CN116710400A - Electrode material for extracting lithium from salt lake by electrochemical deintercalation method, preparation method and application thereof - Google Patents
Electrode material for extracting lithium from salt lake by electrochemical deintercalation method, preparation method and application thereof Download PDFInfo
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- CN116710400A CN116710400A CN202380008412.7A CN202380008412A CN116710400A CN 116710400 A CN116710400 A CN 116710400A CN 202380008412 A CN202380008412 A CN 202380008412A CN 116710400 A CN116710400 A CN 116710400A
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- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 77
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 71
- 239000007772 electrode material Substances 0.000 title claims abstract description 53
- 238000000034 method Methods 0.000 title claims abstract description 18
- 238000002360 preparation method Methods 0.000 title abstract description 16
- 238000009831 deintercalation Methods 0.000 title abstract description 8
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 claims abstract description 63
- 229910021542 Vanadium(IV) oxide Inorganic materials 0.000 claims abstract description 51
- GRUMUEUJTSXQOI-UHFFFAOYSA-N vanadium dioxide Chemical compound O=[V]=O GRUMUEUJTSXQOI-UHFFFAOYSA-N 0.000 claims abstract description 51
- 238000000605 extraction Methods 0.000 claims abstract description 25
- 239000000463 material Substances 0.000 claims abstract description 25
- 239000003792 electrolyte Substances 0.000 claims abstract description 21
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910001416 lithium ion Inorganic materials 0.000 claims abstract description 15
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 58
- GNTDGMZSJNCJKK-UHFFFAOYSA-N divanadium pentaoxide Chemical compound O=[V](=O)O[V](=O)=O GNTDGMZSJNCJKK-UHFFFAOYSA-N 0.000 claims description 44
- 239000000203 mixture Substances 0.000 claims description 40
- 238000001354 calcination Methods 0.000 claims description 32
- 229910052799 carbon Inorganic materials 0.000 claims description 32
- 229910021389 graphene Inorganic materials 0.000 claims description 19
- 239000011230 binding agent Substances 0.000 claims description 15
- 239000006258 conductive agent Substances 0.000 claims description 15
- 238000001035 drying Methods 0.000 claims description 15
- 239000011248 coating agent Substances 0.000 claims description 12
- 238000000576 coating method Methods 0.000 claims description 12
- 239000012267 brine Substances 0.000 claims description 11
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims description 11
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 230000002950 deficient Effects 0.000 claims description 6
- 239000002904 solvent Substances 0.000 claims description 6
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 5
- 239000011261 inert gas Substances 0.000 claims description 5
- 239000002033 PVDF binder Substances 0.000 claims description 4
- 239000006260 foam Substances 0.000 claims description 4
- 239000012528 membrane Substances 0.000 claims description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 4
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 4
- 239000003115 supporting electrolyte Substances 0.000 claims description 4
- 239000006230 acetylene black Substances 0.000 claims description 3
- 125000000129 anionic group Chemical group 0.000 claims description 3
- 239000002041 carbon nanotube Substances 0.000 claims description 3
- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- 239000002245 particle Substances 0.000 claims description 3
- -1 polytetrafluoroethylene Polymers 0.000 claims description 3
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 3
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 3
- 150000003839 salts Chemical class 0.000 abstract description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 46
- 229910052757 nitrogen Inorganic materials 0.000 description 23
- 238000005245 sintering Methods 0.000 description 23
- 239000002002 slurry Substances 0.000 description 14
- 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 description 13
- 230000000052 comparative effect Effects 0.000 description 13
- 239000008103 glucose Substances 0.000 description 13
- 239000010410 layer Substances 0.000 description 13
- 229940116007 ferrous phosphate Drugs 0.000 description 12
- 238000000227 grinding Methods 0.000 description 12
- 229910000155 iron(II) phosphate Inorganic materials 0.000 description 12
- SDEKDNPYZOERBP-UHFFFAOYSA-H iron(ii) phosphate Chemical compound [Fe+2].[Fe+2].[Fe+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O SDEKDNPYZOERBP-UHFFFAOYSA-H 0.000 description 12
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 12
- 229910052808 lithium carbonate Inorganic materials 0.000 description 12
- 238000004321 preservation Methods 0.000 description 12
- 238000003795 desorption Methods 0.000 description 7
- 239000011247 coating layer Substances 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 238000001179 sorption measurement Methods 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 2
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000009830 intercalation Methods 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 229910001415 sodium ion Inorganic materials 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- FOIXSVOLVBLSDH-UHFFFAOYSA-N Silver ion Chemical compound [Ag+] FOIXSVOLVBLSDH-UHFFFAOYSA-N 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 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 description 1
- 229910002090 carbon oxide Inorganic materials 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000011534 incubation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- GCICAPWZNUIIDV-UHFFFAOYSA-N lithium magnesium Chemical compound [Li].[Mg] GCICAPWZNUIIDV-UHFFFAOYSA-N 0.000 description 1
- 229910003002 lithium salt Inorganic materials 0.000 description 1
- 159000000002 lithium salts Chemical class 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000002468 redox effect Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 238000010532 solid phase synthesis reaction Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
Abstract
The application discloses an electrode material for extracting lithium from salt lakes by an electrochemical deintercalation method, a preparation method and application thereof, wherein the electrode material comprises a core and a shell layer coated on the surface of the core, the core comprises lithium iron phosphate, and the shell layer comprises vanadium dioxide. According to the application, the vanadium dioxide is coated on the surface of the lithium iron phosphate material, after the lithium extraction operation is performed, the electrolyte is heated to 68-90 ℃ and then the lithium removal step is performed, so that the conductivity of the electrode can be improved, the current density of the electrode is increased, and therefore, the intercalated lithium ions are accelerated to be removed into the electrolyte, and the lithium extraction efficiency is improved.
Description
Technical Field
The application relates to the technical field of electrode materials, in particular to an electrode material for extracting lithium from salt lake by an electrochemical deintercalation method, a preparation method and application thereof.
Background
Lithium is an important strategic metal, is widely applied to various fields of energy, chemical industry, electronics, metallurgy, medicine and the like, and is praised as 'new energy metal in 21 st century'. In recent years, with the rapid development of the new energy automobile field and the energy storage industry, the demand of lithium has been increasing. At present, ore lithium extraction and salt lake lithium extraction are main sources. Wherein the lithium resource reserve of the salt lake brine accounts for 65% of the total global quantity. The lithium raw materials required for the production of global lithium salt products are mostly derived from salt lakes, and the quality of salt lakes is reduced year by year with the development of high-quality salt lake resources. The lithium resources of salt lakes in plateau areas (such as Qinghai-Tibet plateau) are rich, but most of the salt lakes have high magnesium-lithium ratio, and the utilization difficulty of the lithium resources is relatively high. Lithium ion battery materials are increasingly used for extracting lithium from salt lakes due to the redox properties of transition metals and the reversible cycle deintercalation properties of lithium, and the strong adaptability to salt lakes. Therefore, in order to realize green and efficient extraction of lithium in salt lake brine, it is particularly necessary to develop an electrode material with excellent conductivity, which is beneficial to improving the lithium extraction efficiency.
In view of this, the present application has been made.
Disclosure of Invention
The application aims to provide an electrode material for extracting lithium from a salt lake by an electrochemical deintercalation method, a preparation method and application thereof, and solves the problem that the existing lithium iron phosphate electrode material has lower lithium extraction efficiency when being applied to extracting lithium from the salt lake.
The application is realized in the following way:
in a first aspect, the present application provides an electrode material comprising a core and a shell layer coated on the surface of the core, wherein the core comprises lithium iron phosphate, and the shell layer comprises vanadium dioxide.
In an alternative embodiment, the vanadium dioxide is present in an amount of 0.5wt% to 3wt%.
In an alternative embodiment, carbon is further included in the shell layer, and the mass ratio of the vanadium dioxide to the carbon is 1:2.1-5.5.
In an alternative embodiment, the particle size of the electrode material is 100-800nm.
In an alternative embodiment, the shell layer has a thickness of 1-10nm.
In a second aspect, the present application provides a method for preparing an electrode material according to the foregoing embodiment, including coating a shell layer containing vanadium dioxide on a surface of lithium iron phosphate.
In an alternative embodiment, the method comprises calcining a mixture of lithium iron phosphate, vanadium pentoxide, and a carbon source to produce a lithium iron phosphate material having a surface coated with vanadium dioxide.
In an alternative embodiment, the calcination is performed under an inert gas atmosphere.
In an alternative embodiment, the carbon source is at least one of elemental carbon or organic carbon.
In an alternative embodiment, the carbon source is graphene.
In an alternative embodiment, the calcination time is 4-6 hours, and the temperature is maintained for 1.5-2.5 hours after calcination.
In an alternative embodiment, the calcination temperature is 700-800 ℃.
In a third aspect, the present application provides an electrode comprising a conductive agent, a binder, and an electrode material according to any one of the preceding embodiments.
In an alternative embodiment, the mass ratio of the conductive agent, the binder and the electrode material is 0.5 to 1.5:0.5-1.5:8.
in an alternative embodiment, the conductive agent is at least one of acetylene black, conductive carbon black, graphene, and carbon nanotubes.
In an alternative embodiment, the binder is at least one of polyvinylidene fluoride and polytetrafluoroethylene.
In a fourth aspect, the present application provides a method for preparing an electrode, comprising coating a slip comprising a conductive agent, a binder and an electrode material according to any one of the preceding embodiments onto a current collector, and drying to obtain a lithium iron phosphate electrode.
In an alternative embodiment, the solvent, the conductive agent, the binder and the electrode material are mixed, ground, slurried, coated on a current collector, and vacuum dried to obtain the lithium iron phosphate electrode.
In an alternative embodiment, the lithium iron phosphate electrode is used as an anode, foam nickel is used as a cathode, naCl is used as a supporting electrolyte, and the lithium iron phosphate electrode in an under-lithium state is obtained by electrifying and delithiating.
In a fifth aspect, the present application provides an application of the electrode according to the foregoing embodiment in extracting lithium from brine.
In a sixth aspect, the present application provides an electrochemical lithium extraction device with an electrode according to the previous embodiment, comprising:
an electrode comprising the lithium iron phosphate electrode in the under-lithium state of the foregoing embodiment as a cathode electrode, and/or the lithium iron phosphate electrode of the foregoing embodiment as an anode electrode;
an anode chamber for containing a lithium-deficient electrolyte;
a cathode chamber for containing a lithium-rich electrolyte;
anionic membrane: for separating the anode and cathode compartments.
In a seventh aspect, the present application provides an electrochemical lithium extraction method comprising extracting lithium and/or delithiating:
applying voltage between the cathode and the anode of the electrochemical lithium extraction device in the previous embodiment to extract lithium, so that lithium ions in brine are inserted into the lithium iron phosphate electrode in a underlithium state;
and/or delithiation, applying voltage between the cathode and the anode of the electrochemical lithium extraction device according to the previous embodiment and heating the lithium-deficient electrolyte to 68-90 ℃ to release lithium ions intercalated in the lithium iron phosphate electrode.
The application has the following beneficial effects:
according to the application, by utilizing the characteristic that vanadium dioxide is an excellent electric conductor at the temperature of more than 68 ℃, the lithium extraction operation is carried out by coating vanadium dioxide on the surface of the lithium iron phosphate material, and then the lithium removal step is carried out after the electrolyte is heated to more than 68 ℃, so that the conductivity of the electrode can be improved, the current density of the electrode is increased, and the intercalated lithium ions are accelerated to be removed into the electrolyte, so that the lithium extraction efficiency is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 shows Li in an anolyte at the time of desorption in Experimental example 1, experimental example 8, and comparative Experimental example 1 + Concentration variation.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
Some embodiments of the present application provide an electrode material including a core including lithium iron phosphate and a shell layer coated on a surface of the core including vanadium dioxide.
According to the method disclosed by the application, the surface of the lithium iron phosphate material is coated with vanadium dioxide, after conventional lithium extraction operation is performed, the electrolyte is heated to more than 68 ℃ and then the lithium removal step is performed, so that the conductivity of the electrode can be improved, the current density of the electrode is increased, and therefore, the intercalated lithium ions are accelerated to be removed into the electrolyte, and the lithium extraction efficiency is improved.
In some alternative embodiments, the vanadium dioxide may be present in an amount of 0.5wt% to 3wt%, specifically any of 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, or 0.5wt% to 3wt%, although vanadium dioxide has excellent conductivity above 68 ℃, it is not desirable to add too much because of its poor conductivity at lower temperatures.
In some alternative embodiments, the shell layer further includes carbon, where the mass ratio of vanadium dioxide to carbon is 1:2.1-5.5, specifically may be any of 1:2.1, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, or 1:2.1-5.5, and although vanadium dioxide has good electrical conductivity above 68 ℃, carbon may be included in the coating layer due to poor electrical conductivity of vanadium dioxide at lower temperatures, which improves the electrical conductivity of the shell layer, especially at lower temperatures.
In some alternative embodiments, the particle size of the electrode material is 100-800nm.
In some alternative embodiments, the thickness of the shell layer is 1-10nm, the thickness of the shell layer is too small, the coating amount of vanadium dioxide is low, and the improvement on the conductivity is limited; the thickness of the shell layer is too large, the lithium ion deintercalation path is too long, and the difficulty of lithium ion deintercalation can be increased.
Another embodiment of the present application provides a method for preparing an electrode material according to the foregoing embodiment, including coating a shell layer containing vanadium dioxide on a surface of lithium iron phosphate.
In some alternative embodiments, the method includes calcining a mixture of lithium iron phosphate, vanadium pentoxide, and a carbon source to produce a lithium iron phosphate material coated with vanadium dioxide.
Because the melting point of vanadium dioxide is higher, the vanadium dioxide can be melted at more than approximately two thousand ℃, and the calcining difficulty is high, the vanadium dioxide is not directly used for coating lithium iron phosphate, but vanadium pentoxide and a carbon source are used as raw materials, and the carbon is used for reducing the vanadium pentoxide into the vanadium dioxide at a higher temperature to generate carbon oxide.
The lithium iron phosphate can be prepared in a conventional manner, for example, a solid-phase method, a liquid-phase method and the like, the phosphorus source, the iron source, the lithium source and the carbon source are uniformly mixed in proportion, and the mixture slurry is dried in a blast furnace and then calcined under the protection of inert gas.
The mixing in this embodiment may be conventional, such as ball milling, or may be performed in a particular manner, such as by using a solvent to prepare a suspension, so that the lithium iron phosphate, vanadium pentoxide, and carbon source are more thoroughly mixed.
In some alternative embodiments, the calcination is performed under an inert gas atmosphere, avoiding oxidation of the material.
In some alternative embodiments, the carbon source is at least one of elemental carbon or organic carbon, for example, may be graphite, graphene, glucose, etc., preferably graphene.
In some alternative embodiments, the calcination temperature may be 700-800 ℃, specifically 700 ℃, 710 ℃, 720 ℃, 730 ℃, 740 ℃, 750 ℃, 760 ℃, 770 ℃, 780 ℃, 790 ℃, 800 ℃, or any value between 700-800 ℃, and too high a calcination temperature may cause problems such as structural collapse.
In some alternative embodiments, the calcination time is 4-6h, in particular may be any of 4h, 5h, 6h or 4-6h, preferably 5h, and the incubation is 1.5-2.5h, preferably 2h, after calcination. The calcination time is too long, which may cause the problems of collapse of the structure and the like, and the heat preservation is beneficial to the stability of the material structure.
Another embodiment of the present application provides an electrode comprising a conductive agent, a binder, and an electrode material according to any one of the preceding embodiments.
In some embodiments, the mass ratio of the conductive agent, binder, and electrode material is 0.5 to 1.5:0.5-1.5:8, preferably 1:1:8.
in some embodiments, the conductive agent is at least one of acetylene black, conductive carbon black, graphene, and carbon nanotubes;
in some embodiments, the binder is at least one of polyvinylidene fluoride and polytetrafluoroethylene.
Another embodiment of the present application provides a method for preparing an electrode, comprising coating a slip containing a conductive agent, a binder, and the electrode material according to any one of the preceding embodiments on a current collector, and drying to obtain a lithium iron phosphate electrode.
In some alternative embodiments, the solvent, the conductive agent, the binder and the electrode material are mixed, ground, slurried, coated on a current collector, and vacuum dried to obtain the lithium iron phosphate electrode embodiment, wherein the solvent may be N-methyl pyrrolidone.
In some alternative embodiments, the lithium iron phosphate electrode is used as an anode, foam nickel is used as a cathode, naCl is used as a supporting electrolyte, and the lithium iron phosphate electrode in an underlithium state is obtained by electrifying and delithiating, specifically, a direct current voltage of 1.0V can be applied between the cathode and the anode, and the lithium is electrolytically delithiated.
Another embodiment of the present application provides an electrode material or an electrode according to the previous embodiment for extracting lithium from brine.
Another embodiment of the present application provides an electrochemical lithium extraction device with the electrode of the previous embodiment, comprising:
an electrode comprising the lithium iron phosphate electrode in the under-lithium state of the foregoing embodiment as a cathode electrode, and/or the lithium iron phosphate electrode of the foregoing embodiment as an anode electrode;
an anode chamber for containing a lithium-deficient electrolyte;
a cathode chamber for containing a lithium-rich electrolyte;
anionic membrane: for separating the anode and cathode compartments.
Another embodiment of the present application provides an electrochemical lithium extraction method comprising extracting lithium and delithiating;
applying voltage between the cathode and the anode of the electrochemical lithium extraction device in the previous embodiment to extract lithium, so that lithium ions in brine are inserted into the lithium iron phosphate electrode in a underlithium state;
and removing lithium, namely applying voltage between the cathode and the anode of the electrochemical lithium extraction device and heating the poor lithium electrolyte to 68 ℃ or higher to remove lithium ions intercalated in the lithium iron phosphate electrode.
The temperature of the lithium-deficient electrolyte is too low to quickly heat the electrode to more than 68 ℃, the conductivity of the electrode is poor, but the stability of the electrode structure can be affected due to the too high temperature, and the requirements on materials used for the silver ion membrane, the cathode chamber and the anode chamber are high, so that the temperature of the lithium-deficient electrolyte is not higher than 90 ℃.
The features and capabilities of the present application are described in further detail below in connection with the examples.
Example 1:
the preparation method of the lithium iron phosphate electrode material coated with vanadium dioxide comprises the following steps:
151.85g of ferrous phosphate, 37.45g of lithium carbonate and 12.98g of glucose are weighed, mixed and ground. And (3) drying the mixture slurry in a blast furnace, crushing and grinding, sintering under the protection of nitrogen, calcining at 700 ℃ for 10 hours, and preserving the heat for 6 hours. After the materials obtained by sintering are crushed and sieved, 3.28g of vanadium pentoxide and 7.18g of graphene are added to be uniformly mixed, the mixture is placed in a tube furnace, nitrogen is introduced, the mixture is calcined for 5 hours at 750 ℃, and the heat preservation time is 2 hours.
Example 2:
the content of the coated vanadium dioxide was 0.5wt% as compared with example 1.
The preparation method of the lithium iron phosphate electrode material coated with vanadium dioxide comprises the following steps:
151.85g of ferrous phosphate, 37.45g of lithium carbonate and 12.98g of glucose are weighed, mixed and ground. And (3) drying the mixture slurry in a blast furnace, crushing and grinding, sintering under the protection of nitrogen, calcining at 700 ℃ for 10 hours, and preserving the heat for 6 hours. After the materials obtained by sintering are crushed and sieved, 1.07g of vanadium pentoxide and 7.18g of graphene are added to be uniformly mixed, the mixture is placed in a tube furnace, nitrogen is introduced, the mixture is calcined for 5 hours at 750 ℃, and the heat preservation time is 2 hours.
Example 3:
the content of the coated vanadium dioxide was 3wt% as compared with example 1.
The preparation method of the lithium iron phosphate electrode material coated with vanadium dioxide comprises the following steps:
151.85g of ferrous phosphate, 37.45g of lithium carbonate and 12.98g of glucose are weighed, mixed and ground. And (3) drying the mixture slurry in a blast furnace, crushing and grinding, sintering under the protection of nitrogen, calcining at 700 ℃ for 10 hours, and preserving the heat for 6 hours. After the materials obtained by sintering are crushed and sieved, 6.38g of vanadium pentoxide and 7.18g of graphene are added to be uniformly mixed, the mixture is placed in a tube furnace, nitrogen is introduced, the mixture is calcined for 5 hours at 750 ℃, and the heat preservation time is 2 hours.
Example 4:
in comparison with example 1, the mass ratio of vanadium pentoxide to carbon was 1:2.
The preparation method of the lithium iron phosphate electrode material coated with vanadium dioxide comprises the following steps:
151.85g of ferrous phosphate, 37.45g of lithium carbonate and 12.98g of glucose are weighed, mixed and ground. And (3) drying the mixture slurry in a blast furnace, crushing and grinding, sintering under the protection of nitrogen, calcining at 700 ℃ for 10 hours, and preserving the heat for 6 hours. After the materials obtained by sintering are crushed and sieved, 3.28g of vanadium pentoxide and 6.56g of graphene are added to be uniformly mixed, the mixture is placed in a tube furnace, nitrogen is introduced, the mixture is calcined for 5 hours at 750 ℃, and the heat preservation time is 2 hours.
Example 5:
in comparison with example 1, the mass ratio of vanadium pentoxide to carbon was 1:5.
The preparation method of the lithium iron phosphate electrode material coated with vanadium dioxide comprises the following steps:
151.85g of ferrous phosphate, 37.45g of lithium carbonate and 12.98g of glucose are weighed, mixed and ground. And (3) drying the mixture slurry in a blast furnace, crushing and grinding, sintering under the protection of nitrogen, calcining at 700 ℃ for 10 hours, and preserving the heat for 6 hours. After the materials obtained by sintering are crushed and sieved, 3.28g of vanadium pentoxide and 16.4g of graphene are added to be uniformly mixed, the mixture is placed in a tube furnace, nitrogen is introduced, the mixture is calcined for 5 hours at 750 ℃, and the heat preservation time is 2 hours.
Example 6:
the calcination temperature was 700℃compared with example 1.
The preparation method of the lithium iron phosphate electrode material coated with vanadium dioxide comprises the following steps:
151.85g of ferrous phosphate, 37.45g of lithium carbonate and 12.98g of glucose are weighed, mixed and ground. And (3) drying the mixture slurry in a blast furnace, crushing and grinding, sintering under the protection of nitrogen, calcining at 700 ℃ for 10 hours, and preserving the heat for 6 hours. After the materials obtained by sintering are crushed and sieved, 3.28g of vanadium pentoxide and 6.56g of graphene are added to be uniformly mixed, the mixture is placed in a tube furnace, nitrogen is introduced, the mixture is calcined for 5 hours at 700 ℃, and the heat preservation time is 2 hours.
Example 7:
the calcination temperature was 800℃compared with example 1.
The preparation method of the lithium iron phosphate electrode material coated with vanadium dioxide comprises the following steps:
151.85g of ferrous phosphate, 37.45g of lithium carbonate and 12.98g of glucose are weighed, mixed and ground. And (3) drying the mixture slurry in a blast furnace, crushing and grinding, sintering under the protection of nitrogen, calcining at 700 ℃ for 10 hours, and preserving the heat for 6 hours. After the materials obtained by sintering are crushed and sieved, 3.28g of vanadium pentoxide and 6.56g of graphene are added to be uniformly mixed, the mixture is placed in a tube furnace, nitrogen is introduced, the mixture is calcined for 5 hours at 800 ℃, and the heat preservation time is 2 hours.
Comparative example 1:
in comparison with example 1, no vanadium dioxide was coated.
151.85g of ferrous phosphate, 37.45g of lithium carbonate and 12.98g of glucose are weighed, mixed and ground. The mixture slurry is dried in a blast furnace, crushed and ground, sintered under the protection of inert gas, calcined at 700 ℃ for 12 hours and kept for 10 hours. After the materials obtained by sintering are crushed and sieved, 7.18g of graphene is added to be uniformly mixed, the mixture is placed in a tube furnace, nitrogen is introduced, the mixture is calcined at 650 ℃ for 8 hours, and the heat preservation time is 2 hours.
Comparative example 2:
the content of the coated vanadium dioxide was 0.1wt% as compared with example 1.
The preparation method of the lithium iron phosphate electrode material coated with vanadium dioxide comprises the following steps:
151.85g of ferrous phosphate, 37.45g of lithium carbonate and 12.98g of glucose are weighed, mixed and ground. And (3) drying the mixture slurry in a blast furnace, crushing and grinding, sintering under the protection of nitrogen, calcining at 700 ℃ for 10 hours, and preserving the heat for 6 hours. After crushing and sieving the material obtained by sintering, adding 0.22g of vanadium pentoxide and 7.18g of graphene, uniformly mixing, placing in a tube furnace, introducing nitrogen, calcining for 5 hours at 750 ℃, and preserving the heat for 2 hours.
Comparative example 3:
the content of the coated vanadium dioxide was 5wt% as compared with example 1.
The preparation method of the lithium iron phosphate electrode material coated with vanadium dioxide comprises the following steps:
151.85g of ferrous phosphate, 37.45g of lithium carbonate and 12.98g of glucose are weighed, mixed and ground. And (3) drying the mixture slurry in a blast furnace, crushing and grinding, sintering under the protection of nitrogen, calcining at 700 ℃ for 10 hours, and preserving the heat for 6 hours. After the materials obtained by sintering are crushed and sieved, 10.7g of vanadium pentoxide and 7.18g of graphene are added to be uniformly mixed, the mixture is placed in a tube furnace, nitrogen is introduced, the mixture is calcined for 5 hours at 750 ℃, and the heat preservation time is 2 hours.
Comparative example 4:
in comparison with example 1, the mass ratio of vanadium pentoxide to carbon was 1:1.
The preparation method of the lithium iron phosphate electrode material coated with vanadium dioxide comprises the following steps:
151.85g of ferrous phosphate, 37.45g of lithium carbonate and 12.98g of glucose are weighed, mixed and ground. And (3) drying the mixture slurry in a blast furnace, crushing and grinding, sintering under the protection of nitrogen, calcining at 700 ℃ for 10 hours, and preserving the heat for 6 hours. After the materials obtained by sintering are crushed and sieved, 3.28g of vanadium pentoxide and 3.28g of graphene are added to be uniformly mixed, the mixture is placed in a tube furnace, nitrogen is introduced, the mixture is calcined for 5 hours at 750 ℃, and the heat preservation time is 2 hours.
Comparative example 5:
in comparison with example 1, the mass ratio of vanadium pentoxide to carbon was 1:8.
The preparation method of the lithium iron phosphate electrode material coated with vanadium dioxide comprises the following steps:
151.85g of ferrous phosphate, 37.45g of lithium carbonate and 12.98g of glucose are weighed, mixed and ground. And (3) drying the mixture slurry in a blast furnace, crushing and grinding, sintering under the protection of nitrogen, calcining at 700 ℃ for 10 hours, and preserving the heat for 6 hours. After the materials obtained by sintering are crushed and sieved, 3.28g of vanadium pentoxide and 26.24g of graphene are added to be uniformly mixed, the mixture is placed in a tube furnace, nitrogen is introduced, the mixture is calcined for 5 hours at 750 ℃, and the heat preservation time is 2 hours.
Experimental example:
mixing the lithium iron phosphate materials obtained in the examples 1-7 and the comparative examples 1-5, PVDF and conductive carbon black according to the mass ratio of 8:1:1, taking N-methyl pyrrolidone as a solvent, fully grinding and mixing, uniformly coating on a current collector (the coating area of the slurry is 1cm multiplied by 1 cm), and then drying in a vacuum drying oven at 90 ℃ for 12 hours. And (3) taking the prepared lithium iron phosphate electrode as an anode, taking foam nickel as a cathode and taking 1.0mol/L NaCl as a supporting electrolyte, and carrying out electrolytic lithium removal under the direct-current voltage of 1.0V until the current is lower than 2mA/g to obtain the under-lithium electrode material.
The simulated brine is adopted as source liquid (the components are shown in table 1), the materials are adopted as positive electrodes, a carbon rod is adopted as a negative electrode, and the voltage range between the two electrodes is 1.0V for primary adsorption. Subsequently, the electrolyte was heated to 80 ℃, and the adsorption saturated lithium iron phosphate electrode was placed in the anode chamber of the electrolysis apparatus, and desorption was performed once by applying a constant current of 1.0V.
Comparative experimental example:
in comparison with the experimental example, the electrolyte was not heated during delithiation.
Experimental example 1, experimental example 8 (Experimental example corresponding to comparative example 1) the brine composition before and after treatment of comparative example 1 is shown in Table 1, li in the anolyte at the time of desorption + The concentration changes are shown in fig. 1, and the content of the intercalation element in the desorption 0h electrode and the concentration of the lithium in the desorption 4h anolyte in each experimental example and comparative experimental example are shown in table 2.
Table 1 brine composition before and after treatment
TABLE 2 desorption of the content of intercalating elements in the 0h electrode and desorption of the 4h anolyte lithium concentration
From the above experimental data, the lithium concentration of the anolyte of the experimental examples of examples 1 to 7 is higher than that of the experimental examples of comparative examples 1 to 5, because the vanadium dioxide coating layer of the specific content range of the experimental examples can generate high conductivity at the temperature of more than 68 ℃, thereby rapidly desorbing lithium ions; the sodium ion content of examples 1-3 was lower relative to that of comparative example 1 because examples 1-3 had lower current at adsorption and lower adsorbed sodium ion content. Experimental example 1 has a reduced efficiency of absorbing lithium ions compared to experimental example 8, but at the same time, adsorption of impurity ions is reduced.
The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.
Industrial applicability
The inventor utilizes the characteristic that vanadium dioxide is an excellent electric conductor at the temperature of more than 68 ℃, and by coating vanadium dioxide on the surface of the lithium iron phosphate material, after the lithium extraction operation is carried out, the electrolyte is heated to more than 68 ℃ and then the lithium removal step is carried out, so that the conductivity of the electrode can be improved, the current density of the electrode is increased, and the intercalated lithium ions are accelerated to be removed into the electrolyte, and the lithium extraction efficiency is improved.
In order to solve the problem that the conductivity of vanadium dioxide is poor at a lower temperature, carbon is introduced into the coating layer, the conductivity of the shell layer is improved, particularly the conductivity at a lower temperature, and in the process of preparing the coating layer, a carbon source can also be used as a reducing agent to reduce vanadium pentoxide into vanadium dioxide, so that the problem that the melting point of the vanadium dioxide is too high and the vanadium dioxide is difficult to melt and coat on the core is solved, and the difficulty and cost of industrial application are greatly reduced.
Claims (22)
1. An electrode material is characterized by comprising a core and a shell layer coated on the surface of the core, wherein the core comprises lithium iron phosphate, and the shell layer comprises vanadium dioxide.
2. The electrode material according to claim 1, wherein the content of vanadium dioxide is 0.5wt% to 3wt%.
3. The electrode material of claim 1, wherein carbon is further included in the shell layer, and the mass ratio of vanadium dioxide to carbon is 1:2-5.5.
4. The electrode material according to claim 1, wherein the particle size of the electrode material is 100-800nm.
5. The electrode material according to claim 1, wherein the shell layer has a thickness of 1-10nm.
6. A method for producing an electrode material according to any one of claims 1 to 5, comprising coating a shell layer containing vanadium dioxide on the surface of lithium iron phosphate.
7. The method for producing an electrode material according to claim 6, comprising calcining a mixture of lithium iron phosphate, vanadium pentoxide and a carbon source to obtain a lithium iron phosphate material coated with vanadium dioxide on the surface.
8. The method for producing an electrode material according to claim 7, wherein the carbon source is at least one of elemental carbon or organic carbon.
9. The method for producing an electrode material according to claim 7, wherein the carbon source is graphene.
10. The method for producing an electrode material according to claim 7, wherein the calcination step is performed under an inert gas atmosphere.
11. The method for producing an electrode material according to claim 7, wherein the temperature of the calcining step is 700 to 800 ℃.
12. The method for preparing an electrode material according to claim 7, wherein the calcination step is performed for 4 to 6 hours, and the temperature is maintained for 1.5 to 2.5 hours after calcination.
13. A lithium iron phosphate electrode comprising a conductive agent, a binder and an electrode material according to any one of claims 1 to 12.
14. The lithium iron phosphate electrode of claim 13, wherein the mass ratio of the conductive agent, binder and electrode material is 0.5-1.5:0.5-1.5:8.
15. the lithium iron phosphate electrode of claim 13, wherein the conductive agent is at least one of acetylene black, conductive carbon black, graphene, and carbon nanotubes.
16. The lithium iron phosphate electrode of claim 13, wherein the binder is at least one of polyvinylidene fluoride and polytetrafluoroethylene.
17. A method for preparing an electrode, comprising coating a slip comprising a conductive agent, a binder and the electrode material of any one of claims 1-12 on a current collector, and drying to obtain a lithium iron phosphate electrode.
18. The method for preparing an electrode according to claim 17, wherein the solvent, the conductive agent, the binder and the electrode material are mixed, ground, slurried, coated on a current collector, and vacuum-dried to obtain the lithium iron phosphate electrode.
19. The method for preparing the electrode according to claim 17, wherein the lithium iron phosphate electrode is used as an anode, foam nickel is used as a cathode, naCl is used as a supporting electrolyte, and the lithium iron phosphate electrode in an under-lithium state is obtained by electrifying and delithiating.
20. Use of an electrode according to any one of claims 13 to 19 in brine extraction of lithium.
21. An electrochemical lithium extraction device, comprising:
an electrode comprising the lithium iron phosphate electrode of claim 19 in an under-lithium state as a cathode electrode, and/or the lithium iron phosphate electrode of any one of claims 13-18 as an anode electrode;
an anode chamber for containing a lithium-deficient electrolyte;
a cathode chamber for containing a lithium-rich electrolyte;
anionic membrane: for separating the anode and cathode compartments.
22. An electrochemical lithium extraction method is characterized by comprising the steps of extracting lithium and/or removing lithium,
extracting lithium, namely applying voltage between a cathode and an anode of the electrochemical lithium extracting device of claim 21 to enable lithium ions in brine to be inserted into the lithium iron phosphate electrode in a underlithium state;
and/or delithiation, applying a voltage between the cathode and the anode of the electrochemical lithium extraction device of claim 21 and heating the lithium-depleted electrolyte to 68-90 ℃ to strip lithium ions intercalated in the lithium iron phosphate electrode.
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