Boron ester fluoranthene compounds, methods of making and using the same

Abstract

The present application relates to a kind of boron ester fluoranthene compound and its preparation method and application.The above-mentioned boron ester fluoranthene compound has the following general structure formula:Wherein, R1-R8 is independently selected from hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroalkyl, heterocyclyl, heteroaryl, amino, nitro, cyano, isocyan, halogen, alkylene, alkenylene, alkynylene, formyl, ester group one or more kinds;R9 is selected from alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroalkyl, heterocyclyl, heteroaryl, alkylene, alkenylene and alkynylene one kind.The above-mentioned boron ester fluoranthene compound is as a kind of solid-state fluorescent probe molecule, can specifically identify lithium fluoride component in SEI film.

Description

Technical Field

[0001] This invention relates to the field of batteries, and in particular to a boron ester fluoranthene compound, its preparation method, and its application. Background Technology

[0002] The solid electrolyte interphase (SEI) film at the negative electrode of a lithium-ion battery is an important electrode interface structure that directly affects the deposition behavior of lithium ions at the electrode interface. A stable and dense SEI film helps to suppress the growth of lithium dendrites at the negative electrode, thereby optimizing the cycle performance and lifespan of the lithium-ion battery.

[0003] SEI membranes contain a variety of chemical components, including inorganic lithium, organic lithium, and polymers, but lithium fluoride has attracted particular attention from researchers. Numerous studies have shown that a higher lithium fluoride content in the SEI membrane leads to greater stability and lithium-ion conductivity, thus significantly improving the cycle stability and safety of lithium batteries. Therefore, compared to other typical SEI membrane components such as lithium oxide, lithium chloride, and organic lithium, lithium fluoride has higher research value and application prospects.

[0004] Currently, the specific characterization of lithium fluoride components in SEI films mainly includes: 19 1F NMR spectroscopy (Nuclear Magnetic Resonance spectroscopy) and XPS spectroscopy (X-ray photoelectron spectroscopy) both obtain information about the electrode surface through the conversion of specific signals, enabling quantitative detection of lithium fluoride, but direct observation is difficult. Other methods, such as SEM (Scanning Electron Microscopy) and cryo-TEM (Cryo-Transmission Electron Microscopy), allow direct observation of the lithium fluoride structure, but these are limited by expensive experimental equipment and complex sample preparation procedures, and their quantification capabilities are relatively low.

[0005] Since 2022, the research team has used solid-state fluorescence technology to achieve a rough distinction between the SEI film and uneven lithium deposition (i.e., lithium dendrites), but it is still difficult to accurately identify and characterize the specific components inside the SEI film. Given the important role of lithium fluoride in the stability of the SEI film and the cycling performance of the lithium anode, it is necessary to develop and design a new class of solid-state fluorescent probe molecules for the specific identification of lithium fluoride components in the SEI film. Summary of the Invention

[0006] Based on this, a boron ester fluoranthene compound and its preparation method are provided. As a solid fluorescent probe molecule, it can specifically identify lithium fluoride components in SEI films in a simple and convenient way, realizing the visual observation and quantitative detection of lithium fluoride.

[0007] In addition, an application of boron ester fluoranthene compound in the detection of lithium fluoride in SEI membrane is also provided.

[0008] A boron ester fluoranthene compound has the following general structural formula:

[0009]

[0010] Among them, R1 to R8 are independently selected from hydrogen, C1 to C6, respectively. 10 Alkyl, C3-C 10 cycloalkyl, C2-C 10 alkenyl, C2-C 10 alkynyl group, C5-C 10 Aryl, C1-C 10 Heteroalkyl, C4-C 10 Heterocyclic group, C3-C 10 Heteroaryl, amino, nitro, cyano, isocyano, halogen, C1-C 10 Alkylene, C2-C 10 alkenyl, C2-C 10 One or more of the following: alkynyl, formyl, and ester group; R9 is selected from C1 to C2. 10 Alkyl, C3-C 10 cycloalkyl, C2-C 10 alkenyl, C2-C 10 alkynyl group, C5-C 10 Aryl, C1-C 10 Heteroalkyl, C4-C 10 Heterocyclic group, C3-C 10 heteroaryl, C1-C 10 Alkylene, C2-C 10 alkenyl groups and C2-C 10 One or more of the ethynyl groups.

[0011] In some embodiments, R1 to R8 are each independently selected from one or more of hydrogen, C1 to C6 alkyl, C2 to C6 alkenyl, C2 to C6 alkynyl, C1 to C6 heteroalkyl, amino, nitro, cyano, isocyano, halogen, C1 to C6 alkylene, C2 to C6 alkenyl, C2 to C6 alynyl, formyl, and ester, and R9 is selected from one or more of C3 to C6 cycloalkyl, C5 to C6 aryl, C4 to C6 heterocyclic, and C3 to C6 heteroaryl.

[0012] In some embodiments, the structural formula of the boron ester fluoranthene compound is as follows:

[0013] A method for preparing a boron ester fluoranthene compound includes the following steps:

[0014] Compound 1 was reacted with boron tribromide to prepare compound 2. The structural formula of compound 1 is as follows: The structural formula of compound 2 is as follows: R1 to R8 are each independently selected from hydrogen, C1 to C8. 10 Alkyl, C3-C 10 cycloalkyl, C2-C 10 alkenyl, C2-C 10 alkynyl group, C5-C 10 Aryl, C1-C 10 Heteroalkyl, C4-C 10 Heterocyclic group, C3-C 10 Heteroaryl, amino, nitro, cyano, isocyano, halogen, C1-C 10 Alkylene, C2-C 10 alkenyl, C2-C 10 One or more of the following: ynyl group, formyl group, and ester group;

[0015] The compound 2 was reacted with R9-B(OH)2 to prepare a boron ester fluoranthene compound, wherein R9 was selected from C1 to C2. 10 Alkyl, C3-C 10 cycloalkyl, C2-C 10 alkenyl, C2-C 10 alkynyl group, C5-C 10 Aryl, C1-C 10 Heteroalkyl, C4-C 10 Heterocyclic group, C3-C 10 heteroaryl, C1-C 10 Alkylene, C2-C 10 alkenyl groups and C2-C 10 One or more of the alkynyl groups, wherein the structural formula of the boron ester fluoranthene compound is as follows:

[0016] In some embodiments, the step of reacting compound 1 with boron tribromide includes: adding an anhydrous dichloromethane solution containing boron tribromide to an anhydrous dichloromethane solution containing compound 1 at -78°C to -20°C, and after the addition is completed, heating to 10°C to 30°C and reacting for 24h to 48h.

[0017] In some embodiments, the step of reacting compound 2 with R9-B(OH)2 includes: mixing compound 2 and R9-B(OH)2 in anhydrous tetrahydrofuran and shaking at 10°C to 30°C for 10 min to 60 min.

[0018] The application of a boron ester fluoranthene compound in the detection of lithium fluoride in a solid electrolyte interfacial membrane, wherein the boron ester fluoranthene compound is the boron ester fluoranthene compound described above or a boron ester fluoranthene compound prepared by the above preparation method.

[0019] In some embodiments, the following steps are included:

[0020] A lithium battery is provided, wherein a solid electrolyte interface film is formed on the surface of the lithium metal negative electrode;

[0021] A solution containing the boron ester fluoranthene compound is attached to the surface of the lithium metal anode where a solid electrolyte interface film is formed.

[0022] The lithium metal anode is irradiated with an excitation light source to obtain fluorescence information on the surface of the lithium metal anode.

[0023] Lithium fluoride in the solid electrolyte interface membrane is detected based on the fluorescence information.

[0024] In some embodiments, the step of irradiating the lithium metal anode with an excitation light source to obtain fluorescence information on the surface of the lithium metal anode satisfies at least one of the following conditions:

[0025] (1) Observe the fluorescence on the surface of the lithium metal anode directly under a handheld ultraviolet light;

[0026] (2) The surface of the lithium metal anode was observed or photographed under a fluorescence microscope with high resolution;

[0027] (3) The surface of the lithium metal anode was analyzed using a fluorescence spectrometer.

[0028] In some embodiments, the step of detecting lithium fluoride in the solid electrolyte interface film based on the fluorescence information satisfies at least one of the following conditions:

[0029] (1) Determine whether the solid electrolyte interface film contains lithium fluoride based on the fluorescence color;

[0030] (2) Determine the distribution of lithium fluoride in the solid electrolyte interface film based on the fluorescence signal distribution;

[0031] (3) The content of lithium fluoride in the solid electrolyte interface film was quantitatively analyzed based on the fluorescence intensity.

[0032] In some embodiments, the solution containing the boron ester fluoranthene compound satisfies at least one of the following conditions:

[0033] (1) The concentration of the solution containing the boron ester fluoranthene compound is 0.5 mg / mL to 5 mg / mL;

[0034] (2) The solvent used in the solution containing the boron ester fluoranthene compound includes any one or more of diethyl ether, tetrahydrofuran, acetone, n-hexane and cyclohexane.

[0035] In some embodiments, the lithium battery includes any one or more of lithium symmetric batteries, lithium-sulfur batteries, lithium-oxygen batteries, lithium-air batteries, and lithium-oxide batteries.

[0036] The fluoranthracene structure in the aforementioned boron ester fluoranthracene compounds exhibits strong photoluminescence properties in both solution and aggregated states (solid or poor solvents), emitting fluorescence signals upon excitation by ultraviolet light. The boron ester structure in these compounds possesses empty 2p orbitals, resulting in localized electron deficiency and making it a typical coordination acceptor. When reacting with lithium fluoride, fluoride ions effectively act as electron-rich coordinating species, forming a luminescent four-coordinate boron compound. This leads to significant changes in the electron distribution and orbital energy of the boron ester fluoranthracene compound, exhibiting a dual responsiveness in both fluorescence intensity and wavelength, thus enabling rapid response and detection of lithium fluoride. However, when the boron ester fluoranthracene compound interacts with other typical components in the SEI film, such as lithium oxide and lithium acetate, it is difficult to effectively form coordination bonds, thus retaining its intrinsic fluorescence signal. Based on the differences in fluorescence signals and intensities between the two compounds, visual observation and quantitative analysis of the lithium fluoride component in the SEI film can be achieved. Attached Figure Description

[0037] Figure 1 The following are synthetic routes for phenylboronic fluoranthene in some embodiments;

[0038] Figure 2 This is a schematic diagram of the process flow for the application of boron ester fluoranthene compounds in the detection of lithium fluoride in solid electrolyte interface membranes in some embodiments.

[0039] Figure 3 This is a schematic diagram illustrating the fluorescence changes and mechanism after coordination of phenylboronic fluoranthene with lithium fluoride.

[0040] Figure 4 The MALDI-TOF MS mass spectrum of phenylboronic fluoranthene ester is shown.

[0041] Figure 5 The fluorescence spectra of the phenylboronic fluoranthene ester prepared in Example 1 before and after reaction with lithium fluoride are excited by a 365 nm ultraviolet lamp.

[0042] Figure 6 The fluorescence emission intensity and photographs of phenylborane fluoranthene reacting with typical components of the SEI membrane;

[0043] Figure 7 Image and distribution of lithium fluoride on the surface of lithium anode sheets in Examples 2 and 3, for phenylborane fluoranthene. Detailed Implementation

[0044] To facilitate understanding of the present invention, a more comprehensive description of the invention will be provided below in conjunction with specific embodiments. Preferred embodiments of the invention are given in the specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0046] Unless otherwise stated or in case of contradiction, the terms or phrases used in this invention shall have the following meanings:

[0047] In this invention, "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include at least one of those features.

[0048] In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0049] In this invention, "one or several" refers to any one, any two, or any two or more of the listed items. "Several" refers to any two or more.

[0050] In this invention, unless otherwise specified, all percentage concentrations refer to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of that component.

[0051] The terms "preferred," "more preferably," etc., used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0052] When a numerical range is disclosed in this invention, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Further, when the range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Moreover, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed in this invention should be understood to include any and all subranges to which they are incorporated.

[0053] In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0054] The terms "comprising" and "having," and any variations thereof, used in embodiments of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or components inherent to such processes, methods, products, or devices.

[0055] In this invention, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0056] The term "alkyl" refers to a saturated hydrocarbon containing a primary (normal) carbon atom, or a secondary carbon atom, or a tertiary carbon atom, or a quaternary carbon atom, or a combination thereof. Phrases containing this term include, for example, "C1-C1...". 10 "Alkyl" refers to an alkyl group containing 1 to 10 carbon atoms. Each time it appears, it can independently be C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, C7 alkyl, C8 alkyl, C9 alkyl, or C 10Alkyl groups. Suitable examples include, but are not limited to: methyl (Me, -CH3), ethyl (Et, -CH2CH3), 1-propyl (n-Pr, n-propyl, -CH2CH2CH3), 2-propyl (i-Pr, i-propyl, -CH(CH3)2), 1-butyl (n-Bu, n-butyl, -CH2CH2CH2CH3), 2-methyl-1-propyl (i-Bu, i-butyl, -CH2CH(CH3)2), 2-butyl (s-Bu, s-butyl, -CH(C H3)CH2CH3), 2-methyl-2-propyl (t-Bu, t-butyl, -C(CH3)3), 1-pentyl (n-pentyl, -CH2CH2CH2CH2CH3), 2-pentyl (-CH(CH3)CH2CH2CH3), 3-pentyl (-CH(CH2CH3)2), 2-methyl-2-butyl (-C(CH3)2CH2CH3), 3-methyl-2-butyl (-CH(CH3)CH(CH3)2), 3-methyl-1-butyl (- CH2CH2CH(CH3)2), 2-methyl-1-butyl(-CH2CH(CH3)CH2CH3), 1-hexyl(-CH2CH2CH2CH2CH2CH3), 2-hexyl(-CH(CH3)CH2CH2CH2CH3), 3-hexyl(-CH(CH2CH3)(CH2CH2CH3)), 2-methyl-2-pentyl(-C(CH3)2CH2CH2CH3), 3-methyl-2-pentyl(-CH(CH3)CH( CH3)CH2CH3), 4-methyl-2-pentyl (-CH(CH3)CH2CH(CH3)2), 3-methyl-3-pentyl (-C(CH3)(CH2CH3)2), 2-methyl-3-pentyl (-CH(CH2CH3)CH(CH3)2), 2,3-dimethyl-2-butyl (-C(CH3)2CH(CH3)2), 3,3-dimethyl-2-butyl (-CH(CH3)C(CH3)3 and octyl (-(CH2)7CH3).

[0057] The term "cycloalkyl" refers to a non-aromatic hydrocarbon containing a ring of carbon atoms, which can be monocycloalkyl, spirocycloalkyl, or bridged cycloalkyl. Phrases containing this term include, for example, "C3-C...". 10 "Cycloalkyl" refers to a cycloalkyl group containing 3 to 10 carbon atoms. Each time it appears, it can independently be C3 cycloalkyl, C4 cycloalkyl, C5 cycloalkyl, C6 cycloalkyl, C7 cycloalkyl, C8 cycloalkyl, C9 cycloalkyl, or C6 cycloalkyl. 10 Cycloalkyl. Suitable examples include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl. Additionally, "cycloalkyl" may contain one or more double bonds; representative examples of cycloalkyl groups containing double bonds include cyclopentenyl, cyclohexenyl, cyclohexadienyl, and cyclobutadienyl.

[0058] "Alkenyl" refers to a group containing at least one unsaturated site, i.e., carbon-carbon sp. 2 Hydrocarbons with double bonds consisting of a positive, secondary, tertiary carbon atom, or a cyclic carbon atom. Phrases containing this term, such as "C2~C2". 10 "Alkenyl" refers to an alkenyl group containing 2 to 10 carbon atoms. Each time it appears, it can independently be C2 alkenyl, C3 alkenyl, C4 alkenyl, C5 alkenyl, C6 alkenyl, C7 alkenyl, C8 alkenyl, C9 alkenyl, or C... 10 Alkenyl. Suitable examples include, but are not limited to: vinyl (-CH=CH2), allyl (-CH2CH=CH2), cyclopentenyl (-C5H7) and 5-hexenyl (-CH2CH2CH2CH2CH=CH2).

[0059] "Alynyl" refers to a hydrocarbon containing at least one unsaturated carbon atom, namely a carbon-carbon sp triple bond, or a cyclic carbon atom. Phrases containing this term include, for example, "C2~C...". 10 "Alynyl" refers to an alkynyl group containing 2 to 9 carbon atoms. Each time it appears, it can independently be C2-alkynyl, C3-alkynyl, C4-alkynyl, C5-alkynyl, C6-alkynyl, C7-alkynyl, C8-alkynyl, C9-alkynyl, or C... 10 Alkyne group. Suitable examples include, but are not limited to: ethynyl (-C≡CH) and propyne (-CH2C≡CH).

[0060] "Aryl" refers to an aromatic hydrocarbon group derived from an aromatic ring compound by removing one hydrogen atom. It can be a monocyclic aryl, a fused-ring aryl, or a polycyclic aryl. For polycyclic compounds, at least one ring must be an aromatic ring system. For example, "C5~C5..." 10 "Aryl" refers to an aryl group containing 5 to 10 carbon atoms. Each time it appears, it can independently be C5 aryl, C6 aryl, C8 aryl, C6 aryl, C7 aryl, C8 aryl, C9 ... 10 Aryl group. Suitable examples include, but are not limited to: benzene, biphenyl, naphthalene, anthracene, phenanthrene, dinaphthalene, triphenylene and their derivatives. Understandably, multiple aryl groups may also be interrupted by short non-aromatic units (e.g., <10% non-H atoms, such as C, N or O atoms), specifically acenaphthene, fluorene, or 9,9-diarylfluorene, triarylamines, and diaryl ether systems should also be included in the definition of aryl.

[0061] "Heteroaryl" refers to an aryl group in which at least one carbon atom is replaced by a non-carbon atom, which can be a nitrogen atom, an oxygen atom, a sulfur atom, etc. For example, "C3~C 10"Heteroaryl" refers to a heteroaryl group containing 3 to 10 carbon atoms, which can be independently C3, C4, C5, C6, C7, or C8 heteroaryl each time it appears. Suitable examples include, but are not limited to: furan, benzofuran, thiophene, benzothiophene, pyrrole, pyrazole, triazole, imidazole, oxazole, oxadiazole, thiazole, tetrazolium, indole, carbazole, pyrroloimidazol, pyrrolopyrrole, thiophenolopyrrole, thiophenolothiophene, furanolopyrrole, furanolofuran, thiophenolofuran, benzoisoxazole, benzoisothiazolium, benzimidazole, pyridine, pyrazine, pyridazine, pyrimidine, triazine, quinoline, isoquinoline, o-diazonyl, quinoxaline, phenanthridine, primidine, quinazoline, and quinazolineone.

[0062] "Heteroalkyl" refers to an alkyl group in which at least one carbon atom is replaced by a non-carbon atom, such as a nitrogen (N), oxygen (O), sulfur (S), etc. For example, if a carbon atom in an alkyl group is replaced by a non-carbon atom, the resulting heteroalkyl group is an alkoxy group (e.g., -OCH3), an amine (e.g., -NHCH3, -N(CH3)2), or a thioalkyl group (e.g., -SCH3). If no carbon atom in an alkyl group is replaced by a non-carbon atom, the resulting heteroalkyl group is an alkyl ether (e.g., -CH2CH2-O-CH3), an alkylamine (e.g., -CH2NHCH3, -CH2N(CH3)2), or a thioalkyl ether (e.g., -CH2-S-CH3). If the terminal carbon atom of an alkyl group is replaced by a non-carbon atom, the resulting heteroalkyl group is a hydroxyalkyl group (e.g., -CH2CH2-OH), an aminoalkyl group (e.g., -CH2NH2), or an alkyl mercapto group (e.g., -CH2CH2-SH). Phrases containing the term, such as "C1~C 10 "Heteroalkyl" refers to a heteroalkyl group containing 1 to 10 carbon atoms. Each time it appears, it can independently be a C2 heteroalkyl, C3 heteroalkyl, C4 heteroalkyl, C5 heteroalkyl, C7 heteroalkyl, C8 heteroalkyl, C9 heteroalkyl, or C 10 Heteroalkyl groups.

[0063] "Heterocyclic group" refers to a cycloalkyl group in which at least one carbon atom is replaced by a non-carbon atom. The non-carbon atom can be a nitrogen atom, an oxygen atom, a sulfur atom, etc., and can be a saturated ring or a partially unsaturated ring. Phrases containing this term include, for example, "C4~C5". 10 A "heterocyclic group" refers to a heterocyclic group containing 4 to 10 carbon atoms. Each time it appears, it can be independently a C4 heterocyclic group, a C5 heterocyclic group, a C6 heterocyclic group, a C7 heterocyclic group, a C8 heterocyclic group, a C9 heterocyclic group, or a C10 heterocyclic group. 10Heterocyclic groups. Suitable examples include, but are not limited to: dihydropyridyl, tetrahydropyridyl (piperidinyl), tetrahydrothiophenyl, sulfur-oxidized tetrahydrothiophenyl, tetrahydrofuranyl, tetrahydroquinolinyl, tetrahydroisoquinolinyl, and dihydroindolyl.

[0064] "Amino" refers to a derivative of ammonia, possessing the structural characteristic of the formula -N(X)2, where each "X" is independently H, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted heterocyclic group, etc. Non-limiting types of amino groups include -NH2, -N(alkyl)2, -NH(alkyl), -N(cycloalkyl)2, -NH(cycloalkyl), -N(heterocyclic)2, -NH(heterocyclic), -N(aryl)2, -NH(aryl), -N(alkyl)(aryl), -N(alkyl)(heterocyclic), -N(cycloalkyl)(heterocyclic), -N(aryl)(heteroaryl), -N(alkyl)(heteroaryl), etc.

[0065] "Halogen" or "halogen group" refers to F, Cl, Br or I.

[0066] "Alkylene" refers to a hydrocarbon group derived from an alkyl group by removing one hydrogen atom, forming a group with two monovalent groups at its center. It can be a saturated branched alkyl group or a saturated straight-chain alkyl group. For example, "C1~C1..." 10 "Alkylene" refers to an alkyl group containing 1 to 10 carbon atoms, and each occurrence can independently be C1 alkylene, C4 alkylene, C5 alkylene, C6 alkylene, C7 alkylene, C8 alkylene, C9 alkylene, C1 alkylene, C2 alkylene, C3 ... 10 Alkylene. Suitable examples include, but are not limited to: methylene (-CH2-), 1,1-ethyl (-CH(CH3)-), 1,2-ethyl (-CH2CH2-), 1,1-propyl (-CH(CH2CH3)-), 1,2-propyl (-CH2CH(CH3)-), 1,3-propyl (-CH2CH2CH2-), and 1,4-butyl (-CH2CH2CH2CH2-).

[0067] "Alkenyl" refers to a hydrocarbon group derived from an alkenyl group by removing one hydrogen atom, forming a group with two monovalent groups at its center. It can be an unsaturated branched hydrocarbon group or an unsaturated straight-chain hydrocarbon group. For example, "C2~C 10 "Alkenyl" refers to an alkenyl moiety containing 2 to 10 carbon atoms, and each occurrence can be independently C2-alkenyl, C4-alkenyl, C5-alkenyl, C6-alkenyl, C7-alkenyl, C8-alkenyl, C9-alkenyl, or C... 10 Alkenyl groups. Suitable examples include, but are not limited to, 1,2-vinyl (-CH=CH-).

[0068] "Alynyl group" refers to a hydrocarbon group derived from an alkynyl group by removing one hydrogen atom, forming a group with two monovalent groups. It can be an unsaturated branched hydrocarbon group or an unsaturated straight-chain hydrocarbon group. For example, "C2~C 10 "Imyynyl" refers to an alkynyl moiety containing 2 to 10 carbon atoms. Each time it appears, it can independently be C2-Imyynyl, C4-Imyynyl, C5-Imyynyl, C6-Imyynyl, C7-Imyynyl, C8-Imyynyl, C9-Imyynyl, or C... 10 Alkenyne group. Suitable examples include, but are not limited to: ethynyl (-C≡C-), propyne (-CH2C≡C-), and 4-pentynyl (-CH2CH2CH2C≡C-).

[0069] As described in the background section, lithium fluoride has higher research value and application prospects compared to other typical components in SEI films, such as lithium oxide, lithium chloride, and organolithium compounds. However, traditional methods for characterizing lithium fluoride components are insufficient to simultaneously achieve both visual observation and quantitative detection of lithium fluoride within the SEI film, and these methods have relatively low experimental requirements and are simple and convenient to operate. Although solid-state fluorescence technology can roughly distinguish between the SEI film and non-uniform lithium deposition (i.e., lithium dendrites), it remains difficult to accurately identify and characterize specific components within the SEI film.

[0070] Based on this, the present invention provides a boron ester fluoranthene compound that can specifically recognize lithium fluoride components in SEI films. Specifically, the general structural formula of the boron ester fluoranthene compound is as follows:

[0071]

[0072] Among them, R1 to R8 are independently selected from C1 to C2. 10 Alkyl, C3-C 10 cycloalkyl, C2-C 10 alkenyl, C2-C 10 alkynyl group, C5-C 10 Aryl, C1-C 10 Heteroalkyl, C4-C 10 Heterocyclic group, C3-C 10 Heteroaryl, amino, nitro, cyano, isocyano, halogen, C1-C 10 Alkylene, C2-C 10 alkenyl, C2-C 10 One or more of the following: alkynyl, formyl, and ester group; R9 is selected from C1 to C2. 10 Alkyl, C3-C 10 cycloalkyl, C2-C 10 alkenyl, C2-C 10 alkynyl group, C5-C 10 Aryl, C1-C 10 Heteroalkyl, C4-C10 Heterocyclic group, C3-C 10 heteroaryl, C1-C 10 Alkylene, C2-C 10 alkenyl groups and C2-C 10 One or more of the ethynyl groups.

[0073] Without altering the aforementioned structure, by modifying fluoranthene R1–R8 or borate ester R9 with different numbers and types of substituents, controllable modulation of the fluorescence signal wavelength and intensity can be achieved.

[0074] In some embodiments, R1 to R8 are each independently selected from one or more of C1-C6 alkyl, C3-C6 cycloalkyl, C2-C6 alkenyl, C2-C6 alkynyl, C5-C6 aryl, C1-C6 heteroalkyl, C4-C6 heterocyclic, C3-C6 heteroaryl, amino, nitro, cyano, isocyano, halogen, C1-C6 alkylene, C2-C6 alkenyl, C2-C6 alynyl, formyl, and ester; R9 is selected from one or more of C1-C6 alkyl, C3-C6 cycloalkyl, C2-C6 alkenyl, C2-C6 alkynyl, C5-C6 aryl, C1-C6 heteroalkyl, C4-C6 heterocyclic, C3-C6 heteroaryl, C1-C6 alkylene, C2-C6 alkenyl, and C2-C6 alynyl.

[0075] In some embodiments, R1 to R8 are each independently selected from one or more of hydrogen, C1 to C6 alkyl, C2 to C6 alkenyl, C2 to C6 alkynyl, C1 to C6 heteroalkyl, amino, nitro, cyano, isocyano, halogen, C1 to C6 alkylene, C2 to C6 alkenyl, C2 to C6 alynyl, formyl, and ester, and R9 is selected from one or more of C3 to C6 cycloalkyl, C5 to C6 aryl, C4 to C6 heterocyclic, and C3 to C6 heteroaryl. Furthermore, R1 to R8 are each independently selected from one or more of hydrogen, C1 to C3 alkyl, C2 to C3 alkenyl, C2 to C3 alkynyl, C1 to C3 heteroalkyl, amino, nitro, cyano, isocyano, halogen, C1 to C3 alkylene, C2 to C3 alkenyl, C2 to C3 alynyl, formyl, and ester, and R9 is selected from one or more of C3 to C6 cycloalkyl, C5 to C6 aryl, C4 to C6 heterocyclic, and C3 to C6 heteroaryl.

[0076] In some embodiments, R1 to R8 are each independently selected from one or more of hydrogen, C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, and C1-C6 heteroalkyl, and R9 is selected from one or more of C3-C6 cycloalkyl, C5-C6 aryl, C4-C6 heterocyclic, and C3-C6 heteroaryl. Further, R1 to R8 are each independently selected from one or more of hydrogen, C1-C3 alkyl, C2-C3 alkenyl, C2-C3 alkynyl, and C1-C3 heteroalkyl, and R9 is selected from one or more of C3-C6 cycloalkyl, C5-C6 aryl, C4-C6 heterocyclic, and C3-C6 heteroaryl.

[0077] In some embodiments, R1 to R8 are all hydrogen, and R9 is selected from one or more of C3-C6 cycloalkyl, C5-C6 aryl, C4-C6 heterocyclic, and C3-C6 heteroaryl. Further, R1 to R8 are all hydrogen, and R9 is selected from one or more of C5-C6 aryl and C3-C6 heteroaryl.

[0078] In one embodiment, R1 to R8 are all hydrogen, R9 is phenyl, and the structural formula of the boron ester fluoranthene compound is as follows: In another embodiment, R1 to R8 are all hydrogen, R9 is pyridine, and the structural formula of the boron ester fluoranthene compound is as follows:

[0079] The aforementioned boron ester fluoranthene compounds exhibit strong photoluminescence properties in both solution and aggregated states (solid or poor solvents), emitting fluorescence signals upon ultraviolet light excitation. The boron ester structure in these compounds possesses empty 2p orbitals, resulting in localized electron deficiency and making it a typical coordination acceptor. When reacting with lithium fluoride, fluoride ions effectively act as electron-rich coordinating species, forming a luminescent four-coordinate boron compound with the boron ester fluoranthene. This leads to significant changes in the electron distribution and orbital energy of the boron ester fluoranthene, resulting in a dual response in both fluorescence signal intensity and wavelength, thus enabling rapid response and detection of lithium fluoride. However, when boron ester fluoranthene interacts with other typical components in the SEI film, such as lithium oxide and lithium acetate, it is difficult to form effective coordination bonds, thus retaining its intrinsic fluorescence signal. Based on the difference in fluorescence signals between the two compounds, specific analysis of lithium fluoride components in the SEI film can be achieved.

[0080] A second aspect of the present invention provides a method for preparing a boron ester fluoranthene compound, comprising the following steps;

[0081] Step S110: React compound 1 with boron tribromide to obtain compound 2.

[0082] The structural formula of compound 1 is as follows: The structural formula of compound 2 is R1 to R8 are each independently selected from hydrogen, C1 to C8.10 Alkyl, C3-C 10 cycloalkyl, C2-C 10 alkenyl, C2-C 10 alkynyl group, C5-C 10 Aryl, C1-C 10 Heteroalkyl, C4-C 10 Heterocyclic group, C3-C 10 Heteroaryl, amino, nitro, cyano, isocyano, halogen, C1-C 10 Alkylene, C2-C 10 alkenyl, C2-C 10 One or more of the following: alkyne group, formyl group, and ester group.

[0083] In some embodiments, step S110 includes: adding an anhydrous dichloromethane solution containing boron tribromide to an anhydrous dichloromethane solution containing compound 1 at -78°C to -20°C; after the addition is complete, heating to room temperature and reacting for 24 h to 48 h. After the reaction is complete, quenching the reaction with ice water, collecting the organic phase, drying, and removing the solvent to obtain compound 2. In this document, room temperature refers to a temperature of 10°C to 30°C, for example, a temperature of 10°C, 12°C, 15°C, 18°C, 20°C, 22°C, 25°C, 28°C, 30°C, or any combination of these values, such as 20°C to 25°C.

[0084] It is understood that the above provides a relatively specific reaction of compound 1 with boron tribromide, but it is not limited to this and can be adjusted according to the steps of the reaction of boron tribromide with methoxy groups commonly used in the art.

[0085] Step S120: Compound 2 is reacted with R9-B(OH)2 to obtain boron ester fluoranthene compound.

[0086] Among them, R9 is selected from C1 to C2. 10 Alkyl, C3-C 10 cycloalkyl, C2-C 10 alkenyl, C2-C 10 alkynyl group, C5-C 10 Aryl, C1-C 10 Heteroalkyl, C4-C 10 Heterocyclic group, C3-C 10 heteroaryl, C1-C 10 Alkylene, C2-C 10 alkenyl groups and C2-C 10 One of the alkyne groups, the structural formula of the boron ester fluoranthene compound is as follows:

[0087]

[0088] In some embodiments, step S120 includes: mixing compound 2 with R9-B(OH)2 in anhydrous tetrahydrofuran solution, shaking at room temperature for 10 min to 60 min, and then removing the tetrahydrofuran to obtain boron ester fluoranthene compound.

[0089] In some embodiments, the boron ester fluoranthene compound is phenylboron ester fluoranthene, and its synthetic route is as follows: Figure 1 As shown.

[0090] The preparation method of the above-mentioned boron ester fluoranthene compounds is simple and has a high yield.

[0091] A third aspect of the present invention provides the application of boron ester fluoranthene compounds in the detection of lithium fluoride in solid electrolyte interfacial membranes.

[0092] Specifically, please refer to Figure 2 It includes the following steps:

[0093] Step S210: Provide a lithium battery, wherein a solid electrolyte interface film is formed on the surface of the lithium metal negative electrode of the lithium battery.

[0094] In some embodiments, a lithium battery includes any battery with lithium metal as the negative electrode. For example, a lithium battery includes any one or more of lithium-sulfur batteries, lithium-oxygen batteries, lithium-air batteries, and lithium-oxide batteries.

[0095] In some embodiments, a solid electrolyte film is formed on the surface of the lithium metal anode by charging and discharging the lithium battery. The specific charge-discharge cycles are not particularly limited and can be those commonly used in the art, and will not be elaborated further.

[0096] Step S220: A solution containing boron ester fluoranthene compound is attached to the surface of the lithium metal anode where a solid electrolyte interface film is formed.

[0097] In some embodiments, the solvent used for the solution containing the boron ester fluoranthene compound includes any one or more of diethyl ether, tetrahydrofuran, acetone, n-hexane, and cyclohexane. These solvents are inert and volatile.

[0098] In some embodiments, the concentration of the solution containing boron ester fluoranthene compound is from 0.5 mg / mL to 5 mg / mL. For example, the concentration of the solution containing boron ester fluoranthene compound may be, but is not limited to, 0.5 mg / mL, 1 mg / mL, 1.5 mg / mL, 2 mg / mL, 2.5 mg / mL, 3 mg / mL, 3.5 mg / mL, 4 mg / mL, 4.5 mg / mL, 5 mg / mL, or any range of these values. Preferably, in some embodiments, the concentration of the solution containing boron ester fluoranthene compound is 1 mg / mL. Within the above concentration range, detection accuracy can be further improved.

[0099] Step S230: Irradiate the lithium metal anode with an excitation light source to obtain fluorescence information on the surface of the lithium metal anode.

[0100] In some embodiments, the step of irradiating the lithium metal anode with an excitation light source to obtain fluorescence information on the surface of the lithium metal anode satisfies at least one of the following conditions:

[0101] (1) Observe the fluorescence on the surface of the lithium metal anode under a handheld ultraviolet light;

[0102] (2) High-resolution observation or imaging of the lithium metal anode surface under a fluorescence microscope;

[0103] (3) The surface of the lithium metal anode was analyzed using a fluorescence spectrometer.

[0104] In some embodiments, the handheld ultraviolet lamp has a wavelength of 365 nm. The fluorescence of the lithium metal anode surface, such as its color and distribution, can be directly observed with the naked eye using this handheld ultraviolet lamp. High-resolution observation using a fluorescence microscope allows for visual analysis of the specific distribution differences and morphology of lithium fluoride. The fluorescence intensity of the lithium metal anode surface can be measured using a fluorescence spectrometer.

[0105] Step S240: Detect lithium fluoride in the solid electrolyte interface film based on fluorescence information.

[0106] In some embodiments, the step of detecting lithium fluoride in the solid electrolyte interface membrane based on fluorescence information satisfies at least one of the following conditions:

[0107] (1) Determine whether the solid electrolyte interface film contains lithium fluoride based on the fluorescence color;

[0108] (2) Determine the distribution of lithium fluoride in the solid electrolyte interface film based on the fluorescence signal distribution;

[0109] (3) The content of lithium fluoride in the solid electrolyte interface film was quantitatively analyzed based on the difference in fluorescence intensity.

[0110] Fluoranthene molecules exhibit strong photoluminescence properties in both solution and aggregated states (solid or in poor solvents), emitting fluorescent signals upon excitation by ultraviolet light. Boron ester fluoranthene, with its boron ester structure possessing empty 2p orbitals and locally electron-deficient, acts as a typical coordination acceptor. When reacting with lithium fluoride, fluoride ions effectively act as electron-rich coordinating species, forming a luminescent four-coordinate boron compound with the boron ester fluoranthene. This leads to significant changes in the electron distribution and orbital energy of the boron ester fluoranthene, resulting in a dual response in both fluorescence signal intensity and wavelength, thus enabling rapid response and detection of lithium fluoride. However, when boron ester fluoranthene interacts with other typical components in SEI films, such as lithium oxide and lithium acetate, it is difficult to form effective coordination bonds, thus retaining its intrinsic fluorescence signal. Based on the difference in fluorescence signals between the two, specific analysis of lithium fluoride components can be achieved.

[0111] Taking phenylboronic fluoranthene as an example, the schematic diagram is as follows: Figure 3 As shown.

[0112] The above-mentioned boron ester fluoranthene compounds have at least the following advantages in the application of detecting lithium fluoride components in solid electrolyte interfacial membranes:

[0113] (1) The above application uses boron ester fluoranthene compounds as chemical probes and utilizes solid-state fluorescence technology to detect lithium fluoride components in the SEI film. Boron ester fluoranthene only shows a significant difference in fluorescence signal before and after interaction with lithium fluoride, while no fluorescence change occurs when interacting with other typical components or byproducts of the SEI film. Based on the above principle, not only can the regional distribution and relative abundance of lithium fluoride components in the SEI film be quantitatively and visually identified, but the characterization results of lithium fluoride can also be linked to the stability, compactness, and cycling performance of the electrode interface, thus providing a new approach and direction for evaluating the state of the electrode interface and the growth of the SEI film.

[0114] (2) The above applications have the advantages of being simple and convenient, highly sensitive, highly accurate and widely applicable.

[0115] To make the objectives and advantages of the present invention clearer, the boron ester fluoranthene compound and its effects of the present invention are further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and should not be used to limit the present invention. Unless otherwise specified, the following embodiments do not include components other than unavoidable impurities. Unless otherwise specified, the drugs and instruments used in the embodiments are conventional choices in the art. Experimental methods in the embodiments that do not specify specific conditions were implemented according to conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer.

[0116] Example 1

[0117] This embodiment provides a boron ester fluoranthene compound with the following structure: The preparation process is as follows:

[0118] 1 g of boron tribromide was dissolved in 5 mL of anhydrous dichloromethane to prepare a solution for later use. Separately, 262.3 mg of dimethoxyfluoranthracene (CAS No. 947409-79-2) was dissolved in 5 mL of anhydrous dichloromethane, and the solution was cooled to -78 °C in a liquid nitrogen bath. The boron tribromide solution was then slowly added dropwise at this temperature, completing the addition within 10 minutes. The mixture was then brought to room temperature and stirred for 24 hours. After the reaction was complete, 20 mL of ice water was slowly added to quench the reaction. After thorough mixing, the lower dichloromethane solution was separated, dried with a small amount of anhydrous sodium sulfate powder, and then evaporated under vacuum to obtain 220 mg of dihydroxyfluoranthracene, with a yield of 93.9%.

[0119] 220 mg of dihydroxyfluoranthene was dissolved in 5 mL of anhydrous tetrahydrofuran, and 114.5 mg of phenylboronic acid was added at a stoichiometric ratio of 1:1. The mixture was shaken thoroughly at room temperature for 10 minutes to obtain the target product solution. After vacuum evaporation, the target product powder was obtained with a yield of 99.9%.

[0120] Figure 4 This is a MALDI-TOF MS (matrix-assisted laser desorption / ionization time-of-flight mass spectrometry) spectrum of the boron ester fluoranthene prepared in Example 1. Figure 4 It can be seen that the mass-to-charge ratio of the final product in Example 1 is 320.1582 (i.e., Found: 320.1582 in the figure); the theoretical mass-to-charge ratio of the target product phenylboron fluoranthene is 320.1009 (i.e., Calcd: 320.1009 in the figure), which effectively proves that the final product is phenylboron fluoranthene.

[0121] Figure 5 The figures show the fluorescence spectra of the phenylboronic fluoranthene prepared in Example 1 before and after reaction with lithium fluoride, under 365 nm UV excitation. As can be seen from the figures, the phenylboronic fluoranthene probe molecule exhibits yellow fluorescence emission in the solid state under 365 nm UV excitation, with a maximum emission wavelength of 549 nm. However, the product after coordination with lithium fluoride—fluoranthene fluoride fluoropolymer—exhibits orange fluorescence emission under 365 nm UV excitation, with a maximum emission wavelength red-shifted to 575 nm and a response shift (Δλ) of 26 nm.

[0122] Figure 6 The images show the fluorescence emission intensity and photographs of phenylboronic fluoranthene reacting with typical components of the SEI membrane. Both solution-state and solid-state lithium fluoride induce a fluorescence shift response in phenylboronic fluoranthene, while it retains its intrinsic yellow fluorescence signal after reacting with lithium oxide, lithium chloride, or lithium acetate. Other common components in the SEI membrane do not elicit a response from phenylboronic fluoranthene, indicating that this probe exhibits a specific response to lithium fluoride.

[0123] Example 2

[0124] The lithium metal battery used was a Li|Li symmetrical coin cell, with lithium plates as both positive and negative electrodes. The electrolyte contained 1 mol / L LiPF6 as the lithium salt, a mixed solvent of EC, DEC, and EMC (mass ratio 1:1:1), and 1% VC (ethylene carbonate) as the additive. The separator was Celgard 2500. The battery underwent charge-discharge cycling using a Blue Electric device. The charge-discharge program was: 2 hours of rest, 0.5 mAh / cm³... 2 Charge for 1 hour, discharge for 1 hour, and cycle for 5 times. Afterward, disassemble the lithium battery and spray a 1 mg / mL solution of phenylboronic fluorescein ether onto the surface of the lithium metal anode. After the ether evaporates, irradiate the surface under a 365 nm handheld UV lamp. The fluorescence pattern is shown below. Figure 7 As shown in (a).

[0125] Example 3

[0126] The assembly method and fluorescence characterization techniques for the lithium metal battery were basically the same as in Example 2, except that the additive was replaced by 1% VC (ethylene carbonate) by 1% FEC (fluoroethylene carbonate) to increase the LiF content at the interface of the comparative example's negative electrode. The fluorescence image is shown below. Figure 7 As shown in (b), the fluorescence signal data are detailed in Table 1.

[0127] Example 4

[0128] The assembly method and fluorescence characterization techniques for lithium metal batteries are basically the same as those in Example 3. The difference is that the fluorescent probe reagent is replaced by an ether solution of 1 mg / mL phenylboronic fluoranthene ester in ether with a concentration of 1 mg / mL pyridineboronic fluoranthene ester in ether. The fluorescence signal data are detailed in Table 1.

[0129] The structural formula of pyridine borate fluoranthene is as follows: The preparation process is the same as that of phenylboronic acid fluoranthene in Example 1, except that phenylboronic acid is replaced with pyridineboronic acid, and the other steps are the same as in Example 1.

[0130] Example 5

[0131] The assembly method and fluorescence characterization techniques of the lithium metal battery are basically the same as those in Example 3. The difference is that the fluorescent probe reagent is replaced by an ether solution of 1 mg / mL phenylboronic fluoranthene ester in ether with a concentration of 1 mg / mL dihydroxyfluoranthene (i.e., the raw material in the synthesis process of Example 1) in ether. The fluorescence signal data are detailed in Table 1.

[0132] The structural formula of dihydroxyfluoranthracene is:

[0133] from Figure 7As can be seen, the negative electrode interface of Example 2 exhibits overall yellow fluorescence after interacting with the probe molecules; the electrode interface of Example 3 shows a significant increase in orange fluorescence signal and a wider distribution area after interacting with the probe molecules, indicating that the lithium fluoride abundance at the electrode interface of Example 3 is higher, and the fluorescence observation results are consistent with the differences between groups. Furthermore, high-resolution observation can be performed using a fluorescence microscope to visualize the specific distribution differences and morphology of lithium fluoride; and quantitative analysis of the relative abundance of lithium fluoride at the interface can be performed by measuring the fluorescence intensity using a fluorescence spectrometer.

[0134] As shown in Table 1, the fluorescence signal data indicates that after adjusting the R9 group of the pyridine borosilicate fluoranthene used in Example 4, the intrinsic fluorescence emission was 551 nm, and the fluorescence emission after interaction with lithium fluoride became 574 nm, still showing a response shift of 23 nm. The results of Example 4 demonstrate that, without altering the borosilicate structure, modifying the remaining R groups with different substituents not only does not affect the imaging characterization effect on lithium fluoride, but also allows for the artificial control of the fluorescence emission position.

[0135] The dihydroxyfluoranthracene used in Example 5 does not contain a boron ester structure, and its fluorescence emission before and after interaction with lithium fluoride is located at 513 nm, showing no specific response to lithium fluoride. The results of Example 5 demonstrate that the boron ester structure is a necessary part for this type of fluorescent probe to achieve lithium fluoride imaging characterization, and the response mechanism is based on the coordination of boron and fluorine.

[0136] Table 1

[0137] Intrinsic fluorescence emission (nm) 549 551 513 Fluorescence emission (nm) after interaction with F- 575 574 513 Fluorescence response shift (nm) 26 23 0

[0138] It should be noted that the above explanation uses the Li|Li symmetric coin cell as an example only, but it is not limited to this. It can also be used in lithium-sulfur batteries, lithium-air batteries, lithium-oxygen batteries, lithium-oxide batteries, and other batteries containing lithium metal anodes. Boron ester fluoranthene compounds are not limited to phenylboron ester fluoranthene and pyridineboron ester fluoranthene, but also include a series of boron ester fluoranthene compounds containing other substituents.

[0139] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0140] The above-described embodiments are merely illustrative of several implementation methods of the present invention, facilitating a detailed understanding of the technical solutions of the present invention, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided by the present invention through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this invention patent should be determined by the content of the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A boron ester fluoranthene compound, characterized in that, It has the following general structural formula: ； Among them, R1 to R8 are independently selected from hydrogen, C1 to C2, respectively. 10 Alkyl groups and C3~C 10 One or more of the cycloalkyl groups; R9 is selected from C5~C6. 10 Aryl and C3~C 10 One type of heteroaryl group, wherein at least one carbon atom is replaced by a non-carbon atom in the aryl group, and the non-carbon atom is an N atom.

2. The boron ester fluoranthene compound according to claim 1, characterized in that, The structural formula of the boron ester fluoranthene compound is as follows: or .

3. A method for preparing the boron ester fluoranthene compound according to claim 1, characterized in that, Includes the following steps: Compound 1 was reacted with boron tribromide to prepare compound 2. The structural formula of compound 1 is as follows: The structural formula of compound 2 is as follows: R1~R8 are R1~R8 in the boron ester fluoranthene compound according to claim 1; The compound 2 was reacted with R9-B(OH)2 to prepare a boron ester fluoranthene compound, wherein R9 is the R9 in the boron ester fluoranthene compound of claim 1.

4. The method for preparing the boron ester fluoranthene compound according to claim 3, characterized in that, The preparation method satisfies at least one of the following conditions: (1) The steps of reacting compound 1 with boron tribromide include: adding an anhydrous dichloromethane solution containing boron tribromide to an anhydrous dichloromethane solution containing compound 1 at -78℃ to -20℃, and after the addition is completed, raising the temperature to 10℃ to 30℃ and reacting for 24h to 48h. (2) The step of reacting the compound 2 with R9-B(OH)2 includes: mixing the compound 2 with the R9-B(OH)2 in anhydrous tetrahydrofuran and shaking at 10°C to 30°C for 10 min to 60 min.

5. The application of a boron ester fluoranthene compound in the detection of lithium fluoride in solid electrolyte interfacial membranes, characterized in that, The boron ester fluoranthene compound is the boron ester fluoranthene compound according to any one of claims 1 to 2 or the boron ester fluoranthene compound prepared by the preparation method according to any one of claims 3 to 4.

6. The application according to claim 5, characterized in that, Includes the following steps: A lithium battery is provided, wherein a solid electrolyte interface film is formed on the surface of the lithium metal negative electrode; A solution containing the boron ester fluoranthene compound is attached to the surface of the lithium metal anode where a solid electrolyte interface film is formed. The lithium metal anode is irradiated with an excitation light source to obtain fluorescence information on the surface of the lithium metal anode. Lithium fluoride in the solid electrolyte interface membrane is detected based on the fluorescence information.

7. The application according to claim 6, characterized in that, The step of irradiating the lithium metal anode with an excitation light source to obtain fluorescence information on the surface of the lithium metal anode satisfies at least one of the following conditions: (1) Observe the fluorescence on the surface of the lithium metal anode directly under a handheld ultraviolet light; (2) The surface of the lithium metal anode was observed or photographed under a fluorescence microscope with high resolution; (3) The surface of the lithium metal anode was analyzed in a fluorescence spectrometer.

8. The application according to claim 6 or 7, characterized in that, The step of detecting lithium fluoride in the solid electrolyte interface membrane based on the fluorescence information satisfies at least one of the following conditions: (1) Determine whether the solid electrolyte interface film contains lithium fluoride based on the fluorescence color; (2) Determine the distribution of lithium fluoride in the solid electrolyte interface film based on the fluorescence signal distribution; (3) The content of lithium fluoride in the solid electrolyte interface membrane was quantitatively analyzed based on the fluorescence intensity.

9. The application according to claim 6, characterized in that, The solution containing the boron ester fluoranthene compound satisfies at least one of the following conditions: (1) The concentration of the solution containing the boron ester fluoranthene compound is 0.5 mg / mL to 5 mg / mL; (2) The solvent used in the solution containing the boron ester fluoranthene compound is any one or more of diethyl ether, tetrahydrofuran, acetone, n-hexane and cyclohexane.

10. The application according to any one of claims 6-7 and 9, characterized in that, The lithium battery is any one or more of the following: lithium-lithium symmetric battery, lithium-sulfur battery, lithium-oxygen battery, lithium-air battery, and lithium-oxide battery.

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