CN116825976A - Positive electrode composition, positive electrode slurry, positive electrode sheet, secondary battery, battery module, battery pack, and electricity device - Google Patents
Positive electrode composition, positive electrode slurry, positive electrode sheet, secondary battery, battery module, battery pack, and electricity device Download PDFInfo
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- CN116825976A CN116825976A CN202210282381.1A CN202210282381A CN116825976A CN 116825976 A CN116825976 A CN 116825976A CN 202210282381 A CN202210282381 A CN 202210282381A CN 116825976 A CN116825976 A CN 116825976A
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- positive electrode
- secondary battery
- electrode composition
- battery
- mass ratio
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Classifications
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The application provides a positive electrode composition, positive electrode slurry, a positive electrode plate, a secondary battery, a battery module, a battery pack and an electric device. The positive electrode composition comprises a positive electrode active material and an anti-agglomerating agent, wherein the positive electrode active material comprises lithium-containing phosphate, and the anti-agglomerating agent comprises a polymer containing phosphite groups and ether bonds in a molecular chain.
Description
Technical Field
The application relates to the technical field of secondary batteries, in particular to a positive electrode composition, positive electrode slurry, a positive electrode plate, a secondary battery, a battery module, a battery pack and an electric device.
Background
In recent years, as the application range of secondary batteries is becoming wider, secondary batteries are widely used in energy storage power systems such as hydraulic power, thermal power, wind power and solar power stations, and in various fields such as electric tools, vehicles, military equipment, aerospace and the like.
With the improvement of the market status of secondary batteries, not only are secondary batteries expected to have higher energy density and better cycle performance, but also secondary batteries are expected to have lower manufacturing costs and higher productivity.
However, at present, in the process of the industrial production of the secondary battery, some material loss is inevitably generated, thereby resulting in an increase in the manufacturing cost of the secondary battery and a decrease in the productivity of the secondary battery.
Disclosure of Invention
The present application has been made in view of the above problems, and an object of the present application is to provide a positive electrode composition that can provide a secondary battery with both low cost and good electrochemical performance.
In order to achieve the above object, the present application provides a positive electrode composition, a positive electrode slurry, a positive electrode sheet, a secondary battery, a battery module, a battery pack, and an electric device.
A first aspect of the present application provides a positive electrode composition for a positive electrode of a lithium battery, comprising a positive electrode active material and an anti-agglomerating agent, wherein the positive electrode active material comprises a lithium-containing phosphate, and the anti-agglomerating agent comprises a polymer comprising a phosphorous acid group and an ether linkage in a molecular chain.
The positive electrode composition of the application comprises lithium-containing phosphate and the anti-agglomerating agent, wherein the phosphorous acid group in the anti-agglomerating agent can interact with the phosphate radical in the lithium-containing phosphate through hydrogen bonds, so that the lithium-containing phosphate is anchored on the molecular chain of the anti-agglomerating agent. Other parts of the molecular chain of the anti-agglomerating agent can generate strong charge action with other molecular chains, so that the molecular chains of the anti-agglomerating agent are mutually repelled, and the molecular chains of the anti-agglomerating agent connected with lithium-containing phosphate can be mutually independent and stably dispersed in the solvent of the positive electrode slurry. Therefore, the positive electrode composition is applied to the positive electrode slurry of the secondary battery, can effectively reduce the aggregation of the positive electrode active material and relieve the gel phenomenon of the positive electrode slurry, and can reduce the use amount of the solvent, the back stirring process and improve the solid content of the positive electrode slurry. Thus, the positive electrode composition of the present application is applied to a secondary battery, and can reduce the manufacturing cost of the secondary battery, improve the productivity of the secondary battery, and maintain good electrochemical performance of the secondary battery.
In any embodiment of the first aspect of the present application, the lithium-containing phosphate comprises lithium iron phosphate, optionally having a particle size D 10 From 100nm to 800nm, more optionallyParticle diameter D of lithium iron phosphate 10 200nm to 300nm, D 50 400nm to 600nm. The positive electrode composition of the application comprises an anti-agglomerating agent, and is applied to positive electrode slurry, and even if the particle size of lithium iron phosphate is in the smaller range, the risk of gel phenomenon generated by the positive electrode slurry can be effectively reduced. Therefore, the positive electrode composition is applied to the secondary battery, so that the secondary battery has good low-temperature power performance, good dynamic performance and good quick charge and quick discharge performance, the manufacturing cost of the secondary battery can be reduced, and the productivity of the secondary battery can be improved.
In any embodiment of the first aspect of the application, the anti-agglomerating agent has a number average molecular weight of 1000 to 10000, optionally 3000 to 8000. The number average molecular weight of the anti-agglomerating agent is within the proper range, so that the molecular chains of the anti-agglomerating agent connected with the lithium-containing phosphate can be ensured to be mutually independent and stably dispersed in the solvent of the positive electrode slurry, thereby preventing the gel phenomenon of the positive electrode slurry, further reducing the manufacturing cost of the secondary battery and improving the productivity of the secondary battery.
In any embodiment of the first aspect of the application, the anti-agglomerating agent comprises a compound of formula 1,
in formula 1, m is an integer from 20 to 180, optionally from 60 to 150, and n is an integer from 25 to 150, optionally from 50 to 120. In the compound represented by formula 1, the phosphorous acid group is located at the terminal group, and the volume of the molecular chain and the ratio of the ether bond in the molecular chain are in a suitable range, whereby the molecular chains of the anti-agglomerating agent can repel each other by the charge action, thereby being stably dispersed in the solvent of the positive electrode slurry. The anti-agglomerating agent of the present application includes the compound shown in formula 1, and can further reduce the risk of gel generation of the positive electrode slurry, thereby improving the productivity of the secondary battery.
In any embodiment of the first aspect of the application, the positive electrode composition further comprises carbon nanotubes. Optionally, the carbon nanotubes are single-walled carbon nanotubes. When the carbon nano tube is included in the positive electrode composition, the carbon nano tube is applied to positive electrode slurry, so that the prepared secondary battery has the characteristics of high productivity and low cost, and also has excellent low-temperature power performance.
In any embodiment of the first aspect of the application, the positive electrode composition further comprises a binder and a conductive agent. Alternatively, the positive electrode active material is 93wt% to 96.9wt%, the anti-agglomerating agent is 0.1wt% to 0.5wt%, optionally 0.3wt% to 0.5wt%, the binder is 1wt% to 2wt%, and the conductive agent is 2wt% to 4.5wt%, based on the total mass of the positive electrode composition. The mass ratio of the positive electrode active material, the anti-agglomerating agent, the binder and the conductive agent is in the range, and the anti-agglomerating agent is applied to positive electrode slurry, so that the gel phenomenon can be effectively prevented; the positive electrode plate is applied to a secondary battery, and can have good electron conduction performance, active ion transmission capability and good structural stability.
In any embodiment of the first aspect of the present application, the positive electrode composition further comprises a binder, a conductive agent, and carbon nanotubes. Alternatively, the positive electrode active material is 93wt% to 96wt%, the anti-agglomerating agent is 0.1wt% to 0.5wt%, optionally 0.3wt% to 0.5wt%, the carbon nanotube is 0.1wt% to 1wt%, the binder is 1wt% to 2wt%, and the conductive agent is 2wt% to 4wt%, based on the total mass of the positive electrode composition. In the positive electrode composition, the mass ratio of the positive electrode active material, the anti-agglomerating agent, the carbon nano tube, the binder and the conductive agent is in the range, and the positive electrode composition can be applied to positive electrode slurry to effectively prevent the generation of gel phenomenon; the positive electrode plate is applied to a secondary battery, and can further improve the electron conduction performance, the active ion transmission capacity and the structural stability of the positive electrode plate.
In any embodiment of the first aspect of the present application, the mass ratio of the lithium-containing phosphate to the carbon nanotubes in the positive electrode composition is 1:0.003 to 1:0.01. The mass ratio of the lithium-containing phosphate to the carbon nanotubes is in the above range, and the conductivity of the positive electrode composition can be effectively improved, so that the secondary battery using the positive electrode composition has low Direct Current Resistance (DCR) and long cycle life.
In any embodiment of the first aspect of the present application, the mass ratio of the lithium-containing phosphate to the anti-agglomerating agent in the positive electrode composition is 1:0.003 to 1:0.006. The mass ratio of the lithium-containing phosphate to the anti-agglomerating agent is in the range, so that the gel phenomenon of the positive electrode slurry can be effectively reduced, and the positive electrode composition has higher energy density, lower cost and good electrochemical performance, and therefore, the lithium-containing phosphate and the anti-agglomerating agent can be applied to a secondary battery, and the secondary battery can be ensured to have high productivity, low cost and good electrochemical performance.
A second aspect of the present application provides a positive electrode slurry comprising a solvent and a positive electrode composition according to the first aspect of the present application.
The positive electrode slurry of the application comprises the positive electrode composition of the application, so that the positive electrode slurry of the application is not easy to generate gel phenomenon due to agglomeration of positive electrode active materials, thereby reducing the use amount of solvent and the back stirring process and improving the solid content of the positive electrode slurry. Therefore, the positive electrode slurry is applied to the secondary battery, can reduce the manufacturing cost of the secondary battery, improve the productivity of the secondary battery and ensure that the secondary battery maintains good electrochemical performance.
In any embodiment of the second aspect of the present application, the positive electrode slurry satisfies at least one of the following (1) to (3).
(1) The solvent is nitrogen methyl pyrrolidone.
(2) The solid component content of the positive electrode slurry is 55-65wt%. The solid component content of the positive electrode slurry is in a proper range, so that the coating weight and the film thickness of the positive electrode plate can be conveniently controlled, and the energy density, the electrolyte infiltration rate and the electron conduction energy of the positive electrode plate are taken into account, and the electrochemical performance of the secondary battery is further improved.
(3) The viscosity of the positive electrode slurry is 7000 mPas to 15000 mPas. The positive electrode slurry has proper viscosity, and is favorable for forming a coating with uniform thickness on the surface of the positive electrode current collector, so that the rate of the positive electrode plate is improved, and the productivity of the secondary battery is improved.
The third aspect of the application provides a positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer positioned on at least one surface of the positive electrode current collector. Wherein the positive electrode film layer comprises the positive electrode composition according to the first aspect of the present application, or the positive electrode film layer is a layer formed by drying the positive electrode slurry according to the second aspect of the present application.
In the positive electrode sheet, the positive electrode film layer comprises the positive electrode composition or is formed by drying the positive electrode slurry, so that the positive electrode sheet has low preparation cost, high productivity and good electrochemical performance. Therefore, the positive electrode plate is applied to the secondary battery, can reduce the manufacturing cost of the secondary battery, improve the productivity of the secondary battery and ensure that the secondary battery maintains good electrochemical performance.
A fourth aspect of the application provides a secondary battery comprising the positive electrode tab of the third aspect of the application.
The secondary battery of the present application includes the positive electrode tab of the present application, thereby being capable of having low manufacturing cost, high productivity, and good electrochemical performance.
A fifth aspect of the present application provides a battery module comprising the secondary battery of the fourth aspect of the present application.
A sixth aspect of the application provides a battery pack comprising the battery module of the fifth aspect of the application.
A seventh aspect of the present application provides an electric device comprising 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.
The battery module, the battery pack, and the power consumption device of the present application include the secondary battery provided by the present application, and thus have at least the same advantages as the secondary battery of the present application.
Drawings
Fig. 1 is a schematic view showing a state in which a positive electrode composition exists in a positive electrode slurry in an embodiment of the positive electrode composition of the present application.
Fig. 2 is a schematic view of an embodiment of the 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 view of an embodiment of a battery module of the present application.
Fig. 5 is a schematic view of an embodiment of a battery pack of the present application.
Fig. 6 is an exploded view of the embodiment of the battery pack of the present application shown in fig. 5.
Fig. 7 is a schematic view of an electric device for use as a power source according to an embodiment of the secondary battery of the present application.
Fig. 8 is a low temperature power test chart of the secondary battery of embodiment 1 of the present application.
Fig. 9 is a low temperature power test chart of the secondary battery of comparative example 1 of the present application.
Reference numerals illustrate:
01 positive electrode active material; 02 anti-agglomerating agent; 03 carbon nanotubes; 021 phosphite group; 1, a battery pack; 2, upper box body; 3, lower box body; 4, a battery module; 5 a secondary battery; 51 a housing; 52 electrode assembly; 53 top cap assembly.
Detailed Description
Hereinafter, embodiments of the positive electrode composition, positive electrode slurry, positive electrode sheet, secondary battery, battery module, battery pack, and electric device of the present application are specifically disclosed with reference to the accompanying drawings as appropriate. However, unnecessary detailed description may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of the actual same structure may be omitted. This is to avoid that the following description becomes unnecessarily lengthy, facilitating the understanding of those skilled in the art. Furthermore, the drawings and the following description are provided for a full understanding of the present application by those skilled in the art, and are not intended to limit the subject matter recited in the claims.
The "range" disclosed herein is defined in terms of lower and upper limits, with the given range being defined by the selection of a lower and an upper limit, the selected lower and upper limits defining the boundaries of the particular range. Ranges that are defined in this way can be inclusive or exclusive of the endpoints, and any combination can be made, i.e., any lower limit can 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, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3,4 and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise indicated, the numerical range "a-b" represents a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed throughout, and "0-5" is simply a shorthand representation of a combination of these values. When a certain parameter is expressed as an integer of 2 or more, it is disclosed that the parameter is, for example, an integer of 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12 or the like.
All embodiments of the application and alternative embodiments may be combined with each other to form new solutions, unless otherwise specified.
All technical features and optional technical features of the application may be combined with each other to form new technical solutions, unless specified otherwise.
All the steps of the present application may be performed sequentially or randomly, preferably sequentially, unless otherwise specified. For example, the method comprises steps (a) and (b), meaning that the method may comprise steps (a) and (b) performed sequentially, or may comprise steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), may include steps (a), (c) and (b), may include steps (c), (a) and (b), and the like.
The terms "comprising" and "including" as used herein mean open ended or closed ended, unless otherwise noted. For example, the terms "comprising" and "comprises" may mean that other components not listed may be included or included, or that only listed components may be included or included.
The term "or" is inclusive in this application, unless otherwise specified. For example, the phrase "a or B" means "a, B, or both a and B. More specifically, either of the following conditions satisfies the condition "a or B": a is true (or present) and B is false (or absent); a is false (or absent) and B is true (or present); or both A and B are true (or present).
With the development of secondary batteries, it is desirable that the secondary batteries have lower manufacturing costs and higher productivity while having good electrochemical performance. From the viewpoint of manufacturing the secondary battery, each step has an important influence on the manufacturing cost and productivity of the secondary battery.
The inventor finds that in the existing manufacturing process of the positive electrode plate, serious raw material loss exists, and the production efficiency is low. In particular, the inventors found that, in the industrial production of secondary batteries, after the preparation of the positive electrode slurry is completed, it is generally required to be left for a while and then sent through a conveying pipe for coating to form a positive electrode film layer. Because the particle size of the positive electrode material is smaller, a large amount of nanometer micro powder exists in the prepared positive electrode slurry, and the nanometer micro powder is easy to agglomerate to generate gel.
At present, in order to alleviate the gelation phenomenon of the positive electrode slurry, the positive electrode slurry is usually placed in a stirring tank for continuous slow stirring, and after the gelation phenomenon occurs, a solvent is added for back stirring and viscosity adjustment. However, the positive electrode slurry cannot be stirred back in the transfer pipe, and a gel phenomenon is likely to occur in the transfer pipe. In addition, the back-stirring and viscosity-adjusting increase the amount of the solvent, thereby increasing the manufacturing cost of the secondary battery.
In view of this, the inventors have intensively studied to provide a positive electrode composition, a positive electrode slurry, a positive electrode sheet, a secondary battery, a battery module, a battery pack, and an electric device.
Positive electrode composition
The first aspect of the present application provides a positive electrode composition, which can be used for a lithium battery. The positive electrode composition includes a positive electrode active material and an anti-coagulant. Wherein the positive electrode active material comprises lithium-containing phosphate, and the anti-agglomerating agent comprises a polymer containing a phosphorous acid group and an ether bond in a molecular chain.
In the molecular chain of the anti-agglomerating agent, one or more phosphorous acid groups can be adopted, and the phosphorous acid groups can be end groups or groups in branched chains; the ether bond may be one or more, and the ether bond may be located at the chain end, in a segment of the main chain, or in a branch chain. Alternatively, the ether linkage may be contained in a repeating unit of the molecular chain.
Although the mechanism is not yet clear, the inventors have unexpectedly found that: the positive electrode composition provided by the application comprises lithium-containing phosphate and the anti-agglomerating agent, and can be applied to positive electrode slurry to effectively prevent the positive electrode slurry from generating gel phenomenon in a standing process and a conveying pipeline.
In particular, without intending to be limited by any theory or explanation, the inventors found that in the anti-agglomerating agent of the present application, the phosphorous acid groups may interact with the phosphate groups in the lithium-containing phosphate through hydrogen bonding, thereby "anchoring" the lithium-containing phosphate to the molecular chain of the anti-agglomerating agent. Other parts of the molecular chain of the anti-agglomerating agent, especially ether bonds, can generate strong charge action with other molecular chains, so that the molecular chains of the anti-agglomerating agent are mutually repelled, and the molecular chains of the anti-agglomerating agent connected with lithium-containing phosphate can be mutually independent and stably dispersed in a solvent of the positive electrode slurry, thereby playing a role in preventing the gel phenomenon of the positive electrode slurry. In some embodiments, the positive electrode composition of the present application is applied to a positive electrode slurry, and the resulting positive electrode slurry does not generate a gel phenomenon even when left to stand for 48 hours. In addition, the anti-agglomerating agent is applied to the positive electrode slurry, the electrochemical performance of the prepared secondary battery is hardly affected, and the secondary battery can keep good electrochemical performance.
The positive electrode composition provided by the application comprises lithium-containing phosphate and an anti-agglomerating agent, is applied to positive electrode slurry of a secondary battery, and can effectively reduce agglomeration of positive electrode active materials and relieve gel phenomenon of the positive electrode slurry, so that the consumption of solvents and back stirring procedures can be reduced, and the solid content of the positive electrode slurry can be improved. Thus, the positive electrode composition of the present application is applied to a secondary battery, and can reduce the manufacturing cost of the secondary battery, improve the productivity of the secondary battery, and maintain good electrochemical performance of the secondary battery.
In some embodiments, the lithium-containing phosphate may include lithium iron phosphate. Alternatively, particle size D of lithium iron phosphate 10 Can be 100nm to 800nm,100nm to 700nm,100nm to 600nm, 100nm to 500nm,100nm to 400nm,100nm to 300nm,100nm to 200nm, 200nm to 800nm,200nm to 700nm,200nm to 600nm,200nm to 500nm,200nm to 400nm,200nm to 300nm,300nm to 800nm,300nm to 600nm,300nm to 500nm,300nm to 400nm,400nm to 800nm, 400nm to 700nm,400nm to 600nm,400nm to 500nm,500nm to 800nm, 500nm to 700nm, 600nm to 800nm, or 700nm to 800nm. More optionally, the particle diameter D of the lithium iron phosphate 10 Can be 200nm to 300nm, D 50 Can be 400nm to 600nm,450nm to 600nm,500nm to 600nm, 400nm to 550nm,450nm to 550nm,500nm to 550nm,400nm to 500nm, 450nm to 500nm and 400nm to 450nm.
In the application, the particle diameter D of the lithium iron phosphate 10 And D 50 Has a meaning known in the art, wherein D 10 It may be referred to a particle size having a cumulative particle distribution of 10%, i.e., a particle volume content of less than this particle size value is 10% of the total particles. D (D) 50 May refer to a particle size with a cumulative distribution of 50% of the particles. D (D) 10 And D 50 The determination may be performed using methods and instruments known in the art. For example, reference may be made to GB/T19077-2016 particle size distribution laser diffraction, using a laser particle size analyzer (e.g.Mastersizer 2000E, UK).
The lithium iron phosphate serving as the positive electrode active material is applied to the secondary battery, so that the secondary battery has good low-temperature power performance, good dynamic performance and good fast charge and fast discharge performance. Without intending to be limited by any theory or explanation, the inventors found that the particle size of the lithium iron phosphate is within the above-described small range, and the improvement in the performance of the secondary battery is more remarkable. However, as the particle size of the lithium iron phosphate decreases, the probability of agglomeration of the lithium iron phosphate particles in the positive electrode slurry increases. The inclusion of the anti-agglomerating agent in the positive electrode composition of the present application is applied to the positive electrode slurry, and even if the particle size of the lithium iron phosphate is within the above-described small range, the risk of the positive electrode slurry developing a gel phenomenon can be effectively reduced. Therefore, the positive electrode composition is applied to the secondary battery, so that the secondary battery has good low-temperature power performance, good dynamic performance and good quick charge and quick discharge performance, the manufacturing cost of the secondary battery can be reduced, and the productivity of the secondary battery can be improved.
In some embodiments, the number average molecular weight of the anti-agglomerating agent may be 1000 to 10000, 2000 to 9000, 3000 to 8000, 4000 to 7000, 5000 to 6000.
Without intending to be limited by any theory or explanation, the inventors found that the number average molecular weight of the anti-coagulant is within the above-described suitable range, not only facilitating the formation of hydrogen bonds between the phosphorous acid groups in the anti-coagulant and the lithium-containing phosphate, but also facilitating the mutual dispersion of the molecular chains of the anti-coagulant. Therefore, the molecular chains of the anti-agglomerating agent connected with the lithium-containing phosphate can be ensured to be mutually independent and stably dispersed in the solvent of the positive electrode slurry, so that the gel phenomenon of the positive electrode slurry is prevented, the manufacturing cost of the secondary battery is further reduced, and the productivity of the secondary battery is improved.
In some embodiments, the anti-agglomerating agent may include a compound represented by formula 1, in formula 1, m may be selected from integers of 20 to 180, 30 to 170, 40 to 160, 50 to 150, 60 to 150, 70 to 150, 80 to 150, and n is selected from integers of 25 to 150, 30 to 140, 40 to 130, 50 to 120.
The compound represented by formula 1 can be obtained in various ways. In some embodiments, the compound of formula 1 may be self-prepared. Specifically, the compound represented by formula 1 can be prepared by the following steps:
S1, polymerizing a micromolecular alcohol substance and an alkylene oxide substance under a reaction condition to obtain a polymer containing ether bonds in a repeating unit, wherein the alkylene oxide substance comprises ethylene oxide optionally;
s2, reacting the polymer containing ether bonds in the repeating units with an amine polymer to obtain an amine polymer containing ether bonds in the repeating units;
s3, mixing amine polymers containing ether bonds in the repeating units with phosphorous acid to react under the reaction condition to obtain the compound shown in the formula 1.
It will be readily appreciated that the above procedure is provided as an example of the preparation of the compounds of formula 1, and is merely to illustrate the application and not to limit it.
Without intending to be limited by any theory or explanation, the inventors found that in the compounds of formula 1, the phosphorous acid group is located at a terminal group, facilitating hydrogen bonding with lithium-containing phosphates. In the compound represented by formula 1, the values of m and n are within the above ranges, and the volume of the molecular chains and the ratio of the ether bond to the molecular chains can be within the appropriate ranges, whereby the molecular chains of the anti-coagulant can be mutually repelled by the charge action and stably dispersed in the solvent of the positive electrode slurry. The anti-agglomerating agent of the present application includes the compound shown in formula 1, and can further reduce the risk of gel generation of the positive electrode slurry, thereby improving the productivity of the secondary battery.
In some embodiments, the positive electrode composition may further include Carbon Nanotubes (CNTs), in particular may include single-walled carbon nanotubes (SWCNTs) and/or multi-walled carbon nanotubes (MWCNTs). Alternatively, the carbon nanotubes may be single-walled carbon nanotubes (SWCNTs).
In order to fully develop the low-temperature power performance of lithium-containing phosphates, the inventors have conducted intensive studies after solving the problem that the positive electrode slurry is liable to gel phenomenon when left to stand.
Without intending to be limited by any theory or explanation, the inventors surprisingly found that including carbon nanotubes in the positive electrode composition of the present application can significantly enhance the conductive properties of the positive electrode composition, thereby reducing the impedance of the positive electrode composition and thereby fully exploiting the low temperature power properties of lithium-containing phosphates. Specifically, as shown in fig. 1, when the positive electrode composition including carbon nanotubes is applied to a positive electrode slurry, phosphorous acid groups 021 in the molecular chain of the anti-agglomerating agent 02 can anchor lithium-containing phosphate molecules on the surface of the positive electrode active material 01, and adjacent positive electrode active materials 01 which are anchored are stably independent due to repulsive interaction between the molecular chains of the anti-agglomerating agent 02, and the molecular chains of the carbon nanotubes 03 and the anti-agglomerating agent 02 have certain flexibility, and when dispersed in a solvent, the carbon nanotubes 03 can be dispersed and wound on the molecular chains of the anti-agglomerating agent 02, so that the conductivity of the positive electrode composition is remarkably improved. In particular, since the single-walled carbon nanotubes have a larger aspect ratio than that of the multi-walled carbon nanotubes, they are more easily entangled in the molecular chains of the anti-agglomerating agent 02, and when the single-walled carbon nanotubes are included in the positive electrode composition, the conductivity of the positive electrode composition can be further improved. Therefore, when the positive electrode composition provided by the application comprises the carbon nano tube, the carbon nano tube is applied to the positive electrode slurry, so that the prepared secondary battery has the characteristics of high productivity and low cost, and also has excellent low-temperature power performance.
In some embodiments, the positive electrode composition may further include a binder and a conductive agent. Alternatively, the positive electrode active material may have a mass ratio of 93wt% to 96.9wt%, the anti-agglomerating agent may have a mass ratio of 0.1wt% to 0.5wt%, 0.2wt% to 0.5wt%, or 0.3wt% to 0.5wt%, the binder may have a mass ratio of 1wt% to 2wt%, and the conductive agent may have a mass ratio of 2wt% to 4.5wt%, based on the total mass of the positive electrode composition.
The kind of the binder and the conductive agent is not limited in the present application, and the binder and the conductive agent may be binders and conductive agents commonly used in the art. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluoroacrylate resin; the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
Without intending to be limited by any theory or explanation, the positive electrode composition comprises the positive electrode active material, the anti-agglomerating agent, the binder and the conductive agent, wherein the mass ratio of the positive electrode active material, the anti-agglomerating agent, the binder and the conductive agent is in the range, and the positive electrode composition can effectively prevent the generation of gel phenomenon when being applied to positive electrode slurry; the positive electrode plate is applied to a secondary battery, and can have good electron conduction performance, active ion transmission capability and good structural stability. Thus, the capacity of the secondary battery can be improved, and the secondary battery can be ensured to have good electrochemical performance.
In some embodiments, the positive electrode composition further includes a binder, a conductive agent, and carbon nanotubes. Alternatively, the positive electrode active material may have a mass ratio of 93wt% to 96wt%, the anti-agglomerating agent may have a mass ratio of 0.1wt% to 0.5wt%, 0.2wt% to 0.5wt%, or 0.3wt% to 0.5wt%, the carbon nanotube may have a mass ratio of 0.1wt% to 1wt%, the binder may have a mass ratio of 1wt% to 2wt%, and the conductive agent may have a mass ratio of 2wt% to 4wt%, based on the total mass of the positive electrode composition.
Examples of the binder and the conductive agent are described above and are not described here again.
Without intending to be limited by any theory or explanation, the positive electrode composition comprises the positive electrode active material, the anti-agglomerating agent, the carbon nano tube, the binder and the conductive agent, wherein the mass ratio is in the range, and the positive electrode composition can be applied to positive electrode slurry to effectively prevent the generation of gel phenomenon; the positive electrode plate is applied to a secondary battery, and can have good electron conduction performance, active ion transmission capability and good structural stability. Thus, the capacity of the secondary battery can be improved, and the secondary battery can be ensured to have good electrochemical performance.
In some embodiments, the mass ratio of lithium-containing phosphate to carbon nanotubes in the positive electrode composition is 1:0.003-1:0.01, for example, 1:0.003,1:0.004,1:0.005,1:0.006, 1:0.007,1:0.008,1:0.009,1:0.01.
Without intending to be limited by any theory or explanation, the mass ratio of the lithium-containing phosphate to the carbon nanotubes within the above range can effectively improve the conductive properties of the positive electrode composition, thereby enabling the secondary battery using the positive electrode composition of the present application to have a low Direct Current Resistance (DCR) and a long cycle life.
In some embodiments, the mass ratio of lithium-containing phosphate to anti-agglomerant may be 1:0.003 to 1:0.006, for example, 1:0.003,1:0.004,1:0.005,1:0.006.
Without intending to be limited by any theory or explanation, the mass ratio of the lithium-containing phosphate to the anti-agglomerating agent within the above range can enable the positive electrode composition to have higher energy density, lower cost and good electrochemical performance while effectively reducing the gelation phenomenon of the positive electrode slurry, thereby enabling the secondary battery to have high productivity, low cost and good electrochemical performance when applied to the secondary battery.
Positive electrode slurry
The second aspect of the present application provides a positive electrode slurry comprising a solvent and the positive electrode composition of the present application.
In some embodiments, the solvent may be Nitrogen Methyl Pyrrolidone (NMP).
In some embodiments, the solid component content of the positive electrode slurry may be 55wt% to 65wt%. The solid component content of the positive electrode slurry is in a proper range, so that the coating weight and the film thickness of the positive electrode plate can be conveniently controlled, and the energy density, the electrolyte infiltration rate and the electron conduction energy of the positive electrode plate are taken into account, and the electrochemical performance of the secondary battery is further improved.
In some embodiments, the viscosity of the positive electrode slurry may be 7000 mPa-s to 15000 mPa-s. The positive electrode slurry has proper viscosity, and is favorable for forming a coating with uniform thickness on the surface of the positive electrode current collector, so that the rate of the positive electrode plate is improved, and the productivity of the secondary battery is improved.
Method for preparing positive electrode slurry
The present application also provides a method for preparing the positive electrode slurry of the present application, comprising: the positive electrode material including the positive electrode composition of the present application is uniformly mixed with a solvent, thereby obtaining a positive electrode slurry.
In the method of the present application, the positive electrode material including the positive electrode composition of the present application is uniformly mixed with the solvent, and may include uniformly mixing each component in the positive electrode composition and then mixing with the solvent; the method may also include mixing the components of the positive electrode composition with a solvent in a certain order. As an example, the positive electrode active material, the conductive agent, the binder, and the solvent may be uniformly mixed, and then the carbon nanotube and the anti-agglomerating agent may be added, followed by adding the solvent to adjust the slurry viscosity.
In some embodiments, the solvent may be Nitrogen Methyl Pyrrolidone (NMP).
In some embodiments, the solid component content of the positive electrode slurry may be 55wt% to 65wt%. The solid component content of the positive electrode slurry is in a proper range, so that the coating weight and the film thickness of the positive electrode plate can be conveniently controlled, and the energy density, the electrolyte infiltration rate and the electron conduction energy of the positive electrode plate are taken into account, and the electrochemical performance of the secondary battery is further improved.
In some embodiments, the viscosity of the positive electrode slurry may be 7000 mPa-s to 15000 mPa-s. The positive electrode slurry has proper viscosity, and is favorable for forming a coating with uniform thickness on the surface of the positive electrode current collector, so that the rate of the positive electrode plate is improved, and the productivity of the secondary battery is improved.
Positive electrode plate
The third aspect of the application provides a positive electrode plate, which comprises a positive electrode current collector and a positive electrode film layer positioned on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises the positive electrode composition according to the application or is formed by drying the positive electrode slurry according to the application.
As an example, the positive electrode current collector has two surfaces opposing in its own thickness direction, and the positive electrode film layer is provided on either one or both of the two surfaces opposing the positive electrode current collector.
In some embodiments, the positive current collector may employ a metal foil or a composite current collector. For example, as the metal foil, aluminum foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
In some embodiments, the positive electrode sheet may be prepared by: dispersing the positive electrode composition of the present application and optionally other components in a solvent (e.g., NMP) to form a positive electrode slurry, or directly using the positive electrode slurry of the present application; and (3) coating the positive electrode slurry on a positive electrode current collector, and obtaining a positive electrode plate after the procedures of drying, cold pressing and the like.
In the positive electrode sheet of the present application, the substance contained in the positive electrode film layer may be sampled and tested during the preparation of the battery or from the prepared secondary battery, and the test method may be a method known in the art, for example, a test by a scanning electron microscope.
Secondary battery
The secondary battery, the battery module, the battery pack, and the electric device according to the present application will be described below with reference to the drawings.
In one embodiment of the present application, a secondary battery is provided.
In general, a secondary battery includes a positive electrode tab, a negative electrode tab, an electrolyte, and a separator. During the charge and discharge of the battery, active ions are inserted and extracted back and forth between the positive electrode plate and the negative electrode plate. The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The isolating film is arranged between the positive pole piece and the negative pole piece, and mainly plays a role in preventing the positive pole piece and the negative pole piece from being short-circuited, and meanwhile ions can pass through the isolating film.
[ Positive electrode sheet ]
The positive electrode sheet is selected from the positive electrode sheets according to the third aspect of the present application.
[ negative electrode sheet ]
The negative electrode plate comprises a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, wherein the negative electrode film layer comprises a negative electrode active material.
As an example, the anode current collector has two surfaces opposing in its own thickness direction, and the anode film layer is provided on either one or both of the two surfaces opposing the anode current collector.
In some embodiments, the negative electrode current collector may employ a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
In some embodiments, the anode active material may employ an anode active material for a battery, which is well known in the art. As an example, the anode 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 at least one selected from elemental silicon, silicon oxygen compounds, silicon carbon composites, silicon nitrogen composites, and silicon alloys. The tin-based material may be at least one selected from elemental tin, tin oxide, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery anode active material may be used. These negative electrode active materials may be used alone or in combination of two or more.
In some embodiments, the negative electrode film layer further optionally includes a binder. The binder may be at least one selected from Styrene Butadiene Rubber (SBR), polyacrylic acid (PAA), sodium Polyacrylate (PAAs), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium Alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).
In some embodiments, the negative electrode film layer further optionally includes a conductive agent. The conductive agent is at least one selected from superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
In some embodiments, the negative electrode film layer may optionally further include other adjuvants, such as thickening agents (e.g., sodium carboxymethyl cellulose (CMC-Na)), and the like.
In some embodiments, the negative electrode sheet may be prepared by: dispersing the above components for preparing the negative electrode sheet, such as a negative electrode active material, a conductive agent, a binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; and coating the negative electrode slurry on a negative electrode current collector, and obtaining a negative electrode plate after the procedures of drying, cold pressing and the like.
[ electrolyte ]
The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The application is not particularly limited in the kind of electrolyte, and may be selected according to the need. For example, the electrolyte may be liquid, gel, or all solid.
In some embodiments, the electrolyte is an electrolyte. The electrolyte includes an electrolyte salt and a solvent.
In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis-fluorosulfonyl imide, lithium bis-trifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalato borate, lithium difluorodioxaato phosphate, and lithium tetrafluorooxalato phosphate.
In some embodiments, the solvent may be selected from at least one 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, 1, 4-butyrolactone, sulfolane, dimethyl sulfone, methyl sulfone, and diethyl sulfone.
In some embodiments, the electrolyte further optionally includes an additive. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives capable of improving certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high or low temperature performance of the battery, and the like.
[ isolation Membrane ]
In some embodiments, a separator is further included in the secondary battery. The type of the separator is not particularly limited, and any known porous separator having good chemical stability and mechanical stability can be used.
In some embodiments, the material of the isolating film may be at least one selected from glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of the respective layers may be the same or different, and are not particularly limited.
In some embodiments, the positive electrode tab, the negative electrode tab, and the separator may be manufactured into an electrode assembly through a winding process or a lamination process.
In some embodiments, the secondary battery may include an outer package. The outer package may be used to encapsulate the electrode assembly and electrolyte described above.
In some embodiments, the outer package of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, or the like. The exterior package of the secondary battery may also be a pouch type pouch, for example. The material of the flexible bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.
The shape of the secondary battery is not particularly limited in the present application, and may be cylindrical, square, or any other shape. For example, fig. 2 is a secondary battery 5 of a square structure as one example.
In some embodiments, referring to fig. 3, the overpack may include a housing 51 and a cap assembly 53. The housing 51 may include a bottom plate and a side plate connected to the bottom plate, where the bottom plate and the side plate enclose a receiving chamber. The housing 51 has an opening communicating with the accommodating chamber, and the top cover assembly 53 can be provided to cover the opening to close the accommodating chamber. The positive electrode tab, the negative electrode tab, and the separator may be formed into the electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is enclosed in the accommodating chamber. The electrolyte is impregnated in the electrode assembly 52. The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and those skilled in the art may select according to specific practical requirements.
In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, and the specific number may be selected by one skilled in the art according to the application and capacity of the battery module.
Fig. 4 is a battery module 4 as an example. Referring to fig. 4, in the battery module 4, a plurality of secondary batteries 5 may be sequentially arranged in the longitudinal direction of the battery module 4. Of course, the arrangement may be performed in any other way. The plurality of secondary batteries 5 may be further fixed by fasteners.
Alternatively, the battery module 4 may further include a case having an accommodating space in which the plurality of secondary batteries 5 are accommodated.
In some embodiments, the above battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, and a specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.
Fig. 5 and 6 are battery packs 1 as an example. Referring to fig. 5 and 6, a battery case and a plurality of battery modules 4 disposed in the battery case may be included in the battery pack 1. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be covered on the lower box body 3 and forms a closed space for accommodating the battery module 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.
In addition, the application also provides an electric device which comprises at least one of the secondary battery, the battery module or the battery pack. The secondary battery, the battery module, or the battery pack may be used as a power source of the power consumption device, and may also be used as an energy storage unit of the power consumption device. The power utilization device may include mobile devices (e.g., cell phones, notebook computers, etc.), electric vehicles (e.g., electric-only 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., but is not limited thereto.
As the electricity consumption device, a secondary battery, a battery module, or a battery pack may be selected according to the use requirements thereof.
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 or the like. In order to meet the high power and high energy density requirements of the secondary battery by the power consumption device, a battery pack or a battery module may be employed.
As another example, the power consumption device may be a mobile phone, a tablet computer, a notebook computer, or the like. The device is generally required to be light and thin, and a secondary battery can be used as a power source.
Examples
Hereinafter, embodiments of the present application are described. The following examples are illustrative only and are not to be construed as limiting the application. The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
Examples 1 to 17
Preparation of cathode slurry
Adding lithium iron phosphate, a binder PVDF and a conductive agent Super P into a stirring tank according to a certain mass ratio, and stirring for 15 minutes at a revolution speed of 25rpm and a rotation speed of 800rpm to obtain a dry mixture;
Uniformly mixing the dry-mixed mixture with a solvent NMP to obtain initial positive electrode slurry with the solid component content of 60 wt%;
adding an anti-agglomerating agent and optional Carbon Nano Tubes (CNT) into the initial positive electrode slurry, uniformly stirring, and then regulating the viscosity to 7000 mPa.s-15000 mPa.s to obtain the positive electrode slurry.
For each exampleIs selected from the group consisting of compounds represented by formula 1. In various examples, particle size D of lithium iron phosphate 10 Ratio w of lithium iron phosphate in solid content of cathode slurry 1 Number average molecular weight M of the anti-coagulants n Ratio w of anti-coagulant to solid content of positive electrode slurry 2 Mass ratio of anti-agglomerating agent to lithium iron phosphateCNT type, CNT ratio w in solid content of positive electrode slurry 3 Mass ratio of CNT to lithium iron phosphate->As shown in table 1.
Comparative examples 1 to 3
Based on the preparation process of the positive electrode slurries of examples 1 to 17, positive electrode slurries of comparative examples 1 to 3 were prepared according to the preparation parameters of the positive electrode slurries shown in table 1.
Table 1: preparation parameters of examples 1 to 17 and comparative examples 1 to 3
The positive electrode slurries of examples 1 to 17 and comparative examples 1 to 3 were allowed to stand at 25℃for 48 hours, and then subjected to the following test, the test results of which are shown in Table 2 below.
(1) Test of the penetration degree of 150 mesh screen
The positive electrode slurry was sieved using a 150 mesh screen, and the degree of permeation of the positive electrode slurry in the 150 mesh screen was observed.
(2) Positive electrode slurry viscosity test
Using a rotary viscometer, selecting a rotor according to the viscosity of a sample, using a viscometer lifting frame to enable the viscometer to slowly descend, immersing the rotor in the slurry until marks on the rotor are leveled with the liquid level, and testing the temperature: 25 ℃, rotation speed: and (3) at 12rpm, pressing a measurement key to start measurement, and reading the viscosity value after the data is kept stable for 5 minutes.
Table 2: test parameters of the positive electrode slurries of examples 1 to 17 and comparative examples 1 to 3
| Sequence number | Degree of penetration of 150 mesh screen | Viscosity (mPa. S) |
| Example 1 | Completely penetrate through | 21000 |
| Example 2 | Completely penetrate through | 19500 |
| Example 3 | Completely penetrate through | 17000 |
| Example 4 | Completely penetrate through | 16000 |
| Example 5 | Completely penetrate through | 14000 |
| Example 6 | Completely penetrate through | 17000 |
| Example 7 | Completely penetrate through | 17000 |
| Example 8 | Completely penetrate through | 17000 |
| Example 9 | Not completely penetrate | 17000 |
| Example 10 | Not completely penetrate | 29000 |
| Example 11 | Completely penetrate through | 16000 |
| Example 12 | Completely penetrate through | 15000 |
| Example 13 | Not completely penetrate | 31000 |
| Example 14 | Completely penetrate through | 27000 |
| Example 15 | Completely penetrate through | 19000 |
| Example 16 | Completely penetrate through | 15000 |
| Example 17 | Completely penetrate through | 18000 |
| Comparative example 1 | Not penetrate through | 50000 |
| Comparative example 2 | Not penetrate through | 50000 |
| Comparative example 3 | Not penetrate through | 50000 |
The positive electrode slurries obtained in examples 1 to 17 and comparative examples 1 to 3 were prepared into secondary batteries as follows, respectively, and performance test was performed. The test results are shown in table 3 below.
(1) Preparation of secondary battery
Preparation of positive electrode plate
And uniformly coating the prepared positive electrode slurry on a positive electrode current collector, and then drying, cold pressing and cutting to obtain the positive electrode plate.
Preparation of negative electrode plate
The active material artificial graphite, conductive agent carbon black, binder Styrene Butadiene Rubber (SBR) and thickener sodium carboxymethylcellulose (CMC-Na) are mixed according to the weight ratio of 96.2:0.8:0.8:1.2 Dissolving in deionized water serving as a solvent, and uniformly mixing to prepare negative electrode slurry; and uniformly coating the negative electrode slurry on a negative electrode current collector copper foil once or a plurality of times, and drying, cold pressing and cutting to obtain a negative electrode plate.
Preparation of electrolyte
In an argon atmosphere glove box (H 2 O<0.1ppm，O 2 <0.1 ppm), mixing organic solvent Ethylene Carbonate (EC)/methyl ethyl carbonate (EMC) according to volume ratio of 3/7, adding 12.5% LiPF 6 Dissolving lithium salt in organic solvent, and stirring uniformly.
Isolation film
A polypropylene film was used as a separator.
Preparation of secondary battery
And sequentially stacking the positive electrode plate, the isolating film and the negative electrode plate, enabling the isolating film to be positioned between the positive electrode plate and the negative electrode plate to play a role of isolation, then winding to obtain an electrode assembly, welding a tab for the electrode assembly, loading the electrode assembly into an aluminum shell, baking at 100 ℃ for dewatering, injecting electrolyte, and sealing to obtain the uncharged battery. And the uncharged battery is subjected to the procedures of standing, hot and cold pressing, formation, shaping, capacity testing and the like in sequence, so that the secondary battery is obtained.
(2) Low temperature power test of secondary battery
Placing the secondary battery in an incubator, discharging to 50% SOC at 25 ℃ with a multiplying power of 1C, then adjusting the temperature of the incubator to-20 ℃, and placing for 2 hours, discharging for 120s with a multiplying power of 3C, placing for 30min, and taking the lowest voltage in the discharging process of 120s as a terminal voltage.
In addition, the time and the voltage values during the discharging process 120s are respectively taken as an abscissa axis and an ordinate axis, and the voltage value corresponding to each time is recorded, so as to obtain a low-temperature power test chart of the secondary battery. The low temperature power test charts of the secondary batteries of example 1 and comparative example 1 are shown in fig. 8 and 9, respectively.
Table 3: results of Performance test of examples 1 to 17 and comparative examples 1 to 3
| Sequence number | Terminal voltage (V) |
| Example 1 | 2.710 |
| Example 2 | 2.680 |
| Example 3 | 2.610 |
| Example 4 | 2.600 |
| Example 5 | 2.550 |
| Example 6 | 2.610 |
| Example 7 | 2.610 |
| Example 8 | 2.610 |
| Example 9 | 2.610 |
| Example 10 | 2.615 |
| Example 11 | 2.610 |
| Example 12 | 2.605 |
| Example 13 | 2.625 |
| Example 14 | 2.630 |
| Example 15 | 2.643 |
| Example 16 | 2.650 |
| Example 17 | 2.635 |
| Comparative example 1 | 2.610 |
| Comparative example 2 | 2.645 |
| Comparative example 3 | 2.645 |
As is clear from tables 1 to 3, the inclusion of the anti-agglomerating agent in the positive electrode slurry effectively reduces the gel degree of the positive electrode slurry. Specifically, as is clear from examples 1 to 5, the particle diameter D of lithium iron phosphate follows 10 The better the low-temperature power performance of the secondary battery prepared, but correspondingly, the coagulation of the positive electrode slurryThe greater the extent of glue. The anti-agglomerating agent is included in the positive electrode slurry, even if the particle diameter D of the lithium iron phosphate 10 The positive electrode slurry still has lower viscosity after being kept stand for 48 hours at 100nm, so that the low-temperature power performance of the lithium iron phosphate applied to the secondary battery can be fully exerted while the gel degree of the positive electrode slurry is lightened. From examples 3, 7 to 9 and 10 to 12, it is understood that the number average molecular weight of the anti-agglomerating agent is within the scope of the present application, the gel degree of the positive electrode slurry can be effectively reduced, and the gel degree of the positive electrode slurry is lower as the addition amount of the anti-agglomerating agent is increased. As is clear from examples 3 and 13 to 17, the inclusion of carbon nanotubes, particularly single-walled carbon nanotubes, in the positive slurry significantly improved the low-temperature power performance of the secondary battery.
In contrast, the positive electrode slurries of comparative examples 1 to 3 did not include the anti-agglomerating agent, and the viscosity of the positive electrode slurries was significantly increased after standing for 48 hours, and thus, the productivity and manufacturing cost of the secondary battery were not ideal as compared with examples 1 to 17.
The present application is not limited to the above embodiment. The above embodiments are merely examples, and embodiments having substantially the same configuration and the same effects as those of the technical idea within the scope of the present application are included in the technical scope of the present application. Further, various modifications that can be made to the embodiments and other modes of combining some of the constituent elements in the embodiments, which are conceivable to those skilled in the art, are also included in the scope of the present application within the scope not departing from the gist of the present application.
Claims (16)
1. A positive electrode composition for a positive electrode of a lithium battery, comprising a positive electrode active material and an anti-agglomerating agent, wherein the positive electrode active material comprises a lithium-containing phosphate, and the anti-agglomerating agent comprises a polymer comprising a phosphite group and an ether linkage in a molecular chain.
2. The positive electrode composition according to claim 1, wherein the lithium-containing phosphate comprises lithium iron phosphate, optionally having a particle size D 10 From 100nm to 800nm, more optionally, the particle diameter D of the lithium iron phosphate 10 200nm to 300nm, D 50 400nm to 600nm.
3. The positive electrode composition according to claim 1 or 2, wherein the anti-agglomerating agent has a number average molecular weight of 1000 to 10000, optionally 3000 to 8000.
4. The positive electrode composition according to any one of claims 1 to 3, wherein the anti-agglomerating agent comprises a compound represented by formula 1,
in formula 1, m is an integer from 20 to 180, optionally from 60 to 150, and n is an integer from 25 to 150, optionally from 50 to 120.
5. The positive electrode composition according to any one of claims 1 to 4, further comprising carbon nanotubes, optionally single-walled carbon nanotubes.
6. The positive electrode composition according to any one of claims 1 to 4, further comprising a binder and a conductive agent,
alternatively, the positive electrode active material may have a mass ratio of 93wt% to 96.9wt%, the anti-agglomerating agent may have a mass ratio of 0.1wt% to 0.5wt%, optionally 0.3wt% to 0.5wt%, the binder may have a mass ratio of 1wt% to 2wt%, and the conductive agent may have a mass ratio of 2wt% to 4.5wt%, based on the total mass of the positive electrode composition.
7. The positive electrode composition according to claim 5, further comprising a binder and a conductive agent,
alternatively, the positive electrode active material may have a mass ratio of 93wt% to 96wt%, the anti-agglomerating agent may have a mass ratio of 0.1wt% to 0.5wt%, optionally 0.3wt% to 0.5wt%, the carbon nanotube may have a mass ratio of 0.1wt% to 1wt%, the binder may have a mass ratio of 1wt% to 2wt%, and the conductive agent may have a mass ratio of 2wt% to 4wt%, based on the total mass of the positive electrode composition.
8. The positive electrode composition according to claim 5 or 7, wherein a mass ratio of the lithium-containing phosphate to the carbon nanotubes in the positive electrode composition is 1:0.003 to 1:0.01.
9. The positive electrode composition according to any one of claims 1 to 8, wherein the mass ratio of the lithium-containing phosphate to the anti-agglomerating agent in the positive electrode composition is 1:0.003 to 1:0.006.
10. A positive electrode slurry comprising a solvent and the positive electrode composition according to any one of claims 1 to 9.
11. The positive electrode slurry according to claim 10, wherein the positive electrode slurry satisfies at least one of:
(1) The solvent is nitrogen methyl pyrrolidone;
(2) The solid component content of the positive electrode slurry is 55-65wt%;
(3) The viscosity of the positive electrode slurry is 7000 mPas to 15000 mPas.
12. A positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer on at least one surface of the positive electrode current collector, wherein the positive electrode film layer comprises the positive electrode composition according to any one of claims 1 to 9, or the positive electrode film layer is a layer formed by drying the positive electrode slurry according to claim 10 or 11.
13. A secondary battery comprising the positive electrode tab of claim 12.
14. A battery module comprising the secondary battery according to claim 13.
15. A battery pack comprising the battery module of claim 14.
16. An electric device comprising at least one selected from the secondary battery according to claim 13, the battery module according to claim 14, and the battery pack according to claim 15.
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| CN202210282381.1A CN116825976A (en) | 2022-03-22 | 2022-03-22 | Positive electrode composition, positive electrode slurry, positive electrode sheet, secondary battery, battery module, battery pack, and electricity device |
| PCT/CN2023/076427 WO2023179256A1 (en) | 2022-03-22 | 2023-02-16 | Positive electrode composition, positive electrode slurry, positive electrode sheet, secondary battery, battery module, battery pack, and electrical device |
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| EP2908364B1 (en) * | 2012-10-10 | 2018-04-11 | Zeon Corporation | Method for producing positive electrode for secondary battery, secondary battery, and method for producing stack for secondary battery |
| WO2014192238A1 (en) * | 2013-05-29 | 2014-12-04 | 日本ゼオン株式会社 | Slurry composition for lithium-ion secondary battery positive electrode, production method for lithium-ion secondary battery positive electrode, lithium-ion secondary battery positive electrode, and lithium-ion secondary battery |
| CN108270010A (en) * | 2017-12-27 | 2018-07-10 | 镇江宜能新能源材料科技有限公司 | A kind of anode material of lithium battery and conductive additive |
| CN108539122B (en) * | 2018-03-26 | 2020-11-03 | 横店集团东磁股份有限公司 | Positive plate and lithium ion secondary battery comprising same |
| WO2021253302A1 (en) * | 2020-06-17 | 2021-12-23 | Guangdong Haozhi Technology Co. Limited | Conductive composition for secondary battery |
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