CN116779860A - Positive electrode material, preparation method thereof, positive electrode and sodium ion battery - Google Patents
Positive electrode material, preparation method thereof, positive electrode and sodium ion battery Download PDFInfo
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- 239000007774 positive electrode material Substances 0.000 title claims abstract description 44
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 title claims abstract description 19
- 238000002360 preparation method Methods 0.000 title claims abstract description 19
- 229910001415 sodium ion Inorganic materials 0.000 title claims abstract description 19
- YPPMLCHGJUMYPZ-UHFFFAOYSA-L sodium;iron(2+);sulfate Chemical compound [Na+].[Fe+2].[O-]S([O-])(=O)=O YPPMLCHGJUMYPZ-UHFFFAOYSA-L 0.000 claims abstract description 60
- 239000002270 dispersing agent Substances 0.000 claims abstract description 43
- 239000002243 precursor Substances 0.000 claims abstract description 35
- 239000002245 particle Substances 0.000 claims abstract description 27
- 239000011734 sodium Substances 0.000 claims abstract description 26
- 239000000463 material Substances 0.000 claims abstract description 24
- 229920000642 polymer Polymers 0.000 claims abstract description 20
- 229910052708 sodium Inorganic materials 0.000 claims abstract description 18
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims abstract description 17
- 238000005245 sintering Methods 0.000 claims abstract description 14
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 claims abstract description 12
- 229910000360 iron(III) sulfate Inorganic materials 0.000 claims abstract description 12
- 238000002156 mixing Methods 0.000 claims abstract description 11
- 239000000084 colloidal system Substances 0.000 claims abstract description 10
- 239000002105 nanoparticle Substances 0.000 claims abstract description 8
- 238000001035 drying Methods 0.000 claims abstract description 6
- 239000000243 solution Substances 0.000 claims description 41
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 23
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 23
- 235000011152 sodium sulphate Nutrition 0.000 claims description 23
- 239000011790 ferrous sulphate Substances 0.000 claims description 15
- 235000003891 ferrous sulphate Nutrition 0.000 claims description 15
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 15
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims description 15
- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 claims description 8
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical compound [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 7
- 238000001694 spray drying Methods 0.000 claims description 6
- 229920002401 polyacrylamide Polymers 0.000 claims description 5
- 239000012298 atmosphere Substances 0.000 claims description 4
- 229920002635 polyurethane Polymers 0.000 claims description 4
- 239000004814 polyurethane Substances 0.000 claims description 4
- 239000002994 raw material Substances 0.000 claims description 4
- 229920002125 Sokalan® Polymers 0.000 claims description 3
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 claims description 3
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 3
- 239000011259 mixed solution Substances 0.000 claims description 3
- 239000004584 polyacrylic acid Substances 0.000 claims description 3
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 claims description 3
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 239000010405 anode material Substances 0.000 abstract description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 24
- 229910052742 iron Inorganic materials 0.000 description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 8
- 239000002041 carbon nanotube Substances 0.000 description 7
- 229910021393 carbon nanotube Inorganic materials 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 6
- 239000003792 electrolyte Substances 0.000 description 6
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 4
- 229920000447 polyanionic polymer Polymers 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 238000011161 development Methods 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 229910052720 vanadium Inorganic materials 0.000 description 3
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 2
- 239000011149 active material Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 239000010406 cathode material Substances 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- XPPKVPWEQAFLFU-UHFFFAOYSA-J diphosphate(4-) Chemical compound [O-]P([O-])(=O)OP([O-])([O-])=O XPPKVPWEQAFLFU-UHFFFAOYSA-J 0.000 description 2
- 235000011180 diphosphates Nutrition 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000008187 granular material Substances 0.000 description 2
- 229920003063 hydroxymethyl cellulose Polymers 0.000 description 2
- 229940031574 hydroxymethyl cellulose Drugs 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 235000021317 phosphate Nutrition 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 239000011787 zinc oxide Substances 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- 229910004563 Na2Fe2 (SO4)3 Inorganic materials 0.000 description 1
- 229910019398 NaPF6 Inorganic materials 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 239000012300 argon atmosphere Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 239000006258 conductive agent Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000012983 electrochemical energy storage Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 231100000086 high toxicity Toxicity 0.000 description 1
- 238000009766 low-temperature sintering Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 238000006864 oxidative decomposition reaction Methods 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 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
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 229910001428 transition metal ion Inorganic materials 0.000 description 1
- 238000009827 uniform distribution Methods 0.000 description 1
- 229910001928 zirconium oxide Inorganic materials 0.000 description 1
Abstract
The invention relates to the technical field of battery materials, and discloses a positive electrode material, a preparation method thereof, a positive electrode and a sodium ion battery. The positive electrode material comprises particles of sodium iron sulfate serving as a base material and three-dimensional conductive network structures embedded into the sodium iron sulfate particles and distributed on the surfaces of the sodium iron sulfate particles, wherein the three-dimensional conductive network structures are composed of AZO nano particles. The preparation method of the positive electrode material comprises the following steps: uniformly mixing AZO, a polymer dispersing agent with a chain structure and a sodium ferric sulfate precursor solution to prepare a colloid solution; drying the colloid solution and sintering at 300-460 deg.c. The positive electrode is prepared by adopting the positive electrode material. Sodium ion battery, including the above-mentioned positive electrode. The anode material provided by the invention has better electrochemical performance.
Description
Technical Field
The invention relates to the technical field of sodium ion battery materials, in particular to a positive electrode material and a preparation method thereof, a positive electrode and a sodium ion battery.
Background
The development of sustainable energy has been an important trend in energy development because of the problem of energy shortage. Sodium ion batteries become one of the important electrochemical energy storage candidates because of the abundant raw material resources and low cost.
Currently, the positive electrode materials of sodium ion batteries are mainly classified into three types, namely layered oxides, polyanions and Prussian white derivative materials. Among them, the polyanion material has been attracting attention because the polyanion polyhedron and the transition metal ion polyhedron are connected by strong covalent bonds to form a three-dimensional network structure, which has excellent structural stability and long cycle potential.
Current polyanionic materials mainly comprise: vanadium-based phosphates (NaVPO) 4 F、Na 3 V 2 (PO 4 ) 3 Etc.), iron-based pyrophosphate (Na 2 FeP 2 O 7 、Na 3.32 Fe 2.34 (P 2 O 7 ) 2 Etc.), iron-based sulfate (Na x Fe y (SO 4 ) z ，Na 2 Fe 2 (SO 4 ) 3 Etc.). The vanadium-based phosphate has higher working potential (4.0V vs. Na+/Na), but the vanadium element has high toxicity and high price, and the practical application is limited. The iron-based polyanion type positive electrode material has rich iron content, is environment-friendly and has rapid development. Wherein, the working potential of the iron-based pyrophosphate anode material is lower (about 3.0V vs. Na+/Na), and the energy density is lower. And the iron-based sulfate material has a higher working potential (about 3.7V vs. Na+/Na) and can bring higher energy density, so that the iron-based sulfate material is concerned.
However, the material has high working voltage, and the upper limit of charging voltage exceeds 4.2V vs. Na+/Na, which is easy to cause the oxidative decomposition of electrolyte at the positive electrode. In addition, such iron-based sulfates are generally poor in conductivity, resulting in low sodium storage capacity and poor rate capability. Meanwhile, when the material contacts with air, the material is easy to absorb water and oxidize, so that the material is invalid. In addition, since iron-based sulfate is decomposed at a temperature exceeding 500 ℃ and cannot be treated by conventional high-temperature carbon coating means, carbon nanotube-based materials are generally used for compounding to improve conductivity. However, carbon nanotubes have a large specific surface area, are easily agglomerated, and have poor dispersion effects. Therefore, more carbon nanotubes are usually required, and the addition amount is usually >5%, which is expensive.
In addition, since the iron-based sulfate has a high operating potential, the upper limit of the charging voltage is usually higher than 4.2v vs. na+/Na, and the electrolyte is easily oxidized and decomposed on the surface of the iron-based sulfate at the voltage. Conventional methods for improving high voltage stability are to use oxide composites such as zinc oxide, aluminum oxide, zirconium oxide, titanium oxide, etc. But these oxides are generally non-conductive. Aiming at the low conductivity of sodium iron sulfate, the adoption of the insulating oxide composite material can further reduce the conductivity of the material, and reduce the capacity and the rate capability.
In view of this, the present invention has been made.
Disclosure of Invention
The present invention aims to provide a positive electrode material and a preparation method thereof, a positive electrode and a sodium ion battery, and aims to improve at least one of the problems mentioned in the background art.
The invention is realized in the following way:
in a first aspect, the present invention provides a positive electrode material, wherein the particles of the positive electrode material comprise sodium iron sulfate particles as a base material and three-dimensional conductive network structures embedded into the sodium iron sulfate particles and distributed on the surfaces of the sodium iron sulfate particles, and the three-dimensional conductive network structures are formed by AZO nano particles.
In an alternative embodiment, the mass ratio of the sodium iron sulfate to the AZO in the positive electrode material is 100:0.5-10;
preferably, the mass ratio of the sodium iron sulfate to the AZO in the positive electrode material is 100 (2-8).
In a second aspect, the present invention provides a method for preparing a positive electrode material, comprising:
uniformly mixing AZO, a polymer dispersing agent with a chain structure and a sodium ferric sulfate precursor solution to prepare a colloid solution;
drying the colloid solution and sintering at 300-460 deg.c in inert atmosphere.
In an alternative embodiment, the colloidal solution is dried by spray drying.
In an alternative embodiment, the method for uniformly mixing AZO, the polymeric dispersant and the sodium iron sulfate precursor solution comprises the following steps:
and mixing AZO, a high molecular dispersing agent and a sodium ferric sulfate precursor solution, and then sanding.
In an alternative embodiment, the mass ratio of the sodium iron sulfate precursor solution to the AZO and the high molecular dispersing agent is 100 (0.5-10): 0.1-5);
preferably, the mass ratio of the sodium iron sulfate precursor in the sodium iron sulfate precursor solution to the AZO and the polymer dispersing agent is 100 (2-8) (0.1-1).
In an alternative embodiment, the sodium iron sulfate precursor solution is a mixed solution of ferrous sulfate and sodium sulfate, the mass concentration of the sodium iron sulfate precursor solution is 10-50%, and the molar ratio of the ferrous sulfate to the sodium sulfate is 1.5-2.5:1.
In an alternative embodiment, the polymeric dispersant having a chain structure is selected from at least one of polyacrylic acid, sodium polyacrylate, polyacrylamide, sodium carboxymethyl cellulose, and polyurethane.
In a third aspect, the present invention provides a positive electrode produced from a raw material including the positive electrode material of the foregoing embodiment or the positive electrode material produced by the production method of any one of the foregoing embodiments.
In a fourth aspect, the present invention provides a sodium ion battery comprising a positive electrode as in the previous embodiments.
The invention has the following beneficial effects:
the anode material provided by the invention is embedded into the sodium iron sulfate particles and distributed on the surfaces of the sodium iron sulfate particles by a three-dimensional conductive network structure formed by AZO nano particles so as to improve the conductivity, capacity and rate capability of sodium iron sulfate; the AZO cost is low relative to the carbon nano tube, and the cost of the anode material is low; AZO itself is used as oxide, has excellent high voltage stability to electrolyte, so that the anode material can be endowed with good high voltage stability.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, 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 invention 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 is a schematic diagram of a preparation method according to an embodiment of the present invention;
fig. 2 is an SEM image of the positive electrode material prepared in example 1.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention 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.
The following describes the positive electrode material and the preparation method thereof provided by the embodiment of the invention in detail.
The anode material provided by the embodiment of the invention comprises the iron sodium sulfate particles serving as a base material and three-dimensional conductive network structures embedded into the iron sodium sulfate particles and distributed on the surfaces of the iron sodium sulfate particles, wherein the three-dimensional conductive network structures are formed by AZO nano particles.
The mass ratio of the sodium iron sulfate to the AZO in the positive electrode material is 100:0.5-10 (for example, 100:0.5, 100:1, 100:2, 100:3, 100:5, 100:6, 100:8 or 100:10).
AZO is aluminum doped zinc oxide, is taken as oxide, has excellent high-voltage resistance oxide stability to electrolyte, and is suitable for being taken as a sodium ferric sulfate coating layer to improve interface stability. Meanwhile, AZO has good conductivity, which is equivalent to common conductive agents such as Super P; in the embodiment of the invention, the three-dimensional conductive network structure formed by the AZO nano particles is embedded into the ferric sodium sulfate particles and distributed on the surfaces of the ferric sodium sulfate particles to improve the conductivity, capacity and multiplying power of the ferric sodium sulfate, the obtained positive electrode material not only has good conductivity, capacity and multiplying power, but also has better high-voltage stability, and the AZO is cheaper compared with a carbon nano tube, so that the cost of the positive electrode material provided by the embodiment of the invention is lower compared with that of the carbon nano tube embedded ferric sodium sulfate material.
Preferably, to ensure that the positive electrode material has better overall performance, the mass ratio of sodium iron sulfate to AZO in the positive electrode material is 100:2-8 (e.g., 100:2, 100:3, 100:5, 100:6, or 100:8).
As shown in fig. 1, the preparation method of the positive electrode material provided by the embodiment of the invention includes:
uniformly mixing AZO, a polymer dispersing agent with a chain structure and a sodium ferric sulfate precursor solution to prepare a colloid solution;
drying the colloid solution, and sintering at 300-460 deg.c, 320 deg.c, 350 deg.c, 380 deg.c, 400 deg.c, 430 deg.c or 460 deg.c in inert atmosphere.
According to the preparation method provided by the embodiment of the invention, the polymer dispersing agent is used for enabling the AZO and the sodium iron sulfate precursor to be dispersed uniformly, and because the polymer dispersing agent is provided with a chain structure and is used as a template of the three-dimensional conductive network structure, AZO particles are bonded and arranged to form the three-dimensional conductive network structure, and after sintering, the three-dimensional conductive network structure is embedded in the interior and the surface of the sodium iron sulfate crystal particles. The positive electrode material prepared by the preparation method provided by the embodiment of the invention not only has good conductivity, capacity and multiplying power, but also has better high-voltage stability and lower cost.
It should be noted that, in the preparation method provided by the embodiment of the invention, the purpose of sintering is to make the sodium ferric sulfate precursor (ferrous sulfate and sodium sulfate) generate sodium ferric sulfate, and the polymer dispersing agent may be decomposed due to sintering, but in the present case, the substance for increasing conductivity is AZO, so that whether the polymer dispersing agent has no obvious influence on the improvement of conductivity, so that the sintering temperature can be low, the low-temperature sintering polymer dispersing agent is not decomposed or is decomposed little, the sintering temperature can also be high, and the high-temperature sintering polymer dispersing agent is decomposed more or completely.
Specifically, the inert atmosphere is a nitrogen or argon atmosphere.
Preferably, the sintering time is 6 to 24 hours (e.g., 6 hours, 10 hours, 15 hours, 18 hours, 20 hours, or 24 hours) to ensure that the sodium iron sulfate precursor is sufficiently reacted to sodium iron sulfate.
Preferably, the colloidal solution is dried by spray drying. The spray drying can not only realize the drying of the colloidal solution, but also can prepare granules with uniform particle size distribution, and is favorable for subsequent sintering to obtain the anode material with good microstructure.
Preferably, the mode of uniformly mixing AZO, the polymer dispersing agent with a chain structure and the sodium iron sulfate precursor solution comprises the following steps:
AZO, a polymer dispersing agent with a chain structure and a ferric sodium sulfate precursor solution are mixed and then sanded, so that the AZO, the polymer dispersing agent and the ferric sodium sulfate precursor solution are uniformly mixed.
Further, to ensure that the prepared positive electrode material has better performance, the mass ratio of the sodium iron sulfate precursor to AZO and the polymeric dispersant in the sodium iron sulfate precursor solution is 100:0.5-10:0.1-5 (for example, 100:0.5:5, 100:1:5, 100:3:5, 100:5:5, 100:8:5, 100:10:5, 100:0.5:0.1, 100:0.5:0.5, 100:0.5:1, 100:0.5:2, or 100:0.5:4, etc.).
It should be noted that, if the amount of AZO is too large, AZO will agglomerate, and cannot form uniform distribution in sodium iron sulfate; and too much AZO will reduce the content of active material sodium iron sulfate, resulting in a decrease in battery energy density. Too much polymer dispersant can reduce the conductivity of the sodium iron sulfate material, and too much polymer can form a thicker film, so that the ionic conductivity is reduced, and the rate performance of the battery is poor. Preferably, the mass ratio of the sodium iron sulfate precursor to the AZO, polymeric dispersant in the sodium iron sulfate precursor solution is 100:2-8:0.1-1 (e.g. 100:2:0.1, 100:2:0.2, 100:2:0.5, 100:2:0.8, 100:2:1, 100:3:0.1, 100:4:0.1, 100:5:0.1, 100:6:0.1, 100:7:0.1 or 100:8:0.1, etc.).
Further, the sodium iron sulfate precursor solution is a mixed solution of ferrous sulfate and sodium sulfate, and the mass concentration of the sodium iron sulfate precursor solution is 10-50% (e.g. 10%, 20%, 30%, 40% or 50%), wherein the molar ratio of the ferrous sulfate to the sodium sulfate is 1.5-2.5:1 (e.g. 1.5:1, 2:1 or 2.5:1).
Further, the polymer dispersant with a chain structure is at least one selected from polyacrylic acid, sodium polyacrylate, polyacrylamide, sodium carboxymethyl cellulose and polyurethane.
The positive electrode provided by the embodiment of the invention is prepared from raw materials including the positive electrode material provided by the embodiment of the invention or the positive electrode material prepared by the preparation method provided by the embodiment of the invention.
The sodium ion battery provided by the embodiment of the invention comprises the anode provided by the embodiment of the invention.
The features and capabilities of the present invention are described in further detail below in connection with the examples.
Example 1
And (3) dissolving ferrous sulfate and sodium sulfate in water to prepare a sodium ferric sulfate precursor solution, wherein the mass concentration of the sodium ferric sulfate precursor solution is 20%, and the molar ratio of the ferrous sulfate to the sodium sulfate is 1.9:1.
Mixing AZO, a high-molecular dispersing agent (sodium polyacrylate) and a sodium ferric sulfate precursor according to the mass ratio of the AZO to the sum of the high-molecular dispersing agent (sodium polyacrylate), ferrous sulfate and sodium sulfate of 5:0.2:100, and sanding after mixing to ensure that all the components are mutually dispersed uniformly to obtain a colloid solution;
spray drying the colloid solution to obtain granule;
the particle material is sintered for 12 hours at 350 ℃ to form a positive electrode material of a mixed phase of AZO and sodium iron sulfate, an SEM image of particles of the positive electrode material is shown in figure 2, and as can be seen from figure 2, a three-dimensional conductive network formed by AZO nano particles is embedded into the interior of the sodium iron sulfate particles and distributed to the surfaces of the sodium iron sulfate particles.
Example 2
This embodiment is substantially the same as embodiment 1, except that: the mass ratio of the sum of AZO, the high molecular dispersant (sodium polyacrylate), the ferrous sulfate and the sodium sulfate is 0.5:0.2:100.
Example 3
This embodiment is substantially the same as embodiment 1, except that: the mass ratio of the sum of AZO, the high molecular dispersant (sodium polyacrylate), the ferrous sulfate and the sodium sulfate is 5:0.1:100.
Example 4
This embodiment is substantially the same as embodiment 1, except that: the mass ratio of the AZO to the sum of the polymeric dispersant (sodium polyacrylate), the ferrous sulfate and the sodium sulfate is 5:1:100.
Example 5
This embodiment is substantially the same as embodiment 1, except that: the high molecular dispersing agent is sodium hydroxymethyl cellulose.
Example 6
This embodiment is substantially the same as embodiment 1, except that: the high molecular dispersing agent is polyacrylamide.
Example 7
This embodiment is substantially the same as embodiment 1, except that: the high molecular dispersing agent is polyurethane.
Example 8
This embodiment is substantially the same as embodiment 1, except that: the mass ratio of the sum of AZO, the high molecular dispersant (sodium hydroxymethyl cellulose), ferrous sulfate and sodium sulfate is 10:0.2:100.
Example 9
This embodiment is substantially the same as embodiment 1, except that: the mass ratio of the sum of AZO, the high molecular dispersing agent (polyacrylamide), ferrous sulfate and sodium sulfate is 5:5:100.
Comparative example 1
The comparative example provides a preparation method of undoped AZO sodium ferric sulfate, which comprises the following specific steps:
after spray-drying the sodium iron sulfate precursor solution in example 1, the sintering was performed in the same manner and at the same sintering temperature and time as in example 1.
Comparative example 2
This comparative example is substantially the same as example 1, except that: the preparation process is not added with a high molecular dispersing agent.
Experimental example
Conductivity test: 3g of the compacted powder is weighed and put into a die cavity, the die cavity is vibrated to flatten and even the sample, the die is pressurized by 30Mpa, and the conductivity of the pressurized powder is tested by four probes.
Sodium ion full cell performance test:
and taking the AZO doped ferric sodium sulfate prepared in the embodiment as a positive electrode material of the sodium ion battery, and forming the CR2032 button cell with a metal sodium sheet. Wherein, sodium iron sulfate, SP, PVDF according to 9:0.5: homogenizing in NMP at a mass ratio of 0.5, coating on aluminum foil, and drying to obtain a positive plate; then taking a fresh metal sodium sheet as a battery cathode, and adopting a 16um thick PE base film as a diaphragm; the electrolyte was 1.0mol/L NaPF6 in PC:EMC: FEC=4:6:0.5 solution and assembled into a button cell in an argon-filled glove box to test capacity, rate and cycle performance.
Battery capacity test: the assembled battery was charged to 4.3V at 0.1C and discharged to 2.0V at 0.1C.
Testing the multiplying power performance of the battery: the assembled battery was charged to 4.3V at 0.1C and discharged to 2.0V at 2C.
Cycle life test: the assembled battery was charged to 4.3V at 1C and discharged to 2.0V at 1C, and the recording capacity retention was recorded by 100 cycles.
The results are recorded in table 1:
table 1 properties of the cathode materials of each of examples and comparative examples
As can be seen from the above table, the positive electrode material prepared by each embodiment of the invention has better conductivity, and has better capacity, rate capability and high-voltage stability after being prepared into a sodium ion battery. As can be seen from the test results of examples 1 to 9 (the sodium iron sulfate embedded and coated by AZO) and comparative example 1 (the sodium iron sulfate without embedding and coating), the sodium iron sulfate positive electrode material modified by AZO shows higher powder conductivity, and the capacity, the rate capability and the cycle performance obtained by the test after the battery is assembled are more excellent. In comparative example 2, no polymeric dispersant was added, so that AZO in the prepared cathode material was agglomerated in a large amount, and could not be uniformly dispersed to form a three-dimensional conductive network. Comparing example 1 with comparative example 2, the electrochemical performance of example 1 is significantly better, which indicates that the addition of the polymeric dispersant in the preparation process is beneficial to the uniform dispersion of AZO and the formation of a three-dimensional conductive network structure, and is beneficial to the improvement of the electrochemical performance of the prepared anode material; in comparison of examples 8 and 9 with the other examples, example 8 had a decrease in active material content due to the addition of too much AZO, and the overall gram capacity of the material was rather decreased. In example 9, since a large amount of the polymer dispersant was added, the conductivity and the capacity of the material were poor, which means that too much polymer dispersant would decrease the overall conductivity of the material, and the capacity and the rate performance of the material were lowered. The results show that the AZO participating in the preparation of the positive electrode material is not too much, the dosage of the high molecular dispersing agent is not too much, and the best effect cannot be obtained.
In conclusion, the positive electrode material provided by the invention has the advantages that the three-dimensional conductive network structure formed by AZO nano particles is embedded into the sodium iron sulfate particles and distributed on the surfaces of the sodium iron sulfate particles, so that the conductivity, capacity and multiplying power of the sodium iron sulfate are improved; the AZO cost is low relative to the carbon nano tube, and the cost of the anode material is low; AZO itself is used as oxide, has excellent high voltage stability to electrolyte, so that the anode material can be endowed with good high voltage stability.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The positive electrode material is characterized in that particles of the positive electrode material comprise sodium iron sulfate particles serving as a base material and three-dimensional conductive network structures embedded into the sodium iron sulfate particles and distributed on the surfaces of the sodium iron sulfate particles, wherein the three-dimensional conductive network structures are composed of AZO nano particles.
2. The positive electrode material according to claim 1, wherein the mass ratio of sodium iron sulfate to AZO in the positive electrode material is 100 (0.5-10);
preferably, the mass ratio of the sodium iron sulfate to the AZO in the positive electrode material is 100 (2-8).
3. A method for preparing a positive electrode material, comprising:
uniformly mixing AZO, a polymer dispersing agent with a chain structure and a sodium ferric sulfate precursor solution to prepare a colloid solution;
drying the colloid solution, and sintering at 300-460 ℃ under inert atmosphere.
4. A method of preparing according to claim 3, wherein the colloidal solution is dried by spray drying.
5. The method according to claim 3, wherein the method of uniformly mixing AZO, the polymeric dispersant and the sodium iron sulfate precursor solution comprises:
and mixing AZO, the high molecular dispersing agent and the ferric sodium sulfate precursor solution, and then sanding.
6. The preparation method of claim 3, wherein the mass ratio of the sodium iron sulfate precursor in the sodium iron sulfate precursor solution to the AZO and the high molecular dispersant is 100 (0.5-10): 0.1-5);
preferably, the mass ratio of the sodium iron sulfate precursor in the sodium iron sulfate precursor solution to the AZO and the high molecular dispersing agent is 100 (2-8) (0.1-1).
7. The preparation method according to claim 3, wherein the sodium iron sulfate precursor solution is a mixed solution of ferrous sulfate and sodium sulfate, the mass concentration of the sodium iron sulfate precursor solution is 10-50%, and the molar ratio of the ferrous sulfate to the sodium sulfate is 1.5-2.5:1.
8. The method according to claim 3, wherein the polymer dispersant having a chain structure is at least one selected from the group consisting of polyacrylic acid, sodium polyacrylate, polyacrylamide, sodium carboxymethyl cellulose and polyurethane.
9. A positive electrode, characterized in that it is produced from a raw material comprising the positive electrode material according to claim 1 or 2 or the positive electrode material produced by the production method according to any one of claims 3 to 8.
10. A sodium ion battery comprising the positive electrode of claim 9.
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| CN117790763A (en) * | 2024-02-28 | 2024-03-29 | 江苏众钠能源科技有限公司 | Composite positive electrode material, preparation method thereof, positive electrode plate, secondary battery and application |
| CN117790763B (en) * | 2024-02-28 | 2024-05-14 | 江苏众钠能源科技有限公司 | Composite positive electrode material, preparation method thereof, positive electrode plate, secondary battery and application |
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| CN117790763A (en) * | 2024-02-28 | 2024-03-29 | 江苏众钠能源科技有限公司 | Composite positive electrode material, preparation method thereof, positive electrode plate, secondary battery and application |
| CN117790763B (en) * | 2024-02-28 | 2024-05-14 | 江苏众钠能源科技有限公司 | Composite positive electrode material, preparation method thereof, positive electrode plate, secondary battery and application |
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