Conductive paste, preparation method and application thereof

Abstract

The application discloses a conductive paste and a preparation method and application thereof, and the conductive paste comprises modified butyronitrile rubber, N-methyl pyrrolidone and carbon nanotubes; the aspect ratio of the carbon nanotubes is 130-200; and the structural formula of the modified butyronitrile rubber is: wherein the value range of n is 500-1500, and the value range of m is 200-1000. The modified butyronitrile rubber is used as a dispersant, the nitrile group in the modified butyronitrile rubber can link the carboxyl functional groups on the surface of the carbon nanotubes, the carbon nanotubes are limited from winding and agglomerating in an electrostatic stabilization and space blocking filling mode, the alkyl hydrogen chain is fused into the N-methyl pyrrolidone solvent as a solvation chain, and the combination of the two can promote the wetting of the solvent to the carbon nanotube powder in the early stage of dispersion, thereby improving the dispersion efficiency, avoiding the influence of a dispersant, a viscosity reducer and repeated grinding and other processes in the prior art on the conductive paste, and achieving the effect of improving the performance of a lithium battery.

Description

Technical Field

[0001] This invention relates to the field of conductive materials, and more particularly to a conductive paste, its preparation method, and its application. Background Technology

[0002] With the development of new energy technologies, lithium-ion batteries, as highly efficient energy storage devices, have been widely used in electric vehicles and portable electronic devices. Carbon nanotubes (CNTs) have become an ideal choice for improving the conductivity of lithium battery cathode materials due to their excellent conductivity. However, the high specific surface area and strong van der Waals forces of carbon nanotubes make their dispersion in slurries difficult. To ensure uniform dispersion of carbon nanotubes, dispersants and alkanolamine viscosity reducers are usually added to the formulation, and repeated grinding is performed.

[0003] However, amine-based viscosity reducers generate free hydroxyl groups during use, which can react with polyvinylidene fluoride in the battery cathode slurry, leading to problems such as excessively rapid slurry re-adhesion and reduced electrode adhesion, thus affecting battery performance and lifespan. Repeated grinding reduces the aspect ratio of carbon nanotubes and causes severe particle pulverization, preventing them from fully utilizing their two-dimensional chain advantages and damaging the cycle performance of lithium batteries. Furthermore, while polyvinylpyrrolidone dispersants commonly used in existing technologies can improve the dispersibility of carbon nanotubes, they are prone to oxidation reactions in 4.2V battery cells, leading to an increase in the SEI film thickness of lithium batteries, which in turn causes increased capacity decay and thickness expansion. Summary of the Invention

[0004] This invention provides a conductive paste, its preparation method, and its application to improve the performance of lithium batteries.

[0005] Specifically, the present invention provides a conductive paste comprising modified nitrile rubber, N-methylpyrrolidone, and carbon nanotubes; wherein the aspect ratio of the carbon nanotubes is 130-200; and the structural formula of the modified nitrile rubber is:

[0006] ;

[0007] Where n ranges from 500 to 1500; and m ranges from 200 to 1000.

[0008] Optionally, the carbon nanotubes account for 2%-4% of the mass percentage in the conductive slurry, and the modified nitrile rubber accounts for 0.5%-1% of the mass percentage in the conductive slurry.

[0009] This invention also provides a method for preparing a conductive paste, comprising the following steps:

[0010] Modified nitrile rubber was added to N-methylpyrrolidone; after the modified nitrile rubber was fully dissolved, carbon nanotubes were added and stirred evenly to obtain the first slurry;

[0011] The first slurry is coarsely ground until the carbon nanotubes are D 50 The particle size is reduced to 20-30 mm to obtain the second slurry;

[0012] The second slurry is finely ground to obtain the conductive slurry.

[0013] Optionally, the dissolution time of the modified nitrile rubber is 20-30 minutes.

[0014] And / or, the stirring is carried out in a premixing vessel for 15-20 minutes at a speed of 700-900 r / min.

[0015] Optionally, the coarse grinding is carried out in a sand mill, wherein the diameter of the grinding beads in the sand mill is 3-5 mm.

[0016] Optionally, the feed diaphragm pump of the sand mill has an air pressure of 0.2-0.24 MPa and a pump speed of 18-22 times / min;

[0017] And / or, the rotational speed of the sand mill is 900-1000 r / min, and the chamber pressure of the sand mill is 1.4-1.6 MPa.

[0018] Optionally, the fine grinding is carried out in a sand mill, wherein the diameter of the abrasive beads in the sand mill is 0.5-1mm.

[0019] Optionally, the feed diaphragm pump of the sand mill has an air pressure of 0.15-0.2MPa and a pump speed of 15-18 times / min;

[0020] And / or, the rotational speed of the sand mill is 1000-1200 r / min, and the chamber pressure of the sand mill is 1.4-1.6 MPa.

[0021] The present invention also provides a positive electrode slurry, comprising a positive electrode active material, and a conductive slurry as described in any one of the above claims or a conductive slurry prepared by any one of the above claims.

[0022] The present invention also provides a battery including a positive electrode sheet, the positive electrode sheet including a positive electrode active material layer, the positive electrode active material layer being formed by coating the above-mentioned positive electrode slurry.

[0023] Optionally, the positive electrode active material accounts for 97%-99% of the mass of the positive electrode active material layer;

[0024] The carbon nanotubes account for 0.02%-0.5% of the mass of the positive electrode active material layer.

[0025] Optionally, the positive electrode active material includes at least one of lithium cobalt oxide and lithium nickel cobalt manganese oxide; the single-sided compaction density of the positive electrode sheet is 3.2 g / cc-4.55 g / cc.

[0026] The beneficial effects of this invention are as follows:

[0027] This invention uses modified nitrile rubber as a dispersant. The nitrile groups in the modified nitrile rubber act as anchoring groups, which can link the carboxyl functional groups on the surface of carbon nanotubes. This restricts the entanglement and aggregation of carbon nanotubes through electrostatic stability and steric hindrance filling. The alkane-hydrogen chain acts as a solvation chain and is incorporated into the N-methylpyrrolidone solvent. The combination of the two can promote the wetting of carbon nanotube powder by the solvent in the early stage of dispersion, thereby improving the dispersion efficiency. This avoids the influence of dispersants, viscosity reducers and repeated grinding processes on conductive slurries in the prior art, thus achieving the effect of improving the performance of lithium batteries.

[0028] Furthermore, compared to ordinary nitrile rubber, modified nitrile rubber has a nitrile group on each monomer unit, which can improve the wetting effect of solvents on carbon nanotube powders and further improve dispersion efficiency. In addition, hydrogenated nitrile rubber (H-NBR) has extremely strong adhesion and solvation effect, while the large π bond on the double CN triple bond of modified nitrile rubber has a conjugated affinity with the carbon ring, which can significantly reduce the peak viscosity during the dispersion process of the cathode slurry. Therefore, the amount of modified nitrile rubber added can be greatly reduced to 0.5%-1%. Moreover, compared with hydrogenated nitrile rubber (H-NBR), modified nitrile rubber has good resistance to electro-oxidation, better structural stability, and significantly improved flexibility. Therefore, it can improve the degree of particle slippage during electrode rolling, thereby increasing the compaction density. Detailed Implementation

[0029] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] Unless otherwise specified, the raw materials, reagents and equipment involved in the embodiments of this invention can all be obtained through commercial means.

[0031] This invention also provides a conductive paste comprising modified nitrile rubber, N-methylpyrrolidone, and carbon nanotubes; wherein the aspect ratio of the carbon nanotubes is 130-200; and the structural formula of the modified nitrile rubber is:

[0032] ;

[0033] Where n ranges from 500 to 1500; and m ranges from 200 to 1000.

[0034] This invention uses modified nitrile rubber as a dispersant. The nitrile groups in the modified nitrile rubber act as anchoring groups, which can link the carboxyl functional groups on the surface of carbon nanotubes. This restricts the entanglement and aggregation of carbon nanotubes through electrostatic stability and steric hindrance filling. The alkane-hydrogen chain acts as a solvation chain and is incorporated into the N-methylpyrrolidone solvent. The combination of the two can promote the wetting of carbon nanotube powder by the solvent in the early stage of dispersion, thereby improving the dispersion efficiency. This avoids the influence of dispersants, viscosity reducers and repeated grinding processes on conductive slurries in the prior art, thus achieving the effect of improving the performance of lithium batteries.

[0035] Compared to ordinary modified nitrile rubber (NBR), modified NBR has a nitrile group on each monomer unit, which can improve the wetting effect of solvents on carbon nanotube powders and further improve dispersion efficiency. Furthermore, while hydrogenated nitrile rubber (H-NBR) has extremely strong adhesion and solvation effects, the large π bond on the double CN triple bond of modified NBR has a conjugated affinity with the carbon ring, which can significantly reduce the peak viscosity during the dispersion of the cathode slurry. Therefore, the amount of modified NBR added can be significantly reduced to 0.5%-1%. Moreover, compared to hydrogenated nitrile rubber (H-NBR), modified NBR has better resistance to electro-oxidation, better structural stability, and significantly improved flexibility. Therefore, it can improve particle slippage during electrode rolling, thereby increasing compaction density.

[0036] In one embodiment of the present invention, the carbon nanotubes account for 2%-4% of the conductive slurry by mass percentage, and the dispersant accounts for 0.5%-1% of the conductive slurry. The aspect ratio of the carbon nanotubes is 130-200. By using modified nitrile rubber as a dispersant and combining it with the above-mentioned dispersion process, the aspect ratio of the carbon nanotubes can be increased from 60-90 in the original formulation to 130-200, thereby improving the effective utilization rate of carbon nanotubes. This reduces the amount of carbon nanotubes added by 20%-40%, which not only reduces costs but also lightens the weight of the final product.

[0037] This invention also provides a method for preparing a conductive paste, comprising the following steps:

[0038] Modified nitrile rubber was added to N-methylpyrrolidone; after the modified nitrile rubber was fully dissolved, carbon nanotubes were added and stirred evenly to obtain the first slurry;

[0039] The first slurry is coarsely ground until the carbon nanotubes are D 50 The particle size is reduced to 20-30 mm to obtain the second slurry;

[0040] The second slurry is finely ground to obtain the conductive slurry.

[0041] Specifically, the dissolution time is 20-30 minutes. The stirring is carried out in a premixing tank for 15-20 minutes at a speed of 800 rpm.

[0042] The coarse grinding is carried out in a sand mill, where the diameter of the grinding balls is 3-5 mm. The feed diaphragm pump of the sand mill has an air pressure of 0.2-0.24 MPa and a pump speed of 18-22 times / min; the rotational speed of the sand mill is 900-1000 r / min, and the internal pressure of the sand mill is 1.4-1.6 MPa.

[0043] The fine grinding is carried out in a sand mill, where the diameter of the grinding beads is 0.5-1mm.

[0044] The feed diaphragm pump of the sand mill has an air pressure of 0.15-0.2MPa and a pump speed of 15-18 times / min; the rotation speed of the sand mill is 1000-1200r / min; and the chamber pressure of the sand mill is 1.4-1.6MPa.

[0045] By using modified nitrile rubber as a dispersant and combining it with the above-mentioned dispersion process, dispersion time can be reduced and production efficiency can be improved. At the same time, the length of carbon nanotubes can be preserved, and the proportion of carbon nanotubes that are broken and pulverized due to excessive grinding can be reduced. The aspect ratio of carbon nanotubes can be increased from 15-80 in the original formula to 130-200, thereby improving the effective utilization rate of carbon nanotubes. This results in better conductivity at the same amount of addition, and the amount of carbon nanotubes added can be reduced (by 20%-40%) without affecting the conductivity. Therefore, during battery cycling, side reactions caused by high conductivity specific surface area can be reduced, and the rate of increase in internal resistance can be effectively reduced.

[0046] Meanwhile, using this conductive paste in the LCO / NCM series formulations for the positive electrode can significantly increase the compaction density of the positive electrode sheet, thereby improving the volumetric energy density of the cell. Furthermore, a larger aspect ratio can reduce the rate of increase in internal resistance of the cell, mitigating performance degradation issues such as high-temperature gas generation caused by increased internal resistance. In addition, the modified nitrile rubber is stable and can maintain structural stability at higher voltages, thus improving the stability of the electrode paste, reducing the risk of positive electrode paste sedimentation, improving the coating and processing window, reducing areal density fluctuations, improving cell consistency, and further improving and optimizing cell cycle performance.

[0047] The present invention also provides a positive electrode paste, comprising any of the conductive pastes described above, to possess all the effects of a conductive paste.

[0048] The present invention also provides a battery including a positive electrode sheet, the positive electrode sheet including a positive electrode active material layer, the positive electrode active material layer being formed by coating the above-mentioned positive electrode slurry to have all the effects of the conductive slurry.

[0049] Specifically, the positive electrode active material accounts for 97%-99% of the mass of the positive electrode active material layer; the carbon nanotubes account for 0.02%-0.5% of the mass of the positive electrode active material layer. The positive electrode active material includes at least one of lithium cobalt oxide and lithium nickel cobalt manganese oxide; the single-sided compaction density of the positive electrode sheet is 3.2 g / cc-4.55 g / cc. When the positive electrode active material is lithium cobalt oxide, the single-sided compaction density of the positive electrode sheet is 4.05 g / cc-4.55 g / cc; when the positive electrode active material is lithium nickel cobalt manganese oxide, the single-sided compaction density of the positive electrode sheet is 3.2 g / cc-3.8%.

[0050] The present invention will be further described below through specific embodiments.

[0051] Example 1

[0052] Carbon nanotubes, modified nitrile butadiene rubber (NBR), and N-methylpyrrolidone (NMR) were weighed according to a ratio of 3:0.8:96.2. The weighed NBR was added to the NMR solvent and stirred in a premixing vessel for 25 minutes to dissolve. Then, carbon nanotube powder was added, and the mixture was stirred at 800 rpm for 20 minutes to obtain the first slurry. The structural formula of the modified NBR is as follows:

[0053] .

[0054] The first slurry is transferred to a horizontal sand mill using 3-5mm abrasive beads. The feed diaphragm pump is controlled at an air pressure of 0.22MPa, a pump speed of 20 times / min, a horizontal sand mill speed of 950r / min, and a chamber pressure of 1.5MPa. The mill is then subjected to inverted grinding until the D50 particle size of the carbon nanotubes is reduced to 20-30mm, thus obtaining the second slurry.

[0055] The second slurry was transferred to a horizontal sand mill using 0.5-1mm abrasive beads. The feed diaphragm pump was controlled at an air pressure of 0.18MPa, a pump speed of 16 times / min, a chamber pressure of 1.5MPa, and a horizontal sand mill speed of 1100r / min for fine grinding for 450min to obtain a conductive slurry.

[0056] The above-mentioned conductive paste was used in the active layer of the positive electrode to prepare a lithium battery.

[0057] Example 2

[0058] The difference between this embodiment and Example 1 is that the ratio of carbon nanotubes, modified nitrile rubber, and N-methylpyrrolidone is 1:0.8:98.2.

[0059] Example 3

[0060] The difference between this embodiment and Embodiment 1 is that the ratio of carbon nanotubes, modified nitrile rubber, and N-methylpyrrolidone is 2:0.8:97.2.

[0061] Example 4

[0062] The difference between this embodiment and Embodiment 1 is that the ratio of carbon nanotubes, modified nitrile rubber, and N-methylpyrrolidone is 4:0.8:95.2.

[0063] Example 5

[0064] The difference between this embodiment and Example 1 is that the ratio of carbon nanotubes, modified nitrile rubber, and N-methylpyrrolidone is 6:0.8:93.2.

[0065] Example 6

[0066] The difference between this embodiment and Example 1 is that the ratio of carbon nanotubes, modified nitrile rubber, and N-methylpyrrolidone is 3:0.2:96.8.

[0067] Example 7

[0068] The difference between this embodiment and Embodiment 1 is that the ratio of carbon nanotubes, modified nitrile rubber, and N-methylpyrrolidone is 3:0.5:96.5.

[0069] Example 8

[0070] The difference between this embodiment and Embodiment 1 is that the ratio of carbon nanotubes, modified nitrile rubber, and N-methylpyrrolidone is 3:1:96.

[0071] Example 9

[0072] The difference between this embodiment and Embodiment 1 is that the ratio of carbon nanotubes, modified nitrile rubber, and N-methylpyrrolidone is 3:2:95.

[0073] Comparative Example 1

[0074] The difference between this comparative example and Example 1 is that the modified nitrile rubber is replaced with polyvinylpyrrolidone dispersant.

[0075] Comparative Example 2

[0076] Weigh carbon nanotubes, modified nitrile rubber, and N-methylpyrrolidone in a ratio of 3:0.8:96.2; add the weighed modified nitrile rubber to N-methylpyrrolidone solvent and stir to dissolve for 25 min in a premixing kettle; then add carbon nanotube powder and stir at 800 r / min for 20 min to obtain the first slurry.

[0077] The first slurry was transferred to a horizontal sand mill using 3-5mm abrasive beads. The air pressure of the feed diaphragm pump was controlled at 0.22MPa, the pump speed at 20 times / min, the rotation speed of the horizontal sand mill at 950r / min, and the chamber pressure at 1.5MPa. The mill was then subjected to inverted grinding for 450min to obtain a conductive slurry.

[0078] The above-mentioned conductive paste was used in the active layer of the positive electrode to prepare a lithium battery.

[0079] Comparative Example 3

[0080] Weigh carbon nanotubes, modified nitrile rubber, and N-methylpyrrolidone in a ratio of 3:0.8:96.2; add the weighed modified nitrile rubber to N-methylpyrrolidone solvent and stir to dissolve for 25 min in a premixing kettle; then add carbon nanotube powder and stir at 800 r / min for 20 min to obtain the first slurry.

[0081] The first slurry was transferred to a horizontal sand mill using 0.5-1mm abrasive beads. The feed diaphragm pump was controlled at an air pressure of 0.18MPa, a pump speed of 16 times / min, a chamber pressure of 1.5MPa, and a horizontal sand mill speed of 1100r / min for fine grinding for 450min to obtain a conductive slurry.

[0082] Comparative Example 4

[0083] The difference between this comparative example and Example 1 is that nitrile rubber is used instead of modified nitrile rubber. The structural formula of nitrile rubber is:

[0084] .

[0085] Comparative Example 5

[0086] The difference between this comparative example and Example 1 is that the modified nitrile rubber is replaced with hydrogenated nitrile rubber (H-NBR); wherein, hydrogenated nitrile rubber (H-NBR) is obtained by hydrogen substitution of a copolymer of acrylonitrile and butadiene.

[0087] The above-mentioned conductive paste was used in the active layer of the positive electrode to prepare a lithium battery.

[0088] The performance of the positive electrode slurry and lithium battery in the above embodiments and comparative examples was tested, and the test results are shown in Table 1.

[0089] Slurry stability test method: Take 500 lm of positive electrode slurry, seal and let stand for 48 hours, test the solid content, calculate the change in solid content; scrape the bottom and observe whether it settles.

[0090] Reverse viscosity numerical test method: Use a rotational viscometer to test the viscosity or a rheometer to test the rheological curve.

[0091] Cell volumetric energy density test: After the cell is manufactured, the battery thickness and actual capacity are tested, and the volumetric energy is calculated by dividing the actual capacity by the actual volume. The ratio of other embodiments and comparative examples to the benchmark is calculated using the embodiment with the highest energy density mentioned as the benchmark.

[0092] Table 1 Test Results

[0093]

[0094] The variation in solid content within ±0.5% is considered a normal testing error. The normal range for anti-viscosity values ​​is -500 mPa·s to 2000 mPa·s.

[0095] All indicators in Examples 1-4 and Examples 8-9 were normal. In Example 5, the proportion of the solvent N-methylpyrrolidone was relatively low, which had a certain impact on the solid content of the positive electrode slurry after standing.

[0096] In Examples 6 and 7, the content of modified nitrile rubber was low, which was insufficient to stably restrict the entanglement and aggregation of carbon nanotubes. Therefore, the slurry agglomerated and settled.

[0097] In Comparative Example 1, a polyvinylpyrrolidone (PVP) dispersant from the existing technology was used to replace the modified nitrile butadiene rubber (NBR). The slurry exhibited gelation. This may be because the molecular structure of PPVP contains strongly polar lactam hydrophilic groups and C-chain lipophilic groups, while the modified NBR possesses strong polarity and elasticity. This difference in chemical properties may prevent PPVP from fully replicating the bonding and stabilizing effects of the modified NBR during the substitution process, leading to instability in the slurry system.

[0098] In Comparative Example 2, the grinding was only done once, and the acorn beads were relatively large, resulting in large carbon nanotubes after grinding, which were not easy to disperse stably, thus causing sedimentation.

[0099] In Comparative Example 3, grinding was only done once, but the acorn beads were small in size, resulting in smaller carbon nanotubes. Although they could be dispersed evenly, the length of the carbon nanotubes could not be retained, reducing the effective utilization rate of the carbon nanotubes. As a result, the volumetric energy density of the battery cell decreased. At the same time, the small size of the carbon nanotubes in the positive electrode slurry made them easy to over-disperse, resulting in a high anti-adhesion value and easy gelation of the slurry, which led to fluctuations in the coating process.

[0100] Comparative Example 4 showed that replacing the modified nitrile rubber with nitrile rubber from the existing technology did not have a significant impact; this may be because the amount of nitrile rubber was sufficient, and therefore the nitrile groups contained therein were enough to improve the wetting effect of the solvent on the carbon nanotube powder.

[0101] Comparative Example 5 uses hydrogenated nitrile rubber (H-NBR) from the existing technology instead of modified nitrile rubber. Due to the strong adhesion and solvation effect of hydrogenated nitrile rubber (H-NBR), the wetting effect of the solvent on the carbon nanotube powder decreases, the carbon nanotubes are not dispersed evenly, which in turn leads to a deterioration in the conductivity of the positive electrode active material layer, a decrease in the measured actual capacity, which is manifested as a decrease in volumetric energy density.

[0102] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A conductive paste for batteries, characterized in that, It includes modified nitrile butadiene rubber, N-methylpyrrolidone, and carbon nanotubes; the aspect ratio of the carbon nanotubes is 130-200; the structural formula of the modified nitrile butadiene rubber is: ； Where n ranges from 500 to 1500; and m ranges from 200 to 1000. The carbon nanotubes account for 2%-4% of the mass percentage in the conductive slurry, and the modified nitrile rubber accounts for 0.5%-1% of the mass percentage in the conductive slurry.

2. The method for preparing the conductive paste for batteries according to claim 1, characterized in that, Includes the following steps: Modified nitrile rubber was added to N-methylpyrrolidone; After the modified nitrile rubber is dissolved, carbon nanotubes are added and stirred evenly to obtain the first slurry; The first slurry is coarsely ground until the carbon nanotubes are D 50 The particle size is reduced to 20-30 mm to obtain the second slurry; The second slurry is finely ground to obtain the conductive slurry.

3. The preparation method according to claim 2, characterized in that, The modified nitrile rubber dissolves in 20-30 minutes. And / or, the stirring is carried out in a premixing vessel for 15-20 minutes at a speed of 700-900 r / min.

4. The preparation method according to claim 2, characterized in that, The coarse grinding is carried out in a sand mill, where the diameter of the abrasive beads is 3-5 mm. And / or, the fine grinding is carried out in a sand mill, wherein the diameter of the abrasive beads in the sand mill is 0.5-1 mm.

5. The preparation method according to claim 4, characterized in that, During the coarse grinding process, the air pressure of the feed diaphragm pump of the sand mill is 0.2-0.24 MPa, and the pump speed is 18-22 times / min; And / or, the rotational speed of the sand mill is 900-1000 r / min, and the chamber pressure of the sand mill is 1.4-1.6 MPa.

6. The preparation method according to claim 4, characterized in that, During the fine grinding process, the air pressure of the feed diaphragm pump of the sand mill is 0.15-0.2MPa, and the pump speed is 15-18 times / min; And / or, the rotational speed of the sand mill is 1000-1200 r / min, and the chamber pressure of the sand mill is 1.4-1.6 MPa.

7. A positive electrode slurry, characterized in that, It includes a positive electrode active material, and a conductive paste as described in claim 1 or a conductive paste prepared by the preparation method as described in any one of claims 2-6.

8. A battery, characterized in that, It includes a positive electrode sheet, the positive electrode sheet including a positive electrode active material layer, the positive electrode active material layer being formed by coating the positive electrode slurry according to claim 7.

9. The battery according to claim 8, characterized in that, The positive electrode active material accounts for 97%-99% of the mass of the positive electrode active material layer; The carbon nanotubes account for 0.02%-0.5% of the mass of the positive electrode active material layer.

10. The battery according to claim 8, characterized in that, The positive electrode active material includes at least one of lithium cobalt oxide and lithium nickel cobalt manganese oxide; the single-sided compaction density of the positive electrode sheet is 3.2 g / cc-4.55 g / cc.

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