Sodium-ion battery positive electrode material precursor and preparation method thereof, sodium-ion battery positive electrode material, sodium-ion battery and electric equipment

Abstract

The invention relates to the technical field of sodium-ion batteries, and discloses a sodium-ion battery positive electrode material precursor and a preparation method thereof, a sodium-ion battery positive electrode material, a sodium-ion battery and electric equipment. In an XRD pattern of the positive electrode material precursor, a peak and a steamed bun peak are contained in a range of a diffraction angle 2 theta of 15-25 degrees, and the ratio of the peak area of the peak to the peak area of the steamed bun peak is 0.5-1.5. The positive electrode material precursor provided by the invention has a certain crystalline and amorphous structure, on one hand, relatively high structural order can be ensured, and sodium ion transmission and capacity maintenance are facilitated; on the other hand, stress in the charging and discharging process can be absorbed, and product stability is maintained. When the positive electrode material precursor provided by the invention is applied to the sodium-ion battery, the obtained sodium-ion battery has high capacity and excellent cycle performance at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion batteries, and in particular to a sodium ion battery positive electrode material precursor and a preparation method thereof, a sodium ion battery positive electrode material, a sodium ion battery, and electrical equipment. Background Art

[0002] Sodium-ion batteries have a wide range of raw material sources and low costs, so related research has developed rapidly in recent years.

[0003] The cycling stability and capacity of sodium-ion batteries are crucially dependent on the preparation of cathode materials. To address issues such as low capacity and poor cycling performance, modifications such as doping, coating, specific morphology, and specialized internal structures are commonly employed. However, these cathode material precursors and cathode materials often present complex preparation processes, increasing costs, and difficulties in mass production.

[0004] Therefore, it is of great significance to provide a sodium ion positive electrode material precursor with good electrochemical performance. Summary of the Invention

[0005] The purpose of the present invention is to provide a sodium ion battery positive electrode material precursor and a preparation method thereof, a sodium ion battery positive electrode material, a sodium ion battery and electrical-related equipment, aiming to solve at least one of the above-mentioned technical problems in the prior art.

[0006] In order to achieve the above-mentioned objectives, the first aspect of the present invention provides a sodium ion battery positive electrode material precursor, wherein the XRD spectrum of the positive electrode material precursor contains a sharp peak and a steamed bun peak within a diffraction angle 2θ range of 15-25°, and the ratio of the peak area of the sharp peak to the peak area of the steamed bun peak is 0.5-1.5.

[0007] Preferably, the peak intensity I of the (100) crystal plane of the positive electrode material precursor is (100) Peak intensity I with (001) crystal plane (001) The ratio I (100) / I (001) is 1.2-2.6; optionally, the I (100) / I (001) It is 1.2-2.0.

[0008] Preferably, the chemical formula of the positive electrode material precursor is Ni x Mn y Fe z M 1-x-y-z (OH)2, wherein 0.2≤x≤0.6, 0.3≤y≤0.5, 0.2≤z≤0.5, and M is selected from at least one of Zn, Mg, Ca, Cu, Al, and Zr.

[0009] According to a preferred embodiment, the cathode material precursor satisfies one or more of the following conditions:

[0010] a. The D50 of the cathode material precursor is 8 μm-15 μm, preferably 9 μm-11 μm;

[0011] b. The primary particles on the surface of the positive electrode material precursor are in the form of thin flakes;

[0012] c. The length of the primary particles on the surface of the positive electrode material precursor is 500-2000 nm, preferably 800-1100 nm;

[0013] d. The width of the primary particles on the surface of the positive electrode material precursor is 50-200 nm, preferably 70-90 nm;

[0014] e. The tap density of the positive electrode material precursor is 1.8 to 2.2 g / m 3 , preferably 1.9 to 2.2 g / m 3 , more preferably 2.0 to 2.2 g / m 3 .

[0015] A second aspect of the present invention provides a method for preparing the positive electrode material precursor as described in the first aspect, the method comprising the following steps:

[0016] mixing water, a precipitant solution, and a complexing agent solution to obtain a base solution;

[0017] In a gas phase atmosphere, the metal salt solution, the precipitant solution and the complexing agent solution are introduced into the base liquid to perform a co-precipitation reaction until the slurry reaches a preset particle size;

[0018] performing solid-liquid separation, alkali washing and drying on the slurry to obtain the positive electrode material precursor;

[0019] The drying temperature is less than 140°C.

[0020] Preferably, the preparation method satisfies at least one of the following conditions:

[0021] (1) The coprecipitation reaction is divided into a first stage and a second stage, wherein the volume content of oxygen in the gaseous atmosphere of the first stage is ≤0.5%, and the volume content of oxygen in the gaseous atmosphere of the second stage is 0.7-1.1%;

[0022] (2) The metal salt solution contains Ni, Fe, Mn elements and a doping element M;

[0023] (3) The sum of the concentrations of metal ions in the metal salt solution is 1.5-2.5 mol / L;

[0024] (4) The precipitant solution is a sodium hydroxide solution;

[0025] (5) The concentration of the precipitant solution is 8-12 mol / L;

[0026] (6) The complexing agent solution is an ammonia solution;

[0027] (7) The concentration of the complexing agent solution is 10-12 mol / L.

[0028] According to a preferred embodiment, the preparation method satisfies at least one of the following conditions:

[0029] A. The metal salt solution further comprises sulfuric acid, wherein the concentration of the sulfuric acid in the metal salt solution is 0.01-0.03 mol / L;

[0030] B. The pH value of the base solution is 10.20-10.70;

[0031] C. The mass concentration of ammonia water in the base liquid is 3.5-4.0 g / L;

[0032] D. The mass concentration of ammonia in the coprecipitation reaction system is 3.5-4.0 g / L;

[0033] E. The pH value of the coprecipitation reaction is 10.20-10.70;

[0034] F. The temperature of the coprecipitation reaction is 40-60°C;

[0035] G. The stirring speed of the coprecipitation reaction is 100-400 rpm; preferably, the initial stirring speed of the coprecipitation reaction is 310-330 rpm. When the D50 of the slurry is 4.8-5.2 μm, the stirring speed is reduced to 290-310 rpm. The stirring speed is reduced once every time the D50 of the subsequent slurry increases by 0.4-0.6 μm, with each reduction of 18-22 rpm;

[0036] H, the alkali cleaning adopts the sodium hydroxide solution with a concentration of 1-2mol / L to carry out;

[0037] I. The drying temperature is 100-120°C;

[0038] J. The first stage is the coprecipitation reaction until the D50 of the slurry is 5 to 9 μm;

[0039] K. The oxygen content in the gaseous atmosphere of the second stage is adjusted by introducing air.

[0040] A third aspect of the present invention provides a sodium ion battery positive electrode material, wherein the raw material of the sodium ion battery positive electrode material includes the sodium ion battery positive electrode material precursor as described in the first aspect or the sodium ion battery positive electrode material precursor prepared by the preparation method as described in the second aspect.

[0041] A fourth aspect of the present invention provides a sodium ion battery, comprising the sodium ion battery positive electrode material as described in the third aspect.

[0042] The fifth aspect of the present invention provides an electrical device, comprising the sodium ion battery as described in the fourth aspect.

[0043] Compared with the prior art, the technical solution provided by the present invention has at least the following advantages:

[0044] The diffraction angle 2θ contains a sharp peak and a bun peak in the range of 15-25°, indicating that the positive electrode material precursor provided by the present invention coexists in a crystalline state and an amorphous state, and the ratio of the peak area of the sharp peak to the peak area of the bun peak is 0.5-1.5. The crystalline state in the precursor material at this ratio can ensure a high structural order, which is beneficial to the transport of sodium ions, thereby improving the capacity of the sodium ion battery. At the same time, part of the amorphous state has a disordered atomic arrangement, which can absorb the stress during the charge and discharge process, maintain the stability of the material, and thus improve the cycle performance of the sodium ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a scanning electron microscope image of the cathode material precursor prepared in Example 1 of the present invention;

[0046] Figure 2 is the X-ray diffraction pattern of the cathode material precursor prepared in Example 1 of the present invention;

[0047] Figure 3 is the X-ray diffraction pattern of the cathode material precursor prepared in Example 2 of the present invention;

[0048] Figure 4 This is the X-ray diffraction pattern of the positive electrode material precursor prepared in Comparative Example 1 of the present invention;

[0049] Figure 5 This is the X-ray diffraction pattern of the cathode material precursor prepared in Comparative Example 2 of the present invention;

[0050] Figure 6 This is the X-ray diffraction pattern of the positive electrode material precursor prepared in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0051] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0052] It should be noted that, in various aspects of the present invention, for the same components or terms in various aspects, the present invention is only described once in one aspect without repeated description, which should not be understood by those skilled in the art as a limitation of the present invention.

[0053] As used herein:

[0054] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0055] The conjunction "consisting of" excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed, excluding materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim, rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0056] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed alone. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range.

[0057] In these examples, parts and percentages are by mass unless otherwise indicated.

[0058] "Parts by mass" refers to the basic unit of measurement used to express the mass ratio of multiple components. One part can represent any unit of mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, this means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, we could say that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number representing a multiplication factor). It's important to note that, unlike parts by mass, the sum of the mass of all components is not limited to 100 parts.

[0059] "And / or" is used to indicate that one or both of the described situations may occur. For example, A and / or B includes (A and B) and (A or B). It should be clarified that the description of "thin sheet" in the present invention specifically refers to the morphological characteristics of the corresponding structure in the positive electrode material precursor and should not be understood as a specific quantification.

[0060] In the present invention, the morphology of the cathode material precursor is characterized by scanning electron microscopy (SEM).

[0061] In the present invention, D50 refers to the particle size corresponding to when the cumulative particle size volume distribution percentage of the positive electrode material precursor reaches 50%.

[0062] As mentioned above, the first aspect of the present invention provides a sodium ion battery positive electrode material precursor, wherein the XRD spectrum of the positive electrode material precursor contains a sharp peak and a steamed bun peak in the diffraction angle 2θ range of 15-25°, and the ratio of the peak area of the sharp peak to the peak area of the steamed bun peak is 0.5-1.5.

[0063] The peak areas of the sharp peak and the bun peak in the present invention were processed using the jade software and obtained by manual quadratic function fitting, specifically:

[0064] 1. Separation of overlapping peaks: First, separate the peaks using the Peak Deconvolution tool in the Jade software;

[0065] 2. Data processing: a) Smoothing: Click Analyze → Smooth in the menu bar and select appropriate smoothing parameters to reduce noise interference; b) Background subtraction: Click Analyze → Background to enter the background subtraction interface, select FitBackground, select Polynomial in "Fit Type", and set the degree to 2 (i.e., quadratic function). Adjust the background baseline nodes to ensure that the background fitting line fits the data baseline, and click Subtract to subtract the background;

[0066] 3. Manual peak fitting

[0067] a) Select the peak region: Use the Zoom tool on the toolbar to zoom in on the target peak region, and click Peak Fit → FitPeaks to enter the peak fitting interface.

[0068] b) Define the peak range: Use the mouse to drag and select the peak range (left and right boundaries) to be fitted, ensuring that the baselines on both sides of the peak are flat and avoiding overlapping peaks.

[0069] c) Set the fitting function: In the peak fitting interface, select Fit Function as Polynomial and set the degree to 2 (quadratic function) or use the Manual Fit mode to manually adjust the peak parameters (height, position, width).

[0070] d) Adjust fitting parameters: Adjust the quadratic function parameters by dragging the fitting curve nodes or entering numerical values to make the fitting curve best match the experimental peak shape. Observe the residual curve to ensure that the fitting error is minimized.

[0071] 4. Calculate peak area

[0072] a) Integrate peak area: After completing the fitting, the software will automatically calculate and display the peak area (Area). Record the results: Click Report → Peak Report to generate a report and view the peak area value.

[0073] b) Calculate the ratio of the peak areas.

[0074] The present invention controls the ratio of the peak area of the sharp peak of the positive electrode material precursor in the diffraction angle 2θ range of 15-25° to the peak area of the bun peak within the above-mentioned specific range (0.5-1.5). The positive electrode material precursor can ensure a high structural order, which is beneficial to sodium ion transmission and capacity retention. At the same time, it has a partially disordered atomic arrangement. When the positive electrode material precursor is applied to a sodium ion battery, it can absorb the stress during the charge and discharge process, maintain the stability of the product, and thus improve the cycle performance of the sodium ion battery.

[0075] In some embodiments, the peak intensity I of the (100) crystal plane of the positive electrode material precursor is (100) Peak intensity I with (001) crystal plane (001) The ratio I (100) / I (001) 1.2-2.6, for example, any value between 1.2-1.3, 1.3-1.4, 1.4-1.5, 1.5-1.6, 1.6-1.7, 1.7-1.8, 1.8-1.9, 1.9-2.0, 2.0-2.1, 2.1-2.2, 2.2-2.3, 2.3-2.4, 2.4-2.5 or 2.5-2.6;

[0076] Optionally, the I (100) / I (001) It is 1.2-2.0.

[0077] In some embodiments of the present invention, the peak intensity I (100) Peak intensity I with (001) crystal plane (001) The ratio I (100) / I (001) Within the range of 1.2-2.6, the obtained positive electrode material can maintain a good layered structure and be applied to sodium ion batteries, so that the sodium ion batteries can have both good capacity and cycle performance.

[0078] In some embodiments, the chemical formula of the cathode material precursor is Ni x Mn y Fe z M 1-x-y-z (OH)2, wherein 0.2≤x≤0.6, 0.3≤y≤0.5, 0.2≤z≤0.5, and M is selected from at least one of Zn, Mg, Ca, Cu, Al, and Zr.

[0079] In some embodiments, the D50 of the cathode material precursor is 8 μm-15 μm, for example, 8 μm, 9 μm, 10 μm, 12 μm, 14 μm, 15 μm, or any value between 8 μm and 15 μm;

[0080] Optionally, the D50 of the positive electrode material precursor is 9 μm-11 μm.

[0081] In some embodiments of the present invention, the D50 of the cathode material precursor is in the range of 8 μm-15 μm, which is beneficial to improving the tap density of the cathode material and thus improving the energy density.

[0082] In some embodiments, the primary particles on the surface of the positive electrode material precursor are in the form of flakes.

[0083] In some embodiments, the length of the primary particles on the surface of the positive electrode material precursor is 500 to 2000 nm, for example, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1100 nm, 1200 nm, 1300 nm, 1400 nm, 1500 nm, 1600 nm, 1700 nm, 1800 nm, 1900 nm, 2000 nm or any value between 500 and 2000 nm;

[0084] Optionally, the length of the primary particles on the surface of the positive electrode material precursor is 800 to 1100 nm;

[0085] In some embodiments, the width of the primary particles on the surface of the positive electrode material precursor is 50 to 200 nm, for example, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, or any value between 50 and 200 nm;

[0086] Optionally, the width of the primary particles on the surface of the positive electrode material precursor is 70 to 90 nm.

[0087] In some embodiments of the present invention, the flaky primary particles on the surface of the positive electrode material precursor are beneficial to increasing the number of micropores, improving the contact area between the electrolyte and the material, and thus improving the capacity.

[0088] In some embodiments, the tap density of the cathode material precursor is 1.8 to 2.2 g / m 3 , for example, it can be 1.8g / m 3 , 1.9g / m 3 , 2.0g / m 3 , 2.1g / m 3 , 2.2g / m 3 or 1.8-2.2 g / m 3 Any value between

[0089] Optionally, the tap density of the positive electrode material precursor is 1.9 to 2.2 g / m 3 , further optional 2.0~2.2g / m 3 .

[0090] As mentioned above, the second aspect of the present invention provides a method for preparing the positive electrode material precursor as described in the first aspect, the method comprising the following steps:

[0091] mixing water, a precipitant solution, and a complexing agent solution to obtain a base solution;

[0092] In a gas phase atmosphere, the metal salt solution, the precipitant solution and the complexing agent solution are introduced into the base liquid to perform a co-precipitation reaction until the slurry reaches a preset particle size;

[0093] performing solid-liquid separation, alkali washing and drying on the slurry to obtain the positive electrode material precursor;

[0094] The drying temperature is less than 140°C.

[0095] In some embodiments, the coprecipitation reaction is carried out in a reactor.

[0096] In some embodiments, the coprecipitation reaction is divided into a first stage and a second stage, and the volume content of oxygen in the gaseous atmosphere of the first stage is ≤0.5%, for example, the volume content of oxygen is ≤0.4%, the volume content of oxygen is ≤0.3%, the volume content of oxygen is ≤0.2%, and the volume content of oxygen is ≤0.1%; the volume content of oxygen in the gaseous atmosphere of the second stage is 0.7-1.1%, for example, it can be 0.7%, 0.8%, 0.9%, 1.0%, 1.1% or any value between 0.7-1.1%.

[0097] In some embodiments, the oxygen content in the gaseous atmosphere of the first stage is adjusted by introducing an inert gas, illustratively nitrogen.

[0098] In some embodiments, the oxygen content in the gaseous atmosphere of the second stage is adjusted by introducing air.

[0099] In some embodiments, the metal salt solution contains Ni, Fe, Mn elements and a doping element M.

[0100] In some embodiments, the sum of the concentrations of metal ions in the metal salt solution is 1.5-2.5 mol / L, for example, 1.5 mol / L, 1.8 mol / L, 2.0 mol / L, 2.5 mol / L, or any value between 1.5-2.5 mol / L.

[0101] In some embodiments, the precipitant solution is a sodium hydroxide solution.

[0102] In some embodiments, the concentration of the precipitant solution is 8-12 mol / L, for example, 8 mol / L, 10 mol / L, 12 mol / L, or any value between 8-12 mol / L.

[0103] In some embodiments, the complexing agent solution is an aqueous ammonia solution.

[0104] In some embodiments, the concentration of the complexing agent solution is 10-12 mol / L, for example, 10 mol / L, 11 mol / L, 12 mol / L, or any value between 10-12 mol / L.

[0105] In some embodiments, the metal salt solution further includes sulfuric acid, and the concentration of sulfuric acid in the metal salt solution is 0.01-0.03 mol / L, for example, 0.01 mol / L, 0.02 mol / L, 0.03 mol / L or any value between 0.01-0.03 mol / L.

[0106] In some embodiments, the pH value of the base solution is 10.20-10.70, for example, it can be 10.20, 10.30, 10.40, 10.50, 10.60, 10.70 or any value between 10.20 and 10.70.

[0107] In some embodiments, the mass concentration of aqueous ammonia in the base liquid is 3.5-4.0 g / L, for example, it can be 3.5 g / L, 3.6 g / L, 3.7 g / L, 3.8 g / L, 3.9 g / L, 4.0 g / L or any value between 3.5-4.0 g / L.

[0108] In some embodiments, the mass concentration of aqueous ammonia in the coprecipitation reaction system is 3.5-4.0 g / L, for example, it can be 3.5 g / L, 3.6 g / L, 3.7 g / L, 3.8 g / L, 3.9 g / L, 4.0 g / L or any value between 3.5-4.0 g / L.

[0109] In some embodiments, the pH value of the coprecipitation reaction is 10.20-10.70, for example, it can be 10.20, 10.30, 10.40, 10.50, 10.60, 10.70 or any value between 10.20 and 10.70.

[0110] In some embodiments, the coprecipitation reaction temperature is 40-60°C, for example, 40°C, 45°C, 50°C, 55°C, 60°C or any value between 40-60°C.

[0111] In some embodiments, the stirring speed of the coprecipitation reaction is 100-400 rpm, for example, it can be 100 rpm, 200 rpm, 300 rpm, 400 rpm or any value between 100-400 rpm.

[0112] In some embodiments, the initial stirring speed of the coprecipitation reaction is 310-330 rpm. When the D50 of the slurry is 4.8-5.2 μm, the stirring speed is reduced to 290-310 rpm. The stirring speed is subsequently reduced every time the D50 of the slurry increases by 0.4-0.6 μm, with each reduction of 18-22 rpm.

[0113] The inventors of the present invention have found that by controlling the stirring speed within the above range, the D50 distribution of the prepared cathode material precursor is narrow and the sphericity is good.

[0114] In some embodiments, the alkali washing is performed using a sodium hydroxide solution with a concentration of 1-2 mol / L. For example, the concentration of the sodium hydroxide solution can be 1 mol / L, 2 mol / L, or any value between 1-2 mol / L.

[0115] In some embodiments, the alkali washing temperature is 70-80°C, for example, 70°C, 75°C, 80°C or any value between 70-80°C.

[0116] According to a preferred embodiment, the preparation method further comprises: after the alkali washing, water washing.

[0117] In some embodiments, the water washing is performed at 23-35°C.

[0118] The present invention has no special requirements on the type of water, and those skilled in the art can select it as needed. Exemplarily, the water is pure water and / or deionized water.

[0119] In some embodiments, the drying temperature is 100-120°C, for example, 100°C, 110°C, 120°C or any value between 100-120°C.

[0120] In some embodiments, the drying time is 10-12 hours, for example, it can be 10 hours, 11 hours, 12 hours or any value between 10-12 hours.

[0121] In some embodiments, the dry atmosphere is air, oxygen, or an inert gas, and the inert gas is selected from one or more of nitrogen, argon, and helium.

[0122] In some embodiments, the preparation method further comprises: sieving the dried material to obtain a positive electrode material precursor.

[0123] In some embodiments, the first stage is the coprecipitation reaction until the D50 of the slurry is 5-9 μm, for example, the coprecipitation reaction is carried out until the D50 of the slurry is 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or any value between 5 and 9 μm.

[0124] In some embodiments, the oxygen content in the gaseous atmosphere of the second stage is adjusted by introducing air.

[0125] As mentioned above, the third aspect of the present invention provides a sodium ion battery positive electrode material, wherein the raw material of the sodium ion battery positive electrode material includes the sodium ion battery positive electrode material precursor as described in the first aspect or the sodium ion battery positive electrode material precursor prepared by the preparation method described in the second aspect.

[0126] The present invention does not particularly limit the method for preparing a sodium ion battery positive electrode material using the positive electrode material precursor provided by the present invention, and those skilled in the art can select a method based on technical means known in the art. However, in order to obtain a sodium ion battery positive electrode material with better electrochemical performance, the present invention preferably uses the following method to prepare the sodium ion battery positive electrode material.

[0127] According to a preferred embodiment, the method for preparing the sodium ion battery positive electrode material includes:

[0128] uniformly mixing the positive electrode material precursor and the sodium-containing compound to obtain a mixture;

[0129] The mixed material is sintered in an air atmosphere to obtain the sodium ion battery positive electrode material.

[0130] In some embodiments, the sodium-containing compound is sodium carbonate.

[0131] In some embodiments, the sintering is performed in a muffle furnace.

[0132] In some embodiments, the sintering conditions include: heating at a heating rate of 1-1.5°C / min to a temperature of 800-900°C, for example, 800, 820, 850°C, 900°C or any value between 800-900°C; and sintering time of 10-14h, for example, 10h, 11h, 12h, 13h, 14h or any value between 10-14h.

[0133] In the present invention, the sintering time does not include the time required for heating.

[0134] In some embodiments, the molar ratio of the positive electrode material precursor to the sodium-containing compound is 1:1.03-1.05.

[0135] The preparation method of the sodium ion battery positive electrode material of the present invention may also include post-processing means known in the art such as cooling and screening treatment, so as to obtain the sodium ion battery positive electrode material with better quality. The present invention will not be described in detail here, and those skilled in the art should not understand it as a limitation of the present invention.

[0136] As mentioned above, the fourth aspect of the present invention provides a sodium ion battery, comprising the sodium ion battery positive electrode material as described in the third aspect.

[0137] As mentioned above, the fifth aspect of the present invention provides an electrical device, including the sodium ion battery described in the fourth aspect.

[0138] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, the raw materials are all commercially available.

[0139] Example 1

[0140] Prepare a chemical formula Ni 0.33 Mn 0.33 Fe 0.34 The specific preparation method of the sodium ion positive electrode material precursor of (OH)2 is as follows:

[0141] ①Prepare metal salt solution: According to Ni 0.33 Mn 0.33 Fe 0.34 The ratio of nickel, manganese and iron in (OH)2 was as follows: nickel sulfate, ferrous sulfate and manganese sulfate were weighed, and the nickel sulfate, ferrous sulfate and manganese sulfate were dissolved in deionized water to form a metal salt solution with a total metal ion concentration of 2 mol / L. Then, dilute sulfuric acid was added to the metal salt solution. The concentration of sulfuric acid in the metal salt solution was 0.018 mol / L, wherein the dilute sulfuric acid was obtained by mixing 99% concentrated sulfuric acid with pure water at a volume ratio of 1:5;

[0142] ② In the presence of nitrogen, deionized water, a precipitant solution, and a complexing agent solution were added to the reactor and mixed to obtain a base liquid, so that the pH value of the base liquid was 10.30 and the mass concentration of ammonia water in the base liquid was 3.5 g / L; the precipitant solution was a 10.8 mol / L sodium hydroxide solution; and the complexing agent solution was an 11 mol / L ammonia solution.

[0143] ③ nitrogen was introduced into the reactor to control the volume content of oxygen in the gas phase atmosphere to be ≤0.5%, the reaction temperature was raised to 45° C., and the metal salt solution, precipitant solution, and complexing agent solution were introduced into the bottom liquid in the gas phase atmosphere for coprecipitation reaction until the D50 of the slurry was 7 μm. Air was introduced into the reactor to control the volume content of oxygen in the gas phase atmosphere to be 0.7-1.1%. When the D50 of the slurry in the reactor was 9.8 μm, the feeding was stopped;

[0144] The initial stirring speed of the coprecipitation reaction system was 320 rpm. When the D50 of the slurry reached 5.0 μm, the stirring speed was reduced to 300 rpm. The stirring speed was subsequently reduced by 20 rpm each time the D50 of the slurry increased by 0.5 μm.

[0145] The initial flow rate of the metal salt solution is 2 L / h, and the flow rate is increased every 6 hours, with each increase of 2 L / h until it reaches 6 L / h;

[0146] By controlling the flow rates of the precipitant solution and the complexing agent solution, the pH of the liquid phase was maintained at 10.30 and the mass concentration of the ammonia water was 3.5 g / L during the coprecipitation reaction.

[0147] ④ The slurry obtained in step ③ was subjected to solid-liquid separation, and then washed with 75°C, 1.3 mol / L sodium hydroxide solution, and then washed with 25°C deionized water, and then placed in an oven for drying (temperature of 120°C, time of 10h), sieved and sealed after drying to obtain a sodium ion battery positive electrode material precursor.

[0148] Figure 1 The scanning electron microscope image of the cathode material precursor prepared in this embodiment is as follows: Figure 1 It can be seen that the primary particles on the surface of the positive electrode material precursor prepared in this embodiment are arranged regularly and are thin.

[0149] Figure 2 This is the X-ray diffraction pattern of the positive electrode material precursor prepared in this embodiment.

[0150] Example 2

[0151] Prepare a chemical formula Ni 0.33 Mn 0.33 Fe 0.34 The specific preparation method of the sodium ion positive electrode material precursor of (OH)2 is as follows:

[0152] This embodiment is carried out in a similar manner to that of embodiment 1, except that:

[0153] In step ②, the mass concentration of ammonia water in the base liquid is 4.0 g / L;

[0154] In step ③, after the coprecipitation reaction is carried out until the D50 of the slurry is 6 μm, air is introduced until the volume content of oxygen in the gaseous atmosphere is 0.7-0.9%. When the D50 of the slurry in the reactor is 10.5 μm, the feeding is stopped;

[0155] The mass concentration of ammonia water during the coprecipitation reaction was 4.0 g / L;

[0156] The unlisted parts are the same as those in Example 1.

[0157] Figure 3 This is the X-ray diffraction pattern of the positive electrode material precursor prepared in this embodiment.

[0158] Example 3

[0159] Prepare a chemical formula Ni 0.55 Mn 0.2 Fe 0.25 The specific preparation method of the sodium ion positive electrode material precursor of (OH)2 is as follows:

[0160] This embodiment is carried out in a similar manner to that of embodiment 1, except that:

[0161] In step ①: According to Ni0.55 Mn 0.2 Fe 0.25 The ratio of nickel, manganese and iron in (OH)2: nickel sulfate, ferrous sulfate and manganese sulfate are weighed and dissolved in deionized water to form a metal salt solution with a total metal ion concentration of 2 mol / L. The metal salt solution contains sulfuric acid, and the concentration of sulfuric acid in the metal salt solution is 0.018 mol / L;

[0162] In step ③, after the coprecipitation reaction is carried out until the D50 of the slurry is 8 μm, air is introduced until the volume content of oxygen in the gaseous atmosphere is 0.7-0.9%. When the D50 of the slurry in the reactor is 9.6 μm, the feeding is stopped;

[0163] The unlisted parts are the same as those in Example 1.

[0164] Example 4

[0165] Prepare a chemical formula Ni 0.33 Mn 0.33 Fe 0.34 The specific preparation method of the sodium ion positive electrode material precursor of (OH)2 is as follows:

[0166] This embodiment is carried out in a similar manner to that of embodiment 1, except that:

[0167] In step ②, the pH value of the base solution is 10.20;

[0168] In step ③, after the coprecipitation reaction is carried out until the D50 of the slurry is 5 μm, air is introduced until the volume content of oxygen in the gaseous atmosphere is 0.7-0.9%. When the D50 of the slurry in the reactor is 10.8 μm, the feeding is stopped;

[0169] The pH of the liquid phase was maintained at 10.70 during the coprecipitation reaction by controlling the amount of the precipitant solution.

[0170] The unlisted parts are the same as those in Example 1.

[0171] Example 5

[0172] Prepare a chemical formula Ni 0.33 Mn 0.33 Fe 0.34 The specific preparation method of the sodium ion positive electrode material precursor of (OH)2 is as follows:

[0173] This embodiment is carried out in a similar manner to that of embodiment 1, except that:

[0174] In step ①: According to Ni 0.33 Mn 0.0.33 Fe 0.0.34The ratio of nickel, manganese and iron in (OH)2: nickel sulfate, ferrous sulfate and manganese sulfate are weighed and dissolved in deionized water to form a metal salt solution with a total metal ion concentration of 1.5 mol / L. The metal salt solution contains sulfuric acid, and the concentration of sulfuric acid in the metal salt solution is 0.018 mol / L.

[0175] In step ③, after the coprecipitation reaction is carried out until the D50 of the slurry is 9 μm, air is introduced until the volume content of oxygen in the gaseous atmosphere is 0.7-0.9%. When the D50 of the slurry in the reactor is 10.5 μm, the feeding is stopped;

[0176] The reaction temperature of the coprecipitation reaction was 55°C;

[0177] The unlisted parts are the same as those in Example 1.

[0178] Example 6

[0179] Prepare a chemical formula Ni 0.33 Mn 0.33 Fe 0.34 The specific preparation method of the sodium ion positive electrode material precursor of (OH)2 is as follows:

[0180] This embodiment is carried out in a similar manner to that of embodiment 1, except that:

[0181] In step ①: According to Ni 0.33 Mn 0.33 Fe 0.34 The ratio of nickel, manganese and iron in (OH)2: nickel sulfate, ferrous sulfate and manganese sulfate are weighed and dissolved in deionized water to form a metal salt solution with a total metal ion concentration of 2.5 mol / L. The metal salt solution contains sulfuric acid, and the concentration of sulfuric acid in the metal salt solution is 0.018 mol / L;

[0182] In step ③, after the coprecipitation reaction is carried out until the D50 of the slurry is 7 μm, air is introduced until the volume content of oxygen in the gaseous atmosphere is 0.7-0.9%. When the D50 of the slurry in the reactor reaches 10.6 μm, the feeding is stopped;

[0183] The reaction temperature of the coprecipitation reaction was 40°C;

[0184] The unlisted parts are the same as those in Example 1.

[0185] Example 7

[0186] Prepare a chemical formula Ni 0.33 Mn 0.33 Fe 0.34 The specific preparation method of the sodium ion positive electrode material precursor of (OH)2 is as follows:

[0187] This embodiment is carried out in a similar manner to that of embodiment 1, except that:

[0188] In step ①: According to Ni 0.33 Mn 0.33 Fe 0.34 The ratio of nickel, manganese and iron in (OH)2: nickel sulfate, ferrous sulfate and manganese sulfate are weighed and dissolved in deionized water to form a metal salt solution with a total metal ion concentration of 2 mol / L. The metal salt solution contains sulfuric acid, and the concentration of sulfuric acid in the metal salt solution is 0.025 mol / L;

[0189] In step ③, after the coprecipitation reaction is carried out until the D50 of the slurry is 8 μm, air is introduced until the volume content of oxygen in the gaseous atmosphere is 0.7-0.9%. When the D50 of the slurry in the reactor reaches 9.9 μm, the feeding is stopped;

[0190] In step ④, the drying temperature is 100°C

[0191] The unlisted parts are the same as those in Example 1.

[0192] Comparative Example 1

[0193] Prepare a chemical formula Ni 0.33 Mn 0.33 Fe 0.34 The specific preparation method of the sodium ion positive electrode material precursor of (OH)2 is as follows:

[0194] This comparative example was carried out in a similar manner to Example 1, except that:

[0195] In step ④, the drying temperature is 140°C;

[0196] The unlisted parts are the same as those in Example 1.

[0197] Figure 4 This is the X-ray diffraction pattern of the positive electrode material precursor prepared in this comparative example.

[0198] Comparative Example 2

[0199] Prepare a chemical formula Ni 0.33 Mn 0.33 Fe 0.34 The specific preparation method of the sodium ion positive electrode material precursor of (OH)2 is as follows:

[0200] This comparative example was carried out in a similar manner to Example 1, except that:

[0201] In step ③, the flow rate of the precipitant solution is controlled so that the pH of the liquid phase material during the coprecipitation reaction is reduced from 10.30 every 4 hours, with a reduction of 0.1 each time, until the pH of the liquid phase material during the coprecipitation reaction reaches 10.10;

[0202] The unlisted parts are the same as those in Example 1.

[0203] Figure 5 This is the X-ray diffraction pattern of the positive electrode material precursor prepared in this comparative example.

[0204] Comparative Example 3

[0205] Prepare a chemical formula Ni 0.33 Mn 0.33 Fe 0.34 The specific preparation method of the sodium ion positive electrode material precursor of (OH)2 is as follows:

[0206] This comparative example was carried out in a similar manner to Example 1, except that:

[0207] In step ②, the pH value of the base solution is 10.50;

[0208] In step ③, the initial flow rate of the metal salt solution is 2 L / h, and the flow rate is increased every 4 hours, with each increase of 2 L / h until it reaches 6 L / h;

[0209] By controlling the flow rate of the precipitant solution, the pH of the liquid phase material during the coprecipitation reaction was reduced from 10.50 every 4 hours, with a reduction of 0.1 each time, until the pH of the liquid phase material during the coprecipitation reaction reached 10.30;

[0210] The reaction temperature of the coprecipitation reaction was 150°C;

[0211] The unlisted parts are the same as those in Example 1.

[0212] Figure 6 This is the X-ray diffraction pattern of the positive electrode material precursor prepared in this comparative example.

[0213] Comparative Example 4

[0214] Prepare a chemical formula Ni 0.33 Mn 0.33 Fe 0.34 The specific preparation method of the sodium ion positive electrode material precursor of (OH)2 is as follows:

[0215] This comparative example was carried out in a similar manner to Example 1, except that:

[0216] In step ③, the flow rate of the precipitant solution is controlled so that the pH of the liquid phase material during the coprecipitation reaction is reduced from 10.30 every 4 hours, with a reduction of 0.1 each time, until the pH of the liquid phase material during the coprecipitation reaction reaches 9.80;

[0217] The unlisted parts are the same as those in Example 1.

[0218] Comparative Example 5

[0219] Prepare a chemical formula Ni 0.33 Mn 0.33 Fe 0.34 The specific preparation method of the sodium ion positive electrode material precursor of (OH)2 is as follows:

[0220] This comparative example was carried out in a similar manner to Example 1, except that:

[0221] In step ②, the pH value of the base solution is 10.60, and the mass concentration of ammonia water is 5.5 g / L;

[0222] In step ③, after the coprecipitation reaction is carried out until the D50 of the slurry is 7 μm, air is introduced until the volume content of oxygen in the gaseous atmosphere is 0.7-0.9%. When the D50 of the slurry in the reactor is 8.5 μm, the feeding is stopped;

[0223] By controlling the flow rates of the precipitant solution and the complexing agent solution, the pH of the liquid phase was maintained at 10.60 and the mass concentration of the ammonia water was 5.5 g / L during the coprecipitation reaction.

[0224] During the coprecipitation reaction, nitrogen was introduced throughout the reaction (so that the volume content of oxygen in the gas phase atmosphere was ≤0.5%);

[0225] The unlisted parts are the same as those in Example 1.

[0226] Test Example 1

[0227] The sodium ion cathode material precursors prepared in the aforementioned embodiments and comparative examples were subjected to physical and chemical data tests, specifically:

[0228] 1. The length and width of the primary particles on the surface of the sodium ion cathode material precursor are measured by scanning electron microscopy combined with image recognition software (the length of the primary particle is its long diameter, i.e., the maximum length, and the width is the maximum width perpendicular to the long diameter);

[0229] 2. Particle size (D50) was measured using a Malvern 3000 laser particle size analyzer, with reference to standard GB / T19077-2016;

[0230] 3. The test reference standard for tap density (TD) is GB / T 5162-2021 Determination of tap density of metal powders;

[0231] 4. Peak intensity I of the (100) crystal plane of the cathode material precursor (100) Peak intensity I with (001) crystal plane (001) The ratio I (100) / I (001) The peak area ratios of the sharp peak and the bun peak in the diffraction angle 2θ range of 15-25° were determined by XRD. XRD was measured by X-ray diffractometer according to the reference standard GA / T 2079-2023. The crystal structure of each sample was tested by RigakuSmartLab 9kW X-ray diffractometer (XRD, Cu Kα) with a scanning range of 10-85° and a scanning rate of 4° / min.

[0232] The specific results are shown in Tables 1 and 2.

[0233] Table 1 Summary of precursor parameters of the embodiments of the present invention and comparative examples

[0234]

[0235]

[0236] Table 2 Summary of XRD parameters of precursors in Examples of the present invention and comparative examples

[0237] <![CDATA[I (100) / I (001) ]]> Peak area ratio (sharp peak / bun peak) Example 1 1.43 1.00 Example 2 1.98 0.54 Example 3 1.83 0.78 Example 4 1.74 0.89 Example 5 1.41 1.21 Example 6 1.39 1.35 Example 7 1.2 1.46 Comparative Example 1 2.52 0.49 Comparative Example 2 2.95 0.42 Comparative Example 3 4.2 0.37 Comparative Example 4 3.7 0.39 Comparative Example 5 3.2 0.45

[0238] Test Example 2

[0239] In the presence of an air atmosphere, the sodium ion positive electrode material precursors prepared in the aforementioned embodiments and comparative examples were mixed with sodium carbonate in a molar ratio of 1:1.05, and then sintered in a muffle furnace (heating to 850°C at a heating rate of 1°C / min for 12 h), and then cooled and sieved to obtain a sodium ion battery positive electrode material.

[0240] Assembling the battery:

[0241] The positive electrode material was mixed with polyvinylidene fluoride and acetylene black in a mass ratio of 8:1:1, N-methyl-pyrrolidone was added, and the mixture was evenly coated on an aluminum foil current collector to form the positive electrode. After drying, a CR2032 button cell was assembled in a glove box using a sodium metal sheet as the negative electrode, a 1 mol / L NaClO₄ solution as the electrolyte, and a glass fiber separator.

[0242] First, charge and discharge at a current density of 0.1C (1C = 150mAh / g) for 2 weeks for activation, then charge and discharge at a current density of 0.2C for 2 weeks, and finally charge and discharge at a current density of 1C for 50 cycles, with a test voltage range of 2-4.2V.

[0243] The electrochemical performance test data are shown in Table 3.

[0244] Table 3 Electrical performance parameters of the positive electrode materials prepared from the precursors of the present invention and the comparative examples

[0245]

[0246] From the above results, it can be seen that the ratio of the peak area of the sharp peak to the peak area of the steamed bun peak in the diffraction angle 2θ range of 15-25° of the sodium ion battery positive electrode material precursor provided by the present invention is 0.5-1.5, wherein the crystalline state can ensure a high structural order, which is beneficial to sodium ion transport and capacity retention; the partial amorphous state has a disordered atomic arrangement, which can absorb the stress during the charge and discharge process, maintain product stability, and thus improve the cycle performance of the sodium ion battery.

[0247] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as the contents disclosed by the present invention and fall within the scope of protection of the present invention.

Claims

1. A sodium ion battery cathode material precursor, characterized in that: The XRD spectrum of the positive electrode material precursor contains a sharp peak and a bun peak within a diffraction angle 2θ range of 15-25°, and the ratio of the peak area of the sharp peak to the peak area of the bun peak is 0.5-1.

5.

2. The cathode material precursor according to claim 1, characterized in that The peak intensity I of the (100) crystal plane of the positive electrode material precursor (100) Peak intensity I with (001) crystal plane (001) The ratio I (100) / I (001) is 1.2-2.6; optionally, the I (100) / I (001) It is 1.2-2.

0.

3. The cathode material precursor according to claim 1, characterized in that The chemical formula of the positive electrode material precursor is Ni x Mn y Fe z M 1-x-y-z (OH)2, wherein 0.2≤x≤0.6, 0.3≤y≤0.5, 0.2≤z≤0.5, and M is selected from at least one of Zn, Mg, Ca, Cu, Al, and Zr.

4. The cathode material precursor according to claim 1, characterized in that The positive electrode material precursor meets one or more of the following conditions: a. The D50 of the cathode material precursor is 8 μm-15 μm, preferably 9 μm-11 μm; b. The primary particles on the surface of the positive electrode material precursor are in the form of thin flakes; c. The length of the primary particles on the surface of the positive electrode material precursor is 500 to 2000 nm, preferably 800 to 1100 nm; d. The width of the primary particles on the surface of the positive electrode material precursor is 50-200 nm, preferably 70-90 nm; e. The tap density of the positive electrode material precursor is 1.8 to 2.2 g / m 3 , preferably 1.9 to 2.2 g / m 3 , more preferably 2.0 to 2.2 g / m 3 .

5. A method for preparing a cathode material precursor according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: mixing water, a precipitant solution, and a complexing agent solution to obtain a base solution; In a gas phase atmosphere, the metal salt solution, the precipitant solution and the complexing agent solution are introduced into the base liquid to perform a co-precipitation reaction until the slurry reaches a preset particle size; performing solid-liquid separation, alkali washing and drying on the slurry to obtain the positive electrode material precursor; The drying temperature is less than 140°C.

6. The preparation method according to claim 5, characterized in that The preparation method satisfies at least one of the following conditions: (1) The coprecipitation reaction is divided into a first stage and a second stage, wherein the volume content of oxygen in the gaseous atmosphere of the first stage is ≤0.5%, and the volume content of oxygen in the gaseous atmosphere of the second stage is 0.7-1.1%; (2) The metal salt solution contains Ni, Fe, Mn elements and a doping element M; (3) The sum of the concentrations of metal ions in the metal salt solution is 1.5-2.5 mol / L; (4) The precipitant solution is a sodium hydroxide solution; (5) The concentration of the precipitant solution is 8-12 mol / L; (6) The complexing agent solution is an ammonia solution; (7) The concentration of the complexing agent solution is 10-12 mol / L.

7. The preparation method according to claim 6, characterized in that The preparation method satisfies at least one of the following conditions: A. The metal salt solution further comprises sulfuric acid, wherein the concentration of the sulfuric acid in the metal salt solution is 0.01-0.03 mol / L; B. The pH value of the base solution is 10.20-10.70; C. The mass concentration of ammonia water in the base liquid is 3.5-4.0 g / L; D. The mass concentration of ammonia in the coprecipitation reaction system is 3.5-4.0 g / L; E. The pH value of the coprecipitation reaction is 10.20-10.70; F. The temperature of the coprecipitation reaction is 40-60°C; G. The stirring speed of the coprecipitation reaction is 100-400 rpm. Preferably, the initial stirring speed of the coprecipitation reaction is 310-330 rpm. When the D50 of the slurry is 4.8-5.2 μm, the stirring speed is reduced to 290-310 rpm. The stirring speed is reduced once every time the D50 of the subsequent slurry increases by 0.4-0.6 μm, and the reduction rate is 18-22 rpm each time. H, the alkali cleaning adopts the sodium hydroxide solution with a concentration of 1-2mol / L to carry out; I. The drying temperature is 100-120°C; J. The first stage is the coprecipitation reaction until the D50 of the slurry is 5 to 9 μm; K. The oxygen content in the gaseous atmosphere of the second stage is adjusted by introducing air.

8. A sodium ion battery cathode material, characterized in that The raw material of the sodium ion battery positive electrode material includes the sodium ion battery positive electrode material precursor according to any one of claims 1 to 4 or the sodium ion battery positive electrode material precursor prepared by the preparation method according to any one of claims 5 to 7.

9. A sodium ion battery, characterized in that: Comprising the sodium ion battery positive electrode material as claimed in claim 8.

10. An electrical equipment, characterized in that: Including the sodium ion battery as claimed in claim 9.

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