CN116960278B - Negative pole piece and preparation method thereof - Google Patents
Negative pole piece and preparation method thereof Download PDFInfo
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- CN116960278B CN116960278B CN202311212149.1A CN202311212149A CN116960278B CN 116960278 B CN116960278 B CN 116960278B CN 202311212149 A CN202311212149 A CN 202311212149A CN 116960278 B CN116960278 B CN 116960278B
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Classifications
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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
- 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
- H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- 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
- H01M4/139—Processes of manufacture
- H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- 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
- H01M2004/021—Physical characteristics, e.g. porosity, surface area
-
- 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
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
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Abstract
The applicationRelates to a negative pole piece and a preparation method thereof; the negative electrode plate comprises a current collector and a negative electrode coating, wherein the negative electrode coating is coated on the surface of the current collector. The negative electrode coating contains a negative electrode active material, and the negative electrode active material comprises graphite; the negative pole piece satisfies the following relation: 0.005.ltoreq.α.ltoreq.0.1, where α=ε.delta/. Rho. Wherein epsilon is the porosity of the negative electrode coating; delta is the particle diameter D of the negative electrode active material 50 Values in μm; ρ is the double-sided density of the negative electrode coating in g/m 2 . When alpha is 0.005-0.1, the negative electrode plate has good rapid charging capability, and meanwhile, lithium precipitation is not easy to occur in the charging process. And along with the gradual increase of alpha, the better the dynamic performance of the lithium ion battery is, the smaller the impedance in the lithium ion movement process is, and the lithium separation phenomenon is less likely to occur in the charging process.
Description
Technical Field
The application relates to the technical field of batteries, in particular to a negative electrode plate and a preparation method thereof.
Background
With the development of modernization, our daily life is more and more separated from the support of electric power, and correspondingly, various lithium ion batteries are also widely applied to various aspects of life. Such as cell phones, notebook computers, electric bicycles, electric vehicles, or even various energy storage devices. Therefore, the requirements of consumers on various performances of lithium ion batteries are increasingly improved, especially the requirements of people on battery charging capability are increasingly improved while pursuing electric quantity reserve capability.
A lithium ion battery is a typical secondary battery, in which lithium ions move from a positive electrode to a negative electrode and are inserted into a negative electrode tab during charging, and in which lithium ions move from the inside of the negative electrode tab to the surface of the negative electrode and are released from the negative electrode to the positive electrode during discharging. Therefore, the cathode pole piece is taken as an important component of the battery, and the charging capability, the cycle performance, the safety performance and the like of the lithium ion battery are generally determined.
In the fast charging process of lithium ion batteries, the most frequently occurring safety problem is the phenomenon of lithium precipitation. To avoid this phenomenon, it is common to increase the kinetic performance of lithium ion batteries by reducing the compacted density of the pole pieces, but with a loss of energy density; or the negative electrode binder is changed, so that the problems of battery cyclic expansion and the like can be caused while lithium precipitation is improved.
Therefore, a new battery anode is a technical problem to be solved in the art.
Disclosure of Invention
Based on the above, a first aspect of the present application is to provide a negative electrode tab, which helps to improve the charging capability of a lithium ion battery and improve the lithium precipitation phenomenon on the surface of a negative electrode by adjusting the co-ordination and fitting relationship between the porosity of the negative electrode coating, the particle size of the negative electrode active material and the double-sided density of the negative electrode coating.
A negative electrode tab, comprising:
current collector
The negative electrode coating is coated on the surface of the current collector;
wherein the negative electrode coating contains a negative electrode active material, and the negative electrode active material comprises graphite;
the negative pole piece satisfies the following relation: alpha is more than or equal to 0.005 and less than or equal to 0.1,
wherein,；
epsilon is the porosity of the negative electrode coating,
delta is the particle diameter D of the negative electrode active material 50 The values, in μm,
ρ is the double-sided density of the negative electrode coating in g/m 2 。
In some embodiments, the porosity epsilon of the negative electrode coating is 15% -60%.
In some embodiments, the porosity epsilon of the negative electrode coating is 20% -50%.
In some embodiments, the porosity epsilon of the negative electrode coating is 25% -45%.
In some of these embodiments, the particle diameter D of the anode active material 50 The value is 5 μm to 25 μm.
In some of these embodiments, the particle diameter D of the anode active material 50 The value is 5 μm to 20 μm.
In some embodiments, the negative electrode coating has a double sided density ρ of 80g/m 2 ~300 g/m 2 。
In some embodiments, the negative electrode coating has a double sided density ρ of 100g/m 2 ~250 g/m 2 。
In some embodiments, α is 0.01 to 0.08.
In some embodiments, the graphite comprises at least one of natural graphite, synthetic graphite.
The second aspect of the present application also provides a method for preparing the negative electrode plate of the first aspect of the present application, which includes the following steps:
mixing a negative electrode active material, a negative electrode binder and a negative electrode conductive agent to obtain a negative electrode slurry; and
coating the negative electrode slurry on the surface of a current collector, and drying to obtain a negative electrode plate;
wherein the negative electrode sheet satisfies the following relationship: 0.005 Alpha is more than or equal to 0.1,
；
epsilon is the porosity of the negative electrode coating,
delta is the particle diameter D of the negative electrode active material 50 The values, in μm,
ρ is the double-sided density of the negative electrode coating in g/m 2 。
The research shows that the increase of the porosity of the cathode coating is beneficial to improving the quick charging capability of the lithium ion battery and can also reduce the occurrence probability of the phenomenon of lithium precipitation on the surface of the cathode pole piece; but the surface density of the negative electrode coating layer is reduced, and the energy density of the battery is seriously lost. The reduction in the particle size of the negative electrode active material contributes to the improvement of the rapid charge capacity of the lithium ion battery, but also results in serious loss of the battery energy density. The increase in the areal density of the negative electrode coating is beneficial to improving the battery energy density, but can cause a decrease in porosity, which is detrimental to improving the rapid charge capability of the lithium ion battery.
The porosity epsilon of the negative electrode coating, the particle size delta of the negative electrode active substance and the double negative electrode coating are reasonably regulated and controlled by the negative electrode plateThe relation between the surface density rho is controlled to be more than or equal to 0.005 and less than or equal to 0.1, whereinThe lithium ion battery under the condition has small direct current internal resistance, better quick charging capability, difficult occurrence of lithium precipitation phenomenon on the surface of the negative electrode plate in the charging process and good cycle performance.
Detailed Description
Reference now will be made in detail to the embodiments of the application, one or more examples of which are described below. Each example is provided by way of explanation, not limitation, of the present application. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the scope or spirit of the present application. For example, features illustrated or described as part of one embodiment can be used on another embodiment to yield still a further embodiment.
Accordingly, it is intended that the present application cover such modifications and variations as fall within the scope of the appended claims and their equivalents. Other objects, features and aspects of the present application are disclosed in or are apparent from the following detailed description. It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only, and is not intended as limiting the broader aspects of the present application.
In the present application, the technical features described in an open manner include a closed technical scheme composed of the listed features, and also include an open technical scheme including the listed features.
In the present application, reference is made to numerical intervals, where the numerical intervals are considered to be continuous unless specifically stated, and include the minimum and maximum values of the range, and each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values of the range is included. Further, when multiple range description features or characteristics are provided, the ranges may be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood to include any and all subranges subsumed therein.
All embodiments and alternative embodiments of the present application may be combined with each other to form new solutions, unless specifically stated otherwise.
All technical features and optional technical features of the present application may be combined with each other to form new technical solutions, unless specified otherwise.
All steps of the present application may be performed sequentially or randomly, preferably sequentially, unless otherwise indicated. 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, it is mentioned that the method may further comprise step (c), meaning that step (c) may be added to the method in any order, e.g. the method may comprise steps (a), (b) and (c), may also comprise steps (a), (c) and (b), may also comprise steps (c), (a) and (b), etc.
Reference herein to "comprising" and "including" means open ended, as well as 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).
In one aspect, the present application relates to a negative electrode tab comprising a current collector and a negative electrode coating, wherein the negative electrode coating is applied to a surface of the current collector. The negative electrode coating contains a negative electrode active material, and the negative electrode active material comprises graphite; the negative pole piece satisfies the following relation: alpha is 0.005.ltoreq.alpha.ltoreq.0.1, where. Wherein epsilon is the porosity of the negative electrode coating;delta is the particle diameter D of the negative electrode active material 50 Values in μm; ρ is the double-sided density of the negative electrode coating in g/m 2 。
When alpha is 0.005-0.1, the lithium ion battery has lower direct current internal resistance and better quick charging capability, and meanwhile, the dynamic performance in the charging process is better, and the lithium precipitation phenomenon is not easy to occur. And along with the gradual increase of alpha, the better the dynamic performance of the battery cathode, the smaller the impedance in the lithium ion movement process, and the less likely the lithium precipitation phenomenon in the charging process.
In some embodiments, α is 0.005-0.1, including but not limited to 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, etc., preferably α is 0.01-0.08.
In some embodiments, the graphite comprises at least one of natural graphite, synthetic graphite.
In some embodiments, the porosity ε of the negative electrode coating is 15% -60%, including, but not limited to, 15%, 20%, 25%, 30%, 40%, 50%, 60%, etc.
At this time, the negative electrode plate has better dynamics performance. Along with the gradual increase of porosity, the more paths are reserved for lithium ions in the negative electrode, so that the conduction speed of the lithium ions in the negative electrode plate is gradually increased, and therefore, when the battery is charged rapidly, the lithium ions can be transmitted more rapidly and enter the negative electrode of the battery more easily, the generation probability of lithium precipitation phenomenon can be effectively reduced, the safety of the battery is improved, and the cycle performance of the battery is improved. In the liquid battery, the increase of the porosity can also improve the wettability of the negative electrode plate in the electrolyte, and further improve the conduction speed of lithium ions in the negative electrode plate; but at the same time, the interface reaction is increased, so that the reversible capacity of the negative electrode plate is reduced, the energy density loss of the battery is serious, and the cycle performance of the battery is influenced.
Preferably, the porosity epsilon of the anode coating is 20% -50%, more preferably, the porosity epsilon of the anode coating is 25% -45%.
In some of these embodiments, the particle diameter D of the anode active material 50 Values of 5 μm to 25 μm include, but are not limited to, 5 μm, 8 μm, 10 μm, 15 μm, 20 μm, 25 μm, etc.
On the premise of not changing other conditions, the cathode active material with smaller particle size is beneficial to reducing the transmission resistance of lithium ions in the cathode of the battery, so that the dynamic performance of the cathode pole piece is improved, and the quick charging capability of the battery is further improved. However, the smaller particle size can cause an increase in interfacial reaction, hinder the transmission efficiency of lithium ions, cause the loss of battery energy density, and further affect the cycle performance of the battery.
Preferably, the particle diameter D of the anode active material 50 The value is 5 μm to 20 μm.
In some embodiments, the negative electrode coating has a double sided density ρ of 80g/m 2 ~300 g/m 2 Including but not limited to 80g/m 2 、100 g/m 2 、120 g/m 2 、150 g/m 2 、200 g/m 2 、300 g/m 2 Etc.
On the premise of not changing other conditions, the increase of the double-sided density of the cathode coating increases the resistance during lithium ion transmission, is favorable for improving the energy density of the battery, but causes the reduction of the porosity, is unfavorable for improving the quick charging capability of the lithium ion battery, and can also lead to the deterioration of the cycle performance of the battery. On the contrary, as the double-sided density of the anode coating is reduced, the resistance in lithium ion transmission is reduced, which is favorable for improving the dynamic performance of the anode piece, but can cause serious damage to the energy density of the battery.
Preferably, the negative electrode coating has a double-sided density ρ of 100g/m 2 ~250g/m 2 。
The negative electrode plate controls alpha to be more than or equal to 0.005 to be less than or equal to 0.1 by reasonably regulating and controlling the relation among the porosity of the negative electrode coating, the particle size of the negative electrode active substance and the double-sided density of the negative electrode coating, whereinThe negative electrode plate has better quick charging capability, is not easy to generate lithium precipitation phenomenon in the charging process, and has higher battery cycle performance.
The second aspect of the present application also provides a method for preparing the negative electrode plate of the first aspect of the present application, which includes the following steps:
mixing a negative electrode active material, a negative electrode binder and a negative electrode conductive agent to obtain a negative electrode slurry; and
coating the negative electrode slurry on the surface of a current collector, and drying to obtain a negative electrode plate;
wherein the negative electrode sheet satisfies the following relationship: 0.005 Alpha is more than or equal to 0.1,the method comprises the steps of carrying out a first treatment on the surface of the Epsilon is the porosity of the anode coating, delta is the particle diameter D of the anode active material 50 Values in μm and ρ are the double-sided density of the negative electrode coating in g/m 2 。
It is understood that the present application is not particularly limited to the negative electrode current collector, as long as it has conductivity without causing chemical changes in the battery without departing from the inventive concept of the present application. The negative electrode current collector can be aluminum, copper, nickel or zinc simple substance or zinc alloy and other materials; the shape of the negative electrode current collector may be a foil shape, a plate shape, or a mesh shape.
In some of these embodiments, the negative electrode active material comprises graphite, including at least one of natural graphite, artificial graphite, and composite graphite.
The negative electrode binder is a polymer compound for adhering a negative electrode active material to a negative electrode current collector. The kind of the binder is not particularly limited, and the binder capable of binding and maintaining the negative electrode active material, enhancing the contact between the negative electrode active material and the negative electrode conductive agent and between the negative electrode active material and the negative electrode current collector on the basis of not departing from the inventive concept of the present application, thereby stabilizing the structure of the negative electrode tab, is within the scope of protection of the present application. Illustratively, the binder comprises a thermoplastic resin or a thermosetting resin. Such as Polytetrafluoroethylene (PTFE), sodium carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile-butadiene rubber (NBR), styrene-ethylene-butylene-styrene copolymer (SEBS), styrene-butadiene-styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, and the like.
The negative electrode conductive agent is used to further improve the conductivity of the negative electrode active material layer. The kind of the negative electrode conductive agent is not particularly limited in this application. The negative electrode conductive agent may be at least one of a carbon-based material, powdered nickel or other metal particles, or a conductive polymer, for example. Such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, channel black, acetylene black, carbon nanotubes, carbon nanofibers, polyaniline, polythiophene, polyacetylene, polypyrrole, poly (3, 4-ethylenedioxythiophene) polysulfstyrene, and the like.
In some embodiments, the method for preparing a negative electrode sheet of the present application further comprises a rolling step after the drying step.
It is understood that the process parameters related to the roll diameter, the roll pressure, the roll temperature and the like during rolling are not particularly limited, and the conventional adjustment scheme for adjusting the parameters such as the thickness of the negative electrode sheet and the porosity of the negative electrode coating is considered to be within the protection scope of the present application on the basis of not departing from the inventive concept of the present application. The present application also has no particular requirements for the drying process. Any known drying process can be used in the present application without departing from the inventive concept of the present application. By way of illustrative example only, and not by way of limitation, the drying process may be performed by baking, hot rolling, and the like.
In the preparation process, the porosity of the anode coating and the double-sided density of the anode coating are regulated and controlled by regulating the quality of the anode slurry, the surface area of the anode slurry coated on a current collector, the thickness of the anode slurry coated, the temperature and time of drying treatment, the rolling pressure and the like.
Embodiments of the present invention will be described more specifically below by way of examples. However, embodiments of the present invention are not limited to these examples only.
Example 1
(1) Preparation of negative electrode sheet
The mass ratio is 95:3:2 weighing artificial graphite, (CMC+SBR) and acetylene black, wherein the particle size D of the graphite 50 The negative electrode material is put into a vacuum stirrer to be stirred, meanwhile, deionized water serving as a solvent is added, and uniformly stirred to obtain uniformly mixed negative electrode slurry;
uniformly coating the negative electrode slurry on two surfaces of a copper foil, transferring the coated electrode sheet into a baking oven for drying, wherein the temperature in the baking oven is 140 ℃, and the drying time is 600 seconds to prepare a negative electrode sheet semi-finished product to be rolled;
and rolling the semi-finished negative electrode plate to be rolled, and cutting to obtain the negative electrode plate.
(2) Preparation of lithium ion batteries
According to the mass ratio of 95:3:2, weighing an anode active material NCM333, an electroconductive agent acetylene black and a binder PTFE, dissolving in a solvent NMP, uniformly stirring, coating on an aluminum foil, drying, rolling and cutting to obtain an anode plate;
and (3) laminating the positive pole piece, the negative pole piece and the diaphragm, putting the laminated positive pole piece, the laminated negative pole piece and the diaphragm into an aluminum plastic film, and injecting liquid into the aluminum plastic film to obtain the lithium ion battery.
(3) Detecting porosity of negative pole piece
The porosity epsilon of the negative electrode plate is obtained by a mass difference method, a plate punching machine is adopted to cut the plate into a circular plate with the radius r of 0.95 and cm, a thickness gauge is used for respectively measuring the thickness L0 of the plate L and the current collector, and the volume of the negative electrode active material on the cut plate is calculatedThe method comprises the steps of carrying out a first treatment on the surface of the The mass of the cut pole piece is weighed by a balance with the accuracy of 0.00001 and g and is marked as m1, the pole piece 1 h is soaked by hexadecane (completely immersed in the balance), the pole piece is taken out by tweezers, the filter paper is used for sucking the pole piece to constant weight, the mass of the pole piece is weighed by the balance and is marked as m2, and experimental data are substituted into a formula to calculate: />Wherein ρ0 is the density of hexadecane 0.7734 g/cm 3 And obtaining the porosity epsilon of the pole piece.
Examples 2 to 21 and comparative examples 1 to 3 adopt the same method as in example 1, artificial graphite particles with different particle diameters are selected, and when preparing the negative electrode sheet, the process parameters of coating, drying and rolling are adjusted so that the porosity of the negative electrode coating and the double-sided density of the negative electrode coating meet the requirements shown in Table 1, and different negative electrode sheets are respectively prepared.
Where the two-sided density of the anode coating = weight of anode slurry/surface area of the two sides of the anode film.
Wherein the porosity epsilon of the graphite in examples 1-9 is 20%, the porosity epsilon of the graphite in examples 10-12 is 30%, the porosity epsilon of the graphite in examples 13-18 is 40%, the porosity epsilon of the graphite in examples 19-20 is 50%, the porosity epsilon of the graphite in example 21 is 60%, the values of the porosity epsilon and other parameters and the parameters in the comparative examples are shown in table 1, and alpha is calculated and recorded in table 1.
Experimental example
(1) Room temperature 3C rate performance test:
the lithium ion batteries provided in examples and comparative examples were charged at 1C to a termination voltage, cut-off current was 0.05C, left standing for 30 min, and discharge capacities were recorded at 1C and 3C discharge voltages, respectively, and a 3C discharge capacity ratio of 1C discharge capacity was used to obtain a room temperature 3C rate discharge capacity.
(2) Testing of capacity retention rate at room temperature cycle 500 weeks:
the lithium ion batteries provided in examples and comparative examples were charged at a normal temperature with a prescribed current of 1C or a cut-off voltage of 0.05C, and left standing for 30 min;
discharging at 1C to discharge final pressure, recording discharge capacity, and standing for 30 min;
the charge and discharge process 500 cls was cycled and the data recorded.
(3) Lithium precipitation condition test:
the lithium ion batteries as the test objects were cycled to 1000 cls at 25 ℃, the lithium ion batteries provided in examples and comparative examples were respectively charged to 100% SOC at a rate of 1C, then the negative electrode sheet in the lithium ion batteries was disassembled, and the lithium precipitation condition of the surface of the negative electrode sheet was observed and recorded.
Among them, the lithium precipitation cases were classified into 3 types, namely, slight lithium precipitation, moderate lithium precipitation and severe lithium precipitation. The slight lithium precipitation represents that the area of a lithium precipitation area on the surface of the negative electrode plate is less than or equal to 10%; the area of the medium lithium precipitation area representing the surface lithium precipitation area of the negative electrode plate is 10% -50%, and the area of the serious lithium precipitation area representing the surface lithium precipitation area of the negative electrode plate is more than 50%.
The data of examples 1 to 21 and comparative examples 1 to 3 are compiled in Table 2.
As can be seen from the data in Table 1 and Table 2, the dynamic performance of the lithium ion battery is not matched with the porosity of the anode coating and the particle diameter D of the anode active material 50 The value and any one value of the double-sided density of the cathode coating are in positive correlation; taking examples 2 to 6 as an example, wherein the porosity of the anode coating layer and the particle diameter D of the anode active material 50 The value remains unchanged, and only the double-sided density of the cathode coating gradually increases, but the lithium precipitation condition of the lithium ion battery is not positively related to the lithium precipitation condition. That is, only changing the double-sided density of the negative electrode coating layer cannot directly cause the change of the lithium precipitation condition in the dynamic performance of the lithium ion battery. Similarly, other dynamic properties of lithium ion batteries, including 3C rate discharge performance, 500 cycle capacity retention, are not matched with the porosity of the anode coating, the particle size D of the anode active material 50 The values and the two-sided density of the cathode coating are in positive correlation.
Comparing examples 1-21 with comparative examples 1-3 further demonstrates that the parameters affecting the dynamic performance of the lithium ion battery are not parameters themselves, i.e., the porosity of the anode coating, the particle diameter D of the anode active material in comparative examples 1-3 50 Values or double-sided densities of the negative electrode coating can find consistent values in the examples, but because of too little or too much alphaThe dynamic performance of the lithium ion battery including 3C rate discharge performance, 500-cycle capacity retention and lithium evolution cannot be improved.
However, when alpha is more than or equal to 0.005 and less than or equal to 0.1, a subtle balance relation is formed between the performances, meanwhile, the whole lithium ion battery has better 3C rate discharge performance and 500-cycle capacity retention rate, and the phenomenon of lithium precipitation is obviously weakened. And observe the effect data of examples 1 and 4~6, along with the alpha value increases, the dynamic performance of lithium ion battery including 3C rate discharge performance and circulation 500 week capacity retention rate are all better, and the incidence of negative pole piece surface lithium precipitation phenomenon gradually declines.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples merely represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the invention. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application is to be determined by the claims appended hereto.
Claims (4)
1. The preparation method of the lithium ion battery is characterized in that the lithium ion battery comprises an anode, a cathode and a diaphragm, and comprises the following steps:
(1) Preparing a negative electrode plate;
(2) Preparing a positive electrode plate;
(3) Preparing a lithium ion battery: laminating the positive pole piece, the negative pole piece and the diaphragm, putting the laminated positive pole piece, the laminated negative pole piece and the diaphragm into an aluminum plastic film, and injecting liquid into the aluminum plastic film to obtain a lithium ion battery;
the negative electrode plate comprises a current collector and
the negative electrode coating is coated on the surface of the current collector;
wherein the negative electrode coating contains a negative electrode active material, and the negative electrode active material is graphite;
the negative electrode plate satisfies the following relation: 0.04 Alpha is more than or equal to 0.05 and less than or equal to 0,
wherein,；
epsilon is the porosity of the negative electrode coating,
delta is the particle diameter D of the negative electrode active material 50 The values, in μm,
ρ is the double-sided density of the negative electrode coating, and the unit is g/m 2 ；
The porosity epsilon of the negative electrode coating is 50% -60%;
particle diameter D of the negative electrode active material 50 The value is 5-25 μm;
the double-sided density rho of the cathode coating is 80g/m 2 ~300 g/m 2 。
2. The production method according to claim 1, wherein the anode active material has a particle diameter D 50 The value is 5 μm to 20 μm.
3. The method of claim 1, wherein the negative electrode coating has a double-sided density ρ of 100g/m 2 ~250 g/m 2 。
4. The method of claim 1, wherein the graphite comprises at least one of natural graphite, artificial graphite, and composite graphite.
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| CN115004418A (en) * | 2020-07-31 | 2022-09-02 | 宁德时代新能源科技股份有限公司 | Secondary battery, method for manufacturing the same, and battery module, battery pack, and device containing the same |
| CN115377353A (en) * | 2022-10-27 | 2022-11-22 | 中创新航科技股份有限公司 | Negative plate and battery using same |
| CN116169249A (en) * | 2023-04-20 | 2023-05-26 | 江苏正力新能电池技术有限公司 | Negative electrode plate, secondary battery and electric equipment |
| CN116470003A (en) * | 2023-03-13 | 2023-07-21 | 安徽得壹能源科技有限公司 | Pre-lithiated negative electrode piece and lithium ion battery |
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| CN115004418A (en) * | 2020-07-31 | 2022-09-02 | 宁德时代新能源科技股份有限公司 | Secondary battery, method for manufacturing the same, and battery module, battery pack, and device containing the same |
| CN115377353A (en) * | 2022-10-27 | 2022-11-22 | 中创新航科技股份有限公司 | Negative plate and battery using same |
| CN116470003A (en) * | 2023-03-13 | 2023-07-21 | 安徽得壹能源科技有限公司 | Pre-lithiated negative electrode piece and lithium ion battery |
| CN116169249A (en) * | 2023-04-20 | 2023-05-26 | 江苏正力新能电池技术有限公司 | Negative electrode plate, secondary battery and electric equipment |
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