CN116053412A - Lithium ion battery negative plate - Google Patents

Lithium ion battery negative plate Download PDF

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Publication number
CN116053412A
CN116053412A CN202310043009.XA CN202310043009A CN116053412A CN 116053412 A CN116053412 A CN 116053412A CN 202310043009 A CN202310043009 A CN 202310043009A CN 116053412 A CN116053412 A CN 116053412A
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negative electrode
electrode active
active material
conductive agent
active coating
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Inventor
王雪
童路攸
郑浩
郑晓帆
马晨星
陈丽鲜
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Zhejiang Hengyuan New Energy Technology Co Ltd
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Zhejiang Hengyuan New Energy Technology Co Ltd
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Priority to CN202310043009.XA priority Critical patent/CN116053412A/en
Publication of CN116053412A publication Critical patent/CN116053412A/en
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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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • 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
    • 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

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  • 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 invention discloses a lithium ion battery negative plate, which comprises a negative current collector and a negative active layer arranged on the negative current collector, wherein the negative active layer comprises a first negative active coating and a second negative active coating, the first negative active coating is arranged on the negative current collector, and the second negative active coating is arranged on the first negative active coating; the negative electrode active layer includes a negative electrode active material and a conductive agent, the conductive agent content of the first negative electrode active coating is greater than the conductive agent content of the second negative electrode active coating, the negative electrode active material includes a first negative electrode active material and a second negative electrode active material, and the proportion of the first negative electrode active material of the first negative electrode active coating is greater than the proportion of the first negative electrode active material of the second negative electrode active coating. The invention utilizes the double-layer negative electrode active coatings with different proportions of active materials, different contents of conductive agents and different porosities to manufacture the negative electrode plate, thereby not only realizing the improvement of the multiplying power performance of the negative electrode plate, but also reducing the loss of the energy density of the negative electrode plate.

Description

Lithium ion battery negative plate
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a lithium ion battery negative plate.
Background
The lithium ion battery has the advantages of high energy density, good cycle performance, long service life, low self-discharge, no memory effect and the like, gradually occupies larger application markets in the aspects of energy storage, power batteries, 3C electrons and the like, and has wide application prospect.
The negative electrode plate is taken as an important component in the lithium ion battery, is one of main short plates for limiting the performances of energy density, multiplying power and the like of the battery, is often required to be as superior as possible at present, the energy density of the battery mainly depends on the total amount of active substances in the electrode plate and the utilization rate of material performance, and the conventional way for improving the multiplying power performance is to increase the content of a conductive agent or reduce the surface density, so that the multiplying power performance can be improved, but the energy density is sacrificed, and the cost is increased.
Disclosure of Invention
In view of the above, the present invention provides a negative electrode sheet for a lithium ion battery, which is manufactured by a double-layer negative electrode active coating layer with different active material ratios, different conductive agent contents, and different porosities, and can improve the rate performance and reduce the loss of energy density.
According to some embodiments of the invention, the negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on the negative electrode current collector, the negative electrode active layer including a first negative electrode active coating disposed on the negative electrode current collector and a second negative electrode active coating disposed on the first negative electrode active coating; the negative electrode active layer comprises a negative electrode active material and a conductive agent, the conductive agent content of the first negative electrode active coating is larger than the conductive agent content of the second negative electrode active coating, the negative electrode active material comprises a first negative electrode active material and a second negative electrode active material, and the proportion of the first negative electrode active material of the first negative electrode active coating is larger than that of the second negative electrode active coating.
Further, because the energy density of the battery mainly depends on the content of active materials in the pole piece, in the invention, the first negative electrode active coating is arranged on the negative electrode current collector, the second negative electrode active coating is arranged on the first negative electrode active coating, and the proportion of the first negative electrode active materials of the first negative electrode active coating is larger than that of the second negative electrode active coating.
Further, as the content of the conductive agent directly influences the rate performance of the battery, in the invention, the content of the conductive agent of the first negative electrode active coating is larger than that of the conductive agent of the second negative electrode active coating, the conductive agent of the bottom layer can form more conductive paths with the current collector, and the electron transmission resistance of the negative electrode plate is reduced, so that the rate performance and the cycle stability of the battery are improved.
In some embodiments of the invention, the second negative electrode active coating has a porosity greater than the first negative electrode active coating.
Further, as the second anode active coating is arranged on the first anode active coating, and the porosity of the second anode active coating is larger than that of the first anode active coating, electrolyte can more rapidly permeate to deeper places along a pore channel, the surface area of the anode active coating contacting the electrolyte is increased, the whole anode active coating is more fully soaked, the effect of active substances can be better exerted in the charging and discharging process, meanwhile, the kinetic obstruction of lithium ions in the charging and discharging process is reduced, the movement path is better, the intercalation and deintercalation process can be more rapidly realized, and the charging and discharging performance of the lithium battery under high multiplying power can be remarkably enhanced.
In some embodiments of the present invention, a binder is further included in the anode active layer, and particle sizes and proportions of the anode active material, the conductive agent, and the binder in the first anode coating layer and the second anode active coating layer are different.
Further, it is because the particle diameters and proportions of the anode active material, the conductive agent, and the binder are different, and thus the first anode active coating layer and the second anode active coating layer, which are different in porosity, are structured.
In some embodiments of the invention, the negative electrode active material includes at least 1 of graphite, soft carbon, and hard carbon.
In some embodiments of the invention, the negative electrode active material includes the first negative electrode active material including graphite and the second negative electrode active material including soft carbon or hard carbon.
In some embodiments of the invention, the conductive agent comprises at least 2 of conductive carbon black, acetylene carbon black, vapor grown carbon fiber, graphene, and carbon nanotubes.
In some embodiments of the present invention, the conductive agent includes a first conductive agent including at least 1 of conductive carbon black and acetylene carbon black and a second conductive agent including at least 1 of vapor grown carbon fiber, graphene, and carbon nanotubes.
In some embodiments of the invention, the binder comprises at least 2 of sodium carboxymethyl cellulose, styrene-butadiene rubber, and polyacrylic acid.
Further, in some embodiments of the invention, the negative electrode active layer is present at 100% by weight:
in the first negative electrode active coating layer: 90-95% of the first negative electrode active material, 3-5% of the second negative electrode active material, 0.5-2% of the first conductive agent, 0.5-2% of the second conductive agent and 1-3% of the binder;
in the second anode active coating: the first negative electrode active material accounts for 80-88%, the second negative electrode active material accounts for 7-15%, the first conductive agent accounts for 0.5-1.5%, the second conductive agent accounts for 0.5-1.5%, and the binder accounts for 1-3%.
Further, the first negative electrode active material in the first negative electrode active coating layer comprises 90%, 91%, 92%, 93%, 94%, 95%; the second negative electrode active material comprises 3%, 4%, 5%, the first conductive agent comprises 0.5%, 1%, 1.5%, 2%, the second conductive agent comprises 0.5%, 1%, 1.5%, 2%, and the binder comprises 1%, 2%, 3%.
Further, the proportion of the first negative electrode active material in the second negative electrode active coating layer includes 80%, 82%, 84%, 86%, 88%, the proportion of the second negative electrode active material is 7%, 8%, 10%, 12%, 14%, 15%, the proportion of the first conductive agent is 0.5%, 1%, 1.5%, the proportion of the second conductive agent is 0.5%, 1%, 1.5%, and the proportion of the binder is 1%, 2%, 3%.
In some embodiments of the invention, the first negative electrode active material has a particle size that is smaller than a particle size of the second negative electrode active material.
Further, since the first anode active material has a higher ratio of the first anode active material to the second anode active material in both the first anode active coating layer and the second anode active coating layer, and in the present invention, the first anode active material has a smaller particle diameter than the second anode active material, the first anode active coating layer has a smaller porosity than the second anode active coating layer.
In some embodiments of the invention, the gram-capacity of the first negative electrode active material is greater than the gram-capacity of the second negative electrode active material.
Further, in the present invention, since the gram capacity of the first anode active coating layer is larger than the gram capacity of the second anode active coating layer and the anode active material proportion of the first anode active coating layer is larger than the anode active material proportion of the second anode active coating layer, the energy density of the first anode active coating layer is higher than the energy density of the second anode active coating layer, and the energy density of the anode sheet as a whole is improved.
According to the invention, the first negative electrode active coating and the second negative electrode active coating which are different in proportion of active substances, different in content of conductive agents and different in porosity are built on the negative electrode current collector by utilizing the negative electrode active substances, the conductive agents and the binding agents with different particle sizes and proportions, so that the negative electrode plate with high rate capability and reduced energy density loss is prepared.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Detailed Description
The invention will now be described with reference to specific examples, which are intended to be illustrative only and not limiting in any way. The reagents used in the examples are commercially available as usual unless otherwise specified.
The negative electrode current collector is copper foil, and the thickness of the negative electrode current collector 10 is 6-12um. And simultaneously coating the first negative electrode active coating and the second negative electrode active coating on the negative electrode current collector by adopting double-layer coating equipment to form a negative electrode plate. The surface density of the negative plate is about 85-95g/m 2 A compacted density of about 1.3 to 1.4g/cm 3 。
Example 1:
the negative electrode plate comprises a negative electrode current collector, a first negative electrode active coating and a second negative electrode active coating, wherein the first negative electrode active coating and the second negative electrode active coating are arranged on the negative electrode current collector, the second negative electrode active coating is arranged on the first negative electrode active coating, and the first negative electrode active coating comprises the following raw materials in percentage by weight: 90.6% of a first negative electrode active material, namely artificial graphite, 4% of a second negative electrode active material, namely hard carbon, 1.4% of a first conductive agent, namely acetylene black, 1% of a second conductive agent, namely vapor grown carbon fiber, and 3% of a binder (sodium carboxymethyl cellulose 1.2% and styrene-butadiene rubber 1.8%); the second negative electrode active coating comprises the following raw materials in percentage by weight: 83.2% of first negative electrode active material-artificial graphite, 12% of second negative electrode active material-hard carbon, 1.0% of first conductive agent-acetylene black, 0.8% of second conductive agent-vapor grown carbon fiber and 3% of binder (sodium carboxymethyl cellulose 1.2% and styrene-butadiene rubber 1.8%).
Example 2:
the negative electrode plate comprises a negative electrode current collector, a first negative electrode active coating and a second negative electrode active coating, wherein the first negative electrode active coating and the second negative electrode active coating are arranged on the negative electrode current collector, the second negative electrode active coating is arranged on the first negative electrode active coating, and the first negative electrode active coating comprises the following raw materials in percentage by weight: 91% of first negative electrode active material-artificial graphite, 4% of second negative electrode active material-hard carbon, 1.2% of first conductive agent-acetylene black, 0.8% of second conductive agent-vapor grown carbon fiber and 3% of binder (sodium carboxymethylcellulose 1.2% and styrene-butadiene rubber 1.8%); the second negative electrode active coating comprises the following raw materials in percentage by weight: 83.2% of first negative electrode active material-artificial graphite, 12% of second negative electrode active material-hard carbon, 1.0% of first conductive agent-acetylene black, 0.8% of second conductive agent-vapor grown carbon fiber and 3% of binder (sodium carboxymethyl cellulose 1.2% and styrene-butadiene rubber 1.8%).
Example 3:
the negative electrode plate comprises a negative electrode current collector, a first negative electrode active coating and a second negative electrode active coating, wherein the first negative electrode active coating and the second negative electrode active coating are arranged on the negative electrode current collector, the second negative electrode active coating is arranged on the first negative electrode active coating, and the first negative electrode active coating comprises the following raw materials in percentage by weight: 91% of first negative electrode active material-artificial graphite, 4% of second negative electrode active material-hard carbon, 1.2% of first conductive agent-acetylene black, 0.8% of second conductive agent-vapor grown carbon fiber and 3% of binder (sodium carboxymethylcellulose 1.2% and styrene-butadiene rubber 1.8%); the second negative electrode active coating comprises the following raw materials in percentage by weight: 80.2% of first negative electrode active material-artificial graphite, 15% of second negative electrode active material-hard carbon, 1.0% of first conductive agent-acetylene black, 0.8% of second conductive agent-vapor grown carbon fiber and 3% of binder (sodium carboxymethyl cellulose 1.2% and styrene-butadiene rubber 1.8%).
Example 4:
the negative electrode plate comprises a negative electrode current collector, a first negative electrode active coating and a second negative electrode active coating, wherein the first negative electrode active coating and the second negative electrode active coating are arranged on the negative electrode current collector, the second negative electrode active coating is arranged on the first negative electrode active coating, and the first negative electrode active coating comprises the following raw materials in percentage by weight: 91% of first negative electrode active material-artificial graphite, 4% of second negative electrode active material-hard carbon, 1.2% of first conductive agent-acetylene black, 0.8% of second conductive agent-vapor grown carbon fiber and 3% of binder (sodium carboxymethylcellulose 1.2% and styrene-butadiene rubber 1.8%); the second negative electrode active coating comprises the following raw materials in percentage by weight: 88.2% of first negative electrode active material-artificial graphite, 7% of second negative electrode active material-hard carbon, 1.0% of first conductive agent-acetylene black, 0.8% of second conductive agent-vapor grown carbon fiber and 3% of binder (sodium carboxymethyl cellulose 1.2% and styrene-butadiene rubber 1.8%).
Comparative example 1:
the negative plate comprises the following raw materials in percentage by weight: 90.6% of first negative electrode active material-artificial graphite, 4% of second negative electrode active material-hard carbon, 1.4% of first conductive agent-acetylene black, 1% of second conductive agent-vapor grown carbon fiber and 3% of binder (sodium carboxymethyl cellulose 1.2% and styrene-butadiene rubber 1.8%).
Comparative example 2:
the negative plate comprises the following raw materials in percentage by weight: 83.2% of first negative electrode active material-artificial graphite, 12% of second negative electrode active material-hard carbon, 1.0% of first conductive agent-acetylene black, 0.8% of second conductive agent-vapor grown carbon fiber and 3% of binder (sodium carboxymethyl cellulose 1.2% and styrene-butadiene rubber 1.8%).
Comparative example 3:
the negative electrode plate comprises a negative electrode current collector, a first negative electrode active coating and a second negative electrode active coating, wherein the first negative electrode active coating and the second negative electrode active coating are arranged on the negative electrode current collector, the second negative electrode active coating is arranged on the first negative electrode active coating, and the first negative electrode active coating comprises the following raw materials in percentage by weight: 88.2% of a first negative electrode active material, namely artificial graphite, 7% of a second negative electrode active material, namely hard carbon, 1.0% of a first conductive agent, namely acetylene black, 0.8% of a second conductive agent, namely vapor grown carbon fiber, and 3% of a binder (sodium carboxymethyl cellulose 1.2% and styrene butadiene rubber 1.8%); the second negative electrode active coating comprises the following raw materials in percentage by weight: 91% of first negative electrode active material-artificial graphite, 4% of second negative electrode active material-hard carbon, 1.2% of first conductive agent-acetylene black, 0.8% of second conductive agent-vapor grown carbon fiber and 3% of binder (sodium carboxymethyl cellulose 1.2% and styrene-butadiene rubber 1.8%).
Comparative example 4:
the negative electrode plate comprises a negative electrode current collector, a first negative electrode active coating and a second negative electrode active coating, wherein the first negative electrode active coating and the second negative electrode active coating are arranged on the negative electrode current collector, the second negative electrode active coating is arranged on the first negative electrode active coating, and the first negative electrode active coating comprises the following raw materials in percentage by weight: 80.2% of a first negative electrode active material, namely artificial graphite, 15% of a second negative electrode active material, namely hard carbon, 1.0% of a first conductive agent, namely acetylene black, 0.8% of a second conductive agent, namely vapor grown carbon fiber, and 3% of a binder (sodium carboxymethyl cellulose 1.2% and styrene-butadiene rubber 1.8%); the second negative electrode active coating comprises the following raw materials in percentage by weight: 91% of first negative electrode active material-artificial graphite, 4% of second negative electrode active material-hard carbon, 1.2% of first conductive agent-acetylene black, 0.8% of second conductive agent-vapor grown carbon fiber and 3% of binder (sodium carboxymethyl cellulose 1.2% and styrene-butadiene rubber 1.8%).
The negative electrode sheets of example 1, example 2, example 3, example 4, comparative example 1, comparative example 2, comparative example 3, and comparative example 4 were prepared according to the button cell type, and the preparation process was the same as that of the negative electrode sheets of example 1, example 2, example 3, example 4, comparative example 1, comparative example 2, comparative example 3, and comparative example 4, respectively. And packaging the lithium sheet, the negative electrode sheet, the diaphragm and the electrolyte, and testing the gram capacity and the multiplying power performance of the buckling electricity.
1. Testing of actual gram Capacity at Room temperature
The button cells prepared in example 1, example 2, example 3, example 4 and comparative example 1, comparative example 2, comparative example 3 and comparative example 4 were subjected to charge-discharge cycle at normal temperature and at 0.1C current for 3 to 5 cycles, and the actual gram capacity of the negative electrode sheet was calculated, and specific test results are shown in table 1:
TABLE 1 results of testing the actual gram Capacity of the negative electrode sheets in examples 1-4 and comparative examples 1-4
Figure BDA0004051210890000081
2. Discharge test at room temperature at different magnifications
The button cells prepared in example 1, example 2, example 3, example 4 and comparative example 1, comparative example 2, comparative example 3 and comparative example 4 were subjected to discharge tests at normal temperature at different rates of 0.1C/1C/2C/3C/5C/10C, respectively, and data of capacity percentages of the negative electrode sheet at different rates of discharge were recorded as shown in table 2.
TABLE 2 discharge capacity percentage at different rates for the negative electrode sheets of examples 1-4 and comparative examples 1-4
Discharge rate Example 1 Example 2 Example 3 Example 4 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4
0.1C 100.00％ 100.00％ 100.00％ 100.00％ 100.00％ 100.00％ 100.00％ 100.00％
1C 98.91％ 98.51％ 98.99％ 98.06％ 97.52％ 98.68％ 97.61％ 97.59％
2C 98.45％ 98.12％ 98.67％ 97.89％ 96.65％ 98.18％ 96.68％ 96.72％
3C 98.17％ 97.96％ 98.41％ 97.37％ 95.60％ 98.05％ 95.72％ 95.68％
5C 98.13％ 97.74％ 98.26％ 96.64％ 94.77％ 97.96％ 94.75％ 94.79％
10C 97.76％ 97.34％ 98.01％ 94.88％ 90.32％ 97.53％ 91.07％ 91.18％
3. Charging test of different multiplying powers at room temperature
The button cells prepared in example 1, example 2, example 3, example 4 and comparative examples 1, comparative example 2, comparative example 3 and comparative example 4 were respectively subjected to charging test at normal temperature under different multiplying powers of 0.1C/1C/2C/3C, and capacity percentage data recorded for the negative electrode sheet when charged under different multiplying powers are shown in Table 3.
TABLE 3 percent different rate charge capacities for the negative plates of examples 1-4 and comparative examples 1-4
Charging rate Example 1 Example 2 Example 3 Example 4 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4
0.1C 100.00％ 100.00％ 100.00％ 100.00％ 100.00％ 100.00％ 100.00％ 100.00％
1C 70.32％ 69.98％ 70.35％ 68.28％ 65.23％ 70.15％ 65.73％ 65.85％
2C 52.37％ 50.68％ 53.11％ 47.57％ 40.58％ 51.46％ 40.93％ 40.79％
3C 40.55％ 39.30％ 40.93％ 33.75％ 20.79％ 41.29％ 21.35％ 21.48％
The discharge gram capacity of the negative electrode plate directly influences the energy density of the negative electrode plate, the higher the discharge gram capacity is, the higher the energy density of the negative electrode plate is, and vice versa, while the charging capacity percentage at different multiplying powers directly influences the multiplying power performance of the negative electrode plate, the higher the capacity percentage is, the higher the multiplying power performance is, namely, the faster the charging or discharging is.
As is clear from tables 1 to 3, the discharge gram capacity of comparative example 1 is about 6mAh/g higher than that of comparative example 2, but the capacity percentage of charging and discharging at different rates of comparative example 1 is lower than that of comparative example 2, about 7% lower at 10C rate and about 20% lower at 3C rate, i.e., the energy density of the negative electrode sheet of comparative example 1 is much higher than that of comparative example 2, but the charge-discharge rate performance of comparative example 1 is much lower than that of comparative example 2, so that it can be seen that in the prior art, the single-layer negative electrode sheet cannot be guaranteed to have both higher energy density and higher charge-discharge rate performance.
Comparative examples 3 to 4 are double-layered negative plates, and as can be seen from tables 1 to 3, the gram discharge capacity of comparative examples 3 and 4 is lower than that of comparative example 1, but the percentage of the charge-discharge capacity of comparative examples 3 and 4 at different rates is similar to that of comparative example 1 and lower than that of comparative example 2; meanwhile, the gram discharge capacity of comparative examples 3 and 4 is similar to that of examples 4 and 3, but the capacity percentage of charge and discharge of example 3 is higher than that of comparative example 4 at different rates, about 7% at 10C rate and about 19% at 3C rate; example 4 the percentage capacity of charge and discharge at different rates was about 4% higher at 10C rate and about 12% higher at 3C at charge than comparative example 3 at different rates; it can also be seen from this that the proportion of the first anode active material of the first anode active coating is greater than that of the second anode active coating, and the porosity of the first anode active coating is smaller than that of the second anode active coating, which is favorable to reducing the loss of the energy density of the anode sheet, while ensuring the improvement of the rate performance.
Examples 1 to 4 are prepared negative electrode sheets having a double-layered negative electrode active coating layer according to the present invention, and as can be seen from tables 1 to 3, examples 1 to 4 have a discharge gram capacity which is not much different from that of comparative example 1, and the percentage of charge/discharge capacity at different rates is higher than that of comparative example 1 by about 7% at 10C rate and about 20% at 3C rate; examples 1-4 have a discharge gram capacity 3mAh/g higher than that of comparative example 2, and the percentage capacity of charge and discharge at high rate is not much different from that of comparative example 2 at high rate; comparative examples 1-4, with different formulation ratios, the maximum discharge gram capacities differ by about 2mAh/g, the maximum discharge rates differ by about 2%, and the maximum charge rates differ by about 7%; it can be seen that, compared with comparative examples 1 to 4, the examples 1 to 4 achieve a balance between the discharge gram capacity and the percentage capacity of charge and discharge at high rate, not only can reduce the loss of the energy density of the negative electrode sheet, but also can ensure the improvement of the rate performance.
The negative plate can achieve the technical effects because the double-layer negative active coating is adopted, the pore channel of the upper-layer negative active coating is improved, the lithium ion movement path is optimized, and the intercalation and deintercalation processes can be realized more rapidly, so that the charge and discharge performance of the lithium battery under high multiplying power can be obviously enhanced; meanwhile, gram capacity of active substances of the lower-layer anode active coating is increased, capacity of the anode plate is increased, energy density of the battery is increased, and cost is reduced; in addition, the proportion of the conductive agent in the lower-layer negative electrode active coating is optimized, more conductive paths are formed with the current collector, the electrode plate electron transmission resistance is reduced, and the rate performance and the cycle stability of the battery are optimized.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.

Claims (9)

1. The lithium ion battery negative plate is characterized by comprising a negative electrode current collector and a negative electrode active layer arranged on the negative electrode current collector ， The negative electrode active layer comprises a first negative electrode active coatingA layer and a second anode active coating, the first anode active coating disposed on the anode current collector, the second anode active coating disposed on the first anode active coating; the negative electrode active layer comprises a negative electrode active material and a conductive agent, the conductive agent content of the first negative electrode active coating is larger than the conductive agent content of the second negative electrode active coating, the negative electrode active material comprises a first negative electrode active material and a second negative electrode active material, and the proportion of the first negative electrode active material of the first negative electrode active coating is larger than that of the second negative electrode active coating.
2. The lithium-ion battery negative electrode sheet of claim 1, wherein the second negative electrode active coating has a porosity greater than the first negative electrode active coating.
3. The negative electrode sheet for a lithium ion battery according to claim 1, wherein the negative electrode active layer further comprises a binder, and particle diameters and proportions of the binder, the negative electrode active material, and the conductive agent are different.
4. The lithium-ion battery negative electrode sheet of claim 1, wherein the first negative electrode active material comprises graphite and the second negative electrode active material comprises soft carbon or hard carbon.
5. The negative electrode sheet of lithium ion battery of claim 1, wherein the conductive agent comprises at least 2 of conductive carbon black, acetylene carbon black, vapor grown carbon fiber, graphene, and carbon nanotubes.
6. The negative electrode sheet of lithium ion battery of claim 5, wherein the conductive agent comprises a first conductive agent comprising at least 1 of conductive carbon black and acetylene carbon black and a second conductive agent comprising at least 1 of vapor grown carbon fiber, graphene, and carbon nanotubes.
7. The lithium ion battery negative electrode sheet of claim 3, wherein the binder comprises at least 2 of sodium carboxymethyl cellulose, styrene-butadiene rubber, and polyacrylic acid.
8. The lithium-ion battery negative electrode sheet of claim 6, characterized in that the negative electrode active layer comprises, by weight, 100%:
in the first negative electrode active coating layer: 90-95% of a first negative electrode active material, 3-5% of a second negative electrode active material, 0.5-2% of a first conductive agent, 0.5-2% of a second conductive agent and 1-3% of a binder;
in the second anode active coating: the first negative electrode active material accounts for 80-88%, the second negative electrode active material accounts for 7-15%, the first conductive agent accounts for 0.5-1.5%, the second conductive agent accounts for 0.5-1.5%, and the binder accounts for 1-3%.
9. The lithium-ion battery negative electrode sheet according to claim 8, wherein the particle diameter of the first negative electrode active material is smaller than the particle diameter of the second negative electrode active material, and the gram capacity of the first negative electrode active material is larger than the gram capacity of the second negative electrode active material.
CN202310043009.XA 2023-01-28 2023-01-28 Lithium ion battery negative plate Pending CN116053412A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116565211A (en) * 2023-07-10 2023-08-08 深圳海辰储能控制技术有限公司 Negative plate, energy storage device and electric equipment

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116565211A (en) * 2023-07-10 2023-08-08 深圳海辰储能控制技术有限公司 Negative plate, energy storage device and electric equipment
CN116565211B (en) * 2023-07-10 2023-09-26 深圳海辰储能控制技术有限公司 Negative plate, energy storage device and electric equipment

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