CN114447268A - Composite lithium manganate positive plate and lithium ion battery thereof - Google Patents
Composite lithium manganate positive plate and lithium ion battery thereof Download PDFInfo
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- CN114447268A CN114447268A CN202111596311.5A CN202111596311A CN114447268A CN 114447268 A CN114447268 A CN 114447268A CN 202111596311 A CN202111596311 A CN 202111596311A CN 114447268 A CN114447268 A CN 114447268A
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- lithium manganate
- positive electrode
- lithium
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- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 title claims abstract description 108
- 239000002131 composite material Substances 0.000 title claims abstract description 34
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 16
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 16
- 239000011248 coating agent Substances 0.000 claims abstract description 99
- 238000000576 coating method Methods 0.000 claims abstract description 99
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 claims abstract description 49
- 238000001035 drying Methods 0.000 claims abstract description 16
- 239000003792 electrolyte Substances 0.000 claims abstract description 10
- 239000006256 anode slurry Substances 0.000 claims abstract description 9
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 29
- 239000002033 PVDF binder Substances 0.000 claims description 15
- 239000002041 carbon nanotube Substances 0.000 claims description 15
- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 15
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 15
- 239000011267 electrode slurry Substances 0.000 claims description 14
- 239000010405 anode material Substances 0.000 claims description 12
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 12
- 239000006258 conductive agent Substances 0.000 claims description 11
- 239000007774 positive electrode material Substances 0.000 claims description 11
- 239000000853 adhesive Substances 0.000 claims description 8
- 230000001070 adhesive effect Effects 0.000 claims description 8
- 229910052782 aluminium Inorganic materials 0.000 claims description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 8
- 229910021389 graphene Inorganic materials 0.000 claims description 8
- 239000011888 foil Substances 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- 229910002804 graphite Inorganic materials 0.000 claims description 6
- 239000010439 graphite Substances 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 6
- -1 polytetrafluoroethylene Polymers 0.000 claims description 3
- 229910021156 KS 6 Inorganic materials 0.000 claims description 2
- 239000011230 binding agent Substances 0.000 claims description 2
- WJAKXPUSJAKPHH-UHFFFAOYSA-N buta-1,3-diene;ethene;styrene Chemical group C=C.C=CC=C.C=CC1=CC=CC=C1 WJAKXPUSJAKPHH-UHFFFAOYSA-N 0.000 claims description 2
- 238000003618 dip coating Methods 0.000 claims description 2
- 238000007765 extrusion coating Methods 0.000 claims description 2
- 229920000098 polyolefin Polymers 0.000 claims description 2
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 2
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 2
- 239000002904 solvent Substances 0.000 claims description 2
- 238000005507 spraying Methods 0.000 claims description 2
- 238000012546 transfer Methods 0.000 claims description 2
- 239000011247 coating layer Substances 0.000 claims 4
- 238000002360 preparation method Methods 0.000 abstract description 6
- 238000007086 side reaction Methods 0.000 abstract description 2
- 239000002002 slurry Substances 0.000 description 8
- 229920003048 styrene butadiene rubber Polymers 0.000 description 8
- 238000005096 rolling process Methods 0.000 description 7
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 238000003756 stirring Methods 0.000 description 5
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 4
- 239000002174 Styrene-butadiene Substances 0.000 description 4
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 4
- 239000001768 carboxy methyl cellulose Substances 0.000 description 4
- 239000011889 copper foil Substances 0.000 description 4
- 239000000839 emulsion Substances 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 239000011572 manganese Substances 0.000 description 4
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 4
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 4
- 238000011056 performance test Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical group [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 229910052744 lithium Inorganic materials 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 229910052596 spinel Inorganic materials 0.000 description 2
- 239000011029 spinel Substances 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 230000005536 Jahn Teller effect Effects 0.000 description 1
- 229910012820 LiCoO Inorganic materials 0.000 description 1
- 229910010710 LiFePO Inorganic materials 0.000 description 1
- 229910015645 LiMn Inorganic materials 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 229910021383 artificial graphite Inorganic materials 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000007323 disproportionation reaction Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000010345 tape casting Methods 0.000 description 1
- 230000009466 transformation Effects 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
- H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Crystallography & Structural Chemistry (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention belongs to the technical field of lithium ion battery positive plates, and particularly relates to a composite lithium manganate positive plate, which comprises a current collector, a lithium manganate positive coating adhered to the current collector and a lithium iron phosphate coating coated on the surface of the lithium manganate positive coating; comprises the following preparation steps: (1) preparing lithium manganate anode slurry; (2) obtaining a lithium manganate positive electrode coating pole piece; (3) preparing lithium iron phosphate anode slurry; (4) and coating the lithium iron phosphate anode slurry on a lithium manganate anode coating plate, and drying to obtain the composite lithium manganate anode plate. According to the composite lithium manganate positive plate, the inner layer is a lithium manganate positive coating, the outer layer is a lithium iron phosphate positive coating, the lithium manganate positive electrode is protected by the lithium iron phosphate coating on the outer layer of the positive electrode, the contact surface between the lithium manganate positive electrode and an electrolyte is reduced, side reactions with the electrolyte at high temperature are reduced, and the high-temperature cycle performance and the high-temperature storage performance of the battery are improved.
Description
Technical Field
The invention belongs to the technical field of lithium ion battery positive plates, and particularly relates to a composite lithium manganate positive plate and a lithium ion battery thereof.
Background
Lithium ion batteries have been widely used in the fields of portable energy sources, electric bicycles, energy storage power sources, electric vehicles and the like due to their advantages of high energy density, environmental friendliness, long service life and the like.
The main anode material of the current lithium ion battery is lithium cobaltate (LiCoO)2) Lithium manganate (LiMn)2O4) Lithium iron phosphate (LiFePO)4) And ternary, etc. The lithium manganate material has the advantages of relatively rich resources, low cost, high voltage platform, good safety performance and relatively great advantages in comprehensive performance compared with ternary lithium manganate and lithium iron phosphate. Lithium manganate has poor cycle performance and storage performance, and particularly, gas is easily generated by high-temperature storage and high-temperature cycle at high temperature, so that the battery core expands.
The reasons for the poor performance of lithium manganate are as follows: (1) and (4) dissolving manganese, wherein the manganese on the electrode is slowly dissolved in the electrolyte under the action of the electrolyte. In particular Mn at the end of discharge3+Mn at the highest concentration of ions on the particle surface3+The following disproportionation reactions occur: mn3+(s)→Mn2+(1)+Mn4+Mn produced by the reaction of(s)2+Dissolved in the electrolyte. (2) The Jahn-Teller effect causes the surface of the spinel to have phase transformation from cubic phase to tetragonal phase at the end of discharge, causes Jahn-Teller distortion, changes the crystal lattice of the spinel in volume, causes structural damage and obviously attenuates the cyclic capacity. The main current solution is to coat or dope the lithium manganate positive electrode material. The coating is mainly an oxide coating such as alumina, magnesia, etc., or an organic polymer coating. Doped with aluminum, lithium, boron, magnesium, chromium, cobalt, nickel, neodymium, etc. The coating and doping are carried out to a certain extent, so that the performance of the lithium manganate is improved, but the requirements on long circulation and high-temperature performance cannot be met.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a composite lithium manganate positive plate for improving the normal-temperature and high-temperature cycle performance and high-temperature storage performance of a lithium ion battery.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the utility model provides a compound lithium manganate positive plate, includes the mass flow body, adheres to lithium manganate positive coating on the mass flow body is in with the coating lithium iron phosphate coating on lithium manganate positive coating surface.
Preferably, the thickness of the lithium manganate positive electrode coating is 10-500 μm, and the thickness of the lithium iron phosphate coating is 2-200 μm.
Preferably, the lithium manganate positive electrode coating consists of the following components in percentage by weight: 85-99 wt% of lithium manganate anode material, 0.3-10 wt% of conductive agent and 0.5-10 wt% of adhesive.
Preferably, the lithium iron phosphate coating consists of the following components in percentage by weight: 85 wt% -99 wt% of lithium iron phosphate anode material, 0.3 wt% -10 wt% of conductive agent and 0.5 wt% -10 wt% of adhesive.
Preferably, the ratio of the surface density of the lithium manganate positive electrode coating to the surface density of the lithium iron phosphate coating is 99: 1-50: 50, preferably 95: 5-70: 30.
Preferably, the conductive agent is one or a mixture of more of conductive carbon black SP, graphite KS-6, carbon nanotubes and graphene.
Preferably, the binder is one or a mixture of polytetrafluoroethylene, polyvinylidene fluoride and styrene-butadiene ethylene.
The preparation method of the composite lithium manganate positive plate comprises the following steps:
(1) uniformly dispersing a lithium manganate positive electrode material, a conductive agent and an adhesive in a solvent to obtain lithium manganate positive electrode slurry;
(2) coating the lithium manganate positive electrode slurry on an aluminum foil, and drying to obtain a lithium manganate positive electrode coating pole piece;
(3) dispersing a lithium iron phosphate positive electrode material, a conductive agent and an adhesive in a solution to obtain lithium iron phosphate positive electrode slurry;
(4) and coating the lithium iron phosphate anode slurry on a lithium manganate anode coating plate, and drying to obtain the composite lithium manganate anode plate.
Preferably, the coating is selected from one of transfer coating, knife coating, dip coating, spray coating and extrusion coating.
Based on one general inventive concept, another object of the present invention is to protect a lithium ion battery, which comprises the above composite lithium manganate positive plate, negative plate, electrolyte and polyolefin separator. The negative plate can adopt the prior art, such as artificial graphite as the negative electrode; and assembling a battery core according to the prior art, and then injecting electrolyte to prepare the lithium ion battery.
According to the composite lithium manganate positive plate, the inner layer is a lithium manganate positive coating, the outer layer is a lithium iron phosphate positive coating, the lithium manganate positive electrode is protected by the lithium iron phosphate coating on the outer layer of the positive electrode, the contact surface between the lithium manganate positive electrode and an electrolyte is reduced, side reactions with the electrolyte at high temperature are reduced, and the high-temperature cycle performance and the high-temperature storage performance of the battery are improved.
Drawings
FIG. 1 Charge/discharge curves (0.5C/1C) of example 1 and comparative example 1;
FIG. 2 is a normal temperature cycle curve of example 1 and comparative example 1;
FIG. 3 high temperature 45 ℃ cycling profiles for example 1 and comparative example 1.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to examples. Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. It is to be understood that the following description is only illustrative of the present invention and is not to be construed as limiting the present invention.
As used herein, the terms "comprises," "comprising," "includes," "including," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.
When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or as a range of values, with a range of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted to include the ranges "1 to 4", "1 to 3", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a range of values is described herein, unless otherwise stated, the range is intended to include the endpoints thereof and all integers and fractions within the range.
Example 1
A composite lithium manganate positive plate comprises a current collector, a lithium manganate positive coating adhered to the current collector and a lithium iron phosphate coating coated on the surface of the lithium manganate positive coating;
the thickness of the lithium manganate positive electrode coating is 80 microns, and the thickness of the lithium iron phosphate coating is 50 microns;
the lithium manganate positive electrode coating comprises the following components in percentage by weight: 95.2 wt% of lithium manganate anode material, 0.7 wt% of conductive carbon black SP, 1.3 wt% of carbon nano tube and 2.8 wt% of polyvinylidene fluoride;
the lithium iron phosphate coating comprises the following components in percentage by weight: 95.2 wt% of lithium iron phosphate anode material, 0.7 wt% of carbon nano tube, 1.3 wt% of graphene and 2.8 wt% of polyvinylidene fluoride;
the ratio of the surface density of the lithium manganate positive electrode coating to the surface density of the lithium iron phosphate coating is 90: 10; the preparation method of the composite lithium manganate positive plate comprises the following steps:
(1) uniformly dispersing a lithium manganate positive electrode material, conductive carbon black SP, a carbon nano tube and polyvinylidene fluoride in N-methyl pyrrolidone to obtain lithium manganate positive electrode slurry;
(2) coating the lithium manganate positive electrode slurry on an aluminum foil through a coating machine, and drying to obtain a lithium manganate positive electrode coating pole piece;
(3) dispersing a lithium iron phosphate positive electrode material, a carbon nano tube, graphene and polyvinylidene fluoride in N-methyl pyrrolidone to obtain lithium iron phosphate positive electrode slurry;
(4) and coating the lithium iron phosphate anode slurry on a lithium manganate anode coating sheet by a coating machine, drying, rolling and slitting to obtain the composite lithium manganate anode sheet.
In the lithium ion battery in the embodiment, the composite lithium manganate positive plate of the embodiment is adopted; the negative plate is prepared by stirring 96.8 wt% of graphite, 0.6 wt% of conductive carbon black SP, 0.5 wt% of CMC (sodium carboxymethylcellulose) and 2.1 wt% of SBR (styrene butadiene rubber emulsion) into slurry, coating the slurry on a copper foil on a coating machine, and rolling for later use;
and (3) assembling the positive plate, the negative plate and the diaphragm into a 18650 battery cell according to the prior art, drying, injecting liquid, completing formation and capacity grading, and carrying out electrochemical performance testing.
Example 2
A composite lithium manganate positive plate comprises a current collector, a lithium manganate positive coating adhered to the current collector and a lithium iron phosphate coating coated on the surface of the lithium manganate positive coating;
the thickness of the lithium manganate positive electrode coating is 100 microns, and the thickness of the lithium iron phosphate coating is 25 microns;
the lithium manganate positive electrode coating comprises the following components in percentage by weight: 96.5 wt% of lithium manganate anode material, 0.8 wt% of conductive carbon black SP, 1.7 wt% of carbon nanotube and 1 wt% of polyvinylidene fluoride;
the lithium iron phosphate coating comprises the following components in percentage by weight: 96.2 wt% of lithium iron phosphate anode material, 0.7 wt% of carbon nano tube, 1.8 wt% of graphene and 1 wt% of polyvinylidene fluoride;
the ratio of the surface density of the lithium manganate positive electrode coating to the surface density of the lithium iron phosphate coating is 85: 15;
the preparation method of the composite lithium manganate positive plate comprises the following steps:
(1) uniformly dispersing a lithium manganate positive electrode material, conductive carbon black SP, a carbon nano tube and polyvinylidene fluoride in N-methyl pyrrolidone to obtain lithium manganate positive electrode slurry;
(2) coating the lithium manganate positive electrode slurry on an aluminum foil through a coating machine, and drying to obtain a lithium manganate positive electrode coating pole piece;
(3) dispersing a lithium iron phosphate positive electrode material, a carbon nano tube, graphene and polyvinylidene fluoride in N-methyl pyrrolidone to obtain lithium iron phosphate positive electrode slurry;
(4) and coating the lithium iron phosphate anode slurry on a lithium manganate anode coating sheet through a coating machine, drying, rolling and slitting to obtain the composite lithium manganate anode sheet.
In the lithium ion battery in the embodiment, the composite lithium manganate positive plate of the embodiment is adopted; the negative plate is prepared by stirring 96.8 wt% of graphite, 0.6 wt% of conductive carbon black SP, 0.5 wt% of CMC (sodium carboxymethylcellulose) and 2.1 wt% of SBR (styrene butadiene rubber emulsion) into slurry, coating the slurry on a copper foil on a coating machine, and rolling for later use;
assembling the positive plate, the negative plate and the diaphragm into a 18650 electric core according to the prior art, drying, injecting liquid, completing formation and grading, and carrying out electrochemical performance test.
Example 3
A composite lithium manganate positive plate comprises a current collector, a lithium manganate positive coating adhered to the current collector and a lithium iron phosphate coating coated on the surface of the lithium manganate positive coating;
the thickness of the lithium manganate positive electrode coating is 80 microns, and the thickness of the lithium iron phosphate coating is 50 microns;
the lithium manganate positive electrode coating comprises the following components in percentage by weight: 98 wt% of lithium manganate anode material, 0.4 wt% of conductive carbon black SP, 0.8 wt% of carbon nanotube and 0.8 wt% of polyvinylidene fluoride;
the lithium iron phosphate coating comprises the following components in percentage by weight: 98 wt% of lithium iron phosphate anode material, 0.6 wt% of carbon nano tube, 0.2 wt% of graphene and 1.2 wt% of polyvinylidene fluoride;
the ratio of the surface density of the lithium manganate positive electrode coating to the surface density of the lithium iron phosphate coating is 80: 20;
the preparation method of the composite lithium manganate positive plate comprises the following steps:
(1) uniformly dispersing a lithium manganate positive electrode material, conductive carbon black SP, a carbon nano tube and polyvinylidene fluoride in N-methyl pyrrolidone to obtain lithium manganate positive electrode slurry;
(2) coating the lithium manganate positive electrode slurry on an aluminum foil through a coating machine, and drying to obtain a lithium manganate positive electrode coating pole piece;
(3) dispersing a lithium iron phosphate positive electrode material, a carbon nano tube, graphene and polyvinylidene fluoride in N-methyl pyrrolidone to obtain lithium iron phosphate positive electrode slurry;
(4) and coating the lithium iron phosphate anode slurry on a lithium manganate anode coating sheet by a coating machine, drying, rolling and slitting to obtain the composite lithium manganate anode sheet.
In the lithium ion battery in the embodiment, the composite lithium manganate positive plate of the embodiment is adopted; the negative plate is prepared by stirring 96.8 wt% of graphite, 0.6 wt% of conductive carbon black SP, 0.5 wt% of CMC (sodium carboxymethylcellulose) and 2.1 wt% of SBR (styrene butadiene rubber emulsion) into slurry, coating the slurry on a copper foil on a coating machine, and rolling for later use;
and (3) assembling the positive plate, the negative plate and the diaphragm into a 18650 battery cell according to the prior art, drying, injecting liquid, completing formation and capacity grading, and carrying out electrochemical performance testing.
Comparative example 1
A lithium ion battery comprises the following preparation steps:
the anode is prepared by mixing and stirring 97.5 wt% of lithium manganate anode material, 0.6 wt% of carbon black conductive agent, 0.4 wt% of carbon nano tube and 1.5 wt% of polyvinylidene fluoride, coating the mixture on an aluminum foil on a coating machine, and drying the aluminum foil for later use;
the negative plate is prepared by stirring 96.8 wt% of graphite, 0.6 wt% of conductive carbon black SP, 0.5 wt% of CMC (sodium carboxymethylcellulose) and 2.1 wt% of SBR (styrene butadiene rubber emulsion) into slurry, coating the slurry on a copper foil on a coating machine, and rolling for later use;
assembling the positive plate, the negative plate and the diaphragm into a 18650 electric core according to the prior art, drying, injecting liquid, completing formation and grading, and carrying out electrochemical performance test.
The results of performance tests of the lithium ion batteries of example 1 and comparative example 1 stored at high temperature of 55 c for 7 days are shown in table 1 below.
TABLE 1 test results of high temperature storage Properties of example 1 and comparative example 1
The above embodiments are merely preferred embodiments of the present invention, and any simple modification, modification and substitution changes made to the above embodiments according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.
Claims (10)
1. The composite lithium manganate positive plate is characterized by comprising a current collector, a lithium manganate positive coating adhered to the current collector and a lithium iron phosphate coating coated on the surface of the lithium manganate positive coating.
2. The composite lithium manganate positive electrode sheet according to claim 1, wherein the thickness of said lithium manganate positive electrode coating layer is 10 to 500 μm, and the thickness of said lithium iron phosphate coating layer is 2 to 200 μm.
3. The composite lithium manganate positive electrode sheet according to claim 1, wherein said lithium manganate positive electrode coating layer is composed of the following components by weight: 85-99 wt% of lithium manganate anode material, 0.3-10 wt% of conductive agent and 0.5-10 wt% of adhesive.
4. The composite lithium manganate positive plate of claim 1, wherein said lithium iron phosphate coating layer is composed of the following components by weight: 85 wt% -99 wt% of lithium iron phosphate anode material, 0.3 wt% -10 wt% of conductive agent and 0.5 wt% -10 wt% of adhesive.
5. The composite lithium manganate positive electrode sheet according to claim 1, wherein the ratio of the area density of said lithium manganate positive electrode coating to the area density of said lithium iron phosphate coating is 99: 1 to 50: 50, preferably 95: 5 to 70: 30.
6. The composite lithium manganate positive electrode sheet according to claim 1, wherein said conductive agent is one or a mixture of several of conductive carbon black SP, graphite KS-6, carbon nanotubes and graphene.
7. The composite lithium manganate positive electrode sheet according to claim 1, wherein said binder is one or a mixture of polytetrafluoroethylene, polyvinylidene fluoride and styrene-butadiene-ethylene.
8. The method for preparing the composite lithium manganate positive electrode sheet according to any one of claims 1 to 7, comprising the steps of:
(1) uniformly dispersing a lithium manganate positive electrode material, a conductive agent and an adhesive in a solvent to obtain lithium manganate positive electrode slurry;
(2) coating the lithium manganate anode slurry on an aluminum foil, and drying to obtain a lithium manganate anode coating pole piece;
(3) dispersing a lithium iron phosphate positive electrode material, a conductive agent and an adhesive in a solution to obtain lithium iron phosphate positive electrode slurry;
(4) and coating the lithium iron phosphate anode slurry on a lithium manganate anode coating plate, and drying to obtain the composite lithium manganate anode plate.
9. The method for preparing the composite lithium manganate positive electrode sheet of claim 8, wherein the coating manner is selected from one of transfer coating, blade coating, dip coating, spray coating and extrusion coating.
10. A lithium ion battery, characterized by comprising the composite lithium manganate positive electrode sheet as set forth in any one of claims 1 to 7, a negative electrode sheet, an electrolyte and a polyolefin separator.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102544507A (en) * | 2011-12-23 | 2012-07-04 | 多氟多（焦作）新能源科技有限公司 | Lithium ion power battery positive plate and lithium ion power battery |
| CN105470496A (en) * | 2015-08-14 | 2016-04-06 | 万向A一二三系统有限公司 | Positive and negative plates for lithium-ion battery and battery employing positive and negative plates |
| CN113611839A (en) * | 2021-08-03 | 2021-11-05 | 天能帅福得能源股份有限公司 | Novel mixed system lithium-rich manganese-based positive plate and preparation method thereof, and lithium ion battery |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102544507A (en) * | 2011-12-23 | 2012-07-04 | 多氟多（焦作）新能源科技有限公司 | Lithium ion power battery positive plate and lithium ion power battery |
| CN105470496A (en) * | 2015-08-14 | 2016-04-06 | 万向A一二三系统有限公司 | Positive and negative plates for lithium-ion battery and battery employing positive and negative plates |
| CN113611839A (en) * | 2021-08-03 | 2021-11-05 | 天能帅福得能源股份有限公司 | Novel mixed system lithium-rich manganese-based positive plate and preparation method thereof, and lithium ion battery |
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