Titanium-doped NFPP positive electrode material, precursor thereof, preparation method of titanium-doped NFPP positive electrode material and sodium ion battery

Abstract

The invention provides a titanium-doped NFPP positive electrode material, a precursor of the titanium-doped NFPP positive electrode material, a preparation method of the titanium-doped NFPP positive electrode material and a sodium ion battery, and the preparation method comprises the following steps: (1) mixing sodium phosphate, sodium pyrophosphate and a first solvent to form a solution A; and (2) introducing the solution A, hydrogen peroxide and a sodium hydroxide solution into a base solution containing ferrous sulfate and titanium ions, and carrying out a co-precipitation reaction in a protective atmosphere to prepare the titanium-doped NFPP positive electrode material precursor. The titanium-doped NFPP positive electrode material precursor with uniformly distributed positive electrode material elements can be obtained, and the rate capability of the positive electrode material is improved.

Description

Technical Field

[0001] This invention relates to the field of cathode material technology, and in particular to a titanium-doped NFPP cathode material, its precursor, its preparation method, and a sodium-ion battery. Background Technology

[0002] Energy storage systems are a crucial component of renewable energy development and utilization, with electrochemical energy storage systems based on secondary batteries possessing a wide range of applications. Although lithium-ion batteries have been widely used in new energy vehicles, electronic products, and other fields, the uneven distribution of lithium resources has led to an increasingly prominent supply-demand imbalance in the lithium salt market.

[0003] Sodium, as a group element with lithium, not only has similar chemical properties to lithium, but is also widely available and inexpensive, making sodium-ion batteries a promising secondary battery technology for large-scale application.

[0004] Sodium-ion battery cathode materials mainly encompass oxides, polyanionic compounds, Prussian blue compounds, and organic cathode materials, among which oxides and polyanionic cathode materials have attracted significant attention. Oxide cathode materials have a theoretically high specific capacity, making them suitable for developing high-energy-density rechargeable batteries; while polyanionic compound cathode materials, with their excellent cycle performance, high safety, and low raw material costs, have become the preferred choice for large-scale commercialization.

[0005] Based on the differences in anion type, polyanionic cathode materials can be classified into sulfate, phosphate, pyrophosphate, silicate, and mixed phosphate / pyrophosphate salts. Among these types, sodium iron pyrophosphate is the most extensively studied iron-based polyanionic cathode material, possessing high theoretical capacity, stable operating voltage, and excellent cycle performance. It is a cathode material with both good application prospects and cost advantages.

[0006] However, sodium iron pyrophosphate cathode materials synthesized using traditional methods suffer from problems such as poor electronic conductivity, low compaction density, and high cost, making it difficult to meet the needs of practical applications.

[0007] Therefore, it is of great significance to prepare sodium-ion battery cathode materials with better rate performance and lower cost by controlling the composition and structure of materials and optimizing the preparation process. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a titanium-doped NFPP cathode material, its precursor, a preparation method thereof, and a sodium-ion battery. Through process optimization, a low-cost cathode material is obtained, and the rate performance of the cathode material is improved by doping with a small amount of titanium. Ultimately, the sodium-ion battery cathode material prepared by the method provided by this invention exhibits superior rate performance.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for preparing a titanium-doped NFPP cathode material precursor, the method comprising the following steps:

[0011] (1) Mix sodium phosphate, sodium pyrophosphate and the first solvent to form solution A.

[0012] (2) Solution A, hydrogen peroxide and sodium hydroxide solution are passed into a bottom liquid containing ferrous sulfate and titanium ions, and a co-precipitation reaction is carried out in a protective atmosphere to prepare a titanium-doped NFPP cathode material precursor.

[0013] The titanium-doped NFPP cathode material precursor prepared by the present invention is obtained by co-precipitation. In the co-precipitation process, a certain proportion of iron source and phosphorus source are used, and hydrogen peroxide is added as an oxidant. In addition, sodium hydroxide solution is added to control the pH of the reaction, so as to obtain a uniformly titanium-doped NFPP cathode material precursor. After calcination, the precursor has fewer impurities, which can improve the rate performance of the cathode material.

[0014] Preferably, the molar concentration of sodium phosphate in solution A in step (1) is 0.1~2 mol / L, for example, it can be 0.1 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L or 2 mol / L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0015] Preferably, the molar concentration of sodium pyrophosphate in solution A is 0.1~2 mol / L, for example, it can be 0.1 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L or 2 mol / L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0016] Preferably, the molar concentration of the hydrogen peroxide is 5~15 mol / L, for example, it can be 5 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, 10 mol / L, 11 mol / L, 12 mol / L, 13 mol / L, 14 mol / L or 15 mol / L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0017] Preferably, the molar concentration of the sodium hydroxide solution is 5~15 mol / L, for example, it can be 5 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, 10 mol / L, 11 mol / L, 12 mol / L, 13 mol / L, 14 mol / L or 15 mol / L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] Preferably, the base solution is an industrial-grade ferrous sulfate solution.

[0019] Preferably, the iron concentration in the base solution is 1.0~1.2 mol / L, for example, it can be 1.0 mol / L, 1.03 mol / L, 1.05 mol / L, 1.07 mol / L, 1.09 mol / L, 1.12 mol / L, 1.14 mol / L, 1.16 mol / L, 1.18 mol / L or 1.2 mol / L, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] Preferably, the concentration of titanium in the base solution is 0.05~0.06 mol / L, for example, it can be 0.050 mol / L, 0.051 mol / L, 0.052 mol / L, 0.053 mol / L, 0.054 mol / L, 0.055 mol / L, 0.056 mol / L, 0.057 mol / L, 0.058 mol / L, 0.059 mol / L or 0.060 mol / L, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] The present invention preferably uses titanium concentration in the substrate within the above-mentioned range, which can ensure the titanium doping amount while taking into account the uniformity of titanium doping.

[0022] Preferably, the molar ratio of the total amount of phosphorus in the sodium phosphate and sodium pyrophosphate added in the coprecipitation reaction to the molar ratio of ferrous ions in the base solution is 1.33 to 1.43, for example, 1.33, 1.34, 1.35, 1.36, 1.37, 1.38, 1.39, 1.4, 1.41, 1.42 or 1.43, etc., but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] The present invention preferably controls the molar ratio of the total amount of phosphorus in the added sodium phosphate and sodium pyrophosphate to the ferrous ions in the bottom solution within the above-mentioned range, which can obtain a cathode material with better rate performance.

[0024] Preferably, the molar ratio of H2O2 to ferrous sulfate in the bottom solution in the coprecipitation reaction is 0.2 to 0.6, for example, it can be 0.2, 0.25, 0.29, 0.34, 0.38, 0.43, 0.47, 0.52, 0.56 or 0.6, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0025] Preferably, the protective atmosphere includes a nitrogen atmosphere.

[0026] Preferably, the pH range in the coprecipitation reaction is maintained at 4 to 8, for example, 4, 4.5, 4.9, 5.4, 5.8, 6.3, 6.7, 7.2, 7.6 or 8, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0027] This invention maintains a pH range of 4-8 during the coprecipitation reaction, resulting in a better coprecipitation effect, a more uniform elemental distribution in the obtained material, and fewer impurities after calcination.

[0028] Preferably, the coprecipitation reaction time is 30-50 hours, for example, 30 hours, 33 hours, 35 hours, 37 hours, 39 hours, 42 hours, 44 hours, 46 hours, 48 ​​hours or 50 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0029] Preferably, the temperature of the coprecipitation reaction is 30~90℃, for example, it can be 30℃, 37℃, 44℃, 50℃, 57℃, 64℃, 70℃, 77℃, 84℃ or 90℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0030] Preferably, the preparation method further includes: washing and drying the reactants of the co-precipitation reaction sequentially to obtain the titanium-doped NFPP cathode material precursor.

[0031] In a second aspect, the present invention provides a titanium-doped NFPP cathode material precursor, wherein the titanium-doped NFPP cathode material precursor is prepared by the preparation method of the titanium-doped NFPP cathode material precursor described in the first aspect.

[0032] In this invention, the titanium-doped NFPP cathode material precursor has an amorphous structure.

[0033] Preferably, the titanium doping amount in the titanium-doped NFPP cathode material precursor is 1.0~1.2wt%, for example, it can be 1.0wt%, 1.02wt%, 1.05wt%, 1.08wt%, 1.1wt%, 1.12wt%, 1.15wt%, 1.18wt%, or 1.2wt%, etc.

[0034] Thirdly, the present invention provides a method for preparing a titanium-doped NFPP cathode material, the method comprising: mixing sodium carbonate with the titanium-doped NFPP cathode material precursor described in the second aspect, and wet milling to obtain a first material; spray granulating the first material to obtain granulated particles; and sintering the granulated particles to obtain the titanium-doped NFPP cathode material.

[0035] The titanium-doped NFPP cathode material precursor provided by this invention can be mixed with sodium carbonate, wet-milled, spray-granulated, and sintered to obtain a titanium-doped NFPP cathode material with excellent rate performance.

[0036] The present invention first performs spray granulation and then sintering, which can improve the morphology of titanium-doped NFPP cathode material, thereby further improving the rate performance of titanium-doped NFPP cathode material.

[0037] Preferably, the molar ratio of sodium carbonate to titanium-doped NFPP cathode material precursor is (2.0~2.5):1, for example, it can be 2.0:1, 2.06:1, 2.12:1, 2.17:1, 2.23:1, 2.28:1, 2.34:1, 2.39:1, 2.45:1 or 2.5:1, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] The present invention preferably controls the molar ratio of sodium carbonate to titanium-doped NFPP cathode material precursor within the above-mentioned range, which has better rate performance.

[0039] Preferably, the wet sanding time is 2 to 6 hours, for example, it can be 2 hours, 2.5 hours, 2.9 hours, 3.4 hours, 3.8 hours, 4.3 hours, 4.7 hours, 5.2 hours, 5.6 hours or 6 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0040] Preferably, the rotational speed of the wet sand mill is 100~200 r / min, for example, it can be 100 r / min, 112 r / min, 123 r / min, 134 r / min, 145 r / min, 156 r / min, 167 r / min, 178 r / min, 189 r / min or 200 r / min, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0041] Preferably, the spray granulation temperature is 200~250℃, for example, it can be 200℃, 210℃, 220℃, 230℃, 240℃ or 250℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] Preferably, the sintering is carried out in a nitrogen atmosphere.

[0043] Preferably, the protective atmosphere includes a nitrogen atmosphere.

[0044] Preferably, the sintering temperature is 550~650℃, for example, it can be 550℃, 562℃, 573℃, 584℃, 595℃, 606℃, 617℃, 628℃, 639℃ or 650℃, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0045] The present invention preferably controls the sintering temperature within the above-mentioned range, resulting in a cathode material with a lower impurity phase content.

[0046] Preferably, the sintering time is 6 to 12 hours, for example, it can be 6 hours, 6.7 hours, 7.4 hours, 8 hours, 8.7 hours, 9.4 hours, 10 hours, 10.7 hours, 11.4 hours or 12 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] Fourthly, the present invention provides a titanium-doped NFPP cathode material, wherein the titanium-doped NFPP cathode material is obtained by the preparation method of the titanium-doped NFPP cathode material described in the third aspect.

[0048] Preferably, the particle size D50 of the titanium-doped NFPP cathode material is 10~25μm, for example, it can be 10μm, 12μm, 13μm, 14μm, 15μm, 20μm, 22μm or 25μm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0049] Fifthly, the present invention provides a sodium-ion battery, the sodium-ion battery comprising the titanium-doped NFPP cathode material described in the fourth aspect.

[0050] Compared with the prior art, the present invention has at least the following beneficial effects:

[0051] (1) The method for preparing titanium-doped NFPP cathode material precursor provided by the present invention improves the rate performance of cathode material by doping with a small amount of titanium element, wherein the 1C / 0.1C discharge capacity ratio is above 95.44% under preferred conditions;

[0052] (2) The method for preparing titanium-doped NFPP cathode material precursor provided by the present invention preferably uses industrial-grade ferrous sulfate solution directly as the base liquid, which reduces the production cost and can be applied in large-scale commercial applications;

[0053] (3) The method for preparing titanium-doped NFPP cathode material precursor provided by the present invention is prepared by co-precipitation, which does not require the addition of complexing agents or other organic substances, and is simple to operate and has a short process.

[0054] (4) The titanium-doped NFPP cathode material provided by the present invention has excellent rate performance, and the sodium-ion battery finally prepared can be applied to the field of low power. Detailed Implementation

[0055] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0056] It should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0057] Example 1

[0058] This embodiment provides a method for preparing a titanium-doped NFPP cathode material precursor, the method comprising the following steps:

[0059] (1) Sodium phosphate, sodium pyrophosphate and water are mixed to form solution A; the molar concentration of sodium phosphate in solution A is 0.3 mol / L and the molar concentration of sodium pyrophosphate is 0.2 mol / L.

[0060] (2) Solution A, hydrogen peroxide with a molar concentration of 12 mol / L, and sodium hydroxide solution with a molar concentration of 10 mol / L were passed into a base solution containing ferrous sulfate and titanium ions (an industrial-grade ferrous sulfate solution with an iron concentration of 1.0 mol / L and a titanium concentration of 0.05 mol / L was prepared as the base solution). A co-precipitation reaction was carried out at 60°C for 40 h under a nitrogen atmosphere. The pH range was maintained at 6.0~7.0 during the co-precipitation reaction. The molar ratio of the total amount of phosphorus in the sodium phosphate and sodium pyrophosphate added to the ferrous ions in the base solution was 1.38, and the molar ratio of H2O2 to ferrous sulfate in the base solution was 0.3. After the co-precipitation reaction was completed, the reactants were washed and dried sequentially to obtain the titanium-doped NFPP cathode material precursor. The titanium doping content in the titanium-doped NFPP cathode material precursor was 1.1 wt%.

[0061] Example 2

[0062] This embodiment provides a method for preparing a titanium-doped NFPP cathode material precursor, the method comprising the following steps:

[0063] (1) Mix sodium phosphate, sodium pyrophosphate and water to form solution A; the molar concentration of sodium phosphate in solution A is 0.1 mol / L and the molar concentration of sodium pyrophosphate is 0.1 mol / L.

[0064] (2) Solution A, hydrogen peroxide with a molar concentration of 15 mol / L, and sodium hydroxide solution with a molar concentration of 15 mol / L were passed into a base solution containing ferrous sulfate and titanium ions (an industrial-grade ferrous sulfate solution with an iron concentration of 1.2 mol / L and a titanium concentration of 0.06 mol / L was prepared as the base solution), and a co-precipitation reaction was carried out at 90°C for 30 h under a nitrogen atmosphere. The pH range during the co-precipitation reaction was maintained at 4.0~5.0. The molar ratio of the total amount of phosphorus in the sodium phosphate and sodium pyrophosphate added to the ferrous ions in the base solution was 1.33, and the molar ratio of H2O2 to ferrous sulfate in the base solution was 0.2. After the co-precipitation reaction was completed, the reactants were washed and dried sequentially to obtain the titanium-doped NFPP cathode material precursor. The titanium doping amount in the titanium-doped NFPP cathode material precursor was 1.2 wt%.

[0065] Example 3

[0066] This embodiment provides a method for preparing a titanium-doped NFPP cathode material precursor, the method comprising the following steps:

[0067] (1) Mix sodium phosphate, sodium pyrophosphate and water to form solution A; the molar concentration of sodium phosphate in solution A is 2 mol / L and the molar concentration of sodium pyrophosphate is 2 mol / L.

[0068] (2) Solution A, hydrogen peroxide with a molar concentration of 5 mol / L, and sodium hydroxide solution with a molar concentration of 5 mol / L were passed into a base solution containing ferrous sulfate and titanium ions (an industrial-grade ferrous sulfate solution with an iron concentration of 1.0 mol / L and a titanium concentration of 0.05 mol / L was prepared as the base solution), and a co-precipitation reaction was carried out at 30°C for 50 h under a nitrogen atmosphere. The pH range during the co-precipitation reaction was maintained at 7.0~8.0. The molar ratio of the total amount of phosphorus in the sodium phosphate and sodium pyrophosphate added to the ferrous ions in the base solution was 1.43, and the molar ratio of H2O2 to ferrous sulfate in the base solution was 0.6. After the co-precipitation reaction was completed, the reactants were washed and dried sequentially to obtain the titanium-doped NFPP cathode material precursor. The titanium doping amount in the titanium-doped NFPP cathode material precursor was 1.0 wt%.

[0069] Example 4

[0070] This embodiment provides a method for preparing a titanium-doped NFPP cathode material precursor. Except for maintaining the pH range of 3.0 to 3.8 in the co-precipitation reaction, the preparation method is the same as in Example 1, and will not be repeated here.

[0071] Example 5

[0072] This embodiment provides a method for preparing a titanium-doped NFPP cathode material precursor. Except for maintaining the pH range of 8.2 to 9.0 in the co-precipitation reaction, the preparation method is the same as in Example 1, and will not be repeated here.

[0073] Example 6

[0074] This embodiment provides a method for preparing a titanium-doped NFPP cathode material precursor. The preparation method is the same as in Example 1, except that the concentration of titanium in the substrate is 0.03 mol / L, and will not be repeated here.

[0075] Example 7

[0076] This embodiment provides a method for preparing a titanium-doped NFPP cathode material precursor. The preparation method is the same as in Example 1, except that the concentration of titanium in the substrate is 0.08 mol / L, and will not be repeated here.

[0077] Comparative Example 1

[0078] This comparative example provides a titanium-doped NFPP cathode material, which is Example 1 of CN120364666A.

[0079] Application Example 1

[0080] This application example provides a method for preparing a titanium-doped NFPP cathode material, the method comprising the following steps:

[0081] Sodium carbonate was mixed with the titanium-doped NFPP cathode material precursor described in Example 1 at a molar ratio of 2.2:1, and then wet-milled at 150 r / min for 4 h to obtain the first material; the first material was spray-granulated at 220 °C to obtain granulated particles; the granulated particles were sintered at 600 °C for 8 h in a nitrogen atmosphere to obtain the titanium-doped NFPP cathode material.

[0082] Application Example 2

[0083] This application example provides a method for preparing a titanium-doped NFPP cathode material, the method comprising the following steps:

[0084] Sodium carbonate was mixed with the titanium-doped NFPP cathode material precursor described in Example 2 at a molar ratio of 2.0:1, and then wet-milled at 100 r / min for 6 h to obtain the first material; the first material was spray-granulated at 250 °C to obtain granulated particles; the granulated particles were sintered at 650 °C for 6 h in a nitrogen atmosphere to obtain the titanium-doped NFPP cathode material.

[0085] Application Example 3

[0086] This application example provides a method for preparing a titanium-doped NFPP cathode material, the method comprising the following steps:

[0087] Sodium carbonate was mixed with the titanium-doped NFPP cathode material precursor described in Example 3 at a molar ratio of 2.5:1, and then wet-milled at 200 r / min for 2 h to obtain the first material; the first material was spray-granulated at 200 °C to obtain granulated particles; the granulated particles were sintered at 550 °C for 12 h in a nitrogen atmosphere to obtain the titanium-doped NFPP cathode material.

[0088] Application Examples 4-7 and Comparative Example 1

[0089] Application Examples 4-7 and Comparative Example 1 provide a method for preparing titanium-doped NFPP cathode material. Except for the preparation methods of titanium-doped NFPP cathode material precursors in Examples 4-7 and Comparative Example 1, the preparation methods are the same as in Application Example 1, and will not be repeated here.

[0090] Application Example 8

[0091] This application example provides a method for preparing a titanium-doped NFPP cathode material. The preparation method is the same as that in Application Example 1, except that the sintering temperature is 500°C.

[0092] Application Example 9

[0093] This application example provides a method for preparing a titanium-doped NFPP cathode material. The preparation method is the same as that in Application Example 1, except that the sintering temperature is 700°C.

[0094] Application Example 10

[0095] This application example provides a method for preparing titanium-doped NFPP cathode material. The preparation method is the same as that in Application Example 1, except that spray granulation is not performed and sintering is performed directly.

[0096] At 25°C, using the above-prepared positive electrode material as the main positive electrode material and a sodium metal sheet as the negative electrode, CR2032 coin cells were assembled. Then, within a voltage range of 2.0–3.6V, the discharge current densities were 10 mA·g⁻¹. -1 and 100mA·g -1 Electrochemical performance tests were then conducted.

[0097] The test results of the above embodiments and comparative examples are shown in Table 1.

[0098] Table 1

[0099]

[0100] As can be seen from Table 1:

[0101] As can be seen from the combined application examples 1-3, the titanium-doped NFPP cathode material provided by this invention, after being used to form a coin cell, can significantly improve the rate performance, with a 1C / 0.1C discharge capacity ratio of over 95.44%, and a 10 mA·g discharge capacity of over 95.44%. -1 Discharge capacity is above 105.3 mAh / g, 100 mA·g -1 The discharge capacity is above 100.5 mAh / g.

[0102] Comparing Application Example 1 with Application Examples 4-5, it can be seen that the pH range maintained in the co-precipitation reaction of Application Example 1 is 6.0-7.0, compared to 3.0-3.8 and 8.2-9.0 in Application Examples 4-5, respectively. The 1C / 0.1C discharge capacity ratio in Application Example 1 is 95.75%, while in Application Examples 4-5 it is 93.40% and 90.12%, respectively. This shows that the present invention controls the pH range of the co-precipitation reaction within a reasonable range, which can better improve the rate performance of the cathode material.

[0103] Comparing Application Example 1 with Application Examples 6-7, it can be seen that the concentration of titanium in the substrate in Application Example 1 is 0.05 mol / L, compared to 0.03 mol / L and 0.08 mol / L in Application Examples 6-7, respectively. The 1C / 0.1C discharge capacity ratio in Application Example 1 is 95.75%, while it is 92.51% and 90.12% in Application Examples 6-7, respectively. This shows that by controlling the concentration of titanium in the substrate within a reasonable range, the present invention can better improve the rate performance of the cathode material.

[0104] Comparing Application Example 1 with Application Examples 8-9, it can be seen that the calcination temperature affects the performance of the cathode material after sintering. Selecting a suitable calcination temperature can further improve the rate performance.

[0105] The present invention has been illustrated with the above embodiments to illustrate its detailed features, but the present invention is not limited to the above detailed features, that is, it does not mean that the present invention must rely on the above detailed features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the selected technical features, additions of auxiliary technical features, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a titanium-doped NFPP cathode material precursor, characterized in that, The preparation method includes the following steps: (1) Mix sodium phosphate, sodium pyrophosphate and the first solvent to form solution A; (2) Solution A, hydrogen peroxide and sodium hydroxide solution are passed into a bottom liquid containing ferrous sulfate and titanium ions, and a co-precipitation reaction is carried out in a protective atmosphere to prepare a titanium-doped NFPP cathode material precursor.

2. The preparation method according to claim 1, characterized in that, The molar concentration of sodium phosphate in solution A in step (1) is 0.1~2 mol / L; Preferably, the molar concentration of sodium pyrophosphate in solution A is 0.1~2 mol / L.

3. The preparation method according to claim 1 or 2, characterized in that, The molar concentration of the hydrogen peroxide is 5~15 mol / L; Preferably, the molar concentration of the sodium hydroxide solution is 5~15 mol / L; Preferably, the base solution is an industrial-grade ferrous sulfate solution; Preferably, the iron concentration in the bottom solution is 1.0~1.2 mol / L; Preferably, the concentration of titanium in the bottom solution is 0.05~0.06 mol / L.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The total amount of phosphorus in the sodium phosphate and sodium pyrophosphate added in the coprecipitation reaction is 1.33 to 1.43 molar ratio of phosphorus to ferrous ions in the bottom solution. Preferably, the molar ratio of H2O2 to ferrous sulfate in the bottom solution during the coprecipitation reaction is 0.2 to 0.

6.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The protective atmosphere includes a nitrogen atmosphere; Preferably, the pH range in the coprecipitation reaction is maintained at 4-8; Preferably, the coprecipitation reaction takes 30-50 hours; Preferably, the temperature of the co-precipitation reaction is 30~90℃; Preferably, the preparation method further includes: washing and drying the reactants of the co-precipitation reaction sequentially to obtain the titanium-doped NFPP cathode material precursor.

6. A titanium-doped NFPP cathode material precursor, characterized in that, The titanium-doped NFPP cathode material precursor is prepared by the preparation method of titanium-doped NFPP cathode material precursor according to any one of claims 1 to 5.

7. A method for preparing a titanium-doped NFPP cathode material, characterized in that, The preparation method includes: mixing sodium carbonate with the titanium-doped NFPP cathode material precursor of claim 6, and wet milling to obtain a first material; spray granulation of the first material to obtain granulated particles; and sintering the granulated particles to obtain the titanium-doped NFPP cathode material.

8. The preparation method according to claim 7, characterized in that, The molar ratio of sodium carbonate to titanium-doped NFPP cathode material precursor is (2.0~2.5):1; Preferably, the wet sand milling time is 2-6 hours; Preferably, the rotational speed of the wet sand mill is 100~200 r / min; Preferably, the spray granulation temperature is 200~250℃; Preferably, the sintering is carried out in a nitrogen atmosphere; Preferably, the sintering temperature is 550~650℃; Preferably, the sintering time is 6 to 12 hours.

9. A titanium-doped NFPP cathode material, characterized in that, The titanium-doped NFPP cathode material is obtained using the preparation method of titanium-doped NFPP cathode material as described in claim 7 or 8.

10. A sodium-ion battery, characterized in that, The sodium-ion battery includes the titanium-doped NFPP cathode material as described in claim 9.

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