Application of hydroxyl-modified chalcone molecules as probes in the detection of carbon material negative electrodes

Abstract

The application provides application of a hydroxyl-modified chalcone molecule as a probe in detection of a carbon material negative electrode, and a detection object of the detection includes lithium intercalation of the carbon material negative electrode. When the hydroxyl-modified chalcone molecule as the probe is applied in the detection of the carbon material negative electrode, visual observation and quantitative detection of uneven lithium intercalation in the carbon material negative electrode can be realized.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of batteries, in particular to application of a hydroxyl-modified chalcone molecule as a probe in detection of a carbon material negative electrode. BACKGROUND

[0002] Lithium ion batteries are an important energy storage device and have been widely used in electric vehicles, smart phones and other fields. In the current global greenhouse gas emissions and energy crisis, it is of great significance to develop efficient and environmentally friendly lithium ion batteries. In recent years, the research focus in the field of lithium ion batteries mainly concentrates on improving the energy density of the battery, prolonging the service life of the battery, improving the safety, and the like. Among them, the safety hazards of lithium ion batteries are mainly reflected in the management and monitoring of the battery, the optimization of the cell structure, and the stability of the negative electrode material under high state of charge.

[0003] Taking the most commonly used graphite negative electrode in commercial lithium ion batteries as an example, in the charging process of the lithium ion battery, lithium ions are embedded in the graphite layered structure to form a graphite intercalated compound, also known as a lithium carbon compound or lithium intercalation, and when charged to the full state, it is LiC6. Under the cycle conditions of fast charging, overcharging, low temperature and the like, the embedded lithium region is unevenly distributed, and often exhibits a local lithium ion concentration that is too high when the SOC is less than 100%. The uneven embedded lithium phenomenon directly leads to the rated capacity attenuation and local overheating of the negative electrode. In addition, the abnormal enrichment of embedded lithium makes lithium ions more likely to be deposited at this location, and the formation of lithium deposition has a great influence on the stability and safety of the battery cycle. Therefore, the direct imaging and characterization means for the uneven embedded lithium phenomenon in the negative electrode of the lithium ion battery is one of the important research targets for the interface of the carbon-based negative electrode.

[0004] In view of the embedded lithium phenomenon of the lithium ion battery in the cycle process, there are currently many characterization or detection technology researches, which can be roughly divided into two categories of physical methods and electrochemical methods, but the existing methods all lack direct observation and intuitive results, and cannot simultaneously realize direct observation and quantitative detection of the embedded lithium region and relative abundance in the carbon material negative electrode, and cannot provide clear, intuitive, visual and quantitative characterization results for analyzing the uneven embedded lithium distribution in the carbon material negative electrode. Therefore, it is urgent to develop a method for visually imaging and quantitatively analyzing the uneven embedded lithium phenomenon on the surface of the carbon material negative electrode. SUMMARY

[0005] Based on this, the application provides application of a hydroxyl-modified chalcone molecule as a probe in detection of a carbon material negative electrode, which can realize visual observation and quantitative detection of the uneven embedded lithium phenomenon in the carbon material negative electrode.

[0006] The first aspect of the present application provides an application of a hydroxyl-modified chalcone molecule as a probe in detection of a carbon material negative electrode, wherein the detection object of the detection includes intercalation lithium of the carbon material negative electrode.

[0007] In some embodiments of the present application, the hydroxyl-modified chalcone molecule has a structural formula as shown in the following formula (1):

[0008]

[0009] In formula (1), at least one of R1-R5 and R1'-R5' is a hydroxyl group, and the rest are each independently selected from one or more of hydrogen atom, alkyl group, cycloalkyl group, alkoxy group, alkenyl group, alkynyl group, heteroalkyl group, heterocyclic group, amino group, halogen, alkylene group, alkenylene group, alkynylene group, and alkylamino group, and optionally one or more of hydrogen atom, amino group, and halogen.

[0010] In some embodiments of the present application, the hydroxyl-modified chalcone molecule includes at least one of the following formula (2) and formula (3):

[0011]

[0012]

[0013] In some embodiments of the present application, the carbon material used by the carbon material negative electrode includes one or more of artificial graphite, natural graphite, hard carbon, soft carbon, carbon nanotube, and graphene.

[0014] In some embodiments of the present application, the carbon material used by the carbon material negative electrode includes one or more of artificial graphite, natural graphite, and graphene.

[0015] In some embodiments of the present application, the intercalation lithium of the carbon material negative electrode includes a graphite intercalation compound LiC x , x≥6.

[0016] In some embodiments of the present application, when the detection is performed, the hydroxyl hydrogen atom in the hydroxyl-modified chalcone molecule is replaced by lithium ion in the graphite intercalation compound to form a chalcone lithium salt;

[0017] Optionally, the chalcone lithium salt includes at least one of the following formula (4) and formula (5):

[0018]

[0019] In some embodiments of the present application, when the detection is performed, the hydroxyl-modified chalcone molecule is used as a probe in the form of a solution,

[0020] Optionally, the mass concentration of the hydroxyl-modified chalcone molecule in the solution is 0.1 mg / mL to 5 mg / mL, and further optionally 0.5 mg / mL to 4.5 mg / mL.

[0021] In some embodiments of the present application, the organic solvent contained in the solution comprises one or more of diethyl ether, tetrahydrofuran, acetone, n-hexane, and cyclohexane.

[0022] In some embodiments of the present application, the battery comprising the carbon material negative electrode comprises one or more of a lithium cobaltate battery, a lithium nickelate battery, a lithium iron phosphate battery, and a lithium manganese dioxide battery.

[0023] The hydroxyl-modified chalcone molecule provided by the present application is used as a probe in the detection of a carbon material negative electrode. The detection object includes lithium intercalation of the carbon material negative electrode. The intercalation compound formed after the hydroxyl-modified chalcone molecule intercalates lithium can achieve rapid and sufficient reaction, and the state changes from no fluorescence before reaction to bright yellow fluorescence emission after reaction. Thus, the probe can specifically mark the distribution and relative concentration of lithium ions in the negative electrode, and the negative electrode region without intercalated lithium ions does not exhibit an "open" fluorescence response, thereby enabling visualization observation and quantitative detection of lithium intercalation in the carbon material negative electrode. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A fluorescence change diagram of the o-hydroxy chalcone molecule as a probe of an embodiment of the present application after interaction with lithium metal.

[0025] Figure 2 A fluorescence spectrum of the o-hydroxy chalcone molecule of an embodiment of the present application before and after interaction with lithium metal.

[0026] Figure 3 A nuclear magnetic resonance hydrogen spectrum (H NMR) of the o-hydroxy chalcone molecule of an embodiment of the present application before and after interaction with lithium metal. 1 H NMR).

[0027] Figure 4 A fluorescence stability spectrum of the o-hydroxy chalcone molecule of an embodiment of the present application before and after interaction with lithium metal.

[0028] Figure 5 A fluorescence image of the o-hydroxy chalcone molecule in Example 1 after interaction with a cycled graphite negative electrode.

[0029] Figure 6 Fluorescence spectra of the o-hydroxy chalcone molecule (a) in Example 2 and the chalcone molecule (b) in Comparative Example 1, respectively, before and after interaction with a cycled graphite negative electrode. DETAILED DESCRIPTION

[0030] For the purposes of this application, the application will now be described more fully with reference to the accompanying drawings. The preferred embodiments of the application are shown in the drawings. However, the application can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the application to those skilled in the art.

[0031] For the sake of brevity, the application often directs only a single value for a given, but it is intended that the scope of the application encompasses equivalents between different upper and lower limits. Unless otherwise stated, all ranges include all the sub-ranges within the range. All references are incorporated by reference herein in their entirety. In case of conflict between the disclosure of the specification and the appended claims, the appended claims shall control.

[0032] Unless defined otherwise, all technical and scientific terms and any acronyms used herein have the same meanings as commonly understood by one of ordinary skill in the art in the field of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. The terms "comprises", "comprising", "includes", "including", "contains", "containing" and any variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises, includes and / or contains an item or a list of items who does not also contain an item does not (for reasons of non- exclusivity) include, or is not essential to, the process, method, article, or apparatus. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the application and does not pose a

[0033] The foregoing summary of the application does not necessarily describe every embodiment of the application. Additional illustrative embodiments of the application are described below. In various instances, guidance is provided by a series of examples that can be used in various combinations. In each instance, the recitation is merely representative of a group, and should not be construed as exhaustive.

[0034] Unless otherwise indicated, the terms or phrases used herein have the following meanings:

[0035] The term "alkyl" refers to saturated hydrocarbons comprising primary (normal) carbon atoms, or secondary carbon atoms, or tertiary carbon atoms, or quaternary carbon atoms, or a combination thereof. Phrases comprising this term, for example, "Ci-C9alkyl" refers to alkyl groups comprising from 1 to 9 carbon atoms, each occurrence of which can be independently C1alkyl, C2alkyl, C3alkyl, C4alkyl, C5alkyl, C6alkyl, C7alkyl, C8alkyl, or C9alkyl. 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(CH3)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).

[0036] The term "cycloalkyl" refers to a non-aromatic hydrocarbon containing ring carbon atoms, which can be monocyclic cycloalkyl, or spirocyclic cycloalkyl, or bridged cycloalkyl. Phrases containing this term, e.g., "C3-C9 cycloalkyl" means a cycloalkyl group containing 3 to 9 carbon atoms, which can be, independently at each occurrence, C3 cycloalkyl, C4 cycloalkyl, C5 cycloalkyl, C6 cycloalkyl, C7 cycloalkyl, C8 cycloalkyl, or C9 cycloalkyl. Suitable examples include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl. Additionally, "cycloalkyl" can also contain one or more double bonds, representative examples of cycloalkyl groups containing double bonds include cyclopentenyl, cyclohexenyl, cyclohexadienyl, and cyclobutadienyl.

[0037] The term "alkoxy" refers to a group having the formula -O-alkyl, i.e., an alkyl group, as defined above, attached to the parent structure through an oxygen atom. Phrases containing this term, e.g., "C1-C9 alkoxy" means that the alkyl portion contains 1 to 9 carbon atoms, which can be, independently at each occurrence, C1 alkoxy, C4 alkoxy, C5 alkoxy, C6 alkoxy, C7 alkoxy, C8 alkoxy, or C9 alkoxy. Suitable examples include, but are not limited to, methoxy (-O-CH3 or -OMe), ethoxy (-O-CH2CH3 or -OEt), and t-butoxy (-O-C(CH3)3 or -OtBu).

[0038] "Alkenyl" refers to a hydrocarbon containing a carbon-carbon sp 2 The term "alkyl" refers to a straight or branched hydrocarbon chain containing only carbon and hydrogen. Phrases containing this term, e.g., "C1-C9 alkyl" means that the alkyl group contains 1 to 9 carbon atoms, which can be, independently at each occurrence, C1 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, C7 alkyl, C8 alkyl, or C9 alkyl. Suitable examples include, but are not limited to, methyl (-CH3), ethyl (-CH2CH3), n-propyl (-CH2CH2CH3), n-butyl (-CH2CH2CH2CH3), n-pentyl (-CH2CH2CH2CH2CH3), and n-hexyl (-CH2CH2CH2CH2CH2CH3).

[0039] "Alkenyl" refers to a hydrocarbon containing a carbon-carbon sp

[0040] "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 this term, such as “C1-C9 heteroalkyl”, refer to heteroalkyl groups containing 1 to 9 carbon atoms, and each time they appear, they can be independently C2 heteroalkyl, C3 heteroalkyl, C4 heteroalkyl, C5 heteroalkyl, C7 heteroalkyl, C8 heteroalkyl, or C9 heteroalkyl.

[0041] "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 an N atom, O atom, S atom, etc., and can be a saturated ring or a partially unsaturated ring. Phrases containing this term, such as "C4-C9 heterocyclic group," refer to heterocyclic groups containing 4 to 9 carbon atoms, and each occurrence can be independently C4, C6, C7, C8, or C9 heteroalkyl. Suitable examples include, but are not limited to: dihydropyridyl, tetrahydropyridyl (piperidinyl), tetrahydrothiophenyl, sulfur-oxidized tetrahydrothiophenyl, tetrahydrofuranyl, tetrahydroquinolinyl, tetrahydroisoquinolinyl, and dihydroindolyl.

[0042] "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.

[0043] "Halogen" or "halogen group" refers to F, Cl, Br or I.

[0044] Currently, there are methods to analyze the uneven lithium intercalation phenomenon at the graphite anode after cycling using solid-state fluorescent molecules (catechol tetraphenylethylene). However, the fluorescent molecule used in this method, catechol tetraphenylethylene, has intrinsic fluorescence and a higher fluorescence quantum yield than its lithium salt product, thus causing imaging interference. Furthermore, after deprotonation to form lithium salt, the catechol group is easily oxidized by air to quinones, thereby quenching the fluorescence signal and resulting in poor imaging timeliness.

[0045] To address the aforementioned technical problems, the inventors have proposed the following technical solution in this application. Currently, chalcones typically exhibit enzyme inhibitory, antifungal, and anticancer activities, but do not universally exhibit fluorescence emission. This application verifies the fluorescence "open" response of hydroxyl-modified chalcones before and after interaction with active lithium, and for the first time explores the application of chalcone molecules as probes in the detection of carbon anode materials, particularly in the detection of uneven lithium intercalation in carbon anode materials.

[0046] The first aspect of this application provides the application of hydroxyl-modified chalcone molecules as probes in the detection of carbon material anodes, wherein the detection target includes lithium intercalation in the carbon material anode.

[0047] It should be noted that hydroxyl-modified chalcone molecules refer to chalcone molecules in which at least one substituent site on the benzene ring is replaced by a hydroxyl group, and in addition to the site replaced by the hydroxyl group, the remaining substituent sites may also be optionally replaced by other substituent groups. Other substituent groups may include, but are not limited to, one or more of alkyl, cycloalkyl, alkoxy, alkenyl, alkynyl, heteroalkyl, heterocyclic, amino, halogen, alkylene, alkenylene, alkynylene, and alkylamino groups.

[0048] It should be noted that the carbon material negative electrode to be tested is the carbon material negative electrode of the battery after charging and discharging.

[0049] During recycling, carbon anodes undergo lithium intercalation, where lithium ions enter the interlayer spaces of the carbon material, forming highly reactive intercalation compounds, such as LiC. x (x≥6); Taking graphite anode as an example, lithium intercalation occurs in graphite anode during recycling, and lithium ions enter the interlayer gaps of graphite sheets to form lithium graphite intercalation compound (Li-GIC).

[0050] The application of hydroxyl-modified chalcone molecules as probes in the detection of lithium intercalation in carbon anodes provided in this application allows for rapid and complete reaction between the hydroxyl-modified chalcone molecules and the intercalated compounds formed after lithium intercalation. The chalcone molecules transform from a non-fluorescent state before the reaction to a state with bright yellow fluorescence emission after the reaction. Thus, the probe can specifically identify the distribution and relative concentration of lithium ions in the anode, while the anode region without lithium intercalation will not show an "open" fluorescence response. Therefore, it is possible to visualize and quantitatively detect the lithium intercalation phenomenon in carbon anodes.

[0051] Meanwhile, this application is the first fluorescent probe molecule with an "open" response mode to be used for the detection of carbon material anode interfaces, which expands the design ideas of fluorescent probe molecules in this type of application. It is simple and convenient to operate, has an "open" response mode, and therefore has high imaging contrast and sensitivity and wide applicability.

[0052] It should be noted that the "open" fluorescence response described in this application refers to the process of fluorescence from absence to presence, that is, the hydroxyl-modified chalcone molecule changes from a non-fluorescent state before the reaction to a bright yellow fluorescent emission state after the reaction. It is generally believed that the fluorescence change difference formed by the "open" response is more intuitive and precise, and is a more efficient response mode than "closed" or "shift" responses.

[0053] In some embodiments, the hydroxyl-modified chalcone molecule has the structural formula shown in formula (1):

[0054]

[0055] In formula (1), at least one of R1 to R5 and R1' to R5' is a hydroxyl group, and the others are each independently selected from one or more of hydrogen atom, alkyl, cycloalkyl, alkoxy, alkenyl, alkynyl, heteroalkyl, heterocyclic, amino, halogen, alkylene, alkenyl, alkyne, and alkylamino, and may be selected from one or more of hydrogen atom, amino and halogen.

[0056] It is understandable that in chalcone molecules with the above-mentioned structural formula and hydroxyl modification, the hydroxyl group refers to the phenolic hydroxyl group located on the benzene ring, which has high reactivity.

[0057] The hydroxyl-modified chalcone molecules provided in this application have the above-mentioned structural formula. The phenolic hydroxyl group in the molecular structure exhibits high reactivity, reacting rapidly and fully with the intercalation compound formed after lithium insertion. This results in a transformation from a non-fluorescent state before the reaction to a chalcone lithium salt exhibiting bright yellow fluorescence after the reaction. Thus, this hydroxyl-modified chalcone molecule, as a probe, can specifically identify the distribution and relative concentration of lithium ions in the negative electrode. The negative electrode region without lithium ion insertion will not exhibit an "open" fluorescence response, thereby enabling visual observation and quantitative detection of lithium insertion in carbon material negative electrodes.

[0058] In some embodiments, the hydroxyl-modified chalcone molecule includes at least one of the following formulas: (2) (ortho-hydroxy chalcone) and (3) (p-hydroxy chalcone):

[0059]

[0060] In some embodiments, the carbon material used in the carbon material negative electrode includes one or more of artificial graphite, natural graphite, hard carbon, soft carbon, carbon nanotubes, and graphene.

[0061] In some embodiments, the lithium intercalation of the carbon material anode includes the graphite intercalation compound LiC. x , x≥6.

[0062] In some embodiments, during the detection, the hydroxyl hydrogen atom in the hydroxyl-modified chalcone molecule is replaced by a lithium ion in the graphite intercalation compound to form a lithium chalcone salt.

[0063] In some embodiments, when the hydroxyl-modified chalcone molecules are ortho-hydroxy chalcone and p-hydroxy chalcone, the resulting lithium chalcone salts correspond to formulas (4) (ortho-hydroxy chalcone lithium salt) and (5) (p-hydroxy chalcone lithium salt), respectively:

[0064]

[0065]

[0066] In some embodiments, the battery containing the carbon material negative electrode includes one or more of lithium cobalt oxide batteries, lithium nickel oxide batteries, lithium iron phosphate batteries, and lithium manganese dioxide batteries.

[0067] A second aspect of this application also provides a method for detecting hydroxyl-modified chalcone molecules as probes in a carbon material anode, which may include the following steps:

[0068] S10. Mix hydroxyl-modified chalcone molecules with an organic solvent to form a probe solution;

[0069] S20. The probe solution is brought into contact with the surface of the carbon material negative electrode, the fluorescence of the carbon material negative electrode surface is observed, and the fluorescence intensity is measured.

[0070] S30. Based on the fluorescence intensity, the amount of lithium ions inserted into the carbon material anode is quantitatively analyzed.

[0071] Specifically, after a lithium-ion battery has undergone charge-discharge cycles, the battery can be disassembled, and an organic solution of fluorescent probe molecules can be sprayed onto the surface of a carbon anode. The fluorescence on the anode surface can then be directly observed under a handheld ultraviolet lamp. All luminescent areas are equivalent to lithium-ion intercalation regions. Furthermore, the fluorescence intensity can be measured using a fluorescence spectrometer, thereby enabling quantitative analysis of the relative abundance of lithium ions.

[0072] In some embodiments, the hydroxyl-modified chalcone molecule is used as a probe in solution form during the detection.

[0073] In some embodiments, the mass concentration of the hydroxyl-modified chalcone molecule in the solution is from 0.1 mg / mL to 5 mg / mL. For example, the mass concentration can be 0.1 mg / mL, 0.5 mg / mL, 0.8 mg / mL, 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL, or within any range of the above values. Optionally, the mass concentration is from 0.5 mg / mL to 4.5 mg / mL.

[0074] In some embodiments, the organic solvent contained in the solution includes one or more of diethyl ether, tetrahydrofuran, acetone, n-hexane, and cyclohexane.

[0075] It should be noted that the above-mentioned organic solvents are volatile inert organic solvents.

[0076] Taking a carbon material anode as a graphite anode, a graphite intercalation compound as the intercalation compound, and a hydroxyl-modified chalcone molecule as an ortho-hydroxy chalcone as an example, the changes in the reaction process are explained in detail below.

[0077] o-Hydroxychalcone (CAS No. 888-12-0) exhibits no fluorescence emission in either solution or solid state under 365 nm UV excitation, meaning it lacks intrinsic fluorescence and does not cause imaging interference. However, the product after reaction with lithium metal, the lithium salt of o-hydroxychalcone, displays a bright yellow fluorescence signal under 365 nm UV excitation (e.g., ...). Figure 1 The maximum emission peak is located at 539 nm (e.g., Figure 2 ).like Figure 3As shown, the phenolic hydroxyl peak at chemical shift 12.45 ppm disappears, indicating that the phenolic hydroxyl group is the reaction site, and the reaction is rapid and complete. The 1H NMR spectrum shows that active lithium destroys the phenolic hydroxyl structure in ortho-hydroxy chalcone (δ 11.2 ppm), resulting in a significant change in the fluorescence signal. Figure 4 As shown, the fluorescence intensity of the ortho-hydroxychalcone lithium salt remained at 97.7% after one hour of continuous excitation, exhibiting extremely strong anti-photobleaching properties, which is helpful for long-term imaging characterization of the negative electrode interface and provides high imaging timeliness.

[0078] The method provided in this application can not only quantitatively and visually identify the lithium-ion insertion distribution and relative abundance at the negative electrode, but also link the battery performance degradation and failure with the degree of lithium-ion enrichment and uneven distribution, thus providing a new approach and direction for the technical analysis of the causes of electrode performance degradation and the early prevention and warning of battery failure.

[0079] Example

[0080] The following are specific embodiments, which describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations within the scope of the disclosure of this application will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0081] Example 1

[0082] The application of an o-hydroxychalcone molecule (CAS No. 888-12-0) as a probe in the detection of graphite anodes, wherein the battery containing the graphite anode is a lithium-ion battery, the lithium-ion battery used is an NCM622|Gr soft-pack battery, the anode is graphite, the cathode is a ternary material of lithium nickel oxide / lithium cobalt oxide / lithium manganese oxide, the electrolyte is 1 mol / L LiPF6 / EC+DEC+EMC (mass ratio 1:1:1), and the separator is a commercial PE membrane.

[0083] The battery was subjected to charge-discharge cycles using Blue Electric equipment, employing a constant current (0.1C, 1C = 100mA) - constant voltage (4.2V, 0.02C cutoff) charging and constant current discharge (0.1C) mode for formation. Subsequently, it was charged to 50% state of charge (50% SOC) at a high rate of 1.0C, and the battery was disassembled to obtain the cycled graphite anode material.

[0084] A 1.0 mg / mL solution of o-hydroxychalcone in ether was then sprayed onto the surface of the recycled graphite anode. After the ether evaporated, the anode was irradiated under a 365 nm handheld UV lamp. The fluorescence image is shown below. Figure 5 As shown.

[0085] Example 2

[0086] Example 2 is similar to Example 1, except that: p-hydroxychalcone (CAS No. 2657-25-2) was used instead of o-hydroxychalcone at the same mass concentration. The fluorescence image is as follows. Figure 6 As shown in (a).

[0087] Comparative Example 1

[0088] Comparative Example 1 is similar to Example 1, except that chalcone (CAS No. 94-41-7) of the same mass concentration was used instead of o-hydroxychalcone. The fluorescence image is as follows. Figure 6 As shown in (b).

[0089] Depend on Figure 5 As can be seen, after the highly active graphite intercalation compound (i.e., lithium intercalation) reacts with o-hydroxychalcone, a non-uniform bright yellow fluorescent region is formed under a 365nm handheld UV lamp, creating a high-contrast, high-sensitivity fluorescence signal that is distinctly different from the surrounding environment. Therefore, the lithium-ion intercalation distribution at the negative electrode can be directly observed with the naked eye. After measuring the fluorescence intensity using a fluorescence spectrometer, the amount of lithium-ion intercalation can be quantitatively analyzed. When the battery is charged and discharged under different cycle numbers, different charge and discharge currents, different cycle temperatures, and different stress environments, this method can provide a visual analysis of the lithium-ion intercalation distribution at the negative electrode under various cycle conditions, and further establish a scientifically valuable pattern between the lithium intercalation phenomenon and various cycle conditions.

[0090] Depend on Figure 6 (a) It can be seen that p-hydroxychalcone (intrinsic) does not exhibit any fluorescence emission, i.e., it has no intrinsic fluorescence and will not cause imaging interference; after interacting with lithium metal (lithiation), the maximum emission peak is located at 542 nm, therefore it also has an "open" response mode, which can be used to detect the non-uniform lithium intercalation phenomenon in carbon material anodes. Figure 6 (b) It can be seen that chalcone does not exhibit any fluorescence emission before and after interacting with lithium metal (intrinsic and lithiation), so it cannot be used to detect the uneven lithium intercalation phenomenon of carbon material anodes, which also proves the necessity of phenolic hydroxyl groups in the structure of fluorescent probe molecules.

[0091] 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.

[0092] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope 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 this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. Application of a hydroxyl-modified chalcone molecule as a probe in the detection of carbon material negative electrodes, characterized in that, The detection object of the detection includes lithium intercalation of a carbon material negative electrode; The hydroxyl-modified chalcone molecule has a structural formula shown in the following formula (1): （1）， In formula (1), at least one of R1-R5 and R1'-R5' is a hydroxyl group, and the rest are each independently selected from one or more of a hydrogen atom, an alkyl group, a cycloalkyl group, an alkoxy group, an alkenyl group, an alkynyl group, a heteroalkyl group, a heterocyclic group, an amino group, a halogen, an alkylene group, an alkenylene group, an alkynylene group, and an alkylamino group.

2. Use of the hydroxyl-modified chalcone molecule according to claim 1 as a probe in the detection of carbon material negative electrodes, characterized in that, The hydroxyl-modified chalcone molecule includes at least one of the following formula (2) and formula (3): （2）， （3）。 3. Use of the hydroxyl-modified chalcone molecule according to claim 1 or 2 as a probe in the detection of carbon material negative electrodes, characterized in that, The carbon material used in the carbon material negative electrode includes one or more of artificial graphite, natural graphite, hard carbon, soft carbon, carbon nanotubes, and graphene.

4. The use of the hydroxyl-modified chalcone molecule as a probe in the detection of carbon material negative electrodes according to claim 3, characterized in that, The lithium intercalation of the carbon material negative electrode includes graphite intercalation compounds LiC x , x > 6.

5. Use of the hydroxyl-modified chalcone molecule according to claim 4 as a probe in the detection of carbon material negative electrodes, characterized in that, During the detection, the hydroxyl hydrogen atom in the hydroxyl-modified chalcone molecule is replaced by a lithium ion in the graphite intercalation compound to form a chalcone lithium salt; The chalcone lithium salt includes at least one of the following formula (4) and formula (5): （4）， （5）。 6. Use of the hydroxyl-modified chalcone molecule according to claim 1 or 2 as a probe in the detection of carbon material negative electrodes, characterized in that, During the detection, the hydroxyl-modified chalcone molecule is used as a probe in the form of a solution, The mass concentration of the hydroxyl-modified chalcone molecule in the solution is 0.1 mg / mL to 5 mg / mL.

7. Use of the hydroxyl-modified chalcone molecule according to claim 6 as a probe in the detection of carbon material negative electrodes, characterized in that, The mass concentration of the hydroxyl-modified chalcone molecule in the solution is 0.5 mg / mL to 4.5 mg / mL.

8. Use of the hydroxyl-modified chalcone molecule according to claim 6 as a probe in the detection of carbon material negative electrodes, characterized in that, The organic solvent contained in the solution includes one or more of diethyl ether, tetrahydrofuran, acetone, n-hexane, and cyclohexane.

9. Use of the hydroxyl-modified chalcone molecule according to claim 1 or 2 as a probe in the detection of carbon material negative electrodes, characterized in that, The battery containing the carbon material negative electrode includes one or more of a lithium cobaltate battery, a lithium nickelate battery, a lithium iron phosphate battery, and a lithium manganese dioxide battery.

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