CN115849327A - Lithium manganese iron phosphate cathode material and preparation method thereof - Google Patents
Lithium manganese iron phosphate cathode material and preparation method thereof Download PDFInfo
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- CN115849327A CN115849327A CN202211618903.7A CN202211618903A CN115849327A CN 115849327 A CN115849327 A CN 115849327A CN 202211618903 A CN202211618903 A CN 202211618903A CN 115849327 A CN115849327 A CN 115849327A
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- DVATZODUVBMYHN-UHFFFAOYSA-K lithium;iron(2+);manganese(2+);phosphate Chemical compound [Li+].[Mn+2].[Fe+2].[O-]P([O-])([O-])=O DVATZODUVBMYHN-UHFFFAOYSA-K 0.000 title claims abstract description 43
- 238000002360 preparation method Methods 0.000 title claims abstract description 26
- 239000010406 cathode material Substances 0.000 title claims description 20
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 56
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 26
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 26
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 26
- 229910052742 iron Inorganic materials 0.000 claims abstract description 26
- 239000007774 positive electrode material Substances 0.000 claims abstract description 21
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 15
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 14
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 14
- 239000011574 phosphorus Substances 0.000 claims abstract description 14
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims abstract description 12
- 239000010405 anode material Substances 0.000 claims abstract description 12
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 12
- 239000011572 manganese Substances 0.000 claims abstract description 12
- 239000000843 powder Substances 0.000 claims abstract description 11
- 238000010438 heat treatment Methods 0.000 claims abstract description 10
- 239000000463 material Substances 0.000 claims abstract description 8
- 238000001035 drying Methods 0.000 claims abstract description 7
- 238000005245 sintering Methods 0.000 claims abstract description 7
- 238000001238 wet grinding Methods 0.000 claims abstract description 7
- 230000001681 protective effect Effects 0.000 claims abstract description 5
- 229910015645 LiMn Inorganic materials 0.000 claims abstract description 4
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 claims abstract description 4
- 238000002156 mixing Methods 0.000 claims abstract description 4
- 238000005303 weighing Methods 0.000 claims abstract description 4
- CUGMJFZCCDSABL-UHFFFAOYSA-N arsenic(3+);trisulfide Chemical compound [S-2].[S-2].[S-2].[As+3].[As+3] CUGMJFZCCDSABL-UHFFFAOYSA-N 0.000 claims description 27
- 238000000034 method Methods 0.000 claims description 13
- 239000000203 mixture Substances 0.000 claims description 9
- 239000002245 particle Substances 0.000 claims description 8
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 6
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 6
- SNKMVYBWZDHJHE-UHFFFAOYSA-M lithium;dihydrogen phosphate Chemical compound [Li+].OP(O)([O-])=O SNKMVYBWZDHJHE-UHFFFAOYSA-M 0.000 claims description 6
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 claims description 5
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 4
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 4
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 claims description 4
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 claims description 4
- IIPYXGDZVMZOAP-UHFFFAOYSA-N lithium nitrate Chemical compound [Li+].[O-][N+]([O-])=O IIPYXGDZVMZOAP-UHFFFAOYSA-N 0.000 claims description 4
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 3
- 229910000388 diammonium phosphate Inorganic materials 0.000 claims description 3
- 235000019838 diammonium phosphate Nutrition 0.000 claims description 3
- 238000010902 jet-milling Methods 0.000 claims description 3
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims description 3
- 229910052808 lithium carbonate Inorganic materials 0.000 claims description 3
- 235000006748 manganese carbonate Nutrition 0.000 claims description 3
- 239000011656 manganese carbonate Substances 0.000 claims description 3
- 229940093474 manganese carbonate Drugs 0.000 claims description 3
- 229910000016 manganese(II) carbonate Inorganic materials 0.000 claims description 3
- XMWCXZJXESXBBY-UHFFFAOYSA-L manganese(ii) carbonate Chemical compound [Mn+2].[O-]C([O-])=O XMWCXZJXESXBBY-UHFFFAOYSA-L 0.000 claims description 3
- CWQXQMHSOZUFJS-UHFFFAOYSA-N molybdenum disulfide Chemical compound S=[Mo]=S CWQXQMHSOZUFJS-UHFFFAOYSA-N 0.000 claims description 3
- 229910052717 sulfur Inorganic materials 0.000 claims description 3
- 239000011593 sulfur Substances 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 239000004254 Ammonium phosphate Substances 0.000 claims description 2
- 229910021578 Iron(III) chloride Inorganic materials 0.000 claims description 2
- 229910021380 Manganese Chloride Inorganic materials 0.000 claims description 2
- GLFNIEUTAYBVOC-UHFFFAOYSA-L Manganese chloride Chemical compound Cl[Mn]Cl GLFNIEUTAYBVOC-UHFFFAOYSA-L 0.000 claims description 2
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 2
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 claims description 2
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 claims description 2
- 229910000148 ammonium phosphate Inorganic materials 0.000 claims description 2
- 235000019289 ammonium phosphates Nutrition 0.000 claims description 2
- REKWWOFUJAJBCL-UHFFFAOYSA-L dilithium;hydrogen phosphate Chemical compound [Li+].[Li+].OP([O-])([O-])=O REKWWOFUJAJBCL-UHFFFAOYSA-L 0.000 claims description 2
- 229960004887 ferric hydroxide Drugs 0.000 claims description 2
- 238000000227 grinding Methods 0.000 claims description 2
- CPSYWNLKRDURMG-UHFFFAOYSA-L hydron;manganese(2+);phosphate Chemical compound [Mn+2].OP([O-])([O-])=O CPSYWNLKRDURMG-UHFFFAOYSA-L 0.000 claims description 2
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 claims description 2
- KAEAMHPPLLJBKF-UHFFFAOYSA-N iron(3+) sulfide Chemical compound [S-2].[S-2].[S-2].[Fe+3].[Fe+3] KAEAMHPPLLJBKF-UHFFFAOYSA-N 0.000 claims description 2
- IEECXTSVVFWGSE-UHFFFAOYSA-M iron(3+);oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Fe+3] IEECXTSVVFWGSE-UHFFFAOYSA-M 0.000 claims description 2
- HEJPGFRXUXOTGM-UHFFFAOYSA-K iron(3+);triiodide Chemical compound [Fe+3].[I-].[I-].[I-] HEJPGFRXUXOTGM-UHFFFAOYSA-K 0.000 claims description 2
- 229910001386 lithium phosphate Inorganic materials 0.000 claims description 2
- 235000002867 manganese chloride Nutrition 0.000 claims description 2
- 239000011565 manganese chloride Substances 0.000 claims description 2
- 229940099607 manganese chloride Drugs 0.000 claims description 2
- 229940099596 manganese sulfate Drugs 0.000 claims description 2
- 235000007079 manganese sulphate Nutrition 0.000 claims description 2
- 239000011702 manganese sulphate Substances 0.000 claims description 2
- MIVBAHRSNUNMPP-UHFFFAOYSA-N manganese(2+);dinitrate Chemical compound [Mn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MIVBAHRSNUNMPP-UHFFFAOYSA-N 0.000 claims description 2
- RGVLTEMOWXGQOS-UHFFFAOYSA-L manganese(2+);oxalate Chemical compound [Mn+2].[O-]C(=O)C([O-])=O RGVLTEMOWXGQOS-UHFFFAOYSA-L 0.000 claims description 2
- SQQMAOCOWKFBNP-UHFFFAOYSA-L manganese(II) sulfate Chemical compound [Mn+2].[O-]S([O-])(=O)=O SQQMAOCOWKFBNP-UHFFFAOYSA-L 0.000 claims description 2
- 235000019837 monoammonium phosphate Nutrition 0.000 claims description 2
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 claims description 2
- 235000011007 phosphoric acid Nutrition 0.000 claims description 2
- FEONEKOZSGPOFN-UHFFFAOYSA-K tribromoiron Chemical compound Br[Fe](Br)Br FEONEKOZSGPOFN-UHFFFAOYSA-K 0.000 claims description 2
- TWQULNDIKKJZPH-UHFFFAOYSA-K trilithium;phosphate Chemical compound [Li+].[Li+].[Li+].[O-]P([O-])([O-])=O TWQULNDIKKJZPH-UHFFFAOYSA-K 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 3
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 3
- DOCYQLFVSIEPAG-UHFFFAOYSA-N [Mn].[Fe].[Li] Chemical compound [Mn].[Fe].[Li] DOCYQLFVSIEPAG-UHFFFAOYSA-N 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 7
- 239000000126 substance Substances 0.000 description 6
- 229910052785 arsenic Inorganic materials 0.000 description 4
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 4
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- ILXAVRFGLBYNEJ-UHFFFAOYSA-K lithium;manganese(2+);phosphate Chemical compound [Li+].[Mn+2].[O-]P([O-])([O-])=O ILXAVRFGLBYNEJ-UHFFFAOYSA-K 0.000 description 3
- 239000002243 precursor Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 2
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical group [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000004146 energy storage Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 239000010450 olivine Substances 0.000 description 1
- 229910052609 olivine Inorganic materials 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000003980 solgel method Methods 0.000 description 1
- 238000010532 solid phase synthesis reaction Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
Images
Abstract
The invention discloses a lithium iron manganese phosphate positive electrode material and a preparation method thereof, and relates to the technical field of lithium ion batteries. The preparation method of the lithium iron manganese phosphate anode material comprises the following steps: (1) According to LiMn x Fe 1‑x PO 4 Weighing a lithium source, a manganese source, a phosphorus source and an iron source according to the stoichiometric ratio of medium lithium, manganese, iron and phosphorus, wherein x is more than or equal to 0.1 and less than or equal to 0.8; (2) Mixing the lithium source, the manganese source, the phosphorus source, the iron source and the reducing agent, carrying out wet grinding, and then drying to obtain powder; the reducing agent contains a reducing agent A which is sublimated at 500-800 ℃ and has reducibility in the temperature range, and also contains or does not contain a carbon source; (3) Heating the powder to 400-500 ℃ under the protective atmosphere, preserving the heat for 0.5-2 h, then heating to 500-800 ℃, and sintering for 5-12 h to obtain the lithium iron manganese phosphateA pole material. The lithium iron manganese phosphate anode material has higher gram capacity.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a lithium manganese iron phosphate positive electrode material and a preparation method thereof.
Background
The lithium iron phosphate as a widely used lithium battery anode material has the advantages of low price, long cycle life and the like. With the wide application of the energy storage battery, the defects of the energy storage battery are gradually exposed, such as low working voltage, low battery energy density and the like, and the endurance requirement of people on new energy automobiles cannot be met. Therefore, how to further improve the energy density is the key point of research on modification of the lithium iron phosphate material.
The lithium manganese phosphate is a material with an ordered olivine structure, the theoretical specific capacity of the lithium manganese phosphate is the same as that of lithium iron phosphate, but the discharge platform is higher than that of the lithium iron phosphate, and the lithium manganese phosphate has the advantage of potential high energy density. And has the characteristics of high stability and safety. At present, many methods are available for synthesizing lithium iron manganese phosphate cathode materials, such as a sol-gel method, a liquid phase method, a high temperature solid phase method, and the like. In the method, ferrous iron is mostly adopted as an iron source, but the ferrous iron source is very unstable and is very easy to oxidize, multivalent mixing is easy to form during preparation of the precursor, the stoichiometric ratio of the iron source is influenced, and protective gas needs to be introduced and a certain amount of reducing agent needs to be added during preparation of the precursor. CN102738465B is directly reduced by carbon in the preparation process, thus avoiding the use of hydrogen, ammonia or other mixed gases. And the carbon source is added during sintering, and the coating effect can be achieved, so that the preparation process and the carbon coating are completed in one step. However, when carbon is directly used as a reducing agent, excessive carbon coating is easily caused, and the gram-volume capacity of the battery is affected.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a lithium iron manganese phosphate positive electrode material and a preparation method thereof.
In order to realize the purpose, the technical scheme adopted by the invention is as follows:
a preparation method of a lithium iron manganese phosphate positive electrode material comprises the following steps:
(1) According to LiMn x Fe 1-x PO 4 Weighing a lithium source, a manganese source, a phosphorus source and an iron source according to the stoichiometric ratio of medium lithium, manganese, iron and phosphorus, wherein x is more than or equal to 0.1 and less than or equal to 0.8;
(2) Mixing the lithium source, the manganese source, the phosphorus source, the iron source and the reducing agent, carrying out wet grinding, and then drying to obtain powder; the reducing agent contains a reducing agent A which is sublimated at 500-800 ℃ and has reducibility in the temperature range, and also contains or does not contain a carbon source, wherein the iron source is ferric iron;
(3) And heating the powder to 400-500 ℃ under the protective atmosphere, preserving the heat for 0.5-2 h, then heating to 500-800 ℃, and sintering for 5-12 h to obtain the lithium iron manganese phosphate anode material.
According to the invention, by selecting the substance which is sublimated at 500-800 ℃ and has reducibility in the temperature range as the reducing agent, the phenomenon that impurities remain on the surface of the positive electrode material due to excessive use amount, the conductivity of the positive electrode material is influenced, and the gram capacity of the battery is reduced can be avoided. The ferric iron is stable and does not influence the stoichiometric ratio of the product.
Preferably, the reducing agent A is at least one of arsenic sulfide, molybdenum sulfide and sulfur. Further preferably, the reducing agent a is arsenic sulfide. Arsenic sulfide can be slowly decomposed to generate reducing substances, so that the stability and uniformity of iron and manganese valence states in the reaction process are ensured; the arsenic sulfide is converted into a gaseous state after being heated, so that the material can generate a porous structure, the contact between the material and an electrolyte is facilitated, and the electrochemical performance is improved; in addition, the doping of a small amount of arsenic can improve the conductivity of the cathode material; the redundant arsenic sulfide can be directly removed by controlling the temperature, no impurity residue exists, the method is simple and efficient, and the problem that the gram volume is easily reduced by using carbon as a reducing agent in the prior art is solved.
Preferably, the amount of the substance of the carbon source is a, the amount of the substance of the reducing agent A is b, the amount of the substance of the iron is c, (a +3 b) c =1 (1-1.5); b = (0-0.3): 0.3-0.5). More preferably, a: b = (0.1-0.3): 0.3-0.5), two components of carbon and arsenic sulfide are selected as reducing agents to greatly improve the conductivity of the cathode material, the carbon and arsenic can form a multiple conductive network, the use amount of the carbon and arsenic and the proportion of the carbon and arsenic to iron are limited to avoid the incomplete reduction problem, and the gram capacity of the cathode material can be improved.
Preferably, the lithium source is at least one of lithium carbonate, lithium hydroxide, lithium phosphate, lithium chloride, lithium nitrate, lithium dihydrogen phosphate and lithium dihydrogen phosphate; the manganese source is at least one of manganese phosphate, manganese oxalate, manganese carbonate, manganese chloride, manganese sulfate and manganese nitrate; the phosphorus source is at least one of phosphoric acid, ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, lithium dihydrogen phosphate and lithium hydrogen phosphate; the iron source is at least one of ferric oxide, ferric nitrate, ferric chloride, ferric iodide, ferric bromide, ferric sulfide and ferric hydroxide.
Preferably, in the step (2), the wet grinding method is: adding water, ethanol or a mixture thereof into a mixture of a lithium source, a manganese source, a phosphorus source, an iron source and a reducing agent, carrying out wet grinding, and stopping grinding when the particle size of the powder is less than 5 mu m; the drying conditions are as follows: drying for 5-12 h at 50-65 deg.C under vacuum.
Preferably, in the step (3), the temperature is raised to 400-500 ℃ at the rate of 5-10 ℃/min, and the temperature is raised to 500-800 ℃ at the rate of 1-5 ℃/min.
Preferably, in the step (3), after sintering, performing jet milling on the product to obtain the lithium iron manganese phosphate anode material, wherein the particle size D10 of the lithium iron manganese phosphate anode material is more than or equal to 0.4 μm, and the particle size D50: 0.5-0.8 μm, and D90 is less than or equal to 1 μm.
In addition, the invention also discloses a lithium iron manganese phosphate positive electrode material prepared by the method.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, substances which are sublimated at 600-800 ℃ and have reducibility are selected as reducing agents, so that the valence states of iron and manganese can be stabilized in the preparation process of the lithium iron manganese phosphate anode material, and other impurities cannot be remained on the surface of the prepared anode material; the battery prepared by the anode material has higher gram capacity.
Drawings
Fig. 1 is a flow chart of the preparation of the lithium iron manganese phosphate positive electrode material of the present invention.
Detailed Description
To better illustrate the objects, aspects and advantages of the present invention, the present invention will be further described with reference to the accompanying drawings and specific embodiments.
Example 1
In an embodiment of the lithium iron manganese phosphate cathode material of the present invention, a preparation process of the cathode material is shown in fig. 1, and the preparation method includes:
(1) According to LiMn 0.2 Fe 0.8 PO 4 Weighing 0.05mol of battery-grade lithium carbonate, 0.02mol of analytically pure manganese carbonate, 0.04mol of analytically pure iron oxide and 0.1mol of battery-grade diammonium hydrogen phosphate according to the stoichiometric ratio of medium lithium, manganese, iron and phosphorus elements;
(2) Adding the components and 0.04mol of arsenic sulfide into a mixture of deionized water and ethanol with the volume ratio of 1;
(3) Heating the precursor powder to 400 ℃ under a protective atmosphere at a heating rate of 5 ℃/min, and keeping the temperature for 1h; then heating to 800 ℃, wherein the heating rate is 5 ℃/min, and sintering for 10h to obtain powder;
(4) And (4) performing jet milling on the powder in the step (3), and controlling the particle size D10 to be more than or equal to 0.4 mu m, the particle size D50 to be 0.5-0.8 mu m and the particle size D90 to be less than or equal to 1 mu m to obtain the lithium iron manganese phosphate anode material.
Example 2
In an embodiment of the lithium iron manganese phosphate positive electrode material of the present invention, the preparation method of the lithium iron manganese phosphate positive electrode material is different from that in embodiment 1 only in that arsenic sulfide is replaced with molybdenum sulfide.
Example 3
In an embodiment of the lithium iron manganese phosphate cathode material of the present invention, the preparation method of the lithium iron manganese phosphate cathode material is different from that in embodiment 1 only in that arsenic sulfide is replaced with sulfur.
Example 4
The preparation method of the lithium iron manganese phosphate cathode material is different from that of the embodiment 1 in that in the step (2), arsenic sulfide is replaced by a mixture of carbon and arsenic sulfide, and the ratio of the amounts of carbon, arsenic sulfide and iron is 0.1.
Example 5
The preparation method of the lithium iron manganese phosphate cathode material is different from that of the embodiment 1 in that in the step (2), arsenic sulfide is replaced by a mixture of carbon and arsenic sulfide, and the ratio of the amounts of carbon, arsenic sulfide and iron is 1.
Example 6
The preparation method of the lithium iron manganese phosphate cathode material is different from that of the embodiment 1 in that in the step (2), arsenic sulfide is replaced by a mixture of carbon and arsenic sulfide, and the ratio of the amounts of carbon, arsenic sulfide and iron is 3.
Example 7
The preparation method of the lithium iron manganese phosphate cathode material is different from that of the embodiment 1 in that in the step (2), arsenic sulfide is replaced by a mixture of carbon and arsenic sulfide, and the ratio of the amounts of carbon, arsenic sulfide and iron is 0.4.
Comparative example 1
The preparation method of the lithium iron manganese phosphate cathode material is different from that of the cathode material in embodiment 1 only in that citric acid is used for replacing arsenic sulfide.
Comparative example 2
A lithium iron manganese phosphate cathode material, which is different from that in example 1 only in that carbon is used instead of arsenic sulfide.
The examples and comparative examples were subjected to the following performance tests, and the test results are shown in table 1.
And (3) preparing the lithium iron manganese phosphate anode material into a button cell, testing the charge-discharge cycle performance, controlling the charge-discharge voltage range to be 2.5-4.5V and the charge-discharge current to be 0.1C, and recording the first charge gram capacity.
TABLE 1
| Item | Gram capacity (mAh/g) |
| Example 1 | 160.2 |
| Example 2 | 157.3 |
| Example 3 | 157.5 |
| Example 4 | 162.9 |
| Example 5 | 162.8 |
| Example 6 | 163.1 |
| Example 7 | 153.2 |
| Comparative example 1 | 148.2 |
| Comparative example 2 | 149.8 |
As can be seen from Table 1, the gram capacities of the lithium iron manganese phosphate positive electrode materials in the embodiments 1 to 7 can all reach more than 150mAh/g, and the results show that the lithium iron manganese phosphate positive electrode material is beneficial to improving the energy density of the battery and is suitable for being applied to the preparation of the lithium ion battery. In comparative examples 1-2, the carbon source was used as the reducing agent and the gram volume was significantly lower than that of the present invention.
As a result of the tests of comparative examples 1 to 3, it was found that the gram capacity of the battery can be improved by selecting arsenic sulfide as the reducing agent. The test results of comparing example 1 with examples 4 to 6 show that the gram capacity of the battery can be synergistically improved by selecting two components of carbon and arsenic sulfide as reducing agents.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the protection scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.
Claims (10)
1. A preparation method of a lithium iron manganese phosphate positive electrode material is characterized by comprising the following steps:
(1) According to LiMn x Fe 1-x PO 4 Weighing a lithium source, a manganese source, a phosphorus source and an iron source according to the stoichiometric ratio of medium lithium, manganese, iron and phosphorus, wherein x is more than or equal to 0.1 and less than or equal to 0.8;
(2) Mixing the lithium source, the manganese source, the phosphorus source, the iron source and a reducing agent, carrying out wet grinding, and then drying to obtain powder; the reducing agent contains a reducing agent A which is sublimated at 500-800 ℃ and has reducibility in the temperature range, and also contains or does not contain a carbon source;
(3) And heating the powder to 400-500 ℃ under the protective atmosphere, preserving the heat for 0.5-2 h, then heating to 500-800 ℃, and sintering for 5-12 h to obtain the lithium iron manganese phosphate anode material.
2. The method for preparing the lithium iron manganese phosphate cathode material according to claim 1, wherein the reducing agent a is at least one of arsenic sulfide, molybdenum sulfide and sulfur.
3. The method for preparing the lithium iron manganese phosphate cathode material according to claim 2, wherein the reducing agent a is arsenic sulfide.
4. The method for producing a lithium iron manganese phosphate positive electrode material according to claim 3, wherein the amount of the carbon source material is a, the amount of the reducing agent A material is b, the amount of the iron material is c, and (a +3 b) c =1 (1-1.5); b = (0-0.3): 0.3-0.5).
5. The method for preparing the lithium iron manganese phosphate cathode material according to claim 4, wherein a: b = (0.1-0.3): (0.3-0.5).
6. The method for preparing a lithium iron manganese phosphate positive electrode material according to claim 1, wherein the lithium source is at least one of lithium carbonate, lithium hydroxide, lithium phosphate, lithium chloride, lithium nitrate, lithium dihydrogen phosphate, and lithium dihydrogen phosphate; the manganese source is at least one of manganese phosphate, manganese oxalate, manganese carbonate, manganese chloride, manganese sulfate and manganese nitrate; the phosphorus source is at least one of phosphoric acid, ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, lithium dihydrogen phosphate and dilithium hydrogen phosphate; the iron source is at least one of ferric oxide, ferric nitrate, ferric chloride, ferric iodide, ferric bromide, ferric sulfide and ferric hydroxide.
7. The preparation method of the lithium iron manganese phosphate positive electrode material as claimed in claim 1, wherein in the step (2), the wet grinding method comprises the following steps: adding water, ethanol or a mixture thereof into a mixture of a lithium source, a manganese source, a phosphorus source, an iron source and a reducing agent, carrying out wet grinding, and stopping grinding when the particle size of the powder is less than 5 mu m; the drying conditions are as follows: drying for 5-12 h at 50-65 deg.C under vacuum.
8. The method for preparing the lithium iron manganese phosphate positive electrode material according to claim 1, wherein in the step (3), the temperature is raised to 400 to 500 ℃ at a rate of 5 to 10 ℃/min, and the temperature is raised to 500 to 800 ℃ at a rate of 1 to 5 ℃/min.
9. The preparation method of the lithium iron manganese phosphate positive electrode material of claim 1, wherein in the step (3), the product is subjected to jet milling after sintering is completed to obtain the lithium iron manganese phosphate positive electrode material, and the particle size D10 of the lithium iron manganese phosphate positive electrode material is not less than 0.4 μm, D50: 0.5-0.8 μm, and D90 is less than or equal to 1 μm.
10. A lithium iron manganese phosphate positive electrode material prepared by the method according to any one of claims 1 to 9.
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| US6200704B1 (en) * | 1998-09-01 | 2001-03-13 | Polyplus Battery Company, Inc. | High capacity/high discharge rate rechargeable positive electrode |
| CN102738465A (en) * | 2012-07-20 | 2012-10-17 | 重庆大学 | Preparation method of lithium iron manganese phosphate cathode composite material |
| CN113620344A (en) * | 2021-08-05 | 2021-11-09 | 松山湖材料实验室 | Compound for prelithiation and preparation method thereof, positive electrode prelithiation material and preparation method thereof, and lithium battery |
| CN114665058A (en) * | 2022-05-05 | 2022-06-24 | 盐城工学院 | Preparation method of lithium ion battery anode material lithium iron manganese phosphate |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6200704B1 (en) * | 1998-09-01 | 2001-03-13 | Polyplus Battery Company, Inc. | High capacity/high discharge rate rechargeable positive electrode |
| CN102738465A (en) * | 2012-07-20 | 2012-10-17 | 重庆大学 | Preparation method of lithium iron manganese phosphate cathode composite material |
| CN113620344A (en) * | 2021-08-05 | 2021-11-09 | 松山湖材料实验室 | Compound for prelithiation and preparation method thereof, positive electrode prelithiation material and preparation method thereof, and lithium battery |
| CN114665058A (en) * | 2022-05-05 | 2022-06-24 | 盐城工学院 | Preparation method of lithium ion battery anode material lithium iron manganese phosphate |
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