CN115513452A - Polyanion type sodium ion battery positive electrode material and preparation method thereof - Google Patents

Polyanion type sodium ion battery positive electrode material and preparation method thereof Download PDF

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CN115513452A
CN115513452A CN202211133667.XA CN202211133667A CN115513452A CN 115513452 A CN115513452 A CN 115513452A CN 202211133667 A CN202211133667 A CN 202211133667A CN 115513452 A CN115513452 A CN 115513452A
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sodium
water
soluble
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ion battery
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李郎阁
赵阿龙
曹余良
范海满
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Shenzhen Jana Energy Technology Co ltd
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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
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
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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
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
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Abstract

The invention discloses a polyanionic sodium-ion battery anode material and a preparation method thereof, wherein the general formula of the polyanionic sodium-ion battery anode material is Na 4 M x P 4 O 12+x Wherein, the value range of x is more than or equal to 2.0 and less than or equal to 4.0, M is one or two of Fe, co, ni, cu, zn and Mn; by controlling the change of the x value, the polyanionic sodium-ion battery anode material is single-phase or two-phase. The polyanionic sodium-ion battery anode material has the characteristics of strong theoretical guidance, low production cost and high product purity.

Description

Polyanion type sodium ion battery positive electrode material and preparation method thereof
Technical Field
The invention relates to the technical field of sodium ion batteries, in particular to a polyanion type sodium ion battery positive electrode material and a preparation method thereof.
Background
With the use of fossil energy in large quantities, environmental pollution is becoming a prominent issue since the industrial revolution. To solve this problem, a series of environmental protection measures have been developed in succession in each country. Among them, new forms of energy electric automobile replace fuel oil vehicle is an effective way. The popularization of new energy electric vehicles is far from the development of secondary batteries, and the secondary batteries become an ideal choice for the current vehicle-mounted power system due to the advantages of no environmental pollution, mature technology, convenience in operation, high energy conversion rate and the like. The secondary batteries are abundant in variety, and have different grades according to different marketization requirements, such as lead-acid batteries for small electric vehicles, lithium ion batteries for 3C electronic products, sodium ion batteries for large-scale energy storage, and nickel-hydrogen batteries, nickel-cadmium batteries, alkaline zinc-manganese batteries for other purposes, and the like, but lithium/sodium ion batteries are clearly outstanding in the future new energy field in terms of technical reliability, large-scale application cost, energy conversion efficiency, and environmental suitability.
In recent years, the wide popularization of new energy automobiles drives the rapid development of lithium ion batteries. However, the lithium resource reserves in the world are deficient and the regional distribution is uneven, so that the demands in the field of electric vehicles cannot be met, the cheap requirement of large-scale energy storage cannot be met, the price of lithium carbonate is increased dramatically, and the manufacturing cost of the lithium ion battery is increased.
The sodium ion battery has a working principle similar to that of the lithium ion battery, and is rich in sodium resource reserves and low in mining cost. Under the same condition, the manufacturing cost of the sodium ion battery electrode material is lower, and the sodium ion battery electrode material is expected to be widely applied to the field of energy storage. The sodium ion positive electrode material comprises transition metal oxide, prussian blue and analogues thereof and polyanion materials, and different materials have obvious difference in capacity, multiplying power and structural stability. The current research shows that transition metal oxide is often accompanied with a plurality of phase changes in the process of redox sodium ion desorption, thereby causing the collapse of the structure and further influencing the cycle stability of the material. The crystal structure of the Prussian blue and the like contains a large amount of crystal water, and the crystal water is easy to decompose at a high potential to generate gas, so that the battery is swelled and loses efficacy. Compared with the first two types of materials, the polyanion type positive electrode material of the sodium-ion battery is undoubtedly the best choice of the positive electrode of the sodium-ion battery due to the stable framework structure and the excellent electrochemical performance of the polyanion type positive electrode material.
Currently, many studies have been made on polyanionic sodium ion batteriesThe positive electrode material contains Na 3 V 2 (PO 4 ) 3 ，NaVPO 4 And V-based phosphates such as F. Although the V-based phosphate has higher oxidation-reduction potential (3.4-3.6V) and specific capacity, the V-based resource has limited reserve capacity and stronger toxicity, so that the V-based material is difficult to realize large-scale application. However, the non-V system metal-based phosphate is non-toxic, pollution-free and cheap, and lays a good foundation for large-scale application of the metal-based phosphate.
At present, the preparation processes of the polyanionic sodium-ion battery positive electrode material metal-based phosphate are divided into two types: firstly, a solid phase ball milling process is adopted, metal salt, sodium salt, a phosphorus source, a carbon source (glucose, citric acid, sucrose and the like) and the like which are insoluble in water are mixed and ball milled, then precursor powder is obtained through spray drying, and a final product is obtained after calcination. However, the solid phase ball milling process does not guarantee Na, M and PO 4 The uniform mixing between the two components results in a large amount of mixed phases generated in the final product, and the electrochemical performance of the material is influenced. Secondly, adopting a liquid phase process to mix and dissolve metal salts which are easy to dissolve in water, sodium salts (sodium carbonate, sodium hydroxide, sodium oxalate, sodium phosphate and the like), phosphorus sources (sodium pyrophosphate, ammonium dihydrogen phosphate, sodium phosphate, monohydrogen phosphate/sodium dihydrogen phosphate and the like) and carbon sources (glucose, citric acid, sucrose and the like), and the like, spray-drying to obtain precursor powder, and calcining to obtain the final product. However, the water-soluble metal salts are very easy to absorb water and the melting point of the carbon source such as glucose, citric acid, sucrose and the like is low, the viscosity is high, so that the powder is seriously adhered to the wall in the spray drying process and cannot be normally collected. In addition, the phosphate metal salt has low solubility product and is extremely difficult to dissolve in water, and the liquid phase mixing process is often accompanied with the generation of phosphate precipitates, which cause Na, M and PO 4 Resulting in a large amount of heterogeneous phase in the final product.
Disclosure of Invention
The invention aims to provide a polyanion type sodium ion battery anode material which has the characteristics of strong theoretical guidance, low production cost and high product purity.
The invention can be realized by the following technical scheme:
the invention discloses a polyanionic sodium-ion battery anode material, and the general formula of the polyanionic sodium-ion battery anode material is Na 4 M x P 4 O 12+x Wherein, the value range of x is more than or equal to 2.0 and less than or equal to 4.0, M is one or more than two of Fe, co, ni, cu, zn and Mn; by controlling the change of the x value, the polyanionic sodium-ion battery anode material is single-phase or two-phase.
Further, when x =2.0, the polyanionic sodium-ion battery positive electrode material is Na 4 M 2 P 4 O 14 The structure of which belongs to a triclinic system P-1/monoclinic system P2 1 One of the/c space groups. Cell parameter of
Figure BDA0003851005930000021
Figure BDA0003851005930000022
61.2≦α°≦65.6、81.3≦β°≦87.9、71.2≦γ°≦75.8、
Figure BDA0003851005930000023
Further, when 2.9<x<At 2.97, the polyanionic sodium-ion battery positive electrode material is Na 4 M x P 4 O 12+x The structure belongs to the orthorhombic Pn21a space group. Cell parameters of
Figure BDA0003851005930000024
Figure BDA0003851005930000025
Further, when x =4.0, the polyanionic sodium-ion battery positive electrode material is Na 4 M 4 P 4 O 16 The structure belongs to the orthorhombic Pnma space group. Cell parameters of
Figure BDA0003851005930000026
Figure BDA0003851005930000027
Further, when 2.0<When x is less than or equal to 2.9, the polyanion type sodium-ion battery anode material is Na 4 M x P 4 O 12+x The structure is triclinic P-1/monoclinic P2 1 A two-phase mixture of/c and the space group of orthorhombic Pn21 a.
Further, when x is 2.97 ≦ x<At 4.0, the polyanionic sodium-ion battery positive electrode material is Na 4 M x P 4 O 12+x The structure is a two-phase mixture of the orthorhombic Pn21a and orthorhombic Pnma space groups.
Another aspect of the present invention is a method for protecting a positive electrode material of the polyanionic sodium-ion battery, including the steps of:
s1, weighing the following raw materials: according to the different values of x, according to the general formula of the material Na 4 M x P 4 O 12+x Weighing a dispersing agent, a water-soluble sodium source, a water-soluble metal source, a water-soluble phosphorus source and a water-soluble carbon source according to the stoichiometric ratio;
s2, adjusting the pH value of the solution: : adjusting the pH value of water to 1-4 by using citric acid, adding a water-soluble metal source to form a citric acid-metal complex, and further avoiding uneven ion distribution caused by the generation of metal phosphate precipitates when a subsequent phosphorus source is introduced;
s3, preparing a precursor solution: adding a dispersing agent, a sodium source, a phosphorus source and a water-soluble carbon source into the solution obtained in the step S2 to form a precursor solution;
s4, spray drying: spray drying the precursor solution in the step S3 to obtain dry precursor powder;
s5, sintering of precursor powder: and (4) sintering the precursor powder in the step (S4) at high temperature to obtain the polyanionic sodium-electrode anode material.
Further, in the precursor solution obtained in step S3, the solid content of the solution is 10 to 50wt%, the dispersant accounts for 1 to 15wt% of the total solid content of the solution, and the water-soluble carbon source accounts for 1 to 10wt% of the total solid content of the solution.
Further, in the sintering of the precursor powder in step S5, the sintering conditions are: the sintering temperature interval is 450-650 ℃, and the sintering time is 5-15H.
Further, the dispersant is one or more of polyvinyl alcohol, polyethylene glycol, polypropylene glycol, polyethylene oxide, polytetrafluoroethylene, polyacrylic acid, polymethyl acrylate, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, carboxyethyl cellulose, carboxypropyl methyl cellulose and carboxyethyl methyl cellulose;
preferably, wherein the water-soluble sodium source is one or more of sodium formate, sodium acetate, sodium sulfate, sodium nitrate, sodium citrate, sodium phosphate, mono/di sodium phosphate and sodium chloride;
preferably wherein the water soluble source of phosphorus is one or more of phosphoric acid, ammonium dihydrogen phosphate, sodium monohydrogen/dihydrogen phosphate, and sodium phosphate;
preferably, the water-soluble carbon source is citric acid, glucose, sucrose, maltose, lactose, cyclodextrin and water-soluble starch.
Further, the water-soluble metal source is a water-soluble iron source, a water-soluble cobalt source, a water-soluble nickel source, a water-soluble zinc source, a water-soluble manganese source and/or a water-soluble copper source;
wherein the water-soluble iron source is one or more of ferric sulfate/ferrous iron, ferric formate, ferric acetate, ferric nitrate and ferrous ammonium sulfate.
Wherein the water-soluble cobalt source is one or more of cobalt sulfate, cobalt acetate, cobalt nitrate and cobalt chloride.
Wherein the water-soluble nickel source is one or more of nickel sulfate, nickel chloride and nickel nitrate.
Wherein the water soluble zinc source is one or more of zinc sulfate, zinc acetate, zinc chloride, zinc nitrate and zinc gluconate.
Wherein the water-soluble manganese source is one or more of manganese acetate, manganese sulfate, manganese nitrate and manganese chloride.
Wherein the water-soluble copper source is one or more of copper nitrate, copper sulfate, copper chloride, copper acetate and copper perchlorate. The polyanion type sodium ion battery positive electrode material and the preparation method thereof have the following beneficial effects:
(1) The phase composition of the metal-based polyanionic sodium-ion battery anode material with the general formula of Na4MxP4O12+ x is analyzed, theoretical support is formed for large-scale production, and the production operation control is facilitated.
(2) The mass preparation of the metal-based polyanionic sodium-ion battery anode material is realized by adopting a cheap water-soluble metal source, and the production cost of the material is effectively reduced.
(3) The acidity, complexation and high-temperature pyrolysis carbon-forming property of citric acid are utilized to reduce the activity of metal ions in the solution, so that the generation of phosphate metal salt precipitation during the preparation of the solution is avoided, and the phase purity of the material is effectively ensured.
(4) The compactness of carbon formed by the pyrolysis of glucose/sucrose/soluble starch is utilized to further compensate the nonuniformity of the citric acid in the surface pyrolysis of the material, so that the electronic conductivity of the material is greatly improved.
(5) The hygroscopicity and viscosity of citric acid, glucose and the like are reduced by utilizing the high melting point, low viscosity, low hygroscopicity and high dispersion property of the dispersing agent, so that the fluidity of the material is improved, and the normal material collection in the spray drying process is ensured.
Drawings
FIG. 1 shows Na in application example 1 4 Fe 2.93 P 4 O 14.93 SEM pictures of the material;
FIG. 2 shows Na in application example 1 4 Fe 2.93 P 4 O 14.93 XRD pattern of the material;
FIG. 3 shows Na in application example 1 4 Fe 2.93 P 4 O 14.93 First cycle charge and discharge curve chart of the material;
FIG. 4 shows Na in application example 1 4 Fe 2.93 P 4 O 14.93 A cyclical stability profile of the material;
FIG. 5 is Na of comparative example 1 4 Fe 2.93 P 4 O 14.93 XRD pattern of the material;
FIG. 6 shows Na in comparative example 1 4 Fe 2.93 P 4 O 14.93 First week of MaterialA charge-discharge curve chart;
FIG. 7 shows Na in comparative example 1 4 Fe 2.93 P 4 O 14.93 A cyclical stability profile of the material;
FIG. 8 shows Na in comparative example 2 4 Fe 2 P 4 O 14 SEM image of material.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the following detailed description will be made with reference to the embodiments and the accompanying drawings.
The invention discloses a polyanionic sodium-ion battery anode material, and the general formula of the polyanionic sodium-ion battery anode material is Na 4 M x P 4 O 12+x Wherein, the value range of x is more than or equal to 2.0 and less than or equal to 4.0, M is one or more than two of Fe, co, ni and Cu; by controlling the change of the x value, the polyanionic sodium-ion battery anode material is in a single phase or two phases.
Further, when x =2.0, the polyanionic sodium-ion battery positive electrode material is Na 4 M 2 P 4 O 14 The structure of which belongs to a triclinic system P-1/monoclinic system P2 1 One of the/c space groups. Cell parameter of
Figure BDA0003851005930000051
Figure BDA0003851005930000052
61.2≦α°≦65.6、81.3≦β°≦87.9、71.2≦γ°≦75.8、
Figure BDA0003851005930000053
Further, when 2.9<x<At 2.97, the polyanionic sodium-ion battery positive electrode material is Na 4 M x P 4 O 12+x The structure belongs to the orthorhombic Pn21a space group. Cell parameters of
Figure BDA0003851005930000054
Figure BDA0003851005930000055
Further, when x =4.0, the polyanionic sodium-ion battery positive electrode material is Na 4 M 4 P 4 O 16 The structure belongs to the orthorhombic Pnma space group. Cell parameters of
Figure BDA0003851005930000056
Figure BDA0003851005930000057
Further, when 2.0<When x is less than or equal to 2.9, the polyanion type sodium-ion battery anode material is Na 4 M x P 4 O 12+x The structure is triclinic P-1/monoclinic P2 1 A two-phase mixture of/c and the space group of orthorhombic Pn21 a.
Further, when x is 2.97 ≦ x<At 4.0, the polyanionic sodium-ion battery positive electrode material is Na 4 M x P 4 O 12+x The structure is a two-phase mixture of the orthorhombic Pn21a and orthorhombic Pnma space groups.
Another aspect of the present invention is a method for protecting a positive electrode material of the polyanionic sodium-ion battery, including the steps of:
s1, weighing the following raw materials: according to the different values of x, according to the general formula of the material Na 4 M x P 4 O 12+x Weighing a dispersing agent, a water-soluble sodium source, a water-soluble metal source, a water-soluble phosphorus source and a water-soluble carbon source according to the stoichiometric ratio;
s2, adjusting the pH value of the solution: : adjusting the pH value of water to 1-4 by using citric acid, adding a water-soluble metal source to form a citric acid-metal complex, and further avoiding uneven ion distribution caused by the generation of metal phosphate precipitates when a subsequent phosphorus source is introduced;
s3, preparing a precursor solution: adding a dispersing agent, a sodium source, a phosphorus source and a water-soluble carbon source into the solution obtained in the step S2 to form a precursor solution;
s4, spray drying: spray drying the precursor solution in the step S3 to obtain dried precursor powder;
s5, sintering of precursor powder: and (4) sintering the precursor powder in the step (S4) at high temperature to obtain the polyanionic sodium-electrode anode material.
Further, in the precursor solution obtained in step S3, the solid content of the solution is 10 to 50wt%, the dispersant accounts for 1 to 15wt% of the total solid content of the solution, and the water-soluble carbon source accounts for 1 to 10wt% of the total solid content of the solution.
Further, in the sintering of the precursor powder in step S5, the sintering conditions are: the sintering temperature range is 450-650 ℃, and the sintering time is 5-15H.
Further, the dispersant is one or more of polyvinyl alcohol, polyethylene glycol, polypropylene glycol, polyethylene oxide, polytetrafluoroethylene, polyacrylic acid, polymethyl acrylate, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, carboxyethyl cellulose, carboxypropyl methyl cellulose and carboxyethyl methyl cellulose;
preferably, wherein the water-soluble sodium source is one or more of sodium formate, sodium acetate, sodium sulfate, sodium nitrate, sodium citrate, sodium phosphate, mono/di sodium phosphate and sodium chloride;
preferably wherein the water soluble source of phosphorus is one or more of phosphoric acid, ammonium dihydrogen phosphate, sodium monohydrogen/dihydrogen phosphate, and sodium phosphate;
preferably, the water-soluble carbon source is citric acid, glucose, sucrose, maltose, lactose, cyclodextrin and water-soluble starch.
Further, the water-soluble metal source is a water-soluble iron source, a water-soluble cobalt source, a water-soluble nickel source, a water-soluble zinc source, a water-soluble manganese source and/or a water-soluble copper source;
wherein the water-soluble iron source is one or more of ferric sulfate/ferrous iron, ferric formate, ferric acetate, ferric nitrate and ferrous ammonium sulfate.
Wherein the water-soluble cobalt source is one or more of cobalt sulfate, cobalt acetate, cobalt nitrate and cobalt chloride.
Wherein the water-soluble nickel source is one or more of nickel sulfate, nickel chloride and nickel nitrate.
Wherein the water soluble zinc source is one or more of zinc sulfate, zinc acetate, zinc chloride, zinc nitrate and zinc gluconate.
Wherein the water-soluble manganese source is one or more of manganese acetate, manganese sulfate, manganese nitrate and manganese chloride.
Wherein the water-soluble copper source is one or more of copper nitrate, copper sulfate, copper chloride, copper acetate and copper perchlorate.
In the technical scheme, the pH value of the solution is regulated and controlled, the generation of phosphate radical metal salt precipitation is prevented, and the problems that the phosphate radical metal salt has small solubility product and is easy to precipitate in an aqueous solution, so that sodium, iron and phosphorus elements are not uniformly distributed in the drying process and the like are effectively solved; the complexing agent is adopted to stabilize metal ions in the solution, so that the generation of phosphate radical metal salt precipitation is prevented, and the advantages of high hydrophilicity and increased hygroscopicity of the material due to the fact that citric acid, glucose, sucrose or soluble starch contains a large amount of hydroxyl and carboxyl groups are fully exerted; by adding the dispersing agent with high dispersibility and high melting point and optimizing the proportion among the dispersing agent, the citric acid, the glucose, the sucrose or the soluble starch, the viscosity and the hygroscopicity of the material are reduced under the condition of ensuring the sufficient amount of the carbon source, the dryness of the powder is ensured, and the problems that the citric acid, the glucose and the sucrose have relatively low melting points, are easy to melt in the spraying process and adhere to the pipe wall of a spray dryer to cause the abnormal collection of the material are solved.
The invention provides a new positive electrode material Na for preparing polyanion sodium-ion batteries 4 M x P 4 O 12+x And (x is more than or equal to 2.0 and less than or equal to 4.0), the process adopts metal salt which is low in cost and easy to dissolve in water, and utilizes the acidity and complexing capacity of citric acid to reduce the activity of metal ions in the solution, so that the metal phosphate precipitation generated in the liquid phase mixing process is avoided. In addition, the hygroscopicity and the viscosity of the powder in the spraying process are regulated and controlled by adding a small amount of dispersing agent with high dispersibility and high melting point into the solution, and then the dry precursor powder is obtained. The process is simple and the raw materials are cheap, and can be used for polyionThe batch production of the positive electrode material of the son-type sodium-ion battery provides reference.
As can be seen from the above description, the metal-based polyanionic sodium-ion battery positive electrode material of the present invention mainly relates to iron-based, cobalt-based, nickel-based, zinc-based, manganese-based, and copper-based. In order to facilitate understanding of the present invention, polyanionic sodium-ion battery positive electrode materials are specifically described below in conjunction with examples 1 to 9, application examples 1 to 3, and comparative examples 1 to 3:
example 1
Iron-based polyanionic sodium-ion battery positive electrode material Na 4 Fe x P 4 O 12+x The preparation process comprises the following steps:
s1, weighing raw materials: according to the general formula of material Na 4 Fe x P 4 O 12+x The dispersant, the water-soluble sodium source, the water-soluble iron source, the water-soluble phosphorus source and the water-soluble carbon source are weighed according to the stoichiometric ratio.
S2, adjusting the pH value of the solution: : the pH value of water is adjusted to 2 by using citric acid, and a water-soluble iron source is added to form a ferric citrate complex.
S3, preparing a precursor solution: and (3) adding a dispersing agent, a sodium source, a phosphorus source and a carbon source into the solution obtained in the step (2) to form a precursor solution. Wherein the solid content of the solution is 20wt%, the dispersant accounts for 5wt% of the total solid content of the solution, and the carbon source accounts for 5wt% of the total solid content of the solution.
S4, spray drying: and (4) carrying out spray drying on the precursor solution in the step (S3) to obtain dry precursor powder.
S5, sintering of precursor powder: and (4) sintering the precursor powder in the step (S4) at high temperature to obtain the polyanionic sodium-electrode anode material. Wherein the sintering temperature is 500 ℃, and the sintering time is 10H.
In this embodiment. Na (Na) 4 Fe x P 4 O 12+x Wherein x =2; belonging to triclinic system P-1/monoclinic system P2 1 One of the space groups/c, the lattice parameter of the active material varies within the range of:
Figure BDA0003851005930000081
61.2≦α°≦65.6、81.3≦β°≦87.9、71.2≦γ°≦75.8、
Figure BDA0003851005930000082
in this embodiment, in step S1, the dispersing agent is polyvinyl alcohol and polyethylene glycol, the water-soluble sodium source is sodium sulfate, the water-soluble iron source is ferrous sulfate and ferric sulfate, the water-soluble phosphorus source is phosphoric acid and ammonium dihydrogen phosphate, and the water-soluble carbon source is citric acid and glucose.
Example 2
Iron-based polyanionic sodium-ion battery positive electrode material Na 4 Fe x P 4 O 12+x The preparation process comprises the following steps:
s1, weighing raw materials: according to the general formula of material Na 4 Fe x P 4 O 12+x The dispersant, the water-soluble sodium source, the water-soluble iron source, the water-soluble phosphorus source and the water-soluble carbon source are weighed according to the stoichiometric ratio in the step (A).
S2, adjusting the pH value of the solution: : adjusting pH of water to 1 with citric acid, and adding water soluble iron source to form ferric citrate complex.
S3, preparing a precursor solution: and (3) adding a dispersing agent, a sodium source, a phosphorus source and a carbon source into the solution obtained in the step (2) to form a precursor solution. Wherein the solution has a solids content of 40 wt.%. The dispersant accounted for 8wt% of the total solid content in the solution, and the carbon source accounted for 4wt% of the total solid content in the solution.
S4, spray drying: and (4) carrying out spray drying on the precursor solution in the step (S3) to obtain dry precursor powder.
S5, sintering of precursor powder: and (4) sintering the precursor powder in the step (S4) at high temperature to obtain the polyanionic sodium-electrode anode material. Wherein the sintering temperature is 500 ℃, and the sintering time is 12H.
In this embodiment. Na (Na) 4 Fe x P 4 O 12+x Wherein x =2; belonging to triclinic system P-1/monoclinic system P2 1 One of the space groups/c, the lattice parameter of the active material varies within the range of:
Figure BDA0003851005930000083
61.2≦α°≦65.6、81.3≦β°≦87.9、71.2≦γ°≦75.8、
Figure BDA0003851005930000084
in this example, in step S1, the dispersants are polypropylene glycol and polyethylene oxide, the water-soluble sodium sources are sodium nitrate and sodium citrate, the water-soluble iron sources are iron formate and iron acetate, the water-soluble phosphoric acids are sodium monohydrogen phosphate and sodium dihydrogen phosphate, and the water-soluble carbon sources are citric acid and maltose.
Example 3
Iron-based polyanionic sodium-ion battery positive electrode material Na 4 Fe x P 4 O 12+x The preparation process comprises the following steps:
s1, weighing raw materials: according to the general formula of material Na 4 Fe x P 4 O 12+x The dispersant, the water-soluble sodium source, the water-soluble iron source, the water-soluble phosphorus source and the water-soluble carbon source are weighed according to the stoichiometric ratio.
S2, adjusting the pH value of the solution: : adjusting pH of water to 3 with citric acid, and adding water soluble iron source to form ferric citrate complex.
S3, preparing a precursor solution: and (3) adding a dispersing agent, a sodium source, a phosphorus source and a carbon source into the solution obtained in the step (2) to form a precursor solution. Wherein the solid content of the solution is 30wt%, the dispersant accounts for 10wt% of the total solid content of the solution, and the carbon source accounts for 2wt% of the total solid content of the solution.
S4, spray drying: and (4) carrying out spray drying on the precursor solution in the step (S3) to obtain dry precursor powder.
S5, sintering of precursor powder: and (5) sintering the precursor powder in the step (S4) at a high temperature to obtain the polyanionic sodium-electricity anode material. Wherein the sintering temperature is 550 ℃, and the sintering time is 8H.
In this embodiment. Na (Na) 4 Fe x P 4 O 12+x Wherein x =2.93; belonging to the orthorhombic system Pn21a space group, and the lattice parameter variation range of the active material is as follows:
Figure BDA0003851005930000091
Figure BDA0003851005930000092
in this embodiment, in step S1, the dispersing agent is polytetrafluoroethylene and polyacrylic acid, the water-soluble sodium source is sodium citrate and sodium phosphate, the water-soluble iron source is ferric nitrate and ferrous ammonium sulfate, the water-soluble phosphorus source is phosphoric acid and sodium phosphate, and the water-soluble carbon source is citric acid and sucrose.
Example 4
Iron-based polyanionic sodium-ion battery positive electrode material Na 4 Fe x P 4 O 12+x The preparation process comprises the following steps:
s1, weighing raw materials: according to the general formula of material Na 4 Fe x P 4 O 12+x The dispersant, the water-soluble sodium source, the water-soluble iron source, the water-soluble phosphorus source and the water-soluble carbon source are weighed according to the stoichiometric ratio.
S2, adjusting the pH value of the solution: : adjusting pH of water to 4 with citric acid, and adding water soluble iron source to form ferric citrate complex.
S3, preparing a precursor solution: and (3) adding a dispersing agent, a sodium source, a phosphorus source and a carbon source into the solution obtained in the step (2) to form a precursor solution. Wherein the solid content of the solution is 25wt%, the dispersant accounts for 12wt% of the total solid content of the solution, and the carbon source accounts for 8wt% of the total solid content of the solution.
S4, spray drying: and (4) carrying out spray drying on the precursor solution in the step (S3) to obtain dry precursor powder.
S5, sintering of precursor powder: and (4) sintering the precursor powder in the step (S4) at high temperature to obtain the polyanionic sodium-electrode anode material. Wherein the sintering temperature is 550 ℃, and the sintering time is 14H.
In this embodiment. Na (Na) 4 Fe x P 4 O 12+x Wherein x =2.93; belonging to the orthorhombic system Pn21a space group, and the lattice parameter variation range of the active material is as follows:
Figure BDA0003851005930000093
Figure BDA0003851005930000094
in this embodiment, in step S1, the dispersant is polymethyl acrylate and carboxymethyl cellulose, the water-soluble sodium source is sodium phosphate and sodium monohydrogen phosphate, the water-soluble iron source is ferrous sulfate and ammonium ferrous sulfate, the water-soluble phosphorus source is sodium monohydrogen phosphate and phosphoric acid, and the water-soluble carbon source is citric acid and lactose.
Example 5
Iron-based polyanionic sodium-ion battery positive electrode material Na 4 Fe x P 4 O 12+x The preparation process comprises the following steps:
s1, weighing raw materials: according to the general formula of material Na 4 Fe x P 4 O 12+x The dispersant, the water-soluble sodium source, the water-soluble iron source, the water-soluble phosphorus source and the water-soluble carbon source are weighed according to the stoichiometric ratio in the step (A).
S2, adjusting the pH value of the solution: : the pH value of water is adjusted to 2 by using citric acid, and a water-soluble iron source is added to form a ferric citrate complex.
S3, preparing a precursor solution: and (3) adding a dispersing agent, a sodium source, a phosphorus source and a carbon source into the solution obtained in the step (2) to form a precursor solution. Wherein the solid content of the solution is 35wt%, the dispersant accounts for 5wt% of the total solid content of the solution, and the carbon source accounts for 5wt% of the total solid content of the solution.
S4, spray drying: and (4) carrying out spray drying on the precursor solution in the step (S3) to obtain dry precursor powder.
S5, sintering of precursor powder: and (4) sintering the precursor powder in the step (S4) at high temperature to obtain the polyanionic sodium-electrode anode material. Wherein the sintering temperature is 600 ℃, and the sintering time is 6H.
In this embodiment. Na (Na) 4 Fe x P 4 O 12+x Wherein x =4; belonging to an orthorhombic system Pnma space group, and the lattice parameter variation range of the active material is as follows:
Figure BDA0003851005930000101
in this example, in step S1, the dispersants are methylcellulose and ethylcellulose, the water-soluble sodium sources are sodium acetate and sodium sulfate, the water-soluble iron sources are ferric sulfate and ferric acetate, the water-soluble phosphoric acid sources are ammonium dihydrogen phosphate and phosphoric acid, and the water-soluble carbon sources are citric acid and cyclodextrin.
Example 6
Iron-based polyanionic sodium-ion battery positive electrode material Na 4 Fe x P 4 O 12+x The preparation process comprises the following steps:
s1, weighing raw materials: according to the general formula of material Na 4 Fe x P 4 O 12+x The dispersant, the water-soluble sodium source, the water-soluble iron source, the water-soluble phosphorus source and the water-soluble carbon source are weighed according to the stoichiometric ratio.
S2, adjusting the pH value of the solution: : adjusting pH of water to 1 with citric acid, and adding water soluble iron source to form ferric citrate complex.
S3, preparing a precursor solution: and (3) adding a dispersing agent, a sodium source, a phosphorus source and a carbon source into the solution obtained in the step (2) to form a precursor solution. Wherein the solid content of the solution is 40wt%, the dispersant accounts for 10wt% of the total solid content of the solution, and the carbon source accounts for 5wt% of the total solid content of the solution.
S4, spray drying: and (4) carrying out spray drying on the precursor solution in the step (S3) to obtain dry precursor powder.
S5, sintering of precursor powder: and (4) sintering the precursor powder in the step (S4) at high temperature to obtain the polyanionic sodium-electrode anode material. Wherein the sintering temperature is 600 ℃, and the sintering time is 13H.
In this embodiment. Na (Na) 4 Fe x P 4 O 12+x Wherein x =4; belonging to an orthorhombic system Pnma space group, and the lattice parameter variation range of the active material is as follows:
Figure BDA0003851005930000102
in this embodiment, in step S1, the dispersants are carboxyethyl cellulose and carboxypropyl methyl cellulose, the water-soluble sodium sources are sodium dihydrogen phosphate, sodium sulfate, and sodium acetate, the water-soluble iron sources are ferrous sulfate, ferric formate, ferric acetate, and ferric nitrate, the water-soluble phosphorus sources are phosphoric acid, sodium dihydrogen phosphate, and ammonium dihydrogen phosphate, and the water-soluble carbon sources are citric acid and water-soluble starch.
Example 7
Cobalt-based polyanionic sodium-ion battery positive electrode material Na 4 Co x P 4 O 12+x The preparation process comprises the following steps:
s1, weighing raw materials: according to the general formula of material Na 4 Co x P 4 O 12+x The dispersant, the water-soluble sodium source, the water-soluble cobalt source, the water-soluble phosphorus source and the water-soluble carbon source are weighed according to the stoichiometric ratio.
S2, adjusting the pH value of the solution: : the pH of the water was adjusted to 2 using citric acid and a water soluble cobalt source was added to form a cobalt citrate complex.
S3, preparing a precursor solution: and (3) adding a dispersing agent, a sodium source, a phosphorus source and a carbon source into the solution obtained in the step (2) to form a precursor solution. Wherein the solid content of the solution is 20wt%, the dispersant accounts for 5wt% of the total solid content of the solution, and the carbon source accounts for 5wt% of the total solid content of the solution.
S4, spray drying: and (4) carrying out spray drying on the precursor solution in the step (S3) to obtain dry precursor powder.
S5, sintering of precursor powder: and (4) sintering the precursor powder in the step (S4) at high temperature to obtain the polyanionic sodium-electrode anode material. Wherein the sintering temperature is 600 ℃, and the sintering time is 12H.
In this embodiment. Na (Na) 4 Fe x P 4 O 12+x Wherein x =3; belonging to the orthorhombic system Pn21a space group, and the lattice parameter variation range of the active material is as follows:
Figure BDA0003851005930000111
Figure BDA0003851005930000112
in this embodiment, in step S1, the dispersing agent is polyvinyl alcohol and polyethylene glycol, the water-soluble sodium source is sodium sulfate, the water-soluble cobalt source is cobalt sulfate, the water-soluble phosphorus source is phosphoric acid and ammonium dihydrogen phosphate, and the water-soluble carbon source is citric acid and glucose.
Example 8
Positive electrode material Na of manganese-based polyanion sodium-ion battery 4 Mn x P 4 O 12+x The preparation process comprises the following steps:
s1, weighing raw materials: according to the general formula of material Na 4 Mn x P 4 O 12+x The dispersant, the water-soluble sodium source, the water-soluble manganese source, the water-soluble phosphorus source and the water-soluble carbon source are weighed according to the stoichiometric ratio.
S2, adjusting the pH value of the solution: : the pH value of the water is adjusted to 2 by using citric acid, and a water-soluble manganese source is added to form a manganese citrate complex.
S3, preparing a precursor solution: and (3) adding a dispersing agent, a sodium source, a phosphorus source and a carbon source into the solution obtained in the step (2) to form a precursor solution. Wherein the solid content of the solution is 20wt%, the dispersant accounts for 5wt% of the total solid content of the solution, and the carbon source accounts for 5wt% of the total solid content of the solution.
S4, spray drying: and (4) carrying out spray drying on the precursor solution in the step (S3) to obtain dry precursor powder.
S5, sintering of precursor powder: and (4) sintering the precursor powder in the step (S4) at high temperature to obtain the polyanionic sodium-electrode anode material. Wherein the sintering temperature is 550 ℃, and the sintering time is 11H.
In this embodiment. Na (Na) 4 Mn x P 4 O 12+x Wherein x =2; belonging to triclinic system P-1/monoclinic system P2 1 One of the space group/c, the lattice parameter of the active material varies within a range of:
Figure BDA0003851005930000113
Figure BDA0003851005930000121
61.2≦α°≦65.6、81.3≦β°≦87.9、71.2≦γ°≦75.8、
Figure BDA0003851005930000122
in this embodiment, in step S1, the dispersing agents are methylcellulose and ethylcellulose, the water-soluble sodium sources are sodium acetate and sodium sulfate, the water-soluble manganese sources are manganese sulfate and manganese acetate, the water-soluble phosphoric acids are ammonium dihydrogen phosphate and phosphoric acid, and the water-soluble carbon sources are citric acid and cyclodextrin.
Example 9
Positive electrode material Na of nickel-based polyanionic sodium-ion battery 4 Ni x P 4 O 12+x The preparation process comprises the following steps:
s1, weighing raw materials: according to the general formula of material Na 4 Ni x P 4 O 12+x The dispersant, the water-soluble sodium source, the water-soluble nickel source, the water-soluble phosphorus source and the water-soluble carbon source are weighed according to the stoichiometric ratio.
S2, adjusting the pH value of the solution: : the pH of the water was adjusted to 4 using citric acid and a water soluble nickel source was added to form a nickel citrate complex.
S3, preparing a precursor solution: and (3) adding a dispersing agent, a sodium source, a phosphorus source and a carbon source into the solution obtained in the step (2) to form a precursor solution. Wherein the solid content of the solution is 25wt%, the dispersant accounts for 12wt% of the total solid content of the solution, and the carbon source accounts for 8wt% of the total solid content of the solution.
S4, spray drying: and (4) carrying out spray drying on the precursor solution in the step (S3) to obtain dry precursor powder.
S5, sintering of precursor powder: and (5) sintering the precursor powder in the step (S4) at a high temperature to obtain the polyanionic sodium-electricity anode material. Wherein the sintering temperature is 600 ℃, and the sintering time is 8H.
In this embodiment. Na (Na) 4 Ni x P 4 O 12+x Wherein x =2.93; belonging to the orthorhombic system Pn21a space group, and the lattice parameter variation range of the active material is as follows:
Figure BDA0003851005930000123
Figure BDA0003851005930000124
in this embodiment, in step S1, the dispersant is carboxymethyl cellulose, the water-soluble sodium source is sodium phosphate, the water-soluble nickel source is nickel sulfate, the water-soluble phosphorus source is sodium monohydrogen phosphate, and the water-soluble carbon source is lactose.
Application example 1
Iron-based polyanionic sodium-ion battery positive electrode material Na 4 Fe 2.93 P 4 O 14.93 The preparation process comprises the following steps:
s1, weighing raw materials: according to the formula Na 4 Fe 2.93 P 4 O 14.93 Weighing sodium dihydrogen phosphate, ferrous sulfate and a carbon source according to the stoichiometric ratio.
S2, dissolving ferrous sulfate: adding citric acid into the aqueous solution to make the pH value to be 3, adding ferrous sulfate, and uniformly stirring to form a ferric citrate complex.
S3, preparing a precursor solution: and adding sodium dihydrogen phosphate, glucose, water-soluble starch and polyvinyl alcohol 4000 into the S2 solution to form a precursor solution. Wherein the solid content of the solution is 40wt%, glucose accounts for 3wt% of the total solid content of the solution, water-soluble starch accounts for 2wt% of the total solid content of the solution, and polyvinyl alcohol 4000 accounts for 7wt% of the total solid content of the solution.
S4, spray drying: and (3) spray-drying the precursor solution in the step (S3), controlling the air outlet temperature at 100 ℃, ensuring that the powder is not melted on the inner wall of a spray-drying instrument and does not have the phenomenon of wall adhesion, and ensuring that the collected powder is placed in the air and does not have the phenomenon of moisture absorption and adhesion. The detailed parameters are shown in table 1.
S5, sintering of precursor powder: and sintering the precursor powder in the S4 at high temperature. Wherein the sintering temperature is 550 ℃, and the sintering time is 10H.
FIG. 1 is iron-based polyanionic Na 4 Fe 2.93 P 4 O 14.93 Morphology of the material, it can be seen that it presents regular spheresThe particles are formed, the diameter is about 1-5um, the dispersion is better, and the bonding phenomenon among the particles does not exist.
FIG. 2 shows iron-based polyanionic Na 4 Fe 2.93 P 4 O 14.93 The XRD of the material shows a stronger diffraction peak, and no other impurity peaks appear, which indicates that the crystallinity is good and the phase purity is high.
Polyanionic Na of iron group 4 Fe 2.93 P 4 O 14.93 After mixing acetylene black and PVDF in a mass ratio of 8. Punching the electrode film to a round piece with the radius of 0.6mm by using a punching machine, wherein the loading capacity of the active substance is about 2.5mg/cm 2 Using metallic sodium as a counter electrode, 1mol/L NaClO 4 EC + DEC (1 vol%) +5% fec as electrolyte, glass fiber as separator, assembled into CR2016 type coin cells in a glove box. FIG. 3 is Na 4 Fe 2.93 P 4 O 14.93 According to the initial cycle charge and discharge curve of the electrode, the current density is 0.1C (1C= 110mAh/g), the reversible discharge specific capacity is 110mAh/g, the initial cycle coulombic efficiency is 90%, and the electrode has almost no attenuation and shows excellent electrochemical performance after 100 cycles under the 1C multiplying power (see figure 4).
Application example 2
Iron-based polyanionic sodium-ion battery positive electrode material Na 4 Fe 2 P 4 O 14 The preparation process comprises the following steps:
s1, weighing raw materials: according to the formula Na 4 Fe 2 P 4 O 14 Weighing sodium acetate, ammonium dihydrogen phosphate, ferrous sulfate and a carbon source according to the stoichiometric ratio.
S2, dissolving ferrous sulfate: adding citric acid into the aqueous solution to make the pH value be 2, adding ferrous sulfate, and uniformly stirring to form a ferric citrate complex.
S3, preparing a precursor solution: adding sodium acetate, ammonium dihydrogen phosphate, sucrose, water-soluble starch and carboxymethyl cellulose into the S2 solution to form a precursor solution. Wherein the solid content of the solution is 30wt%, the sucrose accounts for 1wt% of the total solid content of the solution, the water-soluble starch accounts for 3wt% of the total solid content of the solution, and the carboxymethyl cellulose accounts for 9wt% of the total solid content of the solution.
S4, spray drying: and (3) spray-drying the precursor solution in the step (S3), controlling the air outlet temperature at 100 ℃, ensuring that the powder is not melted on the inner wall of a spray-drying instrument and does not have the phenomenon of wall adhesion, and ensuring that the collected powder is placed in the air and does not have the phenomenon of moisture absorption and adhesion. The detailed parameters are shown in table 1.
S5, sintering of precursor powder: and sintering the precursor powder in the S4 at high temperature. Wherein the sintering temperature is 500 ℃, and the sintering time is 12H. As shown in Table 2, na 4 Fe 2 P 4 O 14 The material appears as a single pure phase. The electrode and sodium metal are assembled into a half-cell, the result shows that the reversible discharge specific capacity of the electrode is 98mAh/g (0.1C, 1C = 98mAh/g), the first-week coulombic efficiency is 105%, and the electrode has almost no attenuation and shows excellent electrochemical performance after 100-week circulation under the 1C multiplying power.
Application example 3
Iron-based polyanionic sodium-ion battery positive electrode material Na 4 Fe 4 P 4 O 16 The preparation process comprises the following steps:
s1, weighing raw materials: according to the formula Na 4 Fe 4 P 4 O 16 Weighing sodium sulfate, sodium acetate, phosphoric acid, ammonium dihydrogen phosphate, ferrous sulfate and a carbon source according to the stoichiometric ratio.
S2, dissolving ferrous sulfate: adding citric acid into the aqueous solution to make the pH value be 4, adding ferrous sulfate, and uniformly stirring to form a ferric citrate complex.
S3, preparing a precursor solution: adding sodium sulfate, sodium acetate, phosphoric acid, ammonium dihydrogen phosphate, glucose, sucrose, water-soluble starch and polyacrylic acid into the S2 solution to form a precursor solution. Wherein the solid content of the solution is 20wt%, glucose accounts for 2wt% of the total solid content of the solution, sucrose accounts for 2wt% of the total solid content of the solution, water-soluble starch accounts for 2wt% of the total solid content of the solution, and polyacrylic acid accounts for 10wt% of the total solid content of the solution.
S4, spray drying: and (3) spray-drying the precursor solution in the step (S3), controlling the air outlet temperature at 100 ℃, ensuring that the powder is not melted on the inner wall of a spray-drying instrument and does not have the phenomenon of wall adhesion, and ensuring that the collected powder is placed in the air and does not have the phenomenon of moisture absorption and adhesion. The detailed parameters are shown in Table 1.
S5, sintering of precursor powder: and sintering the precursor powder in the S4 at high temperature to obtain the polyanion type sodium-electricity anode material. Wherein the sintering temperature is 600 ℃, and the sintering time is 10H. As shown in Table 2, na 4 Fe 4 P 4 O 16 The material appears as a single pure phase. Further, na 4 Fe 4 P 4 O 16 Is an electrochemically inert material and therefore its electrochemical performance is not tested.
Application example 4
Manganese-based polyanionic sodium-ion battery positive electrode material Na 4 Mn 2.93 P 4 O 14.93 The preparation process comprises the following steps:
s1, weighing raw materials: according to the formula Na 4 Mn 2.93 P 4 O 14.93 Weighing sodium dihydrogen phosphate, manganese sulfate and a carbon source according to the stoichiometric ratio.
S2, dissolving manganese sulfate: adding citric acid into the aqueous solution to make the pH value be 3, adding manganese sulfate, and uniformly stirring to form a manganese citrate complex.
S3, preparing a precursor solution: and adding sodium dihydrogen phosphate, glucose, water-soluble starch and polyvinyl alcohol 4000 into the S2 solution to form a precursor solution. Wherein the solid content of the solution is 40wt%, the glucose accounts for 3wt% of the total solid content of the solution, the water-soluble starch accounts for 2wt% of the total solid content of the solution, and the polyvinyl alcohol 4000 accounts for 7wt% of the total solid content of the solution.
S4, spray drying: and (4) spray-drying the precursor solution in the step (S3), controlling the air outlet temperature at 100 ℃, ensuring that the powder is not melted on the inner wall of a spray-drying instrument and does not have the phenomenon of wall adhesion, and ensuring that the collected powder is placed in the air and does not have the phenomenon of moisture absorption and adhesion. The detailed parameters are shown in table 1.
S5, sintering of precursor powder: and sintering the precursor powder in the S4 at high temperature. Wherein the sintering temperature is 550 ℃, and the sintering time is 10H.
Polyanionic Na of manganese group 4 Mn 2.93 P 4 O 14.93 After mixing acetylene black and PVDF in a mass ratio of 8. Using a tablet punching machine to punch the electrode film to a wafer with the radius of 0.6mm, wherein the active substance loading is about 2.5mg/cm 2 Using metal sodium as counter electrode, 1mol/L NaClO 4 EC + DEC (1 vol%) +5%fec was electrolyte solution, glass fiber as separator, assembled in a glove box into CR2016 type coin cells. The results show that when the current density is 0.1C (1C = 110mAh/g), the reversible discharge specific capacity is 90mAh/g, the first cycle coulombic efficiency is 92%, and the electrode has almost no attenuation and shows excellent electrochemical performance after 100 cycles under the 1C multiplying power. The detailed parameters are shown in table 1.
Comparative example 1
Iron-based polyanionic sodium-ion battery positive electrode material Na 4 Fe 2.93 P 4 O 14.93 The preparation process comprises the following steps:
s1, weighing raw materials: according to the formula Na 4 Fe 2.93 P 4 O 14.93 Weighing sodium dihydrogen phosphate, ferrous sulfate and a carbon source according to the stoichiometric ratio.
S2, dissolving ferrous sulfate: adding ferrous sulfate into the water solution, and stirring uniformly, wherein the pH value is 6.
S3, preparing a precursor solution: sodium dihydrogen phosphate, glucose, water-soluble starch and PEG2000 were added to the S2 solution to form a precursor solution. Since the solution is neutral, a large amount of ferrous phosphate precipitates. Wherein the solid content of the solution is 40wt%, glucose accounts for 3wt% of the total solid content of the solution, water-soluble starch accounts for 2wt% of the total solid content of the solution, and PEG2000 accounts for 7wt% of the total solid content of the solution.
S4, spray drying: and (3) spray-drying the precursor solution in the step (S3), controlling the air outlet temperature at 100 ℃, ensuring that the powder is not melted on the inner wall of a spray-drying instrument and does not have the phenomenon of wall adhesion, and ensuring that the collected powder is placed in the air and does not have the phenomenon of moisture absorption and adhesion. The detailed parameters are shown in Table 1.
S5, sintering of precursor powder: and sintering the precursor powder in the S4 at high temperature. Wherein the sintering temperature is 550 ℃, and the sintering time is 10H.
FIG. 5 shows iron-based polyanionic Na 4 Fe 2.93 P 4 O 14.93 The XRD of the material has NaFePO4 impurity peak on the curve, which is mainly caused by the fact that the solution PH is neutral, a large amount of ferrous phosphate precipitation is generated, and Na, fe and PO4 are distributed unevenly.
Polyanionic Na of iron group 4 Fe 2.93 P 4 O 14.93 After mixing acetylene black and PVDF in a mass ratio of 8. Using a tablet punching machine to punch the electrode film to a wafer with the radius of 0.6mm, wherein the active substance loading is about 2.5mg/cm 2 Using metal sodium as counter electrode, 1mol/L NaClO 4 EC + DEC (1 vol%) +5% fec as electrolyte, glass fiber as separator, assembled into CR2016 type coin cells in a glove box. FIG. 6 shows Na 4 Fe 2.93 P 4 O 14.93 The first cycle charge and discharge curve of the electrode has the current density of 0.1C (1C = 110mAh/g), the reversible discharge specific capacity of 82mAh/g and the first cycle coulombic efficiency of 85 percent, and the capacity retention rate of the electrode is only 81 percent under the 1C multiplying power after 100 cycles, and the capacity attenuation can be influenced by an impurity phase (see figure 7).
Comparative example 2
Iron-based polyanionic sodium-ion battery positive electrode material Na 4 Fe 2 P 4 O 14 The preparation process comprises the following steps:
s1, weighing raw materials: according to the formula Na 4 Fe 2 P 4 O 14 Weighing sodium acetate, ammonium dihydrogen phosphate, ferrous sulfate and a carbon source according to the stoichiometric ratio.
S2, dissolving ferrous sulfate: adding citric acid into the aqueous solution to make the pH value be 2, adding ferrous sulfate, and uniformly stirring to form a ferric citrate complex.
S3, preparing a precursor solution: adding sodium acetate, ammonium dihydrogen phosphate, sucrose and water-soluble starch into the S2 solution to form a precursor solution. Wherein the solid content of the solution is 30wt%, the sucrose accounts for 1wt% of the total solid content of the solution, and the water-soluble starch accounts for 3wt% of the total solid content of the solution.
S4, spray drying: and (3) spray-drying the precursor solution in the step (S3), controlling the air outlet temperature at 100 ℃, and ensuring that the powder is melted on the inner wall of a spray-drying instrument and seriously adhered to the wall, so that the material cannot be normally collected. The detailed parameters are shown in Table 1.
S5, sintering of precursor powder: and taking down the precursor adhered to the inner wall of the instrument in the step S4 for sintering. Wherein the sintering temperature is 500 ℃, and the sintering time is 12H.
FIG. 8 shows iron-based polyanionic Na 4 Fe 2 P 4 O 14 The morphology of the material shows that the particle size is not uniform and the agglomeration phenomenon is serious, which is consistent with the powder melting and wall sticking in the spray drying process. In addition, the material contains multiple impurity phases, which may be associated with uneven ion distribution during spray drying, indicating that the process is not suitable for large-scale production.
Comparative example 3
Iron-based polyanionic sodium-ion battery positive electrode material Na 4 Fe 4 P 4 O 16 The preparation process comprises the following steps:
s1, weighing raw materials: according to the formula Na 4 Fe 4 P 4 O 16 Weighing sodium sulfate, sodium acetate, phosphoric acid, ammonium dihydrogen phosphate, ferrous sulfate and a carbon source according to the stoichiometric ratio.
S2, dissolving ferrous sulfate: adding ferrous sulfate into the water solution, stirring and dissolving, wherein the pH value is 6.
S3, preparing a precursor solution: sodium sulfate, sodium acetate, phosphoric acid, ammonium dihydrogen phosphate, glucose, sucrose and water-soluble starch are added into the S2 solution to form a precursor solution. Wherein the solid content of the solution is 20wt%, the glucose accounts for 2wt% of the total solid content of the solution, the sucrose accounts for 2wt% of the total solid content of the solution, and the water-soluble starch accounts for 2wt% of the total solid content of the solution.
S4, spray drying: and (3) spray-drying the precursor solution in the step (S3), controlling the air outlet temperature at 100 ℃, and ensuring that the powder is melted on the inner wall of a spray-drying instrument and seriously adhered to the wall, so that the material cannot be normally collected. The detailed parameters are shown in table 1.
Comparative example 4
Positive electrode material Na of manganese-based polyanion sodium-ion battery 4 Mn 2.93 P 4 O 14.93 The preparation process comprises the following steps:
s1, weighing raw materials: according to the formula Na 4 Mn 2.93 P 4 O 14.93 Weighing sodium dihydrogen phosphate, manganese sulfate and a carbon source according to the stoichiometric ratio.
S2, dissolving ferrous sulfate: adding manganese sulfate into the water solution, and uniformly stirring the mixture to obtain the solution with the pH value of 6.
S3, preparing a precursor solution: sodium dihydrogen phosphate, glucose, water-soluble starch and PEG2000 were added to the S2 solution to form a precursor solution. Because the solution is neutral, a large amount of manganese phosphate precipitates. Wherein the solid content of the solution is 40wt%, glucose accounts for 3wt% of the total solid content of the solution, water-soluble starch accounts for 2wt% of the total solid content of the solution, and PEG2000 accounts for 7wt% of the total solid content of the solution.
S4, spray drying: and (3) spray-drying the precursor solution in the step (S3), controlling the air outlet temperature at 100 ℃, ensuring that the powder is not melted on the inner wall of a spray-drying instrument and does not have the phenomenon of wall adhesion, and ensuring that the collected powder is placed in the air and does not have the phenomenon of moisture absorption and adhesion. The detailed parameters are shown in table 1.
S5, sintering of precursor powder: and sintering the precursor powder in the S4 at high temperature. Wherein the sintering temperature is 550 ℃, and the sintering time is 10H.
Polyanionic Na of manganese group 4 Mn 2.93 P 4 O 14.93 After mixing acetylene black and PVDF in a mass ratio of 8. Using a tablet punching machine to punch the electrode film to a wafer with the radius of 0.6mm, wherein the active substance loading is about 2.5mg/cm 2 Using metal sodium as counter electrode, 1mol/L NaClO 4 EC + DEC (1 vol%) +5% fec as electrolyte, glass fiber as separator, assembled into CR2016 type coin cells in a glove box. The results show that when the current density is 0.1C (1c = 110mah/g), the reversible discharge specific capacity is 63mAh/g, the first cycle coulombic efficiency is 80%, and the capacity retention rate of the electrode is only 76% after 100 cycles under the 1C rate, and the capacity attenuation may be caused by the influence of the impurity phase. The detailed parameters are shown in tables 1-2.
TABLE 1 carbon source ratios of series materials
Figure BDA0003851005930000171
Figure BDA0003851005930000181
TABLE 2 electrochemical Performance test results
Figure BDA0003851005930000182
Examples 1 to 6, application examples 1 to 3, and comparative examples 1 to 3 although only the iron-based polyanionic sodium-ion battery positive electrode material was described. However, other metal bases are within the scope of the present invention.
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 various changes and modifications as would be obvious to one having the ordinary skill in this art may be made without departing from the spirit and scope of the invention, and such obvious alternatives are intended to be included within the scope of the invention.

Claims (10)

1. A polyanion type sodium ion battery positive electrode material is characterized in that: the general formula of the polyanion type sodium ion battery anode material is Na 4 M x P 4 O 12+x Wherein, the value range of x is more than or equal to 2.0 and less than or equal to 4.0, M is one or more than two of Fe, co, ni, cu, zn and Mn;
by controlling the change of the x value, the polyanionic sodium-ion battery anode material is single-phase or two-phase.
2. The polyanionic sodium-ion battery positive electrode material according to claim 1, wherein: when x =2.0, the polyanionic sodium-ion battery positive electrode material is Na 4 M 2 P 4 O 14 The structure of which belongs to a triclinic system P-1/monoclinic system P2 1 One of the/c space groups.
3. The polyanionic sodium-ion battery positive electrode material according to claim 1, wherein: when 2.9<x<At 2.97, the polyanionic sodium-ion battery positive electrode material is Na 4 M x P 4 O 12+x The structure belongs to the orthorhombic Pn21a space group.
4. The polyanionic sodium-ion battery positive electrode material according to claim 1, wherein: when x =4.0, the polyanionic sodium-ion battery positive electrode material is Na 4 M 4 P 4 O 16 The structure belongs to the orthorhombic Pnma space group.
5. The polyanionic sodium-ion battery positive electrode material according to claim 1, wherein the positive electrode material is characterized in thatIn the following steps: when 2.0<When x is less than or equal to 2.9, the polyanionic sodium-ion battery positive electrode material is Na 4 M x P 4 O 12+x The structure is triclinic P-1/monoclinic P2 1 A two-phase mixture of/c and the space group of orthorhombic Pn21 a.
6. The polyanionic sodium-ion battery positive electrode material according to claim 1, wherein: when x is more than or equal to 2.97<At 4.0, the polyanionic sodium-ion battery positive electrode material is Na 4 M x P 4 O 12+x The structure is a two-phase mixture of the orthorhombic Pn21a and orthorhombic Pnma space groups.
7. The method for producing a polyanionic sodium-ion battery positive electrode material according to any one of claims 1 to 6, characterized by comprising the steps of:
s1, weighing the following raw materials: according to the different values of x, according to the general formula of the material Na 4 M x P 4 O 12+x Weighing a dispersing agent, a water-soluble sodium source, a water-soluble metal source, a water-soluble phosphorus source and a water-soluble carbon source according to the stoichiometric ratio;
s2, adjusting the pH value of the solution: adjusting the pH value of water to 1-4 by using citric acid, adding a water-soluble metal source to form a citric acid-metal complex, and further avoiding uneven ion distribution caused by the generation of metal phosphate precipitates when a subsequent phosphorus source is introduced;
s3, preparing a precursor solution: adding a dispersing agent, a sodium source, a phosphorus source and a water-soluble carbon source into the solution obtained in the step S2 to form a precursor solution;
s4, spray drying: spray drying the precursor solution in the step S3 to obtain dried precursor powder;
s5, sintering of precursor powder: and (4) sintering the precursor powder in the step (S4) at high temperature to obtain the polyanionic sodium-electrode anode material.
8. The method for preparing the polyanionic sodium-ion battery positive electrode material according to claim 7, wherein the method comprises the following steps: in the precursor solution obtained in the step S3, the solid content of the solution is 10-50 wt%, the dispersing agent accounts for 1-15 wt% of the total solid content of the solution, and the water-soluble carbon source accounts for 1-10 wt% of the total solid content of the solution;
preferably, in the sintering of the precursor powder in step S5, the sintering conditions are: the sintering temperature interval is 450-650 ℃, and the sintering time is 5-15H.
9. The method for preparing the polyanionic sodium-ion battery positive electrode material according to claim 7, wherein the method comprises the following steps:
the dispersant is one or more of polyvinyl alcohol, polyethylene glycol, polypropylene glycol, polyethylene oxide, polytetrafluoroethylene, polyacrylic acid, polymethyl acrylate, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, carboxyethyl cellulose, carboxypropyl methyl cellulose and carboxyethyl methyl cellulose;
preferably, wherein the water-soluble sodium source is one or more of sodium formate, sodium acetate, sodium sulfate, sodium nitrate, sodium citrate, sodium phosphate, mono/di sodium phosphate and sodium chloride;
preferably wherein the water soluble source of phosphorus is one or more of phosphoric acid, ammonium dihydrogen phosphate, sodium monohydrogen/dihydrogen phosphate, and sodium phosphate;
preferably, the water-soluble carbon source is citric acid, glucose, sucrose, maltose, lactose, cyclodextrin and water-soluble starch.
10. The method for preparing the polyanionic sodium-ion battery positive electrode material according to claim 7, wherein the method comprises the following steps:
the water-soluble metal source is a water-soluble iron source, a water-soluble cobalt source, a water-soluble nickel source, a water-soluble zinc source, a water-soluble manganese source and/or a water-soluble copper source;
wherein the water-soluble iron source is one or more of ferric sulfate/ferrous iron, ferric formate, ferric acetate, ferric nitrate and ferrous ammonium sulfate.
Wherein the water-soluble cobalt source is one or more of cobalt sulfate, cobalt acetate, cobalt nitrate and cobalt chloride.
Wherein the water-soluble nickel source is one or more of nickel sulfate, nickel chloride and nickel nitrate.
Wherein the water soluble zinc source is one or more of zinc sulfate, zinc acetate, zinc chloride, zinc nitrate and zinc gluconate.
Wherein the water-soluble manganese source is one or more of manganese acetate, manganese sulfate, manganese nitrate and manganese chloride.
Wherein the water-soluble copper source is one or more of copper nitrate, copper sulfate, copper chloride, copper acetate and copper perchlorate.
CN202211133667.XA 2022-09-19 2022-09-19 Polyanion type sodium ion battery positive electrode material and preparation method thereof Pending CN115513452A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115924980A (en) * 2022-12-26 2023-04-07 江苏贝特瑞纳米科技有限公司 Preparation method of iron-based sodium-ion battery layered positive electrode material precursor of composite phosphate

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115924980A (en) * 2022-12-26 2023-04-07 江苏贝特瑞纳米科技有限公司 Preparation method of iron-based sodium-ion battery layered positive electrode material precursor of composite phosphate
CN115924980B (en) * 2022-12-26 2024-06-11 江苏贝特瑞纳米科技有限公司 Preparation method of iron-based sodium ion battery layered cathode material precursor of composite phosphate

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