CN116435640A - Recycling method of lithium iron phosphate waste batteries - Google Patents
Recycling method of lithium iron phosphate waste batteries 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 76
- 238000000034 method Methods 0.000 title claims abstract description 60
- 239000010926 waste battery Substances 0.000 title claims abstract description 40
- 238000004064 recycling Methods 0.000 title claims abstract description 30
- 239000007774 positive electrode material Substances 0.000 claims abstract description 97
- 239000000203 mixture Substances 0.000 claims abstract description 83
- 238000010438 heat treatment Methods 0.000 claims abstract description 24
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 22
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 22
- 159000000000 sodium salts Chemical class 0.000 claims abstract description 22
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims abstract description 21
- 239000007772 electrode material Substances 0.000 claims abstract description 16
- 238000000926 separation method Methods 0.000 claims abstract description 11
- 238000007599 discharging Methods 0.000 claims abstract description 8
- 239000011230 binding agent Substances 0.000 claims abstract description 7
- 239000006258 conductive agent Substances 0.000 claims abstract description 6
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical group [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 44
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 22
- 239000000126 substance Substances 0.000 claims description 22
- 238000005470 impregnation Methods 0.000 claims description 19
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical class [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 17
- 239000007864 aqueous solution Substances 0.000 claims description 17
- 229910052744 lithium Inorganic materials 0.000 claims description 17
- 229910001415 sodium ion Inorganic materials 0.000 claims description 16
- 238000002156 mixing Methods 0.000 claims description 13
- KTQBSFHFHLRPFZ-UHFFFAOYSA-K lithium sodium iron(2+) phosphate Chemical compound [Na+].[Li+].P(=O)([O-])([O-])[O-].[Fe+2] KTQBSFHFHLRPFZ-UHFFFAOYSA-K 0.000 claims description 12
- 229910052698 phosphorus Inorganic materials 0.000 claims description 11
- 239000000243 solution Substances 0.000 claims description 9
- 238000012360 testing method Methods 0.000 claims description 9
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 claims description 8
- 238000005520 cutting process Methods 0.000 claims description 8
- UIIMBOGNXHQVGW-DEQYMQKBSA-M Sodium bicarbonate-14C Chemical compound [Na+].O[14C]([O-])=O UIIMBOGNXHQVGW-DEQYMQKBSA-M 0.000 claims description 7
- 239000005708 Sodium hypochlorite Substances 0.000 claims description 7
- 229910052782 aluminium Inorganic materials 0.000 claims description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 7
- 239000011780 sodium chloride Substances 0.000 claims description 7
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 claims description 7
- 238000004448 titration Methods 0.000 claims description 7
- 239000011888 foil Substances 0.000 claims description 6
- 238000005868 electrolysis reaction Methods 0.000 claims description 3
- 239000011259 mixed solution Substances 0.000 claims description 3
- 150000002823 nitrates Chemical class 0.000 claims description 3
- 239000003115 supporting electrolyte Substances 0.000 claims description 3
- 238000009210 therapy by ultrasound Methods 0.000 claims description 3
- 239000012266 salt solution Substances 0.000 claims description 2
- 238000002791 soaking Methods 0.000 claims description 2
- 229910052808 lithium carbonate Inorganic materials 0.000 abstract description 6
- 239000011248 coating agent Substances 0.000 abstract description 5
- 238000000576 coating method Methods 0.000 abstract description 5
- 230000000052 comparative effect Effects 0.000 description 25
- 238000011084 recovery Methods 0.000 description 18
- 239000002699 waste material Substances 0.000 description 16
- 230000008569 process Effects 0.000 description 13
- 238000002386 leaching Methods 0.000 description 12
- 239000000463 material Substances 0.000 description 12
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 10
- 239000002253 acid Substances 0.000 description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 9
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 9
- 239000000706 filtrate Substances 0.000 description 8
- 239000010405 anode material Substances 0.000 description 7
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 description 7
- 229910001416 lithium ion Inorganic materials 0.000 description 7
- 230000014759 maintenance of location Effects 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 7
- 238000011069 regeneration method Methods 0.000 description 7
- 239000005955 Ferric phosphate Substances 0.000 description 6
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 6
- 229940032958 ferric phosphate Drugs 0.000 description 6
- 229910000399 iron(III) phosphate Inorganic materials 0.000 description 6
- 229910052708 sodium Inorganic materials 0.000 description 6
- 239000011734 sodium Substances 0.000 description 6
- 239000002184 metal Substances 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000011161 development Methods 0.000 description 4
- 230000018109 developmental process Effects 0.000 description 4
- 238000005265 energy consumption Methods 0.000 description 4
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- 239000000843 powder Substances 0.000 description 4
- 230000001698 pyrogenic effect Effects 0.000 description 4
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 3
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 3
- 235000011114 ammonium hydroxide Nutrition 0.000 description 3
- 238000000498 ball milling Methods 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 238000004146 energy storage Methods 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- 238000011056 performance test Methods 0.000 description 3
- 239000011574 phosphorus Substances 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 230000008929 regeneration Effects 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- 239000002893 slag Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- 239000011149 active material Substances 0.000 description 2
- 238000001354 calcination Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910001386 lithium phosphate Inorganic materials 0.000 description 2
- 229910003002 lithium salt Inorganic materials 0.000 description 2
- 159000000002 lithium salts Chemical class 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- TWQULNDIKKJZPH-UHFFFAOYSA-K trilithium;phosphate Chemical compound [Li+].[Li+].[Li+].[O-]P([O-])([O-])=O TWQULNDIKKJZPH-UHFFFAOYSA-K 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 102000004310 Ion Channels Human genes 0.000 description 1
- NEAPKZHDYMQZCB-UHFFFAOYSA-N N-[2-[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]piperazin-1-yl]ethyl]-2-oxo-3H-1,3-benzoxazole-6-carboxamide Chemical compound C1CN(CCN1CCNC(=O)C2=CC3=C(C=C2)NC(=O)O3)C4=CN=C(N=C4)NC5CC6=CC=CC=C6C5 NEAPKZHDYMQZCB-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- QSNQXZYQEIKDPU-UHFFFAOYSA-N [Li].[Fe] Chemical compound [Li].[Fe] QSNQXZYQEIKDPU-UHFFFAOYSA-N 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
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- 238000004364 calculation method Methods 0.000 description 1
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- 239000010406 cathode material Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000007600 charging Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000010277 constant-current charging Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 230000009849 deactivation Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000012065 filter cake Substances 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 230000014509 gene expression Effects 0.000 description 1
- 238000009854 hydrometallurgy Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 235000014413 iron hydroxide Nutrition 0.000 description 1
- 229910000398 iron phosphate Inorganic materials 0.000 description 1
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000003760 magnetic stirring Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 239000002923 metal particle Substances 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- DPTATFGPDCLUTF-UHFFFAOYSA-N phosphanylidyneiron Chemical compound [Fe]#P DPTATFGPDCLUTF-UHFFFAOYSA-N 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 238000011165 process development Methods 0.000 description 1
- 108090000623 proteins and genes Proteins 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 229910000162 sodium phosphate Inorganic materials 0.000 description 1
- 239000001488 sodium phosphate Substances 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 229910052596 spinel Inorganic materials 0.000 description 1
- 239000011029 spinel Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000002277 temperature effect Effects 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 description 1
- 238000001132 ultrasonic dispersion Methods 0.000 description 1
Images
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
-
- 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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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention relates to a recycling method of a lithium iron phosphate waste battery, which mainly comprises five steps of discharging and disassembling the lithium iron phosphate waste battery, separating an electrode material from a current collector, obtaining the content of main elements in a positive electrode material mixture, impregnating the positive electrode material mixture, and performing heat treatment on the impregnated positive electrode material mixture. The separation process of the positive electrode material and the current collector adopts an electrolytic method, so that the primary separation is more convenient and environment-friendly; the specific concentration ranges of lithium carbonate and sodium salt are defined according to the content of each element in the lithium iron phosphate to be recovered, and the original binder and the conductive agent are used for carbon coating by limiting the heat treatment conditions, so that the uniformity of the regenerated positive electrode material and the stability of the electrochemical performance are ensured.
Description
Technical Field
The invention relates to the technical field of battery recycling, in particular to a recycling method of lithium iron phosphate waste batteries.
Background
The energy storage device with large capacity, long service life, high safety and low cost is a core unit for realizing the urgent need of renewable energy source application, smart grid construction and electric automobile development, and the lithium ion battery is used as an efficient energy storage device and is entering a rapid development stage. The lithium iron phosphate material has the advantages of abundant and easily available raw materials, little dependence on external resources, environmental friendliness and the like, and the stable lattice structure endows the lithium iron phosphate material with relatively safe and long-circulating genes, so that the lithium iron phosphate material is an important guarantee for benign development of new energy automobiles and renewable energy sources in the future. With the technical progress, the design of the battery pack system optimizes the innovation of integrated manufacturing technologies such as blades, CTP, JTM and the like, effectively makes up for the short energy density board of the lithium iron phosphate material, and the lithium iron phosphate battery in 2020 enters a rapid development stage, has larger and larger market scale, has larger market space in the aspects of energy storage, 5G base stations, new energy automobiles, renewable energy grid connection and the like, and is expected to take the dominant position of the market in the future for a long time.
However, after hundreds of charge and discharge cycles, the internal structure of the lithium iron phosphate battery will change irreversibly, which results in blocking of the lithium ion channel, thereby resulting in deactivation of the battery. The average service life of the current lithium iron phosphate battery is 3-8 years, and the commercial application of the lithium iron phosphate battery is earlier, so that the explosion period of the retirement of the lithium iron phosphate battery is started. It is estimated that by 2025, only about 100GWh of lithium iron phosphate waste batteries are produced in china, and the retired amount of lithium iron phosphate is larger in the long term, and the retired amount of the large amount makes recycling and reutilization of the lithium iron phosphate waste batteries and materials a serious challenge. The waste power battery electrolyte which is not treated is extremely easy to react in the environment, and causes pollution to soil, water sources and the like. The recovery of metal elements such as lithium resources in the waste lithium ion batteries can reduce the waste of the resources and better relieve the pressure of the lithium resources. At present, the object of lithium ion battery recovery in the global scope is mainly a ternary lithium ion battery containing noble metals such as cobalt. The economic value of lithium iron phosphate battery recovery is lower, and the enterprises for developing lithium iron phosphate waste recovery business are few, and most of the enterprises are in experimental research stage.
At present, the recovery treatment modes of the anode materials of the waste lithium iron phosphate batteries mainly comprise pyrogenic recovery, wet recovery, direct regeneration and the like, wherein the pyrogenic recovery is used for forcefully crushing the waste lithium iron phosphate batteries through an external acting force, the screened powder is calcined at a high temperature, and carbon, organic matters and related binders in the powder are burned off through a high temperature effect, so that valuable metals and metal oxides are finally obtained. And then, mechanical sorting is carried out, and different metals and oxides thereof are orderly recovered. The fire recovery has the advantages of early process development and mature technical route, so that the fire recovery has extremely wide application and high recovery rate. However, the technological content is not high in the process route, the simple pyrogenic calcination process is often insufficient in recovery, a large amount of pollution is accompanied, the energy consumption is huge, and the recovery value of the lithium iron phosphate material is low, so that the method is not suitable for large-scale application. The wet method for recovering valuable metal is to recover valuable metal elements in the waste lithium iron phosphate battery anode material by utilizing a hydrometallurgy mode. The waste lithium iron phosphate anode material is leached by a leaching agent, elements such as lithium, iron, phosphorus and the like enter a solution in an ionic form, and the leaching agent is separated and recovered after impurity removal and purification. Lithium is generally recovered in the form of lithium carbonate and lithium phosphate, while iron is generally recovered in the form of iron phosphate and iron hydroxide. The wet full-component leaching process can realize full-component recovery of the waste lithium iron phosphate anode material, and has the advantages of high metal recovery rate and high purity of recovered products; however, since the olivine-type lithium iron phosphate has a very stable structure, the structure is destroyed by adding strong acid, and the acid consumption is large, and a large amount of alkali is correspondingly added for neutralization in the subsequent steps, so that the recovery cost is high; in addition, the recovery process has the problems of large amount of waste liquid, long process flow, complex operation and the like. As disclosed in CN114349030a, a comprehensive wet recycling method of waste lithium iron phosphate positive plates is disclosed, wherein positive plates and the like disassembled from waste lithium iron battery cells are crushed and classified to obtain positive powder and aluminum scraps; acid leaching the positive electrode powder, and adding iron powder for reactionObtaining acid leaching filtrate and acid leaching slag, wherein the acid leaching slag is used for preparing crude carbon powder; adding an Al removing agent into the acid leaching filtrate, and filtering to obtain refined acid leaching filtrate and Al removing slag; after the iron-phosphorus ratio of the refined acid leaching filtrate is regulated, adding a mixed solution of hydrogen peroxide and ammonia water, and filtering and washing to obtain a crude ferric phosphate filter cake and a Li-containing filtrate; treating the crude ferric phosphate to obtain an anhydrous ferric phosphate finished product; adding ammonia water and (NH) into the filtrate containing Li 4 ) 2 CO 3 Filtering, washing with water to obtain residue and refined Li-containing filtrate, concentrating the refined Li-containing filtrate, adding ammonia water to adjust pH, and adding ((NH) 4 ) 2 CO 3 Filtering to obtain crude Li 2 CO 3 The method can realize the recycling of all elements of iron, phosphorus, lithium, aluminum foil and carbon. The direct regeneration method is to strip the active material from the positive plate, and then regenerate the active material in high-temperature protective gas with or without adding other reagents, namely recover the electrochemical performance of the failed lithium iron phosphate material by adding the missing material. The direct regeneration method has the advantages of short flow and simple operation. However, the currently used regeneration method cannot remove the influence of carbon on the positive electrode material, so that the carbon content of the regenerated lithium iron phosphate positive electrode material is higher, and the specific discharge capacity and the volumetric energy density are reduced. Meanwhile, the lithium iron phosphate positive electrode material obtained through direct regeneration is generally difficult to meet commercial demands, particularly the discharge specific capacity at high multiplying power is low, which is probably due to the fact that the crystal lattice of the waste positive electrode material is not completely destroyed, and the regeneration process is not favored. CN115472825a discloses a preparation process of a high-stability sodium ion battery positive electrode material, which uses lithium iron phosphate as a positive electrode, uses lithium salt as an electrolyte solution, uses a carbon material as a negative electrode, connects a power supply to perform constant current charging, and transfers lithium ions in the liquid phase solution out of the positive electrode, and obtains olivine-structured ferric phosphate after charging is finished; and then uniformly mixing the ferric phosphate and the organic sodium salt, ball milling, calcining at 200-400 ℃ in a protective atmosphere, and transferring sodium ions in the organic sodium salt into the ferric phosphate to obtain the ferric sodium phosphate anode material.
Thus, there are many improvements in the existing methods for recovering valuable metals from waste lithium iron phosphate batteries. In order to facilitate the later use, it is necessary to develop a simple and easy method capable of realizing the recycling of the lithium iron phosphate waste batteries.
Disclosure of Invention
The invention aims to provide a recycling method of lithium iron phosphate waste batteries, which aims to solve various problems in the recycling process of the anode materials of the existing lithium iron phosphate batteries.
The invention provides a recycling method of lithium iron phosphate waste batteries, which comprises the following steps:
step 1, discharging and disassembling a lithium iron phosphate waste battery:
completely discharging the lithium iron phosphate waste battery, then mechanically disassembling, removing the shell, separating out the positive plate, the negative plate and the diaphragm, and cutting the positive plate;
step 2, separation of electrode material and current collector:
separating the positive electrode material from a current collector to obtain a positive electrode material mixture and an aluminum foil, wherein the positive electrode material mixture comprises lithium iron phosphate, a conductive agent and a binder;
step 3, obtaining the content of main elements in the positive electrode material mixture:
taking a positive electrode material mixture with the mass of m, testing and detecting the content of elements Li, fe and P, and measuring the amounts of substances of the positive electrode material mixture to be a, b and d respectively;
step 4, positive electrode material mixture impregnation:
crushing a positive electrode material mixture with the mass of M at normal temperature and normal pressure, uniformly mixing the crushed positive electrode material mixture with lithium carbonate powder, titrating and impregnating the crushed positive electrode material mixture with a sodium salt aqueous solution, and obtaining an impregnated positive electrode material mixture by using the volume of the sodium salt mixed solution consumed after the titration is completed as V;
wherein the amount of the substance of the lithium carbonate powder is n, the concentration of the substance of sodium ions in the sodium salt is c, and the following conditions are satisfied:
step 5, heat treatment of the impregnated positive electrode material mixture:
and (3) obtaining the carbon-coated lithium iron sodium phosphate after the impregnated positive electrode material mixture obtained in the step (4).
As a preferable scheme of the invention, in the step 1, the complete discharge of the lithium iron phosphate waste battery is realized by soaking the lithium iron phosphate waste battery in saturated NaCl solution for 3-10 h.
As a preferred embodiment of the present invention, in the step 2, separation of the electrode material from the current collector is accomplished by an electrolytic method; specifically comprises preparing an electrolytic cell containing saturated nitrate as supporting electrolyte, cutting the electrode sheet into pieces of 0.1cm 2 ～400cm 2 Two positive pole pieces are arranged at two poles of an electrolytic cell, periodically-changed square wave current or triangular wave current is applied to the two poles, and the current density is 1mA/cm 2 ～500mA/cm 2 The method comprises the steps of carrying out a first treatment on the surface of the And after the electrode material is separated from the surface of the current collector after electrolysis, the current collector and the electrode material are taken out from the electrolytic tank, and the current collector and the electrode material are separated.
As a preferred embodiment of the present invention, in the step 3, the content of the main element in the obtained positive electrode material mixture is that a plurality of positive electrode material mixture samples in the same batch are randomly selected, the samples with the mass of m are respectively weighed and the content of the element Li, fe and P is respectively detected, and the weighted average calculation is performed on the content obtained by the randomly selected plurality of samples, so as to obtain the amounts of the substances of the element Li, fe and P as a, b and d, respectively.
As a preferred aspect of the present invention, in the step 4, the pulverization of the positive electrode material mixture is performed by means of ball milling, preferably, the ball milling is performed at a rotation speed of 200 to 400rpm for 3 to 8 hours; the mixing is achieved by stirring, preferably magnetic stirring.
As a preferred embodiment of the present invention, in the step 4, the volume V of the sodium salt aqueous solution upon complete impregnation is measured by the following method: the method is characterized in that the method comprises the steps of metering from a first drop of sodium salt aqueous solution, dropwise adding until a drop of sodium salt aqueous solution is added, then crushing and uniformly mixing with lithium carbonate powder, and obtaining a positive electrode material mixture into a paste, wherein the total sum of the sodium salt aqueous solution for dropwise adding is V.
As a preferred embodiment of the present invention, in the step 4, the sodium salt solution titrating impregnation is incomplete impregnation, complete impregnation or excessive impregnation.
As a preferred embodiment of the present invention, in the step 4, after the impregnated positive electrode material mixture is prepared, an ultrasonic treatment step is further included; further, the ultrasonic treatment condition is that the ultrasonic frequency is 20-50kHz, and the stirring rotating speed is 80-300 revolutions per minute. The contact surface of the mixture of sodium and the positive electrode material is larger by dipping the mixture by sodium salt aqueous solution, and the mixing uniformity of the mixture of sodium ions and the positive electrode material is further improved by ultrasonic dispersion, so that the uniformity of the finally regenerated positive electrode material is improved, and the regenerated positive electrode material has good electrochemical performance.
In a preferred embodiment of the present invention, in the step 4, the sodium salt is sodium carbonate, sodium bicarbonate, sodium hypochlorite or sodium chloride.
As a preferred embodiment of the present invention, in the step 4, the concentration c of the sodium ion substance in the sodium salt is further:
as a preferred embodiment of the present invention, the heat treatment in said step 5 is carried out at 650℃to 750℃for 1 to 4 hours under an atmosphere of N 2 Or Ar; further preferably, the heat treatment temperature may be selected to be 650 ℃,655 ℃,660 ℃,665 ℃,670 ℃,675 ℃,680 ℃,685 ℃,690 ℃,695 ℃,700 ℃,705 ℃,710 ℃,715 ℃,720 ℃,725 ℃,730 ℃,735 ℃,740 ℃,745 ℃,750 ℃; further preferably, the heat treatment time may be selected to be 1h,1.25h,1.5h,1.75h,2h,2.25h,2.5h,2.75h,3h.
Compared with the prior art, the beneficial effects of the technical scheme are as follows:
firstly, unlike the prior main stream lithium iron phosphate waste battery recovery by a pyrogenic process and a wet process, the invention does not need conventional strong mechanical separation or acid leaching and alkaline leaching, and adopts an electrolytic method with simple operation, low energy consumption and less pollution in the process of separating the positive electrode material from the current collector, so that the preliminary separation step is more convenient and environment-friendly.
Secondly, compared with the existing direct regeneration method, the method acquires the contents of lithium element, iron element and phosphorus element in the lithium iron phosphate anode material mixture to be recovered through sampling, determines the amount of added lithium through the contents of the three elements, creatively further introduces sodium to carry out doping modification on the lithium iron phosphate to be recovered, so that on one hand, the lithium element is rich, the heat treatment and the loss of lithium in the subsequent cycle process during use are convenient, and on the other hand, the initial capacity and the cycle performance of the battery are improved through the introduction of a proper amount of sodium.
Thirdly, the specific concentration range of lithium carbonate and sodium salt is limited according to the content of each element in the lithium iron phosphate to be recovered, and the fixed proportion of the lithium salt and the sodium salt in the mixed impregnating solution is maintained, so that the carbon-coated sodium-doped lithium iron phosphate with high initial capacity and good cycle performance is obtained; the fine definition of the specific introduction amount of lithium and sodium ensures the uniformity of the regenerated positive electrode material and the stability of electrochemical performance.
Fourth, the heat treatment process of the invention ensures the good performance of carbon coating, so that the regenerated positive electrode material has good conductivity, the performance of the positive electrode material is further promoted, and the conductive agent and the binder are fully utilized, thereby saving resources.
Fifth, the whole process of the invention fully considers the environmental protection and the operation simplicity in each link, has low energy consumption, and the prepared positive electrode material has good performance, and is suitable for being applied to middle-high-end lithium batteries.
Drawings
In order to more clearly illustrate the embodiments of the present invention, the drawings that are required for the detailed description of the present invention or the prior art will be briefly described, it being apparent that the drawings in the following description are some embodiments of the present invention and that other drawings may be obtained from these drawings without inventive effort for a person of ordinary skill in the art.
Fig. 1 is a flow chart of a recycling method of lithium iron phosphate waste batteries according to an embodiment of the invention.
Detailed Description
In order to make the technical problems solved, the technical solutions adopted and the technical effects achieved by the present invention more clear, the technical solutions of the embodiments of the present invention will be described in further detail below, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, based on the embodiments of the invention, which a person skilled in the art would obtain without making any inventive effort, are within the scope of the invention.
It should be noted that the terms "comprising" and "having" and any variations thereof in the embodiments herein are intended to cover a non-exclusive inclusion.
Examples 1 to 16
The embodiment 1-16 adopts the same batch of lithium iron phosphate waste batteries, and the recycling method comprises the following steps:
step 1, discharging and disassembling a lithium iron phosphate waste battery:
the method comprises the steps of completely discharging the lithium iron phosphate waste battery, specifically, completely discharging the lithium iron phosphate waste battery by immersing the lithium iron phosphate waste battery in saturated NaCl solution for 3-10 hours, then mechanically disassembling the lithium iron phosphate waste battery, removing a shell, separating a positive plate, a negative plate and a diaphragm, and cutting the positive plate;
step 2, separation of electrode material and current collector:
separating the positive electrode material from a current collector to obtain a positive electrode material mixture and an aluminum foil, wherein the positive electrode material mixture comprises lithium iron phosphate, a conductive agent and a binder;
specifically, the separation of the electrode material from the current collector is accomplished by an electrolytic method; comprises preparing an electrolytic cell containing saturated nitrate as a supporting electrolyte, cutting the electrode sheet into pieces of 0.1cm 2 ～400cm 2 Preferably cut into small pieces of 20X 5cm 2 Of course, the size of the small piece is not limited to this, and the cutting can be performed according to the situation of the point solution to the Caon; the two positive pole pieces are arranged at the two poles of an electrolytic cell, periodically-changed square wave current or triangular wave current is applied to the two poles, and the current density is 1mA/cm 2 ～500mA/cm 2 The method comprises the steps of carrying out a first treatment on the surface of the And after the electrode material is separated from the surface of the current collector by electrolysis, taking the current collector and the electrode material out of the electrolytic tank, and separating the mixture of the current collector and the positive electrode material.
In addition, similarly, the negative electrode sheet can be subjected to electrolytic separation by a similar method, and the copper foil is recovered for recycling.
The electrode material and the current collector are separated by the electrolytic method in the step 3, the reaction is milder, the extremely high temperature is not involved, a large amount of gas is not generated, and the like, and the method is simple and effective, environment-friendly and low in energy consumption.
Step 3, obtaining the content of main elements in the positive electrode material mixture:
randomly selecting 5 positive electrode material mixtures obtained after different batteries of the batch are subjected to the step 1-2, respectively obtaining positive electrode material mixtures with mass m=10g in urban areas, respectively testing and detecting the mass of substances of elements Li, fe and P, and obtaining the mass m=10g of positive electrode material mixtures of 5 samples through weighted average, wherein the mass of the substances of the elements Li, fe and P is equal to a=0.059mol, b=0.062 mol and d=0.064 mol;
example 1
Step 4, positive electrode material mixture impregnation:
crushing a positive electrode material mixture with the mass of M=500 g at normal temperature and normal pressure, uniformly mixing the positive electrode material mixture with lithium carbonate powder, titrating and impregnating the mixture with sodium carbonate aqueous solution, and obtaining an impregnated positive electrode material mixture, wherein the volume of the sodium carbonate aqueous solution consumed after the titration is V=0.34L; wherein sodium carbonate may also be replaced by sodium bicarbonate, sodium hypochlorite or sodium chloride.
Wherein the amount of the substance of the lithium carbonate powder is n=0.42 mol, and the concentration of the substance of sodium ion in sodium carbonate is c=1.05 mol/L;
step 5, heat treatment of the impregnated positive electrode material mixture:
and (3) obtaining the carbon-coated lithium iron sodium phosphate after the impregnated positive electrode material mixture obtained in the step (4), wherein the heat treatment is carried out under Ar atmosphere, and the temperature is kept at 690 ℃ for 2 hours.
Examples 2 to 4
Step 4-5 of example 2-4 is the same as step 4-5 of example 1 except that n corresponds to 0.44mol, 0.46mol and 0.48mol in this order.
Examples 5 to 7
Step 4-5 of example 5-7 is the same as step 4-5 of example 3 except that V corresponds to 0.3L, 0.32L and 0.36L in this order.
Example 8
Step 4, positive electrode material mixture impregnation:
crushing a positive electrode material mixture with the mass of M=500 g at normal temperature and normal pressure, uniformly mixing the positive electrode material mixture with lithium carbonate powder, titrating and impregnating the mixture with sodium carbonate aqueous solution, and obtaining an impregnated positive electrode material mixture, wherein the volume of the sodium carbonate aqueous solution consumed after the titration is V=0.45L; wherein sodium carbonate may also be replaced by sodium bicarbonate, sodium hypochlorite or sodium chloride.
Wherein the amount of the substance of the lithium carbonate powder is n=0.46 mol, and the concentration of the substance of sodium ion in sodium carbonate is c=0.7 mol/L;
step 5, heat treatment of the impregnated positive electrode material mixture:
and (3) obtaining the carbon-coated lithium iron sodium phosphate after the impregnated positive electrode material mixture obtained in the step (4), wherein the heat treatment is carried out under Ar atmosphere, and the temperature is kept at 690 ℃ for 2 hours.
Examples 9 to 11
Step 4-5 of examples 9-11 was the same as step 4-5 of example 8 except that V was 0.48L, 0.51L and 0.54L in this order.
Examples 12 to 16
Step 4-5 of examples 12-16 is compared to step 4-5 of example 10, except that the heating temperature and time correspond in sequence to: the temperature is kept at 650 ℃ for 3 hours, at 675 ℃ for 2.5 hours, at 700 ℃ for 2 hours, at 725 ℃ for 1.5 hours and at 750 ℃ for 1 hour, and the other materials are the same.
Comparative example 1
Step 4, positive electrode material mixture impregnation:
crushing a positive electrode material mixture with the mass of M=500 g at normal temperature and normal pressure, uniformly mixing the positive electrode material mixture with lithium carbonate powder, titrating and impregnating the mixture with sodium carbonate aqueous solution, and obtaining an impregnated positive electrode material mixture, wherein the volume of the sodium carbonate aqueous solution consumed after the titration is V=0.51L; wherein sodium carbonate may also be replaced by sodium bicarbonate, sodium hypochlorite or sodium chloride.
Wherein the amount of the substance of the lithium carbonate powder is n=0.38 mol, and the concentration of the substance of sodium ion in sodium carbonate is c=0.7 mol/L;
step 5, heat treatment of the impregnated positive electrode material mixture:
and (3) obtaining the carbon-coated lithium iron sodium phosphate after the impregnated positive electrode material mixture obtained in the step (4), wherein the heat treatment is carried out under Ar atmosphere, and the temperature is kept at 690 ℃ for 2 hours.
Comparative example 2
Step 4-5 of comparative example 2 was the same as step 4-5 of comparative example 1 except that n was 0.52 mol.
Comparative example 3
Step 4, positive electrode material mixture impregnation:
crushing a positive electrode material mixture with the mass of M=500 g at normal temperature and normal pressure, uniformly mixing the positive electrode material mixture with lithium carbonate powder, titrating and impregnating the mixture with sodium carbonate aqueous solution, and obtaining an impregnated positive electrode material mixture, wherein the volume of the sodium carbonate aqueous solution consumed after the titration is V=0.42L; wherein sodium carbonate may also be replaced by sodium bicarbonate, sodium hypochlorite or sodium chloride.
Wherein the amount of the substance of the lithium carbonate powder is n=0.46 mol, and the concentration of the substance of sodium ion in sodium carbonate is c=0.7 mol/L;
step 5, heat treatment of the impregnated positive electrode material mixture:
and (3) obtaining the carbon-coated lithium iron sodium phosphate after the impregnated positive electrode material mixture obtained in the step (4), wherein the heat treatment is carried out under Ar atmosphere, and the temperature is kept at 690 ℃ for 2 hours.
Comparative example 4
Step 4-5 of comparative example 4 was the same as step 4-5 of comparative example 3 except that V was 0.57L.
Comparative example 5
Step 4, positive electrode material mixture impregnation:
crushing a positive electrode material mixture with the mass of M=500 g at normal temperature and normal pressure, uniformly mixing the positive electrode material mixture with lithium carbonate powder, titrating and impregnating the mixture with sodium carbonate aqueous solution, and obtaining an impregnated positive electrode material mixture, wherein the volume of the sodium carbonate aqueous solution consumed after the titration is V=0.51L; wherein sodium carbonate may also be replaced by sodium bicarbonate, sodium hypochlorite or sodium chloride.
Wherein the amount of the substance of the lithium carbonate powder is n=0.46 mol, and the concentration of the substance of sodium ion in sodium carbonate is c=0.7 mol/L;
step 5, heat treatment of the impregnated positive electrode material mixture:
and (3) obtaining the carbon-coated lithium iron sodium phosphate after the impregnated positive electrode material mixture obtained in the step (4), wherein the heat treatment is carried out under Ar atmosphere, and the temperature is kept at 550 ℃ for 4 hours.
Comparative examples 6 to 8
Step 4-5 of comparative example 6-8 was compared with step 4-5 of comparative example 5 except that the heating temperature and time thereof were sequentially corresponded to: the temperature is kept at 600 ℃ for 3.5 hours, at 775 ℃ for 1 hour, at 800 ℃ for 0.75 hour, and the other materials are the same.
Testing
The electrochemical performance of the button cell was examined by using the carbon-coated lithium iron sodium phosphate of examples 1 to 16 and comparative examples 1 to 8 as the positive electrode active material, respectively. The button cell is prepared by mixing lithium iron phosphate active substances, conductive carbon black and PVDF according to the mass ratio of 90:7:3, mixing the materials in proportion to prepare slurry, coating the slurry on aluminum foil, baking the aluminum foil at 120 ℃ for 8 hours, and preparing the small round pole piece for manufacturing the button cell by rolling and cutting. The button cell was assembled in a glove box under conditions of water and oxygen content of 0.01ppm or less and electrolyte 1.0MLiPF6in EC:DMC:DEC =1:1:1 vol%. The conductivity of the battery was tested, and in addition, the battery cycle performance was tested under the following conditions: the charge-discharge voltage range was 2.5-4.2V (relative to li+/Li), the ambient temperature was 25 ℃, 0.2C charge-discharge was used, and the capacity retention rate was tested 100 times at 1C with cycling, resulting in battery performance, as shown in tables 1-2.
Table 1: examples 1 to 16 electrochemical performance test results
| 0.2C discharge capacity | Capacity retention rate | 0.2C discharge capacity | Capacity retention rate | ||
| Example 1 | 151.9mAh/g | 97.3％ | Example 9 | 154.1mAh/g | 98.5％ |
| Example 2 | 153mAh/g | 97.7％ | Example 10 | 155.6mAh/g | 98.8％ |
| Example 3 | 153.2mAh/g | 98.1％ | Example 11 | 154.2mAh/g | 98.1％ |
| Example 4 | 152.9mAh/g | 97.9％ | Example 12 | 153.8mAh/g | 98％ |
| Example 5 | 152.6mAh/g | 98.7％ | Example 13 | 154.9mAh/g | 98.3％ |
| Example 6 | 152.8mAh/g | 97.6％ | Example 14 | 155.5mAh/g | 98.6％ |
| Example 7 | 152.1mAh/g | 97.9％ | Example 15 | 155.1mAh/g | 98.3％ |
| Example 8 | 153.9mAh/g | 98.2％ | Example 16 | 155.3mAh/g | 98.2％ |
Table 2: comparative examples 1 to 8 electrochemical Performance test results
| 0.2C discharge capacity | Capacity retention rate | 0.2C discharge capacity | Capacity retention rate | ||
| Comparative example 1 | 136.3mAh/g | 95.3％ | Comparative example 5 | 116.3mAh/g | 88.3％ |
| Comparative example 2 | 135.4mAh/g | 95.2％ | Comparative example 6 | 125.4mAh/g | 90.2％ |
| Comparative example 3 | 138.4mAh/g | 95％ | Comparative example 7 | 121.1mAh/g | 89.8％ |
| Comparative example 4 | 137.3mAh/g | 91.2％ | Comparative example 8 | 117.5mAh/g | 87.6％ |
As can be readily seen from the test results shown in Table 1, when the relationships of n, c, and V satisfy
In three relations, the carbon-coated sodium lithium iron phosphate prepared by direct circulation from the waste lithium iron phosphate batteries shows better initial capacity and excellent circulation performance, wherein the 0.2C discharge capacity is 151mAh/g, and the capacity retention rate is more than 97%, because n, C and V are closely related to the content of Li, fe and P elements in the positive electrode material mixture in the disassembled and separated waste batteries; meanwhile, the conductive agent and the binder are directly used for carbon coating of the sodium iron lithium phosphate under the inert atmosphere, so that the conductivity of the recovered carbon-coated sodium iron lithium phosphate is improved, and the capacity and the cycle performance are promoted.
And comparing the test results shown in tables 1 and 2, it is not difficult to find that when the relationships of n, c and V do not satisfy the three relationships, the initial capacity slip is severe although the cycle performance of the carbon-coated lithium iron phosphate directly prepared from the lithium iron phosphate waste battery in a circulating way.
Specifically, the test results shown in table 1 indicate that in examples 1 to 4, as the amount n of the lithium-supplementing substance increases gradually from 0.42mol to 0.48mol, the 0.2C discharge capacity of the coin cell tends to increase first and then decrease, and peaks at n=0.46 mol, and the capacity retention rate is also highest here, which is mainly two reasons, namely, as the amount of lithium carbonate excessively introduced increases, the recovered and regenerated carbon-coated lithium iron sodium phosphate grains are refined, sintering fusion between grains is relieved, the discharge performance is increased, and thus both the initial capacity and the cycle performance are improved, but as lithium carbonate increases further, the excessive increase causes the formation of inactive lithium phosphate impurity phases, and thus the capacity and cycle performance of example 4 are slightly reduced. It can be seen from a combination of example 10 of table 1 and comparative examples 1-2 of table 2 that both insufficient and excessive amounts of lithium carbonate resulted in a decrease in initial capacity and cycle performance.
The test results shown in table 1 indicate that the amount of sodium ions introduced gradually increases in the order of examples 5, 6, 3, and 7, and also, the amount of sodium ions introduced gradually increases in examples 8 to 11, and comparison shows that when cv=0.357 mol, the capacity and cycle performance of the coin cell peaks, while the results of comparative examples 3 to 4 in combination with table 2 show similar results in that too much or too little sodium ions are detrimental to the improvement of the performance of the recycled positive electrode material, but sodium ions are similar to lithium ions as alkali metal particles, but because of the large difference in size and the mechanism thereof, it is presumed that excessive sodium occupies the position of Fe during sintering, resulting in unstable frame portions in the spinel structure or collapse such that the capacity and cycle performance are lowered. Further, examples 5, 6, 3, 7 are compared one by one with examples 8 to 11, and it can be seen that the values of cV of 5 and 8,6 and 9,3 and 10,7 and 11 are the same, but because c is different, and thus V is different for impregnation, the smaller c is, the larger V is, the more sufficient impregnation is for the positive electrode material mixture, and the more uniform and more sufficient reaction of lithium element and sodium element with the host material after sintering is promoted, thereby improving capacity and cycle performance.
The test results shown in Table 1 demonstrate that examples 10, 12-16 provide different heat treatment temperatures and corresponding times, and the results indicate that the heat retention time can be increased at low temperatures and decreased at high temperatures, and substantially better electrical properties can be achieved. However, in combination with comparative examples 5 to 8 of Table 2, the electrochemical performance is greatly reduced beyond the temperature range of 650 to 750 ℃ even if the holding time is adjusted, mainly because the temperature is too low to meet the reaction requirement, while the phase-change reaction is complicated due to the too high temperature, and the carbon coating effect is also greatly impaired, so that the heat treatment temperature should be limited to 650 to 750 ℃ and the holding time should be 1 to 3 hours, and the impregnated cathode material mixture should be heat-treated in an inert atmosphere.
Examples 17 to 20
Examples 17-20 used lithium iron phosphate waste batteries of different batches than examples 1-16, respectively. The preparation procedure and test method were similar to examples 1-16, with the parameters and electrochemical properties shown in Table 3.
Table 3: examples 17 to 20 electrochemical Performance test results
According to Table 3, examples 17 to 20 are respectively different from the other four different batches of lithium iron phosphate waste batteries of examples 1 to 16, and the materials, the process parameters and the like selected in the preparation process of the method are adopted, so that the content of Li, fe and P elements in the positive electrode material mixture is limited in three relational expressions, and the regenerated positive electrode material with excellent electrochemical performance is also obtained. The method is suitable for recycling the positive electrode materials of various types of lithium iron phosphate waste batteries, and the prepared regenerated positive electrode material is suitable for middle-high-end application scenes.
The above describes in detail a method for recycling lithium iron phosphate waste batteries disclosed in the examples of the present application, and the above describes in further detail the present invention in connection with specific preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, the architecture of the invention can be flexible and changeable without departing from the concept of the invention, and serial products can be derived. But a few simple derivatives or substitutions should be construed as falling within the scope of the invention as defined by the appended claims.
Claims (8)
1. The recycling method of the lithium iron phosphate waste battery is characterized by comprising the following steps of:
step 1, discharging and disassembling a lithium iron phosphate waste battery:
completely discharging the lithium iron phosphate waste battery, then mechanically disassembling, removing the shell, separating out the positive plate, the negative plate and the diaphragm, and cutting the positive plate;
step 2, separation of electrode material and current collector:
separating the positive electrode material from a current collector to obtain a positive electrode material mixture and an aluminum foil, wherein the positive electrode material mixture comprises lithium iron phosphate, a conductive agent and a binder;
step 3, obtaining the content of main elements in the positive electrode material mixture:
taking a positive electrode material mixture with the mass of m, testing and detecting the content of elements Li, fe and P, and measuring the amounts of substances of the positive electrode material mixture to be a, b and d respectively;
step 4, positive electrode material mixture impregnation:
crushing a positive electrode material mixture with the mass of M at normal temperature and normal pressure, uniformly mixing the crushed positive electrode material mixture with lithium carbonate powder, titrating and impregnating the crushed positive electrode material mixture with a sodium salt aqueous solution, and obtaining an impregnated positive electrode material mixture by using the volume of the sodium salt mixed solution consumed after the titration is completed as V;
wherein the amount of the substance of the lithium carbonate powder is n, the concentration of the substance of sodium ions in the sodium salt is c, and the following conditions are satisfied:
step 5, heat treatment of the impregnated positive electrode material mixture:
and (3) obtaining the carbon-coated lithium iron sodium phosphate after the impregnated positive electrode material mixture obtained in the step (4).
2. The recycling method of lithium iron phosphate waste batteries according to claim 1, wherein the recycling method is characterized by comprising the following steps: in the step 1, the lithium iron phosphate waste battery is completely discharged by soaking the lithium iron phosphate waste battery in saturated NaCl solution for 3-10 hours.
3. The recycling method of lithium iron phosphate waste batteries according to claim 1, wherein the recycling method is characterized by comprising the following steps: in the step 2, the separation of the electrode material and the current collector is completed by an electrolytic method; specifically comprises preparing an electrolytic cell containing saturated nitrate as supporting electrolyte, cutting the electrode sheet into pieces of 0.1cm 2 ～400cm 2 Is formed by arranging two positive pole piecesApplying periodically-changing square wave current or triangular wave current to two poles of the electrolytic cell, wherein the current density is 1mA/cm 2 ～500mA/cm 2 The method comprises the steps of carrying out a first treatment on the surface of the And after the electrode material is separated from the surface of the current collector after electrolysis, the current collector and the electrode material are taken out from the electrolytic tank, and the current collector and the electrode material are separated.
4. The recycling method of lithium iron phosphate waste batteries according to claim 1, wherein the recycling method is characterized by comprising the following steps: in said step 4, the sodium salt solution titrating impregnation is incomplete impregnation, complete impregnation or excessive impregnation.
5. The recycling method of lithium iron phosphate waste batteries according to claim 1, wherein the recycling method is characterized by comprising the following steps: in the step 4, after the positive electrode material mixture is prepared after impregnation, an ultrasonic treatment step is further included.
6. The recycling method of lithium iron phosphate waste batteries according to claim 5, wherein the recycling method is characterized in that: in the step 4, the sodium salt is sodium carbonate, sodium bicarbonate, sodium hypochlorite or sodium chloride.
7. The recycling method of lithium iron phosphate waste batteries according to any one of claims 1 to 6, characterized in that: in the step 4, the mass concentration c of the sodium ion substance in the sodium salt also satisfies:
8. the recycling method of lithium iron phosphate waste batteries according to any one of claims 1 to 6, characterized in that: the heat treatment in the step 5 is carried out at 650-750 ℃ for 1-3h under the atmosphere of N 2 Or Ar.
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