An oxide, a method for preparing the same, and an application thereof

Abstract

The application discloses an oxide, a preparation method and application of the oxide, and has a chemical formula of Na 0.7 Fe X Mn 1‑X O 2‑ Y F Y ; the X is 0.1; the Y is 0.1; and the oxide is layered. The material has a simple preparation process, a simplified raw material composition and is suitable for mass production. Meanwhile, the layered metal oxide material is applied to a sodium ion battery positive electrode and can exhibit excellent rate capability and good stability.

Description

Technical Field

[0001] This invention relates to an oxide, its preparation method, and its application, belonging to the field of sodium-ion batteries. Background Technology

[0002] With the continuous development of China's energy industry, the country's energy structure and quality are constantly improving, and energy demand is shifting from traditional non-renewable energy sources such as coal to more environmentally friendly clean energy. The diverse, multi-faceted, safe, and low-carbon characteristics of this new stage of energy development are leading the world's energy development. Batteries, as convenient energy storage devices that meet these characteristics, are also experiencing continuous expansion. Among the many types of energy storage devices, lithium-ion batteries are currently widely researched and applied in various electronic devices. However, the increasing demand for lithium resources has led to a continuous increase in the cost of lithium batteries, which limits their future development. Compared to lithium-ion batteries, sodium, due to its abundant natural reserves and similar physicochemical properties to lithium, makes sodium-ion batteries a potential next-generation energy storage device to replace lithium-ion batteries.

[0003] Sodium ions have a larger ionic radius and migrate more slowly than lithium ions. Sodium-ion batteries consist of positive and negative electrode materials, a separator, and an electrolyte. The performance of the positive electrode material plays a crucial role in the safety, power density, and energy density of sodium-ion batteries. Even now, the performance of the positive electrode material remains a key technology limiting the development of sodium-ion battery technology. To promote the large-scale application of sodium-ion batteries, developing high-specific-capacity positive electrode materials is an important current research direction. X MnO2 cathode material possesses advantages such as high specific capacity, low cost, and non-toxicity, making it a relatively ideal cathode material for sodium-ion batteries. However, sodium manganate cathode material suffers from poor stability, resulting in poor capacity utilization and rate performance. Therefore, to better promote the application of sodium manganate in sodium-ion battery cathodes, it needs to be optimized and further processed. Summary of the Invention

[0004] According to one aspect of this application, an oxide is provided, the oxide having the chemical formula Na. 0.7 Fe X Mn 1- X O 2-Y F Y ;

[0005] X is 0.01 to 0.4;

[0006] The value of Y is 0.01 to 0.4;

[0007] The oxide is layered.

[0008] According to another aspect of this application, a method for preparing the above-mentioned oxide is provided.

[0009] Includes the following steps:

[0010] 1) Mix raw materials containing sodium and manganese sources, ball mill I, calcine I, to obtain intermediate products;

[0011] 2) The intermediate product obtained in 1) is mixed with an iron source and a fluorine source, ball-milled (II), and calcined (II) to obtain the oxide.

[0012] The sodium source is selected from at least one of sodium bicarbonate, sodium carbonate, or sodium nitrate.

[0013] The manganese source is selected from at least one of manganese dioxide, manganese trioxide, or manganese tetroxide.

[0014] Optionally, the molar ratio of the sodium source to the manganese source is 1:0.8 to 1.2.

[0015] Wherein, the molar amount of the sodium source is expressed as the molar amount of sodium element therein;

[0016] The molar amount of the manganese source is expressed as the molar amount of manganese element therein.

[0017] Optionally, the molar ratio of the sodium source to the manganese source is 1:0.8, 1:0.9, 1:1.0, 1:1.1, or 1:1.2.

[0018] The rotational speed of the ball mill I is 200–800 rpm.

[0019] Optionally, the rotational speed of the ball mill I is any value among 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, and 800 rpm, or a range between any two.

[0020] The ball milling time is 6 to 12 hours.

[0021] Optionally, the ball milling time I is any value among 6h, 7h, 8h, 9h, 10h, 11h, and 12h, or a range between any two.

[0022] The calcination temperature is 500–1000°C.

[0023] Optionally, the calcination temperature I is any value among 500℃, 600℃, 700℃, 800℃, 900℃, and 1000℃, or a range between any two.

[0024] The calcination time is 4 to 12 hours.

[0025] Optionally, the calcination time I is any value among 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, and 12h, or a range between any two.

[0026] The iron source is selected from at least one of ferrous sulfate heptahydrate, ferric chloride, or ferric acetylacetone.

[0027] The fluorine source is selected from at least one of sodium fluoride, ammonium fluoride, or ammonium hydrofluoride.

[0028] Optionally, the molar ratio of the iron source to the fluorine source is 0.8-1:1-1.8.

[0029] Optionally, the molar ratio of the iron source to the fluorine source is 0.8:1, 0.8:1.2, 0.8:1.4, 0.8:1.6, 0.8:1.8, 0.9:1, 0.9:1.2, 0.9:1.4, 0.9:1.6, 0.9:1.8, 1:1, 1:1.2, 1:1.4, 1:1.6, or 1:1.8.

[0030] The molar amount of the iron source is measured by the number of moles of iron element therein;

[0031] The molar amount of the fluorine source is expressed as the number of moles of fluorine element therein.

[0032] Optionally, the molar ratio of the intermediate product to the iron source is 1:0.1 to 0.4.

[0033] Optionally, the molar ratio of the intermediate product to the iron source is 1:0.1, 1:0.2, 1:0.3, or 1:0.4.

[0034] The rotational speed of the ball mill II is 200–800 rpm.

[0035] Optionally, the rotational speed of the ball mill II is any value among 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, and 800 rpm, or a range between any two.

[0036] The ball milling time for the second stage is 6 to 12 hours.

[0037] Optionally, the ball milling time II is any value among 6h, 7h, 8h, 9h, 10h, 11h, and 12h, or a range between any two.

[0038] The calcination temperature II is 600–1000 °C.

[0039] Optionally, the calcination temperature II is any value among 600℃, 700℃, 800℃, 900℃, and 1000℃, or a range between any two.

[0040] The calcination time II is 12–24 h.

[0041] Optionally, the calcination time II is any value among 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, and 24h, or a range between any two.

[0042] Furthermore, it includes the following steps:

[0043] a) The compound containing sodium and manganese sources is ball-milled thoroughly and mixed evenly to obtain a powder;

[0044] b) Calcining the powder yields sodium manganate;

[0045] c) After grinding the powder, a compound containing an iron source and a fluorine source is added, and the mixture is calcined to obtain the oxide.

[0046] According to another aspect of this application, a positive electrode material is provided, wherein the positive electrode material contains the oxide described above or the oxide prepared by the preparation method described above.

[0047] According to another aspect of this application, an application of the above-described cathode material in a sodium-ion battery is provided.

[0048] The beneficial effects that this application can produce include:

[0049] The preparation method provided in this application is simple, the raw material composition is simple, and the prepared Na 0.7 Fe X Mn 1-X O 2-Y F Y It has excellent cycle performance and rate performance.

[0050] Na of this application 0.7 Fe X Mn 1-X O 2-Y F Y The preparation method is low-cost, has good economic benefits, is conducive to industrial application, is easy to scale up production, and has a good application prospect in sodium-ion batteries. Attached Figure Description

[0051] Figure 1 Na prepared in Example 1 of this invention 0.7 Fe 0.1 Mn 0.9 O 1.9 F 0.1 Scanning electron microscope image.

[0052] Figure 2 Na prepared in Example 1 of this invention 0.7 Fe 0.1 Mn 0.9 O 1.9 F 0.1 A magnified view of the scanning electron microscope image.

[0053] Figure 3 Na prepared in Example 1 of this invention 0.7 Fe 0.1 Mn 0.9 O 1.9 F 0.1 XRD pattern.

[0054] Figure 4 Na prepared in Example 1 of this invention 0.7 Fe 0.1 Mn 0.9 O 1.9 F 0.1 Half-cell at 200mA g -1 Cyclic performance diagrams at current densities, with voltage ranges from 1.5 to 4.2 V.

[0055] Figure 5 Na prepared in Example 1 of this invention 0.7 Fe 0.1 Mn 0.9 O 1.9 F 0.1 Rate cycling curve of a half-cell, with a voltage range of 1.5 to 4.2V. Detailed Implementation

[0056] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0057] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0058] The analysis method in the embodiments of this application is as follows:

[0059] The morphology of the samples was analyzed and tested using a scanning electron microscope (SEM, Quanta 200F).

[0060] The crystal phase composition of the sample was analyzed and tested using an X-ray diffractometer (XRD, SmartLab).

[0061] Constant current charge / discharge tests were conducted using the LAND CT2001A battery system (Wuhan Landian Electronics Co., Ltd.).

[0062] Example 1

[0063] 0.05 mol of sodium bicarbonate and 0.06 mol of manganese trioxide were weighed into a ball mill jar and ball-milled at 500 rpm for 12 h. Then, the mixture was heat-treated in a muffle furnace to 800 °C and held for 10 h. Next, an appropriate amount of the obtained material was mixed with 0.02 mol of ferric acetylacetone and 0.12 mol of sodium fluoride, and ball-milled at 500 rpm for 12 h. Then, the mixture was heat-treated in a muffle furnace to 800 °C and held for 12 h. This yielded iron-fluorine co-doped sodium manganate product Na. 0.7 Fe 0.1 Mn 0.9 O 1.9 F 0.1 .

[0064] Figure 1 Na prepared in Example 1 of this invention 0.7 Fe 0.1 Mn 0.9 O 1.9 F 0.1 Scanning electron microscope image.

[0065] Figure 2 Na prepared in Example 1 of this invention 0.7 Fe 0.1 Mn 0.9 O 1.9 F 0.1 A magnified view of the scanning electron microscope image.

[0066] Figure 3 Na prepared in Example 1 of this invention 0.7 Fe 0.1 Mn 0.9 O 1.9 F 0.1 XRD pattern.

[0067] Through append Figure 1 The scanning electron microscope (SEM, 10 μm) image shows that the prepared Na 0.7 Fe 0.1 Mn 0.9 O 1.9 F 0.1 It has a rod-like structure; attached Figure 2 The prepared Na2O4 was observed in the scanning electron microscope (SEM, 5 μm) image. 0.7 Fe 0.1 Mn 0.9 O 1.9 F 0.1 The surface has stripes. (This is achieved through attaching...) Figure 3 The X-ray diffraction (XRD) pattern shows that the prepared Na 0.7 Fe 0.1 Mn 0.9 O 1.9 F0.1 Consistent with PDF card 27-0751.

[0068] The iron-fluorine co-doped sodium manganate Na prepared in this embodiment 0.7 Fe 0.1 Mn 0.9 O 1.9 F 0.1 After grinding the conductive agent (ECP) and binder (PVDF) evenly at a mass ratio of 8:1:1, an appropriate amount of N-methylpyrrolidone was added and coated onto carbon-coated aluminum foil to a thickness of 200 μm. The coated aluminum foil was then placed in a 100°C oven and vacuum-dried for 6 hours, and then punched into circular electrode sheets with a diameter of 12 mm for assembling No. 2016 batteries. 0.7 Fe 0.1 Mn 0.9 O 1.9 F 0.1 As the positive electrode of a sodium-ion battery, it forms a half-cell with a sodium metal negative electrode. The electrolyte is a 1M NaClO4 solution of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC), containing 2% fluorinated ethylene carbonate (FEC). The separator is a glass fiber membrane. The prepared iron-fluorine co-doped sodium manganate Na... 0.7 Fe 0.1 Mn 0.9 O 1.9 F 0.1 Electrochemical performance was tested.

[0069] Figure 4 Na prepared in Example 1 of this invention 0.7 Fe 0.1 Mn 0.9 O 1.9 F 0.1 Half-cell at 200mA g -1 Cyclic performance diagrams at current densities, with voltage ranges from 1.5 to 4.2 V.

[0070] Figure 5 Na prepared in Example 1 of this invention 0.7 Fe 0.1 Mn 0.9 O 1.9 F 0.1 Rate cycling curve of a half-cell, with a voltage range of 1.5 to 4.2V.

[0071] Through append Figure 4 It can be seen that at 200mA g -1 At a current density of 179 mAh g, the prepared iron-fluorine co-doped sodium manganate exhibited a discharge specific capacity of 179 mAh g. -1 After 150 cycles, the capacity still reaches 137mAh g. -1The capacity retention rate reached 76.5%, exhibiting excellent cycle stability. Rate testing was performed on the prepared iron-fluorine co-doped sodium manganate half-cell. Figure 5 It can also be seen that, at battery capacities of 0.1, 0.2, 0.5, 1, 2, 4, and 5C, the average discharge specific capacities of the batteries are 207, 166, 141, 128, 118, 107, and 101 mAh g, respectively. -1 And when the current density drops to 20 mA g -1 At that time, the specific capacity can recover to 191mAhg -1 The prepared iron-fluorine co-doped sodium manganate exhibits excellent rate performance.

[0072] Example 2

[0073] 0.03 mol of sodium carbonate and 0.024 mol of manganese tetroxide were weighed into a ball mill jar and ball-milled at 500 rpm for 12 h. Then, the mixture was heat-treated in a muffle furnace to 800 °C and held for 6 h. An appropriate amount of the resulting material was then mixed with 0.05 mol of ferric chloride and 0.05 mol of ammonium hydrofluoride and ball-milled at 500 rpm for 12 h. This was followed by heat treatment in a muffle furnace to 900 °C and held for 12 h. The resulting iron-fluorine co-doped sodium manganate product was obtained. The SEM, XRD, and electrical properties of the product prepared in Example 2 were similar to those of the sample prepared in Example 1.

[0074] Example 3

[0075] 0.1 mol of sodium carbonate and 0.1 mol of manganese tetroxide were weighed into a ball mill jar and ball-milled at 500 rpm for 12 h. Then, the mixture was heat-treated in a muffle furnace to 600 °C and held for 6 h. An appropriate amount of the obtained material was then added to 1 mol of ferrous sulfate heptahydrate and 1.2 mol of ammonium fluoride, and ball-milled at 500 rpm for 12 h. This was followed by heat treatment in a muffle furnace to 600 °C and held for 12 h. The resulting product was iron-fluorine co-doped sodium manganate. The SEM, XRD, and electrical properties of the product prepared in Example 3 were similar to those of the sample prepared in Example 1.

[0076] Example 4

[0077] 0.1 mol of sodium bicarbonate and 0.08 mol of manganese dioxide were weighed into a ball mill jar and ball-milled at 500 rpm for 12 h. Then, the mixture was heat-treated in a muffle furnace to 800 °C and held for 6 h. An appropriate amount of the resulting material was then mixed with 1 mol of ferric chloride and 1.2 mol of ammonium fluoride and ball-milled at 500 rpm for 12 h. This was followed by heat treatment in a muffle furnace to 1000 °C and held for 12 h. The resulting iron-fluorine co-doped sodium manganate product was obtained. The SEM, XRD, and electrical properties of the product prepared in Example 4 were similar to those of the sample prepared in Example 1.

[0078] Example 5

[0079] 0.8 mol of sodium nitrate and 0.1 mol of manganese dioxide were weighed into a ball mill jar and ball-milled at 500 rpm for 12 h. Then, the mixture was heat-treated in a muffle furnace to 1000 °C and held for 6 h. An appropriate amount of the resulting material was then mixed with 0.8 mol of ferric chloride and 1 mol of sodium fluoride and ball-milled at 500 rpm for 12 h. This was followed by heat treatment in a muffle furnace to 800 °C and held for 12 h. The resulting iron-fluorine co-doped sodium manganate product was obtained. The SEM, XRD, and electrical properties of the product prepared in Example 5 were similar to those of the sample prepared in Example 1.

[0080] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method of producing an oxide, characterized by, Includes the following steps: 1) Mix raw materials containing sodium and manganese sources, ball mill I, calcine I, to obtain intermediate products; 2) The intermediate product obtained in 1) is mixed with an iron source and a fluorine source, ball-milled (II), and calcined (II) to obtain the oxide; The molar ratio of the sodium source to the manganese source is 1:0.8~1.2; The molar amount of the sodium source is expressed as the molar amount of sodium element therein; The molar amount of the manganese source is expressed as the molar amount of manganese element therein. The molar amount of the fluorine source is expressed as the number of moles of fluorine element therein; The molar ratio of the intermediate product to the iron source is 1:0.1~0.4; The calcination temperature I is 500~1000℃; The calcination time for step I is 4-12 hours; The calcination temperature II is 600~1000℃; The calcination time for II is 12-24 hours; The chemical formula of the oxide is Na 0.7 Fe X Mn 1-X O 2-Y F Y ; X is 0.01~0.4; The value of Y is 0.01 to 0.4; The oxide has a layered structure; The oxide has a rod-shaped morphology.

2. The preparation method according to claim 1, characterized in that, The sodium source is selected from at least one of sodium bicarbonate, sodium carbonate, or sodium nitrate. The manganese source is selected from at least one of manganese dioxide, manganese trioxide, or manganese tetroxide.

3. The preparation method according to claim 1, characterized in that, The rotational speed of the ball mill I is 200~800 rpm; The ball milling time is 6-12 hours.

4. The preparation method according to claim 1, characterized in that, The iron source is selected from at least one of ferrous sulfate heptahydrate, ferric chloride, or ferric acetylacetone. The fluorine source is selected from at least one of sodium fluoride, ammonium fluoride, or ammonium hydrofluoride.

5. The preparation method according to claim 1, characterized in that, The rotational speed of the ball mill II is 200~800 rpm; The ball milling time for the second stage is 6 to 12 hours.

6. An oxide prepared by any one of claims 1 to 5, characterized in that, The chemical formula of the oxide is Na 0.7 Fe X Mn 1-X O 2-Y F Y ; X is 0.01~0.4; The value of Y is 0.01 to 0.4; The oxide has a layered structure; The oxide has a rod-shaped morphology.

7. A positive electrode material, characterized in that, The cathode material contains an oxide prepared by the preparation method according to any one of claims 1 to 5 or an oxide according to claim 6.

8. The application of the cathode material according to claim 7 in a sodium-ion battery.

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