Method for detecting surface composition of lithium metal negative electrode

Abstract

The application relates to the field of fluorescence detection technology, in particular to a detection method for the surface composition of a lithium metal negative electrode. The lithium metal negative electrode is a lithium metal negative electrode after charge-discharge cycle in a lithium battery. The detection method for the surface composition of the lithium metal negative electrode comprises the following steps: using a quinazolinone derivative as a fluorescent probe to detect the surface composition of the lithium metal negative electrode; the structural formula of the quinazolinone derivative is as follows: R1 is a substituted or unsubstituted aryl group or a heteroaryl group; R2-R5 are independently selected from one or more of the following: -H, a substituted or unsubstituted aryl group, a heteroaryl group, an arylamine group, an imide group, a cycloalkyl group, a heterocyclic group, a halogen, an amino group, a nitro group, a cyano group, an isocyano group, an acyl group, an alkyl group, an alkylene group, a heteroalkyl group, an alkenyl group, an alkenylene group, an alkynyl group, an alkynylene group, an ester group and an alkoxy group. The detection method provided by the application can realize visual and quantitative detection of the surface composition of the lithium metal negative electrode.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fluorescence detection technology, in particular to a detection method of lithium metal negative electrode surface composition. BACKGROUND

[0002] Metal negative electrode has extremely low potential and extremely high energy density, and is a breakthrough for constructing a new generation of secondary batteries, which has attracted extensive attention from industry, academia and research in recent years. However, the lithium negative electrode always faces problems such as uneven lithium deposition (lithium dendrite), active material loss of electrode and electrolyte caused by side reactions, and decrease of coulombic efficiency during long-term cycling. On the one hand, the solid electrolyte interface film (SEI) formed by chemical and electrochemical reactions between the highly active lithium metal negative electrode and the electrolyte and additives is considered to be a key factor determining the long cycle performance of the battery, especially the micro-morphology, interface distribution, chemical and thermodynamic properties of the SEI play a direct and key role in the negative electrode behavior. On the other hand, lithium dendrite is a dendritic metal crystal similar to a tree produced by irregular electrodeposition of highly active lithium atoms on nucleation sites, which not only leads to deterioration of battery performance, decrease of coulombic efficiency and accelerated capacity decay, but also easily causes internal short circuit of the battery and triggers thermal runaway, which has serious safety hazards.

[0003] Due to the complexity of the battery system and the unique characteristics of lithium metal, the nucleation and growth behavior of lithium dendrite is also affected by many factors, and the current detection means is difficult to characterize and directly observe in depth. SUMMARY

[0004] Therefore, it is necessary to provide a detection method of lithium metal negative electrode surface composition, which can realize visual observation and quantitative detection of deposited lithium, lithium dendrite, by-products, dead lithium and solid electrolyte interface film on the surface of the lithium metal negative electrode.

[0005] In a first aspect, the present application provides a detection method of lithium metal negative electrode surface composition, the lithium metal negative electrode being a lithium metal negative electrode after charge-discharge cycling in a lithium battery, and the method comprising the following steps:

[0006] A quinazolinone derivative is used as a fluorescent probe to detect the composition on the surface of the lithium metal negative electrode; the structural formula of the quinazolinone derivative is shown as formula I:

[0007]

[0008] wherein R1 is a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group;

[0009] R2-R5are each independently selected from one or more of -H, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted arylamine, amido, substituted or unsubstituted cycloalkyl, substituted or unsubstituted heterocyclyl, halogen, amino, nitro, cyano, isocyano, acyl, alkyl, alkylene, heteroalkyl, alkenyl, alkenylene, alkynyl, alkynylene, ester, and alkoxy.

[0010] In some embodiments, R1is substituted or unsubstituted C6-Ci2aryl, or substituted or unsubstituted C4-Ci2heteroaryl. 16 In some embodiments, R1is substituted or unsubstituted C6-Ci2aryl, or substituted or unsubstituted C4-Ci2heteroaryl. 13 In some embodiments, R1is substituted or unsubstituted C6-Ci2aryl, or substituted or unsubstituted C4-Ci2heteroaryl.

[0011] R2-R5are each independently selected from one or more of -H, substituted or unsubstituted C6-Ci2aryl, substituted or unsubstituted C4-Ci2heteroaryl, substituted or unsubstituted arylamine, amido, halogen, amino, nitro, cyano, isocyano, acyl, alkyl, and alkoxy. 18 R2-R5are each independently selected from one or more of -H, substituted or unsubstituted C6-Ci2aryl, substituted or unsubstituted C4-Ci2heteroaryl, substituted or unsubstituted arylamine, amido, halogen, amino, nitro, cyano, isocyano, acyl, alkyl, and alkoxy.

[0012] In some embodiments, R1is substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthryl, substituted or unsubstituted phenanthryl, substituted or unsubstituted pyrenyl, substituted or unsubstituted pyridyl, substituted or unsubstituted pyrimidyl, substituted or unsubstituted pyrazinyl, substituted or unsubstituted s-triazinyl, substituted or unsubstituted furanyl, substituted or unsubstituted thienyl, substituted or unsubstituted pyrrolyl, substituted or unsubstituted pyrazolyl, substituted or unsubstituted imidazolyl, substituted or unsubstituted oxazolyl, or substituted or unsubstituted thiazolyl.

[0013] R2-R5are each independently selected from one or more of -H, nitro, formyl, triphenylamine, methoxy, and maleimide.

[0014] In some embodiments, R1is substituted or unsubstituted phenyl.

[0015] R2-R5are each independently selected from one or more of -H, nitro, formyl, triphenylamine, methoxy, and maleimide.

[0016] In some embodiments, the quinazolinone derivative comprises one or more of phenylquinazolinone, 3-methoxyphenylquinazolinone, 4-nitrophenylquinazolinone, 4-formylphenylquinazolinone, triphenylaminophenylquinazolinone, 4-pyridylquinazolinone, and 2-furanylquinazolinone.

[0017] In some embodiments, the step of detecting comprises:

[0018] preparing a probe solution comprising the quinazolinone derivative;

[0019] contacting the probe solution with a surface of the lithium metal negative electrode, and performing a fluorescence test on the surface of the lithium metal negative electrode to detect a composition of the surface of the lithium metal negative electrode.

[0020] In some embodiments, the step of performing the fluorescence test comprises:

[0021] irradiating the surface of the lithium metal negative electrode with excitation light, and qualitatively analyzing a composition of the surface of the lithium metal negative electrode according to a fluorescence signal distribution of the surface of the lithium metal negative electrode;

[0022] and / or irradiating the surface of the lithium metal negative electrode with excitation light, and quantitatively analyzing a composition of the surface of the lithium metal negative electrode according to a difference in fluorescence intensity of different distribution regions of the surface of the lithium metal negative electrode.

[0023] In some embodiments, the detection method has at least one of the following features:

[0024] 1) the solvent adopted by the probe solution comprises one or more of an ether solvent, an alkane solvent, a furan solvent, a ketone solvent, and a nitrile solvent;

[0025] 2) the excitation light is ultraviolet light with a wavelength of 300 nm to 365 nm.

[0026] In some embodiments, the concentration of the quinazolinone derivative in the probe solution is 0.5 mg / mL to 5 mg / mL.

[0027] In some embodiments, the detection item of the detection comprises one or more of deposited lithium, a byproduct, lithium dendrites, dead lithium, and a solid electrolyte interface film on the surface of the lithium metal negative electrode.

[0028] The byproduct comprises a lithium salt and / or a polymer, the lithium salt comprises one or more of lithium fluoride, lithium chloride, lithium acetate, lithium carbonate, lithium hydroxide, lithium oxide, and lithium alcoholate, and the polymer comprises one or more of polyvinyl carbonate, polycarbonate, and polypropylene.

[0029] The detection method provided in the application takes quinazolinone derivatives as probes, the quinazolinone derivative skeleton structure contains a high-activity lactam group, the lactam group can react with active lithium, lithium dendrites and inhomogeneous lithium deposition on the surface of the lithium metal negative electrode, resulting in changes in fluorescence color and signal before and after the reaction; the lactam group does not react with by-products and SEI films on the surface of the lithium metal negative electrode, and the fluorescence color and signal do not change, i.e. the intrinsic fluorescence emission is maintained. Therefore, the use of quinazolinone derivatives as probes forms more intuitive and accurate fluorescence change differences, so that visual detection can be realized according to the fluorescence color change and signal distribution before and after the reaction, to qualitatively detect the composition and distribution on the surface of the lithium metal negative electrode.

[0030] Meanwhile, the aryl or heteroaryl group of the quinazolinone derivative makes it difficult to move in a solid-state system, the molecular rotation is limited, the conjugated plane structure in the quinazolinone derivative molecule can be extended, so that the quinazolinone derivative has a high fluorescence emission yield, and thus has a significant fluorescence intensity after reacting with the lithium metal negative electrode. Through fluorescence intensity detection, the micro-morphology of the lithium metal negative electrode surface and the accumulation degree and relative abundance of various components can be recognized, so that quantitative detection of the components on the surface of the lithium metal negative electrode is realized. Moreover, the fluorescence detection imaging result is basically consistent with the real appearance of the surface of the lithium metal negative electrode, and the performance degradation and failure of the battery and the existing safety hazards and other problems are linked to the accumulation amount of lithium dendrites, inhomogeneous lithium deposition and by-products on the surface of the lithium metal negative electrode, so as to provide feasibility for analyzing the causes of battery failure and early prevention and early warning of battery performance failure.

[0031] In addition, the detection method provided in the application is simple, convenient, high in sensitivity and accuracy, and can realize direct observation and quantitative detection of the components on the surface of the lithium metal negative electrode at the same time, and can provide intuitive, visual and quantitative characterization results for analyzing the surface of the lithium metal negative electrode. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a process flow chart of the lithium metal negative electrode surface component detection method in an embodiment;

[0033] Figure 2 It is a fluorescence map of the surface of the lithium metal negative electrode before and after spraying the phenyl quinazolinone probe solution in Example 1;

[0034] Figure 3 It is a fluorescence spectrum map of the phenyl quinazolinone before and after the lithium metal reaction;

[0035] Figure 4 It is a fluorescence stability spectrum map of the phenyl quinazolinone before and after the lithium metal reaction;

[0036] Figure 5The fluorescence spectra of 3-methoxyphenylquinazolinone before and after the reaction with lithium metal are shown.

[0037] Figure 6 The fluorescence spectra of quinazolinone before and after its reaction with lithium metal are shown. Detailed Implementation

[0038] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application 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 this application.

[0039] 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 application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0040] the term:

[0041] As used herein, the term "and / or" encompasses any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" includes three parallel options: A, B, and "a combination of A and B".

[0042] In this document, terms such as "further," "even further," "especially," "for example," "as," "example," and "exemplary" are used for descriptive purposes to indicate a connection in the coverage of different technical solutions presented earlier and later. However, they should not be construed as limitations on the preceding technical solution or on the scope of protection of this document. Unless otherwise specified, A (as in B) indicates that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0043] In this document, the terms "first aspect," "second aspect," "third aspect," and "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," and "fourth" serve only as a non-exhaustive enumeration and should be understood as not constituting a closed limitation on quantity.

[0044] In this application, "substitution" means that the hydrogen atom in the substituent is replaced by the substituent.

[0045] In the present application, "alkyl" can mean straight chain and / or branched alkyl groups. The number of carbons in the alkyl group can be 1 to 50, 1 to 30, 1 to 20, 1 to 10, or 1 to 6. Phrases containing this term, for example, "C1-C6 alkyl" means that the alkyl group can be a C1 alkyl, a C2 alkyl, a C3 alkyl, a C4 alkyl, a C5 alkyl, a C6 alkyl, a C7 alkyl, a C8 alkyl, or a C9 alkyl, each occurrence independently. 1-9 "Alkyl" means an alkyl group containing 1 to 9 carbon atoms, which can be, independently for each occurrence, a C1 alkyl, a C2 alkyl, a C3 alkyl, a C4 alkyl, a C5 alkyl, a C6 alkyl, a C7 alkyl, a C8 alkyl, or a C9 alkyl. Non-limiting examples of alkyl groups include methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, t-butyl, i-butyl, 2-ethylbutyl, 3,3-dimethylbutyl, n-pentyl, i-pentyl, neopentyl, t-pentyl, cyclopentyl, 1-methylpentyl, 3-methylpentyl, 2-ethylpentyl, 4-methyl-2-pentyl, n-hexyl, 1-methylhexyl, 2-ethylhexyl, 2-butylhexyl, cyclohexyl, n-triacontyl, adamantyl, and the like.

[0046] "Aryl or aromatic group" means an aromatic hydrocarbon group derived by the removal of one hydrogen atom from a single ring aromatic compound, or from a fused ring aromatic compound, or from a polycyclic aromatic ring system, at least one of which is an aromatic ring system. For example, "substituted or unsubstituted C6-C 16 "Aryl or aromatic group" means an aromatic hydrocarbon group derived by the removal of one hydrogen atom from a single ring aromatic compound, or from a fused ring aromatic compound, or from a polycyclic aromatic ring system, at least one of which is an aromatic ring system. For example, "substituted or unsubstituted C6-C

[0047] "Heteroaryl or heteroaromatic group" means an aromatic group in which at least one carbon atom of the aryl group is replaced by a non-carbon atom, which can be a N atom, an O atom, an S atom, and the like. For example, "substituted or unsubstituted C4-C 13 "Heteroaryl or heteroaromatic group" means an aromatic group in which at least one carbon atom of the aryl group is replaced by a non-carbon atom, which can be a N atom, an O atom, an S atom, and the like. For example, "substituted or unsubstituted C4-C

[0048] The term "alkenyl" means a monoradical of a branched or unbranched unsaturated hydrocarbon group having 2 to 40 carbon atoms, 2 to 10 carbon atoms, or 2 to 6 carbon atoms and having at least one site of ethylenic unsaturation (e.g., 1 to 6 sites).

[0049] The term "alkynyl" means a monoradical of an unsaturated hydrocarbon having 2 to 40 carbon atoms, 2 to 20 carbon atoms, or 2 to 6 carbon atoms and having at least one site of acetylenic (triple bond) unsaturation (e.g., 1 to 6 sites).

[0050] The term "alkoxy" refers to alkyl-O-, alkenyl-O-, and alkynyl-O- groups, wherein alkyl, alkenyl, and alkynyl are as defined herein.

[0051] The term "halo" or "halogen" refers to fluoro, chloro, bromo, and iodo.

[0052] The uneven lithium deposition, lithium dendrite and solid-state electrolyte interface film (SEI) formed on the surface of the lithium battery negative electrode have a significant impact on the performance of the battery, such as reducing the coulombic efficiency and accelerating the capacity decay, and easily causing the battery thermal runaway, which has serious safety hazards. Therefore, detecting the composition on the surface of the lithium metal negative electrode plays an important role in monitoring the performance of the battery, and the current detection method cannot directly observe and cannot quantitatively characterize the composition on the surface of the lithium metal negative electrode. Therefore, the present application provides a detection method of the composition of the lithium metal negative electrode to realize visual observation and quantitative detection of the composition on the surface of the lithium metal negative electrode.

[0053] In a first aspect, the present application provides a detection method of the composition of a lithium metal negative electrode, the lithium metal negative electrode being a lithium metal negative electrode after charge-discharge cycle in a lithium battery, and the method comprising the following steps:

[0054] A quinazolinone derivative is used as a fluorescent probe to detect the composition on the surface of the lithium metal negative electrode; the structural formula of the quinazolinone derivative is shown as formula I:

[0055]

[0056] R1 is a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group;

[0057] R2-R5 are independently selected from one or more of -H, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, a substituted or unsubstituted arylamine group, an imide group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted heterocyclic group, a halogen, an amino group, a nitro group, a cyano group, an isocyano group, an acyl group, an alkyl group, an alkylene group, a heteroalkyl group, an alkenyl group, an alkenylene group, an alkynyl group, an alkynylene group, an ester group, and an alkoxy group.

[0058] The detection method provided in this application uses a quinazolinone derivative as a probe. The quinazolinone derivative's backbone structure contains highly reactive lactam groups. These lactam groups can react with active lithium, lithium dendrites, and uneven lithium deposition on the lithium metal anode surface, causing changes in fluorescence color and signal before and after the reaction. However, the lactam groups do not react with byproducts and the SEI film on the lithium metal anode surface, and the fluorescence color and signal remain unchanged, i.e., intrinsic fluorescence emission is maintained. Therefore, using a quinazolinone derivative as a probe creates a more intuitive and precise difference in fluorescence changes, enabling visual detection based on the changes in fluorescence color and signal distribution before and after the reaction, thus allowing for qualitative detection of the composition and distribution on the lithium metal anode surface.

[0059] Meanwhile, the aryl or heteroaryl groups of quinazolinone derivatives make molecular movement difficult in the solid state, restricting molecular rotation and extending the conjugated planar structure within the quinazolinone derivative molecule, resulting in high fluorescence emission yield and significant fluorescence intensity after reaction with the lithium metal anode. Fluorescence intensity detection can identify the microstructure of the lithium metal anode surface and the accumulation degree and relative abundance of various components, thus achieving quantitative detection of components on the lithium metal anode surface. Furthermore, the fluorescence imaging results largely correspond to the actual appearance of the lithium metal anode surface. Based on the fluorescence imaging results, battery performance degradation, failure, and potential safety hazards can be linked to lithium dendrites, uneven lithium deposition, and the accumulation of byproducts on the lithium metal anode surface, potentially providing feasibility for analyzing the causes of battery failure and early prevention and warning of battery performance failure.

[0060] Furthermore, the detection method provided in this application is simple and convenient, with high sensitivity and accuracy. It can simultaneously achieve direct observation and quantitative detection of the composition of lithium metal anode surface, providing intuitive, visual and quantitative characterization results for the analysis of lithium metal anode surface.

[0061] It should be noted that the mechanism by which aryl or heteroaryl groups make it difficult for quinazolinone derivatives to undergo molecular motion in the solid state is specifically the "restriction of intramolecular motions" (RIM) mechanism.

[0062] In this application, "substituted or unsubstituted" means that the defined group may or may not be substituted. When the defined group is substituted, it should be understood that it may be substituted by a group acceptable in the art, including but not limited to: cyano, isocyano, nitro, halogen, C1- 10 Alkyl, C1~ 10 alkoxy, acyl, C6~ 30 Aryl, C3~ 30substituted or unsubstituted C6-C10aryl, or substituted or unsubstituted C4-C10heteroaryl; 30 substituted or unsubstituted C6-C10aryl, or substituted or unsubstituted C4-C10heteroaryl;

[0063] In some embodiments, R1is substituted or unsubstituted C6-C10aryl, or substituted or unsubstituted C4-C10heteroaryl. 16 substituted or unsubstituted C6-C10aryl, or substituted or unsubstituted C4-C10heteroaryl; 13 substituted or unsubstituted C6-C10aryl, or substituted or unsubstituted C4-C10heteroaryl;

[0064] R2-R5are each independently selected from one or more of -H, substituted or unsubstituted C6-C10aryl, or substituted or unsubstituted C4-C10heteroaryl. 18 substituted or unsubstituted C6-C10aryl, or substituted or unsubstituted C4-C10heteroaryl.

[0065] Further, R1is substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthryl, substituted or unsubstituted phenanthryl, substituted or unsubstituted pyrenyl, substituted or unsubstituted pyridyl, substituted or unsubstituted pyrimidyl, substituted or unsubstituted pyrazinyl, substituted or unsubstituted s-triazinyl, substituted or unsubstituted furanyl, substituted or unsubstituted thienyl, substituted or unsubstituted pyrrolyl, substituted or unsubstituted pyrazolyl, substituted or unsubstituted imidazolyl, substituted or unsubstituted oxazolyl, or substituted or unsubstituted thiazolyl.

[0066] R2-R5are each independently selected from one or more of -H, nitro, formyl, triphenylamine, methoxy, and maleimide.

[0067] Further, R1is substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthryl, substituted or unsubstituted phenanthryl, substituted or unsubstituted pyrenyl, substituted or unsubstituted pyridyl, substituted or unsubstituted pyrimidyl, substituted or unsubstituted pyrazinyl, substituted or unsubstituted s-triazinyl, substituted or unsubstituted furanyl, substituted or unsubstituted thienyl, substituted or unsubstituted pyrrolyl, substituted or unsubstituted pyrazolyl, substituted or unsubstituted imidazolyl, substituted or unsubstituted oxazolyl, or substituted or unsubstituted thiazolyl.

[0068] R2-R5are each independently selected from one or more of -H, nitro, formyl, triphenylamine, methoxy, and maleimide.

[0069] Specifically, the quinazolinone derivative can include one or more of phenylquinazolinone (CAS No. 1022-45-3), 3-methoxyphenylquinazolinone (CAS No. 56071-04-6), 4-nitrophenylquinazolinone (CAS No. 4765-59-7), 4-formylphenylquinazolinone (CAS No. 1801530-64-2), triphenylaminophenylquinazolinone (CAS No. 1396108-98-7), 4-pyridylquinazolinone (CAS No. 6484-23-7), and 2-furanylquinazolinone (CAS No. 26059-84-7). Among them, the structural formulas of phenylquinazolinone, 3-methoxyphenylquinazolinone, 4-nitrophenylquinazolinone, 4-formylphenylquinazolinone, triphenylaminophenylquinazolinone, 4-pyridylquinazolinone, and 2-furanylquinazolinone are respectively shown in Formulas 1-7:

[0070]

[0071]

[0072] Please refer to Figure 1 In some embodiments, the method for detecting the composition of the lithium metal negative electrode specifically comprises steps S100-S300:

[0073] S100: After the charge-discharge test of the lithium battery, the lithium metal negative electrode is taken out. In some embodiments, step S100 can be omitted.

[0074] S200: Prepare a probe solution containing a quinazolinone derivative.

[0075] In some embodiments, the step of preparing the probe solution comprises:

[0076] The quinazolinone derivative is dissolved in a solvent to form a probe solution. The selection of the solvent is not limited, and an inert solvent with volatility can be selected. In some embodiments, the solvent includes one or more of ether solvents, furan solvents, alkane solvents, furan solvents, ketone solvents, and nitrile solvents. Specifically, the ether solvent can be diethyl ether; the furan solvent can be tetrahydrofuran; the alkane solvent can be n-hexane and / or cyclohexane; the ketone solvent can be acetone; and the nitrile solvent can be acetonitrile.

[0077] In some embodiments, the concentration of the quinazolinone derivative in the probe solution is 0.5 mg / mL to 5 mg / mL, for example, 0.5 mg / mL, 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, and preferably 1 mg / mL. The best detection effect can be obtained when the concentration of the quinazolinone derivative is 1 mg / mL.

[0078] Step S300: Contact the probe solution with the surface of the lithium metal negative electrode, and perform fluorescence testing on the surface of the lithium metal negative electrode to detect the composition on the surface of the lithium metal negative electrode.

[0079] In some embodiments, the step of performing fluorescence testing on the surface of the lithium metal negative electrode comprises:

[0080] Irradiate the surface of the lithium metal negative electrode with excitation light, and qualitatively analyze the composition on the surface of the lithium metal negative electrode according to the fluorescence signal distribution on the surface of the lithium metal negative electrode;

[0081] And / or, irradiate the surface of the lithium metal negative electrode with excitation light, and quantitatively analyze the composition on the surface of the lithium metal negative electrode according to the fluorescence intensity difference of different distribution regions on the surface of the lithium metal negative electrode.

[0082] Specifically, by observing the fluorescence signal distribution on the surface of the lithium metal negative electrode, different components on the surface of the lithium metal negative electrode can be distinguished, and visual analysis of the surface of the lithium metal negative electrode can be realized. The fluorescence intensity and wavelength of the surface of the lithium metal negative electrode measured by the fluorescence spectrometer can realize the semi-quantitative analysis of the above detection items.

[0083] In some embodiments, contacting the probe solution with the surface of the lithium metal negative electrode specifically refers to spraying the probe solution to the surface of the lithium metal negative electrode.

[0084] In the present application, the excitation light specifically refers to light waves capable of exciting the quinazolinone derivative to emit fluorescence. In some embodiments, the excitation light is ultraviolet light with a wavelength of 300-365 nm. Preferably, the excitation light is ultraviolet light with a wavelength of 320 nm.

[0085] It can be understood that the by-product is the product of the side reaction occurring on the surface of the lithium metal negative electrode. When the battery is subjected to charge and discharge cycles with different cycle numbers and different charge and discharge currents, the method provided by the present application can visually and semi-quantitatively analyze the battery under different conditions.

[0086] In some embodiments, the detection items of the detection include one or more of the deposited lithium, by-products, lithium dendrites, dead lithium and solid electrolyte interface film (SEI) on the surface of the lithium metal negative electrode. Among them, the lactam group in the quinazolinone derivative can react with active lithium, unevenly deposited lithium and lithium dendrites, resulting in changes in fluorescence color and signal before and after the reaction (white solid fluorescence before the reaction, blue solid fluorescence after the reaction); and the lactam group will not react with the by-products and SEI film on the surface of the lithium metal negative electrode, and the fluorescence color and signal will not change, i.e. the intrinsic fluorescence emission is maintained. Therefore, according to the differences in fluorescence color and signal, different components on the surface of the lithium metal negative electrode can be distinguished to realize the visual analysis of the surface of the lithium metal negative electrode. According to the differences in fluorescence intensity, the abundance of unevenly deposited lithium or lithium dendrites, the distribution of lithium dendrites, the accumulation degree of by-products, the growth degree and distribution area of SEI film in different regions can be directly reflected, and quantitative analysis of different components can be realized through the fluorescence spectrometer. Specifically, the by-products include lithium salts and / or polymers, the lithium salts include one or more of lithium fluoride, lithium chloride, lithium acetate, lithium carbonate, lithium hydroxide, lithium oxide and lithium alcoholate, and the polymers include one or more of polyvinylidene carbonate, polycarbonate and polypropylene.

[0087] In some embodiments, the lithium battery is a lithium-oxygen battery, a lithium-sulfur battery, a lithium-oxide battery, a lithium-air battery or a lithium-lithium battery.

[0088] The application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate but not to limit the scope of the application. The experimental methods in the following examples, if not otherwise specified, are preferred to refer to the instructions given in the application, but also can be in accordance with the experimental manual or conventional conditions in the art, or in accordance with the conditions suggested by the manufacturer, or in accordance with the experimental methods known in the art.

[0089] The lithium metal battery used in the following examples is Li|Li symmetric coin cell, both the positive and negative electrodes are lithium sheet, the electrolyte is 1 mol / L LiPF6 / (EC+DEC+EMC) (the mass ratio of EC, DEC and EMC is 1:1:1), and the separator is Celgard 2500.

[0090] Example 1

[0091] (1) The symmetric coin cell was subjected to charge-discharge cycle by using the blue light equipment, and the charge-discharge program was 2h of static state, 1.0mAh / cm 2 2h of discharge, 10 cycles, to simulate the situation of the battery after use. Then the battery was disassembled, and the negative lithium sheet was taken out, and the macroscopic morphology of the negative lithium sheet is shown in Figure 2 (a);

[0092] (2) The phenylquinazolinone was dissolved in diethyl ether to prepare a solution with a concentration of 1mg / mL, to obtain a phenylquinazolinone probe solution;

[0093] (3) The phenylquinazolinone probe solution prepared in step (2) was sprayed on the surface of the negative lithium sheet in step (1), and after the diethyl ether was volatilized, the fluorescence image was obtained under the irradiation of the ultraviolet light with a wavelength of 320nm, as shown in Figure 2 (b). Among them, the blue fluorescence is active lithium (lithium sheet substrate), non-uniform lithium deposition and lithium dendrite; the white fluorescence is the by-product and SEI film. As can be seen from Figure 2 (a) and (b), the fluorescence distribution after the reaction of phenylquinazolinone with the surface of lithium metal negative electrode is basically consistent with the morphology of the surface of lithium metal negative electrode, and the imaging contrast is very high, with high readability and visibility. The blue and white fluorescence intensity can intuitively reflect the abundance of lithium non-uniform deposition or lithium dendrite, the degree of by-product accumulation, etc.

[0094] The molecular structure changes of phenylquinazolinone before and after the reaction with lithium metal are shown as follows:

[0095]

[0096] After reacting with elemental lithium metal, phenylquinazolinone transforms into a stable phenolic salt structure via an enol tautomerization anionic intermediate. Before the reaction, phenylquinazolinone exhibits white solid-state fluorescence; upon reaction with lithium metal, it forms phenylquinazolinone lithium salt, and its fluorescence emission turns blue, indicating its responsiveness to lithium metal. This makes it suitable for imaging characterization of interfacial species at the lithium metal anode in lithium-ion batteries.

[0097] Figure 3 The images show the fluorescence spectra of phenylquinazolinone before and after the reaction with lithium metal. Figure 3 (a) It can be seen that before reacting with lithium metal, phenylquinazolinone exhibits a double fluorescence peak under 320 nm excitation light, located at 399 nm and 538 nm respectively, showing white fluorescence; Figure 3 (b) It is evident that after phenylquinazolinone reacts with lithium metal, it exhibits a single fluorescence peak at 396 nm, while the original fluorescence peak at 538 nm disappears, resulting in blue fluorescence. The fluorescence signal before and after the reaction shows a significant difference, high contrast, and high emission intensity, indicating good readability and visibility. Therefore, different chemical components (lithium or byproducts) can be identified based on the fluorescence color change on the lithium anode surface; the approximate distribution area of ​​various species on the electrode surface can be determined based on the fluorescence signal distribution; and the accumulation degree of various species can be observed based on the difference in fluorescence intensity, and quantitative analysis can be achieved through fluorescence spectroscopy.

[0098] Figure 4 This is a fluorescence stability spectrum of phenylquinazolinone before and after its reaction with lithium metal. Figure 4 (a) It can be seen that after continuous excitation with 320 nm wavelength for 1 h, the fluorescence intensity of phenylquinazolinone at 399 nm remains at 90.2%; Figure 4 (b) It can be seen that after continuous excitation for 1 hour under 320 nm wavelength excitation light, the fluorescence intensity of phenylquinazolinone lithium salt after reaction with lithium metal remains at 47.5% at 396 nm, indicating that phenylquinazolinone has good fluorescence stability and anti-photobleaching ability before and after reaction with lithium metal.

[0099] Example 2

[0100] The preparation method of Example 2 is basically the same as that of Example 1, except that 3-methoxyphenylquinazolinone (CAS No. 56071-04-6) is used instead of phenylquinazolinone in Example 1 to prepare a 3-methoxyphenylquinazolinone probe solution of the same concentration. The fluorescence spectra of 3-methoxyphenylquinazolinone before and after interaction with lithium metal are shown below. Figure 5 As shown. By Figure 5 (a) It can be seen that 3-methoxyphenylquinazolinone exhibits a double emission peak before reacting with lithium metal, located at 397 nm and 521 nm, respectively, and displays white fluorescence;Figure 5 (b)As can be seen, 3-methoxyphenylquinazolinone shows a single emission peak at 413 nm after interacting with lithium metal, presenting blue fluorescence. The imaging characterization effect is the same as that of Example 1.

[0101] Example 3

[0102] The preparation method of Example 3 is basically the same as that of Example 1, except that 4-nitrophenylquinazolinone (CAS No. 4765-59-7) is used instead of phenylquinazolinone in Example 1, and a 4-nitrophenylquinazolinone probe solution of the same concentration is prepared. As shown in Table 1, 4-nitrophenylquinazolinone shows double emission peaks at 388 nm and 503 nm before interacting with lithium metal, presenting white fluorescence; 4-nitrophenylquinazolinone shows a single emission peak at 399 nm after interacting with lithium metal, presenting blue fluorescence, and the imaging characterization effect is the same as that of Example 1.

[0103] Example 4

[0104] The preparation method of Example 4 is basically the same as that of Example 1, except that 4-formylphenylquinazolinone (CAS No. 1801530-64-2) is used instead of phenylquinazolinone in Example 1, and a 4-formylphenylquinazolinone probe solution of the same concentration is prepared. As shown in Table 1, 4-formylphenylquinazolinone shows double emission peaks at 394 nm and 511 nm before interacting with lithium metal, presenting white fluorescence; 4-formylphenylquinazolinone shows a single emission peak at 400 nm after interacting with lithium metal, presenting blue fluorescence, and the imaging characterization effect is the same as that of Example 1.

[0105] Example 5

[0106] The preparation method of Example 5 is basically the same as that of Example 1, except that triphenylaminophenylquinazolinone (CAS No. 1396108-98-7) is used instead of phenylquinazolinone in Example 1, and a triphenylaminophenylquinazolinone probe solution of the same concentration is prepared. As shown in Table 1, triphenylaminophenylquinazolinone shows double emission peaks at 405 nm and 540 nm before interacting with lithium metal, presenting white fluorescence; triphenylaminophenylquinazolinone shows a single emission peak at 422 nm after interacting with lithium metal, presenting blue fluorescence, and the imaging characterization effect is the same as that of Example 1.

[0107] As can be seen from the test results of Examples 2-5, modifying the molecular skeleton of quinazolinone derivatives with different numbers and types of substituents does not affect the interaction between the substance and lithium metal, nor does it affect the electrode imaging characterization capability of the substance, and it can achieve precise modulation of fluorescence emission wavelength and intensity.

[0108] Example 6

[0109] The preparation method of Example 6 is basically the same as that of Example 1, except that 4-pyridylquinazolinone (CAS No. 6484-23-7) is used instead of phenylquinazolinone in Example 1 to prepare a 4-pyridylquinazolinone probe solution of the same concentration. As shown in Table 1, 4-pyridylquinazolinone exhibits a double emission peak before interacting with lithium metal, located at 400 nm and 536 nm, respectively, showing white fluorescence; after interacting with lithium metal, 4-pyridylquinazolinone exhibits a single emission peak, located at 398 nm, showing blue fluorescence, and the imaging characterization effect is no different from that of Example 1.

[0110] Example 7

[0111] The preparation method of Example 7 is basically the same as that of Example 1, except that 2-furanylquinazolinone (CAS No. 26059-84-7) is used instead of phenylquinazolinone in Example 1 to prepare a 2-furanylquinazolinone probe solution of the same concentration. As shown in Table 1, 2-furanylquinazolinone exhibits a double emission peak before interacting with lithium metal, located at 403 nm and 537 nm, respectively, showing white fluorescence; after interacting with lithium metal, 2-furanylquinazolinone exhibits a single emission peak, located at 399 nm, showing blue fluorescence, and the imaging characterization effect is no different from that of Example 1.

[0112] As can be seen from the test results of Examples 6 and 7, in addition to the benzene ring, the R1 group in the molecular skeleton of the quinazolinone derivative can be replaced with other aromatic rings or heteroaromatic ring substituents. Such modifications do not affect the interaction effect of this type of substance with lithium metal, do not affect the electrode imaging characterization capability of this type of substance, and can achieve precise modulation of fluorescence emission wavelength and intensity.

[0113] Comparative Example 1

[0114] The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that quinazolinone (CAS No. 491-36-1) is used instead of phenylquinazolinone in Example 1 to prepare a quinazolinone probe solution of the same concentration. The fluorescence spectra of quinazolinone before and after interaction with lithium metal are shown below. Figure 6 As shown. By Figure 6 (a) It can be seen that quinazolinone showed no obvious fluorescence signal before reacting with lithium metal; Figure 6(b)It can be known that the emission peak after the quinazolinone reacts with lithium metal is weak, and it is difficult to realize the detection of different components on the surface of lithium metal negative electrode. It is illustrated that R1 in the molecular structure of quinazolinone derivative needs to be aryl or heteroaryl, so as to realize the improvement of fluorescence yield and realize the detection of components on the surface of lithium metal negative electrode.

[0115] Table 1

[0116]

[0117]

[0118] Each technical feature of the above-described embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of each technical feature in the above-described embodiments are not described, however, as long as the combinations of the technical features do not exist contradictory, it should be considered that they are within the scope of the present disclosure.

[0119] The above-described embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims, and the description and drawings can be used to explain the scope of the claims.

Claims

1. A method for detecting the surface composition of a lithium metal anode, characterized in that, The lithium metal negative electrode is a lithium metal negative electrode after charge-discharge cycle in a lithium battery, and the method comprises the following steps: The quinazolinone derivative is used as a fluorescent probe to detect the components on the surface of the lithium metal negative electrode; the structural formula of the quinazolinone derivative is shown in formula I: Formula I, R1 is a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group; R2~R5 are independently selected from one or more of -H, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, a substituted or unsubstituted arylamine group, an imide group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted heterocyclic group, halogen, an amino group, a nitro group, a cyano group, an isocyano group, an acyl group, an alkyl group, an alkylene group, a heteroalkyl group, an alkenyl group, an alkenylene group, an alkynyl group, an alkynylene group, an ester group and an alkoxy group; The detection items of the detection include one or more of deposited lithium, by-products, lithium dendrites, dead lithium and solid electrolyte interface films on the surface of the lithium metal negative electrode; The by-products include lithium salts and / or polymers, the lithium salts include one or more of lithium fluoride, lithium chloride, lithium acetate, lithium carbonate, lithium hydroxide, lithium oxide and lithium alcoholate, and the polymers include one or more of polyvinyl carbonate, polycarbonate and polypropylene.

2. The detection method of claim 1, wherein, R1is substituted or unsubstituted C6-C10aryl, or substituted or unsubstituted heteroaryl having 5 to 10 ring atoms; 16 R1is substituted or unsubstituted C6-C10aryl, or substituted or unsubstituted heteroaryl having 5 to 10 ring atoms; 13 R1is substituted or unsubstituted C6-C10aryl, or substituted or unsub R2-R5are each independently selected from the group consisting of -H, one or more of substituted or unsubstituted C6-Cι2aryl, substituted or unsubstituted C3-C8cycloalkyl, substituted or unsubstituted Cι-C6alkyl, substituted or unsubstituted C6-C12arylamino, imidate, halogen, amino, nitro, cyano, isocyano, acyl, alkyl and alkoxy. 18 R2-R5are each independently selected from the group consisting of -H, one or more of substituted or unsubstituted C6-Cι2aryl, substituted or unsubstituted C3-C8cycloalkyl, substituted or unsubstituted Cι-C6alkyl, substituted 3. The detection method of claim 2, wherein, R1 is a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted anthracene group, a substituted or unsubstituted phenanthrene group, a substituted or unsubstituted pyrene group, a substituted or unsubstituted pyridine group, a substituted or unsubstituted pyrimidine group, a substituted or unsubstituted pyrazine group, a substituted or unsubstituted s-triazine group, a substituted or unsubstituted furan group, a substituted or unsubstituted thiophene group, a substituted or unsubstituted pyrrole group, a substituted or unsubstituted pyrazole group, a substituted or unsubstituted imidazole group, a substituted or unsubstituted oxazole group, or a substituted or unsubstituted thiazole group. R2~R5 are independently selected from one or more of -H, a nitro group, a formyl group, a triphenylamine group, a methoxy group and a maleimide group.

4. The detection method of claim 3, wherein, R1 is a substituted or unsubstituted phenyl group.

5. The detection method as described in claim 1, characterized in that, The quinazolinone derivative includes one or more of a phenyl quinazolinone, a 3-methoxyphenyl quinazolinone, a 4-nitrophenyl quinazolinone, a 4-formylphenyl quinazolinone, a triphenylamine phenyl quinazolinone, a 4-pyridyl quinazolinone and a 2-furyl quinazolinone.

6. The detection method as described in claim 1, characterized in that, The step of detecting comprises: Preparation of a probe solution containing the quinazolinone derivative; Contacting the probe solution with the surface of the lithium metal negative electrode, and performing fluorescent testing on the surface of the lithium metal negative electrode to detect the components on the surface of the lithium metal negative electrode.

7. The detection method of claim 6, wherein, The step of performing fluorescent testing comprises: Irradiating the surface of the lithium metal negative electrode with excitation light, and qualitatively analyzing the components on the surface of the lithium metal negative electrode according to the fluorescent signal distribution on the surface of the lithium metal negative electrode; And / or, irradiating the surface of the lithium metal negative electrode with excitation light, and quantitatively analyzing the components on the surface of the lithium metal negative electrode according to the fluorescent intensity difference of different distribution regions on the surface of the lithium metal negative electrode.

8. The detection method of claim 7, wherein, The solvent used in the probe solution includes one or more of an ether solvent, an alkane solvent, a furan solvent, a ketone solvent and a nitrile solvent.

9. The method of claim 7, wherein the detecting is performed by a method selected from the group consisting of mass spectrometry, nuclear magnetic resonance, and chromatography. The excitation light is ultraviolet light with a wavelength of 300 nm to 365 nm.

10. The method of claim 6, wherein the detecting is performed by a method selected from the group consisting of mass spectrometry, nuclear magnetic resonance, and chromatography. The concentration of the quinazolinone derivative in the probe solution is 0.5 mg / mL to 5 mg / mL.

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