Positive electrode paste manufacturing method, secondary battery, battery pack, and power consumption device

Abstract

This application provides a method for manufacturing a positive electrode paste, a secondary battery, a battery pack, and a power consumption device. The method includes first, second, third, and fourth stirring steps. In the first stirring step, a positive electrode active material and a conductive agent are mixed and stirred to produce a dry mixture. In the second stirring step, a binder and a solvent are mixed and stirred to produce a binder liquid. In the third stirring step, the dry mixture and the binder liquid are mixed and stirred to produce a primary paste. In the fourth stirring step, the binder, the solvent, and the primary paste are mixed and stirred to produce a positive electrode paste. The binder and the solvent used in the second stirring step are the same as those used in the fourth stirring step. The weight percentage of the binder used in the second stirring step is 50% to 70% and the weight percentage of the binder used in the fourth stirring step is 30% to 50% of the total weight of the binder used in the second stirring step and the binder used in the fourth stirring step, respectively.

Description

[Technical Field]

[0001] The present application relates to the field of secondary battery technology, and more particularly to a method for manufacturing a positive electrode paste for a secondary battery, a secondary battery, a battery pack, and a power consumption device. [Background technology]

[0002] In recent years, as the application range of secondary batteries becomes wider and wider, secondary batteries are widely used in energy storage power supply systems such as hydroelectric power, thermal power, wind power and solar power plants, as well as in many fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment and aerospace.

[0003] Electrode paste is the basis for forming electrodes and the first step in the production of secondary batteries. The properties of the electrode paste have a significant impact on subsequent electrode production and battery performance. Positive electrode paste is a solid-liquid mixed system primarily composed of a positive electrode active material, a conductive agent, a binder, and a solvent. This system is in a metastable state, and the paste mixing process, i.e., the paste manufacturing method, has a significant impact on the paste's properties, such as dispersibility, uniformity, and stability. Conventional paste mixing processes are typically one-step processes, which directly mix and stir the components of the positive electrode active material paste. However, one-step manufacturing methods cannot meet the needs of binders with different weight-average molecular weights, making the paste mixing process less versatile and disadvantageous for reducing production costs. Therefore, there is a need to develop new paste manufacturing methods that can accommodate binders with different weight-average molecular weights. Summary of the Invention

[0004] The present application has been made in view of the above-mentioned problems, and its purpose is to provide a method for manufacturing a positive electrode paste for a secondary battery that is adaptable to binders with different weight-average molecular weights, widens the process window for coating the positive electrode paste, and improves the processability of the positive electrode paste.

[0005] To achieve the above object, the present application provides a method for producing a positive electrode paste, including first stirring, second stirring, third stirring, and fourth stirring. In the first stirring, a positive electrode active material and a conductive agent are mixed and stirred to produce a dry mixture. In the second stirring, a binder and a solvent are mixed and stirred to produce a binder liquid. In the third stirring, the dry mixture and the binder liquid are mixed and stirred to produce a primary paste. In the fourth stirring, the binder, solvent, and primary paste are mixed and stirred to produce a positive electrode paste. The binder and solvent used in the second stirring are the same as those used in the fourth stirring, respectively. The weight percentage of the binder used in the second stirring is 50% to 70% and the weight percentage of the binder used in the fourth stirring is 30% to 50% of the total weight of the binder used in the second stirring and the binder used in the fourth stirring.

[0006] As a result, the positive electrode paste manufacturing method disclosed herein has broader versatility than conventional positive electrode paste manufacturing methods and is adaptable to pastes containing binders with different weight average molecular weights. Compared to conventional manufacturing methods, the present invention performs paste mixing in separate steps, thereby reducing the viscosity of the positive electrode paste at the time of shipment and after standing for 24 hours, mitigating the gelation phenomenon of the positive electrode paste, and improving the adaptability of the manufacturing method to high molecular weight binders. This broader versatility of the manufacturing method widens the process window for applying the positive electrode paste, and improves the processability of the positive electrode paste.

[0007] In an optional embodiment, the binder includes at least polyvinylidene fluoride having a weight average molecular weight of 800,000 to 8,000,000.

[0008] The manufacturing method disclosed herein is universal for both low-molecular-weight and high-molecular-weight polyvinylidene fluoride binders, and can effectively mitigate the gelation phenomenon of different pastes, helping to improve production efficiency and widen the application process window of the paste. The manufacturing method disclosed herein can be applied to binders with a weight-average molecular weight of up to 8 million, so that pastes containing binders with high weight-average molecular weights still have low viscosity at shipping and anti-gelling properties, meeting the needs of next-generation binders.

[0009] In any embodiment, the third stirring is first performed at a low speed, and then at a high speed.

[0010] In the third stirring step, the dry mixture and binder liquid are first stirred at a low speed to ensure that the dry mixture is thoroughly dispersed in the binder liquid while avoiding excessive shearing of the dry mixture, thereby ensuring the integrity of the positive active material and the conductive agent. After the low-speed stirring, the binder liquid coats the positive active material and the conductive agent, preventing subsequent high-speed stirring from destroying the structure and dimensions of the positive active material and the conductive agent. By further stirring at a high speed after the low-speed stirring, the viscosity of the paste can be reduced while ensuring the properties of the materials.

[0011] In any embodiment, the revolution speed of the low-speed stirring in the third stirring is 15 rpm to 25 rpm, the rotation speed is 400 rpm to 800 rpm, and the stirring time is 5 minutes to 15 minutes.

[0012] By controlling the revolution speed, rotation speed, and stirring time of the high-speed stirring in the third stirring within appropriate ranges, the paste has low viscosity at the time of shipment, low viscosity after standing for 24 hours, and excellent anti-gelling properties, which are advantageous in improving the coatability, processability, and stability of the paste.

[0013] In any embodiment, the revolution speed of the high-speed stirring in the third stirring is 20 rpm to 30 rpm, the rotation speed is 1000 rpm to 1300 rpm, and the stirring time is 50 minutes to 80 minutes.

[0014] By controlling the revolution speed, rotation speed, and stirring time of the high-speed stirring in the third stirring within appropriate ranges, the paste has low viscosity at the time of shipment, low viscosity after standing for 24 hours, and excellent anti-gelling properties, which are advantageous in improving the coatability, processability, and stability of the paste.

[0015] In any embodiment, the rotation speed of the first agitation is 0.

[0016] By controlling the rotation speed of the first stirring to 0, the shear force of the first stirring can be minimized, the possibility of the positive electrode active material and the conductive agent being excessively crushed is sufficiently reduced, and the positive electrode active material and the conductive agent are guaranteed to have a certain granularity and specific surface area, which is helpful in improving the dispersion effect of the positive electrode active material and the conductive agent, reducing the viscosity of the paste after standing for 24 hours, mitigating the gelling phenomenon of the paste, and improving the stability of the paste.

[0017] In any embodiment, the revolution speed of the first stirring is 20 rpm to 30 rpm.

[0018] By controlling the revolution speed of the first stirring within an appropriate range, the paste has low viscosity at the time of shipment, low viscosity after standing for 24 hours, and anti-gelling properties, which are advantageous in improving the coatability, processability, and stability of the paste.

[0019] In any embodiment, the stirring time of the first stirring is 5 minutes to 20 minutes.

[0020] By controlling the stirring time of the first stirring within an appropriate range, the paste has low viscosity at the time of shipment, low viscosity after standing for 24 hours, and anti-gelling properties, which are advantageous in improving the coatability, processability, and stability of the paste.

[0021] In any embodiment, the stirring time of the second stirring is 50 minutes to 80 minutes.

[0022] By controlling the stirring time of the second stirring within an appropriate range, the paste has low viscosity at the time of shipment, low viscosity after standing for 24 hours, and anti-gelling properties, which are advantageous in improving the coatability, processability, and stability of the paste.

[0023] In any embodiment, the revolution speed of the second stirring is 25 rpm to 40 rpm.

[0024] By controlling the revolution speed of the second stirring within an appropriate range, the viscosity of the paste at the time of shipment and after standing for 24 hours can be kept low, which is advantageous in alleviating the gelling state of the paste, improving the stability of the paste, and widening the process window.

[0025] In any embodiment, the rotation speed of the second stirring is 1000 rpm to 1300 rpm.

[0026] By controlling the rotation speed of the second stirring within an appropriate range, the paste has low viscosity at the time of shipment, low viscosity after standing for 24 hours, and anti-gelling properties, thereby improving the coatability, processability, and stability of the paste.

[0027] In any embodiment, the stirring time of the fourth stirring is 60 minutes to 90 minutes.

[0028] By controlling the stirring time of the fourth stirring within an appropriate range, the paste has low viscosity at the time of shipment and after standing for 24 hours, which is advantageous in alleviating the gelling state of the paste, improving the paste stability, and widening the process window.

[0029] In any embodiment, the revolution speed of the fourth stirring is 25 rpm to 40 rpm.

[0030] By controlling the revolution speed of the fourth stirrer within an appropriate range, the paste has low viscosity at the time of shipment and after standing for 24 hours, which is also advantageous in mitigating the gelling state of the paste, improving the paste stability, and widening the process window.

[0031] In any embodiment, the rotation speed of the fourth stirring is 1000 rpm to 1300 rpm.

[0032] By controlling the rotation speed of the fourth stirrer within an appropriate range, the viscosity of the paste at the time of shipment and after standing for 24 hours can be kept low, which is advantageous in alleviating the gelling state of the paste, improving the paste stability, and widening the process window.

[0033] In an optional embodiment, the solid content of the positive electrode paste is 65% to 70%, and the viscosity of the positive electrode paste is 6000 to 31000 mPa·s.

[0034] The paste formed by the manufacturing method of the present invention has a high solid content, suitable viscosity, and excellent processability, and the paste can be directly used in the subsequent coating process, thereby improving production efficiency.

[0035] In any embodiment, with respect to the total mass of the positive electrode active material, the conductive agent, the binder used in the second stirring, and the binder used in the fourth stirring, the mass percentage of the solvent used in the second stirring is 35% to 45%, and the mass percentage of the solvent used in the fourth stirring is 4% to 10%.

[0036] In any embodiment, in the positive electrode paste, the ratio of the mass of the positive electrode active material, the total mass of the binder, and the mass of the conductive agent is (88 to 96):(2 to 4):(2 to 8).

[0037] A positive electrode paste within the above range not only has good processability, but also provides a positive electrode sheet after molding with excellent electrical and chemical properties.

[0038] In any embodiment, the positive electrode active material is at least one of lithium iron phosphate and modified materials thereof, and lithium nickel cobalt manganese oxide and modified materials thereof, and the modified materials are prepared by one or more of the following modification methods: doping, conductive carbon coating, conductive metal coating, and conductive polymer coating.

[0039] In any embodiment, the solvent is selected from one or more of N-methyl-2-pyrrolidone, N,N-dimethylpropionamide, N,N-diethylpropionamide, N,N-dipropylpropionamide, N,N-dibutylpropionamide, N,N-dimethylethylpropionamide, and 3-butoxy-N-methylpropionamide.

[0040] According to a second aspect of the present application, there is further provided a positive electrode paste produced by the method for producing a positive electrode paste according to the first aspect.

[0041] In an optional embodiment, the positive electrode paste has a solids content of 65% to 70%, an initial viscosity of 6000 to 31000 mPa·s, and after standing for 24 hours, the viscosity of the positive electrode paste does not exceed 49000 mPa·s.

[0042] The positive electrode paste provided by the present application has a high solid content, suitable viscosity, and excellent processability, and at the same time, the paste has excellent storage stability.

[0043] According to a third aspect of the present application, there is provided a secondary battery further comprising a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte, wherein the positive electrode sheet is manufactured from the positive electrode paste produced by the method for producing a positive electrode paste according to the first aspect or the positive electrode paste according to the second aspect. The positive electrode sheet has high quality and is produced efficiently.

[0044] In any embodiment, the secondary battery is one of a lithium ion battery, a sodium ion battery, a magnesium ion battery, and a potassium ion battery.

[0045] According to a fourth aspect of the present application, there is further provided a battery module including the secondary battery according to the third aspect of the present application.

[0046] According to a fifth aspect of the present application, there is provided a battery pack including the secondary battery according to the third aspect of the present application or the battery module according to the fourth aspect of the present application.

[0047] According to a sixth aspect of the present application, there is provided a power consumption device including at least one selected from the secondary battery according to the third aspect of the present application, the battery module according to the fourth aspect of the present application, or the battery pack according to the fifth aspect of the present application. [Brief explanation of the drawings]

[0048] [Figure 1] 1 is a schematic diagram of a secondary battery according to an embodiment of the present application; [Figure 2] FIG. 2 is an exploded view of the secondary battery shown in FIG. 1 according to the embodiment of the present application. [Figure 3] 1 is a schematic diagram of a battery module according to an embodiment of the present application; [Figure 4] 1 is a schematic diagram of a battery pack according to an embodiment of the present application. [Figure 5] FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application. [Figure 6] 1 is a schematic diagram of a power consumption device that uses a secondary battery as a power source according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0049] Hereinafter, embodiments specifically disclosing the present application's cathode active material and manufacturing method thereof, cathode sheet, secondary battery, battery module, battery pack, and power consumption device will be described in detail with appropriate reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters and redundant description of actually identical structures may be omitted. This is to avoid unnecessary lengthening of the following description and to facilitate easy understanding by those skilled in the art. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0050] The "ranges" disclosed in this application are defined in the form of lower and upper limits, and a given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Such defined ranges may be inclusive or exclusive of the end values, and are arbitrarily combinable; i.e., any lower limit can be combined with any upper limit to form a single range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if 1 and 2 are listed as minimum range values ​​and 3, 4, and 5 are listed as maximum range values, the ranges 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 are all contemplated. In this application, unless otherwise specified, a numerical range "a to b" represents a shorthand notation for any combination of real numbers a to b, where a and b are both real numbers. For example, the numerical range "0-5" indicates that this specification has already listed all real numbers between "0-5," and "0-5" is merely a shorthand representation of combinations of these numbers. Also, expressing a parameter as an integer ≧2 is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0051] Unless otherwise stated, all embodiments and optional embodiments in the present application can be combined with each other to form a new technical solution.

[0052] Unless otherwise stated, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0053] Unless otherwise specified, all steps in this application may be performed in order or randomly, and are preferably performed in order. For example, when the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, when the method mentioned above may further include step (c), it means that step (c) may be added to the method in any order, and for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0054] Unless otherwise specified, the terms "comprise" and "include" used in this application may be open-ended or closed-ended. For example, the terms "comprise" and "include" may indicate that other components not listed may be further included or included, or that only the listed components may be included or included.

[0055] Unless otherwise stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, "A or B" is satisfied when A is true (or exists) and B is false (or does not exist), when A is false (or does not exist) but B is true (or exists), or when both A and B are true (or exist).

[0056] Positive electrode paste is a solid-liquid mixture primarily composed of a positive electrode active material, a conductive agent, a binder, and a solvent. To improve the uniformity of the distribution of the different components in the system, paste mixing is typically performed using processes such as stirring, ball milling, and ultrasonication. However, conventional paste mixing processes are generally only applicable to paste systems with fixed components, resulting in limited versatility. Changes in the physical properties of the components in the paste often necessitate adjustments to the paste mixing process. For example, conventional paste mixing processes are not applicable to high-molecular-weight binders, nor are they applicable to binders with high weight-average molecular weight dispersion and poor batch production stability. Pastes using different batches of binder produced using the same conventional paste mixing process result in significant performance differences and are prone to gel formation in the paste, making it difficult to meet the production needs of polar sheets.

[0057] [Positive electrode paste manufacturing method] Based on this, the present application provides a method for manufacturing a positive electrode paste, including first stirring, second stirring, third stirring, and fourth stirring. In the first stirring, a positive electrode active material and a conductive agent are mixed and stirred to produce a dry mixture. In the second stirring, a binder and a solvent are mixed and stirred to produce a binder liquid. In the third stirring, the dry mixture and the binder liquid are mixed and stirred to produce a primary paste. In the fourth stirring, the binder, solvent, and primary paste are mixed and stirred to produce a positive electrode paste. The binder and solvent used in the second stirring are the same as those used in the fourth stirring, respectively. The weight percentage of the binder used in the second stirring is 50% to 70% and the weight percentage of the binder used in the fourth stirring is 30% to 50% of the total weight of the binder used in the second stirring and the binder used in the fourth stirring.

[0058] In some embodiments, the positive electrode active material is a lithium-containing transition metal oxide, and in some embodiments, the positive electrode active material is at least one of lithium iron phosphate and modified materials thereof, and lithium nickel cobalt manganese oxide and modified materials thereof, and the modified materials are prepared by one or more of the following modification methods: doping, conductive carbon coating, conductive metal coating, and conductive polymer coating.

[0059] In some embodiments, the conductive agent can include at least one of superconducting carbon, carbon black, carbon nanotubes, graphene, and carbon nanofibers.

[0060] In some embodiments, the solvent is an aqueous medium, such as deionized water.

[0061] In some embodiments, the solvent is an oily medium selected from one or more of N-methyl-2-pyrrolidone, N,N-dimethylpropionamide, N,N-diethylpropionamide, N,N-dipropylpropionamide, N,N-dibutylpropionamide, N,N-dimethylethylpropionamide, and 3-butoxy-N-methylpropionamide.

[0062] In this manufacturing method, the cathode active material and conductive agent are first stirred to obtain a dry mixture. The first stirring allows the two to form a tight entanglement due to the anchoring effect. The binder and solvent are then mixed and stirred to produce a binder liquid. This step effectively disperses the binder in the solvent and avoids the aggregation and solidification that would occur if the binder were directly mixed with other materials. The dry mixture of the cathode active material and conductive agent is then mixed with the binder liquid and stirred a third time to produce a primary paste. The third stirring effectively disperses the cathode active material and conductive agent in the binder liquid. The binder in the binder liquid improves the paste stability through electrostatic and steric hindrance, reducing aggregation and sedimentation of the cathode active material and conductive agent. Finally, the primary paste is mixed with a binder and a solvent and subjected to a fourth stirring to obtain a positive electrode paste. The binder added again during the fourth stirring coats the positive electrode active material and the conductive agent, thereby stably dispersing the materials in the paste and delaying the gelation of the paste. The solvent added again during the fourth stirring effectively adjusts the viscosity of the paste at the time of shipment, preventing the viscosity at the time of shipment from being too high and affecting the subsequent coating process.

[0063] With respect to the total mass of the binder used in the second mixing and the binder used in the fourth mixing, the mass percentage of the binder used in the second mixing is 50% to 70%, and the mass percentage of the binder used in the fourth mixing is 30% to 50%. If the mass of the binder added in the second mixing or the fourth mixing is too much or too little, the viscosity of the paste at the time of shipping and the viscosity after standing for 24 hours cannot be effectively reduced, and the purpose of mitigating gelation of the paste cannot be achieved.

[0064] Prior art positive electrode paste manufacturing methods had low compatibility and were unable to accommodate differences in the weight-average molecular weight of binders in the paste, resulting in high material precision requirements. The present invention uses a separate paste mixing step to reduce the viscosity of the positive electrode paste at shipment and after 24 hours of standing, thereby mitigating the gelation phenomenon of the positive electrode paste. Therefore, pastes with high weight-average molecular weight binders still have low viscosity at shipment and after 24 hours of standing, and retain anti-gelling properties, improving the versatility of the manufacturing method. The present manufacturing method is compatible with not only low weight-average molecular weight binders but also high weight-average molecular weight binders, effectively mitigating the gelation phenomenon of different pastes, improving production efficiency, and widening the paste coating process window.

[0065] As used herein, the term "process window" refers to a process range within which product quality can be guaranteed, including but not limited to temperature range, pressure range, length of storage time, etc. It can be understood that the wider the process window, the lower the requirements for process precision.

[0066] In some embodiments, the binder includes at least polyvinylidene fluoride having a weight average molecular weight of 800,000 to 8,000,000. In some embodiments, the weight average molecular weight of polyvinylidene fluoride may be selected from any one of 800,000, 1,000,000, 1.5 million, 2,000,000, 2.5 million, 3,000,000, 3.5 million, 4,000,000, 4.5 million, 5,000,000, 5.5 million, 6,000,000, 6.5 million, 7,000,000, 7.5 million, and 8,000,000.

[0067] As used herein, the term "weight average molecular weight" refers to the statistical average molecular weight by mass of polymer averaged over unit weight.

[0068] The paste mixing process in the prior art is difficult to adapt to binders with high weight-average molecular weights. Positive electrode pastes with high molecular weight binders produced by prior art techniques tend to have high viscosity at shipping, making it difficult to meet coating requirements and prone to serious gelation. The manufacturing method disclosed herein can accommodate binders with weight-average molecular weights up to 8 million by adding the binder in separate steps and adjusting the stirring speed. As a result, the paste still has low viscosity at shipping and after standing for 24 hours, and has good anti-gelling properties, meeting the needs of high molecular weight binders.

[0069] In some embodiments, the third stirring is performed first at low speed, followed by high speed stirring. Note that low speed stirring and high speed stirring are relative terms. When the speed of the low speed stirring in the third stirring is v1 and the speed of the high speed stirring is v2, v1 is slower than v2, and v1 and v2 represent the rotation speeds of the stirring.

[0070] In the third stirring, the dry mixture and binder liquid are first stirred at a low speed to thoroughly disperse the dry mixture in the binder liquid while avoiding excessive shearing of the dry mixture, thereby ensuring the integrity of the positive electrode active material and the conductive agent. After low-speed stirring, the binder liquid coats the surfaces of the positive electrode active material and the conductive agent, preventing excessive shearing of the positive electrode active material and the conductive agent during subsequent high-speed stirring. Further high-speed stirring after low-speed stirring can reduce the viscosity of the paste, thereby providing a positive electrode paste with a low viscosity as shipped for subsequent manufacturing.

[0071] In some embodiments, the revolution speed of the low-speed stirring in the third stirring is 15 rpm to 25 rpm, the rotation speed is 400 rpm to 800 rpm, and the stirring time is 5 minutes to 15 minutes.

[0072] As used herein, the term "rotation speed" refers to the speed at which the agitator rotates about its own axis.

[0073] As used herein, the term "orbital speed" refers to the speed at which the agitator rotates around the tank containing the material.

[0074] In some embodiments, the revolution speed of the slow stirring in the third stirring can be selected from any one of 15 rpm, 20 rpm, and 25 rpm.

[0075] In some embodiments, the rotation speed of the slow stirring in the third stirring can be selected from any one of 400 rpm, 500 rpm, 600 rpm, 700 rpm, and 800 rpm.

[0076] In some embodiments, the stirring time of the low speed stirring in the third stirring can be selected from any one of 5 minutes, 10 minutes, and 15 minutes.

[0077] In some embodiments, the agitator is a planetary mixer. The working principle of a planetary mixer is that after the mixer is started, the planetary carrier rotates, rotating the agitator shaft inside the box, revolving around the axis of the material cylinder and simultaneously rotating at high speed, thereby subjecting the material to strong shearing and kneading action. Note that the manufacturing method provided herein is suitable for all types of planetary mixers.

[0078] If the revolution speed or rotation speed of the low-speed stirring in the third stirring is too slow, or the stirring time is too short, the dry mixture formed from the conductive agent and the active material cannot be effectively dispersed in the binder liquid, and the viscosity of the paste at the time of shipment and after standing for 24 hours will be too high, making the paste prone to gel and resulting in low paste stability.If the revolution speed or rotation speed of the low-speed stirring in the third stirring is too high, or the stirring time is too long, the viscosity of the paste at the time of shipment, the viscosity of the paste after standing for 24 hours, and the gelling phenomenon of the paste will not be significantly improved, and energy will be wasted and production costs will increase.

[0079] From the above, by controlling the revolution speed, rotation speed, and stirring time of the low-speed stirring in the third stirring within appropriate ranges, the paste has low viscosity at the time of shipment, low viscosity after standing for 24 hours, and excellent anti-gelling properties, which is advantageous in improving the coatability, processability, and stability of the paste.

[0080] In some embodiments, the revolution speed of the third stirring is 20 rpm to 30 rpm, the rotation speed is 1000 rpm to 1300 rpm, and the stirring time is 50 minutes to 80 minutes.

[0081] In some embodiments, the revolution speed of the high-speed stirring in the third stirring can be selected from any one of 20 rpm, 25 rpm, and 30 rpm.

[0082] In some embodiments, the rotation speed of the high-speed stirring in the third stirring can be selected from any one of 1000 rpm, 1100 rpm, 1200 rpm, and 1300 rpm.

[0083] In some embodiments, the stirring time of the high speed stirring in the third stirring can be selected from any one of 50 minutes, 60 minutes, 70 minutes, and 80 minutes.

[0084] If the revolution speed or rotation speed of the high-speed stirring in the third stirring is too slow or the stirring time is too short, the primary paste cannot be sheared strongly, and the viscosity of the paste at the time of shipment and after standing for 24 hours will be too high, making the paste prone to gel and resulting in low paste stability.If the revolution speed or rotation speed of the high-speed stirring in the third stirring is too high or the stirring time is too long, the viscosity of the paste at the time of shipment, the viscosity of the paste after standing for 24 hours, and the gelling phenomenon of the paste will not be significantly improved, resulting in wasted energy and reduced production efficiency.

[0085] From the above, by controlling the revolution speed, rotation speed, and stirring time of the high-speed stirring in the third stirring within appropriate ranges, the paste has low viscosity at the time of shipment, low viscosity after standing for 24 hours, and excellent anti-gelling properties, which is advantageous in improving the coatability, processability, and stability of the paste.

[0086] In some embodiments, the rotation speed of the first agitation is 0.

[0087] By controlling the rotation speed of the first stirring to 0, the shear force of the first stirring can be minimized, the possibility of the active material and conductive agent being excessively crushed is sufficiently reduced, and the positive electrode active material and conductive agent have a certain granularity and specific surface area, which is helpful in improving the dispersion effect of the positive electrode active material and conductive agent, reducing the viscosity of the paste after standing for 24 hours, mitigating the gelling phenomenon of the paste, and improving the stability of the paste.

[0088] In some embodiments, the revolution speed of the first stirring is 20 rpm to 30 rpm.

[0089] In some embodiments, the revolution speed of the first stirring can be selected from any one of 20 rpm, 25 rpm, and 30 rpm.

[0090] If the revolution speed of the first stirring is too slow, the positive electrode active material and the conductive agent cannot be mixed effectively, and the viscosity of the paste at the time of shipment and after standing for 24 hours will be too high, making the paste prone to gel and resulting in low paste stability.If the revolution speed of the first stirring is too fast, the viscosity of the paste at the time of shipment, the viscosity of the paste after standing for 24 hours, and the gelling phenomenon of the paste will not be significantly improved, resulting in wasted energy and increased production costs.

[0091] By controlling the revolution speed of the first stirring within an appropriate range, the paste has low viscosity at the time of shipment, low viscosity after standing for 24 hours, and anti-gelling properties, which are advantageous in improving the coatability, processability, and stability of the paste.

[0092] In some embodiments, the stirring time of the first stirring is 5 minutes to 20 minutes, and in some embodiments, the stirring time of the first stirring can be selected from any one of 5 minutes, 10 minutes, 15 minutes, and 20 minutes.

[0093] If the stirring time of the first stirring is too short, the positive electrode active material and the conductive agent cannot be mixed effectively, and the viscosity of the paste at the time of shipment and after standing for 24 hours will be too high, making the paste prone to gel and resulting in low paste stability.If the stirring time of the first stirring is too long, the viscosity of the paste at the time of shipment, the viscosity of the paste after standing for 24 hours, and the gelling phenomenon of the paste will not be significantly improved, resulting in wasted energy and reduced production efficiency.

[0094] By controlling the stirring time of the first stirring within an appropriate range, the paste has low viscosity at the time of shipment, low viscosity after standing for 24 hours, and anti-gelling properties, which are advantageous in improving the coatability, processability, and stability of the paste.

[0095] In some embodiments, the stirring time of the second stirring is 50 to 80 minutes, and in some embodiments, the stirring time of the second stirring can be selected from any one of 50 minutes, 60 minutes, 70 minutes, and 80 minutes.

[0096] If the mixing time of the second mixing is too short, the binder and solvent cannot be mixed effectively, the viscosity of the paste at the time of shipment and after standing for 24 hours will be too high, gel will easily appear in the paste, and the paste will have low stability.If the mixing time of the second mixing is too long, the viscosity of the paste at the time of shipment, the viscosity of the paste after standing for 24 hours, and the gelling phenomenon of the paste will not be significantly improved, and instead will result in wasted energy and reduced production efficiency.

[0097] By controlling the stirring time of the second stirring within an appropriate range, the paste has low viscosity at the time of shipment, low viscosity after standing for 24 hours, and anti-gelling properties, which are advantageous in improving the coatability, processability, and stability of the paste.

[0098] In some embodiments, the revolution speed of the second agitation is 25 rpm to 40 rpm. In some embodiments, the revolution speed of the second agitation can be selected from any one of 25 rpm, 30 rpm, 35 rpm, and 40 rpm.

[0099] If the revolution speed of the second stirring is too slow, the binder and solvent cannot be mixed effectively, and the viscosity of the paste at the time of shipment and after standing for 24 hours will be too high, making the paste prone to gel and resulting in low paste stability.If the revolution speed of the second stirring is too fast, the paste prone to gel will be prone to gel.

[0100] By controlling the revolution speed of the second stirring within an appropriate range, the paste has low viscosity at the time of shipment and after standing for 24 hours, which is also advantageous in alleviating the gelling state of the paste, improving the paste stability, and widening the process window for paste coating.

[0101] In some embodiments, the rotation speed of the second stirring is 1000 rpm to 1300 rpm, and in some embodiments, the rotation speed of the second stirring can be selected from any one of 1000 rpm, 1100 rpm, 1200 rpm, and 1300 rpm.

[0102] If the revolution speed of the second stirring is too slow, the binder and solvent cannot be mixed effectively, and the viscosity of the paste at the time of shipment and after standing for 24 hours will be too high, making the paste prone to gel and resulting in low paste stability.If the revolution speed of the second stirring is too fast, the viscosity of the paste at the time of shipment, the viscosity of the paste after standing for 24 hours, and the gelling phenomenon of the paste will not be significantly improved, resulting in wasted energy and increased production costs.

[0103] By controlling the rotation speed of the second stirring within an appropriate range, the paste has low viscosity at the time of shipment, low viscosity after standing for 24 hours, and anti-gelling properties, which are advantageous in improving the coatability, processability, and stability of the paste.

[0104] In some embodiments, the stirring time of the fourth stirring is 60 minutes to 90 minutes, and in some embodiments, the stirring time of the fourth stirring can be selected from any one of 60 minutes, 70 minutes, 80 minutes, and 90 minutes.

[0105] If the stirring time of the fourth stirring is too short, the binder and solvent cannot be effectively mixed with the primary paste, and the viscosity of the paste at the time of shipment and after standing for 24 hours will be too high, which will lead to the formation of gel in the paste and poor paste stability.If the stirring time of the fourth stirring is too long, the positive electrode active material and conductive agent will be easily crushed, which will lead to the formation of gel in the paste.

[0106] By controlling the stirring time of the fourth stirring within an appropriate range, the paste has low viscosity at the time of shipment and after standing for 24 hours, which is advantageous in alleviating the gelling state of the paste, improving the paste stability, and widening the process window.

[0107] In some embodiments, the revolution speed of the fourth agitation is 25 rpm to 40 rpm. In some embodiments, the revolution speed of the fourth agitation can be selected from any one of 25 rpm, 30 rpm, 35 rpm, and 40 rpm.

[0108] If the revolution speed of the fourth stirring is too slow, the binder and solvent cannot be effectively mixed with the primary paste, and the viscosity of the paste at the time of shipment and after standing for 24 hours will be too high, making the paste prone to gel and resulting in poor paste stability.If the revolution speed of the fourth stirring is too fast, the positive electrode active material and conductive agent will be easily crushed, making the paste prone to gel.

[0109] By controlling the revolution speed of the fourth stirrer within an appropriate range, the paste has low viscosity at the time of shipment and after standing for 24 hours, which is also advantageous in mitigating the gelling state of the paste, improving the paste stability, and widening the process window.

[0110] In some embodiments, the rotation speed of the fourth agitation is 1000 rpm to 1300 rpm. In some embodiments, the rotation speed of the fourth agitation can be selected from any one of 1000 rpm, 1100 rpm, 1200 rpm, and 1300 rpm.

[0111] If the rotation speed of the fourth stirring is too slow, the binder and solvent cannot be effectively mixed with the primary paste, and the viscosity of the paste at the time of shipment and after standing for 24 hours will be too high, making the paste prone to gel and resulting in poor paste stability.If the rotation speed of the fourth stirring is too fast, the positive electrode active material and conductive agent will be easily crushed, making the paste prone to gel.

[0112] By controlling the rotation speed of the fourth stirrer within an appropriate range, the viscosity of the paste at the time of shipment and after standing for 24 hours can be kept low, which is advantageous in alleviating the gelling state of the paste, improving the paste stability, and widening the process window.

[0113] In some embodiments, the positive electrode paste has a solids content of 65% to 70% and a viscosity of 6000 to 31000 mPa·s.

[0114] Both the solids content and viscosity of the positive electrode paste can be measured by any method known in the art: the viscosity can be measured using a rotational viscometer, and the solids content can be measured by weighing the paste before and after removing the water.

[0115] In some embodiments, the solids content of the positive electrode paste can be selected from any one of 65%, 66%, 67%, 68%, 69%, and 70%.

[0116] In some embodiments, the viscosity of the positive electrode paste is 6000 mPa·s, 7000 mPa·s, 8000 mPa·s, 9000 mPa·s, 10000 mPa·s, 11000 mPa·s, 12000 mPa·s, 13000 mPa·s, 14000 mPa·s, 15000 mPa·s, 16000 mPa·s, 17000 mPa·s, 18000 mPa·s, 19000 mPa·s, 2000 mPa·s, 21000 mPa·s, 22000 mPa·s, 23000 mPa·s, 24000 mPa·s, 25000 mPa·s, 26000 mPa·s, 27000 mPa·s, 28000 mPa·s, 29000 mPa·s, 3000 mPa·s, 31000 mPa·s, 32000 mPa·s, 33000 mPa·s, 34000 mPa·s, 35000 mPa·s, 36000 mPa·s, 37000 mPa·s, 38000 mPa·s, 39000 mPa·s, 4000 mPa·s, 41000 mPa·s, 42000 mPa·s, 43000 mPa·s, 44000 mPa·s, 45000 mPa·s, 46000 mPa·s, 47000 mPa·s, 48000 mPa·s, 49000 mPa·s, 5000 mPa·s, 51000 mPa·s, You can select from one of the following: 9000mPa·s, 20000mPa·s, 21000mPa·s, 22000mPa·s, 23000mPa·s, 24000mPa·s, 25000mPa·s, 26000mPa·s, 27000mPa·s, 28000mPa·s, 29000mPa·s, 30000mPa·s, 31000mPa·s.

[0117] The paste formed by the manufacturing method of the present invention has a high solid content, suitable viscosity, and excellent processability, and the paste can be directly used in the subsequent coating process, thereby improving production efficiency.

[0118] In some embodiments, with respect to the total mass of the positive electrode active material, the conductive agent, the binder used in the second stirring, and the binder used in the fourth stirring, the mass percentage of the solvent used in the second stirring is 35% to 45%, and the mass percentage of the solvent used in the fourth stirring is 4% to 10%.

[0119] In some embodiments, in the positive electrode paste, the ratio of the mass of the positive electrode active material, the total mass of the binder, and the mass of the conductive agent is (88 to 96):(2 to 4):(2 to 8).

[0120] The total mass of the binder is the sum of the mass of the binder used in the second mixing and the mass of the binder used in the fourth mixing. The masses of the binder, positive electrode active material, and conductive agent to be added can be determined by one skilled in the art based on the rated range of the mixing device.

[0121] A positive electrode paste within the above range not only has good processability, but also provides a positive electrode sheet after molding with excellent electrical and chemical properties.

[0122] [Positive electrode paste] In one embodiment of the present application, a positive electrode paste is provided, the positive electrode paste having a solids content of 65% to 70%, an initial viscosity of 6000 to 31000 mPa s, and after standing for 24 hours, the viscosity of the positive electrode paste does not exceed 49000 mPa s.

[0123] The initial viscosity refers to the viscosity at the time of shipping immediately after the placement of the positive electrode paste is completed.

[0124] In some embodiments, the positive electrode paste is produced by the method for producing a positive electrode paste according to any of the above embodiments.

[0125] In some embodiments, the viscosity of the positive electrode paste after standing for 24 hours does not exceed 48000 mPa·s, 45000 mPa·s, 41000 mPa·s, 35000 mPa·s, 31000 mPa·s, or 26000 mPa·s.

[0126] The paste formed by the manufacturing method of the present invention has a high solid content, an appropriate viscosity, and excellent processability, and at the same time, the paste has excellent storage stability.

[0127] Furthermore, the secondary battery, battery module, battery pack, and power consuming device of the present application will be described below with reference to the drawings as appropriate.

[0128] In one embodiment of the present application, a secondary battery is provided.

[0129] Generally, a secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. The positive electrode sheet is manufactured from the positive electrode paste manufactured by the manufacturing method according to any one of the embodiments.

[0130] In some embodiments, the secondary battery is one of a lithium ion battery, a sodium ion battery, a magnesium ion battery, and a potassium ion battery.

[0131] During the charge and discharge process of a battery, active ions are inserted and removed between the positive and negative electrode sheets. The electrolyte serves to conduct ions between the positive and negative electrode sheets. The separator, placed between the positive and negative electrode sheets, primarily serves to prevent short circuits between the positive and negative electrodes while allowing ions to pass through.

[0132] [Positive electrode sheet] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, and the positive electrode film layer is manufactured from the positive electrode paste manufactured by the method for manufacturing a positive electrode paste according to any embodiment of the present application or from the positive electrode paste according to any embodiment.

[0133] As an example, the positive electrode current collector has two surfaces facing each other in the thickness direction thereof, and the positive electrode film layer is provided on one or both of the two facing surfaces of the positive electrode current collector.

[0134] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. Examples of the metal foil include aluminum foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0135] In some embodiments, the positive electrode active material may be a positive electrode active material for batteries known in the art. For example, the positive electrode active material may include at least one of an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and a modified compound thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material may also be used. These positive electrode active materials may be used alone or in combination of two or more. Here, examples of lithium transition metal oxides include lithium cobalt oxide (e.g., LiCoO), lithium nickel oxide (e.g., LiNiO), lithium manganese oxide (e.g., LiMnO, LiMnO), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (may be abbreviated as "LiNi") 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (may be abbreviated as "LiNi") 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (may be abbreviated as "LiNi") 0.6 Co 0.2 Mn 0.2O2(NCM 622 (may be abbreviated as "LiNi") 0.8 Co 0.1 Mn 0.1 O2(NCM 811 ), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 O2) and modified compounds thereof, etc. The lithium-containing phosphate having an olivine structure may include, but is not limited to, for example, at least one of lithium iron phosphate (e.g., LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0136] In some embodiments, the positive electrode film layer may further include a binder, such as at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0137] In some embodiments, the positive electrode film layer may further include a conductive agent, for example, at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0138] In some embodiments, a positive electrode sheet can be manufactured by the following method: A positive electrode paste is manufactured from the components for manufacturing the positive electrode sheet, such as a positive electrode active material, a conductive agent, a binder, and a solvent (e.g., N-methyl-2-pyrrolidone), using the method for manufacturing a positive electrode paste according to any embodiment of the present application, and the manufactured positive electrode paste is applied to a positive electrode current collector, followed by processes such as drying and cold pressing, to obtain a positive electrode sheet.

[0139] [Negative electrode sheet] The negative electrode sheet includes a negative electrode active material and includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector.

[0140] As an example, the negative electrode current collector has two surfaces facing each other in the thickness direction thereof, and the negative electrode film layer is provided on one or both of the two facing surfaces of the negative electrode current collector.

[0141] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. The metal foil may be, for example, a copper foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0142] In some embodiments, the negative electrode active material may be a battery negative electrode active material known in the art. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicone-based material, a tin-based material, and lithium titanate. The silicone-based material may be selected from at least one of a silicone element, a silicone oxide, a silicone carbon composite, a silicone nitrogen composite, and a silicone alloy. The tin-based material may be selected from at least one of a tin element, a tin oxide, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery negative electrode active material may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0143] In some embodiments, the negative electrode membrane layer optionally further comprises a binder, which may be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0144] In some embodiments, the negative electrode film layer further optionally includes a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0145] In some embodiments, the negative electrode membrane layer further optionally includes other auxiliary agents, such as a thickener (e.g., carboxymethylcellulose sodium (CMC-Na)).

[0146] In some embodiments, the negative electrode sheet can be manufactured in the following manner: Components for manufacturing the negative electrode sheet, such as a negative electrode active material, a conductive agent, a binder, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode paste, which is then applied to a negative electrode current collector, dried, cold-pressed, and other processes to obtain a negative electrode sheet.

[0147] [Electrolyte] The electrolyte serves to conduct ions between the positive electrode sheet and the negative electrode sheet. The present application does not specifically limit the type of electrolyte, and it can be selected according to needs. For example, the electrolyte may be liquid, gel, or all solid.

[0148] In some embodiments, the electrolyte is an electrolytic solution, which includes an electrolyte salt and a solvent.

[0149] In some embodiments, the electrolyte salt may be chosen from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0150] In some embodiments, the solvent may be chosen from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethyl methyl sulfone, and diethyl sulfone.

[0151] In some embodiments, the electrolyte solution further optionally contains additives. For example, the additives may include a negative electrode film-forming additive, a positive electrode film-forming additive, and may further include additives that can improve some battery performance, such as an additive that improves the overcharge performance of the battery, or an additive that improves the high-temperature or low-temperature performance of the battery.

[0152] [Separator] In some embodiments, the secondary battery further includes a separator. The present application does not particularly limit the type of separator, and any known porous separator with good chemical stability and mechanical stability may be selected.

[0153] In some embodiments, the separator may be made of at least one material selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, without any particular limitations. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, without any particular limitations.

[0154] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be wound or stacked to form an electrode assembly.

[0155] In some embodiments, the secondary battery may include an exterior body, which may be used to package the electrode assembly and the electrolyte.

[0156] In some embodiments, the exterior of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The exterior of the secondary battery may be a pouch, such as a bag-shaped pouch. The pouch may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0157] The present application does not particularly limit the shape of the secondary battery, which may be cylindrical, rectangular, or any other shape. For example, Figure 1 shows an example of a rectangular secondary battery 5.

[0158] In some embodiments, referring to FIG. 2 , the exterior body may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and a side plate connected to the bottom plate, where the bottom plate and the side plate together form a surrounding accommodating cavity. The case 51 has an opening communicating with the accommodating cavity, and the cover plate 53 can cover the opening and seal the accommodating cavity. The positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is packaged in the accommodating cavity. An electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and those skilled in the art can select the number according to actual needs.

[0159] In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0160] Fig. 3 shows an example of a battery module 4. Referring to Fig. 3, in the battery module 4, a plurality of secondary batteries 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fixed by fasteners.

[0161] Optionally, the battery module 4 may further include a housing having an accommodating space, and the plurality of secondary batteries 5 are accommodated in this accommodating space.

[0162] In some embodiments, the battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0163] 4 and 5 show an example of a battery pack 1. Referring to FIGS. 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 is covered by the lower housing 3 to form an enclosed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0164] The present application also provides a power consuming device, the power consuming device including at least one of a secondary battery, a battery module, or a battery pack according to the present application. The secondary battery, the battery module, or the battery pack may be used as a power source for the power consuming device or as an energy storage unit for the power consuming device. The power consuming device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc.

[0165] The power consumption device can be selected from a secondary battery, a battery module, or a battery pack depending on its usage needs.

[0166] 6 shows an example of a power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, in which a battery pack or a battery module can be used to meet the demand for high power output and high energy density of the secondary battery of the power consuming device.

[0167] Other examples of the device may be a mobile phone, a tablet computer, a laptop computer, etc. These devices are generally required to be lightweight and can use a secondary battery as a power source.

[0168] Example The following describes examples of the present application. The examples described below are illustrative and are intended only to interpret the present application and should not be understood as limitations on the present application. If specific techniques or conditions are not specified in the examples, they will be carried out according to the techniques or conditions described in literature in the field or in accordance with the product specifications. If the manufacturer of the reagents or instruments used is not specified, they are all ordinary products that are commercially available.

[0169] 1. Preparation method Example 1 1) Manufacturing of positive electrode paste First mixing: 25 kg of conductive carbon black and 1,200 kg of lithium iron phosphate are mixed and stirred in a double planetary mixer for 15 minutes, with an orbital speed of 25 rpm and a rotation speed of 0, to obtain a dry mixture.

[0170] Second stirring: 17 kg of polyvinylidene fluoride binder with a weight average molecular weight of 1.8 million and 500 kg of N-methyl-2-pyrrolidone are mixed and stirred at an orbital speed of 25 rpm, a rotation speed of 1200 rpm, and a stirring time of 60 minutes to obtain a binder liquid.

[0171] Third stirring: The dry mixture is added to the binder liquid and mixed and stirred, and stirred for 10 minutes at an orbital speed of 20 rpm and a rotation speed of 600 rpm, and then further stirred for 70 minutes at an orbital speed of 25 rpm and a rotation speed of 1200 rpm to obtain a primary paste.

[0172] Fourth stirring: Mix and stir 8 kg of polyvinylidene fluoride binder with a weight-average molecular weight of 1.8 million, 60 kg of N-methyl-2-pyrrolidone, and the primary paste at a revolution speed of 30 rpm and a rotation speed of 1200 rpm for 70 minutes to obtain a positive electrode paste with a viscosity of 18000 mPa·s and a solids content of 68%.

[0173] Examples 2 and 3 The manufacturing method was substantially the same as in Example 1, except that the mass percentage of the binder in the second stirring was adjusted, and the specific parameters are as shown in Table 1.

[0174] Examples 4 to 9 The manufacturing method was substantially the same as in Example 1, except that the weight average molecular weight of the binder polyvinylidene fluoride was adjusted. Specific parameters are as shown in Table 1.

[0175] Examples 10 to 67 The production method was substantially the same as in Example 1, except that the stirring parameters were adjusted. The specific parameters are as shown in Table 1.

[0176] Comparative Example 1 1) 8 kg of conductive carbon black and 1,200 kg of lithium iron phosphate are mixed and stirred in a double planetary mixer for 15 minutes, with an orbital speed of 25 rpm and a rotation speed of 0, to obtain a dry mixture.

[0177] 2) 18 kg of polyvinylidene fluoride binder with a weight average molecular weight of 1.8 million and 560 kg of N-methyl-2-pyrrolidone are mixed and stirred at an orbital speed of 25 rpm, a rotation speed of 1200 rpm, and a stirring time of 60 minutes to obtain a binder liquid.

[0178] 3) Add the dry mixture to the binder liquid and stir at low speed for 200 minutes at a revolution speed of 25 rpm and a rotation speed of 1200 rpm, then stir at high speed for 60 minutes at a revolution speed of 30 rpm and a rotation speed of 1300 rpm to obtain the positive electrode paste.

[0179] Comparative Examples 2 to 5 The manufacturing method was substantially the same as that of Comparative Example 1, except that the weight average molecular weight of the binder polyvinylidene fluoride was adjusted. Specific parameters are as shown in Table 1.

[0180] Comparative Example 6 1) 18 kg of polyvinylidene fluoride binder with a weight average molecular weight of 1.8 million and 560 kg of N-methyl-2-pyrrolidone are mixed and stirred at an orbital speed of 25 rpm, a rotation speed of 1200 rpm, and a stirring time of 60 minutes to obtain a binder liquid.

[0181] 2) 1200 kg of lithium iron phosphate was added to the binder liquid and mixed and stirred for 60 minutes, the revolution speed was 25 rpm, and the rotation speed was 1200 rpm to obtain a primary paste.

[0182] 3) 8 kg of conductive carbon black is added to the primary paste and mixed and stirred, the stirring time is 140 minutes, the revolution speed is 30 rpm, and the rotation speed is 1200 rpm to obtain a positive electrode paste.

[0183] Comparative Examples 7 to 10 The production method was substantially the same as that of Comparative Example 6, except that the weight average molecular weight of the polyvinylidene fluoride binder was adjusted. Specific parameters are as shown in Table 1.

[0184] Comparative Examples 11 to 12 The manufacturing method was substantially the same as in Example 1, except that the mass percentage of the binder in the second stirring was adjusted, and the specific parameters are as shown in Table 1.

[0185] 2. Paste characteristic test 1. Viscosity test of paste before shipping The manufactured positive electrode paste is left to stand for 10 minutes before shipping. The viscosity value measured initially using a Dveslvtjo rotational viscometer (BROOKFIELD) is recorded as the viscosity at shipping. Test conditions are 25°C, rotation speed 12 rpm. If the measured viscosity is 2000 mPa·s or higher, a 64 rotor is used. If the measured viscosity is less than 2000 mPa·s, a 62 rotor is used. Three measurements are taken in parallel and the average value is calculated.

[0186] 2. Viscosity change test after leaving the paste undisturbed for 24 hours After leaving the paste to stand for 24 hours, the viscosity was tested again using a Dveslvtjo rotational viscometer (BROOKFIELD). The viscosity value measured was recorded as the 24-hour viscosity. The test conditions were 25°C, rotation speed 12 rpm. If the measured viscosity was 2000 mPa·s or higher, a 64 rotor was used. If the measured viscosity was less than 2000 mPa·s, a 62 rotor was used. Three measurements were taken in parallel, and the average value was calculated.

[0187] 3. Gel state test after leaving the paste undisturbed for 24 hours After leaving the paste to stand for 24 hours, the paste in the beaker is lifted up with a steel ruler and the state of gelation of the paste is judged from the state of fluidity of the paste.

[0188] The gel-free condition is when the paste flows naturally and continuously, the paste advects over the surface of the steel scale, and there is no clumping.

[0189] The slight gelling state is when the paste flows naturally and continuously, but is thin and the paste spreads essentially evenly over the surface of the steel scale, but with slight lumps.

[0190] The state of moderate gelation is that the paste drips spontaneously, occasionally stops, the flow is discontinuous, the paste does not spread evenly on the surface of the steel scale, and there are obvious lumpy clumps.

[0191] Severe gelation is when the paste is unable to flow, falls in clumps, or remains on the steel scale and does not flow off.

[0192] 4. Paste solid content test Take the aluminum foil and weigh it with a moisture meter, set it as M0, and clear the display. The moisture meter is MOC-120H.

[0193] Take the top layer of paste, apply a small amount to a polar sheet, then place it in a moisture meter and weigh it to determine M1.

[0194] The equipment is closed, and drying is started. After completion, the weighing data is recorded and designated as M2, and the solid content is calculated as (M2-M0) / (M1-M0).

[0195] 3. Analysis of the test results of each example and comparative example The positive electrode pastes of the examples and comparative examples were prepared according to the above methods, and the parameters and performance measurement results are shown in Table 1 below.

[0196] [Table 1-1] [Table 1-2] [Table 1-3] [Table 1-4] [Table 1-5] [Table 1-6] [Table 1-7]

[0197] As can be seen from the results in Table 1, the positive electrode pastes in Examples 1 to 67 were all produced using the paste manufacturing method disclosed herein, and each included a first stirring, a second stirring, a third stirring, and a fourth stirring. In the first stirring, the positive electrode active material and the conductive agent were mixed and stirred to produce a dry mixture. In the second stirring, the binder and the solvent were mixed and stirred to produce a binder liquid. In the third stirring, the dry mixture and the binder liquid were mixed and stirred to produce a primary paste. In the fourth stirring, the binder, the solvent, and the primary paste were mixed and stirred to produce a positive electrode paste. The binder and the solvent used in the second stirring were the same as those used in the fourth stirring, respectively. The weight percentage of the binder used in the second stirring was 50% to 70% and the weight percentage of the binder used in the fourth stirring were 30% to 50% of the total weight of the binder used in the second stirring and the binder used in the fourth stirring, respectively.

[0198] As can be seen from a comparison of Examples 1 to 9 and Comparative Examples 1 to 10, the paste manufacturing method of the present disclosure is versatile and can be adapted to pastes containing polyvinylidene fluoride binders with weight-average molecular weights of 200,000 to 8,000,000, and is universal for both low-molecular-weight binders and high-molecular-weight binders.

[0199] As can be seen from the comparative examples, the manufacturing processes in the prior art cannot improve the gelation state of any binder with a weight average molecular weight of 1.8 million.By using the manufacturing method disclosed in this application, a paste containing a binder with a weight average molecular weight of up to 8 million still has low viscosity at the time of shipping and good anti-gelling properties, which can meet the needs of the next generation of high molecular weight binders.

[0200] As can be seen from the comparison between Examples 1 to 3 and Comparative Examples 11 to 12, by controlling the proportion of binder added in the first stirring to 50% to 70% of the total mass of binder, the viscosity of the paste at the time of shipment can be reduced, which effectively alleviates the gelation of the paste and widens the process window of paste coating.

[0201] Comparing Examples 1, 5 to 9 with Example 4, it can be seen that by controlling the weight average molecular weight of the polyvinylidene fluoride binder to 800,000 to 8,000,000, there is no significant change in the viscosity of the paste at the time of shipment, the viscosity of the paste after leaving it to stand for 24 hours, or the gelling phenomenon of the paste, and at the same time, the adhesiveness requirements of the polar sheet can be met.

[0202] As can be seen from a comparison of Examples 27 to 29 with Example 26, and Examples 31 to 33 with Example 30, by first performing low-speed stirring and then performing high-speed stirring in the third stirring, it is possible to effectively reduce the viscosity of the paste at the time of shipment and the viscosity of the paste after it has been left to stand for 24 hours, thereby mitigating gelation of the paste and improving the coatability and processability of the paste.

[0203] A comparison of Example 1, Examples 11-12 and Example 10 shows that by controlling the stirring time of low-speed stirring in the third stirring to 5-15 minutes, the viscosity of the paste at the time of shipment and the viscosity after standing for 24 hours can be reduced, gelation of the paste can be mitigated, and the process window of paste coating can be widened. A comparison of Example 1, Examples 11-12 and Example 13 shows that by controlling the stirring time of low-speed stirring in the third stirring to 5-15 minutes, the quality and efficiency of paste mixing can be improved, the viscosity at the time of shipment can be reduced, and gelation of the paste can be mitigated.

[0204] A comparison of Example 1, Examples 15-16 and Example 14 shows that controlling the revolution speed of the slow stirring in the third stirring to 15-25 rpm can reduce the viscosity of the paste at the time of shipment and the viscosity after standing for 24 hours, mitigate paste gelation and widen the process window for paste coating. A comparison of Example 1, Examples 15-16 and Example 17 shows that controlling the revolution speed of the slow stirring in the third stirring to 15-25 rpm can achieve both paste mixing quality and cost, reduce the viscosity at the time of shipment and mitigate paste gelation.

[0205] A comparison of Example 1, Examples 19-20 and Example 18 shows that by controlling the rotation speed of the slow stirring in the third stirring to 400 rpm to 800 rpm, the viscosity of the paste at the time of shipment and the viscosity after standing for 24 hours can be reduced, the gelation of the paste can be alleviated, the shelf life of the paste can be improved, and the process window of the paste coating can be widened. A comparison of Example 1, Examples 19-20 and Example 21 shows that by controlling the rotation speed of the slow stirring in the third stirring to 400 rpm to 800 rpm, the quality and cost of paste mixing can be both achieved, the viscosity at the time of shipment can be reduced, and the gelation of the paste can be alleviated.

[0206] A comparison of Example 1, Examples 23-24 and Example 22 shows that by controlling the stirring time of high-speed stirring in the third stirring to 50-80 minutes, the viscosity of the paste at the time of shipment and the viscosity after standing for 24 hours can be reduced, paste gelation can be mitigated, the paste shelf life can be improved, and the process window for paste coating can be widened. A comparison of Example 1, Examples 23-24 and Example 25 shows that by controlling the stirring time of high-speed stirring in the third stirring to 50-80 minutes, the quality and efficiency of paste mixing can be improved, the viscosity at the time of shipment can be reduced, and paste gelation can be mitigated.

[0207] As can be seen from a comparison of Example 1, Examples 27-28 and Example 26, by controlling the revolution speed of high-speed stirring in the third stirring to 20 rpm to 30 rpm, it is possible to reduce the viscosity of the paste at the time of shipment and the viscosity after standing for 24 hours, mitigate paste gelling, improve the paste shelf life and widen the process window for paste coating. As can be seen from a comparison of Example 1, Examples 15-16 and Example 17, it is possible to achieve both paste mixing quality and cost by controlling the revolution speed of low-speed stirring in the third stirring to 15 rpm to 25 rpm.

[0208] As can be seen from a comparison of Example 1, Examples 31-32 and Example 30, by controlling the rotation speed of the high-speed stirring in the third stirring to 1000 rpm to 1300 rpm, it is possible to reduce the viscosity of the paste at the time of shipment and the viscosity after standing for 24 hours, mitigate paste gelling, improve the paste shelf life and widen the process window for paste coating. As can be seen from a comparison of Example 1, Examples 31-32 and Example 33, it is possible to achieve both paste mixing quality and cost by controlling the rotation speed of the high-speed stirring in the third stirring to 1000 rpm to 1300 rpm.

[0209] As can be seen from the comparison between Example 1 and Examples 34 to 35, by controlling the rotation speed of the first stirring to 0, the viscosity of the paste after standing for 24 hours can be reduced, the gelling phenomenon of the paste can be alleviated, the stability of the paste can be improved, and the process window can be widened.

[0210] As can be seen from a comparison of Example 1, Examples 37-38, and Example 36, controlling the mixing time of the first mixing to 5-20 minutes can reduce the viscosity of the paste at the time of shipment and after standing for 24 hours, mitigate the gelling phenomenon of the paste, improve the paste stability, and widen the process window. As can be seen from a comparison of Example 1, Examples 37-38, and Example 39, controlling the mixing time of the first mixing to 5-20 minutes can achieve both paste mixing quality and efficiency, reduce the viscosity at the time of shipment, and mitigate the gelling of the paste.

[0211] As can be seen from a comparison of Example 1, Examples 41 and 42 with Example 40, controlling the revolution speed of the first stirring to 20 to 30 rpm reduces the viscosity of the paste at the time of shipment and after standing for 24 hours, alleviates the gelling phenomenon of the paste, improves the paste stability, and widens the process window. As can be seen from a comparison of Example 1, Examples 41 and 42 with Example 43, controlling the revolution speed of the first stirring to 20 to 30 rpm reduces the viscosity of the paste at the time of shipment and alleviates the gelling phenomenon of the paste, improves the paste stability, and widens the process window.

[0212] As can be seen from a comparison of Example 1, Examples 45-46, and Example 44, controlling the mixing time of the second mixing to 50-80 minutes can reduce the viscosity of the paste at the time of shipment and after standing for 24 hours, mitigate the gelling phenomenon of the paste, improve the paste stability, and widen the process window. As can be seen from a comparison of Example 1, Examples 45-46, and Example 47, controlling the mixing time of the second mixing to 50-80 minutes can achieve both paste mixing quality and efficiency, reduce the viscosity at the time of shipment, and mitigate the gelling of the paste.

[0213] As can be seen from a comparison of Example 1, Examples 49-50, and Example 48, controlling the revolution speed of the second stirring to 25-40 rpm can reduce the viscosity of the paste at the time of shipment and after standing for 24 hours, mitigate the gelling phenomenon of the paste, improve the paste stability, and widen the process window.As can be seen from a comparison of Example 1, Examples 49-50, and Example 51, controlling the revolution speed of the second stirring to 25-40 rpm can mitigate the gelling phenomenon of the paste, improve the paste stability, and widen the process window.

[0214] As can be seen from a comparison of Example 1, Examples 53-54, and Example 52, controlling the rotation speed of the second agitation to 1000 rpm to 1300 rpm reduces the viscosity of the paste at the time of shipment and after standing for 24 hours, alleviates the gelling phenomenon of the paste, improves the paste stability, and widens the process window. As can be seen from a comparison of Example 1, Examples 53-54, and Example 55, controlling the rotation speed of the second agitation to 1000 rpm to 1300 rpm reduces the viscosity of the paste at the time of shipment and alleviates the gelling phenomenon of the paste, improves the paste stability, and widens the process window.

[0215] As can be seen from a comparison of Example 1, Examples 57-58, and Example 56, controlling the stirring time of the fourth stirring to 60-90 minutes can reduce the viscosity of the paste at the time of shipment and after standing for 24 hours, mitigate the gelling phenomenon of the paste, improve the paste stability, and widen the process window. As can be seen from a comparison of Example 1, Examples 57-58, and Example 59, controlling the stirring time of the fourth stirring to 60-90 minutes can mitigate the gelling phenomenon of the paste, improve the paste stability, and widen the process window.

[0216] As can be seen from a comparison of Example 1, Examples 61-62, and Example 60, controlling the revolution speed of the fourth stirring to 25 rpm to 40 rpm can reduce the viscosity of the paste at the time of shipment and after standing for 24 hours, mitigate the gelling phenomenon of the paste, improve the paste stability, and widen the process window. As can be seen from a comparison of Example 1, Examples 61-62, and Example 63, controlling the revolution speed of the fourth stirring to 25 rpm to 40 rpm can mitigate the gelling phenomenon of the paste, improve the paste stability, and widen the process window.

[0217] As can be seen from a comparison of Example 1, Examples 65-66, and Example 64, controlling the rotation speed of the fourth stirring to 1000 rpm to 1300 rpm can reduce the viscosity of the paste at the time of shipment and after standing for 24 hours, mitigate the gelling phenomenon of the paste, improve the paste stability, and widen the process window. As can be seen from a comparison of Example 1, Examples 65-66, and Example 67, controlling the rotation speed of the fourth stirring to 1000 rpm to 1300 rpm can mitigate the gelling phenomenon of the paste, improve the paste stability, and widen the process window.

[0218] As can be seen from the examples, the viscosity of the positive electrode paste with a solid content of 65% to 70% disclosed in the present application is 6000 mPa·s to 31000 mPa·s, and the positive electrode paste has good coatability and processability.

[0219] As can be seen from the examples, the mass percentage of the solvent used in the second stirring is controlled to 35% to 45%, and the mass percentage of the solvent used in the fourth stirring is controlled to 4% to 10%, relative to the total mass of the positive electrode active material, the conductive agent, the binder used in the second stirring, and the binder used in the fourth stirring.

[0220] As can be seen from the examples, the solids content of the positive electrode paste disclosed herein is 65-70%, the initial viscosity of the positive electrode paste is 6000-31000 mPa·s, and after standing for 24 hours, the viscosity of the positive electrode paste does not exceed 49000 mPa·s.

[0221] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any embodiment that has substantially the same configuration as the technical idea and achieves the same effects within the scope of the technical solution of the present application is included within the technical scope of the present application. It should be noted that various modifications that a person skilled in the art can make to the embodiments and other forms formed by combining some of the components of the embodiments are also included within the scope of the present application, as long as they do not deviate from the spirit of the present application. [Explanation of symbols]

[0222] 1 battery pack, 2 upper housing, 3 lower housing, 4 battery module, 5 secondary battery, 51 case, 52 electrode assembly, 53 cover plate

Claims

1. A method for producing a positive electrode paste, a first agitation, a second agitation, a third agitation, and a fourth agitation; In the first stirring step, the positive electrode active material and the conductive agent are mixed and stirred to prepare a dry mixture; In the second stirring, the binder and the solvent are mixed and stirred to produce a binder liquid; In the third stirring, the dry mixture and the binder liquid are mixed and stirred to produce a primary paste; In the fourth stirring step, the binder, the solvent, and the primary paste are mixed and stirred to prepare a positive electrode paste; the binder and the solvent used in the second stirring are the same as the binder and the solvent used in the fourth stirring, respectively, and the mass percentage of the binder used in the second stirring is 50% to 70% and the mass percentage of the binder used in the fourth stirring is 30% to 50% with respect to the total mass of the binder used in the second stirring and the binder used in the fourth stirring.

2. The method for producing a positive electrode paste according to claim 1, wherein the binder contains at least polyvinylidene fluoride having a weight average molecular weight of 800,000 to 8,000,000.

3. 3. The method for producing a positive electrode paste according to claim 1, wherein the third stirring step is first performed at a low speed and then at a high speed.

4. 4. The method for producing a positive electrode paste according to claim 3, wherein the revolution speed of the low-speed stirring in the third stirring is 15 rpm to 25 rpm, the rotation speed is 400 rpm to 800 rpm, and the stirring time is 5 minutes to 15 minutes.

5. 5. The method for producing a positive electrode paste according to claim 3, wherein the third stirring has a revolution speed of 20 rpm to 30 rpm, a rotation speed of 1000 rpm to 1300 rpm, and a stirring time of 50 minutes to 80 minutes.

6. The method for producing a positive electrode paste according to any one of claims 1 to 5, wherein the rotation speed of the first stirring is 0.

7. The method for producing a positive electrode paste according to any one of claims 1 to 6, wherein the revolution speed of the first stirring is 20 rpm to 30 rpm.

8. The method for producing a positive electrode paste according to any one of claims 1 to 7, wherein the first stirring is performed for a period of 5 to 20 minutes.

9. The method for producing a positive electrode paste according to any one of claims 1 to 8, wherein the second stirring is performed for a period of 50 to 80 minutes.

10. The method for producing a positive electrode paste according to any one of claims 1 to 9, wherein the revolution speed of the second stirring is 25 rpm to 40 rpm.

11. The method for producing a positive electrode paste according to any one of claims 1 to 10, wherein the rotation speed of the second stirring is 1000 rpm to 1300 rpm.

12. The method for producing a positive electrode paste according to any one of claims 1 to 11, wherein the fourth stirring is performed for a stirring time of 60 to 90 minutes.

13. The method for producing a positive electrode paste according to any one of claims 1 to 12, wherein the revolution speed of the fourth stirring is 25 rpm to 40 rpm.

14. The method for producing a positive electrode paste according to any one of claims 1 to 13, wherein the rotation speed of the fourth stirring is 1000 rpm to 1300 rpm.

15. The method for producing a positive electrode paste according to any one of claims 1 to 14, wherein the positive electrode paste has a solid content of 65% to 70% and a viscosity of 6000 to 31000 mPa s.

16. 16. The method for producing a positive electrode paste according to claim 1, wherein a mass percentage of the solvent used in the second stirring is 35% to 45% and a mass percentage of the solvent used in the fourth stirring is 4% to 10% relative to a total mass of the positive electrode active material, the conductive agent, the binder used in the second stirring, and the binder used in the fourth stirring.

17. 17. The method for producing a positive electrode paste according to claim 1, wherein in the positive electrode paste, a ratio of a mass of the positive electrode active material, a total mass of the binder, and a mass of the conductive agent is (88 to 96):(2 to 4):(2 to 8).

18. 18. The method for manufacturing a positive electrode paste according to claim 1, wherein the positive electrode active material is at least one of lithium iron phosphate and a modified material thereof, or lithium nickel cobalt manganese oxide and a modified material thereof, and the modified material is manufactured by one or more modification methods of doping, conductive carbon coating, conductive metal coating, and conductive polymer coating.

19. The method for producing a positive electrode paste according to any one of claims 1 to 18, wherein the solvent is one or more of N-methyl-2-pyrrolidone, N,N-dimethylpropionamide, N,N-diethylpropionamide, N,N-dipropylpropionamide, N,N-dibutylpropionamide, N,N-dimethylethylpropionamide, and 3-butoxy-N-methylpropionamide.

20. A positive electrode paste, characterized in that it is produced by the method for producing a positive electrode paste according to any one of claims 1 to 19.

21. 21. The positive electrode paste of claim 20, wherein the solid content is 65% to 70%, the initial viscosity is 6,000 to 31,000 mPa s, and the viscosity after standing for 24 hours does not exceed 49,000 mPa s.

22. A secondary battery comprising a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte, wherein the positive electrode sheet is manufactured from at least one of the positive electrode paste manufactured by the method for manufacturing a positive electrode paste according to any one of claims 1 to 19, and the positive electrode paste according to claim 20 or 21.

23. 23. The secondary battery according to claim 22, which is any one of a lithium ion battery, a sodium ion battery, a magnesium ion battery, and a potassium ion battery.

24. A battery module comprising the secondary battery according to claim 22 or 23.

25. A battery pack comprising at least one of the secondary battery according to claim 22 or 23 and the battery module according to claim 24.

26. A power consumption device comprising at least one selected from the group consisting of the secondary battery according to claim 22 or 23, the battery module according to claim 24, and the battery pack according to claim 25.

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