WO2023179256A1 - 正极组合物、正极浆料、正极极片、二次电池、电池模块、电池包和用电装置 - Google Patents

正极组合物、正极浆料、正极极片、二次电池、电池模块、电池包和用电装置 Download PDF

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WO2023179256A1
WO2023179256A1 PCT/CN2023/076427 CN2023076427W WO2023179256A1 WO 2023179256 A1 WO2023179256 A1 WO 2023179256A1 CN 2023076427 W CN2023076427 W CN 2023076427W WO 2023179256 A1 WO2023179256 A1 WO 2023179256A1
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positive electrode
slurry
battery
cathode
lithium
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PCT/CN2023/076427
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English (en)
French (fr)
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杜香龙
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宁德时代新能源科技股份有限公司
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Publication of WO2023179256A1 publication Critical patent/WO2023179256A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite

Definitions

  • the present application relates to the technical field of secondary batteries, and in particular to a positive electrode composition, positive electrode slurry, positive electrode sheet, secondary battery, battery module, battery pack and electrical device.
  • secondary batteries are widely used in energy storage power systems such as hydraulic, thermal, wind and solar power stations, as well as power tools, transportation, military equipment, aerospace, etc. fields.
  • the present application was made in view of the above-mentioned problems, and an object thereof is to provide a positive electrode composition capable of achieving both low cost and good electrochemical performance in a secondary battery.
  • the present application provides a positive electrode composition, positive electrode slurry, positive electrode sheet, secondary battery, battery module, battery pack and electrical device.
  • the first aspect of the application provides a positive electrode composition for a lithium battery positive electrode, including a positive electrode active material and an anti-aggregation agent, wherein the positive electrode active material includes lithium-containing phosphate, and the anti-agglomeration agent includes phosphorous acid in the molecular chain. polymer groups and ether bonds.
  • the cathode composition of the present application includes a lithium-containing phosphate and the above-mentioned anti-agglomeration agent.
  • the phosphorous acid group in the anti-agglomeration agent can interact with the phosphate in the lithium-containing phosphate through hydrogen bonds, thereby converting the lithium-containing phosphate ""Anchor" on the anti-agglomerant molecular chain.
  • Other parts of the anti-aggregation agent molecular chain can generate strong charge interactions with other molecular chains, causing the anti-agglomeration agent molecular chains to repel each other. In this way, the anti-aggregation agent molecular chains connected to the lithium-containing phosphate can be independently and stably dispersed in the solvent of the positive electrode slurry.
  • the cathode composition of the present application when used in the cathode slurry of secondary batteries, it can effectively reduce the agglomeration of the cathode active material and alleviate the gelation phenomenon of the cathode slurry, thereby reducing the amount of solvent and the back-stirring process. Increase the solid content of the cathode slurry. Therefore, when the cathode composition of the present application is used in secondary batteries, it can reduce the manufacturing cost of secondary batteries, increase the production capacity of secondary batteries, and enable the secondary batteries to maintain good electrochemical performance.
  • the above-mentioned lithium-containing phosphate includes lithium iron phosphate.
  • the particle size D 10 of the lithium iron phosphate is 100 nm to 800 nm. More optionally, the particle size of the lithium iron phosphate is D 10 is 200nm to 300nm, and D 50 is 400nm to 600nm.
  • the cathode composition of the present application includes an anti-aggregation agent and is used in the cathode slurry. Even if the particle size of lithium iron phosphate is within the above-mentioned smaller range, it can effectively reduce the risk of gelation in the cathode slurry.
  • the cathode composition of the present application when used in secondary batteries, it can not only ensure that the secondary batteries have good low-temperature power performance, dynamic performance, and fast charge and discharge performance, but can also reduce the manufacturing cost of the secondary battery and improve the performance of the secondary battery. Secondary battery production capacity.
  • the number average molecular weight of the anti-agglomeration agent is 1,000-10,000, optionally 3,000-8,000.
  • the number average molecular weight of the anti-aggregation agent is within the above-mentioned appropriate range, which can ensure that the anti-agglomeration agent molecular chains connected to the lithium-containing phosphate are independently and stably dispersed in the solvent of the positive electrode slurry, thereby preventing the positive electrode slurry from gelling. phenomenon, thereby reducing the manufacturing cost of secondary batteries and increasing the production capacity of secondary batteries.
  • the anti-agglomeration agent includes a compound represented by Formula 1.
  • m is selected from 20 to 180, and can be an integer from 60 to 150, and n is selected from 25 to 150, and can be an integer from 50 to 120.
  • the phosphorous acid group is located at the end group, and the volume of the molecular chain and the proportion of ether bonds in the molecular chain are both within a suitable range. Therefore, the molecular chains of the anti-aggregation agent can pass through The charges repel each other and are stably dispersed in the solvent of the positive electrode slurry.
  • the anti-agglomeration agent of the present application includes the compound represented by Formula 1, which can further reduce the risk of gel generation in the positive electrode slurry, thereby increasing the production capacity of the secondary battery.
  • the cathode composition further includes carbon nanotubes.
  • the carbon nanotubes are single-walled carbon nanotubes.
  • the positive electrode composition further includes a binder and a conductive agent.
  • the mass proportion of the cathode active material is 93wt% ⁇ 96.9wt%
  • the mass proportion of the anti-aggregation agent is 0.1wt% ⁇ 0.5wt%, optionally 0.3wt% ⁇ 0.5wt%
  • the mass proportion of the binder is 1wt% ⁇ 2wt%
  • the mass proportion of the conductive agent is 2wt% ⁇ 4.5wt%.
  • the mass proportions of the positive electrode active material, anti-aggregation agent, binder and conductive agent are within the above range. When applied to the positive electrode slurry, it can effectively prevent the occurrence of gelation; when used in secondary batteries, it can make the positive electrode plate have Good electronic conductivity and active ion transport capabilities, as well as good structural stability.
  • the positive electrode composition further includes a binder, a conductive agent, and carbon nanotubes.
  • the mass proportion of the cathode active material is 93wt% ⁇ 96wt%
  • the mass proportion of the anti-aggregation agent is 0.1wt% ⁇ 0.5wt%, optionally 0.3wt% ⁇ 0.5 wt%
  • the mass proportion of carbon nanotubes is 0.1wt% ⁇ 1wt%
  • the mass proportion of binder is 1wt% ⁇ 2wt%
  • the mass proportion of conductive agent is 2wt% ⁇ 4wt%.
  • the mass proportions of the positive electrode active material, anti-aggregation agent, carbon nanotubes, binder, and conductive agent are within the above range.
  • it can effectively prevent the occurrence of gelation; when used in the secondary
  • the secondary battery can further improve the electronic conductivity performance, active ion transport capability and structural stability of the positive electrode plate.
  • the mass ratio of lithium-containing phosphate to carbon nanotubes is 1:0.003 ⁇ 1:0.01.
  • the mass ratio of lithium-containing phosphate to carbon nanotubes within the above range can effectively improve the conductive performance of the cathode composition, thereby enabling the secondary battery using the cathode composition of the present application to have low DC resistance (DCR) and long cycle life. .
  • the mass ratio of the lithium-containing phosphate and the anti-aggregation agent is 1:0.003 ⁇ 1:0.006.
  • the mass ratio of lithium-containing phosphate and anti-agglomeration agent is within the above range, which can effectively reduce the gelation phenomenon of the cathode slurry and make the cathode composition have higher energy density, lower cost and good electrochemistry. performance, thus, when used in secondary batteries, it can ensure that the secondary batteries have high productivity, low cost and good electrochemical properties.
  • a second aspect of the application provides a cathode slurry, including a solvent and a cathode composition according to the first aspect of the application.
  • the positive electrode slurry of the present application includes the positive electrode composition of the present application. Therefore, the positive electrode slurry of the present application is not prone to gelation due to the agglomeration of the positive electrode active materials, thereby reducing the amount of solvent and the back-stirring process, improving Solid content of cathode slurry. Therefore, the cathode slurry of the present application is applied to secondary batteries, which can reduce the manufacturing cost of secondary batteries, increase the production capacity of secondary batteries, and enable the secondary batteries to maintain good electrochemical performance.
  • the positive electrode slurry satisfies at least one of the following (1) to (3).
  • the solvent is nitrogen methyl pyrrolidone.
  • the solid component content of the positive electrode slurry is 55wt% to 65wt%.
  • the solid component content of the positive electrode slurry is within an appropriate range, which can facilitate the control of the coating weight and film thickness of the positive electrode piece, thereby taking into account the energy density, electrolyte infiltration rate and electron conduction energy of the positive electrode piece, thereby improving the secondary Electrochemical properties of secondary batteries.
  • the viscosity of the positive electrode slurry is 7000mPa ⁇ s to 15000mPa ⁇ s.
  • the positive electrode slurry has a suitable viscosity, which is conducive to forming a uniform thickness coating on the surface of the positive electrode current collector, thereby improving the efficiency of the positive electrode sheet and increasing the production capacity of the secondary battery.
  • the third aspect of the present application provides a positive electrode sheet, including a positive current collector and a positive electrode and a positive electrode film layer on at least one surface of the current collector.
  • the positive electrode film layer includes the positive electrode composition according to the first aspect of the present application, or the positive electrode film layer is a layer formed after drying the positive electrode slurry according to the second aspect of the present application.
  • the positive electrode film layer includes the positive electrode composition of the present application or is formed by drying the positive electrode slurry of the present application, which can have low preparation cost, high productivity and good electrochemical performance. Therefore, the positive electrode sheet of the present application is applied to secondary batteries, which can reduce the manufacturing cost of secondary batteries, increase the production capacity of secondary batteries, and enable the secondary batteries to maintain good electrochemical performance.
  • a fourth aspect of the present application provides a secondary battery, including the positive electrode plate of the third aspect of the present application.
  • the secondary battery of the present application includes the positive electrode sheet of the present application, thereby having low manufacturing cost, high productivity and good electrochemical performance.
  • a fifth aspect of the present application provides a battery module including the secondary battery of the fourth aspect of the present application.
  • a sixth aspect of the present application provides a battery pack, including the battery module of the fifth aspect of the present application.
  • a seventh aspect of the present application provides an electrical device, including at least one selected from the secondary battery of the fourth aspect of the present application, the battery module of the fifth aspect of the present application, or the battery pack of the sixth aspect of the present application. kind.
  • the battery modules, battery packs and electrical devices of the present application include the secondary battery provided by the present application, and therefore have at least the same advantages as the secondary batteries of the present application.
  • FIG. 1 is a schematic diagram of the state in which the positive electrode composition exists in the positive electrode slurry in one embodiment of the positive electrode composition of the present application.
  • FIG. 2 is a schematic diagram of an embodiment of a secondary battery of the present application.
  • FIG. 3 is an exploded view of the embodiment of the secondary battery of the present application shown in FIG. 2 .
  • FIG. 4 is a schematic diagram of an embodiment of the battery module of the present application.
  • FIG. 5 is a schematic diagram of an embodiment of the battery pack of the present application.
  • FIG. 6 is an exploded view of the battery pack of the present application shown in FIG. 5 .
  • FIG. 7 is a schematic diagram of a power consumption device using a secondary battery according to an embodiment of the present application as a power source.
  • Figure 8 is a low-temperature power test chart of the secondary battery in Example 1 of the present application.
  • Figure 9 is a low-temperature power test chart of the secondary battery of Comparative Example 1 of the present application.
  • Ranges disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the endpoints, and may be arbitrarily combined, that is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, understand that ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5.
  • the numerical range “a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range “0-5" means that all real numbers between "0-5" have been listed in this article, and "0-5" is just an abbreviation of these numerical combinations.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • step (c) means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c). , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b), etc.
  • condition "A or B” is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; Or both A and B are true (or exist).
  • the cathode slurry is usually placed in a stirring tank and continuously stirred slowly. After the gelation phenomenon occurs, the solvent is added for back-stirring and viscosity adjustment.
  • the positive electrode slurry cannot be stirred back in the transportation pipeline, and gelation is likely to occur in the transportation pipeline.
  • back stirring and viscosity adjustment will increase the amount of solvent used, thereby increasing the manufacturing cost of secondary batteries.
  • the inventor has provided a positive electrode composition, positive electrode slurry, positive electrode sheet, secondary battery, battery module, battery pack and electrical device after in-depth consideration.
  • the first aspect of this application proposes a positive electrode composition that can be used in lithium batteries.
  • the positive electrode composition includes a positive electrode active material and an anti-aggregation agent.
  • the positive active material includes lithium-containing phosphate
  • the anti-aggregation agent includes a polymer containing a phosphite group and an ether bond in the molecular chain.
  • the molecular chain of the above-mentioned anti-aggregation agent there can be one or more phosphorous acid groups, and the phosphorous acid groups can be end groups or groups in the branch chain; the ether bonds can be one or more, and the ether bonds can be one or more.
  • the bond can be at the end of the chain, in a segment of the main chain, or in a branch chain.
  • ether bonds may be included in the repeating units of the molecular chain.
  • the cathode composition of the present application includes lithium-containing phosphate and the above-mentioned anti-aggregation agent, and when applied to the cathode slurry, it can effectively prevent the cathode slurry from collapsing during the standing process. As well as gelation in the delivery pipeline.
  • the phosphorous acid group can interact with the phosphate group in the lithium-containing phosphate through hydrogen bonds, thereby converting the lithium-containing phosphate into the lithium-containing phosphate.
  • the phosphate is "anchored" to the anti-agglomerant molecular chain.
  • the agent molecular chains can be independently and stably dispersed in the solvent of the positive electrode slurry, and play a role in preventing the gelation phenomenon of the positive electrode slurry.
  • the cathode composition of the present application is applied to cathode slurry, and the resulting cathode slurry does not produce gelation even if it is left standing for 48 hours.
  • the anti-agglomeration agent of the present application is used in the cathode slurry, the electrochemical performance of the prepared secondary battery is almost unaffected, and the secondary battery can maintain good electrochemical performance.
  • the cathode composition of the present application includes lithium-containing phosphate and an anti-aggregation agent.
  • an anti-aggregation agent When used in the cathode slurry of secondary batteries, it can effectively reduce the agglomeration of cathode active materials, alleviate the gelation phenomenon of the cathode slurry, and thereby reduce the amount of solvents.
  • the dosage and back-stirring process increase the solid content of the cathode slurry. Therefore, the cathode composition of the present application is applied to secondary batteries and can reduce the manufacturing cost of secondary batteries. Improve the production capacity of secondary batteries and maintain good electrochemical properties of secondary batteries.
  • the lithium-containing phosphate may include lithium iron phosphate.
  • the particle size D 10 of lithium iron phosphate can be 100nm ⁇ 800nm, 100nm ⁇ 700nm, 100nm ⁇ 600nm, 100nm ⁇ 500nm, 100nm ⁇ 400nm, 100nm ⁇ 300nm, 100nm ⁇ 200nm, 200nm ⁇ 800nm, 200nm ⁇ 700nm m, 4 00nm ⁇ 700nm, 400nm ⁇ 600nm, 400nm ⁇ 500nm, 500nm ⁇ 800nm, 500nm ⁇ 700nm, 500nm ⁇ 600nm, 600nm ⁇ 800nm, 600nm ⁇ 700nm or 700nm ⁇ 800nm.
  • the particle size D 10 of lithium iron phosphate can be 200nm ⁇ 300nm
  • D 50 can be 400nm ⁇ 600nm, 450nm ⁇ 600nm, 500nm ⁇ 600nm, 550nm ⁇ 600nm, 400nm ⁇ 550nm, 450nm ⁇ 550nm, 500nm ⁇ 550nm , 400nm ⁇ 500nm, 450nm ⁇ 500nm, 400nm ⁇ 450nm.
  • the particle diameters D 10 and D 50 of lithium iron phosphate have meanings known in the art.
  • D 10 can refer to the particle diameter with a cumulative distribution of particles of 10%, that is, the volume content of particles smaller than this particle diameter value accounts for all 10% of particles.
  • D50 may refer to the particle size at which the cumulative distribution of particles is 50%.
  • D 10 and D 50 can be determined using methods and instruments known in the art. For example, you can refer to GB/T 19077-2016 particle size distribution laser diffraction method and use a laser particle size analyzer (such as Malvern Mastersizer 2000E, UK) to measure it.
  • Lithium iron phosphate is used as a positive active material in secondary batteries, which can enable secondary batteries to have good low-temperature power performance, dynamic performance, and fast charge and discharge performance. Without intending to be limited by any theory or explanation, the inventor found that when the particle size of lithium iron phosphate is within the above-mentioned smaller range, the performance improvement of the secondary battery is more significant. However, as the particle size of lithium iron phosphate decreases, the possibility of agglomeration of lithium iron phosphate particles in the cathode slurry also increases.
  • the cathode composition of the present application includes an anti-aggregation agent and is used in the cathode slurry.
  • the cathode composition of the present application when used in secondary batteries, it can not only ensure that the secondary batteries have good low-temperature power performance, dynamic performance, and fast charge and discharge performance, but can also reduce the manufacturing cost of the secondary battery and improve the performance of the secondary battery. Secondary battery production capacity.
  • the number average molecular weight of the anti-agglomeration agent can be 1000-10000, 2000-9000, 3000-8000, 4000-7000, 5000-6000.
  • the inventor found that the number average molecular weight of the anti-agglomeration agent within the above-mentioned appropriate range is not only conducive to the generation of hydrogen between the phosphite group in the anti-agglomeration agent and the lithium-containing phosphate.
  • the bond is also conducive to the mutual dispersion of the anti-agglomerant molecular chains. This ensures that the anti-aggregation agent molecular chains connected to the lithium-containing phosphate are independently and stably dispersed in the solvent of the positive electrode slurry, thereby preventing the positive electrode slurry from gelling, thereby reducing the manufacturing cost of secondary batteries. Increase the production capacity of secondary batteries.
  • the anti-agglomeration agent may include a compound represented by Formula 1.
  • m may be selected from 20 to 180, 30 to 170, 40 to 160, 50 to 150, 60 to 150, 70 to 150 ,
  • An integer of 80 to 150, n is selected from an integer of 25 to 150, 30 to 140, 40 to 130, and 50 to 120.
  • the compound represented by Formula 1 can be obtained in a variety of ways.
  • the compound represented by Formula 1 can be self-produced.
  • the compound represented by Formula 1 can be prepared through the following steps S1 to S3.
  • the alkylene oxides include ethylene oxide.
  • the inventor found that in the compound represented by Formula 1, the phosphorous acid group is located at the terminal group, which is conducive to the formation of hydrogen bonds with the lithium-containing phosphate.
  • the values of m and n are within the above range, which can make the volume of the molecular chain and the proportion of ether bonds in the molecular chain within appropriate ranges.
  • the molecular chains of the anti-aggregation agent can repel each other through charge interactions, thereby being stably dispersed in the solvent of the positive electrode slurry.
  • the anti-agglomeration agent of the present application includes the compound represented by Formula 1, which can further reduce the risk of gel generation in the positive electrode slurry, thereby increasing the production capacity of the secondary battery.
  • the cathode composition may further include carbon nanotubes (CNTs), specifically single-walled carbon nanotubes (SWCNTs) and/or multi-walled carbon nanotubes (MWCNTs).
  • CNTs carbon nanotubes
  • SWCNTs specifically single-walled carbon nanotubes
  • MWCNTs multi-walled carbon nanotubes
  • the carbon nanotubes may be single-walled carbon nanotubes (SWCNT).
  • the inventors conducted in-depth research after solving the problem that the positive electrode slurry is prone to gelation when left standing.
  • the inventor unexpectedly discovered that including carbon nanotubes in the cathode composition of the present application can significantly enhance the conductive properties of the cathode composition, thereby reducing the impedance of the cathode composition, thereby fully Leverage the low-temperature power performance of lithium-containing phosphates.
  • the phosphorous acid group 021 in the molecular chain of the anti-aggregation agent 02 can "anchor" the lithium-containing phosphoric acid on the surface of the cathode active material 01 Salt molecules, and the adjacent "anchored" cathode active material 01 exists stably and independently due to the repulsion between the molecular chains of the anti-aggregation agent 02.
  • the molecular chains of carbon nanotubes 03 and anti-aggregation agent 02 have a certain degree of flexibility.
  • carbon nanotubes 03 When dispersed in a solvent, carbon nanotubes 03 can be dispersed and wrapped around the molecular chains of anti-aggregation agent 02, thereby improving the conductivity of the cathode composition. received significant improvement.
  • single-walled carbon nanotubes have a larger aspect ratio than multi-walled carbon nanotubes and are more likely to be entangled in the molecular chains of the anti-aggregation agent 02
  • when single-walled carbon nanotubes are included in the positive electrode composition Can further improve the positive electrode group conductive properties of the compound. Therefore, when the cathode composition of the present application includes carbon nanotubes and is used in the cathode slurry, the prepared secondary battery not only has the characteristics of high productivity and low cost, but also has excellent low-temperature power performance.
  • the positive electrode composition may further include a binder and a conductive agent.
  • the mass proportion of the cathode active material can be 93wt% ⁇ 96.9wt%
  • the mass proportion of the anti-aggregation agent can be 0.1wt% ⁇ 0.5wt%, 0.2wt% ⁇ 0.5 wt% or 0.3wt%-0.5wt%
  • the mass proportion of the binder can be 1wt%-2wt%
  • the mass proportion of the conductive agent can be 2wt%-4.5wt%.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene tripolymer.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • vinylidene fluoride-tetrafluoroethylene-propylene terpolymer vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene tripolymer.
  • the conductive agent can include superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, At least one of graphene and carbon nanofibers.
  • the mass proportions of the positive electrode active material, anti-agglomeration agent, binder, and conductive agent are within the above range.
  • gelation can be effectively prevented.
  • the occurrence of the phenomenon; applied to secondary batteries, it can make the positive electrode plate have good electronic conductivity and active ion transmission capabilities, as well as good structural stability. This can increase the production capacity of the secondary battery and ensure that the secondary battery has good electrochemical performance.
  • the cathode composition further includes a binder, a conductive agent, and carbon nanotubes.
  • the mass proportion of the cathode active material may be 93wt% ⁇ 96wt%
  • the mass proportion of the anti-aggregation agent may be 0.1wt% ⁇ 0.5wt%, 0.2wt% ⁇ 0.5wt % or 0.3wt% ⁇ 0.5wt%
  • the mass proportion of carbon nanotubes can be 0.1wt% ⁇ 1wt%
  • the mass proportion of binder can be 1wt% ⁇ 2wt%
  • the mass proportion of conductive agent can be 2wt % ⁇ 4wt%.
  • binder and conductive agent examples are as described above and will not be described again here.
  • the mass proportions of the positive electrode active material, anti-aggregation agent, carbon nanotubes, binder, and conductive agent are within the above range, and when applied to the positive electrode slurry, it can Effectively prevents the occurrence of gel phenomenon; used in secondary batteries, it can make the positive electrode plate have good electronic conductivity and active ion transmission capabilities, as well as good structural stability. This can increase the production capacity of the secondary battery and ensure that the secondary battery has good electrochemical performance.
  • the mass ratio of lithium-containing phosphate to carbon nanotubes is 1:0.003 to 1:0.01, for example, it can be 1:0.003, 1:0.004, 1:0.005, 1:0.006, 1:0.007, 1:0.008, 1:0.009, 1:0.01.
  • the mass ratio of lithium-containing phosphate to carbon nanotubes within the above range can effectively improve the conductive performance of the cathode composition, thereby enabling secondary batteries using the cathode composition of the present application.
  • DCR DC resistance
  • the mass ratio of the lithium-containing phosphate to the anti-agglomeration agent may be 1:0.003 ⁇ 1:0.006, for example, it may be 1:0.003, 1:0.004, 1:0.005, or 1:0.006.
  • the mass ratio of lithium-containing phosphate to anti-aggregation agent is within the above range, the gelation phenomenon of the positive electrode slurry can be effectively reduced, while the positive electrode composition has higher energy density, lower cost and good electrochemical performance. Therefore, it can be used in secondary batteries. It can ensure that the secondary battery has high productivity, low cost and good electrochemical performance.
  • a second aspect of the present application provides a positive electrode slurry, including a solvent and the positive electrode composition of the present application.
  • the above-mentioned solvent may be nitrogen methylpyrrolidone (NMP).
  • the solid component content of the cathode slurry may range from 55 wt% to 65 wt%.
  • the solid component content of the positive electrode slurry is within an appropriate range, which can facilitate the control of the coating weight and film thickness of the positive electrode piece, thereby taking into account the energy density, electrolyte infiltration rate and electron conduction energy of the positive electrode piece, thereby improving the secondary Electrochemical properties of secondary batteries.
  • the viscosity of the cathode slurry may range from 7000 mPa ⁇ s to 15000 mPa ⁇ s.
  • the positive electrode slurry has a suitable viscosity, which is conducive to forming a uniform thickness coating on the surface of the positive electrode current collector, thereby improving the efficiency of the positive electrode sheet and increasing the production capacity of the secondary battery.
  • the present application also provides a method for preparing the positive electrode slurry of the present application, which includes: uniformly mixing the positive electrode material including the positive electrode composition of the present application and a solvent to obtain the positive electrode slurry.
  • uniformly mixing the positive electrode material including the positive electrode composition of the present application and the solvent may include mixing each component in the positive electrode composition uniformly and then mixing it with the solvent; it may also include Mix each component in the positive electrode composition with the solvent in a certain order.
  • the positive active material, conductive agent, binder and solvent can be mixed evenly, then carbon nanotubes and anti-aggregation agent can be added, and then the solvent can be added to adjust the slurry viscosity.
  • the solvent may be nitrogen methylpyrrolidone (NMP).
  • the solid component content of the cathode slurry may be 55wt% ⁇ 65wt%.
  • the solid component content of the positive electrode slurry is within an appropriate range, which can facilitate the control of the coating weight and film thickness of the positive electrode piece, thereby taking into account the energy density, electrolyte infiltration rate and electron conduction energy of the positive electrode piece, thereby improving the secondary Electrochemical properties of secondary batteries.
  • the viscosity of the cathode slurry may range from 7000 mPa ⁇ s to 15000 mPa ⁇ s.
  • the positive electrode slurry has a suitable viscosity, which is conducive to forming a uniform thickness coating on the surface of the positive electrode current collector, thereby improving the efficiency of the positive electrode sheet and increasing the production capacity of the secondary battery.
  • a third aspect of the present application provides a positive electrode sheet, including a positive electrode current collector and a positive electrode film layer located on at least one surface of the positive electrode current collector, wherein the positive electrode film layer includes the positive electrode composition according to the application, or the The positive electrode film layer is a layer formed after drying the positive electrode slurry of the present application.
  • the positive electrode current collector has two surfaces facing each other in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • the metal foil aluminum foil can be used.
  • 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 base layer.
  • Composite current collectors can be made by combining metal materials Materials (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) are formed on polymer material substrates (such as polypropylene (PP), polyethylene terephthalate (PET) , polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode sheet can be prepared in the following manner: dispersing the positive electrode composition of the present application and optional other components in a solvent (such as NMP) to form a positive electrode slurry, or directly using the positive electrode composition of the present application. Positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode piece can be obtained.
  • a solvent such as NMP
  • the substances contained in the positive electrode film layer can be tested during the battery preparation process, or by sampling from the prepared secondary battery.
  • the testing method can be a method known in the art, for example, by Scanning electron microscopy for testing.
  • a secondary battery is provided.
  • a secondary battery typically includes a positive electrode plate, a negative electrode plate, an electrolyte and a separator.
  • active ions are inserted and detached back and forth between the positive and negative electrodes.
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the isolation film is placed between the positive electrode piece and the negative electrode piece. It mainly prevents the positive and negative electrodes from short-circuiting and allows ions to pass through.
  • the positive electrode plate is selected from the group consisting of positive electrode plates according to the third aspect of the application.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, where the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two opposite surfaces in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • 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 base material.
  • the composite current collector can be formed by forming metal materials (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative active material may be a negative active material known in the art for batteries.
  • the negative active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and the like.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon carbon composites, silicon nitrogen composites and silicon alloys.
  • the tin-based material may be selected from at least one of elemental tin, tin oxide compounds and tin alloys.
  • the present application is not limited to these materials, and other traditional materials that can be used as battery negative electrode active materials can also be used. Only one type of these negative electrode active materials may be used alone, or two or more types may be used in combination.
  • the negative electrode film layer optionally further includes a binder.
  • the binder can be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), polysodium acrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), poly At least one of methacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer optionally further 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.
  • the negative electrode film layer optionally includes other auxiliaries, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.
  • thickeners such as sodium carboxymethylcellulose (CMC-Na)
  • the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative active materials, conductive agents, binders and any other components in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode piece can be obtained.
  • a solvent such as deionized water
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the type of electrolyte in this application can be selected according to needs.
  • the electrolyte can be liquid, gel, or completely solid.
  • the electrolyte is an electrolyte solution.
  • the electrolyte solution includes electrolyte salts and solvents.
  • the electrolyte salt may be selected from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonimide, lithium bistrifluoromethanesulfonimide, trifluoromethane At least one of lithium sulfonate, lithium difluorophosphate, lithium difluoroborate, lithium dioxaloborate, lithium difluorodioxalate phosphate and lithium tetrafluoroxalate phosphate.
  • the solvent may be selected from the group consisting of ethylene carbonate, propylene carbonate, methylethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, Butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate At least one of ester, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the electrolyte optionally further includes additives.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.
  • the secondary battery further includes a separator film.
  • a separator film There is no particular restriction on the type of isolation membrane in this application. Any well-known porous structure isolation membrane with good chemical stability and mechanical stability can be used.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation film can be a single-layer film or a multi-layer composite film, with no special restrictions. When the isolation film is a multi-layer composite film, the materials of each layer can be the same or different, and there is no particular limitation.
  • the positive electrode piece, the negative electrode piece and the separator film can be made into an electrode assembly through a winding process or a lamination process.
  • the secondary battery may include an outer packaging.
  • the outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the material of the soft bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
  • FIG. 2 shows a square-structured secondary battery 5 as an example.
  • the outer package may include a housing 51 and a top cover assembly 53 .
  • the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity.
  • the housing 51 has an opening communicating with the accommodating cavity, and the top cover assembly 53 can cover the opening to close the accommodating cavity.
  • the positive electrode piece, the negative electrode piece and the isolation film can be formed into the electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the containing cavity.
  • the electrolyte soaks into the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • secondary batteries can be assembled into battery modules, and the number of secondary batteries contained in the battery module can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery module.
  • FIG. 4 is a battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of secondary batteries 5 can be fixed by fasteners.
  • the battery module 4 may further include a housing having a receiving space in which a plurality of secondary batteries 5 are received.
  • the above-mentioned battery modules can also be assembled into a battery pack.
  • the number of battery modules contained in the battery pack can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box 2 and a lower box 3 .
  • the upper box 2 can be covered with the lower box 3 and form a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided by the present application.
  • the secondary battery and battery mold The block or battery pack can be used as a power source for the electrical device or as an energy storage unit for the electrical device.
  • the electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, and electric golf carts). , electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.
  • a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.
  • Fig. 7 is an electrical device as an example.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc.
  • a battery pack or battery module can be used.
  • the power-consuming device may be a mobile phone, a tablet computer, a laptop computer, etc.
  • the device is usually required to be thin and light, and a secondary battery can be used as a power source.
  • the anti-agglomeration agent used in each embodiment is selected from the compounds shown in Formula 1.
  • the particle size D 10 of lithium iron phosphate, the proportion w 1 of lithium iron phosphate in the solid component content of the positive electrode slurry, the number average molecular weight M n of the anti-agglomeration agent, and the proportion of the anti-agglomeration agent in the positive electrode slurry The proportion w 2 in the solid component content, and the mass ratio of anti-agglomeration agent to lithium iron phosphate
  • the type of CNT, the proportion w 3 of CNT in the solid component content of the cathode slurry, and the mass ratio of CNT to lithium iron phosphate As shown in Table 1.
  • the prepared positive electrode slurry is evenly coated on the positive electrode current collector, and then dried, cold pressed, and cut to obtain positive electrode sheets.
  • Ionized water mix evenly to prepare negative electrode slurry; apply the negative electrode slurry one or more times evenly on the negative electrode current collector copper foil, dry, cold press, and cut to obtain negative electrode pieces.
  • the electrode assembly is put into an aluminum shell, baked at 100°C to remove water, and then the electrolyte is injected and sealed to obtain an uncharged battery.
  • the uncharged battery then goes through processes such as standing, hot and cold pressing, formation, shaping, and capacity testing to obtain a secondary battery.
  • the number average molecular weight of the anti-aggregation agent is within the range of the present application, and it can effectively reduce the gel degree of the positive electrode slurry, and as the amount of anti-agglomeration agent added increases , the gel degree of the positive electrode slurry decreases. It can be seen from Examples 3 and 13 to 17 that including carbon nanotubes, especially single-walled carbon nanotubes, in the positive slurry can significantly improve the low-temperature power performance of the secondary battery.
  • the positive electrode slurry in Comparative Examples 1 to 3 does not include an anti-agglomeration agent. After being left for 48 hours, the viscosity of the positive electrode slurry increases significantly. As a result, the production capacity and manufacturing cost of the secondary battery are compared with those in the Examples. 1 to 17 are not ideal.

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Abstract

本申请提供了一种正极组合物、正极浆料、正极极片、二次电池、电池模块、电池包和用电装置。该正极组合物，包括正极活性材料和防凝聚剂，其中，正极活性材料包括含锂磷酸盐，防凝聚剂包括分子链中包含亚磷酸基团和醚键的聚合物。

Description

正极组合物、正极浆料、正极极片、二次电池、电池模块、电池包和用电装置
相关申请的交叉引用
本申请要求享有于2022年03月22日提交的名称为“正极组合物、正极浆料、正极极片、二次电池、电池模块、电池包和用电装置”的中国专利申请202210282381.1的优先权，该申请的全部内容通过引用并入本文中。
技术领域
本申请涉及二次电池技术领域，尤其涉及一种正极组合物、正极浆料、正极极片、二次电池、电池模块、电池包和用电装置。
背景技术
近年来，随着二次电池的应用范围越来越广泛，二次电池广泛应用于水力、火力、风力和太阳能电站等储能电源系统，以及电动工具、交通工具、军事装备、航空航天等多个领域。
随着二次电池市场地位的提升，人们不仅期望二次电池具有更高的能量密度、更好的循环性能，还期望二次电池具有更低的制造成本、更高的产能。
但是，目前在二次电池的产业化生产的过程中，不可避免地会产生一些材料的损失，由此导致了二次电制造成本的增加、降低了二次电池的产能。
发明内容
本申请是鉴于上述课题而进行的，其目的在于，提供一种能够使二次电池兼具低成本和良好的电化学性能的正极组合物。
为了达到上述目的，本申请提供了一种正极组合物、正极浆料、正极极片、二次电池、电池模块、电池包和用电装置。
本申请的第一方面提供了一种用于锂电池正极的正极组合物，包括正极活性材料和防凝聚剂，其中，正极活性材料包括含锂磷酸盐，防凝聚剂包括分子链中包含亚磷酸基团和醚键的聚合物。
本申请的正极组合物中包括含锂磷酸盐和上述防凝聚剂，防凝聚剂中的亚磷酸基团可以与含锂磷酸盐中的磷酸根通过氢键相互作用，从而将含锂磷酸盐“锚固”在防凝聚剂分子链上。防凝聚剂分子链中的其他部分可以与其他分子链之间产生强电荷作用，从而使得防凝聚剂分子链之间相互排斥， 进而使得连接有含锂磷酸盐的防凝聚剂分子链能够相互独立、稳定地分散在正极浆料的溶剂中。由此，本申请的正极组合物应用于二次电池的正极浆料中，能够有效减少正极活性材料的团聚、缓解正极浆料的凝胶现象，从而能够减少溶剂的用量和回搅的工序、提升正极浆料的固含量。由此，本申请的正极组合物应用于二次电池，能够降低二次电池的制造成本、提高二次电池的产能，并使得二次电池保持良好的电化学性能。
在本申请第一方面的任意实施方式中，上述含锂磷酸盐包括磷酸铁锂，可选地，磷酸铁锂的粒径D10为100nm～800nm，更可选地，磷酸铁锂的粒径D10为200nm～300nm，D50为400nm～600nm。本申请的正极组合物中包括防凝聚剂，应用于正极浆料中，即使磷酸铁锂的粒径在上述较小的范围内，也能够有效降低正极浆料产生凝胶现象的风险。由此，本申请的正极组合物应用于二次电池，不仅能够保证二次电池具备良好的低温功率性能、动力学性能和快充快放性能，还能够降低二次电池的制造成本、提高二次电池的产能。
在本申请第一方面的任意实施方式中，防凝聚剂的数均分子量为1000～10000、可选为3000～8000。防凝聚剂的数均分子量在上述合适的范围内，能够保证连接有含锂磷酸盐的防凝聚剂分子链相互独立、稳定地分散在正极浆料的溶剂中，从而防止正极浆料产生凝胶现象，进而降低二次电池的制造成本、提高二次电池的产能。
在本申请第一方面的任意实施方式中，防凝聚剂包括式1所示的化合物。
在式1中，m选自20～180、可选为60～150的整数，n选自25～150、可选为50～120的整数。式1所示的化合物中，亚磷酸基团位于端基，并且分子链的体积以及醚键在分子链中的占比都处于合适的范围，由此，防凝聚剂的分子链之间能够通过电荷作用相互排斥，从而稳定地分散在正极浆料的溶剂中。本申请的防凝聚剂包括式1所示的化合物，能够进一步降低正极浆料产生凝胶的风险，从而提高二次电池的产能。
在本申请第一方面的任意实施方式中，正极组合物还包括碳纳米管。可选地，碳纳米管为单壁碳纳米管。本申请的正极组合物中包括碳纳米管时，应用于正极浆料中，能够使得制备得到的二次电池不仅具有高产能、低成本的特点，还具有优异的低温功率性能。
在本申请第一方面的任意实施方式中，正极组合物还包括粘结剂和导电剂。可选地，基于正极组合物的总质量，正极活性材料的质量占比为93wt％～96.9wt％，防凝聚剂的质量占比为0.1wt％～0.5wt％、可选为0.3wt％～0.5wt％，粘结剂的质量占比为1wt％～2wt％，导电剂的质量占比为 2wt％～4.5wt％。正极活性材料、防凝聚剂、粘结剂、导电剂的质量占比在上述范围内，应用于正极浆料，能够有效防止凝胶现象的产生；应用于二次电池，能够使得正极极片具有良好电子传导性能和活性离子传输能力，以及良好的结构稳定性。
在本申请第一方面的任意实施方式中，正极组合物还包括粘结剂、导电剂和碳纳米管。可选地，基于正极组合物的总质量，正极活性材料的质量占比为93wt％～96wt％，防凝聚剂的质量占比为0.1wt％～0.5wt％、可选为0.3wt％～0.5wt％，碳纳米管的质量占比为0.1wt％～1wt％，粘结剂的质量占比为1wt％～2wt％，导电剂的质量占比为2wt％～4wt％。正极组合物中，正极活性材料、防凝聚剂、碳纳米管、粘结剂、导电剂的质量占比在上述范围内，应用于正极浆料，能够有效防止凝胶现象的产生；应用于二次电池，能够进一步提高正极极片的电子传导性能、活性离子传输能力以及结构稳定性。
在本申请第一方面的任意实施方式中，正极组合物中，含锂磷酸盐与碳纳米管的质量比为1:0.003～1:0.01。含锂磷酸盐与碳纳米管的质量比在上述范围内，能够有效提升正极组合物的导电性能，从而能够使得应用本申请正极组合物的二次电池具有低直流电阻(DCR)、长循环寿命。
在本申请第一方面的任意实施方式中，正极组合物中，含锂磷酸盐与防凝聚剂的质量比为1:0.003～1:0.006。含锂磷酸盐与防凝聚剂的质量比在上述范围内，能够在有效减少正极浆料的凝胶现象的同时，使得正极组合物具有更高的能量密度、更低的成本以及良好的电化学性能，由此，应用于二次电池中，能够保证二次电池具有高产能、低成本和良好的电化学性能。
本申请的第二方面提供一种正极浆料，包括溶剂以及根据本申请第一方面的正极组合物。
本申请的正极浆料中包括本申请的正极组合物，由此，本申请的正极浆料不易因为正极活性材料的团聚而产生凝胶现象，从而能够减少溶剂的用量和回搅的工序、提升正极浆料的固含量。由此，本申请的正极浆料应用于二次电池，能够降低二次电池的制造成本、提高二次电池的产能，并使得二次电池保持良好的电化学性能。
在本申请第二方面的任意实施方式中，正极浆料满足如下(1)～(3)中的至少一者。
(1)溶剂为氮甲基吡咯烷酮。
(2)正极浆料的固体组分含量为55wt％～65wt％。正极浆料的固体组分含量在合适的范围内，能够便于控制正极极片的涂布重量和膜层厚度，从而兼顾正极极片的能量密度、电解液浸润速率和电子传导能量，进而提高二次电池的电化学性能。
(3)正极浆料的粘度为7000mPa·s～15000mPa·s。正极浆料具有合适的粘度，有利于在正极集流体的表面形成厚度均一的涂层，从而提高正极极片的优率、提高二次电池的产能。
本申请的第三方面提供一种正极极片，包括正极集流体以及位于正极 集流体至少一个表面上的正极膜层。其中，正极膜层包括根据本申请第一方面的正极组合物、或正极膜层为根据本申请第二方面的正极浆料干燥后形成的层。
本申请的正极极片中，正极膜层包括本申请的正极组合物、或由本申请的正极浆料干燥后形成，能够具有低制备成本、高产能和良好的电化学性能。由此，本申请的正极极片应用于二次电池，能够降低二次电池的制造成本、提高二次电池的产能，并使得二次电池保持良好的电化学性能。
本申请的第四方面提供一种二次电池，包括本申请第三方面的正极极片。
本申请的二次电池包括本申请的正极极片，由此能够具有低制造成本、高产能和良好的电化学性能。
本申请的第五方面提供一种电池模块，包括本申请的第四方面的二次电池。
本申请的第六方面提供一种电池包，包括本申请的第五方面的电池模块。
本申请的第七方面提供一种用电装置，包括选自本申请的第四方面的二次电池、本申请的第五方面的电池模块或本申请的第六方面的电池包中的至少一种。
本申请的电池模块、电池包和用电装置包括本申请提供的二次电池，因而至少具有与本申请的二次电池相同的优势。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对本申请实施例中所需要使用的附图作简单地介绍，显而易见地，下面所描述的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据附图获得其他的附图。
图1是本申请的正极组合物的一实施方式中，正极组合物在正极浆料中存在状态的示意图。
图2是本申请二次电池的实施方式的示意图。
图3是图2所示的本申请的二次电池的实施方式的分解图。
图4是本申请的电池模块的一实施方式的示意图。
图5是本申请的电池包的一实施方式的示意图。
图6是图5所示的本申请的电池包的实施方式分解图。
图7是本申请的二次电池的实施例用作电源的用电装置的示意图。
图8是本申请实施例1的二次电池的低温功率测试图。
图9是本申请对比例1的二次电池的低温功率测试图。
附图标记说明：
01正极活性材料；02防凝聚剂；03碳纳米管；021亚磷酸基团；1电池包；2上箱体；3下箱体；4电池模块；5二次电池；51壳体；52电极组 件；53顶盖组件。
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的正极组合物、正极浆料、正极极片、二次电池、电池模块、电池包和用电装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
随着二次电池的发展，人们期望二次电池在具有良好的电化学性能的同时，能够具有更低的制造成本和更高的产能。从二次电池的制造层面看，各个工序均对二次电池的制造成本、产能具有重要的影响。
发明人经研究发现，现有的正极极片的制造工序中，存在着较为严重的原料损耗，生产效率也较低。具体地，发明人发现，在二次电池的产业化生产中，正极浆料制备完成后，通常需要放置一段时间再送经输送管道，以用于涂布形成正极膜层。由于正极材料的粒径较小，制备得到的正极浆料中存在着大量的纳米微粉，这些纳米微粉容易团聚而出现凝胶。
目前，为了缓解正极浆料的凝胶现象，通常是将正极浆料放置于搅拌罐中进行持续慢搅，出现凝胶现象后再加入溶剂进行回搅和调粘。但是，在输送管道中无法对正极浆料进行回搅，在输送管道中容易产生凝胶现象。此外，回搅和调粘会增加溶剂的用量，从而增加了二次电池的制造成本。
鉴于此，发明人经深入思考，提供了一种正极组合物、正极浆料、正极极片、二次电池、电池模块、电池包和用电装置。
正极组合物
本申请第一方面提出了一种正极组合物，可用于锂电池。该正极组合物包括正极活性材料和防凝聚剂。其中，正极活性材料包括含锂磷酸盐，防凝聚剂包括分子链中包含亚磷酸基团和醚键的聚合物。
在上述防凝聚剂的分子链中，亚磷酸基团可以为一个或多个，亚磷酸基团可以为端基，也可以为支链中的基团；醚键可以为一个或多个，醚键可以位于链端，也可以位于主链的链段中，还可以位于支链。可选的，醚键可以包含于分子链的重复单元中。
虽然机理尚不明确，但本申请人意外地发现：本申请的正极组合物中包括含锂磷酸盐和上述防凝聚剂，应用于正极浆料中，能够有效防止正极浆料在静置过程中以及在输送管道中产生凝胶现象。
具体地，并非意在受限于任何理论或解释，发明人发现，本申请的防凝聚剂中，亚磷酸基团可以与含锂磷酸盐中的磷酸根通过氢键相互作用，从而将含锂磷酸盐“锚固”在防凝聚剂分子链上。防凝聚剂分子链中的其他部分，尤其是醚键，会与其他分子链之间产生强电荷作用，从而使得防凝聚剂分子链之间相互排斥，进而使得连接有含锂磷酸盐的防凝聚剂分子链能够相互独立、稳定地分散在正极浆料的溶剂中，发挥防止正极浆料产生凝胶现象的作用。在一些实施例中，本申请的正极组合物应用于正极浆料，得到的正极浆料即使静置48h也不会产生凝胶现象。此外，本申请的防凝聚剂应用于正极浆料中，制备得到的二次电池的电化学性能几乎不受影响，能够使得二次电池保持良好的电化学性能。
本申请的正极组合物中包括含锂磷酸盐和防凝聚剂，应用于二次电池的正极浆料中，能够有效减少正极活性材料的团聚、缓解正极浆料的凝胶现象，从而能够减少溶剂的用量和回搅的工序、提升正极浆料的固含量。由此，本申请的正极组合物应用于二次电池，能够降低二次电池的制造成本、 提高二次电池的产能，并使得二次电池保持良好的电化学性能。
在一些实施方式中，含锂磷酸盐可包括磷酸铁锂。可选地，磷酸铁锂的粒径D10可为100nm～800nm，100nm～700nm，100nm～600nm，100nm～500nm，100nm～400nm，100nm～300nm，100nm～200nm，200nm～800nm，200nm～700nm，200nm～600nm，200nm～500nm，200nm～400nm，200nm～300nm，300nm～800nm，300nm～700nm，300nm～600nm，300nm～500nm，300nm～400nm，400nm～800nm，400nm～700nm，400nm～600nm，400nm～500nm，500nm～800nm，500nm～700nm，500nm～600nm，600nm～800nm，600nm～700nm或700nm～800nm。更可选地，磷酸铁锂的粒径D10可为200nm～300nm，D50可为400nm～600nm，450nm～600nm，500nm～600nm，550nm～600nm，400nm～550nm，450nm～550nm，500nm～550nm，400nm～500nm，450nm～500nm，400nm～450nm。
本申请中，磷酸铁锂的粒径D10和D50具有本领域公知的含义，其中，D10可以指颗粒累积分布为10％的粒径，即小于此粒径值的颗粒体积含量占全部颗粒的10％。D50可以指颗粒累积分布为50％的粒径。D10和D50可采用本领域已知的方法和仪器测定。例如，可以参照GB/T 19077-2016粒度分布激光衍射法，采用激光粒度分析仪(例如英国马尔文Mastersizer 2000E)测定。
磷酸铁锂作为正极活性材料应用于二次电池中，能够使得二次电池具备良好的低温功率性能、动力学性能和快充快放性能。并非意在受限于任何理论或解释，发明人发现，磷酸铁锂的粒径在上述较小的范围内，对二次电池的性能提升更为显著。然而，随着磷酸铁锂粒径的减小，磷酸铁锂颗粒在正极浆料中发生团聚的可能性也有所提升。在本申请的正极组合物中包括防凝聚剂，应用于正极浆料中，即使磷酸铁锂的粒径在上述较小的范围内，也能够有效降低正极浆料产生凝胶现象的风险。由此，本申请的正极组合物应用于二次电池，不仅能够保证二次电池具备良好的低温功率性能、动力学性能和快充快放性能，还能够降低二次电池的制造成本、提高二次电池的产能。
在一些实施方式中，防凝聚剂的数均分子量可为1000～10000，2000～9000，3000～8000，4000～7000，5000～6000。
并非意在受限于任何理论或解释，发明人发现，防凝聚剂的数均分子量在上述合适的范围内，不仅有利于防凝聚剂中的亚磷酸基团与含锂磷酸盐之间生成氢键，还有利于防凝聚剂分子链的相互分散。由此，能够保证连接有含锂磷酸盐的防凝聚剂分子链相互独立、稳定地分散在正极浆料的溶剂中，从而防止正极浆料产生凝胶现象，进而降低二次电池的制造成本、提高二次电池的产能。
在一些实施方式中，防凝聚剂可以包括式1所示的化合物，在式1中，m可选自20～180、30～170、40～160、50～150、60～150、70～150、 80～150的整数，n选自25～150、30～140、40～130、50～120的整数。
式1所示的化合物可通过多种方式获得。在一些实施例中，式1所示的化合物可以自制得到。具体地，式1所示的化合物可以通过以下步骤S1～S3制备。
S1，在反应条件下，使小分子醇类物质与环氧烷类物质聚合，从而得到重复单元中包含醚键的聚合物，可选地，环氧烷类物质包括环氧乙烷。
S2，将上述重复单元中包含醚键的聚合物与胺类高分子反应，从而得到重复单元中包含醚键的胺类聚合物。
S3，将上述重复单元中包含醚键的胺类聚合物与亚磷酸混合，以在反应条件下反应得到式1所示的化合物。
容易理解的，以上步骤作为式1所示化合物制备的一个示例，仅是为了解释本申请，而不是为了限制本申请。
并非意在受限于任何理论或解释，发明人发现，式1所示的化合物中，亚磷酸基团位于端基，有利于与含锂磷酸盐生成氢键。此外，式1所示的化合物中，m、n的值在上述范围内，能够使得分子链的体积以及醚键在分子链中的占比都处于合适的范围。由此，防凝聚剂的分子链之间能够通过电荷作用相互排斥，从而稳定地分散在正极浆料的溶剂中。本申请的防凝聚剂包括式1所示的化合物，能够进一步降低正极浆料产生凝胶的风险，从而提高二次电池的产能。
在一些实施方式中，正极组合物还可以包括碳纳米管(CNT)，具体地可以包括单壁碳纳米管(SWCNT)和/或多壁碳纳米管(MWCNT)。可选地，碳纳米管可以为单壁碳纳米管(SWCNT)。
为了充分发挥含锂磷酸盐的低温功率性能，发明人在解决了正极浆料静置易产生凝胶现象的问题之后，仍进行了深入的研究。
并非意在受限于任何理论或解释，发明人意外地发现，在本申请的正极组合物中包括碳纳米管，能够显著增强正极组合物的导电性能，从而降低正极组合物的阻抗，进而充分发挥含锂磷酸盐的低温功率性能。具体地，如图1所示，包括碳纳米管的正极组合物应用于正极浆料时，防凝聚剂02分子链中的亚磷酸基团021能够“锚固”正极活性材料01表面的含锂磷酸盐分子，并且相邻的被“锚固”的正极活性材料01由于防凝聚剂02分子链之间的排斥作用而稳定地独立存在。而碳纳米管03和防凝聚剂02的分子链具有一定的柔性，在溶剂中分散时，碳纳米管03可以分散、缠绕于防凝聚剂02的分子链上，由此正极组合物的导电性能得到显著的提升。尤其是，由于单壁碳纳米管相较于多壁碳纳米管具有更大的长径比，更容易缠绕在防凝聚剂02的分子链上，正极组合物中包括单壁碳纳米管时，能够进一步提升正极组 合物的导电性能。因此，本申请的正极组合物中包括碳纳米管时，应用于正极浆料中，能够使得制备得到的二次电池不仅具有高产能、低成本的特点，还具有优异的低温功率性能。
在一些实施方式中，正极组合物还可以包括粘结剂和导电剂。可选地，基于正极组合物的总质量，正极活性材料的质量占比可为93wt％～96.9wt％，防凝聚剂的质量占比可为0.1wt％～0.5wt％、0.2wt％～0.5wt％或0.3wt％～0.5wt％，粘结剂的质量占比可为1wt％～2wt％，导电剂的质量占比为2wt％～4.5wt％。
本申请对粘结剂和导电剂的种类不作限定，粘结剂和导电剂可以为本领域常用的粘结剂和导电剂。作为示例，粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种；导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
并非意在受限于任何理论或解释，正极组合物中，正极活性材料、防凝聚剂、粘结剂、导电剂的质量占比在上述范围内，应用于正极浆料，能够有效防止凝胶现象的产生；应用于二次电池，能够使得正极极片具有良好电子传导性能和活性离子传输能力，以及良好的结构稳定性。由此，能够提高二次电池的产能，并保证二次电池具备良好的电化学性能。
在一些实施方式中，正极组合物还包括粘结剂、导电剂和碳纳米管。可选地，基于正极组合物的总质量，正极活性材料的质量占比可为93wt％～96wt％，防凝聚剂的质量占比可为0.1wt％～0.5wt％、0.2wt％～0.5wt％或0.3wt％～0.5wt％，碳纳米管的质量占比可为0.1wt％～1wt％，粘结剂的质量占比可为1wt％～2wt％，导电剂的质量占比可为2wt％～4wt％。
粘结剂和导电剂的示例如上所述，在此不再赘述。
并非意在受限于任何理论或解释，正极组合物中，正极活性材料、防凝聚剂、碳纳米管、粘结剂、导电剂的质量占比在上述范围内，应用于正极浆料，能够有效防止凝胶现象的产生；应用于二次电池，能够使得正极极片具有良好电子传导性能和活性离子传输能力，以及良好的结构稳定性。由此，能够提高二次电池的产能，并保证二次电池具备良好的电化学性能。
在一些实施方式中，正极组合物中，含锂磷酸盐与碳纳米管的质量比为1:0.003～1:0.01，例如可以为1:0.003，1:0.004，1:0.005，1:0.006，1:0.007，1:0.008，1:0.009，1:0.01。
并非意在受限于任何理论或解释，含锂磷酸盐与碳纳米管的质量比在上述范围内，能够有效提升正极组合物的导电性能，从而能够使得应用本申请正极组合物的二次电池具有低直流电阻(DCR)、长循环寿命。
在一些实施方式中，含锂磷酸盐与防凝聚剂的质量比可为1:0.003～1:0.006，例如可以为1:0.003，1:0.004，1:0.005，1:0.006。
并非意在受限于任何理论或解释，含锂磷酸盐与防凝聚剂的质量比在 上述范围内，能够在有效减少正极浆料的凝胶现象的同时，使得正极组合物具有更高的能量密度、更低的成本以及良好的电化学性能，由此，应用于二次电池中，能够保证二次电池具有高产能、低成本和良好的电化学性能。
正极浆料
本申请第二方面提供一种正极浆料，包括溶剂以及本申请的正极组合物。
在一些实施方式中，上述溶剂可以为氮甲基吡咯烷酮(NMP)。
在一些实施方式中，正极浆料的固体组分含量可以为55wt％～65wt％。正极浆料的固体组分含量在合适的范围内，能够便于控制正极极片的涂布重量和膜层厚度，从而兼顾正极极片的能量密度、电解液浸润速率和电子传导能量，进而提高二次电池的电化学性能。
在一些实施方式中，正极浆料的粘度可为7000mPa·s至15000mPa·s。正极浆料具有合适的粘度，有利于在正极集流体的表面形成厚度均一的涂层，从而提高正极极片的优率、提高二次电池的产能。
用于制备正极浆料的方法
本申请还提供一种用于制备本申请的正极浆料的方法，包括：将包括本申请的正极组合物的正极材料与溶剂混合均匀，从而得到正极浆料。
需要说明的是，本申请的方法中，将包括本申请的正极组合物的正极材料与溶剂混合均匀，可以包括将正极组合物中的各组份混合均匀后，再与溶剂混合；也可以包括将正极组合物中的各组份按照一定的顺序与溶剂混合。作为一个示例，可以将正极活性材料、导电剂、粘结剂与溶剂混合均匀后，加入碳纳米管和防凝聚剂，再加入溶剂以调节浆料粘度。
在一些实施方式中，所述溶剂可以为氮甲基吡咯烷酮(NMP)。
在一些实施方式中，所述正极浆料的固体组分含量可为55wt％～65wt％。正极浆料的固体组分含量在合适的范围内，能够便于控制正极极片的涂布重量和膜层厚度，从而兼顾正极极片的能量密度、电解液浸润速率和电子传导能量，进而提高二次电池的电化学性能。
在一些实施方式中，正极浆料的粘度可以为7000mPa·s至15000mPa·s。正极浆料具有合适的粘度，有利于在正极集流体的表面形成厚度均一的涂层，从而提高正极极片的优率、提高二次电池的产能。
正极极片
本申请第三方面提供一种正极极片，包括正极集流体以及位于所述正极集流体至少一个表面上的正极膜层，其中，所述正极膜层包括根据本申请的正极组合物、或所述正极膜层为本申请的正极浆料干燥后形成的层。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在一些实施方式中，所述正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材 料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，可以通过以下方式制备正极极片：将本申请的正极组合物和可选的其他的组分分散于溶剂(例如NMP)中，形成正极浆料，或者直接使用本申请的正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片。
需要说明的是，本申请的正极极片中，正极膜层所含物质可以在电池制备过程中，或者从制备好的二次电池中取样测试，测试方法可以为本领域公知的方法，例如通过扫描电子显微镜进行测试。
二次电池
另外，以下适当参照附图对本申请的二次电池、电池模块、电池包和用电装置进行说明。
本申请的一个实施方式中，提供一种二次电池。
通常情况下，二次电池包括正极极片、负极极片、电解质和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。
[正极极片]
正极极片选自根据本申请第三方面的正极极片。
[负极极片]
负极极片包括负极集流体以及设置在负极集流体至少一个表面上的负极膜层，所述负极膜层包括负极活性材料。
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极膜层设置在负极集流体相对的两个表面中的任意一者或两者上。
在一些实施方式中，所述负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。所述硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。所述锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少 一种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极活性材料的传统材料。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
在一些实施方式中，负极膜层还可选地包括粘结剂。所述粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。
在一些实施方式中，负极膜层还可选地包括导电剂。导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，负极膜层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。
在一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，即可得到负极极片。
[电解质]
电解质在正极极片和负极极片之间起到传导离子的作用。本申请对电解质的种类没有具体的限制，可根据需求进行选择。例如，电解质可以是液态的、凝胶态的或全固态的。
在一些实施方式中，所述电解质采用电解液。所述电解液包括电解质盐和溶剂。
在一些实施方式中，电解质盐可选自六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟磷酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二氟二草酸磷酸锂及四氟草酸磷酸锂中的至少一种。
在一些实施方式中，溶剂可选自碳酸亚乙酯、碳酸亚丙酯、碳酸甲乙酯、碳酸二乙酯、碳酸二甲酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸亚丁酯、氟代碳酸亚乙酯、甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯、1,4-丁内酯、环丁砜、二甲砜、甲乙砜及二乙砜中的至少一种。
在一些实施方式中，所述电解液还可选地包括添加剂。例如添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
[隔离膜]
在一些实施方式中，二次电池中还包括隔离膜。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施方式中，二次电池可包括外包装。该外包装可用于封装上述电极组件及电解质。
在一些实施方式中，二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图2是作为一个示例的方形结构的二次电池5。
在一些实施方式中，参照图3，外包装可包括壳体51和顶盖组件53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，顶盖组件53能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔内。电解液浸润于电极组件52中。二次电池5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，二次电池可以组装成电池模块，电池模块所含二次电池的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
图4是作为一个示例的电池模块4。参照图4，在电池模块4中，多个二次电池5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个二次电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个二次电池5容纳于该容纳空间。
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以为一个或多个，具体数量本领域技术人员可根据电池包的应用和容量进行选择。
图5和图6是作为一个示例的电池包1。参照图5和图6，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
另外，本申请还提供一种用电装置，所述用电装置包括本申请提供的二次电池、电池模块、或电池包中的至少一种。所述二次电池、电池模 块、或电池包可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于此。
作为所述用电装置，可以根据其使用需求来选择二次电池、电池模块或电池包。
图7是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的用电装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用二次电池作为电源。
实施例
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
实施例1～17
正极浆料的制备
将磷酸铁锂、粘结剂PVDF、导电剂Super P按照一定的质量比加入到搅拌罐中，以25rpm的公转速度、800rpm的自转速度搅拌15分钟，得到干混物。
将干混物与溶剂NMP混合均匀，得到固体组份含量为60wt％的初始正极浆料。
向初始正极浆料中加入防凝聚剂和可选的碳纳米管(CNT)，搅拌均匀后再调节粘度为7000mPa·s～15000mPa·s，即得到正极浆料。
各实施例所用的防凝聚剂选自如式1所示的化合物。各实施例中，磷酸铁锂的粒径D10、磷酸铁锂在正极浆料的固体组份含量中的占比w1、防凝聚剂的数均分子量Mn、防凝聚剂在正极浆料的固体组份含量中的占比w2、防凝聚剂与磷酸铁锂的质量比CNT的种类、CNT在正极浆料的固体组份含量中的占比w3、CNT与磷酸铁锂的质量比如表1所示。
对比例1～3
基于实施例1～17的正极浆料的制备过程，根据表1中所示正极浆料的制备参数，制备对比例1～3的正极浆料。
表1：实施例1～17与对比例1～3的制备参数
在25℃下，将上述实施例1～17、对比例1～3的正极浆料静置48小时后，进行以下测试，测试结果如下表2所示。
(1)150目筛网透过程度测试
使用150目的筛网对正极浆料进行过筛，观察正极浆料在150目筛网中的透过程度。
(2)正极浆料粘度测试
使用旋转粘度计，根据样品粘度选择转子，使用粘度计升降架，使粘度计缓慢下降，转子浸没在浆料中，直至转子上的标记与液面持平，测试温度：25℃，转速：12rpm，按测量键开始测量，5min后数据保持稳定后，读取粘度值即可。
表2：实施例1～17与对比例1～3的正极浆料的测试参数
另外，将上述实施例1～17和对比例1～3中得到的正极浆料分别如下所示制备成二次电池，进行性能测试。测试结果如下表3所示。
(1)二次电池的制备
正极极片的制备
将制备得到的正极浆料均匀涂覆于正极集流体上，之后经过烘干、冷压、分切，得到正极极片。
负极极片的制备
将活性物质人造石墨、导电剂碳黑、粘结剂丁苯橡胶(SBR)、增稠剂羟甲基纤维素钠(CMC-Na)按照重量比为96.2：0.8：0.8：1.2溶于溶剂去离子水中，混合均匀后制备成负极浆料；将负极浆料一次或多次均匀涂覆在负极集流体铜箔上，经过烘干、冷压、分切得到负极极片。
电解液的制备
在氩气气氛手套箱中(H2O<0.1ppm，O2<0.1ppm)，将有机溶剂碳酸乙烯酯(EC)/碳酸甲乙酯(EMC)按照体积比3/7混合均匀，加入12.5％LiPF6锂盐溶解于有机溶剂中，搅拌均匀，即得。
隔离膜
以聚丙烯膜作为隔离膜。
二次电池的制备
将正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正、负极片之间起到隔离的作用，然后卷绕得到电极组件，给电极组件焊接极耳， 并将电极组件装入铝壳中，于100℃下烘烤除水，随即注入电解液并封口，得到不带电的电池。不带电的电池再依次经过静置、热冷压、化成、整形、容量测试等工序，获得二次电池。
(2)二次电池的低温功率测试
将二次电池置于温箱中，在25℃下，以1C的倍率放电至50％SOC，然后调节温箱温度至-20℃，搁置2h后，以3C的倍率放电120s，搁置30min，取放电120s过程中的最低电压为端电压。
此外，分别以上述放电120s过程中的时间和电压值为横坐标轴和纵坐标轴，记录每一时刻对应的电压值，得到二次电池的低温功率测试图。实施例1和对比例1的二次电池的低温功率测试图分别如图8、图9所示。
表3：实施例1～17与对比例1～3的性能测试结果
由上述表1至表3可知，在正极浆料中包括防凝聚剂，能够有效降低正极浆料的凝胶程度。具体地，由实施例1～5可知，随着磷酸铁锂的粒径D10的减小，制备得到的二次电池的低温功率性能越好，但相应地，正极浆料的凝胶程度也越大。在正极浆料中包括防凝聚剂，即使磷酸铁锂的粒径D10为100nm，正极浆料静置48h后仍然能够具有较低的粘度，由此能够在减轻正极浆料凝胶程度的同时，充分发挥磷酸铁锂应用于二次电池的低温功率性能。由实施例3、7～9、10～12可知，防凝聚剂的数均分子量在本申请的范围内，均能有效降低正极浆料的凝胶程度，且随着防凝聚剂的添加量增多，正极浆料的凝胶程度降低。由实施例3、13～17可知，在正浆料中包括碳纳米管，尤其是包括单壁碳纳米管，能够显著提升二次电池的低温功率性能。
而相对于此，对比例1～3中的正极浆料不包括防凝聚剂，静置48h后，正极浆料的粘度显著提升，由此，二次电池的产能和制造成本相较于实施例1～17均不够理想。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。

Claims (16)

  1. 一种用于锂电池正极的正极组合物，包括正极活性材料和防凝聚剂，其中，所述正极活性材料包括含锂磷酸盐，所述防凝聚剂包括分子链中包含亚磷酸基团和醚键的聚合物。
  2. 根据权利要求1所述的正极组合物，其中，所述含锂磷酸盐包括磷酸铁锂，可选地，所述磷酸铁锂的粒径D10为100nm～800nm，更可选地，所述磷酸铁锂的粒径D10为200nm～300nm，D50为400nm～600nm。
  3. 根据权利要求1或2所述的正极组合物，其中，所述防凝聚剂的数均分子量为1000～10000、可选为3000～8000。
  4. 根据权利要求1-3任一项所述的正极组合物，其中，所述防凝聚剂包括式1所示的化合物，
    在式1中，m选自20～180、可选为60～150的整数，n选自25～150、可选为50～120的整数。
  5. 根据权利要求1-4任一项所述的正极组合物，其中，所述正极组合物还包括碳纳米管，可选地，所述碳纳米管为单壁碳纳米管。
  6. 根据权利要求1-4任一项所述的正极组合物，其中，所述正极组合物还包括粘结剂和导电剂，
    可选地，基于所述正极组合物的总质量，所述正极活性材料的质量占比为93wt％～96.9wt％，所述防凝聚剂的质量占比为0.1wt％～0.5wt％、可选为0.3wt％～0.5wt％，所述粘结剂的质量占比为1wt％～2wt％，所述导电剂的质量占比为2wt％～4.5wt％。
  7. 根据权利要求5所述的正极组合物，其中，所述正极组合物还包括粘结剂和导电剂，
    可选地，基于所述正极组合物的总质量，所述正极活性材料的质量占比为93wt％～96wt％，所述防凝聚剂的质量占比为0.1wt％～0.5wt％、可选为0.3wt％～0.5wt％，所述碳纳米管的质量占比为0.1wt％～1wt％，所述粘结剂的质量占比为1wt％～2wt％，所述导电剂的质量占比为2wt％～4wt％。
  8. 根据权利要求5或7所述的正极组合物，其中，所述正极组合物中，所述含锂磷酸盐与所述碳纳米管的质量比为1:0.003～1:0.01。
  9. 根据权利要求1-8任一项所述的正极组合物，其中，所述正极组合物中，所述含锂磷酸盐与所述防凝聚剂的质量比为1:0.003～1:0.006。
  10. 一种正极浆料，包括溶剂以及根据权利要求1-9任一项所述的正极组合物。
  11. 根据权利要求10所述的正极浆料，其中，所述正极浆料满足如下至 少一者：
    (1)所述溶剂为氮甲基吡咯烷酮；
    (2)所述正极浆料的固体组分含量为55wt％～65wt％；
    (3)所述正极浆料的粘度为7000mPa·s～15000mPa·s。
  12. 一种正极极片，包括正极集流体以及位于所述正极集流体至少一个表面上的正极膜层，其中，所述正极膜层包括根据权利要求1-9中任一项所述的正极组合物、或所述正极膜层为根据权利要求10或11所述的正极浆料干燥后形成的层。
  13. 一种二次电池，包括权利要求12所述的正极极片。
  14. 一种电池模块，包括权利要求13所述的二次电池。
  15. 一种电池包，包括权利要求14所述的电池模块。
  16. 一种用电装置，包括选自权利要求13所述的二次电池、权利要求14所述的电池模块或权利要求15所述的电池包中的至少一种。
PCT/CN2023/076427 2022-03-22 2023-02-16 正极组合物、正极浆料、正极极片、二次电池、电池模块、电池包和用电装置 WO2023179256A1 (zh)

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