Polymer matrix, polymer electrolyte, all-solid-state battery and nondestructive testing method

Abstract

Disclosed in the present application are a polymer matrix having both good electrochemical performance and fluorescence characteristics. The polymer matrix is obtained by labeling an end group of polyoxyethylene with a fluorescent molecule. By means of the modification of the end group of polyoxyethylene, the crystallinity of the polymer matrix is effectively reduced, and the polymer matrix is endowed with fluorescence characteristics, thereby providing a new method for the nondestructive testing of electrolytes and effectively solving the problem of electrolytes being difficult to observe. Moreover, the polymer matrix of the present application can greatly improve the electrochemical performance of a polymer electrolyte and inhibit lithium dendrites, thereby allowing the polymer electrolyte to have a wide voltage window. Further disclosed in the present application are a polymer electrolyte containing the polymer matrix, and an all-solid-state battery and a nondestructive testing method therefor. By applying the fluorescence characteristics of the polymer matrix to interface characterization of a battery, the nondestructive testing of a battery interface is achieved, the application range of a solid-state electrolyte is expanded, and a fluorescence characterization method can be applied to battery interface detection.

Description

Polymer matrix, polymer electrolyte, all-solid-state battery and non-destructive testing method TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and particularly relates to a polymer matrix, a polymer electrolyte, an all-solid-state battery and a non-destructive testing method. BACKGROUND

[0002] With the continuous expansion of the application range of electronic devices, the requirements for the endurance and safety performance of the batteries of the electronic devices are also increasing, and it becomes increasingly important to develop lithium ion batteries with higher energy density and safety.

[0003] The research and development in the art for improving safety has multiple branches, among which solid-state electrolytes have the advantages of being non-flammable, high thermal stability and good mechanical properties, and replacing liquid electrolyte with them has been proven to effectively solve the safety hazards of lithium ion batteries and improve the energy density. Polyethylene oxide (PEO) is considered to be a polymer electrolyte matrix with great application prospect due to its low cost and good compatibility with lithium metal. However, the ionic conductivity of PEO at room temperature is low (10 -6 S cm -1 ), and the electrochemical window of stable operation of PEO is narrow (<3.9V vs. Li / Li + ), which limits its application in high-voltage positive electrode materials.

[0004] At present, structural modification of the polymer matrix can effectively improve the ionic conductivity and electrochemical window of the electrolyte, thereby realizing high-voltage application. For example, the patent document with publication number CN 117976971 A discloses a preparation method of a modified polyolefin oxide-based solid-state electrolyte, which includes synthesis of the solid-state electrolyte and vacuum film forming process at T. The solid-state electrolyte includes an epoxy polymer substrate and components A and lithium salt dispersed therein; component A is a modified organic high-molecular polymer rich in hydroxyl groups; 0.5T0≤T0, T0 is the melting temperature of the epoxy polymer.

[0005] The above-mentioned prior art can reduce the crystallinity of the polyolefin oxide-based solid-state electrolyte to a certain extent and limit the movement of polyanion groups, which can improve the cycle performance. However, the solid-state battery assembled by the electrolyte prepared by the prior art cannot non-destructively observe the interface bonding condition of the solid-state electrolyte and its adjacent structural layer, which is crucial for revealing the interface mechanism of the solid-state battery and optimizing the interface performance.

[0006] Based on the above status quo, the present application aims to find a new PEO modification preparation method, and to realize the dual-function application of the electrolyte in electrochemical performance and interface characterization. SUMMARY

[0007] In view of the problems in the prior art, the polymer matrix with excellent electrochemical performance and fluorescence characteristics is provided to overcome the above technical problems existing in the prior art. The polymer electrolyte, the all-solid-state battery and the non-destructive testing method thereof comprising the polymer matrix are also disclosed.

[0008] The technical solution of the present application is implemented as follows:

[0009] The polymer matrix with excellent electrochemical performance and fluorescence characteristics is obtained by marking a fluorescent molecule at the end group of polyethylene oxide (PEO).

[0010] The present application effectively reduces the crystallinity of the polymer matrix by modifying the end group of polyethylene oxide, and endows it with fluorescence characteristics, providing a new method for non-destructive testing of electrolytes, effectively solving the problem that electrolytes are difficult to observe. At the same time, the polymer matrix of the present application can greatly improve the electrochemical performance of the polymer electrolyte and inhibit lithium dendrites, so that the polymer electrolyte has a wide voltage window.

[0011] Preferably, the preparation method of the fluorescent molecule comprises the following steps:

[0012] A-1) adding tetra-bromospirofluorene and 4-boronic acid ester-4',4'-dimethoxytriphenylamine with a mass ratio of 80-120:330-350 into an organic solvent and mixing thoroughly, then placing in an inert gas atmosphere with a temperature ≥100℃ and reacting for at least 2h, purifying to obtain an intermediate product;

[0013] A-2) adding boron tribromide dropwise into the intermediate product obtained in step A-1) under the condition that the ambient temperature is ≤0℃, until the color of the solution after reaction does not change, then continuing to stir for at least 3h to complete the reaction, washing, drying to obtain a fluorescent molecule.

[0014] Preferably, in step A-1), an appropriate amount of potassium carbonate and palladium tetraphenylphosphine are also added, and the main role of the potassium carbonate and palladium tetraphenylphosphine is to ensure the reaction environment.

[0015] Preferably, in step A-1), the organic solvent is a mixed solution of toluene, ethanol and water, and the volume ratio of toluene, ethanol and water is 7-9:0.5-1.5:0.5-1.5.

[0016] The inert gas is nitrogen or argon.

[0017] Preferably, in step A-2), the washing liquid used for washing is deionized water and dichloromethane.

[0018] Preferably, in step A-2), the specific operation of drying is drying in a vacuum drying box with a temperature ≥55℃ for ≥10h.

[0019] Preferably, the preparation method of the polymer matrix comprises the following steps:

[0020] B-1) Dissolve polyethylene oxide (PEO) and pyridine in an organic solvent under the condition of ambient temperature ≤0℃, add appropriate amount of phosphorus tribromide (PBr3) and react for at least 30 min, then increase the temperature to ≥75℃ and continue to react for at least 10 h;

[0021] B-2) After removing the excess solvent, add fluorescent molecules and potassium hydroxide, and then place in an inert gas atmosphere at a temperature of ≥60℃ for sufficient reaction for at least 10 h;

[0022] B-3) Neutralize the residual potassium hydroxide in the reaction solution, dialyze, remove most of the solvent, dry, and obtain the polymer matrix with excellent electrochemical performance and fluorescence characteristics.

[0023] Preferably, in step B-1), the mass ratio of polyethylene oxide, pyridine and phosphorus tribromide is 100-150:100-150:20-50.

[0024] Preferably, in step B-1), the organic solvent is acetonitrile.

[0025] Preferably, in step B-2), the mass ratio of polyethylene oxide and fluorescent molecules is 100-150:1; and the inert gas is nitrogen or argon.

[0026] Preferably, in step B-3), the residual potassium hydroxide is neutralized by adding dilute hydrochloric acid dropwise in the reaction solution.

[0027] Preferably, in step B-3), the drying is performed in a vacuum drying oven at ≥55℃ for ≥10 h.

[0028] The application also discloses a polymer electrolyte comprising the polymer matrix with excellent electrochemical performance and fluorescence characteristics.

[0029] The preparation method of the polymer electrolyte comprises the following steps:

[0030] C-1) Configure the polymer matrix and lithium salt in a molar ratio of EO:Li + =12-16:1 in an organic solvent under the atmosphere of inert gas, mix and stir for at least 12 h;

[0031] C-2) Pour the solution prepared in step C-1) into a mold, and then place in a vacuum environment at 60-80℃ for drying for 12-24 h to obtain the polymer electrolyte.

[0032] Preferably, in step C-1), the inert gas is nitrogen or argon.

[0033] The solid-state polymer electrolyte prepared in the application has excellent electrochemical performance, and the ionic conductivity at room temperature is about 1 order of magnitude higher than that of pure polyethylene oxide, and has more excellent electrochemical window and cycle stability, and can be applied to the field of lithium batteries.

[0034] In addition, the polymer electrolyte of the application can emit cyan blue fluorescence under ultraviolet excitation, so that its combination with adjacent structural layers can be viewed in the fluorescence mode of a microscope.

[0035] The solid-state polymer electrolyte of the application has dual functional application value in the fields of lithium battery application and non-destructive interface characterization, and provides a new technical solution for the related field through the combination of its ion conduction and fluorescence properties, and has certain practical application value.

[0036] Preferably, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide.

[0037] Preferably, in step C-1), the organic solvent is acetonitrile.

[0038] The application also discloses a full solid-state battery comprising the solid-state polymer electrolyte made of the polymer matrix.

[0039] Since lithium has good compatibility with PEO, preferably, the full solid-state battery is a full solid-state lithium metal battery, which comprises the polymer electrolyte, a positive electrode sheet and a lithium negative electrode sheet.

[0040] Preferably, the preparation method of the positive electrode sheet comprises the following steps:

[0041] S1, taking the positive electrode material, polyvinylidene fluoride and carbon black in a mass ratio of 7.5-8.5:0.5-1.5:0.5-1.5, and grinding and mixing;

[0042] S2, adding an appropriate amount of solvent to the ground mixture in S1, and continuing to grind until a uniform electrode slurry is formed;

[0043] S3, uniformly coating the electrode slurry in S2 on a carbon-coated aluminum foil to form a uniform electrode coating, and performing vacuum drying treatment at a temperature of 60-80℃ for 12h-24h;

[0044] S4, punching the sheet-shaped material after drying in S3 to prepare the positive electrode sheet.

[0045] Preferably, the positive electrode material is LiFePO4.

[0046] The application also discloses a nondestructive testing method suitable for the all-solid-state battery, wherein the all-solid-state battery comprises a solid electrolyte made of the polymer matrix or the polymer electrolyte.

[0047] The all-solid-state battery is placed in a fluorescence mode of a microscope for imaging observation to check whether black gaps exist in the solid-solid interface, so as to determine the combination tightness or interface change of the solid polymer electrolyte and the adjacent structure layer (generally, an electrode).

[0048] The application applies the fluorescence characteristics of the self-developed polymer electrolyte with fluorescence characteristics to the interface characterization of the battery, realizes the nondestructive testing of the battery interface, expands the application range of the solid electrolyte, and makes the fluorescence characterization method applicable to the battery interface detection. BRIEF DESCRIPTION OF DRAWINGS

[0049] Fig. 1 is an X-ray diffraction diagram of the polymer matrix "PEO-Spiro" and unmodified PEO prepared in Example 1;

[0050] Fig. 2 is a diagram of the front and back states of the polymer electrolyte prepared in the application under ultraviolet light irradiation;

[0051] Fig. 3 is a bright field image of the battery assembled by the polymer electrolyte prepared in the application under a microscope;

[0052] Fig. 4 is a fluorescence image of the battery assembled by the polymer electrolyte prepared in the application under the ultraviolet light mode of a microscope;

[0053] Fig. 5 is a room temperature lithium ion conductivity diagram of Examples 1 to 4 and Comparative Example 1;

[0054] Fig. 6 is a linear sweep voltammetry curve diagram of the test battery prepared in Example 2;

[0055] Fig. 7 is a cycle performance diagram of the lithium symmetric battery prepared in Example 2 and Comparative Example 1;

[0056] Fig. 8 is a charge-discharge cycle performance diagram of the lithium symmetric battery prepared in Example 2;

[0057] Fig. 9 is a current rate cycle curve diagram of the lithium symmetric battery prepared in Example 2;

[0058] Fig. 10 is a current rate cycle curve diagram of Example 5 and Comparative Example 2. DETAILED DESCRIPTION

[0059] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort fall within the scope of the present application.

[0060] Embodiment 1

[0061] A, the preparation method of the fluorescent molecule Spiro-TPA-O8 is as follows:

[0062] A-1) 100 mg of tetrabromospirofluorene (C 25 H 12 Br4), 341 mg of 4-boronate-4', 4'-dimethoxytriphenylamine (C 26 H 30 BNO4), 110 mg of K2CO3 and 20 mg of tetrakis triphenylphosphine palladium are sequentially added into a 10 ml mixed solution of toluene, ethanol and water in a volume ratio of 8:1:1, and then fully reacted for 3 h at 120°C under an inert gas (nitrogen) atmosphere;

[0063] The obtained product is purified by column chromatography to remove the incompletely reacted reactants and the insufficiently reacted product, and an intermediate product "Spiro-TPA-OCH3" is obtained.

[0064] A-2) Under the condition of an ice water bath, boron tribromide is added dropwise into the purified product Spiro-TPA-OCH3 until the color of the solution after the reaction has no change, and then continues to be stirred for 4 h to complete the reaction; after the reaction is completed, the deionized water and dichloromethane are washed several times, and then placed in a vacuum drying box to dry at 60°C for 12 h to obtain the product fluorescent molecule "Spiro-TPA-O8".

[0065] B, the preparation method of the polymer matrix PEO-Spiro with fluorescent properties is as follows:

[0066] B-1) 1.2 g of PEO and 1 ml of pyridine are dissolved in an appropriate amount of acetonitrile solvent, 0.2 ml of PBr3 is added after completely dissolved in an ice water bath, and then heated to 80°C to continue to react for 12 h after reacting for 30 min.

[0067] B-2) After the excess solvent of the solution after the reaction is removed by a rotary evaporator, 10 mg of Spiro-TPA-O8, 0.8 g of KOH, an appropriate amount of methanol and a small amount of N, N-dimethylformamide are added, and then uniformly mixed and reacted for 12 h at 70°C under an inert gas (nitrogen) environment.

[0068] B-3) The solution after reaction was dropped into 2 mol / L dilute hydrochloric acid to neutralize the residual KOH, dialyzed in deionized water for 3 days, then most of the solvent was removed by rotary evaporation, and then placed in a vacuum oven at 60°C for drying for 12h to obtain the polymer matrix "PEO-Spiro".

[0069] C. Preparation of polymer electrolyte

[0070] C-1) Under an argon environment, 1g of PEO-Spiro and the corresponding mass of lithium salt "lithium bis (trifluoromethanesulfonyl) imide" (LiTFSI) were weighed according to the molar ratio EO:Li + = 12:1, respectively, into 20ml of acetonitrile solvent and continuously stirred to mix, with a stirring time of 18h.

[0071] C-2) The solution was cast in a polytetrafluoroethylene mold, and then placed in a vacuum environment at 60°C for drying for 12h to obtain the polymer electrolyte film "PEO-Spiro-LiTFSI".

[0072] Example 2

[0073] Compared with Example 1, 1g of PEO-Spiro and the corresponding mass of lithium salt LiTFSI were weighed according to the molar ratio EO:Li + = 13:1, respectively.

[0074] Example 3

[0075] Compared with Example 1, 1g of PEO-Spiro and the corresponding mass of lithium salt LiTFSI were weighed according to the molar ratio EO:Li + = 14:1, respectively.

[0076] Example 4

[0077] Compared with Example 1, 1g of PEO-Spiro and the corresponding mass of lithium salt LiTFSI were weighed according to the molar ratio EO:Li + = 16:1, respectively.

[0078] Example 5

[0079] A full solid-state lithium metal battery

[0080] D) The preparation method of the positive electrode sheet of this example is as follows:

[0081] D-1) Lithium iron phosphate (LiFePO4), polyvinylidene fluoride (PVDF) and carbon black conductive agent (Super P) were uniformly mixed in a mass ratio of 8:1:1, then put into a mortar for manual grinding, the grinding time was 30 min, then a proper amount of N-methyl pyrrolidone (NMP) was added to form a slurry state, and the grinding was continued for 30 min, to prepare an electrode slurry;

[0082] The electrode slurry was coated on a carbon-coated aluminum foil to form an electrode sheet, then the electrode sheet was transferred to a vacuum drying oven and dried at 80°C for 12 h, and punched into a 12 mm diameter disc to prepare a positive electrode sheet.

[0083] 2) The polymer electrolyte film prepared in Example 2 was cut into a 12 mm disc, then assembled with the positive electrode sheet and lithium metal to prepare a LiFePO4│PEO-Spiro│Li all-solid-state lithium metal battery.

[0084] Comparative Example 1

[0085] This comparative example is compared with Example 4, the polymer matrix is PEO without end group modification, PEO and lithium salt "lithium bis-trifluoromethanesulfonimide" (LiTFSI) are mixed in a molar ratio of EO:Li + = 16:1 to prepare an electrolyte film "PEO-LiTFSI".

[0086] Comparative Example 2

[0087] This comparative example is compared with Example 5, the electrolyte film prepared in Comparative Example 1 is used to prepare a LiFePO4│PEO│Li battery.

[0088] Performance Test

[0089] 1. X-ray Diffraction Analysis

[0090] X-ray diffraction analysis was performed on unmodified PEO and the polymer matrix "PEO-Spiro" prepared in Examples 1 to 4 for comparison. The results are shown in Figure 1, taking Example 1 as an example. The diffraction peaks of PEO-Spiro are consistent with those of PEO, indicating that the long chain structure of the modified PEO-Spiro is still consistent with that of PEO as a whole, and the only difference is that the functional groups at both ends are replaced.

[0091] 2. Fluorescence Property Test

[0092] [Corrected according to Rule 91 on 11.02.2025] Figure 2(a) is a real picture of the polymer electrolyte film "PEO-Spiro-LiTFSI" prepared in Examples 1 to 4, and the results are shown in Figure 2(b) under ultraviolet light irradiation. It can be seen that the polymer electrolyte film "PEO-Spiro-LiTFSI" prepared in the present application exhibits fluorescence phenomenon under ultraviolet light irradiation. In actual visual observation, the polymer electrolyte film changes from light green to cyan blue, which clearly indicates that the polymer electrolyte film "PEO-Spiro-LiTFSI" prepared in the present application has fluorescence properties and can exhibit fluorescence phenomenon under the excitation of ultraviolet light.

[0093] 3. Research on non-destructive testing method based on fluorescence properties

[0094] The polymer electrolyte film "PEO-Spiro-LiTFSI" prepared in Example 2 was cut into a 16 mm disc in an Ar glove box, and then placed between two lithium sheets. By applying different pressing pressures, a lithium symmetrical battery "Sample A" with poor solid-solid interface contact and a lithium symmetrical battery "Sample B" with tight solid-solid interface contact were prepared.

[0095] 3-1) The above two samples were placed under the bright field image mode of the microscope for imaging observation.

[0096] The results are shown in Figure 3, where the two sides are lithium metal and the black part in the middle is the polymer electrolyte film "PEO-Spiro-LiTFSI". The results show that under the bright field image of the optical microscope, it is not possible to determine the contact degree of the polymer electrolyte film and the electrode of the two samples.

[0097] 3-2) The above two assembled lithium symmetrical batteries were placed under the fluorescence mode of the microscope for imaging observation.

[0098] The results are shown in Figure 4, which is the fluorescence bright field image of the above two samples under ultraviolet light excitation. In fluorescence optical image (a), it can be clearly seen that there is a black gap between the lithium electrode and the polymer electrolyte film of "Sample A" with poor solid-solid interface contact, and in fluorescence optical image (b), it can be seen that there is no obvious black gap between the lithium electrode and the polymer electrolyte film of "Sample B" with tight solid-solid interface contact.

[0099] In summary, the battery product with the polymer electrolyte film "PEO-Spiro-LiTFSI" of the present application can be irradiated with ultraviolet light under the fluorescence mode of the microscope, and the tightness of the polymer electrolyte film and the electrode can be determined by whether there is a black gap at the solid-solid interface, or the interface change can be observed, which is a non-destructive testing method.

[0100] 4. Room temperature ionic conductivity test

[0101] The polymer electrolyte film "PEO-Spiro-LiTFSI" prepared in Examples 1 to 4 and the electrolyte film "PEO-LiTFSI" prepared in Comparative Example 1 were cut into 10 mm round pieces in an Ar glove box, and then placed between two stainless steel sheets to form a blocked electrode as a test sample.

[0102] The test sample was subjected to an alternating current impedance test in an electrochemical workstation with a frequency range from high frequency to low frequency of 1 MHz to 0.1 Hz to obtain the room temperature ionic conductivity of the test sample.

[0103] The test results are shown in FIG. 5. The room temperature ionic conductivity of the electrolyte film of Comparative Example 1 is lower than that of Examples 1 to 4, i.e., the "PEO-Spiro" modified by the end group of the present application, not only enables the polymer electrolyte film to have fluorescent properties, but also improves the room temperature ionic conductivity of the PEO polymer electrolyte film, i.e., improves the electrochemical performance; on the other hand, as can be seen from FIG. 5, when the lithium salt addition amount is configured in a molar ratio of EO:Li + = 13:1, the room temperature ionic conductivity performance of the polymer electrolyte film prepared is the most excellent.

[0104] 5. Electrochemical window test

[0105] The polymer electrolyte film "PEO-Spiro-LiTFSI" prepared in Example 2 was cut into 10 mm round pieces in an Ar glove box, and then placed between a stainless steel sheet and a lithium sheet for battery assembly, and then a linear sweep voltammetry test was performed on the battery by an electrochemical workstation, with a test potential range of 0 V to 6.55 V and a scan rate of 1 mV / s.

[0106] The results are shown in FIG. 6. The electrochemical window of the polymer electrolyte film "PEO-Spiro-LiTFSI" prepared in Example 2 reaches more than 5 V, indicating that the "PEO-Spiro" modified by the end group of the present application effectively improves the electrochemical window of the polymer electrolyte film.

[0107] 6. Cycle performance test

[0108] The polymer electrolyte film "PEO-Spiro-LiTFSI" prepared in Example 2 and the electrolyte film "PEO-LiTFSI" prepared in Comparative Example 1 were both cut into 16 mm round pieces in an Ar glove box, and then placed between two lithium sheets to form lithium symmetric batteries.

[0109] The cycle performance test was performed in a Land test system with a current density of 0.1 mA / cm 2 , and the test process alternated between charging and discharging every half hour.

[0110] The results are shown in Figure 7. The lithium symmetric battery using the polymer electrolyte film prepared in Example 2 remained stable without short circuiting after 400 h of cycling, while the lithium symmetric battery using the electrolyte film of Comparative Example 1 had a short circuit, indicating that the PEO-Spiro modified by the end group of the application effectively improved the cycling performance of the polymer electrolyte film.

[0111] 7. Limiting current density test

[0112] The polymer electrolyte film "PEO-Spiro-LiTFSI" prepared in Example 2 and the electrolyte film "PEO-LiTFSI" prepared in Comparative Example 1 were each cut into a 16 mm disc and then placed between two lithium sheets to form lithium symmetric batteries.

[0113] The limiting current density was tested in a Land test system.

[0114] Figure 8 is a graph of the cycling performance of the lithium symmetric battery prepared in Example 2 at different current densities, and Figure 9 is a graph of the cycling performance of the lithium symmetric battery prepared in Comparative Example 1 at different current densities. As shown by comparing Figures 8 and 9, the limiting current density of the polymer electrolyte film prepared in Example 2 was 1.0 mA / cm 2 , while the limiting current density of the electrolyte film of Comparative Example 1 was only 0.5 mA / cm 2 , and the stable cycle did not exceed 100 h, which was a large gap from Example 2, indicating that the PEO-Spiro modified by the end group of the application could effectively increase the limiting current density of the polymer electrolyte film.

[0115] 8. Cycling performance test of all-solid-state lithium metal battery

[0116] The all-solid-state lithium metal batteries prepared in Example 5 and Comparative Example 2 were subjected to a cycling performance test at 45°C and 0.2C.

[0117] The results are shown in Figure 10. As shown in the figure, the LiFePO4│PEO-Spiro│Li all-solid-state lithium metal battery prepared in Example 5 had a discharge specific capacity of 145.2 mAh g -1 at 100 cycles, and a capacity retention rate of 94.6%; the LiFePO4│PEO│Li battery prepared in Comparative Example 2 had a discharge specific capacity of 108.3 mAh g -1 at 100 cycles, and a capacity retention rate of 71.6%.

[0118] The above examples and comparative examples prove the effectiveness of the application in improving the electrical properties of PEO-based polymer electrolytes and the pioneering application of the fluorescent interface characterization method in the field of lithium batteries from the performance comparison of the end groups of the polymers PEO before and after modification.

[0119] According to the disclosure and teaching of the above description, those skilled in the art of the present application can also make changes and modifications to the above embodiments, therefore, the present application is not limited to the specific embodiments disclosed and described above, and some modifications and changes of the present application should also fall within the protection scope of the claims of the present application. In addition, although some specific terms are used in the specification, these terms are only for convenience of description and do not constitute any limitation on the present application.

Claims

1. A polymer matrix possessing both excellent electrochemical performance and fluorescence properties, characterized in that, The fluorescent molecule is obtained by marking a fluorescent molecule at the end group of polyethylene oxide.

2. The polymer matrix with excellent electrochemical performance and fluorescent characteristics according to claim 1, characterized in that, The preparation method of the fluorescent molecule comprises the following steps: A-1) tetra-bromine spirofluorene and 4-boronic acid ester-4', 4'-dimethoxytriphenylamine with a mass ratio of 80-120:330-350 are added into an organic solvent and mixed thoroughly, and then are reacted in an inert gas atmosphere at a temperature of ≥100℃ for at least 2h, and then are purified to obtain an intermediate product; A-2) at an ambient temperature of ≤0℃, boron tribromide is added dropwise into the intermediate product obtained in step A-1) until the color of the solution after the reaction does not change, and then the reaction is continued to be stirred for at least 3h to be complete, and then the product is washed and dried to obtain the fluorescent molecule.

3. The polymer matrix with excellent electrochemical performance and fluorescent characteristics according to claim 1 or 2, characterized in that, The preparation method of the polymer matrix comprises the following steps: B-1) at an ambient temperature of ≤0℃, polyethylene oxide and pyridine are dissolved in an organic solvent, an appropriate amount of phosphorus tribromide is added, and the reaction is carried out for at least 30min, and then the temperature is increased to ≥75℃ to continue the reaction for at least 10h; B-2) after the excess solvent is removed, the fluorescent molecule and potassium hydroxide are added, and then the reaction is carried out in an inert gas atmosphere at a temperature of ≥60℃ for at least 10h; B-3) the residual potassium hydroxide in the reaction solution is neutralized, dialysis is carried out, most of the solvent is removed, and then drying is carried out to obtain the polymer matrix with excellent electrochemical performance and fluorescent properties.

4. The polymer matrix with excellent electrochemical performance and fluorescent characteristics according to claim 3, characterized in that, In step B-1), the mass ratio of the polyethylene oxide, pyridine and phosphorus tribromide is 100-150:100-150:20-50.

5. The polymer matrix with excellent electrochemical performance and fluorescent characteristics according to claim 3, characterized in that, In step B-2), the mass ratio of the polyethylene oxide and the fluorescent molecule is 100-150:

1.

6. A polymer electrolyte characterized by comprising: The polymer matrix according to any one of claims 1 to 5.

7. The polymer electrolyte according to claim 6, wherein The preparation method of the polymer electrolyte comprises the following steps: C-1) the polymer matrix and the lithium salt are arranged in a molar ratio EO:Li + = 12-16:1, in an organic solvent, under mixing and stirring for at least 12 h; C-2) the solution obtained in step C-1) is poured into a mold, and then is placed in a vacuum environment at a temperature of 60-80℃ for drying for 12-24h to obtain the polymer electrolyte.

8. An all-solid battery, characterized by, The solid-state electrolyte is made of the polymer matrix according to any one of claims 1 to 5.

9. The all-solid battery according to claim 8, characterized by, The all-solid-state battery is an all-solid-state lithium metal battery, and the all-solid-state lithium metal battery comprises the polymer electrolyte, a positive electrode sheet and a lithium negative electrode sheet.

10. A non-destructive testing method suitable for use in an all-solid-state battery, characterized by, The all-solid-state battery comprises the solid-state electrolyte made of the polymer matrix according to any one of claims 1 to 5. The all-solid-state battery is placed in a fluorescence mode of a microscope for imaging observation to check whether there is a black gap at a solid-solid interface, so as to judge the combination tightness or interface change of the solid-state polymer electrolyte and adjacent structure layers.

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