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

[0002] In recent years, as the range of applications for secondary batteries has expanded, they are widely used in energy storage and power systems such as hydroelectric, thermal, wind, 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 foundation for forming electrodes and is the first step in secondary battery production. The properties of the electrode paste significantly affect subsequent electrode production and battery performance. Cath electrode paste is a solid-liquid phase mixture system mainly formed by positive electrode active material, conductive agent, binder, and 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 generally one-step methods, where each component in the positive electrode active material paste is directly mixed and stirred. However, one-step manufacturing methods cannot meet the manufacturing needs of binders with different weight-average molecular weights, resulting in low versatility of the paste mixing process and disadvantages in reducing manufacturing costs. Therefore, there is a need to develop new paste manufacturing methods to adapt to binders with different weight-average molecular weights. [Overview of the project]

[0004] This invention was made in view of the above-mentioned problems, and its purpose is to provide a method for manufacturing a cathode paste for secondary batteries that can be adapted to binders of different weight-average molecular weights, broaden the process window for coating the cathode paste, and improve the processability of the cathode paste.

[0005] To achieve the above objective, this application provides a method for manufacturing a positive electrode paste, comprising a first stirring, a second stirring, a third stirring, and a 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 mass percentage of the binder used in the second stirring is 50% to 70% of the total mass of the binders used in the second and fourth stirrings, and the mass percentage of the binder used in the fourth stirring is 30% to 50%.

[0006] As a result, the method for manufacturing cathode paste disclosed herein has broader versatility compared to conventional methods for manufacturing cathode paste, is adaptable to pastes containing binders of different weight-average molecular weights, and, compared to conventional methods, reduces the viscosity of the cathode paste at the time of shipment and after standing for 24 hours by performing paste mixing in separate steps, mitigates the gelation phenomenon of the cathode paste, improves the adaptability of the manufacturing method to high molecular weight binders, and the manufacturing method has broader universality, widens the process window for applying cathode paste, and improves the processability of cathode paste.

[0007] In any embodiment, the binder comprises polyvinylidene fluoride having a weight-average molecular weight of at least 800,000 to 8,000,000.

[0008] The manufacturing method disclosed herein is universal to low molecular weight polyvinylidene fluoride binders and high molecular weight polyvinylidene fluoride binders, and can effectively mitigate the gelation phenomenon of different pastes, thereby improving production efficiency and broadening the paste application process window. The manufacturing method disclosed herein can be applied to binders with a weight-average molecular weight reaching 8 million, thereby enabling pastes containing high weight-average molecular weight binders to still have low viscosity at shipment and anti-gelation properties, meeting the needs of next-generation binder use.

[0009] In any embodiment, the third stirring is performed first at low speed, followed by high-speed stirring.

[0010] In the third stirring stage, the dry mixture and binder liquid are first stirred at low speed to ensure that the dry mixture is sufficiently dispersed in the binder liquid, while simultaneously preventing excessive shearing of the dry mixture and ensuring the integrity of the positive electrode active material and conductive agent. Furthermore, the binder liquid that has undergone low-speed stirring covers the positive electrode active material and conductive agent, preventing the destruction of the structure and dimensions of the positive electrode active material and conductive agent during subsequent high-speed stirring. By performing high-speed stirring after low-speed stirring, the viscosity of the paste can be reduced while guaranteeing the properties of the materials.

[0011] In any embodiment, the orbital speed of the low-speed stirring in the third stirring is 15 revolutions / min to 25 revolutions / min, the rotational speed is 400 revolutions / min to 800 revolutions / min, and the stirring time is 5 minutes to 15 minutes.

[0012] By controlling the orbital speed, rotational speed, and stirring time of high-speed stirring in the third stirring stage within an appropriate range, the paste has low viscosity at the time of shipment, low viscosity after standing for 24 hours, and excellent gelation prevention properties, which is advantageous in improving the coating properties, processability, and stability of the paste.

[0013] In any embodiment, the revolution speed of high-speed stirring in the third stirring step 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 high-speed stirring in the third stirring step within appropriate ranges, the paste has low viscosity at shipment, low viscosity after standing for 24 hours, excellent anti-gelling properties, and is advantageous for improving the coating property, processability and stability of the paste.

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

[0016] By controlling the rotation speed of the first stirring step to 0, the shearing force of the first stirring can be minimized, the possibility that the positive electrode active material and the conductive agent are excessively crushed is sufficiently reduced, it is ensured that the positive electrode active material and the conductive agent maintain certain granularity and specific surface area, which helps improve the dispersion effect of the positive electrode active material and the conductive agent, reduces the viscosity of the paste after standing for 24 hours, alleviates the gelling phenomenon of the paste, and improves the stability of the paste.

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

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

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

[0020] By controlling the stirring time of the first stirring step within an appropriate range, the paste has low viscosity at shipment, low viscosity after standing for 24 hours, and anti-gelling properties, which is advantageous for improving the coating property, 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 a low viscosity at shipment, a low viscosity after standing for 24 hours, and anti-gelling properties, which is advantageous for improving the coating property, 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 paste has a low viscosity at shipment and a low viscosity after standing for 24 hours, which is simultaneously advantageous for alleviating the gelling state of the paste, improves the stability of the paste and broadens 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 a low viscosity at shipment, a low viscosity after standing for 24 hours, and anti-gelling properties, thereby improving the coating property, 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 a low viscosity at shipment and a low viscosity after standing for 24 hours, which is simultaneously advantageous for alleviating the gelling state of the paste, improves the stability of the paste and broadens the process window.

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

[0030] By controlling the orbital speed of the fourth stirring within an appropriate range, the paste has low viscosity upon shipment and low viscosity after standing for 24 hours, while simultaneously mitigating the gelling state of the paste, improving 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 stirring within an appropriate range, the paste has low viscosity upon shipment and low viscosity after standing for 24 hours, while simultaneously mitigating the gelling state of the paste, improving paste stability and widening the process window.

[0033] In any 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 this invention has a high solid content, appropriate viscosity, and excellent processability. This paste can be used directly in subsequent coating processes, thereby improving production efficiency.

[0035] In any embodiment, 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% 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.

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

[0037] The positive electrode paste within the above range not only exhibits good processability, but also results in superior electrical and chemical properties for the resulting positive electrode sheet after molding.

[0038] In any embodiment, the positive electrode active material is at least one of lithium iron phosphate and its modifier, or lithium nickel cobalt manganese oxide and its modifier, wherein the modifier is produced by one or more modification methods, including 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, a positive electrode paste manufactured by the method for manufacturing a positive electrode paste according to the first aspect is provided.

[0041] In any embodiment, the solid content of the positive electrode paste is 65% to 70%, the initial viscosity of the positive electrode paste is 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 in this application has a high solid content, appropriate viscosity, excellent processability, and excellent storage properties.

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

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

[0045] A fourth aspect of the present application further provides a battery module including the secondary battery described in the third aspect of the present application.

[0046] According to the fifth aspect of this application, a battery pack is provided that includes a secondary battery as described in the third aspect of this application or a battery module as described in the fourth aspect of this application.

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

[0048] [Figure 1] This is a schematic diagram of a secondary battery according to one embodiment of the present application. [Figure 2] Figure 1 is an exploded view of a secondary battery according to one embodiment of this application. [Figure 3] This is a schematic diagram of a battery module according to one embodiment of the present application. [Figure 4] This is a schematic diagram of a battery pack according to one embodiment of the present application. [Figure 5] Figure 4 is an exploded view of a battery pack according to one embodiment of this application. [Figure 6] This is a schematic diagram of a power consumption device using a secondary battery as a power source according to one embodiment of the present application. [Modes for carrying out the invention]

[0049] The following describes in detail embodiments of the positive electrode active material and its manufacturing method, positive electrode sheet, secondary battery, battery module, battery pack, and power consumption device disclosed in this application, with reference to the drawings as appropriate. However, unnecessary detailed explanations may be omitted. For example, detailed explanations of well-known matters and redundant explanations of structures that are actually the same may be omitted. This is to avoid making the following explanation unnecessarily long and to make it easily understandable to those skilled in the art. The drawings and the following explanation are provided to enable those skilled in the art to fully understand this application and are not intended to limit the topics described in the claims.

[0050] The “range” disclosed in this application is limited in the form of a lower limit and an upper limit, and a given range is limited by selecting one lower limit and one upper limit, which define the boundary of a particular range. The range thus limited may or may not include the endpoints, and any combination is possible, that is, any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 can also be assumed. Furthermore, if 1 and 2 are listed as the minimum range values ​​and 3, 4, and 5 are listed as the maximum range values, then the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 can all be assumed. In this application, unless otherwise specified, the numerical range “a-b” represents an abbreviated expression for any combination of real numbers a-b, where a and b are both real numbers. For example, the numerical range "0 to 5" indicates that all real numbers between "0 to 5" have already been listed in this specification, and "0 to 5" is simply a shortened expression for combinations of these numbers. Also, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that this parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0051] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical inventions.

[0052] Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical concepts.

[0053] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, the fact that the method includes steps (a) and (b) means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, the fact that the method referred to above may further include step (c) means that step (c) may be added to the method in any order, for example the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), and so on.

[0054] Unless otherwise specified, the terms “includes” and “inclusive” as used in this application may be open-ended or closed-ended. For example, “includes” and “inclusive” may further include or include other components not listed, or may include or include only the components listed.

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

[0056] A positive electrode paste is a solid-liquid phase mixture system primarily composed of a positive electrode active material, a conductive agent, a binder, and a solvent. To improve the uniformity of the distribution of different components in the system, paste mixing is generally performed using processes such as stirring, ball milling, or ultrasound. However, conventional paste mixing processes are generally only applicable to paste systems with fixed components, lacking versatility, and often require adjustment when the physical properties of each component in the paste change. For example, conventional paste mixing processes cannot be applied to high molecular weight binders, nor can they be applied to binders with high weight-average molecular weight dispersion and low batch production stability. When pastes using binders from different batches are manufactured using the same conventional paste mixing process, significant performance differences occur, gel formation is common in the paste, and it becomes difficult to meet the production needs of polar sheets.

[0057] [Method for manufacturing positive electrode paste] Based on this, the present application provides a method for manufacturing a positive electrode paste, comprising a first stirring, a second stirring, a third stirring, and a 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 mass percentage of the binder used in the second stirring is 50% to 70% of the total mass of the binders used in the second and fourth stirrings, and the mass percentage of the binder used in the fourth stirring is 30% to 50%.

[0058] In some embodiments, the positive electrode active material is a lithium-containing transition metal oxide. In some embodiments, the positive electrode active material is at least one of lithium iron phosphate and its modifier, lithium nickel cobalt manganese oxide and its modifier, wherein the modifier is produced by one or more modification methods, including doping, conductive carbon coating, conductive metal coating, and conductive polymer coating.

[0059] In some embodiments, the conductive agent may 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, first, the positive electrode active material and the conductive agent are subjected to a first stirring to obtain a dry mixture, and the first stirring causes a tight entanglement between the two due to the anchoring effect. Next, the binder and solvent are mixed and a second stirring is performed to produce a binder liquid. This step enables effective dispersion of the binder in the solvent and avoids aggregation and solidification that would occur if the binder were directly mixed and stirred with other materials. Next, the dry mixture formed from the positive electrode active material and conductive agent is mixed with the binder liquid and a third stirring is performed to produce a primary paste. The third stirring effectively disperses the positive electrode active material and conductive agent in the binder liquid, and the binder in the binder liquid improves the stability of the paste due to its electrostatic and steric hindrance effects, reducing aggregation and sedimentation of the positive electrode active material and conductive agent. Finally, the binder and solvent are mixed with the primary paste and a fourth stirring is performed to obtain the positive electrode paste. In the fourth stirring, the binder added again coats the positive electrode active material and conductive agent, thereby stably dispersing the materials in the paste and delaying the gelation of the paste. In the fourth stirring, the solvent added again allows for effective adjustment of the viscosity of the paste at the time of shipment, preventing the viscosity from being too high at the time of shipment from affecting subsequent coating work.

[0063] The mass percentage of the binder used in the second stirring and the mass percentage of the binder used in the fourth stirring are 50% to 70% of the total mass of the binder used in the second stirring and 30% to 50% of the total mass of the binder used in the fourth stirring. If the mass of binder added in the second or fourth stirring is too much or too little, it will not be possible to effectively reduce the viscosity of the paste at the time of shipment and after standing for 24 hours, and the objective of mitigating the gelation of the paste will not be achieved.

[0064] Conventional methods for manufacturing cathode pastes have low compatibility and cannot adapt to differences in the weight-average molecular weight of binders in the paste, thus imposing high precision requirements on the materials. This invention reduces the viscosity of the cathode paste at the time of shipment and after 24 hours of standing by performing paste mixing in separate steps, mitigating the gelation phenomenon of the cathode paste. As a result, pastes with high weight-average molecular weight binders still have low viscosity at the time of shipment and after 24 hours of standing, and possess gelation prevention properties, improving the universality of the manufacturing method. The manufacturing method of this invention can be adapted not only to binders with low weight-average molecular weight but also to binders with high weight-average molecular weight, effectively mitigating the gelation phenomenon of different pastes, improving production efficiency, and helping to broaden the process window for paste coating.

[0065] In this specification, the term "process window" refers to the process range within which the quality of the product can be guaranteed, and includes, but is not limited to, a temperature range, a pressure range, or a length of storage time. To understand this, a wider process window generally indicates lower requirements for process precision.

[0066] In some embodiments, the binder comprises polyvinylidene fluoride having a weight-average molecular weight of at least 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, 1,500,000, 2,000,000, 2,500,000, 3,000,000, 3,500,000, 4,000,000, 4,500,000, 5,000,000, 5,500,000, 6,000,000, 6,500,000, 7,000,000, 7,500,000, and 8,000,000.

[0067] In this specification, the term "weight-average molecular weight" refers to the statistical average molecular weight of the polymer, calculated by the average mass of the polymer per unit weight.

[0068] Conventional paste mixing processes are difficult to adapt to binders with high weight-average molecular weight. Cathode pastes with high molecular weight binders produced by conventional methods tend to have high viscosity at the time of shipment, making it difficult to meet coating requirements and prone to serious gelation. The manufacturing method disclosed herein can be adapted to binders with a weight-average molecular weight of up to 8 million by adding the binder in separate steps and further combining the stirring speeds. As a result, the paste still has low viscosity at the time of shipment and viscosity after standing for 24 hours, possesses good gelation prevention properties, and can meet the needs of using high molecular weight binders.

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

[0070] In the third stirring stage, the dry mixture and binder liquid are first stirred at low speed to ensure that the dry mixture is sufficiently dispersed in the binder liquid, while simultaneously preventing excessive shearing of the dry mixture and ensuring the integrity of the positive electrode active material and conductive agent. Furthermore, the binder liquid that has undergone low-speed stirring covers the surfaces of the positive electrode active material and conductive agent, preventing excessive shearing of the positive electrode active material and conductive agent during subsequent high-speed stirring. By performing high-speed stirring after low-speed stirring, the viscosity of the paste can be reduced, and a positive electrode paste with low viscosity at the time of shipment can be provided for subsequent manufacturing.

[0071] In some embodiments, the orbital speed of the low-speed stirring in the third stirring is 15 revolutions / min to 25 revolutions / min, the rotational speed is 400 revolutions / min to 800 revolutions / min, and the stirring time is 5 minutes to 15 minutes.

[0072] In this specification, the term "rotational speed" refers to the speed at which an agitator rotates around its own axis.

[0073] In this specification, the term "orbital velocity" refers to the speed at which the agitator rotates around the tank containing the material.

[0074] In some embodiments, the orbital speed of the low-speed stirring in the third stirring can be selected from one of 15 revolutions / min, 20 revolutions / min, or 25 revolutions / min.

[0075] In some embodiments, the rotation speed for low-speed stirring in the third stirring can be selected from one of 400 rpm, 500 rpm, 600 rpm, 700 rpm, or 800 rpm.

[0076] In some embodiments, the stirring time for the low-speed stirring in the third stirring can be selected from 5 minutes, 10 minutes, or 15 minutes.

[0077] In some embodiments, the agitator is a planetary mixer. The operating principle of a planetary mixer is that, after the mixer is started, the planetary carrier rotates, causing the agitation shaft inside the box to rotate, revolving around the axis of the material cylinder while simultaneously rotating on its own at high speed, thereby subjecting the material to strong shearing and kneading action. The manufacturing method provided in this application is suitable for all types of planetary mixers.

[0078] If the orbital speed or rotational speed of the low-speed stirring in the third stirring stage is too low, or if the stirring time is too short, the dry mixture formed from the conductive agent and active material cannot be effectively dispersed in the binder liquid. This results in excessively high viscosity of the paste at the time of shipment and after 24 hours of standing, making the paste prone to gel formation and resulting in low paste stability. If the orbital speed or rotational speed of the low-speed stirring in the third stirring stage is too high, or if the stirring time is too long, it will not significantly improve the viscosity of the paste at the time of shipment, the viscosity after 24 hours of standing, or the gelation phenomenon of the paste, and will also lead to wasted energy and increased manufacturing costs.

[0079] From the above, by controlling the orbital speed, rotational speed, and stirring time of the low-speed stirring in the third stirring stage to an appropriate range, the paste has low viscosity at the time of shipment, low viscosity after standing for 24 hours, and excellent gelation prevention properties, which is advantageous in improving the coating properties, processability, and stability of the paste.

[0080] In some embodiments, the orbital speed of high-speed stirring in the third stirring is 20 revolutions / min to 30 revolutions / min, the rotational speed is 1000 revolutions / min to 1300 revolutions / min, and the stirring time is 50 minutes to 80 minutes.

[0081] In some embodiments, the orbital speed of high-speed stirring in the third stirring can be selected from one of 20 revolutions / min, 25 revolutions / min, or 30 revolutions / min.

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

[0083] In some embodiments, the stirring time for high-speed stirring in the third stirring can be selected from 50 minutes, 60 minutes, 70 minutes, or 80 minutes.

[0084] If the orbital speed or rotational speed of the high-speed stirring in the third stirring stage is too low, or if the stirring time is too short, the primary paste cannot be strongly sheared, resulting in excessively high viscosity of the paste at the time of shipment and after 24 hours of standing, making the paste prone to gel formation and resulting in low paste stability. If the orbital speed or rotational speed of the high-speed stirring in the third stirring stage is too high, or if the stirring time is too long, it will not be possible to significantly improve the viscosity of the paste at the time of shipment, the viscosity after 24 hours of standing, or the gelation phenomenon of the paste, and will result in wasted energy and reduced production efficiency.

[0085] From the above, by controlling the orbital speed, rotational speed, and stirring time of high-speed stirring in the third stirring stage to an appropriate range, the paste has low viscosity at the time of shipment, low viscosity after standing for 24 hours, and excellent gelation prevention properties, which is advantageous in improving the coating properties, processability, and stability of the paste.

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

[0087] By controlling the rotation speed of the first stirring to zero, the shear force of the first stirring can be minimized, significantly reducing the possibility of excessive crushing of the active material and conductive agent. This ensures that the positive electrode active material and conductive agent have a certain granularity and specific surface area, which helps to improve the dispersion effect of the positive electrode active material and conductive agent. Furthermore, it reduces the viscosity of the paste after standing for 24 hours, mitigates the gelation phenomenon of the paste, and improves the stability of the paste.

[0088] In some embodiments, the orbital speed of the first stirring is 20 revolutions / min to 30 revolutions / min.

[0089] In some embodiments, the orbital speed of the first stirring can be selected from one of 20 revolutions / min, 25 revolutions / min, or 30 revolutions / min.

[0090] If the orbital speed of the first stirring is too low, the positive electrode active material and conductive agent cannot be effectively mixed, resulting in excessively high viscosity of the paste at the time of shipment and after 24 hours of standing, making the paste prone to gel formation and resulting in low paste stability. If the orbital speed of the first stirring is too high, it will not significantly improve the viscosity of the paste at the time of shipment, the viscosity after 24 hours of standing, or the gelation phenomenon of the paste, and will instead lead to wasted energy and increased production costs.

[0091] By controlling the orbital 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 exhibits gelation prevention properties, which is advantageous in improving the coating properties, processability, and stability of the paste.

[0092] In some embodiments, the stirring time for the first stirring is 5 to 20 minutes. In some embodiments, the stirring time for the first stirring can be selected from 5 minutes, 10 minutes, 15 minutes, or 20 minutes.

[0093] If the stirring time in the first stirring stage is too short, the positive electrode active material and conductive agent cannot be effectively mixed, resulting in excessively high viscosity of the paste at the time of shipment and after 24 hours of standing, making the paste prone to gel formation and resulting in low paste stability. If the stirring time in the first stirring stage is too long, the viscosity of the paste at the time of shipment, the viscosity after 24 hours of standing, and the gelation phenomenon of the paste cannot be significantly improved, leading to wasted energy and decreased 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 possesses gelation prevention properties, which is advantageous in improving the coating properties, processability, and stability of the paste.

[0095] In some embodiments, the stirring time for the second stirring is 50 to 80 minutes. In some embodiments, the stirring time for the second stirring can be selected from 50 minutes, 60 minutes, 70 minutes, or 80 minutes.

[0096] If the stirring time in the second stirring stage is too short, the binder and solvent cannot be effectively mixed, resulting in excessively high viscosity of the paste at the time of shipment and after 24 hours of standing, making the paste prone to gel formation and resulting in low paste stability. If the stirring time in the second stirring stage is too long, the viscosity of the paste at the time of shipment, the viscosity after 24 hours of standing, and the gelation phenomenon of the paste cannot be significantly improved, leading to wasted energy and decreased 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 possesses gelation prevention properties, which is advantageous in improving the coating properties, processability, and stability of the paste.

[0098] In some embodiments, the orbital speed of the second stirring is 25 revolutions / min to 40 revolutions / min. In some embodiments, the orbital speed of the second stirring can be selected from any one of 25 revolutions / min, 30 revolutions / min, 35 revolutions / min, or 40 revolutions / min.

[0099] If the orbital speed of the second stirring is too low, the binder and solvent cannot be effectively mixed, resulting in excessively high viscosity of the paste both at the time of shipment and after 24 hours of standing, making the paste prone to gel formation and resulting in low paste stability. If the orbital speed of the second stirring is too high, the paste is also prone to gel formation.

[0100] By controlling the orbital speed of the second stirring within an appropriate range, the paste has low viscosity upon shipment and low viscosity after standing for 24 hours, which is advantageous in simultaneously mitigating the gelling state of the paste, improving the stability of the paste 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, or 1300 rpm.

[0102] If the orbital speed of the second stirring is too low, the binder and solvent cannot be effectively mixed, resulting in excessively high viscosity of the paste at the time of shipment and after 24 hours of standing, making the paste prone to gel formation and resulting in low paste stability. If the orbital speed of the second stirring is too high, it will not significantly improve the viscosity of the paste at the time of shipment, the viscosity after 24 hours of standing, or the gelation phenomenon of the paste, and will instead lead to 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 exhibits gelation prevention properties, which is advantageous in improving the coating properties, processability, and stability of the paste.

[0104] In some embodiments, the stirring time for the fourth stirring is 60 to 90 minutes. In some embodiments, the stirring time for the fourth stirring can be selected from 60 minutes, 70 minutes, 80 minutes, or 90 minutes.

[0105] If the stirring time in the fourth stirring stage is too short, the binder and solvent cannot be effectively mixed with the primary paste, resulting in excessively high viscosity of the paste both at the time of shipment and after 24 hours of standing, making the paste prone to gel formation and resulting in low paste stability. If the stirring time in the fourth stirring stage is too long, the positive electrode active material and conductive agent become easily crushed, making the paste prone to gel formation.

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

[0107] In some embodiments, the orbital speed of the fourth stirring is 25 revolutions / min to 40 revolutions / min. In some embodiments, the orbital speed of the fourth stirring can be selected from any one of 25 revolutions / min, 30 revolutions / min, 35 revolutions / min, or 40 revolutions / min.

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

[0109] By controlling the orbital speed of the fourth stirring within an appropriate range, the paste has low viscosity upon shipment and low viscosity after standing for 24 hours, while simultaneously mitigating the gelling state of the paste, improving paste stability and widening the process window.

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

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

[0112] By controlling the rotation speed of the fourth stirring within an appropriate range, the paste has low viscosity upon shipment and low viscosity after standing for 24 hours, while simultaneously mitigating the gelling state of the paste, improving paste stability and widening the process window.

[0113] In some embodiments, 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.

[0114] The solid content and viscosity of the positive electrode paste can both be measured by any method known in the art. Viscosity can be measured using a rotational viscometer, and solid content can be measured by measuring the weight of the paste before and after removing the water.

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

[0116] In one embodiment, 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, 1 You can choose one of the following pressure levels: 9000mPa·s, 20000mPa·s, 21000mPa·s, 22000mPa·s, 23000mPa·s, 24000mPa·s, 25000mPa·s, 26000mPa·s, 27000mPa·s, 28000mPa·s, 29000mPa·s, 30000mPa·s, or 31000mPa·s.

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

[0118] In some embodiments, the mass percentage of the solvent used in the second stirring is 35% to 45% of 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, and the mass percentage of the solvent used in the fourth stirring is 4% to 10%.

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

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

[0121] The positive electrode paste within the above range not only exhibits good processability, but also results in superior electrical and chemical properties for the resulting positive electrode sheet after molding.

[0122] [Positive electrode paste] In one embodiment of the present invention, a positive electrode paste is provided, wherein the solid content of the positive electrode paste is 65% to 70%, the initial viscosity of the positive electrode paste is 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] Initial viscosity refers to the viscosity at the time of shipment, immediately after the placement of the positive electrode paste is complete.

[0124] In some embodiments, the positive electrode paste is manufactured by the method for manufacturing the positive electrode paste in any of the embodiments described above.

[0125] In some embodiments, after standing for 24 hours, the viscosity of the positive electrode paste does not exceed 48,000 mPa·s, 45,000 mPa·s, 41,000 mPa·s, 35,000 mPa·s, 31,000 mPa·s, or 26,000 mPa·s.

[0126] The paste formed by the manufacturing method of this invention has a high solid content, appropriate viscosity, and excellent processability, while also having excellent shelf life.

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

[0128] One embodiment of the present invention provides a secondary battery.

[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 a positive electrode paste produced by the manufacturing method of any embodiment.

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

[0131] During the charging and discharging process of a battery, active ions reciprocate between the positive and negative electrode sheets, being inserted and removed. The electrolyte plays a role in conducting ions between the positive and negative electrode sheets. A separator is placed between the positive and negative electrode sheets and primarily serves to prevent short circuits between the positive and negative electrodes while simultaneously 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 placed on at least one surface of the positive electrode current collector, the positive electrode film layer being manufactured from a positive electrode paste manufactured by the method for manufacturing a positive electrode paste in any embodiment of the present application or from a positive electrode paste in any embodiment.

[0133] For example, the positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode film layer is provided on one or both of the two opposing surfaces of the positive electrode current collector.

[0134] In some embodiments, a metal foil or a composite current collector may be used as the positive electrode current collector. For example, an aluminum foil may be used as the metal foil. The composite current collector may comprise a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by depositing a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy) onto a polymer material substrate (such as substrates of polypropylene (PP), polyethylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0135] In some embodiments, the positive electrode active material may be a positive electrode active material for batteries known in the art. By way of example, the positive electrode active material may comprise at least one selected from lithium-containing phosphate with olivine structure, lithium transition metal oxides and respective modified compounds thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a positive electrode active material for a battery may also be used. Only one of these positive electrode active materials may be used alone, or two or more of them may be used in combination. Herein, examples of lithium transition metal oxides include lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (may be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (may be abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (may be abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2O2(NCM 622 (It may also be abbreviated as LiNi) 0.8 Co 0.1 Mn 0.1 O2(NCM 811 (May be abbreviated as LiNi) Lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 It may contain, but is not limited to, at least one of O2) and its modified compounds. Examples of lithium-containing phosphates with an olivine structure include, but is not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (also called LFP)), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), composite materials of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.

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

[0137] In some embodiments, the positive electrode film layer may further selectively contain a conductive agent. As an example, the conductive agent may include 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 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 positive electrode paste manufacturing method of any embodiment of this application. The manufactured positive electrode paste is then applied to a positive electrode current collector, and a positive electrode sheet can be obtained through processes such as drying and cold pressing.

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

[0140] For example, the negative electrode current collector has two opposing surfaces in its own thickness direction, and the negative electrode film layer is provided on one or both of the two opposing surfaces of the negative electrode current collector.

[0141] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. For example, copper foil can be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys) on a polymer material substrate (for example, a substrate such as 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 negative electrode active material for batteries known in the art. For example, the negative electrode active material may include at least one material from among artificial graphite, natural graphite, soft carbon, hard carbon, silicone-based materials, tin-based materials, and lithium titanate. The silicone-based material may be selected from at least one of elemental silicone, silicone oxide, silicone-carbon composite, silicone-nitrogen composite, and silicone alloy. The tin-based material may be selected from at least one of elemental tin, tin oxide, and tin alloy. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may be used. These negative electrode active materials may be used individually or in combination of two or more.

[0143] In some embodiments, the negative electrode film layer further selectively comprises a binder. The binder 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 selectively includes a conductive agent. The conductive agent 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 film layer further selectively includes other additives, such as thickeners (e.g., sodium carboxymethylcellulose (CMC-Na)).

[0146] In some embodiments, a negative electrode sheet can be manufactured by the following method. 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. The negative electrode paste is then applied to a negative electrode current collector, and the negative electrode sheet can be obtained through processes such as drying and cold pressing.

[0147] [Electrolyte] The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. This application does not specifically limit the type of electrolyte, and it can be selected according to the requirements. For example, the electrolyte may be a liquid, a gel, or all-solid.

[0148] In some embodiments, an electrolyte solution is used as the electrolyte. The electrolyte solution comprises an electrolyte salt and a solvent.

[0149] In some embodiments, the electrolyte salt may be selected 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 selected 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 further selectively includes additives. For example, the additives may include negative electrode film forming additives, positive electrode film forming additives, and may also include additives that can improve some of the battery's performance characteristics, such as additives that improve the battery's overcharge performance, or additives that improve the battery's high-temperature or low-temperature performance.

[0152] [Separator] In some embodiments, the secondary battery further includes a separator. This application is not particularly limited to the type of separator, and any known porous separator having good chemical and mechanical stability may be selected.

[0153] In some embodiments, the material of the separator may be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of each layer may be the same or different, and is not particularly limited.

[0154] In some embodiments, the positive electrode sheet, negative electrode sheet, and separator can be manufactured into an electrode assembly by a winding process or a lamination process.

[0155] In some embodiments, the secondary battery may include an outer casing. This casing may be used to package the electrode assembly and electrolyte.

[0156] In some embodiments, the casing of the secondary battery may be a rigid case, such as a rigid plastic case, an aluminum case, or a steel case. The casing of the secondary battery may also be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0157] This 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 a secondary battery 5 with a rectangular structure as an example.

[0158] In some embodiments, referring to Figure 2, the casing may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates enclosing and forming a housing cavity. The case 51 has an opening that communicates with the housing cavity, and the cover plate 53 can cover the opening and seal the housing cavity. The positive electrode sheet, negative electrode sheet and separator can form an electrode assembly 52 by a winding process or a lamination process. The electrode assembly 52 is packaged within the housing cavity. The 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 specifically select them according to their 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 depending on the application and capacity of the battery module.

[0160] Figure 3 shows an example of a battery module 4. Referring to Figure 3, in the battery module 4, multiple secondary batteries 5 may be installed in a sequential arrangement along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, these multiple secondary batteries 5 may be fixed in place with fasteners.

[0161] Selectively, the battery module 4 may further include a housing having a housing space, in which a plurality of secondary batteries 5 are housed.

[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 depending on the application and capacity of the battery pack.

[0163] Figures 4 and 5 show an example of a battery pack 1. Referring to Figures 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, the upper housing 2 being covered by the lower housing 3 and forming a sealed space for housing the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0164] The present application further provides a power consumption device comprising at least one of a secondary battery, battery module, or battery pack as described herein. The secondary battery, battery module, or battery pack may be used as a power source for the power consumption device or as an energy storage unit for the power consumption device. The power consumption 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 and satellites, energy storage systems, etc.

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

[0166] Figure 6 shows an example of a power consumption device. This power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the demand for high output and high energy density of the secondary battery in this power consumption device, a battery pack or battery module can be used.

[0167] Other examples of such devices may include mobile phones, tablet computers, and laptop computers. These devices generally require to be lightweight and can use rechargeable batteries as a power source.

[0168] Examples The following describes embodiments of this application. The embodiments described below are illustrative and are for interpretive purposes only and should not be considered limitations thereto. Where no specific technical or condition is specified in the embodiments, the techniques or conditions described in the literature in the art or in accordance with product specifications shall apply. Unless the manufacturer is specified for the reagents and equipment used, they are all common commercially available products.

[0169] 1. Preparation method Example 1 1) Manufacturing of positive electrode paste First stirring: 25 kg of conductive carbon black and 1200 kg of lithium iron phosphate were stirred and mixed in a double planetary mixer for 15 minutes, with an orbital speed of 25 revolutions / minute and a rotational 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 were mixed and stirred at an orbital speed of 25 revolutions / min and a rotational speed of 1200 revolutions / min, for a stirring time of 60 minutes to obtain the binder liquid.

[0171] Third stirring: Add the dry mixture to the binder solution and stir, stirring for 10 minutes at an orbital speed of 20 revolutions / min and a rotational speed of 600 revolutions / min, and then stirring for another 70 minutes at an orbital speed of 25 revolutions / min and a rotational speed of 1200 revolutions / min to obtain the primary paste.

[0172] Fourth stirring: 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 are mixed and stirred. The mixture is stirred for 70 minutes at an orbital speed of 30 revolutions / min and a rotational speed of 1200 revolutions / min to obtain a cathode paste with a viscosity of 18000 mPa·s and a solid content of 68%.

[0173] Examples 2-3 The manufacturing method was substantially the same as in Example 1, the only difference being the adjustment of the mass percentage of the binder during the second stirring. The specific parameters are shown in Table 1.

[0174] Examples 4-9 The manufacturing method was substantially the same as in Example 1, the only difference being the adjustment of the weight-average molecular weight of the binder polyvinylidene fluoride. The specific parameters are shown in Table 1.

[0175] Examples 10-67 The manufacturing method is substantially the same as in Example 1, the only difference being the adjustment of the stirring parameters, which are shown in Table 1.

[0176] Comparative Example 1 1) 8 kg of conductive carbon black and 1200 kg of lithium iron phosphate were mixed together in a double planetary mixer for 15 minutes, with an orbital speed of 25 revolutions / minute and a rotational 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 were mixed and stirred at an orbital speed of 25 revolutions / min and a rotational speed of 1200 revolutions / min, for a stirring time of 60 minutes to obtain the binder liquid.

[0178] 3) Add the dry mixture to the binder solution and first stir at low speed for 200 minutes, with an orbital speed of 25 revolutions / minute and a rotational speed of 1200 revolutions / minute. Next, stir at high speed for 60 minutes, with an orbital speed of 30 revolutions / minute and a rotational speed of 1300 revolutions / minute to obtain the positive electrode paste.

[0179] Comparative Examples 2-5 The manufacturing method was substantially the same as in Comparative Example 1, the only difference being the adjustment of the weight-average molecular weight of the binder polyvinylidene fluoride. The specific parameters are shown in Table 1.

[0180] Comparative Example 6 1) Mix and stir 18 kg of polyvinylidene fluoride binder with a weight-average molecular weight of 1.8 million and 560 kg of N-methyl-2-pyrrolidone at a rotational speed of 25 revolutions / min and a rotational speed of 1200 revolutions / min for 60 minutes to obtain the binder solution.

[0181] 2) Add 1200 kg of lithium iron phosphate to the binder solution and mix and stir for 60 minutes, with an orbital speed of 25 revolutions / minute and a rotational speed of 1200 revolutions / minute to obtain a primary paste.

[0182] 3) Add 8 kg of conductive carbon black to the primary paste and mix and stir for 140 minutes, with an orbital speed of 30 revolutions / minute and a rotational speed of 1200 revolutions / minute to obtain the positive electrode paste.

[0183] Comparative Examples 7-10 The manufacturing method was substantially the same as that of Comparative Example 6, the only difference being the adjustment of the weight-average molecular weight of the polyvinylidene fluoride binder. The specific parameters are shown in Table 1.

[0184] Comparative Examples 11-12 The manufacturing method was substantially the same as in Example 1, the only difference being the adjustment of the mass percentage of the binder during the second stirring. The specific parameters are shown in Table 1.

[0185] 2. Testing the properties of the paste 1. Viscosity test of paste at the time of shipment. The manufactured cathode paste is allowed to stand for 10 minutes before shipment. The viscosity value measured first using a Dveslvtjo rotational viscometer (BROOKFIELD) is recorded as the shipment viscosity. Test conditions: 25°C, rotation speed 12 revolutions / minute. 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 the paste has been left to stand for 24 hours. The viscosity of the paste was re-tested after standing for 24 hours. The viscosity value measured using a Dveslvtjo rotational viscometer (BROOKFIELD) was recorded as the 24-hour viscosity. Test conditions: 25°C, rotation speed 12 revolutions / minute. 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. Gelation state test after the paste has been left to stand for 24 hours. After letting the paste stand for 24 hours, the paste in the beaker is lifted out with a steel ruler, and the gelation state of the paste is determined from its fluid state.

[0188] A non-gelling state is characterized by the paste flowing naturally and continuously, advection across the surface of the steel scale, and the absence of aggregation.

[0189] A state of mild gelation is characterized by the paste flowing naturally and continuously, but the fluid being thin, and the paste spreading essentially flat on the surface of the steel scale, with only slight lumps present.

[0190] A moderate gelling state is characterized by the paste dripping spontaneously, with occasional interruptions, discontinuous flow, and the paste not spreading evenly across the steel scale surface, but rather exhibiting clear clumping.

[0191] Severe gelling occurs when the paste cannot flow off but falls as a lump or remains on the steel scale without flowing away.

[0192] 4. Test for the solid content of the paste. The aluminum foil was taken and weighed using a moisture meter, and the result was determined to be M0. The display was then cleared. The moisture meter is an MOC-120H.

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

[0194] Close the equipment, start drying, and after completion, record the weighing data and set it as M2, and calculate the solid content, which is (M2-M0) / (M1-M0).

[0195] 3. Analysis of the test results of each example and comparative example. The positive electrode pastes for each example and comparative example were manufactured according to the method described above, 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 manufactured using the paste manufacturing method disclosed in this application, and all include a first, second, third, and fourth stirring. In the first stirring, the positive electrode active material and conductive agent are mixed and stirred to produce a dry mixture; in the second stirring, the binder and 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; and 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, and the mass percentage of the binder used in the second stirring is 50% to 70% of the total mass of the binders used in the second and fourth stirrings, and the mass percentage of the binder used in the fourth stirring is 30% to 50%.

[0198] As can be seen by comparing Examples 1-9 and Comparative Examples 1-10, the paste manufacturing method of this disclosure is versatile and can be applied to pastes containing polyvinylidene fluoride binders with a weight-average molecular weight of 200,000 to 8,000,000, and is universally applicable to both low molecular weight and high molecular weight binders.

[0199] As can be seen from the comparative examples, none of the conventional manufacturing processes can improve the gelation state of a binder with a weight-average molecular weight of 1.8 million. The manufacturing method disclosed herein allows pastes containing binders with a weight-average molecular weight of 8 million to still have low viscosity at shipment and good gelation prevention properties, meeting the needs of next-generation high molecular weight binders.

[0200] As can be seen by comparing Examples 1-3 with Comparative Examples 11-12, by controlling the proportion of binder added in the first stirring to 50%-70% of the total binder mass, the viscosity of the paste at the time of shipment can be reduced, effectively mitigating gelation of the paste and widening the process window for paste coating.

[0201] A comparison of Examples 1, 5-9, and 4 shows that by controlling the weight-average molecular weight of the polyvinylidene fluoride binder to 800,000-8,000,000, no significant changes were observed in the viscosity of the paste at the time of shipment, the viscosity after standing for 24 hours, or the gelation phenomenon of the paste, while simultaneously meeting the requirements for adhesion to polar sheets.

[0202] As can be seen by comparing Examples 27-29 with Example 26, and Examples 31-33 with Example 30, by first performing low-speed stirring in the third stirring stage, followed by high-speed stirring, the viscosity of the paste at the time of shipment and the viscosity after the paste has been left to stand for 24 hours can be effectively reduced, gelling of the paste is mitigated, and the coating properties and processability of the paste are improved.

[0203] As can be seen by comparing Examples 1, 11-12 and Example 10, controlling the stirring time of low-speed stirring in the third stirring to 5 to 15 minutes can reduce the viscosity of the paste at the time of shipment and the viscosity after standing for 24 hours, mitigating paste gelation and widening the process window for paste coating. As can be seen by comparing Examples 1, 11-12 and Example 13, controlling the stirring time of low-speed stirring in the third stirring to 5 to 15 minutes can achieve both quality and efficiency in paste mixing, reducing viscosity at the time of shipment and mitigating paste gelation.

[0204] As can be seen by comparing Examples 1, 15-16 and Example 14, controlling the orbital speed of low-speed stirring in the third stirring to 15 revolutions / min to 25 revolutions / min can reduce the viscosity of the paste at the time of shipment and after standing for 24 hours, mitigating paste gelation and widening the process window for paste coating. As can be seen by comparing Examples 1, 15-16 and Example 17, controlling the orbital speed of low-speed stirring in the third stirring to 15 revolutions / min to 25 revolutions / min can balance paste mixing quality and cost, reduce viscosity at the time of shipment, and mitigate paste gelation.

[0205] As can be seen by comparing Examples 1, 19-20 and Example 18, controlling the rotation speed of the low-speed stirring in the third stirring to 400 rpm to 800 rpm can reduce the viscosity of the paste at the time of shipment and after standing for 24 hours, mitigating gelation of the paste, improving the shelf life of the paste, and widening the process window for paste coating. As can be seen by comparing Examples 1, 19-20 and Example 21, setting the rotation speed of the low-speed stirring in the third stirring to 400 rpm to 800 rpm allows for a balance between paste mixing quality and cost, reducing viscosity at the time of shipment and mitigating gelation of the paste.

[0206] As can be seen by comparing Examples 1, 23-24 and Example 22, controlling the stirring time of high-speed stirring in the third stirring to 50-80 minutes can reduce the viscosity of the paste at the time of shipment and the viscosity after standing for 24 hours, mitigating gelation of the paste, improving the shelf life of the paste, and widening the process window for paste coating. As can be seen by comparing Examples 1, 23-24 and Example 25, controlling the stirring time of high-speed stirring in the third stirring to 50-80 minutes can achieve both quality and efficiency in paste mixing, reducing viscosity at the time of shipment and mitigating gelation of the paste.

[0207] As can be seen by comparing Examples 1, 27-28 and Example 26, controlling the orbital speed of high-speed stirring in the third stirring to 20 revolutions / min to 30 revolutions / min can reduce the viscosity of the paste at the time of shipment and after standing for 24 hours, mitigating paste gelation, improving paste shelf life, and widening the process window for paste coating. As can be seen by comparing Examples 1, 15-16 and Example 17, controlling the orbital speed of low-speed stirring in the third stirring to 15 revolutions / min to 25 revolutions / min can balance paste mixing quality and cost, reducing viscosity at the time of shipment and mitigating paste gelation.

[0208] As can be seen by comparing Examples 1, 31-32 and Example 30, controlling the rotation speed of high-speed stirring in the third 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, mitigating gelation of the paste, improving the shelf life of the paste, and widening the process window for paste coating. As can be seen by comparing Examples 1, 31-32 and Example 33, controlling the rotation speed of high-speed stirring in the third stirring to 1000 rpm to 1300 rpm can balance the quality and cost of paste mixing, reduce viscosity at the time of shipment, and mitigate gelation of the paste.

[0209] As can be seen by comparing Example 1 with Examples 34-35, controlling the rotation speed of the first stirring to 0 can reduce the viscosity of the paste after it has been left to stand for 24 hours, mitigating the gelation phenomenon of the paste, improving the stability of the paste, and widening the process window.

[0210] As can be seen by comparing Examples 1, 37-38 and 36, controlling the stirring time of the first stirring to 5 to 20 minutes can reduce the viscosity of the paste at the time of shipment and after standing for 24 hours, mitigating the gelation phenomenon of the paste, improving the stability of the paste, and widening the process window. As can be seen by comparing Examples 1, 37-38 and 39, controlling the stirring time of the first stirring to 5 to 20 minutes can achieve both quality and efficiency in paste mixing, reducing the viscosity at the time of shipment and mitigating the gelation of the paste.

[0211] As can be seen by comparing Examples 1, 41-42 and 40, controlling the orbital speed of the first stirring to 20-30 revolutions / min can reduce the viscosity of the paste at the time of shipment and after standing for 24 hours, mitigating the gelation phenomenon of the paste, improving the stability of the paste, and widening the process window. As can be seen by comparing Examples 1, 41-42 and 43, controlling the orbital speed of the first stirring to 20-30 revolutions / min can balance the quality and cost of paste mixing, reduce the viscosity at the time of shipment, and mitigate the gelation of the paste.

[0212] As can be seen by comparing Examples 1, 45-46 and 44, controlling the stirring time of the second stirring to 50-80 minutes can reduce the viscosity of the paste at the time of shipment and after standing for 24 hours, mitigating the gelation phenomenon of the paste, improving the stability of the paste, and widening the process window. As can be seen by comparing Examples 1, 45-46 and 47, controlling the stirring time of the second stirring to 50-80 minutes can achieve both quality and efficiency in paste mixing, reducing the viscosity at the time of shipment and mitigating the gelation of the paste.

[0213] As can be seen by comparing Examples 1, 49-50 and 48, controlling the orbital speed of the second stirring to 25 revolutions / min to 40 revolutions / min can reduce the viscosity of the paste at the time of shipment and after standing for 24 hours, mitigating the gelation phenomenon of the paste, improving the stability of the paste, and widening the process window. As can be seen by comparing Examples 1, 49-50 and 51, controlling the orbital speed of the second stirring to 25 revolutions / min to 40 revolutions / min can mitigate the gelation of the paste, improving the stability of the paste, and widening the process window.

[0214] As can be seen by comparing Examples 1, 53-54 and 52, controlling the rotation speed of the second stirrer to 1000 rpm to 1300 rpm can reduce the viscosity of the paste at the time of shipment and after standing for 24 hours, mitigating the gelation phenomenon of the paste, improving the stability of the paste, and widening the process window. As can be seen by comparing Examples 1, 53-54 and 55, controlling the rotation speed of the second stirrer to 1000 rpm to 1300 rpm can balance the quality and cost of paste mixing, reduce the viscosity at the time of shipment, and mitigate the gelation of the paste.

[0215] As can be seen by comparing Examples 1, 57-58 and 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, mitigating the gelation phenomenon of the paste, improving the stability of the paste, and widening the process window. As can be seen by comparing Examples 1, 57-58 and 59, controlling the stirring time of the fourth stirring to 60-90 minutes can mitigate the gelation of the paste, improving the stability of the paste, and widening the process window.

[0216] As can be seen by comparing Examples 1, 61-62 and 60, controlling the orbital speed of the fourth stirrer to 25 revolutions / min to 40 revolutions / min can reduce the viscosity of the paste at the time of shipment and after standing for 24 hours, mitigating the gelation phenomenon of the paste, improving the stability of the paste, and widening the process window. As can be seen by comparing Examples 1, 61-62 and 63, controlling the orbital speed of the fourth stirrer to 25 revolutions / min to 40 revolutions / min can mitigate the gelation of the paste, improving the stability of the paste, and widening the process window.

[0217] As can be seen by comparing Examples 1, 65-66 and 64, controlling the rotation speed of the fourth stirrer to 1000 rpm to 1300 rpm can reduce the viscosity of the paste at the time of shipment and after standing for 24 hours, mitigating the gelation phenomenon of the paste, improving the stability of the paste, and widening the process window. As can be seen by comparing Examples 1, 65-66 and 67, controlling the rotation speed of the fourth stirrer to 1000 rpm to 1300 rpm can mitigate the gelation of the paste, improving the stability of the paste, and widening the process window.

[0218] As can be seen from the examples, the viscosity of the positive electrode paste disclosed herein, having a solid content of 65% to 70%, is 6000 mPa·s to 31000 mPa·s, and the positive electrode paste has good coating 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, conductive agent, binder used in the second stirring, and binder used in the fourth stirring.

[0220] As can be seen from the examples, the solid 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] Furthermore, this application is not limited to the embodiments described above. The embodiments described above are merely examples, and any embodiment that has substantially the same configuration as the technical idea and produces the same effects within the scope of the technical proposal of this application is included within the scope of the technical application. In addition, other forms that are constructed by adding various modifications to the embodiments that a person skilled in the art could conceive of, and by combining some of the components of the embodiments, are also included within the scope of this application, without departing from the spirit of this application. Preferred embodiments of the present invention are as follows: [1] A method for manufacturing positive electrode paste, This includes a first stirring, a second stirring, a third stirring, and a fourth stirring, In the first stirring step, the positive electrode active material and the conductive agent are mixed and stirred to produce a dry mixture. In the second stirring step, the binder and solvent are mixed and stirred to produce a binder solution. 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, solvent, and primary paste are mixed and stirred to produce a positive electrode paste. A method for producing a positive electrode paste, characterized in that the binder and solvent used in the second stirring are the same as those used in the fourth stirring, and the mass percentage of the binder used in the second stirring is 50% to 70% of the total mass of the binders used in the second and fourth stirrings, and the mass percentage of the binder used in the fourth stirring is 30% to 50%. [2] The method for producing a positive electrode paste according to [1], characterized in that the binder contains at least polyvinylidene fluoride having a weight-average molecular weight of 800,000 to 8,000,000. [3] The method for producing a positive electrode paste according to [1] or [2], characterized in that low-speed stirring is performed first in the third stirring, followed by high-speed stirring. [4] The method for producing a positive electrode paste according to [3], characterized in that the orbital speed of the low-speed stirring in the third stirring is 15 revolutions / min to 25 revolutions / min, the rotational speed is 400 revolutions / min to 800 revolutions / min, and the stirring time is 5 minutes to 15 minutes. [5] The method for producing a positive electrode paste according to [3] or [4], characterized in that the orbital speed of high-speed stirring in the third stirring is 20 revolutions / min to 30 revolutions / min, the rotational speed is 1000 revolutions / min to 1300 revolutions / min, and the stirring time is 50 minutes to 80 minutes. [6] A method for producing a positive electrode paste according to any one of the above [1] to [5], characterized in that the rotation speed of the first stirring is 0. [7] A method for producing a positive electrode paste according to any one of the above [1] to [6], characterized in that the orbital speed of the first stirring is 20 revolutions / min to 30 revolutions / min. [8] A method for producing a positive electrode paste according to any one of the above [1] to [7], characterized in that the stirring time for the first stirring is 5 minutes to 20 minutes. [9] A method for producing a positive electrode paste according to any one of the above items [1] to [8], characterized in that the stirring time for the second stirring is 50 minutes to 80 minutes.

[10] A method for producing a positive electrode paste according to any one of the above [1] to [9], characterized in that the orbital speed of the second stirring is 25 revolutions / min to 40 revolutions / min.

[11] The method for producing a positive electrode paste according to any one of the above [1] to

[10] , characterized in that the rotation speed of the second stirring is 1000 revolutions / min to 1300 revolutions / min.

[12] A method for producing a positive electrode paste according to any one of the above items [1] to

[11] , characterized in that the stirring time for the fourth stirring is 60 minutes to 90 minutes.

[13] A method for producing a positive electrode paste according to any one of the above [1] to

[12] , characterized in that the orbital speed of the fourth stirring is 25 revolutions / min to 40 revolutions / min.

[14] A method for producing a positive electrode paste according to any one of the above items [1] to

[13] , characterized in that the rotation speed of the fourth stirring is 1000 revolutions / min to 1300 revolutions / min.

[15] A method for producing a positive electrode paste according to any one of the above [1] to

[14] , characterized in that 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.

[16] A method for producing a positive electrode paste according to any one of the above [1] to

[15] , characterized in that 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% 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.

[17] A method for producing a positive electrode paste according to any one of the above [1] to

[16] , characterized in that the ratio of the mass of the positive electrode active material, the total mass of the binder, and the mass of the conductive agent in the positive electrode paste is (88-96):(2-4):(2-8).

[18] A method for producing a positive electrode paste according to any one of the above [1] to

[17] , characterized in that the positive electrode active material is at least one of lithium iron phosphate and its modifying material, lithium nickel cobalt manganese oxide and its modifying material, and the modifying material is produced by one or more modification methods of doping, conductive carbon coating, conductive metal coating, and conductive polymer coating.

[19] A method for producing a positive electrode paste according to any one of the above [1] to

[18] , characterized in that 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 manufactured by the method for manufacturing a positive electrode paste described in any one of the above items [1] to

[19] .

[21] The positive electrode paste according to

[20] , characterized in that the solid content is 65% to 70%, the initial viscosity is 6,000 to 31,000 mPa·s, and after standing for 24 hours, the viscosity 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 a positive electrode paste manufactured by the method for manufacturing a positive electrode paste described in any one of the above items [1] to

[19] , or a positive electrode paste described in

[20] or

[21] .

[23] The secondary battery described in

[22] , characterized in that it is one of a lithium-ion battery, a sodium-ion battery, a magnesium-ion battery, or a potassium-ion battery.

[24] A battery module characterized by including the secondary battery described in

[22] or

[23] above.

[25] A battery pack characterized by comprising at least one of the secondary battery described in

[22] or

[23] above and the battery module described in

[24] above.

[26] A power consumption device characterized by comprising at least one selected from the secondary battery described in

[22] or

[23] , the battery module described in

[24] , or the battery pack described in

[25] . [Explanation of Symbols]

[0222] 1 Battery pack, 2 Upper casing, 3 Lower casing, 4 Battery module, 5 Rechargeable battery, 51 Case, 52 Electrode assembly, 53 Cover plate

Claims

1. A method for manufacturing positive electrode paste, This includes 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 are mixed and stirred to produce a dry mixture. In the second stirring step, the binder and solvent are mixed and stirred to produce a binder solution. 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, 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, and the mass percentage of the binder used in the second stirring is 50% to 70% of the total mass of the binders used in the second and fourth stirrings, and the mass percentage of the binder used in the fourth stirring is 30% to 50%. In the third stirring stage, low-speed stirring is performed first, followed by high-speed stirring. In the third stirring stage, the orbital speed is 15 to 25 revolutions per minute, the rotational speed is 400 to 800 revolutions per minute, and the stirring time is 5 to 15 minutes. In the third stirring stage, the orbital speed is 20 to 30 revolutions per minute, the rotational speed is 1000 to 1300 revolutions per minute, and the stirring time is 50 to 80 minutes. The rotational speed of the first stirring is 0, the revolutionary speed of the first stirring is 20 revolutions / min to 30 revolutions / min, and the stirring time of the first stirring is 5 minutes to 20 minutes. The stirring time for the second stirring is 50 to 80 minutes, the orbital speed of the second stirring is 25 revolutions / min to 40 revolutions / min, and the rotational speed of the second stirring is 1000 revolutions / min to 1300 revolutions / min. The stirring time for the fourth stirring is 60 to 90 minutes, the orbital speed of the fourth stirring is 25 revolutions / min to 40 revolutions / min, and the rotational speed of the fourth stirring is 1000 revolutions / min to 1300 revolutions / min. A method for producing a positive electrode paste, characterized by the above.

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

3. A method for producing a positive electrode paste according to claim 1, characterized in that the solid content of the positive electrode paste is 65% to 70%, and the viscosity of the positive electrode paste is 6,000 to 31,000 mPa·s.

4. A method for producing a positive electrode paste according to claim 1, characterized in that, 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%.

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

6. The method for producing a positive electrode paste according to claim 1, characterized in that the positive electrode active material is at least one of lithium iron phosphate and its modifying material, and lithium nickel cobalt manganese oxide and its modifying material, and the modifying material is produced by one or more modification methods of doping, conductive carbon coating, conductive metal coating, and conductive polymer coating.

7. The method for producing a positive electrode paste according to claim 1, characterized in that 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.

8. The method for producing a positive electrode paste according to Claim 1, characterized in that the solid content of the positive electrode paste is 65% to 70%, the initial viscosity is 6,000 to 31,000 mPa·s, and after standing for 24 hours, the viscosity does not exceed 49,000 mPa·s.

9. A method for manufacturing a secondary battery, wherein the secondary battery comprises a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte, and the positive electrode sheet is manufactured from a positive electrode paste manufactured by the method for manufacturing a positive electrode paste described in claim 1.

10. The method for manufacturing a secondary battery according to claim 9, characterized in that the secondary battery is one of a lithium-ion battery, a sodium-ion battery, a magnesium-ion battery, or a potassium-ion battery.

11. A method for manufacturing a battery module, wherein the battery module includes a secondary battery manufactured by the method for manufacturing a secondary battery described in Claim 9.

12. A method for manufacturing a battery pack, wherein the battery pack includes a secondary battery manufactured by the method for manufacturing a secondary battery described in Claim 9.

13. A method for manufacturing a power consumption device, characterized in that the power consumption device includes a secondary battery manufactured by the method for manufacturing a secondary battery described in Claim 9.

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