CN114883565A - Large-column bi-water system lithium iron phosphate battery and preparation method thereof - Google Patents
Large-column bi-water system lithium iron phosphate battery and preparation method thereof Download PDFInfo
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- CN114883565A CN114883565A CN202210655311.6A CN202210655311A CN114883565A CN 114883565 A CN114883565 A CN 114883565A CN 202210655311 A CN202210655311 A CN 202210655311A CN 114883565 A CN114883565 A CN 114883565A
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 102
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 title claims abstract description 73
- 238000002360 preparation method Methods 0.000 title claims abstract description 8
- 238000000576 coating method Methods 0.000 claims abstract description 82
- 239000011248 coating agent Substances 0.000 claims abstract description 80
- 239000011230 binding agent Substances 0.000 claims abstract description 63
- 239000006258 conductive agent Substances 0.000 claims abstract description 62
- 239000007787 solid Substances 0.000 claims abstract description 62
- 238000004804 winding Methods 0.000 claims abstract description 35
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 24
- 229910021383 artificial graphite Inorganic materials 0.000 claims abstract description 19
- 239000002041 carbon nanotube Substances 0.000 claims abstract description 17
- 229910021393 carbon nanotube Inorganic materials 0.000 claims abstract description 17
- 239000002002 slurry Substances 0.000 claims abstract description 17
- 239000002131 composite material Substances 0.000 claims abstract description 13
- 239000007864 aqueous solution Substances 0.000 claims abstract description 8
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 4
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 4
- 239000011889 copper foil Substances 0.000 claims abstract description 4
- 239000011888 foil Substances 0.000 claims abstract description 4
- 238000002156 mixing Methods 0.000 claims description 46
- 238000000034 method Methods 0.000 claims description 31
- 239000011267 electrode slurry Substances 0.000 claims description 14
- 238000005096 rolling process Methods 0.000 claims description 9
- 238000005056 compaction Methods 0.000 claims description 8
- 239000011149 active material Substances 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 6
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 4
- 238000001914 filtration Methods 0.000 claims description 4
- 239000006256 anode slurry Substances 0.000 claims description 3
- 238000001035 drying Methods 0.000 claims description 3
- 229920001577 copolymer Polymers 0.000 claims 1
- 230000007613 environmental effect Effects 0.000 abstract description 3
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 16
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 16
- 230000000052 comparative effect Effects 0.000 description 15
- 239000002904 solvent Substances 0.000 description 10
- 239000000203 mixture Substances 0.000 description 9
- 238000001514 detection method Methods 0.000 description 8
- 239000004480 active ingredient Substances 0.000 description 6
- 230000032683 aging Effects 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 6
- 238000000265 homogenisation Methods 0.000 description 6
- 238000002347 injection Methods 0.000 description 6
- 239000007924 injection Substances 0.000 description 6
- 239000007788 liquid Substances 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 239000000178 monomer Substances 0.000 description 6
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000013543 active substance Substances 0.000 description 4
- 229910021389 graphene Inorganic materials 0.000 description 4
- 239000002033 PVDF binder Substances 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 229910052744 lithium Inorganic materials 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000005979 thermal decomposition reaction Methods 0.000 description 2
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 1
- 239000006257 cathode slurry Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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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
- H01M4/621—Binders
- H01M4/622—Binders being polymers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
- H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/028—Positive electrodes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Abstract
The invention discloses a large-cylinder bi-water system lithium iron phosphate battery and a preparation method thereof, wherein the large-cylinder bi-water system lithium iron phosphate battery is formed by overlapping and winding a positive pole piece, a diaphragm and a negative pole piece; the diaphragm comprises a first diaphragm and a second diaphragm; the anode plate comprises an aluminum foil and a water-system anode coating, and the water-system anode coating comprises lithium iron phosphate, an anode conductive agent and an anode water-system binder; the negative pole piece comprises copper foil and a water-system negative pole coating, wherein the water-system negative pole coating comprises artificial graphite, a negative pole conductive agent, a negative pole water-system binder and CMC; the anode conductive agent is a carbon nano tube composite conductive slurry aqueous solution with the solid content of 2-15%; the negative electrode conductive agent is a carbon nano tube composite conductive slurry aqueous solution with the solid content of 5-20%; the anode water system binder and the cathode water system binder are 3-30% of water-based binders. The invention has the advantages of large battery capacity, safety, environmental protection and excellent safety performance.
Description
Technical Field
The invention relates to the technical field of lithium iron phosphate batteries, in particular to a large cylindrical bi-water system lithium iron phosphate battery and a preparation method thereof.
Background
The cylindrical battery is in a battery form with mature manufacturing process, good consistency, safety and reliability.
In the long run, with the rapid development of new energy industries, lithium batteries have a wide application prospect in people's daily life and various industries, but this inevitably puts higher demands on the aspects of large capacity, simple assembly process, easy quality control, reliability, safety and environmental protection of the batteries.
The lithium iron phosphate battery has good thermal stability and cycle performance, and becomes the main force of a new generation of lithium battery.
The existing lithium iron phosphate battery is mainly manufactured by adopting oil-based slurry, wherein the oil-based slurry generally comprises a solvent N-methylpyrrolidone (NMP) and a binder PVDF. However, the oil-based lithium iron phosphate battery has some problems, firstly, the price of the oil-based slurry solvent NMP and the binder PVDF is high; secondly, the required temperature is high during baking, and an NMP recovery device is required to be added, so that the equipment cost and the processing energy consumption are high, and the environment is polluted when the NMP is not sufficiently recovered; the PVDF as the binder in the secondary oil slurry can generate a heating reaction in the working environment of 200-300 ℃, and the safety performance is relatively poor.
At present, the capacity of the cylindrical battery is smaller, the capacity requirement can be only compensated by greatly increasing the number, and the requirement of a larger number of batteries on a battery management system is higher.
Disclosure of Invention
In view of the defects existing at present, the invention provides a large cylindrical bi-aqueous lithium iron phosphate battery and a preparation method thereof, the battery has large capacity, the pole piece does not have the phenomena of powder falling, material falling and the like, the pole piece has good softness and cohesiveness after being rolled, safety and environmental protection are realized, excellent performances are realized in the rear end process of the battery and the manufacturing process of the battery, the aqueous binder has good high-temperature performance, no thermal decomposition reaction is generated at the temperature of more than 300 ℃, the safety performance is excellent, the hollow pipeline structure of the carbon nano tube improves the content of positive and negative active substances and the electric conductivity of the pole piece, the capacity of a single battery is remarkably improved, the number of single batteries and accessories required by battery pack grouping is greatly reduced, and the grouping efficiency is improved.
In order to achieve the purpose, the invention provides a large cylindrical bi-water system lithium iron phosphate battery, which is formed by overlapping and winding a positive pole piece, a diaphragm and a negative pole piece; the diaphragm comprises a first diaphragm and a second diaphragm; the anode plate comprises an aluminum foil and a water-system anode coating, and the water-system anode coating comprises lithium iron phosphate, an anode conductive agent and an anode water-system binder; the negative pole piece comprises copper foil and a water-system negative pole coating, wherein the water-system negative pole coating comprises artificial graphite, a negative pole conductive agent, a negative pole water-system binder and CMC; the anode conductive agent is a carbon nano tube composite conductive slurry aqueous solution with the solid content of 2-15%; the negative electrode conductive agent is a carbon nano tube composite conductive slurry aqueous solution with the solid content of 5-20%; the anode water system binder and the cathode water system binder are 3-30% of water-based binders.
According to one aspect of the present invention, the water-based positive electrode coating is composed of the following mass ratios: lithium iron phosphate: positive electrode conductive agent (active material): the positive electrode aqueous binder (effective substance) is 90-98:1-5: 1-5.
According to an aspect of the present invention, the water-based negative electrode coating is composed of the following mass ratios: artificial graphite: negative electrode conductive agent (effective substance): negative electrode aqueous binder (active material): CMC is 90-98:0.5-3:1-5: 0.5-3.
In accordance with one aspect of the present invention, the water-based positive electrode coating has an areal density of 300-500g/m 2 The rolling compaction density is 2.1-2.3g/cm 3 。
In accordance with one aspect of the present invention, the water-based negative electrode coating has an areal density of 160-260g/m 2 The rolling compaction density is 1.45-1.6g/cm 3 。
According to one aspect of the invention, the single large cylindrical double-water system lithium iron phosphate battery comprises model 60200-50Ah and model 60320-100 Ah; the model 60200-50Ah and the model 60320-100Ah both have the diameter of 60mm and the height of 300mm, and the model 60200-50Ah and the model 60320-100Ah have different heights.
In accordance with one aspect of the invention, the aqueous binder is an acrylic multipolymer.
Based on the same inventive concept, the invention also provides a preparation method of the large cylindrical bi-water system lithium iron phosphate battery, which comprises the following steps:
homogenizing: comprises anode homogenate and cathode homogenate; the anode homogenate is that the anode conductive agent and the anode aqueous binder are mixed uniformly, then the lithium iron phosphate is added for size mixing, then the pure water is added for uniform mixing, and the anode slurry is obtained by filtering; the negative pole homogenate is that the negative pole conductive agent and the negative pole aqueous binder are mixed evenly, then the artificial graphite and the pure water are added for size mixing, then the CMC and the pure water are added in sequence for even mixing and filtration, and the negative pole slurry is prepared;
coating and tabletting: coating the positive electrode slurry and the negative electrode slurry on the surface of the positive and negative electrode current collector, drying, rolling and cutting to obtain a positive electrode piece and a negative electrode piece;
winding: the diaphragm is manufactured by overlapping and winding the positive pole piece, the first diaphragm, the negative pole piece and the second diaphragm.
According to one aspect of the invention, the anode homogenate is that the anode conductive agent and the anode aqueous binder are uniformly mixed to solid content of 5-15%, then the lithium iron phosphate is added to carry out size mixing to solid content of 65-85%, and then the pure water is added to uniformly mix to solid content of 55-65%; the negative pole homogenate is that the negative pole conductive agent and the negative pole aqueous binder are mixed uniformly until the solid content is 5-15%, then the artificial graphite and the pure water are added for size mixing until the solid content is 60-75%, and then the CMC and the pure water are sequentially added for uniform mixing until the solid content is 45-55%.
According to one aspect of the present invention, the coated sheet is coated by double coating at a speed of 40 m/min, and is baked in a 40 m long oven at a temperature of 80-120 ℃ after coating of each layer, the diameter of the wound winding needle is 6-12mm, and the wound length of the positive electrode sheet and the negative electrode sheet is 6-8 m.
The invention has the beneficial effects that:
(1) in the process of batching and coating, the water-based positive and negative electrode slurry and water are used as solvents, so that the coating is safe and environment-friendly; through the matching of materials and the optimization of the process, the phenomena of powder removal, material falling and the like of the pole piece can not occur, and the pole piece has good softness and cohesiveness after being rolled; and has excellent performance in the battery back-end process and the battery manufacturing process. Meanwhile, the water system binder has good high-temperature performance, does not generate thermal decomposition reaction at the temperature of more than 300 ℃, and has excellent safety performance.
(2) The invention uses the water-based carbon nano tube conductive composite slurry as a conductive agent, not only cooperates with a water-based process environment, but also improves the content of positive and negative active substances and the conductivity of a pole piece due to the hollow pipeline structure of the carbon nano tube.
(3) The 60200 lithium iron phosphate battery manufactured by the conventional process on the basis of the battery prepared by the invention has the monomer capacity of more than 50Ah, the system energy density of more than 148Wh/Kg, the monomer capacity of 60320 lithium iron phosphate battery of more than 100Ah and the system energy density of more than 170Wh/Kg, thereby not only having considerable improvement on the capacity of a single battery, but also greatly reducing the number of the monomer batteries and accessories required by battery pack grouping and improving the grouping efficiency.
Drawings
FIG. 1 is a graph of cell cycling tests from 60200 to 50Ah for cells made according to example 3 of the present invention.
Detailed Description
In order that the invention may be more readily understood, reference will now be made to the following examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention, and it should be understood that the described examples are only a portion of the examples of the present invention, rather than the entire scope of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. Unless otherwise defined, the terms used hereinafter are consistent with the meaning understood by those skilled in the art; unless otherwise specified, CMC is a carboxymethyl cellulose binder.
The invention provides a large cylindrical lithium iron phosphate battery, wherein a positive pole piece comprises an aluminum foil and a water system positive pole coatingThe water system anode coating comprises lithium iron phosphate, an anode conductive agent and an anode water system binder; the negative pole piece comprises copper foil and a water-system negative pole coating, and the water-system negative pole coating comprises artificial graphite, a negative pole conductive agent, a negative pole water-system binder and CMC; the surface density of the water system anode coating is 300-500g/m 2 The rolling compaction density is 2.1-2.3g/cm 3 。
Preferably, the surface density of the water-based positive electrode coating of the 50Ah battery (model 60200-50Ah) is 380g/m 2 The density of the rolled compact is 2.12g/cm 3 (ii) a The surface density of the water-based positive electrode coating of the 100Ah battery ((model 60300-100 Ah)) is 440g/m 2 The density of the rolled compact is 2.16g/cm 3 。
The surface density of the water-based negative electrode coating is 160-260g/m 2 The rolling compaction density is 1.45-1.6g/cm 3 。
Preferably, the surface density of the water-based negative electrode coating of the 50Ah battery (model 60200-50Ah) is 175g/m 2 The rolled compacted density is 1.5g/cm 3 (ii) a The surface density of a 100Ah battery ((model 60300-100Ah) water-based negative electrode coating is 205g/m 2 The density of the rolled compact is 1.53g/cm 3 。
The water system positive electrode coating is prepared from the following raw materials in percentage by mass: lithium iron phosphate: positive electrode conductive agent (active material): the positive pole water system binder (effective substance) is 90-98:1-5: 1-5; the water system negative electrode coating is prepared from the following raw materials in percentage by mass: artificial graphite: negative electrode conductive agent (effective substance): negative electrode aqueous binder (active material): CMC is 90-98:0.5-3:1-5: 0.5-3;
preferably, the positive electrode conductive agent and the negative electrode conductive agent are carbon nanotube composite conductive slurry;
more preferably, the positive electrode conductive agent is a carbon nanotube composite conductive slurry aqueous solution with a solid content of 2% -15%, and the negative electrode conductive agent is a carbon nanotube composite conductive slurry aqueous solution with a solid content of 5% -20%.
Preferably, the positive and negative electrode aqueous binders are 3% to 30% of an aqueous binder, and more preferably, an acrylic acid multipolymer (PAA).
The battery manufacturing method comprises the following steps: homogenizing S1, preparing S2 coating tablets, and winding S3;
the step S1 comprises anode homogenate and cathode homogenate;
the step S1 of homogenizing the positive electrode is that the positive electrode conductive agent is firstly mixed with the positive electrode aqueous binder uniformly, then the lithium iron phosphate is added for size mixing, then the pure water is added for uniform mixing, and then the mixture is filtered by a screen with 150-mesh and 200-mesh to prepare positive electrode slurry;
preferably, the positive electrode conductive agent and the positive electrode aqueous binder are uniformly mixed until the solid content is 5-15%, lithium iron phosphate is added for size mixing until the solid content is 65-85%, and then pure water is added for uniform mixing until the solid content is 55-65%;
the step S1 of homogenizing the negative electrode is that the negative electrode conductive agent and the negative electrode aqueous binder are mixed uniformly, then the artificial graphite and part of the pure water are added for size mixing, then the CMC and the pure water are sequentially added for uniform mixing, and then the mixture is filtered by a 120-mesh and 150-mesh screen to obtain the negative electrode slurry;
preferably, the negative electrode conductive agent and the negative electrode water system binder are uniformly mixed until the solid content is 5-15%, the artificial graphite and part of pure water are added to be mixed until the solid content is 60-75%, and then the CMC and the pure water are sequentially added to be uniformly mixed until the solid content is 45-55%;
preferably, the material preparation and homogenate mode adopts the carbon nano tube as a conductive agent to improve the content and the conductivity of active substances of the positive and negative pole pieces, adopts water as a solvent to cause no pollution to the environment, does not generate phenomena of powder shedding, material falling and the like in the coating process of manufacturing large-size pole pieces, and has excellent and stable performance of the positive and negative pole pieces, thereby manufacturing the large cylindrical battery.
Coating and flaking in the step S2, namely coating the positive and negative electrode slurry on the surfaces of the positive and negative electrode current collectors, drying, rolling and cutting to obtain positive and negative electrode flakes;
in the step S2, double-layer coating is adopted to coat at the speed of 40 m/min, and after each layer of coating is finished, baking is carried out in a 40-meter-length oven at the temperature of 80-120 ℃;
in the step S3, winding, overlapping and winding the positive electrode sheet, the first diaphragm, the negative electrode sheet and the second diaphragm to form a battery;
in the step S3, the diameter phi of the winding needle is 6-12mm, and the winding length of the pole piece is 6-8 m;
preferably, the diameter phi of the winding needle is 8mm, and the winding length of the pole piece is 6.8 m;
in the step S1, the viscosity of the anode slurry is 7000-15000Pa.s, and the viscosity of the cathode slurry is 2000-6000 Pa.s;
in the step S2, after slitting, the width of the positive plate is more than or equal to 165mm, the width of the positive coating is more than or equal to 152mm, the width of the negative plate is more than or equal to 167mm, and the width of the negative coating is more than or equal to 153 mm; in the step S2, the moisture content of the anode and cathode coatings is less than or equal to 2000 ppm.
After the large cylindrical lithium iron phosphate batteries are manufactured into batteries according to a conventional process, a single lithium iron phosphate battery can reach 60mm, and is divided into 60200 batteries, 60320 batteries and the like according to the types of the batteries, wherein the capacity of the single battery 60200 exceeds 50Ah, the energy density of the system exceeds 148Wh/Kg, the capacity of the single battery 60320 exceeds 100Ah, and the energy density of the system exceeds 170 Wh/Kg.
The most preferred, specific parameters and procedures described above were prepared for the following examples 1-4, with specific parameters not provided above, see examples 1-4, and others not specified may be derived from other parameters and are within routine practice in the art.
Example 1
A large cylindrical bi-water system lithium iron phosphate battery comprises the following active ingredients except a solvent in positive electrode slurry by weight percent:
lithium iron phosphate: 92.5 percent;
positive electrode conductive agent: 2.5 percent;
positive electrode aqueous binder: 5 percent;
the lithium iron phosphate battery is prepared by the following steps:
s1 homogenization: uniformly mixing the positive electrode conductive agent and the positive electrode aqueous binder until the solid content is 6%, adding lithium iron phosphate to perform size mixing until the solid content is 72%, and then adding pure water to uniformly mix until the solid content is 56%; the negative electrode conductive agent and the negative electrode water system binder are uniformly mixed until the solid content is 12%, the artificial graphite and the pure water are added for size mixing until the solid content is 72%, and then the CMC and the water are added for uniform mixing until the solid content is 54%.
S2 coating and tableting: the coating is carried out at the speed of 40 meters per minute by adopting double-layer coating, and after the coating of each layer is finished, the coating is baked in an oven with the length of 40 meters and the temperature of 80-120 ℃.
S3 winding uses a winding needle with the diameter of 8mm and the winding length of the pole piece of 6.8m, and the processes of liquid injection, formation, aging, detection and the like are conventional process.
Example 2
A large cylindrical bi-water system lithium iron phosphate battery comprises the following active ingredients except a solvent in positive electrode slurry by weight percent:
lithium iron phosphate: 93.5 percent;
positive electrode conductive agent: 3 percent;
positive electrode aqueous binder: 3.5 percent;
the lithium iron phosphate battery is prepared by the following steps:
s1 homogenization: uniformly mixing the positive electrode conductive agent and the positive electrode aqueous binder until the solid content is 8%, adding lithium iron phosphate to perform size mixing until the solid content is 74%, and then adding pure water to uniformly mix until the solid content is 64%; the negative electrode conductive agent and the negative electrode water system binder are uniformly mixed until the solid content is 8%, the artificial graphite and the pure water are added for size mixing until the solid content is 70%, and then the CMC and the water are added for uniform mixing until the solid content is 52%.
S2 coating and tableting: the coating is carried out by double-layer coating at a speed of 40 m/min, and after the coating of each layer is finished, the coating is baked in an oven with the length of 40 m at a temperature of 80-120 ℃.
S3 winding uses a winding needle with the diameter of 8mm and the winding length of the pole piece of 6.8m, and the processes of liquid injection, formation, aging, detection and the like are conventional process.
Example 3
A large cylindrical bi-water system lithium iron phosphate battery comprises the following active ingredients except a solvent in positive electrode slurry by weight percent:
lithium iron phosphate: 94.5 percent;
positive electrode conductive agent: 2.5 percent;
aqueous binder for positive electrode: 3 percent;
the lithium iron phosphate battery is prepared by the following steps:
s1 homogenization: uniformly mixing the positive electrode conductive agent and the positive electrode aqueous binder until the solid content is 10%, adding lithium iron phosphate to perform size mixing until the solid content is 76%, and then adding pure water to uniformly mix until the solid content is 60%; the negative electrode conductive agent and the negative electrode water system binder are uniformly mixed until the solid content is 10%, the artificial graphite and the pure water are added for size mixing until the solid content is 68%, and then the CMC and the water are added for uniform mixing until the solid content is 50%.
S2 coating and tableting: the coating is carried out by double-layer coating at a speed of 40 m/min, and after the coating of each layer is finished, the coating is baked in an oven with the length of 40 m at a temperature of 80-120 ℃.
S3 winding is carried out by using a winding needle with the diameter of 8mm, the winding length of a pole piece is 6.8m, and the processes of liquid injection, formation, aging, detection and the like are the conventional process.
Example 4
A large cylindrical bi-water system lithium iron phosphate battery comprises the following active ingredients except a solvent in positive electrode slurry by weight percent:
lithium iron phosphate: 95.5 percent;
positive electrode conductive agent: 2 percent;
positive electrode aqueous binder: 2.5 percent;
the lithium iron phosphate battery is prepared by the following steps:
s1 homogenization: uniformly mixing the positive electrode conductive agent and the positive electrode aqueous binder until the solid content is 8%, adding lithium iron phosphate to perform size mixing until the solid content is 80%, and then adding pure water to uniformly mix until the solid content is 65%; the negative electrode conductive agent and the negative electrode aqueous binder are uniformly mixed until the solid content is 10%, the artificial graphite and the pure water are added for size mixing until the solid content is 66%, and then the CMC and the water are added for uniform mixing until the solid content is 48%.
S2 coating and tableting: the coating is carried out by double-layer coating at a speed of 40 m/min, and after the coating of each layer is finished, the coating is baked in an oven with the length of 40 m at a temperature of 80-120 ℃.
S3 winding is carried out by using a winding needle with the diameter of 8mm, the winding length of a pole piece is 6.8m, and the processes of liquid injection, formation, aging, detection and the like are the conventional process.
Comparative example 1
Comparative example 1 is compared with example 3, and the part of comparative example 1 not described in detail is the same as example 3.
A large cylindrical bi-water system lithium iron phosphate battery comprises the following active ingredients except a solvent in positive electrode slurry by weight percent:
lithium iron phosphate: 94.5 percent;
the positive electrode conductive agent used was a graphene conductive agent: 2.5 percent;
positive electrode aqueous binder: 3 percent;
the lithium iron phosphate battery is prepared by the following steps:
s1 homogenization: uniformly mixing the graphene conductive agent and the anode aqueous binder until the solid content is 10%, adding lithium iron phosphate to perform size mixing until the solid content is 76%, and then adding pure water to uniformly mix until the solid content is 60%; the negative electrode conductive agent and the negative electrode water system binder are uniformly mixed until the solid content is 10%, the artificial graphite and the pure water are added for size mixing until the solid content is 68%, and then the CMC and the water are added for uniform mixing until the solid content is 50%.
S2 coating and tableting: the coating is carried out by double-layer coating at a speed of 40 m/min, and after the coating of each layer is finished, the coating is baked in an oven with the length of 40 m at a temperature of 80-120 ℃.
S3 winding uses a winding needle with the diameter of 8mm and the winding length of the pole piece of 6.8m, and the processes of liquid injection, formation, aging, detection and the like are conventional process.
Comparative example 2
Comparative example 2 was compared with example 3, and the portions of comparative example 2 not described in detail were the same as example 3.
A large cylindrical bi-water system lithium iron phosphate battery comprises the following active ingredients except a solvent in positive electrode slurry by weight percent:
carbon-coated lithium iron phosphate: 94.5 percent;
positive electrode conductive agent: 2.5 percent;
positive electrode aqueous binder: 3 percent;
the lithium iron phosphate battery is prepared by the following steps:
s1 homogenization: uniformly mixing the positive electrode conductive agent and the positive electrode aqueous binder until the solid content is 10%, adding lithium iron phosphate to perform size mixing until the solid content is 76%, and then adding pure water to uniformly mix until the solid content is 60%; the negative electrode conductive agent and the negative electrode water system binder are uniformly mixed until the solid content is 10%, the artificial graphite and the pure water are added for size mixing until the solid content is 68%, and then the CMC and the water are added for uniform mixing until the solid content is 50%.
S2 coating and tableting: the coating is carried out by double-layer coating at a speed of 40 m/min, and after the coating of each layer is finished, the coating is baked in an oven with the length of 40 m at a temperature of 80-120 ℃.
S3 winding uses a winding needle with the diameter of 8mm and the winding length of the pole piece of 6.8m, and the processes of liquid injection, formation, aging, detection and the like are conventional process.
And (3) performance detection:
the batteries prepared by the methods of the embodiments 1 to 4 can be subjected to performance detection to obtain relatively stable battery performance, wherein the embodiment 3 is optimal, the basic parameters and cycle test data of the 50Ah battery (model 60200-50Ah) prepared by the battery of the embodiment 3 are shown in fig. 1 and table 1, and the basic parameters of the 100Ah battery (model 60320-100Ah) prepared by the embodiment 3 are shown in table 1. The batteries of comparative examples 1-2 were prepared as 50Ah batteries (model numbers 60200-50Ah) and their basic parameters are shown in Table 1.
Table 1 basic parameters of the batteries prepared in example 3, comparative example 1 and comparative example 2
As can be seen from Table 1, the 60200 lithium iron phosphate battery prepared by the conventional process on the basis of the battery prepared by the invention has the monomer capacity of more than 50Ah, the system energy density of more than 148Wh/Kg, the monomer capacity of 60320 lithium iron phosphate battery of more than 100Ah and the system energy density of more than 170Wh/Kg, not only has considerable improvement on the capacity of a single battery, but also greatly reduces the number of the monomer batteries and accessories required by battery pack grouping and improves the grouping efficiency.
As can be seen from example 3 and comparative example 1, compared with the battery prepared from the positive electrode conductive agent (graphene) of comparative example 1, the positive electrode conductive agent (aqueous carbon nanotube composite conductive paste) prepared by the method of the present invention has low internal resistance, high positive electrode compaction density and high mass energy density, and therefore, the method of the present invention using the aqueous carbon nanotube composite conductive paste as the positive electrode conductive agent has outstanding substantial characteristics compared with the method using the graphene of comparative example 1 as the positive electrode conductive agent. The invention uses the water-based carbon nano tube conductive composite slurry as a conductive agent, not only cooperates with a water-based process environment, but also improves the content of positive and negative active substances and the conductivity of a pole piece due to the hollow pipeline structure of the carbon nano tube.
As can be seen from example 3 and comparative example 2, compared with the battery prepared from the carbon-coated lithium iron phosphate of comparative example 2, the lithium iron phosphate prepared by the method has low internal resistance, high positive electrode compaction density and high mass energy density, and therefore, the lithium iron phosphate adopted by the method has outstanding substantive characteristics compared with the carbon-coated lithium iron phosphate adopted by the comparative example 2.
The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention disclosed herein are intended to be covered by the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (10)
1. A large cylindrical bi-water system lithium iron phosphate battery is characterized in that the large cylindrical bi-water system lithium iron phosphate battery is formed by overlapping and winding a positive pole piece, a diaphragm and a negative pole piece; the diaphragm comprises a first diaphragm and a second diaphragm; the anode plate comprises an aluminum foil and a water-system anode coating, and the water-system anode coating comprises lithium iron phosphate, an anode conductive agent and an anode water-system binder; the negative pole piece comprises copper foil and a water-system negative pole coating, wherein the water-system negative pole coating comprises artificial graphite, a negative pole conductive agent, a negative pole water-system binder and CMC; the anode conductive agent is a carbon nano tube composite conductive slurry aqueous solution with the solid content of 2-15%; the negative electrode conductive agent is a carbon nano tube composite conductive slurry aqueous solution with the solid content of 5-20%; the anode water system binder and the cathode water system binder are 3-30% of water-based binders.
2. The large cylindrical bi-water system lithium iron phosphate battery according to claim 1, wherein the water system positive electrode coating consists of the following mass ratios: lithium iron phosphate: positive electrode conductive agent (active material): the positive electrode aqueous binder (effective substance) is 90-98:1-5: 1-5.
3. The large cylindrical bi-water system lithium iron phosphate battery of claim 1, wherein the water system negative electrode coating consists of the following mass ratios: artificial graphite: negative electrode conductive agent (effective substance): negative electrode aqueous binder (active material): CMC is 90-98:0.5-3:1-5: 0.5-3.
4. The large cylindrical dual-water-system lithium iron phosphate battery as claimed in claim 1, wherein the surface density of the water-system positive electrode coating is 300-500g/m 2 The rolling compaction density is 2.1-2.3g/cm 3 。
5. The large cylindrical dual-water system lithium iron phosphate battery as claimed in claim 1, wherein the water system negative electrode coating has an area density of 160-260g/m 2 The rolling compaction density is 1.45-1.6g/cm 3 。
6. The large cylindrical dual-water system lithium iron phosphate battery as claimed in claim 1, wherein the single large cylindrical dual-water system lithium iron phosphate battery comprises model 60200-50Ah and model 60320-100 Ah; the model 60200-50Ah and the model 60320-100Ah both have the diameter of 60mm and the height of 300mm, and the model 60200-50Ah and the model 60320-100Ah have different heights.
7. The large cylindrical bi-water system lithium iron phosphate battery of claim 1, wherein the aqueous binder is an acrylic acid multi-copolymer.
8. The method for preparing the large cylindrical bi-water system lithium iron phosphate battery according to any one of claims 1 to 7, which is characterized by comprising the following steps:
homogenizing: comprises anode homogenate and cathode homogenate; the anode homogenate is that the anode conductive agent and the anode aqueous binder are mixed uniformly, then the lithium iron phosphate is added for size mixing, then the pure water is added for uniform mixing, and the anode slurry is obtained by filtering; the negative pole homogenate is that the negative pole conductive agent and the negative pole aqueous binder are mixed evenly, then the artificial graphite and the pure water are added for size mixing, then the CMC and the pure water are added in sequence for even mixing and filtration, and the negative pole slurry is prepared;
coating and tabletting: coating the positive electrode slurry and the negative electrode slurry on the surface of the positive and negative electrode current collector, drying, rolling and slitting to obtain a positive electrode piece and a negative electrode piece;
winding: the diaphragm is manufactured by overlapping and winding the positive pole piece, the first diaphragm, the negative pole piece and the second diaphragm.
9. The preparation method of the large-column bi-aqueous lithium iron phosphate battery according to claim 8, wherein the anode homogenate comprises the steps of uniformly mixing the anode conductive agent and the anode aqueous binder until the solid content is 5-15%, adding the lithium iron phosphate, performing size mixing until the solid content is 65-85%, adding the pure water, and uniformly mixing until the solid content is 55-65%; the negative pole homogenate is that the negative pole conductive agent and the negative pole aqueous binder are mixed uniformly until the solid content is 5-15%, then the artificial graphite and the pure water are added for size mixing until the solid content is 60-75%, and then the CMC and the pure water are sequentially added for uniform mixing until the solid content is 45-55%.
10. The method for preparing a large cylindrical bi-water system lithium iron phosphate battery according to claim 8, wherein the coating sheet is coated by double-layer coating at a speed of 40 m/min, after each layer of coating is finished, the coating sheet is baked in a 40 m long oven at a temperature of 80-120 ℃, the diameter of the wound winding needle is 6-12mm, and the winding length of the positive electrode piece and the negative electrode piece is 6-8 m.
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