CN113130907A - Battery cell, preparation method thereof and fast-charging lithium ion battery - Google Patents
Battery cell, preparation method thereof and fast-charging lithium ion battery Download PDFInfo
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- CN113130907A CN113130907A CN202110417907.8A CN202110417907A CN113130907A CN 113130907 A CN113130907 A CN 113130907A CN 202110417907 A CN202110417907 A CN 202110417907A CN 113130907 A CN113130907 A CN 113130907A
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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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
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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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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- 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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- 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
Abstract
The invention discloses a battery cell, a preparation method thereof and a fast-charging lithium ion battery, wherein the battery cell comprises a positive plate, a negative plate and a diaphragm arranged between the positive plate and the negative plate; the positive plate comprises a positive current collector and a positive active material layer arranged on the positive current collector, the material of the positive active material layer comprises a positive active material, a positive conductive agent and a positive binder, and the positive conductive agent comprises a first point-shaped conductive agent and a first branch-chain-shaped conductive agent; the negative plate comprises a negative current collector and a negative active material layer arranged on the negative current collector, the negative active material layer comprises a negative active material, a negative conductive agent, a dispersing agent and a negative binder, the negative conductive agent comprises a second point conductive agent and a second branched chain conductive agent, and the dispersing agent is carboxymethyl cellulose lithium. The battery cell can be applied to the preparation of the quick-charging lithium ion battery, and the prepared quick-charging lithium ion battery has excellent quick-charging performance and long cycle life.
Description
Technical Field
The invention relates to the technical field of battery manufacturing, in particular to a battery cell, a preparation method thereof and a quick-charging lithium ion battery.
Background
The lithium ion battery has the advantages of high energy density, good cycle performance, no memory effect and the like, and is widely applied to the fields of mobile phones, computers, electric tools, new energy automobiles and energy storage, but the long charging time of the lithium ion battery is a core pain point of consumers. If the battery can realize quick charge, the user can not be anxious for the electric quantity any more, and electric automobile can replace traditional fuel vehicle better, and quick energy storage equipment can undertake more complicated service functions in the electric wire netting, and its quick response makes it can participate in the intelligent regulation of electric wire netting, and this will bring very big facility and comprehensive benefit for people's life. Therefore, the development and application of the fast-charging lithium ion battery have become urgent needs for the development of the lithium ion battery.
However, the conventional lithium ion battery is subject to many problems, such as severe polarization and heat generation during large current charging, and increased side reactions, and when the large current charging is performed, part of lithium ions cannot be inserted into the negative electrode in time to cause lithium precipitation of the negative electrode, which further causes capacity attenuation and potential safety hazard. Therefore, to realize the quick charge of the lithium ion battery, the related performance of the lithium ion battery is also improved correspondingly.
At present, some researchers have proposed some fast-charging lithium ion batteries, and attempt to improve the performance of the fast-charging lithium ion batteries by some modifications to reduce battery impedance, reduce polarization, and the like. However, in the existing research of the fast-charging lithium ion battery, the performance requirements such as long cycle life and the like are difficult to achieve while the fast charging is realized.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a battery cell, a preparation method thereof and a fast-charging lithium ion battery.
In a first aspect of the present invention, a battery cell is provided, including:
the positive plate comprises a positive current collector and a positive active material layer arranged on the positive current collector, and the material of the positive active material layer comprises a positive active material, a positive conductive agent and a positive binder; the positive electrode conductive agent comprises a first point-shaped conductive agent and a first branched chain-shaped conductive agent;
the negative plate comprises a negative current collector and a negative active material layer arranged on the negative current collector, wherein the negative active material layer comprises a negative active material, a negative conductive agent, a dispersing agent and a negative binder; the negative electrode conductive agent comprises a second point conductive agent and a second branched chain conductive agent, and the dispersing agent is selected from carboxymethyl cellulose lithium;
and the diaphragm is arranged between the positive plate and the negative plate.
The battery cell provided by the embodiment of the invention at least has the following beneficial effects: the battery cell can be used for preparing a quick lithium ion battery, wherein a conductive agent in an active material layer on a positive plate and a negative plate is formed by mixing components including a point conductive agent and a branched chain conductive agent, the mixed conductive agent can construct a three-dimensional conductive network structure, and the three-dimensional conductive network structure is connected with the active material through points and lines, so that a high-speed channel can be provided for the transmission of ions and electrons in the electrochemical reaction process, the ionic conductivity is improved, and the quick charging performance of the battery is improved; in addition, certain inhibition effect on the volume expansion of the negative electrode can be achieved in the charging process, and the cycle stability of the quick-charging lithium ion battery is improved. In addition, the dispersant in the negative active material layer on the negative plate adopts carboxymethyl cellulose lithium to replace the traditional dispersant sodium carboxymethyl cellulose, and the carboxymethyl cellulose lithium can not only increase the conductivity of the negative electrode, but also improve the transmission rate of lithium ions in the electrode, so as to avoid the phenomenon that the lithium ions cannot be inserted into the negative electrode in time of quick charging and cause the lithium precipitation of the negative electrode. By the improvement of the conductive agent in the active material layer on the positive plate and the negative plate of the battery cell and the improvement of the dispersing agent in the negative active material layer on the negative plate, the impedance and polarization phenomena of the battery can be obviously reduced, and the prepared fast-charging lithium ion battery can have excellent charging rate performance.
The term "midpoint state" in the first dot-like conductive agent and the second dot-like conductive agent means specifically a particulate state, and the second dot-like conductive agent and the second branched-chain conductive agent may be tubular and/or rod-like.
In some embodiments of the present invention, the first dot-shaped conductive agent and the second dot-shaped conductive agent are selected from conductive carbon black, the first branched-chain-shaped conductive agent is selected from at least one of ketjen black, multi-walled carbon nanotubes, and carbon nanofibers, and the second branched-chain-shaped conductive agent is selected from at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon nanofibers. If the single-walled carbon nanotube is used as a conductive agent for preparing the negative plate, a three-dimensional conductive network is constructed, and meanwhile, the negative expansion can be inhibited, so that the cycle performance of the battery can be remarkably improved; however, the cost of the single-walled carbon nanotube is high, if the single-walled carbon nanotube is used for preparing the positive plate, the single-walled carbon nanotube is difficult to disperse in positive slurry, the positive electrode has small expansion in the use process of the battery, and the addition of the single-walled carbon nanotube in the positive electrode has no obvious cycle improvement, so that compared with the single-walled carbon nanotube, the multi-walled carbon nanotube which is easy to disperse is more adopted in the positive active material layer of the positive plate.
In some embodiments of the invention, the composition of the positive electrode conductive agent further comprises a lamellar conductive agent; preferably, the sheet-like conductive agent is selected from graphene.
In some embodiments of the invention, the composition of the positive electrode conductive agent includes the first point-like conductive agent, the first branch-chain-like conductive agent, and the sheet-like conductive agent in a mass ratio of 4:2: 1; the negative electrode conductive agent comprises the following components in percentage by mass: 1 and a second branched conductive agent.
In some embodiments of the present invention, the material of the positive electrode active material layer includes 93 wt% to 97 wt% of a positive electrode active material, 0.5 wt% to 3 wt% of a positive electrode conductive agent, and 1 wt% to 4 wt% of a positive electrode binder; the material of the negative active material layer comprises 93-97 wt% of negative active material, 0.5-2 wt% of negative conductive agent, 0.5-2 wt% of dispersant and 0.5-3 wt% of negative binder.
In some embodiments of the present invention, the positive active material is selected from nickel cobalt manganese ternary materials, preferably nickel cobalt manganese ternary materials with a nickel content of 50% to 85%; the positive electrode binder is selected from polyvinylidene fluoride; the negative electrode active material is selected from graphite, and the negative electrode binder is selected from at least one of styrene-butadiene rubber and polyacrylic acid glue
In some embodiments of the invention, the positive current collector is selected from aluminum foil and the negative current collector is selected from copper foil.
In a second aspect of the present invention, a method for manufacturing any one of the battery cells proposed in the first aspect of the present invention is provided, including the following steps:
mixing the material of the positive electrode active material layer with a first solvent to prepare positive electrode slurry; coating the positive electrode slurry on the surface of a positive electrode current collector, drying, rolling and die cutting to obtain a positive plate;
mixing the material of the negative electrode active material layer with a second solvent to prepare negative electrode slurry; coating the negative electrode slurry on the surface of a negative electrode current collector, drying, rolling and die cutting to prepare a negative electrode sheet;
and arranging a diaphragm between the positive plate and the negative plate to obtain the battery core.
In some embodiments of the invention, the first solvent is N-methylpyrrolidone and the second solvent is deionized water.
In a second aspect of the present invention, a fast-charging lithium ion battery is provided, which includes any one of the battery cells provided in the first aspect of the present invention. The fast-charging lithium ion battery specifically comprises a shell, and a battery cell and electrolyte accommodated in the shell.
Drawings
The invention is further described with reference to the following figures and examples, in which:
fig. 1 is a cycle plot of a fast-charging lithium ion battery C1# made using the battery cells of example 1;
fig. 2 is a cycle plot of a fast-charging lithium ion battery C2# made using the battery cells of example 2;
fig. 3 is a cycle curve diagram of a fast-charging lithium ion battery C3# made using the battery cells of example 3;
fig. 4 is a comparative graph of cycle curves of fast-charging lithium ion batteries C1# and C4# fabricated by using the battery cells of examples 1 and 4, respectively;
fig. 5 is a comparative plot of the cycling curves for the fast-charging li-ion batteries C1# and C5# made using the battery cells of example 1 and comparative example 1, respectively;
fig. 6 is a comparative plot of the cycling curves for the fast-charging li-ion batteries C2# and C6# made using the battery cells of example 2 and comparative example 2, respectively;
fig. 7 is a comparative plot of the cycling curves for the fast-charging li-ion batteries C1# and C7# made using the battery cells of example 1 and comparative example 3, respectively;
fig. 8 is a graph comparing the cycling curves of fast-charging li-ion batteries C2# and C8# made using the battery cells of example 2 and comparative example 4, respectively.
Detailed Description
The concept and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments to fully understand the objects, features and effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention.
Example 1
The embodiment prepares a battery cell, and the specific process comprises the following steps:
s1, weighing a positive electrode active material, a positive electrode conductive agent and a positive electrode binder according to a mass ratio of 96.5:2.5:1, wherein the positive electrode active material is a nickel-cobalt-manganese ternary material, the positive electrode conductive agent consists of point conductive agent conductive carbon black, a branched chain conductive agent multiwall carbon nanotube and a lamellar conductive agent graphene according to a mass ratio of 4:2:1, and the positive electrode binder is polyvinylidene fluoride;
s2, adding the positive active material, the conductive carbon black and the polyvinylidene fluoride into a slurry mixing pot, stirring for 20min at a stirring speed of revolution 30rpm, then adding an N-methyl pyrrolidone (NMP) solution of the positive active material mass 1/5, and stirring for 30min at a stirring speed of revolution 30 rpm; then adding the multi-walled carbon nanotube and the graphene slurry, stirring for 10min at the revolution speed of 30rpm, vacuumizing (the vacuum degree is less than or equal to-0.08 MPa), and stirring for 180min at the revolution speed of 30rpm and the rotation speed of 2000 rpm; after stirring, sieving the slurry by a 150-mesh sieve to prepare anode slurry for later use;
s3, weighing a negative electrode active material, a negative electrode conductive agent, a dispersing agent and a negative electrode binder according to a mass ratio of 95.5:1:1.5:2, wherein the negative electrode active material is graphite, the negative electrode conductive agent is composed of a dotted conductive agent conductive carbon black and a branched conductive agent single-walled carbon nanotube according to a mass ratio of 2:1, the dispersing agent is lithium carboxymethyl cellulose, and the negative electrode binder is styrene butadiene rubber emulsion;
s4, adding the negative electrode active material, the conductive carbon black and the lithium carboxymethyl cellulose into a slurry mixing pot, stirring for 20min at a stirring speed of revolution 25rpm, then adding deionized water with the mass of 1/3 of the negative electrode active material, stirring for 10min at a stirring speed of revolution 25rpm, and stirring for 120min at a stirring speed of revolution 25rpm and rotation 1500 rpm; then adding single-walled carbon nanotube slurry, vacuumizing (the vacuum degree is less than or equal to-0.08 MPa), and then stirring for 120min at revolution speed of 25rpm and rotation speed of 2000 rpm; adding styrene-butadiene rubber emulsion, vacuumizing (vacuum degree is less than or equal to-0.08 MPa), and stirring at revolution speed of 20rpm for 30 min; after stirring, sieving the slurry with a 150-mesh sieve to prepare cathode slurry for later use;
s5, coating the positive electrode slurry prepared in the step S2 on two surfaces of an aluminum foil of a positive electrode current collector, wherein the single-side surface density is 16mg/cm2Rolling to 105 μm, forming a positive active material layer on the positive current collector, and die-cutting to obtain a positive plate; coating the negative electrode slurry obtained in the step S4 on two surfaces of the copper foil of the negative electrode current collector, wherein the single-side surface density is 9.5mg/cm2Rolling to 128 mu m, forming a negative active material layer on a negative current collector, and die-cutting to obtain a negative plate;
and S6, stacking the positive plate and the negative plate obtained in the step 5 with a diaphragm, wherein the diaphragm is arranged between the positive plate and the negative plate, and thus obtaining the battery cell.
The battery cell prepared by the method comprises a positive plate, a negative plate and a diaphragm arranged between the positive plate and the negative plate; the positive plate comprises a positive current collector aluminum foil and a positive active material layer arranged on the positive current collector aluminum foil, the positive active material layer comprises a positive active material nickel-cobalt-manganese ternary material, a positive conductive agent and positive binder polyvinylidene fluoride in a mass ratio of 96.5:2.5:1, and the positive conductive agent comprises point conductive agent conductive carbon black, a branched chain conductive agent multiwall carbon nanotube and lamellar conductive agent graphene in a mass ratio of 4:2: 1; the negative plate comprises a negative current collector copper foil and a negative active material layer arranged on the negative current collector, the negative active material layer comprises negative active material graphite, a negative conductive agent, a dispersing agent carboxymethyl cellulose lithium and negative binder styrene butadiene rubber in a mass ratio of 95.5:1:1.5:2, and the negative conductive agent comprises point conductive agent conductive carbon black and a branched chain conductive agent single-walled carbon nanotube in a mass ratio of 2: 1.
Example 2
The embodiment prepares a battery cell, and the specific process comprises the following steps:
s1, weighing a positive electrode active material, a positive electrode conductive agent and a positive electrode binder according to a mass ratio of 96:3:1, wherein the positive electrode active material is a nickel-cobalt-manganese ternary material, the positive electrode conductive agent is composed of point conductive agent conductive carbon black, branched chain conductive agent carbon nanofiber and sheet layered conductive agent graphene according to a mass ratio of 4:2:1, and the positive electrode binder is polyvinylidene fluoride;
s2, adding the positive active material, the conductive carbon black and the polyvinylidene fluoride into a slurry mixing pot, stirring for 20min at a stirring speed of revolution 30rpm, then adding an NMP solution with the mass of the positive active material of 1/5, and stirring for 30min at a stirring speed of revolution 30 rpm; adding carbon nanofiber and graphene slurry, stirring at the revolution speed of 30rpm for 10min, vacuumizing (the vacuum degree is less than or equal to-0.08 MPa), and stirring at the revolution speed of 30rpm and the rotation speed of 2000rpm for 180 min; after stirring, sieving the slurry by a 150-mesh sieve to prepare anode slurry for later use;
s3, weighing a negative electrode active material, a negative electrode conductive agent, a dispersing agent and a negative electrode binder according to a mass ratio of 95:1.5:1.5:2, wherein the negative electrode active material is graphite, the negative electrode conductive agent is composed of a dot conductive agent conductive carbon black and a branched chain conductive agent carbon nanofiber according to a mass ratio of 2:1, the dispersing agent is lithium carboxymethyl cellulose, and the negative electrode binder is styrene-butadiene rubber emulsion;
s4, adding the negative electrode active material, the conductive carbon black and the lithium carboxymethyl cellulose into a slurry mixing pot, stirring for 20min at a stirring speed of revolution 25rpm, then adding deionized water with the mass of 1/3 of the negative electrode active material, stirring for 10min at a stirring speed of revolution 25rpm, and stirring for 120min at a stirring speed of revolution 25rpm and rotation 1500 rpm; then adding the carbon nanofiber slurry, vacuumizing (the vacuum degree is less than or equal to-0.08 MPa), and then stirring for 120min at revolution speed of 25rpm and rotation speed of 2000 rpm; adding styrene-butadiene rubber emulsion, vacuumizing (vacuum degree is less than or equal to-0.08 MPa), and stirring at revolution speed of 20rpm for 30 min; after stirring, sieving the slurry with a 150-mesh sieve to prepare cathode slurry for later use;
s5, coating the positive electrode slurry prepared in the step S2 on two surfaces of an aluminum foil of a positive electrode current collector, wherein the single-side surface density is 16mg/cm2Rolling to 105 μm, and die cutting to obtain a positive plate; coating the negative electrode slurry obtained in the step S4 on two surfaces of the copper foil of the negative electrode current collector, wherein the single-side surface density is 9.5mg/cm2Rolling to 128 mu m, and die cutting to obtain a negative plate;
and S6, stacking the positive plate and the negative plate obtained in the step 5 with a diaphragm, wherein the diaphragm is arranged between the positive plate and the negative plate, and thus obtaining the battery cell.
The battery cell prepared by the method comprises a positive plate, a negative plate and a diaphragm arranged between the positive plate and the negative plate; the positive plate comprises a positive current collector aluminum foil and a positive active material layer arranged on the positive current collector aluminum foil, the positive active material layer comprises a positive active material nickel-cobalt-manganese ternary material, a positive conductive agent and a positive binder polyvinylidene fluoride in a mass ratio of 96:3:1, and the positive conductive agent comprises point conductive agent conductive carbon black, branched conductive agent carbon nanofiber and plate-shaped conductive agent graphene in a mass ratio of 4:2: 1; the negative plate comprises a negative current collector copper foil and a negative active material layer arranged on the negative current collector, the negative active material layer comprises negative active material graphite, a negative conductive agent, a dispersing agent carboxymethyl cellulose lithium and negative binder styrene butadiene rubber in a mass ratio of 95:1.5:1.5:2, and the negative conductive agent comprises point conductive agent conductive carbon black and branched chain conductive agent carbon nanofiber in a mass ratio of 2: 1.
Example 3
The embodiment prepares a battery cell, and the specific process comprises the following steps:
s1, weighing a positive electrode active material, a positive electrode conductive agent and a positive electrode binder according to a mass ratio of 96.2:2.8:1, wherein the positive electrode active material is a nickel-cobalt-manganese ternary material, the positive electrode conductive agent consists of point conductive agent conductive carbon black, branched chain conductive agent Keqin black and lamellar conductive agent graphene according to a mass ratio of 4:2:1, and the positive electrode binder is polyvinylidene fluoride;
s2, adding the positive active material, the conductive carbon black, the Ketjen black and the polyvinylidene fluoride into a pulp mixing pot, stirring for 20min at a stirring speed of revolution 30rpm, then adding an NMP solution with the mass of 1/4 of the positive active material, and stirring for 30min at a stirring speed of revolution 30 rpm; adding graphene slurry, stirring at the revolution speed of 30rpm for 10min, vacuumizing (the vacuum degree is less than or equal to-0.08 MPa), and stirring at the revolution speed of 30rpm and the rotation speed of 2000rpm for 180 min; after stirring, sieving the slurry by a 150-mesh sieve to prepare anode slurry for later use;
s3, weighing a negative electrode active material, a negative electrode conductive agent, a dispersing agent and a negative electrode binder according to a mass ratio of 95:1.5:1.5:2, wherein the negative electrode active material is graphite, the negative electrode conductive agent is composed of a point conductive agent conductive carbon black and a branched chain conductive agent multi-walled carbon nanotube according to a mass ratio of 2:1, the dispersing agent is lithium carboxymethyl cellulose, and the negative electrode binder is styrene butadiene rubber emulsion;
s4, adding the negative electrode active material, the conductive carbon black and the lithium carboxymethyl cellulose into a slurry mixing pot, stirring for 20min at a stirring speed of revolution 25rpm, then adding deionized water with the mass of 1/3 of the negative electrode active material, stirring for 10min at a stirring speed of revolution 25rpm, and stirring for 120min at a stirring speed of revolution 25rpm and rotation 1500 rpm; then adding multi-wall carbon nano-tube slurry, vacuumizing (the vacuum degree is less than or equal to-0.08 MPa), and then stirring for 120min at revolution speed of 25rpm and rotation speed of 2000 rpm; adding styrene-butadiene rubber emulsion, vacuumizing (vacuum degree is less than or equal to-0.08 MPa), and stirring at revolution speed of 20rpm for 30 min; after stirring, sieving the slurry with a 150-mesh sieve to prepare cathode slurry for later use;
s5, coating the positive electrode slurry prepared in the step S2 on two surfaces of an aluminum foil of a positive electrode current collector, wherein the single-side surface density is 16mg/cm2Rolling to 105 μm, and die cutting to obtain a positive plate; coating the negative electrode slurry obtained in the step S4 on two surfaces of the copper foil of the negative electrode current collector, wherein the single-side surface density is 9.5mg/cm2Rolling to 128 mu m, and die cutting to obtain a negative plate;
and S6, stacking the positive plate and the negative plate obtained in the step 5 with a diaphragm, wherein the diaphragm is arranged between the positive plate and the negative plate, and thus obtaining the battery cell.
The battery cell prepared by the method comprises a positive plate, a negative plate and a diaphragm arranged between the positive plate and the negative plate; the positive plate comprises a positive current collector aluminum foil and a positive active material layer arranged on the positive current collector aluminum foil, the positive active material layer comprises a positive active material nickel-cobalt-manganese ternary material, a positive conductive agent and a positive binder polyvinylidene fluoride in a mass ratio of 96.2:2.8:1, and the positive conductive agent comprises point conductive agent conductive carbon black, branched chain conductive agent ketjen black and lamellar conductive agent graphene in a mass ratio of 4:2: 1; the negative plate comprises a negative current collector copper foil and a negative active material layer arranged on the negative current collector, the negative active material layer comprises negative active material graphite, a negative conductive agent, a dispersing agent carboxymethyl cellulose lithium and negative binder styrene butadiene rubber in a mass ratio of 95:1.5:1.5:2, and the negative conductive agent comprises point conductive agent conductive carbon black and a branched chain conductive agent multi-walled carbon nano tube in a mass ratio of 2: 1.
Example 4
The embodiment prepares a battery cell, and the specific process comprises the following steps:
s1, weighing a positive electrode active material, a positive electrode conductive agent and a positive electrode binder according to a mass ratio of 96.5:2.5:1, wherein the positive electrode active material is a nickel-cobalt-manganese ternary material, the positive electrode conductive agent is composed of point conductive agent conductive carbon black and a branched chain conductive agent multi-walled carbon nanotube according to a mass ratio of 2:1, and the positive electrode binder is polyvinylidene fluoride;
s2, adding the positive active material, the conductive carbon black and the polyvinylidene fluoride into a slurry mixing pot, stirring for 20min at a stirring speed of revolution 30rpm, then adding an NMP solution with the mass of the positive active material of 1/5, and stirring for 30min at a stirring speed of revolution 30 rpm; adding multi-wall carbon nanotube slurry, stirring at revolution speed of 30rpm for 10min, vacuumizing (vacuum degree is less than or equal to-0.08 MPa), and stirring at revolution speed of 30rpm and rotation speed of 2000rpm for 180 min; after stirring, sieving the slurry by a 150-mesh sieve to prepare anode slurry for later use;
s3, weighing a negative electrode active material, a negative electrode conductive agent, a dispersing agent and a negative electrode binder according to a mass ratio of 95.5:1:1.5:2, wherein the negative electrode active material is graphite, the negative electrode conductive agent is composed of a dotted conductive agent conductive carbon black and a branched conductive agent single-walled carbon nanotube according to a mass ratio of 2:1, the dispersing agent is lithium carboxymethyl cellulose, and the negative electrode binder is styrene butadiene rubber emulsion;
s4, adding the negative electrode active material, the conductive carbon black and the lithium carboxymethyl cellulose into a slurry mixing pot, stirring for 20min at a stirring speed of revolution 25rpm, then adding deionized water with the mass of 1/3 of the negative electrode active material, stirring for 10min at a stirring speed of revolution 25rpm, and stirring for 120min at a stirring speed of revolution 25rpm and rotation 1500 rpm; then adding single-walled carbon nanotube slurry, vacuumizing (the vacuum degree is less than or equal to-0.08 MPa), and then stirring for 120min at revolution speed of 25rpm and rotation speed of 2000 rpm; adding styrene-butadiene rubber emulsion, vacuumizing (vacuum degree is less than or equal to-0.08 MPa), and stirring at revolution speed of 20rpm for 30 min; after stirring, sieving the slurry with a 150-mesh sieve to prepare cathode slurry for later use;
s5, coating the positive electrode slurry prepared in the step S2 on two surfaces of an aluminum foil of a positive electrode current collector, wherein the single-side surface density is 16mg/cm2Rolling to 105 μm, and die cutting to obtain a positive plate; coating the negative electrode slurry obtained in the step S4 on two surfaces of the copper foil of the negative electrode current collector, wherein the single-side surface density is 9.5mg/cm2Rolling to 128 mu m, and die cutting to obtain a negative plate;
and S6, stacking the positive plate and the negative plate obtained in the step 5 with a diaphragm, wherein the diaphragm is arranged between the positive plate and the negative plate, and thus obtaining the battery cell.
The battery cell prepared by the method comprises a positive plate, a negative plate and a diaphragm arranged between the positive plate and the negative plate; the positive plate comprises a positive current collector aluminum foil and a positive active material layer arranged on the positive current collector aluminum foil, the positive active material layer comprises a positive active material nickel-cobalt-manganese ternary material, a positive conductive agent and positive binder polyvinylidene fluoride in a mass ratio of 96.5:2.5:1, and the positive conductive agent comprises point conductive agent conductive carbon black and a branched chain conductive agent multi-walled carbon nanotube in a mass ratio of 2: 1; the negative plate comprises a negative current collector copper foil and a negative active material layer arranged on the negative current collector, the negative active material layer comprises negative active material graphite, a negative conductive agent, a dispersing agent carboxymethyl cellulose lithium and negative binder styrene butadiene rubber in a mass ratio of 95.5:1:1.5:2, and the negative conductive agent comprises point conductive agent conductive carbon black and a branched chain conductive agent single-walled carbon nanotube in a mass ratio of 2: 1.
Comparative example 1
The comparative example prepared a battery cell, and the positive electrode slurry of the comparative example used a conventional conductive agent (conductive carbon black and graphene) as the positive electrode conductive agent. The specific preparation process comprises the following steps:
s1, weighing a positive electrode active material, a positive electrode conductive agent and a positive electrode binder according to a mass ratio of 96.5:2.5:1, wherein the positive electrode active material is a nickel-cobalt-manganese ternary material, the positive electrode conductive agent is composed of point conductive agent conductive carbon black and lamellar conductive agent graphene according to a mass ratio of 4:1, and the positive electrode binder is polyvinylidene fluoride;
s2, adding the positive active material, the conductive carbon black and the polyvinylidene fluoride into a slurry mixing pot, stirring for 20min at a stirring speed of revolution 30rpm, then adding an NMP solution with the mass of the positive active material of 1/5, and stirring for 30min at a stirring speed of revolution 30 rpm; adding graphene slurry, stirring at the revolution speed of 30rpm for 10min, vacuumizing (the vacuum degree is less than or equal to-0.08 MPa), and stirring at the revolution speed of 30rpm and the rotation speed of 2000rpm for 180 min; after stirring, sieving the slurry by a 150-mesh sieve to prepare anode slurry for later use;
s3, weighing a negative electrode active material, a negative electrode conductive agent, a dispersing agent and a negative electrode binder according to a mass ratio of 95.5:1:1.5:2, wherein the negative electrode active material is graphite, the negative electrode conductive agent is composed of a dotted conductive agent conductive carbon black and a branched conductive agent single-walled carbon nanotube according to a mass ratio of 2:1, the dispersing agent is lithium carboxymethyl cellulose, and the negative electrode binder is styrene butadiene rubber emulsion;
s4, adding the negative electrode active material, the conductive carbon black and the lithium carboxymethyl cellulose into a slurry mixing pot, stirring for 20min at a stirring speed of revolution 25rpm, then adding deionized water with the mass of 1/3 of the negative electrode active material, stirring for 10min at a stirring speed of revolution 25rpm, and stirring for 120min at a stirring speed of revolution 25rpm and rotation 1500 rpm; then adding single-walled carbon nanotube slurry, vacuumizing (the vacuum degree is less than or equal to-0.08 MPa), and then stirring for 120min at revolution speed of 25rpm and rotation speed of 2000 rpm; adding styrene-butadiene rubber emulsion, vacuumizing (vacuum degree is less than or equal to-0.08 MPa), and stirring at revolution speed of 20rpm for 30 min; after stirring, sieving the slurry with a 150-mesh sieve to prepare cathode slurry for later use;
s5, coating the positive electrode slurry prepared in the step S2 on two surfaces of an aluminum foil of a positive electrode current collector, wherein the single-side surface density is 16mg/cm2Rolling to 105 μm, and die cutting to obtain a positive plate; coating the negative electrode slurry obtained in the step S4 on two surfaces of the copper foil of the negative electrode current collector, wherein the single-side surface density is 9.5mg/cm2Rolling to 128 mu m, and die cutting to obtain a negative plate;
and S6, stacking the positive plate and the negative plate obtained in the step 5 with a diaphragm, wherein the diaphragm is arranged between the positive plate and the negative plate, and thus obtaining the battery cell.
The battery cell prepared by the method comprises a positive plate, a negative plate and a diaphragm arranged between the positive plate and the negative plate; the positive plate comprises a positive current collector aluminum foil and a positive active material layer arranged on the positive current collector aluminum foil, the positive active material layer comprises a positive active material nickel-cobalt-manganese ternary material, a positive conductive agent and positive binder polyvinylidene fluoride in a mass ratio of 96.5:2.5:1, and the positive conductive agent comprises point conductive agent conductive carbon black and lamellar conductive agent graphene in a mass ratio of 4: 1; the negative plate comprises a negative current collector copper foil and a negative active material layer arranged on the negative current collector, the negative active material layer comprises negative active material graphite, a negative conductive agent, a dispersing agent carboxymethyl cellulose lithium and negative binder styrene butadiene rubber in a mass ratio of 95.5:1:1.5:2, and the negative conductive agent comprises point conductive agent conductive carbon black and a branched chain conductive agent single-walled carbon nanotube in a mass ratio of 2: 1.
Comparative example 2
The comparative example is used for preparing a battery cell, and the cathode conductive agent in the cathode slurry of the comparative example is a conventional conductive agent (conductive carbon black), and the dispersing agent is carboxymethyl cellulose sodium which is a conventional dispersing agent. The specific preparation process comprises the following steps:
s1, weighing a positive electrode active material, a positive electrode conductive agent and a positive electrode binder according to a mass ratio of 96:3:1, wherein the positive electrode active material is a nickel-cobalt-manganese ternary material, the positive electrode conductive agent is composed of point conductive agent conductive carbon black, branched chain conductive agent carbon nanofiber and sheet layered conductive agent graphene according to a mass ratio of 4:2:1, and the positive electrode binder is polyvinylidene fluoride;
s2, adding the positive active material, the conductive carbon black and the polyvinylidene fluoride into a slurry mixing pot, stirring for 20min at a stirring speed of revolution 30rpm, then adding an NMP solution with the mass of the positive active material of 1/4, and stirring for 30min at a stirring speed of revolution 30 rpm; adding carbon nanofiber and graphene slurry, stirring at the revolution speed of 30rpm for 10min, vacuumizing (the vacuum degree is less than or equal to-0.08 MPa), and stirring at the revolution speed of 30rpm and the rotation speed of 2000rpm for 180 min; after stirring, sieving the slurry by a 150-mesh sieve to prepare anode slurry for later use;
s3, weighing a negative electrode active material, a negative electrode conductive agent, a dispersing agent and a negative electrode binder according to a mass ratio of 95:1.5:1.5:2, wherein the negative electrode active material is graphite, the negative electrode conductive agent is conductive carbon black, the dispersing agent is sodium carboxymethyl cellulose, and the negative electrode binder is styrene-butadiene rubber emulsion;
s4, adding the negative electrode active material, the conductive carbon black and the sodium carboxymethyl cellulose into a slurry mixing pot, stirring for 20min at a stirring speed of revolution 25rpm, then adding deionized water with the mass of 1/3 of the negative electrode active material, stirring for 10min at a stirring speed of revolution 25rpm, and stirring for 120min at a stirring speed of revolution 25rpm and rotation 1500 rpm; then vacuumizing (the vacuum degree is less than or equal to-0.08 MPa), and stirring for 120min at revolution speed of 25rpm and rotation speed of 2000 rpm; adding styrene-butadiene rubber emulsion, vacuumizing (vacuum degree is less than or equal to-0.08 MPa), and stirring at revolution speed of 20rpm for 30 min; after stirring, sieving the slurry with a 150-mesh sieve to prepare cathode slurry for later use;
s5, coating the positive electrode slurry prepared in the step S2 on two surfaces of an aluminum foil of a positive electrode current collector, wherein the single-side surface density is 16mg/cm2Rolling to 105 μm, and die cutting to obtain a positive plate; coating the negative electrode slurry obtained in the step S4 on two surfaces of the copper foil of the negative electrode current collector, wherein the single-side surface density is 9.5mg/cm2Rolling to 128 mu m, and die cutting to obtain a negative plate;
and S6, stacking the positive plate and the negative plate obtained in the step 5 with a diaphragm, wherein the diaphragm is arranged between the positive plate and the negative plate, and thus obtaining the battery cell.
The battery cell prepared by the method comprises a positive plate, a negative plate and a diaphragm arranged between the positive plate and the negative plate; the positive plate comprises a positive current collector aluminum foil and a positive active material layer arranged on the positive current collector aluminum foil, the positive active material layer comprises a positive active material nickel-cobalt-manganese ternary material, a positive conductive agent and positive binder polyvinylidene fluoride with the mass ratio of 96.2:2.8:1, and the positive conductive agent comprises point conductive agent conductive carbon black, branched chain conductive agent carbon nanofiber and lamellar conductive agent graphene with the mass ratio of 4:2: 1; the negative plate comprises a negative current collector copper foil and a negative active material layer arranged on the negative current collector, wherein the negative active material layer comprises negative active material graphite, a negative conductive agent conductive carbon black, a dispersing agent carboxymethylcellulose sodium and a negative binder styrene butadiene rubber in a mass ratio of 95:1.5:1.5: 2.
Comparative example 3
The comparative example is used for preparing a battery cell, and the dispersing agent in the negative electrode slurry of the comparative example is carboxymethyl cellulose sodium which is a conventional dispersing agent. The specific preparation process comprises the following steps:
s1, weighing a positive electrode active material, a positive electrode conductive agent and a positive electrode binder according to a mass ratio of 96.5:2.5:1, wherein the positive electrode active material is a nickel-cobalt-manganese ternary material, the positive electrode conductive agent consists of point conductive agent conductive carbon black, a branched chain conductive agent multiwall carbon nanotube and a lamellar conductive agent graphene according to a mass ratio of 4:2:1, and the positive electrode binder is polyvinylidene fluoride;
s2, adding the positive active material, the conductive carbon black and the polyvinylidene fluoride into a slurry mixing pot, stirring for 20min at a stirring speed of revolution 30rpm, then adding an NMP solution with the mass of the positive active material of 1/5, and stirring for 30min at a stirring speed of revolution 30 rpm; then adding the multi-walled carbon nanotube and the graphene slurry, stirring for 10min at the revolution speed of 30rpm, vacuumizing (the vacuum degree is less than or equal to-0.08 MPa), and stirring for 180min at the revolution speed of 30rpm and the rotation speed of 2000 rpm; after stirring, sieving the slurry by a 150-mesh sieve to prepare anode slurry for later use;
s3, weighing a negative electrode active material, a negative electrode conductive agent, a dispersing agent and a negative electrode binder according to a mass ratio of 95.5:1:1.5:2, wherein the negative electrode active material is graphite, the negative electrode conductive agent is composed of a dotted conductive agent conductive carbon black and a branched conductive agent single-walled carbon nanotube according to a mass ratio of 2:1, the dispersing agent is sodium carboxymethyl cellulose, and the negative electrode binder is styrene butadiene rubber emulsion;
s4, adding the negative electrode active material, the conductive carbon black and the sodium carboxymethyl cellulose into a slurry mixing pot, stirring for 20min at a stirring speed of revolution 25rpm, then adding deionized water with the mass of 1/3 of the negative electrode active material, stirring for 10min at a stirring speed of revolution 25rpm, and stirring for 120min at a stirring speed of revolution 25rpm and rotation 1500 rpm; then adding single-walled carbon nanotube slurry, vacuumizing (the vacuum degree is less than or equal to-0.08 MPa), and then stirring for 120min at revolution speed of 25rpm and rotation speed of 2000 rpm; adding styrene-butadiene rubber emulsion, vacuumizing (vacuum degree is less than or equal to-0.08 MPa), and stirring at revolution speed of 20rpm for 30 min; after stirring, sieving the slurry with a 150-mesh sieve to prepare cathode slurry for later use;
s5, coating the positive electrode slurry prepared in the step S2 on two surfaces of an aluminum foil of a positive electrode current collector, wherein the single-side surface density is 16mg/cm2Rolling to 105 μm, and die cutting to obtain a positive plate; coating the negative electrode slurry obtained in the step S4 on two surfaces of the copper foil of the negative electrode current collector, wherein the single-side surface density is 9.5mg/cm2Rolled to 128 μm, die-cut,preparing a negative plate;
and S6, stacking the positive plate and the negative plate obtained in the step 5 with a diaphragm, wherein the diaphragm is arranged between the positive plate and the negative plate, and thus obtaining the battery cell.
The battery cell prepared by the method comprises a positive plate, a negative plate and a diaphragm arranged between the positive plate and the negative plate; the positive plate comprises a positive current collector aluminum foil and a positive active material layer arranged on the positive current collector aluminum foil, the positive active material layer comprises a positive active material nickel-cobalt-manganese ternary material, a positive conductive agent and positive binder polyvinylidene fluoride in a mass ratio of 96.5:2.5:1, and the positive conductive agent comprises point conductive agent conductive carbon black, a branched chain conductive agent multiwall carbon nanotube and lamellar conductive agent graphene in a mass ratio of 4:2: 1; the negative plate comprises a negative current collector copper foil and a negative active material layer arranged on the negative current collector, the negative active material layer comprises negative active material graphite, a negative conductive agent, a dispersing agent sodium carboxymethyl cellulose and negative binder styrene butadiene rubber in a mass ratio of 95.5:1:1.5:2, and the negative conductive agent comprises point conductive agent conductive carbon black and a branched chain conductive agent single-walled carbon nanotube in a mass ratio of 2: 1.
Comparative example 4
The comparative example is used for preparing a battery cell, and the positive electrode conductive agent in the positive electrode slurry of the comparative example is a branched chain conductive agent. The specific preparation process comprises the following steps:
s1, weighing a positive electrode active material, a positive electrode conductive agent and a positive electrode binder according to a mass ratio of 96:3:1, wherein the positive electrode active material is a nickel-cobalt-manganese ternary material, the positive electrode conductive agent is carbon nanofiber, and the positive electrode binder is polyvinylidene fluoride;
s2, adding the positive active material and polyvinylidene fluoride into a slurry mixing pot, stirring for 20min at a stirring speed of revolution 30rpm, then adding an NMP solution with the mass of the positive active material of 1/5, and stirring for 30min at a stirring speed of revolution 30 rpm; adding carbon nanofiber slurry, stirring at revolution speed of 30rpm for 10min, vacuumizing (vacuum degree is less than or equal to-0.08 MPa), and stirring at revolution speed of 30rpm and rotation speed of 2000rpm for 180 min; after stirring, sieving the slurry by a 150-mesh sieve to prepare anode slurry for later use;
s3, weighing a negative electrode active material, a negative electrode conductive agent, a dispersing agent and a negative electrode binder according to a mass ratio of 95:1.5:1.5:2, wherein the negative electrode active material is graphite, the negative electrode conductive agent is composed of a dot conductive agent conductive carbon black and a branched chain conductive agent carbon nanofiber according to a mass ratio of 2:1, the dispersing agent is lithium carboxymethyl cellulose, and the negative electrode binder is styrene-butadiene rubber emulsion;
s4, adding the negative electrode active material, the conductive carbon black and the lithium carboxymethyl cellulose into a slurry mixing pot, stirring for 20min at a stirring speed of revolution 25rpm, then adding deionized water with the mass of 1/3 of the negative electrode active material, stirring for 10min at a stirring speed of revolution 25rpm, and stirring for 120min at a stirring speed of revolution 25rpm and rotation 1500 rpm; then adding the carbon nanofiber slurry, vacuumizing (the vacuum degree is less than or equal to-0.08 MPa), and then stirring for 120min at revolution speed of 25rpm and rotation speed of 2000 rpm; adding styrene-butadiene rubber emulsion, vacuumizing (vacuum degree is less than or equal to-0.08 MPa), and stirring at revolution speed of 20rpm for 30 min; after stirring, sieving the slurry with a 150-mesh sieve to prepare cathode slurry for later use;
s5, coating the positive electrode slurry prepared in the step S2 on two surfaces of an aluminum foil of a positive electrode current collector, wherein the single-side surface density is 16mg/cm2Rolling to 105 μm, and die cutting to obtain a positive plate; coating the negative electrode slurry obtained in the step S4 on two surfaces of the copper foil of the negative electrode current collector, wherein the single-side surface density is 9.5mg/cm2Rolling to 128 mu m, and die cutting to obtain a negative plate;
and S6, stacking the positive plate and the negative plate obtained in the step 5 with a diaphragm, wherein the diaphragm is arranged between the positive plate and the negative plate, and thus obtaining the battery cell.
The battery cell prepared by the method comprises a positive plate, a negative plate and a diaphragm arranged between the positive plate and the negative plate; the positive plate comprises a positive current collector aluminum foil and a positive active material layer arranged on the positive current collector aluminum foil, wherein the positive active material layer comprises a positive active material nickel-cobalt-manganese ternary material, a positive conductive agent carbon nanofiber and a positive binder polyvinylidene fluoride in a mass ratio of 96:3: 1; the negative plate comprises a negative current collector copper foil and a negative active material layer arranged on the negative current collector, the negative active material layer comprises negative active material graphite, a negative conductive agent, a dispersing agent carboxymethyl cellulose lithium and negative binder styrene butadiene rubber in a mass ratio of 95:1.5:1.5:2, and the negative conductive agent comprises point conductive agent conductive carbon black and branched chain conductive agent carbon nanofiber in a mass ratio of 2: 1.
Test examples
The battery cell prepared in each of the above embodiments and comparative examples can be further used for preparing a fast-charging lithium ion battery, for example, the fast-charging lithium ion battery can be prepared by sequentially performing tab welding, aluminum plastic film packaging, baking, liquid injection, formation, secondary sealing and capacity grading on the battery cell. The battery cells prepared in the above examples 1 to 4 and comparative examples 1 to 4 are respectively adopted to correspondingly prepare the fast charging lithium ion batteries C1-C8 # according to the same method similar to the above.
Test examples
The test example tests the performance, including cycle performance, of each of the fast-charging lithium ion batteries C1# to C8# prepared in the above application examples. The test method of the cycle performance comprises the following steps: under the condition of room temperature at 25 ℃, the cycle charge and discharge current is 1C/1C, the voltage range is 2.8-4.3V, the cycle frequency is 2000 times, the cycle capacity retention rate of the fast-charging lithium ion battery C1# -C8 # is tested, and the obtained results are shown in figures 1-8.
As can be seen from fig. 1 to 4, in the battery cells of examples 1 to 4, the conductive agent in the positive and negative electrode active material layers is formed by mixing components including a dot conductive agent and a branched conductive agent, and the dispersant in the negative electrode active material layer on the negative electrode sheet adopts lithium carboxymethyl cellulose to replace the conventional sodium carboxymethyl cellulose as the dispersant, so that the fast-charging lithium ion batteries C1# to C4# prepared from the battery cells have excellent long-term cycle performance; as is clear from fig. 4, in the battery cell of example 1, the number of the sheet-like conductive agents in addition to the point-like conductive agents and the branched-chain conductive agents in the conductive agents of the positive electrode active material layer was increased, and the cycle life of the battery was further prolonged, as compared to the battery cell of example 4. As can be seen from fig. 5, the battery cell of comparative example 1 only improves the negative active material layer, and the conductive agent in the positive active material layer adopts the conventional conductive agent, so that the cycle performance of the fast-charging lithium ion battery C5# prepared by the method is significantly reduced compared with the fast-charging lithium ion battery C1# prepared by the battery cell of example 1; as can be seen from fig. 6, the battery cell of comparative example 2 is obtained by improving only the positive active material layer, and the negative active material layer adopts the conventional conductive agent and the conventional dispersant, so that the cycle performance of the fast-charging lithium ion battery C6# prepared by the battery cell of comparative example 2 is significantly reduced compared with the cycle performance of the fast-charging lithium ion battery C2# prepared by the battery cell of example 2. As can be seen from fig. 7, in the battery cell of comparative example 3, the positive electrode active material layer is improved, and the conductive agent in the negative electrode active material layer is improved, but the dispersant in the negative electrode active material layer adopts the conventional dispersant, and the cycle performance of the fast charging lithium ion battery C7# prepared by the battery cell of example 1 is significantly reduced compared with that of the fast charging lithium ion battery C1# prepared by the battery cell of example 1. In addition, as can be seen from fig. 8, the negative active material layer of the battery cell of comparative example 4 is modified, and the conductive agent in the positive active material layer is only branched, so that the cycle performance of the fast-charging lithium ion battery C8# prepared by the method is significantly reduced compared with the cycle performance of the fast-charging lithium ion battery C2# prepared by the battery cell of example 2. From the above, the conductive agent in the positive and negative electrode active material layers is matched by adopting the components including the point conductive agent and the branched chain conductive agent, and is cooperated with the use of the carboxymethyl cellulose lithium as the dispersing agent in the negative electrode active material layer on the negative electrode sheet, so that the cycle performance of the fast-charging lithium ion battery can be obviously improved.
In addition, tests show that the energy density of the lithium ion battery C1-C4 # is more than 250Wh/Kg, the normal-temperature cycle life is more than 2000 weeks, the lithium ion battery can be rapidly charged at 4C multiplying power, and lithium is not separated out; and the conventional lithium ion battery purchased from the market is charged at 4C rate to separate out lithium seriously. In the above embodiments, the conductive agent in the positive and negative active material layers is matched with the components including the dot conductive agent and the branched conductive agent, and cooperates with the carboxymethyl cellulose lithium as the dispersant in the negative active material layer on the negative electrode sheet, so that the ionic conductivity can be improved, a fast channel is provided for ion and electron transmission, and the charge rate performance and the cycle performance of the battery can be improved while the energy density is ensured.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.
Claims (10)
1. A battery cell, comprising:
the positive plate comprises a positive current collector and a positive active material layer arranged on the positive current collector, and the material of the positive active material layer comprises a positive active material, a positive conductive agent and a positive binder; the positive electrode conductive agent comprises a first point-shaped conductive agent and a first branched chain-shaped conductive agent;
the negative plate comprises a negative current collector and a negative active material layer arranged on the negative current collector, wherein the negative active material layer comprises a negative active material, a negative conductive agent, a dispersing agent and a negative binder; the negative electrode conductive agent comprises a second point conductive agent and a second branched chain conductive agent, and the dispersing agent is selected from carboxymethyl cellulose lithium;
and the diaphragm is arranged between the positive plate and the negative plate.
2. The battery cell of claim 1, wherein the first dot-shaped conductive agent and the second dot-shaped conductive agent are selected from conductive carbon black, the first branched-chain-shaped conductive agent is selected from at least one of ketjen black, multi-walled carbon nanotubes, and carbon nanofibers, and the second branched-chain-shaped conductive agent is selected from at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon nanofibers.
3. The battery cell of claim 1, wherein the composition of the positive electrode conductive agent further comprises a sheet-like conductive agent; preferably, the sheet-like conductive agent is selected from graphene.
4. The battery cell of claim 3, wherein the positive electrode conductive agent comprises the first point-like conductive agent, the first branch-chain-like conductive agent, and the sheet-like conductive agent in a mass ratio of 4:2: 1; the negative electrode conductive agent comprises the following components in percentage by mass: 1 and a second branched conductive agent.
5. The battery cell of claim 1, wherein the material of the positive electrode active material layer comprises 93 wt% to 97 wt% positive electrode active material, 0.5 wt% to 3 wt% positive electrode conductive agent, and 1 wt% to 4 wt% positive electrode binder; the material of the negative active material layer comprises 93-97 wt% of negative active material, 0.5-2 wt% of negative conductive agent, 0.5-2 wt% of dispersant and 0.5-3 wt% of negative binder.
6. The battery cell of claim 5, wherein the positive electrode active material is selected from a nickel-cobalt-manganese ternary material, and the positive electrode binder is selected from polyvinylidene fluoride; the negative electrode active material is selected from graphite, and the negative electrode binder is selected from at least one of styrene-butadiene rubber and polyacrylic acid glue.
7. The battery cell of any of claims 1 to 6, wherein the positive current collector is selected from aluminum foil and the negative current collector is selected from copper foil.
8. The method of making a battery cell of any of claims 1 to 7, comprising the steps of:
mixing the material of the positive electrode active material layer with a first solvent to prepare positive electrode slurry; coating the positive electrode slurry on the surface of a positive electrode current collector, drying, rolling and die cutting to obtain a positive plate;
mixing the material of the negative electrode active material layer with a second solvent to prepare negative electrode slurry; coating the negative electrode slurry on the surface of a negative electrode current collector, drying, rolling and die cutting to prepare a negative electrode sheet;
and arranging a diaphragm between the positive plate and the negative plate to obtain the battery core.
9. The method of making a battery cell of claim 8, wherein the first solvent is N-methylpyrrolidone and the second solvent is deionized water.
10. A fast-charging lithium ion battery comprising the battery cell of any of claims 1 to 7.
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Application publication date: 20210716 |