CN114220946A - Sodium metavanadate negative pole piece, preparation method thereof and sodium-ion battery - Google Patents

Sodium metavanadate negative pole piece, preparation method thereof and sodium-ion battery Download PDF

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CN114220946A
CN114220946A CN202111514104.0A CN202111514104A CN114220946A CN 114220946 A CN114220946 A CN 114220946A CN 202111514104 A CN202111514104 A CN 202111514104A CN 114220946 A CN114220946 A CN 114220946A
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pole piece
sodium
preparation
sodium metavanadate
negative pole
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严丹林
曹更玉
黄英博
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Guangdong University of Petrochemical Technology
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Guangdong University of Petrochemical Technology
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1397—Processes of manufacture of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy

Abstract

The invention discloses a sodium metavanadate negative pole piece, a preparation method thereof and a sodium ion battery, wherein the preparation method comprises the following steps: s1, adhesive gel preparation: dispersing binder powder with a coating effect in a solvent, and uniformly stirring to prepare a binder gel; s2, preparing anode slurry: dispersing sodium metavanadate powder and a conductive agent in the binder gel obtained in the step S1, adding a proper amount of solvent for dilution, and preparing into negative electrode slurry; s3, coating and preparing a pole piece: and (5) coating the slurry prepared in the step (S2) on a negative current collector, drying by blowing, and then drying in vacuum to obtain the negative pole piece. The preparation method of the sodium metavanadate negative pole piece has the characteristics of good chemical property, low production cost and wide application prospect.

Description

Sodium metavanadate negative pole piece, preparation method thereof and sodium-ion battery
Technical Field
The invention relates to the technical field of sodium ion batteries, in particular to a sodium metavanadate negative electrode plate, a preparation method thereof and a sodium ion battery.
Background
Currently, the depletion of fossil energy and environmental pollution have prompted the exploration of renewable energy sources. The instability of renewable energy sources is characterized by the necessity of energy storage technology. The lithium ion secondary battery is an advanced energy storage technology in the prior art, has the advantages of high working voltage, high energy density, long cycle life, high charge-discharge rate, safety, environmental protection and the like, and is widely applied to consumer electronics and electric vehicles. However, the limited lithium resources in the crust (abundance is 0.0065%), and the distribution is greatly unbalanced in various countries around the world, and the rapid development of new energy industries around the world promotes the further increase of the cost of lithium resources, which all promote people to find the alternative technology of lithium ion batteries. Sodium ion batteries are undoubtedly the most attractive of the many alternative technologies. The two mechanisms are similar, and compared with a lithium resource, the sodium resource is rich (the abundance is 2.74%) and the cost is low.
The search for positive and negative electrode materials with high specific capacity is one of the important challenges in the development of sodium ion batteries. Sodium ion batteries react on a similar principle to lithium ions, and the main difference between the two systems is that the ions participating in the electrochemical reaction are different. Many lithium ion battery electrode materials with excellent performance are researched as sodium ion battery electrode materials, such as layered oxide cathode materials. However, due to the large size difference between lithium ions (0.76 a) and sodium ions (1.03 a), the electrode materials of many lithium ion batteries are not suitable for use in sodium ion battery systems, particularly negative electrode materials. For example, graphite, which is excellent in performance in lithium ion battery systems, is currently the mainstream negative electrode material for commercial lithium ion batteries. Graphite is not suitable for use in sodium ion battery systems because its interlayer spacing is insufficient to accommodate the normal extraction/intercalation of sodium ions. Currently, hard carbon is the most widely studied and commercialized sodium ion battery anode material. The reversible specific capacity of the hard carbon is 100-300mAh/g, and the specific capacity is smaller. Other carbon materials such as graphene oxide, amorphous carbon, petroleum coke, etc. exhibit smaller reversible specific capacity and cannot meet the requirements of practical application. Other types of sodium ion battery negative electrode materials also have a number of problems. E.g. Fe based on conversion reaction mechanism3O4，NiCo2O4，FeS2And Ni3S2The cathode materials have higher reversible capacity (150-400 mAh/g), but the cycle performance is poorer. Sn, Sb, P and other negative electrode materials based on alloy-dealloying reaction also have higher capacity, but the reaction process of the materials is often carried outThere is a comparative volume change resulting in poor cycle performance. The finding of sodium ion battery cathode materials with excellent performance is still a problem to be solved urgently.
Vanadium oxide materials have a high chemical valence, and thus have a possibility of undergoing a multi-electron reaction, and have been widely studied as positive electrode materials for lithium ion batteries, for example, V2O5，LiV3O8，LiVO3And the like. These materials generally have a high capacity, but have a low voltage and are difficult to use in practice. Therefore, vanadium oxide materials have been tried as negative electrode materials for lithium batteries or sodium batteries. Recently, sodium metavanadate NaVO was reported by Liu et al (J. solid. State electrochem. 20 (2016) 1803-1812.)3The initial discharge specific capacity of the lithium ion battery cathode material reaches 623 mAh/g, but the specific capacity is attenuated by 50% after a plurality of cycles. Korean Kim et al in U.S. Pat. No. (US10074850B2) showed alpha-NaVO3The lithium ion battery cathode material has higher specific capacity. Ali et al (ACS appl. Mater. Interfaces 10 (2018) 18717-18725.) and Chandra et al (Electrochimica Acta 331 (2020) 135293.) reported NaVO of monoclinic system3As the electrochemical activity of the negative electrode material of the sodium-ion battery, the first discharge capacity can reach 385 mAh/g, the first coulombic efficiency is low, but the second circulation capacity is obviously attenuated, the circulation stability is poor, and the capacity is attenuated by 45 percent when the negative electrode material is circulated for 100 times at 9 mA/g. The related research of the lithium ion battery system shows that the capacity attenuation problem of the vanadium oxide is closely related to the dissolution of vanadium element in the electrode material in the electrolyte. Fu et al (Phys. chem. Phys. 21 (2019) 7009-7015) slow LiVO by varying the discharge cut-off voltage3The capacity of (2) is attenuated, and the cycle stability is improved. The discharged battery pole pieces are placed in electrode liquid by the battery pole pieces, and the phenomenon of dissolution of vanadium elements with obvious low potential is shown. According to the current report, AVO3A common binder for (a = Li, Na, K) systems is polyvinylidene fluoride (PVDF). Polyvinylidene fluoride is a chain-shaped high polymer material, has good thermal stability and oxidation reduction resistance, the bonding effect is mainly realized through Van der Waals force between the polyvinylidene fluoride and substances, the bonding force is limited in a system with obvious volume expansion, and a pole piece is easy to be bondedAnd (5) powder falling. The polyvinylidene fluoride has low electronic conductivity and ionic conductivity, and the addition of the polyvinylidene fluoride can reduce the electronic conductivity and the ionic conductivity of the whole pole piece and influence the active substance to fully exert the electrochemical performance of the active substance.
Disclosure of Invention
The invention aims to provide a sodium metavanadate negative pole piece, a preparation method thereof and a sodium ion battery, which have the characteristics of good chemical performance, low production cost and wide application prospect.
The invention can be realized by the following technical scheme:
the invention discloses a preparation method of a surface-coated sodium metavanadate negative pole piece, which comprises the following steps:
s1, adhesive gel preparation: dispersing the binder powder with the coating effect in a solvent, and stirring for 15 hours to prepare a binder gel;
s2, preparing anode slurry: dispersing sodium metavanadate powder and a conductive agent in the binder gel obtained in the step S1, adding a proper amount of solvent for dilution, and preparing into negative electrode slurry;
s3, coating and preparing the negative plate: and (5) coating the slurry prepared in the step (S2) on a negative current collector, drying by blowing, and then drying in vacuum to obtain the negative pole piece.
The invention uses the binder with coating effect to react with sodium metavanadate (NaVO) in the preparation process of the electrode3) Surface coating treatment is carried out to prepare sodium metavanadate (NaVO) with excellent electrochemical performance3) And (3) a negative pole piece of the sodium-ion battery. The invention shows that the preparation method of the pole piece utilizes the coating effect of the specific type of adhesive, has the characteristics of simple operation and obvious effect of improving the material performance, and can slow down the dissolution of vanadium element in a low potential state after coating treatment so as to ensure that NaVO3Has practical specific capacity, excellent cycling stability and rate capability.
Further, the active material in S2 includes a phase-pure compound AxVyO3(A = Li, Na, K, Mg, Ca, Ag) and solid solutions thereof.
Further, the active material in S2 comprises 3-20 wt% of carbon-coated pure-phase compound AxVyO3(A = Li, Na, K, Mg, Ca, Ag) and solid solutions thereof.
Further, the binder having a coating effect in S1 includes one or a combination of two or more of polyacrylic acid, lithiated polyacrylic acid, sodium-modified polyacrylic acid, polyacrylate, polybutyl acrylate, polyvinyl alcohol, polyacrylonitrile, and polyvinylidene fluoride in any ratio. When the binder comprises polyvinylidene fluoride, at least another binder is used in combination with the polyvinylidene fluoride.
The coating method can physically separate the active substance from the electrolyte, and is one of the schemes for effectively relieving the dissolution of the active substance. The coated materials are classified into inorganic substances and organic substances, wherein the inorganic substances include oxides, fluorides, phosphides, hydroxides, carbides and the like. For the material with poor electronic conductivity, the coating of the carbide not only has the effect of coating isolation, but also can improve the electronic conductivity of the material. The binder is an important component of the battery, and mainly has the function of binding active substances and current collectors and does not participate in electrochemical reaction. It is to be noted that a part of the binder having a specific functional group functions not only as a binder but also as a coating protection, and has a function similar to that of an artificial solid electrolyte interphase film (SEI film). The hydroxyl in the macromolecular chains is connected with some functional groups on the surface of the active material through hydrogen bonds, and the active material is coated in situ while the adhesive function is achieved, so that the surface energy of the active material can be changed, the activity of surface defects can be reduced, and the dissolving effect of elements can be slowed down.
Further, the binder gel in S1 includes a case where one or more of ammonia water, sodium hydroxide, potassium hydroxide, and lithium hydroxide is added as a pH adjuster or a rheology adjuster for slurry.
Further, the solvent in S1 and S2 is one or more of deionized water, N-methyl pyrrolidone, acetone, acetonitrile, ethanol, methanol, isopropanol, ethylene glycol and glycerol.
Further, the mass fraction of the binder gel in the step S1 is 2-40 wt%.
Further, the mass ratio of the active material to the binder to the conductive agent is: 70-80%, 5-20%, 10-20%.
Further, the vacuum drying temperature range of the pole piece is 90-180 ℃.
Another aspect of the present invention is to provide a method for preparing an electrode of a negative electrode material of a sodium ion battery, where the negative electrode material is the above sodium metavanadate.
Another aspect of the invention is to protect a sodium-ion battery negative plate, and the active material of the negative plate adopts the negative electrode material.
Another aspect of the present invention is to protect a sodium ion battery that employs the above negative electrode sheet.
The sodium metavanadate negative pole piece, the preparation method thereof and the sodium ion battery have the following beneficial effects:
firstly, the electrochemical performance improvement effect is obvious, and the pole piece prepared by the method has higher electronic conductivity and ionic conductivity, so that the active substance shows higher electrochemical activity. The interface reaction of the active substance and the electrolyte can be slowed down, the structural stability of the active material is improved, and the cycle reversibility is further improved;
secondly, the production cost is low, the operation is simple, and the low-price binder with the coating effect is used in the preparation process of the pole piece, so that the production cost is reduced;
and thirdly, the application prospect is good, the materials and the operation flow for preparing the pole piece are common materials and conventional production flows, and the industrialization is easy to realize.
Drawings
In FIG. 1, curves (a) and (b) are X-ray diffraction patterns of active materials used in application example 1 and application example 2, respectively;
FIG. 2 is a scanning electron micrograph of an active material used in application example 1 and application example 2;
fig. 3 is a first charge-discharge curve of application example 1, with polyvinylidene fluoride (PVDF) as the binder. Wherein: the charging and discharging current is 10mA/g, and the charging and discharging voltage range is 0.01-3V;
fig. 4 is a first and second charge-discharge curves of application example 1, in which: the charging and discharging current is 10mA/g, and the charging and discharging voltage range is 0.01-3V;
FIG. 5 is a graph of rate performance for application example 1, wherein: the charging and discharging currents are respectively 20 mA/g, 40 mA/g, 100 mA/g, 200 mA/g and 400 mA/g, and the charging and discharging voltage range is 0.01-3V;
FIG. 6 is a cycle performance curve of application example 1, in which: the charging and discharging current is 300mA/g, and the charging and discharging voltage range is 0.01-3V;
FIG. 7 is a first and second charging/discharging curves of application example 2, in which the charging/discharging current is 10mA/g and the charging/discharging voltage range is 0.01-3V.
FIG. 8 is a graph of rate performance for application example 2, wherein: the charging and discharging currents are respectively 20 mA/g, 40 mA/g, 100 mA/g, 200 mA/g and 400 mA/g, and the charging and discharging voltage range is 0.01-3V;
FIG. 9 is a cycle performance curve of application example 2, in which: the charging and discharging current is 300mA/g, and the charging and discharging voltage range is 0.01-3V;
FIG. 10 is a first and second charging/discharging curves of application example 3, in which the charging/discharging current is 10mA/g and the charging/discharging voltage range is 0.01-3V.
FIG. 11 is a graph of rate performance for application example 2, wherein: the charging and discharging currents are respectively 20 mA/g, 40 mA/g, 100 mA/g, 200 mA/g and 400 mA/g, and the charging and discharging voltage range is 0.01-3V.
Detailed Description
In order to make the technical solutions of the present invention better understood by those skilled in the art, the following detailed description of the present invention is provided with reference to the accompanying drawings.
The invention discloses a preparation method of a surface-coated sodium metavanadate negative pole piece, which comprises the following steps:
s1, adhesive gel preparation: dispersing binder powder with a coating effect in a solvent, and uniformly stirring to prepare a binder gel;
s2, preparing anode slurry: dispersing sodium metavanadate powder and a conductive agent in the binder gel obtained in the step S1, adding a proper amount of solvent for dilution, and preparing into negative electrode slurry;
s3, coating and preparing the negative plate: and (5) coating the slurry prepared in the step (S2) on a negative current collector, drying by blowing, and then drying in vacuum to obtain the negative pole piece.
Further, the active material in S2 includes a phase-pure compound AxVyO3(A = Li, Na, K, Mg, Ca, Ag) and solid solutions thereof.
Further, the active material in S2 comprises 3-20 wt% of carbon-coated pure-phase compound AxVyO3(A = Li, Na, K, Mg, Ca, Ag) and solid solutions thereof.
Further, the binder having a coating effect in S1 includes one or a combination of two or more of polyacrylic acid, lithiated polyacrylic acid, sodium-modified polyacrylic acid, polyacrylate, polybutyl acrylate, polyvinyl alcohol, polyacrylonitrile, and polyvinylidene fluoride in any ratio. When the binder comprises polyvinylidene fluoride, at least another binder is used in combination with the polyvinylidene fluoride.
Further, the binder gel in S1 includes a case where one or more of ammonia, sodium hydroxide, potassium hydroxide, and lithium hydroxide is added as a PH adjuster or a rheology adjuster for slurry.
Further, the solvent in S1 and S2 is one or more of deionized water, N-methyl pyrrolidone, acetone, acetonitrile, ethanol, methanol, isopropanol, ethylene glycol and glycerol.
Further, the mass fraction of the binder gel in the step S1 is 2-40 wt%.
Further, the mass ratio of the active material to the binder to the conductive agent is: 70-80%, 5-20%, 10-20%.
Further, the vacuum drying temperature range of the pole piece is 90-180 ℃.
In the present invention, a part of the binder having a specific functional group not only functions as a binder but also functions as a coating protection, having a function similar to that of an artificial solid electrolyte interphase (SEI film). The hydroxyl in the macromolecular chains is connected with some functional groups on the surface of the active material through hydrogen bonds, and the active material is coated in situ while the adhesive function is achieved, so that the surface energy of the active material can be changed, the activity of surface defects can be reduced, and the dissolving effect of elements can be slowed down.
Another aspect of the present invention is to provide a method for preparing an electrode of a negative electrode material of a sodium ion battery, where the negative electrode material is the above sodium metavanadate.
Another aspect of the invention is to protect a sodium-ion battery negative plate, and the active material of the negative plate adopts the negative electrode material.
Another aspect of the present invention is to protect a sodium ion battery that employs the above negative electrode sheet.
Application example 1
The active substance sodium metavanadate (. beta. -NaVO)3) The X-ray diffraction diagram is shown as a curve in figure 1, and the figure shows that the active substance is pure phase orthorhombic sodium metavanadate (. beta. -NaVO)3) And (3) a negative electrode material. The morphology of the active substance is shown in fig. 2a, which is an irregular strip-shaped particle morphology.
The preparation process comprises the following steps: polyacrylic acid was first dispersed in NMP organic solvent to prepare a 10% wt polyacrylic acid/NMP gel. Then, sodium metavanadate (0.6000g) and acetylene black (0.0750g) were ground and mixed in a mass ratio of 8:1, and the resulting mixture was dispersed in the obtained polyacrylic acid/NMP gel (0.7500g), diluted with NMP solvent, and magnetically stirred at 25 ℃ for 4 hours to prepare a negative electrode slurry. Coating the prepared slurry on an aluminum foil, drying by blowing at 60 ℃, and drying in vacuum at 110 ℃ for 24 hours to finally prepare the negative pole piece of the sodium-ion battery. As a comparison, sodium metavanadate, acetylene black and polyvinylidene fluoride (PVDF) with the same mass are used as raw materials, NMP is used as a solvent, and the slurry is prepared by the same steps, and finally the pole piece is prepared.
The electrochemical performance test process comprises the following steps: the first charge-discharge curve of the electrode of PVDF under the voltage range of 0.01-3V and the current density of 10mA/g is shown in figure 3. The first discharge specific capacity is 350 mAh/g, the charge specific capacity is 56 mAh/g, and the first discharge specific capacity isCoulomb efficiency is very low. The first charge-discharge and second discharge curves of the polyacrylic acid-coated material are shown in fig. 4, the rate performance is shown in fig. 5, and the cycle performance is shown in fig. 6. It can be seen that the first discharge and charge capacities at a current density of 10mA/g are 176 mAh/g and 360mAh/g, the second discharge capacity is 204 mAh/g, and the discharge plateau is about 0.5V (vs. Na/Na)+). From the circulation curve of FIG. 6, under the current of 300mA/g, the first capacity is 50mAh/g, the specific discharge capacity after 100 cycles is 39 mAh/g, and the capacity retention rate is 78%. From the rate performance graph of FIG. 5, it can be seen that when the current density is 200 mA/g and 400 mA/g, the specific discharge capacity can still reach 70mAh/g and 42 mAh/g. It can be seen that the negative electrode material has a large capacity loss after the first discharge, which can be attributed to the formation of SEI film during the first discharge, consuming a part of Na+Causing irreversible loss of capacity. However, in spite of this, sodium metavanadate (. beta. -NaVO) coated with polyacrylic acid3) The electrochemical performance of the cathode material at low rate is obviously improved, and the cathode material already shows practical capacity which can be compared with the hard carbon (100-300 mAh/g) of the cathode material of the current commercial sodium battery.
Application example 2
Carbon-coated sodium metavanadate (. beta. -NaVO)3) The X-ray diffraction pattern of the active substance is shown as b curve in figure 1, and it can be known that all the active substances are orthorhombic carbon-coated sodium metavanadate (. beta. -NaVO)3) And (3) a negative electrode material. The scanning electron microscope picture of the active substance is shown in figure 2b, the active substance is in a strip shape, and the graphene is uniformly coated with sodium vanadate (beta-NaVO)3) And (3) a negative electrode material.
The preparation process comprises the following steps: polyacrylic acid was first dispersed in NMP organic solvent to prepare a 10% wt polyacrylic acid/NMP gel. Grinding and mixing carbon-coated sodium metavanadate (0.6000g) and acetylene black (0.0750g) according to a mass ratio of 8:1, dispersing the mixture in the prepared polyacrylic acid/NMP gel (0.7500g), adding an NMP solvent for dilution, and magnetically stirring at 25 ℃ for 4 hours to prepare negative electrode slurry. Coating the prepared slurry on an aluminum foil, drying by blowing at 60 ℃, and drying in vacuum at 110 ℃ for 24 hours to finally prepare the negative pole piece of the sodium-ion battery. The carbon coating is partially coated withSodium vanadate (. beta. -NaVO)3) The first charge-discharge and second discharge curves of the negative electrode material with a current density of 10mA/g in a voltage range of 0.01-3V and a voltage range of 0.01-3V are shown in FIG. 7, the rate performance is shown in FIG. 8, and the cycle performance is shown in FIG. 9. The first discharge capacity is 450 mAh/g and 203 mAh/g under 10mA/g, the second discharge capacity is 250mAh/g, and the discharge platform is about 0.5V. From the cycle curve of FIG. 8, the first capacity was 76 mAh/g at a current of 300mA/g, the specific discharge capacity after 100 cycles was 68 mAh/g, and the capacity retention rate was 89%. Compared with the sodium metavanadate anode material without carbon coating in application example 1, the material coated with carbon has the advantages that the electrode plate preparation method greatly improves the charge-discharge capacity and the cycle performance, so that the sodium metavanadate (beta-NaVO)3) The cathode material is more competitive in the cathode material of the sodium-ion battery.
Application example 3
The active substance sodium metavanadate (. beta. -NaVO)3) The X-ray diffraction diagram is shown as a curve in figure 1, and the figure shows that the active substance is pure phase orthorhombic sodium metavanadate (. beta. -NaVO)3) And (3) a negative electrode material.
The preparation process comprises the following steps: a 10% wt binder gel was prepared by first dispersing partially lithiated (25%) polyacrylic acid in NMP organic solvent. Then, sodium metavanadate (0.6000g) and acetylene black (0.0750g) were ground and mixed in a mass ratio of 8:1, and the resulting mixture was dispersed in the prepared binder gel (0.7500g), diluted with NMP solvent, and magnetically stirred at 25 ℃ for 4 hours to prepare a negative electrode slurry. Coating the prepared slurry on an aluminum foil, drying by blowing at 60 ℃, and drying in vacuum at 100 ℃ for 24 hours to finally prepare the negative pole piece of the sodium-ion battery.
The electrochemical performance test process comprises the following steps: the first charge-discharge and second discharge curves of current density of 10mA/g in the voltage range of 0.01-3V are shown in FIG. 10, and the rate capability is shown in FIG. 11. The first discharge capacity is 376 mAh/g and 157 mAh/g under 10mA/g, and the second discharge capacity is 249 mAh/g. From the rate performance curve of FIG. 10, it can be seen that when the current density is 200 mA/g and 400 mA/g, the specific discharge capacity can still reach 76 mAh/g and 52 mAh/g. Compared with the application example 1, the discharge specific capacity of the material under high current density is improved by using the partially lithiated polypropylene.
From the above examples, it can be seen that the surface-coated sodium metavanadate anode material prepared by the preparation method of the present invention. In the embodiment, after polyacrylic acid coating, carbon coating and partial lithiation polypropylene coating are carried out on the sodium metavanadate negative electrode material, the surface coating can slow down the dissolution of the V element in the low-potential discharge process, and the electrochemical performance of the material is obviously improved compared with that of an uncoated sample, especially the cycling stability. Therefore, the sodium metavanadate anode material after surface coating has higher reversible specific capacity than that of the uncoated sodium metavanadate anode material.
The above embodiments are only specific embodiments of the present invention, and the description thereof is specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications are possible without departing from the inventive concept, and such obvious alternatives fall within the scope of the invention.

Claims (9)

1. A preparation method of a sodium metavanadate negative pole piece is characterized by comprising the following steps:
s1, adhesive gel preparation: dispersing binder powder with a coating effect in a solvent, and uniformly stirring to prepare a binder gel;
s2, preparing anode slurry: dispersing sodium metavanadate powder and a conductive agent in the binder gel obtained in the step S1, adding a proper amount of solvent for dilution, and preparing into negative electrode slurry;
s3, coating and preparing a pole piece: and (5) coating the slurry prepared in the step (S2) on a negative current collector, drying by blowing, and then drying in vacuum to obtain the negative pole piece.
2. The method for preparing the sodium metavanadate negative pole piece according to claim 1, which is characterized in that: the active material in step S2 includes the phase-pure compound AxVyO3And a solid solution thereof,wherein A is Li, Na, K, Mg, Ca, Ag.
3. The preparation method of the sodium metavanadate negative pole piece according to claim 2, characterized by comprising the following steps: the active material in step S2 includes the case of applying 3-20 wt% carbon coating treatment to the material in claim 2.
4. The preparation method of the sodium metavanadate negative pole piece according to claim 3, characterized by comprising the following steps: in step S1, the binder having a coating effect is one or a combination of two or more of polyacrylic acid, lithiated polyacrylic acid, sodium-modified polyacrylic acid, polyacrylate, polybutyl acrylate, polyvinyl alcohol, polyacrylonitrile, and polyvinylidene fluoride.
5. The preparation method of the sodium metavanadate negative pole piece according to claim 4, characterized by comprising the following steps: in step S1, the binder gel includes one or more of ammonia, sodium hydroxide, potassium hydroxide, and/or lithium hydroxide as a pH adjuster.
6. The preparation method of the sodium metavanadate negative pole piece according to claim 5, which is characterized in that: in steps S1 and S2, the solvent is one or a mixture of two or more of deionized water, N-methylpyrrolidone, acetone, acetonitrile, ethanol, methanol, isopropanol, ethylene glycol, and glycerol.
7. The preparation method of the sodium metavanadate negative pole piece according to claim 6, which is characterized in that: the mass fraction of the adhesive gel is 2-40 wt%; the mass ratio of the active substance to the binder to the conductive agent is 70-80%, 5-20%, 10-20%; the vacuum drying temperature range of the pole piece is 90-180 ℃.
8. The negative electrode plate is prepared by the preparation method of the sodium metavanadate negative electrode plate according to any one of claims 1 to 7.
9. A sodium ion battery, which adopts the sodium metavanadate negative electrode plate of claim 8.
CN202111514104.0A 2021-12-13 2021-12-13 Sodium metavanadate negative pole piece, preparation method thereof and sodium-ion battery Pending CN114220946A (en)

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Citations (4)

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