CN114784272B - Environment-friendly lithium iron phosphate battery and preparation method thereof - Google Patents
Environment-friendly lithium iron phosphate battery and preparation method thereof Download PDFInfo
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- CN114784272B CN114784272B CN202210637954.8A CN202210637954A CN114784272B CN 114784272 B CN114784272 B CN 114784272B CN 202210637954 A CN202210637954 A CN 202210637954A CN 114784272 B CN114784272 B CN 114784272B
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- 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 40
- 238000002360 preparation method Methods 0.000 title claims description 14
- 239000011267 electrode slurry Substances 0.000 claims abstract description 45
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 39
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims abstract description 34
- 239000008367 deionised water Substances 0.000 claims abstract description 28
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 28
- 238000000034 method Methods 0.000 claims abstract description 23
- 239000011230 binding agent Substances 0.000 claims abstract description 16
- 239000002002 slurry Substances 0.000 claims abstract description 16
- 239000004014 plasticizer Substances 0.000 claims abstract description 15
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 14
- 229910021389 graphene Inorganic materials 0.000 claims abstract description 14
- 229910021382 natural graphite Inorganic materials 0.000 claims abstract description 14
- 239000002904 solvent Substances 0.000 claims abstract description 14
- 239000003792 electrolyte Substances 0.000 claims abstract description 12
- 239000011248 coating agent Substances 0.000 claims description 18
- 238000000576 coating method Methods 0.000 claims description 18
- 239000006185 dispersion Substances 0.000 claims description 18
- 238000002156 mixing Methods 0.000 claims description 18
- 238000004804 winding Methods 0.000 claims description 16
- DOIRQSBPFJWKBE-UHFFFAOYSA-N dibutyl phthalate Chemical compound CCCCOC(=O)C1=CC=CC=C1C(=O)OCCCC DOIRQSBPFJWKBE-UHFFFAOYSA-N 0.000 claims description 14
- 229920001485 poly(butyl acrylate) polymer Polymers 0.000 claims description 14
- 230000008569 process Effects 0.000 claims description 13
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical group CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 10
- 238000001035 drying Methods 0.000 claims description 10
- 239000006256 anode slurry Substances 0.000 claims description 9
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical group [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 8
- 239000011889 copper foil Substances 0.000 claims description 8
- HZIJXNRGQFAGJR-UHFFFAOYSA-N 2-[2-(2-hydroxyethoxy)ethoxy]ethyl acetate Chemical compound CC(=O)OCCOCCOCCO HZIJXNRGQFAGJR-UHFFFAOYSA-N 0.000 claims description 7
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 6
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims description 6
- 229910052782 aluminium Inorganic materials 0.000 claims description 6
- 238000003490 calendering Methods 0.000 claims description 6
- 239000011888 foil Substances 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 6
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- 238000001514 detection method Methods 0.000 claims description 3
- 238000011049 filling Methods 0.000 claims description 3
- 238000010030 laminating Methods 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 3
- 239000002994 raw material Substances 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 3
- QMMJWQMCMRUYTG-UHFFFAOYSA-N 1,2,4,5-tetrachloro-3-(trifluoromethyl)benzene Chemical compound FC(F)(F)C1=C(Cl)C(Cl)=CC(Cl)=C1Cl QMMJWQMCMRUYTG-UHFFFAOYSA-N 0.000 claims description 2
- 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 claims description 2
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 2
- 150000004676 glycans Chemical class 0.000 claims description 2
- 238000006116 polymerization reaction Methods 0.000 claims description 2
- 229920001282 polysaccharide Polymers 0.000 claims description 2
- 239000005017 polysaccharide Substances 0.000 claims description 2
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 claims description 2
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 claims description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 12
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 12
- 230000008901 benefit Effects 0.000 abstract description 4
- 238000005056 compaction Methods 0.000 abstract description 4
- 230000007613 environmental effect Effects 0.000 abstract description 4
- 238000005336 cracking Methods 0.000 abstract description 3
- 230000002195 synergetic effect Effects 0.000 abstract description 3
- FKRCODPIKNYEAC-UHFFFAOYSA-N ethyl propionate Chemical compound CCOC(=O)CC FKRCODPIKNYEAC-UHFFFAOYSA-N 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 11
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 8
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 6
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 6
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 6
- 239000000853 adhesive Substances 0.000 description 4
- 230000001070 adhesive effect Effects 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 238000005096 rolling process Methods 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 229910013872 LiPF Inorganic materials 0.000 description 3
- 101150058243 Lipf gene Proteins 0.000 description 3
- 239000000654 additive Substances 0.000 description 3
- 230000000996 additive effect Effects 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 238000005524 ceramic coating Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000012046 mixed solvent Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 229920002125 Sokalan® Polymers 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000007772 electrode material Substances 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 239000004584 polyacrylic acid Substances 0.000 description 2
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 229920002319 Poly(methyl acrylate) Polymers 0.000 description 1
- QSNQXZYQEIKDPU-UHFFFAOYSA-N [Li].[Fe] Chemical compound [Li].[Fe] QSNQXZYQEIKDPU-UHFFFAOYSA-N 0.000 description 1
- -1 carboxypropylmethyl Chemical group 0.000 description 1
- 230000000747 cardiac effect Effects 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000000306 component Substances 0.000 description 1
- 239000006258 conductive agent Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000007731 hot pressing Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000003698 laser cutting Methods 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 238000004377 microelectronic Methods 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
-
- 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
-
- 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
- H01M10/36—Accumulators not provided for in groups H01M10/05-H01M10/34
-
- 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
- H01M10/36—Accumulators not provided for in groups H01M10/05-H01M10/34
- H01M10/38—Construction or manufacture
-
- 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
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Crystallography & Structural Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention belongs to the technical field of lithium ion batteries, and particularly relates to an environment-friendly lithium iron phosphate battery which comprises a positive plate, a diaphragm, a negative plate, electrolyte and a shell, and is characterized in that the positive plate comprises a positive current collector and positive slurry, and the positive slurry comprises water-based lithium iron phosphate, a binder, a plasticizer, conductive carbon black and a special solvent; the negative electrode plate comprises a negative electrode current collector and negative electrode slurry, wherein the negative electrode slurry comprises natural graphite, graphene, conductive carbon black and deionized water. The invention improves the stability of the positive electrode slurry through the synergistic effect of the plasticizer and the special solvent, solves the problem of pole piece cracking, improves the flexibility and compaction density of the pole piece, thereby improving the energy density, and the prepared lithium iron phosphate battery has strong environmental friendliness and discharge capacity of more than 85% under the condition of minus 25 ℃; the method has the advantages of convenient operation, good product uniformity, low cost, environmental protection and practical value.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to an environment-friendly lithium iron phosphate battery and a preparation method thereof.
Background
With the development of the microelectronic technology in the twentieth century, the benefits of miniaturized equipment are increased, and high requirements are put on a power supply. Lithium ion batteries have entered a large-scale practical stage. The method is applied to cardiac pacemakers at the earliest time. Since the self-discharge rate of the lithium ion power battery is extremely low, the discharge voltage is gentle. So that the pacemaker can be implanted into human body for a long time. Nowadays, lithium ion batteries are widely applied to mobile phone batteries, notebook computer batteries, electric car and electric car batteries and the like. The lithium ion power battery with high multiplying power can be applied to large buses, light electric vehicles, energy storage equipment for solar energy and wind energy power generation, satellites, aerospace and the like. From the viewpoint of comprehensive performance, the lithium ion battery is certainly the secondary battery with the most development and application prospect at present. Starting from the market of the lithium ion battery technology by Sony corporation, the development and progress of the electrode material preparation are also pushing the continuous development of the technology, and the development of the electrode material with excellent performance is directly pushing the updating of the lithium ion battery.
Currently, a lithium ion battery positive electrode slurry generally uses a fluorine-containing polymer such as polyvinylidene fluoride as a binder and NMP (N-methylpyrrolidone) as a solvent. Because the organic solvent is easy to cause environmental pollution and is easy to cause harm to the health of operators, the cost investment is required to be increased in the process of coating and drying to recycle the organic solvent, and meanwhile, the NMP cost is higher, so that the production cost of the battery is increased. Therefore, the water-based positive electrode adhesive system is researched and developed, the water-based system can avoid environmental pollution and reduce production cost, but the introduced NMP pollutes the environment, the production energy consumption is high, the slurry stability after the existing water-based iron-lithium slurry is mixed is poor, the pole piece is easy to crack and fall off powder during coating, and the pole piece has poor flexibility.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides an environment-friendly lithium iron phosphate battery with good flexibility and high compaction density of a pole piece.
In order to achieve the above purpose, the invention adopts the following technical scheme:
an environment-friendly lithium iron phosphate battery comprises a positive plate, a diaphragm, a negative plate, electrolyte and a shell, wherein the positive plate comprises a positive current collector and positive slurry, and the positive slurry comprises aqueous lithium iron phosphate, a binder, a plasticizer, conductive carbon black and a special solvent;
the negative electrode plate comprises a negative electrode current collector and negative electrode slurry, wherein the negative electrode slurry comprises natural graphite, graphene, conductive carbon black and deionized water;
the plasticizer is one of glycerol, ethylene glycol, triethylene glycol acetate, dibutyl phthalate, butyl stearate, sodium carboxymethyl cellulose and polysaccharide with the polymerization degree DP more than 1000;
the special solvent is absolute ethyl alcohol or acetone.
Preferably, the weight ratio of the aqueous lithium iron phosphate, the binder, the plasticizer, the conductive carbon black and the special solvent is 93-96:0.5-1.5:0.2-1:1.5-3:0.5-1.
Preferably, the weight ratio of the natural graphite to the graphene to the conductive carbon black to the deionized water is 90-95:1-4:1-2:3-5:90-130.
Preferably, the binder is a modified polybutylacrylate.
Preferably, the positive electrode current collector is a photo-aluminum foil with the thickness of 12-18 mu m, and the negative electrode current collector is a copper foil with the thickness of 9 mu m.
Based on one general inventive concept, another object of the present invention is to provide a method for preparing the above-mentioned environmentally friendly lithium iron phosphate battery, comprising the steps of:
(1) Preparing mixed anode slurry by an anode slurry mixing process, coating the mixed anode slurry on an anode current collector, drying, heating and calendaring to prepare an anode plate;
(2) Fully mixing raw materials of the negative electrode slurry according to a proportion to prepare mixed negative electrode slurry, coating the mixed negative electrode slurry on a negative electrode current collector, drying, heating and calendaring to prepare a negative electrode plate;
(3) Winding or laminating the positive plate, the negative plate and the isolating film to form a battery core;
(4) A plurality of electric cores are assembled together after being connected in parallel;
(5) Connecting and locking the parallel-connected battery cells with battery shell terminals or polar posts;
(6) And (3) filling the shell-in cell with liquid, sealing, and performing formation and detection to prepare the battery.
Preferably, the positive electrode slurry mixing process comprises the following steps:
s1, dispersing a binder and deionized water;
s2, adding conductive carbon black for dispersion;
s3, adding water-based lithium iron phosphate for dispersion;
s4, adding a plasticizer and a special solvent for dispersion;
s5, adding deionized water to adjust the viscosity to 2000 Pa.s-6000 mPa.s.
Compared with the prior art, the invention improves the stability of the positive electrode slurry through the synergistic effect of the plasticizer and the special solvent, solves the problem of pole piece cracking, improves the flexibility and compaction density of the pole piece, thereby improving the energy density, and the prepared lithium iron phosphate battery has strong environmental friendliness and discharge capacity of more than 85 percent under the condition of minus 25 ℃; the method has the advantages of convenient operation, good product uniformity, low cost, environmental protection, easy commercial production and wide practical value in the field of lithium batteries.
Detailed Description
The invention will be further described with reference to specific embodiments for the purpose of making the objects, technical solutions and advantages of the invention more apparent, but the invention is not limited to these examples. It should be noted that, on the premise of no conflict, new embodiments may be formed by any combination of the embodiments or technical features described below. In the present invention, unless otherwise specified, all parts and percentages are by mass, the equipment and materials employed, etc. are commercially available or are conventional in the art. The methods in the following examples are conventional in the art unless otherwise specified.
The terms "comprises," "comprising," "includes," "including," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, step, 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, step, method, article, or apparatus.
When an equivalent, concentration, or other value or parameter is expressed as a range, preferred range, or a range bounded by a list 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 ranges "1 to 5" are disclosed, the described ranges should be construed to include ranges "1 to 4", "1 to 3", "1 to 2 and 4 to 5", "1 to 3 and 5", and the like. When a numerical range is described herein, unless otherwise indicated, the range is intended to include its endpoints and all integers and fractions within the range.
Example 1
(1) Positive plate
The positive plate comprises a positive current collector (optical aluminum foil with the thickness of 15 mu m) and positive slurry, wherein the positive slurry comprises aqueous lithium iron phosphate, modified polybutyl acrylate, triethylene glycol acetate, conductive carbon black and absolute ethyl alcohol;
the weight ratio of the aqueous lithium iron phosphate to the modified polybutyl acrylate to the triethylene glycol acetate to the conductive carbon black to the absolute ethyl alcohol is 95:1.2:1:1.8:1;
the positive electrode slurry mixing process comprises the following steps of:
s1, firstly dispersing modified polybutyl acrylate and deionized water;
s2, adding conductive carbon black for dispersion;
s3, adding water-based lithium iron phosphate for dispersion;
s4, adding triethylene glycol acetate and absolute ethyl alcohol for dispersion;
s5, adding deionized water to adjust the viscosity to 4000 mPa.s.
The positive electrode slurry is uniformly coated on a 15 mu m positive electrode current collector, and the single-side coating surface density is 1.6g/100cm 2 The positive electrode sheet was rolled to a compacted density of 2.38g/cc.
(2) Negative plate
The negative electrode sheet comprises a negative electrode current collector (copper foil with the thickness of 9 mu m) and negative electrode slurry, wherein the negative electrode slurry comprises natural graphite, graphene, conductive carbon black and deionized water;
the weight ratio of the natural graphite to the graphene to the conductive carbon black to the deionized water is 92:2:1:3:120;
natural graphite (average particle size 12 μm, tap density=1.3 g/cm) 3 ) Uniformly mixing graphene, conductive carbon black and deionized water to prepare negative electrode slurry, uniformly coating the negative electrode slurry on a 9 mu m copper foil, and then drying, rolling and slitting at 110 ℃ to prepare the negative electrode plate.
(3) Preparation of winding core
And (3) winding the positive plate and the negative plate prepared in the steps (1) and (2) and the ceramic coating diaphragm (7+3) into a winding core.
(4) Preparation of electrolyte
LiPF is put into 6 (1 mol/l concentration) and additive VC (1%) were dissolved in a mixed solvent of PC (propylene carbonate)/EC (ethylene carbonate)/DMC (dimethyl carbonate)/EP (ethyl propionate) =3:2:2:3 (volume ratio) to form an electrolyte.
(5) Assembly of a battery
And (3) placing the winding core obtained in the step (3) in a shell, and then injecting the electrolyte prepared in the step (4) to prepare the environment-friendly lithium iron phosphate battery.
Example 2
(1) Positive plate
The positive plate comprises a positive current collector (optical aluminum foil with the thickness of 15 mu m) and positive slurry, wherein the positive slurry comprises aqueous lithium iron phosphate, modified polybutyl acrylate, dibutyl phthalate, conductive carbon black and acetone;
the weight ratio of the aqueous lithium iron phosphate to the modified polybutyl acrylate to the dibutyl phthalate to the conductive carbon black to the acetone is 95:1.5:1:1.5:1;
the positive electrode slurry mixing process comprises the following steps of:
s1, firstly dispersing modified polybutyl acrylate and deionized water;
s2, adding conductive carbon black for dispersion;
s3, adding water-based lithium iron phosphate for dispersion;
s4, dibutyl phthalate and acetone are added for dispersion;
s5, adding deionized water to adjust the viscosity to 5000 mPa.s.
The positive electrode slurry is uniformly coated on a 15 mu m positive electrode current collector, and the single-side coating surface density is 1.6g/100cm 2 The positive electrode sheet was rolled to a compacted density of 2.38g/cc.
(2) Negative plate
The negative electrode sheet comprises a negative electrode current collector (copper foil with the thickness of 9 mu m) and negative electrode slurry, wherein the negative electrode slurry comprises natural graphite, graphene, conductive carbon black and deionized water;
the weight ratio of the natural graphite to the graphene to the conductive carbon black to the deionized water is 95:1:1.5:4:100;
natural graphite (average particle size 12 μm, tap density=1.3 g/cm) 3 ) Uniformly mixing graphene, conductive carbon black and deionized water to prepare negative electrode slurry, uniformly coating the negative electrode slurry on a 9 mu m copper foil, and then drying, rolling and slitting at 110 ℃ to prepare the negative electrode plate.
(3) Preparation of winding core
And (3) winding the positive plate and the negative plate prepared in the steps (1) and (2) and the ceramic coating diaphragm (7+3) into a winding core.
(4) Preparation of electrolyte
LiPF is put into 6 (1 mol/l concentration) and additive VC (1%) were dissolved in a mixed solvent of PC (propylene carbonate)/EC (ethylene carbonate)/DMC (dimethyl carbonate)/EP (ethyl propionate) =3:2:2:3 (volume ratio) to form an electrolyte.
(5) Assembly of a battery
And (3) placing the winding core obtained in the step (3) in a shell, and then injecting the electrolyte prepared in the step (4) to prepare the environment-friendly lithium iron phosphate battery.
Example 3
(1) Positive plate
The positive plate comprises a positive current collector (15 mu m thick photo aluminum foil) and positive slurry, wherein the positive slurry comprises aqueous lithium iron phosphate, modified polybutyl acrylate, plasticizer, conductive carbon black and absolute ethyl alcohol;
the weight ratio of the aqueous lithium iron phosphate to the modified polybutyl acrylate to the dibutyl phthalate to the conductive carbon black to the absolute ethyl alcohol is 94:1.5:1:3:0.5;
the positive electrode slurry mixing process comprises the following steps of:
s1, firstly dispersing modified polybutyl acrylate and deionized water;
s2, adding conductive carbon black for dispersion;
s3, adding water-based lithium iron phosphate for dispersion;
s4, dibutyl phthalate and absolute ethyl alcohol are added for dispersion;
s5, adding deionized water to adjust the viscosity to 3000 mPa.s.
The positive electrode slurry is uniformly coated on a 15 mu m positive electrode current collector, and the single-side coating surface density is 1.6g/100cm 2 The positive electrode sheet was rolled to a compacted density of 2.38g/cc.
(2) Negative plate
The negative electrode sheet comprises a negative electrode current collector (copper foil with the thickness of 9 mu m) and negative electrode slurry, wherein the negative electrode slurry comprises natural graphite, graphene, conductive carbon black and deionized water;
the weight ratio of the natural graphite to the graphene to the conductive carbon black to the deionized water is 92:3:1.5:4:120.
Natural graphite (average particle size 12 μm, tap density=1.3 g/cm) 3 ) Uniformly mixing graphene, conductive carbon black and deionized water to prepare negative electrode slurry, uniformly coating the negative electrode slurry on a 9 mu m copper foil, and then drying, rolling and slitting at 110 ℃ to prepare the negative electrode plate.
(3) Preparation of winding core
And (3) winding the positive plate and the negative plate prepared in the steps (1) and (2) and the ceramic coating diaphragm (7+3) into a winding core.
(4) Preparation of electrolyte
LiPF is put into 6 (1 mol/l concentration) and additive VC (1%) were dissolved in a mixed solvent of PC (propylene carbonate)/EC (ethylene carbonate)/DMC (dimethyl carbonate)/EP (ethyl propionate) =3:2:2:3 (volume ratio) to form an electrolyte.
(5) Assembly of a battery
And (3) placing the winding core obtained in the step (3) in a shell, and then injecting the electrolyte prepared in the step (4) to prepare the environment-friendly lithium iron phosphate battery.
Comparative example 1
The binder (modified polybutyl acrylate) was replaced with polymethyl acrylate, and the other conditions and preparation method were the same as in example 1.
Comparative example 2
The plasticizer (triethylene glycol acetate) was not added, and the other conditions and the production method were the same as in example 1.
Comparative example 3
The specific solvent (absolute ethanol) was replaced with N-methylpyrrolidone (NMP), and the other conditions and preparation method were the same as in example 1.
Comparative example 4
The step of the "positive electrode slurry mixing process" is replaced with: and uniformly mixing the aqueous lithium iron phosphate, the modified polybutyl acrylate, the triethylene glycol acetate, the conductive carbon black and the absolute ethyl alcohol to prepare the negative electrode slurry.
Comparative example 5
A positive electrode sheet was prepared according to the method of example 1 in patent 201811215720.4;
selecting the median particle diameter D 50 Lithium iron phosphate of 3 μm is used as a main material of positive electrode slurry, the conductive agent is conductive carbon black, and the adhesive is the AB two-component water-based adhesive provided by the invention;
wherein the AB two-component aqueous binder comprises a component A and a component B; component A is a mixture of carboxypropylmethyl cellulose and polyacrylic acid, and component B is polyacrylic acid.
Firstly, 1722g (solid content is 5%) of adhesive A (namely a binder of a component A), 1000g of deionized water and 300g of conductive carbon black are respectively weighed and stirred for 2 hours, wherein the stirring speed is 3500rpm;
then, 7000g of positive electrode slurry main material lithium iron phosphate is added in two times, stirred for 1 hour, the stirring speed is 2000rpm, and then stirred for 3 hours at 3500rpm;
then, 289g (solid content 35%) of B glue (namely a binder of the component B) and 750g of deionized water are added after vacuumizing;
finally, stirring was carried out under vacuum for 1 hour at a stirring speed of 1000rpm. The slurry had a solids content of 67.7%, a fineness of 30 μm and a viscosity of 7600cps.
Collecting current at the positive electrodeThe single-sided coating surface density of the positive electrode slurry coated on the body (15 μm thick photo-aluminum foil) was 1.6g/m 2 The coating rate was 2m/s and the coating temperature was 80, 110, 90℃respectively.
Other conditions and preparation methods were the same as in example 1.
The lithium ion batteries of examples 1 to 3 and comparative examples 1 to 5 were each subjected to performance measurement, and the results are shown in Table 1.
TABLE 1 results of Performance measurements of lithium ion batteries of examples 1-3 and comparative examples 1-5
From the results of table 1, it can be seen from examples 1-3 and comparative example 1 that the modified polybutyl acrylate is used as the binder of the present invention, which solves the problem of cracking and dropping during coating, and improves the compaction density to improve the energy density, and the pole piece flexibility is better to improve the yield and production efficiency of rolling, laser cutting, winding and hot pressing; as can be seen from examples 1 to 3 and comparative example 2, the dispersibility and stability of the positive electrode slurry are improved by the plasticizer, thereby improving the cycle life of the battery; as can be seen from examples 1-3 and comparative example 4, the slurry mixing process of the invention has a remarkable improvement effect on improving the yield, and from examples 1-3 and comparative examples 1-5, the invention greatly improves the energy density of the lithium iron phosphate battery through the synergistic effect of a specific formula and a specific process, and simultaneously improves the discharge capacity, the cycle life and other performances of the battery, and the technical effect is remarkably improved compared with the prior art.
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 substance of the present invention are all within the scope of the technical solution of the present invention.
Claims (6)
1. The environment-friendly lithium iron phosphate battery comprises a positive plate, a diaphragm, a negative plate, electrolyte and a shell, and is characterized in that the positive plate comprises a positive current collector and positive slurry, and the positive slurry comprises aqueous lithium iron phosphate, a binder, a plasticizer, conductive carbon black and a special solvent;
the negative electrode plate comprises a negative electrode current collector and negative electrode slurry, wherein the negative electrode slurry comprises natural graphite, graphene, conductive carbon black and deionized water;
the binder is modified polybutyl acrylate;
the plasticizer is one of glycerol, ethylene glycol, triethylene glycol acetate, dibutyl phthalate, butyl stearate, sodium carboxymethyl cellulose and polysaccharide with the polymerization degree DP of more than 1000;
the special solvent is absolute ethyl alcohol;
the preparation method of the environment-friendly lithium iron phosphate battery comprises the following steps:
(1) Preparing mixed anode slurry by an anode slurry mixing process, coating the mixed anode slurry on an anode current collector, drying, heating and calendaring to prepare an anode plate;
the positive electrode slurry mixing process comprises the following steps of:
s1, dispersing a binder and deionized water;
s2, adding conductive carbon black for dispersion;
s3, adding water-based lithium iron phosphate for dispersion;
s4, adding a plasticizer and a special solvent for dispersion;
s5, adding deionized water to adjust the viscosity to 2000 Pa.s-6000 mPa.s;
(2) Fully mixing raw materials of the negative electrode slurry according to a proportion to prepare mixed negative electrode slurry, coating the mixed negative electrode slurry on a negative electrode current collector, drying, heating and calendaring to prepare a negative electrode plate;
(3) Winding or laminating the positive plate, the negative plate and the isolating film to form a battery core;
(4) A plurality of electric cores are assembled together after being connected in parallel;
(5) Connecting and locking the parallel-connected battery cells with battery shell terminals or polar posts;
(6) And (3) filling the shell-in cell with liquid, sealing, and performing formation and detection to prepare the battery.
2. The environment-friendly lithium iron phosphate battery of claim 1, wherein the weight ratio of the aqueous lithium iron phosphate, the binder, the plasticizer, the conductive carbon black and the special solvent is 93-96:0.5-1.5:0.2-1:1.5-3:0.5-1.
3. The environment-friendly lithium iron phosphate battery of claim 1, wherein the weight ratio of the natural graphite, the graphene, the conductive carbon black and the deionized water is 90-95:1-4:1-2:3-5:90-130.
4. The environment-friendly lithium iron phosphate battery according to claim 1, wherein the positive electrode current collector is a photo-aluminum foil with a thickness of 12-18 μm, and the negative electrode current collector is a copper foil with a thickness of 9 μm.
5. The method for preparing an environment-friendly lithium iron phosphate battery according to any one of claims 1 to 4, comprising the steps of:
(1) Preparing mixed anode slurry by an anode slurry mixing process, coating the mixed anode slurry on an anode current collector, drying, heating and calendaring to prepare an anode plate;
(2) Fully mixing raw materials of the negative electrode slurry according to a proportion to prepare mixed negative electrode slurry, coating the mixed negative electrode slurry on a negative electrode current collector, drying, heating and calendaring to prepare a negative electrode plate;
(3) Winding or laminating the positive plate, the negative plate and the isolating film to form a battery core;
(4) A plurality of electric cores are assembled together after being connected in parallel;
(5) Connecting and locking the parallel-connected battery cells with battery shell terminals or polar posts;
(6) And (3) filling the shell-in cell with liquid, sealing, and performing formation and detection to prepare the battery.
6. The method for preparing an environment-friendly lithium iron phosphate battery according to claim 5, wherein the positive electrode slurry mixing process comprises the following steps:
s1, dispersing a binder and deionized water;
s2, adding conductive carbon black for dispersion;
s3, adding water-based lithium iron phosphate for dispersion;
s4, adding a plasticizer and a special solvent for dispersion;
s5, adding deionized water to adjust the viscosity to 2000 Pa.s-6000 mPa.s.
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