Secondary battery, method for manufacturing the same, and power consumption device

Abstract

The present application provides a secondary battery including a positive electrode plate. The positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector. The positive electrode film layer contains a conductive agent, and the conductive agent includes a first conductive carbon black and a second conductive carbon black. The specific surface area of the second conductive carbon black is larger than the specific surface area of the first conductive carbon black. In addition, the present application further provides a method for manufacturing the secondary battery and a power consumption device. The secondary battery of the present application realizes a low internal resistance and improves the energy density and cycle performance of the battery.

Description

Technical Field

[0001] This application relates to the technical field of secondary batteries, and particularly to secondary batteries, their manufacturing methods, and power consumption devices.

Background Art

[0002] In recent years, secondary batteries have been very widely applied in many fields such as energy storage systems such as wind power, thermal power, hydropower, and solar power plants, and electric tools, electric bicycles, etc.

[0003] A secondary battery generally includes positive and negative electrode plates, an electrolyte, and a separator disposed between the positive and negative electrode plates. When manufacturing the electrode plate, in order to make the electrode plate satisfy a certain conductivity, generally a conductive agent is added to the electrode plate. However, due to the addition of the conductive agent, the occupancy rate of the active material in the electrode plate decreases, thereby causing a decrease in the energy density.

[0004] Therefore, how to develop a secondary battery that can achieve a low internal resistance and at the same time achieve a high energy density and electrical performance is one of the urgent problems that researchers need to solve.

Summary of the Invention

Problems to be Solved by the Invention

[0005] This application is made in view of the above problems, and its purpose is to provide a secondary battery for achieving a low internal resistance and improving the energy density and cycle performance of the battery.

Means for Solving the Problems

[0006] To achieve the above object, a first aspect of the present application provides a secondary battery. This secondary battery includes a positive electrode plate, and the positive electrode plate includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector. The positive electrode film layer contains a conductive agent, and the conductive agent includes a first conductive carbon black and a second conductive carbon black. The specific surface area of the second conductive carbon black is larger than the specific surface area of the first conductive carbon black.

[0007] By using two types of conductive carbon blacks with different specific surface areas, the internal resistance and cycle performance of the battery can be improved without increasing the amount of the conductive agent used.

[0008] In any embodiment, when the specific surface area of the first conductive carbon black is denoted as S1 and the specific surface area of the second conductive carbon black is denoted as S2, S2 / S1 ≧ 4, and optionally, 5 ≦ S2 / S1 ≦ 17.

[0009] By setting the ratio of the specific surface areas of the first conductive carbon black and the second conductive carbon black within the above range, the improvement of the internal resistance and cycle performance of the battery can be better realized.

[0010] In any embodiment, the specific surface area of the first conductive carbon black ≦ 140 m 2 [[ID=第十八]] / g, and optionally 50 m 2 / g ~ 130 m 2 / g, and / or the specific surface area of the second conductive carbon black is 200 m 2 / g ~ 1200 m 2 / g, and optionally 300 m 2 / g ~ 1000 m 2 / g.

[0011] In any embodiment, the conductive agent (1) The mass occupancy rate of the conductive agent in the positive electrode film layer ≦ 5%, and optionally 0.8% ~ 3.0%, (2) The mass occupancy of the first conductive carbon black in the positive electrode film layer is ≤ 4.2%, and optionally 0.4% to 3%. (3) The mass occupancy of the second conductive carbon black in the positive electrode film layer is ≤2.5%, and optionally 0.1% to 2%, and (4) The mass ratio of the first conductive carbon black to the second conductive carbon black is (0.4 to 8):1, and optionally (0.5 to 7):1, satisfying at least one of these conditions.

[0012] In any embodiment, the oil absorption capacity of the first conductive carbon black is ≤ 260, and / or the oil absorption capacity of the second conductive carbon black is ≤ 300.

[0013] In any embodiment, the water content of the first conductive carbon black is ≤ 5000 ppm, and / or the water content of the second conductive carbon black is ≤ 10000 ppm.

[0014] In any embodiment, the conductive agent further comprises carbon nanotubes. The diameter of the carbon nanotube is optionally 4 to 10 nm. The length of the carbon nanotube is optionally 0.3 to 50 μm. The aspect ratio of the carbon nanotube is optionally between 50 and 12500. Optionally, the carbon nanotubes include multi-walled carbon nanotubes. Optionally, the mass occupancy rate of carbon nanotubes in the positive electrode film layer is ≤1.2%. Optionally, the mass ratio of the second conductive carbon black to the carbon nanotube is (0.1 to 10):1.

[0015] In any embodiment, the first conductive carbon black and the second conductive carbon black are each independently selected from at least one of furnace carbon black, acetylene black, Super p, and Ketjen black.

[0016] A second aspect of this application further provides a method for manufacturing a secondary battery as described in the first aspect of this application. This method includes manufacturing a positive electrode plate by employing the following steps. S1, a step of dry mixing a first conductive carbon, a second conductive carbon, and a first dispersant in a stirring tank to obtain a powder mixture. Here, the specific surface area of ​​the second conductive carbon black is larger than the specific surface area of ​​the first conductive carbon black. S2, a step in which a solvent is added to the powder mixture and mixed uniformly to obtain slurry 1. Step S3: Add the second dispersant to slurry 1, mix uniformly, and obtain slurry 2. S4. Add the positive electrode active material to the slurry 2 and mix uniformly to obtain a positive electrode material slurry. S5, a step of coating the positive electrode material slurry onto at least one surface of the positive electrode current collector, drying it, and then forming a positive electrode film layer.

[0017] In any embodiment, the first dispersant comprises a vinylidene fluoride polymer. Optionally, the first dispersant comprises a vinylidene fluoride homopolymer, or a compound of the first dispersant obtained by copolymerizing vinylidene fluoride with an active group-containing vinylidene fluoride. Here, the active group comprises at least one of a carboxyl group, an epoxy group, a hydroxyl group, or a sulfonic acid group, and is optionally a carboxyl group or an epoxy group.

[0018] In any embodiment, the second dispersant is selected from a copolymer of ethylene and maleic anhydride, or a copolymer of styrene and maleic anhydride.

[0019] In any embodiment, the mass ratio of the sum of the masses of the first conductive carbon black and the second conductive carbon black to the mass ratio of the first dispersant is (0.4 to 2.0):1, and optionally (0.75 to 1.8):1.

[0020] In any embodiment, the mass ratio of the sum of the masses of the first conductive carbon black and the second conductive carbon black to the mass ratio of the second dispersant is (8-30):1, and optionally (9-25):1.

[0021] In any embodiment, in step S3, the second dispersant and carbon nanotubes (CNTs) are added to slurry 1 and uniformly mixed to obtain slurry 2.

[0022] In any embodiment, the content a of the first conductive carbon black, the content b of the second conductive carbon black, and the content c of the carbon nanotubes satisfy 0.2 ≤ ((a+b)×c) / (a×b) ≤ 10, and optionally 0.4 ≤ ((a+b)×c) / (a×b) ≤ 6. Here, a, b, and c are based on the total weight of the conductive slurry, with respect to its dry weight.

[0023] A third aspect of this application provides a power consumption device comprising at least one of a secondary battery according to the first aspect of this application and a secondary battery manufactured by the method of the second aspect of this application.

[0024] The power consumption device of this application includes a secondary battery according to this application, and therefore has at least the same advantages as the aforementioned secondary battery. [Brief explanation of the drawing]

[0025] [Figure 1] This is a schematic diagram of a battery cell according to one embodiment of the present application. [Figure 2] Figure 1 is an exploded view of a battery cell 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 in which a secondary battery is used as a power source according to one embodiment of this application. [Modes for carrying out the invention]

[0026] The following describes in detail embodiments specifically disclosing the secondary battery, its manufacturing method, and power consumption device of this application, with appropriate reference to the drawings. 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 do not limit the topics described in the claims.

[0027] 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" means that all real numbers between "0 to 5" are listed herein, and "0 to 5" is simply an abbreviated representation of combinations of these numbers. Also, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that the parameter is an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0028] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical inventions.

[0029] Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical concepts.

[0030] 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 mentioned 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), etc.

[0031] Unless otherwise specified, the terms "include" and "include" as used in this application refer to an open type, but may also refer to a closed type. For example, the terms "include" and "include" may mean that other components not listed may be included or included, or that only the listed components may be included or included.

[0032] 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."

[0033] The inventors found the following in their research: The conductive slurries used in the prior art have low conductivity, requiring the use of a large amount of conductive slurry to meet the demand for the conductivity of the electrode plates. However, this reduces the occupancy rate of the active material in the positive electrode film layer, which is detrimental to improving energy density. For this reason, those skilled in the art generally add graphene, which has higher conductivity, to the conductive slurry. However, graphene is expensive and does not offer a cost advantage.

[0034] The inventors, through diligent research, have discovered the following: By manufacturing a cathode active slurry using a first conductive carbon black and a second conductive carbon black with different specific surface areas, the internal resistance of a secondary battery can be effectively improved, the amount of conductive agent used can be reduced, and the occupancy rate of the active material can be increased, thereby improving energy density. Furthermore, compared to graphene, carbon black has a lower price, offering a cost advantage, and also has higher dispersibility. By further optimizing the blending ratio of each substance in the system, the internal resistance of the secondary battery can be further improved, thereby contributing to an increase in the energy density of the secondary battery and an improvement in cycle performance.

[0035] Therefore, a first aspect of this application provides a secondary battery, the secondary battery including a positive electrode plate. The positive electrode plate 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 includes a conductive agent, the conductive agent including a first conductive carbon black and a second conductive carbon black. The specific surface area of ​​the second conductive carbon black is greater than the specific surface area of ​​the first conductive carbon black.

[0036] By using two types of conductive carbon black with different specific surface areas, it is possible to improve the internal resistance and cycle performance of the battery without increasing the amount of conductive agent used.

[0037] In some embodiments, if the specific surface area of ​​the first conductive carbon black is S1 and the specific surface area of ​​the second conductive carbon black is S2, then S2 / S1 ≥ 4, and optionally, 5 ≤ S2 / S1 ≤ 17.

[0038] By setting the ratio of the specific surface areas of the first conductive carbon black and the second conductive carbon black within the above range, improvements in the battery's internal resistance and cycle performance can be better achieved.

[0039] In some embodiments, the specific surface area of the first conductive carbon black ≤ 140 m 2 / g, optionally 50 m 2 / g to 130 m 2 / g, and further optionally 55 m 2 / g to 80 m 2 / g. And / or, the specific surface area of the second conductive carbon black is 200 m 2 / g to 1200 m 2 / g, optionally 300 m 2 / g to 1000 m 2 / g, also optionally 400 m 2 / g to 900 m 2 / g, and further optionally 500 m 2 / g to 800 m 2 / g.

[0040] In some embodiments, the conductive agent (1) The mass occupancy rate of the conductive agent in the positive electrode film layer ≤ 5%, optionally 0.8% to 3.0%, and further optionally 0.9% to 2.5%; (2) The mass occupancy rate of the first conductive carbon black in the positive electrode film layer ≤ 4.2%, optionally 0.4% to 3%, and further optionally 0.5% to 2.5%; (3) The mass occupancy rate of the second conductive carbon black in the positive electrode film layer ≤ 2.5%, optionally 0.1% to 2%, and further optionally 0.4% to 1%; and (4) The mass ratio of the first conductive carbon black to the second conductive carbon black is (0.4 to 8):1, optionally (0.5 to 7):1, satisfying at least one of the above.

[0041] In some embodiments, the oil absorption amount of the first conductive carbon black ≤ 260, and / or the oil absorption amount of the second conductive carbon black ≤ 300.

[0042] Oil absorption is a term known in the art and can be measured using instruments and methods known in the art. For example, it may be measured using oil absorption test equipment (e.g., HiTEC Keithley SourceMeter) by referring to the ASTM D2414 oil absorption test standard.

[0043] In some embodiments, the water content of the first conductive carbon black is ≤ 5000 ppm, and / or the water content of the second conductive carbon black is ≤ 10000 ppm.

[0044] The water content can be measured using instruments and methods known in this field. For example, it may be measured using a Coulomb water titrator (e.g., the 774 Test method), referring to the Karl Fischer method GB / T 11133-2015.

[0045] In some embodiments, the conductive agent further comprises carbon nanotubes. The diameter of the carbon nanotube is optionally 4-10 nm, and optionally 5-8 nm. The length of the carbon nanotube is optionally 0.3 to 50 μm, and optionally 0.8 to 40 μm. The aspect ratio of the carbon nanotube is optionally 50 to 12500, and optionally 100 to 8000. Optionally, the carbon nanotubes include multi-walled carbon nanotubes. Optionally, the mass occupancy of carbon nanotubes in the positive electrode film layer is ≤1.2%, and optionally, ≤0.6%. Optionally, the mass ratio of the second conductive carbon black to the carbon nanotube is (0.1-10):1, optionally (0.2-6):1, and optionally (0.3-4):1.

[0046] In this application, the diameter of the carbon nanotubes is measured by GB / T 26826-2011, and the length of the carbon nanotubes is measured by scanning electron microscopy statistical method.

[0047] In some embodiments, the first conductive carbon black and the second conductive carbon black are each independently selected from at least one of furnace carbon black, acetylene black, Super p, and Ketjen black. Optionally, the first conductive carbon black and the second conductive carbon black may be the same type of carbon black or different types of carbon black, but are optionally the same type of carbon black.

[0048] In some embodiments, the positive electrode film layer further comprises a dispersant, the dispersant comprising a first dispersant and a second dispersant.

[0049] In some embodiments, the first dispersant comprises a vinylidene fluoride polymer. Optionally, the first dispersant includes a vinylidene fluoride homopolymer, or a compound of the first dispersant obtained by copolymerizing vinylidene fluoride with an active group-containing vinylidene fluoride. Here, the active group includes at least one of a carboxyl group, an epoxy group, a hydroxyl group, or a sulfonic acid group, and is optionally a carboxyl group or an epoxy group.

[0050] In some embodiments, the number-average molecular weight of the first dispersant is 100,000 to 5,000,000, and optionally 500,000 to 3,000,000.

[0051] In some embodiments, the second dispersant is selected from copolymers of ethylene and maleic anhydride, and copolymers of styrene and maleic anhydride. Optionally, its number-average molecular weight is 10,000 to 200,000, and optionally 50,000 to 150,000.

[0052] In this application, the number-average molecular weight is measured using gel permeation chromatography (GPC) according to GB / T 21863-2008 "Gel permeation chromatography (GPC) with tetrahydrofuran as the eluent" (equivalent to adopting the German standard DIN 55672-1:2007 "Gel permeation chromatography (GPC) Part 1: Using tetrahydrofuran (THF) as the eluent").

[0053] In this application, the positive electrode plate includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector. For example, the positive electrode current collector has two opposing surfaces in its 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.

[0054] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, aluminum foil may be used as the metal foil sheet. The composite current collector may include a polymer material substrate 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 aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer material substrate (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0055] In this application, the positive electrode material is Li + It is a compound that can reversibly absorb and release substances.

[0056] In some embodiments, the positive electrode active material may be a positive electrode active material for batteries that is well known in the art. For example, the positive electrode active material may include at least one material from among lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and modified compounds thereof. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may be used. These positive electrode active materials may be used individually or in combination of two or more. Here, 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(NCM 333 (This can be abbreviated as LiNi) 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (This can be abbreviated as LiNi) 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (This can be abbreviated as LiNi) 0.6 Co 0.2 Mn 0.2 O2(NCM 622 (This can be abbreviated as LiNi) 0.8 Co 0.1 Mn 0.1 O2(NCM 811 (This may be abbreviated as LiNi) Lithium nickel cobalt aluminum oxide (for example, LiNi 0.85 Co 0.15 Al 0.05It may include, 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 (which may be abbreviated as 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.

[0057] In some embodiments, the positive electrode active material is optionally a lithium-containing composite oxide having a layered or spinel-like structure, such as LiCoO2, LiMn2O4, LiNiO2, LiNi 1 / 2 Mn 1 / 2 Lithium manganese nickel composite oxides such as O2, LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2, LiLiLi 0.6 Mn 0.2 Co 0.2 Lithium manganese nickel cobalt composite oxides such as O2, or LiNi 1-x-y-z Co x Al y Mg z This refers to lithium-containing composite oxides such as O2 (where 0≦x≦1, 0≦y≦0.1, 0≦z≦0.1, and 0≦1-xyz≦1). Furthermore, lithium-containing composite oxides in which some of the constituent elements of the above lithium-containing composite oxide are substituted with additive elements such as Ge, Ti, Zr, Mg, Al, Mo, and Sn are also included within the scope of this application.

[0058] In addition to the positive electrode active materials described above, other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used individually or in combination of two or more. For example, by using a combination of a layered lithium-containing composite oxide and a spinel-structured lithium-containing composite oxide, it is possible to achieve both increased capacity and improved safety.

[0059] In some embodiments, the positive electrode active material includes lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium manganate, lithium cobaltate, lithium nickel cobaltate, lithium nickel manganate, lithium iron phosphate, lithium titanate, and derivatives or combinations thereof in which their elemental positions are substituted or doped with transition metals or non-transition metals.

[0060] In some embodiments, the mass occupancy of the positive electrode active material in the positive electrode film layer is 90% to 97.1%, and optionally 95% to 97.1%.

[0061] In some embodiments, the positive electrode film layer optionally further comprises an adhesive. The adhesive is one of the adhesives commonly used in the battery field, such as polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene ternary copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene ternary copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and polyethylene oxide.

[0062] In some embodiments, the dry weight of the adhesive accounts for 0.1% to 3.5% of the total weight of the positive electrode film layer based on dry weight, and optionally accounts for 0.5% to 2.5%.

[0063] A second aspect of this application further provides a method for manufacturing a secondary battery as described in the first aspect of this application. This method includes manufacturing a positive electrode plate by employing the following steps. S1, a step of dry mixing a first conductive carbon, a second conductive carbon, and a first dispersant in a stirring tank to obtain a powder mixture. Here, the specific surface area of ​​the second conductive carbon black is larger than the specific surface area of ​​the first conductive carbon black. S2, a step in which a solvent is added to the powder mixture and mixed uniformly to obtain slurry 1. Step S3: Add the second dispersant to slurry 1, mix uniformly, and obtain slurry 2. S4. Add the positive electrode active material to the slurry 2 and mix uniformly to obtain a positive electrode material slurry. S5, a step of coating the positive electrode material slurry onto at least one surface of the positive electrode current collector, drying it, and then forming a positive electrode film layer.

[0064] In some embodiments, the first dispersant comprises a vinylidene fluoride polymer. Optionally, the first dispersant includes a vinylidene fluoride homopolymer, or a compound of the first dispersant obtained by copolymerizing vinylidene fluoride with an active group-containing vinylidene fluoride. Here, the active group includes at least one of a carboxyl group, an epoxy group, a hydroxyl group, or a sulfonic acid group, and is optionally a carboxyl group or an epoxy group.

[0065] In some embodiments, the second dispersant is selected from a copolymer of ethylene and maleic anhydride, or a copolymer of styrene and maleic anhydride.

[0066] In some embodiments, the mass ratio of the sum of the masses of the first conductive carbon black and the second conductive carbon black to the mass ratio of the first dispersant is (0.4 to 2.0):1, and optionally (0.75 to 1.8):1.

[0067] In some embodiments, the mass ratio of the sum of the masses of the first conductive carbon black and the second conductive carbon black to the mass ratio of the second dispersant is (8-30):1, and optionally (9-25):1.

[0068] In some embodiments, each mixing in steps S1 to S4 may be carried out by employing the following operations: the stirring linear velocity is 5 m / s to 25 m / s, optionally 8 m / s to 20 m / s, and the stirring time is 10 minutes to 60 minutes, optionally 13 minutes to 40 minutes.

[0069] In some embodiments, the solvent is selected from at least one of N-methylpyrrolidone (NMP), N,N-dimethylacetamide, and dimethyl sulfoxide.

[0070] In some embodiments, in step S3, the second dispersant and carbon nanotubes (CNTs) are added to slurry 1 and uniformly mixed to obtain slurry 2.

[0071] In some embodiments, the content a of the first conductive carbon black, the content b of the second conductive carbon black, and the content c of the carbon nanotubes satisfy 0.2 ≤ ((a+b)×c) / (a×b) ≤ 10, and optionally 0.4 ≤ ((a+b)×c) / (a×b) ≤ 6. Here, a, b, and c are based on the total weight of the conductive slurry, with respect to its dry weight.

[0072] The secondary battery of this application will be described below with reference to the drawings as appropriate. The secondary battery may include a battery cell, a battery module, or a battery pack.

[0073] One embodiment of this application provides a battery cell.

[0074] Generally, a battery cell includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During charging and discharging of the battery, active ions are absorbed and released as they move back and forth between the positive and negative electrode plates. The electrolyte acts as a conductor of ions between the positive and negative electrode plates. The separator is placed between the positive and negative electrode plates and primarily serves to prevent short circuits between the positive and negative electrodes, while also allowing ions to pass through.

[0075] [Secondary battery] A second aspect of this application provides a secondary battery, which includes the separator described in the first aspect of this application. Generally, in addition to the separator, the secondary battery further includes a positive electrode plate, a negative electrode plate, and an electrolyte.

[0076] In particular, this application may be used in lithium metal batteries as a replacement for conventional separators. The negative electrode may be lithium metal or a lithium alloy, or there may be no negative electrode at all. The applicable positive electrode materials are as described above. In the case of a lithium metal battery without a negative electrode, the positive electrode material needs to provide a lithium source.

[0077] The secondary battery may be manufactured using methods commonly used in this field. For example, an electrode assembly may be manufactured by a winding or lamination process using a positive electrode plate, a negative electrode plate, and a separator, and then an electrolyte may be injected into the electrode assembly and sealed to produce the secondary battery.

[0078] It should be noted that the secondary battery described in this application includes a button-type battery. When the secondary battery is a button-type battery, the materials of the positive electrode plate and the negative electrode plate may be the same or different. Furthermore, the button-type battery may be manufactured by a method commonly used by those skilled in the art. For example, the positive electrode plate, separator and negative electrode plate may be assembled as an electrode assembly, and then the electrolyte may be injected into the electrode assembly and sealed to manufacture the button-type battery.

[0079] The following sections will explain each of the above-mentioned components of the secondary battery.

[0080] [negative electrode plate] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer placed on at least one surface of the negative electrode current collector. For example, the negative electrode current collector has two opposing surfaces in its thickness direction, and the negative electrode film layer is placed on one or both of the two opposing surfaces of the negative electrode current collector.

[0081] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, copper foil may be used as the metal foil sheet. The composite current collector may include a polymer material substrate 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)).

[0082] In this application, the negative electrode material is lithium metal or a lithium-capable intercalation-deintercalation compound.

[0083] In some embodiments, the negative electrode active material may be a negative electrode active material for batteries that is well known in the art. For example, various materials such as alloys or oxides of aluminum, silicon, tin, and carbon materials may be used as negative electrode active materials. Optionally, examples of oxides include titanium dioxide, and examples of carbon materials include graphite, pyrolysis carbon systems, coke systems, glassy carbon systems, calcined organic polymer compounds, and mesocarbon microbeads. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, this application is not limited to these materials, and other conventional materials usable as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used individually or in combination of two or more.

[0084] In some embodiments, optionally, the dry weight of the negative electrode active material accounts for 75% to 99% of the total weight of the negative electrode film layer based on dry weight, and optionally, 80% to 97%.

[0085] In some embodiments, the negative electrode film layer optionally further comprises an adhesive. The adhesive is one of the adhesives commonly used in the battery field, such as polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene ternary copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene ternary copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and polyethylene oxide.

[0086] In some embodiments, the dry weight of the adhesive optionally accounts for 0.1 to 3.5% and optionally 0.5 to 2.5% of the total weight of the negative electrode film layer based on dry weight.

[0087] In some embodiments, the negative electrode film layer optionally further comprises 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.

[0088] In some embodiments, the dry weight of the conductive agent optionally accounts for 0.05 to 5% of the total weight of the negative electrode film layer based on dry weight, and optionally accounts for 0.5 to 3%.

[0089] In some embodiments, the negative electrode film layer optionally further comprises other auxiliary agents, such as thickeners (e.g., sodium carboxymethylcellulose (CMC-Na)).

[0090] In some embodiments, the negative electrode plate may be manufactured by the following method: The above components for manufacturing the negative electrode plate, such as a negative electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry; the negative electrode slurry is applied to a negative electrode current collector; and the negative electrode plate is obtained through processes such as drying and cold pressing.

[0091] [Electrolyte] The electrolyte plays a role in conducting ions between the positive and negative electrodes. 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.

[0092] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0093] In some embodiments, a non-aqueous solvent (organic solvent) is used as the non-aqueous electrolyte. Non-aqueous solvents include carbonate-based and ether-based solvents.

[0094] In some embodiments, the carbonate system includes cyclic carbonates and linear carbonates. Examples of cyclic carbonates include ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, and sulfur-based esters (ethylene glycol sulfide). Examples of linear carbonates include low-viscosity polar linear carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, and aliphatic branched carbonate compounds. A mixed solvent of cyclic carbonates (especially ethylene carbonate) and linear carbonates is particularly preferred.

[0095] Examples of ether-based compounds include dimethyl ether tetraethylene glycol (TEGDME), ethylene glycol dimethyl ether (DME), and 1,3-dioxolane (DOL).

[0096] In addition to the non-aqueous solvents mentioned above, other non-aqueous solvents (organic solvents) such as linear alkyl esters like methyl propionate, linear triesters like trimethyl phosphate, nitrile solvents like 3-methoxypropionitrile, and branched compounds having ether bonds, such as dendrimer compounds, may also be used.

[0097] Alternatively, a fluorine-based solvent may be used.

[0098] As fluorine-based solvents, for example, H(CF2)2OCH3, C4F9OCH3, H(CF2)2OCH2CH3, H(CF2)2OCH2CF3, H(CF2)2CH2O(CF2)2H, etc., or linear (perfluoroalkyl) alkyl ethers such as CF3CHFCF2OCH3, CF3CHFCF2OCH2CH3, etc., for example, 2-trifluoromethylhexafluoropropyl methyl ether, 2-trifluoromethylhexafluoropropyl ethyl ether, 2-trifluoromethylhexafluoropropyl propyl ether, 3-trifluoromethyl octafluorobutyl methyl ether, 3-trifluoromethyl octafluorobutyl ethyl ether, 3-trifluoromethyl octafluorobutyl propyl ether, 4-trifluoromethyldecafluoropentyl methyl ether Examples include ether, 4-trifluoromethyl decafluoropentyl ethyl ether, 4-trifluoromethyl decafluoropentyl propyl ether, 5-trifluoromethyl dodecafluorohexyl methyl ether, 5-trifluoromethyl dodecafluorohexyl ethyl ether, 5-trifluoromethyl dodecafluorohexyl propyl ether, 6-trifluoromethyl tetradecafluoroheptyl methyl ether, 6-trifluoromethyl tetradecafluoroheptyl ethyl ether, 6-trifluoromethyl tetradecafluoroheptyl propyl ether, 7-trifluoromethyl hexadecafluorooctyl methyl ether, 7-trifluoromethyl hexadecafluorooctyl ethyl ether, and 7-trifluoromethyl hexadecafluorooctyl propyl ether.

[0099] Furthermore, the above-mentioned iso(perfluoroalkyl)alkyl ether may be used in combination with the above-mentioned linear (perfluoroalkyl)alkyl ether.

[0100] Lithium salts such as lithium perchlorates, organoboro lithium salts, fluorine-containing lithium salts, and lithium imide salts are preferred as electrolyte salts used in non-aqueous electrolytes.

[0101] Examples of such electrolyte salts include, for example, LiClO4, LiPF6, LiBF4, LiAsF6, LiSbF6, LiCF3SO3, LiCF3CO2, LiC2F4(SO3)2, LiN(C2F5SO2)2, LiC(CF3SO2)3, LiC n F 2n+1 SO3(n≧2), LiN(R f In equation OSO2)2, R f Examples include fluoroalkyl groups. Among these lithium salts, fluorine-containing organic lithium salts are particularly preferred. Fluorine-containing organic lithium salts are highly anionic and easily separated into ions, making them readily soluble in non-aqueous electrolytes.

[0102] The concentration of the lithium electrolyte in the non-aqueous electrolyte is, for example, 0.3 mol / L (moles / liter) or higher, and optionally 0.7 mol / L or higher, optionally 1.7 mol / L or lower, and optionally 1.2 mol / L or lower. If the concentration of the lithium electrolyte is too low, the ionic conductivity will be too low. If the concentration of the lithium electrolyte is too high, there is a concern that undissolved electrolyte salts will precipitate.

[0103] In some embodiments, the electrolyte optionally further includes additives, but this application is not particularly limited. For example, the additives may include a negative electrode film forming additive and a positive electrode film forming additive, and may further include additives that can improve some of the battery's performance, such as additives that improve the battery's overcharge performance, or additives that improve the battery's high-temperature or low-temperature performance.

[0104] [Separator] In some embodiments, the battery cell 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.

[0105] 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. If the separator is a multilayer composite film, the materials of each layer may be the same or different, and is not particularly limited.

[0106] In some embodiments, the battery cell may include an outer casing. This casing may be used to package the electrode assembly and electrolyte.

[0107] In some embodiments, the battery cell casing may be a rigid case, such as a rigid plastic case, an aluminum case, or a steel case. The battery cell casing may also be a pouch, such as a bag-shaped pouch. The pouch material may be plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0108] This application does not particularly limit the shape of the battery cell, which may be cylindrical, rectangular, or any other shape. For example, Figure 1 shows a rectangular battery cell 5 as an example.

[0109] 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, and the bottom plate and side plates surround and form a housing cavity. The case 51 has an opening that communicates with the housing cavity, and the cover plate 53 can close the housing cavity by covering the opening. The positive electrode plate, negative electrode plate 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 permeates the electrode assembly 52. ​​The number of electrode assemblies 52 included in the battery cell 5 may be one or more, and those skilled in the art can specifically select according to actual needs.

[0110] In some embodiments, the battery cells may be assembled into a battery module. The number of battery cells 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.

[0111] Figure 3 shows an example of a battery module 4. Referring to Figure 3, in the battery module 4, the multiple battery cells 5 may be arranged sequentially along the longitudinal direction of the battery module 4. Of course, they may be arranged according to any other method. Furthermore, the multiple battery cells 5 may be fixed with fasteners.

[0112] Optionally, the battery module 4 may further include a housing having a housing space, and a plurality of battery cells 5 are housed in the housing space.

[0113] In some embodiments, the battery cells may be assembled into a battery pack. 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, the specific number of which can be selected by those skilled in the art based on the application and capacity of the battery pack.

[0114] 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 provided to cover the lower housing 3 and forming a sealed space for housing the battery modules 4. The plurality of battery modules 4 may be arranged inside the battery box in any manner.

[0115] Furthermore, this application provides a power consumption device, the power consumption device including a secondary battery according to this application. The secondary battery 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, laptop computers, 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.

[0116] As the aforementioned power consumption device, a secondary battery can be selected according to the usage requirements.

[0117] 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 power consumption device's demand for high power and high energy density of secondary batteries, a battery pack or battery module can be employed.

[0118] Other examples of devices may include mobile phones, tablet computers, and laptop computers. These devices generally require thinness and lightness, and can utilize battery cells as a power source.

[0119] Examples The following describes examples of this application. The examples described below are illustrative and are for interpretive purposes only, and should not be considered as limitations thereon. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in the art or in the product instructions shall be followed. Unless the manufacturer is specified for the reagents or instruments used, they are all common commercially available products. Unless otherwise specified, the masses of the substances used in the examples are the masses excluding crystal water.

[0120] Example 1 Manufacturing of rechargeable batteries 1. Manufacturing of the positive electrode plate The first conductive carbon black (Super P), the second conductive carbon black (Ketjenblack), and the first dispersant (PVDF 5130) were dry-mixed in a mass ratio of 3:1:3 and dispersed in a stirring tank at a linear velocity of 10 m / s for 15 minutes. Here, the specific surface area SSA (i.e., S1) of the first conductive carbon black was 60 m². 2 The ratio is / g, and the specific surface area SSA (i.e., S2) of the second conductive carbon black is 600m². 2 The value was / g, and S2 / S1 = 10.

[0121] The obtained product was added to NMP solvent and dispersed at a linear velocity of 15 m / s for 30 min to obtain slurry 1. The solid content was 10.5%.

[0122] A second dispersant (a copolymer of ethylene and maleic anhydride, Mn=100000) was added to slurry 1, and then dispersed at a linear velocity of 15 m / s for 15 minutes to obtain slurry 2. The first conductive carbon black + second conductive carbon black and the second dispersant were mixed in a mass ratio of 10:1, and the positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811) was added to the above mixture and mixed continuously to obtain a positive electrode active slurry. The mass ratio of the added positive electrode active material, based on the weight of the positive electrode film layer after drying, was 96.3%.

[0123] A positive electrode activated slurry was applied to the aluminum foil of the positive electrode current collector, and a positive electrode plate was obtained through processes such as drying, cold pressing, slitting, and cutting. The surface density of the positive electrode plate was 300 mg / mm². 2 The compacted density is 3.3 g / cm³. 3 That was the case.

[0124] 2. Manufacturing of the negative electrode plate A negative electrode slurry was obtained by uniformly mixing artificial graphite, a negative electrode active material, carbon black (Super P), a conductive agent, styrene-butadiene rubber (SBR), an adhesive, and sodium carboxymethylcellulose (CMC) in a suitable amount of deionized water, a solvent, in a mass ratio of 96:1:1.5:1.5. The negative electrode slurry was applied to the copper foil of the negative electrode current collector, and a negative electrode plate was obtained through drying, cold pressing, slitting, and cutting processes. The surface density of the negative electrode plate was 185 mg / mm². 2 The compacted density is 1.6 g / cm³. 3 That was the case.

[0125] 3. Manufacturing of electrolyte Ethylene carbonate (EC) and methyl ethyl carbonate (EMC) were mixed in a mass ratio of 30:70 to obtain an organic solvent. Sufficiently dried LiPF6 was dissolved in the above organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0126] 4. Separator A porous polymerized polyethylene (PE) film with a thickness of 13 μm was used as the separator.

[0127] 5. Manufacturing of rechargeable batteries An electrode assembly was obtained by sequentially stacking and winding a positive electrode plate, a separator, and a negative electrode plate. The electrode assembly was placed in an outer casing, dried, and then injected with electrolyte. A secondary battery was obtained through processes such as vacuum packaging, settling, chemical formation, and shaping. The margin of safety was 89%.

[0128] Examples 2-16 The method for manufacturing the secondary battery was the same as in Example 1, but only the conductive agent in the positive electrode slurry was changed, and carbon nanotubes (CNTs) were optionally added. For details, please refer to Table 1.

[0129] Comparative Example 1 The method for manufacturing the secondary battery was the same as in Example 1, but when manufacturing the positive electrode slurry, only the first conductive carbon black was used.

[0130] Comparative Example 2 The method for manufacturing the secondary battery was the same as in Example 1, but when manufacturing the positive electrode slurry, only the second conductive carbon black was used.

[0131] Test methods for related parameters 1. Specific surface area test For the specific surface area test, we referred to GB / T 19587-2017 and used the Tri-Star 3020 specific surface area pore size analysis instrument from Micromeritics, Inc., USA, to perform the specific surface area analysis test using nitrogen gas adsorption. The specific surface area of ​​the material was calculated using the BET (Brunauer Emmett Teller) method. Please refer to Table 1 for the test results.

[0132] 2.25℃ DCR ​​test At 25°C, the battery was charged with a constant current of 0.5C until it reached 4.25V, and then with a constant voltage until the current reached 0.05C. The battery was then discharged with a constant current of 0.5C for 30 minutes to adjust it to 50% SOC (State of Charge), and the voltage at this point was defined as U1. The battery was then discharged with a constant current of 4C for 30 seconds, and a sample was taken at 0.1 seconds, and the voltage at the end of discharge was defined as U2. The initial DCR of the battery was expressed using the discharge DCR when the battery was at 50% SOC, and the initial DCR of the battery is given by (U1-U2) / 4C.

[0133] 3.25℃ cycle performance test At 25°C, the secondary batteries manufactured in each example and comparative example were charged at a rate of 1C with a constant current until the cutoff voltage reached 4.25V. Then, they were charged at a constant voltage until the current was ≤0.05C, and left to stand for 5 minutes. Furthermore, they were discharged at a rate of 0.33C with a constant current until the cutoff voltage reached 2.8V, and left to stand for 5 minutes. This constituted one charge-discharge cycle. Following this method, the battery cycle charge-discharge test was performed until the battery capacity decreased to 80%. The number of cycles was recorded and determined as the battery's cycle life at 25°C.

[0134] [Table 1] TIFF0007842903000002.tif241169 TIFF0007842903000003.tif157169

[0135] [Table 2]

[0136] As can be seen from Tables 1 and 2, by using the two types of conductive carbon black described in this application, we were able to achieve excellent conductivity and improved battery cycle performance without increasing the amount of conductive agent used.

[0137] It should be noted that this application is not limited to the embodiments described above. The embodiments described above are illustrative, 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 proposal of this application. Furthermore, other forms constructed by combining some of the components of the embodiments, with various modifications that a person skilled in the art could conceive of, are also included within the scope of this application, as long as they do not depart from the spirit of this application. [Explanation of Symbols]

[0138] 1 Battery pack, 2 Upper housing, 3 Lower housing, 4 Battery module, 5 Battery cell, 5 1 Case, 5 Electrode assembly, 5 3 Top cover assembly.

Claims

1. It is a secondary battery, Including the positive electrode plate, The positive electrode plate 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 contains a conductive agent, Here, the conductive agent includes a first conductive carbon black and a second conductive carbon black. The specific surface area of ​​the second conductive carbon black is greater than the specific surface area of ​​the first conductive carbon black. A secondary battery in which, if the specific surface area of ​​the first conductive carbon black is S1 and the specific surface area of ​​the second conductive carbon black is S2, then 5 ≤ S2 / S1 ≤ 10.

2. The specific surface area of ​​the first conductive carbon black is 50 m². ２ / g ~ 140m ２ / g and / or, The specific surface area of ​​the second conductive carbon black is 200 m². ２ / g to 1200m ２ The secondary battery according to claim 1, wherein the value is / g.

3. The secondary battery according to claim 2, wherein the specific surface area of ​​the second conductive carbon black is 200 m² / g to 600 m² / g.

4. The conductive agent is (1) The mass occupancy rate of the conductive agent in the positive electrode film layer is 0.8% to 5%. (2) The mass occupancy of the first conductive carbon black in the positive electrode film layer is 0.4% to 4.2%. (3) The mass occupancy of the second conductive carbon black in the positive electrode film layer is 0.1% to 2.5%, and (4) The mass ratio of the first conductive carbon black to the second conductive carbon black is (0.4 to 8):

1. A secondary battery according to claim 1, satisfying at least one of the following conditions.

5. The secondary battery according to claim 1, wherein the oil absorption amount of the first conductive carbon black is ≤ 260 and / or the oil absorption amount of the second conductive carbon black is ≤ 300.

6. The secondary battery according to claim 1, wherein the water content of the first conductive carbon black is ≤ 5000 ppm, and / or the water content of the second conductive carbon black is ≤ 10000 ppm.

7. The conductive agent further contains carbon nanotubes, The carbon nanotube mentioned above is The diameter of the carbon nanotube is 4 to 10 nm. The tube length of the carbon nanotube is 0.3 to 50 μm. The aspect ratio of the carbon nanotube is 50 to 12500. The carbon nanotubes include multi-walled carbon nanotubes. The mass occupancy rate of the carbon nanotubes in the positive electrode film layer is ≤ 1.2%. The mass ratio of the second conductive carbon black to the carbon nanotube is (0.1 to 10):

1. A secondary battery according to claim 1, satisfying at least one of the following conditions.

8. The secondary battery according to claim 1, wherein the first conductive carbon black and the second conductive carbon black are each independently selected from at least one of furnace carbon black, acetylene black, and Ketjen black.

9. The secondary battery according to claim 1, wherein the positive electrode plate further comprises a vinylidene fluoride polymer.

10. The vinylidene fluoride polymer comprises a vinylidene fluoride homopolymer, or a compound of the first dispersant obtained by copolymerizing vinylidene fluoride with an active group-containing vinylidene fluoride. The secondary battery according to claim 9, wherein the active group comprises at least one of a carboxyl group, an epoxy group, a hydroxyl group, or a sulfonic acid group.

11. The secondary battery according to claim 1, wherein the positive electrode plate further comprises at least one of a copolymer of ethylene and maleic anhydride, or a copolymer of styrene and maleic anhydride.

12. The secondary battery according to claim 9, wherein the positive electrode plate further comprises at least one of a copolymer of ethylene and maleic anhydride, or a copolymer of styrene and maleic anhydride.

13. A method for manufacturing a secondary battery, S1, a step of dry mixing a first conductive carbon black, a second conductive carbon black, and a first dispersant in a stirring tank to obtain a powder mixture, wherein the specific surface area of ​​the second conductive carbon black is greater than the specific surface area of ​​the first conductive carbon black. S2, the step of adding a solvent to the powder mixture and mixing it uniformly to obtain slurry 1. S3, the second dispersant is added to slurry 1 and mixed uniformly to obtain slurry 2. S4, The step of adding the positive electrode active material to the slurry 2 and mixing it uniformly to obtain a positive electrode material slurry. S5, the step of coating the positive electrode material slurry onto at least one surface of the positive electrode current collector, drying it, and then forming a positive electrode film layer, This includes manufacturing a positive electrode plate using the following method: A method for manufacturing a secondary battery, wherein the specific surface area of ​​the first conductive carbon black is S1, and the specific surface area of ​​the second conductive carbon black is S2, such that 5 ≤ S2 / S1 ≤ 10.

14. The production method according to claim 13, wherein the first dispersant comprises a vinylidene fluoride polymer.

15. The first dispersant comprises a vinylidene fluoride homopolymer, or a compound of the first dispersant obtained by copolymerizing vinylidene fluoride with an active group-containing vinylidene fluoride. The manufacturing method according to claim 14, wherein the active group comprises at least one of a carboxyl group, an epoxy group, a hydroxyl group, or a sulfonic acid group.

16. The method for producing the product according to claim 13, wherein the second dispersant is selected from a copolymer of ethylene and maleic anhydride, or a copolymer of styrene and maleic anhydride.

17. The manufacturing method according to any one of claims 13 to 16, wherein the mass ratio of the sum of the masses of the first conductive carbon black and the second conductive carbon black to the mass ratio of the first dispersant is (0.4 to 2.0):

1.

18. The manufacturing method according to claim 17, wherein the mass ratio of the sum of the masses of the first conductive carbon black and the second conductive carbon black to the mass ratio of the second dispersant is (8-30):

1.

19. The manufacturing method according to any one of claims 13 to 16, wherein in step S3, the second dispersant and carbon nanotubes are added to slurry 1 and uniformly mixed to obtain slurry 2.

20. The manufacturing method according to claim 19, wherein the content a of the first conductive carbon black, the content b of the second conductive carbon black, and the content c of the carbon nanotubes satisfy 0.2 ≤ ((a + b) × c) / (a ​​× b) ≤ 10, where a, b, and c are each based on the total weight of the conductive slurry with respect to its dry weight.

21. A power consumption device comprising a secondary battery according to any one of claims 1 to 12.

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