Carbon nano tube body resistivity test diaphragm, preparation method thereof and carbon nano tube body resistivity test method

Abstract

The invention provides a carbon nanotube resistivity test diaphragm, a preparation method thereof and a carbon nanotube resistivity test method. The carbon nanotube resistivity test diaphragm comprises a carbon nanotube to be tested, an active material and a binder. According to the invention, gaps among the to-be-tested carbon nanotubes can be filled by the active material, and the to-be-tested carbon nanotubes and the active material can be fixed by the binder, so that the stability of the to-be-tested carbon nanotubes in the carbon nanotube body resistivity test diaphragm is improved; therefore, the test accuracy of the volume resistivity of the to-be-tested carbon nanotube obtained by testing the volume resistivity of the diaphragm is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly relates to a carbon nanotube bulk resistivity test diaphragm, a preparation method thereof, and a carbon nanotube bulk resistivity test method. Background Art

[0002] Carbon nanotubes are one-dimensional quantum materials with a special structure and have many excellent electrical properties. Their bulk resistivity is one of the important indicators to measure their electrical properties. By testing the bulk resistivity of carbon nanotubes, the conductivity of carbon nanotubes can be evaluated, which is of great significance for the application of carbon nanotubes in the fields of electronics, energy, sensors, etc. The bulk resistivity of carbon nanotubes is affected by various factors, such as tube diameter, tube wall spacing, defect number, preparation method, and preparation conditions.

[0003] In the related art, the method for testing the bulk resistivity of carbon nanotubes is to directly test the bulk resistivity of carbon nanotube powders. However, there are voids between the crystal-shaped carbon nanotube powder particles, resulting in poor material stability, and pressure is applied during the test, which causes the tubular carbon nanotubes to break, and thus the accuracy of the test results is insufficient. Summary of the Invention

[0004] Embodiments of the present invention provide a carbon nanotube bulk resistivity test diaphragm, a preparation method thereof, and a carbon nanotube bulk resistivity test method, which can improve the technical problem of insufficient test accuracy existing in the resistivity test of existing carbon nanotube materials.

[0005] In a first aspect, embodiments of the present invention provide a carbon nanotube bulk resistivity test diaphragm, which includes a carbon nanotube to be tested, an active material, and a binder.

[0006] In one embodiment, the thickness of the carbon nanotube bulk resistivity test diaphragm is 100 μm to 200 μm; and / or

[0007] the carbon nanotube bulk resistivity test diaphragm is a disc; and / or

[0008] the mass percentage content of the carbon nanotube to be tested in the carbon nanotube bulk resistivity test diaphragm is 0.01% to 0.1%; and / or

[0009] the mass percentage content of the active material in the carbon nanotube bulk resistivity test diaphragm is 60% to 95%; and / or

[0010] the mass percentage content of the binder in the carbon nanotube bulk resistivity test diaphragm is 5% - 10.6%.

[0011] In one embodiment, the carbon nanotube to be tested is applied to the negative electrode of a battery, and the active material is a negative electrode active material;

[0012] The carbon nanotubes to be tested are applied to the positive electrode of the battery, and the active material is the positive electrode active material.

[0013] In one embodiment, the negative electrode active material includes one or more of graphite and silicon; and / or

[0014] The active material is the negative electrode active material, and the binder includes one or more of styrene-butadiene rubber, carboxymethyl cellulose, polyacrylic acid, and polytetrafluoroethylene.

[0015] In one embodiment, the negative electrode active material includes graphite and silicon, and the mass ratio of graphite to silicon is (30 - 60):(30 - 60); and / or

[0016] The active material is the negative electrode active material, the binder includes styrene-butadiene rubber and carboxymethyl cellulose, and the mass ratio of styrene-butadiene rubber to carboxymethyl cellulose is (5 - 10):(0.2 - 0.6).

[0017] In one embodiment, the positive electrode active material includes one or more of metal oxides, polyanion salts, fluorides, sulfides, and selenides; and / or

[0018] The active material is the positive electrode active material, the binder includes polyvinylidene fluoride, and the mass percentage content of polyvinylidene fluoride in the carbon nanotube body resistivity test film is 5% - 10%; and / or

[0019] The active material is the positive electrode active material, and the carbon nanotube body resistivity test film also includes conductive carbon black, and the mass percentage content of conductive carbon black in the carbon nanotube body resistivity test film is 10% - 15%.

[0020] In a second aspect, an embodiment of the present invention provides a method for preparing a carbon nanotube body resistivity test film, including:

[0021] Providing carbon nanotubes to be tested, an active material, and a binder, mixing them and then performing film-forming treatment to obtain a carbon nanotube body resistivity test film.

[0022] In one embodiment, the mixing includes: mixing the carbon nanotubes, the active material, and the binder in a solvent to obtain a slurry;

[0023] The film-forming treatment includes: disposing the slurry on an insulating film to form a wet film layer, and drying the wet film layer.

[0024] In one embodiment, the solid content of the slurry is 23% - 25%; and / or

[0025] The material of the insulating film includes polyethylene terephthalate; and / or

[0026] The active material is a negative electrode active material, and the solvent is water; and / or

[0027] The active material is a negative electrode active material, the drying temperature is 83°C - 87°C, and the drying time does not exceed 2 h; and / or

[0028] The active material is a positive electrode active material, and the solvent is N-methylpyrrolidone; and / or

[0029] The active material is a positive electrode active material, the drying temperature is 102°C - 108°C, and the drying time does not exceed 2 h.

[0030] In a third aspect, an embodiment of the present invention provides a method for testing the bulk resistivity of a carbon nanotube body, including:

[0031] Providing a carbon nanotube body resistivity test film as described above or a carbon nanotube body resistivity test film prepared by the method for preparing the carbon nanotube body resistivity test film as described above, testing the bulk resistivity of the carbon nanotube body resistivity test film, and obtaining the bulk resistivity of the film;

[0032] Based on the bulk resistivity of the film, the bulk resistivity of the active material, and the binder bulk resistivity, obtaining the bulk resistivity of the to-be-tested carbon nanotube.

[0033] In an embodiment, there are multiple carbon nanotube body resistivity test films, the diameter of each carbon nanotube body resistivity test film is 10 mm - 20 mm, the mass difference between every two carbon nanotube body resistivity test films ≤ 0.8%, and the thickness difference between every two carbon nanotube body resistivity test films is ≤ 0.8%; and / or

[0034] The method for testing the bulk resistivity of the carbon nanotube body resistivity test film is the four-probe resistivity test method.

[0035] Advantageous effects of the embodiments of the present invention:

[0036] In the embodiments of the present invention, the active material can fill the gaps between the to-be-tested carbon nanotubes, and the binder can fix the to-be-tested carbon nanotubes and the active material, thereby improving the stability of the to-be-tested carbon nanotubes in the carbon nanotube body resistivity test film, and further improving the test accuracy of the bulk resistivity of the to-be-tested carbon nanotubes obtained by testing the bulk resistivity of the test film. Detailed implementation manners

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the present invention. The terms used in the description of the present invention in this specification are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0039] In this application, "at least one" means one or more, and "multiple" means two or more. "One or more", "at least one (item) below" or similar expressions refer to any combination of these items, including any combination of single (item) or plural items. For example, "at least one (item) of a, b, or c", or "at least one (item) of a, b, and c" can both represent: a, b, c, a - b (that is, a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0040] The various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of this application; therefore, it should be considered that the described range description has specifically disclosed all possible sub - ranges and single values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub - ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within that range, such as 1, 2, 3, 4, 5, and 6, regardless of what the range is. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0041] The technical solution of this application is as follows:

[0042] In a first aspect, an embodiment of the present invention provides a carbon nanotube body resistivity test film, which includes a carbon nanotube to be tested, an active material, and a binder.

[0043] In this application, the active material can fill the gaps between the carbon nanotubes to be tested, and the binder can fix the carbon nanotubes to be tested and the active material, thereby improving the stability of the carbon nanotubes to be tested in the carbon nanotube bulk resistivity test film, and further improving the test accuracy of the bulk resistivity of the carbon nanotubes to be tested obtained from the bulk resistivity of the test film.

[0044] It can be understood that the carbon nanotubes to be tested, the active material, and the binder are uniformly distributed in the carbon nanotube bulk resistivity test film. Therefore, the bulk resistivity of the carbon nanotubes to be tested can be obtained by subtracting the bulk resistivity of the active material and the bulk resistivity of the binder from the measured bulk resistivity of the carbon nanotube bulk resistivity test film. The bulk resistivity of the active material and the bulk resistivity of the binder are fixed values.

[0045] In one embodiment, the thickness of the carbon nanotube bulk resistivity test film is 100 μm to 200 μm, and can be, for example, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, etc. Thus, the surface flatness of the carbon nanotube bulk resistivity test film can be controlled, and the influence of the air in the gaps on the surface of the test film on the accuracy of the test results can be reduced, thereby improving the stability of the test results. If the film thickness is too thick, more pores will be formed on the surface due to solvent evaporation during drying, and the surface flatness will be worse.

[0046] In one embodiment, the carbon nanotube bulk resistivity test film is a disc. Thus, when measuring the bulk resistivity of the carbon nanotube bulk resistivity test film, the disc-shaped film can make the current spread more evenly on the film, thereby improving the accuracy of the test results.

[0047] In one embodiment, the mass percentage content of the carbon nanotubes to be tested in the carbon nanotube bulk resistivity test film is 0.01% to 0.1%, and can be, for example, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, etc.

[0048] In one embodiment, the mass percentage content of the active material in the carbon nanotube bulk resistivity test film is 60% to 95%, and can be, for example, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, etc.

[0049] In one embodiment, the mass percentage content of the binder in the carbon nanotube bulk resistivity test film is 5% - 10.6%, and can be, for example, 5%, 6%, 7%, 8%, 9%, 10%, 10.6%, etc.

[0050] In this application, by controlling the contents of the carbon nanotubes to be tested, the active material, and the binder in the carbon nanotube bulk resistivity test diaphragm, the carbon nanotubes to be tested, the active material, and the binder in the formed carbon nanotube bulk resistivity test diaphragm can be distributed evenly and stably, thereby improving the accuracy of the test results.

[0051] In one embodiment, the carbon nanotubes to be tested are applied to the negative electrode of the battery, and the active material is a negative electrode active material.

[0052] It can be understood that the carbon nanotubes applied to the negative electrode of the battery have specific characteristics. Mixing them with the negative electrode active material can better enable the carbon nanotubes to exert their conductivity, thereby improving the accuracy of the measured bulk resistivity of the carbon nanotubes to be tested.

[0053] In one embodiment, the negative electrode active material includes one or more of graphite and silicon.

[0054] In one embodiment, the negative electrode active material includes graphite and silicon. Thus, due to the different particle sizes of graphite and silicon, the voids between the carbon nanotubes to be tested can be better filled, making the prepared carbon nanotube bulk resistivity test diaphragm more compact, thereby improving the accuracy of the test results.

[0055] In one embodiment, the mass ratio of the graphite to the silicon is (30 - 60):(30 - 60), and for example, it can be 30:30, 30:40, 30:50, 30:60, 40:30, 40:40, 40:50, 40:60, 50:30, 50:40, 50:50, 50:60, 60:30, 60:40, 60:50, 60:60, etc.

[0056] In one embodiment, the active material is a negative electrode active material, and the binder includes one or more of styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), and polytetrafluoroethylene (PTFE). Thus, the carbon nanotubes to be tested, the active material, and the binder in the formed carbon nanotube bulk resistivity test diaphragm can be distributed more stably, thereby improving the accuracy of the test results.

[0057] In one embodiment, the binder includes styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC), and the mass ratio of the styrene-butadiene rubber (SBR) to the carboxymethyl cellulose (CMC) is (5-10):(0.2-0.6), for example, it can be 5:0.2, 5:0.3, 5:0.4, 5:0.5, 5:0.6, 6:0.2, 6:0.3, 6:0.4, 6:0.5, 6:0.6, 7:0.2, 7:0.3, 7:0.4, 7:0.5, 7:0.6, 8:0.2, 8:0.3, 8:0.4, 8:0.5, 8:0.6, 9:0.2, 9:0.3, 9:0.4, 9:0.5, 9:0.6, 10:0.2, 10:0.3, 10:0.4, 10:0.5, 10:0.6, etc. Thus, the carbon nanotubes to be tested, the active material, and the binder in the formed resistivity test film of the carbon nanotube body can be evenly and stably distributed, thereby improving the accuracy of the test results.

[0058] In one embodiment, the carbon nanotubes to be tested are applied to the positive electrode of the battery, and the active material is the positive electrode active material.

[0059] It can be understood that the carbon nanotubes applied to the positive electrode of the battery have specific characteristics. Mixing them with the positive electrode active material can better enable the carbon nanotubes to exert their conductivity, thereby improving the accuracy of the measured bulk resistivity of the carbon nanotubes to be tested.

[0060] In one embodiment, the positive electrode active material includes one or more of metal oxides, polyanion salts, fluorides, sulfides, and selenides.

[0061] As an example, the metal oxides include layered structure metal oxides and spinel-type metal oxides. The layered structure metal oxides include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), nickel cobalt manganese ternary material (LiNi x Co y Mn 1-x-y O2), lithium nickel cobalt aluminum oxide (LiNi 0.8 Co 0.15 Al 0.05 O2), lithium-rich manganese-based (xLi2MnO3(1-x)LiMO2), and the spinel-type metal oxides include lithium manganese oxide (LiMn2O4), lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4), iron tetroxide (Fe3O4), and lithium vanadate (Li x V2O4).

[0062] As an example, the polyanion salts include lithium iron phosphate (LiFePO4), lithium manganese phosphate (LiMnPO4), lithium manganese iron phosphate (LiMnx Fe 1-x PO4), lithium vanadium phosphate (Li3V2(PO4)3), lithium vanadium oxyphosphate (LiVOPO4), lithium cobalt phosphate (LiCoPO4), lithium nickel phosphate (LiNiPO4), lithium iron silicate (Li2FeSiO4), lithium iron fluorosulfate (LiFeSO4F), lithium iron borate (LiFeBO3) and lithium iron titanate (Li2FeTiO4).

[0063] In one embodiment, the active material is a positive electrode active material, and the binder includes polyvinylidene fluoride (PVDF).

[0064] In one embodiment, the mass percentage content of the polyvinylidene fluoride (PVDF) in the carbon nanotube body resistivity test film is 5% - 10%, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0065] In one embodiment, the active material is a positive electrode active material, and the carbon nanotube body resistivity test film further includes conductive carbon black (SP). Thus, the conductive carbon black can fill the gaps in the carbon nanotube body resistivity test film, thereby improving the stability of the carbon nanotube body resistivity test film, and further improving the stability of the carbon nanotube body resistivity test results.

[0066] In one embodiment, the mass percentage content of the conductive carbon black (SP) in the carbon nanotube body resistivity test film is 10% - 15%, for example, it can be 10%, 11%, 12%, 13%, 14%, 15%, etc.

[0067] It can be understood that by controlling the contents of the carbon nanotubes to be tested, the positive electrode active material, polyvinylidene fluoride, and conductive carbon black in the carbon nanotube body resistivity test film, the carbon nanotubes to be tested, the positive electrode active material, polyvinylidene fluoride, and conductive carbon black in the formed carbon nanotube body resistivity test film can be distributed evenly and stably, thereby improving the accuracy of the test results.

[0068] In a second aspect, an embodiment of the present invention provides a method for preparing a carbon nanotube body resistivity test film, including:

[0069] Providing carbon nanotubes to be tested, an active material and a binder, mixing them and then performing a film-forming treatment to obtain a carbon nanotube body resistivity test film.

[0070] In one embodiment, the mixing includes: mixing the carbon nanotubes, the active material and the binder in a solvent to obtain a slurry.

[0071] In one embodiment, the solid content of the slurry is 23% to 25%, for example, it can be 23%, 23.2%, 23.5%, 23.57%, 24%, 24.2%, 24.5%, 24.7%, 25%, etc. Thus, it is beneficial to form a uniform and stable film sheet.

[0072] In one embodiment, the film-forming treatment includes: disposing the slurry on an insulating film to form a wet film layer, and then drying the wet film layer.

[0073] In one embodiment, the material of the insulating film includes polyethylene terephthalate (PET).

[0074] It can be understood that the PET insulating film has good stability and insulation properties, which can reduce the influence on the measured results of the volume resistivity of the carbon nanotube body resistivity test film sheet, and can carry the carbon nanotube body resistivity test film sheet at the same time.

[0075] In one embodiment, the active material is a negative electrode active material and the solvent is water.

[0076] In one embodiment, the active material is a negative electrode active material, the drying temperature is 83°C - 87°C, for example, it can be 83°C, 84°C, 85°C, 86°C, 87°C, etc., and the drying time does not exceed 2h, for example, it can be 0.5h, 0.7h, 1.0h, 1.2h, 1.5h, 1.8h, 2.0h, etc.

[0077] In one embodiment, the active material is a positive electrode active material and the solvent is N-methylpyrrolidone (NMP).

[0078] In one embodiment, the active material is a positive electrode active material, the drying temperature is 102°C - 108°C, for example, it can be 102°C, 103°C, 104°C, 105°C, 106°C, 107°C, 108°C, etc., and the drying time does not exceed 2h, for example, it can be 0.5h, 0.7h, 1.0h, 1.2h, 1.5h, 1.8h, 2.0h, etc.

[0079] In one embodiment, after the film-forming treatment, it further includes cutting the formed carbon nanotube body resistivity test film into circular pieces.

[0080] In a third aspect, an embodiment of the present invention provides a method for testing the volume resistivity of a carbon nanotube body, including:

[0081] Providing the above-mentioned carbon nanotube body resistivity test film sheet, testing the volume resistivity of the carbon nanotube body resistivity test film sheet, and obtaining the volume resistivity of the film sheet;

[0082] Based on the bulk resistivity of the diaphragm, the bulk resistivity of the active material, and the bulk resistivity of the binder, the bulk resistivity of the carbon nanotubes to be tested is obtained.

[0083] In one embodiment, there are multiple carbon nanotube bulk resistivity test diaphragms. The diameter of each carbon nanotube bulk resistivity test diaphragm is 10 mm to 20 mm, for example, it can be 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, etc. The mass difference between every two carbon nanotube bulk resistivity test diaphragms is ≤0.8%, and the thickness difference between every two carbon nanotube bulk resistivity test diaphragms is ≤0.8%. In this way, the differences between multiple carbon nanotube bulk resistivity test diaphragms can be better controlled, making the carbon nanotube bulk resistivity test diaphragms used in multiple tests have consistency.

[0084] It can be understood that by repeatedly verifying multiple carbon nanotube bulk resistivity test diaphragms, the stability of the test results can be judged. If the test results of multiple carbon nanotube bulk resistivity test diaphragms are the same or have small differences, it indicates that the stability of the test results is high, thereby improving the accuracy of the test results.

[0085] In one embodiment, the method for testing the bulk resistivity of the carbon nanotube bulk resistivity test diaphragm is the four-probe resistivity test method. In this way, the accuracy of the test results can be improved.

[0086] It can be understood that the four-probe resistivity test method uses four equally spaced probes arranged vertically in a row, and at the same time applies appropriate pressure to press on the surface of the diaphragm to form an ohmic contact. A constant current source is used to pass a small current through two outer probes, and then a high-input impedance precision voltmeter is used to measure the voltage drop on two middle probes, thereby obtaining the bulk resistivity of the diaphragm. This test method can reduce the influence of wire and contact resistance on the measurement results, thereby improving the accuracy of the measurement results. It has good repeatability, simple operation, wide application range, and will not damage the thin film, which is beneficial to subsequent experiments and applications.

[0087] The following is illustrated with specific embodiments.

[0088] Example 1

[0089] This example provides a carbon nanotube bulk resistivity test diaphragm. The preparation method of the carbon nanotube bulk resistivity test diaphragm includes:

[0090] Mix the carbon nanotubes to be tested (negative electrode carbon nanotubes), SBR, graphite, silicon, and CMC with a mass ratio of 0.01:7.6:46:46:0.39 in water and stir to obtain a slurry with a solid content of 24%. Coating the slurry on a PET insulating film, and then drying it at 85°C for 1 h to form a 100-μm-thick film. Then, cut the film and the PET insulating film into round pieces with a diameter of 21 mm to obtain a carbon nanotube bulk resistivity test film loaded on the PET insulating film.

[0091] Test Example 1

[0092] Perform carbon nanotube bulk resistivity testing on the carbon nanotube bulk resistivity test film provided in Example 1. The specific testing method includes:

[0093] Take 3 carbon nanotube bulk resistivity test films loaded on the PET insulating film (the mass difference between the films ≤ 0.8%, and the thickness difference between the films ≤ 0.8%). Respectively use a four-probe resistivity tester to test the bulk resistivity of the carbon nanotube bulk resistivity test film, and obtain the bulk resistivity as shown in Table 1.

[0094] Example 2

[0095] This example is basically the same as Example 1, except that the thickness of the carbon nanotube bulk resistivity test film in this example is 150 μm.

[0096] Test Example 2

[0097] This test example is basically the same as Test Example 1, except that the carbon nanotube bulk resistivity test film used in this test example is the carbon nanotube bulk resistivity test film obtained in Example 2, and the test results are shown in Table 1.

[0098] Example 3

[0099] This example is basically the same as Example 1, except that the thickness of the carbon nanotube bulk resistivity test film in this example is 200 μm.

[0100] Test Example 3

[0101] This test example is basically the same as Test Example 1, except that the carbon nanotube bulk resistivity test film used in this test example is the carbon nanotube bulk resistivity test film obtained in Example 3, and the test results are shown in Table 1.

[0102] Example 4

[0103] This example is basically the same as Example 1, except that the mass ratio of the carbon nanotubes to be tested, SBR, graphite, silicon, and CMC in this example is 0.05:7.6:46:46:0.35.

[0104] Test Example 4

[0105] This test example is basically the same as Test Example 1, except that the carbon nanotube bulk resistivity test film used in this test example is the carbon nanotube bulk resistivity test film obtained in Example 4, and the test results are shown in Table 1.

[0106] Example 5

[0107] This example is basically the same as Example 1, except that in this example, the mass ratio of the carbon nanotubes to be tested, SBR, graphite, silicon, and CMC is 0.1:7.6:46:46:0.3.

[0108] Test Example 5

[0109] This test example is basically the same as Test Example 1, except that the carbon nanotube bulk resistivity test film used in this test example is the carbon nanotube bulk resistivity test film obtained in Example 5, and the test results are shown in Table 1.

[0110] Example 6

[0111] This example is basically the same as Example 1, except that in this example, the mass ratio of the carbon nanotubes to be tested, SBR, graphite, silicon, and CMC is 0.01:5:48.6:46:0.39.

[0112] Test Example 6

[0113] This test example is basically the same as Test Example 1, except that the carbon nanotube bulk resistivity test film used in this test example is the carbon nanotube bulk resistivity test film obtained in Example 6, and the test results are shown in Table 1.

[0114] Example 7

[0115] This example is basically the same as Example 1, except that in this example, the mass ratio of the carbon nanotubes to be tested, SBR, graphite, silicon, and CMC is 0.01:10:43.6:46:0.39.

[0116] Test Example 7

[0117] This test example is basically the same as Test Example 1, except that the carbon nanotube bulk resistivity test film used in this test example is the carbon nanotube bulk resistivity test film obtained in Example 7, and the test results are shown in Table 1.

[0118] Example 8

[0119] This example is basically the same as Example 1, except that in this example, the mass ratio of the carbon nanotubes to be tested, SBR, graphite, silicon, and CMC is 0.01:7.6:32:60:0.39.

[0120] Test Example 8

[0121] This test example is basically the same as Test Example 1, except that the carbon nanotube bulk resistivity test film used in this test example is the carbon nanotube bulk resistivity test film obtained in Example 8, and the test results are shown in Table 1.

[0122] Example 9

[0123] This example is basically the same as Example 1, except that in this example, the mass ratio of the carbon nanotubes to be tested, SBR, graphite, silicon, and CMC is 0.01:7.6:60:32:0.39.

[0124] Test Example 9

[0125] This test example is basically the same as Test Example 1, except that the carbon nanotube bulk resistivity test film used in this test example is the carbon nanotube bulk resistivity test film obtained in Example 9, and the test results are shown in Table 1.

[0126] Example 10

[0127] This example is basically the same as Example 1, except that in this example, the mass ratio of the carbon nanotubes to be tested, SBR, graphite, silicon, and CMC is 0.01:7.79:46:46:0.2.

[0128] Test Example 10

[0129] This test example is basically the same as Test Example 1, except that the carbon nanotube bulk resistivity test film used in this test example is the carbon nanotube bulk resistivity test film obtained in Example 10, and the test results are shown in Table 1.

[0130] Example 11

[0131] This example is basically the same as Example 1, except that in this example, the mass ratio of the carbon nanotubes to be tested, SBR, graphite, silicon, and CMC is 0.01:7.39:46:46:0.6.

[0132] Test Example 11

[0133] This test example is basically the same as Test Example 1, except that the carbon nanotube bulk resistivity test film used in this test example is the carbon nanotube bulk resistivity test film obtained in Example 11, and the test results are shown in Table 1.

[0134] Example 12

[0135] A carbon nanotube bulk resistivity test film and its preparation method, including:

[0136] Mix the carbon nanotubes to be tested (positive electrode carbon nanotubes), PVDF, lithium iron phosphate, and SP with a mass ratio of 0.01:7.25:80.5:12.24 in NMP and stir to obtain a slurry with a solid content of 24%. Coat the slurry on a PET insulating film and then dry it at 105°C for 1 h to form a film with a thickness of 100 - 200 μm. Then cut the film and the PET insulating film into circular pieces with a diameter of 21 mm to obtain a carbon nanotube bulk resistivity test film loaded on the PET insulating film.

[0137] Test Example 12

[0138] This test example is basically the same as Test Example 1, except that the carbon nanotube bulk resistivity test film used in this test example is the carbon nanotube bulk resistivity test film obtained in Example 12. The test results are shown in Table 2.

[0139] Example 13

[0140] This example is basically the same as Example 12, except that the mass ratio of the carbon nanotubes to be tested, PVDF, lithium iron phosphate, and SP in this example is 0.05:7.25:80.1:12.24.

[0141] Test Example 13

[0142] This test example is basically the same as Test Example 1, except that the carbon nanotube bulk resistivity test film used in this test example is the carbon nanotube bulk resistivity test film obtained in Example 13. The test results are shown in Table 2.

[0143] Example 14

[0144] This example is basically the same as Example 12, except that the mass ratio of the carbon nanotubes to be tested, PVDF, lithium iron phosphate, and SP in this example is 0.1:7.2:80.5:12.2.

[0145] Test Example 14

[0146] This test example is basically the same as Test Example 1, except that the carbon nanotube bulk resistivity test film used in this test example is the carbon nanotube bulk resistivity test film obtained in Example 14. The test results are shown in Table 2.

[0147] It should be noted that the positive electrode carbon nanotubes and the negative electrode carbon nanotubes are two different types of carbon nanotubes.

[0148] Table 1

[0149]

[0150] Table 2

[0151]

[0152] As can be seen from Table 1 and Table 2, the volume resistivity of the negative electrode carbon nanotubes measured in Examples 1-11 is very close, and the volume resistivity of the positive electrode carbon nanotubes measured in Examples 12-14 is very close. It can be seen that the carbon nanotube volume resistivity test diaphragm provided by the present application can improve the test accuracy of the volume resistivity of the carbon nanotubes to be tested obtained by measuring the volume resistivity through the test diaphragm.

[0153] The embodiments of the present invention have been introduced in detail above. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those skilled in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A carbon nanotube resistivity test film, characterized in that: Includes carbon nanotubes to be tested, active materials and binders.

2. The carbon nanotube resistivity test film according to claim 1, characterized in that: The thickness of the carbon nanotube resistivity test film is 100 μm to 200 μm; and / or The carbon nanotube resistivity test film is a disc; and / or The mass percentage of the carbon nanotubes to be tested in the carbon nanotube resistivity test film is 0.01% to 0.1%; and / or The mass percentage of the active material in the carbon nanotube resistivity test film is 60% to 95%; and / or The mass percentage of the binder in the carbon nanotube resistivity test film is 5%-10.6%.

3. The carbon nanotube resistivity test film according to claim 1, wherein: The carbon nanotubes to be tested are applied to the negative electrode of the battery, and the active material is a negative electrode active material; The carbon nanotubes to be tested are applied to the positive electrode of a battery, and the active material is a positive electrode active material.

4. The carbon nanotube resistivity test film according to claim 3, characterized in that: The negative electrode active material includes one or more of graphite and silicon; and / or The active material is a negative electrode active material, and the binder includes one or more of styrene-butadiene rubber, carboxymethyl cellulose, polyacrylic acid and polytetrafluoroethylene.

5. The carbon nanotube resistivity test film according to claim 4, characterized in that: The negative electrode active material comprises graphite and silicon, and the mass ratio of the graphite to the silicon is (30-60): (30-60); and / or The active material is a negative electrode active material, the binder comprises styrene-butadiene rubber and carboxymethyl cellulose, and the mass ratio of the styrene-butadiene rubber to the carboxymethyl cellulose is (5-10): (0.2-0.6).

6. The carbon nanotube resistivity test film according to claim 3, characterized in that: The positive electrode active material includes one or more of metal oxides, polyanion salts, fluorides, sulfides and selenides; and / or The active material is a positive electrode active material, the binder includes polyvinylidene fluoride, and the mass percentage of the polyvinylidene fluoride in the carbon nanotube resistivity test film is 5% to 10%; and / or The active material is a positive electrode active material. The carbon nanotube resistivity test film also includes conductive carbon black. The mass percentage of the conductive carbon black in the carbon nanotube resistivity test film is 10% to 15%.

7. A method for preparing a carbon nanotube resistivity test film, characterized in that: include: Providing carbon nanotubes to be tested, active materials and a binder, mixing them and then performing film forming treatment to obtain a carbon nanotube body resistivity test film.

8. The method for preparing a carbon nanotube resistivity test film according to claim 7, wherein: The mixing comprises: mixing the carbon nanotubes, active material and binder in a solvent to obtain a slurry; The film forming process includes: placing the slurry on the insulating film to form a wet film layer, and drying the wet film layer.

9. The method for preparing a carbon nanotube resistivity test film according to claim 8, wherein: The solid content of the slurry is 23% to 25%; and / or The material of the insulating film includes polyethylene terephthalate; and / or The active material is a negative electrode active material, and the solvent is water; and / or The active material is a negative electrode active material, the drying temperature is 83° C.-87° C., and the drying time is no more than 2 hours; and / or The active material is a positive electrode active material, and the solvent is N-methylpyrrolidone; and / or The active material is a positive electrode active material, the drying temperature is 102° C.-108° C., and the drying time is no more than 2 hours.

10. A method for testing the resistivity of carbon nanotubes, characterized in that: include: Providing a carbon nanotube bulk resistivity test membrane according to any one of claims 1 to 6 or a carbon nanotube bulk resistivity test membrane prepared by the preparation method of a carbon nanotube bulk resistivity test membrane according to any one of claims 7 to 9, and testing the bulk resistivity of the carbon nanotube bulk resistivity test membrane to obtain the bulk resistivity of the membrane; The volume resistivity of the carbon nanotube to be tested is obtained based on the volume resistivity of the membrane, the volume resistivity of the active material, and the volume resistivity of the binder.

11. The carbon nanotube resistivity testing method according to claim 10, wherein: There are multiple carbon nanotube resistivity test films, each of which has a diameter of 10 mm to 20 mm, a mass difference of ≤0.8% between two carbon nanotube resistivity test films, and a thickness difference of ≤0.8% between two carbon nanotube resistivity test films; and / or The method for testing the volume resistivity of the carbon nanotube volume resistivity test film is a four-probe resistivity test method.

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