CN114388923B - Repairing and regenerating method of waste lithium iron phosphate positive electrode material and lithium iron phosphate positive electrode material - Google Patents
Repairing and regenerating method of waste lithium iron phosphate positive electrode material and lithium iron phosphate positive electrode material Download PDFInfo
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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 89
- 239000002699 waste material Substances 0.000 title claims abstract description 55
- 239000007774 positive electrode material Substances 0.000 title claims abstract description 48
- 238000000034 method Methods 0.000 title claims abstract description 35
- 230000001172 regenerating effect Effects 0.000 title claims abstract description 26
- 239000000843 powder Substances 0.000 claims abstract description 37
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 20
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 20
- 238000000137 annealing Methods 0.000 claims abstract description 12
- 238000001035 drying Methods 0.000 claims abstract description 10
- 238000003756 stirring Methods 0.000 claims abstract description 10
- 238000005406 washing Methods 0.000 claims abstract description 10
- 239000012298 atmosphere Substances 0.000 claims abstract description 8
- 239000012266 salt solution Substances 0.000 claims abstract description 8
- 239000003960 organic solvent Substances 0.000 claims abstract description 7
- 239000007787 solid Substances 0.000 claims abstract description 7
- 238000006243 chemical reaction Methods 0.000 claims abstract description 5
- 239000000203 mixture Substances 0.000 claims abstract description 5
- 238000010438 heat treatment Methods 0.000 claims abstract description 3
- 238000002156 mixing Methods 0.000 claims abstract description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 20
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 claims description 18
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 12
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 12
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 12
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 8
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 8
- 239000007788 liquid Substances 0.000 claims description 8
- 239000002904 solvent Substances 0.000 claims description 8
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 6
- 229910052786 argon Inorganic materials 0.000 claims description 5
- HSZCZNFXUDYRKD-UHFFFAOYSA-M lithium iodide Chemical compound [Li+].[I-] HSZCZNFXUDYRKD-UHFFFAOYSA-M 0.000 claims description 5
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 claims description 4
- 239000012448 Lithium borohydride Substances 0.000 claims description 2
- HOXMMMZZCHGDQT-UHFFFAOYSA-N benzene;n-[bis(dimethylamino)phosphoryl]-n-methylmethanamine Chemical compound C1=CC=CC=C1.CN(C)P(=O)(N(C)C)N(C)C HOXMMMZZCHGDQT-UHFFFAOYSA-N 0.000 claims description 2
- GMKDNCQTOAHUQG-UHFFFAOYSA-L dilithium;dioxido-oxo-sulfanylidene-$l^{6}-sulfane Chemical compound [Li+].[Li+].[O-]S([O-])(=O)=S GMKDNCQTOAHUQG-UHFFFAOYSA-L 0.000 claims description 2
- BBLSYMNDKUHQAG-UHFFFAOYSA-L dilithium;sulfite Chemical compound [Li+].[Li+].[O-]S([O-])=O BBLSYMNDKUHQAG-UHFFFAOYSA-L 0.000 claims description 2
- GNOIPBMMFNIUFM-UHFFFAOYSA-N hexamethylphosphoric triamide Chemical compound CN(C)P(=O)(N(C)C)N(C)C GNOIPBMMFNIUFM-UHFFFAOYSA-N 0.000 claims description 2
- 239000012280 lithium aluminium hydride Substances 0.000 claims description 2
- -1 lithium aluminum hydride Chemical compound 0.000 claims description 2
- AFRJJFRNGGLMDW-UHFFFAOYSA-N lithium amide Chemical compound [Li+].[NH2-] AFRJJFRNGGLMDW-UHFFFAOYSA-N 0.000 claims description 2
- 229910001383 lithium hypophosphite Inorganic materials 0.000 claims description 2
- GLNWILHOFOBOFD-UHFFFAOYSA-N lithium sulfide Chemical compound [Li+].[Li+].[S-2] GLNWILHOFOBOFD-UHFFFAOYSA-N 0.000 claims description 2
- 229910052754 neon Inorganic materials 0.000 claims description 2
- GKAOGPIIYCISHV-UHFFFAOYSA-N neon atom Chemical compound [Ne] GKAOGPIIYCISHV-UHFFFAOYSA-N 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 2
- 238000011069 regeneration method Methods 0.000 abstract description 10
- 229910010707 LiFePO 4 Inorganic materials 0.000 abstract description 8
- 230000008929 regeneration Effects 0.000 abstract description 7
- 229910052751 metal Inorganic materials 0.000 abstract description 4
- 239000002184 metal Substances 0.000 abstract description 2
- 229910021645 metal ion Inorganic materials 0.000 abstract description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 14
- 229910052744 lithium Inorganic materials 0.000 description 14
- 239000010405 anode material Substances 0.000 description 13
- 239000000243 solution Substances 0.000 description 12
- 239000012535 impurity Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 5
- 239000012300 argon atmosphere Substances 0.000 description 5
- 238000005119 centrifugation Methods 0.000 description 5
- 239000003638 chemical reducing agent Substances 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 230000009469 supplementation Effects 0.000 description 5
- 239000000725 suspension Substances 0.000 description 5
- 229910001416 lithium ion Inorganic materials 0.000 description 4
- 230000014759 maintenance of location Effects 0.000 description 4
- 238000004064 recycling Methods 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 239000003153 chemical reaction reagent Substances 0.000 description 3
- 239000011267 electrode slurry Substances 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 229910018091 Li 2 S Inorganic materials 0.000 description 2
- 229910010082 LiAlH Inorganic materials 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 239000010406 cathode material Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 230000001502 supplementing effect Effects 0.000 description 2
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000000921 elemental analysis Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 238000009616 inductively coupled plasma Methods 0.000 description 1
- 239000003273 ketjen black Substances 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000012916 structural analysis Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 239000002341 toxic gas Substances 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/54—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
- 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
-
- 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
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/84—Recycling of batteries or fuel cells
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Secondary Cells (AREA)
- Primary Cells (AREA)
Abstract
The invention discloses a repairing and regenerating method of a waste lithium iron phosphate positive electrode material and the lithium iron phosphate positive electrode material, wherein the method comprises the following steps: 1) Preparing a reducing lithium salt solution by adopting an organic solvent; 2) Mixing waste lithium iron phosphate powder with a reducing lithium salt solution, and placing the mixture in a constant temperature device for heating, stirring and reacting, wherein the reaction atmosphere is inert; 3) Collecting the solid powder in the step 2), washing sequentially, and drying; 4) And annealing the solid powder obtained in the step 3) in an inert atmosphere to obtain the repairing regenerated lithium iron phosphate positive electrode material. In the method, lithium salt is a main consumable, the organic solvent can be recycled, the steps are simple, secondary pollution is avoided, and the cost is low. In the regeneration process, metal ions in the waste LiFePO 4 anode cannot be leached out, so that metal resources in the waste anode are utilized to the maximum extent. The regenerated lithium iron phosphate positive electrode material has higher crystallinity and shows excellent electrochemical performance.
Description
Technical Field
The invention belongs to the technical field of lithium ion battery materials, and particularly relates to a repairing and regenerating method of a waste lithium iron phosphate positive electrode material and the lithium iron phosphate positive electrode material.
Background
The large-scale use of lithium ion batteries gradually causes concern about insufficient resource supply, and the contradiction between resource supply and demand can be solved by effectively recycling retired lithium ion batteries. The current method for recycling the positive electrode of the waste lithium ion battery mainly comprises two steps: fire and wet methods. The purpose of both methods is to separate valuable metal elements from the spent anode alone, but this usually involves high energy consumption and the use of large amounts of chemical raw materials, and therefore higher recovery costs. On the other hand, the recovery processes of the two methods can generate toxic gas or have excessive discharge of pollutant liquid, so that secondary pollution is risk. For the waste lithium iron phosphate (LiFePO 4) cathode material, the element with higher value is only lithium, and the content of the lithium element is also less, so that the traditional method for recycling the lithium iron phosphate cathode material is inexpensiveness in economic benefit. The lithium iron phosphate anode material has lithium deficiency and FePO 4 impurity phase in the charge-discharge cycle process, so that the battery performance is poor, and if the defects can be directly repaired in a targeted manner, the use of excessive chemical reagents is avoided, and the method has important significance for recycling the retired lithium iron phosphate battery.
Two reagents are generally required for repairing the waste lithium iron phosphate positive electrode material: lithium salt and a reducing agent. The existing repairing method has the defect that the proportion of lithium salt to reducing agent is required to be strictly controlled, so that a method for simply and effectively regenerating the waste lithium iron phosphate positive electrode material is needed.
Disclosure of Invention
In view of the problems existing in the prior art, the application aims to provide a repairing and regenerating method of a waste lithium iron phosphate positive electrode material, which utilizes a reducing lithium salt to convert FePO 4 impurities in the waste lithium iron phosphate positive electrode material into LiFePO 4, wherein the reducing lithium salt serves as a lithium source and a reducing agent. The application fully utilizes valuable metal elements in the waste lithium iron phosphate anode material, avoids the use of an additional reducing agent, and has the advantages of less consumption of reducing lithium salt, economy, high efficiency and no pollution. After regeneration, the lithium source missing in the waste lithium iron phosphate anode material is supplemented, meanwhile, the FePO 4 impurity phase is repaired into LiFePO 4, and the discharge capacity of the waste lithium iron phosphate anode material can be recovered. In addition, the application obviously improves the crystallinity of the waste lithium iron phosphate anode material and the cycle performance thereof by implementing the regeneration step.
In order to achieve the above purpose, the application provides a repairing and regenerating method of a waste lithium iron phosphate positive electrode material, which comprises the following steps:
1) Preparing a reducing lithium salt solution by adopting an organic solvent;
2) Mixing waste lithium iron phosphate powder with a reducing lithium salt solution, and placing the mixture in a constant temperature device for heating, stirring and reacting, wherein the reaction atmosphere is inert;
3) Collecting the solid powder in the step 2), washing sequentially, and drying;
4) And annealing the solid powder obtained in the step 3) in an inert atmosphere to obtain the repairing regenerated lithium iron phosphate positive electrode material.
Preferably, in the step 1), the reducing lithium salt includes at least one of reducing lithium salts such as lithium iodide (LiI), lithium borohydride (LiBH 4), lithium aluminum hydride (LiAlH 4), lithium sulfite (Li 2SO3), lithium thiosulfate (Li 2S2O3), lithium sulfide (Li 2 S), lithium hypophosphite (LiH 2PO2), and lithium amide (LiNH 2).
Preferably, in step 1), the concentration of the reducing lithium salt solution is 0.03 to 0.3M, more preferably 0.05 to 0.1M.
Preferably, in step 1), the organic solvent is at least one of acetonitrile, diethyl ether, ethanol, tetrahydrofuran, dimethyl sulfoxide, dimethylformamide, dioxane, hexamethylphosphoramide benzene and carbon tetrachloride.
Preferably, the solid to liquid ratio in step 2) is from 10 to 300g/L, more preferably from 50 to 200g/L; the stirring speed is 100-2000 rpm, the reaction temperature is 25-100 ℃, and the reaction time is 2-50 h.
Preferably, the washing solvent in the step 3) is at least one of water, ethanol, acetonitrile, tetrahydrofuran, dimethyl sulfoxide, dimethylformamide, dioxane and hexamethylphosphoramide.
Preferably, the drying temperature in step 3) is from 60 to 120 ℃, more preferably from 80 to 100 ℃.
Preferably, the annealing temperature in step 4) is 500 to 900 ℃, more preferably 600 to 700 ℃; the annealing time is 1 to 18 hours, more preferably 5 to 10 hours.
Preferably, in step 2) and step 4), the inert atmosphere is at least one of argon, nitrogen and neon.
In addition, the application also provides a lithium iron phosphate positive electrode material, which is prepared by the repairing and regenerating method of the waste lithium iron phosphate positive electrode material.
The technical scheme provided by the application can achieve the following beneficial effects:
1) The waste lithium iron phosphate anode material treated by the repairing and regenerating method has higher crystallinity and better electrochemical performance compared with the waste lithium iron phosphate anode material. At the current density of 1C, the specific capacity of the regenerated lithium iron phosphate positive electrode material is increased to more than 151mAh/g, and the capacity retention rate of the regenerated lithium iron phosphate positive electrode material after 100 weeks of circulation is increased to more than 97%.
2) According to the method for directly supplementing lithium to the waste lithium iron phosphate anode material by the reducing lithium salt, the lithium salt is a main consumable, and the organic solvent can be recycled without additional reducing agent, so that the dosage of the reagent is reduced, no secondary pollution is caused, the recovery cost is reduced, the steps are simple, and the method is suitable for industrial popularization and application. In addition, in the regeneration process, metal ions in the waste LiFePO 4 anode are not lost, so that metal resources in the waste anode are utilized to the maximum extent.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is an XRD pattern of a spent lithium iron phosphate powder and a regenerated lithium iron phosphate positive electrode material of example 1.
Fig. 2 is a graph of the first discharge capacity of the spent lithium iron phosphate powder and the regenerated lithium iron phosphate positive electrode material of example 1.
FIG. 3 is a graph of the cycling performance at 1C of a spent lithium iron phosphate powder with the regenerated lithium iron phosphate positive electrode of example 1.
Detailed Description
The present application will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present application more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.
Example 1
A repairing and regenerating method of waste lithium iron phosphate positive electrode material comprises the following specific steps:
(1) Preparing 100ml of LiI solution with the concentration of 0.1M by taking acetonitrile as a solvent;
(2) Adding waste lithium iron phosphate powder into the solution in the step (1), wherein the solid-liquid ratio is 50g/L, the stirring speed is 400rpm, reacting for 12 hours at 60 ℃, and introducing argon as a shielding gas;
(3) Centrifuging the suspension obtained in the step (2) to obtain lithium iron phosphate positive electrode powder after lithium supplementation, washing 3 times with acetonitrile, collecting the positive electrode powder through centrifugation, and drying at 100 ℃ for 12 hours;
(4) And (3) annealing the lithium iron phosphate powder obtained in the step (3) in a tubular furnace in an argon atmosphere at 700 ℃ for 5 hours to obtain the repairing and regenerating lithium iron phosphate positive electrode material.
Example 2
A repairing and regenerating method of waste lithium iron phosphate positive electrode material comprises the following specific steps:
(1) Preparing 100ml of LiBH 4 solution with concentration of 0.05M by taking tetrahydrofuran as a solvent;
(2) Adding waste lithium iron phosphate powder into the solution in the step (1), wherein the solid-liquid ratio is 200g/L, the stirring speed is 600rpm, reacting for 6 hours at 40 ℃, and introducing nitrogen as a shielding gas;
(3) Centrifuging the suspension obtained in the step (2) to obtain lithium iron phosphate positive electrode powder after lithium supplementation, washing 3 times with tetrahydrofuran, collecting the positive electrode powder through centrifugation, and drying at 80 ℃ for 6 hours;
(4) And (3) annealing the lithium iron phosphate powder obtained in the step (3) in a tubular furnace in an argon atmosphere at 600 ℃ for 10 hours to obtain the repairing and regenerating lithium iron phosphate positive electrode material.
Example 3
A repairing and regenerating method of waste lithium iron phosphate positive electrode material comprises the following specific steps:
(1) Preparing 100ml of LiAlH 4 solution with concentration of 0.03M by using diethyl ether as a solvent;
(2) Adding waste lithium iron phosphate powder into the solution in the step (1), wherein the solid-liquid ratio is 100g/L, the stirring speed is 300rpm, reacting for 6 hours at 40 ℃, and introducing argon as a shielding gas;
(3) Centrifuging the suspension obtained in the step (2) to obtain lithium iron phosphate positive electrode powder after lithium supplementation, washing 3 times with diethyl ether, collecting the positive electrode powder through centrifugation, and drying at 60 ℃ for 12 hours;
(4) And (3) annealing the lithium iron phosphate powder obtained in the step (3) in a tube furnace in an argon atmosphere at 800 ℃ for 6 hours to obtain the repairing and regenerating lithium iron phosphate positive electrode material.
Example 4
A repairing and regenerating method of waste lithium iron phosphate positive electrode material comprises the following specific steps:
(1) Preparing 100ml of Li 2SO3 solution with concentration of 0.1M by taking ethanol as a solvent;
(2) Adding waste lithium iron phosphate powder into the solution in the step (1), wherein the solid-liquid ratio is 150g/L, the stirring speed is 500rpm, reacting for 10 hours at 60 ℃, and introducing nitrogen as a shielding gas;
(3) Centrifuging the suspension obtained in the step (2) to obtain lithium iron phosphate positive electrode powder after lithium supplementation, washing the lithium iron phosphate positive electrode powder with ethanol for 3 times, collecting the positive electrode powder through centrifugation, and drying the positive electrode powder at 70 ℃ for 10 hours;
(4) And (3) annealing the lithium iron phosphate powder obtained in the step (3) in a tubular furnace in an argon atmosphere at 600 ℃ for 8 hours to obtain the repairing and regenerating lithium iron phosphate positive electrode material.
Example 5
A repairing and regenerating method of waste lithium iron phosphate positive electrode material comprises the following specific steps:
(1) Preparing 100ml of Li 2 S solution with concentration of 0.08M by taking ethanol as a solvent;
(2) Adding waste lithium iron phosphate powder into the solution prepared in the step (1), wherein the solid-to-liquid ratio is 150g/L, the stirring speed is 1000rpm, reacting for 5 hours at 70 ℃, and introducing argon as a shielding gas;
(3) Centrifuging the suspension obtained in the step (2) to obtain lithium iron phosphate positive electrode powder after lithium supplementation, washing the lithium iron phosphate positive electrode powder with ethanol for 3 times, collecting the positive electrode powder through centrifugation, and drying the positive electrode powder at 70 ℃ for 10 hours;
(4) And (3) annealing the lithium iron phosphate powder obtained in the step (3) in a tubular furnace in an argon atmosphere at 700 ℃ for 5 hours to obtain the repairing and regenerating lithium iron phosphate positive electrode material.
And respectively carrying out performance test and analysis on the lithium iron phosphate anode material obtained in the embodiment.
Elemental analysis:
The Inductively Coupled Plasma (ICP) test shows that the element composition of the waste lithium iron phosphate positive electrode powder and the regenerated positive electrode material obtained in each embodiment is shown in the table I, and the regeneration method provided by the invention can effectively supplement lithium missing in the waste lithium iron phosphate positive electrode, and the molar ratio of lithium to phosphate radical in the regenerated positive electrode material after supplementing lithium salt is close to 1:1.
TABLE elemental composition of regenerated anode and waste lithium iron phosphate Material obtained in various examples of the invention
| Molar ratio of | Li/P | Fe/P | P/P |
| Waste lithium iron phosphate | 0.81 | 1.04 | 1 |
| Example 1 | 0.99 | 1.03 | 1 |
| Example 2 | 1.02 | 0.98 | 1 |
| Example 3 | 0.97 | 1.01 | 1 |
| Example 4 | 1.01 | 0.98 | 1 |
| Example 5 | 0.98 | 0.97 | 1 |
Structural analysis:
Referring to fig. 1, XRD comparison is performed on the waste lithium iron phosphate anode and the regenerated anode material collected in example 1 by using an X-ray diffractometer, it can be observed that after the lithium source is supplemented, the diffraction peak corresponding to the impurity FePO 4 completely disappears, and the regenerated anode material shows a single LiFePO 4 pure phase, and the crystallinity is higher, which indicates that the FePO 4 impurity is completely converted into LiFePO 4 phase.
Electrochemical performance analysis:
1. preparing a battery pole piece: waste or regenerated positive electrode material, ketjen black and polyvinylidene fluoride binder are mixed according to the following ratio of 8:1:1, adding N-methyl pyrrolidone solvent to prepare positive electrode slurry, coating the positive electrode slurry on aluminum foil, vacuum drying the positive electrode slurry at 100 ℃ for 24 hours to prepare a pole piece with a regular shape, and recording the quality of the pole piece.
2. Electrochemical performance test: and assembling the obtained pole piece, a lithium piece, an elastic piece, a gasket and a Celgard diaphragm in a glove box to obtain the button cell. The assembled battery was electrochemically tested using the marhan blue electric battery test system with a voltage window of 2.5-4.0V and charge and discharge tests at different rates (table two). Under the current density of 1C, the first discharge specific capacity of the button cell prepared from the waste lithium iron phosphate material is only 111.2mAh/g (figure 2), and the capacity retention rate of 100 circles of circulation is 90 percent (figure 3); the first discharge specific capacity of the button cell assembled by the regenerated lithium iron phosphate positive electrode material prepared in the embodiment 1 of the invention is improved to 151mAh/g (figure 2), and the capacity retention rate of 100 cycles is improved to 97% (figure 3), which shows that the regeneration method provided by the invention obviously improves the electrochemical performance of the waste lithium iron phosphate positive electrode.
Table II electrochemical properties of the regenerated anode and waste lithium iron phosphate Material obtained in the examples of the present invention
In conclusion, by implementing the above repair and regeneration steps on the waste lithium iron phosphate anode, no impurity exists in the repaired and regenerated anode material, and a single pure phase of LiFePO 4 is shown. Collecting the positive electrode materials in different regeneration stages, assembling the positive electrode materials into a button cell, and performing charge and discharge test under 1C current. Compared with the waste lithium iron phosphate positive electrode material before regeneration, the discharge specific capacity of the regenerated material is obviously improved, and the capacity retention rate is improved from 90% to 97% after the material is circulated for 100 weeks under the current of 1C. Therefore, the regeneration method provided by the invention can obviously improve the electrochemical performance of the waste lithium iron phosphate anode material, and is simple, effective, energy-saving and environment-friendly.
Variations and modifications of the above embodiments will occur to those skilled in the art to which the invention pertains from the foregoing disclosure and teachings. Therefore, the present invention is not limited to the above-described embodiments, but is intended to be capable of modification, substitution or variation in light thereof, which will be apparent to those skilled in the art in light of the present teachings. In addition, although specific terms are used in the present specification, these terms are for convenience of description only and do not limit the present invention in any way.
Claims (7)
1. The repairing and regenerating method for the waste lithium iron phosphate positive electrode material is characterized by comprising the following steps of:
1) Preparing a reducing lithium salt solution by adopting an organic solvent, wherein the organic solvent is at least one of acetonitrile, diethyl ether, ethanol, tetrahydrofuran, dimethyl sulfoxide, dimethylformamide, dioxane, hexamethylphosphoramide benzene and carbon tetrachloride, the reducing lithium salt comprises at least one of lithium iodide, lithium borohydride, lithium aluminum hydride, lithium sulfite, lithium thiosulfate, lithium sulfide, lithium hypophosphite and lithium amide, and the concentration of the reducing lithium salt solution is 0.03-0.3M;
2) Mixing waste lithium iron phosphate powder with a reducing lithium salt solution, and placing the mixture in a constant temperature device for heating, stirring and reacting, wherein the reaction atmosphere is inert;
3) Collecting the solid powder in the step 2), washing sequentially, and drying;
4) And annealing the solid powder obtained in the step 3) in an inert atmosphere to obtain the repairing regenerated lithium iron phosphate positive electrode material.
2. The method for repairing and regenerating the waste lithium iron phosphate positive electrode material according to claim 1, which is characterized in that: the solid-liquid ratio in the step 2) is 10-300 g/L, the stirring speed is 100-2000 rpm, the reaction temperature is 25-100 ℃, and the reaction time is 2-50 h.
3. The method for repairing and regenerating the waste lithium iron phosphate positive electrode material according to claim 1, which is characterized in that: the washing solvent in the step 3) is at least one of water, ethanol, acetonitrile, tetrahydrofuran, dimethyl sulfoxide, dimethylformamide, dioxane and hexamethylphosphoramide.
4. The method for repairing and regenerating the waste lithium iron phosphate positive electrode material according to claim 1, which is characterized in that: the drying temperature in the step 3) is 60-120 ℃.
5. The method for repairing and regenerating the waste lithium iron phosphate positive electrode material according to claim 1, which is characterized in that: the annealing temperature in the step 4) is 500-900 ℃ and the annealing time is 1-18 h.
6. The method for repairing and regenerating the waste lithium iron phosphate positive electrode material according to claim 1, which is characterized in that: in the step 2) and the step 4), the inert atmosphere is at least one of argon, nitrogen and neon.
7. A lithium iron phosphate positive electrode material is characterized in that: the method for repairing and regenerating a waste lithium iron phosphate positive electrode material according to any one of claims 1 to 6.
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