Preparation method of sodium ion battery positive electrode material suitable for different application scenes of normal temperature and low temperature

Abstract

The invention discloses a preparation method of a sodium-ion battery positive electrode material suitable for different application scenes of normal temperature and low temperature, and the preparation method comprises the following steps: firstly, dissolving nickel salt, magnesium salt and manganese salt in a solvent to form a mixed salt solution; dissolving sodium carbonate in a solvent to prepare a precipitant solution; adding the mixed salt solution into the precipitant solution; then, transferring the mixed solution into a reaction kettle for stirring reaction, and after the reaction is completed, filtering and washing a product to obtain a carbonate precursor; drying the carbonate precursor, and calcining in a kiln to obtain an oxide precursor; and finally, adding a sodium source into the oxide precursor, uniformly mixing, and calcining in a kiln to obtain the catalyst. According to the method disclosed by the invention, the preparation of the sodium-ion battery positive electrode material used in different application scenes of normal temperature and low temperature can be realized by selecting the specific transition metal and the optimal element ratio, good electrochemical performance is maintained, the dual-carbon economy is met, and the method is particularly suitable for being applied to the field of large-scale energy storage.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of application of alkali metal, i.e. sodium, compounds in new type secondary batteries, in particular to a preparation method of a sodium ion battery positive electrode material suitable for different application scenarios at normal temperature and low temperature. BACKGROUND

[0002] Energy storage systems are one of the important supporting technologies for achieving the carbon peak and carbon neutralization targets, and are an important means to smooth new energy fluctuations and reduce the impact of large-scale new energy access on the power grid. At present, global energy resource competition is becoming increasingly fierce, and China is also facing major changes in energy structure adjustment. To implement the energy strategy of "four revolutions and one cooperation" in the new era and achieve the 2035 vision, China needs to be driven by clean, low-carbon, safe and efficient energy, and build a new energy structure system with Chinese characteristics that is compatible with energy resources. Under the background of the "double carbon" target and the accelerated transformation of energy structure, new battery technology has become a key track for industrial upgrading. Among many electrochemical energy storage technologies, lithium ion batteries have dominated portable electronic devices and new energy vehicles, forming a relatively complete industrial chain. However, at the same time, the shortcomings of lithium ion batteries have also attracted attention. One of the shortcomings is the scarcity of lithium resources. Experts say that globally, lithium resources are extremely unevenly distributed, with about 70% in South America, and China's lithium resources accounting for only 16.5% of the world's total. Similar to lithium ion batteries, sodium ion batteries are a type of secondary battery that relies on the migration of sodium ions between the positive and negative electrodes to complete charging and discharging. Globally, the reserves of sodium far exceed those of lithium and are widely distributed, and the cost of sodium ion batteries is 30%-40% lower than that of lithium batteries. In January 2023, the Ministry of Industry and Information Technology and other six departments jointly issued the "Guiding Opinions on Promoting the Development of Energy Electronics Industry", which clearly stated that efforts should be made to strengthen the industrialization of new energy storage batteries, research breakthroughs in key technologies such as ultra-long life high safety battery systems, large-scale high-capacity high-efficiency energy storage, and accelerate the development of new batteries such as sodium ion batteries.

[0003] Among the many sodium-ion battery cathode materials, layered oxides have become a research hotspot due to their good electronic conductivity and ion diffusion rate and other kinetic performance. Although the design of the current sodium-ion battery cathode material will refer to the lithium-ion battery cathode material, the structures of the two materials are completely different. The larger ionic radius of sodium ions often cannot be fully arranged in the sodium layer. The content of nickel in the layered oxide of the lithium-ion battery can be designed to be very high, but in the layered oxide of the sodium-ion battery, due to the larger ionic radius of sodium ions, the content of nickel cannot be higher than 0.35. In order to better maintain the stability of the layered structure, when designing the layered oxide of the sodium-ion battery, the content of manganese is limited to be higher than 0.5. In addition, compared with the lithium-ion battery, the sodium-ion battery has obvious low-temperature performance advantage in addition to the cost advantage. The main reason is that the solvation energy (the strength of the combination of ions and solvent molecules) of sodium ions in aqueous solution or organic electrolyte is lower than that of lithium ions. At low temperature, ions need to "break free" from the solvation shell to be embedded into the electrode material, and the energy required for sodium ions to desolvate is smaller, so the migration resistance is smaller at low temperature. At present, the research on the cathode material of the sodium-ion battery mainly focuses on improving the energy density, rate performance, cycle stability and other electrochemical performance of the sodium-ion battery, and requires that the cathode material of the sodium-ion battery must have the ability of highly reversible sodium ion extraction / insertion. However, most of the current electrochemical performance tests are carried out at room temperature, and temperature has a great influence on the ion extraction process in the secondary battery, mainly because the influence of low temperature on the redox reaction of different metals is different. The common active sites of layered oxide materials such as lithium, cobalt, aluminum, copper and iron have a relatively high activation energy barrier, which leads to poor electrochemical performance at low temperature when the redox reaction occurs. In order to better meet the demand of large-scale energy storage, it is required that the sodium-ion battery can exhibit excellent electrochemical performance at different temperature scenarios. At present, the new energy market has less research on the low-temperature performance of the sodium-ion battery, so in order to maximize the advantages of the application of the sodium-ion battery, when designing the cathode material of the sodium-ion battery, a transition metal with strong low-temperature tolerance should be selected as the active site to ensure that the sodium-ion battery can maintain good electrochemical performance at room temperature and low temperature. SUMMARY

[0004] In view of the above defects of the prior art, the present application selects nickel, magnesium and manganese as the active sites of the cathode layered oxide of the sodium-ion battery, wherein the nickel element corresponds to Ni 2+ / 3+ The entropy change of the redox reaction has obvious advantages over other metals such as copper, aluminum, iron and cobalt, and in addition, Ni 2+ / 3+The redox reaction provides charge compensation at room temperature, which has obvious advantages over other variable valence transition metals. Magnesium does not undergo redox reaction in the positive electrode layered oxide material of the application, so it can well avoid the influence of low temperature. Manganese element mainly plays a supporting role in the structure of layered oxide, in addition, the specific element metering ratio designed in the application can effectively improve the valence state of manganese in the synthesized positive electrode layered oxide, so that the valence state of manganese is closer to the positive four valence. The closer the valence state of manganese in the positive electrode layered oxide is to the positive four valence, the lower the content of trivalent manganese ions in the material, that is, the Mn 3+ / 4+ The proportion of redox reaction involved in charge compensation effectively inhibits the influence of low temperature on its electrochemical performance. The technical problem to be solved by the application is the poor low-temperature performance and the inhibition effect of sodium / vacancy ordered arrangement on sodium ion diffusion rate in the existing mainstream sodium ion battery positive electrode layered oxide material.

[0005] To achieve the above-mentioned purpose, the application provides a preparation method of a sodium ion battery positive electrode material suitable for different application scenarios at room temperature and low temperature, comprising the following steps:

[0006] Step 1, dissolve nickel salt, magnesium salt and manganese salt in a first solvent to form a mixed salt solution; at the same time, dissolve the precipitating agent sodium carbonate in a second solvent to prepare a precipitating agent solution; after the two solutions are completely dissolved, the mixed salt solution is added to the precipitating agent solution at a constant speed to obtain a mixed solution;

[0007] Step 2, transfer the mixed solution obtained in step 1 to a reaction kettle for stirring reaction to obtain a reaction product;

[0008] Step 3, filter and wash the reaction product obtained in step 2 to obtain a carbonate precursor;

[0009] Step 4, dry the carbonate precursor obtained in step 3 and calcine it in a kiln to obtain an oxide precursor;

[0010] Step 5, add a sodium source to the oxide precursor obtained in step 4, mix uniformly and calcine in a kiln to obtain a layered sodium ion battery positive electrode material.

[0011] Further, in step 1, the molar ratio of Ni, Mg and Mn elements in the nickel salt, magnesium salt and manganese salt is 3:x:(7-x), 0

[0012] Further, in step 1, the first solvent and / or the second solvent is independently selected from one or a mixture of two of water, ethylene glycol or polyethylene glycol.

[0013] Further, in step 1, the nickel salt, magnesium salt and manganese salt are independently selected from one or a mixture of two of sulfate, nitrate, acetate or chloride.

[0014] Further, the amount of sodium carbonate in step 1 corresponds to 1-1.8 times the total amount of nickel, magnesium and manganese metal ions.

[0015] Further, the addition rate of the mixed salt solution in step 1 is 10-50 ml / min.

[0016] Further, the reaction temperature in step 2 is 50-90℃, the reaction time is 5-10h, and the stirring speed is 300-700rpm.

[0017] Further, the calcination temperature in step 4 is 400-700℃, and the calcination time is 3-7h.

[0018] Further, the sodium source in step 5 is one of sodium acetate, sodium oxalate or sodium nitrate, or a mixture of two of them.

[0019] The ratio of the molar amount of sodium in the sodium source to the total molar amount of nickel, magnesium and manganese metal ions is (0.5-0.85):1.

[0020] Further, the calcination process in step 5 adopts a stepwise temperature rising mode: first calcination at 300-700℃ for 3-7h, then heating to 800-1000℃ for 10-15h, and the heating rate of each stage is 1-5℃ / min.

[0021] The beneficial effects of the present application are:

[0022] The present application is mainly aimed at the problem that the performance difference of sodium ion battery cathode material at room temperature and low temperature is large, which is difficult to meet the large-scale energy storage in different application scenarios. The three metal elements selected in the present application play different roles in the layered oxide cathode material: the charge compensation provided by the redox reaction of nickel is the highest among the metal elements, Ni 2+ / 3+ The temperature influence on the potential dominated by the entropy change of redox reaction is also the smallest; magnesium metal can play a role in stabilizing the structure and will not undergo redox reaction, so the influence of low temperature on it is very small; manganese element can better approach the positive tetravalence under the metal element stoichiometric ratio designed in the present application, which can ensure that manganese is more used to support the layered structure, and Mn 3+ / 4+The ratio of redox reactions is effectively reduced, and ultimately realizes that manganese provides a small amount of charge compensation while its electrochemical performance is less affected by temperature. The combination of the advantages of the three elements can effectively improve the electrochemical performance of the layered oxide at room temperature and low temperature, and can effectively inhibit the sodium / vacancy ordered arrangement commonly seen in sodium ion battery layered oxide materials. The present application effectively improves the room temperature and low temperature performance of the sodium ion battery layered oxide by precise design of the selection and ratio of transition metal layer metal elements, ensuring that the sodium ion battery is better applicable to different temperature application scenarios, and making it better applicable to large-scale energy storage field. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, together with the embodiments of the application, to explain the application, and do not constitute a limitation on the application. In the drawings:

[0024] Figure 1 is the refined XRD graph of the sodium ion battery layered material prepared in Example 1 of the present application;

[0025] Figure 2 is the scanning electron microscope graph of the sodium ion battery layered material prepared in Example 2;

[0026] Figure 3 is the first two circle charge-discharge curve graph of the sodium ion battery layered material prepared in Example 2;

[0027] Figure 4 is the rate performance graph of the sodium ion battery layered material prepared in Example 3 tested at-20 DEG C;

[0028] Figure 5 is the low temperature box used when testing the low temperature performance of the sodium ion battery layered material prepared in Example 4.

[0029] Figure 6 is the first circle charge-discharge curve comparison of the sodium ion battery layered material prepared in Example 4 under different conditions of room temperature and low temperature.

[0030] Figure 7 is the first circle charge-discharge curve comparison of the sodium ion battery layered material prepared in Comparative Example 1 under different conditions of room temperature and low temperature.

[0031] Figure 8 is the first circle cyclic voltammetry curve comparison of the sodium ion battery layered material obtained in Comparative Example 2 under different conditions of room temperature and low temperature.

[0032] Figure 9 is the first circle charge-discharge curve comparison of the lithium ion battery layered material obtained in Comparative Example 3 under different conditions of room temperature and low temperature. DETAILED DESCRIPTION

[0033] The technical content of the present application will be described in more detail below with reference to the accompanying drawings of the specification, so that it is more clear and convenient to understand. The present application can be embodied in many different forms of embodiments, and the protection scope of the present application is not limited to the embodiments mentioned herein.

[0034] Example 1:

[0035] A preparation method of a sodium ion battery cathode material suitable for different application scenarios at room temperature and low temperature, comprising the following steps:

[0036] Step 1, nickel sulfate, magnesium chloride and manganese acetate are added to water in a molar ratio of 3:1:6, and sodium carbonate corresponding to 1.2 times the total amount of nickel, magnesium and manganese metal ions is dissolved in ethanol, and after both are completely dissolved, the metal salt mixed solution is injected into the sodium carbonate solution at a speed of 10ml / min;

[0037] Step 2, the mixed solution obtained in step 1 is transferred to a reaction kettle, and reacted at 60°C for 8h, with a stirring speed of 300r / min;

[0038] Step 3, filter and wash the reaction product of step 2 to obtain a carbonate precursor, and dry it in a blast oven at 90°C for 10h;

[0039] Step 4, after drying the carbonate precursor in the kiln after step 3, it is calcined in the kiln at 500°C for 5h to prepare an oxide precursor;

[0040] Step 5, sodium nitrate is added to the oxide precursor obtained in step 4, and the molar ratio of sodium element in the added amount of sodium nitrate to metal ions is 0.75:1; After mixing uniformly, it is first heated to 500°C in the kiln, and kept at 500°C for 4h, and then heated to 950°C for calcination for 10h, with a whole heating rate of 5°C / min. A layered sodium ion battery cathode material is obtained.

[0041] Figure 1 is the XRD refinement figure of the sodium ion battery layered material prepared in Example 1, all the diffraction peaks can be one-to-one corresponding to the standard XRD card, indicating that the material synthesized by the process of this embodiment is a pure phase. In addition, it has no impurity small peak between 25°-30°, which represents that the sodium / vacancy ordered arrangement is effectively inhibited.

[0042] Example 2:

[0043] A preparation method of a sodium ion battery cathode material suitable for different application scenarios at room temperature and low temperature, comprising the following steps:

[0044] Step 1, nickel nitrate, magnesium nitrate and manganese sulfate are added to water in a molar ratio of 3:2:5, and sodium carbonate corresponding to 1.5 times the total amount of nickel, magnesium and manganese metal ions is dissolved in ethanol, and after both are completely dissolved, the metal salt mixed solution is injected into the sodium carbonate solution at a speed of 15 ml / min;

[0045] Step 2, the mixed solution obtained in step 1 is transferred to a reaction kettle, and reacted at 80°C for 6h with a stirring speed of 500rpm;

[0046] Step 3, the reaction product of step 2 is filtered and washed, and the obtained carbonate precursor is dried in a blast oven at 90°C for 10h;

[0047] Step 4, the carbonate precursor dried in step 3 is calcined in a kiln at 600°C for 4h to prepare an oxide precursor;

[0048] Step 5, sodium acetate is added to the oxide precursor obtained in step 4, and the molar ratio of Na element in the added amount of sodium acetate to metal ions is 0.6:1; after mixing uniformly, it is first heated to 600°C in a kiln, and then heated to 1100°C for calcination for 10h, and the overall heating rate is 2°C / min, to obtain a layered sodium-ion battery cathode material.

[0049] Figure 2 Figure 1 is a scanning electron microscope morphology diagram of the sodium-ion battery cathode layered material prepared in Example 2, and it can be seen from the figure that the particle size of the synthesized cathode material is relatively uniform, and the particle size distribution is about 2-3 microns.

[0050] Figure 3 Figure 2 is the first two circle charge-discharge curves of the sodium-ion battery cathode layered material prepared in Example 2, and the material prepared in this example can exhibit specific capacities of 98.9 and 98.6 mAh / g in the first two circles, showing excellent electrochemical reversible performance, and the charge-discharge curve is relatively smooth, indicating that the sodium vacancy is effectively inhibited.

[0051] Example 3:

[0052] A preparation method of a sodium-ion battery cathode material suitable for different application scenarios at room temperature and low temperature, comprising the following steps:

[0053] Step 1, nickel chloride, magnesium acetate and manganese nitrate are added to polyethylene glycol in a molar ratio of 3:1.5:5.5, and sodium carbonate corresponding to 1.5 times the total amount of nickel, magnesium and manganese metal ions is dissolved in water, and after both are completely dissolved, the metal salt mixed solution is injected into the sodium carbonate solution at a speed of 30 ml / min;

[0054] Step 2, the mixed solution obtained in step 1 is transferred to a reaction kettle, and reacted at 90°C for 8h, with a stirring speed of 600rpm;

[0055] Step 3, the reaction product of step 2 is filtered and washed, and the obtained carbonate precursor is dried in a blast oven at 90°C for 10h;

[0056] Step 4, the carbonate precursor dried in step 3 is calcined in a kiln at 700°C for 3h after drying in the kiln, thereby preparing an oxide precursor;

[0057] Step 5, sodium acetate is added to the oxide precursor obtained in step 4, wherein the molar ratio of sodium element in the added amount of sodium acetate to metal ions is 0.65:1; after uniform mixing, it is first heated to 550°C in a kiln, and then heated to 850°C for calcination for 12h after staying at 550°C for 5h, with a whole heating rate of 3°C / min, thereby obtaining a layered sodium-ion battery cathode material.

[0058] Figure 4 is the rate performance graph of the sodium-ion battery cathode layered material prepared in Example 3 measured at low temperature. The material prepared in this example can exhibit specific capacities of 73.2, 66.3, 60.5, 55.1, 49.6 and 32.3mAh / g at rates of 0.2, 0.5, 1, 2, 5 and 10C at -20°C, and still exhibits excellent rate performance in a low-temperature environment.

[0059] Example 4:

[0060] A preparation method of a sodium-ion battery cathode material suitable for different application scenarios at room temperature and low temperature, comprising the following steps:

[0061] Step 1, nickel sulfate, magnesium sulfate and manganese sulfate are added to ethanol in a molar ratio of 3:0.2:6.8, and sodium carbonate is dissolved in water in an amount of 1.5 times the total amount of nickel, magnesium and manganese metal ions corresponding to carbonate, and after both are completely dissolved, the metal salt mixed solution is injected into the sodium carbonate solution at a speed of 20ml / min;

[0062] Step 2, the mixed solution obtained in step 1 is transferred to a reaction kettle, and reacted at 60°C for 10h, with a stirring speed of 400rpm;

[0063] Step 3, the reaction product of step 2 is filtered and washed, and the obtained carbonate precursor is dried in a blast oven at 90°C for 10h;

[0064] Step 4, the carbonates precursor after drying in the oven is calcined in the oven at 500℃ for 5h, thereby obtaining an oxide precursor;

[0065] Step 5, sodium oxalate is added to the oxide precursor obtained in step 4, wherein the molar ratio of Na element in the added amount of sodium oxalate to metal ions is 0.7:1; after mixing uniformly, it is first heated to 500℃ in the oven, and then kept at 500℃ for 7h, and then continuously heated to 900℃ for calcination for 15h, and the overall heating rate is 5℃ / min, thereby obtaining a layered sodium-ion battery positive electrode material.

[0066] Figure 5 A low-temperature box used for testing the low-temperature electrochemical performance of the sodium-ion battery positive electrode layered material prepared in Example 4.

[0067] Figure 6 A comparison of the first cycle charge and discharge specific capacity of the sodium-ion battery positive electrode layered material prepared in Example 4 measured at room temperature and low temperature under different conditions. Under the condition of 0.2C rate, the specific capacity obtained by testing at different temperatures only differs by 8 milliampere hours / gram, which shows excellent room temperature and low temperature performance.

[0068] Comparative Example 1:

[0069] A preparation method of a sodium-ion battery positive electrode material, comprising the following steps:

[0070] Step 1, copper sulfate, aluminum sulfate and manganese sulfate are added to ethanol in a molar ratio of 3:1:6, and sodium carbonate corresponding to 1.5 times the total amount of copper, aluminum and manganese metal ions is dissolved in water, and after both are completely dissolved, the metal salt mixed solution is injected into the sodium carbonate solution at a speed of 20ml / min;

[0071] Step 2, the mixed solution obtained in step 1 is transferred to a reaction kettle, and reacted at 60℃ for 10h, with a stirring speed of 400 revolutions / minute;

[0072] Step 3, the reaction product of step 2 is filtered and washed to obtain a carbonate precursor, and the carbonate precursor is dried in a blast oven at 90℃ for 10h;

[0073] Step 4, the carbonates precursor after drying in the oven is calcined in the oven at 500℃ for 5h, thereby obtaining an oxide precursor;

[0074] Step 5, sodium oxalate is added to the oxide precursor obtained in step 4, and the molar ratio of sodium element in the added sodium oxalate to metal ions is 0.7:1; after uniform mixing, it is first heated to 500°C in a kiln, stays at 500°C for 7h, and then continues to be heated to 900°C for calcination for 15h, and the overall heating rate is 5°C / min. Layered sodium-ion battery cathode material can be obtained.

[0075] Figure 7 The first circle charge-discharge specific capacity measured under different conditions at room temperature and low temperature of the sodium-ion battery cathode layered material prepared in Comparative Example 1 is compared. The specific capacity obtained by testing at different temperatures under 0.2C rate is 16.5mAh / g, which is obviously larger than the capacity difference between room temperature and low temperature in the scheme of Example 4.

[0076] Comparative Example 2

[0077] A preparation method of a sodium-ion battery cathode material, comprising the following steps:

[0078] Step 1, nickel sulfate, cobalt sulfate and manganese sulfate are added to water in a molar ratio of 3:0.5:6.5, and sodium carbonate is dissolved in water in a molar ratio of 1.8 times the total amount of nickel, cobalt and manganese metal ions corresponding to the carbonate. After both are completely dissolved, the metal salt mixed solution is injected into the sodium carbonate solution at a speed of 40ml / min;

[0079] Step 2, the mixed solution obtained in step 1 is transferred to a reaction kettle, and reacted at 70°C for 10h with a stirring speed of 300r / min;

[0080] Step 3, the reaction product of step 2 is filtered and washed to obtain a carbonate precursor, and the carbonate precursor is dried in a blast oven at 90°C for 10h;

[0081] Step 4, the carbonate precursor dried in step 3 is dried in a kiln and then calcined at 600°C in the kiln for 3h to prepare an oxide precursor;

[0082] Step 5, sodium nitrate is added to the oxide precursor obtained in step 4, and the molar ratio of sodium element in the added sodium nitrate to metal ions is 0.75:1; after uniform mixing, it is first heated to 500°C in a kiln, stays at 500°C for 7h, and then continues to be heated to 900°C for calcination for 15h, and the overall heating rate is 5°C / min. Layered sodium-ion battery cathode material can be obtained.

[0083] Figure 8The first cycle cyclic voltammetry curves of the sodium ion battery positive electrode layered material prepared in Comparative Example 2 were measured under different conditions at room temperature and low temperature. As can be seen from the figure, the redox peak difference of the oxide positive electrode material prepared by using nickel, cobalt and manganese as active sites is obvious at different temperatures, indicating that the electrochemical performance at room temperature and low temperature of the comparative example also has a large difference.

[0084] Comparative Example 3

[0085] A preparation method of a lithium ion battery positive electrode material, comprising the following steps:

[0086] Step 1, nickel sulfate, magnesium sulfate and manganese sulfate are added to water in a molar ratio of 3:0.5:6.5, and sodium carbonate corresponding to 1.8 times the total amount of nickel, cobalt and manganese metal ions is dissolved in water, and after both are completely dissolved, the metal salt mixed solution is punched into the sodium carbonate solution at a speed of 50 ml / min;

[0087] Step 2, the mixed solution obtained in step 1 is transferred to a reaction kettle, and reacted at 70°C for 10h, with a stirring speed of 300r / min;

[0088] Step 3, the reaction product of step 2 is filtered and washed to obtain a carbonate precursor, and the carbonate precursor is dried in a blast oven at 90°C for 10h;

[0089] Step 4, the carbonate precursor dried in step 3 is dried in a kiln and calcined in the kiln at 500°C for 3h, thereby preparing an oxide precursor;

[0090] Step 5, lithium carbonate is added to the oxide precursor obtained in step 4, wherein the molar ratio of lithium element in the lithium carbonate addition amount to metal ions is 1.05:1; after mixing uniformly, it is first heated to 500°C in a kiln, and then stopped at 500°C for 5h, and then continues to heat to 850°C for calcination for 10h, and the overall heating rate is 5°C / min. A layered lithium ion battery positive electrode material is obtained.

[0091] Figure 9 The first cycle charge-discharge specific capacity of the lithium ion battery positive electrode layered material prepared in Comparative Example 3 was measured under different conditions at room temperature and low temperature. The specific capacity obtained by testing at different temperatures under the condition of 0.2C rate differs by 69 milliampere hours / gram. The capacity difference of the sodium ion battery positive electrode material designed in the embodiment of the application at room temperature and low temperature is undoubtedly huge. This also shows that the design idea of the application can only be applied to the application scene of sodium ion battery at low temperature.

[0092] The application provides a preparation method of a sodium ion battery positive electrode material suitable for different application scenes at normal temperature and low temperature, characterized by selecting specific metal ions as active sites of the sodium ion battery positive electrode material, and simply controlling the stoichiometric ratio of the metal ions, so that the sodium ion battery positive electrode material with excellent normal temperature and low temperature electrochemical performance is prepared, and the inhibition effect of sodium / vacancy ordered arrangement on sodium ion diffusion rate is effectively solved.

[0093] The preferred embodiments of the application are described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and changes without creative labor based on the concept of the application. Therefore, any technical solutions obtained by logical analysis, reasoning or limited experiments based on the prior art according to the concept of the application shall be within the protection scope defined by the claims.

Claims

1. A method for preparing a sodium-ion battery cathode material suitable for different application scenarios at room temperature and low temperature, characterized in that, The method comprises the following steps: Step 1: dissolving nickel salt, magnesium salt and manganese salt in a first solvent to form a mixed salt solution; meanwhile, dissolving a precipitant sodium carbonate in a second solvent to form a precipitant solution; after the two solutions are completely dissolved, adding the mixed salt solution into the precipitant solution at a constant speed to obtain a mixed solution; Step 2: transferring the mixed solution obtained in step 1 into a reaction kettle for stirring reaction to obtain a reaction product; Step 3: filtering and washing the reaction product obtained in step 2 to obtain a carbonate precursor; Step 4: drying the carbonate precursor obtained in step 3 and calcining in a kiln to obtain an oxide precursor; Step 5: adding a sodium source into the oxide precursor obtained in step 4, uniformly mixing and calcining in a kiln to obtain a layered sodium-ion battery positive electrode material.

2. The production method according to claim 1, characterized by, In step 1, the molar ratio of Ni, Mg and Mn elements in the nickel salt, the magnesium salt and the manganese salt is 3:x:(7-x), and 0 3. The preparation method according to claim 1, characterized in that, In step 1, the first solvent and / or the second solvent is independently selected from one or a mixture of two of water, ethylene glycol or polyethylene glycol.

4. The method of claim 1, wherein, In step 1, the nickel salt, the magnesium salt and the manganese salt are independently selected from one or a mixture of two of a sulfate, a nitrate, an acetate or a chloride.

5. The preparation method according to claim 1, characterized in that, In step 1, the amount of sodium carbonate corresponds to 1-1.8 times the total amount of moles of nickel, magnesium and manganese metal ions.

6. The method of claim 1, wherein, In step 1, the adding rate of the mixed salt solution is 10-50 ml / min.

7. The preparation method according to claim 1, characterized in that, In step 2, the reaction temperature is 50-90℃, the reaction time is 5-10h, and the stirring speed is 300-700rpm.

8. The method of claim 1, wherein, In step 4, the calcination temperature is 400-700℃, and the calcination time is 3-7h.

9. The method of claim 1, wherein, In step 5, the sodium source is one or a mixture of two of sodium acetate, sodium oxalate or sodium nitrate; The ratio of the molar amount of sodium in the sodium source to the total molar amount of nickel, magnesium and manganese metal ions is (0.5-0.85):1; In step 5, the calcination process adopts a stepwise temperature rising mode: first calcining at 300-700℃ for 3-7h, then raising the temperature to 800-1000℃ for calcination for 10-15h, and the temperature rising rate of each stage is 1-5℃ / min.

10. A sodium-ion battery cathode material prepared by the method of any one of claims 1-9, wherein the sodium-ion battery cathode material has a capacity of at least 150 mAh / g. The sodium-ion battery positive electrode material has excellent electrochemical performance at room temperature and low temperature environments.

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