Sodium-ion battery positive electrode material, preparation method of sodium-ion battery positive electrode material, sodium-ion battery and application

Abstract

The invention discloses a sodium-ion battery positive electrode material, a preparation method thereof, a sodium-ion battery and application, and relates to the technical field of positive electrode materials. The positive electrode material is a compound of Na4 (Fe) 1.5-X (Mn) 1.5-y (PO4) 2P2O7 and C, and 0 lt; xlt; 0, 0.5, 0 lt; yt; Yt; and 0.5. Raw materials including a sodium source, an iron source, a manganese source, a phosphorus source and a carbon source are mixed, sprayed and sintered. The invention also provides a sodium ion battery comprising the positive electrode material and application of the sodium ion battery in the technical field of energy storage. Iron and manganese defects are introduced into the Na4Fe1. 5Mn1. 5 (PO4) 2P2O7 structure of the sodium ion battery positive electrode material, the sodium ion battery positive electrode material can be simply prepared only by reducing the content of an iron source and a manganese source in the raw materials, a new production process is not needed, the product purity is high, the crystallinity is good, the energy density of the iron-based polyanion positive electrode material is greatly improved, and the iron-based polyanion positive electrode material is suitable for large-scale production and application.

Description

Technical Field

[0001] The present application relates to the technical field of cathode materials, in particular to a cathode material for a sodium-ion battery, a preparation method thereof, a sodium-ion battery and an application thereof. Background Art

[0002] Renewable energy sources such as solar energy, wind energy, and water energy have attracted more and more attention. However, these clean energies are intermittent and unstable, so large-scale energy storage devices are needed to integrate energy and use these clean energies more efficiently. Among various energy storage methods, electrochemical energy storage is considered to be one of the ideal energy storage options due to its stability and high efficiency.

[0003] Although lithium-ion batteries have achieved great success in the fields of 3C electronic devices and electric vehicles, lithium resources cannot meet the demands of both power batteries and energy storage batteries at the same time. On the other hand, the scarcity and uneven distribution of lithium resources are also important challenges faced by China's energy storage security. Sodium-ion batteries have gradually come into the sight of researchers because of their similar working principles to lithium-ion batteries and lower costs. Moreover, energy storage batteries pay more attention to the device cost, so sodium-ion batteries have broad application potential in the field of large-scale energy storage.

[0004] In sodium-ion batteries, cathode materials are mainly divided into layered oxides, Prussian blue and its analogues, and polyanion compounds. Among them, sodium iron pyrophosphate has low cost and excellent cycle life, and has great application potential. However, sodium iron pyrophosphate has a low working voltage, resulting in a low energy density, which limits its further development; Mn 2+ radius Fe 2+ radii are similar, and can significantly improve the working platform, so sodium manganese iron pyrophosphate has broad application prospects. However, the synthesis of pure-phase sodium manganese iron pyrophosphate is currently difficult. According to the theoretical stoichiometric ratio of Na 4 Fe 1.5 Mn 1.5 (PO 4 ) 2 P 2 O 7 to synthesize the material, the crystallinity is poor, and impurities are always generated, seriously affecting its capacity performance and unable to meet the application requirements. Summary of the Invention

[0005] In order to solve at least one of the above technical problems and develop an energy storage battery with good capacity performance, the present application provides a preparation method of a cathode material for a sodium-ion battery, a sodium-ion battery and an application thereof.

[0006] On the one hand, a cathode material for a sodium-ion battery provided by the present application is Na 4 (Fe) 1.5-X (Mn)1.5-y (PO 4 ) 2 P 2 O 7 and C composite, where 0 < x < 0.5 and 0 < y < 0.5.

[0007] Optionally, the proportion of C is 1-5 wt%.

[0008] Optionally, the Na 4 (Fe) 1.5-X (Mn) 1.5-y (PO 4 ) 2 P 2 O 7 where x = y.

[0009] In a second aspect, the present application provides a method for preparing the above positive electrode material, comprising the following steps:

[0010] S1. Weigh the sodium source, iron source, phosphorus source, carbon source, and manganese source respectively, and add them to deionized water in sequence and stir to disperse to obtain a suspension, where the molar ratio of sodium, iron, and manganese is controlled to be 4:(1.5 - x):(1.5 - y), 0 < x < 0.5, 0 < y < 0.5;

[0011] S2. Grind the suspension prepared in S1 to nanoscale, and then obtain a precursor powder through spray drying treatment;

[0012] S3. Sinter the precursor powder prepared in S2 in an inert atmosphere to obtain the positive electrode material.

[0013] Optionally, the sodium source is one or more of disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium phosphate, sodium carbonate, sodium bicarbonate, sodium pyrophosphate, sodium oxalate, and sodium acetate;

[0014] and / or, the iron source is one or more of iron nitrate, iron phosphate, ferrous oxalate, iron oxide, magnetite, ferrous acetate, and iron acetylacetonate;

[0015] and / or, the phosphorus source is one or more of sodium dihydrogen phosphate, disodium hydrogen phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, sodium phosphate, sodium pyrophosphate, and phosphoric acid;

[0016] and / or, the carbon source is one or more of citric acid, ascorbic acid, oxalic acid, stearic acid, glucose, agarose, sucrose, cellulose, and polyethylene glycol;

[0017] and / or, the manganese source is one or more of manganese nitrate, manganese acetate, manganese oxalate, manganese sulfate, manganese chloride, and manganese(III) oxide.

[0018] Optionally, in S1, the stirring method for stirring and dispersing is one of mechanical stirring and magnetic stirring; the stirring speed is 100 rpm to 1200 rpm, the stirring temperature is 10 to 60 °C, and the stirring time is 1 to 10 h.

[0019] Optionally, in S2, the process of spray drying treatment is as follows: the inlet temperature is 200 to 260 °C, the outlet temperature is 90 to 110 °C, the fan speed is 90%, and the peristaltic pump speed is 40%.

[0020] Optionally, in S3, the inert atmosphere is one of argon, nitrogen, and hydrogen-argon mixed gas; the sintering method for the sintering treatment is two-stage sintering. The first stage is to keep the temperature at 300 to 350 °C for 3 to 6 hours, and the second stage is to keep the temperature at 500 to 600 °C for 10 to 15 hours. The heating rate from the temperature of the first stage to the temperature of the second stage is 1 to 5 °C / min.

[0021] In a third aspect, the present application provides a sodium-ion battery including the above-mentioned positive electrode material.

[0022] In a fourth aspect, the present application provides the application of the above-mentioned sodium-ion battery in the field of energy storage technology.

[0023] In summary, the present invention includes at least one of the following beneficial technical effects:

[0024] 1. Introduce iron-manganese defects into the Na 4 Fe 1.5 Mn 1.5 (PO 4 ) 2 P 2 O 7 structure of the positive electrode material of the sodium-ion battery. The iron-manganese vacancies can reduce the migration energy barrier of sodium ions and broaden the diffusion channels of sodium ions, thereby improving the ionic conductivity of the material; the iron-manganese defects can also change the electron cloud distribution of phosphorus and oxygen elements, improving the electronic conductivity; through structural distortion and electron rearrangement, the ionic conductivity and electronic conductivity of the material are improved, thereby increasing the energy density of the positive electrode material;

[0025] 2. By only controlling the contents of the iron source and manganese source during synthesis, impurities such as sodium manganese phosphate can be significantly reduced, and the synthesized material has good reversibility, and the common voltage hysteresis problem of manganese ions is significantly alleviated; the preparation method is simple and controllable, and the synthesized Na 4 (Fe) 1.5-X (Mn) 1.5-y (PO 4 ) 2 P 2 O 7 / C sodium-ion battery positive electrode material has high purity, good crystallinity, excellent performance, and is suitable for large-scale production. Description of the Drawings

[0026] Figure 1 XRD pattern of the cathode material prepared in Example 2 and Comparative Example 1 of this application;

[0027] Figure 2 First charge-discharge curve of the sodium-ion battery corresponding to Application Example 5 of this application;

[0028] Figure 3 First charge-discharge curve of the sodium-ion battery corresponding to Application Example 2 of this application;

[0029] Figure 4 First charge-discharge curve of the sodium-ion battery corresponding to Application Example 4 of this application;

[0030] Figure 5 Morphology diagrams of the cathode material prepared in Example 2 at different magnifications by FESEM. Detailed implementation mode

[0031] The following further elaborates on this application in conjunction with the drawings and examples.

[0032] In the following examples of this application, unless otherwise specified, the main components involved are all purchased from commercially available products.

[0033] The sodium source in the following examples of this application is exemplarily sodium carbonate;

[0034] The iron source in the following examples of this application is exemplarily ferric nitrate (ferric nitrate nonahydrate);

[0035] The phosphorus source in the following examples of this application is exemplarily ammonium dihydrogen phosphate;

[0036] The carbon source in the following examples of this application is exemplarily citric acid (citric acid monohydrate);

[0037] The manganese source in the following examples of this application is exemplarily manganese nitrate. Specific examples

[0039] Example 1

[0040] Dissolve sodium carbonate, ferric nitrate, manganese nitrate, ammonium dihydrogen phosphate, and citric acid in deionized water according to a molar ratio of 2:1.485:1.485:4:2, stir for 1 h to mix evenly, and then add it to a sand mill for sanding for 5 h to obtain a precursor suspension. Spray-dry the obtained suspension, with an inlet air temperature of 260 °C, an outlet air temperature of 120 °C, and a peristaltic pump of 40%, to obtain a precursor powder. Finally, under a nitrogen atmosphere, heat it to 350 °C at a rate of 3 °C per minute and hold for 5 hours, and then heat it to 600 °C at a rate of 3 °C per minute and hold for 10 hours to obtain Na 4 (Fe) 1.485 (Mn)1.485 (PO 4 ) 2 P 2 O 7 / C cathode material.

[0041] Example 2

[0042] Dissolve sodium carbonate, iron nitrate, manganese nitrate, ammonium dihydrogen phosphate, and citric acid in deionized water according to a molar ratio of 2:1.455:1.455:4:2, stir for 1 h to mix evenly, then add to a sand mill and grind for 5 h to obtain a precursor suspension. Spray-dry the obtained suspension, with an inlet air temperature of 260 °C, an outlet air temperature of 120 °C, and a peristaltic pump of 40%, to obtain a precursor powder. Finally, under a nitrogen atmosphere, heat to 350 °C at a rate of 3 °C per minute and hold for 5 hours, then heat to 600 °C at a rate of 3 °C per minute and hold for 10 hours to obtain Na 4 (Fe) 1.455 (Mn) 1.455 (PO 4 ) 2 P 2 O 7 / C cathode material.

[0043] Example 3

[0044] Dissolve sodium carbonate, iron nitrate, manganese nitrate, ammonium dihydrogen phosphate, and citric acid in deionized water according to a molar ratio of 2:1.425:1.425:4:2, stir for 1 h to mix evenly, then add to a sand mill and grind for 5 h to obtain a precursor suspension. Spray-dry the obtained suspension, with an inlet air temperature of 260 °C, an outlet air temperature of 120 °C, and a peristaltic pump of 40%, to obtain a precursor powder. Finally, under a nitrogen atmosphere, heat to 350 °C at a rate of 3 °C per minute and hold for 5 hours, then heat to 600 °C at a rate of 3 °C per minute and hold for 10 hours to obtain Na 4 (Fe) 1.425 (Mn) 1.425 (PO 4 ) 2 P 2 O 7 / C cathode material.

[0045] Example 4

[0046] Dissolve sodium carbonate, iron nitrate, manganese nitrate, ammonium dihydrogen phosphate, and citric acid in deionized water according to a molar ratio of 2:1.395:1.395:4:2, stir for 1 h to mix evenly, and then add it to a sand mill for sanding for 5 h to obtain a precursor suspension. Spray-dry the obtained suspension, with an inlet air temperature of 260 °C, an outlet air temperature of 120 °C, and a peristaltic pump of 40%, to obtain a precursor powder. Finally, under a nitrogen atmosphere, heat it to 350 °C at a rate of 3 °C per minute and hold for 5 hours, and then heat it to 600 °C at a rate of 3 °C per minute and hold for 10 hours to obtain Na 4 (Fe) 1.395 (Mn) 1.395 (PO 4 ) 2 P 2 O 7 / C cathode material.

[0047] Comparative Example 1

[0048] Dissolve sodium carbonate, iron nitrate, manganese nitrate, ammonium dihydrogen phosphate, and citric acid in deionized water according to a molar ratio of 2:1.5:1.5:4:2, stir for 1 h to mix evenly, and then add it to a sand mill for sanding for 5 h to obtain a precursor suspension. Spray-dry the obtained suspension, with an inlet air temperature of 260 °C, an outlet air temperature of 120 °C, and a peristaltic pump of 40%, to obtain a precursor powder. Finally, under a nitrogen atmosphere, heat it to 350 °C at a rate of 3 °C per minute and hold for 5 hours, and then heat it to 600 °C at a rate of 3 °C per minute and hold for 10 hours to obtain Na 4 (Fe) 1.5 (Mn) 1.5 (PO 4 ) 2 P 2 O 7 / C cathode material.

[0049] As Figure 1 shown, the XRD test results of Comparative Example 1 and Example 2 show that when we reduce the amounts of iron and manganese, the characteristic peaks of sodium manganese phosphate begin to weaken significantly, and the purity of the material is significantly improved.

[0050] Application Examples 1 to 5 are used to assemble a button cell, as follows.

[0051] The cathode materials in the above Examples 1 to 4 and Comparative Example 1 were respectively assembled into sodium-ion batteries. The assembly of the sodium-ion batteries adopted the assembly steps of standardized button cells, and the steps were as follows: The cathode materials, acetylene black, and polyvinylidene fluoride (PVDF) prepared in Examples 1 to 4 or Comparative Example 1 were weighed according to a mass ratio of 8:1:1, and N-methylpyrrolidone (NMP) was used as a solvent to grind them into a uniform slurry in a ball mill. Then, the slurry was evenly coated on aluminum foil with an automatic coater and dried at 80 °C for 12 h in a vacuum environment. Then, it was cut into pieces, and this piece was used as the cathode; then, a sodium sheet was used as the anode, glass fiber (Whatman GF / C) was used as the separator, and the electrolyte was 1M NaClO4 / EC:DEC (v:v = 1:1, Vol% with 5% FEC). The CR2025 type button cell was assembled in an argon atmosphere glove box with water and oxygen values both lower than 0.01 ppm.

[0052] The first charge-discharge curve of the sodium-ion battery corresponding to Application Example 2 is as Figure 3 shown. The first charge-discharge curve of the sodium-ion battery corresponding to Application Example 4 is as Figure 4 shown. The first charge-discharge curve of the sodium-ion battery corresponding to Application Example 5 is as Figure 2 shown. The specific capacities of the sodium-ion batteries corresponding to Application Examples 1 to 5 are shown in Table 1.

[0053] Table 1

[0054] Battery Positive electrode material <![CDATA[Specific capacity / mAh g -1 > Application Example 1 Example 1 108.45 Application Example 2 Example 2 114.99 Application Example 3 Example 3 112.5 Application Example 4 Example 4 109.57 Application Example 5 Comparative Example 1 104.37

[0055] Combining Table 1 with Figure 2 、 Figure 3 、 Figure 4 , we can find that for Comparative Example 1 synthesized according to the normal stoichiometric ratio, the first-cycle discharge specific capacity of the sodium-ion battery corresponding to Application Example 5 is only 104.37 mAh / g; while through the technical solution of the present application, by reducing the amounts of iron and manganese, the first-cycle discharge specific capacities of the batteries corresponding to Application Example 2 and Application Example 4 of Example 2 and Example 4 can reach 114.99 mAh / g and 109.57 mAh / g respectively; it is at a leading level among similar materials, and the voltage hysteresis phenomenon is also improved to a certain extent, indicating the effectiveness of the iron-manganese co-defect of the technical solution of the present application.

[0056] Through Figure 5 we can see that the Na 4 (Fe) 1.5-X (Mn) 1.5-y (PO 4 ) 2 P 2 O 7The / C cathode material has a very good spherical morphology and a good ratio of large to small spheres, further demonstrating the industrial application value of the cathode material prepared by us.

[0057] The above are all preferred embodiments of this application. Without restricting the protection scope of this application accordingly, therefore, all equivalent changes made according to the structure, shape, and principle of this application shall be covered within the protection scope of this application.

Claims

1. A sodium ion battery positive electrode material, characterized in that: Na4(Fe) 1.5-X (Mn) 1.5-y The complex of (PO4)2P2O7 and C, where 0 <x<0.5,0<y<0.5。 2. The positive electrode material according to claim 1, characterized in that The C accounts for 1 to 5 wt %.

3. The positive electrode material according to claim 1, characterized in that The Na4(Fe) 1.5-X (Mn) 1.5-y In (PO4)2P2O7, x=y.

4. A method for preparing the positive electrode material according to claim 1, characterized in that: The following steps are involved: S1. Weigh the sodium source, iron source, phosphorus source, carbon source and manganese source respectively, add them into deionized water in turn, stir and disperse them to obtain a suspension, wherein the molar ratio of sodium, iron and manganese is controlled to be 4: (1.5-x): (1.5-y), 0 <x<0.5,0<y<0.5; S2, performing sand milling and nano-processing on the suspension prepared in S1, and then spray drying the suspension to obtain a precursor powder; S3. The precursor powder prepared in S2 is sintered in an inert atmosphere to obtain a positive electrode material.

5. The preparation method according to claim 4, characterized in that: The sodium source is one or more of disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium phosphate, sodium carbonate, sodium bicarbonate, sodium pyrophosphate, sodium oxalate, and sodium acetate; And / or, the iron source is one or more of ferric nitrate, ferric phosphate, ferrous oxalate, ferric oxide, ferrosiric oxide, ferrous acetate, and ferric acetylacetonate; And / or, the phosphorus source is one or more of sodium dihydrogen phosphate, disodium hydrogen phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, sodium phosphate, sodium pyrophosphate, and phosphoric acid; and / or, the carbon source is one or more of citric acid, ascorbic acid, oxalic acid, stearic acid, glucose, agarose, sucrose, cellulose, and polyethylene glycol; And / or, the manganese source is one or more of manganese nitrate, manganese acetate, manganese oxalate, manganese sulfate, manganese chloride, and manganese trioxide.

6. The preparation method according to claim 4, characterized in that: In S1, the stirring method of the stirring and dispersing is one of mechanical stirring and magnetic stirring; the stirring speed is 100 rpm to 1200 rpm, the stirring temperature is 10 to 60° C., and the stirring time is 1 to 10 h.

7. The preparation method according to claim 4, characterized in that: In S2, the spray drying process is as follows: inlet temperature is 200-260°C, outlet temperature is 90-110°C, fan speed is 90%, and peristaltic pump speed is 40%.

8. The preparation method according to claim 4, characterized in that: In S3, the inert atmosphere is one of argon, nitrogen, and a hydrogen-argon mixed gas; the sintering method of the sintering treatment is a two-stage sintering, the first stage is kept at 300-350°C for 3-6 hours, the second stage is kept at 500-600°C for 10-15 hours, and the heating rate from the first stage temperature to the second stage temperature is 1-5°C / min.

9. A sodium ion battery, characterized in that: Comprising the positive electrode material according to claim 1.

10. Application of the sodium ion battery described in claim 9 in the field of energy storage technology.

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