CN117800311A - Method for preparing sodium vanadium phosphate from lithium iron phosphate waste powder - Google Patents
Method for preparing sodium vanadium phosphate from lithium iron phosphate waste powder Download PDFInfo
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- iron phosphate
- lithium iron
- sodium vanadium
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- 239000000843 powder Substances 0.000 title claims abstract description 48
- ZMVMBTZRIMAUPN-UHFFFAOYSA-H [Na+].[V+5].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O Chemical compound [Na+].[V+5].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O ZMVMBTZRIMAUPN-UHFFFAOYSA-H 0.000 title claims abstract description 38
- 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 35
- 239000002699 waste material Substances 0.000 title claims abstract description 35
- 238000000034 method Methods 0.000 title claims abstract description 31
- 238000005245 sintering Methods 0.000 claims abstract description 45
- 239000000463 material Substances 0.000 claims abstract description 30
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 17
- 238000000227 grinding Methods 0.000 claims abstract description 12
- 238000001694 spray drying Methods 0.000 claims abstract description 12
- 239000002253 acid Substances 0.000 claims abstract description 10
- 238000002386 leaching Methods 0.000 claims abstract description 10
- 230000003647 oxidation Effects 0.000 claims abstract description 4
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 4
- 230000009467 reduction Effects 0.000 claims abstract description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 39
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 39
- 239000000706 filtrate Substances 0.000 claims description 30
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 29
- 239000002002 slurry Substances 0.000 claims description 24
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 claims description 21
- 239000002893 slag Substances 0.000 claims description 21
- 229910000398 iron phosphate Inorganic materials 0.000 claims description 19
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 18
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 18
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 18
- 239000007788 liquid Substances 0.000 claims description 18
- 238000000926 separation method Methods 0.000 claims description 18
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 claims description 17
- 238000001816 cooling Methods 0.000 claims description 17
- 239000008103 glucose Substances 0.000 claims description 17
- 239000002243 precursor Substances 0.000 claims description 15
- 239000011268 mixed slurry Substances 0.000 claims description 12
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 11
- UNTBPXHCXVWYOI-UHFFFAOYSA-O azanium;oxido(dioxo)vanadium Chemical compound [NH4+].[O-][V](=O)=O UNTBPXHCXVWYOI-UHFFFAOYSA-O 0.000 claims description 11
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 claims description 11
- 229910052742 iron Inorganic materials 0.000 claims description 11
- 229910052744 lithium Inorganic materials 0.000 claims description 11
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 9
- 238000004537 pulping Methods 0.000 claims description 9
- ZNCPFRVNHGOPAG-UHFFFAOYSA-L sodium oxalate Chemical compound [Na+].[Na+].[O-]C(=O)C([O-])=O ZNCPFRVNHGOPAG-UHFFFAOYSA-L 0.000 claims description 9
- 229940039790 sodium oxalate Drugs 0.000 claims description 9
- 239000007787 solid Substances 0.000 claims description 9
- 238000006243 chemical reaction Methods 0.000 claims description 8
- 238000007599 discharging Methods 0.000 claims description 7
- 229940062993 ferrous oxalate Drugs 0.000 claims description 7
- OWZIYWAUNZMLRT-UHFFFAOYSA-L iron(2+);oxalate Chemical compound [Fe+2].[O-]C(=O)C([O-])=O OWZIYWAUNZMLRT-UHFFFAOYSA-L 0.000 claims description 7
- 239000000126 substance Substances 0.000 claims description 7
- 229910010707 LiFePO 4 Inorganic materials 0.000 claims description 6
- 239000012298 atmosphere Substances 0.000 claims description 6
- 239000012065 filter cake Substances 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 6
- 239000011261 inert gas Substances 0.000 claims description 6
- 238000012216 screening Methods 0.000 claims description 6
- 239000007921 spray Substances 0.000 claims description 6
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims description 5
- 229910001448 ferrous ion Inorganic materials 0.000 claims description 5
- 239000005955 Ferric phosphate Substances 0.000 claims description 2
- 229940032958 ferric phosphate Drugs 0.000 claims description 2
- 229910000399 iron(III) phosphate Inorganic materials 0.000 claims description 2
- 229910001415 sodium ion Inorganic materials 0.000 abstract description 11
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 abstract description 10
- 238000002360 preparation method Methods 0.000 abstract description 9
- 230000008569 process Effects 0.000 abstract description 6
- 239000011734 sodium Substances 0.000 abstract 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 abstract description 5
- 239000002994 raw material Substances 0.000 abstract description 5
- 229910052708 sodium Inorganic materials 0.000 abstract description 5
- 239000012535 impurity Substances 0.000 abstract description 4
- 238000009776 industrial production Methods 0.000 abstract description 4
- 229910052698 phosphorus Inorganic materials 0.000 abstract description 4
- 229910052720 vanadium Inorganic materials 0.000 abstract description 4
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 abstract description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 abstract description 3
- 239000011574 phosphorus Substances 0.000 abstract description 3
- 238000004064 recycling Methods 0.000 abstract description 3
- 239000003795 chemical substances by application Substances 0.000 abstract description 2
- 238000001556 precipitation Methods 0.000 abstract description 2
- FPUYSDUWYZEIMA-UHFFFAOYSA-L sodium;iron(2+);oxalate Chemical compound [Na+].[Fe+2].[O-]C(=O)C([O-])=O FPUYSDUWYZEIMA-UHFFFAOYSA-L 0.000 abstract description 2
- 230000001502 supplementing effect Effects 0.000 abstract description 2
- 238000002156 mixing Methods 0.000 description 12
- 238000003756 stirring Methods 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 11
- 230000015572 biosynthetic process Effects 0.000 description 7
- 239000002270 dispersing agent Substances 0.000 description 7
- 239000002245 particle Substances 0.000 description 7
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 6
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 5
- 238000003786 synthesis reaction Methods 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 229910001416 lithium ion Inorganic materials 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000012299 nitrogen atmosphere Substances 0.000 description 3
- 238000003980 solgel method Methods 0.000 description 3
- 239000002228 NASICON Substances 0.000 description 2
- 239000010405 anode material Substances 0.000 description 2
- 238000004146 energy storage Methods 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000010532 solid phase synthesis reaction Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000010416 ion conductor Substances 0.000 description 1
- -1 iron ion Chemical class 0.000 description 1
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 1
- 229910052808 lithium carbonate Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 229920000447 polyanionic polymer Polymers 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
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- 238000011084 recovery Methods 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
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- 238000011160 research Methods 0.000 description 1
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Landscapes
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention discloses a method for preparing sodium vanadium phosphate by adopting lithium iron phosphate waste powder, which comprises the following steps: oxidation acid leaching, reduction acid leaching, sodium oxalate iron precipitation, vanadium doping and carbon doping, grinding, spray drying, presintering and sintering. The phosphorus source adopted by the preparation method is from battery waste, the sodium source is taken as a impurity removing agent, and the vanadium sodium phosphate can be synthesized only by supplementing the vanadium source, so that the preparation method has the advantages of low raw material cost, simple process flow, easy industrial production and realization of recycling of waste resources. The specific capacity of the sodium ion battery prepared from the carbon-coated sodium vanadium phosphate material prepared by the invention can reach more than 110mAh/g under the multiplying power of 0.1C (10 h charging), and the first charge-discharge efficiency is more than 97.5%.
Description
Technical Field
The invention belongs to the technical field of waste lithium battery material recovery treatment and regeneration, and particularly relates to a method for preparing sodium vanadium phosphate by adopting lithium iron phosphate waste powder.
Background
The lithium ion battery has the advantages of high energy density, good cycle performance and the like, and is widely applied to various energy storage devices. However, the global reserves of lithium resources are limited, and the lithium resources are not distributed uniformly, so that the large-scale application of the lithium ion battery is limited by the high cost. The sodium element and the lithium element belong to the IA main group, have similar physicochemical properties and storage mechanisms, and the sodium resource reserves are rich, widely distributed and low in price, so that the sodium ion battery is expected to replace the lithium ion battery in large-scale energy storage application.
The sodium ion battery electrode material is a key for influencing the performance of the sodium ion battery, and searching for a proper sodium ion battery anode material is a research focus for realizing practical application of the sodium ion battery. Polyanion compounds with sodium super ion conductor (NASICON) structure have a skeleton structure with openness, can rapidly conduct sodium ions, and have a very stable structure in the process of sodium ion deintercalation and are attracting attention. Sodium vanadium phosphate (Na) 3 V 2 (PO 4 ) 3 ) Has a typical NASICON structure, na + The ionic conductivity is good, the volume change is small in the embedding/extracting process, the voltage platform is moderate (3.4V), the theoretical specific energy is high (400 Wh/kg), the thermal stability is good, and the material is a sodium-ion battery anode material with good prospect.
At present, the preparation method of the sodium vanadium phosphate is mainly a solid phase method and a sol-gel method. The solid phase method is a traditional pulverizing process, has low cost, simple equipment and process, easy control of preparation conditions, high yield and convenient industrialized production, and is a common method. However, the calcination time is long, the obtained product has larger crystal size and wide particle size distribution range, and the method does not have the capacity of charging and discharging with large current, so that more and more reports on the synthesis of sodium vanadium phosphate by a sol-gel method are provided in recent years. The sol-gel method has the advantages of simple equipment, good chemical uniformity of the obtained precursor, easy occurrence of chemical reaction, low synthesis temperature, easy control of reaction process, longer synthesis period and larger difficulty of industrial production.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a method for preparing sodium vanadium phosphate by adopting lithium iron phosphate waste powder, which is suitable for industrial production, and simultaneously realizes recycling of waste lithium ion battery materials.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the invention provides a method for preparing sodium vanadium phosphate by adopting lithium iron phosphate waste powder, which comprises the following steps:
s1, pulping waste lithium iron phosphate battery powder by adding pure water, adding sulfuric acid and hydrogen peroxide for oxidation acid leaching, and carrying out solid-liquid separation to obtain iron phosphate slag and lithium-containing solution;
s2, adding pure water into the iron phosphate slag to slurry, adding phosphoric acid and iron powder to perform reduction acid leaching, and performing solid-liquid separation to obtain filtrate I and carbon slag;
s3, adding sodium oxalate into the filtrate I, and carrying out solid-liquid separation after full reaction to obtain a ferrous oxalate filter cake and a filtrate II;
s4, adding ammonium metavanadate and glucose into the filtrate II, and adjusting the solid content of the filtrate II after the ammonium metavanadate and glucose are fully dissolved to obtain mixed slurry;
s5, adding citric acid into the mixed slurry, grinding, and controlling the slurry D50 to be 2-5 mu m;
s6, conveying the ground slurry into a spray tower for spray drying to obtain precursor powder;
s7, placing the precursor powder into a sintering furnace under an inert gas atmosphere for presintering;
s8, continuously heating the presintered material, sintering at a high temperature in an inert gas atmosphere, cooling and discharging after sintering, and screening to remove iron to obtain the carbon-coated sodium vanadium phosphate material.
Preferably, in the step S1, the mass ratio of the lithium iron phosphate battery powder to the pure water is 1:3-6; the molar ratio of the lithium iron phosphate to the sulfuric acid and the hydrogen peroxide is n (LiFePO 4 ):n(H 2 SO 4 ):n(H 2 O 2 )＝1:0.55～0.7:0.6～0.8。
Preferably, in the step S2, the mass ratio of the iron phosphate slag to the pure water is 1:3-5; by a means ofThe molar ratio of the ferric phosphate to the phosphoric acid and the iron powder is n (FePO 4 ):n(H 3 PO 4 ):n(Fe)＝1:2～2.5:0.5～0.7。
Preferably, in the step S3, the addition amount of the sodium oxalate is 1.05 to 1.2 times the amount of the ferrous ion substance in the filtrate ii.
Preferably, in step S4, ammonium metavanadate and glucose are added to control n (PO 4 3- ):n(NH 4 VO 3 ) N (glucose) =18:12:1.5-2.5.
Preferably, in step S4, the solid content is 30 to 40%.
Preferably, in step S5, the amount of citric acid added is 0.3 to 0.5% of the mass of the slurry.
Preferably, in step S6, the air inlet temperature of the spray drying is 220±2 ℃, and the air outlet temperature is 80±5 ℃.
Preferably, in step S7, the pre-sintering temperature is 300 to 400 ℃.
Preferably, in step S8, the high-temperature sintering temperature is 700 to 850 ℃.
Compared with the prior art, the invention has the beneficial effects that:
(1) The phosphorus source adopted by the preparation method is from battery waste, the sodium source is taken as a impurity removing agent, and the vanadium sodium phosphate can be synthesized only by supplementing the vanadium source, so that the preparation method has the advantages of low raw material cost, simple process flow, easy industrial production and realization of recycling of waste resources.
(2) According to the preparation method disclosed by the invention, the main element P, fe, li, C in the lithium iron phosphate waste powder can be recycled, phosphorus is used for preparing sodium vanadium phosphate, iron is prepared into ferrous oxalate, lithium can be used for preparing battery-grade lithium carbonate in a lithium extraction working section, and carbon can be prepared into crude graphite powder.
(3) According to the preparation method, citric acid is used as a dispersing agent in grinding, so that materials are dispersed more uniformly, and the formation of impurity phases can be reduced in synthesis.
(4) According to the preparation method, the precursor is prepared by spray drying, the particle size of the material is finer, the particle size is uniform, the batch stability and tap density of the material can be improved, the obtained carbon-coated sodium vanadium phosphate material has higher energy density, the specific capacity of the material can reach more than 110mAh/g under the multiplying power of 0.1C (10 h charging), and the primary charge-discharge efficiency is more than 97.5%.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
The present invention is described in further detail below in conjunction with specific embodiments to make the present invention more clearly understood by those skilled in the art. The examples are given solely for the purpose of illustration and are not intended to limit the scope of the invention. In the examples of the present invention, all raw material components are commercially available products well known to those skilled in the art unless specified otherwise; unless specifically indicated, all technical means used are conventional means well known to those skilled in the art.
The invention provides a method for preparing sodium vanadium phosphate by adopting lithium iron phosphate waste powder, which is shown in a figure 1, and comprises the following steps:
step one, oxidizing acid leaching: and (3) pulping the waste lithium iron phosphate battery powder by adding pure water, adding sulfuric acid and hydrogen peroxide for oxidation acid leaching, and carrying out solid-liquid separation to obtain iron phosphate slag and lithium-containing solution.
The reaction principle of the step is as follows:
H 2 SO 4 +2LiFePO 4 (C)+H 2 O 2 ＝2FePO 4 +Li 2 SO 4 +2H 2 O+C
in a preferred embodiment, the mass ratio of the lithium iron phosphate battery powder to the pure water is 1:3-6.
In a preferred embodiment, the molar ratio of lithium iron phosphate to sulfuric acid and hydrogen peroxide is n (LiFePO 4 ):n(H 2 SO 4 ):n(H 2 O 2 )＝1:0.55～0.7:0.6～0.8。
Step two, reducing acid leaching: and (3) adding pure water into the iron phosphate slag to slurry, adding phosphoric acid and iron powder to perform reduction acid leaching, and performing solid-liquid separation to obtain filtrate I and carbon slag.
The reaction principle of the step is as follows:
2FePO 4 +4H 3 PO 4 +Fe＝3Fe(H 2 PO 4 ) 2
in a preferred embodiment, the mass ratio of the iron phosphate slag to the pure water is 1:3-5.
In a preferred embodiment, the number of iron powder is 100 to 200 mesh, and the molar ratio of iron phosphate to phosphoric acid to iron powder is n (FePO 4 ):n(H 3 PO 4 ):n(Fe)＝1:2～2.5:0.5～0.7。
Step three, sodium oxalate iron precipitation: adding sodium oxalate into the filtrate I, and carrying out solid-liquid separation after full reaction to obtain a ferrous oxalate filter cake and filtrate II.
The reaction principle of the step is as follows:
Fe(H 2 PO 4 ) 2 +NaCO 4 ＝2NaH 2 PO 4 +FeC 2 O 4 ↓
in a preferred embodiment, the sodium oxalate is added in an amount of 1.05 to 1.2 times the amount of the iron ion species in the filtrate II.
Step four, vanadium doping and carbon doping: adding ammonium metavanadate and glucose into the filtrate II, fully dissolving, and adding pure water to adjust the solid content of the filtrate II to obtain mixed slurry.
In a preferred embodiment, ammonium metavanadate and glucose are added to control n (PO 4 3- ):n(NH 4 VO 3 ) N (glucose) =18:12:1.5-2.5.
In a preferred embodiment, the solids content is adjusted to 30-40%.
Step five, grinding: and adding citric acid into the mixed slurry, grinding, and controlling the slurry D50 to be 2-5 mu m.
The citric acid is used as a dispersing agent, so that materials can be dispersed more uniformly, and the formation of impurity phases can be reduced during synthesis. In a preferred embodiment, the amount of citric acid added is 0.3 to 0.5% of the mass of the slurry.
Step six, spray drying: and conveying the ground slurry to a spray tower for spray drying to obtain precursor powder.
In a preferred embodiment, the air inlet temperature of spray drying is controlled to be 220+/-2 ℃, the air outlet temperature is controlled to be 80+/-5 ℃, the moisture content of the obtained precursor powder is less than or equal to 0.5%, and the particle size D50 is 10-15 mu m.
Step seven, presintering: pre-sintering the precursor powder in a sintering furnace under inert gas atmosphere to remove NH in the material 3 、H 2 O and other readily expanding gases.
In a preferred embodiment, the presintering temperature is 300-400 ℃ and the presintering is 3-5 hours.
Step eight, sintering: and continuously heating the presintered material, sintering at high temperature in an inert gas atmosphere, cooling and discharging after sintering, and screening to remove iron to obtain the carbon-coated sodium vanadium phosphate material.
In a preferred embodiment, the oxygen content in the sintering furnace is controlled to be less than or equal to 1ppm, the sintering temperature in the sintering constant temperature area is 700-850 ℃, the sintering time is 6-10 h, the material is cooled and discharged after the sintering is finished, the cooling section adopts a jacket to cool in a water cooling way, and the surface temperature of the discharged material is controlled to be less than or equal to 80 ℃.
Example 1
The method for preparing the sodium vanadium phosphate by adopting the lithium iron phosphate waste powder in the embodiment comprises the following steps:
mixing waste lithium iron phosphate battery powder and pure water according to a mass ratio of 1:5 for pulping, fully and uniformly stirring, and then mixing according to a molar ratio n (LiFePO 4 ):n(H 2 SO 4 ):n(H 2 O 2 ) Adding sulfuric acid and hydrogen peroxide in the ratio of (1:0.6:0.7), continuously stirring for 2 hours, and then carrying out solid-liquid separation to obtain iron phosphate slag and lithium-containing solution; mixing iron phosphate slag and pure water according to a mass ratio of 1:4 for pulping, and mixing the iron phosphate slag and the pure water according to a molar ratio of n (FePO 4 ):n(H 3 PO 4 ) Adding phosphoric acid and 150-mesh iron powder into n (Fe) =1:2.2:0.55, reacting for 4 hours, and performing solid-liquid separation to obtain filtrate I and carbon residue; adding sodium oxalate with the quantity which is 1.1 times of that of ferrous ion substances into the filtrate I, reacting for 1.5 hours, and then carrying out solid-liquid separation to obtain a ferrous oxalate filter cake and filtrate II; adding ammonium metavanadate and glucose into filtrate II, and controlling n (PO 4 3- ):n(NH 4 VO 3 ) N (glucose) =18:12:2, fully stirring and reacting for 4 hours, adding pure water to adjust the solid content of the slurry to 33%, fully stirring for 60 minutes,obtaining mixed slurry; adding citric acid accounting for 0.4% of the mass of the slurry into the mixed slurry, and grinding until the D50 of the slurry is 2-5 mu m; conveying the ground slurry into a spray tower for spray drying, controlling the air inlet temperature to be 220+/-2 ℃, and controlling the air outlet temperature to be 80+/-5 ℃ to obtain precursor powder with the moisture less than or equal to 0.5% and the particle size D50 of 10-15 mu m; pre-sintering the precursor powder in a sintering furnace under the nitrogen atmosphere at 350 ℃ for 5 hours, and then continuously heating up to perform high-temperature sintering; controlling the oxygen content in the sintering furnace to be less than or equal to 1ppm, controlling the sintering temperature in a sintering constant temperature zone to be 750 ℃, controlling the sintering time to be 10 hours, cooling and discharging after sintering, cooling a cooling section by adopting a jacket for water cooling, and controlling the surface temperature of a discharged material to be less than or equal to 80 ℃; and screening the sintered powder to remove iron, wherein the magnetic strength of the iron remover is more than or equal to 12000gs, and the magnetic foreign matters in the working procedure are less than or equal to 0.2ppm, so as to obtain the carbon-coated sodium vanadium phosphate material.
Example 2
The method for preparing the sodium vanadium phosphate by adopting the lithium iron phosphate waste powder in the embodiment comprises the following steps:
mixing waste lithium iron phosphate battery powder and pure water according to a mass ratio of 1:6 for pulping, fully and uniformly stirring, and then mixing according to a molar ratio n (LiFePO 4 ):n(H 2 SO 4 ):n(H 2 O 2 ) Adding sulfuric acid and hydrogen peroxide in the ratio of (1:0.7:0.8), continuously stirring for 2 hours, and then carrying out solid-liquid separation to obtain iron phosphate slag and lithium-containing solution; mixing iron phosphate slag and pure water according to a mass ratio of 1:3 for pulping, and mixing the iron phosphate slag and the pure water according to a molar ratio n (FePO 4 ):n(H 3 PO 4 ) Adding phosphoric acid and 200-mesh iron powder into n (Fe) =1:2.5:0.7, reacting for 4 hours, and then carrying out solid-liquid separation to obtain filtrate I and carbon residue; adding sodium oxalate with the quantity of 1.2 times of that of ferrous ion substances into the filtrate I, reacting for 1.5 hours, and then carrying out solid-liquid separation to obtain a ferrous oxalate filter cake and filtrate II; adding ammonium metavanadate and glucose into filtrate II, and controlling n (PO 4 3- ):n(NH 4 VO 3 ) N (glucose) =18:12:2.5, adding pure water to adjust the solid content of the slurry to 40% after fully stirring and reacting for 4 hours, and fully stirring for 60 minutes to obtain mixed slurry; adding citric acid accounting for 0.5% of the mass of the slurry into the mixed slurry, and grinding until the D50 of the slurry is 2-5 mu m; conveying the ground slurry into a spray tower for spray drying, and controlling air inletThe temperature is 220+/-2 ℃, the air outlet temperature is 80+/-5 ℃, and the moisture is less than or equal to 0.5%, so that precursor powder with the particle size D50 of 10-15 mu m is obtained; pre-sintering the precursor powder in a sintering furnace under nitrogen atmosphere at 400 ℃ for 5 hours, and then continuously heating up to perform high-temperature sintering; controlling the oxygen content in the sintering furnace to be less than or equal to 1ppm, controlling the sintering temperature in a sintering constant temperature zone to be 850 ℃, controlling the sintering time to be 8 hours, cooling and discharging after sintering, cooling a cooling section by adopting a jacket for water cooling, and controlling the surface temperature of a discharged material to be less than or equal to 80 ℃; and screening the sintered powder to remove iron, wherein the magnetic strength of the iron remover is more than or equal to 12000gs, and the magnetic foreign matters in the working procedure are less than or equal to 0.2ppm, so as to obtain the carbon-coated sodium vanadium phosphate material.
Example 3
The method for preparing the sodium vanadium phosphate by adopting the lithium iron phosphate waste powder in the embodiment comprises the following steps:
mixing waste lithium iron phosphate battery powder and pure water according to a mass ratio of 1:3 for pulping, fully and uniformly stirring, and then mixing according to a molar ratio n (LiFePO 4 ):n(H 2 SO 4 ):n(H 2 O 2 ) Adding sulfuric acid and hydrogen peroxide in the ratio of (1:0.55:0.6), continuously stirring for 2 hours, and then carrying out solid-liquid separation to obtain iron phosphate slag and lithium-containing solution; mixing iron phosphate slag and pure water according to a mass ratio of 1:5 for pulping, and mixing the iron phosphate slag and the pure water according to a molar ratio of n (FePO 4 ):n(H 3 PO 4 ) Adding phosphoric acid and 100-mesh iron powder into n (Fe) =1:2:0.5, reacting for 4 hours, and performing solid-liquid separation to obtain filtrate I and carbon residue; adding sodium oxalate with the quantity of 1.05 times of that of ferrous ion substances into the filtrate I, reacting for 1.5 hours, and then carrying out solid-liquid separation to obtain a ferrous oxalate filter cake and filtrate II; adding ammonium metavanadate and glucose into filtrate II, and controlling n (PO 4 3- ):n(NH 4 VO 3 ) N (glucose) =18:12:1.5, adding pure water to adjust the solid content of the slurry to 30% after fully stirring and reacting for 4 hours, and fully stirring for 60 minutes to obtain mixed slurry; adding citric acid accounting for 0.3% of the mass of the slurry into the mixed slurry, and grinding until the D50 of the slurry is 2-5 mu m; conveying the ground slurry into a spray tower for spray drying, controlling the air inlet temperature to be 220+/-2 ℃, and controlling the air outlet temperature to be 80+/-5 ℃ to obtain precursor powder with the moisture less than or equal to 0.5% and the particle size D50 of 10-15 mu m; pre-sintering the precursor powder in a sintering furnace under nitrogen atmosphere at 300 ℃ for 5 hours, and thenContinuously heating up to perform high-temperature sintering; controlling the oxygen content in the sintering furnace to be less than or equal to 1ppm, controlling the sintering temperature in a sintering constant temperature zone to be 700 ℃, controlling the sintering time to be 10 hours, cooling and discharging after sintering, cooling a cooling section by adopting a jacket for water cooling, and controlling the surface temperature of a discharged material to be less than or equal to 80 ℃; and screening the sintered powder to remove iron, wherein the magnetic strength of the iron remover is more than or equal to 12000gs, and the magnetic foreign matters in the working procedure are less than or equal to 0.2ppm, so as to obtain the carbon-coated sodium vanadium phosphate material.
Comparative example 1
The comparative example uses lithium iron phosphate waste powder to prepare sodium vanadium phosphate, and the raw materials and steps are basically the same as those of example 1, except that no citric acid dispersant is added in the grinding step.
Comparative example 2
The comparative example uses lithium iron phosphate waste powder to prepare sodium vanadium phosphate, and the raw materials and steps are basically the same as those of example 1, except that an ethylene glycol dispersing agent is added in the grinding step.
The carbon-coated sodium vanadium phosphate materials prepared in the above examples and comparative examples were used as a positive electrode material to prepare sodium ion batteries, and the electrochemical properties thereof were tested.
The physical and chemical properties of the carbon-coated sodium vanadium phosphate materials prepared in the above examples and comparative examples and the electrochemical performance test results of the corresponding sodium ion batteries are shown in table 1.
TABLE 1
As can be seen from comparative example 1 and comparative example 1, since comparative example 1 does not add a dispersing agent during grinding, resulting in poor uniformity of material dispersion, the prepared material has poor specific capacity and cycle efficiency; as can be seen from comparative examples 1 and 2, although comparative example 2 added the ethylene glycol dispersant, the prepared material had improved specific capacity and cycle efficiency, but was still less effective than the citric acid dispersant used in the present application.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.
Claims (10)
1. The method for preparing the sodium vanadium phosphate by adopting the lithium iron phosphate waste powder is characterized by comprising the following steps of:
s1, pulping waste lithium iron phosphate battery powder by adding pure water, adding sulfuric acid and hydrogen peroxide for oxidation acid leaching, and carrying out solid-liquid separation to obtain iron phosphate slag and lithium-containing solution;
s2, adding pure water into the iron phosphate slag to slurry, adding phosphoric acid and iron powder to perform reduction acid leaching, and performing solid-liquid separation to obtain filtrate I and carbon slag;
s3, adding sodium oxalate into the filtrate I, and carrying out solid-liquid separation after full reaction to obtain a ferrous oxalate filter cake and a filtrate II;
s4, adding ammonium metavanadate and glucose into the filtrate II, and adjusting the solid content of the filtrate II after the ammonium metavanadate and glucose are fully dissolved to obtain mixed slurry;
s5, adding citric acid into the mixed slurry, grinding, and controlling the slurry D50 to be 2-5 mu m;
s6, conveying the ground slurry into a spray tower for spray drying to obtain precursor powder;
s7, placing the precursor powder into a sintering furnace under an inert gas atmosphere for presintering;
s8, continuously heating the presintered material, sintering at a high temperature in an inert gas atmosphere, cooling and discharging after sintering, and screening to remove iron to obtain the carbon-coated sodium vanadium phosphate material.
2. The method for preparing sodium vanadium phosphate by adopting lithium iron phosphate waste powder according to claim 1, wherein in the step S1, the mass ratio of the lithium iron phosphate battery powder to the pure water is 1:3-6; the molar ratio of the lithium iron phosphate to the sulfuric acid and the hydrogen peroxide is n (LiFePO 4 ):n(H 2 SO 4 ):n(H 2 O 2 )＝1:0.55～0.7:0.6～0.8。
3. The method for preparing sodium vanadium phosphate by adopting lithium iron phosphate waste powder according to claim 1, wherein in the step S2, the mass ratio of the iron phosphate slag to the pure water is 1:3-5; the molar ratio of the ferric phosphate to the phosphoric acid and the iron powder is n (FePO 4 ):n(H 3 PO 4 ):n(Fe)＝1:2～2.5:0.5～0.7。
4. The method for preparing sodium vanadium phosphate by using lithium iron phosphate waste powder according to claim 1, wherein in the step S3, the adding amount of sodium oxalate is 1.05-1.2 times of the amount of ferrous ion substances in the filtrate ii.
5. The method for preparing sodium vanadium phosphate from lithium iron phosphate waste powder according to claim 1, wherein in step S4, ammonium metavanadate and glucose are added, and n (PO 4 3- ):n(NH 4 VO 3 ) N (glucose) =18:12:1.5-2.5.
6. The method for preparing sodium vanadium phosphate from lithium iron phosphate waste powder according to claim 1, wherein in step S4, the solid content is 30-40%.
7. The method for preparing sodium vanadium phosphate by using lithium iron phosphate waste powder according to claim 1, wherein in the step S5, the adding amount of the citric acid is 0.3-0.5% of the mass of the slurry.
8. The method for preparing sodium vanadium phosphate from lithium iron phosphate waste powder according to claim 1, wherein in step S6, the spray drying inlet air temperature is 220±2 ℃, and the outlet air temperature is 80±5 ℃.
9. The method for preparing sodium vanadium phosphate from lithium iron phosphate waste powder according to claim 1, wherein in step S7, the pre-sintering temperature is 300-400 ℃.
10. The method for preparing sodium vanadium phosphate from lithium iron phosphate waste powder according to claim 1, wherein in step S8, the high-temperature sintering temperature is 700-850 ℃.
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