P2-type sodium electric layered oxide electrode material and preparation method thereof

Abstract

The application discloses a P2 type sodium electric layered oxide electrode material and a preparation method thereof, relates to the technical field of sodium ion batteries, and comprises the following steps: taking a sodium source, a nickel source, an iron source, a manganese source, a magnesium source and an aluminum source, mixing the sources, adding deionized water to jointly dissolve the sources through ultrasonic, stirring again, and obtaining a first solution; dissolving oxalic acid in deionized water to obtain a second solution; adding the second solution drop by drop into the first solution and stirring to obtain a third solution; heating and stirring the third solution; naturally cooling the third solution, taking out, filtering, and drying to obtain a precursor; calcining the precursor in an oxygen-free environment, naturally cooling the precursor, taking out, and grinding to obtain a raw material powder; and calcining the raw material powder in a high-temperature inert gas environment to obtain an electrode material. The preparation method can introduce oxygen vacancies by calcining in an oxygen-free environment, can embed more sodium ions, and can improve the specific capacity; and the electrode material has both capacity and cycle.

Description

A P2-type sodium-ion layered oxide electrode material and its preparation method Technical Field

[0001] This application relates to the field of sodium-ion battery technology, and in particular to a P2 type sodium-ion layered oxide electrode material and its preparation method. Background Technology

[0002] Sodium-ion batteries (SIBs) are considered a cost-effective option for grid-scale energy storage systems due to the abundant sodium reserves. However, the actual energy density and cycle stability of SIBs are insufficient to meet the needs of various application scenarios. To improve their energy density, the cathode material must be able to intercalate and deintercalate more sodium ions. Layered metal oxides (LMOs) are among the most promising candidate materials for SIBs due to their relatively high specific capacity, low cost, and ability to be used in lithium-ion ternary battery production lines. Currently, to pursue higher energy density, SIBs primarily use O3-type layered oxides as their cathodes.

[0003] While O3-type layered oxide materials exhibit high specific capacity, they undergo structural transformations during charge-discharge in the 2.0-4.0V range, from O3 to O'3 to P3 to P'3 and back to O3 phases. The significant changes in lattice parameters between these phases result in low cycle stability. In contrast, P2-type layered oxide materials show fewer phase transitions and smaller changes in lattice parameters during charge-discharge (charging: P2 phase transforms into O2 or OP4 / “Z” phase; discharging: P2 phase transforms into P'2 phase), exhibiting good cycle stability. However, their interlayer sodium content is only 0.67%, resulting in a lower specific capacity of only 110 mAh / g. Summary of the Invention

[0004] To address the issues of low interlayer sodium content and low specific capacity in existing P2-type layered oxide materials, this application provides a technical solution that aims to increase the sodium ion content embedded in the interlayers of P2-type layered oxides during the first discharge by sintering the precursor material in an oxygen-free environment to generate oxygen vacancies within the material, thereby improving the specific capacity of P2-type layered oxides.

[0005] Specifically, in order to achieve the above technical solution, in a first aspect, this application provides a method for preparing a P2-type sodium-ion layered oxide electrode material, comprising the following steps:

[0006] Sodium, nickel, iron, manganese, magnesium, and aluminum sources are mixed, deionized water is added, and the mixture is dissolved by ultrasound. The mixture is then stirred to obtain the first solution.

[0007] Oxalic acid was dissolved in deionized water to obtain a second solution;

[0008] The second solution is added dropwise to the first solution while stirring to obtain a third solution, which is then heated and stirred.

[0009] After the third solution has cooled naturally, it is removed, filtered, and dried to obtain the precursor.

[0010] The precursor is calcined in an oxygen-free environment. After the precursor cools naturally, it is taken out and ground to obtain raw material powder.

[0011] The raw material powder was calcined in a high-temperature inert gas environment to obtain P2 type sodium-ion layered oxide electrode material.

[0012] Preferably, the sodium source includes, but is not limited to, sodium-containing compounds such as sodium carbonate and sodium acetate; the nickel source includes, but is not limited to, nickel-containing compounds such as nickel nitrate, nickel sulfate, nickel chloride, and nickel acetate; the iron source includes, but is not limited to, ferric nitrate, ferric sulfate, ferric chloride, and ferric acetate; the manganese source includes, but is not limited to, manganese-containing compounds such as manganese acetate, manganese nitrate, manganese sulfate, potassium permanganate, and manganese chloride; the magnesium source includes, but is not limited to, magnesium-containing compounds such as magnesium acetate, magnesium nitrate, magnesium chloride, and magnesium sulfate; and the aluminum source includes, but is not limited to, aluminum-containing compounds such as aluminum nitrate, aluminum sulfate, and aluminum chloride.

[0013] Preferably, the ultrasonic frequency is 40–50 kHz and the ultrasonic time is 10–30 minutes.

[0014] Preferably, the first solution is stirred by a magnetic stirrer with a rotation speed of 500-800 rpm.

[0015] Preferably, the concentration of the second solution is in the range of 5 to 15 wt%, and the dropping rate of the second solution is 10 to 20 mL / min.

[0016] Preferably, the temperature range for heating and stirring the third solution is 80–150°C, the stirring time for heating and stirring the third solution is 10–15 hours, and the drying temperature is 65–90°C.

[0017] Preferably, the P2 type sodium-ion layered oxide electrode material is Na. 0.67 Ni a Fe b Mn c Mg d Al e O2 layered oxide electrode material, where a, b, c, d, e represent the atomic ratio of corresponding elements in the electrode material, 0≤a≤0.5, 0≤b≤0.5, 0.1≤c≤0.8, 0≤d≤0.3, 0≤e≤0.3.

[0018] Preferably, the calcination temperature of the precursor is 400–600°C, the calcination time is 4–10 hours, and the heating rate during calcination in an oxygen-free environment is 5–20°C / min.

[0019] Preferably, the inert gas in the high-temperature inert gas environment is argon or nitrogen, the heating rate of the high-temperature inert gas environment is 3-8℃ / min, the calcination temperature is 850-1050℃, and the calcination time is 10-15 hours.

[0020] Secondly, this application provides a P2-type sodium-electric layered oxide electrode material, which is prepared using the preparation method of the P2-type sodium-electric layered oxide electrode material provided in any embodiment of this application.

[0021] The present application has the following beneficial effects: The preparation method of the present application introduces oxygen vacancies by calcining P2 type layered oxide materials in an oxygen-free environment, thereby reducing the valence state of transition metal ions, so that more sodium ions can be inserted after the first discharge, thereby improving the specific capacity of subsequent charge and discharge; The electrode material of the present application has both capacity and cycle life. Attached Figure Description

[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0023] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 is a schematic flowchart of a method for preparing a P2 type sodium-ion layered oxide electrode material according to an embodiment of this application;

[0025] Figure 2 shows the Na prepared in Example 1 of this application. 0.67 Ni 0.31 Mn 0.65 Mg 0.04 SEM image of the O2 electrode material precursor. Detailed Implementation

[0026] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0027] In the description of this application, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] Please refer to Figure 1. A preferred embodiment of this application shows a method for preparing a P2-type sodium-ion layered oxide electrode material, comprising the following steps:

[0029] S1: Sodium, nickel, iron, manganese, magnesium, and aluminum sources are mixed, deionized water is added, and the mixture is dissolved by ultrasound. The mixture is then stirred to obtain a first solution. In this step, the sodium source includes, but is not limited to, sodium-containing compounds such as sodium carbonate and sodium acetate; the nickel source includes, but is not limited to, nickel-containing compounds such as nickel nitrate, nickel sulfate, nickel chloride, and nickel acetate; the iron source includes, but is not limited to, ferric nitrate, ferric sulfate, ferric chloride, and ferric acetate; the manganese source includes, but is not limited to, manganese-containing compounds such as manganese acetate, manganese nitrate, manganese sulfate, potassium permanganate, and manganese chloride; the magnesium source includes, but is not limited to, magnesium-containing compounds such as magnesium acetate, magnesium nitrate, magnesium chloride, and magnesium sulfate; and the aluminum source includes, but is not limited to, aluminum nitrate, aluminum sulfate, and aluminum chloride. The ultrasound frequency is 40–50 kHz, and the ultrasound time is 10–30 minutes. The first solution is stirred using a magnetic stirrer at a speed of 500–800 rpm.

[0030] S2: Dissolve oxalic acid in deionized water to obtain a second solution; in this step, the concentration of the second solution is in the range of 5–15 wt%.

[0031] S3: Add the second solution dropwise to the first solution and stir to obtain the third solution. Heat and stir the third solution. The dropping rate of the second solution is 10-20 mL / min. Specifically, after obtaining the third solution, transfer the third solution to a stainless steel autoclave lined with polytetrafluoroethylene, heat it to 80-150°C, and stir for 10-15 hours.

[0032] S4: After the third solution has cooled naturally, remove it, filter it, and dry it to obtain the precursor; the drying temperature in this step is 65-90℃.

[0033] S5: The precursor is calcined in an oxygen-free environment. After the precursor cools naturally, it is taken out and ground to obtain raw material powder. Specifically, the precursor is placed in a muffle furnace and calcined in an oxygen-free environment at a heating rate of 5-20℃ / min at a calcination temperature of 400-600℃ for 4-10 hours. After the precursor cools naturally, it is taken out and ground.

[0034] S6: The raw material powder is calcined in a high-temperature inert gas environment to obtain P2 type sodium-ion layered oxide electrode material. Specifically, in this step, the raw material powder is placed in a tube furnace, and argon or nitrogen gas is introduced. The inert gas in the high-temperature inert gas environment is argon or nitrogen. The material is calcined at a temperature of 850–1050°C for 10–15 hours with a heating rate of 3–8°C / min to obtain Na… 0.67 Ni a Fe b Mn c Mg d Al e O2 layered oxide electrode material, where a, b, c, d, e represent the atomic ratio of corresponding elements in the electrode material, 0≤a≤0.5, 0≤b≤0.5, 0.1≤c≤0.8, 0≤d≤0.3, 0≤e≤0.3.

[0035] Example 1

[0036] (1) Mix 8.21g manganese acetate tetrahydrate, 4.80g nickel nitrate hexahydrate, 0.54g magnesium acetate tetrahydrate and 3.02g sodium acetate trihydrate and dissolve them in 60mL of deionized water by ultrasonic stirring at a frequency of 40kHz for 10 minutes. Then transfer the mixture to a magnetic stirrer and set the speed of the magnetic stirrer to 500rpm for stirring.

[0037] (2) Dissolve 9g of oxalic acid in 50mL of deionized water, then transfer it to a 100mL volumetric flask and make up to volume.

[0038] Prepare a 1 mol / L oxalic acid solution.

[0039] (3) Add 65 mL of 1 mol / L oxalic acid solution slowly at a rate of 10 mL / min to the solution in step (1) while it is being stirred, and then transfer it to a stainless steel autoclave lined with polytetrafluoroethylene and stir at 120°C for 15 hours.

[0040] (4) After cooling, remove the reactor, filter, wash to obtain the precipitate, place it in a drying oven at 80°C to dry, and obtain the corresponding precursor.

[0041] (5) Place the precursor into a muffle furnace and calcine it at 600°C for 8 hours under air at a heating rate of 5°C / min. After natural cooling, take it out and grind it.

[0042] (6) Place the ground powder into a tube furnace, introduce argon gas, and heat at a rate of 5℃ / min at 1000℃.

[0043] Calcination for 12 hours yields Na 0.67 Ni 0.31 Mn 0.65 Mg0.04 O2 layered oxide electrode material, as shown in Figure 2. Figure 2 shows the Na prepared in Example 1. 0.67 Ni 0.31 Mn 0.65 Mg 0.04 SEM image of the O2 electrode material precursor.

[0044] Example 2

[0045] (1) Mix 6.13g manganese acetate tetrahydrate, 4.36g ferric acetate, 0.94g magnesium acetate tetrahydrate, and 3.02g sodium acetate trihydrate, and dissolve them in 60mL of deionized water by ultrasonic stirring at a frequency of 45kHz for 15 minutes. Then transfer the mixture to a magnetic stirrer and set the speed of the magnetic stirrer to 500rpm for stirring.

[0046] (2) Dissolve 9g of oxalic acid in 50mL of deionized water, then transfer it to a 100mL volumetric flask and make up to volume.

[0047] Prepare a 1 mol / L oxalic acid solution.

[0048] (3) Slowly add 70 mL of 1 mol / L oxalic acid solution to the solution in step (1) while it is being stirred, and then transfer it to a stainless steel autoclave lined with polytetrafluoroethylene and stir at 110°C for 12 hours.

[0049] (4) After cooling, remove the reactor, filter, wash to obtain the precipitate, place it in a drying oven at 80°C to dry, and obtain the corresponding precursor.

[0050] (5) Place the precursor into a muffle furnace and calcine it at 550°C for 7 hours under air at a heating rate of 5°C / min. After natural cooling, take it out and grind it.

[0051] (6) Place the ground powder into a tube furnace, introduce nitrogen gas, and heat at a rate of 5℃ / min at 975℃.

[0052] Calcination for 15 hours yields Na. 0.67 Fe 0.43 Mn 0.51 Al 0.06 O2 layered oxide electrode material.

[0053] Example 3

[0054] (1) Mix 7.61g manganese acetate tetrahydrate, 2.20g ferric acetate, 3.50g nickel nitrate hexahydrate, and 3.02g sodium acetate trihydrate, and dissolve them in 60mL of deionized water by ultrasonic stirring at a frequency of 50kHz for 20 minutes. Then transfer the mixture to a magnetic stirrer and set the speed of the magnetic stirrer to 500rpm for stirring.

[0055] (2) Dissolve 9g of oxalic acid in 50mL of deionized water, then transfer it to a 100mL volumetric flask and make up to volume.

[0056] Prepare a 1 mol / L oxalic acid solution.

[0057] (3) Slowly add 85 mL of 1 mol / L oxalic acid solution to the solution in step (1) while it is being stirred, and then transfer it to a stainless steel autoclave lined with polytetrafluoroethylene and stir at 120°C for 13 hours.

[0058] (4) After cooling, remove the reactor, filter, wash to obtain the precipitate, place it in a drying oven at 80°C to dry, and obtain the corresponding precursor.

[0059] (5) Place the precursor into a muffle furnace and calcine it at 600°C for 7 hours under air at a heating rate of 5°C / min. After natural cooling, take it out and grind it.

[0060] The ground powder was placed in a tube furnace, nitrogen gas was introduced, and it was calcined at 1050°C for 15 hours at a temperature rate of 5°C / min to obtain Na. 0.67 Ni 0.17 Fe 0.22 Mn 0.61 O2 layered oxide electrode material.

[0061] Example 4

[0062] Replace each data in Example 1 with the following data, while keeping others unchanged: the ultrasonic frequency in step (1) is 40 kHz, the ultrasonic time is 30 minutes, and the magnetic stirring speed is 500 rpm; the heating temperature in step (2) is 80 ℃, and the heating time is 15 hours; the oxalic acid solution dropping rate in step (3) is 10 mL / min; the drying temperature in step (4) is 65 ℃; the heating rate in step (5) is 5 ℃ / min, the calcination temperature is 400 ℃, and the sintering time is 10 hours; the inert gas in step (6) is nitrogen, the heating rate is 3 ℃ per minute, the calcination temperature is 850 ℃, and the calcination time is 15 hours, to obtain the P2 type sodium-ion layered oxide electrode material.

[0063] Example 5

[0064] Replace the data in Example 1 with the following data, while keeping the others unchanged: replace the ultrasonic frequency in step (1) with 50 kHz, the ultrasonic time with 10 minutes, and the magnetic stirring speed with 800 rpm; replace the heating temperature in step (2) with 150 ℃ and the heating time with 10 hours; replace the oxalic acid solution dropping rate in step (3) with 20 mL / min; replace the drying temperature in step (4) with 90 ℃; replace the heating rate in step (5) with 20 ℃ / min, the calcination temperature with 600 ℃, and the sintering time with 4 hours; replace the inert gas in step (6) with argon, the heating rate with 8 ℃ per minute, the calcination temperature with 1050 ℃, and the calcination time with 10 hours to obtain the P2 type sodium-ion layered oxide electrode material.

[0065] The capacity of the P2-type sodium-ion layered oxide electrode materials obtained in Examples 1, 2, and 3 was tested, and the specific values ​​are shown in the table below. Table 1 shows the specific capacity of the cathode materials in Examples 1, 2, and 3.

[0066] Table 1: Specific capacity of the cathode materials in Examples 1, 2, and 3

[0067]

[0068] As shown in Table 1, the data obtained from the tests in this application embodiment introduces oxygen vacancies into the material through calcination in an oxygen-free environment, which increases the number of sodium ions embedded between the material layers after the first discharge, thereby improving its specific capacity to 121.6 mAh / g. The specific capacity of the cathode material in Example 1 even reaches 131.4 mAh / g, which is higher than the 110 mAh / g of the prior art. The preparation method of this application has obtained a sodium-ion battery cathode material with both capacity and cycle life, which can be used in energy storage products, A0-class electric vehicles, two-wheeled electric vehicles, and low-cost energy storage devices.

[0069] The above are merely preferred embodiments of this application; however, the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and its improved concept, should be covered within the scope of protection of this application.

Claims

1. A method for preparing a P2-type sodium-ion layered oxide electrode material, characterized in that, Includes the following steps: Sodium, nickel, iron, manganese, magnesium, and aluminum sources are mixed, and deionized water is added to dissolve them together by ultrasound. The mixture is then stirred to obtain the first solution. Oxalic acid is dissolved in deionized water to obtain the second solution. The second solution is added dropwise to the first solution while stirring to obtain a third solution, which is then heated and stirred. After the third solution cools naturally, it is removed, filtered, and dried to obtain a precursor. The precursor is calcined in an oxygen-free environment. After the precursor cools naturally, it is removed and ground to obtain raw material powder. The calcination temperature of the precursor is 400–600℃, the calcination time is 4–10 hours, and the heating rate in the oxygen-free environment is 5–20℃ / min. The raw material powder is placed in a high-temperature inert gas environment for calcination to obtain P2 type sodium-ion layered oxide electrode material. The inert gas in the high-temperature inert gas environment is argon or nitrogen. The heating rate in the high-temperature inert gas environment is 3–8℃ / min, the calcination temperature is 850–1050℃, and the calcination time is 10–15 hours.

2. The method for preparing a P2-type sodium-ion layered oxide electrode material according to claim 1, characterized in that, The sodium source includes one or more of sodium carbonate and sodium acetate; the nickel source includes one or more of nickel nitrate, nickel sulfate, nickel chloride, and nickel acetate; the iron source includes one or more of ferric nitrate, ferric sulfate, ferric chloride, and ferric acetate; the manganese source includes one or more of manganese acetate, manganese nitrate, manganese sulfate, potassium permanganate, and manganese chloride; the magnesium source includes one or more of magnesium acetate, magnesium nitrate, magnesium chloride, and magnesium sulfate; and the aluminum source includes one or more of aluminum nitrate, aluminum sulfate, and aluminum chloride.

3. The method for preparing a P2-type sodium-ion layered oxide electrode material according to claim 1 or 2, characterized in that, The ultrasonic frequency is 40–50 kHz, and the ultrasonic time is 10–30 minutes.

4. The method for preparing a P2-type sodium-ion layered oxide electrode material according to claim 3, characterized in that, The first solution is stirred by a magnetic stirrer at a speed of 500-800 rpm.

5. The method for preparing a P2-type sodium-ion layered oxide electrode material according to claim 4, characterized in that, The concentration range of the second solution is 5–15 wt%, and the dropping rate of the second solution is 10–20 mL / min.

6. The method for preparing a P2-type sodium-ion layered oxide electrode material according to claim 1, characterized in that, The third solution is heated and stirred at a temperature range of 80–150°C for 10–15 hours, and the drying temperature is 65–90°C.

7. The method for preparing a P2-type sodium-ion layered oxide electrode material according to claim 6, characterized in that, The P2 type sodium-ion layered oxide electrode material is Na. 0.67 Ni a Fe b Mn c Mg d Al e O2 layered oxide electrode material, where a, b, c, d, e represent the atomic ratio of corresponding elements in the electrode material, 0≤a≤0.5, 0≤b≤0.5, 0.1≤c≤0.8, 0≤d≤0.3, 0≤e≤0.

3.

8. A P2-type sodium-ion layered oxide electrode material, characterized in that, It was prepared using the preparation method of the P2 type sodium-electric layered oxide electrode material according to any one of claims 1-7.

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