A dual-anion sodium-ion battery cathode material, a preparation method and application thereof

Abstract

The application relates to a double anion sodium ion battery positive electrode material and a preparation method and application thereof, and belongs to the technical field of sodium ion batteries. p Cu x Fe y Mn z M q O (2‑α‑β) (SO4) β F α , wherein M is a doping element other than Cu, Fe and Mn; 0.61 < p <= 0.78, 0.22 <= x <= 0.33, 0.10 <= y <= 0.12, 0.45 <= z <= 0.78, 0.08 <= q <= 0.12, and x + y + z + q = 1; 0 < alpha <= 0.1; 0 < beta <= 0.05, the values of p, x, y, z, q, alpha and beta satisfy the charge balance of the chemical formula. The double anion sodium ion battery positive electrode material has strong electronegativity, and the two kinds of anions form a more stable structure with cations in the material, and the sodium ion free distance is shortened, and the structural stability is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sodium ion batteries, and particularly relates to a double-anion sodium ion battery positive electrode material and a preparation method and application thereof. BACKGROUND

[0002] With the progress of human society and the development of science and technology, the demand for energy is also increasing. Fossil energy plays a huge role in it, but it is relatively polluting. Since the end of the last century, people have gradually focused on clean energy, and solar energy, wind energy, tidal energy and nuclear energy have gradually increased their share in the use of energy. At the same time, the battery industry is also constantly improving, from alkaline batteries to lead-acid batteries, and then to lithium ion batteries. The energy density of the battery is getting higher and higher, the performance is getting better and better, and it is more friendly to the environment.

[0003] At present, more lithium ion batteries are on the market, which have excellent performance, but their shortcomings are also relatively obvious. First, the content of lithium element in the earth's crust is low, only 0.0065%. Second, lithium ore is concentrated in South America, and most of our country relies on imports, which is not conducive to the development of lithium resource industry on the one hand, and is likely to be subject to international situation on the other hand. Under this condition, there is an urgent need for a material that can replace lithium ion batteries. Sodium ion batteries have been researched since the last century, and sodium resources are widely distributed and have considerable reserves, but they have been shelved due to low energy density, unstable structure and other problems.

[0004] Sodium ion batteries mainly focus on sodium ion battery positive electrode materials. In recent years, layered oxides, polyanion compounds and prussian blue materials have been studied. Among them, layered oxides are suitable for industrialization due to their high energy density and relatively simple process, and are intensively studied. However, due to the unstable structure of layered oxides, the problem of poor cycle is difficult to solve, and the practical application still has great difficulty. Generally speaking, there are two modification methods, namely doping and coating. The doping element enters the bulk phase, replaces some elements in the lattice, and hinders the structural distortion. The coating element is on the surface of the material, which isolates the positive electrode material from air, water and electrolyte, effectively inhibiting the cycle deterioration. Both methods have certain effect on improving performance, but there is still a lot of room for improvement. We improve the electrical conductivity, reduce the polarization voltage, remove impurity phases, inhibit irreversible phase transition, and improve the structural stability by introducing anions. SUMMARY

[0005] Therefore, the technical problem to be solved by the present application is to overcome the poor cycle stability of the layered oxide sodium ion battery positive electrode material in the prior art.

[0006] To solve the above technical problems, the present application provides a double-anion sodium ion battery positive electrode material and a preparation method and application thereof.

[0007] The first object of the present application is to provide a double anion sodium ion battery cathode material, which comprises at least one compound of formula Na p Cu x Fe y Mn z M q O (2-α-β) (SO4) β F α , wherein M is a doping element other than Cu, Fe and Mn; 0.61

[0008] In an embodiment of the present application, M is selected from one or more of Mg, Ca, Sr, Sn, Zn, Y, Nb, Sb, Bi, Cd, Mo, Cr and Co.

[0009] The second object of the present application is to provide a preparation method of the double anion sodium ion battery cathode material, which comprises the following steps,

[0010] (1) mixing a copper source, an iron source, a manganese source and an M source, and obtaining an M-doped precursor by ball milling and calcination;

[0011] (2) mixing the M-doped precursor of step (1) with a sulfuric acid source, a fluorine source and a sodium source, and obtaining the double anion sodium ion battery cathode material by ball milling and calcination.

[0012] In an embodiment of the present application, in step (1), the copper source, the iron source and the manganese source are independently selected from one or more of oxides, carbonates, acetates and hydroxides of the corresponding elements.

[0013] The M source is selected from one or more of oxides, carbonates, fluorides, hydroxides, acetates and sulfates.

[0014] In an embodiment of the present application, in step (1), the calcination temperature is 350-500 DEG C, and the time is 3-6 h.

[0015] In an embodiment of the present application, in step (1), the ball milling time is 8-12 h, the rotation speed is 400-600 r / min, and the material-to-ball ratio is 10 g / ball.

[0016] In an embodiment of the present application, in step (2), the source of sulfuric acid is selected from one or more of sodium sulfate, magnesium sulfate, zinc sulfate, aluminum sulfate and calcium sulfate.

[0017] The source of fluorine is selected from one or more of sodium fluoride, magnesium fluoride, calcium fluoride and aluminum fluoride.

[0018] The source of sodium is selected from one or more of sodium fluoride, sodium carbonate, sodium hydroxide, sodium oxalate and sodium sulfate.

[0019] In an embodiment of the present application, in step (2), the temperature of calcination is 950-1050℃, and the time is 8-12h.

[0020] In an embodiment of the present application, in step (2), the time of ball milling is 3-5h, the rotation speed is 200-400r / min, and the ratio of material to ball is 10g / ball.

[0021] A third object of the present application is to provide a sodium-ion battery positive electrode, comprising the said double anion sodium-ion battery positive electrode material, a conductive agent and a binder in mass parts; the amount of the conductive agent is ≤10wt%; the amount of the binder is ≤10wt%.

[0022] Further, the amount of the conductive agent is 0.01wt%-10wt%, 1wt%-10wt%, 2wt%-10wt%, 3wt%-10wt%, 4wt%-10wt%, 5wt%-10wt%, 6wt%-10wt%, 7wt%-10wt%, 8wt%-10wt%, 9wt%-10wt%. 0.01wt%, 0.05wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt%, 10wt%; or any concentration value between any two numerical values.

[0023] Further, the amount of the binder is 0.01wt% to 10wt%, 1wt% to 10wt%, 2wt% to 10wt%, 3wt% to 10wt%, 4wt% to 10wt%, 5wt% to 10wt%, 6wt% to 10wt%, 7wt% to 10wt%, 8wt% to 10wt%, 9wt% to 10wt%. 0.01wt%, 0.05wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt%, 10wt%; or any concentration value between any two numerical values.

[0024] In one embodiment of the present application, the conductive agent is selected from one or more of carbon nanotubes, acetylene black, conductive carbon black, conductive graphite, carbon fibers and graphene;

[0025] The binder is selected from one or more of polyolefin-based, fluorine-containing resin, polypropylene resin and rubber.

[0026] Further, the binder is selected from one or more of polyvinylidene fluoride, styrene rubber, nitrile rubber, styrene butadiene rubber (SBR), polyacrylamide (PAA), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylonitrile (PAN), polyimide (PI), butadiene rubber, modified butadiene rubber, carboxyl-modified styrene butadiene rubber and modified polyorganosiloxane-based polymer.

[0027] A fourth object of the present application is to provide a sodium ion battery comprising the sodium ion battery cathode.

[0028] The technical solution of the present application has the following advantages compared with the prior art:

[0029] (1) The dual anion sodium ion battery cathode material of the present application utilizes fluorine ions to improve electrical conductivity, reduce polarization voltage, and at the same time remove impurity phases, thereby improving structural stability. On the other hand, fluorine ions combine with oxygen to form stable covalent bonds, inhibit unfavorable P2-O2 phase transition, maintain structural stability, and effectively improve capacity retention rate.

[0030] (2) The dual anion sodium ion battery cathode material of the present application uses sulfate as an anion, and sulfate undergoes sp3 hybridization, resulting in a more stable structure.

[0031] (3) The double anion sodium ion battery positive electrode material described in the application takes sulfate and fluoride as anions, both of which have strong electronegativity and form a more stable structure with the cations in the material, at the same time shortening the free distance of sodium ions and improving the structural stability.

[0032] (4) The double anion sodium ion battery positive electrode material described in the application has excellent rate performance and good cycle performance, and is relatively simple to produce, suitable for industrialized production. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to make the content of the application more easily understood, the application will be further described in detail below according to specific embodiments of the application and in conjunction with the drawings, in which:

[0034] Figure 1 The XRD comparison chart of the sodium ion battery positive electrode materials of Example 1 and Comparative Example 1 of the application.

[0035] Figure 2 The pH change over time comparison chart of the sodium ion battery positive electrode materials of Example 1 and Comparative Example 1 of the application.

[0036] Figure 3 The cycle performance comparison chart of the sodium ion battery positive electrode materials of Example 1 and Comparative Example 1 of the application.

[0037] Figure 4 The cycle performance comparison chart of the sodium ion battery positive electrode materials of Example 2 and Comparative Example 2 of the application.

[0038] Figure 5 The cycle performance comparison chart of the sodium ion battery positive electrode materials of Example 3 and Comparative Example 3 of the application. DETAILED DESCRIPTION

[0039] The application will be further described below in conjunction with the drawings and specific embodiments, so that those skilled in the art can better understand the application and implement it, but the embodiments are not limiting the application.

[0040] In the application, unless otherwise specified, the ball-to-material ratio in the ball milling process in the examples is 10g / ball.

[0041] Example 1

[0042] A double anion sodium ion battery positive electrode material and a preparation method thereof, specifically comprising the following steps:

[0043] Weigh 39.773g of copper oxide (CuO), 99.108g of manganese dioxide (MnO2), 31.938g of iron oxide (Fe2O3), 13.025g of zinc oxide (ZnO), and place them in a ball mill tank. The speed of the ball mill is 600r / min, and high-speed mixing is carried out for 10h. Then, calcination is carried out at 500℃ for 6h. After cooling and sieving, a Zn-doped copper-iron-manganese precursor is obtained.

[0044] Weigh 90.017g of the Zn-doped copper-iron-manganese precursor, 35.506g of sodium carbonate (Na2CO3), 1.421g of sodium sulfate (Na2SO4), and 0.420g of sodium fluoride (NaF), and place them in a ball mill tank. The speed of the ball mill is 300r / min, and high-speed mixing is carried out for 3h. Then, calcination is carried out at 1020℃ for 9h. After cooling and sieving, a structure-stable bi-anion sodium-ion battery positive electrode material is finally obtained.

[0045] Example 2

[0046] A bi-anion sodium-ion battery positive electrode material and a preparation method thereof, specifically comprising the following steps:

[0047] Weigh 39.733g of copper oxide (CuO), 95.631g of manganese dioxide (MnO2), 31.938g of iron oxide (Fe2O3), and 16.282g of zinc oxide (ZnO), and place them in a ball mill tank. The speed of the ball mill is 500r / min, and high-speed mixing is carried out for 8h. Then, calcination is carried out at 500℃ for 4h. After cooling and sieving, a Zn-doped copper-iron-manganese precursor is obtained.

[0048] Weigh 90.227g of the Zn-doped copper-iron-manganese precursor, 35.506g of sodium carbonate (Na2CO3), 2.842g of sodium sulfate (Na2SO4), and 0.820g of sodium fluoride (NaF), and place them in a ball mill tank. The speed of the ball mill is 300r / min, and high-speed mixing is carried out for 3h. Then, calcination is carried out at 1000℃ for 10h. After cooling and sieving, a structure-stable bi-anion sodium-ion battery positive electrode material is finally obtained.

[0049] Example 3

[0050] A bi-anion sodium-ion battery positive electrode material and a preparation method thereof, specifically comprising the following steps:

[0051] Weigh 42.955g of copper oxide (CuO), 90.414g of manganese dioxide (MnO2), 35.132g of iron oxide (Fe2O3), and 8.061g of magnesium oxide (MgO), and place them in a ball mill tank. The speed of the ball mill is 450r / min, and high-speed mixing is carried out for 10h. Then, calcination is carried out at 480℃ for 6h. After cooling and sieving, a Mg-doped copper-iron-manganese precursor is obtained.

[0052] Weigh 86.298g Mg-doped copper iron manganese precursor, 35.506g sodium carbonate (Na2CO3), 1.204g magnesium sulfate (MgSO4), 0.781g calcium fluoride (CaF2), and place them in a ball mill jar. The ball mill speed is 300r / min, and high-speed mixing is carried out for 3h. After calcination at 980℃ for 12h, cooling and sieving, a structure-stable bi-anion sodium ion battery positive electrode material is finally obtained.

[0053] Example 4

[0054] A bi-anion sodium ion battery positive electrode material and a preparation method thereof, specifically comprising the following steps:

[0055] Weigh 42.955g copper oxide (CuO), 90.414g manganese dioxide (MnO2), 35.132g iron oxide (Fe2O3), and 30.142g tin oxide (SnO2), and place them in a ball mill jar. The ball mill speed is 500r / min, and high-speed mixing is carried out for 8h. Subsequently, calcination is carried out at 500℃ for 6h. After cooling and sieving, a Sn-doped copper iron manganese precursor is obtained.

[0056] Weigh 95.738g Sn-doped copper iron manganese precursor, 35.506g sodium carbonate (Na2CO3), 1.421g sodium sulfate (Na2SO4), and 0.781g calcium fluoride (CaF2), and place them in a ball mill jar. The ball mill speed is 300r / min, and high-speed mixing is carried out for 3h. After calcination at 980℃ for 12h, cooling and sieving, a structure-stable bi-anion sodium ion battery positive electrode material is finally obtained.

[0057] Comparative Example 1

[0058] Weigh 19.887g copper oxide (CuO), 49.553g manganese dioxide (MnO2), 15.970g iron oxide (Fe2O3), 6.513g zinc oxide (ZnO), and 35.506g sodium carbonate (Na2CO3), and place them in a ball mill jar. The ball mill speed is 300r / min, and high-speed mixing is carried out for 3h. After calcination at 1020℃ for 9h, cooling and sieving, a sodium ion battery positive electrode material is finally obtained.

[0059] Comparative Example 2

[0060] Weigh 19.887g copper oxide (CuO), 49.553g manganese dioxide (MnO2), 15.970g iron oxide (Fe2O3), 8.141g zinc oxide (ZnO), and 35.506g sodium carbonate (Na2CO3), and place them in a ball mill jar. The ball mill speed is 300r / min, and high-speed mixing is carried out for 3h. After calcination at 1000℃ for 10h, cooling and sieving, a sodium ion battery positive electrode material is finally obtained.

[0061] Comparative Example 3

[0062] Weigh 19.887g of copper oxide (CuO), 49.553g of manganese dioxide (MnO2), 15.970g of iron oxide (Fe2O3), 4.031g of magnesium oxide (MgO), and 35.132g of sodium carbonate (Na2CO3), place them in a ball mill jar, and mix at high speed for 3 hours at a ball mill speed of 300 r / min. Calcinate at 1000℃ for 10 hours, cool, and sieve to finally obtain the sodium-ion battery cathode material.

[0063] Test Example 1

[0064] XRD analysis was performed on the sodium-ion battery cathode materials prepared in Example 1 and Comparative Example 1, and the results are as follows: Figure 1 As shown, from Figure 1 It can be seen that the main structure of the sodium-ion battery cathode material prepared in Example 1 and Comparative Example 1 is a P2 type structure.

[0065] Test Example 2

[0066] The sodium-ion battery cathode materials prepared in Example 1 and Comparative Example 1 were exposed to air for 5, 9, 13, 17, and 21 days, and their pH values ​​were tested. The results are as follows: Figure 2 As shown, from Figure 2 It can be seen that the pH value of Example 2 changes less over time, and the rate of pH increase is significantly less than that of Comparative Example 2. This is because SO4 2- It has a strong attraction to cations, inhibits the precipitation of sodium ions, and reduces the absorption of water from the air, thus resulting in smaller changes in pH value.

[0067] Test Example 3

[0068] In an environment with 50% air humidity, coin cells were fabricated using the sodium-ion battery positive electrode materials obtained in Examples 1-3 and Comparative Examples 1-3, and their electrical performance was tested. The weight ratio of the electrode components was sodium-ion battery positive electrode material: conductive agent (acetylene black): binder (PVDF) = 80:10:10; the negative electrode used was a sodium sheet. The cycle performance of the coin cells was as follows: Figures 3-5 As shown. From Figures 3-5 It can be seen that the cycles of Examples 1-3 are superior to those of Comparative Examples 1-3, due to the doping with SO4. 2- Afterwards, it enters the bulk phase, where S occupies some of the transition metal sites, SO4 2- The S-type molecule undergoes sp3 hybridization, making it relatively stable and playing a crucial role in structural stability. F - Doping replaces some oxygen sites in the structure, forming stable covalent bonds with oxygen, while suppressing the unfavorable P2-O2 phase transition and improving cycle stability.

[0069] Obviously, the above embodiments are merely example for clearly illustrating, and are not limitation to the embodiments. For ordinary skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, all the embodiments need not and can not be exhausted. The obvious changes or variations derived therefrom are still within the scope of the present invention.

Claims

1. A dual anion sodium-ion battery cathode material, characterized in that, The double anion sodium ion battery cathode material comprises at least one compound of formula Na p Cu x Fe y Mn z M q O (2-α-β) (SO4) β F α , wherein the M is selected from one or more of Mg, Ca, Sr, Sn, Zn, Y, Nb, Sb, Bi, Cd, Mo, Cr and Co; 0.61 0.08≤q≤0.12, and x+y+z+q=1; 0<α≤0.1; 0<β≤0.05, the values of p, x, y, z, q, α and β satisfy the charge balance of the chemical formula.

2. The method of producing a bi-anionic sodium-ion battery cathode material of claim 1, characterized in that, The method comprises the following steps, (1) mixing a copper source, an iron source, a manganese source and an M source, ball-milling and calcining to obtain an M-doped precursor; (2) mixing the M-doped precursor of step (1) with a sulfuric acid source, a fluorine source and a sodium source, ball-milling and calcining to obtain the dual anion sodium ion battery cathode material.

3. The method of claim 2, wherein the method further comprises the step of: In step (1), the copper source, the iron source and the manganese source are independently selected from one or more of oxides, carbonates, acetates and hydroxides of the corresponding elements; The M source is selected from one or more of oxides, carbonates, fluorides, hydroxides, acetates and sulfates.

4. The method of claim 2, wherein the method further comprises the step of: In step (1), the calcination temperature is 350-500°C, and the time is 3-6h.

5. The dual anion sodium-ion battery cathode material of claim 2, wherein, In step (2), the sulfuric acid source is selected from one or more of sodium sulfate, magnesium sulfate, zinc sulfate, aluminum sulfate and calcium sulfate; The fluorine source is selected from one or more of sodium fluoride, magnesium fluoride, calcium fluoride and aluminum fluoride; The sodium source is selected from one or more of sodium fluoride, sodium carbonate, sodium hydroxide, sodium oxalate and sodium sulfate.

6. The method of claim 2, wherein the method further comprises the step of: In step (2), the calcination temperature is 950-1050°C, and the time is 8-12h.

7. A sodium-ion battery cathode, characterized in that, The dual anion sodium ion battery cathode material of claim 1, a conductive agent and a binder are included in mass parts; the amount of the conductive agent is ≤10wt%; the amount of the binder is ≤10wt%.

8. The sodium-ion battery cathode of claim 7, wherein, The conductive agent is selected from one or more of carbon nanotubes, acetylene black, conductive carbon black, conductive graphite, carbon fibers and graphene; The binder is selected from one or more of polyolefins, fluorine-containing resins, polypropylene resins and rubbers.

9. A sodium-ion battery, characterized in that, The sodium ion battery cathode of claim 7 or 8.

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