A high-sensitivity gas sensor applied to fire-fighting equipment of an electrochemical energy storage system

Abstract

The application relates to the field of electrochemical energy storage system fire-fighting equipment, and discloses a high-sensitivity gas sensor applied to electrochemical energy storage system fire-fighting equipment to solve the problems of poor sensitivity, low response value, inability to realize early safety warning and short service life of a sensor for monitoring lithium ion battery thermal runaway flammable gas in the prior art. x or Ti2CT x The gas sensor has good adsorption effect on the thermal runaway characteristic gas H2 of a lithium iron phosphate battery, and can realize high-response-value and high-sensitivity detection of hydrogen due to the high electrical conductivity, thereby realizing early safety warning of thermal runaway of the electrochemical energy storage system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fire-fighting equipment for electrochemical energy storage systems, and particularly relates to a high-sensitivity gas sensor applied to fire-fighting equipment for electrochemical energy storage systems. BACKGROUND

[0002] For energy storage systems using lithium ion batteries, the currently used safety warning system mainly refers to the temperature sensing and smoke sensing detection of building fire protection, and only when visible smoke or high temperature is detected, an alarm signal will be sent, which cannot realize the function of early safety warning. Lithium ion batteries will release flammable gas during thermal runaway, which provides a theoretical possibility for early warning through various types of gas sensors. Compared with voltage and temperature monitoring warning, gas detection warning technology can provide early warning, and gas detection has the advantages of simplicity and intuitiveness over other technical means. The combustible gas sensor is a converter that converts the volume fraction of a certain combustible gas into a corresponding electrical signal, and the sensing material is the key factor that determines the gas sensitivity of the gas sensor, which determines the response, selectivity and stability of the gas sensor.

[0003] The high sensitivity of the sensor must meet two requirements: low electrical noise caused by high conductivity and high signal caused by strong and rich analyte adsorption sites, but these two characteristics are a pair of contradictions, the introduction of adsorption sites (functional groups or defects) will cause the conductivity to decrease, and the existing sensor often cannot find a balance between these two contradictory conditions. Therefore, in order to realize the health status of lithium ion batteries based on gas sensors, it is necessary to combine the advantages of various materials, play a synergistic role, clarify the key mechanism of the microstructure and chemical group characteristics of different sensor materials for monitoring the target gas released by lithium ion battery thermal runaway, select appropriate materials and develop new materials, so that the sensitive characteristics of the gas sensor are optimized, and the miniaturization of the sensor device is realized.

[0004] For example, the patent document CN114577863A discloses a gallium oxide thin film hydrogen sensor, which comprises the following steps: cleaning and drying the conductive surface of the FTO glass substrate, pasting an insulating tape on the conductive surface of the dried FTO glass substrate, and covering the electrode with the insulating tape; ozone cleaning the FTO glass substrate; placing the ozone cleaned FTO glass substrate in a hydrothermal reaction solution containing gallium ions for hydrothermal reaction to grow a gallium oxide nanometer array film on the conductive surface of the FTO glass substrate; annealing the gallium oxide nanometer array film, then covering a mask on the surface of the gallium oxide nanometer array film to prepare a top electrode; then removing the insulating tape to expose the bottom electrode; and obtaining a hydrogen sensor attached with the gallium oxide nanometer array film layer. The sensor is an oxide sensor, which has high sensitivity to hydrogen at high temperature, and thus has weak ability for early safety warning. In addition, the sensor uses gallium oxide, which has high cost. SUMMARY

[0005] In order to overcome the problems of poor sensitivity, low response value, inability to realize early safety warning, and short service life of the sensor for monitoring the lithium ion battery thermal runaway combustible gas in the prior art, the application provides a high-sensitivity gas sensor applied to fire-fighting equipment of an electrochemical energy storage system, which has good adsorption effect on the thermal runaway characteristic gas H2 of the lithium iron phosphate battery, and has high electrical conductivity, so as to realize high response value and high sensitivity detection of hydrogen, and further realize early safety warning of thermal runaway of the electrochemical energy storage system.

[0006] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0007] A high-sensitivity gas sensor applied to fire-fighting equipment of an electrochemical energy storage system, wherein the gas sensor comprises a MXene film loaded with MOF material.

[0008] The application designs a new type of gas sensor material with long service life and high selectivity based on a two-dimensional layered structure material, which has the functions of confinement and adsorption system. The gas sensor material uses MXene as a support substrate, introduces a microporous MOF material with open metal sites by in-situ synthesis, and improves the response value and sensitivity of the MXene material to the thermal runaway characteristic gas H2 of the lithium iron phosphate battery.

[0009] Preferably, the MOF material is a nickel-based MOF material, and the MXene film is Ti3C2T x or Ti2CT x .

[0010] The nickel-based MOF material has good adsorption effect on H2, and the Ti3C2T xand Ti2CT x It possesses excellent electron transport rate, and its unique layered structure provides a good transport channel for electron charge. Ti3C2T x and Ti2CT x The surface is also rich in oxygen functional groups, which is beneficial for modification treatment to improve its sensitivity in detecting harmful gases, reduce its operating temperature, and improve its sensing efficiency.

[0011] Preferably, the MOF material is Ni-MOF-74, and the MXene film is Ti3C2T. x .

[0012] Ni-MOF-74 exhibits excellent physical adsorption properties for H2, a characteristic gas of thermal runaway in lithium iron phosphate batteries.

[0013] Preferably, the MXene film loaded with MOF material is prepared by a method comprising the following steps:

[0014] (1) Dissolve LiF in hydrochloric acid solution, then add Ti3AlC2 or Ti2AlC, heat and stir to react, and then separate to obtain the precipitate;

[0015] (2) The precipitate was dispersed in water, ultrasonically treated, the suspension was centrifuged, and the supernatant was freeze-dried under vacuum to obtain MXene film powder;

[0016] (3) Disperse MXene film powder in solvent, add organic ligand and nickel salt in sequence, heat and react, separate and collect solids, immerse the solids in N,N-dimethylformamide and methanol in sequence, and then heat and dry under vacuum to obtain Ni-MOF / MXene film.

[0017] Hydrofluoric acid etching of Ti3AlC2 or Ti2AlC yields Ti3C2T x or Ti2CT x Then Ti3C2T x or Ti2CT x Ultrasonic treatment and freeze-drying were performed to improve and maintain its two-dimensional layered structure, and finally Ti3C2T was added. x or Ti2CT x Ni-MOF / MXene films were obtained by in-situ synthesis of nickel-based MOF materials.

[0018] Preferably, in step (1), the concentration of the hydrochloric acid solution is 8~9 mol / L, and the molar ratio of LiF, HCl and Ti3AlC2 or Ti2AlC is (0.25~0.3):1:(0.025~0.03).

[0019] As preferred, the temperature of the heated stirring reaction in step (1) is 35-40℃, and the reaction time is 36-48h.

[0020] As preferred, in step (3), the MXene film powder is dispersed in a solvent, and then organic ligand and nickel salt are added in sequence, and the mixture is heated to 90-100℃ and reacted for 12-48h, and then the solid is collected, and then the solid is sequentially immersed in N,N-dimethylformamide and methanol, and then the N,N-dimethylformamide and methanol are removed to obtain the Ni-MOF / MXene film.

[0021] With the increase of reaction time after the addition of organic ligand and nickel salt, the loading amount of nickel-based MOF on the MXene material increases, and the adsorption capacity of the Ni-MOF / MXene film for H2 also increases, but when the reaction time is too long, the nickel-based MOF material grown on the surface will gradually accumulate together to form a dense layer, which will hinder the charge transfer between Ni-MOF and MXene, so the reaction time is preferably 12-48h.

[0022] As more preferred, in step (3), the MXene film powder is dispersed in a solvent, and then organic ligand and nickel salt are added in sequence, and the mixture is heated to 90-100℃ and reacted for 24-48h.

[0023] As preferred, in step (3), the organic ligand is terephthalic acid, a mono-substituted terephthalic acid or a di-substituted terephthalic acid, and the nickel salt is nickel acetate, nickel chloride, nickel nitrate or nickel sulfate.

[0024] As more preferred, in step (3), the organic ligand is 2,5-dihydroxyterephthalic acid.

[0025] As preferred, in step (3), the molar ratio of the organic ligand to nickel ions in the nickel salt is (1-1.2):1.

[0026] As preferred, in step (3), the solvent is a mixed solution of N,N-dimethylformamide, ethanol and water, and the volume ratio of N,N-dimethylformamide, ethanol and water is (15-20):1:1.

[0027] Therefore, the present application has the following beneficial effects: (1) the MOF material with excellent physical adsorption performance for H2 is introduced into the MXene two-dimensional layered structure material through an in-situ synthesis strategy, the response value and sensitivity of the MXene material for H2 are improved, and a self-supporting MXene film loaded with the MOF material is obtained; (2) the MXene film loaded with the MOF material has excellent adsorption and sensing performance for H2, the gas sensor using the film has high sensitivity and fast response speed for H2 detection, and can be used as early warning in lithium ion battery fire-fighting equipment, and early warning of thermal runaway of a lithium ion battery energy storage system is realized. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 XRD patterns of Ti3C3T x and Ni-MOF-74 / Ti3C3T x of Example 1.

[0029] Figure 2 SEM images of Ti3C3T x and Ni-MOF-74 / Ti3C3T x of Example 1, wherein the left side is Ti3C3T x and the right side is Ni-MOF-74 / Ti3C3T x .

[0030] Figure 3 Response values of the film sensors prepared in Comparative Example and Examples 1-4 for H2. DETAILED DESCRIPTION

[0031] The present application will be further described below in combination with the drawings and specific implementation methods.

[0032] Example 1

[0033] A gas sensor comprising a MXene film loaded with a MOF material is prepared by the following steps:

[0034] (1) Preparation of Ti3C3T x powder

[0035] (1.1) 2 g of LiF was dissolved in 30 mL of 9 mol / L HCl, then 1.4 g of Ti3AlC2 powder was added to the above mixed solution, and the mixed solution was kept at 35℃ for 48 h under magnetic stirring, and then the mixed solution was centrifuged at 10000 rpm for 30 min to obtain a precipitate;

[0036] (1.2) The precipitate was washed with deionized water until the pH value of the washing liquid was higher than 6, and the washed precipitate was re-dispersed in 100 mL of distilled water, and was ultrasonically treated for 1 h to further delaminate, and then the suspension was centrifuged at 3500 rpm for 1 h, and the supernatant was collected and stored, and the supernatant was freeze-dried under vacuum to obtain the multilayer Ti3C3T x powder;

[0037] (2) Ni-MOF-74 / Ti3C3T x Preparation of thin film

[0038] (2.1) 1 g of Ti3C3T prepared in step (1) was taken and added into 100 mL of mixed solvent obtained by mixing N,N-dimethylformamide, anhydrous ethanol and deionized water in a volume ratio of 15:1:1, and the Ti3C3T x powder was ultrasonically treated for 2 h to completely disperse the Ti3C3T x powder; x dispersion;

[0039] (2.2) 0.560 g of dihydroxyterephthalic acid was added into the Ti3C3T x dispersion, and was ultrasonically treated for 15 min to completely dissolve it, and then 0.358 g of nickel nitrate hexahydrate was added, and was stirred at room temperature to completely dissolve it, and the above mixture was added into a stainless steel reaction kettle of polytetrafluoroethylene, and was reacted at 100°C for 12 h, and after the reaction was completed, the reaction kettle was placed at room temperature to naturally cool, and the mixture was collected by centrifugation, and the obtained solid was immersed in 50 mL of N,N-dimethylformamide for 24 h, and the solvent was replaced every 12 h, and then the solid was immersed in 50 mL of methanol, and was introduced into an 80 mm peel-off culture dish, and was dried at room temperature for 48 h, and was transferred to a vacuum at 300°C for 3 h to obtain Ni-MOF-74 / Ti3C3T x thin film;

[0040] (3) Preparation of gas sensor

[0041] The Ni-MOF-74 / Ti3C3T x thin film prepared in step (2) was assembled into a gas sensor, and the gas sensing detection instrument used for testing was a CGS-8 gas sensitive analysis system (Ailite Technologies Co., Ltd.). First, the thin film to be tested was cut into a size of 1x1 cm, and then the thin film was adhered to a six-legged sensor using conductive silver adhesive to assemble a test sensor for testing.

[0042] Example 2

[0043] A gas sensor comprising a MXene film loaded with MOF material, the preparation steps of which differ from those of Example 1 in that in step (2.2) the mixed solution is added to a stainless steel reaction kettle with a polytetrafluoroethylene inner wall, and the reaction is carried out at 100°C for 24h.

[0044] Example 3

[0045] A gas sensor comprising a MXene film loaded with MOF material, the preparation steps of which differ from those of Example 1 in that in step (2.2) the mixed solution is added to a stainless steel reaction kettle with a polytetrafluoroethylene inner wall, and the reaction is carried out at 100°C for 36h.

[0046] Example 4

[0047] A gas sensor comprising a MXene film loaded with MOF material, the preparation steps of which differ from those of Example 1 in that in step (2.2) the mixed solution is added to a stainless steel reaction kettle with a polytetrafluoroethylene inner wall, and the reaction is carried out at 100°C for 48h.

[0048] Comparative Example 1

[0049] A gas sensor comprising a MXene film, prepared by the following steps:

[0050] (1) Ti3C3T x Preparation of powder

[0051] (1.1) 2 g of LiF was dissolved in 30 mL of 9 mol / L HCl, then 1.4 g of Ti3AlC2 powder was added to the above mixed solution, and the mixed solution was kept at 35°C for 48 h under magnetic stirring, then the mixed solution was centrifuged at 10000 rpm for 30 min to obtain the precipitate;

[0052] (1.2) The precipitate was washed with deionized water until the pH value of the washing liquid was higher than 6, the washed precipitate was re-dispersed in 100 mL of distilled water, and ultrasonic treatment was carried out for 1 h to further delaminate, then the suspension was centrifuged at 3500 rpm for 1 h, the supernatant was collected and stored, and the supernatant was freeze-dried under vacuum to obtain the multilayer Ti3C3T x powder;

[0053] (2) Ti3C3T x Preparation of film

[0054] (2.1) 1 g of Ti3C3T x powder prepared in step (1) was added to 100 mL of mixed solvent obtained by mixing N,N-dimethylformamide, anhydrous ethanol and deionized water in a volume ratio of 15:1:1, and ultrasonic treatment was carried out for 2 h to delaminate the Ti3C3Tx The powder was completely dispersed to obtain Ti3C3T x dispersion liquid;

[0055] (2.2) The dispersion liquid was centrifuged to collect the solid, the obtained solid was immersed in 50 mL of methanol, introduced into an 80 mm exfoliation culture dish, dried at room temperature for 48 h, and transferred to a vacuum dryer at 300 ℃ for 3 h to obtain Ti3C3T x thin film;

[0056] (3) The Ti3C3T prepared in step (2) was mixed with 0.5 g of ZIF-8 to obtain a mixture, and the mixture was placed in a stainless steel autoclave with a polytetrafluoroethylene inner wall, and reacted at 100 ℃ for 60 h to obtain a ZIF-8 / Ti3C3T x The thin film was assembled into a gas sensor, and the gas sensor detection instrument used for testing was a CGS-8 gas sensitive analysis system (Ailite Technologies Co., Ltd.). First, the thin film to be tested was cut into a size of 1 × 1 cm, and then the thin film was adhered to a six-legged sensor using conductive silver glue to assemble a test sensor for testing.

[0057] Comparative Example 2

[0058] A gas sensor including a MXene thin film, the preparation steps of which are different from those of Example 1, wherein in step (2.2), the mixed solution is added to a stainless steel reaction kettle with a polytetrafluoroethylene inner wall, and reacted at 100 ℃ for 60 h.

[0059] Comparative Example 3

[0060] A gas sensor including a MXene and ZIF-8 thin film, prepared by the following steps:

[0061] (1) Ti3C3T x Preparation of powder

[0062] (1.1) 2 g of LiF was dissolved in 30 mL of 9 mol / L HCl, then 1.4 g of Ti3AlC2 powder was added to the above mixed solution, and stirred under magnetic stirring at 35 ℃ for 48 h, then the mixed solution was centrifuged at 10000 rpm for 30 min to obtain a precipitate;

[0063] (1.2) The precipitate was washed with deionized water until the pH value of the washing liquid was higher than 6, and the washed precipitate was re-dispersed in 100 mL of distilled water, and ultrasonic treated for 1 h to further delaminate, then the suspension was centrifuged at 3500 rpm for 1 h, the supernatant was collected and stored, and the supernatant was freeze-dried under vacuum to obtain a multi-layer Ti3C3T x powder;

[0064] (2) ZIF-8 / Ti3C3T x Preparation of thin film

[0065] (2.1) Take 1g of Ti3C3T obtained in step (1) x The powder was added to 100 mL of a mixed solvent obtained by mixing N,N-dimethylformamide, anhydrous ethanol, and deionized water in a volume ratio of 15:1:1, and the mixture was sonicated for 2 hours to allow Ti3C3T to precipitate. x The powder was completely dispersed to obtain Ti3C3T x Dispersion;

[0066] (2.2) Take 0.649 g of terephthalic acid and add it to Ti3C3T x After the dispersion was completely dissolved by sonication for 15 minutes, 0.293 g of zinc nitrate hexahydrate was added and stirred at room temperature until completely dissolved. The mixture was then added to a stainless steel reactor lined with polytetrafluoroethylene and reacted at 100°C for 12 hours. After the reaction was complete, the reactor was allowed to cool naturally at room temperature. The solid in the mixture was collected by centrifugation. The obtained solid was immersed in 50 mL of N,N-dimethylformamide for 24 hours, with the solvent changed every 12 hours. The solid was then immersed in 50 mL of methanol and transferred to an 80 mm peeling culture dish. It was dried at room temperature for 48 hours and then transferred to a vacuum environment at 300°C for 3 hours to obtain ZIF-8 / Ti3C3T. x film;

[0067] (3) Fabrication of gas sensors

[0068] The ZIF-8 / Ti3C3T obtained in step (2) x The thin film was assembled into a gas sensor, and the gas sensing instrument used for testing was the CGS-8 gas-sensitive analysis system (Elite Technologies Co., Ltd.). First, the thin film to be tested was cut into 1×1 cm pieces, and then conductive silver paste was used to attach the fiber film to the six-pin sensor to assemble the test sensor for testing.

[0069] The Ti3C3T obtained in step (1) of Example 1 x Powder and Ni-MOF-74 / Ti3C3T obtained in step (2) x The thin film was scanned by XRD and SEM, respectively. The obtained XRD patterns are shown below. Figure 1 As shown, 7 o The peaks in the appendix are typical of Ti3C3T. x Characteristic peaks indicate that the Ti3C3T obtained in step (1) x The crystal structure is extremely small; while Ti3C3T x After loading Ni-MOF-74, Ti3C3T was retained. x Characteristic peaks were observed, and characteristic peaks belonging to Ni-MOF-74 were also present, indicating that the loading of Ni-MOF-74 did not affect Ti3C3T. xThe material itself structure causes the influence, Ni-MOF-74 is successfully loaded in Ti3C3T x The SEM scanning obtained figure is as shown in the figure Figure 2 , the left side is Ti3C3T x , the sheet layer structure of Ti3C3T x Can be seen, the surface presents a kind of fibrous network structure, can constitute continuous signal transmission route, the right side is Ni-MOF-74 / Ti3C3T x Film, the sheet layer structure of Ti3C3T x Can be seen, the surface of the sheet layer structure is loaded with a lot of particles, and the particles are in-situ loaded Ni-MOF-74.The above two figures show that the Ni-MOF-74 / Ti3C3T x Film of embodiment 1 successfully in-situ loads Ni-MOF-74 in the sheet layer structure of Ti3C3T x .

[0070] The Ni-MOF-74 / Ti3C3T x Film prepared by different loading time of embodiment 1-4 and Ti3C3T x Film prepared by comparative example 1-3 are respectively assembled into gas sensors, and the performance of the sensor is tested using CGS-8 gas sensitive analysis system, and the detection temperature is 25 DEG C.The sensor response performance of the sensor to H2 is measured by diluting H2 standard gas to 10 ppm, and the response value of the sensor after 1s of H2 release is recorded.

[0071] As shown in the figure Figure 3 , the response value of the gas sensor prepared by Ni-MOF-74 / Ti3C3T x Film is high when the synthesis time of Ni-MOF-74 is 24-48h, which shows that the application is sensitive and fast to H2, and can be used for early warning of thermal runaway of lithium ion battery energy storage system.The response value of the gas sensor prepared by Ti3C3T x Film without loading Ni-MOF-74 to H2 is low, and is 1.5%, along with the increase of the synthesis time of Ni-MOF-74 in Ti3C3T x , the loading amount of Ni-MOF-74 increases, because Ni-MOF-74 has excellent adsorption performance to H2, the response value of Ni-MOF-74 / Ti3C3T x Film to H2 increases.When the reaction time is 36h, the response value of Ni-MOF-74 / Ti3C3T xThe response of the thin film sensor to H2 increased to 11.2%, reaching the highest response value. However, when the reaction time was too long, Ni-MOF-74 gradually accumulated together to form a relatively dense layer after the surface was saturated, which limited the charge transfer between the composite materials. And when the loading reached a certain degree, the Ti3C3T x Ni-MOF-74 continued to be generated on the surface, which made the response of the Ni-MOF-74 / Ti3C3T x The response of the thin film sensor to H2 decreased. This resulted in the response of the gas sensor to H2 being lower than 36h when the reaction time was 48h. In the comparative example 2, the synthesis time was 60h, and the response of the gas sensor prepared under the same detection conditions was only 2.1%, which was not significantly improved compared with the response of the comparative example 1.

[0072] In the comparative example 3, the Ti3C3T x The loading on the film was ZIF-8 material, and the response value was 1.5%, which indicated that the adsorption speed and amount of Ni-MOF-74 to hydrogen were higher than those of ZIF-8 material.

Claims

1. A high sensitive gas sensor applied to fire fighting equipment of electrochemical energy storage system, characterized in that, The gas sensor comprises a MXene film loaded with a MOF material; the detection object of the gas sensor is H2; the MOF material is Ni-MOF-74; the MXene film is Ti3C2T x .

2. A high sensitive gas sensor applied to fire-fighting equipment of electrochemical energy storage system according to claim 1, characterized in that, The MOF material loaded MXene film is prepared by a method comprising the following steps: (1) dissolving LiF in a hydrochloric acid solution, then adding Ti3AlC2, and separating the precipitate after heating and stirring reaction; (2) dispersing the precipitate into water, treating with ultrasonic, centrifuging the suspension, and freeze-drying the supernatant under vacuum to obtain a MXene film powder; (3) dispersing the MXene film powder into a solvent, sequentially adding an organic ligand and a nickel salt, collecting the solid after heating reaction, then immersing the solid into N,N-dimethylformamide and methanol, and removing N,N-dimethylformamide and methanol to obtain a Ni-MOF / MXene film.

3. A high sensitive gas sensor applied to fire-fighting equipment of electrochemical energy storage system according to claim 2, characterized in that, In step (1), the concentration of the hydrochloric acid solution is 8-9 mol / L, and the molar ratio of LiF, HCl and Ti3AlC2 is (0.25-0.3):1:(0.025-0.03).

4. A high sensitive gas sensor applied to fire-fighting equipment of electrochemical energy storage system according to claim 2 or 3, characterized in that, In step (1), the heating and stirring reaction is carried out at a temperature of 35-40℃ for 36-48 h.

5. A high sensitive gas sensor applied to fire fighting equipment of electrochemical energy storage system according to claim 2, characterized in that, In step (3), the MXene film powder is dispersed into a solvent, an organic ligand and a nickel salt are sequentially added, and the reaction is carried out at 90-100℃ for 12-48 h, then the solid is collected, the solid is sequentially immersed into N,N-dimethylformamide and methanol, and the solid is dried at 300-350℃ under vacuum for 3-4 h to obtain the Ni-MOF / MXene film.

6. A high sensitive gas sensor applied to fire fighting equipment of electrochemical energy storage system according to claim 2, characterized in that, In step (3), the organic ligand is terephthalic acid, a mono-substituted terephthalic acid or a di-substituted terephthalic acid.

7. A high sensitive gas sensor applied to fire fighting equipment of electrochemical energy storage system according to claim 2, characterized in that, In step (3), the nickel salt is nickel acetate, nickel chloride, nickel nitrate or nickel sulfate.

8. A high sensitive gas sensor applied to fire fighting equipment of electrochemical energy storage system according to claim 2 or 6 or 7, characterized in that, In step (3), the molar ratio of the organic ligand to nickel ions in the nickel salt is (1-1.2):

1.

9. A high sensitive gas sensor applied to fire fighting equipment of electrochemical energy storage system according to claim 2, characterized in that, In step (3), the solvent is a mixed solution of N,N-dimethylformamide, ethanol and water, and the volume ratio of N,N-dimethylformamide, ethanol and water is (15-20):1:1.

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