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

Abstract

The application discloses a polymer matrix with excellent electrochemical performance and fluorescence characteristics, which is obtained by marking a fluorescent molecule at the end group of polyethylene oxide, effectively reduces the crystallinity of the polymer matrix by modifying the end group of polyethylene oxide, and endows the polymer matrix with fluorescence characteristics, thereby providing a new method for nondestructive testing of electrolytes and effectively solving the problem that electrolytes are difficult to observe; meanwhile, the polymer matrix can greatly improve the electrochemical performance of the polymer electrolyte and inhibit lithium dendrites, so that the polymer electrolyte has a wide voltage window; the application further discloses a polymer electrolyte containing the polymer matrix, a full solid-state battery and a nondestructive testing method thereof, applies the fluorescence characteristics of the polymer matrix to interface characterization of the battery, realizes nondestructive testing of the battery interface, expands the application range of the solid-state electrolyte, and makes the fluorescence characterization method applicable to battery interface detection.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a polymer matrix, polymer electrolyte, all-solid-state battery, and non-destructive testing method. Background Technology

[0002] As the application scope of electronic devices continues to expand, the requirements for the battery life and safety performance of these devices are also increasing, making the development of lithium-ion batteries with higher energy density and safety increasingly important.

[0003] Research and development in this field to improve safety has multiple branches. Solid-state electrolytes, with their advantages of non-flammability, high thermal stability, and good mechanical properties, have been proven to effectively address safety concerns and improve energy density in lithium-ion batteries when used as a substitute for liquid electrolytes. Polyethylene oxide (PEO), with its low cost and good compatibility with lithium metal, is considered a promising polymer electrolyte matrix. However, PEO has a low ionic conductivity at room temperature (10⁻⁶). -6 Scm -1 Furthermore, PEO has a narrower electrochemical window for stable operation (<3.9V vs. Li / Li). + This limits its application in high-voltage cathode materials.

[0004] Currently, structural modification of the polymer matrix can effectively improve the ionic conductivity and electrochemical window of the electrolyte, thereby enabling high-voltage applications. For example, patent document CN 117976971 A discloses a method for preparing a modified oxidized polyolefin-based solid electrolyte, which includes the synthesis of the solid electrolyte and a vacuum film-forming process at temperature T. The solid electrolyte includes an epoxy polymer substrate and component A and a lithium salt dispersed therein; component A is a modified organic polymer rich in hydroxyl groups; 0.5T0≤T0, where T0 is the melting temperature of the epoxy polymer.

[0005] The aforementioned prior art can reduce the crystallinity of oxidized polyolefin-based solid electrolytes to a certain extent and restrict the movement of polyanionic groups, thereby improving their cycle performance. However, solid-state batteries assembled with electrolytes produced by this prior art cannot be observed non-destructively at the interface between the solid electrolyte and its adjacent structural layers. This is crucial for revealing the interface mechanism of solid-state batteries and optimizing interface performance.

[0006] Based on the above situation, the present invention aims to find a new method for preparing modified PEO, so as to realize the dual-functional application of electrolyte in electrochemical performance and interface characterization. Summary of the Invention

[0007] To address the problems in related technologies, this invention proposes a polymer matrix that combines excellent electrochemical performance and fluorescence properties, thereby overcoming the aforementioned technical issues in existing related technologies. This invention also discloses a polymer electrolyte comprising this polymer matrix, an all-solid-state battery, and a non-destructive testing method thereof.

[0008] The technical solution of this invention is implemented as follows:

[0009] A polymer matrix with both excellent electrochemical and fluorescent properties is obtained by labeling fluorescent molecules on the end groups of polyethylene oxide (PEO).

[0010] This invention effectively reduces the crystallinity of the polymer matrix and imparts fluorescence properties by modifying the end groups of polyethylene oxide, providing a new method for non-destructive testing of electrolytes and effectively solving the problem of difficult-to-observe electrolytes. At the same time, the polymer matrix of this invention can significantly improve the electrochemical performance of polymer electrolytes and suppress lithium dendrites, giving polymer electrolytes a wide voltage window.

[0011] Preferably, the method for preparing the fluorescent molecule includes the following steps:

[0012] A-1) Tetrabromospirulin and 4-boronate-4',4'-dimethoxytriphenylamine in a mass ratio of 80-120:330-350 were added to an organic solvent and mixed thoroughly. The mixture was then placed in an inert gas atmosphere at a temperature ≥100℃ and reacted for at least 2 hours. After purification, an intermediate product was obtained.

[0013] A-2) Under ambient temperature ≤0℃, boron tribromide is added dropwise to the intermediate product obtained in step A-1) until the color of the solution after the reaction does not change. Stirring is continued for at least 3 hours to ensure complete reaction. The solution is then rinsed, dried, and fluorescent molecules are obtained.

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

[0015] Preferably, in step A-1), the organic solvent is a mixed solution of toluene, ethanol and water, wherein 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 rinsing solution used is deionized water and dichloromethane.

[0018] Preferably, in step A-2), the drying operation specifically involves drying in a vacuum drying oven at ≥55°C for ≥10 hours.

[0019] Preferably, the method for preparing the polymer matrix includes the following steps:

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

[0021] B-2) After removing excess solvent, add fluorescent molecules and potassium hydroxide, and then place in an inert gas atmosphere at a temperature ≥60℃ to react fully for at least 10 hours;

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

[0023] Preferably, in step B-1), the mass ratio of the 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 the polyethylene oxide to the fluorescent molecules is 100-150:1; 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 to the reaction solution.

[0027] Preferably, in step B-3), the drying operation specifically involves drying in a vacuum drying oven at ≥55°C for ≥10 hours.

[0028] The present invention also discloses a polymer electrolyte comprising the above-mentioned polymer matrix that has both excellent electrochemical performance and fluorescence properties.

[0029] The preparation method of the above-mentioned polymer electrolyte includes the following steps:

[0030] C-1) Under an inert gas atmosphere, the polymer matrix and lithium salt are mixed in a molar ratio of EO:Li + Prepare a mixture of 12 to 16:1 and mix it in an organic solvent for at least 12 hours.

[0031] C-2) The solution obtained in step C-1) is poured into a mold and then dried in a vacuum environment at 60-80°C for 12-24 hours to obtain the polymer electrolyte.

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

[0033] The solid polymer electrolyte prepared by this invention has excellent electrochemical performance. Its ionic conductivity at room temperature is about one order of magnitude higher than that of pure polyethylene oxide, and it has a better electrochemical window and cycle stability, making it applicable to the field of lithium batteries.

[0034] Furthermore, the polymer electrolyte of the present invention can emit cyan-blue fluorescence under ultraviolet excitation, thus allowing its bonding with adjacent structural layers to be observed under a microscope in fluorescence mode.

[0035] The solid polymer electrolyte of this invention has dual-function application value in lithium battery applications and non-destructive interface characterization. By combining its ion conduction and fluorescence properties, it provides a new technical solution for related fields and has certain practical application value.

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

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

[0038] The present invention also discloses an all-solid-state battery comprising a solid polymer electrolyte made of the polymer matrix described above.

[0039] Since lithium has good compatibility with PEO, preferably, the all-solid-state battery is an all-solid-state lithium metal battery, which includes the polymer electrolyte, positive electrode and lithium negative electrode described above.

[0040] Preferably, the method for preparing the positive electrode sheet includes the following steps:

[0041] S1. Weigh the positive electrode material, polyvinylidene fluoride and carbon black conductor according to the mass ratio of 7.5~8.5∶0.5~1.5∶0.5~1.5, and grind and mix them.

[0042] S2. Add an appropriate amount of solvent to the mixture after grinding in S1, and continue grinding until a uniform electrode slurry is formed;

[0043] S3. The electrode paste from S2 is uniformly coated onto the carbon-coated aluminum foil to form a uniform electrode coating, and then vacuum dried at a temperature of 60-80°C for 12-24 hours.

[0044] S4. The dried sheet material from S3 is punched to form the positive electrode sheet.

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

[0046] The present invention also discloses a non-destructive testing method applicable to all-solid-state batteries, wherein the all-solid-state battery includes a solid electrolyte made of the above-mentioned polymer matrix or the above-mentioned polymer electrolyte;

[0047] The all-solid-state battery was placed in the fluorescence mode of a microscope for imaging observation to check whether there were black gaps at the solid-solid interface, thereby determining the degree of bonding between the solid polymer electrolyte and the adjacent structural layer (usually the electrode) or the interface changes.

[0048] This invention is based on a self-developed polymer electrolyte with fluorescent properties. By applying its fluorescent properties to the interface characterization of batteries, non-destructive testing of battery interfaces is achieved, expanding the application range of solid electrolytes and enabling fluorescent characterization methods to be applied to battery interface testing. Attached Figure Description

[0049] Figure 1 X-ray diffraction patterns of the polymer matrix "PEO-Spiro" prepared in Example 1 and unmodified PEO;

[0050] Figure 2 The polymer electrolyte prepared in this invention is shown in the before and after state diagrams under ultraviolet light irradiation.

[0051] Figure 3 Bright-field image of a battery assembled with the polymer electrolyte prepared in this invention under a microscope;

[0052] Figure 4 Fluorescence image of a battery assembled with the polymer electrolyte prepared in this invention under ultraviolet light mode in a microscope;

[0053] Figure 5 The following are room temperature lithium-ion conductivity graphs for Examples 1 to 4 and Comparative Example 1;

[0054] Figure 6 Linear scan volt-ampere curve of the test battery prepared in Example 2;

[0055] Figure 7 The graphs show the cycle performance of lithium symmetric batteries fabricated in Example 2 and Comparative Example 1.

[0056] Figure 8 This is a charge-discharge cycle performance diagram of a lithium symmetric battery fabricated in Example 2;

[0057] Figure 9 The current rate cycling curve of the lithium symmetric battery fabricated in Comparative Example 1 is shown.

[0058] Figure 10 The current ratio cycling curves for Example 5 and Comparative Example 2 are shown. Detailed Implementation

[0059] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0060] Example 1

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

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

[0063] The obtained product was purified by column chromatography to remove incompletely reacted reactants and products with insufficient reaction, yielding the intermediate product "Spiro-TPA-OCH3".

[0064] A-2) Under ice-water bath conditions, boron tribromide was added dropwise to the purified product Spiro-TPA-OCH3 until the color of the solution after the reaction did not change. Then, the mixture was stirred for another 4 hours to ensure complete reaction. After the reaction was complete, the mixture was washed several times with deionized water and dichloromethane and then dried in a vacuum drying oven at 60°C for 12 hours to obtain the 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) Dissolve 1.2g of PEO and 1ml of pyridine in an appropriate amount of acetonitrile solvent. After complete dissolution in an ice-water bath, add 0.2ml of PBr3. React for 30min and then heat to 80℃ to continue the reaction for 12h.

[0067] B-2) After removing excess solvent from the reaction solution using a rotary evaporator, add 10 mg of Spiro-TPA-O8, 0.8 g of KOH, an appropriate amount of methanol, and a small amount of N,N-dimethylformamide. Mix well and react at 70°C under an inert gas (nitrogen) environment for 12 h.

[0068] B-3) The solution after the reaction was added dropwise with 2 mol / L dilute hydrochloric acid to neutralize the residual KOH. The solution was dialyzed in deionized water for 3 days, then most of the solvent was removed by rotary evaporation. The solution was then dried in a vacuum oven at 60°C for 12 hours to obtain the polymer matrix “PEO-Spiro”.

[0069] C. Preparation of polymer electrolytes

[0070] C-1) Under argon atmosphere, molar ratio EO:Li + Weigh 1g of PEO-Spiro and the corresponding mass of lithium salt "lithium bis(trifluoromethanesulfonylimide)" (LiTFSI) into 20ml of acetonitrile solvent at a ratio of 12:1 and stir continuously for 12-24 hours.

[0071] C-2) The solution was poured into a polytetrafluoroethylene mold and then dried in a vacuum environment at 60°C for 12 hours to obtain the polymer electrolyte membrane "PEO-Spiro-LiTFSI".

[0072] Example 2

[0073] Compared with Example 1, this embodiment has a molar ratio of EO:Li + Weigh out 1g of PEO-Spiro and the corresponding mass of lithium salt LiTFSI in a ratio of 13:1.

[0074] Example 3

[0075] Compared with Example 1, this embodiment has a molar ratio of EO:Li + Weigh 1g of PEO-Spiro and the corresponding mass of lithium salt LiTFSI in a ratio of 14:1.

[0076] Example 4

[0077] Compared with Example 1, this embodiment has a molar ratio of EO:Li + Weigh 1g of PEO-Spiro and the corresponding mass of lithium salt LiTFSI in a ratio of 16:1.

[0078] Example 5

[0079] A type of all-solid-state lithium metal battery

[0080] D) The method for preparing the positive electrode sheet in this embodiment is as follows:

[0081] D-1) Lithium iron phosphate (LiFePO4), polyvinylidene fluoride (PVDF) and carbon black conductive agent (Super P) are mixed evenly in a mass ratio of 8:1:1 and then placed in a mortar for manual grinding for 30 minutes. After grinding, an appropriate amount of N-methylpyrrolidone (NMP) is added to form a slurry. The slurry is then ground for another 30 minutes to obtain the electrode slurry.

[0082] Electrode paste is coated onto carbon-coated aluminum foil to form an electrode sheet. The electrode sheet is then transferred to a vacuum drying oven and vacuum dried at 80°C for 12 hours. It is then punched into a 12mm diameter disc to obtain the positive electrode sheet.

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

[0084] Comparative Example 1

[0085] Compared with Example 4, this comparative example uses PEO without end-group modification as the polymer matrix, with a molar ratio of EO:Li + The electrolyte membrane “PEO-LiTFSI” is prepared by mixing PEO and lithium salt “lithium bis(trifluoromethanesulfonylimide)” (LiTFSI) in a ratio of 16:1.

[0086] Comparative Example 2

[0087] Compared with Example 5, this comparative example uses the electrolyte membrane prepared in Comparative Example 1 to prepare a LiFePO4│PEO│Li battery.

[0088] Performance testing

[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 Example 1 as an example. Figure 1 As shown, the diffraction peaks of PEO-Spiro are consistent with those of PEO, indicating that the modified PEO-Spiro maintains the same long-chain structure as PEO, with the only difference being the replacement of functional groups at both ends.

[0091] 2. Fluorescence property test

[0092] Figure 2 (a) is a photograph of the polymer electrolyte membrane "PEO-Spiro-LiTFSI" prepared in Examples 1 to 4, irradiated with ultraviolet light, and the results are as follows. Figure 2 As shown in (b), the polymer electrolyte membrane is composed of Figure 2 (a) The pale green color turned into Figure 2 (b) The cyan-blue color indicates that the polymer electrolyte membrane "PEO-Spiro-LiTFSI" prepared in this invention has fluorescent properties and can exhibit fluorescence under ultraviolet light excitation.

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

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

[0095] 3-1) Place the two samples mentioned above in the bright field imaging mode of the microscope for imaging observation.

[0096] The results are as follows Figure 3 As shown, Figure 3 The two sides are lithium metal, and the black part in the middle is the polymer electrolyte membrane "PEO-Spiro-LiTFSI". The results show that under the bright field image of the optical microscope, it is impossible to determine the degree of contact between the polymer electrolyte membrane and the electrode of the two samples.

[0097] 3-2) The two assembled lithium symmetric batteries were placed in the fluorescence mode of a microscope for imaging observation.

[0098] The results are as follows Figure 4 As shown, Figure 4 The images show the bright-field fluorescence images of the two samples under ultraviolet light excitation. In fluorescence optical image (a), a black gap can be clearly seen between the lithium electrode and the polymer electrolyte membrane of "sample A", which has poor solid-solid interface contact. In fluorescence optical image (b), no obvious black gap can be seen between the lithium electrode and the polymer electrolyte membrane of "sample B", which has tight solid-solid interface contact.

[0099] In summary, the battery product incorporating the polymer electrolyte membrane "PEO-Spiro-LiTFSI" of the present invention can be tested by irradiating the product with ultraviolet light under the fluorescence mode of a microscope. The tightness of the bond between the polymer electrolyte membrane and the electrode can be determined by observing whether there are black gaps at the solid interface, or by observing changes at the interface. This is a non-destructive testing method.

[0100] 4. Room temperature ionic conductivity test

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

[0102] The test samples were subjected to AC impedance testing on an electrochemical workstation at a frequency range of 1MHz to 0.1Hz to obtain the room temperature ionic conductivity of the test samples.

[0103] Test results are as follows Figure 5 As shown, the electrolyte membrane of Comparative Example 1 has a lower room temperature ionic conductivity than that of Examples 1 to 4. This means that the "PEO-Spiro" modified with the end groups of this invention not only imparts fluorescent properties to the polymer electrolyte membrane but also improves the room temperature ionic conductivity of the PEO polymer electrolyte membrane, thus enhancing its electrochemical performance. On the other hand, from... Figure 5 It can be seen from the molar ratio EO∶Li + When the lithium salt addition ratio is 13:1, the polymer electrolyte membrane exhibits the best room temperature ionic conductivity.

[0104] 5. Electrochemical window testing

[0105] In an Ar glove box, the polymer electrolyte membrane "PEO-Spiro-LiTFSI" prepared in Example 2 was cut into 10 mm round pieces and placed between stainless steel and lithium sheets for battery assembly. Then, the battery was subjected to linear scanning voltammetry curve testing using an electrochemical workstation. The test potential range was 0 V to 6.55 V, and the scan rate was 1 m V / s.

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

[0107] 6. Cyclic performance test

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

[0109] Cyclic performance testing was conducted using the Land testing system at a current density of 0.1 mA / cm². 2 The test process involves alternating between charging and discharging every half hour.

[0110] The results are as follows Figure 7 As shown in the figure, the lithium symmetric battery using the polymer electrolyte membrane prepared in Example 2 remained stable after 400 hours of cycling without short circuit. The lithium symmetric battery using the electrolyte membrane of Comparative Example 1, as shown in the figure, experienced a short circuit. This indicates that the "PEO-Spiro" modified by the end group of the present invention effectively improves the cycling performance of the polymer electrolyte membrane.

[0111] 6. Limiting Current Density Test

[0112] In an Ar glove box, the polymer electrolyte membrane "PEO-Spiro-LiTFSI" prepared in Example 2 and the electrolyte membrane "PEO-LiTFSI" prepared in Comparative Example 1 were both cut into 16mm round pieces and then placed between two lithium sheets to form lithium symmetric batteries.

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

[0114] Figure 8 This is a graph showing the cycling performance of the lithium symmetric battery prepared in Example 2 at different current densities. Figure 9 The graph shows the cycling performance of the lithium symmetric battery prepared in Comparative Example 1 at different current densities, for comparison. Figure 8 and Figure 9 It can be seen that the limiting current density of the polymer electrolyte membrane prepared in Example 2 is 1.0 mA / cm². 2 The limiting current density of the electrolyte membrane in Comparative Example 1 is only 0.5 mA / cm². 2 The stable cycling time was no more than 100 hours, which is significantly different from Example 2, indicating that the PEO-Spiro modified with end groups in this invention can effectively increase the limiting current density of the polymer electrolyte membrane.

[0115] 7. Cycle performance testing of all-solid-state lithium metal batteries

[0116] Cycle performance tests were conducted on the all-solid-state lithium metal batteries prepared in Example 5 and Comparative Example 2 at 45°C and 0.2°C.

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

[0118] The above examples and comparative examples, based on the performance comparison before and after modification of the PEO end groups, demonstrate the effectiveness of the present invention in improving the electrical performance of PEO-based polymer electrolytes and the pioneering application of the fluorescence interface characterization method in the field of lithium batteries.

[0119] Based on the disclosure and teachings of the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. A polymer matrix possessing both excellent electrochemical performance and fluorescence properties, characterized in that, It is obtained by labeling fluorescent molecules on the end groups of polyethylene oxide. The method for preparing the fluorescent molecule includes the following steps: A-1) Tetrabromospirulin and 4-boronate-4',4'-dimethoxytriphenylamine in a mass ratio of 80-120:330-350 were added to an organic solvent and mixed thoroughly. The mixture was then placed in an inert gas atmosphere at a temperature ≥100℃ and reacted for at least 2 hours. After purification, an intermediate product was obtained. A-2) Under ambient temperature ≤0℃, boron tribromide was added dropwise to the intermediate product obtained in step A-1) until the color of the solution after the reaction did not change. Stirring was continued for at least 3 hours to ensure complete reaction. The mixture was then rinsed, dried, and the fluorescent molecule was obtained. The method for preparing the polymer matrix includes the following steps: B-1) Under ambient temperature ≤0℃, dissolve polyethylene oxide and pyridine in an organic solvent, add an appropriate amount of phosphorus tribromide and react for at least 30 min, then raise the temperature to ≥75℃ and continue the reaction for at least 10 h; B-2) After removing excess solvent, add fluorescent molecules and potassium hydroxide, and then place in an inert gas atmosphere at a temperature ≥60℃ to react fully for at least 10 hours; B-3) Neutralize the residual potassium hydroxide in the reaction solution, dialyze to remove most of the solvent, dry, and obtain the polymer matrix with excellent electrochemical and fluorescent properties.

2. The polymer matrix with both excellent electrochemical and fluorescent properties according to claim 1, 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.

3. The polymer matrix with both excellent electrochemical and fluorescent properties according to claim 1, characterized in that, In step B-2), the mass ratio of the polyethylene oxide to the fluorescent molecule is 100 to 150:

1.

4. A polymer electrolyte, characterized in that, It comprises the polymer matrix as described in any one of claims 1 to 3.

5. The polymer electrolyte according to claim 4, characterized in that, The preparation method of the polymer electrolyte includes the following steps: C-1) Under an inert gas atmosphere, the polymer matrix and lithium salt are prepared in a molar ratio of EO:Li+ = 12 to 16:1 and mixed and stirred in an organic solvent for at least 12 hours. C-2) The solution obtained in step C-1) is poured into a mold and then dried in a vacuum environment at 60-80°C for 12-24 hours to obtain the polymer electrolyte.

6. An all-solid-state battery, characterized in that, Includes solid electrolytes made from the polymer matrix as described in any one of claims 1 to 3.

7. The all-solid-state battery according to claim 6, characterized in that, The all-solid-state battery is an all-solid-state lithium metal battery, which includes the polymer electrolyte, positive electrode, and lithium negative electrode described above.

8. A non-destructive testing method applicable to all-solid-state batteries, characterized in that, The all-solid-state battery includes a solid electrolyte made of the polymer matrix as described in any one of claims 1 to 3; The all-solid-state battery was placed in the fluorescence mode of a microscope for imaging observation to check whether there were black gaps at the solid-solid interface, thereby determining the degree of bonding between the solid polymer electrolyte and the adjacent structural layers or the interface changes.

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