从锂阳极穿过电解质迁移,从而在薄石墨烯阴极的表面形成Li2O2。(A battery and method of forming the same includes a lithium anode, an electrolyte having high solubility for lithium ions and oxygen, and a thin graphene cathode formed on a substrate. Lithium ions migrate from the lithium anode through the electrolyte, forming Li2O2 at the surface of the thin graphene cathode.)

1. A battery, comprising:

a lithium anode;

an electrolyte having high solubility for lithium ions and oxygen; and

a thin graphene cathode formed on a substrate such that lithium ions migrate from the lithium anode through the electrolyte to form Li at the surface of the thin graphene cathode₂O₂。

2. The battery of claim 1, wherein the thin graphene cathode is a material selected from the group consisting of single-layer graphene and double-layer graphene.

3. The battery of claim 1, wherein the electrolyte comprises 1, 2-dimethoxyethane.

4. The battery of claim 1, wherein the electrolyte comprises tetraglyme.

5. The battery of claim 1, wherein the electrolyte comprises a material selected from the group consisting of LiNO₃And (lithium bis (trifluoromethanesulfonyl) imide).

6. The battery of claim 1, further comprising a current collector positioned between the cathode and a separator or between the cathode and the electrolyte.

7. The battery of claim 6, wherein the current collector is a metal mesh formed from a material selected from stainless steel and titanium, and wherein the metal mesh has openings of less than about 38 μm.

8. The battery of claim 1, further comprising:

a current collector in the electrolyte formed by a metal mesh; wherein the thin graphene cathode is formed from a single or double layer graphene material.

9. The battery of claim 8, wherein the electrolyte is selected from the group consisting of 1, 2-dimethoxyethane and tetraglyme.

10. The battery of claim 9, wherein the electrolyte comprises a material selected from LiNO₃And (lithium bis (trifluoromethanesulfonyl) imide).

11. A method of forming a battery comprising:

forming a thin graphene cathode on a substrate;

providing a lithium anode; and

an electrolyte is provided between the thin graphene cathode and the lithium anode.

12. The method of claim 11, wherein the thin graphene cathode is a layer selected from the group consisting of single-layer graphene and double-layer graphene.

13. The method of claim 11, wherein the electrolyte comprises 1, 2-dimethoxyethane.

14. The method of claim 11, wherein the battery comprises tetraglyme.

15. The method of claim 11, wherein the electrolyte comprises a material selected from LiNO₃And (lithium bis (trifluoromethanesulfonyl) imide).

16. The method of claim 11, further comprising providing a current collector in the electrolyte.

17. The method of claim 16, wherein the current collector is a metal mesh formed from a material selected from the group consisting of stainless steel and titanium, and wherein the metal mesh has openings of less than about 38 μ ι η.

18. The method of claim 11, wherein forming the thin graphene cathode comprises:

depositing a thin graphene layer on the initial surface;

transferring the thin graphene layer from the initial surface to the intermediate surface; and

the thin graphene layer is transferred from the intermediate surface to the substrate.

19. The method of claim 18, further comprising: patterning the thin graphene layer after transferring the thin graphene layer onto the intermediate surface using the intermediate surface as a mask.

20. The method of claim 18, wherein the initial surface is formed of copper, and wherein the intermediate surface is formed of a material selected from the group consisting of poly (methyl methacrylate) and ethylene vinyl acetate.

Technical Field

The present invention relates generally to batteries, and more particularly to the use of thin carbon cathodes in lithium-oxygen batteries.

Background

Lithium ion batteries are common in areas such as consumer electronics, automotive, medical devices and home energy storage. In the lithium ion insertion reaction, the amount of lithium ions that can be inserted into the host cathode determines the energy stored in the battery. As a result, a large cathode is required to increase the storage capacity of the battery. Thus, limitations on how small an effective lithium ion battery can be made while providing useful energy density.

Lithium-oxygen battery chemistries have higher gravimetric and volumetric energy densities than one of the most commonly used cathode materials (e.g., about 3,213Wh/kg and about 7,422Wh/L, respectively, relative to cathode mass or volume only). LiCoO₂(e.g., about 1,095Wh/kg and about 5,543Wh/L, respectively, relative to cathode mass or volume only). Thus, lithium-oxygen batteries provide a way to further miniaturize, thereby reducing the weight and volume of the battery without sacrificing energy capacity. However, existing lithium-oxygen battery embodiments use large porous cathodes, which still have volumetric disadvantages for miniaturized applications.

Disclosure of Invention

The battery includes a lithium anode, an electrolyte having high solubility for lithium ions and oxygen, and a thin graphene cathode formed on a substrate. Lithium ions migrate from the lithium anode through the electrolyte to be thinSurface formation of Li on graphene cathodes₂O₂。

The battery includes: the lithium-ion battery includes a lithium anode, an electrolyte with high solubility for lithium ions and oxygen, a current collector in the electrolyte formed from a metal mesh, and a thin graphene cathode formed from a single-or double-layer graphene material on a substrate. Lithium ions migrate from the lithium anode through the electrolyte, forming Li on the surface of the thin graphene cathode₂O₂。

A method of forming a battery includes forming a thin graphene cathode on a substrate. A lithium anode is provided, and an electrolyte is provided between the thin graphene cathode and the lithium anode.

These and other features and advantages will become apparent from the following detailed description of exemplary embodiments, which is to be read in connection with the accompanying drawings.

Drawings

The following description will provide details of preferred embodiments with reference to the following drawings, in which:

fig. 1 is a cross-sectional view of a lithium-oxygen battery having a thin graphene cathode according to an embodiment of the present invention.

Fig. 2 is a block/flow diagram of a method of forming a lithium-oxygen battery with a thin graphene cathode formed in accordance with an embodiment of the present invention; and

fig. 3 is a graph illustrating the effect of using a thin graphene cathode in a lithium-oxygen battery compared to using a bare substrate according to an embodiment of the present invention.

Detailed Description

Embodiments of the present invention employ a thin cathode layer formed of, for example, graphene having a thickness of a few atoms to form a lithium-oxygen battery to serve as a nucleation seed for a solution-mediated lithium-oxygen battery discharge reaction. Thus, the present embodiment provides greater than about 0.05mAh/cm²With a similar volume of LiCoO₂With Li₂O₂Obtained LiCoO₂Twice the cathode capacity of (a). Embodiments of the invention also provide a gravimetric energy density per cathode mass when including the weight of the discharge product, which is LiCoO₂2000 times of the mass of each cathode, four times of the mass of each cathode.

Referring now to fig. 1, a cross-sectional view of a lithium-oxygen battery 100 is shown. The anode 102 is separated from the cathode 108 by an electrolyte 104 and a separator 106. The electrolyte 104 provides an electrically conductive path for carriers to move from the anode 102 to the cathode 108 during the discharge reaction. Separator 106 is a non-conductive porous structure that prevents anode 102 and cathode 108 from making electrical contact with each other. In some embodiments, the electrolyte 104 is a fluid. In other embodiments, the electrolyte 104 is a solid material that also functions as the separator 106. Cathode 108 is formed on substrate layer 110, which substrate layer 110 may be flexible or rigid, conductive or non-conductive, flat or rough, i.e., for transferring cathode 108.

In one particular embodiment, the anode 102 is formed from a layer of lithium metal, but it should be understood that other materials, such as sodium or other alkali metals, may alternatively be used. In one particular embodiment, the cathode 108 is formed from graphene, which is a very thin carbon substance that can be formed to a thickness of a single atom. In a particular embodiment, the baffle 106 may be a porous polymer film, such as polyethylene or polypropylene or quartz (SiO)₂) A microfiber filter, and may be formed at a thickness of between about 25 μm to 450 μm. In embodiments having mechanical strength, the solid-state electrolyte (which may serve as a separator) 104 may be as thin as a few hundred nanometers. In a particular embodiment, the substrate 110 may be formed from, for example, a silicon or silicon dioxide wafer, a stainless steel pad, glass, or a polyimide film.

In a particular embodiment, the electrolyte 104 is formed of a suitable liquid electrolyte material, for example, with LiNO₃Or lithium (bis (trifluoromethanesulfonyl) imide) (LiTFSI) as a salt and a 1, 2-mixed solution of Dimethoxyethane (DME) or Tetraglyme (TEGDME) as a solvent. The electrolyte enhances battery capacity in single and double layer graphene cathodes, and in forming Li₂O₂With intermediate substances (e.g. Li) in between⁺And O₂ ^-) High solubility of (2). Because the intermediate species may dissolve into the electrolyte during discharge, these species may migrate farther to form larger Li₂O₂Particles other thanThe precipitate forms a film and passivates the cathode surface. Such an electrolyte may further contain a small amount of water.

The current collector 107 is located in the electrolyte 104 and, in some embodiments, may be formed of stainless steel or titanium. It is specifically contemplated that the current collector 107 may be formed from, for example, a wire mesh formed from any suitable metal or other conductor that will not react with or otherwise corrode the electrolyte 104. The current collector 107 may include a mesh having openings less than about 38 μm. This size is only an example, and a finer grid will provide better electron distribution. Current collector 107 exits battery 100 for connection to an external circuit.

It should be understood that embodiments of the present invention illustrate only one possible example of the use of a thin carbon cathode in a battery. It is specifically contemplated that in this embodiment, the cathode 108 may be formed on the copper layer by, for example, Chemical Vapor Deposition (CVD) or any other suitable mechanism. For example, a graphene layer may be formed on a copper layer by carbon CVD, in which carbon atoms are self-organized into a flat plate one or more atoms thick.

Some embodiments may employ a copper layer directly as the substrate 110. However, experimental evidence indicates that graphene/copper electrodes exhibit Li₂O₂Up to 2.1V and then electrochemically reacted with copper at a potential below 2.1V. Thus, the present embodiment transfers graphene to an alternative substrate material. Thus, the cathode 108 may be mounted to an intermediate handle layer formed of, for example, poly (methyl methacrylate) (PMMA), Ethylene Vinyl Acetate (EVA), or any other suitable material having etch selectivity to a copper layer. Then using e.g. FeCl₃The copper layer is etched away, allowing cathode 108 to move to substrate layer 110. The handle layer is then etched away using, for example, acetone for PMMA or xylene for EVA. Cathode 108 may be secured to cell 100. An advantage of this method of manufacturing and transporting the cathode 108 is that it does not require high temperature annealing as does a lithium ion cathode, and the cathode 108 can be transferred to a non-conductive or conductive surface. However, this illustrates only one possible method for forming a thin cathode layer-any other suitable method may be used instead. In some casesIn an embodiment, the cathode may be about 1nm and about 2nm thick.

During operation of the lithium-oxygen battery, lithium ions diffuse across the electrolyte from the anode 102 to the cathode 108, where they react with oxygen at the cathode 108 and form Li₂O₂. This movement of positive ions is accompanied by a flow of electrons in the current collector 107 towards the device 100, which represents a discharge effect. During the discharge, Li₂O₂Accumulates on the surface of the cathode 108.

Referring now to fig. 2, a method of manufacturing a battery is shown. Block 202 forms a cathode 108 on a first substrate. As described above, it is particularly contemplated that the cathode 108 may be formed of graphene and may be very thin (e.g., between about 1nm and 2 nm), and the first substrate may be, for example, copper or nickel. The cathode 108 may be formed by CVD or any other suitable deposition process that allows atoms of the cathode material (e.g., carbon) to so self-organize on the surface of the first substrate.

CVD is a deposition process in which deposits are formed as a result of chemical reactions between gaseous reactants at temperatures above room temperature (e.g., from about 25 c to about 900 c). The solid product of the reaction is deposited on the surface of the film, coating or layer where the solid product is to be formed. Variations of CVD processes include, but are not limited to, Atmospheric Pressure CVD (APCVD), Low Pressure CVD (LPCVD), Plasma Enhanced CVD (PECVD), and Metal Organic CVD (MOCVD), combinations of which may also be employed.

Block 204 attaches the handle layer to the cathode layer 108. It is specifically contemplated that the handle layer may be formed from, for example, PMMA, but it should be understood that any material having etch selectivity to the first and second substrates and the cathode 108 may be used instead. The treatment layer may be applied by any suitable mechanism including, for example, spin coating. As used herein, the term "selective" with respect to a material removal process means that a material removal rate of a first material is greater than a removal rate of at least another material of a structure for which the material removal process is applied.

Block 206 then uses a device such as FeCl₃The first substrate is etched away by a suitable wet or dry etch. The cathode 108 remains attached to the handle layer, andmay be moved to a position above a second substrate (which forms substrate 110 of finished cell 100). In block 207, the cathode 108 covered by the second substrate may be patterned using the handle layer as a photoresist. The cathode surface not covered by the treatment layer can be selectively removed. In an example where the cathode 108 is formed of graphene and the handle layer is formed of PMMA, the graphene cathode may be etched using oxygen plasma. And patterning by, for example, LiCoO₂，LiFePO₄Or LiNi_xMn_yCo_zO₂This is a simpler process than forming inorganic cathodes because they require harsh chemical etching methods. Building arrays (Building arrays) of cells and related circuit designs can be similarly simplified by simple micropatterning of graphene-based cathodes, particularly for micron-scale devices.

In block 208, the cathode 108 is attached to a second substrate. An adhesive may not be required to attach the cathode 108 to the second substrate-but rather an attractive force may exist due to, for example, Van der Waals interactions (Van der Waals interactions). The handle layer is then etched away using any suitable wet or dry etchant (e.g., acetone) to leave the cathode 108 on the substrate 110.

Block 212 adds current carriers 107 in the form of a conductive mesh on top of the cathode layer 108. Block 214 adds spacers 106 on the current carriers 107, covering the current carriers 107 and the cathode layer 108. May be formed of a sheet such as a porous film. Block 216 adds the anode 102 over the separator 106. The anode 102 is formed of a suitable metal, such as lithium, LiC₆,Li₇Ti₅O₁₂Or Li_4.4And (3) Si. Block 218 then introduces a liquid electrolyte between the anode 102 and the cathode 108. It is specifically contemplated that the electrolyte may be made of LiNO₃Or LiTFSI as a salt mix in an ether-based solvent (e.g., DME, TEGDME), any suitable electrolyte composition may be used instead.

It should be understood that aspects of the present invention will be described in terms of a given illustrative architecture; however, other architectures, structures, substrate materials, and process features and steps may be varied within the scope of aspects of the invention.

Referring now to FIG. 3, at a current density of 4 μ A/cm²When it is reacted with LiNO in a DME-based electrolyte₃Two different cathode materials mixed to facilitate solution-mediated discharge reactions in a lithium-oxygen cell show cell voltage (in volts) on the vertical axis 302 and charge capacity (in mAh/cm) on the horizontal axis 304²In units). Plot 308 shows a bare silicon or silicon dioxide layer and plot 306 shows a graphene layer mounted on the silicon or silicon dioxide layer. These cathodes were tested as anodes against lithium metal. For curve 306, a flat voltage curve is shown around 2.5V, but the bare wafer does not provide a significant discharge capacity. Electrolyte solutions based on TEGDME provided similar results.

By measuring Raman spectra (e.g., using a 532nm laser) of the pristine and discharged graphene cathodes, it was confirmed that the discharge product of the discharge reaction was Li₂O₂. After discharge at about 790cm^-1A peak appears corresponding to Li₂O₂The O-O bond in (1) extends. By having single/double layer graphene, Li can be achieved₂O₂The growth of (2). The graphene surface can be used as Li even in the presence of the non-conductive substrate 110₂O₂The seeds grown. Using TEGDME electrolyte and 0.5M LiNO₃Solutions, embodiments of the present invention may be used at a current density of 24 μ A/cm²About 60. mu. Ah/cm²The capacity of (c).

It will also be understood that when an element such as a layer, region or substrate is referred to as being "on" or "over" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or "directly over" another element, there are no intervening elements present. It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

The present embodiments may include a design for an integrated circuit chip that may be created in a graphical computer programming language and may be stored in a computer storage medium (such as a disk, tape, physical hard drive, or virtual hard drive, for example in a storage access network). If the designer does not fabricate chips or the photolithographic masks used to fabricate chips, the designer may transfer the resulting design by physical means (e.g., by providing a copy of the storage medium storing the design) or by electronic means (e.g., through the Internet) to such entities, directly or indirectly. The stored design is then converted into the appropriate format (e.g., GDSII) for the fabrication of photolithographic masks, which typically include multiple copies of the chip design in question that are to be formed on a wafer. The photolithographic masks are utilized to define areas of the wafer (and/or the layers on the wafer) to be etched or otherwise processed.

The methods as described herein may be used in the manufacture of integrated circuit chips. The resulting integrated circuit chips may be distributed by the manufacturer in raw wafer form (i.e., a single wafer having a plurality of unpackaged chips), bare chip, or packaged form. In the latter case, the chip is mounted in a single chip package (e.g., a plastic carrier with leads that are affixed to a motherboard or other higher level carrier) or in a multi-chip package (e.g., a ceramic carrier with one or both of surface interconnections or buried interconnections). In any event, the chip is then integrated with other chips, discrete circuit elements, and/or other signal processing devices as part of either (a) an intermediate product (e.g., a motherboard) or (b) an end product. The end product can be any product that contains integrated circuit chips, ranging from toys and other low-end applications to advanced computer products having a display, a keyboard or other input device, and a central processor.

It should also be understood that the material composition will be described in terms of the listed elements, such as SiGe. These compounds include different proportions of the elements in the compound, e.g. SiGe includes Si where x is less than or equal to 1_xGe_1-xAnd the like. In addition, chemical combinationOther elements may also be included in the article and still function according to current principles. Compounds with additional elements will be referred to herein as alloys.

Reference in the specification to "one embodiment" or "an embodiment" and other variations thereof means that a particular feature, structure, characteristic, or the like described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification, and any other variations, are not necessarily all referring to the same embodiment.

It should be understood that the use of any of the following "/", "and/or" and "at least one" is intended to encompass the selection of only the first listed option (a) or only the second listed option (B) or the selection of both options (a and B), for example in the case of "a/B", "a and/or B", "at least one of a and B". As another example, in the case of "a, B and/or C" and "at least one of a, B and C", such wording is intended to include selection of only the first listed option (a), or only the second listed option (B), or only the third listed option (C), or only the first and second listed options (a and B), or only the first and third options (a and C), or only the second and third listed options (B and C), or all three options (a and B and C). This can be extended for many of the items listed, as will be apparent to those of ordinary skill in this and related arts.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes" and/or "including," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Spatially relative terms, such as "below", "… …", "below", "… …", "above … …", "above … …", and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature as shown. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the term "below … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. In addition, it will also be understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Thus, a first element discussed below could be termed a second element without departing from the scope of the present invention.

Having described preferred embodiments for systems and methods (which are intended to be illustrative and not limiting), it is noted that modifications and variations can be made by persons skilled in the art in light of the above teachings. It is therefore to be understood that changes may be made in the particular embodiments disclosed which are within the scope of the invention as outlined by the appended claims. Having thus described aspects of the invention, with the details and particularity required by the patent laws, what is claimed and desired protected by letters patent is set forth in the appended claims.