Sodium-ion battery positive electrode material and preparation method therefor, manganese-containing oxide, sodium-ion battery, and electric device

Abstract

A sodium-ion battery positive electrode material and a preparation method therefor, a manganese-containing oxide, a sodium-ion battery, and an electric device. When an XRD pattern of the sodium-ion battery positive electrode material comprises a first diffraction peak α at a diffraction angle 2θ of 15.5°-16.5°, a second diffraction peak β at a diffraction angle 2θ of 32.0°-33.0°, and a third diffraction peak ω at a diffraction angle 2θ of 37°-38.5°, the sodium-ion battery positive electrode material has higher initial efficiency, cycle and rate properties than a sodium-ion battery positive electrode material that does not comprise the three characteristic peaks.

Description

Sodium-ion battery cathode material, preparation method thereof, manganese-containing oxide, sodium-ion battery, and electrical equipment

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411044113.1, filed on July 31, 2024, entitled "Sodium-ion battery cathode material, preparation method thereof, manganese-containing oxide, sodium-ion battery, and electrical equipment", the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the technical field of sodium-ion batteries, in particular to a sodium-ion battery cathode material, a preparation method thereof, a manganese-containing oxide, a sodium-ion battery, and an electrical equipment. BACKGROUND

[0004] In recent years, sodium-ion batteries have been widely researched and rapidly developed and applied due to their excellent low-temperature performance, good safety, abundant resources, and low cost.

[0005] The cathode material is an important component of a sodium-ion battery and plays a key role in the performance of the battery. Sodium-ion battery cathode materials are generally divided into layered transition metal oxides, Prussian blue analogs, and polyanion compounds, among which layered transition metal oxides have high energy density, many types, and are easy to synthesize, and are considered to be the most likely to achieve industrialization of sodium-ion battery cathode materials.

[0006] During the sintering process of the sodium-ion battery layered cathode material by the high-temperature solid-phase method, part of the sodium ions do not form a layered structure with the transition metal into the material inside, but remain on the surface of the material to form alkaline substances, which react with the electrolyte during repeated charging and discharging, resulting in gas production in the battery cell and reducing the performance of the battery.

[0007] In order to improve the performance of the sodium-ion battery, the present application is proposed. SUMMARY

[0008] The present application provides a sodium-ion battery cathode material, a preparation method thereof, a manganese-containing oxide, a sodium-ion battery, and an electrical equipment to improve the initial efficiency, cycle performance, and rate performance of the sodium-ion battery.

[0009] The present application is implemented as follows:

[0010] In a first aspect, the present application provides a sodium-ion battery cathode material, wherein the XRD pattern of the sodium-ion cathode material includes a first diffraction peak alpha at a diffraction angle 2theta of 15.5°-16.5°, a second diffraction peak beta at a diffraction angle 2theta of 32.0°-33.0°, and a third diffraction peak omega at a diffraction angle 2theta of 37°-38.5°.

[0011] In an optional embodiment, the positive electrode material of the sodium ion battery satisfies one or more of the following conditions:

[0012] A. In the XRD pattern of the positive electrode material of the sodium ion battery, the intensity I of the third diffraction peak ω and the intensity I of the first diffraction peak α The ratio I ω / I α is 0.2 - 0.8;

[0013] B. In the XRD pattern of the positive electrode material of the sodium ion battery, the intensity I of the third diffraction peak ω and the intensity I of the second diffraction peak β The ratio I ω / I β is 0.7 - 2.1.

[0014] C. The positive electrode material of the sodium ion battery includes a matrix and a coating layer on the surface of the matrix;

[0015] D. The median particle size of the positive electrode material of the sodium ion battery is 2 μm - 10 μm;

[0016] E. The residual alkali content on the surface of the positive electrode material of the sodium ion battery is less than 1.5 wt.%.

[0017] In an optional embodiment, when the positive electrode material of the sodium ion battery includes a matrix and a coating layer on the surface of the matrix, the positive electrode material of the sodium ion battery satisfies one or more of the following conditions:

[0018] A’. The coating layer includes a manganese-containing oxide; optionally, the chemical formula of the manganese-containing oxide is Na k Mn x M y O2, where 0.5 < k ≤ 0.95, 0.72 ≤ x ≤ 1, x + y = 1, and M is at least one of the transition group elements other than Mn;

[0019] B’. The manganese element in the coating layer accounts for 0.2 wt.% - 6 wt.% of the matrix; optionally, the manganese element in the coating layer accounts for 0.5 wt.% - 3 wt.% of the matrix;

[0020] C’. The thickness of the coating layer is 10 nm - 100 nm.

[0021] In an optional embodiment, when the positive electrode material of the sodium ion battery includes a matrix and a coating layer on the surface of the matrix, the positive electrode material of the sodium ion battery satisfies one or more of the following conditions:

[0022] (1) The matrix is an O3-type layered oxide;

[0023] (2) The chemical formula of the matrix is Na h Ni a Mn b A c O2, where 0.5 < h ≤ 1.2, 0.15 ≤ a ≤ 0.45, 0.1 ≤ b ≤ 0.5, a + b + c = 1, and A is at least one of Cu, Mg, Zn, Ca, Fe, Co, Sb, Ti, Zr, Zn, Sn, Ce.

[0024] Second, the present invention provides a method for preparing a positive electrode material for a sodium-ion battery as described in any one of the foregoing embodiments, including: calcining a mixture including a manganese source and a matrix to obtain the positive electrode material for the sodium-ion battery;

[0025] Optionally, the mixture further includes an M source, and both the manganese source and / or the M source are selected from at least one of oxides, hydroxides, carbonates, and organic acid salts;

[0026] Optionally, the manganese source and / or the M source are nanoscale particles;

[0027] Optionally, the calcining includes placing the mixture in an oxygen-containing atmosphere and holding it at 450°C - 750°C for 3h - 10h;

[0028] Optionally, after the calcining, the calcined material is crushed and sieved to obtain the positive electrode material for the sodium-ion battery.

[0029] Third, the present invention provides a manganese oxide, and the XRD pattern of the manganese-containing oxide includes a first diffraction peak α at a diffraction angle 2θ of 15.5° - 16.5°, a second diffraction peak β at a diffraction angle θ of 32.0° - 33.0°, and a third diffraction peak ω at a diffraction angle 2θ of 37° - 38.5°.

[0030] In an optional embodiment, the manganese-containing oxide satisfies one or more of the following conditions:

[0031] a. In the XRD pattern of the manganese-containing oxide, the ratio I ω of the intensity I α of the third diffraction peak to the intensity I<00�0018>of the first diffraction peak is 0.2 - 0.8; α

[0032] b. In the XRD pattern of the manganese-containing oxide, the ratio I ω of the intensity I β of the third diffraction peak to the intensity I ω of the second diffraction peak is I β0.7-2.1;

[0033] c. The manganese-containing oxide is used for a coating layer of a sodium-ion positive electrode material.

[0034] In an optional embodiment, the chemical formula of the manganese-containing oxide is Na k Mn x M y O2, wherein 0.5 < k < 0.95, 0.72 < x < 1, x + y = 1, and M is at least one of transition elements other than Mn.

[0035] In a fourth aspect, the present application provides a sodium-ion battery, comprising the sodium-ion battery positive electrode material according to the foregoing embodiments.

[0036] In a fifth aspect, the present application provides an electrical equipment, comprising the sodium-ion battery according to the foregoing embodiments.

[0037] The present application has the following beneficial effects:

[0038] The sodium-ion battery positive electrode material provided by the embodiments of the present application forms a sodium-ion battery positive electrode material having three characteristic peaks in the XRD pattern, i.e., a first diffraction peak α at a diffraction angle 2θ of 15.5°-16.5°, a second diffraction peak β at a diffraction angle 2θ of 32.0°-33.0°, and a third diffraction peak ω at a diffraction angle 2θ of 37°-38.5°. Compared with a sodium-ion battery positive electrode material not including the three characteristic peaks, the sodium-ion positive electrode material has higher initial efficiency, cycle performance, and rate performance.

[0039] The manganese-containing oxide provided by the embodiments of the present application is applied to the coating of a sodium-ion battery positive electrode material when the XRD pattern thereof includes a first diffraction peak α at a diffraction angle 2θ of 15.5°-16.5°, a second diffraction peak β at a diffraction angle 2θ of 32.0°-33.0°, and a third diffraction peak ω at a diffraction angle 2θ of 37°-38.5°, which is beneficial to improving the initial efficiency, cycle performance, and rate performance of the positive electrode material. When the characteristic peaks do not meet the above requirements, the coating effect of the manganese-containing oxide applied to the coating of a sodium-ion battery positive electrode material is poorer than that without coating in terms of discharge specific capacity and rate performance. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0041] Figure 1 is an XRD pattern of the coated sodium-ion battery cathode material in Example 1;

[0042] Figure 2 is an XRD pattern of the uncoated cathode material in Comparative Example 1;

[0043] Figure 3 is an XRD pattern of the coated sodium-ion battery cathode material in Comparative Example 4;

[0044] Figure 4 is an SEM image of the coated sodium-ion battery cathode material in Example 1;

[0045] Figure 5 is an SEM image of the coated sodium-ion battery cathode material in Example 4;

[0046] Figure 6 is an SEM image of the coated sodium-ion battery cathode material in Example 10;

[0047] Figure 7 is an SEM image of the uncoated cathode material in Comparative Example 1;

[0048] Figure 8 is an SEM image of the uncoated cathode material in Comparative Example 3;

[0049] Figure 9 is a Mn element distribution map of the coated sodium-ion battery cathode material in Example 1;

[0050] Figure 10 is a Ni element distribution map of the coated sodium-ion battery cathode material in Example 1;

[0051] Figure 11 is an SEM image of the coated sodium-ion battery cathode material in Example 1;

[0052] Figure 12 is a STEM image of the coated sodium-ion battery cathode material in Example 1;

[0053] Figure 13 is a TEM image of the coated sodium-ion battery cathode material in Example 1. DETAILED DESCRIPTION

[0054] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. If specific conditions are not indicated in the embodiments, conventional conditions or the conditions recommended by the manufacturers are adopted. If the manufacturers of the reagents or instruments are not indicated, the reagents or instruments are conventional products that can be purchased in the market.

[0055] This invention provides a sodium-ion battery cathode material, wherein the XRD pattern of the sodium-ion battery cathode material includes a first diffraction peak α at a diffraction angle 2θ of 15.5°-16.5°, a second diffraction peak β at a diffraction angle 2θ of 32.0°-33.0°, and a third diffraction peak ω at a diffraction angle 2θ of 37°-38.5°. Specifically, the diffraction angle 2θ of the first diffraction peak α can be any value between 15.5°, 15.7°, 15.9°, 16.1°, 16.3°, 16.5° or 15.5°-16.5°; the diffraction angle 2θ of the second diffraction peak β can be any value between 32.0°, 32.2°, 32.4°, 32.6°, 32.8°, 33.0° or 32.0°-33.0°; and the diffraction angle 2θ of the third diffraction peak ω can be any value between 37°, 37.2°, 37.4°, 37.6°, 37.8°, 38.0°, 38.2°, 38.5° or 37°-38.5°.

[0056] The sodium-ion battery cathode material in this embodiment of the invention is formed by in-situ coating, resulting in a sodium-ion battery cathode material with the aforementioned three characteristic peaks in the XRD pattern. When its characteristic peaks meet the above requirements, compared with sodium-ion battery cathode materials that do not include the aforementioned three characteristic peaks, the sodium-ion battery cathode material has higher first-efficiency, cycle and rate performance.

[0057] In some embodiments, the intensity I of the third diffraction peak in the XRD pattern of the sodium-ion battery cathode material is... ω With the intensity of the first diffraction peak I α The ratio of I ω / I α It is 0.2-0.8, specifically it can be any value between 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.2-0.8.

[0058] In some embodiments, the intensity I of the third diffraction peak in the XRD pattern of the sodium-ion battery cathode material is... ω The intensity I of the second diffraction peak β The ratio of I ω / I β It is 0.7-2.1, specifically it can be any value between 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 or 0.7-2.1.

[0059] When the intensity of its characteristic peaks meets the above requirements, it is beneficial to further improve the discharge specific capacity and rate performance of the cathode material.

[0060] In some embodiments, the sodium-ion battery cathode material comprises a substrate and a coating layer on the surface of the substrate.

[0061] In some embodiments, the sodium-ion battery cathode material has a median particle size of 2-10 μm, specifically 2 μm, 4 μm, 6 μm, 8 μm, 10 μm or any value between 2 μm and 10 μm. If the particle size is too large, it is not conducive to the insertion and extraction of sodium ions. If the particle size is too small, it is not conducive to the uniform coating of the coating layer on the surface of the substrate particles.

[0062] In some embodiments, the sodium-ion battery cathode material has a residual alkali content of less than 1.5 wt.%, specifically 1.4 wt.%, 1.0 wt.%, 0.8 wt.%, 0.5 wt.%, 0.3 wt.%, 0.1 wt.%, 0 or any value less than 1.5 wt.%. The reduction of residual alkali content is conducive to reducing the amount of gas generated, while improving the capacity, stability and rate performance of the cathode material.

[0063] In some embodiments, when the sodium-ion battery cathode material comprises a substrate and a coating layer on the surface of the substrate, the coating layer comprises a manganese-containing oxide. k Mn x M y O2, wherein 0.5 < k < 0.95, 0.72 < x < 1, x + y = 1, and M is at least one of the transition group elements other than Mn. It can be understood that when x < 1, the manganese-containing oxide is doped with M elements; when x = 1, y = 0, i.e. the manganese-containing oxide is not doped with M elements.

[0064] The M element can be specifically selected from at least one of Ni, Cu, Zn, Mg, Ca, Fe, Co, Y, La, Sb, Al, Cr, Ti, Zr, Sn, Ce. Doping M elements in the coating layer is conducive to improving the partial electrical properties of the material.

[0065] In some embodiments, the manganese element in the coating layer accounts for 0.2wt.%-6wt.% of the substrate, and specifically can be 0.2wt.%, 0.4wt.%, 0.5wt.%, 1wt.%, 1.5wt.%, 2wt.%, 2.5wt.%, 3wt.%, 3.5wt.%, 4wt.%, 4.5wt.%, 5wt.%, 6wt.% or any value between 0.2wt.% and 6wt.%; optionally, the manganese element in the coating layer accounts for 0.5wt.%-3wt.% of the substrate. When the manganese element in the coating layer accounts for 0.5wt.%-3wt.% of the substrate, the coating effect is the best, and the initial efficiency, rate performance, capacity and retention rate are obviously improved. When a larger amount of coating in the range of 3wt.%-5wt.% is performed, the coating effect is slightly worse, but still better than that of the uncoated sample. When the coating of 6wt.% is performed, although the specific charge and discharge capacity is reduced, the initial efficiency, retention rate and rate performance are still better than those of the uncoated sample.

[0066] In some embodiments, the coating layer has a thickness of 10nm-100nm, and specifically can be 10nm, 20nm, 40nm, 60nm, 80nm, 100nm or any value between 10nm and 100nm; if the coating layer is too thick, the coating amount is too much, which will lead to the reduction of the specific charge and discharge capacity and the cycle performance, and if the coating layer is too thin, the coating amount is too little, which cannot achieve the purpose of improving the battery performance.

[0067] In some embodiments, when the sodium ion battery positive electrode material comprises a substrate and a coating layer on the surface of the substrate, the substrate is an O3-type layered oxide.

[0068] In some embodiments, the chemical formula of the substrate is Na h Ni a Mn b A c O2, wherein 0.5<h≤1.2, 0.15≤a≤0.45, 0.1≤b≤0.5, a+b+c=1, and A is at least one of Cu, Mg, Zn, Ca, Fe, Co, Sb, Ti, Zr, Zn, Sn, Ce.

[0069] The embodiments of the present application also provide a preparation method of the sodium ion battery positive electrode material according to any one of the preceding embodiments, which comprises: calcining a mixture comprising a manganese source and a substrate to obtain the sodium ion battery positive electrode material.

[0070] During the sintering process of the layered cathode material of sodium-ion battery, part of the sodium salt does not form a layered structure with transition metal and enters the interior of the material, and remains on the surface of the material to form alkaline substances. By adding a manganese source, the residual sodium on the surface is used to form a coating layer on the surface of the cathode material through in-situ reaction after the second sintering, which has the characteristic peaks in the XRD pattern, which is beneficial to improve the capacity, rate performance and cycle performance of the battery.

[0071] In some embodiments, the substrate can be prepared by the following preparation method: uniformly mixing a sodium source (such as sodium carbonate, sodium hydroxide, sodium nitrate, etc.) and a transition metal source (such as a precursor hydroxide, an oxide, a carbonate, an organic acid salt, a chloride, etc.) in a molar ratio of sodium to transition metal of 0.5-1.2:1, calcining under an oxygen-containing atmosphere at 650-1000°C for 10-15h, and then crushing and sieving through a 400-mesh sieve to obtain the cathode material substrate;

[0072] In some embodiments, the mixture further comprises an M source, and the manganese source and / or the M source are each selected from at least one of an oxide, a hydroxide, a carbonate and an organic acid salt; the mixture comprising the manganese source and / or the M source and the substrate is calcined, and during the calcination process, the manganese source and / or the M source react in-situ with the residual sodium carbonate and sodium hydroxide on the surface of the substrate to form a coating layer, which is coated on the surface of the substrate, and is beneficial to reduce the residual alkali on the surface of the cathode material, reduce the gas production phenomenon during the battery cycle process, and improve the high-pressure cycle stability of the battery.

[0073] In some embodiments, the manganese source and / or the M source are nano-sized particles; the nano-sized manganese source and / or the M source are used as coating raw materials to prepare a nano-scale coating layer, which is beneficial to improve the uniformity of the coating layer. The coating layer can reduce the corrosion of the electrolyte to the substrate material, and is also beneficial to the sodium ion extraction and embedding, and improve the capacity.

[0074] In some embodiments, the calcination comprises placing the mixture in an oxygen-containing atmosphere and maintaining the temperature at 450°C-750°C for 3h-10h; specifically, the constant temperature can be 450°C, 550°C, 650°C, 750°C or any value between 450°C and 750°C, and the constant temperature time can be 3h, 5h, 7h, 9h, 10h or any value between 3h and 10h; under this condition, on the one hand, the manganese source and / or the M source react in-situ with the residual sodium carbonate and sodium hydroxide on the surface of the substrate to form a coating layer; on the other hand, it is beneficial to ensure the bonding strength between the coating layer and the substrate, and ensure the cycle performance of the cathode material, while not affecting the crystal structure of the substrate.

[0075] In some embodiments, the calcined material is crushed and sieved after the calcination to obtain the cathode material of the sodium-ion battery. In some embodiments, a 400-mesh sieve is used for sieving treatment to obtain a cathode material with a target particle size.

[0076] An embodiment of the present invention also provides a manganese-containing oxide. The XRD pattern of the manganese-containing oxide includes a first diffraction peak α at a diffraction angle 2θ of 15.5°-16.5°, a second diffraction peak β at a diffraction angle 2θ of 32.0°-33.0°, and a third diffraction peak ω at a diffraction angle 2θ of 37°-38.5°.

[0077] In some embodiments, in the XRD pattern of the manganese-containing oxide, the intensity I of the third diffraction peak ω and the intensity I of the first diffraction peak α The ratio I of ω / I α is 0.2-0.8;

[0078] In some embodiments, in the XRD pattern of the manganese-containing oxide, the intensity I of the third diffraction peak ω and the intensity I of the second diffraction peak β The ratio I of ω / I β is 0.7-2.1;

[0079] In some embodiments, the manganese-containing oxide is used for the coating layer of the sodium-ion cathode material.

[0080] In some embodiments, the chemical formula of the manganese-containing oxide is Na k Mn x M [[ID=编号错误,应为35]] y O2, where 0.5 < k ≤ 0.95, 0.72 ≤ x ≤ 1, x + y = 1, and M is at least one of transition group elements other than Mn.

[0081] An embodiment of the present invention also provides a sodium-ion battery, including the sodium-ion battery cathode material described in the foregoing embodiment.

[0082] An embodiment of the present invention also provides an electricity-related device, including the sodium-ion battery described in the foregoing embodiment.

[0083] The features and properties of the present invention are further described in detail below in conjunction with embodiments. The description of the test methods for testing the products involved in the following embodiments and comparative examples is as follows:

[0084] 1. XRD was measured by an X-ray diffractometer and determined according to the reference standard GA / T 2079-2023;

[0085] 2. The particle size was tested using a Malvern 3000 laser particle size analyzer and determined according to the reference standard GB / T 19077-2016;

[0086] 3. EDS was used to determine the metal components in the cathode material particles by an X-ray energy spectrum scanner; Note: There is a possible error in the numbering in the original text. The numbering jumps from 34 to 36 without a 35. This has been noted in the translation for reference.

[0087] 4、Coating layer thickness can be observed by SEM and TEM photos taken after argon ion polishing;

[0088] 5、Residual alkali content is measured by lithium ion battery positive electrode material detection method, and magnetic foreign matter content and residual alkali content are measured according to the reference standard GB / T 41704-2022.

[0089] Example 1

[0090] The embodiment provides a preparation method of a sodium ion positive electrode material, and specifically comprises the following steps:

[0091] (1) According to the molar ratio of metal elements 0.96:0.3:0.3:0.22:0.1:0.08, the corresponding weights of Na2CO3, NiO, MnO2, TiO2, ZnO and CuO are weighed, and then added to the mixer at a rotating speed of 2000 r / min for 3 min. The uniformly mixed material is placed in a muffle furnace under air atmosphere at 970℃ for 12 hours, and then cooled with the furnace. After being broken by a universal pulverizer and sieved to 400 mesh, a positive electrode material matrix is obtained.

[0092] (2) The nano-MnCO3 is weighed according to the mass ratio of Mn element to the positive electrode material matrix 2%, and then placed in the mixer together with the positive electrode material matrix at a rotating speed of 1500 r / min for 1 min. The uniformly mixed material is placed in a muffle furnace under air atmosphere at 450℃ for 8 hours, and then broken and sieved to obtain a coated sodium ion battery positive electrode material.

[0093] Example 2

[0094] The embodiment provides a preparation method of a sodium ion positive electrode material, and specifically comprises the following steps:

[0095] (1) According to the molar ratio of metal elements 1:0.22:0.37:0.13:0.28, the corresponding weights of Na2CO3 (excess 2% relative to the theoretical sodium content), NiO, MnO2, CuO and Fe2O3 are weighed, and then added to the mixer at a rotating speed of 2000 r / min for 3 min. The uniformly mixed material is placed in a muffle furnace under air atmosphere at 950℃ for 12 hours, and then cooled with the furnace. After being broken by a universal pulverizer and sieved to 400 mesh, a positive electrode material matrix is obtained.

[0096] (2) Weigh the nano-Mn2O3 according to the mass ratio of Mn element to the taken positive electrode material substrate 5%, and then put it into the mixer together with the positive electrode material substrate at a speed of 1500 r / min for 1 min. Put the uniformly mixed material into the muffle furnace under air atmosphere, and keep the temperature at 700°C for 3 hours. After crushing and sieving, the coated sodium ion battery positive electrode material is obtained.

[0097] Example 3

[0098] The embodiment provides a preparation method of a sodium ion positive electrode material, which specifically comprises the following steps:

[0099] (1) According to the molar ratio of metal elements 1.02:0.32:0.32:0.36, the corresponding weights of Na2CO3 (excess 2% relative to the theoretical sodium content), NiO, MnO2 and Fe2O3 are weighed respectively, and then added into the mixer at a speed of 2000 r / min for 3 min. Put the uniformly mixed material into the muffle furnace under air atmosphere, and keep the temperature at 950°C for 12 hours. Then, cool it down with the furnace, crush it with the universal crusher, and sieve it with a 400 mesh sieve to obtain the positive electrode material substrate.

[0100] (2) Weigh the nano-Mn2O3 according to the mass ratio of Mn element to the taken positive electrode material substrate 5%, and then put it into the mixer together with the positive electrode material substrate at a speed of 1500 r / min for 1 min. Put the uniformly mixed material into the muffle furnace under air atmosphere, and keep the temperature at 700°C for 3 hours. After crushing and sieving, the coated sodium ion battery positive electrode material is obtained.

[0101] Example 4

[0102] The embodiment provides a preparation method of a sodium ion positive electrode material, which specifically comprises the following steps:

[0103] (1) Take the uncoated positive electrode material substrate obtained in Example 3, weigh the nano-Mn2O3 according to the mass ratio of Mn element to the taken positive electrode material substrate 0.5%, and then put it into the mixer together with the positive electrode material substrate at a speed of 1500 r / min for 1 min. Put the uniformly mixed material into the muffle furnace under air atmosphere, and keep the temperature at 700°C for 3 hours. After crushing and sieving, the coated sodium ion battery positive electrode material is obtained.

[0104] Example 5

[0105] The embodiment provides a preparation method of a sodium ion positive electrode material, which specifically comprises the following steps:

[0106] (1) Take the uncoated positive electrode material matrix obtained in Example 3, weigh the nano-Mn2O3 according to the mass ratio of Mn element to the taken positive electrode material matrix of 3%, then put it into the mixer together with the positive electrode material matrix at a speed of 1500 r / min for 1 min, put the uniformly mixed material into the muffle furnace under air atmosphere at 700°C for 3 hours, crush and sieve to obtain the coated sodium-ion battery positive electrode material.

[0107] Example 6

[0108] The embodiment provides a preparation method of a sodium-ion positive electrode material, and specifically comprises the following steps:

[0109] (1) Take the positive electrode material matrix obtained in Example 3, weigh the nano-Mn2O3 according to the mass ratio of Mn element to the taken positive electrode material matrix of 0.2%, then put it into the mixer together with the positive electrode material matrix at a speed of 1500 r / min for 1 min, put the uniformly mixed material into the muffle furnace under air atmosphere at 700°C for 3 hours, crush and sieve to obtain the coated sodium-ion battery positive electrode material.

[0110] Example 7

[0111] The embodiment provides a preparation method of a sodium-ion positive electrode material, and specifically comprises the following steps:

[0112] (1) Take the positive electrode material matrix obtained in Example 3, weigh the nano-Mn2O3 according to the mass ratio of Mn element to the taken positive electrode material matrix of 6%, then put it into the mixer together with the positive electrode material matrix at a speed of 1500 r / min for 1 min, put the uniformly mixed material into the muffle furnace under air atmosphere at 700°C for 3 hours, crush and sieve to obtain the coated sodium-ion battery positive electrode material.

[0113] Example 8

[0114] The embodiment provides a preparation method of a sodium-ion positive electrode material, and specifically comprises the following steps:

[0115] (1) Take the uncoated positive electrode material matrix obtained in Example 3, weigh the nano-TiO2 and nano-Mn2O3, wherein the mass ratio of Mn element in the nano-Mn2O3 to the taken positive electrode material matrix is 2%, and the mass ratio of Ti element in the nano-TiO2 to the taken positive electrode material matrix is 0.22%, then put them into the mixer together with the positive electrode material matrix at a speed of 1500 r / min for 1 min, put the uniformly mixed material into the muffle furnace under air atmosphere at 700°C for 3 hours, crush and sieve to obtain the coated sodium-ion battery positive electrode material.

[0116] Example 9

[0117] The embodiment provides a preparation method of a sodium ion positive electrode material, and specifically comprises the following steps.

[0118] (1) taking the uncoated positive electrode material substrate obtained in Example 3, nanometer Y2O3 and nanometer Mn2O3 are weighed, wherein the mass ratio of Mn element in the nanometer Mn2O3 to the taken positive electrode material substrate is 2%, and the mass ratio of Y element in the nanometer Mn2O3 to the taken positive electrode material substrate is 0.22%, then the positive electrode material substrate is placed in a mixer at a rotating speed of 1500 r / min together with the nanometer Y2O3 and the nanometer Mn2O3, and mixed for 1 min, the uniformly mixed material is placed in a muffle furnace under an air atmosphere, and is kept at 700 DEG C for 3 hours, after crushing and sieving, a coated sodium ion battery positive electrode material is obtained.

[0119] Example 10

[0120] The embodiment provides a preparation method of a sodium ion positive electrode material, and specifically comprises the following steps.

[0121] (1) taking the uncoated positive electrode material substrate obtained in Example 3, nanometer CeO2 and nanometer Mn2O3 are weighed, wherein the mass ratio of Mn element in the nanometer Mn2O3 to the taken positive electrode material substrate is 2%, and the mass ratio of Ce element in the nanometer Mn2O3 to the taken positive electrode material substrate is 0.22%, then the positive electrode material substrate is placed in a mixer at a rotating speed of 1500 r / min together with the nanometer Y2O3 and the nanometer Mn2O3, and mixed for 1 min, the uniformly mixed material is placed in a muffle furnace under an air atmosphere, and is kept at 700 DEG C for 3 hours, after crushing and sieving, a coated sodium ion battery positive electrode material is obtained.

[0122] Comparative Example 1

[0123] In the comparative example, the uncoated positive electrode material substrate obtained in Example 1 is not treated, and is used as a sodium ion battery positive electrode material.

[0124] Comparative Example 2

[0125] In the comparative example, the uncoated positive electrode material substrate obtained in Example 2 is not treated, and is used as a sodium ion battery positive electrode material.

[0126] Comparative Example 3

[0127] In the comparative example, the uncoated positive electrode material substrate obtained in Example 3 is not treated, and is used as a sodium ion battery positive electrode material.

[0128] Comparative Example 4

[0129] The embodiment provides a preparation method of a sodium ion positive electrode material, and specifically comprises the following steps.

[0130] The positive electrode material substrate obtained in Example 3 was placed in humid air with a humidity of 65% for 24 h, and then the treated MnO2 was weighed according to a mass ratio of Mn element to the taken positive electrode material substrate of 2%, and then was put into a mixer at a rotating speed of 1500 r / min for mixing for 1 min. The uniformly mixed material was put into a muffle furnace under an air atmosphere at 720°C for 8 h. After crushing and sieving, a coated sodium-ion battery positive electrode material was obtained.

[0131] The preparation conditions of the sodium-ion battery positive electrode materials in the above examples and comparative examples are shown in Table 1, and the residual alkali data and peak intensity ratio in the XRD image are shown in Table 2.

[0132] Table 1: Preparation conditions of sodium-ion battery positive electrode materials in examples and comparative examples

[0133] Table 2: Residual alkali, median particle size and peak intensity ratio data of examples and comparative examples

[0134] The sodium-ion battery positive electrode materials prepared in the above examples and comparative examples were uniformly stirred with a conductive agent and a binder in an NMP solvent, and then were coated on an aluminum foil. Then, baking, rolling and slicing were performed to prepare a positive electrode sheet. Finally, the positive electrode sheet was assembled with a separator, a sodium sheet and a gasket to form a sodium-ion button cell.

[0135] The prepared CR2032 sodium-ion button cell was tested by using a battery test cabinet. The test conditions were as follows: a glass fiber separator was used, the electrolyte was 1 mol / L sodium perchlorate, the solvent volume ratio was EC:PC = 1:1, 5% FEC was added, the sodium sheet was a negative electrode, the test voltage range was 2.0-4.2V and 2.0-4.3V, and the test temperature was 25±1°C. The specific test conditions of the button cell were as follows: charging to 4.2 / 4.3V at 0.1C, discharging to 2.0V at 0.1C, cycling for 2 weeks, charging to 4.2 / 4.3V at 0.2C, discharging to 2.0V at 0.2C, cycling for 2 weeks, and finally charging to 4.2 / 4.3V at 1C, discharging to 2.0V at 1C, and thus 1C cycling for 50 weeks. The specific test results are shown in Tables 3 and 4.

[0136] Table 3: 2.0-4.2V electrochemical test

[0137] Table 4: 2.0-4.3V electrochemical test

[0138] The XRD diffraction patterns of the sodium-ion battery positive electrode materials in Example 1, Comparative Example 1 and Comparative Example 4 are shown in Figures 1-3. As can be seen from Figure 1, the positive electrode material after in-situ coating appears Na0.91 The characteristic peaks of NiO2 are the first diffraction peak at a diffraction angle of 15.5°-16.5° (2θ), the second diffraction peak at a diffraction angle of 32.0°-33.0° (2θ), and the third diffraction peak at a diffraction angle of 37°-38.5° (2θ). In comparison, the XRD patterns obtained in other embodiments also showed the first, second, and third diffraction peaks within the same diffraction angle range. No Na was found in the uncoated cathode material in Comparative Example 1. 0.91 The characteristic peaks of NiO2, as shown in Figure 2 and Figure 1, prove that Na was generated through in-situ Mn coating in Example 1. 0.91 A NiO2-structured isomorphic phase coating layer. As shown in Figure 3, the XRD pattern of the coated sodium-ion battery cathode material prepared in Comparative Example 4 only shows characteristic peaks of the O3-type matrix material and P2-type sodium manganate; no Na2-type characteristic peaks were observed. 0.91 Characteristic peaks of NiO2.

[0139] Figures 4-8 show the SEM images of the sodium-ion battery cathode materials in Examples 1, 4, 10, Comparative Example 1, and Comparative Example 3. Figure 4 shows a nanoscale coating layer in Example 1 after in-situ coating treatment. Similarly, Figures 5 and 6 show nanoscale coating layers on the surface of the cathode materials after in-situ coating treatment. Figures 7 and 8 show the uncoated cathode materials; the uncoated sodium-ion battery cathode materials show finely broken particles and a large amount of residual sodium phase on their surface.

[0140] The Mn and Ni element distribution maps and SEM images of the coated sodium-ion battery cathode material in Example 1 are shown in Figures 9-11. In Figure 9, after argon ion polishing, Mn is enriched on the outer surface of the sample and has a relatively uniform thickness. In Figure 10, Ni is not enriched on the outer surface of the sample, thus proving that a uniform Mn-containing nanoscale coating layer has been formed on the sample surface. The uniform nanoscale coating layer can also be seen in the SEM image in Figure 11, with a measured thickness of 21.14 nm.

[0141] Figure 12 shows the Z-contrast image of the coated sodium-ion battery cathode material in Example 1 obtained using STEM (scanning transmission imaging). The lower right corner shows the diffraction pattern obtained by Fourier transform at the location marked by the white box in the figure. After calibration, this pattern can be compared with that of monoclinic Na. 0.91 The

[0101] band pattern of the NiO2 phase matches perfectly, wherein Na 0.91The lattice constants of the NiO2 phase are a = 0.495 nm, b = 0.286 nm, c = 0.647 nm, α = γ = 90°, and β = 121.5°. Figure 13 is a high-resolution TEM (transmission electron microscope) image of the coated sodium-ion battery cathode material in Example 1. The white dashed lines to the left and below represent the coating layer with a thickness exceeding 20 nm. Fourier transform of this layer yields the electron diffraction pattern in the lower right corner. After calibration, this pattern is compared with that of monoclinic Na... 0.91 The

[0111] band pattern of the NiO2 phase matches. It should be emphasized that the diffraction patterns in Figures 12 and 13 cannot be identified by the P2 phase.

[0142] Electrochemical performance tests on various examples and comparative examples revealed that in-situ coating improved the initial efficiency and rate performance of the batteries in the examples, as well as the retention rate after 50 cycles. When the XRD pattern of the manganese oxide used as the coating layer did not include the first diffraction peak at a diffraction angle of 15.5°–16.5° 2θ, the second diffraction peak at a diffraction angle of 32.0°–33.0° 2θ, and the third diffraction peak at a diffraction angle of 37°–38.5° 2θ, the performance of the sodium-ion cathode material was worse than that with the aforementioned three characteristic peaks, and the coating effect was even lower than that without coating in terms of discharge specific capacity and rate performance.

[0143] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A sodium-ion battery cathode material, characterized in that, The XRD pattern of the sodium-ion battery cathode material comprises a first diffraction peak α at a diffraction angle 2θ of 15.5°-16.5°, a second diffraction peak β at a diffraction angle 2θ of 32.0°-33.0°, and a third diffraction peak ω at a diffraction angle 2θ of 37°-38.5°.

2. The sodium-ion battery cathode material of claim 1, wherein, The sodium-ion battery cathode material comprises a manganese oxide phase isomorphic with Na 0.91 NiO2.

3. The sodium-ion battery cathode material of claim 1 or 2, wherein, The sodium-ion battery cathode material satisfies one or more of the following conditions: A. In the XRD pattern of the sodium-ion battery cathode material, the intensity I of the third diffraction peak ω With the intensity I of the first diffraction peak α The ratio of I ω / I α It is 0.2-0.8; B. the ratio I ω of the intensity of the third diffraction peak to the intensity of the second diffraction peak in the XRD pattern of the sodium-ion battery cathode material is 0.7-2.1; and β C. the sodium-ion battery cathode material has a specific capacity of 100-200 mAh / g at a current density of 0.1 C. ω D. the sodium-ion battery cathode material has a specific capacity of 100-200 mAh / g at a current density of 0.1 C. β E. the sodium-ion battery cathode material has a specific capacity of 100-200 mAh / g at a current density of 0. C. The sodium-ion battery cathode material comprises a substrate and a coating layer on the surface of the substrate; D. The median particle size of the sodium-ion battery cathode material is 2 μm-10 μm; E. The surface residual alkali content of the sodium-ion battery cathode material is less than 1.5 wt.%.

4. The sodium-ion battery cathode material of claim 3, wherein, When the sodium-ion battery cathode material comprises a substrate and a coating layer on the surface of the substrate, The sodium-ion battery cathode material satisfies one or more of the following conditions: A'. The cladding layer comprises a manganese-containing oxide; optionally, the manganese-containing oxide has a chemical formula of Na k Mn x M y O2, where 0.5 < k < 0.95, 0.72 < x < 1, x + y = 1, M is at least one of the transition group elements other than Mn; B'. The manganese element in the coating layer accounts for 0.2 wt.%-6 wt.% of the substrate; optionally, the manganese element in the coating layer accounts for 0.5 wt.%-3 wt.% of the substrate; C'. The thickness of the coating layer is 10 nm-100 nm.

5. The sodium-ion battery cathode material of claim 3, wherein, When the sodium-ion battery cathode material comprises a substrate and a coating layer on the surface of the substrate, the sodium-ion battery cathode material satisfies one or more of the following conditions: (1) The substrate is an O3-type layered oxide; (2) the chemical formula of the base is Na h Ni a Mn b A c O2, wherein 0.5 < h < 1.2, 0.15 < a < 0.45, 0.1 < b < 0.5, a + b + c = 1, and A is at least one of Cu, Mg, Zn, Ca, Fe, Co, Sb, Ti, Zr, Zn, Sn, Ce.

6. A method of preparing a sodium-ion battery cathode material as claimed in any one of claims 1 to 5, characterized in that, Comprising: calcining a mixture comprising a manganese source and a substrate to obtain the sodium-ion battery cathode material; Optionally, the mixture further comprises an M source, and the manganese source and / or the M source are selected from at least one of oxides, hydroxides, carbonates, and organic acid salts; Optionally, the manganese source and / or the M source are nano-sized particles; Optionally, the calcining comprises placing the mixture in an oxygen-containing atmosphere and maintaining at 450°C-750°C for 3 h-10 h; Optionally, after the calcining, the calcined material is crushed and sieved to obtain the sodium-ion battery cathode material.

7. A manganese oxide-containing material, characterized in that, The XRD pattern of the manganese-containing oxide comprises a first diffraction peak α at a diffraction angle 2θ of 15.5°-16.5°, a second diffraction peak β at a diffraction angle 2θ of 32.0°-33.0°, and a third diffraction peak ω at a diffraction angle 2θ of 37°-38.5°.

8. The manganese oxide-containing material of claim 7, wherein, The manganese oxide-containing compound and Na 0.91 NiO2same structure.

9. Manganese oxide-containing according to claim 7 or 8, characterized in that, The manganese-containing oxide satisfies one or more of the following conditions: a. the ratio I ω of the intensity of the third diffraction peak to the intensity of the first diffraction peak in the XRD pattern of the manganese oxide-comprising material is 0.2-0.

8. α ω α 0.2-0.8.​​ b. the ratio I ω of the intensity of the third diffraction peak to the intensity of the second diffraction peak in the XRD pattern of the manganese oxide-comprising material is 0.7-2.

1. β ω β 0.7-2.1.​​ c. The manganese-containing oxide is used for a coating layer of a sodium-ion cathode material.

10. The manganese oxide-containing material of any one of claims 7-9, wherein the manganese oxide-containing material has a BET surface area of at least 50 m2 / g. The chemical formula of the manganese-containing oxide is Na k Mn x M y O2, wherein 0.5 < k < 0.95, 0.72 < x < 1, x + y = 1, and M is at least one of the transition group elements other than Mn.

11. A sodium-ion battery, characterized in that, Comprising at least one of the sodium-ion battery cathode material according to any one of claims 1-5, the sodium-ion battery cathode material prepared by the preparation method according to claim 6, or the manganese-containing oxide according to any one of claims 7-10.

12. An electrical device, comprising: Comprising the sodium-ion battery according to claim 11.

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