CN117039227A - Method for directly preparing secondary battery by ultrasonic repairing of waste lithium iron phosphate - Google Patents
Method for directly preparing secondary battery by ultrasonic repairing of waste lithium iron phosphate Download PDFInfo
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- CN117039227A CN117039227A CN202310945628.8A CN202310945628A CN117039227A CN 117039227 A CN117039227 A CN 117039227A CN 202310945628 A CN202310945628 A CN 202310945628A CN 117039227 A CN117039227 A CN 117039227A
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- iron phosphate
- lithium iron
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- secondary battery
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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 133
- 238000000034 method Methods 0.000 title claims abstract description 115
- 239000002699 waste material Substances 0.000 title claims abstract description 73
- 239000000243 solution Substances 0.000 claims abstract description 57
- 239000002245 particle Substances 0.000 claims abstract description 53
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 41
- 238000001035 drying Methods 0.000 claims abstract description 41
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 41
- 238000002156 mixing Methods 0.000 claims abstract description 37
- 239000011259 mixed solution Substances 0.000 claims abstract description 35
- 239000003792 electrolyte Substances 0.000 claims abstract description 22
- 238000009210 therapy by ultrasound Methods 0.000 claims abstract description 20
- 239000007788 liquid Substances 0.000 claims abstract description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 18
- 230000008569 process Effects 0.000 claims abstract description 16
- 239000000843 powder Substances 0.000 claims abstract description 15
- 238000003756 stirring Methods 0.000 claims abstract description 15
- 239000002904 solvent Substances 0.000 claims abstract description 14
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 13
- 238000005406 washing Methods 0.000 claims abstract description 13
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 9
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 9
- 238000001291 vacuum drying Methods 0.000 claims description 27
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical group [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 claims description 26
- 229910052782 aluminium Inorganic materials 0.000 claims description 22
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 22
- 239000011888 foil Substances 0.000 claims description 21
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical group OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 20
- 230000008439 repair process Effects 0.000 claims description 19
- 239000011230 binding agent Substances 0.000 claims description 14
- 239000006258 conductive agent Substances 0.000 claims description 14
- 239000011267 electrode slurry Substances 0.000 claims description 14
- 239000000463 material Substances 0.000 claims description 14
- 238000004080 punching Methods 0.000 claims description 14
- 235000012431 wafers Nutrition 0.000 claims description 14
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 12
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 12
- NWZSZGALRFJKBT-KNIFDHDWSA-N (2s)-2,6-diaminohexanoic acid;(2s)-2-hydroxybutanedioic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O.NCCCC[C@H](N)C(O)=O NWZSZGALRFJKBT-KNIFDHDWSA-N 0.000 claims description 10
- IKDUDTNKRLTJSI-UHFFFAOYSA-N hydrazine monohydrate Substances O.NN IKDUDTNKRLTJSI-UHFFFAOYSA-N 0.000 claims description 10
- 238000000498 ball milling Methods 0.000 claims description 8
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims description 7
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 7
- 229910013872 LiPF Inorganic materials 0.000 claims description 7
- 101150058243 Lipf gene Proteins 0.000 claims description 7
- 239000004698 Polyethylene Substances 0.000 claims description 7
- 239000000919 ceramic Substances 0.000 claims description 7
- 238000005520 cutting process Methods 0.000 claims description 7
- -1 polyethylene Polymers 0.000 claims description 7
- 229920000573 polyethylene Polymers 0.000 claims description 7
- 238000007790 scraping Methods 0.000 claims description 7
- 238000002604 ultrasonography Methods 0.000 claims description 7
- 238000005303 weighing Methods 0.000 claims description 7
- 239000008367 deionised water Substances 0.000 claims description 6
- 229910021641 deionized water Inorganic materials 0.000 claims description 6
- 239000008399 tap water Substances 0.000 claims description 6
- 235000020679 tap water Nutrition 0.000 claims description 6
- 230000007547 defect Effects 0.000 abstract description 13
- 238000011084 recovery Methods 0.000 abstract description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 9
- 238000005265 energy consumption Methods 0.000 abstract description 8
- 229910010710 LiFePO Inorganic materials 0.000 abstract description 2
- 230000008901 benefit Effects 0.000 description 14
- 239000002033 PVDF binder Substances 0.000 description 10
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 10
- 230000009471 action Effects 0.000 description 8
- 239000003153 chemical reaction reagent Substances 0.000 description 8
- 238000002386 leaching Methods 0.000 description 8
- 238000011069 regeneration method Methods 0.000 description 7
- 238000000926 separation method Methods 0.000 description 7
- 239000000126 substance Substances 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 238000002848 electrochemical method Methods 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- 238000000746 purification Methods 0.000 description 5
- 239000002002 slurry Substances 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 4
- 230000000630 rising effect Effects 0.000 description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 3
- 238000000137 annealing Methods 0.000 description 3
- 239000010405 anode material Substances 0.000 description 3
- 238000003912 environmental pollution Methods 0.000 description 3
- 238000001704 evaporation Methods 0.000 description 3
- 238000000024 high-resolution transmission electron micrograph Methods 0.000 description 3
- 229910001416 lithium ion Inorganic materials 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 239000007774 positive electrode material Substances 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000001027 hydrothermal synthesis Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 229910010707 LiFePO 4 Inorganic materials 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 238000010000 carbonizing Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000002173 high-resolution transmission electron microscopy Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 229910000398 iron phosphate Inorganic materials 0.000 description 1
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000010532 solid phase synthesis reaction Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000007847 structural defect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000009469 supplementation Effects 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
- 239000002351 wastewater Substances 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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/54—Reclaiming serviceable parts of waste 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
- H01M10/052—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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4242—Regeneration of electrolyte or reactants
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The application discloses a method for directly preparing a secondary battery by ultrasonic repairing of waste lithium iron phosphate, which comprises the following steps: s1, mixing a reducing agent, lithium salt and a solvent to prepare a repairing solution; s2, adding waste lithium iron phosphate powder into the repairing solution, and stirring and mixing to obtain a mixed solution; s3, placing the uniformly mixed liquid into an ultrasonic cell crusher for two-stage ultrasonic treatment; s4, carrying out centrifugal water washing on the solution subjected to ultrasonic treatment; s5, putting the centrifuged solution into a drying oven for drying to obtain repaired lithium iron phosphate particles; s6, preparing a positive electrode plate by using the repaired lithium iron phosphate particles; step S7, using the lithium sheet as a counter electrode and a positive electrodeThe sheet, electrolyte and separator are assembled into a secondary battery. Through the design, the application uses N 2 H 4 ·H 2 O is a reducing agent, and the waste LiFePO is repaired in a short time by a high-power ultrasonic process 4 Li in (B) + The vacancy defect and the Li/Fe inversion defect realize the rapid low-energy-consumption recovery of the waste lithium iron phosphate.
Description
Technical Field
The application belongs to the field of battery preparation, and particularly relates to a method for directly preparing a secondary battery by ultrasonic repair of waste lithium iron phosphate.
Background
The lithium iron phosphate battery is widely used in the fields of new energy automobiles, energy storage power stations and the like due to the advantages of good thermal stability, high safety, long cycle life, low cost and the like. However, with the prosperity of the lithium iron phosphate battery market, the potential battery recycling problem is also increasing, and if the retired battery is not handled in time, serious resource waste and environmental pollution are caused. At present, the recovery method of waste lithium iron phosphate mainly comprises a selective lithium leaching method and a direct regeneration method.
The selective lithium leaching means that Li is recovered from waste lithium iron phosphate material on the premise of incompletely destroying the crystal structure of lithium iron phosphate, and Fe and P are FePO 4 The form is recycled, the method consumes less chemical reagent, and the recycling cost is lower; however, a large amount of acid-base reagents are needed in the recovery process, and a large amount of waste gas and waste water which are unfavorable for human bodies are easily generated.
Direct regeneration is mainly based on the supplementation of missing active Li + And repairing the structural defect, so as to recover the electrochemical activity of the positive electrode material, and the regenerated positive electrode material can be directly used for manufacturing the lithium ion battery. The direct regeneration method does not need to go through complicated metal element separation and purification processes, so that the consumption of chemical reagents and energy sources can be obviously reduced, and the economic benefit is improved to the greatest extent. The existing preparation method of lithium iron phosphate is a solid-phase method, the reaction conditions are harsh, and a long-time nitrogen environment is required even under normal pressure, so that the method has a large distance from commercial production, and therefore, the development of a liquid-phase regeneration method with low cost, high efficiency, simplicity and easiness in operation is imperative.
The existing recovery method of waste lithium iron phosphate mainly comprises an electrochemical method and a selective lithium leaching method. The electrochemical method is as disclosed in Chinese patent CN116315229A, and the method for recovering lithium from waste lithium ion batteries to cooperatively repair the lithium iron phosphate material comprises the following main steps: pretreating a waste positive plate, and then carrying out constant-current electrolysis on the pretreated positive plate and a waste lithium iron phosphate positive electrode by an electrochemical method to repair a lithium iron phosphate material; and (3) drying, ball milling, roasting and the like the repaired material to finally obtain the regenerated lithium iron phosphate positive electrode material. The method can carry out lithium supplementing, repairing and regenerating on the waste lithium iron phosphate material, thereby preparing a new lithium iron phosphate electrode material; and useful materials such as byproduct iron phosphate after lithium removal are obtained. But the operation process is complex, the yield is not high, and the influence caused by the inversion defect formed in the circulation process is ignored.
The selective lithium leaching method is a method for recycling waste lithium iron phosphate anode materials, which is disclosed in Chinese patent CN112429752A, and mainly comprises the following steps: s1, dissolving aluminum of a waste lithium iron phosphate anode material by alkali, and collecting solids; s2, dissolving the solid in the step S1 by sulfuric acid, performing first evaporation concentration on the solution obtained by solid-liquid separation, and cooling and crystallizing to obtain liquid and crystals; s3, evaporating and concentrating the liquid obtained in the step S2 for the second time, separating solid from liquid to obtain liquid and solid, and removing impurities and carbonizing the solid; and S4, evaporating and concentrating the liquid obtained in the step S3 for the third time. Although the method can realize the separation of three elements of lithium, iron and phosphorus in the waste lithium iron phosphate material, the process flow is complex, and the reagents such as sodium hydroxide, concentrated sulfuric acid and the like are used, so that the method is extremely easy to pollute the environment.
At present, the repairing method of the waste lithium iron phosphate mainly comprises an electrochemical method and a selective lithium leaching method, but the two methods are complex in operation, high in energy consumption, long in time consumption and large in environmental pollution. In order to solve the problems, a new method for repairing the waste lithium iron phosphate is urgently needed.
Disclosure of Invention
Aiming at the problems that the current method for repairing the waste lithium iron phosphate mainly comprises an electrochemical method and a selective lithium leaching method, but the two methods are complex in operation, high in energy consumption, long in time consumption and large in environmental pollution, the application designs a method for directly preparing a secondary battery by repairing the waste lithium iron phosphate by using ultrasonic waves so as to realize the rapid low-energy recovery of the waste lithium iron phosphate.
A method for directly preparing a secondary battery by ultrasonic repairing of waste lithium iron phosphate comprises the following steps:
s1, mixing a reducing agent, lithium salt and a solvent to prepare a repairing solution;
s2, adding waste lithium iron phosphate powder into the repairing solution, and stirring and mixing to obtain a mixed solution;
s3, placing the mixed solution which is uniformly mixed into ultrasonic equipment for two-section ultrasonic treatment;
s4, carrying out centrifugal water washing on the solution subjected to ultrasonic treatment;
s5, putting the centrifuged solution into a drying oven for drying to obtain repaired lithium iron phosphate particles;
s6, preparing a positive electrode plate by using the repaired lithium iron phosphate particles;
and S7, using the lithium sheet as a counter electrode, and assembling the lithium sheet, the positive electrode sheet, the electrolyte and the diaphragm into the secondary battery.
Preferably, the reducing agent in the step S1 is hydrazine hydrate, the lithium salt is lithium chloride, and the solvent is ethylene glycol.
Preferably, in the primary solution prepared by lithium chloride and glycol, li + The concentration is 0.5-2.0M.
Preferably, the adding amount of the hydrazine hydrate in the repairing solution is 0.5-2.0 mL.
Preferably, in the step S2, the stirring and mixing method is that stirring is carried out for 10min at 500rpm/min at room temperature.
Preferably, the specific method of step S3 includes:
step S301, transferring the mixed solution into a box body of an ultrasonic cell crusher, extending an amplitude transformer into the mixed solution below 1cm of the liquid level, and setting the ultrasonic power to be 500W;
step S302, placing a 50mL small beaker filled with mixed liquid in a 500mL large beaker filled with tap water, and setting the ultrasonic process as two sections and the ultrasonic time as 25 minutes; then left to stand for 10min, followed by an additional 25min of ultrasound.
Preferably, the specific method of step S4 is as follows:
s401, separating lithium iron phosphate particles from the mixed solution after the second ultrasonic treatment in a centrifugal way;
and S402, repeatedly washing with deionized water and ethanol to remove residual lithium chloride and hydrazine hydrate on the surfaces of the lithium iron phosphate particles.
Preferably, the specific method of step S5 is as follows: and (3) putting the lithium iron phosphate particles obtained in the step (S4) into a vacuum drying oven, and drying for 12 hours at the temperature of 60 ℃ to obtain the repaired dry lithium iron phosphate particles.
Preferably, the specific method of step S6 includes:
step S601, weighing lithium iron phosphate particles, a conductive agent and a binder according to the mass ratio of 8:1:1, and adding the lithium iron phosphate particles, the conductive agent and the binder into a ball milling tank;
step S602, adding a proper amount of N-methyl pyrrolidone, and uniformly mixing to form electrode slurry;
and S603, uniformly scraping the electrode slurry on the surface of the aluminum foil by using a 120 mu m scraper, and then placing the aluminum foil into a 80 ℃ blast drying oven for drying for 8 hours, and obtaining the positive electrode plate after the aluminum foil is completely dried.
Preferably, the specific method of step S7 includes:
step S701, compacting the positive electrode plate by using a roller press, cutting the positive electrode plate into positive electrode wafers with the diameter of 14mm by using a sheet punching machine, and putting the cut positive electrode wafers into a vacuum drying oven at the temperature of 60 ℃ for drying for 12 hours for later use;
step S702, mixing ethylene carbonate and diethyl carbonate according to a mass ratio of 1:1 under the condition of room temperature, and adding LiPF with a concentration of 1mol/L 6 Fully mixing and standing for 24 hours to obtain electrolyte;
step S703, punching the ceramic-coated polyethylene material into a circular sheet with the diameter of 16mm, transferring the circular sheet into a vacuum drying oven with the temperature of 55 ℃, and vacuum drying for 24 hours to obtain a diaphragm;
step S704, using the lithium sheet as a counter electrode, and assembling the lithium sheet with the electrolyte obtained in step S702, the positive electrode sheet obtained in step S6, and the separator obtained in step S703 into a secondary battery.
The application has the following advantages and effects:
1. the application relates to a method for directly preparing a secondary battery by ultrasonic repairing of waste lithium iron phosphate, which uses N by a direct regeneration method 2 H 4 ·H 2 O is used as a reducing agent, and Li in the waste lithium iron phosphate is repaired in a short time through a high-power ultrasonic process + Compared with the common hydrothermal method and the selective lithium leaching method, the ultrasonic method has the advantages of short time and low energy consumption, can be performed at room temperature, greatly improves the recovery efficiency, and has more excellent performance after repairing.
2. The method for directly preparing the secondary battery by ultrasonic repairing of the waste lithium iron phosphate, which is designed by the application, utilizes ultrasonic cavitation bubble collapse to generate local high-temperature, high-pressure and strong shock wave jet flow, and provides a very special physical and chemical environment for repairing the waste lithium iron phosphate, so that the effect of rapidly and efficiently repairing the waste lithium iron phosphate can be achieved, and the method also has the advantages of simplicity in operation, short reaction time and low energy consumption.
3. The application relates to a method for directly preparing a secondary battery by ultrasonic repairing of waste lithium iron phosphate, which repairs Li in the waste lithium iron phosphate by ultrasonic reaction + The vacancy defect and the Li/Fe inversion defect can be eliminated without short-time annealing and complicated metal element separation and purification processes, so that the consumption of chemical reagents and energy sources can be obviously reduced, the energy consumption is greatly reduced, the recovery process is simplified, and the economic benefit is improved to the greatest extent.
The foregoing description is only an overview of the present application, and is intended to provide a better understanding of the technical means of the present application, so that the present application may be practiced according to the teachings of the present specification, and so that the above-mentioned and other objects, features and advantages of the present application may be better understood, and the following detailed description of the preferred embodiments of the present application will be presented in conjunction with the accompanying drawings.
The above and other objects, advantages and features of the present application will become more apparent to those skilled in the art from the following detailed description of the specific embodiments of the present application when taken in conjunction with the accompanying drawings.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. Like elements or portions are generally identified by like reference numerals throughout the several figures. In the drawings, elements or portions thereof are not necessarily drawn to scale.
FIG. 1 is a flow chart of a method for directly preparing a secondary battery by ultrasonically repairing waste lithium iron phosphate;
FIG. 2 is an XRD spectrum of lithium iron phosphate before and after repair provided by the application;
FIG. 3 is an HRTEM diagram of the waste lithium iron phosphate provided by the application;
fig. 4 is an HRTEM image of the ultrasonically repaired lithium iron phosphate provided by the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. In the following description, specific details such as specific configurations and components are provided merely to facilitate a thorough understanding of embodiments of the application. It will therefore be apparent to those skilled in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the application. In addition, descriptions of well-known functions and constructions are omitted in the embodiments for clarity and conciseness.
It should be appreciated that reference throughout this specification to "one embodiment" or "this embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, the appearances of the "one embodiment" or "this embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
Furthermore, the present application may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
The term "and/or" is herein merely an association relationship describing an associated object, meaning that there may be three relationships, e.g., a and/or B, may represent: the terms "/and" herein describe another associative object relationship, indicating that there may be two relationships, e.g., a/and B, may indicate that: the character "/" herein generally indicates that the associated object is an "or" relationship.
The term "at least one" is herein merely an association relation describing an associated object, meaning that there may be three kinds of relations, e.g., at least one of a and B may represent: a exists alone, A and B exist together, and B exists alone.
It is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprise," "include," or any other variation thereof, are intended to cover a non-exclusive inclusion.
Example 1
The present embodiment mainly describes a first method for directly preparing a secondary battery by ultrasonic repairing of waste lithium iron phosphate, please refer to fig. 1, specifically including:
s1, mixing a reducing agent, lithium salt and a solvent to prepare a repairing solution;
s2, adding waste lithium iron phosphate powder into the repairing solution, and stirring and mixing to obtain a mixed solution;
s3, placing the mixed solution which is uniformly mixed into ultrasonic equipment for two-section ultrasonic treatment;
s4, carrying out centrifugal water washing on the solution subjected to ultrasonic treatment;
s5, putting the centrifuged solution into a drying oven for drying to obtain repaired lithium iron phosphate particles;
s6, preparing a positive electrode plate by using the repaired lithium iron phosphate particles;
and S7, using the lithium sheet as a counter electrode, and assembling the lithium sheet, the positive electrode sheet, the electrolyte and the diaphragm into the secondary battery.
Further, in the step S1, the method for preparing the repair solution includes: first, 1.2717LiCl and 30mL of 50vol% glycol solution were prepared as Li + 1M solution was initially added followed by gradual addition of 1.5. 1.5mLN 2 H 4 ·H 2 O, said N 2 H 4 ·H 2 The addition of O needs to be carried out in step S2.
Further, the specific method in step S2 is as follows: 1g of waste lithium iron phosphate powder is weighed and placed in the prepared primary solution, the powder is completely dispersed under the action of ultrasonic wave, and then 1.5mL of N is added dropwise into the solution while stirring 2 H 4 ·H 2 O, then stirred at 500rpm/min at room temperature for 10min to obtain a mixed solution.
Further, the specific method in step S3 is as follows:
step S301, transferring the mixed solution into a box body of an ultrasonic cell crusher, extending an amplitude transformer into the mixed solution below 1cm of the liquid level, and setting the ultrasonic power to be 500W;
step S302, in order to prevent the temperature from rising severely in the ultrasonic process, placing a 50mL small beaker filled with mixed liquid in a 500mL large beaker filled with tap water, and setting the ultrasonic process to be two-stage, wherein the ultrasonic time is set to be 25min; then left to stand for 10min, followed by an additional 25min of ultrasound.
Further, the specific method in step S4 is as follows:
s401, separating lithium iron phosphate particles from the mixed solution after the second ultrasonic treatment in a centrifugal way;
and S402, repeatedly washing with deionized water and ethanol to remove residual lithium chloride and hydrazine hydrate on the surfaces of the lithium iron phosphate particles.
Further, the specific method in step S5 is as follows: and (2) placing the lithium iron phosphate particles obtained in the step (S4) into a vacuum drying oven, and drying for 12 hours to obtain repaired dried lithium iron phosphate particles, wherein an XRD spectrum of the lithium iron phosphate before repair is shown in FIG. 2. For HRTEM images of spent lithium iron phosphate, please refer to fig. 3. Please refer to fig. 4 for HRTEM images of lithium iron phosphate after ultrasonic repair.
Further, the specific method of step S6 includes:
step S601, weighing lithium iron phosphate particles, a conductive agent (conductive carbon black, SP) and a binder (polyvinylidene fluoride, PVDF) according to the mass ratio of 8:1:1, and adding the lithium iron phosphate particles, the conductive agent and the binder into a ball milling tank;
step S602, adding a proper amount of solvent (N-methyl pyrrolidone, NMP) to ensure the viscosity of the electrode slurry, and uniformly mixing various substances to form a slurry with fluidity;
and S603, uniformly scraping the electrode slurry on the surface of the aluminum foil by using a 120 mu m scraper, and then placing the aluminum foil into a 80 ℃ blast drying oven for drying for 8 hours, and obtaining the positive electrode plate after the aluminum foil is completely dried.
Further, the specific method of step S7 includes:
step S701, compacting the positive electrode plate by using a roller press, cutting the positive electrode plate into positive electrode wafers with the diameter of 14mm by using a sheet punching machine, and putting the cut positive electrode wafers into a vacuum drying oven at the temperature of 60 ℃ for drying for 12 hours for later use;
step S702, mixing ethylene carbonate and diethyl carbonate according to a mass ratio of 1:1 under the condition of room temperature, and adding LiPF with a concentration of 1mol/L 6 Fully mixing and standing for 24 hours to obtain electrolyte;
step S703, punching the ceramic-coated polyethylene material into a circular sheet with the diameter of 16mm, transferring the circular sheet into a vacuum drying oven with the temperature of 55 ℃, and vacuum drying for 24 hours to obtain a diaphragm;
and step 704, in a glove box with the water and oxygen contents being less than 0.1ppm, using the lithium sheet as a counter electrode, and assembling the lithium sheet, the electrolyte obtained in the step 702, the positive electrode sheet obtained in the step 6 and the separator obtained in the step 703 into a secondary battery.
The method for repairing the waste lithium iron phosphate is a direct regeneration method, does not need to undergo complicated metal element separation and purification processes, can obviously reduce the consumption of chemical reagents and energy sources, and improves the economic benefit to the maximum extent.
Example 2
Based on the embodiment 1, the embodiment mainly describes a second method for directly preparing a secondary battery by ultrasonically repairing waste lithium iron phosphate, which specifically comprises the following steps:
s1, mixing a reducing agent, lithium salt and a solvent to prepare a repairing solution;
s2, adding waste lithium iron phosphate powder into the repairing solution, and stirring and mixing to obtain a mixed solution;
s3, placing the mixed solution which is uniformly mixed into ultrasonic equipment for two-section ultrasonic treatment;
s4, carrying out centrifugal water washing on the solution subjected to ultrasonic treatment;
s5, putting the centrifuged solution into a drying oven for drying to obtain repaired lithium iron phosphate particles;
s6, preparing a positive electrode plate by using the repaired lithium iron phosphate particles;
and S7, using the lithium sheet as a counter electrode, and assembling the lithium sheet, the positive electrode sheet, the electrolyte and the diaphragm into the secondary battery.
Further, in the step S1, the method for preparing the repair solution includes: first, 0.763g LiCl and 30mL of a 50vol% ethylene glycol solution were prepared as Li + The initial solution of 0.6M concentration was then gradually added to 1mLN 2 H 4 ·H 2 O, said N 2 H 4 ·H 2 The addition of O needs to be carried out in step S2.
Further, the specific method in step S2 is as follows: 1g of waste lithium iron phosphate powder is weighed and placed in the prepared primary solution, and the powder is completely dispersed under the action of ultrasonic, and then stirred1mL of N was added dropwise to the solution while stirring 2 H 4 ·H 2 O, then stirred at 500rpm/min at room temperature for 10min to obtain a mixed solution.
Further, the specific method in step S3 is as follows:
step S301, transferring the mixed solution into a box body of an ultrasonic cell crusher, extending an amplitude transformer into the mixed solution below 1cm of the liquid level, and setting the ultrasonic power to be 500W;
step S302, in order to prevent the temperature from rising severely in the ultrasonic process, placing a 50mL small beaker filled with mixed liquid in a 500mL large beaker filled with tap water, and setting the ultrasonic process to be two-stage, wherein the ultrasonic time is set to be 25min; then left to stand for 10min, followed by an additional 25min of ultrasound.
Further, the specific method in step S4 is as follows:
s401, separating lithium iron phosphate particles from the mixed solution after the second ultrasonic treatment in a centrifugal way;
and S402, repeatedly washing with deionized water and ethanol to remove residual lithium chloride and hydrazine hydrate on the surfaces of the lithium iron phosphate particles.
Further, the specific method in step S5 is as follows: and (3) putting the lithium iron phosphate particles obtained in the step (S4) into a vacuum drying oven, and drying for 12 hours at the temperature of 60 ℃ to obtain the repaired dry lithium iron phosphate particles.
Further, the specific method of step S6 includes:
step S601, weighing lithium iron phosphate particles, a conductive agent (conductive carbon black, SP) and a binder (polyvinylidene fluoride, PVDF) according to the mass ratio of 8:1:1, and adding the lithium iron phosphate particles, the conductive agent and the binder into a ball milling tank;
step S602, adding a proper amount of solvent (N-methyl pyrrolidone, NMP) to ensure the viscosity of the electrode slurry, and uniformly mixing various substances to form a slurry with fluidity;
and S603, uniformly scraping the electrode slurry on the surface of the aluminum foil by using a 120 mu m scraper, and then placing the aluminum foil into a 80 ℃ blast drying oven for drying for 8 hours, and obtaining the positive electrode plate after the aluminum foil is completely dried.
Further, the specific method of step S7 includes:
step S701, compacting the positive electrode plate by using a roller press, cutting the positive electrode plate into positive electrode wafers with the diameter of 14mm by using a sheet punching machine, and putting the cut positive electrode wafers into a vacuum drying oven at the temperature of 60 ℃ for drying for 12 hours for later use;
step S702, mixing ethylene carbonate and diethyl carbonate according to a mass ratio of 1:1 under the condition of room temperature, and adding LiPF with a concentration of 1mol/L 6 Fully mixing and standing for 24 hours to obtain electrolyte;
step S703, punching the ceramic-coated polyethylene material into a circular sheet with the diameter of 16mm, transferring the circular sheet into a vacuum drying oven with the temperature of 55 ℃, and vacuum drying for 24 hours to obtain a diaphragm;
and step 704, in a glove box with the water and oxygen contents being less than 0.1ppm, using the lithium sheet as a counter electrode, and assembling the lithium sheet, the electrolyte obtained in the step 702, the positive electrode sheet obtained in the step 6 and the separator obtained in the step 703 into a secondary battery.
The application relates to a method for directly preparing a secondary battery by ultrasonic repairing of waste lithium iron phosphate, which uses N by a direct regeneration method 2 H 4 ·H 2 O is used as a reducing agent, and Li in the waste lithium iron phosphate is repaired in a short time through a high-power ultrasonic process + Compared with the common hydrothermal method and the selective lithium leaching method, the two-stage ultrasonic method has the advantages that the time required by the vacancy defect and the Li/Fe inversion defect is shorter, the recovery efficiency is greatly improved, and the performance of the repaired anode material is more excellent.
Example 3
Based on the embodiment 1, the embodiment mainly describes a third method for directly preparing the secondary battery by ultrasonically repairing the waste lithium iron phosphate, which specifically comprises the following steps:
s1, mixing a reducing agent, lithium salt and a solvent to prepare a repairing solution;
s2, adding waste lithium iron phosphate powder into the repairing solution, and stirring and mixing to obtain a mixed solution;
s3, placing the mixed solution which is uniformly mixed into ultrasonic equipment for two-section ultrasonic treatment;
s4, carrying out centrifugal water washing on the solution subjected to ultrasonic treatment;
s5, putting the centrifuged solution into a drying oven for drying to obtain repaired lithium iron phosphate particles;
s6, preparing a positive electrode plate by using the repaired lithium iron phosphate particles;
and S7, using the lithium sheet as a counter electrode, and assembling the lithium sheet, the positive electrode sheet, the electrolyte and the diaphragm into the secondary battery.
Further, in the step S1, the method for preparing the repair solution includes: first, 1.2717g LiCl and 30mL of a 50vol% glycol solution were prepared as Li + 1M solution was initially added followed by gradual addition of 1mLN 2 H 4 ·H 2 O, said N 2 H 4 ·H 2 The addition of O needs to be carried out in step S2.
Further, the specific method in step S2 is as follows: 1g of waste lithium iron phosphate powder is weighed and placed in the prepared primary solution, the powder is completely dispersed under the action of ultrasonic wave, and then 1mL of N is added dropwise into the solution while stirring 2 H 4 ·H 2 O, then stirred at 500rpm/min at room temperature for 10min to obtain a mixed solution.
Further, the specific method in step S3 is as follows:
step S301, transferring the mixed solution into a box body of an ultrasonic cell crusher, extending an amplitude transformer into the mixed solution below 1cm of the liquid level, and setting the ultrasonic power to be 500W;
step S302, in order to prevent the temperature from rising severely in the ultrasonic process, placing a 50mL small beaker filled with mixed liquid in a 500mL large beaker filled with tap water, and setting the ultrasonic process to be two-stage, wherein the ultrasonic time is set to be 25min; then left to stand for 10min, followed by an additional 25min of ultrasound.
Further, the specific method in step S4 is as follows:
s401, separating lithium iron phosphate particles from the mixed solution after the second ultrasonic treatment in a centrifugal way;
and S402, repeatedly washing with deionized water and ethanol to remove residual lithium chloride and hydrazine hydrate on the surfaces of the lithium iron phosphate particles.
Further, the specific method in step S5 is as follows: and (3) putting the lithium iron phosphate particles obtained in the step (S4) into a vacuum drying oven, and drying at 60 ℃ for 12 hours to obtain the repaired dry lithium iron phosphate particles.
Further, the specific method of step S6 includes:
step S601, weighing lithium iron phosphate particles, a conductive agent (conductive carbon black, SP) and a binder (polyvinylidene fluoride, PVDF) according to the mass ratio of 8:1:1, and adding the lithium iron phosphate particles, the conductive agent and the binder into a ball milling tank;
step S602, adding a proper amount of solvent (N-methyl pyrrolidone, NMP) to ensure the viscosity of the electrode slurry, and uniformly mixing various substances to form a slurry with fluidity;
and S603, uniformly scraping the electrode slurry on the surface of the aluminum foil by using a 120 mu m scraper, and then placing the aluminum foil into a 80 ℃ blast drying oven for drying for 8 hours, and obtaining the positive electrode plate after the aluminum foil is completely dried.
Further, the specific method of step S7 includes:
step S701, compacting the positive electrode plate by using a roller press, cutting the positive electrode plate into positive electrode wafers with the diameter of 14mm by using a sheet punching machine, and putting the cut positive electrode wafers into a vacuum drying oven at the temperature of 60 ℃ for drying for 12 hours for later use;
step S702, mixing ethylene carbonate and diethyl carbonate according to a mass ratio of 1:1 under the condition of room temperature, and adding LiPF with a concentration of 1mol/L 6 Fully mixing and standing for 24 hours to obtain electrolyte;
step S703, punching the ceramic-coated polyethylene material into a circular sheet with the diameter of 16mm, transferring the circular sheet into a vacuum drying oven with the temperature of 55 ℃, and vacuum drying for 24 hours to obtain a diaphragm;
and step 704, in a glove box with the water and oxygen contents being less than 0.1ppm, using the lithium sheet as a counter electrode, and assembling the lithium sheet, the electrolyte obtained in the step 702, the positive electrode sheet obtained in the step 6 and the separator obtained in the step 703 into a secondary battery.
The method for directly preparing the secondary battery by ultrasonic repairing of the waste lithium iron phosphate, which is designed by the application, utilizes ultrasonic cavitation bubble collapse to generate local high-temperature, high-pressure and strong shock wave jet flow, and provides a very special physical and chemical environment for repairing the waste lithium iron phosphate, so that the effect of rapidly and efficiently repairing the waste lithium iron phosphate can be achieved, and the method also has the advantages of simplicity in operation and short reaction time.
Example 4
Based on the embodiment 1, the embodiment mainly describes a fourth method for directly preparing the secondary battery by ultrasonically repairing the waste lithium iron phosphate, which specifically comprises the following steps:
s1, mixing a reducing agent, lithium salt and a solvent to prepare a repairing solution;
s2, adding waste lithium iron phosphate powder into the repairing solution, and stirring and mixing to obtain a mixed solution;
s3, placing the mixed solution which is uniformly mixed into ultrasonic equipment for two-section ultrasonic treatment;
s4, carrying out centrifugal water washing on the solution subjected to ultrasonic treatment;
s5, putting the centrifuged solution into a drying oven for drying to obtain repaired lithium iron phosphate particles;
s6, preparing a positive electrode plate by using the repaired lithium iron phosphate particles;
and S7, using the lithium sheet as a counter electrode, and assembling the lithium sheet, the positive electrode sheet, the electrolyte and the diaphragm into the secondary battery.
Further, in the step S1, the method for preparing the repair solution includes: 1.9076g LiCl and 30mL of 50vol% glycol solution were first prepared as Li + 1.5M solution was initially added followed by gradual addition of 1.5mL N 2 H 4 ·H 2 O, said N 2 H 4 ·H 2 The addition of O needs to be carried out in step S2.
Further, the specific method in step S2 is as follows: 1g of waste lithium iron phosphate powder is weighed and placed in the prepared primary solution, the powder is completely dispersed under the action of ultrasonic wave, and then 1.5mL of N is added dropwise into the solution while stirring 2 H 4 ·H 2 O, then stirred at 500rpm/min at room temperature for 10min to obtain a mixed solution.
Further, the specific method in step S3 is as follows:
step S301, transferring the mixed solution into a box body of an ultrasonic cell crusher, extending an amplitude transformer into the mixed solution below 1cm of the liquid level, and setting the ultrasonic power to be 500W;
step S302, in order to prevent the temperature from rising severely in the ultrasonic process, placing a 50mL small beaker filled with mixed liquid in a 500mL large beaker filled with tap water, and setting the ultrasonic process to be two-stage, wherein the ultrasonic time is set to be 25min; then left to stand for 10min, followed by an additional 25min of ultrasound.
Further, the specific method in step S4 is as follows:
s401, separating lithium iron phosphate particles from the mixed solution after the second ultrasonic treatment in a centrifugal way;
and S402, repeatedly washing with deionized water and ethanol to remove residual lithium chloride and hydrazine hydrate on the surfaces of the lithium iron phosphate particles.
Further, the specific method in step S5 is as follows: and (3) putting the lithium iron phosphate particles obtained in the step (S4) into a vacuum drying oven to be dried at 60 ℃ for 12 hours, and obtaining the repaired dry lithium iron phosphate particles.
Further, the specific method of step S6 includes:
step S601, weighing lithium iron phosphate particles, a conductive agent (conductive carbon black, SP) and a binder (polyvinylidene fluoride, PVDF) according to the mass ratio of 8:1:1, and adding the lithium iron phosphate particles, the conductive agent and the binder into a ball milling tank;
step S602, adding a proper amount of solvent (N-methyl pyrrolidone, NMP) to ensure the viscosity of the electrode slurry, and uniformly mixing various substances to form a slurry with fluidity;
and S603, uniformly scraping the electrode slurry on the surface of the aluminum foil by using a 120 mu m scraper, and then placing the aluminum foil into a 80 ℃ blast drying oven for drying for 8 hours, and obtaining the positive electrode plate after the aluminum foil is completely dried.
Further, the specific method of step S7 includes:
step S701, compacting the positive electrode plate by using a roller press, cutting the positive electrode plate into positive electrode wafers with the diameter of 14mm by using a sheet punching machine, and putting the cut positive electrode wafers into a vacuum drying oven at the temperature of 60 ℃ for drying for 12 hours for later use;
step S702, mixing ethylene carbonate and diethyl carbonate according to a mass ratio of 1:1 under the condition of room temperature, and adding LiPF with a concentration of 1mol/L 6 Fully mixing and standing for 24 hours to obtain electrolyte;
step S703, punching the ceramic-coated polyethylene material into a circular sheet with the diameter of 16mm, transferring the circular sheet into a vacuum drying oven with the temperature of 55 ℃, and vacuum drying for 24 hours to obtain a diaphragm;
and step 704, in a glove box with the water and oxygen contents being less than 0.1ppm, using the lithium sheet as a counter electrode, and assembling the lithium sheet, the electrolyte obtained in the step 702, the positive electrode sheet obtained in the step 6 and the separator obtained in the step 703 into a secondary battery.
The application relates to a method for directly preparing a secondary battery by ultrasonic repairing of waste lithium iron phosphate, which repairs Li in the waste lithium iron phosphate by ultrasonic reaction + The vacancy defect and the Li/Fe inversion defect can be eliminated without short-time annealing and complicated metal element separation and purification processes, so that the consumption of chemical reagents and energy sources can be obviously reduced, the energy consumption is greatly reduced, the recovery process is simplified, and the economic benefit is improved to the greatest extent.
Example 5
Based on example 1, this example mainly describes a method for directly preparing a secondary battery from waste lithium iron phosphate, which specifically includes:
s1, preparing a positive electrode plate by using waste lithium iron phosphate particles;
and S2, using the lithium sheet as a counter electrode, and assembling the lithium sheet, the positive electrode sheet, the electrolyte and the diaphragm into the secondary battery.
Further, the specific method of step S1 includes:
step S601, weighing waste lithium iron phosphate particles, a conductive agent (conductive carbon black, SP) and a binder (polyvinylidene fluoride, PVDF) according to a mass ratio of 8:1:1, and adding the waste lithium iron phosphate particles, the conductive agent and the binder into a ball milling tank;
step S602, adding a proper amount of solvent (N-methyl pyrrolidone, NMP) to ensure the viscosity of the electrode slurry, and uniformly mixing various substances to form a slurry with fluidity;
and S603, uniformly scraping the electrode slurry on the surface of the aluminum foil by using a 120 mu m scraper, and then placing the aluminum foil into a 80 ℃ blast drying oven for drying for 8 hours, and obtaining the positive electrode plate after the aluminum foil is completely dried.
Further, the specific method of step S2 includes:
step S701, compacting the positive electrode plate by using a roller press, cutting the positive electrode plate into positive electrode wafers with the diameter of 14mm by using a sheet punching machine, and putting the cut positive electrode wafers into a vacuum drying oven at the temperature of 60 ℃ for drying for 12 hours for later use;
step S702, mixing ethylene carbonate and diethyl carbonate according to a mass ratio of 1:1 under the condition of room temperature, and adding LiPF with a concentration of 1mol/L 6 Fully mixing and standing for 24 hours to obtain electrolyte;
step S703, punching the ceramic-coated polyethylene material into a circular sheet with the diameter of 16mm, transferring the circular sheet into a vacuum drying oven with the temperature of 55 ℃, and vacuum drying for 24 hours to obtain a diaphragm;
and step 704, in a glove box with the water and oxygen contents being less than 0.1ppm, using the lithium sheet as a counter electrode, and assembling the lithium sheet, the electrolyte obtained in the step 702, the positive electrode sheet obtained in the step 6 and the separator obtained in the step 703 into a secondary battery.
The application relates to a method for directly preparing a secondary battery by ultrasonic repairing of waste lithium iron phosphate, which repairs Li in the waste lithium iron phosphate by ultrasonic reaction + The vacancy defect and the Li/Fe inversion defect can be eliminated without short-time annealing and complicated metal element separation and purification processes, so that the consumption of chemical reagents and energy sources can be obviously reduced, the energy consumption is greatly reduced, the recovery process is simplified, and the economic benefit is improved to the greatest extent.
Example 6
Based on examples 1-5, the present example mainly describes the test results of a method for directly preparing a secondary battery by ultrasonic repairing of waste lithium iron phosphate.
The secondary batteries of examples 1 to 4 were tested using an arbinibt 2000 test system, with a charge-discharge voltage range of 2.5 to 4.2V, and cycled for 100 cycles (25 ℃) at 1C correspondence, resulting in initial coulombic efficiency and cycle performance.
The secondary batteries of examples 1 to 4 were also subjected to high rate performance tests using an arbinibt 2000 test system, with a voltage range of 2.5 to 4.2V and a current density of 0.2C to 5C. The test results are shown in Table 1.
Table 1 test results of secondary battery test by arbinibt 2000 test system
It can be seen that the capacity retention rate of S-LFP (waste lithium iron phosphate) at 100 circles under 1C current is only 87%, while that of ultrasonically regenerated LiFePO 4 The capacity retention rate of 100 circles under the current of 1C is generally over 90 percent, and RLFP (repaired lithium iron phosphate) -1.0M/1.5mL still has 135.1 mAh.g after 100 circles under the current -1 The specific discharge capacity of the steel sheet is as high as 97%. It follows that LiFePO regenerated by means of high-power ultrasound 4 Has better cycle performance than the common liquid phase method, and the result is mainly attributed to the high activation energy provided by the local high temperature and high pressure energy generated by ultrasonic cavitation bubble collapse, and the Li in the solution is promoted by combining the action of the reducer + Embedding FePO 4 The lattice also reduces Li/Fe dislocation defects (2.52%). The reduction of dislocation defects can significantly enhance lithium ion mobility kinetics, thereby improving electrochemical performance.
The above description is only of the preferred embodiments of the present application and it is not intended to limit the scope of the present application, but various modifications and variations can be made by those skilled in the art. Variations, modifications, substitutions, integration and parameter changes may be made to these embodiments by conventional means or may be made to achieve the same functionality within the spirit and principles of the present application without departing from such principles and spirit of the application.
Claims (10)
1. The method for directly preparing the secondary battery by ultrasonic repairing of the waste lithium iron phosphate is characterized by comprising the following steps of:
s1, mixing a reducing agent, lithium salt and a solvent to prepare a repairing solution;
s2, adding waste lithium iron phosphate powder into the repairing solution, and stirring and mixing to obtain a mixed solution;
s3, placing the mixed solution which is uniformly mixed into ultrasonic equipment for two-section ultrasonic treatment;
s4, carrying out centrifugal water washing on the solution subjected to ultrasonic treatment;
s5, putting the centrifuged solution into a drying oven for drying to obtain repaired lithium iron phosphate particles;
s6, preparing a positive electrode plate by using the repaired lithium iron phosphate particles;
and S7, using the lithium sheet as a counter electrode, and assembling the lithium sheet, the positive electrode sheet, the electrolyte and the diaphragm into the secondary battery.
2. The method for directly preparing the secondary battery by ultrasonic repairing of waste lithium iron phosphate according to claim 1, wherein the reducing agent in the step S1 is hydrazine hydrate, the lithium salt is lithium chloride and the solvent is ethylene glycol.
3. The method for directly preparing a secondary battery by ultrasonic repair of waste lithium iron phosphate according to claim 2, wherein in the primary solution prepared from lithium chloride and ethylene glycol, li is as follows + The concentration is 0.5-2.0M.
4. The method for directly preparing the secondary battery by ultrasonic repairing of waste lithium iron phosphate according to claim 3, wherein the adding amount of hydrazine hydrate in the repairing solution is 0.5-2.0 mL.
5. The method for directly preparing the secondary battery by ultrasonic repair of waste lithium iron phosphate according to any one of claims 1, 2, 3 or 4, wherein in the step S2, the stirring and mixing method is stirring at 500rpm/min at room temperature for 10min.
6. The method for directly preparing the secondary battery by ultrasonic repair of waste lithium iron phosphate according to any one of claims 1, 2, 3 or 4, wherein the specific method of step S3 comprises the following steps:
step S301, transferring the mixed solution into a box body of an ultrasonic cell crusher, extending an amplitude transformer into the mixed solution below 1cm of the liquid level, and setting the ultrasonic power to be 500W;
step S302, placing a 50mL small beaker filled with mixed liquid in a 500mL large beaker filled with tap water, and setting the ultrasonic process as two sections and the ultrasonic time as 25 minutes; then left to stand for 10min, followed by an additional 25min of ultrasound.
7. The method for directly preparing the secondary battery by ultrasonic repair of waste lithium iron phosphate according to any one of claims 1, 2, 3 or 4, wherein the specific method of step S4 is as follows:
s401, separating lithium iron phosphate particles from the mixed solution after the second ultrasonic treatment in a centrifugal way;
and S402, repeatedly washing with deionized water and ethanol to remove residual lithium chloride and hydrazine hydrate on the surfaces of the lithium iron phosphate particles.
8. The method for directly preparing the secondary battery by ultrasonic repairing of the waste lithium iron phosphate according to claim 7, wherein the specific method in the step S5 is as follows: and (3) putting the lithium iron phosphate particles obtained in the step (S4) into a vacuum drying oven, and drying for 12 hours at the temperature of 60 ℃ to obtain the repaired dry lithium iron phosphate particles.
9. The method for directly preparing the secondary battery by ultrasonic repair of waste lithium iron phosphate according to any one of claims 1, 2, 3 or 4, wherein the specific method of step S6 comprises the following steps:
step S601, weighing lithium iron phosphate particles, a conductive agent and a binder according to the mass ratio of 8:1:1, and adding the lithium iron phosphate particles, the conductive agent and the binder into a ball milling tank;
step S602, adding a proper amount of N-methyl pyrrolidone, and uniformly mixing to form electrode slurry;
and S603, uniformly scraping the electrode slurry on the surface of the aluminum foil by using a 120 mu m scraper, and then placing the aluminum foil into a 80 ℃ blast drying oven for drying for 8 hours, and obtaining the positive electrode plate after the aluminum foil is completely dried.
10. The method for directly preparing the secondary battery by ultrasonic repair of waste lithium iron phosphate according to any one of claims 2, 3 or 4, wherein the specific method of step S7 comprises the following steps:
step S701, compacting the positive electrode plate by using a roller press, cutting the positive electrode plate into positive electrode wafers with the diameter of 14mm by using a sheet punching machine, and putting the cut positive electrode wafers into a vacuum drying oven at the temperature of 60 ℃ for drying for 12 hours for later use;
step S702, mixing ethylene carbonate and diethyl carbonate according to a mass ratio of 1:1 under the condition of room temperature, and adding LiPF with a concentration of 1mol/L 6 Fully mixing and standing for 24 hours to obtain electrolyte;
step S703, punching the ceramic-coated polyethylene material into a circular sheet with the diameter of 16mm, transferring the circular sheet into a vacuum drying oven with the temperature of 55 ℃, and vacuum drying for 24 hours to obtain a diaphragm;
step S704, using the lithium sheet as a counter electrode, and assembling the lithium sheet with the electrolyte obtained in step S702, the positive electrode sheet obtained in step S6, and the separator obtained in step S703 into a secondary battery.
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