CN113793930B - Positive plate and lithium ion battery - Google Patents

Positive plate and lithium ion battery Download PDF

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CN113793930B
CN113793930B CN202111091459.3A CN202111091459A CN113793930B CN 113793930 B CN113793930 B CN 113793930B CN 202111091459 A CN202111091459 A CN 202111091459A CN 113793930 B CN113793930 B CN 113793930B
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active layer
lithium
particles
cobalt oxide
lithium cobaltate
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CN113793930A (en
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韦世超
彭冲
李俊义
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Zhuhai Cosmx Battery Co Ltd
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Zhuhai Cosmx Battery Co Ltd
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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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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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  • Manufacturing & Machinery (AREA)
  • Inorganic Chemistry (AREA)
  • Battery Electrode And Active Subsutance (AREA)
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Abstract

The embodiment of the invention provides a positive plate and a lithium ion battery, wherein the positive plate comprises: a first active layer, a second active layer, and a current collector, wherein the first active layer is disposed between the current collector and the second active layer, the first active layer includes first lithium cobaltate particles and second lithium cobaltate particles, and the particle size of the first lithium cobaltate particles is different from the particle size of the second lithium cobaltate particles; the second active layer includes third lithium cobalt oxide particles and fourth lithium cobalt oxide particles, the third lithium cobalt oxide particles having a particle size different from that of the fourth lithium cobalt oxide particles. According to the positive plate provided by the embodiment of the invention, the energy density of the battery is improved by arranging the lithium cobaltate particles with various different particle diameters in the first active layer and the second active layer, and the problem of uneven lithium removal of the positive plate in the prior art is solved.

Description

Positive plate and lithium ion battery
Technical Field
The present disclosure relates to lithium ion batteries, and particularly to a positive electrode sheet and a lithium ion battery.
Background
Along with the energy density requirement of lithium ion batteries, pole pieces with large surface density and large compaction are matched to become the development trend of the industry. However, the large-area-density pole piece has uneven lithium removal on the pole piece surface layer and the bottom layer due to the difference of lithium removal potentials of the pole piece surface layer and the bottom layer, so that the capacity retention rate is seriously deteriorated in the later period of battery circulation; and the electrolyte is lack of water jump in the later period of battery circulation under the condition that the wettability of the pole piece with the electrolyte is not high under the condition of large compaction density.
Disclosure of Invention
The positive plate and the lithium ion battery provided by the embodiment of the invention solve the problem of uneven lithium removal of the positive plate in the prior art.
In a first aspect, the present embodiment provides a positive electrode sheet, including: a first active layer, a second active layer, and a current collector, wherein the first active layer is disposed between the current collector and the second active layer, the first active layer includes first lithium cobaltate particles and second lithium cobaltate particles, and the particle size of the first lithium cobaltate particles is different from the particle size of the second lithium cobaltate particles; the second active layer includes third lithium cobalt oxide particles and fourth lithium cobalt oxide particles, the third lithium cobalt oxide particles having a particle size different from that of the fourth lithium cobalt oxide particles.
Optionally, the first active layer further comprises a conductive agent and a binder, the median particle diameter of the first lithium cobaltate particles is a1, the median particle diameter of the second lithium cobaltate particles is b1, and the compacted density of the first active layer is c1, then the relationship of a1, b1 and c1 is 14< b1/a1×c1<26;
the second active layer further comprises the conductive agent and the binder, the median particle diameter of the third lithium cobalt oxide particles is a2, the median particle diameter of the fourth lithium cobalt oxide particles is b2, the compacted density of the second active layer is c2, and then the relationship of a2, b2 and c2 is 22<b2/a2*c2<28, the particle diameter is um, and the compaction density is g/cm 3 。
Optionally, the particle size of the first lithium cobaltate particles is smaller than the particle size of the second lithium cobaltate particles, the number of the first lithium cobaltate particles is larger than the number of the second lithium cobaltate particles, and the ratio of the number of the first lithium cobaltate particles to the number of the second lithium cobaltate particles is in the range of 1-5.
Optionally, the particle size range of the first lithium cobaltate particles is 4um-5um, and the particle size range of the second lithium cobaltate particles is 20um-28um.
Optionally, the particle size of the third lithium cobaltate particles is smaller than the particle size of the fourth lithium cobaltate particles, the number of the third lithium cobaltate particles is smaller than the number of the fourth lithium cobaltate particles, and the ratio of the number of the third lithium cobaltate particles to the number of the fourth lithium cobaltate particles is in the range of 0.2-1.
Optionally, the particle size range of the third lithium cobaltate particles is 5um-6um, and the particle size range of the fourth lithium cobaltate particles is 28um-35um.
Optionally, the second active layer has a compaction density that is less than the compaction density of the first active layer.
Optionally, the thickness of the first active layer is greater than the thickness of the second active layer.
In a second aspect, an embodiment of the present invention further provides a lithium ion battery, including the positive electrode sheet according to the first aspect.
According to the positive plate provided by the embodiment of the invention, the energy density of the battery is improved and the wettability of the electrolyte of the battery is improved by arranging the lithium cobaltate particles with different particle diameters in the first active layer and the second active layer.
Drawings
Fig. 1 is a structural diagram of a positive plate according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.
Before discussing exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although a flowchart depicts steps as a sequential process, many of the steps may be implemented in parallel, concurrently, or with other steps. Furthermore, the order of the steps may be rearranged. The process may be terminated when its operations are completed, but may have additional steps not included in the figures. The processes may correspond to methods, functions, procedures, subroutines, and the like.
Furthermore, the terms "first," "second," and the like, may be used herein to describe various directions, acts, steps, or elements, etc., but these directions, acts, steps, or elements are not limited by these terms. These terms are only used to distinguish one direction, action, step or element from another direction, action, step or element. For example, the first speed difference may be referred to as a second speed difference, and similarly, the second speed difference may be referred to as the first speed difference, without departing from the scope of the present application. Both the first speed difference and the second speed difference are speed differences, but they are not the same speed difference. The terms "first," "second," and the like, are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
Referring to fig. 1, fig. 1 is a structural diagram of a positive electrode sheet according to an embodiment of the present invention, specifically, the positive electrode sheet includes a first active layer 3, a second active layer 2, and a current collector 4, where the first active layer 3 includes first lithium cobaltate particles and second lithium cobaltate particles, and the particle size of the first lithium cobaltate particles is different from that of the second lithium cobaltate particles; the second active layer 2 includes third lithium cobalt oxide particles and fourth lithium cobalt oxide particles, and the particle size of the third lithium cobalt oxide particles is different from that of the fourth lithium cobalt oxide particles. In this embodiment, the positive electrode sheet is disposed under the separator 1, specifically, the second active layer 2 is disposed between the first active layer 3 and the separator 1.
In this embodiment, the positive plate includes two active layers, where the first active layer 3 is close to the current collector 4, and the second active layer 2 is close to the separator 1, in the prior art, there is a potential difference between the surface layer and the bottom layer in the positive plate, where the surface layer potential of the positive electrode is higher, the delithiation amount of the surface layer positive electrode material is larger, resulting in uneven delithiation of the positive electrode material in the circulation process, so that particle breakage is more serious, and the circulation performance is deteriorated. Accordingly, in the present embodiment, a plurality of lithium cobaltate particles having different particle diameters are provided in the first active layer 3 and the second active layer 2, and lithium cobaltate is an inorganic compound having a chemical formula of LiCoO 2 Lithium cobaltate has the advantages of excellent electrochemical performance, excellent processing performance, large tap density (which is helpful for improving the volume specific capacity of the battery), good stability and the like, and is generally used as a positive electrode material of a lithium ion battery. Specifically, by controlling the arrangement of a larger proportion of small-particle lithium cobalt oxide particles in the first active layer 3, the uniformity of the lithium removal amount of the first active layer 3 in the positive plate is improved, and simultaneously, by controlling the thickness of the second active layer 2 to be smaller than that of the first active layer 3, the quantity of the small-particle lithium cobalt oxide is ensured to be more,the compaction density of the battery is improved, and the energy density of the battery is improved. Aiming at the problem of lower porosity of the positive plate in the prior art, the size and size ratios of various lithium cobaltate particles are matched, specifically, large-particle lithium cobaltate particles are arranged in the second active layer 2, so that the positive plate is pressed by a roller with the same pressure, the second active layer 2 has smaller compaction density, the porosity of the second active layer 2 plate is improved, and the wettability of the plate and electrolyte is improved.
Optionally, the first active layer 3 further includes a conductive agent and a binder, the median particle diameter of the first lithium cobalt oxide particles is a1, the median particle diameter of the second lithium cobalt oxide particles is b1, the compacted density of the first active layer 3 is c1, and then the relationship among a1, b1 and c1 is 14<b1/a1*c1<26; the second active layer 2 further comprises the conductive agent and the binder, the median particle diameter of the third lithium cobalt oxide particles is a2, the median particle diameter of the fourth lithium cobalt oxide particles is b2, the compacted density of the second active layer 2 is c2, and then the relationship among a2, b2 and c2 is 22<b2/a2*c2<28, the particle diameter is um, and the compaction density is g/cm 3 。
In this embodiment, the positive electrode slurry is composed of active materials, specifically, the composition of the first active layer 3 includes 97.8% of small-particle lithium cobalt oxide (composed of first lithium cobalt oxide particles and second lithium cobalt oxide particles), 1.1% of a conductive agent and 1.1% of a binder, wherein the conductive agent is composed of a conductive carbon black and a conductive carbon tube mixed in a mass ratio of 4:1, and the conductive carbon black is carbon black having low resistance or high resistance properties. Can impart electrical conductivity or antistatic effect to the article. It features small particle size, large specific surface area, coarse structure, clean surface (less compound), etc. The conductive carbon tube is a one-dimensional quantum material with a special structure (the radial dimension is in the order of nanometers, the axial dimension is in the order of micrometers, and both ends of the tube are basically sealed). Carbon nanotubes mainly consist of layers to tens of layers of coaxial round tubes of carbon atoms arranged in a hexagonal manner. The layer-to-layer distance is kept constant, about 0.34nm, and the diameter is typically 2-20 nm. And the carbon hexagons can be divided into three types of zigzag, armchair and spiral according to different orientations of the carbon hexagons along the axial direction. The binder is polyvinylidene fluoride (vinylidene fluoride, PVDF), and the polyvinylidene fluoride mainly refers to vinylidene fluoride homopolymer or copolymer of vinylidene fluoride and other small amount of fluorine-containing vinyl monomers, has the characteristics of fluororesin and general resin, and has the special properties of good chemical corrosion resistance, high temperature resistance, oxidation resistance, weather resistance, radiation resistance, piezoelectricity, dielectric property, thermoelectric property and the like. The composition of the second active layer 2 comprises 97.8% of small-particle lithium cobalt oxide (composed of third lithium cobalt oxide particles and fourth lithium cobalt oxide particles), 1.1% of a conductive agent and 1.1% of a binder, wherein the conductive agent is formed by mixing conductive carbon black and conductive carbon tubes according to a mass ratio of 4:1, and the binder is polyvinylidene fluoride.
Optionally, the particle size of the first lithium cobaltate particles is smaller than the particle size of the second lithium cobaltate particles, and the number of the first lithium cobaltate particles is larger than the number of the second lithium cobaltate particles.
In this embodiment, the first active layer 3 adjacent to the current collector 4 contains two kinds of lithium cobaltate particles with different particle sizes, specifically, the particle size d=a1 of the first lithium cobaltate particles and the particle size d=b1 of the second lithium cobaltate particles, wherein the ratio of the number of the first lithium cobaltate particles to the number of the second lithium cobaltate particles is between 1 and 5. Specifically, the lithium cobaltate in the first active layer 3 is small-particle lithium cobaltate, the particle size range of the first lithium cobaltate particle is 4um-5um, and the particle size range of the second lithium cobaltate particle is 20um-28um. The particle size ranges of the first lithium cobaltate particles and the second lithium cobaltate particles in the embodiment are both preferred, and can be adaptively adjusted according to practical situations, and are not limited in the alternative of the embodiment.
Optionally, the particle size of the third lithium cobaltate particles is smaller than the particle size of the fourth lithium cobaltate particles, and the number of the third lithium cobaltate particles is smaller than the number of the fourth lithium cobaltate particles.
In the present embodiment, the second active layer 2 adjacent to the separator 1 contains two kinds of lithium cobaltate particles having different particle diameters, specifically, the particle diameter d=a2 of the third lithium cobaltate particles and the particle diameter d=b2 of the fourth lithium cobaltate particles, wherein the ratio of the number of the third lithium cobaltate particles to the number of the fourth lithium cobaltate particles is between 0.2 and 1. Specifically, the lithium cobaltate in the second active layer 2 is large-particle lithium cobaltate, the particle size range of the third lithium cobaltate particle is 5um-6um, and the particle size range of the fourth lithium cobaltate particle is 28um-35um. The particle size ranges of the third lithium cobaltate particles and the fourth lithium cobaltate particles in the embodiment are both preferred, and can be adaptively adjusted according to practical situations, and are not limited in the alternative of the embodiment.
Optionally, the compacted density of the second active layer 2 is greater than the compacted density of the first active layer 3.
In the present embodiment, the compacted density is that of the lithium battery at half-power, and in general, the compacted density of the first active layer 3 is 3.5 to 3.8g/cm 3 The second active layer has a compacted density of 3.7-4.1g/cm 3 The porosity in the pole piece is improved, and the wettability of the pole piece and electrolyte is improved.
Optionally, the thickness of the first active layer 3 is smaller than the thickness of the second active layer 2.
In this embodiment, in order to ensure that the battery energy density is compatible, the thickness of the pole piece of the first active layer 3 is set smaller than that of the pole piece of the second active layer 2, and the specific thickness is not specifically limited in this embodiment, and can be adjusted adaptively according to practical situations.
In this embodiment, the negative electrode sheet is generally formed by using a conventional negative electrode formulation, and the slurry is composed of an active material, a conductive agent, a binder, and a dispersing agent. The negative electrode active material is mainly graphite, and at least one of soft carbon, hard carbon and silicon-based material. Wherein, the dispersing agent is a surfactant with both opposite properties of lipophilicity and hydrophilicity in molecules. The solid and liquid particles of inorganic and organic pigments which are difficult to dissolve in liquid can be uniformly dispersed, and the sedimentation and agglomeration of the particles can be prevented to form the amphiphilic agent required for stable suspension.
Wherein the dispersing agent is a dispersing agent containing lithium salt, and the content of lithium ions is between 2.0 and 3.5 percent. The conductive agent is used for ensuring good charge and discharge performance of the electrode, a certain amount of conductive substances are generally added during the manufacture of the electrode plate, and micro-current collection is performed between active substances and between the active substances and the current collector 4, so that the contact resistance of the electrode is reduced to accelerate the movement rate of electrons, and meanwhile, the migration rate of lithium ions in the electrode material is effectively improved, so that the charge and discharge efficiency of the electrode is improved. The conductive agent material can be at least one of conductive carbon black, acetylene black, ketjen black, conductive graphite, conductive carbon fiber, carbon nanotube, metal powder and carbon fiber. The binder is a guarantee of the bond strength between the abrasive and the matrix. Along with the development of the chemical industry, various novel adhesives enter the field of coated abrasives, so that the performance of the coated abrasives is improved, and the development of the coated abrasives industry is promoted.
Besides sizing materials, the adhesive also comprises auxiliary components such as a solvent, a curing agent, a toughening agent, a preservative, a colorant, a defoaming agent and the like. The binders include synthetic resins, rubbers and paints, in addition to the most commonly used animal glues. Specifically, the content of the active substance is 97.5%, the conductive agent is formed by mixing conductive carbon tubes and conductive carbon black according to the proportion of 0.25-0.5%, the content of the conductive agent is 0.5%, the content of the binder is 1%, and the content of the dispersing agent is 1%.
In this embodiment, after the coating is completed, other processes are the same as those of the conventional lithium battery technology, and the soft-package polymer lithium ion battery is supported according to the normal processes of rolling, winding, packaging, liquid injection, formation, sorting and the like. Specifically, the coating mode described in the present invention may be prepared by extrusion coating or transfer coating, and an exemplary process of extrusion coating is to extrude one or more layers of coating liquid under pressure from the gap of the extrusion nozzle (some of the coating liquid flows through an inclined plane), form a meniscus between the lips and the substrate to be coated, and transfer the meniscus to a running support to form a thin layer. After the coating of the positive electrode and the negative electrode of the lithium battery is finished by adopting the method, rolling is carried out according to the process design to determine that the compaction density of the positive electrode and the negative electrode meets the process requirement, then sheet making (welding electrode lugs) and winding (positive electrode, diaphragm and negative electrode) are carried out, and the diaphragm adopts an Xuehua 5+2+2 oil-based diaphragm; and then packaging, injecting liquid and forming, then performing secondary packaging, and finally sorting to finish the manufacturing of the soft package polymer lithium ion battery, and then performing a report test.
According to the positive plate provided by the embodiment of the invention, the energy density of the battery is improved by arranging the lithium cobaltate particles with various different particle diameters in the first active layer and the second active layer, and the problems of uneven lithium removal and poor wettability of the battery electrolyte of the positive plate in the prior art are solved.
The results of preparing the positive electrode sheet in various ways are described in detail below by means of specific examples and comparative examples.
In comparative example 1, a conventional positive and negative electrode sheet was prepared by the above method, wherein the first and second active layers were coated with a slurry composed of a small particle lithium cobalt oxide material (small particle lithium cobalt oxide 97.8%, conductive agent 1.1%, binder 1.1%, conductive agent was a mixture of conductive carbon black and conductive carbon tube in a ratio of 4:1, binder was PVDF), wherein the first lithium cobalt oxide particle size d=4.5 um, the second lithium cobalt oxide particle size d=25 um, and the compacted density was 3.9g/cm 3 。
In comparative example 2, conventional positive and negative electrode sheets were prepared by the above method, wherein the first and second active layers were coated with slurry composed of large particle lithium cobalt oxide material (large particle lithium cobalt oxide 97.8%, conductive agent 1.1%, binder 1.1%, conductive agent composed of conductive carbon black and conductive carbon tube mixed in a ratio of 4:1, binder was PVDF), wherein the first lithium cobalt oxide particle size d=5.5 um, the second lithium cobalt oxide particle size d=29 um, and the compacted density was 3.5g/cm 3 。
In example 1, a conventional negative electrode sheet was prepared by the above method, and the positive electrode slurry was prepared in the manner described above to obtain a first active layer slurry (small particle lithium cobaltate 97.8%, conductive agent 1.1%, binder 1.1%, conductive agent was a mixture of conductive carbon black and conductive carbon tube in a ratio of 4:1, binder was PVDF) and a second active layer slurry (large particle lithium cobaltate 97.8%, conductive agent 1.1%, binder 1.1%, conductive agent was a mixture of conductive carbon black and conductive carbon tube in a ratio of 4:1, binder was PVDF). Sequentially coating a first active layer slurry and a second active layer slurry on a current collectorWherein the thickness of the first active layer and the second active layer is 6:4, the first lithium cobaltate D=4.5 um of the first active layer lithium cobaltate, the second lithium cobaltate particle diameter D=25 um, and the compaction density is 4.1g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the In the second active layer, the particle diameter D=5.5 um of the third lithium cobalt oxide, the particle diameter D=29 um of the fourth lithium cobalt oxide, and the compaction density is 3.5g/cm 3 。
In example 2, the difference between this example and example 1 is that the first active layer slurry and the second active layer slurry are sequentially coated on the current collector, wherein the thickness of the first active layer and the second active layer is 7:3, the first active layer lithium cobalt oxide has a first lithium cobalt oxide d=4.5 um, the second lithium cobalt oxide has a particle diameter d=25 um, and the compacted density is 4.0g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the In the second active layer, the particle diameter D=5.5 um of the third lithium cobalt oxide, the particle diameter D=29 um of the fourth lithium cobalt oxide, and the compaction density is 3.6g/cm 3 。
In example 3, the difference between this example and example 1 is that the first active layer slurry and the second active layer slurry are sequentially coated on the current collector, wherein the thickness of the first active layer and the second active layer is 8:2, the first active layer lithium cobalt oxide has a first lithium cobalt oxide d=4.5 um, the second lithium cobalt oxide has a particle diameter d=25 um, and the compacted density is 3.9g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the In the second active layer, the particle diameter D=5.5 um of the third lithium cobalt oxide, the particle diameter D=29 um of the fourth lithium cobalt oxide, and the compaction density is 3.7g/cm 3 。
As shown in table 1, in the above comparative examples and examples, by using the differential coating method of comparative example 1 and examples 1, 2 and 3, the lithium intercalation uniformity of the battery can be improved, the liquid retention amount of the battery can be improved, and the cycle performance of the battery can be improved. The large-particle lithium cobaltate is adopted in the comparative example 2, and the energy density is obviously lost although the large-particle lithium cobaltate has excellent performance, and the aim of combining the energy density and the cycle performance can be achieved by adopting the differentiated coating mode.
Regarding the energy density, the lithium ion batteries of examples and comparative examples were measured at 25 ℃ using a charge-discharge regime of 0.2C charge, 0.5C discharge, and 0.025C cutoff; the plateau voltage of the lithium ion battery is the plateau voltage under 0.2C rate discharge. Energy Density (ED) ED = capacity x plateau voltage/(cell length x cell width x cell thickness), 45 ℃ cyclic capacity retention and cyclic expansion were calculated using the following formula. The lithium ion batteries of the examples and the comparative examples were cycled for 600T at 45 ℃ with a cycling regime of 1C charge, 0.5C discharge, 0.025C cutoff; capacity retention = discharge capacity (per turn)/initial capacity; cyclic expansion ratio= (thickness after cycle-initial thickness)/initial thickness.
Figure BDA0003267656850000081
TABLE 1
The embodiment of the invention also provides a lithium ion battery, which comprises the positive plate in the embodiment. Because the technical solution of the present embodiment includes all the technical solutions of the foregoing embodiments, at least all the technical effects of the foregoing embodiments can be achieved, which is not described herein in detail.
The above is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the present invention, and it should be covered in the scope of the present invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.

Claims (9)

1. A positive electrode sheet, comprising: the lithium cobalt oxide collector comprises a first active layer, a second active layer and a current collector, wherein the first active layer is arranged between the current collector and the second active layer, the first active layer comprises first lithium cobalt oxide particles and second lithium cobalt oxide particles, and the particle size of the first lithium cobalt oxide particles is smaller than that of the second lithium cobalt oxide particles; the second active layer comprises third lithium cobalt oxide particles and fourth lithium cobalt oxide particles, wherein the particle size of the third lithium cobalt oxide particles is smaller than that of the fourth lithium cobalt oxide particles;
the first active layer further comprises a conductive agent and a binder, wherein the median particle diameter of the first lithium cobaltate particles is a1, the median particle diameter of the second lithium cobaltate particles is b1, the compaction density of the first active layer is c1, and then the relationship of a1, b1 and c1 is 14< b1/a 1c 1<26;
the second active layer further comprises the conductive agent and the binder, the median particle diameter of the third lithium cobalt oxide particles is a2, the median particle diameter of the fourth lithium cobalt oxide particles is b2, the compacted density of the second active layer is c2, and then the relationship of a2, b2 and c2 is 22<b2/a2*c2<28, the particle diameter is um, and the compaction density is g/cm 3 。
2. The positive electrode sheet according to claim 1, wherein the number of the first lithium cobaltate particles is larger than the number of the second lithium cobaltate particles, and a ratio of the number of the first lithium cobaltate particles to the number of the second lithium cobaltate particles is in a range of 1 to 5.
3. The positive electrode sheet according to claim 2, wherein the first lithium cobaltate particles have a particle size ranging from 4um to 5um, and the second lithium cobaltate particles have a particle size ranging from 20um to 28um.
4. The positive electrode sheet according to claim 1, wherein the number of the third lithium cobaltate particles is smaller than the number of the fourth lithium cobaltate particles, and a ratio of the number of the third lithium cobaltate particles to the number of the fourth lithium cobaltate particles is in a range of 0.2 to 1.
5. The positive electrode sheet according to claim 2, wherein the particle diameter of the third lithium cobaltate particles is in the range of 5um to 6um, and the particle diameter of the fourth lithium cobaltate particles is in the range of 28um to 35um.
6. The positive electrode sheet of claim 1, wherein the compacted density of the second active layer is less than the compacted density of the first active layer.
7. The positive electrode sheet according to claim 1, wherein the second active layer has a porosity greater than that of the first active layer.
8. The positive electrode sheet according to claim 1, wherein the thickness of the first active layer is smaller than the thickness of the second active layer.
9. A lithium ion battery comprising the positive electrode sheet according to any one of claims 1 to 8.
CN202111091459.3A 2021-09-17 2021-09-17 Positive plate and lithium ion battery Active CN113793930B (en)

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110970613A (en) * 2018-09-29 2020-04-07 宁德时代新能源科技股份有限公司 Positive pole piece and lithium ion battery using same

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110970613A (en) * 2018-09-29 2020-04-07 宁德时代新能源科技股份有限公司 Positive pole piece and lithium ion battery using same

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