CN117842956A - High-performance stable ferric phosphate and preparation method thereof - Google Patents
High-performance stable ferric phosphate and preparation method thereof Download PDFInfo
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- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 title claims abstract description 98
- 229910000399 iron(III) phosphate Inorganic materials 0.000 title claims abstract description 49
- 239000005955 Ferric phosphate Substances 0.000 title claims abstract description 48
- 229940032958 ferric phosphate Drugs 0.000 title claims abstract description 48
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 76
- 229910000398 iron phosphate Inorganic materials 0.000 claims abstract description 48
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims abstract description 42
- 239000002253 acid Substances 0.000 claims abstract description 40
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 38
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims abstract description 30
- 229910017604 nitric acid Inorganic materials 0.000 claims abstract description 30
- 238000003756 stirring Methods 0.000 claims abstract description 29
- 238000005406 washing Methods 0.000 claims abstract description 28
- 238000000034 method Methods 0.000 claims abstract description 27
- 238000006243 chemical reaction Methods 0.000 claims abstract description 21
- 238000001354 calcination Methods 0.000 claims abstract description 18
- 230000032683 aging Effects 0.000 claims abstract description 16
- 239000000843 powder Substances 0.000 claims abstract description 15
- 238000007873 sieving Methods 0.000 claims abstract description 14
- 239000007787 solid Substances 0.000 claims abstract description 14
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims abstract description 13
- 235000011114 ammonium hydroxide Nutrition 0.000 claims abstract description 13
- 239000002245 particle Substances 0.000 claims abstract description 8
- 238000000227 grinding Methods 0.000 claims abstract description 7
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 claims description 24
- 238000000498 ball milling Methods 0.000 claims description 14
- 238000000967 suction filtration Methods 0.000 claims description 12
- 230000035484 reaction time Effects 0.000 claims description 3
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 abstract description 17
- 239000012535 impurity Substances 0.000 abstract description 6
- 238000001914 filtration Methods 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 30
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 17
- 230000000052 comparative effect Effects 0.000 description 13
- 239000011259 mixed solution Substances 0.000 description 10
- 229910052742 iron Inorganic materials 0.000 description 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 150000001450 anions Chemical class 0.000 description 4
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000007774 positive electrode material Substances 0.000 description 3
- 230000002194 synthesizing effect Effects 0.000 description 3
- 239000003643 water by type Substances 0.000 description 3
- 238000005303 weighing Methods 0.000 description 3
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- 239000010405 anode material Substances 0.000 description 2
- 239000008187 granular material Substances 0.000 description 2
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 2
- BMTOKWDUYJKSCN-UHFFFAOYSA-K iron(3+);phosphate;dihydrate Chemical compound O.O.[Fe+3].[O-]P([O-])([O-])=O BMTOKWDUYJKSCN-UHFFFAOYSA-K 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000001000 micrograph Methods 0.000 description 2
- DPTATFGPDCLUTF-UHFFFAOYSA-N phosphanylidyneiron Chemical compound [Fe]#P DPTATFGPDCLUTF-UHFFFAOYSA-N 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 239000011574 phosphorus Substances 0.000 description 2
- NIFIFKQPDTWWGU-UHFFFAOYSA-N pyrite Chemical compound [Fe+2].[S-][S-] NIFIFKQPDTWWGU-UHFFFAOYSA-N 0.000 description 2
- 239000011028 pyrite Substances 0.000 description 2
- 229910052683 pyrite Inorganic materials 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 238000001027 hydrothermal synthesis Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 229910000358 iron sulfate Inorganic materials 0.000 description 1
- KRLFILPFAPWWFE-UHFFFAOYSA-K iron(3+) phosphoric acid phosphate Chemical compound P(O)(O)(O)=O.P(=O)([O-])([O-])[O-].[Fe+3] KRLFILPFAPWWFE-UHFFFAOYSA-K 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 229910001416 lithium ion Inorganic materials 0.000 description 1
- CASZBAVUIZZLOB-UHFFFAOYSA-N lithium iron(2+) oxygen(2-) Chemical compound [O-2].[Fe+2].[Li+] CASZBAVUIZZLOB-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000009818 secondary granulation Methods 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 238000003980 solgel method Methods 0.000 description 1
- 239000012798 spherical particle Substances 0.000 description 1
- 238000001694 spray drying Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910052984 zinc sulfide Inorganic materials 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Compounds Of Iron (AREA)
Abstract
The invention discloses a preparation method of high-performance stable ferric phosphate, which comprises the following steps: s1, iron oxide is put into preheated acid liquor, the acid liquor contains phosphoric acid and nitric acid, the molar ratio of the iron oxide to the acid liquor is 1 (8-20), the molar ratio of the phosphoric acid to the nitric acid is 2-2.5 (4-12), and the temperature and the stirring rate are controlled to react; s2, slowly dropwise adding an ammonia water solution while stirring, adjusting the pH value to 2-5, aging, filtering and washing; and S3, calcining, dehydrating, grinding and sieving the solid after washing the S2 to obtain the ferric phosphate powder. The method does not form iron phosphate complex and does not contain other impurities in the reaction process, high-purity iron phosphate can be obtained, the uniformity of the prepared iron phosphate product particles is high, the standard of battery-grade anhydrous iron phosphate for lithium iron phosphate is met, and the lithium iron phosphate battery prepared from the iron phosphate has excellent discharge efficiency.
Description
Technical Field
The invention relates to the technical field of lithium ion battery anode materials, in particular to high-performance stable ferric phosphate and a preparation method thereof.
Background
Ferric phosphate (FePO) 4 ) Also known as ferric orthophosphate, exists in nature in the form of wurtzite, fePO, often with 2 crystal waters 4 ·2H 2 O is an approximately white, pink or pale yellow powder. It has unique ion exchange capacity, catalytic properties and electrical properties. The structure and the appearance of the ferric phosphate serving as a raw material for synthesizing the lithium iron phosphate have great influence on the electrochemical performance of the lithium iron phosphate. Therefore, to prepare lithium iron phosphate with excellent performance, firstly, ferric phosphate with high performance stability is prepared.
Currently, fePO 4 The preparation method mainly comprises a sol-gel method, a hydrothermal method, a liquid phase precipitation method, a microwave method and the like. The iron phosphate may be classified into nano iron phosphate, microporous iron phosphate and mesoporous iron phosphate in terms of its size. In the prior art, various iron sources are mainly adopted to react with acid to prepare ferric phosphate, wherein the iron sources comprise iron powder, ferrous salt, ferric salt, pyrite, sulfuric acid dissolved ferrophosphorus slag, sulfuric acid dissolved pyrite and the like.
These current methods for synthesizing iron phosphate all suffer from various problems: (1) The iron source and the phosphate source are respectively introduced with impurity anions and impurity cations, and the production cost is greatly increased for removing the impurity anions. (2) The iron phosphate prepared by taking the simple substance iron as an iron source is of a layered structure, but a large amount of heat and flammable and explosive hydrogen are released when the iron powder reacts with the phosphoric acid, and the process is complex and difficult to control because of the addition of an oxidation step, so that the safety cost is high when the method is used for synthesizing a large amount of iron phosphate in industrial production. (3) Iron oxide reacts with phosphoric acid to obtain iron phosphate, and the iron phosphate forms a complex with phosphoric acid to stably exist in a solution, so that the iron phosphate is difficult to precipitate.
Therefore, it is necessary to develop a safe, low-cost, simple and easy-to-handle preparation method of high-purity lithium iron phosphate precursor iron phosphate.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention aims to provide the ferric phosphate with high performance stability and the preparation method thereof, which are used for preparing the ferric phosphate with high performance temperature by utilizing the reaction of ferric oxide with the mixed acid liquid of phosphoric acid and nitric acid, wherein the ferric phosphate complex is not formed in the reaction process, the ferric phosphate with high purity can be obtained, and the uniformity and consistency of the ferric phosphate product particles are high.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the invention provides a preparation method of high-performance stable ferric phosphate, which comprises the following steps:
s1, iron oxide is put into preheated acid liquor, the acid liquor contains phosphoric acid and nitric acid, the molar ratio of the iron oxide to the acid liquor is 1 (8-20), the molar ratio of the phosphoric acid to the nitric acid in the acid liquor is 2-2.5, (4-12), and the reaction is controlled at a certain temperature and stirring rate for a certain time;
s2, slowly dropwise adding an ammonia water solution while stirring, adjusting the pH value to 2-5, aging for a period of time, and performing suction filtration and washing;
and S3, calcining, dehydrating, grinding and sieving the solid after washing the S2 to obtain the ferric phosphate powder.
Further, the molar ratio of the ferric oxide to the acid liquor is 1 (8-12), and the molar ratio of phosphoric acid to nitric acid in the acid liquor is 2-2.2:6-8.
Further, the concentration of the phosphoric acid is 5% -30%.
Further, the stirring speed is 150-800r/min.
Further, the preheating temperature of the acid liquor is 40-60 ℃.
Further, the reaction temperature in the step S1 is 60-90 ℃;
preferably, the reaction temperature in S1 is 70-85 ℃.
Further, the reaction time in the step S1 is 15-240min;
preferably, the reaction time in S1 is 15-100min.
Further, the aging time in the step S2 is 1-12 hours;
preferably, the aging time is 3 to 8 hours.
Further, the calcination temperature in the step S3 is 600-5700 ℃;
and/or calcining for 1-5h; and/or the grinding mode in the step S3 is ball milling, and the grinding time is 15-180min.
The invention also provides the high-performance stable iron phosphate which is prepared by the preparation method, and the particle size of the iron phosphate is not more than 1-5 mu m.
Term interpretation:
iron phosphate complex: the iron phosphate-phosphoric acid complex formed by the iron phosphate and phosphoric acid exists in the form of a solution.
Iron phosphate dihydrate: iron phosphate dihydrate, which may also be referred to as ferric phosphate dihydrate, is an iron phosphate containing two crystal waters, and when precipitated from solution, the iron phosphate often contains 2 crystal waters.
Compared with the prior art, the invention has the beneficial effects that:
according to the preparation method of the high-performance stable ferric phosphate, the ferric phosphate with high-performance temperature is prepared by utilizing the reaction of ferric oxide with the mixed acid liquid of phosphoric acid and nitric acid, impurities such as a ferric phosphate complex and the like are not formed in the reaction process, high-purity ferric phosphate can be obtained, and anhydrous ferric phosphate with uniform size can be prepared, and the anhydrous ferric phosphate is spherical particles with the particle size not exceeding 1-5 mu m; the prepared ferric phosphate meets the standard of battery-grade anhydrous ferric phosphate for lithium iron phosphate, and can better ensure the first charge and discharge capacity and the first discharge efficiency when being used for preparing the lithium iron phosphate battery.
The preparation method has the advantages of simple process, no gas generation in the reaction process, low energy consumption, high safety, easy control and lower production cost.
Drawings
FIG. 1 is a scanning electron microscope image of iron sulfate prepared in example 1 of the present invention.
Detailed Description
The following describes the embodiments of the present disclosure further by way of specific examples, which are intended to describe the disclosure in detail, but not to limit the disclosure. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are intended to be within the scope of the present disclosure.
Example 1
The embodiment provides iron phosphate which is prepared by the following method:
s1, adding ferric oxide into a mixed solution which is preheated to 50 ℃ and contains phosphoric acid and nitric acid, wherein the molar ratio of the ferric oxide to the acid solution is 1:8, the mole ratio of phosphoric acid and nitric acid in the acid liquor is 2:6, the temperature is controlled to be 90 ℃, the stirring speed is 300r/min, and the reaction is carried out for 100min;
s2, slowly dropwise adding an ammonia water solution while stirring, adjusting the pH value to 2.5, aging for 2 hours, and carrying out suction filtration and washing;
and S3, calcining the solid after washing the S2 at 650 ℃ for 3 hours, ball-milling and sieving to obtain the ferric phosphate powder.
Example 2
The embodiment provides iron phosphate which is prepared by the following method:
s1, adding ferric oxide into a mixed solution which is preheated to 45 ℃ and contains phosphoric acid and nitric acid, wherein the molar ratio of the ferric oxide to the acid solution is 1:10, the mole ratio of phosphoric acid and nitric acid in the acid liquor is 2.2:7, the temperature is controlled to be 80 ℃, the stirring speed is 200r/min, and the reaction is carried out for 60min;
s2, slowly dropwise adding an ammonia water solution while stirring, adjusting the pH value to 2.0, aging for 3 hours, and carrying out suction filtration and washing;
and S3, calcining the solid after washing the S2 at 650 ℃ for 3.5 hours, ball-milling and sieving to obtain the ferric phosphate powder.
Example 3
The embodiment provides iron phosphate which is prepared by the following method:
s1, adding ferric oxide into a mixed solution which is preheated to 55 ℃ and contains phosphoric acid and nitric acid, wherein the molar ratio of the ferric oxide to the acid solution is 1:18, the mole ratio of phosphoric acid and nitric acid in the acid liquor is 2:10, the temperature is controlled to be 85 ℃, the stirring speed is 200r/min, and the reaction is carried out for 40min;
s2, slowly dropwise adding an ammonia water solution while stirring, adjusting the pH value to 2.0, aging for 4 hours, and performing suction filtration and washing;
and S3, calcining the solid after washing the S2 at 650 ℃ for 5 hours, ball-milling and sieving to obtain the ferric phosphate powder.
Example 4
The embodiment provides iron phosphate which is prepared by the following method:
s1, adding ferric oxide into a mixed solution which is preheated to 60 ℃ and contains phosphoric acid and nitric acid, wherein the molar ratio of the ferric oxide to the acid solution is 1:15, the mole ratio of phosphoric acid and nitric acid in the acid liquor is 2.5:12, the temperature is controlled to be 80 ℃, the stirring speed is 200r/min, and the reaction is carried out for 30min;
s2, slowly dropwise adding an ammonia water solution while stirring, adjusting the pH value to 2.0, aging for 3 hours, and carrying out suction filtration and washing;
and S3, calcining the solid after washing the S2 at 600 ℃ for 4 hours, ball-milling and sieving to obtain the ferric phosphate powder.
Example 5
The embodiment provides iron phosphate which is prepared by the following method:
s1, adding ferric oxide into a mixed solution which is preheated to 60 ℃ and contains phosphoric acid and nitric acid, wherein the molar ratio of the ferric oxide to the acid solution is 1:8, the mole ratio of phosphoric acid and nitric acid in the acid liquor is 2.1:7, the temperature is controlled to be 90 ℃, the stirring speed is 200r/min, and the reaction is carried out for 60min;
s2, slowly dropwise adding an ammonia water solution while stirring, adjusting the pH value to 2.0, aging for 3 hours, and carrying out suction filtration and washing;
and S3, calcining the solid after washing the S2 at 700 ℃ for 5 hours, ball-milling and sieving to obtain the ferric phosphate powder.
Comparative example 1
The comparative example provides an iron phosphate, which is prepared by the following method:
s1, putting ferric oxide into phosphoric acid liquid preheated to 50 ℃, wherein the molar ratio of the ferric oxide to phosphoric acid is 1:5, controlling the temperature to 90 ℃ and the stirring speed to 300r/min, and reacting for 100min;
s2, slowly dropwise adding an ammonia water solution while stirring, adjusting the pH value to 2.5, aging for 2 hours, and carrying out suction filtration and washing;
and S3, calcining the solid after washing the S2 at 650 ℃ for 3 hours, ball-milling and sieving to obtain the ferric phosphate powder.
Comparative example 2
The comparative example provides an iron phosphate, which is prepared by the following method:
s1, adding ferric oxide into a mixed solution which is preheated to 50 ℃ and contains phosphoric acid and nitric acid, wherein the molar ratio of the ferric oxide to the acid solution is 1:3, the mole ratio of phosphoric acid and nitric acid in the acid liquor is 4:1, the temperature is controlled to be 90 ℃, the stirring speed is 300r/min, and the reaction is carried out for 100min;
s2, slowly dropwise adding an ammonia water solution while stirring, adjusting the pH value to 2.5, aging for 2 hours, and carrying out suction filtration and washing;
and S3, calcining the solid after washing the S2 at 650 ℃ for 3 hours, ball-milling and sieving to obtain the ferric phosphate powder.
Comparative example 3
The comparative example provides an iron phosphate, which is prepared by the following method:
s1, adding ferric oxide into a mixed solution which is preheated to 60 ℃ and contains phosphoric acid and nitric acid, wherein the molar ratio of the ferric oxide to the acid solution is 1:25, wherein the mole ratio of phosphoric acid and nitric acid in the acid liquor is 2:1, the temperature is controlled to be 90 ℃, the stirring speed is 200r/min, and the reaction is carried out for 60min;
s2, slowly dropwise adding an ammonia water solution while stirring, adjusting the pH value to 2.0, aging for 3 hours, and carrying out suction filtration and washing;
and S3, calcining the solid after washing the S2 at 650 ℃ for 5 hours, ball-milling and sieving to obtain the ferric phosphate powder.
Comparative example 4
The comparative example provides an iron phosphate, which is prepared by the following method:
s1, adding ferric oxide into a mixed solution which is preheated to 50 ℃ and contains phosphoric acid and nitric acid, wherein the molar ratio of the ferric oxide to the acid solution is 1:8, the mole ratio of phosphoric acid and nitric acid in the acid liquor is 3:5, the temperature is controlled to be 50 ℃, the stirring speed is 200r/min, and the reaction is carried out for 10min;
s2, slowly dropwise adding an ammonia water solution while stirring, adjusting the pH value to 2.0, aging for 1h, and carrying out suction filtration and washing;
and S3, calcining the solid after washing the S2 at 650 ℃ for 5 hours, ball-milling and sieving to obtain the ferric phosphate powder.
Comparative example 5
The comparative example provides an iron phosphate, which is prepared by the following method:
s1, iron oxide is put into a mixed solution containing phosphoric acid and nitric acid, and the molar ratio of the iron oxide to the acid solution is 1:8, the mole ratio of phosphoric acid and nitric acid in the acid liquor is 6:2, the temperature is controlled to be 90 ℃, the stirring speed is 200r/min, and the reaction is carried out for 60min;
s2, slowly dropwise adding an ammonia water solution while stirring, adjusting the pH value to 6.5, aging for 3 hours, and carrying out suction filtration and washing;
and S3, calcining the solid after washing the S2 at 600 ℃ for 5 hours, ball-milling and sieving to obtain the ferric phosphate powder.
Comparative example 6
The comparative example provides an iron phosphate, which is prepared by the following method:
s1, adding ferric oxide into a mixed solution which is preheated to 55 ℃ and contains phosphoric acid and nitric acid, wherein the molar ratio of the ferric oxide to the acid solution is 1:10, the mole ratio of phosphoric acid and nitric acid in the acid liquor is 2:5, the temperature is controlled at 85 ℃, the stirring speed is 200r/min, the reaction is carried out for 40min, and the filtration and the washing are carried out;
s2, calcining the solid after washing in the step S1 at 650 ℃ for 5 hours, ball-milling and sieving to obtain the ferric phosphate powder.
Test examples
1. Morphology of iron phosphate
The morphology of the anhydrous iron phosphate obtained in example 1 was observed, and the scanning electron microscope images of both are shown in fig. 1. As can be seen from fig. 1: the anhydrous ferric phosphate obtained in the example 1 has uniform particle size and complete and uniform morphology, and the particle size of the ferric phosphate prepared by the invention is not more than 1-5 mu m.
2. Testing of phosphorus to iron ratio
1) Weighing 0.5g of ferric phosphate standard substance, dissolving, fixing the volume into a 100mL volumetric flask, and dividing 2mL of the solution into 100mL, and marking the solution A;
2) Weighing 0.5g of each of examples 1-5 and comparative examples 1-6, dissolving, respectively metering the dissolved materials into 100mL volumetric flasks, and respectively weighing 2mL of the dissolved materials to 100mL, and marking the dissolved materials as solutions B1-B5 and solutions C1-C6;
3) Taking A as a standard, and measuring the ratio of phosphorus to iron on an ICP to be 1:1;
4) And measuring B1-B5 solution and C1-C6 solution under the condition of taking A as a standard, and recording the phosphorus-iron ratio.
The measurement results are shown in Table 1.
TABLE 1 determination results of the phosphorus-iron ratios of the respective samples
Table 1 results show that the iron phosphate prepared in examples 1-5 of the present invention did not produce a complex.
3. Preparation of lithium iron phosphate
The lithium iron phosphate positive electrode materials were prepared by using the iron phosphate prepared by the preparation methods provided in examples 1 to 3, respectively, and the specific steps were as follows:
s1, mixing ferric phosphate and lithium hydroxide according to the mol ratio of L i/Fe=1.03 to prepare 150g, adding 3kg of butanol and deionized water to fully disperse for 6 hours, ball-milling for 8 hours, and spray-drying to obtain a granular material;
s2, putting the granular material into a granulator for secondary granulation, and then sintering in an inert atmosphere sintering furnace at 750 ℃ for 9 hours to obtain an initial lithium iron oxide anode material;
and S3, crushing the initial lithium iron phosphate positive electrode material to obtain the lithium iron phosphate positive electrode material.
Table 2 is an electrochemical performance test of lithium iron phosphate cathode materials synthesized from iron phosphate prepared by the preparation methods provided in examples 1 to 3, respectively.
The results in table 2 show that the iron phosphate prepared by the preparation method provided by the invention meets the standard of battery-grade anhydrous iron phosphate for lithium iron phosphate, and can better ensure the first charge and discharge capacity and the first discharge efficiency when being used for preparing lithium iron phosphate batteries.
In conclusion, the preparation method provided by the invention can be used for preparing the ferric phosphate with uniform particle size and few impurities (without containing the ferric phosphate complex), meets the standard of battery-grade anhydrous ferric phosphate for lithium iron phosphate, and has excellent discharge efficiency when the ferric phosphate prepared by the method is used for preparing the lithium iron phosphate battery.
Although embodiments of the present disclosure have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations may be made therein without departing from the principles and spirit of the disclosure, the scope of which is defined in the appended claims and their equivalents.
Claims (10)
1. The preparation method of the high-performance stable ferric phosphate is characterized by comprising the following steps of:
s1, iron oxide is put into preheated acid liquor, the acid liquor contains phosphoric acid and nitric acid, the molar ratio of the iron oxide to the acid liquor is 1 (8-20), the molar ratio of the phosphoric acid to the nitric acid in the acid liquor is 2-2.5, (4-12), and the reaction is controlled at a certain temperature and stirring rate for a certain time;
s2, slowly dropwise adding an ammonia water solution while stirring, adjusting the pH value to 2-5, aging for a period of time, and performing suction filtration and washing;
and S3, calcining, dehydrating, grinding and sieving the solid after washing the S2 to obtain the ferric phosphate powder.
2. The method for preparing high-performance stable ferric phosphate according to claim 1, wherein the molar ratio of the ferric oxide to the acid solution is 1 (8-12), and the molar ratio of phosphoric acid to nitric acid in the acid solution is 2-2.2:6-8.
3. The method for preparing high-performance stable iron phosphate according to claim 1, wherein the concentration of phosphoric acid is 5% -30%.
4. The method for preparing high-performance stable iron phosphate according to claim 1, wherein the stirring rate is 150-800r/min.
5. The method for preparing high-performance stable iron phosphate according to claim 1, wherein the preheating temperature of the acid solution is 40-60 ℃.
6. The method for preparing high-performance stable iron phosphate according to claim 1, wherein the reaction temperature in S1 is 60-90 ℃.
7. The method for preparing high-performance stable iron phosphate according to claim 1, wherein the reaction time in S1 is 15-240min.
8. The method for preparing high-performance stable iron phosphate according to claim 1, wherein the aging time in S2 is 1-12 hours.
9. The method for preparing high-performance stable iron phosphate according to claim 1, wherein the calcination temperature in S3 is 600-700 ℃; and/or calcining for 1-5h; and/or the grinding mode in the step S3 is ball milling, and the grinding time is 15-180min.
10. A high performance stable iron phosphate, characterized in that it is prepared by the preparation method according to any one of claims 1 to 9, the iron phosphate having a particle size of not more than 1 to 5 μm.
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| CN102468489A (en) * | 2010-11-18 | 2012-05-23 | 芯和能源股份有限公司 | Method for producing lithium iron phosphate material and lithium iron phosphate powder produced thereby |
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| CN111498823A (en) * | 2020-06-09 | 2020-08-07 | 艾姆新能源(江苏)有限公司 | Method for preparing battery-grade iron phosphate by using iron oxide |
| CN115340075A (en) * | 2022-05-18 | 2022-11-15 | 四川大学 | Method for preparing battery-grade iron phosphate by adopting iron oxide and dilute phosphoric acid |
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| CN102468489A (en) * | 2010-11-18 | 2012-05-23 | 芯和能源股份有限公司 | Method for producing lithium iron phosphate material and lithium iron phosphate powder produced thereby |
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| CN108565459A (en) * | 2016-03-18 | 2018-09-21 | 王海峰 | A kind of method that iron oxide modified prepares LiFePO4 |
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