Altered solid electrolyte interface lithium anodes and methods

Abstract

Anodes for Li batteries and energy storage devices are provided, including anodes with an altered solid electrolyte interface (SEI). The anode SEI formed by exposure to a dicarboxylic acid shows significant improvement in energy storage and stability. Methods of making anodes with an improved SEI include exposing a lithium-containing metal anode to an acid solution comprising one or more dicarboxylic acids for a time sufficient to cause the formation of an artificial SEI on a surface of the anode.

Description

Docket No. 1710.00065WOALTERED SOLID ELECTROLYTE INTERFACE LITHIUM ANODES AND METHODSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 694,476 filed September 13, 2024, the entire contents of which are incorporated herein by reference.TECHNICAL FIELD

[0002] The presently disclosed subject matter is directed to altered solid electrolyte interface (SEI) lithium (Li) anodes and methods for making the same. More particularly, the presently disclosed subject matter is directed to altering the SEI through surfacemodification Li anode for high-voltage Li batteries.BACKGROUND

[0003] Lithium-ion batteries are widely utilized for electric vehicles (EVs) and portable electronics. However, next-generation batteries with high energy density and long cycle life are essential to meet the increasing demand for EVs and other portable electronics. Lithium metal with 10 times higher theoretical capacity (3860 mAh / g) and the most negative electrochemical potential (-3.02 V vs SHE) makes it an ideal anode for nextgeneration batteries. Although Li metal is one of the best anodes, it suffers from problems including dendrite formation, unstable SEI, rapid consumption of electrolyte, and unrestrained volume changes during the plating and stripping of lithium. Several approaches such as modifying the electrolyte composition, incorporation of electrolyte additives, separator modification, artificial SEI formation, and lithium metal surface treatment have been proposed to either eliminate or suppress the problems associated with the lithium metal anode. However, none have completely or effectively solved the problems associated with Li metal as an anode.

[0004] The generation of a stable SEI on the surface of the Li anode is vital for the longterm performance of lithium metal batteries. The chemical composition and physical structure of the SEI can be tuned by modifying either the electrolyte composition or the electrode surface. Electrolyte modification may lead to other issues such as compatibility with other components of the battery such as corrosion of the current collector or oxidationDocket No. 1710.00065WO of the electrolyte on the surface of high voltage cathode materials. Modifying the surface of the anode not only avoids those problems but can also result in modification of the SEI without the need of changing the composition of the electrolyte. Several research groups have reported the surface modification of lithium anode as an effective strategy for improving lithium battery performance. However, there still remain significant deficiencies in methods to tune the organic and inorganic content in the SEI that lead to an improved anode performance.

[0005] Thus, there remains a need for improved and stable and / or artificial SEI on the surface of the Li anodes for improved anode performance, particularly in next-generation batteries.BRIEF SUMMARY

[0006] This summary lists several embodiments of the presently disclosed subject matter, and in many cases lists variations and permutations of these embodiments. This summary is merely exemplary of the numerous and varied embodiments. The mention of one or more representative features of a given embodiment is likewise exemplary. Such an embodiment can typically exist with or without the feature(s) mentioned; likewise, those features can be applied to other embodiments of the presently disclosed subject matter, whether listed in this summary or not. To avoid excessive repetition, this Summary does not list or suggest all possible combinations of such features.

[0007] In one aspect, provided is an altered solid electrolyte interface lithium anode, the anode comprising a lithium-containing metal anode and an artificial solid electrolyte interface (SEI) formed on a surface of the lithium-containing metal anode, wherein the artificial SEI is formed by exposure to one or more dicarboxylic acids. In some embodiments, the artificial SEI on the surface of the lithium-containing metal anode comprises a modified and / or tuned organic and inorganic content as compared to an unaltered and / or pristine lithium (Li) anode. In some embodiments, the stable and / or artificial SEI on the surface of the lithium-containing metal anode comprises a surface film comprising salts of Li forming the inorganic content and bridged alkyl groups forming the organic content on the surface of the lithium-containing metal anode.

[0008] In some embodiments, a composition of the artificial / altered SEI on the surface of the lithium-containing metal anode is tuned, as compared to pristine Li, based on an altered -CH2- / COOH ratio in the dicarboxylic acid. In some embodiments, acid groups inDocket No. 1710.00065WO the dicarboxylic acid react with Li to form a surface film on the surface of the anode, wherein the film comprises organic and inorganic salts of Li (e.g. RCOOLi, (COOLi)2, Li2COs. Li2O) and methylene groups. In some embodiments, the dicarboxylic acid comprises oxalic (OA), malonic (MA), succinic (SA), glutaric (GA), and adipic acid (AA).

[0009] In some embodiments, the altered SEI comprises dicarboxylic acid modified Li selected from the group consisting of oxalic acid modified Li (OA-Li), malonic acid modified Li (MA-Li), succinic acid modified Li (SA-Li), glutaric acid modified Li (GA- Li), and adipic acid modified Li (AA-Li). In some embodiments, the altered SEI comprises a carbonate rich surface film formed from the dicarboxylic acid reacting with Li in the anode. In some embodiments, the lithium-containing metal anode comprises a lithium- containing foil (e.g. LiMg foil, LiAl foil, LiAg foil, LiSn foil, and / or LiZn foil), a lithium metal foil, and / or a lithium alloy foil.

[0010] Also provided herein are methods of making an altered SEI lithium anode. Such methods comprise exposing a lithium-containing metal anode to an acid solution comprising one or more dicarboxylic acids for a time sufficient to cause the formation of an artificial solid electrolyte interface (SEI) on a surface of the anode. In some embodiments, the one or more dicarboxylic acids are selected from the group consisting of oxalic (OA), malonic (MA), succinic (SA), glutaric (GA), and adipic acid (AA). In some preferred embodiments, the dicarboxylic acid is MA. In some embodiments, the acid solution comprises a solvent, wherein the solution comprises about 5 % (W / W %) acid / solvent to about 20 % (W / W %) acid / solvent, optionally about 12 % (W / W %) acid / solvent, optionally wherein the solvent comprises tetrahydro furan (THF), diethyl ether, dioxolane, ethers, esters, carbonates, and related polar aprotic solvents. In some embodiments, the lithium-containing metal anode is exposed to the acid solution for about 5 minutes to about 1 hour, optionally about 5 minutes, about 10 minutes, about 15 minutes, about 20 minutes, about 25 minutes, about 30 minutes, about 35 minutes, about 40 minutes, about 45 minutes, about 50 minutes, about 55 minutes, or about 60 minutes.

[0011] In some embodiments of such methods, the methods further comprise washing and / or drying the lithium-containing metal anode upon removal from the acid solution. In some embodiments, such methods further comprise selecting a carboxylic acid based on a ratio of methylene groups to carboxylic acid groups (i.e. -CH2- / COOH) in the one or more dicarboxylic acids, optionally wherein the ratio of methylene groups to carboxylic acidDocket No. 1710.00065WO groups is 0, 0.5, 1, 1.5, and 2 for oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid, respectively.

[0012] In some embodiments, formation of an artificial SEI on a surface of the anode comprises formation of a surface film comprising salts of Li forming the inorganic content and bridged alkyl groups forming the organic content on the surface of the lithium- containing metal anode. In some embodiments, a composition of the artificial SEI on the surface of the lithium-containing metal anode is tuned, as compared to pristine Li, based on an altered -CH2- / COOH ratio in the dicarboxylic acid. In some embodiments, acid groups in the dicarboxylic acid react with Li to form a surface film on the surface of the anode, wherein the film comprises organic and inorganic salts of Li (e.g. RCOOLi, (COOLi)2, Li2CO3, Li2O) and methylene groups. In some embodiments, the artificial SEI comprises dicarboxylic acid modified Li selected from the group consisting of oxalic acid modified Li (OA-Li), malonic acid modified Li (MA-Li), succinic acid modified Li (SA- Li), glutaric acid modified Li (GA-Li), and adipic acid modified Li (AA-Li). In some embodiments, the SEI comprises an altered surface structure and / or altered surface morphology as compared to a smooth uniform surface structure of pristine lithium.

[0013] Also provided herein are energy storage devices comprising an altered SEI lithium anode as disclosed herein or an altered SEI lithium anode made by the methods disclosed herein. In some embodiments, such energy storage devices substantially maintain a specific capacity and / or a voltage profile after a plurality of cycles, optionally wherein the specific capacity and / or the voltage profile are maintained at least about '15' %,91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% at the 100thcycle as compared to a first cycle. In some embodiments, the energy storage devices comprise a battery, optionally a battery for an electric vehicle (EV) or in aviation field.

[0014] The above and other embodiments, objectives, features, and advantages of this invention will become still further apparent from the ensuing description, appended claims, and accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The presently disclosed subject matter can be better understood by referring to the following, example figure. The components in the figure are not necessarily to scale,Docket No. 1710.00065WO emphasis instead being placed upon illustrating the principles of the presently disclosed subject matter (often schematically). In the figure, like reference numerals designate corresponding parts throughout the different views. A further understanding of the presently disclosed subject matter can be obtained by reference to an embodiment set forth in the illustrations of the accompanying drawing. Although the illustrated embodiment is merely for purposes of example of systems for carrying out the presently disclosed subject matter, both the organization and method of operation of the presently disclosed subject matter, in general, together with further objectives and advantages thereof, may be more easily understood by reference to the drawings and the following description. The drawing is not intended to limit the scope of this presently disclosed subject matter, which is set forth with particularity in the claims as appended or as subsequently amended, but merely to clarify and provide examples of the presently disclosed subject matter.

[0016] FIG. 1 A Long-term cycling performance of Li / NMC622 cells containing pristine and surface-modified Lithium as an anode. The cells are cycled at C / 10 and C / 10 for initial three formation cycles and remaining at C / 7 charging and CH discharging.

[0017] FIG. IB galvanostatic charge-discharge cycling of Li / NMC622 cells containing pristine and surface-modified Lithium as an anode at different rates.

[0018] FIGS. 2A-2F Charge discharge voltage profile of Li / NMC622 cells with (A) pristine Li, (B)OA-Li (C) MA-Li (D) SA-Li E) GA-Li (F) AA-Li anodes at C / 7 charging CH discharge rates. The first cycle is the formation cycle conducted at C / 10 charge and C / 10 discharge rate.

[0019] FIGS. 3A-3C Electrochemical performance of Li / Li Symmetrical cell. (A) The Lithium plating and stripping of Li / Li symmetrical cells having pristine and surface- modified Li at 0.5 mA / cm2current density and 1 mAh capacity. (B) Magnified regions of Figure 3A at different time periods. (C) The Lithium plating and stripping of Li / Li symmetrical cells at different current densities.

[0020] FIGS. 4A and 4B Nyquist plots of NMC622 / Li cells having pristine and MA- Li as an anode, before (A) and after (B) 100 cycles of charge-discharge.

[0021] FIGS. 5A-5F FESEM images of Pristine Li (A), OA-Li (B), MA-Li (C), SA-Li (D), GA-Li (E), and AA-Li (F) anodes.

[0022] FIGS. 6 A and 6B Depth profiling analysis of cycled MA-Li (A) and pristine-Li (B) electrode in NMC622-Li cell after 100 cycles of charge-discharge. The figure shows high resolution XPS spectrum of Cis, FIs, Lils and Ols at different etching times.Docket No. 1710.00065WO

[0023] FIGS. 7A and 7B Depth profiling analysis. The elemental composition of MA-Li (A) and pristine Li (B) anodes after 100 cycles of charge-discharge.DETAILED DESCRIPTION

[0024] I. Definitions

[0025] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the presently disclosed subject matter.

[0026] While the following terms are believed to be well understood by one of ordinary skill in the art, the following definitions are set forth to facilitate explanation of the presently disclosed subject matter.

[0027] All technical and scientific terms used herein, unless otherwise defined below, are intended to have the same meaning as commonly understood by one of ordinary skill in the art. References to techniques employed herein are intended to refer to the techniques as commonly understood in the art, including variations on those techniques or substitutions of equivalent techniques that would be apparent to one of skill in the art. While the following terms are believed to be well understood by one of ordinary skill in the art, the following definitions are set forth to facilitate explanation of the presently disclosed subject matter.

[0028] Components referred to by chemical name or formula anywhere in the specification or claims hereof, whether referred to in the singular or plural, are identified as they exist prior to coming into contact with another substance referred to by chemical name or chemical type (e.g., another component, a solvent, or etc.). It matters not what chemical changes, transformations and / or reactions, if any, take place in the resulting mixture or solution as such changes, transformations, and / or reactions are the natural result of bringing the specified components together under the conditions called for pursuant to this disclosure. Thus, the components are identified as ingredients to be brought together in connection with performing a desired operation or in forming a desired composition. Also, even though the claims hereinafter may refer to substances, components and / or ingredients in the present tense ("comprises", "is", etc.), the reference is to the substance, component or ingredient as it existed at the time just before it was first contacted, blended or mixed with one or more other substances, components and / or ingredients in accordance with the present disclosure. The fact that a substance, component or ingredient may haveDocket No. 1710.00065WO lost its original identity through a chemical reaction or transformation during the course of contacting, blending or mixing operations, if conducted in accordance with this disclosure and with ordinary skill of a chemist, is thus of no practical concern.

[0029] In describing the presently disclosed subject matter, it will be understood that a number of techniques and steps are disclosed. Each of these has individual benefit and each can also be used in conjunction with one or more, or in some cases all, of the other disclosed techniques.

[0030] Accordingly, for the sake of clarity, this description will refrain from repeating every possible combination of the individual steps in an unnecessary fashion. Nevertheless, the specification and claims should be read with the understanding that such combinations are entirely within the scope of the invention and the claims.

[0031] Following long-standing patent law convention, the terms “a”, “an”, and “the” refer to “one or more” when used in this application, including the claims. Thus, for example, reference to "a cell" includes a plurality of such cells, and so forth.

[0032] Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter.

[0033] As used herein, the term “about,” when referring to a value or to an amount of a composition, dose, mass, weight, temperature, time, volume, concentration, percentage, etc., is meant to encompass variations of in some embodiments ±20%, in some embodiments ±10%, in some embodiments ±5%, in some embodiments ±1%, in some embodiments ±0.5%, and in some embodiments ±0.1% from the specified amount, as such variations are appropriate to perform the disclosed methods or employ the disclosed compositions.

[0034] The term “comprising”, which is synonymous with “including” “containing” or “characterized by” is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. “Comprising” is a term of art used in claim language which means that the named elements are essential, but other elements can be added and still form a construct within the scope of the claim.Docket No. 1710.00065WO

[0035] As used herein, the phrase “consisting of’ excludes any element, step, or ingredient not specified in the claim. When the phrase “consists of’ appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.

[0036] As used herein, the phrase “consisting essentially of’ limits the scope of a claim to the specified materials or steps, plus those that do not materially affect the basic and novel characteristic(s) of the claimed subject matter.

[0037] With respect to the terms “comprising”, “consisting of”, and “consisting essentially of”, where one of these three terms is used herein, the presently disclosed and claimed subject matter can include the use of either of the other two terms.

[0038] As used herein, the term “and / or” when used in the context of a listing of entities, refers to the entities being present singly or in combination. Thus, for example, the phrase “A, B, C, and / or D” includes A, B, C, and D individually, but also includes any and all combinations and subcombinations of A, B, C, and D.

[0039] II. Altered solid electrolyte interface lithium anodes and methods for making same

[0040] Several research groups have reported the surface modification of lithium anode as an effective strategy for improving lithium battery performance. However, none have effectively developed methods to tune the organic and inorganic content in the SEI that led to an improved anode performance. Based on the research disclosed herein, and without being bound by any particular theory or mechanism of action, it is now realized that the organic and inorganic layers are likely important for stable performance of SEI. Nevertheless, it appears to be essential to understand and tune the degree of organic and inorganic content in the SEI to realize the full potential of the Li anode.

[0041] As such, disclosed herein, a series of organic dicarboxylic acids have been investigated as surface modifying agents for lithium metal anodes using a combination of ex-situ surface analysis and electrochemical techniques. The ex-situ surface analysis reveals that surface film contains organic and inorganic components which can be tuned by adjusting the number of methyl groups in the dicarboxylic acids. The acid group reacts with lithium metal to from salts of lithium which makes the inorganic part of the surface film while the bridging alkyl group makes the organic part of the surface film. SurfaceDocket No. 1710.00065WO modified Li anodes were used to assemble symmetrical and asymmetrical (NMC 622 cathode and Li anode) cells with carbonate-based electrolytes. The electrochemical analysis reveals that the surface modification of lithium metal anode improves the performance of the lithium anode and the battery.

[0042] Thus, in some aspects, provided herein are optimized and / or tuned anodes, including Li anodes, and particularly those with an altered SEI. Such altered SEI Li anodes can include a lithium-containing metal anode and an artificial SEI (also referred to in some embodiments as a stable SEI, or an SEI that is not a naturally formed interface on pristine Li) formed on a surface of the lithium-containing metal anode, where the SEI is formed by exposure to a dicarboxylic acid. The altered SEI Li anode may also include where the artificial SEI on the surface of the Li-containing metal anode includes a modified and / or tuned organic and inorganic content as compared to an naturally formed one on pristine Li anode. The altered SEI Li anode may also include where the artificial SEI on the surface of Li-containing metal anode includes a surface film includes salts of Li forming the inorganic content and bridged alkyl groups forming the organic content on the surface of the Li-containing metal anode. The altered SEI Li anode may also include, where the dicarboxylic acid includes any dicarboxylic acid, including but not limited to oxalic (OA), malonic (MA), succinic (SA), glutaric (GA), and adipic acid (AA). The altered SEI Li anode may also include where the artificial SEI includes any dicarboxylic acid modified Li where the dicarboxylic acid is selected from, but not limited to, oxalic acid modified Li (OA-Li), malonic acid modified Li (MA-Li), succinic acid modified Li (SA-Li), glutaric acid modified Li (GA-Li), and adipic acid modified Li (AA-Li). The altered SEI Li anode may also include where the artificial SEI includes a carbonate rich surface film formed from the dicarboxylic acid reacting with Li in the anode.

[0043] The altered SEI lithium anodes herein may also include where a composition of the artificial SEI on the surface of the lithium-containing metal anode is tuned, as compared to pristine Li, based on an altered -CH2- / COOH ratio in the dicarboxylic acid. The altered SEI lithium anode may also include where acid groups in the dicarboxylic acid react with Li to form a surface film on the surface of the anode, where the film includes organic and inorganic salts of Li (e.g. RCOOLi, (COOLi)2, Li2CO3. Li2O) and methylene groups.

[0044] The disclosed altered SEI lithium anodes may also include where the lithium- containing metal anode includes a lithium-containing foil (e.g. LiMg foil, LiAl foil, LiAgDocket No. 1710.00065WO foil, LiSn foil, and / or LiZn foil), a lithium metal foil, and / or a lithium alloy foil, although any suitable Li foil or composite material can be used.

[0045] Also provided herein are methods of making altered SEI Li anodes. Such methods include exposing a Li-containing metal anode to an acid solution that includes one or more dicarboxylic acids for a time sufficient to cause the formation of an artificial SEI on a surface of the Li anode.

[0046] The methods may also include where the one or more dicarboxylic acids are selected from the group consisting of includes oxalic (OA), malonic (MA), succinic (SA), glutaric (GA), and adipic acid (AA). In some preferred embodiments, the dicarboxylic acid can be MA.

[0047] In some aspects, the acid solution for making the SEI Li anodes can include Tetrahydrofuran (THF), where the solution includes about 1 % (W / W %) acid / THF to about 50 % (W / W %) acid / THF, or about 5 % (W / W %) acid / THF to about 20 % (W / W %) acid / THF, optionally about 12 % (W / W %) acid / THF. The methods may also include where the Li-containing metal anode is exposed to the acid solution for about 5 minutes to about 1 hour, optionally about 5 minutes, about 10 minutes, about 15 minutes, about 20 minutes, about 25 minutes, about 30 minutes, about 35 minutes, about 40 minutes, about 45 minutes, about 50 minutes, about 55 minutes, or about 60 minutes.

[0048] In some aspects, such methods may also include where the method further includes washing and / or drying the lithium-containing metal anode upon removal from the acid solution, as discussed further in the Examples.

[0049] Dicarboxylic acids used herein can be selected based on a ratio of methylene groups to carboxylic acid groups (i.e. -CH2- / COOH) in the one or more dicarboxylic acids, optionally where the ratio of methylene groups to carboxylic acid groups is 0, 0.5, 1, 1.5, and 2 for oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid, respectively. The formation of an artificial SEI on a surface of the anode includes formation of a surface film with salts of Li forming the inorganic content and bridged alkyl groups forming the organic content on the surface of the lithium-containing metal anode. Using this information, the composition of the artificial SEI on the surface of the lithium- containing metal anode can be tuned, as compared to pristine Li, based on an altered CH2- / COOH ratio in the dicarboxylic acid used.

[0050] The acid groups in the dicarboxylic acid react with Li to form a surface film on the surface of the anode, where the film includes organic and inorganic salts of Li (e.g.Docket No. 1710.00065WORCOOLi, (COOLi)2, L12CO3, H2O) and methylene groups. Thus, the disclosed methods may also include where the artificial SEI includes dicarboxylic acid modified Li selected from the group consisting of oxalic acid modified Li (OA-Li), malonic acid modified Li (MA-Li), succinic acid modified Li (SA-Li), glutaric acid modified Li (GA-Li), and adipic acid modified Li (AA-Li).

[0051] Provided herein are energy storage devices, and more particularly energy storage devices with an altered SEI lithium anode as disclosed herein. Using the disclosed altered SEI lithium anodes, such energy storage devices can realize substantially improved performance, particularly as compared to energy storage devices using standard anodes. For example, altered SEI lithium anode energy storage devices as disclosed herein can substantially maintain a specific capacity and / or a voltage profile after a plurality of cycles, e.g. 100 or more cycles. The specific capacity and / or the voltage profile can be maintained, as the data herein shows, at a level of least about 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% at the 100thcycle as compared to the first cycle. These improved energy storage devices include the disclosed anodes with an SEI that is more robust and can withstand even the high current densities required under heavy usage and loads. Such improved performance can in some aspects be attributed to the acids reacting with Li to form a carbonate rich surface film which retains its chemical characteristics even after 100 cycles, suggesting good stability of the surface film. For example, and as shown in the data herein, the modified electrodes, maintain a high specific capacity after numerous cycles, e.g. 141 mAh / g specific capacity after 100 cycles.

[0052] The energy storage devices include any energy storage device or battery, including Li batteries and batteries for electric vehicles (EVs). The improved performance of such batteries, based at least in part on the surprising performance characteristics of the altered SEI lithium anode, will be well suited for various applications where storing energy is required.

[0053] The anodes, methods and devices herein employing the disclosed altered SEI lithium anodes can use any suitable Li material for the Li anode. For example, suitable lithium-containing foils include lithium metal foil, and lithium alloy foils, including LiMg foil, LiAl foil, LiAg foil, LiSn foil, and LiZn foil. Lithium metal foil is often preferred.

[0054] Lithium-containing foils have a thickness typically ranging from about 20 pm to about 200 pm, more often about 40 pm to about 150 pm. This parameter has not beenDocket No. 1710.00065WO optimized, although it is recognized that thicker foils transfer larger amounts of lithium under the same patterning conditions.

[0055] The anode material can include other elements or materials besides Li, including graphite, one or more silicon materials, blends of graphite and one or more silicon materials, various metals and alloys, which alloys can be lithium alloys. Anode materials, especially for lithium storage devices and batteries, often include graphite or blends of graphite and one or more silicon materials.

[0056] Suitable lithium-containing salts in the practice of some embodiments of the presently disclosed subject matter include lithium perchlorate, lithium nitrate, lithium thiocyanate, lithium aluminate, lithium tetrachloroaluminate, lithium tetrafluoroaluminate, lithium tetraphenylborate, lithium tetrafluoroborate, lithium bis(oxolato)borate (LiBOB), lithium di(fluoro)(oxalato)borate, lithium hexafluorophosphate, lithium hexafluoroarsenate, ithium alkyl carbonates in which the alkyl group has 1 to 6 carbon atoms, lithium methyl sulfonate, lithium trifluoromethylsulfonate, lithium pentafluoroethylsulfonate , lithium pentafluorophenylsulfonate, lithium fluorosulfonate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(pentafluoroethylsulfonyl)imide, lithium (ethylsulfonyl)(trifluoromethylsulfonyl)imide, and mixtures of any two or more of the foregoing. Preferred lithium-containing salts include lithium hexafluorophosphate, lithium tetrafluoroborate, lithium di(fluoro)(oxolato)borate, and lithium bis(oxolato)borate.

[0057] Typical concentrations for the lithium-containing salt in the solution for the electrochemical cell are in the range of about 0. 1 M to about 2.5 M, preferably about 0.5 M to about 2 M, more preferably about 0.75 M to about 1.75 M, and still more preferably about 0.95 M to about 1.5 M. When more than one lithium-containing salt forms the lithium- containing electrolyte, the concentration refers to the total concentration of all of the lithium- containing salts present in the electrolyte solution.

[0058] EXAMPLES

[0059] The following examples are included to further illustrate various embodiments of the presently disclosed subject matter. However, those of ordinary skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specificDocket No. 1710.00065WO embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the presently disclosed subject matter.

[0060] EXAMPLE 1

[0061] Materials

[0062] Tetrahydrofuran (THF), Succinic acid (99% purity), and Glutaric acid (99% purity) were purchased from Sigma Aldrich. Oxalic acid (99% purity) and Malonic acids (99% purity), were obtained from Alfa Aesar. All the chemicals except THF were used without further purification. THF was dried with 3A molecular sieves (from Sigma Aldrich) at least 24 hours before use. Ethylene carbonate (EC) and Diethyl carbonate (DEC) and Fluoroethylene carbonate (FEC) and Lithium hexafluorophaphate (LiPFs) were supplied by Gotion. Celgard 2325 microporous ployethylene sheet was used as separator. Lithium metal (75 pm) on a copper sheet (Li@Cu) and NMC-622 electrodes were prepared by Albemarle and used as the anode and cathode, respectively. The thickness of Li on copper foil is 75pm and the average loading active material on the cathode is ~ 20 mg / cm2.

[0063] Preparation of electrodes and electrolyte

[0064] The cathode was cut into a 14 mm diameter disk and dried and stored in the glove box to prevent the adsorption of moisture and other passive layer building over time. Li@Cu electrode cut in to 16 mm diameter disk and used for the surface modification. All the modification procedure was conducted in an argon-filled glove box with oxygen and moisture levels less than 0.1 ppm.

[0065] 12 % (W / W %) Acid / THF solution was prepared and used to modify the surface of the lithium electrode. THF solvent was dried with 3A molecular sieves for 24 h before use. A known amount of salt (Oxalic acid, Malonic acid, succinic acid, glutaric acid, and adipic acid) was added to the ultra-dry THF solvent and stirred for 30 min to prepare the solution. Lithium electrodes were dropped into acid / THF solution, the solution was shaken well to make sure all the electrodes are exposed to the solution. After 15 minutes, the electrodes were washed with excess THF solvent to remove the acid / THF solution and unreactive residues on the electrodes. The washed electrodes were dried in a vacuum overnight. The vacuum-dried surface-modified electrodes are used for physical andDocket No. 1710.00065WO electrochemical characterization. A I M LiPFe in EC: DEC (3:7) solvent mixture with 5% FEC (wt %) as an additive was prepared and used as an electrolyte.

[0066] Cell assembly

[0067] The 2032-type symmetrical (Li / Li) and asymmetrical (Li / NMC622) coin cells were assembled in Argon glove box as follows. NMC 622 cathode was placed in the coin cell caps followed by the addition of 20 pL of electrolyte. The cathode was covered with a separator (celgard 2325 with 19 mm diameter), and another 20 pL electrolyte was added on top of the separator. Li anode was placed in proper alignment with the cathode followed by stainless steel spacer and spring. The cell was closed with a cap and gasket and sealed. Lithium symmetrical cells were also assembled like the NMC622 / Li cells, except with lithium electrodes and 30 pL of electrolytes on both sides of the separator.

[0068] Physical and Electrochemical Characterization

[0069] Galvanostatic charge-discharge cycling of NMC622 / Li cells and plating stripping of symmetrical cells was carried out with an Arbin BT2000 battery tester. Constant current and constant voltage (CC-CV) mode was used for charge discharge cycling. NMC622 / Li cells were cycled between 4.3 V to 2.5 V vs. Li / Li+at different rates. Each cell cycled at C / 10 for 3 cycles for formation of SEI before cycling at different rates. Life cycle testing was carried out at C / 7 charge and C / 2 discharge rates and for the rate capability test, the cells were cycled at C / 20, C / 10, C / 5, C / 2, 1C, 3C, and C / 5 current densities. To measure the impedance of the cell, electrochemical impedance spectroscopic (EIS) analysis was conducted with a Biologic (model VSP) potentiostat and galvanostat. EIS spectra were recorded at OCV of the cell and between 0.05 Hz to 500 kHz frequency. The symmetrical cells were cycled at 0.5 mA / cm2current density and 1 mAh capacity. The symmetrical cells are also tested at different current densities. The electrodes are collected from the cycled cells, washed and dried in a vacuum to remove the electrolyte residues. The chemical composition of the lithium electrode surface before and after cycling was analyzed using X-ray photoelectron spectroscopy (XPS). The XPS measurements were conducted using k-alpha series x-ray photoelectron spectrometer from Thermo Scientific with ALKa x-ray source and 400 pm spot size. Samples were transferred to the XPS in an air free transfer device. Microscopic images of surface modified Li electrode were recorded using Field Emission Scanning electron microscopy (FESEM) from Zeiss (Sigma- VP).Docket No. 1710.00065WO

[0070] EXAMPLE 2

[0071] Electrochemical Performance of SEI modified Li anode

[0072] The electrochemical performance of the surface-modified lithium metal is evaluated by constructing two types of coin cells. The first type is a cell with a NMC622 cathode and a modified lithium anode while the second type is a symmetrical cell with two lithium anodes. The specific capacity of Li / NMC622 cells with cycle number is provided in Fig. 1 A and 1 B. The cells with pristine lithium have 175 m Ah / g specific capacity during formation cycling and the capacity gradually decreases with cycle number. The capacity decreases rapidly after 60 cycles and drops to 65 mAh / g after 100 cycles, retaining only 41 % of the initial specific capacity. The steep decrease in the capacity can be attributed to the formation of dead lithium, due to inadequate SEI formation on the lithium anode. Alternatively, the cells containing surface modified lithium have better capacity retention after 100 cycles. The specific capacities of surface modified lithium cells after 100 cycles of charge-discharge are 123 mAh / g, 141 mAh / g 136 mAh / g 121 mAh / g, and 107 mAh / g for oxalic (OA-Li), malonic (MA-Li), succinic (SA-Li), glutaric (GA-Li), and adipic acid modified lithium (AA-Li) containing cells, respectively and the specific capacity retentions are 75%, 85%, 90%, 88%, and 81 %, respectively. The capacity retention of modified Li is almost double the pristine Li. Among all the dicarboxylic acid modified lithium under investigation, MA-Li has the best performance with 141 mAh / g specific capacity after 100 cycles. MA-Li not only retains high capacity but also delivers a high specific capacity through 100 cycles. It is interesting to note that the specific capacity retention is increased from OA-Li to MA-Li and decreased to AA-Li. In addition, the percent specific capacity retention is increased from OA-Li to SA-Li and decreased to AA-Li. The performance correlates with the ratio of methylene groups to carboxylic acid groups (-CH2- / COOH) in dicarboxylic acids which are zero, 0.5, and 1, 1-5, and 2 for oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid respectively. During the surface modification of the lithium metal, the acid groups in dicarboxylic acid react with lithium to form a surface film containing different organic and inorganic salts of lithium (RCOOLi, (COOLih, Li2CC>3 Li2O... etc) and methylene groups. Further analysis of the surface films will be discussed below. Upon electrochemical cycling, the surface film reacts with the electrolyte to form an artificial SEI having a lithium-ion conductive inorganic part and a flexible methylene chain containing organic part. The inorganic partDocket No. 1710.00065WO is lithium ion conductive and is sensitive to volume changes of the lithium while the organic part is flexible to volume changes but hinders the lithium-ion transport. The SEI with the appropriate chemical composition (inorganic and organic parts) can in some embodiments be important to improve the long-term performance of the lithium metal anode. The composition of the SEI can be tuned by altering the -CH2- / COOH ratio in dicarboxylic acid.

[0073] EXAMPLE S

[0074] Galvanostatic charge-discharge cycling of surface -modified Lithium as an anode

[0075] Another important factor affecting the anode’s performance is the reactivity of dicarboxylic acid toward lithium. The reactivity of the dicarboxylic acid decreases with the number of methylene groups (due to electron donating nature of methyl group). The highly reactive oxalic acid reacts vigorously with lithium forming a thick dark surface film whereas less reactive adipic acid forms a thin surface film. A thick surface film not only increases the overall cell resistance but also consumes more lithium. In the case of OA-Li, the capacity retention was limited by the large consumption of lithium during the surface modification whereas SA-Li shows less specific capacity but high-capacity retention due to the generation of a flexible, resistive and thin surface film. Similar reasons can be attributed to GA-Li and AA-Li anodes. MA-Li shows the best specific capacity and better capacity retention among all, which may have the optimum composition of organic and inorganic portions of the SEI.

[0076] The Li / NMC622 cells cycled at different C rates, provided in Figure IB, reveals similar rate performance for most of the surface modified lithium. However, the OA-Li has rapid loss of specific capacity at higher rates which can be attributed to a greater consumption of lithium during the surface modification and the formation of mechanically fragile SEI. The MA-Li cells have superior rate performance, suggesting better SEI formation on the Li anode.

[0077] EXAMPLE 4

[0078] Evaluation of voltage profile of surface-modified Lithium as an anodeDocket No. 1710.00065WO

[0079] Further, the electrochemical performance of surface-modified lithium was analyzed by monitoring the voltage profile of the NMC622 / L1 cells, provided in Figures 2A-2F. The first formation cycle has charge and discharge rates of C / 10 and C / 10, respectively, while the other cycles are at C / 7 and C / 2 charge and discharge rates, respectively. The pristine lithium shows a steady charge-discharge voltage profile for the first 50 cycles, but the discharge voltage drops significantly thereafter and reaches a minimum on the 100thcycle. Interestingly, the charging plot at its 100thcycle shows negligible charging during the constant current (CC) mode and charging only occurs during the constant voltage (CV) mode, which results in high resistance of the cell due to minimal lithium deposition on the anode. A similar result is observed for the OA-Li anode in NMC622 / Li cells. Alternatively, the other surface-modified lithium anodes have a slight reduction in specific capacity and small changes in the voltage profile around the 100thcycle. Thus, the other modified lithium metal anodes have much better performance retention than the pristine or OA-Li anode cells. The voltage profile for the MA-Li cell has only small changes to the charge-discharge voltage profile after 100 cycles although there is a small decrease in the specific capacity of the cell. This can be attributed to the nature of SEI generated on the lithium metal surface during treatment with MA, the detailed analysis of SEI is given later in this work.

[0080] EXAMPLE S

[0081] Evaluation of plating and stripping cycles cells with surface-modified Lithium as an anode

[0082] The electrochemical performance of the surface-modified electrodes has been further evaluated by constructing Li / / Li symmetrical cells. The plating / stripping of Li / Li symmetrical cells at 0.5 mA / cm2current density and 1 mAh capacity are provided in Figures 3A and 3B. Similar to the performance of NMC622 / Li cells, the MA-Li has superior performance both in terms of voltage polarization and cycle life. MA-Li has plating and stripping performance for about 450 h without an increase in voltage polarization. The superior performance of MA-Li cells can be attributed to stable artificial SEI formation on the surface of the Li electrode, as discussed below. The plating and stripping performance of the Li / Li symmetrical cells at different current densities are provided in Figure 3C. The plating and stripping cycles were conducted for 1 hour at each current density. At low current density, all the cells including pristine Li / Li symmetricalDocket No. 1710.00065WO cells show similar performance but at high current densities, MA-Li outperforms all other electrodes. This suggests that the SEI formed on the surface of the MA-Li is more robust and can withstand even the high current densities.

[0083] EXAMPLE 6

[0084] Electrochemical impedance spectroscopy (EIS) of cells with surface-modified Lithium as an anode

[0085] Electrochemical impedance spectroscopy (EIS) is a good nondestructive tool to study the impedance of the electrode and electrolytes. To understand the effect of surface modification of lithium, the EIS of NMC622 / Li cells was recorded before and after cycling. The Nyquist plots of NMC622 / Li cells containing pristine and MA-Li anodes, before and after cycling are provided in Figure 4A and 4B, respectively. Before cycling, the EIS contains two highly merged semicircles, the small semicircle at the high-frequency region corresponds to SEI or surface film, while the large semicircle in the mid-frequency range corresponds to the charge transfer resistance (Ret), and the straight line at the low- frequency region corresponds to the diffusion of the lithium-ion through a surface of the electrodes. The overall cell resistance is high in the case of surface-modified lithium anodes compared to pristine lithium (Figure 4A) which can be attributed to the surface film on the modified electrode. The Nyquist plot of the NMC622 / Li cells after 100 cycles is provided in Figure 4B. The Nyquist plots show highly resolved semicircles, and the overall cell resistance has decreased drastically which can be attributed to conductive surface film formation on the electrodes. The overall cell impedance has decreased both in the case of pristine and MA-Li containing cells. However, the reduction is greater in the case of MA-Li than that of Pristine Li. Moreover, the semicircle at the high-frequency region (see Figure 3B insert) is smaller for the MA-Li cell than that of the pristine cell, which indicates better SEI formation on MA-Li cells than that of pristine Li Cell. However, the second Semicircle corresponding to the charge transfer is larger for MA-Li than that of pristine Li. The organic part of SEI which is resistive in nature is responsible for the higher Ret of MA-Li cells. All the other surface modified cells have similar trends.

[0086] EXAMPLE ?

[0087] Analysis of surface morphology of surface-modified Lithium as an anodeDocket No. 1710.00065WO

[0088] To understand the electrochemical behavior of the surface modified lithium anodes, the surface morphology and chemical composition has been investigated with FESEM and XPS, respectively. The FESEM images of the pristine and surface-modified anodes are provided in Figures 5A-5F. As shown in Figure 5A, the pristine lithium has a smooth uniform surface. Alternatively, the surface modified anodes have a different morphology. The OA-Li (Figure 5B) has an irregular surface morphology which is likely formed due to the aggressive reactivity of oxalic acid towards lithium. MA-Li and SA-Li show a spherical deposition with large and small grain boundaries, respectively. GA-Li surface morphology reveals the deposition of particles with sharp grain boundaries which do not completely cover the surface of lithium. AA-Li shows densely precipitated small particles on the surface of lithium. The formation of diverse morphologies on the surface of lithium can be attributed to the difference in the reactivity of dicarboxylic acids towards lithium and the formation of lithium salts having different crystallographic phases.

[0089] Visual examination of the surface modified Li further supports the FESEM data. The pristine Li exhibits a shiny surface whereas surface-modified lithium anodes have a dark surface film. The darkness decreases from OA-Li to AA-Li. The thick dark surface film on OA-Li suggests the large consumption of lithium metal during surface modification which supports the irregular morphology in FESEM images (Figure 4A). MA-Li, SA-Li, GA-Li and AA-Li have thinner, compact and uniform surface films consistent with the FESEM data.

[0090] To further understand the effect of surface modification on artificial SEI formation, the chemical composition of pristine and surface modified electrodes have been analyzed using XPS. The carbon content in the surface film increases and Li and oxygen content decreases from OA-Li to AA-Li. This anticipated change in the elemental composition can be attributed to the number of -CH2 groups in the dicarboxylic acid. The XPS spectra and elemental composition of lithium electrodes after 100 cycles of charge / discharge were analyzed. The high-resolution spectra of Cis, Ols, Lils and FIs have similar features with small differences although the elemental compositions vary significantly. Among all the cycled electrodes, MA-Li shows less carbon (organic part) and more LiF (inorganic part) than the other electrodes investigated. Higher concentrations of organic components in SEI increase the resistance of the electrode which affects the overall cell performance. High concentration of LiF facilitates lithium-ion transport which higher carbon content better accommodates the volume changes of the lithium electrode.Docket No. 1710.00065WOBoth organic (carbon content) and inorganic (LiF and other lithium salts) have optimum concentrations in MA-Li which are essential for better performance of the electrode. These results are well aligned with the electrochemical performance of the electrodes discussed above.

[0091] EXAMPLE S

[0092] XPS depth profiling analysis of surface-modified Lithium as an anode

[0093] To further understand, the SEI, XPS depth profiling analysis of pristine Li and the best performing modified lithium, MA-Li, were conducted after 100 cycles (Figures 6A and 6B). Figure 6A shows depth profiling analysis of MA-Li after 100 cycles in NMC622-Li cell. The Cis spectrum (Figure 6 A) contains peaks at 284.9 eV (C-C), 287.2 eV(O-C=O), 289.1 eV (C=O), and 291 eV (ROCO2R) corresponding to frequently observed oxygenated species in the SEI such as carbonates and alkyl carbonates and polymeric compounds. However, the peak corresponding to alkyl carbonate at 291 eV is not observed in Cis spectrum of pristine lithium (Figure 6B).

[0094] Malonic acid reacts with lithium and forms a carbonate rich surface film which retains its chemical characteristics even after 100 cycles, suggesting good stability of the surface film. The Lils and FIs peaks contain similar features in MA-Li and pristine Li with two peaks at 685.2 eV ( LiF) and 687.6 eV ( LixPO^Fz) observed in the FIs spectrum and a single broad peak observed at 56 eV (LiF) in Lils spectrum. However, the peak corresponding to LixPO^Fz has greater intensity for MA-Li than for the Pristine-Li which suggests greater reactivity of the surface film with electrolyte salt (LiPFe) for MA-Li. The Ol s peak in both MA-Li and pristine Li contains two peaks at 532 eV (C=O) and 534 eV (C-O) which is consistent with the species observed in the Cis spectra. Further information can be obtained by looking at the XPS spectra features and elemental composition during etching. The Cis spectrum of MA-Li shows more intensive peaks corresponding to oxygenated species such as carbonates than that of the pristine Li. Similarly, FIs spectrum also contains greater intensity peaks corresponding to LiF and LijPOjF species for MA- Li than that for pristine Li. Interestingly, the peak at 687.6 eV corresponding to LixPOyFzis more intense even after 6 min of etching time, suggesting an even distribution of inorganic species throughout the SEI layer. In the depth profiling of pristine lithium, the peaks corresponding to oxygenated species in the Ci s spectrum and peaks corresponding toDocket No. 1710.00065WOLixPOyFz are significantly decrease with depth. Interestingly, Ols shows an emerging peak at 528.1 eV which corresponds to metal oxide. The metal oxide peak is not observed in Ols spectrum of MA-Li. The new metal oxide peak may arise from the copper current collector which was exposed due to complete consumption of lithium during cycling. The elemental composition of MA-Li and pristine Li at different etch levels are shown in Figures 7A and 7B. One of the major differences in the chemical composition of the SEI is that the SEI on MA-Li has a more even distribution of fluorine and carbon throughout the SEI than that of pristine-Li. In the case of pristine lithium, the major component of the SEI is LiF and other lithium salts. Alternatively, the SEI for MA-Li contains an even distribution of lithium salts but also contains a flexible carbon network throughout the SEI. The SEI on MA-Li can be depicted as distribution of inorganic nanoparticles on a carbon network.

[0095] EXAMPLE 9

[0096] Surface-modified Lithium performance under high relative humidity

[0097] The performance of the surface-modified Lithium anodes disclosed here was further analyzed under high humidity or wet environment conditions, an important characteristic for commercial applications.

[0098] Pristine and MA coated Li samples were tested before and after exposure in a wet environment, including 30% relative humidity (RH), using the same coin cell electrochemical testing protocols disclosed hereinabove. Samples were tested at 0 hours and 3 hours exposure to 30% RH at an initial capacity and after 100 cycles. Results are presented in Table 1.Table 1.Docket No. 1710.00065WO

[0099] The results show that the MA Oh and 3h (before and after exposure in high humidity condition- 30% RH) anodes show similar electrochemical performance. In comparison, the pristine Li anode can't maintain its performance if it exposed in such wet conditions (pristine Oh vs. 3h). This demonstrates that the MA treated Li can tolerant a high humidity condition compared to non-treated pristine Li anodes.

[0100] Summary and Conclusion of Examples 1-9

[0101] The physical structure and chemical composition of the SEI affect the performance of the lithium anode. The presently disclosed subject matter investigated the tuning of SEI chemical composition and structure through the surface modification of the lithium metal anode. A series of dicarboxylic acids, including oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid were employed to modify the surface of the lithium anode. The lithium metal (NMC622 / Li) cells with modified electrodes show improved specific capacity and cycle life. Among the modified electrodes, MA-Li has the best performance retaining 141 mAh / g specific capacity after 100 cycles. XPS analysis of lithium electrodes reveals that the SEI formed on the surface of modified electrodes contains organic polymeric compounds and inorganic lithium salts. The performance of the electrode is strongly influenced by the relative quantity of organic and inorganic components in the SEI. Electrodes with high concentration inorganic components in the SEI have higher specific capacity but poor cycle life. The electrodes with high concentrations of organic components (SA-Li, GA-Li and AA-Li) have better cycle life but lower specific capacity. MA-Li anode with an intermediate concentration of organic and inorganic components in SEI retains high specific capacity even after 100 cycles of charge discharge.

[0102] While the present invention has been described in terms of one or more preferred embodiments, it is to be understood that other modifications may be made without departing from the scope of the invention, which is set forth in the claims below.

Claims

Docket No. 1710.00065WOCLAIMSWhat is claimed is:

1. An altered solid electrolyte interface lithium anode, the anode comprising a lithium- containing metal anode and an artificial solid electrolyte interface (SEI) formed on a surface of the lithium-containing metal anode, wherein the SEI is formed by exposure to one or more dicarboxylic acids.

2. The altered SEI lithium anode of claim 1, wherein the artificial SEI on the surface of the lithium-containing metal anode comprises a modified and / or tuned organic and inorganic content as compared to an unaltered and / or pristine lithium (Li) anode.

3. The altered SEI lithium anode of claim 1 or 2, wherein the artificial SEI on the surface of lithium-containing metal anode comprises a surface film comprising salts of Li forming the inorganic content and bridged alkyl groups forming the organic content on the surface of the lithium-containing metal anode.

4. The altered SEI lithium anode of claim 2 or 3, wherein a composition of the artificial SEI on the surface of the lithium-containing metal anode is tuned, as compared to pristine Li, based on an altered -CH2- / COOH ratio in the dicarboxylic acid.

5. The altered SEI lithium anode of claim 4, wherein acid groups in the dicarboxylic acid react with Li to form a surface film on the surface of the anode, wherein the film comprises organic and inorganic salts of Li (e.g RCOOLi, (COOLi)2, Li2CO3, Li2O) and methylene groups.

6. The altered SEI lithium anode of any one of claims 1 to 5 , wherein the dicarboxylic acid comprises oxalic (OA), malonic (MA), succinic (SA), glutaric (GA), and adipic acid (AA).

7. The altered SEI lithium anode of any one of claims 1 to 6, wherein the artificial SEI comprises dicarboxylic acid modified Li selected from the group consisting of oxalic acid modified Li (OA-Li), malonic acid modified Li (MA-Li), succinic acid modified Li (SA- Li), glutaric acid modified Li (GA-Li), and adipic acid modified Li (AA-Li).Docket No. 1710.00065WO8. The altered SEI lithium anode of any one of claims 1 to 7, wherein the artificial SEI comprises a carbonate rich surface film formed from the dicarboxylic acid reacting with Li in the anode.

9. The altered SEI lithium anode of any one of claims 1 to 8, wherein the lithium- containing metal anode comprises a lithium-containing foil (e.g. LiMg foil, LiAl foil, LiAg foil, LiSn foil, and / or LiZn foil), a lithium metal foil, and / or a lithium alloy foil.

10. A method of making an altered SEI lithium anode of any one of claims 1 to 9, the method comprising exposing a lithium-containing metal anode to an acid solution comprising one or more dicarboxylic acids for a time sufficient to cause the formation of an artificial solid electrolyte interface (SEI) on a surface of the anode.

11. The method of claim 10, wherein the one or more dicarboxylic acids are selected from the group consisting of comprises oxalic (OA), malonic (MA), succinic (SA), glutaric (GA), and adipic acid (AA).

12. The method of claim 11, wherein the dicarboxylic acid is MA.

13. The method any one of claims 10 to 12, wherein the acid solution comprises a solvent, wherein the solution comprises about 5 % (W / W %) acid / solvent to about 20 % (W / W %) acid / solvent, optionally about 12 % (W / W %) acid / solvent, optionally wherein the solvent comprises Tetrahydro furan (THF), diethyl ether, dioxolane, ethers, esters, carbonates, and related polar aprotic solvents.

14. The method of any one of claims 10 to 13, wherein the lithium-containing metal anode is exposed to the acid solution for about 5 minutes to about 1 hour, optionally about 5 minutes, about 10 minutes, about 15 minutes, about 20 minutes, about 25 minutes, about 30 minutes, about 35 minutes, about 40 minutes, about 45 minutes, about 50 minutes, about 55 minutes, or about 60 minutes.

15. The method of any one of claims 10 to 14, wherein the method further comprises washing and / or drying the lithium-containing metal anode upon removal from the acid solution.

16. The method of any one of claims 10 to 15, further comprising selecting a carboxylic acid based on a ratio of methylene groups to carboxylic acid groups (i.e. -CH2- / COOH) inDocket No. 1710.00065WO the one or more dicarboxylic acids, optionally wherein the ratio of methylene groups to carboxylic acid groups is 0, 0.5, 1, 1.5, and 2 for oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid, respectively.

17. The method any one of claims 10 to 16, wherein formation of an artificial SEI on a surface of the anode comprises formation of a surface film comprising salts of Li forming the inorganic content and bridged alkyl groups forming the organic content on the surface of the lithium-containing metal anode.

18. The method of any one of claims 10 to 17, wherein a composition of the aritificial SEI on the surface of the lithium-containing metal anode is tuned, as compared to pristine Li, based on an altered -CH2- / COOH ratio in the dicarboxylic acid.

19. The method of any one of claims 10 to 18, wherein acid groups in the dicarboxylic acid react with Li to form a surface film on the surface of the anode, wherein the film comprises organic and inorganic salts of Li (e.g RCOOLi, (COOLih, Li2CO3, Li2O) and methylene groups.

20. The method of any one of claims 10 to 19, wherein the artificial SEI comprises dicarboxylic acid modified Li selected from the group consisting of oxalic acid modified Li (OA-Li), malonic acid modified Li (MA-Li), succinic acid modified Li (SA-Li), glutaric acid modified Li (GA-Li), and adipic acid modified Li (AA-Li).

21. The method of any one of claims 10 to 20, wherein the SEI comprises an altered surface structure and / or altered surface morphology as compared to a smooth uniform surface structure of pristine lithium.

22. An energy storage device, comprising an altered SEI lithium anode of any one of claims 1 to 9 or an altered SEI lithium anode made by the method any one of claims 10 to 21.

23. The energy storage device of claim 22, wherein the energy storage device substantially maintains a specific capacity and / or a voltage profile after a plurality of cycles, optionally wherein the specific capacity and / or the voltage profile are maintained at least about 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%,Docket No. 1710.00065WO88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% at the 100,hcycle as compared to a first cycle.

24. The energy storage device of claim 22 or 23, wherein the energy storage device comprises a battery, optionally a battery for an electric vehicle (EV).

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