A method for evaluating the uniformity of adhesive solution

Abstract

The present application proposes a method for evaluating the uniformity of a glue solution, comprising: preparing a glue solution comprising a binder and a first organic solvent in a preset ratio; taking the glue solution at different locations at the same time, or / and the glue solution at the same location at different times, or / and the glue solution at different locations at different times as test samples; ultrasonically extracting and centrifuging the test samples, filtering the supernatant to obtain a mixed solution; testing the mixed solution using a gas chromatography-mass spectrometer to obtain a peak area of ​​the first organic solvent; and determining the uniformity of the glue solution based on the degree of similarity between the peak areas of the first organic solvent of each test sample. The glue solution uniformity evaluation method described in the present application helps improve the accuracy of glue solution uniformity testing and can significantly shorten testing time. Furthermore, no components are volatilized, and there is no environmental pollution.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion battery material testing, and in particular to a method for evaluating the uniformity of a glue solution. Background Art

[0002] Adhesives are substances that connect homogeneous or heterogeneous materials through surface bonding. They offer advantages such as consistent stress distribution and lightweight properties, making them widely used in many industries. In some areas, the bonding properties of adhesives significantly impact product performance, such as in lithium-ion batteries.

[0003] In recent years, lithium-ion batteries have gained widespread application in the secondary battery field due to their high energy density, long lifespan, and environmental friendliness. The main components of a lithium-ion battery include a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode is composed of an active material, a conductive agent, and a binder. The binder acts as a composite material, bonding the active material particles and conductive agent particles together. The binder used in the positive electrode of a lithium-ion battery is PVDF. To ensure uniform mixing of PVDF, it must first be prepared into a glue solution. The uniformity of this glue solution has a significant impact on electrode performance.

[0004] Taking PVDF / NMP glue as an example, there are currently several methods for measuring the uniformity of the glue:

[0005] 1. Drying and Weighing Method: PVDF and NMP in PVDF / NMP adhesive have different volatility. When the PVDF / NMP adhesive is heated, NMP evaporates first, leaving behind the PVDF solids. Based on the change in mass of the PVDF / NMP adhesive, the solid content of the substance being tested can be calculated. The method involves weighing and peeling a piece of foil. Then, 1-5g of PVDF / NMP adhesive is evenly applied to the foil. The foil is then baked in a forced-air oven at 100-120°C for 2-3 hours. After baking, the solid content is calculated by weighing the foil. The difference in solid content is used to determine the uniformity of the PVDF / NMP adhesive. However, this method is environmentally friendly and time-consuming.

[0006] 2. Viscosity test method: The viscosity of the upper, middle, and lower layers of the PVDF / NMP adhesive is measured using a viscometer, and after different periods of standing. The uniformity of the PVDF / NMP adhesive is determined by the change in viscosity. However, this method is limited by the fact that changes in the viscosity of the PVDF / NMP adhesive require changes in the rotor and / or speed used. This can lead to differences in the measured data, as changes in the viscometer rotor and / or speed also cause variations in temperature. Furthermore, viscosity also changes with temperature, making it difficult to maintain consistent temperatures inside and outside the adhesive. This can result in significant errors.

[0007] Therefore, it is necessary to conduct further research and development on the evaluation of glue uniformity. Summary of the Invention

[0008] In view of this, the present application aims to provide a method for evaluating the uniformity of glue liquid, which helps to improve the accuracy of glue liquid uniformity testing and can greatly shorten the testing time. At the same time, it does not require the use of an oven, there is no component volatilization, and it does not pollute the environment.

[0009] To achieve the above objectives, the present invention provides a method for evaluating the uniformity of a glue solution, comprising:

[0010] preparing a glue solution comprising a binder and a first organic solvent in a preset ratio;

[0011] Taking the glue solution at different positions at the same time or / and the glue solution at the same position at different times or / and the glue solution at different positions at different times as test samples;

[0012] After ultrasonic extraction and centrifugal separation of the test sample, the supernatant is filtered to obtain a mixed solution;

[0013] Detecting the mixed solution using a gas chromatography-mass spectrometer to obtain a peak area of ​​the first organic solvent;

[0014] The uniformity of the glue solution is determined based on the closeness of the peak areas of the first organic solvent of each test sample.

[0015] In some embodiments, the binder includes at least one of polyvinylidene fluoride, polyacrylonitrile, and polyamide, and the first organic solvent includes at least one of N-methylpyrrolidone, dimethylacetamide, dimethylformamide, and dimethyl sulfoxide.

[0016] In some embodiments, the method for judging the uniformity of the glue solution is: the closer the peak areas of the first organic solvent of each test sample are, the better the uniformity of the glue solution.

[0017] In some embodiments, judging the uniformity of the glue solution according to the closeness of the peak areas of the first organic solvent of each of the test samples comprises:

[0018] Obtaining the relative standard deviation of the peak area of ​​the first organic solvent of each test sample;

[0019] If the relative standard deviation is below a preset value, it is judged that the uniformity of the glue solution is good;

[0020] If the relative standard deviation is greater than the preset value, it is determined that the glue solution has poor uniformity.

[0021] In some embodiments, the preset value is 0.2-0.5%.

[0022] In some embodiments, the preset ratio of the binder to the first organic solvent is a preset mass ratio, and the preset mass ratio is (1-9): (99-91).

[0023] In some embodiments, the method of ultrasonically extracting the test sample comprises: mixing the test sample with a second organic solvent, and then ultrasonically extracting the sample under conditions of 30-50 kHz and 200-300 W for 3-8 minutes.

[0024] In some embodiments, the centrifugal separation time is 3-8 minutes, and the centrifugal separation speed is 8000-12000 rpm.

[0025] In some embodiments, the filter membrane used for the filtration is an oil-based filter membrane.

[0026] In some embodiments, the test sample and the second organic solvent are mixed in an amount of 5-50 ml of the second organic solvent per 500.0-1000.0 mg of the test sample.

[0027] In some embodiments, the second organic solvent is at least one of methanol, dichloromethane, and n-hexane with a chromatographic purity of 99.9% or higher.

[0028] In some embodiments, the mixed solution is detected using a SIM / SACN hybrid mode in the gas chromatography-mass spectrometry.

[0029] In some embodiments, the gas chromatography measurement conditions in the gas chromatography-mass spectrometry instrument include: the chromatographic column is Rtx-MS, the chromatographic column length is 30m, the chromatographic column inner diameter is 0.25mm, the chromatographic column film thickness is 0.25μm, the carrier gas is helium, and the helium purity is 99.999%; the injection volume is 1μL, the split ratio is 20-30:1; the number of solvent flushes before injection is 3-5 times; the number of solvent flushes after injection is 3-5 times; the number of sample flushes is 2-3 times; the injection port temperature is 230-250℃; the heating program is: initial temperature 90-100℃, maintain 3-5min, then heat up to 120-150℃ at a heating rate of 5-10℃ / min, and then heat up to 220-250℃ at a heating rate of 5-10℃ / min.

[0030] In some embodiments, the step of preparing the glue solution is performed under stirring conditions, the stirring time is 200-280 min, and the stirring speed is 500-700 rpm.

[0031] In some embodiments, the method for evaluating the uniformity of the glue solution further includes the step of diluting the mixed solution with a third organic solvent before using a gas chromatography-mass spectrometer to detect the mixed solution.

[0032] In some embodiments, the third organic solvent is at least one of methanol, dichloromethane, and n-hexane with a chromatographic purity of 99.9% or higher.

[0033] In some embodiments, the dilution factor is 50-200 times.

[0034] The glue uniformity evaluation method of the embodiment of the present application can bring the following beneficial effects: it helps to improve the accuracy of the glue uniformity test and can greatly shorten the test time. At the same time, it does not require the use of an oven, there is no component volatilization, and it does not pollute the environment.

[0035] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0037] Figure 1 This is a flow chart of a method for evaluating glue uniformity according to an exemplary embodiment of the present application.

[0038] Figure 2 This is a flow chart of a method for evaluating glue uniformity according to another exemplary embodiment of the present application.

[0039] Figure 3 This is a flow chart of a method for evaluating glue uniformity according to another exemplary embodiment of the present application.

[0040] Figure 4 This is a flow chart of a method for evaluating glue uniformity according to another exemplary embodiment of the present application.

[0041] Figure 5 This is a flow chart of a method for evaluating glue uniformity according to another exemplary embodiment of the present application.

[0042] Figure 6 This is a flow chart of a method for evaluating glue uniformity according to another exemplary embodiment of the present application.

[0043] Figure 7 This is a flow chart of a method for evaluating glue uniformity according to another exemplary embodiment of the present application. DETAILED DESCRIPTION

[0044] The embodiments of the present application are described in detail below. The embodiments are exemplary and intended to be used to explain the present application, but should not be understood as limiting the present application.

[0045] Throughout this application, the disclosure of numerical ranges includes disclosure of all values ​​within the entire range and further subdivided ranges, including endpoints and subranges given within those ranges.

[0046] In the application, the raw materials, equipment, etc. involved, unless otherwise specified, are all raw materials and equipment that can be produced through commercial channels or known methods; the methods involved, unless otherwise specified, are all conventional methods.

[0047] Figure 1 Flowchart of a method for evaluating the uniformity of a glue solution according to an exemplary embodiment of the present application. Figure 1 As shown, the evaluation method includes the following steps:

[0048] S101 , preparing a glue solution comprising a binder and a first organic solvent in a preset ratio.

[0049] As a non-limiting example, the glue solution consists of only a binder and a first organic solvent.

[0050] In some embodiments, the binder includes, but is not limited to, at least one of polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyamide (PA), etc., and the first organic solvent includes, but is not limited to, at least one of N-methylpyrrolidone (NMP), dimethylacetamide (DMA), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), etc. As one possible example, the glue solution is composed of the binder and the first organic solvent, the binder is polyvinylidene fluoride (PVDF), and the first organic solvent is N-methylpyrrolidone (NMP).

[0051] In some embodiments, the preset ratio of the binder and the first organic solvent is a preset mass ratio, which is (1-9): (99-91), including but not limited to 1:99, 3:97, 5:95, 7:93, 9:91, etc. When the preset mass ratio of the binder and the first organic solvent is within the above range, the viscosity of the slurry can be better controlled so that the slurry can be evenly coated on the electrode. If the preset mass ratio of the binder and the first organic solvent is lower than 1:99, the viscosity of the configured slurry is too low, which makes the storage performance worse and prone to sedimentation, and the dispersibility is also relatively general; at the same time, if the viscosity of the slurry is too low, it will also cause difficulties in coating and drying, resulting in wet sheets, as well as problems such as cracking of the coating, agglomeration of slurry particles, and poor surface density consistency. If the preset mass ratio of the binder and the first organic solvent is higher than 9:91, the configured slurry has poor fluidity, poor leveling performance and wetting effect on copper foil and aluminum foil, which is not conducive to the coating process and is prone to abnormal appearance of the electrode.

[0052] In some embodiments, to uniformly mix the binder and the first organic solvent, the binder and the first organic solvent are stirred in a predetermined mass ratio to form a binder-first organic solvent glue solution, wherein the stirring time is 200-280 minutes and the stirring speed is 500-700 rpm. As non-limiting examples, the stirring time includes but is not limited to 200 minutes, 220 minutes, 240 minutes, 260 minutes, or 280 minutes, and the stirring speed includes but is not limited to 500 rpm, 550 rpm, 600 rpm, 650 rpm, or 700 rpm.

[0053] S102. Take the glue at different positions at the same time as test samples.

[0054] In the present application, taking glue at different positions at the same time refers to a glue fixed at a preset ratio (such as a preset mass ratio) of a binder and a first organic solvent, sampling at different positions thereof at the same time, and the glue samples obtained at each sampling position. Different positions refer to different sampling positions of the same glue at the same time. In some embodiments, the number of different positions is more than 3, and the more the number, the more accurate the test, but the more complicated the process. Weighing accuracy and ease of operation, the number of different positions is generally 3-10, including but not limited to 3, 4, 5, 6, 7, 8, 9 or 10. As a non-limiting example, different positions can be positions such as 1 cm, 3 cm, 5 cm, 7 cm, 9 cm from the upper surface of the glue.

[0055] S103. Ultrasonic extraction and centrifugal separation of the test sample are performed, and the supernatant is filtered to obtain a mixed solution.

[0056] In some embodiments, the method of ultrasonically extracting the test sample comprises: mixing the test sample with a second organic solvent, followed by ultrasonic extraction for 3-8 minutes at 30-50 kHz and 200-300 W. As non-limiting examples, the frequency of ultrasonic extraction includes, but is not limited to, 30 kHz, 35 kHz, 40 kHz, 45 kHz, 50 kHz, etc.; the power of ultrasonic extraction includes, but is not limited to, 200 W, 225 W, 250 W, 275 W, or 300 W, etc.; and the ultrasonic extraction time includes, but is not limited to, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, or 8 minutes, etc.

[0057] In some embodiments, the centrifugal separation time is 3-8 min, including but not limited to 3 min, 4 min, 5 min, 6 min, 7 min or 8 min.

[0058] In some embodiments, the rotation speed of centrifugal separation is 8000-12000 rpm, including but not limited to 8000 rpm, 9000 rpm, 10000 rpm, 11000 rpm or 12000 rpm.

[0059] In some embodiments, the filter membrane used for filtration is an oil filter membrane. As a possible example, the filter membrane used for filtration is a 0.22 μm oil filter membrane.

[0060] In some embodiments, the test sample and the second organic solvent are mixed in an amount of 5-50 ml of the second organic solvent per 500.0-1000.0 mg of the test sample.

[0061] In some embodiments, the second organic solvent is at least one of methanol, dichloromethane, and n-hexane with a chromatographic purity of 99.9% or higher.

[0062] S104: Detecting the mixed solution using a gas chromatography-mass spectrometer to obtain a peak area of ​​the first organic solvent.

[0063] In some embodiments, the present application's method for evaluating the uniformity of the glue solution further includes a step of diluting the mixed solution with a third organic solvent before using a gas chromatography-mass spectrometer (GCMS) to detect the mixed solution. Wherein, the third organic solvent is at least one of methanol, dichloromethane, and n-hexane with a chromatographic purity of more than 99.9%, and the dilution factor is 50-200 times. As a possible example, before using a gas chromatography-mass spectrometer (GCMS) to detect the mixed solution, 10 μl of the mixed solution can be diluted 100 times with the third organic solvent, and then the diluted mixed solution can be detected using a gas chromatography-mass spectrometer. It should be noted that the third organic solvent and the second organic solvent in the present application can be the same or different.

[0064] In some embodiments, the mixed solution is detected using a SIM / SACN hybrid mode in a gas chromatography-mass spectrometer.

[0065] In some embodiments, the gas chromatography measurement conditions in the gas chromatography-mass spectrometry instrument include: the chromatographic column is Rtx-MS, the chromatographic column length is 30m, the chromatographic column inner diameter is 0.25mm, the chromatographic column film thickness is 0.25μm, the carrier gas is helium, and the helium purity is 99.999%; the injection volume is 1μL, the split ratio is 20-30:1; the number of solvent rinses before injection is 3-5 times; the number of solvent rinses after injection is 3-5 times; the number of sample rinses is 2-3 times; the injection port temperature is 230-250℃; the heating program is: initial temperature 90-100℃, maintain 3-5min, then heat up to 120-150℃ at a heating rate of 5-10℃ / min, and then heat up to 220-250℃ at a heating rate of 5-10℃ / min.

[0066] S105 , judging the uniformity of the glue solution according to the degree of similarity of the peak areas of the first organic solvent of each test sample.

[0067] In some embodiments, the method for judging the uniformity of the glue solution is: the closer the peak areas of the first organic solvent of each test sample are, the better the uniformity of the glue solution.

[0068] In some embodiments, judging the uniformity of the glue solution based on the closeness of the peak areas of the first organic solvent of each test sample comprises the following steps:

[0069] (1) obtaining the relative standard deviation of the peak area of ​​the first organic solvent of each test sample;

[0070] (2) If the relative standard deviation is below the preset value, the uniformity of the glue solution is good; if the relative standard deviation is greater than the preset value, the uniformity of the glue solution is poor.

[0071] The preset value in step (2) can be determined based on the uniformity requirements of the glue solution. Generally, the smaller the preset value, the higher the required uniformity of the glue solution. Correspondingly, the smaller the relative standard deviation, the better the uniformity of the glue solution. As a non-limiting example, the preset value is 0.2-0.5%, including but not limited to 0.2%, 0.3%, 0.4% or 0.5%.

[0072] Figure 2 FIG. 1 is a flow chart of another exemplary embodiment of a method for evaluating the uniformity of a glue solution according to the present application. Figure 2 As shown, the evaluation method includes the following steps:

[0073] S201 , preparing a glue solution comprising a binder and a first organic solvent in a preset ratio.

[0074] S202. Take the glue solution at the same position at different times as test samples.

[0075] In this application, the glue at the same position at different times refers to a glue fixed with a preset ratio (ratio preset mass ratio) of a binder and a first organic solvent, and samples are taken at different times at the same position of the glue, and the glue samples obtained at each sampling time. Different times refer to different sampling times of the same glue at the same position. In certain embodiments, the number of different times is more than 3, and the more the number, the better it can reflect the long-term uniformity of the glue, but the process is also more complicated. Weighing the long-term uniformity effect and the ease of operation, the number of different times is generally 3-10, including but not limited to 3, 4, 5, 6, 7, 8, 9 or 10. As a non-limiting example, different times can be 0h, 2h, 4h, 6h, 8h etc.

[0076] S203. Ultrasonic extraction and centrifugal separation of the test sample are performed, and the supernatant is filtered to obtain a mixed solution.

[0077] S204: Detecting the mixed solution using a gas chromatography-mass spectrometer to obtain a peak area of ​​the first organic solvent.

[0078] S205 . Determine the uniformity of the glue solution according to the degree of similarity of the peak areas of the first organic solvent of each test sample.

[0079] In steps S201-S205, the rest are the same as the above steps S101-S105 and will not be repeated here.

[0080] Figure 3 FIG. 1 is a flow chart of a method for evaluating the uniformity of a glue solution according to another exemplary embodiment of the present application. Figure 3 As shown, the evaluation method includes the following steps:

[0081] S301 , preparing a glue solution comprising a binder and a first organic solvent in a preset ratio.

[0082] S302, taking the glue liquid at different positions at the same time and the glue liquid at the same position at different times as test samples.

[0083] In this application, taking glue liquid from different positions at the same time and glue liquid from the same position at different times as test samples means taking glue liquid from different positions at the same time and taking glue liquid from the same position at different times, and all glue liquids are test samples.

[0084] The interpretation of taking glue at different positions at the same time is the same as that of the aforementioned step S102, and the interpretation of taking glue at the same position at different times is the same as that of the aforementioned step S202.

[0085] As a possible example, samples are taken from glue points 1, 2, 3, 4 and 5 at the same time (for example, 0h) as test samples No. 1-5, and then samples are taken from point 1 at 2h, 4h, 6h, 8h and 10h respectively as test samples No. 6-10. Test samples No. 1-5 and test samples No. 6-10 constitute all the test samples.

[0086] S303. Ultrasonic extraction and centrifugal separation of the test sample are performed, and the supernatant is filtered to obtain a mixed solution.

[0087] S304: Detect the mixed solution using a gas chromatography-mass spectrometer to obtain the peak area of ​​the first organic solvent.

[0088] S305 , judging the uniformity of the glue solution according to the degree of similarity of the peak areas of the first organic solvent of each test sample.

[0089] In some embodiments, the uniformity of the glue solution is determined as follows: the closer the peak areas of the first organic solvent of each test sample at different locations at the same time and at the same location at different times are, the better the uniformity of the glue solution. For example, in step S302, the closer the peak areas of the first organic solvent of test samples 1-5 and test samples 6-10 are, the better the uniformity of the glue solution.

[0090] Steps S301-S305 are basically the same as the rest of the aforementioned steps S101-S105 and steps S201-S205, and will not be repeated here.

[0091] Figure 4 FIG. 1 is a flow chart of a method for evaluating the uniformity of a glue solution according to another exemplary embodiment of the present application. Figure 4 As shown, the evaluation method includes the following steps:

[0092] S401 , preparing a glue solution comprising a binder and a first organic solvent in a preset ratio.

[0093] S402. Take the glue at different times and positions as test samples.

[0094] In this application, the glue solution at different times and locations refers to all glue solution samples obtained by sampling at different locations of the glue solution at different times, with a predetermined ratio (predetermined mass ratio) of the binder and the first organic solvent. Explanations of different times and different locations are provided in steps S202 and S102, respectively.

[0095] As a possible example, samples are taken from glue point 1, point 2, point 3, point 4 and point 5 at 0h, 2h, 4h, 6h and 8h respectively as test samples No. 1-25, and test samples No. 1-25 constitute all test samples.

[0096] S403. Ultrasonic extraction and centrifugal separation of the test sample are performed, and the supernatant is filtered to obtain a mixed solution.

[0097] S404: Detect the mixed solution using a gas chromatography-mass spectrometer to obtain the peak area of ​​the first organic solvent.

[0098] S405 , judging the uniformity of the glue solution according to the degree of similarity of the peak areas of the first organic solvent of each test sample.

[0099] The rest of steps S401-S405 are basically the same as the aforementioned steps S101-S105 and steps S201-S205, and will not be repeated here.

[0100] Figure 5 FIG. 1 is a flow chart of a method for evaluating the uniformity of a glue solution according to another exemplary embodiment of the present application. Figure 5 As shown, the evaluation method includes the following steps:

[0101] S501 , preparing a glue solution comprising a binder and a first organic solvent in a preset ratio.

[0102] S502. Take the glue liquid at different positions at the same time and the glue liquid at different positions at different times as test samples.

[0103] In step S502, the interpretation of the glue liquid at different positions at the same time is the same as that of step S102, and the interpretation of the glue liquid at different positions at different times is the same as that of step S402.

[0104] S503. Ultrasonic extraction and centrifugal separation of the test sample are performed, and the supernatant is filtered to obtain a mixed solution.

[0105] S504: Detect the mixed solution using a gas chromatography-mass spectrometer to obtain the peak area of ​​the first organic solvent.

[0106] S505 , judging the uniformity of the glue solution according to the degree of similarity of the peak areas of the first organic solvent of each test sample.

[0107] In some embodiments, the method for judging the uniformity of the glue solution is: the closer the peak areas of the first organic solvent of each test sample at different positions at the same time and at different positions at different times are, the better the uniformity of the glue solution.

[0108] Steps S501-S505 are basically the same as the rest of the aforementioned steps S101-S105 and steps S401-S405, and will not be repeated here.

[0109] Figure 6 FIG. 1 is a flow chart of a method for evaluating the uniformity of a glue solution according to another exemplary embodiment of the present application. Figure 6 As shown, the evaluation method includes the following steps:

[0110] S601 , preparing a glue solution comprising a binder and a first organic solvent in a preset ratio.

[0111] S602. Take the glue solution at the same position at different times and the glue solution at different positions at different times as test samples.

[0112] In step S602, the interpretation of the glue liquid at the same position at different times is the same as that in step S202, and the interpretation of the glue liquid at different positions at different times is the same as that in step S402.

[0113] As a possible example, samples are first taken from glue point 1, point 2, point 3, point 4 and point 5 at the same time (for example, 0h) as test samples No. 1-5, and then samples are taken at point 1, point 2, point 3, point 4 and point 5 at 2h, 4h, 6h, 8h and 10h respectively as test samples No. 6-30. Test samples No. 1-5 and test samples No. 6-30 constitute all the test samples.

[0114] S603. Ultrasonic extraction and centrifugal separation of the test sample are performed, and the supernatant is filtered to obtain a mixed solution.

[0115] S604: Detect the mixed solution using a gas chromatography-mass spectrometer to obtain the peak area of ​​the first organic solvent.

[0116] S605 , judging the uniformity of the glue solution according to the degree of similarity of the peak areas of the first organic solvent of each test sample.

[0117] In some embodiments, the uniformity of the glue solution is determined as follows: the closer the peak areas of the first organic solvent for each test sample at the same location at different times and at different locations at different times are, the better the uniformity of the glue solution. It should be noted that, taking one possible example in step S602 as an example, the closer the peak areas of the first organic solvent for test samples Nos. 1-5 and 6-30, constituting a total of 30 test samples, the better the uniformity of the glue solution.

[0118] Steps S601-S605 are basically the same as the rest of the aforementioned steps S201-S105 and steps S401-S405, and will not be repeated here.

[0119] Figure 7FIG. 1 is a flow chart of a method for evaluating the uniformity of a glue solution according to another exemplary embodiment of the present application. Figure 7 As shown, the evaluation method includes the following steps:

[0120] S701 , preparing a glue solution comprising a binder and a first organic solvent in a preset ratio.

[0121] S702. Take the glue liquid at different positions at the same time, the glue liquid at the same position at different times, and the glue liquid at different positions at different times as test samples.

[0122] In step 702, the interpretation of the glue liquid at different positions at the same time is the same as step S102, the interpretation of the glue liquid at the same position at different times is the same as step S202, and the interpretation of the glue liquid at different positions at different times is the same as step S402.

[0123] As a possible example, samples are first taken from glue point 1, point 2, point 3, point 4 and point 5 at the same time (for example, 0h) as test samples No. 1-5, and then samples are taken from point 1 at 2h, 4h and 6h respectively as test samples No. 6-9. At the same time, samples are taken from point 2 and point 4 at 2h, 4h and 6h respectively as test samples No. 10-15. Test samples No. 1-5, test samples No. 6-9 and test samples No. 10-15 constitute all the test samples.

[0124] S703. Ultrasonic extraction and centrifugal separation of the test sample are performed, and the supernatant is filtered to obtain a mixed solution.

[0125] S704: Detect the mixed solution using a gas chromatography-mass spectrometer to obtain the peak area of ​​the first organic solvent.

[0126] S705 . Determine the uniformity of the glue solution according to the degree of similarity of the peak areas of the first organic solvent of each test sample.

[0127] In some embodiments, the method for determining the uniformity of the glue solution is: the closer the peak areas of the first organic solvent of each test sample at different locations at the same time, at the same location at different times, and at different locations at different times are, the better the uniformity of the glue solution. It should be noted that, taking one possible example in step S702 as an example, that is, the closer the peak areas of the first organic solvent of test samples Nos. 1-5, 6-9, and 10-15, which constitute a total of 15 test samples, are, the better the uniformity of the glue solution.

[0128] Steps S701-S705 are basically the same as the rest of the aforementioned steps S101-S105, steps S201-S205 and steps S401-S405, and will not be repeated here.

[0129] It should be noted that in this application, when evaluating the uniformity of the glue solution, the uniformity of the glue solution can be determined to be good if it meets one of the following conditions:

[0130] Scenario 1: For the same glue solution, samples are taken at different locations at the same time. As long as the peak area of ​​the first organic solvent of each test sample is close enough and the relative standard deviation is below the preset value (e.g. Figure 1 );

[0131] Scenario 2: For the same glue at the same location, samples are taken at different times. As long as the peak area of ​​the first organic solvent of each test sample is close enough and the relative standard deviation is below the preset value (such as Figure 2 );

[0132] Scenario 3: For the same glue solution, samples are taken at different locations at the same time, or samples are taken at different times at the same location. As long as the peak area of ​​the first organic solvent of each test sample is close enough and the relative standard deviation is below the preset value (e.g. Figure 3 );

[0133] Scenario 4: For the same glue solution, samples are taken at different locations at different times. As long as the peak area of ​​the first organic solvent of each test sample is close enough and the relative standard deviation is below the preset value (e.g. Figure 4 );

[0134] Scenario 5: For the same glue solution, samples are taken at different locations at the same time, and samples are taken at different locations at different times. As long as the peak area of ​​the first organic solvent of each test sample is close enough and the relative standard deviation is below the preset value (e.g. Figure 5 );

[0135] Scenario 6: For the same glue solution, samples are taken at the same location at different times or at different locations at different times. As long as the peak area of ​​the first organic solvent of each test sample is close enough and the relative standard deviation is below the preset value (e.g. Figure 6 );

[0136] Scenario 7: For the same glue solution, samples are taken at different locations at the same time, samples are taken at the same location at different times, and samples are taken at different locations at different times. As long as the peak area of ​​the first organic solvent of each test sample is close enough and the relative standard deviation is below the preset value (e.g. Figure 7 ).

[0137] It should be noted that the more dimensions of glue liquid are tested, the better the glue liquid uniformity is. That is, compared with the above-mentioned scenarios 1, 2, and 4, the glue liquid uniformity evaluated according to scenarios 3, 5, 6, and 7 is better, and scenario 7 is the best.

[0138] The glue uniformity evaluation method of the embodiment of the present application can bring the following beneficial effects: it helps to improve the accuracy of the glue uniformity test and can greatly shorten the test time. At the same time, it does not require the use of an oven, there is no component volatilization, and it does not pollute the environment.

[0139] Certain features of the present technology are further illustrated in the following non-limiting examples.

[0140] Verification experiment example

[0141] This verification experiment was conducted using the following method to compare different PVDF / NMP adhesives:

[0142] (1) PVDF and NMP were added into a blender at preset mass ratios of 1:99, 3:97, 5:95, 7:93, and 9:91, respectively, and stirred for 240 min at a stirring speed of 600 rpm to prepare PVDF / NMP gel solutions with PVDF contents of 1 wt%, 3 wt%, 5 wt%, 7 wt%, and 9 wt%, respectively.

[0143] (2) 1 g of PVDF / NMP glue with different preset mass ratios was weighed, and 10 ml of methanol (chromatographic grade) organic solvent was added to each solution for ultrasonic extraction. After centrifugation, the supernatant was collected and filtered to obtain a mixed solution. The ultrasonic extraction time was 5 min, the frequency was 40 kHz, and the power was 250 W; the centrifugation time was 5 min, and the speed was 10,000 rpm. The filter membrane used for filtration was a 0.22 μm oil-based filter membrane.

[0144] (3) Then, 10 μl of the mixed solution was taken and diluted 100 times with methanol to obtain test solutions of PVDF / NMP glue with different preset mass ratios.

[0145] (4) Each test solution was detected using the SIM / SCAN mixed mode of GCMS to obtain the quantitative peak area of ​​NMP, and the PVDF / NMP gel solutions with different contents were compared by comparing the peak areas.

[0146] (5) Chromatographic determination conditions in SIM / SCAN hybrid mode of GCMS include:

[0147] The chromatographic column is Rtx-MS, and the column dimensions are 30 m (length) × 0.25 mm (inner diameter) × 0.25 μm (film thickness);

[0148] The carrier gas is helium with a purity of 99.999%;

[0149] The injection volume was 1 μL, and the split ratio was 30:1;

[0150] The number of solvent rinses (before injection) is 3 times; the number of solvent rinses (after injection) is 3 times; the number of sample rinses is 2 times;

[0151] The injection port temperature was 250 °C;

[0152] Heating program: initial temperature 100 °C, maintain for 3 min; then increase the temperature to 120 °C at a rate of 5 °C / min, and then increase the temperature to 220 °C at a rate of 10 °C / min;

[0153] The comparative data is shown in Table 1:

[0154] Table 1 Comparison of peak areas of PVDF / NMP glues with different preset mass ratios

[0155] PVDF content / % 1 3 5 7 9 NMP peak area 10239655 10082488 9814626 9600839 9422832

[0156] In this verification experiment, by comparing the PVDF content and NMP peak area in PVDF / NMP glues with different preset mass ratios, it can be seen from Table 1 that as the PVDF content increases, the NMP peak area gradually decreases, which is consistent with the trend of gradually decreasing NMP content. The relationship between the PVDF content and the NMP peak area conforms to y=-105765x+1E+07, where x represents the PVDF content, y represents the NMP peak area, and R 2 =0.994.

[0157] It can be seen that this verification experiment detects R 2 >0.99, proving that it is feasible to compare the uniformity of PVDF / NMP glue by peak area.

[0158] Example 1

[0159] The method for evaluating the uniformity of PVDF / NMP glue in this embodiment includes the following steps:

[0160] (1) PVDF and NMP were added into a blender at a preset mass ratio of 5:95 and stirred for 240 min at a stirring speed of 600 rpm to prepare a PVDF / NMP glue solution with a PVDF mass fraction of 5%.

[0161] (2) Prepare 5 centrifuge tubes of the same specifications. At the same time (0 h), use a disposable dropper to transfer 1 g of PVDF / NMP glue from different positions of the prepared 5 wt% PVDF / NMP glue into different centrifuge tubes. The sampling positions are 1 cm, 3 cm, 5 cm, 7 cm, and 9 cm from the upper surface of the glue. Then, add 10 ml of methanol (chromatographically pure at least 99.9%) into each centrifuge tube. Then, ultrasonically extract the solution in each centrifuge tube, centrifuge, and then take the supernatant from the centrifugation and filter the supernatant to obtain 5 mixed solutions. The ultrasonic extraction time is 5 min, the frequency is 40 kHz, and the power is 250 W. The centrifugation time is 5 min, and the rotation speed is 10,000 rpm. The filter membrane used for filtration is a 0.22 μm oil filter membrane.

[0162] (3) Take 10 μl of each mixed solution and dilute it 100 times with methanol (chromatographically pure above 99.9%) to obtain the test solution.

[0163] (4) Each test solution was tested using the SIM / SCAN hybrid mode of the GCMS to obtain the quantitative peak area of ​​NMP of each test solution. The homogeneity of the PVDF / NMP glue solution was determined by comparing the NMP peak area of ​​each test solution.

[0164] (5) Chromatographic determination conditions in SIM / SCAN hybrid mode of GCMS include:

[0165] The chromatographic column is Rtx-MS, and the column dimensions are 30 m (length) × 0.25 mm (inner diameter) × 0.25 μm (film thickness);

[0166] The carrier gas is helium with a purity of 99.999%;

[0167] The injection volume was 1 μL, and the split ratio was 30:1;

[0168] The number of solvent rinses (before injection) is 3 times; the number of solvent rinses (after injection) is 3 times; the number of sample rinses is 2 times;

[0169] The injection port temperature was 250 °C;

[0170] Heating program: initial temperature 100 °C, maintain for 3 min; increase the temperature to 120 °C at a rate of 5 °C / min, and increase the temperature to 220 °C at a rate of 10 °C / min;

[0171] The test data of each solution to be tested in this embodiment are shown in Table 2.

[0172] Table 2 Test data of each test solution in Example 1

[0173] Sampling position / cm 1 3 5 7 9 NMP peak area 9791725 9817897 9783016 9831446 9780723

[0174] The relative standard deviation of the NMP peak area obtained in this example is 0.23%, which is less than the preset value of 0.5%, indicating that the uniformity of the PVDF / NMP glue at different positions is good, and indirectly indicating that the PVDF / NMP glue of this example has good uniformity.

[0175] The total time required for the PVDF / NMP glue homogeneity evaluation method of this embodiment (excluding the stirring time in step (1)) is 20*5=100 min. Here, 20 is the time required for each test solution from the preparation of the glue solution (excluding the stirring time in step (1)) to the completion of the test, including: 2 min for weighing PVDF and NMP, 5 min for ultrasonic extraction, 5 min for centrifugation, 1 min for filtration, and 7 min for GCMS testing; 5 is the number of test solutions.

[0176] Example 2

[0177] The method for evaluating the uniformity of PVDF / NMP glue in this embodiment includes the following steps:

[0178] (1) PVDF and NMP were added into a blender at a preset mass ratio of 5:95 and stirred for 240 min at a stirring speed of 600 rpm to prepare a PVDF / NMP glue solution with a PVDF mass fraction of 5%.

[0179] (2) Prepare 5 centrifuge tubes of the same specifications. At different times (0h, 2h, 4h, 6h, 8h), use a disposable dropper to transfer 1g of PVDF / NMP glue from the same position of the prepared 5wt% PVDF / NMP glue (1cm from the upper surface of the glue) into different centrifuge tubes. Add 10ml of methanol (chromatographically pure at least 99.9%) into each centrifuge tube. Then, ultrasonically extract the solution in each centrifuge tube, and then centrifuge. After that, take the supernatant of the centrifuged solution and filter the supernatant to obtain each mixed solution. The ultrasonic extraction time is 5min, the frequency is 40kHz, and the power is 250W; the centrifugation time is 5min, and the speed is 10000rpm. The filter membrane used for filtration is a 0.22μm oil filter membrane.

[0180] (3) Take 10 μl of each mixed solution and dilute it 100 times with methanol (chromatographically pure above 99.9%) to obtain the test solution.

[0181] (4) Each test solution was tested using the SIM / SCAN hybrid mode of the GCMS to obtain the quantitative peak area of ​​NMP of each test solution. The homogeneity of the PVDF / NMP glue solution was determined by comparing the NMP peak area of ​​each test solution.

[0182] (5) Chromatographic determination conditions in SIM / SCAN hybrid mode of GCMS include:

[0183] The chromatographic column is Rtx-MS, and the column dimensions are 30 m (length) × 0.25 mm (inner diameter) × 0.25 μm (film thickness);

[0184] The carrier gas is helium with a purity of 99.999%;

[0185] The injection volume was 1 μL, and the split ratio was 30:1;

[0186] The number of solvent rinses (before injection) is 3 times; the number of solvent rinses (after injection) is 3 times; the number of sample rinses is 2 times;

[0187] The injection port temperature was 250 °C;

[0188] Heating program: initial temperature 100 °C, maintain for 3 min; increase the temperature to 120 °C at a rate of 5 °C / min, and increase the temperature to 220 °C at a rate of 10 °C / min;

[0189] The test data of each solution to be tested in this embodiment are shown in Table 3.

[0190] Table 3 Test data of each test solution in Example 2

[0191] Sampling time / h 0 2 4 6 8 NMP peak area 9791725 9837099 9793914 9815241 9800445

[0192] The relative standard deviation of the NMP peak area obtained in this example is 0.192%, which is less than the preset value of 0.5%, indicating that the uniformity of the PVDF / NMP glue solution is good over the standing time, and indirectly indicating that the PVDF / NMP glue solution in this example has good uniformity.

[0193] The total time required for the PVDF / NMP glue homogeneity evaluation method of this embodiment (excluding the stirring time in step (1) and the sample resting time in step (2)) is 20*5=100 min. Here, 20 is the time required for each test solution from the preparation of the glue solution (excluding the stirring time in step (1)) to the completion of the test, including: 2 min for weighing PVDF and NMP, 5 min for ultrasonic extraction, 5 min for centrifugation, 1 min for filtration, and 7 min for GCMS testing; 5 is the number of test solutions.

[0194] Example 3

[0195] The method for evaluating the uniformity of PVDF / NMP glue in this embodiment includes the following steps:

[0196] (1) PVDF and NMP were added into a blender at a preset mass ratio of 5:95 and stirred for 240 min at a stirring speed of 600 rpm to prepare a PVDF / NMP glue solution with a PVDF mass fraction of 5%.

[0197] (2) Prepare 6 centrifuge tubes of the same specifications. At different times (0h, 2h, 4h), use a disposable dropper to transfer 1g of PVDF / NMP glue from different positions of the prepared 5wt% PVDF / NMP glue into different centrifuge tubes. The sampling positions are 1cm and 9cm away from the upper surface of the glue. Then, add 10ml of methanol (chromatographically pure at 99.9% or more) organic solvent to each centrifuge tube. Then, ultrasonically extract the solution in each centrifuge tube, and then centrifuge. After that, take the supernatant of the centrifuged separation and filter the supernatant to obtain 6 mixed solutions. The ultrasonic extraction time is 5min, the frequency is 40kHz, and the power is 250W. The centrifugation time is 5min and the speed is 10000rpm. The filter membrane used for filtration is a 0.22μm oil filter membrane.

[0198] (3) Take 10 μl of each mixed solution and dilute it 100 times with methanol (chromatographically pure above 99.9%) to obtain the test solution.

[0199] (4) Each test solution was tested using the SIM / SCAN hybrid mode of the GCMS to obtain the quantitative peak area of ​​NMP of each test solution. The homogeneity of the PVDF / NMP glue solution was determined by comparing the NMP peak area of ​​each test solution.

[0200] (5) Chromatographic determination conditions in SIM / SCAN hybrid mode of GCMS include:

[0201] The chromatographic column is Rtx-MS, and the column dimensions are 30 m (length) × 0.25 mm (inner diameter) × 0.25 μm (film thickness);

[0202] The carrier gas is helium with a purity of 99.999%;

[0203] The injection volume was 1 μL, and the split ratio was 30:1;

[0204] The number of solvent rinses (before injection) is 3 times; the number of solvent rinses (after injection) is 3 times; the number of sample rinses is 2 times;

[0205] The injection port temperature was 250 °C;

[0206] Heating program: initial temperature 100 °C, maintain for 3 min; increase the temperature to 120 °C at a rate of 5 °C / min, and increase the temperature to 220 °C at a rate of 10 °C / min;

[0207] The test data of each solution to be tested in this embodiment are shown in Table 4.

[0208] Table 4 Test data of each test solution in Example 3

[0209]

[0210]

[0211] The relative standard deviation of the NMP peak area obtained in this example is 0.22%, which is less than the preset value of 0.5%, indicating that the uniformity of the PVDF / NMP glue solution is good over the standing time, and indirectly indicating that the PVDF / NMP glue solution in this example has good uniformity.

[0212] The total time required for the PVDF / NMP glue homogeneity evaluation method of this embodiment (excluding the stirring time in step (1) and the sample resting time in step (2)) is 20*6=120 minutes. Here, 20 is the time required for each test solution from the preparation of the glue solution (excluding the stirring time in step (1)) to the completion of the test, including: 2 minutes for weighing PVDF and NMP, 5 minutes for ultrasonic extraction, 5 minutes for centrifugation, 1 minute for filtration, and 7 minutes for GCMS testing; 6 is the number of test solutions.

[0213] Example 4

[0214] The method is the same as that of Example 1, except that a PVDF / NMP glue solution with a PVDF mass fraction of 9% is prepared.

[0215] The test data of each solution to be tested in this embodiment are shown in Table 5.

[0216] Table 5 Test data of each test solution in Example 4

[0217] Sampling position / cm 1 3 5 7 9 NMP peak area 9430709 9374014 9443489 9419646 9413132

[0218] The relative standard deviation of the NMP peak area obtained in this example is 0.28%, which is less than the preset value of 0.5%, indicating that the PVDF / NMP glue has good uniformity at different positions, and indirectly indicates that the PVDF / NMP glue of this example has good uniformity.

[0219] The total time consumed by the PVDF / NMP glue uniformity evaluation method in this embodiment is 20*5=100 minutes.

[0220] Example 5

[0221] The method is the same as that of Example 2, except that a PVDF / NMP glue solution with a PVDF mass fraction of 9% is prepared.

[0222] The test data of each solution to be tested in this embodiment are shown in Table 6.

[0223] Table 6 Test data of each test solution in Example 5

[0224] Sampling time / h 0 2 4 6 8 NMP peak area 9430709 9377161 9397724 9443617 9473941

[0225] The relative standard deviation of the NMP peak area obtained in this example is 0.40%, which is less than the preset value of 0.5%, indicating that the uniformity of the PVDF / NMP glue solution is good over the standing time, and indirectly indicating that the PVDF / NMP glue solution in this example has good uniformity.

[0226] The total time consumed by the PVDF / NMP glue uniformity evaluation method in this embodiment is 20*5=100 minutes.

[0227] Example 6

[0228] The method is the same as that of Example 3, except that a PVDF / NMP glue solution with a PVDF mass fraction of 9% is prepared.

[0229] The test data of each solution to be tested in this embodiment are shown in Table 7.

[0230] Table 7 Test data of each test solution in Example 6

[0231] Sampling time / h 0 2 4 0 2 4 Sampling position / cm 1 1 1 9 9 9 NMP peak area 9430709 9377161 9397724 9413132 9391827 9345904

[0232] The relative standard deviation of the NMP peak area obtained in this example is 0.31%, which is less than the preset value of 0.5%, indicating that the uniformity of the PVDF / NMP glue solution is good over the standing time, and indirectly indicating that the PVDF / NMP glue solution of this example has good uniformity.

[0233] The total time consumed by the PVDF / NMP glue uniformity evaluation method in this embodiment is 20*6=120 minutes.

[0234] Example 7

[0235] The method is the same as that of Example 1, except that the binder is polyacrylonitrile (PAN).

[0236] The test data of each solution to be tested in this embodiment are shown in Table 8.

[0237] Table 8 Test data of each test solution in Example 7

[0238] Sampling position / cm 1 3 5 7 9 NMP peak area 9712828 9812720 9700018 9730521 9728985

[0239] The relative standard deviation of the NMP peak area obtained in this example is 0.45%, which is less than the preset value of 0.5%, indicating that the PAN / NMP glue solution has good uniformity at different positions, and indirectly indicates that the PAN / NMP glue solution of this example has good uniformity.

[0240] The total time consumed by the PAN / NMP glue uniformity evaluation method in this embodiment is 20*5=100 minutes.

[0241] Example 8

[0242] The method is the same as that of Example 2, except that the binder is polyacrylonitrile (PAN).

[0243] The test data of each solution to be tested in this embodiment are shown in Table 9.

[0244] Table 9 Test data of each test solution in Example 8

[0245] Sampling time / h 0 2 4 6 8 NMP peak area 9693685 9811924 9728985 9734572 9767207

[0246] The relative standard deviation of the NMP peak area obtained in this example is 0.46%, which is less than the preset value of 0.5%, indicating that the uniformity of the PAN / NMP glue solution is good over the standing time, and indirectly indicating that the PAN / NMP glue solution of this example has good uniformity.

[0247] The total time consumed by the PAN / NMP glue uniformity evaluation method in this embodiment is 20*5=100 minutes.

[0248] Example 9

[0249] The method is the same as that of Example 3, except that the binder is polyacrylonitrile (PAN).

[0250] The test data of each test solution in this embodiment are shown in Table 10.

[0251] Table 10 Test data of each test solution in Example 9

[0252] Sampling time / h 0 2 4 0 2 4 Sampling position / cm 1 1 1 9 9 9 NMP peak area 9693685 9811924 9728985 9728985 9745904 9780783

[0253] The relative standard deviation of the NMP peak area obtained in this example is 0.43%, which is less than the preset value of 0.5%, indicating that the uniformity of the PAN / NMP glue solution is good over the standing time, and indirectly indicating that the PAN / NMP glue solution of this example has good uniformity.

[0254] The total time consumed by the PAN / NMP glue uniformity evaluation method in this embodiment is 20*6=120 minutes.

[0255] Example 10

[0256] The method is the same as that of Example 1, except that the first organic solvent is dimethylacetamide (DMA).

[0257] The test data of each test solution in this embodiment are shown in Table 11.

[0258] Table 11 Test data of each test solution in Example 10

[0259] Sampling position / cm 1 3 5 7 9 DMA peak area 7854349 7789474 7815766 7785855 7795163

[0260] The relative standard deviation of the DMA peak area obtained in this example is 0.46%, which is less than the preset value of 0.5%, indicating that the PVDF / DMA glue has good uniformity at different positions, and also indirectly indicates that the PVDF / DMA glue of this example has good uniformity.

[0261] The total time consumed by the PVDF / DMA glue uniformity evaluation method in this embodiment is 20*5=100 minutes.

[0262] Example 11

[0263] The method is the same as that of Example 2, except that the first organic solvent is dimethylacetamide (DMA).

[0264] The test data of each test solution in this embodiment are shown in Table 12.

[0265] Table 12 Test data of each test solution in Example 11

[0266] Sampling time / h 0 2 4 6 8 DMA peak area 7854349 7819190 7849405 7783619 7812654

[0267] The relative standard deviation of the DMA peak area obtained in this example is 0.37%, which is less than the preset value of 0.5%, indicating that the uniformity of the PVDF / DMA glue solution is good over the standing time, and also indirectly indicating that the PVDF / DMA glue solution of this example has good uniformity.

[0268] The total time consumed by the PVDF / DMA glue uniformity evaluation method in this embodiment is 20*5=100 minutes.

[0269] Example 12

[0270] The method is the same as that of Example 3, except that the first organic solvent is dimethylacetamide (DMA).

[0271] The test data of each test solution in this embodiment are shown in Table 13.

[0272] Table 13 Test data of each test solution in Example 12

[0273] Sampling time / h 0 2 4 0 2 4 Sampling position / cm 1 1 1 9 9 9 DMA peak area 7854349 7819190 7849405 7795163 7815898 7766735

[0274] The relative standard deviation of the DMA peak area obtained in this example is 0.42%, which is less than the preset value of 0.5%, indicating that the uniformity of the PVDF / DMA glue solution is good over the standing time, and indirectly indicating that the PVDF / DMA glue solution in this example has good uniformity.

[0275] The total time consumed by the PVDF / DMA glue uniformity evaluation method in this embodiment is 20*6=120 minutes.

[0276] Comparative Example 1

[0277] This comparative example was tested for the uniformity of the PVDF / NMP glue solution in Example 1 according to the following general baking test method:

[0278] First, take a piece of foil, weigh it and peel it, then take 5 groups of glue from different positions according to Example 1, and evenly apply 1g of glue on the foil, then put it into a blast oven and bake it at 120℃ for 2h. After baking, weigh it and calculate the solid content.

[0279] The test results of each glue solution to be tested in this comparative example are shown in Table 14.

[0280] Table 14 Test results of each test glue solution in comparative example 1

[0281] Different positions / cm 1 3 5 7 9 Foil weight / g 0.3237 0.3852 0.4983 0.3413 0.4277 Sample weight (before baking) / g 2.1499 3.6735 2.4353 2.6892 2.8106 Sample + foil weight (after baking) / g 0.4349 0.5736 0.6236 0.4772 0.5719 Sample weight (after baking) / g 0.1112 0.1884 0.1253 0.1359 0.1442 Solid content / % 5.17％ 5.13％ 5.15％ 5.05％ 5.13％

[0282] The relative standard deviation of the solid content of the PVDF / DMA glue measured by the drying method in this comparative example is 0.86%.

[0283] The PVDF / NMP glue uniformity evaluation method of this comparative example takes a total of 2 hours, and NMP volatilizes during the test.

[0284] It should be noted that, if the test method of this comparative example is used to test the glue solution at the same location at different times as in Example 2, the baking time at each different time point is 2 hours, so the total test time is 2*5=10 hours.

[0285] Comparative Example 2

[0286] This comparative example was conducted to test the uniformity of the PVDF / NMP adhesive in Example 1 according to the following general viscosity test method:

[0287] According to Example 1, 5 groups of glue solutions at different positions were taken and viscosity tests were performed.

[0288] The test results of each glue solution to be tested in this comparative example are shown in Table 15.

[0289] Table 15 Test results of each test glue solution of comparative example 2

[0290] Different positions / cm 1 3 5 7 9 Viscosity / Pa.s 502.3 514.6 521.6 495.1 513.4

[0291] The relative standard deviation of the viscosity of the PVDF / DMA glue measured by the drying method in this comparative example is 2.07%.

[0292] The total amount of glue required during the test of the PVDF / NMP glue uniformity evaluation method in this comparative example is about 50 ml, the glue test time at each position is 5 minutes, and the total time consumed is 5*5=25 minutes. Although the test time is relatively short, this method is affected by the viscometer rotor, speed and glue temperature. If the viscosity changes over time, the rotor and speed need to be replaced.

[0293] In this application, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0294] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for evaluating the uniformity of a glue solution, characterized in that: include: A glue solution comprising a binder and a first organic solvent in a preset ratio is configured; the binder comprises at least one of polyvinylidene fluoride, polyacrylonitrile, and polyamide, and the first organic solvent comprises at least one of N-methylpyrrolidone, dimethylacetamide, dimethylformamide, and dimethyl sulfoxide; Taking the glue solution at different positions at the same time or / and the glue solution at the same position at different times or / and the glue solution at different positions at different times as test samples; After ultrasonic extraction and centrifugal separation of the test sample, the supernatant is filtered to obtain a mixed solution; The method for ultrasonic extraction of the test sample comprises: mixing the test sample with a second organic solvent, wherein the second organic solvent is at least one of methanol, dichloromethane, and n-hexane with a chromatographic purity of 99.9% or more; Detecting the mixed solution using a gas chromatography-mass spectrometer to obtain a peak area of ​​the first organic solvent; Determining the uniformity of the glue solution based on the closeness of the peak areas of the first organic solvent of each test sample; The method for judging the uniformity of the glue solution is: the closer the peak areas of the first organic solvent of each test sample are, the better the uniformity of the glue solution.

2. The method for evaluating the uniformity of the glue solution according to claim 1, wherein: Judging the uniformity of the glue solution according to the closeness of the peak areas of the first organic solvent of each of the test samples includes: Obtaining the relative standard deviation of the peak area of ​​the first organic solvent of each test sample; If the relative standard deviation is below a preset value, it is judged that the uniformity of the glue solution is good; If the relative standard deviation is greater than the preset value, it is determined that the glue solution has poor uniformity.

3. The method for evaluating the uniformity of the glue solution according to claim 2, wherein: The preset value is 0.2-0.5%.

4. The method for evaluating the uniformity of the glue solution according to claim 1, wherein: The preset ratio of the binder to the first organic solvent is a preset mass ratio, and the preset mass ratio is (1-9): (99-91).

5. The method for evaluating the uniformity of the glue solution according to claim 1, wherein: The method for ultrasonically extracting the test sample further comprises the step of ultrasonically extracting the test sample for 3-8 minutes under the conditions of 30-50 kHz and 200-300 W after mixing the test sample with a second organic solvent; And / or, the centrifugal separation time is 3-8 min, and the centrifugal separation speed is 8000-12000 rpm; And / or, the filter membrane used for the filtration is an oil-based filter membrane.

6. The method for evaluating the uniformity of the glue solution according to claim 5, characterized in that: The test sample and the second organic solvent are mixed in an amount of 5-50 ml of the second organic solvent for every 500.0-1000.0 mg of the test sample.

7. The method for evaluating the uniformity of the glue solution according to claim 1, wherein: The mixed solution was detected using a SIM / SACN mixed mode in the gas chromatography-mass spectrometry; And / or, the gas chromatography measurement conditions in the gas chromatography-mass spectrometry include: the chromatographic column is Rtx-MS, the chromatographic column length is 30m, the chromatographic column inner diameter is 0.25mm, the chromatographic column film thickness is 0.25μm, the carrier gas is helium, and the helium purity is 99.999%; the injection volume is 1μL, the split ratio is 20-30:1; the number of solvent rinses before injection is 3-5 times; the number of solvent rinses after injection is 3-5 times; the number of sample rinses is 2-3 times; the injection port temperature is 230-250℃; the heating program is: initial temperature 90-100℃, maintain 3-5min, then heat up to 120-150℃ at a heating rate of 5-10℃ / min, and then heat up to 220-250℃ at a heating rate of 5-10℃ / min.

8. The method for evaluating the uniformity of the glue solution according to claim 1, wherein: The step of preparing the glue solution is carried out under stirring conditions, the stirring time is 200-280 minutes, and the stirring speed is 500-700 rpm; And / or, the method for evaluating the uniformity of the glue solution further includes the step of diluting the mixed solution with a third organic solvent before using a gas chromatography-mass spectrometer to detect the mixed solution.

9. The method for evaluating the uniformity of the glue solution according to claim 8, wherein: The third organic solvent is at least one of methanol, dichloromethane, and n-hexane with a chromatographic purity of 99.9% or more; And / or, the dilution ratio is 50-200 times.

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